JP2007161869A - Sealant vulcanization molding ethylene-alkylacrylate copolymer rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an AEM rubber composition which does not cause a trouble such as air mixing, is improved in the rubber strength and oil resistance of vulcanized moldings made from an AEM material, and can be vulcanized and molded into a seal material that is suitably used as a piston seal for a transmission base automatic gearbox. <P>SOLUTION: The ethylene-alkylacrylate copolymer rubber composition comprises 100 wt.pts. of a ternary ethylene-acrylate copolymer rubber having an amine vulcanizable group, 0.5-15 wt.pts. of an organic peroxide crosslinking agent, and 0.5-10 wt.pts. of an amine base vulcanizing agent, wherein the ternary ethylene-acrylate copolymer rubber having an amine vulcanizable group can be used as a blend rubber with a hydrogenated NBR at a blend rate of 60% by weight or less, or with an EPDM or the other amine vulcanizable acryl rubber at a blend rate of 40% by weight or less. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ethylene-alkyl acrylate copolymer rubber composition for sealing material vulcanization molding. More specifically, the present invention relates to an ethylene-alkyl acrylate copolymer rubber composition that is vulcanized and formed into a sealing material that can be suitably used as a piston seal for a transmission automatic transmission.

  In recent years, with the increase in output of automobiles, the rubber material for sealing is required to have pressure resistance in addition to heat resistance. Conventionally, acrylic rubber (hereinafter referred to as ACM) material has been used for heat resistance requirements, but it has been difficult to apply to pressure-resistant applications because of its low strength. On the other hand, hydrogenated nitrile rubber materials are mainly used for pressure resistance, but there is a problem that heat resistance is inferior to ACM.

As an alternative material, ethylene-alkyl acrylate copolymer rubber (hereinafter referred to as AEM) material can be cited as one of polymers whose heat resistance is equivalent to ACM, but binary (peroxide vulcanization) and ternary systems Both (amine vulcanization system) are required to be improved in terms of strength, and the ternary system also has a problem that the vulcanization speed is slow and the vulcanization time is long.
JP 2000-143894 A

  The object of the present invention is to improve the rubber strength and oil resistance of vulcanized molded products obtained from AEM materials without causing problems such as air entry, and is suitable as a piston seal for mission-type automatic transmissions, etc. Another object of the present invention is to provide an AEM rubber composition that is vulcanized and molded into a sealing material used in the above.

  The object of the present invention is to provide 100 parts by weight of a ternary ethylene-alkyl acrylate copolymer rubber having an amine vulcanizable group, 0.5 to 15 parts by weight of an organic peroxide crosslinking agent, and 0.5 to 10 parts by weight of an amine vulcanizing agent. Part of an ethylene-alkyl acrylate copolymer rubber composition. Ternary ethylene-alkyl acrylate copolymer rubbers with amine vulcanizable groups can also be used as blended rubbers with hydrogenated NBR, EPDM or other amine vulcanizable acrylic rubbers, with a blend ratio of hydrogen It is 60% by weight or less for modified NBR, and 40% by weight or less for EPDM or other acrylic rubber capable of amine vulcanization.

  Vulcanized products obtained by combining peroxide-based crosslinking agents and amine-based vulcanizing agents with AEM having amine-vulcanizable groups have improved rubber strength, oil resistance, and processability (of vulcanization time). (Shortening) can be improved. By using hydrogenated NBR blended with AEM having amine vulcanizable groups, rubber strength and oil resistance can be further improved. Vulcanized moldings having such characteristics are effectively used as sealing materials for oil seals, including O-rings and gaskets, including piston seals for transmission automatic transmissions.

  As the ternary AEM having an amine vulcanizable group, an ethylene-alkyl acrylate copolymer rubber obtained by copolymerizing an epoxy group or a hydroxyl group-containing monomer is used. For example, a commercially available product (DuPont's product Vamac series or the like) can be used as it is. Examples of the epoxy group-containing vinyl monomer to be copolymerized include glycidyl (meth) acrylate, allyl glycidyl ether, glycidyl vinyl ether, and alicyclic epoxy group-containing (meth) acrylate. Examples of the hydroxyl group-containing vinyl monomer to be copolymerized include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Etc. are used. These vinyl monomers are generally used in the copolymerization reaction as a crosslinking point forming monomer in an amount of about 0.1 to 10% by weight. Here, when a binary ethylene-alkyl acrylate copolymer rubber is used, amine vulcanization cannot be performed, so that it is not suitable for use in the present invention.

  This ternary AEM can be blended with hydrogenated NBR, EPDM or other vulcanizable acrylic rubber, preferably hydrogenated NBR. When blended with hydrogenated NBR, it is used at a ratio of 60 wt% or less, preferably 10 to 50 wt% in the blend rubber. These additions further improve rubber strength, oil resistance and processability. When these are added more than this, any of kneading property, oil resistance or strength is deteriorated, which is not preferable.

  The Mooney viscosity and the like of EPDM are not particularly limited, and oil-extended EPDM can be used instead of EPDM or instead of EPDM and a plasticizer (optional blending component). As oil-extended EPDM, EPDM having an oil-extended amount with respect to EPDM of about 50 to 120% by weight, preferably about 70 to 120% by weight is used. As the oil extender, petroleum-based hydrocarbons (paraffinic, naphthenic or aromatic), hydrogenated products thereof, various petroleum resins and the like are used. The addition ratio of oil-extended EPDM varies depending on the oil-extended amount, and is used so that the actual polymer amount becomes the above-mentioned ratio. Other acrylic rubbers that can be vulcanized with amine include, for example, Unimatec products Noxtite PA524 and PA524K and Nippon Zeon products Nipol AR12 and AR14, which are commercially available products. These blended rubbers are used in a proportion of 40% by weight or less, preferably 5 to 30% by weight in the blended rubber.

  As the vulcanization system, a peroxide crosslinking agent and an amine vulcanizing agent are used in combination. Specifically, 0.5 to 15 parts by weight, preferably 1.2 to 10 parts by weight of an organic peroxide crosslinking agent and 0.5 to 10 parts by weight of an amine vulcanizing agent, preferably 100 parts by weight of ternary AEM or blended rubber thereof, preferably 0.5 to 5 parts by weight are added and used. Here, when only the peroxide-based crosslinking agent is used, the strength becomes inferior, and when only the amine-based vulcanizing agent is used, the workability becomes inferior. On the other hand, when the crosslinking agent and the vulcanizing agent are used in a proportion higher than this, the rubber hardness becomes too high and the elongation becomes small, which is not preferable.

  Examples of the organic peroxide as the peroxide-based crosslinking agent include 1,3-bis (tertiary butyl peroxyisopropyl) benzene, di-tertiary butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2, 5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexyne-3, 1,1-di (tert-butylperoxy) -3,3 , 5-trimethylcyclohexane and the like.

  In addition to the organic peroxide crosslinking agent, a co-crosslinking agent made of a polyfunctional unsaturated compound can be used in combination. Examples of the polyfunctional unsaturated compound include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, triallyl (iso) cyanurate, trimethylolpropane tri (meth) acrylate, triallyl trimellitate, N, N Examples include ′ -m-phenylene dimaleimide.

  On the other hand, examples of the amine-based vulcanizing agent include aliphatic polyamine compounds such as hexamethylene diamine, hexamethylene diamine carbamate, hexamethylene diamine-cinnamaldehyde adduct, hexamethylene diamine benzoate, and diamino-modified siloxane, 4,4′-methylene. Alicyclic polyamine compounds such as biscyclohexylamine, bis (4-amino-3-methyldicyclohexyl) methane, 4,4'-methylenebiscyclohexylamine-cinnamaldehyde adduct, or 4,4 '-(α, α-dimethylbenzyl ) Diphenylamine, 4,4'-methylenedianiline, m-phenylenediamine, 4,4'-diaminodiphenyl ether, p-phenylenediamine, p, p'-ethylenedianiline, 4,4 '-(p-phenylenediisopropylene Ridene) dianiline, 4,4 '-(m-phenylenediisopropylidene) dia Phosphorus, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] sulfone Bis [4- (3-aminophenoxy) phenyl] sulfone, 4,4′-bis (4-aminophenoxy) biphenol, bis [4- (4-aminophenoxy) phenyl] ether, 2,2-bis [4 Aromatic polyamine compounds such as-(4-aminophenoxy) phenyl] hexafluoropropane, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene are used.

  When such a polyamine compound crosslinking agent is used, a guanidine compound, a sulfenamide compound or a tertiary amine is used as an accelerator, and about 0.5 to 15 parts by weight per 100 parts by weight of ternary AEM, preferably about It is preferable to use together at a ratio of 1 to 10 parts by weight.

  Examples of the guanidine compound include guanidine, aminoguanidine, 1,1,3,3-tetramethylguanidine, 1,1,3,3-tetraethylguanidine, 1-phenylguanidine, 1,3-diphenylguanidine, triphenylguanidine, 1-benzyl-2,3-dimethylguanidine, 1,3-di-o-tolylguanidine, n-dodecylguanidine, methylolguanidine, dimethylolguanidine, cyanoguanidine, 1,6-guanidinohexane, guanylurea, biguanide, 1 At least one of -o-tolylbiguanide and di-o-tolylguanidine salt of dicatechol borate is used.

  In the copolymer rubber composition containing the above components, a white filler such as carbon black or white carbon (silica) as a reinforcing agent, a processing aid, a plasticizer, an anti-aging agent, etc., as necessary. Are appropriately blended and used.

  The composition is prepared using a known kneading means such as a roll or a kneader, and vulcanization molding is performed by press-crosslinking at about 160 to 190 ° C. for about 5 to 15 minutes, which is necessary. Depending on the conditions, oven vulcanization (secondary vulcanization) is also performed at about 150 to 230 ° C. for about 1 to 15 hours.

  Next, the present invention will be described with reference to examples.

Example 1
3-part AEM (DuPont product Vamac GLS) 100 parts by weight
FEF carbon black (Tokai carbon product Seast G-SO) 70 〃
Stearic acid (Kao product) 2 〃
4,4´- (α, α-Dimethylbenzyl) diphenylamine 2 〃
(Ouchi Emerging Chemicals Antioxidant CD)
Ether type phosphate processing aid (Toho Chemical Products RL210) 1 〃
1,3-bis (tert-butylperoxyisopropyl) benzene 6
(Japanese fat product Peroximon F40: 40% purity) (Actual weight 2.4 〃)
Hexamethylenediamine carbamate 2.25 〃
(Unimatec Cheminox AC-6-66)
Diphenylguanidine (Ouchi Emerging Chemicals Accelerator D) 4 〃
After kneading the above components using a kneader, press crosslinking at 180 ° C for about 8 minutes and oven vulcanization (secondary crosslinking) at 200 ° C for 1 hour. Measurements were made.
ODR: JIS K-6300 compliant, using Toyo Seiki product Lotus Rheometer RIR3, at a measurement temperature of 190 ° C
T90 value measured Normal value: JIS K-6253, 6251 compliant, hardness (Hs), tensile strength (Tb) and elongation (Eb) values measured Air thermal aging test (150 ° C, 500 hours): Hardness change is the oil resistance indicating the hardness change before and after the aging test: Volume change rate after immersion in standard oil No. 3 (IRM903) at 150 ° C for 70 hours: JIS K-6262 compliant (150 ° C 70 hours)

Example 2
In Example 1, the amount of ternary AEM was changed to 80 parts by weight, and 20 parts by weight of hydrogenated NBR (Nippon Zeon product Zetpol 2030L) was used.

Example 3
In Example 1, the amount of ternary AEM was changed to 50 parts by weight, and 50 parts by weight of hydrogenated NBR (Zetpol 2030L) was used.

Example 4
In Example 1, the amount of ternary AEM was changed to 80 parts by weight, and 20 parts by weight of EPDM (Sumitomo Chemical product Espren 586) was used.

Example 5
In Example 1, the ternary AEM amount was changed to 80 parts by weight, and 20 parts by weight of an amine vulcanizable acrylic rubber (Unimatec product Noxtite PA524) was used.

The results obtained in each of the above examples are shown in the following Table 1.
Table 1
Measurement / Evaluation Items Real 1 Real 2 Real 3 Real 4 Real 5
ODR
T90 (min) 2.25 2.20 2.40 2.14 2.02
Normal value
Hs (Duro A) 82 83 84 82 79
Tb (MPa) 16.1 18.2 24.2 20.1 14.2
Eb (%) 200 190 190 250 170
Air heat aging test
Hardness change (Points) +9 +10 +12 +7 +11
Oil resistance
Volume change rate (%) +24 +15 +13 +49 +22
Compression set (%) 33 29 27 31 36

Comparative Example 1
100 parts by weight of amine vulcanizable acrylic rubber (Unimatec product Noxtite PA524)
FEF carbon black (Seast G-SO) 80 〃
Stearic acid (Kao product) 2 〃
4,4´- (α, α-Dimethylbenzyl) diphenylamine (Antioxidant CD) 2 〃
Ether type phosphate processing aid (RL210) 1 〃
Hexamethylenediamine carbamate (Cheminox AC-6-66) 2.3 〃
Diphenylguanidine (Accelerator D) 4 〃
After kneading each of the above components using a kneader, press crosslinking and oven vulcanization (secondary crosslinking) were conducted in the same manner as in Example 1, and the material properties of the obtained vulcanizate were measured.

Comparative Example 2
Hydrogenated nitrile rubber (Zetpol 2030L) 100 parts by weight
FEF carbon black (Seast G-SO) 80 〃
Zinc oxide (堺 chemical) 5 〃
Stearic acid (Kao product) 1 〃
4,4´- (α, α-Dimethylbenzyl) diphenylamine (Antioxidant CD) 2 〃
1,3-bis (tert-butylperoxyisopropyl) benzene 6
(Peroximon F40: 40% purity) (Actual weight 2.4 〃)
After kneading each of the above components using a kneader, press crosslinking and oven vulcanization (secondary crosslinking) were conducted in the same manner as in Example 1, and the material properties of the obtained vulcanizate were measured.

Comparative Example 3
In Example 1, hexamethylenediamine carbamate and diphenylguanidine were not used.

Comparative Example 4
In Example 1, 1,3-bis (tert-butylperoxyisopropyl) benzene was not used.

Comparative Example 5
In Example 1, the same amount of binary AEM (DuPont Vamac DP) was used instead of ternary AEM, and hexamethylenediamine carbamate and diphenylguanidine were not used.

Comparative Example 6
In Example 4, the amount of ternary AEM was changed to 50 parts by weight, and the amount of EPDM (Espren 586) was changed to 50 parts by weight.

Comparative Example 7
In Example 5, the amount of ternary AEM was changed to 50 parts by weight, and the amount of amine vulcanizable acrylic rubber (Noxtite PA524) was changed to 50 parts by weight.

The results obtained in the above comparative examples are shown in the following Table 2.
Table 2
Measurement / evaluation item ratio 1 ratio 2 ratio 3 ratio 4 ratio 5 ratio 6 ratio 7
ODR
T90 (min) 5.82 2.33 2.36 5.58 4.10 3.80 2.06
Normal value
Hs (Duro A) 77 86 81 84 84 83 76
Tb (MPa) 11.8 30.8 7.11 15.2 14.1 16.8 11.1
Eb (%) 190 210 380 290 260 270 130
Air heat aging test Hardness change (Points) +9 +15 +8 +9 +8 +8 +10
Oil resistance Volume change rate (%) +24 +14 +30 +29 +57 +80 +20
Compression set (%) 12 30 25 34 20 28 37

Claims (4)

  100 parts by weight of rubber comprising 100 to 40% by weight of ternary ethylene-alkyl acrylate copolymer rubber having amine vulcanizable group and 0 to 60% by weight of hydrogenated NBR, 0.5 to 15 parts by weight of organic peroxide crosslinking agent And an ethylene-alkyl acrylate copolymer rubber composition for sealing material vulcanization molding, comprising 0.5 to 10 parts by weight of an amine vulcanizing agent.   100 parts by weight of a rubber comprising 100 to 60% by weight of a ternary ethylene-alkyl acrylate copolymer rubber having an amine vulcanizable group and 0 to 40% by weight of EPDM or other acrylic rubber capable of amine vulcanization, organic peroxidation An ethylene-alkyl acrylate copolymer rubber composition for vulcanization molding of a seal material, comprising 0.5 to 15 parts by weight of a product cross-linking agent and 0.5 to 10 parts by weight of an amine vulcanizing agent.   A sealing material obtained by vulcanizing and molding the ethylene-alkyl acrylate copolymer rubber composition according to claim 1. The sealing material according to claim 3, which is used as a piston seal for an automatic transmission.