| 摘要 |
PURPOSE: To obtain a multistage polymer useful for e.g. protective films or sheets excellent in transparency and resistance to whitening under stress and improved in weatherability, copolymerized with an ultraviolet-light-absorbing monomer of specific structure. CONSTITUTION: This multistage polymer >=50wt.% in gel content is obtained by multistage seed emulsion polymerization in the order of component A→component B→component D→component C. These components are as follows: (A) a 1st stage polymer obtained by polymerization between (i) a 1-8C alkyl acrylate or (ii) a 1-4C alkyl methacrylate, (iii) a monomer having a copolymerizable double bond, (iv) a polyfunctional monomer, (v) a graft crossing agent and (vi) an ultraviolet-light-absorbing monomer of the formula (R is H or methyl) in specified proportions; (B) a 2nd stage polymer obtained by polymerization between the components (i), (III), (iv), (v) and (vi) in specified proportions; (C) the final stage polymer >=50 deg.C in glass transition temperature obtained by polymerization between the components (ii), (iii) and (iv) in specified proportions; and (D) an intermediate stage polymer obtained by polymerization between the components (i), (ii), (iii), (iv), (v) and (vi) in specified proportions.
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