JPH0737555B2 - Hydrogenated acrylonitrile-butadiene rubber vulcanizing composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a high-strength, heat-resistant, sour gasoline-resistant, oil-resistant hydrogenated acrylonitrile-butadiene rubber vulcanizing composition having improved ozone cracking resistance. .

(Prior Art) In recent years, a demand for a rubber composition having properties such as oil resistance, sour gasoline resistance, weather resistance, and cold resistance has been further increased from various fields including the automobile industry. Further, a member having rubber elasticity, relatively light weight, and high mechanical strength has high industrial utility value.

Acrylonitrile-butadiene copolymer rubber (hereinafter "NB
R) is widely used as an oil resistant rubber, and in order to improve the strength and wear resistance of this NBR, a carboxyl group-containing monomer is also copolymerized as a third component. . Since these conventional NBRs contain a large amount of carbon-carbon double bonds, they have poor heat resistance, weather resistance and sour gasoline properties.

(Problems to be Solved by the Invention) JP-A-54-132647 proposes to improve weatherability and sour gasoline resistance by partially hydrogenating the butadiene portion of NBR. Strength improvement is not sufficient.

In this way, the conventional reforming technology satisfies the requirements of heat resistance, weather resistance, and sour gasoline resistance, and has a high strength NBR.
It has never been obtained.

(Means for Solving Problems) The inventors of the present invention have conducted intensive studies to solve these problems, and as a result, copolymerized a copolymerizable unsaturated carboxylic acid monomer as a third component. By combining carbon black, a vulcanizing agent, and a vulcanization accelerator into a polymer obtained by hydrogenating the carbon-carbon double bond portion of the NBR above a specified ratio, the excellent heat resistance of hydrogenated NBR can be obtained. It was found that a high-strength, oil-resistant NBR vulcanized composition having significantly improved weatherability without impairing the properties and sour gasoline resistance was achieved, and the present invention was reached.

That is, an object of the present invention is to provide a high-strength, oil-resistant hydrogenated NBR vulcanizing composition having weather resistance (heat resistance and sour gasoline resistance with significantly improved ozone crack resistance).

The purpose is to obtain a copolymerizable unsaturated carboxylic acid monomer by copolymerizing 0.1 to 10% by weight with 100% by weight of a rubber component consisting of 45 to 80% by weight of butadiene and 20 to 55% by weight of acrylonitrile. A vulcanized rubber composition obtained by blending a carbon black, a vulcanizing agent, and a vulcanization accelerator to a rubber obtained by hydrogenating at least 70% or more of the carbon-carbon double bond portion of the ternary polymer Easily achieved.

Hereinafter, the present invention will be described in detail.

The rubber component used in the present invention includes butadiene 45-
NBR consisting of 80% by weight and 20-55% by weight acrylonitrile
However, it is more preferable to use NBR containing 50 to 75% by weight of butadiene and 25 to 50% by weight of acrylonitrile.

If the amount of acrylonitrile is too large, the cold resistance and rubber properties of the rubber composition will be insufficient, and if it is too small, the oil resistance will be insufficient. Above, it is selected as a suitable range.

In the present invention, the unsaturated carboxylic acid monomer is 0.1 to 10% by weight, preferably 0.5 to 100% by weight with respect to 100% by weight of the rubber component.
7% by weight is copolymerized to obtain a ternary copolymer.

This ternary copolymer is prepared from butadiene, acrylonitrile and a copolymerizable unsaturated carboxylic acid monomer in the presence of a redox initiator and the like by a usual emulsion polymerization method. Further, the amount of the copolymerizable unsaturated carboxylic acid monomer is 0.1
If it is less than 10% by weight, the effect of improving the mechanical strength is weakened, and if it exceeds 10% by weight, the cold resistance tends to deteriorate significantly, which is not preferable.

The copolymerizable unsaturated carboxylic acid monomer used in the present invention is preferably a compound selected from at least one of acrylic acid, methacrylic acid, crotonic acid, and oleic acid.

The hydrogenated acrylonitrile-butadiene rubber vulcanizing composition which is the object of the present invention has a carbon-carbon double bond portion of the above terpolymer of 70% or more, preferably 85% or more, more preferably 90% or more. A rubber obtained by hydrotreating, a carbon black sulfur-based or peroxide-based vulcanizing agent and its vulcanization accelerator, and if necessary, a filler and a plasticizer used in ordinary rubber compositions. It is prepared by blending additives such as an anti-aging agent, mixing with a kneader such as a Banbury mixer or a roll, and vulcanizing according to a conventional method.

The above-mentioned hydrogenation treatment selectively hydrogenates the carbon-carbon double bond portion of the butadiene portion while retaining the nitrile group of the acrylonitrile portion of the terpolymer of the present invention. Japanese Patent No. 3700637, Japanese Patent Publication No. 4
It is carried out by a generally known method disclosed in Japanese Patent Application Laid-Open No. 5-39275 or Japanese Patent Application Laid-Open No. 50-71681.

If the hydrogenation rate of the carbon-carbon double bond portion is less than 70%, the effect of improving the heat resistance, weather resistance, sour gasoline property and the like of the obtained rubber becomes small, which is not preferable.
Further, the higher the hydrogenation rate, the more the property improving effect increases, but when obtaining a vulcanized rubber composition by sulfur vulcanization treatment, if the hydrogenation rate is 97% or more, the time required for vulcanization becomes longer. Becomes
The hydrogenation rate is preferably less than 97% because the production efficiency decreases.

In the kneading treatment, other polymer compounds such as polyvinyl chloride (PVC) and ethylene-propylene terpolymer (EPDM) may be mixed and used.

(Examples) Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the following Examples unless it exceeds the gist.

Examples 1-2 and Comparative Examples 1-4 A terpolymer based on butadiene-acrylonitrile-unsaturated carboxylic acid was prepared according to the polymerization recipe shown in Table 1. After dissolving these copolymers in tetrahydrofuran, add a hydrogenation catalyst (Pd carbon) and add 50% hydrogen.
The pressure was increased to kg / cm ² and the hydrogenation reaction was carried out at 75 ° C. for 4 hours. No reduction of nitrile groups was observed in the recovered polymer, and only 90% of the carbon-carbon double bonds were hydrogenated. The hydrogenation rate was determined by the iodine value.

Next, these polymers were kneaded in a Banbury mixer according to the formulation shown in Table 2. The resulting blend is 160 ° C x 20
Press vulcanization under the condition of minutes to prepare a vulcanized product for testing and
The results of these physical property measurements are shown in the table.

In addition, for comparison, in Comparative Examples 1 and 2, a hydrotreated product and a non-hydrogenated product were prepared using the copolymer of the present invention in which the unsaturated carboxylic acid was not blended, and the same as in the examples. To obtain a vulcanized product.

Further, in Comparative Examples 3 and 4, vulcanized products were obtained in the same manner as in Examples without hydrotreating the ternary copolymers used in Examples 1 and 2. The results of measuring the respective physical properties are also shown in Table 3.

As can be seen from Table 3, in the present invention examples (Examples 1 and 2), ozone resistance is particularly improved as compared with Comparative Examples 1 to 4, and heat resistance, lubricating oil resistance and sour gasoline resistance are also improved. Rate of change in tensile strength (△ TB), rate of change in elongation (△)
Since the absolute value of EB) is low and the high tensile strength (TB) level is maintained, the vulcanized rubber composition according to the present invention has excellent heat resistance and sour gasoline resistance, and particularly has excellent ozone crack resistance. It is apparent that it is an improved high strength oil resistant rubber.

Physical properties were measured according to the following methods.

1) Normal physical properties (tensile test): JIS K6301 2) Hardness: JIS K6301 3) Heat resistance: JIS 6301 (gear oven 130 ℃ × 168hrs) 4) Ozone resistance: JIS 6301 (40 ℃, 50pphm, static 20%) 5) Lubricating oil resistance (immersion test): JIS 6301 (JIS # 3 oil, 135 ° C x 168hrs) 6) Sour gasoline: 2% by weight lauroyl peroxide (LPO) dissolved in commercial Regular gasoline , Sour gasoline was prepared. Four JIS No. 3 dumbbells were dipped in this and left at 60 ° C. After 72 hours, it was taken out and the physical property values were measured.

In Table 3, TB: tensile strength, ΔTB: tensile strength change rate, EB: elongation, ΔEB: elongation change rate, HS: hardness, ΔHS: hardness change rate.

Further, in the ozone resistance in the table, "NC" means no crack, and "B or C-1 to 4" indicates the deteriorated state described in Table 8 of JIS K6301.

(Effect) According to the present invention, a high-strength hydrogenated acrylonitrile-butadiene rubber vulcanization composition having improved ozone cracking resistance, excellent heat resistance, sour gasoline resistance, and oil resistance is obtained. When used as an industrial belt, a fuel hose, a packing material, an oil seal, a diaphragm or a rubber member for crude oil excavation, it exerts a remarkable effect.

Claims (2)

[Claims] 1. A rubber component comprising 45 to 80% by weight of butadiene and 20 to 55% by weight of acrylonitrile, relative to 100% by weight of a rubber component,
Hydrogenation obtained by hydrogenating at least 70% or more of the carbon-carbon double bond portion of the ternary copolymer obtained by copolymerizing 0.1 to 10% by weight of the copolymerizable unsaturated carboxylic acid monomer A hydrogenated acrylonitrile-butadiene rubber vulcanizing composition, characterized in that carbon black, a vulcanizing agent, and a vulcanization accelerator are mixed with acrylonitrile-butadiene rubber. 2. The copolymerizable unsaturated carboxylic acid monomer is a compound selected from at least one of acrylic acid, methacrylic acid, crotonic acid and oleic acid. The composition as described.