JP2010095669A - Liquid crystalline polymer composition and molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystalline polymer composition producing a molded article having high-degree electromagnetic wave shielding effect and electric insulating property, and to provide a molded article obtained by using the liquid crystalline polymer composition. <P>SOLUTION: The liquid crystalline polymer composition includes a component (A) which is a liquid crystalline polymer and a component (B) which is a composite material composed of a ceramic powder containing silicon oxide as a main component and a soft magnetic metal powder, wherein the weight content of the component (B) is equal to or higher than that of the component (A). It is preferable that the component (B) is a composite material formed from iron or an iron alloy and silica. Such a liquid crystalline polymer composition can be made into a composition in the form of pellets by melting and kneading. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal polymer composition having excellent electromagnetic shielding properties and electrical insulation properties, and a molded body using the composition.

  In recent years, with the explosive spread of mobile phones and the enhancement of the performance of OA devices such as personal computers, the operating frequency of such electronic devices has been increased. On the other hand, an electronic device that operates at such a high operating frequency has a problem that high-frequency electromagnetic waves are radiated from electronic components such as a processor and a communication cable in the electronic device, and the electronic device malfunctions due to the electromagnetic waves. There is. In addition, such electromagnetic waves cause malfunctions to other electronic devices in the vicinity, and there are concerns about the influence on the human body, and countermeasures against the electromagnetic waves have become indispensable.

  Conventionally, as a countermeasure against electromagnetic waves, an electromagnetic wave shielding method that suppresses the emission of electromagnetic waves by using a metal case or the like as an electromagnetic wave shielding member and covering the electronic components has been taken. However, such a metal case is difficult to reduce in size or weight, and cannot meet the demands for downsizing and portability of electronic devices. As an electromagnetic shielding material that solves this problem, Patent Document 1 proposes a composition in which a soft magnetic metal flat powder having iron as a base metal having a specific bulk density / true density ratio is blended in a resin binder, and such a composition. It is disclosed that a molded body using a product is useful as an electromagnetic wave absorber / interferer. Patent Document 2 proposes an electromagnetic wave shielding material in which a soft magnetic powder subjected to a coupling treatment is mixed into a liquid crystal polymer or polyphenylene sulfide.

JP 2003-209010 A (Claims) Japanese Patent Laid-Open No. 2001-237591 (Claims)

However, since the composition proposed in Patent Document 1 uses conductive iron powder, it is necessary to provide an electronic component (for example, an internal element of an electronic device) that requires insulation as in the case of the metal case. It is not suitable as an electromagnetic shielding member against terminals). Further, even in the electromagnetic wave shielding material proposed in Patent Document 2, it is difficult to suppress the conductivity generated by the soft magnetic powder, and the electrical insulation is insufficient.
Thus, while using a resin material having excellent lightness, an electromagnetic wave shielding material having a formability (working) property capable of forming a small part instead of a conventional electromagnetic wave shielding member and having an excellent electrical insulation property. It was sought after.
Accordingly, an object of the present invention is to provide a liquid crystal polymer composition capable of producing a molded article having a high electromagnetic shielding effect and electrical insulation, and in particular, a liquid crystal polymer composition that can be expected to have moldability and light weight. It is to provide.

  As a result of intensive studies to solve the above problems, the present inventors have completed the present invention.

That is, the present invention provides the following <1> liquid crystal polymer composition.
<1> Liquid crystal polymer composition (A) Liquid crystal polymer (B) comprising the following component (A) and component (B), wherein the content of component (B) is equal to or greater than the content of component (A) ) Composite material of ceramic powder containing silicon oxide as main component and soft magnetic metal powder

（式中、Ａｒ₁は、１，４−フェニレン基、２,６−ナフタレンジイル基又は４，４’−ビフェニリレン基を表す。Ａｒ₂及びＡｒ₃はそれぞれ独立に、１，４−フェニレン基、２,６−ナフタレンジイル基、１，３−フェニレン基又は４，４’−ビフェニリレン基を表す。また、Ａｒ₁、Ａｒ₂及びＡｒ₃は、その芳香環上の水素原子の一部又は全部が、ハロゲン原子、アルキル基、アリール基に置換されていてもよい。）
＜７＞前記成分（Ａ）が、前記（Ａ３）の液晶ポリエステルを含む、＜６＞の液晶ポリマー組成物；
＜８＞スクリューの有効長さ（Ｌ）のスクリュー直径（Ｄ）に対する比率（Ｌ／Ｄ）が２０以上（ＬとＤは同一のスケール単位である）の溶融混練押出機を用い、前記溶融混練押出機の押出方向上流部に設けられた上流部供給口から、前記成分（Ａ）を、その全供給量に対する９０重量％以上が供給されるように、前記成分（Ｂ）を、その全供給量の５０重量％以下が供給されるように、前記溶融混練押出機に供給し、前記上流部供給口よりも押出方向下流側に設けられた下流側供給口から、前記成分（Ａ）の残部と前記成分（Ｂ）の残部とを前記溶融混練押出機に供給することにより、前記成分（Ａ）と前記成分（Ｂ）とを溶融混練して得られる、＜１＞〜＜７＞のいずれかの液晶ポリマー組成物 Furthermore, the present invention provides the following <2> to <8> as preferred embodiments according to the above <1>.
<2> The liquid crystal polymer composition according to <1>, comprising 100 to 450 parts by weight of the component (B) with respect to 100 parts by weight of the component (A);
<3> The liquid crystal polymer composition according to <1> or <2>, wherein the component (B) is a composite material obtained by coating the soft magnetic metal powder with the insulating ceramic powder;
<4> The liquid crystal polymer composition according to any one of <1> to <3>, wherein the soft magnetic metal powder constituting the component (B) is a soft magnetic metal powder made of iron or an iron alloy;
<5> The liquid crystal polymer composition according to any one of <1> to <3>, wherein the soft magnetic metal powder constituting the component (B) is made of iron or an iron alloy and has a flatness ratio of 2 or more;
<6> The liquid crystal according to any one of <1> to <5>, wherein the component (A) is at least one liquid crystal polyester selected from the group consisting of the following (A1), (A2), and (A3): A polymer composition;
(A1) Liquid crystalline polyester composed of repeating units represented by (i) below (A2) Liquid crystalline polyester composed of repeating units represented by (ii) below and (iii) (A3) Liquid crystalline polyester comprising repeating units represented by i), (ii) and (iii)

(In the formula, Ar ₁ represents a 1,4-phenylene group, a 2,6-naphthalenediyl group, or a 4,4′-biphenylylene group. Ar ₂ and Ar ₃ are each independently a 1,4-phenylene group, 2,6-naphthalenediyl group, 1,3-phenylene group or 4,4′-biphenylylene group, and Ar ₁ , Ar _2, and Ar ₃ are all or part of hydrogen atoms on the aromatic ring. , May be substituted with a halogen atom, an alkyl group, or an aryl group.)
<7> The liquid crystal polymer composition of <6>, wherein the component (A) comprises the liquid crystal polyester of (A3);
<8> A melt kneading extruder having a ratio (L / D) of the effective length (L) of the screw to the screw diameter (D) of 20 or more (L and D are the same scale unit) is used. The component (B) is fully fed so that 90% by weight or more of the component (A) is fed from the upstream feed port provided in the upstream portion of the extruder in the extrusion direction. The remaining amount of the component (A) is supplied to the melt-kneading extruder so that 50% by weight or less of the amount is supplied, and from the downstream supply port provided on the downstream side in the extrusion direction from the upstream supply port. Any of <1> to <7>, obtained by melt-kneading the component (A) and the component (B) by supplying the remaining component and the remainder of the component (B) to the melt-kneading extruder Liquid crystal polymer composition

In addition, the present invention provides the following <9> to <10> using any one of the liquid crystal polymer compositions.
<9> A molded product obtained by molding the liquid crystal polymer composition according to any one of <1> to <8>;
<10> Molded body of <9> used as a surface mount component

  Since the liquid crystal polymer composition of the present invention is excellent in moldability, small parts and the like can be easily obtained. In addition, a molded product obtained by molding the liquid crystal polymer composition is excellent in electromagnetic shielding properties and electrical insulation properties, and is extremely useful for electromagnetic shielding members for electronic devices, particularly surface mount electronic components. The utility value of is great.

  Hereinafter, regarding preferred embodiments of the present invention, a component (B) composite material, a component (A) liquid crystal polymer, a liquid crystal polymer composition comprising the component (A) and the component (B), a method for producing the same, and the liquid crystal The molded body using the polymer composition will be sequentially described.

<(B) Composite material>
First, the component (B) composite material (hereinafter sometimes referred to as “composite material (B)”) will be described.
The composite material (B) used in the present invention is a composite material (composite) mainly composed of ceramic powder containing silicon oxide and soft magnetic metal powder. In particular, those having a volume average particle size called nanocomposite (hereinafter sometimes referred to as “average particle size”) of about 1 to 100 μm are preferable. In the method for producing a liquid crystal polymer composition described later, the component (A) liquid crystal polymer On the other hand, from the viewpoint of developing good dispersibility, the average particle size is preferably 10 to 50 μm. Here, the soft magnetic metal is a metal material having a small coercive force and a large magnetic permeability. The permeability of the soft magnetic metal of the composite material (B) used in the present invention is preferably 100 or more, more preferably 200 or more, expressed by the relative permeability divided by the vacuum permeability.

  Here, soft magnetic metals having a relative magnetic permeability of 100 or more are described in terms of the relative magnetic permeability based on, for example, the chronological table (published by Riko Books) and Noriyuki Namba and Fumitaka Kaneko “Electrical Materials—Dielectric Materials / Magnetic Materials—” on page 208. One hundred or more soft magnetic metals can also be selected. Preferred examples include cobalt, iron, and nickel, and particularly preferred is iron or nickel. In addition, the soft magnetic metal of the present invention is a concept including an alloy containing a soft magnetic metal. Specific examples of the alloy include an Fe—Si alloy (silicon steel), an Fe—Al alloy ( Alpalm), Fe-Ni alloy (permalloy), Fe-Co alloy, Fe-V alloy (permendur), Fe-Cr alloy, Fe-Si alloy (silicon steel), Fe-Al-Si Alloys, Fe-Cr-Al alloys, Fe-Cu-Nb-Si-B alloys, Fe-Ni-Cr alloys called mumetals, and these alloys also have a relative permeability of 100 or more Is preferably used.

The soft magnetic metal powder used for the composite material (B) is preferably made of iron (Fe) or an iron (Fe) alloy. A soft magnetic metal powder made of such a material has a particularly high relative magnetic permeability, and is therefore preferable because the resulting molded article has better electromagnetic shielding properties. Moreover, it can be said that it is advantageous from the viewpoint of economy.
Moreover, when the soft magnetic metal powder is made of iron or an iron alloy, the flatness is preferably 2 or more. The flatness referred to here means the longest diameter of one particle of the soft magnetic metal powder when the soft magnetic metal powder is externally observed at a magnification of about 100 to 300 times using a scanning electron microscope or an optical microscope. When the major axis is L and the shortest axis is the minor axis S, the major axis is divided by the minor axis (L / S). In this way, about 100 particles of soft magnetic metal powder are measured and obtained. Is the average value. The major axis and minor axis will be described with reference to FIG. FIG. 1 is a schematic diagram showing the appearance of one particle of elliptical soft magnetic metal powder (elliptical metal powder). In such a case, the longest diameter L and the shortest diameter S of the elliptical metal powder particles are as shown in FIG. Thus, L and S are calculated | required from an external appearance, and the flatness per particle | grain of metal powder is calculated | required. Similarly, the flatness of about 100 metal powder particles is obtained and averaged, and the flatness is derived. If the flatness is 2 or more, when the liquid crystal polymer composition of the present invention is melt-molded, the major axis (axis in the major axis direction) of the component (B) is relative to the flow direction (MD) of the molten resin. It becomes easy to align. If the plane parallel to the MD is an electromagnetic wave shielding surface, the area occupied by the component (B) in this surface is likely to increase, and the electromagnetic wave shielding performance of the component (B) can be effectively utilized. In this respect, the flatness is preferably 2.5 or more.

The ceramic powder mainly containing silicon oxide of the composite material (B) used in the present invention is preferably a ceramic powder made of silicon oxide, and the silicon oxide contains impurities such as silicon nitride and silicon carbide if the amount is small. The organic group may be included as long as the amount is small.
Such ceramic powders can be easily obtained from the market in a variety of so-called silica. Such commercially available silica includes natural silica or synthetic silica (artificial silica). Examples of the synthetic silica include dry synthetic silica and wet synthetic silica. The natural silica is preferably obtained by pulverizing quartz from the point of high purity of silicon oxide, and natural silica produced by combining pulverization and melting from quartz can also be obtained with high purity of silicon oxide. Therefore, it is preferable. Examples of dry synthetic silica include those obtained by firing a mixture of silicon tetrachloride and hydrogen in air at about 1000 to 1200 ° C., those obtained by melting metal silicon and spraying it into the air from a nozzle, and the like. is there. The dry synthetic silica obtained by such a production method may contain Si—H bonds in a small amount in the silica. As the ceramic powder, those containing a trace amount of Si—H bonds can be used. The wet synthetic silica is obtained by hydrolyzing silicon tetrachloride, silicic acid alkoxide, or the like. The wet synthetic silica obtained by such a production method may contain organic substances and chlorine as reaction impurities, or may contain silanol groups (Si—OH) in the molecule. Further, the silanol group may be hydrated to have hydrated water. Such a wet synthetic silica can also be used for the composite material (B) used in the present invention. However, such a wet synthetic silica is subjected to a heat treatment at a high temperature of about 800 ° C. for hydration. Wet synthetic silica obtained by removing water and organic substances is preferred.
Such silica is available from, for example, Admatechs Co., Ltd., Tosoh Silica Co., Ltd., etc., and these are preferably used for producing the composite material (B).

The composite material (B) is manufactured using the ceramic powder as described above, preferably silica, and soft magnetic metal powder, preferably soft magnetic metal powder made of iron or iron alloy.
Here, a manufacturing method when iron powder is used as the soft magnetic metal powder will be briefly described.
The iron powder and the silica particles are mixed using a mixer that can be mixed in a dry manner, such as a ball mill, a planetary ball mill, or a sand mill. In this mixer, when a planetary ball mill is used, a composite material (B) in which silica particles are coated with iron powder can be obtained. When such a composite material (B) is used, the liquid crystal of the present invention is obtained. When a molded body is obtained from the polymer composition, the electrical insulation of the molded body tends to be even better. From such a viewpoint, it is preferable that the usage amount of the iron powder and the silica particles is selected so that the silica particles cover the iron powder and the weight ratio between the two is selected. In this case, several preliminary experiments with varying the weight ratio of iron powder and silica particles were performed, and the cross section of the composite material (B) obtained in the preliminary experiment was observed with, for example, a scanning electron microscope (SEM). It is only necessary to determine the weight ratio to be used by determining the coating state with silica particles. Moreover, when mixing iron powder and a silica particle, it is preferable to implement in the atmosphere of inert gas, such as nitrogen and argon, from a viewpoint which prevents the said iron powder from oxidizing remarkably.
A suitable composite material obtained by coating soft magnetic iron powder with silica particles can also be obtained from Hitachi High-Technologies Corporation. The composite material manufactured by Hitachi High-Technologies Corporation is described in the literature (Electronic Materials September 2008 issue).

  As the composite material (B) used in the present invention, it is not necessary that the ceramic powder covers the entire surface of the soft magnetic metal powder, and the degree to which the soft magnetic metal powders are prevented from contacting each other in the molded body. If it is.

<(A) Liquid crystal polymer>
Next, the component (A) liquid crystal polymer (hereinafter sometimes referred to as “liquid crystal polymer (A)”) used in the present invention will be described. Here, the liquid crystal polymer means a polymer that exhibits optical anisotropy when melted and forms an anisotropic melt at a temperature of 450 ° C. or lower. This optical anisotropy can be confirmed by a normal polarization inspection method using an orthogonal polarizer. The liquid crystal polymer has a long and narrow molecular shape, a flat and highly rigid molecular chain along the long chain of the molecule (this highly rigid molecular chain is usually referred to as a “mesogen group”). The mesogenic group only needs to be present in one or both of the polymer main chain and the side chain. However, if the obtained molded product requires higher heat resistance, the polymer main chain may have a mesogenic group. preferable.
Specific examples of the liquid crystal polymer include liquid crystal polyester, liquid crystal polyester amide, liquid crystal polyester ether, liquid crystal polyester carbonate, liquid crystal polyester imide, liquid crystal polyamide, and the like. Among these, a molded article having higher strength can be obtained. From the viewpoint, liquid crystal polyester, liquid crystal polyester amide, or liquid crystal polyamide is preferable, and liquid crystal polyester or liquid crystal polyester amide is preferable in that a molded article with lower water absorption can be obtained.

（式中、Ａｒ₁及びＡｒ₄はそれぞれ独立に、１，４−フェニレン基、２,６−ナフタレンジイル基又は４，４’−ビフェニリレン基を表す。Ａｒ₂、Ａｒ₃、Ａｒ₅及びＡｒ₆はそれぞれ独立に、１，４−フェニレン基、２,６−ナフタレンジイル基、１，３−フェニレン基又は４，４’−ビフェニリレン基を表す。また、Ａｒ₁、Ａｒ₂、Ａｒ₃、Ａｒ₄、Ａｒ₅及びＡｒ₆はは、その芳香環上の水素原子の一部又は全部が、ハロゲン原子、アルキル基、アリール基に置換されていてもよい。） Suitable liquid crystal polymers (A) include the following (A1), (A2), (A3), (A4), (A5) and (A6) (hereinafter referred to as “(A1) to (A6)”). A liquid crystal polymer selected from the group consisting of (which may be referred to as above) is preferred, and two or more liquid crystal polymers selected from these may be used in combination as the liquid crystal polymer (A).

(A1) Liquid crystal polyester comprising a repeating unit represented by the following (i);
(A2) Liquid crystalline polyester comprising a repeating unit represented by the following (ii) and a repeating unit represented by (iii);
(A3) Liquid crystalline polyester comprising a repeating unit represented by the following (i), a repeating unit represented by (ii), and a repeating unit represented by (iii);
(A4) Liquid crystal polyester amide or liquid crystal polyamide obtained by replacing a part or all of the repeating units represented by (i) in the above (A1) with the repeating units represented by (iv);
(A5) In the above (A2), part or all of the repeating unit represented by (iii) is replaced with the repeating unit represented by (v) and / or the repeating unit represented by (vi) Liquid crystal polyester amide or liquid crystal polyamide;
(A6) In (A3), part or all of the repeating unit represented by (iii) is replaced with the repeating unit represented by (v) and / or the repeating unit represented by (vi). , Liquid crystal polyester amide

(In the formula, Ar ₁ and Ar ₄ each independently represents a 1,4-phenylene group, a 2,6-naphthalenediyl group, or a 4,4′-biphenylylene group. Ar ₂ , Ar ₃ , Ar ₅ and Ar ₆ Each independently represents a 1,4-phenylene group, a 2,6-naphthalenediyl group, a 1,3-phenylene group, or a 4,4′-biphenylylene group, and Ar ₁ , Ar ₂ , Ar ₃ , Ar _4. In Ar ₅ and Ar ₆ , part or all of the hydrogen atoms on the aromatic ring may be substituted with a halogen atom, an alkyl group, or an aryl group.

  (I) The unit is a repeating unit derived from an aromatic hydroxycarboxylic acid, and examples of the aromatic hydroxycarboxylic acid include 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 7-hydroxy-2-naphthoic acid, 6-hydroxy-1-naphthoic acid, 4′-hydroxybiphenyl-4-carboxylic acid, or a part or all of hydrogen on the aromatic ring in these aromatic hydroxycarboxylic acids , An alkyl group, an aryl group, and an aromatic hydroxycarboxylic acid substituted with a halogen atom.

  (Ii) The unit is a repeating unit derived from an aromatic dicarboxylic acid, and examples of the aromatic dicarboxylic acid include terephthalic acid, phthalic acid, 4,4′-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, Examples include aromatic dicarboxylic acids in which part or all of hydrogen on the aromatic ring in isophthalic acid or these aromatic dicarboxylic acids is substituted with an alkyl group, an aryl group, or a halogen atom.

  (Iii) The unit is a repeating unit derived from an aromatic diol, and examples of the aromatic diol include hydroquinone, resorcin, naphthalene-2,6-diol, 4,4′-biphenylenediol, and 3,3′-. Biphenylene diol, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenyl sulfone, or a part or all of hydrogen on the aromatic ring in the aromatic diol is substituted with an alkyl group, an aryl group, or a halogen atom. An aromatic diol is given.

  (Iv) The unit is a repeating unit derived from an aromatic aminocarboxylic acid, and examples of the aromatic aminocarboxylic acid include 4-aminobenzoic acid, 3-aminobenzoic acid, 6-amino-2-naphthoic acid, Alternatively, aromatic aminocarboxylic acids in which part or all of hydrogen on the aromatic ring in these aromatic aminocarboxylic acids are substituted with alkyl groups, aryl groups, or halogen atoms can be mentioned.

  The unit (v) is a repeating unit derived from an aromatic amine having a hydroxy group, and includes 4-aminophenol, 3-aminophenol, 4-amino-1-naphthol, 4-amino-4′-hydroxydiphenyl, Alternatively, an aromatic hydroxyamine in which part or all of hydrogen on the aromatic ring in the aromatic amine having a hydroxy group is substituted with an alkyl group, an aryl group, or a halogen atom.

  (Vi) The unit is a structural unit derived from an aromatic diamine, and a part or all of hydrogen on the aromatic ring in 1,4-phenylenediamine, 1,3-phenylenediamine, or these aromatic diamines. , Aromatic diamines substituted with alkyl groups, aryl groups, and halogen atoms.

Here, as described above, these structural units may optionally have a substituent. This substituent will be briefly exemplified.
Examples of the alkyl group include a straight chain, branched or branched chain having 1 to 10 carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, a hexyl group, a cyclohexyl group, an octyl group, and a decyl group. An alicyclic alkyl group is mentioned.
Examples of the aryl group include aryl groups having 6 to 10 carbon atoms such as a phenyl group and a naphthyl group.
The halogen atom is selected from a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

  Among the above-mentioned liquid crystal polymers (A), a liquid crystal polyester selected from the group consisting of (A1) to (A3) is preferable in that a molded article having more excellent heat resistance and dimensional stability can be obtained, and (A1) or The liquid crystalline polyester (A3) is particularly preferred.

Hereinafter, the liquid crystal polyester (A1) or (A3) which is a liquid crystal polymer (A) particularly suitable in the present invention will be described in detail.
As described above, the liquid crystalline polyester (A1) is composed of (i) units, and preferably has a plurality of types of (i) units. The reason is that it is excellent in balance between heat resistance and molding processability.

The liquid crystal polyester (A3) has (i) units, (ii) units, and (iii) units. When the total of these is 100 mol%, the total of (i) units is 30 to 80. Preferably, the total of (ii) units is 10 to 35 mol%, and (iii) the total of units is 10 to 35 mol%. In addition, the molar polymerization ratio of (ii) units and the molar polymerization ratio of (iii) units are expressed as (ii) units / (iii) units, and 0.9 / 1.0 to 1.0 / 0.9. When the liquid crystal polyester is produced, a carboxyl group capable of forming an ester bond is substantially equal [(ii) unit / (iii) unit = 1.0 / 1.0]. Since the number of hydroxy groups is the same, the obtained liquid crystal polyester can be made high in molecular weight, which is advantageous in obtaining a molded product having more excellent heat resistance.
Here, when the unit (i) is less than 30 mol%, or when the unit (ii) and / or the unit (iii) exceeds 35 mol%, the resulting polyester tends to hardly exhibit liquid crystallinity. .
On the other hand, when the unit (i) exceeds 80 mol%, or when the unit (ii) and / or the unit (iii) is less than 10 mol%, the obtained liquid crystal polyester is difficult to melt and the moldability is lowered. There is a tendency.
Further, the unit (i) is more preferably 40 to 70 mol%, and particularly preferably 45 to 65 mol%.
On the other hand, the unit (ii) and the unit (iii) are each more preferably 15 to 30 mol%, and particularly preferably 17.5 to 27.5 mol%, respectively.

  Next, a preferred method for producing the liquid crystal polyester (A1) or (A3) will be described. In order to obtain such a liquid crystal polyester, raw material monomers for deriving the liquid crystal polyester, that is, a plurality of kinds of aromatic hydroxycarboxylic acids, or aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids and aromatic diols are known means. Can be obtained by polymerization. Among these, from the viewpoint of ease of liquid crystal polyester production, it is preferable to produce the liquid crystal polyester after converting the raw material monomer into an ester-forming derivative in advance.

  Here, the ester-forming derivative will be described. The ester-forming derivative has a group that promotes the ester formation reaction. Specifically, in the case of a raw material monomer having a carboxyl group in the molecule, the carboxyl group is converted to an acid halide, an acid. It can be converted to an anhydride to improve the ester forming property, or the carboxyl group can form an ester bond with a transesterification reaction so that an ester group is formed with a lower alcohol. Moreover, in the case of the raw material monomer which has a hydroxyl group in a molecule | numerator, ester formation property can be improved by converting this hydroxy group into a lower carboxylate group.

  In the production of liquid crystal polyester using such an ester-forming derivative, a method using an ester-forming derivative obtained by converting the hydroxy group of an aromatic hydroxycarboxylic acid and aromatic diol to a lower carboxylic acid ester group is particularly suitable. As the lower carboxylic acid group, an acyl group is particularly preferable. Acylation can usually be achieved by reacting a compound having a hydroxy group with acetic anhydride. Such an ester-forming derivative can be subjected to deacetic acid polymerization (melt polymerization) together with an aromatic dicarboxylic acid to obtain a liquid crystal polyester.

  The liquid crystal polyester production method using the ester-forming derivative is, for example, the method described in JP-A-61-69866 for the liquid crystal polyester of (A1), and the method of liquid crystal polyester of (A3), for example, JP Known methods such as the method described in JP 2002-146003 A can be applied. That is, after mixing the monomers corresponding to the units (i), (ii) and (iii) and acylating with acetic anhydride to form an ester-forming derivative, a raw material containing the ester-forming derivative A monomer can be melt polymerized to obtain a liquid crystal polyester.

Here, in the case of aiming at a molded article having further excellent heat resistance, it is preferable to use the liquid crystalline polyester obtained by the melt polymerization as a prepolymer, and to further increase the molecular weight of the prepolymer. For this, it is advantageous to use solid-state polymerization. This solid phase polymerization will be briefly described. There is a method in which the prepolymer is pulverized to form a powder, and this powder is heated to perform solid phase polymerization. In such solid phase polymerization, the polymerization can be further advanced to increase the molecular weight.
In order to make the prepolymer into a powder, for example, the prepolymer may be cooled and solidified and then pulverized. The average particle size of the powder obtained by pulverization is preferably in the range of about 0.05 mm to 3 mm, and more preferably in the range of about 0.05 mm to 1.5 mm because higher molecular weight of the liquid crystal polyester is further promoted. . In addition, if the average particle size is within this range, sintering between particles does not occur, so that the operability of solid phase polymerization tends to be good, and the increase in the molecular weight of liquid crystal polyester is promoted efficiently. More preferred. In addition, the average particle diameter of a prepolymer is calculated | required by external appearance observation.

The thing suitable about the heating conditions in a solid phase polymerization is illustrated. First, the temperature is raised from room temperature to a temperature 20 ° C. or more lower than the flow start temperature of the prepolymer. The temperature raising time at this time is not particularly limited, but is preferably within 1 hour from the viewpoint of shortening the reaction time.
Next, the temperature is raised from a temperature 20 ° C. or more lower than the flow start temperature of the prepolymer to a temperature of 280 ° C. or more. The temperature increase is preferably performed at a temperature increase rate of 0.3 ° C./min or less, more preferably from 0.1 to 0.15 ° C./min. When the rate of temperature rise is 0.3 ° C./min or less, sintering between the particles of the powder is less likely to occur, and a higher molecular weight liquid crystal polyester can be produced.
In order to further increase the molecular weight of the liquid crystalline polyester, it is preferable to carry out the reaction at a temperature of 280 ° C. or higher, preferably in a temperature range of 280 ° C. to 400 ° C. for 30 minutes or longer in the final step of the solid phase polymerization. In particular, from the viewpoint of improving the thermal stability of the liquid crystalline polyester, it is preferable to react at a reaction temperature of 280 to 350 ° C. for 30 minutes to 30 hours, and at a reaction temperature of 285 to 340 ° C. for 30 minutes to 20 hours. Is more preferable. Such heating conditions are preferably optimized as appropriate depending on the type of raw material monomer used in the production of the liquid crystalline polyester. The details of the flow start temperature here will be described later.

The liquid crystalline polyester (A3) obtained by performing the solid phase polymerization can achieve a sufficiently high molecular weight, and a molded product excellent in heat resistance can be obtained. Preferably, it is a liquid crystal polyester having a flow start temperature of 280 ° C. or higher, and the flow start temperature is more preferably 280 to 390 ° C.
The flow start temperature is a capillary rheometer equipped with a die having an inner diameter of 1 mm and a length of 10 mm, and the liquid crystalline polyester is heated at a rate of temperature rise of 4 ° C./min under a load of 9.8 MPa (100 kg / cm ² ). This means a temperature at which the melt viscosity shows 4800 Pa · s (48000 poise) when extruding from a nozzle, and the flow start temperature is an index representing the molecular weight of a liquid crystal polyester known in the art (Naoyuki Koide, See "Liquid Crystalline Polymer Synthesis / Molding / Application-", pages 95-105, CMC, issued on June 5, 1987. In the present invention, as an apparatus for measuring the flow start temperature, Shimadzu Corporation Flow characteristics evaluation apparatus “Flow Tester CFT-500D” is used).

  The liquid crystal polyester (A1) or (A3) particularly suitable as the liquid crystal polymer (A) used in the present invention has been described above, but other liquid crystal polymers [liquid crystal polyesters (A2), (A4) to (A6)] With regard to the above, the production method using the ester-forming derivative or amide-forming derivative as described above can be easily produced.

<Other ingredients>
The liquid crystal polymer composition of the present invention may contain an additive such as a reinforcing agent depending on necessary properties as long as the electromagnetic wave shielding properties and electrical insulation properties of the obtained molded product are not significantly impaired.
Here, examples of the additive include fibrous reinforcing agents such as glass fiber, silica alumina fiber, alumina fiber, and carbon fiber; acicular reinforcing agents such as aluminum borate whisker and potassium titanate whisker; glass beads, talc, mica Inorganic fillers such as graphite, wollastonite and dolomite; mold release improvers such as fluororesins and metal soaps; colorants such as dyes and pigments; antioxidants; thermal stabilizers; UV absorbers; A surfactant or the like. Two or more of these additives may be used in combination.

  It is also possible to use additives having an external lubricant effect such as higher fatty acids, higher fatty acid esters, higher fatty acid metal salts, fluorocarbon surfactants and the like. Further, if the amount is small, a thermoplastic resin other than the liquid crystal polymer (for example, polyamide, crystalline polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyphenylene ether and its modified product, polysulfone, polyethersulfone, polyetherimide, etc.) Or a thermosetting resin (for example, phenol resin, epoxy resin, etc.). When using a thermoplastic resin or a thermosetting resin other than such a liquid crystal polymer, it is necessary to select the type and amount of addition so as not to impair the liquid crystal properties and moldability of the liquid crystal polymer itself.

<Method for producing liquid crystal polymer composition>
Next, a method for producing the liquid crystal polymer composition of the present invention will be described.
The liquid crystal polymer composition can be obtained by mixing the component (A) and the component (B) by various known means, but the component (A) and the component can be obtained at a lower cost. It is preferable to produce a liquid crystal polymer composition by melt-kneading the component (B), and it is particularly preferable to obtain a liquid crystal polymer composition in the form of pellets by extrusion melt-kneading.
In addition, as above-mentioned, in this liquid crystal polymer composition, it is necessary for the content weight of a component (B) to be more than the content weight of a component (A). Specifically, the composite material (B) is preferably 100 to 450 parts by weight, more preferably 100 to 300 parts by weight, and 100 to 250 parts by weight with respect to 100 parts by weight of the liquid crystal polymer (A). Is more preferable, and 100 to 200 parts by weight is particularly preferable. When the blending amount of the composite material (B) with respect to the liquid crystal polymer (A) is in such a range, the balance between the electromagnetic wave shielding property and the moldability becomes better. In addition, when using multiple types of composite material (B) as a component (B), the total amount shall be in the said range, and similarly, multiple types of liquid crystal polymer (A) is used as a component (A). If so, the total amount is within the above range.

A method using an extruder (melt kneading extruder) which is a preferred method for producing a liquid crystal polymer composition will be described.
The melt-kneading extruder includes a cylinder provided with heating means and a screw for extruding a heated melt into the cylinder, and is provided so that one screw is rotationally driven in the cylinder. Both the single-screw kneading extruder and the twin-screw kneading extruder composed of two screws provided so as to be rotationally driven in different directions or in the same direction in the cylinder can be used. However, the use of a twin-screw kneading extruder is advantageous for the liquid crystal polymer composition of the present invention.

As the melt-kneading extruder, when the ratio (L / D) of the effective length (L) of the screw to the screw diameter (D) is 20 or more (L and D are the same scale unit), the component ( Since A) and a component (B) are disperse | distributed more uniformly, it is preferable. In addition, the effective length of a screw here means the axial direction length of the groove | channel of a screw, and a screw diameter means the outer-diameter dimension of a screw.
The melt-kneading extruder is provided with a plurality of supply ports for supplying various components for forming a heated melt to the extruder. In order to obtain a liquid crystal polymer composition of the present invention in the form of pellets by forming a heated melt from the component (A) and the component (B), reinforcing agents and additives added as necessary, first, The component (B) is added to the total supply amount so that 90% by weight or more of the total supply amount of the component (A) is supplied from the upstream supply port provided on the upstream side in the extrusion direction of the melt-kneading extruder. It is fed to the melt-kneading extruder so that 50% by weight or less is fed. The remainder of component (A) [total supply amount of component (A) −supply amount of component (A) supplied from the upstream supply port] and the remainder of component (B) [total supply of component (B) Amount—a supply amount of the component (B) supplied from the upstream supply port] is supplied to the melt-kneading extruder from a downstream supply port provided downstream of the upstream supply port in the extrusion direction. By doing so, the contact time between the component (A) and the component (B) in the heated melt is relatively short, and the deterioration of the liquid crystal polymer (A) tends to be suppressed. This is advantageous for the production of liquid crystal polymer compositions. In this respect, the supply amount of the component (A) from the upstream supply port is preferably 95% by weight or more with respect to the total supply amount. The supply amount of the component (B) from the upstream supply port is more preferably 20% by weight or less with respect to the total supply amount. In particular, it is preferable that only the component (A) is supplied from the upstream supply port and only the component (B) is supplied from the downstream supply port from the viewpoint of reducing the complexity during production. In addition, when using the above reinforcing agent for the liquid crystal polymer composition of this invention, it is preferable that this reinforcing agent is supplied with a component (B) from the said downstream supply port.

  In order to turn the liquid crystal polymer composition of the present invention into a heated melt in the melt-kneading extruder cylinder, the cylinder is heated. In general, the heating temperature in this case is preferably Tp [° C.] or more and Tp +60 [° C.] or less, based on the flow start temperature Tp [° C.] of the liquid crystal polymer (A) to be used, and Tp +10 [° C.] or more and Tp +50 [° C.] or less is more preferable. The cylinder may be provided with a plurality of heating devices. In this case, the average heating temperature of the heating device provided from the downstream supply port to the die at the tip of the melt-kneading extruder may be in the above range.

  The liquid crystal polymer composition of the heated melt extruded from the melt kneading extruder becomes a string-like composition (strand) and is discharged from the die of the extruder. The liquid crystal polymer composition of the present invention is obtained in the form of pellets by a series of operations such as cooling and solidifying the strands as necessary and cutting the strands. In addition, the hot-cut method of cut | disconnecting and processing into a pellet with a die cutter immediately after discharging from the die | dye of an extruder, without cooling and solidifying the said strand can also be used. However, when the strand method and the hot cut method are compared from the viewpoint of productivity, the strand method is advantageous in that the productivity becomes better.

<Molded body and molding method thereof>
The liquid crystal polymer composition of the present invention can produce a molded body by various known molding methods. As the molding method, various molding methods generally used in the field of thermoplastic resins, such as injection molding, extrusion molding, transfer molding, blow molding, press molding, injection press molding, and extrusion injection molding, can be used. A plurality of these molding methods may be combined. A person skilled in the art can select a preferable molding method and molding conditions according to the shape of the target molded product. Among these, injection molding or extrusion injection molding is preferable, and injection molding is particularly preferable for manufacturing parts used in electronic devices.

Here, the injection molding which is a suitable molding method will be described.
For injection molding, for example, an injection molding machine such as a hydraulic horizontal molding machine PS40E5ASE manufactured by Nissei Plastic Industry Co., Ltd. is used to melt the liquid crystal polymer composition of the present invention, and the molten liquid crystal polymer composition is brought to an appropriate temperature. It is heated and injected into a mold having the desired cavity shape. The temperature at which the liquid crystal polymer composition is heated and melted for injection is Tp ′ + 10 [° C.] or more and Tp ′ + 50 [° C.] or less, based on the flow start temperature Tp ′ [° C.] of the liquid crystal polymer composition to be used. . Moreover, the temperature of a metal mold | die is normally selected from the range of room temperature-180 [degreeC] from the point of the cooling rate and productivity of a liquid crystal polymer composition.

The liquid crystal polymer composition of the present invention can obtain a molded article suitable as an electromagnetic wave shielding member in an electronic component by optimizing the molding method. Specifically, when the electrical insulation is expressed by volume resistivity, it is 10 ⁸ Ωm or more, and as the electromagnetic wave shielding property, when expressed by a shielding effect against high frequencies, a practically sufficient electromagnetic wave shielding member of 3 dB or more is obtained. Obtainable. In addition, the high frequency here is a frequency of 2.5 GHz or more, for example.

  Further, such a molded body is suitably used for surface mount components by taking advantage of its electrical insulation and electromagnetic shielding properties. Examples of such surface mount components include electronic component housings, choke coils, connectors, and the like. The surface-mounted component using the liquid crystal polymer composition of the present invention is extremely useful because it is expected to absorb electronic noise.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by these Examples.

The following fillers were used as the component (B).
Filler 1
(Electromagnetic wave absorbing filler, manufactured by Hitachi High-Technologies Corporation,
Volume average particle size 20 μm, flatness 2.7)

Production Example 1 [Production of Liquid Crystalline Polyester]
To a reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer and a reflux condenser, 994.5 g (7.2 mol) of parahydroxybenzoic acid, 446.9 g of 4,4′-dihydroxybiphenyl (2 4 mol), 299.0 g (1.8 mol) of terephthalic acid, 99.7 g (0.6 mol) of isophthalic acid, and 1347.6 g (13.2 mol) of acetic anhydride, and the reactor was sufficiently filled with nitrogen. After replacing with gas, the temperature was raised to 150 ° C. over 30 minutes under a nitrogen gas stream, and the mixture was refluxed for 1 hour while maintaining the temperature.
Thereafter, while distilling off by-product acetic acid and unreacted acetic anhydride, the temperature was raised to 320 ° C. over 2 hours and 50 minutes, and when the increase in torque was observed, the reaction was completed and a prepolymer was obtained.
The obtained prepolymer was cooled to room temperature and pulverized with a coarse pulverizer to obtain a powder. This powder was heated in a nitrogen atmosphere from room temperature to 250 ° C. over 1 hour, heated from 250 ° C. to 285 ° C. over 5 hours, and maintained at that temperature for 3 hours. The liquid crystal polyester obtained by cooling had a flow start temperature of 327 ° C. The liquid crystal polyester thus obtained is designated as LCP1.

Examples 1 and 2 and Comparative Example 1
The LCP1 obtained in Production Example 1 and the filler 1 shown above were blended at 330 ° C. using the same direction twin screw extruder (Ikegai Iron Works Co., Ltd., PCM-30HS) with the composition shown in Table 1 to form a pellet. A liquid crystal polymer composition (pellet) was obtained. At this time, the total supply amount of LCP1 was supplied from the upstream supply port of the same-direction twin screw extruder, and the total supply amount of filler 1 was supplied from the downstream supply port of the same-direction twin screw extruder.
The obtained pellets were injection molded at a cylinder temperature of 350 ° C., a mold temperature of 130 ° C., and an injection rate of 30 cm ³ / s using an injection molding machine (Nissei Plastic Industries, Ltd. PS40E5ASE type), and a rectangular parallelepiped of 64 mm × 64 mm × 1 mm A molded body of was obtained.
The shielding effect and volume resistivity value of the molded body thus obtained were determined. The results are shown in Table 1.

In addition, the shielding effect and volume specific resistance which are the characteristic evaluation of a molded object were calculated | required as follows.

[Electromagnetic shielding value measurement method]
The electromagnetic wave shielding value at a frequency of 2.5 GHz was measured with a coaxial tube type conforming to ASTM D4935.

[Volume resistivity measurement method]
Based on ASTM D257, volume resistivity was determined with a SM-10E type super insulation meter manufactured by Toa Denpa Kogyo Co., Ltd.

It is a schematic diagram showing the external appearance of the particle | grains of elliptical soft magnetic metal powder.

Explanation of symbols

1 ... Particles of elliptical soft magnetic metal powder L ... Major axis S ... Minor axis

Claims (10)

A liquid crystal polymer composition comprising the following component (A) and component (B), wherein the content of component (B) is equal to or greater than the content of component (A).
(A) Liquid crystal polymer (B) Composite material of ceramic powder containing silicon oxide as main component and soft magnetic metal powder   The liquid crystal polymer composition according to claim 1, comprising 100 to 450 parts by weight of the component (B) with respect to 100 parts by weight of the component (A).   The liquid crystal polymer composition according to claim 1 or 2, wherein the component (B) is a composite material obtained by coating the soft magnetic metal powder with the insulating ceramic powder.   The liquid crystal polymer composition according to any one of claims 1 to 3, wherein the soft magnetic metal powder constituting the component (B) is a soft magnetic metal powder made of iron or an iron alloy.   The liquid crystal polymer composition according to any one of claims 1 to 3, wherein the soft magnetic metal powder constituting the component (B) is made of iron or an iron alloy and has a flatness ratio of 2 or more. The component (A) is at least one liquid crystal polyester selected from the group consisting of the following (A1), (A2) and (A3). Liquid crystal polymer composition.
(A1) Liquid crystalline polyester composed of repeating units represented by (i) below (A2) Liquid crystalline polyester composed of repeating units represented by (ii) below and (iii) (A3) Liquid crystalline polyester comprising repeating units represented by i), (ii) and (iii)

(In the formula, Ar ₁ represents a 1,4-phenylene group, a 2,6-naphthalenediyl group, or a 4,4′-biphenylylene group. Ar ₂ and Ar ₃ are each independently a 1,4-phenylene group, 2,6-naphthalenediyl group, 1,3-phenylene group or 4,4′-biphenylylene group, and Ar ₁ , Ar _2, and Ar ₃ are all or part of hydrogen atoms on the aromatic ring. , May be substituted with a halogen atom, an alkyl group, or an aryl group.)   The liquid crystal polymer composition according to claim 6, wherein the component (A) comprises the liquid crystal polyester (A3).   A melt kneading extruder having a ratio (L / D) of the effective length (L) to the screw diameter (D) of 20 or more (L and D are the same scale unit) is used. The component (B) is added to the total supply amount of 50% so that 90% by weight or more of the component (A) is supplied from the upstream supply port provided in the upstream portion in the extrusion direction. The remaining part of the component (A) and the component are supplied to the melt-kneading extruder from the downstream supply port provided on the downstream side in the extrusion direction from the upstream supply port so that the weight% or less is supplied. The component (A) and the component (B) are obtained by melt-kneading by supplying the remainder of (B) to the melt-kneading extruder. A liquid crystal polymer composition as described in 1.   A molded article obtained by molding the liquid crystal polymer composition according to claim 1.   The molded product according to claim 9, wherein the molded product is used as a surface-mounted component.

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