Flash curing of fibrous webs treated with polymeric reactive compounds

• US 6,264,791 B1
• Filed: 10/25/1999
• Issued: 07/24/2001
• Est. Priority Date: 10/25/1999
• Status: Expired due to Fees

• Current Assignee: The Research Foundation for The State University of New York (State University of New York)
• Original Assignee: Kimberly-Clark Worldwide Incorporated (Kimberly-Clark Corporation)
• Inventors: Sun, Tong, Lindsay, Jeffrey D.
• Primary Examiner(s): Silverman, Stanley S.
• Assistant Examiner(s): Halpern, Mark
• Application Number:
  US09/425,810
• Time in Patent Office: 638 Days
• Field of Search: 162/168.1, 162/168.3, 162/184, 162/185, 162/164.1, 162/157.1, 162/157.6, 162/158, 162/9, 162/17, 162/19, 162/100, 811/61
• US Class Current: 162/168.1
• CPC Class Codes: D04H 1/425 Cellulose series
• CPC Class Codes: D04H 1/587 characterised by the bonding agents used
• CPC Class Codes: D04H 1/655 characterised by the apparatus for applying bonding agents
• CPC Class Codes: D04H 1/732 by fluid current, e.g. air-lay
• CPC Class Codes: D21H 21/20 Wet strength agents
• CPC Class Codes: D21H 25/06 of impregnated or coated paper D21H25/08 takes precedence

Abstract

Methods for making high wet performance webs. A polymeric anionic reactive compound is applied to a cellulosic fibrous web followed by flash curing of the compound to crosslink the cellulose fibers. The resulting tissue has high wet resiliency, high wet strength, and a high wet:dry tensile strength ratio.

Claims

1. A method for making a high wet performance paper web comprising:

forming a web comprising cellulosic papermaking fibers;

treating the web with an aqueous solution of a polymeric anionic reactive compound (PARC);

flash curing the treated web by heating the web to a temperature above 160°

C. for less than 1 minute so that covalent bonds form between the PARC and the cellulosic fibers.

2. The method of claim 1, wherein the time of flash curing is less than about 15 seconds.

3. The method of claim 1, wherein the time of flash curing is less than about 5 seconds.

4. The method of claim 1, wherein the time of flash curing is less than about 1 second.

5. The method of claim 1, wherein the step of flash curing comprises exposing the web to a gas heated to a temperature in the range of about 200°

C. to 350°

C.

6. The method of claim 1 wherein the step of flash curing comprises exposing the web to a gas heated to a temperature in the range of about 250°

C. to 320°

C.

7. The method of claim 1, wherein the step of flash curing comprises passing a heated gas through the web.

8. The method of claim 1, wherein the step of flash curing comprises impinging heated gas on a surface of the web.

9. The method of claim 1, wherein the step of flash curing comprises contacting the web with a heated surface.

10. The method of claim 1, wherein the step of flash curing comprises exposing the web to infrared radiation.

11. The method of claim 1, wherein the step of flash curing comprises applying microwave energy or radiofrequency energy to the web.

12. The method of claim 1, wherein the PARC serves to form crosslinks between the cellulosic fibers.

13. The method of claim 1, wherein the step of treating the web with an aqueous solution of a PARC comprises a method selected from the group consisting of coating, printing, and spraying.

14. The method of claim 1, wherein the PARC comprises a polymeric compound having repeating units containing two or more anionic functional groups that will covalently bond to hydroxyl groups of the cellulosic fibers.

15. The method of claim 14, wherein the functional groups are carboxylic acids.

16. The method of claim 14, wherein the carboxylic acids are on adjacent carbons and are capable of forming a cyclic anhydride.

17. The method of claim 1, wherein the PARC is a polymer comprising maleic acid.

18. The method of claim 1, wherein the aqueous solution is applied in an amount from about 50 to 200 percent add-on.

19. The method of claim 1, wherein the aqueous solution is applied in an amount from about 0.3 to 8% by weight of the dry web.

20. The method of claim 1, wherein the aqueous solution is applied in an amount from about 0.7 to 2% by weight of the dry web.

23. The method of claim 1, wherein the wet tensile strength index of the treated and cured paper is at least about 0.7 Nm/g.

24. The method of claim 1, wherein the wet tensile strength index of the treated and cured paper is between about 0.8 Nm/g to about 1.6 Nm/g.

27. The method of claim 1 further comprising the step of drying the web prior to application of the PARC.

28. The method of claim 1, wherein the aqueous solution further comprises a catalyst selected from the group consisting of alkali metal hypophosphites, alkali metal phosphites, alkali metal polyphosphonates, alkali metal phosphates, and alkali metal sulfonates.

29. The method of claim 1, wherein the aqueous solution is substantially free of formaldehyde or of cross-linking agents that evolve formaldehyde.

30. The method of claim 1, wherein the PARC has a molecular weight of about 5,000 or less.

31. The method of claim 1, wherein the PARC has a molecular weight of from about 500 to 2000.

35. The method of claim 1, further comprising treating the web with a chemical debonder.

37. A high wet performance paper web produced according to the method of claim 1.

38. The paper web of claim 37, wherein the wet tensile strength index of the treated and cured paper is at least about 0.7 Nm/g.

39. The paper web of claim 37, wherein the wet tensile strength index of the treated and cured paper is between about 0.8 Nm/g to about 1.6 Nm/g.

40. The paper web of claim 37, wherein the wet:

dry ratio of the treated and cured paper web is at least about 20%.

41. The paper web of claim 37, wherein the wet:

dry ratio of the treated and cured paper web is at least about 40%.

42. The paper web of claim 37, wherein the web has a weight basis of between about 40 and 60 grams per square meter (gsm) and has a wet tensile strength of at least about 200 g/3 in.

43. The paper web of claim 37, wherein the web has a weight basis of between about 40 and 60 grams per square meter (gsm) and has a wet tensile strength of at least about 800 g/3 in.

44. An absorbent article comprising the paper web of claim 37.

45. The paper of claim 37, wherein the paper is substantially free of latex.

46. A premoistened tissue comprising a web produced according to the method of claim 1.

47. The method of claim 1, wherein forming the web comprises providing an aqueous slurry of papermaking fibers, depositing the slurry on a moving fabric, and dewatering the slurry to form a web.

48. The method of claim 47, wherein forming the web further comprises drying the web prior to treating the web with the aqueous PARC solution.

21. A method for making a high wet performance paper web comprising:

forming a web comprising cellulosic papermaking fibers;

treating the web with an aqueous solution of a polymeric anionic reactive compound (PARC);

flash curing the treated web so that covalent bonds form between the PARC and the cellulosic fibers, wherein the treated web is dried prior to curing to a dryness level of about 90% or higher.

22. The method of claim 21, wherein the treated web is dried at a temperature less than about 150°

C.

25. A method for making a high wet performance paper web comprising:

forming a web comprising cellulosic papermaking fibers;

treating the web with an aqueous solution of a polymeric anionic reactive compound (PARC);

flash curing the treated web so that covalent bonds form between the PARC and the cellulosic fibers, wherein the wet;

dry ratio of the treated and cured paper is at least about 20%.

26. The method of claim 25, wherein the wet:

dry ratio of the treated and cured paper is at least about 40%.

49. The method of claim 25, further comprising treating the web with a chemical debonder.

50. A high wet performance paper web produced according to the method of claim 25.

32. A method for making a high wet performance paper web comprising:

forming a web comprising cellulosic papermaking fibers;

treating the web with an aqueous solution of a polymeric anionic reactive compound (PARC);

flash curing the treated web so that covalent bonds form between the PARC and the cellulosic fibers, wherein the PARC solution has a pH of about 3 or greater.

33. The method of claim 32, wherein the PARC solution has a pH of about 4 or greater.

34. A method for making a high wet performance paper web comprising:

forming a web comprising cellulosic papermaking fibers;

treating the web with an aqueous solution of a polymeric anionic reactive compound (PARC);

flash curing the treated web so that covalent bonds form between the PARC and the cellulosic fibers, wherein the PARC solution has a viscosity as applied of about 10 centipoise or less.

36. A method for making a high wet performance paper web comprising:

forming a web comprising cellulosic papermaking fibers;

treating the web with an aqueous solution of a polymeric anionic reactive compound (PARC);

flash curing the treated web so that covalent bonds form between the PARC and the cellulosic fibers, wherein the PARC has a viscosity of 100 centipoise or less at 25°

C. and at a concentration in water of 50% by weight or as high as can be dissolved.