Absorbent unitary laminate-like fibrous webs and method for producing them

• US 3,879,257 A
• Filed: 04/30/1973
• Issued: 04/22/1975
• Est. Priority Date: 04/30/1973
• Status: Expired due to Term

• Current Assignee: Clifford J. Roberts Jr, Gunnar E. Steward, Nicholas A. Jappe, Richard R. Hepford, Victor R. Gentile
• Original Assignee: Clifford J. Roberts Jr, Gunnar E. Steward, Nicholas A. Jappe, Richard R. Hepford, Victor R. Gentile
• Inventors: Roberts, Clifford J. Jr., Gentile, Victor R., Hepford, Richard R., Jappe, Nicholas A., Steward, Gunnar E.
• Primary Examiner(s): Lesmes, George F.
• Assistant Examiner(s): Thibodeau, Paul J.
• Application Number:
  US05/356,052
• Time in Patent Office: 722 Days
• Field of Search: 161/128,129,146,148,268 156/183 264/282,283 162/112,184,231,135,111
• US Class Current: 162/112
• CPC Class Codes: B31F 1/126 including making of the paper to be crêped
• CPC Class Codes: D21F 11/04 paper or board consisting on two or more layers
• CPC Class Codes: D21F 11/14 Making cellulose wadding, filter or blotting paper
• CPC Class Codes: Y10T 428/24124 Fibers
• CPC Class Codes: Y10T 428/24446 Wrinkled, creased, crinkled or creped
• CPC Class Codes: Y10T 428/24826 Spot bonds connect components
• CPC Class Codes: Y10T 428/24934 including paper layer

Abstract

Disclosed is a unitary or single-ply fibrous web having a laminate-like structure which consists of a soft, absorbent central core region of relatively low fiber concentration sandwiched between two strong, abrasion-resistant surface regions of higher fiber concentration. The surface regions have bonding material, preferably elastomeric, disposed within to provide strength to the web. The more concentrated fibers in the surface region provide better capillary action to draw moisture into the web. The relatively low fiber concentration within the central core region provides space to increase the amount of moisture absorbable by the web. Within the central core region are networks of fibers connecting the two surface regions together generally without the use of bonding material extending entirely through the web. The bonding material in at least one surface region is disposed in a fine, spaced-apart pattern, and the bonded portions in that surface region are finely creped to soften them. The method of the invention consists of forming a fibrous web, preferably of randomly oriented short fibers, applying to the first side of the web first bonding material which penetrates from about 10 to about 60 percent through the thickness of the finished web product, applying to the second side of the web second bonding material in a fine, spaced-apart pattern which penetrates from about 10 to about 60 percent through the thickness of the finished web product and which does not substantially connect with the first bonding material, adhering the web in a pattern to a creping surface with the second bonding material, and creping the web from the creping surface. The preferred form of the invention consists of applying bonding material in a fine, spaced-apart pattern to one side of the web, pattern adhering that side of the web to the creping surface with the bonding material, and creping the web from the creping surface, and then repeating those steps to the other side of the web.

Claims

1. Fibrous sheet material comprising a single-ply laminate-like web of fibers having a predominate length of less than one-fourth inch, the web having a basis weight of from about 20 to about 100 pounds per ream of 2,880 square feet, the web having an undulating disposition due to creping of the web and having first and second strong, abrasion-resistant, laminate-like surface regions interconnected by a soft, absorbent, laminate-like central core region, the central core region generally having lesS fiber concentration than the surface regions to provide greater bulk, softness and absorbency to the web, each surface region having bonding material disposed throughout to bond the fibers in that surface region together into a strong network, the bonding material in each surface region extending from about 10 percent to about 60 percent through the thickness of the web and being substantially unconnected to the bonding material extending into the web from the other side of the web, the bonding material in the first surface region being disposed in a fine, spaced-apart pattern occupying from about 15 percent to about 60 percent of the surface area of the finished web product on the first surface region side of the web, and the areas in the first surface region where the bonding material is disposed being finely creped.

2. Fibrous sheet material comprising a single-ply laminate-like web of randomly oriented fibers, having a predominate length of less than one-fourth inch, the web having a basis weight of from about 20 to about 100 pounds per ream of 2,880 square feet, and having an undulating disposition due to creping of the web, the web having two strong, abrasion-resistant, laminatelike surface regions interconnected by a soft absorbent, laminatelike central core region, the central core region generally having less fiber concentration than the surface regions to provide greater bulk, softness and absorbency to the web, each surface region having bonding material disposed in a fine spaced apart pattern throughout to bond the fibers in that surface region together into a strong network, the bonding material disposed throughout the surface regions occupying from about 15 percent to about 60 percent of the surface area of the finished web product on each side of the web, and the bonding material being disposed into the web to a depth of from about 10 percent to about 40 percent of the finished web product thickness on each side of the web, and the areas in at least one of the surface regions where the bonding material is disposed being finely creped.

3. Fibrous sheet material recited in claim 2, wherein the bonding material is an elastomeric material and the areas in both of the surface regions where the bonding material has been disposed are finely creped.

4. Fibrous sheet material recited in claim 3, wherein the web is characterized overall by very low interfiber bonding strength except that created by the bonding material in the areas where the bonding material is disposed, and the central core region has split portions generally throughout.

5. Fibrous sheet material recited in claim 4, wherein the web is formed from an aqueous slurry of principally lignocellulosic fibers.

6. Fibrous sheet material as recited in claim 5, wherein the lignocellulosic fibers have been treated with a chemical debonding agent to reduce their interfiber bonding capacity.

7. Fibrous sheet material recited in claim 5, wherein the web has been formed under conditions of reduced pressing until the web was substantially dry to reduce its interfiber bonding strength by reducing the amount of interfiber contact.

8. Fibrous sheet material recited in claim 5, wherein the web has been creped uniformly over the entire surface prior to application of the bonding materials in a fine pattern, whereby interfiber bonds are disrupted and broken by the creping action.

9. Fibrous sheet material as recited in claim 5, wherein all of the fibers are lignocellulosic fibers.

10. Fibrous sheet material recited in claim 5, wherein from about 10% to about 15% of the total fiber mixture comprise relatively long fibers uniformly distributed throughout the web.

11. Fibrous sheet material recited in claim 5, wherein the bonding material disposed in each surface region extends into the web from about 15 percent to about 30 percent of the web thickness.

12. FIbrous sheet material recited in claim 11, wherein the bonding material is disposed in each surface region of the web in a discontinuous intermittent pattern so as to define a pattern of discrete areas having bonding material surrounded by areas having no bonding material.

13. Fibrous sheet material recited in claim 11, wherein the bonding material is disposed in each surface region of the web in a continuous reticular pattern so as to define a discontinuous intermittent pattern of discrete areas having no bonding material surrounded by areas having bonding material.

14. Fibrous sheet material recited in claim 13, wherein the bonding material is disposed in each surface of the web to occupy an area of from about 25 percent to about 50 percent of the surface area of the web.

15. Fibrous sheet material recited in claim 14, wherein the basis weight of the web is from about 25 to about 60 pounds per ream of 2880 square feet.

16. Method of forming a single-ply laminate-like fibrous web, comprising the steps of:

a. providing a fibrous web of fibers having a predominate length of less than one-fourth inch and having a basis weight of from about 16 to about 80 pounds per ream of 2,880 square feet;

b. applying to the first side of the web a first bonding material which penetrates from about 10 percent to about 60 percent through the thickness of the finished web product and forms bonded web portions in which fibers are bonded together by the bonding material to form a strong, abrasion-resistant laminate-like surface region;

c. applying to the second side of the web a second bonding material in a fine, spaced-apart pattern arrangement which covers between about 15 percent and about 60 percent of the surface area of the second side of the finished web product and penetrates from about 10 percent to about 60 percent through the thickness of the finished web product and which does not substantially interconnect with the first bonding material and which forms bonded web portions in which fibers are bonded together by the bonding material to form a strong, abrasion-resistant, laminate-like surface region;

d. adhering the bonded portions of the second surface of the web to a creping surface by use of the second bonding material; and

e. creping the web from the creping surface.

17. Method of forming a single-ply laminate-like fibrous web comprising the steps of:

a. providing a web having a basis weight of from about 16 to about 80 pounds per ream of 2880 square feet of randomly oriented fibers having a predominent length of less than one-fourth inch;

b. applying to the first side of the web first bonding material in a fine spaced-apart pattern arrangement which covers between about 15 percent and about 60 percent of the surface area of the finished web product and penetrates into the web to a depth of from about 10 percent to about 40 percent of the thickness of the finished web product and which forms bonded web portions in which fibers are bonded together by the bonding material to form a strong, abrasion-resistant, laminate-like surface region;

c. applying to the second side of the web a second bonding material in a fine spaced-apart pattern arrangement which covers from about 15 percent to about 60 percent of the surface area of the finished web product and penetrates into the web to a depth of from about 10 percent to about 40 percent of the thickness of the finished web product and which forms bonded web portions in which fibers are bonded together by the bonding material to form a strong, abrasion-resistant, laminate-like surface region;

d. adhering by use of the bonding material the areas on one side of the web where the bonding material has been disposed to a first creping surface; and

e. creping the web from the creping surface.

18. The method recited in claim 17, wheRein step (a) comprises forming the web under conditions resulting in very low interfiber bonding strength and the bonding material is characterized as an elastomeric material.

19. Method recited in claim 18, wherein steps (d) and (e) are performed before step (c).

20. Method as recited in claim 19, including the steps of:

f. adhering by use of the bonding material the areas on the second side of the web where the bonding material has been disposed to a creping surface; and

g. creping the web from the creping surface.

21. Method as recited in claim 20, wherein the web is formed from an aqueous slurry of principally lignocellulosic fibers.

22. Method as recited in claim 21, including the step of treating the lignocellulosic fibers with a chemical debonding agent prior to drying the web to reduce their interfiber bonding capacity.

23. Method as recited in claim 21, including the step of forming the web under conditions of reduced pressing until it is substantially dry, whereby the amount of interfiber contact and interfiber bonding strength is reduced.

24. Method as recited in claim 21, including the step of creping the web over its entire surface prior to step (b) so as to disrupt and break interfiber bonds by the creping action.

25. Method recited in claim 21, wherein the web is formed from all lignocellulosic fibers.

26. Method recited in claim 21, wherein the web includes from 10 percent to 15 percent relatively long fibers.

27. Method recited in claim 21, wherein the bonding material applied to each side of the web penetrates into the web from about 15 percent to about 30 percent of the thickness of the finished web product.

28. Method recited in claim 27, wherein the bonding material is applied to both sides of the web in a discontinuous intermittent pattern so as to define a pattern of discrete areas having bonding materials surrounded by areas having no bonding material.

29. Method recited in claim 27, wherein the bonding material is applied to both sides of the web in a continuous reticular pattern so as to define a discontinuous intermittent pattern of discrete areas having no bonding materials surrounded by areas having bonding material.

30. Method recited in claim 29, wherein the bonding material is applied to each side of the web in a pattern which causes the bonding material to occupy from about 25 percent to about 50 percent of the finished web product surface area on each side.

31. Method recited in claim 30, wherein the basis weight of the web formed in step (a) is from about 22 to about 45 pounds per ream of 2880 square feet.

32. Fibrous sheet material recited in claim 1, wherein the sheet material has a basis weight of from about 20 to 100 pounds per ream of 2880 square feet.

33. Fibrous sheet material recited in claim 2, wherein the total bonding material disposed in both surface regions is from about 3 percent to about 20 percent of the dry fiber weight of the finished web product.