| 摘要 |
A polyurethane coating, coating composition and coated substrate wherein the coating is essentially one macromolecule of homogeneous structure wherein the nitrogen atoms of the urethane groups are joined to alicyclic rings and/or straight aliphatic chains and the main polyurethane chains are crosslinked by three types of crosslinkages; via isocyanate residues and triol or tetrol residues, reactive upon curing by exposure to heat; via double bonds in vinyl compounds reactive, upon curing by exposure to radiation, with acrylo groups incorporated as acrylate esters into the polyurethane structures; and via urea groups formed by action of moisture upon isocyanate groups which are unreacted in the heat and radiation curing steps. On an equivalent weight basis, the ratio of all double bond crosslinkages: urethane crosslinkages is between 1.0 and 2.5; the content of urethane groups in the main polyurethane chains is from 40% up to no more than 70% of total equivalents of originally present isocyanate groups; the content of urethane crosslinkages on the same basis is 20-40%, and the content of urea groups on the same basis is about 5 to 25%. One particularly suitable substrate is resilient, foamed, embossed polyvinyl chloride yard goods such as used for floor covering.
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