Selection of Photopolymer for Microrelief Formation by Two-Stage Cold Stamping Method

Abstract

Microrelief formation by embossing the master matrix (with the period of 3.5 μm and depth of 1 μm) on photopolymer
coatings and its application for large areas embossing technology has been investigated. The method embodies the direct
contact microrelief cold stamping and two stages of UV curing processes. The purpose of the initial (stage I) UV curing
is to obtain the coating of such hardness that periodical structure with the precise geometry could be embossed. The aim
of the final (stage II) UV curing is to stabilize the mechanical properties of photopolymer coating and to fix the
geometry of embossed microrelief. The investigations were performed using three types of acrylate based commercial
photopolymers. The wetting and mechanical properties, surface topography of photopolymer coatings, diffraction
efficiency and geometry of embossed periodical structures have been investigated in order to find the effective durations
for both UV curing stages and define parameters of replication process. The quality of replicated microrelief was found
to be in great dependence on the photopolymer type, its wetting properties, hardness and surface structure of the coatings
and parameters of replication process.