Laminate, molded article, vehicle exterior component, and method for manufacturing laminate

Abstract

A purpose of the present invention is to provide a laminate which makes it possible to reduce or prevent the occurrence of detachment of a coating substitution film from a metal sheet, and which further makes it possible to reduce or prevent deterioration in the appearance of the coating substitution film which may occur due to heat received by the coating substitution film during press-molding of the laminate. Another purpose of the present invention is to provide a molded article. Another purpose of the present invention is to provide a vehicle exterior component. The present invention pertains to a laminate (4) including a metal sheet (5) and a coating substitution film (8) laminated on the metal sheet (5). A biaxially-aligned polyester film (81) of the coating substitution film (8) contains a polyester including an alkylene terephthalate unit. In an X-ray diffraction pattern of the laminate (4), the ratio of an integrated intensity of a diffraction peak indicating the (1-10) plane derived at least from the alkylene terephthalate unit with respect to an integrated intensity of a diffraction peak indicating the (100) plane derived at least from the alkylene terephthalate unit is 0.2-1.0.

Description

Laminate, molded article, vehicle exterior part, and method for manufacturing laminate

[0001] The present invention relates to a laminate, a molded article, a vehicle exterior part, and a method for manufacturing a laminate.

[0002] Automobile exterior parts, such as door panels, front fenders, roofs, back doors, and hoods, are painted. For painting, the paint is generally sprayed onto the metal plate, i.e., spray painting is used.

[0003] However, spray painting places a heavy burden on the environment because the paint used in it contains volatile organic compounds (VOCs).Moreover, because spray painting is done repeatedly, a large space is required for spray painting.

[0004] Instead of painting a metal plate, a method of laminating a paint substitute film onto the metal plate has been proposed (see Patent Document 1). The paint substitute film of Patent Document 1 includes a colored layer, so that the paint substitute film can decorate or protect the metal plate.

[0005] Japanese Patent Application Laid-Open No. 2020-192787

[0006] When manufacturing automotive exterior parts using metal sheets laminated with paint substitute films, the metal sheets to which the paint substitute films are laminated may be press-formed. The heat received by the paint substitute film during press-forming can deteriorate the appearance (i.e., the appearance) of the paint substitute film. After press-forming, the paint substitute film may also peel off from the metal sheet.

[0007] The present invention aims to provide a laminate that can reduce or prevent peeling of a paint substitute film from a metal sheet and that can reduce or prevent deterioration in the appearance (i.e., visual appearance) of the paint substitute film that can be caused by heat received by the paint substitute film when the laminate is press-formed. Another object of the present invention is to provide a molded product obtained by press-forming the laminate. Another object of the present invention is to provide a vehicle exterior part obtained by press-forming the laminate.

[0008] In order to solve this problem, the present invention has the following configuration [1]: [1] A laminate including a metal plate and a paint substitute film laminated to the metal plate, wherein the paint substitute film includes a biaxially oriented polyester film, a colored layer, and a surface protective layer, the biaxially oriented polyester film includes a first layer (hereinafter sometimes referred to as "layer B") and a second layer (hereinafter sometimes referred to as "layer A"), the first layer is located between the second layer and the colored layer, the first layer contains a first polyester including alkylene terephthalate units, the second layer contains a second polyester including alkylene terephthalate units, the melting point of the first layer is higher than the melting point of the second layer, In an X-ray diffraction pattern of the laminate, the ratio of the integrated intensity of a diffraction peak representing a (1-10) plane derived from at least the alkylene terephthalate units of the first polyester and the alkylene terephthalate units of the second polyester to the integrated intensity of a diffraction peak representing a (100) plane derived from at least the alkylene terephthalate units of the first polyester and the alkylene terephthalate units of the second polyester is 0.2 or more and 1.0 or less, and the (1-10) plane is the following crystal plane: Since this crystal plane cannot be entered as text in online procedures with the Japan Patent Office, in this specification this crystal plane is referred to as the "(1-10) plane," which can be entered as text.

[0009] According to [1], since the paint substitute film includes a colored layer, the paint substitute film can decorate or protect the metal plate.

[0010] Furthermore, since the paint substitute film includes a surface protective layer, the colored layer can be protected by the surface protective layer.

[0011] Furthermore, since the melting point of the first layer is higher than that of the second layer, i.e., the melting point of the second layer is lower than that of the first layer, it is possible to lower the lamination temperature (specifically, the thermocompression bonding temperature) compared to when the biaxially oriented polyester film consists of only the first layer.

[0012] In the laminate [1], the ratio (hereinafter sometimes referred to as the "integrated intensity ratio") of the integrated intensity of the diffraction peak representing the (1-10) plane (hereinafter sometimes referred to as the "first integrated intensity") to the integrated intensity of the diffraction peak representing the (100) plane (hereinafter sometimes referred to as the "second integrated intensity") is specified, and the integrated intensity ratio can be regarded as an index of crystallinity. This will be explained using the example of a biaxially oriented polyethylene terephthalate (PET) film. In a biaxially oriented PET film, the (100) plane of the PET crystal structure is a crystal plane containing a benzene ring. The (100) plane is approximately parallel to the plane of the biaxially oriented PET film (which can also be referred to as the "main surface"). On the other hand, the (1-10) plane of the PET crystal structure is a plane tilted relative to the (100) plane, and therefore faces in a variety of directions compared to the (100) plane. Therefore, in the X-ray diffraction pattern of a biaxially oriented PET film, the integrated intensity of the diffraction peak representing the (1-10) plane is less affected by the crystallinity of PET than the integrated intensity of the diffraction peak representing the (100) plane (i.e., the crystallinity of PET). Therefore, the smaller the ratio of the integrated intensity of the diffraction peak representing the (1-10) plane to the integrated intensity of the diffraction peak representing the (100) plane, the higher the crystallinity of PET. Therefore, this ratio can be regarded as an index of crystallinity. This principle also applies to the biaxially oriented polyester film of the laminate [1]. Therefore, the integrated intensity ratio (i.e., the ratio of the first integrated intensity to the second integrated intensity) can be regarded as an index of crystallinity.

[0013] According to the laminate of [1], since the integrated intensity ratio is 1.0 or less, the crystallinity is not excessively low, and therefore the heat resistance of the biaxially oriented polyester film can be improved. Therefore, it is possible to reduce or prevent the occurrence of irregularities on the surface of the biaxially oriented polyester film that may be caused by the heat received by the paint substitute film when the laminate is press-molded. As a result, it is possible to reduce or prevent deterioration of the surface shape of the paint substitute film that may be caused by the heat. Therefore, it is possible to reduce or prevent deterioration of the appearance (i.e., appearance) of the paint substitute film that may be caused by the heat.

[0014] On the other hand, since the integrated intensity ratio is 0.2 or more, the crystallinity is not excessively high, and therefore the adhesive strength with the metal plate is prevented from becoming excessively low, which reduces or prevents the paint substitute film from peeling off from the metal plate, particularly after the laminate is press-molded.

[0015] The present invention preferably has the following configurations [2] to

[13] . [2] The laminate according to [1], wherein the paint substitute film further comprises an adhesive layer, and the adhesive layer is located between the biaxially oriented polyester film and the colored layer. [3] The laminate according to [2], wherein the adhesive layer has a thickness of 10 nm or more and 200 nm or less. [4] The laminate according to any of [1] to [3], wherein the colored layer contains a resin and a colorant. [5] The laminate according to any of [1] to [4], wherein the alkylene terephthalate units of the first polyester comprise ethylene terephthalate units, the alkylene terephthalate units of the second polyester comprise ethylene terephthalate units, the (1-10) plane is a (1-10) plane derived from at least the ethylene terephthalate units of the first polyester and the ethylene terephthalate units of the second polyester, and the (100) plane is a (100) plane derived from at least the ethylene terephthalate units of the first polyester and the ethylene terephthalate units of the second polyester. [6] The laminate according to [5], wherein, when the repeating units of the first polyester are taken as 100 mol%, the ethylene terephthalate units account for 85 mol% or more, and when the repeating units of the second polyester are taken as 100 mol%, the ethylene terephthalate units account for 60 mol% or more. [7] The laminate according to any one of [1] to [6], further comprising a protective film, in which the metal plate, the paint substitute film, and the protective film are stacked in this order. [8] The laminate according to any one of [1] to [7], which is used for producing a vehicle exterior part. [9] A molded product obtained by pressing the laminate according to any one of [1] to [8].

[10] A vehicle exterior part obtained by pressing the laminate according to any one of [1] to [8].

[11] A method for producing a laminate according to any one of [1] to [8], comprising the steps of heating the metal plate and pressing the heated metal plate and the paint substitute film or composite film together, wherein the composite film comprises the paint substitute film and a protective film provided on the surface protective layer of the paint substitute film.

[12] A method for producing a laminate according to

[11] , further comprising the step of starting cooling within 5 seconds after pressing the metal plate and the paint substitute film or composite film together.

[13] A method for producing a laminate according to

[11] or

[12] , wherein the first layer of the paint substitute film or the composite film that is pressed onto the metal plate has a planar orientation coefficient of 0.165 or more and 0.180 or less, and the second layer of the paint substitute film or the composite film that is pressed onto the metal plate has a planar orientation coefficient of 0.100 or more and 0.135 or less.

[0016] The present invention also preferably has the following configurations.

[14] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the above configurations, wherein the metal plate comprises an alloy plate.

[15] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the above configurations, wherein the metal plate comprises a steel plate, an aluminum alloy plate, or a magnesium alloy plate.

[16] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the above configurations, wherein the metal plate comprises a steel plate plated with a zinc alloy.

[17] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the above configurations, wherein the biaxially oriented polyester film has a thickness of 10 μm or more, or 15 μm or more.

[18] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the above configurations, wherein the biaxially oriented polyester film has a thickness of 20 μm or more, or 30 μm or more.

[19] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the above configurations, wherein the biaxially oriented polyester film has a thickness of 200 μm or less, or 150 μm or less.

[20] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the above configurations, wherein the biaxially oriented polyester film has a thickness of 100 μm or less, or 75 μm or less.

[21] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the above configurations, wherein the sum of the heat shrinkage in the machine direction and the heat shrinkage in the width direction when the biaxially oriented polyester film is heat-treated at 150°C for 15 minutes is 5.0% or less or 4.8% or less.

[22] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the above configurations, wherein the sum of the heat shrinkage in the machine direction and the heat shrinkage in the width direction is 4.5% or less or 4.0% or less.

[23] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the above configurations, wherein the sum of the heat shrinkage rate in the machine direction and the heat shrinkage rate in the width direction is 1.0% or more or 2.0% or more.

[24] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the above configurations, wherein the sum of the heat shrinkage rate in the machine direction and the heat shrinkage rate in the width direction is 3.0% or more.

[25] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the above configurations, wherein the difference between the melting point of the first layer and the melting point of the second layer is 20°C or more or 25°C or more.

[26] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the above configurations, wherein the difference between the melting point of the first layer and the melting point of the second layer is 28°C or more or 30°C or more.

[27] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the above configurations, wherein the difference between the melting point of the first layer and the melting point of the second layer is 70°C or less or 60°C or less.

[28] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the above configurations, wherein the difference between the melting point of the first layer and the melting point of the second layer is 50°C or less.

[29] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the above configurations, wherein the ratio of the thickness of the first layer to the thickness of the second layer (i.e., thickness of the first layer / thickness of the second layer) is 1.5 or more or 2.0 or more.

[30] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the above configurations, wherein the ratio (i.e., thickness of the first layer / thickness of the second layer) is 10 or less or 8 or less.

[31] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the above configurations, wherein the ratio (i.e., thickness of the first layer / thickness of the second layer) is 6 or less.

[32] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the above configurations, wherein the thickness of the first layer is 20 μm or more or 25 μm or more.

[33] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the above configurations, wherein the thickness of the first layer is 30 μm or more.

[34] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the preceding configurations, wherein the thickness of the first layer is 150 μm or less or 100 μm or less.

[35] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the preceding configurations, wherein the thickness of the first layer is 75 μm or less or 50 μm or less.

[36] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the preceding configurations, wherein the melting point of the first layer is 250°C or more or 252°C or more.

[37] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the preceding configurations, wherein the melting point of the first layer is 253°C or higher.

[38] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the preceding configurations, wherein the melting point of the first layer is 260°C or lower or 258°C or lower.

[39] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the preceding configurations, wherein the planar orientation coefficient of the first layer is 0.165 or higher or 0.168 or higher.

[40] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the preceding configurations, wherein the planar orientation coefficient of the first layer is 0.170 or higher.

[41] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the preceding configurations, wherein the planar orientation coefficient of the first layer is 0.180 or lower or 0.178 or lower.

[42] The laminate, molded article, vehicle exterior part, or method for producing a laminate according to any of the above configurations, wherein the ethylene terephthalate units account for 85 mol% or more or 90 mol% or more of the repeating units of the first polyester, taken as 100 mol%.

[43] The laminate, molded article, vehicle exterior part, or method for producing a laminate according to any of the above configurations, wherein the ethylene terephthalate units account for 95 mol% or more or 97 mol% or more of the repeating units of the first polyester, taken as 100 mol%.

[44] The laminate, molded article, vehicle exterior part, or method for producing a laminate according to any of the above configurations, wherein the first polyester is a crystalline polyester.

[45] The laminate, molded article, vehicle exterior part, or method for producing a laminate according to any of the above configurations, wherein the first polyester is polyethylene terephthalate.

[46] The laminate, molded article, vehicle exterior part, or method for producing a laminate according to any of the above configurations, wherein the polyethylene terephthalate is homopolyethylene terephthalate or copolymer polyethylene terephthalate.

[47] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the preceding aspects, wherein the first layer contains inert particles.

[48] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the preceding aspects, wherein the first layer contains silica particles.

[49] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the preceding configurations, wherein the thickness of the second layer is 5 μm or more or 10 μm or more.

[50] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the preceding configurations, wherein the thickness of the second layer is 30 μm or less or 25 μm or less.

[51] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the preceding configurations, wherein the thickness of the second layer is 20 μm or less or 15 μm or less.

[52] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the preceding configurations, wherein the planar orientation coefficient of the second layer is 0.135 or less or 0.132 or less.

[53] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the preceding configurations, wherein the planar orientation coefficient of the second layer is 0.130 or less.

[54] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the above configurations, wherein the second layer has a planar orientation coefficient of 0.100 or more or 0.110 or more.

[55] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the above configurations, wherein the second layer has a planar orientation coefficient of 0.112 or more.

[56] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the above configurations, wherein the ethylene terephthalate units account for 60 mol % or more or 70 mol % or more when the repeating units of the second polyester are taken as 100 mol %.

[57] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the above configurations, wherein the ethylene terephthalate units account for 80 mol % or more or 82 mol % or more when the repeating units of the second polyester are taken as 100 mol %.

[58] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the above configurations, wherein the ethylene terephthalate units account for 96 mol % or less or 94 mol % or less when the repeating units of the second polyester are taken as 100 mol %.

[59] The laminate, molded article, vehicle exterior part, or laminate manufacturing method according to any of the above configurations, wherein the ethylene terephthalate units account for 92 mol % or less or 90 mol % or less when the repeating units of the second polyester are taken as 100 mol %.

[60] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the above configurations, wherein the second polyester is a crystalline polyester.

[61] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the above configurations, wherein the second polyester is polyethylene terephthalate.

[62] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the above configurations, wherein the polyethylene terephthalate of the second polyester is copolymerized polyethylene terephthalate.

[63] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the above configurations, wherein the integrated intensity ratio is 0.9 or less or 0.8 or less.

[64] The laminate, molded article, vehicle exterior part, or method for manufacturing a laminate according to any of the above configurations, wherein the integrated intensity ratio is 0.3 or more or 0.4 or more.

[65] The method for manufacturing a laminate according to

[11] , further comprising a step of starting cooling within 3 seconds or within 2 seconds after pressing the metal plate and the paint substitute film or the composite film together.

[66] A method for manufacturing a laminate according to any of the above aspects, wherein the metal plate to which the paint substitute film or the composite film is pressure-bonded is cooled in water at 60° C. or below or 45° C.

[67] A method for manufacturing a laminate according to any of the above aspects, wherein the metal plate to which the paint substitute film or the composite film is pressure-bonded is cooled in water at 35° C. or below or 30° C.

[68] A method for manufacturing a laminate according to any of the above aspects, wherein the metal plate to which the paint substitute film or the composite film is pressure-bonded is immersed in a water tank to cool.

[0017] According to the present invention, it is possible to provide a laminate that can reduce or prevent peeling of the paint substitute film from the metal plate and that can reduce or prevent deterioration in the appearance (i.e., appearance) of the paint substitute film that may occur due to heat received by the paint substitute film when the laminate is press-molded. According to the present invention, it is also possible to provide a molded product obtained by press-forming the laminate. The present invention can also provide a vehicle exterior part obtained by press-forming the laminate.

[0018] 1 is a schematic cross-sectional view of a laminate according to this embodiment. 2 is an example of an X-ray diffraction pattern of the laminate according to this embodiment. Here, the horizontal axis represents the 2θ angle, and the vertical axis represents the diffracted X-ray intensity. In this example, the diffraction peak near 2θ=23° is a diffraction peak representing the (1-10) plane of polyethylene terephthalate, and the diffraction peak near 2θ=26° is a diffraction peak representing the (100) plane of polyethylene terephthalate.

[0019] Hereinafter, embodiments of the present invention will be described in detail.

[0020] 1. Laminate As shown in FIG. 1, the laminate 4 includes a metal plate 5 and a composite film 7 laminated to the metal plate 5 .

[0021] That is, the laminate 4 includes a metal plate 5, a paint substitute film 8 laminated to the metal plate 5, and further includes a protective film 9. In the laminate 4, the metal plate 5, the paint substitute film 8, and the protective film 9 are stacked in this order.

[0022] <1.1. Metal Sheet> Examples of the metal sheet 5 include alloy sheets such as steel sheets, aluminum alloy sheets, and magnesium alloy sheets. Among these, steel sheets are preferred. Examples of the steel sheets include stainless steel sheets. These may be pretreated with zinc alloy plating or chrome plating. In other words, the steel sheets may be surface-treated steel sheets. Examples of the surface-treated steel sheets include tin-free steel sheets and tinplate. In particular, when the laminate 4 is used to manufacture vehicle exterior parts, the metal sheet 5 is preferably a steel sheet plated with a zinc alloy. The zinc alloy plating can improve rust resistance.

[0023] 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. Among these, for the reason that formability is good, 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. When the metal plate 5 is a zinc alloy-plated steel plate, the thickness of the metal plate 5 is preferably 0.4 mm or more and 0.8 mm or less. When 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.

[0024] 1.2 Composite Film 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 the paint substitute film 8.

[0025] <1.2.1. Paint Substitute Film> The paint substitute film 8 includes a biaxially oriented polyester film 81, an adhesive layer 82, a colored layer 83, and a surface protective layer (hereinafter, sometimes referred to as a "hard coat layer") 84. In the paint substitute film 8, the biaxially oriented polyester film 81, the adhesive layer 82, the colored layer 83, and the surface protective layer 84 are stacked in this order.

[0026] <1.2.1.1. Biaxially oriented polyester film> The biaxially oriented polyester film 81 is provided on the metal plate 5. Specifically, the layer A 812 of the biaxially oriented polyester film 81 is provided on the metal plate 5.

[0027] 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. When the thickness is 10 μm or more, film formation is easy, and functional layers such as the colored layer 83 and the surface protective layer 84 are also easily formed. In addition, the paint substitute film 8 or the composite film 7 is easy to handle when laminated to the metal plate 5. 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. When the thickness is 200 μm or less, the load required for press molding can be prevented from becoming excessively large when the laminate 4 is press molded.

[0028] When the biaxially oriented polyester film 81 is heat-treated at 150°C for 15 minutes, the sum of the heat shrinkage in the machine direction and the heat shrinkage in the width direction is preferably 5.0% or less, more preferably 4.8% or less. The smaller this sum, the more likely it is that the biaxially oriented polyester film 81 will be reduced by the heat it receives during lamination (specifically, during thermocompression bonding), thereby suppressing a decrease in adhesive strength with the metal plate that may result from the heat shrinkage. The smaller this sum, the more likely it is that the dimensional change in the paint substitute film 8 caused by heat generated by shear during press-molding of the laminate 4 will be reduced. In other words, the paint substitute film 8 will have excellent dimensional stability. This sum may be, for example, 4.5% or less, 4.2% or less, or 4.0% or less. On the other hand, this sum may be 1.0% or more, 2.0% or more, or 3.0% or more. This sum can be controlled by the stretching conditions and heat-setting conditions. The heat shrinkage rate of the biaxially oriented polyester film 81 can be calculated by the following formula: Heat shrinkage rate (%) = {(L ０ -L) / L ０}×100 where L is the gauge length after heat treatment (specifically, heat treatment at 150° C. for 15 minutes), and L ０ is the gauge length before heat treatment (specifically, heat treatment at 150° C. for 15 minutes).

[0029] The biaxially oriented polyester film 81 includes a B layer (i.e., a first layer) 811 and an A layer (i.e., a second layer) 812. The B layer 811 is located between the A layer 812 and the colored layer 83.

[0030] The melting point of the B layer 811 (hereinafter sometimes referred to as "TmB") is higher than the melting point of the A layer 812 (hereinafter sometimes referred to as "TmA"), i.e., the melting point of the A layer 812 is lower than the melting point of the B layer 811. This makes it possible to lower the lamination temperature (specifically, the thermocompression bonding temperature) compared to when the biaxially oriented polyester film 81 is made of only the B layer 811.

[0031] The difference between the melting point of the B layer 811 and the A layer 812 is preferably 20°C or more, more preferably 25°C or more, even more preferably 28°C or more, and even more preferably 30°C or more. A temperature of 20°C or more can reduce deterioration of the surface shape of the biaxially oriented polyester film 81 that can be caused by heat received by the paint substitute film 8 during lamination (specifically, during thermocompression bonding), and can also reduce the viscosity of the A layer 812 during lamination (specifically, during thermocompression bonding). On the other hand, the difference between the melting point of the B layer 811 and the melting point of the A layer 812 is preferably 70°C or less, more preferably 60°C or less, and even more preferably 50°C or less. A temperature of 70°C or less provides good handling properties during film formation.

[0032] The ratio of the thickness of the B layer 811 to the thickness of the A layer 812 (i.e., thickness of the B layer 811 / thickness of the A layer 812) is preferably 1.5 or more, and preferably 2.0 or more. A ratio of 1.5 or more can reduce deterioration in the appearance of the paint substitute film 8 that may be caused by heat received by the paint substitute film 8 during lamination (specifically, during thermocompression bonding). In addition, deterioration in the appearance of the paint substitute film 8 that may be caused by heat received by the paint substitute film 8 when the laminate 4 is press-molded can be further reduced or prevented. On the other hand, the ratio of the thickness of the B layer 811 to the thickness of the A layer 812 (i.e., thickness of the B layer 811 / thickness of the A layer 812) is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less.

[0033] The thickness of the B layer 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 can reduce deterioration of the surface shape of the biaxially oriented polyester film 81, which may occur due to heat received by the paint substitute film 8 during lamination (specifically, during thermocompression bonding). In addition, deterioration of the appearance of the paint substitute film 8, which may occur due to heat received by the paint substitute film 8 when the laminate 4 is press-molded, can be further reduced or prevented. The thickness of the B layer 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.

[0034] The melting point of the B layer 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 the B layer 811 may be 260° C. or lower, or 258° C. or lower.

[0035] The plane orientation coefficient of the B layer 811 is preferably 0.165 or more, more preferably 0.168 or more, and even more preferably 0.170 or more. This is because the larger the plane orientation coefficient of the B layer 811, the more likely it is that wrinkles and bubbles will be generated in the paint substitute film 8 due to the heat received by the paint substitute film 8 during lamination (specifically, during thermocompression bonding). In addition, the larger the plane orientation coefficient of the B layer 811, the more likely it is that the biaxially oriented polyester film 81 will be able to conform to the springback that occurs when the laminate 4 is press-molded. On the other hand, the plane orientation coefficient of the B layer 811 is preferably 0.180 or less, and more preferably 0.178 or less.

[0036] The B layer 811 contains a first polyester, i.e., a first polyester resin. The intrinsic viscosity of the first polyester is preferably 0.60 or more. When the intrinsic viscosity is 0.60 or more, the generation of heat-degraded products derived from low-molecular-weight components can be reduced. On the other hand, the intrinsic viscosity of the first polyester is preferably less than 0.95.

[0037] The first polyester comprises repeating units that include alkylene terephthalate units, i.e., the repeating units of the first polyester comprise alkylene terephthalate units.

[0038] Examples of the alkylene terephthalate unit include an ethylene terephthalate unit, a trimethylene terephthalate unit, and a polybutylene terephthalate unit, with the ethylene terephthalate unit being preferred.

[0039] When the repeating units of the first polyester are taken as 100 mol %, the alkylene terephthalate units are preferably 85 mol % or more, more preferably 90 mol % or more, even more preferably 95 mol % or more, and even more preferably 97 mol % or more.

[0040] When the repeating units of the first polyester are taken as 100 mol %, the ethylene terephthalate units are preferably 85 mol % or more, more preferably 90 mol % or more, even more preferably 95 mol % or more, and even more preferably 97 mol % or more.

[0041] The repeating units of the first polyester may contain other units. Examples of such other units include alkylene isophthalate units and alkylene naphthalate units. Examples of alkylene isophthalate units include ethylene isophthalate units, trimethylene isophthalate units, and polybutylene isophthalate units. Examples of alkylene naphthalate units include ethylene naphthalate units, trimethylene naphthalate units, and polybutylene naphthalate units. However, it is preferable that the repeating units of the first polyester do not contain alkylene isophthalate units. It is preferable that the repeating units of the first polyester do not contain alkylene naphthalate units.

[0042] The first polyester is preferably a crystalline polyester. When the first polyester is a crystalline polyester, stretching unevenness of the paint substitute film 8, which may occur when the laminate 4 is press-molded, can be reduced. This will be explained below. When the laminate 4 is press-molded, the paint substitute film 8 is partially stretched by the press molding. If the B layer 811 of the biaxially oriented polyester film 81 contains a crystalline polyester, crystallization of the crystalline polyester can be more advanced in the most stretched portion (i.e., the maximum deformation portion) than in its surroundings (i.e., the surroundings of the maximum deformation portion). Therefore, at the beginning of press molding, the paint substitute film 8 is more likely to stretch in the maximum deformation portion, but as press molding progresses, the maximum deformation portion itself becomes less stretchable. As a result, the surroundings (i.e., the surroundings of the maximum deformation portion) stretch. Therefore, the thickness of the maximum deformation portion can be prevented from becoming excessively thin. Therefore, stretching unevenness of the paint substitute film 8 can be reduced. Crystalline polyester refers to a polyester in which an endothermic peak of 0.05 J / g or more associated with crystalline melting appears in a differential scanning calorimetry (DSC) curve at a temperature higher than the temperature at which a baseline shift corresponding to the glass transition point occurs. In the differential scanning calorimetry to obtain a DSC curve, a sample is scraped from Layer B 811, and 10 mg of the sample is heated to 290°C at 20°C / min, held 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 the differential scanning calorimetry.

[0043] The first polyester is preferably polyethylene terephthalate. Examples of polyethylene terephthalate include homopolyethylene terephthalate and copolymerized polyethylene terephthalate. Among these, homopolyethylene terephthalate is preferred. Homopolyethylene terephthalate may contain a diethylene glycol component, which may be a by-product during its production. On the other hand, examples of copolymerization components, particularly dicarboxylic acids, for obtaining copolymerized polyethylene terephthalate 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 may be used. Examples of copolymerization components, particularly diols, for obtaining copolymerized polyethylene terephthalate include aliphatic diols such as trimethylene glycol (propanediol), butanediol, and hexanediol; and alicyclic diols such as cyclohexanedimethanol. One or more of these may be used. Of these, isophthalic acid and sebacic acid are preferred, and isophthalic acid is more preferred.

[0044] 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 taken as 100% by mass. The content of the first polyester may be, for example, 80% by mass or more, 90% by mass or more, or 95% by mass or more, when the B layer 811 is taken as 100% by mass. On the other hand, the content of the first polyester may be, for example, 100% by mass, or 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 taken as 100% by mass.

[0045] The B layer 811 may contain additives. Examples of additives include color pigments, fluorescent whitening agents, inert particles, antioxidants, heat stabilizers, UV absorbers, and antistatic agents. Examples of color pigments include inorganic pigments and organic pigments. Among these, inorganic pigments are preferred. Examples of inorganic pigments include alumina, titanium dioxide, calcium carbonate, and barium sulfate. Among these, titanium dioxide is preferred when imparting hiding power to the B layer 811. The content of the color pigment may be 2% by mass or more, 4% by mass or more, or 10% by mass or more, based on 100% by mass of the B layer 811. On the other hand, the content of the color pigment may be 50% by mass or less, 40% by mass or less, or 35% by mass or less, based on 100% by mass of the B layer 811. The fluorescent whitening agent can improve whiteness.

[0046] The inert particles can improve the handleability, specifically the slipperiness, of the biaxially oriented polyester film 81. Examples of inert particles include organic materials such as polymers or copolymers of monomers selected from polystyrene, polymethyl ester polyacrylate, polyethyl ester polyacrylate, polymethyl ester polymethacrylate, polyethyl ester polymethacrylate, and divinylbenzene, polytetrafluoroethylene, polyacrylonitrile, benzoguanamine, and silicone. Inorganic materials such as silica, kaolin, talc, and graphite are also preferred. Among these, inorganic materials are preferred, with silica, i.e., silica particles, being more preferred. The particle size of the inert particles is preferably 0.1 μm to 10 μm. The content of the inert particles is preferably 0.002% to 0.5% by mass, based on 100% by mass of the B layer 811.

[0047] The A layer 812 bonds the metal plate 5 and the B layer 811. The A layer 812 is located between the metal plate 5 and the B layer 811.

[0048] The thickness of the A layer 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 in any irregularities that may exist on the metal plate 5, thereby improving the adhesive strength with the metal plate 5. The thickness of the A layer 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.

[0049] The melting point of the A layer 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 the A layer 812 is preferably 250° C. or lower, more preferably 240° C. or lower, and even more preferably 230° C. or lower.

[0050] The plane orientation coefficient of the A layer 812 is preferably 0.135 or less, more preferably 0.132 or less, and even more preferably 0.130 or less. When it is 0.135 or less, the adhesive strength with the metal plate 5 can be improved. On the other hand, the plane orientation coefficient of the A layer 812 is preferably 0.100 or more, more preferably 0.110 or more, and even more preferably 0.112 or more.

[0051] The A layer 812 contains a second polyester, i.e., a second polyester resin. The intrinsic viscosity of the second polyester is preferably 0.60 or more. On the other hand, the intrinsic viscosity of the first polyester is preferably less than 0.95. If the intrinsic viscosity is less than 0.95, it is possible to reduce the viscosity of the A layer 812 during lamination (specifically, during thermocompression bonding), thereby improving the adhesive strength with the metal plate 5.

[0052] The second polyester comprises repeating units that include alkylene terephthalate units, i.e., the repeating units of the second polyester comprise alkylene terephthalate units.

[0053] Examples of the alkylene terephthalate unit include an ethylene terephthalate unit, a trimethylene terephthalate unit, and a polybutylene terephthalate unit, with the ethylene terephthalate unit being preferred.

[0054] When the repeating units of the second polyester are taken as 100 mol%, the alkylene terephthalate units are preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and still more preferably 82 mol% or more. When the repeating units of the second polyester are taken as 100 mol%, the alkylene terephthalate units are preferably 96 mol% or less, more preferably 94 mol% or less, even more preferably 92 mol% or less, and still more preferably 90 mol% or less.

[0055] When the repeating units of the second polyester are taken as 100 mol%, the ethylene terephthalate units are preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and still more preferably 82 mol% or more. When the repeating units of the second polyester are taken as 100 mol%, the ethylene terephthalate units are preferably 96 mol% or less, more preferably 94 mol% or less, even more preferably 92 mol% or less, and still more preferably 90 mol% or less.

[0056] It is preferable that the repeating units of the second polyester contain other units. Examples of such other units include alkylene isophthalate units and alkylene naphthalate units. Examples of alkylene isophthalate units include ethylene isophthalate units, trimethylene isophthalate units, and polybutylene isophthalate units. Examples of alkylene naphthalate units include ethylene naphthalate units, trimethylene naphthalate units, and polybutylene naphthalate units. In particular, it is preferable that the repeating units of the second polyester contain alkylene isophthalate units. When the repeating units of the second polyester are taken as 100 mol%, the alkylene isophthalate units are preferably 4 mol% or more, more preferably 6 mol% or more, even more preferably 8 mol% or more, and even more preferably 10 mol% or more. When the repeating units of the second polyester are taken as 100 mol%, the alkylene isophthalate units are preferably 40 mol% or less, more preferably 30 mol% or less, even more preferably 20 mol% or less, and even more preferably 18 mol% or less. The repeating units of the first polyester preferably do not contain alkylene naphthalate units.

[0057] The second polyester is preferably a crystalline polyester. Crystalline polyester refers to a polyester in which, in a differential scanning calorimetry (DSC) curve, an endothermic peak of 0.05 J / g or more associated with crystalline melting appears at a temperature higher than the temperature at which a baseline shift corresponding to the glass transition point occurs. In differential scanning calorimetry to obtain a DSC curve, a sample is scraped from Layer A 812, and 10 mg of the sample is heated to 290°C at 20°C / min, held isothermally for 3 minutes, rapidly cooled at 200°C / min, and heated to 290°C at 10°C / min. A DSC-60 type differential scanning calorimeter is used for the differential scanning calorimetry.

[0058] The second polyester is preferably a copolymerized polyethylene terephthalate. The description of the copolymerized polyethylene terephthalate in the second polyester overlaps with the description of the copolymerized polyethylene terephthalate in the first polyester, so it will be omitted. Therefore, the description of the copolymerized polyethylene terephthalate in the first polyester can also be used as a description of the copolymerized polyethylene terephthalate in the second polyester.

[0059] 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, relative to 100% by mass of the A layer 812. 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, relative to 100% by mass of the A layer 812.

[0060] The A layer 812 may contain additives such as color pigments, fluorescent whitening agents, inert particles, antioxidants, heat stabilizers, ultraviolet absorbers, and antistatic agents.

[0061] Biaxially oriented polyester film 81 can be produced by the following procedure: preparing an unstretched polyester film, and then biaxially stretching the unstretched polyester film. For example, biaxially oriented polyester film 81 can be produced by feeding a molding material for forming layer B 811 (i.e., a polyester composition containing a first polyester) into a first extruder and a molding material for forming layer A 812 (specifically, a polyester composition containing a second polyester) into a second extruder, then introducing the molding material from the first extruder into a feed block, and then introducing the molding material from the second extruder into the feed block, laminating these molding materials in the feed block, melt-extruding an unstretched polyester film (hereinafter sometimes referred to as a “sheet”) from a die, solidifying the unstretched polyester film on a cooling drum, biaxially stretching the unstretched polyester film, and heat-setting the unstretched polyester film. Alternatively, the film can be produced by the following procedure: feeding the raw materials for forming layer B 811 into a first extruder and the raw materials for forming layer A 812 into a second extruder; then introducing the molding materials from the first extruder into a multi-manifold die; then introducing the molding materials from the second extruder into the multi-manifold die; laminating these molding materials in the multi-manifold die; then melt-extruding an unstretched polyester film from the multi-manifold die; then solidifying the unstretched polyester film on a cooling drum; biaxially stretching the unstretched polyester film; and heat-setting the unstretched polyester film. The biaxial stretching may be simultaneous longitudinal and transverse biaxial stretching or sequential biaxial stretching. Of these, sequential biaxial stretching is preferred. In the sequential biaxial stretching, for example, it is preferable to stretch a sheet that has passed through a cooling roll in the machine direction (hereinafter referred to as "MD"), and then stretch the sheet after stretching in the MD direction in the transverse direction (hereinafter referred to as "TD"). Note that the sheet may be surface-treated between the first stretching (e.g., stretching in the machine direction) and the second stretching (e.g., stretching in the width direction). For example, an adhesive layer 82 may be formed between the first stretching and the second stretching.

[0062] With regard to extrusion, it is preferable that the molding material for forming layer B 811, i.e., the polyester composition containing the first polyester, is thoroughly dried before being supplied to the first extruder and melted at a temperature of from the melting point of the first polyester to (melting point + 50)° C. In contrast, it is preferable that the molding material for forming layer A 812, i.e., the polyester composition containing the second polyester, is thoroughly dried before being supplied to the second extruder and melted at a temperature of from the melting point of the second polyester to (melting point + 50)° C. 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.

[0063] When the biaxial stretching is sequential biaxial stretching, the unstretched polyester film can be heated and stretched in the machine direction. Examples of methods for heating the unstretched polyester film include roll heating and infrared heating. The machine direction stretching temperature is preferably 70°C or higher, more preferably 80°C or higher. At 70°C or higher, the occurrence of breakage can be reduced. On the other hand, the machine direction stretching temperature is preferably 110°C or lower, more preferably 100°C or lower. At 110°C or lower, excessively low orientation can be avoided.

[0064] The stretching ratio in the machine direction is preferably 3.0 times or more, and more preferably 3.5 times or more. At 3.0 times or more, excessively low orientation can be avoided. In addition, excessive thickness unevenness can be reduced or avoided, and excessive slack that may occur when the biaxially oriented polyester film 81 is wound into a roll can be reduced or avoided. On the other hand, the stretching ratio in the machine direction is preferably 5.0 times or less, more preferably 4.5 times or less, and even more preferably 4.0 times or less. At 5.0 times or less, the effect of improving thickness unevenness due to stretching can be effectively achieved. One example of a method for stretching in the machine direction is a method in which a heated unstretched polyester film is stretched by using a speed difference between rolls.

[0065] The polyester film after stretching in the machine direction can be stretched in the width direction. The stretching temperature in the width direction is preferably 90°C or higher. If it is 90°C or higher, the occurrence of breakage can be reduced. On the other hand, the stretching temperature in the width direction is preferably 130°C or lower. If it is 130°C or lower, it is possible to avoid excessively low orientation.

[0066] The stretching ratio in the width direction is preferably 3.0 times or more, more preferably 3.5 times or more. At 3.0 times or more, excessively low orientation can be avoided. In addition, excessive thickness unevenness can be reduced or avoided, and excessive slack that may occur when the biaxially oriented polyester film 81 is wound into a roll can be reduced or avoided. On the other hand, the stretching ratio in the width direction is preferably 5.0 times or less, more preferably 4.5 times or less. At 5.0 times or less, the effect of improving thickness unevenness due to stretching can be effectively enjoyed.

[0067] After biaxial stretching, a heat setting treatment is preferably performed. An example of the heat setting temperature is 150°C or higher and 230°C or lower. The heat setting temperature can be set depending on the type of the first polyester and the type of the second polyester. When the first polyester is polyethylene terephthalate and the second polyester is copolymerized polyethylene terephthalate, the heat setting temperature is preferably 225°C or lower, more preferably 222°C or lower, and even more preferably 220°C or lower. A temperature of 225°C or lower can prevent the crystallinity of the biaxially oriented polyester film 81 before lamination from becoming excessively high, thereby preventing excessive relaxation of the degree of planar orientation. On the other hand, the heat setting temperature is preferably 205°C or higher, more preferably 210°C or higher, and even more preferably 213°C or higher. The heat setting temperature may be 215°C or higher. A temperature of 205°C or higher can prevent the crystallinity of the biaxially oriented polyester film 81 before lamination from becoming excessively low.

[0068] It is preferable to carry out a heat relaxation treatment together with or separately from the heat setting treatment. In the heat relaxation treatment, it is preferable to relax in at least one of the machine direction (i.e., MD direction) and the width direction (i.e., TD direction). In particular, relaxation in the width direction is preferable. When relaxing in the width direction, the relaxation rate in the width direction is preferably 3% or more, more preferably 4% or more. On the other hand, the relaxation rate in the width direction is preferably 8% or less, more preferably 7% or less.

[0069] <1.2.1.2. 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 in interfacial energy between layers, and interfacial mixing between layers. The adhesive layer 82 can also be referred to as an easy-adhesion layer 82.

[0070] From the viewpoint of adhesiveness, the thickness of the adhesive layer 82 is preferably 10 nm or more, more preferably 15 nm or more, even more preferably 20 nm or more, and still more preferably 40 nm or more. On the other hand, from the viewpoint of thickness unevenness and adhesiveness, the thickness of the adhesive layer 82 is preferably 200 nm or less, more preferably 180 nm, even more preferably 150 nm, and still more preferably 120 nm or less.

[0071] 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 resins can be used. Acrylic resins and polyester resins are particularly preferred. Considering that heat is generated by shear during press molding of the laminate 4, and the temperature of the laminate 4 may reach approximately 150°C, the glass transition temperature of the resin is preferably 150°C or lower. Incidentally, it is preferable that the adhesive layer 82 does not contain a polyester containing an alkylene terephthalate unit.

[0072] The resin preferably has at least one functional group selected from the group consisting of an epoxy group, an oxazoline group, a silanol group, and an isocyanate group. Among these, the epoxy group and the oxazoline group are preferred as the functional group because they can further improve adhesion to the B layer 811.

[0073] The adhesive layer 82 can be formed by any method on the biaxially oriented polyester film 81. For example, the adhesive layer 82 may be formed by in-line coating, in which coating is performed during the production of the biaxially oriented polyester film 81. The adhesive layer 82 may also be formed by off-line coating, in which the biaxially oriented polyester film 81 is produced, wound into a roll, and then unwound and coated.

[0074] 1.2.1.3. Coloring Layer The coloring layer 83 is located between the adhesive layer 82 and the surface protective layer 84. The coloring layer 83 is provided on the adhesive layer 82. The coloring layer 83 can decorate or protect the metal plate 5.

[0075] 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 have a single layer structure or a multi-layer structure.

[0076] The colored layer 83 contains a colorant. Examples of colorants include pigments and dyes. Examples of pigments and dyes include carbon black (ink), iron black, titanium white, antimony white, yellow lead, titanium yellow, red iron oxide, cadmium red, ultramarine blue, cobalt blue, quinacridone red, isoindolinone yellow, phthalocyanine blue, aluminum, brass, titanium dioxide, and pearlescent pigments. As described above, the colored layer 83 may have a single-layer structure or a multi-layer structure. For example, when the colored layer 83 has a two-layer structure, it may be preferable for one of the two layers to contain a luster pigment. For example, when the colored layer 83 has a two-layer structure, it may be preferable for the layer closer to the biaxially oriented polyester film 81 to contain an aluminum pigment and the layer closer to the surface protective layer 84 to contain a pigment.

[0077] The content of the colorant is preferably 0.5% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more, based on 100% by mass of the colored layer 83. On the other hand, the content of the colorant is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less, based on 100% by mass of the colored layer 83.

[0078] It is preferable that the colored layer 83 contains a resin (hereinafter, sometimes referred to as a "binder resin"). Since 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-molded. Examples of binder resins include acrylic resin, urethane resin, polyester resin, and PVDF (polyvinylidene fluoride). One or more of these can be used. Of these, acrylic resin is preferred. It is preferable that the colored layer 83 does not contain a polyester containing an alkylene terephthalate unit.

[0079] The colored layer 83 can be formed on the adhesive layer 82 by any method. Coating is preferred because the colored layer 83 can be easily formed.

[0080] <1.2.1.4. Surface Protective Layer> The surface protective layer 84 is provided on the colored layer 83. The surface protective layer 84 can reduce scratches that may occur on the colored layer 83 and the biaxially oriented polyester film 81 (i.e., can improve scratch resistance). In addition, the surface protective layer 84 can sometimes improve adhesion to the protective film 9. The surface protective layer 84 is preferably transparent. The surface protective layer 84 is preferably weather resistant. The surface protective layer 84 may be glossy.

[0081] The thickness of the surface protective 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 a thicker surface protective layer 84 can reduce scratches that may occur on the colored layer 83 and the biaxially oriented polyester film 81 (i.e., can improve scratch resistance) and can also improve chemical resistance. On the other hand, the thickness of the surface protective 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 a thinner surface protective layer 84 is more economical. The surface protective layer 84 may have a single-layer structure or a multi-layer structure.

[0082] It is preferable that the surface protective layer 84 contains at least one of a thermosetting resin and a photocurable resin. In other words, it is preferable that the surface protective layer 84 has thermosetting or photocurable properties. Of these, thermosetting is preferable. In other words, it is preferable that the surface protective layer 84 contains a thermosetting resin. This is because the heat generated by shear when the laminate 4 is press-molded can promote thermosetting. Examples of thermosetting resins include acrylic resin, melamine resin, and urethane resin. Of these, acrylic resin is preferable. One or more of these can be used. It is preferable that the surface protective layer 84 does not contain a polyester containing an alkylene terephthalate unit. It is preferable that the surface protective layer 84 contains a crosslinking agent. The surface protective layer 84 may contain other additives.

[0083] The degree of curing of the surface protective layer 84 may be, for example, fully cured or incompletely cured. Here, fully cured means a state in which curing has been completed. On the other hand, incompletely cured means a state in which curing has not been completed. In particular, incompletely cured is preferred. This is because the surface protective layer 84 can effectively follow the deformation of the metal plate 5 when the laminate 4 is press-molded. When the surface protective layer 84 contains a thermosetting resin, it is preferred that the surface protective layer 84 be incompletely cured by heat. The degree of curing can be, for example, B stage.

[0084] The surface protective layer 84 can be formed on the colored layer 83 by any method. For example, the surface protective layer 84 can be formed by coating, melt extrusion, lamination, or the like. Among these, coating is preferred because it allows the surface protective layer 84 to be easily formed. When forming a surface protective layer 84 having a two-layer structure, i.e., when coating the paint for forming the surface protective layer 84 twice, the drying conditions for the first and second coatings may be changed to adjust the degree of hardening of each layer.

[0085] 1.2.2. Protective Film The protective film 9 is provided on the surface protective layer 84 of the paint substitute film 8. The protective film 9 can prevent the paint substitute film 8 from being damaged and can also prevent the paint substitute film 8 from becoming soiled.

[0086] The thickness of the protective film 9 is preferably 10 μm or more, more preferably 25 μm or more, and even more preferably 38 μm or more. When the thickness is 10 μm or more, the rigidity is excellent. The thickness of the protective film 9 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. This is because the thinner the thickness of the protective film 9, the more economical it is. The protective film 9 may have a single-layer structure or a multi-layer structure.

[0087] The protective film 9 may contain a resin. Examples of resins include polyethylene resin, polyester resin, polypropylene resin, and polyvinyl chloride resin. Examples of polyester resins include homopolyester resin and copolymer polyester resin. One or more of these may be used. Among these, polyester resin is preferred because it has excellent heat resistance and can reduce uneven elongation of the paint substitute film 8. Polyethylene resin is also preferred.

[0088] Of both surfaces of the protective film 9, the surface roughness of at least the surface in contact with the hard coat layer is preferably 1 nm or more, more preferably 3 nm or more, and even more preferably 10 nm or more. When the surface roughness is 10 nm or more, the protective film 9 is easily transported and therefore easily handled. The surface roughness is preferably 1000 nm or less, more preferably 800 nm or less, and even more preferably 500 nm or less. The surface shape of the protective film 9 can be transferred to the surface protective layer 84, and a surface roughness of 1000 nm or less can prevent the appearance of the surface protective layer 84 from deteriorating.

[0089] Of both surfaces of the protective film 9, at least the surface that contacts the surface protective layer 84 is preferably subjected to a release treatment. For the release treatment, for example, a silicone-based release agent, a fluorine-based release agent, or a long-chain aliphatic release agent can be used. Among these, a silicone-based release agent is preferred because it is inexpensive.

[0090] The protective film 9 can be formed on the surface protective layer 84 of the paint substitute 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 substitute film 8, is preferred.

[0091] <1.3. Integrated Intensity Ratio> In the laminate 4, the integrated intensity ratio (i.e., the ratio of the first integrated intensity to the second integrated intensity) is 0.2 or more and 1.0 or less. The first integrated intensity is the integrated intensity of a diffraction peak representing a (1-10) plane derived from at least the alkylene terephthalate units of the first polyester and the alkylene terephthalate units of the second polyester. The second integrated intensity is the integrated intensity of a diffraction peak representing a (100) plane derived from at least the alkylene terephthalate units of the first polyester and the alkylene terephthalate units of the second polyester. Here, the (1-10) plane is preferably the (1-10) plane of the polyethylene terephthalate crystal. Therefore, the first integrated intensity is preferably the integrated intensity of a diffraction peak representing at least the (1-10) plane of the polyethylene terephthalate crystal. On the other hand, the (100) plane is preferably the (100) plane of the polyethylene terephthalate crystal. Therefore, the second integrated intensity is preferably the integrated intensity of at least the diffraction peak representing the (100) plane of polyethylene terephthalate. An example of the X-ray diffraction pattern of the laminate 4 is shown in FIG.

[0092] The integrated intensity ratio can be considered an index of crystallinity. This will be explained using the example of biaxially oriented polyethylene terephthalate (PET) film. In biaxially oriented PET film, the (100) plane of the PET crystal structure is a crystal plane containing a benzene ring. The (100) plane is approximately parallel to the plane of the biaxially oriented PET film (which can also be called the "main surface"). On the other hand, the (1-10) plane of the PET crystal structure is tilted relative to the (100) plane and therefore faces in a variety of directions compared to the (100) plane. Therefore, in the X-ray diffraction pattern of a biaxially oriented PET film, the integrated intensity of the diffraction peak representing the (1-10) plane is less affected by the crystallinity of PET than the integrated intensity of the diffraction peak representing the (100) plane (i.e., the crystallinity of PET). Therefore, the smaller the ratio of the integrated intensity of the diffraction peak representing the (1-10) plane to the integrated intensity of the diffraction peak representing the (100) plane, the higher the crystallinity of the PET. Therefore, this ratio can be regarded as an index of the crystallinity. This principle also applies to the biaxially oriented polyester film 81 of the laminate 4. Therefore, the integrated intensity ratio (i.e., the ratio of the first integrated intensity to the second integrated intensity) can be regarded as an index of the crystallinity.

[0093] Because the integrated intensity ratio is 1.0 or less, the crystallinity is not excessively low, and therefore the heat resistance of the biaxially oriented polyester film 81 can be improved. This makes it possible to reduce or prevent the occurrence of irregularities on the surface of the biaxially oriented polyester film 81 that may be caused by the heat received by the paint substitute film 8 when the laminate 4 is press-molded. As a result, it is possible to reduce or prevent deterioration of the surface shape of the paint substitute film 8 that may be caused by the heat. Therefore, it is possible to reduce or prevent deterioration of the appearance (i.e., appearance) of the paint substitute film 8 that may be caused by the heat.

[0094] The integrated intensity ratio is preferably 0.9 or less, but may also be 0.8 or less, 0.7 or less, 0.6 or less, or 0.5 or less.

[0095] On the other hand, because the integrated intensity ratio is 0.2 or more, the degree of crystallinity is not excessively high, and therefore it is possible to avoid an excessive decrease in adhesive strength with the metal plate 5. This makes it possible to reduce or prevent peeling of the paint substitute film 8 from the metal plate 5, particularly peeling of the paint substitute film 8 from the metal plate 5 after the laminate 4 has been press-molded.

[0096] The integrated intensity ratio is preferably 0.3 or more, but may also be 0.4 or more, 0.5 or more, 0.6 or more, or 0.7 or more.

[0097] The integrated intensity ratio can be controlled, for example, by the heat setting temperature or lamination temperature (specifically, the thermocompression bonding temperature). The higher the heat setting temperature, the higher the crystallinity of the biaxially oriented polyester film 81 before lamination, resulting in a lower integrated intensity ratio. The higher the lamination temperature (specifically, the thermocompression bonding temperature), the more the crystals melt, resulting in a higher integrated intensity ratio. The integrated intensity ratio is also affected by the type of first polyester, the type of second polyester, the stretching temperature, the stretching ratio, and the like. When the laminate 4 includes a protective film 9, the protective film 9 is removed before X-ray diffraction (i.e., measurement of X-ray diffraction intensity).

[0098] 1.4. Manufacturing Method of Laminate The manufacturing method of the laminate 4 includes a step of pressure-bonding a heated metal plate 5 and a paint substitute film 8 or composite film 7 (hereinafter, sometimes referred to as a "pressure-bonding step"). The manufacturing method of the laminate 4 preferably further includes a step of heating the metal plate 5 (hereinafter, sometimes referred to as a "heating step") and a step of cooling the metal plate 5 to which the paint substitute film 8 or composite film 7 has been pressure-bonded (hereinafter, sometimes referred to as a "cooling step"). Note that when the metal plate 5 is in a roll shape and the paint substitute film 8 or composite film 7 is also in a roll shape, the laminate 4 can be manufactured by a roll-to-roll method.

[0099] 1.4.1. Step of Heating Metal Plate In this step, the metal plate 5 is heated. By heating the metal plate 5, it becomes possible to thermocompression bond the metal plate 5 and the paint substitute film 8 or the composite film 7.

[0100] <1.4.2. Pressure-bonding step> In this step, the heated metal plate 5 and the paint substitute film 8 or the composite film 7 are pressure-bonded together. Specifically, the two are pressure-bonded together with the layer A 812 of the paint substitute film 8 or the layer A 812 of the composite film 7 facing the heated metal plate 5.

[0101] In this step, the temperature of the heated metal plate 5 is preferably equal to or higher than the melting point of the A layer 812. At a temperature equal to or higher than the melting point of the A layer 812, the A layer 812 can be melted, thereby enabling the metal plate 5 and the paint substitute film 8 or the composite film 7 to be thermocompression bonded to each other. The temperature of the heated metal plate 5 is more preferably equal to or higher than the sum of the melting point of the A layer 812 and 20°C, even more preferably equal to or higher than the sum of the melting point of the A layer 812 and 30°C, even more preferably equal to or higher than the sum of the melting point of the A layer 812 and 35°C, and even more preferably equal to or higher than the sum of the melting point of the A layer 812 and 40°C. Thus, when the melting point of the A layer 812 is 217°C, the temperature of the heated metal plate 5 is more preferably equal to or higher than 237°C, even more preferably equal to or higher than 247°C, even more preferably equal to or higher than 252°C, and even more preferably equal to or higher than 257°C. When the temperature of the heated metal plate 5 is equal to or higher than the sum of the melting point of layer A 812 and 20°C, the viscosity of layer A 812 can be effectively reduced, thereby improving the adhesive strength with the metal plate 5.

[0102] The temperature of the heated metal plate 5 is preferably equal to or lower than the sum of the melting point of the B layer 811 and 10°C, more preferably equal to or lower than the sum of the melting point of the B layer 811 and 8°C, and even more preferably equal to or lower than the sum of the melting point of the B layer 811 and 7°C. Therefore, when the melting point of the B layer 811 is 255°C, the temperature of the heated metal plate 5 is more preferably equal to or lower than 265°C, even more preferably equal to or lower than 263°C, and even more preferably equal to or lower than 262°C. When the temperature of the heated metal plate 5 is equal to or lower than the sum of the melting point of the B layer 811 and 10°C, excessive melting of the crystals of the B layer 811 can be avoided, and therefore, excessive deterioration of the heat resistance of the biaxially oriented polyester film 81 can be avoided. The temperature of the heated metal plate 5 may also be equal to or lower than the melting point of the B layer 811.

[0103] 1.4.3. Cooling Step The method for producing the laminate 4 preferably includes a step of cooling the metal plate 5 to which the paint substitute film 8 or composite film 7 is bonded. Because cooling can suppress recrystallization, an excessively high crystallinity of at least the A layer 812 after lamination can be avoided. Therefore, an excessively low adhesive strength with the metal plate 5 can be avoided. This further reduces or prevents peeling of the paint substitute film 8 from the metal plate 5, particularly peeling of the paint substitute film 8 from the metal plate 5 after press-forming the laminate 4. An example of a cooling method is water-cooling the metal plate 5 to which the paint substitute film 8 or composite film 7 is bonded. Examples of water-cooling methods include immersing the metal plate 5 to which the paint substitute film 8 or composite film 7 is bonded in a water tank, and spraying water onto the metal plate 5 to which the paint substitute film 8 or composite film 7 is bonded. Examples of the water used in the water tank or sprayed include tap water, well water, rainwater, and pure water. Chemicals may be added to the water. The water in the tank or the water to be sprayed is preferably cold water. The temperature of the water may be, for example, 5°C or higher, or 15°C or higher. The temperature of the water is preferably 60°C or lower, more preferably 45°C or lower, even more preferably 35°C or lower, and even more preferably 30°C or lower.

[0104] In order to effectively suppress recrystallization, it is preferable to start cooling within 5 seconds after the heated metal plate 5 and the paint substitute film 8 or composite film 7 are pressed together (for example, the metal plate 5 to which the paint substitute film 8 or composite film 7 is pressed is immersed in a water tank within 5 seconds after the pressing), more preferably within 3 seconds, and even more preferably within 2 seconds.

[0105] <2. Molded Product> The molded product of this embodiment can be obtained by press-molding the laminate 4. Cold press-molding is preferred as the press-molding method. The cold press-molding may be, for example, drawing, i.e., drawing processing, or stretch-molding, i.e., stretch-processing. Note that if the surface protection layer 84 of the laminate 4 has not yet hardened, the surface protection layer 84 may be applied as needed after press-molding.

[0106] The molded article can be used, for example, in vehicles, ships (e.g., motorboats), home appliances, and audio products. Of these, vehicles are preferred. Examples of vehicles include automobiles, motorcycles, railroad cars, and airplanes. Of these, automobiles and motorcycles are preferred. When the molded article is used in a vehicle, it is preferably used as a vehicle exterior part. As a vehicle exterior part, an outer panel is preferred, and an automobile outer panel is more preferred. The molded article may also be used as a construction member or a steel plate product.

[0107] 3. Various modifications can be made to the above-described embodiment. Various modifications can be made to the above-described embodiment. For example, one or more of the following modifications can be selected and made to the above-described embodiment.

[0108] In the above embodiment, the laminate 4 includes the protective film 9. However, the present embodiment is not limited to this configuration. That is, the laminate 4 does not have to include the protective film 9.

[0109] In the above embodiment, the paint substitute film 8 includes the adhesive layer 82. However, the present embodiment is not limited to this configuration. That is, the laminate 4 does not need to include the adhesive layer 82.

[0110] In the above embodiment, the colored layer 83 is provided on the adhesive layer 82. However, the present embodiment is not limited to this configuration. Another layer may be present between the adhesive layer 82 and the colored layer 83.

[0111] In the above embodiment, the configuration in which the surface protective layer 84 is provided on the colored layer 83 has been described. However, the present embodiment is not limited to this configuration. Another layer may be present between the colored layer 83 and the surface protective layer 84.

[0112] In the above embodiment, the configuration in which the protective film 9 is provided on the surface protective layer 84 has been described. However, the present embodiment is not limited to this configuration. Another layer may be present between the surface protective layer 84 and the protective film 9.

[0113] In the above embodiment, the biaxially oriented polyester film 81 has been described as having a two-layer structure. However, this embodiment is not limited to this structure. For example, the biaxially oriented polyester film 81 may include another layer between the B layer 811 and the A layer 812. The biaxially oriented polyester film 81 may also include another layer between the B layer 811 and the colored layer 83.

[0114] The present invention will be described in more detail below with reference to examples and comparative examples. Unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass".

[0115] <Measurement or Evaluation Method> (A) Intrinsic Viscosity 0.2 g of polyester was dissolved in 50 ml of a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (60 / 40 (mass ratio)), and the intrinsic viscosity was measured using an Ostwald viscometer at 30° C. The unit is dL / g.

[0116] (B) Melting Point (Tm) In differential scanning calorimetry of the polyester, the polyester was heated and melted at 300°C for 5 minutes, and then quenched with liquid nitrogen. Using a DSC-60 differential scanning calorimeter (Shimadzu Corporation), 10 mg of the quenched polyester was heated at 20°C / min. In the DSC curve obtained, the endothermic peak temperature due to crystalline melting was determined as the melting point. Here, the endothermic peak is an endothermic peak of 0.05 J / g or more associated with crystalline melting that appears at a temperature higher than the temperature at which a baseline shift corresponding to the glass transition point occurs. Meanwhile, the melting point of Layer A was determined in the same manner, except that a sample was scraped from Layer A. Specifically, a sample scraped from Layer A was heated and melted at 300°C for 5 minutes, and then quenched with liquid nitrogen. Using a DSC-60 differential scanning calorimeter (Shimadzu Corporation), 10 mg of the quenched sample was heated at 20°C / min. In the DSC curve thus obtained, the endothermic peak temperature due to crystalline melting was determined as the melting point. The melting point of layer B was determined in the same manner as the melting point of layer A, except that a sample was scraped off from layer B.

[0117] (C) Thickness of each layer of the paint substitute film A sample measuring 2 mm in the machine direction and 2 cm in the width direction was cut from the paint substitute film, fixed in an embedding capsule, and embedded in epoxy resin. The embedded sample was cut perpendicular to the width direction using a microtome (Supercut, manufactured by Reichert-Jung) to obtain thin film slices 50 μm thick. Observations and photographs were taken using a scanning electron microscope (Hitachi 4300SE / N) at an accelerating voltage of 20 kV, and the thickness of each layer was measured from the photographs, and the average thickness of five points on each layer was calculated.

[0118] (D) Plane Orientation Coefficient According to JIS K 7142-1996 Method A, the refractive index in the machine direction (Nx), the refractive index in the width direction (Ny), and the refractive index in the thickness direction (Nz) of each of the A layer and the B layer of a biaxially oriented polyester film without easy-adhesion treatment were measured using an Abbe refractometer with sodium D line as a light source. Then, the plane orientation coefficient ΔP of each layer was calculated using the following formula. Plane orientation coefficient ΔP = (Nx + Ny) / 2 - Nz

[0119] (E) Heat Shrinkage Ratio To determine the heat shrinkage ratio in the MD direction, five test pieces measuring 10 mm wide x 150 mm long were cut out from a biaxially oriented polyester film without an easy-adhesion treatment. The length direction of these test pieces coincided with the machine direction of the biaxially oriented polyester film, i.e., the MD direction. A pair of marks spaced 100 mm ± 2 mm apart was marked in the center of the test piece. The distance between the marks (i.e., the distance between the pair of marks) of the test piece before heating was measured with an accuracy of 0.1 mm. The test piece was hung in a hot air dryer (PHH-202, manufactured by Espec Corporation) in an unloaded state and heated at 150°C for 15 minutes. The test piece was removed from the thermostatic chamber and cooled to room temperature, after which the distance between the marks was measured with an accuracy of 0.1 mm. The heat shrinkage ratio in the MD direction was then calculated using the following formula: Heat shrinkage ratio (%) = {(L ０ -L) / L ０}×100 where L is the gauge length after heat treatment, L ０ is the gauge length before heat treatment. ０ As described above, the average value of five test specimens was substituted for . The thermal shrinkage in the TD direction was determined in the same manner as the thermal shrinkage in the MD direction. Specifically, five test specimens measuring 10 mm wide x 150 mm long were cut out from a biaxially oriented polyester film without an easy-adhesion treatment. The length direction of these test specimens coincided with the width direction of the biaxially oriented polyester film, i.e., the TD direction. A pair of marks spaced 100 mm ± 2 mm apart was marked in the center of the test specimen. The distance between the marks (i.e., the distance between the pair of marks) of the test specimen before heating was measured with an accuracy of 0.1 mm. The test specimen was hung in a hot air dryer (PHH-202, manufactured by Espec Corporation) in an unloaded state and heated at 150 °C for 15 minutes. After removing the test specimen from the thermostatic chamber and cooling to room temperature, the distance between the marks was measured with an accuracy of 0.1 mm. The thermal shrinkage in the TD direction was then determined using the above formula.

[0120] (F) X-ray Diffraction Using CuKα radiation as the X-ray source, X-ray diffraction intensity was measured by the multiple peak separation method under the following conditions: divergence slit 1 / 2°, scattering slit 1 / 2°, receiving slit 0.15 mm, scan speed 5° / min, and incident angle 0.1°. The sample used was a metal plate (specifically, a galvanized steel plate, as described below) to which a biaxially oriented polyester film that had been treated for easy adhesion was bonded. X-rays were irradiated along the flow direction of the biaxially oriented polyester film (i.e., the metal plate to which a biaxially oriented polyester film that had been treated for easy adhesion was bonded). The ratio of the integrated intensity of the diffraction peak representing the (1-10) plane of polyethylene terephthalate to the integrated intensity of the diffraction peak representing the (100) plane of polyethylene terephthalate (hereinafter, this ratio may be referred to as the "(1-10) plane / (100) plane") was determined. In the biaxially oriented polyester film, the (100) plane is a crystal plane containing a benzene ring. This (100) plane is approximately parallel to the plane of the biaxially oriented polyester film (which may also be called the "principal surface").

[0121] (G) Image Distortion: A 0.6 mm thick zinc alloy-plated steel sheet (hereinafter sometimes referred to as "galvanized steel sheet") heated to the temperature shown in Table 1 or Table 2 was crimped onto a paint substitute film. The galvanized steel sheet with the paint substitute film crimped onto it was immersed in a water tank 2 seconds after crimping, allowing it to cool to room temperature. A test plate measuring 180 mm wide and 180 mm long was cut from the galvanized steel sheet with the paint substitute film crimped onto it. To draw the test plate, a die with a drawing ratio of 1.3 was used to hold the periphery of the test plate with a load of 15 t, and then the center of the test plate was pressed at room temperature with a load of 100 t. The drawn test plate, i.e., the molded product, was placed on the floor, horizontally offset 50 cm from directly below a fluorescent lamp located 2.5 m above the floor. The molded product was placed on the floor with the inner bottom surface of the molded product facing upwards, specifically with the hard coat layer of the paint substitute film on the inner bottom surface of the molded product facing the fluorescent light. The image of the fluorescent light reflected on the molded product was visually observed and the degree of distortion of the image was judged according to the following criteria. Judgment A: Almost no distortion in the image of the fluorescent light Judgment B: Part of the image of the fluorescent light is distorted Judgment C: The image of the fluorescent light is distorted overall

[0122] (H) Evaluation of Adhesion After Cold Press Molding A cross (X) mark was cut into the center of the molded product (i.e., the drawn test plate) produced by "image distortion," specifically on the inner bottom surface of the molded product. Specifically, an X-shaped cut was made on the inner bottom surface of the molded product using a utility knife, reaching not only the paint substitute film but also the galvanized steel sheet. The molded product was placed in a retort processor and treated at 120°C, 0.2 MPa, and for 2 hours. After treatment, the molded product was judged for the adhesion state of the paint substitute film (specifically, the adhesion state between the paint substitute film and the galvanized steel sheet) according to the following criteria: Judgment A: No peeling Judgment B: Partial peeling (partial whitening observed) Judgment C: Peeling (whitening observed throughout)

[0123] <Raw Materials for Biaxially Oriented Polyester Film> The following resin composition was used to form Layer B. Resin Composition A A mixture of Resin B and Resin C was used as Resin Composition A. Resin B: PET resin, IV = 0.75 dL / g, melting point 255°C, 97.0 parts by mass. Resin C: PET resin containing 0.036% by mass of silica particles (average particle size 1.7 μm), IV = 0.75 dL / g, melting point 255°C, 3.0 parts by mass.

[0124] Resin Composition D A mixture of the following resins E and F was used as resin composition D. Resin E: PET resin, IV = 0.62 dL / g, melting point 255°C, 90.0 parts by mass Resin F: PET resin containing 0.72% by mass of silica particles (average particle size 2.7 μm), IV = 0.62 dL / g, melting point 255°C, 10.0 parts by mass

[0125] Resin Composition G A mixture of the following resins F and H was used as resin composition G. Resin F: PET resin containing 0.72% by mass of silica particles (average particle size 2.7 μm), IV = 0.62 dL / g, melting point 255°C, 10 parts by mass Resin H: copolymer polyester resin containing 92.1 mol% of ethylene terephthalate units and 7.9 mol% of ethylene isophthalate units, IV = 0.62 dL / g, melting point 233°C, 90 parts by mass

[0126] The following resins were used to form layer A: Resin I: a copolymer polyester resin containing 86.0 mol % of ethylene terephthalate units and 14.0 mol % of ethylene isophthalate units, with an IV of 0.70 dL / g and a melting point of 217°C.

[0127] Resin J: Copolymer polyester resin containing 89.0 mol% ethylene terephthalate units and 11.0 mol% ethylene isophthalate units, IV = 0.63 dL / g, melting point 225°C

[0128] Resin K: Copolymer polyester resin containing 80.0 mol% ethylene terephthalate units and 20.0 mol% ethylene isophthalate units, IV = 0.63 dL / g, melting point 198°C

[0129] Example 1: Preparation of an adhesion-enhanced biaxially oriented polyester film. The molding material for Layer B (specifically, Resin Composition A) was melted at 280°C in a first extruder, and the molding material for Layer A (specifically, Resin I) was melted at 280°C in a second extruder. These were then laminated using a die and extruded onto a cooling drum. The unstretched sheet solidified on the cooling drum was stretched 3.0 times in the machine direction at 80°C. The surface of Layer B was coated with an epoxy adhesive (i.e., an adhesive containing an epoxy resin), and then stretched 3.5 times in the width direction at 130°C. The width-stretched sheet was heat-set at 215°C and then subjected to a 5% relaxation process in the width direction. This resulted in an adhesion-enhanced biaxially oriented polyester film with a Layer A thickness of 15 μm and a Layer B thickness of 35 μm. The adhesion-enhanced biaxially oriented polyester film had an adhesion-enhanced layer thickness of 30 nm. The adhesion-enhanced biaxially oriented polyester film was wound into a roll.

[0130] Preparation of Paint Substitute Film: While unwinding the adhesion-treated biaxially oriented polyester film, a coating solution was applied to the adhesion layer of the biaxially oriented polyester film using a comma coater, followed by drying in a drying oven at 90°C. The coating solution used was a solvent-based paint containing an acrylic urethane resin and 10% by weight of aluminum pigment, with a non-volatile content of 35% by weight. This resulted in a raw roll, i.e., a raw roll comprising the adhesion-treated biaxially oriented polyester film and a 20 μm-thick colored layer formed on the adhesion layer. That is, a raw roll comprising the biaxially oriented polyester film, the adhesion layer, and the 20 μm-thick colored layer was obtained. The raw roll was then wound into a roll. While unwinding the raw roll, the hard coat paint described below was applied to the colored layer using a comma coater to a thickness of 30 μm, and the hard coat layer was thoroughly dried in a drying oven at 90°C. This procedure resulted in a paint substitute film. The hard coat layer constituting the paint substitute film was in a semi-cured state, i.e., incompletely cured.

[0131] Hard coat paint A four-necked flask equipped with a condenser, stirrer, thermometer, and nitrogen inlet tube was charged with 150 parts by mass of methyl isobutyl ketone, and the temperature was raised 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 containing 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 Fancryl 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 one hour after the completion of the monomer addition, 0.02 parts by mass of azobisisobutyronitrile was added every hour to continue the reaction, and the reaction was continued until the unreacted monomer in the monomer solution was 1% or less. When the unreacted monomer content was 1% or less, the reaction was terminated by cooling, yielding an acrylic copolymer solution with a solids 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 Corporation, a polyisocyanate derivative of hexamethylene diisocyanate) was added as a polyisocyanate compound, and methyl isobutyl ketone was added so that the solids content was 30% by mass, followed by stirring, yielding a hard coat coating material.

[0132] Preparation of galvanized steel sheet with pressure-bonded paint substitute film A paint substitute film was pressure-bonded to a galvanized steel sheet (specifically, a steel sheet with a thickness of 0.6 mm and plated with a zinc alloy) heated to the temperature shown in Table 1. The galvanized steel sheet with the pressure-bonded paint substitute film was immersed in a water tank (specifically, a water tank filled with water at 23°C) within 2 seconds of bonding, and cooled to room temperature. This yielded a galvanized steel sheet with a pressure-bonded paint substitute film.

[0133] Preparation of biaxially oriented polyester film without easy-adhesion treatment A biaxially oriented polyester film without easy-adhesion treatment was prepared in the same manner as the easy-adhesion treated biaxially oriented polyester film, except that the easy-adhesion treatment was not carried out.

[0134] Examples 2 to 4 and Comparative Examples 1 to 6 (Strictly speaking, Comparative Examples 1 to 2 and 4 to 6) Biaxially oriented polyester films with easy-adhesion treatment, paint substitute films, and biaxially oriented polyester films without easy-adhesion treatment were produced in the same manner as in Example 1, except that a resin shown in Table 1 or Table 2 was used as the resin for forming Layer A, that the film-forming conditions (stretching ratio, stretching temperature, heat setting temperature) shown in Table 1 or Table 2 were adopted, and that the thicknesses of Layer A and Layer B were as shown in Table 1 or Table 2. Galvanized steel sheets with paint substitute films pressure-bonded thereto were produced in the same manner as in Example 1, except that the temperature to which the zinc-plated steel sheets were heated was the temperature shown in Table 1 or Table 2.

[0135] Results: A table containing the results is shown below.

[0136] The (1-10) plane / (100) plane in these tables is a value obtained by measuring the X-ray diffraction intensity using a galvanized steel sheet to which a biaxially oriented polyester film that had been subjected to an easy-adhesion treatment was pressure-bonded as a sample. When the X-ray diffraction intensity was measured by the above-mentioned method using a galvanized steel sheet to which a paint substitute film had been pressure-bonded as a sample, the (1-10) plane / (100) plane obtained was the same as the (1-10) plane / (100) plane obtained when a galvanized steel sheet to which a biaxially oriented polyester film that had been subjected to an easy-adhesion treatment was pressure-bonded as a sample.

[0137] In Comparative Example 1, in which the (1-10) plane / (100) plane ratio was 0.12, the adhesiveness was rated C. This is thought to be because the crystallinity was excessively high and, therefore, the adhesive strength with the metal plate was excessively low.

[0138] In Comparative Example 4, in which the (1-10) plane / (100) plane ratio was 0.07, the adhesiveness was rated B. This is thought to be because the crystallinity was excessively high, and therefore the adhesive strength with the metal sheet was excessively low. Thus, the adhesiveness of Comparative Example 4 was superior to that of Comparative Example 1. In relation to this, since the thermal shrinkage rate of Comparative Example 4 was smaller than that of Comparative Example 1, it is thought that in Comparative Example 4, the thermal shrinkage when the galvanized steel sheet and the paint substitute film were pressure-bonded was small, and therefore the decrease in adhesive strength with the galvanized steel sheet that could be caused by thermal shrinkage was small. In addition, since the plane orientation coefficient of Layer A in Comparative Example 4 was smaller than that of Layer A in Comparative Example 1, it is thought that in Comparative Example 4, Layer A was more likely to flow when the galvanized steel sheet and the paint substitute film were pressure-bonded.

[0139] In Comparative Example 5, in which the (1-10) plane / (100) plane ratio was 0.11, the adhesiveness was rated C. As can be seen, the adhesiveness of Comparative Example 5 was inferior to that of Comparative Example 4. Since the thermal shrinkage rate of Comparative Example 5 was greater than that of Comparative Example 4, it is considered that in Comparative Example 5, the thermal shrinkage when the galvanized steel sheet and the paint substitute film were pressure-bonded together was large, and therefore the decrease in adhesive strength with the galvanized steel sheet, which can be attributed to the thermal shrinkage, was large.

[0140] In Comparative Example 6, the (1-10) plane / (100) plane ratio was 1.48, but the adhesion was rated B. This is thought to be because the thermal shrinkage rate was extremely large, which resulted in extremely large thermal shrinkage when the galvanized steel sheet and the paint substitute film were pressure-bonded together, and therefore the decrease in adhesive strength with the galvanized steel sheet that could be caused by thermal shrinkage was also extremely large.

[0141] In Comparative Example 2, where the (1-10) plane / (100) plane ratio was 1.21, the image distortion was rated C. This is thought to be because the crystallinity was excessively low, and therefore the heat resistance of the biaxially oriented polyester film was poor. In Comparative Example 6, where the (1-10) plane / (100) plane ratio was 1.48, the image distortion was also rated C.

[0142] In Example 4, the (1-10) plane / (100) plane ratio was 0.32, but the image distortion was B. This is thought to be because the plane orientation coefficient of layer B in Example 4 was small, and therefore wrinkles or bubbles were generated in the paint substitute film due to the heat received by the paint substitute film when the galvanized steel sheet and the paint substitute film were pressure-bonded together (i.e., the heat during lamination).

[0143] In Comparative Example 4, the (1-10) plane / (100) plane ratio was 0.07, but the image distortion was B. This is thought to be because the plane orientation coefficient of the B layer was small, causing wrinkles or bubbles to form in the paint substitute film due to the heat generated during lamination.

[0144] Although the image distortion in both Example 4 and Comparative Example 4 was B, the degree of distortion in Example 4 was smaller than the degree of distortion in Comparative Example 4.

[0145] In Comparative Example 5, the (1-10) plane / (100) plane ratio was 0.11, but the image distortion was B. This is thought to be because the plane orientation coefficient of the B layer was small, causing wrinkles or bubbles to form in the paint substitute film due to the heat generated during lamination.

[0146] The present invention can provide laminates, molded articles, vehicle exterior parts, and the like, and is therefore industrially applicable.

[0147] 4...Laminate, 5...Metal plate, 7...Composite film, 8...Paint substitute film, 9...Protective film, 81...Biaxially oriented polyester film, 82...Adhesive layer, 83...Colored layer, 84...Surface protective layer, 811...Layer B, 812...Layer A

Claims

1. A laminate comprising a metal plate and a paint substitute film laminated to the metal plate, wherein the paint substitute film comprises a biaxially oriented polyester film, a colored layer, and a surface protective layer, the biaxially oriented polyester film comprises a first layer and a second layer, the first layer is located between the second layer and the colored layer, the first layer contains a first polyester containing alkylene terephthalate units, the second layer contains a second polyester containing alkylene terephthalate units, the melting point of the first layer is higher than the melting point of the second layer, In an X-ray diffraction pattern of the laminate, the ratio of the integrated intensity of a diffraction peak representing a (1-10) plane derived from at least the alkylene terephthalate units of the first polyester and the alkylene terephthalate units of the second polyester to the integrated intensity of a diffraction peak representing a (100) plane derived from at least the alkylene terephthalate units of the first polyester and the alkylene terephthalate units of the second polyester is 0.2 or more and 1.0 or less, and the (1-10) plane is the following crystal plane: Laminate.

2. The laminate according to claim 1, wherein the paint replacement film further comprises an adhesive layer, the adhesive layer being located between the biaxially oriented polyester film and the color layer.

3. The laminate according to claim 2, wherein the thickness of the adhesive layer is 10 nm or more and 200 nm or less.

4. The laminate according to claim 1, wherein the colored layer contains a resin and a colorant.

5. The laminate according to claim 1, wherein the alkylene terephthalate units of the first polyester comprise ethylene terephthalate units, the alkylene terephthalate units of the second polyester comprise ethylene terephthalate units, the (1-10) plane is a (1-10) plane derived from at least the ethylene terephthalate units of the first polyester and the ethylene terephthalate units of the second polyester, and the (100) plane is a (100) plane derived from at least the ethylene terephthalate units of the first polyester and the ethylene terephthalate units of the second polyester.

6. The laminate according to claim 5, wherein the ethylene terephthalate units account for 85 mol % or more of the repeating units of the first polyester, and the ethylene terephthalate units account for 60 mol % or more of the repeating units of the second polyester, when the repeating units of the second polyester are taken as 100 mol %.

7. The laminate according to claim 1, further comprising a protective film, wherein the metal plate, the paint substitute film, and the protective film are stacked in this order.

8. The laminate of claim 1 used to manufacture exterior vehicle parts.

9. A molded product obtained by pressing the laminate according to any one of claims 1 to 8.

10. A vehicle exterior part obtained by pressing the laminate according to any one of claims 1 to 8.

11. A method for manufacturing a laminate according to any one of claims 1 to 8, comprising the steps of: heating the metal plate; and pressing the heated metal plate and the paint substitute film or composite film together, wherein the composite film comprises the paint substitute film and a protective film provided on the surface protective layer of the paint substitute film.

12. The method for producing a laminate according to claim 11, further comprising the step of initiating cooling within 5 seconds after the metal plate and the paint substitute film or the composite film are pressed together.

13. A method for producing a laminate according to claim 11, wherein the first layer of the paint substitute film or composite film to be pressed onto the metal plate has a plane orientation coefficient of 0.165 or more and 0.180 or less, and the second layer of the paint substitute film or composite film to be pressed onto the metal plate has a plane orientation coefficient of 0.100 or more and 0.135 or less.

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