Synthetic surfactant-free finish, sheet having synthetic surfactant-free finish, articles having sheet with synthetic surfactant-free finish, and related methods
View Patent ↗Nonwoven (and film) topsheet and acquisition/distribution materials treated with a hydrophilic, synthetic surfactant-free finish, absorbent articles for infant or incontinence care that contain these materials, and methods for apply such finishes and/or making such absorbent articles.
1. A hydrophilic, synthetic sheet comprising:
a sheet of synthetic material having a first surface;
where the sheet comprises a hydrophilic finish including molecules of a water-soluble protein, where the water-soluble protein comprises a thermally denatured protein, dispersed on the first surface; and
where the finish is substantially free of synthetic surfactants, and
where a 0.4-10% aqueous solution of the water-soluble protein has a surface tension greater than 50 milliNewtons per meter (mN/m).
2. The sheet of claim 1 , where the finish does not include synthetic materials capable of reducing the surface tension of water below 50 milliNewtons/m (mN/m).
3. The sheet of claim 1 , where the sheet comprises a nonwoven fabric or a film.
4. The sheet of claim 1 , where the sheet is a topsheet of an absorbent article.
5. The sheet of claim 1 , where the sheet is a distribution-acquisition layer of an absorbent article.
6. The sheet of claim 1 , where a 0.4-1.2% aqueous solution of the water-soluble protein has a surface tension greater than 50 milliNewtons per meter (mN/m).
7. The sheet of claim 1 , where a 1.2-10% aqueous solution of the water-soluble protein has a surface tension greater than 50 milliNewtons per meter (mN/m).
8. The sheet of claim 1 , where at least 0.004 grams of the molecules of the water-soluble protein are dispersed on the sheet for each gram of sheet.
9. A method of imparting hydrophilic properties to a sheet of polymeric material, the method comprising:
applying a 0.4-10% aqueous solution of a water-soluble protein has a surface tension greater than 50 milliNewtons per meter (mN/m) to a sheet of polymeric material in an aqueous solution; and
drying the sheet such that at least a portion of the protein is retained on a surface of the sheet;
where the aqueous solution is substantially free of synthetic surfactants and where the water-soluble protein comprises a thermally denatured protein.
10. The method of claim 9 , where the sheet comprises a nonwoven fabric or a film.
11. The method of claim 9 , further comprising, prior to applying the aqueous solution to the sheet:
admixing the water-soluble protein in water;
heating the water to a temperature of between 40° Celsius (C) and 99° C.; and
stirring the admixture to dissolve the protein in the water.
12. The method of claim 11 , where the water is heated before admixing the water-soluble protein.
13. The method of claim 11 , where the temperature of the water is maintained between 40° C. and 99° C. during at least a portion of the stirring.
14. The method of claim 12 , where the temperature of the water is maintained between 40° C. and 99° C. for a period of time sufficient to thermally denature at least a portion of the protein.
15. The method of claim 11 , further comprising:
adjusting the pH of the admixture of water and protein prior to heating the temperature of the admixture.
16. The method of claim 9 , where the temperature of the solution is between 20° C. and 40° C. during at least a portion of applying the aqueous solution to the sheet.
17. The method of claim 9 , where applying the aqueous solution to the sheet comprises:
immersing the sheet a first time in the solution; and
immersing the sheet a second time in the solution.
18. The method of claim 17 , further comprising:
calendaring the sheet between immersing the sheet the first time and immersing the sheet the second time.
19. The method of claim 9 , where applying the aqueous solution to the sheet is performed with at least one coating apparatus selected from the group consisting of: a slot die, a knife coater, a kiss coater, a gravure printer, a multiple-roller coating apparatus, and a screen coating apparatus.
20. The method of claim 9 , where the aqueous solution comprises a preservative.
21. The method claim 20 , where the preservative comprises one or more preservatives selected from the group consisting of: Plantservative, MicroSilver, and Nutrabiol.
22. The method of claim 9 , where the protein comprises soy protein isolate (SPI).