JP6182856B2 - Method for producing liquid crystal polymer film - Google Patents

Description

  The present invention relates to a method capable of efficiently producing a liquid crystal polymer film containing a high content of filler, and a liquid crystal polymer film produced by the method.

  Conventionally, a material obtained by reinforcing a thermosetting resin such as an epoxy resin with a non-woven fabric such as a glass cloth has been used as an electronic circuit board material. However, such a material has to be a rigid board. On the other hand, in recent years, a flexible substrate has been demanded, and polyimide is mainly used as the material thereof. However, polyimide exhibits hygroscopicity, and there is a problem that dimensional accuracy and electrical characteristics are deteriorated under high humidity.

  Recently, lead-free solder has been used for electronic circuit boards due to environmental problems. However, since reflow of lead-free solder requires a high temperature of about 260 ° C., a general resin cannot be used as a substrate material.

  Accordingly, attention has been focused on liquid crystal polymers as electronic circuit board materials. A liquid crystal polymer is a general term for polymers exhibiting liquid crystallinity in a molten state or a solution state, and has excellent heat resistance in addition to high solvent resistance, dimensional stability, electrical insulation and dielectric properties.

  However, the liquid crystal polymer has a problem that film formation is difficult. That is, since the liquid crystal polymer has a rigid molecular structure, it tends to be oriented in the molding direction to exhibit anisotropy or to tear in the molding direction. Thus, various devices have been devised for obtaining a film by molding a liquid crystal polymer.

  For example, in the technique of Patent Document 1, anisotropy is suppressed by laminating and supporting a liquid crystal polymer sheet oriented in the vertical direction obtained by T-die film formation on a fluorine-based heat-resistant film and laterally stretching. . In the technique of Patent Document 2, a liquid crystal polymer is extruded from a cylindrical die instead of a T die, and the film is obtained by immediately expanding the cylinder laterally by internal air pressure. These methods are classified as melt extrusion methods.

  In Patent Document 3, a liquid crystal polymer-polyimide resin alloy having a structure soluble in an aprotic polar solvent such as N-methyl-pyrrolidone or parachlorophenol is dissolved and cast on a support. A casting method is described in which the solvent is removed and then heat treated to release the support and produce a film.

  In Patent Documents 4 to 11, there are methods for injection molding or die molding of pellets obtained by molding a mixed powder obtained by dry blending a pulverized liquid crystal polymer and a filler with a tableting machine, or pellets obtained by melt-kneading. It is disclosed.

Japanese Patent No. 2921670 JP 2002-265804 A JP 2006-8976 A JP 2006-233118 A JP 2006-83239 A JP2012-21147A JP 2005-187696 A JP 2006-103099 A JP 2008-34724 A JP 2008-34725 A JP 2006-282678 A

  As described above, various methods are known for film-forming liquid crystal polymers that are difficult to mold. However, there has been no technique that can efficiently produce a thin and long liquid crystal polymer film with a high filler content.

  Specifically, the melt extrusion method is the most common resin molding method, and even when a liquid crystal polymer is used as a raw material, a relatively thin and long film can be produced. However, even if there is a description in the prior art document as to whether a high filler content is possible, in reality, if the filler content exceeds 25 vol%, the extruded molten resin mixture may be cut or cut. Even if it is not, there is a problem that only a film having a low degree of fullness and low strength can be obtained.

  According to the casting method, there is no such problem, and although a high content of filler can be blended, the liquid crystal polymer is insoluble in common solvents as it exhibits excellent solvent resistance, and is used for molding liquid crystal polymers. The extended law cannot be applied. In Patent Document 2, polyimide is added to form an alloy and then molded by a casting method. However, the properties derived from the liquid crystal polymer are reduced.

  Further, the filler can be blended in a high content even by an injection molding method or a mold molding method. However, these methods are suitable for forming relatively small and complicated shapes, and even if it can be locally thinned, they are not suitable for producing uniformly thin films or long films.

  Then, an object of this invention is to provide the liquid crystal polymer film obtained by the method which can manufacture efficiently the elongate liquid crystal polymer film which contains a high content and a filler, and the said method.

  The inventors of the present invention have made extensive studies to solve the above problems. As a result, if a mixed powder consisting of a liquid crystal polymer and a filler is heated and compression molded between two film-like heat-resistant substrates using a heating roll, there is no cutting at the time of molding even if the filler content is increased, The present invention was completed by finding that a thin and long liquid crystal polymer film can be produced very efficiently.

  The method for producing a liquid crystal polymer film containing a filler according to the present invention includes a step of obtaining a mixed powder of a liquid crystal polymer and a filler; a layer of the mixed powder between two film-like heat-resistant substrates. And a step of heat compression molding the laminate between a pair of heating rolls. The “liquid crystal polymer film” of the present invention refers to a film substantially composed of a liquid crystal polymer and a filler. In addition, a liquid crystal polymer film in which a film-like heat-resistant substrate is laminated on only one side, such as a “single-sided film-like heat-resistant substrate laminated liquid crystal polymer film”, is a liquid crystal polymer in which a film-like heat-resistant substrate is laminated on both sides The film is referred to as “double-sided film-like heat-resistant substrate laminated liquid crystal polymer film”.

  According to the method of the present invention, a liquid crystal polymer film containing a high content of filler can be efficiently produced. Specifically, unlike the melt extrusion method, even if the content of the filler in the liquid crystal polymer-filler mixed powder is 25 vol% or more, no tearing occurs at the time of molding.

  In the above-mentioned method of the present invention, when obtaining a mixed powder comprising a liquid crystal polymer and a filler, it is preferable to knead the molten liquid crystal polymer and filler after kneading. For example, when the filler is mixed with the powder obtained by pulverizing only the liquid crystal polymer, the liquid crystal polymer powder tends to be fibrous and entangled with each other, so the mixed powder is relatively poor in fluidity. Become. On the other hand, the mixed powder obtained as described above has high fluidity and has an advantage that a layer having a uniform thickness can be easily formed on a film-like heat-resistant substrate.

  In the above-described method of the present invention, a step of peeling at least one film-like heat-resistant substrate from the heat-compressed laminate may be performed. For example, when the film-like heat-resistant substrate does not have any function and only the liquid crystal polymer film is important, the film-like heat-resistant substrate on both sides may be peeled off. In addition, when the film-like heat-resistant substrate has some function, and the function can be sufficiently exhibited if one side is left, the film-like heat-resistant substrate having only one side may be peeled off. In this case, an effect peculiar to the present invention can be obtained that the step of forming the liquid crystal polymer film and laminating the functional base material layer thereon can be performed in a single step.

  According to the present invention, a method for producing a double-sided metal foil laminated liquid crystal polymer film in which metal foils are laminated on both sides includes a step of obtaining a mixed powder of a liquid crystal polymer and a filler; A step of forming a laminated body having a layer of mixed powder; and a step of heat compression molding the laminated body between a pair of heating rolls. According to this method, for example, in manufacturing a double-sided copper-clad laminate, a liquid crystal polymer film is formed, and separately prepared copper foils are bonded to both sides of the liquid crystal polymer film. Unlike conventional general manufacturing methods such as forming a double-sided copper-clad laminate by forming a copper layer using other physical vapor deposition methods, it is said that a liquid crystal polymer film is formed and a copper layer is laminated thereon The effect peculiar to the present invention that the process can be performed in a single process is obtained.

  The method for producing a single-sided metal foil laminated liquid crystal polymer film in which a metal foil is laminated on one side according to the present invention is a step of obtaining a mixed powder of a liquid crystal polymer and a filler; at least one is a metal foil 2 A step of forming a laminate having a layer of the mixed powder between one film-like heat-resistant substrate; a step of heat-compressing the laminate between a pair of heating rolls; and a layer subjected to heat-compression molding It includes a step of leaving at least one metal foil from the body and peeling off the other film-like heat-resistant substrate. According to this method, for example, in producing a single-sided copper-clad laminate, a liquid crystal polymer film is formed, and a copper foil prepared separately is attached to one side of this, or one side of the once formed liquid crystal polymer film is plated or Unlike the conventional general manufacturing method of making a single-sided copper-clad laminate by forming a copper layer using other physical vapor deposition methods, it is said that a liquid crystal polymer film is formed and a copper layer is laminated thereon The effect peculiar to the present invention that the process can be performed in a single process is obtained.

  The liquid crystal polymer film according to the present invention is a liquid crystal polymer film comprising a liquid crystal polymer and a filler, wherein the ratio of the filler to the whole is 25 vol% or more and the thickness is 500 μm or less. Thus, a thin liquid crystal polymer film with a high filler content has not existed conventionally.

  As the filler contained in the film of the present invention, those having an average aspect ratio of the surface portion of 1 or more and 4 or less and an average ratio of the major axis of the surface portion to the thickness of 10 or more are suitable. The liquid crystal polymer film blended with such a plate-like filler has relaxed orientation of liquid crystal polymer molecules, increased isotropic property, and reduced linear expansion coefficient, and linear expansion in the longitudinal and width directions. The ratio of the coefficients can be 0.6 or more.

  The average ratio of the major axis of the surface portion to the thickness of the plate filler is more preferably 50 or more. The liquid crystal polymer film blended with such a plate-like filler has a particularly reduced linear expansion coefficient, and the linear expansion coefficient in the longitudinal direction and the width direction are both 16 ± 3 ppm / ° C., for example, coated with a metal layer The difference between the linear expansion coefficient is small when it is made or laminated with a metal layer, warping due to the difference in linear expansion coefficient, and part of the metal foil for circuit formation from the metal foil laminated liquid crystal polymer film Or the dimensional change rate etc. of the liquid crystal polymer film part before and after metal foil removal in the case of removing all are reduced.

  The film of the present invention is preferably a long film. If a long liquid crystal polymer film is cut out as necessary to produce a product, the production efficiency is remarkably improved as compared with individual molding. In addition, it has been difficult to produce a thin and long liquid crystal polymer film with a high filler content by the conventional method, but according to the method of the present invention, such a film can be produced.

  The double-sided metal foil laminated liquid crystal polymer film and the single-sided metal foil laminated liquid crystal polymer film according to the present invention are characterized in that metal foils are laminated on both sides and one side of the liquid crystal polymer film according to the present invention, respectively. These laminated liquid crystal polymer films can be used as an electronic circuit board.

  According to the method of the present invention, a thin long liquid crystal polymer film containing a high content of filler, specifically, 25 vol% or more can be produced. Further, according to the method of the present invention, the production efficiency is very high because the steps of forming a liquid crystal polymer film and laminating a functional layer or the like can be performed simultaneously in a single step. In addition, the liquid crystal polymer film produced by the method of the present invention is thin but may have characteristics based on a high content of filler, such as high elastic modulus, high thermal conductivity, and high magnetic permeability. Moreover, the high content filler can suppress the defects of the liquid crystal polymer such as anisotropy and high linear expansion coefficient. Furthermore, since the liquid crystal polymer film according to the present invention can be produced in a long length, there is no need to individually mold it, for example, by an injection molding method or a mold molding method. Further shaping can be performed. In addition, since the liquid crystal polymer film according to the invention is a thin film, it is very useful as a material for an electronic member for an electronic device that has recently been aimed at further miniaturization, such as a mobile phone and a mobile terminal.

FIG. 1 is a schematic view of an example of an apparatus for continuously producing a long liquid crystal polymer film by the method of the present invention. In the figure, 1 represents a film roll, 2 represents a film-like heat-resistant substrate, 3 represents a powder spreader, 4 represents a heating roll, and 5 represents a liquid crystal polymer film.

  The method for producing a liquid crystal polymer film containing a filler according to the present invention includes a step of obtaining a mixed powder of a liquid crystal polymer and a filler; a layer of the mixed powder between two film-like heat-resistant substrates. And a step of heat compression molding the laminate between a pair of heating rolls. Hereinafter, the method of the present invention will be described in the order of execution.

(1) Step of obtaining mixed powder In the method of the present invention, a mixed powder comprising a liquid crystal polymer and a filler is prepared.

  The liquid crystal polymer includes a thermotropic liquid crystal polymer exhibiting liquid crystallinity in a molten state and a rheotropic liquid crystal polymer exhibiting liquid crystallinity in a solution state. Any liquid crystal polymer may be used in the method of the present invention, but a thermotropic liquid crystal polymer is preferably used because of excellent heat resistance and flame retardancy.

  Among the thermotropic liquid crystal polymers, thermotropic liquid crystal polyester (hereinafter simply referred to as “liquid crystal polyester”) is, for example, an aromatic compound mainly composed of aromatic dicarboxylic acid and monomers such as aromatic diol and aromatic hydroxycarboxylic acid. Polyester, which exhibits liquid crystal properties when melted. Typical examples thereof include type I [Formula (1)] synthesized from parahydroxybenzoic acid (PHB), terephthalic acid, and 4,4′-biphenol, PHB and 2,6-hydroxynaphthoic acid. Type II [Formula (2)] synthesized from the above, Type III [Formula (3)] synthesized from PHB, terephthalic acid, and ethylene glycol. Among them, type I liquid crystal polyester and type II liquid crystal polyester are more excellent in heat resistance. Therefore, when the liquid crystal polymer film produced by the method of the present invention is used for an electronic circuit board, for example, lead-free solder reflow. It is preferable to use type I liquid crystal polyester and / or type II liquid crystal polyester.

  A normal liquid crystal polymer is insoluble or hardly soluble in a general solvent. In the present invention, insoluble means that the solvent at 25 ° C. required to dissolve 1 g of the substance (liquid crystal polymer) is 10,000 mL or more, and hardly soluble means that the solvent is 1,000 mL or more, It means less than 10,000 mL. Further, as a solvent for dissolving the liquid crystal polymer, fluorine-containing phenol solvents such as pentafluorophenol, tetrafluorophenol, 3,5-bistrifluoromethylphenol are known, but such solvents are special and very expensive. Therefore, since it cannot be used industrially, it cannot be said that it is a general solvent. In addition, there are liquid crystal polymers that have a structure soluble in aprotic polar solvents such as N-methyl-pyrrolidone and parachlorophenol, and are soluble in aprotic polar solvents, but alloys with other resins such as polyimide, etc. Thus, the characteristics derived from the liquid crystal polymer have been reduced. In the present invention, a liquid crystal polymer that is insoluble or hardly soluble in a solvent is used.

  The form of the liquid crystal polymer used as the raw material is not particularly limited, such as powder and pellets, and a liquid crystal polymer that meets the production conditions of the mixed powder described later may be used as appropriate. For example, “E6MP” manufactured by Sumitomo Chemical Co., Ltd. may be used as the powdery liquid crystal polymer.

  The filler used as a raw material in the method of the present invention is not particularly limited, and either an organic filler or an inorganic filler can be used. As fillers, for example, mineral fillers composed of talc, mica, wollastonite, attapulgite, shirasu balloon, montmorillonite, activated clay, zeolite, sepiolite, zonotolite, etc .; copper, gold, silver, lead, iron, tungsten, stainless steel, aluminum, Metal filler made of nickel, alloy (Fe—Ni, Fe—Si, Fe—Si—Al, Fe—Si—Cr, Fe—Co, Fe—Si—B—Cr, etc.); silica Silicon filler composed of graphite, charcoal, carbon fiber, activated carbon, etc .; metal oxide filler composed of ferrite, zinc oxide, alumina, calcium oxide, magnesium oxide, titanium oxide, cerium oxide, etc .; barium sulfate , Gold consisting of potassium titanate, calcium carbonate, etc. Metal salt filler; organic filler made of aromatic polyamide, polyimide, etc. can be mentioned.

  What is necessary is just to select the kind of filler by the characteristic. That is, the properties of the filler are imparted to the liquid crystal polymer film, and the defects of the film consisting only of the liquid crystal polymer can be improved by the filler, so the filler is selected according to the purpose. Specifically, for example, according to the purpose such as improvement of elastic modulus, thermal conductivity, electrical conductivity, shielding / reflection of electromagnetic waves, improvement of defects derived from liquid crystal polymer such as anisotropy and high linear expansion coefficient, fillers Can be selected. Depending on the purpose, only one filler may be selected, or two or more fillers may be used in combination.

  The shape of the filler is not particularly limited, and a plate-like filler, a granular filler, a rod-like (needle-like) filler, an amorphous filler, or the like can be used.

  The plate-like filler has a shape having a face part facing each other and a side part between the face parts. For example, the average aspect ratio of the surface portion is 1 or more and 4 or less, and the average ratio of the major axis of the surface portion to the thickness is 10 or more. The surface portion may be curved.

  The particulate filler is spherical or substantially spherical. For example, the average ratio between the longest part and the shortest part is 1 or more and 2 or less.

  A rod-like (needle-like filler) means a rod-like material regardless of whether or not the surface is confirmed. For example, the average length of the length portion is about 0.5 μm or more and 300 μm or less, the average major axis of the cross section is about 0.05 μm or more and 15 μm or less, and generally the ratio of the length to the major axis of the cross section Means 5 or more.

  An amorphous filler has no uniform shape and includes various shapes.

  In addition, the shape in the definition of a filler is an enlarged photograph by a scanning electron microscope (SEM) or the like, and means a shape that can be confirmed by more than half of the fillers in the screen. Moreover, the average aspect ratio, average length, etc. in the definition of a filler shall mean the average value of 100 or more fillers which can be observed with the same enlarged photograph.

  Moreover, as an average particle diameter of the filler used by this invention, 1 micrometer or more and 100 micrometers or less are preferable as what is calculated | required from the particle size distribution measurement measured on a volume basis. However, for the average particle diameter, a commercially available filler is used, and when there is a catalog value, the catalog value may be referred to.

  As the filler used in the method of the present invention, a plate-like filler is suitable. Since the molecules of the liquid crystal polymer have a rigid linear structure, they are easily oriented by molding, and as a result, anisotropy occurs due to the coefficient of linear expansion, etc. It can be effectively reduced. In particular, if a plate-like filler having an average ratio of the major axis of the surface portion to the thickness of 50 or more is used, the linear expansion coefficient can be reduced to 16 ± 3 ppm / ° C. As a result, when a metal foil is used as the film-like heat-resistant substrate, the difference from the linear expansion coefficient is reduced, and warping of the film is suppressed.

  In the method of the present invention, a mixed powder of a liquid crystal polymer and a filler is prepared. In addition, according to this invention method, even if the ratio of the filler with respect to the whole is raised, a film can be favorably formed without tearing. Specifically, the ratio of the filler with respect to the whole mixed powder can be 25 vol% or more. The said ratio should just calculate as a ratio of the volume of a filler with respect to the total, measuring the volume of a liquid crystal polymer and a filler, without applying a pressure. In the present invention, the “mixed powder of liquid crystal polymer and filler” is not limited to a liquid crystal polymer and filler only in a strict sense. The following impurities may be included.

  The method for obtaining the liquid crystal polymer-filler mixed powder is not particularly limited, and general methods may be appropriately selected or combined. For example, a method in which a liquid crystal polymer is melted and then melted and mixed with a filler, and then pulverized. If the liquid crystal polymer is a powder, dry blending, a method in which conditions are adjusted so that the filler is not pulverized, and pulverized and mixed, ethanol, etc. And a method of pulverizing a mixture obtained by dispersing and mixing in an organic solvent. In the method of the present invention, it is preferable that the liquid crystal polymer is melted and melt-mixed with the filler and then pulverized. The mixed powder obtained under such conditions has high fluidity and is easy to form a layer with a uniform basis weight on a film-like heat-resistant substrate. Specifically, a powder excellent in fluidity with a degree of compression of 20% or less and an angle of repose of 45 ° or less is obtained. If the degree of compression is 20% or less, it is possible to sufficiently suppress an increase in the local spray amount. Moreover, if the angle of repose is 45 ° or less, bridges and clogging in the molding machine can be sufficiently suppressed.

  As a method of melting the liquid crystal polymer and mixing with the filler, a method of melt mixing and kneading at a temperature of about 200 ° C. or higher and 350 ° C. or lower using a twin screw extruder, a single screw extruder, a kneader, a mixer, or the like. Can be mentioned. Further, as means for pulverizing the composition obtained by melt mixing and kneading, media pulverizers such as freeze pulverizers, ball mills and planetary ball mills; airflow pulverizers such as jet mills and relative flow pulverizers; cutter mills , Impact mills such as blade mills, pin mills, and hammer mills.

  When mixing liquid crystal polymer powder and filler to obtain a mixed powder, a predetermined amount of liquid crystal polymer powder and filler are blended, and an airflow type pulverizer such as a jet mill or a relative flow pulverizer; a cutter mill, a blade mill These can be mixed using an impact pulverizer such as a pin mill or a hammer mill; a blender such as a V blender or a ribbon blender. By blending a predetermined amount of liquid crystal polymer powder and filler, dispersing in an organic solvent such as ethanol, mixing and drying, the mixture obtained by pulverization using the above pulverizer, mixer or pulverizer It can also be mixed.

  The particle size of the liquid crystal polymer-filler mixed powder may be adjusted as appropriate, but it is preferable to make it as small as possible in order to effectively perform heat compression molding between heating rolls. For example, it is set to 1000 μm or less. The particle size is preferably 800 μm or less, and more preferably 700 μm or less. The method for adjusting the particle size is not particularly limited. For example, if the liquid crystal polymer powder as a raw material or a fine filler is used, the pulverization conditions are adjusted, or coarse particles are removed with a filter or the like. Good.

(2) Step of obtaining a laminated body Next, a laminated body having a layer of the liquid crystal polymer-filler mixed powder is formed between two film-like heat-resistant substrates.

  The film-like heat-resistant substrate prevents sticking between the heating roll and the liquid crystal polymer when the liquid crystal polymer-filler mixed powder is heat-compressed into a film shape, or the pressure is uniformly applied to the mixed powder layer. It is for making. Accordingly, a material having excellent heat resistance, preferably having a thermal decomposition temperature or a heat distortion temperature of 400 ° C. or higher is used. Moreover, the functional base material laminated | stacked on a liquid crystal polymer film may be sufficient.

  Although the film-like heat-resistant substrate is used as a set of two sheets, the two may be the same as each other, or different ones may be used in combination.

  As the film-like heat-resistant substrate, for example, thermosetting resin films such as polyimide films; metal foils such as copper foil, aluminum foil, and stainless steel foil can be used. If a metal foil is used as a film-like heat-resistant substrate and it is not peeled off after heat compression molding, it can be a double-sided metal foil laminated liquid crystal polymer film, or at least one side of the metal after heat compression molding using a metal foil. A single-sided metal foil laminated liquid crystal polymer can be obtained by removing the other while leaving the foil. Moreover, if a film-like heat-resistant substrate having low adhesion to the liquid crystal polymer is used, peeling is easy even after heat compression molding.

  If the thickness of the film-like heat-resistant substrate is appropriately adjusted depending on the thickness of the target liquid crystal polymer film, whether to peel from the liquid crystal polymer film, the distance between heating rolls, the pressure during heat compression molding, etc. Well, although not particularly limited, for example, it can be 5 μm or more and 1 mm or less.

  The layer forming method of the liquid crystal polymer-filler mixed powder is not particularly limited. For example, one film-like heat-resistant substrate is kept horizontal, and the mixed powder is lined in the width direction of the film-like heat-resistant substrate. What is necessary is just to spread using the apparatus which can be dropped and spread in a shape.

  Examples of the apparatus for forming a liquid crystal polymer-filler mixed powder layer on a film-like heat-resistant substrate include an electromagnetic feeder having a rectangular trough, a vibration feeder such as a rubber spring feeder, and a mixed powder on a roller surface. Roller-type powder spreader that sprays after the body is fixedly attached, roller-type powder spreader that combines the roller and brush, powder spray that arranges nozzles for jetting mixed powder and gas in a row, rotating brush, Examples thereof include a powder spreader having a net and rubbing a rotating brush on the net to spread the mixed powder in a linear shape.

  The layer of the liquid crystal polymer-filler mixed powder needs to be uniform in order to make the thickness of the liquid crystal polymer film, which is the target, uniform. For this reason, it is preferable to adjust the operating conditions of the apparatus or to provide a blade or the like so that the basis weight of the layer is uniform.

  The basis weight of the liquid crystal polymer-filler mixed powder layer may be appropriately determined depending on the thickness of the target liquid crystal polymer film, whether or not the film-like heat-resistant substrate is peeled off, and the like.

  After forming the liquid crystal polymer-filler mixed powder layer on one film-like heat-resistant substrate, the other film-like heat-resistant substrate is stacked on the layer so as not to disturb the layer. A laminate having a layer of the above liquid crystal polymer-filler mixed powder is formed between the film-like heat-resistant substrates.

(3) Heat compression molding process Next, the laminated body of a film-like heat resistant base material and a liquid crystal polymer-filler mixed powder layer is heat compression molded between a pair of heating rolls.

  The kind of roll for heat compression molding is not particularly limited, and may be appropriately selected. For example, the heating method can be a heating medium heating method using a heating medium such as oil or water, an induction heating method, or the like. The surface is preferably subjected to a hardening treatment such as a hardening chrome treatment, a nitriding treatment, or a ceramic coating.

  What is necessary is just to set the conditions of heat compression molding so that the said mixed powder may fully be used as a film. For example, the temperature of the roll does not need to be higher than the melting point of the liquid crystal polymer because it is pressurized, but can be, for example, 250 ° C. or higher and 350 ° C. or lower. Further, the pressure can be set to 50 N / cm or more and 300 N / cm or less as a linear pressure applied to the laminate.

  In general, the surface of the liquid crystal polymer film is often separately laminated for protection. However, by carrying out this process using a film-like heat-resistant substrate for surface protection, it is possible to apply a protective film and form a film at the same time, and efficiently produce a liquid crystal polymer film with a protective film. it can.

  After passing through this step, the film-like heat-resistant substrate is laminated on both sides of the liquid crystal polymer film. In the case where the film-like heat-resistant substrate has some function, the film-like heat-resistant substrate may be left as it is without peeling and used as a functional film. When the functional layer only needs to be present on one side, or when only the liquid crystal polymer film needs to be obtained, one or both film-like heat-resistant substrates may be peeled off in the next step.

(4) Peeling step of film-like heat-resistant substrate Although it is optional, at least one film-like heat-resistant substrate may be peeled from the heat-compressed laminate. For example, to obtain a double-sided metal foil laminated liquid crystal polymer film with metal foil laminated on both sides, a metal foil may be used as both film-like heat-resistant substrates, or a single-sided metal with metal foil laminated on one side In order to obtain a foil laminated liquid crystal polymer film, a metal foil is used as at least one film-like heat-resistant substrate, and the other film-like heat-resistant substrate may be peeled off. Moreover, what is necessary is just to peel both film-like heat resistant base materials, when obtaining the liquid crystal polymer film which consists of a liquid crystal polymer containing a filler.

  The apparatus for peeling the film-like heat-resistant substrate is not particularly limited, and for example, a general protective film peeling apparatus can be used.

  According to the method of the present invention, the liquid crystal polymer mixed powder layer provided between the film-like heat-resistant substrates is subjected to heat compression molding, so that the liquid crystal polymer is blended with a high content of filler, or a thin liquid crystal polymer film is produced. Even in this case, it is possible to suppress the tearing of the film at the time of molding and the deterioration of the degree of completeness of the film obtained.

  For example, by adding a high amount of filler, specifically 25 vol% or more, high linear expansion coefficient and anisotropy, which are disadvantages of liquid crystal polymers, are reduced, and mechanical properties such as elastic modulus and dimensional stability are reduced. It becomes possible to improve the property. In addition, it can give properties such as thermal conductivity, conductivity, dielectric properties (high dielectric constant), electromagnetic wave reflection / absorption properties that liquid crystal polymers do not have, and can be used in circuit boards, antenna boards, component-embedded boards, and multilayer boards. It can be applied to a heat diffusion layer and an electromagnetic wave reflection / shielding layer.

  Further, according to the method of the present invention, a liquid crystal polymer film containing a high content of filler can be made thin. For example, a high filler content liquid crystal polymer film having a thickness of 500 μm or less can be produced, and further, a film having a thickness of 300 μm or less can be produced. Such a thin film high filler content liquid crystal polymer film is useful, for example, as an electronic circuit board material of an electronic device for which further miniaturization is aimed. However, since an excessively thin film may reduce productivity and strength, the thickness is preferably 10 μm or more.

  In particular, by blending 25 vol% or more of a plate-like filler having an average aspect ratio of the surface portion of 1 or more and 4 or less and an average ratio of the major axis of the surface portion to the thickness of 10 or more, High linear expansion coefficient and anisotropy, which are disadvantages, can be suppressed. Furthermore, if a plate-like filler having an average ratio of the major axis of the surface portion to the thickness of 50 or more is used, the linear expansion coefficient in the longitudinal direction and the width direction can both be 16 ± 3 ppm / ° C., for example, a metal layer When it is covered with a metal layer or laminated with a metal layer, the difference from the linear expansion coefficient is small, and the warp caused by the difference in linear expansion coefficient can be remarkably suppressed.

  From the above viewpoints, the liquid crystal polymer film according to the present invention is more specifically useful for, for example, high heat dissipation applications, metal replacement applications, electromagnetic wave reflection / shield applications, high precision parts (low dimensional changes), etc. Specifically, heat-radiating parts such as personal computers, liquid crystal projectors, mobile devices, mobile phones, shield members, or housings, other parts such as installation antennas that require shielding / reflecting properties such as electromagnetic waves in the field of information communication, automobile parts , Mechanical mechanism parts, outdoor installation equipment or building materials, high dimensional accuracy, electromagnetic wave reflection / shielding properties, barrier properties such as gas / liquid, heat and electrical conductivity, especially metal replacement for weight reduction etc. It is useful for automotive parts applications, electrical / electronic component applications, and thermal equipment component applications.

  Moreover, according to the method of the present invention, the steps of forming a liquid crystal polymer film and laminating a functional layer thereon can be performed in a single step. For example, when manufacturing a double-sided copper-clad laminate, a liquid crystal polymer film is formed, and a copper foil prepared separately is bonded to both sides of the film, or plating treatment and other physical vapor deposition methods are applied to both sides of the once formed liquid crystal polymer film. Unlike the conventional general manufacturing method of forming a double-sided copper-clad laminate by forming a copper layer using, a process of forming a liquid crystal polymer film and laminating a copper layer on this is a single step Can be done.

  The method of the present invention can be applied to the production of a long liquid crystal polymer film. Specifically, a long film-like heat-resistant substrate is used, one of which is horizontally fed, and a liquid crystal polymer-filler mixed powder layer is continuously formed thereon, and then the other film-like heat-resistant substrate. Cover the substrate. A continuous liquid crystal polymer film is produced by continuously passing the laminate between heated rolls and then peeling off at least one film-like heat-resistant substrate as necessary and winding it into a roll. Can do. If such a long film is cut or processed into a size corresponding to a product, the productivity is significantly improved as compared with the case where the final object is manufactured in a batch system.

  In the present invention, “long” means 5 m or more. Moreover, since the productivity increases as the produced film becomes longer, the length is preferably 10 m or more, more preferably 25 m or more, and further preferably 50 m or more. On the other hand, the upper limit is not particularly limited, but if it is excessively long, it may be difficult to wind up in a roll shape, so 1000 m or less is preferable, and 500 m or less is more preferable.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.

Production Example 1
Type II thermotropic liquid crystal polymer pellets (“C930RX” manufactured by Polyplastics Co., Ltd.) and the fillers shown in Table 1 in the ratio shown in Table 1 are twin screw extruders (“Twin Screw Extruder KZW15TW-45MG-” manufactured by Technobell). NH "), melted and mixed and kneaded, and extruded into a strand. The extruded strand was appropriately cut into a length of about 5 mm to obtain a mixed composition of a liquid crystal polymer and a filler.

  The obtained mixed composition was pulverized with a pin mill type impact pulverizer (“Sample Mill SAM T” manufactured by Nara Machinery Co., Ltd.). A liquid crystal polymer-filler mixed powder having a particle diameter of 700 μm or less was obtained using a metal mesh (φ700 μm perforated metal plate) installed at the exit of the pulverizer.

  Using the roll press machine schematically shown in FIG. 1, the liquid crystal polymer-filler mixed powder was continuously formed into a film. The roll press has an unwinding unit, a laminate forming unit, a heat compression molding unit (hot roll unit), and a winding unit. There are two unwinding shafts in the unwinding portion, and two sets of film-like heat-resistant substrates can be supplied. A powder spreader is installed in the layered product forming section so that the powder can be spread on the film-like heat-resistant substrate with a uniform basis weight. In the compression molding part, a pair (two) of induction heating rolls having a diameter of 350 mm are arranged vertically. The winding unit has a mechanism for peeling the film-like heat-resistant base material as necessary and a three-axis winding shaft, and the laminate can be wound regardless of whether the film-like heat-resistant base material is peeled off. .

  From the unwinding section of the roll press machine, two sets of two super heat / cold heat resistant polyimide films ("Kapton 100H" manufactured by Toray DuPont Co., Ltd., 25 μm thick) are supplied as the film-like heat-resistant substrate. The sheet was conveyed horizontally to the laminate forming part. In the laminate forming part, the liquid crystal polymer-filler mixed powder was uniformly dispersed on the film-like heat-resistant substrate using a powder spreader so as to have a basis weight corresponding to the target film thickness. . Next, the upper one of a set of two film-like heat-resistant substrates was superposed on the dispersed liquid crystal polymer-filler mixed powder. The obtained laminate was supplied to the compression molding part, and compression molded into a composite of a liquid crystal polymer film containing a filler and a substrate at the temperature and pressure shown in Table 1. Subsequently, in the film-like base material peeling part, both film-like heat resistant base materials were peeled.

  As a result, a filler was blended in an amount of 25 vol% or more with respect to the total mixed powder, and a long thin film having a thickness of 25 to 500 μm could be produced satisfactorily without occurrence of tearing.

Production Example 2
In the said manufacture example 1, instead of the polyimide film which is a film-like heat-resistant base material, copper foil ("FWJ-WS-12" by Furukawa Electric Co., Ltd., thickness 12 micrometers) was used, and both film-like heat resistance A double-sided copper foil laminated liquid crystal polymer film was produced in the same manner except that the conductive substrate (copper foil) was not peeled off. As in Production Example 1, no tearing or the like was observed.

Production Example 3
In Production Example 1, one set of two film-like heat-resistant substrates is copper foil (“FWJ-WS-12” manufactured by Furukawa Electric Co., Ltd., thickness 12 μm), and the other is a polyimide film (Toray DuPont). A single-sided copper foil laminated liquid crystal polymer film was produced in the same manner except that “Kapton 100H” (25 μm thickness) was used and only the polyimide film was peeled off after heat compression molding. As in Production Example 2, no tearing or the like was observed.

Test example 1
With respect to the single-sided copper foil laminated liquid crystal polymer film produced in Production Example 3, the characteristics and the like were evaluated under the following conditions.

(1) Measurement of solidity Cut out a 10cm x 10cm test piece from the center of each liquid crystal polymer film obtained, measure the distance between three sides with a caliper, and use a digital thickness gauge with a 2mmφ flat probe. The thickness was measured at five locations in the center and at the four corners, and the volume was calculated from the average value of each. The weight was measured using an electronic balance. The film density was calculated from the weight and volume of the test piece. Further, the solid density was calculated from the density of the liquid crystal polymer and the filler and the content of the filler. The degree of fulfillment was calculated as (film density / solid density) × 100 (%).

(2) Measurement of linear expansion coefficient Using a thermomechanical analyzer (TMA: Thermal Mechanical Analysis, manufactured by Seiko Denshi Co., Ltd.), the temperature of each liquid crystal polymer film obtained was increased to 230 ° C. at 40 ° C./min to cause strain. Then, the length of the sample was measured while lowering the temperature to 30 ° C. at 10 ° C./min, and the linear expansion coefficient was calculated from the displacement of 50 to 100 ° C. In the measurement of the linear expansion coefficient in MD (length direction) and TD (width direction), a test piece of 20 mm × 4 mm was cut out from the center of the film, placed on a TMA probe with a chuck distance of 10 mm, and a 5 g load was applied. And measured.

(3) Measurement of elastic modulus Using a punching die from the center of each liquid crystal polymer film obtained, it was punched into the shape of test piece type 5 described in JIS K7127, and a tensile tester (manufactured by AND) was used. Measured in conformity.

(4) Measurement of magnetic permeability Each liquid crystal polymer film cut into 10 cm × 10 cm so as to have a total thickness of 2 mm ± 0.3 mm was laminated by hot pressing at a temperature of 280 ° C. and a pressure of 1 MPa for 30 minutes. A ring-shaped test piece having an outer diameter of 7 mm and an inner diameter of 3 mm was cut out from the laminate using a YAG laser processing machine, and the magnetic permeability was measured with a magnetic permeability measurement system using a 16454A magnetic material measurement electrode. A measured value at a frequency of 13.56 MHz was used as a representative value.

(5) Measurement of thermal conductivity Each liquid crystal polymer film cut out to 10 cm × 10 cm so as to have a total thickness of 2 mm ± 0.3 mm was laminated by hot pressing at a temperature of 280 ° C. and a pressure of 1 MPa for 30 minutes. A test piece of 25 mm × 25 mm was cut out from the laminate, and the test piece was sandwiched between the upper and lower heaters and heated so as to have a one-dimensional heat flow with a temperature difference. The heat flux at this time was measured, and the thermal conductivity was determined from the thickness of the sample.

  Table 2 shows the measurement results of Test Examples 1 (1) to (5). In addition, the manufacture example numbers of the single-sided copper foil lamination | stacking liquid crystal polymer film manufactured on the conditions corresponded to the liquid crystal polymer film (production example numbers 1-26) manufactured by manufacture example 1 are set to 27-52. In Table 2, “MD (Y)” represents the linear expansion coefficient in the length direction, and “TD (X)” represents the linear expansion coefficient in the width direction.

  As shown in Table 2, a liquid crystal polymer film having a high degree of fullness was obtained by the method of the present invention when any filler was blended. However, when a granular filler and a rod-like filler were used, the linear expansion coefficient MD / The TD ratio was less than 0.6 and the anisotropy was high. On the other hand, in the liquid crystal polymer film containing the plate-like filler, the anisotropy was reduced with the MD / TD ratio being 0.6 or more.

  In particular, in a liquid crystal polymer film containing 25 vol% or more of a plate-like filler having an average ratio of the major axis of the surface portion to the thickness of 50 or more, the linear expansion coefficient of both MD and TD is 16 ± 3 ppm / ° C., copper Since the difference between the linear expansion coefficient of the copper foil is small, for example, when a single-sided copper foil laminated liquid crystal polymer film is subjected to thermal history such as lead-free solder reflow, the copper foil is used for circuit formation from the copper foil laminated liquid crystal polymer film. It is considered that the dimensional change rate of the liquid crystal polymer film portion before and after the removal when a part or all of the film is removed is remarkably suppressed.

Claims (6)

A method for producing a liquid crystal polymer film containing a filler, comprising:
Obtaining a mixed powder of liquid crystal polymer and filler;
Forming a laminate having a layer of the mixed powder between two film-like heat-resistant substrates; and
The manufacturing method characterized by including the process of heat-compressing the said laminated body between a pair of heating rolls.   The manufacturing method of Claim 1 which makes content of a filler in mixed powder 25 vol% or more.   The manufacturing method of Claim 1 or 2 which obtains mixed powder by grind | pulverizing, after melt-mixing the liquid crystal polymer and filler which were fuse | melted.   Furthermore, the manufacturing method in any one of Claims 1-3 including the process of peeling at least one film-like heat-resistant base material from the laminated body heat-molded. A method for producing a double-sided metal foil laminated liquid crystal polymer film in which a metal foil is laminated on both sides,
Obtaining a mixed powder of liquid crystal polymer and filler;
Forming a laminate having the mixed powder layer between two metal foils; and
The manufacturing method characterized by including the process of heat-compressing the said laminated body between a pair of heating rolls. A method for producing a single-sided metal foil laminated liquid crystal polymer film in which a metal foil is laminated on one side,
Obtaining a mixed powder of liquid crystal polymer and filler;
Forming a laminate having a layer of the mixed powder between two film-like heat-resistant substrates, at least one of which is a metal foil;
A step of subjecting the laminate to heat compression molding between a pair of heating rolls; and
The manufacturing method characterized by including the process of leaving at least 1 sheet of metal foil from the laminated body heat-press-molded, and peeling the other film-like heat resistant base material.

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