JPS638128B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention contains a copolymer mainly composed of vinyl carboxylate and alkoxyalkyl acrylate and a crosslinking agent, and through crosslinking, it has both mechanical properties and durability such as heat resistance, oil resistance, and weather resistance. The present invention relates to rubbery compositions that provide rubber. Rubber parts used as automobile parts and other mechanical parts are required to have durability such as heat resistance, oil resistance, and weather resistance in addition to mechanical properties such as tensile strength and elongation. There is a growing demand for Traditionally, chloroprene rubber and nitrile rubber have been used for rubber parts that generally require oil resistance, but they also have heat resistance, weather resistance (ozone resistance)
As the demands for these properties become more severe, acrylic rubber and epichlorohydrin rubber, which have excellent properties, are being used. However, acrylic rubber has a disadvantage in that it has a high swelling property with respect to fuel oil and cannot be used for parts particularly requiring severe fuel oil resistance. On the other hand, epichlorohydrin rubber also has the disadvantage of having low bending resistance and being softened by heat. As described above, the reality is that rubber materials that have both mechanical properties and durability have not always been available. In view of the above points, the present inventors conducted research in search of a rubber material that is in harmony with mechanical properties and durability. As a result, the present inventors developed a cross-linked polymer mainly composed of vinyl carboxylate and alkoxyalkyl acrylate. By doing so, heat resistance, oil resistance (especially fuel oil resistance),
The present invention was completed based on the finding that a rubber with excellent durability such as weather resistance and good mechanical properties can be obtained. That is, the rubber composition of the first invention by the present inventors contains, as polymerized units, 15 to 40 parts by weight of vinyl carboxylate represented by the following formula () and an alkoxyalkyl acrylate represented by the following formula (). 60-85
It is characterized by containing a copolymer and a crosslinking agent having a composition of 0 to 15 parts by weight of ethylene and 100 parts by weight in total of these components. In addition, the rubber composition of the second invention by the present inventors contains 15 to 40 parts by weight of vinyl carboxylate represented by the following formula () as a polymerization unit, and a rubber composition according to the following formula ().
The alkoxyalkyl acrylate represented by
60 to 85 parts by weight, 0 to 15 parts by weight of ethylene, 100 parts by weight in total of these components, and the following formula () ~
It is characterized by containing a copolymer having a composition of one or more of the components represented by () in a total of up to 5 parts by weight, and a crosslinking agent. () RCOO-CH=CH ₂ (in the formula, R is an alkyl group having 1 to 4 carbon atoms), () CH ₂ =CHCOO-R ₁ -O-R ₂ (in the formula, R ₁ is an alkyl group having 1 to 4 carbon atoms) alkylene group,
_R2 is an alkyl group or alkoxyalkyl group having 1 to 4 carbon atoms), () (In the formula, R ₃ is a hydrogen atom or a methyl group) () (In the formula, R ₄ is a vinyl, allyl or methallyl group). The present invention will be explained in more detail below. The copolymer in the present invention contains 15 to 40 parts of vinyl carboxylate (parts by weight; the same shall apply hereinafter), 60 to 85 parts of alkoxyalkyl acrylate, and 0 to 15 parts of ethylene as polymerized units. Included for a total of 100 parts of the ingredients. Vinyl carboxylate is represented by the formula R-COO CH=CH ₂ () (R represents an alkyl group having 1 to 4 carbon atoms), and specifically includes vinyl acetate, vinyl propionate, There is vinyl butyrate, and in the case of vinyl caproate in which the group R has 5 carbon atoms, sufficient oil resistance cannot be obtained. If the amount of vinyl carboxylate is less than 15 parts, the mechanical properties of the composition deteriorate and are unsatisfactory. Moreover, if it exceeds 40 parts, cold resistance will be insufficient. Alkoxyalkyl acrylate is represented by the formula _CH2 = _CHCOOR1 -O- _R2 ...(), where _R1 is an alkylene group having 1 to 4 carbon atoms, and _R2 is an alkyl group having 1 to 4 carbon atoms. Or represents an alkoxy group. Specific examples include methoxyethyl acrylate, methoxymethyl acrylate, ethoxyethyl acrylate, butoxyethyl acrylate, methoxyethoxyethyl acrylate, and ethoxyethoxyethyl acrylate. These alkoxyalkyl acrylates are contained in the composition in an amount of 60 to 85 parts. If it is less than 60 parts, oil resistance is insufficient, and
If the amount exceeds 85 parts, the mechanical properties of the composition deteriorate and are unsatisfactory. Ethylene is not essential to the copolymer of the present invention, but is added as necessary to improve cold resistance, and the amount used is up to 15 parts. If it exceeds 15 parts, fuel oil resistance will decrease. It is particularly preferred that the amount of ethylene is 10 parts or less. Specific examples of the compound of the formula () used in the second invention include glycidyl acrylate and glycidyl methacrylate; specific examples of the compound of the formula () include vinyl glycidyl ether, allyl glycidyl ether, methallyl glycidyl ether, and the formula ( ) Examples include vinyl chloroacetate and 2-chloroethyl vinyl ether.
These compounds of formulas () to () provide crosslinking points to the copolymer of the present invention, and polyfunctional compounds other than peroxides (e.g., polyamines) enable crosslinking of the composition, and thermal Crosslinking in air is also possible, but if too much is added, the crosslinking density will be too high and sufficient mechanical strength will not be obtained. It is necessary to keep it to 5 parts 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 ethylene 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 not distinctive and therefore requires no further elaboration. The Mooney viscosity (ML ₁₊₄ ) of the copolymer was measured at 100℃ using a Mooney viscometer manufactured by Toyo Seiki Co., Ltd., and the result was 35 to 50.
had a range of values. For the copolymer obtained as above,
Crosslinking is carried out by adding 0.3 to 10% (weight %; the same shall apply hereinafter), preferably 0.5 to 5%, of a crosslinking agent. 0.3%
If it is less than 10%, crosslinking will not be carried out sufficiently, and if it exceeds 10%, it will cause overcrosslinking or bloom scorch. Examples of the crosslinking agent include benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane,
n-butyl-4,4-bis(t-butylperoxy)valerate, dicumyl peroxide, di-t-butylperoxy-diisopropylbenzene, 2,5-dimethyl-2,5-di(t-butyl) peroxy)hexane, 2,5-dimethyl-2,
A peroxide such as 5-di(t-butylperoxy)hexyne-3 is used. Also, the above formula () ~
For a copolymer containing the compound () as a structural unit, an epoxide ring-opening compound can be used as a crosslinking agent. Examples include tetraethylenepentamine, hexaethylenetetramine, hexamethylenediamine carbamate, N,
Polyamines such as N'-dicinnamylidene-1,6-hexanediamine; ammonium benzoate,
Examples include thermally decomposable ammonium salts such as ammonium citrate and ammonium tartrate. These crosslinking agents can also be used in combination with metal salts of dithiocarbamic acids, thiurams, sulfur, and the like. In addition to the above-mentioned crosslinking agent, the rubber composition of the present invention contains carbon black, anhydrous silicic acid, hydrous silicic acid, hard clay, surface-treated calcium carbonate,
It is preferred to add a reinforcing agent such as microtalc in an amount of 10 to 200 parts, particularly 30 to 100 parts, per 100 parts of the polymer. In addition, lubricants such as stearic acid and its metal salts, fillers such as soft clay, light calcium carbonate, heavy calcium carbonate, and talc are used to adjust pressurability and other physical properties; petroleum-based softeners, synthetic polyesters, A plasticizer such as a polyoxyethylene ester or ether plasticizer; and an anti-aging agent may be appropriately selected and used. As the anti-aging agent, all those commonly used for the purpose of stabilizing high molecular compounds can be used. For example, amine anti-aging agents such as N-phenyl-N'-isopropyl-p-phenylenediamine, phenyl-α-naphthylamine, acrylic esters having an aromatic amine moiety (for example, Nokrac G manufactured by Ouchi Shinko Kagaku Co., Ltd.) ―
1), trimethyldihydroquinoline polycondensate, etc.;
Phenolic anti-aging agents, such as 3,5-T
-Butyl-4-hydroxytoluene, 1,3,5
-Trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate ,
4,4'-thiobis(6-t-butyl-3-methylphenol) etc.; dithioic acid type anti-aging agents such as nickel dibutyl dithiocarbamate, dilauryl dithiopropionate etc.; phosphoric acid ester type anti-aging agents such as tris (nonylphenyl) phosphite and the like can be used. These anti-aging agents can be used alone or in combination of two or more. In order to add and blend various additives to the above-mentioned copolymer, any kneading method normally used in the rubber industry may be used. If necessary, it is also possible to adopt the so-called wet masterbatch method, in which carbon black and other additives are added to the polymer dispersion after the polymerization reaction to obtain the copolymer, and the finished product is dried. It is. The crosslinking agent for the rubbery composition of the present invention can be obtained by crosslinking a mixture obtained by kneading the above copolymer and additives with a crosslinking agent using any vulcanization method commonly used in the rubber industry. Crosslinking is usually achieved by holding at a temperature of 120 to 200°C for about 2 to 200 minutes, although it varies depending on the type and amount of crosslinking agent used. The copolymers of the present invention can be crosslinked with various crosslinking agents at widely different crosslinking rates, and sulfur can also be used in combination. Therefore, in obtaining the rubbery composition of the present invention by crosslinking, EPDM, NBR, chloroprene rubber, natural rubber, styrene-butadiene rubber, butadiene rubber, butyl rubber, isoprene rubber, etc. are added to the above copolymer. Rubber polymers can also be blended, thereby improving the oil and weather resistance of these rubber polymers while maintaining their mechanical properties at practical levels. The rubber-like composition of the present invention obtained in this manner is molded by any rubber molding method before or simultaneously with crosslinking to obtain oil resistance, heat resistance, and weather resistance in addition to mechanical properties. Applications, such as automobile rubber parts (especially rubber parts with strict fuel oil resistance requirements, such as fuel oil hoses),
Rubber parts suitable for industrial parts used in contact with high-temperature lubricating oil can be obtained. The present invention will be explained in more detail below using Examples. The compositions of the copolymers in the examples were determined by the following general compositional analysis. That is, a polymer solution is prepared, and a caustic soda aqueous solution is added to saponify the polymer. After saponification,
The amount of -COONa in the saponified solution was determined by potentiometric titration, and the carboxylic acids and alkoxy alcohols liberated in the saponified solution were completely separated from the saponified polymer. Carboxylic acids were determined by titration, and alcohols were determined by gas chromatography. Each is quantified and converted to determine the vinyl carboxylate and alkoxyalkyl acrylate contents in the polymer. Also, if it contains compounds of formulas () to (), the formula ()
The compounds of and () are determined by epoxy group assay. Finally, the amount of the above-mentioned components is subtracted from the amount of the sample polymer, and the remainder is defined as the ethylene content. Example 1 530 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.
-Add 8.64Kg of methoxyethyl acrylate and emulsify it. After purging the inside of the autoclave with nitrogen gas, ethylene monomer is injected from the top. Ethylene pressure is adjusted so that the polymerization temperature is 65°C and 55Kg/cm ² . After that, a 1% aqueous solution of ammonium persulfate was added in several portions, and the polymerization was stopped in about 10 hours.
A copolymer was obtained by removing the monomer, coagulating the copolymer emulsion with a 3% aqueous solution of borax, and dehydrating, followed by roll drying. . The yield of the copolymer was 10.4 kg, and the composition of the obtained copolymer was 18 parts by weight of vinyl acetate, 76 parts by weight of 2-methoxyethyl acrylate, and 6 parts by weight of ethylene. This copolymer was kneaded using an 8-inch roll at a roll temperature of 40°C, and press-cured at 160°C for 30 minutes according to the following formulation. A vulcanized plate was prepared and its physical properties were measured. The results are shown in Table-1.

[Table] Comparative Example 1 Epichlorohydrin rubber (trade name "Hydrin 200" manufactured by Gutsudoritsu) was treated in the same manner as in Example 1 using the following formulation.
Kneading and vulcanization were performed, and physical properties were measured. The results are shown in Table-1.

[Table] Comparative Example 2 Acrylic rubber (trade name "AR-31" manufactured by Nippon Zeon Co., Ltd.) was kneaded and vulcanized in the same manner as in Example 1 using the following formulation, and the physical properties were measured. I did this. The results are shown in Table-1.

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[Table] Examples 2 to 4 Comparative Example 3 530 g of PVA, 21.6 g of sodium acetate, 32.4 g of Rongarit, 1.08 g of ethylenediaminetetraacetic acid, and 0.54 g of ferrous sulfate were dissolved in a 40-liter autoclave to give a total weight of 16.2 kg. 2-Methoxyethyl acrylate 8.64 kg was added to each aqueous solution while stirring, and emulsified by adding 2.16 kg of vinyl carboxylate of the types shown in Table 2 below. After purging the inside of the autoclave with nitrogen gas, when the temperature reached 45°C, 8.64 kg of 2-methoxyethyl acrylate was added. A mixed solution of Kg and 162 g of glycidyl methacrylate and a 1% aqueous solution of ammonium persulfate are added dropwise from separate injection ports over a period of 8 to 16 hours to advance polymerization.
After the polymerization was completed, the monomer was removed, and the polymer emulsion was coagulated and dehydrated with an aqueous borax solution, followed by roll drying to obtain a copolymer. The composition and yield of the obtained copolymer are shown in Table 2. These copolymers were kneaded using an 8-inch roll at a roll temperature of 50℃ using the following formulation, and then press-cured at 160℃ for 30 minutes to form a 15cm square, 2mm thick sheet. A vulcanized plate was produced and its physical properties were measured. The results are shown in Table-2.

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[Table] Examples 5 to 8 Comparative Examples 4 to 6 Dissolve 530 g of PVA, 21.6 g of sodium acetate, 32.4 g of Rongarit, 1.08 g of ethylenediaminetetraacetic acid, and 0.54 g of ferrous sulfate in a 40-sized autoclave to give a total weight of 16.2 kg. Pour in the aqueous solution prepared above, add vinyl acetate while stirring to emulsify it, and after purging the inside of the autoclave with nitrogen gas, if ethylene is to be copolymerized, ethylene monomer is pressure-injected from the top. In each example, the ethylene pressure is adjusted to different pressures in the range of 20 to 150 Kg/cm ² at a polymerization temperature of 45°C. After that, 2-methoxyethyl acrylate and glycidyl methacrylate 162
Polymerization is proceeded by adding a mixed solution of 1.g and a 1% aqueous solution of ammonium persulfate dropwise from separate injection ports over a period of 8 to 16 hours. The total weight of vinyl acetate and 2-methoxyethyl acrylate is 10.8 kg. After the polymerization was completed, the monomer was removed, and the polymer emulsion was coagulated and dehydrated with an aqueous borax solution, followed by roll drying to obtain a copolymer. The composition and yield of the obtained copolymer are shown in Table 3. These copolymers were kneaded using an 8-inch roll at a roll temperature of 50° C. according to the following formulation to prepare a vulcanized plate of 15 cm parallel and 2 mm thick, and its physical properties were measured. The results are shown in Table-3.

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[Table] Examples 8 to 11 Comparative Example 7 530 g of PVA, 21.6 g of sodium acetate, 32.4 g of Rongarit, 1.08 g of ethylenediaminetetraacetic acid, and 0.54 g of ferrous sulfate were dissolved in a 40-sized autoclave to give a total weight of 16.2 kg. The prepared aqueous solution is poured into the autoclave, and 2.7 kg of vinyl acetate is added while stirring to emulsify it. After purging the inside of the autoclave with nitrogen gas, ethylene monomer is injected from the top. Ethylene pressure is adjusted to 50 Kg/cm ² at a polymerization temperature of 55°C. Thereafter, a mixed solution of 8.1 kg of 2-methoxyethyl acrylate and different amounts of glycidyl methacrylate in the range of 60 to 900 g each, and a 1% aqueous solution of ammonium persulfate were added dropwise from separate injection ports over a period of 8 to 10 hours to polymerize. proceed. After the polymerization was completed, the monomer was removed, and the polymer emulsion was coagulated and dehydrated with an aqueous borax solution, followed by roll drying to obtain a copolymer. The composition and yield of the obtained copolymer are shown in Table 4. These copolymers were kneaded using 8-inch rolls at a roll temperature of 50°C according to the following formulation. Press vulcanization was performed at 160° C. for 31 minutes, and post-vulcanization was performed at 150° C. for 15 hours in a gear oven to produce a vulcanized plate of 15 cm square and 2 mm thick, and its physical properties were measured. The results are shown in Table 4.

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[Table] Examples 12 to 17 The copolymer of Example 9 was prepared using an 8-inch roll according to the formulation shown in Table 6, and the roll temperature was
Kneading was carried out at 40°C and vulcanization was performed under the vulcanization conditions shown in Table 6 to prepare a 15 cm square and 2 mm thick vulcanized plate, and its physical properties were measured. The results are shown in Table-7.

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[Table] Example 18 Comparative Example 8 An aqueous solution prepared by dissolving 530 g of PVA, 21.6 g of sodium acetate, 32.4 g of Rongalit, 1.08 g of ethylenediaminetetraacetic acid, and 0.54 g of ferrous sulfate in a 40-liter autoclave to give a total weight of 16.2 kg. was added, and while stirring, a predetermined amount of vinyl acetate was added to emulsify it, and the inside of the autoclave was purged with nitrogen gas. Thereafter, predetermined amounts of 2-methoxyethyl acrylate and a 1% aqueous solution of ammonium persulfate were added dropwise from separate injection ports over a period of 10 hours to advance polymerization. After the polymerization was completed, the monomer was removed, and the polymer emulsion was coagulated and dehydrated with an aqueous borax solution, followed by roll drying. The composition of the copolymer obtained from the charge of 2.0 kg of vinyl acetate and 9.5 kg of 2-methoxyethyl acrylate was 15 parts by weight of vinyl acetate and 85 parts by weight of 2-methoxyethyl acrylate. In addition, for preparing 1.5 kg of vinyl acetate and 10.0 kg of 2-methoxyethyl acrylate, 10 parts by weight of vinyl acetate, 2-methoxyethyl acrylate
90 parts by weight of copolymer was obtained. This copolymer was kneaded using an 8-inch roll at a roll temperature of 50°C, and press vulcanized at 170°C for 10 minutes, using the following formulation.
A vulcanized plate of 15 cm square and 2 mm thick was prepared, and after vulcanization was performed in a gear oven at 150°C for 16 hours, the physical properties were measured. The results are shown in Table-8.

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Claims (1)

[Claims] 1. As polymerization units, 15 to 40 parts by weight of vinyl carboxylate represented by the following formula (), 60 to 85 parts by weight of alkoxyalkyl acrylate represented by the following formula (), and 0 parts by weight of ethylene. A rubber-like composition comprising a copolymer having a composition of ~15 parts by weight, a total of 100 parts by weight of these components, and a crosslinking agent. () RCOO-CH=CH ₂ (in the formula, R is an alkyl group having 1 to 4 carbon atoms), () CH ₂ =CHCOO-R ₁ -O-R ₂ (in the formula, R ₁ is an alkyl group having 1 to 4 carbon atoms) alkylene group,
R ₂ is an alkyl group or alkoxyalkyl group having 1 to 4 carbon atoms) 2 As a polymerization unit, 15 to 40 parts by weight of vinyl carboxylate represented by the following formula (), and an alkoxyalkyl acrylate represented by the following formula () 60 to 85 parts by weight, 0 to 15 parts by weight of ethylene, a total of 100 parts by weight of these components, and a total of 5 parts by weight of one or more of the components represented by the following formulas () to (), A rubber composition comprising a copolymer having the composition and a crosslinking agent. () RCOO-CH=CH ₂ (in the formula, R is an alkyl group having 1 to 4 carbon atoms), () CH ₂ =CHCOO-R ₁ -O-R ₂ (in the formula, R ₁ is an alkyl group having 1 to 4 carbon atoms) alkylene group,
_R2 is an alkyl group or alkoxyalkyl group having 1 to 4 carbon atoms), () (In the formula, R ₃ is a hydrogen atom or a methyl group), () (In the formula, R ₄ is a vinyl, allyl or methallyl group).