Water-soluble film, method of manufacturing same, and package

Patent metadata

Field	Value
Publication number	US-12344718-B2
Application number	US-202117359952-A
Country	US
Kind code	B2
Filing date	Jun 28, 2021
Priority date	Dec 28, 2018
Publication date	Jul 1, 2025
Grant date	Jul 1, 2025

Abstract

Provided are a water-soluble film having excellent solubility in water and capable of reducing the stickiness of the contact surfaces to each other at the edges during storage in rolls, a production method thereof, and a package using the water-soluble film. A water-soluble film of the present invention includes a polyvinyl alcohol resin. The water-soluble film satisfies a formula (1) below when amounts of crystalline component are respectively (A1) 0 , (A1) 60 , and (A1) 180 , the amounts being obtained from a spin-spin relaxation curve by 1 H pulse NMR measurement of the water-soluble film immediately after, 60 seconds after, and 180 seconds after the water-soluble film is immersed in a mixed solution of deuterated water and deuterated methanol mixed at a volume ratio of 1:1 at 5° C.

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First claim

The invention claimed is:

1. A water-soluble film comprising a polyvinyl alcohol resin, wherein
the water-soluble film satisfies Formula (1) below,
Formula (1)
0.2<( A 1) 60 /( A 1) 0 <0.6and( A 1) 180 /( A 1) 0 <( A 1) 60 /( A 1) 0   (1)

in which (A1) 0 , (A1) 60 , and (A1) 180 , are amounts of crystalline component obtained from a spin-spin relaxation curve measured by 1 H pulse NMR measurement of the water-soluble film immediately after, 60 seconds after, and 180 seconds, respectively, after the water-soluble film is immersed in a mixed solution of deuterated water and deuterated methanol mixed at a volume ratio of 1:1 at 5° C.

2. The water-soluble film according to claim 1 , wherein the water-soluble film further satisfies Formula (2) below:
Formula (2)
( A 1) 180 /( A 1) 0 <0.3  (2).

3. The water-soluble film according to claim 1 , wherein the amount (A1) 0 of crystalline component is 80% or less, and an amount (A2) 0 of constrained amorphous component is from 5% to 30%, where the amount (A2) 0 of constrained amorphous component is obtained from the spin-spin relaxation curve immediately after the water-soluble film is immersed in the mixed solution.

4. The water-soluble film according to claim 3 , wherein a ratio (A1/A2) 0 of the amount (A1) 0 of crystalline component to the amount (A2) 0 of constrained amorphous component is from 1 to 20.

5. The water-soluble film according to claim 1 , wherein rupture time when the water-soluble film is immersed in deionized water at 30° C. is from 10 to 100 seconds.

6. A method of producing the water-soluble film according to claim 1 , comprising:
preparing a film forming stock solution containing the polyvinyl alcohol resin and a solvent;
forming a liquid coating by feeding the film forming stock solution on a rotating support; and
obtaining the water-soluble film by removing the solvent from the liquid coating on the support.

7. The method of producing the water-soluble film according to claim 6 , wherein the film forming stock solution further contains 10 parts by mass or more of a plasticizer based on 100 parts by mass of the polyvinyl alcohol resin.

8. The method of producing the water-soluble film according to claim 6 , wherein S1/S0 is 7 or less, where S0, m/second, is a feeding rate of the film forming stock solution on the support, and S1, m/second, is a rotation speed of the support.

9. The method of producing the water-soluble film according to claim 6 , wherein the support has a surface temperature from 50° C. to 110° C.

10. The method of producing the water-soluble film according to claim 6 , further comprising heat treating the water-soluble film thus obtained at a temperature from 60° C. to 135° C.

11. A package comprising:
a packaging material composed of the water-soluble film according to claim 1 ; and
a chemical encapsulated in the packaging material.

12. The package according to claim 11 , wherein the chemical is a pesticide, a detergent, or a germicide.

13. The water-soluble film according to claim 1 ,
wherein the water-soluble film is produced by a process comprising feeding a film forming stock solution on a rotating support, and the film forming stock solution includes the polyvinyl alcohol resin, and
wherein the support has a surface temperature from 65° C. to 110° C.

14. The water-soluble film according to claim 13 , wherein S1/S0 is more than 3 and 6.8 or less, where S0, m/second, is a feeding rate of the film forming stock solution on the support, and S1, m/second, is a rotation speed of the support.

15. The water-soluble film according to claim 1 , wherein the polyvinyl alcohol resin includes a maleic acid monomethyl ester (MMM) modified polyvinyl alcohol.

16. The water-soluble film according to claim 1 , wherein the polyvinyl alcohol resin has a degree of polymerization of 500 to 3,000.

17. The water-soluble film according to claim 1 , wherein the polyvinyl alcohol resin has a degree of saponification of 60 to 99.9 mol %.

18. The water-soluble film according to claim 1 , wherein the water-soluble film comprises a single polyvinyl alcohol resin or two or more polyvinyl alcohol resins having a degree of polymerization, a degree of saponification, and/or a degree of modification different from each other.

19. The water-soluble film according to claim 18 , wherein the water-soluble film comprises the single polyvinyl alcohol resin, and the single polyvinyl alcohol resin includes a maleic acid monomethyl ester (MMM) modified polyvinyl alcohol.

20. The method of producing the water-soluble film according to claim 6 , wherein the film forming stock solution further includes 10 parts by mass to 70 parts by mass of a plasticizer based on 100 parts by mass of the polyvinyl alcohol resin.

Assignees

• Kuraray Co

Inventors

• Okamoto Minoru
• Shimizu Sayaka
• Kazeto Osamu

Classifications

• C08J2329/04

  Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids · CPC title

• B65D65/46

  Applications of disintegrable, dissolvable or edible materials · CPC title

• B29L2031/712

  Containers; Packaging elements or accessories, Packages (closures therefor B29L2031/56; ink or toner cartridges B29L2031/7678; squeeze tubes B29L2023/20; suitcases B29L2031/7418) · CPC title

• B29L2007/008

  Wide strips, e.g. films, webs · CPC title

• B29K2995/0062

  water-soluble · CPC title