Binders curable at room temperature with low blocking
View Patent ↗Topically-applied binder materials for imparting wet strength to soft, absorbent paper sheets, such as are useful as household paper towels and the like, include an azetidinium-reactive polymer, such as a carboxyl-functional polymer, an azetidinium-functional polymer and, optionally, a component useful for reducing sheet-to-sheet adhesion (blocking) in the product. These binder materials can be cured at ambient temperature over a period of days and do not impart objectionable odor to final product when wetted.
1. A method of increasing the strength of a paper towel basesheet comprising topically applying an aqueous binder composition to one or both outer surfaces of the web to produce a fibrous web having at least one binder-treated surface, wherein the binder composition comprises a mixture of an azetidinium-reactive polymer, an azetidinium-functional cross-linking polymer and from about 1 to about 25 weight percent, on a solids basis relative to the amount of the azetidinium-reactive polymer, of an anti-blocking additive, and thereafter adhering a binder-treated surface of the fibrous web to a creping cylinder and creping the web, wherein the anti-blocking additive is selected from the group consisting of glyoxal, gluteraldehyde, waxes and sugars.
2. The method of claim 1 wherein the aqueous binder composition is applied to both outer surfaces of the fibrous web and both sides of the web are adhered to a creping cylinder and creped.
3. The method of claim 1 or 2 wherein the aqueous binder composition is cured at a temperature of 120° C. or less.
4. The method of claim 1 or 2 wherein the aqueous binder composition is cured at a temperature of 100° C. or less.
5. The method of claim 1 or 2 wherein the aqueous binder composition is cured at a temperature of 40° C. or less.
6. The method of claim 1 or 2 wherein the aqueous binder composition is cured at a temperature of from about 20 to about 120° C.
7. The method of claim 1 or 2 wherein the amount of the anti-blocking additive is from about 5 to about 20 weight percent.
8. The method of claim 1 or 2 wherein the amount of the anti-blocking additive is from about 10 to about 15 weight percent.
9. The method of claim 1 or 2 wherein the anti-blocking additive is glyoxal.
10. The method of claim 1 or 2 wherein the anti-blocking additive is glutaraldehyde.
11. The method of claim 1 or 2 wherein the anti-blocking additive is a non-reactive additive selected from the group consisting of, and oils waxes and oils.
12. The method of claim 1 or 2 wherein the anti-blocking additive is a soluble or insoluble crystal selected from the group consisting of sugars.