Water-dispersible thermoplastic injection molded composition

Patent metadata

Field	Value
Publication number	US-9320656-B2
Application number	US-201314092013-A
Country	US
Kind code	B2
Filing date	Nov 27, 2013
Priority date	Nov 27, 2013
Publication date	Apr 26, 2016
Grant date	Apr 26, 2016

Abstract

A thermoplastic composition that is water-sensitive (e.g., water-soluble, water-dispersible, etc.) in that it loses its integrity over time in the presence of water that can also be injection molded is provided. The composition contains a cellulose derivative, a synthetic water-soluble polymer, and a plasticizer. The desired water-sensitive and moldable attributes of the composition may be achieved in the present invention by selectively controlling a variety of aspects of the composition, such as the nature of the components employed, the relative amount of each component, the manner in which the composition is formed, and so forth.

First claim

What is claimed is:

1. A water-dispersible composition, the composition comprising:
from about 7 wt. % to about 70 wt. % of at least one cellulose derivative, wherein the at least one cellulose derivative includes hydroxypropyl methylcellulose;
from about 7 wt. % to about 70 wt. % of at least one synthetic water-soluble polymer; and
from about 2 wt. % to about 50 wt. % of at least one plasticizer based on the total weight of the composition, wherein the weight percentage ratio of the synthetic water-soluble polymer to the cellulose derivative ranges from about 0.1 to about 10, further wherein the composition is thermoplastic.

2. The composition of claim 1 , wherein the cellulose derivative constitutes from about 20 wt. % to about 60 wt. % of the composition based on the total weight of the composition.

3. The composition of claim 1 , wherein the synthetic water-soluble polymer constitutes from about 20 wt. % to about 60 wt. % of the composition based on the total weight of the composition.

4. The composition of claim 1 , wherein the plasticizer constitutes from about 5 wt. % to about 40 wt. % of the composition based on the total weight of the composition.

5. The composition of claim 1 , wherein the weight percentage ratio of the synthetic water-soluble polymer to the cellulose derivative ranges from about 0.3 to about 3.

6. The composition of claim 1 , wherein the hydroxypropyl methylcellulose has a methoxyl content of from about 10% to about 40%.

7. The composition of claim 1 , wherein the hydroxypropyl methylcellulose has a hydroxypropyl content of from about 1% to about 15%.

8. The composition of claim 1 , wherein the hydroxypropyl methylcellulose has a viscosity ranging from about 1,000 mPa·s to about 75,000 mPa·s for a 2% aqueous solution at 20° C.

9. The composition of claim 1 , wherein the synthetic water-soluble polymer is a vinyl alcohol polymer.

10. The composition of claim 9 , wherein the vinyl alcohol polymer is partially hydrolyzed.

11. The composition of claim 10 , wherein the vinyl alcohol polymer has a degree of hydrolysis of from about 80 mole % to about 90 mole %.

12. The composition of claim 1 , wherein the plasticizer is a polyhydric alcohol.

13. The composition of claim 12 , wherein the plasticizer is a polyol.

14. The composition of claim 13 , wherein the plasticizer is ethylene glycol, glycerol, propylene glycol, dipropylene glycol, butylene glycol, hexane triol, or a combination thereof.

15. The composition of claim 1 , further comprising from about 0.5 wt. % to about 35 wt. % of an inorganic particulate filler based on the total weight of the composition.

16. The composition of claim 15 , wherein the inorganic particulate filler comprises calcium carbonate, kaolin clay, silica, alumina, barium carbonate, sodium carbonate, titanium dioxide, zeolites, magnesium carbonate, calcium oxide, magnesium oxide, aluminum hydroxide, talc, or a combination thereof.

17. The composition of claim 1 , wherein the composition exhibits a melt flow index of from about 10 grams per 10 minutes to about 150 grams per 10 minutes when subjected to a load of 2160 grams at a temperature of 190° C. according to ASTM Test Method D1238-E.

18. The composition of claim 1 , wherein the composition is injection moldable.

19. A molded article comprising the composition of claim 1 .

20. The molded article of claim 19 , wherein the molded article disintegrates in still tap water in less than about 18 hours.

21. The molded article of claim 19 , wherein the molded article is a tampon applicator.

22. A method for forming an injection molded part, the method comprising:
injecting a water-dispersible, thermoplastic composition into a mold cavity, wherein the thermoplastic composition comprises from about 7 wt. % to about 70 wt. % of a cellulose derivative, from about 7 wt. % to about 70 wt. % of a synthetic water-soluble polymer, wherein the synthetic water-soluble polymer comprises polyvinyl alcohol, and from about 2 wt. % to about 50 wt. % of a plasticizer; and
shaping the thermoplastic composition into a molded part within the mold cavity.

23. The method of claim 22 , further comprising coating the injection molded part with a water-insoluble coating.

24. The method of claim 22 , further comprising a co-injection molding process, wherein the injection molded part is a two layered molded part having an inner layer and an outer layer, wherein the inner layer comprises the injection-molded, thermoplastic composition and the outer layer is water-insoluble.

25. The method of claim 24 , wherein the outer layer comprises from about 1 wt. % to about 50 wt. % of the injection molded part and the inner layer comprises from about 50 wt. % to about 99 wt. % of the injection molded part.

26. The method of claim 24 , wherein the outer layer comprises a wax, silicon, polytetrafluoroethylene, polyethylene, a polyester, polyamide, a thermoplastic elastomer, or a combination thereof.

27. The method of claim 22 , wherein the cellulose derivative comprises hydroxypropyl methylcellulose.

28. The method of claim 22 , wherein the molded part is a tampon applicator.

Assignees

• Kimberly Clark Co

Inventors

• Wang James H
• Wideman Gregory J
• Mleziva Mark M

Classifications

• C08L1/284

  with hydroxylated hydrocarbon radicals · CPC title

• C08L29/04

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

• C08K3/26

  Carbonates; Bicarbonates · CPC title

• B29L2023/00

  Tubular articles (B29L2024/00 takes precedence {; catheters B29L2031/7542}) · CPC title

• B29K2995/0062

  water-soluble · CPC title