KR910009864B1 - High intensity conductive resin composition - Google Patents

Abstract

The resin compsn. comprises (A) 40-98 wt. pts. of the resin comprising (A) 40-98 wt.% of the resin comprising 0.5-35 wt. pts. of epoxy resin of formula (I) with 100 wt. pts. of the styrenic resin; and (B) 2-60 wt. pts. of carbon fiber. The styrenic resin comprises; 5-95 wt. pts. of the graft copolymer (A-1) prepd. by polymerizing one or more monomer selected from aromatic monoalkenyl monomer, vinyl cyanide monomer, alkyl ester monomer of (meth)acrylic acid, maleic acid anhydride monomer or N-substd. maleimide monomer, and dienic rubber component or alkylacrylate rubber component; and 95-5 wt. pts. of the copolymer prepd. by copolymerizing the said monomers.

Description

High Rigidity Conductive Resin Composition

The present invention relates to a conductive resin composition excellent in rigidity.

Recently, as the demand and frequency of use of electric and electronic devices have explosively increased, there is a growing interest in the malfunction of devices caused by electromagnetic interference, which did not occur when using metal exterior materials.

This phenomenon occurs due to the fact that the external materials do not shield the electromagnetic waves generated during the operation of the device because most of the external materials of the electronic and electronic devices are replaced with plastics, and the generated electromagnetic waves pass through the external materials and interfere with the electromagnetic waves during operation of other devices. .

Already developed countries such as the US, West Germany and Japan have regulated the shielding ability of most electric and electronic devices for many years to prevent malfunction caused by electromagnetic interference. .

On the other hand, since plastics are not conductive, they do not discharge by themselves when static electricity is generated, which causes great damage to electronic components such as semiconductors or circuits during instantaneous discharge of charged static electricity.

In order to prevent such malfunctions and damages caused by electromagnetic interference and electrostatic discharge, a method of providing conductivity of the exterior member has been studied in recent years. Currently, a method of coating a conductive material on the inner surface of the exterior member is most widely used. However, this coating method is not permanent, and also has many problems in processing, so recently, a method using a conductive composite material which is permanent by giving a conductivity by mixing a conductive material in the plastic itself and requiring little secondary processing has been developed. It is becoming.

The conductive composite material has an advantage of controlling conductivity according to the amount of the conductive filler to be prepared by mixing a fibrous, flake or particulate material composed mainly of metal or carbon.

Carbon fiber, which is one of the fillers of the conductive composite material, has been widely used because of its relatively low specific gravity, easy processing, and reinforcing rigidity of the resin.

However, since the adhesive force between resin and carbon fiber is not good depending on resin used, there is little rigid reinforcement effect.

In particular, styrene-based alloy resins containing styrene-based resins and styrene-based resins, such as ABS resins, have almost no adhesion to carbon fibers.

The present inventors have endeavored to reinforce such existing disadvantages, and as a result, have completed the present invention showing excellent rigidity while maintaining conductivity.

The composition of the present invention will be described in detail as follows.

The highly rigid conductive resin composition of the present invention comprises at least one monomer selected from (A) an aromatic mono alkenyl monomer, a vinyl cyan monomer, an alkyl ester monomer of acrylic acid or methacrylic acid, a maleic anhydride monomer and an N-substituted maleimide monomer. Graft copolymer (A-1) prepared by polymerizing with diene rubber component or alkyl acrylate rubber component, aromatic mono alkenyl monomer, vinyl cyan monomer, acrylic acid or methacrylic acid monomer, maleic anhydride monomer, N-substituted maleic acid Resin 40 to which the copolymer (A-2) copolymerized with at least one monomer selected from the mid monomers is composed of 0.5 to 35 parts by weight of epoxy resin based on 100 parts by weight of the styrene base resin having a weight ratio of 5:95 to 95: 5. It is a resin composition characterized by including 98 weight part and (B) 2-60 weight part of carbon fibers.

Hereinafter, the present invention will be described in more detail.

The graft copolymer (A-1), which is a styrene-based basic resin according to the present invention, may be prepared using a bulk polymerization, suspension polymerization, emulsion polymerization, or a mixture polymerization thereof, and among these polymerization methods, emulsion polymerization may be employed. For example,

That is, the rubber component is first polymerized to prepare a rubber component polymer latex, and then to an aromatic mono alkenyl monomer, vinyl cyan monomer, acrylic acid or methacrylic acid based on 3 to 70% by weight, preferably 5 to 60% by weight of the rubber component. 30 to 97% by weight, preferably 40 to 95% by weight of one or more monomers selected from alkyl ester monomers, maleic anhydride monomers and N-substituted maleimide compounds are added to the graft by emulsion polymerization in the presence of a small amount of emulsifier. Copolymer (A-1) can be manufactured. Rubber components used in the graft copolymers include butadiene rubbers, isoprene rubbers, copolymers of butadiene and styrene monomers and alkyl acrylate rubbers, and the particle diameter thereof is 0.1 to 15 µm, preferably 0.2 to 5 µm. to be.

Moreover, as a monomer component, styrene, (alpha) -methylstyrene, P-methylstyrene, acrylonitrile, methacrylic acid methyl ester, methacrylic acid ethyl ester, acrylic acid methyl ester, maleic anhydride, N-phenylmaleimide, etc. are each The composition ratio of the components is added to the rubber-based polymer latex, and can be arbitrarily adjusted by controlling the content of the monomers.

The copolymer (A-2), which is another basic resin of the composition of the present invention, is prepared by a bulk, suspension, emulsion polymerization, or a mixed polymerization method thereof, like the component (A-1), and the monomer component (A-1). Is the same as the monomer component.

The graft copolymer (A-1) and the copolymer (A-2) thus prepared are mixed and used in a weight ratio of 5:95 to 95: 5, preferably 15:85 to 85:15, according to the present invention. The base resin of the highly rigid, conductive resin composition is constituted.

The composition may be replaced with a resin based on the styrene resin as the main component of the styrene resin, if necessary, the resin alloyed with polycarbonate resin, polyphenyl ether resin, etc., and acrylonitrile-butadiene rubber, ethylene -Propylene-diene rubber etc. can be added.

Epoxy resin as the component (B) of the present invention is a bisphenol-based compound represented by the following general formula (I), a novolac-based compound represented by the general formula (II), and other special agents as an adhesion promoter to enhance the adhesion between the carbon fiber and the basic resin. All epoxy resins such as epoxy resins can be used.

(In said formula (I), X is alkyl or sulfur and n is an integer of 0 or more.)

(In said formula (II), Y is alkyl or hydrogen and m is an integer of 0 or more.)

The amount used is 0.5 to 35 parts by weight based on 100 parts by weight of the basic resin, preferably 2 to 30 parts by weight. If this component is used at 0.5 parts by weight or less, the rigid reinforcing effect cannot be expected, and when it is used at 34 parts by weight or more, undesirable phenomena such as impact strength decrease and crosslinking reaction may occur, and thus the balance of the physical properties of the resin cannot be achieved. .

Carbon fiber which is (B) component of this invention can use both a high rigid fiber and a high elastic modulus fiber, and is 2 to 60 weight% as a chopped fiber of 3-6 mm in length.

When the component (B) of the present invention is used in an amount of 2 wt% or less, the conductive effect of the resin composition cannot be expected, and when used in an amount of 60 wt% or more, the fluidity is greatly reduced, and the impact strength is severely reduced, thereby achieving balance of physical properties. it's difficult.

The resin composition according to the present invention as described above is characterized by having improved rigidity while maintaining the conductivity according to the carbon fiber addition amount.

The invention is explained in detail in the following examples.

Example 1

It consists of 3 parts by weight of epoxy resin (Luck product: LER 4050) based on 100 parts by weight of a base resin composed of 80 parts by weight of ABS resin (Lucky product: ABS HI 100) and 20 parts by weight of SAN resin (Lucky product: SAN 80HF). After the resin composition was uniformly mixed with a Henschel mixer, pellets were prepared by adding carbon fibers (T005-006 manufactured by Toray Industries, Inc.) in an extruder (Swiss Booth MDK-40). At this time, the resin was introduced into a powder feeder, and the carbon fiber was added so as to be 20% by weight of the final product using a filler feeder separately.

After drying the obtained pellets at 80 ° C. for 2 hours, a test specimen for physical properties and a sample for measuring conductivity were injection molded using a 2.5-ounce injection machine.

Physical properties measured tensile strength and elongation according to ASTM D638, flexural strength and modulus according to ASTM D790, and impact strength according to ASTM D256.

Conductivity is expressed as volume resistivity by measuring the resistance of the specimen. For volume resistivity, cut both ends of the specimen of thickness (3mm) × width (12.5mm) × length (125mm) by 5mm, apply it with a temperature material, dry it, and measure the resistance of the specimen with a resistance measuring instrument. Calculated.

Where R is the volume specific resistance (Ω · Cm) l is the specimen length (Cm) A is the area (cm 2) ρ of the electrode coated with the thermal material and the electrical resistance (Ω) is shown in Table 1 It was.

Example 2

Except that 10% by weight of the carbon fiber in the composition of Example 1 was tested in the same manner as in Example 1 and the results are shown in Table 1.

Comparative Example 1

Except that no epoxy in the composition of Example 1 was tested in the same manner as in Example 1 and the results are shown in Table 1.

Comparative Example 2

Except that no epoxy was used in the composition of Example 2 was tested in the same manner as in Example 1 and the results are shown in Table 1.

TABLE 1

As shown in Table 1, it can be seen that the use of epoxy resin significantly improves the tensile strength and flexural strength.

Claims (4)

One or more monomers selected from aromatic mono alkenyl monomers, vinyl cyan monomers, alkyl ester monomers of acrylic acid or methacrylic acid, maleic anhydride monomers and N-substituted maleimide monomers are polymerized with a diene rubber component or an alkyl acrylate rubber component. A copolymer obtained by copolymerizing the prepared graft copolymer (A-1) with at least one monomer selected from an aromatic mono alkenyl monomer, vinyl cyan monomer, acrylic acid or methacrylic acid monomer, maleic anhydride monomer, and N-substituted maleimide monomer. 40 to 98 parts by weight of resin comprising 0.5 to 35 parts by weight of epoxy resin relative to 100 parts by weight of (A) styrene-based resin having a weight ratio of 5:95 to 95: 5 and (B) 2 to 5 carbon fibers. Resin composition characterized in that composed of 60 parts by weight. The composition according to claim 1, wherein the epoxy resin is a compound represented by the following general formula (I).

[Wherein X in the general formula (I) is alkyl or sulfur and n is an integer of 0 or more. The resin composition according to claim 1, wherein the epoxy resin is a compound represented by the following general formula (II).

[In Formula (II), Y is alkyl or hydrogen, and m is an integer of 0 or more.] The resin composition according to claim 1, wherein the carbon fibers are 3-6 mm chopped fibers.