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AssigneeNational Starch and Chemical Corporation
InventorsDaniel B. Solarek, Patrick G. Jobe, Martin M. Tessler
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Polysaccharide aldehydes having the general structure ##STR1## such as starch, cellulose and gum aldehydes, are useful for imparting wet, dry, or temporary wet strength to paper. They are prepared by a non-oxidative method which involves reacting the polysaccharide base, in the presence of alkali, with a derivatizing acetal reagent having the general structure ##STR2## and then hydrolyzing the acetal by adjusting the pH to less than 7, preferably 2-4. R is (CH.sub.2).sub.n or a divalent aromatic group and n os 0 or greater; R.sup.1, R.sup.6, and R.sup.7 are hydrogen or an organic group; R.sup.2, R.sup.5, and R.sup.8 are (CH.sub.2).sub.m with m being 1-6; R.sup.3 and R.sup.4 are hydrogen or a lower alkyl; Y is an anion; Z is an organic group capable of reacting with the polysaccharide base to form an ether derivative and selected from the group consisting of an epoxide, ethylenically unsaturated group, halohydrin, and halogen; R.sup.11, if present, is a divalent organic group containing no reactive substiuents; and A and A' are lower alkyls or together form at least a 5-membered cyclic acetal.
In a method for making paper having dry strength, wet strength, temporary wet strength, or combinations thereof, the step which comprises adding, as a strength aid, to the stock at any stage prior to forming a web, an effective amount of an aldehyde-containing polysaccharide having the general structure ##STR70## wherein Sacch--O-- represents a polysaccharide molecule;
A paper containing, as a strength aid, an effective amount of an aldehyde-containing polysaccharide having the general structure ##STR71## wherein Sacch--O-- represents a a polysaccharide molecule;
Dependencies are inferred from the claim text.