| 摘要 |
1451338 Heat-sensitive transfer material MINNESOTA MINING & Mfg CO 21 Dec 1973 [29 Nov 1973] 59470/73 Heading G2C Graphics are formed by providing an accepting tape comprising a layer of latent adhesive material which is non-tacky at room temperature but is softened and activated when heated, a donor web, a friable layer of microgranules releasably adhered to the donor web, either (A) at least one of the layers containing a radiation absorbing pigment or (B) at least one of the tape and web supporting a separate coating of a radiation absorbing pigment, and at least one of the tape and web being transparent to radiant energy from one exterior surface at least to the pigment coating, positioning the layers of the tape and web in face-to-face contact to provide a composite strip material, irradiating the composite strip material through the exterior surface imagewise to heat the radiation absorbing pigment above the softening range of the adhesive material whereby the layer of adhesive material selectively softens and adheres to the layer of microgranules, and separating the accepting tape and donor web to carry microgranules to the accepting tape imagewise. The mircrogranules may comprise a thermoplastic resin which softens at a temperature above the softening range of the adhesive material, in which case the separated accepting tape and/or donor web may be placed with their microgranules contacting a support, heated to adhere the resin to the support and the tape or web may be separated leaving microgranules adhering to the support. The pigment may be carbon black. The thermoplastic resin may be an acidmodified ethylene/vinyl acetate copolymer. The accepting tape may be coated with a pressuresensitive adhesive protected by a silicone-treated paper overlay (see Example 7) on the side opposite the microgranules. The microgranular layer may contain titanium dioxide. The microgranules may have an average diameter not greater than 5 microns. The adhesive material may comprise a paraffin wax, equal parts by weight of a paraffin wax, a polymerized hydrocarbon and an ethylene/vinyl acetate copolymer, a paraffin wax and a polymerized hydrocarbon or a copolymer of equivalent amounts of bisphenol A and its diglycidyl ether. The donor web and accepting tape may comprise biaxially-oriented polyethylene terephthalate 0À001 inch thick. The accepting tape may consist only'of the adhesive material. |
