COARSELY DISPERSED, SEDIMENTING AQUEOUS POLYURETHANE DISPERSIONS

摘要

Coarse, aqueous dispersions of polyurethanes that sediment but are capable of being redispersed are prepared from 40 to 99.5 percent by weight of a polyurethane polymer having a molecular weight greater than 5,000 and preferably above 20,000 which is free of salt-forming groups and from about 0.5 to about 60 percent by weight of a polyurethane polymer containing salt-forming groups. Salt formation is permitted to occur until 0,0007 to 0,011 equivalent percent has taken place and the mixture is then dispersed at least in a quantity of water such that the solids content is 60 percent.