Method for making soft tissue

• US 5,743,999 A
• Filed: 06/15/1994
• Issued: 04/28/1998
• Est. Priority Date: 04/12/1993
• Status: Expired due to Term

• Current Assignee: Kimberly-Clark Worldwide Incorporated (Kimberly-Clark Corporation)
• Original Assignee: Kimberly-Clark Worldwide Incorporated (Kimberly-Clark Corporation)
• Inventors: Kamps, Richard Joseph, Chen, Fung-Jou, Kressner, Bernhardt Edward, Nielsen, Janice Gail, Behnke, Janica Sue
• Primary Examiner(s): Chin, Peter
• Application Number:
  US08/259,824
• Time in Patent Office: 1,413 Days
• Field of Search: 162/109, 162/111, 162/113, 162/117
• US Class Current: 162/113
• CPC Class Codes: B31F 1/07 Embossing , i.e. producing impressions formed by locally deep-drawing, e.g. using rolls provided with complementary profilesB31F1/128 takes precedence; corrugating B31F1/20; embossing in combination with printing B41F19/02, B41M1/24; typewriters for embossing B41J3/38; stamping in combination with deforming B41K3/36
• CPC Class Codes: B31F 2201/0738 Cross sectional profile of the embossments
• CPC Class Codes: B31F 2201/0756 Characteristics of the incoming material, e.g. creped, embossed, corrugated
• CPC Class Codes: B31F 2201/0758 Characteristics of the embossed product
• CPC Class Codes: D21F 11/006 Making patterned paper
• CPC Class Codes: D21F 11/14 Making cellulose wadding, filter or blotting paper

Abstract

Paper sheets, such as creped tissue sheets used for converting into tissue products such as facial tissue and bath tissue, can be softened with by passing the sheets through one or more fixed-gap noncompactive straining nips formed between two engraved rolls having partially-engaged small straining elements of a shape which strains the sheet in all directions. The straining treatment substantially reduces the rigidity of the tissue sheet by increasing the internal bulk without substantially reducing the tensile strength. The method provides a means for making a throughdried-like tissue sheet from a wet-pressed tissue sheet.

Claims

1. A method of softening a wet-pressed, creped tissue sheet comprising passing the wet-pressed, creped tissue sheet through one or more noncompactive, fixed-gap straining nips, each nip formed between two engraved rolls having partially-engaged intermeshing straining elements which noncompactively strain the tissue sheet in all directions, wherein the Average Percent Void Area of the tissue sheet is increased about 1.5 percentage points or greater per 100 grams of geometric mean tensile strength loss without an increase in the external bulk of the tissue sheet.

2. The method of claim 1 wherein the Average Percent Void Area of the resulting tissue sheet is about 63 or greater.

3. The method of claim 1 wherein the number of straining nips is two or more.

4. The method of claim 3 wherein at least two straining nips have different degrees of engagement.

5. The method of claim 3 wherein at least two straining nips have different straining elements.

6. The method of claim 3 wherein the degree of engagement of the straining elements in a succeeding straining nip is less than the degree of engagement of the straining elements in the preceding straining nip.

7. The method of claim 3 wherein the degree of engagement of the straining elements in a succeeding straining nip is about the same as the degree of engagement of the straining elements in the preceding straining nip.

8. The method of claim 3 wherein the degree of engagement of the straining elements in a succeeding straining nip is greater than the degree of engagement of the straining elements in the preceding straining nip.

9. The method of claim 1 wherein the number of straining nips is three or more.

10. The method of claim 1 wherein the number of straining nips is six or more.

11. The method of claim 1 wherein the straining elements have a round shape as viewed perpendicular to the surface of the straining roll.

12. The method of claim 1 wherein the straining elements have an oblong shape as viewed perpendicular to the surface of the straining roll.

13. The method of claim 1 wherein the number of straining elements per unit length in the circumferential direction of the straining rolls is greater than the number of straining elements per unit length in the axial direction of the straining rolls.

14. The method of claim 1 wherein the number of straining elements per unit length in the circumferential direction of the straining rolls is less than the number of straining elements per unit length in the axial direction of the straining rolls.

15. The method of claim 1 wherein the number of straining elements per unit length in the circumferential direction of the straining rolls is equal to the number of straining elements per unit length in axial direction of the straining rolls.

16. The method of claim 1 wherein the increase in the Average Percent Void Area of the tissue sheet is about 2 percentage points or greater per 100 grams of geometric mean tensile strength loss.

17. The method of claim 1 wherein the increase in the Average Percent Void Area of the tissue sheet is about 3 percentage points or greater per 100 grams of geometric mean tensile strength loss.