LCP extrusion film, insulating material for circuit boards, and metal foil laminates

Abstract

Provided are: a new LCP extruded film having a high metal foil peel strength; an insulating material for a circuit board and a metal foil clad laminate that use the LCP extruded film; a new production method for an LCP extruded film having a high metal foil peel strength; and the like. This LCP extruded film has a film surface S1 and contains a thermoplastic liquid crystal polymer. The contact angle σ1 of the film surface S1 of the LCP extruded film with respect to water is 60-80° one day after undergoing a constant-temperature and constant-humidity treatment at 23°C and 50%RH. The contact angle σ7 of the film surface S1 of the LCP extruded film with respect to water is 60-80° seven days after undergoing the constant-temperature and constant-humidity treatment at 23°C and 50%RH. The reduction ratio ((σ7 - σ1) / σ1) of the contact angle σ7 with respect to the contact angle σ1 is at most 10.0%.

Description

[Technical field]

[0001] The present invention relates to an LCP extruded film, an insulating material for circuit boards, a metal foil-clad laminate, and the like. [Background technology]

[0002] Conventionally, as an insulating material for circuit boards, a varnish-impregnated composite material is known, which is obtained by impregnating a glass cloth with a varnish containing a thermosetting resin such as an epoxy resin, an inorganic filler, a solvent, etc., and then hot press molding the glass cloth. However, this manufacturing method has poor process tolerance during manufacturing, and is inferior in productivity, from the viewpoint of, for example, the resin flow during varnish impregnation and the hardening property during hot press molding. In addition, thermosetting resins are prone to absorbing moisture, and the dimensions change with the moisture absorption, so the dimensional accuracy (heated dimensional accuracy) of the obtained varnish-impregnated composite material is inferior.

[0003] On the other hand, liquid crystal polymers (LCPs) are polymers that exhibit liquid crystallinity in a molten state or in a solution state. In particular, thermotropic liquid crystal polymers that exhibit liquid crystallinity in a molten state can be extrusion molded, and have excellent properties such as high gas barrier properties, high film strength, high heat resistance, high insulation, low water absorption, and low dielectric properties in the high frequency range. For this reason, films using thermoplastic liquid crystal polymers are being considered for practical use in gas barrier film material applications, electronic material applications, and electrical insulating material applications.

[0004] However, when actually performing single-layer extrusion molding, it was found that due to the high degree of liquid crystal orientation possessed by thermoplastic liquid crystal polymers, it was difficult to obtain a thermoplastic liquid crystal polymer film that has high industrial value, i.e., a thermoplastic liquid crystal polymer film that has excellent thickness accuracy and good appearance and surface flatness.

[0005] For example, Patent Document 1 discloses a method for producing a liquid crystal film using a three-layer co-extrusion die, in which an intermediate layer is a thermotropic liquid crystal resin layer containing an aromatic polyester liquid crystal resin, and an outer layer is a thermoplastic resin layer containing a polypropylene resin or a polyethylene, and after each layer is simultaneously extruded through the three-layer co-extrusion die, the outer thermoplastic resin layer is peeled off and the intermediate liquid crystal resin layer is taken out and formed into a film. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 63-31729 Summary of the Invention [Problem to be solved by the invention]

[0007] Insulating materials for circuit boards using liquid crystal polymers have been in the limelight in recent years as insulating materials for circuit boards such as flexible printed circuit boards (FPCs), flexible printed circuit board laminates, and fiber-reinforced flexible laminates in the fifth generation mobile communication system (5G) and millimeter wave radars that will be developed in the future, due to their excellent high frequency characteristics and low dielectric properties. Specifically, in the application of insulating materials for circuit boards, a thermoplastic liquid crystal polymer film may be used as a metal foil-clad laminate by thermocompression bonding a metal foil such as copper foil to one side and / or both sides. Then, this metal foil is pattern-etched to form fine wiring, etc., so that the metal foil-clad laminate can be used as a material for circuit boards such as electronic circuit boards and multilayer boards. In this application, high adhesion between the thermoplastic liquid crystal polymer film and the metal foil and high copper foil peel strength are required.

[0008] The technology described in the above-mentioned Patent Document 1 is said to be capable of realizing a thermoplastic liquid crystal polymer film with excellent thickness accuracy and good appearance and surface flatness. However, when the use of the thermoplastic liquid crystal polymer film as an insulating material for a metal foil-clad laminate was actually examined, it was found that the technology described in Patent Document 1 did not provide sufficient adhesion between the thermoplastic liquid crystal polymer film and the metal foil, making it difficult to obtain high metal foil peel strength. Here, in order to improve the adhesion between the thermoplastic liquid crystal polymer film and the metal foil, it is also possible to subject the thermoplastic liquid crystal polymer film to various known physical surface treatments, such as oxygen plasma treatment, ozone treatment, or corona discharge treatment. However, the effect of improving adhesion by these surface treatments is temporary and decreases significantly over time after treatment. Therefore, in order to obtain high copper foil peel strength by these surface treatments, it is necessary to quickly press the thermoplastic liquid crystal polymer film and the copper foil after the surface treatment, taking into account deterioration over time.

[0009] The present invention has been made in view of the above problems, and an object of the present invention is to provide a novel LCP extruded film having high metal foil peel strength, an insulating material for circuit boards and a metal foil-clad laminate using the same, and a novel method for producing an LCP extruded film having high metal foil peel strength. [Means for solving the problem]

[0010] As a result of intensive research aimed at solving the above problems, the inventors have produced a new LCP extrusion film that exhibits little deterioration in the wettability of its film surface over time, and have discovered that this LCP extrusion film has high metal foil peel strength, thereby completing the present invention.

[0011] That is, the present invention provides various specific embodiments as shown below. (1) An LCP extruded film comprising a thermoplastic liquid crystal polymer having a film surface S1, wherein after one day of constant temperature and humidity treatment at 23°C and 50% RH, the film surface S1 of the LCP extruded film has a contact angle σ1 with water of 60° or more and 80° or less, and after seven days of constant temperature and humidity treatment at 23°C and 50% RH, the film surface S1 of the LCP extruded film has a contact angle σ7 with water of 60° or more and 80° or less, and the attenuation rate of the contact angle σ7 relative to the contact angle σ1 ((σ7-σ1) / σ1) is 10.0% or less.

[0012] (2) The extruded LCP film according to (1), wherein the extruded LCP film has a linear expansion coefficient in the MD direction and the TD direction within a range of −30 to 55 ppm / K.

[0013] (3) An extruded LCP film according to (1) or (2), which is an outer layer, an intermediate layer, and an intermediate layer excluding both outer layers from a laminated extruded film having the outer layers.

[0014] (4) The extruded LCP film according to any one of (1) to (3), wherein the film surface S1 is untreated by any physical surface treatment.

[0015] (5) The extruded LCP film according to any one of (1) to (4), having a thickness of 15 μm or more and 300 μm or less, wherein the hardness H1 at a point 1 μm deep in the thickness direction from the film surface S1 and the hardness H2 at the center point of the thickness, measured by a nanoindentation method on a film cross section parallel to the MD direction, satisfy -10.0≦100×(H2-H1) / H1≦0.0, and the linear expansion coefficients in the MD and TD directions of the extruded LCP film at 23 to 200° C., measured by a TMA method in accordance with JIS K7197, are within the ranges of -30 to 55 ppm / K.

[0016] (6) The extruded LCP film according to any one of (1) to (5), wherein the coefficient of linear expansion in the TD direction of the extruded LCP film is 0 to 55 ppm / K.

[0017] (7) The extruded LCP film according to any one of (1) to (6), which does not have a tape-peelable skin layer on the film surface S1 in an adhesion test by a cross-cut method in accordance with JIS K5600-5-6.

[0018] (8) The extruded LCP film according to any one of (5) to (7), wherein the hardness H2 at the center point of the thickness is 0.240 (GPa) or more.

[0019] (9) The extruded LCP film according to any one of (5) to (8), wherein the hardness H1 at the 1 μm depth point is 0.250 (GPa) or more.

[0020] (10) The extruded LCP film according to any one of (1) to (9), further comprising an inorganic filler.

[0021] (11) The extruded LCP film according to any one of (1) to (10), which is a T-die extruded film.

[0022] (12) An insulating material for circuit boards, comprising a laminate having at least the extruded LCP film according to any one of (1) to (11) and a woven fabric provided on at least one surface of the extruded LCP film.

[0023] (13) A metal foil-clad laminate comprising the extruded LCP film according to any one of (1) to (11) above and a metal foil provided on one and / or both sides of the extruded LCP film.

[0024] (14) A metal foil-clad laminate comprising a laminate having at least the LCP extruded film and woven fabric according to any one of (1) to (11) above, and a metal foil provided on one and / or both sides of the laminate.

[0025] (15) A step of co-extruding a first outer layer resin composition containing one or more thermoplastic resins selected from the group consisting of (meth)acrylic resins, polyamide resins, polybutylene terephthalate, polyethylene terephthalate, polycarbonate, polyether ether ketone, and polyphenyl sulfide, an intermediate layer resin composition containing a thermoplastic liquid crystal polymer, and a second outer layer resin composition containing one or more thermoplastic resins selected from the group consisting of (meth)acrylic resins, polyamide resins, polybutylene terephthalate, polyethylene terephthalate, polycarbonate, polyether ether ketone, and polyphenyl sulfide to obtain a co-extruded film having a laminated structure in which the first outer layer, the intermediate layer, and the second outer layer are arranged in this order; and and removing the first outer layer and the second outer layer from the co-extruded film to obtain the intermediate layer containing the thermoplastic liquid crystal polymer, wherein in the step of obtaining the intermediate layer, an LCP extruded film having a film surface S1 is obtained, wherein after 1 day of constant temperature and humidity treatment at 23°C and 50% RH, the film surface S1 of the LCP extruded film has a contact angle with water σ1 of 60° or more and 80° or less, and after 7 days of constant temperature and humidity treatment at 23°C and 50% RH, the film surface S1 of the LCP extruded film has a contact angle with water σ7 of 60° or more and 80° or less, and the attenuation rate of the contact angle σ7 relative to the contact angle σ1 ((σ7-σ1) / σ1) is 10.0% or less. Effect of the Invention

[0026] According to one aspect of the present invention, it is possible to realize a novel LCP extruded film having high metal foil peel strength, an insulating material for circuit boards and a metal foil-clad laminate using the same, and a novel method for producing an LCP extruded film having high metal foil peel strength. Also, according to one aspect of the present invention, it is possible to realize a novel LCP extruded film, an insulating material for circuit boards, a metal foil-clad laminate, etc., in which the anisotropy of the dimensional change rate is reduced compared to conventional products, and the dimensional change rates in the MD and TD directions are small. Therefore, according to various aspects of the present invention, it is possible to realize a highly reliable product that is adapted to recent ultra-fine processing. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a schematic perspective view showing an extruded LCP film of one embodiment. [Diagram 2] FIG. 2 is a diagram showing a calculation method for hardness measurement by the nanoindentation method. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing an extruded LCP film of one embodiment. [Figure 4] FIG. 4 is a conceptual diagram showing the principle of calculation of the degree of orientation based on the area ratio of the orientation peak. [Diagram 5] FIG. 5 is a diagram illustrating a co-extrusion process for an LCP extruded film according to one embodiment. [Figure 6] FIG. 6 is a diagram illustrating a co-extrusion process for an LCP extruded film according to one embodiment. [Figure 7] FIG. 7 is a diagram illustrating a co-extrusion process for an LCP extruded film according to one embodiment. [Figure 8] FIG. 8 is a schematic cross-sectional view showing an insulating material for circuit boards according to one embodiment. [Figure 9] FIG. 9 is a schematic cross-sectional view showing a metal foil-clad laminate of one embodiment. [Figure 10] FIG. 10 is a schematic cross-sectional view showing a metal foil-clad laminate of one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. The positional relationships such as up, down, left and right are based on the positional relationships shown in the drawings unless otherwise specified. The dimensional ratios of the drawings are not limited to the ratios shown. However, the following embodiments are examples for explaining the present invention, and the present invention is not limited to these. That is, the present invention can be practiced with any changes within the scope of the gist of the present invention. In this specification, for example, the expression of a numerical range such as "1 to 100" includes both the lower limit "1" and the upper limit "100". The same applies to the expression of other numerical ranges.

[0029] (LCP extrusion film) 1 is a schematic cross-sectional view showing a main part of an LCP extruded film 100 of this embodiment. The LCP extruded film 100 having a film surface S1 of this embodiment is obtained by extruding a thermoplastic liquid crystal polymer into a film shape, and is characterized in that the contact angle σ1 of the film surface S1 with water after one day of constant temperature and humidity treatment at 23° C. and 50% RH is 60° to 80°, the contact angle σ7 of the film surface S1 with water after seven days of constant temperature and humidity treatment at 23° C. and 50% RH is 60° to 80°, and the attenuation rate of the contact angle σ7 with respect to the contact angle σ1 ((σ7-σ1) / σ1) is 10.0% or less.

[0030] As the LCP extruded film 100, an extruded film such as a T-die extruded film is preferably used. As the LCP extruded film 100, a thermoplastic liquid crystal polymer layer that is an intermediate layer (core layer) of a three-layer coextruded film having a laminated structure in which a thermoplastic resin layer, a thermoplastic liquid crystal polymer layer, and a thermoplastic resin layer are arranged at least in this order is also preferably used. In this case, by removing the thermoplastic resin layers of both outer layers of the three-layer coextruded film, it can be used as a single-layer thermoplastic liquid crystal polymer film (LCP extruded film 100). Compared to woven fabrics or nonwoven fabrics made of thermoplastic liquid crystal polymer fibers, extruded films of thermoplastic liquid crystal polymers can be produced at low cost and with uniform quality.

[0031] The thermoplastic liquid crystal polymer contained in the LCP extruded film 100 may be any known one in the art, and the type is not particularly limited. The liquid crystal polymer is a polymer that forms an optically anisotropic molten phase, and a representative example is a thermotropic liquid crystal compound. The properties of the anisotropic molten phase can be confirmed by a known method, such as a polarized light inspection method using crossed polarizers. More specifically, the anisotropic molten phase can be confirmed by observing a sample placed on a Leitz hot stage at a magnification of 40 times under a nitrogen atmosphere using a Leitz polarizing microscope.

[0032] Specific examples of thermoplastic liquid crystal polymers include, but are not limited to, those obtained by polycondensation of monomers such as aromatic or aliphatic dihydroxy compounds, aromatic or aliphatic dicarboxylic acids, aromatic hydroxycarboxylic acids, aromatic diamines, aromatic hydroxyamines, and aromatic aminocarboxylic acids. The thermoplastic liquid crystal polymer is preferably a copolymer. Specific examples include, but are not limited to, aromatic polyamide resins obtained by polycondensation of monomers such as aromatic hydroxycarboxylic acids, aromatic diamines, and aromatic hydroxyamines; (all) aromatic polyester resins obtained by polycondensation of monomers such as aromatic diols, aromatic carboxylic acids, and aromatic hydroxycarboxylic acids; and the like. These can be used alone or in any combination and ratio of two or more.

[0033] Thermoplastic liquid crystal polymers are generally classified into I type, II type, III type, etc., from the viewpoint of heat distortion temperature (TDUL). Any type of thermoplastic liquid crystal polymer can be suitably used for the LCP extruded film 100 of the present embodiment, and may be appropriately selected depending on the application. For example, in electronic circuit board applications requiring application to lead-free solder at about 230 to 260°C, a highly heat-resistant I type thermoplastic liquid crystal polymer with a TDUL of about 250 to 350°C and a relatively heat-resistant II type thermoplastic liquid crystal polymer with a TDUL of about 240 to 250°C are suitably used.

[0034] Among these, (fully) aromatic polyester resins that exhibit thermotropic liquid crystal-like properties and have a melting point of 250°C or more, preferably 280°C to 380°C, are preferably used. As such (fully) aromatic polyester resins, for example, (fully) aromatic polyester resins that are synthesized from monomers such as aromatic diols, aromatic carboxylic acids, and hydroxycarboxylic acids and exhibit liquid crystallinity when melted are known. Representative examples include polycondensates of ethylene terephthalate and parahydroxybenzoic acid, polycondensates of phenol and phthalic acid and parahydroxybenzoic acid, and polycondensates of 2,6-hydroxynaphthoic acid and parahydroxybenzoic acid, but are not particularly limited thereto. The (fully) aromatic polyester resins can be used alone or in any combination and ratio of two or more. Depending on the required performance, a wholly aromatic polyester resin having a relatively high melting point or high heat distortion temperature and high heat resistance, or an aromatic polyester resin having a relatively low melting point or low heat distortion temperature and excellent moldability can be used.

[0035] A preferred embodiment is a (fully) aromatic polyester resin having a basic structure of 6-hydroxy-2-naphthoic acid and its derivatives (hereinafter, sometimes simply referred to as "monomer component A") 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 (hereinafter, sometimes simply referred to as "monomer component B"). In a molten state, such a (fully) aromatic polyester resin forms an anisotropic molten phase in which linear chains of molecules are regularly arranged, typically exhibiting thermotropic liquid crystal-like properties, and has excellent basic performance in terms of mechanical properties, electrical properties, high frequency properties, heat resistance, moisture absorption, and the like.

[0036] In addition, the (all) aromatic polyester resin of the above-mentioned preferred embodiment can have any structure as long as it has the monomer component A and the monomer component B as essential units. For example, it may have two or more kinds of the monomer component A, or it may have three or more kinds of the monomer component A. In addition, the (all) aromatic polyester resin of the above-mentioned preferred embodiment may contain another monomer component (hereinafter, simply referred to as "monomer component C") other than the monomer component A and the monomer component B. That is, the (all) aromatic polyester resin of the above-mentioned preferred embodiment may be a two-component or more polycondensate consisting of only the monomer component A and the monomer component B, or a three-component or more polycondensate consisting of the monomer component A, the monomer component B, and the monomer component C. Examples of the other monomer components include those other than the above-mentioned monomer component A and the monomer component B, specifically, aromatic or aliphatic dihydroxy compounds and derivatives thereof; aromatic or aliphatic dicarboxylic acids and derivatives thereof; aromatic hydroxycarboxylic acids and derivatives thereof; aromatic diamines, aromatic hydroxyamines, or aromatic aminocarboxylic acids and derivatives thereof; and the like, but are not particularly limited thereto. The other monomer components may be used either alone or in any combination and ratio of two or more kinds.

[0037] In this specification, the term "derivative" refers to a monomer component having a modification group such as a halogen atom (e.g., fluorine atom, chlorine atom, bromine atom, iodine atom), an alkyl group having 1 to 5 carbon atoms (e.g., methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, etc.), an aryl group such as a phenyl group, a hydroxyl group, an alkoxy group having 1 to 5 carbon atoms (e.g., methoxy group, ethoxy group, etc.), a carbonyl group, -O-, -S-, -CH2-, etc., introduced therein (hereinafter, this may be referred to as a "monomer component having a substituent"). Here, the "derivative" may be an ester-forming monomer such as an acylation product, an ester derivative, or an acid halide of the monomer components A and B which may have the above-mentioned modification group.

[0038] Particularly preferred embodiments include binary polycondensates of parahydroxybenzoic acid and its derivatives with 6-hydroxy-2-naphthoic acid and its derivatives; ternary or higher polycondensates of parahydroxybenzoic acid and its derivatives, 6-hydroxy-2-naphthoic acid and its derivatives, and monomer component C; and polycondensates of parahydroxybenzoic acid and its derivatives, 6-hydroxy-2-naphthoic acid and its derivatives, and terephthalic acid, isophthalic acid, 6-naphthalenedicarboxylic acid, 4,4'-biphenol, bisphenol A, hydroquinone, 4,4-dihydroxybiphenol. and ternary or higher polycondensates consisting of parahydroxybenzoic acid and its derivatives, 6-hydroxy-2-naphthoic acid and its derivatives, terephthalic acid, isophthalic acid, 6-naphthalenedicarboxylic acid, 4,4'-biphenol, bisphenol A, hydroquinone, 4,4-dihydroxybiphenol, ethylene terephthalate, and their derivatives, and one or more monomer components C. These can be obtained as having a relatively low melting point compared to, for example, homopolymers of parahydroxybenzoic acid, and therefore, thermoplastic liquid crystal polymers using these have excellent moldability when thermocompressed to an adherend.

[0039] From the viewpoint of lowering the melting point of the (all) aromatic polyester resin, improving the moldability during thermocompression bonding of the LCP extruded film 100 to an adherend, or obtaining high peel strength when the LCP extruded film 100 is thermocompression bonded to a metal foil, the molar ratio of the monomer component A to the (all) aromatic polyester resin is preferably 10 mol% or more and 90 mol% or less, more preferably 30 mol% or more and 85 mol% or less, and even more preferably 50 mol% or more and 80 mol% or less. Similarly, the molar ratio of the monomer component B to the (all) aromatic polyester resin is preferably 10 mol% or more and 90 mol% or less, more preferably 15 mol% or more and 70 mol% or less, and even more preferably 20 mol% or more and 50 mol% or less. In addition, the content of the monomer component C that may be contained in the (all) aromatic polyester resin is preferably 10 mol% or less, more preferably 8 mol% or less, even more preferably 5 mol% or less, and particularly preferably 3 mol% or less, in terms of molar ratio.

[0040] The (all) aromatic polyester resin can be synthesized by any known method, and is not particularly limited. Any known polycondensation method that forms an ester bond with the above-mentioned monomer components, such as melt polymerization, melt acidolysis, and slurry polymerization, can be used. When applying these polymerization methods, an acylation or acetylation step may be performed according to a conventional method.

[0041] The LCP extruded film 100 may further contain an inorganic filler. By containing an inorganic filler, it is possible to realize an LCP extruded film 100 with a reduced linear expansion coefficient, specifically, it is easy to obtain an LCP extruded film 100 with reduced anisotropy of the linear expansion coefficient in the MD direction, TD direction, and ZD direction (Z-axis direction; film thickness direction). Such an LCP extruded film 100 is particularly useful in rigid substrate applications requiring multi-layer lamination, for example.

[0042] The inorganic filler may be any of those known in the art, and the type is not particularly limited. For example, kaolin, calcined kaolin, calcined clay, uncalcined clay, silica (e.g., natural silica, fused silica, amorphous silica, hollow silica, wet silica, synthetic silica, aerosil, etc.), aluminum compounds (e.g., boehmite, aluminum hydroxide, alumina, hydrotalcite, aluminum borate, aluminum nitride, etc.), magnesium compounds (e.g., magnesium aluminometasilicate, magnesium carbonate, magnesium oxide, magnesium hydroxide, etc.), calcium compounds (e.g., calcium carbonate, Examples of the stannate include, but are not limited to, titanium oxide, zinc oxide, zirconium oxide, barium sulfate, zinc borate, barium metaborate, sodium borate, boron nitride, aggregated boron nitride, silicon nitride, carbon nitride, strontium titanate, barium titanate, and zinc stannate. These may be used alone or in combination of two or more. Among these, silica is preferred from the viewpoint of dielectric properties and the like.

[0043] The inorganic filler used here may be surface-treated as known in the art. The surface treatment can improve moisture resistance, adhesive strength, dispersibility, etc. Examples of surface treatment agents include, but are not limited to, silane coupling agents, titanate coupling agents, sulfonic acid esters, carboxylic acid esters, and phosphoric acid esters.

[0044] The median diameter (d50) of the inorganic filler can be appropriately set according to the required performance, and is not particularly limited. From the viewpoints of kneadability and handleability during preparation, the effect of reducing the linear expansion coefficient, etc., the d50 of the inorganic filler is preferably 0.01 μm to 50 μm, more preferably 0.03 μm to 50 μm, and even more preferably 0.1 μm to 50 μm. In this specification, the median diameter (d50) of the inorganic filler means a value measured on a volume basis by a laser diffraction / scattering method using a laser diffraction / scattering type particle size distribution measuring device (LA-500 manufactured by Horiba, Ltd.).

[0045] The content of the inorganic filler is not particularly limited and can be appropriately set according to the required performance, taking into consideration the blending balance with other essential components and optional components. From the viewpoints of kneading and handling during preparation, the effect of reducing the linear expansion coefficient, etc., the content of the inorganic filler is preferably 1% by mass or more and 45% by mass or less in total, more preferably 3% by mass or more and 40% by mass or less in total, and even more preferably 5% by mass or more and 35% by mass or less in total, calculated as solid content relative to the total amount of the LCP extruded film 100.

[0046] The LCP extruded film 100 may contain resin components other than the above-mentioned thermoplastic liquid crystal polymer (hereinafter, may be simply referred to as "other resin components"), such as thermosetting resins and thermoplastic resins, within a range that does not excessively impair the effects of the present invention. In addition, the LCP extruded film 100 may contain additives known in the art, such as release improvers such as higher fatty acids having 10 to 25 carbon atoms, higher fatty acid esters, higher fatty acid amides, higher fatty acid metal salts, polysiloxanes, and fluororesins; colorants such as dyes and pigments; organic fillers; antioxidants; heat stabilizers; light stabilizers; ultraviolet absorbers; flame retardants; antistatic agents; surfactants; rust inhibitors; defoamers; fluorescent agents, and the like, within a range that does not excessively impair the effects of the present invention. Each of these additives may be used alone or in combination of two or more. These additives may be included in the molten resin composition prepared when molding the LCP extruded film 100. The contents of these resin components and additives are not particularly limited, but from the viewpoints of molding processability, thermal stability, etc., they are preferably each 0.01 to 10 mass % relative to the total amount of 100 LCP extruded film, more preferably 0.1 to 7 mass %, and even more preferably 0.5 to 5 mass %.

[0047] The thickness of the LCP extruded film 100 can be appropriately set according to requirements and is not particularly limited. In consideration of handleability and productivity during extrusion molding, the thickness is preferably 15 μm to 300 μm, more preferably 18 μm to 250 μm, and even more preferably 20 μm to 200 μm.

[0048] Here, the film surface S1 of the LCP extruded film 100 has a contact angle σ1 with water after one day of constant temperature and humidity treatment at 23°C and 50%RH of 60° to 80°, preferably 60° to 78°, more preferably 60° to 75°. The film surface S1 of the LCP extruded film 100 has a contact angle σ7 with water after seven days of constant temperature and humidity treatment at 23°C and 50%RH of 60° to 80°, preferably 60° to 78°, more preferably 60° to 75°. The attenuation rate of the contact angle σ7 with respect to the contact angle σ1 ((σ7-σ1) / σ1) is 10.0% or less, preferably 9.0% or less, more preferably 8.5 or less. It goes without saying that the lower limit of the attenuation rate is 0%. The LCP extruded film 100 of the present embodiment has relatively small contact angles σ1 and σ7 with water as described above, and has high adhesion to metal foil, so that it can obtain a higher metal foil peel strength than conventional films. Furthermore, the LCP extruded film 100 of the present embodiment has a smaller deterioration over time of the contact angle with water (attenuation rate ((σ7-σ1) / σ1)) than films that have been subjected to physical surface treatments such as oxygen plasma treatment, ozone treatment, or corona discharge treatment, so that it can be subjected to a pressure bonding step with metal foil both immediately after production and after long-term storage.

[0049] In this specification, the contact angles σ1 and σ7 between the film surface S1 and water refer to values ​​calculated based on the tangent method using an automatic contact angle meter (DMC-MC3, manufactured by Kyowa Interface Science Co., Ltd.) in an environment of 23°C and 50% RH, by depositing a drop of distilled water (liquid volume 4 μL) as the measurement liquid on the film surface S1 of the LCP extruded film 100, and measuring the contact angle 3 seconds after the drop has been deposited.

[0050] As mentioned above, in the LCP extrusion film of the prior art, the thermoplastic liquid crystal polymer was highly molecular oriented on the film surface S1, such as peeling of the skin layer or peeling of the fibrillated fibers on the film surface S1. It is presumed that this is because the thermoplastic liquid crystal polymer is highly oriented on the surface of the extrusion molded body due to shear stress from the side of the device during extrusion. It was confirmed that the extreme molecular orientation of the thermoplastic liquid crystal polymer on the film surface S1 was alleviated by the improvement as in Patent Document 1, but at the same time, the inventors found that it was not possible to realize a material that can withstand the required performance as an insulating material for circuit boards by only controlling the molecular orientation of the thermoplastic liquid crystal polymer on the film surface S1. In the technology of Patent Document 1, the difference in the dimensional change rate in the TD direction and the MD direction after etching was still large, and it was not possible to meet the recent demand for application to ultra-fine processing. In other words, in order to realize an LCP extrusion film with reduced anisotropy of the dimensional change rate, it is necessary not only to control the molecular orientation of the thermoplastic liquid crystal polymer on the film surface S1, but also to control the molecular orientation of the thermoplastic liquid crystal polymer occurring inside the film and reduce internal strain.

[0051] Therefore, in a preferred embodiment of the LCP extruded film 100 of the present embodiment, unlike the conventional technology, the molecular orientation and internal strain of the thermoplastic liquid crystal polymer are relaxed not only on the film surface S1 but also inside the film, and as a result, the anisotropy of the dimensional change rate is significantly reduced compared to the conventional technology. That is, in a preferred embodiment of the LCP extruded film 100 of the present embodiment, the hardness H1 at a depth of 1 μm located 1 μm in the thickness direction from the film surface S1 and the hardness H2 at the thickness center point, measured by the nanoindentation method on the film cross section parallel to the MD direction, satisfy -10.0≦100×(H2-H1) / H1≦0.0, and the linear expansion coefficients in the MD and TD directions at 23 to 200° C. measured by the TMA method in accordance with JIS K7197 are within the range of -30 to 55 ppm / K.

[0052] In a preferred embodiment of the LCP extrusion film 100 of this embodiment, in order to alleviate the molecular orientation and internal distortion of the thermoplastic liquid crystal polymer not only on the film surface S1 but also inside the film and reduce the anisotropy of the desired dimensional change rate, the hardness H1 at a depth of 1 μm located 1 μm in the thickness direction from the film surface S1 and the hardness H2 at the center point of the thickness, measured by nanoindentation method on a film cross section parallel to the MD direction, are adjusted to satisfy the relationship shown below. Preferably, −10.0≦100×(H2−H1) / H1≦0.0. More preferably, −7.5≦100×(H2−H1) / H1≦0.0. More preferably, −5.0≦100×(H2−H1) / H1≦0.0. The relationship represented by the above formula, i.e., the relationship between the hardness H1 at a depth of 1 μm and the hardness H2 at the center point of the thickness, indicates the orientation of the thermoplastic liquid crystal polymer in the film, and the lower the absolute value, the more isotropic the orientation in the MD and TD directions is.

[0053] Here, the hardness H1 at a depth of 1 μm located 1 μm from the film surface S1 in the thickness direction in the film cross section parallel to the MD direction (a position 1 μm from one film surface S1 in the thickness direction in the plan view of the film cross section) is an index indicating the molecular orientation and internal strain of the thermoplastic liquid crystal polymer in the vicinity of the film surface S1 of the LCP extruded film 100. The hardness H1 at a depth of 1 μm tends to be larger as the orientation of the thermoplastic liquid crystal polymer is lower, and tends to be smaller as the orientation of the thermoplastic liquid crystal polymer is higher. The hardness H1 at a depth of 1 μm is preferably 0.250 GPa or more, more preferably 0.255 GPa or more. On the other hand, the hardness H2 at the thickness center point in the film cross section parallel to the MD direction (a position equidistant from one film surface S1 and the other film surface in the plan view of the film cross section) is an index indicating the molecular orientation and internal strain of the thermoplastic liquid crystal polymer in the film interior of the LCP extruded film 100. The hardness H2 at the thickness center point tends to be larger as the orientation of the thermoplastic liquid crystal polymer is lower, and tends to be smaller as the orientation of the thermoplastic liquid crystal polymer is higher. The hardness H2 at the thickness center point is preferably 0.240 GPa or more, more preferably 0.245 GPa or more. The method for producing the film cross section parallel to the MD direction of the LCP extruded film 100 is not particularly limited, but from the viewpoint of ensuring the objectivity between the measurement data, the LCP extruded film 100 is processed by ion beam under freezing conditions to produce a film smooth cross section parallel to the MD direction.

[0054] In this specification, the hardness measurement by the nanoindentation method is performed by using a diamond Berkovich type indenter with an indentation depth hmax=0.05 μm to measure the hardness H1 at a point 1 μm from the film surface S1 and the hardness H2 at the thickness center point on the film cross section parallel to the MD direction of the LCP extruded film 100. As shown in Figure 2, the hardness H1 and hardness H2 are calculated from the following formula based on the maximum load Pmax and the contact projected area A (the area where the indenter contacts the film cross section). Hardness (GPa) = Pmax / A

[0055] On the other hand, in a preferred embodiment of the LCP extrusion film 100 of the present embodiment, not only the molecular orientation of the thermoplastic liquid crystal polymer represented by the above-mentioned degree of orientation, but also the molecular orientation of the thermoplastic liquid crystal polymer represented by the linear expansion coefficient in the MD direction and the TD direction is sufficiently reduced. As mentioned above, the LCP extrusion film described in Patent Document 1 of the prior art is protected by the thermoplastic resin layers of both outer layers during three-layer coextrusion, which slightly relaxes the molecular orientation of the thermoplastic liquid crystal polymer, thereby relaxing the anisotropy of the strength in the MD direction and the TD direction of the obtained thermoplastic liquid crystal polymer film. However, in reality, the LCP extrusion film described in Patent Document 1 has a stable linear expansion coefficient in the MD direction of about -20 ppm / K, while the linear expansion coefficient in the TD direction exceeds 55 ppm, and sometimes reaches about 100 ppm / K. As is clear from this, it is easily understood that the molecular orientation of the thermoplastic liquid crystal polymer still remains large in the LCP extrusion film described in Patent Document 1 of the prior art, or that internal distortion remains large in the entire film. Therefore, the molecular orientation and internal strain of the thermoplastic liquid crystal polymer in the entire LCP extruded film 100 must be controlled by a combination of the hardness measured by the nanoindentation method and the linear expansion coefficient.

[0056] In a preferred embodiment of the LCP extruded film 100 of the present embodiment, the linear expansion coefficients in the MD and TD directions (CTE, α2, 23 to 200°C) are in the range of -30 to 55 ppm / K. The LCP extruded film 100 having a linear expansion coefficient in this range is in a state in which internal strain and the like are sufficiently reduced, and can be an LCP extruded film with a small anisotropy of the dimensional change rate and a sufficiently small absolute value of the dimensional change rate compared to those not in this state. The linear expansion coefficient in the MD direction of the LCP extruded film 100 of the present embodiment (CTE, α2, 23 to 200°C) is preferably in the range of -30 to 40 ppm / K, more preferably in the range of -25 to 30 ppm / K, and even more preferably in the range of -20 to 20 ppm / K, from the viewpoint of improving adhesion to metal foil, etc. In a preferred embodiment of the LCP extruded film 100 of this embodiment, the coefficient of linear expansion in the TD direction (CTE, α2, 23 to 200°C) is preferably in the range of 0 to 55 ppm / K, more preferably in the range of 0 to 50 ppm / K, and even more preferably in the range of 0 to 45 ppm / K, from the viewpoint of improving adhesion to metal foil, etc.

[0057] In this specification, the linear expansion coefficient is measured by a TMA method according to JIS K7197, and the average linear expansion coefficient means the average value of the linear expansion coefficients at 23 to 200°C measured by the same method. The linear expansion coefficient measured here means the value when the LCP extruded film 100 is heated (1st heating) at a heating rate of 5°C / min, cooled (1st cooling) to the measurement environment temperature (23°C), and then heated a second time (2nd heating) at a heating rate of 5°C / min in order to see the value after removing the thermal history. Other detailed measurement conditions are in accordance with the conditions described in the examples described later.

[0058] In addition, in a preferred embodiment of the LCP extrusion film 100 of this embodiment, from the viewpoint of alleviating the molecular orientation and internal distortion of the thermoplastic liquid crystal polymer not only on the film surface S1 but also inside the film and reducing the desired anisotropy of the dimensional change rate, it is desirable that the orientation degree α1 including the exposed film surface S1 and the orientation degree α2 including the film surface S2 located at a depth of 5 μm from the film surface S1 and exposed by etching the film surface S1 in the thickness direction satisfy the relationship shown below. Preferably, −4.0≦[(α2−α1) / α1]×100≦0.0. More preferably, −3.0≦[(α2−α1) / α1]×100≦0.0. More preferably, −2.0≦[(α2−α1) / α1]×100≦0.0.

[0059] Here, as shown in FIG. 3, the film surface S1 is the outermost surface of the LCP extruded film 100 of this embodiment, and is an exposed surface exposed toward the outside. The orientation degree (orientation degree α1) including the film surface S1 is preferably 39.0% or less, more preferably 38.5% or less, and even more preferably 38.0% or less. On the other hand, the film surface S2 is a surface newly exposed by etching the film surface S1 of the LCP extruded film 100 of this embodiment in the thickness direction, and is represented by a dashed line in FIG. 3 as a virtual surface located at a depth of 5 μm from the film surface S1. The orientation degree (orientation degree α2) including this film surface S2 is preferably 37.7% or less, more preferably 37.5% or less, and even more preferably 37.3% or less. In addition, the depth at which the film surface S2 is located does not need to be strictly 5 μm from the film surface S1, taking into account dissolution errors during etching, etc., and may be 5.0 μm or more from the film surface S1. The etching conditions for preparing the film surface S2 are not particularly limited, but should conform to the conditions described in the examples below in order to ensure objectivity between the measurement data.

[0060] In this specification, the orientation degrees α1, α2 (%) including the film surfaces S1, S2 of the LCP extruded film 100 refer to values ​​calculated from the following formula based on the area ratio of the orientation peak in the diffraction intensity distribution curve obtained by performing X-ray diffraction measurement by a transmission method using an X-ray diffraction device. In general, when the measurement target has a low orientation degree (%), a broad diffraction peak with a low peak intensity is observed in the X-ray diffraction measurement, so that a calculation method based on the half-width of the orientation peak cannot guarantee high measurement accuracy. Therefore, in this specification, the orientation degrees α1, α2 (%) including the film surfaces S1, S2 are calculated using a calculation method based on the area ratio of the orientation peak, rather than the half-width of the orientation peak. Specifically, as shown in FIG. 4 and Equation 1, the calculation method is based on the area proportion of the orientation peak, in which the peak intensity (orientation component) is measured by 2θ / θ scan, and the intensity in the azimuth direction from 0° to 360° is measured by β scan to obtain the intensity distribution in the azimuth direction (base intensity (isotropic component)). The orientation degree (%) is calculated as the percentage of the area occupied by the orientation component excluding the area of ​​the base isotropic component to the total area (area of ​​the orientation component + area of ​​the isotropic component).

[0061]

number

[0062] On the other hand, the dielectric properties of the LCP extruded film 100 of the present embodiment can be appropriately set according to the desired performance, and are not particularly limited. r (36GHz) is preferably 2.5 or more and 3.7 or less, more preferably 3.0 to 3.5. Similarly, the dielectric tangent tanδ(36GHz) is preferably 0.0010 or more and 0.0050 or less, more preferably 0.0010 or more and 0.0045 or less. In this specification, the relative dielectric constant ε r and the dielectric loss tangent tanδ are values ​​at 36 GHz measured by a cavity resonator vibration method in accordance with JIS K6471. Other detailed measurement conditions are in accordance with the conditions described in the examples described later.

[0063] (LCP extrusion film manufacturing method) The LCP extruded film 100 of this embodiment can be obtained by extruding a resin composition containing the above-mentioned thermoplastic liquid crystal polymer and optional components such as inorganic fillers and other resin components as necessary to a predetermined thickness. The extrusion method can be any known method, and the type is not particularly limited. For example, the T-die method or the inflation method; for example, the multi-manifold coextrusion method or the feed block coextrusion method; for example, the multi-layer coextrusion method such as the two-layer coextrusion method or the three-layer coextrusion method; can be applied in any combination.

[0064] In particular, from the viewpoint of ease of control of the molecular orientation of the thermoplastic liquid crystal polymer on the film surface (film surface S1) and inside the film (film surface S2), a preferred embodiment is a method in which the above-mentioned resin composition is extruded from a T-die by an extrusion molding method using a T-die (hereinafter, sometimes simply referred to as a "T-die extrusion method") to form a film, and then, as necessary, a cooling treatment, a pressure bonding treatment, a pressurized heating treatment, etc. are performed to obtain a predetermined LCP extrusion film 100. Specifically, a resin composition A for the first outer layer containing a thermoplastic resin, a resin composition B for the intermediate layer containing a thermoplastic liquid crystal polymer, and a resin composition C for the second outer layer containing a thermoplastic resin are each prepared, and these are co-extruded from the co-extrusion die of the extruder to extrude a three-layered coextrusion melt, and the LCP extrusion film 100 is formed as a thermoplastic liquid crystal polymer layer of the intermediate layer. According to such co-extrusion molding, the molecular orientation of the thermoplastic liquid crystal polymer in the thermoplastic liquid crystal polymer layer of the intermediate layer is relaxed by being protected by the thermoplastic resin layers of both outer layers.

[0065] 5 to 7 are diagrams showing a preferred embodiment of the manufacturing method of the LCP extrusion film 100 of the present embodiment described above. Here, the above-mentioned resin composition B containing the above-mentioned thermoplastic liquid crystal polymer and optional components such as inorganic filler and other resin components as necessary is melt-extruded into a film shape from a T-die of an extruder. At this time, resin compositions A and C containing a thermoplastic resin are co-extruded on both sides of the above-mentioned film-shaped melt extrusion product to produce a co-extrusion melt (three-layer laminated film) of a predetermined thickness having a first outer layer (peeling layer) containing a thermoplastic resin, an intermediate layer (LCP layer) containing a thermoplastic liquid crystal polymer, and a second outer layer (peeling layer) containing a thermoplastic resin. This co-extrusion melt is drawn out by a take-up roll and sent to a cooling roll and a pressure-bonding roll. Thereafter, the first outer layer and the second outer layer are peeled off from the intermediate layer, and the thermoplastic resin layers of both outer layers and the thermoplastic liquid crystal polymer layer of the intermediate layer (LCP extrusion film 100) are wound up on a take-up roll, respectively.

[0066] The preparation of the resin composition B containing the thermoplastic liquid crystal polymer may be carried out according to a conventional method, and is not particularly limited. The above-mentioned components can be manufactured and processed by known methods such as kneading, melt kneading, granulation, extrusion molding, pressing or injection molding. When melt kneading, kneading devices such as commonly used single-screw or twin-screw extruders and various kneaders can be used. When supplying each component to these melt kneading devices, the liquid crystal polymer, other resin components, inorganic fillers, additives, etc. may be dry-blended in advance using a mixing device such as a tumbler or Henschel mixer. When melt kneading, the cylinder setting temperature of the kneading device may be appropriately set and is not particularly limited, but is generally preferably in the range of from the melting point of the liquid crystal polymer to 360 ° C., and more preferably from the melting point of the liquid crystal polymer + 10 ° C. to 360 ° C.

[0067] The resin compositions A and C containing a thermoplastic resin may be prepared according to a conventional method, and are not particularly limited. The thermoplastic resin used here is preferably one or more polar resins selected from the group consisting of (meth)acrylic resins such as PMMA, polyamide resins, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polycarbonate (PC), polyether ether ketone (PEEK), and polyphenyl sulfide (PPS). When the coextrusion melt is formed, polar resins such as polycarbonate and non-polar resins such as polymethylpentene effectively function as a release layer, but by using the preferred polar resins exemplified above, the above-mentioned contact angles σ1 and σ7, and attenuation rate ((σ7-σ1) / σ1) can be easily and reproducibly achieved. In addition, the resin compositions A and C may be blended with optional components such as other resin components and inorganic fillers that may be contained in the above-mentioned LCP extruded film 100 in addition to these thermoplastic resins. In addition, the resin composition A and the resin composition C may have the same resin composition or different resin compositions, and may contain the same thermoplastic resin or different thermoplastic resins. The resin compositions A and C containing thermoplastic resins can be manufactured and processed by known methods such as kneading, melt kneading, granulation, extrusion molding, pressing or injection molding. When melt kneading, kneading devices such as commonly used single-screw or twin-screw extruders and various kneaders can be used. When supplying each component to these melt kneading devices, the thermoplastic resin, other resin components, inorganic fillers, additives, etc. may be dry blended in advance using a mixing device such as a tumbler or Henschel mixer. During melt kneading, the cylinder setting temperature of the kneading device may be appropriately set below a temperature at which the thermoplastic resin does not deteriorate due to thermal decomposition, but is not particularly limited, and is generally preferably above the melting point of the thermoplastic resin, and more preferably above the melting point of the thermoplastic resin + 10 ° C. The contents of other resin components and additives in resin compositions A and C are not particularly limited, but from the viewpoints of molding processability, thermal stability, etc., they are preferably 0.01 to 10 mass% each, more preferably 0.1 to 7 mass% each, and even more preferably 0.5 to 5 mass% each, relative to the total amount of the LCP extruded film 100.

[0068] The conditions for co-extrusion are not particularly limited and may be appropriately set depending on the type and composition of the resin composition used, the desired performance of the target extruded film, etc. For example, the set temperature of the cylinder of the extruder is not particularly limited and may be appropriately set depending on the type and composition of the resin composition used, the desired performance of the target extruded film, etc., but is preferably 230 to 360°C, more preferably 280 to 350°C.

[0069] Similarly, the die width (mm) of the T-die may be appropriately set depending on the type and composition of the resin composition used, the desired performance of the target extruded film, etc., and is not particularly limited, but is generally preferably 200 to 2000 mm, and more preferably 400 to 1500 mm.

[0070] Furthermore, for example, the lip opening (mm) of the T-die may be set appropriately depending on the type and composition of the resin composition used, the desired performance of the target extruded film, etc., and is not particularly limited, but is generally preferably 0.1 to 3.0 (mm), and more preferably 0.2 to 2.0 (mm).

[0071] For example, the shear rate (sec -1 Similarly, the extrusion speed may be appropriately set depending on the type and composition of the resin composition used, the desired performance of the target extruded film, etc., and is not particularly limited, but is generally 100 to 1500 (sec -1 ), and more preferably 150 to 1000 (sec -1 ).

[0072] In addition, the total discharge amount of the resin composition from the T-die (mm 3 Similarly, the extrusion speed may be appropriately set depending on the type and composition of the resin composition used, the desired performance of the target extruded film, etc., and is not particularly limited, but is generally 500 to 15,000 (mm 3 / sec), and more preferably 1500 to 10000 (mm 3 / sec).

[0073] On the other hand, the melt viscosity (Pa·sec) of the thermoplastic liquid crystal polymer may also be appropriately set according to the type and composition of the resin composition used, the desired performance of the target extruded film, etc., and is not particularly limited, but is generally preferably 10 to 300 (Pa·sec), more preferably 20 to 250 (Pa·sec). The melt viscosity (Pa·sec) of the thermoplastic liquid crystal polymer means a value measured in accordance with JIS K7199 using a Capilograph 1D (manufactured by Toyo Seiki Seisakusho Co., Ltd.) under the conditions of a cylinder length of 10.00 mm, a cylinder diameter of 1.00 mm, and a barrel diameter of 9.55 mm under the conditions during the production of the LCP extruded film 100 (die temperature and shear rate of the lip wall).

[0074] Similarly, the take-up speed (mm / sec) of the co-extruded film may be appropriately set depending on the type and composition of the resin composition used, the desired performance of the target extruded film, etc., and is not particularly limited, but is generally preferably 15 to 1000 (mm / sec), and more preferably 20 to 500 (mm / sec).

[0075] Here, from the viewpoint of reducing the molecular orientation of the thermoplastic liquid crystal polymer in the MD direction during coextrusion, it is desirable that the shear stress (kPa) during coextrusion is low. If the shear stress during coextrusion is large, the thermoplastic liquid crystal polymer is likely to be highly oriented in the MD direction and internal strain is likely to remain, while if the shear stress during coextrusion is small, the molecular orientation of the thermoplastic liquid crystal polymer is likely to be reduced both on the film surface S1 and inside the film and internal strain is unlikely to remain. The shear stress (kPa) during coextrusion is determined by the shear rate (sec) of the lip wall. -1) and the melt viscosity (Pa·sec) of the thermoplastic liquid crystal polymer, and the shear rate is a value calculated based on the total discharge amount of the resin composition during co-extrusion, the die width, and the lip opening. Therefore, the shear stress during co-extrusion can be controlled by adjusting each of these values. Specifically, the shear stress during co-extrusion is preferably 40 kPa or less, more preferably 38 kPa or less, and even more preferably 36 kPa or less. The lower limit is not particularly limited, but is preferably 5 kPa or more, more preferably 10 kPa or more, in consideration of productivity, etc.

[0076] In addition, from the viewpoint of reducing the molecular orientation of the thermoplastic liquid crystal polymer in the MD direction during coextrusion, it is desirable that the drawdown ratio during coextrusion is low. If the drawdown ratio during coextrusion is large, the thermoplastic liquid crystal polymer is likely to be highly oriented in the MD direction and internal strain is likely to remain, and if the drawdown ratio during coextrusion is small, the molecular orientation of the thermoplastic liquid crystal polymer is likely to be reduced both on the film surface S1 and inside the film, and internal strain is unlikely to remain. The drawdown ratio is a value expressed by the take-up speed (mm / sec) / flow rate of the thermoplastic liquid crystal polymer (mm / sec), and the flow rate of the thermoplastic liquid crystal polymer is a value calculated based on the total discharge amount of the resin composition during coextrusion, the die width, and the lip opening. Therefore, the drawdown ratio during coextrusion can be controlled by adjusting each of these values. Specifically, the drawdown ratio during coextrusion is preferably 3.5 or less, more preferably 3.3 or less, and even more preferably 3.1 or less. The lower limit is not particularly limited, but is preferably 1.0 or more, more preferably 1.2 or more, taking into consideration productivity and the like.

[0077] The thickness of the resulting LCP extruded film 100 can be appropriately set according to requirements and is not particularly limited. In consideration of handleability and productivity during extrusion molding, the thickness is preferably 15 μm to 300 μm, more preferably 18 μm to 250 μm, and even more preferably 20 μm to 200 μm.

[0078] The melting point (melting temperature) of the obtained LCP extruded film 100 is not particularly limited, but from the viewpoint of the heat resistance and processability of the film, the melting point (melting temperature) is preferably 200 to 400° C., and from the viewpoint of improving the thermocompression bonding to metal foil in particular, the melting point (melting temperature) is preferably 250 to 360° C., more preferably 260 to 355° C., even more preferably 270 to 350° C., and particularly preferably 275 to 345° C. In this specification, the melting point of the LCP extruded film 100 means the melting peak temperature in differential scanning calorimetry (DSC) when the extruded film is heated (1st heating) at a temperature rise rate of 20° C. / min in the temperature range of 30 to 400° C. using DSC8500 (manufactured by PerkinElmer) to see the value after eliminating the thermal history, and then cooled (1st cooling) at a temperature drop rate of 50° C. / min, and then heated a second time (2nd heating) at a temperature rise rate of 20° C. / min. Other conditions should be in accordance with the measurement conditions described in the Examples section below.

[0079] The extrusion-molded LCP extrusion film 100 can be used as is, but if necessary, a pressure and heating process can be carried out to further reduce the orientation (anisotropy) or further release the internal strain, thereby realizing an LCP extrusion film 100 with reduced anisotropy in the dimensional change rate or an LCP extrusion film 100 with a smaller absolute value of the dimensional change rate.

[0080] The heat and pressure treatment may be performed by a method known in the art, such as a contact heat treatment or a non-contact heat treatment, and the type is not particularly limited. For example, heat setting may be performed using known equipment such as a non-contact heater, an oven, a blowing device, a heat roll, a cooling roll, a heat press, or a double-belt heat press. At this time, if necessary, a release film or a porous film known in the art may be arranged on the surface of the LCP extruded film 100, and the heat treatment may be performed. In addition, when performing this heat treatment, from the viewpoint of controlling the orientation, a heat and pressure molding method is preferably used in which a release film or a porous film is arranged on the front and back of the LCP extruded film 100, and the film is thermocompressed while being sandwiched between a pair of endless belts of a double-belt press, and then the release film or the porous film is removed. The heat and pressure molding method may be performed by referring to, for example, JP-A-2010-221694. The processing temperature when the LCP extrusion film 100 using the above resin composition is thermocompressed between the pair of endless belts of a double belt press is preferably higher than the melting point of the liquid crystal polymer and lower than 70°C higher than the melting point, more preferably higher than +5°C higher than the melting point and lower than 60°C higher than the melting point, and even more preferably higher than +10°C higher than the melting point and lower than 50°C higher than the melting point. The thermocompression bonding conditions can be appropriately set according to the desired performance, and are not particularly limited, but are preferably performed under conditions of a surface pressure of 0.5 to 10 MPa and a heating temperature of 250 to 430°C, more preferably under conditions of a surface pressure of 0.6 to 8 MPa and a heating temperature of 260 to 400°C, and even more preferably under conditions of a surface pressure of 0.7 to 6 MPa and a heating temperature of 270 to 370°C. On the other hand, when a non-contact heater or oven is used, it is preferably performed under conditions of, for example, 200 to 320°C for 1 to 20 hours.

[0081] (Insulating materials for circuit boards) 8 is a schematic cross-sectional view showing a main portion of an insulating material for circuit boards 200 of this embodiment. The insulating material for circuit boards 200 of this embodiment comprises a laminate having at least the above-mentioned LCP extruded film 100 and a woven fabric WF provided on one side and / or both sides of the LCP extruded film 100.

[0082] Specifically, the insulating material 200 for circuit boards includes a laminate having a layered structure (three-layer structure) in which an LCP extruded film 100, a woven fabric WF, and an LCP extruded film 100 are arranged at least in this order. In this laminate, one LCP extruded film 100 is provided on the front side of the woven fabric WF, and the other LCP extruded film 100 is provided on the back side of the woven fabric WF. These three layers are thermally pressed together to form a three-layer laminate. Note that although a three-layer laminate is illustrated here, it goes without saying that the present invention can also be implemented with a two-layer laminate in which one LCP extruded film 100 is omitted, or with a four-layer or more laminate in which the LCP extruded film 100 and the woven fabric WF are further laminated.

[0083] In this specification, "a woven fabric WF is provided on one and / or both sides of the LCP extruded film 100" refers not only to an embodiment in which the LCP extruded film 100 is directly placed on the surface of the woven fabric WF as in this embodiment, but also to an embodiment in which the LCP extruded film 100 is positioned at a distance from the woven fabric WF with any layer (e.g., a primer layer, an adhesive layer, etc.) not shown in the figure being interposed between the LCP extruded film 100 and the woven fabric WF.

[0084] The woven fabric WF is a cloth made of woven fibers. The type of fiber of the woven fabric WF is not particularly limited, and any of inorganic fibers, organic fibers, and organic-inorganic hybrid fibers can be used. In particular, the woven fabric WF of inorganic fibers is preferably used. By thermocompression bonding the woven fabric WF of inorganic fibers to the LCP extruded film 100, the anisotropy of the dimensional change rate in the MD and TD directions can be kept small, and in a more preferred embodiment, the dimensional change rate in the MD and TD directions themselves can be reduced. As the woven fabric WF, a commercially available product can be used, and it can be produced by a method known in the art.

[0085] Examples of inorganic fibers include glass fibers such as E glass, D glass, L glass, M glass, S glass, T glass, Q glass, UN glass, NE glass, and spherical glass, inorganic fibers other than glass such as quartz, and ceramic fibers such as silica, but are not particularly limited thereto. As the woven fabric WF of inorganic fibers, a woven fabric subjected to a fiber-opening treatment or a clogging treatment is preferable from the viewpoint of dimensional stability. Among these, glass cloth is preferable from the viewpoint of mechanical strength, dimensional stability, water absorption, and the like. From the viewpoint of enhancing the thermocompression bonding with the LCP extruded film 100, glass cloth subjected to a fiber-opening treatment or a clogging treatment is preferable. In addition, glass cloth surface-treated with a silane coupling agent such as epoxy silane treatment or amino silane treatment can also be preferably used. The woven fabric WF can be used alone or in appropriate combination of two or more types.

[0086] The thickness of the woven fabric WF is not particularly limited and can be appropriately set depending on the required performance. From the viewpoints of lamination property, processability, mechanical strength, etc., the thickness is preferably 10 to 300 μm, more preferably 10 to 200 μm, and further preferably 15 to 180 μm.

[0087] The total thickness of the insulating material 200 for circuit boards is not particularly limited and can be appropriately set depending on the required performance. From the viewpoints of lamination property, processability, mechanical strength, etc., it is preferably 30 to 500 μm, more preferably 50 to 400 μm, further preferably 70 to 300 μm, and particularly preferably 90 to 250 μm.

[0088] By adopting the preferred configuration described above, the insulating material 200 for circuit boards of this embodiment has small anisotropy in the dimensional change rate in the MD and TD directions, and in a more preferred embodiment, the dimensional change rates in the MD and TD directions themselves can be made small. Moreover, it has the remarkable effects of having excellent dielectric properties in the high frequency range, being easy to manufacture, and having excellent productivity.

[0089] The above-mentioned insulating material 200 for circuit boards can be manufactured by appropriately applying a known manufacturing method, and the manufacturing method is not particularly limited. For example, the insulating material 200 for circuit boards can be obtained by laminating the LCP extruded film 100 and the woven fabric WF, heating and pressing the LCP extruded film 100 and the woven fabric WF, and thermocompression bonding the LCP extruded film 100 and the woven fabric WF. In addition, a method is also preferred in which the LCP extruded film 100, the woven fabric WF, and the LCP extruded film 100 are laminated in this order to form a laminate, and the laminate is sandwiched and heated and pressed using a press machine, a double belt press machine, or the like to thermocompress the insulating material 200 for circuit boards. The processing temperature during thermocompression bonding can be appropriately set according to the required performance, and is not particularly limited, but is preferably 200 to 400°C, more preferably 250 to 360°C, and even more preferably 270 to 350°C. The processing temperature during thermocompression bonding is a value measured at the surface temperature of the LCP extruded film 100 of the above-mentioned laminate. The pressure conditions can be appropriately set depending on the desired performance and are not particularly limited, but are, for example, a surface pressure of 0.5 to 10 MPa for 1 to 240 minutes, more preferably a surface pressure of 0.8 to 8 MPa for 1 to 120 minutes.

[0090] (Metal foil laminate) 9 is a schematic cross-sectional view showing a main portion of a metal foil-clad laminate 300 of this embodiment. The metal foil-clad laminate 300 of this embodiment includes the above-mentioned LCP extruded film 100 and a metal foil MF provided on one side and / or both sides of the LCP extruded film 100.

[0091] Specifically, the metal foil-clad laminate 300 is a double-sided metal foil-clad laminate having a laminated structure (three-layer structure) in which the metal foil MF, the LCP extruded film 100, and the metal foil MF are arranged at least in this order. These three layers are heat-pressed to form a three-layer laminate. In this embodiment, a double-sided metal foil-clad laminate is shown, but the present invention can also be implemented in an embodiment in which the metal foil MF is provided only on one surface of the LCP extruded film 100. That is, although a three-layer laminate is exemplified here, it goes without saying that the present invention can also be implemented in a two-layer laminate in which one of the metal foil MFs is omitted, or in a four-layer or more laminate structure in which the LCP extruded film 100 or the woven fabric WF is further laminated.

[0092] 10 is a schematic cross-sectional view showing a main portion of a metal foil-clad laminate 400 of this embodiment. The metal foil-clad laminate 400 of this embodiment comprises the above-mentioned LCP extruded film 100 and a laminate having at least the above-mentioned woven fabric WF provided on one and / or both sides of this LCP extruded film 100, and a metal foil MF provided on one and / or both sides of this laminate.

[0093] Specifically, the metal foil-clad laminate 400 is a double-sided metal foil-clad laminate having a laminated structure (five-layer structure) in which the metal foil MF, the LCP extruded film 100, the woven fabric WF, the LCP extruded film 100, and the metal foil MF are arranged at least in this order. These five layers are heat-pressed to form a five-layer laminate. In this embodiment, a double-sided metal foil-clad laminate is shown, but the present invention can also be implemented in an embodiment in which the metal foil MF is provided only on one surface. That is, although a five-layer laminate is exemplified here, it goes without saying that the present invention can also be implemented in a four-layer laminate in which one of the metal foils MF is omitted, or in a six-layer or more laminate structure in which the LCP extruded film 100, the insulating material 200 for circuit boards, and the woven fabric WF are further laminated.

[0094] The material of the metal foil MF is not particularly limited, but includes gold, silver, copper, copper alloy, nickel, nickel alloy, aluminum, aluminum alloy, iron, iron alloy, etc. Among these, copper foil, aluminum foil, stainless steel foil, and copper-aluminum alloy foil are preferred, and copper foil is more preferred. As such copper foil, any foil manufactured by rolling method or electrolysis method can be used, but electrolytic copper foil and rolled copper foil, which have a relatively large surface roughness, are preferred.

[0095] The thickness of the metal foil MF can be appropriately set according to the desired performance, and is not particularly limited. Usually, it is preferably 1.5 to 1000 μm, more preferably 2 to 500 μm, further preferably 5 to 150 μm, and particularly preferably 7 to 100 μm. In addition, the metal foil MF may be subjected to a surface treatment such as a chemical surface treatment such as acid washing, as long as the effect of the present invention is not impaired. In addition, the type and thickness of the metal foil MF may be the same or different.

[0096] The method of providing the metal foil MF on the surface of the LCP extrusion film 100 or the insulating material for circuit boards 200 can be performed according to a conventional method and is not particularly limited. Any of the following methods may be used: a method of laminating the metal foil MF on the LCP extrusion film 100 or the insulating material for circuit boards 200 and adhering or pressing the two layers together; a physical method (dry method) such as sputtering or vapor deposition; a chemical method (wet method) such as electroless plating or electrolytic plating after electroless plating; or a method of applying a metal paste. In addition, the metal foil-clad laminate 300, 400 can also be obtained by hot pressing the laminate obtained by laminating the LCP extrusion film 100 or the insulating material for circuit boards 200 and one or more metal foils MF using, for example, a multi-stage press machine, a multi-stage vacuum press machine, a continuous molding machine, an autoclave molding machine, or the like.

[0097] The above-mentioned metal foil-clad laminate 300, 400 can be manufactured by appropriately applying a known manufacturing method, and the manufacturing method is not particularly limited. For example, the LCP extruded film 100 or the insulating material for circuit board 200 is laminated with the metal foil MF to form a laminate in which the metal foil MF is placed on the LCP extruded film 100, and the laminate is thermocompressed while being sandwiched between a pair of endless belts of a double belt press. As described above, the LCP extruded film 100 used in this embodiment has high adhesion to the metal foil and high metal foil peel strength. In addition, the anisotropy of the dimensional change rate in the MD direction and the TD direction is small, and in a more preferred embodiment, the dimensional change rate in the MD direction and the TD direction itself is small, so that high peel strength to the metal foil MF can be obtained.

[0098] The temperature during thermocompression bonding of the metal foil MF can be appropriately set according to the required performance, and is not particularly limited, but is preferably 50°C lower than the melting point of the liquid crystal polymer and 50°C higher than the melting point, more preferably 40°C lower than the melting point and 40°C higher than the melting point, more preferably 30°C lower than the melting point and 30°C higher than the melting point, and particularly preferably 20°C lower than the melting point and 20°C higher than the melting point. The temperature during thermocompression bonding of the metal foil MF is the value measured at the surface temperature of the LCP extruded film 100 described above. The pressure bonding conditions at this time can be appropriately set according to the desired performance, and are not particularly limited, but for example, when using a double belt press machine, it is preferable to perform the bonding under conditions of a surface pressure of 0.5 to 10 MPa and a heating temperature of 200 to 360°C.

[0099] The metal foil-clad laminate 300, 400 of this embodiment may have another or further laminate structure as long as it has a two-layer structure of the LCP extrusion film 100 and the metal foil MF. For example, it may have a two-layer structure of metal foil MF / LCP extrusion film 100; a three-layer structure such as metal foil MF / LCP extrusion film 100 / metal foil MF, or LCP extrusion film 100 / metal foil MF / LCP extrusion film 100; a four-layer structure such as metal foil MF / LCP extrusion film 100 / woven fabric WF / LCP extrusion film 100; a five-layer structure such as metal foil MF / LCP extrusion film 100 / metal foil MF / LCP extrusion film 100 / metal foil MF, or metal foil MF / LCP extrusion film 100 / woven fabric WF / LCP extrusion film 100 / metal foil MF; etc. It is also possible to laminate and heat-press multiple (for example, 2 to 50) metal foil-clad laminates 300, 400.

[0100] In the metal foil-clad laminate 300, 400 of this embodiment, the peel strength between the LCP extrusion film 100 and the metal foil MF is not particularly limited, but from the viewpoint of providing a higher peel strength, it is preferably 0.8 (N / mm) or more, more preferably 1.0 (N / mm) or more, and even more preferably 1.2 (N / mm) or more. As described above, the metal foil-clad laminate 300, 400 of this embodiment can realize a high peel strength, so that peeling between the LCP extrusion film 100 and the metal foil MF can be suppressed, for example, during the heating process of substrate manufacturing. In addition, since manufacturing conditions with excellent process tolerance and productivity can be applied to obtain a peel strength equivalent to that of the conventional technology, deterioration of the basic performance of the liquid crystal polymer can be suppressed while maintaining the same level of peel strength as the conventional technology.

[0101] The metal foil-clad laminates 300, 400 of this embodiment can be used as materials for circuit boards such as electronic circuit boards and multilayer boards by pattern-etching at least a part of the metal foil MF, etc. The metal foil-clad laminates 300, 400 of this embodiment have excellent dielectric properties in the high frequency range, small anisotropy in the dimensional change rates in the MD and TD directions, and in a more preferred embodiment, small dimensional change rates in the MD and TD directions themselves, excellent dimensional stability, easy manufacturing, and excellent productivity, making them particularly useful materials as insulating materials for flexible printed circuit boards (FPCs) in fifth-generation mobile communication systems (5G), millimeter-wave radars, etc. EXAMPLES

[0102] The features of the present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto. That is, the materials, amounts used, ratios, processing contents, processing procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. In addition, the values ​​of various manufacturing conditions and evaluation results in the following examples are meant as preferred upper or lower limits in the embodiment of the present invention, and the preferred numerical range may be a range defined by a combination of the above-mentioned upper or lower limit and the values ​​of the following examples or the values ​​of the examples.

[0103] [Melt Viscosity] The melt viscosity [Pa·sec] of each LCP extruded film was measured under the following conditions. Measuring equipment: Capillograph 1D (manufactured by Toyo Seiki Co., Ltd.) Equipment used: Cylinder length 10.00mm, cylinder diameter 1.00mm, barrel diameter 9.55mm Measurement conditions: Temperature [℃] and shear rate [sec ] during extrusion of each LCP extrusion film -1 ]

[0104] [Contact angle and attenuation rate] The contact angle σ1 (after 1 day of constant temperature and humidity treatment at 23°C and 50% RH) and the contact angle σ7 (after 7 days of constant temperature and humidity treatment at 23°C and 50% RH) of the film surface S1 of the LCP extrusion film with water were measured using an automatic contact angle meter (DMC-MC3, manufactured by Kyowa Interface Science Co., Ltd.) under an environment of 23°C and 50% RH by depositing a drop of distilled water (liquid volume 4 μL) as a measurement liquid on the film surface S1 of the LCP extrusion film 100, and measuring the contact angle 3 seconds after the drop was deposited based on the tangent method. Based on the obtained measurement results, the attenuation rate of the contact angle σ7 relative to the contact angle σ1 ((σ7-σ1) / σ1) was calculated.

[0105] [Peel Strength] The copper foil peel strength of the flexible laminate was measured under the following conditions. Here, a 12 μm thick electrolytic copper foil (TQ-M7VSP manufactured by Mitsui Kinzoku Co., Ltd.) was laminated on one side of each LCP extrusion film stored for 7 days under an environment of 23 ° C and 50% RH, and the film was heat-pressed at a surface pressure of 5 MPa for 1 minute under a temperature condition of the melting point of the thermoplastic liquid crystal polymer film -10 ° C to produce a metal foil-clad laminate (flexible laminate) having a two-layer structure of an LCP extrusion film and a copper foil. A test piece having a width of 10 mm was cut into a rectangular shape from the obtained flexible laminate, and peeled in a 180-degree direction at a tensile speed of 50 mm / min using a Strograph VE1D (manufactured by Toyo Seiki Seisakusho Co., Ltd.) under an environment of 23 ° C and 50% RH at a temperature of 23 ° C and 50% RH, and the copper foil peel strength was measured and evaluated according to the following criteria. ○: Material breaks from 1.0N / mm or more ×: Less than 1.0N / mm

[0106] [Hardness measurement using nanoindentation method] Using the nanoindenter method in accordance with ISO 14577, the hardness H1 at a depth of 1 μm and the hardness H2 at the center of the thickness of each LCP extruded film stored for 7 days in an environment of 23°C and 50% RH were measured. Measurement equipment: Nanoindenter Hysitron TI 950 TriboIndenter (manufactured by Bruker) Indenter used: Diamond Berkovich type indenter Measurement conditions: Indentation depth hmax 0.05μm Measurement method Load-unload test The measurement surface of each LCP extruded film was a smooth cross section of the film parallel to the MD direction of each LCP extruded film, and such smooth cross sections were prepared by cutting each LCP extruded film using ion beam processing under freezing conditions.

[0107] [Linear expansion coefficient] The linear expansion coefficient of each LCP extruded film stored for 7 days in an environment of 23°C and 50% RH was measured using the TMA method in accordance with JIS K7197. Measuring equipment: TMA 4000SE (NETZSCH) Measurement method: Tensile mode Measurement conditions: Sample size 25mm x 4mm x thickness 50μm Chuck distance: 20mm Temperature range: 23~200℃ (2nd RUN) Heating rate: 5℃ / min Atmosphere: Nitrogen (flow rate 50ml / min) Test load: 5gf *The value from the 2nd run was used to see the value after eliminating the thermal history.

[0108] [Orientation degree] X-ray diffraction measurements were performed on each LCP extrusion film stored for 7 days under an environment of 23°C and 50% RH as follows. Using an X-ray diffraction device Smartlab (manufactured by Rigaku Corporation), X-ray diffraction measurements were performed on each LCP extrusion film including film surface S1 or film surface S2 by the transmission method, and the degree of orientation was measured. Here, a Cu sealed tube was used as the X-ray source, and X-ray diffraction measurements (2θ / θ scan, β scan) were performed by the parallel beam optical system and the transmission method, and first, it was confirmed that there was a peak top at 2θ=19.5° in the 2θ / θ scan. Next, the intensity distribution in the azimuth angle direction was obtained by measuring the intensity from 0° to 360° for the diffraction peak at 2θ=19.5 in the β scan. The degree of orientation was calculated from the base intensity (isotropic component) and peak intensity (orientation component) of the obtained β profile based on the area ratio of the orientation peak using the above formula. The film surface S2 of each LCP extruded film was adjusted by immersing each LCP extruded film in a 70% aqueous monoethylamine solution (manufactured by Daicel Corporation) for 168 hours in an environment of 23°C and 50% RH, etching both surfaces of each LCP extruded film to a depth of 5 μm, washing with running water for 5 minutes, washing with distilled water, drying at 80°C for 1 hour, and cooling in an environment of 23°C and 50% RH for 24 hours.

[0109] [Tape peeling test] The film surface S1 of each LCP extrusion film stored for 7 days in an environment of 23°C and 50% RH was subjected to an adhesion test by the cross-cut method according to JIS K5600-5-6 to confirm the presence or absence of a skin layer. At this time, Nichiban Co., Ltd.'s Cellotape (registered trademark) with a width of 24 mm and a length of 50 mm was used, and when the tape was peeled off and there was no peeling in the grid, it was judged as "no skin layer", and when there was peeling, it was judged as "skin layer present". ○ No skin layer × Skin layer present

[0110] [Dimensional change rate and its anisotropy after metal foil etching] Each LCP extrusion film was stored for 7 days under an environment of 23°C and 50% RH, and a 12μm-thick electrolytic copper foil (TQ-M7VSP manufactured by Mitsui Kinzoku Co., Ltd.) was laminated on both sides of the film, and the film was heat-pressed at a temperature of 320°C and a surface pressure of 1MPa for 1 minute to produce a double-sided metal foil-clad laminate having a three-layer structure of copper foil / LCP extrusion film / copper foil. Then, in accordance with JPCA-UB01 (2017), samples were prepared from the obtained double-sided metal foil-clad laminate in accordance with "16.4.4-18 Dimensional change rate" and "16.4.4-2-2 Sample preparation by copper foil removal" of the same standard, and the dimensional change rate of each sample after copper foil etching was measured using a measuring microscope (MF-A4020C manufactured by Mitutoyo Corporation) to evaluate the anisotropy of the dimensional change rate. Here, β1 represents the dimensional change rate in the MD direction, and β2 represents the dimensional change rate in the TD direction. ◎ The anisotropy of the dimensional change rate is very small (|β2-β1|≦0.3%) ○ Small anisotropy of dimensional change rate (0.3%<|β2-β1|<0.4%) × The anisotropy of the dimensional change rate is large (0.4%≦|β2-β1|)

[0111] Example 1 The intermediate layer was a type II thermoplastic liquid crystal polymer (a copolymer of 74 mol% p-hydroxybenzoic acid and 26 mol% 6-hydroxy-2-naphthoic acid, at a temperature of 300°C and a shear rate of 500 sec -1 The melt viscosity of 80 Pa·sec) was used as the outer layer of the intermediate layer, and polycarbonate PC (301-15 manufactured by Sumika Polycarbonate Co., Ltd.) was used as the outer layer on both sides of the intermediate layer, and each resin was co-extruded at 300°C by a T-die casting method from a two-type three-layer extruder equipped with a T-die with a die width of 600 mm and a lip opening of 0.2 to 1.0 mm under the molding conditions shown in Table 1, to form a two-type three-layer film with an intermediate layer of 50 μm. The polycarbonate films of both outer layers were peeled off from the molded two-type three-layer film on a winding line, respectively, to obtain an LCP extrusion film of Example 1 having a melting point of 280°C and a thickness of 50 μm. In addition, a glass cloth (IPC No. #1037) was sandwiched between the obtained pair of thermoplastic liquid crystal polymer films of Example 1, and a heat pressing treatment was performed for 5 minutes at 300°C using a heat press machine, to obtain an insulating material for circuit boards of Example 1 having a melting point of 280°C and a total thickness of 100 μm.

[0112] Example 2 The same procedure as in Example 1 was repeated except that polybutylene terephthalate PBT (5010R3-2NA manufactured by Mitsubishi EP) was used instead of polycarbonate PC (301-15 manufactured by Sumika Polycarbonate Co., Ltd.) as the outer layers on both sides of the intermediate layer, to obtain an LCP extruded film of Example 2 having a melting point of 280°C and a thickness of 50 μm, and an insulating material for circuit boards of Example 2 having a melting point of 280°C and a total thickness of 100 μm.

[0113] Example 3 The same procedure as in Example 1 was repeated except that polyamide resin PA (M1040E-N manufactured by Unitika Ltd.) was used instead of polycarbonate PC (301-15 manufactured by Sumika Polycarbonate Co., Ltd.) as the outer layers on both sides of the intermediate layer, to obtain an LCP extruded film of Example 3 having a melting point of 280°C and a thickness of 50 μm, and an insulating material for circuit boards of Example 3 having a melting point of 280°C and a total thickness of 100 μm.

[0114] (Reference example 1) Type II thermoplastic liquid crystal polymer (a copolymer of 74 mol% p-hydroxybenzoic acid and 26 mol% 6-hydroxy-2-naphthoic acid, temperature 300°C and shear rate 500 sec -1 The liquid crystal polymer was extruded at 300°C by a T-die casting method from a single-layer extruder equipped with a T-die having a die width of 600 mm and a lip opening of 0.3 mm under the molding conditions shown in Table 1 using a melt viscosity of 80 Pa sec., to obtain an LCP extruded film of Reference Example 1 having a melting point of 280°C and a thickness of 50 μm, and an insulating material for circuit boards of Reference Example 1 having a melting point of 280°C and a total thickness of 100 μm.

[0115] (Reference example 2) The surface of the LCP extrusion film of Reference Example 1 was subjected to corona discharge treatment (Kasuga Electric Co., Ltd. TEC-4AX, treatment width 0 m × line speed 1.0 m / min, output 36 W, discharge amount 120 W min / m 2 ) was carried out to obtain an LCP extruded film of Reference Example 2 having a melting point of 280° C. and a thickness of 50 μm, and an insulating material for circuit boards of Reference Example 2 having a melting point of 280° C. and a total thickness of 100 μm.

[0116] Comparative Example 1 The same procedure as in Example 1 was carried out except that polymethylpentene PMP (TPX MX004 manufactured by Mitsui Chemicals, Inc.) was used instead of polycarbonate PC (301-15 manufactured by Sumika Polycarbonate Co., Ltd.) as the outer layers on both sides of the intermediate layer, and an LCP extruded film of Comparative Example 1 having a melting point of 280°C and a thickness of 50 μm and an insulating material for circuit boards of Comparative Example 1 having a melting point of 280°C and a total thickness of 100 μm were obtained.

[0117] Comparative Example 2 The same procedure as in Example 1 was carried out except that high density polyethylene HDPE (HF-313, manufactured by Mitsubishi Chemical Corporation) was used instead of polycarbonate PC (301-15, manufactured by Sumika Polycarbonate Co., Ltd.) as the outer layers on both sides of the intermediate layer, thereby obtaining an LCP extruded film of Comparative Example 2 having a melting point of 280°C and a thickness of 50 μm, and an insulating material for circuit boards of Comparative Example 2 having a melting point of 280°C and a total thickness of 100 μm.

[0118] [Table 1]

[0119] Tables 2 and 3 show the measurement results of various performances. [Table 2]

[0120] [Table 3]

[0121] [Table 4] [Industrial Applicability]

[0122] The extruded LCP film of the present invention can be widely and effectively used in applications such as electronic circuit boards, multilayer boards, high heat dissipation boards, flexible printed wiring boards, antenna boards, optoelectronic hybrid boards, and IC packages. In particular, since it is suitable for ultrafine processing and has high reliability, it can be widely and effectively used as an insulating material such as flexible printed wiring boards (FPCs) in fifth-generation mobile communication systems (5G) and millimeter-wave radars, as well as metal foil-clad laminates. [Explanation of symbols]

[0123] 100···LCP extrusion film 100a··· surface 100b...plane H1: Hardness at a depth of 1 μm H2: Hardness at the center of thickness S1 Film surface S2: Film surface at a depth of 5 μm 200 Insulating materials for circuit boards 300 Metal foil laminate 400 Metal foil laminate WF: Woven fabric MF Metal foil

Claims

1. An extruded LCP film comprising a thermoplastic liquid crystal polymer having a film surface S1, The LCP extruded film after one day of constant temperature and humidity treatment at 23° C. and 50% RH Contact angle σ of surface S1 with water 1 At a constant temperature of 23°C and 50% RH, The contact angle σ of the film surface S1 of the LCP extruded film with water after 7 days of temperature and humidity treatment 7 is 60° or more and 80° or less, and the contact angle σ 1 The contact angle σ 7 The decay rate of ( (σ 7 -σ 1 ) / σ 1 ) is 10.0% or less, LCP extruded film.

2. The linear expansion coefficient of the LCP extruded film in the MD direction and the TD direction is −30 to 55 ppm / Within the range of K The extruded LCP film of claim 1 .

3. A laminated extruded film having an outer layer, an intermediate layer, and an outer layer, the intermediate layer being removed from the outer layer. Layer 3. The extruded LCP film of claim 1 or 2.

4. The film surface S1 is not subjected to any physical surface treatment.

3. The extruded LCP film of claim 1 or 2.

5. The thickness is 15 μm or more and 300 μm or less, The film cross section parallel to the MD direction was measured using the nanoindentation method. The hardness H1 at a depth of 1 μm located 1 μm from the surface S1 in the thickness direction and the hardness at the center of the thickness H2 and H1 satisfy -10.0≦100×(H2−H1) / H1≦0.0, and The LCP at 23 to 200° C. measured by a TMA method according to K7197 The linear expansion coefficient of the extruded film in the MD and TD directions is within the range of -30 to 55 ppm / K. be 3. The extruded LCP film of claim 1 or 2.

6. The linear expansion coefficient in the TD direction of the LCP extruded film is 0 to 55 ppm / K. The extruded LCP film of claim 2.

7. The film surface S1 is cut by a cross-cut method according to JIS K5600-5-6. In an adhesion test using 3. The extruded LCP film of claim 1 or 2.

8. The hardness H2 at the thickness center point is 0.240 (GPa) or more. The extruded LCP film of claim 5.

9. The hardness H1 at the 1 μm depth point is 0.250 (GPa) or more. The extruded LCP film of claim 5.

10. Further containing inorganic filler 3. The extruded LCP film of claim 1 or 2.

11. T-die extrusion film 3. The extruded LCP film of claim 1 or 2.

12. The extruded LCP film according to claim 1 or 2 and at least one of the extruded LCP film A laminate having at least a woven fabric provided on one surface thereof, Insulating material for circuit boards.

13. The extruded LCP film according to claim 1 or 2 and one side and / or the extruded LCP film Or has metal foil on both sides, Metal foil laminate.

14. A laminate comprising at least the LCP extruded film and woven fabric according to claim 1 or 2, A metal foil is provided on one and / or both sides of the laminate. Metal foil laminate.

15. (Meth)acrylic resin, polyamide resin, polybutylene terephthalate, polyethylene terephthalate, polycarbonate, polyether ether ketone, and polyphenyl a resin for the first outer layer comprising one or more thermoplastic resins selected from the group consisting of sulfides; a resin composition for an intermediate layer comprising a thermoplastic liquid crystal polymer and a (meth)acrylic resin Fat, polyamide resin, polybutylene terephthalate, polyethylene terephthalate, poly The group consisting of carbonate, polyether ether ketone, and polyphenyl sulfide The resin composition for the second outer layer is co-extruded with the resin composition for the second outer layer, the resin composition comprising one or more thermoplastic resins selected from the following: A coextruded film having a laminated structure in which a first outer layer, an intermediate layer, and a second outer layer are arranged in this order. obtaining the above-mentioned The first outer layer and the second outer layer are removed from the coextruded film, and the thermoplastic liquid crystal polymer is The method comprises at least a step of obtaining the intermediate layer containing a polymer, In the step of obtaining the intermediate layer, an LCP extruded film having a film surface S1, The surface of the LCP extruded film after one day of constant temperature and humidity treatment at 23° C. and 50% RH Contact angle σ of surface S1 with water 1 is 60° or more and 80° or less, and the temperature is constant at 23°C and 50% RH. The contact angle σ of the film surface S1 of the LCP extruded film with water after 7 days of constant humidity treatment 7 but The contact angle σ is 60° or more and 80° or less. 1 The contact angle σ 7 The decay rate of (( σ 7 -σ 1 ) / σ 1 The LCP having the film surface S1, Obtaining the extruded film, Method for producing LCP extruded film.

16. The linear expansion coefficient of the extruded LCP film in the TD direction is 0 to 55 ppm / K. The extruded LCP film of claim 1 .

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