(Meth)acrylic polymers and their manufacturing methods, thermoplastic resin compositions and plasticizers

Abstract

This invention relates to a (meth)acrylic acid polymer, which has a ring structure at the end of the polymer having substituents bonded to an ester ring with 5 to 7 ring elements, and satisfies requirements (I), (II), or (III). Requirements (I): The ring structure is represented by general formula (1A), and the content of the aforementioned ring structure relative to all repeating units of the polymer is 32 mol% or more. In formula (1A), R1 is an alkyl group having 1 to 3 carbon atoms; R2 is a hydrogen atom, methyl, or ethyl; R3 is a single bond or methylene. However, when R3 is a single bond, R1 and R2 are not both methyl. Requirements (II): The ring structure is represented by general formula (1B). Requirements (III): The ring structure is represented by general formula (1C), and the content of the ring structure relative to all repeating units of the polymer is 60 mol% or more; and it is different from copolymers of 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate.