JP7530176B2 - Laminated Film and Laminate - Google Patents

Description

The present invention relates to a laminate film and a laminate.

Surface protection films are used by being attached to adherends such as resin products, metal products, glass products, and semiconductor wafers for optical and building materials, and serve to prevent scratches, breakage, and the inclusion of foreign matter when transporting, storing, and processing these, as well as to act as a support in certain processes. These surface protection films generally include a non-adhesive surface layer and an adhesive layer for bonding to the adherend. The surface layer is usually a layer formed from a polyolefin such as polyethylene or polypropylene, a polyester such as polyethylene terephthalate, or a vinyl polymer such as polyvinyl chloride.

The properties required for such a surface protection film include a suitable adhesive strength to the adherend, no lifting or peeling of the surface protection film from the adherend, no defects such as deformation or chipping of the adherend, and no components of the adhesive layer remaining on the adherend when the film is peeled off for use. In particular, when a laminate in which a surface protection film is attached to an adherend is placed under high temperature conditions, the adherend and the surface protection film are likely to shrink or soften, so the performance required for the surface protection film is even higher than that required for general-purpose laminate films other than surface protection films.

Patent Document 1 discloses a surface protection film obtained by coextrusion molding, in which an adhesive layer is made of a resin composition consisting of a styrene-based elastomer, a tackifier resin, and a polyolefin-based resin.
Patent Document 2 discloses a surface protection film in which a styrene-based elastomer and an olefin-based copolymer are used in the adhesive layer.
Furthermore, Patent Document 3 discloses a surface protection film that uses a propylene-based copolymer in the base layer, thereby making it possible to suppress lifting or peeling of the film even if temperature changes occur during storage or the like.

JP 2012-131978 A JP 2015-034215 A JP 2014-208734 A

In recent years, there has been a shift from cathode ray tube displays to flat panel displays such as liquid crystal displays and plasma displays, and the spread of multi-function mobile phones and mobile information terminals such as smartphones. As the components used in these devices have become more highly functional and high performance, an increasing number of components have large uneven surfaces or have been surface-treated to have uneven surfaces. This inevitably reduces the contact area between these components and the adhesive layer of the surface protection film, making the surface protection film more likely to become partially deformed. If the surface protection film is exposed to high temperatures during transportation, storage, processing, etc. in this state, the deformed parts will try to return to their original state, causing the surface protection film to float off the adherend and become more likely to peel off.

However, while the surface protection films described in Patent Documents 1 and 2 exhibit adequate adhesive strength when bonded at room temperature, it has been found that when the film is bonded to an adherend, particularly a component having a surface shape with large irregularities, it floats or peels off at high temperatures.
Furthermore, it was found that the surface protection film described in Patent Document 3 does not have a sufficient stress relaxation effect, and when subjected to heat treatment after being bonded to an adherend, the laminate formed by bonding the surface protection film to the adherend warps.

The present invention has been made in consideration of the above. The objective of the present invention is to provide a laminate film that exhibits appropriate adhesive strength to an adherend, is resistant to lifting or peeling from the adherend even at high temperatures, can be easily peeled off from the adherend, is resistant to leaving an adhesive layer on the adherend, and can suppress warping of the laminate with the adherend even at high temperatures.

As a result of intensive research by the present inventors to solve the above problems, they found that the above problems can be solved by a specific laminate film, and thus completed the present invention.
A configuration example of the present invention is as follows.

[1] A laminated film comprising a base layer (A) and an adhesive layer (X),
In a tensile test in accordance with JIS K7127 (using a test piece having a thickness of 50 μm, a width of 15 mm, and a length of 100 mm corresponding to test piece type 2), the laminated film has a tensile force of 8 N or less when elongated by 10% at 23° C. and a tensile speed of 200 mm/min, and a tensile modulus of elasticity of less than 1,500 MPa,
The base layer (A) comprises 5 to 100 mass % of a thermoplastic resin (A-1) having a tan δ value (loss tangent) of 0.15 or more at 23°C and a tan δ value of 0.08 or more at 50°C, as measured by dynamic viscoelasticity measurement at a frequency of 1.6 Hz;
and 0 to 95% by mass of a polyolefin (A-2) other than the thermoplastic resin (A-1) (wherein the total of (A-1) and (A-2) is 100% by mass).
Laminated film.

[2] The laminated film according to [1], wherein the thermoplastic resin (A-1) contains a copolymer in which the structural unit (I) derived from 4-methyl-1-pentene is 50 to 96 mol % and the structural unit (II) derived from an α-olefin having 2 to 20 carbon atoms (excluding 4-methyl-1-pentene) is 4 to 50 mol % (the sum of (I) and (II) is 100 mol %).

[3] The laminate film according to [1] or [2], wherein the thermoplastic resin (A-1) satisfies at least one of the following requirements (i) to (iv):
(i) The intrinsic viscosity [η] measured in decalin at 135°C is 0.1 to 5.0 dl/g. (ii) The molecular weight distribution (Mw/Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC), is 1.0 to 3.5. (iii) The melting point measured by differential scanning calorimetry (DSC) is less than 200°C, or no melting point is observed by DSC. (iv) The density is 830 to 860 kg/ ^m3.

[4] The laminate film according to any one of [1] to [3], wherein the polyolefin (A-2) contains a propylene-based polymer.

[5] The adhesive layer (X),
(B) an ethylene-based polymer or an olefin-based polymer mainly composed of a structural unit derived from an α-olefin having 3 or more carbon atoms;
A styrene-based polymer (C), and
(Meth)acrylic polymer (D)
The laminate film according to any one of [1] to [4], which contains one or more polymers selected from the following:

[6] The laminate film according to any one of [1] to [5], which is a protective film.

[7] A laminate film according to any one of [1] to [6],
An adherend having a tensile modulus of 1500 MPa or more when elongated at 23°C and a tensile speed of 200 mm/min in accordance with JIS K7127 (using a test piece having a thickness of 50 μm, a width of 15 mm, and a length of 100 mm corresponding to test piece type 2);
Including,
The adhesive layer (X) in the laminated film is in contact with the adherend,
Laminate.

The laminated film according to the present invention exhibits a suitable adhesive strength to the adherend, is unlikely to lift or peel off from the adherend even at high temperatures, can be easily peeled off from the adherend, and does not leave any components derived from the adhesive layer on the adherend. In addition, by using the laminated film according to the present invention, a laminate of the laminated film and the adherend that is unlikely to warp even at high temperatures can be obtained. Therefore, the laminated film according to the present invention can be suitably used as a surface protection film for optical substrates, building materials, automobile parts, semiconductor wafers, etc., and has extremely high industrial utility value.
Furthermore, the laminated film according to the present invention satisfactorily exhibits the above-mentioned effects even when an adherend having a surface shape with large projections and recesses is used.

Specific embodiments of the present invention will be described in detail below. However, the present invention is not limited to the following embodiments and can be modified as appropriate within the scope of the object of the present invention.
In this specification, the terms "(co)polymer" and "polymer" are used to include homopolymers and copolymers.

<Laminated film>
The laminated film according to the present invention (hereinafter also referred to as "the film") includes a base layer (A) and an adhesive layer (X),
In a tensile test in accordance with JIS K7127 (using a test piece having a thickness of 50 μm, a width of 15 mm, and a length of 100 mm corresponding to test piece type 2), the laminated film has a tensile force of 8 N or less when elongated by 10% at 23° C. and a tensile speed of 200 mm/min, and a tensile modulus of elasticity of less than 1,500 MPa,
The base layer (A) comprises 5 to 100 mass % of a thermoplastic resin (A-1) having a tan δ value (loss tangent) of 0.15 or more at 23° C. and a tan δ value (loss tangent) of 0.08 or more at 50° C., as measured by dynamic viscoelasticity measurement at a frequency of 1.6 Hz;
and 0 to 95% by mass (A-2) of a polyolefin other than the thermoplastic resin (A-1) (wherein the total of (A-1) and (A-2) is 100% by mass).

The tensile strength of the present film is preferably 7.5 N or less, more preferably 7.0 N or less, and preferably 1 N or more.
The tensile modulus of the present film is preferably 1400 MPa or less, more preferably 1200 MPa or less, and preferably 500 MPa or more.
When the tensile strength and tensile modulus of the present film are within the above ranges, a laminate film exhibiting the above-mentioned effects can be easily obtained, and in particular, a laminate of the laminate film and an adherend that is less likely to warp even at high temperatures can be easily obtained.

The present film is not particularly limited as long as it contains at least the base layer (A) and the adhesive layer (X), and may have two or more of these layers, or may have one or more layers other than these layers.

The thickness of the present film is, for example, 4 to 500 μm, preferably 4 to 350 μm, and more preferably 4 to 300 μm.
The thickness of the substrate layer (A) is, for example, 2 to 400 μm, preferably 2 to 300 μm, more preferably 2 to 250 μm, and still more preferably 3 to 200 μm.
The thickness of the adhesive layer (X) is, for example, 2 to 100 μm, preferably 2 to 80 μm, more preferably 2 to 60 μm, and still more preferably 2 to 50 μm.
There is no particular limitation on the thickness of these layers, and they may be appropriately selected depending on the intended use.

By making the thickness of the base layer (A) and the adhesive layer (X) within the above ranges, and in particular by making the thickness of the base layer (A) thicker than the adhesive layer (X), the present film can be easily obtained with a good balance between dimensional stability and mechanical strength at high temperatures. Furthermore, for example, by making the thickness of the base layer (A) in a range equivalent to 2 to 5 times the thickness of the adhesive layer (X), the present film tends to have a tensile strength and tensile modulus within the above ranges.

The uses of the present film are not particularly limited, but examples thereof include surface protection films used for optical substrates, building materials, automobile parts, semiconductor wafers, etc., in order to better exhibit the effects of the present invention.
The present film can also be used as a support when processing an adherend.

<Substrate layer (A)>
The base layer (A) contains 5 to 100 mass % of a thermoplastic resin (A-1) having a tan δ value (loss tangent) of 0.15 or more at 23°C and a tan δ value (loss tangent) of 0.08 or more at 50°C, as measured by dynamic viscoelasticity measurement at a frequency of 1.6 Hz, and 0 to 95 mass % of a polyolefin (A-2) other than the thermoplastic resin (A-1) (wherein the total of the thermoplastic resin (A-1) and the polyolefin (A-2) is 100 mass %).
The base layer (A) is preferably a layer that allows the tensile strength and tensile modulus of the resulting laminate film to fall within the above-mentioned ranges, and is more preferably a layer consisting of only the thermoplastic resin (A-1) and polyolefin (A-2).
The thermoplastic resin (A-1) used in the base layer (A) may be one type or two or more types, and the polyolefin (A-2) that can be used in the base layer (A) may be one type or two or more types.

<Thermoplastic resin (A-1)>
The tan δ value at 23° C. is preferably 0.20 to 3.0, and the tan δ value at 50° C. is preferably 0.10 to 1.0.
By using the thermoplastic resin (A-1) having a tan δ value at 23° C. and 50° C. in the above range, a laminate film having sufficient stress relaxation properties can be obtained. Even when exposed to high temperatures, the film is prevented from lifting or peeling off from the substrate.
When a resin having a tan δ value at 23° C. of less than 0.15 and a tan δ value at 50° C. of less than 0.08 is used, sufficient stress relaxation properties cannot be obtained, and the laminated film and the coating are not easily bonded. When a laminate made of such a material is exposed to high temperatures, the laminate film tends to easily lift or peel off from the adherend.

The thermoplastic resin (A-1) preferably contains an olefin-based polymer mainly composed of a structural unit derived from an α-olefin having 3 or more carbon atoms, and the thermoplastic resin (A-1) preferably is substantially this polymer.
The thermoplastic resin (A-1) may be any resin that satisfies the above-mentioned tan δ value, and the structure thereof may be an isotactic structure, a syndiotactic structure, or an atactic structure.

Preferably, the thermoplastic resin (A-1) is a 4-methyl-1-pentene-propylene copolymer, a 4-methyl-1-pentene-1-butene copolymer, a 4-methyl-1-pentene-propylene-1-butene copolymer, a 4-methyl-1-pentene homopolymer, a propylene homopolymer having a syndiotactic structure, a propylene-ethylene copolymer, a propylene-1-butene copolymer, a propylene-ethylene-1-butene copolymer, or the like.

The thermoplastic resin (A-1) is preferably a 4-methyl-1-pentene copolymer mainly composed of 4-methyl-1-pentene. The 4-methyl-1-pentene copolymer can be obtained by polymerizing 4-methyl-1-pentene and, if necessary, an α-olefin having 2 to 20 carbon atoms (excluding 4-methyl-1-pentene) or other compound using a conventionally known olefin polymerization catalyst, such as a vanadium catalyst, a titanium catalyst, a magnesium-supported titanium catalyst, or a metallocene catalyst described in WO 01/53369, WO 01/27124, JP-A 3-193796, JP-A 02-41303, etc.

Specific examples of the α-olefins having 2 to 20 carbon atoms include ethylene, propylene, 1-butene, 1-hexene, 1-decene, and 1-dodecene, with propylene being particularly preferred.

The thermoplastic resin (A-1) is preferably an olefin copolymer containing 50 mol % or more of structural units derived from 4-methyl-1-pentene, and more preferably a copolymer of 4-methyl-1-pentene and at least one olefin having 2 to 20 carbon atoms, the temperature of which is 5°C or higher when the dynamic viscoelasticity is measured at a frequency of 1.6 Hz.

As the thermoplastic resin (A-1), when the total of the structural unit (I) derived from 4-methyl-1-pentene and the structural unit (II) derived from an olefin having 2 to 20 carbon atoms (excluding 4-methyl-1-pentene) is taken as 100 mol %, the content of the structural unit (I) is preferably 50 to 96 mol %, more preferably 70 to 96 mol %, and the content of the structural unit (II) is preferably 4 to 50 mol %, more preferably 4 to 30 mol %.
When the contents of the structural units (I) and (II) are within the above ranges, the thermoplastic resin tends to have high stress relaxation properties, and it tends to be possible to easily obtain a thermoplastic resin having tan δ values at 23° C. and 50° C. within the above ranges.

The content (mol %) of the structural units is measured by ¹³ C-NMR, and the specific measurement method is as described in the Examples.

The thermoplastic resin (A-1) preferably satisfies at least one of the following requirements (i) to (iv), and more preferably satisfies all of these requirements.

[Requirement (i)]
The intrinsic viscosity [η] of the thermoplastic resin (A-1) measured in decalin at 135° C. is in the range of 0.1 to 5.0 dl/g.
The intrinsic viscosity [η] is preferably 0.5 to 4.0 dl/g, and more preferably 1.0 to 4.0 dl/g.
By using the thermoplastic resin (A-1) having a limiting viscosity [η] within the above range, excellent moldability is achieved when molding the present film. If the limiting viscosity [η] is less than 0.1 dl/g or exceeds 5.0 dl/g, the moldability of the present film may be impaired.
In addition, by using hydrogen when polymerizing the thermoplastic resin (A-1), the molecular weight of the resin can be controlled, and a resin having a molecular weight ranging from low to high can be freely obtained, and therefore the intrinsic viscosity [η] can be adjusted.

[Requirement (ii)]
The molecular weight distribution (Mw/Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) in terms of polystyrene, measured by gel permeation chromatography (GPC) is in the range of 1.0 to 3.5.
The molecular weight distribution (Mw/Mn) is preferably from 1.2 to 3.0, and more preferably from 1.5 to 2.8.
By using a thermoplastic resin (A-1) having a molecular weight distribution (Mw/Mn) within the above range, excellent moldability is achieved when the present film is molded. On the other hand, if the molecular weight distribution (Mw/Mn) exceeds 3.5, the influence of a low molecular weight and low stereoregularity polymer derived from the composition distribution appears, and the moldability of the present film may be impaired.
Details of the measurement conditions and the like are as described in the Examples section below.

The weight average molecular weight (Mw) of the thermoplastic resin (A-1) in terms of polystyrene, measured by gel permeation chromatography (GPC), is preferably 500 to 10,000,000, more preferably 1,000 to 5,000,000, and even more preferably 1,000 to 2,500,000.

[Requirement (iii)]
The melting point of the thermoplastic resin (A-1) measured by a differential scanning calorimeter (DSC) is less than 200° C., or no melting point is observed by DSC.
When the resin has a melting point, the upper limit is preferably 180° C., more preferably 160° C., and further preferably 140° C. The lower limit is not particularly limited, but is usually 130° C.
The melting point varies depending on the stereoregularity of the polymer contained in the thermoplastic resin (A-1) and the amount of the α-olefin. The melting point can be adjusted by controlling the composition to a desired value using the olefin polymerization catalyst.
Details of the measurement conditions and the like are as described in the Examples section below.

[Requirement (iv)]
The density of the thermoplastic resin (A-1) is 830 to 860 kg/ ^m3 .
The density is preferably between 830 and 850 kg/ ^m3 .
By using the thermoplastic resin (A-1) having a density within the above range, the present film having excellent transparency and dimensional stability can be easily obtained.
For example, when the thermoplastic resin (A-1) is a 4-methyl-1-pentene/α-olefin copolymer, the density can be appropriately adjusted by the composition ratio of the α-olefin.
Details of the measurement conditions and the like are as described in the Examples section below.

The content of the thermoplastic resin (A-1) contained in the base layer (A) is 5 to 100% by mass, preferably 20 to 100% by mass, relative to 100% by mass of the total of the thermoplastic resin (A-1) and the polyolefin (A-2), in order to more effectively exert the above-mentioned effects.

<Polyolefin (A-2)>
As the polyolefin (A-2), any conventionally known polyolefin other than the thermoplastic resin (A-1) can be used.
Examples of the polyolefin (A-2) include low-density, medium-density or high-density polyethylene, high-pressure low-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, propylene-ethylene copolymer, propylene-ethylene-1-butene copolymer, propylene-1-butene copolymer, poly-1-butene, 1-butene-ethylene copolymer, 4-methyl-1-pentene homopolymer, 4-methyl-1-pentene-1-decene copolymer, 4-methyl-1-pentene-1-hexadecene-1-octadecene copolymer, 3-methyl-1-butene homopolymer, cyclic olefin copolymer, and chlorinated polyolefin resin. Propylene-based polymers are preferred, and isotactic polypropylene, syndiotactic polypropylene, propylene-ethylene copolymer, propylene-ethylene-1-butene copolymer, and propylene-1-butene copolymer are more preferred, and isotactic polypropylene and syndiotactic polypropylene are even more preferred.

The content of polyolefin (A-2) contained in the base layer (A) is 0 to 95% by mass, preferably 0 to 70% by mass, relative to 100% by mass of the total of the thermoplastic resin (A-1) and polyolefin (A-2), in order to more effectively exert the above-mentioned effects.

When the base layer (A) contains the thermoplastic resin (A-1) and polyolefin (A-2), the film tends to have good dimensional stability without impairing mechanical properties. In particular, when the thermoplastic resin (A-1) is a 4-methyl-1-pentene-propylene copolymer, the polyolefin (A-2) is preferably a propylene-based polymer, because it has excellent compatibility with the copolymer and can easily produce a film that exhibits the above-mentioned effects.

<Adhesive layer (X)>
The adhesive layer (X) is not particularly limited as long as it is a layer that allows the tensile strength and tensile modulus of the resulting film to fall within the above-mentioned ranges. Generally, the adhesive layer (X) is a layer that has tackiness that allows it to be attached to an adherend, and a layer having a material composition similar to that of known adhesive layers used as adhesive layers in conventional surface protection films can be used.
Among these, from the viewpoints of suppressing damage to the adherend due to the occurrence of fisheyes, migration of the adhesive layer components to the adherend, and so-called adhesive residue, it is preferable to contain one or more polymers selected from an ethylene-based polymer or an olefin-based polymer (B) having as its main component a structural unit derived from an α-olefin having 3 or more carbon atoms, a styrene-based polymer (C), and a (meth)acrylic polymer (D).

The ethylene-based polymer in the ethylene-based copolymer or the olefin-based polymer (B) mainly composed of structural units derived from an α-olefin having 3 or more carbon atoms may be a polymer mainly composed of ethylene, and examples of such polymers include low-, medium- or high-density polyethylene, high-pressure low-density polyethylene, and linear low-density polyethylene. Among low-density polyethylenes, linear low-density polyethylene is preferred because it can impart the tackiness required for adhesive effect.

Examples of the ethylene polymer or the olefin polymer in the olefin polymer (B) mainly composed of a structural unit derived from an α-olefin having 3 or more carbon atoms include a propylene homopolymer, a propylene-ethylene copolymer, a propylene-1-butene copolymer, a propylene-ethylene-1-butene copolymer, a 1-butene homopolymer, a 1-butene-ethylene copolymer, a 4-methyl-1-pentene homopolymer, a 4-methyl-1-pentene-propylene copolymer, a 4-methyl-1-pentene-1-butene copolymer, and a 4-methyl-1-pentene-propylene-1-butene copolymer, and preferably a propylene homopolymer, a propylene-ethylene copolymer, or a 4-methyl-1-pentene-propylene copolymer.
By using the 4-methyl-1-pentene·propylene copolymer, it is possible to easily obtain an adhesive layer (X) that has excellent conformability to irregularities and is less likely to leave adhesive residue on the adherend.
Furthermore, by using a propylene-ethylene copolymer, it is possible to easily obtain an adhesive layer (X) having the tackiness required for adhesive effect.

When the adhesive layer (X) contains an ethylene-based polymer or an olefin-based polymer (B) mainly composed of a structural unit derived from an α-olefin having 3 or more carbon atoms, it is preferable that the adhesive layer (X) contains a 4-methyl-1-pentene-propylene copolymer, a propylene-ethylene copolymer, and a propylene homopolymer, a 4-methyl-1-pentene-propylene copolymer and a linear low-density polyethylene, or a propylene-ethylene copolymer and a propylene homopolymer.
Such an adhesive layer (X) is preferred because it provides a good balance between the tackiness required for adhesive effect and the property of being less likely to leave adhesive residue after peeling from the adherend.

The melt flow rate (MFR) of the ethylene polymer or the olefin polymer (B) mainly composed of structural units derived from an α-olefin having 3 or more carbon atoms, measured at 230°C, is preferably 0.1 to 100 g/10 min, more preferably 0.5 to 50 g/10 min.

As the styrene-based polymer (C), a known styrene-based elastomer having a polystyrene phase as a hard segment can be used. Specific examples include styrene-butadiene copolymer (SBR), styrene-isoprene-styrene copolymer (SIS), styrene-butadiene-styrene copolymer (SBS), styrene-ethylene-butadiene-styrene copolymer (SEBS), hydrogenated products thereof, styrene-isobutylene-styrene triblock copolymer (SIBS), styrene-isobutylene diblock copolymer (SIB), etc.

The (meth)acrylic polymer (D) is not particularly limited as long as it is a polymer of a monomer having a (meth)acryloyl group, but examples thereof include a polymer obtained by reacting a copolymer obtained by copolymerizing a monomer having an ethylenic double bond with a copolymerizable monomer having a reactive functional group, with a monomer containing a polymerizable carbon-carbon double bond having a group capable of reacting with the reactive functional group (however, at least one of these monomers is a monomer having a (meth)acryloyl group).

Examples of the monomer having an ethylenic double bond include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; vinyl esters such as vinyl acetate; acrylonitrile; (meth)acrylamide; and styrene.
These may be used alone or in combination of two or more.

Examples of copolymerizable monomers having the reactive functional group include (meth)acrylic acid, maleic acid, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, and N-methylol (meth)acrylamide. These may be used alone or in combination of two or more.

The monomer containing a polymerizable carbon-carbon double bond having a group capable of reacting with the reactive functional group is not particularly limited. For example, examples of combinations of the reactive functional group and a group capable of reacting with the reactive functional group include a carboxyl group and an epoxy group, a carboxyl group and an aziridyl group, and a hydroxyl group and an isocyanate group.
These may be used alone or in combination of two or more.

The adhesive layer (X) may also contain, for the purpose of controlling the adhesive strength, conventionally known additives, such as resin modifiers such as polyester elastomers, tackifiers such as petroleum resins, hydrogenated petroleum resins, chroman-indene resins, rosin derivatives, and terpene resins, known release agents such as polyolefin waxes, silicone waxes, and antiblocking agents such as silica and talc, antistatic agents, conductive agents, weather stabilizers, crystal nucleating agents, and antioxidants, within the scope of the present invention.

<Surface layer (Z)>
In consideration of releasability, rigidity, dimensional stability, handleability, etc., the present film may be provided with at least one surface layer (Z) on the side of the base layer (A) opposite to the adhesive layer (X).

Examples of the surface layer (Z) include layers containing known resins such as polyolefins, polyesters, polyamides, polystyrenes, silicone resins, fluororesins, and vinyl polymers such as polyvinyl chloride.
Among these, when producing the present film in which the surface layer (Z) and the base layer (A) are laminated, a layer made of a polyolefin is preferred as the surface layer (Z) from the viewpoint of excellent interlayer adhesion between the surface layer (Z) and the base layer (A), etc.

Specific examples of the polyolefin include propylene homopolymers, copolymers of propylene and at least one α-olefin having a carbon number other than 3, high-pressure low-density polyethylene, linear low-density polyethylene, high-density polyethylene, and 4-methyl-1-pentene copolymers. Among these, propylene-based polymers such as propylene homopolymers and copolymers of propylene and at least one α-olefin having a carbon number other than 3 are more preferred, as they are less likely to cause fish eyes (crosslinked gels), and from the standpoint of releasability, etc., block copolymers of propylene and at least one α-olefin having a carbon number other than 3 are even more preferred.

The surface layer (Z) may contain one type of resin or two or more types of resin, and may contain, as necessary, conventionally known additives, such as polyolefin wax, silicone wax, antiblocking agents such as silica and talc, known release agents, antistatic agents, conductive agents, weather stabilizers, crystal nucleating agents, and antioxidants, to the extent that the characteristics of the present invention are not impaired.

The thickness of the surface layer (Z) is not particularly limited and may be appropriately selected depending on the desired application, but is, for example, 1 to 100 μm, preferably 5 to 30 μm.

<Method of manufacturing laminated film>
The method for producing the present film is not particularly limited, and the film can be produced by a normal molding method such as coextrusion molding or extrusion lamination using the polymers constituting each layer. Other examples include a method of extrusion coating a layer previously obtained by T-die extrusion molding, inflation film molding, or the like, and a method of laminating films to be each layer by dry lamination, or the like.
Among these, the T-die coextrusion molding method is preferred because it allows the present film to be produced easily and maintains high quality.

<Laminate>
The present film is usually used as a laminate in which it is laminated with an adherend. That is, in this specification, a laminate of the present film and an adherend is referred to as a laminate.
In this laminate, the present film is preferably laminated so that the adhesive layer (X) side faces the adherend, and it is more preferable that the present film is laminated so that the adhesive layer (X) and the adherend are in contact with each other.

The adherend is not particularly limited, but is preferably an adherend having a tensile modulus of 1500 MPa or more, more preferably 1800 to 4500 MPa, when elongated at 23° C. and a tensile speed of 200 mm/min in accordance with JIS K7127 (using a test piece having a thickness of 50 μm, a width of 15 mm, and a length of 100 mm corresponding to test piece type 2).
An adherend having a tensile modulus within the above range is characterized by being hard at room temperature and not easily shrinking.

Examples of the substrate include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), polyamide (PA), cyclic olefin copolymers (COP, COC), poly(meth)acrylate, silicon wafers, glass, etc.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The physical properties of the raw materials used in the examples and comparative examples were measured as follows.

<Melt flow rate (MFR)>
The measurement was performed in accordance with ASTM D1238 at a load of 2.16 kg and a temperature of 230°C or 190°C.

<Melting Point>
According to JIS K7121, a differential scanning calorimeter (DSC) was used, and the highest temperature corresponding to the apex of the melting peak measured at a heating rate of 10° C. per minute was taken as the melting point.

<Content of structural units>
The content of each structural unit in the polymer was measured by ¹³ C-NMR under the following conditions:
Measurement device: Nuclear magnetic resonance device (ECP500 type, manufactured by JEOL Ltd.)
Observed nucleus: ^13C (125MHz)
Sequence: Single pulse proton decoupling Pulse width: 4.7 μs (45° pulse)
Repeat time: 5.5 seconds; Accumulation count: 10,000 or more; Solvent: orthodichlorobenzene/deuterated benzene (volume ratio: 80/20) mixed solvent; Sample concentration: 55 mg/0.6 mL
・Measurement temperature: 120℃
Chemical shift reference value: 27.50 ppm

<Measurement of tan δ value (loss tangent)>
A predetermined amount of the following raw material resin was filled into a SUS mold, and a hydraulic hot press machine (PEWR-30, manufactured by Kansai Roll Co., Ltd., pressure: 29.4 kN) with a heating plate set to 200°C was used to preheat for 7 minutes and pressurize for 2 minutes at a gauge pressure of 10 MPa. The mixture was then transferred to a cooling plate set to 20°C, compressed at a gauge pressure of 10 MPa, and cooled for 3 minutes to obtain a press sheet for measurement having a thickness of 2.0 mm.

Using an Anton Paar rheometer MCR301, the temperature dispersion of dynamic viscoelasticity was measured at temperatures from -40 to 120°C under the conditions of torsion mode, frequency of 1.6 Hz, strain setting of 0.1%, and heating rate of 2°C/min. The temperature at which tan δ (loss tangent) due to the glass transition temperature reaches its maximum value (temperature of maximum tan δ), the tan δ value at that time (maximum tan δ value), the tan δ value at 23°C, and the tan δ value at 50°C were measured.

<Intrinsic viscosity [η]>
The intrinsic viscosity [η] was measured at 135° C. using decalin as a solvent.
Specifically, about 20 mg of the raw resin below was collected and dissolved in 15 ml of decalin, and the resulting decalin solution was placed in an oil bath heated to 135 ° C. to measure the specific viscosity ηsp. After diluting the decalin solution by adding 5 ml of decalin solvent, the specific viscosity ηsp was measured in the same manner. This dilution operation was repeated two more times, and the value of ηsp / C when the concentration (C) was extrapolated to zero was calculated as the limiting viscosity (see the formula below).
[η]=lim(ηsp/C) (C→0)

<Weight average molecular weight (Mw), number average molecular weight (Mn), molecular weight distribution (Mw/Mn)>
Mn and Mw were measured by gel permeation chromatography (GPC).
Specifically, a Waters ALC/GPC150-Cplus type (integrated with a differential refractometer detector) was used as the liquid chromatograph, and two Tosoh GMH6-HT and one GMH6-HTL were used as the separation columns. Two columns were connected in series, and the mobile phase medium was o-dichlorobenzene and the antioxidant was 0.025% by mass of BHT (manufactured by Takeda Pharmaceutical Co., Ltd.). The mobile phase medium was fed at a rate of 1.0 ml/min. The sample concentration was 15 mg/10 ml, the sample injection volume was 500 microliters, and a differential refractometer was used as a detector. In the following, standard polystyrene manufactured by Tosoh Corporation was used.

The weight average molecular weight (Mw), number average molecular weight (Mn) and molecular weight distribution (Mw/Mn value) were calculated by creating a calibration curve using a standard polystyrene sample and analyzing the obtained chromatogram by a known method. The measurement time per sample was 60 minutes.

<Density>
The density was measured in accordance with JIS K7112 (density gradient tube method).

[Synthesis of Thermoplastic Resin (A-1)]
The thermoplastic resin (A-1) was synthesized by the following method.

<Synthesis of Thermoplastic Resin (A-1-1)>
A 1.5-liter SUS autoclave equipped with a stirring blade and thoroughly purged with nitrogen was charged with 300 ml of normal hexane (dried over activated alumina in a dry nitrogen atmosphere) and 450 ml of 4-methyl-1-pentene at 23° C. 0.75 ml of a 1.0 mmol/ml toluene solution of triisobutylaluminum (TIBAL) was charged into the autoclave and stirred.

Next, the autoclave was heated to an internal temperature of 60°C and pressurized with propylene to a total pressure of 0.40 MPa (gauge pressure). Next, 0.34 ml of a toluene solution containing 1 mmol of methylaluminoxane (calculated as Al) and 0.01 mmol of diphenylmethylene(1-ethyl-3-t-butyl-cyclopentadienyl)(2,7-di-t-butyl-fluorenyl)zirconium dichloride, which had been prepared in advance, was pressed into the autoclave with nitrogen to initiate polymerization. During the polymerization reaction, the temperature was adjusted so that the internal temperature of the autoclave was 60°C. 60 minutes after the start of polymerization, 5 ml of methanol was pressed into the autoclave with nitrogen to terminate the polymerization, and the autoclave was depressurized to atmospheric pressure. Next, acetone was poured into the reaction solution while stirring.

The resulting powdered polymer containing the solvent was dried at 100°C under reduced pressure for 12 hours. The resulting thermoplastic resin (A-1-1) weighed 36.9 g, and the 4-methyl-1-pentene content in the resin was 73 mol %, and the propylene content was 27 mol %. When measured by DSC, no melting point was observed.

<Synthesis of Thermoplastic Resin (A-1-2)>
A 1.5-liter SUS autoclave equipped with a stirring blade and thoroughly purged with nitrogen was charged with 300 ml of normal hexane (dried over activated alumina in a dry nitrogen atmosphere) and 450 ml of 4-methyl-1-pentene at 23° C. 0.75 ml of a 1.0 mmol/ml toluene solution of triisobutylaluminum (TIBAL) was added to this autoclave and stirred.

Next, the autoclave was heated to an internal temperature of 60°C and pressurized with propylene to a total pressure of 0.19 MPa (gauge pressure). Next, 0.34 ml of a toluene solution containing 1 mmol of methylaluminoxane (calculated as Al) and 0.01 mmol of diphenylmethylene(1-ethyl-3-t-butyl-cyclopentadienyl)(2,7-di-t-butyl-fluorenyl)zirconium dichloride, which had been prepared in advance, was pressed into the autoclave with nitrogen to initiate polymerization. During the polymerization reaction, the temperature was adjusted so that the internal temperature of the autoclave was 60°C. 60 minutes after the start of polymerization, 5 ml of methanol was pressed into the autoclave with nitrogen to terminate the polymerization, and the autoclave was depressurized to atmospheric pressure. Next, acetone was poured into the reaction solution while stirring.

The resulting powdered polymer containing the solvent was dried at 100°C under reduced pressure for 12 hours. The resulting thermoplastic resin (A-1-2) weighed 44.0 g, and the 4-methyl-1-pentene content in the resin was 84 mol%, and the propylene content was 16 mol%. When measured by DSC, the melting point was 131°C.

The raw materials used in the following examples and comparative examples are as follows:

<Raw material for surface layer (Z): PP-1>
Block polypropylene (Prime Polymer Co., Ltd., F707W, MFR (230°C): 6.0 g/10 min, melting point: 160°C)

<Raw material for substrate layer (A): A-1-1>
4-methyl-1-pentene-propylene copolymer; MFR (230°C): 10 g/10 min; Melting point: not observed; Structural units derived from 4-methyl-1-pentene: 73 mol%
Propylene-derived structural units: 27 mol%
・Dynamic viscoelasticity measurement at a frequency of 1.6 Hz at 23 ° C. tan δ value: 0.88
Maximum tan δ temperature in dynamic viscoelasticity measurement at a frequency of 1.6 Hz: 31° C.
Maximum tan δ value in dynamic viscoelasticity measurement at a frequency of 1.6 Hz: 2.80
・Dynamic viscoelasticity measurement at 50 ° C. at a frequency of 1.6 Hz: tan δ value of 0.57
・Intrinsic viscosity [η]: 1.5 dl/g
・Weight average molecular weight (Mw): 308,000
・Number average molecular weight (Mn): 149,000
・Molecular weight distribution (Mw/Mn): 2.1
・Density: 840kg/ ^m3

<Raw material for substrate layer (A): A-1-2>
4-methyl-1-pentene/propylene copolymer; MFR (230°C): 10g/10min; Melting point: 131°C
Structural units derived from 4-methyl-1-pentene: 84 mol%
Propylene-derived structural units: 16 mol%
・Dynamic viscoelasticity measurement at a frequency of 1.6 Hz at 23 ° C. tan δ value: 0.29
Maximum tan δ temperature in dynamic viscoelasticity measurement at a frequency of 1.6 Hz: 43° C.
Maximum tan δ value in dynamic viscoelasticity measurement at a frequency of 1.6 Hz: 2.30
・Dynamic viscoelasticity measurement at 50 ° C. at a frequency of 1.6 Hz: tan δ value of 0.91
・Intrinsic viscosity [η]: 1.4 dl/g
・Weight average molecular weight (Mw): 297,000
・Number average molecular weight (Mn): 143,000
・Molecular weight distribution (Mw/Mn): 2.1
・Density: 838kg/ ^m3

<Raw material for substrate layer (A): A-2>
Homopolypropylene (manufactured by Prime Polymer Co., Ltd., F107BV, MFR (230° C.): 7.0 g/10 min, melting point: 160° C.), corresponding to the polyolefin (A-2)

<Raw material for adhesive layer (X): X-1>
The same copolymer as A-1-2

<Raw material for adhesive layer (X): X-2>
Linear low-density polyethylene (Prime Polymer Co., Ltd., Evolue SP0540, MFR (190° C.): 3.8 g/10 min, melting point: 98° C., density: 903 kg/m ³ )

<Raw material for adhesive layer (X): X-3>
Propylene-ethylene copolymer (produced with metallocene catalyst, melting point: 115°C, MFR (230°C): 7g/10min)

<Raw material for adhesive layer (X): X-4>
The same polymer as A-2

[Example 1]
A three-type three-layer T-die co-extrusion molding machine capable of laminating the surface layer (Z), the base layer (A) and the adhesive layer (X) in this order (extruder aperture diameter Φ40 mm for the base layer, extruder aperture diameter Φ25 mm for the surface layer and the adhesive layer, T-die width 400 mm, T-die includes a feed block mechanism, a cast roll and a take-up roll process) was used to form the surface layer (Z), block polypropylene (PP-1) and 50% by mass of 4-methyl-1-pentene-propylene copolymer (A-1-1) and 50% by mass of 1-methyl-1-pentene-propylene copolymer (A-1-2) as the base layer (A). % homopolypropylene (A-2), and 20% by mass of 4-methyl-1-pentene-propylene copolymer (X-1), 60% by mass of propylene-ethylene copolymer (X-3), and 20% by mass of homopolypropylene (X-4) were used as the adhesive layer (X). The surface layer (Z) was adjusted to 10 μm, the base layer (A) to 30 μm, and the adhesive layer (X) to 10 μm. Film formation was performed at a cylinder setting temperature of 200 to 240° C., and a laminated film (total thickness 50 μm) in which all three layers were laminated was obtained.

[Examples 2 to 4 and Comparative Examples 1 to 2]
A laminated film was obtained in the same manner as in Example 1, except that the types and amounts of resins constituting each layer were changed as shown in Table 1.

The laminated film obtained above was used to carry out the evaluations described below. The measurement results are shown in Table 1.

<Tensile test>
A test piece having a shape (width 15 mm, length 100 mm) corresponding to the test piece type 2 of JIS K7127 was prepared from the obtained laminated film, and a tensile test was carried out in accordance with JIS K7127. Specifically, the tensile force and tensile modulus when the test piece was elongated by 10% were measured using an autograph precision universal testing machine AG-X-P (test temperature: 23°C, tensile speed: 200 mm/min, chuck distance: 70 mm) manufactured by Shimadzu Corporation.

<Measurement of tan δ value (loss tangent)>
Using a rheometer RSA-III manufactured by TA Instruments, the temperature dispersion of solid viscoelasticity was measured at temperatures of -40 to 130°C under the conditions of a tensile mode, a frequency of 1.6 Hz, and a heating rate of 2°C/min, and the tan δ value at 23°C of the obtained laminated film was calculated.

<Maximum adhesive strength to acrylic plate>
A laminated film was attached to an acrylic plate (Acrylite L manufactured by Mitsubishi Chemical Corporation, thickness 10 mm) having a width of 50 mm and a length of 125 mm, so that the adhesive layer (X) of the obtained laminated film was in contact with the acrylic plate, using a 2 kg rubber roller in accordance with JIS Z0237. Next, under conditions of a temperature of 23°C and a humidity of 50% RH, the peel force when the laminated film was peeled off (180° peeled off) at a test speed of 300 mm/min using a universal material testing machine manufactured by Intesco Corporation was measured, and the peel strength per 50 mm width was taken as the maximum adhesive strength (N).
When sticking was observed, the maximum sticking value was recorded as the maximum adhesive strength (N) per 50 mm width.

<Measurement of tensile stress>
A test piece 15 mm wide and 100 mm long was prepared from the laminated film, and using a tensile tester (Autograph Precision Universal Tester AG-X-P manufactured by Shimadzu Corporation), the test piece was stretched by 10% and the profile of the change in tensile stress over time when the test piece was held in this state was measured under the conditions of a test temperature of 23°C or 120°C, a test speed of 200 mm/min, and a chuck distance of 70 mm. The maximum tensile stress after stretching and the tensile stress after holding for 60 seconds were determined. The relaxation rate was calculated based on the following formula.
Relaxation rate (%)=[(maximum tensile stress value−tensile stress value after 60 seconds of holding)/(maximum tensile stress value)]×100

<Evaluation of lifting/peeling under high temperature>
As the adherend, a PET film (polyester film manufactured by PANAC Co., Ltd.) with dimensions of 10 cm x 10 cm and thickness of 100 μm was used, and a laminate film with dimensions of 10 cm x 10 cm was attached to the adherend so that the adhesive layer (X) was in contact with the adherend to form a laminate, which was then kept in an oven at 120° C. for 30 minutes. Thereafter, the laminate was removed from the oven, and the laminate film was visually checked for lifting or peeling from the adherend in the obtained laminate, and the laminate film was peeled off from the adherend to observe the adhesive residue (residual adhesive layer components) on the adherend.
The following cases were rated as "good": there was no peeling of the laminate film from the adherend, there was a portion of the laminate that was floating from the adherend but the distance between the adherend and the laminate film at that portion was less than 1 cm, and there was no adhesive residue on the adherend.
The case where the laminate film peeled off from the adherend, where there was a portion of the laminate floating from the adherend with a distance of 1 cm or more between the adherend and the laminate film, or where there was adhesive residue on the adherend was rated as ×.
The PET film had a tensile modulus of 3,900 MPa when stretched at a temperature of 23° C. and a tensile speed of 200 mm/min in accordance with JIS K7127 (using a test piece having a thickness of 50 μm, a width of 15 mm, and a length of 100 mm corresponding to test piece type 2).

<Warping of Laminate>
As the adherend, a PET film (polyester film manufactured by PANAC Co., Ltd.) having dimensions of 10 cm x 10 cm and a thickness of 100 μm was used, and a laminate having dimensions of 10 cm x 10 cm was attached to the adherend so that the adhesive layer (X) was in contact with the adherend to form a laminate. The laminate was then left to stand in a thermo-hygrostat at a temperature of 23° C. and a humidity of 80% RH for 24 hours, and then left to stand in an oven set at 120° C. for 30 minutes. The laminate was removed from the oven and allowed to cool naturally to room temperature, and then placed on a horizontal surface so that the laminate film was on the upper side.
The four corners of the laminate were curled to varying degrees. The height of the curled corners of the laminate from the horizontal plane was measured, and the average height (hereinafter also referred to as "curl amount") was calculated from these measurement results, and the warpage of the laminate was evaluated according to the following criteria. In addition, when the laminate was curled one or more times, it was judged as C.
A: Curl amount is less than 15 mm. B: Curl amount is 15 mm or more and less than 30 mm. C: Curl amount is 30 mm or more, or the laminate is curled up more than once, making it difficult to calculate the curl amount.

Claims (4)

A laminated film comprising a base layer (A) and an adhesive layer (X),
the base layer (A) includes at least one surface layer (Z) made of a propylene-based polymer on the opposite side to the adhesive layer (X),
the laminated film has a tensile force of 8 N or less when elongated by 10% at 23° C. and a tensile speed of 200 mm/min in a tensile test in accordance with JIS K7127 (using a test piece having a width of 15 mm and a length of 100 mm corresponding to test piece type 2), and a tensile modulus of elasticity of less than 1,500 MPa;
The base layer (A) comprises 5 to 100 mass % of a thermoplastic resin (A-1) having a tan δ value (loss tangent) of 0.15 or more at 23°C and a tan δ value of 0.08 or more at 50°C, as measured by dynamic viscoelasticity measurement at a frequency of 1.6 Hz;
and 0 to 95% by mass of a polyolefin (A-2) other than the thermoplastic resin (A-1) (wherein the total of (A-1) and (A-2) is 100% by mass),
the thermoplastic resin (A-1) comprises a copolymer in which the structural unit (I) derived from 4-methyl-1-pentene is 50 to 96 mol % and the structural unit (II) derived from an α-olefin having 2 to 20 carbon atoms (excluding 4-methyl-1-pentene) is 4 to 50 mol % (the total of (I) and (II) is 100 mol %),
The polyolefin (A-2) contains a propylene-based polymer,
The adhesive layer (X) contains a 4-methyl-1-pentene-propylene copolymer, a propylene-ethylene copolymer, and a propylene homopolymer, or contains a 4-methyl-1-pentene-propylene copolymer and a linear low-density polyethylene .
Laminated film. The laminate film according to claim 1, wherein the thermoplastic resin (A-1) satisfies at least one of the following requirements (i) to (iv):
(i) The intrinsic viscosity [η] measured in decalin at 135°C is 0.1 to 5.0 dl/g. (ii) The molecular weight distribution (Mw/Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC), is 1.0 to 3.5. (iii) The melting point measured by differential scanning calorimetry (DSC) is less than 200°C, or no melting point is observed by DSC. (iv) The density is 830 to 860 kg/ ^m3. The laminate film according to claim 1 or 2 , which is a protective film. The laminated film according to any one of claims 1 to 3 ,
An adherend having a tensile modulus of 1500 MPa or more when elongated at 23°C and a tensile speed of 200 mm/min in accordance with JIS K7127 (using a test piece having a width of 15 mm and a length of 100 mm corresponding to test piece type 2);
Including,
The adhesive layer (X) in the laminated film is in contact with the adherend,
Laminate.