CA2973728C

Glue-bonded multi-ply absorbent sheet and polyvinyl alcohol ply bonding adhesive

Abstract

A multi-ply absorbent sheet includes a first absorbent ply of cellulosic sheet; a second absorbent ply of cellulosic sheet; and a ply bonding adhesive interposed between the first absorbent ply and the second absorbent ply, the ply-bonding adhesive thereby adhering said absorbent plies together. The ply-bonding adhesive comprises polyvinyl alcohol and nanofibrillated cellulose. In a particularly preferred embodiment the adhesive is applied as a dilute aqueous composition to tissue plies and the nanofibrillated cellulose has a Characteristic Breaking Length of 6.5 km or above.

CA2973728C, drawing sheet 1
Sheet 1 of 26

Term

9.3 yearsleft in the term

Expires 21 January 2036.

  1. Priority
  2. Filed
  3. Granted
  4. Today
  5. Expires

39 claims: 4 independent, 35 dependent

  1. 1
    CA 2,973,728 CPST Ref:14818/00517 WHAT IS CLAIMED IS: 1. A ply bonding adhesive composition for the manufacture of multi-ply paper tissue and multi-ply paper towel comprising: (a) water;(b) polyvinyl alcohol;and (c) nanofibrillated cellulose;wherein the adhesive comprises from 90-98.5% by weight of the composition water, at least 0.5% by weight of the composition polyvinyl alcohol and from 0.05% to 2.5% by weight of the composition nanofibrillated cellulose and wherein said nanofibrillated cellulose is characterized in that: (i) the nanofibrillated cellulose contains fibrils 4-20 nm wide and 500-2000 nm long;or (ii) the nanofibrillated cellulose exhibits a Characteristic Nanofiber Viscosity Reduction of at least 80% as the shear rate is increased from 5 sec 1 to 500 sec 1 , the viscosity being measured on a 1 wt% suspension of the nanofibrillated cellulose in water at room temperature, between 23°C and 29°C.
  2. 2
    The ply bonding adhesive composition according to Claim 1, wherein the adhesive comprises from 90-98.5% by weight of the composition water, from 0.5% to 6% by weight of the composition polyvinyl alcohol and from 0.25% to 2.5% by weight of the composition nanofibrillated cellulose.
  3. 3
    The ply bonding adhesive composition according to Claim 1 or 2, wherein said nanofibrillated cellulose has a Characteristic Breaking Length of at least 3 km.
  4. 4
    The ply bonding adhesive composition according to any one of Claims 1 to 3, wherein said nanofibrillated cellulose has a Characteristic Breaking Length of from 4.5 km to 9 km.
  5. 5
    The ply bonding adhesive composition according to any one of Claims 1 to 4, wherein the weight ratio of nanofibrillated cellulose:polyvinyl alcohol is greater than 0.025 and up to 2. 1395-9756-6982, v. 4 Date Reçue/Date Received 2023-12-18 CA 2,973,728 CPST Ref: 14818/00517
  6. 6
    The ply bonding adhesive composition according to any one of Claims 1 to 5, wherein the weight ratio of nanofibrillated cellulose:polyvinyl alcohol is greater than 0.25 and up to 2.
  7. 7
    The ply bonding adhesive composition according to any one of Claims 1 to 6, wherein the nanofibrillated cellulose is present in an amount of greater than 0.4 percent by weight based on the weight of the aqueous composition and up to 1.5 percent by weight based on the weight of the aqueous composition.
  8. 8
    The ply bonding adhesive composition according to any one of Claims 1 to 7, wherein the adhesive contains from 0.5% by weight to 50% by weight of the nanofibrillated cellulose, based on the weight of polyvinyl alcohol.
  9. 9
    The ply bonding adhesive composition according to any one of Claims 1 to 8, wherein the adhesive contains from 1% by weight to 30% by weight of the nanofibrillated cellulose, based on the weight of polyvinyl alcohol.
  10. 10
    The ply bonding adhesive composition according to any one of Claims 1 to 9, wherein the adhesive contains from 1.5 % by weight to 20% by weight of the nanofibrillated cellulose, based on the weight of polyvinyl alcohol.
  11. 11
    The ply bonding adhesive composition according to any one of Claims 1 to 8, comprising polyvinyl alcohol in an amount of at least 1.5% by weight based on the weight of the adhesive composition;and from 1% to 50% by weight of the nanofibrillated cellulose based on the weight of polyvinyl alcohol in the adhesive.
  12. 12
    The ply bonding adhesive composition according to Claim 11, wherein the adhesive comprises from 90-98.5% by weight of the composition water, from 1.5% to 6% by weight of the composition polyvinyl alcohol and from 1% to 30% by weight of the nanofibrillated cellulose based on the weight of polyvinyl alcohol in the adhesive. 1395-9756-6982, v. 4 Date Reçue/Date Received 2023-12-18 CA 2,973,728 CPST Ref:14818/00517
  13. 13
    The ply bonding adhesive composition according to Claim 12, wherein the adhesive comprises from 94-98.5% by weight of the composition water, at least 1.5% by weight of the composition polyvinyl alcohol and from 1% to 30% by weight of the nanofibrillated cellulose based on the weight of polyvinyl alcohol in the adhesive.
  14. 14
    The ply bonding adhesive composition according to Claim 1, consisting of water, polyvinyl alcohol in an amount of from 1.5% to 6% by weight based on the weight of the adhesive composition;and from 1% to 50% by weight of the nanofibrillated cellulose based on the weight of polyvinyl alcohol in the adhesive and wherein the adhesive exhibits an Adhesive Viscosity reduction of at least 15% as shear rate is increased from 1 sec -1 to 100 sec 1 .
  15. 15
    A multi-ply absorbent sheet comprising:(a) a first absorbent ply of cellulosic sheet;(b) a second absorbent ply of cellulosic sheet;and (c) a ply bonding adhesive interposed between said first absorbent ply and said second absorbent ply, said ply-bonding adhesive adhering said absorbent plies together, wherein said first absorbent ply of cellulosic sheet and said second absorbent ply of absorbent sheet are adhered together utilizing the ply-bonding adhesive composition of any one of Claims 1 to 14.
  16. 16
    The multi-ply absorbent sheet according to Claim 15, wherein the multi-ply sheet further comprises a third absorbent ply of cellulosic sheet plied together with the first and second ply.
  17. 17
    The multi-ply absorbent sheet according to Claim 16, consisting of three plies laminated together, wherein the ply bonding adhesive is applied only between two plies prior to lamination.
  18. 18
    A method of making an absorbent sheet comprising:(a) providing a first absorbent cellulosic basesheet;(b) applying a ply bonding adhesive composition containing polyvinyl alcohol and nanofibrillated cellulose according to any one of Claims 1 to 14 to said first cellulosic basesheet;and 1395-9756-6982, v. 4 Date Reçue/Date Received 2023-12-18 CA 2,973,728 CPST Ref: 14818/00517 (c) plying a second absorbent cellulosic basesheet with said first cellulosic basesheet by pressing said second cellulosic basesheet to the ply bonding adhesive composition disposed on said first cellulosic basesheet.
  19. 19
    A method of making an absorbent sheet, comprising:(a) feeding a first absorbent cellulosic basesheet to an embossing nip;(b) embossing a pattern of raised embossments in said first cellulosic basesheet;(c) applying a ply bonding adhesive composition containing polyvinyl alcohol and nanofibrillated cellulose according to any one of Claims 1 to 14 to the raised embossments of said first cellulosic basesheet;and (d) plying a second absorbent cellulosic basesheet with said first cellulosic basesheet by pressing said second cellulosic basesheet to the ply bonding adhesive composition disposed on the raised embossments of said first cellulosic basesheet.
  20. 20
    A method of making a multi-ply absorbent sheet comprising:(a) providing a first absorbent cellulosic basesheet;(b) providing a second absorbent cellulosic basesheet;(c) interposing an aqueous adhesive containing polyvinyl alcohol and nanofibrillated cellulose between said first and second cellulosic basesheets;and (d) plying said first absorbent cellulosic basesheet with said second absorbent cellulosic basesheet by pressing said absorbent cellulosic basesheets together to make the multi-ply absorbent sheet and wherein said nanofibrillated cellulose is characterized in that: (i) the nanofibrillated cellulose contains fibrils 4-20 nm wide and 500-2000 nm long;or (ii) the nanofibrillated cellulose exhibits a Characteristic Nanofiber Viscosity Reduction of at least 80% as the shear rate is increased from 5 sec 1 to 500 sec 1 , the viscosity being measured on a 1 wt% suspension of the nanofibrillated cellulose in water at room temperature, between 23°C and 29°C.
  21. 21
    The method of making the multi-ply absorbent sheet according to Claim 20, wherein said nanofibrillated cellulose has a Characteristic Nanofiber Viscosity of greater than 200,000 cP at a 64 1395-9756-6982, v. 4 Date Reçue/Date Received 2023-12-18 CA 2,973,728 CPST Ref:14818/00517 shear rate of 1 sec -1 and a Characteristic Nanofiber Viscosity of less than 50,000 cP at a shear rate of 50 sec 1 .
  22. 22
    The method of making the multi-ply absorbent sheet according to Claim 20, wherein said nanofibrillated cellulose has a Characteristic Nanofiber Viscosity of greater than 350 cP at a shear rate of 1 sec 1 and a Characteristic Nanofiber Viscosity of less than 50 cP at a shear rate of 50 sec 1 .
  23. 23
    The method of making the multi-ply absorbent sheet according to Claim 20, wherein said nanofibrillated cellulose has a Characteristic Nanofiber Viscosity of greater than 4,000 cP at a shear rate of 1 sec 1 and a Characteristic Viscosity of less than 1,500 cP at a shear rate of 50 sec 1 .
  24. 24
    The method of making the multi-ply absorbent sheet according to Claim 20, wherein said nanofibrillated cellulose has a Characteristic Nanofiber Viscosity of greater than 15,000 cP at a shear rate of 5 sec 1 and a Characteristic Nanofiber Viscosity of less than 2,000 cP at a shear rate of 500 sec 1 .
  25. 25
    The method of making the multi-ply absorbent sheet according to any one of Claims 20 to 24, wherein the adhesive contains from 0.5% by weight to 20% by weight of nanofibrillated cellulose, based on the weight of polyvinyl alcohol.
  26. 26
    The method of making the multi-ply absorbent sheet according to any one of Claims 20 to 24, wherein the adhesive contains from 0.5% by weight to 30% by weight of nanofibrillated cellulose, based on the weight of polyvinyl alcohol.
  27. 27
    The method of making the multi-ply absorbent sheet according to any one of Claims 20 to 24, wherein the adhesive contains from 0.5% by weight to 40% by weight of nanofibrillated cellulose, based on the weight of polyvinyl alcohol. 1395-9756-6982, v. 4 Date Reçue/Date Received 2023-12-18 CA 2,973,728 CPST Ref:14818/00517
  28. 28
    The method of making the multi-ply absorbent sheet according to any one of Claims 20 to 24, wherein the adhesive contains from 0.5% by weight to 50% by weight of nanofibrillated cellulose, based on the weight of polyvinyl alcohol.
  29. 29
    The method of making the multi-ply absorbent sheet according to any one of Claims 20 to 24, wherein the adhesive contains from 1% by weight to 6% by weight of nanofibrillated cellulose, based on the weight of polyvinyl alcohol.
  30. 30
    A ply bonding adhesive for the manufacture of multi-ply paper tissue and multi-ply paper towel comprising:(a) water in an amount of from 90-98.5% by weight of the adhesive composition;(b) polyvinyl alcohol in an amount of at least 1.5% by weight based on the weight of the adhesive composition;and (c) from 1% to 50% by weight of nanofibrillated cellulose based on the weight of polyvinyl alcohol in the adhesive composition and wherein said nanofibrillated cellulose is characterized in that: (i) the nanofibrillated cellulose contains fibrils 4-20 nm wide and 500-2000 nm long;or (ii) the nanofibrillated cellulose exhibits a Characteristic Nanofiber Viscosity Reduction of at least 80% as the shear rate is increased from 5 sec -1 to 500 sec 1 , the viscosity being measured on a 1 wt% suspension of the nanofibrillated cellulose in water at room temperature, between 23°C and 29°C.
  31. 31
    The ply bonding adhesive according to Claim 30, wherein the adhesive comprises from 1.5% to 6% by weight of the composition polyvinyl alcohol and from 1% to 20% by weight of nanofibrillated cellulose based on the weight of polyvinyl alcohol in the adhesive.
  32. 32
    The ply bonding adhesive according to Claim 30, wherein the adhesive comprises from 1.5% to 6% by weight of the composition polyvinyl alcohol and from 1% to 40% by weight of nanofibrillated cellulose based on the weight of polyvinyl alcohol in the adhesive. 1395-9756-6982, v. 4 Date Reçue/Date Received 2023-12-18 CA 2,973,728 CPST Ref:14818/00517
  33. 33
    The ply bonding adhesive according to Claim 30, wherein the adhesive comprises from 1.5% to 6% by weight of the composition polyvinyl alcohol and from 1% to 50% by weight of nanofibrillated cellulose based on the weight of polyvinyl alcohol in the adhesive.
  34. 34
    The ply bonding adhesive according to any one of Claims 30 to 33, wherein the adhesive is for application between plies of a multi-ply absorbent sheet as an aqueous composition containing from 1.5% to 3% by weight of the composition polyvinyl alcohol.
  35. 35
    The ply bonding adhesive according to any one of Claims 30 to 34, wherein said nanofibrillated cellulose has a Characteristic Nanofiber Viscosity of greater than 200,000 cP at a shear rate of 1 sec 1 and a Characteristic Nanofiber Viscosity of less than 50,000 cP at a shear rate of 50 sec 1 .
  36. 36
    The ply bonding adhesive according to any one of Claims 30 to 34, wherein said nanofibrillated cellulose has a Characteristic Nanofiber Viscosity of greater than 350 cP at a shear rate of 1 sec 1 and a Characteristic Nanofiber Viscosity of less than 50 cP at a shear rate of 50 sec 1 .
  37. 37
    The ply bonding adhesive according to any one of Claims 30 to 34, wherein said nanofibrillated cellulose has a Characteristic Nanofiber Viscosity of greater than 4,000 cP at a shear rate of 1 sec 1 and a Characteristic Nanofiber Viscosity of less than 1,500 cP at a shear rate of 50 sec 1 .
  38. 38
    The ply bonding adhesive according to any one of Claims 30 to 37, wherein said nanofibrillated cellulose has a Characteristic Breaking Length of from 4.5 km to 9 km.
  39. 39
    The ply bonding adhesive according to any one of Claims 30 to 38, wherein the polyvinyl alcohol in the adhesive has a Characteristic PVOH Viscosity of from 3 to 75 cP. 1395-9756-6982, v. 4 Date Reçue/Date Received 2023-12-18
Independent claims39