JP3348471B2 - Rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copolymer rubber composition containing a specific monomer component having excellent heat resistance, oil resistance and cold resistance suitable for use as industrial materials. More specifically, the present invention relates to a copolymer rubber composition having an ester bond in a polymer main chain.

[0002]

2. Description of the Related Art Conventionally, natural rubber, styrene-butadiene rubber copolymer rubber (SBR), polybutadiene rubber (BR), polyisoprene rubber (IR), butyl rubber (IIR) have been used as industrial materials mainly for automobile parts. , Acrylonitrile-butadiene copolymer rubber (NBR), chloroprene rubber (CR), ethylene-propylene-diene terpolymer rubber (EPDM), and acrylic rubber (A
CM) and the like are known. However, in recent years,
There is a growing demand for rubber of such industrial materials to have advanced functions that cannot be satisfied with conventional levels of heat resistance, cold resistance and oil resistance.

[0003] In order to improve the physical properties of these rubbers, a change in the polymer composition and a change in the type and amount of the compounding agent are mainly carried out. However, even with these changes, it is difficult to improve all of the heat resistance, cold resistance, and oil resistance. For example, in acrylonitrile-butadiene copolymer rubber, oil resistance and heat resistance can be improved by increasing the content of acrylonitrile,
Cold resistance deteriorates. Therefore, as a means for improving the heat resistance, cold resistance and oil resistance of the acrylonitrile-butadiene copolymer rubber, attempts have been made to introduce an unsaturated carboxylic acid ester. However, in this method,
Although heat resistance is improved, cold resistance and oil resistance deteriorate. For acrylic rubber, a method of improving cold resistance by introducing 2-methoxyethyl acrylate as a main component monomer is known [Journal of the Rubber Society of Japan, 53 (6) P3
67 (1980)]. However, this method improves oil resistance, but deteriorates heat resistance.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has been developed in view of the above problem. An object is to provide a rubber composition using the coalescence.

[0005]

Means for Solving the Problems (A) The following structural formula (I)
A monomer composed of a cyclic ketene acetal represented by the formula:
9.9% by weight, (B) 0.1 to 10% by weight of a crosslinkable monomer, and (C) 0 to 94 of an acrylic unsaturated monomer copolymerizable with the components (A) and (B). Mooney viscosity (ML _{1 + 4} , 100 ° C.) having a polymerization composition of 9.9% by weight is 15
To 150 parts by weight of a copolymer rubber,
It is intended to provide a rubber composition comprising 10 parts by weight.

[0006]

Embedded image

First, the cyclic ketene acetal which is the component (A) used in the present invention is represented by the above structural formula (I),
In the formula, n is an integer of 2 to 5, and the case of n = 4 is preferable because the ring opening ratio is as high as almost 100% and the cold resistance is excellent. In the present invention, an ester bond can be incorporated into the polymer main chain by combining and copolymerizing one or more of the above-described cyclic ketene acetals with other monomers.

[0008] Component (B) is 0.1 to 10% by weight, preferably 0.1 to 5% by weight, and if it is less than 0.1% by weight, the resulting copolymer rubber has poor tensile strength. %
If it exceeds, elongation decreases.

As the crosslinkable monomer of the component (B), the following compounds can be exemplified. Diene monomer Unsaturated group-containing unsaturated carboxylic acid ester Epoxy group-containing vinyl monomer Carboxyl group-containing vinyl monomer Reactive halogen atom-containing vinyl monomer Hydroxyl group-containing vinyl monomer Amide group-containing vinyl monomer Here, as the diene monomer, for example, butadiene, ethylidene norbornene, isoprene, piperidine, divinylbenzene, vinylcyclohexene, chloroprene, methylbutadiene, cyclopentadiene, methylpentadiene, dimethylvinylstyrylsilane, etc. Examples of the unsaturated carboxylic acid ester include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, and dihydrodicyclopentacidienyloxyethyl (meth).
Acrylate, (meth) vinyl acrylate, dimethyl vinyl methacryloxymethyl silane, etc., as the epoxy group-containing vinyl monomer, for example, glycidyl (meth) acrylate, allyl glycidyl ether, etc.
As the carboxyl group-containing vinyl monomer, for example,
(Meth) acrylic acid, itaconic acid, fumaric acid mono-n-
Butyl, monoethyl maleate, mono-n-maleate
Butyl esters, 2-methacryloyloxyethylhexahydrophthalic acid, 2-methacryloyloxyethylmaleic acid and the like are examples of reactive halogen atom-containing vinyl monomers, for example, 2-chloroethyl vinyl ether, vinyl chloroacetate, allyl chloroacetate , Chloromethylstyrene and the like, as the hydroxyl group-containing vinyl monomer, for example, 2-hydroxyethyl acrylate, 2
-Hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, N-methylol (meth) acrylamide and the like, as an amide group-containing vinyl monomer,
For example, acrylamide, methacrylamide and the like can be mentioned.

The acrylic unsaturated monomer of component (C) includes methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, and (meth) acrylate. ) Hexyl acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, dimethyl itaconate, diethyl amalate, dimaleate unsaturated carboxylic acid esters such as n-butyl, styrene, vinyltoluene, α-methylstyrene, vinylnaphthalene, acrylonitrile, vinyl acetate, vinylidene chloride, vinyl chloride,
Isobutylene, ethylene, and propylene. The above copolymerizable monomers can be used alone or in combination of two or more.

The copolymer rubber comprising the cyclic ketene acetal of the present invention can be easily produced by suspension polymerization, bulk polymerization, emulsion polymerization or solution polymerization in the presence of a radical polymerization initiator. As an emulsifier for producing a copolymer rubber by an emulsion polymerization method, for example, alkyl sulfate, alkyl aryl sulfonate, higher fatty acid salt and the like can be mentioned.

The polymerization reaction can be carried out at a temperature of 0 to + 150 ° C. As the radical polymerization initiator for initiating polymerization, for example, azo compounds represented by azobisisobutyronitrile, benzoyl peroxide, conventionally known organic peroxides such as paramenthane hydroperoxide, potassium persulfate , An inorganic sulphate such as ammonium persulfate, and a redox catalyst represented by a combination of an organic peroxide and iron sulfate. These radical initiators are usually used in an amount of 0.01 to 3% by weight based on the monomer mixture. Further, a molecular regulator can be used if necessary, and specific examples thereof include mercaptans such as t-dodecyl mercaptan, octyl mercaptan, n-tetradecyl mercaptan, dimethyl xanthogen disulfide, ethylene bromide, and carbon tetrachloride. And the like.

In the polymerization reaction, after reaching a predetermined polymerization conversion, a reaction terminator such as N, N-diethylhydroxyamine is added to stop the polymerization reaction, and then the unreacted monomer in the obtained latex is added. The body is removed by steam distillation, an antioxidant such as phenols or amines is added, and the mixture is mixed with a metal aqueous solution such as an aqueous solution of ammonium sulfate or calcium chloride to coagulate the latex, followed by drying and copolymerization. Rubber can be obtained. When producing a copolymer rubber by suspension radical polymerization, polyvinyl alcohol or the like is added as a dispersant,
Polymerization is carried out using an oil-soluble radical initiator such as azobisisobutyronitrile and benzoyl peroxide, and after the polymerization is completed, water is removed to obtain a copolymer rubber. Further, also in the case of producing a copolymer rubber by solution radical polymerization, generally known methods can be employed.

The molecular weight of the copolymer rubber of the present invention thus obtained is determined by the type and amount of the molecular weight regulator, the type and amount of the radical initiator, the polymerization temperature, the type and amount of the solvent, and the monomer concentration. It can be prepared by changing the reaction conditions such as The Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the obtained copolymer rubber is 15 to 150,
Preferably it is 20-100. If the Mooney viscosity of the obtained copolymer rubber is less than 15, the mechanical strength of the copolymer rubber is inferior. On the other hand, if it exceeds 150, the processability deteriorates, which is not preferable. The glass transition temperature of the copolymer rubber is preferably-
20 ° C. or less.

When the crosslinkable monomer is a diene monomer and / or an unsaturated group-containing carboxylic acid ester, the crosslinking agent for the copolymer rubber of the present invention is sulfur or an organic sulfur compound. And an organic peroxide.
When an epoxy group-containing vinyl monomer is used as the crosslinkable monomer, a polyamine, a polycarboxylic acid,
Acid anhydrides, polyamides, sulfonamides, dithiocarbamates, ammonium organic carboxylate and the like are used as crosslinking agents. Furthermore, when a carbonyl group-containing vinyl monomer is used as the crosslinkable monomer, a polyamine, a polyepoxide, a polyol, or the like is used as a crosslinker. Further, when a reactive halogen atom-containing vinyl monomer is used as the crosslinkable monomer, a metal soap, an organic carboxylic acid ammonium salt, a polyamine, a polycarbamate, trithiocyanuric acid, or the like is used as a crosslinker. Further, when a hydroxyl group-containing vinyl monomer is used as the crosslinkable monomer, a polyisocyanate, a polycarboxylic acid, an alkoxymethylmelamine or the like is used as a crosslinker. Further, when an amide group-containing vinyl monomer is used as the crosslinkable monomer, aminoformaldehyde is used as a crosslinker.

Among these crosslinking agents, sulfur includes:
Any of powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur and highly dispersible sulfur can be used. The organic sulfur compound is a compound that releases active sulfur by thermal dissociation, and examples thereof include thiuram-based accelerators such as tetramethylthiuram disulfide and 4,4-dithiomorpholine.

Examples of the organic peroxide include 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne,
5-dimethyl-2,5-di (t-butylperoxy) hexane, 1,3-bis (t-butylperoxyisopropyl) benzene, dicumyl peroxide, dibutyl peroxide, 1,1-di-t- Butyl peroxy-3,
3,5-trimethylcyclohexane, t-butylcumyl peroxide, t-butylperoxy-isopropyl carbonate and the like are used.

Examples of the modified alkylphenol resin include an alkylphenol formaldehyde resin and a brominated alkylphenol formaldehyde resin. Examples of the polyisocyanate include hexamethylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and the like. Examples of the polyamine include triethylenetetramine, methylenedianiline, diethylenetriamine, and the like. Examples of the metal soap include sodium stearate and potassium stearate. Examples of the organic carboxylic acid ammonium salt include ammonium benzoate and ammonium adipate. Examples of the polycarboxylic acid include adipic acid and octadecyldicarboxylic acid. Examples of the acid anhydride include pyromellitic anhydride,
Maleic anhydride, dodecenyl succinic anhydride and the like can be mentioned. Examples of dithiocarbamic acid include hexamethylenediaminecarbamate, zinc dimethyldithiocarbamate, and the like. As polyepoxide,
For example, ethylene glycol diglycidyl ether,
Examples thereof include 1,6-hexanediol diglycidyl ether. Examples of the polyol include 1,4-butanediol, 1,1,1-trimethylolpropane, and the like.

The amount of the crosslinking agent in the rubber composition of the present invention is usually 0.1 to 10 parts by weight based on 100 parts by weight of the copolymer rubber containing cyclic ketene acetal as a main component. If the amount is less than 0.1 part by weight, the crosslinking hardly proceeds, while if it exceeds 10 parts by weight, the crosslinking density becomes too large, and the physical properties of the obtained rubber composition are impaired.

In order to shorten the crosslinking time, lower the crosslinking temperature, and improve the performance of the crosslinked product, these crosslinking agents include:
A crosslinking aid can be added. For example, when sulfur is used as a crosslinking agent, thiazoles such as mercaptobenzothiazole, thiurams such as tetramethylthiuram disulfide, guanidines such as diphenylguanidine, and dithiocarbamates such as zinc dimethyldithiocarbamate help in crosslinking. It can be used effectively as an agent.

When an organic peroxide is used as a crosslinking agent, ethylene glycol dimethacrylate,
1,3-butanediol dimethacrylate, 1,4-
Butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 2,2'-bis (4-methacryloyldiethoxyphenyl) propane, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, divinyl Benzene, N, N'-methylenebisacrylamide, p-quinonedioxime, p, p'-
Dibenzoylquinone dioxime, triazinedithiol, triallyl isocyanurate, bismaleimide, silicone oil with a high vinyl content, and the like can be effectively used as a crosslinking agent.

When metal soap is used as a crosslinking agent, for example, sulfur and dipentamethylenethiuram tetrasulfide can be effectively used as the crosslinking agent. When an amine is used as a crosslinking agent, for example, diphenylguanidine and diorthotolylguanidine can be effectively used as a crosslinking aid.

The rubber composition of the present invention is prepared by adding each of the above-mentioned components and, if necessary, various compounding agents, and mixing using a conventional mixer such as a two-roll mixer or a Banbury mixer. Is done. Among the compounding agents, examples of the filler include white fillers such as silica, calcium carbonate, talc, and magnesium carbonate in addition to carbon black.

Among the compounding agents, dispersants include, for example, higher fatty acids and metal salts or amide salts thereof; plasticizers include, for example, phthalic acid derivatives, adipic acid derivatives, polyether esters; For example, lubricating oils, process oils and castor oils; examples of antioxidants include amines such as 4,4 '-(α, α'-dimethylbenzyl) diphenylamine and 2,2'-methylenebis (4-methyl -6-t-butylphenol)
Phenols, imidazoles, etc .; other crosslinking accelerators, pigments, flame retardants, scorch inhibitors, tackifiers, lubricants, etc. can be arbitrarily compounded.

The thus obtained rubber composition of the present invention can be molded and cross-linked under ordinary cross-linked rubber production conditions to form a cross-linked product. That is, after molding, usually at 150 to 180 ° C. for 10 to 60 minutes, 50 to 1
Primary cross-linking under heating and pressure of 50 kg / cm ² and, if necessary, secondary cross-linking at 150 to 180 ° C. for 1 to 20 hours to give a crosslinked product having excellent heat resistance, cold resistance and oil resistance. it can.

[0026]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist. In the examples,
Parts and percentages are by weight unless otherwise specified. First, the synthesis of the monomer (A) will be described.

Synthesis Example 1 625 g of chloroacetaldehyde dimethyl acetal
(5.0 mol) and 450 g of 1,4-butanediol
(5.0 mol) in a mixture of ion-exchange resin Dowex 50
6.25 g of (Na ⁺ ) [manufactured by DuPont] was added, and the mixture was refluxed at 115 ° C. in a 31 flask. The reaction was stopped when 10 moles of methanol had distilled off, and Dowex 50 was removed by filtration. The reaction solution was distilled to obtain 2-chloromethyl-1,3-dioxepane. In a 31 flask, 740 ml of t-butyl alcohol and 600 g of calcium t-butoxy (4.
(0 mol) at 80 to 90 ° C., 448 g (4.0 mol) of 2-chloromethyl-1,3-dioxepane are added dropwise. After completion of the dropwise addition, the temperature in the flask is raised to 100 ° C. and refluxed for 5 hours. Thereafter, the reaction was stopped, 21 diethyl ether was added, and KCl was removed by filtration. Further distillation yielded 2-methylene-1,3-dioxeban.

Synthesis Example 2 In a separable flask sufficiently substituted with nitrogen gas, as a dispersing agent, polyvinyl alcohol 0.5 having a hydrolysis rate of 80% was added.
After adding 300 parts of water and 0.1 part of azobisisobutyronitrile initiator, 2-methylene-1,3-dioxepane 98 obtained in Synthesis Example 1 as component (A) was added.
Parts, 2 parts of vinyl chloroacetate were charged as the component (B),
Polymerization was carried out at a reaction temperature of 60 ° C. until the conversion of the monomer compound reached 90%. The polymer was sufficiently washed with water and filtered to obtain a copolymer P-2. Table 1 shows the polymer composition.

Synthesis Examples 3 to 9 Polymerization was carried out in the same manner as in Synthesis Example 2, and copolymers P-3 to P-
9 was obtained. Table 1 shows the polymer composition. The polymer composition was calculated from the chemical shift of the ¹³ C-NMR spectrum. However, the vinyl chloroacetate content was determined by a fluorescent X-ray method. Glass transition temperature was measured with a differential scanning calorimeter.

[0030]

[Table 1]

Examples 1 to 5 Using the copolymers P-2 to P-6 obtained as described above, according to the compounding ratios shown in Tables 2 and 3, each component was mixed in a conventional manner using an internal mixer. And kneaded and blended to produce respective rubber compositions. As the reinforcing filler of the component (b), MAF Carbon Black Seast 116 (trade name, manufactured by Tokai Carbon Co., Ltd.) is used. As the component (c), the antioxidant Nocrack CD [trade name, Ouchi Shinko Chemical Co., Ltd.] Co., Ltd.], sodium stearate, potassium stearate, and sulfur were used in the formulations shown in Tables 2 and 3, respectively. Normal physical properties of each rubber composition thus prepared,
Oil resistance and cold resistance were evaluated according to the following. Table 2 shows the results.

[0032]

[Table 2]

[0033]

[Table 3]

Normal physical properties, oil resistance, and cold resistance are determined according to JIS K
6301 and evaluated according to the following conditions. Normal physical properties: press vulcanization at 170 ° C. × 20 minutes, oven vulcanization at 175 ° C. × 4 hours Heat resistance test: 175 ° C. × 500 hours, oven oven Oil resistance: 150 ° C. × 70 using JIS # 3 oil
Time immersion Cold resistance: Low-temperature impact embrittlement test P synthesized in Comparative Examples 1 to 3 and Synthesis Examples 7 to 9 in the table
It is the result of having evaluated physical properties similarly to the said Example using -7 to P-9. As is clear from the results of Tables 2 and 3, the rubber-like elastic body obtained by crosslinking (vulcanizing) the rubber composition of the present invention has excellent cold resistance and oil resistance.

[0035]

The rubber-like elastic material obtained by crosslinking (vulcanizing) the rubber composition according to the present invention has a better balance between oil resistance and cold resistance than existing polymers by introducing an ester bond into the main chain. Is obtained, which is considered to be industrially useful.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI C08L 37/00 C08L 37/00 (72) Inventor Tsuyoshi Endo 54-13 Miyagaya, Nishi-ku, Yokohama-shi (56) References JP Akira 60-31506 (JP, A) U.S. Pat. No. 5,294,688 (US, A) F. etc. , Synthesis of bioabs available networks from methacrylate-encapsulated polyesters. , Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.), 1992, 33/2, p. 459-460 (58) Fields investigated (Int. Cl. ⁷ , DB name) C08F 24/00 C08L 37/00 C08L 67/00-67/08 CAPLUS (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] (1) (A) 5 to 99.9% by weight of a monomer comprising a cyclic ketene acetal represented by the following structural formula (I), (B) 0.1 to 10% by weight of a crosslinkable monomer %, And (C) a Mooney viscosity (ML _{1 + 4} , 100 ° C.) having a polymerization composition of 0 to 94.9% by weight of an acrylic unsaturated monomer copolymerizable with the components (A) and (B). Is a rubber composition obtained by blending 0.1 to 10 parts by weight of a crosslinking agent with 100 parts by weight of a copolymer rubber having a particle size of 15 to 150. Embedded image (In the formula, n represents an integer of 2 to 5.)