Transfer sheet for the thermal dry impression of cellulose fibers

Claim 1

A transfer sheet for the heat transfer printing of textile materials which contain cellulosic fibers pre-treated for swelling, said sheets consisting essentially of an inert, flexible substrate having a release coating on a least one-surface thereof, said release coating carrying a dyestuff-containing coating or design, wherein the dyestuff-containing coating or design is a mixture containing (a) a binder containing at least one high molecular, organic, film forming substance having a softening point between 50° and 150° C., said binder selected from the group consisting of naturally occuring resins, maleinate resins, phenolic resins, urea resins, polymerized unsaturated hydrocarbons, epoxy resins, polymide resins and rosin modified resins, and (b) at least one disperse or vat dyestuff, said dyestuff does not sublimate in conventional heat transfer printing, said dyestuff having an optical absorptivity not exceeding 0.3 when in a boiling, saturated solution in 0.1 molar aqueous sodium carbonate and (i) that the dyestuff is transferred from a transfer paper normally used in heat transfer printing, at a rate of not more than 40% by weight when said transfer sheet is pressed against the textile material under a contact pressure of 5 kPa and maintained under atmospheric air pressure for 30 seconds at 200° C., the textile material being swollen with water and whose swollen state has been preserved after drying by a polyglycol or a polyglycol derivative, and (ii) that the dyestuff is transferred at a rate of more than 60% by weight when said transfer sheet is pressed against the textile material under a contact pressure of 50 kPa, and at an atmospheric air pressure of 10 kPa, for 30 seconds at 230° C.