Use of a first film and a second film to improve seal strength of a water-soluble unit dose article

1. A water-soluble unit dose article comprising

a first water-soluble film comprising a first water soluble resin, wherein the first water soluble resin comprises a blend of a polyvinyl alcohol homopolymer, and a polyvinyl alcohol copolymer comprising a carboxylated, anionic monomer unit;

and a second water-soluble film comprising a second water soluble resin, wherein the second water soluble resin comprises a blend of a polyvinyl alcohol homopolymer, and a polyvinyl alcohol copolymer comprising a carboxylated, anionic monomer unit;

and, optionally comprising a composition contained within the unit dose article, wherein the first water-soluble film and the second water-soluble film are sealed together along a seal area, in order to improve the seal strength in the seal area;

wherein the first water-soluble film and the second water-soluble film are chemically different to one another and wherein the first water-soluble film has a first water capacity and a first tensile strain at break, and wherein the second water-soluble film has a second water capacity and a second tensile strain at break, wherein the first water capacity is less than the second water capacity, wherein the difference between the water capacity of the first water soluble film and the second water-soluble film is between 0.01% and 1%, wherein the first tensile strain at break is greater than the second tensile strain at break, and the difference between the first tensile strain at break and the second tensile strain at break is from 10% to 1000%;

provided that when the composition is a fabric care or household care composition and a film comprises a blend of a polyvinyl alcohol homopolymer resin and an anionic polyvinyl alcohol copolymer resin, then both the first water soluble film and the second water soluble film comprise blends that include 65 wt. % or greater of a carboxylated anionic polyvinyl alcohol copolymer resin; and

provided that when the composition is a fabric care or household care composition and a film further comprises a second carboxylated anionic polyvinyl alcohol copolymer resin, then both the first water soluble film and the second water soluble film further comprise a second carboxylated anionic polyvinyl alcohol copolymer resin.

2. The water-soluble unit dose article according to claim 1 , wherein the first water-soluble film has a water capacity from 1% to 10%.

3. The water-soluble unit dose article according to claim 2 , wherein the first water-soluble film has a water capacity from 3% to 6%.

4. The water-soluble unit dose article according to claim 1 , wherein the second water-soluble film has a water capacity from 1.5% to 12%.

5. The water-soluble unit dose article according to claim 1 , wherein the difference in water capacity is from 0.03% to 0.5%.

6. The water-soluble unit dose article of claim 1 , wherein the first water soluble resin comprises from 65% by weight or greater of the first water soluble resin of the polyvinyl alcohol copolymer comprising the carboxylated anionic monomer unit and the second water soluble resin comprises from 65% by weight or greater of the second water soluble resin of the polyvinyl alcohol copolymer comprising the carboxylated anionic monomer unit.

7. The water-soluble unit dose article according to claim 6 , wherein the carboxylated, anionic monomer unit is derived from a monomer selected from the group consisting of vinyl acetic acid, alkyl acrylates, maleic acid, monoalkyl maleate, dialkyl maleate, monomethyl maleate, dimethyl maleate, maleic anhydride, fumaric acid, monoalkyl fumarate, dialkyl fumarate, monomethyl fumarate, dimethyl fumarate, fumaric anhydride, itaconic acid, monomethyl itaconate, dimethyl itaconate, itaconic anhydride, citraconic acid, monoalkyl citraconate, dialkyl citraconate, citraconic anhydride, mesaconic acid, monoalkyl mesaconate, dialkyl mesaconate, mesaconic anhydride, glutaconic acid, monoalkyl glutaconate, dialkyl glutaconate, glutaconic anhydride, alkali metal salts thereof, esters thereof, and combinations thereof.

8. The water-soluble unit dose article according to claim 1 , wherein the first water-soluble film, and the second water-soluble film independently have a thickness before incorporation into the unit dose article of between 40 microns and 100 microns.

9. The water-soluble unit dose article according to claim 1 , wherein the first water-soluble film has a first tensile strain at break of between 300% and 1600% and the second water-soluble film has a second tensile strain at break of between 300 and 1200%.

10. The water-soluble unit dose article according to claim 1 , wherein the unit dose comprises a detergent composition.

11. The water-soluble unit dose article according to claim 10 , wherein the water-soluble unit dose article is disposed in a storage receptacle.

12. The water-soluble unit dose article according to claim 11 , wherein the storage receptacle is a flexible bag, a rigid tub or a mixture thereof.

13. The water-soluble unit dose article according to claim 1 , wherein the unit dose article contains a non-household care composition.

14. The water-soluble unit dose article according to claim 13 , wherein the non-household care composition is selected from agricultural compositions, aviation compositions, food and nutritive compositions, industrial compositions, livestock compositions, marine compositions, medical compositions, mercantile compositions, military and quasi-military compositions, office compositions, and recreational and park compositions, pet compositions, water-treatment compositions.

15. The water-soluble unit dose article according to claim 14 , wherein the non-household care composition comprises an agricultural composition.

16. The water-soluble unit dose article according to claim 14 , wherein the non-household care composition comprises a water-treatment composition.

17. A process for dosing a unit dose article comprising:

obtaining a water-soluble unit dose article according to claim 1 and

contacting the water-soluble unit dose article with water to dissolve at least a portion of a film thereof, thereby releasing the composition.

18. The process according to claim 17 , wherein the first water-soluble film has a water capacity from 1% to 10%.

19. The process according to claim 17 , wherein the second water-soluble film has a water capacity from 1.5% to 12%.

20. The process according to claim 17 wherein the difference in water capacity is from 0.03% to 0.5%.

21. The process according to claim 17 , wherein obtaining the water-soluble unit dose article comprises a user transferring at least one water-soluble unit dose article from a storage receptacle.

22. The process according to claim 21 , wherein the transferring is by hand.

23. The process according to claim 17 , wherein said contacting comprises the addition of between 10 L and 60 L water.

24. The process according to claim 17 , wherein the contacting takes between 5 minutes and 90 minutes.

25. The process according to claim 17 , wherein the water has a temperature between 10° C. and 45° C.

26. The process according to claim 17 , wherein the first water soluble resin comprises from 65% by weight or greater of the first water soluble resin of the polyvinyl alcohol copolymer comprising the carboxylated anionic monomer unit and the second water soluble resin comprises from 65% by weight or greater of the second water soluble resin of the polyvinyl alcohol copolymer comprising the carboxylated anionic monomer unit.

27. The process according to claim 26 , wherein the carboxylated, anionic monomer unit is derived from a monomer selected from the group consisting of vinyl acetic acid, alkyl acrylates, maleic acid, monoalkyl maleate, dialkyl maleate, monomethyl maleate, dimethyl maleate, maleic anhydride, fumaric acid, monoalkyl fumarate, dialkyl fumarate, monomethyl fumarate, dimethyl fumarate, fumaric anhydride, itaconic acid, monomethyl itaconate, dimethyl itaconate, itaconic anhydride, citraconic acid, monoalkyl citraconate, dialkyl citraconate, citraconic anhydride, mesaconic acid, monoalkyl mesaconate, dialkyl mesaconate, mesaconic anhydride, glutaconic acid, monoalkyl glutaconate, dialkyl glutaconate, glutaconic anhydride, alkali metal salts thereof, esters thereof, and combinations thereof.

28. The process according to claim 17 , wherein the first water-soluble film is thermoformed during manufacture of the unit dose article.

29. The process according to claim 17 , wherein the first water-soluble film, and the second water-soluble film independently have a thickness before incorporation into the unit dose article of between 40 microns and 100 microns.

30. The process according to claim 17 , wherein the first water-soluble film has a first tensile strain at break of between 300% and 1600% and the second water-soluble film has a second tensile strain at break of between 300 and 1200%.