Abstract: A coating agent comprising an amine-modified polyvinyl alcohol and at least one compound (A) selected from the group consisting of a compound (A1) represented by formula (1) below and a compound (A2) represented by formula (2) below: wherein R1 to R6 and R11 to R18 each independently represent any of a carboxyl group, a sulfo group, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, and a halogen atom, one of R1 to R6 is any of a carboxyl group and a sulfo group, two or three of R1 to R6 are each a hydroxyl group, one of R11 to R18 is any of a carboxyl group and a sulfo group, and two or three of R11 to R18 are each a hydroxyl group.

Abstract: A resin composition containing a polyvinyl alcohol-based resin, 0.1% by mass or more and 1.2% by mass or less of a surfactant, and at least any one of an inorganic filler and silicone particles, wherein the resin composition is free of a plasticizer or comprises 5.0% by mass or less of a plasticizer, and satisfies at least any one of the following requirements (1) and (2). (1) The content of the inorganic filler is 1% by mass or more and 30% by mass or less (2) The content of the silicone particles is 0.01% by mass or more and 0.

Abstract: Provided is a resin for core used for injection molding, with which an inner surface of an outer molded body is less likely to be roughened, and an inner surface of a finally obtained molded body is smooth and less likely to have chipping. The resin for core includes a polyvinyl alcohol-based resin, used for an application in which a core is dissolved in water after an outer molded body is molded in an injection molding process, and includes an easy stripping agent that enhances easy stripping properties when the resin for core dissolves in a proportion of more than 0.1 wt % and less than 1.2 wt %.