Method for the production of an embossing roller for the continuous embossing of the surface of a thermoplastic film

Claim 1

In a method for the production of a negative embossing roller for the continuous embossing of a thermoplastic film in which a synthetic resin is poured or spread as a uniformly thick coating onto a grain-patterned surface and then hardened into an embossing matrix which is then peeled off the grain pattern, the improvement comprising wrapping a generally-rectangular sheet of leather with the grain pattern out, and opposed edges of the sheet abutting, around a roller whose diameter corresponds esentially to the diameter of the embossing roller to be produced, so that the entire surface of the roller is covered, spreading liquid silicone rubber on the grain pattern, hardening the rubber while in contact with said grain pattern to form a tubular embossing matrix, having discontinuities in the grain design where said opposed edges abut, and continuous portions adjacent said abutting edges, embossing at elevated temperature between a pair of spaced rollers the surface of a tubular thermoplastic film mounted on one roller of said tubular embossing matrix mounted on the other roller of said pair, embossing again the surface of the thermoplastic film by contact with said continuous portions of the embossing roller in the areas along the abutting edges of the natural grain pattern on the roller, while gradually increasing the pressure as the rolls approach the bight and then decreasing the embossing pressure as said abutting edges pass through the bight of said spaced rollers, thus producing an endless positive impression without discontinuities in the grain pattern, spreading liquid silicone rubber onto the positive impression, hardening the rubber to provide a negative embossing matrix, peeling the matrix from the positive impression, and adhering the negative embossing matrix, embossed side out, onto the circumferential surface of the embossing roller.