Sunrez and Light Cure Resin Technology

Resin light curing technology has been available in Europe for the last 25 years, and in the U.S, for the past 20 years. Sunrez went to Germany to bring this technology back to solve a series of problems that exist with typical peroxide curing of unsaturated resin. It was our years of experience in traditional composite fabrication that provided our knowledge of the shortcomings in peroxide curing and the advantages provided by light curing.

Sunrez Resin technology diagram. Sunrez developed light cure resin technology provides a RAPID and CONTROLLED cure of polyester, vinylester, and urethane systems measured in seconds instead of minutes or hours. The advantages provided by Light Curing Resin Technology, is a breakthrough that allows polyester, vinylester, and urethane resin to be used in new applications and fabricated via new methods, opening up many new opportunities in both coatings and composites.


Light Curing Polyester, Vinylester, and Urethane Resins

Light curing of polyester, vinylester, and urethane resins is not a new technology, but the rapid and controlled curing of these resins is new. Twenty five years ago a light cure initiator for rapid curing of polyester and vinylester resins was developed at laboratories in Germany. Sunrez has continually modified and improved this light curing technology expanding it into new areas and extending it from thin coatings to very thick glass reinforced laminates. Total cure times of 3 minutes are typical for parts of 3/16” and under 10 minutes for parts 3/4” thick, using open molds and hand lay-up, or machine application of the resin and glass. Additionally new fabrication technologies and application areas are possible for both polyester and vinylester laminates. Light curing of resins is independent of temperature, therefore cure time of parts, is constant whether cured in either hot or cold weather. Another plus is that styrene emissions can be reduced by up to 95% depending on the fabrication method used. (This is based on fabrication processes patented by Sunrez). The reduction in styrene emissions results from the cure mechanism which occurs from the top surface down.

Laboratory tests have shown that up to a 10% increase in physical properties have been seen using Sunrez light curing technology versus MEKP cure of the same resin systems. This difference results from the more complete cure of the resin system with the Sunrez photo-initiator systems.


Advantages of Light Curing Resin Technology

  • Long shelf life of photo-initiated resins
  • Unlimited pot life for resins (no gel or cure until exposed to UV-A light)
  • No wasted resin in the can (as seen with peroxide catalyzed materials)
  • Significant reduction in resin waste and processing cost
  • Rapid and complete cure at ambient temperature (hot or cold)
  • Prepregs and putties can be used for repair outside all year long
  • No secondary cure required when using vinylester resins
  • Reduction of internal stresses in cured part
  • Significant reduction of styrene emissions in the workplace.
  • No residual styrene smell or taste on the fiberglass parts
  • Vacuum forming operations are now possible with fiberglass
  • Safe light spectrum 380-410 nm (compared to UV-B and UV-C)
  • Resin works as well with sunlight as with UV-A lights
  • No mixing or metering operations required and no “runaway exotherm”
  • Quicker demold times 3 minutes (no “GREEN” parts)
  • Complicated parts that would normally require 30-40 minutes to be built with a chopper gun can be built in under 5 minutes
  • Secondary finishes can be included on the part