JPS626581B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an oil-resistant rubber composition having excellent resistance to rancidity and gasoline, and more specifically to an oil-resistant rubber composition containing butadiene and/or isoprene, acrylonitrile, and, if necessary, an α/β-monoethylenically unsaturated carboxylic acid ester and/or A copolymer rubber obtained by copolymerizing the carboxylic acid, a liquid polymer obtained by copolymerizing butadiene and/or isoprene, acrylonitrile, and α/β-monoethylenically unsaturated carboxylic acid, sulfur and The present invention relates to an oil-resistant rubber composition having excellent resistance to rancid gasoline and containing a vulcanizing agent comprising/or a sulfur donor and a specific p-phenylenediamine-based antiaging agent. Heat resistance, gasoline (oil) resistance, etc. have been improved due to engine improvements in line with passenger car exhaust gas regulations that have been implemented as a result of social demands to improve the air environment in recent years.
Many important safety parts made of synthetic rubber, which are both durable and cold resistant, are now being installed in passenger cars. Among existing synthetic rubbers, acrylonitrile-butadiene copolymer rubber (hereinafter sometimes referred to as NBR) is an excellent synthetic rubber with well-balanced properties and is used for applications such as hoses, gaskets, O-rings, and oil seals. Widely used. Furthermore, due to improvements in engines to comply with passenger car exhaust gas regulations, the atmosphere around the engine tends to be hotter than before, causing the problem of gasoline deterioration and rancid gasoline. By the way, although NBR has excellent gasoline resistance, it undergoes hardening deterioration when it comes into contact with deteriorated rancid gasoline, so there is a risk that parts installed in passenger cars made of NBR will not be able to maintain their functions over a long period of time. Contains. Therefore, an object of the present invention is to provide an oil-resistant rubber composition that prevents hardening type deterioration caused by rancid gasoline without sacrificing the heat resistance, gasoline (oil) resistance, and cold resistance possessed by NBR. It is in. This object of the present invention is to provide a copolymer rubber obtained by copolymerizing butadiene and/or isoprene, acrylonitrile, and optionally α/β-monoethylenically unsaturated carboxylic acid ester and/or the carboxylic acid; Butadiene and/or isoprene, acrylonitrile, and α-
A liquid polymer obtained by copolymerizing a β-monoethylenically unsaturated carboxylic acid, a vulcanizing agent consisting of sulfur and/or a sulfur donor, and a polymer having a solubility in n-hexane of 1 g/100 ml or less at 20°C. - Achieved by a composition containing a phenylenediamine anti-aging agent. That is, the present invention comprises 20-80% by weight of butadiene and/or isoprene, preferably 25-75% by weight, and 10-50% by weight of acrylonitrile, preferably
Copolymer rubber obtained by copolymerizing 15 to 45% by weight and α/β-monoethylenically unsaturated carboxylic acid ester and/or the carboxylic acid 0 to 60% by weight, preferably 0 to 50% by weight. 95 parts by weight, 30-80% by weight of butadiene and/or isoprene,
Preferably 40-75% by weight, acrylonitrile 10-
50% by weight, preferably 20-45% by weight and α/β
- 5 to 50 parts by weight of a liquid polymer consisting of 0.1 to 20% by weight of monoethylenically unsaturated carboxylic acid, preferably 0.5 to 15% by weight and having a number average molecular weight of 500 to 10,000, and sulfur and/or a sulfur donor; This objective is achieved by using a vulcanizing agent consisting of the following, and a p-phenylenediamine anti-aging agent having a solubility in n-hexane of 1 g/100 ml or less at 20°C. The copolymer rubber used in the present invention includes butadiene and/or isoprene, acrylonitrile,
and, if necessary, by copolymerizing α/β-monoethylenically unsaturated carboxylic acid ester and/or the carboxylic acid. Examples of α/β-monoethylenically unsaturated carboxylic acid esters include methyl acrylate, ethyl acrylate, n-propyl acrylate, and acrylic acid.
n-butyl, n-octyl acrylate, 2-ethylhexyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, 2-cyanoethyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, Examples include 2-ethylhexyl methacrylate,
Preferred are ethyl acrylate and n-butyl acrylate. Examples of α/β-monoethylenically unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, and maleic acid.
By copolymerizing α/β-monoethylenically unsaturated carboxylic acid ester and/or the carboxylic acid, the rancid gasoline resistance of NBR is improved, but when it exceeds 60%, cold resistance and compression set resistance and other physical properties are deteriorated, which is not preferable. The liquid polymer used in the present invention is obtained by copolymerizing butadiene and/or isoprene, acrylonitrile, and α/β-monoethylenically unsaturated carboxylic acid. Examples of the α/β-monoethylenically unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, and itaconic acid. The polymerization ratio is 0.1 to 20% by weight, and if it is less than 0.1% by weight, the rancid gasoline resistance will not be improved, and if it exceeds 20% by weight, other physical properties will deteriorate, which is not preferable. The copolymer rubber and liquid polymer in the present invention can be obtained by any polymerization method including emulsion polymerization, solution polymerization, suspension polymerization, and bulk polymerization, but emulsion polymerization is industrially advantageous and preferred. Further, the Mooney viscosity [ML ₁₊₄ , 100°C] of the copolymer rubber obtained by copolymerization is 10 to 150, preferably 30 to 80, and the number average molecular weight of the liquid polymer is 500 to 10,000. Yes, preferably 1000 to 5000. The rubber composition of the present invention consists of 50 to 95 parts by weight of copolymer rubber and 5 to 50 parts by weight of liquid polymer, but if the liquid polymer is less than 5 parts by weight, the rancid gasoline resistance will not be improved; Exceeding this is practically undesirable because the viscosity of the composition decreases and other physical properties are adversely affected. In order to achieve the object of the present invention, a sulfur-based vulcanizing agent must be blended with the copolymer rubber and liquid polymer for vulcanization. Like general NBR, the copolymer rubber and liquid polymer of the present invention can be peroxide vulcanized, but peroxide vulcanization must be avoided because they have poor rancidity gasoline resistance. The sulfur and/or sulfur donor used in the present invention may be a sulfur-based vulcanizing agent commonly used in NBR, and examples of the sulfur donor include morpholine disulfide, 2-(4-morpholinodithio)benzothiazole; Examples include thiuram compounds such as methylthiuram disulfide, tetraethylthiuram disulfide, and dipentamethylenethiuram tetrasulfide; alkylphenol disulfides, polymer polysulfides, and the like. The anti-aging agent used in the present invention is a p-phenylenediamine-based anti-aging agent having a solubility in n-hexane of 1 g/100 ml or less at 20°C. Preferably structural formula

[expression] or

[Formula] (wherein X is selected from the group consisting of phenyl, alkyl-substituted phenyl, and naphthyl groups, and Y is X or the following structural formula

【formula】

【formula】

【formula】

[Formula] and Z is The structural formula of

A group having the formula: R 1 to R ₅ are selected from the group consisting of hydrogen, alkyl having 1 to 4 carbon atoms, and alkoxy. ) is a p-phenylenediamine type anti-aging agent. Specifically, N・N′-diphenyl-p-phenylenediamine, N-phenyl-
N'-tolyl-p-phenylenediamine, N-phenyl-N'-β-naphthyl-p-phenylenediamine, N・N'-di-β-naphthyl-p-phenylenediamine, N-(4- anilinophenyl)
Acrylamide, N-(4-anilinophenyl)
Methacrylamide, N-(4-anilinophenyl)maleimide, 3-N-(4'-anilinophenyl)amino-2-hydroxypropyl allyl ether, 3-N-(4'-anilinophenyl)amino-2-hydroxypropyl acrylate, 3 -N
-(4'-anilinophenyl)amino-2-hydroxypropyl methacrylate, N-(p-anilinophenyl)-p-vinylbenzenesulfonamide, N-(2-propenylidene)-N'-phenyl-p-phenylenediamine, N -(2-methyl-
Examples include 2-propenylidene)-N'-phenyl-p-phenylenediamine, which may be used alone or in combination. Among these anti-aging agents, those having copolymerizability can be copolymerized and included in the copolymer rubber used in the present invention. To achieve the purpose of the present invention, p.
- Although a phenylenediamine antioxidant is an essential component, it is also possible to use other antioxidants within a range that does not impair rancidity gasoline resistance. The amount of p-phenylenediamine type anti-aging agent used in the present invention is based on the copolymer rubber and liquid polymer.
0.5 to 20 parts by weight per 100 parts by weight, preferably 1 to 20 parts by weight
It is 10 parts by weight. The oil-resistant rubber composition of the present invention is produced by copolymerizing butadiene and/or isoprene, acrylonitrile, and, if necessary, an α/β-unsaturated monoethylenically unsaturated carboxylic acid ester and/or the carboxylic acid. The obtained copolymer rubber,
A liquid polymer obtained by copolymerizing butadiene and/or isoprene, acrylonitrile, and α/β-monoethylenically unsaturated carboxylic acid;
a vulcanizing agent consisting of sulfur and/or a sulfur donor;
p-phenylenediamine anti-aging agent, and if necessary, ordinary rubber compounding agents such as vulcanization accelerators, vulcanization aids, reinforcing agents, fillers, plasticizers, and anti-aging agents, or NBR, etc. of rubber in a conventional mixer such as a roll or Banbury mixer. By heating this rubber composition, a rubber vulcanizate having excellent resistance to rancidity and gasoline can be obtained. The use of the present composition is not particularly limited, but since the vulcanizate has excellent resistance to rancidity and gasoline, it exhibits remarkable effects when used as an inner surface material for rubber hoses or diaphragms that come into contact with gasoline. In addition, various compounding agents are added and used together with rubber to the inner surface material of general rubber hoses.
Some components are dissolved in and extracted from gasoline, which poses a risk of clogging the fuel pump when installed in a passenger car.Surprisingly, however, the rubber vulcanizate obtained by the present invention does not dissolve in gasoline. It has low extractables and is particularly good as an inner material for fuel hoses. Next, the present invention will be specifically explained with reference to Examples. Example 1 The copolymer rubber and liquid polymer listed in Table 1 obtained by copolymerization using a known emulsion polymerization method were mixed with other compounding agents on a cooling roll according to the following formulation, and rubber compounding was carried out. obtained and heated it at 160℃ for 20
A vulcanizate was prepared by heating for a minute. The characteristics of the vulcanizate were measured in accordance with JIS K-6301. The rancid gasoline was prepared using commercially available regular gasoline in accordance with General Motors Corporation operating standards [OP-9308 (1966)] and was irradiated with ultraviolet rays intermittently for two weeks. The peroxide value of the resulting rancid gasoline was determined according to the Universal Oil Products Company test method (UOP test method 33-59) and was 24.1.
It was gram equivalent/1000. A 2 mm thick, 30 mm long, and 20 mm wide vulcanizate was soaked in this rancid gasoline, left for 72 hours in an atmosphere of 60°C, and vacuum dried at 60°C overnight. Evaluation was made by observation of occurrence. The above results are shown in Table 1. Mixing recipe (parts by weight) Mixture of copolymer rubber and liquid polymer (see Table 1) 100 Stearic acid 1 Zinc oxide 5 Sulfur 0.5 FEF Carbon black 40 SRF 〃 50 Di(butoxy-ethoxy-ethyl) adipate ( Plasticizer) ^*1 20 Tetramethylthiuram disulfide ^*2 2 Cyclohexylbenzothiazyl sulfenamide
^*3 1 N・N′-di-β-naphthyl-p-phenylenediamine ^*4 2 *1 Thiokol product Thiokol TP-95 *2 Ouchi Shinko Chemical Co. product Noxeler TT *3 〃 〃 CZ *4 〃 Nokratsuku
White

【table】

[Table] Example 2 The same test as in Example 1 was conducted on a butadiene-acrylonitrile-ethyl acrylate terpolymer rubber in which the weight percentage of acrylonitrile in the copolymer rubber was kept constant. The results are shown in Table 2.

[Table] Example 3 A terpolymer rubber containing 37% by weight of butadiene, 33% by weight of acrylonitrile, and 30% by weight of butyl acrylate was mixed with the liquid polymer shown in Table 3 according to the compounding recipe and vulcanization conditions of Example 1. The vulcanizate prepared according to the above was evaluated for rancidity gasoline resistance in the same manner as in Example 1. The results are shown in Table 3.

[Table] Example 4 Copolymer rubber containing 59% by weight of butadiene and 41% by weight of acrylonitrile (Nippol, a product of Nippon Zeon Co., Ltd.)
1041) Prepare a blended composition of 80 parts by weight and 20 parts by weight of the liquid polymer used in Example 1 on a cooling roll according to the blending recipe below, and pressurize and heat this at 160°C for a predetermined time. A vulcanizate was prepared and the following tests were conducted. The results are shown in Table 4.

【table】

【table】

[Table] Example 5 Copolymer rubber containing 59% by weight of butadiene and 41% by weight of acrylonitrile (Nippol, a product of Nippon Zeon Co., Ltd.)
1041) A mixture of 80 parts by weight and 20 parts by weight of the liquid polymer used in Example 1 was prepared on a cooling roll according to the following formulation, and by pressurizing and heating this at 160°C for 20 minutes. A vulcanizate was prepared and subjected to a rancid gasoline resistance test. The results are shown in Table 5. Mixing recipe (parts by weight) Mixture of copolymer rubber and liquid polymer 100 Stearic acid 1 Zinc oxide 5 Sulfur 0.5 FEF carbon black 40 Tetramethylthiuram disulfide 2 Cyclohexylbenzothiazyl sulfenamide
1 Anti-aging agent (see Table 5) 2

【table】

[Table] Example 6 Liquid polymer used in Example 1 in 80 parts by weight of terpolymer rubber of 31% by weight of butadiene, 33% by weight of acrylonitrile, and 36% by weight of n-butyl acrylate
Similar tests were conducted on a vulcanizate obtained using the same formulation as in Example 5, including 20 parts by weight. The results are shown in Table 6.

【table】

[Table] Example 7 Copolymer rubber containing 59% by weight of butadiene and 41% by weight of acrylonitrile (Nipol, a product of Nippon Zeon Co., Ltd.)
1041) Prepare a mixture of 80 parts by weight and 20 parts by weight of the liquid polymer used in Example 1 according to the following formulation, and then pressurize and heat at 155°C for 20 minutes to prepare a vulcanizate. Then, a rancid gasoline resistance test was conducted. In addition, the rancid gasoline resistance was determined using the method of Example 1, by immersing a JIS No. 3 dumbbell-shaped test piece (thickness 2 mm) in rancid gasoline at 60°C for 72 hours, then replacing the rancid gasoline and conducting the same immersion test. After repeating once more, a tensile test was conducted according to the immersion test of JIS K-6301. The results are shown in Table 7. Mixing recipe (parts by weight) Mixture of copolymer rubber and liquid polymer 100 Stearic acid 1 Zinc oxide 5 Sulfur 0.5 MAF Carbon 40 MT 〃 60 Di-(butoxy ethoxy ethyl) adipate
15 Tetramethylthiuram disulfide 2 Cyclohexylbenzothiazylsulfenamide
1 Anti-aging agent (see Table 7) 3

【table】

Claims (1)

[Claims] 1 (a) Butadiene and/or isoprene 20~
80% by weight, 50-95 parts by weight of copolymer rubber consisting of 10-50% by weight of acrylonitrile and 0-60% by weight of α/β-monoethylenically unsaturated carboxylic acid ester and/or said carboxylic acid, (b)butadiene and/or consisting of 30-80% by weight of isoprene, 10-50% by weight of acrylonitrile and 0.1-20% by weight of α/β-monoethylenically unsaturated carboxylic acid,
Liquid polymer 5 or more having a number average molecular weight of 500 to 10,000
50 parts by weight, (c) a vulcanizing agent consisting of sulfur and/or a sulfur donor, and (d) a p-phenylenediamine antioxidant having a solubility in n-hexane of 1 g/100 ml or less at 20°C. Oil-resistant rubber composition with excellent gasoline properties.