Water-soluble polyvinyl alcohol blend film, related methods, and related articles
Disclosed herein are water-soluble films including a polyvinyl alcohol (PVOH) resin blend and optionally one or more additional components such as plasticizers, fillers, surfactants, and other additives. The PVOH resin blend includes a first copolymer including a first anionic monomer unit and a second PVOH copolymer including a second anionic monomer unit. When the PVOH copolymers are blended in particular proportions and/or selected with regard to various criteria related to physical and chemical film properties, the resulting water-soluble film formed from the PVOH resin blend exhibits maintained film stiffness, and pouch tautness when in contact with liquid pouch contents, maintain acceptable clarity properties, and/or demonstrate acceptable band release without impairing the ultimate solubility of the water-soluble film.
1. A water-soluble film comprising:
a polyvinyl alcohol (PVOH) resin blend comprising:
a first PVOH copolymer comprising a first anionic monomer unit, the first anionic monomer unit comprising maleic anhydride or an alkali metal salt of maleic anhydride, wherein the first anionic monomer unit is present in the first PVOH copolymer in an amount between about 1 mol % and about 3 mol %; and
a second PVOH copolymer comprising a second anionic monomer unit, the second anionic monomer unit comprising maleic anhydride or an alkali metal salt of maleic anhydride, wherein the second anionic monomer unit is present in the second PVOH copolymer in an amount between about 3 mol % and 10 mol %;
wherein the first PVOH copolymer is provided in the blend in an amount in a range of about 10 wt. % to about 70 wt. %, based on the total weight of the PVOH resin blend and the amount of first anionic monomer unit present in the first PVOH copolymer is different from the amount of second anionic monomer unit present in the second PVOH copolymer.
2. The water-soluble film of claim 1 , wherein the first PVOH copolymer is present in an amount in a range of about 10 wt. % to about 40 wt. % of total weight of the PVOH resin blend.
3. The water-soluble film of claim 1 , wherein the second PVOH copolymer is present in an amount in a range of about 30 wt. % to about 90 wt. % of total PVOH polymer in the film.
4. The water-soluble film of claim 1 , wherein the first PVOH copolymer is a maleic anhydride copolymer having a degree of maleic anhydride modification (b1) in an amount of about 1 mol % to about 3 mol %, based on the total moles of monomers in the copolymer, and the second PVOH copolymer is a maleic anhydride copolymer having a second degree of maleic anhydride modification (b2) in an amount of about 3 mol % to about 10 mol %, based on the total moles of monomers in the copolymer, wherein the difference between b1 and b2 is in a range of about 1 mol % to 3 mol %.
5. The water-soluble film of claim 1 , wherein the first PVOH copolymer has a 4% aqueous solution viscosity at 20° C. in a range of about 4 cP to about 30 cP.
6. The water-soluble film of claim 1 , wherein the second PVOH copolymer has a 4% aqueous solution viscosity at 20° C. in a range of about 12 cP to about 30 cP.
7. The water-soluble film claim 1 , wherein the water-soluble film has a residue value of about 20% or less as measured by the Dissolution Chamber Test.
8. The water-soluble film of claim 1 , wherein the water-soluble film has a crystallinity of at least 15%.
9. The water soluble film of claim 1 , wherein the PVOH resin blend consists essentially of the first PVOH copolymer and the second PVOH copolymer.
10. The water-soluble film of claim 1 , wherein the water-soluble film further comprises at least a third water-soluble polymer which is other than a PVOH polymer.
11. The water-soluble film of claim 10 , wherein the third water-soluble polymer is selected from one or more of a polyethyleneimine, a polyvinyl pyrrolidone, a polyalkylene oxide, a polyacrylamide, a cellulose ether, a cellulose ester, a cellulose amide, a polyvinyl acetate, a polyamide, a gelatine, a methylcellulose, a carboxymethylcellulose, a carboxymethylcellulose salt, a dextrin, an ethylcellulose, a hydroxyethyl cellulose, a hydroxypropyl methylcellulose, a maltodextrin, a starch, a modified starch, guar gum, gum Acacia, xanthan gum, carrageenan, a polyacrylate, a polyacrylate salt, and a copolymer of any of the foregoing.
12. The water-soluble film of claim 1 , wherein the first PVOH copolymer and the second PVOH copolymer each independently have a degree of hydrolysis in a range of about 75% to about 99%.
13. The water-soluble film of claim 1 , wherein the water-soluble film further comprises an auxiliary agent selected from one or more of a plasticizer, a plasticizer compatibilizer, a lubricant, a release agent, a filler, an extender, a cross-linking agent, an antiblocking agent, an antioxidant, a detackifying agent, an antifoam, a nanoparticle, a bleaching agent, and a surfactant.
14. The water-soluble film of claim 1 , further comprising one or more plasticizers in an amount of 30 phr or greater.
15. The water-soluble film of claim 1 , further comprising one or more plasticizers in an amount of less than 30 phr.
16. The water-soluble film of claim 1 , comprising a first plasticizer having a molecular weight of 92 g/mol or greater and a second plasticizer having a molecular weight of 150 g/mol or greater.
17. The water-soluble film of claim 16 , further comprising a third plasticizer.
18. The water-soluble film of claim 1 , further comprising a filler in an amount of at least 2 phr.
19. The water-soluble film of claim 18 , wherein the filler comprises a bulking agent, and antiblocking agent, or a combination thereof.
20. An article comprising:
the water-soluble film of claim 1 in the form of a pouch defining an interior pouch volume.
21. The article of claim 20 , further comprising a composition contained in the interior pouch volume.
22. The article of claim 21 , wherein the composition is a liquid composition.
23. The article of claim 22 , wherein the liquid composition is a liquid detergent.
24. The article of claim 22 , wherein the liquid composition comprises a low molecular weight polyol.
25. The article of claim 23 , wherein the article has a delayed release time of at least 30 seconds as measured by the Liquid Release Test.