# Flow-Line-Reducing Tetrahedral Metal Effect Pigments for Injection Molding: A Yield-Rate-Improved Particle Manufacturing Method Based on Soft UVImprint Lithography

## TL;DR

A new method for making tetrahedral metal pigment particles reduces flowlines in injection molding and improves manufacturing yield.

## Contribution

A novel UV imprint lithography-based method for manufacturing tetrahedral metal effect pigments with improved yield and shape retention.

## Key findings

- Tetrahedral particles made with UV-cured thermoset polymer maintain shape during injection molding.
- The new method eliminates high reject rates caused by particle adhesion in previous processes.
- The process supports potential automation via roll-to-roll manufacturing.

## Abstract

This publication presents an improved manufacturing method for tetrahedral metal effect pigment particles that demonstrates reduced flowlines in injection-molded polymer components compared with conventional platelet-shaped pigment particles. The previously published cold forming process for tetrahedral particles, made entirely from aluminum, faced manufacturing challenges, resulting in a high reject rate due to particle adhesion to the micro-structured mold roller. In contrast, this study introduces a new manufacturing method for tetrahedral particles, now consisting of metallized UV-cured thermoset polymer. These particles, dispersed in amorphous matrix thermoplastics, have shown to maintain their shape during the injection molding process. The manufacturing technique for these novel particles is based on UV imprint lithography, omitting the reject rates compared with the previously presented cold rolling process of tetrahedral full aluminum particles. Thus, the novel manufacturing technique for tetrahedral pigment particles shows increased potential for automation through roll-to-roll manufacturing in the future.