| 摘要 |
Water-swellable, compact or cellular materials (I), esp. sealing materials, are produced by incorporating water-absorbent cpds. (II) in a matrix (III) which is obtd. by reaction of known hydrophilic NCO-prepolymers (IV) with known chain-extenders (V) to give polyureas. The reaction mixt. pref. contains dissolved, emulsified or dispersed resins, oils or polymers as reinforcing and/or extending materials and/or to increase the solids content and reduce shrinkage; (II) are clay minerals, e.g. smectite, bentonite or montmorillonite, or cellulose ethers, polysaccharides or alginates, or lightly crosslinked polymeric OH cpds., salts or amides of propenoic acids, pref. obtd. by in situ polymerisation during or after prodn. of (I) by polymerisation, pref. in the presence of polyfunctional comonomers which reduce the water solubility of the polymer by crosslinking, using catalysts which are initiated by means of a redox catalyst in the mixt. or by subsequent heating or irradiation. USE/ADVANTAGE - Provides a material for sealing cracks and joints in building work etc., which swells rapidly on contact with water to give a mechanically strong, very elastic seal with very good resistance to chemicals and environmental effects.
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