Method for making molded printing plates

Abstract

Abstract AN IMPROVED DUPLICATE PRINTING PLATE OF THE LETTER PRESS CLASS IS MADE FROM A GELLED SHEET OF FLUID PRINTING PLATE MATERIAL. THE GELLED SHEET IS REQUIRED TO BE PREPARED UNDER SELECTIVELY CONTROLLED HEATING CONDITIONS. THE SELECTIVELY HEATED PRINTING PLATE MATERIAL THUS PRODUCED IS CHARACTERIZED BY BODY AND HANDLING STRENGTH SUCH THAT IT MAY BE MANIPULATED AND CONTAINED IN AN EVACUTATED MOLDING PRESS. IN THE PRESS THE MATERIAL IS SUBJECTED TO HEAT AND PRESSURE WHILE IN CONTACT WOTH A FEMALE MOLD. AN IMPORTANT CONSIDERATION IS CONTROL OF HEATING TO MAINTAIN THE GELLED SHEET IN A STATE OF LIMITED PLASTICITY SO THAT COLD FLOWING IS POSSIBLE AT THE TIME THE SHEET IS INTRODUCED INTO THE PRESS. IN THIS LIMITED STATE OF PLASTICITY THE MATERIAL THROUGHOUT ITS LAYER THICKNESS MAY, UNDER SUITABLE HEAT AND PRESSURE, BE DISPLACED INTO INTIMATE CONTACT WITH THE MOLD DEPRESSIONS AT ALL POINTS THEREIN. CONTINUING HEAT AND PRESSURE THEN CONVERTS THE DISPLACED PLASTIC OR GELLED MATERIAL INTO A COMPLETELY FUSED AND CURED RUBBER-LIKE MASS TO PRODUCE A PERMANENTLY MOLDED LETTER PRESS PRINTING PLATE WHICH IS FREE FROM STRESSES.

Inventors

• 👤 John A Willett

Bibliographic Details