JPS6332094B2 - - Google Patents

Description

[Detailed description of the invention]

[] Purpose of the Invention The present invention is a resin composition comprising a styrene polymer, a chlorinated polyethylene rubber, and carbon black, and its purpose is to provide a resin composition with excellent conductivity. . [] Background of the Invention It has been widely known that thermoplastic resin compositions obtained by blending carbon black with thermoplastic resins have good electrical conductivity, and are widely used in practical applications. It's being used. However, the thermoplastic resin composition has significantly lower moldability and impact strength. Because of this, there are naturally limitations in terms of use, and various proposals have been made. Styrene homopolymers, styrene-based copolymers, and rubber-reinforced high-impact polystyrenes are highly rigid materials because their molecular chains are constrained by steric hindrance caused by phenyl groups. Furthermore, compared to crystalline olefin polymers such as propylene polymers and ethylene polymers, such styrene polymers have a smaller shrinkage rate during molding and have better dimensional accuracy, making them easier to machine. Widely used as parts, home appliance parts, etc. However, when a relatively large amount of carbon black is added to improve the conductivity of such styrenic polymers, the mechanical strength, especially the impact strength, decreases significantly compared to other thermoplastic resins. However, it was difficult to put it into practical use. [] Structure of the Invention Based on the above, the present inventors have searched various resin compositions containing styrene polymers with excellent conductivity, and have found that styrenic polymers, chlorinated polyethylene rubber materials, and carbon (A) The blending ratio of the styrene polymer is 40 to 89% by weight.
(B) The blending ratio of chlorinated polyethylene rubber is 5 to 30% by weight, and (C) The blending ratio of carbon black is 6 to 30% by weight.
It is. The present invention was achieved by discovering that the resin composition not only has good conductivity but also has the effects described below. [] Effects of the Invention The resin composition obtained by the present invention not only has excellent conductivity but also has the following characteristics (effects). (1) Excellent impact resistance. (2) Not only does it have good moldability, but it also has a low shrinkage rate during molding. (3) The dimensional accuracy of the molded product is excellent. As described above, the resin composition obtained by the present invention not only has good conductivity but also has the above-mentioned excellent characteristics, so it can be used in a wide variety of fields. Its uses are as follows. (1) Ordinary conductive material (2) Video disc (3) IC magazine (4) IC box [] Detailed description of the invention (A) Styrenic polymer The styrenic polymer used in the present invention is styrene alone. Polymers (generally with a molecular weight of 50,000 to 300,000), copolymers with other double-bonded organic compounds containing at least 10% by weight of styrene, and butadiene-based rubbers.
Examples include graft polymers obtained by graft polymerizing 99.5 to 80 parts by weight of styrene to 0.5 to 20 parts by weight. Representative examples of the organic compounds having double bonds include ethylene, vinyl acetate,
Mention may be made of maleic anhydride, acrylonitrile and methyl methacrylate. Methods for producing these styrenic polymers are widely known and are used in a wide variety of fields. (B) Chlorinated polyethylene rubber material The chlorinated polyethylene rubber material used in the present invention is obtained by chlorinating polyethylene powder or particles in an aqueous suspension, or by chlorinating polyethylene dissolved in an organic solvent. (preferably by chlorination in an aqueous suspension). Generally, it is amorphous or crystalline chlorinated polyethylene whose chlorine content is 20 to 50% by weight, especially chlorine content of 25% by weight.
~45% by weight of amorphous and crystalline chlorinated polyethylene is preferred. The polyethylene is obtained by homopolymerizing ethylene or copolymerizing ethylene with at most 10% by weight of α-olefin (generally having at most 6 carbon atoms). Its density is generally between 0.910 and 0.970/cc. Moreover, its molecular weight is 50,000 to 700,000. In producing the composition of the present invention, only chlorinated polyethylene may be used as the chlorinated polyethylene rubber material, but other types of rubber materials that are miscible with chlorinated polyethylene may also be blended. .
Examples of the rubbery material include ethylene-propylene-diene ternary copolymer rubber (EPDM), natural rubber, chloroprene rubber, chlorosulfonated polyethylene rubber, styrene-butadiene copolymer rubber (SBR), Examples include rubbery products such as acrylonitrile-butadiene copolymer rubber (NBR) and butadiene homopolymer rubber (generally having a Mooney viscosity (ML ₁₊₄ ) of 10 to 150). Regarding these rubber-like materials, see "Synthetic Rubber Handbook" edited by Kambara et al. (Asakura Shoten, published in 1962) and "Plastic Handbook" edited by Murahashi et al.
(published in 1964), etc., is well known. When these other types of rubbery materials are blended, their blending ratio is at most 50 parts by weight based on the chlorinated polyethylene. (C) Carbon black Furthermore, the carbon black used in the present invention generally has a specific surface area of 20 to 1800 m ² /g as measured by low-temperature nitrogen adsorption method and BET method.
The pore volume is 1.5 to 4.0 cc/g as measured by mercury porosimetry in a pore radius range of 30 to 7500 A°. Such carbon blacks include channel blacks, acetylene blacks, rubber distributed carbon blacks made by the furnace black process, and other conductive carbon blacks. Regarding these carbon blacks, please refer to "Carbon Black Handbook" edited by Carbon Black Association (Tosho Publishing Co., Ltd., published in 1972) and "Handbook of Rubber and Plastic Compound Chemicals" (Rubber Digest Co., Ltd., published in 1972), edited by Rubber Digest Co., Ltd. Their manufacturing methods and physical properties are well known, as described in the above-mentioned "Synthetic Rubber Handbook" published by J.D. Among these carbon blacks, conductive carbon black (generally has a specific surface area of 600 to 1200
m ² /g) is preferable because it has a large effect of imparting electrical conductivity to styrene polymers and can impart high electrical conductivity to styrene polymers with a relatively small amount. . (D) Blending ratio In the present invention, the blending ratio of the styrene polymer to the total amount of the styrene polymer, chlorinated polyethylene rubber, and carbon black is 40%.
-89% by weight, the proportion of chlorinated polyethylene rubber is 5-30% by weight, and the proportion of carbon black is 6-30% by weight.
In particular, the proportion of the styrene polymer in the total amount of these three materials is 55 to 80% by weight, the proportion of the chlorinated polyethylene rubber is 10 to 25% by weight, and the proportion of carbon black is 55 to 80% by weight. The blending ratio is 10
~20% by weight is desirable. If the blending ratio of the chlorinated polyethylene rubber is 5% by weight or less, a composition with excellent impact strength cannot be obtained, and furthermore, sufficient electrical conductivity (low surface resistance value) cannot be obtained.
In addition, the blending ratio of chlorinated polyethylene rubber material is
If it exceeds 30% by weight, there will be problems in terms of impact resistance and moldability. In addition, in the case where chlorinated polyethylene and the above-mentioned rubber-like material are used together as the chlorinated polyethylene-based rubber-like material in the present invention, the blending ratio of the chlorinated polyethylene-based rubber-like material is calculated as the sum of both. Further, it is desirable that the blending ratio of the chlorinated polyethylene rubber material to 100 parts by weight of the styrene polymer is at most 50 parts by weight. (E) Production and molding method of resin composition, etc. Although the composition of the present invention can be obtained by uniformly blending the above substances, fillers commonly used in the rubber industry and resin industry are also used. Additives such as plasticizers, oxygen, ozone, heat and light (ultraviolet) stabilizers, lubricants, and colorants may be added depending on the intended use of the composition. In addition, sulfur vulcanizing agents, sulfur-releasing compound-based vulcanizing agents, amine-based vulcanizing agents, organic peroxide-based crosslinking agents, and organic peroxide-based crosslinking coagents commonly used in the rubber industry and resin industry, etc. Additives may be added depending on the intended use of the composition. When producing the composition of the present invention, the blending (mixing) method may be to use a mixer commonly used in the art, such as an open roll, dry blender, Banbury mixer, and kneader. Among these mixing methods, in order to obtain a more uniform composition, two or more of these mixing methods may be applied (for example, after mixing in advance with a dry blender, the mixture may be mixed using an open roll). how to). In producing the composition of the present invention, all the ingredients may be mixed at the same time, but some of the ingredients may be mixed in advance and then other ingredients may be mixed into the resulting mixture ( For example, a method in which chlorinated polyethylene and styrenic polymer are mixed in advance, and then the resulting mixture is mixed with carbon black). The composition of the present invention may be molded into a desired shape using molding machines commonly used in the rubber industry, such as extrusion molding machines, injection molding machines, compression molding machines, and calender molding machines. In addition, a method of manufacturing a molded product by adding chlorinated polyethylene or the above-mentioned composition and vulcanizing (crosslinking) it in the rubber technology field, that is, a method of simultaneously proceeding vulcanization and molding, is applied. It may be formed into a desired shape. [] Examples and Comparative Examples The present invention will be explained in more detail below using Examples. In addition, in the Examples and Comparative Examples, Izod impact strength was measured according to JIS K6871. In addition, in the dimensional accuracy test, the dimensional stability was measured after hanging the product in a JIS type gear oven set at a temperature of 80°C for 1 hour, 24 hours, 48 hours, 72 hours, and 168 hours. Furthermore, the surface resistance value was measured using a sheet (thickness 1 mm) prepared using the method described below, and using an insulation resistance meter (manufactured by Takeda Riken Co., Ltd., trade name: Digital Meltimeter TR-6856) to measure the resistance of samples spaced at 1 cm intervals. I found the value. Examples 1 to 10, Comparative Examples 1 to 6 [(A) Production of chlorinated polyethylene] Polyethylene with a density of 0.950 g/cc (average molecular weight approximately 250,000) was chlorinated by an aqueous suspension method to reduce the chlorine content. A chlorinated polyethylene (amorphous, hereinafter referred to as "C1-PE(1)") containing 30.6% by weight was prepared. In addition, chlorinated polyethylene [amorphous, hereinafter referred to as "C1-PE(2)"] was prepared under the same conditions as C1-PE(1), except that it was chlorinated until the chlorine content was 35.2% by weight.
It was created. Styrene homopolymer with an average molecular weight of approximately 180,000 [hereinafter referred to as "PS(a)]" or styrene homopolymer with an average molecular weight of approximately 250,000 (hereinafter referred to as "PS(b)") as a styrenic polymer. Produced as a chlorinated polyethylene rubber-like product using (A) above,
C1-PE(1) or C1-PE(2) or C1-PE(1) and styrene-butadiene block copolymer rubber [Styrene content 25.0% by weight, Mooney viscosity (ML ₁₊₄ )
60, hereinafter referred to as "SBR"] was used. or,
As the carbon black, we used Ketuchen Black [manufactured by Lion Akzo, trade name: Ketuchen Black EC, density 1.8 g/cc, surface area 1195 m ² /g, hereinafter referred to as "C-1"], and other thermoplastic resins. Melt index (temperature 190℃,
Ethylene polymer (density 0.9 g/cc, hereinafter referred to as "PE") with a load of 2.16 kg/10 minutes, melt flow index (temperature of 230°C, load
2.16Kg) is 3.0g/10 minutes of propylene polymer (hereinafter referred to as "PP") or vinyl chloride polymer (average degree of polymerization approximately 650, hereinafter referred to as "PVC") in the amounts shown in Table 1. Mixed in advance for 10 minutes using a Henschel mixer. Each of the obtained mixtures was melt-kneaded using a kneader at 150 to 180°C to produce a mixture (composition). Each composition was kneaded using a mixing roll to create a sheet. In addition, after creating a pulverized product by pulverizing each of the obtained sheets, it is hot pressed at a temperature of 190°C under a pressure of 200Kg/cm ² (gauge pressure), and then subjected to Izotsu impact strength and dimensional accuracy. A test piece was prepared. The surface resistance value of each of the obtained sheets was measured, and the Izot impact strength and dimensional stability were also measured using each test piece. The results are shown in Table 2. Example 11, Comparative Example 7 Instead of C-1 used as carbon black in Example 1 and Comparative Example 1, carbon black with an average particle size of approximately
30 mm Furnace Black (manufactured by Cabot Inc., product name: Vulcan XC)
-72, density approximately 1.8g/cc, surface area 220m ² /g,
Mixing was carried out using a Henschel mixer under the same conditions as in Example 1, except that the mixture (hereinafter referred to as "C-2") was used. (The amount of each compounded is shown in Table 1). Each of the obtained mixtures was melt-kneaded in the same manner as in Example 1 to produce a composition. Each composition was kneaded to create a sheet. Further, each of the obtained sheets was crushed and then hot pressed under the same conditions as above to create each test piece. The obtained surface resistance values were measured, and Izot impact strength and dimensional stability were also measured using each test piece. The results are shown in Table 2.

【table】

【table】

[Table] From the above Examples and Comparative Examples, the resin composition obtained by the present invention contains a vinyl chloride polymer, an ethylene polymer, or a propylene polymer, a chlorinated polyethylene rubber, and carbon black. It is clear that these compositions not only have higher impact strength, but also have better surface resistance and dimensional accuracy than the respective compositions obtained by blending them. From the above-described advantages, it is clear that the resin composition obtained by the present invention is promising as a material for mechanical parts, household appliance parts, and the like.

Claims (1)

[Scope of Claims] 1. Consisting of a styrene polymer, a chlorinated polyethylene rubber material, and carbon black, (A) the blending ratio of the styrene polymer is 40 to 89% by weight, (B) chlorinated The blending ratio of polyethylene rubber is 5 to 30% by weight, and the blending ratio of (C) carbon black is 6 to 30% by weight.
It is. Resin composition.