News from Harwick
Epolene Polymers for the Rubber Industry
In 2006, Westlake Chemical Corporation purchased the Epolene® low molecular weight polyethylene and polypropylene wax business from Eastman Chemical, introducing them into the rubber industry. Westlake has been known more prominently in the plastics business as the largest producer of low-density polyethylene (LDPE) in North America.
In 2009, the Epolene line celebrated 50 years of formulation success in many diverse applications and markets. Harwick Standard has promoted the Epolene line of low molecular weight polyethylene and polypropylene waxes since 1967. These time-tested products are based on a proprietary high-pressure, free radical technology that directly creates low molecular weight polyethylene products that perform as internal-lubricant/process aids and external mold release agents in various polymeric systems. These non-polar grades are soft with high penetration hardness values and low melt points that allow flow out, coating, and lubrication of the polymer chains. Epolenes are typically used in non-polar elastomers such as EPDM, synthetic Polyisoprene, Natural Rubber, Polybutadiene Rubber, NBR, SBR and Block Copolymers as well as in hot melt adhesives.
The Epolene product line is divided into 3 major classes of low molecular weight polymers: N types - Normal (non-emulsifiable), C types – Coating, and E types - Emulsifiable. The rubber industry tends to utilize the N types and C types. The flagship N-type product is Epolene N-34P (powder) which as a low-density product with a relatively low melt point (103°C) is utilized in EPDM compounds and block copolymers as well as Natural Rubber. Epolene N-11P and N-14P have demonstrated the ease with which they bloom to rubber surfaces to aid in mold release and help processing. Both Epolene N-11P and N-14P are very low molecular weight polymers with average molecular weight values of 2000 and 1700 g/mol respectively. Additionally, these grades also have found use in NBR, SBR, and Butyl rubbers.
The C type products have proven to be very good process aids. Epolene C-10 has a higher molecular weight than Epolene N-34P. This higher molecular weight delivers a robustness to the final product and allows even higher mixing temperatures to be utilized. Epolene C-10 is used in EPDM as well as other non-polar and somewhat polar elastomers including NBR, SBR and Butyl rubbers. Typical loading levels of N and C type products in elastomeric compounds are 1.5-5.0 parts per hundred and can be used at levels as high as 10.0 parts in very demanding applications.
In addition to lubrication, many of the Epolene products when used in elastomeric systems allow for:
- ease of dispersion of fillers - improved flow properties
- reduced shrinkage - reduced tackiness during processing
- surface gloss
These products also find use in several different classes of thermoplastics including vinyls and olefins. Epolene E types, including E-14P, an oxidized low molecular weight polyethylene, and Epolene E-20, are used as internal lubricants. Furthermore, the E types typically are more compatible with PVC and aid internally as process aids. The N types, such as Epolene N-11 are less compatible and tend to aid externally as lubricants. In olefins, Epolene N-14 works very well as a mold release agent particularly for HDPE. Epolene E-43 is a chemically treated propylene based product. It performs favorably as a coupling agent for fillers in polypropylene. In addition, Epolene C-26 has been shown to help couple natural fibers in LDPE, HDPE and LLDPE.
We can provide a variety of process aids for your polymer systems, whether it is for elastomers or thermoplastics. Harwick Standard and Westlake Polymers stand ready to tackle your processing issues with solutions from the Epolene® line of products.