TWI764429B - Liquid composition, liquid crystal polyester film, and method for producing the liquid crystal polyester film, laminated film, and method for producing the same - Google Patents

Abstract

The present invention provides a liquid composition for producing a liquid crystal polyester film, a liquid crystal polyester film obtained from the liquid composition, and a method for producing the liquid crystal polyester film, and further provides a laminate having the liquid crystal polyester film A film and a method for producing the laminated film. The liquid composition 1 of the present invention is a liquid composition obtained by dissolving a liquid crystal polyester in a solvent by dispersing a liquid crystal polyester powder of the same or the same type as the liquid crystal polyester to increase the solid content concentration.

Description

Liquid composition, liquid crystal polyester film, and production method of the liquid crystal polyester film, laminated film, and production method of the laminated film

The present invention relates to a liquid composition for producing a liquid crystal polyester film, a liquid crystal polyester film obtained from the liquid composition, and a method for producing the liquid crystal polyester film, and further relates to a laminate film having the liquid crystal polyester film And the manufacturing method of this laminated film.

Liquid crystal polyester film has excellent low moisture absorption, high frequency characteristics, flexibility, high gas barrier properties, thin-wall formability, etc., so it is suitable for electronic products such as flexible printed wiring boards, rigid printed wiring boards, and module substrates. In recent years, the demand for insulating films or surface protection films for substrates has been increasing.

In addition, there are various proposals for the manufacturing method (film-forming method) of the above-mentioned liquid crystal polyester film, and Patent Document 1 discloses an example of a solution-type coating film-forming (so-called casting method). In addition, as a method other than the above-mentioned solution-type coating and film formation, the resinized pellets are extruded into a film shape by a T-die casting method in a state heated to a melting point temperature or higher, or are formed into a film shape by thermal fusion. The inflation method is performed by molding into a film shape (Patent Document 2).

prior art literature

[Patent Document 1] Japanese Patent Application Laid-Open No. 2011-167847

[Patent Document 2] Japanese Patent Application Laid-Open No. 2013-193438

However, for example, as a wiring board on which electronic components are mounted, the liquid crystal polyester is formed into a film on a metal foil as an insulating film, the liquid crystal polyester film is used as a metal-clad laminate, or sputtering or plating is performed. When used as a laminate, in this case, the above-mentioned conventional method for producing the liquid crystal polyester film has problems in productivity and film formation.

For example, the current solution-type coating and film formation (casting method) of a monomer or oligomer of a liquid crystal polyester is excellent in quality such as orientation and thickness, but requires time for thermal drying and firing, and has a problem of low productivity.

On the other hand, film formation of the resinized (polymerized) liquid crystal polyester by the thermal melt inflation method or the T-die casting method has difficulty in reproducibility of orientation, thickness, and the like.

Liquid crystal polyesters have properties called "liquid crystals" that are crystalline in a molten state (liquid state), and have properties of transient orientation from the glass transition Tg state (amorphous state). When a film is formed by the melt inflation method or the T-die casting method, a molecular orientation is generated in the flow direction (MD: Machine Direction) of the molten resin and has anisotropy. A liquid crystal polyester film that is fragile in the TD (Transverse Direction) direction of the cross direction, and a metal-clad laminate formed by laminating the liquid crystal polyester film as an insulating film and a metal foil, if stretched in the TD direction, Then, there is a problem that cracks are easily caused in the MD direction.

In particular, when the metal foil is etched to form a conductor pattern whose longitudinal direction is the MD direction, there is a problem that the insulating film (liquid crystal polyester film) between the conductor patterns is easily broken along the conductor pattern.

In addition, the anisotropy possessed by the liquid crystal polyester film causes warping and deformation of the metal-clad laminate obtained by laminating such a liquid crystal polyester film as an insulating film.

Therefore, when the insulating film of the metal-clad laminate is formed of a liquid crystal polymer, it is desirable not to have orientation in any of the MD and TD directions, and it is more preferable that the MD, TD, and Z (thickness) directions have orientation. There is no orientation in any direction. In addition, as a modification method for liquid crystal polyester to cope with the orientation and linear expansion, the addition of fillers such as nano-sized silica has been attempted. However, when the liquid crystal polyester film is applied as a circuit pattern layer ( The inorganic filler segregates on the surface of the liquid crystal polyester film during sputtering, plating, etc. of silver, copper, etc. of the metal layer) to easily cause pinholes and also cause dielectric loss.

In addition, as described in Patent Document 1, a method of producing a liquid crystal polyester film by a casting method using a liquid composition containing a solvent and a liquid crystal polyester (a precursor of liquid crystal polyester) dissolved in the solvent is proposed, although this The method solves the orientation (MD, TD, Z), but has the problem of drying of the solvent during casting, and the problem of requiring load (time) for firing, and the problem of foaming in the film during film forming.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a liquid crystal polyester film which is used in the production of liquid crystal polyester films in order to increase the efficiency of drying time and firing time and to suppress foaming of the film during molding. A technique for film-forming by dispersing a liquid crystal polyester filler (liquid crystal polyester powder) in a liquid composition.

Hereinafter, the means for solving the problem will be described together with the reference numerals used in the form for carrying out the invention. The reference numerals are used to clearly describe the correspondence between the description of the scope of the invention and the description of the mode for carrying out the invention, and are of course not intended to limit the interpretation of the technical scope of the present invention.

In order to achieve the above-mentioned object, the liquid composition 1 of the present invention, in a solution containing a solvent and a liquid crystal polyester dissolved in the solvent, contains the same or homologous liquid crystal polyester with respect to the liquid crystal polyester dissolved in the solvent. 100 parts by weight of the liquid crystal polyester is 10 to 1000 parts by weight, preferably 10 to 800 parts by weight, and more preferably 60 to 300 parts by weight of the liquid crystal polyester powder from the viewpoint of preventing shrinkage, which increases the solid content concentration.

The liquid crystal polyester film 10 of the present invention is non-oriented, and is formed using the liquid composition 1 described above.

The manufacturing method of the liquid crystal polyester film of the present invention includes a process of casting the liquid composition 1 on a substrate, and a process of removing the solvent from the liquid composition on the substrate.

In addition, the laminated film 20 of the present invention includes a liquid crystal polyester film layer 21 formed using the liquid composition 1, and a metal layer 26 laminated on the surface of the liquid crystal polyester film layer 21. The liquid crystal polyester film may be laminated on both sides of the filler addition layer 23 formed of liquid crystal polyester to which a filler such as silica, talc, silicon nitride nitride, aluminum nitride, or fluorine-based powder is preferably added. The structure (laminated structure) of the liquid crystal polyester layers 22 and 24 formed of the liquid crystal polyester with no filler added.

The manufacturing method of the laminated film 20 of the present invention is characterized by comprising:

A metal layer is formed on the surface of the substrate (eg, OPP film (stretched polypropylene), CPP film (non-stretched polypropylene), HPPE film (high-pressure polyethylene)) 40 by vapor deposition or sputtering 26. After the liquid composition 1 is cast on the metal layer 26 and dried, the substrate 40 is peeled off to manufacture the laminate film precursor 30 having the metal layer 26 and the liquid crystal polyester film precursor 31; and

Taking the laminated film precursor 30 as an example, in the firing furnace 51, the laminated film precursor 30 is made to be perpendicular to the laminated film in a state where the tension acting on the laminated film precursor 30 is released. The film precursor 30 is moved up and down (curved) in the direction of the horizontal plane (conveying direction) and heat-treated to remove the residual solvent contained in the liquid crystal polyester film precursor 31 to produce the metal layer 26 and the liquid crystal polyester. The manufacturing process of the laminated film 20 of the film layer 21 .

It should be noted that, in the firing furnace 51, gas nozzles (not shown in the figure) are alternately arranged above and below with respect to the advancing direction of the laminated film precursor 30 across the continuously conveyed laminated film precursor 30. shown), gas (inactive gas) can be blown to the laminated film precursor 30 from the gas nozzle, so that the laminated film precursor 30 can move up and down in the direction perpendicular to the horizontal plane of the laminated film precursor 30 (bending).

In addition, a conductor pattern may be formed on the metal layer 26 of the laminated film 20 as a printed wiring board.

The following remarkable effects can be obtained by the configuration of the present invention described above.

First, the liquid composition 1 of the present invention is improved by dispersing powder (liquid crystal polyester powder) of the same or homologous liquid crystal polyester as the liquid crystal polyester in a solution containing a solvent and a liquid crystal polyester dissolved in the solvent. The composition with the solid content concentration can reduce the amount of the solvent, thereby reducing the drying time and the firing time when a liquid crystal polyester film is produced by the casting method using the liquid composition 1 of the present invention, and can further suppress the film forming. generated foam.

It is presumed that this is due to the mutual benefit of the phases at the time of film formation and at the time of firing. That is to say, when the liquid crystal polyester film is produced, the liquid crystal polyester dissolved in a solvent (hereinafter, the liquid crystal polyester dissolved in a solvent is also referred to as a "liquid crystal polyester precursor" in the specification) is compared with the same or homologous liquid crystal The polyester powder does not show thixotropy, etc., and can be uniformly coated with a comma coater or the like. In addition, it is estimated that the residual solvent in the liquid composition 1 is in the range of about 4 to 30% during the initial drying process after the coating. ), the liquid crystal polyester precursor functions as a splicing agent for the liquid crystal polyester powder, thereby completing film formation, and further, in the firing process performed after the drying process, the liquid crystal polyester powder is melted At the same time, the liquid crystal polyester precursor undergoes a condensation reaction (polymerization), and finally the liquid crystal polyester powder and the liquid crystal polyester precursor co-crystallize to form a liquid crystal polyester film. In conclusion, the drying time and the sintering time are greatly reduced, and a non-foaming liquid crystal polyester film is obtained.

In addition, the liquid crystal polyester film 10 obtained from the liquid composition 1 of the present invention may be non-oriented and not have the anisotropy of ordinary liquid crystal polyester films, and can improve mechanical strength such as tensile force with respect to the width direction. .

In addition, in the manufacturing method of the laminated film 20 of the present invention, as described above, the sputtering or vapor deposition of the metal layer 26 is not performed after the firing of the liquid crystal polyester film, but is performed on the liquid crystal polyester It is implemented before the firing of the film.

Thereby, first, the problem of pinholes generated by sputtering and vapor deposition of the metal layer 26 can be solved. That is, there is a remarkable effect of closing the pinholes due to the following of the metal layer 26 when the liquid crystal polyester film is condensed at the time of firing.

Furthermore, when the liquid crystal polyester film is fired, high bonding with the sputtering interface of the metal layer 26 is obtained together with thermal activity, so that, for example, when the laminated film 20 of the present invention is used as a flexible substrate (printing In the case of a wiring board), the metal layer 26 can withstand micro-etching in the subsequent process.

Hereinafter, the liquid composition 1 of the present invention, the liquid crystal polyester film 10 produced from the liquid composition 1, and the production method of the liquid crystal polyester film 10 will be described with reference to the drawings, and further, the liquid crystal The laminated film 20 in which the liquid crystal polyester film layer 21 of the polyester film 10 is laminated with the metal layer 26 and the manufacturing method of the laminated film 20 will be described.

[Liquid composition]

The liquid composition 1 of the present invention is obtained by dissolving liquid crystal polyester in a solvent by immersing a liquid crystal polyester powder (hereinafter, also referred to as LCP powder in the specification) of the same or homologous liquid crystal polyester as the liquid crystal polyester to increase the solid content. concentration of the composition. Hereinafter, the liquid crystal polyester, the solvent, and the liquid crystal polyester powder will be described.

[Liquid crystal polyester]

The liquid crystalline polyester used in the present invention is a polyester having so-called optical anisotropy at the time of melting and the property of forming an anisotropic melt at a temperature of 450° C. or lower.

As the liquid crystal polyester, preferable liquid crystal polyester has a structural unit represented by the following formula 1 (hereinafter referred to as "formula 1 structural unit") and a structural unit represented by the following formula 2 (hereinafter referred to as "formula 2 structure"). unit”) and the structural unit represented by the following formula 3 (hereinafter referred to as “structural unit of formula 3”), and the content of the structural unit represented by formula 1 is 30 to 80 mol relative to the total content of all structural units %, the content of the structural unit represented by formula 2 is 10 to 35 mol %, and the content of the structural unit represented by formula 3 is 10 to 35 mol %.

-O-Ar ¹ -CO- (Formula 1)

-CO-Ar ² -CO- (Formula 2)

-X-Ar ³ -Y- (Formula 3)

(In formulas 1 to 3, Ar ¹ represents a phenylene group or a naphthylene group, Ar ² represents a phenylene group, a naphthylene group or a group represented by the following formula 4, and Ar ³ represents a phenylene group or the following formula In the group represented by 4, X and Y are independently represented by O or NH. It should be noted that the hydrogen atoms bonded to the aromatic rings of Ar ¹ , Ar ² and Ar ³ may be replaced by halogen atoms, alkyl groups or aryl groups replace.)

-Ar ¹¹ -Z-Ar ¹² - (Formula 4)

(In the formula, Ar ¹¹ and Ar ¹² are each independently and represent a phenylene group or a naphthylene group, and Z represents O, CO or SO ₂ .)

The structural unit of formula 1 is a structural unit derived from an aromatic hydroxycarboxylic acid, and examples of the aromatic hydroxycarboxylic acid include p-hydroxybenzoic acid, m-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 3-hydroxyl -2-naphthoic acid, 4-hydroxy-1-naphthoic acid, etc.

The structural unit of formula 2 is a structural unit derived from an aromatic dicarboxylic acid, and examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5- Naphthalenedicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-dicarboxybiphenyl, 4,4'-dicarboxybenzophenone, etc.

The structural unit of formula 3 is a structural unit derived from an aromatic diol, an aromatic amine having a phenolic hydroxyl group, or an aromatic diamine. Examples of the aromatic diol include hydroquinone, resorcinol, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, bis(4- hydroxyphenyl) ether, bis-(4-hydroxyphenyl) ketone, bis-(4-hydroxyphenyl) sulfone, etc.

In addition, as the aromatic amine having the phenolic hydroxyl group, 4-aminophenol (p-aminophenol), 3-aminophenol (m-aminophenol), etc. can be mentioned, and as the aromatic diamine , 1,4-phenylenediamine, 1,3-phenylenediamine, etc. are mentioned.

The liquid crystal polyester used in the present invention is solvent-soluble, and the solvent-soluble means that it is dissolved in a solvent at a concentration of 1 mass % or more at a temperature of 50°C. The solvent will be described later.

As such a solvent-soluble liquid crystal polyester, it is preferable to contain, as the structural unit of the formula 3, a structural unit derived from an aromatic amine having a phenolic hydroxyl group and/or a structural unit derived from an aromatic diamine. That is, when the structural unit of formula 3 includes a structural unit (hereinafter referred to as "structural unit of formula 3'") represented by a structural unit in which at least one of X and Y is NH (formula 3'), there is a problem relative to the later-described structural unit. A suitable solvent (aprotic polar solvent) tends to be excellent in solvent solubility, and is therefore preferred due to this point. It is particularly preferred that substantially all of the structural units of formula 3 are structural units of formula 3'. In addition, the structural unit of the formula 3' is advantageous in that, in addition to sufficient solvent solubility of the liquid crystal polyester, the liquid crystal polyester has lower water absorption.

-X-Ar ³ -NH- (Formula 3')

(In the formula, Ar ³ and X have the same meanings as described above.)

More preferably, the structural unit of Formula 3 is contained in the range of 25 to 33 mol % with respect to the total content of all the structural units, so that the solvent solubility can be improved. In this way, the liquid crystal polyester having the structural unit of formula 3' as the structural unit of formula 3 also has the advantage that the solubility with respect to the solvent becomes better and a liquid crystal polyester film with low water absorption can be obtained.

It is preferable to contain the range of 30-80 mol% with respect to the total content of the structural unit of Formula 1 with respect to all structural units, and it is more preferable to contain the range of 35-50 mol%. The liquid crystal polyester containing the structural unit of Formula 1 at such a molar ratio tends to maintain sufficient liquid crystallinity and to be more excellent in heat resistance. Furthermore, considering the availability of the aromatic hydroxycarboxylic acid from which the structural unit of formula 1 is derived, p-hydroxybenzoic acid and/or 6-hydroxy-2-naphthoic acid are suitable as the aromatic hydroxycarboxylic acid.

The structural unit of Formula 2 is preferably contained in the range of 10 to 35 mol %, and more preferably contained in the range of 25 to 33 mol %, with respect to the total content of all the structural units. The liquid crystal polyester containing the structural unit of Formula 2 at such a molar ratio tends to maintain sufficient liquid crystallinity and to be more excellent in heat resistance. Furthermore, considering the availability of the aromatic dicarboxylic acid from which the structural unit of Formula 2 is derived, the aromatic dicarboxylic acid is preferably selected from terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid. At least one selected from the group consisting of.

In addition, since the obtained liquid crystal polyester can achieve higher liquid crystallinity, the molar ratio of the structural unit of Formula 2 and the structural unit of Formula 3 is represented by [Structural unit of Formula 2]/[Structural unit of Formula 3], preferably in the range of 0.9/1 to 1/0.9.

Next, the manufacturing method of the above-mentioned liquid crystal polyester is demonstrated.

The liquid crystal polyester can be produced by various well-known methods. In the case of producing a suitable liquid crystalline polyester, that is, a liquid crystalline polyester containing a structural unit of formula 1, a structural unit of formula 2, and a structural unit of formula 3, the monomers from which these structural units are derived are converted into ester-forming and amide-forming derivatives The method of producing a liquid crystalline polyester by polymerizing the product is preferable in terms of ease of operation.

The ester-forming and amidoamide-forming derivatives will be described by way of example.

Examples of ester-forming and amide-forming derivatives that are monomers having a carboxyl group such as aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids include those that promote the reaction to produce polyesters and polyamides. The carboxyl group becomes a highly reactive group such as acyl chloride, acid anhydride, or the like, or the carboxyl group forms an ester with alcohols, ethylene glycol, etc. in such a manner that polyester and polyamide are formed by transesterification and amide exchange reaction. group of substances, etc.

Examples of ester-forming and amide-forming derivatives that are monomers having a phenolic hydroxyl group such as aromatic hydroxycarboxylic acids and aromatic diols include polyesters and polyamides produced by transesterification. form, phenolic hydroxyl and carboxylic acids to form esters, etc.

In addition, amide-forming derivatives such as aromatic diamines, which are monomers having an amine group, include, for example, those in which amide groups and carboxylic acids form amides in a manner of producing polyamides by amide exchange reaction. material, etc.

Among them, in order to manufacture liquid crystal polyester more simply, the following method for manufacturing liquid crystal polyester is particularly preferable. Such a monomer having a phenolic hydroxylamine group is acylated to become an ester-forming/amide-forming derivative (hydric compound), and then the acyl group of the acyl compound and the carboxyl group of the monomer having a carboxyl group are combined in accordance with It is polymerized by transesterification and amide exchange to produce liquid crystal polyester.

The manufacturing method of such a liquid crystal polyester is described in Unexamined-Japanese-Patent No. 2002-220444 or Unexamined-Japanese-Patent No. 2002-146003, for example.

In the acylation, the addition amount of the fatty acid anhydride is preferably 1 to 1.2 times the equivalent, more preferably 1.05 to 1.1 times the equivalent, relative to the total of the phenolic hydroxyl group and the amino group. When the addition amount of the fatty acid anhydride is less than 1 times the equivalent, there is a tendency for the amides and raw material monomers to sublimate during the polymerization, which tends to block the reaction system, and when the amount exceeds 1.2 times the equivalent, the resulting liquid crystal polyester tends to change in color. a marked tendency.

It is preferable to react at 130-180 degreeC for 5 minutes to 10 hours, and it is more preferable to react at 140-160 degreeC for 10 minutes to 3 hours in the acylation.

From the viewpoints of cost and handling properties, the fatty acid anhydride used for acylation is preferably acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, or a mixture of two or more selected from these, and acetic anhydride is particularly preferred.

The subsequent acylation polymerization is preferably carried out at 130 to 400°C at a rate of 0.1 to 50°C/min, more preferably at 150 to 350°C at a rate of 0.3 to 5°C/min.

In addition, in the polymerization, the acyl group of the acyl compound is preferably 0.8 to 1.2 times the equivalent of the carboxyl group.

At the time of fermentation and/or polymerization, according to Le Chatelier-Brown's law (principle of equilibrium shift), in order to shift the equilibrium, by-product fatty acids, unreacted fatty acid anhydrides, etc. are preferably distilled into the system by evaporating them. outside.

In addition, it is also possible to carry out in the presence of a catalyst in the acylation and polymerization. As the catalyst, conventionally known catalysts for the polymerization of polyester can be used, and examples thereof include metals such as magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, and antimony trioxide. Salt catalyst; N,N-dimethylaminopyridine, N-methylimidazole and other organic compound catalysts.

Among these catalysts, heterocyclic compounds containing two or more nitrogen atoms, such as N,N-dimethylaminopyridine and N-methylimidazole, are preferably used (refer to JP-A-2002-146003 ).

The catalyst is usually charged together when the monomer is charged, and does not necessarily need to be removed after feration. Without removing the catalyst, the catalyst can be transferred from fermentation to polymerization as it is.

The liquid crystalline polyester obtained by such polymerization can be used as it is in the present invention, but in order to further improve properties such as heat resistance and liquid crystallinity, it is preferable to further increase the molecular weight, and among the above molecular weight, it is preferable to increase the solid phase polymerization. A series of operations involved in the solid-phase polymerization will be described. The low molecular weight liquid crystal polyester obtained by the above-mentioned polymerization is taken out, and pulverized into powder or flakes. Next, for example, in an atmosphere of an inert gas such as nitrogen, the pulverized liquid crystal polyester is subjected to a heat treatment in a solid phase state at 20 to 350° C. for 1 to 30 hours. By this operation, solid phase polymerization can be carried out. . The solid-phase polymerization may be performed while stirring, or may be performed in a state of standing without stirring. In addition, from the viewpoint of obtaining a liquid crystalline polyester having an appropriate flow initiation temperature described later, if the appropriate conditions for the solid-phase polymerization are described in detail, the reaction temperature is preferably over 210°C, and more preferably in the range of 220°C to 350°C. The reaction time is preferably selected from 1 to 10 hours.

The liquid crystal polyester used in the present invention preferably has a flow initiation temperature of 250°C or higher. If the flow start temperature of the liquid crystalline polyester is in this range, when a metal layer (electrode) having conductivity is formed on the layer containing the liquid crystalline polyester, there is a possibility that the layer containing the liquid crystalline polyester can interact with the liquid crystalline polyester. There is a tendency to obtain higher adhesion between the metal layers. The flow initiation temperature as used herein refers to a temperature at which the melt viscosity of the liquid crystal polyester becomes 4800 Pa·s or less under a pressure of 9.8 MPa in the evaluation of the melt viscosity by a flow tester. In addition, the flow onset temperature is well known to those skilled in the art as a measure of the molecular weight of liquid crystal polyesters (for example, see Naoyuki Koide, "Liquid Crystal Synthesis, Forming, and Application-" pp. 95 to 105, CMC (シーエムシー) , issued June 5, 1987).

The upper limit of the flow start temperature of the liquid crystalline polyester is determined by the range in which the liquid crystalline polyester can be dissolved in a solvent, but is preferably 350° C. or lower. If the upper limit of the flow start temperature is within this range, the viscosity of the liquid composition of the present invention will not increase significantly when the liquid-crystalline polyester is obtained, except that the solubility of the liquid-crystalline polyester with respect to the solvent is improved. The handleability of the composition tends to be better. In addition, in order to control the flow initiation temperature of the liquid crystal polyester within such an appropriate range, the polymerization conditions of the solid-phase polymerization may be appropriately optimized.

[Solvent]

The solvent used for dissolving the liquid crystal polyester is not particularly limited as long as it can dissolve the liquid crystal polyester, and examples thereof include N,N-dimethylacetamide, N-methyl-2-pyrrolidone , N-methylcaprolactamide, N,N-dimethylformamide, N,N-diethylformamide, N,N-diethylacetamide, N-methylpropionamide , dimethyl sulfoxide, γ-butyrolactone, dimethyl imidazolidinone, tetramethyl phosphamide and ethyl cellosolve acetate, as well as halogenated phenols such as p-fluorophenol, p-chlorophenol, perfluorophenol, etc. . These solvents may be used alone or in combination of two or more.

Among the above-mentioned solvents, from the viewpoint of handling, from N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactamide, N,N-dimethylacetamide Carboxamide, N,N-diethylformamide, N,N-diethylacetamide, N-methylpropionamide, dimethylsulfoxide, γ-butyrolactone, dimethylimidazole Aprotic polar solvents selected from the group consisting of linones, tetramethylphosphamide and ethyl cellosolve acetate are suitable.

The amount of the solvent used can be appropriately selected according to the type of solvent to be used as long as it is an amount for producing a liquid composition containing 0.1 mass % or more of the above-mentioned liquid crystal polyester, but the liquid crystal polyester is preferably a liquid crystal polyester relative to 100 parts by mass of the solvent. 0.5 to 50 parts by mass, more preferably 10 to 30 parts by mass.

When the liquid crystal polyester is less than 0.5 parts by mass, the viscosity of the liquid composition of the present invention tends to be too low and uniform coating cannot be performed, and when it exceeds 50 parts by mass, the viscosity tends to increase.

It should be noted that, in the liquid composition of the present invention, the liquid crystal polyester is preferably dissolved in the solvent (hereinafter, the liquid crystal polyester dissolved in the solvent is also referred to as "liquid crystal polyester precursor" in this specification. ”. It should be noted that the precursor of the liquid crystal polyester contains low molecular weight liquid crystal polyesters such as monomers and oligomers of the liquid crystal polyester), and the liquid composition is further diluted with the organic solvent to obtain In preparation, when the liquid crystal polyester is 0.5 g/dl solution, the intrinsic viscosity at 25° C. is 0.1-10.

[Liquid crystal polyester powder]

The liquid composition 1 of the present invention is a solution obtained by dissolving the above-mentioned liquid-crystalline polyester in the above-mentioned solvent, and further contains a liquid-crystalline polyester powder (LCP powder) in order to increase the solid content concentration.

The liquid crystal polyester powder of the present invention is a powder using the same or homologous liquid crystal polyester as the liquid crystal polyester dissolved in a solvent.

It should be noted that homology means a similar chemical structure in which the main skeletons of the unit structure or side chain functional groups have a partial repetition, etc. although the side chain functional groups of the unit structure and a part of the main skeleton of the unit structure are different, for example, As the homologous polyester, for example, compounds having a chemical structure having a plurality of carboxylic acid functional groups, such as phthalic acid, are referred to as homologous polyesters. In addition, the powder of the homologous liquid crystal polyester preferably shows compatibility with the liquid crystal polyester dissolved in a solvent.

By containing the powder of the same or homologous liquid crystal polyester as the solvent-soluble liquid crystal polyester, the solvent-soluble liquid crystal polyester (liquid crystal polyester precursor) can be compared with the same or homologous liquid crystal polyester at the time of production of the liquid crystal polyester film described later. The liquid crystal polyester powder does not show thixotropy, etc., and can be uniformly coated with a comma coater, etc. In addition, during the initial drying process after the coating (the residual solvent in the liquid composition 1 is about 4-30% range), the liquid crystal polyester precursor functions as a splicing agent for the liquid crystal polyester powder, thereby forming a film, and further, in the firing process performed after the drying process, the liquid crystal polyester powder is melted , while the liquid crystal polyester precursor undergoes a condensation reaction (polymerization), it is presumed that the liquid crystal polyester powder and the liquid crystal polyester precursor co-crystallize eventually.

The particle shape of the liquid crystal polyester powder (LCP powder) is preferably 0.01 μm to 1000 μm, and from the viewpoint of smoothness of firing into a film, 0.1 to 30 μm is preferable, and 0.1 to 10 μm is more preferable.

The compounding amount of the liquid crystal polyester powder (LCP powder) dispersed in the solution obtained by dissolving the liquid crystal polyester in the solvent is 100 parts by weight relative to the liquid crystal polyester precursor (liquid crystal polyester dissolved in the solvent) , LCP powder is 10 to 1000 parts by weight, preferably 10 to 800 parts by weight, and more preferably 60 to 300 parts by weight from the viewpoint of preventing shrinkage.

It should be noted that, in order to further increase the parts by weight, it is necessary to increase polar solvents such as NMP (N-methyl-2-pyrrolidone) in view of the mixing viscosity and the casting characteristics through the coating machine, which is important from the drying efficiency. , The cost of solvent cannot be said to be reasonable.

[Liquid crystal polyester film]

The liquid crystal polyester film 10 of the present invention is a film formed from the above-mentioned liquid composition 1, preferably has a water vapor transmission rate of 0.5 g/m ² ·24h or less, and the thickness of the liquid crystal polyester film is preferably 0.1 to 100 μm, more preferably 0.3 ~20μm.

In addition, by using the above-mentioned liquid composition 1 and forming it by a casting method, the liquid crystal polyester film 10 of the present invention can be non-oriented and not have the anisotropy that a general liquid crystal polyester film has, and can improve relative to the liquid crystal polyester film. Mechanical strength such as tensile force in the width direction.

In addition, regarding the compounding quantity of the liquid crystal polyester powder (LCP powder) contained in the liquid composition 1 used for formation of the liquid crystal polyester film 10, as mentioned above, with respect to the liquid crystal polyester precursor (solvent) Liquid crystal polyester in solvent) 100 parts by weight, LCP powder is preferably 10-800 parts by weight, more preferably 60-300 parts by weight.

It should be noted that, in order to further increase the parts by weight, it is necessary to increase polar solvents such as NMP (N-methyl-2-pyrrolidone) in view of the mixing viscosity and the casting characteristics through the coating machine, which is important from the drying efficiency. , The cost of solvent cannot be said to be reasonable.

[Manufacturing method of liquid crystal polyester film]

As a method for producing the liquid crystal polyester film 10 of the present invention, for example, a process including casting the liquid composition 1 of the present invention on a substrate and removing all the liquid composition from the substrate can be performed. The production is carried out by the so-called casting method of the solvent manufacturing process, and is not particularly limited as long as it is a casting method, but an example of a preferable production method is shown below.

First, the process of manufacturing the liquid crystal polyester film precursor 11 is performed. In the process of producing the liquid crystal polyester film precursor 11 , as shown in FIG. 1 , the liquid composition 1 of the present invention is cast from a coating machine 13 onto a substrate 15 , and the drying machine 14 is used at a predetermined temperature. The liquid composition 1 is dried for a predetermined time, and the liquid crystal polyester film precursor 11 in the state containing the residual solvent is formed into a film on the substrate 15 .

Moreover, as shown in FIG. 1, the 1st laminated body L1 in which the polyester film precursor 11 was laminated|stacked on the said base material 15 is wound up in roll shape.

Here, the liquid crystal polyester film precursor 11 refers to a film that, in the production process of the liquid crystal polyester film, is subjected to heat treatment (baking) at a stage ahead of the liquid crystal polyester film that is the final target Simultaneously with the removal of the residual solvent, the liquid crystal polyester (liquid crystal polyester precursor) in the residual solvent is polymerized (polymerized), whereby it can be turned into a film of a liquid crystal polyester film.

The base material 15 is not particularly limited as long as the liquid crystal polyester film precursor 11 can be peeled off, but preferably a glass plate, a stainless steel foil, a polyethylene terephthalate film, a polyethylene film, and a polypropylene film, polymethylpentene film, polytetrafluoroethylene sheet, etc.

In addition, as a method of casting the liquid composition 1 on the substrate 15, for example, a roll coating method, a gravure coating method, a knife coating method, a blade coating method, a bar coating method, a dip coating method, and a spray coating method can be mentioned. , a curtain coating method, a slit coating method, a screen printing method, etc. Among them, a knife coating method or a slit coating method is preferable from the viewpoint of easy control and the ability to uniformize the film thickness with high precision.

In addition, the temperature and time in drying the liquid composition 1 are not particularly limited. For example, the temperature is preferably 160°C or lower, more preferably 150°C or lower, and further preferably 140°C or lower. If the temperature is too high, there is a possibility that a defect will occur on the coating film surface. On the other hand, if the temperature is too low, the time required to remove the solvent becomes long, and there is a possibility that the productivity may decrease. Therefore, drying of the liquid composition 1 is preferably performed at least at 60°C or higher.

Moreover, it is preferable that it is 30-4 mass %, and, as for the residual solvent amount in the liquid crystal polyester film precursor 11, it is more preferable that it is 15-5 mass %. In addition, as long as this residual solvent amount is 18 mass % or less, it can suppress that adhesiveness arises on the surface of the liquid crystal polyester film precursor 11, and it is preferable in the point which can prevent mutual adhesion of films. In addition, as long as the residual solvent amount is 2 mass % or more, the film strength of the liquid crystal polyester film precursor 11 can be maintained. The resulting liquid crystal polyester film 10 can be prevented from being damaged when the base material 15 is peeled off, and further, when heat treatment (baking) in the third laminate manufacturing process described later is performed.

Next, after the above-described first laminate L1 is produced, the process proceeds to the second laminate production process, and as shown in FIG. After peeling off from the base material 15, the liquid crystal polyester film precursor 11 is transferred to the surface of the metal base material 16 having a rubber-like elastic layer on the surface. Then, the 2nd laminated body L2 in which the metal base material 16 was laminated|stacked on the back surface of the liquid crystal polyester film precursor 11 was obtained. Moreover, this 2nd laminated body L2 is wound in roll shape.

At this time, the metal base material 16 is laminated on the back surface of the liquid crystal polyester film precursor 11 (that is, the surface in contact with the base material 15 ). As long as the surface of the base material 15 is smooth, the liquid crystal polyester film front The back surface of the body 11 also becomes smooth, and the adhesiveness of the liquid crystal polyester film precursor 11 and the metal base material 16 can be ensured.

Here, as a material of the metal base material 16, aluminum, stainless steel, iron, copper, etc. are mentioned. Among them, stainless steel is particularly preferred from the viewpoint of strength and corrosion resistance.

In addition, it is preferable that the thickness of the metal base material 16 exists in the range of 20-200 micrometers. When the thickness of the metal base material 16 is 20 μm or more, the metal base material 16 has high resistance to scratches and is excellent in recyclability. When the thickness of the metal base material 16 is 200 μm or less, it becomes easy to wind up in a roll shape.

Moreover, as long as the adhesiveness with the liquid crystal polyester film precursor 11 and the peelability of the liquid crystal polyester film 10 in the film peeling process mentioned later can be ensured, the surface of the metal base material 16 can be given any surface treatment. For example, in order to make it difficult to peel the rubber-like elastic layer from the metal base material 16 , the surface of the metal base material 16 may be embossed.

Moreover, as a rubber-like elastic layer, a silicone-based rubber elastic layer, a fluorine-based rubber elastic layer, an acrylic-based rubber elastic layer, etc. are mentioned. Among them, the silicone-based rubber elastic layer is particularly preferred. If the silicone-based rubber elastic layer is used, the adhesiveness to the metal substrate 16 is good, and the peelability of the liquid crystal polyester film 10 in the film peeling process described later is also good.

The thickness of the rubber-like elastic layer is preferably in the range of 5 to 100 μm. When the thickness of the rubber-like elastic layer is 5 μm or more, the difference in elastic modulus of the metal base material 16 can be sufficiently alleviated. When the thickness of the rubber-like elastic layer is 100 μm or less, chipping of the rubber-like elastic layer can be prevented during processing of the metal substrate 16 .

In addition, the transfer method of the liquid crystal polyester film precursor 11 is not particularly limited, but as shown in FIG. 2 , from the viewpoint of improving productivity, it is preferable to sandwich the liquid crystal polyester film precursor 11 and the liquid crystal polyester film precursor 11 with a pair of rolls 19 . Metal substrate 16 .

Moreover, although it does not specifically limit as transfer temperature of the liquid crystal polyester film precursor 11, It is preferable to exist in the range of 10-200 degreeC. When the transfer temperature is 10° C. or higher, the adhesion to the metal substrate 16 will be good. When the transfer temperature is 200° C. or lower, the peelability of the liquid crystal polyester film 10 in the film peeling process described later will be favorable.

After the second layered body L2 is produced in this way, the process of manufacturing the third layered body L3 is shifted to, as shown in FIG. 3 , the rolled second layered body L2 is fed out, and the second layered body is heated at a predetermined temperature in a nitrogen atmosphere. L2 is continuously heat-treated (fired) in a heating furnace (firing furnace) 17 for a predetermined period of time. By this heat treatment, the third laminate L3 having the liquid crystal polyester film 10 and the metal base material 16 substantially free of solvent is obtained.

At this time, since the heat treatment of the second laminate L2 is performed in a nitrogen atmosphere, the deterioration of the liquid crystal polyester film 10 due to the oxidation of the liquid crystal polyester can be prevented beforehand.

Here, it is preferable that the heat processing temperature of the 2nd laminated body L2 exists in the range of 200-350 degreeC. When the heat treatment temperature is 200° C. or higher, the molecular weight of the liquid crystal polyester is increased (polymerized) by the heat treatment, and the properties as the liquid crystal polyester film 10 can be expressed from the liquid crystal polyester film precursor 11 . When the heat treatment temperature is 350° C. or lower, thermal decomposition of the liquid crystal polyester film 10 can be suppressed.

On the other hand, the heat treatment time of the second laminated body L2 is not particularly limited, but is usually heated to the above heat treatment temperature at a temperature increase rate of 10°C/min or less, and then maintained at the same temperature for 0 to 10 hours.

In addition, the method of heat treatment of the second laminate L2 is not particularly limited, except for the method of continuously passing through the heating furnace 17 by roll-to-roll (a method in which a raw material roll is supplied from a roll and the product is wound on a roll). For example, the method described in Japanese Patent Application Laid-Open No. 2008-207537 can be employed.

After the 3rd laminated body L3 is manufactured in this way, it transfers to a film peeling process, and as shown in FIG. 3, the liquid crystal polyester film 10 is peeled from the metal base material 16. At this time, since the rubber-like elastic layer is provided on the surface of the metal substrate 16 , that is, the surface on the liquid crystal polyester film 10 side, the liquid crystal polyester film 10 is easily peeled from the metal substrate 16 .

Here, the method of peeling off the liquid crystal polyester film 10 is not particularly limited, but as shown in FIG.

In addition, after the liquid crystal polyester film 10 is peeled off, if necessary, solvent cleaning, UV treatment, corona treatment, plasma treatment, flame treatment and other methods can be used to remove contaminants (silicone, containing fluorine substances, etc.).

By doing so, the liquid crystal polyester film 10 is peeled off from the metal base material 16, and the manufacturing process of the liquid crystal polyester film 10 is completed.

According to the method for producing the liquid crystal polyester film 10 described above, after the heat treatment is performed in a state in which the liquid crystal polyester film precursor 11 is transferred to the metal substrate 16 having the rubber-like elastic layer on the surface, the liquid crystal polyester film 10 is peeled off. .

It should be noted that in the production of the polyester film by the casting method as described above, by using the liquid composition 1 of the present invention, the drying time of the above-mentioned drying process and the firing time of the heat treatment process can be greatly reduced, and further , the foaming of the film during molding can be suppressed.

[Laminated film]

Next, the laminated film 20 of this invention is demonstrated.

The laminated film 20 of this invention is a film which has the liquid crystal polyester film layer 21 and the metal layer 26 which consist of the above-mentioned liquid composition 1 of this invention.

[Liquid crystal polyester film layer]

The liquid crystal polyester film layer 21 is a layer having a liquid crystal polyester film formed from the liquid composition 1 and having a liquid crystal polyester film having a moisture permeability of preferably 0.5 g/m ² · 24 h or less. As an example, it has a liquid crystal polyester film. 3～100μm thickness.

In addition, by forming the liquid crystal polyester film layer 21 of the present invention by a casting method using the above-mentioned liquid composition 1, the liquid crystal polyester film layer 21 of the present invention can be made non-oriented and does not have the anisotropy that a general liquid crystal polyester film has, and can improve the relative Mechanical strength such as tensile force in the width direction.

In addition, the liquid crystal polyester film layer 21 is configured to have a single-layer structure as shown in FIG. 4 , or a multilayer structure as shown in FIG. 5 (a three-layer structure in the figure).

In addition, as an example when the liquid crystal polyester film layer 21 has a multilayer structure, as shown in FIG. 5 , the liquid crystal polyester film layer 21 laminated on the surface of the metal layer 26 may have a filler added liquid crystal polyester On both sides of the filler-added layer 23 of the film, liquid crystal polyester layers 22 and 24, which are liquid crystal polyester films containing no fillers, are laminated (in this specification, for the sake of convenience, the reference numeral 22 is also referred to as a first liquid crystal polyester film). The ester layer, the symbol 24 is referred to as the second liquid crystal polyester layer.) three-layer structure.

Hereinafter, as shown in FIG. 5 , the liquid crystal polyester layers 22 and 24 and the filler addition layer 23 will be described.

[Liquid crystal polyester layer]

As shown in FIG. 5 , the liquid crystal polyester layers 22 and 24 are liquid crystal polyester films formed using the above-mentioned liquid composition 1 of the present invention, have a structure without filler, and preferably have a thickness of 0.5 g/m ² · 24 h or less. moisture permeability.

The compounding amount of the liquid crystal polyester powder (LCP powder) contained in the liquid composition used for the formation of the liquid crystal polyester layers 22 and 24 is, as described above, relative to the liquid crystal polyester precursor (liquid crystal polymer dissolved in a solvent) ester) 100 parts by weight, LCP powder is preferably 10-800 parts by weight, more preferably 60-300 parts by weight.

It should be noted that, in order to further increase the parts by weight, it is necessary to increase polar solvents such as NMP (N-methyl-2-pyrrolidone) in view of the mixing viscosity and the casting characteristics through the coating machine, which is important from the drying efficiency. , The cost of solvent cannot be said to be reasonable.

In addition, regarding the liquid crystal polyester layers 22 and 24, instead of the liquid composition 1 of the present invention, a liquid composition containing a solvent and a liquid crystal polyester dissolved in the solvent, which does not contain liquid crystal polyester film powder, can be used. In addition, even in the case where the liquid crystal polyester film powder is not contained, the liquid crystal polyester film can be produced by the casting method as in the case of the liquid composition containing the liquid crystal polyester film powder.

The thickness of the liquid crystal polyester layers 22 and 24 is preferably 0.3 to 20 μm.

In addition, if the thickness of the liquid crystal polyester layers 22 and 24 is made 1 μm or less, for example, there is a possibility that the unevenness of the surface unevenness of the laminated metal layer cannot be absorbed, and as a result, the dielectric loss may increase. The preferred thicknesses of the liquid crystal polyester layers 22 and 24 are 2 to 15 μm from the viewpoints of bonding with the metal layer 26 and maintaining dielectric properties.

In addition, the thickness of the liquid crystal polyester layers 22 and 24 is preferably formed so as not to exceed the thickness of the later-described filler addition layer 23 from the necessity of reducing the linear expansion coefficient of the entire liquid crystal polyester film layer 21. For example, it is formed as The thickness of the filler addition layer 23 is preferably 50% or less, more preferably 40% or less.

In addition, the thickness of the first liquid crystal polyester layer 22 and the thickness of the second liquid crystal polyester layer 24 may be different from each other.

In addition, it is not preferable to add an inorganic filler from the viewpoint of dielectric loss to the liquid crystal polyester layers 22 and 24 .

[filler added layer]

As shown in FIG. 5 , the laminate film 20 of the present invention is provided with a filler addition layer 23 composed of a liquid crystal polyester film to which an inorganic filler and a fluorine-based powder, which will be described later, are added, so that the linear expansion coefficient of the entire liquid crystal polyester film layer 21 can be reduced. , which is close to the linear expansion coefficient of the metal layer 26 laminated on the liquid crystal polyester film layer 21 .

The liquid crystal polyester film constituting the filler added layer 23 is formed of a material obtained by adding a filler described later to the liquid crystal composition 1 of the present invention. As the ester, it is preferable to use the same or the same type of liquid crystal polyester as the liquid crystal polyester layers 22 and 24 described above.

In addition, the filler added to the filler addition layer 23 is added to adjust the linear expansion coefficient of the entire liquid crystal polyester film layer 21 (mainly for the purpose of reducing the linear expansion coefficient), and an insulating inorganic filler is preferable. Silicon oxide, talc, silicon dioxide nitride, aluminum nitride, etc. Moreover, in addition to the said inorganic filler, you may add the fluorine type powder mentioned later. Hereinafter, first, the inorganic filler will be described.

The compounding ratio of the inorganic filler is in the range of 0.5 to 30 parts by mass with respect to 100 parts by mass of the solid content of the liquid crystal polyester, and from the viewpoint of maintaining the toughness of the finished film, it is preferably 1 to 15 parts by mass, and from the viewpoint of low dielectric constant, more preferably 0.5 to 7 parts by mass.

The average particle size of the inorganic filler used is 0.001 to 15 μm, and the thickness of the filler-added layer 23 is 0.05 to 3 μm, more preferably 0.05 to 1 μm, and the particle shape may be needle-like or other shapes other than spherical. , can also be amorphous.

In order for the obtained liquid crystal polyester film layer 21 to have a low dielectric constant as a whole, it is preferable to use a filler obtained by a combustion method such as fumed silica containing no moisture as such an inorganic filler.

It should be noted that powders of insulating inorganic substances produced by methods other than the above, such as wet pulverization method and normal pulverization method, may also be used as fillers, but in this case, in order to obtain fillers with a low water content, it is preferable to The powder is heated and dried at a temperature of 100°C to 400°C or higher for 30 minutes to 12 hours.

In addition, in the present invention, in addition to the above-mentioned inorganic fillers, a fluorine-based powder may be added to the filler addition layer 23 as a linear expansion modifier or an extender.

The fluorine-based powder refers to a powder of a composition containing fluorine in its composition, and preferably has hydrophobicity.

As the fluorine-based powder, for example, powder of PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxyalkane), and FEP (perfluoroethylene propylene copolymer) can be used. In addition, for example, a copolymer containing tetrafluoroethylene (component A) and a monomer (component B) mainly composed of an unsaturated hydrocarbon can be used (refer to FIG. 9 . In addition, R in the figure is preferably a hydrogen atom. , hydroxyl, organic group with hydroxyl, alkyl) fluorine-based powder.

In addition, what has a hydroxyl group can also be used as the monomer containing an unsaturated hydrocarbon as a main component. In addition, regarding the hydroxyl group, for example, the hydroxyl group participates in the ester bond accompanying the polymerization of the liquid crystal polyester forming the filler-added layer 23 , and the hydroxyl group falls off and becomes hydrophobic.

The powder particle size of the fluorine-based powder is preferably 0.01 to 5 micrometers (μm), but is not limited thereto. Moreover, as an average particle diameter of the said fluorine-type powder, 0.2-0.25 micrometer is especially preferable, but it is not limited to this.

In addition, the mixing ratio of the fluorine-based powder is in the range of 1 to 10 parts by mass, preferably 2 to 4 parts by mass, with respect to 100 parts of solid content of the liquid crystal polymer forming the filler addition layer 23 .

In addition, the compounding amount of the liquid crystal polyester powder (LCP powder) contained in the liquid composition 1 used for the formation of the filler-added layer 23 is relatively high from the viewpoint of uniform dispersion of the above-mentioned inorganic filler and fluorine-based powder. The amount of LCP powder is preferably 10 to 800 parts by weight, more preferably 60 to 300 parts by weight, based on 100 parts by weight of the liquid crystal polyester precursor (liquid crystal polyester dissolved in a solvent).

It should be noted that, in order to further increase the parts by weight, it is necessary to increase polar solvents such as NMP (N-methyl-2-pyrrolidone) in view of the mixing viscosity and the casting characteristics through the coating machine, which is important from the drying efficiency. , The cost of solvent cannot be said to be reasonable.

As described above, the filler is adjusted and added within the range of the above-mentioned addition amount, and the thicknesses of the liquid crystal polyester layers 22 and 24 and the filler added layer 23 are adjusted, thereby adjusting the linear expansion coefficient of the entire liquid crystal polyester film layer 21, For example, it is adjusted so that it may approach the linear expansion coefficient of the metal layer 26 laminated|stacked on the liquid crystal polyester film layer 21. In addition, for example, the difference between the coefficient of linear expansion of the metal layer 26 and the coefficient of linear expansion of the liquid crystal polyester film layer 21 may be adjusted so that the value of the coefficient of linear expansion of the liquid crystal polyester film layer 21 becomes the value of the metal layer. 125% or less of the coefficient of linear expansion of the layer 26 .

As an example, when the coefficient of linear expansion of the copper foil forming the metal layer 26 is 19 ppm, 25% of the coefficient of linear expansion is 4.75. In this case, adjustment can be made so that the linear expansion of the liquid crystal polyester film layer 21 may be adjusted. The coefficient is 23.75 ppm or less.

As described above, by making the linear expansion coefficient of the entire liquid crystal polyester film layer 21 close to the linear expansion coefficient of the metal layer 26 by the filler addition layer 23, the warpage of the entire laminate film 20 caused by the difference in the linear expansion coefficient can be further reduced. , deformation.

In addition, the laminated film 20 of FIG. 5 is covered with the liquid crystal polyester layers 22 and 24 formed of the unfilled liquid crystal polyester film via the filler added layer 23 on both sides (front and back), regardless of the hygroscopicity of the inorganic filler. In any case, the low water absorption of the original liquid crystal polyester film can be maintained, and the surface segregation of the filler can be prevented, the dielectric loss caused by the surface unevenness of the filler can be reduced, and the filler from the filler addition layer 23 can be prevented. shedding.

It should be noted that the surface of the filler-added layer 23 may be rough and dull due to the addition of the filler, but the liquid crystal polyester layers 22 and 24 without fillers are laminated on both sides of the filler-added layer 23 . The liquid crystal polyester film layer can be processed into a smooth and glossy beautiful surface.

In addition, in FIG. 5, the example in which the filler addition layer 23 is made into a single-layer structure is shown, but the filler addition layer 23 may be further made into a multilayer structure, and the addition amount of the filler may be changed for each layer, so that the filler added The addition amount has a gradient in the thickness direction.

In this case, in the configuration shown in FIG. 5 , it is preferable to employ an inclined structure in which the amount of filler added is reduced toward the first liquid crystal polyester layer 22 side and the second liquid crystal polyester layer 24 side.

[Metal layer]

As a raw material for the metal layer 26 constituting the laminated film of the present invention, various metals having electrical conductivity such as aluminum, iron, gold, silver, and alloys thereof other than copper and copper alloys can be used.

In addition, as the method for forming the metal layer 26 of the present invention, vacuum deposition and sputtering are used, and it is particularly preferable to use a vapor deposition method in which molecular energy is smaller and adhesion is weaker than sputtering.

Moreover, it is preferable that the thickness of the metal layer of this invention is 1-6 micrometers.

[Manufacturing method of laminated film]

Next, the manufacturing method of the laminated film 20 of this invention is demonstrated.

First, an example of the manufacturing method of the laminated|multilayer film 20 in which the liquid crystal polyester film layer 21 as shown in FIG. 4 is a single-layer structure is demonstrated.

First, as the base material 40, copper is vapor-deposited on one surface of an OPP (biaxially oriented polypropylene) film to form a copper foil (metal layer) 26 (a vapor deposition process, not shown).

It should be noted that the thickness of the OPP film 40 is 10 to 200 μm, preferably 25 to 50 μm, and the thickness of copper vapor deposition is preferably 1 to 6 μm.

In addition, the liquid composition 1 of the present invention (coating process, not shown) was cast on the surface of the copper foil 26 to be vapor-deposited by a coater, and the surface of the copper foil was coated with a dryer using a dryer. The liquid composition 1 is dried until the residual solvent is 4-30%, preferably 4-12% (drying process, not shown), and a liquid crystal polyester film precursor 31 is formed on the copper foil surface. Thereby, the laminated body in which the copper foil 26 and the liquid crystal polyester film precursor 31 were laminated|stacked on the OPP film 40 was obtained (OPP film 40/copper foil (metal layer) 26/liquid crystal polyester film precursor 31).

Here, the liquid crystal polyester film precursor 31 refers to a film obtained by heat treatment (baking) at a stage before the liquid crystal polyester film, which is the final target, in the production process of the liquid crystal polyester film as described above. ) to remove the residual solvent, and at the same time, the liquid crystal polyester (liquid crystal polyester precursor) in the residual solvent is polymerized (polymerized), whereby it can be turned into a film of a liquid crystal polyester film.

In addition, as a method of casting the above-mentioned liquid composition on copper foil, for example, a roll coating method, a gravure coating method, a knife coating method, a blade coating method, a bar coating method, a dip coating method, a spray coating method, a curtain coating method, a curtain coating method, and a curtain coating method are mentioned. Among them, the knife coating method or the slot T-die coating method is preferable because it is easy to control and can make the film thickness uniform with high precision.

In addition, in the drying process, if the drying temperature is too high, the liquid crystalline polyester precursor may start to polymerize before the firing process described later, and polymerization may occur, and defects may occur on the coating film surface. On the other hand, if If this temperature is too low, the time required to remove the solvent may be prolonged and productivity may decrease. The drying temperature is preferably 60°C or higher and 160°C or lower, more preferably 150°C or lower, and even more preferably 140°C or lower.

Next, the OPP film 40 was peeled off from the laminate (OPP film 40 / copper foil (metal layer) 26 / liquid crystal polyester film precursor 31 ) (peeling process, not shown) to obtain a laminate film precursor ( Liquid crystal polyester copper vapor deposition transfer film) 30.

Although it does not specifically limit as a peeling method of the OPP film 40, For example, there is a method of continuously peeling the OPP film 40 and the laminated film precursor 30 using a pair of peeling rolls.

Next, as shown in FIG. 6 , the laminate film precursor (copper foil 26/liquid crystal polyester film precursor 31) 30 produced through the above-mentioned OPP film peeling process is heated at a predetermined temperature with a firing furnace 51. The present invention having the liquid crystal polyester film layer 21 and the copper foil (metal layer) 26 is obtained by continuously heat-treating (continuous firing) for a predetermined period of time, whereby the liquid crystal polyester film precursor 31 becomes the liquid crystal polyester film layer 21 . The laminated film (copper foil 26/liquid crystal polyester film layer 21) 20 (firing process).

At this time, the inside of the firing furnace 51 is filled with nitrogen gas, and the heat treatment is performed in a nitrogen atmosphere, whereby the deterioration of the liquid crystal polyester film due to the oxidation of the liquid crystal polyester can be prevented beforehand. In addition, you may heat-process in the atmosphere of the inert gas (for example, helium, argon, etc.) other than the said nitrogen.

In addition, it is preferable to always blow the inert gas to the openings (gap) of the conveyance inlet and the conveyance outlet of the baking furnace 51 so that oxygen does not enter the inside of the baking furnace 51 .

In addition, the firing temperature (heat treatment temperature) of the laminated film precursor 30 is preferably in the range of 200 to 350°C. If the heat treatment temperature is 200° C. or higher, the heat treatment increases fusion bonding (anchoring) and intermolecular bonding at the interface between the liquid crystal polyester film layer 21 and the copper foil (metal layer) 26 , which can be embodied as a liquid crystal from the laminated film precursor 30 . Properties of the polyester film layer 21 . In addition, if the heat treatment temperature is 350° C. or lower, thermal decomposition of the liquid crystal polyester film can be suppressed.

In addition, in the firing furnace 51, gas nozzles (not shown) are alternately arranged above and below with respect to the advancing direction of the laminated film precursor 30 with the laminated film precursor 30 continuously conveyed therebetween. In the firing furnace 51 , the laminate film precursor 30 is held in a state where the tension acting on the laminate film precursor 30 is released (contactless conveyance), and the laminate film precursor 30 is held from above and below the laminate film precursor 30 . A gas (inactive gas) is blown from the gas nozzle toward the laminated film precursor 30, and the laminated film precursor 30 is moved up and down in a direction perpendicular to the conveying direction (the plane of the laminated film precursor) (vibration). ) at the same time as shipping. Thereby, as shown in FIG. 6, the said laminated|multilayer film precursor 30 in the baking furnace 51 is conveyed in the state which was suspended in the conveyance direction in a continuous substantially wavy shape, and is heat-processed at the same time.

As described above, the lamination film precursor 30 is moved up and down (vibrated) while heat treatment is performed, whereby first, the shrinkage reaction at the time of desolvation of the liquid crystal polyester film precursor 31 is alleviated, and the liquid crystal obtained by the heat treatment is There is intermolecular behavior between the layers of the polyester film layer 21 and the copper foil 26, and the interface between the liquid crystal polyester film layer 21 and the copper foil 26 has a complex structure. The range obtains the integration of the copper foil (metal) and the liquid crystal polyester film that cannot be peeled off and measured so that the anchor effect is obtained in the nano region (that is, the state in which the mutual adhesion and bonding strength are remarkably improved).

Further, generally, when a liquid crystal polyester film is produced from the liquid crystal polyester film precursor by heat treatment, shrinkage, warpage, deformation in the polymer, etc. occur, and the above-mentioned up-down movement during the heat treatment relaxes the film. The liquid crystal polyester film layer becomes non-oriented, and at the same time, the deformation in the polymer and the stress of the film are removed, and the laminated film of the present invention with the prepared liquid crystal polyester film layer does not shrink, warp, and deform the polymer. straighten.

Therefore, in order to prevent the occurrence of warpage, it is not necessary to use a clip tenter that has been used in the past.

In addition, the liquid crystal polyester film is relaxed by the above-mentioned up-and-down movement, thereby promoting the degassing of the solvent, removed water, other residues (including impure gas), etc. in the liquid crystal polyester polymer, preventing shrinkage or shrinkage of the film or the like. Foaming (desolventized bubbles) can prevent the generation of residual traces such as bubbles and pinholes.

It should be noted that the residues and impurities in the liquid crystal polyester polymer cause foaming. For example, when the laminated film 20 of the present invention is used as a flexible substrate (printed wiring board), it becomes an electronic device. The reason for the noise.

The height of the vertical movement of the laminated film precursor 30 in the above-mentioned firing furnace 51 is 3 mm to 900 mm, preferably 20 mm to 200 mm. The body 30 is suspended and conveyed without contact, and the height of the vertical movement of the laminated film precursor (the height of the wave) is 50 mm to 200 mm.

In addition, the installation interval of the gas nozzles is preferably 3 mm to 900 mm, more preferably 100 mm to 500 mm, and even more preferably 200 mm to 300 mm from the viewpoint of installation cost of the gas nozzles.

In addition, since the heat treatment is performed by far-infrared heating in the firing furnace 51, the liquid crystal polyester easily absorbs the far-infrared rays to the inside, so that the absorbed far-infrared rays (energy) excite the monomer or polymer and vibrate at the same time. Impure gases in the membrane are released (outgassed), which in turn moderates polymer deformation.

It should be noted that the wavelength range of infrared rays emitted by the far-infrared heater is approximately 3 to 25 μm, which corresponds to the wavelength range of thermal vibration (molecular vibration or lattice vibration) of almost all substances except metals.

As described above, the laminate film precursor 30 is subjected to heat treatment (baking process) to obtain the laminate film 20 having the copper foil (metal layer) 26 and the liquid crystal polyester film layer 21. Next, in order to improve the surface smoothness, The heating and calender 52 (150-200 degreeC) was continuously pressurized, and the winding was completed by cooling at room temperature.

In addition, the laminated film 20 which passed the said heating calender 52 can be pressurized by a press machine (not shown), and the said copper foil 26 and the liquid crystal polyester film layer 21 can be further press-bonded.

Next, an example of the manufacturing method of the laminated film 20 in which the liquid crystal polyester film layer 21 shown in FIG. 5 is a three-layer structure is demonstrated.

First, copper is vapor-deposited on the OPP (biaxially oriented polypropylene) film 40 as a base material to form the copper foil (metal layer) 26 .

It should be noted that the thickness of the OPP film 40 is 10 to 200 μm, preferably 25 to 50 μm, and the thickness of copper vapor deposition is preferably 1 to 6 μm.

In addition, the liquid compositions 1a to 1c forming the respective layers of the liquid crystal polyester film layer 21 were sequentially cast from a coating machine on the copper foil surface of the OPP film 40 by vapor deposition (coating process), and thereafter, the liquid compositions 1a to 1c were used in a drying machine. The residual solvent of each of the liquid compositions 1a to 1c coated on the copper foil 26 is dried to 4 to 30%, preferably 4 to 12%, and the liquid crystal polyester film precursors 31a to 31c are formed on the copper foil 26 film formation (drying process).

More specifically, as shown in FIG. 7, on the copper foil 26 vapor-deposited on the OPP film 40, first, the liquid composition of the present invention (as Also referred to as the first liquid composition for convenience) 1a, after casting, it is dried with a dryer 63a, and the liquid composition of the present invention containing the filler to form the filler layer 23 is applied thereon with a coater 61b. After casting the material (also referred to as the second liquid composition for convenience) 1b, it is dried with the dryer 63b, and further, the liquid composition on which the second liquid crystal polyester layer 24 is formed is applied with the coater 61c. After the material (also referred to as the third liquid composition for convenience) 1c is cast, it is dried with a dryer 63c, and after the above-mentioned process, the liquid crystal polyester film precursors 31a to 31c are prepared on the copper foil 26. film.

It should be noted that, regarding the method of casting the liquid composition 1 in the coating process and the drying temperature of the drying process, as in the above-mentioned manufacturing method of the laminated film 20 when the liquid crystal polyester film layer 21 is a single layer described in the description.

In addition, as shown in FIG. 8, on the copper foil 26 vapor-deposited on the OPP film 40, the above-mentioned three kinds of liquid compositions 1a to 1c The three layers are superimposed and cast at the same time, and the three layers are dried simultaneously with the dryer 63 .

Through the drying, the liquid compositions 1a to 1c of the respective layers on the copper foil 26 become liquid crystal polyester film precursors 31a to 31c containing residual solvent, and then the OPP film 40 is peeled off (OPP peeling process, Not shown), the laminated film precursor (liquid crystal polyester copper vapor deposition transfer film) 30 in which three layers of the liquid crystal polyester film precursors 31a to 31c were laminated on the surface of the copper foil (metal layer) 26 was obtained.

In addition, the laminated film precursor 30 is heat-treated in a heating furnace (firing furnace) (firing process, not shown), and the solvent of the liquid crystal polyester film precursors 31 a to 31 c is completely removed to obtain a liquid crystal with a three-layer structure. As for the polyester film layer 21, the laminated film 20 of the present invention as shown in FIG. 5 is produced.

It should be noted that the firing process may be the same as the firing process described in the above-mentioned manufacturing method of the laminated film 20 when the liquid crystal polyester film layer 21 is a single layer.

In the manufacturing method of the laminated film 20 of the present invention described above, as described above, the sputtering or vapor deposition of the copper foil is not performed after the firing of the liquid crystal polyester film, but is performed on the liquid crystal polyester film. Implemented before firing.

Thereby, first, the problem of pinholes generated by sputtering and vapor deposition of the metal foil can be solved. That is, when the liquid crystal polyester film is condensed during firing, the pinholes are closed by the metal foil following.

Furthermore, in the firing of the liquid crystal polyester film, high bonding with the sputtering interface of the metal foil is obtained together with thermal activity. For example, when the laminated film 20 of the present invention is used as a flexible substrate (printed wiring board), The metal layer 26 is resistant to micro-etching in subsequent processes.

In addition, in the film formation by the casting method as described above, by using the liquid composition 1 of the present invention, the drying time of the above-mentioned drying process and the firing time of the heat treatment process can be greatly reduced, and furthermore, the film formation during forming can be suppressed. of foaming.

In addition, as described above, the method for producing the laminated film 20 of the present invention does not form a film by flowing the liquid crystal polyester in a molten state in a certain direction as in the hot melt casting method, so that the liquid crystal polymer of the obtained laminated film 20 can be polymerized. The ester film layer is non-oriented, so-called common liquid crystalline polyester that is easily split in the orientation direction can be eliminated, and the anisotropy can be relieved to obtain a laminated film 20 that is less prone to warping, deformation, and the like.

In addition, when the liquid crystal polyester film layer 21 produced by the above method has a three-layer structure, not only the liquid crystal polyester layers 22 and 24 without fillers but also the filler-added layer 23 becomes non-oriented , excellent mechanical strength in any direction was confirmed.

In addition, by providing the filler-added layer 23 in the liquid crystal polyester film layer 21 of the laminated film 20, the linear expansion coefficient of the entire film is made close to the linear expansion coefficient of the metal layer (copper foil) 26, so that the entire laminated film 20 can be prevented from warping, On the other hand, the lamination surface with the metal layer 26 is the liquid crystal polyester layer 22 (or 24) without filler, so the adhesion between the liquid crystal polyester film layer 21 and the metal layer 26 will not be affected by the addition of the filler. loss, and further, low hygroscopicity is maintained, whereby the laminate film 20 can have a high function by exerting the advantageous properties of the liquid crystal polyester.

1: liquid composition 1a: 1st liquid composition 1b: Second liquid composition 1c: 3rd liquid composition 10: Liquid crystal polyester film 11: Liquid crystal polyester film precursor 13: Coating machine 14: Dryer 15: Substrate 16: Metal substrate 17: Heating furnace (firing furnace) 18: Peeling Roller 19: Roller 20: Laminated film 21: Liquid crystal polyester film layer 22: Liquid crystal polyester layer (1st liquid crystal polyester layer) 23: Filler Addition Layer 24: Liquid crystal polyester layer (2nd liquid crystal polyester layer) 26: Metal layer (copper foil) 30: Laminated film precursor 31 (31a, 31b, 31c): liquid crystal polyester film precursor 40: Substrate (OPP film) 51: Firing furnace 52: Heating calender 61 (61a, 61b, 61c): coating machine 63 (63a, 63b, 63c): Dryer L1: 1st laminated body L2: 2nd laminated body L3: 3rd laminated body

1 : is a process drawing which shows the manufacturing method of the liquid crystal polyester film 10 of this invention, and is a figure which shows the process of manufacturing the 1st laminated body L1. FIG. 2 is a diagram showing a manufacturing process from the first laminated body L1 to the second laminated body L2 in FIG. 1 . 3 : is a figure which shows the process of manufacturing the 3rd laminated body L3 from the 2nd laminated body L2 of FIG. 2, and peeling the liquid crystal polyester film 10. 4 is a schematic cross-sectional view showing the laminate film 20 of the present invention (the liquid crystal polyester film layer 21 is the laminate film 20 having a single layer). 5 is a schematic cross-sectional view showing the laminate film 20 of the present invention (the liquid crystal polyester film layer 21 is the laminate film 20 having a three-layer structure). FIG. 6 is a diagram showing an example of a method of manufacturing the laminated film 20 of FIG. 4 . FIG. 7 is a diagram showing an example of a method of manufacturing the laminated film 20 of FIG. 5 . FIG. 8 is a diagram showing an example of another manufacturing method of the laminated film 20 of FIG. 5 . FIG. 9 shows the chemical formula of an example of the fluorine-based powder.

20: Laminated film

21: Liquid crystal polyester film layer

26: Metal layer (copper foil)

Claims (13)

A liquid composition, characterized in that, in a solution containing a solvent and a liquid crystal polyester dissolved in the solvent, a liquid crystal polyester powder that is the same as or homologous to the liquid crystal polyester and has compatibility with the liquid crystal polyester is included to improve the performance of the liquid crystal polyester. Solid content concentration. The liquid composition according to claim 1, wherein the liquid crystal polyester powder is 10 to 1000 parts by weight with respect to 100 parts by weight of the liquid crystal polyester dissolved in the solvent. A liquid crystal polyester film, characterized in that the liquid crystal polyester film is formed from the liquid composition according to claim 1 or 2. The liquid crystal polyester film according to claim 3, wherein the liquid crystal polyester film is non-oriented. A method for manufacturing a liquid crystal polyester film, comprising: a process of casting the liquid composition of claim 1 or 2 on a substrate; and a process of removing a solvent from the liquid composition on the substrate. A laminated film comprising: a liquid crystal polyester film layer formed from the liquid composition according to claim 1 or 2; and a metal layer laminated on the surface of the liquid crystal polyester film layer. The laminate film according to claim 6, wherein the liquid crystal polyester film layer has a laminate structure in which a liquid crystal polyester layer without a filler is laminated on both surfaces of the filler-added layer to which the filler is added. The laminated film according to claim 7, wherein the filler is silicon dioxide, talc, silicon dioxide nitride, aluminum nitride or fluorine-based powder. A method for producing a laminated film, comprising: forming a metal layer on the surface of a substrate by vapor deposition or sputtering, casting and drying the liquid composition of claim 1 or 2 on the metal layer, and peeling off the A substrate, a process for producing a laminate film precursor having a metal layer and a liquid crystal polyester film precursor; and heat treatment of the laminate film precursor in a firing furnace to remove the liquid crystal polyester film precursor contained in the Residual solvent, manufacturing process of the laminated film having the metal layer and the liquid crystal polyester film layer. The method for producing a laminated film according to claim 9, wherein the base material is an OPP film, a CPP film, or an HPPE film. The method for producing a laminated film according to claim 9 or 10, wherein in the firing furnace, the laminated film precursor is made to be The heat treatment is performed with the upper and lower movable edges in the direction perpendicular to the horizontal plane of the laminated film precursor. The method for producing a laminate film according to claim 11, wherein in the firing furnace, the laminate film precursors are continuously conveyed across the laminate film precursor, with respect to the advancing direction of the laminate film precursor above and below. Gas nozzles are alternately arranged, and gas is blown from the gas nozzles to the laminated film precursor, so that the laminated film precursor moves up and down in a direction perpendicular to the horizontal plane of the laminated film precursor. A printed wiring board, wherein a conductor pattern is formed on a metal layer of the laminated film according to any one of claims 6 to 8.

Images