Improve UV-Curable Formulations with Elvacite® Resins

While these formulations vary depending on end-use application, they generally share a common set of ingredients, including monomers, oligomers, additives, and photoinitiators. As in any coating, ink, or adhesive formulation, it is important to select materials that add desired functionalities while balancing formulation costs. Elvacite® acrylic resins, manufactured by Mitsubishi Chemical Group in Pasadena, TX, are additives for UV- and EB-curable systems that exhibit a broad range of solubility in various monomers. When used to replace oligomer content, they provide a host of performance enhancements and potential cost-saving benefits.

 

Elvacite® Resins for Radiation-Curable Systems

Elvacite® acrylic resins function as passive resins in radiation-curable formulations. They have been designed specifically with novel polymer chemistry that imparts a unique reactive macromolecular design in UV- and EB-curable formulations such as wood and plastic coatings and screen inks. In general, formulators gain the following benefits using Elvacite® resins.

 

• Better control over film shrinkage
• Enhanced film flexibility
• Increased substrate and intercoat adhesion properties
• Improvements to viscosity and flowability
• Economical improvements by replacing costly acrylate-functionalized oligomers

To examine the functional improvements Elvacite® makes in radiation-curable systems, Elvacite® 4026 was used to replace various types of oligomers in three different UV-curable formulations. Changes in physical properties were measured between formulations with and without Elvacite®.

Urethane Acrylate Oligomer Replacement

UV-curable paper coating formulations were prepared using CN965 or EBECRYL® 245 urethane acrylate oligomers. Elvacite® 4026 replaced 50% by weight of each oligomer to examine film hardness and resistance to solvents. The details of these formulations and test results are below.

With CN965 Acrylate

With EBECRYL® 245 Acrylate

Partially replacing both the urethane acrylate oligomers with Elvacite® 4026 indicated a relatively small increase in formulation viscosity, a significant boost to curing speed, and enhanced solvent resistance and hardness. This suggests that Elvacite® 4026 can help increase the productivity and durability of formulations while maintaining a workable viscosity when applied.

Polyester and Urethane Acrylate Oligomer Replacement

Next, UV-curable wood coating control formulations were prepared with EBECRYL® 245 aliphatic urethane acrylate and EBECRYL® 657 polyester acrylate oligomers. This time, a formulation was made where Elvacite® 4026 replaced these oligomers entirely. These formulations, listed below, were blended with the control formulations in different ratios to test for changes in viscosity, adhesion, and stain resistance.
 

P = shoe polish, Ma = marker pen, Mu = mustard, C = coffee

The data above suggest that while the Elvacite® 4026 replacement increases the viscosity of the formulation, it also increases adhesion to wood surfaces and markedly improves stain resistance. For suitable application of this UV-curable formulation, the 60:40 ratio may offer the best balance in terms of performance improvements and workable viscosity.

Epoxy and Urethane Acrylate Oligomer Replacement

Finally, an epoxy–urethane UV-curable coating formulation was prepared using EBECRYL® 210 aromatic urethane acrylate and EBECRYL® 605 epoxy acrylate oligomers. As in the formulation above, Elvacite® 4026 replaced these oligomers entirely to create a blend between the formulation containing the oligomers and the formulation containing Elvacite® 4026. 
 

P = shoe polish, Ma = marker pen, Mu = mustard, C = coffee

In this case, the original formulation with the oligomers had excellent adhesion and stain resistance. Replacing the oligomers with Elvacite® 4026 by blending the formulations up to a 50:50 ratio did not detract from any of the adhesion or stain resistance properties, indicating that Elvacite® 4026 can be a good replacement from a cost-savings standpoint for some oligomers.

Formulation Guidelines and Grade Selection

Generally, the best results from formulating with Elvacite® have been observed by creating Elvacite® resin-to-oligomer ratios between 30:70 and 50:50 by percent weight. Elvacite® resins should be dissolved in acrylate monomers prior to adding other formulation components. While only Elvacite® 4026 has been featured thus far in this article, many other Elvacite® grades can be used to provide performance improvements or replace oligomer content in UV-curable formulations. Below is a list of options and their general solubility ratings in common monomers. Click on each Elvacite® grade number below to learn more about it.

NA = no data

Summary

UV-curable coating, ink, and adhesive formulations confer many benefits over solvent- or water-based formulations but can be quite costly due to ingredients such as photoinitiators and functionalized oligomers. Elvacite® acrylic resins are ideal additives that can increase adhesion, cure speed, and durability when used as a partial replacement for oligomers in these formulations. Formulation costs may be reduced by requiring less costly oligomers to be integrated. Click below to speak to one of our formulation experts about your application and request a sample of Elvacite®.

SURFYNOL® is a trademark of Evonik
EBECRYL® is a trademark of Allnex.
Darocur® is a trademark of BASF.