Compositions in the Form of Dissolvable Solid Structures

Abstract

Described are dissolvable, porous solid structures formed using certain vinyl acetate-vinyl alcohol copolymers. The copolymer and the porosity of the structure allow for liquid flow during use such that the structure readily dissolves to provide a desired consumer experience. Also described are processes for making open cell foam and fibrous dissolvable solid structures.

What is claimed is: 
     
         1 . A Structure in the form of a porous dissolvable solid, comprising:
 (a) from about 1 wt % to about 95 wt % surfactant; and   (b) from about 5 wt % to about 50 wt % of a copolymer comprising vinyl acetate and vinyl alcohol units, wherein the copolymer comprises not more than about 84% alcohol units.   
     
     
         2 . The Structure of  claim 1  wherein the copolymer comprises not more than about 82.5% alcohol units. 
     
     
         3 . The Structure of  claim 1  wherein the copolymer comprises not more than about 81% alcohol units. 
     
     
         4 . The Structure of  claim 1  wherein the copolymer comprises from about 70% to about 81% alcohol units. 
     
     
         5 . The Structure of  claim 4  wherein the copolymer has a weight average molecular weight (M W ) of from about 20,000 to about 500,000. 
     
     
         6 . The Structure of  claim 1  comprising at least one additional copolymer comprising vinyl acetate and vinyl alcohol units, wherein the at least one additional copolymer comprises not more than about 84% alcohol units and has a weight average molecular weight of from about 60,000 to about 300,000. 
     
     
         7 . The Structure of  claim 1  further comprising from about 1 wt % to about 25 wt % plasticizer. 
     
     
         8 . The Structure of  claim 1  having a porosity of from about 25% to about 99%. 
     
     
         9 . The Structure of  claim 8  having a porosity of from about 50% to about 98%. 
     
     
         10 . The Structure of  claim 1  comprising from about 5 wt % to about 65 wt % surfactant. 
     
     
         11 . The Structure of  claim 1  in the form of an open celled foam with a percent open cell content of from about 70% to about 100% wherein the foam Structure further comprises from about 1 wt % to about 25 wt % plasticizer. 
     
     
         12 . The Structure of  claim 11  wherein the copolymer comprises from about 65% to about 82.5% alcohol units. 
     
     
         13 . The Structure of  claim 12  wherein the copolymer comprises from about 70% to about 81% alcohol units. 
     
     
         14 . The Structure of  claim 11  having a Cell Wall Thickness of from about 15 microns to about 55 microns. 
     
     
         15 . The Structure of  claim 11  having a Star Volume of from about 1 mm 3  to about 90 mm 3 . 
     
     
         16 . The Structure of  claim 15  having a Cell Wall Thickness of from about 20 microns to about 45 microns, a Star Volume of from about 10 mm 3  to about 70 mm 3  and a percent open cell content of from about 85% to about 97.5%. 
     
     
         17 . The Structure of  claim 11  comprising from about 5 wt % to about 65 wt % surfactant. 
     
     
         18 . The Structure of  claim 11  comprising an anionic surfactant. 
     
     
         19 . The Structure of  claim 11  having a porosity of from about 50% to about 98%. 
     
     
         20 . The Structure of  claim 1  comprising a significant number of fibers with average diameter less than about 150 microns. 
     
     
         21 . The Structure of  claim 20  wherein the copolymer comprises from about 65% to about 82.5% alcohol units. 
     
     
         22 . The Structure of  claim 21  wherein the copolymer comprises from about 70% to about 81% alcohol units. 
     
     
         23 . The Structure of  claim 20  comprising an anionic surfactant. 
     
     
         24 . The Structure of  claim 20  comprising a significant number of fibers with average diameter less than about 100 microns. 
     
     
         25 . The Structure of  claim 24  comprising a significant number of fibers with average diameter less than about 10 microns. 
     
     
         26 . A process for preparing a dissolvable open celled foam Structure, comprising the steps of:
 (a) preparing a pre-mixture comprising (1) from about 1 wt % to about 75 wt % surfactant, (2) from about 0.1 wt % to about 25 wt % of a vinyl acetate-vinyl alcohol copolymer, (3) not more than about 60 wt % water, and (4) optionally from about 0.1 wt % to about 25 plasticizer;
 wherein the pre-mixture: 
 (i) has a viscosity at 70° C. of from about 1000 cps to about 100,000 cps; and 
 (ii) is heated to a temperature in the range of from about 60° C. to about 100° C.; 
   (b) aerating the pre-mixture by introducing a gas into the pre-mixture to form a wet aerated mixture, wherein said wet aerated mixture comprises:
 (i) a density of from about 0.15 to about 0.65 g/ml; and 
 (ii) bubbles having a diameter of from about 5 to about 100 microns; 
   (c) dosing the wet aerated mixture into individual cavities in a mold or as a continuous sheet; and   (d) drying the wet aerated mixture by applying energy to heat the wet aerated mixture and evaporate water to provide a Structure;   wherein the Structure has a percent open cell of from about 70% to about 100%.   
     
     
         27 . A process for preparing a dissolvable fibrous web Structure, comprising the steps of:
 (a) preparing a processing mixture comprising one or more vinyl acetate-vinyl-alcohol copolymers; one or more surfactants; and not more than about 60 wt % water; wherein the processing mixture has: a viscosity at 70° C. of from about 5,000 centipoise to about 150,000 centipoise;   (b) fibrillating the processing mixture into fibers by a fluid film fibrillation process comprising a first pressurized gas stream directed against a liquid film of the processing mixture to form the fibers;   (c) at least partially drying the fibers of the processing mixture by a second pressurized gas stream;   (d) depositing the partially dry fibers on a surface to form a web of partially dry fibrous web structures; and   (e) drying the partially dry fibrous web structure to a desired final moisture content.