JP2023070392A - Lcp extruded film for stretching, heat-shrinkable lcp stretched film, insulating material for circuit board, and metal foil-clad laminate - Google Patents

Abstract

To provide an LCP extruded film for stretching or the like that shows excellent stretchability during a stretching process, thereby providing a heat-shrinkable LCP stretched film that has small anisotropy in dimensional change rate and a small absolute value in dimensional change rate.SOLUTION: An LCP extruded film for stretching comprises a thermoplastic liquid crystal polymer. In a stress-strain curve as measured by a thermostat bath tensile test (in accordance with JIS K7161-1: 2014, at 200°C and tensile rate 200 mm/min), a yield point strength X (MPa) and a breaking point strength Y (MPa) of the LCP extruded film for stretching in a TD direction satisfy the following formula (1): 0.75≤breaking point strength Y/yield point strength X≤1.50 (1).SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to an LCP extruded film for stretching treatment, a heat-shrinkable LCP stretched film, an insulating material for circuit boards, a metal foil-clad laminate, and the like.

Conventionally, as an insulating material for a circuit board, a varnish-impregnated composite material obtained by impregnating a glass cloth with a varnish containing a thermosetting resin such as an epoxy resin, an inorganic filler, a solvent, and the like and then heat-press molding is known. However, this manufacturing method has a poor process margin during manufacturing and is inferior in productivity from the viewpoint of, for example, resin flowability during varnish impregnation and curability during hot press molding. In addition, the thermosetting resin easily absorbs moisture, and its dimensions change as it absorbs moisture, so the resulting varnish-impregnated composite material is inferior in dimensional accuracy (heating dimensional accuracy).

On the other hand, a liquid crystal polymer (LCP) is a polymer that exhibits liquid crystallinity in a molten state or a solution state. In particular, thermotropic liquid crystal polymers, which exhibit liquid crystallinity in a molten state, can be extruded and have excellent gas barrier properties, high film strength, high heat resistance, high insulation, low water absorption, and low dielectric properties in the high frequency range. It has the characteristic Therefore, films using thermoplastic liquid crystal polymers are being studied for practical use in gas barrier film material applications, electronic material applications, and electrical insulating material applications.

However, when single-layer extrusion molding is actually performed, due to the high degree of liquid crystal orientation of thermoplastic liquid crystal polymer, thermoplastic liquid crystal polymer films with high industrial value, that is, excellent thickness accuracy, appearance and appearance. It has been found difficult to obtain a thermoplastic liquid crystal polymer film with good surface flatness.

Therefore, for example, in Patent Document 1, a three-layer co-extrusion die is used instead of a single-layer extrusion die, and a wholly aromatic polyester thermotropic liquid crystal polymer is used as an intermediate layer to simultaneously extrude a polyolefin resin or a polycarbonate resin as both outer layers. Then, by molding a three-layer laminated film in which the intermediate layer is a thermoplastic liquid crystal polymer layer and both outer layers are thermoplastic resin layers, the thermoplastic resin layers of both outer layers are peeled off and the intermediate layer is taken out as a film, It is disclosed that a thermoplastic liquid crystal polymer film having excellent thickness precision and good appearance and surface flatness can be obtained.

Further, for example, in Patent Document 2, in the thermoplastic liquid crystal polymer film described in Patent Document 1, the strength in the TD direction (Transverse Direction; transverse direction) relative to the MD direction (Machine Direction; longitudinal direction) is practically unbearable. By using a feed block type three-layer co-extrusion die instead of a multi-manifold type co-extrusion die, the strength in the TD direction and MD direction (machine direction; longitudinal direction) of the thermoplastic liquid crystal polymer film obtained It is disclosed that the anisotropy of is relaxed.

JP-A-63-31729 JP-A-2-178016

Insulating materials for circuit boards using liquid crystal polymer are excellent in high frequency characteristics and low dielectric properties. In recent years, it has been spotlighted as an insulating material for circuit boards such as printed wiring board laminates and fiber-reinforced flexible laminates.

The techniques described in Patent Literatures 1 and 2 described above are said to be capable of realizing a thermoplastic liquid crystal polymer film with excellent thickness accuracy and good appearance and surface flatness. However, in reality, although it is possible to suppress the peeling of the skin layer and the peeling of the fibrillated fibers caused by the highly molecular orientation of the thermoplastic liquid crystal polymer on the film surface, the thermoplastic liquid crystal polymer described in Patent Documents 1 and 2 can be suppressed. In the liquid crystal polymer film as a whole, the thermoplastic liquid crystal polymer is still highly molecularly oriented, and it was not practically durable as an insulating material for circuit boards.

Specifically, in applications as an insulating material 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 a copper foil to one side and/or both sides of the film. be. By pattern-etching the metal foil to form fine wiring or the like, the metal foil-clad laminate can be used as a material for circuit boards such as electronic circuit boards and multilayer boards. Therefore, the thermoplastic liquid crystal polymer film that supports the metal foil is required to have high dimensional stability. However, the thermoplastic liquid crystal polymer films described in Patent Documents 1 and 2 still have a large difference in the dimensional change rate in the TD direction and the MD direction after etching, and cannot meet the recent demands for application to ultrafine processing. rice field.

The present invention has been made in view of the above problems. An object of the present invention is to provide a heat-shrinkable LCP stretched film having excellent stretchability during stretching and thus anisotropic dimensional change rate and a small absolute value of dimensional change rate. to provide the film. Another object of the present invention is to provide a heat-shrinkable stretched LCP film having an anisotropic dimensional change rate and a small absolute value of the dimensional change rate, and an insulating material for circuit boards and a metal foil-clad laminate using the same. etc. is to be provided.

As a result of intensive studies to solve the above problems, the present inventors found that an LCP extruded film having a predetermined tensile property is excellent in stretchability during stretching, and that the dimensional change rate is reduced by stretching. The inventors have found that a heat-shrinkable stretched LCP film with small absolute values of anisotropy and dimensional change can be realized, and have completed the present invention.

That is, the present invention provides various specific aspects shown below.
(1) It is an LCP extruded film for stretching treatment containing a thermoplastic liquid crystal polymer, and is measured by a constant temperature bath tensile test (JIS K7161-1: 2014 compliant, 200 ° C., tensile speed 200 mm / min) In the stress-strain curve, The LCP extruded film for stretching, wherein the yield point strength X (MPa) and breaking point strength Y (MPa) in the TD direction of the LCP extruded film for stretching satisfy the following formula (1).
0.75≦strength at breaking point Y/strength at yield point X≦1.50 (1)

(2) The LCP extruded film for stretching according to (1), wherein the LCP extruded film for stretching has a coefficient of linear expansion in the TD direction of 5 to 55 ppm/K.

(3) The LCP extruded film for stretching according to (1) or (2), wherein the LCP extruded film for stretching is a T-die extruded film.

(4) The LCP extruded film for stretching treatment is the intermediate layer obtained by removing the outer layers from the laminated extruded film having the outer layer, the intermediate layer, and the outer layer. LCP extruded film for stretch processing as described.

(5) The LCP extruded film for stretching treatment does not have a tape-peelable skin layer on the film surface in an adhesion test by a cross-cut method in accordance with JIS K5600-5-6 of (1) to (4). The LCP extruded film for stretch processing according to any one of claims 1 to 3.

(6) The LCP extruded film for stretching according to any one of (1) to (5), which has a thickness of 15 μm or more and 300 μm or less.

(7) The LCP extruded film for stretching according to any one of (1) to (6), further comprising an inorganic filler.

(8) A stretched body of the LCP extruded film for stretching treatment according to any one of (1) to (7), wherein the linear expansion coefficient in the TD direction of the stretched body is −20 ppm/K or more and 0 ppm/K. and the stretched body has a linear expansion coefficient in the MD direction of -20 ppm/K or more and less than 0 ppm/K.

(9) The heat-shrinkable LCP stretched film according to (8), wherein the stretched body has a stretch ratio of 1.3 to 2.5 times in the TD direction with respect to the LCP extruded film for stretching treatment.

(10) An insulation for a circuit board, comprising a laminate having at least the heat-shrinkable LCP stretched film according to (8) or (9) and a woven fabric provided on at least one surface of the heat-shrinkable LCP stretched film. material.

(11) A metal foil-clad laminate comprising the heat-shrinkable LCP stretched film according to (8) or (9) and a metal foil provided on one side and/or both sides of the heat-shrinkable LCP stretched film.

(14) A metal foil comprising a laminate having at least the heat-shrinkable LCP stretched film and the woven fabric according to (8) or (9), and a metal foil provided on one side and/or both sides of the laminate. tension laminate.

According to one aspect of the present invention, the stretching process is excellent in stretchability during the stretching process, and thereby can realize a heat-shrinkable LCP stretched film with an anisotropic dimensional change rate and a small absolute value of the dimensional change rate. for LCP extruded films and the like can be realized. In addition, according to one aspect of the present invention, a novel heat-shrinkable LCP stretched film having a small anisotropy of dimensional change rate and a small absolute value of dimensional change rate, and an insulating material for circuit boards using the same, Metal foil clad laminates and the like can be realized. Therefore, according to various aspects of the present invention, it is possible to realize highly reliable products adapted to recent ultra-fine processing.

1 is a graph showing an example of a stress-strain curve in the TD direction of an LCP extruded film for stretching treatment of the present invention. 1 is a graph showing an example of a stress-strain curve in the TD direction of an LCP extruded film for stretching treatment of the present invention. 1 is a graph showing an example of a stress-strain curve in the TD direction of a prior art LCP extruded film for stretching. FIG. 4 is a diagram showing a co-extrusion method of an LCP extruded film for stretch processing in one embodiment. FIG. 4 is a diagram showing a co-extrusion method of an LCP extruded film for stretch processing in one embodiment. FIG. 4 is a diagram showing a co-extrusion method of an LCP extruded film for stretch processing in one embodiment. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic cross section which shows the insulating material for circuit boards of one Embodiment. 1 is a schematic cross-sectional view showing a metal foil-clad laminate of one embodiment; FIG. 1 is a schematic cross-sectional view showing a metal foil-clad laminate of one embodiment; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Unless otherwise specified, positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings. Also, the dimensional ratios in the drawings are not limited to the illustrated ratios. 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 arbitrarily modified and implemented without departing from the gist thereof. In this specification, 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 notation of other numerical ranges.

(LCP extruded film for stretching treatment)
The LCP extruded film for stretching treatment of the present embodiment is an LCP extruded film (stretched LCP extruded film) that contains a thermoplastic liquid crystal polymer and can be uniformly stretched during the stretching treatment.

As mentioned above, the LCP extruded film of the prior art is characterized by extreme molecular orientation of the thermoplastic liquid crystal polymer on the film surface, such as peeling of the skin layer and fibrillated fibers on the film surface. there were. It is presumed that this is because the thermoplastic liquid crystal polymer is highly oriented on the surface of the extruded body as a result of receiving shear stress from the side of the apparatus during extrusion. Even in the conventional LCP extruded film in which the thermoplastic liquid crystal polymer is highly oriented in this way, by applying a stretching treatment, the anisotropy of the dimensional change rate and the absolute value of the dimensional change rate are small. However, according to the findings of the present inventors, the LCP extruded film of the prior art has almost no stretching aptitude during the stretching process, and an industrially useful LCP stretched film is obtained. has proved to be practically difficult. Specifically, the LCP extruded film of the prior art, for example, is unevenly stretched even if it is stretched at a draw ratio of 1.1 times in the TD direction. , the film does not have aptitude for stretching, such as film breakage. On the other hand, it was confirmed that the extreme molecular orientation on the film surface of the thermoplastic liquid crystal polymer was alleviated by the improvement as in Patent Documents 1 and 2, but at the same time, the molecules of the thermoplastic liquid crystal polymer on the film surface The present inventors have found that it is not possible to achieve the required performance as an insulating material for a circuit board only by controlling the orientation.

The LCP extruded film for stretching treatment (stretched LCP extruded film) of the present embodiment has been studied from this point of view. That is, the LCP extruded film for stretching treatment (stretched LCP extruded film) of the present embodiment has a good stretchability at least in the TD direction by having a predetermined tensile property, and therefore it was difficult with the conventional technology. Uniform stretching is possible. Then, by stretching the LCP extruded film to be stretched, the molecular orientation and internal strain of the thermoplastic liquid crystal polymer occurring on the film surface and/or inside the film are reduced. It is possible to realize a heat-shrinkable stretched LCP film with small absolute values of elasticity and dimensional change rate.

The thermoplastic liquid crystal polymer contained in the LCP extruded film for stretching treatment can be one known in the art, and the type is not particularly limited. A liquid crystal polymer is a polymer that forms an optically anisotropic molten phase, and typically includes a thermotropic liquid crystal compound. The properties of the anisotropic molten phase can be confirmed by a known method such as polarization inspection using crossed polarizers. More specifically, confirmation of the anisotropic molten phase can be carried out by using a Leitz polarizing microscope and observing a sample placed on a Leitz hot stage under a nitrogen atmosphere at a magnification of 40 times.

Specific examples of thermoplastic liquid crystal polymers include monomers such as aromatic or aliphatic dihydroxy compounds, aromatic or aliphatic dicarboxylic acids, aromatic hydroxycarboxylic acids, aromatic diamines, aromatic hydroxylamines, and aromatic aminocarboxylic acids. Examples include, but are not limited to, those obtained by polycondensation. The thermoplastic liquid crystal polymer is preferably a copolymer. Specifically, aromatic polyamide resins obtained by polycondensation of monomers such as aromatic hydroxycarboxylic acids, aromatic diamines, aromatic hydroxyamines; aromatic diols, aromatic carboxylic acids, aromatic hydroxycarboxylic acids, etc. (Whole) aromatic polyester resin obtained by polycondensation of the monomers; but not limited to these. These can be used individually by 1 type or in arbitrary combinations and ratios of 2 or more types.

Thermoplastic liquid crystal polymers are generally classified into type I, type II, type III, etc. in terms of heat distortion temperature (TDUL). Any type of thermoplastic liquid crystal polymer can be suitably used for the LCP extruded film for stretching treatment of the present embodiment, and may be appropriately selected according to the application. For example, in electronic circuit board applications that require application to lead-free solder of 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 TDUL of about 240 to 250 ° C. A type II thermoplastic liquid crystal polymer having relatively high heat resistance is preferably used.

Among these, (wholly) aromatic polyester resins exhibiting thermotropic liquid crystal-like properties and having a melting point of 250° C. or higher, preferably 280° C. to 380° C., are preferably used. As such a (wholly) aromatic polyester resin, for example, a (wholly) aromatic polyester resin that exhibits liquid crystallinity when melted and synthesized from monomers such as aromatic diols, aromatic carboxylic acids, and hydroxycarboxylic acids is known. It is Typical examples include polycondensates of ethylene terephthalate and parahydroxybenzoic acid, polycondensates of phenol, phthalic acid and parahydroxybenzoic acid, and polycondensates of 2,6-hydroxynaphthoic acid and parahydroxybenzoic acid. Examples include polycondensates, but are not particularly limited thereto. In addition, the (totally) aromatic polyester resin can be used alone or in any combination and ratio of two or more. Depending on the required performance, a highly heat-resistant wholly aromatic polyester resin with a relatively high melting point or high heat distortion temperature is used, or an aromatic polyester resin with a relatively low melting point or low heat distortion temperature and excellent moldability is used. Resin can be used.

In a preferred embodiment, the basic structure is 6-hydroxy-2-naphthoic acid and its derivatives (hereinafter sometimes simply referred to as "monomer component A"), and parahydroxybenzoic acid, terephthalic acid, isophthalic acid, 6-naphthalenedicarboxylic acid, 4,4'-biphenol, bisphenol A, hydroquinone, 4,4-dihydroxybiphenol, ethylene terephthalate and one or more selected from the group consisting of derivatives thereof as a monomer component (hereinafter simply " may be referred to as "monomer component B"). Such a (totally) aromatic polyester resin forms an anisotropic melt phase in which linear chains of molecules are regularly arranged in a molten state, and typically exhibits thermotropic liquid crystal-like properties, mechanical properties, It has excellent basic performance in electrical properties, high frequency properties, heat resistance, hygroscopicity and the like.

In addition, the (totally) aromatic polyester resin of one preferred embodiment described above can have any configuration 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 monomer components A, or three or more monomer components A. In addition, the (totally) aromatic polyester resin of one preferred embodiment described above contains other monomer components (hereinafter sometimes simply referred to as "monomer component C") other than the monomer component A and the monomer component B. You may have That is, the (totally) aromatic polyester resin of one preferred embodiment described above is a binary or higher polycondensate consisting only of the monomer component A and the monomer component B, and the monomer component A, the monomer component B, and the monomer component Polycondensates of ternary or higher monomer components consisting of C may also be used. Other monomer components include those other than the monomer component A and monomer component B described above, specifically aromatic or aliphatic dihydroxy compounds and derivatives thereof; aromatic or aliphatic dicarboxylic acids and derivatives thereof; acids and their derivatives; aromatic diamines, aromatic hydroxylamines or aromatic aminocarboxylic acids and their derivatives; and the like, but are not particularly limited thereto. Other monomer components can be used singly or in any combination and ratio of two or more.

In the present specification, the term "derivative" means that a part of the above-described monomer components includes a halogen atom (eg, fluorine atom, chlorine atom, bromine atom, iodine atom), an alkyl group having 1 to 5 carbon atoms (eg, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, etc.), aryl group such as phenyl group, hydroxyl group, alkoxy group having 1 to 5 carbon atoms (for example, methoxy group, ethoxy group, etc.), carbonyl group, -O-, -S-, -CH ₂ -, etc. (hereinafter referred to as "monomer component having a substituent" There is.) means. Here, the "derivative" may be an ester-forming monomer such as an acylated product, an ester derivative, or an acid halide of the monomer components A and B which may have a modifying group as described above.

A particularly preferred embodiment includes binary polycondensates of parahydroxybenzoic acid and its derivatives and 6-hydroxy-2-naphthoic acid and its derivatives; parahydroxybenzoic acid and its derivatives and 6-hydroxy-2-naphthoate Ternary or higher polycondensates of acids and derivatives thereof and monomer component C; , 4,4′-biphenol, bisphenol A, hydroquinone, 4,4-dihydroxybiphenol, ethylene terephthalate and derivatives thereof; Benzoic 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 quaternary or higher polycondensates consisting of one or more monomer components C and one or more selected from the group consisting of terephthalate and derivatives thereof; These can be obtained, for example, as those having a relatively low melting point compared to homopolymers of parahydroxybenzoic acid, etc. Therefore, the thermoplastic liquid crystal polymer using these can be used during thermocompression bonding to an adherend. It becomes excellent in moldability.

The melting point of the (totally) aromatic polyester resin is lowered, the LCP extruded film for stretching treatment or its stretched body is enhanced in moldability at the time of thermocompression bonding to an adherend, or the LCP extruded film for stretching treatment or its stretched body is improved. From the viewpoint of obtaining a high peel strength when the is thermocompression bonded to a metal foil, the content ratio of the monomer component A in terms of the molar ratio with respect to the (totally) aromatic polyester resin is preferably 10 mol% or more and 90 mol% or less. 30 mol % or more and 85 mol % or less is more preferable, and 50 mol % or more and 80 mol % or less is even more preferable. Similarly, the content ratio of the monomer component B in terms of molar ratio to the (total) 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 20 mol% or more. 50 mol % or less is more preferable. In addition, the content of the monomer component C that may be contained in the (total) aromatic polyester resin is preferably 10 mol% or less, more preferably 8 mol% or less, still more preferably 5 mol% or less in terms of molar ratio. , and particularly preferably not more than 3 mol %.

The method for synthesizing the (totally) aromatic polyester resin is not particularly limited and a known method can be applied. A known polycondensation method for forming an ester bond by the monomer components described above, such as melt polymerization, melt acidolysis, slurry polymerization, or the like, can be applied. When applying these polymerization methods, an acylation or acetylation step may be performed according to a conventional method.

The LCP extruded film for stretching treatment may further contain an inorganic filler. By containing an inorganic filler, it is possible to realize an LCP extruded film for stretching treatment with a reduced coefficient of linear expansion. It is easy to obtain an LCP extruded film for stretching treatment with reduced anisotropy of the coefficient of linear expansion. Such an LCP extruded film for stretching treatment is particularly useful for applications such as rigid substrates that require multi-layer lamination.

Any inorganic filler known in the art can be used, 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, calcium hydroxide, calcium sulfate, calcium sulfite, calcium borate, etc.), molybdenum compounds (e.g., molybdenum oxide, zinc molybdate, etc.), talc (e.g., natural talc, calcined talc, etc.), mica (mica), titanium oxide, zinc oxide, zirconium oxide, barium sulfate, stannates such as zinc borate, barium metaborate, sodium borate, boron nitride, aggregated boron nitride, silicon nitride, carbon nitride, strontium titanate, barium titanate, and zinc stannate; Not limited. These can be used individually by 1 type, and can also be used in combination of 2 or more type. Among these, silica is preferable from the viewpoint of dielectric properties and the like.

Moreover, the inorganic filler used here may be subjected to a surface treatment known in the art. Moisture resistance, adhesive strength, dispersibility, etc. can be improved by surface treatment. Examples of surface treatment agents include silane coupling agents, titanate coupling agents, sulfonic acid esters, carboxylic acid esters, and phosphoric acid esters, but are not particularly limited thereto.

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, effect of reducing the linear expansion coefficient, etc., the d50 of the inorganic filler is preferably 0.01 μm or more and 50 μm or less, more preferably 0.03 μm or more and 50 μm or less, further preferably 0.01 μm or more and 50 μm or less. It is 1 μm or more and 50 μm or less. In this specification, the median diameter (d50) of the inorganic filler is measured on a volume basis by a laser diffraction/scattering method using a laser diffraction/scattering particle size distribution analyzer (LA-500 manufactured by Horiba, Ltd.). value.

The content of the inorganic filler is not particularly limited, and can be appropriately set according to the required performance in consideration of the blending balance with other essential components and optional components. From the viewpoint of kneadability and handleability during preparation, the effect of reducing the coefficient of linear expansion, etc., the total content of the inorganic filler is 1% by mass or more and 45% by mass in terms of solid content with respect to the total amount of the LCP extruded film for stretching treatment. The following are preferable, more preferably 3% by mass or more and 40% by mass or less in total, and still more preferably 5% by mass or more and 35% by mass or less in total.

The LCP extruded film for stretching treatment includes resin components other than the above-described thermoplastic liquid crystal polymer (hereinafter sometimes simply referred to as "other resin components"), such as A thermosetting resin, a thermoplastic resin, or the like may be contained. In addition, the LCP extruded film for stretching treatment may contain additives known in the art, such as higher fatty acids having 10 to 25 carbon atoms, higher fatty acid esters, higher fatty acid amides, and higher fatty acids, as long as the effects of the present invention are not excessively impaired. Release improvers such as metal salts, polysiloxanes, and fluorine resins; coloring agents such as dyes and pigments; organic fillers; antioxidants; heat stabilizers; light stabilizers; Surfactants; antirust agents; antifoaming agents; fluorescent agents and the like may be included. These additives can be used singly or in combination of two or more. These additives can be included in the molten resin composition prepared during the molding of the LCP extruded film for stretching. The content of these resin components and additives is not particularly limited, but from the viewpoint of molding processability, thermal stability, etc., each is preferably 0.01 to 10% by mass relative to the total amount of the LCP extruded film for stretching treatment. , more preferably 0.1 to 7 mass % each, and still more preferably 0.5 to 5 mass % each.

Since the LCP extruded film for stretching treatment of the present embodiment has predetermined tensile properties, unlike the prior art, it has good stretching aptitude at least in the TD direction and can be uniformly stretched during the stretching treatment. Specifically, the LCP extruded film for stretching treatment of the present embodiment has a stress-strain curve measured by a constant temperature bath tensile test (JIS K7161-1: 2014 compliant, 200 ° C., tensile speed 200 mm / min). Yield point strength X (MPa) and breaking point strength Y (MPa) in the TD direction of the LCP extruded film for stretching satisfy the following formula (1).
0.75≦strength at breaking point Y/strength at yield point X≦1.50 (1)

Here, in the tensile test performed in accordance with JIS K7161-1:2014, the test piece is held at a constant speed along the main axis (a constant speed in the direction perpendicular to the cross section of the test piece) until the test piece breaks. d) is a tensile test that measures the force and elongation applied to a specimen. Yield point strength X (MPa) means the highest point in the yield region of the stress-strain curve obtained in the above tensile test, and the higher this value, the stronger the force required to deform the material. . The breaking point strength Y (MPa) means the stress immediately before the test piece breaks in the tensile test, and the higher this value, the stronger force is required to break the material. On the other hand, the breaking point strength Y/yield point strength X means the strength ratio of the breaking point strength Y and the yield point strength X in the stress-strain curve obtained in the tensile test. 1 and 2 are graphs showing an example of stress-strain curves in the TD direction of the LCP extruded film for stretching treatment of the present invention satisfying 0.75≦Y/X≦1.50. FIG. 3 is a graph showing an example of a stress-strain curve in the TD direction of a prior art LCP extruded film for stretch processing corresponding to Y/X<0.75. As can be understood from the comparison of FIGS. 1 to 3, the LCP extruded film for stretching treatment of the present invention has a relatively large strength ratio of breaking point strength Y/yield point strength X compared to the conventional technology. , and has uniform extensibility at a constant load. In addition, the amount of displacement from the yield point strength X to the breaking point strength Y (horizontal axis) correlates with the draw ratio, and a large displacement indicates that a high draw ratio can be applied. . That is, the LCP extruded film for stretching treatment of the present embodiment, which satisfies the above formula (1), can be stretched relatively uniformly and can be stretched at a relatively high draw ratio, unlike the conventional technique. is understood.

Although the value of breaking point strength Y in the TD direction/yield point strength X is not particularly limited, it is preferably 0.80 or more and 1.50 or less, more preferably 0.85 or more and 1.50 or less, and still more preferably. is 0.90 or more and 1.35 or less, particularly preferably 0.90 or more and 1.20 or less. As this value increases, the uniform drawability in the TD direction tends to be enhanced. In this specification, the value of breaking point strength Y/yield point strength X is the average value when the tensile test is performed five times under the conditions described in the examples described later, from the viewpoint of ensuring the measurement accuracy. do.

In addition, the value of breaking point strength Y/yield point strength X in the MD direction is not particularly limited. When uniform stretchability in the MD direction is required, the value of breaking point strength Y/yield point strength X in the MD direction is preferably 0.75 or more and 1.50 or less, more preferably 0.80 or more and 1.50. It is 50 or less, more preferably 0.85 or more and 1.50 or less, and particularly preferably 0.90 or more and 1.50 or less. As this value increases, the uniform stretchability in the MD direction tends to be enhanced.

As the LCP extruded film for stretching treatment, a melt extruded film such as a T-die extruded film is preferably used. Further, as the LCP extruded film for stretching treatment, an intermediate layer (core layer) of a three-layer coextruded film having a laminated structure in which at least a thermoplastic resin layer, a thermoplastic liquid crystal polymer layer, and a thermoplastic resin layer are arranged in this order. A thermoplastic liquid crystal polymer layer 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 for stretching treatment). An extruded film of a thermoplastic liquid crystal polymer can be manufactured at a low cost and in a homogeneous manner as compared with a woven fabric or a nonwoven fabric made of fibers of a thermoplastic liquid crystal polymer.

The thickness of the LCP extruded film for stretching treatment can be appropriately set according to requirements, and is not particularly limited. Considering the handleability and productivity during extrusion molding, the thickness is preferably 15 μm or more and 300 μm or less, more preferably 18 μm or more and 250 μm or less, and still more preferably 20 μm or more and 200 μm or less.

On the other hand, in the LCP extruded film for stretching treatment of the present embodiment, it is preferable that the molecular orientation of the thermoplastic liquid crystal polymer represented by the linear expansion coefficients in the MD direction and the TD direction is sufficiently reduced. As mentioned above, the LCP extruded films described in Patent Documents 1 and 2 of the prior art are protected by the thermoplastic resin layers of both outer layers during coextrusion of the three layers, so that the molecular orientation of the thermoplastic liquid crystal polymer is slightly oriented. It can be seen that the strength anisotropy in the MD and TD directions of the resulting thermoplastic liquid crystal polymer film is relaxed. However, in fact, the LCP extruded films described in Patent Documents 1 and 2 stably have a linear expansion coefficient of about -20 ppm / K in the MD direction, whereas in the TD direction The coefficient of linear expansion exceeds 55 ppm, and sometimes reaches about 100 ppm/K. As is clear from this, in the LCP extruded films described in Patent Documents 1 and 2 of the prior art, the molecular orientation of the thermoplastic liquid crystal polymer still remains large as a whole film, or the internal strain etc. is large. It is easy to see what remains.

The LCP extruded film for stretching treatment of the present embodiment preferably has a coefficient of linear expansion (CTE, α2, 23 to 200° C.) in the MD and TD directions within the range of −30 to 55 ppm/K. The LCP extruded film for stretching, which has a coefficient of linear expansion within such a range, is in a state in which internal strain and the like are reduced, and has a smaller anisotropy in the rate of dimensional change than the film that does not. LCP extruded films for stretch processing with a sufficiently small absolute value of the modulus can be obtained. The coefficient of linear expansion in the MD direction of the LCP extruded film for stretching (CTE, α2, 23-200°C) should be in the range of -30-10 ppm/K from the viewpoint of enhancing the adhesion to the metal foil. is preferably in the range of -25 to 5 ppm/K, and more preferably in the range of -20 to 0 ppm/K. In addition, the coefficient of linear expansion in the TD direction (CTE, α2, 23-200° C.) of the LCP extruded film for stretching treatment is in the range of 0-55 ppm/K from the viewpoint of enhancing the adhesion to the metal foil. preferably in the range of 5 to 55 ppm/K, even more preferably in the range of 5 to 50 ppm/K. In this specification, the coefficient of linear expansion (CTE, α2, 23-200°C) means the value in the temperature range of 23-200°C measured by the TMA method according to JIS K7197. Further, other detailed measurement conditions are in accordance with the conditions described in Examples described later.

On the other hand, the dielectric properties of the LCP extruded film for stretching treatment of the present embodiment can be appropriately set according to the desired performance, and are not particularly limited. From the viewpoint of obtaining higher dielectric properties, the dielectric constant ε _r (36 GHz) is preferably 3.0 or more and 3.7 or less, more preferably 3.0 to 3.5. Similarly, the dielectric loss tangent tan δ (36 GHz) is preferably 0.0010 or more and 0.0050 or less, more preferably 0.0010 or more and 0.0045 or less. In the present specification, relative permittivity ε _r (36 GHz) and dielectric loss tangent tan δ (36 GHz) mean values at 36 GHz measured by the cavity resonator contact motion method conforming to JIS K6471. Further, other detailed measurement conditions are in accordance with the conditions described in Examples described later.

(Manufacturing method of LCP extruded film for stretching treatment)
The LCP extruded film for stretching treatment of the present embodiment is 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. Obtainable. As the extrusion method, various known methods can be applied, and the type is not particularly limited. For example, T-die method or inflation method; for example, multi-manifold type co-extrusion method or feed block type co-extrusion method; for example, multilayer co-extrusion method such as two-layer co-extrusion method or three-layer co-extrusion method; can do.

Among these, 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 preferable embodiment is the resin composition described above, Extruded from a T-die by an extrusion molding method using a die (hereinafter sometimes simply referred to as "T-die extrusion method") to form a film, and then cooled, crimped, and pressurized as necessary. A method of obtaining a predetermined LCP extruded film for stretching treatment by heat treatment or the like can be mentioned. Specifically, the first surface layer resin composition A containing a thermoplastic resin, the intermediate layer resin composition B containing a thermoplastic liquid crystal polymer, the second surface layer resin composition C containing a thermoplastic resin are prepared respectively, and these are coextruded from the coextrusion die of the extruder to extrude the coextruded melt of the three-layer structure to form an LCP extruded film for stretching treatment as the thermoplastic liquid crystal polymer layer of the intermediate layer. A coextrusion method is preferred. According to such co-extrusion molding, the thermoplastic liquid crystal polymer layer of the intermediate layer is protected by the thermoplastic resin layers of both outer layers, so that the molecular orientation of the thermoplastic liquid crystal polymer in the thermoplastic liquid crystal polymer layer of the intermediate layer is relaxed. A preferred aspect of the method for producing an LCP extruded film for stretching according to the present embodiment will be described in detail below.

4 to 6 are diagrams showing a preferred aspect of the method for producing the LCP extruded film for stretching according to the present embodiment described above. Here, the resin composition B containing the thermoplastic liquid crystal polymer described above and optional components such as an inorganic filler and other resin components as necessary is melt-extruded into a film from a T-die of an extruder. At this time, by co-extrusion of the resin compositions A and C containing a thermoplastic resin on both sides of the film-shaped melt extrudate, a first outer layer (peeling layer) containing a thermoplastic resin and a thermoplastic liquid crystal polymer are formed. A coextruded melt (three-layer laminate film) of a predetermined thickness is prepared, having an intermediate layer (LCP layer) containing a thermoplastic resin and a second outer layer (release layer) containing a thermoplastic resin. The coextrusion melt is withdrawn by a take-off roll and sent to a chill roll and a pressure roll. After that, 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 extruded film for stretching treatment) are respectively wound on winding rolls. be taken.

The resin composition B containing the thermoplastic liquid crystal polymer may be prepared according to a conventional method, and is not particularly limited. Each of the components described above can be produced and processed by known methods such as kneading, melt-kneading, granulation, extrusion molding, pressing or injection molding. When performing melt-kneading, a kneading device such as a generally used single-screw or twin-screw extruder or 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 a Henschel mixer. At the time of melt-kneading, the set temperature of the cylinder of the kneading device may be appropriately set and is not particularly limited, but generally the range is preferably from the melting point of the liquid crystal polymer to 360°C, more preferably from the melting point of the liquid crystal polymer + 10°C to 360°C. ℃ or less.

Resin compositions A and C containing a thermoplastic resin may also be prepared according to conventional methods, and are not particularly limited. Examples of thermoplastic resins include polyolefin resins such as polyethylene, polypropylene, polymethylpentene, and ethylene-α-olefin copolymers, acrylic resins such as PMMA, polyamide resins, acrylonitrile-butadiene-styrene copolymers (ABS resin), polystyrene (PS), polyvinyl chloride, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polycarbonate (PC), polyether ether ketone (PEEK), polyphenyl sulfide (PPS), etc. It is not particularly limited to these. Both a polar resin such as polycarbonate and a non-polar resin such as polymethylpentene function effectively as a release layer when co-extruded into a melt. These thermoplastic resins may be blended with optional components such as other resin components and inorganic fillers that may be contained in the LCP extruded film for stretching treatment. The resin composition A and the resin composition C may have the same resin composition or different resin compositions, and even if they contain the same thermoplastic resin, they may have different thermoplastic resins. It may contain a resin. Resin compositions A and C containing thermoplastic resins can be produced and processed by known methods such as kneading, melt-kneading, granulation, extrusion molding, pressing, and injection molding. When performing melt-kneading, a kneading device such as a generally used single-screw or twin-screw extruder or 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. At the time of melt-kneading, the set temperature of the cylinder of the kneading device is not particularly limited, and may be appropriately set at a temperature below the temperature at which the thermoplastic resin is not deteriorated by thermal decomposition. It is the melting point of the thermoplastic resin +10°C or more.

The setting conditions for coextrusion are not particularly limited, and may be appropriately set according to the type and composition of the resin composition to be used, the desired performance of the extruded film, and the like. For example, the set temperature of the cylinder of the extruder may be appropriately set according to the type and composition of the resin composition to be used, the desired performance of the extruded film, etc., and is not particularly limited, but is preferably 230 to 360 ° C. More preferably, it is 280 to 350°C.

In addition, for example, the die width (mm) of the T-die may also be set appropriately according to the type and composition of the resin composition to be used, the desired performance of the extruded film, etc., and is not particularly limited, but generally is preferably 200 to 2000 mm, more preferably 400 to 1500 mm.

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

And, for example, the shear rate (sec ⁻¹ ) of the lip wall surface of the T-die may also be set as appropriate according to the type and composition of the resin composition used, the desired performance of the extruded film, etc., and is particularly limited. Although not required, it is generally preferably 100 to 1500 (sec ^-1 ), more preferably 150 to 1000 (sec ^-1 ).

Similarly, the total discharge rate (mm ³ /sec) of the resin composition from the T-die may be appropriately set according to the type and composition of the resin composition to be used, the desired performance of the desired extruded film, etc. Although not particularly limited, it is generally preferably 500 to 15000 (mm ³ /sec), more preferably 1500 to 10000 (mm ³ /sec).

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 to be used, the desired performance of the extruded film, etc., and is not particularly limited. , generally preferably 10 to 300 (Pa·sec), more preferably 20 to 250 (Pa·sec). In addition, the melt viscosity (Pa sec) of the thermoplastic liquid crystal polymer is measured in accordance with JIS K7199 using a Capillograph 1D (manufactured by Toyo Seiki Seisakusho Co., Ltd.) with a cylinder length of 10.00 mm, a cylinder diameter of 1.00 mm, and a barrel diameter of 1.00 mm. It means the value measured under the condition of 9.55 mm and the conditions (die temperature and shear rate of lip wall surface) in the production of the LCP extruded film for stretching treatment.

Similarly, the take-up speed (mm/sec) of the coextruded film may be appropriately set according to the type and composition of the resin composition to be used, the desired performance of the extruded film, etc., and is not particularly limited. It is generally preferably 15 to 1000 (mm/sec), more preferably 20 to 500 (mm/sec).

Here, from the viewpoint of reducing molecular orientation in the MD direction of the thermoplastic liquid crystal polymer during coextrusion, it is desirable that the shear stress (kPa) during coextrusion is low. When the shear stress during coextrusion is large, the thermoplastic liquid crystal polymer tends to be highly oriented in the MD direction, and internal strain tends to remain. In both cases, the molecular orientation of the thermoplastic liquid crystal polymer tends to be reduced, and the internal strain tends to be less likely to remain. The shear stress (kPa) during co-extrusion is a value represented by the product of the shear rate of the lip wall surface (sec ⁻¹ ) and the melt viscosity of the thermoplastic liquid crystal polymer (Pa·sec). , 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 coextrusion 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. Although the lower limit is not particularly limited, it is preferably 5 kPa or more, more preferably 10 kPa or more, in consideration of productivity and the like.

In addition, from the viewpoint of reducing the molecular orientation in the MD direction of the thermoplastic liquid crystal polymer during coextrusion, it is desirable that the drawdown ratio during coextrusion is low. When the drawdown ratio during coextrusion is large, the thermoplastic liquid crystal polymer tends to be highly oriented in the MD direction, and internal strain tends to remain. Both inside the film, the molecular orientation of the thermoplastic liquid crystal polymer tends to be reduced, and the internal strain tends to be less likely to remain. The drawdown ratio is a value represented by take-up speed (mm/sec)/flow speed of the thermoplastic liquid crystal polymer (mm/sec), and the flow speed of the thermoplastic liquid crystal polymer is the value of the resin composition during coextrusion. It is a value calculated based on the total discharge amount, die width, and 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 still more preferably 3.1 or less. Although the lower limit thereof is not particularly limited, it is preferably 1.0 or more, more preferably 1.2 or more, in consideration of productivity and the like.

The thickness of the obtained LCP extruded film for stretching treatment can be appropriately set according to requirements, and is not particularly limited. Considering the handleability and productivity during extrusion molding, the thickness is preferably 15 μm or more and 300 μm or less, more preferably 18 μm or more and 250 μm or less, and still more preferably 20 μm or more and 200 μm or less.

The melting point (melting temperature) of the obtained LCP extruded film for stretching treatment is not particularly limited, but from the viewpoint of the heat resistance and workability of the film, the melting point (melting temperature) is preferably 200 to 400° C., especially From the viewpoint of enhancing the thermocompression bonding property to metal foil, the temperature is preferably 250 to 360°C, more preferably 260 to 355°C, still more preferably 270 to 350°C, and particularly preferably 275 to 345°C. In this specification, the melting point of the LCP extruded film for stretching treatment is measured using a DSC8500 (manufactured by PerkinElmer), and the extruded film is measured at a temperature range of 30 to 400 ° C. and the extruded film is measured at 20 ° C. After heating (1st heating) at a temperature increase rate of /min, cooling (1st cooling) at a temperature decrease rate of 50 ° C./min, and then performing a second heating (2nd heating) at a temperature increase rate of 20 ° C./min means the melting peak temperature in differential scanning calorimetry (DSC) of Others shall follow the measurement conditions described in Examples described later.

The extruded LCP extruded film for stretching treatment can be used as it is, but if necessary, the orientation (anisotropy) can be further reduced or the internal strain can be reduced by performing a pressure heating step. can be further released, and as a result, an LCP extruded film for stretching processing in which the anisotropy of the dimensional change rate is further reduced and an LCP extruded film for stretching processing in which the absolute value of the dimensional change rate is smaller can be realized. can.

The heating and pressurizing treatment may be performed using a method known in the art, such as contact heat treatment, non-contact heat treatment, and the like, and the type is not particularly limited. For example, heat setting can be performed using known equipment such as a non-contact heater, an oven, a blower, a heat roll, a cooling roll, a heat press, and a double-belt heat press. At this time, if necessary, the surface of the LCP extruded film for stretching treatment can be heat-treated by disposing a release film or porous film known in the art. When performing this heat treatment, from the viewpoint of orientation control, a release film or a porous film is placed on the front and back of the LCP extruded film for stretching treatment, and heat is applied while sandwiching between endless belt pairs of a double belt press machine. A thermocompression molding method is preferably used in which pressure bonding is performed and then the release film or porous film is removed. The thermocompression molding method may be performed with reference to, for example, JP-A-2010-221694. When the LCP extruded film for stretching using the above resin composition is thermocompressed between the pair of endless belts of a double belt press, the processing temperature is set to control the crystalline state of the LCP extruded film for stretching. , preferably at a temperature higher than the melting point of the liquid crystal polymer and at a temperature higher than the melting point by 70°C, more preferably at a temperature higher than the melting point by 5°C or higher, and at a temperature higher than the melting point by 60°C or lower, further preferably at a temperature higher than the melting point by 10°C. above the temperature and below the temperature 50° C. higher than the melting point. The thermocompression bonding conditions at this time can be appropriately set according to the desired performance, and are not particularly limited. is under a surface pressure of 0.6 to 8 MPa and a heating temperature of 260 to 400°C, more preferably 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 preferable to carry out the treatment under conditions of, for example, 200 to 320° C. for 1 to 20 hours.

(LCP stretched film)
The LCP extruded film for stretching treatment described above can be used in the form of LCP stretched film 100 (stretched body of LCP extruded film for stretching treatment) by applying uniaxial and/or biaxial stretching treatment. At this time, the LCP stretched film 100 may be heat-shrinkable or heat-expandable in the TD direction, but is preferably heat-shrinkable in the TD direction. Further, the LCP stretched film 100 may be heat-shrinkable or heat-expandable in the MD direction, but it is preferably heat-shrinkable in the MD direction. In this specification, the heat-shrinkable LCP stretched film means an LCP stretched film having heat-shrinkability in the TD and MD directions. ppm/K) shows a negative value.

The setting conditions for the stretching process may be appropriately set according to the type and composition of the resin composition to be used, the desired performance of the target LCP stretched film 100, etc., and are not particularly limited. In the case of uniaxial stretching, for example, the above LCP extruded film for stretching treatment can be stretched 1.3 to 2.5 times at 90 to 180 ° C. in the TD direction (transverse direction), and then For example, it is preferable to perform heat treatment (heat setting) at 100 to 240° C. for 1 to 600 seconds. The draw ratio in the TD direction is preferably 1.4 to 2.4 times, more preferably 1.5 to 2.3 times, even more preferably 1.6 to 2.3 times. In the case of biaxial stretching, for example, the above-mentioned LCP extruded film for stretching treatment is preferably stretched 1.3 to 2.5 times in the MD direction (machine direction; longitudinal direction) at 70 to 180 ° C. to stretch uniaxially. After making a stretched film, it can be further stretched in the TD direction (Transverse Direction) at 90 to 180 ° C. to 1.1 to 2.5 times, and then, for example, at 100 to 240 ° C. for 1 to 600 seconds. Heat treatment (heat setting) is preferably performed. At this time, simultaneous biaxial stretching can be carried out instead of sequential stretching. The draw ratio is not particularly limited, but from the viewpoint of improving film transportability, releasability, suppressing unevenness in thickness, wrinkles, etc., the total draw ratio in the MD direction × TD direction (the draw ratio in the MD direction is m When the draw ratio in the TD direction is n, the draw ratio represented by m × n) is preferably 1.3 times or more, more preferably 1.4 times or more, further preferably 1.5 times or more, Especially preferably, it is 1.6 times or more. Although the upper limit thereof is not particularly limited, a guideline is 6.0 times or less, preferably 5.0 times or less, more preferably less than 4.0 times, and still more preferably less than 3.0 times. Moreover, in the case of heat setting, methods known in the art, such as contact heat treatment, non-contact heat treatment, etc., can be performed, and the type thereof is not particularly limited. For example, heat setting can be performed using known equipment such as a non-contact heater, an oven, a blower, a heat roll, a cooling roll, a heat press, and a double-belt heat press. At this time, if necessary, a release film or a porous film known in the art can be placed on the surface of the stretched LCP film 100, and heat and pressure treatment can be performed.

The coefficient of linear expansion (CTE, α2, 23 to 200° C.) in the MD direction and the TD direction of the LCP stretched film 100 (stretched LCP extruded film for stretching treatment) can be appropriately set according to the desired performance. Although not limited, from the viewpoint of reducing the anisotropy of the dimensional change rate and the absolute value of the dimensional change rate and improving the adhesion to the metal foil, each is preferably in the range of -20 to 0 ppm / K. , Each is more preferably in the range of -15 to 0 ppm/K, more preferably in the range of -13 to 0 ppm/K, and particularly in the range of -10 to 0 ppm/K. preferable.

(Insulating material for circuit boards)
FIG. 7 is a schematic cross-sectional view showing a main part of the insulating material 200 for circuit boards of this embodiment. The circuit board insulating material 200 of the present embodiment comprises a laminate having at least a woven fabric WF provided on one side and/or both sides of the LCP stretched film 100 (stretched LCP extruded film for stretching treatment). is.

Specifically, the circuit board insulating material 200 includes a laminate having a laminate structure (three-layer structure) in which the stretched LCP film 100, the woven fabric WF, and the stretched LCP film 100 are arranged in at least this order. . In this laminate, one LCP stretched film 100 is provided on the surface side of the woven fabric WF, and the other LCP stretched film 100 is provided on the back side of the woven fabric WF. These three layers are thermo-compressed to form a laminate having a three-layer structure. Although a laminate having a three-layer structure is exemplified here, the present invention can be applied even to a laminate having a two-layer structure in which one LCP stretched film 100 is omitted. Needless to say, a laminated body having a laminated structure of four or more layers can be implemented.

Here, in this specification, "a woven fabric WF is provided on one side and/or both sides of the LCP stretched film 100" means that the LCP stretched film 100 is directly placed on the surface of the woven fabric WF as in the present embodiment. In addition to the above embodiment, an arbitrary layer (for example, a primer layer, an adhesive layer, etc.) not shown is interposed between the LCP stretched film 100 and the woven fabric WF, and the LCP stretched film 100 is separated from the woven fabric WF. It is meant to include arranged aspects.

The woven fabric WF is a fabric in which fibers are woven. The type of fibers 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, inorganic fiber woven fabric WF is preferably used. By thermocompression bonding the inorganic fiber woven fabric WF to the LCP stretched film 100, the anisotropy of the dimensional change rate in the MD direction and the TD direction can be kept small, and in a further preferred embodiment, the dimensional change rate in the MD direction and the TD direction can be kept small. You can make it smaller. A commercially available product can be used as the woven fabric WF, and it can be produced by a method known in the art.

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, spherical glass, inorganic fibers other than glass such as quartz, Examples include, but are not limited to, ceramic fibers such as silica. As the inorganic fiber woven fabric WF, a woven fabric subjected to opening treatment or stuffing treatment is suitable 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 improving the thermocompression bondability with the stretched LCP film 100, a glass cloth subjected to fiber opening treatment or clogging treatment is preferable. A glass cloth surface-treated with a silane coupling agent such as epoxysilane treatment or aminosilane treatment can also be preferably used. The woven fabric WF can be used singly or in combination of two or more.

The thickness of the woven fabric WF can be appropriately set according to the required performance, and is not particularly limited. It is preferably 10 to 300 μm, more preferably 10 to 200 μm, still more preferably 15 to 180 μm, from the viewpoint of lamination property, workability, mechanical strength, and the like.

The total thickness of the circuit board insulating material 200 can be appropriately set according to the required performance, and is not particularly limited. It is preferably 30 to 500 μm, more preferably 50 to 400 μm, even more preferably 70 to 300 μm, particularly preferably 90 to 250 μm, from the viewpoint of lamination property, workability, mechanical strength, and the like.

By adopting the above-described configuration, the insulating material 200 for a circuit board of the present embodiment has small anisotropy in the rate of dimensional change in the MD and TD directions. It has remarkable effects of being able to reduce the modulus itself, being excellent in dielectric properties in a high frequency range, being easy to manufacture, and being excellent in productivity.

The circuit board insulating material 200 described above can be manufactured by appropriately applying a known manufacturing method, and the manufacturing method is not particularly limited. To give an example, for example, the LCP stretched film 100 and the woven fabric WF are laminated, heated and pressed, and the LCP stretched film 100 and the woven fabric WF are thermocompressed to obtain the circuit board insulating material 200. can be done. In addition, the LCP stretched film 100, the woven fabric WF, and the LCP stretched film 100 are laminated in this order to form a laminate, and the laminate is sandwiched using a press machine, a double belt press machine, or the like, and heated and pressurized, A method of hot-pressing the circuit board insulating material 200 is also preferred. 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 still more preferably 270 to 350 ° C. be. The processing temperature during thermocompression bonding is the value measured at the surface temperature of the LCP stretched film 100 of the laminate described above. In addition, the pressurization conditions at this time can be appropriately set according to the desired performance, and are not particularly limited. 1 to 120 minutes at 8 MPa.

(metal foil clad laminate)
FIG. 8 is a schematic cross-sectional view showing the main part of the metal foil-clad laminate 300 of this embodiment. The metal foil-clad laminate 300 of this embodiment comprises the LCP stretched film 100 and the metal foil MF provided on one side and/or both sides of the LCP stretched film 100 .

Specifically, the metal foil-clad laminate 300 is a double-sided metal foil-clad laminate having a laminated structure (three-layer structure) in which at least the metal foil MF, the LCP stretched film 100, and the metal foil MF are arranged in this order. be. These three layers are thermo-compressed to form a laminate having a three-layer structure. In this embodiment, a double-sided metal foil-clad laminate is shown, but the present invention can also be implemented in a mode in which only one surface of the stretched LCP film 100 is provided with the metal foil MF. That is, although a laminate having a three-layer structure is exemplified here, the present invention further laminates the LCP stretched film 100 and the woven fabric WF even in a laminate having a two-layer structure in which one of the metal foils MF is omitted. Needless to say, a laminate having a laminate structure of four or more layers can also be implemented.

FIG. 9 is a schematic cross-sectional view showing the main part of the metal foil-clad laminate 400 of this embodiment. The metal foil-clad laminate 400 of the present embodiment includes a laminate having at least the LCP stretched film 100 and the above-described woven fabric WF provided on one side and/or both sides of the LCP stretched film 100, and this laminate and a metal foil MF provided on one side and/or both sides.

Specifically, the metal foil-clad laminate 400 has a laminated structure (five-layer structure) in which at least the metal foil MF, the LCP stretched film 100, the woven fabric WF, the LCP stretched film 100, and the metal foil MF are arranged in this order. It is a double-sided metal foil clad laminate having These five layers are thermo-compressed to form a laminate having a five-layer structure. Although the double-sided metal foil-clad laminate is shown in this embodiment, the present invention can also be implemented as a mode in which the metal foil MF is provided only on one surface. That is, although a laminate having a five-layer structure is exemplified here, the present invention can be applied to a laminate having a four-layer structure in which one metal foil MF is omitted. Needless to say, a laminate having a laminate structure of six or more layers in which woven fabrics WF are further laminated can be implemented.

The material of the metal foil MF is not particularly limited, but gold, silver, copper, copper alloys, nickel, nickel alloys, aluminum, aluminum alloys, iron, iron alloys, and the like can be mentioned. Among these, copper foil, aluminum foil, stainless steel foil, and copper-aluminum alloy foil are preferable, and copper foil is more preferable. As such a copper foil, any one manufactured by a rolling method, an electrolysis method, or the like can be used, but an electrolytic copper foil or a rolled copper foil, which has a relatively large surface roughness, is preferable.

The thickness of the metal foil MF can be appropriately set according to the desired performance, and is not particularly limited. It is usually preferably 1.5 to 1000 μm, more preferably 2 to 500 μm, still more preferably 5 to 150 μm, particularly preferably 7 to 100 μm. In addition, the metal foil MF may be subjected to surface treatment such as chemical surface treatment such as acid cleaning as long as the effects of the present invention are not impaired. The type and thickness of the metal foil MF may be the same or different.

The method of providing the metal foil MF on the surface of the stretched LCP film 100 or the insulating material for circuit board 200 can be carried out according to a conventional method, and is not particularly limited. A method of laminating a metal foil MF on the stretched LCP film 100 or the insulating material 200 for a circuit board and bonding or crimping both layers, a physical method (dry method) such as sputtering or vapor deposition, electroless plating or after electroless plating A chemical method (wet method) such as electrolytic plating, a method of applying a metal paste, or the like may be used. In addition, a laminate obtained by laminating the LCP stretched film 100 or the insulating material for circuit board 200 and one or more metal foils MF is heated using, for example, a multistage press machine, a multistage vacuum press machine, a continuous molding machine, an autoclave molding machine, or the like. Metal foil-clad laminates 300 and 400 can also be obtained by pressing.

The metal foil-clad laminates 300 and 400 described above can be manufactured by appropriately applying a known manufacturing method, and the manufacturing method is not particularly limited. To give an example, for example, the LCP stretched film 100 or the insulating material 200 for circuit boards and the metal foil MF are superimposed to form a laminate in which the metal foil MF is placed on the LCP stretched film 100, and this laminate is doubled. A method of thermocompression molding while sandwiching between a pair of endless belts of a belt press can be used. As described above, the LCP stretched film 100 used in the present embodiment has small anisotropy in the dimensional change rates in the MD and TD directions, and in a more preferred embodiment, the dimensional change rates in the MD and TD directions are small. A high peel strength to the metal foil MF is obtained.

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 at least 50° C. lower than the melting point of the liquid crystal polymer and at most 50° C. higher than the melting point. It is 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 20°C lower than the melting point. A temperature not higher than 20° C. above the melting point is particularly preferred. Note that the temperature during thermocompression bonding of the metal foil MF is the value measured at the surface temperature of the LCP stretched film 100 described above. In addition, the crimping conditions at this time can be appropriately set according to the desired performance, and are not particularly limited. conditions are preferred.

The metal foil-clad laminates 300 and 400 of the present embodiment may have another laminated structure or a further laminated structure as long as they are provided with a two-layer thermocompression bonded body of the stretched LCP film 100 and the metal foil MF. . For example, a two-layer structure of metal foil MF/LCP stretched film 100; a three-layer structure such as metal foil MF/LCP stretched film 100/metal foil MF, LCP stretched film 100/metal foil MF/LCP stretched film 100; metal foil MF /LCP stretched film 100/woven fabric WF/4-layer structure such as LCP stretched film 100; metal foil MF/LCP stretched film 100/metal foil MF/LCP stretched film 100/metal foil MF, metal foil MF/LCP stretched film 100/woven fabric WF/LCP stretched film 100/five-layer structure such as metal foil MF; Also, a plurality of (for example, 2 to 50) metal foil-clad laminates 300 and 400 can be laminated and thermocompressed.

In the metal foil clad laminates 300 and 400 of the present embodiment, the peel strength between the stretched LCP film 100 and the metal foil MF is not particularly limited, but from the viewpoint of providing higher peel strength, it is 0.8 (N/mm ) or more, more preferably 1.0 (N/mm) or more, and still more preferably 1.2 (N/mm) or more. As described above, the metal foil-clad laminates 300 and 400 of the present embodiment can achieve high peel strength, so that peeling between the LCP stretched film 100 and the metal foil MF can be suppressed during the heating process of manufacturing the substrate, for example. In addition, since it is possible to apply manufacturing conditions with excellent process tolerance and productivity in obtaining peel strength equivalent to that of conventional technology, the basic performance of liquid crystal polymer is deteriorated while maintaining peel strength at the same level as conventional technology. can be suppressed.

Then, the metal foil-clad laminates 300 and 400 of the present embodiment can be used as materials for circuit boards such as electronic circuit boards and multilayer boards by pattern-etching at least part of the metal foil MF. In addition, the metal foil-clad laminates 300 and 400 of the present embodiment are excellent in dielectric properties in a high frequency range, have small anisotropy in the rate of dimensional change in the MD direction and the TD direction, and Insulating materials such as flexible printed wiring boards (FPC) for 5th generation mobile communication systems (5G) and millimeter wave radars, etc. It is a particularly useful material as

EXAMPLES The features of the present invention will be described in more detail with reference to Examples and Comparative Examples below, but the present invention is not limited to them in any way. That is, materials, usage amounts, ratios, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the gist of the present invention. In addition, various production conditions and values of evaluation results in the following examples have the meaning of preferable upper limits or preferable lower limits in the embodiments of the present invention, and preferable numerical ranges are the above upper limits or lower limits. A range defined by a combination of a value and a value in the following example or values between examples may be used.

[Melt viscosity]
The melt viscosities [Pa·sec] of the LCP extruded films for stretching were measured under the following conditions.
Measuring instrument: Capilograph 1D (manufactured by Toyo Seiki Seisakusho)
Equipment used: Cylinder length 10.00mm, cylinder diameter 1.00mm, barrel diameter 9.55mm
Measurement conditions: Temperature [°C] and shear rate [sec ^-1 ] during extrusion molding of LCP extruded film for stretching treatment

[Yield point strength X and breaking point strength Y]
A tensile test was performed on the LCP extruded film for stretching treatment under the following conditions, and the yield point strength X and breaking point strength Y were determined.
JIS K7161-1: 2014 compliant Tensile tester: Strograph VE1D (manufactured by Toyo Seiki Seisakusho)
Sample size: Dumbbell type Conditioning before test: 23°C, 50RH% for 24 hours Measurement temperature: 200°C
Tensile speed: 200mm/min
Gauge distance: 50mm
Measurement result: Average value of 5 measurements

[Linear expansion coefficient]
The linear expansion coefficients of the LCP extruded film for stretching treatment and the LCP stretched film were measured by the TMA method according to JIS K7197.
Measuring instrument: TMA 4000SE (manufactured by NETZSCH)
Measurement method: Tensile mode Measurement conditions: Sample size 25 mm × 4 mm × thickness 50 μm
Distance between chucks 20mm
Temperature range 23-200°C (2nd RUN)
Heating rate 5°C/min
Atmosphere nitrogen (flow rate 50 ml/min)
Test load 5gf
* Adopt the value of 2nd RUN in order to see the value with the thermal history eliminated.

[Tape peeling test]
The film surface of the LCP extruded film for stretching treatment was subjected to an adhesion test by a cross-cut method according to JIS K5600-5-6 to confirm the presence or absence of a skin layer. At this time, Nichiban's Cellotape (registered trademark) with a width of 24 mm and a length of 50 mm was used. Yes."
○ No skin layer × With skin layer

(Examples 1-3)
As an intermediate layer, a type I thermoplastic liquid crystal polymer (monomer composition: 79 mol% p-hydroxybenzoic acid, 20 mol% 6-hydroxy-2-naphthoic acid, 1 mol% terephthalic acid copolymer, temperature 330°C, shear rate 500 sec ^-1 The melt viscosity of 70 Pa sec), using polycarbonate PC (Teijin Panlite L-1225L) as the surface layer on both sides of the intermediate layer, under the conditions of a shear stress of 40 kPa and a drawdown ratio of 2.0, the die Each resin is coextruded at 330 ° C. by a T die casting method from a two-kind three-layer extruder equipped with a T die with a width of 600 mm and a lip opening of 0.2 to 1.0 mm, and the intermediate layer has a thickness shown in Table 1. A two-kind three-layer film was molded. Both surface polycarbonate films were peeled off from the molded two-kind three-layer film on a winding line to obtain LCP extruded films for stretching treatment of Examples 1 to 3 having a melting point of 315°C.

The obtained LCP extruded films for stretching treatment of Examples 1 to 3 were each stretched at 130°C in the TD direction by 2.0 times (total stretch ratio: 2.0 times) with a uniaxial stretching machine, and stretched at 130°C. The LCP stretched films of Examples 1 to 3 were obtained by heat setting for 30 seconds at . After that, a glass cloth (IPC No. #1037) is sandwiched between each pair of LCP stretched films of Examples 1 to 3, and a heat press is used to perform thermocompression bonding at 300 ° C. for 5 minutes. Thus, insulating materials for circuit boards of Examples 1 to 3 were obtained.

(Comparative example 1)
Under the conditions of shear stress of 50 kPa and drawdown ratio of 6.0, a liquid crystal polymer is cast at 330° C. from a single 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. An LCP extruded film for stretching treatment of Comparative Example 1 having a melting point of 315° C. was obtained in the same manner as in Example 1 except for the extrusion.

An attempt was made to obtain an LCP stretched film in the same manner as in Example 1 except that the obtained LCP extruded film for stretching treatment of Comparative Example 1 was used, but uniform stretching could not be carried out.

Table 1 shows the results.

(Examples 4-6)
Type II thermoplastic liquid crystal polymer (monomer composition: 74 mol% p-hydroxybenzoic acid, 26 mol% 6-hydroxy-2-naphthoic acid, copolymer, melt viscosity at 300°C and shear rate of 500 sec ^-1 : 80 Pa) was used as the intermediate layer. · sec), using polycarbonate PC (Panlite L-1225L manufactured by Teijin) as the surface layers on both sides of the intermediate layer, under the conditions of a shear stress of 40 kPa and a drawdown ratio of 2.0, a die width of 600 mm and a lip opening. Each resin is co-extruded at 300 ° C. by a T-die casting method from a two-kind three-layer extruder equipped with a T die of 0.2 to 1.0 mm, and the intermediate layer has a thickness shown in Table 2 Two-kind three-layer having a thickness A film was cast. Both surface layer polycarbonate films were peeled from the molded two-kind three-layer film on a winding line to obtain LCP extruded films for stretching of Examples 4 to 6 having a melting point of 280°C.

The obtained LCP extruded films for stretching treatment of Examples 4 to 6 were each stretched at 130°C in the TD direction at 130°C to 2.0 times (total stretch ratio: 2.0 times), and stretched at 130°C. The LCP stretched films of Examples 4 to 6 were obtained by heat setting for 30 seconds at . After that, a glass cloth (IPC No. #1037) is sandwiched between each pair of LCP stretched films of Examples 4 to 6, and a heat press is used to perform thermocompression bonding at 300 s ° C. for 5 minutes. Thus, insulating materials for circuit boards of Examples 4 to 6 were obtained.

(Comparative example 2)
Under the conditions of shear stress of 60 kPa and drawdown ratio of 6.0, a liquid crystal polymer is cast at 300° C. from a single 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. An LCP extruded film for stretching treatment of Comparative Example 2 having a melting point of 280° C. was obtained in the same manner as in Example 4 except for extrusion.

An attempt was made to obtain an LCP stretched film in the same manner as in Example 4 except that the obtained LCP extruded film for stretching treatment of Comparative Example 2 was used, but uniform stretching could not be carried out.

Table 2 shows the results.

The LCP extruded 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, IC packages, etc. Because it is highly reliable, it is widely and effectively used as an insulating material such as flexible printed circuit boards (FPC) and metal foil clad laminates in fifth-generation mobile communication systems (5G) and millimeter wave radars. It is possible.

X... Yield point strength Y... Breaking point strength 100... LCP stretched film 200... Insulating material for circuit board 300... Metal foil clad laminate 400... Metal foil clad laminate WF・・・ Woven fabric MF ・・・ Metal foil

Claims (12)

An LCP extruded film for stretch processing comprising a thermoplastic liquid crystal polymer,
Stress measured by constant temperature bath tensile test (JIS K7161-1: 2014 compliant, 200 ° C., tensile speed 200 mm / min) - In the strain curve, the yield point strength X (MPa) in the TD direction of the LCP extruded film for stretching treatment And the breaking point strength Y (MPa) is the following formula (1);
0.75≦strength at breaking point Y/strength at yield point X≦1.50 (1)
satisfy the
LCP extruded film for stretching 2. The LCP extruded film for stretching according to claim 1, wherein the LCP extruded film for stretching has a coefficient of linear expansion in the TD direction of 5 to 55 ppm/K. The LCP extruded film for stretching according to claim 1 or 2, wherein the LCP extruded film for stretching is a T-die extruded film. The LCP extruded film for stretching treatment according to any one of claims 1 to 3, wherein the LCP extruded film is an outer layer, an intermediate layer, and the intermediate layer obtained by removing the both outer layers from a laminated extruded film having the outer layer. LCP extruded film. According to any one of claims 1 to 4, the LCP extruded film for stretching treatment does not have a tape-peelable skin layer on the film surface in an adhesion test by a cross-cut method according to JIS K5600-5-6. LCP extruded film for stretch processing as described. The LCP extruded film for stretching according to any one of claims 1 to 5, wherein the LCP extruded film for stretching has a thickness of 15 µm or more and 300 µm or less. The LCP extruded film for stretching according to any one of claims 1 to 6, further comprising an inorganic filler. A stretched body of the LCP extruded film for stretching treatment according to any one of claims 1 to 7,
The linear expansion coefficient in the TD direction of the elongated body is in the range of -20 ppm/K or more and less than 0 ppm/K,
The linear expansion coefficient in the MD direction of the elongated body is in the range of -20 ppm/K or more and less than 0 ppm/K.
Heat-shrinkable LCP stretched film. 9. The stretched heat-shrinkable LCP film according to claim 8, wherein the stretched body has a stretch ratio of 1.3 to 2.5 times in the TD direction with respect to the LCP extruded film for stretching treatment. A laminate comprising at least the heat-shrinkable LCP stretched film according to claim 8 or 9 and a woven fabric provided on at least one surface of the heat-shrinkable LCP stretched film,
Insulating material for circuit boards. The heat-shrinkable LCP stretched film according to claim 8 or 9 and a metal foil provided on one side and/or both sides of the heat-shrinkable LCP stretched film,
Metal foil clad laminate. A laminate having at least the heat-shrinkable LCP stretched film and the woven fabric according to claim 8 or 9, and a metal foil provided on one side and / or both sides of the laminate,
Metal foil clad laminate.

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