JP3156438B2 - Acrylic copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an acrylic copolymer. More specifically, the present invention relates to an acrylic copolymer excellent in balance between cold resistance and heat resistance.

[0002]

2. Description of the Related Art Conventionally, acrylic rubber has been used for applications requiring heat resistance and oil resistance such as automobile parts.
In recent years, however, there has been a demand for advanced functions that are not satisfactory with conventional acrylic rubbers, specifically those that have improved cold resistance and heat resistance without impairing oil resistance.

[0003] With respect to the improvement of cold resistance, 2-
A method of copolymerizing methoxyethyl acrylate is known (Journal of the Rubber Society of Japan, Vol. 53, No. 6, page 367, 1980).
Year), although this method improves cold and oil resistance,
The result is that the heat resistance deteriorates. Also, a method of improving heat resistance by copolymerizing a methacrylic acid ester is known, but in this case, cold resistance is deteriorated.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an acrylic copolymer which gives a vulcanized rubber satisfying cold resistance and heat resistance without impairing conventional oil resistance.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
(A) at least one of alkyl (meth) acrylate and alkoxyalkyl (meth) acrylate 95 to 50 mol
% , (B) 2-45 mol% of saturated fatty acid allyl ester, (c) 0.1-10 mol% of crosslinkable monomer and (d) copolymer of 30-0 mol% of a monomer copolymerizable therewith And is achieved by an acrylic copolymer having a viscosity average molecular weight of 100,000 to 5,000,000.

The alkyl (meth) acrylate of the component (a) includes, for example, methyl acrylate, ethyl acrylate, n- or iso-propyl acrylate, n- or iso-butyl acrylate, n-amyl acrylate, n-hexyl acrylate, -Ethylhexyl acrylate,
n-octyl acrylate, an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms (including those having a substituent such as a cyano group) such as 2-cyanoethyl acrylate or a corresponding alkyl methacrylate is used, and preferably ethyl acrylate Alternatively, n-butyl acrylate or methyl methacrylate, ethyl methacrylate or n-butyl methacrylate is used.

The alkoxyalkyl (meth) acrylates include, for example, those having 2 to 2 carbon atoms such as methoxymethyl acrylate, ethoxymethyl acrylate, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-butoxyethyl acrylate or the corresponding methacrylate. An alkoxyalkyl (meth) acrylate having an alkoxyalkyl group of 8 is used, preferably 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate or the corresponding methacrylate.

The component (a) is used as a main component of the acrylic copolymer at a ratio of about 95 to 50 mol%, preferably about 90 to 60 mol%, and comprises an alkyl (meth) acrylate and an alkoxyalkyl ( When both (meth) acrylates are used, the former is about 90 to 10 mol%, and the latter is about 10 to 10 mol%.
It is generally used in a proportion of ~ 90 mol%.

A portion of the component (a), specifically, up to about 30 mol%, may be substituted with another copolymerizable monomer and copolymerized. Examples of such a copolymerizable monomer include ethylene, propylene, vinyl chloride, vinylidene chloride, acrylonitrile, styrene, vinyl acetate, ethyl vinyl ether, butyl vinyl ether, alkyl methacrylate, and alkoxyalkyl methacrylate.

The saturated fatty acid allyl ester of the component (b) includes allyl acetate, allyl propionate, allyl n-valerate, allyl n-nonanoate and the like. Preferably, the copolymerization is carried out at a ratio occupying 5 to 30 mol%. If the copolymerization ratio is lower than this, the heat resistance is reduced, while if the copolymerization is performed at a higher ratio, the cold resistance and the hydrolysis resistance are reduced.

As the component (c) forming the crosslinking point of the copolymer and the type of the reactive group thereof, the following crosslinking agents can be used. (A) Epoxy group-containing vinyl monomer Allyl glycidyl ether, glycidyl vinyl ether, glycidyl acrylate, glycidyl methacrylate and the like are exemplified.Examples of these crosslinking agents include, for example, ammonium carboxylate, polyamine, polyamine salt, dithiocarbamate And a combination of a polycarboxyl compound and a quaternary ammonium salt or a quaternary phosphonium salt, a combination of an imidazole derivative and an alkyl sulfate or an alkyl sulfonate, and a combination of a polyamine or guanidine derivative and a sulfur or sulfur donating compound. (B) carboxyl group-containing vinyl monomer acrylic acid, methacrylic acid, itaconic acid, maleic acid monoester and the like are exemplified, and as these crosslinking agents,
For example, a polyamine, a polyamine salt, a metal oxide, a combination of a polyepoxy compound and a quaternary ammonium salt, a quaternary phosphonium salt or a basic compound, and a combination of a polyamine or a polyamine salt and a guanidine derivative are exemplified. (C) Reactive halogen-containing vinyl monomer 2-chloroethyl vinyl ether, 2-chloroethyl acrylate, monochlorovinyl acetate and the like are exemplified, and as these crosslinking agents, for example, polyamine, polyamine salt,
Examples thereof include a combination of a fatty acid alkali metal salt and a sulfur or sulfur donor compound, trithiocyanuric acid and a fatty acid metal salt, dicyandiamide, a metal oxide, a dithiocarbamate or a thiuram compound. (D) Diene monomer isoprene, pentadiene, vinylcyclohexene, chloroprene, butadiene, methylbutadiene, cyclopentadiene, methylpentadiene, ethylidene norbornene, vinylidene norbornene, allyl acrylate,
Examples thereof include 2-butenyl acrylate, dihydroethylidene norbornenyl acrylate, dihydrodicyclopentadienyl acrylate, and the like.Examples of these crosslinking agents include sulfur, or benzoyl peroxide, dicumyl peroxide, 2,5-dimethyl -2,5-di (No.
(3 butyl peroxy) hexane, organic peroxide such as 1,3-bis (tertiary butyl peroxyisopropyl) benzene and tri (meth) allyl cyanurate, tri (meth) allyl isocyanurate, 1,2-polybutadiene, ethylene glycol
Examples thereof include a combination with a polyfunctional unsaturated compound such as (meth) acrylate. Instead of using these crosslinking agents, crosslinking may be performed only by heating. (E) Hydroxyl group-containing vinyl monomer hydroxyalkyl acrylate, hydroxyalkyl methacrylate, hydroxyalkoxy acrylate, N-methylol acrylamide and the like are exemplified.Examples of these crosslinking agents include polyisocyanates such as hexamethylene diisocyanate and tolylene diisocyanate And polycarboxylic acids such as adipic acid, alkoxymethylmelamines such as methoxymethylmelamine, methylated urea, butylated urea and the like. (F) Trialkoxysilyl group-containing vinyl monomer Vinyltrimethoxysilane, allyltrimethoxysilane, 3- (trimethoxysilyl) -propyl (meth) acrylate and the like are exemplified, and these are usually self-crosslinked.

These crosslinking point-forming (c) components can be copolymerized by using two or more kinds in combination. For example, when an epoxy group-containing vinyl monomer and a carboxyl group-containing vinyl monomer are used in combination. In such a case, a quaternary ammonium salt, a quaternary phosphonium salt, a guanidine derivative, an imidazole derivative, or the like is used as the crosslinking agent, and a carboxyl group-containing vinyl monomer and a reactive halogen-containing vinyl monomer are used. When used in combination, alkali metal salts of organic carboxylic acids are used alone or in combination with quaternary ammonium salts, quaternary phosphonium salts, guanidine derivatives and the like as crosslinking agents.

The component (c) is used in an amount of at least 0.1 mol% from the viewpoint of introducing a crosslinkable group. However, if it is used in an amount exceeding 10 mol%, the heat resistance of the crosslinked cured product will be impaired.

The copolymerization reaction is carried out in the presence of a radical polymerization initiator by an emulsion polymerization method, a suspension polymerization method, a solution polymerization method, a bulk polymerization method, or the like. As the radical polymerization initiator, generally used organic peroxides, azo compounds,
Inorganic persulfates and the like are preferably used as a redox system, and a chain transfer agent such as an organic mercapto compound and an organic sulfide compound is also used.

The obtained copolymer has a viscosity average molecular weight of about 100,000 to 5,000,000, preferably about 300,000 to 3,000,000 (estimated from the intrinsic viscosity of polyethyl acrylate).

A vulcanizing agent, a vulcanization accelerator, an antioxidant, a softening agent, a dispersing agent, a lubricant and the like are added to the obtained acrylic copolymer, if necessary. About 15
Performed by primary vulcanization at 0-210 ° C for about 0.5-15 minutes,
If necessary, the secondary vulcanization is carried out at about 120 to 180 ° C. for about 1 to 20 hours.

[0017]

EFFECTS OF THE INVENTION By copolymerizing a saturated fatty acid allyl ester in an acrylic copolymer, the acrylic copolymer has a well-balanced acrylic copolymer which is satisfactory in both cold resistance and heat resistance without impairing oil resistance. A polymer is obtained.

Therefore, the acrylic copolymer is effectively used as a molding material for sealing materials, O-rings and the like.

[0019]

Next, the present invention will be described by way of examples. Parts are parts by weight.

Example 1 Monomer mixture 100 parts Ethyl acrylate 25 mol% n-butyl acrylate 30 mol% 2-methoxyethyl acrylate 30 mol% n-allyl valerate 13 mol% Vinyl chloroacetate 2 mol% Sodium lauryl sulfate 10 Part Lauryl mercaptan 0.1 part Ammonium persulfate 0.0125 part Sodium bisulfite 0.0125 part Water 200 parts or more An aqueous calcium solution was added for coagulation, and the coagulated product was sufficiently washed with water to obtain a copolymer having a viscosity average molecular weight of 680,000.

100 parts of the obtained copolymer, 60 parts of HAF carbon black, 1 part of stearic acid, sodium stearate
A mixture of 2.5 parts, 0.5 part of potassium stearate and 0.3 part of sulfur was kneaded with a 10-inch roll, and subjected to primary vulcanization (press vulcanization) at 180 ° C. for 6 minutes and a second oven in a oven at 150 ° C. for 15 hours. Next vulcanization was performed to obtain a vulcanized rubber sheet having a thickness of 2 mm. For this vulcanized rubber sheet, in accordance with JIS K-6301, tensile test, heat resistance test (hardness change after air heating aging of 175 ° C., 168 hours), cold resistance test (glass transition temperature by DSC method) and Oil resistance test (150 ° C, 7 in JIS No.3 oil)
Volume change after immersion for 0 hours).

Example 2 In the copolymerization reaction of Example 1, the following was used as a monomer mixture to obtain a copolymer having a viscosity average molecular weight of 1.6 million. Ethyl acrylate 20 mol% n-butyl acrylate 30 mol% 2-methoxyethyl acrylate 30 mol% n-allyl valerate 18 mol% Allyl glycidyl ether 2 mol%

The kneading, vulcanization and various tests were carried out in the same manner as in Example 1 for a blend of 100 parts of the obtained copolymer, 60 parts of HAF carbon black, 1 part of stearic acid and 2 parts of ammonium benzoate. .

Example 3 In the copolymerization reaction of Example 1, the following was used as a monomer mixture to obtain a copolymer having a viscosity average molecular weight of 1.2 million. 35 mol% n-butyl acrylate 40 mol% 2-methoxyethyl acrylate 23 mol% n-allyl valerate 2 mol% vinyl chloroacetate 2 mol%

With respect to the obtained copolymer, preparation, kneading, vulcanization and various tests were carried out in the same manner as in Example 1.

Example 4 In the copolymerization reaction of Example 1, the following was used as a monomer mixture to obtain a copolymer having a viscosity average molecular weight of 750,000. Ethyl acrylate 25 mol% n-butyl acrylate 30 mol% 2-methoxyethyl acrylate 30 mol% Allyl propionate 13 mol% Vinyl chloroacetate 2 mol%

With respect to the obtained copolymer, preparation, kneading, vulcanization and various tests were carried out in the same manner as in Example 1.

Comparative Example 1 In the copolymerization reaction of Example 1, the following was used as a monomer mixture to obtain a copolymer having a viscosity average molecular weight of 1,080,000. n-butyl acrylate 46 mol% 2-methoxyethyl acrylate 52 mol% vinyl chloroacetate 2 mol%

With respect to the obtained copolymer, preparation, kneading, vulcanization and various tests were carried out in the same manner as in Example 1.

Comparative Example 2 In the copolymerization reaction of Example 1, the following was used as a monomer mixture to obtain a copolymer having a viscosity average molecular weight of 1,250,000. Ethyl acrylate 26 mol% n-butyl acrylate 36 mol% 2-methoxyethyl acrylate 36 mol% Allyl glycidyl ether 2 mol%

With respect to the obtained copolymer, preparation, kneading, vulcanization and various tests were carried out in the same manner as in Example 2.

Test results in each of the above Examples and Comparative Examples
Are shown in the following table. table Example Comparative example  Measurement item 1 2 3 4 1 2 Tensile strength (kgf / cm^Two) 145 142 130 148 125 140 Elongation (%) 340 330 320 325 325 330 Heat resistance (ΔHs) +5 +6 +6 +4 +10 +14 Cold resistance (℃) -36 -38 -42 -34 -43 -34 Oil resistance (ΔV) 24.4 28.0 35.2 24.2 38.5 28.0

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08F 220/18 C08F 218/02-218/10 CA (STN)

Claims (1)

(57) [Claims] (1) 95 to 50 mol% of at least one of alkyl (meth) acrylate and alkoxyalkyl (meth) acrylate, (b) 2-45 mol% of saturated fatty acid allyl ester, (c) crosslinkable monomer An acrylic copolymer comprising a copolymer of 0.1 to 10 mol% and (d) 30 to 0 mol% of a monomer copolymerizable therewith, and having a viscosity average molecular weight of 100,000 to 5,000,000.