Impact Modifiers for Vinyl Siding

May 06, 2004 2 Replies

Was hoping someone could help me. We typically like acrylics due to their excellent impact properties. Sharp jumps in PVC resin cost are now forcing us to consider reformulation. I'm trying to understand:


- What are the alternative(s) to acrylics (if there are any)?



- Usage level of alternative(s) (pph)



- cost/lb of alternative(s)?



Would appreciate any help with this.



Thank you B. Polimera


There are two basic alternatives to acrylic impact modifiers, methacrylate-butadiene-styrene (MBS) and chlorinated polyethylene (CPE). Both are typically cheaper than acrylics and since they affect the fusion characteristics of the formulation, neither is a drop in. If you are making a weatherable product such as siding or window or door lineals, you should rule MBS out. The double bond in the butadiene phase readily reacts with UV and yellows the formulation. CPE can and is used in weatherable applications. Normally you can substitute one for one with your acrylic modifier. CPE modified formulation often fuse slightly slower than acrylic modified ones. So, you may have to adjust your lubricant package slightly to bring back your fusion rate. One advantage to CPE modified formulation is that since it is an uncrosslinked elastomer it tends to coat the filler and pigment particles. This allows you to use more filler (CaCO3) than in acrylic modified formulations. The largest CPE supplier in North American and Europe is DuPont Dow Elastomers. The brand name for their product is Tyrin. You can find more information on their website:

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Larry - Thank you for the information and your insights.

B. Polimera

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