Resin composition and film

Abstract

The present invention provides: a resin composition (X) and a molded body and a film that contain the resin composition (X). Said resin composition (X) contains 50-95 mass parts of polybutylene terephthalate (A) and 5-50 mass parts of a 4-methyl-1-pentene∙α-olefin copolymer (B) satisfying the following requirement (B-a) (where the total of the polybutylene terephthalate (A) and the 4-methyl-1-pentene∙α-olefin copolymer (B) is 100 mass parts). Requirement (B-a): said 4-methyl-1-pentene∙α-olefin copolymer (B) is composed of 60-90 mol% of structural units (i) derived from 4-methyl-1-pentene and 10-40 mol% of structural units (ii) derived from a C2-4 α-olefin (where the total of structural units (i) and structural units (ii) is 100 mol %).

Description

Resin composition and film

[0001] The present invention relates to a resin composition and a film.

[0002] Flexible printed circuits (hereinafter sometimes referred to as "FPC") are highly reliable flexible printed wiring boards made using polyimide or polyester film as a base material, and have characteristics such as high wiring density, being lightweight, thin, and being bendable.

[0003] A typical FPC has a structure in which an adhesive layer is formed on a base film (e.g., a polyimide film), which is a thin insulating material, and a conductor foil is further laminated on top of that. In the printed circuit board manufacturing process, a substrate on which an electric circuit is formed and a coverlay that protects it are usually bonded using a thermosetting adhesive. When the electric circuit is provided on only one side of the substrate, the coverlay is bonded to only one side of the substrate. When the electric circuit is provided on both sides of the substrate or in multiple layers, the coverlay is bonded to both sides of the substrate. When bonding the coverlay, the substrate and the coverlay coated with a thermosetting adhesive are sandwiched between metal plates, and heat and pressure are applied via the metal plates. During this process, a release film is sandwiched between the metal plates and the coverlay to prevent adhesion between the metal plates and the coverlay.

[0004] In particular, when a release film is used in an FPC manufacturing process, a required property is that the release film can be easily peeled off from the printed circuit board after heat curing (i.e., releasability). As film materials having releasability, fluorine-based polymers such as polyvinyl fluoride, polytetrafluoroethylene, and tetrafluoroethylene-hexafluoropropylene copolymer, as well as polymers such as polymethylpentene and polybutylene terephthalate have been used to date.

[0005] Furthermore, printed circuit boards have terminals for electrical circuits formed for electrical connection with other components, and these terminals are exposed and not covered by a coverlay. The adhesive applied to the coverlay, which covers areas other than the terminals, may melt during bonding under heat and pressure. This can lead to the molten adhesive flowing into the terminals of the electrical circuit, forming an adhesive coating layer and causing poor electrical connection. The flow of adhesive into the terminals can be prevented by filling the exposed gaps not covered by the coverlay with a release film. In this case, the release film is required to conform to the unevenness (i.e., uneven shape) between the areas covered by the coverlay and the exposed areas not covered by the coverlay, such as the terminals. If the release film's conformability is insufficient, the adhesive may flow into the terminals. Therefore, to prevent the adhesive from flowing into the terminals, a release film for FPC manufacturing processes is required to conform to the unevenness (e.g., uneven shape) on the laminate of the electrical circuit substrate and the coverlay.

[0006] Furthermore, in the FPC manufacturing process, when the coverlay is bonded by heat and pressure press molding, the release film is subjected to large temperature changes in a relatively short period of time, which makes it easy for wrinkles to form on the surface of the release film. If wrinkles exist on the release film, the wrinkles in the release film may be transferred directly to the FPC, or the film may not be able to conform to unevenness, which may hinder the production of high-quality FPCs.

[0007] As an example of a release film that has an improved balance between stable releasability and tracking ability, Patent Document 1 discloses a release film that has a release layer containing a polyester resin on at least one surface, in which the crystallinity of the release layer is 10% or more and 50% or less, and the loss factor (tan δ) of the release layer at 150°C (measurement method: in accordance with JIS K7244, tensile mode, temperature rise rate 5°C / min, frequency 1 Hz) is 0.02 or more and less than 0.12. Furthermore, as an example of a release film that can suppress the occurrence of wrinkles while maintaining releasability, Patent Document 2 discloses a release film that is suitable for the production of flexible circuit boards, characterized in that the front and back surfaces are roughened, the ten-point average roughness Rz of the surface is 4 μm or more and 20 μm or less, and the thickness of the release layer that constitutes the back surface is 35 μm or more (however, this does not include the case where the ten-point average roughness Rz of the surface is 4 μm or more and 5 μm or less, and the thickness of the release layer that constitutes the back surface is 35 μm or more and 36 μm or less).

[0008] JP 2016-002730 A JP 2019-217780 A

[0009] In recent years, circuit boards have become increasingly miniaturized and thinner, increasing the requirements for release film properties. Furthermore, as the FPC manufacturing process speeds up, excessive stress can be applied when peeling off a release film during press molding. Patent Document 1 combines the measure of the crystallinity of the release layer with the measure of the loss coefficient (tan δ) of the release layer at 150°C to improve the balance between releasability and conformability. However, upon examining the release film of Patent Document 1, it was found that, because the resin materials used for the release layer and cushion layer are different, the heat shrinkage rates of each layer are likely to differ significantly under the heating temperature conditions of the FPC manufacturing process, resulting in poor dimensional stability of the release film. Therefore, there is a concern that the release film disclosed in Patent Document 1 may develop wrinkles on its surface after heating and pressure press molding, resulting in insufficient conformability, particularly to fine unevenness. Furthermore, wrinkles on the release film surface may be directly transferred to the FPC, potentially resulting in a high-quality FPC.

[0010] In the release film disclosed in Patent Document 2, releasability is achieved by roughening both the front and back surfaces, but because the resin materials used for the release layer and the intermediate layer are different, large differences in the thermal shrinkage rates of the layers are likely to occur under the heating temperature conditions of the FPC manufacturing process, and wrinkles may occur on the surface of the resulting release film. Furthermore, in recent years, circuit patterns on printed wiring boards have become increasingly finer, so if a release film with roughened surfaces on both the front and back surfaces as in Patent Document 2 is used, it may not be able to sufficiently conform to fine circuit patterns.

[0011] Furthermore, when polybutylene terephthalate is used as the main component of a film, the crystallization rate of polybutylene terephthalate is fast, which tends to slightly deteriorate the smoothness of the film surface. On the other hand, when polybutylene terephthalate is combined with other resins to form a polymer alloy, the resin film shrinks significantly in the width direction during T-die extrusion molding, which can easily cause the neck-in phenomenon in which the resin film narrows in width.

[0012] As a result of extensive research into solving the above problems, the present inventors have found that a film obtained from a resin composition (X) comprising 50 to 95 parts by mass of polybutylene terephthalate (A) and 5 to 50 parts by mass of a 4-methyl-1-pentene / α-olefin copolymer (B) satisfying specific requirements (where the total of the polybutylene terephthalate (A) and the 4-methyl-1-pentene / α-olefin copolymer (B) is 100 parts by mass), has excellent conformability to fine steps (e.g., uneven shapes) in an FPC, prevents adhesive from flowing out to terminal portions, and has excellent wrinkle suppression and releasability, which has led to the completion of the present invention.

[0013] The problem to be solved by one embodiment of the present invention is to provide a resin composition that provides excellent conformability and wrinkle suppression in the resulting molded article. The problem to be solved by another embodiment of the present invention is to provide a film that provides excellent conformability and wrinkle suppression.

[0014] Means for solving the above problems include the following aspects: <1> A resin composition (X) comprising 50 to 95 parts by mass of polybutylene terephthalate (A), and 5 to 50 parts by mass of a 4-methyl-1-pentene / α-olefin copolymer (B) that satisfies the following requirement (Ba-a) (provided that the total of the polybutylene terephthalate (A) and the 4-methyl-1-pentene / α-olefin copolymer (B) is 100 parts by mass); requirement (Ba-a): the resin composition is composed of 60 to 90 mol % of structural units (i) derived from 4-methyl-1-pentene and 10 to 40 mol % of structural units (ii) derived from an α-olefin having 2 to 4 carbon atoms (provided that the total of the structural units (i) and the structural units (ii) is 100 mol %). <2> Resin composition (X) according to <1>, wherein the content of at least one elastomer selected from the group consisting of a polyester-based elastomer (D) and a styrene-based elastomer (E) is 0 to 30 parts by mass per 100 parts by mass of the resin composition. <3> Resin composition (X) according to <1> or <2>, wherein the 4-methyl-1-pentene / α-olefin copolymer (B) further satisfies the following requirement (B-b): Requirement (B-b): The melting point (Tm) measured by differential scanning calorimetry (DSC) is not observed or is in the range of less than 160°C. <4> Resin composition (X) according to any one of <1> to <3>, wherein the 4-methyl-1-pentene / α-olefin copolymer (B) further satisfies the following requirement (B-e): Requirement (B-e): The intrinsic viscosity [η] measured in decalin solvent at 135°C is in the range of 0.8 to 3.0 dl / g. <5> The resin composition (X) according to any one of <1> to <4>, wherein the 4-methyl-1-pentene / α-olefin copolymer (B) further satisfies the following requirement (B-g): the molecular weight distribution (Mw / Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), measured by gel permeation chromatography (GPC), is in the range of 1.5 to 3.0. <6> The melt volume-flow rate (MVR) of the polybutylene terephthalate (A), measured in accordance with JIS K7210-1 (2014) at a temperature of 250°C and a load of 2.16 kgf, is in the range of 0.5 to 60 cm ３<7> The resin composition (X) according to any one of <1> to <5>, wherein the melt volume-flow rate (MVR) of the polybutylene terephthalate (A) measured in accordance with JIS K7210-1 (2014) at a temperature of 250°C and a load of 2.16 kgf is in the range of 15 to 50 cm ３ <8> The resin composition (X) according to any one of <1> to <6>, wherein the melt volume-flow rate (MVR) of the polybutylene terephthalate (A) measured in accordance with JIS K7210-1 (2014) at a temperature of 250°C and a load of 2.16 kgf is in the range of 25 to 40 cm ３ <9> The resin composition (X) according to any one of <1> to <8>, wherein the content of at least one elastomer selected from the group consisting of a polyester-based elastomer (D) and a styrene-based elastomer (E) is 5 to 15 parts by mass per 100 parts by mass of the resin composition. <10> A molded article comprising the resin composition (X) according to any one of <1> to <9>. <11> A film comprising the resin composition (X) according to any one of <1> to <9>. <12> The film according to <11>, which is a monolayer film. <13> The film according to <11> or <12>, wherein the critical surface tension at 23°C is 20 to 30 mN / m. <14> The film according to any one of <11> to <13>, wherein the storage modulus E' of the solid viscoelasticity at 180°C, measured under conditions of a tensile mode, a frequency of 1.0 Hz, a heating rate of 3°C / min, and a strain of 0.1%, is in the range of 10 to 90 MPa. <15> The film according to any one of <11> to <14>, wherein the maximum value of the loss tangent tanδ of the solid viscoelasticity at 20 to 35°C (tanδ peak value) is in the range of 0.02 to 0.30, measured under conditions of a tensile mode, a frequency of 1.0 Hz, a heating rate of 3°C / min, and a strain of 0.1%. <16> The film according to any one of <11> to <15>, which is a release film. <17> The film according to any one of <11> to <16>, which is a release film for use in a printed wiring board manufacturing process.

[0015] According to one embodiment of the present invention, there is provided a resin composition that provides a molded article having excellent conformability and wrinkle-resistance, and a film that provides excellent conformability and wrinkle-resistance.

[0016] Specific embodiments of the present invention will be described in detail below. The following description of the constituent elements may be based on a representative embodiment of the present invention, but the present invention is not limited to the following embodiment and can be implemented with appropriate modifications within the scope of the present invention.

[0017] In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​written before and after "to" as the lower and upper limits. In this specification, when referring to the amount of each component in a composition, if the composition contains multiple substances corresponding to each component, it means the total amount of multiple substances present in the composition, unless otherwise specified. In this specification, when "to" indicates a numerical range, it means that the units written before or after it indicate the same unit unless otherwise specified. In this specification, a combination of two or more preferred embodiments is a more preferred embodiment.

[0018] [Resin Composition (X)] Resin composition (X) according to the present invention comprises 50 to 95 parts by mass of polybutylene terephthalate (A) and 5 to 50 parts by mass of a 4-methyl-1-pentene / α-olefin copolymer (B) satisfying the following requirement (Ba) (provided that the total of the polybutylene terephthalate (A) and the 4-methyl-1-pentene / α-olefin copolymer (B) is 100 parts by mass). Because resin composition (X) has the above-described structure, the resulting molded article has excellent conformability and wrinkle suppression. The reason for this is not clear, but the following mechanism is presumed.

[0019] Resin composition (X) contains specific amounts of polybutylene terephthalate (A) and 4-methyl-1-pentene / α-olefin copolymer (B) that satisfies specific requirements. While polybutylene terephthalate (A) and copolymer (B) are resins with different polarities, it is believed that copolymer (B) is contained (dispersed) within polybutylene terephthalate (A) in the composition. Essentially, polybutylene terephthalate (A) and copolymer (B) have a sea-island structure in which polybutylene terephthalate (A) is the continuous phase and copolymer (B) is the dispersed phase. It is believed that if the dispersed phase of copolymer (B) is small, the stress relaxation properties characteristic of copolymer (B) are readily exhibited. Therefore, it is believed that the stress relaxation properties inherent to copolymer (B) are readily imparted. Therefore, films formed from resin composition (X) exhibit excellent conformability to uneven surfaces (e.g., uneven shapes) and excellent wrinkle suppression. Furthermore, when a molded article obtained from the resin composition (X) is used as a release film in the production of an FPC, it exhibits excellent conformability to fine unevenness on the FPC and can prevent the adhesive from leaking to the terminals. Each component of the resin composition (X) will be described in detail below.

[0020] <Polybutylene terephthalate (A)> The resin composition (X) contains polybutylene terephthalate (A). The polybutylene terephthalate (A) is not particularly limited as long as it has a skeleton containing structural units derived from 1,4-butanediol and structural units derived from terephthalic acid. The polybutylene terephthalate (A) may be polybutylene terephthalate (PBT) obtained by condensation polymerization of 1,4-butanediol and terephthalic acid, or may contain structural units other than the structural units derived from 1,4-butanediol and the structural units derived from terephthalic acid. Examples of polybutylene terephthalates containing other structural units include block copolymers of polybutylene terephthalate and aliphatic polyethers, and block copolymers of polybutylene terephthalate and aliphatic polyesters. Among these, the polybutylene terephthalate (A) is preferably a condensation polymer of 1,4-butanediol and terephthalic acid (i.e., polybutylene terephthalate alone), from the viewpoint of obtaining good dispersibility with the 4-methyl-1-pentene / α-olefin copolymer (B) described later and obtaining a molded product having an excellent balance of conformability, wrinkle suppression, mold releasability, etc.

[0021] The monomer constituting the polybutylene terephthalate (A) may be a monomer derived from a fossil fuel, a monomer derived from biomass, or a combination of a monomer derived from a fossil fuel and a monomer derived from biomass.

[0022] The upper limit of the melt volume flow rate (MVR) of the polybutylene terephthalate (A) is 40 cm from the viewpoint of film formability in film molding. ３ / 10 minutes or less is preferable, and 35 cm ３ / 10 minutes or less is more preferable, and 30 cm ３ The lower limit is preferably 0.5 cm / 10 minutes or less. ３ / 10 minutes or more is preferable, and 2 cm ３ / 10 minutes or more is more preferable, and 4 cm ３The MVR is determined by measuring at a temperature of 250°C and a load of 2.16 kgf in accordance with JIS K7210-1 (2014).

[0023] In addition, the upper limit of the melt volume flow rate (MVR) of the polybutylene terephthalate (A) is 60 cm from the viewpoint of reducing the critical surface tension. ３ / 10 minutes or less is preferable, and 50 cm ３ / 10 minutes or less is more preferable, and 40 cm ３ The lower limit is preferably 0.5 cm / 10 minutes or less. ３ / 10 minutes or more is preferable, and 2 cm ３ / 10 minutes or more is more preferable, and 4 cm ３ / 10 minutes or more is more preferable, and 15 cm ３ / 10 minutes or more is particularly preferable, and 25 cm ３ It is most preferable that the time is 10 minutes or more.

[0024] In addition, the upper limit of the melt volume flow rate (MVR) of the polybutylene terephthalate (A) is 60 cm from the viewpoint of improving the smoothness of the film surface. ３ / 10 minutes or less is preferable, and 50 cm ３ / 10 minutes or less is more preferable, and 40 cm ３ The lower limit is preferably 0.5 cm / 10 minutes or less. ３ / 10 minutes or more is preferable, and 2 cm ３ / 10 minutes or more is more preferable, and 4 cm ３ / 10 minutes or more is more preferable, and 15 cm ３ / 10 minutes or more is more preferable, and 25 cm ３ The melt volume flow rate (MVR) of the polybutylene terephthalate (A) is preferably 15 to 50 cm / min from the viewpoint of reducing the critical surface tension or improving the smoothness of the film surface. ３ / 10 minutes, more preferably 25 to 40 cm ３ / 10 minutes range.

[0025] From the viewpoint of film formability in film molding, the melting point (Tm) of the polybutylene terephthalate (A) is preferably 180 to 250° C., more preferably 200 to 240° C., and even more preferably 210 to 230° C. The melting point of the polybutylene terephthalate (A) can be determined by measuring the maximum temperature of the endothermic peak accompanying melting in a nitrogen gas flow at a heating rate of 10° C. / min using a differential scanning calorimeter (DSC), heating the sample to 300° C. for 5 minutes to melt it, and then quenching it with liquid nitrogen to obtain a 5 mg sample.

[0026] The polybutylene terephthalate (A) may be synthesized or may be a commercially available product, such as "NovaDuran (registered trademark)" manufactured by Mitsubishi Chemical Corporation, "Trecon (registered trademark)" manufactured by Toray Industries, Inc., "Planac (registered trademark)" manufactured by Toyobo Co., Ltd., or "Duranex (registered trademark)" manufactured by Polyplastics Co., Ltd.

[0027] The content of polybutylene terephthalate (A) is 50 to 95 parts by mass, preferably 52 to 94 parts by mass, more preferably 56 to 93 parts by mass, and even more preferably 58 to 92 parts by mass (however, the total of the polybutylene terephthalate (A) and the 4-methyl-1-pentene / α-olefin copolymer (B) described below is 100 parts by mass). The polybutylene terephthalate (A) may be used alone or in combination of two or more types.

[0028] <<4-methyl-1-pentene·α-olefin copolymer (B)>> The resin composition (X) of the present invention contains a 4-methyl-1-pentene·α-olefin copolymer (B) (hereinafter sometimes abbreviated as “copolymer (B)”) that satisfies the following requirement (Ba-a):

[0029] [Requirement (Ba)] Comprised of 60 to 90 mol % of structural units (i) derived from 4-methyl-1-pentene and 10 to 40 mol % of structural units (ii) derived from an α-olefin having 2 to 4 carbon atoms (provided that the total of structural units (i) and structural units (ii) is 100 mol %).

[0030] The content (mol %) of the structural units (i) and (ii) in the copolymer (B) was determined by carbon-13 nuclear magnetic resonance (hereinafter referred to as " １３ The specific measurement method is as described in the Examples below.

[0031] The content of the structural unit (i) is from 60 to 90 mol %, preferably from 65 to 89 mol %, more preferably from 68 to 88 mol %, and even more preferably from 70 to 87 mol %.

[0032] The content of the structural unit (i) in the copolymer (B) is preferably 60 mol% or more, since good dispersibility with the polybutylene terephthalate resin (A) can be obtained. Furthermore, when the content of the structural unit (i) is within the above range, the releasability of the polybutylene terephthalate (A) is not impaired, and the film obtained from the resin composition (X) also has excellent releasability.

[0033] The content of the structural unit (ii) is from 10 to 40 mol %, preferably from 11 to 35 mol %, more preferably from 12 to 32 mol %, and even more preferably from 13 to 30 mol %.

[0034] When the content of the structural unit (ii) in the copolymer (B) is 10 mol % or more, further flexibility can be imparted to a film containing the resin composition (X).

[0035] Examples of the α-olefin having 2 to 4 carbon atoms that forms the structural unit (ii) include ethylene, propylene, and 1-butene. These may be used alone, or two or more may be combined as long as the present invention is not impaired. Among these, propylene is particularly preferred as the α-olefin having 2 to 4 carbon atoms, as it provides good dispersibility in the polybutylene terephthalate (A) contained in the resin composition (X).

[0036] The 4-methyl-1-pentene and the α-olefin copolymer having 2 to 4 carbon atoms, which are monomers constituting the 4-methyl-1-pentene / α-olefin copolymer (B), may be monomers derived from fossil fuels, may be monomers derived from biomass, or may be a combination of monomers derived from fossil fuels and monomers derived from biomass.

[0037] In addition to requirement (Ba-a), the 4-methyl-1-pentene / α-olefin copolymer (B) preferably satisfies one or more requirements selected from the following requirements (B-b), (B-c), and (B-d), more preferably satisfies two or more requirements, and even more preferably satisfies three requirements. Furthermore, in addition to requirement (Ba-a), the 4-methyl-1-pentene / α-olefin copolymer (B) preferably satisfies at least one of the following requirements (B-e) and (B-g):

[0038] [Requirement (B-b)] The melting point (Tm) measured by a differential scanning calorimeter (DSC) is not observed or is in a range of less than 160° C. If the copolymer (B) has a melting point, the upper limit thereof is preferably 150° C., more preferably 145° C., and even more preferably 140° C. or lower.

[0039] The melting point value described above varies depending on the stereoregularity of the copolymer (B) and the α-olefin of the structural unit (ii) polymerized together with the structural unit (i). The melting point can be adjusted to a desired composition using an α-olefin polymerization catalyst described below. The measurement method is as described in the Examples described below.

[0040] The release film obtained from resin composition (X) has excellent conformability to the fine steps (uneven shapes) of an FPC and also has excellent wrinkle suppression. It is believed that these functions are further exhibited due to the stress relaxation properties of copolymer (B). Stress relaxation properties can be evaluated, for example, by the loss tangent tanδ, which is the ratio (G″ / G′) of the storage modulus G′ to the loss modulus G″ measured by dynamic viscoelasticity. The storage modulus G′ refers to an elastic component that stores and retains stress energy when stress is applied. The loss modulus G″ refers to a viscous component that converts stress energy into heat and releases it (diffuses it to the outside) when stress is applied. Therefore, from the viewpoint that a material with a higher loss tangent tanδ under a specific temperature environment is more likely to absorb impact and exhibit higher stress relaxation properties, it is preferable that copolymer (B) satisfy the following requirements (B-c) and (B-d).

[0041] [Requirement (B-c)] The maximum value of loss tangent tanδ (hereinafter sometimes referred to as "peak tanδ") determined by dynamic viscoelasticity measurement in a temperature range of -40 to 150°C, in a torsion mode, at a frequency of 1.0 Hz, at a heating rate of 4°C / min, and at a strain setting of 0.5% is preferably in the range of 0.5 to 5.0, more preferably 0.6 to 4.5, and even more preferably 0.7 to 4.0.

[0042] From the viewpoint of exhibiting the effect of easily relaxing stress such as distortion and deformation that occurs during press molding in the FPC manufacturing process, the tan δ peak value of the copolymer (B) alone is preferably 1.0 or more.

[0043] [Requirement (B-d)] In a temperature range of −40 to 150° C., the temperature at which the loss tangent tanδ, determined by dynamic viscoelasticity measurement in a torsion mode at a frequency of 1.0 Hz, a heating rate of 4° C. / min, and a strain setting of 0.5%, reaches a maximum (hereinafter, this may be referred to as the “tanδ peak temperature”) is −20 to 60° C., preferably −10 to 55° C., and more preferably 0 to 50° C.

[0044] When the tan δ peak temperature of copolymer (B) alone is within the above range, the resulting molded product exhibits the effect of easily alleviating stresses such as distortion and deformation that occur during press molding in the FPC manufacturing process, which is preferable. Specific measurement methods are as described in the Examples below. The tan δ peak value and tan δ peak temperature can be adjusted by adjusting the composition ratio of structural units (i) and (ii) in copolymer (B). The tan δ peak value and tan δ peak temperature of copolymer (B) do not change significantly even when copolymer (B) is pelletized, for example, containing a heat stabilizer.

[0045] In addition to requirement (Ba-a), the 4-methyl-1-pentene / α-olefin copolymer (B) preferably further satisfies one or more requirements selected from the following requirements (Ba-e), (Ba-f), and (Ba-g), more preferably satisfies two or more requirements, and even more preferably satisfies three requirements. Furthermore, in addition to requirements (Ba-a), (Ba-e), (Ba-f), and (Ba-g), the copolymer (B) may also satisfy at least one of requirements (Ba-b), (Ba-c), and (Ba-d).

[0046] [Requirement (B-e)] The intrinsic viscosity [η] measured in decalin solvent at 135°C is 0.5 to 5.0 dl / g, preferably 0.6 to 4.0 dl / g, and more preferably 0.8 to 3.0 dl / g. When the intrinsic viscosity [η] of the copolymer (B) is in the above range, the content of low-molecular-weight components is low, which reduces stickiness and facilitates film formation, making this preferable. Specific methods for measuring the intrinsic viscosity [η] are as described in the Examples below.

[0047] [Requirement (B-f)] Density is 820 to 860 kg / m ３ and preferably 825 to 855 kg / m ３ , more preferably 830 to 850 kg / m ３The density of the copolymer (B) is preferably in the above range, since it can impart flexibility to a film containing the resin composition (X). The method for measuring the density is as described in the Examples below.

[0048] [Requirement (B-g)] The molecular weight distribution (Mw / Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC), is 1.0 to 4.0, preferably 1.2 to 3.5, and more preferably 1.5 to 3.0. When the molecular weight distribution (Mw / Mn) is 4.0 or less, the influence of low molecular weight polymers and low stereoregularity polymers resulting from the composition distribution is reduced, and films containing the resin composition (X) have better releasability. Furthermore, the weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) is preferably 500 to 10,000,000, more preferably 1,000 to 5,000,000, and even more preferably 5,000 to 2,500,000, in terms of polystyrene. When the weight average molecular weight (Mw) is within the above range, the film is likely to achieve appropriate rigidity. The weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) can be determined by the measurement methods described in the examples below.

[0049] The content of copolymer (B) is 5 to 50 parts by mass, preferably 6 to 48 parts by mass, more preferably 7 to 44 parts by mass, and even more preferably 8 to 42 parts by mass (where the total of polybutylene terephthalate (A) and copolymer (B) is 100 parts by mass). When the content of copolymer (B) is within the above range, the film obtained from resin composition (X) has excellent conformability to the fine steps (uneven shape) of the FPC and also has excellent heat resistance. The copolymer (B) may be used alone or in combination of two or more types.

[0050] <Method for Producing Copolymer (B)> The method for producing copolymer (B) is not particularly limited, and the copolymer (B) can be produced, for example, by polymerizing 4-methyl-1-pentene and the above-mentioned α-olefin having 2 to 4 carbon atoms in the presence of an appropriate polymerization catalyst such as a magnesium-supported titanium catalyst or a metallocene catalyst.

[0051] Suitable polymerization catalysts that can be used here include conventionally known catalysts, such as magnesium-supported titanium catalysts, and metallocene catalysts described in International Publication Nos. 2001 / 53369, 2001 / 27124, JP-A-3-193796, JP-A-2-41303, JP-A-2011 / 055803, JP-A-2014 / 050817, etc. Polymerization can be carried out by a method appropriately selected from liquid phase polymerization methods including solution polymerization and suspension polymerization, and gas phase polymerization methods.

[0052] In the liquid phase polymerization method, an inert hydrocarbon solvent can be used as a solvent constituting the liquid phase. Examples of the inert hydrocarbon include aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane, octane, decane, dodecane, and kerosene, alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane, aromatic hydrocarbons such as benzene, toluene, and xylene, and halogenated hydrocarbons such as ethylene chloride, chlorobenzene, dichloromethane, trichloromethane, and tetrachloromethane, and mixtures thereof.

[0053] Furthermore, in the liquid phase polymerization method, bulk polymerization may be carried out using the monomer corresponding to the structural unit (i) derived from the aforementioned 4-methyl-1-pentene (i.e., 4-methyl-1-pentene) and the monomer corresponding to the structural unit (ii) derived from the aforementioned α-olefin having 2 to 4 carbon atoms (i.e., the aforementioned α-olefin having 2 to 4 carbon atoms) themselves as a solvent.

[0054] Furthermore, by carrying out the copolymerization of the above-mentioned 4-methyl-1-pentene with the above-mentioned α-olefin having 2 to 4 carbon atoms in a stepwise manner, it is also possible to appropriately adjust the composition distribution of the 4-methyl-1-pentene structural units (i) and the α-olefin structural units (ii) constituting the copolymer (B) to the copolymer (B).

[0055] The polymerization temperature when polymerizing the copolymer (B) is preferably −50 to 200° C., more preferably 0 to 100° C., and even more preferably 20 to 100° C. The polymerization pressure when polymerizing the copolymer (B) is preferably normal pressure to 10 MPa gauge pressure, and more preferably normal pressure to 5 MPa gauge pressure.

[0056] During polymerization of the copolymer (B), hydrogen may be added for the purpose of controlling the molecular weight of the resulting polymer and the polymerization activity. The amount of hydrogen to be added is suitably about 0.001 to 100 NL per 1 kg of the total amount of the 4-methyl-1-pentene and the α-olefin having 2 to 4 carbon atoms.

[0057] The resin composition (X) may further contain at least one elastomer selected from the group consisting of a polyester-based elastomer (D) and a styrene-based elastomer (E).

[0058] <<Polyester-Based Elastomer (D)>> The polyester-based elastomer (D) is preferably a block copolymer whose hard segment (hard) has a chemical structure composed of a polyester component. In such a block copolymer, the hard segment is generally an aromatic crystalline polyester, and the soft segment (flexible) is a polymer having a low glass transition temperature (Tg). The polyester-based elastomer (D) can be appropriately designed to a desired polyester-based elastomer by changing the type of polyester in the hard segment and / or the type of polymer in the soft segment.

[0059] The polyester elastomer (D) may be synthesized, or a commercially available product may be used. Examples of commercially available products include Hytrel (registered trademark) manufactured by Toray Celanese Co., Ltd. and Belprene P Type (registered trademark) manufactured by Toyobo MC Co., Ltd., which are block copolymers using polybutylene terephthalate as the polyester component of the hard segment and polytetramethylene ether glycol as the polyether component of the soft segment (i.e., polyester-polyether type block copolymers). Such polyester-polyether type block copolymers have excellent moldability and low-temperature flexibility by using polybutylene terephthalate, which has excellent heat resistance, as the hard segment and polytetramethylene ether glycol, which has a low glass transition temperature (Tg), as the soft segment.

[0060] Furthermore, the polyester elastomer (D) is a block copolymer that uses polybutylene terephthalate as the polyester component of the hard segment and polylactone, an aliphatic polyester, as the polyester component of the soft segment, and is exemplified by the Belprene S type manufactured by Toyobo MC Co., Ltd. Such copolymers have better heat aging resistance and weather resistance than the aforementioned polyester-polyether type block copolymers. The polyester elastomer (D) may be used alone or in combination of two or more types.

[0061] Among these, as the polyester-based elastomer (D), a polyester-polyether type block copolymer is preferred from the viewpoint of superior compatibility with the polybutylene terephthalate (A) and copolymer (B).Furthermore, when the resin composition (X) contains a polyester-polyether type block copolymer, the crystallization rate of the polybutylene terephthalate (A) can be delayed and the degree of crystallinity can be reduced, which is preferable because the smoothness of the film surface can be improved.

[0062] The melting point (Tm) of the polyester elastomer (D) is preferably 140 to 250° C., more preferably 150 to 240° C., and even more preferably 160 to 230° C. If the melting point of the polyester elastomer (D) is within the above range, it is preferable because a film having good compatibility with the polybutylene terephthalate (A) and heat resistance can be obtained.

[0063] The content of the polyester elastomer (D) and the content of the at least one elastomer selected from the group consisting of styrene elastomers (E) described below, relative to 100 parts by mass of the resin composition (X), is preferably 0 to 30 parts by mass, more preferably 0 to 25 parts by mass, even more preferably 5 to 20 parts by mass, and most preferably 5 to 15 parts by mass. When the content of the polyester elastomer (D) and / or the styrene elastomer (E) is within the above range, the smoothness of the obtained film surface is improved, and the neck-in phenomenon in the resin film during T-die extrusion molding is more effectively suppressed.

[0064] <Styrene-based elastomer (E)> The styrene-based elastomer (E) is not particularly limited, and examples thereof include styrene-butadiene-styrene block copolymer (SBS), which is a copolymer of polystyrene as a hard segment (hard) and butadiene as a soft segment (flexible), styrene-butadiene-butylene-styrene block copolymer (SBBS), hydrogenated styrene-butadiene-styrene block copolymer (HBSR), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-isoprene-styrene block copolymer (SIS), styrene-isobutylene-styrene block copolymer (SIBS), styrene-isobutylene block copolymer (SIB), etc. The styrene-based elastomer (E) may be used alone or in combination of two or more.

[0065] The styrene elastomer (E) may be synthesized or a commercially available product may be used. Examples of commercially available styrene elastomers (E) include styrene-butadiene-styrene block copolymers (SBS) in which butadiene-derived components of a styrene-butadiene copolymer are hydrogenated and a styrene moiety is copolymerized in a soft segment, such as S.O.M. manufactured by Asahi Kasei Corporation. Examples of styrene-butadiene-butylene-styrene block copolymers (SBBS) include the Tuftec P series (registered trademark) manufactured by Asahi Kasei Corporation; styrene-ethylene-butylene-styrene block copolymers (SEBS) include the Tuftec H series (registered trademark) manufactured by Asahi Kasei Corporation; and Kraton G series (registered trademark) manufactured by Kraton Polymer Japan Co., Ltd.; and styrene-isobutylene-styrene block copolymers (SIBS) and styrene-isobutylene block copolymers (SIB) include SIBSTAR (registered trademark) manufactured by Kaneka Corporation.

[0066] The styrene content in the styrene-based elastomer (E) is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 8% by mass or more and 50% by mass or less. If the styrene content is less than 2% by mass, the film obtained from the resin composition (X) tends to be flexible and the adhesive strength tends to be improved. If the styrene content exceeds 50% by mass, the film obtained tends to be hard and the adhesive strength tends to be reduced. On the other hand, if the styrene content is within the above range, a film with appropriate adhesiveness is easily obtained, and a molded article obtained from the resin composition (X) is excellent in conformability and wrinkle suppression.

[0067] The styrene-based elastomer (E) may be an unmodified styrene-based elastomer, or may be a styrene-based elastomer modified with at least one functional group selected from the group consisting of acid anhydride groups, carboxy groups, amino groups, imino groups, alkoxy groups, silanol groups, silyl ether groups, hydroxy groups, and epoxy groups. From the viewpoint of achieving better compatibility between the highly polar polybutylene terephthalate (A) and the copolymer (B), the styrene-based elastomer (E) is preferably a styrene-based elastomer modified with maleic anhydride (maleic anhydride-modified styrene-based elastomer). Commercially available maleic anhydride-modified styrene-based elastomers may be used, including, for example, Tuftec M Series (registered trademark) manufactured by Asahi Kasei Corporation and Kraton FG Polymer (registered trademark) manufactured by Kraton Polymer Japan Co., Ltd.

[0068] <Resin Composition (X)> The resin composition (X) contains 50 to 95 parts by mass, preferably 52 to 94 parts by mass, more preferably 56 to 93 parts by mass, and even more preferably 58 to 92 parts by mass of polybutylene terephthalate (A), and 5 to 50 parts by mass, preferably 6 to 48 parts by mass, more preferably 7 to 44 parts by mass, and even more preferably 8 to 42 parts by mass of 4-methyl-1-pentene / α-olefin copolymer (B) satisfying the above-mentioned requirement (Ba) (where the total of the polybutylene terephthalate (A) and the copolymer (B) is 100 parts by mass).

[0069] [Method for producing resin composition (X)] The resin composition (X) can be obtained by mixing polybutylene terephthalate (A) and copolymer (B) in the above-mentioned specific ratio. The mixing method is not particularly limited, and various known methods can be used, such as dry blending the above components using a Henschel mixer, tumbler blender, V-blender, etc., dry blending the components and then melt-kneading them using a single-screw extruder, twin-screw extruder, Banbury mixer, etc., and stirring and mixing in the presence of a solvent.

[0070] The resin composition (X) may contain components other than the polybutylene terephthalate (A), the copolymer (B), the polyester elastomer (D), and the styrene elastomer (E) (hereinafter referred to as "other components") as necessary to the extent that the effects of the present invention are not impaired. Examples of other components include various additives such as antioxidants, antistatic agents, surfactants, fibers, inorganic or organic fillers, ultraviolet absorbers, crystal nucleating agents, pigments, hydrochloric acid absorbers, crosslinking agents, crosslinking aids, softeners, and flame retardants, as well as resins other than the polybutylene terephthalate (A), the copolymer (B), the polyester elastomer (D), and the styrene elastomer (E).

[0071] As the antioxidant, known antioxidants can be used. Specific examples include hindered phenol compounds, sulfur-based antioxidants, lactone-based antioxidants, organic phosphite compounds, organic phosphonite compounds, and combinations of several of these. Examples include phenol-based antioxidants (2,6-di-t-butyl-4-methylphenol, etc.), polycyclic phenol-based antioxidants (2,2'-methylenebis(4-methyl-6-t-butylphenol), etc.), phosphorus-based antioxidants (tetrakis(2,4-di-t-butylphenyl)-4,4-biphenylenediphosphonate, etc.), and amine-based antioxidants (N,N-diisopropyl-p-phenylenediamine, etc.).

[0072] The antistatic agent is not particularly limited, and examples thereof include surfactants, fatty acid esters, polymeric antistatic agents, etc. Examples of fatty acid esters include esters of stearic acid and oleic acid, and examples of polymeric antistatic agents include polyether ester amides.

[0073] The surfactant is not particularly limited, and examples thereof include nonionic, anionic, cationic or amphoteric surfactants.The nonionic surfactants include polyethylene glycol-type nonionic surfactants such as higher alcohol ethylene oxide adducts, fatty acid ethylene oxide adducts, higher alkylamine ethylene oxide adducts, and polypropylene glycol ethylene oxide adducts, polyethylene oxide, glycerin fatty acid esters, pentaerythritol fatty acid esters, sorbit or sorbitan fatty acid esters, polyhydric alcohol alkyl ethers, and alkanolamine fatty acid amides.The anionic surfactants include sulfate ester salts such as alkali metal salts of higher fatty acids, sulfonates such as alkylbenzenesulfonates, alkylsulfonates, and paraffin sulfonates, and phosphate ester salts such as higher alcohol phosphate ester salts.The cationic surfactants include quaternary ammonium salts such as alkyltrimethylammonium salts. Examples of amphoteric surfactants include amino acid type amphoteric surfactants such as higher alkylaminopropionates, and betaine type amphoteric surfactants such as higher alkyldimethylbetaine and higher alkyldihydroxyethylbetaine.

[0074] The content of the other components is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 2 parts by mass or less, relative to 100 parts by mass in total of the polybutylene terephthalate resin (A), the copolymer (B), the polyester-based elastomer (D), and the styrene-based elastomer (E) in the resin composition (X).

[0075] Furthermore, the content of resins other than the polybutylene terephthalate resin (A), the copolymer (B), the polyester-based elastomer (D), and the styrene-based elastomer (E) is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 5 parts by mass, particularly preferably 1 part by mass or less, and most preferably substantially none, per 100 parts by mass of the total of the polybutylene terephthalate resin (A), the copolymer (B), the polyester-based elastomer (D), and the styrene-based elastomer (E).

[0076] <Molded Article> The molded article according to the present invention contains the resin composition (X). The molded article can be produced into a desired shape by molding the resin composition (X) using a conventionally known molding method, such as heat press molding, compression molding, injection molding, and extrusion molding. In the case of injection molding, the molded article can be produced using a desired mold.

[0077] The shape of the molded product is not particularly limited, and may be, for example, any of a sheet shape, a film shape, a plate shape, a cylindrical shape, a prismatic shape, etc. Among these, a film shape is preferred as the shape of the molded product from the viewpoint of excellent releasability, conformability, and suppression of wrinkle formation.

[0078] <Film> The film according to the present invention contains the resin composition (X) and preferably consists of the resin composition (X). The film may be a single-layer film, a multilayer film in which a layer containing the resin composition (X) is laminated with another layer, or a multilayer film in which multiple layers containing the resin composition (X) are laminated. The use of the film is not particularly limited, and examples thereof include protective films, decorative films, shrink films, heat-sealing films, and release films. Among these, the film is preferably used as a release film from the viewpoint of excellent releasability, conformability, and wrinkle suppression.

[0079] The release film is not particularly limited, and examples thereof include release films for flexible printed circuit boards (FPCs), release films for ACM substrates, release films for rigid substrates, release films for rigid flexible wiring boards, release films for advanced composite materials, release films for the process of producing fiber reinforced composites, release films for curing carbon fiber composites, release films for molding carbon fiber composites, release films for curing glass fiber composites, release films for molding glass fiber composites, release films for curing aramid fiber composites, release films for molding aramid fiber composites, and release films for curing nanocomposite materials. Examples of the release film include a release film for hardening a filler material, a release film for sealing a semiconductor, a release film for a polarizing plate, a release film for a diffusion sheet, a release film for a prism sheet, a release film for a reflection sheet, a cushion film for a release film, a release film for a fuel cell, a release film for various rubber sheets, a release film for hardening a urethane, a release film for hardening an epoxy, a release film for a silicone resin, a release film for a mold for an LED encapsulant, a release film for an acrylic pressure sensitive adhesive, a release film for a protect film, and a release film for synthetic leather.

[0080] The release film can also be used for release papers such as release paper for synthetic leather, release paper for advanced composite materials, release paper for curing carbon fiber composite materials, release paper for curing glass fiber composite materials, release paper for curing aramid fiber composite materials, release paper for curing nanocomposite materials, and release paper for curing filler materials, as well as release papers such as heat-resistant and water-resistant photographic paper.

[0081] <Film Manufacturing Method> The film manufacturing method is not particularly limited, and known methods such as extrusion cast molding and extrusion lamination molding can be used. An example of a film manufacturing method is described below, but the film manufacturing method of the present invention is not limited to this. First, using an extruder connected to a T-die, the materials to be used in the resin composition (X) are introduced. Then, the cylinder temperature is set to 240 to 260°C and the T-die temperature is set to 240 to 250°C to melt the resin. The molding machine may be a single-screw extruder or a twin-screw extruder. The molten resin is extruded through the T-die and cooled and solidified at a cast roll temperature of 50 to 80°C, thereby obtaining a single-layer release film.

[0082] The thickness of the film is not particularly limited and can be determined appropriately as desired. The thickness of the release film is usually 10 to 300 μm, preferably 15 to 250 μm, and more preferably 20 to 200 μm. When the film is 10 μm or thicker, it has appropriate rigidity, making it easy to handle and less likely to tear when peeled off. Furthermore, when the thickness of the release film is 300 μm or less, it is advantageous for the film to be lightweight and for its ability to conform to steps (e.g., uneven shapes) on the FPC.

[0083] <Film Properties> The critical surface tension of the film at 23°C is preferably 20 to 30 mN / m. The critical surface tension value indicates the releasability of the film surface. The smaller the critical surface tension value, the better the releasability.

[0084] The critical surface tension of the film is more preferably 21 to 29 mN / m, and even more preferably 22 to 28 mN / m. When the critical surface tension of the film is in the above range, the film has excellent releasability. When the film is used as a release film for flexible printed circuit boards (FPCs), this is preferable because it suppresses the occurrence of problems such as the film adhering to the FPC and breaking, or the electrical circuit of the FPC peeling off and breaking, when the film is peeled off after press molding in the FPC manufacturing process.

[0085] An example of a method for measuring the critical surface tension is a calculation method using a Zisman plot. The calculation method using a Zisman plot involves measuring the contact angle of a solid with respect to various liquids having different surface tensions, and plotting the surface tension of each liquid on the horizontal axis and the measured contact angle (cos θ) of the solid on the vertical axis to obtain a direct relationship. The resulting line is extrapolated up to cos θ = 1.0, which is considered to be a completely wet state, and the critical surface tension (mN / m) of the solid can be determined from the intersection with the horizontal axis. Details of the measurement conditions for the critical surface tension, etc., are as described in the Examples below.

[0086] The film preferably has a solid viscoelastic storage modulus E' at 180°C measured under conditions of a tensile mode, a frequency of 1.0 Hz, a heating rate of 3°C / min, and a strain of 0.1%, in the range of 10 to 90 MPa, more preferably 12 to 88 MPa, even more preferably 15 to 85 MPa, and particularly preferably 20 to 80 MPa. Specific methods for measuring the solid viscoelastic storage modulus E' are as described in the Examples below.

[0087] When the above film is used as a release film for flexible printed circuit boards (FPCs), since the storage modulus E' of the solid viscoelasticity at 180°C of the film is within the above-mentioned range, stresses such as distortion and deformation that occur during press molding in the FPC manufacturing process are alleviated, resulting in excellent conformability to steps (e.g., uneven shapes) in the FPC, preventing the adhesive from flowing into the terminal portions, reducing the occurrence of wrinkles, and excellent releasability.

[0088] When the storage modulus E' of the solid viscoelasticity at 180°C is 10 MPa or more, the film has excellent heat resistance at high temperatures and can be suitably used as a release film for the printed circuit board manufacturing process. When the storage modulus E' of the solid viscoelasticity at 180°C is 90 MPa or less, the film has an appropriate rigidity, and therefore has excellent conformability to the fine steps (uneven shapes) of the FPC, and the outflow of the adhesive to the terminal portion is suppressed.

[0089] The maximum value of the loss tangent tanδ of the solid viscoelasticity of the film at 20 to 35°C (hereinafter sometimes referred to as "peak tanδ") measured under conditions of a tensile mode, a frequency of 1.0 Hz, a heating rate of 3°C / min, and a strain of 0.1% is preferably in the range of 0.02 to 0.30, more preferably in the range of 0.022 to 0.29, and even more preferably in the range of 0.024 to 0.28. The method for measuring the peak tanδ is as described in the Examples below.

[0090] When the peak value of the loss tangent tanδ of the solid viscoelasticity at 20 to 35°C, measured under conditions of a tensile mode, a frequency of 1.0 Hz, a heating rate of 3°C / min, and a strain of 0.1%, is within the above-mentioned range, the film is particularly preferred when used as a release film for flexible printed circuit boards (FPCs), because it has excellent conformability to the steps (uneven shape) of the FPC from the initial stage when pressure begins to be applied in press molding in the FPC manufacturing process, and the adhesive applied to the coverlay is less likely to ooze out due to heating and pressure even if the FPC has unevenness, making it easier to ensure opening holes that expose the copper foil as desired.

[0091] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. The methods for measuring the physical properties of resins, the resins used, the methods for preparing test pieces, and the evaluation methods in the following examples and comparative examples are as follows.

[0092] <<Methods for Measuring Physical Properties of Polymers>> <Content of Structural Units> The amount of structural units derived from 4-methyl-1-pentene and the amount of structural units derived from α-olefins contained in copolymer (B) were measured using the following apparatus and conditions. １３ The amount of structural units derived from α-olefins in this measurement result does not include the amount of structural units derived from 4-methyl-1-pentene. A nuclear magnetic resonance spectrometer (manufactured by JEOL Ltd., model number: ECP500) was used, and the measurement was performed using a mixed solvent of o-dichlorobenzene / deuterated benzene (80 / 20% by volume), a sample concentration of 55 mg / 0.6 mL, a measurement temperature of 120°C, and observation nuclei of １３C (125 MHz), sequence was single pulse proton decoupling, pulse width was 4.7 μsec (45° pulse), repetition time was 5.5 sec, number of accumulations was 10,000 or more, and 27.50 ppm was used as the reference value of the chemical shift. １３ The composition of the copolymer (B) was quantified by C-NMR spectrum.

[0093] <Intrinsic viscosity (η)> The intrinsic viscosity of the copolymer (B) was determined using an Ubbelohde viscometer in a decalin solvent at 135°C. Approximately 20 mg of sample was collected for each copolymer (B). Here, the sample may be in the form of a polymer powder, pellet, or resin block. The sample was dissolved in 15 mL of decalin, and the specific viscosity ηsp was measured in an oil bath heated to 135°C. After diluting the decalin solution with 5 mL of decalin solvent, the specific viscosity ηsp was measured in the same manner. This dilution procedure was repeated two more times, and the value of ηsp / C when the concentration (C) was extrapolated to zero was calculated as the intrinsic viscosity (η) (see the formula below). [η] = lim(ηsp / C) (C → 0)

[0094] <Weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn)> The molecular weight of the copolymer (B) was measured by gel permeation chromatography (GPC). Specifically, a Waters ALC / GPC150-Cplus liquid chromatograph (integrated with a differential refractometer detector) was used, two Tosoh GMH6-HT columns and two Tosoh GMH6-HTL columns connected in series were used as separation columns, o-dichlorobenzene was used as the mobile phase medium, and 0.025% by mass of dibutylhydroxytoluene (Takeda Pharmaceutical Co., Ltd.) was used as the antioxidant. The mobile phase medium was moved at 1.0 mL / min, the sample concentration was 15 mg / 10 mL, the sample injection amount was 500 μL, and a differential refractometer was used as the detector. Standard polystyrenes with weight-average molecular weights (Mw) of 1,000 or more and 4,000,000 or less, manufactured by Tosoh Corporation, were used. The obtained chromatograms were analyzed by creating a calibration curve using standard polystyrene samples by a known method, to calculate the weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn). The measurement time per sample was 60 minutes.

[0095] <Melt Flow Rate (MFR)> The MFR of the copolymer (B) was measured in accordance with ASTM D1238 at a temperature of 230°C and a load of 2.16 kgf.

[0096] <Melting Point (Tm)> The melting point (Tm) of the copolymer (B) was measured in accordance with JIS K7121 using a differential scanning calorimeter (manufactured by Hitachi High-Tech Corporation, model number: DSC200) by placing about 5 mg of a sample in a measurement aluminum pan and heating it to 200°C at a heating rate of 10°C / min. The temperature of the highest melting peak among the measured melting peaks was taken as the melting point. When no melting peak appeared, it was evaluated that no melting point was observed.

[0097] <Density> The density of the copolymer (B) was measured using a density gradient tube in accordance with JIS K7112.

[0098] <Polybutylene terephthalate (A-1)> Polybutylene terephthalate (A-1) was manufactured by Mitsubishi Chemical Corporation, product name: Novaduran 5010R (MVR = 21 cm３ For film molding, pellets of polybutylene terephthalate (A-1) were dried in a hot air dryer at 120°C for 5 hours.

[0099] <Polybutylene terephthalate (A-2)> Polybutylene terephthalate (A-2) was manufactured by Mitsubishi Chemical Corporation, product name: Novaduran 5010R5 L2 (MVR = 35 cm ３ For film molding, pellets of polybutylene terephthalate (A-2) were dried in a hot air dryer at 120°C for 5 hours.

[0100] <Synthesis of Copolymer (B)> As copolymer (B), two types of copolymer (B-1) and copolymer (B-2) differing in the content ratio of the structural unit (i) derived from 4-methyl-1-pentene and the structural unit (ii) derived from an α-olefin having 2 to 4 carbon atoms were synthesized according to the following synthesis method.

[0101] Synthesis Example 1 Synthesis of Copolymer (B-1) A 1.5 L capacity SUS autoclave equipped with a stirring blade and thoroughly purged with nitrogen was charged with 300 mL of n-hexane (dried over activated alumina under a dry nitrogen atmosphere) and 450 mL of 4-methyl-1-pentene at 23° C. 0.75 mL of a 1.0 mmol / mL toluene solution of triisobutylaluminum (TIBAL) was charged to the autoclave and stirred.

[0102] Next, the autoclave was heated to an internal temperature of 60°C and pressurized with propylene to a total pressure (gauge pressure) of 0.40 MPa. Subsequently, 0.34 mL of a toluene solution containing 1 mmol of methylaluminoxane (calculated as aluminum) and 0.01 mmol of diphenylmethylene(1-ethyl-3-t-butyl-cyclopentadienyl)(2,7-di-t-butyl-fluorenyl)zirconium dichloride, which had been prepared in advance, was injected into the autoclave with nitrogen to initiate the polymerization reaction. During the polymerization reaction, the internal temperature of the autoclave was adjusted to 60°C. Sixty minutes after the start of polymerization, 5 mL of methanol was injected into the autoclave with nitrogen to terminate the polymerization reaction, and the autoclave was then depressurized to atmospheric pressure. After depressurization, the reaction solution was stirred while acetone was added.

[0103] The obtained powdery copolymer containing the solvent was dried at 100°C under reduced pressure for 12 hours. The mass of the product, copolymer (B-1), was 36.9 g. In copolymer (B-1), the amount of structural units derived from 4-methyl-1-pentene was 72.4 mol%, and the content of structural units (i) derived from propylene was 27.6 mol%. When DSC measurement was performed, no melting point was observed. The measurement results of each physical property of the obtained copolymer (B-1) are shown in Table 1.

[0104] <<Preparation of Pellets>> Next, 100 parts by mass of the copolymer (B-1) was blended with 1000 ppm of tetrakis[3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionic acid]pentaerythritol as a heat stabilizer and 1000 ppm of tris(2,4-di-t-butylphenyl)phosphate as a secondary antioxidant, and the blend was extruded using a twin-screw extruder (manufactured by The Japan Steel Works, Ltd., model number: TEX25αIII, screw diameter 25 mm, L / D = 52) at a cylinder set temperature of 200°C, an extrusion rate of 5 kg / hour, and a screw rotation speed of 100 rpm to produce strands. The strands were then immersed in a water tank and introduced into a pelletizer (manufactured by Katsumik Co., Ltd., model number: KM-100) for granulation, thereby preparing pellets containing copolymer (B-1).

[0105] Synthesis Example 2 Synthesis of Copolymer (B-2) A 1.5 L capacity SUS autoclave equipped with a stirring blade and thoroughly purged with nitrogen was charged with 300 mL of n-hexane (dried over activated alumina under a dry nitrogen atmosphere) and 450 mL of 4-methyl-1-pentene at 23° C. 0.75 mL of a 1.0 mmol / mL toluene solution of triisobutylaluminum (TIBAL) was charged to the autoclave and stirred.

[0106] Next, the autoclave was heated to an internal temperature of 60°C and pressurized with propylene to a total pressure (gauge pressure) of 0.19 MPa. Subsequently, 0.34 mL of a toluene solution containing 1 mmol of methylaluminoxane (calculated as aluminum) and 0.01 mmol of diphenylmethylene(1-ethyl-3-t-butyl-cyclopentadienyl)(2,7-di-t-butyl-fluorenyl)zirconium dichloride, which had been prepared in advance, was injected into the autoclave with nitrogen to initiate the polymerization reaction. During the polymerization reaction, the internal temperature of the autoclave was adjusted to 60°C. 60 minutes after the start of polymerization, 5 mL of methanol was injected into the autoclave with nitrogen to terminate the polymerization reaction, and the autoclave was then depressurized to atmospheric pressure. After depressurization, the reaction solution was stirred while acetone was added.

[0107] The obtained powdery polymer containing the solvent was dried at 130°C under reduced pressure for 12 hours. The mass of the product, copolymer (B-2), was 44.0 g. In copolymer (B-2), the content of structural units (i) derived from 4-methyl-1-pentene was 84.1 mol%, and the content of structural units (ii) derived from propylene was 15.9 mol%. When DSC measurement was performed, the melting point was 130°C. The measurement results of each physical property of the obtained copolymer (B-2) are shown in Table 1.

[0108] <<Preparation of Pellets>> Next, 100 parts by mass of the copolymer (B-2) was blended with 1000 ppm of tetrakis[3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionic acid]pentaerythritol as a heat stabilizer and 1000 ppm of tris(2,4-di-t-butylphenyl)phosphate as a secondary antioxidant, and the blend was extruded using a twin-screw extruder (manufactured by The Japan Steel Works, Ltd., model number: TEX25αIII, screw diameter 25 mm, L / D=52) at a cylinder set temperature of 200°C, an extrusion rate of 5 kg / hour, and a screw rotation speed of 100 rpm to produce strands. The strands were then immersed in a water tank and introduced into a pelletizer (manufactured by Katsumik Co., Ltd., model number: KM-100) for granulation to prepare pellets containing copolymer (B-2).

[0109] <Measurement of dynamic viscoelasticity> A predetermined amount of each of the copolymers (B-1) and (B-2) obtained by the above-mentioned method was filled into an SUS mold. The heating plate was set to 200°C, and using a hydraulic hot press (manufactured by Shinto Metal Industries Co., Ltd., model number: NSF-50), the mixture was preheated for 7 minutes and pressed at a gauge pressure of 10 MPa for 2 minutes, then transferred to a cooling plate set to 20°C, compressed at a gauge pressure of 10 MPa, and cooled for 2 minutes to prepare a press sheet for measurement with a thickness of 2 mm.

[0110] Next, the temperature dispersion of dynamic viscoelasticity was observed from −40 to 150°C using a rheometer (Anton Paar, model MCR301) under the conditions of torsion mode, frequency 1.0 Hz, heating rate 4°C / min, and strain 0.5% for the 2 mm-thick measurement press sheet obtained by the above method, and the tan δ peak value and tan δ peak temperature were measured. The results are shown in Table 1.

[0111]

[0112] Example 1 A resin composition (X) was prepared by mixing (dry blending) 90 parts by mass of polybutylene terephthalate (A-1) and 10 parts by mass of the pellets containing copolymer (B-1) prepared above using a tumbler blender.

[0113] [Preparation of Release Film] Next, the resin composition (X-1) prepared above was placed in the raw material hopper of a single-screw extruder equipped with a T-die (screw diameter 20 mm, L / D = 24, T-die width 300 mm, lip opening 2 mm). The cylinder temperature was set to 240-250°C, and the T-die temperature was set to 250°C. While the molten resin was extruded from the T-die, the casting roll temperature was set to 60°C and the take-up speed was set to 0.8 m / min. A release film was produced to a monolayer film thickness of 50 μm, yielding a release film. During film production, the film surface that first came into direct contact with the casting roll was designated the release surface, and the other film surface was designated the back surface. Film formability, release film physical properties, and press molding evaluation were performed as described below. The results are shown in Table 2.

[0114] [Film Formability] The same molding machine as in the above-mentioned "Production of Release Film", a single-screw extruder equipped with a T-die (width 300 mm), was used, and the same cylinder temperature and T-die temperature were set, and the screw rotation speed was adjusted so that the extrusion rate was 5 kg / hour. The molten resin extruded from the T-die was allowed to flow vertically as it was, and the film width (width of the resin film) was measured at a position 50 mm below the lip position of the T-die. The effectiveness of the film width was calculated using the following formula. The higher the effectiveness of the film width, the more the neck-in phenomenon can be suppressed. Effectiveness of film width (%) = {1 - {(T-die width) - (measured film width)} / (T-die width)} × 100

[0115] [Surface roughness] The release surface of the release film produced by the above method was measured for arithmetic mean roughness (Ra) in each of the MD direction (machine direction) and TD direction (direction perpendicular to the resin flow direction, transverse direction) in accordance with JIS B0601 under the conditions of a stylus of 2 μm, a measurement length of 4.0 mm, a cutoff wavelength of 0.8 mm, and a measurement speed of 0.15 mm / sec. The results are shown in Table 2.

[0116] [Critical Surface Tension] To evaluate the critical surface tension of the release surface of the release film prepared by the above method, a mixture liquid for wetting tension testing of ethylene glycol monoethyl ether / formamide mixture liquid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), in which the surface tension of the liquid was adjusted to 31 mN / m, 34 mN / m, 37 mN / m, and 40 mN / m, respectively, was dropped onto the surface of the film in an atmosphere of 23 ° C. and 50% relative humidity. Then, the contact angle was measured using an image processing solid-liquid interface analysis system (manufactured by Kyowa Interface Science Co., Ltd., model number: DropMaster 500). Using the Zisman plot method, the surface tension value of each mixture liquid was plotted on the horizontal axis and the measured value of the contact angle (the angle was converted to radian units and expressed as cos θ) on the vertical axis, and a linear linear function was obtained according to the least squares method. The graph of this linear function was extrapolated up to cos θ = 1.0, which is considered to be a completely wet state, and the surface tension at which cos θ = 1.0 on the graph (i.e., the value on the horizontal axis at the point where cos θ = 1.0 on the graph) was determined as the critical surface tension (mN / m). The results are shown in Table 2.

[0117] [Storage Modulus E' at 180°C] A strip cut from the release film produced by the method described above in the MD direction was used as a test piece, and the storage modulus E' of the solid viscoelasticity at 180°C was measured by temperature dispersion from -50 to 200°C under the conditions of a tension mode, a frequency of 1.0 Hz, a heating rate of 3°C / min, and a strain of 0.1% using a rheometer (manufactured by TA Instruments, model number: RSA-G2). The results are shown in Table 2.

[0118] [Peak Value of Loss Tangent tanδ at 20 to 35°C] A strip cut out from the MD direction of the release film produced by the above-mentioned method was used as a test piece, and the tanδ peak temperature and tanδ peak value of the loss tangent tanδ (expressed as the ratio (E" / E') of the storage modulus E' to the loss modulus E") at 20 to 35°C were determined in the same manner as the solid viscoelasticity observed by the above-mentioned method.

[0119] [Press-molding evaluation of release film] A flexible copper clad laminate (FCCL) was prepared, and the release film was evaluated for releasability, conformability, and wrinkle resistance using a quick press molding device.

[0120] [Release] A flexible copper-clad laminate (width 100 mm x length 200 mm, conductor width L = 100 μm / conductor gap S = 100 μm, polyimide thickness 25 μm, copper foil thickness 35 μm) and a coverlay film (width 100 mm x length 200 mm, polyimide thickness 25 μm, epoxy adhesive layer thickness 35 μm) with a Φ1.0 mm opening were prepared, and the copper foil surface of the flexible copper-clad laminate and the epoxy adhesive layer of the coverlay film were laminated so that they were in contact. Next, the release surface of the release film was laminated so that it was in contact with the coverlay film, and the laminate was heated and pressurized under conditions of a temperature of 180 ° C., a pressure of 3.0 MPa, vacuuming for 5 seconds, and pressure for 2 minutes to produce a laminate. After removing the laminate from the press, a small gap was left at the end of the release film so that the end of the laminate would be the starting point for peeling, and then it was placed on a surface plate. The time required for the release film to be completely peeled off from the laminate was measured, and the releasability was evaluated according to the following evaluation criteria. Evaluation criteria A indicates excellent releasability. -Evaluation criteria- A: Less than 60 seconds were required from the start of peeling to the completion of peeling. B: 60 seconds or more but less than 90 seconds were required from the start of peeling to the completion of peeling. C: 90 seconds or more were required from the start of peeling to the completion of peeling. Alternatively, the release film was not peeled off.

[0121] [Followability] A flexible copper-clad laminate (width 100 mm x length 200 mm, conductor width L = 100 μm / conductor gap S = 100 μm, polyimide thickness 25 μm, copper foil thickness 35 μm) and a coverlay film (width 100 mm x length 200 mm, polyimide thickness 25 μm, epoxy adhesive layer thickness 35 μm) with a Φ1.0 mm opening were prepared, and the copper foil surface of the flexible copper-clad laminate was laminated so that it was in contact with the epoxy adhesive layer side of the coverlay film. Next, the release surface of the release film was laminated so that it was in contact with the coverlay film, and the laminate was heated and pressurized under conditions of a temperature of 180 ° C., a pressure of 3.0 MPa, vacuuming for 5 seconds, and pressure for 2 minutes to produce a laminate. Then, the release film was peeled off, and the epoxy adhesive that had flowed onto the upper surface (copper foil surface) of the flexible copper-clad laminate was observed using an optical microscope. The flow width (exudation width) of the epoxy adhesive was measured at 10 points and the arithmetic mean value was calculated. The conformability of the release film was evaluated according to the following evaluation criteria. The smaller the average value of the flow width of the epoxy adhesive, the more the adhesive is inhibited from flowing out, and the better the conformability to steps. In other words, a rating of A in the evaluation criteria can be said to indicate excellent conformability. - Evaluation criteria - A: The average value of the flow width of the epoxy adhesive was less than 55 μm. B: The average value of the flow width of the epoxy adhesive was 55 μm or more.

[0122] [Wrinkle resistance (wrinkle suppression)] A flexible copper-clad laminate (width 100 mm x length 200 mm, conductor width L = 100 μm / conductor gap S = 100 μm, polyimide thickness 25 μm, copper foil thickness 35 μm) and a coverlay film (width 100 mm x length 200 mm, polyimide thickness 25 μm, epoxy adhesive layer thickness 35 μm) with a Φ1.0 mm opening were prepared, and the copper foil surface of the flexible copper-clad laminate and the epoxy adhesive layer of the coverlay film were laminated so as to be in contact with each other. Next, the release surface of the release film was laminated so as to be in contact with the coverlay film, and heated and pressurized under conditions of a temperature of 180 ° C., a pressure of 3.0 MPa, vacuuming for 5 seconds, and pressure for 2 minutes to produce a laminate. After removing the laminate from the press, the release film was peeled off, and the surfaces of the release film and the flexible copper-clad laminate / coverlay film laminate were visually inspected to evaluate the wrinkle resistance of the release film according to the following evaluation criteria. Evaluation criteria A indicates excellent wrinkle resistance. -Evaluation criteria- A: No wrinkles were observed in the release film, flexible copper-clad laminate, or coverlay film. B: Wrinkles were observed in the release film, and the wrinkles were also transferred to the flexible copper-clad laminate and / or coverlay film.

[0123] Example 2 A resin composition (X) was prepared in the same manner as in Example 1, except that 80 parts by mass of polybutylene terephthalate (A-1) and 20 parts by mass of pellets containing copolymer (B-1) were used as the components of the resin composition (X). A release film was then produced from the composition, and the film-forming properties, physical properties of the release film, and press molding properties were evaluated. The results are shown in Table 2.

[0124] Example 3 A resin composition (X) was prepared in the same manner as in Example 1, except that 80 parts by mass of polybutylene terephthalate (A-1) and 20 parts by mass of pellets containing copolymer (B-2) were used as the components of the resin composition (X). A release film was then produced from the composition, and the film formability, physical properties of the release film, and press molding properties were evaluated. The results are shown in Table 2.

[0125] Example 4 A resin composition (X) was prepared in the same manner as in Example 1, except that 60 parts by mass of polybutylene terephthalate (A-1) and 40 parts by mass of pellets containing copolymer (B-1) were used as the components of the resin composition (X). A release film was then produced from the composition, and the film-forming properties, physical properties of the release film, and press molding properties were evaluated. The results are shown in Table 2.

[0126] Example 5 A resin composition (X) was prepared in the same manner as in Example 1, except that 60 parts by mass of polybutylene terephthalate (A-1) and 40 parts by mass of pellets containing copolymer (B-2) were used as the components of the resin composition (X). A release film was then produced from the composition, and the film-forming properties, physical properties of the release film, and press molding properties were evaluated. The results are shown in Table 2.

[0127] Example 6 A resin composition (X) was prepared in the same manner as in Example 1, except that 10 parts by mass of a polyester elastomer (D) (Hytrel 7247 manufactured by Toray Celanese Co., Ltd.: melting point (Tm) 216°C) was used per 100 parts by mass of a total of 90 parts by mass of polybutylene terephthalate (A-1) and 10 parts by mass of pellets containing copolymer (B-1) as the components of the resin composition (X). A release film was then produced from the composition, and evaluations of film formability, physical properties of the release film, and press molding were performed. The results are shown in Table 2.

[0128] Example 7 A resin composition (X) was prepared in the same manner as in Example 1, except that 10 parts by mass of a styrene-based elastomer (E) (Tuftec M1943 manufactured by Asahi Kasei Corporation: maleic anhydride-modified SEBS, maleic anhydride addition rate of 1.8% by mass, styrene content of 20% by mass, MFR = 6.5 g / 10 min (230°C, 2.16 kgf)) was used per 100 parts by mass of a total of 90 parts by mass of polybutylene terephthalate (A-1) and 10 parts by mass of pellets containing copolymer (B-1) as the components of the resin composition (X). A release film was then produced from the composition, and the film formability, physical properties of the release film, and press molding properties were evaluated. The results are shown in Table 2.

[0129] Example 8 A resin composition (X) was prepared in the same manner as in Example 1, except that polybutylene terephthalate (A-2) was used as a constituent component of the resin composition (X) in Example 6. A release film was then produced from the composition, and the film formability, physical properties of the release film, and press molding properties were evaluated. The results are shown in Table 2.

[0130] Comparative Example 1 A resin composition (X) was prepared in the same manner as in Example 1, except that only 100 parts by mass of polybutylene terephthalate (A-1) was used as a constituent component of the resin composition (X). A release film was then produced from the composition, and evaluations of film formability, physical properties of the release film, and press molding were performed. The results are shown in Table 2. Note that no peak was observed in the waveform of the loss tangent tanδ of the solid viscoelasticity measured by the above-mentioned method at 20 to 35°C. Therefore, the maximum value of the loss tangent tanδ in the range of 20 to 35°C is shown.

[0131] Comparative Example 2 A resin composition (X) was prepared in the same manner as in Example 1, except that 80 parts by mass of polybutylene terephthalate (A-1) and 20 parts by mass of a polypropylene-ethylene random copolymer (manufactured by ExxonMobil Chemical Corporation, product name: Vistamaxx 6102: MFR = 3.0 g / 10 min (230°C, 2.16 kgf), ethylene content 16% by weight) were used as the components of the resin composition (X). A release film was then produced from the composition, and the film formability, physical properties of the release film, and press molding properties were evaluated. The results are shown in Table 2. Note that no peak was observed in the waveform of the loss tangent tanδ of the solid viscoelasticity measured at 20 to 35°C by the method described above. Therefore, the maximum value of the loss tangent tanδ in the range of 20 to 35°C is shown.

[0132] Comparative Example 3 A resin composition (X) was prepared in the same manner as in Example 1, except that 40 parts by mass of polybutylene terephthalate (A-1) and 60 parts by mass of pellets containing copolymer (B-1) were used, and then a release film was produced from the composition, and the film formability, physical properties of the release film, and press molding properties were evaluated. The results are shown in Table 2.

[0133] Comparative Example 4 A resin composition (X) was prepared in the same manner as in Example 1, except that 40 parts by mass of polybutylene terephthalate (A-1) and 60 parts by mass of pellets containing copolymer (B-2) were used, and then a release film was produced from the composition, and the film formability, physical properties of the release film, and press molding properties were evaluated. The results are shown in Table 2.

[0134]

[0135] It can be seen that the release films of Examples 1 to 8 have superior conformability and wrinkle resistance compared to Comparative Examples 1 and 2. On the other hand, Comparative Example 1, which was composed solely of polybutylene terephthalate (A-1), had excellent release properties, but no behavior was observed in which the loss tangent tanδ of the solid viscoelasticity showed a peak value in the range of 20 to 35°C measured under the conditions of tensile mode, frequency 1.0 Hz, heating rate 3°C / min, and strain 0.1%. Therefore, it can be seen that the release film of Comparative Example 1 has insufficient conformability, and wrinkles in the release film are directly transferred to the FPC, preventing the production of high-quality FPCs. Furthermore, Comparative Example 2, which contained a polyolefin elastomer (C) instead of the copolymer (B), did not satisfy all of the requirements for release properties, conformability, and wrinkle resistance.

[0136] Since copolymer (B-1) is an amorphous polymer and copolymer (B-2) has a melting point of 130°C, its heat resistance is insufficient. Therefore, the release films of Comparative Examples 3 and 4, which have a higher blend ratio of copolymer (B) than polybutylene terephthalate (A-1) or (A-2), have poor releasability and tend to stick to FPCs. Furthermore, the release films of Comparative Examples 3 and 4, which have a higher blend ratio of copolymer (B) than polybutylene terephthalate (A-1) or (A-2), have a higher thermal shrinkage rate and are prone to wrinkling. Furthermore, the release film of Example 6 has a smaller surface roughness than Comparative Examples 2 to 4, indicating improved film surface smoothness. The release film of Example 7 has a larger film width during film formation than Comparative Examples 1 to 4, indicating excellent suppression of the neck-in phenomenon during film formation.

[0137] The release film formed from the resin composition according to the present invention has excellent conformability to the fine steps (concave and convex shapes) of FPCs, thereby suppressing the outflow of adhesive, suppressing the occurrence of wrinkles, and exhibiting excellent releasability, and therefore can be suitably used as a release film for the printed wiring board manufacturing process. Furthermore, by utilizing the press molding or other FPC manufacturing process, it brings about high quality and high productivity, and is highly useful in various fields such as the electric / electronic parts industry, the machinery industry, and the automobile industry.

Claims

1. A resin composition (X) comprising: 50 to 95 parts by mass of polybutylene terephthalate (A); and 5 to 50 parts by mass of a 4-methyl-1-pentene / α-olefin copolymer (B) satisfying the following requirement (Ba) (with the proviso that the total of the polybutylene terephthalate (A) and the 4-methyl-1-pentene / α-olefin copolymer (B) is 100 parts by mass); Requirement (Ba): Consists of 60 to 90 mol % of a structural unit (i) derived from 4-methyl-1-pentene and 10 to 40 mol % of a structural unit (ii) derived from an α-olefin having 2 to 4 carbon atoms (with the proviso that the total of the structural units (i) and (ii) is 100 mol %).

2. Resin composition (X) described in claim 1, in which the content of at least one elastomer selected from the group consisting of polyester-based elastomer (D) and styrene-based elastomer (E) is 0 to 30 parts by mass per 100 parts by mass of the resin composition.

3. The resin composition (X) according to claim 1 or 2, wherein the 4-methyl-1-pentene / α-olefin copolymer (B) further satisfies the following requirement (B-b): the melting point (Tm) measured by a differential scanning calorimeter (DSC) is not observed or is in the range of less than 160°C.

4. The resin composition (X) according to claim 1 or 2, wherein the 4-methyl-1-pentene / α-olefin copolymer (B) further satisfies the following requirement (Be): the intrinsic viscosity [η] measured in decalin solvent at 135°C is in the range of 0.8 to 3.0 dl / g.

5. The resin composition (X) according to claim 1 or 2, wherein the 4-methyl-1-pentene / α-olefin copolymer (B) further satisfies the following requirement (B-g): the molecular weight distribution (Mw / Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC), is in the range of 1.5 to 3.

0.

6. The melt volume flow rate (MVR) of the polybutylene terephthalate (A) measured under conditions of a temperature of 250°C and a load of 2.16 kgf in accordance with JIS K7210-1 (2014) is 0.5 to 60 cm ３ The resin composition (X) according to claim 1 or 2, wherein the viscosity is in the range of 10 minutes or more.

7. The melt volume flow rate (MVR) of the polybutylene terephthalate (A) measured under conditions of a temperature of 250°C and a load of 2.16 kgf in accordance with JIS K7210-1 (2014) is 15 to 50 cm ３ The resin composition (X) according to claim 1 or 2, wherein the viscosity is in the range of 10 minutes or more.

8. The melt volume flow rate (MVR) of the polybutylene terephthalate (A) measured under conditions of a temperature of 250°C and a load of 2.16 kgf in accordance with JIS K7210-1 (2014) is 25 to 40 cm ３ The resin composition (X) according to claim 1 or 2, wherein the viscosity is in the range of 10 minutes or more.

9. Resin composition (X) according to claim 1 or 2, in which the content of at least one elastomer selected from the group consisting of polyester-based elastomer (D) and styrene-based elastomer (E) is 5 to 15 parts by mass per 100 parts by mass of the resin composition.

10. A molded article comprising the resin composition (X) according to claim 1 or 2.

11. A film comprising the resin composition (X) according to claim 1 or 2.

12. The film of claim 11 which is a monolayer film.

13. The film according to claim 11, having a critical surface tension at 23° C. of 20 to 30 mN / m.

14. The film according to claim 11, wherein the storage modulus E' of the solid viscoelasticity at 180°C is in the range of 10 to 90 MPa when measured under conditions of a tensile mode, a frequency of 1.0 Hz, a heating rate of 3°C / min, and a strain of 0.1%.

15. The film according to claim 11, which has a maximum value (tan δ peak value) of loss tangent tan δ of solid viscoelasticity at 20 to 35° C., measured under conditions of a tensile mode, a frequency of 1.0 Hz, a heating rate of 3° C. / min, and a strain of 0.1%, in the range of 0.02 to 0.

30.

16. The film of claim 11 which is a release film.

17. The film of claim 11 which is a release film for a printed wiring board manufacturing process.

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