Melt extrudable polyvinyl alcohol compositions

Claim 1

A melt extrudable composition consisting essentially of (a) polyvinyl alcohol having a degree of polymerization from about 500 to about 2000 and a degree of hydrolysis of at least about 88%; (b) 0 to about 20% of plasticizer, based upon the weight of polyvinyl alcohol-plasticizer blend, selected from the group consisting of polyhydric alcohols of the formula R(OH) x where R is an alkyl group of C 2 -C 4 and x is 2-4 and ether condensation products thereof having a molecular weight of up to about 1000; aliphatic amides of the formula R'(CONR 2 R 3 ) x where R'=H or C 1 -C 6 alkyl, R 2 =H or C 1 -C 3 alkyl, R 3 =H or C 1 -C 3 alkyl and x=1-2, ureas of the formula R 4 R 6 NCONR 5 R 7 , where R 4 and R 6 =C 1 -C 3 alkyl and R 5 and R.sup. 7 =H or C 1 -C 3 alkyl, and hydroxylated aliphatic amines of the formula (R 8 ) 3 N, where R 8 is a mono- or dihydroxy alkyl group containing 2-4 carbon atoms and where the number of hydroxyl group is less than the number of carbon atoms; (c) about 0.5% to 5.0%, based upon the weight of polyvinyl alcohol-plasticizer blend, of a wax having a weight average molecular weight of from about 100 to about 4000, said wax being selected from the group consisting of fatty acids, fatty acid salts, fatty amides, fatty esters, fatty ethers, fatty alcohols and saturated and unsaturated hydrocarbons, provided that for blends of sodium acetate free polyvinyl alcohol neutral waxes are selected; (d) about 0.5% to 5.0%, based upon the weight of polyvinyl alcohol-plasticizer blend, of an ethylene polymer selected from the group consisting of homopolymers of ethylene and copolymers of ethylene with an ethylenically unsaturated monomer, said ethylene polymer having a weight average molecular weight of from about 4000 to about 50,000; provided that in any given blend the molecular weight of component (d) is at least three times higher than the molecular weight of component (c).