JPS6133862B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a rubbery copolymer composition with excellent oil resistance and heat resistance. More specifically, specific compounding agents for a specific rubbery terpolymer consisting of (a) butadiene, (b) an α/β-unsaturated nitrile compound, and (c) an α/β-unsaturated carboxylic acid ester are described. The purpose is to provide a copolymer composition which is excellent in heat resistance and has a well-balanced oil resistance and cold resistance. Conventionally, various oil-resistant rubbers have been used as rubbers that are highly resistant to oil, gasoline, solvents, and the like. Among them, NBR is the most commonly used rubber because it has excellent oil resistance, cold resistance, and workability during processing, but other oil-resistant rubbers ( For example, hydrin rubber, acrylic rubber, fluoro rubber)
The biggest drawback was that it was inferior in heat resistance compared to . In recent years, automobile exhaust gas regulations have become stricter.
Each automobile manufacturer is developing their own countermeasures, and as part of these measures, there has been a demand for a rubber that has oil resistance and cold resistance comparable to NBR, as well as excellent heat resistance. An object of the present invention is to provide a rubbery copolymer composition that satisfies these demands. As a result of various studies for the above purpose, the present inventors found that
A specific compounding agent is blended with a specific rubbery terpolymer consisting of (a) butadiene, (b) an α/β-unsaturated nitrile compound, and (c) an α/β-unsaturated carboxylic acid ester. The vulcanized composition has the same oil resistance and cold resistance as NBR, and at the same time
The present invention was achieved by discovering that the heat resistance, which had been considered a drawback of NBR, was significantly improved. That is, the present invention provides: (a) (b) Butadiene 10% by weight or more and less than 50% by weight (b) α/β-unsaturated nitrile compound
10% by weight or more and less than 40% by weight (c) α/β-unsaturated carboxylic acid ester
Rubber-like terpolymer consisting of 10% by weight or more and less than 80% by weight 100 parts by weight (b) Inorganic filler 20 - 400 parts by weight (c) Vulcanizing agent 0.1 - 5 parts by weight (d) Vulcanization aid 0.1 - 5 parts by weight (e) Anti-aging agent consisting of a combination of aromatic amine and mercaptobenzimidazole or N-alkyl-substituted dithiocarbamic acid
0.5 to 5 parts by weight (f) and other rubber additives in appropriate amounts are blended and vulcanized to provide a copolymer composition. The content of butadiene in the rubbery terpolymer affects the heat resistance, and if it exceeds 50% by weight, the heat resistance will not be sufficiently developed. On the other hand, in order to improve sulfur vulcanizability and cold resistance, the content should be 10% by weight or more. Therefore, the content of butadiene is 10% by weight or more and less than 50% by weight. Examples of the α/β-unsaturated nitrile compound include acrylonitrile and methacrylonitrile, with acrylonitrile being particularly preferred. α・β-unsaturated carboxylic acid ester has the general formula [R ₁ is hydrogen or a methyl group, R ₂ is an alkyl group having 1 to 12 carbon atoms]. Specific examples include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, and n-acrylate.
n-hexyl, n-octyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, 2-methoxyethyl acrylate, methyl methacrylate, n-butyl methacrylate, n-octyl methacrylate, Examples include 2-ethylhexyl methacrylate and n-dodecyl methacrylate. Among these, preferred are methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, ethyl methacrylate, and n-methacrylate.
-butyl, 2-ethylhexyl methacrylate, and n-butyl acrylate is particularly preferred. The preferred composition range of the rubbery terpolymer is: (a) Butadiene 20-40% by weight (b) α/β-unsaturated nitrile compound 15-30% by weight (c) α/β-unsaturated carboxylic acid ester
A rubbery terpolymer having the above composition in which the component (b) is acrylonitrile and the component (c) is n-butyl acrylate is particularly preferred. The method of polymerizing the rubbery terpolymer used in the present invention is not particularly limited, and may be any of emulsion polymerization, suspension polymerization, solution polymerization, and bulk polymerization, but emulsion polymerization is particularly preferred. The Mooney viscosity (ML ₁₊₄ , ₁₀₀ ° C.) of the rubbery polymer obtained by polymerization is about 30-90. The inorganic fillers used in the present invention include commonly used carbon black, white carbon, calcium carbonate, white glaze, titanium white, etc., and these can also be used in combination. The amount used is 20 to 400 parts by weight per 100 parts by weight of the rubbery terpolymer, but 40 to 100 parts by weight is usually preferred. Sulfur is preferred as the vulcanizing agent used in the present invention. Oil-resistant rubbers (hydrin rubber, acrylic rubber, fluoro rubber, etc.) that have better heat resistance than NBR are not sulfur-cured like NBR, but the composition of the present invention can be sulfur-cured under the same conditions as NBR. It can be obtained by sulfurization, so it is general.
This is practically advantageous. The amount of the vulcanizing agent used is 0.1 to 5 parts by weight, preferably 0.1 to 0.5 parts by weight, per 100 parts by weight of the rubbery terpolymer. The vulcanization aid used in the present invention is preferably a sulfenamide type (for example, JIS-K6215CZ) or a thiuram type (for example, JIS-K6206TT). The amount of the vulcanization aid used is 0.1 to 5 parts by weight, preferably 1 to 5 parts by weight, per 100 parts by weight of the rubbery terpolymer. The anti-aging agents used in the present invention include aromatic amines, which are peroxide-inactive anti-aging agents (d), and mercacaptobenzimidazoles or N-alkyl-substituted dithiocarbamic acids, which are secondary anti-aging agents (e). A combination is preferred. As the aromatic amine, compounds represented by the following general formula can be used. [ _R1 is phenyl or naphthyl group, _R2 is H or alkyl group] Preferred aromatic amines are phenyl-β-naphthylamine or alkylated diphenylamine,
Especially octylated diphenylamine. Mercaptobenzimidazoles are represented by the following general formula. [R ₁ is H or CH ₃ , M is H or a metal of the periodic table or group, preferably Ni and
Zn, n is 1 or 2] The N-alkyl-substituted dithiocarbamic acids are salts of hydrogen or metals of Groups 1, 2, and 2 of the periodic table, and preferred among these are salts of metals of groups 1, 2, and 2 of the periodic table. Preferred examples include Zn and Ni salts.
It is expressed by the following general formula. [R ₁ and R ₂ are alkyl groups having 1 to 8 carbon atoms, preferably alkyl groups having 1 to 4 carbon atoms] The above compounds are used in combination at a ratio of (d)/(e) = 5/1 to 1/5. In this case, excellent anti-aging effects can be obtained. Particularly preferable combination ratio is (d)/(e)=3/1~
It is 1/3. The amount of the antiaging agent consisting of a combination of aromatic amine and mercaptobenzimidazole or N-alkyl-substituted dithiocarbamic acid is 0.5 to 5 parts by weight, preferably 1 to 3 parts by weight per 100 parts by weight of the rubbery terpolymer. Department. Other rubber additives are not particularly limited, but include zinc white, stearic acid, plasticizers, etc., which are commonly used for rubber, and appropriate amounts thereof are used. The composition of the present invention includes the above-mentioned rubbery terpolymer (a), an inorganic filler (b), a vulcanizing agent (c), a vulcanization aid (d),
An anti-aging agent (e) consisting of a combination of an aromatic amine and a mercaptobenzimidazole or an N-alkyl-substituted dithiocarbamic acid and other rubber additives (f) are added and mixed well using a mixer such as a roll or Banbury mixer. It is manufactured by vulcanization using a vulcanization press, vulcanization pot, etc. Next, the present invention will be explained with examples. The physical properties were measured according to the following method. (i) Tensile test - JIS K6301-3 (ii) Hardness test - JIS K6301-5 JIS A type (iii) Aging test - JIS K6301-6 Test tube heating aging test Test conditions are temperature 150℃ for hours
70 hours (iv) Oil resistance test - JIS K6301-12, volume change of No. 1 oil and No. 3 oil was tested. Conditions were 120°C, 70 hours (v) Cold resistance test - JIS K6301-14 impact zeification test Compositional analysis was determined from elemental analysis values (carbon, nitrogen). In addition, parts and percentages in the following examples are by weight unless otherwise specified. Examples 1 to 4 Butadiene, α/β-unsaturated nitrile compound,
The copolymerization recipe and polymerization conditions of the α/β-unsaturated carboxylic acid ester were as follows. Water 180 parts Butadiene 23 Acrylonitrile 23 Ethyl acrylate 54 Disproportionated rosin acid potassium salt 4.5 Potassium phosphate 0.3 Ferrous sulfate 0.005 Paramenthane hydroperoxide 0.02 t-dodecyl mercaptan 0.1-0.5 (variable) Polymerization temperature 30 °C Conversion rate 70 % When a predetermined conversion rate was reached, 0.5 part of sodium dimethyldithiocarbamate was added as a polymerization terminator to terminate the polymerization. Next, an anti-aging agent shown in Table 2 was added, unreacted monomers were removed by steam distillation, and calcium chloride was added to precipitate a polymer. The precipitated polymer was washed with water and dried at 100°C for 1.5 hours. The Mooney viscosity (ML ₁₊₄ , ₁₀₀ °C) of the copolymer and the monomer composition ratio in the copolymer are as follows. Mooney viscosity (ML ₁₊₄ , ₁₀₀ ℃) 53.5 Amount of bound AN (%) 24.3 Amount of bound BD (〃) 26.9 Amount of bound EA (〃) 48.8 Octylated diphenylamine and phenyl-β-
Naphthylamine was emulsified in advance with fatty acid soap and added to the latex. Mercaptobenzimidazole or dimethyldithiocarbamic acid-Ni was added at the time of formulation. The formulation for physical property evaluation is as follows. Polymer 100 parts Zinc white 5 Stearic acid 1 HAF carbon black 50 Sulfur 0.3 TT 2.0 CZ 2.0 Vulcanized for 20 minutes in a heated press at 160°C to obtain a vulcanized product. Table 1 shows the physical properties of the vulcanizate. Comparative Examples 1 and 2 The anti-aging agents shown in Table 1 were added to the rubbery terpolymer polymerized by the method of Example 1. The addition method was carried out in accordance with Example 1. The physical property evaluation method was performed in accordance with Example 1. The physical properties of the vulcanizate are shown in Table-
Shown in 1. Comparative Examples 3 to 6 Using commercially available NBR (NBR N231L manufactured by Nihon Gosei Rubber Co., Ltd.), the anti-aging agent shown in Table 1 was added using the addition method of Example 1. The physical property evaluation method was performed in accordance with Example 1.
The physical properties of the vulcanizate are shown in Table-1. Examples 1, 2, 3, and 4 have much better heat resistance than Comparative Examples 1 and 2. Furthermore, compared to Comparative Examples 3 and 4, the heat resistance of Comparative Examples 5 and 6 was not improved much. From this result, the anti-aging agent system containing octylated diphenylamine or phenyl-β-naphthylamine and mercaptobenzimidazole or nickel dimethyldithiocarbamate is
Although NBR does not have a significant effect on improving heat resistance, it is clear that the composition of the present invention is very effective. Comparative Example 7 A copolymer was prepared by replacing butadiene with isoprene as shown in Table 2, and the physical properties of the vulcanizate were measured. The results are shown in Table 2, and the copolymer composition obtained by replacing butadiene with isoprene has poor cold resistance and also has a large decrease in strength (ΔT _B ) in heat resistance. Therefore, the present invention using butadiene is superior to using isoprene.

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Claims (1)

[Claims] 1 (a) (a) Butadiene 10% by weight or more and less than 50% by weight (b) α/β-unsaturated nitrile compound
10% by weight or more and less than 40% by weight (c) α/β-unsaturated carboxylic acid ester
100 parts by weight of a rubbery terpolymer consisting of 10% by weight or more and less than 80% by weight (b) Inorganic filler 20 - 400 parts by weight (c) Vulcanizing agent 0.1 - 5 parts by weight (d) Vulcanization aid 0.1 to 5 parts by weight (e) Anti-aging agent consisting of a combination of aromatic amine and mercaptobenzimidazole or N-alkyl-substituted dithiocarbamic acid.
A copolymer composition prepared by blending an appropriate amount of 0.5 to 5 parts by weight (f) and other rubber additives and vulcanizing the mixture. 2. The copolymer composition according to claim 1, wherein the α/β-unsaturated nitrile compound is acrylonitrile. 3 α/β-unsaturated carboxylic acid ester is methyl acrylate, ethyl acrylate, acrylic acid-
The copolymer composition according to claim 1, which is n-butyl, 2-ethyl-hexyl acrylate, ethyl methacrylate, n-butyl methacrylate or 2-ethyl-hexyl methacrylate. 4 The composition of the rubbery terpolymer is (a) butadiene 20-40% by weight (b) α/β-unsaturated nitrile compound 15-30% by weight (c) α/β-unsaturated carboxylic acid ester
30 to 60% by weight of the copolymer composition according to claim 1. 5. The copolymer composition according to claim 1, wherein the inorganic filler is carbon black, white carbon, calcium carbonate, white glaze, or titanium white. 6. The copolymer composition according to claim 1, which contains 0.1 to 0.5 parts by weight of sulfur as a vulcanizing agent. 7. The copolymer composition according to claim 1, wherein the aromatic amine is alkylated diphenylamine or phenyl-β-naphthylamine. 8. The copolymer composition according to claim 7, wherein the aromatic amine is octylated diphenylamine. 9. Claim 1, wherein the mercaptobenzoylimidazoles are mercaptobenzimidazole, Ni salt or Zn salt of mercaptobenzimidazole, methyl-mercaptobenzimidazole, or Ni salt or Zn salt of methyl-mercaptobenzimidazole. copolymer composition. 10 N-alkyl-substituted dithiocarbamic acids are diethyldithiocarbamic acid, Zn salt or Ni salt of diethyldithiocarbamic acid, or di-n-
Butyl-dithiocarbamic acid, di-n-butyl-
The copolymer composition according to claim 1, which is a Zn salt or Ni salt of dithiocarbamic acid. 11 The anti-aging agent is octylated diphenylamine and mercaptobenzimidazole, phenyl-β-naphthylamine and mercaptobenzimidal, octylated diphenylamine and di-n-butyl-dithiocarbamic acid Ni salt, or phenyl-β-naphthylamine and di-n- The copolymer composition according to claim 1, which is a combination of butyl-dithiocarbamic acid Ni salt.