JPH0249338B2 - GOMUSOSEIBUTSU - Google Patents

Description

[Detailed description of the invention]

The present invention relates to rubber compositions. More specifically, the present invention relates to a heat-resistant oil-based rubber composition that is a blend of an acrylic elastomer containing an alkoxy acrylate as a main component and a hydrin rubber and has excellent residual gasoline resistance. In recent years, with the progress of technological innovation in automobiles, the operating conditions for engines have become progressively more severe, and rubber parts around engines have come to be required to be more durable. Under these circumstances, NBR, which has traditionally met most of the demand for oil-resistant rubber, has an essential drawback because it contains double bonds in its main chain, and cannot withstand deterioration in harsh environments. More durable hydrin rubber has been adopted in fields that require fuel oil resistance. However, it has recently become clear that hydrin rubber undergoes significant softening and deterioration due to sour gas, which is a fuel oil that has become rancid due to the high temperatures around the engine. It has become common to use high-priced fluorocarbon rubber. The present inventor has conducted research to overcome the above-mentioned current situation, and has developed a new elastomer that can be used for oil seals, gaskets, gaskets, hoses, O-rings, and diaphragms as a fuel oil-resistant rubber with excellent durability (for example, (1983-123611) further conducted intensive studies on this problem and arrived at the present invention. The present invention provides fuel oil resistance and rancid gasoline resistance characterized by blending 10 parts by weight or more of an acrylic elastomer having 60 weight percent or more of alkoxy acrylate represented by the following formula (1) with 90 parts by weight or less of hydrin rubber. The objective is to obtain an excellent rubber composition. (1) CH ₂ = CHCOO-R ₁ -O-R ₂ (wherein, R ₁ is an alkylene group having 1 to 4 carbon atoms, R ₂
is an alkyl group or an alkoxyalkyl group having 1 to 4 carbon atoms) The present invention will be explained in more detail below. The hydrin rubber used in the present invention is usually
They are distributed on the market with abbreviations such as CHR, CO, CHC, and ECO, and are epichlorohydrin polymers, copolymers of epichlorohydrin and ethylene oxide, copolymers of epichlorohydrin and allyl glycidyl ether, epichlorohydrin, ethylene oxide, and allyl glycidyl ether. Copolymers with are commercially available, and any of them can be used. The acrylic elastomer must contain 60% by weight or more of alkoxyalkyl acrylate in the polymer composition; if the content is less than 60% by weight, the fuel oil resistance of the composition will decrease. The acrylic elastomer must be blended with hydrin rubber in an amount of 10 parts by weight or more; if it is less than 10 parts by weight, the sour gas resistance of the blend will be insufficient. A more preferable blend amount is 20 parts by weight or more, and it can be said that the feature of the present invention is that when this blend amount is exceeded, the blend has almost constant sour gas resistance. It is essential that the acrylic elastomer contains 60% by weight or more of alkoxyalkyl acrylate, but other monomers to be copolymerized must be contained in a manner that does not reduce the fuel oil resistance of the acrylic elastomer. It is obvious from the gist of the present invention that this is selected. For example, when producing the acrylic elastomer,

Since many vinylidene monomers having the formula can be copolymerized with alkoxyalkyl acrylate, specific examples thereof are listed below. An example of an alkoxyalkyl acrylate is one represented by the following formula _CH2 =CH-COO- _R1 -O- _R2 , where _R1 is an alkylene group having 1 to 4 carbon atoms, and _R2 is an alkylene group having 1 to 4 carbon atoms. represents an alkyl group or an alkoxy group. Specific examples include methoxyethyl acrylate, methoxymethyl acrylate, ethoxyethyl acrylate, butoxyethyl acrylate, methoxyethoxyethyl acrylate, and ethoxyethoxyethyl acrylate. Examples of vinylidene monomers include methyl acrylate, ethyl acrylate, and propyl acrylate for alkyl acrylates, and vinyl acetate, vinyl propionate, and vinyl butyrate for vinyl carboxylates. Ethylene can be copolymerized to improve cold resistance without impairing fuel oil resistance, and acrylonitrile can be copolymerized to further improve fuel oil resistance without impairing cold resistance. Furthermore, dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl maleate, etc. can also be copolymerized in the same manner as acrylic ester. In addition, when copolymerizing the acrylic elastomer, 50 parts by weight or less of a polyether or polyester plasticizer is added to 100 parts by weight of the monomer in order to improve processability and cold resistance, or It is also possible to add up to 50 parts by weight of a plasticizer to the polymer after polymerization. Examples of this plasticizer include polyesters of adipic acid and ethylene glycol or diethylene glycol for polyesters, and polyethylene oxide, polypropylene oxide, and random copolymers or block copolymers of these monomers for polyethers. . The molecular weight of these plasticizers is preferably 500 or more. The elastomer is further copolymerized with monomers represented by formulas (2) to (4) at a ratio of 10% by weight or less, making it vulcanizable with a vulcanizing agent used for ordinary acrylic elastomers, and improving practicality. can be increased. (In the formula, R ₃ is hydrogen or methyl group) (In the formula, R ₄ is a vinyl, allyl or methallyl group) (4) CH ₂ = CH-O-R ₅ (In the formula, R ₅ is CH ₂ Cl-CH ₂ - or CH ₂ Cl-CO-
Examples of compounds of formula (2) include glycidyl acrylate, glycidyl methacrylate, and compounds of formula (3).
Specific examples of formula (4) include vinyl glycidyl ether, allyl glycidyl ether, methallyl glycidyl ether, and examples of formula (4) include vinyl chloroacetate and 2-chloroethyl vinyl ether. These compounds of formulas (2) to (4) provide crosslinking points to the acrylic elastomer, and enable crosslinking of the composition with polyfunctional compounds other than peroxides (e.g., polyamines), and However, if added in excess, the crosslinking density will be too high and sufficient mechanical strength will not be obtained, so it is preferably 10% by weight or less. The copolymer used in the present invention can be obtained by copolymerizing monomers in approximately the above ratio by a method such as emulsion polymerization, bulk polymerization, or solution polymerization. Among these, emulsion polymerization is preferred. In order to obtain a copolymer containing diethylene units, polymerization may be carried out in an ethylene atmosphere pressurized as necessary. In any case, the polymerization is carried out in a manner analogous to ethylene-vinyl acetate copolymerization, and as such is uncharacteristic and does not require further elaboration. The copolymer was measured using a Mooney viscometer manufactured by Toyo Seiki Co., Ltd.
Results of measuring Mooney viscosity (ML ₁₊₄ ) at °C15
had values ranging from ~50. The method used to apply the blend of the present invention to materials for actual industrial parts and automobile parts is as follows:
Those normally used in the rubber industry are sufficient, and if necessary, carbon black, self-fillers, plasticizers, and processing aids are added to adjust the physical properties and processability, and a vulcanizing agent is added. The final product is produced by vulcanization and molding using the vulcanization method used in . Most of the vulcanizing agents listed above are normal hydrin rubber vulcanizing agents and acrylic rubber vulcanizing agents, such as peroxide, Eitan, trithiol triazine, and imidazole compounds.
It can be used depending on the compounds (2) to (4). The vulcanized rubber composition thus obtained has better sour gas resistance than conventional hydrin rubber, and can be used in industrial parts that require durability, especially automobile parts, such as hoses, seals, gaskets, O-rings, packings, etc. It has properties suitable for diaphragms, etc. The effectiveness of the present invention will be explained below using examples. Examples 1 to 4, Comparative Examples 1 to 3 530 g of polyvinyl alcohol (hereinafter abbreviated as PVA) and 21.6 g of sodium acetate were placed in a 40-liter autoclave.
2.16 kg of vinyl acetate and 2.0 kg of vinyl acetate were poured into the aqueous solution prepared by dissolving 16.2 kg of vinyl acetate.
- 8.6 kg of methoxyethyl acrylate, 108 g of glycidyl methacrylate and 22 g of allyl glycidyl ether were added and emulsified, and after purging the inside of the autoclave with nitrogen gas, ethylene monomer was pressurized from the top. Ethylene pressure is polymerization temperature 65℃, 55Kg/
It was adjusted so that it was cm ² . After that, a 1% aqueous solution of ammonium persulfate was added in several portions, and the
Stop polymerization for 3 hours, demonomerize, and remove borax.
A copolymer emulsion was coagulated using a % aqueous solution, dehydrated, and then rolled dried to obtain a copolymer. The yield of the copolymer was 10.4 kg, and the main composition of the obtained copolymer was 18 weight percent vinyl acetate, 76 weight percent 2-methoxyethyl acrylate, and 6 weight percent ethylene. The amount of epoxy groups due to copolymerized glycidyl methacrylate and allyl glycidyl ether as crosslinking points was 92 mmol/Kg. This copolymer is designated as A. This copolymer was prepared using an 8-inch roll at a roll temperature of 40°C according to the formulation shown in Table 1.
First, copolymer A and hydrin rubber were wrapped together, cut and turned for 3 minutes, rolled through 6 times, kneaded, press-cured at 160°C for 30 minutes, and then heated in a gear oven at 150°C. After vulcanization for 8 hours, a 15 cm square and 2 mm thick vulcanized plate was prepared and its physical properties were measured. The results are shown in Table-1. Hydrin rubber (Hydrin200 manufactured by Gutstoritsi,
Table 1 for Gechron3100 manufactured by Nippon Zeon Co., Ltd.
In the same manner as in Example 1 using the formulation shown in
Kneading and vulcanization were performed, and physical properties were measured. The results are shown in Table-1. Physical property tests were conducted in accordance with JIS K6301 unless otherwise specified. For the fuel oil resistance test, a post-vulcanized No. 3 dumbbell was immersed in fuel oil C described in JIS K6301 at 40°C for 70 hours according to the immersion test method of JIS K6301, and after immersion, it was taken out. Physical properties were measured within 30 minutes. The sour gas used in the sour gas resistance test was prepared by dissolving 1% by weight of lauroyl peroxide (LPO) in the above fuel oil c, and immediately used for the test after dissolving. The immersion was conducted in accordance with the immersion test method of JIS K6301. After immersion at 40°C for 70 hours, the sour gas was replaced with freshly prepared sour gas three times, and 210 hours after the start of immersion, the No. 3 dumbbell of the post-vulcanized product was taken out and its physical properties were measured within 30 minutes. The monomers used to provide crosslinking points (glycidyl methacrylate, allyl glycidyl ether) are small components of the copolymer, so they are ignored when analyzing the main composition, and each composition is The amount of epoxy groups was calculated and used as a measure of the actual amount of crosslinking points.

【table】

[Table] Examples 5 to 7 Comparative Examples 4 to 6 An aqueous solution prepared by dissolving 530 g of PVA and 21.6 g of sodium acetate to a total weight of 16.2 g was put into a 40-sized autoclave, and while stirring, the monomer mixture solution of 10.8 g was added. Kg and glycidyl methacrylate 70
g and 70 g of allyl glycidyl ether were added and emulsified, and after purging the inside of the autoclave with nitrogen gas, ethylene monomer was pressurized from the top. Ethylene pressure was adjusted so that the polymerization temperature was 65° C. and 55 Kg/cm ² . Thereafter, a 1% aqueous solution of ammonium persulfate was added several times in portions, the polymerization was stopped after about 10 hours, and the copolymer emulsion was sequentially demonomerized, coagulated with a 3% aqueous borax solution, and dehydrated, followed by roll drying. , the copolymer shown below was obtained.

【table】

[Table] This polymer and Hydrin200 were rolled into an 8-inch roll at 50°C.
to obtain a vulcanized sheet using the same blending method and sample preparation method as in Examples 1 to 4.
Tests were conducted in the same manner as Examples 1-4. The results are shown in Table-2.

【table】

[Table] Example 8 2 kg of water, 50 g of partially saponified poval, and 2 g of sodium acetate were placed in the autoclave prepared in Example 8 and dissolved with stirring. While stirring, a premixed solution of 900 g of methoxyethyl acrylate, 100 g of acrylonitrile, 10 g of glycidyl methacrylate, and 5 g of allylglycidyl acrylate was gradually added and emulsified, and the space inside the autoclave was completely replaced with nitrogen gas. The internal temperature was raised to 55°C, and 30g of a 10% aqueous solution of ammonium persulfate was added to initiate polymerization. After about 8 hours, it was confirmed that the polymerization rate had reached about 100%, and the emulsion after the polymerization was taken out was coagulated with a 3% borax aqueous solution, and after being lightly washed with water, it was dried at 80°C to obtain copolymer H. Ta. The main composition was 90% by weight of methoxyethyl acrylate, 10% by weight of acrylonitrile, and the amount of epoxy groups was 106 mmol/Kg. Copolymer H and Hydrin 200 were blended in equal amounts in the same manner as in Examples 1 to 4, and samples were prepared and tested in the same manner as in Examples 1 to 4 using the formulation shown in Table 3. However, only for the sour gas resistance test, the liquid exchange period was extended to 5 times, or 350 hours. The results are shown in Table-3.

【table】

[Table] Comparative Examples 7, 8 Hydrin200, Gechron3100, Examples 1 to 8
The mixture was kneaded and vulcanized according to the formulation shown in Table 3 in the same manner as in 4 to obtain a vulcanized rubber sheet. However, the post-vulcanization time for Hydrin200 is 150℃ for 4 hours,
For Gechron3100, the temperature was 150°C for 2 hours. All tests were conducted in the same manner as in Example 8. The results are shown in Table-3. 2 kg of water, 50 g of partially saponified poval, and 2 g of sodium acetate were placed in the autoclave of Example 9 5 and dissolved with stirring. While stirring, a premixed solution of 700 g of methoxyethyl acrylate, 300 g of acrylonitrile, 7 g of glycidyl methacrylate, and 200 g of polyester was gradually added and emulsified. After the space inside the autoclave was completely replaced with nitrogen gas, the internal temperature was lowered. The temperature was raised to 55°C, and 30 g of a 10% aqueous solution of ammonium persulfate was added to initiate polymerization. After about 10 hours, it was confirmed that the polymerization rate was approximately 100%, and the emulsion after the completion of polymerization was taken out, and the polymer components were coagulated with a 3% aqueous borax solution, washed lightly with water, and dried at 80°C to obtain copolymer K. The main composition of the copolymer K excluding the plasticizer was 70% by weight of methoxyethyl acrylate and 30% by weight of acrylonitrile, and the amount of epoxy groups was 53 mmol/Kg based on the portion excluding the plasticizer. Copolymer K was blended with Hydrin 200 in the same manner as in Examples 1 to 4, and samples were prepared in the same manner as in Examples 1 to 4 using the formulation shown in Table 4.
Press vulcanization was performed at 160°C for 30 minutes. No post-vulcanization was performed. Various tests were conducted on this vulcanizate in the same manner as in Example 8, and the results are shown in Table 4. Example 10 1.5 kg of water, 50 g of partially saponified poval, and 2 g of sodium acetate were placed in the autoclave of Example 10 and dissolved therein with stirring. Add 600 g of methoxyethyl acrylate and 400 g of dimethoxyethyl fumarate while stirring.
Gradually add a premixed solution of 15g of allyl glycidyl ether, and 200g of polyester to emulsify it. After completely replacing the space inside the autoclave with nitrogen gas, set the internal temperature to 55℃ and add 30g of a 10% aqueous solution of ammonium persulfate. was added to start polymerization. After about 10 hours, confirm that the polymerization rate is almost 100% and take out the emulsion after polymerization.
% borax aqueous solution, washed lightly with water, and dried at 80°C to obtain copolymer L. The main composition of Copolymer L excluding the plasticizer was 62% by weight of methoxyethyl acrylate and 38% by weight of dimethoxyethyl fumarate, and the amount of epoxy groups was 130 mmol/Kg based on the portion excluding the plasticizer. Copolymer L was prepared using the formulation shown in Table 4.
Table 4 shows the results of blending with Hydrin 200 and testing in the same manner as in Example 9.

[Table] Example 11 An aqueous solution prepared by dissolving 530 g of PVA and 21.6 g of sodium acetate to a total weight of 16.2 kg was put into a 40-sized autoclave, and while stirring, vinyl acetate was added.
After adding 2.5 kg and 8.3 kg of 2-methoxyethyl acrylate and emulsifying the autoclave, the inside of the autoclave was purged with nitrogen gas, and ethylene monomer was injected from the top. Ethylene pressure was adjusted so that the polymerization temperature was 55° C. and 45 Kg/cm ² . Thereafter, a 1% aqueous solution of ammonium persulfate was added in several portions to stop the polymerization in about 10 hours, and after demonomerization, the copolymer emulsion was coagulated and dehydrated with a 3% aqueous borax solution, followed by roll drying. A copolymer was obtained. The yield of the copolymer was 10.6 kg, and the composition of the obtained copolymer was 20% by weight of vinyl acetate, 2% by weight of vinyl acetate,
-77 weight percent methoxyethyl acrylate and 3 weight percent ethylene. This copolymer is designated as M. For this polymer, Tables 1 to 4 were prepared using the following formulations.
A vulcanized rubber sheet was obtained by blending and kneading in the same manner as above, and by press vulcanization at 160°C for 30 minutes. Hydrin200 50 Copolymer M 50 FEF carbon 40 Heavy carbon 20 Stearic acid 1 Polyester plasticizer 5 Dicumyl peroxide 1.8 Triallylisocyanuride 1 Lead Red 5 Ethylenethiourea 1.2 Table 5 shows the test results for sulfuric acid. show. The same test method as in Examples 1 to 4 was used.

[Table] Examples 12 to 14 Equivalent blends of copolymer A and Hydrin 200 were kneaded according to the recipe shown in Table 6, and vulcanized rubber sheets were prepared and tested in the same manner as in Examples 1 to 4.

【table】

Claims (1)

[Scope of Claims] A rubber composition obtained by blending 10 parts by weight or more of an acrylic elastomer containing 60% by weight or more of an alkoxyalkyl acrylate represented by the following formula (1) with 90 parts by weight or less of hydrin rubber. (1) CH ₂ = CHCOO-R ₁ -O-R ₂ (wherein, R ₁ is an alkylene group having 1 to 4 carbon atoms, R ₂
is an alkyl group or alkoxyalkyl group having 1 to 4 carbon atoms)