To provide a preparation method of a copolymer which contains a carboxy group-containing acrylic monomer and is excellent in handleability and thermal stability.
The preparation method of the thermoplastic copolymer comprises two steps, i.e. a polymerization step (I) and a washing step (II). In the polymerization step (I), a copolymer slurry is obtained by copolymerizing a monomer mixture containing the carboxy group-containing acrylic monomer and other acrylic monomers copolymerizable with the same in an organic solvent (B) which contains no aromatic group and dissolves the monomer mixture, wherein the solubility of the carboxy group-containing copolymer (A) is ≤1 g/100 g. In the washing step (II), the copolymer (A) is obtained by subjecting the copolymer slurry obtained through the polymerization step (I) to a solid-liquid separation, adding water and washing the polymer (A) at 50-120°C and performing solid-liquid separation again at 50-120°C.
MATSUMOTO HIDEKI
YAMANAKA TORU
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