Crosslinkable stabilized composition for a nonwoven substrate and process for preparing the same

Abstract

A crosslinkable stabilized composition for a nonwoven substrate includes an aqueous dispersion of vinyl acetate-ethylene copolymers, a polyvinyl alcohol dispersion stabilizer, and a copolymer comprising maleic anhydride units or a copolymer comprising maleic acid units. The composition exhibits a free formaldehyde content of 5 ppm or less.

1 . A crosslinkable stabilized composition for a nonwoven substrate, comprising:
 an aqueous dispersion of vinyl acetate-ethylene copolymers, a polyvinyl alcohol dispersion stabilizer, and a copolymer comprising maleic anhydride units or a copolymer comprising maleic acid units, wherein the composition exhibits a free formaldehyde content of 5 ppm or less.   
     
     
         2 . The crosslinkable stabilized composition of  claim 1 , wherein the composition exhibits a viscosity of 4000 mPa-s or less when measured at 23° C. and using a no. LV-3 spindle at 60 revolutions per minute. 
     
     
         3 . The crosslinkable stabilized composition of  claim 1 , wherein the copolymer further comprises ethylene units. 
     
     
         4 . The crosslinkable stabilized composition of  claim 1 , wherein the composition does not comprise N-methylol acrylamide. 
     
     
         5 . The crosslinkable stabilized composition of  claim 1 , wherein composition comprises the copolymer in an amount of 0.5 wt % or more based on the total weight of monomers in the aqueous dispersion. 
     
     
         6 . The crosslinkable stabilized composition of  claim 1 , wherein the polyvinyl alcohol dispersion stabilizer comprises a partially hydrolysed polyvinyl acetate having an average degree of hydrolysis of 80 to 96 mol %. 
     
     
         7 . The crosslinkable stabilized composition of  claim 2 , wherein the composition exhibits a viscosity of 200 to 4000 mPa-s when measured at 23° C. and using a no. LV-3 spindle at 60 revolutions per minute. 
     
     
         8 . The crosslinkable stabilized composition of  claim 2 , wherein the viscosity exhibited by the composition does not undergo a change of more than 60% after 75 days at 20° C. 
     
     
         9 . The crosslinkable stabilized composition of  claim 3 , wherein the copolymer comprises ethylene maleic anhydride polymers. 
     
     
         10 . The crosslinkable stabilized composition of  claim 8 , wherein the viscosity exhibited by the composition does not undergo a change of more than 25% after 75 days at 20° C. 
     
     
         11 . Process for preparing a crosslinkable stabilized composition for a nonwoven substrate, comprising:
 providing a copolymer comprising maleic anhydride units or a copolymer comprising maleic acid units;   providing vinyl acetate and ethylene;   polymerizing vinyl acetate and ethylene in the presence of a polyvinyl alcohol dispersion stabilizer to form vinyl acetate-ethylene copolymers; and   forming a composition comprising the vinyl acetate-ethylene copolymers and that has a formaldehyde level of 5 ppm or less.   
     
     
         12 . The process of  claim 11 , wherein the vinyl acetate-ethylene copolymers are provided in an aqueous dispersion that is formed by emulsion polymerization. 
     
     
         13 . The process of  claim 11 , wherein the copolymer is mixed with the polyvinyl alcohol dispersion stabilizer prior to forming the vinyl acetate-ethylene copolymers. 
     
     
         14 . The process of  claim 11 , wherein the copolymer is provided in an amount of 0.5 wt % or more based on total weight of monomers in the aqueous dispersion. 
     
     
         15 . The process of  claim 11 , wherein the composition exhibits a viscosity of 50 to 4000 mPa-s when measured at 23° C. and using a no. LV-3 spindle at 60 revolutions per minute. 
     
     
         16 . The process of  claim 11 , wherein the copolymer further comprises ethylene units. 
     
     
         17 . The process of  claim 12 , further comprising mixing the copolymer with the aqueous dispersion to form the composition. 
     
     
         18 . The process of  claim 14 , wherein the copolymer is provided in an amount of 0.5 to 5 wt % based on total weight of monomers in the aqueous dispersion. 
     
     
         19 . A nonwoven product, comprising:
 a nonwoven substrate treated with the composition of  claim 1 , wherein the nonwoven product exhibits a wet tensile strength that is 25% or more of a dry tensile strength exhibited and a formaldehyde content of 1.5 ppm or less.   
     
     
         20 . The nonwoven product of  claim 19 , wherein the copolymer and vinyl acetate-ethylene copolymers are crosslinked.