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AssigneeAir Products and Chemicals, Inc.
InventorsLloyd M. Robeson, George Davidowich, Robert K. Pinschmidt, Jr.
Estimating the term…
The wet strength of cellulosic paper is improved by adding the combination of an amine-functional poly(vinyl alcohol) and a cellulose reactive size which is a 4 or 5 membered cyclic ester or anhydride having alkyl or alkenyl substituents of 4 or more carbon atoms. The amine-functional polymer is preferably a hydrolyzed copolymer of vinyl acetate and N-vinylformamide in which about 1-25 mole % of the monomer units are incorporated N-vinylformamide, and the cellulose reactive size is preferably an alkyl ketene dimer or an alkenyl succinic anhydride. A paper product is provided having improved wet-strength and containing normally 0.05 to 4.0 wt % based on the dry pulp of the additive amine-functional polymer and cellulose reactive size. The particular compounds which represent the polymer and the size cooperate to provide improvements in wet-tensile strength for paper which could not have been foreseen from the effects of either material acting alone.
A method of improving the wet-strength of cellulosic paper which comprises adding to the paper during the papermaking process an amine-functional poly(vinyl alcohol) copolymer having from 1 to 25 mole % amine functionality based upon incorporated monomer and a reactive sizing agent, which sizing agent comprises an alkyl ketene dimer or alkenyl succinic anhydride which have pendant substituents which contain a combined total of at least 8 carbon atoms, wherein said copolymer and reactive sizing agent are added to the paper in a combined concentration of from about 0.05 to 4 wt % based upon the dry paper pulp, and the weight ratio of the copolymer to the sizing agent is from 1:10 to 10:1.
A cellulosic paper product having improved wet-strength containing products formed by addition to the paper during manufacture of from about 0.05 to 4 wt %, based upon dry paper pulp, of the combination of an amine-functional poly(vinyl alcohol) copolymer having from 1 to 25 mole % amine functionality based upon incorporated monomer and a cellulose reactive size which is a 4 or 5 membered cyclic ester or anhydride having one or more alkyl or alkenyl substituents which substituents contain a combined total of at least 8 carbon atoms , which copolymer and reactive size are added in a weight ratio from 1:10 to 10:1.
Dependencies are inferred from the claim text.