PRODUCTION METHOD FOR RESIN SINTERED BODY

To make it possible to eliminate an unevenly colored area on a surface of a resin sintered body, to ensure that the surface is uniformly and sufficiently colored as required, and to make the surface look nice and smooth, when producing the resin sintered body by sintering a resin powder of thermoplastic resin.SOLUTION: A method for producing a resin sintered body 1 by applying an ink 3 to a resin powder 2 of thermoplastic resin and sintering it includes a process of immersing a sintered intermediate resin 1m sintered entirely with non-uniform colored areas on its surface in a surface treatment solution containing sulfuric acid and a chromic anhydride at a concentration of 300 g/L or more of the chromic anhydride for at least 5 minutes. Suitably, the concentration of the sulfuric acid and the chromic anhydride in the surface treatment solution should be 184 g/L to 368 g/L and 300 g/L to 500 g/L, respectively.SELECTED DRAWING: Figure 1 【課題】熱可塑性樹脂の樹脂粉末を焼結して樹脂焼結体を製造する際に、表面の不均一な着色領域を無くし、樹脂焼結体の表面を均一且つ十分に必要な着色が施された状態にすることができると共に、樹脂焼結体の表面を見栄えの良い平滑な状態にすることができる。【解決手段】熱可塑性樹脂の樹脂粉末２にインク３を塗布して焼結させる樹脂焼結体１を製造する方法であり、表面に不均一な着色領域を有する全体が焼結済みの中間樹脂焼結体１ｍを、硫酸と無水クロム酸を含有し、無水クロム酸の濃度が３００ｇ／Ｌ以上である表面処理液に５分以上浸漬する工程を備え、好適には表面処理液の硫酸の濃度を１８４ｇ／Ｌ～３６８ｇ／Ｌ、無水クロム酸の濃度を３００ｇ／Ｌ～５００ｇ／Ｌとする。【選択図】図１