HIGH CELLULOSE CONTENT, LAMINIFEROUS NONWOVEN FABRIC

• US 20120177888A1
• Filed: 07/20/2010
• Published: 07/12/2012
• Est. Priority Date: 07/20/2009
• Status: Active Grant

• Current Assignee: Suominen Corporation
• Original Assignee: Ahlstrom Corporation
• Inventors: Escafere, Pascale, Meikle, Gordon, Nortman, Brian
• Granted Patent: US 9,296,176 B2
• Time in Patent Office: Days
• US Class Current: 428/162
• CPC Class Codes: B32B 2250/20 All layers being fibrous or filamentary
• CPC Class Codes: B32B 2262/02 Synthetic macromolecular fibres
• CPC Class Codes: B32B 2262/0253 Polyolefin fibres
• CPC Class Codes: B32B 2262/0276 Polyester fibres
• CPC Class Codes: B32B 2262/062 Cellulose fibres, e.g. cotton
• CPC Class Codes: B32B 2262/12 Conjugate fibres, e.g. core/sheath or side-by-side
• CPC Class Codes: B32B 2262/14 Mixture of at least two fibres made of different materials
• CPC Class Codes: B32B 23/02 in the form of fibres or filaments not used
• CPC Class Codes: B32B 2305/20 in the form of a non-woven mat
• CPC Class Codes: B32B 2307/54 Yield strength; Tensile strength
• CPC Class Codes: B32B 2307/554 Wear resistance
• CPC Class Codes: B32B 2307/718 Weight, e.g. weight per square meter
• CPC Class Codes: B32B 2307/726 Permeability to liquids, absorption
• CPC Class Codes: B32B 2317/18 Cellulose, modified cellulose or cellulose derivatives, e.g. viscose B32B2317/10, B32B2317/12, B32B2317/16 take precedence
• CPC Class Codes: B32B 2432/00 Cleaning articles, e.g. mops or wipes
• CPC Class Codes: B32B 2555/00 Personal care
• CPC Class Codes: B32B 37/0084 Point bonding
• CPC Class Codes: B32B 37/12 characterised by using adhesives
• CPC Class Codes: B32B 38/06 Embossing
• CPC Class Codes: B32B 5/022 Non-woven fabric
• CPC Class Codes: B32B 5/06 : characterised by a fibrous or filamentary layer mechanically connected, e.g. by needling to another layer, e.g. of fibres, of paper
• CPC Class Codes: B32B 5/08 : the fibres or filaments of a layer being of different substances , e.g. conjugate fibres, mixture of different fibres
• CPC Class Codes: B32B 5/145 : Variation across the thickness of the layer
• CPC Class Codes: B32B 5/22 : characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed layer formed of natural mineral fibres or particles next to a foam layer B32B19/047, next to a layer made of particles B32B19/048, or next to a fibrous or filamentary layer B32B19/06; paper layer or cardboard layer next to a paper layer or cardboard layer B32B29/005, next to a foam layer B32B29/007, next to a fibrous or filamentary layer B32B29/02, or next to a particulate layer B32B29/04
• CPC Class Codes: B32B 5/26 : another layer next to it also being fibrous or filamentary relative arrangement of fibres or filaments of different layers B32B5/12
• CPC Class Codes: B32B 7/12 : using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: D04H 1/425 : Cellulose series
• CPC Class Codes: D04H 1/559 : the fibres being within layered webs
• CPC Class Codes: D04H 1/56 : in association with fibre formation, e.g. immediately following extrusion of staple fibres
• CPC Class Codes: D04H 1/732 : by fluid current, e.g. air-lay
• CPC Class Codes: Y10T 428/24529 : and conforming component on an opposite nonplanar surface
• CPC Class Codes: Y10T 428/24942 : including components having same physical characteristic in differing degree

Abstract

The present invention provides a laminiferous nonwoven fabric with a high woodpulp content suitable for use in wipes, absorbent articles and other applications, and a method of making the same. The laminiferous nonwoven comprises 3 layers bonded together, where the outer layers are lightweight meltspun webs and the middle layer comprises mainly woodpulp fibres. Each of the first (3), second (2) and third (4) nonwoven layer are preferably first formed separately and individually to be self-supported webs, whereafter the three self-supported webs are brought together essentially immediately before bonding them together. When used as a substrate for wet wipes, the inventive fabric exhibits a combination of several useful properties; good wet and dry softness and bulk, good wet abrasion resistance and low wet linting propensity, and where the majority raw material is woodpulp.

Claims

1-31. -31. (canceled)

32. A method for manufacturing laminiferous nonwoven fabrics,

providing at least a first nonwoven layer, consisting essentially of natural cellulose fibres and thermoplastic fibres, and

applying on both sides of said first layer, a second and a third nonwoven layer, which second and third nonwoven layers consist essentially of melt-spinnable fibres and each second and third nonwoven layer having a basis weight of 12 gsm or less and,

wherein

at least one of the second or third nonwoven layers is formed separately and individually to be a self-supporting web with a geometric mean wet tensile strength/basis weight ratio of at least 7 N/m per gsm,

the nonwoven fabric comprises at least 50% by weight cellulose,

the first layer is formed by air forming process, and

the three webs are bonded using ultrasonic, thermal or adhesive bonding.

33. The method of claim 32, wherein both the second and the third nonwoven layers have a basis weight of 12 gsm or less.

34. The method of claim 32, wherein the cellulose fiber content of the nonwoven fabric is at least 65%.

35. The method of claim 32 wherein at least one of the second or third nonwoven layers are manufactured by a high strength meltblown process.

36. The method of claim 32, wherein the three nonwoven layers are produced separately in such a way that the boundary between any two adjacent nonwoven layers is distinct in that the fibres at or near the surfaces of such adjacent layers are not significantly intermingled.

37. The method of claim 32, wherein the basis weight of the laminiferous nonwoven fabric is less than 200 gsm.

38. The method of claim 32, wherein the nonwoven fabric in the first nonwoven layer comprises more than 75% w/w of cellulose fibres and less than 25% w/w of thermoplastic material.

39. The of claim 32, wherein both the second and third nonwoven layer is separately and individually formed to be self-supporting webs, afterwhich the three webs are brought together essentially immediately before bonding them together to form the composite nonwoven fabric.

40. The method of claim 32, wherein the fabric comprises in each first, second and third layer the same melt-spinnable material.

41. The method of claim 32, wherein the first layer is formed by a coform method.

42. The method of claim 32, wherein the first nonwoven layer is patterned before the three webs are brought together.

43. The method of claim 32, wherein the first, second and third nonwoven layer are bonded together thermally, ultrasonically or by glueing to form a laminiferous nonwoven fabric and wherein the boundary between any two adjacent nonwoven layers is distinct in that fibres at or near the surfaces of such adjacent layers are not significantly intermingled.

44. The method of claim 32, wherein the first layer is formed as an essentially homogenous monolayer.

45. The method of claim 32, wherein the first layer is formed as a stratified or layered structure, in which thermoplastic material e.g. fibres are concentrated near top and bottom surfaces of the first nonwoven layer.

46. A laminiferous nonwoven fabric, comprising:

at least a first nonwoven layer, consisting essentially of natural cellulose fibres and thermoplastic fibres,

on both sides of said first layer, a second and a third nonwoven layer, which second and third nonwoven layers consist essentially of melt-spinnable fibres and each second and third nonwoven layer having a basis weight of 12 gsm or less, wherein

the first layer is formed by air forming process,

at least one of the second or third nonwoven layers is formed separately and individually to be a self-supporting web with a geometric mean wet tensile strength/basis weight ratio of at least 7 N/m per gsm,

the nonwoven fabric comprises at least 50% by weight cellulose, and

the three webs are bonded together using ultrasonic, thermal or adhesive bonding.

47. The fabric of claim 46, wherein the fabric has a wet bulk of 7.5 cc/gram or higher.

48. The fabric of claim 46, wherein the fibres of the first nonwoven layer are shortcut fibres.

49. The fabric of claim 46, wherein the Wet Martindale abrasion resistance of the high cellulose content composite nonwoven fabric is better than 10 rubs, preferably better than 20 rubs, most preferably better than 30 rubs.

50. The fabric of claim 46, wherein both the second and the third nonwoven layers have a basis weight of 12 gsm or less.

51. The fabric of claim 46, wherein both the second and the third nonwoven layers are manufactured with a high strength meltblown process.

52. The fabric of claim 46, wherein the first, second and third nonwoven layer are thermally, ultrasonically or by glueing bonded together to form a laminiferous nonwoven fabric (1) and that the boundary between any two adjacent nonwoven layers is distinct in that fibres at or near the surfaces of such adjacent layers are not significantly intermingled.

53. The fabric of claim 46, wherein the basis weight of the laminiferous nonwoven fabric is less than 200 gsm.

54. The fabric of claim 46, wherein the first nonwoven layer comprise more than 75% w/w of cellulose fibres and less than 25% w/w of thermoplastic material.

55. The fabric of claim 46, wherein first, second and third layer comprise the same melt-spinnable material.

56. The fabric of claim 46, wherein the laminiferous nonwoven fabric has the absorption capacity of more than 900% by wt.

57. The fabric of claim 46, wherein the nonwoven fabric comprises at least 65% w/w cellulose fibres.

58. The fabric of claim 46, wherein the wet lint value of the fabric as measured by the gravimetric method is 35 ppm or less.

59. The fabric of claim 46, wherein the dry basis weight of the composite nonwoven fabric is between 40 gsm and 65 gsm and the outer nonwoven layers, each being a high strength meltblown polypropylene nonwoven web of about 6 gsm or less, the first nonwoven layer, being an airformed nonwoven web comprising a blend of debonded fluff pulp, and

shortcut polypropylene fibres or a mixture of shortcut polypropylene fibres and shortcut polyethylene sheath/polypropylene core bicomponent fibres,

the amount of debonded fluff pulp comprising between 70 to 90% w/w in the first nonwoven layer and wherein the three layers are bonded together by thermal or ultrasonic point-bonding and wherein the boundary between any two adjacent nonwoven layers is distinct in that fibres at or near the surfaces of such adjacent layers are not significantly intermingled.

60. The fabric of claim 46, wherein the first nonwoven layer is patterned before the three webs are brought together.

61. The fabric of claim 46, wherein the first layer is an essentially homogenous monolayer.

62. The fabric of claim 46, wherein the first layer is a stratified or layered structure, wherein thermoplastic materials are concentrated near top and bottom surfaces of the first nonwoven layer.