Question: We want to make polyurethane-type sealants for some construction applications but do not want to handle isocyanates. What are the alternatives?
Answer: The sealants you probably need are of two types. The first are based on polyether polyol backbones that are end-capped with alkoxy silane groups; the second are true polyurethane polymers, again with the alkoxy silane end groups. These polymers can react with moisture, liberate small amounts of alcohol, and crosslink similar to one-component RTV silicones. These sealants are sometimes called modified silicones polymers (MS), modified urethanes or hybrid sealants.