JPH02140257A - Rubber composition - Google Patents

Abstract

PURPOSE:To obtain a vulcanizable rubber composition having excellent resistance to gasoline and sour gasoline balanced with freeze resistance by mixing an acrylic rubber with an acrylic copolymer having a specific structure. CONSTITUTION:The objective composition is produced by compounding (A) an acrylic copolymer produced by the polymerization (preferably emulsion polymerization) of (A1) 90-99.5wt.% of an acrylic acid ester and/or methacrylic acid ester of formula (R<1> is H or methyl; R<2> is cyano-substituted alkyl; n is >=1 and number-average of n is 1-5) and (A2) 0.5-10wt.% of an unsaturated compound (e.g., 2-chloroethyl vinyl ether or allyl glycidyl ether) having active functional group (e.g., active halogen group or epoxy group) in the molecule and (B) an acrylic rubber at a weight ratio (A/B) of 95/5-5/95, preferably 60/40-10/90 and adding (C) a vulcanizing agent, etc., to the mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a vulcanizable rubber composition that has excellent gasoline resistance, sour gasoline resistance, and a good balance with cold resistance.

<Prior Art> Acrylic rubber is a rubber with excellent heat resistance and lubricant resistance, and is widely used as sealing materials and hose materials in automobile-related fields. However, it is not resistant to fuel oils with a low aniline point and is not suitable for use as a fuel hose. As a means to improve this, there is a method of copolymerizing monomers with high polarity, but although this improves oil resistance, it has the problem of decreasing cold resistance. Furthermore, in recent years, due to engine improvements aimed at automobile exhaust gas control measures and improved performance, the atmosphere in which rubber is used has become high in temperature, and there is a demand for rubber with excellent heat resistance and gasoline resistance. Another problem has arisen in that sour gasoline produced by oxidation of gasoline deteriorates rubber.

<Problems to be Solved by the Invention> The present inventors have conducted various studies in view of the above situation, and have found that the above problems can be solved by mixing an acrylic copolymer having a specific structure with acrylic rubber. I found that it can be improved.

Means for Solving the Problems> That is, the present invention provides (1) (I) (A) an acrylic ester and/or a methacrylic ester having the structure of the following formula (a) (where R1 is hydrogen). or a methyl group, R2 is a cyano-substituted alkyl group, n is an integer of 1 or more, and its number average value is 1 to 5.) (B) an acrylic copolymer consisting of a crosslinkable monomer and (II) Contains acrylic rubber and has a weight ratio of I)/(II) of 9515 to 5/
95.

The present invention will be explained in detail below.

The monomer (A) of the acrylic copolymer (I) used in the present invention is an acrylic ester and/or a methacrylic ester having the structure of the following formula (a).

(Here, R1 is hydrogen or a methyl group, R2 is a cyano-substituted alkyl group, n is an integer of 1 or more, and the number average value is 1 to 5.) As a specific example of R2, a cyano-substituted alkyl group 1-cyanoethyl group, 2-cyanoethyl group, 1-cyanopropyl group, 2-cyanopropyl group, 3-cyanopropyl group, 4-cyanopropyl group,
Examples include a cyanobutyl group and a 6-cyanohexyl group.

The acrylic ester or methacrylic ester of the monomer (A) is a mixture of substances having different molecular weights, that is, different n in formula (a), but it is possible to use the mixture as it is. Of course, there is no problem in using the acrylic ester or methacrylic ester separated by distillation or the like and having no distribution in molecular weight. In the present invention, the number average value of n is 1-5. Additionally, the acrylic ester or methacrylic ester of monomer (A) may contain a compound represented by the following formula (b,) due to its manufacturing process, but if it is 20% by weight or less, there is no particular problem. do not have.

CI+2-C-C-0-I? '(
b) (Here, R3 is hydrogen or a methyl group, R4 is a cyano-substituted alkyl group, n is an integer of 1 or more, and the number average value is 1 to 5.) In the present invention, acrylic copolymers Monomer (A
) is preferably used in an amount of 90 to 99.5% by weight.

The monomer (B) is a unit that acts as a crosslinking point during vulcanization in the rubber composition of the present invention, and is a monomer containing an active functional group such as an active halogen group, an epoxy group, or a carboxylic acid group in the molecule. Saturated compounds are used. Specific examples of the active halogen group-containing unsaturated compound include 2-chloroethyl vinyl ether, vinyl chloroacetate, allyl chloroacetate, chloromethylstyrene, and 2-chloroethyl methacrylate. Specific examples of the epoxy group-containing unsaturated compound include allyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate.

Further, examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid. These crosslinking monomers can be used alone or as a mixture of two or more. In the present invention, the amount of monomer (B) used in the acrylic copolymer is preferably 0.5 to 10% by weight.

By using a commonly used radical initiator, the mixture of the above-mentioned (11mers (A) and (B)) can be used as a component in the present invention by known polymerization methods such as bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization. The acrylic copolymer (I) can be produced. Emulsion polymerization is preferred as the polymerization method.

Next, the acrylic rubber (II) used in the present invention is a known acrylic rubber, for example, a multi-component copolymer consisting of an acrylic acid alkyl ester and/or an acrylic acid alkoxy-substituted alkyl ester compound and a crosslinkable monomer. Examples include composite rubber or multi-component copolymer rubber consisting of an acrylic acid alkyl ester and/or an acrylic acid alkoxy-substituted alkyl ester compound, a crosslinkable monomer, and another ethylenically unsaturated compound copolymerized with these. It will be done. The crosslinking monomer of the acrylic rubber (II) is preferably a compound that covulcanizes with the crosslinking monomer (B) used in the acrylic copolymer (I).

The rubber composition of the present invention also includes the above-mentioned acrylic copolymer (
The weight ratio of I) and acrylic rubber (II) is 9515
~5/95, preferably 60/40~10/9
It is 0. If the acrylic copolymer (I) exceeds 95% by weight in the rubber composition, problems may arise in processability and mechanical strength, and if it is less than 5% by weight, the effects of the present invention are small.

The method of mixing the composition of the present invention is based on the method of mixing the composition of the present invention.
) and acrylic rubber (n) using a mixer such as a roll or a Banbury mixer-intermixer, or a method of mixing acrylic copolymer (I) and acrylic rubber (II) in latex form or suspension. Examples include a method in which the materials are mixed in the same state and then coagulated and co-precipitated, but there are no particular limitations.

The rubber composition of the present invention can be vulcanized by a method similar to a commonly known acrylic rubber vulcanization method.

Vulcanization is performed using the monomer (B) that acts as a crosslinking point for the acrylic copolymer (I) of the rubber composition or the acrylic rubber (
II) A vulcanizing agent selected depending on the type of monomer that acts as a crosslinking point, as well as a vulcanization accelerator, reinforcing agent, filler, plasticizer, anti-aging agent, stabilizer, etc., are blended as necessary. will be carried out.

<Examples> The present invention will be specifically explained below using Examples, but the scope of the present invention is not limited thereto.

Synthesis Examples 1 to 3 100 parts by weight of a monomer mixture having the composition shown in Table 1, one fifth of a mixture of 0.03 parts by weight of n-dodecylmercaptan, 4 parts by weight of polyoxyethylene lauryl ether, and Eight parts of polyoxyethylene sorbitan tristearate and one-half of an emulsifier solution consisting of 400 parts by weight of deionized water were stirred and emulsified.

Pour this emulsion into a separable flask and adjust the temperature to 10°.
C, 0.03 parts by weight of ferrous sulfate, 0.01 parts by weight of distrium ethylenediaminetetraacetate, Rongarit I-
After adding 0.04 parts by weight, a solution consisting of 0.02 parts by weight of tert-butyl hydroperoxide and 100 parts by weight of deionized water was added dropwise to initiate polymerization. Thereafter, an emulsified monomer obtained by emulsifying the remaining monomer mixture and emulsifier solution was added dropwise, and polymerization was carried out for about 5 hours. After the polymerization was completed, 0.1 part by weight of hydroquinone was added to complete the polymerization.

The obtained copolymer latex was poured into an aqueous calcium chloride solution at 80° C. to isolate the copolymer, thoroughly washed with water, and then dried to obtain an acrylic copolymer (I).

Examples], ~3, Comparative Examples 1 and 2 Acrylic copolymers and acrylic rubbers (1) obtained in Synthesis Examples 1 and 2 [N1pol AR-71 manufactured by Nippon Zeon Co., Ltd.] were rolled according to the formulation shown in Table 2. Knead 17
A vulcanized rubber sheet was prepared by press vulcanization at 0'C for 20 minutes. Further, put this in the gear oven for 150 min.
After heat treatment at ℃ for 4 hours, the physical properties of the vulcanized rubber were evaluated.

Examples 4 to 5, Comparative Example 3 The acrylic copolymer obtained in Synthesis Example 3 and acrylic rubber (2) [N]pot Al+-31 manufactured by Nippon Zeon Co., Ltd.] were roll-kneaded according to the formulation shown in Table 2, and 170
A vulcanized rubber sheet was prepared by press vulcanization at °C for 30 minutes. Furthermore, heat this in a gear oven at 150°C.
After heat treatment for 8 hours, the physical properties of the vulcanized rubber were evaluated.

Table 3 shows the unvulcanized comb physical properties and vulcanized physical properties of Examples 1 to 5 and Comparative Examples 1 to 3. Mooney viscosity is JIS K63
00. Vulcanized rubber physical properties were evaluated according to Tl5K6301. Gasoline resistance was evaluated by immersing the vulcanized rubber in Fuel Part C at 40° C. for 72 hours and then measuring the volume change rate. In addition, sour gasoline resistance is achieved by using vulcanized rubber with no fuel oil.
After immersion at 40° C. for 72 hours in a solution containing 100 parts by weight and 1 plate portion of lauroyl peroxide, the sample was evaluated by determining the volume change rate by /II. The glass transition temperature was measured using a differential scanning calorimeter (DS) using unvulcanized rubber as a sample.
C) at a heating rate of 10°C per minute.

<Effects of the Invention> As is clear from the above results, the present invention provides a vulcanizable rubber composition that has excellent gasoline resistance, sour gasoline resistance, and a good balance with cold resistance.

Patent applicant: Toso Corporation Procedural amendment Heisei 1 year April 20th

Claims (1)

[Claims] (1) (I) (A) Acrylic ester and/or methacrylic ester having the structure of the following formula (a) ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (a) (Here, R^1 is hydrogen or methyl (B) an acrylic copolymer consisting of a crosslinkable monomer; (II) Contains acrylic rubber and has a weight ratio of (I)/(II) of 95/5 to 5/9
5. A rubber composition characterized by: