JP7577008B2 - Interlayer film and laminated glass sandwiched between two sheets of inorganic glass - Google Patents

Description

The present invention relates to an interlayer film that is sandwiched between two sheets of inorganic glass, and to laminated glass.

2. Description of the Related Art Laminated glass, which is a combination of inorganic glass and an interlayer film, is known to be useful for preventing scattering of glass fragments when the glass is broken or for improving crime prevention.
As a resin capable of producing such an interlayer film, a composition containing a polyvinyl acetal resin, typically a polyvinyl butyral (PVB) resin plasticized with a plasticizer, is widely used. Although the PVB resin can provide excellent performance as an interlayer film, there are cases where improved strength is required, particularly in applications where the film is used for a long period of time at high temperatures (e.g., 50°C). On the other hand, it has also been proposed to use a laminate of a layer containing a PVB resin and a layer containing a resin such as a polycarbonate resin as an interlayer film (Patent Documents 1 to 5).

Japanese Patent Application Publication No. 8-142282 International Publication No. 2011/016495 Japanese Unexamined Patent Publication No. 4-282243 International Publication No. 2015/129758 International Publication No. 2015/093352

"Effective laminates for the design of glass", Proceedings of the Glass Performance Days, Tampere, Finland (2009)

However, according to the studies of the present inventors, the strength of any of the conventional interlayer films as described above may be insufficient, particularly after long periods at high temperatures, and improved strength may be required. Also, there is a demand for interlayer films with better handleability in order to improve the work efficiency during the production of laminated glass.
Therefore, an object of the present invention is to provide an interlayer film that can provide laminated glass that has excellent penetration resistance and heat resistance, as well as sufficient strength even in applications where it is used for long periods of time at high temperatures (e.g., 50°C), and that is easy to handle, and to provide laminated glass in which such an interlayer film is sandwiched between two sheets of inorganic glass.

In order to solve the above problems, the present inventors have conducted extensive research into interlayer films and laminated glass, and have completed the present invention. That is, the present invention includes the following preferred embodiments.
[1] An interlayer film used by being sandwiched between two sheets of inorganic glass,
The intermediate film includes a laminate having adhesive layers (II) containing an adhesive resin on both sides of a substrate layer (I) containing a hard resin,
The following formula (1):
Shear relaxation modulus G(t=f ^-1 )=G'(f)－0.4G''(0.5f) (1)
[In formula (1), f is a frequency of 1.2×10 ⁻⁵ Hz, G′(f) is the shear storage modulus (MPa) at 50° C., and G″(0.5f) is the shear loss modulus (MPa) at 50° C.]
The shear relaxation modulus G ₁ (t=f ⁻¹ ) of the interlayer film is 0.80 MPa or more,
the shear relaxation modulus G 2 (t=f -1 ) of the interlayer film, represented by the above formula (1) [in formula (1), f is a frequency of 3.2×10 ^-9 Hz, G'(f) is the shear storage modulus (MPa) at 50° C., and G'_' ( ^0.5f ) is the shear loss modulus (MPa) at 50° C.], is 0.20 MPa or more,
The following formula (2):
The bending stiffness of the laminate at 25°C is 6 N·mm or more and 70 N·mm or less.
[2] The shear relaxation modulus of each of the m base layers and the 2m adhesive layers included in the interlayer film and the thickness ratio of each layer are used to calculate the shear relaxation modulus. The shear relaxation modulus is calculated using the following formula (3):
[The shear relaxation modulus of each layer in formula (3) is the shear relaxation modulus at 50° C. and 1.2×10 ⁻⁵ Hz, and M is an integer of 1 to 7]
The shear relaxation modulus G ₁ (t) of the interlayer film is 0.80 MPa or more,
The interlayer film according to [1] above, wherein the shear relaxation modulus G 2 (t) of the interlayer film, represented by the above formula (3) [wherein the shear relaxation modulus of each layer in formula (3) is the shear relaxation modulus at 50° C. and _3.2 ×10 ⁻⁹ Hz, and M is an integer from 1 to 7], is 0.20 MPa or more.
[3] The intermediate film according to [1] or [2], wherein in the laminate, the thickness of the base material layer (I) is greater than the thickness of either of the two adhesive layers (II).
[4] The intermediate film according to any one of [1] to [3], wherein in the laminate, the thickness of the base material layer (I) is greater than the total thickness of the two adhesive layers (II).
[5] In a four-point bending test with a support distance of 0.3 m on a laminated glass obtained by sandwiching the above interlayer film between two pieces of float glass having a thickness of 3.0 mm and a Young's modulus of 7.16×10 ⁴ MPa,
The following formula (4):
[ _In formula (4), _hs = 0.5 × ( _h1 + _h2 ) + _{hv , Is} = _hs2 × ^h1 × _h2 ÷ ( _h1 + _h2 ), _h1 and _h2 are the thicknesses of the two float glasses (unit: mm), _hv is the thickness of the interlayer (unit: mm), E is the Young's modulus of the float glass (unit: MPa), G(t = f-1) is the above _G1 (t = f ^{-1 )} (unit: MPa), and a is the distance between the supports in the four-point bending test (unit: m)]
The shear transfer coefficient Γ ₁ of the interlayer film is 0.10 or more,
The interlayer film according to any one of the above [1] to [4], wherein the shear transfer coefficient Γ2 of the interlayer film represented by the above formula (4) [in formula (4), hs _{, Is} , _h1 , _h2 , hv, _E and a are as described above, and _G (t=f- ¹ ) is the above _G2 (t=f ^-1 ) (unit: MPa)] is 0.02 or more.
[6] The interlayer film according to any one of [1] to [5] above, wherein the interlayer film has a penetration resistance of 12 J or more, as measured in a drop weight impact test in accordance with ASTM D3763 under conditions of a measurement temperature of 23°C, a load of 2 kg, and an impact speed of ⁹ m s
[7] The interlayer film according to any one of [1] to [6] above, wherein the base layer (I) contains a polycarbonate resin as the hard resin.
[8] The interlayer film according to any one of [1] to [7], wherein in the laminate, at least one adhesive layer (II) contains a polyvinyl acetal resin as an adhesive resin.
[9] The intermediate film according to any one of [1] to [8], wherein in the laminate, at least one adhesive layer (II) further contains a plasticizer.
[10] The interlayer film according to [9], wherein the plasticizer is at least one selected from the group consisting of carboxylate-based plasticizers, phosphate-based plasticizers, organic phosphite-based plasticizers, carboxylate polyester-based plasticizers, carbonate polyester-based plasticizers, polyalkylene glycol-based plasticizers, and ester compounds of hydroxycarboxylic acids and polyhydric alcohols.
[11] The interlayer film according to any one of [1] to [10] above, wherein the melt viscosity (η ₁ ) of the resin material constituting the base layer (I) is 1×10 ² Pa· ^s or more and 1×10 ⁴ Pa·s or less, the melt viscosities (η ₂ ) and (η ₃ ) of the resin materials constituting each adhesive layer (II) are, respectively, 1×10 ² Pa·s or more and 1×10 ⁴ Pa·s or less, and the melt viscosity ratios (η ₁ /η ₂ ) and (η ₁ /η ₃ ) are 1.0 or more and 4.0 or less, as measured in accordance with JIS K 7199 at a temperature of 230° C. and a shear rate of 60 s-1.
[12] A method for producing the interlayer film according to any one of [1] to [11] above, comprising providing an adhesive layer (II) on both sides of the base layer (I) by co-extrusion to produce a laminate.
[13] A laminated glass having inorganic glass, an interlayer film, and inorganic glass laminated in this order,
The intermediate film includes a laminate having adhesive layers (II) containing an adhesive resin on both sides of a substrate layer (I) containing a hard resin,
The following formula (1):
Shear relaxation modulus G(t=f ^-1 )=G'(f)－0.4G''(0.5f) (1)
[In formula (1), f is a frequency of 1.2×10 ⁻⁵ Hz, G′(f) is the shear storage modulus (MPa) at 50° C., and G″(0.5f) is the shear loss modulus (MPa) at 50° C.]
The shear relaxation modulus G ₁ (t=f ⁻¹ ) of the interlayer film is 0.80 MPa or more,
the shear relaxation modulus G 2 (t=f -1 ) of the interlayer film, represented by the above formula (1) [in formula (1), f is a frequency of 3.2×10 ^-9 Hz, G'(f) is the shear storage modulus (MPa) at 50° C., and G'_' ( ^0.5f ) is the shear loss modulus (MPa) at 50° C.], is 0.20 MPa or more,
The following formula (2):
The bending rigidity of the laminate at 25°C is 6 N mm or more and 70 N mm or less.
[14] The laminated glass according to the above [13], wherein in the laminate, the thickness of the base material layer (I) is greater than the total thickness of the two adhesive layers (II).
[15] The laminated glass according to [13] or [14], wherein in the laminate, at least one adhesive layer (II) contains a polyvinyl acetal resin as an adhesive resin.
[16] The laminated glass according to any one of [13] to [15] above, wherein in the laminate, at least one of the adhesive layers (II) further contains a plasticizer.
[17] The laminated glass according to the above [16], wherein the plasticizer is one or more selected from the group consisting of carboxylate-based plasticizers, phosphate-based plasticizers, organic phosphite-based plasticizers, carboxylate polyester-based plasticizers, carbonate polyester-based plasticizers, polyalkylene glycol-based plasticizers, and ester compounds of hydroxycarboxylic acids and polyhydric alcohols.
[18] The laminated glass according to any one of [13] to [17] above, wherein the melt viscosity (η ₁ ) of the resin material constituting the base material layer (I) is 1×10 ² Pa· ^s or more and 1×10 ⁴ Pa·s or less, the melt viscosities (η ₂ ) and (η ₃ ) of the resin materials constituting each adhesive layer (II) are, respectively, 1×10 ² Pa·s or more and 1×10 ⁴ Pa·s or less, and the melt viscosity ratios (η ₁ /η ₂ ) and (η ₁ /η ₃ ) are 1.0 or more and 4.0 or less, as measured in accordance with JIS K 7199 at a temperature of 230° C. and a shear rate of 60 s -1.

The present invention can provide laminated glass that has excellent penetration resistance and heat resistance, as well as sufficient strength even in applications where it is used for long periods at high temperatures (e.g., 50°C), and can provide an interlayer film that is easy to handle, and a laminated glass in which such an interlayer film is sandwiched between two sheets of inorganic glass.

FIG. 1 is a schematic diagram of an apparatus for producing an interlayer film according to one embodiment of the present invention. 1 is a schematic cross-sectional view of a laminated glass according to one embodiment of the present invention. FIG. 2 is a schematic diagram showing a compressive shear test. FIG. 2 is a schematic diagram showing a test sample used in a thermal creep resistance test of laminated glass. FIG. 2 is a schematic diagram showing a thermal creep resistance test of laminated glass.

[Interlayer film]
The interlayer film in the present invention is used by being sandwiched between two sheets of inorganic glass. The interlayer film includes one or more laminates each including a substrate layer (I) containing a hard resin and an adhesive layer (II) containing an adhesive resin on both sides of the substrate layer (I).
In a preferred embodiment of the present invention, the interlayer film is made of one or more laminates from the viewpoint of the shear transfer coefficient described below. In this embodiment, the interlayer film does not include any layer other than the layer included in the laminate, or does not include any layer other than the layer included in the laminate and any structure described below.
When the interlayer contains one laminate, the interlayer has a configuration, for example, as shown in Fig. 2. In this embodiment, the interlayer 41 is sandwiched between two sheets of inorganic glass 21, and is made of a laminate having adhesive layers (II) 31 on both sides of a base layer (I) 32. Note that in Fig. 2 and Figs. 1 and 3 to 5 described below, the dimensions and ratios of the components are appropriately changed to make the drawings easier to see.
The interlayer film may include two or more laminates. For example, when the interlayer film includes two laminates, the interlayer film has a structure of adhesive layer (II)/base layer (I)/adhesive layer (II)/adhesive layer (II)/base layer (I)/adhesive layer (II).
When the interlayer contains one laminate, it can be preferably used in applications requiring particularly excellent bending strength. When the interlayer contains two or more laminates, the materials and thicknesses of the base material layers (I) and adhesive layers (II) constituting the multiple laminates may be the same or different from each other. The number of laminates contained in the interlayer is usually 1 to 7, preferably 1 to 3.

The interlayer film may optionally include a structure other than the laminate on the entire surface or part of the interlayer film, as long as it does not interfere with the purpose and effect of the present invention. Furthermore, such a structure may be located at any position when the interlayer film is observed from a cross section. That is, for example, it may be located on the outside of the interlayer film, or it may be located between the base material layer (I) and the adhesive layer (II), or it may be inserted between the laminates when the interlayer film includes multiple laminates. Examples of such structures include a conductive structure, a sound-insulating structure, a design or design layer, and combinations thereof.

In the present invention, the compound represented by the following formula (1):
Shear relaxation modulus G(t=f ^-1 )=G'(f)－0.4G''(0.5f) (1)
[In formula (1), f is a frequency of 1.2×10 ⁻⁵ Hz, G′(f) is the shear storage modulus (MPa) at 50° C., and G″(0.5f) is the shear loss modulus (MPa) at 50° C.]
The shear relaxation modulus G ₁ (t=f ⁻¹ ) of the interlayer film is 0.80 MPa or more,
The shear relaxation modulus G 2 (t=f -1 ) of the interlayer film, represented by the above formula (1) [in formula (1), f is a frequency of 3.2 × 10 ^-9 Hz, G'(f) is the shear storage modulus (MPa) at 50°C, and G'_' ( ^0.5f ) is the shear loss modulus (MPa) at 50°C], is 0.20 MPa or more.
If the shear relaxation modulus G ₁ (t=f ⁻¹ ) of the interlayer film is less than 0.80 MPa, or the shear relaxation modulus G ₂ (t=f ⁻¹ ) is less than 0.20 MPa, it is difficult to obtain a laminated glass having sufficient strength (particularly bending strength) even in applications where the glass is used at high temperatures for long periods of time.

The shear relaxation modulus G ₁ (t=f ^-1 ) is preferably 1.0 MPa or more, more preferably 1.2 MPa or more, more preferably 1.5 MPa or more, more preferably 2.0 MPa or more, more preferably 4.0 MPa or more, more preferably 7.0 MPa or more, even more preferably 10 MPa or more, even more preferably 30 MPa or more, even more preferably 40 MPa or more, even more preferably 50 MPa or more, even more preferably 60 MPa or more, and particularly preferably 80 MPa or more. The upper limit of the shear relaxation modulus G ₁ (t=f ^-1 ) is not particularly specified, but even if the shear relaxation modulus G ₁ (t=f ^-1 ) is, for example, 1000 MPa or more, the bending strength of the laminated glass cannot be further improved. In one embodiment of the present invention, the shear relaxation modulus G ₁ (t=f ^-1 ) is 200 MPa or less.

The shear relaxation modulus _G2 (t=f ^-1 ) is preferably 0.30 MPa or more, more preferably 0.50 MPa or more, more preferably 0.75 MPa or more, more preferably 1.0 MPa or more, more preferably 1.5 MPa or more, even more preferably 2.0 MPa or more, and even more preferably 2.5 MPa or more. The upper limit of the shear relaxation modulus _G2 (t=f ^-1 ) is not particularly specified, but even if the shear relaxation modulus _G2 (t=f ^-1 ) is, for example, 1000 MPa or more, the bending strength of the laminated glass cannot be further improved. In one embodiment of the present invention, the shear relaxation modulus _G2 (t=f ^-1 ) is 10 MPa or less.

When the shear relaxation modulus G ₁ (t=f ^-1 ) and G ₂ (t=f ^-1 ) are equal to or greater than the lower limit and equal to or less than the upper limit, a laminated glass having sufficient bending strength is easily obtained even in applications where the glass is used at high temperatures for a long period of time. The shear relaxation modulus G ₁ (t=f ^-1 ) and G ₂ (t=f ^-1 ) can be adjusted to equal to or greater than the lower limit and equal to or less than the upper limit by, for example, changing the type or molecular weight of the resin contained in the resin material constituting the substrate layer, the additive content in the substrate layer, the type or vinyl alcohol unit content of the resin contained in the resin material constituting the adhesive layer, and/or the plasticizer content in the adhesive layer, and by adjusting the thickness of the substrate layer, the thickness of the adhesive layer, and/or the ratio of the thickness of the substrate layer to the thickness of the adhesive layer. Here, the term "resin material" in this specification means a resin composition consisting of one or more resins, or one or more resins and an optional component (e.g., a plasticizer or an additive, etc.) described later.

The shear relaxation modulus equivalent to the shear relaxation modulus after 24 hours or 10 years at 50° C. can be obtained by obtaining the shear relaxation modulus at a frequency corresponding to the reciprocal of the elapsed time. That is, the shear relaxation modulus equivalent to the shear relaxation modulus after 24 hours (=86,400 seconds) at 50° C. can be obtained by obtaining the shear relaxation modulus at 50° C. and a frequency of 1.2×10 ⁻⁵ Hz (≈1/86,400), and the shear relaxation modulus after 10 years (=31,536,000 seconds) at 50° C. can be obtained by obtaining the shear relaxation modulus at 50° C. and a frequency of 3.2×10 ⁻⁹ Hz (≈1/31,536,000). The shear relaxation modulus G ₁ (t=f ^-1 ) of the above-mentioned interlayer film at 50° C. and 1.2×10 ^-5 Hz corresponds to the shear relaxation modulus after 24 hours at 50° C., and the shear relaxation modulus G ₂ (t=f ^-1 ) of the above-mentioned interlayer film at 50° C. and 3.2×10 ^-9 Hz corresponds to the shear relaxation modulus after 10 years at 50° C. Laminated glass that requires long-term durability for architectural and structural applications, etc., preferably has sufficient strength (particularly bending strength) after 24 hours or 10 years at 50° C. The present inventors have found that such laminated glass can be obtained by sandwiching an interlayer film having G ₁ (t=f ^-1 ) and G ₂ (t=f ^-1 ) equal to or greater than specific values and including a laminate having a specific bending rigidity between two sheets of inorganic glass.

The shear relaxation modulus G ₁ (t=f ^-1 ) and G ₂ (t=f ^-1 ) can be determined using a shear viscoelasticity measuring device. For example, a sheet having a diameter of 8 mm and an arbitrary thickness of 5 mm or less is prepared from the interlayer film, and a rotational rheometer "ARES" (manufactured by Rheometric Scientific) is used to perform shear dynamic viscoelasticity measurement under the conditions of a frequency of 0.1 to 100 Hz, a measurement temperature of -50 to 250°C, a strain of <1%, and a temperature rise, to obtain a composite curve (master curve) of the shear storage modulus G'(f) and the shear loss modulus G''(f) at a reference temperature of 50°C. Using the time-temperature conversion rule, the shear relaxation modulus G ₁ (t=f ^-1 ) and G ₂ (t=f ^-1 ) can be determined from the obtained master curve according to the above formula (1).

In one embodiment of the present invention, the shear relaxation modulus of each of the m base layers and 2m adhesive layers included in the interlayer film is calculated using the thickness ratio of each of the layers (the ratio of the thickness of each layer in the interlayer film), and is expressed by the following formula (3):


[The shear relaxation modulus of each layer in formula (3) is the shear relaxation modulus at 50° C. and 1.2×10 ⁻⁵ Hz, and M is an integer of 1 to 7, preferably 1 to 3]
The shear relaxation modulus G ₁ (t) of the interlayer film is preferably 0.80 MPa or more, more preferably 1.0 MPa or more, more preferably 1.2 MPa or more, more preferably 1.5 MPa or more, more preferably 2.0 MPa or more, more preferably 4.0 MPa or more, more preferably 7.0 MPa or more, even more preferably 10 MPa or more, even more preferably 30 MPa or more, even more preferably 40 MPa or more, even more preferably 50 MPa or more, even more preferably 60 MPa or more, and particularly preferably 80 MPa or more. There is no particular upper limit for the shear relaxation modulus G ₁ (t). The shear relaxation modulus G ₁ (t) is, for example, 200 MPa or less.

The shear relaxation modulus G 2 (t) of the interlayer film represented by the above formula (3) [wherein the shear relaxation modulus of each layer in formula ( ₃ ) is the shear relaxation modulus at 50° C. and 3.2×10 ⁻⁹ Hz, and M is an integer of 1 to 7, preferably 1 to 3] is preferably 0.20 MPa or more, more preferably 0.30 MPa or more, more preferably 0.50 MPa or more, more preferably 0.75 MPa or more, more preferably 1.0 MPa or more, more preferably 1.5 MPa or more, even more preferably 2.0 MPa or more, and even more preferably 2.5 MPa or more. There is no particular upper limit for the shear relaxation modulus G ₂ (t). The shear relaxation modulus G ₂ (t) is, for example, 10 MPa or less.

When the shear relaxation moduli G ₁ (t) and G ₂ (t) are equal to or greater than the lower limit and equal to or less than the upper limit, a laminated glass having sufficient bending strength is likely to be obtained even in applications where the glass is used at high temperatures for a long period of time. The shear relaxation moduli G ₁ (t) and G ₂ (t) can be adjusted to equal to or greater than the lower limit and equal to or less than the upper limit by, for example, changing the type or molecular weight of the resin contained in the resin material constituting the substrate layer, the additive content in the substrate layer, the type or vinyl alcohol unit content of the resin contained in the resin material constituting the adhesive layer, and/or the plasticizer content in the adhesive layer, or by adjusting the thickness of the substrate layer, the thickness of the adhesive layer, and/or the ratio of the thickness of the substrate layer to the thickness of the adhesive layer.

The shear relaxation moduli G ₁ (t) and G ₂ (t) can be determined by the method described in the Examples below. The thickness of each layer may be determined by measuring any number of locations (e.g., 10 to 20 locations) with a thickness meter and averaging the values.

For an interlayer film having a shear relaxation modulus G ₁ (t=f ⁻¹ ) of 0.80 MPa or more and a shear relaxation modulus G ₂ (t=f ⁻¹ ) of 0.2 MPa or more, the values of the shear relaxation modulus G ₁ (t=f ⁻¹ ) and G ₂ (t=f ⁻¹ ) are equal to the values of the shear relaxation modulus G ₁ (t) and G ₂ (t), respectively.

When the interlayer film includes any structure as described above, the shear relaxation modulus of the layer having the structure is obtained, and the shear relaxation modulus G ₁ (t) and G ₂ (t) of the interlayer film are obtained. That is, for example, when the interlayer film is composed of a laminate having adhesive layers (II) on both sides of a base layer (I) having a design applied to a part of the base layer, the thickness ratio and shear relaxation modulus of the base layer (I) having the design applied are obtained, and the thickness ratio and shear relaxation modulus of the adhesive layer (II) are obtained, and the shear relaxation modulus G ₁ (t) and G ₂ (t) of the interlayer film are obtained from these values. In this case, the thickness of the base layer (I) may be determined by measuring any multiple locations (e.g., 10 to 20 locations) where the design is applied with a thickness meter and the average value of the values measured by measuring any multiple locations (e.g., 10 to 20 locations) where the design is not applied with a thickness meter.

In a preferred embodiment of the present invention, a laminated glass having an interlayer film sandwiched between two pieces of float glass having a thickness of 3.0 mm and a Young's modulus of 7.16×10 ⁴ MPa is subjected to a four-point bending test with a support distance of 0.3 m.
The following formula (4):
[ _In formula (4), _hs = 0.5 × ( _h1 + _h2 ) + _{hv , Is} = _hs2 × ^h1 × _h2 ÷ ( _h1 + _h2 ), _h1 and _h2 are the thicknesses of the two float glasses (unit: mm), _hv is the thickness of the interlayer (unit: mm), E is the Young's modulus of the float glass (unit: MPa), G(t = f-1) is the above _G1 (t = f ^{-1 )} (unit: MPa), and a is the distance between the supports in the four-point bending test (unit: m)]
The shear transfer coefficient _Γ1 of the interlayer film, represented by the following formula: is preferably 0.10 or more, more preferably 0.15 or more, more preferably 0.20 or more, more preferably 0.30 or more, more preferably 0.40 or more, more preferably 0.50 or more, even more preferably 0.60 or more, even more preferably 0.70 or more, and particularly preferably 0.80 or more.

The shear transfer coefficient Γ2 of the interlayer film represented by the above formula (4) [in formula (4), hs _{, Is} , _h1 , _h2 , _hv , E and a are as explained above, and G(t=f ^-1 ) is the above-mentioned _G2 (t=f ^-1 ) (unit: MPa) _] is preferably 0.02 or more, more preferably 0.03 or more, more preferably 0.10 or more, more preferably 0.15 or more, more preferably 0.20 or more, and more preferably 0.30 or more.

The shear transfer coefficient is a parameter indicating the rate at which the interlayer can contribute to the bending strength of the laminated glass, and takes a value of 0 or more and 1 or less. When a bending test of the laminated glass is performed, if the shear transfer coefficient is close to 1, the two inorganic glasses constituting the laminated glass deform as if they were one piece of inorganic glass while still being bonded via the interlayer, so that the apparent thickness (effective glass thickness described later) of the laminated glass as if it were one piece of inorganic glass increases, and the bending strength is improved. If the shear transfer coefficient is close to 0, the interlayer deforms between the two inorganic glasses, the bending strength is not fully exerted, and the apparent thickness decreases, so that it is necessary to design the inorganic glass thicker in order to obtain strength, and the weight of the laminated glass increases. The shear transfer coefficients Γ ₁ and Γ ₂ correspond to the shear transfer coefficients after 24 hours or 10 years at 50°C, respectively. Therefore, if the shear transfer coefficient Γ ₁ is equal to or greater than the lower limit, it indicates that the laminated glass can have a better bending strength after 24 hours at 50°C. Moreover, a shear transfer coefficient _Γ2 equal to or greater than the above lower limit indicates that the laminated glass can have superior bending strength after 10 years at 50°C.

The shear transfer coefficients _Γ1 and _Γ2 can be adjusted to be equal to or greater than the lower limit by, for example, adjusting the thickness of the substrate layer, the thickness of the adhesive layer, the ratio of the thickness of the substrate layer to the thickness of the adhesive layer, and/or the thickness of the intermediate film. The shear transfer coefficients _Γ1 and _Γ2 can be determined by the method described in the Examples below.

The thickness of the intermediate film is preferably 0.30 mm or more, more preferably 0.40 mm or more, even more preferably 0.45 mm or more, and is preferably 3.00 mm or less, more preferably 2.50 mm or less, more preferably 2.30 mm or less, even more preferably 2.00 mm or less, and particularly preferably 1.60 mm or less, provided that the substrate layer (I) and adhesive layer (II) in the laminate satisfy the thickness ranges of each layer described below. When the thickness of the intermediate film is equal to or greater than the lower limit and equal to or less than the upper limit, the intermediate film is easily provided as a roll, and an intermediate film having the desired handling properties, transparency, penetration resistance, and bending strength is easily obtained. The thickness of the intermediate film can be measured with a thickness meter, and the average value measured at multiple locations (for example, 10 to 20 locations) may be used.

<Laminate>
In the present invention, the compound represented by the following formula (2):
The flexural rigidity of the laminate at 25° C. is 6 N·mm or more and 70 N·mm or less. If the flexural rigidity of the laminate at 25° C. is less than 6 N·mm or more than 70 N·mm, it is difficult for the interlayer film to have good handleability during the production of laminated glass.

The bending rigidity is preferably 8 N·mm or more, more preferably 10 N·mm or more, more preferably 12 N·mm or more, more preferably 14 N·mm or more, more preferably 20 N·mm or more, even more preferably 25 N·mm or more, and particularly preferably 31 N·mm or more. When the bending rigidity is equal to or more than the lower limit, better handleability during the production of laminated glass is easily obtained.
The bending stiffness is preferably 68 N·mm or less, more preferably 65 N·mm or less, even more preferably 63 N·mm or less, and particularly preferably 61 N·mm or less. When the bending stiffness is equal to or less than the upper limit, the laminate and the interlayer film can be more easily wound around a relatively thin winding core (e.g., a winding core having a diameter of 6 inches (about 15.24 cm)), and the laminate and the interlayer film are less likely to have a curling tendency after being unwound from the roll.

The following formula (5):

The bending stiffness of the laminate at 50°C represented by is preferably 3 N mm or more, more preferably 5 N mm or more, more preferably 11 N mm or more, more preferably 12 N mm or more, more preferably 13 N mm or more, more preferably 18 N mm or more, even more preferably 20 N mm or more, particularly preferably 30 N mm or more, and is preferably 65 N mm or less, more preferably 63 N mm or less, even more preferably 61 N mm or less, particularly preferably 60 N mm or less. When the bending stiffness is equal to or greater than the lower limit, excellent handleability is easily obtained during laminated glass production even at high temperatures. When the bending stiffness is equal to or less than the upper limit, the laminate and the interlayer can be more easily wound around a relatively thin winding core even at high temperatures, and the laminate and the interlayer are less likely to have a curling tendency after being unwound from the roll.

The bending rigidity at 25°C and the bending rigidity at 50°C of the laminate can be adjusted to be equal to or greater than the lower limit and equal to or less than the upper limit, for example, by laminating the base material layer (I) and the adhesive layer (II) at an appropriate thickness ratio and/or by adjusting the bending modulus of each layer.
The flexural rigidity of the laminate at 25°C can be determined by the method described in the Examples below, and the flexural rigidity of the laminate at 50°C can be determined by the same method. The flexural modulus of the laminate at 25°C or 50°C can also be determined from the known Young's modulus of the resin material constituting the base layer (I) and the resin material constituting the adhesive layer (II), and the flexural rigidity of the laminate at 25°C or 50°C can also be determined using the above formula (2) or (5). In the present invention, the Poisson's ratio of the laminate is 0.38.

The flexural modulus of the laminate at 25°C is preferably 30 MPa or more, more preferably 100 MPa or more, even more preferably 200 MPa or more, and particularly preferably 220 MPa or more, from the viewpoint of easily obtaining the desired flexural rigidity. There is no particular upper limit to the flexural modulus. The flexural modulus is usually 1800 MPa or less.

The flexural modulus of the laminate at 50°C is preferably 20 MPa or more, more preferably 100 MPa or more, even more preferably 200 MPa or more, and particularly preferably 220 MPa or more, from the viewpoint of easily obtaining the desired flexural rigidity. There is no particular upper limit to the flexural modulus. The flexural modulus is usually 1600 MPa or less.

The flexural modulus at 25°C and the flexural modulus at 50°C of the laminate can be adjusted to above the lower limit, for example, by increasing the ratio T(I)/2T(II) of the thickness T(I) of the base layer (I) to the thickness T(II) of the adhesive layer (II).
The flexural modulus of the laminate at 25° C. can be experimentally measured by the method described in the Examples below, and the flexural modulus of the laminate at 50° C. can be determined in a similar manner. The flexural modulus of the laminate at 25° C. and at 50° C. can also be determined using the known Young's modulus of the resin material constituting the base layer (I) and the resin material constituting the adhesive layer (II).

The tensile storage modulus of the laminate measured by dynamic tensile viscoelasticity measurement at 25°C, a frequency of 1 Hz, and a strain of <1% is preferably 0.1 to 1800 MPa, more preferably 1 to 1600 MPa, and even more preferably 10 to 1500 MPa. If the tensile storage modulus is equal to or greater than the lower limit, the laminate can be easily wound up without breaking even if the adhesive layer (II) is thin. If the tensile storage modulus is equal to or less than the upper limit, it is easy to prevent the laminate from cracking due to stress generated during the production of laminated glass, and it is easy to obtain laminated glass with excellent appearance. The tensile storage modulus can be measured by a viscoelasticity measuring device, for example, by preparing a sheet of 20 mm length x 5 mm width x 0.2 mm thickness and performing tensile dynamic viscoelasticity measurement using a viscoelasticity spectrometer "Rheogel-E4000" (manufactured by UBM Co., Ltd.) under measurement conditions of a frequency of 1 Hz and a measurement temperature of -50 to 250°C. The tensile storage modulus can be adjusted within the above range, for example, by adjusting the amount of plasticizer added in the adhesive layer (II), adjusting the vinyl alcohol unit content of the polyvinyl acetal resin, and/or adjusting the thickness ratio between the substrate layer (I) and the adhesive layer (II).

In a preferred embodiment of the present invention, the thickness of the substrate layer (I) in the laminate is greater than the thickness of either of the two adhesive layers (II).
In a preferred embodiment of the present invention, the thickness of the base layer (I) in the laminate is greater than the total thickness of the two adhesive layers (II).
In these embodiments, the interlayer is more likely to have the desired shear relaxation modulus G ₁ (t=f ⁻¹ ) and G ₂ (t=f ⁻¹ ) as well as the desired penetration resistance, and the laminate is more likely to have the desired bending stiffness.

The thickness of one laminate is preferably 0.95 mm or less, more preferably 0.90 mm or less, more preferably 0.85 mm or less, even more preferably 0.80 mm or less, and particularly preferably 0.76 mm or less, provided that the substrate layer (I) and the adhesive layer (II) satisfy the thickness ranges of each layer described below. When the thickness of one laminate is equal to or less than the upper limit, it is easy to provide a laminate having the thickness ratio as a roll, and it is easy to obtain a laminate having good handleability, transparency, and shear transfer coefficient. In addition, the thickness of one laminate is preferably 0.30 mm or more, more preferably 0.40 mm or more, and even more preferably 0.45 mm or more, provided that the thickness ranges of each layer described above are satisfied. When the thickness of one laminate is equal to or more than the lower limit, it is easy to obtain a laminate that provides the penetration resistance required for laminated glass.

<<Base material layer (I)>>
The hard resin contained in the substrate layer (I) provides the intermediate film with the desired shear relaxation modulus G ₁ (t=f ⁻¹ ) and G ₂ (t=f ⁻¹ ) and provides the laminate with the desired bending strength. There is no particular limitation as long as it provides rigidity. Specific examples of hard resins include acrylic resins, polycarbonate resins, polyester resins, polystyrene resins, polyolefin resins, polymethylpentene resins, cyclic polyolefin resins, acrylonitrile-butadiene-styrene resins, etc. Among these, from the viewpoint of easily achieving a balance between transparency, penetration resistance, and economic efficiency, acrylic resins or polycarbonate resins are preferred, and from the viewpoint of superior penetration resistance, polycarbonate resins are more preferred. In a preferred embodiment of the present invention, the substrate layer (I) contains a polycarbonate resin as a hard resin. These hard resins may be used alone or in combination of two or more. This is also fine.
In addition, the resin material constituting the base layer (I) may contain additives such as antioxidants, heat deterioration inhibitors, ultraviolet absorbers, light stabilizers, lubricants, release agents, polymer processing agents, etc., as long as they are not contrary to the spirit of the present invention. Additives such as auxiliary agents, antistatic agents, flame retardants, dyes, pigments, light diffusing agents, organic dyes, delustering agents, impact resistance modifiers and fluorescent substances are contained alone or in combination of two or more. Good too.

(Polyester resin)
The polyester resin is not particularly limited. Specific examples include polyethylene terephthalate (PET), polyhydroxypropyl methacrylate, polyhydroxyethyl methacrylate, etc., and among these, PET is preferred. The PET may be modified PET, and a preferred example of the modified PET is cyclohexane dimethylene modified PET (PETG). Commercially available polyester resins may also be used, and examples of such commercially available products include CLAPET (manufactured by Kuraray Co., Ltd.), NOVAPEX (manufactured by Mitsubishi Chemical Corporation), and SKYGREEN PETG (manufactured by SK Chemical Co., Ltd., Korea).

(Polystyrene resin)
The polystyrene resin is not particularly limited, but high impact polystyrene (HIPS) is preferable. Commercially available polystyrene resins may be used, and examples of such commercially available products include PSJ-polystyrene SX100 and SX300 (manufactured by PS Japan Co., Ltd.).

(Polyolefin resin)
The polyolefin resin is not particularly limited. Specific examples include polyethylene, polypropylene, polybutene-1, polyhexene-1, poly-3-methyl-butene-1, poly-4-methyl-pentene-1, copolymers of ethylene with one or more α-olefins having 3 to 20 carbon atoms (e.g., propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 3-methyl-1-butene, 4-methyl-1-pentene, 6-methyl-1-heptene, isooctene, isooctane, decadiene, etc.), ethylene/propylene/diene copolymers (EPDM), ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, etc. The polyolefin resin may be a modified polyolefin, for example, a polyolefin resin modified with maleic anhydride or the like. A commercially available polyolefin resin may be used, or a commercially available product processed into a sheet shape may be used. An example of a commercially available sheet-like product is Super Pureray (manufactured by Idemitsu Unitech Co., Ltd.).

(Polymethylpentene resin)
The polymethylpentene resin is not particularly limited, and commercially available products can be preferably used. Examples of such commercially available products include TPX "RT18" and TPX "RT31" (manufactured by Mitsui Chemicals, Inc.).

(Cyclic polyolefin resin)
The cyclic polyolefin resin is not particularly limited, and commercially available products can be preferably used. Examples of such commercially available products include "TOPAS" (Topas) produced by TOPAS ADVANCED POLYMERS GmbH in Germany and sold by Polyplastics Co., Ltd. in Japan, "Arton" manufactured and sold by JSR Corporation, "ZEONOR" and "ZEONEX" manufactured and sold by Nippon Zeon Co., Ltd., and "Apel" manufactured and sold by Mitsui Chemicals, Inc.

(Acrylonitrile-butadiene-styrene resin)
The acrylonitrile-butadiene-styrene resin is not particularly limited, and commercially available products can be preferably used. Examples of such commercially available products include Santac AT-05 and Clalastic SXH-330 (both manufactured by Nippon A&L Co., Ltd.), Toyolac 500 and 700 (manufactured by Toray Industries, Inc.), PA-756 (manufactured by Chimei Corporation), and HR181 (manufactured by Kumho Petrochemical Co., Ltd.). The acrylonitrile-butadiene-styrene resin may be copolymerized with other resins. Examples of such copolymers include methyl methacrylate-acrylonitrile-butadiene-styrene quaternary copolymers (MABS), and examples of commercially available MABS products include Denka CL polymer, Denka TE polymer, and Denka TP polymer (all manufactured by Denki Kagaku Kogyo Co., Ltd.).

(Acrylic resin)
The acrylic resin includes one or more methacrylic resins (PM). The methacrylic resin is a homopolymer or copolymer containing structural units derived from one or more methacrylic acid hydrocarbon esters (hereinafter also simply referred to as "methacrylic acid esters"), preferably including methyl methacrylate (MMA).
The hydrocarbon group in the methacrylic acid ester may be a non-cyclic aliphatic hydrocarbon group such as a methyl group, an ethyl group, or a propyl group, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group such as a phenyl group.
From the viewpoint of transparency, the content of structural units derived from methacrylic acid esters in the methacrylic resin is preferably 50% by mass or more, more preferably 80% by mass or more, particularly preferably 90% by mass or more, based on all structural units constituting the methacrylic resin. It may be 100% by mass.

The methacrylic resin may contain structural units derived from one or more other monomers other than methacrylic acid esters. Examples of other monomers include acrylic acid esters such as methyl acrylate (MA), ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, dodecyl acrylate, stearyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, cyclohexyl acrylate, 2-methoxyethyl acrylate, 3-methoxybutyl acrylate, trifluoromethyl acrylate, trifluoroethyl acrylate, pentafluoroethyl acrylate, glycidyl acrylate, allyl acrylate, phenyl acrylate, toluyl acrylate, benzyl acrylate, isobornyl acrylate, and 3-dimethylaminoethyl acrylate. Among these, from the viewpoint of availability, MA, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, and tert-butyl acrylate are preferred, MA and ethyl acrylate are more preferred, and MA is particularly preferred. When the methacrylic resin contains structural units derived from other monomers, the content thereof is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 2% by mass or less, based on the total structural units constituting the methacrylic resin.

Methacrylic resins can be obtained by polymerizing one or more methacrylic acid esters, preferably including MMA, and other monomers as necessary. When multiple types of monomers are used, the multiple types of monomers are usually mixed to prepare a monomer mixture, and then polymerization is carried out. There are no particular limitations on the polymerization method, and from the viewpoint of productivity, radical polymerization methods such as bulk polymerization, suspension polymerization, solution polymerization, and emulsion polymerization are preferred.

The weight average molecular weight (Mw) of the methacrylic resin is preferably 40,000 to 500,000. When the Mw is 40,000 or more, the base layer (I) tends to have better scratch resistance and heat resistance. When the Mw is 500,000 or less, the base layer (I) tends to have excellent moldability.
In this specification, unless otherwise specified, "Mw" is a value calculated as standard polystyrene measured using gel permeation chromatography (GPC).

The glass transition temperature of the methacrylic resin is not particularly limited. The glass transition temperature is preferably 115 to 135°C, more preferably 120 to 130°C. If the glass transition temperature is equal to or higher than the lower limit, deformation of the base layer (I) during the production of the laminated glass is easily prevented. If the glass transition temperature is equal to or lower than the upper limit, defects in appearance such as cracks in the base layer (I) are unlikely to occur.

The substrate layer (I) may be made of a methacrylic resin as described above, or may be made of a methacrylic resin composition containing one or more other polymers as necessary, as long as the purpose and effect of the present invention are not hindered. The other polymers are not particularly limited, and include other thermoplastic resins such as styrene-maleic anhydride copolymer, polyolefins such as polyethylene and polypropylene, polyamide, polyphenylene sulfide, polyether ether ketone, polyester, polysulfone, polyphenylene oxide, polyimide, polyetherimide, and polyacetal; and thermosetting resins such as phenolic resin, melamine resin, silicone resin, and epoxy resin. When the substrate layer (I) is made of a methacrylic resin composition, the content of the other polymer in the methacrylic resin composition is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 2% by mass or less, from the viewpoint of easily increasing the glass transition temperature. In a preferred embodiment, the glass transition temperature of the methacrylic resin composition is preferably 115 to 135°C, more preferably 120 to 130°C. In this embodiment, the glass transition temperature of the other polymer may be outside the range of 115-135°C.

The methacrylic resin composition may contain various additives as necessary. Examples of additives include antioxidants, heat deterioration inhibitors, ultraviolet absorbers, light stabilizers, lubricants, release agents, polymer processing aids, antistatic agents, flame retardants, dyes, pigments, light diffusing agents, organic dyes, matting agents, impact resistance modifiers (e.g., core-shell particles and block copolymers, etc.), and fluorescent materials. The content of the additives can be appropriately set within a range that does not interfere with the purpose and effect of the present invention. For example, the content of the antioxidant is preferably 0.01 to 1 part by mass, the content of the ultraviolet absorber is preferably 0.01 to 3 parts by mass, the content of the light stabilizer is preferably 0.01 to 3 parts by mass, the content of the lubricant is preferably 0.01 to 3 parts by mass, and the content of the dye or pigment is preferably 0.01 to 3 parts by mass, relative to 100 parts by mass of the resin contained in the base layer (I).

As the core-shell particles, core-shell type rubber particles, for example, core-shell type impact modifiers containing acrylic rubber or diene rubber as the core component are preferred.

The tensile storage modulus of the methacrylic resin composition measured by dynamic tensile viscoelasticity measurement at 25 to 50°C, a frequency of 1 Hz, and a strain of <1% is usually 1 to 4,000 MPa, preferably 500 to 3,500 MPa, more preferably 1000 to 3,000 MPa, and even more preferably 1,500 to 2,500 MPa. When the tensile storage modulus is equal to or greater than the lower limit, it is easy to increase the tensile storage modulus of the base layer (I). The tensile storage modulus can be measured by a viscoelasticity measuring device, for example, by preparing a sheet of 20 mm length x 5 mm width x 0.4 mm thickness and performing tensile dynamic viscoelasticity measurement using a viscoelasticity spectrometer "Rheogel-E4000" (manufactured by UBM Co., Ltd.) under the measurement conditions of a frequency of 1 Hz, a measurement temperature of -50 to 250°C, and a strain of <1%. The tensile storage modulus can be adjusted to within the above range, for example, by reducing the amount of core-shell rubber particles contained in the methacrylic resin composition.

The melt flow rate (hereinafter abbreviated as "MFR") of the methacrylic resin composition is not particularly limited. The MFR is preferably 1 to 10 g/10 min, more preferably 1.2 to 7 g/10 min, and particularly preferably 1.5 to 4 g/10 min. Unless otherwise specified, the MFR of the methacrylic resin composition is a value measured using a melt indexer at a temperature of 230°C and a load of 3.8 kg. For example, the MFR can be adjusted to within the above range by adjusting the weight average molecular weight of the methacrylic resin and/or using additives.

The film-forming temperature and melt viscosity of the methacrylic resin composition are not particularly limited. The melt viscosity is preferably 200 to 5000 Pa·s at a temperature of 220 to 240°C and a shear rate of 60 s ^-1 . The melt viscosity is measured, for example, using a Toyo Seiki Capillograph (Type 1C, temperature range: 60 to 400°C, barrel diameter: 9.55 mmφ) in accordance with JIS K7199. When forming a film by co-extrusion with the adhesive layer (II) described below, it is preferable that the film can be formed at 230°C or less. The reason for this is that, for example, when the resin material constituting the adhesive layer contains a polyvinyl acetal resin, if the film-forming temperature of the methacrylic resin composition is 230°C or less, the thermal deterioration of the polyvinyl acetal resin can be suppressed, and a laminate with good appearance can be easily obtained. When the melt viscosity at 230°C and a shear rate of 60 s ^-1 is preferably 200 to 4500 Pa·s, more preferably 500 to 4000 Pa·s, and particularly preferably 1000 to 3500 Pa·s, the ratio between the melt viscosity of the methacrylic resin composition and the melt viscosity of the polyvinyl acetal resin material can be adjusted by also adjusting the melt viscosity of the polyvinyl acetal resin material, which makes it easier to further suppress thermal degradation of the polyvinyl acetal resin.

The method for producing the methacrylic resin composition is not particularly limited, and known methods for producing methacrylic resin compositions can be widely adopted. Examples of the mixing method include a melt mixing method and a solution mixing method. In the melt mixing method, a single-axis or multi-axis kneader; an open roll, a Banbury mixer, a kneader, or the like, can be used, and melt kneading can be performed under an inert gas atmosphere such as nitrogen gas, argon gas, or helium gas, as necessary. In the solution mixing method, the methacrylic resin and other polymers can be dissolved in an organic solvent such as toluene, tetrahydrofuran, or methyl ethyl ketone and mixed.
In addition, the method of mixing the methacrylic resin with the other polymer and/or additive is not particularly limited. For example, the other polymer and/or additive may be added during or after the polymerization of the methacrylic resin, or the methacrylic resin or the methacrylic resin and the additive may be added during or after the polymerization of the other polymer.

Commercially available methacrylic resin compositions may be used. Examples of such commercially available products include "Parapet GF," "Parapet GR-00100," and "Parapet GR-H60" (all manufactured by Kuraray Co., Ltd.).

(Polycarbonate resin)
The polycarbonate resin is not particularly limited. As the polycarbonate resin, known resins obtained by reacting a polyfunctional hydroxy compound with a carbonate ester-forming compound can be used alone or in combination of two or more. Examples of such resins include aromatic polycarbonate resins, aliphatic polycarbonate resins, and branched polycarbonate resins obtained by branching these resins.
Examples of aromatic polycarbonate resins include those derived from 2,2-bis(4-oxyphenyl)propane (also known as bisphenol A) and resins containing a polycarbonate component made of poly(ester carbonate). These resins are copolyesters having repeating carbonate, carboxylate and aromatic carbocyclic groups in a linear polymer chain.
Examples of aliphatic polycarbonate resins include aliphatic polycarbonate resins made of carbonic acid and aliphatic diols or alicyclic diols, which may be copolymers containing structural units derived from a plurality of aliphatic diols or alicyclic diols, or copolymers having structural units derived from aliphatic compounds, such as aliphatic diols or alicyclic diols, and structural units derived from the aromatic compounds in the molecular chain.

Examples of the polyfunctional hydroxy compound include linear aliphatic diols, branched aliphatic diols, alicyclic diols, other diols, and aromatic dihydroxy compounds. The polyfunctional hydroxy compounds may be used alone or in combination of two or more. There are no particular limitations on these compounds, but aromatic dihydroxy compounds are preferred from the viewpoint of obtaining better heat resistance or mechanical strength.

Examples of aromatic dihydroxy compounds include 4,4'-dihydroxybiphenyls, bis(hydroxyphenyl)alkanes, bis(4-hydroxyphenyl)ethers, bis(4-hydroxyphenyl)sulfides, bis(4-hydroxyphenyl)sulfoxides, bis(4-hydroxyphenyl)sulfones, bis(4-hydroxyphenyl)ketones, bis(hydroxyphenyl)fluorenes, dihydroxy-p-terphenyls, dihydroxy-p-quaterphenyls, bis(hydroxyphenyl)pyrazines, bis(hydroxyphenyl)menthanes, bis[2-(4-hydroxyphenyl)-2-propyl]benzenes, dihydroxynaphthalenes, and dihydroxybenzenes.

Among these, from the viewpoint of obtaining superior heat resistance or mechanical strength, 2,2-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl)diphenylmethane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3-phenylphenyl)propane, 4,4'-dihydroxybiphenyl, bis(4-hydroxyphenyl)sulfone, 2,2-bis(3,5-dibromo-4-hydro bis(4-hydroxyphenyl)propane, 3,3-bis(4-hydroxyphenyl)pentane, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, bis(4-hydroxyphenyl)ether, 4,4'-dihydroxybenzophenone, 2,2-bis(4-hydroxy-3-methoxyphenyl)1,1,1,3,3,3-hexafluoropropane, α,ω-bis[3-(2-hydroxyphenyl)propyl]polydimethylsiloxane, resorcin, and 2,7-dihydroxynaphthalene are preferred, with 2,2-bis(4-hydroxyphenyl)propane being more preferred.

The carbonate ester-forming compound is not particularly limited. Examples of the carbonate ester-forming compound include various dihalides such as phosgene; haloformates such as chloroformates; and carbonate ester compounds such as bisarylcarbonates. The carbonate ester-forming compounds may be used alone or in combination of two or more.

In addition to polycarbonate structural units, the polycarbonate resin may contain one or more structural units derived from polyester structural units, polyurethane structural units, polyether structural units, polystyrene structural units, polysiloxane structural units, monomers, oligomers or polymers having phosphorus atoms, etc.

The method for producing the polycarbonate resin is not particularly limited, and any conventionally known production method can be used. In addition, a commercially available product may be used as the polycarbonate resin. Examples of such commercially available products include "SDPOLYCA 301-4" (manufactured by Sumika Polycarbonate Co., Ltd., melt volume flow rate (hereinafter abbreviated as "MVR") at 300°C and 1.2 kg load: 4 cm ³ /10 min), "SDPOLYCA 301-6" (manufactured by Sumika Polycarbonate Co., Ltd., MVR: 6 cm ³ /10 min), "SDPOLYCA 301-10" (manufactured by Sumika Polycarbonate Co., Ltd., MVR: 6 cm ³ /10 min), "SDPOLYCA PCX" (manufactured by Sumika Polycarbonate Co., Ltd.), "Iupilon H-3000" (manufactured by Mitsubishi Engineering Plastics Corporation, MVR: 28 cm ³ /10 min), and "Iupilon S-2000" (manufactured by Mitsubishi Engineering Plastics Corporation, MVR: 9 cm ³ /10 min).

The viscosity average molecular weight of the polycarbonate resin is not particularly limited. From the viewpoint of film-forming properties and mechanical properties, the viscosity average molecular weight is usually 10,000 to 60,000, preferably 15,000 to 35,000, and more preferably 18,000 to 30,000. When producing such a polycarbonate resin, the viscosity average molecular weight can be adjusted to within the above range by using a molecular weight regulator or catalyst, etc., as necessary. In addition, two or more polycarbonate resins with different viscosity average molecular weights may be prepared in advance and blended to adjust to the desired viscosity average molecular weight.

The MVR of the polycarbonate resin is not particularly limited. The MVR at 300° C. and a load of 1.2 kg is usually 1 to 200 cm ³ /10 min. Here, the MVR is measured in accordance with ISO1133. From the viewpoint of moldability and penetration resistance, the MVR of the polycarbonate resin is preferably 2 to 30 cm ³ /10 min, more preferably 3 to 10 cm ³ /10 min. When producing such a polycarbonate resin, the MVR can be adjusted to within the above range by using a molecular weight regulator or a catalyst, etc., as necessary. In addition, two or more polycarbonate resins with different MVRs may be prepared in advance and blended to adjust the desired MVR.

The melt viscosity of the polycarbonate resin is not particularly limited, but is usually 200 to 6000 Pa·s at a temperature of 260 to 300°C and a shear rate of 60 s ^-1 . The melt viscosity is measured in accordance with JIS K7199, for example, using a Toyo Seiki Capillograph (Type 1C) (temperature range: 60 to 400°C, barrel diameter: 9.55 mmφ). The melt viscosity is preferably 1200 Pa·s or less, more preferably 1050 Pa·s or less, at a heating temperature of 280°C. When the melt viscosity is equal to or less than the above-mentioned preferred value, the resin in the pipe or die or in the polymer filter flows favorably and is unlikely to have a stagnant portion, so that scorching or gelling is unlikely to occur, and the appearance defect of the laminate is unlikely to occur. In addition, since die streaks are unlikely to occur, it is easy to suppress the deterioration of the haze of the laminate. On the other hand, the melt viscosity can be lowered by simply increasing the temperature, but this is not preferable because the resin is likely to thermally deteriorate and yellow.

The glass transition temperature of the polycarbonate resin is not particularly limited. The glass transition temperature is preferably 100 to 180°C, more preferably 110 to 160°C. When the glass transition temperature is equal to or higher than the lower limit, deformation of the substrate (I) during the production of the laminated glass is easily prevented. When the glass transition temperature is equal to or lower than the upper limit, the occurrence of defects such as sink marks during extrusion molding due to the high melt viscosity of the polycarbonate resin is easily prevented. The glass transition temperature can be adjusted to within the above range, for example, by adjusting the viscosity average molecular weight of the polycarbonate resin and/or the compounding ratio of polycarbonate resins with different viscosity average molecular weights.

The Charpy impact strength of the polycarbonate resin is not particularly limited. From the viewpoint of the penetration resistance when a flying object hits the laminated glass, the Charpy impact strength is preferably 5 kJ/m ² or more, more preferably 10 kJ/m ² or more, even more preferably 30 kJ/m ² or more, and particularly preferably 60 kJ/m ² or more. In this specification, the Charpy impact strength is a value obtained by notching a 3 mm thick test piece in accordance with ISO179 and measuring the notched Charpy impact strength at 23°C. The Charpy impact strength can be adjusted to be equal to or higher than the lower limit by, for example, adjusting the viscosity average molecular weight distribution of the polycarbonate resin and/or the combination of the polyfunctional hydroxy compound and the carbonate ester forming compound.

The total light transmittance of the polycarbonate resin is preferably 70% or more, more preferably 80% or more, even more preferably 85% or more, and particularly preferably 89% or more. If the total light transmittance is equal to or more than the lower limit, the transparency tends to be high when the substrate layer (I) is used in the thickness range described below, and the transparency of the resulting laminated glass also tends to be high. The total light transmittance can be measured by a haze meter according to the measurement method described in JIS K7361-1 using a molded product having a thickness of, for example, 3 mm or less (for example, 3 mm) obtained by press molding the polycarbonate resin. The total light transmittance can be adjusted to equal to or more than the lower limit by adjusting the refractive index of the polycarbonate resin by selecting, for example, a multifunctional hydroxy compound and a carbonate ester-forming compound.

The substrate layer (I) may be made of the polycarbonate resin as described above, or may be made of a polycarbonate resin composition containing additives as necessary, provided that the additives do not impede the object and effect of the present invention.
Examples of additives include antioxidants, heat deterioration inhibitors, ultraviolet absorbers, light stabilizers, lubricants, release agents, polymer processing aids, antistatic agents, flame retardants, dyes, pigments, light diffusing agents, organic dyes, matting agents, impact resistance modifiers, and fluorescent materials. When additives are used, one may be used alone, or two or more may be used in combination. When additives are used, the amount of the additive is preferably 5% by mass or less, more preferably 3% by mass or less, based on the total mass of the polycarbonate resin composition.

When the substrate layer (I) is formed by co-extrusion with the adhesive layer (II) described below, the viscosity may be adjusted by adding more than 5% by mass of an antiplasticizer or resin additive so that the melt viscosity is within the above range at a lower temperature. Examples of such compositions include a composition in which a polycarbonate resin is alloyed with an aromatic polyester, and a composition containing a polycarbonate resin and a plasticizer or antiplasticizer. The compounding ratio may be appropriately adjusted depending on the resin material constituting the adhesive layer (II). For example, when a polyvinyl acetal resin is used as the resin material constituting the adhesive layer (II), it is preferable to contain 85 to 99 parts by mass of polycarbonate resin and 15 to 1 part by mass of plasticizer or antiplasticizer.

Examples of aromatic polyesters used in alloys with polycarbonate resins include polycondensates of aromatic dicarboxylic acid components and diol components. Representative aromatic dicarboxylic acid components include terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid. Other dicarboxylic acid components may also be used in the polycondensation, and examples of such dicarboxylic acid components include oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, neopentyl acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyl ether dicarboxylic acid, and p-oxybenzoic acid. These may be used alone or in combination of two or more.
Representative diol components include ethylene glycol, diethylene glycol, triethylene glycol, and cyclohexanedimethanol, etc. Other diol components include propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, neopentyl glycol, polyalkylene glycol, 1,4-cyclohexanedimethanol, glycerin, pentaerythritol, trimethylol, methoxypolyalkylene glycol, etc. These can be used alone or in combination of two or more.

A typical example of an aromatic polyester is polyethylene terephthalate (PET), which is a polycondensation product of terephthalic acid and ethylene glycol. Copolymer polyesters using terephthalic acid and ethylene glycol with other dicarboxylic acid components and/or other diol components are also preferred. Another typical example of an aromatic polyester is polybutylene terephthalate (PBT), which is a polycondensation product of terephthalic acid or dimethyl terephthalate with 1,4-butanediol. Copolymer polyesters using terephthalic acid and 1,4-butanediol with other dicarboxylic acid components and/or other diol components are also preferred. Among them, a copolymer polyester (PCTG) in which cyclohexanedimethanol (1.4-CHDM) is used as a part of the ethylene glycol in PET (preferably 55 to 75 mol %, preferably 50 to 75 mol %, based on the total number of moles of ethylene glycol used in polycondensation), a copolymer polyester (PCTG) in which isophthalic acid is used as a part of the terephthalic acid in PBT (preferably 10 to 30 mol %, based on the total number of moles of terephthalic acid used in polycondensation), and a combination of these are preferred. These copolymer polyesters can be completely compatible and polymer-alloyed by melt-blending with polycarbonate resin. This polymer alloying can also effectively reduce the film-forming temperature and melt viscosity.

The plasticizer is not particularly limited, and examples thereof include phosphate ester compounds such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, tris(2-ethylhexyl)phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, and 2-ethylhexyl diphenyl phosphate; phosphite compounds corresponding to these phosphate ester compounds; phthalate ester compounds such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, bis(2-ethylhexyl phthalate), diisodecyl phthalate, butyl benzyl phthalate, diisononyl phthalate, and ethyl phthalyl ethyl glycolate; tris(2-ethylhexyl) trimellitate, and other triphosphate ester compounds. Examples of the compound include trimellitic acid ester compounds; aliphatic dibasic acid ester compounds such as dimethyl adipate, dibutyl adipate, diisobutyl adipate, bis(2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, bis(butyldiglycol) adipate, bis(2-ethylhexyl) azelate, dimethyl sebacate, dibutyl sebacate, bis(2-ethylhexyl) sebacate, and diethyl succinate; polyester compounds containing aliphatic dibasic acid units contained in these aliphatic dibasic acid ester compounds; ricinoleic acid ester compounds such as methyl acetyl ricinoleate; acetate compounds such as triacetin and octyl acetate; and sulfonamide compounds such as N-butylbenzenesulfonamide. Among these, phosphate ester compounds, especially cresyl diphenyl phosphate (CDP) and tricresyl phosphate (TCP), are preferred because of their good compatibility with polycarbonate resin and the good transparency of the resin after compatibility.

There are no particular limitations on the antiplasticizer, and industrially available biphenyl compounds and terphenyl compounds can be used. Biphenyl compounds are compounds in which two benzene rings are bonded, and terphenyl compounds are compounds in which three benzene rings are bonded. Polycaprolactone can also be used as the antiplasticizer.

The method for producing the polycarbonate resin composition is not particularly limited, and any of the known methods for producing polycarbonate resin compositions can be widely used. Examples of such production methods include a method in which the polycarbonate resin and additives to be mixed as necessary are premixed using various mixers such as a tumbler or Henschel mixer, and then melt-kneaded using a mixer such as a Banbury mixer, roll, Brabender, single-screw kneading extruder, twin-screw kneading extruder, or kneader. The melt-kneading temperature is not particularly limited, and may be appropriately selected depending on the type of polycarbonate resin. The melt-kneading temperature is usually 220 to 320°C.

The properties of the polycarbonate resin composition, such as viscosity average molecular weight, MVR, glass transition temperature, and Charpy impact strength, are not particularly limited. It is preferable that the polycarbonate resin composition has properties similar to those of the polycarbonate resin described above.

The tensile storage modulus of the polycarbonate resin composition measured by dynamic tensile viscoelasticity measurement at 25 to 50°C, a frequency of 1 Hz, and a strain of <1% is usually 800 to 4,000 MPa, preferably 1,000 to 3,500 MPa, more preferably 1,300 to 3,000 MPa, and even more preferably 1,500 to 2,500 MPa. If the tensile storage modulus is equal to or greater than the lower limit, the tensile storage modulus of the base layer (I) is easily increased. The tensile storage modulus can be measured by the same method as the method for measuring the tensile storage modulus of the methacrylic resin composition described above. The tensile storage modulus can be adjusted to within the above range, for example, by selecting bisphenol A as a raw material for the polycarbonate resin.

The film-forming temperature and melt viscosity of the polycarbonate resin composition are not particularly limited, but when the film is formed by co-extrusion with the adhesive layer (II) described later, it is preferable that the film can be formed at a lower temperature. For example, when a polyvinyl acetal resin is used as the resin material constituting the adhesive layer, if the film-forming temperature of the polycarbonate resin composition is 230° C. or less, the thermal deterioration of the polyvinyl acetal resin can be suppressed, and a laminate with good appearance can be easily obtained. From the viewpoint of easily adjusting the ratio of the melt viscosity of the polycarbonate resin composition to the melt viscosity of the polyvinyl acetal resin material within a desired range and thus easily suppressing thermal degradation of the polyvinyl acetal resin, the melt viscosity of the polycarbonate resin composition measured in accordance with JIS K7199 using a Capilograph (Type 1C) manufactured by Toyo Seiki Seisakusho Co., Ltd. (temperature range: 60 to 400°C, barrel diameter: 9.55 mmφ) under conditions of 230°C and a shear rate of 60 s ^-1 is preferably 500 to 6000 Pa·s, more preferably 500 to 5500 Pa·s, and even more preferably 500 to 5000 Pa·s or less.

<<Method for producing substrate layer (I)>>
The method for producing the base layer (I) is not particularly limited, and any known sheet production method can be used. From the viewpoint of easy adjustment to a suitable thickness, it is preferable to use an extruder.
Examples of extruders include single-screw extruders, co-rotating intermeshing twin-screw extruders, co-rotating non-intermeshing twin-screw extruders, counter-rotating non-intermeshing twin-screw extruders, and multi-screw extruders. Among them, single-screw extruders are preferred because they have few resin retention areas, making it easy to suppress thermal deterioration of the resin during extrusion, and because the equipment costs are low. The screw used in a single-screw extruder or the like may be a screw having a general full-flight configuration with a compression ratio of about 2 to 3, or a screw equipped with a special kneading mechanism such as a barrier flight so that no unmelted material is present. In addition, an extruder having a vent mechanism may be used to remove residual volatile components in the resin or resin composition or volatile components generated by heating in the extruder.
In addition, when a methacrylic resin composition or a polycarbonate resin composition is used as the resin material constituting the base layer (I), the resin composition may be prepared in advance and then charged into an extruder and extruded, or the methacrylic resin or polycarbonate resin and additives to be blended therewith may be charged into an extruder and extruded.
As described later, the base layer (I) and the adhesive layer (II) may be produced simultaneously by coextrusion.
The film-forming temperature, melting temperature, etc. are not particularly limited and may be appropriately selected depending on the resin material constituting the base layer (I).

The surface of the substrate layer (I) is preferably smooth. The smoother the substrate layer (I), the easier it is to manufacture a laminate of the substrate layer (I) and the adhesive layer (II). In addition, when laminated glass is manufactured using such a laminate as an interlayer, the appearance quality of the laminated glass is likely to be improved. There are no particular limitations on the method for obtaining a smooth surface. For example, a smooth surface can be obtained by a method including a step of extruding a molten mixture of a resin or a resin composition from a T-die in a molten state and contacting both sides of the extruded molten mixture with a mirror-finished roll surface or a mirror-finished belt surface to form the molten mixture, and such a method is preferable. The rolls or belts used in this case are preferably made of metal or silicone rubber.

It is preferable that the substrate layer (I) has excellent penetration resistance. The penetration resistance is evaluated by measuring the penetration energy by the drop weight impact test described later. The penetration resistance of the substrate layer (I) in the drop weight impact test is preferably 5 J or more, more preferably 10 J or more, and even more preferably 13 J or more. If the penetration resistance of the substrate layer (I) is equal to or more than the lower limit, the penetration resistance of the laminated glass produced by using the laminate of the substrate layer (I) and the adhesive layer (II) as the interlayer film can be easily adjusted to a sufficient value. The penetration resistance of the substrate layer (I) can be determined by the same method as the drop weight impact test method for the interlayer film described in the examples described later. The penetration resistance can be adjusted to equal to or more than the lower limit, for example, by mixing core-shell type rubber particles with the methacrylic resin contained in the resin material constituting the substrate layer (I), selecting bisphenol A as a raw material for the polycarbonate resin contained in the resin material constituting the substrate layer (I), and/or adjusting the thickness of the substrate layer (I).

The tensile storage modulus of the base layer (I) measured by tensile dynamic viscoelasticity measurement at 25 to 50°C, a frequency of 1 Hz, and a strain of <1% is usually 800 to 5,000 MPa. The tensile storage modulus is preferably 1,000 MPa or more, more preferably 1,500 MPa or more, and preferably 3,500 MPa or less, more preferably 3,000 MPa or less, and even more preferably 2,500 MPa or less. When the tensile storage modulus is equal to or more than the lower limit, the bending rigidity of the base layer (I) is easily ensured even if the base layer (I) is thin within the moldable range, and when the tensile storage modulus is equal to or less than the upper limit, good formability into the roll shape described below is easily obtained. The tensile storage modulus can be measured by the same method as the method for measuring the tensile storage modulus of the methacrylic resin composition described above. The tensile storage modulus can be adjusted within the above range, for example, by selecting bisphenol A as a raw material for the polycarbonate resin contained in the resin material constituting the base layer (I) and/or by adjusting the thickness of the base layer (I).

It is preferable that the substrate layer (I) has a high total light transmittance. The total light transmittance of the substrate layer (I) at the thickness described below is preferably 70% or more, more preferably 80% or more, even more preferably 85% or more, and particularly preferably 89% or more. If the total light transmittance is equal to or greater than the lower limit, the transparency of the laminated glass obtained tends to be high. The total light transmittance can be measured by a haze meter using the substrate layer (I) according to the measurement method described in JIS K7361-1. The total light transmittance can be adjusted to equal to or greater than the lower limit, for example, by selecting a resin having a high total light transmittance as described above as the resin contained in the substrate layer (I), reducing the surface roughness of the substrate layer (I), and/or by selecting an additive in the resin composition constituting the substrate layer (I) or adjusting the dispersibility of the additive.

The thickness T(I) of the base layer (I) is preferably 0.90 mm or less from the viewpoint of ease of handling of the laminate of the base layer (I) and the adhesive layer (II). The thickness T(I) is preferably 0.20 mm or more, more preferably 0.25 mm or more, more preferably 0.30 mm or more, more preferably 0.35 mm or more, and even more preferably 0.40 mm or more from the viewpoint of easily obtaining the desired penetration resistance, shear relaxation modulus, and bending rigidity of the laminate described later, and is preferably 0.80 mm or less, more preferably 0.70 mm or less, and even more preferably 0.65 mm or less. The thickness T(I) can be measured with a thickness meter, and the average value measured at multiple locations (for example, 10 to 20 locations) may be used.

As long as it does not interfere with the object and effect of the present invention, the surface of the base layer (I) may be subjected to an adhesion enhancing treatment. Examples of adhesion enhancing treatments include surface treatments such as corona treatment, plasma treatment, and low-pressure ultraviolet treatment.

In addition, an easy-adhesion layer may be provided on the base layer (I) as long as it does not interfere with the object and effect of the present invention. Examples of resins contained in the easy-adhesion layer include urethane resin, polyester, polyvinyl acetate, epoxy resin, silicone, etc.

The easy-adhesion layer can be formed on the substrate layer (I) by a known method. An example of such a method includes coating the substrate layer (I) with the above-mentioned resin and drying it. The thickness of the easy-adhesion layer in a dry state is preferably 1 to 100 nm, more preferably 10 to 50 nm. The resin used for coating may be diluted with a solvent. Such a solvent is not particularly limited, but alcohols can be used, for example. The dilution concentration (percentage of the mass of solids relative to the total mass of the coating liquid) is not particularly limited, but is preferably 1 to 5 mass%, more preferably 1 to 3 mass%.

If necessary, the surface of the adhesive layer may be subjected to a surface treatment such as low-pressure ultraviolet light treatment, corona treatment, or plasma treatment in order to increase the adhesive strength with the adhesive layer (II).

<<Adhesive layer (II)>>
The laminate is composed of a substrate layer (I) and two adhesive layers (II) on both sides of the substrate layer (I). The material constituting the two adhesive layers (II) contains an adhesive resin and is the same as The materials constituting the two adhesive layers (II) are preferably the same.

The adhesive resin constituting the adhesive layer (II) is not particularly limited, but a resin having adhesiveness and a high shear relaxation modulus at high temperatures is preferred. Specific examples of adhesive resins include polyvinyl acetal resin, urethane resin, melamine resin, acrylic resin, epoxy resin, styrene-based thermoplastic elastomer, ethylene-vinyl acetate copolymer, polymethacrylic acid, poly(meth)acrylic acid ester, and ethylene-(meth)acrylic acid ester copolymer. Among these, polyvinyl acetal resin, melamine resin, acrylic resin, epoxy resin, ethylene-vinyl acetate copolymer, polymethacrylic acid, poly(meth)acrylic acid ester, and ethylene-(meth)acrylic acid ester copolymer are preferred from the viewpoint of easily suppressing the deterioration of the long-term stability of the laminated glass caused by hydrolysis due to ultraviolet light or high temperature. In addition, polyvinyl acetal resin, acrylic resin, polymethacrylic acid, poly(meth)acrylic acid ester, and ethylene-(meth)acrylic acid ester copolymer are more preferred because materials that do not have thermosetting properties are less likely to impair the workability during the production of laminated glass. In addition, polyvinyl acetal resin is particularly preferred from the viewpoint of easily producing laminated glass having excellent transparency and penetration resistance. Therefore, in a preferred embodiment of the present invention, at least one adhesive layer (II), preferably both adhesive layers (II) in the laminate contain polyvinyl acetal resin as an adhesive resin.

(Ethylene-vinyl acetate copolymer)
In the present invention, the ethylene-vinyl acetate copolymer (hereinafter, abbreviated as "EVA") is not particularly limited. The content of vinyl acetate in EVA is preferably 23 to 38% by mass, more preferably 25 to 30% by mass, and even more preferably 26 to 28% by mass, based on the mass of EVA. The lower the content of vinyl acetate units in EVA, the harder the resulting adhesive layer tends to be. When the content of vinyl acetate units is equal to or more than the lower limit, the adhesive layer is likely to have sufficient transparency even when crosslinked and cured at high temperatures, and when the content of vinyl acetate units is equal to or less than the upper limit, the adhesive layer is likely to have sufficient hardness required for impact resistance or penetration resistance.
The MFR of EVA measured under conditions of 190°C and a load of 21.18 N is preferably 4 g/10 min or more. This makes it easier to remove air bubbles when producing a laminate or an interlayer film, or when attaching the interlayer film to inorganic glass. The MFR is more preferably 4.0 to 30.0 g/10 min, and even more preferably 8.0 to 18.0 g/10 min.

In the present invention, a crosslinking agent may be added to the EVA. This allows a crosslinked structure to be formed in the EVA, and the shear relaxation modulus of the adhesive layer can be further increased.

As a crosslinking agent for EVA, organic peroxides are preferably used. Any organic peroxides can be used as long as they decompose at a temperature of 100°C or higher to generate radicals. The organic peroxide is generally selected taking into consideration the film formation temperature, composition preparation conditions, curing temperature, heat resistance of the adherend, and storage stability. In particular, organic peroxides with a decomposition temperature of 70°C or higher and a half-life of 10 hours are preferred.

As the organic peroxide, from the viewpoint of the processing temperature or storage stability of the resin composition containing EVA and an organic peroxide, it is preferable to use a hydroperoxide-based compound, a dialkyl peroxide-based compound, a peroxycarbonate-based compound, or a ketone peroxide-based compound. These may be used alone or in combination of two or more.

Examples of hydroperoxide compounds include p-menthane hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, and t-hexyl hydroperoxide.

Examples of dialkyl peroxide compounds include 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 3-di-t-butylperoxide, t-butyl-α-cumyl peroxide, di-α-cumyl peroxide, 1,4-bis((t-butyldioxy)isopropyl)benzene, 1,3-bis((t-butyldioxy)isopropyl)benzene, 2,5-dimethyl-2,5-bis(t-butylperoxy)benzene, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne, α,α'-bis(t-butylperoxyisopropyl)benzene, n-butyl-4,4-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)butane, and 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane.

Examples of peroxycarbonate compounds include t-butylperoxy-2-ethylhexyl monocarbonate and t-butylperoxyisopropyl carbonate.

Examples of ketone peroxide compounds include methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, cyclohexanone peroxide, and methylcyclohexanone peroxide.

Among these, it is preferable to use a dialkyl peroxide compound, in particular 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, from the viewpoint of easily obtaining a cured film with superior adhesive strength, heat resistance, and UV resistance.

The content of the crosslinking agent in the EVA is usually 0.5 to 5.0 parts by mass, preferably 0.5 to 3.5 parts by mass, and more preferably 0.65 to 3.5 parts by mass, per 100 parts by mass of EVA. If the content of the crosslinking agent is within the above range, a strong crosslinked structure is easily obtained, and the adhesive strength to inorganic glass is easily increased.

The resin composition containing EVA and a crosslinking agent may further contain a crosslinking aid, if necessary. The crosslinking aid can increase the gel fraction of the EVA and improve the adhesion and durability of the adhesive layer (II).

The content of the crosslinking aid is generally 10 parts by mass or less, preferably 0.1 to 5 parts by mass, and more preferably 0.1 to 2.5 parts by mass, per 100 parts by mass of EVA. If the content of the crosslinking aid is within the above range, it is easier to obtain an adhesive layer (II) with even better adhesion.

The crosslinking aid may be a compound having a radically polymerizable group as a functional group, and examples thereof include trifunctional crosslinking aids such as triallyl cyanurate and triallyl isocyanurate, monofunctional crosslinking aids such as (meth)acrylic esters (e.g., NK esters, etc.), and bifunctional crosslinking aids. Among these, triallyl cyanurate and triallyl isocyanurate are preferred, and triallyl isocyanurate is more preferred.

(Polyvinyl acetal resin)
The vinyl alcohol unit content of the polyvinyl acetal resin is not particularly limited, but is preferably 10 to 50 mol%, more preferably 15 to 40 mol%, and even more preferably 18 to 33 mol%. When the vinyl alcohol unit content is equal to or more than the lower limit and equal to or less than the upper limit, industrial production is easy, and sufficient moisture resistance of the laminate and good compatibility with the plasticizer when a plasticizer is used are easily obtained. The vinyl alcohol unit content can be adjusted to within the above range by adjusting the amount of aldehyde used in the acetalization reaction.

The average degree of acetalization of the polyvinyl acetal resin is not particularly limited, but is preferably 30 to 90 mol%, more preferably 40 to 80 mol%, even more preferably 50 to 78 mol%, and particularly preferably 60 to 76 mol%. When the average degree of acetalization is equal to or greater than the lower limit and equal to or less than the upper limit, industrial production is easy, and sufficient moisture resistance of the laminate and good compatibility with the plasticizer when a plasticizer is used are easily obtained. The average degree of acetalization can be adjusted by adjusting the amount of aldehyde used in the acetalization reaction.

The vinyl acetate unit content of the polyvinyl acetal resin is not particularly limited, but is preferably 0.1 mol% or more, more preferably 0.2 mol% or more, more preferably 0.5 mol% or more, even more preferably 1 mol% or more, particularly preferably 1.5 mol% or more, and is preferably 30 mol% or less, more preferably 15 mol% or less, more preferably 10 mol% or less, even more preferably 6 mol% or less, particularly preferably 5.4 mol% or less. When the vinyl acetate unit content is the lower limit or more and the upper limit or less, it is easy to produce industrially and to obtain the desired transparency.
In addition, when a polycarbonate resin is used as the resin material constituting the base layer, from the viewpoint of easily increasing the adhesive strength between the adhesive layer and the base layer, the vinyl acetate unit content is preferably 1 mol% or more, more preferably 2 mol% or more, even more preferably 3 mol% or more, and preferably 30 mol% or less, more preferably 20 mol% or less, more preferably 10 mol% or less, even more preferably 6 mol% or less, particularly preferably 5.4 mol% or less. The vinyl acetate unit content can be adjusted by appropriately adjusting the saponification degree of the raw material polyvinyl alcohol resin.

Polyvinyl acetal resin is produced using polyvinyl alcohol resin as a raw material. Polyvinyl alcohol resin can be obtained by a conventionally known method, that is, by polymerizing a vinyl ester compound and saponifying the resulting polymer. As a method for polymerizing a vinyl ester compound, conventionally known methods such as solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization can be applied. As a polymerization initiator, an azo initiator, a peroxide initiator, a redox initiator, and the like are appropriately selected according to the polymerization method. As a saponification reaction, conventionally known alcoholysis, hydrolysis, and the like using an alkali catalyst or an acid catalyst can be applied, and among these, a saponification reaction using methanol as a solvent and sodium hydroxide catalyst is simple and most preferable.

Examples of vinyl ester compounds include conventionally known vinyl carboxylates such as vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl stearate, and vinyl benzoate, with vinyl acetate being particularly preferred.

As the polyvinyl alcohol resin, modified polyvinyl alcohol obtained by copolymerizing a vinyl ester compound with other conventionally known monomers can also be used, provided that the purpose of the present invention is not violated. The monomer is usually used in a ratio of less than 10 mol % relative to the vinyl ester compound.

The viscosity average degree of polymerization of the polyvinyl alcohol resin is not particularly limited and is appropriately selected depending on the application, but is preferably 150 to 3,000, more preferably 200 to 2,500, and even more preferably 900 to 2,000. When the viscosity average degree of polymerization of the polyvinyl alcohol resin is equal to or greater than the lower limit and equal to or less than the upper limit, a laminate produced using the obtained polyvinyl acetal resin is likely to have sufficient strength and heat resistance, and when a laminate is produced using the obtained polyvinyl acetal resin, good film-forming properties of the adhesive layer are likely to be obtained.

The polyvinyl acetal resin used in the present invention is produced by a conventional method, but can be produced, for example, by a precipitation method under the following reaction conditions. First, an aqueous solution of polyvinyl alcohol resin with a concentration of 3 to 40% by mass is kept at a temperature range of 80 to 100°C, and then the temperature is gradually cooled over 10 to 60 minutes. When the temperature of the aqueous solution drops to -10 to 30°C, an aldehyde and an acid catalyst are added, and the acetalization reaction is carried out for 30 to 300 minutes while keeping the temperature constant. At that time, a polyvinyl acetal resin with an average acetalization degree reaching a certain level is precipitated. Thereafter, the reaction solution is heated to a temperature of 30 to 80°C over 30 to 300 minutes, and the temperature is maintained for 10 to 500 minutes. Next, a basic compound is added to the reaction solution to neutralize the acid catalyst, and the reaction solution is washed with water and dried to obtain a polyvinyl acetal resin.

When producing polyvinyl acetal resin, the basic compound added to neutralize the acid catalyst is not particularly limited, and basic sodium salts or potassium salts such as sodium hydroxide, sodium bicarbonate, and potassium hydroxide may be used, or amines such as ammonia and triethylamine may be used. Of these, sodium hydroxide is preferred.

The acid catalyst used in the acetalization reaction is not particularly limited, and either an organic acid or an inorganic acid can be used. Examples include acetic acid, paratoluenesulfonic acid, nitric acid, sulfuric acid, and hydrochloric acid. Of these, hydrochloric acid, sulfuric acid, and nitric acid are preferably used.

The aldehyde used in the acetalization reaction is not particularly limited, but conventionally known aldehydes having 1 to 8 carbon atoms are preferred, and aldehydes having 4 to 6 carbon atoms are more preferred. From the viewpoint of obtaining excellent transparency and mechanical strength of the resulting polyvinyl acetal resin, and of easily obtaining compatibility between the resulting polyvinyl acetal resin and a plasticizer described below, it is preferable to use n-butyl aldehyde. In the present invention, polyvinyl acetal obtained by using two or more types of aldehydes in combination can also be used.

A plasticizer may be added to the polyvinyl acetal resin. As such a plasticizer, a conventionally known plasticizer can be used, examples of which include carboxylate-based plasticizers such as monovalent carboxylate-based plasticizers and polyvalent carboxylate-based plasticizers; phosphate-based plasticizers; organic phosphite-based plasticizers; polymeric plasticizers such as carboxylate polyester-based plasticizers, carbonate polyester-based plasticizers, and polyalkylene glycol-based plasticizers; and ester compounds of hydroxycarboxylic acids such as castor oil and polyhydric alcohols. The plasticizers can be used alone or in combination of two or more.

Examples of monocarboxylic acid ester plasticizers include compounds obtained by condensation reactions between monocarboxylic acids such as butanoic acid, isobutanoic acid, pentanoic acid, hexanoic acid, 2-ethylhexanoic acid, heptanoic acid, octylic acid, 2-ethylhexanoic acid, and lauric acid and polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, and glycerin. Specific examples of the compounds include triethylene glycol di-2-ethylhexanoate, triethylene glycol diisobutanoate, triethylene glycol di-2-hexanoate, triethylene glycol di-2-ethylbutyrate, triethylene glycol dilaurate, ethylene glycol di-2-ethylhexanoate, diethylene glycol di-2-ethylhexanoate, tetraethylene glycol di-2-ethylhexanoate, tetraethylene glycol diheptanoate, PEG#400 di-2-ethylhexanoate, triethylene glycol mono-2-ethylhexanoate, and glycerin tri-2-ethylhexanoate. Here, PEG#400 refers to polyethylene glycol with an average molecular weight of 350 or more and 450 or less.

Examples of polycarboxylic acid ester plasticizers include compounds obtained by condensation reaction of polycarboxylic acids such as adipic acid, succinic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, and trimellitic acid with alcohols having 1 to 12 carbon atoms such as methanol, ethanol, butanol, hexanol, 2-ethylbutanol, heptanol, octanol, 2-ethylhexanol, decanol, dodecanol, butoxyethanol, butoxyethoxyethanol, benzyl alcohol, and 3-methyl-1,5-pentanediol. Specific examples of compounds include dihexyl adipate, diheptyl adipate, dioctyl adipate, di(2-ethylhexyl) adipate, di(butoxyethyl) adipate, di(butoxyethoxyethyl) adipate, mono(2-ethylhexyl) adipate, 3-methyl-1,5-pentanediol adipate, dibutyl phthalate, dihexyl phthalate, di(2-ethylbutyl) phthalate, dioctyl phthalate, di(2-ethylhexyl) phthalate, benzyl butyl phthalate, and didodecyl phthalate.

Examples of phosphate ester plasticizers or organic phosphite ester plasticizers include compounds obtained by condensation reaction of phosphoric acid or phosphorous acid with alcohols having 1 to 12 carbon atoms, such as methanol, ethanol, butanol, hexanol, 2-ethylbutanol, heptanol, octanol, 2-ethylhexanol, decanol, dodecanol, butoxyethanol, butoxyethoxyethanol, and benzyl alcohol. Specific examples of compounds include trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tri(2-ethylhexyl) phosphate, tri(butoxyethyl) phosphate, and tri(2-ethylhexyl) phosphite.

Examples of carboxylic acid polyester plasticizers include polycarboxylic acids such as oxalic acid, malonic acid, succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid, as well as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,2-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 3-methyl-2,4-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 1,6-hexanediol, 1,5-pentanediol, 1,6-pentane ...6-pentanediol, 1,5-pentanediol, 1,6-pentanediol, 1,6-pentanediol, 1,6-pentanediol, 1,6-pentanediol, 1,6-pentanediol, 1, and polyhydric alcohols such as 1,2-heptanediol, 1,7-heptanediol, 1,2-octanediol, 1,8-octanediol, 1,2-nonanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,2-decanediol, 1,10-decanediol, 1,2-dodecanediol, 1,12-dodecanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,2-bis(hydroxymethyl)cyclohexane, 1,3-bis(hydroxymethyl)cyclohexane, and 1,4-bis(hydroxymethyl)cyclohexane; and carboxylic acid polyesters obtained by ring-opening polymerization of lactone compounds such as ε-caprolactone. The terminal structure of these carboxylic acid polyesters may be, for example, a hydroxyl group or a carboxyl group, or the terminal hydroxyl group or the terminal carboxyl group may be reacted with a monovalent carboxylic acid or a monovalent alcohol to form an ester bond.

Examples of carbonate polyester plasticizers include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,2-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 3-methyl-2,4-pentanediol, 1,2-heptanediol, 1,7-heptanediol, 1,2-octanediol, and 1,8-octanediol. Examples of carbonate polyesters include those obtained by alternating copolymerization of polyhydric alcohols such as 1,2-cyclohexanediol, 1,2-nonanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,2-decanediol, 1,10-decanediol, 1,2-dodecanediol, 1,12-dodecanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,2-bis(hydroxymethyl)cyclohexane, 1,3-bis(hydroxymethyl)cyclohexane, and 1,4-bis(hydroxymethyl)cyclohexane with carbonate esters such as dimethyl carbonate and diethyl carbonate by transesterification. The terminal structure of these carbonate polyester compounds may be a carbonate ester group or a hydroxyl group, etc.

Examples of polyalkylene glycol plasticizers include polymers obtained by ring-opening polymerization of alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide with monohydric alcohols, polyhydric alcohols, monocarboxylic acids, and polycarboxylic acids as initiators.

Among these, triethylene glycol di-2-ethylhexanoate, triethylene glycol di-2-ethylbutyrate, tetraethylene glycol di-2-ethylhexanoate, tetraethylene glycol diheptanoate, dihexyl adipate, dioctyl adipate, di(2-ethylhexyl) adipate, and 3-methyl-1,5-pentanediol adipate are particularly preferred. When a polycarbonate resin is used as the resin material constituting the base layer (I), it is more preferred to use a polyvalent carboxylic acid ester plasticizer such as dihexyl adipate, dioctyl adipate, di(2-ethylhexyl) adipate, and 3-methyl-1,5-pentanediol adipate. When the above plasticizer is used, the plasticizer is not distributed between the base layer (I) and the adhesive layer (II), making it easier to obtain an excellent shear relaxation modulus of the base layer.

When a plasticizer is added to the polyvinyl acetal resin, the amount added is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, even more preferably 5 parts by mass or more, and preferably 60 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 40 parts by mass or less, and particularly preferably 30 parts by mass or less, per 100 parts by mass of the polyvinyl acetal resin. When the content of the plasticizer is equal to or more than the lower limit and equal to or less than the upper limit, it is easy to obtain a sufficient plasticizing effect and the desired mechanical strength of the laminate.

Each of the resin materials constituting the two adhesive layers (II) in the laminate may contain additives such as antioxidants, ultraviolet absorbers, adhesion regulators, silane coupling agents, and fillers (e.g., talc, silica), as long as they are not contrary to the spirit of the present invention.

When the resin material constituting the adhesive layer (II) contains an antioxidant, the type of the antioxidant is not particularly limited. For example, a conventionally known phenol-based antioxidant, a phosphorus-based antioxidant, or a sulfur-based antioxidant can be used. Among these, a phenol-based antioxidant is preferred, and an alkyl-substituted phenol-based antioxidant is particularly preferred. These antioxidants can be used alone or in combination of two or more kinds. The content of the antioxidant is not particularly limited, but is preferably 0.0001 to 5 mass %, more preferably 0.001 to 1 mass %, based on the resin composition constituting the adhesive layer (II). When the content of the antioxidant is equal to or greater than the lower limit, a sufficient effect is easily obtained. Even if the content of the antioxidant is more than 5 mass %, a significant improvement in the effect cannot be expected.

When the resin material constituting the adhesive layer (II) contains an ultraviolet absorber, the type of the ultraviolet absorber is not particularly limited. For example, conventionally known benzotriazole-based ultraviolet absorbers, oxalic acid anilide-based ultraviolet absorbers, benzoate-based ultraviolet absorbers, etc. can be used. These ultraviolet absorbers can be used alone or in combination of two or more. The content of the ultraviolet absorber is not particularly limited, but is preferably 0.0001 to 5 mass %, more preferably 0.001 to 1 mass %, based on the resin composition constituting the adhesive layer (II). If the content of the ultraviolet absorber is equal to or greater than the lower limit, a sufficient effect is easily obtained. If the content of the ultraviolet absorber is more than 5 mass %, no significant improvement in the effect can be expected.

When both the resin material constituting the substrate layer (I) and the resin material constituting the adhesive layer (II) contain an ultraviolet absorber, it is preferable that the amount of ultraviolet absorber contained in the resin material constituting the adhesive layer (II) is equal to or greater than the amount of ultraviolet absorber contained in the resin material constituting the substrate layer. If the amount of ultraviolet absorber contained in the resin material constituting the adhesive layer (II) is large, ultraviolet light irradiated from the outside is sufficiently absorbed before reaching the substrate layer, so that the amount of ultraviolet absorber added to the substrate layer can be reduced. In this case, it is easy to improve the transparency of the entire laminate.

In addition, when a polyvinyl acetal resin is used as the resin material constituting the adhesive layer and it is necessary to appropriately adjust the adhesion of the laminate to inorganic glass, the resin material may contain an adhesion regulator. As the adhesion regulator, a conventionally known one can be used. Examples thereof include sodium salts, potassium salts, magnesium salts, etc. of organic acids such as acetic acid, propionic acid, butanoic acid, hexanoic acid, 2-ethylbutanoic acid, and 2-ethylhexanoic acid, and these can be used alone or in combination of two or more kinds. The content of the adhesion regulator is preferably 0.0001 to 1 mass%, more preferably 0.0005 to 0.1 mass%, and even more preferably 0.001 to 0.03 mass% based on the mass of the polyvinyl acetal resin composition.

The method for producing the polyvinyl acetal resin composition is not limited, and known production methods can be used. Examples of such production methods include a method in which the polyvinyl acetal resin and other components added as necessary are premixed using various mixers such as a tumbler or Henschel mixer, and then melt-kneaded using a mixer such as a Banbury mixer, roll, Brabender, single-screw kneading extruder, twin-screw kneading extruder, or kneader. The melt-kneading temperature is not particularly limited, and may be appropriately selected depending on the polyvinyl acetal resin and other components added as necessary. The melt-kneading temperature is usually 160 to 240°C.

The melt viscosity of the polyvinyl acetal resin composition is not particularly limited, but when the composition is formed into a film by co-extrusion with a substrate layer, the melt viscosity is preferably large. The melt viscosity of the polyvinyl acetal resin composition measured using a Toyo Seiki Capillograph (Type 1C) (temperature range: 60 to 400°C, barrel diameter: 9.55 mmφ) under conditions of 230°C and a shear rate of 60 s ^-1 is preferably 800 to 5000 Pa·s, more preferably 1000 to 5000 Pa·s, and even more preferably 1200 to 5000 Pa·s. The melt viscosity can be adjusted within the above range, for example, by adjusting the amount of plasticizer added and/or the vinyl alcohol unit content or average acetalization degree of the polyvinyl acetal resin.

<<Method for producing adhesive layer (II)>>
The method for producing the adhesive layer (II) is not particularly limited. For example, the adhesive layer (II) can be obtained by forming the resin material constituting the adhesive layer (II) into a sheet shape using a known device such as a heat press molding machine, a calendar roll or an extruder. Alternatively, the adhesive layer (II) may be produced by dissolving or dispersing the resin material constituting the adhesive layer (II) in an organic solvent or an organic dispersion medium to obtain a coating liquid, applying the coating liquid to a release film, and then removing the organic solvent or organic dispersion medium. Alternatively, the adhesive layer (II) may be produced by applying the coating liquid to the base layer (I) and then removing the organic solvent or organic dispersion medium. Alternatively, the base layer (I) and the adhesive layer (II) may be produced simultaneously by a co-extrusion method.
The film-forming temperature, melting temperature, etc. are not particularly limited and may be appropriately selected depending on the resin material constituting the adhesive layer (II).
From the viewpoint of degassing, the surface of the adhesive layer (II) may be formed with a concave-convex structure such as melt fracture or embossing by a conventionally known method, and it is preferable to form such a structure. The shape of such a concave-convex structure is not particularly limited, and may be a conventionally known structure.

The tensile storage modulus of the adhesive layer (II) measured by tensile dynamic viscoelasticity measurement at 25°C, a frequency of 1 Hz, and a strain of <1% is preferably 0.1 to 1500 MPa, more preferably 1 to 1450 MPa, and even more preferably 10 to 1400 MPa. If the tensile storage modulus is equal to or greater than the lower limit, the laminate of the base layer (I) and the adhesive layer (II) can be easily wound up without breaking, even if the adhesive layer (II) is thin. If the tensile storage modulus is equal to or less than the upper limit, cracking of the adhesive layer due to stress generated during the production of the laminated glass can be easily prevented, and laminated glass with excellent appearance can be easily obtained.

The tensile storage modulus of the adhesive layer (II) measured by tensile dynamic viscoelasticity measurement at 50°C, a frequency of 1 Hz, and a strain of <1% is preferably 0.1 to 1450 MPa, more preferably 0.5 to 1400 MPa, and even more preferably 1 to 1300 MPa. When the tensile storage modulus is equal to or greater than the lower limit, a more preferable shear relaxation modulus of the laminate laminated with the base layer is easily obtained. When the tensile storage modulus is equal to or less than the upper limit, cracking of the adhesive layer due to stress generated during the production of the laminated glass is easily prevented, and laminated glass with excellent appearance is easily obtained.

The tensile storage modulus of the adhesive layer (II) at 25°C or 50°C can be adjusted within the above range, for example, by adjusting the amount of plasticizer added in the adhesive layer (II), adjusting the vinyl alcohol unit content of the polyvinyl acetal resin, adding a filler, and/or increasing the ratio of components with high glass transition temperatures in the adhesive resin. In addition, these tensile storage moduli can be measured by the same method as the method for measuring the tensile storage modulus of the methacrylic resin composition described above.

The thickness T(II) of one adhesive layer (II) is preferably 0.30 mm or less from the viewpoint of obtaining good rigidity against compressive shear and good adhesion to inorganic glass, and from the viewpoint of economy. It is also preferably 0.005 mm or more, more preferably 0.007 mm or more, more preferably 0.010 mm or more, more preferably 0.020 mm or more, more preferably 0.030 mm or more, even more preferably 0.040 mm or more, particularly preferably 0.050 mm or more, and is preferably 0.280 mm or less, more preferably 0.250 mm or less, and more preferably 0.200 mm or less. The thickness T(II) can be measured with a thickness meter, and the average value measured at multiple locations (for example, 10 to 20 locations) may be used.

The sum of the thicknesses of the two adhesive layers (II) arranged on both sides of the base layer (I) is defined as 2T(II). The thicknesses T(II) of the two adhesive layers (II) may be the same or different from each other, but are preferably the same. When the thicknesses T(II) of the two adhesive layers (II) are the same, 2T(II) is equal to twice T(II).

The ratio T(I)/2T(II) of the thickness T(I) of the base layer (I) to the thickness 2T(II) of the two adhesive layers (II) may be changed depending on the resin material constituting the base layer (I), the resin material constituting the adhesive layer (II), and the intended use. From the viewpoint of the adhesion and penetration resistance of each layer when laminated glass is formed, and from the viewpoint of easily obtaining the bending rigidity of the desired laminate, T(I)/2T(II) is preferably 0.5 or more, more preferably 1.0 or more, more preferably 2.0 or more, and even more preferably 3.0 or more, and is preferably 35 or less, more preferably 20 or less, and even more preferably 15 or less.

[Method of manufacturing interlayer film]
The method for producing the intermediate film is not particularly limited as long as it is a method capable of producing a laminate having adhesive layers (II) on both sides of a base layer (I), i.e., a method capable of producing a laminate laminated in the order of adhesive layer (II)/base layer (I)/adhesive layer (II) and, when the intermediate film contains a plurality of laminates, a method capable of bonding the plurality of laminates, or, when the intermediate film contains a plurality of laminates, a method capable of producing an intermediate film laminated in the order of, for example, adhesive layer (II)/base layer (I)/adhesive layer (II)/adhesive layer (II)/base layer (I)/adhesive layer (II), etc.
Examples of the method for producing the laminate include a method of laminating the base material layer (I) and the adhesive layer (II) by a known method such as a thermal lamination method or a pressure bonding method, a method of dissolving or dispersing the material constituting the adhesive layer (II) in an organic solvent or an organic dispersion medium to obtain a coating liquid, applying this coating liquid to one side of the base material layer (I), removing the organic solvent or the organic dispersion medium, and further applying the coating liquid to the other side of the base material layer (I), and removing the organic solvent or the organic dispersion medium, and a method of co-extruding the material constituting the base material layer (I) and the material constituting the adhesive layer (II).The co-extrusion method is preferred from the viewpoints of production cost, the environmental burden caused by the organic solvent or the organic dispersion medium, and the uniformity of the film thickness.
When the intermediate film includes a plurality of laminates, examples of a method for bonding the plurality of laminates include a method in which the plurality of laminates are laminated by a known method such as a thermal lamination method or a pressure bonding method.
Furthermore, when the intermediate film includes a plurality of laminates, an example of a method for laminating the plurality of layers in the order of, for example, adhesive layer (II)/base layer (I)/adhesive layer (II)/adhesive layer (II)/base layer (I)/adhesive layer (II) can be a method of laminating the plurality of layers by a known method such as a thermal lamination method or a pressure bonding method.
When the intermediate film has any structure (e.g., a conductive structure, a sound-insulating structure, a design layer, or a combination thereof), for example, the structure may be imparted in advance to the base material layer (I) and/or the adhesive layer (II) by a thermal lamination method, a pressure bonding method, a printing method, or the like, the structure may be imparted simultaneously with lamination of the base material layer (I) and the adhesive layer (II), the structure may be imparted simultaneously with lamination of a plurality of laminates, or the structure may be formed on a release film and laminated with the base material layer (I) and/or the adhesive layer (II) and then the release film may be peeled off to transfer the structure to the base material layer (I) and/or the adhesive layer (II).

When a laminate or intermediate film is manufactured by a co-extrusion method, the resin materials constituting the base layer (I) and adhesive layer (II) are each heated and melted, and are co-extruded in a molten state from a T-die having a wide discharge opening in a state in which the adhesive layer (II) is laminated on both surfaces of the base layer (I) or in the order of adhesive layer (II)/base layer (I)/adhesive layer (II)/adhesive layer (II)/base layer (I)/adhesive layer (II), etc.

It is preferable that each molten resin material constituting the base layer (I) and the adhesive layer (II) is melt-filtered through a filter before lamination. By performing multi-layer molding using each melt-filtered molten resin material, it becomes easier to obtain an extruded resin sheet with fewer defects caused by foreign matter and gels. The filter material of the filter is appropriately selected depending on the use temperature, viscosity, filtration accuracy, etc. Examples include nonwoven fabric made of glass fiber, etc.; sheet-like material made of cellulose impregnated with phenolic resin; sintered sheet-like material of nonwoven metal fiber fabric; sintered sheet-like material of metal powder; wire mesh; and combinations thereof. Among them, from the viewpoint of heat resistance and durability, a filter made of multiple laminated sheets of sintered nonwoven metal fiber fabric is preferable. The filtration accuracy of the filter is not particularly limited, and is preferably 30 μm or less, more preferably 15 μm or less, and particularly preferably 5 μm or less.

Lamination methods include the feed block method, in which lamination is performed before flowing into the T-die, and the multi-manifold method, in which lamination is performed inside the T-die. The multi-manifold method is preferred from the viewpoint of improving the interfacial smoothness between layers of the extruded resin sheet.

The molten laminate coextruded from the T-die is cooled using multiple cooling rolls. In one embodiment of the present invention, three or more adjacent cooling rolls are used, and the molten laminate resin sheet is sandwiched between the nth (n≧1) cooling roll and the n+1th cooling roll, and the operation of wrapping the sheet around the n+1th cooling roll is repeated multiple times from n=1 to cool the sheet. For example, when three cooling rolls are used as shown in FIG. 1, the number of repetitions is two.

Examples of cooling rolls include metal rolls and elastic rolls with a thin metal film on the outer periphery (hereinafter also referred to as metal elastic rolls). Examples of metal rolls include drilled rolls and spiral rolls. The surface of the metal roll may be a mirror surface, or may have a pattern or unevenness. The metal elastic roll is, for example, made of a shaft roll made of stainless steel or the like, a thin metal film made of stainless steel or the like covering the outer periphery of the shaft roll, and a fluid sealed between the shaft roll and the thin metal film, and can exhibit elasticity due to the presence of the fluid. The thickness of the thin metal film is preferably about 2 to 5 mm. The thin metal film is preferably flexible and has a seamless structure without welded joints. Such a thin metal elastic roll with a thin metal film is durable, and if the thin metal film is made mirror-finished, it can be handled in the same way as a normal mirror roll, and if a pattern or unevenness is given to the thin metal film, it becomes a roll to which the shape can be transferred, so it is easy to use.

After cooling, the resulting laminate is taken up by a take-up roll. The above-mentioned co-extrusion, cooling, and take-up steps are carried out continuously.

1 shows, as one embodiment, a schematic diagram of a production apparatus including a T-die 11, first to third cooling rolls 12 to 14, and a pair of take-up rolls 15. The molten laminated resin sheet coextruded from the T-die 11 is cooled by the first to third cooling rolls 12 to 14 and taken up by the pair of take-up rolls 15.
The configuration of the manufacturing apparatus can be appropriately modified in design without departing from the spirit of the present invention. For example, a fourth or subsequent cooling roll may be provided adjacent to the rear of the third cooling roll 14. Furthermore, a transport roll may be provided between a plurality of adjacent cooling rolls and a take-up roll as necessary.

When the base layer (I) and the adhesive layer (II) are formed by a co-extrusion method, preferably, in the laminate, the melt viscosity (η ₁ ) of the resin material constituting the base layer (I) is 1 ^× 10 ² Pa·s or more and 1×10 4 Pa·s or less, and the melt viscosities (η 2 ) and (η ₃ ) of the resin materials constituting each adhesive layer (II) are 1×10 ² Pa·s or more and 1×10 ⁴ Pa·s or less, respectively, as measured at a temperature of ₂₃₀ ° C. and a shear rate of ⁶⁰ s-1 in accordance with JIS K 7199, and the melt viscosity ratios (η ₁ /η ₂ ) and (η ₁ /η ₃ ) are 1.0 or more and 4.0 or less. _η1 is more preferably 5.0× ¹⁰² Pa·s or more, more preferably 1.0× ¹⁰³ Pa·s or more, more preferably 6.0× ¹⁰³ Pa·s or less, more preferably 5.0× ¹⁰³ Pa·s or less. _η2 and _η3 are more preferably 5.0× ¹⁰² Pa·s or more, more preferably 1.0× ¹⁰³ Pa·s or more, more preferably 2.0× ¹⁰³ Pa·s or more, more preferably 6.0× ¹⁰³ Pa·s or less, more preferably 5.0× ¹⁰³ Pa·s or less. _η1 / _η2 and _η1 / _η3 are more preferably 3.0 or less, more preferably 2.0 or less. When the melt viscosity ratio is equal to or more than the lower limit and equal to or less than the upper limit, the thickness of the adhesive layer (II) can be adjusted more easily, and even when the adhesive layer (II) is made thin, the thickness ratio is likely to be uniform, and the quality of the laminated glass is likely to be more stable.

The interlayer preferably has a penetration resistance. The penetration resistance of the interlayer is determined by a drop weight impact test in accordance with ASTM D3763, similar to the penetration resistance of the base layer (I). The penetration resistance of the interlayer measured under conditions of a measurement temperature of 23°C, a load of 2 kg, and an impact speed of 9 m·s ⁻¹ is preferably 12 J or more, more preferably 13 J or more, even more preferably 14 J or more, and particularly preferably 15 J or more. The upper limit is not particularly limited, but is usually 25 J or less. In the above test, when it exceeds 30 J, there are many cases where the interlayer does not penetrate, but the measured value may not be accurate. If the penetration resistance of the interlayer is equal to or greater than the lower limit, the interlayer is less likely to break even if a flying object collides with the laminated glass and breaks it, thereby improving safety. The penetration resistance can be adjusted to equal to or greater than the lower limit by, for example, adjusting the thickness of the base layer (I) and the adhesive layer (II), adjusting the thickness ratio thereof, and/or improving the shear storage modulus of the base layer (I), the adhesive layer (II), the laminate, and the interlayer.

The interlayer film of the present invention can provide laminated glass with excellent bending strength. The bending strength of the laminated glass can be evaluated by performing a four-point bending test of the laminated glass in accordance with ISO1288-4:2016 and determining the amount of deflection at the center of the laminated glass where the amount of deformation is the largest, as described in the Examples below. The smaller the amount of deflection, the better the bending strength of the laminated glass. The amount of deflection is preferably 3.0 mm or less, more preferably 2.8 mm or more, more preferably 2.7 mm or less, more preferably 2.5 mm or less, more preferably 2.3 mm or less, more preferably 2.2 mm or less, more preferably 1.8 mm or less, more preferably 1.7 mm or less, more preferably 1.5 mm or less, even more preferably 1.0 mm or less, and particularly preferably 0.8 mm or less. The lower limit of the amount of deflection is 0 mm.

In cases where it is difficult to actually measure the bending strength of the laminated glass after a long time has elapsed, the thickness of a single sheet of glass having a bending strength equivalent to the bending strength of the laminated glass at a time when only a short time (for example, 30 minutes or less) has elapsed since the laminated glass was applied with a load is calculated, and the bending strength of the laminated glass after a long time can be evaluated using a theoretical formula for four-point bending deformation of such a sheet of glass. This thickness of the sheet of glass is called effective glass thickness. Although several formulas for calculating the effective glass thickness have been reported, the present invention uses the effective glass thickness (h _ef;w ) for calculating the deflection obtained by the method described in Non-Patent Document 1. The effective glass thickness equivalent to 24 hours at 50°C, calculated by the method described in the examples below, is preferably 4.2 mm or more, more preferably 4.5 mm or more, more preferably 4.7 mm or more, more preferably 5.0 mm or more, more preferably 5.2 mm or more, more preferably 5.5 mm or more, more preferably 6.0 mm or more, even more preferably 6.4 mm or more, and particularly preferably 6.5 mm or more. Furthermore, the effective glass thickness equivalent to that after 10 years at 50°C, as determined by the method described in the Examples below, is preferably 4.0 mm or more, more preferably 4.1 mm or more, more preferably 4.2 mm or more, more preferably 4.4 mm or more, more preferably 4.5 mm or more, more preferably 4.9 mm or more, even more preferably 5.0 mm or more, and particularly preferably 5.2 mm or more. The upper limit of these effective glass thicknesses is not defined because it depends on the thickness of the interlayer film, and the lower limit is 3.8 mm.

The interlayer film of the present invention can provide a laminated glass having excellent transparency. Therefore, even when the type of inorganic glass of the outer layer is changed depending on the application, the laminated glass of the present invention can maintain excellent transparency.
From the viewpoint of easily imparting superior transparency to the laminated glass, the haze of one laminate contained in the interlayer film is preferably 5% or less, more preferably 2% or less, and even more preferably 1% or less. The lower limit of the haze is not particularly specified. The haze of one laminate is usually 0.01% or more. In one embodiment of the present invention, the haze is 0% or more and 2% or less.
The haze can be adjusted to the upper limit or less by selecting the resin contained in the adhesive layer (II), selecting the type of plasticizer contained in the adhesive layer (II) or reducing the content of the plasticizer, and/or thinning the thickness of the interlayer. The haze can be measured, for example, for a laminated glass manufactured using an interlayer having a thickness of 0.8 mm or less (for example, 0.8 mm) using a haze meter SH7000 (manufactured by Nippon Denshoku Kogyo Co., Ltd.) in accordance with JIS K7136:2000.

The interlayer of the present invention can result in laminated glass with very low tintability. The laminated glass can be as colorless as possible.
From the viewpoint of easily imparting lower colorability to the laminated glass, the yellowness index (YI) of one laminate included in the interlayer film is preferably 3 or less, more preferably 2 or less, even more preferably 1 or less, and particularly preferably 0.5 or less. The yellowness index is 0 or more. In one embodiment of the present invention, the yellowness index is 0 or more and 2 or less.
The yellowness can be adjusted to the upper limit or less by selecting the resin contained in the adhesive layer (II), reducing the vinyl acetate unit content of the polyvinyl acetal resin contained in the adhesive layer (II), and/or thinning the thickness of the interlayer. The yellowness can be measured, for example, for a laminated glass manufactured using an interlayer having a thickness of 0.8 mm or less (for example, 0.8 mm) using a haze meter SH7000 (manufactured by Nippon Denshoku Kogyo Co., Ltd.) in accordance with JIS Z8722:2009.

The laminated glass of the present invention has excellent transparency due to the interlayer film, so inorganic glass can be selected according to the application while ensuring sufficient transparency of the laminated glass. The haze of the laminated glass of the present invention is not particularly limited, and it is preferably the same haze as the haze of the interlayer film described above.

The laminated glass of the present invention can have extremely low colorability due to the interlayer, so inorganic glass can be selected according to the application while ensuring sufficient transparency of the laminated glass. The yellowness of the laminated glass of the present invention is not particularly limited, and it is preferably the same as the yellowness of the interlayer described above.

As is well known, the safety of laminated glass depends on the adhesive strength between the interlayer and the outer layer of glass. This adhesive strength is preferably high enough to ensure that glass fragments remain attached to the interlayer when the glass is mechanically broken, and glass fragments with sharp edges cannot be peeled off. However, if the adhesive strength between the interlayer and the glass is too high, a colliding object may penetrate the laminated glass. If the adhesive strength of the interlayer to the glass is moderately low, the interlayer is stretched at the collision site and partially peels off from the glass, and deforms, thereby attenuating the collision energy and suppressing the penetration of the colliding object. That is, it is preferable that the adhesive strength between the glass and the interlayer in the laminated glass is high enough to ensure that glass fragments remain attached to the interlayer when the glass is broken, and is not too high enough to prevent a decrease in penetration resistance.
From this viewpoint, the adhesion between the inorganic glass and the interlayer film evaluated by the compressive shear test is preferably 5 MPa or more and 35 MPa or less, more preferably 10 MPa or more and 30 MPa or less, and even more preferably 15 MPa or more and 25 MPa or less. The adhesion between the inorganic glass and the interlayer film can be adjusted within the above range, for example, by increasing the vinyl alcohol unit content of the polyvinyl acetal resin contained in the adhesive layer (II) and/or adding an adhesion regulator or filler to the adhesive layer (II). The adhesion between the inorganic glass and the interlayer film can be measured, for example, by the compressive shear test described in JP-A-2006-13505. That is, as shown in FIG. 3, the adhesion can be measured by setting the laminated glass in a compressive shear tester and performing a compressive shear test.

If the adhesive strength between the interlayer film and the inorganic glass and the heat resistance of the interlayer film are insufficient, the heat creep resistance of the laminated glass is likely to decrease. The interlayer film of the present invention can provide a laminated glass having excellent heat creep resistance. The heat creep resistance of the laminated glass can be evaluated by measuring the distance of the slippage caused in the laminated glass when an accelerated test is carried out for one week under conditions of a load of 37 kg/m ² and an atmospheric temperature of 100° C. Specifically, it can be evaluated by the method described in the Examples below. The heat creep resistance of the laminated glass of the present invention is preferably 1 mm or less, more preferably 0.5 mm or less. If the heat creep resistance is equal to or less than the upper limit, it is easy to prevent the problem of the laminated glass being caused to fall off or move due to thermal slippage. The heat creep resistance can be adjusted to equal to or less than the upper limit by increasing the shear storage modulus or melt viscosity of the adhesive layer (II).

[Laminated glass]
The interlayer film of the present invention is used by being sandwiched between two sheets of inorganic glass. For example, inorganic glass such as float glass, polished plate glass, figured plate glass, tempered glass, wired plate glass, or heat absorbing plate glass can be used as the inorganic glass. For applications requiring high strength, tempered glass is preferred. The inorganic glass may be either colorless or colored. The type and thickness of the two sheets of inorganic glass may be the same or different from each other.

The two pieces of inorganic glass may be made of the same material or different materials. Examples include soda-lime glass, borosilicate glass, alkali-free glass, and quartz glass, with soda-lime glass being preferred.

The tempered glass may be air-cooled tempered glass, semi-air-cooled tempered glass, or chemically strengthened glass, which has a lower compressive stress (hereinafter also referred to as surface compressive stress or CS) on the glass surface than air-cooled tempered glass (e.g., CS of 50 MPa or less). Air-cooled tempered glass sheets have a greater depth of compressive stress layer (hereinafter also referred to as DOL) than general chemically strengthened glass sheets, so that scratches caused by flying stones or the like are less likely to penetrate the compressive stress layer in laminated glass manufactured using air-cooled tempered glass sheets. Furthermore, in laminated glass manufactured using semi-air-cooled tempered glass sheets or chemically strengthened glass sheets, cracks caused by scratches caused by flying stones or the like are less likely to progress into the glass surface.

Air-cooled tempered glass is made by rapidly cooling a uniformly heated glass sheet from a temperature near its softening point, and generating compressive stress on the glass surface due to the temperature difference between the glass surface and the interior of the glass, thereby strengthening the glass surface.
As a method for producing tempered glass, a well-known method can be adopted in which glass heated to near its softening temperature is quenched at room temperature to generate residual stress in the thickness direction of the glass, thereby forming a compressive stress layer on the glass surface. The heating temperature of the glass sheet is typically a temperature equal to or higher than the strain point and equal to or lower than the softening point of the material constituting the glass sheet.

Chemically strengthened glass is glass whose surface has been strengthened by chemical treatment. Examples of chemical treatment methods include ion exchange. In the ion exchange method, glass is immersed in a treatment liquid (e.g., molten potassium nitrate) and ions with a small ionic radius (e.g., sodium ions) contained in the glass are exchanged for ions with a large ionic radius (e.g., potassium ions), thereby generating compressive stress on the glass surface. The compressive stress is generated over the entire surface of the glass, and a compressive stress layer of uniform depth is formed over the entire surface of the glass.

The size of CS on the glass surface and the DOL formed on the glass surface can be adjusted by the chemical treatment time and/or the chemical treatment temperature, respectively. For example, when the chemical treatment temperature is the same, the longer the chemical treatment time, the deeper the DOL. Also, when the chemical treatment temperature is the same, the longer the chemical treatment time, the larger the CS will be at first, but the CS will become smaller halfway through. Therefore, there is no one-to-one correspondence between DOL and CS size.

Glass surfaces often have invisible scratches, and in order to prevent glass cracks originating from scratches, a compressive stress layer deeper than the depth of the scratches is required. From this viewpoint, it is preferable that the DOL is greater than 10 μm. The DOL is preferably 20 μm or more, and more preferably 28 μm or more.

Chemically strengthened glass generally contains, in terms of mole percentages based on oxides, 56 to 75% SiO ₂ , 1 to 20% Al ₂ O ₃ , 8 to 22% Na ₂ O , 0 to 10% K ₂ O , 0 to 14% MgO , 0 to 5% ZrO ₂ , and 0 to 10% CaO. Each component will be described below, with % meaning mole %.

SiO ₂ is known as a component that forms a network structure in the glass microstructure, and is the main component that constitutes glass. The content of SiO ₂ is usually 56% or more, preferably 60% or more, more preferably 63% or more, and even more preferably 65% or more. The content of SiO ₂ is usually 75% or less, preferably 73% or less, and more preferably 71% or less. If the content of SiO ₂ is equal to or more than the lower limit, it is advantageous in terms of stability and weather resistance as glass. On the other hand, if the content of SiO ₂ is equal to or less than the upper limit, it is advantageous in terms of meltability and moldability.

Al ₂ O ₃ has the effect of improving ion exchange performance in chemical strengthening, and in particular has a large effect of improving CS. It is also known as a component that improves the weather resistance of glass. It also has the effect of suppressing the penetration of tin from the bottom surface during float forming. The content of Al ₂ O ₃ is usually 1% or more, preferably 3% or more, and more preferably 5% or more. The content of Al 2 O 3 is usually 20% or less, preferably 17% or less, more preferably 12% or less, even more preferably 10% or less, and particularly preferably 7% or less. When the content of Al ₂ O ₃ is equal to or more than the lower limit, it is easy to obtain the desired CS and to obtain _the effect of suppressing the penetration of tin. On the other hand, when the content of Al ₂ O ₃ is equal to or less than the upper limit, the devitrification temperature is unlikely to rise significantly even when the viscosity of the glass is high, so _that it is likely to be advantageous in terms of melting and forming in a soda-lime glass production line.

The total content of _SiO2 and _{Al2O3 , SiO2} + _{Al2O3 ,} is preferably 80% or less, more preferably 79% or less, particularly preferably 78% or less, and is preferably 70% or more, more preferably 72% or more. When the total is equal to or less than the upper limit, it is easy to prevent the viscosity of the glass from increasing at high temperatures, making it difficult to melt. When the total is equal to or more than the lower limit, it is easy to show good crack resistance even when indented.

Na ₂ O is an essential component for forming compressive stress by ion exchange, and has the effect of deepening the DOL. It is also a component for lowering the high-temperature viscosity and devitrification temperature of glass, and improving the meltability and moldability of glass. The content of Na ₂ O is usually 8% or more, preferably 12% or more, more preferably 13% or more. The content of Na ₂ O is usually 22% or less, preferably 20% or less, more preferably 16% or less. When the content of Na ₂ O is equal to or more than the lower limit, it is easy to form a desired compressive stress, and when the content of Na ₂ O is equal to or less than the upper limit, it is easy to obtain sufficient weather resistance.

K ₂ O is not essential, but may be contained since it has the effect of increasing the ion exchange rate and deepening the DOL. On the other hand, if the amount of K ₂ O is too large, sufficient CS cannot be obtained. When K ₂ O is contained, its content is preferably 10% or less, more preferably 8% or less, and particularly preferably 6% or less. When the content of _{K 2} O is equal to or less than the lower limit, sufficient CS is easily obtained.

Although MgO is not essential, it is a component that stabilizes the glass. When MgO is included, its content is preferably 2% or more, more preferably 3% or more, and particularly preferably 3.6% or more. The MgO content is usually 14% or less, preferably 8% or less, and more preferably 6% or less. When the MgO content is equal to or greater than the lower limit, the glass is more likely to have good chemical resistance. In addition, the melting property at high temperatures is more likely to be good, and devitrification is less likely to occur. On the other hand, when the MgO content is equal to or less than the upper limit, the glass is more likely to maintain its resistance to devitrification, and a sufficient ion exchange rate is more likely to be obtained.

_ZrO2 is not essential, but it is generally known to have the effect of increasing CS in chemical strengthening. However, even if a small amount of _ZrO2 is contained, the effect is not large compared to the increase in cost. Therefore, any amount of _ZrO2 may be contained within the range allowed by the cost, but if _ZrO2 is contained, its content is preferably 5% or less.

CaO is not essential, but is a component that stabilizes glass. Since CaO tends to inhibit the exchange of alkali ions, it is preferable to reduce the content or not contain CaO, especially when it is desired to increase the DOL. On the other hand, in order to improve chemical resistance, it is preferable to contain preferably 2% or more, more preferably 4% or more, and particularly preferably 6% or more. When CaO is contained, its content is preferably 10% or less, more preferably 9% or less, and particularly preferably 8.2% or less. When the CaO content is less than the upper limit, it is easy to maintain a sufficient ion exchange rate and easy to obtain the desired DOL.

Chemically strengthened glass may optionally contain SrO. SrO can reduce the high-temperature viscosity of glass and the devitrification temperature. On the other hand, since SrO has the effect of reducing ion exchange efficiency, it is preferable not to contain SrO, especially when it is desired to increase the DOL. When SrO is contained, its content is preferably 3% or less, more preferably 2% or less, and particularly preferably 1% or less.

Chemically strengthened glass may optionally contain BaO. BaO can reduce the high-temperature viscosity of glass and the devitrification temperature. On the other hand, BaO has the effect of increasing the specific gravity of glass, so it is preferable not to contain BaO when weight reduction is the objective. When BaO is contained, its content is preferably 3% or less, more preferably 2% or less, and particularly preferably 1% or less.

_TiO2 is present in large amounts in natural raw materials and is known to be a source of yellow coloring. Therefore, from the viewpoint of avoiding an increase in the yellowness of glass, the content of _TiO2 is preferably 0.3% or less, more preferably 0.2% or less, and particularly preferably 0.1% or less.

Chemically strengthened glass may contain components other than those mentioned above. The total content of such components is preferably 5% or less, more preferably 3% or less, and particularly preferably 1% or less.

The thickness of the inorganic glass is not particularly limited, and is, for example, 0.5 to 20 mm. If the thickness of the inorganic glass is 6 mm or less, the transparency of the laminated glass tends to be higher, and the laminated glass becomes lighter.

The inorganic glass may not only be flat, but may also be shaped to have at least a bent or curved portion. For example, glass shaped to have a bent or curved portion may be used for the image display surfaces of devices such as televisions, personal computers, smartphones, and car navigation systems, and laminated glass manufactured using the interlayer film of the present invention may be used as such glass.

The inorganic glass may be provided with structures such as conductive structures, sound insulation structures, decorative or design layers, and combinations thereof, all or part of the inorganic glass, as long as they do not interfere with the objectives and effects of the present invention.

The laminated glass of the present invention may be used alone or in a combination of two or more sheets. When used in a combination of two or more sheets, the laminated glass has a structure of, for example, inorganic glass/adhesive layer (II)/substrate layer (I)/adhesive layer (II)/inorganic glass/adhesive layer (II)/substrate layer (I)/adhesive layer (II)/inorganic glass. When used in a combination of two or more sheets, the materials and thicknesses constituting the laminated glass may be the same as or different from each other.

A spacer may be used in the laminated glass of the present invention. The use of a spacer can prevent moisture and the like from penetrating into the interlayer. The spacer is made of, for example, a metal or alloy such as aluminum or stainless steel, or a resin. Examples of spacers include known frame-shaped spacers or hollow pipe materials used in double-glazing or dimming elements, etc.

[Method of manufacturing laminated glass]
The laminated glass of the present invention can be produced by a conventionally known method. Examples of such methods include a method using a vacuum laminator, a method using a vacuum bag, a method using a vacuum ring, and a method using a nip roll. In addition, a method in which the glass is temporarily pressed by the above method and then put into an autoclave for main bonding can also be mentioned.

When a vacuum laminator is used, inorganic glass, an interlayer film and inorganic glass are laminated at a reduced pressure of, for example, 1×10 ⁻⁶ to 3×10 ⁻² MPa at 60 to 200° C., particularly 80 to 160° C., to produce laminated glass.

When a vacuum bag or vacuum ring is used, as described in, for example, EP 1235683, inorganic glass, an interlayer film and inorganic glass are laminated at 100 to 160° C. under a pressure of about 2×10 ⁻² MPa to produce laminated glass.

When using nip rolls, the inorganic glass, interlayer film, and inorganic glass are stacked together and degassed with the rolls at a temperature below the flow start temperature of the interlayer film, and then heated to a temperature close to the flow start temperature of the interlayer film to press the inorganic glass, interlayer film, and inorganic glass together to produce laminated glass. More specifically, for example, the inorganic glass, interlayer film, and inorganic glass are stacked together and heated to 30 to 70°C with an infrared heater or the like, degassed with the rolls, and then heated to 50 to 150°C, after which the inorganic glass, interlayer film, and inorganic glass are pressed together with the rolls to produce laminated glass.

When the laminated glass is temporarily bonded by the above method and then placed in an autoclave for full bonding, the operating conditions for the autoclave process may be appropriately selected depending on the thickness or configuration of the laminated glass. The autoclave process can be carried out, for example, at a pressure of 0.5 to 1.5 MPa and at 100 to 160°C for 0.5 to 3 hours.

When the interlayer film to be laminated with inorganic glass contains multiple laminates, as described above in the paragraph [Method of manufacturing interlayer film], the multiple laminates are laminated by a known method to produce an interlayer film, and then the interlayer film is joined to inorganic glass by the method described above to produce laminated glass. However, laminated glass can also be produced by stacking the multiple laminates between two sheets of inorganic glass and joining them by the method described above.

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. Note that the physical properties in the examples and comparative examples were measured or evaluated by the following methods.

[Bending stiffness]
From each laminate used in the examples and comparative examples described later, a sheet having a length of 40 mm and a width of 30 mm was prepared. From each prepared sheet, three test pieces of 40 mm x 10 mm were cut out with reference to JIS-7017. A three-point bending test was performed on each obtained test piece using an autograph (manufactured by Shimadzu Corporation), and the bending modulus at 25 ° C. was measured when the distance between the supports was 16 mm. For each laminate, the average value of the bending modulus obtained by the measurement was adopted as the bending modulus of the laminate. Using the bending modulus and thickness, the bending stiffness at 25 ° C. of each laminate was calculated according to the following formula (2). 0.38 was used as the Poisson's ratio.

[Shear relaxation modulus G(t=f ^-1 )]
Test pieces with a diameter of 8 mm were cut out from the interlayer films produced in the Examples and Comparative Examples described below. By performing shear dynamic viscoelasticity measurements under the following conditions: measurement temperature -50 to 250°C, strain < 1%, temperature rise measurement, temperature rise rate 3°C/min, and measurement in a nitrogen atmosphere, Master curves for the shear storage modulus G'(f) and the shear loss modulus G''(f) were obtained. Using the time-temperature conversion rule, the shear relaxation modulus equivalent to the shear relaxation modulus after 24 hours at f=1.2×10 ⁻⁵ Hz (50° C.) is calculated from the obtained master curve. (frequency) and f = 3.2 × 10 ^-9 Hz (frequency for determining the shear relaxation modulus equivalent to the shear relaxation modulus after 10 years at 50 ° C. ₎ G 2 (t=f ⁻¹ ) and G ₂ (t=f ⁻¹ ) were each calculated by the following formula (1).
G(t=f ^-1 )=G'(f)－0.4G''(0.5f) (1)
In formula (1), f is a frequency of 1.2×10 ⁻⁵ Hz (when determining G ₁ (t=f ⁻¹ )) or a frequency of 3.2×10 ⁻⁹ Hz (when determining G ₂ (t= f ⁻¹ ) is obtained. G′(f) is the shear storage modulus (MPa) at 50° C. and each frequency, and G″(0.5f) is the shear storage modulus (MPa) at 50° C. and each frequency. Shear loss modulus (MPa).

[Shear relaxation modulus G(t)]
The thickness of each layer of the interlayer used in Example 13 described later was measured with a thickness meter. The shear relaxation modulus of each layer was also measured in the same manner as in the shear dynamic viscoelasticity measurement described above. The overall thickness of the interlayer film produced in Example 13 was measured with a thickness meter, and the thickness ratio of each layer in the interlayer film (the ratio of the thickness of each layer in the interlayer film) was calculated.
Using the thickness ratio and shear relaxation modulus of each layer thus determined, the shear relaxation modulus G ₁ (t) and G ₂ (t) of the interlayer were determined according to the following formula (3).
In formula (3), the shear relaxation modulus of each layer is 50° C., a frequency of 1.2×10 ⁻⁵ Hz (when calculating G ₁ (t)) or 50° C., a frequency of 3.2×10 ⁻⁹ Hz is the shear relaxation modulus at frequency (for determining G ₂ (t)), and M is unity.

[Shear transfer coefficient]
The thickness of each layer of the interlayer film and the entire interlayer film used in the examples and comparative examples described below were measured with a thickness meter.
A four-point bending test was carried out on each of the laminated glasses produced in the Examples and Comparative Examples described below. The distance between the supporting points was set to 0.3 m.
The shear transfer coefficient Γ ₁ at 50° C. and 1.2×10 ⁻⁵ Hz and the shear transfer coefficient Γ ₂ at 50° C. and 3.2×10 ⁻⁹ Hz of each interlayer film were calculated using the following formula (4).
In the above formula, _hs = 0.5 × ( _h1 + _h2 ) + _{hv , Is} = _hs2 × ^h1 × _{h2 ÷} ( _h1 + _h2 ), _h1 and _h2 are the thicknesses of the two float glasses (unit: mm), _hv is the thickness of the interlayer (unit: mm), E is the Young's modulus of the float glass (unit: MPa), G(t=f ^-1 ) is _G1 (t=f-1) (when determining the shear transfer coefficient Γ1 ₎ or _G2 (t=f ^{-1 )} (when determining the shear transfer coefficient _Γ2 ) determined by the method described above, and a is the distance between the supports in the four-point bending test (unit: m).

[Dropping weight impact test]
The drop weight impact test of the interlayer film was carried out in accordance with ASTM D3763. Specifically, a test piece measuring 60 mm in length and 60 mm in width was cut out from each interlayer film produced in the Examples and Comparative Examples described below, and a drop weight impact test was carried out using a drop weight impact tester (CEAST9350 manufactured by Instron) under conditions of a measurement temperature of 23°C, a load of 2 kg, and an impact speed of 9 m·s ^-1 . The penetration energy was calculated from the area of the SS curve from the moment when the tip of the striker contacted the test piece (when the test force was sensed) to the moment when the test piece was penetrated (when the test force returned to zero), and this was taken as the penetration resistance of the interlayer film.

[Melt Viscosity]
The melt viscosity (η ₁ ) of each resin material constituting each base layer (I) and the melt viscosity (η ₂ ) and (η ₃ ) of each resin material constituting each adhesive layer (II) used in the examples and comparative examples described below were measured at a temperature of 230° C. and a shear rate of 60 s ^-1 in accordance with JIS K 7199.

[Four-point bending test of laminated glass]
Using each of the laminated glasses with a width of 305 mm and a length of 610 mm produced in the Examples and Comparative Examples described below, a four-point bending test was carried out in accordance with ISO1288-4:2016 under the conditions of a load span of 150 mm, a support span of 300 mm, a load of 1 kN, a load speed of 0.1 mm/sec, a test temperature of 50°C, and a maximum test time of 24 hours, to measure the load-deflection behavior. The central part with the largest deformation 24 hours after the load was applied was recorded as the deflection amount.

[Effective glass thickness of laminated glass]
For each of the laminated glasses produced in the Examples and Comparative Examples described below, the effective glass thickness equivalent to that after 24 hours at 50° C. and the effective glass thickness equivalent to that after 10 years at 50° C. were calculated using the calculation method described in Non-Patent Document 1. The parameters used in the calculation, that is, the thickness and Young's modulus of the float glass and the support span, were the same as those in the previous paragraph [Four-point bending test of laminated glass].

[Evaluation of heat creep resistance of laminated glass]
Each laminate produced in the Examples and Comparative Examples described later was cut to a size of 135 mm long x 50 mm wide. Next, as shown in Fig. 4, an intermediate film 71 was sandwiched between float glasses 51 and 52 measuring 165 mm long x 50 mm wide x 3 mm thick, such that 135 mm of the 165 mm long length of the float glasses was attached via the intermediate film 71 made of a laminate having adhesive layers (II) 61 on both sides of a base layer (I) 62, to produce a laminated glass 50. The manufacturing procedure for the laminated glass was the same as that described in the Examples and Comparative Examples described later.
5, an iron plate 81 weighing 250 g was attached to the glass 51 side of the laminated glass 50 with an instant adhesive 91 to produce a laminated glass 100 with the iron plate attached. The laminated glass 100 with the iron plate attached was placed against a stand 111 and left for one week in a chamber at 100° C. After leaving it, the distance that the glass 51 had slipped down was measured and the distance was evaluated based on the following criteria, and this evaluation was used as an evaluation of heat creep resistance.
A: The distance that the glass 51 has slid down is 1 mm or less.
B: The distance that the glass 51 slipped down exceeded 1 mm.

[Synthesis Example 1: Synthesis of polyvinyl butyral resin (PVB-1)]
In a 5-liter glass vessel equipped with a reflux condenser, a thermometer, and an anchor-type stirring blade, 4000 g of ion-exchanged water and 400 g of polyvinyl alcohol (viscosity average polymerization degree 2000, saponification degree 94.0 mol%) were charged, and the temperature was raised to 95 ° C. to completely dissolve the polyvinyl alcohol. The obtained solution was gradually cooled to 10 ° C. over about 30 minutes while stirring at 120 rpm, and then 246 g of butyl aldehyde and 300 mL of a 20% aqueous hydrochloric acid solution were added. The temperature was then raised to 70 ° C. over 60 minutes, and the mixture was kept at 70 ° C. for 100 minutes, and then cooled to room temperature. The obtained resin was washed with ion-exchanged water, and then an aqueous sodium hydroxide solution was added to neutralize the remaining acid, and the resin was further washed with excess ion-exchanged water and dried to obtain a polyvinyl butyral resin (PVB-1). The above procedure was repeated to obtain an amount of polyvinyl butyral resin (PVB-1) required for the experiment. When the polyvinyl butyral resin (PVB-1) was analyzed in accordance with JIS K 6728, the average butyralization degree (average acetalization degree) was 76.0 mol %, the vinyl acetate unit content was 5.0 mol %, and the vinyl alcohol unit content was 19.0 mol %.

[Synthesis Example 2: Synthesis of polyvinyl butyral resin (PVB-2)]
In a 5-liter glass vessel equipped with a reflux condenser, a thermometer, and an anchor-type stirring blade, 4000 g of ion-exchanged water and 400 g of polyvinyl alcohol (viscosity average polymerization degree 900, saponification degree 94 mol%) were charged, and the temperature was raised to 95 ° C. to completely dissolve the polyvinyl alcohol. The obtained solution was gradually cooled to 7 ° C. over about 30 minutes while stirring at 120 rpm, and then 255 g of butyl aldehyde and 350 mL of a 20% aqueous hydrochloric acid solution were added. The temperature was then raised to 55 ° C. over 60 minutes, and the mixture was kept at 55 ° C. for 120 minutes, and then cooled to room temperature. The obtained resin was washed with ion-exchanged water, and then an aqueous sodium hydroxide solution was added to neutralize the remaining acid, and the resin was further washed with excess ion-exchanged water and dried to obtain a polyvinyl butyral resin (PVB-2). The above procedure was repeated to obtain an amount of polyvinyl butyral resin (PVB-2) required for the experiment. When the polyvinyl butyral resin (PVB-2) was analyzed in accordance with JIS K 6728, the average degree of butyralization (average degree of acetalization) was 76.0 mol %, the vinyl acetate unit content was 5.0 mol %, and the vinyl alcohol unit content was 19.0 mol %.

[Preparation of polycarbonate resin composition (PC-1)]
A polycarbonate resin "SDPOLYCA PCX" (manufactured by Sumika Polycarbonate Co., Ltd.) dried at 100°C for 24 hours and a commercially available polycyclohexane dimethylene terephthalate dried at 80°C for 24 hours were mixed so that the charge ratio of polycyclohexane dimethylene terephthalate was 39 mass% and Tg was 120°C, to prepare a resin composition (PC-1) containing a polycarbonate resin.

[Polycarbonate resin material (PC-2)]
"SDPOLYCA 301-4" (manufactured by Sumika Polycarbonate Co., Ltd.) dried at 100°C for 24 hours was used as the resin material (PC-2) constituting the substrate layer.

[Methacrylic resin composition (PMMA)]
A methacrylic resin composition "Parapet GR-00100" (manufactured by Kuraray Co., Ltd.) dried at 80°C for 24 hours was used as the resin material (PMMA) constituting the base layer.

[Preparation of polyvinyl butyral resin composition (PVB-3)]
83.0 parts by mass of polyvinyl butyral resin (PVB-1) dried at 60°C for 24 hours and 17.0 parts by mass of carboxylic acid polyester plasticizer "Kuraray Polyol P-510" (manufactured by Kuraray Co., Ltd.) containing 3-methyl-1,5-pentanediol adipate as the main component were melt-kneaded in a Labo Plastomill 4M150 (150°C, 60 rpm, 5 minutes) manufactured by Toyo Seiki Co., Ltd. to obtain a polyvinyl butyral resin composition (PVB-3). The above procedure was repeated to obtain the amount of polyvinyl butyral resin composition (PVB-3) required for the experiment.

[Preparation of polyvinyl butyral resin composition (PVB-4)]
A polyvinyl butyral resin composition (PVB-4) was obtained in the same manner as in the preparation of the polyvinyl butyral resin composition (PVB-3), except that the amounts of the polyvinyl butyral resin (PVB-1) and Kuraray Polyol P-510 were changed to 77.0 parts by mass and 23.0 parts by mass, respectively.

[Preparation of polyvinyl butyral resin composition (PVB-5)]
55.0 parts by mass of polyvinyl butyral resin (PVB-1) dried at 60°C for 24 hours, 40.0 parts by mass of polyvinyl butyral resin (PVB-2) dried at 60°C for 24 hours, and 5.0 parts by mass of Kuraray Polyol P-510 were melt-kneaded in a Labo Plastomill 4M150 (150°C, 60 rpm, 5 minutes) manufactured by Toyo Seiki Co., Ltd. to obtain a polyvinyl butyral resin composition (PVB-5). The above procedure was repeated to obtain an amount of polyvinyl butyral resin composition (PVB-5) required for the experiment.

[Preparation of Rolls of Resin Sheets Constituting Base Layers (I-1) to (I-7), (I-11), and (I'-1)]
Using a 45 mmφ single-screw extruder, a polycarbonate resin material (PC-2) was extruded from a single-layer T-die at a resin temperature of 280°C, taken up by a roll with a surface temperature of 140°C, and the end portion with a large thickness variation was cut off to obtain a roll of resin sheet having a width of 350 mm and the thickness shown in Table 1.

[Preparation of a roll of resin sheet constituting substrate layer (I-12)]
Using a 45 mmφ single-screw extruder, a methacrylic resin composition (PMMA) was extruded from a single-layer T-die at a resin temperature of 265°C, taken up by a roll with a surface temperature of 110°C, and the end with large thickness variation was cut off to obtain a roll of a resin sheet with a width of 350 mm and a thickness of 0.26 mm.

[Preparation of a roll of resin sheet constituting substrate layer (I-13)]
A roll of a resin sheet was obtained in the same manner as in the base layer (I-1), except that the polycarbonate resin composition (PC-1) was used instead of the polycarbonate resin material (PC-2).

[Roll of resin sheet constituting substrate layer (I'-2)]
A commercially available stretched polyethylene terephthalate film having a thickness of 0.13 mm, "Cosmoshine E5100" (manufactured by Toyobo Co., Ltd.), was used as a roll of the base layer (I'-2).

[Preparation of resin sheets constituting base layers (I'-3) to (I'-5)]
Using a 65 mmφ single screw extruder, polycarbonate resin material (PC-2) was extruded from a single layer T-die at a resin temperature of 280° C., taken up with a roll having a surface temperature of 140° C., and the end portion with large thickness variation was cut off to obtain a resin sheet having a width of 350 mm and a thickness as shown in Table 1. All of the resin sheets had a large bending rigidity and were difficult to wind into a roll, so the resin sheets were cut into lengths of about 1 m to obtain the resin sheets.

[Preparation of Rolls of Resin Sheets Constituting Adhesive Layers (II-3) to (II-5) and (II-13) and (II'-1) to (II'-4) and (II'-6)]
Using a 25 mφ single screw extruder "VGM25-28EX" (manufactured by G&M Engineering Company Limited), the polyvinyl butyral resin composition (PVB-3) or (PVB-5) shown in Table 1 was extruded from a single layer T-die at a resin temperature of 190°C to the thickness shown in Table 1, and taken up with a roll having a surface temperature of 20°C to obtain a roll of a resin sheet having a width of 300 mm.

[Preparation of adhesive layer (II-11)]
Using a 25 mφ single-screw extruder "VGM25-28EX" (manufactured by G&M Engineering Company Limited), 100 parts by mass of EVA resin (Ultrathene 635, manufactured by Tosoh Corporation), 3 parts by mass of Perbutyl E (t-butylperoxy-2-ethylhexyl monocarbonate, manufactured by Nippon Oil & Fats Co., Ltd.) as a crosslinking agent, and 1 part by mass of KBM503 (manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent were extruded from a single-layer T-die at a resin temperature of 80°C, and taken up by a roll having a surface temperature of 80°C to obtain a roll of resin sheet having a width of 300 mm and a thickness of 0.025 mm.

[Preparation of Adhesive Layer (II'-5)]
A non-yellowing thermoplastic polyurethane resin sheet, Argotec ST6050 (manufactured by SWM), was placed in a mold (30 cm long x 30 cm wide x 0.80 mm high) installed between two stainless steel plates (35 cm long x 35 cm wide). This was set in a heat press (manufactured by Shinto Metal Industry Co., Ltd.). The resin was heated at 130°C for 3 minutes without applying pressure to the non-yellowing thermoplastic polyurethane resin sheet. The resin sheet was then heat pressed at a pressure of 90 kgf/cm ² (about 8.8 MPa) for 180 seconds. Thereafter, the stainless steel plate and mold were immediately set in a cooling press at 23°C. Pressure was applied to the resin sheet while cooling it with the cooling press. A resin sheet of 30 cm long x 30 cm wide x 0.05 mm thick was obtained by cutting out the resin sheet in the mold.

[Example 1]
In a 10 L glass container, 2125 g of methyl acetate and 2125 g of methanol were mixed and cooled to room temperature. Then, 750 g of polyvinyl butyral resin composition (PVB-3) was added, and the contents were completely dissolved at room temperature to prepare a polyvinyl butyral resin composition solution. Next, a resin sheet was pulled out from the roll of the resin sheet constituting the base layer (I-1), and the polyvinyl butyral resin composition solution was applied thereon using a gravure coater so that the thickness after drying was 0.010 mm, and the resin sheet was dried in a drying oven with a drying temperature of 80 ° C., a conveying speed of 1 m / min, and a furnace length of about 1.5 m, and then wound up on a paper core with a diameter of 6 inches to obtain a roll of a resin sheet to which an adhesive layer (II-1) was applied on one side of the base layer (I-1). Similarly, the polyvinyl butyral resin composition solution was applied to the other surface of the base layer (I-1) (the surface not provided with the adhesive layer (II-1)) so that the thickness after drying was 0.010 mm, dried, and wound up on a paper core having a diameter of 6 inches to obtain a roll body. The resin sheet was pulled out from the obtained roll body, and passed through rolls at 140°C using a thermal lamination device (manufactured by Taisei Laminator Co., Ltd.) for pressure bonding, and then wound up on a paper core having a diameter of 6 inches to obtain a roll body of a laminate having adhesive layers (II-1) on both sides of the base layer (I-1). The conveying speed was 1.0 m/min, and the pressure was 0.15 MPa.
Next, the laminate was pulled out from the roll of the laminate, and the laminate was cut into a size of 305 mm x 610 mm. The cut laminate was conditioned for 24 hours in a constant temperature and humidity room (20 ° C, 65% RH) and placed between two flat float glasses having a thickness of 3.0 mm, a Young's modulus of 7.16 x 10 ⁴ MPa, and a size of 305 mm x 610 mm. After placing this in a rubber bag, it was put into a vacuum laminator (manufactured by Nisshinbo Mechatronics Inc.) and degassed under the conditions of a hot plate temperature of 165 ° C, a vacuum drawing time of 12 minutes, a press pressure of 50 kPa, and a press time of 17 minutes, thereby temporarily bonding the float glass and the laminate (interlayer film). Next, the temporarily bonded product taken out of the rubber bag was compressed in an autoclave to obtain a laminated glass. The autoclave conditions were a pressure of 12 bar and a temperature of 140 ° C for a total of 90 minutes or less.

[Example 2]
A laminated glass was produced in the same manner as in Example 1, except that a roll of the resin sheet constituting the base layer (I-2) was used instead of the roll of the resin sheet constituting the base layer (I-1).

[Examples 3 to 5 and 11 and Comparative Examples 1 to 2]
To obtain the configuration of each laminate shown in Table 1 or Table 2, resin sheets were pulled out from the roll of resin sheet constituting the base layer and the roll of resin sheet constituting the two adhesive layers, and the two adhesive layers were placed on both sides of the base layer, and the sheets were passed between rolls at 140°C using a thermal lamination device (manufactured by Taisei Laminator Co., Ltd.) to be pressed, and then wound up on a 6-inch paper core to obtain a roll of each laminate. The conveying speed was 1.0 m/min and the pressure was 0.15 MPa. Thereafter, each laminated glass was produced in the same manner as in Example 1, except that each obtained roll was used.

[Examples 6 to 7 and 12]
A polyvinyl butyral resin composition solution constituting an adhesive layer was applied to both sides of a base layer in the same manner as in Example 1, and then dried and heat-laminated to obtain a roll of a laminate having adhesive layers on both sides of a base layer, so as to obtain each laminate structure shown in Table 1. Thereafter, each laminated glass was produced in the same manner as in Example 1, except that each obtained roll was used.

[Example 8]
The polycarbonate resin composition (PC-1) which is the resin material constituting the base layer (I-8) was melted by a 65 mmφ single screw extruder (manufactured by Toshiba Machine Co., Ltd.), and the polyvinyl butyral resin composition (PVB-3) which is the resin material constituting the adhesive layer (II-8) was melted by a 150 mmφ single screw extruder (manufactured by Toshiba Machine Co., Ltd.), and the resin materials were co-extruded from a T die through a multi-manifold type die so that the adhesive layer (II-8) was disposed on both sides of the base layer (I-8), and wound up on a 6-inch paper core to obtain a roll body of a laminate provided with an adhesive layer (II-8) on both sides of the base layer (I-8). The film-forming temperature of both resin materials was 230 ° C., and the amount of discharged resin was adjusted so that the thickness of the base layer was 0.40 mm and the thickness of the adhesive layer was 0.025 mm per layer.
Next, a laminated glass was produced in the same manner as in Example 1, except that the obtained roll body was used.

[Example 9]
A roll of a laminate having adhesive layers (II-9) on both sides of a substrate layer (I-9) was obtained in the same manner as in Example 8, except that the polyvinyl butyral resin composition (PVB-4) was used instead of the polyvinyl butyral resin composition (PVB-3) and the thicknesses of the substrate layer and adhesive layer were changed as shown in Table 1.
Next, a laminated glass was produced in the same manner as in Example 1, except that the obtained roll body was used.

[Example 10]
A roll of a laminate having adhesive layers (II-10) on both sides of a substrate layer (I-10) was obtained in the same manner as in Example 8, except that the polyvinyl butyral resin composition (PVB-5) was used instead of the polyvinyl butyral resin composition (PVB-3) and the thickness of the adhesive layer was changed as shown in Table 1.
Next, a laminated glass was produced in the same manner as in Example 1, except that the obtained roll body was used.

[Example 13]
Resin sheets were drawn out from the roll of resin sheet constituting the base layer and the roll of resin sheet constituting the two adhesive layers so as to obtain the laminate configuration shown in Table 1. The thickness and shear relaxation modulus G ₁ (t) and G ₂ (t) of each layer were measured. Next, a roll of laminate and laminated glass were produced in the same manner as in Example 3, except that the base layer (I-13) and the two adhesive layers (II-13) were used. The thickness of the entire interlayer film was the thickness of the obtained laminate, and was measured with a thickness gauge.

[Comparative Examples 3 to 4]
The resin sheets constituting the base material layer were laminated so that two adhesive layers were disposed on both sides of the resin sheet constituting the base material layer to obtain the laminate configuration shown in Table 2, and the laminate was obtained by passing the laminate between rolls at 140°C using a thermal lamination device (manufactured by Taisei Laminator Co., Ltd.). The conveying speed was 1.0 m/min, and the pressure was 0.15 MPa. Thereafter, a laminated glass was produced in the same manner as in Comparative Example 1, except that the laminate obtained was used instead of the laminate pulled out from the laminate roll.

[Comparative Example 5]
A laminate was obtained in the same manner as in Comparative Example 3, except that the base layer (I'-5) and the two adhesive layers (II'-5) were used.
The obtained laminate was then cut to a size of 305 mm x 610 mm. The cut laminate was conditioned for 24 hours in a constant temperature and humidity room (20°C, 65% RH) and placed between two flat float glasses having a thickness of 3.0 mm, a Young's modulus of 7.16 x 10 ⁴ MPa, and dimensions of 305 mm x 610 mm. After placing this in a rubber bag, it was put into a vacuum laminator (manufactured by Nisshinbo Mechatronics Inc.) and degassed under the conditions of a hot plate temperature of 100°C, a vacuum drawing time of 12 minutes, a press pressure of 50 kPa, and a press time of 17 minutes, thereby temporarily bonding the float glass and the laminate (interlayer film). Next, the temporarily bonded product removed from the rubber bag was compressed in an autoclave to obtain a laminated glass. The autoclave conditions were a pressure of 6 bar and a temperature of 100°C for a total of 90 minutes or less.

[Comparative Example 6]
A laminated glass was produced in the same manner as in Example 3, except that no substrate layer was used and one adhesive layer (II'-6) was used as it was as an interlayer film.

The configurations of the laminates produced in the examples and comparative examples, as well as the evaluation results of the laminates, interlayer films, and laminated glass, are shown in Tables 1 and 2.

As shown in Table 1, the interlayer films in Examples 1 to 13 had a high shear transfer coefficient and high penetration resistance, and the laminated glass using these films had a small four-point bending deflection, a high effective glass thickness, and excellent thermal creep resistance. This indicates that the interlayer films in Examples 1 to 13 provide laminated glass with excellent penetration resistance and heat resistance, as well as sufficient strength (especially flexural strength) even in applications where the glass is used at high temperatures for long periods of time.
Furthermore, when the interlayer films in Examples 1 to 13 were produced as long resin sheets, they could be wound well around a core having a relatively small diameter of 6 inches. Furthermore, after unwinding, the interlayer film was less likely to retain a curling tendency, and was less likely to warp. Thus, the interlayer films in Examples 1 to 13 were excellent in handleability during the production of laminated glass, and improved work efficiency could be achieved.

The laminates in Examples 8 to 10 are embodiments in which the melt viscosity (η ₁ ) is within the range of 1×10 ² to 1×10 ⁴ Pa·s, the melt viscosities (η ₂ ) and (η ₃ ) are within the range of 1×10 ² to 1×10 ⁴ Pa·s, respectively, and the melt viscosity ratios η ₁ /η ₂ and η ₁ /η ₃ are within the range of 1.0 to 4.0. In addition, the thickness of the adhesive layer (II) is designed to be thinner than the thickness of the base layer (I). The laminates in Examples 8 to 10 were successfully formed by coextrusion.

Examples 10 and 13 are the same in the type and thickness of the resin material constituting the base layer, the type and thickness of the resin material constituting the adhesive layer, and the configuration of the interlayer (the interlayer is a single laminate). From the results in Table 1, it can be seen that the shear relaxation moduli G ₁ (t=f ^-1 ) and G ₂ (t=f ^-1 ) of the interlayer in Example 10 are equivalent to the shear relaxation moduli G ₁ (t) and G ₂ (t) of the interlayer in Example 13, respectively.

On the other hand, the interlayer films in Comparative Examples 1, 3 and 5, which did not have the specific shear relaxation modulus G ₁ (t=f ^-1 ) and G ₂ (t=f ^-1 ) and the specific bending rigidity, the interlayer film in Comparative Example 2, which did not have the specific shear relaxation modulus G ₁ (t=f ^-1 ) and G ₂ (t=f ^-1 ), the interlayer film in Comparative Example 4, which did not have the specific shear relaxation modulus G ₁ (t=f ^-1 ) and the specific bending rigidity, and the interlayer film in Comparative Example 6, which did not have the specific shear relaxation modulus G ₁ (t=f ^-1 ) and G ₂ (t=f ^-1 ) and did not have a substrate layer, had low shear transmission coefficients, and the laminated glass using these had large four-point bending deflections and low effective glass thicknesses. This shows that the interlayer films in Comparative Examples 1 to 6 result in laminated glass with insufficient strength in applications where the glass is used for a long period of time at high temperatures.
Moreover, Comparative Example 5 produced a laminated glass that was also inferior in heat resistance.
The laminates in Comparative Examples 3 to 5 could not be wound into a roll, which resulted in poor handling and poor work efficiency during the production of laminated glass.

The laminated glass of the present invention has excellent penetration resistance and heat resistance, and also has sufficient strength even in applications where it is used at high temperatures for long periods of time. Therefore, the laminated glass of the present invention can be suitably used as laminated glass for vehicle applications (e.g., automobile front glass, automobile side glass, automobile sunroof, automobile rear glass, glass for head-up displays, etc.) or for architectural and structural applications (e.g., building materials such as laminates for facades, exterior walls or roofs, panels, doors, windows, walls, roofs, sunroofs, soundproof walls, display windows, balconies, and handrail walls, conference room partition glass components, solar panels, etc.), particularly as laminated glass for architectural and structural applications where it is used at high temperatures for long periods of time.

Reference Signs List 11 T-die 12 First cooling roll 13 Second cooling roll 14 Third cooling roll 15 Take-up roll 16 Laminate 21 Inorganic glass 31 Adhesive layer (II)
32 Base layer (I)
41 Interlayer film 50 Laminated glass used for evaluating heat creep resistance 51 Float glass 52 Float glass 61 Adhesive layer (II)
62 Base layer (I)
71 Interlayer film 81 Iron plate 91 Instant adhesive 100 Laminated glass with iron plate bonded together 111 Stand

Claims (26)

An interlayer film used by being sandwiched between two sheets of inorganic glass,
The intermediate film includes a laminate including a substrate layer (I) containing one or more hard resins selected from the group consisting of acrylic resins, polycarbonate resins, polyester resins, polystyrene resins, polyolefin resins, polymethylpentene resins, cyclic polyolefin resins, and acrylonitrile-butadiene-styrene resins, and an adhesive layer (II) containing an adhesive resin selected from the group consisting of polyvinyl acetal resins, urethane resins, melamine-based resins, acrylic resins, epoxy-based resins, styrene-based thermoplastic elastomers, ethylene-vinyl acetate copolymers, polymethacrylic acid, poly(meth)acrylic acid esters, and ethylene-(meth)acrylic acid ester copolymers , on both sides of the substrate layer (I);
The following formula (1):
Shear relaxation modulus G(t=f ^-1 )=G'(f)－0.4G''(0.5f) (1)
[In formula (1), f is a frequency of 1.2×10 ⁻⁵ Hz, G′(f) is the shear storage modulus (MPa) at 50° C., and G″(0.5f) is the shear loss modulus (MPa) at 50° C.]
The shear relaxation modulus G ₁ (t=f ⁻¹ ) of the interlayer film is 0.80 MPa or more,
the shear relaxation modulus G 2 (t=f -1 ) of the interlayer film, represented by the above formula (1) [in formula (1), f is a frequency of 3.2×10 ^-9 Hz, G'(f) is the shear storage modulus (MPa) at 50° C., and G'_' ( ^0.5f ) is the shear loss modulus (MPa) at 50° C.], is 0.20 MPa or more,
The following formula (2):
The bending stiffness of the laminate at 25°C is 6 N·mm or more and 70 N·mm or less. The shear relaxation elastic modulus of each of the m base layers and 2m adhesive layers included in the intermediate film and the thickness ratio of each layer are used to determine the shear relaxation elastic modulus. The shear relaxation elastic modulus is expressed by the following formula (3):
[The shear relaxation modulus of each layer in formula (3) is the shear relaxation modulus at 50° C. and 1.2×10 ⁻⁵ Hz, and M is an integer of 1 to 7]
The shear relaxation modulus G ₁ (t) of the interlayer film is 0.80 MPa or more,
The interlayer film according to claim 1, wherein the shear relaxation modulus G 2 (t) of the interlayer film, which is represented by the above formula (3) [wherein the shear relaxation modulus of each layer in formula (3) is the shear relaxation modulus at 50° C. and _3.2 ×10 ⁻⁹ Hz, and M is an integer from 1 to 7], is 0.20 MPa or more. The intermediate film according to claim 1 or 2, wherein in the laminate, the thickness of the base layer (I) is greater than the thickness of either of the two adhesive layers (II). The intermediate film according to any one of claims 1 to 3, wherein in the laminate, the thickness of the base layer (I) is greater than the total thickness of the two adhesive layers (II). The above interlayer film was sandwiched between two pieces of float glass having a thickness of 3.0 mm and a Young's modulus of 7.16×10 ⁴ MPa, and in a four-point bending test with a support distance of 0.3 m,
The following formula (4):
[ _In formula (4), _hs = 0.5 × ( _h1 + _h2 ) + _{hv , Is} = _hs2 × ^h1 × _h2 ÷ ( _h1 + _h2 ), _h1 and _h2 are the thicknesses of the two float glasses (unit: mm), _hv is the thickness of the interlayer (unit: mm), E is the Young's modulus of the float glass (unit: MPa), G(t = f-1) is the above _G1 (t = f ^{-1 )} (unit: MPa), and a is the distance between the supports in the four-point bending test (unit: m)]
The shear transfer coefficient Γ ₁ of the interlayer film is 0.10 or more,
The interlayer film according to any one of claims 1 to 4, wherein the shear transfer coefficient Γ2 of the interlayer film represented by the above formula (4) [in formula (4), hs _{, Is} , _h1 , _h2 , _hv , E and a are as described above, and _G (t=f- ¹ ) is the above _G2 (t=f ^-1 ) (unit: MPa)] is 0.02 or more. The interlayer film according to any one of claims 1 to 5, wherein the interlayer film has a penetration resistance of 12 J or more measured in a drop weight impact test in accordance with ASTM D3763 under conditions of a measurement temperature of 23°C, ^a load of 2 kg, and an impact speed of 9 m s The interlayer film according to any one of claims 1 to 6, wherein the hard resin is selected from the group consisting of an acrylic resin and a polycarbonate resin. The interlayer film according to any one of claims 1 to 7 , wherein the substrate layer (I) contains a polycarbonate resin as a hard resin. The interlayer film according to any one of claims 1 to 8, wherein the acrylic resin is a methacrylic resin. The interlayer film according to any one of claims 1 to 9, wherein the adhesive resin is selected from the group consisting of polyvinyl acetal resin and ethylene-vinyl acetate copolymer. The interlayer film according to any one of claims 1 to 10 , wherein in the laminate, at least one adhesive layer (II) contains a polyvinyl acetal resin as an adhesive resin. The interlayer film according to any one of claims 1 to 11, wherein the polyvinyl acetal resin is a polyvinyl butyral resin. The interlayer film according to any one of claims 1 to 12 , wherein in the laminate, at least one adhesive layer (II) further contains a plasticizer. 14. The interlayer film according to claim 13, wherein the plasticizer is at least one selected from the group consisting of carboxylate-based plasticizers, phosphate-based plasticizers, organic phosphite-based plasticizers, carboxylate polyester-based plasticizers, carbonate polyester-based plasticizers, polyalkylene glycol-based plasticizers, and ester compounds of hydroxycarboxylic acids and polyhydric alcohols . The interlayer film according to any one of claims 1 to ¹⁴ , wherein in the laminate, the melt viscosity (η ₁ ) of the resin material constituting the base layer (I) is 1×10 ² Pa·s or more and 1×10 4 Pa·s or less, the melt viscosities (η ₂ ) and (η ₃ ) of the resin materials constituting each adhesive layer (II) are, respectively, 1×10 ² Pa·s or more and 1×10 ⁴ Pa·s or less, and the melt viscosity ratios (η ₁ /η ₂ ) and (η ₁ /η ₃ ) are 1.0 or more and 4.0 or less, as measured in accordance with JIS K 7199 at a temperature of ²³⁰ °C and a shear rate of 60 s- 1 . A method for producing the interlayer film according to any one of claims 1 to 15 , comprising providing an adhesive layer (II) on both sides of a substrate layer (I) by coextrusion to produce a laminate. A laminated glass in which inorganic glass, an interlayer film, and inorganic glass are laminated in this order,
The intermediate film includes a laminate including a substrate layer (I) containing one or more hard resins selected from the group consisting of acrylic resins, polycarbonate resins, polyester resins, polystyrene resins, polyolefin resins, polymethylpentene resins, cyclic polyolefin resins, and acrylonitrile-butadiene-styrene resins, and an adhesive layer (II) containing an adhesive resin selected from the group consisting of polyvinyl acetal resins, urethane resins, melamine-based resins, acrylic resins, epoxy-based resins, styrene-based thermoplastic elastomers, ethylene-vinyl acetate copolymers, polymethacrylic acid, poly(meth)acrylic acid esters, and ethylene-(meth)acrylic acid ester copolymers , on both sides of the substrate layer (I);
The following formula (1):
Shear relaxation modulus G(t=f ^-1 )=G'(f)－0.4G''(0.5f) (1)
[In formula (1), f is a frequency of 1.2×10 ⁻⁵ Hz, G′(f) is the shear storage modulus (MPa) at 50° C., and G″(0.5f) is the shear loss modulus (MPa) at 50° C.]
The shear relaxation modulus G ₁ (t=f ⁻¹ ) of the interlayer film is 0.80 MPa or more,
the shear relaxation modulus G 2 (t=f -1 ) of the interlayer film, represented by the above formula (1) [in formula (1), f is a frequency of 3.2×10 ^-9 Hz, G'(f) is the shear storage modulus (MPa) at 50° C., and G'_' ( ^0.5f ) is the shear loss modulus (MPa) at 50° C.], is 0.20 MPa or more,
The following formula (2):
The bending rigidity of the laminate at 25°C is 6 N mm or more and 70 N mm or less. The laminated glass according to claim 17 , wherein in the laminate, the thickness of the substrate layer (I) is greater than the total thickness of the two adhesive layers (II). 19. The laminated glass according to claim 17 or 18, wherein the hard resin is selected from the group consisting of an acrylic resin and a polycarbonate resin. The laminated glass according to any one of claims 17 to 19, wherein the acrylic resin is a methacrylic resin. The laminated glass according to any one of claims 17 to 20, wherein the adhesive resin is selected from the group consisting of polyvinyl acetal resin and ethylene-vinyl acetate copolymer. The laminated glass according to any one of claims 17 to 21 , wherein in the laminate, at least one adhesive layer (II) contains a polyvinyl acetal resin as an adhesive resin. The laminated glass according to any one of claims 17 to 22, wherein the polyvinyl acetal resin is a polyvinyl butyral resin. The laminated glass according to any one of claims 17 to 23 , wherein in the laminate, at least one of the adhesive layers (II) further contains a plasticizer. 25. The laminated glass according to claim 24, wherein the plasticizer is at least one selected from the group consisting of carboxylate-based plasticizers, phosphate-based plasticizers, organic phosphite-based plasticizers, carboxylate polyester-based plasticizers, carbonate polyester-based plasticizers, polyalkylene glycol-based plasticizers, and ester compounds of hydroxycarboxylic acids and polyhydric alcohols . 26. The laminate according to claim 17, wherein the resin material constituting the base material layer (I) has a melt viscosity (η ₁ ) of 1×10 ² Pa·s or ^more and 1×10 ⁴ Pa·s or less, the resin materials constituting each adhesive layer (II) have melt viscosities (η ₂ ) and (η ₃ ) of 1×10 ² Pa·s or more and 1×10 ⁴ Pa·s or less, respectively, and the melt viscosity ratios (η ₁ /η ₂ ) and (η ₁ /η ₃ ) are 1.0 or more and 4.0 or less, as measured in accordance with JIS K 7199 at a temperature of 230 ° C. and a shear rate of 60 s -1.