JPH0735453B2 - Hydrogenated NBR composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hydrogenated NBR composition. More specifically, it relates to a hydrogenated NBR composition which is excellent in roll processability and can give a vulcanized product having a small compression set.

[Conventional technology]

Hydrogenated acrylonitrile-butadiene copolymer rubber (hydrogenated NBR) is obtained by hydrogenating the double bond of butadiene in ordinary acrylonitrile-butadiene copolymer rubber and has a chemical stability at a hydrogenation rate of about 80% or more. It has excellent chemical resistance, sour gasoline resistance and heat resistance. Also, high strength, low compression set compounding is possible. Therefore, by effectively utilizing these properties, O-rings, gaskets, diaphragms, hoses, belts, etc.
It is used in a wide range of applications.

Although hydrogenated NBR has such a wide range of applications, it has a problem in workability. That is, during roll kneading, the rubber belt does not adhere to the roll, which hinders the addition of fillers, plasticizers, vulcanizing agents (organic peroxides) and the like for that purpose. Further, even when the roll is dispensed, the dimensional stability of the dough is poor due to the lack of tackiness of the roll, which causes a shortage of the dough during crosslinking.

In order to solve these problems, it is possible to add a processing aid such as an alkylphenol resin. Although the addition of such a processing aid slightly improves roll processability, it has various physical properties inherent to rubber. Raises a new problem of drastically reducing.

[Problems to be solved by the invention]

The present inventor, as a result of various investigations for a method of improving the roll processability of the hydrogenated NBR, without substantially impairing the above-mentioned physical properties inherent to the hydrogenated NBR. It has been found that such a problem can be effectively solved by adding it.

[Means for solving problems]

Therefore, the present invention relates to a hydrogenated NBR composition, which comprises a hydrogenated acrylonitrile-butadiene copolymer rubber and liquid polybutadiene.

As the hydrogenated NBR, one having a hydrogenation rate of about 80% or more is used, and the heat resistance increases as the hydrogenation rate increases up to a hydrogenation rate of 100%, but generally, the degree of heat resistance required, From the viewpoint of cost, those with a hydrogenation rate slightly lower than 100% are used.

From the viewpoint of cross-linking ability, sulfur cross-linking is possible except for those with 100% hydrogenation rate, but 100% hydrogenation rate due to various characteristics such as heat resistance, gasoline resistance and compression set. It is preferable to carry out peroxide crosslinking, including those described above. As the cross-linking agent, di-tert-butyl peroxide, dicumyl peroxide, tert-butyl cumyl peroxide, 1,1
-Bis (tertiary butylperoxy) -3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-bis (tertiary butylperoxy) hexyne-3, ditertiary butylperoxydiisopropylbenzene, 2,5-Dimethyl-2,5-dibenzolperoxyhexane, tert-butylperoxybenzoate, tert-butylperoxyisopropyl carbonate and the like are used.

Liquid polybutadiene is a poly-1,2-butadiene having an average molecular weight of about 1000 to 3000, and has a primary hydroxyl group and a carboxyl group at both ends, and these are generally about 100 parts by weight of hydrogenated NBR. It is used in a proportion of 1 to 20 parts by weight. Within such a range, the roll processability and compression set are more significantly improved as the addition ratio of liquid polybutadiene is increased, but if it is used at a ratio higher than this, the hardness and elongation of the normal state physical properties, The heat resistance will deteriorate. On the other hand, if the addition ratio is less than this, improvement in roll processability cannot be achieved. In consideration of such physical properties and workability, it is generally appropriate to add about 5 parts by weight of low hardness liquid polybutadiene or about 10 parts by weight of high hardness liquid polybutadiene.

The composition is prepared by using a cross-linking agent, carbon black, and other necessary compounding components in addition to the above essential components. The above components are kneaded by open kneading using an open roll, closed kneading using a kneader, intermixer, Banbury mixer, or solution kneading. In the case of open-type kneading, hydrogenated NBR is wrapped around an open roll and masticated, then a small amount of a compounding component other than the crosslinking agent is added, and finally the crosslinking agent is added. Further, in the case of the closed type kneading, each compounding component other than the crosslinking agent is put into the closed type kneading machine all at once, and after a few minutes, the mixture is discharged, and then the crosslinking agent is added using an open roll.

The composition thus prepared generally has a composition of about 160-170.
It is vulcanized under vulcanization conditions of about 15 to 20 minutes at ℃.

〔The invention's effect〕

The hydrogenated NBR composition according to the present invention improves roll processability by adding liquid polybutadiene to the hydrogenated NBR without substantially deteriorating the desirable physical properties originally possessed by the hydrogenated NBR.

〔Example〕

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

Example 1 Hydrogenated NBR (hydrogenation rate 90%) [Nippon Zeon Products Zetpol 2020] 100 parts by weight SRF carbon black [Chubu Carbon Products HTC # S] 80 Zinc white (No. 1) 5 Stearic acid 0.5 Di (butoxyethoxy) Ethyl) adipate [Product of Thiokol Chemical Co.] 5 Di-tert-butylperoxydiisopropylbenzene [Sankenox product SanpeloxTY-13] 4 Trimethylolpropane trimethacrylate [Mitsubishi Rayon product Acryester TMP] 2 Liquid polybutadiene [Nippon Soda product B- 3000] 1 Of the above ingredients, hydrogenated NBR is wrapped around a 12-inch open roll and masticated for 1 to 2 minutes, then a small amount of ingredients other than the cross-linking agent are added to the mixture for 20 to 30 minutes. After the addition is complete, the crosslinker is added within about 10 minutes. The hydrogenated NBR composition thus prepared was vulcanized by heating at 170 ° C. for 15 minutes. The following items were measured for the obtained vulcanized product.

(Normal physical properties, compression set) According to JIS K-6301 vulcanized rubber physical test method (Roll processability) Processed at 60 ° C using a 12-inch open roll. ○: Wrap around roll with a fabric thickness of 10 mm or more. : Wound with a material thickness of 5 mm, but not wound with 10 mm ×: Not wound with a material thickness of 5 mm Examples 2 to 4 In Example 1, the amount of SRF carbon black added was 70.
The amount of liquid polybutadiene added was changed to 5 parts by weight (Example 2), 10 parts by weight (Example 3) or 20 parts by weight (Example 4).

Comparative Examples 1 to 5 In Example 2, the addition amount of SRF carbon black was 85
In addition to parts by weight, the same amount of the following resin was used instead of liquid polybutadiene. Comparative Example Compound resin 1 None 2 Phenolacetylene resin [BASF product Koresin K1-1] 3 Coumaron-indene resin [Nippon Steel Chemicals NG-4] 4 Alkylphenol resin [Japan Terpene Chemical Product SR-310] 5 Hydrogenated rosin resin [Arakawa Hayashi Chemical Product Ester Gum H] The same measurements and evaluations as in Example 1 were performed on the above Examples 2 to 4 and Comparative Examples 1 to 5, and the results are also shown in the following table.

From this result, the following can be said.

(1) In the hydrogenated NBR composition according to the present invention, roll processability and compression set are improved by adding liquid polybutadiene, and the improvement effect becomes remarkable as the addition ratio of liquid polybutadiene increases. . Further, the normal physical property values are not substantially impaired by the blending of liquid polybutadiene.

(2) On the other hand, when various resins as commonly used tackifiers are blended, no particular improvement in roll processability is observed, and rather compression set is deteriorated.

Claims (1)

[Claims] 1. A hydrogenated NBR composition comprising 100 parts by weight of hydrogenated acrylonitrile-butadiene copolymer rubber and 1 to 20 parts by weight of liquid polybutadiene.