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AssigneesDai Nippon Insatsu Kabushiki Kaisha, Sekisui Kagaku Kogyo Kabushiki Kaisha
InventorsJumpei Kanto, Masanori Akada, Katsuhiro Kamakari, Kenichi Asahina, Katsuaki Sakashita, Yoshihisa Watanabe
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A heat transfer sheet comprises a substrate sheet and a heat transfer layer laminated on the substrate sheet and containing a dye which can be caused to migrate by heating to be transferred onto a transferable sheet, said heat transfer sheet containing a polyvinyl acetacetal resin as a binder component, the acetal moiety of said polyvinyl acetacetal resin being 50% by weight or more based on the total amount of the resin, and 80% by weight or more of said acetal moiety comprising polyvinyl acetacetal. A process for producing a polyvinyl acetacetal resin by the reaction of a polyvinyl alcohol and acetaldehyde in an aqueous phase in the presence of 4 to 10% by weight of an acid catalyst comprises initiating precipitation of an acetalated product by maintaining the reaction system at a temperature of 8.degree. to 17.degree. C. for 30 minutes or longer, and then maintaining said reaction at a temperature of 25.degree. to 40.degree. C.
A heat transfer sheet comprising a substrate sheet and a heat transfer layer laminated on the substrate sheet and containing a dye which can be caused to migrate by heating to be transferred onto a transfer receptor sheet, said heat transfer sheet containing a polyvinyl acetacetal resin as a binder component, the acetalated moiety of said polyvinyl acetacetal resin being 50% by weight or more based on the total amount of said resin, and 80% by weight or more of the repeating units of said resin are the acetal acetalated moiety.
Dependencies are inferred from the claim text.