Polymer obtainable by a multistage polymerization process which involves conducting, in a first step, an aqueous-phase polymerization of at least one ethylenically monofunctional compound alone or together with at least one ethylenically difunctional or poly-functional compound together in the presence of a polyesterpolyol, polyurethane and/or polyacrylate; and, in a subsequent step, a reaction of the resulting product with at least one ethylenically monofunctional compound alone or together with at least one ethylenically difunctional or polyfunctional compound; followed by a reaction of the resulting product with a crosslinker; and its use.
A crosslinking agent containing a polyallyl ether compound having at least one hydroxyl group derived from a glycidyl group and at least two allyl groups can be used for the production of a highly water-absorbing polymer comprising a polymerizable compound having a carbon-carbon double bond or a salt thereof, has a high solubility in aqueous solution of the monomer and gives a highly water-absorbing polymer having water absorptivity required at practical levels.
