Composite film, laminate, molded article, and method for manufacturing laminate

Abstract

The objective is to provide a composite film that can suppress or reduce peeling and tearing of protective films (specifically, protective films for composite films) when press-forming laminates (specifically, laminates including metal plates and composite films laminated to metal plates). The objective is also to provide laminates and molded products obtained by press-forming laminates. [Solution] The present invention relates to a composite film 7 including a paint substitute film 8 and a protective film 9. mt (i.e., F5 of the thermoplastic resin film 81 in the MD direction) / S mp (That is, the F5 of the protective film 9 in the MD direction) is 5.0 to 10.0. tt (i.e., F5 of the thermoplastic resin film 81 in the TD direction) / S tp (That is, the F5 of the protective film 9 in the TD direction) is between 5.0 and 10.0.

Description

Technical Field

[0001] The present invention relates to a composite film, a laminate, a molded product, and a method for producing a laminate.

Background Art

[0002] Automobile exterior parts, such as door panels, front fenders, roofs, back doors, hoods, etc., are painted. Spraying paint onto a metal plate for painting, that is, spray painting, is generally performed.

[0003] However, since the paint used in spray painting contains volatile organic compounds (VOCs), spray painting has a large environmental impact. Moreover, since spray painting is performed repeatedly, a large space is required to perform spray painting.

[0004] Instead of painting a metal plate, a method of laminating a paint substitute film on the metal plate (hereinafter sometimes referred to as "laminating") has been proposed (see Patent Document 1). According to this, it is possible to omit spray painting.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] A composite film, including a paint substitute film and a protective film attached to the paint substitute film, may be heat-pressed onto a metal plate and then pressed. In other words, a laminate containing a metal plate and a composite film laminated to the metal plate may be pressed. During this process, the protective film may peel off or tear. If the protective film peels off or tears during the pressing process, the appearance of the molded product obtained by the pressing process may be degraded.

[0007] The present invention aims to provide a composite film that can suppress or reduce peeling and tearing of the protective film when a laminate, specifically a laminate including a metal plate and a composite film laminated on the metal plate, is press-formed. The present invention also aims to provide a laminate and a method for manufacturing the same. The present invention also aims to provide a molded product obtained by press-forming a laminate. [Means for solving the problem]

[0008] To solve this problem, the present invention comprises the configuration described in [1] below. [1] Paint substitute film, A composite film including a protective film, The aforementioned paint substitute film includes a thermoplastic resin film, a coloring layer, and a surface protective layer. At least the thermoplastic resin film, the colored layer, the surface protective layer, and the protective film are stacked in this order. The aforementioned surface protective layer has curability, S mt / S mp The range is 5.0 to 10.0, and S mt This is the 5% strain tensile stress of the thermoplastic resin film in the MD direction, and S mp This is the 5% strain tensile stress of the protective film in the MD direction, S tt / S tp The range is 5.0 to 10.0, and S tt This is the 5% strain tensile stress of the thermoplastic resin film in the TD direction, and Stp is the 5% tensile stress of the protective film in the TD direction, Composite film. Here, the MD direction in [1] means the MD direction of the composite film. The TD direction in [1] means the TD direction of the composite film.

[0009] According to [1], since the coating substitute film includes a colored layer, the metal plate can be decorated or protected with the coating substitute film.

[0010] Moreover, since the surface protective layer of the coating substitute film has curability, the surface protective layer can follow the deformation of the metal plate when the laminate (that is, the laminate including the metal plate and the composite film laminated on the metal plate) is press-worked. In addition, the surface of the colored layer can be effectively protected by curing the surface protective layer.

[0011] Furthermore, since the composite film includes a protective film, the coating substitute film can be protected by the protective film.

[0012] Furthermore, S mt / S mp is 5.0 or more, so peeling of the protective film during press-working can be suppressed or reduced. This will be explained. When the laminate (that is, the laminate including the metal plate and the composite film laminated on the metal plate) is press-worked, a force (as an example, a force that pulls the laminate along the main surface direction of the laminate. Needless to say, other forces may act depending on the part.) acts on the laminate. This force (that is, the force acting on the laminate during press-working) tends to act on the metal plate, the coating substitute film, and the protective film in this order. Here, since the surface protective layer of the coating substitute film has curability, that is, the surface protective layer is uncured, the stress generated in the surface protective layer by this force is not large. As a result, among the forces acting on the laminate during press-working, the force acting on the protective film is moderate. Assuming that the 5% tensile stress (S mp ) of the protective film in the MD direction is that of the thermoplastic resin film in the MD direction (Smt If the ratio is excessively large in relation to the material, the protective film will not be able to stretch in the same way as the thermoplastic resin film when the laminate is pressed, and as a result the protective film will peel off. [1] According to S mt / S mp It is 5.0 or higher, that is, S mp S mt Because it is not excessively large in relation to the other components, the protective film can be stretched in the same way as the thermoplastic resin film when the laminate is pressed, and therefore peeling of the protective film can be suppressed or reduced. Furthermore, S tt / S tp Since the value is 5.0 or higher, peeling of the protective film during press processing can be further suppressed or reduced.

[0013] In addition to this, S mt / S mp The value is 10.0 or less, i.e., the 5% strain tensile stress (S) of the protective film in the MD direction. mp ) is that of the thermoplastic resin film in the MD direction (S mt Because it is not excessively small in relation to (), it is possible to prevent or reduce excessive stress concentration in the protective film when the laminate is press-formed, and therefore it is possible to suppress or reduce tearing of the protective film.

[0014] Furthermore, S tt / S tp Since the value is 10.0 or less, it is possible to further prevent or reduce excessive stress concentration in the protective film when the laminate is press-formed, and therefore further suppress or reduce tearing of the protective film.

[0015] The present invention is preferably configured as described in [2] and later. [2] The composite film according to [1], wherein the thermoplastic resin film is a polyethylene terephthalate film. [3] The composite film according to [1] or [2], wherein the protective film is a polyethylene film. [4] The composite film according to any one of [1] to [3], wherein the surface protective layer comprises at least one of a thermosetting resin and a photocurable resin. [5] Further including an adhesive layer, A composite film according to any one of [1] to [4], wherein at least the thermoplastic resin film, the adhesive layer, the coloring layer, the surface protective layer, and the protective film are stacked in this order. [6] The composite film according to any one of [1] to [5], wherein the thermoplastic resin film is a biaxially oriented polyethylene terephthalate film. [7] The composite film according to [6], comprising the biaxially oriented polyethylene terephthalate film and isophthalic acid copolymerized polyethylene terephthalate. [8] The composite film according to [6] or [7], wherein the biaxially oriented polyethylene terephthalate film comprises polybutylene terephthalate. [9] The composite film according to any one of [1] to [8], wherein the thickness of the thermoplastic resin film is 10 μm or more or 15 μm or more.

[10] The composite film according to any one of [1] to [9], wherein the thickness of the thermoplastic resin film is 20 μm or more or 30 μm or more.

[11] The composite film according to any one of [1] to

[10] , wherein the thickness of the thermoplastic resin film is 200 μm or less or 150 μm or less.

[12] The composite film according to any one of [1] to

[11] , wherein the thickness of the thermoplastic resin film is 100 μm or less or 75 μm or less.

[13] The composite film according to any one of [1] to

[12] , wherein the thermoplastic resin film comprises a first layer and a second layer.

[14] The first layer is located closer to the colored layer than the second layer, The melting point of the first layer is higher than the melting point of the second layer.

[13] The composite film described above.

[15] The composite film according to

[13] or

[14] , wherein the second layer comprises copolymerized polyethylene terephthalate, preferably polyethylene terephthalate copolymerized with at least isophthalic acid.

[16] The composite film according to any one of [1] to

[15] , wherein the thickness of the surface protective layer is 5 μm or more or 10 μm or more.

[17] The composite film according to any one of [1] to

[16] , wherein the thickness of the surface protective layer is 80 μm or less or 60 μm or less.

[18] The composite film according to any one of [1] to

[17] , wherein the protective film is provided on the surface protective layer.

[19] The composite film according to any one of [1] to

[18] , wherein the thickness of the protective film is 10 μm or more or 25 μm or more.

[20] The composite film according to any one of [1] to

[19] , wherein the thickness of the protective film is 35 μm or more or 38 μm or more. [twenty one] The composite film according to any one of [1] to

[20] , wherein the thickness of the protective film is 80 μm or less or 70 μm or less. [twenty two] The composite film according to any one of [1] to

[21] , wherein the protective film is a polyethylene film manufactured by the inflation method. [twenty three] The composite film according to any one of [1] to

[22] , wherein the protective film comprises high-pressure low-density polyethylene (LDPE). [twenty four] The composite film according to

[23] , wherein the protective film further comprises linear low-density polyethylene (LLDPE). [twenty five] The composite film according to any one of [1] to

[24] , wherein the colored layer comprises a coloring agent and a resin.

[26] S mt A composite film as described in any of [1] to

[25] , wherein the pressure is 50 MPa or higher or 60 MPa or higher.

[27] S mt A composite film as described in any of [1] to

[26] , wherein the pressure is 150 MPa or less or 130 MPa or less.

[28] S tt A composite film as described in any of [1] to

[27] , wherein the pressure is 50 MPa or higher or 60 MPa or higher.

[29] S tt A composite film as described in any of [1] to

[28] , wherein the pressure is 150 MPa or less or 130 MPa or less.

[30] A metal plate and The composite film described in any of [1] to

[29] is laminated on the metal plate, Laminated structure.

[31]

[30] A molded product obtained by press-forming the laminate described above.

[32] The process of heating the metal plate, The process includes pressing a composite film according to any one of [1] to

[29] onto the heated metal plate, A method for manufacturing laminates. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a composite film that can suppress or reduce peeling and tearing of the protective film when a laminate, specifically a laminate including a metal plate and a composite film laminated on the metal plate, is press-formed. According to the present invention, it is also possible to provide a laminate and a method for manufacturing the same. According to the present invention, it is also possible to provide a molded product obtained by press-forming a laminate. [Brief explanation of the drawing]

[0017] [Figure 1] This is a schematic cross-sectional view of the composite film in this embodiment. [Figure 2] This is a schematic cross-sectional view of the laminate in this embodiment. [Modes for carrying out the invention]

[0018] Embodiments of the present invention will be described in detail below.

[0019] <1. Composite film> As shown in Figure 1, the composite film 7 includes a paint substitute film 8 and a protective film 9. In the composite film 7, the protective film 9 is provided on top of the paint substitute film 8.

[0020] The MD direction of the composite film 7 is synonymous with the MD direction of the thermoplastic resin film 81 in the composite film 7. That is, the MD direction of the composite film 7 coincides with the MD direction of the thermoplastic resin film 81 in the composite film 7. The MD direction of the composite film 7 also coincides with the MD direction of the protective film 9 in the composite film 7. Hereinafter, "MD direction" may be referred to as "flow direction" or "machine direction". The TD direction of the composite film 7 is synonymous with the TD direction of the thermoplastic resin film 81 in the composite film 7. That is, the TD direction of the composite film 7 coincides with the TD direction of the thermoplastic resin film 81 in the composite film 7. The TD direction of the composite film 7 also coincides with the TD direction of the protective film 9 in the composite film 7. Hereinafter, "TD direction" may be referred to as "width direction" or "Transverse Direction".

[0021] <1.1. Paint Replacement Film> The paint-alternative film 8 includes a thermoplastic resin film 81, an adhesive layer 82, a coloring layer 83, and a surface protection layer (hereinafter sometimes referred to as the "hard coat layer") 84. In the paint-alternative film 8, the biaxially oriented polyester film 81, adhesive layer 82, coloring layer 83, and surface protection layer 84 are stacked in this order.

[0022] <1.1.1. Thermoplastic resin film>

[0023] Examples of thermoplastic resin films 81 include polyolefin films, polyamide films, acrylic resin films, polyester films, polycarbonate films, and polyarylene sulfide films. Among these, polyester films (for example, biaxially oriented polyester films) are preferred, polyethylene terephthalate films (for example, biaxially oriented polyethylene terephthalate films) are more preferred, and biaxially oriented polyethylene terephthalate films are even more preferred.

[0024] In the following explanation, we will assume that the thermoplastic resin film 81 is a biaxially oriented polyester film. Explanations of thermoplastic resin films 81 other than biaxially oriented polyester films (e.g., polyolefin films, polyamide films) will be omitted as they overlap with the following explanation of biaxially oriented polyester films. The following explanation of biaxially oriented polyester films can also be treated as a general explanation of thermoplastic resin films 81.

[0025] The thickness of the biaxially oriented polyester film 81 is preferably 10 μm or more, more preferably 15 μm or more, even more preferably 20 μm or more, and even more preferably 30 μm or more. A thickness of 10 μm or more facilitates film formation and also facilitates the formation of functional layers such as the colored layer 83 and the surface protective layer 84. In addition, the handling properties of these layers when laminating the composite film 7 to the metal plate 5 are also good. On the other hand, the thickness of the biaxially oriented polyester film 81 is preferably 200 μm or less, more preferably 150 μm or less, even more preferably 125 μm or less, even more preferably 100 μm or less, and even more preferably 75 μm or less. A thickness of 200 μm or less prevents the load required for press processing of the laminate 4 from becoming excessively large.

[0026] The biaxially oriented polyester film 81 includes a B layer (i.e., the first layer) 811 and an A layer (i.e., the second layer) 812. The B layer 811 is located closer to the colored layer 83 than the A layer 812. The B layer 811 is located between the A layer 812 and the adhesive layer 82.

[0027] It is preferable that the melting point of layer B 811 (hereinafter sometimes referred to as "TmB") is higher than the melting point of layer A 812 (hereinafter sometimes referred to as "TmA"). In other words, it is preferable that the melting point of layer A 812 is lower than the melting point of layer B 811. This makes it possible to lower the temperature when laminating the composite film 7 to the metal plate 5, i.e., the thermocompression temperature, compared to the case where the biaxially oriented polyester film 81 consists only of layer B 811.

[0028] The difference between the melting point of layer B 811 and the melting point of layer A 812 is preferably 20°C or higher, more preferably 25°C or higher, even more preferably 28°C or higher, and even more preferably 30°C or higher. A difference of 20°C or higher reduces the deterioration of the surface shape of the biaxially oriented polyester film 81 that may occur due to the heat received by the coating substitute film 8 when the composite film 7 is laminated (specifically, heat-pressed) to the metal plate 5, and also reduces the viscosity of layer A 812 when the composite film 7 is laminated to the metal plate 5. On the other hand, the difference between the melting point of layer B 811 and the melting point of layer A 812 is preferably 70°C or lower, more preferably 60°C or lower, and even more preferably 50°C or lower. A difference of 70°C or lower results in good handling during film formation.

[0029] The ratio of the thickness of layer B 811 to the thickness of layer A 812 (i.e., thickness of layer B 811 / thickness of layer A 812) is preferably 1.5 or more, and more preferably 2.0 or more. A ratio of 1.5 or more reduces the deterioration of the appearance of the coating substitute film 8 that may occur due to the heat received by the coating substitute film 8 when the composite film 7 is laminated (specifically, heat-pressed) to the metal plate 5. In addition, it reduces or prevents the deterioration of the appearance of the coating substitute film 8 that may occur due to the heat received by the coating substitute film 8 when the laminate 4 is press-formed. On the other hand, the ratio of the thickness of layer B 811 to the thickness of layer A 812 (i.e., thickness of layer B 811 / thickness of layer A 812) is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less.

[0030] The thickness of layer B 811 is preferably 20 μm or more, more preferably 25 μm or more, and even more preferably 30 μm or more. A thickness of 20 μm or more reduces the deterioration of the surface shape of the biaxially oriented polyester film 81 that may occur due to the heat received by the paint substitute film 8 when the composite film 7 is laminated (specifically, heat-pressed) to the metal plate 5. In addition, it reduces or prevents the deterioration of the appearance of the paint substitute film 8 that may occur due to the heat received by the paint substitute film 8 when the laminate 4 is press-formed. The thickness of layer B 811 is preferably 150 μm or less, more preferably 100 μm or less, even more preferably 75 μm or less, and even more preferably 50 μm or less.

[0031] The melting point of layer B 811 is preferably 250°C or higher, more preferably 252°C or higher, and even more preferably 253°C or higher. On the other hand, the melting point of layer B 811 may be 260°C or lower, or 258°C or lower.

[0032] Layer B 811 contains a first polyester, i.e., a first polyester resin. The intrinsic viscosity, i.e., the intrinsic viscosity of the first polyester, is preferably 0.60 dL / g or higher. A viscosity of 0.60 dL / g or higher reduces the generation of thermally degraded products derived from low molecular weight components. On the other hand, the intrinsic viscosity of the first polyester is preferably less than 0.95 dL / g.

[0033] The first polyester is preferably a crystalline polyester. If the first polyester is a crystalline polyester, it is possible to reduce uneven stretching of the paint substitute film 8 that may occur when the laminate 4 is press-formed. This will be explained. When the laminate 4 is press-formed, the paint substitute film 8 is partially stretched by the press-formed material. If the B layer 811 of the biaxially oriented polyester film 81 contains crystalline polyester, it is possible for the crystallization of the crystalline polyester to progress more in the part that is stretched the most (i.e., the part with the greatest deformation) than in the surrounding area (i.e., the area around the part with the greatest deformation). Therefore, at the beginning of the press-formed material, the paint substitute film 8 stretches easily in the part with the greatest deformation, but as the press-formed material progresses, the part with the greatest deformation itself becomes less stretchable. As a result, the surrounding area (i.e., the area around the part with the greatest deformation) stretches. Therefore, it is possible to prevent the thickness of the part with the greatest deformation from becoming excessively thin. Hence, uneven stretching of the paint substitute film 8 can be reduced. Crystalline polyester refers to polyester in which an endothermic peak of 0.05 J / g or more appears in the differential scanning calorimetry (DSC) curve at a temperature higher than the baseline shift corresponding to the glass transition point, due to crystal melting. In differential scanning calorimetry to obtain the DSC curve, a sample is scraped from layer B 811, 10 mg of the sample is heated to 290°C at 20°C / min, isothermal for 3 minutes, rapidly cooled at 200°C / min, and heated to 290°C at 10°C / min. A DSC-60 differential scanning calorimeter is used for differential scanning calorimetry.

[0034] Examples of the first polyester include polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate. Among these, polyethylene terephthalate and polybutylene terephthalate are preferred, and polyethylene terephthalate is more preferred. Examples of polyethylene terephthalate include homo-polyethylene terephthalate and copolymerized polyethylene terephthalate. Among these, homo-polyethylene terephthalate is preferred. Homo-polyethylene terephthalate may contain diethylene glycol components that may be produced as by-products during its manufacture. On the other hand, examples of copolymerization components for obtaining copolymerized polyethylene terephthalate, particularly dicarboxylic acids, include aromatic carboxylic acids such as isophthalic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid; aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid; and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. One or more of these can be used. Copolymerization components for obtaining copolymerized polyethylene terephthalate, particularly diols, include aliphatic diols such as trimethylene glycol (propanediol), butanediol, and hexanediol; and alicyclic diols such as cyclohexanedimethanol. One or more of these can be used. Among these, isophthalic acid and sebacic acid are preferred, with isophthalic acid being more preferred.

[0035] Therefore, the first polyester may have at least one of butylene terephthalate units and ethylene isophthalate units. Preferably, the total amount of butylene terephthalate units and ethylene isophthalate units in the first polyester is 80 mol% or more.

[0036] The content of the first polyester is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 75% by mass or more, when the B layer 811 is considered to be 100% by mass. The content of the first polyester is, for example, 80% by mass or more, 90% by mass or more, or 95% by mass or more, when the B layer 811 is considered to be 100% by mass. On the other hand, the content of the first polyester is, for example, 100% by mass, 99% by mass or less, 98% by mass or less, 95% by mass or less, or 90% by mass or less, when the B layer 811 is considered to be 100% by mass.

[0037] Layer B 811 may contain additives. Examples of additives include coloring pigments, fluorescent whitening agents, inert particles, antioxidants, heat stabilizers, ultraviolet absorbers, and antistatic agents. Examples of coloring pigments include inorganic pigments and organic pigments. Inorganic pigments are preferred among these. Examples of inorganic pigments include alumina, titanium dioxide, calcium carbonate, and barium sulfate. Titanium dioxide is preferred among these when imparting opacity to layer B 811. The content of the coloring pigment may be 2% by mass or more, 4% by mass or more, or 10% by mass or more, when layer B 811 is considered to be 100% by mass. On the other hand, the content of the coloring pigment may be 50% by mass or less, 40% by mass or less, or 35% by mass or less, when layer B 811 is considered to be 100% by mass. Fluorescent whitening agents can improve whiteness.

[0038] Inert particles can improve the handling, specifically the slipperiness, of the biaxially oriented polyester film 81. Examples of inert particles include polymers or copolymers of monomers selected from polystyrene, methyl polyacrylate, ethyl polyacrylate, methyl polymethacrylate, ethyl polymethacrylate, and divinylbenzene, as well as organic materials such as polytetrafluoroethylene, polyacrylonitrile, benzoguanamine, and silicone. Inorganic materials such as silica, kaolin, talc, and graphite can also be used. Among these, inorganic materials are preferred, and silica, i.e., silica particles, are more preferred. The particle size of the inert particles is preferably 0.02 μm or larger, and more preferably 0.1 μm or larger. On the other hand, the particle size of the inert particles is preferably 10 μm or smaller, and more preferably 2 μm or smaller. The content of inert particles is preferably 0.002% to 0.5% by mass, when the B layer 811 is considered as 100% by mass.

[0039] The thickness of layer A 812 is preferably 5 μm or more, more preferably 8 μm or more, and even more preferably 10 μm or more. If it is 5 μm or more, it is possible to fill any irregularities that may exist on the metal plate 5, and therefore the adhesion strength with the metal plate 5 can be improved. The thickness of layer A 812 is preferably 30 μm or less, more preferably 25 μm or less, even more preferably 20 μm or less, and even more preferably 15 μm or less.

[0040] The melting point of layer A 812 is preferably 160°C or higher, more preferably 180°C or higher, and even more preferably 200°C or higher. On the other hand, the melting point of layer A 812 is preferably 250°C or lower, more preferably 240°C or lower, and even more preferably 230°C or lower.

[0041] Layer A 812 contains a second polyester, i.e., a second polyester resin. The intrinsic viscosity of the second polyester is preferably 0.60 dL / g or higher. On the other hand, the intrinsic viscosity of the first polyester is preferably less than 0.95 dL / g. If it is less than 0.95 dL / g, it is possible to reduce the viscosity of layer A 812 when laminating (specifically, heat-pressing) the composite film 7 to the metal plate 5, and therefore, the adhesion strength to the metal plate 5 can be improved.

[0042] The second polyester is preferably a crystalline polyester. A crystalline polyester is a polyester that, in the differential scanning calorimetry (DSC) curve, exhibits an endothermic peak of 0.05 J / g or more at a temperature higher than the temperature at which the baseline shift corresponding to the glass transition occurs, due to crystal melting. For differential scanning calorimetry to obtain the DSC curve, a sample is scraped from layer A 812, 10 mg of the sample is heated to 290°C at 20°C / min, isothermal for 3 minutes, rapidly cooled at 200°C / min, and heated to 290°C at 10°C / min. A DSC-60 differential scanning calorimeter is used for differential scanning calorimetry.

[0043] Examples of the second polyester include polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate. Among these, polyethylene terephthalate is preferred. Examples of polyethylene terephthalate include homopolymer polyethylene terephthalate and copolymerized polyethylene terephthalate. Among these, copolymerized polyethylene terephthalate is preferred. The explanation of copolymerized polyethylene terephthalate in the second polyester overlaps with the explanation of copolymerized polyethylene terephthalate in the first polyester, so it is omitted. Therefore, the explanation of copolymerized polyethylene terephthalate in the first polyester can also be treated as the explanation of copolymerized polyethylene terephthalate in the second polyester.

[0044] Therefore, the second polyester may have at least one of butylene terephthalate units and ethylene isophthalate units. Preferably, the total amount of butylene terephthalate units and ethylene isophthalate units in the second polyester is 80 mol% or more.

[0045] The content of the second polyester is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, when the A layer 812 is considered to be 100% by mass. On the other hand, the content of the second polyester may be, for example, 100% by mass, 99% by mass or less, 98% by mass or less, or 95% by mass or less, when the A layer 812 is considered to be 100% by mass.

[0046] Layer A 812 may contain additives. Examples of additives include coloring pigments, fluorescent whitening agents, inert particles, antioxidants, heat stabilizers, ultraviolet absorbers, and antistatic agents.

[0047] The biaxially oriented polyester film 81 can be produced by a procedure in which an unstretched polyester film is prepared, and then the unstretched polyester film is biaxially stretched. For example, the biaxially oriented polyester film 81 can be produced by a procedure in which a molding material for forming layer B 811 (i.e., a polyester composition containing a first polyester) is supplied to a first extruder, and a molding material for forming layer A 812 (specifically, a polyester composition containing a second polyester) is supplied to a second extruder, then the molding material is guided from the first extruder to a feed block, and the molding material is guided from the second extruder to a feed block, and these molding materials are laminated in the feed block, then the unstretched polyester film (hereinafter sometimes referred to as "sheet") is melt-extruded from the die, then the unstretched polyester film is solidified in a cooling drum, the unstretched polyester film is biaxially stretched, and then heat-fixed. Alternatively, the film can be manufactured by supplying raw materials for forming layer B 811 to a first extruder and raw materials for forming layer A 812 to a second extruder, then guiding the molding material from the first extruder to a multi-manifold die and guiding the molding material from the second extruder to a multi-manifold die, laminating these molding materials in the multi-manifold die, then melt-extruding the unstretched polyester film from the multi-manifold die, then solidifying the unstretched polyester film in a cooling drum, biaxially stretching the unstretched polyester film, and heat-setting it. The biaxial stretching may be simultaneous biaxial stretching in the longitudinal and transverse directions, or sequential biaxial stretching. Sequential biaxial stretching is preferred. In sequential biaxial stretching, for example, it is preferable to stretch the sheet that has passed through the cooling roll in the flow direction, i.e., the Machine Direction (i.e., MD direction), and then stretch the sheet after stretching in the MD direction in the width direction, i.e., the Transverse Direction (i.e., TD direction). Furthermore, a surface treatment may be applied to the sheet between the first stretching (for example, stretching in the flow direction) and the second stretching (for example, stretching in the width direction). For example, an adhesive layer 82 may be formed between the first stretching and the second stretching.

[0048] Regarding extrusion, in the first extruder, it is preferable to supply the molding material for forming layer B 811, i.e., the polyester composition containing the first polyester, to the first extruder after it has been thoroughly dried, and to melt it at a temperature of ~(melting point + 50)°C of the first polyester. On the other hand, in the second extruder, it is preferable to supply the molding material for forming layer A 812, i.e., the polyester composition containing the second polyester, to the second extruder after it has been thoroughly dried, and to melt it at a temperature of ~(melting point + 50)°C of the second polyester. At least one of the molding material for forming layer B 811 and the molding material for forming layer A 812 may contain inert particles.

[0049] When biaxial stretching is sequential biaxial stretching, the unstretched polyester film can be heated and stretched in the flow direction. Examples of heating methods for the unstretched polyester film include roll heating and infrared heating. The stretching temperature in the flow direction is preferably 70°C or higher, and more preferably 80°C or higher. A temperature of 70°C or higher can reduce the occurrence of breakage. On the other hand, the stretching temperature in the flow direction is preferably 110°C or lower, and more preferably 100°C or lower. A temperature of 110°C or lower can avoid excessively low orientation.

[0050] A stretching ratio in the flow direction is preferably 3.0 times or more. A ratio of 3.0 times or more makes it possible to avoid excessively low orientation. In addition, it reduces or avoids the occurrence of excessive thickness unevenness, and reduces or avoids the occurrence of excessive looseness that may occur when the biaxially oriented polyester film 81 is wound into a roll. On the other hand, a stretching ratio in the flow direction is preferably 5.0 times or less, more preferably 4.5 times or less, and even more preferably 4.0 times or less. A ratio of 5.0 times or less allows for effective enjoyment of the effect of improving thickness unevenness due to stretching. As an example of a stretching method in the flow direction, a method can be given in which a heated unstretched polyester film is stretched by the speed difference between rolls.

[0051] A polyester film stretched in the flow direction can be stretched in the width direction. A stretching temperature of 90°C or higher is preferable, as this reduces the occurrence of breakage. On the other hand, a stretching temperature of 130°C or lower is preferable, as this avoids excessively low orientation.

[0052] The stretching ratio in the width direction is preferably 3.0 times or more, and more preferably 3.5 times or more. A ratio of 3.0 times or more makes it possible to avoid excessively low orientation. In addition, it is possible to reduce or avoid the occurrence of excessive thickness unevenness, and to reduce or avoid the occurrence of excessive looseness that may occur when the biaxially oriented polyester film 81 is wound into a roll. On the other hand, the stretching ratio in the width direction is preferably 5.0 times or less, and more preferably 4.5 times or less. A ratio of 5.0 times or less makes it possible to effectively enjoy the effect of improving thickness unevenness due to stretching.

[0053] It is preferable to perform a heat-setting treatment after biaxial stretching. The heat-setting temperature may be, for example, 165°C or higher, or 170°C or higher. The heat-setting temperature may be, for example, 240°C or lower, or 230°C or lower.

[0054] A thermal relaxation treatment may be performed in conjunction with or separately from the thermal setting treatment. In the thermal relaxation treatment, relaxation is preferably performed in at least one of the flow direction (i.e., the MD direction) and the width direction (i.e., the TD direction). Relaxation in the width direction is particularly preferred.

[0055] <1.1.2.Adhesive layer> The adhesive layer 82 is located between the biaxially oriented polyester film 81 and the colored layer 83. Specifically, the adhesive layer 82 is located between the B layer 811 of the biaxially oriented polyester film 81 and the colored layer 83. The adhesive layer 82 can improve the adhesion between the biaxially oriented polyester film 81 and the colored layer 83. Mechanisms for improving adhesion include, for example, bond formation between functional groups, reduction of interlayer interface energy, and interlayer interface mixing. The adhesive layer 82 can also be referred to as the easy-adhesion layer 82.

[0056] The thickness of the adhesive layer 82 is preferably 5 nm or more, and more preferably 10 nm or more, from the viewpoint of adhesion. On the other hand, the thickness of the adhesive layer 82 is preferably 200 nm or less, more preferably 180 nm, even more preferably 150 nm, and even more preferably 120 nm or less, from the viewpoint of thickness unevenness and adhesion.

[0057] The adhesive layer 82 contains a resin. Examples of resins include polyurethane resins, vinyl chloride / vinyl acetate copolymer resins, vinyl chloride / vinyl acetate / acrylic copolymer resins, chlorinated polypropylene resins, acrylic resins, polyester resins, polyamide resins, butyral resins, polystyrene resins, nitrocellulose resins, and cellulose acetate resins. One or more of these can be used. Among these, acrylic resins and polyester resins are preferred. Considering that heat is generated by shear when the laminate 4 is press-formed, and the laminate 4 may reach a temperature of about 150°C, the glass transition temperature of the resin is preferably 150°C or lower.

[0058] The resin preferably has at least one functional group selected from the group consisting of epoxy groups, oxazoline groups, silanol groups, and isocyanate groups. Among these, epoxy groups and oxazoline groups are preferred as functional groups because they can further improve adhesion with layer B 811.

[0059] The adhesive layer 82 can be formed on the biaxially oriented polyester film 81 by any method. For example, the adhesive layer 82 may be formed by in-line coating, where the coating is applied while the biaxially oriented polyester film 81 is being formed. Alternatively, the adhesive layer 82 may be formed by off-line coating, where the biaxially oriented polyester film 81 is formed, wound into a roll, and then unwound and coated.

[0060] <1.1.3. Colored layer> The colored layer 83 is located between the adhesive layer 82 and the surface protection layer 84. The colored layer 83 is provided on the adhesive layer 82. The colored layer 83 can be used to decorate or protect the metal plate 5.

[0061] The thickness of the colored layer 83 is preferably 2 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. On the other hand, the thickness of the colored layer 83 is preferably 100 μm or less, more preferably 75 μm or less, even more preferably 50 μm or less, even more preferably 40 μm or less, and even more preferably 30 μm or less. The colored layer 83 may be a single layer or a multi-layer structure.

[0062] The colored layer 83 contains a coloring agent. Examples of coloring agents include pigments and dyes. Examples of pigments and dyes include carbon black (ink), iron black, titanium white, antimony white, lead yellow, titanium yellow, reddish-brown, cadmium red, ultramarine, cobalt blue, quinacridone red, isoindolinone yellow, phthalocyanine blue, aluminum, brass, titanium dioxide, and pearlescent pigments. As described above, the colored layer 83 may be a single layer or a multi-layer structure. For example, if the colored layer 83 is a two-layer structure, it may be preferable that one of the two layers contains a luminescent pigment. For example, if the colored layer 83 is a two-layer structure, it may be preferable that the layer closer to the biaxially oriented polyester film 81 contains an aluminum pigment and the layer closer to the surface protection layer 84 contains a pigment.

[0063] The coloring agent content is preferably 0.5% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more, when the colored layer 83 is considered to be 100% by mass. On the other hand, the coloring agent content is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less, when the colored layer 83 is considered to be 100% by mass.

[0064] It is preferable that the colored layer 83 contains a resin (hereinafter sometimes referred to as "binder resin"). Because the colored layer 83 contains a binder resin, the occurrence of cracks in the colored layer 83 can be reduced when the laminate 4 is press-formed. Examples of binder resins include acrylic resin, urethane resin, polyester resin, and PVDF (polyvinylidene fluoride). One or more of these can be used. Among these, acrylic resin is preferred.

[0065] The colored layer 83 can be formed on the adhesive layer 82 by any method. Coating is preferred because it allows for easy formation of the colored layer 83.

[0066] <1.1.4.Surface protective layer> The surface protection layer 84 is provided on the colored layer 83. The surface protection layer 84 can reduce scratches on the colored layer 83 and the biaxially oriented polyester film 81 (i.e., it can improve scratch resistance). In addition, the surface protection layer 84 may improve adhesion with the protective film 9. The surface protection layer 84 is preferably transparent. The surface protection layer 84 is preferably weather resistant. The surface protection layer 84 may also be glossy.

[0067] The thickness of the surface protection layer 84 is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more. This is because the thicker the surface protection layer 84, the more it is possible to reduce scratches on the colored layer 83 and the biaxially oriented polyester film 81 (i.e., to improve scratch resistance), and also to improve chemical resistance. On the other hand, the thickness of the surface protection layer 84 is preferably 80 μm or less, more preferably 60 μm or less, and even more preferably 50 μm or less. This is because the thinner the surface protection layer 84, the more economical it is. The surface protection layer 84 may be a single layer or a multi-layer structure.

[0068] The surface protection layer 84 is curable. That is, the degree of curing in the surface protection layer 84 is incomplete. Here, incomplete curing means that the curing has not reached its final stage. Because the surface protection layer 84 is curable, i.e., incompletely cured, it can follow the deformation of the metal plate 5 when the laminate 4 is press-formed. In addition, curing the surface protection layer 84 can effectively protect the surface of the colored layer 83. The degree of curing can be, for example, stage B.

[0069] It is preferable that the surface protection layer 84 contains at least one of a thermosetting resin and a photocurable resin. In other words, it is preferable that the surface protection layer 84 is thermosetting or photocurable. Thermosetting is preferred. That is, it is preferable that the surface protection layer 84 contains a thermosetting resin. This is because the heat generated by shearing when the laminate 4 is press-formed allows the thermosetting to proceed. Examples of thermosetting resins include acrylic resin, melamine resin, and urethane resin. Acrylic resin is preferred among these. One or more of these can be used. It is preferable that the surface protection layer 84 does not contain polyester containing alkylene terephthalate units. It is preferable that the surface protection layer 84 contains a crosslinking agent. The surface protection layer 84 may also contain other additives.

[0070] The surface protection layer 84 can be formed on the colored layer 83 by any method. For example, the surface protection layer 84 can be formed by coating, melt extrusion, lamination, etc. Among these, coating is preferred because it allows for easy formation of the surface protection layer 84. When forming a two-layer surface protection layer 84, that is, when coating the surface protection layer 84 with paint twice, the drying conditions for the first and second coats may be changed to adjust the degree of hardening of each layer.

[0071] <1.2. Protective film> A protective film 9 is provided on the surface protective layer 84 of the paint substitute film 8. The protective film 9 prevents the paint substitute film 8 from being scratched and also prevents dirt from adhering to the paint substitute film 8.

[0072] The thickness of the protective film 9 is preferably 10 μm or more, more preferably 25 μm or more, even more preferably 35 μm or more, and even more preferably 38 μm or more. A thickness of 10 μm or more provides excellent rigidity. The thickness of the protective film 9 is preferably 150 μm or less, more preferably 100 μm or less, even more preferably 80 μm or less, and even more preferably 70 μm or less. This is because the thinner the protective film 9, the more economical it is. The protective film 9 may be a single-layer structure or a multi-layer structure.

[0073] The protective film 9 preferably contains a thermoplastic resin. Examples of thermoplastic resins include polyolefin resins, polyamide resins, acrylic resins, polyester resins, polycarbonate resins, and polyarylene sulfide resins. Examples of polyolefin resins include polyethylene resins and polypropylene resins. In particular, when the biaxially oriented polyester film 81 is a biaxially oriented polyethylene terephthalate film, polyethylene resin, i.e., polyethylene, is preferred. In other words, it is preferable that the protective film 9 is a polyethylene film. Examples of polyethylene include high-pressure low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE).

[0074] It is more preferable that the protective film 9 contains high-pressure low-density polyethylene (LDPE). The density of LDPE is 0.910 g / cm³. 3 More than 0.930g / cm 3 The following is also acceptable.

[0075] The protective film 9 may also preferably contain high-pressure low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE). The density of LLDPE is 0.910 g / cm³. 3More than 0.925g / cm 3 The following is also acceptable.

[0076] When protective film 9 contains LDPE, the density of protective film 9 is 0.910 g / cm³. 3 More than 0.928g / cm 3 The following is also acceptable: 0.910 g / cm³ 3 This reduces the possibility of wrinkles occurring during the manufacturing of the protective film 9.

[0077] When the protective film 9 contains LDPE, the melt flow rate (MFR) of the protective film 9 may be between 1.0 g / 10 min and 10 g / 10 min. A MFR of 1.0 g / 10 min or higher can prevent excessively poor fluidity of the polyethylene when forming the protective film 9. A MFR of 10 g / 10 min or lower can prevent the inflation tube from becoming excessively unstable when forming the protective film 9 by the inflation method. The MFR can be measured at 190°C and under a 2.16 kg load in accordance with JIS K7210.

[0078] The LDPE content in the protective film 9 may be, for example, 10% by mass or more, 50% by mass or more, or 95% by mass or more.

[0079] When the protective film 9 contains LDPE and LLDPE, the total content of LDPE and LLDPE in the protective film 9 is preferably 90% by mass or more, and more preferably 95% by mass or more.

[0080] When the total content of LDPE and LLDPE is set to 100% by mass, the LLDPE content may be, for example, 45% by mass or less, or 40% by mass or less. A content of 45% by mass or less can reduce the fish-eye effect that may occur on the protective film 9. The LLDPE content may be, for example, 5% by mass or more, or 10% by mass or more.

[0081] The protective film 9 may contain additives. Examples of additives include plasticizers, antiblocking agents, antistatic agents, and nucleating agents.

[0082] The protective film 9 can be manufactured, for example, by the inflation method or the T-die method. Among these, the inflation method is preferred because it can minimize the difference between the physical properties of the protective film 9 in the MD direction and the physical properties of the protective film 9 in the TD direction.

[0083] Of the two surfaces of the protective film 9, the surface roughness of at least the surface in contact with the surface protective layer 84 is preferably 1 nm or more, more preferably 3 nm or more, and even more preferably 10 nm or more. If it is 10 nm or more, the transportability of the protective film 9 is good, and therefore the handling is good. Since the surface shape of the protective film 9 can be transferred to the surface protective layer 84, the surface roughness of the protective film 9 (specifically, the surface roughness of at least the surface in contact with the surface protective layer 84) is preferably 1000 nm or less, more preferably 800 nm or less, and even more preferably 500 nm or less.

[0084] At least one of the two surfaces of the protective film 9 that is in contact with the surface protective layer 84 may be subjected to a delamination treatment. For example, silicone-based delaminating agents, fluorine-based delaminating agents, and long-chain aliphatic delaminating agents can be used for the delamination treatment. Among these, silicone-based delaminating agents are preferred because they are inexpensive.

[0085] The protective film 9 can be formed on the surface protective layer 84 of the paint-alternative film 8 by any method. For example, the protective film 9 can be formed by coating, melt extrusion, lamination, etc. Among these, lamination, i.e., laminating the protective film 9 onto the paint-alternative film 8, is preferred.

[0086] <1.3.S mt / S mp > S mt / S mpThat is, the 5% strain tensile stress (S) in the MD direction in the biaxially oriented polyester film 81. mt ) the 5% strain tensile stress (S) in the MD direction in the protective film 9 mp The ratio to ) is 5.0 or greater. mt / S mp For example, it may be 5.5 or higher, or 5.8 or higher. mt / S mp Since the value is 5.0 or higher, peeling of the protective film 9 during press working can be suppressed or reduced. This will be explained. When the laminate 4 (i.e., the laminate 4 including the metal plate 5 and the composite film 7 laminated on the metal plate 5) is press-worked, a force acts on the laminate 4 (for example, a force pulling the laminate 4 along the main surface direction of the laminate 4. Needless to say, other forces act in some parts). This force (i.e., the force acting on the laminate 4 during press working) tends to act in the order of metal plate 5, paint substitute film 8, and protective film 9. Here, since the surface protective layer 84 of the paint substitute film 8 is curable, that is, the surface protective layer 84 is not fully cured, the stress generated in the surface protective layer 84 by this force is not large. As a result, the force acting on the protective film 9 among the forces acting on the laminate 4 during press working is moderate. If the 5% strain tensile stress (S) of the protective film 9 in the MD direction is mp ) is that of the biaxially oriented polyester film 81 in the MD direction (S mt If the ratio is excessively large in relation to the ), then when the laminate 4 is pressed, the protective film 9 cannot be stretched in the same way as the biaxially oriented polyester film 81, and as a result, the protective film 9 peels off. [1] According to S mt / S mp It is 5.0 or higher, that is, S mp S mt Because it is not excessively large in relation to the other elements, when the laminate 4 is press-formed, the protective film 9 can be stretched in the same way as the biaxially oriented polyester film 81, and therefore peeling of the protective film 9 can be suppressed or reduced.

[0087] S mt / Smp It is 10.0 or less. mt / S mp For example, it may be 9.4 or less, or 9.0 or less. mt / S mp The value is 10.0 or less, that is, the 5% strain tensile stress (S) of the protective film 9 in the MD direction. mp ) is that of the biaxially oriented polyester film 81 in the MD direction (S mt Because it is not excessively small in relation to the other components, it is possible to prevent or reduce excessive stress concentration in the protective film 9 when the laminate 4 is press-formed, and therefore it is possible to suppress or reduce tearing of the protective film 9.

[0088] S mt In other words, the 5% strain tensile stress in the MD direction of the biaxially oriented polyester film 81 may be, for example, 50 MPa or more, or 60 MPa or more. mt For example, it may be 150 MPa or less, or 130 MPa or less.

[0089] <1.4.S tt / S tp > S tt / S tp That is, the 5% strain tensile stress (S) in the TD direction of the biaxially oriented polyester film 81. tt ) The 5% strain tensile stress (S) in the TD direction in the protective film 9 tp The ratio to ) is 5.0 or greater. tt / S tp For example, it may be 5.5 or higher, or 5.8 or higher. tt / S tp Since the value is 5.0 or higher, peeling of the protective film 9 during press processing can be further suppressed or reduced.

[0090] S tt / S tp It is 10.0 or less. tt / S tpFor example, it may be 9.4 or less, or 9.0 or less. tt / S tp Since the value is 10.0 or less, it is possible to further prevent or reduce excessive stress concentration in the protective film 9 when the laminate 4 is press-formed, and therefore further suppress or reduce tearing of the protective film 9.

[0091] S tt In other words, the 5% strain tensile stress in the TD direction of the biaxially oriented polyester film 81 may be, for example, 50 MPa or more, or 60 MPa or more. tt For example, it may be 150 MPa or less, or 130 MPa or less.

[0092] <2. Laminate> As shown in Figure 2, the laminate 4 includes a metal plate 5 and a composite film 7 laminated to the metal plate 5. In the laminate 4, the metal plate 5, the coating substitute film 8, and the protective film 9 are stacked in this order. In the laminate 4, a biaxially oriented polyester film 81 is provided on the metal plate 5. Layer A 812 of the biaxially oriented polyester film 81 is located between the metal plate 5 and layer B 811. Layer A 812 adheres the metal plate 5 and layer B 811.

[0093] <2.1. Metal plate> Examples of metal plates 5 include steel plates, aluminum alloy plates, and magnesium alloy plates. Among these, steel plates are preferred. Examples of steel plates include stainless steel plates. These may be pre-treated with zinc alloy plating or chromium plating. In other words, the steel plates may be surface-treated steel plates. Examples of surface-treated steel plates include tin-free steel plates and tinplate. In particular, when the laminate 4 is used to manufacture vehicle exterior parts, the metal plate 5 is preferably a steel plate with zinc alloy plating. Zinc alloy plating can improve corrosion resistance.

[0094] The thickness of the metal plate 5 may be, for example, 0.2 mm or more, 0.3 mm or more, 0.4 mm or more, or 0.6 mm or more. On the other hand, the thickness of the metal plate 5 may be, for example, 1.4 mm or less, 1.2 mm or less, 1.0 mm or less, or 0.8 mm or less. In particular, for good formability, the thickness of the metal plate 5 is preferably 0.2 mm or more and 1.4 mm or less, more preferably 0.3 mm or more and 1.2 mm or less, and even more preferably 0.3 mm or more and 1.0 mm or less. If the metal plate 5 is a steel plate with zinc alloy plating, the thickness of the metal plate 5 is preferably 0.4 mm or more and 0.8 mm or less. If the metal plate 5 is an aluminum alloy plate, the thickness of the metal plate 5 is preferably 0.6 mm or more and 1.2 mm or less.

[0095] <2.2. Method for Manufacturing Laminates> The method for manufacturing the laminate 4 includes a step of heating the metal plate 5 (hereinafter sometimes referred to as the "heating step") and a step of pressing the heated metal plate 5 and the composite film 7 together (hereinafter sometimes referred to as the "pressing step"). The method for manufacturing the laminate 4 may further include a step of cooling the metal plate 5 to which the composite film 7 has been pressed (hereinafter sometimes referred to as the "cooling step"). If the metal plate 5 is in the form of a roll and the composite film 7 is also in the form of a roll, the laminate 4 can be manufactured using a roll-to-roll method.

[0096] <2.2.1. Process of heating the metal plate> In this step, the metal plate 5 is heated. By heating the metal plate 5, it becomes possible to heat-press the metal plate 5 and the composite film 7 together.

[0097] <2.2.2. Crimping Process> In this process, the heated metal plate 5 and the composite film 7 are pressed together. Specifically, the A layer 812 of the composite film 7 is facing the heated metal plate 5 when the two are pressed together.

[0098] In this process, it is preferable that the temperature of the heated metal plate 5 is equal to or above the melting point of layer A 812. If the temperature is equal to or above the melting point of layer A 812, it is possible to melt layer A 812, and therefore the metal plate 5 and the composite film 7 can be heat-pressed together. The temperature of the heated metal plate 5 may be equal to or above the sum of the melting point of layer A 812 and 20°C, or equal to or above the sum of the melting point of layer A 812 and 30°C, or equal to or above the sum of the melting point of layer A 812 and 35°C, or equal to or above the sum of the melting point of layer A 812 and 40°C. Therefore, if the melting point of layer A 812 is 217°C, the temperature of the heated metal plate 5 may be 237°C or higher, 247°C or higher, 252°C or higher, or 257°C or higher. When the temperature of the heated metal plate 5 is equal to or greater than the sum of the melting point of layer A 812 and 20°C, it is possible to effectively reduce the viscosity of layer A 812, and therefore improve the adhesion strength to the metal plate 5.

[0099] The temperature of the heated metal plate 5 may be less than or equal to the sum of the melting point of layer B 811 and 10°C, or less than or equal to the sum of the melting point of layer B 811 and 8°C, or less than or equal to the sum of the melting point of layer B 811 and 7°C. Therefore, if the melting point of layer B 811 is 255°C, the temperature of the heated metal plate 5 may be 265°C or less, 263°C or less, or 262°C or less. If the temperature of the heated metal plate 5 is less than or equal to the sum of the melting point of layer B 811 and 10°C, it is possible to avoid excessive melting of the crystals of layer B 811, and therefore, it is possible to avoid an excessive decrease in the heat resistance of the biaxially oriented polyester film 81.

[0100] <2.2.3. Cooling process> In this step, the metal plate 5 to which the composite film 7 is pressed is cooled. Cooling suppresses recrystallization, thus preventing the crystallinity of at least layer A 812 from becoming excessively high after lamination. Therefore, it is possible to prevent the adhesion strength with the metal plate 5 from becoming excessively low. Thus, the occurrence of delamination of the paint substitute film 8 from the metal plate 5, specifically, the occurrence of delamination of the paint substitute film 8 from the metal plate 5 after the laminate 4 has been press-formed, can be reduced or prevented. As an example of a cooling method, the metal plate 5 to which the paint substitute film 8 or composite film 7 is pressed can be water-cooled. Examples of water-cooling methods include immersing the metal plate 5 to which the paint substitute film 8 or composite film 7 is pressed in a water tank, or spraying water onto the metal plate 5 to which the paint substitute film 8 or composite film 7 is pressed. The water in the tank or the water sprayed can be, for example, tap water, well water, rainwater, or pure water. Chemicals may be added to the water. It is preferable that the water in the tank or the water sprayed is cold water. The water temperature may be, for example, 5°C or higher, or 15°C or higher. The water temperature may be 60°C or lower, 45°C or lower, 35°C or lower, or 30°C or lower.

[0101] To effectively suppress recrystallization, it is preferable to start cooling within 5 seconds of pressing the heated metal plate 5 and the composite film 7 together (for example, immersing the metal plate 5 with the composite film 7 pressed onto it in a water bath within 5 seconds of pressing). For example, it may be within 3 seconds or within 2 seconds.

[0102] <3. Molded products> The molded product of this embodiment can be obtained by press forming, i.e., press molding, of the laminate 4. Cold press forming is preferred as the press forming method. Cold press forming may be, for example, deep drawing, i.e., deep drawing, or stretch forming, i.e., stretching. After press forming, the surface protective layer 84 may be cured as needed. After press forming, the protective film 9 may be peeled off from the paint substitute film 8 as needed.

[0103] The molded product can be used, for example, in vehicles, ships (e.g., motorboats), home appliances, and audio products. Vehicles are particularly preferred. Examples of vehicles include automobiles, motorcycles, railway vehicles, and airplanes. Automobiles and motorcycles are particularly preferred. When the molded product is used in a vehicle, it is preferable to use it as a vehicle exterior part. As a vehicle exterior part, an exterior panel is preferred, and an automobile exterior panel is more preferred. The molded product may also be used as a construction member or a steel plate product.

[0104] <4. Various modifications can be made to the embodiments described above.> Various modifications can be made to the embodiments described above. For example, one or more of the following modifications can be selected to modify the embodiments described above.

[0105] In the above-described embodiment, a configuration was described in which the composite film 7 has only a coating substitute film 8 and a protective film 9. However, this embodiment is not limited to this configuration. The composite film 7 may further include other films.

[0106] In the above-described embodiment, a configuration was described in which the coating substitute film 8 includes an adhesive layer 82. However, this embodiment is not limited to this configuration. That is, the laminate 4 does not have to include an adhesive layer 82.

[0107] In the above-described embodiment, a configuration was described in which the colored layer 83 is provided on the adhesive layer 82. However, this embodiment is not limited to this configuration. Other layers may be present between the adhesive layer 82 and the colored layer 83.

[0108] In the above-described embodiment, a configuration was described in which the surface protection layer 84 is provided on the colored layer 83. However, this embodiment is not limited to this configuration. Other layers may be present between the colored layer 83 and the surface protection layer 84.

[0109] In the above-described embodiment, a configuration was described in which the protective film 9 is provided on the surface protective layer 84. However, this embodiment is not limited to this configuration. Other layers may be present between the surface protective layer 84 and the protective film 9.

[0110] In the above-described embodiment, a configuration was described in which the biaxially oriented polyester film 81 includes a B layer 811 and an A layer 812. However, this embodiment is not limited to this configuration. For example, the biaxially oriented polyester film 81 may include only one of the B layer 811 and the A layer 812. The biaxially oriented polyester film 81 may include other layers between the B layer 811 and the A layer 812. [Examples]

[0111] The present invention will be described in more detail below with reference to examples and comparative examples. Hereafter, unless otherwise specified, "parts" means "parts by mass" and "%" means "percent mass".

[0112] <Measurement methods for each physical property> <Intrinsic viscosity> 0.2 g of polyester resin was dissolved in 50 ml of a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (60 / 40 (mass ratio)), and the intrinsic viscosity (IV) was measured at 30°C using an Ostwald viscometer. The unit is dL / g.

[0113] <Thickness> The thickness of the protective film and the easy-adhesion film was measured using a dot-type thickness gauge.

[0114] <Tensile stress of protective film at 5% strain> A test specimen measuring 150 mm in length and 10 mm in width (hereinafter sometimes referred to as the "protective film MD test specimen") was cut from the protective film so that the MD direction of the protective film was aligned with the length direction of the test specimen. A tensile test was performed on the protective film MD test specimen using a tensile testing machine (manufactured by Instron Co., Ltd.) at a chuck distance of 100 mm and a tensile speed of 100 mm / min under conditions of 23°C and 50% RH. From the obtained results, the stress when the strain reached 5%, i.e., the 5% strain tensile stress (hereinafter sometimes referred to as "F5") was determined. A test specimen measuring 150 mm in length and 10 mm in width (hereinafter sometimes referred to as the "protective film TD test specimen") was cut from the protective film so that the TD direction of the protective film was aligned with the length direction of the test specimen. A tensile test of the protective film TD test specimen was performed under the same conditions as the tensile test of the protective film MD test specimen, and the 5% strain tensile stress was determined.

[0115] <Tensile stress of thermoplastic resin film at 5% strain> A test specimen measuring 150 mm in length and 10 mm in width (hereinafter sometimes referred to as the "thermoplastic resin film MD test specimen") was cut from the thermoplastic resin film so that the MD direction of the thermoplastic resin film was aligned with the length direction of the test specimen. A tensile test of the thermoplastic resin film MD test specimen was performed under the same conditions as the tensile test of the protective film MD test specimen, and the 5% strain tensile stress was determined. A test specimen measuring 150 mm in length and 10 mm in width (hereinafter sometimes referred to as the "thermoplastic resin film TD test specimen") was cut from the thermoplastic resin film so that the TD direction of the thermoplastic resin film was the longitudinal direction of the test specimen. A tensile test of the thermoplastic resin film TD test specimen was performed under the same conditions as the tensile test of the protective film MD test specimen, and the 5% strain tensile stress was determined.

[0116] <Peeling of protective film from molded products> A composite film, acting as a paint substitute, was applied to a 0.6 mm thick steel plate coated with zinc alloy, and the composite film and steel plate were heat-pressed together at 260°C. The resulting laminate was cut to a size of 160 mm in length and 160 mm in width. The cut laminate was then subjected to deep drawing at a drawing ratio of 1.3. Specifically, the periphery of the cut laminate was held with a load of 15 tons using a die and plate holder, and the center of the steel plate was pressed at room temperature with a punch at 100 tons. This resulted in a deep-drawn laminate, i.e., a molded product. The protective film on the molded product was visually inspected according to the following criteria to determine whether it had peeled off. Judgment A: The protective film has not been peeled off at all. Judgment B: At least a portion of the protective film has peeled off.

[0117] <Tearing of protective film in molded products> The protective film on the molded product was visually inspected according to the following criteria to determine if it was torn. Rating A: The protective film is not torn at all. Judgment B: At least one part of the protective film is torn.

[0118] <Preparation of hard coat coatings> 150 parts by mass of methyl isobutyl ketone were charged into a four-necked flask equipped with a condenser, stirrer, thermometer, and nitrogen inlet tube, and the mixture was heated while stirring under a nitrogen atmosphere. When the temperature in the flask reached 74°C, this temperature was maintained as the synthesis temperature, and a monomer solution consisting of 3 parts by mass of methyl methacrylate, 82.54 parts by mass of n-butyl methacrylate, 12.85 parts by mass of 4-hydroxybutyl acrylate, 0.61 parts by mass of methacrylic acid, 1 part by mass of Funcryl FA-711MM (manufactured by Hitachi Chemical Co., Ltd., pentamethylpiperidinyl methacrylate), and 0.1 parts by mass of azobisisobutyronitrile was added dropwise to the flask over 2 hours. Starting 1 hour after the end of monomer addition, 0.02 parts by mass of azobisisobutyronitrile were added every hour to continue the reaction until the amount of unreacted monomer in the monomer solution was 1% or less. When the amount of unreacted monomer was reduced to 1% or less, the reaction was terminated by cooling, yielding an acrylic copolymer solution with a solid content of approximately 40% by mass. To this acrylic copolymer solution, 59.9 parts by mass (solid mass) of Duranate "P301-75E" (manufactured by Asahi Kasei Chemicals, a polyisocyanate variant of hexamethylene diisocyanate) was added as a polyisocyanate compound, and then methyl isobutyl ketone was added to bring the solid content to 30% by mass, and the mixture was stirred to obtain a hard coat coating.

[0119] <Making protective film> (Protective film A) Density 0.923g / cm 3 High-pressure low-density polyethylene (LDPE) with an MFR (melt flow rate) of 3.6 and a density of 0.918 g / cm³. 3 Linear low-density polyethylene (LLDPE) with an MFR of 3.8 was blended with LDPE:LLDPE=1:4 by mass ratio, and the raw resins were melt-kneaded at 170°C using an inflation film forming machine to obtain a polyethylene film with a thickness of 47 μm, i.e., protective film A.

[0120] (Protective film B) Density 0.923g / cm 3 High-pressure low-density polyethylene (LDPE) with an MFR of 3.6 and a density of 0.918 g / cm³. 3Linear low-density polyethylene (LLDPE) with an MFR of 3.8 was blended with LDPE:LLDPE=4:1 by mass ratio, and the raw resins were melt-kneaded at 160°C using an inflation film forming machine to obtain a polyethylene film with a thickness of 60 μm, i.e., protective film B.

[0121] (Protective film C) Using an inflation-based film formation machine, the density was 0.923 g / cm³. 3 High-pressure low-density polyethylene (LDPE) with an MFR of 3.6 was melt-kneaded at 150°C to obtain a polyethylene film with a thickness of 60 μm, i.e., protective film C.

[0122] (Protective film D) Polyethylene terephthalate (IV=0.64dL / g) containing 0.05% by mass of bulk silica particles with an average particle size of 2.3 μm was dried at 160°C for 4 hours. In other words, moisture was removed. The polyethylene terephthalate from which moisture had been removed was melted at 280°C in an extruder and then extruded using a die. A sheet was obtained by rapidly cooling the polyethylene terephthalate extruded from the die in a casting drum at 20°C. The sheet was stretched 3.2 times in the MD direction at 90°C. A release layer-forming coating mainly composed of dimethylpolysiloxane resin was applied to one side of the sheet (i.e., uniaxially oriented film) after stretching in the MD direction using a microgravure coater so that the thickness of the release layer (thickness after drying) was 120 nm. Next, the coating film of the release layer-forming coating was dried, and the uniaxial film was stretched 3.3 times in the TD direction at 105°C. The film after stretching in the TD direction was relaxed by 1% in the TD direction while being treated at 210°C in the crystallization zone. This resulted in a biaxially oriented polyethylene terephthalate film with a thickness of 45 μm, i.e., protective film D.

[0123] (Protective film E) Protective film E was obtained using the same method as protective film D, except that the stretching ratio in the MD direction was changed to 3.8 times, the stretching ratio in the TD direction to 4.1 times, and the thickness of the biaxially oriented polyethylene terephthalate film was changed to 38 μm. In this case, the extrusion amount of molten resin (i.e., molten polyethylene terephthalate) was adjusted to change the thickness to 38 μm.

[0124] (Protective film F) Isophthalic acid copolymer polyethylene terephthalate containing 0.05% by mass of bulk silica particles with an average particle size of 2.3 μm (specifically, copolymer polyethylene terephthalate with IV = 0.64 dL / g, where isophthalic acid accounts for 10 mol% of the total dicarboxylic acid component, and 100 mol% of isophthalic acid) was dried at 160°C for 4 hours. In other words, moisture was removed. The isophthalic acid copolymer polyethylene terephthalate from which the moisture was removed was melted at 280°C in an extruder and then extruded using a die. A sheet was obtained by rapidly cooling the isophthalic acid copolymer polyethylene terephthalate extruded from the die in a casting drum at 20°C. The sheet was stretched 3.6 times in the MD direction at 90°C. A release layer-forming coating mainly composed of dimethylpolysiloxane resin was applied to one side of the sheet after MD stretching (i.e., uniaxially oriented film) using a microgravure coater so that the thickness of the release layer (thickness after drying) was 120 nm. Next, the release layer coating was dried, and the uniaxial film was stretched 3.6 times in the TD direction at 105°C. The film after stretching in the TD direction was relaxed by 1% in the TD direction while being treated at 180°C in the crystallization zone. This yielded a biaxially oriented polyethylene terephthalate film with a thickness of 19 μm, i.e., protective film F. The release layer coating used to produce protective film F was the same as the release layer coating used to produce protective film D.

[0125] (Protective film G) Protective film G was obtained using the same method as protective film D, except that the stretching ratio in the MD direction was changed to 3.6 times, the stretching ratio in the TD direction to 3.8 times, and the thickness of the biaxially oriented polyethylene terephthalate film was changed to 31 μm. In this case, the extrusion amount of molten resin (i.e., molten polyethylene terephthalate) was adjusted to change the thickness to 31 μm.

[0126] <Fabrication of thermoplastic resin films> (Thermoplastic resin film X) Polyethylene terephthalate (IV = 0.70 dL / g) containing 0.1% by mass of bulk silica with an average particle size of 1.5 μm was dried and supplied to the first extruder. Isophthalic acid copolymerized polyethylene terephthalate (specifically, copolymerized polyethylene terephthalate in which isophthalic acid accounts for 15 mol% of 100 mol% of total dicarboxylic acid components) (IV = 0.68 dL / g) containing 0.5% by mass of bulk silica with an average particle size of 2.5 μm was dried and supplied to the second extruder. The polyethylene terephthalate was melted in the first extruder and the isophthalic acid copolymerized polyethylene terephthalate was melted in the second extruder. These were co-extruded from adjacent dies at 280°C so that the ratio of the polyethylene terephthalate layer thickness to the isophthalic acid copolymerized polyethylene terephthalate thickness was 4:1, and then rapidly cooled and solidified. The film, after rapid cooling and solidification, i.e., the unstretched laminated film, was stretched 3.4 times in the MD direction at 90°C, 3.6 times in the TD direction at 110°C, and then heat-set at 180°C. This yielded a thermoplastic resin film X with a thickness of 50 μm.

[0127] (Thermoplastic resin film Y) Isophthalic acid copolymerized polyethylene terephthalate (specifically, copolymerized polyethylene terephthalate in which isophthalic acid is 6 mol% out of 100 mol% of total dicarboxylic acid components) (IV = 0.72 dL / g), containing 0.1 mass% of bulk silica with an average particle size of 1.5 μm, and polybutylene terephthalate (IV = 0.92 dL / g) were mixed in a mass ratio of isophthalic acid copolymerized polyethylene terephthalate:polybutylene terephthalate = 60:40. The resulting mixed resin was dried and then supplied to an extruder for melting. The molten mixed resin was extruded from the die and rapidly cooled and solidified. The film after rapid cooling and solidification, i.e., the unstretched film, was stretched 3.4 times in the MD direction at 70°C, stretched 3.6 times in the TD direction at 90°C, and then heat-set at 170°C. This yielded a thermoplastic resin film Y with a thickness of 50 μm.

[0128] <Fabrication of composite films> (Example 1) An epoxy-containing adhesive was coated onto one side of a thermoplastic resin film (specifically, the surface of the polyethylene terephthalate layer in the thermoplastic resin film X), and then heated air was blown onto it to form an easily adhesive layer with a thickness of 10 nm. This resulted in an easily adhesive treated film. While unwinding the easy-adhesion treated film, a paint for forming a colored layer was applied to the easy-adhesion layer of the film using a comma coater. The paint used for forming the colored layer was a solvent-based paint containing an acrylic urethane resin and 10% by mass of aluminum pigment, with 35% by mass of non-volatile components. The coating was performed so that the thickness of the colored layer was 20 μm, and the film was dried in a drying oven at 90°C and then wound up. As the resulting raw material (i.e., the raw material with the colored layer) was unwound, a hard coat coating was applied to the colored layer using a comma coater so that the hard coat layer thickness was 30 μm, and then it was thoroughly dried in a drying oven at 90°C. This yielded a paint substitute film including an easy-adhesion treated film, a colored layer, and a hard coat layer. A protective film (specifically protective film A) was laminated onto the hard coat layer of the paint-alternative film. Thus, a composite film was obtained. Note that the hard coat layer of the composite film was in a semi-cured state, that is, an uncured state.

[0129] <Examples 2 - 3 and Comparative Examples 1 - 7> A composite film was produced in the same manner as in Example 1, except that the combination of the thermoplastic resin film and the protective film was changed.

[0130]

Table 1

[0131] S mt / S mp and S tt / S tp In molded products using a composite film in which both S mt / S mp and S tt / S tp were excessively small, at least a part of the protective film peeled off (see Comparative Examples 1 - 5).

[0132] On the other hand, in molded products using a composite film in which both S mt / S mp and S tt / S tp were not excessively small and not excessively large, neither peeling nor breakage of the protective film occurred (see Examples 1 - 3).

Industrial Applicability

[0133] Since the present invention relates to a composite film, a laminate, and a molded product, the present invention has industrial applicability.

Explanation of Reference Numerals

[0134] 7...Composite film, 8...Paint substitute film, 9...Protective film, 81...Thermoplastic resin film (biaxially oriented polyester film as an example), 82...Adhesive layer, 83...Coloring layer, 84...Surface protective layer, 811...B layer, 812...A layer, 4...Laminate, 5...Metal plate

Claims

1. Paint substitute film, A composite film including a protective film, The aforementioned paint substitute film includes a thermoplastic resin film, a coloring layer, and a surface protective layer. At least the thermoplastic resin film, the colored layer, the surface protective layer, and the protective film are stacked in this order. The aforementioned surface protective layer has curability, S ｍｔ / S ｍｐ The range is 5.0 to 10.0, and S ｍｔ This is the 5% strain tensile stress of the thermoplastic resin film in the MD direction, and S ｍｐ This is the 5% strain tensile stress of the protective film in the MD direction, S ｔｔ / S ｔｐ The range is 5.0 to 10.0, and S ｔｔ This is the 5% strain tensile stress of the thermoplastic resin film in the TD direction, and S ｔｐ This is the 5% strain tensile stress of the protective film in the TD direction. Composite film.

2. The composite film according to claim 1, wherein the thermoplastic resin film is a polyethylene terephthalate film.

3. The composite film according to claim 1, wherein the protective film is a polyethylene film.

4. The composite film according to claim 1, wherein the surface protective layer comprises at least one of a thermosetting resin and a photocurable resin.

5. Further including an adhesive layer, At least the thermoplastic resin film, the adhesive layer, the coloring layer, the surface protective layer, and the protective film are stacked in this order. The composite film according to claim 1.

6. A metal plate and The composite film according to any one of claims 1 to 5 is laminated on the metal plate, Laminated structure.

7. A molded product obtained by press-forming the laminate described in claim 6.

8. The process of heating the metal plate, The process includes pressing the composite film according to any one of claims 1 to 5 onto the heated metal plate, A method for manufacturing laminates.

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