Liquid crystal polymer film laminate, method for producing liquid crystal polymer film laminate, method for producing liquid crystal polymer film, and liquid crystal polymer film

Abstract

Provided is a liquid crystal polymer film laminate comprising a liquid crystal polymer film layer and a pair of support film layers laminated on both surfaces of the liquid crystal polymer film layer, wherein the support film layer is composed of a crystalline resin, and the dimensional change rate when the liquid crystal polymer film laminate is heated at a temperature within the range from 80°C below the melting point TmLCP of the liquid crystal polymer to the melting point TmLCP of the liquid crystal polymer is 0-2%.

Description

Liquid crystal polymer film laminate, method for manufacturing liquid crystal polymer film laminate, method for manufacturing liquid crystal polymer film, and liquid crystal polymer film

[0001] The present invention relates to a liquid crystal polymer film laminate, a method for producing a liquid crystal polymer film laminate, a method for producing a liquid crystal polymer film, and a liquid crystal polymer film.

[0002] Liquid crystal polymer films are known as polymer films used in electronic materials, boasting excellent heat resistance, low water absorption, and small dimensional change rates. Because liquid crystal polymer films also have excellent high-frequency characteristics and low dielectric constant, they are expected to be used in flexible printed wiring boards (FPCs) for fifth-generation mobile communication systems. Films used in flexible printed wiring boards may require solder heat resistance of 300°C or higher. Liquid crystal polymers that meet these requirements have melting points exceeding 300°C, necessitating high-temperature molding. However, liquid crystal polymers heated at high temperatures are prone to degradation, making molding difficult. Given this background, a method for obtaining heat-resistant liquid crystal polymer films is known in which a film is molded from a liquid crystal polymer with a low melting point and then heat-treated near the melting point of the liquid crystal polymer film, thereby obtaining a film made of a polymer with a melting point higher than that of the thermoplastic liquid crystal polymer (see, for example, Patent Document 1).

[0003] As described in the examples of Patent Document 1, heat treatment to improve the heat resistance of a liquid crystal polymer film requires heating for a long period of time at a temperature above the flow initiation temperature, which is near the melting point. Therefore, the technology described in Patent Document 1 has the problem that the liquid crystal polymer film deforms during heat treatment, causing deterioration in shape. Therefore, a method has been proposed in which the liquid crystal polymer film is laminated on a metal foil by thermocompression bonding or the like and then heat-treated (for example, Patent Document 2).

[0004] However, in the method of laminating a metal foil on a liquid crystal polymer film and then heat-treating it, the metal foil must be peeled off after the heat treatment. The adhesive strength between the thermocompression-bonded liquid crystal polymer film and the metal foil is high, and in some cases, the metal must be dissolved and removed using an acid or the like. Furthermore, if a laminate of a liquid crystal polymer film and a metal foil is produced and then heat-treated, and the heat-treated laminate is used as a flexible printed wiring board as is, it would seem that peeling off the metal foil after the heat treatment is unnecessary. However, from the perspective of mass production, the heat treatment of the laminate must be performed in a batch manner while the laminate is wound into a roll. To wind the laminate into a roll, metal foil must be laminated on both sides of the liquid crystal polymer film to prevent the liquid crystal polymer films from fusing together, so one of the metal foils must be peeled off after the heat treatment. Thus, the method of laminating a metal foil on a liquid crystal polymer film and then heat-treating it has the problem of needing to peel off the metal foil after the heat treatment.

[0005] Furthermore, a manufacturing method has been proposed for preventing fusion of liquid crystal polymer films wound into a roll after heat treatment after thermocompression bonding of a metal foil to a liquid crystal polymer film (Patent Document 3). In the technology described in Patent Document 3, a laminate roll (a roll wound under a predetermined tension by a winding device or the like) in which a laminate formed by thermocompression bonding a liquid crystal polymer film and a metal foil is wound is batchwise heat-treated, and at least the winding start end of the laminate is heat-treated in a state where it is not subjected to contact pressure from the outer laminate surface and the winding core surface. However, this method requires that the laminate film be wound into a roll so that it does not come into contact with the film, which not only reduces productivity but also deteriorates the shape of the film during heat treatment.

[0006] Furthermore, a method has also been proposed in which, when producing a liquid crystal polymer film by an inflation method, a multilayer film obtained by extruding a polymer having a higher melting point than the liquid crystal polymer film from a circular die is heat-treated by passing the extruded film through a heat treatment furnace or the like (Patent Document 4). However, the heat treatment time is short, ranging from 1 second to 15 minutes, and the heat treatment is insufficient. In addition, there is no mention of the liquid crystal polymer film being deformed during the heat treatment.

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 11-291329 Patent Document 2: Japanese Patent Application Laid-Open No. 2000-44797 Patent Document 3: Japanese Patent No. 5090308 Patent Document 4: Japanese Patent No. 3756836

[0008] An object of the present invention is to provide a liquid crystal polymer film laminate that can suppress deformation due to heat treatment and provide a heat-treated liquid crystal polymer film with excellent heat resistance, a method for producing the liquid crystal polymer film laminate, a method for producing a liquid crystal polymer film using the liquid crystal polymer film laminate, and a liquid crystal polymer film.

[0009] [1] According to a first aspect of the present invention, there is provided a liquid crystal polymer film laminate comprising a liquid crystal polymer film layer and a pair of support film layers laminated on both sides of the liquid crystal polymer film layer, wherein the support film layer is made of a crystalline resin, and the liquid crystal polymer film laminate is formed by heating the liquid crystal polymer to a melting point Tm ＬＣＰ -80°C to Tm ＬＣＰ The present invention provides a liquid crystal polymer film laminate having a dimensional change rate of 0% to -2% when heated at a temperature in the range of 100°C to 120°C.

[0010] [2] According to aspect 2 of the present invention, there is provided a liquid crystal polymer film laminate of aspect 1, in which when the liquid crystal polymer film laminate is deformed at a bending angle of 120° relative to the surface of one of the support film layers and then further deformed at a bending angle of 120° relative to the surface of the other support film layer, there is no peeling between the liquid crystal polymer film layer and the support film layer.

[0011] [3] According to a third aspect of the present invention, there is provided the liquid crystal polymer film laminate of the first or second aspect, wherein the crystalline resin constituting the support film layer is an aromatic polyether ketone or polyester.

[0012] [4] According to a fourth aspect of the present invention, there is provided a liquid crystal polymer film according to any one of the first to third aspects, wherein, in a pole measurement by X-ray diffraction of the liquid crystal polymer film obtained by peeling the support film from the liquid crystal polymer film laminate, the film is tilted 45° (α=45° in the Schulz method) and rotated in the in-plane direction (β direction) while measuring the diffraction intensity of the 110 plane, the integrated intensities at β=45 to 135°, 135° to 225°, 225 to 315°, and 315 to 45° are calculated, with β=0° as the longitudinal direction of the film, and the sum of the integrated intensity at β=45 to 135° and the integrated intensity at β=225° to 315° is defined as the longitudinal integrated intensity, and the sum of the integrated intensity at β=135 to 225° and the integrated intensity at β=315 to 45° is defined as the widthwise integrated intensity, the liquid crystal polymer film laminate has a degree of planar orientation represented by the following formula (1) of -0.5 or more and 0.5 or less: Planar orientation degree=(integrated intensity in the longitudinal direction−integrated intensity in the width direction) / (integrated intensity in the longitudinal direction+integrated intensity in the width direction) (1)

[0013] [5] According to a fifth aspect of the present invention, there is provided a method for producing a liquid crystal polymer film laminate according to any one of the first to fourth aspects, comprising: a laminate-forming step of obtaining a laminate in which a pair of support film layers are laminated on both sides of the liquid crystal polymer film layer; a stretching step of stretching the laminate in the longitudinal direction and / or the width direction; and a temperature T Ｒ and a relaxation step of performing a relaxation treatment under the conditions of T Ｒ１ ≦T Ｒ ≦T Ｒ２ (2) However, in the above formula (2), T Ｒ１ is the melting point Tm of the liquid crystal polymer ＬＣＰ represents a temperature of -50°C, and T Ｒ２ is the melting point Tm of the liquid crystal polymer ＬＣＰ Represents a temperature of +20°C.

[0014] [6] According to aspect 6 of the present invention, there is provided a method for producing a liquid crystal polymer film laminate of aspect 5, in which the amount of relaxation in the width direction of the laminate due to the relaxation treatment is -2% to -15%.

[0015] [7] According to aspect 7 of the present invention, there is provided a method for manufacturing a liquid crystal polymer film laminate of aspect 5 or 6, wherein the laminate formation step includes laminating a pair of the support film layers on both sides of the liquid crystal polymer film layer by pressure lamination or heat lamination.

[0016] [8] According to aspect 8 of the present invention, there is provided a method for producing a liquid crystal polymer film laminate according to any one of aspects 5 to 7, which includes a surface treatment step of applying a surface treatment to both sides of the liquid crystal polymer film layer and the surface of the support film layer that will be bonded to the liquid crystal polymer film layer before the laminate formation step.

[0017] [9] According to aspect 9 of the present invention, there is provided a method for producing a liquid crystal polymer film laminate of aspect 8, wherein the surface treatment is any one of a plasma treatment, a corona treatment, or a chemical conversion treatment.

[0018]

[10] According to aspect 10 of the present invention, there is provided a method for producing a liquid crystal polymer film laminate of aspect 5 or 6, wherein the laminate formation step includes producing the laminate by a melt extrusion method.

[0019]

[11] According to an eleventh aspect of the present invention, the liquid crystal polymer film laminate of any one of aspects 1 to 4 is provided with a temperature T Ｈ The present invention provides a method for producing a liquid crystal polymer film, which comprises a heat treatment step of performing heat treatment under the conditions of T Ｈ１ ≦T Ｈ ≦T Ｈ２ (3) However, in the above formula (3), T Ｈ１ is the melting point Tm of the liquid crystal polymer ＬＣＰ represents a temperature of -80°C, and T Ｈ２ is the melting point Tm of the liquid crystal polymer ＬＣＰ Represents.

[0020]

[12] According to aspect 12 of the present invention, there is provided a method for producing a liquid crystal polymer film according to aspect 11, in which the heat treatment step is carried out while the liquid crystal polymer film laminate is wound into a roll or while the liquid crystal polymer film laminate is stacked.

[0021]

[13] According to a thirteenth aspect of the present invention, in the method for producing a liquid crystal polymer film according to the eleventh or twelfth aspect, in the heat treatment step, the melting point Tm Ｈ－ＬＣＰ is the melting point Tm of the liquid crystal polymer before heat treatment ＬＣＰ There is provided a method for producing a liquid crystal polymer film, characterized in that heat treatment is carried out in the above-described manner.

[0022] According to the liquid crystal polymer film laminate of the present invention, it is possible to produce a liquid crystal polymer film that is suppressed from being deformed by heat treatment and has excellent heat resistance.

[0023] The liquid crystal polymer film laminate of the present invention is composed of a liquid crystal polymer film layer and a pair of support film layers laminated on both sides of the liquid crystal polymer film layer. In the liquid crystal polymer film laminate of the present invention, the support film layer is made of a crystalline resin. In addition, the liquid crystal polymer film laminate of the present invention is heated from room temperature to the melting point Tm of the liquid crystal polymer. ＬＣＰ -80°C to Tm ＬＣＰ The dimensional change rate is 0% to -2% when heated at a temperature in the range of 100°C to 1200°C. The liquid crystal polymer film laminate of the present invention is used to produce a liquid crystal polymer film by subjecting it to a heat treatment and then peeling off the support film layer.

[0024] <Liquid Crystal Polymer Film Layer> The liquid crystal polymer film layer used in the present invention is made of a liquid crystal polymer. The liquid crystal polymer is not particularly limited, but a liquid crystal polyester exhibiting thermotropic liquid crystal properties is preferred. Examples of such liquid crystal polyesters include aromatic polyesters synthesized from monomers such as aromatic diols, aromatic carboxylic acids, and hydroxycarboxylic acids, which exhibit liquid crystallinity when melted. Specific examples include polycondensates of ethylene terephthalate and parahydroxybenzoic acid, polycondensates of phenol, phthalic acid, and parahydroxybenzoic acid, and polycondensates of hydroxynaphthoic acid and parahydroxybenzoic acid. In particular, from the viewpoint of excellent mechanical properties, electrical properties, heat resistance, etc., aromatic polyester-based liquid crystal polymers having a basic structure of 6-hydroxy-2-naphthoic acid and its derivatives and at least one monomer component selected from the group consisting of parahydroxybenzoic acid, terephthalic acid, isophthalic acid, 6-naphthalenedicarboxylic acid, 4,4'-biphenol, bisphenol A, hydroquinone, 4,4-dihydroxybiphenol, ethylene terephthalate, and derivatives thereof are preferred. The liquid crystal polymers can be used alone or in any combination and ratio of two or more. The content of the liquid crystal polymer is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, and even more preferably 70 to 100% by mass, based on the total amount of the stretched liquid crystal polymer film.

[0025] The liquid crystal polyester can be synthesized by any known method, and is not particularly limited, including, for example, melt polymerization, melt acidolysis, slurry polymerization, etc. When these polymerization methods are used, acylation or acetylation may be carried out according to a conventional method.

[0026] The liquid crystal polymer may contain additives such as polymers such as fluororesins, polyolefins, polycycloolefins, polyetherimides, and silicone-modified polyetherimides, release improvers such as higher fatty acids having 10 to 25 carbon atoms, higher fatty acid esters, higher fatty acid amides, and higher fatty acid metal salts, chain extenders such as aliphatic carbodiimides, alicyclic carbodiimides, and aromatic carbodiimides, colorants such as dyes, pigments, and carbon black, organic fillers, inorganic fillers, hollow particles, antioxidants, heat stabilizers, light stabilizers, UV absorbers, flame retardants, lubricants, antistatic agents, surfactants, rust inhibitors, foaming agents, defoamers, and fluorescent agents, as long as the effects of the present invention are not excessively impaired. These polymers and additives can be added to the molten resin composition during film formation of the liquid crystal polymer film. These polymers and additives can be used alone or in combination of two or more. The content of the polymer or additive is not particularly limited, but from the viewpoint of moldability, thermal stability, etc., it is preferably 0.01 to 50 mass %, more preferably 0.1 to 40 mass %, and even more preferably 0.5 to 30 mass %, relative to the total amount of the liquid crystal polymer film layer.

[0027] The liquid crystal polymer film used as the liquid crystal polymer film layer can be produced by known methods. For example, a liquid crystal polymer can be formed into a film by melt extrusion film formation using a T-die (T-die melt extrusion). Specifically, a liquid crystal polymer film can be obtained by melt-kneading the liquid crystal polymer in an extruder, extruding the molten resin through a T-die, and solidifying it on a metal roll. When solidifying on a metal roll, touch molding using a rubber roll or a metal roll can also be used. The temperature of the extruder cylinder is preferably 230 to 360°C, more preferably 280 to 350°C. The slit spacing of the T-die can be appropriately set depending on the type and composition of the liquid crystal polymer used, the desired film performance, etc. The slit spacing of the T-die is not particularly limited, but is preferably 0.1 to 1.5 mm, more preferably 0.3 to 1.0 mm.

[0028] The thickness of the liquid crystal polymer film layer is not particularly limited, but from the viewpoint of handling and productivity during T-die melt extrusion molding, it is preferably 10 to 500 μm, more preferably 20 to 300 μm, and even more preferably 30 to 250 μm.

[0029] Melting point Tm of the liquid crystal polymer constituting the liquid crystal polymer film layer ＬＣＰ is preferably 250 to 380°C, more preferably 280 to 350°C. The glass transition temperature Tg of the liquid crystal polymer constituting the liquid crystal polymer film layer is preferably 80 to 150°C, more preferably 90 to 150°C, and even more preferably 90 to 120°C.

[0030] <Support Film Layer> The support film layer is a polymer film laminated on the liquid crystal polymer film layer to prevent the film layer from breaking when stretching the liquid crystal polymer film layer. The support film layer is made of a crystalline resin, and aromatic polyetherketone or polyester is preferably used as the crystalline resin. Specific examples of aromatic polyetherketones include polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), and polyetheretherketoneketone (PEEKK). Specific examples of polyesters include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT). These polymers can be used alone or in combination of two or more. Among them, polyetheretherketone (PEEK), polyethylene terephthalate (PET), and polybutylene terephthalate (PBT) are preferred, with polyetheretherketone (PEEK) being particularly preferred. By using a support polymer film made of such a support polymer, the laminate film can be stretched without breaking in the stretching step described below. Furthermore, a crystallized or stretched film is preferred as the support film, since it has high heat resistance and can be stretched at high temperatures.

[0031] The thickness of the support film layer is preferably 5 to 300 μm, more preferably 15 to 100 μm.

[0032] The support film layer used in the present invention preferably has the following characteristics: Ｓ１ or more, and temperature T Ｓ２ At any temperature in the following range, it is preferable that the total value of the yield load of the pair of support film layers is larger than the yield load of the liquid crystal polymer film layer. Ｓ１ is the glass transition temperature Tg of the liquid crystal polymer, and the temperature T Ｓ２ is the melting point Tm of the liquid crystal polymer ＬＣＰ and the melting point Tm of the crystalline resin constituting the support film Ｓ When the yield loads of the support film layer and the liquid crystal polymer film layer satisfy the above-mentioned relationship, as will be described later, when producing the liquid crystal polymer film laminate of the present invention, the laminate of the support film layer and the liquid crystal polymer film layer can be heated to a temperature above the melting point Tm ＬＣＰ At the following temperatures, the liquid crystal polymer film layer can be stretched at a stretching ratio of 2 or more without breaking.

[0033] Generally, when a laminate of a liquid crystal polymer film and a support film is stretched at a temperature below the melting point of the liquid crystal polymer, stress is concentrated in the liquid crystal polymer film, which may cause the film to break. To avoid this problem, conventional liquid crystal polymer film manufacturing techniques generally stretch the liquid crystal polymer in a molten state at a temperature above the melting point of the liquid crystal polymer.

[0034] In contrast, in the present invention, the relationship between the yield load of the support film layer and the yield load of the liquid crystal polymer film layer satisfies the above-mentioned condition, so that the laminate of the liquid crystal polymer film layer and the support film layer can be formed at a temperature lower than the melting point Tm ＬＣＰThe reason why the liquid crystal polymer film layer can be stretched at a temperature below its melting point when the yield loads of the liquid crystal polymer film layer and the support film layer satisfy the above relationship is not clear, but the following is thought to be the reason. ２ is the melting point Tm of the liquid crystal polymer ＬＣＰ That is, the melting point Tm of the liquid crystal polymer ＬＣＰ is the melting point Tm of the polymer constituting the support film Ｓ First, consider the case where the temperature is lower than -20°C. ＬＣＰ By heating the laminate of the support film layer and the liquid crystal polymer film layer in the following temperature range (for example, 150 to 280°C), the elastic modulus of the liquid crystal polymer falls below 1000 MPa, and soft portions are formed in the liquid crystal polymer film layer. ＬＣＰ In the following temperature range, the sum of the yield loads of the pair of support film layers exceeds the yield load of the liquid crystal polymer film layer. As a result, the stretching load applied when the laminate is stretched is supported by the support film layer. Therefore, even if the liquid crystal polymer film layer becomes thinner as a result of stretching and a portion where the load is reduced occurs, it is possible to prevent tensile stress from concentrating in the portion where the load is reduced. Furthermore, since the liquid crystal polymer film layer and the support film layer are in close contact with each other, as the support film layer is stretched, the stretching force is applied evenly to the liquid crystal polymer film layer through the interface with the liquid crystal polymer film layer. From the above, it is considered that the liquid crystal polymer film layer can be stretched without breaking. Note that at temperature T Ｓ２ is the melting point Tm of the crystalline resin constituting the support film Ｓ When the temperature is −20° C., that is, the melting point Tm of the crystalline resin constituting the support film Ｓ The temperature of -20°C is the melting point Tm of the liquid crystal polymer. ＬＣＰ It is believed that even if the stretching temperature is lower, the liquid crystal polymer film layer can be stretched without breaking for the same reason.

[0035] In addition, the temperature T Ｓ１ or more, and temperature T Ｓ２ It is preferable that the total value of the yield load of the pair of support film layers is greater than the yield load of the liquid crystal polymer film layer over the entire temperature range below. Ｓ２ is the melting point Tm of the liquid crystal polymer ＬＣＰ That is, the melting point Tm of the liquid crystal polymer ＬＣＰ is the melting point Tm of the polymer constituting the support film layer Ｓ When the temperature is lower than −20° C., for example, T Ｓ１ is 150°C, Tm ＬＣＰ is 280°C, Tm Ｓ When is 320°C, T Ｓ１ (150°C) ~ T Ｓ２ (280°C), the total value of the yield load of the pair of support film layers is preferably greater than the yield load of the liquid crystal polymer film layer. Ｓ２ is the melting point Tm of the polymer constituting the support film layer Ｓ When the temperature is −20° C., that is, the melting point Tm of the polymer constituting the support film layer Ｓ The temperature of -20°C is the melting point Tm of the liquid crystal polymer. ＬＣＰ If it is lower, for example, T Ｓ１ is 150°C, Tm ＬＣＰ is 310°C, Tm Ｓ When is 320°C, T Ｓ１ (150°C) ~ T Ｓ２ (300°C), the total value of the yield load of the pair of support film layers is preferably greater than the yield load of the liquid crystal polymer film layer. Ｓ１ or more, and temperature T Ｓ２ It is not necessary to satisfy the above relationship over the entire temperature range below. For example, when the laminate of the liquid crystal polymer film layer and the support film layer is heated to a temperature T Ｓ１ or higher and temperature T Ｓ２ When stretching is performed at a specific temperature within the following temperature range, the yield loads of the liquid crystal polymer film layer and the support film layer measured at the specific temperature may satisfy the above relationship.

[0036] The support film layer used in the present invention preferably has the following characteristics: Ｓ１ or more, and temperature T Ｓ２ At any temperature in the following range, it is preferable that the total value of the maximum point load of the pair of support film layers is larger than the maximum point load of the liquid crystal polymer film layer. This allows the laminate of the liquid crystal polymer film layer and the support film layer to be heated to the melting point Tm of the liquid crystal polymer when producing a liquid crystal polymer film laminate. ＬＣＰ The film can be stretched at the following temperatures, which can reduce the anisotropy of the liquid crystal polymer film that is finally obtained.

[0037] The support film layer used in the present invention is heated to a temperature T Ｓ１ or more, and temperature T Ｓ２ In the following temperature range, the breaking elongation is preferably 200% or more. It is sufficient that at least one of the two support film layers laminated on the liquid crystal polymer film layer has a breaking elongation of 200% or more. This allows the laminate of the liquid crystal polymer film layer and the support film layer to be heated to the melting point Tm of the liquid crystal polymer when producing the liquid crystal polymer film laminate of the present invention. ＬＣＰ The film can be stretched at the following temperatures, which can reduce the anisotropy of the liquid crystal polymer film that is finally obtained.

[0038] The yield load, maximum point load, and breaking elongation of the support film layer can be determined from a tensile test performed on the support film used as the support film layer to obtain an SS curve with stress on the vertical axis and elongation on the horizontal axis.

[0039] The liquid crystal polymer film layer and the support film layer must be in close contact with each other. The strength of the adhesion must be such that they do not peel when the liquid crystal polymer film laminate is heated. Specifically, when the liquid crystal polymer film laminate is deformed at a bending angle of 120° relative to the surface of one of the support film layers and then deformed at a bending angle of 120° relative to the surface of the other support film layer, it is preferable that there is no peeling between the liquid crystal polymer film layer and the support film layer. If the liquid crystal polymer film layer and the support film layer peel off in this method, there is a risk that the liquid crystal polymer film layer will deform or break when the liquid crystal polymer film laminate is heated.

[0040] The anisotropy of the molecular orientation of the liquid crystal polymer film obtained by peeling the support film from the liquid crystal polymer film laminate of the present invention preferably has a degree of planar orientation, as defined below, within a predetermined range. First, in pole measurement by X-ray diffraction, the liquid crystal polymer film is tilted 45° (α = 45° in the Schulz method) and rotated in the in-plane direction (β direction) while measuring the diffraction intensity of the 110 plane, to prepare an X-ray diffraction intensity profile. In this profile, the longitudinal direction of the film is defined as β = 0°, and the integrated intensities at β = 45 to 135°, 135 to 225°, 225 to 315°, and 315 to 45° are determined. The integrated intensity in the longitudinal direction is the sum of the integrated intensity at β = 45 to 135° and the integrated intensity at β = 225 to 315°. The integrated intensity in the width direction is defined as the sum of the integrated intensity at β = 135 to 225° and the integrated intensity at β = 315 to 45°. In this case, the degree of planar orientation represented by the following formula (1) is preferably -0.5 or more and 0.5 or less. The degree of planar orientation is preferably -0.3 or more and 0.3 or less, more preferably -0.2 or more and 0.2 or less. In addition, it is preferable that the degree of planar orientation after subjecting the liquid crystal polymer film laminate to a heat treatment described later satisfies the following formula (1): degree of planar orientation = (integrated intensity in the longitudinal direction - integrated intensity in the width direction) / (integrated intensity in the longitudinal direction + integrated intensity in the width direction) (1)

[0041] The diffraction intensity of the 110 plane is the diffraction intensity of the crystal plane (110 plane) of the liquid crystal polymer. For example, the diffraction intensity of the 110 plane of a liquid crystal polymer obtained by polycondensation of 2,6-hydroxynaphthoic acid and parahydroxybenzoic acid in a molar ratio of 73:27 is the largest diffraction intensity observed at 2θ=20° when X-ray diffraction is measured at a diffraction angle (2θ) range of 10° to 40°. The diffraction intensity of the (110 plane) of a liquid crystal polymer oriented in the longitudinal direction is greatest at β=90° and 270° when the longitudinal direction of the film is defined as β=0°. Therefore, the longitudinal integrated intensity is the sum of the integrated intensity at β=45° to 135° and the integrated intensity at β=225° to 315°, and the widthwise integrated intensity is the sum of the integrated intensity at β=135° to 225° and the integrated intensity at β=315° to 45°. The integrated intensity is calculated as the area when β is plotted on the horizontal axis and the diffraction intensity on the vertical axis. A positive value of the value expressed by the above formula (1) indicates that the molecular chains are oriented in the longitudinal direction, and a negative value indicates that they are oriented in the width direction.

[0042] By setting the value of the degree of planar orientation expressed by the above formula (1) to -0.5 or more and -0.5 or less, the anisotropy of the linear expansion coefficient of the liquid crystal polymer film of the present invention can be reduced, and therefore, when the liquid crystal polymer film is laminated with copper to form an FPC, deformation due to differences in linear expansion coefficients can be suppressed. This effect is particularly pronounced when the liquid crystal polymer film is subjected to heat treatment (described below). The value of the degree of planar orientation is preferably -0.2 to 0.2. Within this range, the linear expansion coefficient of the liquid crystal polymer film can be approximately 10 to 30 ppm in both the longitudinal and transverse directions of the film. Furthermore, by setting the value of the degree of planar orientation to -0.1 to 0.1, the linear expansion coefficient becomes even closer to the linear expansion coefficient of copper, 18 ppm.

[0043] <Method of Manufacturing Liquid Crystal Polymer Film Laminate> The liquid crystal polymer film laminate of the present invention includes a laminate forming step of obtaining a laminate in which a support film layer is laminated on both sides of a liquid crystal polymer film layer, a stretching step of stretching this laminate in the longitudinal direction and / or the width direction, and a temperature T Ｒ and a relaxation step of performing a relaxation treatment under the conditions of T Ｒ１ ≦T Ｒ ≦TＲ２ (2) However, in the above formula (2), T Ｒ１ is the melting point Tm of the liquid crystal polymer ＬＣＰ represents a temperature of -50°C, and T Ｒ２ is the melting point Tm of the liquid crystal polymer ＬＣＰ Represents a temperature of +20°C.

[0044] In the laminate formation step, a laminate of a liquid crystal polymer film layer and a support film layer is laminated by a pressure lamination method or a thermal lamination method. In the thermal lamination method, the liquid crystal polymer film layer and the support film layer are pressure-bonded while the laminate of the liquid crystal polymer film layer and the support film layer is heated by a pair of heated rolls. The conditions for the thermal lamination method can be appropriately selected according to the physical properties of the liquid crystal polymer and the crystalline resin constituting the support film layer. Although not particularly limited, the melting point Tm of the liquid crystal polymer is ＬＣＰ A temperature near the melting point Tm of the crystalline resin that constitutes the support film Ｓ It is preferable to carry out the heating and pressing at a temperature in the vicinity of the temperature.

[0045] Although not particularly limited, it is preferable to perform a surface treatment process before the laminate formation process, in which the surface of the liquid crystal polymer film layer that contacts the support film layer (the bonding surface) and the surface of the support film layer that contacts the liquid crystal polymer film layer (the bonding surface) are each subjected to a surface treatment. Examples of surface treatment methods include plasma treatment, in which electrical energy is applied to irradiate the surface with a gas that has been converted into a plasma state; corona treatment, in which the surface is activated by discharge; activation methods, in which the surface is irradiated with ultraviolet light or an electron beam; activation methods, in which a flame is applied to the surface; chemical treatment, in which the surface is oxidized using potassium dichromate or the like; and primer treatment, in which a primer is applied. By performing such surface treatment before bonding the liquid crystal polymer film layer and the support film layer, the adhesion between the liquid crystal polymer film layer and the support film layer can be improved. The surface treatment method can be appropriately selected depending on the physical properties of the liquid crystal polymer and the crystalline resin. However, plasma treatment, corona treatment, and chemical treatment are preferred, and plasma treatment is particularly preferred, from the viewpoint of improving the adhesion between the liquid crystal polymer film layer and the support film layer and reducing damage to the liquid crystal polymer film obtained from the liquid crystal polymer film laminate.

[0046] The method for forming the laminate in the laminate forming step is not particularly limited to the above. For example, a laminate of a liquid crystal polymer film layer and a support film layer may be produced by a melt extrusion method. Specifically, the liquid crystal polymer may be melted in a first extruder, and the crystalline resin may be melted in a second extruder, and the respective polymers may be extruded into a film shape so that a layer made of the crystalline resin is laminated on one or both sides of the layer made of the liquid crystal polymer, to form a laminate.

[0047] As a method for laminating a layer made of a crystalline resin on one or both sides of a layer made of a liquid crystal polymer, a method for forming a multilayer extrusion film from a T-die can be used.Specifically, there are a feed block method in which molten liquid crystal polymer and crystalline resin supplied from two extruders are fed to a feed block, merged, and then extruded into a film form from a T-die, and a multi-manifold method in which molten liquid crystal polymer and crystalline resin are separately fed to a T-die and extruded into a film form.From the viewpoint of improving the smoothness of the liquid crystal polymer film finally obtained, it is preferable to apply the multi-manifold method, taking into account the case where the viscosity or flow properties of the liquid crystal polymer and the crystalline resin when melted are different.

[0048] In the stretching step, the laminate of the liquid crystal polymer film layer and the support film layer obtained in the laminate formation step is stretched in the longitudinal direction and / or width direction. Stretching in the width direction (TD) is particularly preferred. Stretching the laminate in the width direction can reduce the anisotropy of the final liquid crystal polymer film. The method for stretching the laminate is not particularly limited, but a tenter transverse stretching method is preferred, in which both ends of the laminate are clamped with clips and heated and stretched. The stretching ratio and stretching speed are appropriately selected so that the support film layer can be stretched and the shape and physical properties of the liquid crystal polymer film layer after stretching are within the desired range. The stretching ratio is preferably 2 to 5 times. The stretching speed is preferably 1 to 10,000% / min, more preferably 50 to 5,000% / min, and even more preferably 500 to 4,000% / min. Furthermore, to adjust the degree of planar orientation after stretching, additional stretching in the longitudinal direction (MD) may be performed as needed.

[0049] The temperature at which the laminate of the liquid crystal polymer film layer and the support film layer is stretched is temperature T Ｓ１ or higher and temperature T Ｓ２ The temperature T Ｓ２ is the melting point Tm of the liquid crystal polymer ＬＣＰ That is, the melting point Tm of the liquid crystal polymer ＬＣＰ is the melting point Tm of the crystalline resin constituting the support film layer ＳWhen the temperature is lower than −20° C., the temperature during stretching is set to T Ｓ１ or more, and the melting point Tm of the liquid crystal polymer ＬＣＰ The temperature at which the laminate is stretched is preferably set to the melting point Tm of the liquid crystal polymer. ＬＣＰ By setting the temperature to the range below, the smoothness of the liquid crystal polymer film finally obtained can be improved, and the film can be formed without unevenness in thickness or streaks, and excellent in film formability can be obtained. Furthermore, the temperature at which the laminate is stretched is set to T Ｓ１ By setting the temperature to 100° C. or more, the liquid crystal polymer film layer is more easily stretched, which is more preferable. Ｓ１ or more, and the melting point Tm of the liquid crystal polymer ＬＣＰ At any temperature in the following range, the total value of the yield load of the pair of support film layers is greater than the yield load of the liquid crystal polymer film layer, so that the laminate of the liquid crystal polymer film layer and the support film layer can be formed at a temperature above the melting point Tm of the liquid crystal polymer. ＬＣＰ The laminate can be stretched at the following temperatures. The temperature when stretching the laminate refers to the temperature of the surface of the laminate when stretching. The temperature when stretching the laminate refers to the temperature of the surface of the laminate film when stretching. The temperature when stretching the laminate can be adjusted by appropriately setting the stretching speed and the furnace temperature of the stretching device.

[0050] In addition, the temperature T Ｓ２ is the melting point Tm of the polymer constituting the support film layer Ｓ When the temperature is −20° C., that is, the melting point Tm of the polymer constituting the support film layer Ｓ The temperature of -20°C is the melting point Tm of the liquid crystal polymer. ＬＣＰ If the temperature is lower than the glass transition temperature Tg of the liquid crystal polymer, the temperature during stretching is set to T Ｓ１ The melting point Tm of the polymer constituting the support film ＳThe temperature is preferably -20°C or lower, more specifically, it is preferably in the range of 120 to 320°C, and more preferably in the range of 150 to 230°C.

[0051] In the relaxation step, the stretched laminate is heated to a temperature T Ｒ Relaxation treatment is carried out under the conditions of T Ｒ１ ≦T Ｒ ≦T Ｒ２ (2) However, in the above formula (2), T Ｒ１ is the melting point Tm of the liquid crystal polymer ＬＣＰ represents a temperature of -50°C, and T Ｒ２ is the melting point Tm of the liquid crystal polymer ＬＣＰ Represents a temperature of +20°C.

[0052] The relaxation treatment is a treatment in which the stretched laminate is shrunk along the stretching direction under predetermined temperature conditions. For example, when a laminate of a liquid crystal polymer film layer and a support film layer is stretched in the width direction (TD direction) in the stretching step, the laminate is shrunk along the width direction in the relaxation step. The method of the relaxation treatment is not particularly limited, but for example, when the laminate is stretched by a tenter transverse stretching method, a method of appropriately reducing the distance between the tenter clips toward the downstream of the conveying direction of the stretched laminate can be mentioned. The relaxation amount in the width direction of the laminate by the relaxation treatment is preferably -2% to -15%, more preferably -5% to -12%, and even more preferably -10% to -12%. If the absolute value of the relaxation amount is too large, the film may bend in the width direction, resulting in a deterioration in shape. The relaxation amount is determined based on the width (W) of the laminate after the stretching step. １ ) to the width (W ２ ) decrease rate ((W ２ -W １ ) / W １ By subjecting the stretched laminate to a relaxation treatment, the residual stress in the laminate generated by the stretching step can be reduced, and therefore deformation and fusion of the laminate due to the heat treatment step described below can be suppressed. The relaxation treatment time is not particularly limited, and the relaxation treatment temperature T Ｒ and can be set appropriately depending on the amount of relaxation of the target.

[0053] In the above formula (2), T Ｒ１ is the melting point Tm of the liquid crystal polymer ＬＣＰ The temperature is −50° C., and preferably the melting point Tm ＬＣＰ The temperature is preferably −30° C., more preferably the melting point Tm ＬＣＰ The temperature is -10°C.

[0054] The temperature T Ｒ is the temperature of the surface of the laminate during the relaxation treatment. For example, when the stretching treatment is performed by the tenter transverse stretching method and then the relaxation treatment is performed, the temperature T Ｒ The temperature T Ｒ can be adjusted by appropriately adjusting the temperature inside the furnace of the stretching device during the relaxation treatment.

[0055] T Ｒ２ is the melting point Tm of the liquid crystal polymer ＬＣＰ +20°C, preferably Tm ＬＣＰ It is. T Ｒ２ is Tm ＬＣＰ Above +20°C, i.e., Tm ＬＣＰ If the relaxation treatment is carried out at a temperature exceeding +20° C., the shape of the liquid crystal polymer film deteriorates.

[0056] The relaxation treatment may be carried out until the target relaxation amount is reached, and the time for the relaxation treatment is not particularly limited, but is preferably 5 to 300 seconds, more preferably 10 to 200 seconds.

[0057] In this manner, a liquid crystal polymer film laminate can be obtained. In the liquid crystal polymer film laminate obtained in this manner, the liquid crystal polymer film laminate is heated to a temperature of 10 ... ＬＣＰ -80°C to Tm ＬＣＰ When heated at a temperature in the range of 0% to -2%, the dimensional change rate of the liquid crystal polymer film laminate before and after heating is 0% to -2%. ２ ) to the width (W ３ ) decrease rate (((W ３ -W２ ) / W ２ × 100[%]). The dimensional change rate is 0% to -2%, and preferably 0% to -1%. When the dimensional change rate due to heating is within the above range, deformation of the liquid crystal polymer film layer can be suppressed when the liquid crystal polymer film laminate of the present invention is subjected to a heat treatment. Although not particularly limited, heating the liquid crystal polymer film for 5 to 600 seconds makes it sufficiently possible to evaluate the dimensional change rate before and after heating.

[0058] <Method of Manufacturing Liquid Crystal Polymer Film> The liquid crystal polymer film of the present invention is formed by subjecting the liquid crystal polymer film laminate obtained by the above method to a temperature T Ｈ By subjecting the liquid crystal polymer film laminate to a heat treatment, a liquid crystal polymer film having excellent heat resistance can be produced. Ｈ１ ≦T Ｈ ≦T Ｈ２ (3) However, in the above formula (3), T Ｈ１ is the melting point Tm of the liquid crystal polymer ＬＣＰ represents a temperature of -80°C, and T Ｈ２ is the melting point Tm of the liquid crystal polymer ＬＣＰ Represents.

[0059] T Ｈ is the temperature of the liquid crystal polymer laminate during the heat treatment. Since the heat treatment time is long, the furnace temperature for heating the liquid crystal polymer laminate is usually set to the heat treatment temperature T Ｈ When a liquid crystal polymer film laminate is wound into a roll and then heat-treated, the outer side (outside) of the roll quickly reaches the furnace temperature after being placed in a furnace, while the inner side (inside) of the roll takes time to reach the furnace temperature. For this reason, it is preferable to adjust the heating time and temperature program so that the temperature and heating time are the same on the outer and inner sides of the roll.

[0060] T Ｈ is the melting point Tm of the liquid crystal polymer ＬＣＰ -80℃ (T Ｈ１ ) or more, and TmＬＣＰ If the temperature is lower than −80° C., the heat treatment time for improving the heat resistance of the liquid crystal polymer film becomes long, and productivity decreases. ＬＣＰ (T Ｈ２ If the temperature exceeds T, the liquid crystal polymer film will deform. Ｈ１ is the melting point Tm of the liquid crystal polymer ＬＣＰ The temperature is −80° C., and preferably the melting point Tm ＬＣＰ The temperature is -50°C.

[0061] The higher the heat treatment temperature, the faster the heat resistance can be improved, but the more likely the film is to deform or discolor. On the other hand, lowering the temperature makes it less likely that the film will deform or discolor, but the heat treatment time required to achieve the desired heat resistance will be longer, increasing production costs. The heat treatment temperature and time should be appropriately selected to achieve both film quality and production costs.

[0062] After the heat treatment step, the support film layer is peeled off to obtain the liquid crystal polymer film. Ｈ－ＬＣＰ (apparent melting point) is the Tm ＬＣＰ The melting point Tm of the liquid crystal polymer film after heat treatment is Ｈ－ＬＣＰ It is preferable to appropriately select the heat treatment temperature and time in the heat treatment step so that the melting point Tm of the liquid crystal polymer film is optimal depending on the application of the liquid crystal polymer film. For example, when the liquid crystal polymer film is used for a flexible printed wiring board, the melting point Tm Ｈ－ＬＣＰ is preferably 300°C or higher.

[0063] The liquid crystal polymer film obtained in this manner has excellent heat resistance and can be suitably used for circuit boards such as flexible printed wiring boards. The support film layer of the liquid crystal polymer film laminate may be peeled off immediately before the liquid crystal polymer film is used. The support film layer can serve as a protective film, for example, to prevent scratches during transportation.

[0064] Next, the present invention will be specifically explained by way of examples, but the present invention is not limited to these examples.

[0065] <Adhesion between Liquid Crystal Polymer Film Layer and Support Film Layer> A plate member was contacted with the surface of one of the support film layers of the obtained liquid crystal polymer film laminate, and the liquid crystal polymer film laminate was bent at a bending angle of 120° along the contact point of the plate member, deforming, and held for 5 seconds. After the plate member was released and the liquid crystal polymer film laminate returned to its original shape, a plate member was contacted with the surface of the other support film layer, and the laminate was similarly bent at a bending angle of 120° and held for 5 seconds. After the plate member was released and the liquid crystal polymer film laminate returned to its original shape, the presence or absence of peeling between the liquid crystal polymer film layer and the two support film layers was confirmed. ◯: No peeling occurred between the liquid crystal polymer film layer and the support film layer, and adhesion was excellent. ×: Peeling occurred between the liquid crystal polymer film layer and the support film layer, and adhesion was insufficient.

[0066] <Planar Orientation Degree of Film> A liquid crystal polymer film obtained by peeling off the support film from the heat-treated liquid crystal polymer film laminate was subjected to pole measurement using a horizontal sample multipurpose X-ray diffractometer (manufactured by Rigaku Corporation, model: Ultima IV) with a diffraction angle (2θ) fixed at 20°, an X-ray target of Cu, a voltage of 40 kV, a current of 40 mA, an α angle of 45°, and a β angle of 0 to 360° (the longitudinal direction of the film was 0°, and a step angle of 5°), to prepare an X-ray diffraction intensity profile. The integrated intensities of this profile at β=45 to 135°, 135° to 225°, 225 to 315°, and 315 to 45° were determined, and the sum of the integrated intensities at β=45 to 135° and β=225° to 315° was defined as the integrated intensity in the longitudinal direction, and the sum of the integrated intensities at β=135 to 225° and β=315 to 45° was defined as the integrated intensity in the width direction. The degree of planar orientation was calculated from the following formula (1): Degree of planar orientation=(integrated intensity in the longitudinal direction−integrated intensity in the width direction) / (integrated intensity in the longitudinal direction+integrated intensity in the width direction) (1)

[0067] <Melting point Tm of liquid crystal polymer ＬＣＰ , the melting point Tm of the liquid crystal polymer film Ｈ－ＬＣＰUsing a differential scanning calorimeter (manufactured by PerkinElmer, model: DSC8500), the prepared liquid crystal polymer film before lamination, or the liquid crystal polymer film obtained by peeling the support film layer from a laminated film consisting of a liquid crystal polymer layer and a support film layer, was analyzed according to the differential scanning calorimetric analysis method based on JIS K 7121. The endothermic peak temperature observed when the liquid crystal polymer film was heated from 0°C at a rate of 10°C / min was determined as the melting point Tm of the liquid crystal polymer. ＬＣＰ The endothermic peak temperature observed when the liquid crystal polymer film produced in each example was heated from 0°C at a rate of 10°C / min was taken as the melting point Tm of the liquid crystal polymer film. Ｈ－ＬＣＰ Melting point Tm Ｈ－ＬＣＰ The higher the value, the more excellent the heat resistance of the liquid crystal polymer film. In addition, the support film layer peeled from the laminate film consisting of the liquid crystal polymer layer and the support film layer was analyzed in the same manner, and the endothermic peak temperature observed when the temperature was increased from 0°C at a rate of 10°C / min was taken as the melting point of the support film layer.

[0068] <Glass Transition Temperature Tg of Liquid Crystal Polymer> Using a viscoelasticity measuring device (Hitachi High-Tech, model: DMA7100), the prepared liquid crystal polymer film before lamination, or the liquid crystal polymer film obtained by peeling the support film layer from a laminate film consisting of a liquid crystal polymer layer and a support film layer, was analyzed. When the liquid crystal polymer film was measured in a tensile mode (frequency 10 Hz) from 30 ° C. at 5 ° C. / min, the peak temperature of the loss tangent (tan δ) accompanying the change (decrease) in the storage modulus E' observed from 50 ° C. to 150 ° C. was taken as the glass transition temperature Tg of the liquid crystal polymer.

[0069] <Evaluation of Shape> The obtained liquid crystal polymer film was visually observed and rated as follows: Good: The film width was uniform and the surface was smooth. Deformation: The film was significantly deformed, especially in the width direction, and the film width was non-uniform.

[0070] Example 1 A liquid crystal polymer (LAPEROS A950RX, manufactured by Polyplastics Co., Ltd.) was fed into a twin-screw extruder (screw diameter 32 mm), extruded into a film form from a T-die (lip length 350 mm, lip clearance approximately 1 mm, die temperature 300°C) at the tip of the extruder, and cooled to obtain a liquid crystal polymer (LCP) film with a thickness of 200 μm to be used as a liquid crystal polymer film layer. This film was subjected to the above-mentioned method to obtain a melting point Tm ＬＣＰ The melting point Tm ＬＣＰ The glass transition temperature Tg was 95°C.

[0071] Next, both sides of the liquid crystal polymer film and one side of a polyether ether ketone (PEEK) film (manufactured by Victrex, APTIV Film 1000-025G, thickness 25 μm, surface roughness Ra=0.14 μm (MD), 0.12 μm (TD), melting point 340°C) serving as a support film layer were subjected to direct atmospheric pressure plasma treatment in an oxygen-containing gas atmosphere at a power of 1.5 kW and a conveying speed of 1.0 m / min. Next, the respective plasma-treated surfaces were overlapped, and PEEK films were thermocompression-bonded to both sides of the liquid crystal polymer film using a first roll heated to 305°C and a second roll heated to 120°C under conditions of a nip pressure of 0.2 MPa and a conveying speed of 0.5 m / min. The liquid crystal polymer film and PEEK film were in close contact after thermocompression bonding. From the measurement results of the liquid crystal polymer film and the physical properties of the PEEK film, Ts １ (Tg)=95℃, Ts ２ = 280 ° C., T Ｒ１ = 230 ° C., T Ｒ２ = 300°C.

[0072] A laminate of a liquid crystal polymer film and a PEEK film was stretched 3.5 times in the width direction (TD) at a conveying speed of 8 m / min (stretching speed 1667% / min) using a tenter-type transverse stretching machine (furnace temperature 320°C). The temperature of the laminate during stretching was 210°C. Next, at a furnace temperature of 280°C, the chuck spacing of the tenter was linearly reduced while the laminate was held by the tenter, and a relaxation treatment was performed for 120 seconds. The relaxation amount in the width direction of the laminate was -11%, and the temperature T of the laminate during the relaxation treatment ＲThe temperature was 280° C. A liquid crystal polymer film laminate was obtained in this manner. The liquid crystal polymer film laminate was evaluated for adhesion between the liquid crystal polymer film layer and the support film layer (PEEK film).

[0073] Next, the liquid crystal polymer film laminate was wound into a roll, and this liquid crystal polymer film laminate was heat-treated in an oven at 250°C for 24 hours. The dimensional change rate (width shrinkage) of the liquid crystal polymer film laminate before and after the heat treatment was -1%. Thereafter, the PEEK film was peeled off to obtain a liquid crystal polymer film, and the shape, the degree of planar orientation, and the melting point (Tm Ｈ－ＬＣＰ The results are shown in Table 1.

[0074] Examples 2 and 3 A liquid crystal polymer film laminate and a liquid crystal polymer film were obtained in the same manner as in Example 1, except that the temperature and time of the heat treatment were changed to the values ​​shown in Table 1, and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0075] Examples 4 to 7 Liquid crystal polymer film laminates and liquid crystal polymer films were obtained in the same manner as in Example 1, except that the relaxation treatment conditions were changed to those shown in Table 1, and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0076] Example 8 A liquid crystal polymer (LAPEROS C950RX, manufactured by Polyplastics Co., Ltd.) was fed into a twin-screw extruder (screw diameter 32 mm), extruded into a film form from a T-die (lip length 350 mm, lip clearance approximately 1 mm, die temperature 340°C) at the tip of the extruder, and cooled to obtain a liquid crystal polymer (LCP) film having a thickness of 200 μm to be used as a liquid crystal polymer film layer. This film was subjected to the above-mentioned method to obtain a melting point Tm ＬＣＰ The melting point Tm ＬＣＰ The temperature was 320°C.

[0077] Next, both sides of the liquid crystal polymer film and one side of a polyether ether ketone (PEEK) film (manufactured by Victrex, APTIV Film 1000-025G, thickness 25 μm, surface roughness Ra = 0.14 μm (MD), 0.12 μm (TD), melting point 340 ° C) serving as a support film layer were subjected to direct atmospheric pressure plasma treatment in an oxygen-containing gas atmosphere at a power of 1.5 kW and a conveying speed of 1.0 m / min. Next, the plasma-treated surfaces were overlapped, and PEEK films were thermocompression-bonded to both sides of the liquid crystal polymer film using a first roll heated to 305 ° C and a second roll heated to 120 ° C under conditions of a nip pressure of 0.2 MPa and a conveying speed of 0.5 m / min. After thermocompression bonding, the liquid crystal polymer film and PEEK film were in close contact.

[0078] A laminate of a liquid crystal polymer film and a PEEK film was stretched 3 times in the width direction (TD) at a conveying speed of 8 m / min (stretching speed 1333% / min) using a tenter-type transverse stretching machine (furnace temperature 330°C). The temperature of the laminate during stretching was 220°C. Next, at a furnace temperature of 280°C, the chuck spacing of the tenter was linearly reduced while the laminate was held by the tenter, and a relaxation treatment was performed for 120 seconds. The relaxation amount in the width direction of the laminate was -7%, and the temperature T of the laminate during the relaxation treatment Ｒ The temperature was 280° C. A liquid crystal polymer film laminate was obtained in this manner. The liquid crystal polymer film laminate was evaluated for adhesion between the liquid crystal polymer film layer and the support film layer (PEEK film).

[0079] Next, the liquid crystal polymer film laminate was wound into a roll, and this liquid crystal polymer film laminate was heat-treated in an oven at 280°C for 24 hours. The dimensional change rate of the liquid crystal polymer film laminate before and after the heat treatment was -1%. Thereafter, the PEEK film was peeled off to obtain a liquid crystal polymer film, and the shape, the degree of planar orientation, the melting point (Tm Ｈ－ＬＣＰ The results are shown in Table 1.

[0080] Example 9 A liquid crystal polymer (LAPEROS A950RX, manufactured by Polyplastics Co., Ltd.) was fed into a twin-screw extruder (screw diameter 32 mm), extruded into a film form from a T-die (lip length 350 mm, lip clearance approximately 1 mm, die temperature 300°C) at the tip of the extruder, and cooled to obtain an unstretched liquid crystal polymer film with a thickness of 200 μm. ＬＣＰ The melting point Tm and the glass transition temperature Tg were evaluated. ＬＣＰ The viscosity was 280°C and the glass transition temperature Tg was 95°C.

[0081] Next, both sides of the unstretched liquid crystal polymer film were subjected to direct atmospheric pressure plasma treatment under an oxygen-containing gas atmosphere at a power of 1.5 kW and a conveying speed of 1.0 m / min. Next, the adhesive layer surface of a biaxially stretched PET film (manufactured by Toyobo, A4300, thickness 38 μm, surface roughness Ra = 0.10 μm (MD), 0.12 μm (TD), melting point 250 ° C.) with an easy-adhesion layer as a support polymer film and the plasma-treated surface of the unstretched liquid crystal polymer film were superimposed, and a first roll heated to 200 ° C. and a second roll heated to 120 ° C. were used under conditions of a nip pressure of 0.2 MPa and a conveying speed of 0.5 m / min. The PET film was thermocompressed onto both sides of the unstretched liquid crystal polymer film. After thermocompression bonding, the unstretched liquid crystal polymer film and the PET film were in close contact.

[0082] The laminated film thus produced was stretched 3 times in the width direction (TD) using a tenter-type transverse stretching machine (furnace temperature 280°C) with a stretching zone length of 1.2 m and a conveying speed of 10 m / min (stretching speed 1667% / min). The temperature of the laminate during stretching was 150°C. Next, while the laminate was held in the tenter, the chuck spacing of the tenter was linearly reduced at a furnace temperature of 240°C, and a relaxation treatment was performed for 120 seconds. The relaxation amount in the width direction of the laminate was -6%, and the temperature T of the laminate during the relaxation treatment was 1.2 m. Ｒ The temperature was 240° C. In this manner, a liquid crystal polymer film laminate was obtained. The liquid crystal polymer film laminate was evaluated for adhesion between the liquid crystal polymer film layer and the support film layer (PEEK film).

[0083] Next, the liquid crystal polymer film laminate was wound into a roll, and this liquid crystal polymer film laminate was heat-treated in an oven at 240°C for 24 hours. Thereafter, the PEEK film was peeled off to obtain a liquid crystal polymer film, and the shape, the degree of planar orientation, and the melting point (Tm Ｈ－ＬＣＰ The results are shown in Table 1.

[0084] Example 10: A liquid crystal polymer (Polyplastics Co., Ltd., LAPEROS A950RX) was fed into a twin-screw extruder (screw diameter 26 mm) and melt-kneaded at 300 ° C. In addition, a polyether ether ketone (PEEK) polymer (Daicel-Evonik, VESTAKEEP 3300G) was fed into a single-screw extruder (screw diameter 40 mm) as a support polymer and melt-kneaded at 380 ° C. These molten polymers were fed into a multi-manifold T-die, and layers of support polymer were superimposed on both sides of a layer of liquid crystal polymer. By extruding and cooling, a laminated film with a liquid crystal polymer layer of 175 μm and support polymer layers on both sides of 30 μm each, for a total of 235 μm, was produced. The melting point of PEEK was 340 ° C.

[0085] The laminated film thus produced was stretched 3.5 times in the width direction (TD) using a tenter-type transverse stretching machine (furnace temperature 330°C) with a stretching zone length of 1.2 m and a conveying speed of 5 m / min (stretching speed 1042% / min). The temperature of the laminate during stretching was 260°C. Next, while the laminate was held in the tenter, the chuck spacing of the tenter was linearly reduced at a furnace temperature of 280°C, and a relaxation treatment was performed for 120 seconds. The relaxation amount in the width direction of the laminate was -11%, and the temperature T of the laminate during the relaxation treatment was 1.2 m. Ｒ The temperature was 280° C. A liquid crystal polymer film laminate was obtained in this manner. The liquid crystal polymer film laminate was evaluated for adhesion between the liquid crystal polymer film layer and the support film layer (PEEK film).

[0086] Next, the liquid crystal polymer film laminate was wound into a roll, and this liquid crystal polymer film laminate was heat-treated in an oven at 250°C for 24 hours. Thereafter, the PEEK film was peeled off to obtain a liquid crystal polymer film, and the shape, the degree of planar orientation, and the melting point (Tm Ｈ－ＬＣＰThe results are shown in Table 1.

[0087] Comparative Example 1 A liquid crystal polymer (LAPEROS A950RX, manufactured by Polyplastics Co., Ltd.) was fed into a twin-screw extruder (screw diameter 32 mm) and extruded into a film form from a T-die (lip length 350 mm, lip clearance approximately 1 mm, die temperature 300°C) at the tip of the extruder. The cooled liquid crystal polymer film was wound into a roll and placed in an oven, where it was heat-treated at 250°C for 24 hours. The heat-treated liquid crystal polymer film was evaluated in the same manner as in Example 1. The amount of shrinkage during heat treatment was calculated as the ratio of the reduction in the width of the liquid crystal polymer film after heat treatment to the width of the liquid crystal polymer film before heat treatment. The results are shown in Table 1.

[0088] <Comparative Example 2> A liquid crystal polymer film laminate was obtained in the same manner as in Example 1, except that the liquid crystal polymer film and the polyether ether ketone (PEEK) film as the support film layer were not subjected to atmospheric pressure plasma treatment. However, the liquid crystal polymer film and the PEEK film were not in close contact with each other, and holes and cracks were observed in the liquid crystal polymer film.

[0089] Comparative Example 3 A liquid crystal polymer film was obtained in the same manner as in Example 1, except that the relaxation treatment was not performed, and was evaluated in the same manner as in Example 1. The amount of shrinkage during heat treatment was calculated as the ratio of the reduction in the width of the liquid crystal polymer film after heat treatment to the width of the liquid crystal polymer film before heat treatment. The results are shown in Table 1.

[0090] Comparative Example 4: Relaxation treatment temperature T Ｒ A liquid crystal polymer film laminate and a liquid crystal polymer film were obtained in the same manner as in Example 1, except that the heating temperature was changed to 220° C., and the evaluations were similarly carried out. The results are shown in Table 1.

[0091] Comparative Example 5: Relaxation treatment temperature T Ｒ A liquid crystal polymer film laminate was obtained in the same manner as in Example 1, except that the temperature was changed to 310°C. However, the liquid crystal polymer melted after the relaxation treatment, and the shape deteriorated, so that subsequent evaluation was not possible.

[0092]

[0093] As shown in Table 1, a liquid crystal polymer film laminate having a pair of support film layers laminated on both sides of the liquid crystal polymer film is stretched and then relaxed to obtain the melting point Tm of the liquid crystal polymer. ＬＣＰ -80°C to Tm ＬＣＰ The liquid crystal polymer film obtained using the liquid crystal polymer film laminate having a dimensional change rate of 0% to -2% when heated at a temperature in the range of 0% to -2% had a good shape after heat treatment and was also excellent in heat resistance.

[0094] On the other hand, in Comparative Example 1, in which the heat treatment was carried out without laminating with a support film layer, the film was deformed by the heat treatment, resulting in the rolled films being fused together. Also, in Comparative Example 2, in which the liquid crystal polymer film and the PEEK film were not in close contact with each other, holes and cracks were observed in the liquid crystal polymer film of the obtained liquid crystal polymer film laminate. Furthermore, in Comparative Example 3, in which the relaxation treatment was not carried out, and in Comparative Example 4, in which the temperature T Ｒ is the melting point Tm of the liquid crystal polymer ＬＣＰ In Comparative Example 4, which was lower than −50° C., the melting point Tm ＬＣＰ -80°C to Tm ＬＣＰ The dimensional change rate when heated to a temperature in the range of 100°C to 120°C was less than -2%, and the width of the liquid crystal polymer film was significantly shrunk by the heat treatment, resulting in deformation of the liquid crystal polymer film.

[0095] In addition, the temperature T Ｒ is the melting point Tm of the liquid crystal polymer ＬＣＰ In Comparative Example 5, where the temperature was higher than +20° C., the liquid crystal polymer film melted after the relaxation treatment, and the shape was deteriorated.

Claims

1. A liquid crystal polymer film laminate comprising a liquid crystal polymer film layer and a pair of support film layers laminated on both sides of the liquid crystal polymer film layer, wherein the support film layer is made of a crystalline resin, and the liquid crystal polymer film laminate is heated to a melting point Tm of a liquid crystal polymer constituting the liquid crystal polymer film. ＬＣＰ -80°C to Tm ＬＣＰ A liquid crystal polymer film laminate having a dimensional change rate of 0% to -2% when heated at a temperature in the range of 100° C. to 150° C.

2. A liquid crystal polymer film laminate as described in claim 1, in which when the liquid crystal polymer film laminate is deformed at a bending angle of 120° relative to the surface of one of the support film layers and then deformed at a bending angle of 120° relative to the surface of the other support film layer, no peeling occurs between the liquid crystal polymer film layer and the support film layer.

3. A liquid crystal polymer film laminate according to claim 1 or 2, wherein the crystalline resin constituting the support film layer is an aromatic polyether ketone or polyester.

4. A liquid crystal polymer film laminate according to claim 1 or 2, wherein, in a pole measurement by X-ray diffraction of the liquid crystal polymer film obtained by peeling off the support film from the liquid crystal polymer film laminate, the film is tilted 45° (α=45° in the Schulz method) and rotated in the in-plane direction (β direction) while measuring the diffraction intensity of the 110 plane, the integrated intensities of β=45-135°, 135°-225°, 225-315°, and 315-45° are calculated with β=0° as the longitudinal direction of the film, the sum of the integrated intensity of β=45-135° and the integrated intensity of β=225°-315° is the integrated intensity in the longitudinal direction, and the sum of the integrated intensity of β=135-225° and the integrated intensity of β=315-45° is the integrated intensity in the transverse direction, and the degree of planar orientation represented by the following formula (1) is between -0.5 and 0.5: Planar orientation degree=(integrated intensity in the longitudinal direction−integrated intensity in the width direction) / (integrated intensity in the longitudinal direction+integrated intensity in the width direction) (1) 5. A method for producing a liquid crystal polymer film laminate according to claim 1 or 2, comprising the steps of: forming a laminate in which a pair of the support film layers are laminated on both sides of the liquid crystal polymer film layer to obtain a laminate; stretching the laminate in the longitudinal direction and / or the width direction; and heating the laminate to a temperature T Ｒ and a relaxation step of performing a relaxation treatment under the condition of T. Ｒ１ ≦T Ｒ ≦T Ｒ２ (2) In the above formula (2), T Ｒ１ is the melting point Tm of the liquid crystal polymer ＬＣＰ represents a temperature of −50° C., and T Ｒ２ is the melting point Tm of the liquid crystal polymer ＬＣＰ Represents a temperature of +20°C.

6. A method for producing a liquid crystal polymer film laminate according to claim 5, wherein the amount of relaxation in the width direction of the laminate due to the relaxation treatment is -2% to -15%.

7. A method for producing a liquid crystal polymer film laminate as described in claim 5, wherein the laminate formation process includes laminating a pair of the support film layers on both sides of the liquid crystal polymer film layer by pressure lamination or heat lamination.

8. A method for producing a liquid crystal polymer film laminate as described in claim 7, comprising, prior to the laminate formation step, a surface treatment step of applying a surface treatment to both sides of the liquid crystal polymer film layer and to the surface of the support film layer that will be bonded to the liquid crystal polymer film layer.

9. A method for producing a liquid crystal polymer film laminate according to claim 8, wherein the surface treatment is any one of a plasma treatment, a corona treatment, and a chemical conversion treatment.

10. A method for producing a liquid crystal polymer film laminate according to claim 5, wherein the laminate formation step includes producing the laminate by a melt extrusion method.

11. The liquid crystal polymer film laminate according to claim 1 or 2 is subjected to a temperature T Ｈ A method for producing a liquid crystal polymer film, comprising a heat treatment step in which heat treatment is performed under the conditions of T Ｈ１ ≦T Ｈ ≦T Ｈ２ (3) In the above formula (3), T Ｈ１ is the melting point Tm of the liquid crystal polymer ＬＣＰ represents a temperature of −80° C., and T Ｈ２ is the melting point Tm of the liquid crystal polymer ＬＣＰ Represents.

12. A method for producing a liquid crystal polymer film according to claim 11, wherein the heat treatment step is carried out while the liquid crystal polymer film laminate is wound in a roll or while the liquid crystal polymer film laminate is stacked.

13. The method for producing a liquid crystal polymer film according to claim 11, wherein in the heat treatment step, the melting point Tm of the liquid crystal polymer film after the heat treatment is Ｈ－ＬＣＰ is the melting point Tm of the liquid crystal polymer before heat treatment ＬＣＰ The method for producing a liquid crystal polymer film is characterized by carrying out heat treatment in such a manner as described above.

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