Priming agent for separating papers and films
Release papers and films are coated with a primer containing a silane-modified polyvinyl alcohol and an H-siloxane prior to coating with an abhesive silicone release coating.
1 - 12 . (canceled)
13 . A primer composition for release papers and release films, comprising
a) at least one silane-containing polyvinyl alcohol comprising fully or partly hydrolyzed vinyl ester copolymers having a degree of hydrolysis of 75 to 100 mol %, obtained by free-radically polymerizing
a)i) one or more vinyl esters of unbranched or branched alkylcarboxylic acids having 1 to 18 carbon atoms, of which a fraction of 1 to 30 mol %, based on total polymer, comprise one or more 1-alkylvinyl esters of carboxylic acids having 1 to 6 carbon atoms, the alkyl radicals of the 1-alkylvinyl esters having 1 to 6 carbon atoms,
a)ii) 0.01 to 10 mol % of one or more silane-containing, ethylenically unsaturated monomers, and optionally,
a)iii) further comonomers copolymerizable therewith, and hydrolyzing the resultant polymers, and
b) at least one reactive H-siloxane.
14 . The primer of claim 13 , wherein the silane-containing polyvinyl alcohol is obtained by hydrolyzing a vinyl acetate copolymer.
15 . The primer of claim 13 , wherein one or more 1-alkylvinyl esters selected from the group consisting of 1-methylvinyl acetate, 1-ethylvinyl acetate, and 1-propylvinyl acetate are copolymerized.
16 . The primer of claim 13 , wherein the silane-containing polyvinyl alcohol is obtained by copolymerizing one or more ethylenically unsaturated, silane-containing monomers selected from the group consisting of ethylenically unsaturated silicon compounds of the formula (I) R 1 SiR 2 0-2 (OR 3 ) 1-3 , where R 1 is CH 2 ═CR 4 —(CH 2 ) 0-3 or CH 2 ═CR 4 CO 2 (CH 2 ) 1-3 , R 2 is a C 1 to C 3 alkyl radical, C 1 to C 3 alkoxy radical, or halogen, R 3 is an unbranched or branched, unsubstituted or substituted alkyl radical having 1 to 12 carbon atoms, or an acyl radical having 2 to 12 carbon atoms, R 3 optionally being interrupted by an ether group, and R 4 is H or CH 3 , and
meth(acrylamides) containing silane groups, of the formula (II) CH 2 ═CR 5 —CO—NR 6 —R 7 —SiR 8 m —(R 9 ) 3-m , where m=0 to 2, R 5 is H or a methyl group, R 6 is H or an alkyl group having 1 to 5 carbon atoms; R 7 is an alkylene group having 1 to 5 carbon atoms or a divalent organic group in which the carbon chain is interrupted by an oxygen or nitrogen atom, R 8 is an alkyl group having 1 to 5 carbon atoms, R 9 is an alkoxy group having 1 to 40 carbon atoms, which may be substituted by further heteroatoms.
17 . The primer of claim 16 , wherein the silane-containing polyvinyl alcohol is obtained by copolymerizing one or more ethylenically unsaturated, silane-containing monomers selected from the group consisting of γ-acryloyloxy- and γ-methacryloyloxypropyltri(alkoxy)silanes, α-meth-acryloyloxymethyltri(alkoxy)silanes, γ-methacryl-oyloxypropylmethyldi(alkoxy)silanes, vinylalkyldi-(alkoxy)silanes and vinyltri(alkoxy)silanes.
18 . The primer of claim 17 , wherein the alkoxy group(s) are selected from the group consisting of methoxy, ethoxy, methoxyethylene, ethoxyethylene, methoxypropylene glycol ether and ethoxypropylene glycol ether radicals.
19 . The primer of claim 13 , wherein 0.01 to 2.0 mol % of ethylenically unsaturated, silane-containing monomers are copolymerized.
20 . The primer of claim 13 , wherein at least one reactive silicone component b) is selected from the group consisting of linear, cyclic or branched organopolysiloxanes comprising units of the formula (III) R e H f SiO (4-e-f)/2 , where e is 0, 1, 2 or 3, f is 0, 1 or 2, and the sum of e+f is ≦3, with the proviso that there are on average at least 2 Si-bonded hydrogen atoms, and R is a monovalent, SiC-bonded, unsubstituted or substituted hydrocarbon radical having 1 to 18 carbon atoms.
21 . The primer of claim 20 , wherein at least one reactive silicone component b) is selected from the group consisting of organopolysiloxanes of the formula (IV) H h R 3-h SiO(SiR 2 O) o (SiRHO) p SiR 3-h H h , where h is 0, 1 or 2, o is 0 or an integer from 1 to 1500, and p is 0 or an integer from 1 to 200, with the proviso that the organopolysiloxanes of the formula (IV) contain on average at least 2 Si-bonded hydrogen atoms.
22 . The primer of claim 13 , wherein the ratio of the silane-containing polyvinyl alcohol component (a) to the silicone component (b) (solids/solids) is from 99:1 to 1:99.
23 . In a process for the silicone coating of a paper or film substrate to form a release coating wherein a primer is used, the improvement comprising coating the substrate with a primer of claim 13 prior to coating with a silicone abhesive coating.
24 . A release paper or film, prepared by the process of claim 23 .
25 . A release film or paper comprising
a) a substrate comprising at least one of a film or a paper;
b) coated onto said substrate a primer of claim 13;
c) coated onto said primer a silicone abhesive coating.