Loading patent…
AssigneeStockhausen GmbH & Co. KG
InventorMiroslav Chmelir
Estimating the term…
The present invention relates to cross-linked synthetic polymers based on acrylic acid and its derivatives, which have a high absorption capacity and an improved absorption rate for water, aqueous solutions and body fluids, to a process for their production by radical polymerization under such conditions that polymers are obtained which have a porous structure and a swelling degree-dependent particle density so that the polymer particles are floatable in water or aqueous liquids. The present invention further relates to the use of these polymers for the absorption and/or retention of water and for the release of water and/or an active substance solution to a surrounding medium. The porous structure of the polymers is formed by nitrogen dispersed in the polymer, with at least one azo compound being added to the aqueous monomer solution as polymerization initiator and blowing agent, which azo compound has a half-time of at least 10 hours at a temperature of 30.degree. to 120.degree. C.
A water-swellable, cross-linked, particulate polymer based on acrylic acid and its derivatives and having a porous structure, a high absorption capacity, and a high absorption rate for water and/or liquids, characterized in that the porous structure is formed by nitrogen dispersed in the polymer and that the polymer particles in dry condition have a density of above 1.0 g/cm.sup.3 and in swollen condition have a density of below 1.0 g/cm.sup.3 ;
A process for the production of a water-swellable, cross-linked, particulate polymer having a porous structure and a high absorption rate for water and/or aqueous liquids, comprising polymerizing or copolymerizing in aqueous solution a monomer selected from the group consisting of acrylic acid, methacrylic acid acrylamido methylpropane sulfonic acid, acrylamide and methacrylamide or copolymerizing said monomer with a water-soluble monomer and optionally a monomer only partially water-soluble or water-insoluble in amounts of up to 20%-wt., relative to the total monomer quantity, in the presence of at least one cross-linking di- or polyfunctional monomer, and optionally oligosaccharides and/or polysaccharides and/or polyvinyl alcohol, characterized in that the aqueous monomer solution comprises as polymerization initiator and blowing agent one or several azo compounds having a half-life of at least 10 hours at a temperature of 30.degree. to 120.degree. C., with the concentration of polymerization initiator and blowing agent, relative to the total monomer solution, amounting to 0.1 to 5.0%-wt., and that the polymer gel is crumbled, dried at 100.degree. to 240.degree. C., and ground.
Dependencies are inferred from the claim text.