An aspect of the present invention is an acrylic rubber containing an alkyl acrylate, ethylene and vinyl acetate as monomer units, wherein a content of a polyvinyl alcohol in the acrylic rubber is 0.5 to 2% by mass.

An aspect of the present invention is an acrylic rubber containing an alkyl acrylate, ethylene and vinyl acetate as monomer units, wherein a content of a polyvinyl alcohol in the acrylic rubber is 0.5 to 2% by mass.

An acrylic rubber containing: an alkyl acrylate unit; a crosslinking monomer unit; a unit of a bifunctional monomer represented by the following formula (A-1):

##STR00001##

wherein n represents 1 to 9, R.sup.1 represents a hydrogen atom or a methyl group, and R.sup.2 represents an alkanediyl group having 2 to 4 carbon atoms; and an ethylene unit, wherein the acrylic rubber has a toluene insoluble content of 4 to 40% by mass.

An acrylic rubber containing: an alkyl acrylate unit; a crosslinking monomer unit; a unit of a bifunctional monomer represented by the following formula (A-1):

##STR00001##

wherein n represents 1 to 9, R.sup.1 represents a hydrogen atom or a methyl group, and R.sup.2 represents an alkanediyl group having 2 to 4 carbon atoms; and an ethylene unit, wherein the acrylic rubber has a toluene insoluble content of 4 to 40% by mass.

The present invention addresses the problem of providing an emulsion having excellent emulsion stability and excellent coagulability (salting-out properties) in manufacturing of an acrylic rubber. The present invention provides an acrylic emulsion containing an acrylic polymer having an average particle diameter of 150-300 nm in a step for emulsion-polymerizing a monomer in manufacturing of an acrylic rubber.

The present invention addresses the problem of providing an emulsion having excellent emulsion stability and excellent coagulability (salting-out properties) in manufacturing of an acrylic rubber. The present invention provides an acrylic emulsion containing an acrylic polymer having an average particle diameter of 150-300 nm in a step for emulsion-polymerizing a monomer in manufacturing of an acrylic rubber.

An acrylic rubber contains a copolymer of a monomer mixture of: 25 to 46 wt. % of alkoxyalkyl acrylate, 23 to 37 wt. % of 2-ethylhexyl acrylate, 9 to 17 wt. % of alkyl methacrylate, 1 to 3 wt. % of monoalkyl fumarate and the remaining amount is ethyl acrylate. This acrylic rubber improves hydrolysis resistance by introducing a specific alkyl acrylic monomer with extremely low hydrolysis property i.e. low hydrophilicity, and at the same time satisfies all of oil resistance, cold resistance, and hydrolysis resistance in a well-balanced manner.

An acrylic rubber contains a copolymer of a monomer mixture of: 25 to 46 wt. % of alkoxyalkyl acrylate, 23 to 37 wt. % of 2-ethylhexyl acrylate, 9 to 17 wt. % of alkyl methacrylate, 1 to 3 wt. % of monoalkyl fumarate and the remaining amount is ethyl acrylate. This acrylic rubber improves hydrolysis resistance by introducing a specific alkyl acrylic monomer with extremely low hydrolysis property i.e. low hydrophilicity, and at the same time satisfies all of oil resistance, cold resistance, and hydrolysis resistance in a well-balanced manner.

One aspect of the present invention is an acrylic rubber containing ethyl acrylate and n-butyl acrylate as monomer units and containing a toluene-insoluble component, wherein a mass ratio of a content of the ethyl acrylate to a content of the n-butyl acrylate is 2 or more, and a content of the toluene-insoluble component is 5% by mass or less based on a total amount of the acrylic rubber.

One aspect of the present invention is an acrylic rubber containing ethyl acrylate and n-butyl acrylate as monomer units and containing a toluene-insoluble component, wherein a mass ratio of a content of the ethyl acrylate to a content of the n-butyl acrylate is 2 or more, and a content of the toluene-insoluble component is 5% by mass or less based on a total amount of the acrylic rubber.