JPS59166553A - Electroconductive resin composition - Google Patents

Abstract

PURPOSE:A composition that is obtained by combining a specific AS resin or a rubber-modified AS resin with an electroconductive substance, thus having high electroconductivity and improving its appearance of the formed product therefrom or of the coated product after forming, without any adverse effect on its impact strength. CONSTITUTION:(A) A rubber-modified thermoplastic resin which is prepared by polymerizing at least one selected from aromatic vinyl monomers and at least one selected from vinyl cyanides monomers, when necessary, at least one from other monomers copolymerizable with at least one of the above-cited monomers in the presence of a rubber-like polymer and/or a copolymer from the above- cited monomers, in which the content of vinyl cyanide components is 24-35wt%, preferably 28-35wt% in the fraction soluble in acetone in the thermoplastic resin, is combined with (B) an electroconductive substance so that its content is 3-25vol%.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conductive thermoplastic resin composition with improved impact resistance and appearance of molded articles.

Styrene-acrylonitrile resins or rubber-modified styrene-acrylonitrile resins have good impact resistance and surface appearance of molded products, and are easy to injection mold, allowing products with complex shapes to be obtained, so they have various functions as industrial materials. It is used as an external material for parts, automobile parts, and electrical products.

Especially in recent years, there has been an increase in design, weight reduction, and economy.

For example, dust adhesion due to static electricity, electrostatic coating methods used for metal products cannot be applied, and recently, various radio wave interferences occur due to insufficient electromagnetic shielding properties.

In particular, the I of circuit elements such as transistors and diodes, which are the driving force behind the miniaturization and weight reduction of current electronic components and devices, are
With the advancement of electronic circuit integration technology seen in the large-scale integration of C and IC, plastics have come to be used as the base material for these circuits, and there has been a demand for plastics to be made electrically conductive.

Styrene - Acrylonitrile resin Yacom modified styrene -
A conductive resin can be obtained by mixing acrylonitrile resin with a conductive material such as carbon black, carbon fiber, metal powder, metal fiber, metal flake, etc. However, on the other hand, the impact strength of the resin may decrease or the appearance of the injection molded product may be poor. Therefore, the commercial value decreases, and problems arise such as the appearance of the surface of the molded product becomes poor when painted.

On the other hand, the uses of resins have diversified, and depending on the use, flame retardant performance has come to be required of resins.

The object of the present invention is to provide a styrene-acrylonitrile resin that has good electrical conductivity, has an excellent surface appearance of a molded product without reducing impact strength, has an improved appearance after coating, and has excellent flame retardancy. Another object of the present invention is to provide a conductive resin composition comprising a rubber-modified styrene-acryloni resin.

In the resin composition comprising an electrically conductive substance and a thermoplastic resin according to the present invention, fAl the thermoplastic resin contains at least one aromatic vinyl monomer and a vinyl cyanide monomer in the presence of a rubbery polymer. A rubber-modified thermoplastic resin obtained by polymerizing at least one vinyl monomer and, if necessary, at least one other vinyl monomer copolymerizable with these monomers and/or the above-mentioned monomers. A copolymer, wherein the content of vinyl cyanide monomer units in the acetone dissolved content of the thermoplastic resin is 24 to 354.
There is provided a conductive resin composition characterized in that (B) the content of the conductive substance is 35% by weight and 3 to 25% by volume based on the total amount of the resin composition.

The thermoplastic resin (hereinafter referred to as component ~) used in the present invention is obtained by polymerizing a monomer mixture containing an aromatic vinyl compound and a vinyl cyanide compound as essential components in the presence or absence of a rubbery polymer. .

Examples of aromatic vinyl compounds include styrene, α-methylstyrene, vinyltoluene, P-methylstyrene,
Dimethylstyrene, bromstyrene and chlorus 11
It is particularly preferable to use styrene or a combination of styrene and α-methylstyrene. Examples of vinyl cyanide compounds include acrylonitrile and methacrylonitrile. Examples of vinyl compounds that can be copolymerized with these monomers include methacrylic esters such as methyl methacrylate and ethyl methacrylate, and acrylic esters such as methyl acrylate and ethyl acrylate. can be used singly or in combination of two or more.

The rubbery polymers used in the above component (A) include polybutadiene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, ethylene-propylene copolymer, and ethylene-propylene-dicyclopentadiene copolymer. and ethylene-propylene 12f IJ dennordelene copolymer, acrylic rubber, chlorinated polyethylene rubber, and the like.

The rubbery polymer content in the conductive resin composition of the present invention is 0.
-40% by weight, preferably 5-30% by weight.

The above component (A) can be obtained, for example, by an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method, or a solution polymerization method. Alternatively, blends of separately obtained polymers may be used as the component (-) provided that the composition of the composition is within the range defined by this invention.

The content of vinyl cyanide monomer units in the resin component (remaining part excluding the rubbery polymer) of the thermoplastic resin (A) is the vinyl cyanide content in the component (A) dissolved in acetone. The content is 24 to 35% by weight, preferably 28 to 35% by weight. On the other hand, from the viewpoint of resin strength and molding process, it is preferable that the intrinsic viscosity (30° C.) of the butanol-soluble portion of the resin component is 0.3 to 0.60 dt41r.

If the content of the vinyl cyanide monomer unit is less than 24% by weight, the surface smoothness of the molded product of the composition mixed with the conductive substance will be insufficient, resulting in poor appearance of the molded product and when the molded product is painted. This is not desirable because the painted appearance deteriorates.

In addition, thermoplastic resins containing rubbery polymers are not preferred because they have a large drop in impact strength when made into compositions.

On the other hand, if the weight of the lid exceeds 35, the moldability and color tone of the composition will deteriorate.

Although the method for producing component (A) is not particularly limited, for example, in the production of a rubber-containing thermoplastic resin, rubber-like polymer 1
In the presence of 0 to 60 parts by weight, 25 to 60 parts by weight of vinyl cyanide compound
There is a method of producing a thermoplastic resin by emulsion graft polymerization of 90 to 40 parts by weight of a monomer mixture consisting of 40 parts by weight and an aromatic vinyl compound of 75 = 60 parts by weight. Also, as a preferred method, (a) after polymerizing a monomer mixture containing 20% by weight or less of a vinyl cyanide compound in a proportion of 30% by weight or more of the total monomer mixture to be polymerized, (b) cyanizing. (e) Polymerize the remaining monomer mixture containing 35% by weight or more of the vinyl compound, and (e) adjust the content of vinyl cyanide units in the resin component of the obtained thermoplastic resin to 24 to 35% by weight. When the produced thermoplastic resin is used, better results can be obtained in appearance, chemical resistance, etc. of molded articles of compositions mixed with conductive substances than those produced by general polymerization methods.

The conductive substance (B) used in the present invention may be in the form of flakes. Types of carbon black used include channel black, furnaced black, and acetylene black.

These conductive substances can be used alone or in combination of two or more. The content of the conductive substance in the conductive composition of the present invention is 3 to 25 parts by volume, and less than 3 parts by volume with respect to the total amount of the conductive substance, thermoplastic resin, and additives such as flame retardants. The conductive resin composition targeted by the present invention cannot be obtained. On the other hand, if the volume exceeds 25, the conductive resin composition obtained will have poor moldability and poor surface appearance of the molded product, which is not preferred.

The volumes of the thermoplastic resin and conductive material of the present invention were determined by the following method.

When flame retardant performance is required for the conductive resin composition, a flame retardant is used. Examples of flame retardants include organic halodane compounds such as alicyclic halides, aromatic halides, phosphorus compounds, etc. Preferred flame retardants include hexabrom diphenyl ether, octabrom diphenyl ether, decafrom diphenyl ether, and tetrabrom diphenyl ether. Preferred are halogenated aromatic compounds such as oligomers of bromobisphenol A1, tetrabromobisphenol A, hexabromobenzene, and bis(bromoethyl ether)tetrabromobisphenol A.

Flame retardants can be used singly or in combination of two or more.

Further, a flame retardant synergistic effect agent can be used if necessary. Such flame retardant aids include antimony trioxide, sand,
One or more metal oxides such as metal oxide H7 (lium, zirconium oxide, etc.) can be used. Among these, antimony trioxide is particularly preferred.

The content of the flame retardant in the total amount of thermoplastic resin and flame retardant is 0 to 30% by weight, preferably 5 to 30% by weight.
It is a weight factor, and if it exceeds 30% by weight, the mechanical strength decreases, which is not preferable.

In addition, when using all the flame retardant synergistic effect agents, use less than 80 parts by weight of the flame retardant. Even if it exceeds 80% by weight, the flame retardant synergistic effect will reach an equilibrium and the mechanical strength will decrease, which is not preferable.

Mixing of the above components (A) and (B) and optionally a flame retardant and/or a flame retardant aid is carried out under known conditions using a commonly used roll, panburi mixer, extruder, etc. . As the extruder, it is preferable to use a twin-screw type extruder to obtain the product in the form of pellets.

During mixing, it is possible to use known stabilizers, plasticizers, mineral oils, dyes and pigments, fillers, or other thermoplastic resins such as polycarbinate and polyvinyl chloride in appropriate amounts.

Next, the present invention will be explained in more detail with reference to Examples.

In the following Examples and Comparative Examples, parts and units refer to parts by volume and weight unless otherwise noted.

The test methods described in Examples and Comparative Examples are shown below.

1. Acrylonitrile content ←); thermoplastic resin 2.
It shows the acrylonitrile content in the resin component mixed with 0 times the amount of acetone and dissolved in acetone.

Nitrogen was determined by Coleman analysis, and the amount of acrylonitrile was calculated from the amount of nitrogen.

2. Surface condition: Illuminate the surface of the injection molded plate with a fluorescent light and visually judge the degree of reflection (clarity) of the fluorescent light. The judgment criteria are as follows.

◎: Very good sharpness ○: Good Δ: Fairly bad ×: Bad 3 Volume resistivity: Silver paste was coated on the surface of an injection molded plate, and the measurement was performed at an applied voltage of 3V.

4. Flow tester with improved fluidity S (nozzle 11mφX
The flow rate was measured at 230° C. (2 mL, 30 Kg 1 arl pressure).

5. Izot impact strength: Tested using ASTM D-256 test piece thickness /4'' (notched).

This is an experimental example regarding a composition using As resin (acrylonitrile-styrene copolymer resin) as a thermoplastic resin and carbon black (Ketjen Black EC, Lion Exo Co., Ltd.) as a conductive material. Table 1 shows the properties, carbon black content, and physical properties of the composition using various As resins with different intrinsic viscosities.

Example 1 uses an As resin with an acrylonitrile content within the range of the present invention and shows the physical properties of a composition with a car block content within the range of the present invention. (13) (12) The target is obtained.

Experiment No. 6.7 of Comparative Example 1 was a case where carbon black was added in an amount outside the range of the present invention, and T&L6 had insufficient conductivity and Taki 7 had insufficient surface condition. Also Na8.
9 is an ASm whose acrylonitrile content is outside the range of the present invention.
In this example, ridge 8 indicates poor surface condition, and storm 9 indicates insufficient workability.

Example-2 Method for producing Niger raft polymer (I) [1st stage polymerization] Stirring device, heating jacket, reflux condenser, thermometer, nitrogen gas inlet, and continuous addition of monomer emulsion and polymerization initiator The following reagents were charged into a reaction vessel equipped with an apparatus, purged with nitrogen, heated, and graft polymerized at 70° C. for 1 hour.

Polybutadiene latex (as solid content) 40 parts by weight (Japan Synthetic: JSRO700 manufactured by M) Styrene
18 l acrylonitrile
2 parts by weight of disproportionated potassium rosin acid 1. o.

Terpinolene 0.027 cumenehydrono"-txy)' o, 10
[Dextrose 0.357 Sodium birophosphate 0.30# Ferrous sulfate] Iron 0. O]# Ion exchange water 15o [Second stage polymerization] Furthermore, the following mixture was continuously added over 2 hours.

Styrene 22 parts by weight Acrylonitrile 18 Cumene hydroperoxide 0.20 Terpinolene 0.20F After addition, the reaction was continued with stirring for an additional period of time. 2,6-
After adding 1.0 part of di-t-butyl para-cresol,
Sulfuric acid (2 parts per 100 parts of polymer) was added to solidify the mixture]5). This was separated, washed with water, dehydrated, and dried to obtain a graft copolymer (I) in which the resin component (acetone-soluble portion) excluding the rubbery polymer had an acrylonitrile content of 31%.

Using this thermoplastic resin, according to the method of Example-1,
The experiments shown in Table 2 were conducted.

Experimental floor of Example-2] 0 to 17 are experimental examples in which various conductive substances were applied in varying amounts within the scope of the present invention to a thermoplastic resin obtained by mixing the above-mentioned graft copolymer and A S resin. Therefore, the object of the present invention has been obtained.

Comparative Example-2 Example of manufacturing method for Nicraft polymers (II) and (■)-
Graft polymers (IT) and (III) were produced in the same manner as in Example 2, except that the amounts of styrene and acrylonitrile used were changed to the following amounts. Ta.

(16) Second stage polymerization unit 'fA'c4; Styrene Acrylonitrile = 29/11 (parts by weight) Second stage polymerization unit i1: /< + L/N/acrylonitrile = 23/17 parts by weight The acrylonitrile content of the graft polymer (II) obtained was 19%, and the acrylonitrile content of the graft polymer (m) was 41%.

The graft polymer (n) was blended with the As resin used in Example 1 with an acrylonitrile content of 28% under the conditions shown in Table 2, and a thermoplastic resin with an acrylonitrile content of 21.3% outside the scope of the present invention was obtained. (Experimental magnet 18). On the other hand, the graft polymer (III) was blended with the A8 resin with an acrylonitrile content of 32% used in Example 1 to obtain a thermoplastic resin with an acrylonitrile content of 39% outside the range of the present invention (Experiment No. 19).

The physical properties of these thermoplastic resin and carbon black compositions are shown in Table 2.

Comparative example outside the acrylonitrile content range of the present invention -
No. 2 does not provide a molded product with an excellent surface condition.

Example-3: The graft polymer of Example-2 was produced in exactly the same manner as in Example-2, except that the amount of rubber charged and the lubricant were changed to the following composition. A kraft polymer (I) with an acrylonitrile content of 32%, a graft polymer (V) with an acrylonitrile content of $31%, and a kraft polymer (Vl) with an acrylonitrile content of 32% were obtained (experiments h20-25). The physical properties of the composition of this graft polymer and conductive substance are shown in Table 2. A composition aimed at by the present invention was obtained.

[1st stage polymerization] Polybutadiene latex (as solid content) 24 parts by weight (Japan Synthetic Rubber Co., Ltd. squared! JSRO700) Styrene 18 parts by weight Acrylonitrile 9 # [2nd stage polymerization] Styrene 33 N acrylonitrile 16 [1] Stage polymerization] Polyphtadiene latex (as solid content) 24 parts by weight (JSRO700) Styrene 16N acrylonitrile 9I Methyl meccrylate
2 [Second-stage polymerization] Styrene 28N acrylonitrile ]6 [Methyl methacrylate]
51 [1st stage polymerization] Polybutadiene 24 (JSRO700 manufactured by Japan Synthetic Rubber Co., Ltd.) Styrene 2
4 Acrylonitrile 2.6 [Second stage polymerization] Styrene 27 Acrylonitrile 22.4 Example 4 An example of a conductive resin composition imparted with flame retardancy is shown.

The following flame retardant was added to the conductive resin composition of the experimental part 22 of Example 2, and a prototype was evaluated to obtain a conductive resin composition imparted with flame retardancy.

Experiment No. 26 in the above table is a conductive resin composition of the present invention to which no flame retardant is added, and is shown to prove the flame retardant effect of Experiments No. 27 and 28 in the same table.

Claims (1)

[Scope of Claims] A resin composition comprising an electrically conductive substance and a thermoplastic resin, wherein (A) the thermoplastic resin is combined with at least one aromatic vinyl monomer in the presence of a rubbery polymer; A rubber-modified thermoplastic resin obtained by polymerizing at least one vinyl cyanide monomer and, if necessary, at least one other vinyl monomer copolymerizable with these monomers, and/or the above-mentioned rubber-modified thermoplastic resin. A copolymer consisting of monomers, wherein the content of vinyl cyanide monomer units in the acetone-soluble portion of the thermoplastic resin is 24 to 35% by weight, and (B) the total amount of the resin composition. An electrically conductive resin composition characterized in that the content of the electrically conductive substance is 3 to 25 volumes relative to the electrically conductive substance.