JP2008075079A - Method for producing liquid crystal polymer composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a liquid crystal polymer composition in which the coefficient of volume expansion is reduced and the aggregation of inorganic fillers is suppressed so as to maintain the strength. <P>SOLUTION: The method for producing the liquid crystal polymer composition according to the present invention comprises the steps of introducing a functional group capable of binding to a monomer that composes a liquid crystal polymer molecule onto the surface of an inorganic filler and mixing the inorganic filler on which the functional group has been introduced with the monomer that composes the liquid crystal polymer molecule so as to subject the thus obtained mixture to a polymerization reaction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a liquid crystal polymer composition.

  In recent years, liquid crystal polymers have attracted attention as relatively new resin materials. The liquid crystal polymer is useful as a super engineering plastic because it is excellent in heat resistance and flame retardancy and exhibits high strength and high elastic modulus. In particular, liquid crystal polymers have excellent dielectric properties such as low dielectric loss, and are expected to be used as insulator materials for electronic circuit boards.

  However, when the liquid crystal polymer is a sheet or film, there is an anisotropy problem that the properties differ depending on the direction depending on the molding method. That is, the liquid crystal polymer molecule is a rigid linear molecule, exhibits liquid crystallinity in a molten state or a solution state, and undergoes molecular orientation in that direction when subjected to shear stress. As a result, since there are differences in characteristics between the length direction of the liquid crystal polymer molecule and the direction perpendicular thereto, anisotropy occurs between the direction in which the molecules are aligned and the other direction. Therefore, for example, in the case of film forming by extrusion, the liquid crystal polymer molecules are oriented in the extrusion direction, so that there is a problem that physical properties are different between the extrusion direction and the orthogonal direction, and the film is easily torn in the extrusion direction. In addition, the coefficient of thermal expansion (hereinafter referred to as “CTE”) is one of the characteristics in which the value differs greatly depending on the direction in the liquid crystal polymer because it is small in the alignment direction of the liquid crystal polymer molecules and large in the orthogonal direction.

  In order to solve the problem of anisotropy, a method has been devised in which, after extrusion molding, the film is further stretched in a direction perpendicular to the extrusion direction, or blown. According to these methods, in the film plane, it is possible to perform molecular orientation not only in the extrusion direction but also in a direction perpendicular thereto, and as a result, the molecular orientation in the planar direction becomes more random, and the anisotropic in the planar direction. Can be reduced. As a result, the problem of “easy tearing” in the extrusion direction of the sheet made of a liquid crystal polymer can be improved. Further, since the liquid crystal polymer molecules are aligned in the planar direction by stretching or the like, the CTE in the planar direction can be controlled to be relatively low. However, problems still remain with these methods.

  That is, when a liquid crystal polymer film is used as an insulator material for an electronic circuit board, the CTE in the planar direction is controlled to be small according to the CTE of the conductor layer for the electronic board circuit. The conductor layer of an electronic circuit board is usually formed by laminating a copper foil on an insulating film plane such as a liquid crystal polymer, or sputtering, vapor deposition or plating of copper, but the CTE of copper is 16 to 17 ppm. This is because the CTE of the liquid crystal polymer film is reduced to reduce the warpage caused by the difference between the CTEs. Moreover, in recent years, it has become necessary to reduce the CTE in the thickness direction of the liquid crystal polymer film. However, this problem has not been solved sufficiently.

  In recent years, in the field of electronic circuit boards, there has been a demand for lighter and thinner circuit boards because of demands for smaller and lighter electronic devices. Furthermore, it is necessary to increase the density of circuit boards in order to increase the information to be transmitted and received and to increase the speed. Therefore, multilayer circuit boards are used to transmit and receive electrical signals not only in the planar direction of the circuit board but also in the thickness direction.

Here, the volume expansion coefficient of a substance shows a fixed value as a value peculiar to each substance. This volume expansion coefficient can be considered as the sum of three-dimensional thermal linear expansion coefficients orthogonal to each other as shown in the following formula 1.
Formula 1: Volume expansion coefficient = (thermal linear expansion coefficient) _A component + (thermal linear expansion coefficient) _B component + (thermal linear expansion coefficient) _C component [In the above formula, A, B, and C are three-dimensional direction axes orthogonal to each other. Show]

In the extruded film, the relationship expressed by the above equation 1 is that the volume expansion coefficient is CTE _vol , the thermal linear expansion coefficient in the film extrusion direction (length direction) is CTE _x , When the thermal linear expansion coefficient in the width direction of the film is CTE _y , and the thermal linear expansion coefficient in the direction orthogonal to the film thickness direction, that is, the thickness direction of the film is CTE _z , the following expression 2 is expressed.
Formula 2: CTE _vol = CTE _x + CTE _y + CTE _z
[In the above formula, x, y, and z indicate directions orthogonal to each other.]

As described above, since CTE _vol is a constant value inherent to a substance, the total value of CTE _x , CTE _y and CTE _z is always the same. Therefore, if the CTE in the planar direction is reduced by a method such as stretching, it can be easily understood that the CTE in the thickness direction is increased. This becomes a very big problem in a multilayer electronic circuit board.

  More specifically, as described above, the CTE of the liquid crystal polymer is small in the alignment direction of the liquid crystal polymer molecules and large in the orthogonal direction. When a liquid crystal polymer is extruded, the liquid crystal polymer molecules are strongly molecularly oriented in the film extrusion direction, and are almost oriented in the direction perpendicular to the extrusion direction in the film plane, that is, in the film width direction and the film thickness direction. Not done. According to the stretching method and the inflation method described above, it is possible to align molecules only in the width direction of the film among the two directions in which the molecules are not aligned. Therefore, the alignment in the plane direction of the liquid crystal polymer molecules is the extrusion direction and the width direction. Therefore, the CTE in the planar direction can be reduced. However, in these methods, the molecules cannot be oriented in the thickness direction, and the CTE in the thickness direction is rather high due to the relationship shown in Equation 2 above. As a result, in the multilayered electronic circuit board, the CTE of the liquid crystal polymer film that is an insulator and the copper forming the circuit is extremely different in the thickness direction, and the circuit board is manufactured or actually used. Due to the temperature change in the circuit, the circuit breaks or cracks in the thickness direction of the substrate.

  There exists a thing of patent document 1 as a technique for eliminating CTE with the high thickness direction of a liquid crystal polymer film. In this technique, a liquid crystal polymer is blended with a thermoplastic resin such as polyethersulfone to reduce CTE in the thickness direction of the film. However, the CTE of copper mainly used as a circuit material is 16 to 17 ppm / ° C., whereas the CTE in the thickness direction achieved by the technology is said to be “not exceeding 270 ppm”. The effect is not enough. Further, if other thermoplastic resins are blended, there is a possibility that the characteristics of the liquid crystal polymer cannot be fully utilized.

The technique of Patent Document 2 discloses a liquid crystal polymer composition to which a porous inorganic filler having an average pore diameter of 10 to 500 mm is added in order to improve the anisotropy and strength in the planar direction. In addition, in order to improve the dispersion stability of inorganic particles such as titanium dioxide, a technique for producing inorganic / polymer composite particles by suspension-polymerizing inorganic particles surface-treated with organic substances together with monomers is disclosed in Patent Literature. 3.
JP 2004-175959 A (Claims) JP-A-2-284952 (Claims, upper left column on page 2, lower right column on page 3) Japanese Patent Laying-Open No. 2003-73407 (Claims, paragraph 0007)

As described above, the technology for eliminating the molecular orientation anisotropy in the planar direction of a liquid crystal polymer film or the like and using it to control the CTE in the planar direction to a small level has reached a practical level. Moreover, in order to reduce the CTE in the thickness direction, it is known to add an inorganic filler having a CTE _vol smaller than that of the liquid crystal polymer, and according to this technique, the CTE in the thickness direction can be substantially reduced. it is conceivable that.

  However, when an inorganic filler is added to the liquid crystal polymer, the affinity of the inorganic filler for the liquid crystal polymer is low, so that the inorganic filler tends to aggregate in the liquid crystal polymer matrix, resulting in a problem that the strength of the resulting composition is reduced. Further, in order to increase the effect of adding the inorganic filler, it is necessary to add a large amount of filler. In this case, particularly in the case of the thermotropic liquid crystal polymer, the fluidity in the molten state is remarkably lowered, and extrusion molding becomes difficult.

  Patent Document 3 describes a technique for polymerizing a monomer in the presence of an inorganic filler and bonding the polymer to the inorganic filler in order to increase the dispersion stability of the inorganic filler in the polymer. However, the monomer described in Patent Document 3 is only a monomer capable of radical polymerization such as acrylate, and there is no description or suggestion regarding the liquid crystal polymer.

  A strong magnetic field was used as an attempt to reduce the CTE by aligning liquid crystal polymer molecules in the thickness direction of the film, in addition to mixing components other than the liquid crystal polymer, such as resins and inorganic fillers, having a CTE smaller than the liquid crystal polymer. A method is being considered. However, in this method, it is necessary to expose the liquid crystal polymer to a strong magnetic field such as a superconducting magnet for a long time. In particular, a thermotropic liquid crystal polymer is difficult to process in large quantities because the liquid crystal polymer molecules need to be kept at a high temperature exhibiting liquid crystallinity, and is not practical because it lacks continuous productivity.

  Accordingly, the problem to be solved by the present invention is to provide a method for producing a liquid crystal polymer composition in which the volume expansion coefficient is reduced, the aggregation of inorganic fillers is suppressed, and the strength is maintained.

In order to solve the above problems, the present inventors first reduced the volume expansion coefficient (CTE _vol ) of the material obtained by adding the inorganic filler, and as a result, the direction perpendicular to the molding direction (hereinafter referred to as “thickness direction”). In some cases, the CTE of the liquid crystal polymer composition was reduced. Furthermore, the dispersibility of the inorganic filler in the liquid crystal polymer matrix was improved by bonding liquid crystal polymer molecules to the surface of the inorganic filler. As a result, the liquid crystal polymer molecules bonded to the inorganic filler are probably oriented in the thickness direction, but the CTE in the thickness direction can be further improved. In addition, if a porous inorganic filler is used, the binding force between the liquid crystal polymer and the inorganic filler is probably due to the anchor effect, but the dispersibility of the inorganic filler and the strength of the liquid crystal polymer composition itself are improved. As a result, the present invention has been completed.

  The method for producing a liquid crystal polymer composition according to the present invention includes a step of introducing a functional group having a binding ability with a monomer constituting a liquid crystal polymer molecule on the surface of a porous inorganic filler; A step of mixing a porous inorganic filler and a monomer constituting a liquid crystal polymer molecule, and subjecting the obtained mixture to a polymerization reaction.

  As the porous inorganic filler, those having a ratio of pores having a diameter of 2 to 100 nm to all pores of 80% or more are suitable. If a porous filler having pores of an appropriate diameter is used, the surface modifier enters into the pores, resulting in the ability to bind to the monomer, and the liquid crystal polymer molecules extend from there to expand the inorganic filler and the liquid crystal polymer molecules. Bonding power can be increased. In addition, even in the case of liquid crystal polymer molecules that are not bonded to the pore inner surface, the molecular chain grows in the pore space, and the liquid crystal polymer apparently enters the pores, resulting in a physical “fitting” state. The anchor effect is more effectively exhibited. As a result, the strength of the liquid crystal polymer composition is further increased. Such an effect is exhibited particularly in the case where the ratio of pores having a diameter of 2 to 100 nm is large. If the diameter of the pore is 2 nm or more, the surface modifier and the monomer molecule can easily enter the pore, and if it is 100 nm or less, the bonding force between the liquid crystal polymer molecule and the inorganic filler can be maintained.

As the porous inorganic filler, those having a pore volume of 2 to 100 nm in diameter of 0.002 cm ³ / g or more are also suitable. Even with a porous inorganic filler having an appropriate pore diameter distribution, the above-described effects cannot be sufficiently expected with an inorganic filler having an extremely small pore volume. However, if the pore volume having a diameter of 2 to 100 nm is 0.002 cm ³ / g or more, the effect of improving the binding force between the liquid crystal polymer molecule and the porous inorganic filler can be sufficiently exerted.

  In the method of the present invention, it is preferable to mix the porous inorganic filler into which the functional group is introduced and the monomer constituting the liquid crystal polymer molecule in the presence of acetic anhydride or acetic acid. Acetic anhydride and acetic acid have an appropriate dispersing or dissolving ability with respect to the monomer and the like, and also have a function of activating the functional group of the monomer by acylation, have a relatively low boiling point, and can be easily removed. There is also an advantage that coloring is difficult to occur. Furthermore, the effect of increasing the reactivity by activating the functional group of the monomer can be expected.

  The material of the porous inorganic filler is preferably one or more selected from the group consisting of silica, alumina, alumina silica, zeolite, glass, aluminum nitride, calcium carbonate, shirasu, and diatomaceous earth.

  In the liquid crystal polymer composition according to the present invention, although the inorganic filler is blended, the aggregation of the inorganic filler is suppressed and the strength is not reduced due to the aggregation of the filler. In addition, the CTE not only in the plane direction but also in the thickness direction is significantly reduced as compared with the conventional liquid crystal polymer composition. Therefore, even when used as an insulator of a multilayered electronic circuit board, disconnection of the circuit in the thickness direction can be prevented. Accordingly, the liquid crystal polymer composition produced by the method according to the present invention can be used as an insulator for electronic circuit boards, etc., which have recently become increasingly demanding particularly for CTE due to an increase in information to be transmitted and received. It is extremely useful.

  The method for producing a liquid crystal polymer composition according to the present invention includes a step of introducing a functional group having a binding ability with a monomer constituting a liquid crystal polymer molecule (hereinafter referred to as “surface modification step”) on the surface of the porous inorganic filler. ); And a step of mixing the porous inorganic filler into which the functional group has been introduced and the monomer constituting the liquid crystal polymer molecule (hereinafter referred to as “mixing step”), and subjecting the resulting mixture to a polymerization reaction (hereinafter referred to as “ A polymerization step) ”. Hereinafter, the method of the present invention will be described in the actual order of implementation.

(1) Surface Modification Step The porous inorganic filler used in the method of the present invention can be used without particular limitation as long as it has a low coefficient of thermal expansion and can reduce the coefficient of thermal expansion of a molded body made of a liquid crystal polymer. The material of the porous inorganic filler is silica, alumina, alumina silica, zeolite, glass, titanium oxide, zinc oxide, potassium titanate, barium titanate, strontium titanate, aluminum nitride, aluminum borate, calcium silicate, silica Examples thereof include aluminum oxide, talc, clay mica, shirasu, and diatomaceous earth, and silica, alumina, alumina silica, zeolite, glass, aluminum nitride, calcium carbonate, shirasu, and diatomaceous earth are particularly preferable because of their high convenience. Can be used.

The size of the porous inorganic filler is preferably about 0.1 to 500 μm as an average particle diameter measured by a laser diffraction scattering method. This is because if the average particle size is 0.1 μm or more, the CTE reduction effect by adding filler can be more reliably exhibited, and if it is 500 μm or less, the homogeneity of the material is further increased. In addition, the average particle diameter in this invention shall mean the average particle diameter calculated | required with the apparatus, after measuring the particle size distribution of a porous inorganic filler by SALD series which is a particle size distribution meter made from Shimadzu Corporation. More specifically, the particle size range of the obtained particle size distribution is divided into n (maximum particle size: x ₁ , minimum particle size: x _{n + 1} ), and each particle size interval [x _j , x _{j + 1} ] Based on the logarithmic scale.

Furthermore, assuming that q _j is the relative particle amount (difference%) corresponding to the particle diameter interval [x _j , x _{j + 1} ] and the total of all the intervals is 100%, the average value μ on the logarithmic scale is Is required.

Since the average value μ is a numerical value on a logarithmic scale, the average particle diameter is calculated as 10 ^μ .

  As the inorganic filler used in the method of the present invention, a porous filler is suitable. Unlike inorganic fillers that do not have pores on the surface, if they are porous inorganic fillers, the surface modifier penetrates into the pores in the surface modification step, and the liquid crystal polymer molecules extend from the pores in the polymerization step. . As a result, the bonding strength between the inorganic filler and the liquid crystal polymer molecules is increased, and the strength of the liquid crystal polymer composition may be further increased. In addition, not only when the polymer is chemically bonded to the pore inner surface, but the monomer that has penetrated into the pore space is polymerized to grow the liquid crystal polymer molecular chain, and apparently the structure in which the liquid crystal polymer enters the pore. I can take it. In such a physical “fitting” state, since the so-called anchor effect is exhibited, it can be expected that the strength of the liquid crystal polymer composition is further increased.

  On the other hand, by mixing a porous inorganic filler having a sufficiently large pore size with a thermotropic liquid crystal polymer in a molten state or a rheotropic liquid crystal polymer in a solution state, the polymer penetrates into the pores and has an anchor effect. It is not impossible to think that it will be demonstrated. However, in reality, when a linear polymer such as a liquid crystal polymer approaches the pores of the filler in an environment where it is mixed with the porous inorganic filler, as a single molecular chain, the direction in which the cross-sectional area is minimized, that is, The possibility that the straight chain approaches in the direction of entering the hole from its tip is extremely low. Therefore, it can be said that the possibility that liquid crystal polymer molecules enter the pores by simple mixing is low. If the pore size is as large as several tens of μm to sub millimeters, it may enter the pores as a polymer mass having a volume in which molecular chains are aggregated, and exert an anchor effect. However, in that case, the filler size becomes enormous and the homogeneity of the material is impaired, and the strength of the filler itself is also extremely lowered.

In order to exhibit the above effect more effectively, the ratio of the pores having a diameter of 2 to 100 nm in all the pores is 80% or more, or the pore volume of the diameter of 2 to 100 nm is 0.002 cm ³ / g or more. Is preferred. The molecular size of the monomer that is the raw material of the liquid crystal polymer is about 1 nm, and the molecular size of the active site of the silane coupling agent that is preferably used as the surface modifier is about 1 nm. Therefore, the effect described above can be expected if the hole has a diameter of 2 nm or more. On the other hand, if the pore diameter is too large, the strength of the porous inorganic filler may be lowered. Therefore, the pore diameter is preferably 100 nm or less. In addition, when the volume of the pores having an appropriate diameter is 0.002 cm ³ / g or more, the effect of improving the bonding force between the liquid crystal polymer molecules and the porous inorganic filler can be sufficiently exerted.

The pore diameter and pore distribution, and the specific surface area and pore volume in the porous inorganic filler can be measured by a gas adsorption method or a press-fitting method such as Hg. In the present invention, based on the pore distribution obtained by the nitrogen gas adsorption method, the ratio of the pores having a diameter of 2 to 100 nm in the graph representing the pore distribution is 80% or more, or the pore volume having a diameter of 2 to 100 nm is 0.00%. A porous inorganic filler that is 002 cm ³ / g or more is preferably used.

  In the method of the present invention, a functional group having a binding ability with a monomer constituting the liquid crystal polymer molecule is introduced on the surface of the porous inorganic filler. More specifically, the surface of the porous inorganic filler is modified by a compound having an affinity for the porous inorganic filler and having a functional group capable of binding to the monomer constituting the liquid crystal polymer molecule. To do. Here, since the monomer of the liquid crystal polymer has a reactive group such as a hydroxyl group, a carboxyl group, and an amino group, the functional group having a binding ability with the monomer includes a carboxyl group, an isocyanate group, an amino group, and an acid anhydride group. , Hydroxyl group, glycidyl group, ester group, trialkoxysilyl group and the like.

Therefore, as a modifier for the surface of the porous inorganic filler, a silane coupling agent such as trimethoxysilane or triethoxysilane having the above functional group; a titanium system such as trimethoxy titanium or triethoxy titanium having the above functional group Coupling agents; reactive crosslinking agents such as triallyl cyanurate and trimethallyl cyanurate; acid anhydrides such as trimellitic acid anhydride and pyromellitic acid anhydride. Further, a temperature at which the monomer constituting the liquid crystal polymer molecule is dissolved, and those having a boiling point of about 150 ° C. or higher are suitable, for example, γ-aminopropyltriethoxysilane or γ-glycidoxypropyltrimethoxysilane. Etc. can be used. In addition, cyanurate compounds such as triallyl cyanurate and trimethallyl cyanurate; acid anhydrides such as trimellitic acid anhydride and pyromellitic acid anhydride; and moreover, those having a hydrolyzable silyl group typified by alkoxysilane A mixture or a partial condensate of the compound and an alkoxysilane represented by the general formula of R ¹ _x -Si (OR ² ) _4-x can be given.

  Of the compound group including a mixture of a polymer having a hydrolyzable silyl group and an alkoxysilane or a partial condensate, in the present invention, fluorine-containing compounds are included from the viewpoint of heat resistance and chemical resistance. It is advantageous. Further, in order to improve the affinity between the filler and the liquid crystal polymer, the fluorine-containing copolymer contains a plurality of hydrolyzable silyl groups, or at least one hydrolyzable silyl group, and also at least one liquid crystal Those having both a polymer raw material monomer and a reactive functional group are preferred.

  For the modification treatment of the surface of the porous inorganic filler, a general reaction according to the kind of the porous inorganic filler or the surface modifier may be applied. For example, when using a silane-based or titanium-based coupling agent, the coupling agent is diluted with water, methanol, ethanol or a mixed solvent thereof, or further hydrolyzed by adding an acid such as acetic acid. Then, the porous inorganic filler is impregnated. In order to distribute the modifier into the pores of the porous inorganic filler, the modification treatment may be performed in a reduced pressure state. Further, it may be heated to room temperature to 150 ° C. according to a known method, and the reaction may be carried out for about 0.5 to 1 hour.

  Next, the porous inorganic filler is separated from the solvent and the surface modifier by filtration or the like and dried. At this time, the drying may be performed under heating or under reduced pressure, and a spray drying method or a fluidized bed drying method may be used to prevent secondary aggregation of the porous inorganic filler. However, if the surface modifier is not present in a large excess and there is no possibility that the independent surface modifier will react with the monomer so that the main reaction is inhibited in the subsequent steps, the drying is not performed. You may proceed to the next process as it is. In this case, secondary aggregation of the porous inorganic filler hardly occurs.

  Further, one of monomers constituting the target liquid crystal polymer molecule may be further bonded to the functional group introduced on the surface of the obtained porous inorganic filler. For example, in the presence of a solvent or a catalyst, the surface-modified inorganic filler obtained above and one of the monomers are mixed and reacted at about 100 to 300 ° C. for 0.5 to 5 hours to bond the monomers. After completion of the reaction, the silica may be separated and dried as described above, or the reaction mixture may be used as it is in the next step without separation.

(2) Mixing step Next, the porous inorganic filler into which the functional group is introduced and the monomer constituting the liquid crystal polymer molecule are mixed. As the monomer here, one according to the liquid crystal polymer which is the target is used.

  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 of the liquid crystal polymers of the composition according to the present invention may be used. However, when the composition is extruded, a thermotropic liquid crystal polymer is suitable, and more specifically, the thermotropic liquid crystal polyester or thermotropic liquid is used. Liquid crystalline polyester amide is preferred.

  Thermotropic liquid crystal polyester (hereinafter simply referred to as “liquid crystal polyester”) is, for example, an aromatic polyester synthesized mainly from aromatic dicarboxylic acid and monomers such as aromatic diol and aromatic hydroxycarboxylic acid. Sometimes it exhibits liquid crystallinity. 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.

  Examples of the liquid crystal polymer according to the present invention include units represented by the above formulas (1) to (3), as long as they exhibit liquid crystallinity (particularly thermotropic liquid crystallinity) and can achieve the object of the present invention. It may be a copolymer type polymer (for example, 50 mol% or more in all constituent units of the liquid crystal polymer) and also having other units. Examples of the other unit include a unit having an ether bond, a unit having an imide bond, and a unit having an amide bond.

  Moreover, as liquid crystal polyester amide, the said liquid crystal polyester which has an amide bond as another unit corresponds, for example, what has a structure of the following Formula (4) is mentioned. For example, in the formula (4), the molar ratio of the unit of s, the unit of t, and the unit of u is 70/15/15.

  The liquid crystal polymer used in the present invention may contain a polymer other than the liquid crystal polymer as long as characteristics such as dielectric properties are not excessively given up. The polymer may be simply mixed with the liquid crystal polymer or may be chemically bonded. Examples of such an alloy polymer include, but are not limited to, polyetheretherketone, polyethersulfone, polyimide, polyetherimide, polyamide, polyamideimide, polyarylate, and the like. The mixing ratio of the liquid crystal polymer and the alloy polymer is not particularly limited. For example, the mass ratio is preferably 50:50 to 95: 5, and more preferably 70:30 to 90:10. A polymer alloy containing a liquid crystal polymer can also have excellent characteristics due to the liquid crystal polymer.

  In the present invention, a monomer corresponding to the target liquid crystal polymer is used. For example, when the liquid crystal polymer shown above is desired, an aromatic dicarboxylic acid, an aromatic dihydroxy compound, an aromatic hydroxycarboxylic acid or the like constituting each unit is used. Further, the hydroxyl group, amino group, and carboxyl group of the monomer may be activated in advance. For example, hydroxyl groups can be activated by acyl groups such as acetyl groups. In addition, each monomer may have a general substituent such as a halogen such as a fluorine atom or a chlorine atom, or may have an appropriate side chain such as a halogenated alkyl group.

  What is necessary is just to select a suitable mixing method mainly with the state of a porous inorganic filler and a monomer. For example, when the porous inorganic filler and the monomer are both in a solid state, they may be heat-melted after dry blending without a solvent. However, in this method, since the localization of the material may occur, a dispersion medium is preferably used. The dispersion medium used here is not particularly limited as long as it can appropriately dissolve or disperse monomers and the like, and for example, N-methylpyrrolidone, acetic anhydride, acetic acid and the like can be used. In particular, acetic anhydride or acetic acid is preferred because it has a relatively low boiling point and can be easily distilled off, can suppress coloring of the liquid crystal polymer composition to be obtained, and further has an activating effect on the functional group of the monomer. In the case where the porous inorganic filler is not separated and dried in the previous surface modification step, the reaction solution and the monomer in the surface modification step may be mixed in the presence of the dispersion medium.

  The mixing ratio of the porous inorganic filler and the monomer is not particularly limited. For example, the porous inorganic filler can be 1 to 300 parts by mass, more preferably 1 to 200 parts by mass, and still more preferably 100 parts by mass of the monomer. Can be 2 to 100 parts by mass. In addition, when emphasizing the fluidity at the time of subsequent molding processing, the weight part of the porous inorganic filler with respect to 100 parts by mass of the monomer is preferably 2 to 20 parts by weight, on the other hand, by adding the porous inorganic filler When emphasizing the CTE reduction effect, the weight part of the porous inorganic filler is preferably 20 to 100 parts by weight with respect to 100 parts by weight of the liquid crystal polymer.

  When the porous inorganic filler and the monomer are mixed, they are often in a simple mixed state at room temperature, but preferably the suspension is gradually heated while stirring to make it as uniform as possible. In addition, it is also conceivable that a part of the functional group on the surface of the porous inorganic filler is bonded to the monomer by mixing the surface-modified porous inorganic filler and the monomer.

(3) Polymerization step Next, the obtained mixture is subjected to a polymerization reaction. In this process, the monomer is polymerized to form a liquid crystal polymer, part of which is porous through the functional group introduced to the surface of the porous inorganic filler by the surface modification process and further through the monomer bonded to the functional group. Bonds to the surface of the inorganic filler.

  General conditions may be adopted as the conditions for the polymerization reaction. For example, the mixture of the porous inorganic filler and monomer obtained in the previous step is introduced into a reaction vessel, and the inside of the reaction vessel is replaced with an inert gas such as nitrogen gas or argon gas to advance the reaction. At this time, the reaction may be performed in the presence of a polymerization catalyst. As the polymerization catalyst, acetates of metals such as magnesium, tin, lead, sodium and potassium, heterocyclic organic compounds such as N, N-dimethylaminopyridine, and the like can be used. The temperature and reaction time during the reaction may be appropriately selected and are not particularly limited. For example, the reaction is carried out at about 150 to 350 ° C. for about 0.5 to 5 hours while distilling off low-boiling byproducts such as water and acetic acid. Just do it. In addition, the reaction temperature at this time may be divided into multiple stages, and the temperature gradient until reaching each temperature may be set individually.

  In the polymerization reaction of the liquid crystal polymer, the viscosity of the reaction mixture increases rapidly, and it may be difficult to take out the polymer from the reaction vessel. In such a case, the reaction mixture is taken out from the reaction vessel before the viscosity becomes excessively high, transferred to another reaction vessel, the inside of the reaction vessel is replaced with an inert gas, or heated under reduced pressure conditions. You may employ | adopt what is called a solid-state polymerization process which advances reaction further by this.

(4) Molding step The liquid crystal polymer composition obtained by the method of the present invention can be used for various applications by molding by a more general method. For example, it can take the shape of a film, a sheet, a fiber, a nonwoven fabric, a three-dimensional molded product, and the like.

Conventionally, anisotropy control in a plane parallel to the molding direction has been performed by stretching or the like. However, in the case of a film or sheet, the stretching process is usually performed only in the direction orthogonal to the extrusion direction in the plane of the film sheet, that is, in the width direction of the film or sheet. It was oriented only in the plane direction of the sheet. That is, the effect of controlling the CTE low by molecular orientation was an effect that can be expected only in the plane of the film or sheet. On the other hand, since it is virtually impossible to perform processing such as stretching in the thickness direction of a film or sheet, liquid crystal polymer molecules are hardly aligned in the thickness direction by stretching, and by molecular orientation by molding The CTE (CTE _z ) in the thickness direction could not be reduced.

On the other hand, in the composition of the present invention, the CTE _VOL as the liquid crystal polymer composition material is reduced by the addition of the porous inorganic filler, so that the component CTE _z can be substantially reduced. In addition, a part of the liquid crystal polymer molecules bonded to the surface of the porous inorganic filler in an arbitrary direction is oriented in the thickness direction, thereby disturbing the orientation of the surrounding liquid crystal polymer molecules in the thickness direction. By further adding molecular orientation components to CTE _z , the CTE _z is further reduced. In addition, since the affinity between the porous inorganic filler and the liquid crystal polymer matrix is enhanced, the aggregation of the porous inorganic filler and the resulting decrease in strength are also suppressed.

  Therefore, the liquid crystal polymer composition of the present invention can be used particularly effectively as an insulator material for electronic circuit boards that have recently been required to have higher precision and multilayering.

  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. It is also possible to implement, and they are all included in the technical scope of the present invention.

  First, the particle size and pore distribution of the inorganic filler used in the following examples were measured. Specifically, the particle size was measured by a laser diffraction method using a particle size distribution measuring device (manufactured by Shimadzu Corporation, trade name “SALD-2000J”). The pore distribution was measured at an analysis radius range of 0.85 to 150 nm by a nitrogen gas adsorption method using a pore distribution measuring device (manufactured by Shimadzu Corporation, trade name “ASAP2010”). The results are shown in Table 1. Moreover, the differential pore volume distribution of the filler A in Table 1 is shown in FIG. 1, the differential pore volume distribution of the filler D is shown in FIG. 2, and the differential pore volume distribution of the filler C is shown in FIG.

Example 1
(1) Surface modification of inorganic filler Filler A (porous silica, 20 g) in Table 1 was placed in a glass container (500 mL) equipped with a stirrer and a reflux condenser, and γ-aminopropyltrimethoxysilane (8 g, A 5 wt% solution prepared by dissolving Shin-Etsu Chemical Co., Ltd., trade name "KBM-903") in ultrapure water (152 g) was added dropwise. Next, after irradiating ultrasonic waves for 5 minutes, the temperature was raised to 110 ° C. in an oil bath, and the mixture was heated to reflux for 1.5 hours. After completion of the reaction, the inorganic filler was filtered through a suction filter, washed with acetone, and then dried under reduced pressure at 100 ° C. for 2 hours and then at 150 ° C. overnight in the atmosphere.

  Furthermore, the said inorganic filler (20g), isophthalic acid (4.0g), and N-methylpyrrolidone (200mL) were put into the glass container (500mL) provided with the stirring apparatus and the reflux condenser, and it was set as suspension. The reaction solution was heated to 230-240 ° C. in an oil bath and heated to reflux for 2 hours. After completion of the reaction, the inorganic filler was filtered through a suction filter, washed with acetone, and then dried under reduced pressure at 100 ° C. for 2 hours and then at 150 ° C. overnight in the atmosphere.

(2) Mixing of surface modified inorganic filler and monomer Acetic acid (20 mL) was placed in a vessel (500 mL) equipped with a stirrer, torque meter, nitrogen gas inlet tube, thermometer and reflux condenser, The obtained surface-modified inorganic filler (11.9 g) was suspended, and 4-acetoxybenzoic acid (54 g, 300 mmol), 4,4′-diacetoxybiphenyl (32.4 g, 120 mmol), terephthalic acid (12 0.5 g, 75 mmol), and isophthalic acid (7.5 g, 45 mmol) were added. After replacing the inside of the reaction vessel with nitrogen gas, the temperature was raised to 150 ° C. over 20 minutes while gently stirring under a nitrogen gas stream (200 mL / min). At this time, when the reaction liquid temperature reached 100 ° C., the mixed liquid of the inorganic filler and the monomer was in a completely uniform state. After the reaction solution temperature reached 150 ° C., the mixture was further stirred for 10 minutes.

(3) Polymerization reaction Following the above (2), stirring of the mixed liquid of the inorganic filler and the monomer is continued under a nitrogen gas stream (200 mL / min), and the temperature is raised to 320 ° C. over 2 hours while acetic acid is distilled off. The mixture was further stirred at 320 ° C. for 1 hour to proceed the polymerization reaction. In this process, polymerization of the reaction product progressed, and after the viscosity of the reaction product increased, the pressure was reduced over 10 minutes, and the reaction was further performed for 30 minutes. The obtained polymer was pulverized and dried at 150 ° C. for 8 hours.

(4) Solid-phase polymerization reaction The polymer (about 30 g) of (3) above was placed in a solid-phase polymerization vessel (200 mL) equipped with a nitrogen gas introduction tube, and the inside of the vessel was replaced with nitrogen gas. (200 mL / min) The temperature was raised to 250 ° C. over 1 hour and held at 250 ° C. for 3 hours. Subsequently, it was allowed to cool to room temperature under a nitrogen gas stream to obtain a liquid crystal polymer composition.

Example 2
A liquid crystal polymer composition was obtained in the same manner as in Example 1 except that filler C (porous silica, 20 g) was used instead of filler A in Table 1.

Comparative Example 1
In step (2) of Example 1 above, the monomers were mixed without adding the surface-modified inorganic filler obtained in step (1), and then the polymerization reaction in step (3) was performed. In step (3), the monomer mixture is held at 320 ° C. for 1 hour, and after confirming that the polymerization has progressed and the viscosity of the reaction product has increased, the surface is modified in the same manner as in step (1). Inorganic filler A was mixed. Next, a liquid crystal polymer composition was obtained through the solid phase polymerization reaction in step (4).

Comparative Example 2
A liquid crystal polymer composition was obtained in the same manner as in Example 1 except that the filler A that was not subjected to surface modification in the step (1) was used.

Comparative Example 3
A liquid crystal polymer composition was obtained in the same manner as in Comparative Example 1 except that the filler A that was not subjected to surface modification in the step (1) was used.

Comparative Example 4
A liquid crystal polymer composition was obtained in the same manner as in Example 1 except that filler D (nonporous silica) was used.

Comparative Example 5
A liquid crystal polymer composition was obtained in the same manner as in Comparative Example 2 except that filler D (nonporous silica) was used.

Comparative Example 6
A liquid crystal polymer composition was obtained by carrying out steps (2) to (4) of Example 1 without using an inorganic filler.

Comparative Example 7
In step (2) of Example 2 above, the monomers were mixed without adding the surface-modified inorganic filler obtained in step (1), and then the polymerization reaction in step (3) was performed. In step (3), the monomer mixture is held at 320 ° C. for 1 hour, and after confirming that the polymerization has progressed and the viscosity of the reaction product has increased, the surface is modified in the same manner as in step (1). Inorganic filler C was mixed. Next, a liquid crystal polymer composition was obtained through the solid phase polymerization reaction in step (4).

Comparative Example 8
A liquid crystal polymer composition was obtained in the same manner as in Example 2 except that the filler C that was not subjected to surface modification in the step (1) was used.

Comparative Example 9
A liquid crystal polymer composition was obtained in the same manner as in Comparative Example 7 except that the filler C that was not subjected to surface modification in the step (1) was used.

Test Example 1 Evaluation of coefficient of thermal expansion (CTE) The fluidity of the obtained liquid crystal polymer composition was measured according to JIS K7210. Specifically, in a flow tester (manufactured by Shimadzu Corporation, trade name “CFT500”), the die diameter φ is set to 1 mm, the die length is set to 10 mm, the load is set to 20 kgf, and the liquid crystal polymer composition is set in the cylinder. After holding at 180 ° C. for 180 seconds, the temperature was increased at a rate of temperature increase of 4 ° C./min, and the temperature at which kinematic viscosity was 10,000 P was determined.

Subsequently, the CTE of the liquid crystal polymer composition was measured according to JIS K7197. First, the liquid crystal polymer composition was formed into a 10 cm long × 10 cm wide × 100 μm thick film and a 10 cm long × 10 cm wide × 400 μm thick sheet using a vacuum heating press. The temperature at this time was 20 ° C. higher than the temperature at which the kinematic viscosity obtained above was 10,000 P. The obtained film was cut into small pieces having a width of 5 mm and a length of 25 mm, the sheet was cut into small pieces having a length of 10 mm and a width of 10 mm, set in a TMA analyzer (trade name “TMA-100” manufactured by Seiko Instruments Inc.), and heated. Temperature: CTE _x , CTE _y and CTE _z are measured in the range of 50-100 ° C., 100-150 ° C., and 150-200 ° C. in the temperature drop region after heating from 35 ° C. to 260 ° C. at 10 ° C./min. did. Here, normally, the sheet is manufactured by extrusion molding, and its CTE is measured in the extrusion direction and the direction orthogonal thereto. In the above, a film having a thickness of 100 μm is manufactured by compression molding, and any one direction in the plane direction The CTE in the other direction perpendicular to it was measured in the tensile mode, and this was appropriately set as CTE _x and CTE _y, and the in-plane CTE (CTE _xy ) was determined by the following equation.
In-plane CTE: CTE _xy = 1/2 (CTE _x + CTE _y )

In addition, the CTE in the thickness direction of a separately manufactured sheet having a thickness of 400 μm was measured in the compression mode to obtain the thickness direction CTE (CTE _z ). Furthermore, the volume expansion coefficient (CTE _vol ) was determined by the following formula. The results are shown in Table 2.
CTE _vol = 2 x CTE _xy + CTE _z

Test Example 2 Evaluation of Mechanical Strength The mechanical strength of the liquid crystal polymer composition was measured according to JIS K7127. Specifically, the sheet obtained in the same manner as in Test Example 1 was cut into a test piece type 5 shape, set in a tensile tester (trade name “TENSIRON RTC-1210A” manufactured by ORIENTEC), and tensile speed: 50 mm / The maximum point stress at the time of pulling in minutes and breaking was determined. The results are shown in Table 2.

Test Example 3 Evaluation of Inorganic Filler Dispersibility The surface of the sheet obtained in the same manner as in Test Example 1 was measured at a magnification of 1,000 times with a scanning electron microscope (trade name “S-3500N” manufactured by Hitachi, Ltd.). The number of aggregates having a diameter of 5 μm or more contained in a 126 μm × 85 μm region of the obtained surface image was determined. The results are shown in Table 2. In Table 2, “-” indicates that no measurement was performed.

  As shown in Table 2, when the mechanical strength is compared by the maximum point stress, the strength of the liquid crystal polymer compositions of Comparative Examples 2 to 5 is lower than the composition of Comparative Example 6 to which no inorganic filler is added. The cause is that the inorganic filler aggregates because the affinity between the liquid crystal polymer matrix, which is an organic compound, and the inorganic filler is low, and the properties of the inorganic filler added to increase the strength are not effectively exhibited. It is believed that there is.

  On the other hand, the composition of Comparative Example 1 in which a porous inorganic filler having a large surface area was surface-modified with a silane coupling agent was improved in the affinity between the liquid crystal polymer matrix and the inorganic filler. The strength is higher than that of the composition of Comparative Example 6 that is not. However, the effect is not always sufficient.

  On the other hand, the composition of Example 1 polymerized after using the surface-modified porous filler and mixing the filler and the monomer in advance has sufficient mechanical strength. The reason for this is that the liquid crystal polymer molecules bonded to the surface of the inorganic filler have significantly improved the affinity with the liquid crystal polymer matrix, and the liquid crystal polymer molecules enter the pores of an appropriate diameter, thus exhibiting an anchor effect. It is thought to be due to.

  Further, in the composition of Example 1 that undergoes a step of uniformly mixing the surface-modified porous inorganic filler and the raw material monomer of the liquid crystal polymer in the presence of the dispersion medium, the number of aggregates is reduced, Material uniformity is significantly improved. Even in the case where the inorganic filler is not subjected to the surface modification treatment or in the composition of Comparative Example 2 which has undergone such a mixing step, the number of aggregates is relatively small.

  On the other hand, the composition of Comparative Example 1 and Comparative Example 3 in which the liquid crystal polymer and the inorganic filler are mixed after the polymerization reaction has a large number of agglomerates regardless of the presence or absence of the surface modification treatment of the inorganic filler.

  As mentioned above, it turns out that the process of mixing an inorganic filler and a monomer before a polymerization process is important for reduction of an aggregate.

  Next, the CTE reduction effect will be considered.

Conventionally, it is known that the CTE _vol of a liquid crystal polymer composition is reduced by adding an inorganic filler having a CTE smaller than that of the liquid crystal polymer. However, according to the results of Comparative Example 6 with no inorganic filler added, and Comparative Example 2 polymerized after mixing the porous inorganic filler not subjected to the surface modification treatment and the monomer, 100 to 150 ° C. and 150 to 150 ° C. Although the reduction of CTE _vol is observed in the region of 200 ° C., the CTE _vol reduction effect due to the addition of filler is not seen in the region of 50 to 100 ° C. In Comparative Example 8 except that filler C was used instead of filler A, a decrease in CTE _vol was observed in the region of 100 to 150 ° C., but CTE _{vol in} the regions of 50 to 100 ° C. and 150 to 200 ° C. There is no reduction effect.

On the other hand, in the compositions of Example 1 and Example 2 polymerized after mixing the surface-modified porous inorganic filler and the monomer, the entire temperature range of 50 to 100 ° C., 100 to 150 ° C. and 150 to 200 ° C. As compared with Comparative Example 6, a significant reduction in CTE _vol was observed.

As described above, in order to obtain a liquid crystal polymer composition having high mechanical strength and uniformity and reduced CTE _vol (volume expansion coefficient),
(1) Using a porous inorganic filler,
(2) The surface of the inorganic filler is modified so that its surface exhibits reactivity with the monomer that is the raw material of the liquid crystal polymer,
(3) It has been demonstrated that it is important to polymerize after the surface-modified inorganic filler is mixed with the monomer in advance.

It is a figure which shows the differential pore volume distribution of the filler A in Table 1. It is a figure which shows the differential pore volume distribution of the filler D in Table 1. It is a figure which shows the differential pore volume distribution of the filler C in Table 1.

Claims (5)

A method for producing a liquid crystal polymer composition comprising:
A step of introducing a functional group having a binding ability with a monomer constituting a liquid crystal polymer molecule on the surface of the porous inorganic filler; and a porous inorganic filler into which the functional group is introduced and a monomer constituting the liquid crystal polymer molecule Mixing and subjecting the resulting mixture to a polymerization reaction;
A method for producing a liquid crystal polymer composition, comprising:   The method for producing a liquid crystal polymer composition according to claim 1, wherein in the porous inorganic filler, a ratio of pores having a diameter of 2 to 100 nm occupying all pores is 80% or more. ^{3. The} method for producing a liquid crystal polymer composition according to claim 1, wherein the porous inorganic filler has a pore volume of 2 to 100 nm in diameter of 0.002 cm ³ / g or more.   The method for producing a liquid crystal polymer composition according to any one of claims 1 to 3, wherein mixing of the porous inorganic filler into which the functional group is introduced and the monomer constituting the liquid crystal polymer molecule is performed in the presence of acetic anhydride or acetic acid. .   The material of the porous inorganic filler is one or more selected from the group consisting of silica, alumina, alumina silica, zeolite, glass, aluminum nitride, calcium carbonate, shirasu, and diatomaceous earth. A method for producing a liquid crystal polymer composition.

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