Patent ID: 6010609
Filing Date: 2000-01-04
Classification: B29C,B29L,G02B,Y10S

Abstract:
A method of making a cube-corner microprism master mold which comprises stacking a plurality of flat sheets having two mutually parallel major surfaces, cutting V-shaped grooves on one lateral surface of the resulting flat sheet stack in a direction perpendicular to the major surfaces and at a fixed pitch to form a series of successive roof-shaped projections having a vertical angle of about 90.degree., and then shifting the flat sheets so that the vertices of the roof-shaped projections formed on each flat sheet meet the bottoms of the V-shaped grooves formed on an adjacent flat sheet, characterized in that the flat sheets used have a thickness of 50 to 500 .mu.m and in that the flat sheets are made of a synthetic resin having a Rockwell hardness of not less than 70.