| 摘要 |
<p>1376392 Polymer gel compositions DOW CHEMICAL CO 21 Jan 1972 [21 Jan 1971] 3047/72 Heading C3P [Also in Divisions A5 and E1] Compositions having increased adherence to cellulosic materials comprise a water-swellable, water-insoluble polymer gel in intimate mixture with from 1-100% by weight (based on the weight of dry gel) of a water-soluble cationic polymer. Preferred polymer gels are crosslinked polyacrylamides prepared by copolymerizing acrylamide with a crosslinking monomer containing two ethylenic double bonds, e.g. methylene-bis-acrylamide, in an aqueous medium and subsequently partially hydrolysing with alkali metal hydroxide to convert up to 50% of the carboxamide groups in the polymer to alkali metal carboxylate groups. Other useful polymer gels can be derived from crosslinked polyacrylate salts, crosslinked polymers and copolymers of vinyl oxazolidinone, vinylpyrrolidone, methacrylate salts or styrene sulphonate salts, and styrene-maleic anhydride copolymers crosslinked with a glycol. The cationic polymer may be a polyalkylene polyamine, a polyalkylenimine, or the product obtained by reacting a partially hydrolysed polyacrylamide with formaldehyde and dimethylamine to introduce dimethylaminomethyl substituents into the polymer. Exemplified polyamines or polyimines are polyethylenimine, polypropylenimine, polyethylene polyamine and polybutylene polyamine. The composition is preferably formed by adding an aqueous solution of the cationic polymer to the dry or partially water-swollen polymer gel, mixing mechanically and, for most purposes, drying the mixture to give a product in the form of fine granules or a powder. Products in which the polymer gel is swollen with water can be used in fire-fighting by being sprayed on or around the fire. In another embodiment the product can be applied to the surface of a cellulosic substrate for use as a water-absorbent article such as a bandage, pad or tissue; if the substrate is canvas or burlap the product can be used as a portable base for an ice rink, or as a roof covering for evaporative cooling of houses. Further applications of the treated cellulosic substrates are as a moisture barrier in porous soil and as a cover for retaining moisture on ski or sledding slopes.</p> |
