JP2023034967A - Film, production method thereof, laminate film, and laminate article - Google Patents

Abstract

To provide a film excellent in peel strength from a metal substrate with an in-between adhesive layer, a production method thereof, a laminate film and a laminate article made of the film.SOLUTION: There is provided a film, a production method thereof, and a laminate film and a laminate article made of the film. The film contains a liquid crystal polymer and has a difference of a contact angle with water measured by a water droplet method in the air of 25°C, 50% RH between the inside of the film and one surface of the film of 7° or more. The production method of the film includes an oxidation step for oxidizing the surface of the film that contains the liquid crystal polymer and produces the film having a difference of a contact angle with water measured by a water droplet method in the air of 25°C, 50% RH between the inside of the film and one surface of the film of 7° or more.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present disclosure relates to films and methods of manufacturing the same, laminated films, and laminates.

In recent years, the frequency used in communication equipment tends to be very high. In order to suppress transmission loss in a high frequency band, it is required to lower the dielectric constant and dielectric loss tangent of insulating materials used for circuit boards.

As a conventional method for manufacturing a liquid crystal film, for example, the method described in Patent Document 1 is known.
Patent Literature 1 describes a method for modifying the surface of an article made of a liquid crystal polymer material, which includes irradiating the surface of the article made of a liquid crystal polymer material with ions.

JP 2008-308616 A

The problem to be solved by the embodiments of the present invention is to provide a film excellent in peel strength from a metal substrate via an adhesive layer, and a method for producing the same.
Another problem to be solved by another embodiment of the present invention is to provide a laminate film and a laminate using the above film.

Means for solving the above problems include the following aspects.
<1> A film containing a liquid crystal polymer and having a difference of 7° or more between the inside of the film and one surface of the film in contact angle with water measured by the water droplet method at 25° C. and 50% RH.
<2> The film according to <1>, wherein one surface of the film has a surface free energy of 47 N/m to 60 N/m.
<3> The film according to <1> or <2>, wherein the contact angle with water on one surface of the film is 50° or more and less than 75° by the water droplet method at 25°C and 50% RH.
<4> The difference between the contact angle with water measured by the water droplet method at 25° C. and 50% RH between the inside of the film and one surface of the film is 7° or more and 32° or less <1> to <3. The film according to any one of >.
<5> The film according to any one of <1> to <4>, wherein one surface of the film has a surface roughness Ra of 0.05 μm or less.
<6> The liquid crystal polymer has at least one structural unit selected from the group consisting of structural units derived from parahydroxybenzoic acid and structural units derived from 6-hydroxy-2-naphthoic acid. The film according to any one of <1> to <5>.
<7> The liquid crystal polymer contains structural units derived from 6-hydroxy-2-naphthoic acid, structural units derived from an aromatic diol compound, structural units derived from terephthalic acid, and 2,6-naphthalenedicarboxylic acid. The film according to any one of <1> to <5>, comprising a liquid crystal polymer having at least one structural unit selected from the group consisting of structural units derived from the liquid crystal polymer.
<8> The film according to any one of <1> to <7>, further comprising polyolefin.
<9> The film according to <8>, wherein the content of the polyolefin is 0.1% by mass to 40% by mass with respect to the total mass of the film.
<10> The film according to <8> or <9>, wherein the polyolefin forms a dispersed phase in the film.
<11> The film according to <10>, wherein the dispersed phase has an average dispersed diameter of 0.01 μm to 10 μm.
<12> The film according to any one of <1> to <11>, wherein one surface of the film has an elastic modulus at 240° C. of 300 MPa or more.
<13> A laminated film having a layer A and a layer B on at least one surface of the layer A, wherein the layer A is the film according to any one of <1> to <12>.
<14> The laminated film according to <13>, wherein the layer B has an elastic modulus at 140° C. of 0.1 MPa or less.
<15> A metal substrate is provided on one surface of the film according to any one of <1> to <12> or on the layer B side surface of the laminated film according to <13> or <14>. laminate.
<16> A compound having a functional group on one surface of the film according to any one of <1> to <12> or on either surface of the laminated film according to <13> or <14> and a metal substrate, wherein the functional group is an epoxy group, an oxetanyl group, an isocyanate group, an acid anhydride group, a carbodiimide group, an N-hydroxyester group, a glyoxal group, an imidoester group, a halogenated A laminate containing at least one of an alkyl group and a thiol group.
<17> The laminate according to <15> or <16>, wherein the maximum height Rz of the film-side surface of the metal substrate is 2.0 μm or less.
<18> Including an oxidation treatment step of oxidizing the surface of the film containing the liquid crystal polymer, in the produced film, the contact angle with water by the water droplet method at 25 ° C. 50% RH, the inside of the film and one of the film A method for producing a film having a difference of 7° or more from the surface of
<19> According to <18>, having an oxidation treatment step in which the contact angle with water on one surface of the produced film is 50 ° or more and less than 75 ° by the water droplet method at 25 ° C. 50% RH. Film production method.
<20> The method for producing a film according to <18> or <19>, wherein the oxidation treatment step is a step of contacting the surface of the film with an oxidizing agent in an aqueous solution.
<21> The method for producing a film according to <20>, wherein the oxidizing agent has a standard oxidation-reduction potential of 1.5 V or more.
<22> The oxidizing agent is sodium persulfate, potassium persulfate, ammonium persulfate, hydrogen peroxide, potassium permanganate, sodium hypochlorite, ammonium cerium nitrate, potassium chromate, potassium dichromate, and peroxyl The method for producing a film according to <20> or <21>, which contains at least one compound selected from the group consisting of double salts consisting of potassium sulfate, potassium hydrogensulfate and potassium sulfate.
<23> The method for producing a film according to any one of <20> to <22>, wherein the aqueous solution has a pH of 12 or more.

ADVANTAGE OF THE INVENTION According to the embodiment of this invention, the film which is excellent in the peeling strength with the metal substrate through an adhesive layer, and its manufacturing method can be provided.
Further, according to another embodiment of the present invention, it is possible to provide a laminate film and a laminate using the above film.

The content of the present disclosure will be described in detail below. The description of the constituent elements described below may be made based on representative embodiments of the present disclosure, but the present disclosure is not limited to such embodiments.
In this specification, the term "to" indicating a numerical range is used to include the numerical values before and after it as lower and upper limits.
In the numerical ranges described step by step in the present disclosure, the upper limit or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described step by step. . Moreover, in the numerical ranges described in the present disclosure, the upper or lower limits of the numerical ranges may be replaced with the values shown in the examples.
In addition, in the description of groups (atomic groups) in the present specification, the descriptions that do not indicate substitution or unsubstituted include those having no substituents as well as those having substituents. For example, the term “alkyl group” includes not only alkyl groups having no substituents (unsubstituted alkyl groups) but also alkyl groups having substituents (substituted alkyl groups).
In the present specification, "(meth)acrylic" is a term used as a concept that includes both acrylic and methacrylic, and "(meth)acryloyl" is a term that is used as a concept that includes both acryloyl and methacryloyl. is.
In addition, the term "step" in this specification is not only an independent step, but even if it cannot be clearly distinguished from other steps, if the intended purpose of the step is achieved included. In addition, in the present disclosure, "% by mass" and "% by weight" are synonymous, and "parts by mass" and "parts by weight" are synonymous.
Furthermore, in the present disclosure, a combination of two or more preferred aspects is a more preferred aspect.
In addition, unless otherwise specified, the weight average molecular weight (Mw) and number average molecular weight (Mn) in the present disclosure are measured by gel permeation chromatography using a TSKgel SuperHM-H (trade name of Tosoh Corporation) column ( GPC) analyzer, solvent PFP (pentafluorophenol)/chloroform = 1/2 (mass ratio), detection with a differential refractometer, molecular weight converted using polystyrene as a standard substance.

(the film)
The film according to the present disclosure contains a liquid crystal polymer, and the difference in contact angle with water between the inside of the film and one surface of the film by the water droplet method at 25° C. and 50% RH is 7° or more.

A film containing a conventional liquid crystal polymer sometimes has a problem of peel strength from a metal substrate via an adhesive layer.
The film according to the present disclosure has a difference of 7° or more between the inside of the film and one surface of the film in the contact angle with water measured by the water-in-air method at 25°C and 50% RH. Since the surface becomes more hydrophilic and the adhesion between the surface and the adhesive layer containing epoxy resin or the like is improved, it is possible to provide a film having excellent peel strength from the metal substrate via the adhesive layer.
In addition, the film according to the present disclosure is excellent in peel strength from the metal substrate via the adhesive layer even after wet heat aging due to the above aspect.

<Difference in contact angle with water between the inside of the film and one surface of the film>
In the film according to the present disclosure, the difference in the contact angle with water measured by the water droplet method at 25 ° C. and 50% RH between the inside of the film and one surface of the film is 7 ° or more, and the contact angle is 7 ° or more. Improvement of the peel strength with the metal substrate (hereinafter also simply referred to as "peel strength"), and improvement of the peel strength with the metal substrate via the adhesive layer after wet heat aging (hereinafter, "peeling strength after wet heat aging" ), the angle is preferably 7° or more and 32° or less, more preferably 10° or more and 30° or less, and particularly preferably 20° or more and 28° or less.
Further, in the film according to the present disclosure, one surface of the film that satisfies the range of the difference in contact angle of water is the surface that contacts the adhesive layer, that is, the surface that is bonded to the metal substrate via the adhesive layer. is preferred.

The value of the contact angle with water on one surface of the film is preferably smaller than the value of the contact angle with water inside the film, from the viewpoint of peel strength and peel strength after wet heat aging. .
In addition, the value of the contact angle with water on one surface of the film is preferably 50° or more and less than 75°, from the viewpoint of peel strength and peel strength after wet heat aging, and 55° or more and 73°. or less, and particularly preferably 60° or more and 70° or less.
The value of the contact angle with the water inside the film is preferably 75° or more and 100° or less, and 80° or more and 90° or less, from the viewpoint of peel strength and peel strength after wet heat aging. is more preferred.

In the present disclosure, the measurement of the water contact angle of the film surface at 25° C. and 50% RH by the water drop method in air is performed by the following method.
The contact angle of water on one surface of the film is measured at 25° C. and 50% RH. A contact angle meter (DM700) manufactured by Kyowa Interface Science Co., Ltd. is used for the measurement. The contact angle is calculated by averaging 10 points by reading the value of the contact angle 5 seconds after the droplet is prepared.

In the present disclosure, the measurement of the water contact angle inside the film at 25° C. and 50% RH by the water drop method in air is performed by the following method.
After the film is melted by heating above the melting point of the liquid crystal polymer contained in the film, it is molded into a film again. It is considered that the original surface and the inside of the molded film are completely mixed up because the molded film has been heated above the melting point once. The water contact angle on one surface of the film thus obtained is measured in the same manner as above, and the value is defined as the water contact angle inside the film.

<Surface free energy>
The surface free energy on one surface of the film is preferably 46 N/m to 65 N/m, more preferably 47 N/m to 60 N/m, from the viewpoint of peel strength and peel strength after wet heat aging. More preferably, it is particularly preferably 49 N/m to 60 N/m.
Further, in the film according to the present disclosure, one surface of the film that satisfies the range of surface free energy is a surface that forms an adhesive layer, that is, a surface that forms an adhesive layer and is attached to a metal substrate. preferable.

The method for measuring the surface free energy of the film surface in the present disclosure is as follows.
Based on the method by Owens, using water and methylene iodide with known surface free energy, water is dropped on the film surface to determine the contact angle of water, and methylene iodide is dropped on the film surface to determine the contact angle of methylene iodide. Each contact angle is measured and the surface free energy (N/m) is calculated. The method for measuring each contact angle is the same as the method for measuring the water contact angle on the film surface.

<Surface roughness Ra>
In the film according to the present disclosure, the surface roughness Ra on one surface of the film is preferably 0.05 μm or less, more preferably 0.03 μm or less, and particularly 0.025 μm or less. preferable. The lower limit is preferably 0.001 μm or more, more preferably 0.005 μm or more, and particularly preferably 0.010 μm or more.

The surface roughness Ra in the present disclosure is calculated using a surface roughness meter. It is calculated based on the calculation method of the average roughness Ra.

<Dielectric loss tangent>
The dielectric loss tangent of the film according to the present disclosure is preferably 0.01 or less, and preferably 0.005 or less, from the viewpoint of suppressing breakage failure during peeling and reducing transmission loss of the manufactured substrate. It is more preferably 0.004 or less, and particularly preferably more than 0 and 0.003 or less.

A method for measuring the dielectric loss tangent of a film or polymer in the present disclosure is as follows.
A dielectric loss tangent is measured by a resonance perturbation method at a frequency of 10 GHz. A 10 GHz cavity resonator (Kanto Electronics Applied Development Co., Ltd. CP531) was connected to a network analyzer ("E8363B" manufactured by Agilent Technology), and a film sample (width: 2.0 mm x length: 80 mm) was connected to the cavity resonator. The film is inserted, and the dielectric loss tangent of the film is measured from the change in resonance frequency before and after the insertion for 96 hours under an environment of temperature 25° C. and humidity 60% RH.

<Liquid crystal polymer>
A film according to the present disclosure comprises a liquid crystal polymer.
The liquid crystal polymer may be a thermotropic liquid crystal polymer that exhibits liquid crystallinity in a molten state, or a lyotropic liquid crystal polymer that exhibits liquid crystallinity in a solution state. In the case of thermotropic liquid crystal, it is preferable that it melts at a temperature of 450° C. or less.
Examples of liquid crystalline polymers include liquid crystalline polyesters, liquid crystalline polyester amides in which amide bonds are introduced into liquid crystalline polyesters, liquid crystalline polyester ethers in which ether bonds are introduced into liquid crystalline polyesters, and liquid crystalline polyester carbonates in which carbonate bonds are introduced into liquid crystalline polyesters. can be mentioned.
From the viewpoint of liquid crystallinity and linear expansion coefficient, the liquid crystal polymer is preferably a polymer having an aromatic ring, more preferably an aromatic polyester or an aromatic polyesteramide.
Further, the liquid crystal polymer may be a polymer obtained by introducing an isocyanate-derived bond such as an imide bond, a carbodiimide bond, or an isocyanurate bond into an aromatic polyester or an aromatic polyesteramide.
Further, the liquid crystal polymer is preferably a wholly aromatic liquid crystal polymer using only aromatic compounds as raw material monomers.

Examples of liquid crystal polymers include, for example:
1) (i) an aromatic hydroxycarboxylic acid, (ii) an aromatic dicarboxylic acid, and (iii) at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxylamine and an aromatic diamine; A product obtained by polycondensation.
2) Those obtained by polycondensing a plurality of types of aromatic hydroxycarboxylic acids.
3) Polycondensation of (i) an aromatic dicarboxylic acid and (ii) at least one compound selected from the group consisting of aromatic diols, aromatic hydroxylamines and aromatic diamines.
4) Polycondensation of (i) a polyester such as polyethylene terephthalate and (ii) an aromatic hydroxycarboxylic acid.
Here, aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, aromatic diols, aromatic hydroxyamines and aromatic diamines are each independently used in place of part or all of their polycondensable derivatives. good too.

Examples of polymerizable derivatives of compounds having a carboxy group such as aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids include those obtained by converting the carboxy group to an alkoxycarbonyl group or an aryloxycarbonyl group (ester), carboxy Examples thereof include those obtained by converting a group to a haloformyl group (acid halides) and those obtained by converting a carboxy group to an acyloxycarbonyl group (acid anhydrides).
Examples of polymerizable derivatives of compounds having a hydroxy group such as aromatic hydroxycarboxylic acids, aromatic diols and aromatic hydroxyamines include those obtained by acylating the hydroxy group to convert it to an acyloxy group (acylated product). is mentioned.
Examples of polymerizable derivatives of compounds having an amino group such as aromatic hydroxylamines and aromatic diamines include those obtained by acylating the amino group to convert it to an acylamino group (acylated product).

From the viewpoint of liquid crystallinity, dielectric loss tangent of the film, and adhesion to the metal substrate, the liquid crystal polymer is a structural repeating unit represented by any of the following formulas (1) to (3) (hereinafter, formula (1 ) is sometimes referred to as a repeating unit (1), etc.), more preferably has a constituent repeating unit represented by the following formula (1), and the following formula It is particularly preferable to have a structural repeating unit represented by (1), a structural repeating unit represented by the following formula (2), and a structural repeating unit represented by the following formula (2).
Formula (1) —O—Ar ¹ —CO—
Formula (2) —CO—Ar ² —CO—
Formula (3) -X-Ar ³ -Y-
In formulas (1) to (3), Ar ¹ represents a phenylene group, naphthylene group or biphenylylene group, and Ar ² and Ar ³ each independently represent a phenylene group, naphthylene group, biphenylylene group or the following formula (4) represents a group represented by X and Y each independently represents an oxygen atom or an imino group, and hydrogen atoms in the groups represented by Ar ¹ to Ar ³ each independently represent a halogen atom, an alkyl group Alternatively, it may be substituted with an aryl group.
Formula (4) -Ar ⁴ -Z-Ar ⁵ -
In formula (4), Ar ⁴ and Ar ⁵ each independently represent a phenylene group or a naphthylene group, and Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylene group.

The halogen atoms include fluorine, chlorine, bromine and iodine atoms.
Examples of the above alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-hexyl group, 2-ethylhexyl group, n-octyl group and n-decyl group, preferably having 1 to 10 carbon atoms.
Examples of the aryl group include phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 1-naphthyl group and 2-naphthyl group, preferably having 6 to 20 carbon atoms. be.
When the above hydrogen atoms are substituted with these groups, the number thereof is preferably 2 or less, more preferably 1, independently for each of the above groups represented by Ar ¹ , Ar ² or Ar ³ . is one.

Examples of the alkylene group include methylene group, 1,1-ethanediyl group, 1-methyl-1,1-ethanediyl group, 1,1-butanediyl group and 2-ethyl-1,1-hexanediyl group. , preferably has 1 to 10 carbon atoms.

Repeating unit (1) is a structural repeating unit derived from a predetermined aromatic hydroxycarboxylic acid.
Examples of the repeating unit (1) include those in which Ar ¹ is a p-phenylene group (a structural repeating unit derived from p-hydroxybenzoic acid) and those in which Ar ¹ is a 2,6-naphthylene group (a 6-hydroxy -2-naphthoic acid-derived structural repeating unit) or a 4,4'-biphenylylene group (4'-hydroxy-4-biphenylcarboxylic acid-derived structural repeating unit).

Repeating unit (2) is a structural repeating unit derived from a predetermined aromatic dicarboxylic acid.
The repeating unit (2) includes those in which Ar ² is a p-phenylene group (structural repeating unit derived from terephthalic acid), those in which Ar ² is an m-phenylene group (structural repeating unit derived from isophthalic acid), Ar ² is a 2,6-naphthylene group (a structural repeating unit derived from 2,6-naphthalenedicarboxylic acid), or Ar ² is a diphenyl ether-4,4'-diyl group (diphenyl ether-4, A structural repeating unit derived from 4'-dicarboxylic acid) is preferred.

Repeating unit (3) is a structural repeating unit derived from a predetermined aromatic diol, aromatic hydroxylamine or aromatic diamine.
Examples of the repeating unit (3) include those in which Ar ³ is a p-phenylene group (structural repeating units derived from hydroquinone, p-aminophenol or p-phenylenediamine), those in which Ar ³ is an m-phenylene group (isophthalene structural repeating unit derived from an acid), or those in which Ar ³ is a 4,4'-biphenylylene group (4,4'-dihydroxybiphenyl, 4-amino-4'-hydroxybiphenyl or 4,4'-diaminobiphenyl Structural repeating units derived from) are preferred.

The content of the repeating unit (1) is the total amount of all constituent repeating units (the mass of each constituent repeating unit constituting the liquid crystal polymer is divided by the formula weight of each repeating unit, and the amount equivalent to the substance amount of each repeating unit (mole) is calculated and the total value) is preferably 30 mol% or more, more preferably 30 mol% to 80 mol%, still more preferably 30 mol% to 60 mol%, particularly preferably 30 mol % to 40 mol %.
The content of the repeating unit (2) is preferably 35 mol% or less, more preferably 10 mol% to 35 mol%, still more preferably 20 mol% to 35 mol%, based on the total amount of all constituent repeating units, Particularly preferably, it is 30 mol % to 35 mol %.
The content of the repeating unit (3) is preferably 35 mol% or less, more preferably 10 mol% to 35 mol%, still more preferably 20 mol% to 35 mol%, based on the total amount of all constituent repeating units, Particularly preferably, it is 30 mol % to 35 mol %.
The higher the content of the repeating unit (1), the more likely the heat resistance, strength and rigidity are improved.

The ratio between the content of the repeating unit (2) and the content of the repeating unit (3) is expressed as [content of the repeating unit (2)]/[content of the repeating unit (3)] (mol/mol). , preferably 0.9/1 to 1/0.9, more preferably 0.95/1 to 1/0.95, still more preferably 0.98/1 to 1/0.98.

The liquid crystal polymer may have two or more types of repeating units (1) to (3) independently. In addition, the liquid crystal polymer may have constituent repeating units other than the repeating units (1) to (3), but the content thereof is preferably 10 mol% or less with respect to the total amount of all repeating units. More preferably, it is 5 mol % or less.

The liquid crystal polymer has, as repeating units (3), at least one of X and Y being an imino group, i.e., a structural repeating unit derived from a predetermined aromatic hydroxylamine and a structural repeating unit derived from an aromatic diamine. It is preferable to have at least one of the units because the solubility in a solvent is excellent, and it is more preferable to have only repeating units (3) in which at least one of X and Y is an imino group.

Among them, from the viewpoint of dispersibility and tensile strength, the liquid crystal polymer contains at least a structural unit derived from parahydroxybenzoic acid and a structural unit derived from 6-hydroxy-2-naphthoic acid. It preferably contains a liquid crystal polymer having one type of structural unit, and more preferably contains a liquid crystal polymer having a structural unit derived from parahydroxybenzoic acid and a structural unit derived from 6-hydroxy-2-naphthoic acid. .
In addition, from the viewpoint of dispersibility and tensile strength, the liquid crystal polymer has a structural unit derived from 6-hydroxy-2-naphthoic acid, a structural unit derived from an aromatic diol compound, a structural unit derived from terephthalic acid, and , It preferably contains a liquid crystal polymer having at least one structural unit selected from the group consisting of structural units derived from 2,6-naphthalenedicarboxylic acid, a structural unit derived from 6-hydroxy-2-naphthoic acid, More preferably, it contains a liquid crystal polymer having structural units derived from an aromatic diol compound, structural units derived from terephthalic acid, and structural units derived from 2,6-naphthalenedicarboxylic acid.

The liquid crystal polymer is preferably produced by melt-polymerizing raw material monomers corresponding to the constituent repeating units constituting the liquid crystal polymer. The melt polymerization may be carried out in the presence of a catalyst, examples of which include metal compounds such as magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, antimony trioxide, Nitrogen-containing heterocyclic compounds such as 4-(dimethylamino)pyridine and 1-methylimidazole are included, and nitrogen-containing heterocyclic compounds are preferably used. In addition, the melt polymerization may be further subjected to solid phase polymerization, if necessary.

The liquid crystal polymer has a flow initiation temperature of preferably 250° C. or higher, more preferably 250° C. or higher and 350° C. or lower, and still more preferably 260° C. or higher and 330° C. or lower. When the flow initiation temperature of the liquid crystal polymer is within the above range, the solubility, heat resistance, strength and rigidity are excellent, and the viscosity of the solution is moderate.

The flow initiation temperature is also called flow temperature or flow temperature, and melts the liquid crystal polymer while increasing the temperature at a rate of 4 ° C./min under a load of 9.8 MPa (100 kg/cm ² ) using a capillary rheometer. It is the temperature at which a viscosity of 4,800 Pa s (48,000 poise) is exhibited when extruded from a nozzle with an inner diameter of 1 mm and a length of 10 mm. , "Liquid Crystal Polymer -Synthesis/Molding/Application-", CMC Co., Ltd., June 5, 1987, p.95).

The liquid crystal polymer preferably has a weight average molecular weight of 1,000,000 or less, more preferably 3,000 to 300,000, and even more preferably 5,000 to 100,000. , 5,000 to 30,000 are particularly preferred. When the weight average molecular weight of the liquid crystal polymer is within the above range, the heat-treated film is excellent in thermal conductivity, heat resistance, strength and rigidity in the thickness direction.

The liquid crystal polymer is preferably a polymer soluble in a specific organic solvent (hereinafter also referred to as "soluble polymer").
Specifically, the soluble polymers in the present disclosure are N-methylpyrrolidone, N-ethylpyrrolidone, dichloromethane, dichloroethane, chloroform, N,N-dimethylacetamide, γ-butyrolactone, dimethylformamide, ethylene glycol monobutyl ether at 25°C. and ethylene glycol monoethyl ether.

A film according to the present disclosure may contain only one type of liquid crystal polymer, or may contain two or more types.
The content of the liquid crystal polymer in the film according to the present disclosure is preferably 20% by mass to 100% by mass with respect to the total mass of the film from the viewpoint of dielectric loss tangent of the film and adhesion to the metal substrate. , more preferably 30% by mass to 100% by mass, and particularly preferably 40% by mass to 100% by mass.

<Polyolefin>
The film according to the present disclosure preferably further contains polyolefin from the viewpoint of peel strength and peel strength after wet heat aging.
The polyolefin is not particularly limited, but is preferably poly-α-olefin, more preferably polyethylene or polypropylene.

When the film contains polyolefin, from the viewpoint of peel strength and peel strength after wet heat aging, it is preferable that the polyolefin forms a dispersed phase in the film, the polyolefin is an island structure, and the liquid crystal polymer is a sea. It is more preferable to have a sea-island structure.
The average dispersed diameter of the dispersed phase is preferably 0.01 μm to 20 μm, more preferably 0.01 μm to 10 μm, from the viewpoint of peel strength and peel strength after wet heat aging.
The method for measuring the average dispersed diameter of the dispersed phase is to observe the cross section of the film, measure the maximum diameter of 10 dispersed phases in descending order, and take the average.

The film according to the present disclosure may contain one type of polyolefin alone, or may contain two or more types.
The content of the polyolefin is preferably 0.1% by mass to 40% by mass, and preferably 1% by mass to 30% by mass, based on the total mass of the film, from the viewpoint of peel strength and peel strength after wet heat aging. % by mass is more preferred.

<Filler>
The film according to the present disclosure preferably contains a filler from the viewpoint of dielectric properties, coefficient of thermal expansion, and adhesion to metal substrates.
The filler may be particulate or fibrous, and may be an inorganic filler or an organic filler.
In the film according to the present disclosure, the number density of the filler is preferably higher inside the film than on the surface, from the viewpoint of dielectric properties, coefficient of thermal expansion, and adhesion to the metal substrate.

A known inorganic filler can be used as the inorganic filler.
Examples of inorganic filler materials include BN, Al ₂ O ₃ , AlN, TiO ₂ , SiO ₂ , barium titanate, strontium titanate, aluminum hydroxide, calcium carbonate, and materials containing two or more of these. be done.
Among them, from the viewpoint of adhesion to the metal substrate, the inorganic filler is preferably metal oxide particles or fibers, more preferably silica particles, titania particles or glass fibers, and silica particles or glass fibers. Especially preferred.
The average particle size of the inorganic filler is not particularly limited, but is preferably about 20% to about 40% of the thickness of the layer containing the filler, for example, 25%, 30% or 30% of the thickness of the layer containing the filler. The one at 35% may be selected. When the particles or fibers are flattened, the length in the short side direction is indicated.
Further, the average particle size of the inorganic filler is preferably 5 nm to 20 μm, more preferably 10 nm to 10 μm, even more preferably 20 nm to 1 μm, and 25 nm, from the viewpoint of adhesion to the metal substrate. ~500 nm is particularly preferred.

A well-known organic filler can be used as an organic filler.
Examples of the material of the organic filler include polyethylene, polystyrene, urea-formalin filler, polyester, cellulose, acrylic resin, fluorine resin, cured epoxy resin, crosslinked benzoguanamine resin, crosslinked acrylic resin, crosslinked styrene, and two or more of these. material containing.
Further, the organic filler may be fibrous such as nanofibers, or may be hollow resin particles.
Among them, the organic filler is preferably fluororesin particles, polyester resin particles, or cellulose resin nanofibers from the viewpoint of adhesion to the metal substrate, and polytetrafluoroethylene particles. is more preferred.
The average particle size of the organic filler is preferably 5 nm to 20 μm, more preferably 10 nm to 1 μm, even more preferably 20 nm to 500 nm, further preferably 25 nm to 90 nm, from the viewpoint of adhesion to the metal substrate. is particularly preferred.

The film according to the present disclosure may contain only one type of filler, or may contain two or more types.
The content of the filler in the film according to the present disclosure is preferably 5% by mass to 80% by mass, based on the total volume of the film, from the viewpoint of the coefficient of thermal expansion and adhesion to the metal substrate, and 10% by mass. % to 70% by mass, more preferably 20% to 70% by mass, and particularly preferably 25% to 60% by mass.

-Other additives-
Films according to the present disclosure may contain other additives.
As other additives, known additives can be used. Specific examples include leveling agents, antifoaming agents, antioxidants, ultraviolet absorbers, flame retardants, colorants and the like.

Moreover, as other additives, resins other than the components described above may be included.
Examples of resins other than those mentioned above include thermoplastic resins such as cycloolefin polymers, polyamides, polyesters, polyphenylene sulfides, polyetherketones, polycarbonates, polyethersulfones, polyphenylene ethers and modified products thereof, and polyetherimides; Elastomers such as copolymers with polyethylene; and thermosetting resins such as phenol resins, epoxy resins, polyimide resins and cyanate resins.

The total content of other additives is preferably 25 parts by mass or less, more preferably 10 parts by mass or less, and still more preferably 5 parts by mass or less with respect to 100 parts by mass of the polymer content.

<Thermal expansion coefficient>
From the viewpoint of thermal stability, the thermal expansion coefficient of the film according to the present disclosure is preferably −20 ppm/K to 50 ppm/K, more preferably −10 ppm/K to 40 ppm/K, and 0 ppm/K. ~35 ppm/K is more preferred, and 10 ppm/K to 30 ppm/K is particularly preferred.

The method for measuring the coefficient of thermal expansion in the present disclosure shall be measured by the following method.
Using a thermomechanical analyzer (TMA), a tensile load of 1 g was applied to both ends of a film with a width of 5 mm and a length of 20 mm, and the temperature was raised from 25 ° C. to 200 ° C. at a rate of 5 ° C./min, and then 2 ° C./ The thermal expansion coefficient is calculated from the slope of the TMA curve between 30° C. and 150° C. when the temperature is cooled to 30° C. at a rate of 5° C./min and the temperature is again raised at a rate of 5° C./min. The copper foil is removed with ferric chloride before measurement.

<Elastic modulus>
The elastic modulus of one surface of the film according to the present disclosure at 240° C. is preferably 100 MPa or more, more preferably 300 MPa or more, from the viewpoint of mechanical strength and prevention of breakage failure during peeling.
In addition, the elastic modulus at 25° C. of one surface of the film according to the present disclosure is preferably 100 MPa or more from the viewpoint of mechanical strength and prevention of breakage failure during peeling.
In addition, the surface satisfying the range of elastic modulus may be a surface satisfying the range of difference in water contact angle, a surface satisfying the range of surface free energy, or a surface satisfying the range of surface roughness Ra. preferable.

In the present disclosure, the elastic modulus of the film surface shall be measured by the following method.
The elastic modulus of the film surface is determined using a microsurface hardness tester (“Fisherscope H100VP-HCU” manufactured by Fisher Instruments Co., Ltd.). Specifically, using a diamond square pyramid indenter (tip facing angle: 136 °), the indentation depth under an appropriate test load is set to 240 ° C. or 25 ° C. , and the storage modulus is calculated from the change in load and displacement when the load is unloaded.

A film according to the present disclosure may have a single-layer structure or a multi-layer structure.

The average thickness of the film according to the present disclosure is preferably 6 μm to 200 μm, more preferably 12 μm to 100 μm, from the viewpoint of strength, coefficient of thermal expansion, and adhesion to metal foil or metal wiring. 20 μm to 60 μm is particularly preferred.

The average thickness of the polymer film is measured at any five locations using an adhesive film thickness gauge, for example, an electronic micrometer (product name “KG3001A”, manufactured by Anritsu Corporation), and the average value thereof is taken.

<Application>
The film according to the present disclosure can be used for various purposes, and among others, it can be suitably used as a film for electronic parts such as printed wiring boards, and more suitably used as a flexible printed circuit board.
Moreover, the film according to the present disclosure can be suitably used as a metal adhesion film.

(Film manufacturing method)
A method for producing a film according to the present disclosure includes an oxidation treatment step of oxidizing the surface of a film containing a liquid crystal polymer, and in the produced film, the contact angle with water by the water drop method at 25 ° C. 50% RH The difference between the inside of the produced film and one surface of the produced film is 7° or more.
The film according to the present disclosure is preferably a film produced by the method for producing a film according to the present disclosure.

In the method for producing a film according to the present disclosure, the above-described components among the components used, and the preferred aspects of each component and content contained in the resulting film are the above-described preferred aspects of the film according to the present disclosure. It is the same.
In addition, in the method for producing a film according to the present disclosure, the amount of each component used is the same as the preferred amount corresponding to the preferable aspect of the content of each component in the film according to the present disclosure.
In the method for producing a film according to the present disclosure, each preferred physical property value of the produced film is the same as the preferred embodiment of the film according to the present disclosure described above.

<Oxidation treatment process>
The method for producing a film according to the present disclosure preferably includes an oxidation treatment step of oxidizing the surface of the film containing the liquid crystal polymer.
The oxidation treatment step is preferably a step of oxidizing the surface of the film using an oxidizing agent, and the surface of the film is brought into contact with the oxidizing agent in an aqueous solution to oxidize at least one surface of the film. It is more preferable to be a step of allowing
Moreover, it is preferable to oxidize both sides of the film containing the liquid crystal polymer.
The pH of the aqueous solution is not particularly limited as long as it can be oxidized, but is preferably 8 or higher, more preferably 12 or higher, and even more preferably 13 or higher.
The upper limit of the pH of the aqueous solution is not limited, and is 14, for example.

The time for contacting the surface of the film with the oxidizing agent in the aqueous solution is preferably 1 minute to 24 hours, more preferably 3 minutes to 5 hours, and even more preferably 5 minutes to 3 hours.
The temperature of the aqueous solution when the surface of the film is brought into contact with the oxidizing agent is preferably 1°C to 95°C, more preferably 25°C to 80°C, and even more preferably 45°C to 65°C.

The method of bringing the surface of the film into contact with the oxidizing agent in the above aqueous solution is not particularly limited, and examples thereof include a method of immersing the film in the oxidizing agent aqueous solution.

After bringing the surface of the film into contact with the oxidizing agent in the aqueous solution, it is preferable to remove the obtained film from the aqueous solution.
It is also preferable to wash the obtained film with water, an organic solvent, or the like.

-Oxidant-
It is preferable to use an oxidizing agent in the oxidation treatment step.
The aqueous solution preferably contains an oxidizing agent.
The oxidizing agent is without limitation, for example persulfates such as sodium persulfate, potassium persulfate and ammonium persulfate; nitrates such as ceric ammonium nitrate, sodium nitrate and ammonium nitrate; hydrogen peroxide and Manganese compounds such as potassium permanganate and manganese dioxide; Chromium compounds such as potassium chromate and potassium dichromate; Potassium periodate and periodic acid. hypervalent iodine compounds such as sodium; quinone compounds such as p-benzoquinone, 1,2-naphthoquinone, anthraquinone and chloranil; amine oxide compounds such as N-methylmorpholine N-oxide, sodium hypochlorite , salts of halogen oxoacids such as sodium chlorite, and double salts composed of potassium peroxymonosulfate, potassium hydrogensulfate and potassium sulfate (OXONE manufactured by DuPont).
Among them, the oxidizing agent preferably contains a persulfate, more preferably a persulfate, from the viewpoint of oxidizing property, dispersibility and tensile strength.
As the oxidizing agent, sodium persulfate, potassium persulfate, ammonium persulfate, hydrogen peroxide, potassium permanganate, sodium hypochlorite, ammonium cerium nitrate, potassium chromate, potassium dichromate, from the viewpoint of oxidation. , and preferably contains at least one compound selected from the group consisting of double salts consisting of potassium peroxymonosulfate, potassium hydrogensulfate and potassium sulfate, sodium persulfate, potassium persulfate, ammonium persulfate, hydrogen peroxide, It is more preferable to contain at least one compound selected from the group consisting of sodium hypochlorite, ammonium cerium nitrate, and a double salt consisting of potassium peroxymonosulfate, potassium hydrogensulfate, and potassium sulfate, sodium persulfate, persulfate It is particularly preferable to contain at least one compound selected from the group consisting of potassium and ammonium persulfate.

In addition, a catalyst may be used separately from the oxidant to assist the action of the oxidant. Examples of the catalyst include divalent iron compounds (such as FeSO ₄ ) and trivalent iron compounds.
Note that the oxidizing agent and the catalyst may each be a hydrate.

In addition, the standard oxidation-reduction potential of the oxidizing agent is preferably 0.30 V or higher, more preferably 1.50 V or higher, and even more preferably 1.70 or higher, from the viewpoint of oxidizing properties. The upper limit of the standard oxidation-reduction potential of the oxidizing agent is not particularly limited. For example, it is preferably 4.00 V or less, more preferably 2.50 V or less.
The above standard oxidation-reduction potential is based on a standard hydrogen electrode.

The content of the oxidizing agent in the aqueous solution is preferably 0.05 parts by mass to 20 parts by mass, more preferably 0.1 part by mass to 20 parts by mass, and 1 part by mass with respect to 100 parts by mass of water in the aqueous solution. ~20 parts by weight is particularly preferred.
The oxidizing agents may be used singly or in combination of two or more.
When the aqueous solution contains a catalyst, the content of the oxidizing agent is preferably 0.005 parts by mass to 20 parts by mass, more preferably 0.01 parts by mass to 10 parts by mass, relative to 100 parts by mass of water in the aqueous solution. Preferably, 0.1 to 2 parts by mass is more preferable.
A catalyst may be used individually by 1 type, and may use 2 or more types.

-Alkaline compound-
In order to adjust the pH of the aqueous solution, the aqueous solution preferably contains an alkaline compound in addition to the components described above.
Examples of the alkaline compound include inorganic bases such as alkali metal hydroxides (sodium hydroxide, etc.) and alkaline earth metal hydroxides; and organic bases. Among them, alkali metal hydroxides are preferred.
The content of the alkaline compound in the aqueous solution may be adjusted as appropriate so that the pH of the aqueous solution can be adjusted to a desired temperature. Parts by mass are preferred.

<Formation process>
A method for producing a film according to the present disclosure preferably includes a forming step of applying a composition containing a liquid crystal polymer and a solvent onto a substrate and drying the composition to form a film.
The method for forming the film into a shape is not particularly limited, and known methods can be referred to. Preferred examples include casting, coating, extrusion, and the like, and casting is particularly preferred. preferable. Moreover, when the film has a multilayer structure, for example, a co-casting method, a multi-layer coating method, a co-extrusion method, and the like can be preferably used. Among them, the co-casting method is particularly preferable for forming a relatively thin film, and the co-extrusion method is particularly preferable for forming a thick film.
When a multilayer structure in a film is produced by a co-casting method and a multi-layer coating method, a layer A-forming composition, a layer B-forming composition, etc. in which each layer component such as a liquid crystal polymer is dissolved or dispersed in a solvent is used. , a co-casting method or a multi-layer coating method is preferably performed.

Examples of solvents include halogenated hydrocarbons such as dichloromethane, chloroform, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, 1-chlorobutane, chlorobenzene and o-dichlorobenzene; Halogenated phenols such as p-chlorophenol, pentachlorophenol, pentafluorophenol; ethers such as diethyl ether, tetrahydrofuran, 1,4-dioxane; ketones such as acetone and cyclohexanone; esters such as ethyl acetate and γ-butyrolactone; Carbonates such as carbonate and propylene carbonate; Amines such as triethylamine; Nitrogen-containing heterocyclic aromatic compounds such as pyridine; Nitriles such as acetonitrile and succinonitrile; N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl amides such as pyrrolidone; urea compounds such as tetramethylurea; nitro compounds such as nitromethane and nitrobenzene; sulfur compounds such as dimethylsulfoxide and sulfolane; You may use 2 or more types of them.

As the solvent, it is preferable to use a solvent mainly composed of an aprotic compound, particularly an aprotic compound having no halogen atom, because of its low corrosiveness and ease of handling. It is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, and particularly preferably 90% by mass to 100% by mass. Further, as the aprotic compound, amides such as N,N-dimethylformamide, N,N-dimethylacetamide, tetramethylurea, N-methylpyrrolidone, etc., or γ-butyrolactone, etc., can be used because they easily dissolve the liquid crystal polymer. Esters are preferably used, more preferably N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone.

As the solvent, a solvent mainly composed of a compound having a dipole moment of 3 to 5 is preferable because it easily dissolves the liquid crystal polymer. The proportion of the compound having a dipole moment of 3 to 5 in the total solvent is preferably 50% to 100% by mass, more preferably 70% to 100% by mass, and particularly preferably 90% to 100% by mass.
A compound having a dipole moment of 3 to 5 is preferably used as the aprotic compound.

As the solvent, it is preferable to use a solvent mainly composed of a compound having a boiling point of 220° C. or lower at 1 atm because it is easy to remove. is preferably 50% to 100% by mass, more preferably 70% to 100% by mass, and particularly preferably 90% to 100% by mass.
As the aprotic compound, it is preferable to use a compound having a boiling point of 220° C. or lower at 1 atm.

Further, when the film is produced by the casting method, the co-casting method, the coating method, the multi-layer coating method, the extrusion method, the co-extrusion method, or the like, a support may be used. In addition, when a metal layer (metal foil) or the like used in a laminate to be described later is used as a support, it may be used as it is without being peeled off.
Examples of the support include metal drums, metal bands, glass plates, resin films, and metal foils. Among them, metal drums, metal bands, and resin films are preferred.
Examples of resin films include polyimide (PI) films, and examples of commercially available products include U-Pyrex S and U-Pyrex R manufactured by Ube Industries, Ltd., Kapton manufactured by DuPont Toray Co., Ltd., and IF30, IF70 and LV300 manufactured by SKC Kolon PI, and the like.
Further, the support may have a surface-treated layer formed thereon so that it can be easily peeled off. Hard chrome plating, fluorine resin, or the like can be used for the surface treatment layer.
The average thickness of the resin film support is not particularly limited, but is preferably 25 μm or more and 75 μm or less, more preferably 50 μm or more and 75 μm.

The method for removing at least part of the solvent from the cast or coated film composition (cast film or coating film) is not particularly limited, and a known drying method can be used. .

<Stretching process>
The method for producing a film according to the present disclosure preferably includes a stretching step of stretching the film, and more preferably includes a stretching step of stretching the film between the forming step and the oxidation treatment step.
In the method for producing a film according to the present disclosure, stretching can be combined as appropriate from the viewpoint of controlling the molecular orientation of the resulting film and adjusting the coefficient of linear expansion and mechanical properties. The stretching method is not particularly limited, and known methods can be referred to, and it may be carried out in a solvent-containing state or in a dry film state. Stretching in a solvent-containing state may be performed by gripping and stretching the film, by utilizing the self-shrinking force of the web due to drying without stretching, or by a combination thereof. Stretching is particularly effective for the purpose of improving the elongation at break and the strength at break when the brittleness of the film is reduced by the addition of an inorganic filler or the like.

<Heating process>
A method for manufacturing a film according to the present disclosure may include a heating step of heating the film. The heating step may be performed before or after the oxidation treatment step.
It is presumed that the heating process promotes crystallization of the liquid crystal polymer in the film, and lowers the dielectric loss tangent of the film.
In the film manufacturing method according to the present disclosure, the dissolved oxygen content is preferably 500 ppm or less, more preferably 300 ppm or less, at the start of heating the film. When the dissolved oxygen content is within the above range, a film with a lower dielectric loss tangent can be obtained.
The term "at the start of heating" refers to the time at which application of heat to the film is started.

In the present disclosure, the dissolved oxygen content is measured using a dissolved oxygen meter, for example, using a portable oxygen analyzer "ORBISPHERE 3650" manufactured by Huck Ultra.

The heating temperature in the heating step is preferably 100°C to 400°C. Also, the heating time is preferably 0.1 minute to 10 hours. The heating temperature and heating time can be appropriately changed according to the type of polymer, and the temperature can be lowered or shortened by another means such as adding a catalyst.

The heating step may be performed under an inert gas atmosphere, or may be performed under an oxygen-containing atmosphere. From the viewpoint of production efficiency, the heating step is preferably performed in an atmosphere with an oxygen concentration of 500 ppm or more, and more preferably in an atmospheric (air) atmosphere.

<Winding process>
The method for producing a film according to the present disclosure preferably includes a winding step of winding the film into a roll, and a winding step of winding the film into a roll after the forming step and before the heating step. It is more preferable to include
The step of winding into a roll is preferably carried out under a nitrogen atmosphere. By carrying out the heating in a nitrogen atmosphere, the amount of dissolved oxygen in the film can be further reduced at the start of heating the film.

<Unwinding process>
The method for producing a film according to the present disclosure preferably includes an unwinding step of unwinding the roll-shaped film after the winding step.
Moreover, it is preferable that the peeling force when unwinding the film in the unwinding step is 1.0 kN/m or less.

<Peeling process>
The method for producing a film according to the present disclosure preferably includes a peeling step of peeling the film from the substrate after the forming step or after the heating step and before the oxidation treatment step. It is more preferable to include a peeling step of peeling the film from the substrate, and it is particularly preferable to include a peeling step of peeling the film from the substrate after the forming step and before the heating step. By peeling the film from the substrate, the film can be obtained and applied to other uses.

<Other processes>
The method for manufacturing a film according to the present disclosure may include other processes than those described above.
Other steps may include known steps.

(Laminated film)
The laminated film according to the present disclosure has a layer A and a layer B on at least one surface of the layer A, and the layer A is the film according to the present disclosure.

The elastic modulus of the layer B at 140° C. is preferably 0.1 MPa or less, more preferably 0.08 MPa or less, from the viewpoint of improving wiring followability and further suppressing wiring strain. The lower limit of the elastic modulus is not particularly limited, and is, for example, 0.0001 MPa.

Layer B preferably comprises a polymer.
Examples of polymers contained in layer B include liquid crystal polymers, fluorine-based polymers, polymers of compounds having a cycloaliphatic hydrocarbon group and a group having an ethylenically unsaturated bond, polyether ether ketones, polyolefins, polyamides, Thermoplastic polymers such as polyesters, polyphenylene sulfides, polyetherketones, polycarbonates, polyethersulfones, polyphenylene ethers and modified products thereof, and polyetherimides; elastomers such as copolymers of glycidyl methacrylate and polyethylene; phenolic resins, epoxy resins, Thermosetting polymers such as polyimide resins and cyanate resins can be used.

Above all, from the viewpoint of dielectric loss tangent, the layer B preferably contains a thermoplastic polymer. Also, the thermoplastic polymer is preferably a liquid crystal polymer.
In the present disclosure, a thermoplastic polymer means a polymer that softens when heated to its melting point.

Layer B preferably has a dielectric loss tangent of 0.006 or less, more preferably more than 0 and 0.003 or less.

The polymer content is preferably 10% by mass or more, more preferably 50% by mass or more, relative to the total mass of Layer B. The upper limit of the polymer content is not particularly limited, and may be 100% by mass.

Although the average thickness of the layer B is not particularly limited, it is preferably 0.1 μm to 10 μm, more preferably 1 μm to 5 μm.

The average thickness of each layer in the films of the present disclosure is measured using the following method.
The wiring board is cut with a microtome, and the cross section is observed with an optical microscope to evaluate the thickness of each layer. Three or more cross-sectional samples are cut out, the thickness is measured at three or more points in each cross section, and the average value thereof is taken as the average thickness.

Layer A and layer B may each independently contain other additives.
Preferred embodiments of other additives used in Layer A or Layer B are the same as the preferred embodiments of other additives described above.

(Laminate)
The laminate according to the present disclosure may be obtained by laminating the film according to the present disclosure, but a metal It is preferably a laminate having a substrate, and a resin layer containing a compound having a functional group and a metal substrate on one surface of the film according to the present disclosure or on either surface of the laminated film according to the present disclosure. and the functional group is an epoxy group, an oxetanyl group, an isocyanate group, an acid anhydride group, a carbodiimide group, an N-hydroxyester group, a glyoxal group, an imidoester group, a halogenated alkyl group, or a thiol group It is more preferable to be a laminate containing one or more of
In addition, the surface of the film on which the metal substrate is arranged is a surface that satisfies the range of surface free energy, a surface that satisfies the range of surface coverage, or a surface that satisfies the range of surface free energy and A surface that satisfies the range of surface coverage is preferred.

The surface roughness Rz of the film-side surface of the metal substrate is preferably 2.0 μm or less, more preferably 1.0 μm or less, and particularly preferably 0.5 μm or less. Within the above range, the surface resistance at the interface between the film and the metal substrate is lowered.

In the present disclosure, the “surface roughness Rz” is the total value of the maximum peak height and the maximum valley depth observed in the roughness curve at the reference length, expressed in nanometers. means.
In the present disclosure, the surface roughness Rz of the film-side surface of the metal substrate shall be measured by the following method.
Using a non-contact surface/layer cross-sectional shape measurement system VertScan (manufactured by Ryoka System Co., Ltd.), measure a square of 465.48 μm in length and 620.64 μm in width, and measure the surface roughness of the measurement object (liquid crystal polymer film). Create a curve and an average line of the roughness curve. A portion corresponding to the reference length is extracted from the roughness curve. The maximum value of the peak height (i.e., the height from the mean line to the peak) and the maximum value of the valley depth (i.e., the height from the mean line to the bottom of the valley) observed in the extracted roughness curve By obtaining the total value, the surface roughness Rz of the object to be measured is measured.

The metal substrate preferably has a metal layer or metal wiring on the surface, and more preferably has a copper layer or copper wiring on the surface.
The metal substrate, metal layer and metal wiring are not particularly limited as long as they are known metal substrates, metal layers and metal wiring. The metal layer and metal wiring are preferably, for example, silver layers, silver wiring, copper layers or copper wiring, and more preferably copper layers or copper wiring.
Moreover, it is preferable that the said metal substrate has metal wiring.
Furthermore, the metal in the metal layer and metal wiring is preferably silver or copper, more preferably copper.

The method for attaching the film according to the present disclosure and the metal substrate is not particularly limited, and a known lamination method can be used.

The peel strength between the film and the copper layer is preferably 0.5 kN/m or more, more preferably 0.7 kN/m or more, and is 0.7 kN/m to 2.0 kN/m. is more preferable, and 0.9 kN/m to 1.5 kN/m is particularly preferable.

In the present disclosure, the peel strength between a film and a metal layer (eg, copper layer) shall be measured by the following method.
A 1.0 cm wide peeling test piece was prepared from the laminate of the film and the metal layer, the film was fixed to a flat plate with double-sided adhesive tape, and the speed was 50 mm / min by the 90 ° method according to JIS C 5016 (1994). The strength (kN/m) is measured when the film is peeled from the metal layer at a speed of .

The metal layer is preferably a silver layer or a copper layer, more preferably a copper layer. The copper layer is preferably a rolled copper foil formed by a rolling method or an electrolytic copper foil formed by an electrolytic method, and more preferably a rolled copper foil from the viewpoint of bending resistance.

The average thickness of the metal substrate is not particularly limited, but is preferably 2 μm to 20 μm, more preferably 3 μm to 18 μm, even more preferably 5 μm to 12 μm. The metal substrate may be a carrier-attached metal foil that is releasably formed on a support (carrier). A known carrier can be used, and a resin film or the like can be preferably used as the carrier. Although the average thickness of the carrier is not particularly limited, it is preferably 10 μm to 100 μm, more preferably 18 μm to 50 μm.

The laminate according to the present disclosure preferably includes the film according to the present disclosure or the laminated film according to the present disclosure, a resin layer, and a metal substrate.
The resin layer contains a polymer. Preferred polymers include thermoplastic resins.
Thermoplastic resins include (meth)acrylic resin, polyvinyl cinnamate, polycarbonate, polyimide, polyamideimide, polyesterimide, polyetherimide, polyetherketone, polyetheretherketone, polyethersulfone, polysulfone, and polyparaxylene. , polyester, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, polyurethane, polyvinyl alcohol, cellulose acylate, fluorinated resin, liquid crystal polymer, syndiotactic polystyrene, silicone resin, epoxy silicone resin, phenolic resin, alkyd Resins, epoxy resins, maleic acid resins, melamine resins, urea resins, aromatic sulfonamides, benzoguanamine resins, silicone elastomers, aliphatic polyolefins (eg, polyethylene, polypropylene), cyclic olefin copolymers, and the like. Among them, at least one resin selected from the group consisting of polyimide, liquid crystal polymer, syndiotactic polystyrene, and cyclic olefin copolymer is preferable, and polyimide is more preferable, from the viewpoint of more exhibiting the effects of the present disclosure.

The resin content is preferably 60% by mass to 99.9% by mass, more preferably 70% by mass to 99.0% by mass, and 80% by mass to 97.0% by mass with respect to the total mass of the resin layer. More preferred.

A material other than the polymer that constitutes the resin layer is not particularly limited, and may be either an organic substance or an inorganic substance, or a combination of an organic substance and an inorganic substance.
From the viewpoint of adhesion to the metal substrate, the resin layer is preferably an adhesive layer, more preferably an adhesive layer containing an adhesive.

In the present disclosure, the type of adhesive is not particularly limited, and known adhesives can be used.
Thermosetting resins are preferably used as polymers for the adhesive.
Examples of thermosetting resins include epoxy resins, phenol resins, unsaturated imide resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins. resins, triazine resins, melamine resins, and the like. Moreover, the thermosetting resin is not particularly limited to these, and known thermosetting resins can be used. These thermosetting resins can be used alone or in combination of multiple types.
As the adhesive, a commercially available thermosetting resin-containing adhesive can also be used.

From the viewpoint of adhesion to the metal substrate, the resin layer preferably contains a compound having a reactive group.
The reactive group is preferably a group capable of reacting with a group that may exist on the surface of the polymer film (in particular, a group having an oxygen atom such as a carboxy group and a hydroxy group).
Reactive groups include epoxy group, oxetanyl group, isocyanate group, acid anhydride group, carbodiimide group, N-hydroxyester group, glyoxal group, imidoester group, alkyl halide, and and, preferably at least one group selected from the group consisting of a thiol group, more preferably at least one group selected from the group consisting of an epoxy group, an acid anhydride group, and a carbodiimide group, epoxy groups are more preferred.

Specific examples of reactive compounds having an epoxy group include aromatic glycidylamine compounds (e.g., N,N-diglycidyl-4-glycidyloxyaniline, 4,4′-methylenebis(N,N-diglycidylaniline), N , N-diglycidyl-o-toluidine, N,N,N',N'-tetraglycidyl-m-xylylenediamine, 4-t-butylphenylglycidyl ether), aliphatic glycidylamine compounds (e.g., 1,3-bis (diglycidylaminomethyl)cyclohexane, etc.) and aliphatic glycidyl ether compounds (eg, sorbitol polyglycidyl ether). Among them, aromatic glycidylamine compounds are preferable from the viewpoint of exhibiting the effects of the present disclosure more.

Specific examples of reactive compounds having an acid anhydride group include tetracarboxylic dianhydrides (eg, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, 3,3′,4,4 '-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, oxydiphthalic dianhydride, diphenylsulfone-3,4,3' ,4'-tetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)sulfide dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3 ,3-hexafluoropropane dianhydride, 2,3,3′,4′-benzophenonetetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3 ,4-dicarboxyphenyl)propane dianhydride, p-phenylene bis (trimellitic monoester anhydride), p-biphenylene bis (trimellitic monoester anhydride), m-terphenyl-3,4 ,3′,4′-tetracarboxylic dianhydride, p-terphenyl-3,4,3′,4′-tetracarboxylic dianhydride, 1,3-bis(3,4-dicarboxyphenoxy) Benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-bis[( 3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4 '-(2,2-hexafluoroisopropylidene)diphthalic dianhydride).

Specific examples of reactive compounds having a carbodiimide group include monocarbodiimide compounds (e.g., dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, t-butylisopropylcarbodiimide, diphenylcarbodiimide, di-t-butylcarbodiimide, di-β-naphthylcarbodiimide, N,N'-di-2,6-diisopropylphenylcarbodiimide), polycarbodiimide compounds (e.g., US Pat. No. 2,941,956, JP-B-47-33279, J.Org.Chem ., vol.28, p.2069-2075 (1963) and Chemical Review, 1981, vol.81, No. 4, p.619-621, etc.).
Commercially available reactive compounds having a carbodiimide group include Carbodilite HMV-8CA, LA-1, V-03 (manufactured by Nisshinbo Chemical Co., Ltd.), Stabaxol P, P100, P400 (manufactured by Rhein Chemie), Stabilizer 9000 (Rashih Chemie). company) and the like.

The number of reactive groups possessed by the reactive compound is 1 or more, but preferably 3 or more from the viewpoint of better adhesion of the metal layer.
The number of reactive groups possessed by the reactive compound is preferably 6 or less, more preferably 5 or less, and even more preferably 4 or less, in order to obtain a laminate having a lower dielectric loss tangent in portions other than the metal layer. .

The resin layer may contain only one type of reactive compound, or may contain two or more types.
The content of the reactive compound is preferably 0.1% by mass to 40% by mass, more preferably 1% by mass to 30% by mass, and even more preferably 3% by mass to 20% by mass, relative to the total mass of the resin layer. . If it is at least the lower limit value, the adhesion of the metal layer is more excellent, and if it is at most the upper limit value, a laminate having a lower dielectric loss tangent in portions other than the metal layer can be obtained.

The resin layer may contain additives other than the adhesive.
As other additives, known additives can be used. Specific examples include leveling agents, antifoaming agents, antioxidants, ultraviolet absorbers, flame retardants, coloring agents, fillers, and the like.

The thickness of the resin layer is 1 μm or less, and is preferably 0.8 μm or less, more preferably 0.7 μm or less, and 0.6 μm or less in order to form a laminate having a lower dielectric loss tangent in portions other than the metal layer. More preferred.
The thickness of the resin layer is preferably 0.05 μm or more, more preferably 0.1 μm or more, and even more preferably 0.2 μm or more, from the viewpoint of better adhesion of the metal layer.
The thickness of the resin layer is measured based on a cross-sectional image of the film with the resin layer by a scanning electron microscope (SEM), and is the arithmetic mean value of the measured values of the thickness of the resin layer at 100 arbitrary different points.

-elastic modulus-
The elastic modulus at 25° C. after curing of the resin layer is 0.8 GPa or more, and is preferably 1.0 GPa or more, more preferably 1.1 GPa or more, more preferably 1.2 GPa or more, in terms of better adhesion of the metal layer. is more preferred.
The upper limit of the elastic modulus of the resin layer after curing is not particularly limited, and is, for example, 5 GPa or less.

－Dielectric loss tangent－
The dielectric loss tangent after curing of the resin layer is preferably 0.01 or less, more preferably 0.008 or less, more preferably 0.008 or less, and further 0.005 or less, because a laminate with a lower dielectric loss tangent in portions other than the metal layer can be formed. preferable. The lower limit is not particularly limited, and may be 0.0001 or more.

It is also preferable to process the metal layer in the laminate according to the present disclosure into a desired circuit pattern by etching, for example, to form a flexible printed circuit board. The etching method is not particularly limited, and known etching methods can be used.

The method for producing a laminate according to the present disclosure preferably includes a resin layer forming step of providing a resin layer on at least one surface of the film, and a lamination step of laminating the resin layer and a metal substrate.
A method for forming the resin layer is not particularly limited, and a known coating method and a known adhesive application method can be used.
Moreover, in the lamination step, it is preferable to bond the metal wiring.
A lamination method in the lamination step is not particularly limited, and a known lamination method can be used.
The bonding pressure in the lamination step is not particularly limited, but is preferably 0.1 MPa or more, preferably 0.2 MPa to 10 MPa.
The bonding temperature in the lamination step can be appropriately selected according to the film to be used, etc., but is preferably 150° C. or higher, and more preferably 170° C. or higher and 250° C. or lower.
Further, the method for manufacturing a laminate according to the present disclosure preferably includes a step of cooling the laminate in order to cure and adhere the resin layer, for example, when a hot-melt adhesive is used as the resin layer.

EXAMPLES The present disclosure will be described more specifically with reference to examples below. Materials, usage amounts, proportions, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the gist of the present disclosure. Accordingly, the scope of the present disclosure is not limited to the specific examples shown below.
"Parts" and "%" are based on mass unless otherwise specified.

LCP film A (LCP-A): "Vecstar CTQ-25" manufactured by Kuraray Co., Ltd., thickness 25 μm, polymer film containing liquid crystal polymer

LCP film B (LCP-B): A film in which polyolefin forms a dispersed phase, produced by the method described below.

<Raw materials used>
Liquid crystal polymer B: A polymer synthesized according to Example 1 of JP-A-2019-116586. It corresponds to a thermotropic liquid crystal polymer with a melting point of 320°C. LCP-B is a structural repeating unit derived from 6-hydroxy-2-naphthoic acid, a structural repeating unit derived from 4,4'-dihydroxybiphenyl, a structural repeating unit derived from terephthalic acid, and 2,6-naphthalene It is composed of structural repeating units derived from dicarboxylic acids.
Polyolefin: Nippon Polyethylene Co., Ltd. Novatec LD (low density polyethylene)
Compatible component: ethylene / glycidyl methacrylate copolymer Thermal stabilizer: ADEKA Corporation "AO-80" (semi-hindered phenolic stabilizer)

<Supply process>
The liquid crystal polymer B, polyolefin, compatible component, and heat stabilizer were mixed according to the formulation shown below, and kneaded into pellets using an extruder.
・Liquid crystal polymer B: 84.5%
・ Polyolefin: 12.4%
・Compatible component: 2.5%
・Heat stabilizer: 0.6%
The pellets obtained by kneading and pelletizing were dried at 80° C. for 12 hours using a dehumidifying hot air dryer with a dew point temperature of −45° C. to reduce the moisture content to 200 ppm or less.
The pellets dried in this manner are also referred to as raw material A.

<Film forming process>
Raw material A is supplied into the cylinder from the same supply port of a twin-screw extruder with a screw diameter of 50 mm, heated and kneaded, and discharged from a die with a width of 750 mm onto a rotating cast roll in the form of a film of raw material A in a molten state. A film having a thickness of 150 μm was obtained by cooling and solidifying with a heat source and stretching as desired.
The temperature for heating and kneading, the speed at which raw material A was discharged, the clearance of the die lip, and the peripheral speed of the cast roll were each adjusted within the following ranges.
・Temperature for heating and kneading: 270°C to 350°C
・Clearance: 0.01mm to 5mm
・Discharge speed: 0.1 mm/sec to 1,000 mm/sec
・Peripheral speed of cast roll: 0.1 m/min to 100 m/min

<Lateral stretching process>
The film produced in the film forming process was stretched in the TD direction (the width direction of the film) using a tenter. The draw ratio at this time was 3.2 times.

<Post-heat treatment>
Both ends in the width direction of the film subjected to the lateral stretching step were held with jigs and fixed so that the film would not shrink in the width direction. The film in this fixed state was post-heated using an infrared heater or a hot air dryer.
In the post-heating treatment using an infrared heater, both sides of the film were heated at a film surface temperature of 300° C. for 30 seconds using a pair of infrared heaters.
In the post-heating treatment using a hot air dryer, the film fixed with a jig was placed in a hot air dryer and heated for 180 seconds at a film surface temperature of 300 ° C., then the film was removed from the hot air dryer and LCP film B was obtained. (55 μm) was obtained.
In the heat treatment process, a film surface temperature measurement film is placed near the film to be heat treated, and a thermocouple attached to the surface of the film surface temperature measurement film with a polyimide tape is used to measure the film surface temperature. was measured.

(Example 1)
After adding sodium persulfate water (sodium persulfate: 2.4 g/water: 25 mL) to NaOH water (NaOH: 10 g / water: 100 mL), the liquid heated to 50 ° C. was coated with LCP film A (3 cm × 8 cm ) was soaked for 20 minutes. After 20 minutes, the LCP film was taken out, washed with 100 mL of water, and dried at room temperature (25° C., hereinafter the same) to obtain surface-modified LCP film 1 (LCP-F1).

(Example 2)
NaOH water (NaOH: 10 g / water: 100 mL), sodium persulfate water (sodium persulfate: 2.4 g / water: 25 mL) and iron sulfate heptahydrate (0.28 g) were added, and then heated to 50 ° C. The LCP film A (3 cm×8 cm) was immersed in the liquid heated to 20 minutes. After 20 minutes, the LCP film was taken out, washed with 100 mL of water, and dried at room temperature to obtain surface-modified LCP film 2 (LCP-F2).

(Example 3)
After adding sodium hypochlorite water (sodium hypochlorite pentahydrate: 2.4 g / water: 25 mL) to water (100 mL), the mixture was heated to 50 ° C. and added to the LCP film. A (3 cm x 8 cm) was soaked for 20 minutes. After 20 minutes, the LCP film was taken out, washed with 100 mL of water, and dried at room temperature to obtain surface-modified LCP film 3 (LCP-F3).

(Example 4)
After adding cerium ammonium nitrate water (cerium ammonium nitrate: 2.4 g / water: 25 mL) to NaOH water (NaOH: 10 g / water: 100 mL), the NaOH water was heated to 50 ° C. LCP film A was added to the liquid. (3 cm x 8 cm) was soaked for 20 minutes. After 20 minutes, the LCP film was taken out, washed with 100 mL of water, and dried at room temperature to obtain surface-modified LCP film 4 (LCP-F4).

(Example 5)
Example 1 except that the sodium persulfate water containing "sodium persulfate: 2.4 g/water: 25 mL" was changed to sodium persulfate water containing "sodium persulfate: 12 g/water: 25 mL". A surface-modified LCP film 5 (LCP-F5) was obtained in the same manner as in Example 1.

(Example 6)
The surface was prepared in the same manner as in Example 1 except that the NaOH water containing "NaOH: 10 g / water: 100 mL" in Example 1 was changed to NaOH water containing "NaOH: 0.5 g / water: 100 mL". A modified LCP film 6 (LCP-F6) was obtained.

(Example 7)
Except that the sodium persulfate water containing "sodium persulfate: 2.4 g/water: 25 mL" in Example 1 was changed to potassium iodate water containing "potassium iodate: 2.4 g/water: 25 mL". obtained a surface-modified LCP film 7 (LCP-F7) in the same manner as in Example 1.

(Example 8)
The surface was prepared in the same manner as in Example 1 except that the NaOH water containing "NaOH: 10 g / water: 100 mL" in Example 1 was changed to NaOH water containing "NaOH: 0.005 g / water: 100 mL". A modified LCP film 8 (LCP-F8) was obtained.

(Example 9)
Except that the sodium persulfate water containing "sodium persulfate: 2.4 g/water: 25 mL" in Example 1 was changed to potassium persulfate water containing "potassium persulfate: 2.4 g/water: 25 mL". obtained a surface-modified LCP film 9 (LCP-F9) in the same manner as in Example 1.

(Example 10)
The procedure was carried out except that the sodium persulfate water containing "sodium persulfate: 2.4 g/water: 25 mL" in Example 1 was changed to ammonium persulfate water containing "ammonium persulfate: 2.4 g/water: 25 mL". A surface-modified LCP film 10 (LCP-F10) was obtained in the same manner as in Example 1.

(Example 11)
A surface-modified LCP film 11 (LCP-F11) was obtained in the same manner as in Example 1 except that LCP film A in Example 1 was changed to LCP film B.

(Example 12)
After adding sodium persulfate water (sodium persulfate: 2.4 g/water: 25 mL) to NaOH water (NaOH: 10 g / water: 100 mL), the liquid heated to 50 ° C. was coated with LCP film A (3 cm × 8 cm ) was allowed to float for 20 minutes so that only one side was in contact with the treatment liquid. After 20 minutes, the LCP film was taken out, washed with 100 mL of water, and dried at room temperature to obtain a surface-modified LCP film 12 (LCP-F12) in which only one side was surface-modified.

(Comparative Example 3)
An LCP film A (3 cm×8 cm) was immersed in a solution of NaOH water (NaOH: 10 g/water: 100 mL) heated to 50° C. for 20 minutes. After 20 minutes, the LCP film was taken out, washed with 100 mL of water, and dried at room temperature to obtain surface-modified LCP film 13 (LCP-F13).

<Method for measuring water contact angle on film surface>
The water contact angles of the LCP films (LCP-F1 to 13, and LCP-A and B) were measured at 25° C. and 50% RH (LCP-12 measured the treated surface). A contact angle meter (DM700) manufactured by Kyowa Interface Science Co., Ltd. was used for the measurement. The contact angle was calculated by averaging 10 points by reading the contact angle 5 seconds after the droplet was prepared. The value measured by the above method is defined as the water contact angle on the film surface of the LCP films (LCP-F1 to 13, and LCP-A and B).

<Method for measuring surface free energy>
The contact angle of the film surface to diiodomethane was measured by the same method as the method for measuring the water contact angle of the film surface, and the surface free energy was calculated based on the Owens equation.

<Method for measuring the water contact angle inside the film>
The LCP films (LCP-F1 to 13, and LCP-A and B) were melted by heating to the melting point or higher, and then molded into films again. It is thought that the original surface and the inside are completely confused because they have been heated above the melting point once. The water contact angle of the LCP film obtained in this way was measured by the same method as above, and the water contact angle inside the LCP film (LCP-F1 to 13, and LCP-A and B). Define.

The water contact angle on the particle surface of the LCP films (LCP-A and B) before the surface modification treatment was consistent with the water contact angle inside the film.
In addition, the water contact angles inside the LCP films (LCP-F1 to 13) coincided with the water contact angles inside and on the film surface of the LCP films (LCP-A and B) before the surface modification treatment.

<Peel strength>
- Laminate production method -
Polyimide resin solution ("PIAD-200" manufactured by Arakawa Chemical Industries, Ltd., solid content 30% by mass, solvent: cyclohexane, methylcyclohexane and ethylene glycol dimethyl ether) 17.7 g, N,N-diglycidyl-4-glycidyloxyaniline ( (manufactured by Sigma-Aldrich Co.) and 1.97 g of toluene were mixed and stirred to obtain an adhesive varnish 1 (composition for forming an adhesive layer) having a solid content concentration of 28% by mass.
The resulting adhesive varnish 1 was applied to one side of the LCP film (the treated side for LCP-12) using an applicator. By drying the coating film at 85° C. for 1 hour, an adhesive layer (resin layer) having a thickness of 0.8 μm was provided to prepare an LCP film with an adhesive layer.

An LCP film with an adhesive layer and a non-roughened copper foil (“CF-T9DA-SV-18” manufactured by Fukuda Metal Foil & Powder Co., Ltd., thickness 18 μm) were combined with the adhesive layer of the film with an adhesive layer and the non-roughened copper foil. Laminated so that the non-roughened surface (maximum height Rz 0.85 μm) of the heat treated copper foil is in contact with each other, then using a heat press (manufactured by Toyo Seiki Seisakusho Co., Ltd.) at 200 ° C. and 4 MPa A laminate was produced by laminating the LCP film, the resin layer (cured film of the adhesive layer), and the metal layer (copper foil) in this order.

- Initial peel strength test measurement -
Each laminate was cut into strips of 1 cm×5 cm to prepare samples. The peel strength (unit: N/cm) of the obtained sample was measured according to the method for measuring peel strength under normal conditions described in JIS C 6481. Peeling of the metal layer from the sample in the peel strength test was performed at an angle of 90° to the sample at a peel speed of 50 mm/min. Evaluation criteria are shown below.
A: Peel strength of 4 N/cm or more B: Peel strength of 3 N/cm or more and less than 4 N/cm C: Peel strength of 2 N/cm or more and less than 3 N/cm D: Peel strength of less than 2 N/cm

-Measurement of peel strength after wet heat aging-
After placing each laminate in an atmosphere of 85° C. and 85% RH for 500 hours, the same peel strength test as above was conducted. Evaluation criteria are shown below.
A: Peel strength of 4 N/cm or more B: Peel strength of 3 N/cm or more and less than 4 N/cm C: Peel strength of 2 N/cm or more and less than 3 N/cm D: Peel strength of less than 2 N/cm

The internal contact angle of each of the films of Examples 1 to 10 and 12 was 84°, and the internal contact angle of the film of Example 11 was 85°.
In addition, each of the films of Examples 1 to 12 had an elastic modulus of 300 MPa or more at 240° C. on one surface.

As shown in Table 1, the films of Examples 1-12 were superior to the films of Comparative Examples 1-3 in peel strength to the metal substrate via the adhesive layer.

(Examples 101-112)
Polyimide resin solution (above-mentioned "PIAD-200") 17.7 g, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.27 g, and toluene 1 By mixing 97 g and stirring, an adhesive varnish 2 (composition for forming an adhesive layer) having a solid content concentration of 28% by mass was obtained.
In Examples 1 to 12, even when the adhesive varnish 2 was used instead of the adhesive varnish 1, respectively, the same peel strength and peel strength after wet heat aging as in Examples 1 to 12 were obtained.

Claims (23)

containing a liquid crystal polymer,
A film having a difference of 7° or more between the inside of the film and one surface of the film in the contact angle with water measured by the water-in-air method at 25°C and 50% RH. The film according to claim 1, wherein the surface free energy on one surface of said film is from 47 N/m to 60 N/m. 3. The film according to claim 1, wherein the contact angle of water on one surface of the film at 25[deg.] C. and 50% RH is 50[deg.] or more and less than 75[deg.]. 4. Any one of claims 1 to 3, wherein the difference between the contact angle with water measured by the water droplet method at 25° C. and 50% RH between the inside of the film and one surface of the film is 7° or more and 32° or less. or the film according to item 1. The film according to any one of claims 1 to 4, wherein one surface of the film has a surface roughness Ra of 0.05 µm or less. The liquid crystal polymer comprises a liquid crystal polymer having at least one structural unit selected from the group consisting of structural units derived from parahydroxybenzoic acid and structural units derived from 6-hydroxy-2-naphthoic acid. The film according to any one of claims 1 to 5. The liquid crystal polymer comprises a structural unit derived from 6-hydroxy-2-naphthoic acid, a structural unit derived from an aromatic diol compound, a structural unit derived from terephthalic acid, and a structure derived from 2,6-naphthalenedicarboxylic acid. 6. The film according to any one of claims 1 to 5, comprising a liquid crystal polymer having at least one structural unit selected from the group consisting of units. The film according to any one of claims 1 to 7, further comprising a polyolefin. 9. The film according to claim 8, wherein the content of said polyolefin is 0.1% by mass to 40% by mass with respect to the total mass of said film. 10. A film according to claim 8 or 9, wherein said polyolefin forms a dispersed phase in said film. 11. The film according to claim 10, wherein the dispersed phase has an average dispersed diameter of 0.01 μm to 10 μm. The film according to any one of claims 1 to 11, wherein one surface of the film has an elastic modulus at 240°C of 300 MPa or more. Having a layer A and a layer B on at least one surface of the layer A,
A laminated film, wherein the layer A is the film according to any one of claims 1 to 12. The laminated film according to claim 13, wherein the layer B has an elastic modulus at 140°C of 0.1 MPa or less. A laminate having a metal substrate on one surface of the film according to any one of claims 1 to 12 or on the layer B side surface of the laminated film according to claim 13 or 14. A resin containing a compound having a functional group on one surface of the film according to any one of claims 1 to 12 or on either surface of the laminated film according to claim 13 or 14. a layer and a metal substrate;
The functional group is one or more of an epoxy group, an oxetanyl group, an isocyanate group, an acid anhydride group, a carbodiimide group, an N-hydroxyester group, a glyoxal group, an imidoester group, a halogenated alkyl group, and a thiol group. including a laminate. 17. The laminate according to claim 15, wherein the maximum height Rz of the film-side surface of the metal substrate is 2.0 [mu]m or less. including an oxidation treatment step of oxidizing the surface of the film containing the liquid crystal polymer,
The film produced has a difference of 7° or more between the inside of the film and one surface of the film in contact angle with water measured by the water droplet method at 25°C and 50% RH. 19. The production of the film according to claim 18, comprising an oxidation treatment step in which the contact angle with water on one surface of the produced film is 50° or more and less than 75° by the water droplet method at 25°C and 50% RH. Method. 20. The method for producing a film according to claim 18 or 19, wherein the oxidation treatment step is a step of contacting the surface of the film with an oxidizing agent in an aqueous solution. 21. The method for producing a film according to claim 20, wherein the oxidizing agent has a standard oxidation-reduction potential of 1.5 V or higher. The oxidizing agent is sodium persulfate, potassium persulfate, ammonium persulfate, hydrogen peroxide, potassium permanganate, sodium hypochlorite, ammonium cerium nitrate, potassium chromate, potassium dichromate, and potassium peroxymonosulfate. 22. The method for producing a film according to claim 20 or 21, comprising at least one compound selected from the group consisting of double salts consisting of potassium hydrogensulfate and potassium sulfate. The method for producing a film according to any one of claims 20 to 22, wherein the aqueous solution has a pH of 12 or higher.