JPH0688005A - Rubber composition - Google Patents

Abstract

PURPOSE:To obtain a rubber composition having a low strength of peeling from metal and not firmly fixed to metal by adding a small amount of a phosphoric ester plasticizer to an elastomer containing an unsaturated carboxylic acid ester as a comonomer. CONSTITUTION:The composition is prepared by adding 1-50 pts.wt. phosphoric ester plasticizer and optionally a phosphorus compound to 100 pts.wt. elastomer comprising an unsaturated carboxylic acid ester such as an acrylic rubber, an acrylic acid ester/nitrile copolymer rubber, its hydrogenate or an ethylene/ acrylate copolymer rubber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition which is excellent in oil resistance and cold resistance and which does not adhere to the surface when contacted with a metal.

[0002]

2. Description of the Related Art Conventionally, in applications such as oil filter packings and oil hoses for automobiles, a rubber member and a metal are in contact with each other and exposed to a considerably high temperature.
If it is used for a long time in that state, the phenomenon that rubber adheres to the metal surface may occur. This phenomenon is particularly remarkable in an elastomer containing an unsaturated carboxylic acid ester as a polymerization component. Various studies have been made on such a rubber sticking phenomenon, and as a countermeasure against this, a polyfunctional monomer is coated on the rubber surface,
A method of irradiating rubber with ultraviolet rays is being studied. However, these methods are complicated in operation and are not always effective for rubber members having various shapes. The elastomer containing the unsaturated carboxylic acid ester as a polymerization component has an excellent balance of physical properties required for a rubber member for automobiles, such as oil resistance, cold resistance, and heat resistance, and is used in a wide range of applications. Therefore, improvement of the adhesion to this metal has been demanded.

[0003]

DISCLOSURE OF THE INVENTION In these studies, the present inventors have found that a rubber composition obtained by blending an elastomer containing an unsaturated carboxylic acid ester as a polymerization component with a phosphate ester plasticizer is It was found that the peeling strength between the metal and the rubber layer is low, and there is almost no sticking of the rubber to the metal surface, which is an unexpected effect, and the present invention has been completed. An object of the present invention is to provide a rubber composition which is excellent in oil resistance, cold resistance, heat resistance and the like, and which does not particularly cause a sticking phenomenon on a metal surface.

[0004]

The above object is to add 1 to 50 parts by weight of a phosphoric acid ester plasticizer to 100 parts by weight of an elastomer containing an unsaturated carboxylic acid ester as a polymerization component.
This is achieved by a rubber composition containing 1 part by weight of a phosphorus-containing compound, and a vulcanized product thereof.

The elastomer containing the unsaturated carboxylic acid ester used in the present invention as a polymerization component is
Acrylic rubber, unsaturated nitrile-unsaturated carboxylic acid ester-conjugated diene copolymer, hydrogenated unsaturated nitrile-
Examples thereof include unsaturated carboxylic acid ester-conjugated diene-based copolymers and ethylene-acrylate-based copolymers.

The acrylic rubber of the present invention is an elastomer comprising an alkyl acrylate and / or an alkoxyalkyl acrylate monomer, a monoethylenically unsaturated monomer copolymerizable therewith and a crosslinking monomer. The alkyl acrylate monomers used in this production are methyl acrylate, ethyl acrylate,
Examples include propyl acrylate, butyl acrylate, hexyl acrylate, cyclohexyl acrylate, and the like. Further, examples of the alkoxyalkyl acrylate monomer include methoxymethyl acrylate, methoxyethyl acrylate, butoxyethyl acrylate and the like. The monoethylenically unsaturated monomer copolymerizable with these is an optional component used depending on the required physical properties of the rubber composition, and specific examples thereof include acrylonitrile, vinyl acetate, styrene, acrylamide, vinyl chloride and vinylidene chloride. And so on. The cross-linking monomer is not particularly limited, and an active chlorine group, an epoxy group, a cross-linking point,
It is appropriately selected from unsaturated groups, carboxyl groups and the like.

The unsaturated nitrile constituting the unsaturated nitrile-unsaturated carboxylic acid ester-conjugated diene copolymer of the present invention includes acrylonitrile and methacrylonitrile, and the conjugated diene includes 1,3-butadiene,
2,3-dimethylbutadiene, isoprene, 1,3-pentadiene and the like can be mentioned. Examples of the unsaturated carboxylic acid ester copolymerized with these monomers include methyl acrylate, butyl acrylate, dimethyl maleate, diethyl fumarate, di-n-butyl fumarate, and di-n-itaconate.
-Alkyl esters of unsaturated carboxylic acids such as butyl; alkoxyalkyl esters of unsaturated carboxylic acids such as methoxyacrylate, ethoxyethyl acrylate, methoxyethoxyethyl acrylate; α and β-cyanoethyl acrylate, α, β and γ-cyanopropyl Acrylate, cyanobutyl acrylate,
Acrylate having cyanoalkyl group such as cyanooctyl acrylate; Acrylate having hydroxyalkyl group such as 2-hydroxyethyl acrylate and hydroxypropyl acrylate; Acrylate having amino group such as dimethylaminomethyl acrylate and diethylaminoethyl acrylate; Trifluoro Included are acrylates having fluoroalkyl groups such as ethyl acrylate, pentafluoropropyl acrylate, dodecafluoroheptyl acrylate, and the like. In addition to these monomers, a part of the unsaturated monomer,
It may be substituted with a vinyl-based monomer such as styrene and vinyl pyridine, or a non-conjugated diene such as vinyl norbornene, dicyclopentadiene, and 1,4-hexadiene within a range not impairing the gist of the present invention.

Specific examples include butadiene-methyl acrylate-acrylonitrile copolymer rubber, butadiene-butyl acrylate-acrylonitrile copolymer rubber, butadiene-itaconic acid di-n-butyl-acrylonitrile copolymer rubber. The amount of bound unsaturated nitrile in the copolymer rubber is usually 5 to 60% by weight, preferably 10 to 50% by weight in view of the requirement for oil resistance.

The hydrogenated unsaturated nitrile-unsaturated carboxylic acid ester-conjugated diene-based copolymer of the present invention can be prepared by using the above-mentioned unsaturated nitrile-unsaturated carboxylic acid ester-conjugated diene-based copolymer by a conventional method (for example, Kosho 60-582
No. 42, Japanese Patent Publication No. 62-61045, etc.), the conjugated diene unit portion in the copolymer is hydrogenated.

The ethylene-acrylate copolymer of the present invention is typically a copolymer of ethylene, methyl acrylate and a crosslinking monomer.

The vulcanizing agent used for each of these elastomers is not particularly limited and is appropriately selected depending on the required physical properties. Typical examples are organic peroxide-based vulcanizing agents and sulfur-based vulcanizing agents. In the case of acrylic rubber, a vulcanizing agent is selected according to the type of the crosslinking monomer. For example, when the crosslinking monomer is an epoxy group-containing monomer, a quaternary ammonium salt, dithiocarbamate, or the like is used. Further, in the case of an active chlorine group-containing monomer, a triazine compound or Soap-Sulfur type vulcanizing agent is used.

The phosphate plasticizer, which is another constituent of the present invention, is often used as a plasticizer in acrylonitrile-butadiene copolymers and the like. Examples thereof include trimethyl phosphate, tributyl phosphate, tri- (2-ethylhexyl) phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, alkylallyl phosphate and the like. These are added in an amount of 1 to 50 parts by weight, preferably 3 to 30 parts by weight, based on 100 parts by weight of the elastomer. When the amount is 3 parts by weight or less, the effect of improving the sticking property is low, and when the amount is 50 parts by weight or more, the strength and physical properties of the vulcanizate obtained are unfavorable.

In the present invention, the sticking property can be further improved by using other phosphorus-containing compound together with the phosphoric acid ester plasticizer. Examples of phosphorus-containing compounds include phosphoric acid ester compounds, phosphorous acid ester compounds, ether type phosphoric acid ester compounds, and specific examples thereof include tris (nonylphenyl) phosphite, 4,4′- Examples include isopropylidene diphenol alkyl phosphite, triallyl phosphate, and dimethyl methyl phosphonate. The addition amount is 100 parts by weight of the elastomer,
It is 1 to 50 parts by weight, preferably 1 to 20 parts by weight.

In the present invention, other compounding agents can be used in combination as long as the effect is not impaired. As an example,
Guanidine-based, thiazole-based, thiuram-based vulcanization accelerators, zinc white, stearic acid, carbon black, silica, talc, calcium carbonate and other reinforcing agents, fillers, process oils, processing aids, and anti-aging agents Are usually used. The vulcanizable rubber composition of the present invention is produced by using the above-mentioned copolymer, plasticizer, vulcanizing agent, vulcanization accelerator, and other compounding ingredients in a commonly used mixer such as a roll or Banbury.

[0015]

The vulcanizate obtained by vulcanizing the rubber composition of the present invention is excellent in oil resistance, cold resistance, heat resistance and the like, and is particularly applicable to a wide range of applications because it does not cause a sticking phenomenon on a metal surface. it can. Main applications are O-ring, packing,
Rubber products for various seals such as gaskets; fuel hoses for automobiles, oil cooler hoses, hoses such as power steering hoses, etc., but can be applied to all rubber parts used in contact with metal.

[0016]

EXAMPLES Hereinafter, the composition of the present invention will be specifically described with reference to Examples. In the examples, the physical properties are JIS K63.
It measured according to 01. The sticking test method is as follows. Adhesion test method 1. Vulcanized rubber (30 mm x 50 mm x 2 mm) and iron plate (SAE1020, 30 mm x 60 mm x 2.5 mm)
Are superposed on each other, and the vulcanized rubber portion is compressed by 20% by using a compression device of JISK6301 compression set test. 2. (Method A) The laminated body of the vulcanized rubber and the iron plate is immersed in Nisseki Motor Oil PAN-XX in a compressed state,
Treat at 150 ° C. for 70 hours. (Method B) The laminated body of the vulcanized rubber and the iron plate in a compressed state in a gear oven at 150 ° C. for 70 hours or 15
Process at 0 ° C. for 168 hours. 3. The laminate was taken out and measured according to the 90 ° peeling test of JIS K6301. 4. The results were expressed by the average peeling load and the rubber adhesion area (%).

(Experiment Nos. 1 to 9) Hydrogenated unsaturated nitrile-unsaturated carboxylic acid ester-conjugated diene copolymer, acrylonitrile / butyl acrylate / butadiene / hydrogenated butadiene = 20/35/5/40 (weight ratio) ) Was used. This polymer is shown in Table 1.
According to each compounding recipe (unit is parts by weight), kneading was carried out with a roll to prepare rubber compounds having different kinds of phosphate ester plasticizers. This was heated under pressure at 160 ° C. for 20 minutes to obtain a sheet-shaped vulcanized product having a thickness of 2 mm, and each physical property was measured. The results and the results of the sticking test are shown in Table 2.

[0018]

[Table 1]

* 1 Hercules α, α-bis (tertiary butylperoxy-m-isopropyl) benzene * 2 Shiraishi Calcium Substituted diphenylamine * 3 Ouchi Shinko 2-mercaptobenzimidazole zinc salt * 4 Di-n -Octyl phthalate * 5 Di-n-octyl adipate * 6 Ether-thioether plasticizer * 7 Tri- (2-ethylhexyl) phosphate * 8 Tricresyl phosphate * 9 Triphenyl phosphate * 10 Toho Chemical Co., Ltd. ether type phosphoric acid Amide * 11 4,4'-isopropylidene diphenol alkyl phosphate manufactured by Asahi Denka Co., Ltd.

[0020]

[Table 2]

As can be seen from Table 2, by adding the phosphoric acid ester plasticizer, the average peeling load between the hydrogenated unsaturated nitrile-unsaturated carboxylic acid ester-conjugated diene copolymer and the metal plate (iron plate), that is, peeling The strength is low, and the amount of rubber attached to the metal surface is significantly reduced.

(Experiment Nos. 10 to 18) Three kinds of acrylic rubbers were used as polymers, and kneaded with a roll according to the compounding recipe of Table 3 to prepare rubber compounding. These 1
After heating in a press at 70 ° C for 20 minutes, add another 15
Each physical property was measured by heating at 0 ° C. for 4 hours to obtain a sheet-shaped vulcanized product having a thickness of 2 mm. The results and the results of the sticking test are shown in Table 4.

[0023]

[Table 3]

* 12 Active chlorine group-containing acrylic rubber, manufactured by Toa Paint Co., Ltd. * 13 Active chlorine group-containing acrylic rubber, manufactured by Nippon Oil Seal Co., Ltd. * 14 Active chlorine group-containing acrylic rubber, manufactured by Nippon Zeon Co., Ltd. * 15 Fatty acid ester-based processing aid Agent, manufactured by Dainippon Ink and Chemicals, Inc. * 16 Zinc di-n-butyldithiocarbamate, manufactured by Ouchi Shinko Co., Ltd. * 17 2,4,6-Trimercapto-s-triazine, manufactured by Nippon Zeon Co., Ltd. * 18 N- (cyclohexylthio) Phthalimide, manufactured by Mitsubishi Monsanto Chemical Co., Ltd. * 19 Diethyl thiourea, manufactured by Ouchi Shinko Co., Ltd.

[0025]

[Table 4]

As can be seen from Table 4, the addition of the phosphoric acid ester type plasticizer and other phosphorus-containing compounds also significantly reduced the peel strength of the acrylic rubber as compared with Experiment No. 18 in which the acrylic rubber was not added, and the metal surface The amount of rubber adhering to the rubber is significantly reduced.

Claims (4)

[Claims] 1. A rubber composition comprising 100 parts by weight of an elastomer containing an unsaturated carboxylic acid ester as a polymerization component and 1 to 50 parts by weight of a phosphoric acid ester plasticizer. 2. 100 parts by weight of an elastomer containing an unsaturated carboxylic acid ester as a polymerization component is blended with 1 to 50 parts by weight of a phosphoric acid ester plasticizer and 1 to 50 parts by weight of a phosphorus-containing compound other than the above. A rubber composition comprising: 3. A vulcanizable rubber composition comprising the rubber composition according to claim 1 and a vulcanizing agent. 4. A rubber member obtained by molding and heating the vulcanizable rubber composition according to claim 3.