Acrylic-based copolymer composition, method for preparing the same and acrylic-based rubber composition

A method of preparing an acrylic-based copolymer composition, comprising:

• preparing a first acrylic-based copolymer by polymerizing a monomer mixture consisting of a first (meth)acrylic acid alkyl ester monomer having a linear or cyclic alkyl group having 1 to 8 carbon atoms, a second (meth)acrylic acid alkyl ester monomer having a linear or cyclic alkyl group having 1 to 8 carbon atoms and the alkyl group being substituted with a hydroxyl group, and a (meth)acrylic acid alkoxy alkyl ester monomer having an alkoxy alkyl group having 1 to 8 carbon atoms, at a temperature of 5° C. to 15° C.;
• preparing a second acrylic-based copolymer by polymerizing a monomer mixture consisting of a (meth)acrylic acid alkyl ester monomer having a linear or cyclic alkyl group having 2 to 8 carbon atoms, a (meth)acrylic acid alkoxy alkyl ester monomer having an alkoxy alkyl group having 1 to 8 carbon atoms, and a crosslinkable monomer, at a temperature of 30° C. to 50° C., wherein the crosslinkable monomer is at least one selected from the group consisting of an epoxy group-containing monomer and a halogen-containing monomer, the epoxy-containing monomer is at least one selected from the group consisting of glycidyl (meth)acrylate, vinyl glycidyl ether, allyl glycidyl ether, and methacryl glycidyl ether, and the halogen-containing monomer is at least one selected from the group consisting of vinyl chloro acetate, vinyl bromo acetate, allyl chloro acetate, vinyl chloro propionate, vinyl chloro butyrate, vinyl bromo butyrate, 2-chloroethyl acrylate, 3-chloro propyl acrylate, 4-chloro butyl acrylate, 2-chloroethyl methacrylate, 2-bromo ethyl acrylate, 2-iodine ethyl acrylate, 2-chloroethyl vinyl ether, chloro methyl vinyl ether, 4-chloro-2-butenyl acrylate, vinyl benzyl chloride, 5-chloro methyl-2-norbornene, and 5-chloroacetoxy methyl-2-norbornene;
• and
• mixing the first acrylic-based copolymer and the second acrylic-based copolymer in a ratio of 4:6 to 6:4 by weight in a latex state,
• wherein in the first acrylic-based copolymer, a repeating unit derived from the first (meth)acrylic acid alkyl ester monomer is present in an amount of at least 80 parts by weight, and a combined repeating unit derived from the first (meth)acrylic acid alkyl ester monomer and the second (meth)acrylic acid alkyl ester monomer is present in an amount of 80 parts by weight to 95 parts by weight, and a repeating unit derived from the (meth)acrylic acid alkoxy alkyl ester monomer is present in an amount of 5 parts by weight to 20 parts by weight, based on 100 parts by weight of total repeating units, and
• in the second acrylic-based copolymer, a repeating unit derived from the (meth)acrylic acid alkyl ester monomer is present in an amount of 75 parts by weight to 95 parts by weight, a repeating unit derived from the (meth)acrylic acid alkoxy alkyl ester monomer is present in an amount of 4 parts by weight to 20 parts by weight, and a repeating unit derived from the crosslinkable monomer is present in an amount of 1 parts by weight to 10 parts by weight, based on 100 parts by weight of total repeating units.