JP2002194194A - Semiconductive resin composition and molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductive liquid crystal polymer composition imparted with stable antistaticity without greatly deteriorating mechanical properties, which is especially suitable for manufacturing electronic parts items. SOLUTION: The semiconductive resin composition having a volume resistivity of 1×104 to 1×1011 Ω.cm comprises: (A) 100 pts.wt. of a liquid crystal polymer; and (B) 1 to 50 pts.wt. of carbon fibers of PAN-base wherein carbon fibers (B) are dispersed in the composition at a weight average of fiber length with 50 to 350 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal polymer composition containing a specific PAN-based carbon fiber or graphite, and more particularly, to the molding of an electronic component requiring antistatic performance. The present invention relates to a semiconductive liquid crystal polymer composition suitably used.

[0002]

2. Description of the Related Art Liquid crystalline polymers capable of forming an anisotropic molten phase are excellent in dimensional accuracy, vibration damping properties and fluidity among thermoplastic resins, and cause burrs during molding. Known as very few materials. Conventionally, a liquid crystal polymer composition reinforced with glass fibers utilizing such characteristics has been widely used as an electronic component.
However, in recent years, the contact and
There is a problem that static electricity is generated due to sliding, and in order to prevent this, it is necessary to add a conductive filler to the plastic material of the molded product and to provide antistatic performance to itself. Have been done.

For example, Japanese Patent Application Laid-Open No. Sho 62-131067 discloses an attempt to improve the conductivity by blending a conductive carbon black with a liquid crystalline polymer. According to this method, the conductivity is improved, but the volume resistance is improved. Rate is 1 × 10 ¹ Ω
-Cm or less, which has an antistatic effect, but the molded article itself becomes conductive, so that it cannot be used for parts requiring insulation. As described above, when conductive carbon black is used, it is difficult to control the volume resistivity in the range of 1 × 10 ⁴ to 1 × 10 ¹¹ Ω · cm, which does not exhibit conductivity and has an antistatic effect. Also, JP-A-6-207083 and JP-A-20
JP-A-281885 attempts to improve the antistatic property by blending graphite as a conductive filler. However, when only graphite is used as the conductive filler, control of the surface resistance is excellent. However, in order to exhibit antistatic properties, the filling amount of graphite or the like becomes too large, and there is a decrease in fluidity and mechanical properties, which is not practical. Further, JP-A-63-146959 and JP-A-4-31758.
JP, JP-A-6-93173, JP-A-6-17
Japanese Patent No. 2619 discloses an attempt to improve the slidability by blending graphite and / or pitch-based carbon fiber. Although the slidability is improved, it is difficult to control the volume resistivity, and the molding is difficult. There was no material that could solve all of the above-mentioned problems because the volume resistivity of the product had a large fluctuation.

[0004]

Means for Solving the Problems In view of the above problems, the present inventors have conducted intensive searches and studies on materials having excellent antistatic properties, and found that a PAN-based carbon fiber specific to a liquid crystal polymer was used. Alternatively, it has been found that by blending graphite in a specific blending amount, a stable antistatic property can be imparted without significantly lowering the mechanical properties, and the present invention has been completed.

That is, the present invention provides a composition comprising 100 parts by weight of a liquid crystalline polymer (A) and 1 to 50 parts by weight of a PAN-based carbon fiber (B). A semiconductive resin composition having a weight average fiber length of 50 to 350 μm dispersed in the composition and a volume resistivity of 1 × 10 ⁴ to 1 × 10 ¹¹ Ωcm;
And 100% by weight of liquid crystalline polymer (A), 1 to 50 parts by weight of PAN-based carbon fiber (B), and 95% by weight or more of fixed carbon graphite.
(C) 1 to 50 parts by weight (however, the total amount of components (B) and (C) is
(A) 25 to 100 parts by weight per 100 parts by weight), wherein the PAN-based carbon fiber (B) is dispersed in the composition at a weight average fiber length of 50 to 350 μm. And a semiconductive resin composition having a volume resistivity of 1 × 10 ⁴ to 1 × 10 ¹¹ Ω · cm.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The liquid crystalline polymer (A) used in the present invention refers to a melt-processable polymer having a property capable of forming an optically anisotropic molten phase. The properties of the anisotropic molten phase can be confirmed by a conventional polarization inspection method using an orthogonal polarizer. More specifically, the anisotropic molten phase can be confirmed by using a Leitz polarizing microscope and observing the molten sample placed on the Leitz hot stage at a magnification of 40 times under a nitrogen atmosphere. When the liquid crystalline polymer applicable to the present invention is inspected between orthogonal polarizers, polarized light is normally transmitted even when it is in a molten stationary state, and exhibits optical anisotropy.

The liquid crystalline polymer (A) as described above is not particularly limited, but is preferably an aromatic polyester or an aromatic polyesteramide, and the aromatic polyester or the aromatic polyesteramide is partially contained in the same molecular chain. Is included in the range. These are pentafluorophenol at a concentration of 0.1% by weight at 60 ° C.
Preferably at least about 2.0 dl when dissolved in
/ G, more preferably 2.0 to 10.0 dl / g, having an intrinsic viscosity (IV).

The aromatic polyester or aromatic polyesteramide as the liquid crystalline polymer (A) applicable to the present invention is particularly preferably at least one selected from the group consisting of aromatic hydroxycarboxylic acids, aromatic hydroxyamines and aromatic diamines. Aromatic polyesters and aromatic polyesteramides having one or more compounds as constituents.

More specifically, (1) a polyester mainly comprising one or more aromatic hydroxycarboxylic acids and derivatives thereof; (2) mainly (a) an aromatic hydroxycarboxylic acid and one derivative thereof Or two or more of (b) one or more of aromatic dicarboxylic acids, alicyclic dicarboxylic acids and derivatives thereof, and (c) aromatic diols, alicyclic diols, aliphatic diols and derivatives thereof. (3) mainly (a) one or more aromatic hydroxycarboxylic acids and derivatives thereof, and (b) aromatic hydroxyamines, aromatic diamines and the like. From one or more kinds of derivatives and (c) one or more kinds of aromatic dicarboxylic acids, alicyclic dicarboxylic acids and derivatives thereof (4) mainly (a) one or more aromatic hydroxycarboxylic acids and derivatives thereof, and (b) one or more aromatic hydroxyamines, aromatic diamines and derivatives thereof. , (C) one or more aromatic dicarboxylic acids, alicyclic dicarboxylic acids and derivatives thereof,
(D) Polyester amide comprising at least one kind or two or more kinds of aromatic diols, alicyclic diols, aliphatic diols and derivatives thereof, and the like. Further, a molecular weight modifier may be used in combination with the above-mentioned components as needed.

The liquid crystalline polymer applicable to the present invention.
Preferred examples of the specific compound constituting (A) include p
-Hydroxybenzoic acid, aromatic hydroxycarboxylic acids such as 6-hydroxy-2-naphthoic acid, 2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene,
4,4′-dihydroxybiphenyl, hydroquinone,
Resorcinol, the following general formula (I) and the following general formula (II)
Aromatic diols such as compounds represented by the following; terephthalic acid,
Isophthalic acid, 4,4′-diphenyldicarboxylic acid,
2,6-naphthalenedicarboxylic acid and the following general formula (II
Aromatic dicarboxylic acids such as the compounds represented by I); and aromatic amines such as p-aminophenol and p-phenylenediamine.

[0011]

Embedded image

(Provided that X is a group selected from alkylene (C ₁ -C ₄ ), alkylidene, —O—, —SO—, —SO ₂ —, —S—, and —CO—, and Y: — (CH _{2 ) n - (n = 1~4)} , - O (CH 2) n O- (n =
Groups selected from 1-4) The particularly preferred liquid crystalline polymer (A) to which the present invention is applied is p-hydroxybenzoic acid, 6-hydroxy-2
-An aromatic polyester containing naphthoic acid as a main constituent unit.

In order to provide a stable antistatic property without greatly deteriorating the mechanical properties, which is the object of the present invention, 100 parts by weight of the liquid crystalline polymer (A) is added to 100 parts by weight of the PAN-based carbon fiber (B) 1. 5050 parts by weight, weight average fiber length 50 in the composition
It must be blended to disperse at ~ 350 μm.

The PAN-based carbon fiber (B) used in the present invention is a carbon fiber made of polyacrylonitrile, and a milled carbon fiber or a chopped carbon fiber produced by grinding or cutting it is used. . In the present invention, the weight average fiber length of the PAN-based carbon fiber (B) is important. If it is too short, the antistatic effect is not exhibited, and if it is too long, the dispersion of the conductivity becomes large, and the stable antistatic effect is obtained. Is not expressed. Therefore, it is necessary that the weight average fiber length is 50 to 350 μm. When the amount of the PAN-based carbon fiber (B) is large, the mechanical properties are improved, but
Extrudability and moldability deteriorate, and conductivity becomes too good to cause conduction. On the other hand, when the compounding amount is small, conductivity is not exhibited and the antistatic effect is inferior. Therefore, the blending amount of the PAN-based carbon fiber (B) is limited to the range of 1 to 50 parts by weight, preferably 5 to 25 parts by weight based on 100 parts by weight of the liquid crystalline polymer (A).

Next, in the present invention, the weight average fiber length is 50 to
It is preferable to mix graphite (C) with 95% by weight or more of fixed carbon in combination with PAN-based carbon fiber (B) of 350 μm from the viewpoint of exhibiting more stable antistatic properties.

As the graphite (C) used herein, any kind of graphite such as artificial graphite and natural graphite such as flaky graphite, flaky graphite, earthy graphite and the like can be used. In order to impart electrical conductivity, it is necessary to use graphite having 95% by weight or more, preferably 98% by weight or more of fixed carbon. Among these, from the aspect of performance,
Preference is given to artificial graphite having a high fixed carbon ratio, flaky graphite or flaky graphite, which easily forms a structure in a molded article.

In the present invention, when the PAN-based carbon fiber (B) and the graphite (C) are used in combination, in order to provide good extrudability, moldability and mechanical properties, and to provide stable antistatic properties. The amount of PAN-based carbon fiber (B) and graphite (C) is important, and the individual and total amounts must be within a specific range.

That is, if the compounding amount of graphite (C) is large, the extrudability and the formability are deteriorated and the mechanical strength is reduced. On the other hand, when the compounding amount is small, conductivity is not exhibited and the antistatic effect is inferior. At this time, if conductivity is to be imparted by increasing the blending amount of the PAN-based carbon fiber (B), the variation in conductivity is increased, and a stable conductivity preventing effect is not exhibited. Therefore, the amount of graphite (C) is limited to the range of 1 to 50 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the liquid crystalline polymer (A).

The amount of the PAN-based carbon fiber (B) is as follows:
When the amount is large, the mechanical properties are improved, but the extrudability,
The moldability is deteriorated, and the conductivity is too high to cause conduction. On the other hand, when the compounding amount is small, conductivity is not exhibited and the antistatic effect is inferior. At this time, when an attempt is made to impart conductivity by increasing the blending amount of the graphite (C), the extrudability and the moldability are deteriorated as described above, and the mechanical strength is reduced. Therefore, the blending amount of the PAN-based carbon fiber (B) is limited to the range of 1 to 50 parts by weight, preferably 5 to 25 parts by weight based on 100 parts by weight of the liquid crystalline polymer (A).

When the total amount of the components (B) and (C) is too large, the extrudability and the moldability are deteriorated when the amount is too large.
If the compounding amount is small, the conductivity is not stable, and the mechanical strength is also reduced.Therefore, 25 to 100 parts by weight, preferably 30 to 80 parts by weight, more preferably 30 to 80 parts by weight based on 100 parts by weight of the liquid crystalline polymer (A). 35 to 50 parts by weight.

In addition, various fibrous and non-fibrous fillers can be added to the composition of the present invention as long as the desired antistatic performance of the present invention is not impaired.

As the fibrous filler, glass fibers, whiskers, inorganic fibers, ore fibers and the like can be used. As whiskers, silicon nitride whiskers, silicon trinitride whiskers, basic magnesium sulfate whiskers, barium titanate whiskers, silicon carbide whiskers, boron whiskers, etc. can be used.As inorganic fibers, rock wool, zirconia, alumina silica Various fibers such as potassium titanate, barium titanate, titanium oxide, silicon carbide, alumina, silica, and blast furnace slag can be used, and as ore-based fibers, asbestos and the like can be used. Among these, glass fibers are preferable from the viewpoint of performance.

The plate-like or powdery non-fibrous fillers include
Specifically, silicates such as talc, mica, kaolin, clay, graphite, vermiculite, calcium silicate, aluminum silicate, feldspar powder, acid clay, limestone clay, sericite, sillimanite, bentonite, glass flakes, slate powder, and silane , Calcium carbonate, chalk,
Carbonates such as barium carbonate, magnesium carbonate, dolomite, barite powder, branfix, precipitated calcium sulfate, plaster of Paris, sulfates such as barium sulfate, hydroxides such as hydrated alumina, alumina, antimony oxide, magnesia, and oxidation It is composed of oxides such as titanium, zinc white, silica, silica sand, quartz, white carbon, diatomaceous earth, sulfides such as molybdenum disulfide, and metal powders.

The PAN-based carbon fiber, graphite and filler used in the present invention can be used as they are, but commonly used well-known surface treatment agents and sizing agents can be used in combination.

In addition, nucleating agents, carbon black, pigments such as inorganic calcined pigments, and additives such as antioxidants, stabilizers, plasticizers, lubricants, release agents and flame retardants are added to the liquid crystal polymer composition. A composition having desired properties is also included in the range of the liquid crystalline polymer composition according to the present invention.

In the liquid crystalline polymer composition of the present invention,
In particular, when PAN-based carbon fiber and graphite are used in combination, without compromising the mechanical properties by compensating for the respective disadvantages,
A material with excellent antistatic properties is obtained, and furthermore, each filler in the molded body is dispersed uniformly, and a higher performance is exhibited in a dispersed state in which graphite is present between PAN-based carbon fibers. Is done.

In order to produce such a liquid crystalline polymer composition, the liquid crystal polymer composition may be blended at the above composition ratio and kneaded. Usually, the mixture is kneaded by an extruder, extruded into pellets, and used for injection molding, but is not limited to kneading by such an extruder.

The object of the present invention is achieved when the weight average fiber length of the PAN-based carbon fiber is in the range of 50 to 350 μm in the composition, and the composition of the present invention can be obtained by setting such kneading conditions. Is obtained.

[0029]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. still,
The measurements and tests of the physical properties in the examples were performed by the following methods. (1) Volume resistivity Using a φ100 × 3t flat plate test piece, the volume resistivity was measured in accordance with ASTM D257, and the average value of five test pieces was defined as the volume resistivity. In addition, the average of volume resistivity was calculated | required by logarithmic average. In addition, the measurement variation among the five test pieces was evaluated. (2) Tensile test Using ASTM No. 1 dumbbell specimen, in accordance with ASTM D638,
Tensile strength and tensile elongation were measured. (3) Bending test Using a bending test piece of 130 × 13 × 0.8 mm, the bending strength and the bending elastic modulus were measured in accordance with ASTM D790. (4) Fiber length measurement of carbon fiber 1 g of the pellet was heated to 500 ° C., and the carbon fiber remaining as ash (a mixture of graphite and glass fiber in some cases) was enlarged with a two-dimensional projector to reduce the carbon fiber number to 200. The measurement was performed as described above, and the weight average fiber length was determined. Examples 1 to 5 and Comparative Examples 1 to 7 For 100 parts by weight of a liquid crystalline polyester (LCP; Vectra A950, manufactured by Polyplastics Co., Ltd.), Table 1 was used.
Are dry-blended at the ratios shown in Table 1, and then twin-screw extruder (PCM-30, manufactured by Ikegai Iron Works Co., Ltd.)
The mixture was melt-kneaded in a mold and pelletized. The test piece was prepared from the pellet by an injection molding machine and evaluated, and the results shown in Table 1 were obtained.

[0030]

[Table 1]

CF; carbon fiber CF1; PAN type, diameter 7 μm, length 160 μm CF2; PAN type, diameter 7 μm, length 6 mm (chopped strand fiber) CF3; PAN type, diameter 7 μm, length 40 μm GP: graphite GP1 HAG-15 manufactured by Nippon Graphite Co., Ltd., artificial graphite,
Fixed carbon 98.5% by weight GP2; Nippon Graphite Co., Ltd. AOP, earth graphite, fixed carbon 93.0% by weight GF; chopped glass fiber, diameter 10μm, length 3mm

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F071 AA48 AB03 AD01 AF12 AF39 BA01 BB05 BC10 4J002 CF161 DA016 DA027 FA046 FD010

Claims (3)

[Claims] (1) PA liquid is added to 100 parts by weight of a liquid crystalline polymer (A).
A composition comprising 1 to 50 parts by weight of N-based carbon fiber (B), wherein the PAN-based carbon fiber (B) is dispersed in the composition at a weight average fiber length of 50 to 350 μm, and the volume resistivity is Is 1 × 10 ⁴ -1
× 10 ¹¹ Ω · cm, a semiconductive resin composition. 2. 100 parts by weight of the liquid crystalline polymer (A) is added to PA
1 to 50 parts by weight of N-based carbon fiber (B), 1 to 50 parts by weight of graphite (C) having 95% by weight or more of fixed carbon (however, the total amount of components (B) and (C) is 100 parts by weight of (A)) Of PAN-based carbon fiber (B) is dispersed in the composition at a weight average fiber length of 50 to 350 μm, and the volume resistivity is A semiconductive resin composition having a density of 1 × 10 ⁴ to 1 × 10 ¹¹ Ω · cm. 3. A molded article produced from the semiconductive resin composition according to claim 1.