PROBLEM TO BE SOLVED: To provide a molded article excellent in mechanical properties, especially a denture base and a mouthpiece.SOLUTION: There is provided a composition obtained by mixing a powder agent of a polymer (A) and a solution of a monomer (B) in the presence of a polymerization initiator (C), where mixture ratio (g/ml) of the powder agent of the polymer (A) to the solution of the monomer (B) is 1.5 to 2.3, the polymer (A) contains a methyl methacrylate unit of 80 mass% or more, the monomer (B) contains methyl methacrylate (b1) and tri(meth)acrylate of aliphatic triol having 3 to 10 carbon atoms (b2), total amount of (b1) and (b2) in the monomer (B) is 80 mass% or more and mass ratio of (b2) to (b1), (b2/b1) is 3/97 to 60/40.SELECTED DRAWING: Figure 2COPYRIGHT: (C)2017,JPO&INPIT【課題】機械的特性に優れた成形品、特に、義歯床やマウスピースを提供する。【解決手段】重合体(A)の粉剤と単量体(B)の液剤とを重合開始剤(C)の存在下で混合してなる組成物であって;単量体(B)の液剤に対する重合体(A)の粉剤の混合比(g/ml)が1.5~2.3であり、重合体(A)が、メチルメタクリレート単位を80質量%以上含有し、単量体(B)が、メチルメタクリレート(b1)及び炭素数3~10の脂肪族トリオールのトリ(メタ)アクリレート(b2)を含有し、単量体(B)における、(b1)及び(b2)の合計量が80質量%以上であり、かつ(b1)に対する(b2)の質量比(b2/b1)が3/97~60/40である組成物。【選択図】図2
