| 摘要 |
<p>The invention relates to the use of (meth)acrylic acid amide(s) as comonomer(s) (b) for providing improved heat resistance by a formaldehyde-free aqueous polymer dispersion obtained by emulsion copolymerization of at least
(a) vinyl ester monomer(s) and
(b) comonomer(s) comprising said acrylic and/or methacrylic amide(s) derivatives in the presence of at least
(c) fully hydrolyzed polyvinyl alcohol (PVOH), having an average degree of hydrolysis above 95.00 mol%,
wherein the polymerization does not comprise comonomers derived from N-alkylol(meth)acrylic acid amides,
and wherein the heat resistance, measured as WATT 91 value according to DIN EN 14257, is larger than the heat resistance obtained without using acrylic and/or methacrylic amide(s) derivatives (b). The invention further relates to formaldehyde-free aqueous polymer dispersions obtainable by emulsion copolymerization of vinyl ester monomer(s) (a) in the presence of fully hydrolyzed polyvinyl alcohol (PVOH) (c), using comonomer(s) (b), the comonomer(s) (b) comprising (meth)acrylic acid amide(s) for obtaining a formaldehyde-free aqueous polymer dispersion providing improved heat resistance, measured as WATT 91 value according to DIN EN 14257 according to any one of claims 1 to 10, comprising
2 to less than 12 wt.%, based on total used monomer, of fully hydrolyzed polyvinyl alcohol (PVOH) (c),
wherein the fully hydrolyzed PVOH has an average degree of hydrolysis above 98.00 mol% up to 99.95 mol%,
wherein the polymerization does not comprise comonomers derived from N-alkylol(meth)acrylic acid amides,
wherein the polymerization does not involve partially hydrolyzed PVOH having an average degree of hydrolysis up to 95 mol%,
the polymer dispersion providing
- a water resistance, measured as D3/3 value of a wood bond according to DIN EN 204/205 of D3/3 of at least 1.5 N/mm 2 ,
- a heat resistance measured as WATT 91 value of a wood bond according to DIN EN 14257 of at least 6 N/mm 2 and a process for providing such aqueous polymer dispersions.</p> |
