JPS6123629A - Resin composition having electromagnetic wave shielding ability - Google Patents

Abstract

PURPOSE:To obtain a resin composition having a good effect of electromagnetic wave shielding and excellent impact strength, by adding a coupling agent to a mixture of a specified copolymer and carbon fiber. CONSTITUTION:A resin composition comprising 57-90wt% ethylenically unsaturated nitrile/diene rubber/aromatic vinyl copolymer or its mixture containing an ethylenically unsaturated nitrile/aromatic vinyl copolymer, 3-25wt% plasticizer, 5-40wt% carbon fiber and 0.2-5wt% coupling agent. As the ethylenically unsaturated nitrile compound used, acrylonitrile or methacrylonitrile is particularly desirable. As the diene rubber, butadiene rubber is particularly desirable. As the aromatic vinyl compound, styrene can be used with good results.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides a resin composition comprising a copolymer, carbon fiber, a plasticizer, and a coupling agent.
The present invention relates to a resin composition that has good electromagnetic wave shielding properties and excellent mechanical properties such as impact strength.

The resin composition provided by the present invention is used for the casing of electronic equipment such as office equipment, electronic computers, and TV receiver-1.

(Prior Art) Conventionally, electronic devices such as office equipment, electronic computers, and TV receivers have themselves been sources of electromagnetic waves, causing malfunctions and noise in surrounding electronic devices.

On the other hand, these electronic devices are affected by electrical devices installed nearby, and may malfunction or generate noise themselves.

The housings of these electronic devices are made of sheet metal, die-cast aluminum, or the like, which has the ability to shield electromagnetic waves, and in this case, interference due to electromagnetic waves can be prevented to some extent.

However, in recent years, plastic materials have been widely used for the housings of electronic devices due to their advantages such as ease of molding, flexible design, and light weight.

Plastic materials generally have poor conductivity and have almost no ability to shield electromagnetic waves, so when plastic materials are used in the housing of electronic devices, shielding treatment for electromagnetic waves is required.

In particular, recently, strict restrictions have been placed on the radiation of TA waves from electronic devices, both domestically and internationally, and there is an increasing demand for electromagnetic wave shielding treatments for plastic materials.

Conventional methods for imparting electromagnetic shielding effects to plastic materials include: ■ Laminating aluminum foil or conductive tape, ■ Zinc spraying, ■ Coating conductive paint, ■ Plastic plating, ■ Vacuum deposition, sputtering, A number of methods are being considered, including ion silating, (1) molding with conductive plastic mixed with conductive filler, etc.

■ The method of applying electromagnetic wave shielding effect by laminating aluminum foil or conductive tape requires skill.
It has many drawbacks, such as not being suitable for complex shapes, and is rarely used these days.

■ Zinc thermal spraying and ■ coating with conductive paints are commonly used methods, but with complex shapes, the film thickness becomes uneven and the adhesion to the base material is uneven. However, if the conductive layer peels off, the electromagnetic wave shielding effect may be lost and there may be a risk of fire.

■ Plastic plating has good durability and adhesion, but the types of plastic that can be used as base materials are limited, and furthermore, its application is limited to small products.

■Vacuum evaporation, sputtering, ion blating, etc. can achieve good electromagnetic shielding effects by applying metal evaporation technology, but the equipment is expensive and advanced technology is required, so commercial production is almost impossible. It is not done often.

In contrast to the above-mentioned method of forming a conductive layer on the surface of a plastic molded product and imparting an electromagnetic wave shielding effect, 1. Molding of conductive plastic by dispersing and compounding conductive fissies in glass. There is no concern that the electromagnetic wave shielding effect will deteriorate due to peeling of the conductive layer or that there will be a risk of fire.

However, such conductive plastic molded products are
If multiple conductive fillers are not added, the electromagnetic wave shielding effect will not be completely diminished, and increasing the amount added may impair the mechanical properties of the base plastic or result in a poor appearance.
Furthermore, it has the disadvantage of being extremely expensive.

In particular, when the amount of conductive filler increases, its uniform dispersibility with the resin deteriorates, the shielding effect decreases due to the cutting of fibers during cross-wire, and the viscosity of the resin composition increases, making moldability difficult and increasing the amount of dust. There were disadvantages such as a decrease in the physical properties of the molded product due to resin deterioration due to an increase in melting temperature, a decrease in the physical properties of the molded product, especially impact resistance strength, due to insufficient wetting of the resin to carbon fibers, and poor coloring properties.

(Problems to be Solved by the Invention) The present invention aims to solve these drawbacks, and by adding a coupling agent to a mixture of the copolymer, carbon fiber, and plasticizer, Uniform dispersion with fibers,
In addition, there is almost no cutting of fibers, and the fluidity of the resin composition is improved, resulting in good moldability and the melting temperature not being raised more than necessary, resulting in a significant decrease in physical properties and poor appearance due to resin deterioration. Furthermore, since the resin sufficiently wets the carbon fibers, it is possible to provide a resin composition that has good physical properties of molded articles, particularly good impact strength, and has electromagnetic wave shielding properties.

(Means for solving the problem, that is, the present invention is directed to the use of a t1+ -z ethylene unsaturated nitrile-dienedemu aromatic vinyl copolymer or an ethylenically unsaturated nitrile-aromatic vinyl copolymer thereof). 57-90% by weight of a mixture with (2) 6-25% by weight of a plasticizer, (3) 5-40% by weight of carbon fiber, and (4) 0.2-5% by weight of a coupling agent. It is a resin composition with properties.

The base resin of the electromagnetic wave shielding resin composition of the present invention is an ethylenically unsaturated nitrile rubber-aromatic vinyl copolymer or an ethylenically unsaturated nitrile-aromatic vinyl copolymer. A mixture of is used.

Examples of the ethylenically unsaturated nitrile compound in the present invention include acrylonitrile, methacrylonitrile, ethacrylonitrile, and methylmethacrylonitrile, with acrylonitrile and hismethacrylonitrile being particularly preferred.

The diene rubber in the present invention includes one or more conjugated 1,6-dienes, such as butadiene, isoprene,
2-chloro-1,6-citadiene, 1-chloro-1,3
- Any rubbery polymer such as butadiene, piperylene, etc., but sitadiene is particularly preferred.

The aromatic vinyl compounds in the present invention include styrene, α
- Means methylstyrene, vinyltoluene, divinylbenzene, chlorostyrene, etc. alone or in mixtures, among which styrene alone gives better results in the present invention.

Furthermore, the ethylenically unsaturated nitrile-diene rubber-aromatic vinyl copolymer of the present invention is a diene rubber or a diene-containing polymer 2 containing 50% by weight or more of a diene rubber.
A good polymer is a polymer in which 80 to 25 parts by weight, preferably 80 to 40 parts by weight of a mixture of an ethylenically unsaturated nitrile compound and an aromatic vinyl compound is grafted to 0 to 75 parts by weight, preferably 20 to 60 parts by weight.

On the other hand, when a mixture of ethylenically unsaturated nitrile-diene rubber-aromatic vinyl copolymer and ethylenically unsaturated nitrile-aromatic vinyl copolymer is used, the ratio of the former is 25 to 99 parts by weight, preferably 65 to 65 parts by weight,
The latter is preferably in a range of 1 to 75 parts by weight, preferably 65 to 65 parts by weight.

Outside the above range, moldability and physical properties deteriorate.

These manufacturing methods are described, for example, in Japanese Patent Publication No. 37675/1983. The amount of the copolymer or mixture thereof added is from 57 to 90% by weight, and outside this range, moldability and physical properties deteriorate.

Next, the plasticizers used in the present invention are, specifically, dibutyl phthalate, dibutyl phthalate, di-2-ethylhexyl 7-talate, dibutyl phthalate, di-2-ethylhexyl adipate, di-2-ethylhexyl adipate, etc. , dibutyl sepacate, di-2-ethylhexyl sepacate, di-2-ethylhexyl azelate, epoxidized fatty acid monoester, epoxidized soybean oil,
Epoxidized linseed oil, phosphoric acid esters include tricresyl phosphate, tri-2-ethylhexyl phosphate, and triptoxyethyl phosphate; ether-based compounds include triethylene glycol di-2-ethyl butyrate and dibutyl Carbitol adipate, dibutyl calketol formal, polyesters include adipic acid polyester, sepecic acid polyester,
Azelaic acid polyester and chlorine-based plasticizers include chlorinated aliphatic esters, chlorinated paraffins, etc. .

The amount of plasticizer added is 3 to 25% by weight, preferably 5 to 1% by weight.
5% by weight, and if the amount added is less than 6% by weight, the melt viscosity of the resin at the time of wire crossing is high, so the fiber length is cut short, poor dispersion occurs, the shielding effect decreases, and the viscosity increases. This makes moldability difficult. If it exceeds 25% by weight, the mechanical properties and heat resistance will deteriorate, and the molded product will become sticky due to plasticizer bleeding.

Furthermore, the carbon fiber used in the present invention is one type or a mixture of two or more selected from the group of polyacrylonitrile carbon fiber, Gitsuchi carbon fiber, and phenolic carbon fiber. Among them, polyacrylonitrile carbon fiber is used. Particularly good electromagnetic wave shielding effects can be obtained when the fibers are used alone.

The amount of carbon fiber added is 5 to 40% by weight, preferably 10% by weight.
~25% by weight, and if the amount added is less than 5% by weight, almost no electromagnetic wave shielding effect will be obtained, and if the amount added exceeds 40% by weight, it will be difficult to perform extrusion molding or injection molding, and furthermore, the molded product will be difficult to form. The mechanical properties are inferior. The coupling agent used in the present invention is A. Examples of the silane coupling agent include γ-chlorozolopyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, and vinyltris(β-methoxyethoxy). Silane, γ-methacryloxypropyltrimethoxysilane, β-(3,4-
epoxycyclohexyl)ethyltrimethoxysilane,
γ-glycypropyltrimethoxysilane, γ-mercaptozolopyltrimethoxysilane, γ-aminozolopyltriethoxysilane, N-β-(aminoethyl)-
γ-Aminonorobyltrimethoxysilane, γ-ureidopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane. Titanate coupling agents include isopropyl triisostearoyl titanate, isopropyl tridecylbenzenesulfonyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, tetraisopropyl bis (dioctyl phosphite) titanate, and tetraoctyl bis (ditridecyl phosphite). Titanate, tetra(2,2-diallyloxymethyl-1
- One type, or a mixture of two or more selected from the group consisting of butyl) bis(di-tridecyl) phosphite titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, tris(dioctyl pyro7 osphate) ethylene titanate, aluminum-based coupling agent, etc. Let's use it.

In particular, when a silane-based coupling agent is used as a coupling agent, a resin composition with particularly high mechanical properties such as impact strength can be obtained. - When trimethoxysilane is used, a resin composition with the best mechanical properties such as impact strength can be obtained.

The amount of the coupling agent added is 0.2 to 5% by weight, preferably 0.5 to 6% by weight, and the amount added is 0.2 wt.
If it is less than %, there will be no improvement effect on mechanical properties such as impact strength, and if it exceeds 5-fold air accumulation, the oxygen index will be low due to F.
Not only does the flame retardance deteriorate, but also the mechanical properties such as impact strength become inferior.

Furthermore, processing aids such as antioxidants, stabilizers, and lubricants may be added to improve the performance of the products of the present invention.

Details (c. As an antioxidant, phenolic antioxidant,
Sulfur-based antioxidants and phosphorus-based antioxidants are used.

The amount of antioxidant added to the bone is 0.0% per 1 DO weight part of the resin.
01 to 4 parts by weight is preferred.

As the stabilizer, metal soaps, inorganic acid salts, organic tin compounds, and composite stabilizers are used.

The amount of stabilizer added is 0.01 parts by weight per 100 parts by weight of resin.
~4 parts by weight is preferred.

As lubricants, paraffin and hydrocarbon resins, fatty acids,
Fatty acid amides, fatty acid esters, fatty alcohols, and partial esters of fatty acids and polyhydric alcohols are used.

The amount of lubricant added is 0.01 to 100 parts by weight of resin.
4 parts by weight is preferred.

Next, in the method for producing the resin composition of the present invention, first, powdery
Ethylenically unsaturated nitrile-diene rubber-aromatic vinyl copolymers in various shapes such as beads and pellets, or mixtures of this with ethylenically unsaturated 2) IJ sil-aromatic vinyl copolymers in various shapes, and further plasticized However, from the viewpoint of moldability and physical properties of the molded product, the powder form of the ethylenically unsaturated nitrile-diene rubber-aromatic vinyl copolymer is It is more preferable to use beads in the coalescence. In addition, in order to make the composition of the present invention uniform, mixing and mixing are performed in a mixer or extruder such as a Banbury mixer, a co-kneader, a single-screw extruder, or a twin-screw press ratio machine. Tumbler before mixing in the machine or extruder.
The premixing may be performed using any means such as the one-hole speed mixer 7c.

The resin composition obtained by performing this mixing and cross-mixing is supplied into the hopper of an injection molding machine, melted in a plasticizing cylinder, injected into an injection mold, and cooled and solidified in the mold to produce a molded product. By taking out the resin composition of the present invention, an injection molded product can be obtained.Similarly, the resin composition is fed into the hopper of an extrusion molding machine, melted in a bath in a plasticizing cylinder, and extruded. By extruding through a die installed at the tip of the machine, an extrusion molded product using the resin composition of the present invention can be obtained.

(Example) The present invention will be explained in detail below with reference to Examples.

Examples 1 to 8 As the resin, the composition ratio is acrylonitrile 10% by weight,
Powdered acrylonitrile loosetadiene consisting of 50% by weight of polybutadiene and 40% by weight of styrene - styrene copolymer resin (ABS resin) supported by 60% by weight of acrylonitrile
A bead-shaped acrylonitrile-styrene copolymer resin (As resin) consisting of 40% styrene by weight was used, and the plasticizer was di-2-ethylhexyl phthalate-based Kako Soap Co., Ltd.
The product name is "Vinicysa-≠80", and the carbon fiber is a chopped strand of polyacrylonitrile carbon fiber manufactured by Toho Rayon Co., Ltd., product name [Besphite HTAC6S J].
The coupling agent was γ-glycidoxypropyl, a silane-based coupling agent, and the mixture was put into a Banbury mixer heated to 4o'c and melted and kneaded until the mixture was 190% When the temperature reached ℃, it was taken out, immediately cooled into a sheet shape using a mixing roll, and crushed into pellets.

The pellets are fed into the hopper of an 8 ounce injection molding machine, melted in a plasticizing cylinder, and injected into an injection mold.

The injection mold has a casing shape of 15mm square with a thickness of 3mm.
A direct rotor with a diameter of 2 mm was used as the date.

The molded product thus obtained was excellent in mechanical properties such as impact strength, heat resistance, and electromagnetic wave shielding effect.

Examples 9 to 11 The compositions shown in Table 1 were pelletized in the same manner as in Example 1, and pelletized using an extruder (diameter 40W LA'n) (r
, /b=24) into a hopper and melted in a bath of 200
Feed into a single layer sheet die at °C.

Die width is 6001n/m, lip is 3.5FX
/F7! As a result, a single layer sheet with a thickness of 3 ml and 1 m was obtained.

As shown in Table 1, the obtained single-layer sheet had excellent mechanical properties such as impact strength, heat resistance, and electromagnetic wave shielding effect.

Examples 12 to 16 Instead of the powdered acrylonitrile-butadiene-styrene copolymer resin of Example 1, 50% of methacrylonitrile, 10% of polybutashev, and 40it% of styrene were used.
A powdered methacrylonitrile-butadiene-styrene copolymer resin (MBS resin) consisting of the following composition was pelletized in the same manner as in Example 1, and the other compositions were as shown in Table 1. I got the item. As a result of measuring the physical properties, it was found to be excellent in mechanical properties such as impact strength, heat resistance, and electromagnetic wave shielding effect.

Example 14 A pelletized acrylonitrile-detadiene-styrene copolymer resin (ABS resin) consisting of 20% by weight of acrylonitrile, 20% by weight of polybutadiene, and 20% by weight of methane was used, and the other formulations were as shown in Table 1. The composition was pelletized in the same manner as in Example 1, and an injection molded product was obtained using the pellet.

As a result of measuring the physical properties, it was found to be excellent in mechanical properties such as impact strength, heat resistance, and electromagnetic wave shielding effect.

Example 15 A composition using isopropyl triisostearoyl titanate instead of γ-glycidoxyprogyltrimethoxysilane in Example 1, and the other formulations shown in Table 1 was pelletized in the same manner as in Example 1. This was used to obtain an injection molded product.

As a result of measuring the physical properties, it was found to be excellent in mechanical properties such as impact strength, heat resistance, and electromagnetic wave shielding effect.

Comparative Examples 1 to 2 Injection was carried out in the same manner as in Example 1, except that the composition as shown in Table 2 was used and a plasticizer was added in an amount that did not reach the claimed range or exceeded the claimed range. A molded product was obtained.

Table 2 shows the results of measuring the physical properties of this injection molded product.

Comparative Examples 3 to 4 The same method as in Example 1 except that carbon fiber was added in an amount less than the claimed range or in excess of the claimed range in the blending composition shown in @2 table. An injection molded product was obtained.

Table 2 shows the results of measuring the physical properties of this injection molded product.

Comparative Examples 5 to 6 The same method as in Example 1, except that the composition was as shown in Table 2, and the coupling agent was added in an amount that was below the claimed range or in an amount that exceeded the claimed range. An injection molded product was obtained.

The results of measuring the physical properties of this injection molded product are shown in Table 2.

The physical properties of the molded products shown in the Examples and Comparative Examples were measured by the following method.

(1) Electromagnetic wave shielding effect: Using the Denka method to measure the electromagnetic wave shielding effect shown in the drawing, a high-frequency voltage excited by a tracking generator is applied to the transmitting antenna, and the received voltage and the transmitted voltage received through the sample are The ratio was measured using a spectrum analyzer.

(2) Tensile strength: JIS K-6871 compliant method (
3) Bending strength, bending modulus ASTM D-790
Conception method (4) Izot impact strength: , rrs K
-6871 compliant method (with notch) (5) Vicat softening temperature 2 JIS K-7206 compliant method (6) Oxygen index: JIS K-7201 compliant method (
Effects of the Invention) The present invention provides a resin composition consisting of a copolymer, carbon fibers, a plasticizer, and a coupling agent, which has good electromagnetic shielding properties and sufficient elasticity of the resin against carbon fibers. It has excellent moldability and also exhibits excellent effects on mechanical properties such as impact strength of molded products.

[Brief explanation of the drawing]

The drawing is a schematic diagram of an apparatus for measuring the electromagnetic wave shielding effect of a plastic molded body according to the present invention. Code 1... Shield box, 2... Plastic molded product, 3... Transmitting antenna, 4... Receiving antenna, 5
...Spectrum Analyzer, 6...Tracking Generator

Claims (4)

[Claims] (1) Ethylenically unsaturated nitrile-diene rubber-aromatic vinyl copolymer or a mixture of this and ethylenically unsaturated nitrile-aromatic vinyl copolymer 57 to 90% by weight (2) Plasticizer 3-25% by weight (3) Carbon fiber 5-40% by weight (4) A resin composition having electromagnetic wave shielding properties characterized by comprising 0.2 to 5% by weight of a coupling agent.