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Mass Thermal Transfer Printing Disclosure Number: IPCOM000014604D
Publication Date: 2003-Jun-19

Publishing Venue

The Prior Art Database


Mass Thermal Transfer Printing on Release Coatings Pressure-sensitive adhesive tape rolls are widely known within a variety of industries and for a wide variety of applications. Typically, a pressure sensitive adhesive comprises a plastic or paper base having a first side and a second side. The second side of the base has a pressure sensitive adhesive layer. In order to prevent the pressure sensitive adhesive layer sticking to the first side of the base when the tape is rolled up, a release layer may be present on the first side of the base. Typical release layers well-known in the art include silicone release layers, carbamate polymers or other polyurethane release layers, and silicone-polyurea release layers. Also known are polyolefin release layers which may include polyethylene, polypropylene, copolymers of ethylene and propylene and blends of these polymers. Other polyolefin release layers may include halogenated polyolefins such as chlorinated polyethylenes. The release layers can be applied to the base (or the base applied to the release layer) by a number of techniques well known in the art such as solvent coating, aqueous solution coating, aqueous emulsion or dispersion coating, hot-melt coating, hot-melt extrusion, and lamination. It is also well-known that a release layer may not be required in order to be able to unwind the tape if the base and adhesive layer are selected so as the pressure sensitive adhesive will not strongly adhere to the first side of the base. In such a case, a treatment may be required to allow the adhesive to adhere to the second side of the base. Such a treatment could be prime layer, an additional layer between the adhesive layer and the base, or corona treatment of the second side of the base. It is known in the industry that pressure sensitive adhesive tapes can be directly printed with mass thermal transfer. The topside of the tape (e.g. the surface from which the adhesive releases during the unwinding of the tape) is the surface which is printed with the thermal transfer inks. Two different classes of topside materials have been shown to be printable with mass thermal transfer inks; olefinic (polyolefin) film surfaces and base films with release layers. The present investigators have determined that a critical minimum thickness of release layer is required to obtain good print quality characteristics when the release coating is applied to bases that are not printable without the release layer. If the critical thickness of the release layer is exceeded, good print quality is obtained with a variety of different types of thermal transfer ribbons such as resin-based ribbons, wax-based ribbons or hybrid ribbons (mass thermal transfer ribbons comprising at least one synthetic resins and at least one type of wax). The specific critical minimum thickness in any given print system may depend on the structure and composition of the tape (for example, the type of release coating, the type of base material, the type of adhesive) or the type of printer. The critical thickness for a given tape and printer may easily be determined with minimum experimentation by one of ordinary skill in the art. The investigators have determined that utilizing a urethane (polycarbamate) release layer, a critical layer thickness of about 400 angstroms was identified. Below about 400 angstroms thickness, the polycarbamate release layer either was not printable or had very poor printed quality with resin-based mass thermal transfer inks. Above about 400 angstroms thickness of polycarbamate release layer, good to excellent print quality was achieved. Good print quality includes being able to print barcodes which scan well with a barcode scanner, and achieving images with a good degree of rub resistance.