March, 2003

Blending resins provide the formulator with a valuable tool, helping to solve a variety of processing and field performance issues. Sporadically, through the years, we have evaluated a number of blending resins to assess their unique characteristics. We felt that, due to the introduction of a number of new resins, it would be beneficial to conduct a more complete study of all available foreign and domestic blending resins at this time.

The blending resins in our study ranged in ‘K Value’ from 49 to 77. We included copolymer blending resins, varying in comonomer level from 4 to 14%. We evaluated these materials for viscosity, both Brookfield and Severs, viscosity stability, and development of tensile strength, tear resistance, and elongation at various fusion temperatures. We also compared the heat stability of the resins in a formulation which was stabilized with 1 PHR of a tin mercaptide stabilizer. Most of the work was done in a formulation containing 60 PHR Dispersion resin, 40 PHR of the blending resin and 50 PHR of DINP. In one experiment, the level of blending resin was also varied from 10 to 40 PHR, and the variation in viscosity as well as physical properties were compared.

We did not consider it of value to give an absolute rating as to which resin is best or worst, as it may vary from application to application. The processing method may dictate the need for different resins, even though the end product may be similar.

The use of bending resins is a valuable tool for the compounder and processor. The knowledge of their differences may be helpful in assisting in the resolution of some processing problems or providing a more economical, functional product.

We would appreciate the opportunity to help you in interpreting our study and relating it to your specific issues.