| 摘要 |
Adhesive compositions comprise (a) a polyvalent metal oxide or hydroxide or a clay containing a polyvalent metal oxide or hydroxide and (b) either (i) a polyvinyl alcohol derivative containing 5 to 70 mole per cent of carboxyl groups or (ii) a mixture of polyvinyl alcohol and a macromolecular substance containing 5 to 70 mole per cent of carboxyl groups. The oxides or hydroxides may be of calcium, magnesium, zinc, lead, copper, aluminium or iron. Specified polyvinyl alcohol derivatives (i) are saponified copolymers of vinyl acetate with acrylic esters, methacrylic esters, acrylamide or acrylonitrile, and polyvinyl alcohol etherified with glycolic acid or acetalized with glyoxylic acid. Specified high molecular weight substances containing carboxyl groups are polyacrylic acid or saponified polyacrylamide or polyacrylonitrile. Examples describe aqueous adhesive compositions comprising polyvinyl alcohol and polyacrylic acid together with (1) zinc oxide and (2 and 4) calcium oxide; and comprising polyvinyl alcohol etherified with glycolic acid and (3) clay.ALSO:Substrates may be coated with compositions comprising as water-resistant binder (a) a polyvalent metal oxide or hydroxide or a clay containing such an oxide or hydroxide and (b) either (i) a polyvinyl alcohol derivative containing 5 to 70 mole per cent of carboxyl groups or (ii) a mixture of polyvinyl alcohol and a macro molecular substance containing 5 to 70 mole per cent of carboxyl groups. Specified oxides and hydroxides are of calcium, magnesium, zinc, lead, copper, aluminium and iron, and (b) may be saponified copolymers of vinyl acetate with acrylic or methacrylic esters, acrylamide or acrylonitrile, or a mixture of polyvinyl alcohol with polyacrylic acid or saponified polyacrylamide or polyacrylonitrile. In examples (1) polyvinyl chloride sheet is coated with an aqueous composition comprising polyvinyl alcohol, polyacrylic acid and zinc oxide and (3) paper is coated with an aqueous composition comprising polyvinyl alcohol partially etherified by glycolic acid and clay. |
