Water-soluble film having improved dissolution and stress properties, and packets made therefrom
Disclosed is a pouch having at least one sealed compartment containing a first composition. At least one wall of the at least one sealed compartment is made from a water-soluble film having any suitable thickness. The water-soluble film comprises PVOH polymer such that when the film has a thickness of about 76 microns the film is characterized by a Dissolution Index of about 620 to about 920, or of about 665 to about 920, or about 710 to about 920; and a Stress Index of about 145 to about 626, or about 155 to about 480, or about 165 to about 325.
1. A water-soluble film having any suitable thickness, the water-soluble film comprising:
at least 50 wt. % of a water-soluble polyvinyl alcohol (PVOH) resin, the PVOH resin having an average viscosity in a range of about 13.5 cP to about 20 cP and a degree of hydrolysis in a range of about 84% to about 92%; and
the film further having no more than 30 wt. % of a PVOH polymer having an average viscosity less than about 11 cP;
the film further characterized by having a Dissolution Index in a range of about 620 to about 920 and a Stress Index in a range of about 145 to about 626 when the film has a thickness of about 76 microns,
wherein the film is thermoformable.
2. The water-soluble film of claim 1 , wherein the PVOH resin comprises a first PVOH polymer having a viscosity in a range of about 8 cP to about 40 cP and a second PVOH polymer having a viscosity in a range of about 10 cP to about 40 cP, wherein the viscosity of the first PVOH polymer is less than the viscosity of the second PVOH polymer.
3. The water-soluble film of claim 2 , wherein the first PVOH polymer has a viscosity in a range of about 10 cP to about 20 cP.
4. The water-soluble film of claim 3 , wherein the first PVOH polymer has a viscosity in a range of about 10 cP to about 15 cP.
5. The water-soluble film of claim 2 , wherein the second PVOH polymer has a viscosity in a range of about 20 cP to about 30 cP.
6. The water-soluble film of claim 5 , wherein the second PVOH polymer has a viscosity in a range of about 20 cP to about 25 cP.
7. The water-soluble film of claim 1 further comprising about 1 wt. % to about 40 wt. % of a plasticizer.
8. The water-soluble film of claim 7 , wherein the plasticizer comprises a material selected from the group consisting of glycerin, sorbitol, propylene glycol, 2-methyl-1,3-propanediol, and a mixture thereof.
9. The water-soluble film of claim 7 , wherein the film comprises about 15 wt. % to about 35 wt. % of the plasticizer.
10. The water-soluble film of claim 1 further comprising a residual moisture content in a range of about 4 wt. % to about 10 wt. %.
11. The water-soluble film of claim 1 , wherein the Dissolution Index is in a range about 665 to about 920.
12. The water-soluble film of claim 11 , wherein the Dissolution Index is in a range of about 710 to about 920.
13. The water-soluble film of claim 1 , wherein the Stress Index is in a range of about 155 to about 480.
14. The water-soluble film of claim 13 , wherein the Stress Index is in a range of about 165 to about 325.
15. The water-soluble film of claim 1 further characterized by a Burst Strength Test value of greater than about 20 seconds when the film has a thickness of about 76 microns.
16. The water-soluble film of claim 15 , wherein the Burst Strength Test value is greater than about 30 seconds.
17. The water-soluble film of claim 1 , wherein the resin is characterized by a Resin Selection Index value in a range of 0.255 to 0.315.
18. A water-soluble film comprising:
at least 50 wt. % of a PVOH resin, the resin having an average viscosity in a range of about 13.5 cP to about 20 cP and a degree of hydrolysis in a range of about 84% to about 90%; the resin comprising a blend of first and second PVOH polymers, the first PVOH polymer having a viscosity in a range of about 8 cP to about 40 cP, the second PVOH polymer having a viscosity in a range of about 10 cP to about 40 cP, and the viscosity of the first PVOH polymer being less than the viscosity of the second PVOH polymer;
about 10 wt. % to about 40 wt. % of a plasticizer;
a residual moisture content of at least 4 wt. %; and
the film further having no more than 30 wt. % of a PVOH polymer having an average viscosity less than about 11 cP;
the film further characterized by a Dissolution Index of about 620 to about 920 and a Stress Index of about 145 to about 626 when the film has a thickness of about 76 microns.
19. The water-soluble film of claim 18 , wherein the residual moisture content is in a range of about 4 wt. % to about 10 wt. %.
20. A water-soluble film comprising:
at least 50 wt. % of a PVOH resin characterized by a Resin Selection Index value in a range of 0.255 to 0.315, the resin comprising a blend of first and second PVOH polymers, the first PVOH polymer having a viscosity in a range of about 8 cP to about 40 cP, the second PVOH polymer having a viscosity in a range of about 10 cP to about 40 cP, and the viscosity of the first PVOH polymer being less than the viscosity of the second PVOH polymer;
about 10 wt. % to about 40 wt. % of a plasticizer; and
the film further having no more than 30 wt. % of a PVOH polymer having an average viscosity less than about 11 cP;
the film further characterized by a Dissolution Index of about 620 to about 920 and a Stress Index of about 145 to about 626 when the film has a thickness of about 76 microns.
21. The water-soluble film of claim 20 , wherein the Resin Selection Index value is in a range of 0.260 to 0.310.
22. The water-soluble film of claim 21 , wherein the Resin Selection Index value is in a range of 0.265 to 0.305.
23. The water-soluble film of claim 22 , wherein the Resin Selection Index value is in a range of 0.270 to 0.300.
24. A pouch comprising the water-soluble film of claim 1 .
25. The pouch of claim 24 comprising two or more compartments.