Alkylphenol ethoxylate-free surfactant package for polymer emulsions
This invention is directed to formation of a creped nonwoven web. The creped web is formed in a creping process using a polymer emulsion binder formed in an alkylphenol ethoxylate-free surfactant system. The surfactant system comprises a combination of a specific active anionic surfactant (sodium laureth sulfate containing 1 to 12 moles of ethylene oxide) and a specific active nonionic surfactant (a secondary alcohol ethoxylate containing 7 to 30 moles of ethylene oxide or an ethoxylated branched primary alcohol containing 3 to 30 moles of ethylene oxide.)
1. In a method for forming a bonded and creped nonwoven web which comprises: applying a polymer emulsion binder to a nonwoven web to form a coated nonwoven web, drying the coated nonwoven web, and subsequently creping said dried coated nonwoven web in a crepe process, the improvement which comprises using an alkylphenol ethoxylate-free polymer emulsion binder formed by polymerizing vinyl acetate, ethylene, and one or more crosslinking monomers, under emulsion polymerization conditions, in the presence of a combination of an anionic surfactant and a nonionic surfactant, wherein said anionic surfactant is a sodium laureth sulfate having 1 to 12 moles of ethylene oxide, said nonionic surfactant is a secondary alcohol ethoxylate containing 7 to 30 moles of ethylene oxide or an ethoxylated branched primary alcohol containing 3 to 30 moles of ethylene oxide, said primary or secondary alcohol containing 7 to 18 carbons.
2. The method of claim 1 wherein the one or more crosslinking monomers is selected from the group consisting of a N-(C 1-4 ) alkylol (meth)acrylamide, i-butoxy methylacrylamide, acrylamidoglycolic acid, acrylamidobutyraldehyde, a dialkyl acetal of acrylamidobutyraldehyde, said alkyl having 1 to 4 carbons, and acrylamide in combination with one or more of the aforementioned crosslinking monomers.
3. The method of claim 1 wherein the crosslinking monomer is N-methylol acrylamide.
4. The method of claim 1 wherein the polymer emulsion comprises 50 to 90 wt % vinyl acetate, 5 to 49 wt % ethylene, and 1 to 10 wt % of N-methylol acrylamide, based on the total weight of monomers.
5. The method of claim 1 wherein the polymer emulsion comprises 70 to 85 wt % vinyl acetate, 10 to 30 wt % ethylene, and 3 to 8 wt % of N-methylol acrylamide, based on the total weight of monomers.
6. The method of claim 1 wherein said anionic surfactant is a sodium laureth sulfate containing 2 to 5 moles of ethylene oxide and said nonionic surfactant is a secondary alcohol ethoxylate having 12 to 20 moles of ethylene oxide or an ethoxylated branched primary alcohol containing 9 to 20 moles of ethylene oxide, and the weight ratio of anionic to nonionic surfactant ranges from 4:1 to 1.5:1.
7. The method of claim 1 wherein said anionic surfactant is a sodium laureth sulfate containing 4 moles of ethylene oxide and said nonionic surfactant is a secondary alcohol ethoxylate having 20 moles of ethylene oxide.
8. The method of claim 7 wherein said nonionic surfactant is tridecanol ethoxylate containing 9 to 20 moles of ethylene oxide.
9. The method of claim 1 wherein the weight ratio of anionic surfactant to nonionic surfactant is 65:35.
10. The method of claim 1 wherein the crepe process is a double recrepe process.
11. The method of claim 10 wherein the one or more crosslinking monomers is selected from the group consisting of a N-(C 1-4 ) alkylol (meth)acrylamide, i-butoxy methylacrylamide, acrylamidoglycolic acid, acrylamidobutyraldehyde, a dialkyl acetal of acrylamidobutyraldehyde, said alkyl having 1 to 4 carbons, and acrylamide in combination with one or more of the aforementioned crosslinking monomers.
12. The method of claim 10 wherein the crosslinking monomer is N-methylol acrylamide.
13. The method of claim 10 wherein the polymer emulsion comprises 50 to 90 wt % vinyl acetate, 5 to 49 wt % ethylene, and 1 to 10 wt % of N-methylol acrylamide, based on the total weight of monomers.
14. The method of claim 10 wherein the polymer emulsion comprises 70 to 85 wt % vinyl acetate, 10 to 30 wt % ethylene, and 3 to 8 wt % of N-methylol acrylamide, based on the total weight of monomers.
15. The method of claim 10 wherein said anionic surfactant is a sodium laureth sulfate containing 2 to 5 moles of ethylene oxide and said nonionic surfactant is a secondary alcohol ethoxylate having 12 to 20 moles of ethylene oxide or an ethoxylated branched primary alcohol containing 9 to 20 moles of ethylene oxide, and the weight ratio of anionic to nonionic surfactant ranges from 4:1 to 1.5:1.
16. The method of claim 10 wherein said anionic surfactant is a sodium laureth sulfate containing 4 moles of ethylene oxide and said nonionic surfactant is a secondary alcohol ethoxylate having 20 moles of ethylene oxide.
17. The method of claim 16 wherein said nonionic surfactant is tridecanol ethoxylate containing 9 to 20 moles of ethylene oxide.
18. The method of claim 10 wherein the weight ratio of anionic surfactant to nonionic surfactant is 65:35.