Polymer films and laminates

Abstract

Provided are a polymer film that exhibits an excellent adhesiveness to substrate, and a laminate that uses the polymer film. The polymer film comprises a polymer having a dielectric loss tangent of less than or equal to 0.005 and a functional group-bearing compound, and the concentration of the functional group-bearing compound is higher at at least one surface than in the interior.

Description

[Technical Field]

[0001] The present disclosure relates to polymer films and laminates. [Background technology]

[0002] In recent years, the frequencies used in communication devices have tended to become very high. To suppress transmission loss in high-frequency bands, it has become necessary to lower the relative permittivity and dielectric loss tangent of insulating materials used in circuit boards. Conventionally, polyimide has been widely used as an insulating material for circuit boards, but liquid crystal polymers have been attracting attention because of their high heat resistance, low water absorption, and low loss in the high frequency band.

[0003] As an example of a conventional liquid crystal polymer film, Patent Document 1 describes a liquid crystal polyester film containing at least a liquid crystal polyester, in which when a first orientation degree is an orientation degree in a first direction parallel to the main surface of the liquid crystal polyester film and a second orientation degree is an orientation degree in a second direction parallel to the main surface and perpendicular to the first direction, the ratio of the first orientation degree to the second orientation degree, i.e., first orientation degree / second orientation degree, is 0.95 or more and 1.04 or less, and the third orientation degree of the liquid crystal polyester measured by wide-angle X-ray scattering in a direction parallel to the main surface is 60.0% or more.

[0004] Furthermore, as a conventional functional film, the one described in Patent Document 2 is known. Patent Document 2 describes a copolymer containing a repeating unit represented by the following general formula (I) and a repeating unit represented by the following general formula (II), and / or a functional film containing a crosslinked reaction product derived from the above copolymer.

[0005] [ka]

[0006] In general formula (I), R1 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and R 2 is an alkyl group having 1 to 20 carbon atoms and having at least one fluorine atom as a substituent, or -Si(R a3 )(R a4 R represents a group containing -O-, -(C=O)O-, -O(C=O)-, a divalent aliphatic chain group, and a divalent aliphatic cyclic group. a3 and R a4 each independently represents an alkyl group having 1 to 12 carbon atoms which may have a substituent.

[0007] [ka]

[0008] In general formula (II), R 10 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and R 11 and R 12 each independently represents a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group; R 11 and R 12 may be linked to X. 1 represents a divalent linking group. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2020-26474 [Patent Document 2] Japanese Patent Application Publication No. 2018-5215 Summary of the Invention [Problem to be solved by the invention]

[0010] The problem to be solved by the embodiments of the present invention is to provide a polymer film that has excellent adhesion to a substrate. Another problem to be solved by the embodiments of the present invention is to provide a laminate using the above polymer film. [Means for solving the problem]

[0011] The means for solving the above problems include the following aspects. <1> A polymer film comprising a polymer having a dielectric loss tangent of 0.005 or less and a compound having a functional group, wherein the concentration of the compound having a functional group is higher on at least one surface than in the interior. <2> A polymer film comprising a polymer having a dielectric loss tangent of 0.005 or less and a compound having a functional group, wherein the surface coverage of the compound having the functional group on at least one surface of the polymer film is 50 area % or more. <3> The functional group is at least one group selected from the group consisting of a group capable of forming a covalent bond, a group capable of forming an ionic bond, a group capable of forming a hydrogen bond, and a group capable of forming a dipole-dipole interaction. <1> or <2> The polymer film according to claim 1. <4> The functional group is a group capable of covalent bonding. <3> The polymer film according to claim 1. <5> The covalently bondable group is at least one group selected from the group consisting 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 imide ester group, a halogenated alkyl group, and a thiol group. <4> The polymer film according to claim 1. <6> The compound having the functional group contains a silicon atom or a fluorine atom. <1> ~ <5> 10. The polymer film according to any one of the preceding items. <7> The polymer film further includes a third component that fixes the compound having the functional group to the polymer having a dielectric loss tangent of 0.005 or less. <1> ~ <6> 10. The polymer film according to any one of the preceding items. <8> The third component contains a cured product of a polyfunctional reactive compound. <7> The polymer film according to claim 1. <9> the third component contains a polymer having a functional group that interacts with the compound having the functional group and that is compatible with the polymer having a dielectric loss tangent of 0.005 or less; <7> or <8> The polymer film according to claim 1. <10> The difference between the SP value by the Hoy method of the polymer having a dielectric loss tangent of 0.005 or less and the SP value by the Hoy method of the compound having the functional group is 5 MPa 0.5 Below is the <1> ~ <9> 10. The polymer film according to any one of the preceding items. <11> The polymer film has a layer A and a layer B on at least one surface of the layer A, and the layer B contains the compound having the functional group. <1> ~ <10> 10. The polymer film according to any one of the preceding items. <12> The layer B includes a third component that fixes the compound having the functional group to the polymer having a dielectric loss tangent of 0.005 or less. <11> The polymer film according to claim 1. <13> The content of the third component in the layer B is greater than the content of the third component in the layer A. <12> The polymer film according to claim 1. <14> The laminate further includes a layer C, and includes the layer B, the layer A, and the layer C in this order. <11> ~ <13> 10. The polymer film according to any one of the preceding items. <15> The linear expansion coefficient of the polymer film is -20 ppm / K to 50 ppm / K. <1> ~ <14> 10. The polymer film according to any one of the preceding items. <16> The dielectric loss tangent of the polymer film is 0.01 or less. <1> ~ <15> 10. The polymer film according to any one of the preceding items. <17> The polymer film contains a filler. <1> ~ <16> 10. The polymer film according to any one of the preceding items. <18> The number density of the filler is greater inside the polymer film than on the surface. <17> The polymer film according to claim 1. <19> The polymer having a dielectric loss tangent of 0.005 or less includes a liquid crystal polymer. <1> ~ <18> 10. The polymer film according to any one of the preceding items. <20> The polymer having a dielectric loss tangent of 0.005 or less includes a liquid crystal polymer having a constitutional unit represented by any one of formulas (1) to (3). <19> The polymer film according to claim 1. 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, a naphthylene group, or a biphenylylene group; Ar 2 and Ar 3 each independently represents a phenylene group, a naphthylene group, a biphenylylene group, or a group represented by the following formula (4), X and Y each independently represent an oxygen atom or an imino group, Ar 1 ~Ar 3 Each hydrogen atom in may be independently substituted with a halogen atom, an alkyl group, or an aryl group. Formula (4) -Ar 4 -Z-Ar 5 - In formula (4), Ar 4 and Ar 5 each independently represents 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. <21> A polymer film comprising a liquid crystal polymer and a compound having a functional group, wherein the concentration of the compound having a functional group is higher on at least one surface than in the interior. <22> A polymer film comprising a liquid crystal polymer and a compound having a functional group, wherein the surface coverage of at least one surface of the polymer film with the compound having a functional group is 50 area % or more. <23> <1> ~ <22> and a metal layer disposed on a surface of the polymer film where the concentration of the compound having the functional group is higher than in the interior of the polymer film. <24> A metal layer is disposed on each side of the polymer film. <23> The laminate according to claim 1. <25> The metal layer is a copper layer, and the peel strength between the polymer film and the copper layer is 0.5 kN / m or more. <23> or <24> The laminate according to claim 1. <26> The polymer film has a layer A and a layer B on at least one surface of the layer A, the layer B contains the compound having the functional group, and the metal layer is disposed on the layer B. <23> ~ <25> 10. The laminate according to claim 9, wherein the first and second laminates are oriented in a direction perpendicular to the plane of the [Effects of the Invention]

[0012] According to an embodiment of the present invention, a polymer film having excellent adhesion to a substrate can be provided. According to another embodiment of the present invention, a laminate using the above polymer film can be provided. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present disclosure will be described in detail below. The following description of the components may be based on representative embodiments of the present disclosure, but the present disclosure is not limited to such embodiments. In this specification, the use of "to" to indicate a range of values ​​means that the values ​​before and after it are included as the lower and upper limits. In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples. Furthermore, in the description of groups (atomic groups) in this specification, a description that does not specify whether it is substituted or unsubstituted includes both unsubstituted and substituted groups. For example, the term "alkyl group" includes not only alkyl groups that do not have a substituent (unsubstituted alkyl groups) but also alkyl groups that have a substituent (substituted alkyl groups). In this specification, "(meth)acrylic" is a term used as a concept that includes both acrylic and methacrylic, and "(meth)acryloyl" is a term used as a concept that includes both acryloyl and methacryloyl. Furthermore, the term "process" in this specification does not only refer to an independent process, but also includes a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved. In addition, in the present disclosure, "mass %" and "wt %" are synonymous, and "parts by mass" and "parts by weight" are synonymous. Furthermore, in the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. Furthermore, unless otherwise specified, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) in the present disclosure are molecular weights calculated using a gel permeation chromatography (GPC) analyzer with a TSKgel SuperHM-H (trade name of Tosoh Corporation) column, a solvent of PFP (pentafluorophenol) / chloroform = 1 / 2 (mass ratio), detection with a differential refractometer, and conversion using polystyrene as a standard substance.

[0014] (polymer film) A first embodiment of the polymer film according to the present disclosure comprises a polymer having a dielectric loss tangent of 0.005 or less and a compound having a functional group, wherein the concentration of the compound having the functional group is higher on at least one surface than in the interior. A second embodiment of the polymer film according to the present disclosure comprises a polymer having a dielectric loss tangent of 0.005 or less and a compound having a functional group, and the surface coverage of the compound having the functional group on at least one surface of the polymer film is 50 area % or more. A third embodiment of the polymer film according to the present disclosure includes a liquid crystal polymer and a compound having a functional group, and the concentration of the compound having a functional group is higher on at least one surface than in the interior. A fourth embodiment of the polymer film according to the present disclosure comprises a liquid crystal polymer and a compound having a functional group, and the surface coverage of the compound having the functional group on at least one surface of the polymer film is 50 area % or more.

[0015] In this specification, when the term "polymer film according to the present disclosure" or "polymer film" is used without any particular specification, it refers to all of the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment.

[0016] Many conventional polymer films have a large dielectric loss tangent. Furthermore, among conventional polymer films, those with a small dielectric loss tangent do not have sufficient adhesion to substrates (e.g., plastic films, metal foils, or metal wiring). As a result of extensive research, the present inventors have found that the above-described structure makes it possible to provide a polymer film having excellent adhesion to a substrate. The detailed mechanism by which the above effects are obtained is unknown, but is speculated as follows. The film contains a polymer or liquid crystal polymer having a dielectric dissipation factor of 0.005 or less and a compound having a functional group, and the concentration of the compound having the functional group on at least one surface is higher than in the interior, or the surface coverage of the compound having the functional group on at least one surface of the polymer film is 50 area % or more.It is therefore presumed that even when a polymer or liquid crystal polymer having a dielectric dissipation factor of 0.005 or less is used, the compound having the functional group is present on the surface of the polymer film and interacts with the substrate or groups present on the substrate surface, resulting in excellent adhesion to the substrate. Furthermore, although compounds having functional groups have a relatively high dielectric loss tangent, it is presumed that the total amount added can be reduced by increasing the concentration on the surface, resulting in a polymer film with a good dielectric loss tangent.

[0017] In the first and third embodiments of the polymer film according to the present disclosure, the concentration of the compound having the functional group on at least one surface is higher than that inside, and from the viewpoints of the dielectric loss tangent of the polymer film and adhesion to the metal layer, the concentration of the compound having the functional group on at least one surface is preferably 2 to 200 times higher than that inside, and more preferably 5 to 100 times higher than that inside. Furthermore, in the second and fourth embodiments of the polymer film according to the present disclosure, from the viewpoint of the dielectric loss tangent of the polymer film and adhesion to the metal layer, it is preferable that the concentration of the compound having the functional group on at least one surface is higher than that inside, more preferably that the concentration of the compound having the functional group on at least one surface is 2 to 200 times higher than that inside, and particularly preferably that the concentration of the compound having the functional group on at least one surface is 5 to 100 times higher than that inside.

[0018] The method for confirming the concentration of the compound having a functional group inside and on the surface of the polymer film in the present disclosure is as follows. The polymer film is cut with a microtome to prepare a cross-sectional sample in the thickness direction of the polymer film, and the cross-section is subjected to time-of-flight secondary ion mass spectrometry (TOF-SIMS, measuring device: TOF-SIMS V manufactured by ION-TOF) to measure the distribution of each component in the thickness direction of the polymer film.

[0019] Here, the surface of a polymer film refers to the outer surface of the polymer film (the surface in contact with air or a substrate), and in the present disclosure, the "surface" of a polymer film refers to the region from the outermost surface of the polymer film to a position that is 10% of the thickness of the polymer film when the thickness of the polymer film is 30 μm or less. When the thickness of the polymer film is more than 30 μm, the "surface" refers to the region from the outermost surface of the polymer film to a position that is 3 μm away in the thickness direction.

[0020] In the present disclosure, the "interior" of a polymer film refers to the region from the center of the polymer film in the thickness direction to a position corresponding to ±5% of the thickness of the polymer film when the thickness of the polymer film is 30 μm or less. When the thickness of the polymer film is more than 30 μm, the "interior" refers to the region from the center of the polymer film in the thickness direction to a position ±1.5 μm away in the thickness direction.

[0021] In the second and fourth embodiments of the polymer film according to the present disclosure, the surface coverage of the compound having the functional group on at least one surface of the polymer film is 50 area % or more, and from the viewpoints of the dielectric loss tangent of the polymer film and adhesion to the metal layer, it is preferable that the surface coverage of the compound having the functional group on at least one surface of the polymer film is 50 area % to 100 area %. In the first and third embodiments of the polymer film according to the present disclosure, from the viewpoints of the dielectric loss tangent of the polymer film and adhesion to the metal layer, the surface coverage of the compound having the functional group on at least one surface of the polymer film is preferably 50 area% or more, more preferably 50 area% to 100 area%, and even more preferably 80 area% to 100 area%.

[0022] The surface coverage of the compound having the functional group on the surface of the polymer film in the present disclosure is measured by the following method.

[0023] A polymer film not containing a compound having a functional group and a compound having a functional group are prepared. The contact angles of the polymer film not containing a compound having a functional group and the compound having a functional group are measured, and the surface energy is calculated from the contact angles. Similarly, the surface energy of the polymer film to be measured is calculated. A calibration curve is prepared using the surface energy of a polymer film that does not contain a compound having a functional group and the surface energy of a compound having a functional group. A polymer film that does not contain a compound having a functional group corresponds to a polymer film with a surface coverage of 0 area %, and a polymer film that contains a compound having a functional group corresponds to a polymer film with a surface coverage of 100 area %. From the created calibration curve, the surface coverage is calculated based on the surface energy of the polymer film to be measured. The surface energy can be calculated based on the contact angles measured by Owens' method after conditioning the sample at 25°C and 60% relative humidity for 24 hours, and then measuring the contact angles with water and methylene iodide. The contact angles can be measured using, for example, a DM901 contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.). When it is not possible to prepare a polymer film that does not contain a compound having a functional group, an imaging analysis of the surface of the polymer film can be performed to measure the coverage area of ​​fragments derived from the compound having a functional group, and the surface coverage rate can be calculated.

[0024] <Polymer with a dielectric loss tangent of 0.005 or less> The polymer film according to the present disclosure comprises a polymer having a dielectric loss tangent of 0.005 or less. A dielectric loss tangent of 0.005 or less indicates a small degree of electrical energy loss. From the viewpoint of the dielectric loss tangent of the polymer film and adhesion to the metal layer, the dielectric loss tangent of the polymer is preferably 0.004 or less, more preferably 0.0035 or less, and particularly preferably 0.003 or less. The lower limit of the dielectric loss tangent of the polymer is not particularly limited, but is, for example, greater than 0.

[0025] In the present disclosure, the dielectric loss tangent of a polymer is measured by identifying or isolating the chemical structure of the polymer constituting each layer, and using a powdered sample of the polymer to be measured, according to the dielectric loss tangent measurement method described below.

[0026] The dielectric loss tangent in the present disclosure is measured by the following method. The dielectric loss tangent is measured at a frequency of 10 GHz using the resonance perturbation method. A 1 GHz cavity resonator (Kanto Electronics Application Development Co., Ltd., model CP531) is connected to a network analyzer (Agilent Technology, model E8363B). A film sample (width: 2.0 mm x length: 80 mm) is inserted into the cavity resonator, and the dielectric loss tangent is measured from the change in resonance frequency before and after insertion for 96 hours in an environment with a temperature of 25°C and a humidity of 60%. When measuring the dielectric loss tangent of each layer contained in a polymer film, unnecessary layers may be scraped off with a razor or the like to prepare an evaluation sample containing only the target layer.

[0027] The weight-average molecular weight Mw of a polymer having a dielectric dissipation factor of 0.005 or less is preferably 1,000 or more, more preferably 2,000 or more, and particularly preferably 5,000 or more. The weight-average molecular weight Mw of a polymer having a dielectric dissipation factor of 0.005 or less is preferably 1,000,000 or less, more preferably 300,000 or less, and particularly preferably less than 100,000.

[0028] The melting point Tm or 5% mass loss temperature Td of a polymer having a dielectric dissipation factor of 0.005 or less is preferably 200° C. or higher, more preferably 250° C. or higher, even more preferably 280° C. or higher, and particularly preferably 300° C. or higher, from the viewpoints of the dielectric dissipation factor of the polymer film, adhesion to the metal layer, and heat resistance. The upper limit of Tm or Td is not particularly limited, and Tm or Td is, for example, 500° C. or lower, preferably 420° C. or lower. The melting point Tm in this disclosure is measured using a differential scanning calorimetry (DSC) device. The 5% mass loss temperature Td in this disclosure is measured using a thermogravimetric analyzer (TGA). Specifically, the weight of a sample placed in a measuring pan is set as an initial value, and the temperature at which the weight decreases by 5% by mass from the initial value due to heating is set as the 5% mass loss temperature Td.

[0029] The glass transition temperature Tg of a polymer having a dielectric dissipation factor of 0.005 or less is preferably 150° C. or more, and more preferably 200° C. or more, from the viewpoints of the dielectric dissipation factor of the polymer film, adhesion to a metal layer, and heat resistance. The upper limit of Tg is not particularly limited, and Tg is, for example, less than 350° C., preferably less than 280° C., and more preferably 280° C. or less. The glass transition temperature Tg in the present disclosure is measured using a differential scanning calorimetry (DSC) device.

[0030] In the present disclosure, the type of polymer having a dielectric loss tangent of 0.005 or less is not particularly limited, and any known polymer can be used. Examples of polymers having a dielectric dissipation factor of 0.005 or less include liquid crystal polymers, fluorine-based polymers, polymers of compounds having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond, thermoplastic resins such as polyether ether ketone, polyolefin, polyamide, polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyether sulfone, polyphenylene ether and modified products thereof, and polyether imide; elastomers such as copolymers of glycidyl methacrylate and polyethylene; and thermosetting resins such as phenol resins, epoxy resins, polyimide resins, and cyanate resins. Among these, the polymer having a dielectric dissipation factor of 0.005 or less is preferably at least one polymer selected from the group consisting of liquid crystal polymers, fluoropolymers, polymers of compounds having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond, and polyether ether ketone, from the viewpoints of the dielectric dissipation factor of the polymer film, adhesion to a metal layer, and heat resistance, and more preferably at least one polymer selected from the group consisting of liquid crystal polymers and fluoropolymers. From the viewpoint of the dielectric dissipation factor of the polymer film, liquid crystal polymers are particularly preferred, and from the viewpoints of heat resistance and mechanical strength, fluoropolymers are preferred.

[0031] -Liquid Crystal Polymer- The liquid crystal polymer contained in the polymer film of the present disclosure preferably has a dielectric loss tangent of 0.01 or less, and from the viewpoint of the dielectric loss tangent of the polymer film, it is preferable that the liquid crystal polymer has a dielectric loss tangent of 0.005 or less. In the present disclosure, the liquid crystal polymer used as the polymer having a dielectric loss tangent of 0.005 or less is not particularly limited in type, and any known liquid crystal polymer can be used as long as it has a dielectric loss tangent of 0.005 or less. 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. When the liquid crystal polymer is a thermotropic liquid crystal polymer, it is preferably a liquid crystal polymer that melts at a temperature of 450°C or less. Examples of the liquid crystal polymer include liquid crystal polyester, liquid crystal polyester amide in which an amide bond is introduced into liquid crystal polyester, liquid crystal polyester ether in which an ether bond is introduced into liquid crystal polyester, and liquid crystal polyester carbonate in which a carbonate bond is introduced into liquid crystal polyester. Furthermore, from the viewpoints of liquid crystallinity and linear expansion coefficient, the liquid crystal polymer is preferably a polymer having an aromatic ring, and more preferably an aromatic polyester or aromatic polyester amide. Furthermore, the liquid crystal polymer may be a polymer in which an imide bond, a carbodiimide bond, an isocyanate-derived bond such as an isocyanurate bond, or the like is further introduced into an aromatic polyester or an aromatic polyester amide. The liquid crystal polymer is preferably a wholly aromatic liquid crystal polymer made using only aromatic compounds as raw material monomers.

[0032] Examples of the liquid crystal polymer include the following liquid crystal polymers. 1) A compound obtained by polycondensation of (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 hydroxyamine, and an aromatic diamine. 2) A compound obtained by polycondensation of multiple types of aromatic hydroxycarboxylic acids. 3) (i) A compound obtained by polycondensation of an aromatic dicarboxylic acid and (ii) at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxyamine, and an aromatic diamine. 4) (i) Polyester such as polyethylene terephthalate and (ii) aromatic hydroxycarboxylic acid are polycondensed. Here, the aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, aromatic diol, aromatic hydroxyamine and aromatic diamine may each independently be replaced with a derivative capable of undergoing polycondensation.

[0033] For example, aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids can be replaced with aromatic hydroxycarboxylic acid esters and aromatic dicarboxylic acid esters by converting the carboxyl group to an alkoxycarbonyl group or an aryloxycarbonyl group. Aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids can be replaced with aromatic hydroxycarboxylic acid halides and aromatic dicarboxylic acid halides by converting the carboxy groups to haloformyl groups. Aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids can be replaced with aromatic hydroxycarboxylic acid anhydrides and aromatic dicarboxylic acid anhydrides by converting the carboxy groups to acyloxycarbonyl groups. Examples of polymerizable derivatives of compounds having a hydroxy group, such as aromatic hydroxycarboxylic acids, aromatic diols, and aromatic hydroxyamines, include those obtained by acylation of the hydroxy group to convert it into an acyloxy group (acylated products). For example, aromatic hydroxycarboxylic acids, aromatic diols, and aromatic hydroxyamines can be substituted with their acylated products by acylation of the hydroxy groups to convert them into acyloxy groups. Examples of polymerizable derivatives of compounds having an amino group, such as aromatic hydroxyamines and aromatic diamines, include those obtained by acylation of the amino group to convert it into an acylamino group (acylated product). For example, aromatic hydroxyamines and aromatic diamines can be substituted with their acylated products by acylation of the amino groups to convert them into acylamino groups.

[0034] From the viewpoints of liquid crystallinity, the dielectric loss tangent of the polymer film, and adhesion to a metal layer, the liquid crystal polymer preferably has a constitutional unit represented by any one of the following formulas (1) to (3), more preferably has a constitutional repeating unit represented by the following formula (1), and particularly preferably has a constitutional unit represented by the following formula (1), a constitutional repeating unit represented by the following formula (2), and a constitutional unit represented by the following formula (3). Hereinafter, the constitutional unit represented by formula (1) etc. will also be referred to as "unit (1)" etc. 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, a naphthylene group, or a biphenylylene group; Ar 2 and Ar 3 each independently represents a phenylene group, a naphthylene group, a biphenylylene group, or a group represented by the following formula (4), X and Y each independently represent an oxygen atom or an imino group, Ar 1 ~Ar 3 Each hydrogen atom in may be independently substituted with a halogen atom, an alkyl group, or an aryl group. Formula (4) -Ar 4 -Z-Ar 5 - In formula (4), Ar 4 and Ar 5 each independently represents 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.

[0035] The halogen atom includes a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, an n-hexyl group, a 2-ethylhexyl group, an n-octyl group, and an n-decyl group. The number of carbon atoms in the alkyl group is preferably 1 to 10. Examples of the aryl group include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 1-naphthyl group, and a 2-naphthyl group. The number of carbon atoms in the aryl group is preferably 6 to 20. Ar 1 ~Ar 3 When a hydrogen atom in the formula (I) is substituted with a halogen atom, an alkyl group, or an aryl group, the number of the substituents is each independently preferably 2 or less, more preferably 1.

[0036] Examples of the alkylene group include a methylene group, a 1,1-ethanediyl group, a 1-methyl-1,1-ethanediyl group, a 1,1-butanediyl group, and a 2-ethyl-1,1-hexanediyl group. The alkylene group preferably has 1 to 10 carbon atoms.

[0037] The unit (1) is a structural unit derived from an aromatic hydroxycarboxylic acid. Unit (1) is Ar 1 is a p-phenylene group (a structural unit derived from p-hydroxybenzoic acid), Ar 1 is preferably a 2,6-naphthylene group (a structural unit derived from 6-hydroxy-2-naphthoic acid) or a 4,4'-biphenylylene group (a structural unit derived from 4'-hydroxy-4-biphenylcarboxylic acid).

[0038] The unit (2) is a structural unit derived from an aromatic dicarboxylic acid. Unit (2) is Ar 2 is a p-phenylene group (a structural unit derived from terephthalic acid), Ar2 is an m-phenylene group (a structural unit derived from isophthalic acid), Ar 2 is a 2,6-naphthylene group (a structural unit derived from 2,6-naphthalenedicarboxylic acid), or Ar 2 is a diphenylether-4,4'-diyl group (a structural unit derived from diphenylether-4,4'-dicarboxylic acid).

[0039] The unit (3) is a structural unit derived from an aromatic diol, an aromatic hydroxylamine, or an aromatic diamine. Unit (3) is Ar 3 is a p-phenylene group (a structural unit derived from hydroquinone, p-aminophenol, or p-phenylenediamine), Ar 3 is an m-phenylene group (a structural unit derived from isophthalic acid), or Ar 3 is a 4,4'-biphenylylene group (a structural unit derived from 4,4'-dihydroxybiphenyl, 4-amino-4'-hydroxybiphenyl, or 4,4'-diaminobiphenyl).

[0040] The content of unit (1) is preferably 30 mol % or more, more preferably 30 mol % to 80 mol %, even more preferably 30 mol % to 60 mol %, and particularly preferably 30 mol % to 40 mol %, based on the total amount of all structural units. The content of the unit (2) is preferably 35 mol % or less, more preferably 10 mol % to 35 mol %, even more preferably 20 mol % to 35 mol %, and particularly preferably 30 mol % to 35 mol %, based on the total amount of all structural units. The content of the unit (3) is preferably 35 mol % or less, more preferably 10 mol % to 35 mol %, even more preferably 20 mol % to 35 mol %, and particularly preferably 30 mol % to 35 mol %, based on the total amount of all structural units. The greater the content of the unit (1), the more likely it is that the heat resistance, strength and rigidity will improve. However, if the content is too high, the solubility in solvents will tend to decrease. The total amount of all structural units is the sum of the amounts (moles) of each structural unit. The amount of each structural unit is calculated by dividing the mass of each structural unit constituting the liquid crystal polymer by the formula weight of that structural unit.

[0041] The ratio of the content of units (2) to the content of units (3), expressed as [content of units (2)] / [content of units (3)] (mol / mol), is preferably 0.9 / 1 to 1 / 0.9, more preferably 0.95 / 1 to 1 / 0.95, and even more preferably 0.98 / 1 to 1 / 0.98.

[0042] The liquid crystal polymer may independently have two or more types of units (1) to (3). The liquid crystal polymer may also have other structural units in addition to units (1) to (3). The content of other structural units is preferably 10 mol % or less, more preferably 5 mol % or less, based on the total amount of all structural units.

[0043] Because the liquid crystal polymer has excellent solubility in solvents, it preferably has units (3) in which at least one of X and Y is an imino group, that is, it preferably has at least one of a structural unit derived from an aromatic hydroxylamine and a structural unit derived from an aromatic diamine, and more preferably has only units (3) in which at least one of X and Y is an imino group.

[0044] The liquid crystal polymer is preferably produced by melt-polymerizing raw material monomers corresponding to the structural units constituting the liquid crystal polymer. The melt polymerization may be carried out in the presence of a catalyst. Examples of the catalyst include metal compounds such as magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, and antimony trioxide; and nitrogen-containing heterocyclic compounds such as 4-(dimethylamino)pyridine and 1-methylimidazole. The catalyst is preferably a nitrogen-containing heterocyclic compound. The melt polymerization may be further subjected to solid-state polymerization, if necessary.

[0045] The flow initiation temperature of the liquid crystal polymer is preferably 180° C. or higher, more preferably 200° C. or higher, and even more preferably 250° C. or higher. The flow initiation temperature is preferably 350° C. or lower, more preferably 330° C. or lower, and even more preferably 310° C. or lower. When the flow initiation temperature of the liquid crystal polymer is within the above range, the polymer has excellent solubility, heat resistance, strength, and rigidity, and the viscosity of the solution is appropriate.

[0046] The flow initiation temperature is also called the flow temperature or flow temperature, and is measured using a capillary rheometer at 9.8 MPa (100 kg / cm 2 When a liquid crystal polymer is melted and extruded through a nozzle with an inner diameter of 1 mm and a length of 10 mm while heating at a rate of 4°C / min under a load of 1000 kJ / s, the temperature at which the polymer shows a viscosity of 4,800 Pa·s (48,000 poise) is measured. This temperature is an indicator of the molecular weight of liquid crystal polyester (see "Liquid Crystal Polymer - Synthesis, Molding, and Applications," edited by Naoyuki Koide, CMC Corporation, June 5, 1987, p. 95).

[0047] The weight-average molecular weight of the liquid crystal polymer is preferably 1,000,000 or less, more preferably 3,000 to 300,000, even more preferably 5,000 to 100,000, and particularly preferably 5,000 to 30,000. When the weight-average molecular weight of the liquid crystal polymer is within the above range, the film after heat treatment will have excellent thermal conductivity in the thickness direction, heat resistance, strength, and rigidity.

[0048] -Fluorine-based polymer- The polymer having a dielectric loss tangent of 0.005 or less is preferably a fluorine-based polymer from the viewpoints of heat resistance and mechanical strength. In the present disclosure, the fluoropolymer used as the polymer having a dielectric dissipation factor of 0.005 or less is not particularly limited to a particular type, and any known fluoropolymer can be used, as long as it has a dielectric dissipation factor of 0.005 or less.

[0049] Examples of fluorine-based polymers include homopolymers and copolymers containing structural units derived from fluorinated α-olefin monomers, i.e., α-olefin monomers containing at least one fluorine atom, and copolymers containing structural units derived from fluorinated α-olefin monomers and structural units derived from non-fluorinated ethylenically unsaturated monomers reactive with the fluorinated α-olefin monomers.

[0050] Fluorinated α-olefin monomers include CF2=CF2, CHF=CF2, CH2=CF2, CHCl=CHF, CClF=CF2, CCl2=CF2, CClF=CClF, CHF=CCl2, CH2=CClF, CCl2=CClF, CF3CF=CF2, CF3CF=CHF, CF3CH=CF2, CF3CH=CH2, CHF2CH=CHF, CF3CF=CF2, and perfluoro(alkyl having 2 to 8 carbon atoms)vinyl ethers (e.g., perfluoromethyl vinyl ether, perfluoropropyl vinyl ether, and perfluorooctyl vinyl ether). Among them, the fluorinated α-olefin monomer is preferably at least one monomer selected from the group consisting of tetrafluoroethylene (CF2=CF2), chlorotrifluoroethylene (CClF=CF2), (perfluorobutyl)ethylene, vinylidene fluoride (CH2=CF2), and hexafluoropropylene (CF2=CFCF3). Non-fluorinated ethylenically unsaturated monomers include ethylene, propylene, butene, ethylenically unsaturated aromatic monomers (eg, styrene and α-methylstyrene), and the like. The fluorinated α-olefin monomers may be used alone or in combination of two or more. The non-fluorinated ethylenically unsaturated monomers may be used alone or in combination of two or more.

[0051] Examples of fluorine-based polymers include polychlorotrifluoroethylene (PCTFE), poly(chlorotrifluoroethylene-propylene), poly(ethylene-tetrafluoroethylene) (ETFE), poly(ethylene-chlorotrifluoroethylene) (ECTFE), poly(hexafluoropropylene), poly(tetrafluoroethylene) (PTFE), poly(tetrafluoroethylene-ethylene-propylene), poly(tetrafluoroethylene-hexafluoropropylene) (FEP), poly(tetrafluoroethylene-propylene) (FEPM), poly(tetrafluoroethylene-perfluoropropylene vinyl ether), poly(tetrafluoroethylene-perfluoroalkyl vinyl ether) (PFA) (e.g., poly(tetrafluoroethylene-perfluoropropyl vinyl ether), polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-chlorotrifluoroethylene), perfluoropolyether, perfluorosulfonic acid, and perfluoropolyoxetane.

[0052] The fluorine-based polymer may have structural units derived from fluorinated ethylene or fluorinated propylene. The fluorine-based polymers may be used alone or in combination of two or more.

[0053] The fluorine-based polymer is preferably FEP, PFA, ETFE, or PTFE. FEP is available from DuPont under the trade name TEFLON FEP, or from Daikin Industries, Ltd. under the trade name NEOFLON FEP. PFA is available from Daikin Industries, Ltd. under the trade name NEOFLON PFA, from DuPont under the trade name TEFLON PFA, or from Solvay Solexis under the trade name HYFLON PFA.

[0054] The fluoropolymer more preferably includes PTFE. The PTFE may be a PTFE homopolymer, a partially modified PTFE homopolymer, or a combination including one or both of these. The partially modified PTFE homopolymer preferably contains less than 1% by mass of structural units derived from comonomers other than tetrafluoroethylene, based on the total mass of the polymer.

[0055] The fluorine-based polymer may be a crosslinkable fluoropolymer having a crosslinkable group. The crosslinkable fluoropolymer can be crosslinked by a conventionally known crosslinking method. One of the representative crosslinkable fluoropolymers is a fluoropolymer having a (meth)acryloyloxy group. For example, the crosslinkable fluoropolymer has the formula: H2C=CR'COO-(CH2) n -R-(CH2) n -OOCR'=CH2 In the formula, R is an oligomer chain containing a structural unit derived from a fluorinated α-olefin monomer, R' is H or —CH3, and n is 1 to 4. R may also be a fluorine-based oligomer chain containing a structural unit derived from tetrafluoroethylene.

[0056] A crosslinked fluoropolymer network can be formed by exposing a fluoropolymer having (meth)acryloyloxy groups to a free radical source to initiate a radical crosslinking reaction via the (meth)acryloyloxy groups on the fluoropolymer. The free radical source is not particularly limited, but suitable examples include a photoradical polymerization initiator or an organic peroxide. Suitable photoradical polymerization initiators and organic peroxides are well known in the art. Crosslinkable fluoropolymers are commercially available, for example, Viton B manufactured by DuPont.

[0057] -Polymer of a compound having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond- The polymer having a dielectric loss tangent of 0.005 or less may be a polymer of a compound having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond.

[0058] Examples of polymers of compounds having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond include thermoplastic resins having structural units derived from cyclic olefin monomers such as norbornene or polycyclic norbornene monomers. The polymer of a compound having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond may be a ring-opening polymer of the above-mentioned cyclic olefin, a hydrogenated product of a ring-opening copolymer using two or more kinds of cyclic olefins, or an addition polymer of a cyclic olefin and an aromatic compound having an ethylenically unsaturated bond such as a chain olefin or a vinyl group. In addition, a polar group may be introduced into the polymer of a compound having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond. The polymer of a compound having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond may be used alone or in combination of two or more kinds.

[0059] The ring structure of the cyclic aliphatic hydrocarbon group may be a monocyclic ring, a fused ring in which two or more rings are fused, or a bridged ring. Examples of the ring structure of the cycloaliphatic hydrocarbon group include a cyclopentane ring, a cyclohexane ring, a cyclooctane ring, an isophorone ring, a norbornane ring, and a dicyclopentane ring. The compound having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond may be a monofunctional ethylenically unsaturated compound or a polyfunctional ethylenically unsaturated compound. The number of alicyclic hydrocarbon groups in the compound having a alicyclic hydrocarbon group and a group having an ethylenically unsaturated bond may be one or more, and may be two or more. The polymer of a compound having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond may be a polymer obtained by polymerizing at least one compound having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond, and may be a polymer of a compound having two or more types of cyclic aliphatic hydrocarbon groups and a group having an ethylenically unsaturated bond, or may be a copolymer with another ethylenically unsaturated compound that does not have a cyclic aliphatic hydrocarbon group. The polymer of a compound having a cyclic aliphatic hydrocarbon group and a group having an ethylenically unsaturated bond is preferably a cycloolefin polymer.

[0060] -Polyether ether ketone- The polymer having a dielectric loss tangent of 0.005 or less may be polyetheretherketone. Polyether ether ketone is a type of aromatic polyether ketone, and is a polymer in which bonds are arranged in the following order: ether bond, ether bond, and carbonyl bond (ketone). Each bond is preferably connected by a divalent aromatic group. In the present disclosure, the polyether ether ketone used as the polymer having a dielectric dissipation factor of 0.005 or less is not particularly limited to a particular type as long as it has a dielectric dissipation factor of 0.005 or less, and any known polyether ether ketone can be used.

[0061] The polymer having a dielectric loss tangent of 0.005 or less is preferably a polymer that is soluble in a specific organic solvent (hereinafter also referred to as a "soluble polymer"). Specifically, the soluble polymer in the present disclosure is a polymer that dissolves in an amount of 0.1 g or more at 25°C in 100 g of at least one solvent selected from the group consisting of N-methylpyrrolidone, N-ethylpyrrolidone, dichloromethane, dichloroethane, chloroform, N-methyl-2-pyrrolidone, N,N-dimethylacetamide, γ-butyrolactone, dimethylformamide, ethylene glycol monobutyl ether, and ethylene glycol monoethyl ether.

[0062] The polymer film may contain only one type of polymer having a dielectric loss tangent of 0.005 or less, or may contain two or more types of polymers. The content of the polymer having a dielectric loss tangent of 0.005 or less in the polymer film is preferably 20% by mass to 99% by mass, more preferably 30% by mass to 98% by mass, even more preferably 40% by mass to 97% by mass, and particularly preferably 50% by mass to 95% by mass, relative to the total mass of the polymer film, from the viewpoints of the dielectric loss tangent of the polymer film and adhesion to the metal layer.

[0063] <Compounds with functional groups> The polymer film according to the present disclosure comprises a compound having a functional group. In the first and second embodiments, the compound having a functional group in the present disclosure is a compound other than the polymer having a dielectric loss tangent of 0.005 or less. In the third and fourth embodiments, the compound having a functional group in the present disclosure is a compound other than the liquid crystal polymer.

[0064] The compound having a functional group may be any of a low molecular weight compound, an oligomer, and a polymer, but from the viewpoint of mechanical strength, an oligomer or a polymer is preferable, and a polymer is more preferable. For example, the polymer film according to the present disclosure may contain a polymer having a functional group as the compound having a functional group. In the present disclosure, an oligomer is a polymer having a weight-average molecular weight of less than 2,000, and a polymer is a polymer having a weight-average molecular weight of 2,000 or more. The functional group is preferably a group capable of interacting with a group present on a metal or on a metal surface. The functional group is preferably at least one type of group selected from the group consisting of a group capable of forming a covalent bond, a group capable of forming an ionic bond, a group capable of forming a hydrogen bond, and a group capable of forming a dipole-dipole interaction. The compound having a functional group is preferably a low molecular weight compound from the viewpoints of compatibility between the polymer or liquid crystal polymer having a dielectric dissipation factor of 0.005 or less and the compound having a functional group, and the dielectric dissipation factor of the polymer film, and is preferably an oligomer or a polymer from the viewpoints of the heat resistance, mechanical strength, and surface unevenness of the polymer film. The compound having a functional group preferably interacts with or becomes entangled with the matrix material (e.g., a polymer with a dielectric loss tangent of 0.005 or less) contained in the polymer film. Entanglement can occur when the compound having a functional group and the matrix material mix at the molecular level, increasing the coefficient of friction; when the continuous phase of the compound having a functional group and the continuous phase of the matrix material interpenetrate; or when a mechanical bond is formed due to the surface shape of each material (anchor effect). In the case where the compound having a functional group and the matrix material interpenetrate each other, it is preferable that the compound having a functional group is a compound that undergoes phase separation from the matrix material, or a compound that undergoes phase separation from the matrix material due to bonding between compounds having functional groups. The number of functional groups in the compound having functional groups may be one or more, and may be two or more. Furthermore, the compound having a functional group may have only one type of functional group, or may have two or more types of functional groups. In particular, the number of functional groups in the compound having functional groups is preferably 2 or more. As the number of functional groups increases, the electrical properties tend to deteriorate, so the number of functional groups is preferably 10 or less.

[0065] From the viewpoint of adhesion to the metal layer, the molecular weight of the low molecular weight compound used as the compound having a functional group is preferably 50 or more and less than 2,000, more preferably 100 or more and less than 1,000, and particularly preferably 200 or more and less than 1,000. Furthermore, the weight-average molecular weight of the polymer compound (oligomer, polymer) used as the compound having a functional group is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more and 200,000 or less, and particularly preferably 5,000 or more and 100,000 or less, from the viewpoints of adhesion to the metal layer and uneven distribution on the surface.

[0066] Furthermore, from the viewpoint of the dielectric tangent of the polymer film and adhesion to the metal layer, the compound having a functional group is preferably an acrylic resin having a functional group, and more preferably an acrylic copolymer obtained by polymerizing at least a (meth)acrylate compound having a functional group. Furthermore, from the viewpoints of surface uneven distribution and adhesion to the metal layer, the acrylic resin having the above functional group preferably has a perfluoroalkyl group having 4 or more carbon atoms, more preferably has a perfluoroalkyl group having 4 to 30 carbon atoms, and particularly preferably has a perfluoroalkyl group having 5 to 20 carbon atoms. Furthermore, from the viewpoints of surface uneven distribution and adhesion to the metal layer, the compound having a functional group preferably contains a silicon atom or a fluorine atom, is more preferably a silicone resin having a functional group or a fluorine-based resin having a functional group, and is particularly preferably a silicone resin having a functional group.

[0067] Furthermore, from the viewpoint of the dielectric loss tangent of the polymer film and adhesion to the metal layer, the compound having a functional group may be a compound that is compatible with a polymer or liquid crystal polymer having a dielectric loss tangent of 0.005 or less, or may be a compound that is not compatible with the polymer or liquid crystal polymer, but is preferably a compatible compound. Whether a compound having a functional group is compatible with a polymer or liquid crystal polymer having a dielectric loss tangent of 0.005 or less can be determined by the difference in SP value. The difference between the SP value by the Hoy method of a polymer or liquid crystal polymer having a dielectric dissipation factor of 0.005 or less and the SP value by the Hoy method of a compound having a functional group is 5 MPa in view of the compatibility between the polymer or liquid crystal polymer having a dielectric dissipation factor of 0.005 or less and the compound having a functional group, the dielectric dissipation factor of the polymer film, and the adhesion to the metal layer. 0.5 The lower limit of the difference is preferably 0 MPa or less. 0.5 The difference in SP value is 5 MPa. 0.5 When it is equal to or less than 0.005, the compound having a functional group and the liquid crystal polymer have a dielectric loss tangent of 0.005 or less, and are compatible with each other.

[0068] Furthermore, from the viewpoint of uneven distribution on the surface and adhesion to the metal layer, the compound having a functional group may be a compound that is incompatible with a polymer having a dielectric loss tangent of 0.005 or less or a liquid crystal polymer. The difference between the SP value by the Hoy method of a polymer or liquid crystal polymer with a dielectric dissipation factor of 0.005 or less and the SP value by the Hoy method of a compound having a functional group is 5 MPa from the viewpoint of surface uneven distribution and adhesion with a metal layer. 0.5 The upper limit of the difference is not particularly limited, but it is preferably 50 MPa. 0.5 is.

[0069] The SP value (solubility parameter value) according to the Hoy method is calculated from the molecular structure using the method described in the Polymer Handbook, fourth edition. If the resin is a mixture of multiple resins, the SP value is calculated for each constituent unit.

[0070] [Functional group] The functional group in the compound having a functional group is preferably at least one type of group selected from the group consisting of a group capable of forming a covalent bond, a group capable of forming an ionic bond, a group capable of forming a hydrogen bond, and a group capable of forming a dipole-dipole interaction. From the viewpoint of adhesion to the metal layer, the functional group is preferably a group capable of forming a covalent bond. From the viewpoint of storage stability and ease of handling, the functional group is preferably a group capable of forming an ionic bond, a group capable of forming a hydrogen bond, or a group capable of dipole-dipole interaction.

[0071] -Covalently bondable group- The covalently bondable group is not particularly limited as long as it is a group capable of forming a covalent bond, and examples thereof include an epoxy group, an oxetanyl group, an isocyanate group, an acid anhydride group, a carbodiimide group, an N-hydroxyester group, a glyoxal group, an imide ester group, a halogenated alkyl group, a thiol group, a hydroxy group, a carboxy group, an amino group, an amide group, an aldehyde group, a sulfonic acid group, etc. Among these, from the viewpoint of adhesion to the metal layer, the covalently bondable group is preferably at least one functional group selected from the group consisting 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 imide ester group, a halogenated alkyl group, and a thiol group, and an epoxy group is particularly preferred.

[0072] As will be described later, the metal to be attached to the polymer film preferably has, on its surface, a group that pairs with the functional group of the compound having a functional group. A specific example of a combination of a covalently bondable group and a group that pairs with the covalently bondable group (a combination of a functional group of a compound having a functional group contained in a polymer film and a group possessed by a metal) is a combination in which one is an epoxy group and the other is a hydroxy group or an amino group. Furthermore, examples of combinations of a covalently bondable group and a group that pairs with the covalently bondable group include combinations in which one is, for example, an N-hydroxyester group or an imide ester group and the other is an amino group.

[0073] -Ionic bonding capable group- Examples of the group capable of forming an ionic bond include a cationic group and an anionic group. The cationic group is preferably an onium group. Examples of the onium group include an ammonium group, a pyridinium group, a phosphonium group, an oxonium group, a sulfonium group, a selenonium group, and an iodonium group. Among these, from the viewpoint of adhesion to the metal layer, the group capable of forming an ionic bond is preferably an ammonium group, a pyridinium group, a phosphonium group, or a sulfonium group, more preferably an ammonium group or a phosphonium group, and particularly preferably an ammonium group. The anionic group is not particularly limited and examples thereof include a phenolic hydroxyl group, a carboxy group, -SO3H, -OSO3H, -PO3H, -OPO3H2, -CONHSO2-, -SONHSO2-, etc. Among these, the anionic group is preferably a phosphate group, a phosphonate group, a phosphinate group, a sulfate group, a sulfonic acid group, a sulfinic acid group, or a carboxy group, more preferably a phosphate group or a carboxy group, and even more preferably a carboxy group.

[0074] A specific example of a combination of a group capable of forming an ionic bond and a group that pairs with the group capable of forming an ionic bond (a combination of a functional group of a compound having a functional group contained in a polymer film and a group possessed by a metal) is a combination in which one is an acidic group and the other is a basic group. Examples of the acidic group include a carboxy group, a sulfo group, and a phosphate group, with a carboxy group being preferred. When one of the groups is, for example, a carboxy group, examples of the group capable of forming an ionic bond with the carboxy group include a tertiary amino group, a pyridyl group, and a piperidyl group.

[0075] -Hydrogen-bonding groups- Examples of groups capable of forming hydrogen bonds include groups having a hydrogen bond donating site and groups having a hydrogen bond accepting site. The hydrogen bond donor site may be any structure having an active hydrogen atom capable of forming a hydrogen bond, but is preferably a structure represented by XH. X represents a heteroatom, and is preferably a nitrogen atom or an oxygen atom. From the viewpoint of adhesion to the metal layer, the hydrogen bond donor moiety is preferably at least one structure selected from the group consisting of a hydroxy group, a carboxy group, a primary amide group, a secondary amide group, a primary amino group, a secondary amino group, a primary sulfonamide group, a secondary sulfonamide group, an imide group, a urea bond, and a urethane bond; more preferably at least one structure selected from the group consisting of a hydroxy group, a carboxy group, a primary amide group, a secondary amide group, a primary sulfonamide group, a secondary sulfonamide group, a maleimide group, a urea bond, and a urethane bond; still more preferably at least one structure selected from the group consisting of a hydroxy group, a carboxy group, a primary amide group, a secondary amide group, a primary sulfonamide group, a secondary sulfonamide group, and a maleimide group; and particularly preferably at least one structure selected from the group consisting of a hydroxy group and a secondary amide group.

[0076] The hydrogen bond accepting site is preferably a structure containing an atom having an unshared electron pair, more preferably a structure containing an oxygen atom having an unshared electron pair, further preferably at least one structure selected from the group consisting of a carbonyl group (including carbonyl structures such as a carboxy group, an amide group, an imide group, a urea bond, and a urethane bond) and a sulfonyl group (including sulfonyl structures such as a sulfonamide group), and particularly preferably a carbonyl group (including carbonyl structures such as a carboxy group, an amide group, an imide group, a urea bond, and a urethane bond).

[0077] The group capable of forming a hydrogen bond is preferably a group having both the above-mentioned hydrogen bond donor site and hydrogen bond acceptor site, and preferably has a carboxy group, an amide group, an imide group, a urea bond, a urethane bond, or a sulfonamide group, and more preferably has a carboxy group, an amide group, an imide group, or a sulfonamide group.

[0078] Specific examples of combinations of a group capable of forming a hydrogen bond and a group that pairs with the group capable of forming a hydrogen bond (combinations of a functional group of a compound having a functional group and a group on the surface of a metal) include combinations in which one is a group having a hydrogen bond donor site and the other is a group having a hydrogen bond acceptor site. For example, when one is a carboxy group, the other may be an amide group, a carboxy group, or the like. Furthermore, examples of combinations of a group capable of forming a hydrogen bond and a group that pairs with the group capable of forming a hydrogen bond include combinations in which one is a phenolic hydroxyl group and the other is a phenolic hydroxyl group.

[0079] -Group capable of dipole-dipole interaction- The group capable of dipole-dipole interaction may be any group having a polarized structure other than the structure represented by XH (X represents a heteroatom) in the above-mentioned groups capable of hydrogen bonding, and a preferred example is a group in which atoms with different electronegativities are bonded to each other. As a combination of atoms having different electronegativities, a combination of at least one atom selected from the group consisting of oxygen atoms, nitrogen atoms, sulfur atoms, and halogen atoms and carbon atoms is preferred, and a combination of at least one atom selected from the group consisting of oxygen atoms, nitrogen atoms, and sulfur atoms and carbon atoms is more preferred. Among these, from the viewpoint of adhesion to the metal layer, a combination of a nitrogen atom and a carbon atom, and a combination of a carbon atom with a nitrogen atom, an oxygen atom, and a sulfur atom are preferred, and specifically, a cyano group, a cyanuric group, and a sulfonic acid amide group are more preferred.

[0080] As a combination of a group capable of dipole-dipole interaction and a group that pairs with the group capable of dipole-dipole interaction (a combination of a functional group of a compound having a functional group and a group on the surface of a metal), a combination of the same groups capable of dipole-dipole interaction is preferably used. Examples of combinations of a group capable of dipole-dipole interaction and a group pairing with the group capable of dipole-dipole interaction include combinations in which one is, for example, a cyano group and the other is also a cyano group. Furthermore, examples of combinations of a group capable of dipole-dipole interaction and a group pairing with the group capable of dipole-dipole interaction include a combination in which one is, for example, a sulfonic acid amide group and the other is a sulfonic acid amide group.

[0081] Specifically, the functional group in the compound having a functional group preferably includes at least one selected from the group consisting 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 imide ester group, a halogenated alkyl group, a thiol group, a hydroxy group, a carboxy group, an amino group, an amide group, an isocyanate group, an aldehyde group, a sulfonic acid group, an ammonium group, a pyridinium group, a phosphonium group, an oxonium group, a sulfonium group, a selenonium group, an iodonium group, a phosphate group, a phosphonic acid group, a phosphinic acid group, a sulfate group, a sulfonic acid group, a sulfinic acid group, or a carboxy group, a hydroxy group, a carboxy group, a primary amide group, a secondary amide group, a primary amino group, a secondary amino group, a primary sulfonamide group, a secondary sulfonamide group, an imide group, a urea bond, and a urethane bond. From the viewpoint of improving adhesion, the functional group in the compound having a functional group is more preferably an epoxy group, an oxetanyl group, an isocyanate group, an acid anhydride group, a carbodiimide group, an N-hydroxyester group, a glyoxal group, an imide ester group, a halogenated alkyl group, or a thiol group.

[0082] Specific examples of bonds or interactions between two types of functional groups are shown below, but the above bonds or interactions in the present disclosure are not limited thereto.

[0083] [ka]

[0084] From the viewpoints of the dielectric tangent of the polymer film and adhesion to the metal layer, the compound having a functional group is preferably a polymer having a functional group, and more preferably an acrylic resin having a functional group or a silicone resin having a functional group. In addition, from the viewpoint of the dielectric loss tangent of the polymer film and adhesion to the metal layer, the compound having a functional group preferably contains a liquid crystal polymer obtained by polymerizing a liquid crystal polymer precursor having a polymerizable group.

[0085] The polymer film may contain only one type of compound having a functional group, or may contain two or more types of compounds having a functional group. From the viewpoints of the dielectric loss tangent of the polymer film and adhesion to the metal layer, the content of the compound having a functional group in the polymer film is preferably 0.05% by mass to 50% by mass, more preferably 0.1% by mass to 30% by mass, even more preferably 0.2% by mass to 10% by mass, and particularly preferably 0.5% by mass to 5% by mass, relative to the total mass of the polymer film.

[0086] <Third component and immobilization> From the viewpoints of the dielectric loss tangent of the polymer film, adhesion to a metal layer, heat resistance, and mechanical strength, it is preferable that the polymer film according to the present disclosure further contains a third component that fixes the compound having the functional group to the polymer or liquid crystal polymer having a dielectric loss tangent of 0.005 or less. The third component is preferably a compound other than the polymer or liquid crystal polymer having a dielectric loss tangent of 0.005 or less, and the compound having the functional group. Preferred examples of the means for immobilizing the compound having the functional group on the polymer or liquid crystal polymer having a dielectric dissipation factor of 0.005 or less include a means for forming a three-dimensional crosslinked structure in a polymer film and immobilizing the compound, or a means for immobilizing the compound by using a polymer that has a functional group that interacts with the compound having the functional group and is compatible with the polymer or liquid crystal polymer having a dielectric dissipation factor of 0.005 or less, and utilizing entanglement between the polymers.

[0087] The polymer film according to the present disclosure preferably has a three-dimensional crosslinked structure from the viewpoints of the dielectric loss tangent of the polymer film, adhesion to the metal layer, heat resistance, and mechanical strength. As a method for forming a three-dimensional crosslinked structure, a method of polymerizing a polyfunctional reactive compound (for example, a polyfunctional monomer) to form a cured product of the polyfunctional reactive compound can be mentioned. That is, from the viewpoints of the dielectric loss tangent of the polymer film, adhesion to the metal layer, heat resistance, and mechanical strength, the third component preferably contains a cured product of a polyfunctional reactive compound, and more preferably contains a cured product of a polyfunctional (meth)acrylate compound. Here, the cured product of a polyfunctional reactive compound refers to a compound in which the reactive groups of the polyfunctional reactive compound have substantially lost their reactivity due to various curing reactions such as crosslinking and polymerization. That is, some of the reactive groups of the polyfunctional reactive compound may remain unreacted; for example, it is sufficient that 50% or more of all the reactive groups of the polyfunctional reactive compound have disappeared. The proportion of the reactive groups of the polyfunctional reactive compound that have disappeared is preferably 80% or more, more preferably 90% or more, and even more preferably 100% (i.e., a state in which all the reactive groups of the polyfunctional reactive compound have disappeared). The degree of disappearance of the reactive groups can be measured by known methods, such as a method in which a cured product of the polyfunctional reactive compound contained in a polymer film is identified and measured by infrared absorption spectroscopy or the like.

[0088] The cured product of the polyfunctional reactive compound may be a homopolymer of the polyfunctional reactive compound, a copolymer of two or more polyfunctional reactive compounds, or a copolymer of one or more polyfunctional reactive compounds and one or more monofunctional reactive compounds (monofunctional monomers). The cured product of the polyfunctional reactive compound is not particularly limited, but is preferably an addition polymerization resin. As the polyfunctional reactive compound, known polyfunctional monomers can be used, and polyfunctional ethylenically unsaturated compounds are preferred. Examples of the polyfunctional ethylenically unsaturated compound include a polyfunctional (meth)acrylate compound, a polyfunctional (meth)acrylamide compound, a polyfunctional vinyl compound, a polyfunctional styrene compound, and a mixture thereof. Among them, the polyfunctional ethylenically unsaturated compound is preferably a polyfunctional (meth)acrylate compound. Furthermore, the cured product of the polyfunctional reactive compound may be copolymerized with a monofunctional reactive compound in order to adjust the size of the network of the three-dimensional crosslinked structure. Furthermore, it is preferable to use a polymerization initiator to form a cured product of the polyfunctional reactive compound. As the polymerization initiator, a known photopolymerization initiator, a known thermal polymerization initiator, etc. can be used. Among them, the polymerization initiator is preferably a photopolymerization initiator. Furthermore, from the viewpoints of the dielectric loss tangent of the polymer film, adhesion to the metal layer, heat resistance, and mechanical strength, the polymer film according to the present disclosure preferably contains a liquid crystal polymer precursor as a polyfunctional reactive compound. The liquid crystal polymer precursor is not particularly limited as long as it is a polymerizable liquid crystal polymer. The liquid crystal polymer precursor may be one in which a polymerizable group has been generated by a predetermined treatment (e.g., annealing treatment, surface treatment such as plasma) during the production of a polymer film, or the liquid crystal polymer precursor itself may have a polymerizable group.

[0089] From the viewpoints of the dielectric loss tangent of the polymer film, adhesion to a metal layer, heat resistance, and mechanical strength, the polymer film according to the present disclosure preferably contains, as a third component, a compound having a functional group that interacts with the compound having the functional group and that is compatible with a polymer or liquid crystal polymer having a dielectric loss tangent of 0.005 or less, more preferably a polymer having a functional group that interacts with the compound having the functional group and that is compatible with a polymer or liquid crystal polymer having a dielectric loss tangent of 0.005 or less, and particularly preferably a liquid crystal polymer having a functional group that interacts with the compound having the functional group and that is compatible with a polymer or liquid crystal polymer having a dielectric loss tangent of 0.005 or less. A preferred embodiment of the functional group possessed by the compound having a functional group that interacts with the above-mentioned compound having a functional group and that is compatible with the polymer or liquid crystal polymer having a dielectric dissipation factor of 0.005 or less is the same as the functional group of the above-mentioned compound having a functional group, except that the functional group is a pair with the functional group in the above-mentioned compound having a functional group. For example, when the functional group in the above-mentioned compound having a functional group is an epoxy group, preferred examples of the functional group in the third component include an amino group, a hydroxy group, etc. The difference between the SP value by the Hoy method of a polymer or liquid crystal polymer having a dielectric dissipation factor of 0.005 or less and the SP value by the Hoy method of a compound having a functional group that interacts with the compound having the functional group and that is compatible with the polymer or liquid crystal polymer having a dielectric dissipation factor of 0.005 or less is 5 MPa from the viewpoints of compatibility, the dielectric dissipation factor of the polymer film, and adhesion to the metal layer. 0.5 The lower limit of the difference is preferably 0 MPa or less. 0.5 is.

[0090] The method for measuring the SP value by the Hoy method is as described above. Whether or not the third component is compatible with a polymer having a dielectric loss tangent of 0.005 or less can be determined by the difference in SP value. 0.5 When the dielectric loss tangent is 0.005 or less, the third component and the polymer having the dielectric loss tangent of 0.005 or less are compatible with each other.

[0091] The polymer film may contain only one type of third component, or may contain two or more types. From the viewpoints of the dielectric loss tangent of the polymer film and adhesion to the metal layer, the content of the third component in the polymer film is preferably 1% by mass to 80% by mass, more preferably 2% by mass to 70% by mass, even more preferably 3% by mass to 60% by mass, and particularly preferably 5% by mass to 55% by mass, relative to the total mass of the polymer film.

[0092] <Filler> The polymer film preferably contains a filler from the viewpoints of the linear expansion coefficient and adhesion to the metal layer. The filler may be particulate or fibrous, and may be an inorganic filler or an organic filler. In the polymer film according to the present disclosure, the number density of the filler is preferably greater inside than on the surface of the polymer film, from the viewpoints of the linear expansion coefficient and adhesion to the metal layer.

[0093] The number density of the filler is measured by the following method. The film is cut with a microtome to prepare a cross-sectional sample. The cross-sectional sample is observed under a scanning electron microscope (approximately 100x to 300x magnification). The total observation area is 0.5 mm 2 Observe at least three places to ensure that the 2 The average number of fillers per unit area is calculated.

[0094] As the inorganic filler, known inorganic fillers can be used. Examples of inorganic filler materials include BN, Al2O3, AlN, TiO2, SiO2, barium titanate, strontium titanate, aluminum hydroxide, calcium carbonate, and materials containing two or more of these. Among these, as the inorganic filler, from the viewpoint of adhesion to the metal layer, metal oxide particles or fibers are preferred, silica particles, titania particles or glass fibers are more preferred, and silica particles or glass fibers are particularly preferred. The average particle size of the inorganic filler is preferably about 20% to about 40% of the thickness of Layer A, and may be, for example, 25%, 30%, or 35% of the thickness of Layer A. When the particles or fibers are flat, this refers to the length in the direction of the short side. From the viewpoint of adhesion to the metal layer, 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 particularly preferably 25 nm to 500 nm.

[0095] As the organic filler, known organic fillers can be used. Examples of materials for the organic filler include polyethylene, polystyrene, urea resin, polyester, cellulose, acrylic resin, fluororesin, hardened epoxy resin, crosslinked benzoguanamine resin, crosslinked acrylic resin, liquid crystal polymer, and materials containing two or more of these. The organic filler may be in the form of fibers such as nanofibers, or may be hollow resin particles. Among these, from the viewpoints of the thermal expansion coefficient and adhesion to the metal layer, the organic filler is preferably fluororesin particles, polyester-based resin particles, polyethylene particles, liquid crystal polymer particles, or nanofibers of cellulose-based resin, and more preferably polytetrafluoroethylene particles, polyethylene particles, or liquid crystal polymer particles. Here, the liquid crystal polymer particles can be produced, for example, by polymerizing a liquid crystal polymer and pulverizing it into powder using a pulverizer, etc. The average particle size of the liquid crystal polymer particles is preferably smaller than the thickness of each layer.

[0096] From the viewpoints of the thermal expansion coefficient and adhesion to the metal layer, 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, and particularly preferably 25 nm to 90 nm.

[0097] The polymer film may contain only one type of filler, or may contain two or more types of fillers. From the viewpoint of adhesion to the metal layer, the content of the filler in the polymer film is preferably 5% by volume to 80% by volume, more preferably 10% by volume to 70% by volume, even more preferably 15% by volume to 70% by volume, and particularly preferably 20% by volume to 60% by volume, relative to the total volume of the polymer film.

[0098] -Other additives- The polymer film may contain other additives in addition to the components described above. As other additives, known additives can be used, such as leveling agents, antifoaming agents, antioxidants, ultraviolet absorbers, flame retardants, and colorants.

[0099] The polymer film may also contain other additives such as polymers having a dielectric loss tangent of 0.005 or less, liquid crystal polymers, and resins other than the compounds having functional groups. Examples of other resins include thermoplastic resins such as polypropylene, polyamide, polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyether sulfone, polyphenylene ether and modified products thereof, and polyether imide; elastomers such as copolymers of glycidyl methacrylate and polyethylene; and thermosetting resins such as phenolic resins, epoxy resins, polyimide resins, and cyanate resins.

[0100] The total content of other additives in the polymer film is preferably 25 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the polymer having a dielectric tangent of 0.005 or less. The total content of other additives in the polymer film is preferably less than the content of the compound having a functional group.

[0101] The polymer film according to the present disclosure may also have a multilayer structure. The polymer film according to the present disclosure preferably has a layer A and a layer B on at least one surface of the layer A, and the layer B preferably contains a compound having the functional group. From the viewpoints of the dielectric loss tangent of the polymer film and adhesion to the metal layer, the polymer film according to the present disclosure preferably has a layer A containing a polymer or liquid crystal polymer having a dielectric loss tangent of 0.005 or less, and a layer B on at least one surface of the layer A containing a polymer or liquid crystal polymer having a dielectric loss tangent of 0.005 or less, and a compound having a functional group; and from the viewpoints of the dielectric loss tangent of the polymer film and adhesion to the metal layer, it is more preferable to have a layer A containing a polymer or liquid crystal polymer having a dielectric loss tangent of 0.005 or less, and a layer B on at least one surface of the layer A containing a polymer or liquid crystal polymer having a dielectric loss tangent of 0.005 or less, a compound having a functional group, and a third component. Layer A may contain only a polymer or liquid crystal polymer having a dielectric dissipation factor of 0.005 or less, or may contain a polymer or liquid crystal polymer having a dielectric dissipation factor of 0.005 or less and a compound having a functional group. Layer A may further contain a third component, but preferably does not contain one. Furthermore, the layer A preferably further contains a filler. Layer B preferably contains a polymer or liquid crystal polymer having a dielectric dissipation factor of 0.005 or less, and a compound having a functional group, and more preferably contains a polymer or liquid crystal polymer having a dielectric dissipation factor of 0.005 or less, a compound having a functional group, and a third component that fixes the compound having the functional group to the polymer having a dielectric dissipation factor of 0.005 or less. Furthermore, the content of the third component in Layer B is preferably greater than the content of the third component in Layer A, from the viewpoints of the dielectric loss tangent of the polymer film and the adhesion to the metal layer.

[0102] Furthermore, the polymer film according to the present disclosure preferably further includes a layer C in addition to the layer A and the layer B, and includes the layer B, the layer A, and the layer C in this order.

[0103] When a metal layer is present in addition to the above layers, Layer C is preferably a surface layer (outermost layer), and more preferably a surface layer on the side where the metal is attached. Furthermore, when the film according to the present disclosure is used as a laminate having a metal layer (for example, a metal foil or metal wiring), Layer C is preferably disposed between the metal layer and Layer A.

[0104] Layer C preferably contains a polymer or liquid crystal polymer having a dielectric dissipation factor of 0.005 or less, and a compound having a functional group; more preferably contains a polymer or liquid crystal polymer having a dielectric dissipation factor of 0.005 or less, a compound having a functional group, and a third component that fixes the compound having the functional group to the polymer or liquid crystal polymer having a dielectric dissipation factor of 0.005 or less. Furthermore, the content of the third component in Layer C is preferably greater than the content of the third component in Layer A, from the viewpoints of the dielectric loss tangent of the polymer film and the adhesion to the metal layer.

[0105] The average thickness of Layer A is not particularly limited, but from the viewpoint of the dielectric loss tangent of the polymer film and adhesion to the metal layer, it is preferably 5 μm to 90 μm, more preferably 10 μm to 70 μm, and particularly preferably 15 μm to 50 μm.

[0106] The method for measuring the average thickness of each layer in the polymer film according to the present disclosure is as follows. The polymer film is cut with a microtome, and the cross section is observed under an optical microscope to evaluate the thickness of each layer. Cross-sectional samples are cut out from three or more locations, and the thickness is measured at three or more points on each cross section, and the average of these measurements is taken as the average thickness.

[0107] The average thicknesses of Layer B and Layer C are preferably each independently smaller than the average thickness of Layer A, from the viewpoints of the dielectric loss tangent of the polymer film and the adhesion to the metal layer. Average thickness T of layer A A and the average thickness of layer B, T B T is the ratio of A / T BFrom the viewpoint of the dielectric loss tangent of the polymer film and the adhesion to the metal layer, the value of is preferably greater than 1, more preferably 2 to 100, even more preferably 2.5 to 20, and particularly preferably 3 to 10. Average thickness T of layer A A and the average thickness T of layer C C T is the ratio of A / T C From the viewpoint of the dielectric loss tangent of the polymer film and the adhesion to the metal layer, the value of is preferably greater than 1, more preferably 2 to 100, even more preferably 2.5 to 20, and particularly preferably 3 to 10. Also, the average thickness T of layer C C and the average thickness of layer B, T B T is the ratio of C / T B From the viewpoint of the linear expansion coefficient and adhesion to the metal layer, the value of is preferably 0.2 to 5, more preferably 0.5 to 2, and particularly preferably 0.8 to 1.2. Furthermore, the average thickness of Layer B and Layer C is preferably 0.1 μm to 20 μm, more preferably 0.5 μm to 15 μm, even more preferably 1 μm to 10 μm, and particularly preferably 3 μm to 8 μm, from the viewpoints of the dielectric loss tangent of the polymer film and the adhesion to the metal layer.

[0108] The average thickness of the polymer film according to the present disclosure is preferably 6 μm to 200 μm, more preferably 12 μm to 100 μm, and particularly preferably 20 μm to 60 μm, from the viewpoints of strength, dielectric tangent of the polymer film, and adhesion to the metal layer.

[0109] The average thickness of the polymer film is measured at any five points using an adhesive film thickness meter. For example, an electronic micrometer (product name "KG3001A" manufactured by Anritsu Corporation) is used as the film thickness meter, and the average thickness is calculated.

[0110] From the viewpoint of dielectric constant, the dielectric loss tangent of the polymer film according to the present disclosure is preferably 0.020 or less, more preferably 0.010 or less, even more preferably 0.005 or less, and particularly preferably greater than 0 and 0.003 or less. The dielectric loss tangent is measured in the same manner as the dielectric loss tangent described above.

[0111] The linear expansion coefficient of the polymer film according to the present disclosure is preferably from −20 ppm / K to 50 ppm / K, more preferably from −10 ppm / K to 40 ppm / K, even more preferably from 0 ppm / K to 35 ppm / K, and particularly preferably from 10 ppm / K to 30 ppm / K.

[0112] The linear expansion coefficient in the present disclosure is measured by the following method. Using a thermomechanical analyzer (TMA), a tensile load of 1 g is applied to both ends of a measurement sample of a polymer film or each layer, 5 mm wide and 20 mm long, and the sample is heated from 25°C to 200°C at a rate of 5°C / min. The sample is then cooled to 30°C at a rate of 20°C / min, and heated again at a rate of 5°C / min. The linear expansion coefficient is calculated from the slope of the TMA curve between 30°C and 150°C. When measuring each layer, a measurement sample may be prepared by scraping off the layer to be measured with a razor or the like. If it is difficult to measure the linear expansion coefficient by the above method, the following method shall be used. The film was cut with a microtome to prepare section samples, which were then placed under an optical microscope equipped with a heating stage system (HS82, Mettler-Toledo). The sample was then heated from 25 to 200°C at a rate of 5°C / min. The sample was then cooled to 30°C at a rate of 20°C / min, and heated again at a rate of 5°C / min. The thickness of the polymer film or each layer at 30°C (ts30) and at 150°C (ts150) were measured, and the dimensional change divided by the temperature change ((ts150-ts30) / (150-30)) was used as the linear expansion coefficient of the polymer film or each layer.

[0113] <Method of manufacturing polymer film> [Film forming] The method for producing the polymer film according to the present disclosure is not particularly limited, and known methods can be used. Suitable methods for producing the polymer film according to the present disclosure include, for example, a casting method, a coating method, an extrusion method, etc., with the casting method being particularly preferred. Furthermore, when the polymer film according to the present disclosure has a multilayer structure, suitable methods include, for example, a co-casting method, a multilayer coating method, a co-extrusion method, etc. Among these, the co-casting method is particularly preferred for producing a relatively thin film, and the co-extrusion method is particularly preferred for producing a thick film. When a multilayer structure in a polymer film is produced by the co-casting method or the multi-layer coating method, it is preferable to carry out the co-casting method or the multi-layer coating method using a composition for forming layer A, a composition for forming layer B, a composition for forming layer C, etc., in which the components of each layer, such as a liquid crystal polymer, are dissolved or dispersed in a solvent.

[0114] Examples of the solvent 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, and pentafluorophenol; ethers such as diethyl ether, tetrahydrofuran, and 1,4-dioxane; ketones such as acetone and cyclohexanone; esters such as ethyl acetate and γ-butyrolactone; and ethylene carbonate. nitriles such as acetonitrile and succinonitrile; amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone, and urea compounds such as tetramethylurea; nitro compounds such as nitromethane and nitrobenzene; sulfur compounds such as dimethyl sulfoxide and sulfolane; and phosphorus compounds such as hexamethylphosphoramide and tri-n-butylphosphate, and two or more of these may be used.

[0115] The solvent preferably contains an aprotic compound, particularly an aprotic compound without halogen atoms, because it is less corrosive and easier to handle. The proportion of the aprotic compound in the entire solvent is preferably 50% to 100% by mass, more preferably 70% to 100% by mass, and particularly preferably 90% to 100% by mass. Furthermore, the aprotic compound is preferably an amide such as N,N-dimethylformamide, N,N-dimethylacetamide, tetramethylurea, or N-methylpyrrolidone, or an ester such as γ-butyrolactone, because it easily dissolves the liquid crystal polymer, and more preferably N,N-dimethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone.

[0116] Furthermore, since the solvent easily dissolves the liquid crystal polymer, it preferably contains a compound having a dipole moment of 3 to 5. The proportion of the compound having a dipole moment of 3 to 5 in the entire solvent 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. As the aprotic compound, a compound having a dipole moment of 3 to 5 is preferably used.

[0117] Furthermore, the solvent preferably contains a compound having a boiling point of 220° C. or lower at 1 atmosphere, as this facilitates removal. The proportion of the compound having a boiling point of 220° C. or lower at 1 atmosphere in the entire solvent 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. As the aprotic compound, it is preferable to use a compound having a boiling point of 220° C. or lower at 1 atmospheric pressure.

[0118] In addition, in the method for producing a polymer film according to the present disclosure, a support may be used when the film is produced by the above-mentioned casting method, co-casting method, coating method, multilayer coating method, extrusion method, co-extrusion method, etc. In addition, when a metal layer (metal foil) or the like used in the laminate described below is used as a support, it may be used as is without peeling it off. Examples of the support include a metal drum, a metal band, a glass plate, a resin film, and a metal foil, and among these, the support is preferably a metal drum, a metal band, or a resin film. Examples of resin films include polyimide (PI) films. Examples of commercially available resin films include U-Pirex S and U-Pirex R manufactured by Ube Industries, Ltd., Kapton manufactured by DuPont-Toray Co., Ltd., and IF30, IF70, and LV300 manufactured by SKC Kolon PI. The support may have a surface treatment layer formed on its surface to facilitate peeling, which may be formed of hard chrome plating, fluororesin, or the like. The average thickness of the support is not particularly limited, but is preferably from 25 μm to 75 μm, and more preferably from 50 μm to 75 μm.

[0119] The method for removing at least a part of the solvent from the cast or coated film-like composition (cast film or coating film) is not particularly limited, and any known drying method can be used.

[0120] [Stretching] The polymer film according to the present disclosure can be appropriately combined with stretching in order to control molecular orientation and adjust the thermal expansion coefficient and mechanical properties. The stretching method is not particularly limited, and known methods can be used. The stretching may be performed in a solvent-containing state or in a dry film state. Stretching in a solvent-containing state may be performed by gripping the film and stretching, or by utilizing autogenous shrinkage due to drying without stretching. Stretching is particularly effective for improving breaking elongation and breaking strength when the film brittleness has decreased due to the addition of inorganic fillers, etc.

[0121] Furthermore, the method for producing a polymer film according to the present disclosure may include a step of polymerization using light or heat, if necessary. The light irradiation means and heat applying means are not particularly limited, and known light irradiation means such as a metal halide lamp and known heat applying means such as a heater can be used. The light irradiation conditions and heat application conditions are not particularly limited, and the irradiation can be carried out at a desired temperature and time in a known atmosphere.

[0122] [Heat treatment] The method for producing a polymer film according to the present disclosure preferably includes a step of heat treating (annealing) the film after it has been formed. Specifically, from the viewpoints of dielectric loss tangent and peel strength, the heat treatment temperature in the heat treatment step is preferably 260° C. to 370° C., more preferably 280° C. to 360° C., and even more preferably 300° C. to 350° C. The heat treatment time is preferably 15 minutes to 10 hours, and more preferably 30 minutes to 5 hours. Furthermore, the method for producing a polymer film according to the present disclosure may include other known steps as necessary.

[0123] <Application> The polymer film according to the present disclosure can be used in a variety of applications, and is particularly suitable for use as a film for electronic components such as printed wiring boards, and is more particularly suitable for use in flexible printed circuit boards. Furthermore, the polymer film according to the present disclosure can be suitably used as a polymer film for bonding metals.

[0124] (Laminate) The laminate according to the present disclosure may be any laminate in which the polymer film according to the present disclosure is laminated, but preferably has a polymer film according to the present disclosure and a metal layer disposed on the side of the polymer film where the concentration of the compound having the functional group is higher than in the interior, more preferably has a polymer film according to the present disclosure and a metal layer disposed on each of both sides of the polymer film, and particularly preferably has a metal layer disposed on each of both sides of the polymer film where the concentration of the compound having the functional group is higher than in the interior. The metal layer may be any known metal layer, but is preferably, for example, a copper layer. That is, the laminate according to the present disclosure preferably includes a polymer film according to the present disclosure and a metal layer in which the concentration of the compound having the functional group in the polymer film is higher than in the interior, and more preferably includes a polymer film according to the present disclosure and metal layers disposed on both sides of the polymer film. Furthermore, from the viewpoint of adhesion to the metal layer, it is preferable that the polymer film according to the present disclosure has a layer A and a layer B on at least one side of the layer A, the metal layer (preferably a copper layer) is disposed on the layer B, and the thickness of the layer B is greater than the thickness of the metal layer (preferably a copper layer) disposed on the layer B. The metal layer disposed on the surface on the layer B side is preferably a metal layer disposed on the surface of the layer B. Furthermore, the laminate according to the present disclosure preferably comprises a polymer film according to the present disclosure having Layer B, Layer A, and Layer C in this order, a metal layer disposed on the surface of the polymer film facing Layer B, and a metal layer disposed on the surface of the polymer film facing Layer C, and it is more preferable that both of the metal layers are copper layers. It is preferable that the metal layer arranged on the surface on the layer C side is a metal layer arranged on the surface of the layer C, and it is more preferable that the metal layer arranged on the surface on the layer B side is a metal layer arranged on the surface of the layer B, and that the metal layer arranged on the surface on the layer C side is a metal layer arranged on the surface of the layer C. The metal layer disposed on the surface on the layer B side and the metal layer disposed on the surface on the layer C side may be metal layers of the same material, thickness, and shape, or may be metal layers of different materials, thickness, and shape. From the viewpoint of adjusting the characteristic impedance, it is preferable that the metal layer disposed on the surface on the layer B side and the metal layer disposed on the surface on the layer C side be metal layers of different materials. Furthermore, from the viewpoint of adjusting the characteristic impedance, a metal layer may be laminated on the side of the metal layer arranged on the surface of one of the polymer films, layer B or layer C, where the concentration of the compound having the functional group is higher than in the interior, and another polymer film (preferably another liquid crystal polymer film) may be laminated on the other side.

[0125] The surface roughness Rz of the metal layer on the side in contact with the polymer film is preferably 1 μm to 10 μm, more preferably 1 μm to 5 μm, and particularly preferably 1.5 μm to 3 μm, when Layer C is not present; and from the viewpoint of reducing transmission loss of high-frequency signals, when Layer C is present, it is preferably less than 1 μm, more preferably 0.5 μm or less, and particularly preferably 0.3 μm or less. The surface roughness Rz of the metal layer is preferably as small as possible, and therefore the lower limit is not particularly limited, and is, for example, 0 μm.

[0126] In this disclosure, "surface roughness Rz" means the sum of the maximum peak height and the maximum valley depth observed on a roughness curve over a reference length, expressed in micrometers. In the present disclosure, the surface roughness Rz of a metal layer (for example, a copper layer) is measured by the following method. Using the non-contact surface / layer cross-sectional shape measurement system VertScan (manufactured by Ryoka Systems Co., Ltd.), an area 465.48 μm long and 620.64 μm wide is measured to create a roughness curve for the surface of the object (metal layer) and the average line of said roughness curve. A section corresponding to the reference length is extracted from the roughness curve. The surface roughness Rz of the object is measured by calculating the sum of the maximum peak height (i.e., the height from the average line to the peak) and the maximum valley depth (i.e., the height from the average line to the valley bottom) observed on the extracted roughness curve.

[0127] The method for attaching the polymer film according to the present disclosure to the metal layer is not particularly limited, and any known lamination method can be used.

[0128] The peel strength between the polymer film and the copper layer is preferably 0.5 kN / m or more, more preferably 0.7 kN / m or more, even more preferably 0.7 kN / m to 2.0 kN / m, and particularly preferably 0.9 kN / m to 1.5 kN / m.

[0129] In the present disclosure, the peel strength between a polymer film and a metal layer (for example, a copper layer) is measured by the following method. A 1.0 cm wide peel test piece is prepared from a laminate of a polymer film and a metal layer, and the polymer film is fixed to a flat plate with double-sided adhesive tape. The strength (kN / m) is measured when the metal layer is peeled from the polymer film at a rate of 50 mm / min using the 180° method in accordance with JIS C 5016 (1994).

[0130] The metal layer is 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 flex resistance.

[0131] The average thickness of the metal layer, preferably the copper layer, is not particularly limited, but is preferably 2 μm to 20 μm, more preferably 3 μm to 18 μm, and even more preferably 5 μm to 12 μm. The copper foil may be a carrier-attached copper foil formed on a support (carrier) in a peelable manner. Any known carrier can be used. The average thickness of the carrier is not particularly limited, but is preferably 10 μm to 100 μm, and more preferably 18 μm to 50 μm.

[0132] In order to further enhance the effects of the present disclosure, the metal layer preferably has a group capable of interacting with the polymer film on the surface thereof in contact with the polymer film, and the group capable of interacting with the polymer film preferably corresponds to a functional group of a compound having a functional group contained in the polymer film, such as an amino group and an epoxy group, or a hydroxyl group and an epoxy group. Examples of the group capable of interacting include the groups exemplified as functional groups in the compound having the functional group. Among these, from the viewpoints of adhesion and ease of processing, the interactive group is preferably a group capable of forming a covalent bond, more preferably an amino group or a hydroxy group, and particularly preferably an amino group.

[0133] The metal layer in the laminate according to the present disclosure may be a metal layer having a circuit pattern. It is also preferable to process the metal layer in the laminate according to the present disclosure into a desired circuit pattern by, for example, etching, to form a flexible printed circuit board. The etching method is not particularly limited, and known etching methods can be used. [Example]

[0134] The present disclosure will be described in more detail below with reference to examples. The materials, amounts used, ratios, processing details, processing procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present disclosure. Therefore, the scope of the present disclosure is not limited to the specific examples shown below.

[0135] <<Measurement method>> [Dielectric loss tangent] The dielectric loss tangent was measured at a frequency of 10 GHz using the resonance perturbation method. A 10 GHz cavity resonator (Kanto Electronics Application Development Co., Ltd., model CP531) was connected to a network analyzer (Agilent Technology, model E8363B). A sample of the polymer film or each layer (width: 2.0 mm x length: 80 mm) was inserted into the cavity resonator, and the dielectric loss tangent of the polymer film and each layer was measured from the change in resonance frequency before and after insertion for 96 hours in an environment of 25°C and 60% RH.

[0136] [Surface coverage] A polymer film not containing a compound having a functional group and a compound having a functional group were prepared. The surface energy was calculated for the polymer film not containing a compound having a functional group and the compound having a functional group. Similarly, the surface energy was calculated for the polymer film to be measured. Specifically, after conditioning at 25°C and a relative humidity of 60% for 24 hours, the contact angle with water and the contact angle with methylene iodide were measured, and the surface energy was calculated based on the measured contact angles using the Owens method. A calibration curve was prepared using the surface energy of a polymer film that does not contain a compound having a functional group and the surface energy of a compound having a functional group. From the created calibration curve, the surface coverage was calculated based on the surface energy of the polymer film to be measured.

[0137] [Peel strength] A 1.0 cm wide peel test piece was prepared from a laminate of a polymer film and a copper layer, and the polymer film was fixed to a flat plate with double-sided adhesive tape. The strength (kN / m) was measured when the polymer film was peeled from the copper layer of the laminate at a speed of 50 mm / min using the 180° method in accordance with JIS C 5016 (1994).

[0138] <<Production Example>> <Polymer with a dielectric loss tangent of 0.005 or less> LC-A: Liquid crystal polymer prepared according to the following manufacturing method

[0139] -Production of LC-A- A reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer, and a reflux condenser was charged with 940.9 g (5.0 mol) of 6-hydroxy-2-naphthoic acid, 377.9 g (2.5 mol) of 4-hydroxyacetaminophen, 415.3 g (2.5 mol) of isophthalic acid, and 867.8 g (8.4 mol) of acetic anhydride. The gas in the reactor was replaced with nitrogen gas, and the mixture was heated from room temperature (23°C) to 140°C over 60 minutes while stirring under a nitrogen gas stream, and then refluxed at 140°C for 3 hours. Next, while distilling off by-product acetic acid and unreacted acetic anhydride, the temperature was raised from 150°C to 300°C over 5 hours, and after holding at 300°C for 30 minutes, the contents were removed from the reactor and cooled to room temperature. The resulting solid was pulverized in a pulverizer to obtain a powdered liquid crystalline polyester (B1). The flow initiation temperature of this liquid crystalline polyester (B1) was 193.3°C.

[0140] The liquid crystal polyester (B1) obtained above was heated in a nitrogen atmosphere from room temperature to 160°C over 2 hours and 20 minutes, then heated from 160°C to 180°C over 3 hours and 20 minutes, and held at 180°C for 5 hours to undergo solid-state polymerization. The mixture was then cooled and pulverized in a pulverizer to obtain powdered liquid crystal polyester (B2). The flow initiation temperature of this liquid crystal polyester (B2) was 220°C.

[0141] The liquid crystalline polyester (B2) obtained above was heated in a nitrogen atmosphere from room temperature (23°C) to 180°C over 1 hour 25 minutes, then heated from 180°C to 255°C over 6 hours 40 minutes, and held at 255°C for 5 hours to undergo solid-state polymerization, followed by cooling to obtain powdered liquid crystalline polyester (LC-A). The flow initiation temperature of LC-A was 302°C. The melting point of this LC-A was measured using a differential scanning calorimeter and found to be 311°C.

[0142] LC-B: Liquid crystal polymer prepared according to the following manufacturing method

[0143] -Production of LC-B- A reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer, and a reflux condenser was charged with 940.9 g (5.0 mol) of 6-hydroxy-2-naphthoic acid, 377.9 g (2.5 mol) of 4-hydroxyacetaminophen, 415.3 g (2.5 mol) of isophthalic acid, and 867.8 g (8.4 mol) of acetic anhydride. The gas in the reactor was replaced with nitrogen gas, and the mixture was heated from room temperature (23°C) to 143°C over 60 minutes while stirring under a nitrogen gas stream, and then refluxed at 143°C for 1 hour. Next, while distilling off by-product acetic acid and unreacted acetic anhydride, the temperature was raised from 150°C to 300°C over 5 hours, and after holding at 300°C for 30 minutes, the contents were removed from the reactor and cooled to room temperature. The obtained solid was pulverized in a pulverizer to obtain a powdered liquid crystal polyester (B1).

[0144] The liquid crystal polyester (B1) obtained above was heated in a nitrogen atmosphere from room temperature to 160°C over 2 hours and 20 minutes, then heated from 160°C to 180°C over 3 hours and 20 minutes, and held at 180°C for 5 hours to undergo solid-state polymerization. The mixture was then cooled and pulverized in a pulverizer to obtain powdered liquid crystal polyester (B2).

[0145] The liquid crystal polyester (B2) obtained above was heated from room temperature (23°C) to 180°C over 1 hour and 20 minutes in a nitrogen atmosphere, then heated from 180°C to 240°C over 5 hours, and held at 240°C for 5 hours to undergo solid-state polymerization, followed by cooling to obtain powdered liquid crystal polyester (LC-B).

[0146] LC-C: Liquid crystal polymer prepared according to the following manufacturing method

[0147] -LC-C Manufacturing- A reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer, and a reflux condenser was charged with 941 g (5.0 mol) of 6-hydroxy-2-naphthoic acid, 273 g (2.5 mol) of 4-aminophenol, 415 g (2.5 mol) of isophthalic acid, and 1,123 g (11 mol) of acetic anhydride. The gas inside the reactor was replaced with nitrogen gas, and then the mixture was heated from room temperature (23°C) to 150°C over 15 minutes while stirring under a nitrogen gas stream, and refluxed at 150°C for 3 hours. Next, while distilling off by-product acetic acid and unreacted acetic anhydride, the temperature was raised from 150°C to 320°C over 3 hours, and maintained until an increase in viscosity was observed. The contents were then removed from the reactor and cooled to room temperature. The resulting solid was pulverized in a pulverizer to obtain a powdered liquid crystal polyester (C1).

[0148] The liquid crystal polyester (C1) obtained above was solid-phase polymerized by holding it at 250°C for 3 hours under a nitrogen atmosphere, then cooled and pulverized in a pulverizer to obtain a powdered liquid crystal polyester (LC-C).

[0149] <Polyphenylene ether> P-1: A mixture of commercially available polyphenylene ether pellets (SA120, manufactured by SABIC, weight-average molecular weight Mw 2,600) / bisphenol A epoxy resin (Epicron 850S, manufactured by DIC Corporation, average number of epoxy groups 2) / bisphenol A cyanate ester resin (Badcy, manufactured by Lonza Japan Co., Ltd.) / aromatic condensed phosphate ester (PX-200, manufactured by Daihachi Chemical Industry Co., Ltd.) / aluminum trisdiethylphosphinate (Exolit OP-935, manufactured by Clariant Japan Co., Ltd.) / zinc octanoate = 25 / 34 / 25 / 8 / 8 / 0.01 (mass ratio)

[0150] <Compounds with functional groups> Any of the following polymers A-1 to A-5 was used in the mass ratio shown in Table 1.

[0151] [Preparation of Polymer A-1] -Synthesis of Monomer 1- 5.0 g of 1,1-dimethoxycyclohexane, 9.0 g of 2-hydroxymethacrylate, 25.0 g of 1H,1H,2H,2H-perfluorooctanol, 0.87 g of pyridinium p-toluenesulfonate, and 30 mL of toluene were weighed into a 100 mL recovery flask and stirred at 40°C for 1 hour, followed by stirring at 40°C for 4 hours under a reduced pressure of 100 mmHg. The resulting reaction solution was cooled to room temperature (23°C) and then separated and washed with saturated aqueous sodium bicarbonate. The resulting organic layer was dried over anhydrous magnesium sulfate, concentrated, and subjected to silica gel column chromatography to obtain 8.0 g of Monomer 1 (represented by the following formula) as a colorless liquid (yield: 40%).

[0152] [ka]

[0153] -Synthesis of Monomer 2- A 2,000 mL three-neck flask equipped with a stirring blade, thermometer, and dropping funnel was charged with 100 g of 2-hydroxyethyl methacrylate and 240 mL of N,N-dimethylacetamide (DMAc) and cooled in an ice bath. Next, 126.8 g of 3-chloropropionyl chloride was added dropwise, and the mixture was stirred for 3 hours under ice cooling. After the resulting reaction solution was cooled to room temperature, 1,000 mL of ethyl acetate was separated and washed with 1 mol / L hydrochloric acid, saturated aqueous sodium bicarbonate, and water. The resulting organic layer was dried over anhydrous magnesium sulfate and concentrated to obtain 85 g of the target monomer 2 as a pale yellow liquid (88% yield).

[0154] [ka]

[0155] -Synthesis of Polymer A-1- 2.34 g of Monomer 1, 3.60 g of Cyclomer M100 (manufactured by Daicel Corporation), 4.05 g of Monomer 2, 18.57 g of methyl ethyl ketone (MEK), and 3.760 g of dimethyl 2,2'-azobis(isobutyrate) (polymerization initiator, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were weighed out and stirred at 70°C for 6 hours. After the reaction, the mixture was reprecipitated using 500 mL of methanol. The resulting solid was dissolved in 15 g of MEK, and 5.57 g of triethylamine and 0.01 g of p-methoxyphenol were added. The mixture was stirred at 60°C for 4 hours. The reaction mixture was returned to room temperature, reprecipitated using 500 mL of methanol, and dissolved in 25 g of MEK to obtain 5.1 g of polymer A-1 (yield 53%). In the following reaction formula, "M100" represents cyclomer M100. The content (content ratio) of each structural unit in the polymer is expressed in "mol %."

[0156] [ka]

[0157] [Preparation of Polymer A-2] -Synthesis of Monomer 3- Monomer 3 was synthesized using (3-mercaptopropyl)trimethoxysilane and 2-(perfluorohexyl)ethyl vinyl ether (CHEMINOX FAVE-6 (Unimatec)) according to the method described in Tetrahedron, 1991, 47, 4927-4940. In the following structural formula, Et represents an ethyl group.

[0158] [ka]

[0159] -Synthesis of Polymer A-2- 3.90 g of Monomer 3, 6.59 g of 3-glycidoxypropyltrimethoxysilane (FUJIFILM Wako Pure Chemical Industries, Ltd.), 6.93 g of 3-methacryloxypropyltrimethoxysilane (FUJIFILM Wako Pure Chemical Industries, Ltd.), 50 g of acetone, 1.38 g of 5% aqueous potassium carbonate solution, and 9.0 g of pure water were weighed and stirred at 50 °C for 5 hours. The resulting reaction solution was cooled to room temperature, and 50 g of methyl isobutyl ketone (MIBK) and 50 g of 5% saline solution were added to extract the organic layer. The organic layer was further washed once with 50 g of 5% saline solution and twice with 50 g of pure water, after which 10 g of magnesium sulfate and 0.01 g of p-methoxyphenol were added. After filtering off the magnesium sulfate, the solvent was evaporated under reduced pressure at 50 °C and 35 mmHg, yielding 20.2 g of Polymer A-2 as a 60.5 wt% MIBK solution (yield 95%). In the following structural formula, Me represents a methyl group and Et represents an ethyl group. The content (content ratio) of each structural unit in the polymer is expressed in "mol %."

[0160] [ka]

[0161] [Preparation of Polymer A-3] Polymer A-3 was produced in the same manner as Polymer A-1, except that the 25.0 g of 1H,1H,2H,2H-perfluorooctanol used in the synthesis of Monomer 1 was changed to 18.1 g of 1H,1H,2H,2H-perfluorohexanol.

[0162] [Preparation of Polymer A-4] Polymer A-4 was produced in the same manner as Polymer A-2, except that the 2-(perfluorohexyl)ethyl vinyl ether (CHEMINOX FAVE-6 (Unimatec)) used in the synthesis of Monomer 3 was replaced with 2-(perfluorobutyl)ethyl vinyl ether (CHEMINOX FAVE-4 (Unimatec)).

[0163] [Preparation of Polymer A-5] -Synthesis of Polymer A-5- 2.34 g of Monomer 1, 3.60 g of Cyclomer M100 (manufactured by Daicel Corporation), 4.05 g of Monomer 2, 18.57 g of methyl ethyl ketone (MEK), and 3.760 g of dimethyl 2,2'-azobis(isobutyrate) (polymerization initiator, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were mixed and stirred at 70°C for 6 hours. After the reaction, the mixture was reprecipitated using 500 mL of methanol. The resulting solid was dissolved in 15 g of MEK, and 5.57 g of triethylamine and 0.01 g of p-methoxyphenol were added. The mixture was then heated to 60°C, and a separately prepared solution consisting of 6.12 g of tetraethylene glycol bis(3-mercaptopropionate) (EGMP-4, manufactured by SC Organic Chemical Co., Ltd.) and 6.12 g of MEK was added over 2 hours. The mixture was further stirred at 60°C for 4 hours, and the reaction solution was returned to room temperature, after which it was reprecipitated using 500 mL of methanol. The resulting solid was dissolved in 25 g of MEK to obtain Polymer A-5.

[0164] The difference in SP value between LC-A, LC-B or LC-C and Polymer A-1, Polymer A-2, Polymer A-3, Polymer A-4 or Polymer A-5 (compound having a functional group) is 5 MPa.0.5 It was as follows.

[0165] <Third component> C-1: The following mixture was used as the third component C-1 and was added in the mass ratio shown in Table 1. Tricyclodecane dimethanol diacrylate (A-DCP, manufactured by Shin-Nakamura Chemical Co., Ltd.; multifunctional monomer): 46 parts by mass IRGACURE 290 (BASF): 3 parts by weight

[0166] The difference in SP value between C-1 and the above LC-A, LC-B or LC-C is 5 MPa. 0.5 It was as follows.

[0167] [Filler] F-1: Liquid crystal polymer particles prepared according to the following manufacturing method

[0168] -LCD manufacturing- A reactor equipped with a stirrer, torque meter, nitrogen gas inlet tube, thermometer, and reflux condenser was charged with 1,034.99 g (5.5 mol) of 2-hydroxy-6-naphthoic acid, 378.33 g (1.75 mol) of 2,6-naphthalenedicarboxylic acid, 83.07 g (0.5 mol) of terephthalic acid, 272.52 g of hydroquinone (2.475 mol, 0.225 molar excess relative to the combined molar amount of 2,6-naphthalenedicarboxylic acid and terephthalic acid), 1,226.87 g (12 mol) of acetic anhydride, and 0.17 g of 1-methylimidazole as a catalyst. After the gas in the reactor was replaced with nitrogen gas, the mixture was heated from room temperature to 145°C over 15 minutes under nitrogen gas flow with stirring and refluxed at 145°C for 1 hour.

[0169] Next, while distilling off the by-product acetic acid and unreacted acetic anhydride, the temperature was raised from 145°C to 310°C over 3 hours and 30 minutes, and after maintaining at 310°C for 3 hours, the solid liquid crystalline polyester (LC-D) was taken out and cooled to room temperature. The flow initiation temperature of this polyester (LC-D) was 265°C.

[0170] -Production of Liquid Crystal Polymer Particles (F-1)- The liquid crystalline polyester (LC-D) was pulverized using a jet mill (Kurimoto Tekko KJ-200) to obtain liquid crystalline polyester fine particles (liquid crystalline polymer particles (F-1)). The average particle size of the liquid crystalline polyester fine particles was 9 μm.

[0171] F-2: Commercially available silica fine particles (SO-C2, manufactured by Admatechs Co., Ltd.) having an average particle size of 0.5 μm were used so that the solid content was the amount shown in Table 1. F-3: Tetrafluoroethylene and perfluoroalkoxyethylene copolymer (PFA) particles, melting point 280°C, average particle size 0.2 μm to 0.5 μm, dielectric loss tangent 0.001 F-4: Commercially available hollow powder with an average particle size of 16 μm (Glass Bubbles iM30K, manufactured by 3M Japan Ltd.) F-5: Boron nitride particles, melting point >500°C, HP40MF100 (manufactured by Mizushima Ferroalloy Co., Ltd.), dielectric dissipation factor 0.0007

[0172] (Examples 1 to 20 and Comparative Example 1) <Film forming> The methods described in Table 1 were selected from the following multilayer coating A and multilayer coating B, single layer coating, and co-casting.

[0173] [Multilayer Coating A] -Preparation of polymer solution- A polymer having a dielectric dissipation factor of 0.005 or less was added to N-methylpyrrolidone and dissolved by stirring at 140°C for 4 hours under a nitrogen atmosphere. Subsequently, a compound having a functional group and a third component were added as needed to achieve the mass ratios shown in Table 1, and the mixture was stirred at 25°C for 30 minutes to obtain each polymer solution. The solids concentration of the polymer solution for Layer A (core layer) was 10% by mass, and that for Layer B (surface layer) was 5% by mass. Subsequently, the polymer solution for layer A and the polymer solution for layer B were obtained by first passing the polymer solution through a sintered fiber metal filter having a nominal pore size of 5 μm, and then passing the polymer solution through a sintered fiber metal filter also having a nominal pore size of 5 μm. When the additive was not soluble in N-methylpyrrolidone, a liquid crystal polymer solution was prepared without adding the additive, and after passing it through the sintered fiber metal filter, the additive was added and stirred.

[0174] -Film production- The obtained polymer solution for Layer A (core layer) and the polymer solution for Layer B (surface layer) were transferred to a slot die coater equipped with a slide coater and applied to the treated surface of a copper foil (Fukuda Metal Foil & Powder Co., Ltd., CF-T9DA-SV-18, thickness 18 μm) to form a three-layer film (surface layer / core layer / surface layer). The solvent was removed from the coating by drying at 40°C for 4 hours, yielding a polymer film.

[0175] [Multilayer coating B] -Preparation of polymer solution- The polymer and the additives shown in Table 1 were added to toluene to a solid concentration of 80%, and the mixture was stirred for 60 minutes to obtain polymer solutions for Layer A and Layer B, respectively.

[0176] -Film production- The polymer solutions for Layer A and Layer B were applied in a multilayer manner to the treated surface of a copper foil (manufactured by Fukuda Metal Foil & Powder Co., Ltd., CF-T9DA-SV-18, thickness 18 μm, surface roughness Rz 0.85 μm on the treated surface) using a slot die coater equipped with a slide coater. The coating was dried at 100°C for 3 minutes and then at 170°C for 3 minutes to remove the solvent from the coating. The temperature was then increased from room temperature to 200°C at a rate of 1°C / min and maintained at that temperature for 2 hours for heat treatment, yielding a polymer film (laminate) with a copper layer.

[0177] [Single layer coating] -Preparation of polymer solution- A polymer having a dielectric dissipation factor of 0.005 or less was added to N-methylpyrrolidone and dissolved by stirring at 140°C for 4 hours under a nitrogen atmosphere. Then, a compound having a functional group and a third component were added in the mass ratios shown in Table 1, and the mixture was stirred at 25°C for 30 minutes to obtain a polymer solution. The solid content was 10% by mass. When the additive was not soluble in N-methylpyrrolidone, a liquid crystal polymer solution was prepared without adding the additive, and after passing it through the sintered fiber metal filter, the additive was added and stirred. Subsequently, the mixture was first passed through a sintered fiber metal filter having a nominal pore size of 5 μm, and then passed through another sintered fiber metal filter also having a nominal pore size of 5 μm to obtain a polymer solution.

[0178] -Film production- The obtained polymer solution was transferred to a slot die coater and applied to the treated surface of a copper foil (CF-T9DA-SV-18, thickness 18 μm, manufactured by Fukuda Metal Foil & Powder Co., Ltd.) The solvent was removed from the coating by drying at 40° C. for 4 hours, yielding a polymer film.

[0179] [Co-casting] -Preparation of polymer solution- The polymer shown in Table 1 was added to N-methylpyrrolidone and stirred at 140°C for 4 hours under a nitrogen atmosphere to form a solution, which was then passed through a sintered fiber metal filter with a nominal pore size of 10 μm, followed by another sintered fiber metal filter with a nominal pore size of 10 μm. Next, the additives shown in Table 1 were added in the mass ratios shown in Table 1, and the mixture was stirred at 25°C for 30 minutes to obtain a polymer solution. When the additive was not soluble in N-methylpyrrolidone, a liquid crystal polymer solution was prepared without adding the additive, and after passing it through the sintered fiber metal filter, the additive was added and stirred.

[0180] -Film production- The obtained polymer solution for Layer A and the polymer solution for Layer B were sent to a casting die equipped with a multi-manifold adjusted for co-casting a three-layer structure (Layer B / Layer A / Layer B), and cast onto the treated surface of a copper foil (manufactured by Fukuda Metal Foil & Powder Co., Ltd., CF-T9DA-SV-18, thickness 18 μm, surface roughness of the attached surface (treated surface) Rz 0.85 μm). The cast film was dried at 60°C for 4 hours to remove the solvent, and a polymer film was obtained.

[0181] <Polymerization reaction> For polymer films containing C-1 as the third component, after the drying process, an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) was used to irradiate the film with an irradiation dose of 300 mJ / cm. 2 The multifunctional monomer (multifunctional reactive compound) in C-1 was polymerized by ultraviolet light irradiation, forming a three-dimensional crosslinked structure. Therefore, the polymer film contains a cured product of the multifunctional monomer.

[0182] <Preparation of copper clad laminate> [Metal layer formation process] - Copper clad laminate precursor process - Copper foil (Fukuda Metal Foil & Powder Co., Ltd., CF-T9DA-SV-18, thickness 18 μm) was placed on the polymer film and laminated for 1 minute using a laminator (Nikko Materials Co., Ltd., Vacuum Laminator V-130) at 140°C and a lamination pressure of 0.4 MPa to obtain a copper-clad laminate precursor.

[0183] -Main thermocompression bonding process- The obtained copper-clad laminate precursor was subjected to thermocompression bonding for 10 minutes at 300°C and 4.5 MPa using a thermocompression bonding machine ("MP-SNL" manufactured by Toyo Seiki Seisakusho, Ltd.), to produce a copper-clad laminate (laminate).

[0184] -Annealing process- The obtained copper-clad laminate was further heated from room temperature (25°C) to 280°C at a rate of 1°C / min in a nitrogen atmosphere, and then subjected to heat treatment by holding at 280°C for 2 hours to obtain a copper-clad laminate (laminate).

[0185] <<Evaluation>> The prepared polymer films were evaluated by the methods described above, and the results are shown in Table 1.

[0186] [Table 1]

[0187] The polymer films of Examples 1 to 20 were polymer films in which the concentration of the compound having a functional group was higher on both surfaces than in the interior. It was also confirmed that the surface coverage of the compound having a functional group on both surfaces of the polymer film of Example 2 was 100% by area. On the other hand, the polymer film of Comparative Example 1 did not contain a compound having a functional group, and there was no difference in concentration between the surface and the interior. In addition, in the polymer films of Examples 1 and 3, the surface coverage of the compound having a functional group on both surfaces was 50 area % or more. On the other hand, in the polymer film of Comparative Example 1, the surface coverage of the compound having a functional group was 0 area % on both surfaces.

[0188] The results shown in Table 1 show that the polymer films of Examples 1 to 20 according to the present disclosure are superior to the polymer film of Comparative Example 1 in adhesion to the substrate. On the other hand, the polymer film of Comparative Example 1, which did not contain a compound having a functional group, had insufficient peel strength and was poor in adhesion to the substrate. Furthermore, from the results shown in Table 1, the polymer films of Examples 1 to 19 according to the present disclosure are polymer films with low dielectric loss tangents.

Claims

1. A polymer having a dielectric loss tangent of 0.005 or less, and a compound having a functional group, the concentration of the compound having the functional group on at least one surface is higher than that in the interior; the functional group is a covalently bondable group, the covalently bondable group is at least one group selected from the group consisting of an epoxy group, an oxetanyl group, and a halogenated alkyl group; the compound having a functional group contains a silicon atom or a fluorine atom, When the thickness of the polymer film is 30 μm or less, the surface refers to a region from the outermost surface of the polymer film to a position corresponding to 10% of the thickness of the polymer film, and when the thickness of the polymer film is more than 30 μm, the surface refers to a region from the outermost surface of the polymer film to a position 3 μm away in the thickness direction. The interior refers to a region from the center of the polymer film in the thickness direction to a position corresponding to a thickness of ±5% of the thickness of the polymer film when the thickness of the polymer film is 30 μm or less, and refers to a region from the center of the polymer film in the thickness direction to a position away from the center of the polymer film in the thickness direction by ±1.5 μm. Polymer film.

2. A polymer having a dielectric loss tangent of 0.005 or less, and a compound having a functional group, a surface coverage of the compound having a functional group on at least one surface of the polymer film is 50 area % or more; the functional group is a covalently bondable group, the covalently bondable group is at least one group selected from the group consisting of an epoxy group, an oxetanyl group, and a halogenated alkyl group; The compound having a functional group contains a silicon atom or a fluorine atom. Polymer film.

3. 3. The polymer film according to claim 1, further comprising a third component that fixes the compound having the functional group to the polymer having a dielectric loss tangent of 0.005 or less.

4. The polymer film according to claim 3 , wherein the third component comprises a cured product of a multifunctional reactive compound.

5. The polymer film according to claim 3 or 4, wherein the third component comprises a polymer having a functional group that interacts with the compound having the functional group and that is compatible with the polymer having a dielectric loss tangent of 0.005 or less.

6. The difference between the SP value of the polymer having a dielectric loss tangent of 0.005 or less by the Hoy method and the SP value of the compound having a functional group by the Hoy method is 5 MPa. ０．５ The polymer film according to any one of claims 1 to 5, wherein:

7. The polymer film according to any one of claims 1 to 6, comprising a layer A and a layer B on at least one surface of the layer A, and the layer B contains the compound having the functional group.

8. 8. The polymer film according to claim 7, wherein Layer B comprises a third component that fixes the compound having the functional group to the polymer having a dielectric loss tangent of 0.005 or less.

9. The polymer film according to claim 8 , wherein the content of the third component in the layer B is greater than the content of the third component in the layer A.

10. Further comprising a layer C, The polymer film according to any one of claims 7 to 9, comprising the Layer B, the Layer A, and the Layer C in this order.

11. The polymer film according to any one of claims 1 to 10, wherein the polymer film has a linear expansion coefficient of -20 ppm / K to 50 ppm / K.

12. The polymer film according to any one of claims 1 to 11, wherein the polymer film has a dielectric loss tangent of 0.01 or less.

13. The polymer film according to any one of claims 1 to 12, which contains a filler.

14. 14. The polymer film of claim 13, wherein the number density of the fillers is greater inside the polymer film than on the surface thereof.

15. The polymer film according to any one of claims 1 to 14, wherein the polymer having a dielectric loss tangent of 0.005 or less comprises a liquid crystal polymer.

16. 16. The polymer film according to claim 15, wherein the polymer having a dielectric loss tangent of 0.005 or less comprises a liquid crystal polymer having a constitutional unit represented by any one of formulas (1) to (3). 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, a naphthylene group, or a biphenylylene group; Ar ２ and Ar ３ each independently represents a phenylene group, a naphthylene group, a biphenylylene group, or a group represented by the following formula (4), X and Y each independently represent an oxygen atom or an imino group, Ar １ ~Ar ３ Each hydrogen atom in may be independently substituted with a halogen atom, an alkyl group, or an aryl group. Formula (4) -Ar ４ -Z-Ar ５ -[[]]END]] In formula (4), Ar ４ and Ar ５ each independently represents 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.

17. Liquid crystal polymers, and a compound having a functional group, the concentration of the compound having the functional group on at least one surface is higher than that in the interior; the functional group is a covalently bondable group, the covalently bondable group is at least one group selected from the group consisting of an epoxy group, an oxetanyl group, and a halogenated alkyl group; The compound having the functional group contains a silicon atom or a fluorine atom. When the thickness of the polymer film is 30 μm or less, the surface refers to a region from the outermost surface of the polymer film to a position corresponding to 10% of the thickness of the polymer film, and when the thickness of the polymer film is more than 30 μm, the surface refers to a region from the outermost surface of the polymer film to a position 3 μm away in the thickness direction. The interior refers to a region from the center of the polymer film in the thickness direction to a position corresponding to a thickness of ±5% of the thickness of the polymer film when the thickness of the polymer film is 30 μm or less, and refers to a region from the center of the polymer film in the thickness direction to a position away from the center of the polymer film in the thickness direction by ±1.5 μm. Polymer film.

18. Liquid crystal polymers, and a compound having a functional group, a surface coverage of the compound having a functional group on at least one surface of the polymer film is 50 area % or more; the functional group is a covalently bondable group, the covalently bondable group is at least one group selected from the group consisting of an epoxy group, an oxetanyl group, and a halogenated alkyl group; The compound having a functional group contains a silicon atom or a fluorine atom. Polymer film.

19. A laminate comprising the polymer film according to any one of claims 1 to 18 and a metal layer disposed on a surface of the polymer film where the concentration of the compound having the functional group is higher than in the interior.

20. 20. The laminate of claim 19, further comprising a metal layer disposed on each side of the polymer film.

21. the metal layer is a copper layer, 21. The laminate according to claim 19 or 20, wherein the peel strength between the polymer film and the copper layer is 0.5 kN / m or more.

22. the polymer film has a layer A and a layer B on at least one surface of the layer A, the layer B containing the compound having the functional group; The laminate according to any one of claims 19 to 21, wherein the metal layer is disposed on the layer B.

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