Abstract: A polyvinyl acetal/polyester graft copolymer obtained from a polyvinyl acetal having one or more of each of constituent units represented by the following general formulae (1) to (3) (wherein each of R1 and R2 represents a hydrogen atom, a linear or branched alkyl group having a carbon number of from 1 to 20, or an aryl group, in which the alkyl group or the aryl group may have a substituent) and having a weight average molecular weight of from 100 to 100,000 is used as a dispersant which prevents aggregation of solid particles in a dispersion liquid from occurring, is effective for forming a stable dispersion liquid, and exhibits excellent heat resistance.

Abstract: Paper with increased wet strength is produced by adding to the stock a water soluble blocked urethane prepolymer having a plurality of blocked isocyanate groups and hydrophilic groups. The blocking agent is a phenol compound having an electron-attracting group at the ortho- or para-position. The blocked urethane prepolymer is capable of unblocking under such conditions that encounter in the drying part of conventional paper making machines.

Abstract: Paper with increased wet strength is produced by adding to the stock a water soluble blocked urethane prepolymer having a plurality of blocked isocyanate groups and hydrophilic groups. The blocking agent is a phenol compound having an electron-attracting group at the ortho- or para-position. The blocked urethane prepolymer is capable of unblocking under such conditions that encounter in the drying part of conventional paper making machines.

Abstract: Radiation-curable polyurethane emulsion compositions that can be diluted with water are disclosed. An emulsion of a polyurethane having active amino groups is prepared, and the emulsion is reacted, in the presence of water, with an isocyanate compound having a polymerizable unsaturated group to introduce the polymerizable unsaturated group into the polyurethane. The introduction of a polymerizable unsaturated group into the polyurethane is accomplished in the presence of water, thereby overcoming prior art problems of polymerization and gelation during the preparation of the emulsion. The present invention provides radiation-curable polyurethane emulsion compositions that can be produced on an industrial scale.