Compositions in the Form of Dissolvable Solid Structures
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.
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.