Current Status of Polyurethanes in the Printing Industry.

Polyurethane printing roller applications date back about ten years; in this time they have assumed significance, particularly in the letterpress field. Increased press speeds demand rollers of better physical properties than the old gelatin or vulcanized oil. Synthetic rubber filled the need for durability but is limited by washup difficulties, decreased printing quality, and hardening in service. Polyurethane rollers in printing hardnesses have excellent abrasion and cutting resistance, compression set, and oil resistance. Casting in honed molds produces a glass-smooth surface, facilitating washup and resulting in superior ink film control and printing quality. Furthermore the urethane roller is 100 percent solids - thus avoiding the common problem of plasticizer extraction and hardening in service. Original polyurethane rollers suffered from poor high temperature-high humidity resistance, resulting in lost resilience. However, recent research on this problem has produced a material with triple the previous resistance to deadening. These rollers will be introduced commercially in the summer of 1963. This break-through could mean the eventual complete replacement of rubber rollers in letterpress printing.