Acrylic rubber, process for its production, and rubber compositions, oil-and weather-resistant rubber compositions, and oil-and weather -resistant rubbers, containing the same
The objective of the present invention is to provide an acrylic ester-based copolymer rubber which gives a rubber product excellent in fuel oil resistance and tensile strength and which is crosslinkable with sulfur and/or an organic peroxide and to provide a process for producing the same, as well as a rubber composition, an oil-resistant and weather-resistant rubber composition, and an oil-resistant and weather-resistant rubber product. The acrylic ester-based copolymer rubber of the present invention comprises a structural unit derived from at least one monomer selected from the group consisting of an acrylic acid alkyl ester and an acrylic acid alkoxyalkyl ester in an amount from 40 to 91.9% by mass, a structural unit derived from an unsaturated nitrile monomer in an amount from 8 to 40% by mass, and a structural unit derived from at least one monomer selected from the group consisting of a non-conjugated cyclic polyene and a compound having a specific structure in an amount from 0.1 to 20% by mass (provided 100% by mass of total of these), and has a Mooney viscosity [ML 1+4 (100° C.)] in the range from 10 to 200.
1. An oil-resistant and weather-resistant rubber composition comprising (X) an acrylic ester-based copolymer rubber in an amount from 10 to 50% by mass and (Y) an α, β-unsaturated nitrile conjugated diene copolymer in an amount from 90 to 50% by mass (provided (X)+(Y)=100% by mass),
wherein said acrylic ester-based copolymer rubber is comprised of:
(A) a structural unit derived from at least one monomer selected from the group consisting of an acrylic acid alkyl ester and an acrylic acid alkoxyalkyl ester in an amount from 40 to 91.9% by mass,
(B) a structural unit derived from an unsaturated nitrile monomer in an amount from 8 to 40% by mass,
(C) a structural unit derived from at least one monomer selected from the group consisting of a non-conjugated cyclic polyene and compounds represented by the following formula (1) in an amount from 0.1 to 20% by mass (provided (A)+(B)+(C)=100% by mass), and
(D) a structural unit derived from an unsaturated monomer having an epoxy group in an amount from 0.1 to 20 parts by mass when the total of said structural units (A), (B) and (C) is defined as 100 parts by mass,
wherein the Mooney viscosity [ML 1+4 (100° C.)] is in the range from 10 to 200,
wherein X 1 represents a hydrogen atom or a methyl group, and n is an integer from 0 to 10.
2. The oil-resistant and weather-resistant rubber composition according to claim 1 , wherein a monomer forming said structural unit (A) is at least one selected from the group consisting of ethyl acrylate, n-butyl acrylate and methoxyethyl acrylate.
3. The oil-resistant and weather-resistant rubber composition according to claim 1 , wherein a content of said structural unit (B) is in the range from 10 to 35% by mass.
4. The oil-resistant and weather-resistant rubber composition according to claim 1 , wherein (C) is a structural unit derived from at least one non-conjugated cyclic polyene.
5. The oil-resistant and weather-resistant rubber composition according to claim 1 , wherein (C) is a structural unit derived from compounds represented by formula (1).
6. The oil-resistant and weather-resistant rubber composition according to claim 1 , wherein the Mooney viscosity is from 20 to 100.