JPH0333190B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electromagnetic wave shielding resin composition comprising a copolymer and carbon fiber, which has particularly good electromagnetic wave shielding effect and mechanical properties, and is excellent in flame retardancy. By adding a halogen-containing organic flame retardant, a flame retardant aid, and an ethylene-propylene terpolymer to an electromagnetic wave shielding resin composition consisting of a polymer and carbon fiber, the electromagnetic wave shielding effect, thermal properties, and mechanical properties are improved. The present invention relates to a resin composition having flame retardancy and excellent electromagnetic wave shielding properties. Conventionally, electronic devices such as office equipment, 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, aluminum die-casting, or the like, which has the ability to shield electromagnetic waves, and in this case, interference caused by 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;
Since plastic materials have almost no ability to shield electromagnetic waves, when using plastic materials for the housing of electronic devices, shielding treatment against electromagnetic waves is required. In particular, in recent years, strict restrictions have been placed on the radiation of electromagnetic waves from electronic devices both domestically and internationally, and there has been an increasing demand for electromagnetic wave shielding treatments for plastic materials. On the other hand, when plastic materials are used in the housings of these electronic devices, UL standards, CSA standards, etc. require that the plastic materials be made flame retardant in order to prevent accidents resulting in injury or death due to fire. Known methods for making plastic materials flame retardant include:
A flame retardant and a flame retardant aid are mixed with a flame retardant. Among the flame retardants, a halogen-containing organic flame retardant has a high flame-extinguishing effect, and when used in combination with a flame retardant aid such as antimony trioxide, Expected to be effective. Furthermore, methods of mixing chlorinated hydrocarbon resins such as vinyl chloride resin, chlorinated polyethylene resin, chlorinated polypropylene resin, and chlorosulfonated polyethylene resin are also widely known. However, in order to pass the normal flame retardant standards, such as the UL-94 vertical flame test,
Because it is necessary to add large amounts of these flame retardants, flame retardant aids, and chlorinated hydrocarbon resins, thermal properties,
It had poor mechanical properties. In particular, when a conductive filler such as carbon fiber is mixed into a resin in order to obtain a shielding effect against electromagnetic waves, mechanical properties such as impact strength are originally reduced, and the thermal conductivity of the resin is improved. As a result, the flame retardancy decreases, so it is necessary to add a large amount of flame retardant, flame retardant aid, and chlorinated hydrocarbon resin, and the thermal and mechanical properties of the molded product are completely inferior. It was hot. In view of the above-mentioned problems, the present inventors conducted intensive studies to solve the problem, and as a result, the present inventors developed a flame retardant material composed of a copolymer, carbon fiber, a halogen-containing organic flame retardant, and a flame retardant aid. By adding a small amount of ethylene-propylene terpolymer to the electromagnetic wave shielding resin composition, it has sufficient flame retardancy and molded products can be obtained by adding a small amount of halogen-containing organic flame retardant or flame retardant aid. The present invention was completed based on the novel finding that it is possible to obtain an electromagnetic wave shielding resin composition having good flame retardant thermal properties and mechanical properties. That is, the present invention provides: (1) an ethylenically unsaturated nitrile-diene rubber-aromatic vinyl copolymer or a mixture thereof with an ethylenically unsaturated nitrile-aromatic vinyl copolymer;
35 to 75% by weight (2) Ethylene-propylene terpolymer 2 to 20% by weight (3) Carbon fiber 5 to 40% by weight (4) Halogen-containing organic flame retardant 2 to 30% by weight (5) Flame retardant aid 0.4 to 40% by weight It is characterized by consisting of 18% by weight. The base resin of the flame-retardant electromagnetic wave shielding resin composition of the present invention is an ethylenically unsaturated nitrile-diene rubber-aromatic vinyl copolymer or an ethylenically unsaturated nitrile-aromatic vinyl copolymer with this copolymer. A mixture of The ethylenically unsaturated nitrile compound in the present invention includes, for example, acrylonitrile, methacrylonitrile, ethacrylonitrile, methylmethacrylonitrile, and the like, with acrylonitrile and methacrylonitrile being particularly preferred. The diene rubber in the present invention may be any one or more conjugated 1,3-dienes, such as butadiene, isoprene, 2-chloro-1,3-butadiene, 1-chloro-1,3-butadiene, piperylene, etc. Among rubber-like polymers, butadiene is particularly preferred. The aromatic vinyl compound in the present invention means styrene, a-methylstyrene, vinyltoluene, divinylbenzene, chlorostyrene, etc. alone or in a mixture. Among them, when styrene is used alone, in the case of the present invention, give better results. Furthermore, the ethylenically unsaturated nitrile-diene rubber-aromatic vinyl copolymer of the present invention includes 20 to 75 parts by weight of diene rubber or a diene-containing polymer containing 50% by weight or more of diene rubber, preferably 20 to 60 parts by weight.
A polymer having 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 grafted thereto is preferred. On the other hand, when using a mixture of ethylenically unsaturated nitrile-diene rubber-aromatic vinyl copolymer and ethylenically unsaturated nitrile-aromatic vinyl copolymer, the ratio is preferably 25 to 99 parts by weight of the former, preferably 35 parts by weight. ~65 parts by weight, preferably 1 to 75 parts by weight of the latter
A range of 65 to 35 parts by weight is good. Outside the above range,
Moldability and physical properties deteriorate. These manufacturing methods are disclosed in, for example, Japanese Patent Publication No. 37675/1983. Next, the ethylene-propylene terpolymer used in the present invention is an ethylene-propylene copolymer in which a small amount of unsaturated material having a double bond is introduced as a third component, and its composition is ethylene 50~ 80 mol%, propylene 20-50 mol%, unsaturates ranges from 0.5-10 mol%, but ethylene 60
~70mol%, propylene 30-40mol%, unsaturates
A range of 0.5 to 5 mol% is best. On the other hand, as the unsaturated substance, dienes or trienes are generally used, but 1,4 hexadiene, dicyclopentadiene, and ethylidene norbornene are particularly often used in view of their good copolymerizability and low cost. The amount of the ethylene-propylene terpolymer added is 2 to 20% by weight, preferably 5 to 10% by weight. If the amount added is less than 2% by weight, almost no flame retardant improvement effect is obtained, If the amount added exceeds 20% by weight, the mechanical and thermal properties of the molded article will be poor. Furthermore, if the amount added is significantly large, the flame retardancy, which is the objective of the present invention, will be impaired. Next, as the carbon fiber used in the present invention, one type or a mixture of two or more types selected from the group of polyacrylonitrile carbon fiber, pitch carbon fiber, and phenolic carbon fiber is used, and among them, polyacrylonitrile carbon fiber When used alone, a particularly good electromagnetic wave shielding effect can be obtained. The amount of carbon fiber added is 5 to 40% by weight, preferably 10 to 25% by weight. If the amount added is less than 5% by weight, almost no electromagnetic wave shielding effect can be obtained, and the amount added is less than 5% by weight.
If it exceeds 40% by weight, extrusion molding and injection molding will be difficult, and the mechanical properties of the molded product will be poor. Furthermore, the halogen-containing organic flame retardants used in the present invention include chlorinated paraffin, tetrabromobisphenol A and its oligomer, decabromobiphenyl ether, hexabromobiphenyl ether, pentabromobiphenyl ether, and pentabromotoluene. , pentabromoethylbenzene, hexabromobenzene, pentabromophenol, tribromophenol derivatives, perchloropentanecyclodecane, hexabromocyclododecane, tris-(2,3 dibromopropyl-1)-
Isocyanurates, tetrabromobisphenols and derivatives, 1,2 bis(2,3,4,5,6
-pentabromophenoxy)ethane, 1,2bis(2,4,6-tribromophenoxy)ethane,
Brominated styrene oligomer, 2,2-bis-(4
Examples include -(2,3,-dibromopropyl)-3,5 dibromophenoxy)propane, tetrachlorophthalic anhydride, and tetrabromophthalic anhydride. Flame retardant aids used in the present invention include antimony trioxide, sodium antimonate, zinc borate, zircon and molybdenum oxides and sulfides, with antimony trioxide giving the best results. The amount of the halogen-containing organic flame retardant added varies depending on the required degree of flame retardancy and the amount of ethylene-propylene terpolymer added, but is 2 to 30% by weight, preferably 5 to 25% by weight. If the amount of the halogen-containing organic flame retardant added is less than 2% by weight, a sufficient flame retardant effect cannot be obtained;
If it exceeds 30% by weight, the mechanical and thermal properties of the molded article will be poor. On the other hand, the amount of flame retardant aid added is 0.4 to 18% by weight.
Moreover, it is in the range of 6/10 to 2/10, preferably 5/10 to 3/10, of the halogen-containing organic flame retardant. If the amount of flame retardant auxiliary added is less than 0.4% by weight, the flame retardant effect due to the mutual effect with the flame retardant will not be sufficiently expressed, and if it exceeds 18% by weight, the mechanical properties of the molded article will be poor. Furthermore, if the amount added is less than 2/10 of the halogen-containing organic flame retardant, the flame retardant effect due to the mutual effect with the halogen-containing organic flame retardant will not be sufficiently expressed, and a sufficient flame retardant effect will not be obtained. If the amount added exceeds 6/10 of the halogen-containing organic flame retardant, the mechanical properties of the molded article will be poor. Furthermore, processing aids such as antioxidants, stabilizers, and lubricants may be added to improve the properties of the products of the present invention. Specifically, as the antioxidant, a phenolic antioxidant, a sulfur-based antioxidant, and a phosphorus-based antioxidant are used. The amount of antioxidant added is preferably 0.01 to 4 parts by weight per 100 parts by weight of the resin. As the stabilizer, metal soaps, inorganic acid salts, organic tin compounds, and composite stabilizers are used. The amount of stabilizer added is based on 100 parts by weight of resin.
0.01 to 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 per 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, an ethylenically unsaturated nitrile-diene rubber-aromatic vinyl copolymer in various shapes such as powder, beads, and pellets, or an ethylenically unsaturated nitrile-diene rubber-aromatic vinyl copolymer in various shapes, It consists of a mixture of saturated nitrile and an aromatic vinyl copolymer, as well as an ethylene-propylene terpolymer, carbon fiber, a flame retardant, and a flame retardant aid.
Diene rubber-aromatic vinyl copolymer is available in powder form,
It is more preferable to use the ethylenically unsaturated nitrile-aromatic vinyl copolymer in the form of beads. In order to make the composition of the present invention uniform, mixing and kneading is carried out in a kneader or extruder such as a Banbury mixer, co-kneader, single-screw extruder, or twin-screw extruder, and further, a kneader, Before mixing and kneading in an extruder, preliminary mixing may be performed using a means such as a tumbler or a high-speed mixer. The resin composition obtained by performing this mixing and kneading is
Injection using the resin composition of the present invention is performed by feeding the resin composition into the hopper of an injection molding machine, melting it in a plastic cylinder, injecting it into an injection mold, and taking out the molded product that has cooled and solidified in the mold. Similarly, the resin composition of the present invention can be obtained by feeding the resin composition into the hopper of an extrusion molding machine, melting it in the plasticizing cylinder, and extruding it from the die installed at the tip of the extruder. It is possible to obtain an extrusion molded product using a material. The present invention will be explained in more detail below with reference to Examples and Comparative Examples. Examples 1 to 8 As the resin, a powdered acrylonitrile-butadiene-styrene copolymer resin (ABB resin) having a composition ratio of 10% by weight of acrylonitrile, 50% by weight of polybutadiene, and 40% by weight of styrene, and 30% by weight of acrylonitrile and 70% by weight of styrene were used. Using bead-shaped acrylonitrile-styrene copolymer resin (AS resin) consisting of % by weight, ethylene-propylene-
As a terpolymer, ethylene-propylene-
Dicyclopentadiene resin, Mitsui Petrochemical Industries, Ltd.
The product name "EPT-#1045" was used. Next, the carbon fiber was a chopped strand of polyacrylonitrile carbon fiber manufactured by Toho Rayon Co., Ltd.
The halogen-containing organic flame retardant used was Tetrabromobisphenol A, the Teijin Kasei Co., Ltd. product name Fire Guard 2000 was used, and the flame retardant auxiliary agent was Nippon Mining Co., Ltd. Antimony trioxide manufactured by Co., Ltd. was used. Furthermore, 1 part by weight each of an antioxidant, a stabilizer consisting of tribasic lead, and zinc stearate were added to 100 parts by weight of the resin, and the composition was blended as shown in Table 1, and the mixture was heated at 140°C. The mixture was put into a Banbury mixer heated to 190℃ and melted and kneaded.
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 had a housing shape of 15 cm square with a thickness of 3 m/m, and the gate used was a direct gate with a diameter of 2 mmφ. The molded product obtained in this way has mechanical properties,
It was excellent in both heat resistance, flame retardancy, and electromagnetic wave shielding effect. Examples 9 to 11 The composition shown in Table 1 was pelletized in the same manner as in Example 1, and the pellets were fed into the hopper of an extruder with a diameter of 40 m/m (L/D = 24) and melted. The sample is then fed to a single layer sheet die at 200℃. The width of the die was adjusted to 600 m/m and the lip was adjusted to 3.5 m/m, resulting in a single layer sheet with a thickness of 3 m/m. As shown in Table 1, the obtained single-layer sheet had excellent mechanical properties, heat resistance, flame retardancy, and electromagnetic wave shielding effect. Examples 12-13 Instead of the powdered acrylonitrile-butadiene-styrene copolymer resin of Example 1, a powdered methacrylonitrile-butadiene-styrene copolymer resin consisting of 50% by weight of methacrylonitrile, 10% by weight of polybutadiene, and 40% by weight of styrene was used. A polymer resin (MBS resin) was used, and the composition other than that shown in Table 1 was pelletized in the same manner as in Example 1, and injection molded products were obtained using this pellet. As a result of measuring the physical properties, it was found to be excellent in mechanical properties, heat resistance, flame retardancy, and electromagnetic wave shielding effect. Example 14 Acrylonitrile 20% by weight, polybutadiene 20%
A pelletized acrylonitrile-butadiene-styrene copolymer resin (ABS resin) consisting of 60% by weight of styrene and 60% by weight of styrene was used, and the other compositions were as shown in Table 1, and the composition was pelletized in the same manner as in Example 1. An injection molded product was obtained using this. As a result of measuring the physical properties, the obtained molded product had mechanical strength,
It had excellent heat resistance, flame retardancy, and electromagnetic shielding effect. Examples 15 to 16 Instead of the ethylene-propylene-dicyclopentadiene resin in Example 1, ethylene-propylene-ethylidene norbornene resin, trade name "EPT-#3045" manufactured by Mitsui Petrochemical Industries, Ltd., was used, and others The compositions shown in Table 1 were pelletized in the same manner as in Example 1, and injection molded products were obtained using the pellets. As a result of measuring the physical properties, it was found to be excellent in mechanical strength, heat resistance, flame retardance, and electromagnetic wave shielding effect. Comparative Examples 1 to 2 Example 1 except that ethylene-propylene-dicyclopentadiene resin was added in an amount that did not reach the claimed range or exceeded the claimed range in the formulation shown in Table 2. An injection molded product was obtained in the same manner as above. Table 2 shows the results of measuring the physical properties of this injection molded product. Comparative Examples 3 to 4 Injection was carried out in the same manner as in Example 1, except that carbon fiber was added in an amount that was below the claimed range or in an amount that exceeded the claimed range, with the composition shown in Table 2. A molded product was obtained. Table 2 shows the results of measuring the physical properties of this injection molded product.

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[Table] The physical properties of the molded products shown in Examples and Comparative Examples are as follows:
Measurements were carried out by the following method. (1) Electromagnetic shielding effect: Using the Denka method to measure the electromagnetic 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 received through the sample and the transmitter are measured. The ratio to the voltage was measured using a spectrum analyzer. (2) Tensile strength: JIS K-6871 compliant (3) Bending strength, flexural modulus: ASTM D-790 compliant (4) Izot impact strength: JIS K-681 compliant (notched) (5) Thermal deformation Temperature: JIS K-7207 (load deflection temperature test of hard plastics) compliant method (6) UL-94 flame retardant test: UL-96 vertical combustion test compliant method (7) Oxygen index: JIS K-7201 compliant method

[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 (1)

[Scope of Claims] 1. Ethylenically unsaturated nitrile-diene rubber-aromatic vinyl copolymer or mixture thereof with ethylenically unsaturated nitrile-aromatic vinyl copolymer 35-
75% by weight 2. 2-20% by weight of ethylene-propylene terpolymer 3. 5-40% by weight of carbon fiber 4. 2-30% by weight of a halogen-containing organic flame retardant and 5. 0.4-18% by weight of a flame retardant aid. An electromagnetic wave shielding resin composition having flame retardancy, characterized by: