JP2003342422A - Rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogenated nitrile/butadiene rubber composition simultaneously improved in heat resistance and permanent compression set resistance while hardly damaging mechanical strength (vulcanization properties) and oil resistance inherent in the hydrogenated nitrile/butadiene rubber. <P>SOLUTION: The hydrogenated nitrile/butadiene rubber composition comprises a hydrogenated nitrile/butadiene rubber having a bound acrylonitrile content of 15-50 wt.%, an iodine value of 20-70 g/100 g and a Mooney viscosity ML1+4 at 100°C within the range of 100-160 and, incorporated therewith, 1-20 pts.wt., based on 100 pts.wt. of the hydrogenated nitrile/butadiene rubber, of an organic peroxide. Thus, heat resistance and permanent compression set resistance are simultaneously improved while hardly damaging mechanical strength (vulcanization properties) and oil resistance of the hydrogenated nitrile/butadiene rubber. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

This invention relates to hydrogenated nitrile butadiene rubber. More specifically, it relates to a hydrogenated nitrile butadiene rubber capable of giving a vulcanized product having excellent heat resistance, mechanical strength (normal physical properties) and compression set resistance.

[0002]

2. Description of the Related Art Hydrogenated nitrile butadiene rubber is widely used around the engine as a sealing material for O-rings, gaskets, packings and the like because it is excellent in heat resistance, compression set resistance and fuel oil resistance. However, due to the higher temperature in recent years due to higher performance, smaller size, lighter weight, etc.,
The conventional hydrogenated nitrile butadiene rubber composition has a new problem of insufficient heat resistance and compression set resistance. Although a low iodine value hydrogenated nitrile butadiene rubber composition conventionally used is excellent in heat resistance, it has a problem that compression set resistance cannot be satisfied. Further, although the hydrogenated nitrile butadiene rubber composition having a high iodine value is excellent in compression set resistance, there is a problem that heat resistance and mechanical strength (normal physical properties) cannot be satisfied.

[0003]

DISCLOSURE OF THE INVENTION The object of the present invention is to reduce the heat resistance and compression permanent resistance of hydrogenated nitrile butadiene rubber without substantially impairing the mechanical strength (vulcanization properties) and oil resistance of the rubber. It is an object of the present invention to provide a hydrogenated nitrile butadiene rubber composition having improved strainability at the same time.

[0004]

The object of the present invention is as follows.
The amount of bound acrylonitrile is 15 to 50% by weight, preferably 20 to 45% by weight, the iodine value is 20 to 70 g / 100 g, preferably 30 to 60 g / 100 g, and the Mooney viscosity ML1.
+ 4 @ 100 [deg.] C .: 1 to 20 parts by weight, preferably 3 to 10 parts by weight, of organic peroxide based on 100 parts by weight of hydrogenated nitrile butadiene rubber, relative to hydrogenated nitrile butadiene rubber. A hydrogenated nitrile butadiene rubber composition containing the same, and a hydrogenated nitrile butadiene rubber composition containing 0.5 to 10 parts by weight, preferably 1 to 8 parts by weight of a polyfunctional unsaturated compound in the rubber composition. Achieved by things.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The hydrogenated nitrile butadiene rubber used in the present invention is obtained by hydrogenating a nitrile butadiene rubber with a metal such as a platinum or rhodium catalyst. The hydrogenated nitrile butadiene rubber has an amount of bound acrylonitrile of 15 to 50% by weight, preferably 20 to 45.
If the amount by weight and the amount of bound acrylonitrile are too large, the oil resistance is excellent, but the low-temperature property is poor, and if the amount of bound acrylonitrile is too small, the low-temperature property is excellent, but the oil resistance is poor.
Further, a copolymer rubber of acrylonitrile and butadiene or an ethylenically unsaturated compound thereof was copolymerized therewith.
Hydrogenated nitrile butadiene rubber, which is a terpolymer rubber, can also be used.

The iodine value is 20 to 70 g / 100 g, preferably 30 to 60 g / 100 g, and the Mooney viscosity ML1 + 4.
@ 100 ° C .: Hydrogenated nitrile butadiene rubber in the range of 100 to 160 is used. Although a low iodine value hydrogenated nitrile butadiene rubber composition has excellent heat resistance, it has a problem in that it is unsatisfactory with respect to compression set resistance. This is because although the product has excellent compression set resistance, there is a problem that heat resistance and mechanical strength (normal physical properties) cannot be satisfied.

The organic peroxide used in the present invention includes dicumyl peroxide, 2,5-dimethyl-2,
5-di (t-butylperoxyl) hexane, 2,5-dimethyl-2,5-di (t-butylperoxyl) hexyne, 1,3-bis (t-butylperoxyl-iso-propyl) benzene, etc. Is commonly used. Such a peroxide is used in an amount of 1 to 20 parts by weight, preferably 3 to 10 parts by weight, based on 100 parts by weight of hydrogenated nitrile butadiene rubber. If the blending amount of the organic peroxide is less than this, a vulcanizate having a sufficient cross-linking density cannot be obtained, and if used in a proportion higher than this, foaming and vulcanization molding cannot be performed,
Or even if it is possible, rubber elasticity and elongation will be reduced. Two or more kinds of these peroxides may be used in combination.

The composition obtained in the present invention may optionally contain compounding agents usually used for rubber.
For example, carbon black, white carbon, or the like is used as the filler. As carbon black,
For example, generally used carbon blacks such as furnace black produced by incompletely burning oil and thermal black produced by thermally decomposing natural gas are used. As white carbon (reinforcing silica), dry method white carbon produced by a thermal decomposition method of a halogenated silicic acid or an organic silicon compound, a method of heating and reducing silica sand, and an air oxidation of vaporized SiO are used. Examples include wet-process white carbon produced by a thermal decomposition method of sodium acid. Those commercially available for the rubber industry can be used as they are.
White fillers such as silica, clay, talc, calcium carbonate, diatomaceous earth, quartz powder, plasticizers, antioxidants, pigments,
Zinc white, a silane coupling agent, a co-crosslinking agent and the like can be optionally mixed.

In the composition, in addition to the above essential components, triallyl (iso) cyanurate, trimethylolpropane tri (meth) acrylate, triallyl trimellitate,
It is preferable to add a polyfunctional unsaturated compound such as N, N'-m-phenylene bismaleimide to about 0.5 to 10 parts by weight, preferably about 1 to 8 parts by weight, per 100 parts by weight of hydrogenated nitrile butadiene rubber. . The compounding of a polyfunctional unsaturated compound is effective in further improving heat resistance and compression set. However, if it is used at a ratio higher than this, the rubber elasticity and elongation decrease. Two or more of these polyfunctional unsaturated compounds may be used in combination.

In addition, talc, clay, graphite,
Commonly used in the rubber industry such as fillers such as calcium silicate, processing aids such as stearic acid, palmitic acid and paraffin wax, acid acceptors such as zinc oxide and magnesium oxide, antioxidants and plasticizers. Various compounding agents are appropriately added and used.

The method for preparing the rubber composition of the present invention is not particularly limited, and the rubber composition can be prepared by adding the above-mentioned components and mixing them with an ordinary kneading machine such as a Banbury mixer, a kneader or a roll. The rubber composition thus obtained can be vulcanized at a temperature of about 150 ° C. to 230 ° C. for about 30 seconds to 20 minutes. Secondary vulcanization may be performed if necessary. The molding method includes compression molding, injection molding, transfer molding and the like.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0013]

[Examples and Comparative Examples] The polymer and the compounding agent were kneaded by a kneader or an open roll in the compounding formulation shown in Table 1, and the kneaded product was press-vulcanized at 170 ° C. for 5 minutes,
Then, secondary vulcanization was performed at 150 ° C. for 4 hours. Then JI
The normal physical properties of each vulcanizate were measured based on the S standard, and the results are also shown in Tables 1 and 2.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

[Table 3]

[0017]

Thus, according to the present invention, the amount of bound acrylonitrile is 15 to 50% by weight, preferably 20 to 45% by weight, and the iodine value is 20 to 70 g / 100 g, preferably 30.
~ 60g / 100g, Mooney viscosity ML1 + 4 @ 10
0 [deg.] C .: 1 to 20 parts by weight, preferably 3 to 10 parts by weight, per 100 parts by weight of hydrogenated nitrile butadiene rubber, based on the hydrogenated nitrile butadiene rubber. And a hydrogenated nitrile butadiene rubber composition containing the polyfunctional unsaturated compound in an amount of 0.5 to 10 parts by weight, preferably 1 to 8 parts by weight. By using it, the heat resistance and compression set resistance of the hydrogenated nitrile butadiene rubber can be improved at the same time without substantially impairing the mechanical strength (vulcanization physical properties) and oil resistance originally possessed by the hydrogenated nitrile butadiene rubber. Therefore, the hydrogenated NBR composition according to the present invention is effectively used as a molding material for sealing parts, such as O-rings, gaskets, packings, and oil seals, which are used under temperature conditions of -40 ° C to 150 ° C.

Claims (2)

[Claims] 1. An organic peroxide is added to a hydrogenated nitrile butadiene rubber having a bound acrylonitrile amount of 15 to 50% by weight, an iodine value of 20 to 70 g / 100 g, and a Mooney viscosity ML1 + 4 @ 100 ° C. of 100 to 160. 1 to 20 per 100 parts by weight of hydrogenated nitrile butadiene rubber
A hydrogenated nitrile butadiene rubber composition containing 1 part by weight. 2. A polyfunctional unsaturated compound of 0.5 to 1 is further added.
The hydrogenated nitrile butadiene rubber composition according to claim 1, which contains 0 part by weight.