JP7629393B2 - Laminated Glass - Google Patents

Description

The present invention relates to laminated glass, and more particularly to laminated glass equipped with a light control film.

A type of window glass used in vehicles is smart glass, which has a light-control film sealed inside the laminated glass, allowing the transmittance to be electrically switched by turning a power switch on and off.

In smart glass, in order to protect the ends of the light-control film from the external environment, the light-control film is often cut smaller than the size of the glass plate or intermediate adhesive layer, and the ends are covered with the intermediate adhesive layer before being enclosed in the laminated glass. Specifically, a frame-shaped intermediate adhesive layer is placed around the periphery of the light-control film, which is then sandwiched between two intermediate adhesive layers and further sandwiched between a pair of glass plates (see, for example, Patent Document 1).

However, using a frame-shaped intermediate adhesive layer posed problems such as poor workability during the lamination process and increased costs due to the increased amount of intermediate adhesive layer used.

In existing technology, when a thin functional film, for example an infrared reflective film, is enclosed in laminated glass, it is common to encapsulate it without using a frame-shaped intermediate adhesive layer (see, for example, Patent Document 2). However, in the case of a light-control film, the light-control material is usually sandwiched between two plastic films, and it tends to be thicker than other functional films. If a frame-shaped intermediate adhesive layer is not used, air will remain or bubbles will form, resulting in poor appearance. As a result of extensive research, the present inventors have found that the above problem can be solved by controlling the thickness of the light-control film and its positional relationship in the laminated glass.

Patent No. 5666128 JP 2017-186179 A

The present invention aims to provide laminated glass having a light-control film, which can protect the ends of the light-control film without compromising the appearance and has improved productivity.

The laminated glass of the present invention is
A pair of glass plates facing each other;
a pair of intermediate adhesive layers located between the pair of glass plates and in contact with the pair of glass plates, respectively;
and a light control film capable of switching visible light transmittance, the light control film being located between the pair of intermediate adhesive layers, the laminated glass being approximately polygonal in plan view, and at least one side of the outer periphery of the laminated glass satisfying the following requirements (i-1) to (i-3).
(i-1) The outer periphery of the light control film is located a distance w [mm] inward from the outer periphery of the laminated glass in a plan view.
(i-2) When the thickness of the light-controlling film is ts [mm] and the total thickness of the pair of intermediate adhesive layers is ti [mm], the w, ti and ts satisfy the following formula 1.

0<w/ti<7/ts Formula 1
(i-3) The pair of intermediate adhesive layers contact each other in a region from the outer periphery of the laminated glass to the outer periphery of the light control film.

According to the present invention, in a laminated glass having a light-controlling film, the edge of the light-controlling film is protected, and the laminated glass can be provided with good productivity without impairing the appearance of the laminated glass.

FIG. 1 is a front view of an example of an embodiment of laminated glass of the present invention. FIG. 2 is a cross-sectional view taken along line XX of the laminated glass shown in FIG. 1 is a table showing evaluation results of examples and comparative examples.

The following describes embodiments of the present invention. Note that the present invention is not limited to these embodiments, and these embodiments may be modified or altered without departing from the spirit and scope of the present invention.

The laminated glass of the present invention includes a pair of glass plates facing each other, a pair of intermediate adhesive layers located between the pair of glass plates and in contact with the pair of glass plates, respectively, and a light control film capable of switching visible light transmittance located between the pair of intermediate adhesive layers, the laminated glass being approximately polygonal in a plan view, and at least one side of a periphery of the laminated glass satisfies the following requirements (i-1) to (i-3):
(i-1) The outer periphery of the light control film is located a distance w [mm] inward from the outer periphery of the laminated glass in a plan view.
(i-2) When the thickness of the light-controlling film is ts [mm] and the total thickness of the pair of intermediate adhesive layers is ti [mm], the w, ti and ts satisfy the following formula 1.

0<w/ti<7/ts Formula 1
(i-3) The pair of intermediate adhesive layers contact each other in a region from the outer periphery of the laminated glass to the outer periphery of the light control film.

In this specification, the edge means the ridge line formed by joining two surfaces, and the periphery means an area having a certain width from the edge of a surface toward the center of the surface. In laminated glass, the edge means the outer periphery of the main surface of the laminated glass. The thickness of laminated glass measured at the edge is the distance from the edge of one main surface of the laminated glass to the edge of the other main surface at the measurement position. The thickness of laminated glass measured at the edge is also called the edge thickness of laminated glass.

In the present invention, the outer periphery of the main surface of the laminated glass coincides with the outer periphery of the main surface of the glass sheets that constitute the laminated glass. In this specification, the outer periphery side of the main surfaces of the laminated glass and the glass sheets when viewed from the center is called the outside, and the central side when viewed from the outer periphery is called the inside.

In this specification, "approximately the same shape and size" means that the shape and size are the same as seen by the human eye. For example, when two things are "approximately the same shape and size," this also includes a case where one has an outer circumferential shape with no irregularities such as notches, while the other has an outer circumferential shape with fine notches or the like in some parts. In other cases, "approximately" has the same meaning as above. Also, in this specification, "to" indicating a numerical range includes the upper and lower limit numerical values.

Hereinafter, an embodiment of the laminated glass of the present invention will be described with reference to the drawings. Fig. 1 is a front view of an example of an embodiment of the laminated glass of the present invention, and Fig. 2 is a cross-sectional view of the laminated glass shown in Fig. 1 taken along line X-X.

1 and 2, laminated glass 10A comprises a pair of glass plates 1A, 1B facing each other, and a pair of intermediate adhesive layers 2A, 2B that contact the facing surfaces of the pair of glass plates 1A, 1B, respectively. In laminated glass 10A, the pair of glass plates 1A, 1B and the pair of intermediate adhesive layers 2A, 2B are substantially quadrilateral in plan view, and have main surfaces of substantially the same shape and size.

The shape of the laminated glass of the embodiment in a plan view is approximately polygonal. Approximately polygonal includes shapes in which the corners may have a radius of curvature of approximately 1000 mm or less. The number of corners of the polygon can be 3 to 8, and is selected appropriately depending on the application of the laminated glass. The shape of the laminated glass of the embodiment in a plan view is preferably approximately quadrilateral.

The laminated glass 10A further has a light control film 3 capable of switching visible light transmittance between the pair of intermediate adhesive layers 2A, 2B. The area of the main surface of the light control film 3 is smaller than the area of the main surfaces of the glass plates 1A, 1B, and the light control film 3 is disposed between the intermediate adhesive layers 2A, 2B such that the outer periphery of the main surface of the light control film 3 is located inside the outer periphery of the main surfaces of the glass plates 1A, 1B.

The outer periphery of the laminated glass 10A coincides with the outer periphery of the glass plates 1A and 1B. In the laminated glass 10A, the outer periphery of the light control film 3 is located a distance w [mm] inside from the outer periphery of the laminated glass 10A in a plan view (satisfying requirement (i-1)). The opposing main surfaces of the intermediate adhesive layer 2A and the intermediate adhesive layer 2B are in contact with each other in a frame-shaped region from the outer periphery of the laminated glass 10A to the outer periphery of the light control film 3 (satisfying requirement (i-3)). In other words, in the laminated glass 10A, there is no frame layer consisting of the third intermediate adhesive layer on the outside of the light control film 3. The width of this region corresponds to the above-mentioned distance w.

In the laminated glass 10A, the thickness of the light control film 3 is ts [mm], the thicknesses of the intermediate adhesive layers 2A and 2B are ti1 [mm] and ti2 [mm], respectively, and the thicknesses of the glass plates 1A and 1B are tg1 [mm] and tg2 [mm], respectively. The total thickness of the intermediate adhesive layers 2A and 2B is ti [mm].

The thickness of each component of the laminated glass is approximately constant within the plane, and the position at which the thickness is measured is not particularly limited. However, as described below, the thickness of the intermediate adhesive layer at the ends may decrease depending on the manufacturing method. Therefore, the position at which the thickness of each component of the laminated glass is measured should be at least 50 mm inside from the end of the laminated glass. The thickness is measured by a conventional method, for example, with a vernier caliper or a micrometer. An example of a micrometer is the Mitutoyo Digimatic Linear Micrometer 406-250 OMV25M.

The laminated glass 10A, which is an embodiment of the laminated glass of the present invention, has w, ti and ts that satisfy the following formula 1 (satisfies requirement (i-2)).

0<w/ti<7/ts Formula 1
In the laminated glass of the embodiment, the relationship between w, ti, and ts preferably satisfies the following formula 2. In this case, ts is 0.25 mm or more. Hereinafter, this requirement is also referred to as requirement (i-4).

0<w/ti<4.5/ts Formula 2
In the laminated glass of the embodiment, it is sufficient that at least one side of the outer periphery satisfies all of the requirements (i-1) to (i-3). It is preferable that at least two sides of the outer periphery of the laminated glass of the embodiment satisfy all of the requirements (i-1) to (i-3), and it is preferable that the entire periphery satisfies all of the requirements (i-1) to (i-3). In either case, it is more preferable that the requirement (i-4) is further satisfied.

The laminated glass 10A shown in Figures 1 and 2 is an example that satisfies all of requirements (i-1) to (i-3) around the entire periphery, and preferably satisfies requirement (i-4). The w in such laminated glass 10A, corresponding to the entire periphery of the laminated glass and the entire periphery of the light control film, satisfies formula 1, and preferably satisfies formula 2. As long as formula 1 is satisfied, and preferably within the range of formula 2, w may be different on each side of the periphery of the laminated glass 10A, and there may be portions within one side where w is different. The above aspects are also the same when the laminated glass is a polygon other than the approximately quadrilateral shown in Figure 1, for example.

In the laminated glass of the embodiment, on at least one side that satisfies requirements (i-1) to (i-3), and preferably on all sides, w is preferably 100 mm or less, more preferably 50 mm or less, even more preferably 20 mm or less, and even more preferably 10 mm or less. When w is equal to or greater than the above value, the area occupied by the light-controlling film is large, making it possible to control the visible light transmittance over a wide area and providing excellent design. Furthermore, in the laminated glass of the embodiment, on at least one side that satisfies requirements (i-1) to (i-3), and preferably on all sides, w is preferably 1 mm or more, more preferably 3 mm or more, and particularly preferably 5 mm or more, from the viewpoint of protecting the ends of the light-controlling film.

For example, in laminated glass 10A, if the total thickness ti of intermediate adhesive layers 2A and 2B is 0.8 mm and the thickness ts of light control film 3 is 0.35 mm, w that satisfies formula 1 is less than 16.0 mm, and w that satisfies formula 2 is less than 11.4 mm.

The laminated glass of the embodiment satisfies requirements (i-1) to (i-3), and preferably also satisfies requirement (i-4), thereby protecting the ends of the light-control film from the external environment and suppressing defects in appearance due to air remaining inside the laminated glass. This suppresses deterioration of the peripheral parts of the light-control film when used over long periods of time, resulting in a highly reliable laminated glass. Furthermore, since no frame-shaped intermediate adhesive layer is used, the process is easy to work with and economical, resulting in good productivity.

As shown in Figures 1 and 2, when the thickness of the laminated glass 10A measured at the end of the laminated glass 10A indicated by measurement point E in Figure 1 is T1, and the thickness of the laminated glass 10A measured at a position 50 mm inside from the end indicated by measurement point E (measurement point I in Figure 1) is T2, it is preferable that T2 - T1 is 0.28 mm or less. When T2 - T1 is in the above range, residual stress inside the laminated glass is small, and defects such as peeling and foaming are unlikely to occur. T2 - T1 is more preferably 0.2 mm or less, and even more preferably 0.15 mm or less.

The thicknesses T1 and T2 are measured by a conventional method, for example, with a vernier caliper or a micrometer. An example of a micrometer is the Mitutoyo Digimatic Linear Micrometer 406-250 OMV25M.

The phenomenon of the thickness of the laminated glass becoming smaller at the edges occurs because, as described below, during the manufacturing process of the laminated glass 10A, a large compressive force is applied to the edges of the laminate due to the processes of degassing the periphery of the laminate of the glass sheets 1A and 1B, the intermediate adhesive layers 2A and 2B, and the light control film 3, and of heating and pressing the laminate. As a result, in the resulting laminated glass 10A, the restoring forces of the glass sheets 1A and 1B act in a direction in which the edges expand (in the direction shown by the arrows in Figure 2) so that the thickness becomes the same as the thickness on the inside, and the thickness increases from the time of manufacture. For the sake of explanation, Figure 2 shows the characteristics of the actual product in an exaggerated manner.

The thickness of the laminated glass obtained through the above manufacturing process is generally uniformly smaller at the ends than on the inside over the entire circumference of the laminated glass. Therefore, in the laminated glass of the embodiment of the present invention, the thickness can be measured at least at two points, an arbitrary point on the end (measurement point E in laminated glass 10A) and a position 50 mm inward from the end (measurement point I in laminated glass 10A), as exemplified in laminated glass 10A. The arbitrary point on the end may be any point on the circumference of the laminated glass.

Note that, for example, if the measurement point is on a straight side of the periphery of the laminated glass, the position 50 mm inward from the measurement point of the edge thickness is a position 50 mm inward from the measurement point on the line perpendicular to the measurement point on that side. If the periphery is curved, the position is a position 50 mm inward from the measurement point on the perpendicular line to the tangent to the measurement point. In Figure 1, the position 50 mm inward from the periphery of the laminated glass 10A is shown by frame line M. In laminated glass 10A, if any one point on the periphery is set as measurement point E for the edge thickness, a point on frame line M where the above relationship holds for measurement point E is measurement point I 50 mm inward from the edge.

Hereinafter, each element constituting the laminated glass 10A will be described.
[Glass plate]
The glass plates 1A and 1B used in the laminated glass 10A according to the embodiment of the present invention may be made of transparent inorganic glass or organic glass (resin). As the inorganic glass, ordinary soda-lime glass (also called soda-lime silicate glass), borosilicate glass, alkali-free glass, quartz glass, etc. may be used without any particular limitation. Among these, soda-lime glass is particularly preferred. The forming method is also not particularly limited, but for example, float plate glass formed by a float method or the like is preferred. In the case of inorganic glass, the surface stress may be caused by a strengthening treatment such as physical strengthening or chemical strengthening.

Examples of organic glass (resin) include polycarbonate resin, polystyrene resin, aromatic polyester resin, acrylic resin, polyester resin, polyarylate resin, polycondensation product of halogenated bisphenol A and ethylene glycol, acrylic urethane resin, halogenated aryl group-containing acrylic resin, etc. Among these, polycarbonate resin such as aromatic polycarbonate resin and acrylic resin such as polymethyl methacrylate acrylic resin are preferred, and polycarbonate resin is more preferred. Furthermore, among polycarbonate resins, bisphenol A polycarbonate resin is particularly preferred. The glass plate may be composed of two or more of the above-mentioned resins.

The glass may be a colorless transparent material to which no coloring components are added, or a colored transparent material that is colored to the extent that the effect of the present invention is not impaired. Furthermore, one type of glass or a combination of two or more types of glass may be used, for example, a laminated substrate having two or more layers. Although it depends on the application location of the laminated glass, inorganic glass is preferable as the glass.

The pair of glass plates 1A and 1B used in the laminated glass 10A may be made of different materials. When the laminated glass 10A is installed in a vehicle or building, it is preferable that the glass plate located on the vehicle interior side or the interior side is soda-lime glass, and contains 0.4 mass% or more of iron in the composition as the total iron amount based on _oxide , calculated as _Fe2O3 . When the iron content of the glass plate on the vehicle interior side or the interior side is within the above range, the haze of the light control film is high, and even if the haze is 5% or more, for example, the haze is difficult to see from the vehicle interior side or the interior side, which is preferable.

The thicknesses tg1 and tg2 of the glass plates 1A and 1B can be appropriately selected depending on the application location of the laminated glass 10A, but generally, each is preferably independently 0.2 to 5 mm. From the viewpoint of achieving both weight reduction and rigidity of the laminated glass, 0.5 to 5 mm is more preferable, 1.1 to 3.5 mm is even more preferable, and 1.6 to 3.0 mm is particularly preferable. The glass plates 1A and 1B may have a three-dimensional curvature from the viewpoint of the design or functionality of the location where they are installed.

The plate thicknesses tg1 and tg2 of the pair of glass plates 1A and 1B may be the same or different. When the plate thicknesses of the glass plates 1A and 1B are different, it is preferable that the plate thickness of the glass plate located on the inside when the laminated glass 10A is installed in a window, for example, the glass plate located on the inside of the car in the case of an automobile window glass, or the glass plate located on the indoor side in the case of a building window glass, is smaller than the plate thickness of the glass plate located on the outside. When the plate thicknesses of the glass plates are in the above relationship, heat generated from the light control film or heat due to sunlight is easily released to the inside of the car or indoor side, so that deterioration of the light control film due to heat can be suppressed.

Furthermore, the glass plates 1A and 1B may be coated on their exposed surfaces to the atmosphere with a coating that provides water repellency, hydrophilicity, anti-fogging, low radiation, ultraviolet absorption, etc. In addition, the opposing surfaces of the glass plates 1A and 1B may be coated with a functional coating such as an infrared shielding coating or a conductive coating. Providing a low-reflection film on the vehicle interior or interior side of the laminated glass 10A is preferable because it can prevent reflections on the glass surface, especially at night, and provides a good design.

When the opposing surfaces of the glass plates 1A and 1B have the above-mentioned functional coating, the intermediate adhesive layers 2A and 2B described below are configured to contact the functional coating on the opposing surfaces of the glass plates 1A and 1B.
[Intermediate adhesive layer]
The pair of intermediate adhesive layers 2A, 2B in the laminated glass 10A have main surfaces of approximately the same shape and size as the main surfaces of the glass plates 1A, 1B. The intermediate adhesive layers 2A, 2B are provided so as to contact the opposing surfaces of the glass plates 1A, 1B, respectively, while sandwiching the light control film 3. In this way, the intermediate adhesive layers 2A, 2B have the function of bonding the light control film 3 between the pair of glass plates 1A, 1B via the intermediate adhesive layers 2A, 2B, and integrating them into the laminated glass 10A.

Here, specific examples of intermediate adhesive layers 2A and 2B include compositions containing the following thermoplastic resins as their main components, which are formed into sheets having main surfaces of approximately the same shape and dimensions as the main surfaces of glass plates 1A and 1B.

There are no particular limitations on the thermoplastic resin, so long as it can be integrated when a composition containing it as the main component is formed into a sheet-like film as a pair of intermediate adhesive layers 2A, 2B, sandwiched between a pair of glass plates 1A, 1B, heated and pressed to form laminated glass 10A. The optical performance required varies depending on the characteristics of the light-control film to be enclosed in the laminated glass, but the transmittance of the intermediate adhesive layer is preferably such that a visible light transmittance of 80% or more can be achieved when combined with only ordinary colorless and transparent glass to form laminated glass.

Specific examples of thermoplastic resins include polyvinyl acetal resins such as polyvinyl butyral resin (PVB), polyvinyl chloride resins, saturated polyester resins, polyurethane resins, ethylene-vinyl acetate copolymer resins (EVA), ethylene-ethyl acrylate copolymer resins, ionomer resins, and cycloolefin polymers (COP), which have traditionally been used for intermediate adhesive layers. Of these, PVB, EVA, polyurethane resins, ionomer resins, and COP are preferred. These thermoplastic resins may be used alone or in combination of two or more types.

The thermoplastic resin for the intermediate adhesive layer of the laminated glass is selected in consideration of the balance of various properties such as transparency, weather resistance, strength, adhesive strength, penetration resistance, impact energy absorption, moisture resistance, heat insulation, and sound insulation depending on the application. From the viewpoint of these conditions, among the above thermoplastic resins, a resin composition in which the vinyl acetate unit in an ethylene-vinyl acetate copolymer is saponified, and an ethylene-vinyl acetate copolymer resin composition characterized by containing an organo-layered clay, a silane coupling agent, etc. in an ethylene-vinyl acetate copolymer as described in Japanese Patent No. 5625781 are preferred. By containing an organo-layered clay, the moisture permeability can be significantly reduced compared to a normal ethylene-vinyl acetate copolymer resin composition. In addition, a resin composition containing a modified block copolymer hydrogenated product described in Japanese Patent Publication No. 2015-821 can also be preferably used.

The intermediate adhesive layer preferably has a minimum storage modulus of 2.0 x 10 ⁶ Pa or less in a temperature range of 90 to 120°C in dynamic viscoelasticity measurement at a measurement frequency of 10 Hz (hereinafter referred to as requirement (ii-1)). When the intermediate adhesive layer satisfies requirement (ii-1), it has a predetermined flexibility in the temperature range in which heat and pressure bonding is performed. As a result, the pair of intermediate adhesive layers have shape followability from the region in contact with the peripheral portion of the light control film to the region in contact with each other, that is, over the frame-shaped region of width w from the outer periphery of the laminated glass to the outer periphery of the light control film, facilitating sufficient bonding without leaving air.

The minimum value of the storage modulus in the intermediate adhesive layer is more preferably 8.0×10 ⁵ Pa or less, and even more preferably 5.0×10 ⁵ Pa or less. From the viewpoint of ensuring a predetermined rigidity in the temperature range in which thermocompression bonding is performed, the maximum value of the storage modulus in the intermediate adhesive layer is preferably 2.0×10 ⁵ Pa or more.

To adjust the storage modulus of the intermediate adhesive layer, for example, the unit amount of vinyl acetate in the thermoplastic resin constituting the intermediate adhesive layer can be increased to lower the storage modulus of EVA. Similarly, the storage modulus of PVB can be lowered by adjusting the composition to increase the amount of plasticizer.

In addition, with regard to ionomer resins, for example, in ionomer resins in which a copolymer of ethylene and (meth)acrylic acid, (meth)acrylic acid esters, etc. is crosslinked with metal ions, the storage modulus can be reduced by increasing the ratio of (meth)acrylic acid or (meth)acrylic acid esters to ethylene.

In COP, for example, a resin composition containing a modified hydrogenated block copolymer [3] obtained by introducing alkoxysilyl groups into a hydrogenated block copolymer [2] obtained by hydrogenating 90% or more of all unsaturated bonds in a block copolymer [1] having at least two polymer blocks [A] mainly composed of repeating units derived from an aromatic vinyl compound and at least one polymer block [B] mainly composed of repeating units derived from a chain-like conjugated diene compound, in which the ratio of wA to wB (wA:wB) is 30:70 to 60:40, where wA is the weight fraction of all polymer blocks [A] in the entire block copolymer and wB is the weight fraction of all polymer blocks [B] in the entire block copolymer, can reduce the storage modulus by lowering the proportion of wA.

In this way, by adjusting the storage modulus of the thermoplastic resin constituting the intermediate adhesive layer, an intermediate adhesive layer that satisfies requirement (1) is obtained.

For the intermediate adhesive layer, a material that does not affect the function of the light-control film during manufacturing or use is preferable. Therefore, it is preferable that the thermoplastic resin does not contain a plasticizer, or, if the thermoplastic resin contains a plasticizer, it contains a plasticizer that does not affect the light-control film.

Furthermore, the heating temperature during molding of the laminated glass is set according to the thermoplastic resin for the intermediate adhesive layer, but if the heating temperature is equal to or higher than the heat resistance temperature of the light control film, the light control film may not function adequately when laminated glass is formed. For this reason, it is preferable to select a thermoplastic resin for the intermediate adhesive layer so that the molding temperature of the laminated glass is equal to or lower than the heat resistance temperature of the light control film used.

As described above, a thermoplastic resin-containing composition containing the above-mentioned thermoplastic resin as a main component is used to prepare the intermediate adhesive layers 2A and 2B. The thermoplastic resin-containing composition may contain one or more of various additives such as infrared absorbers, ultraviolet absorbers, fluorescent agents, adhesion regulators, coupling agents, surfactants, antioxidants, heat stabilizers, light stabilizers, dehydrating agents, antifoaming agents, antistatic agents, and flame retardants, depending on various purposes, as long as the effects of the present invention are not impaired. These additives are uniformly contained throughout the intermediate adhesive layers 2A and 2B.

The thicknesses ti1 and ti2 of the intermediate adhesive layers 2A and 2B may satisfy formula 1 in terms of the total thickness ti in relation to w and ts. Specifically, similar to the intermediate adhesive layers normally used for laminated glass, the thickness per layer is preferably 0.3 to 0.8 mm, and the total thickness of the two layers is preferably 0.6 to 1.6 mm. If the thicknesses ti1 and ti2 per layer of the intermediate adhesive layer are each less than 0.3 mm, or the total thickness ti of the two layers is less than 0.6 mm, the strength may be insufficient, and peeling may occur easily if the glass mismatch is large. If the total thickness ti of the intermediate adhesive layers 2A and 2B exceeds 1.6 mm, the weight becomes large, which may cause problems when assembled to a vehicle.

The thicknesses ti1 and ti2 of the intermediate adhesive layers 2A and 2B may be the same or different. When the thicknesses of the intermediate adhesive layers 2A and 2B are different, it is preferable that the thickness of the intermediate adhesive layer located on the inner glass sheet when the laminated glass 10A is installed in a window, for example, the thickness of the intermediate adhesive layer located on the inner side of the car in the case of an automobile window glass, or the thickness of the intermediate adhesive layer located on the indoor side in the case of a building window glass, is smaller than the thickness of the intermediate adhesive layer located on the outer side. When the thicknesses of the intermediate adhesive layers are in the above relationship, heat generated from the light-control film or heat due to sunlight is easily released to the inner side of the car or indoor side, so that deterioration of the light-control film due to heat can be suppressed.

The intermediate adhesive layers 2A and 2B are not limited to a single-layer structure. The intermediate adhesive layers 2A and 2B may be the same, but are not necessarily the same, and can be selected independently of each other to have a single-layer structure or a multi-layer structure.

Incidentally, when the intermediate adhesive layer is prepared as an adhesive film or the like during the manufacture of laminated glass, it is preferable that the intermediate adhesive layer has an embossment. Usually, the material film that becomes the intermediate adhesive layer of laminated glass has an embossment, and when the material film is sandwiched between glass plates to form a laminate and then heat-pressed, the embossment functions as an air passage, and heat-pressed bonding is performed while the air between the layers of the laminate is sufficiently exhausted, and finally the embossment in the material film disappears to form an intermediate adhesive layer, and a high-quality laminated glass without residual air bubbles is obtained.
[Light control film]
As the light control film 3, light control films used in smart glass and the like, having a thickness ts of 0.1 mm to 1 mm, preferably 0.1 mm to 0.7 mm, more preferably 0.1 mm to 0.4 mm, can be used. In general, if the thickness is less than 0.1 mm, it is difficult to handle when preparing laminated glass, and if it is more than 1 mm, the rigidity of the substrate increases and it becomes difficult to follow the curved surface. If ts is within this range, the range of w can be set to a preferred range so as to satisfy formula 1 or formula 2 within the above range of ti.

Here, in the laminated glass of the embodiment, it is preferable from the viewpoint of design that the ratio of the area of the light control film to the area of the laminated glass in a plan view is 0.7 or more. If it is less than 0.7, the frame-like area may become too wide, which may impair the appearance.

As the light control film 3, for example, a suspended particle device (SPD) film can be used. As the SPD film, a general SPD film can be used, which is configured by sandwiching a polymer layer containing suspended particles that can be oriented by the application of a voltage between two electrically insulating films coated with a transparent conductive film on the inside. With such an SPD film, when the power switch is turned on and a voltage is applied between the transparent conductive films, the suspended particles in the polymer layer are oriented, resulting in a state of high visible light transmittance and high transparency. When the power switch is turned off, the suspended particles in the polymer layer are not oriented, resulting in a state of low visible light transmittance and low transparency.

As the SPD film, for example, a commercially available product such as LCF-1103DHA (product name, manufactured by Hitachi Chemical Co., Ltd.) can be used. Note that such commercially available products are supplied in a specified size, and therefore can be cut to the desired size before use. Note that the thickness of the SPD film used in the laminated glass is preferably within the range of the thickness ts of the light control film described above, and from the viewpoints of ease of handling and availability, a thickness of 0.2 to 0.4 mm is preferable.

By using an SPD film, it is possible to electrically switch between high and low visible light transmittance. When the visible light transmittance of the SPD film is low, the contrast ratio between the HUD image and the background can be improved by projecting a HUD image onto the HUD display area where the SPD film is present.

The contrast ratio between the HUD image and the background can also be improved when a polymer dispersed liquid crystal (PDLC) is used as the light control film 3 instead of an SPD film. The PDLC film can be made by mixing a prepolymer, a nematic liquid crystal, and a spacer material in a specific ratio and then placed between two soft transparent conductive films. The operating principle includes the following: When no electric field is applied, the liquid crystal droplets can be randomly distributed in the polymer material with their directors freely oriented.

In such cases, the refractive index of the liquid crystal for ordinary light does not match that of the polymer material, causing a relatively strong scattering effect on the light, resulting in a translucent or opaque "milky" appearance of the PDLC film. Under an electric field, the liquid crystal droplets can align their directors along the direction of the external electric field due to their positive dielectric anisotropy properties. If the refractive index of the liquid crystal for ordinary light matches that of the polymer material, the light can pass through the PDLC film, and the PDLC film will therefore have a transparent appearance. Specifically, the higher the voltage supplied to the PDLC film, the more transparent the PDLC film will be.

As the PDLC film, for example, a commercially available product such as MIYO Film (manufactured by Kyushu Nanotec Optics) can be used. Note that such commercially available products are supplied in a specified size, and are cut to the desired size before use. Note that the thickness of the PDLC film used in the laminated glass is preferably within the range of the thickness ts of the light control film described above, and from the viewpoints of ease of handling and availability, 0.1 to 0.4 mm is preferable.

In addition, the contrast ratio between the HUD image and the background can be improved when any of the following is used as the light control film 3: polymer network liquid crystal (PNLC), guest-host liquid crystal, VA (Vertical Alignment) type liquid crystal, TN (Twisted Nematic) type liquid crystal, photochromic, electrochromic, or electrokinetic.
In addition to the above-mentioned components, the laminated glass of the embodiment may optionally include other layers as long as the effects of the present invention are not impaired.
(Other layers)
In the laminated glass, a dark-colored concealing layer may be provided in a strip shape on a part or the whole of the peripheral portion of the main surface of at least one of the pair of glass sheets constituting the laminated glass, the main surface being in contact with the intermediate adhesive layer, for the purpose of concealing the attachment portion to the frame, wiring conductors, etc. In the laminated glass of the embodiment, such a dark-colored concealing layer may be provided as another layer.

An example of a dark-colored concealing layer is a black ceramic layer. The black ceramic layer can be formed using known materials such as colored ceramic paste. The ink used to form the black ceramic layer is, for example, an ink in which a dark-colored pigment, glass frit, refractory filler, and a resin such as ethyl cellulose are dispersed in a solvent. Usually, the ink is printed in a predetermined pattern on a glass plate, and the plate is pre-baked by drying or ultraviolet irradiation, and then fired at a high temperature to obtain a black ceramic layer that is completely baked on the glass plate. In addition, an intermediate adhesive layer having a dark-colored pigment, a colored film in which a resin film is printed in a dark color, etc. can also be used to form a dark-colored concealing layer.

From the standpoint of design, laminated glass may have a narrow dark-colored concealing layer or may not have a dark-colored concealing layer at all. An example of a laminated glass that does not have a dark-colored concealing layer is door glass for vehicles.

In the laminated glass, when the width of the dark-colored concealing layer is reduced at the periphery or when the dark-colored concealing layer is not provided, the laminated glass of the present invention satisfies the requirements (i-1) to (i-3), and the distance w between the outer periphery of the light control film and the outer periphery of the laminated glass can be reduced without impairing the appearance of the laminated glass and while ensuring the durability of the light control film, which is preferable. When the width of the dark-colored concealing layer is reduced, specifically, when the width of the dark-colored concealing layer is 100 mm or less, further 50 mm or less, and particularly 20 mm or less, the effect of the present invention can be particularly remarkably enjoyed. Within the scope of the present invention, the w of the short side may be relatively small compared to the long side of the polygon in plan view from the viewpoint of design. In this way, the width of the concealing layer on the short side can be reduced.
[Manufacture of laminated glass]
The laminated glass according to the embodiment of the present invention can be manufactured by a commonly used known technique. For example, in the laminated glass 10A, a laminate is prepared in which a light control film 3 is arranged between a pair of intermediate adhesive layers 2A and 2B so as to have a predetermined positional relationship, and this is inserted between a pair of glass plates 1A and 1B to prepare a laminated glass precursor, which is a laminated glass before pressure bonding in which the glass plate 1A, intermediate adhesive layer 2A, light control film 3, intermediate adhesive layer 2B, and glass plate 1B are laminated in this order. In the case of having other layers, the laminated glass precursor is prepared by laminating the glass plate and each layer in the same lamination order as the laminated glass obtained in the same manner.

The laminated glass of the embodiment can be obtained by placing this laminated glass precursor in a vacuum bag such as a rubber bag, connecting this vacuum bag to an exhaust system, and bonding at a temperature of about 70 to 110°C while vacuum suction (degassing) so that the pressure inside the vacuum bag is reduced to a reduced pressure of about -65 to -100 kPa (hereinafter also referred to as "vacuum heat and pressure bonding"). Furthermore, by performing a pressure bonding process (hereinafter also referred to as "pressure heat and pressure bonding") in which heating and pressurization are performed under conditions of 100 to 110°C and a pressure of 0.6 to 1.3 MPa, for example, a laminated glass with superior durability can be obtained.

Pressure-heat bonding is typically performed using an autoclave. By performing pressure-heat bonding after reduced pressure-heat bonding, it is possible to mitigate the reduction in thickness at the edge of the laminated glass obtained by reduced pressure-heat bonding, which is caused by the thickness ts of the light-control film being small in the frame-like region of width w where the light-control film of the laminate is not present. Specifically, the above T2-T1 can be easily set to 0.28 mm or less, more preferably 0.2 mm or less, and even more preferably 0.15 mm or less. This can eliminate residual stress in the laminated glass and suppress the occurrence of defects such as peeling and foaming of the intermediate adhesive layer.

In the present invention, in a laminated glass provided with a light-control film, it is possible to protect the edge of the light-control film without impairing the appearance, and a laminated glass with improved productivity is obtained. The laminated glass of the present invention is preferably used, for example, as a window glass for a vehicle.

The present invention will be described in more detail below with reference to examples. The present invention is not limited to the embodiments and examples described below. Examples 1 to 6, 9 to 22, and 25 to 42 are examples, and Examples 7, 8, 23, and 24 are comparative examples.
[Examples 1 and 2]
(Preparation of laminated glass)
A laminated glass having a configuration similar to that of the laminated glass 10A shown in Figures 1 and 2 was produced as follows. Hereinafter, the components of the evaluation sample corresponding to the components of the laminated glass 10A will be described with the same reference numerals as those in the laminated glass 10A.

Two soda lime glass plates 1A and 1B (manufactured by AGC, commonly known as FL, 2 mm thick, 150 mm x 150 mm square), two saponified EVA intermediate adhesive layers 2A and 2B (manufactured by Tosoh-Nikkemi, Mersen G (product name), 0.4 mm thick, 150 mm x 150 mm square), and one light control film 3 (manufactured by Hitachi Chemical, LCF-1103DHA90 (product name), SPD light control film, 0.35 mm thick, 140 mm x 140 mm square). These were laminated in the following order: one glass plate 1A, one EVA intermediate adhesive layer 2A, SPD light control film 3, the other EVA intermediate adhesive layer 2B, and the other glass plate 1B to obtain a laminate. The distance w between the outer periphery of the SPD light control film 3 and the outer periphery of the laminate was 5 mm on all four sides.

The laminate obtained above was placed in a rubber vacuum pack and degassed (vacuum pressure: -90 kPa), then placed in an oven maintained at 100°C and left for 60 minutes, vacuum heated and pressed, and then removed from the rubber vacuum pack to obtain laminated glass 1A. Laminated glass 1A was pressurized, heated and pressed in an autoclave at 110°C and a pressure of 1.3 MPa for 20 minutes to obtain laminated glass 1B. In laminated glass 1A and laminated glass 1B, the thickness ts of SPD light control film 3, the total thickness ti of intermediate adhesive layers 2A and 2B, and the distance w between the outer periphery of SPD light control film 3 and the outer periphery of the laminated glass are all the same as the values for the above laminate. Laminated glass 1A was taken as Example 1 and laminated glass 1B as Example 2.

For the laminated glass 1A and the laminated glass 1B, the thickness T1 at one point (measurement point E) at the end and the thickness T2 at a position (measurement point I) 50 mm inward from the one point at the end (measurement point E) were measured with a vernier caliper, and the thickness difference = thickness T2 [mm] at a position (measurement point I) 50 mm inward from the end of the laminated glass - thickness T1 [mm] at the end of the laminated glass (measurement point E). In this example, the measurement point E was the center point of one side of the outer periphery of the laminated glass, and the measurement point I was a position 50 mm inward from the measurement point E toward the center of the laminated glass. The results are shown as thickness difference in FIG. 3, with the laminated glass 1A as Example 1 and the laminated glass 1B as Example 2.
<Evaluation>
(exterior)
The appearance of the laminated glass 1A and the laminated glass 1B was visually evaluated according to the following criteria.
◯ (Good): No air remaining or bubbles were observed in the region 3 mm inside from the edge of the laminated glass.
Δ (Fair): Less than 20 ^mm2 of air remaining and bubbles were observed in an area 3 mm inward from the edge of the laminated glass. × (Poor): At least one of air remaining and bubbles of 20 ^mm2 or more was observed in an area 3 mm inward from the edge of the laminated glass.
(Durability evaluation)
The laminated glass 1A and the laminated glass 1B were placed in a thermohygrostat at 60°C and 95%RH for 500 hours. Moisture was allowed to penetrate the intermediate adhesive layer, creating an environment in which peeling due to residual stress is likely to occur, and the presence or absence of peeling was visually evaluated. When peeling of ²⁰ mm2 or more was observed, it was evaluated as ×, when peeling of less than 20 ^mm2 was observed, it was evaluated as △, and when peeling was not observed, it was evaluated as ◯.

The evaluation results are shown in FIG. 3 together with w, ti, ts, whether formula 1 is satisfied (if satisfied, it is marked with "○"; if not, it is marked with "×"), whether formula 2 is satisfied (if satisfied, it is marked with "○"; if not, it is marked with "×"), and the manufacturing method (A: reduced pressure heat bonding only, B: reduced pressure heat bonding + pressure heat bonding).
[Examples 3 to 16]
In Examples 1 and 2, (1) the shape of the SPD light control film 3 was changed to w as shown in Figure 3 while keeping the material the same, (2) the total thickness ti of the intermediate adhesive layers 2A and 2B was changed to that shown in Figure 3 while keeping the material the same, and (3) manufacturing method A or B was selected as shown in Figure 3 to produce laminated glass of Examples 3 to 16, and evaluations were performed in the same manner as above. The measurement results are shown in Figure 3. In Examples 7, 8, 23, and 24, which are comparative examples, air remained, and the appearance evaluation was "x".
[Examples 17 to 32]
In Examples 1 and 2, LCF-1103DHA30 (product name, Hitachi Chemical Co., Ltd., SPD light control film, 0.28 mm thick) was used as the light control film 3 instead of LCF-1103DHA90 (product name, Hitachi Chemical Co., Ltd.), (1) the shape of the light control film 3 was changed to w as shown in Figure 3, (2) the intermediate adhesive layers 2A and 2B were made of the same material but the total thickness ti was changed as shown in Figure 3, and (3) A or B was selected as the manufacturing method as shown in Figure 3 to produce the laminated glasses of Examples 17 to 22, and the same evaluations were performed as above. The measurement results are shown in Figure 3.
[Examples 33 to 42]
In Examples 1 and 2, MIYO film (product name, manufactured by Kyushu Nanotec Optics, PDLC film, 0.12 mm thick) was used as the light control film 3 instead of LCF-1103DHA90 (product name, manufactured by Hitachi Chemical Co., Ltd.), (1) the shape of the light control film 3 was changed to w as shown in Figure 3, (2) the intermediate adhesive layers 2A and 2B were made of the same material but the total thickness ti was changed as shown in Figure 3, and (3) manufacturing method A or B was selected as shown in Figure 3 to produce laminated glass of Examples 23 to 32, and the same evaluation as above was performed. The evaluation results are shown in Figure 3.

FIG. 3 shows that if requirements (i-1) and (i-3) are met and the relationship between w, ti, and ts satisfies formula 1 (requirement (i-2)), that is, if all requirements (i-1) to (i-3) are met, it is possible to protect the edge of the light control film without impairing the appearance, and a laminated glass with improved productivity can be obtained.

The present invention has been described above based on embodiments and examples, but the present invention is not limited to the above embodiments and examples, and various modifications are possible within the scope of the claims.

This application claims priority to basic application No. 2019-038676, filed on March 4, 2019, with the Japan Patent Office, the entire contents of which are incorporated herein by reference.

10A Laminated glass 1A, 1B Glass plates 2A, 2B Intermediate adhesive layer 3 Light control film.

Claims (16)

A pair of glass plates facing each other;
a pair of intermediate adhesive layers located between the pair of glass plates and in contact with the pair of glass plates, respectively;
A laminated glass having a light control film capable of switching visible light transmittance, the light control film being located between the pair of intermediate adhesive layers,
The laminated glass has a substantially polygonal shape in a plan view, and at least one side of the outer periphery of the laminated glass satisfies the following requirements (i-1) to (i-3).
(i-1) The outer periphery of the light control film is located a distance w [mm] inside from the outer periphery of the laminated glass in a plan view,
(i-2) When the thickness of the light control film is ts [mm] and the total thickness of the pair of intermediate adhesive layers is ti [mm],
The w is 5 mm or more and 20 mm or less,
The ts is 0.12 mm or more and 0.35 mm or less ,
The ti is 0.8 mm or more and 1.6 mm or less,
The w, ti, and ts satisfy the following formula 1,
0<w/ti<7/ts Formula 1
(i-3) The pair of intermediate adhesive layers contact each other in a region from the outer periphery of the laminated glass to the outer periphery of the light control film. The laminated glass according to claim 1, wherein at least two sides of the outer periphery of the laminated glass satisfy the requirements (i-1) to (i-3). The laminated glass according to claim 2, which satisfies the requirements (i-1) to (i-3) around the entire outer periphery of the laminated glass. The laminated glass according to any one of claims 1 to 3, wherein an edge of the laminated glass that satisfies the requirements (i-1) to (i-3) in an outer periphery thereof further satisfies the following requirement (i-4):
(i-4) The w, ti, and ts satisfy the following formula 2.
0<w/ti<4.5/ts Formula 2 The laminated glass according to any one of claims 1 to 4, wherein the laminated glass has a substantially quadrilateral shape in a plan view. The laminated glass according to claim 5, wherein the laminated glass is substantially quadrilateral in plan view, and the w is 10 mm or less on at least one side that satisfies the requirements (i-1) to (i-3). The laminated glass according to any one of claims 1 to 6, wherein the material of the intermediate adhesive layer contains at least one selected from the group consisting of polyvinyl butyral resin, ethylene vinyl acetate copolymer resin, polyurethane resin, ionomer resin, and cycloolefin polymer. 8. The laminated glass according to claim 1, wherein the intermediate adhesive layer has a minimum storage modulus of 2.0×10 ⁶ Pa or less in a temperature range of 90 to 120° C., as determined by dynamic viscoelasticity measurement at a measurement frequency of 10 Hz. The laminated glass according to any one of claims 1 to 8, in which T2 - T1 is 0.28 mm or less, where T1 is the total thickness of the laminated glass at the end of the laminated glass and T2 is the total thickness of the laminated glass 50 mm inside from the end. The laminated glass according to any one of claims 1 to 9, which does not have a dark-colored shielding layer on the periphery. The laminated glass according to any one of claims 1 to 10, wherein the light control film is a suspended particle device, a polymer dispersed liquid crystal, a polymer network liquid crystal, a guest-host liquid crystal, a VA type liquid crystal, a TN type liquid crystal, a photochromic, an electrochromic, or an electrokinetic. The laminated glass according to any one of claims 1 to 11 , wherein the light control film has a thickness ts of 0.28 mm or less. The laminated glass according to any one of claims 1 to 12 , wherein a ratio of an area of the light control film to an area of the laminated glass in a plan view is 0.7 or more. The laminated glass according to any one of claims 1 to 13, wherein the laminated glass is attached to a vehicle, and the thickness of the glass plate located on an inner side of the pair of glass plates is thinner than the thickness of the glass plate located on an outer side of the vehicle . The laminated glass according to claim 14 , wherein the glass sheet located on the vehicle interior side contains iron in a composition thereof in an amount of 0.4 mass % or more, calculated as _{Fe2O3 ,} based on a total iron content on an oxide basis. 16. The laminated glass according to claim 14 , wherein the thickness of the intermediate adhesive layer located on the vehicle inner side of the pair of intermediate adhesive layers is thinner than the thickness of the intermediate adhesive layer located on the vehicle outer side.

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