Film laminate

Abstract

To provide a film laminate which has high versatility, uses a polyester resin (X) having low dielectric characteristics and transparency as a constituent member, and has ultraviolet absorption performance.SOLUTION: A film laminate has a polyester layer (X) and a resin layer (Y), and has light transmittance at a wavelength of 380 nm of 20% or less, wherein the polyester layer (X) has a laminated structure having two or more layers, and has a layer A containing polycyclohexylenedimethylene terephthalate having a terephthalic acid unit as a dicarboxylic acid component (a-1), and a 1,4-cyclohexanedimethanol unit as a diol component (a-2), in at least one surface layer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a film laminate. [Background technology]

[0002] In recent years, the increasing performance and functionality of electrical and electronic devices has created a need for high-speed information communication. For example, with the launch of 5G (fifth generation mobile communication system) high-speed communication services for smartphones, high-speed communication services are becoming widespread not only in the consumer sector but also in the industrial sector (factories, automobiles, and other vehicles). 5G's high-speed, large-capacity data communications use radio waves in the "millimeter wave" band (wavelength 1-10 mm, frequency 30-300 GHz). Advantages of millimeter waves include the large amount of data that can be transmitted at one time and the high-resolution images that can be obtained.

[0003] On the other hand, when a high-frequency digital signal such as the millimeter wave is transmitted through a circuit board, a dielectric loss occurs in which part of the transmitted digital signal is consumed as heat on the wiring of the circuit board, and the attenuated digital signal arrives at the receiving side, resulting in so-called "transmission loss." Therefore, measures to reduce transmission loss are also required for the materials used. The transmission loss is the sum of dielectric loss and conductor loss, and the dielectric loss α d is calculated from the following formula (1).

[0004]

number

[0005] where f is frequency, c is the speed of light, and ε r is the relative permittivity, and tan δ is the dielectric loss tangent.

[0006] For example, in FPC (Flexible Printed Circuits), which is a flexible circuit board made of resin film and copper foil, the resin film has a dielectric loss α d More specifically, a reduction in εr Attempts have been made to reduce the tan δ, especially to reduce the tan δ. Specifically, examples of fluororesins include liquid crystal polymer (LCP), which has a dielectric loss of about 1 / 10 of polyimide (PI), which is used as a material for FPCs; cycloolefin polymer (COP), which has a dielectric loss of about 1 / 50; and polytetrafluoroethylene (PTFE), which has a dielectric loss of about 1 / 100 (Non-Patent Document 1).

[0007] However, LCP and COP have the problem of low heat resistance, and fluororesin has low adhesion strength to other materials such as copper foil and is difficult to drill holes with a UV laser due to its UV absorption. Furthermore, fluororesin is expensive. Therefore, there is a demand for a resin film that has low dielectric loss and is versatile.

[0008] Polyester films are a versatile resin film that has excellent heat resistance, weather resistance, mechanical strength, transparency, and other properties, and is readily available at a reasonable price. As a result, polyester films are used in a variety of applications, including packaging materials and optical applications, but their low dielectric properties have not been extensively studied.

[0009] For example, Patent Document 1 discloses a laminated biaxially oriented polyester film containing 5 to 45% by volume of voids inside as a polyester film with excellent low dielectric properties. The inclusion of voids allows voids (air) to be dispersed, thereby achieving a low dielectric constant and a low dielectric loss tangent.

[0010] Recently, a "transparent antenna film" has been studied, in which an invisible ultrafine metal mesh wiring is formed on a transparent film. There is a demand for reducing the dielectric loss of the film, more specifically, for reducing the dielectric constant and dielectric loss tangent of the film. Millimeter waves are more susceptible to interference from nearby products than conventional microwaves, which means there is less freedom in where antennas can be installed. In addition, because radio waves tend to travel in a direction that is stronger than conventional waves, it is necessary to install more antennas to ensure a better communication environment than before. The transparent antenna film being considered to address these issues does not impair the design, and can be attached not only to mobile devices but also to buildings such as window glass and car glass to receive 5G signals. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-352470 [Non-patent literature]

[0012] [Non-Patent Document 1] "Development Trends of High-Frequency Compatible Materials and Their Applications to 5G and Millimeter-Wave Radar," Technical Information Association, Chapter 3, Section 2, pp. 77-84 "Development Trends of High-Speed, High-Frequency Compatible FPCs and Low Transmission Loss" Summary of the Invention [Problem to be solved by the invention]

[0013] The void-containing laminated biaxially stretched polyester film described in Patent Document 1 is formed by mixing different materials to form the voids. In such cases, it is difficult to control the size of the voids or the dispersion state of the different materials. For example, if the dispersion state of the different materials is insufficient, the desired low dielectric properties may not be obtained. Furthermore, depending on the different materials used, the inherent transparency of polyester film may not be achieved, and in addition, light may be refracted at the cavity interface, reducing transparency.

[0014] The problem to be solved by the present invention is to solve the above problems and to provide a film laminate that has excellent low dielectric properties and transparency and can be used outdoors. [Means for solving the problem]

[0015] The present inventors have conducted extensive research to achieve the above object, and as a result have completed the present invention. In one aspect, the present invention is summarized as follows [1] to

[23] . [1] A film laminate comprising a polyester layer (X) and a resin layer (Y), the film having a light transmittance of 20% or less at a wavelength of 380 nm, the polyester layer (X) having a laminate structure of two or more layers, and at least one surface layer having a layer A containing polycyclohexylene dimethylene terephthalate having terephthalic acid units as the dicarboxylic acid component (a-1) and 1,4-cyclohexanedimethanol units as the diol component (a-2). [2] The film laminate according to the above [1], which has an adhesive layer between the polyester layer (X) and the resin layer (Y). [3] The film laminate according to [2] above, wherein the adhesive layer has a relative dielectric constant of 3.9 or less. [4] The film laminate according to the above [2] or [3], wherein the thickness of the adhesive layer is 1 to 200 μm. [5] The film laminate according to any one of the above [1] to [4], which has a cured resin layer (CFB) on at least one side of the polyester layer (X). [6] The film laminate according to [5] above, which comprises a metal layer on the cured resin layer (CFB). [7] The film laminate according to [6] above, wherein the metal layer is patterned. [8] The film laminate according to [6] or [7] above, wherein the metal layer is made of copper or silver. [9] The film laminate according to any one of the above [5] to [8], which has a cured resin layer (CFA) on the side of the polyester layer (X) opposite to the side on which the cured resin layer (CFB) is laminated.

[10] The film laminate according to any one of the above [5] to [9], wherein at least one of the cured resin layer (CFA) and the cured resin layer (CFB) is formed from a resin composition containing a crosslinking agent in an amount of 70 mass% or more relative to the non-volatile components.

[11] The film laminate according to any one of the above [1] to

[10] , wherein the polycyclohexylene dimethylene terephthalate further has an isophthalic acid unit as the dicarboxylic acid component (a-1).

[12] The film laminate according to any one of the above [1] to

[11] , wherein a layer other than the layer A in the polyester layer (X) contains polyethylene terephthalate.

[13] The film laminate according to any one of the above [1] to

[12] , wherein the relative dielectric constant of the layer A at 28 GHz is 3.0 or less.

[14] The film laminate according to any one of the above [1] to

[13] , wherein the dielectric loss tangent of the layer A at 28 GHz is 0.0060 or less.

[15] The film laminate according to any one of the above [1] to

[14] , wherein the resin layer (Y) is a polyester film.

[16] The film laminate according to any one of the above [1] to

[15] , wherein the resin layer (Y) contains an ultraviolet absorber.

[17] The film laminate according to any one of the above [1] to

[16] , which has a haze of 4.0% or less.

[18] The film laminate according to any one of the above [1] to

[17] , which has a total thickness of 19 to 800 μm.

[19] The film laminate according to any one of the above [1] to

[18] , wherein the polyester layer (X) has a total thickness of 9 to 300 μm.

[20] The film laminate according to any one of the above [1] to

[19] , wherein the resin layer (Y) has a thickness of 9 to 300 μm.

[21] The film laminate according to any one of the above [1] to

[20] , which is for use in a high-speed communication circuit.

[22] The film laminate according to

[21] above, which is used for a transparent antenna film.

[23] The film laminate according to

[22] above, which is used as an outdoor transparent antenna film. [Effects of the Invention]

[0016] The film laminate of the present invention has excellent low dielectric properties and is therefore compatible with high-speed communications. Furthermore, the film laminate of the present invention has excellent transparency and is therefore particularly suitable as a transparent antenna film member. Furthermore, the film laminate has a light transmittance of 20% or less at 380 nm and excellent ultraviolet absorption performance, making it suitable for outdoor use. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a microstrip line. DETAILED DESCRIPTION OF THE INVENTION

[0018] The inventors of the present invention considered that when a high-frequency electrical signal is passed through a circuit board such as one used in high-speed communication circuits, the electric field strength is greatest directly below the conductor wiring that makes up the circuit board, and therefore transmission loss can be efficiently reduced by providing low dielectric properties, particularly a low dielectric dissipation factor, for the film placed directly below the conductor wiring. Furthermore, by lowering the dielectric properties of the polyester layer (X) constituting the film laminate and thereby efficiently reducing transmission loss, it is thought possible to provide a film laminate having a highly versatile polyester layer (X) without compromising the excellent heat resistance, weather resistance, mechanical strength, and cost performance that polyester films, such as polyethylene terephthalate films, possess. The present invention will be described in detail below, but the content of the present invention is not limited to the embodiments described below.

[0019] The film laminate of the present invention comprises a polyester layer (X) and a resin layer (Y). <<Polyester layer (X)>> The polyester layer (X) constituting the film laminate of the present invention (hereinafter also referred to as "the polyester layer (X)") is a laminated polyester film having two or more polyester layers, and at least one surface layer has a layer A containing polycyclohexylene dimethylene terephthalate having terephthalic acid units as the dicarboxylic acid component (a-1) and 1,4-cyclohexanedimethanol units as the diol component (a-2). The thickness of the layer A is preferably 10 to 70% of the total thickness of the polyester layer (X), and the dielectric loss tangent at 28 GHz is preferably 0.0060 or less. The "surface layer" of the polyester layer (X) means the layer disposed on the outermost side of the polyester layer (X) having two or more polyester layers. The polyester layer (X) is a laminated film in which two or more polyester layers are laminated, but is distinguished from the film laminate of the present invention, which has a configuration in which the polyester layer (X) and the resin layer (Y) are laminated.

[0020] In the polyester layer (X), the number of laminated polyester layers is preferably 10 or less. If it is 10 or less, the thickness of each layer is sufficient, so that lamination during film formation is sufficient, flow marks and the like are unlikely to occur, and film quality is sufficiently maintained. Among these, from the viewpoint of reducing production costs, 2 to 3 layers is most preferred.

[0021] The polyester layer (X) has two or more polyester layers, and at least one of the polyester layers has, as a surface layer, at least one of the polyester layers, Layer A. For example, when a polyester layer other than Layer A is Layer B, the polyester layer (X) may have layers other than Layer A and Layer B. However, from the viewpoints of film-forming properties and interlayer adhesion, it is preferable that the polyester layer (X) is composed of only Layer A and Layer B.

[0022] Furthermore, for the purpose of efficiently reducing transmission loss, the polyester layer (X) may have a two-layer structure of Layer A / Layer B, but when emphasis is placed on versatility of the equipment, a three-layer structure of Layer A / Layer B / Layer A or Layer A / Layer B / Layer B is preferred.

[0023] Each polyester layer constituting the polyester layer (X) will be described in detail below. As an example of the embodiment according to the present invention, a polyester layer on at least one surface layer is designated as Layer A, and a polyester layer other than Layer A is designated as Layer B, and the polyester layer (X) is composed only of Layer A and Layer B. Layer A and Layer B may be made of the same polyester or different polyesters.

[0024] <Layer A> Layer A is a polyester layer for imparting low dielectric properties to the polyester layer (X), and preferably has a dielectric loss tangent of 0.0060 or less at 28 GHz. If the dielectric loss tangent of Layer A is 0.0060 or less, Po This can reduce the dielectric loss tangent of the entire polyester layer (X), thereby achieving a sufficient effect of reducing transmission loss. From the above viewpoints, the dielectric loss tangent of Layer A is more preferably 0.0050 or less, even more preferably 0.0045 or less, and even more preferably 0.0040 or less. The lower limit is not particularly limited, but is 0.0010 or more. From the same viewpoint, the relative dielectric constant of Layer A at 28 GHz is preferably 3.0 or less, more preferably 2.9 or less, and even more preferably 2.8 or less. The lower limit is not particularly limited, but is at least 2.0. The dielectric loss tangent and relative dielectric constant of Layer A are values ​​measured by the method described in the examples.

[0025] The thickness of the layer A is preferably 10 to 70% of the total thickness of the polyester layer (X). If the thickness of the layer A is 10% or more, a sufficiently low dielectric property can be obtained. On the other hand, if the thickness of the layer A is 70% or less, the heat resistance, weather resistance, mechanical strength, etc. are sufficient, and the layer A is highly versatile and advantageous in terms of cost. From the viewpoint of achieving a good balance of heat resistance, weather resistance, mechanical strength, cost, etc., and versatility, the thickness of Layer A is more preferably 15 to 60%, and even more preferably 20 to 50%, of the total thickness of the polyester layer (X). The thickness of Layer A can be adjusted by the ratio of the discharge rate when the polyester raw material is extruded in producing the polyester layer (X). The thickness of Layer A can be determined by creating an obliquely cut surface of the film using SAICAS (registered trademark) and using a time-of-flight secondary ion mass spectrometer (TOF-SIMS) to determine the layer thickness from the ion peak intensity data.

[0026] The total thickness of the polyester layer (X) is preferably from 9 to 300 μm, more preferably from 12 to 300 μm, even more preferably from 30 to 250 μm, and even more preferably from 50 to 200 μm. If the total thickness is 9 μm or more, the film strength remains within a practical range, while if the total thickness is 300 μm or less, it can be easily incorporated into mobile devices and the like. The total thickness of the polyester layer (X) was determined by cutting out a roughly square sample piece with sides of 40 mm from the polyester layer (X), measuring the thickness at any five points on the film surface using a dial gauge with a graduation of 1 / 1000 mm, and calculating the average value.

[0027] As described above, Layer A is a polyester layer having low dielectric properties and can be formed using polyester having low dielectric properties. As polyesters with low dielectric properties, it is particularly preferable to use polyesters having a cyclic structure such as a naphthalene ring or a cyclohexane ring as the backbone. It is presumed that the mechanism by which the cyclic structure described above provides excellent low dielectric properties is that the stacking of the cyclic structures can suppress dipole motion, thereby achieving a low dielectric loss tangent. In the present invention, Layer A is required to contain polycyclohexylene dimethylene terephthalate having terephthalic acid units as the dicarboxylic acid component (a-1) and 1,4-cyclohexanedimethanol units as the diol component (a-2). As described above, the polycyclohexylene dimethylene terephthalate has excellent low dielectric properties due to the presence of a cyclohexane ring structure. The polycyclohexylene dimethylene terephthalate contained in Layer A may further contain a unit having a naphthalene ring as its skeleton, or may further contain a polyester having low dielectric properties and a cyclic structure such as a naphthalene ring or cyclohexane ring as its skeleton.

[0028] Examples of the polyester having a naphthalene ring include polyesters containing, as a dicarboxylic acid component, 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, or the like. The dicarboxylic acid component of the polyester having a naphthalene ring is preferably the main component of the dicarboxylic acid component constituting the polyester. The term "main component" refers to the component that is contained in the greatest proportion among all dicarboxylic acid components constituting the polyester, and preferably refers to a component that accounts for 50 mol % or more of all dicarboxylic acid components, and more preferably 70 mol % or more of all dicarboxylic acid components. However, the polyester having a naphthalene ring is not limited to the above, and for example, the diol component may have a naphthalene ring.

[0029] Examples of polyesters having a cyclohexane ring include polyesters containing 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, etc. as a diol component. The diol component of the polyester having a cyclohexane ring is preferably a main component of the diol component constituting the polyester. The term "main component" refers to the component that is contained in the greatest proportion among all diol components constituting the polyester, and preferably refers to a component that accounts for 50 mol % or more of all diol components, and more preferably 70 mol % or more of all diol components. However, the polyester having a cyclohexane ring is not limited to the above, and for example, the dicarboxylic acid component may have a cyclohexane ring.

[0030] As described above, Layer A is required to contain polycyclohexylene dimethylene terephthalate having terephthalic acid units as the dicarboxylic acid component (a-1) and 1,4-cyclohexanedimethanol units as the diol component (a-2). By containing polycyclohexylene dimethylene terephthalate, Layer A can have excellent low dielectric properties and can improve the relative adhesion with Layer B described below. From the viewpoint of improving stretchability, it is preferable that the polycyclohexylene dimethylene terephthalate further contains isophthalic acid units as the dicarboxylic acid component (a-1). Furthermore, since Layer A contains the polycyclohexylene dimethylene terephthalate, it is also effective in suppressing the decrease in visibility caused by whitening of the film appearance due to precipitation and crystallization of oligomers.

[0031] From the viewpoint of interlayer adhesion with Layer B, it is more preferable that the dicarboxylic acid component (a-1) contains terephthalic acid units in an amount of 50 mol % or more, even more preferably 60 mol % or more, particularly preferably 70 mol % or more, and particularly preferably 80 mol % or more of the dicarboxylic acid component is terephthalic acid units. From the viewpoint of stretchability, the dicarboxylic acid component (a-1) preferably further contains 3 mol% or more of isophthalic acid units, more preferably 5 mol% or more, and even more preferably 8 mol% or more. From the viewpoint of crystallinity, the upper limit of the isophthalic acid unit content is preferably 25 mol% or less, more preferably 20 mol% or less.

[0032] The polycyclohexylene dimethylene terephthalate may contain a dicarboxylic acid component other than terephthalic acid and isophthalic acid as a structural unit. Examples of the dicarboxylic acid component (a-1) other than terephthalic acid and isophthalic acid include aromatic dicarboxylic acids such as phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,5-furandicarboxylic acid, 2,4-furandicarboxylic acid, 3,4-furandicarboxylic acid, benzophenonedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 3,3'-diphenyldicarboxylic acid, and 4,4'-diphenyletherdicarboxylic acid; and aliphatic dicarboxylic acids such as cyclohexanedicarboxylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. Among these, 2,5-furandicarboxylic acid, 2,4-furandicarboxylic acid, and 3,4-furandicarboxylic acid are preferred from the viewpoint of moldability. These dicarboxylic acid components can be used alone or in combination of two or more. The content of the dicarboxylic acid components other than terephthalic acid and isophthalic acid is preferably 10 mol % or less of the total dicarboxylic acid components including terephthalic acid and isophthalic acid.

[0033] Furthermore, from the viewpoint of heat resistance and stretching processability, it is more preferable that the diol component (a-2) contains 80 mol% or more of 1,4-cyclohexanedimethanol units, even more preferably 90 mol% or more, particularly preferably 95 mol% or more, and particularly preferably all (100 mol%) of the diol component (a-2) is 1,4-cyclohexanedimethanol units.

[0034] Examples of the diol component (a-2) other than 1,4-cyclohexanedimethanol that constitutes the polycyclohexylene dimethylene terephthalate include 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, ethylene glycol, diethylene glycol, triethylene glycol, polyalkylene glycol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, hydroquinone, bisphenol, spiroglycol, 2,2,4,4-tetramethylcyclobutane-1,3-diol, and isosorbide. Among these, ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,3-cyclohexanedimethanol are preferred from the viewpoint of moldability. These diol components can be used alone or in combination of two or more. The content of the diol components other than 1,4-cyclohexanedimethanol is preferably 10 mol % or less of the total diol components including 1,4-cyclohexanedimethanol.

[0035] The polyester polymerization catalyst is not particularly limited, and any conventionally known compound can be used, such as a titanium compound, a germanium compound, an antimony compound, a manganese compound, an aluminum compound, a magnesium compound, and a calcium compound.

[0036] In order to suppress the amount of precipitation of oligomer components, the film may be produced using a polyester having a low content of oligomer components as the raw material. As a method for producing a polyester having a low content of oligomer components, various known methods can be used, such as a method in which solid-state polymerization is carried out after the polyester is produced. Alternatively, the polyester may be obtained by carrying out an esterification or transesterification reaction, followed by melt polycondensation at a higher reaction temperature under reduced pressure.

[0037] Furthermore, Layer A may contain resins other than polyester as long as the effects of the present invention are not impaired. Examples of the other resins include polystyrene-based resins, polyvinyl chloride-based resins, polyvinylidene chloride-based resins, chlorinated polyethylene-based resins, polylactic acid-based resins, polybutylene succinate-based resins, polycarbonate-based resins, polyamide-based resins (including aramid-based resins), polyacetal-based resins, acrylic-based resins, ethylene-vinyl acetate copolymers, polymethylpentene-based resins, polyvinyl alcohol-based resins, cyclic olefin-based resins, polyacrylonitrile-based resins, polyethylene oxide-based resins, cellulose-based resins, polyimide-based resins, polyurethane-based resins, polyphenylene sulfide-based resins, polyphenylene ether-based resins, polyvinyl acetal-based resins, polybutadiene-based resins, polybutene-based resins, polyamide-imide-based resins, polyamide bismaleimide-based resins, polyetherimide-based resins, polyether ether ketone-based resins, polyether ketone-based resins, polyethersulfone-based resins, polyketone-based resins, polysulfone-based resins, and fluorine-based resins.

[0038] Layer A may contain particles primarily for the purposes of imparting lubricity and preventing scratches during each process. The type of particles is not particularly limited as long as they are capable of imparting lubricity, and specific examples include inorganic particles such as silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, and titanium oxide, and organic particles such as acrylic resin, styrene resin, urea resin, phenolic resin, epoxy resin, and benzoguanamine resin. Furthermore, precipitated particles obtained by precipitating and finely dispersing a part of a metal compound such as a catalyst during the polyester production process can also be used.

[0039] On the other hand, the shape of the particles to be used is not particularly limited, and any of spherical, blocky, rod-like, flat, etc. may be used. There are also no particular limitations on the hardness, specific gravity, color, etc. These particles may be used alone or in combination of two or more types as required.

[0040] The average particle size of the particles used is usually preferably 5 μm or less, more preferably in the range of 0.01 to 3 μm. If the particle size is 5 μm or less, the surface roughness of the film will not be too rough, and problems will not occur when various surface functional layers are formed in subsequent processes. In addition, the transparency of the film will be sufficient, which is preferable. The average particle size of the particles is calculated from the particle size (d50) at an integrated volume fraction of 50% in the equivalent spherical distribution measured using a centrifugal sedimentation particle size distribution measuring device.

[0041] Furthermore, the particle content in Layer A is usually preferably less than 5% by mass, and more preferably in the range of 0.0003 to 3% by mass. If there are no particles or only a small amount of particles, the film will be highly transparent and will be good in terms of transparency, but the slipperiness may be insufficient, so it may be necessary to take measures such as adding particles to the coating layer to improve the slipperiness. On the other hand, if the particle content is less than 5% by mass, the film will have good transparency.

[0042] There are no particular limitations on the method for adding particles to Layer A, and any conventionally known method can be used. For example, particles can be added at any stage in the production of the polyester constituting each layer, but it is preferable to add them after the completion of the esterification or transesterification reaction.

[0043] In addition to the above-mentioned particles, Layer A may contain conventionally known additives such as ultraviolet absorbers, antioxidants, antistatic agents, heat stabilizers, lubricants, dyes, and pigments, if necessary.

[0044] <Layer B> The polyester constituting Layer B is not particularly limited, and examples thereof include those composed of a dicarboxylic acid component (b-1) and a diol component (b-2) as shown below. Examples of the dicarboxylic acid component (b-1) include terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 4,4'-diphenyldicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2-potassium sulfoterephthalic acid, 5-sodium sulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid, succinic acid, trimellitic acid, trimesic acid, pyromellitic acid, trimellitic anhydride, phthalic anhydride, trimellitic acid monopotassium salt, and ester-forming derivatives thereof.

[0045] Examples of the diol component (b-2) include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,5-pentanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol, bisphenol A-ethylene glycol adduct, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polytetramethylene oxide glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, sodium dimethylolethylsulfonate, and potassium dimethylolpropionate. One or more compounds may be appropriately selected from the above compounds and subjected to a conventional polycondensation reaction to synthesize a polyester.

[0046] The polyester constituting Layer B may be the same as or different from the polyester constituting Layer A.

[0047] Among the above polyesters, from the viewpoints of improving versatility and a balance between heat resistance, weather resistance, mechanical strength, cost, etc., Layer B preferably contains polyethylene terephthalate having terephthalic acid units as the dicarboxylic acid component (b-1) and ethylene glycol units as the diol component (b-2). From the viewpoint of crystallinity and heat resistance, it is more preferable that the dicarboxylic acid component (b-1) contains terephthalic acid units in an amount of 60 mol% or more, even more preferably 80 mol% or more, particularly preferably 90 mol% or more, and particularly preferably all (100 mol%) of the dicarboxylic acid component (b-1) is terephthalic acid units. From the same viewpoint, it is more preferable that the diol component (b-2) contains 60 mol% or more of ethylene glycol units, even more preferably 80 mol% or more, particularly preferably 90 mol% or more, and particularly preferably all (100 mol%) of the diol component (b-2) is ethylene glycol units.

[0048] The polyester polymerization catalyst is not particularly limited, and any conventionally known compound can be used, such as a titanium compound, a germanium compound, an antimony compound, a manganese compound, an aluminum compound, a magnesium compound, and a calcium compound.

[0049] As with Layer A, in order to suppress the amount of precipitation of oligomer components, the film of Layer B may be produced using a polyester with a low content of oligomer components as the raw material. As a method for producing a polyester with a low content of oligomer components, various known methods can be used, such as a method in which solid-state polymerization is carried out after the polyester is produced. Alternatively, the polyester may be obtained by carrying out an esterification or transesterification reaction, followed by melt polycondensation at a higher reaction temperature under reduced pressure. When the amount of oligomer precipitated on the surface of Layer A constituting the polyester layer (X) is smaller than the amount of oligomer precipitated on the surface of Layer B constituting the polyester layer (X), a three-layer structure of Layer A / Layer B / Layer A is preferable to a two-layer structure of Layer A / Layer B or a three-layer structure of Layer A / Layer B / Layer B from the viewpoint of suppressing a decrease in visibility.

[0050] Like Layer A, Layer B may also contain particles, ultraviolet absorbers, antioxidants, antistatic agents, heat stabilizers, lubricants, dyes, pigments, and the like.

[0051] <Method for producing polyester layer (X)> A method for producing the polyester layer (X) will be described below, however, the following description is an example of a method for producing the polyester layer (X), and the present invention is not limited to this method.

[0052] For example, when producing a biaxially stretched film as the polyester layer (X), a preferred method is to co-extrude the polyesters that are the raw materials for Layer A and Layer B as described above from dies using multiple extruders, and then cool and solidify them on a rotating cooling drum to obtain an unstretched laminate sheet. In this case, it is preferable to increase the adhesion between the laminate sheet and the rotating cooling drum to improve the flatness of the laminate sheet, and an electrostatic application adhesion method and / or a liquid application adhesion method are preferably used. In this way, an unstretched laminate sheet is obtained. The polyester raw material may be fed to the extruder in the form of pellets or the like after being appropriately dried. Particles, an ultraviolet absorber, and other additives may be appropriately blended into the pellets.

[0053] Next, the unstretched laminate sheet obtained by the above method is stretched in one direction using a roll or tenter type stretching machine. The stretching temperature is usually 70 to 120°C, more preferably 80 to 110°C, and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Next, the film is stretched in a direction perpendicular to the first-stage stretching direction, in which case the stretching temperature is usually 70 to 170°C and the stretch ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times.

[0054] The film is then heat-treated at a temperature of 180 to 270°C under tension or relaxation of 30% or less to obtain a biaxially stretched film. The stretching may be performed in one direction in two or more stages. In this case, it is preferable to perform the stretching so that the final stretch ratios in both directions are within the above ranges.

[0055] The polyester layer (X) can also be produced by a simultaneous biaxial stretching method, in which the unstretched sheet is simultaneously stretched and oriented in the longitudinal and transverse directions under a temperature controlled condition usually at 70 to 120°C, preferably 80 to 110°C, at a stretching ratio of 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times in terms of area. The film is then subsequently heat-treated at a temperature of 170 to 250°C under tension or relaxation of 30% or less to obtain a stretched and oriented film. Regarding the simultaneous biaxial stretching device employing the above-mentioned stretching method, any conventionally known stretching method such as a screw method, a pantograph method, or a linear drive method can be used.

[0056] The longitudinal direction (MD) of the film refers to the direction in which the film advances during the film production process, i.e., the winding direction of the film roll, and the transverse direction (TD) refers to the direction parallel to the film surface and perpendicular to the longitudinal direction, i.e., the direction parallel to the central axis of the roll when the film is rolled.

[0057] <Physical properties of polyester layer (X)> The dielectric loss tangent of the polyester layer (X) at 28 GHz is preferably 0.0060 or less. If the dielectric loss tangent is 0.0060 or less, a sufficient effect of reducing transmission loss can be obtained. From the above viewpoints, the dielectric loss tangent of the polyester layer (X) is more preferably 0.0058 or less, and even more preferably 0.0056 or less. The lower limit is not particularly limited, but is 0.0010 or more. If the dielectric loss tangent of the polyester layer (X) is within this range, the polyester layer (X) has good low dielectric properties and can be suitably used for high-speed communication circuits. The dielectric loss tangent can be adjusted by the polyesters used in Layer A and Layer B, and the film-forming and stretching conditions of the polyester layer (X).

[0058] The relative dielectric constant of the polyester layer (X) at 28 GHz is preferably 3.5 or less, more preferably 3.3 or less, and even more preferably 3.1 or less. The lower limit is not particularly limited, but is at least 2.0. If the relative dielectric constant of the polyester layer (X) is within this range, the polyester layer (X) has good low dielectric properties and can be suitably used for high-speed communication circuits. The dielectric loss tangent and relative dielectric constant of the polyester layer (X) are values ​​measured by the method described in the examples.

[0059] The haze of the polyester layer (X) is preferably 4.0% or less, more preferably 3.0% or less, even more preferably 2.5% or less, particularly preferably 2.0% or less, particularly preferably 1.5% or less, and most preferably 1.0% or less. The lower limit is not particularly limited, but is at least 0.1%. When the haze is within this range, it can be said that the polyester layer (X) has good transparency, and a film laminate having the polyester layer (X) can be suitably used particularly as a transparent antenna film. The haze is a value measured by the method described in the examples.

[0060] The heat shrinkage of the polyester layer (X) after heat treatment at 150°C for 30 minutes is preferably -5 to 5%, more preferably -3 to 3%, and even more preferably -2 to 2% in both the machine direction (MD) and the transverse direction (TD). If the heat shrinkage is within this range, the film will have sufficient flatness and heat resistance. The heat shrinkage is measured by the method described in the examples, with positive values ​​representing shrinkage and negative values ​​representing expansion.

[0061] The transmission loss reduction rate (%) of the polyester layer (X) was calculated as follows using the transmission loss (dB) obtained from the simulation described in the Examples. [Transmission loss reduction rate (%)] = (1 - [Transmission loss (dB) when using the polyester layer (X)] / [Transmission loss (dB) when using polyethylene terephthalate film)]) × 100 The transmission loss reduction rate is preferably 5% or more, more preferably 7% or more, and even more preferably 10% or more. The higher the transmission loss reduction rate, the better, but if it is 5% or more, it can be said that the transmission loss can be efficiently reduced by using a film laminate having the polyester layer (X) with low dielectric properties.

[0062] <<Resin layer (Y)>> The film laminate of the present invention has a resin layer (Y). Examples of the resin layer (Y) include resin films formed from polymers such as polyethylene, polypropylene, cycloolefin polymer (COP), polyester, polystyrene, acrylic resin, polycarbonate, polyurethane, triacetyl cellulose (TAC), polyvinyl chloride, polyethersulfone, polyamide, polyimide, and polyamideimide in the form of a film. Furthermore, as long as film formation is possible, mixtures of these materials (polymer blends) or composites of structural units (copolymers) may also be used.

[0063] Among the films exemplified above, polyester films are particularly preferred because of their excellent physical properties such as heat resistance, flatness, optical properties, and strength. The polyester films may be single-layer or multi-layer films (i.e., laminated films) having two or more layers with different properties. Polyester films are films whose main resin component is polyester. The polyester film may be a non-stretched film (sheet) or a stretched film. Among these, a stretched film stretched uniaxially or biaxially is preferred. Among these, a biaxially stretched film is more preferred from the viewpoint of balance of mechanical properties and flatness. Therefore, a biaxially stretched polyester film is even more preferred.

[0064] <UV absorber> The resin layer (Y) preferably contains an ultraviolet absorber. By containing an ultraviolet absorber, the resulting film laminate can be used outdoors. Furthermore, in the case of a multi-layer polyester film, it is preferable that the ultraviolet absorber is contained in at least one polyester layer. Even more preferably, from the viewpoint of preventing bleed-out of the ultraviolet absorber, the ultraviolet absorber is contained in the intermediate layer (the YB layer in the case of a YA / YB / YC structure, or the YA layer in the case of a YB / YA / YB structure). Examples of the ultraviolet absorber include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, triazine-based ultraviolet absorbers, salicylic acid-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, benzoxazine-based ultraviolet absorbers, etc. These ultraviolet absorbers can be used alone or in combination of two or more.

[0065] Examples of benzophenone-based ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-methoxy-5-sulfoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfoxytrihydridolate benzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxy-5-sodium sulfoxybenzophenone, bis(5-benzoyl-4-hydroxy-2-methoxyphenyl)methane, 2-hydroxy-4-n-dodecyloxybenzophenone, and 2-hydroxy-4-methoxy-2'-carboxybenzophenone.

[0066] Examples of benzotriazole-based ultraviolet absorbers include 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-5-tert-octylphenyl)benzotriazole, 2-(2-hydroxy-3,5-dicumylphenyl)phenylbenzotriazole, 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole, 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol], 2-(2-hydroxy-3,5-di-tert-butylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-tert- butylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3,5-di-tert-amylphenyl)benzotriazole, 2-(2-hydroxy-5-tert-octylphenyl)benzotriazole, 2-(2-hydroxy-5-tert-butylphenyl)benzotriazole, 2-(2-hydroxy-4-octoxyphenyl)benzotriazole, 2,2'-methylenebis(4-cumyl-6-benzotriazolephenyl), 2,2'-p-phenylenebis(1,3-benzoxazin-4-one, 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimidomethyl)-5-methylphenyl]benzotriazole, and the like.

[0067] Examples of triazine-based ultraviolet absorbers include 2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-ethoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-propoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-butoxyphenyl)-4,6-diphenyl-1,3,5-triazine, and 2-(2-hydroxy-4-hexyloxyphenyl)-4,6-diphenyl-1,3,5-triazine. Azine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-dodecyloxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-benzyloxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3-5-triazine, 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3 ,5-triazine, 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine, 2-[4-[(2-hydroxy-3-dodecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-[(2-hydroxy-3-tridecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-[ (2-hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-octyloxy-2-hydroxypropyloxy)-5-α-cumylphenyl]-s-triazine, 2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-nonyloxy-2-hydroxypropyloxy)-5-α-cumylphenyl]-s-triazine, 2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-decyloxy-2-hydroxypropyloxy)-5-α-cumylphenyl]-s-triazine, 2-(2-hydroxy-4-acryloyloxyethoxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, etc.

[0068] Examples of salicylic acid-based ultraviolet absorbers include phenyl salicylate, p-tert-butylphenyl salicylate, and p-octylphenyl salicylate. Examples of cyanoacrylate ultraviolet absorbers include 2-ethylhexyl-2-cyano-3,3'-diphenylacrylate, and ethyl-2-cyano-3,3'-diphenylacrylate. An example of a benzoxazine-based ultraviolet absorber is 2,2'-p-phenylenebis(1,3-benzoxazin-4-one).

[0069] Among these, from the viewpoint of effectively suppressing light from reaching the coating type polarizing element, benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and benzoxazine-based ultraviolet absorbers are preferred.

[0070] From the viewpoint of improving lightfastness reliability, the lower limit of the content of the ultraviolet absorber is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, per 100 parts by mass of the substrate film containing the ultraviolet absorber. On the other hand, the upper limit of the content of the ultraviolet absorber is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, even more preferably 10 parts by mass or less, particularly preferably 8 parts by mass or less, and most preferably 7 parts by mass or less, from the viewpoint of suppressing bleed-out and improving yellowing resistance.

[0071] The thickness of the resin layer (Y) is preferably from 9 to 300 μm, more preferably from 12 to 250 μm, and even more preferably from 25 to 125 μm.

[0072] <<Cured resin layer>> The film laminate of the present invention preferably has a cured resin layer (CFB) on at least one side of the polyester layer (X), more preferably in the order of resin layer (Y), polyester layer (X), and cured resin layer (CFB). The film laminate of the present invention also preferably has a cured resin layer (CFA) on the side of the polyester layer (X) opposite to the side on which the cured resin layer (CFB) is laminated, more preferably in the order of resin layer (Y), optional adhesive layer, cured resin layer (CFA), and polyester layer (X). In particular, the cured resin layer (CFB) is preferably provided for the purpose of improving adhesion to a metal layer (an optional layer, described below). At least one of the cured resin layer (CFA) and the cured resin layer (CFB), more preferably the cured resin layer (CFB), is preferably formed from a resin composition containing a crosslinker in an amount of 70% by mass or more relative to the non-volatile components. It is more preferable that both the cured resin layer (CFA) and the cured resin layer (CFB) are formed from a resin composition containing a crosslinking agent in an amount of 70% by mass or more relative to the non-volatile components. In addition, other layers may be present between the cured resin layer (CFB) and the polyester layer (X), between the polyester layer (X) and the cured resin layer (CFA), between the cured resin layer (CFA) and the adhesive layer, or between the adhesive layer and the resin layer (Y) in order to impart functionality such as further improving adhesion.

[0073] As the crosslinking agent, various known crosslinking agents can be used, and examples thereof include oxazoline compounds, melamine compounds, epoxy compounds, isocyanate compounds, carbodiimide compounds, and silane coupling compounds. Among these, when a metal layer is provided on a cured resin layer, oxazoline compounds are preferably used from the viewpoint of improving durable adhesion. Furthermore, from the viewpoints of preventing oligomer precipitation on the film surface due to heating and improving the durability of the cured resin layer, melamine compounds are preferably used.

[0074] (Oxazoline compounds) An oxazoline compound is a compound having an oxazoline group in the molecule. A polymer containing an oxazoline group is particularly preferred. The compound can be prepared by polymerizing an addition-polymerizable oxazoline group-containing monomer alone or with other monomers. Examples of the addition-polymerizable oxazoline group-containing monomer include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline. These monomers can be used alone or in combination. Among these, 2-isopropenyl-2-oxazoline is preferred because it is readily available industrially. The other monomer is not limited as long as it is copolymerizable with the addition-polymerizable oxazoline group-containing monomer, and examples thereof include (meth)acrylic acid esters such as alkyl(meth)acrylate (the alkyl group can be methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, 2-ethylhexyl, and cyclohexyl); unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrenesulfonic acid, and salts thereof (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.); unsaturated nitriles such as acrylonitrile and methacrylonitrile; (meth)acrylamide, N-alkyl(meth)acrylate, N-methyl-N ... Examples of suitable monomers include unsaturated amides such as t)acrylamide and N,N-dialkyl(meth)acrylamide (the alkyl group can be a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, a 2-ethylhexyl group, a cyclohexyl group, and the like); vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; halogen-containing α,β-unsaturated monomers such as vinyl chloride and vinylidene chloride; and α,β-unsaturated aromatic monomers such as styrene and α-methylstyrene, and one or more of these monomers can be used. From the viewpoint of improving the durability of the coating film, the amount of oxazoline groups in the oxazoline compound is preferably in the range of 0.5 to 10 mmol / g, more preferably 3 to 9 mmol / g, and even more preferably 5 to 8 mmol / g.

[0075] (melamine compounds) The melamine compound is a compound having a melamine skeleton, and examples thereof include alkylolated melamine derivatives, compounds obtained by reacting alkylolated melamine derivatives with alcohols to partially or completely etherify them, and mixtures thereof. Suitable alcohols for etherification include methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, and isobutanol. The melamine compound may be a monomer or a dimer or higher polymer, or a mixture thereof. Furthermore, melamine may be partially co-condensed with urea or the like, and a catalyst may be used to increase the reactivity of the melamine compound.

[0076] (epoxy compounds) Epoxy compounds are compounds having an epoxy group in the molecule, and examples thereof include condensation products of epichlorohydrin, ethylene glycol, polyethylene glycol, glycerin, polyglycerin, bisphenol A, etc. with a hydroxyl group or an amino group, polyepoxy compounds, diepoxy compounds, monoepoxy compounds, glycidylamine compounds, etc. Examples of polyepoxy compounds include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris(2-hydroxyethyl)isocyanate, glycerol polyglycidyl ether, and trimethylolpropane polyglycidyl ether. Examples of diepoxy compounds include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcinol diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and polytetramethylene glycol diglycidyl ether. Examples of monoepoxy compounds include allyl glycidyl ether, 2-ethylhexyl glycidyl ether, and phenyl glycidyl ether, and examples of glycidylamine compounds include N,N,N',N'-tetraglycidyl-m-xylylenediamine and 1,3-bis(N,N-diglycidylamino)cyclohexane.

[0077] (Isocyanate compounds) The isocyanate compound refers to a compound having an isocyanate or an isocyanate derivative structure, such as a blocked isocyanate. Examples of the isocyanate include aromatic isocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate; aliphatic isocyanates having an aromatic ring, such as α,α,α',α'-tetramethylxylylene diisocyanate; aliphatic isocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, and hexamethylene diisocyanate; and alicyclic isocyanates such as cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, methylenebis(4-cyclohexyl isocyanate), and isopropylidenedicyclohexyl diisocyanate. Further examples include polymers and derivatives of these isocyanates, such as biuretized products, isocyanurated products, urethodionated products, and carbodiimide-modified products. These may be used alone or in combination. Among the above isocyanates, aliphatic isocyanates or alicyclic isocyanates are more preferred than aromatic isocyanates in order to prevent yellowing due to ultraviolet rays.

[0078] When used in the form of a blocked isocyanate, examples of the blocking agent include bisulfites, phenolic compounds such as phenol, cresol, and ethylphenol; alcohol compounds such as propylene glycol monomethyl ether, ethylene glycol, benzyl alcohol, methanol, and ethanol; active methylene compounds such as methyl isobutanoylacetate, dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, and acetylacetone; mercaptan compounds such as butyl mercaptan and dodecyl mercaptan; lactam compounds such as ε-caprolactam and δ-valerolactam; amine compounds such as diphenylaniline, aniline, and ethyleneimine; acid amide compounds such as acetanilide and acetic acid amide; and oxime compounds such as formaldehyde, acetaldoxime, acetone oxime, methyl ethyl ketone oxime, and cyclohexanone oxime, and these may be used alone or in combination of two or more.

[0079] The isocyanate compound may be used alone or as a mixture or bond with various polymers. In order to improve the dispersibility and crosslinkability of the isocyanate compound, it is preferable to use a mixture or bond with a polyester resin or a urethane resin.

[0080] (Carbodiimide compounds) A carbodiimide compound is a compound having a carbodiimide structure, and is a compound having one or more carbodiimide structures in the molecule. For better adhesion, etc., a polycarbodiimide compound having two or more carbodiimide structures in the molecule is more preferred.

[0081] Carbodiimide compounds can be synthesized by conventionally known techniques, and generally involve the condensation reaction of a diisocyanate compound. The diisocyanate compound is not particularly limited, and either an aromatic or aliphatic diisocyanate can be used. Specific examples include tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl diisocyanate, and dicyclohexylmethane diisocyanate.

[0082] The content of carbodiimide groups contained in the carbodiimide compound, in terms of carbodiimide equivalent (weight [g] of the carbodiimide compound required to provide 1 mol of carbodiimide groups), is usually in the range of 100 to 1000, preferably 250 to 700, and more preferably 300 to 500. Use in the above range improves the durability of the coating film.

[0083] Furthermore, within the scope of the present invention, in order to improve the water solubility or water dispersibility of the polycarbodiimide compound, a surfactant may be added, or a hydrophilic monomer such as a polyalkylene oxide, a quaternary ammonium salt of a dialkylamino alcohol, or a hydroxyalkyl sulfonate may be added.

[0084] (Silane coupling compounds) A silane coupling compound is an organosilicon compound that contains an organic functional group and a hydrolyzable group such as an alkoxy group in one molecule. For example, epoxy group-containing compounds such as 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; vinyl group-containing compounds such as vinyltrimethoxysilane and vinyltriethoxysilane; styryl group-containing compounds such as p-styryltrimethoxysilane and p-styryltriethoxysilane; (meth)acrylic group-containing compounds such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane; 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and N-2-(aminoethyl)- Examples of suitable compounds include amino group-containing compounds such as 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltriethoxysilane; isocyanurate group-containing compounds such as tris(trimethoxysilylpropyl)isocyanurate and tris(triethoxysilylpropyl)isocyanurate; and mercapto group-containing compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropylmethyldiethoxysilane.

[0085] These crosslinking agents may be used alone or in combination of two or more. However, by using two or more crosslinking agents in combination, it is possible to improve the prevention of oligomer precipitation after heating. Furthermore, by using two or more crosslinking agents in combination, for example, when a film laminate further has a metal layer on the cured resin layer, it is possible to improve the adhesion between the cured resin layer and the metal layer. Among them, a combination of an oxazoline compound, which can improve the adhesion between the cured resin layer and the metal layer, and a melamine compound, which has good prevention of oligomer precipitation after heating, is particularly preferred.

[0086] Furthermore, when the present film laminate further has a metal layer on the cured resin layer, it is more preferable to combine three or more crosslinking agents to further improve the adhesion between the cured resin layer and the metal layer. When combining three or more crosslinking agents, it is suitable to select a melamine compound as one of the crosslinking agents. As the crosslinking agent to be combined with the melamine compound, an oxazoline compound and an epoxy compound, or a carbodiimide compound and an epoxy compound are more preferable.

[0087] The crosslinking agent is preferably present in an amount of 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, based on the total nonvolatile components in the resin composition forming at least one of the cured resin layers. A crosslinking agent content of 70% by mass or more based on the total nonvolatile components in the resin composition forming the cured resin layer is preferred because it provides good resistance to oligomer precipitation after heating, and when the film laminate further has a metal layer on the cured resin layer, it provides good adhesion between the cured resin layer and the metal layer. For both the cured resin layer (CFA) and the cured resin layer (CFB), the ratio of the crosslinking agent to the nonvolatile components in the resin composition forming the cured resin layer is preferably within the above range.

[0088] The resin composition may contain a binder resin to improve the appearance of the cured resin layer and to improve adhesion to a metal layer that may be formed on the cured resin layer, within the scope of the present invention. As the binder resin, any known binder resin can be used, but from the viewpoint of improving adhesion with layers provided on the cured resin layer, it is preferable to use polyester resin, acrylic resin, or urethane resin.

[0089] The resin composition may also contain particles for the purpose of preventing blocking and improving slippage. From the viewpoint of film transparency, the average particle size is preferably 1.0 μm or less, more preferably 0.5 μm or less, and even more preferably 0.2 μm or less. On the other hand, to more effectively improve slippage, the average particle size is preferably 0.01 μm or more, more preferably 0.03 μm or more, and particularly preferably in a range larger than the film thickness of the cured resin layer. Specific examples of particles include silica, alumina, kaolin, calcium carbonate, and organic particles.

[0090] Furthermore, within the scope of the present invention, the resin composition may be used in combination with a crosslinking catalyst, an antifoaming agent, a coatability improver, a thickener, an organic lubricant, an antistatic agent, an ultraviolet absorber, an antioxidant, a foaming agent, a dye, a pigment, or the like, as needed.

[0091] The thickness of the cured resin layer (after drying) is preferably 0.003 to 1.0 μm, more preferably 0.005 to 0.5 μm, and even more preferably 0.01 to 0.2 μm. If the thickness is 1.0 μm or less, the appearance and blocking resistance of the cured resin layer are sufficient. On the other hand, if the thickness is 0.003 μm or more, the amount of oligomer precipitated from the film is small, resulting in a good result.

[0092] In general, the resin composition is preferably diluted with water, an organic solvent, or a mixture thereof, and the cured resin layer may be formed by coating the diluted resin composition as a coating liquid on the surface of the polyester layer (X) and drying it.

[0093] In the present film laminate, the cured resin layer (CFB) may be formed in the following order: resin layer (Y), polyester layer (X), and cured resin layer (CFB) by coating at least one surface of the polyester layer (X) with the resin composition. Alternatively, the cured resin layer (CFA) and cured resin layer (CFB) may be formed on both surfaces of the polyester layer (X) by coating both surfaces of the polyester layer (X) with the resin composition. Methods for forming the cured resin layer include in-line coating and offline coating, with in-line coating being preferred. In-line coating is a method of coating within the polyester layer (X) production process; specifically, it is a method of coating at any stage between melt-extrusion of the raw polyester material, stretching, heat-setting, and winding up. Usually, the coating is applied to an unstretched laminate sheet obtained by melting and quenching, a stretched uniaxially stretched film, a biaxially stretched film before heat setting, or the polyester layer (X) after heat setting and before winding up. In particular, a method in which the coating is applied to a uniaxially stretched film stretched in the longitudinal direction (machine direction), and then the film is stretched in the width direction (transverse direction) is preferred.

[0094] <Physical properties of cured resin layer> When the film laminate of the present invention has a cured resin layer, it is also effective in preventing oligomer precipitation on the film surface due to heating. By reducing oligomer precipitation, it is possible to suppress the decrease in visibility caused by whitening of the film appearance due to oligomer precipitation. Furthermore, when the film laminate of the present invention further has a metal layer, reducing oligomer precipitation in the cured resin layer can improve adhesion to the metal layer. In the film laminate of the present invention, the amount of oligomer (ester cyclic trimer) precipitated on the surface of at least one of the cured resin layers is 0.50 mg / m 2 Preferably, it is 0.45 mg / m or less. 2 More preferably, it is 0.43 mg / m or less. 2 It is more preferable that the amount of oligomer precipitation is 0.50 mg / m or less. 2If the content is less than this, it is preferable because it prevents the deterioration of visibility due to whitening of the film appearance caused by precipitation and crystallization of oligomers on the surface, the occurrence of defects in post-processing, and contamination of the process and components. 2 That's all. The amount of oligomer precipitated on the surface of the cured resin layer can be adjusted by the polyester used and the layer structure of the polyester layer (X). The amount of precipitated oligomer is a value obtained by the method described in the Examples.

[0095] <<Adhesive layer>> The film laminate of the present invention preferably has an adhesive layer between the polyester layer (X) and the resin layer (Y). The adhesive composition constituting the adhesive layer (hereinafter referred to as "the adhesive composition") preferably contains a (meth)acrylic polymer (A), a polyfunctional (meth)acrylate (B), and a radical polymerization initiator (C).

[0096] <(Meth)acrylic polymer (A)> The (meth)acrylic polymer may be a homopolymer of alkyl(meth)acrylate, or a copolymer obtained by polymerizing a monomer component copolymerizable therewith. For example, the copolymer may be a copolymer of an alkyl(meth)acrylate (a1) having 4 to 18 carbon atoms in the side chain as the main component and a monomer component copolymerizable therewith. The above-mentioned main component means a component that has a significant effect on the properties of the (meth)acrylic polymer (A), and the content of the component is usually 30% by mass or more, preferably 35% by mass or more, of the total (meth)acrylic polymer (A). The (meth)acrylic polymer (A) may contain two or more (meth)acrylic polymers having different glass transition temperatures, from the viewpoint of ensuring processability, adhesive strength, stress relaxation property, heat resistance reliability, and moist heat haze resistance.

[0097] Examples of the alkyl(meth)acrylate (a1) having 4 to 18 carbon atoms in the side chain include linear alkyl(meth)acrylates such as n-butyl(meth)acrylate, pentyl(meth)acrylate, hexyl(meth)acrylate, heptyl(meth)acrylate, n-octyl(meth)acrylate, nonyl(meth)acrylate, decyl(meth)acrylate, undecyl(meth)acrylate, lauryl(meth)acrylate, tridecyl(meth)acrylate, tetradecyl(meth)acrylate, cetyl(meth)acrylate, and stearyl(meth)acrylate; isobutyl(meth)acrylate, sec-butyl(meth)acrylate, t-butyl(meth)acrylate; and isopentyl(meth)acrylate. Examples of the acrylates include branched alkyl (meth)acrylates such as butyl (meth)acrylate, neopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, and isostearyl (meth)acrylate, and alicyclic (meth)acrylates such as cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, 3,5,5-trimethylcyclohexane (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and isobornyl (meth)acrylate. These may be used alone or in combination of two or more.

[0098] From the viewpoint of improving stress relaxation properties and heat resistance reliability when formed into an adhesive sheet or adhesive layer, the content of the alkyl (meth)acrylate (a1) is preferably 3 mass% or more, more preferably 5 mass% or more, even more preferably 8 mass% or more, particularly preferably 10 mass% or more, and most preferably 12 mass% or more, based on the total components of the (meth)acrylic polymer (A). Furthermore, from the viewpoint of suppressing a decrease in adhesive strength, the content of the alkyl (meth)acrylate (a1) is preferably 80 mass % or less, more preferably 75 mass % or less, even more preferably 70 mass % or less, and particularly preferably 65 mass % or less, based on the total components of the (meth)acrylic polymer (A).

[0099] Examples of the monomer component copolymerizable with the alkyl (meth)acrylate (a1) having 4 to 18 carbon atoms in the side chain include a hydroxyl group-containing (meth)acrylate monomer (a2), a (meth)acrylate monomer or vinyl ester-based monomer (a3) ​​having 1 to 3 carbon atoms in the side chain, a functional group-containing ethylenically unsaturated monomer (a4), and other copolymerizable monomers (a5).

[0100] Examples of the hydroxyl group-containing monomer (a2) include hydroxyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate; caprolactone-modified monomers such as caprolactone-modified 2-hydroxyethyl (meth)acrylate; oxyalkylene-modified monomers such as diethylene glycol (meth)acrylate and polyethylene glycol (meth)acrylate; primary hydroxyl group-containing monomers such as 2-acryloyloxyethyl-2-hydroxyethyl phthalate; secondary hydroxyl group-containing monomers such as 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 3-chloro-2-hydroxypropyl (meth)acrylate; and tertiary hydroxyl group-containing monomers such as 2,2-dimethyl-2-hydroxyethyl (meth)acrylate. These can be used alone or in combination of two or more.

[0101] Among the above hydroxyl group-containing monomers (a2), primary hydroxyl group-containing monomers, particularly 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate, and especially 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred because they have an excellent balance between moist heat resistance and heat resistance.

[0102] From the viewpoint of improving moist heat resistance, the lower limit of the content of the hydroxyl group-containing monomer (a2) is usually 3 mass% or more, preferably 5 mass% or more, more preferably 8 mass% or more, even more preferably 10 mass% or more, and particularly preferably 12 mass% or more, based on the total components of the (meth)acrylic polymer (A). On the other hand, the upper limit of the content of the hydroxyl group-containing monomer (a2) is usually 60% by mass or less, preferably 45% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less, and particularly preferably 25% by mass or less, from the viewpoint of suppressing the self-crosslinking reaction of the pressure-sensitive adhesive composition and improving processability and heat resistance reliability.

[0103] Examples of the (meth)acrylate monomer or vinyl ester monomer (a3) ​​having 1 to 3 carbon atoms in the side chain include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, vinyl propionate, vinyl acetate, etc. These monomers (a3) ​​may be used alone or in combination of two or more. Of the above-mentioned components (a3), it is preferable to use methyl (meth)acrylate and ethyl (meth)acrylate from the viewpoint of improving cohesive strength when used as an adhesive.

[0104] When the component (a3) ​​is contained, the lower limit of its content is preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 10% by mass or more, based on the total components of the (meth)acrylic polymer (A), from the viewpoint of improving cohesive strength when used as a pressure-sensitive adhesive. Also, when the component (a3) ​​is contained, the upper limit of its content is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, based on the total components of the (meth)acrylic polymer (A), from the viewpoint of improving processability.

[0105] Examples of the functional group-containing ethylenically unsaturated monomer (a4) include carboxyl group-containing monomers, nitrogen atom-containing functional group-containing monomers, acetoacetyl group-containing monomers, isocyanate group-containing monomers, and glycidyl group-containing monomers. Among these, functional group-containing monomers having a nitrogen atom are preferred in terms of imparting cohesive strength and crosslinking-promoting action, more preferably amino group-containing monomers and amide group-containing monomers, and even more preferably amino group-containing monomers. Examples of carboxyl group-containing monomers include (meth)acrylic acid, carboxylethyl (meth)acrylate, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 2-(meth)acryloyloxypropyl hexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxypropyl phthalic acid, 2-(meth)acryloyloxyethyl maleic acid, 2-(meth)acryloyloxypropyl maleic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxypropyl succinic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, monomethyl maleate, and monomethyl itaconate.

[0106] Examples of the amino group-containing monomer include primary amino group-containing (meth)acrylates such as aminomethyl (meth)acrylate and aminoethyl (meth)acrylate; secondary amino group-containing (meth)acrylates such as t-butylaminoethyl (meth)acrylate and t-butylaminopropyl (meth)acrylate; and tertiary amino group-containing (meth)acrylates such as ethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, diethylaminopropyl (meth)acrylate, and dimethylaminopropylacrylamide.

[0107] Examples of the amide group-containing monomer include (meth)acrylamide; N-alkyl(meth)acrylamides such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, Nn-butyl(meth)acrylamide, diacetone(meth)acrylamide, and N,N'-methylenebis(meth)acrylamide; N,N-dialkyl(meth)acrylamides such as N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-ethylmethylacrylamide, and N,N-diallyl(meth)acrylamide; hydroxyalkyl(meth)acrylamides such as N-hydroxymethyl(meth)acrylamide and N-hydroxyethyl(meth)acrylamide; and alkoxyalkyl(meth)acrylamides such as N-methoxymethyl(meth)acrylamide and N-(n-butoxymethyl)(meth)acrylamide.

[0108] Examples of the acetoacetyl group-containing monomer include 2-(acetoacetoxy)ethyl (meth)acrylate and allyl acetoacetate.

[0109] Examples of the isocyanate group-containing monomer include 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, and alkylene oxide adducts thereof. The isocyanate group may be protected with a blocking agent such as methyl ethyl ketone oxime, 3,5-dimethylpyrazole, 1,2,4-triazole, or diethyl malonate.

[0110] Examples of the glycidyl group-containing monomer include glycidyl (meth)acrylate and allyl glycidyl (meth)acrylate.

[0111] These functional group-containing ethylenically unsaturated monomers (a4) may be used alone or in combination of two or more.

[0112] From the viewpoint of improving the heat resistance and light resistance of the pressure-sensitive adhesive composition, the upper limit of the content of the functional group-containing ethylenically unsaturated monomer (a4) is preferably 30 mass % or less, more preferably 20 mass % or less, even more preferably 10 mass % or less, and particularly preferably 5 mass % or less, based on the total components of the (meth)acrylic polymer (A).

[0113] In the present invention, other copolymerizable monomers (a5) can be used as copolymerization components for the acrylic resin, if necessary.

[0114] Examples of the other copolymerizable monomers (a5) include aromatic (meth)acrylic acid ester monomers such as phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenyldiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, phenoxypolyethylene glycol-polypropylene glycol (meth)acrylate, and nonylphenol ethylene oxide adduct (meth)acrylate; 4-acryloyloxybenzophenone, 4-acryloyloxyethoxybenzophenone, 4-acryloyloxy-4'-methoxybenzophenone, 4-acryloyloxyethoxy-4'-methoxybenzophenone, 4-acryloyloxy-4'-bromobenzophenone, 4-acryloyloxyethoxy-4'-bromobenzophenone, 4-methacryloyloxybenzophenone, and 4-methacryloyloxybenzophenone. Examples of suitable vinyl monomers include (meth)acrylic acid ester monomers having a benzophenone structure, such as 4-hydroxyethoxybenzophenone, 4-methacryloyloxy-4'-methoxybenzophenone, 4-methacryloyloxyethoxy-4'-methoxybenzophenone, 4-methacryloyloxy-4'-bromobenzophenone, 4-methacryloyloxyethoxy-4'-bromobenzophenone, and mixtures thereof, as well as vinyl monomers such as acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyl stearate, vinyl chloride, vinylidene chloride, alkyl vinyl ethers, vinyl toluene, vinylpyridine, vinylpyrrolidone, dialkyl itaconate esters, dialkyl fumarate esters, allyl alcohol, acrylic chloride, methyl vinyl ketone, N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, and dimethylallyl vinyl ketone. These may be used alone or in combination of two or more.

[0115] The (meth)acrylic polymer (A) of the present invention may have a polymerizable carbon-carbon double bond group introduced into its side chain, which can enhance the crosslinking sensitivity of the pressure-sensitive adhesive composition, allowing the pressure-sensitive adhesive composition to be crosslinked by irradiation with lower-energy active energy rays, thereby imparting cohesive strength and heat resistance.

[0116] Examples of a method for introducing a polymerizable carbon-carbon double bond group into the side chain of the (meth)acrylic polymer (A) include a method in which a copolymer containing the above-mentioned hydroxyl group-containing monomer (a2) or functional group-containing ethylenically unsaturated monomer (a4) is prepared, and then a compound (a6) having a polymerizable carbon-carbon double bond group and a functional group reactive with these functional groups is subjected to a condensation or addition reaction while maintaining the activity of the polymerizable carbon-carbon double bond group. Combinations of these functional groups include epoxy groups (glycidyl groups) and carboxyl groups, amino groups and carboxyl groups, amino groups and isocyanate groups, epoxy groups (glycidyl groups) and amino groups, hydroxyl groups and epoxy groups, and hydroxyl groups and isocyanate groups. Among these combinations of functional groups, the combination of hydroxyl groups and isocyanate groups is preferred because of the ease of reaction control. Among these, a combination in which the copolymer has a hydroxyl group and the compound has an isocyanate group is preferred. Examples of the isocyanate compound having a polymerizable carbon-carbon double bond group include the above-mentioned 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, and alkylene oxide adducts thereof.

[0117] From the viewpoint of improving adhesiveness and stress relaxation properties, the amount of the compound (a6) added is preferably 10 parts or less, more preferably 8 parts or less, even more preferably 5 parts or less, and particularly preferably 3 parts or less, per 100 parts by mass of the (meth)acrylic polymer (A). From the viewpoint of obtaining a pressure-sensitive adhesive composition with high cohesive strength, the mass average molecular weight of the (meth)acrylic polymer (A) is preferably 100,000 or more, more preferably 300,000 or more, and even more preferably 500,000 or more. Furthermore, the upper limit of the mass average molecular weight of the (meth)acrylic polymer (A) is preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,000,000 or less, from the viewpoint of obtaining a pressure-sensitive adhesive composition having high fluidity and stress relaxation properties.

[0118] <Polyfunctional (meth)acrylate (B)> The polyfunctional (meth)acrylate (B) is a compound or composition that forms a crosslinked structure in the pressure-sensitive adhesive composition, and examples thereof include (meth)acrylic monomers and (meth)acrylic oligomers having two or more functional groups. By including the polyfunctional (meth)acrylate (B) in the present pressure-sensitive adhesive composition, the present pressure-sensitive adhesive composition forms a crosslinked structure, which can impart cohesive strength and durability to the present pressure-sensitive adhesive sheet.

[0119] Examples of the (meth)acrylic monomer include 1,4-butanediol di(meth)acrylate, glycerin di(meth)acrylate, neopentyl glycol di(meth)acrylate, glycerin glycidyl ether di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, tricyclodecane di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, bisphenol A polyethoxy di(meth)acrylate, bisphenol A poly(meth)acrylate), and bisphenol A poly(meth)acrylate. propoxydi(meth)acrylate, bisphenol F polyethoxydi(meth)acrylate, ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane trioxyethyl(meth)acrylate, ε-caprolactone-modified tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propoxylated pentaerythritol tri(meth)acrylate, ethoxylated pentaerythritol tri(meth)acrylate Pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, (tris(acryloxyethyl)isocyanurate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol Examples of the acrylate include thritol penta(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol penta(meth)acrylate, neopentyl glycol hydroxypivalate di(meth)acrylate, di(meth)acrylate of an ε-caprolactone adduct of neopentyl glycol hydroxypivalate, trimethylolpropane tri(meth)acrylate, trimethylolpropane polyethoxytri(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate. Among these, (meth)acrylic monomers are preferred from the viewpoint of imparting appropriate toughness to the cured product, and among these, polyfunctional (meth)acrylic monomers having an alkylene glycol skeleton, such as polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and polytetramethylene glycol di(meth)acrylate, are more preferred. The molecular weight of the (meth)acrylic monomer is preferably 200 or more, more preferably 300 or more, even more preferably 400 or more, and particularly preferably 500 or more, from the viewpoint of imparting appropriate flexibility to the cured product.

[0120] Examples of the (meth)acrylic oligomer include polyfunctional (meth)acrylic oligomers such as polyester (meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, and polyether (meth)acrylate. Among these, urethane (meth)acrylate oligomers are preferred from the viewpoint of imparting appropriate toughness to the cured product. The molecular weight of the (meth)acrylic oligomer is preferably 3,000 or more, more preferably 5,000 or more, even more preferably 8,000 or more, and particularly preferably 10,000 or more, from the viewpoint of imparting appropriate flexibility to the cured product.

[0121] The content of the polyfunctional (meth)acrylate (B) is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 4 parts by mass or more, and particularly preferably 10 parts by mass or more, per 100 parts by mass of the (meth)acrylic polymer (A), from the viewpoint of imparting shape stability to the pressure-sensitive adhesive sheet and durability when formed into a laminate. The upper limit of the content by mass of the polyfunctional (meth)acrylate (B) is preferably 100 parts by mass or less, more preferably 60 parts by mass or less, even more preferably 40 parts by mass or less, and particularly preferably 30 parts by mass or less, per 100 parts by mass of the (meth)acrylic polymer (A), from the viewpoint of ensuring adhesiveness.

[0122] <Radical polymerization initiator (C)> The radical polymerization initiator may be any as long as it is capable of releasing a substance that initiates radical polymerization upon at least one of irradiation with active energy rays such as light and heating. Examples of thermal radical polymerization initiators include organic peroxides such as hydrogen peroxide and perbenzoic acid, and azo compounds such as azobisbutyronitrile.

[0123] Photoradical polymerization initiators are broadly classified into two types based on the radical generation mechanism: cleavage-type photoradical polymerization initiators, which can generate radicals by cleaving and decomposing the single bond of the photoradical polymerization initiator itself, and hydrogen abstraction-type photoradical polymerization initiators, which form an exciplex between the photoexcited initiator and the hydrogen donor in the system and can transfer hydrogen from the hydrogen donor.

[0124] Among these, cleavage-type photoradical polymerization initiators are preferred because they decompose into different compounds when they generate radicals upon irradiation with light, and once excited, they no longer function as a reaction initiator. Therefore, they do not remain as active species in the pressure-sensitive adhesive after the crosslinking reaction is complete, and there is no possibility of causing unexpected photodegradation or the like to the pressure-sensitive adhesive. On the other hand, hydrogen abstraction-type photoradical polymerization initiators not only maintain their function as reaction initiators even after multiple light irradiations, but also do not produce decomposition products, unlike cleavage-type photoradical polymerization initiators, during the radical-generating reaction caused by irradiation with active energy rays such as ultraviolet rays. Therefore, they are less likely to become volatile components after the reaction is completed, and are therefore useful in that they can reduce damage to the adherend.

[0125] When a photoradical polymerization initiator is used, it is preferable that the initiator be one that generates radicals when irradiated with light in a wavelength range of, for example, 380 nm to 700 nm, and serves as the starting point for the crosslinking reaction of the present pressure-sensitive adhesive composition.

[0126] Examples of the cleavage-type photoradical polymerization initiator include 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-(4-(2-hydroxyethoxy)phenyl)-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-[4-{4-(2-hydroxy-2-methyl-propionyl)benzyl}phenyl]-2-methyl-propan-1-one, oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone), phenylglyoxy Examples of suitable methyl benzoate include methyl benzoate, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl)-1-[4-(4-morpholinyl)phenyl]-1-butanone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide, and derivatives thereof. Among these, acylphosphine oxide photoinitiators such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide, and bis(2,6-dimethoxybenzoyl)2,4,4-trimethylpentylphosphine oxide are preferred, from the viewpoint of becoming decomposed products and losing color after the reaction.

[0127] Examples of the hydrogen abstraction type photoradical polymerization initiator include bis(2-phenyl-2-oxoacetic acid)oxybisethylene, phenylglyoxylic acid methyl ester, a mixture of oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]ethyl ester and oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]ethyl ester, thioxanthone, 2-chlorothioxanthone, 3-methylthioxanthone, 2,4-dimethylthioxanthone, anthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, camphorquinone, and derivatives thereof. Among these, any one or more selected from the group consisting of phenylglyoxylic acid methyl ester, oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]ethyl ester and a mixture of oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]ethyl ester are preferred.

[0128] The photoradical polymerization initiator is not limited to the substances listed above. Any one of the photoradical polymerization initiators listed above or its derivatives may be used, or two or more may be used in combination. A thermal radical polymerization initiator and a photoradical polymerization initiator may also be used in combination.

[0129] The content of the radical polymerization initiator (C) is not particularly limited, but from the viewpoint of sufficiently progressing the polymerization reaction and improving the shape stability of the pressure-sensitive adhesive sheet, it is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and particularly preferably 1.5 parts by mass or more, per 100 parts by mass of the (meth)acrylic polymer (A). Furthermore, from the viewpoint of ensuring adhesiveness, the upper limit of the content of the radical polymerization initiator (C) is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 6 parts by mass or less, and particularly preferably 4 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic polymer (A).

[0130] The pressure-sensitive adhesive composition can be diluted with an organic solvent, coated on a release film, and dried to form a pressure-sensitive adhesive sheet. When the film laminate of the present invention has a cured resin layer (CFA) between the polyester layer (X) and the resin layer (Y), the pressure-sensitive adhesive sheet can be laminated on the cured resin layer (CFA) and then exposed to light for use. When the pressure-sensitive adhesive composition is active energy ray-curable, after laminating a pressure-sensitive adhesive sheet on the cured resin layer (CFA) or laminating a resin layer (Y) on the pressure-sensitive adhesive sheet, the composition can be cured by irradiating with light, which will result in stronger adhesion between the cured resin layer (CFA) and the resin layer (Y), thereby improving the reliability of the laminate. From the viewpoints of suppressing damage to the film and controlling the reaction, ultraviolet light and visible light are preferred as the light source used. The irradiation time and irradiation means are not particularly limited, but it is preferable to irradiate the polyester layer (X) with light from the side opposite to the cured resin layer (CFA) side (the cured resin layer (CFB) side).

[0131] Furthermore, the irradiation energy, irradiation time, irradiation method, etc. of the active energy ray are not particularly limited as long as they can activate the initiator and polymerize the (meth)acrylate component.

[0132] The thickness of the adhesive layer is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and particularly preferably 20 μm or more, from the viewpoint of protecting the polyester layer (X), while the upper limit of the thickness is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less, from the viewpoint of contributing to the thinning of the film laminate. The adhesive layer preferably has a relative dielectric constant of 3.9 or less and has step absorbency. If the relative dielectric constant of the adhesive layer is 3.9 or less, the excellent low dielectric properties of the polyester layer (X) of the film laminate are not impaired, which is preferable. The relative dielectric constant of the adhesive layer is preferably 3.8 or less. The relative dielectric constant of the adhesive layer is a value measured by the method described in the examples.

[0133] (Method of attaching adhesive layer) As described above, the adhesive layer preferably has step-absorbency. When the film laminate of the present invention is to be bonded to a surface on which an antenna wiring is provided on a cured resin layer (CFA), for example, it is preferable to first cure the adhesive layer by heat treatment or the like. By subjecting the adhesive layer to primary curing, the adhesive layer can be made to conform sufficiently to the stepped portion of the antenna wiring. Furthermore, by crosslinking the adhesive layer to a degree that is not too flexible by primary curing, the adhesive layer can conform sufficiently to every corner of the antenna wiring without conforming to the stepped portion and generating bubbles, and stress due to the stepped portion can be alleviated. Furthermore, even if the portion in contact with the stepped portion is exposed to a high-temperature, high-humidity environment or a sudden temperature change, foaming or peeling at the bonding interface can be prevented. Furthermore, by further secondary curing after bonding, the desired adhesive strength can be achieved. As described above, by employing a two-stage curing method, it is possible to impart step absorbency to the adhesive layer itself.

[0134] <<Metal layer>> The film laminate of the present invention may have a metal layer on the cured resin layer (CFB), for example, in the order of a resin layer (Y), a polyester layer (X), a cured resin layer (CFB), and a metal layer. Note that other layers may be further present between the cured resin layer (CFB) and the metal layer. The metal layer is a layer containing a metal as a main component, which means that the metal accounts for 50% by mass or more of the metal layer, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more. Examples of metals that can be used include copper, copper alloys, silver, stainless steel, nickel, nickel alloys, aluminum, aluminum alloys, titanium, and titanium alloys. From the viewpoint of electromagnetic wave shielding properties, copper and silver are preferred, and from the viewpoint of pliability (flexibility), copper is more preferred.

[0135] From the viewpoint of maintaining the transparency of the film laminate, the metal layer is preferably patterned, for example, in a mesh shape or a wire shape.

[0136] The thickness of the metal layer is preferably 0.001 to 30 μm, more preferably 0.01 to 20 μm, particularly 0.01 to 15 μm, and even more preferably 0.01 to 10 μm. When the thickness of the metal layer is equal to or greater than the lower limit, electrical conductivity is sufficiently ensured, and when the thickness is equal to or less than the upper limit, visibility can be reduced when the metal layer is provided, which is preferable. The metal layer may be provided by vapor deposition or sputtering, or may be provided in the form of a metal foil, and can be appropriately selected depending on the purpose. The thickness of the metal layer can be measured by observing the cross section of a sample with an electron microscope.

[0137] <<Film laminate>> The film laminate of the present invention comprises a polyester layer (X) and a resin layer (Y). In addition to the polyester layer (X) and the resin layer (Y), the film laminate of the present invention preferably further comprises a cured resin layer (CFB), a cured resin layer (CFA), and / or an adhesive layer, and more preferably has a configuration in which the cured resin layer (CFB), the polyester layer (X), the cured resin layer (CFA), the adhesive layer, and the resin layer (Y) are laminated in this order. (Light transmittance) The film laminate of this embodiment must have a light transmittance of 20% or less at 380 nm. If the light transmittance of the film laminate at 380 nm exceeds 20%, it is not suitable for outdoor use. The light transmittance at 380 nm of the film laminate of this embodiment is more preferably 18% or less, and even more preferably 16% or less.

[0138] (Thickness of film laminate) As described above, the film laminate of the present invention, which comprises the polyester layer (X) and the resin layer (Y), and optionally further comprises a cured resin layer (CFB), a cured resin layer (CFA), and / or an adhesive layer, preferably has a total thickness of 19 to 800 μm. A total thickness of 19 μm or more of the film laminate is preferred because the strength is maintained within a practical range. A total thickness of 800 μm or less of the film laminate is preferred because it can be easily incorporated into mobile devices and the like. The total thickness of the film laminate of the present invention is more preferably 30 to 750 μm, even more preferably 50 to 700 μm, even more preferably 100 to 500 μm, and particularly preferably 200 to 400 μm.

[0139] (Haze) The film laminate of the present invention preferably has a haze value of 4.0% or less. If the haze value is 4.0% or less, the film laminate can have excellent transparency. The film laminate of the present invention has a haze value of more preferably 3.0% or less, even more preferably 2.5% or less, even more preferably 2.0% or less, particularly preferably 1.8% or less, and most preferably 1.6% or less.

[0140] <<Application>> The film laminate of the present invention has excellent low dielectric properties without impairing transparency. Therefore, it can be suitably used for high-speed communication circuits. Examples of high-speed communication circuit applications include FPCs (Flexible Printed Circuits), which are flexible circuit boards formed from a resin film and copper foil, and transparent antenna films in which invisible ultrafine metal mesh wiring is formed on a transparent film. In particular, it can be suitably used for transparent antenna films, which require high transparency. Furthermore, the film laminate of the present invention has low light transmittance at 380 nm and good ultraviolet absorption performance, and is therefore suitable as a transparent antenna film that can be used outdoors.

[0141] <<Explanation of terms, etc.>> In the present invention, the term "film" includes the term "sheet", and the term "sheet" includes the term "film". In the present invention, when it is stated that "X to Y" (X and Y are any numbers), unless otherwise specified, it means "X or more and Y or less", and also means "preferably larger than X" or "preferably smaller than Y". Furthermore, when it is stated that the amount is "X or more" (X is any number), it also means that the amount is "preferably greater than X" unless otherwise specified, and when it is stated that the amount is "Y or less" (Y is any number), it also means that the amount is "preferably smaller than Y" unless otherwise specified. [Example]

[0142] The present invention will now be described in more detail with reference to examples, although the present invention is not limited to the examples described below.

[0143] <Evaluation method> (1) Intrinsic viscosity of polyester 1 g of polyester was precisely weighed, dissolved in 100 ml of a mixed solvent of phenol / tetrachloroethane = 50 / 50 (mass ratio), and measured at 30°C.

[0144] (2) The dielectric loss tangent and relative permittivity of a laminate (hereinafter sometimes referred to as a polyester film with a cured resin layer) in which a cured resin layer (CFA), a polyester layer (X), and a cured resin layer (CFB) are laminated in this order, and the dielectric ratio of the adhesive layer The polyester films with cured resin layers used in the examples and comparative examples were measured for dielectric loss tangent and relative dielectric constant at a frequency of 28 GHz in accordance with JIS R1641:2007 using a dielectric constant measurement system manufactured by AET Corporation (cavity resonator (TE mode), control software, vector network analyzer MS46122B (manufactured by Anritsu Corporation)). The relative dielectric constant of the adhesive layer was also measured.

[0145] (3) Dielectric loss tangent and relative permittivity of layers A and B (polyester layer (X)) The raw materials for Layer A were fed into a small twin-screw extruder and melt-extruded at 300°C to obtain an unstretched sheet with a thickness of 200 μm. The unstretched sheet was stretched at 100°C by a ratio of 3.0 × 3.0 using a batch-type small biaxial stretching machine to obtain a biaxially stretched film sample. The dielectric loss tangent and relative permittivity of Layer A at a frequency of 28 GHz were measured for the obtained film sample using the same method as above. The results are shown in Table 1. For Layer B, a film sample was obtained in the same manner as for Layer A, and the dielectric loss tangent and relative permittivity at a frequency of 28 GHz were measured. The results are similarly shown in Table 1.

[0146] [Table 1]

[0147] (4) Haze of polyester layer (X) and film laminate Measurement was carried out in accordance with JIS K7136:2000 using a haze meter DH-2000 manufactured by Nippon Denshoku Industries Co., Ltd.

[0148] (5) Heat shrinkage rate (polyester layer (X)) A 1.5cm x 15cm sample film was heat-treated for 30 minutes in a hot air oven maintained at a specified temperature (150°C) under no tension, and the lengths of the sample film were measured before and after the treatment, and the elastic modulus was calculated using the following formula. Measurements were taken in both the machine direction (MD) and the cross direction (TD) of the film. Heat shrinkage rate (%) = {(sample length before heat treatment) - (sample length after heat treatment)} ÷ (sample length before heat treatment) × 100

[0149] (6) Transmission loss evaluation by simulation (polyester layer (X)) An electromagnetic field simulation was performed to determine the appropriate line width (50 Ω line width) and transmission loss (insertion loss, S21) for a microstrip line pattern on a film circuit board, which would result in a characteristic impedance of 50 Ω. As a simulation model, the thickness of the polyester film (substrate) was set to 125 μm. The relative permittivity and dielectric loss tangent at 28 GHz of the polyester layer (X) used in the simulation are as shown in Table 1. Also, a simulation model was prepared in which a metal layer (copper foil, thickness 18 μm, surface roughness (Rz) 1.0 μm, line length 100 mm) was laminated on a substrate made of a polyester layer (X). The electromagnetic field simulation was performed under the conditions of a characteristic impedance of 50 Ω and a frequency of 28 GHz.

[0150] 1 is a cross-sectional view showing an example of a microstrip line 10. The microstrip line 10 has a substrate 11, a microstrip line 12 made of a metal layer, and a ground plane 13 made of a metal layer.

[0151] (7) Amount of oligomer (ester cyclic trimer) precipitated on the surface of the cured resin layer due to heating For each of the cured resin layer (CFA) and cured resin layer (CFB) constituting the film laminates of the Examples and Comparative Examples, a sample measuring 300 mm in length and 225 mm in width was heat-treated for 120 minutes in a hot air oven maintained at a predetermined temperature (180°C). After the heat treatment, a box-shaped sample measuring 200 mm in length and 125 mm in width and with an open top was prepared, with the measurement surface facing inward. Next, 10 mL of DMF (dimethylformamide) was placed in the box-shaped container and allowed to stand for 3 minutes. The DMF was then recovered and fed to a liquid chromatograph (Shimadzu Corporation: LC-7A, mobile phase A: acetonitrile, mobile phase B: 2% aqueous acetic acid solution, column: Mitsubishi Chemical Corporation "MCI GEL ODS 1HU," column temperature: 40°C, flow rate: 1 mL / min, detection wavelength: 254 nm) to determine the amount of ester cyclic trimer in the DMF. This value was divided by the area of ​​the film that had come into contact with the DMF to determine the amount of oligomer (ester cyclic trimer) (mg / m) on the surface of the cured resin layer. 2 The amount of ester cyclic trimer in DMF was determined from the peak area ratio between the peak area of ​​the standard sample and the peak area of ​​the measured sample (absolute calibration curve method). The standard sample was prepared by accurately weighing a previously separated ester cyclic trimer and dissolving it in an accurately weighed amount of DMF. The amounts of surface oligomers in the cured resin layer (CFA) and the cured resin layer (CFB) are as follows: (CFA surface) 0.21 (mg / m 2 ) / (CFB surface)0.43(mg / m 2 )

[0152] (8) Light transmittance of film laminate at 380 nm The light transmittance in the wavelength region of 380 nm of the film laminates produced in the examples and comparative examples was measured using a spectrophotometer (manufactured by Shimadzu Corporation; instrument name "UV2450").

[0153] <Materials used> [Polyester raw materials] Raw material A: Polycyclohexylene dimethylene terephthalate (dicarboxylic acid component: terephthalic acid (TPA) / isophthalic acid (IPA) (molar ratio) = 92 / 8, diol component: 1,4-cyclohexanedimethanol (CHDM) 100 mol%) (intrinsic viscosity = 0.80 dL / g) Raw material B: homopolyethylene terephthalate (intrinsic viscosity = 0.64 dl / g) Raw material C: homopolyethylene terephthalate (intrinsic viscosity = 0.585 dl / g) Raw material D: Masterbatch containing homopolyethylene terephthalate and 0.7% by mass of silica particles with an average particle size of 3 μm (intrinsic viscosity = 0.590 dL / g) Raw material E: Masterbatch (intrinsic viscosity = 0.610 dL / g) containing homopolyethylene terephthalate and 10% by mass of ultraviolet absorber (Sun Chemical, Cyasorb UV-3638F).

[0154] [Cured resin layer] The following resin composition was used to form the cured resin layer. (A1): Hexamethoxymethylolmelamine (A2): Epocross (manufactured by Nippon Shokubai Co., Ltd.), an oxazoline compound, with an oxazoline group content of 7.7 mmol / g (A3): Polyglycerol polyglycidyl ether (B1): Silica particles with an average particle size of 0.07 μm The compositions of the coating solutions used in the examples are shown in Table 2.

[0155] [Table 2]

[0156] [Adhesive layer] [(Meth)acrylic polymer (A)] A copolymer of 65% by mass of 2-ethylhexyl acrylate (a1), 6% by mass of methyl acrylate (a3), 11% by mass of ethyl acrylate (a3), 13% by mass of 2-hydroxyethyl acrylate (a2), and 5% by mass of 4-hydroxybutyl acrylate (a2), and the Mw of the acrylic acid ester copolymer measured by GPC was 900,000.

[0157] [Multifunctional (meth)acrylate (B)] Polypropylene glycol #700 diacrylate (Shin-Nakamura Chemical Co., Ltd., APG-700)

[0158] [Radical initiator (C)] 2,4,6-trimethylbenzoyldiphenylphosphine oxide (IGM Resins, Omnirad TPO H)

[0159] [others] Solvent: Ethyl acetate Silane coupling agent: 3-glycidoxypropyltrimethoxysilane (Shin-Etsu Silicone, KBM-403) Rust inhibitor: 1,2,3-triazole

[0160] (Preparation of adhesive sheet) A pressure-sensitive adhesive resin composition was prepared by uniformly mixing 200 parts by mass of the (meth)acrylic polymer (A) solution (dilution solvent: ethyl acetate, solids concentration: 50% by mass), 25 parts by mass of the polyfunctional (meth)acrylate initiator (B), 3 parts by mass of the radical initiator (C), 0.3 parts by mass of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Silicones, KBM-403) as a silane coupling agent, 0.3 parts by mass of 1,2,3-triazole as a rust inhibitor, and 101 parts by mass of ethyl acetate. The pressure-sensitive adhesive composition was spread in a sheet form on a 100 μm thick silicone release-treated release film (Diafoil MRV (V04) manufactured by Mitsubishi Chemical Corporation) so that the thickness of the adhesive composition after solvent drying would be 100 μm.

[0161] Next, the sheet-shaped pressure-sensitive adhesive composition together with the release film was placed in a dryer heated to 95°C and held there for 10 minutes to volatilize the solvent contained in the pressure-sensitive adhesive composition. Furthermore, a silicone release-treated release film (Diafoil MRQ manufactured by Mitsubishi Chemical Corporation) having a thickness of 75 μm was laminated on the sheet-shaped pressure-sensitive adhesive composition from which the solvent had been dried to form a laminate, and the pressure-sensitive adhesive composition was irradiated through the release film with a high-pressure mercury lamp at a wavelength of 365 nm with an integrated irradiation dose of 1000 mJ / cm. 2 , the cumulative irradiation dose at a wavelength of 405 nm is 1400 mJ / cm 2 Thus, a pressure-sensitive adhesive sheet with release films (adhesive sheet thickness: 100 μm) was obtained in which release films were laminated on both the front and back sides.

[0162] (Resin layer (Y)) Biaxially oriented polyester film (Y1) (with UV absorber) Raw materials B and D were mixed in a mass ratio of 92:8 to form the surface layer raw materials, and raw materials B, C, and E were mixed in a mass ratio of 25:69:6 to form the middle layer raw materials. The mixed raw materials for the surface layer and the intermediate layer were each fed into separate twin-screw extruders, co-extruded at 280°C, and then cooled and solidified on a cooling roll set at 25°C to obtain an unstretched film with two types and three layers (surface layer / intermediate layer / surface layer). The unstretched film was then stretched 3.3 times in the machine direction (MD) at 85°C using a roll stretching machine. After preheating at 80°C in a tenter, it was stretched 3.6 times in the transverse direction (TD) at 110°C. Finally, it was heat-treated at 200°C to obtain a biaxially stretched polyester film (Y1) with a thickness of 50 μm (surface layers: 2.5 μm, middle layer: 45 μm).

[0163] Biaxially oriented polyester film (Y2) (without UV absorber) Raw materials B and D were mixed at a mass ratio of 91:9 to form the surface layer, and raw materials B and C were mixed at a mass ratio of 61:39 to form the intermediate layer. The mixed raw materials for the surface layer and the intermediate layer were each fed into separate twin-screw extruders, co-extruded at 280°C, and then cooled and solidified on a cooling roll set at 25°C to obtain an unstretched film with two types and three layers (surface layer / intermediate layer / surface layer). The unstretched film was then stretched 3.5 times in the machine direction (MD) at 85°C using a roll stretching machine. After preheating at 80°C in a tenter, it was stretched 4.6 times in the transverse direction (TD) at 124°C. Finally, it was heat-treated at 237°C to obtain a biaxially stretched polyester film (Y2) with a thickness of 50 μm (surface layers: 2.5 μm, middle layer: 45 μm).

[0164] (Polyester layer (X)) Raw material A was used as the raw material for Layer A, and raw material B was used as the raw material for Layer B. Raw material A for Layer A was used as the raw material for the surface layer, raw material B was used as the raw material for the middle layer, and raw material B was used as the raw material for the other surface layer, and each was separately fed into a twin-screw extruder, and Layer A was co-extruded at 290°C and Layer B at 280°C, and then cooled and solidified on a cooling roll set at 15°C, resulting in an unstretched laminate sheet with two types and three layers: Layer A / Layer B / Layer B. The unstretched laminate sheet was then stretched 3.0 times in the machine direction (MD) at 88°C using a roll stretching machine. The coating solution was then applied to the sheet so that the film thickness (after drying) was 0.04µm. The sheet was then preheated at 120°C in a tenter and stretched 3.7 times in the transverse direction (TD) at 130°C. Finally, a heat treatment was performed at 250°C to obtain a biaxially stretched polyester layer (X) with a cured resin layer having a thickness of 125µm (Layer A / Layer B / Layer B = 50 / 50 / 25 (µm)). The properties of the resulting polyester layer (X) with a cured resin layer were evaluated by the methods described above. The evaluation results are shown in Table 3.

[0165] In the method for producing the polyester layer (X), after stretching in the longitudinal direction (MD) and before stretching in the transverse direction (TD), a coating liquid of the resin composition for forming the cured resin layer described above was applied to both sides of a uniaxially stretched laminated polyester film so that the film thickness (after drying) would be 0.04 μm, and then the film was stretched in the transverse direction and heat-treated under the conditions described above, thereby obtaining a biaxially stretched laminated polyester film (polyester film with a cured resin layer) in which a cured resin layer (CFA) having a thickness (after drying) of 0.04 μm, the polyester layer (X), and a cured resin layer (CFB) having a thickness (after drying) of 0.04 μm were laminated in this order.

[0166] Example 1 The 75 μm thick release film (MRQ75) was peeled off from the prepared adhesive sheet with release film, and the adhesive sheet was attached to the cured resin layer (CFA) surface of the polyester film with a cured resin layer prepared as described above.

[0167] Furthermore, a 100 μm thick release film (MRV100 (V04)) was peeled off from the adhesive sheet laminated on the polyester layer (X) to form an adhesive layer, and then a biaxially oriented polyester film (Y1) was attached to the exposed surface of the adhesive layer to obtain a film laminate. The properties of the obtained film laminate were evaluated using the methods described above. The evaluation results are shown in Table 4.

[0168] (Comparative Example 1) A film laminate was obtained by the same production method as in Example 1, except that the biaxially oriented polyester film (Y1) used in Example 1 was changed to the biaxially oriented polyester film (Y2). The properties of the obtained film laminate were evaluated by the above-mentioned methods. The evaluation results are shown in Table 4 below.

[0169] [Table 3]

[0170] [Table 4]

[0171] The results of Example 1 and Comparative Example 1 show that the film laminate of the present invention has a low light transmittance at 380 nm, and therefore has good ultraviolet absorption performance, a low haze value, and high transparency. Furthermore, since the polyester layer (X) used as a constituent member has a high transmission loss reduction rate and is a film structure using polyethylene terephthalate, a general-purpose resin, a film laminate having such a polyester layer (X) is expected to have potential as a low-dielectric-characteristic film. Furthermore, since the amount of oligomer (mainly cyclic trimer derived from polyester film) precipitated from the surface of the cured resin layer constituting the film is low, the film laminate of the present invention has a low risk of foreign matter adhesion associated with the oligomer precipitation, good visibility, and can be used outdoors, making it suitable as a transparent antenna film member. [Industrial Applicability]

[0172] The film laminate of the present invention has ultraviolet absorption properties, high transparency, and high flex resistance. Furthermore, since the film laminate of the present invention has a polyester layer with excellent low dielectric properties and transparency, it can be used outdoors for high-speed communication circuits and is very useful as a transparent antenna film member. [Explanation of symbols]

[0173] 10 Microstrip Line 11 Circuit Board 12 Microstrip Line 13 Ground plane

Claims

1. A polyester layer (X) and a resin layer (Y), The light transmittance at a wavelength of 380 nm is 20% or less, The haze is 4.0 or less, the polyester layer (X) has a laminated structure of two or more layers, and has, as at least one surface layer, a layer A containing polycyclohexylene dimethylene terephthalate having terephthalic acid units as the dicarboxylic acid component (a-1) and 1,4-cyclohexanedimethanol units as the diol component (a-2); A film laminate, wherein the dielectric loss tangent of the layer A at 28 GHz is 0.0060 or less.

2. The film laminate according to claim 1 , further comprising an adhesive layer between the polyester layer (X) and the resin layer (Y).

3. The film laminate according to claim 2 , wherein the adhesive layer has a relative dielectric constant of 3.9 or less.

4. The film laminate according to claim 2 or 3, wherein the adhesive layer has a thickness of 1 to 200 μm.

5. The film laminate according to any one of claims 1 to 4, which has a cured resin layer (CFB) on at least one side of the polyester layer (X).

6. The film laminate according to claim 5 , further comprising a metal layer on the cured resin layer (CFB).

7. The film laminate of claim 6 , wherein the metal layer is patterned.

8. 8. The film laminate according to claim 6, wherein the metal layer is made of copper or silver.

9. The film laminate according to any one of claims 5 to 8, wherein the polyester layer (X) has a cured resin layer (CFA) on the side opposite to the side on which the cured resin layer (CFB) is laminated.

10. At least one of the cured resin layer (CFA) and the cured resin layer (CFB) is formed from a resin composition containing a crosslinking agent in an amount of 70% by mass or more relative to non-volatile components. The film laminate according to any one of claims 5 to 9.

11. The film laminate according to any one of claims 1 to 10, wherein the polycyclohexylene dimethylene terephthalate further has an isophthalic acid unit as the dicarboxylic acid component (a-1).

12. The film laminate according to any one of claims 1 to 11, wherein a layer other than the layer A in the polyester layer (X) contains polyethylene terephthalate.

13. The film laminate according to any one of claims 1 to 12, wherein the relative dielectric constant of Layer A at 28 GHz is 3.0 or less.

14. The film laminate according to any one of claims 1 to 13, wherein the resin layer (Y) is a polyester film.

15. The film laminate according to any one of claims 1 to 14, wherein the resin layer (Y) contains an ultraviolet absorber.

16. The film laminate according to any one of claims 1 to 15, having a total thickness of 19 to 800 µm.

17. The film laminate according to any one of claims 1 to 16, wherein the polyester layer (X) has a total thickness of 9 to 300 µm.

18. The film laminate according to any one of claims 1 to 17, wherein the resin layer (Y) has a thickness of 9 to 300 µm.

19. The film laminate according to any one of claims 1 to 18, which is used for high-speed communication circuits.

20. The film laminate according to claim 19, which is for use as a transparent antenna film.

21. The film laminate of claim 20, which is for use as an outdoor transparent antenna film.

Images