Polymeric binders having specific peel and cure properties and useful in making creped webs
This invention is directed to alkylphenol ethoxylate (APE)-free polymer binders formed by aqueous free radical emulsion polymerization and having specific peel and cure properties. The APE-free polymeric binders have a peel value, when adhered to a heated metal surface, of 35% to 200% of the peel value shown by a standard APE-based polymer binder control and exhibit a cure profile such that at least 55% cure is achieved within 30 seconds at a temperature required for cure, and a wet tensile strength at 30-seconds of cure of at least 1000 g/5 cm. Wet tensile strength is used as a measure of cure. Binders having the peel and cure properties described herein can be considered for use in crepe processes, especially DRC processes.
1 . In a polymer binder used in a crepe process that comprises applying said polymer binder to a nonwoven web, drying, and creping the nonwoven web on a creping drum, the improvement which comprises an alkylphenol ethoxylate free aqueous polymer emulsion binder formed by aqueous free radical emulsion polymerization of one or more ethylenically unsaturated monomers and one or more crosslinking monomers, said binder having a peel value of 35% to 200% of a standard alkylphenol ethoxylate-based vinyl acetate-ethylene polymer emulsion control, a cure profile in which 55% cure is achieved within 30 seconds of being exposed to a temperature required for cure, and a wet tensile strength at 30-seconds of cure of at least 1000 g/5 cm.
2 . The polymer binder of claim 1 wherein the one or more crosslinking monomer is selected from the group consisting of an N-alkylol acrylamide, an N-alkylol methacrylamide, i-butyoxy methylacrylamide, acrylamidoglycolic acid, acrylamidobutyraldehyde, and a dialkyl acetal of acrylamidobutyraldehyde, wherein alkyl is 1 to 4 carbons.
3 . The polymer binder of claim 2 wherein the peel value is 50 to 125% of the polymer emulsion control.
4 . The polymer binder of claim 2 wherein the wet tensile strength at 30 seconds of cure is at least 1500 g/5 cm.
5 . In a polymer binder used in a double recrepe process wherein the recrepe process comprises applying said polymer binder to one side of a nonwoven web, drying, and creping the nonwoven web on a creping drum, followed by applying said polymer binder to the opposite side of the nonwoven web and again, drying, and creping the nonwoven web on a creping drum, the improvement which comprises an alkylphenol ethoxylate free aqueous polymer emulsion binder formed by aqueous free radical emulsion polymerization of one or more ethylenically unsaturated monomers and one or more crosslinking monomers, said binder having a peel value of 35% to 200% of a standard alkylphenol ethoxylate-based vinyl acetate-ethylene polymer emulsion control, a cure profile in which 55% cure is achieved within 30 seconds of being exposed to a temperature required for cure and a wet tensile strength at 30-seconds of cure of at least 1000 g/5 cm.
6 . The polymer binder of claim 5 wherein the one or more crosslinking monomer is selected from the group consisting of an N-alkylol acrylamide, an N-alkylol methacrylamide, i-butyoxy methylacrylamide, acrylamidoglycolic acid, acrylamidobutyraldehyde, and a dialkyl acetal of acrylamidobutyraldehyde, wherein alkyl is 1 to 4 carbons.
7 . The polymer binder of claim 5 having a viscosity of 5 to 80 cps at about 30% solids.
8 . The polymer binder of claim 5 wherein the peel value is 50 to 125% of the polymer emulsion control.
9 . The polymer binder of claim 5 wherein the wet tensile strength at 30 seconds of cure is at least 1500 g/5 cm.