Provided is a two-component polyurethane composition, comprising, (a) an isocyanate component that comprises: at least one aromatic isocyanate compound, and (b) a polyol component that comprises: at least one polyether polyol compound, a sulfide-free urea or a derivative thereof, an alcohol chain extender, wherein the isocyanate component and polyol component have an NCO/OH ratio of from 0.9:1 to 1.2:1. Also provided are a product prepared using the polyurethane composition, and the preparation method thereof.

In some aspects, the present disclosure provides systems for forming hydrogels that comprise (i) a reactive multi-arm polymer that comprises three or more polymer arms linked to a core region, each arm comprising a polyether segment and a reactive moiety comprising a cyclic imide carboxy-C.sub.1-C.sub.6-alkyl ester end group or each arm comprising a polyether segment and a reactive moiety comprising a C.sub.2-C.sub.6-isocyanoalkyl end group and (ii) a polyamino compound comprising at least two amino (NH.sub.2) groups, wherein the reactive multi-arm polymer and the polyamino compound react to form a crosslinked hydrogel that does not contain ester groups and has long-term stability in vivo. In some aspects, the present disclosure provides methods of treatment using such systems and hydrolysis-resistant crosslinked hydrogels formed from such systems.

A two-component mixed polyurea resin composition production raw material containing a component (A) that contains a polyisocyanate compound (a) and a component (B) that contains an aromatic polyamine compound (b), wherein the two-component mixed polyurea resin composition production raw material is characterized in that the usable time from immediately after component (A) and component (B) are mixed until the viscosity value measured in an organic-solvent-free state doubles is 10 minutes or longer.

The invention relates to an aqueous resin dispersion comprising a mixture of a hydrophilically modified epoxy-based resin, a crosslinker, and a co-crosslinker. The present invention also relates to an aqueous coating composition, comprising said resin dispersion, providing improved corrosion and discolouration resistance; to a process for the preparation of the aqueous resin dispersion and the coating composition; and to the use of the coating composition for coating metal substrates.