CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application is a national stage entry under 35 U.S.C. § 371 of International Application No. PCT/KR2019/015015 filed on Nov. 7, 2019, which claims priority to Korean Patent Application No. 10-2018-0161342, filed on Dec. 13, 2018, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an acrylic copolymer, and more particularly, to an acrylic copolymer having an excellent workability and durability, a method of preparing the same, and an acrylic copolymer composition including the same.

BACKGROUND ART

A rubber component used in a vehicle is only 5% of the entire weight of the vehicle, but is mainly used for an important part affecting performance of the vehicle. The rubber component is considered as an important component such as a part applied to a portion at which vibration and noise are generated and a part applied to a portion at which heat resistance and oil resistance are required, due to its characteristics. In particular, a material having an excellent heat resistance and oil resistance is required for an engine of a small-sized vehicle requiring a high output.

Among various specific rubbers, acrylic rubber is rubber having (meth)acrylic acid alkyl ester as a main monomer unit, and has an excellent heat resistance and oil resistance. Accordingly, in vehicle related fields and the like, the acrylic rubber has been widely used as a material of a rubber component not only for a seal, a hose, a tube, or a belt but also for an adhesive. Elasticity is imparted to acrylic rubber through crosslinking so as to be used as a rubber component, and to this end, crosslinking monomers each having an active crosslinking site are copolymerized in the acrylic rubber. In general, crosslinking acrylic rubber in which the crosslinking monomers are copolymerized is mixed with a filling material such as carbon black or a crosslinking agent to prepare a crosslinking acrylic rubber composition. The crosslinking acrylic rubber composition is molded in a mold having a desired shape and used for various uses.

As such, it is required for the crosslinking acrylic rubber used for various uses to have an excellent roll mill workability or molding workability in order to be molded as a molded product having a desired shape as well as an excellent heat resistance and oil resistance. In addition, in order to implement durability suitable for the above uses, it is required for acrylic rubber to have a high crosslinking density. However, crosslinking is generated during a preparation process due to characteristics of crosslinking acrylic rubber, such that uniformity of a crosslinking monomer deteriorates, which results in deterioration of workability and durability.

DISCLOSURE

Technical Problem

In order to solve the problems mentioned in the background art, an object of the present invention is to improve workability and durability of an acrylic copolymer through uniform crosslinking when preparing the acrylic copolymer.

That is, an object of the present invention is to provide an acrylic copolymer composition having an excellent workability and durability by including an acrylic copolymer prepared by lowering self-crosslinking of the acrylic copolymer to lower crosslinking of a polymer and controlling a reaction rate to have a uniform distribution of crosslinking monomers.

Technical Solution

In one general aspect, there is provided an acrylic copolymer including: a main monomer-derived repeating unit; and a chain transfer agent-derived part, wherein the main monomer-derived repeating unit includes a (meth)acrylic acid alkyl ester monomer-derived repeating unit, a (meth)acrylic acid alkoxy alkyl ester monomer-derived repeating unit, and a crosslinking monomer-derived repeating unit, the chain transfer agent-derived part is derived from a chain transfer agent having a carbonothioylthio group, and the chain transfer agent-derived part is included in an amount of 0.03 parts by weight to 0.08 parts by weight with respect to 100 parts by weight of the main monomer-derived repeating unit.

In another general aspect, there is provided a method of preparing an acrylic copolymer, the method including: a step of preparing a main monomer mixture including a (meth)acrylic acid alkyl ester monomer, a (meth)acrylic acid alkoxy alkyl ester monomer, and a crosslinking monomer; and a step of adding 0.03 parts by weight to 0.08 parts by weight of a chain transfer agent with respect to 100 parts by weight of the main monomer mixture and performing polymerization, wherein the chain transfer agent has a carbonothioylthio group.

In still another aspect, there is provided an acrylic copolymer composition including the acrylic copolymer and a filler.

Advantageous Effects

The acrylic copolymer including a chain transfer agent according to the present invention induces a chain transfer reaction and lowers self-crosslinking of a polymer to lower crosslinking of the polymer, thereby having an excellent workability. In addition, the acrylic copolymer including a chain transfer agent according to the present invention controls a polymerization reaction rate to have a uniform distribution of crosslinking monomers, thereby having an excellent durability through the uniform crosslinking.

