Incorporation of a self-crosslinking polymer into a nonwoven binder for use in improving the wet strength of pre-moistened wipes
This invention is directed to an aqueous polymeric binder composition that is useful in improving the wet strength of pre-moistened wipes. The binder composition comprises a blend or mixture of two components. One component is a water dispersible polymer capable of binding together the fibers composing a nonwoven web. The other component is an aqueous solution or dispersion of a polymer comprised predominantly of self-crosslinking monomer(s).
1. A packaged pre-moistened wet wipe comprising,
1) a web of nonwoven fibers bonded with a binder;
2) the binder comprises a blend of:
a) a water dispersible polymeric binder; and
b) an aqueous solution or an aqueous dispersion of a polymer comprising predominantly self-crosslinking monomer;
3) the total amount of crosslinking monomer in the blend is 1 to 11 wt. %, based on the total weight of solids.
2. The packaged pre-moistened wet wipe of claim 1 wherein the blend comprises 90 to 99 wt % of the water dispersible polymeric binder and 1 to 10 wt % of the polymer comprising predominantly seif-crosslinking monomer, based on the total weight of solids.
3. The packaged pre-moistened wet wipe of claim 1 wherein the blend comprises 95 to 97 wt % of the water dispersible polymeric binder and 3 to 5 wt % of the polymer comprising predominantly self -crosslinking monomer, based on the total weight of solids.
4. The packaged pre-moistened wet wipe of claim 1 wherein the water dispersible polymeric binder is a polymer emulsion, said polymer emulsion comprises a polymer containing 50 to 95 wt % of a vinyl ester 5 to 30 wt % of another ethylenically unsaturated monomer, 0 to 8 wt % of a self-crosslinking monomer, and 0 to 10 wt % of a functional monomer.
5. The packaged pre-moistened wet wipe of claim 4 wherein said polymer emulsion comprises a polymer containing 65 to 85 wt % of a vinyl ester 7 to 20 wt % of another ethylenically unsaturated monomer, 1 to 5 wt % of a self-crosslinking monomer, and 2 to 10 wt % of a functional monomer.
6. The packaged pre-moistened wet wipe of claim 5 wherein the vinyl ester is vinyl acetate, the other ethylenically unsaturated monomer is selected from the group consisting of ethylene, butyl acrylate, vinyl versatate, or mixtures thereof, the self-crosslinking monomer is selected from the group consisting of N-methylol acrylamide, acrylamide, i-butoxy methylacrylamide, acrylamidoglycolic acid, acrylamidobutyraldehyde, a dialkyl acetal of acrylamidobutyraldehyde, and mixtures thereof, the functional monomer is selected from the group consisting of acetoacetoxyethyl methacrylate (AAEM), hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxybutyl acrylate, and mixtures thereof.
7. The packaged pre-moistened wet wipe of claim 6 wherein the polymer comprising predominantly self-crosslinking monomer comprises 50 to 100 wt % monomers, based on total solids, selected from the group consisting of N-methylol acrylamide, acrylamide, isobutyl methacrylamide, n-butyl methacrylamide; acrylamidoglycolic acid, acryamidobutyraldehyde dialkyl acetal, and mixtures thereof, wherein each alkyl contains 1 to 4 carbons.
8. The packaged pre-moistened wet wipe of claim 7 wherein the polymer comprising predominantly self-crosslinking monomer further comprises monomers selected from the group consisting of vinyl acetate, butyl acrylate, methyl methacrylate, and vinyl versatate.
9. The packaged pre-moistened wet wipe of claim 1 wherein the polymeric binder and the polymer comprising predominantly self-crosslinking monomer are in an aqueous emulsion.
10. The packaged pre-moistened wet wipe of claim 1 wherein the binder is free of alkylphenol ethoxylates.
11. A packaged pre-moistened wet wipe comprising,
1) a web of nonwoven fibers bonded with a binder;
2) the binder comprises a blend of:
a) a water dispersible polymeric binder; and
b) an aqueous solution or an aqueous dispersion of a polymer comprising predominantly seif-crosslinking monomer;
3) the total amount of crosslinking monomer in the blend is 1 to 11 wt. %, based on the total weight of solids; and the water dispersible polymeric binder is a polymer emulsion comprising a polymer containing 65 to 85 wt. % vinyl acetate, 7 to 20 wt. % ethylene, 1 to 5 wt. % N-methylol acrylamide, and 2 to 10 wt. % acetoacetoxyethyl methacrylate.