NONWOVEN FABRIC AND METHOD OF FABRICATION THEREOF

Abstract

There is disclosed a nonwoven fabric. The nonwoven fabric may comprise short fibers of plant-based material having a length of about between 2 mm and 5 mm, and cellulose filaments being present at a proportion of up to 10 wt-% of the nonwoven fabric, such that the cellulose filaments bind the short fibers in the nonwoven fabric. Long fibers are optionally added to the nonwoven fabric.

Claims

1-41. (canceled)

42. A method for producing a nonwoven fabric, the method comprising: providing a liquid suspension of never-dry pulp; forming a web from the provided liquid suspension; dewatering the web; entangling the web to obtain a wet fabric; and drying the wet fabric; wherein the dried fabric has at least one of: a machine-direction dry tensile strength of at least 45 N/50 mm; a machine-direction wet tensile strength of at least 9 N/50 mm; a cross-machine-direction dry tensile strength of at least 25 N/50 mm; and a cross-machine-direction wet tensile strength of at least 6 N/50 mm.

43. The method according to claim 42, wherein the liquid suspension comprises at least one of cellulose filaments and long fibers.

44. The method according to claim 43, wherein at least one of: the long fibers have a length of at least 5 mm; the long fibers are present at a proportion of up to 40 wt-% of the nonwoven fabric; and the long fibers are selected from the group consisting of man-made fibers, regenerated cellulose and a mixture thereof.

45. The method according to claim 43, wherein the liquid suspension comprises cellulose filaments at a proportion of up to 10 wt-% of the nonwoven fabric.

46. The method according to claim 42, wherein at least one of: the never-dry pulp comprises short fibers having a length between about 2 mm and about 5 mm; and the never-dry pulp is derived from a raw material selected from the group consisting of wood, hemp, bamboo, bagasse, flax, natural plant fibers, cotton and mixtures thereof.

47. The method according to claim 42, wherein at least one of: the forming the web comprises wet-laying the liquid suspension; and the entangling comprises hydroentangling.

48. A nonwoven fabric produced according to the method of claim 42.

49. The nonwoven fabric according to claim 48, wherein the fabric is IWSFG Slosh Box flushable.

50. A nonwoven fabric comprising: short fibers of plant-based material having a length between about 2 mm and about 5 mm; and cellulose filaments being present at a proportion of up to 10 wt-% of the nonwoven fabric, such that the cellulose filaments bind the short fibers in the nonwoven fabric.

51. The nonwoven fabric according to claim 50, further comprising long fibers having a length of more than 5 mm, the long fibers being present at a proportion of up to 40 wt-% of the nonwoven fabric, such that the cellulose filaments bind the long fibers in the nonwoven fabric.

52. The nonwoven fabric according to claim 50, wherein at least one of: the proportion of cellulose filaments is between 2 wt-% and 7 wt-%; and the short fibers are derived from a raw material selected from the group consisting of wood pulp, hemp, bamboo, bagasse, flax, natural plant fibers, cotton and a mixture thereof.

53. The nonwoven fabric according to claim 51, wherein at least one of: the proportion of long fibers is up to 20 wt-%; the long fibers are selected from the group consisting of man-made fibers, regenerated cellulose and a mixture thereof; and the long fibers are selected from the group consisting of cotton, hemp, jute, flax and a mixture thereof.

54. The nonwoven fabric according to claim 50, wherein the fabric is a wet wipe in a liquid phase comprising at least one of an alcohol and a lotion.

55. The nonwoven fabric according to claim 54, wherein at least one of: the liquid phase comprises an alcohol and has an alcohol content between 20 vol % and 80 vol %; and the liquid phase comprises a water-based lotion.

56. The nonwoven fabric according to claim 50, wherein at least one of: the nonwoven fabric has a basis weight of about 40 GSM to about 85 GSM; the nonwoven fabric has a dry tensile strength of at least 31 N/50 mm and a wet tensile strength of at least 6.4 N/50 mm; the nonwoven fabric has a dry maximal elongation of at least 7% and a wet maximal elongation of at least 26%; the nonwoven fabric has a water absorptive capacity of at least 4.2 g/g; the nonwoven fabric has a liquid wicking rate of at least 43 mm/30 sec; the nonwoven fabric has a disintegration rate of at least 60% as measured according to IWSFG Slosh Box standards; the nonwoven fabric has an opacity of at least about 50%; and the nonwoven fabric has a dry linting rate of 0.01% and a degradation rate of 2.14%.

57. A method for fabricating a nonwoven fabric, the method comprising: preparing a liquid suspension of: short fibers having a length between about 2 mm and about 5 mm; and cellulose filaments being present at a proportion of up to 10 wt-% of the nonwoven fabric; forming a web from the prepared liquid suspension and dewatering the web; hydroentangling the web to obtain a wet fabric; and drying the wet fabric to obtain a dried fabric.

58. The method according to claim 57, wherein the liquid suspension comprises long fibers having a length of more than 5 mm, the long fibers being present at a proportion of up to 40 wt-% of the nonwoven fabric.

59. The method according to claim 57, wherein said forming the web comprises wet-laying the liquid suspension.

60. The method according to claim 57, further comprising at least one of: patterning the wet fabric; calendering the dried fabric; embossing the dried fabric; and winding the dried fabric thereby obtaining a roll of fabric.

61. A wetlaid fabric product comprising: wood pulp short fibers having a length of about between 2 mm and 5 mm; and cellulose filaments being present at a proportion of up to 10 wt-% of the wetlaid fabric, such that the cellulose filaments bind the short fibers in the nonwoven fabric.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Having thus generally described the nature of the invention, reference will now be made to the accompanying drawings, showing by way of illustration example embodiments thereof and in which:

[0055] FIG. 1 represents an electron microscope image of the fiber structure of a nonwoven fabric according to one embodiment of the invention;

[0056] FIG. 2 represents an electron microscope image of the fiber structure of a nonwoven fabric comprising cellulose filaments according to one embodiment of the invention;

[0057] FIG. 3 represents a schematic view of a system for fabricating a nonwoven fabric according to one embodiment of the invention; and

[0058] FIG. 4 represents a flowchart that illustrates a method for fabricating a nonwoven fabric according to one embodiment of the invention.

[0059] FIG. 5 represents a method of producing a nonwoven fabric according to one embodiment.

[0060] FIG. 6 represents the characteristic strengths of nonwoven fabric samples according to an embodiment.

[0061] FIG. 7 represents the characteristic strains of nonwoven fabric samples according to an embodiment.

[0062] FIG. 8 represents the Weibull fit of nonwoven fabric samples according to an embodiment.

[0063] FIG. 9 represents the Weibull modulus of nonwoven fabric samples according to an embodiment

[0064] FIGS. 10A and 10B represent the tensile strengths of nonwoven fabric samples comprising never-dry and market pulp according to an embodiment.

[0065] FIGS. 11A and 11B represent the tensile strengths of nonwoven fabric samples comprising 0% and 5% CF according to an embodiment.

[0066] FIGS. 12A and 12B represent dry linting and dusting test results on samples of nonwoven fabrics according to an embodiment.

[0067] FIG. 13 represents dry linting and dusting test results on samples of nonwoven fabrics according to an embodiment.

[0068] FIG. 14 represents wet linting and dusting test results on samples of nonwoven fabrics according to an embodiment.

[0069] FIGS. 15A, 15B, 15C and 15D represents dry and wet linting results on samples of nonwoven fabrics comprising 0% CF and 5% CF according to an embodiment.

[0070] FIGS. 16A and 16B provide a magnified view of portions of FIGS. 15A and 15B respectively.

[0071] FIG. 17 represents exemplary degraded nonwoven fabric samples according to an embodiment and corresponding degradation scores.

[0072] FIG. 18 represents dry degradation test results on samples of nonwoven fabric according to an embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

[0073] In the following description of the embodiments, references to the accompanying drawings are by way of illustration of an example by which one or more embodiments of the invention may be practiced.

[0074] The term MD and CD means machine-direction and cross-machine direction, respectively.

[0075] The term wet-laying or wet-laid refer to a method for depositing a liquid suspension to form a web.

[0076] The terms never-dried pulp, never-dry pulp and wet-lap refer to pulp that has not been dried prior to use, and processes comprising the same.

[0077] The terms market pulp and dry-lap refer to conventional pulp that has been dried prior to use, and processes comprising the same.

[0078] The term hydroentangling or hydroentanglement refer to a method for intertwining fiber in a web using water jets.

[0079] The term hydroembossing refers a method of patterning a surface by spraying waters jets on sheet in contact with a patterned drum.

[0080] The term biodegradable refers to a composition of matter is capable of being decomposed by bacteria or other living organisms within a reasonable period.

[0081] The term plastic-free refers to a composition of matter that contains essentially no amount of synthetic polymer(s) or any other non-naturally occurring polymer, but may contain cellulose-based fiber and/or regenerated cellulose, for example viscose, rayon, acetate, triacetate, modal, Tencel, and Lyocell.

[0082] The term long fiber and long cellulose fiber refers to fiber whose composition, structure and properties were significantly modified in a given process. Generally, long fiber and long cellulose fiber do not contain synthetic plastic fiber and cellulose filament and have a length of more than 5 mm.

[0083] The expressions short fiber and short cellulose fiber refer to fibers composed of a polymer matrix, typically glucose, that is derived from a plant-based material through mechanical and/or chemical process. Generally, short fiber and short cellulose fiber have a length of between 2 mm and 5 mm.

[0084] The expression cellulose filaments when used herein relates to plant based fibers treated to achieve a high aspect ratio of fibers in comparison to untreated fibers. It will be appreciated that the cellulose filaments referred to herein may relate for example, to Filocell from Kruger Inc.

[0085] The term fabric when used herein relates to any web like material that can be rolled or can be cut to specific sizes.

[0086] The term dewatering when used herein relates to processes, steps and methods for removing at least a portion of water contained in a material, for example a web of fibers, thereby obtaining a product having a lower water content. It will be understood that while drying may be a subset of dewatering, dewatering may use methods and/or equipment not used for drying materials as conventionally understood.

[0087] The term about when used in relation to a numerical amount or ranges of amounts means that deviations of plus or minus 10% of the given value are comprised in the stated amounts or ranges of amounts.

[0088] It will be appreciated that the various properties measured by the creators of the present technology result from various standard test methods.

[0089] The experimental results presented herein with respect to tensile strength and elongation were performed according to ISO standard No. 9073-3:1989 TextilesTest methods for nonwovensPart 3: Determination of tensile strength and elongation.

[0090] The experimental results presented herein with respect to disintegration were obtained according to GD4:FG502-Slosh Box Disintegration test.

[0091] The experimental results presented herein with respect to the opacity level were performed according to the standard ISO 2471 Paper and board-determination of the opacity (paper backing).

[0092] The experimental results presented herein with respect to linting were conveniently measured by standardized abrasion test.

[0093] Neither the Title nor the Abstract is to be taken as limiting in any way as the scope of the disclosed invention(s). The title of the present application and headings of sections provided in the present application are for convenience only and are not to be taken as limiting the disclosure in any way.

[0094] Various embodiments are described in the present application and are presented for illustrative purposes only. The described embodiments are not, and are not intended to be, limiting in any sense. The presently disclosed technologies are widely applicable to numerous embodiments, as is readily apparent from the disclosure. One of ordinary skill in the art will recognize that the disclosed technologies may be practiced with various modifications and alterations, such as structural and logical modifications. Although particular features of the disclosed technologies may be described with reference to one or more particular embodiments and/or drawings, it should be understood that such features are not limited to usage in the one or more particular embodiments or drawings with reference to which they are described, unless expressly specified otherwise.

[0095] Referring to FIG. 1, there is depicted an electron microscope image of the fiber structure of a nonwoven fabric. The image was recorded using backscattered electrons with an initial electrical potential of 10.0 kV, and the image has an enhancement of 500. The nonwoven fabric depicted in FIG. 1 is composed of short fibers 10 obtained from Northern Bleached Softwood Kraft (NBSK) pulp and 1.4 dtex 10 mm Lyocell long fibers 20, in an 80%/20% proportion.

[0096] Short fibers 10 are typically obtained by mechanically or chemically separating cellulose fibers of a plant-based material such as wood. Wood pulp is composed of short fibers 10 that have irregular shapes and that have a length of about 2 mm to 5 mm, and a width and thickness in the 10 microns to 100 microns range. In some embodiments, the short fibers 10 have a rectangular-like cross-section shape. However, the size and shape of the short fibers 10 greatly vary according to the embodiment.

[0097] While most paper is fabricated using mainly wood pulp, nonwoven fabrics often rely on incorporating long fibers 20 having a length greater than or equal to 5 mm to improve the structural aspects of the resulting fabric. Plastic free long fibers 20 are obtained by processing cellulose fiber using mechanical and/or chemical processes. For instance, Viscose, which is a long fiber obtained by dissolving pulp and then reconstituting it by dry jet-wet spinning, is used massively worldwide as long fibers 20 in various products. The person skilled in the art understands that long fibers 20 may be commonly referred to as polymers. The long fibers 20 used in the present technology typically have a cylindrical shape having a length between 5 and 14 mm and a radius of tens of microns. As opposed to the short fibers 10 contained in wood pulp, the size and shape of long fibers 20 may be generally uniform.

[0098] In the embodiment depicted in FIG. 1, short fibers 10 are intertwined with long fibers 20 on a microscopic scale, which suggests a mechanical cohesion between the material composing the nonwoven fabric.

[0099] Referring to FIG. 2, there is depicted an electron microscope image of the fiber structure of a nonwoven fabric comprising cellulose filaments (CF). The image was recorded using backscattered electrons with an initial electrical potential of 10.0 kV, and the image has an enhancement of 500. The nonwoven fabric depicted in FIG. 2 is composed of short fiber 10 obtained from NBSK pulp, long fiber 20 and CF 30, in an 80%/15%/5% proportion.

[0100] CF 30 is an engineered groundbreaking material first described in United States Patent Application Publication No. US 2011/0277947 A1 (Hua et al.), published on Nov. 17, 2011, entitled Cellulose Nanofilaments and Method to Produce Same. CF 30 is obtained by mechanically breaking down wood pulp into thin and long polymer chains in a mechanical, chemical free, zero waste process which produces long and thin high aspect ratio filaments in the form of moist or dry fluff ready to be used. As opposed to microfibrillated cellulose (MFC), crystalline nanocellulose (CNC), super microfibrillated cellulose, nanocellulose, cellulose microfibrils, cellulose nanofibrils, nanofibers, nanocellulose, microcrystalline cellulose (MCC), microdenominated cellulose (MDC), and the like, CF 30 provides unique intrinsic properties and characteristics. More precisely, CF 30 has an average diameter of 30 nm to 500 nm, and an average length of about 200 microns to 2 mm, which results with a much higher aspect ratio than other types of microscopic cellulose-derived products.

[0101] The nonwoven fabric depicted in FIG. 2 is composed of 5% CF 30 and has a denser structure than the one depicted in FIG. 1. As best seen in the bottom-right corner, CF 30 forms links in the short fibers 10 and Lyocell long fibers 20 matrix. Thus, without being bound by any particular theory, the CF 30 may solidify and strengthen the short fibers 10 and long fibers 20 matrix by acting as a binding agent therein, by providing more entanglement points. Further below are presented quantitative values of the mechanical properties of CF-comprising and non-CF-comprising nonwoven fabrics, in accordance with a given embodiment. It will be appreciated that the bonding induced by CF 30 may be related to covalent bonding. In one embodiment, the CF 30 is characterized by a high relative bonding area.

[0102] In one embodiment, the nonwoven fabric has a proportion of CF 30 up to about 10%.

[0103] In one embodiment, the nonwoven fabric has a proportion of long fibers 20 up to 20%, such as in low-strength products.

[0104] In one embodiment, the long fibers 20 are selected from the group consisting of man-made fibers, regenerated cellulose and a mixture thereof.

[0105] In one embodiment, the long fibers 20 are selected from the group consisting of lyocell fibers, viscose fibers, cotton, hemp, jute, flax and a mixture thereof.

[0106] In one embodiment, the short fibers 10 are derived from a raw material selected from the group consisting of wood pulp, hemp, bamboo, bagasse, flax, natural plant fibers, cotton, and a mixture thereof.

[0107] In one embodiment, the nonwoven fabric is contained in a medium having an alcohol content of about 60% in the liquid phase. The person skilled in the art understands that isopropanol (IPA) may be used as an alcohol suited for the present technology. In some embodiments, the medium may comprise a lotion, for example a water-based lotion. Other mediums will be apparent to a skilled person.

[0108] It will be appreciated that the basis weight of the fabric may greatly vary according to the product and may vary from about 10 GSM (gram by square meter) to 500 GSM, preferably from 40 GSM to 85 GSM.

[0109] It will be understood that the nonwoven fabric of the present disclosure provides a synergistic effect whereby CF may replace at least a portion of man-made fibres, for example long fibres 20, in a nonwoven while providing similar or improved strength. Accordingly, the nonwoven fabric of the present disclosure may be flushable and eco-friendly without impairing product quality.

[0110] Referring to FIG. 3, there is depicted a schematic view of a system 100 for fabricating a nonwoven fabric.

[0111] The system 100 generally comprises a wet-laying unit 110 that forms a web from a liquid suspension, a patterning unit 120 that binds the web into a fabric, a dewatering unit 130 that removes the majority of the water in the fabric, a drying unit 140 that removes any water left in the fabric, a calendering unit 150 that smooths the fabric, a sensing unit 160 that monitors the output or resulting fabric and a winding unit 170 that produces rolls of fabrics. It will be appreciated that the components of the system 100 presented herein may vary between embodiments, and that the present technology is not limited to the presented components.

[0112] In some embodiments, the feedstock entering the system 100 may be a liquid suspension comprising wood pulp, which comprises short fibers 10, long fibers 20 and CF 30. The liquid suspension typically has a consistency between 0.01 and 0.05% The liquid used to form the suspension typically is water. Other liquids and/or components may be present and will be apparent to the skilled person.

[0113] In operation, the fibers in suspension are deposited on a porous surface to separate the fibers from the fluid to form a web. The mesh-like porous surface is mounted on a conveyor belt having a defined speed that exits the wet-laying unit 110 with the deposited web. The person skilled in the art understands that the speed of the conveyor belt and the flow rate of the liquid suspension affects the thickness and the density of the deposited web. In an embodiment, the output of the wet-laying unit is a web.

[0114] The patterning unit 120 is configured to receive the deposited web and form a fabric therewith. It will be appreciated that the patterning unit 120 may bind the web by various means and processes. For instance, the patterning unit 120 may use a bonding method selected from the group consisting of thermal bonding, hydroentangling, ultrasonic pattern bonding, embossing, needle punching, chemical bonding, and the like. While the present technology is not limited to a particular bonding method, a preferred embodiment is presented and detailed below.

[0115] In one embodiment, the patterning unit 120 comprises a hydroentanglement unit. The person skilled in the art is aware that a hydroentanglement unit comprises a series of water jets projecting pressurized water onto the web, thereby causing the fiber content to intertwine and to bind together. An advantage of the hydroentanglement method is that it creates a highly intertwined pattern without using chemical additives or high temperatures.

[0116] In operation, the fibrous web goes through the patterning unit 120 in a defined direction, thereby creating a patterned fabric that is bound. The person skilled in the art understands that different patterns impact MD and CD properties in different ways.

[0117] The dewatering unit 130 and/or the drying unit 140 is configured to receive the bound fabric outputted by the patterning unit 120, the bound fabric generally containing water. In the dewatering unit 130, the fabric may be dewatered by stretching the fabric in the MD and/or CD direction, by blowing heated or non-heated air or other gas onto the fabric and by any other methods promoting the migration of water outside of the fabric. In one embodiment, the dewatering unit 130 comprises a through air drying (TAD) unit, which is a type of unit well known by the person skilled in the art. In one embodiment, the dewatering unit is a suction box dewatering unit, or a vacuum box dewatering unit. Other acceptable dewatering means and/or units will be apparent to a skilled person. In one embodiment, the output of the dewatering unit 130 is a dewatered fabric. It will be appreciated that the dewatering unit 130 may be present before and/or after the patterning unit 120, in accordance with the embodiment.

[0118] The drying unit 140 is configured to receive the dewatered fabric outputted from the dewatering unit 130. During the dewatering step, most of the water used in subsequent steps that is absorbed by the fabric is removed therefrom. However, the fabric typically remains moist when exiting the dewatering unit 130 and generally needs to be further dried before entering the calendering unit 150. The drying unit 140 comprises lamps that project radiation onto the surface of the dewatered fabric thereby heating its content. The heat created by the incoming radiation evaporates the remaining water in the fabric. In one embodiment, the output of the drying unit 140 is an essentially dried fabric.

[0119] In one embodiment, the drying unit 140 comprises infrared (IR) lamps.

[0120] While some patterning and/or web creating methods do not involve water in the process, the person skilled in the art understands that the dewatering unit 130, the drying unit 140 and/or the calendering unit 150 may be optional in some embodiments of the system 100. However, the person skilled in the art also understands that it is preferable that the system 100 includes at least one of the dewatering unit 130 and the drying unit 140 when the patterning unit 120 comprises an hydroentanglement unit and when using a wet-laying unit 110.

[0121] It will be appreciated that the patterning unit 120, the dewatering unit 130 and the drying unit 140 may be combined and/or interchanged with one another, according to the embodiment.

[0122] The calendering unit 150 is configured to receive the essentially dried fabric from the drying unit 140. Generally, the calendering unit 150 comprises a series of rolls that compress the fabric to create a smooth finish and/or patterns and designs on the surface. It will be appreciated that the calendering unit 150 may treat the fabric by various means and processes. For instance, the calendering unit 150 may use a calendering method selected from the group consisting of beetling, watering, embossing, Schreiner embossing, and the like. In one embodiment, the output of the calendering unit 150 is a calendered fabric.

[0123] In one embodiment, the series of rolls comprised in the calendering unit 150 are heated.

[0124] In some embodiments, the system 100 further comprises an embossing unit. An embossing unit typically comprises a roll having a patterned surface that applies pressure on a fibrous web, thus reproducing the pattern in the web. In some embodiments, the system 100 comprises a hydroembossing unit, which applies pressure using water jets on the fabric that is in contact with a patterned drum. It will be appreciated that hydroembossing is typically done without heating the fabric.

[0125] The sensing unit 160 is configured to receive the calendered and/or embossed fabric. The sensing unit 160 generally comprises humidity sensors, weight scales, spectrometers, opacity sensors and other means of monitoring the fabric. It will be appreciated that the measurement means comprised in the sensing unit 160 vary according to the embodiment.

[0126] The output of the sensing unit 160 is typically the same as its input, i.e., the calendered and/or embossed fabric. Therefore, the person skilled in the art understands that the sensing unit 160 may be optional in some embodiments, as it mainly serves to monitor and control the produced fabric.

[0127] In one or more embodiments, the sensing unit 160 control the process parameters of the subsequent units according to the measurements made on the calendered and/or embossed fabric. For instance, the sensing unit 160 may control the flow rate of the liquid suspension in the wet-laying unit 110, may control the pressure of the water and the number of water jets used in the patterning unit 120, may control the temperature and the flow rate of the air used in the dewatering unit 130, may control the electrical current provided to the lamp in the drying unit 140, may control the pressure or the heat of the rolls in the calendering unit 150 and the like.

[0128] In one embodiment, the sensing unit 160 controls the speed of the conveyor belt used in the system 100.

[0129] The winding unit 170 is configured to receive the resulting fabric and for forming a roll of fabric. In operation, the winding unit 170 is connected to an extremity of the continuous feed of fabric outputted by the calendering unit 150 or the sensing unit 160, and creates a force on the fabric so that the latter remains straight in the various units of the system 100. Once a sufficient amount of fabric is winded by the winding unit, the roll of fabric installed in the system 100 is removed therefrom and a new roll is installed.

[0130] Referring to FIG. 4, there is depicted a flowchart that illustrates a method for making a nonwoven fabric.

[0131] According to processing step 200, a suspension is prepared. Generally, the suspension prepared comprises, but is not limited to, CF, long fibers and short fibers. During the preparation, each component is mixed using a mixer until a sufficiently homogeneous distribution is obtained. Once the mixture is obtained, it is combined with water to obtain the desired consistency to thereby obtain the suspension.

[0132] In one embodiment, the components are directly mixed with water.

[0133] In one embodiment, in the context of air-laying for instance, the mixture is not combined with water.

[0134] According to processing step 210, a web is formed. The formation of the web varies according to the embodiment. In one embodiment, the web is formed by wet-laying, or air-laying carding/crosslapping the suspension. In operation, the suspension or the mixture is deposited on the surface of a conveyor belt thereby forming the web.

[0135] In one embodiment, the fibers contained in the suspension or the mixture are aligned mechanically during processing step 210. The alignment may be MD, CD or any other orientation, in accordance with the embodiment.

[0136] According to processing step 220, a fabric is obtained by binding the web. In operation, the structure of the web formed at processing step 210 is mechanically and/or chemically bound so that it forms a uniform yet nonwoven fabric. It will be appreciated that the web may be bound using a dry process or a wet process, according to the embodiment.

[0137] In one embodiment, the processing step 220 is processed by hydroentangling the web.

[0138] According to processing step 230, the fabric is dried. After being bound, the fabric generally contains a certain amount of water.

[0139] In one embodiment, the processing step 230 comprises a TAD unit.

[0140] In one embodiment, the fabric is dewatered before being dried.

[0141] According to processing step 240, the fabric is calendered. In most cases, the calendering process of processing step 240 is the last step that modify the structure of the fabric. In accordance with the embodiments presented above, the fabric is pressed between rolls so that the surface is smoothed. In one or more embodiments, the processing step 240 is performed by beetling, watering or embossing the fabric.

[0142] In one embodiment, the fabric properties are measured after being calendered.

[0143] In one embodiment, the fabric is wound after being calendered or measured.

[0144] Referring now to FIG. 5, a process for producing a nonwoven fabric is presented. It has been unexpectedly discovered that using never-dry pulp, i.e. pulp that has not undergone conventional drying following its production and prior to its use in manufacturing, in the manufacture of nonwovens provides several advantageous effects.

[0145] The process comprises providing a never-dried pulp in a suspension (501). The suspension may be a suspension of the pulp in water, in a solvent, or in mixtures thereof, The suspension may have a liquid to solids ratio and other characteristics appropriate for the predetermined parameters of the nonwoven to be manufactured. The suspension may comprise CF. The suspension may comprise long fibers, for example man-made fibers, for example Tencel or Lyocell or Rayon or other suitable fibers, or for example long fibers as described above.

[0146] The suspension may then be processed by forming a web (502), for example a web of pulp fibers. It will be understood that web forming may be accomplished by acceptable in the papermaking and nonwoven arts. For example, the suspension may be dynamically mixed and the web may be formed in or by a wet-laying unit, for example by depositing the suspension onto a porous surface to separate liquids from solids. In a non-limiting embodiment, the web may be formed by passing one or more porous sheets through the suspension, thereby depositing solids on one surface of the sheet and forming a web. Other web-forming methods are possible.

[0147] The formed web may then be dewatered (503). It will be understood that dewatering comprises the removal of at least some of the liquid or liquids present in the web formed at step 502. For example, dewatering may comprise removing at least 10% of the liquids contained in the formed web. Dewatering may comprise removing up to 90%, or 95%, or 99% of the liquids contained in the formed web. It will be understood that, for the purpose of this disclosure, drying is a form of dewatering wherein the resulting product is substantially dry.

[0148] The dewatered web may comprise up to 95% water. In embodiments, the dewatered web may comprise between 30% and 85% water, or between 40 and 75% water, or other levels of dewatering and/or drying. Dewatering levels appropriate for the predetermined characteristics and a predetermined use of the final nonwoven product will be apparent to the skilled person.

[0149] The formed web may then be entangled (504). It will be understood that several entangling methods may be suitable for the process 500. For example, the web may be hydroentangled. The web may be mechanically entangled, for example by felting, looming, needling and other acceptable methods.

[0150] The entangled web may then be further dewatered and/or dried (505). For example, the entangled web may be dried to form a substantially dry nonwoven, for example a fabric suitable for producing a wipe. The entangled web may be partially dewatered whereby the entangled web maintains its structure under light or moderate strain, however maintains a high moisture and/or liquid content. For example, the entangled web may be partially dewatered to form a wet wipe.

[0151] The process 500 provides one or more advantages over conventional nonwoven manufacturing processes. For example, the process 500 provides improved opacity and improved bulk for a nonwoven product.

[0152] Furthermore, it has been unexpectedly discovered that nonwovens produced using never-dried pulp show improved wet and dry tensile strength compared to nonwovens produced using market or dried pulp.

[0153] It has been further unexpectedly discovered that, despite the improved wet and dry tensile strength, a nonwoven produced according to the process 500 meets IWSFG and GD4 flushability standards.

[0154] A further advantage provided by a nonwoven produced according to the process 500 comprises improved eco-friendliness. For example, the nonwoven provides improved tensile strengths whilst being plastic-free. Accordingly, such a flushed nonwoven may disperse releasing less plastics into the environment compared to a conventional nonwoven of comparable strength.

[0155] The process 500 may comprise providing additional components. The suspension may comprise other components, for example colour additives, scent additives, cleaning additives, detergents, hydrating additives and other additives suitable for an intended use of the nonwoven.

[0156] It will be understood that the nonwoven formed according to the process 500 may be suitable for making a variety of products, such as nonwoven fabrics, for example wet wipes, dry wipes and/or flushable wipes.

Experimental Data

[0157] Hereinunder are presented quantified properties of nonwoven fabrics in accordance with embodiments presented herein.

TABLE-US-00001 TABLE 1 Sample Compositions LONG SHORT CF FIBERS FIBERS Basis CON- CON- CON- weight Caliper TENT TENT TENT SAMPLE MATERIALS (GSM) (mm) (%) (%) (%) 1 Lyocell- 40.9 0.31 0 40 60 Northern Bleached Softwood Kraft (NBSK) 2 CF-Viscose- 45.3 0.31 6 30 74 NBSK 3 CF-Lyocell- 36.8 0.23 10 20 70 NBSK

TABLE-US-00002 TABLE 2 Structural properties of nonwoven samples according to Table 1. SAMPLE SAMPLE SAMPLE PROPERTY 1 2 3 Dry MD tensile 10.5 36.0 54 strength (N/50 mm) Dry CD tensile 5.8 18.0 31 strength (N/50 mm) Wet MD tensile 4.9 5.1 6.5 strength (N/50 mm) Wet CD tensile 3.1 5.2 6.4 strength (N/50 mm) Dry MD elongation (%) 9 7 4 Dry CD elongation (%) 16 27 13 Wet MD elongation (%) 21 32 29 Wet CD elongation (%) 29 33 26 Water absorptive capacity (g/g) 6.68 6.84 8.10 IPA absorptive capacity (g/g) 6.12 5.11 4.24 wicking rate in 10 seconds (mm) 41.5 32.0 27.5 wicking in 30 seconds (mm) 63.5 53.5 43.0 Disintegration rate 92.4 97.7 100.0 in 30 minutes (%) Dry linting (%) 0.63 0.01 Dry Degradation (%) 5.96 2.14 Opacity ISO (%) 52.06 57.01

[0158] As it appears from tables 1 and 2, CF addition significantly improved several characteristics of a nonwoven. In particular, in some embodiments CF addition improved the tensile strength, while maintaining flushability. Furthermore, CF addition improved the tensile strength and other characteristics of a nonwoven despite a reduction in overall long fiber content. For example, a 5% increase in CF content between samples 2 and 3 resulted in a marked tensile strength increase despite a 10% reduction in long fiber content. It will be apparent to a skilled person that a reduced long fibre content is advantageous at least for the reasons of reducing man-made fiber content in a flushable nonwoven and improving the nonwoven's degradation properties once used and/or disposed of.

[0159] It will be understood that uniformity of the tensile strengths of a nonwoven product may be a desirable quality. For example, a nonwoven product exhibiting lower strength uniformity may provide pockets or areas of higher strength interspersed with lower-strength areas or pockets, leading to lower product strength overall, for example during use, for example during dispensing and use as a wipe.

[0160] Strength uniformity is related to the distribution of tensile strength, which follows a Weibull distribution according to the following equation wherein the term m denotes the Weibull modulus, also known as m-factor, an indicator of distribution uniformity:

[00001]$F\left(T;A\right)1-\exp \left\{-{\mathrm{pq}\left(\frac{T}{T_s}\right)}^m\right\}$

[0161] Higher values of the Weibull modulus are indicative of greater uniformity. Accordingly, products exhibiting a higher Weibull modulus when tested for characteristic strength may have greater strength uniformity and thus be less susceptible to web breakage.

[0162] Referring now to Table 3 and to FIGS. 6 to 9, results for strength distributions for several samples of nonwoven fabric are presented.

TABLE-US-00003 TABLE 3 Strength and strain test nonwoven sample compositions Sample ID GSM Filocell NBSK Tencel Remarks Sample A 40 0 60 40 Tencel 10/1.4 dtex Sample B 40 10 70 20 Tencel 10/1.4 dtex Sample C 45 0 60 40 HE 1 strip, lab Sample D 60 0 80 20 HE 1 strip, lab Sample E 45 10 65 25 Tencel 10/1.4 dtex Sample F 45 0 70 30 Tencel 8 mm/1.15

[0163] Referring to FIG. 6, samples B and E exhibit higher characteristic strengths overall. The characteristic strength is the location of the center peak of the Weibull distribution. The higher the characteristic strength, the stronger the fabric is overall. Samples B and E comprise CF, namely Filocell, while the other samples do not comprise CF. Accordingly, CF appears to markedly improve the characteristic strength of a nonwoven fabric.

[0164] Referring to FIG. 7, the samples tested exhibit characteristic strains ranging between about 2% and about 7%. The characteristic strain is the location of the center peak of the Weibull distribution. The higher the characteristic strain, the less stretch the nonwoven has overall. Accordingly, CF does not appear to significantly affect the characteristic strain of a nonwoven, thus maintaining stretch properties compared to conventional, non-CF comprising nonwovens.

[0165] Referring now to FIG. 8, the samples exhibit a high Weibull fit. Accordingly, the samples' characteristics substantially align with a Weibull distribution and thus an m-factor analysis may provide relevant results.

[0166] Referring now to FIG. 9, samples B and E exhibit a markedly higher Weibull modulus than the remaining samples. In particular, it should be noted that the Weibull modulus scale is logarithmic, and accordingly samples B and E perform impressively compared to the remaining samples. The addition of CF, for example of Filocell, to a nonwoven fabric markedly increases the strength uniformity of a nonwoven. Improved strength uniformity is desirable, in particular for consumers, for example consumers of wet or dry wipes. A product exhibiting higher strength uniformity may be less susceptible to breaking, tearing or disintegrating suddenly and unexpectedly when exposed to stress or to strain during ordinary use.

[0167] The results of strength and strain tests presented in FIGS. 6-9 are summarized in Table 4.

TABLE-US-00004 TABLE 4 Strength and strain test result summary Chara- Chara- Weibull Number cter- cter- mod- of MD Basis Mean istic istic ulus Wei- strips weight tensile strength strain (m- bull Sample measured (g/m2) (N/m) (N/m) (%) factor) fit A 99 11.0 163 169 6.7 13.04 0.97 B 100 10.7 945 972 2.3 18.70 0.99 C 100 12.3 226 237 2.4 10.06 0.97 D 91 18.0 447 470 4.7 9.77 0.96 E 100 13.2 1287 1328 5.0 17.16 0.98 F 100 11.3 670 696 20.9 13.24 0.99

[0168] Referring now to Table 5 and to FIGS. 10-11, the results of strength tests on nonwoven samples comprising market pulp, never-dry pulp and CF are presented. The never-dry pulp, market pulp and CF were sourced from NBSK. Accordingly, Table 5 displays, in particular, the impact of using never-dry pulp while the source species remain substantially the same. The compositions of the nonwoven samples are summarized in Table 5. For greater clarity, the sample denoted NR6364 in two columns of Table 5 refers to the same sample and to the same tests performed on said sample. The sample is described as market pulp for the purpose of distinguishing the sample from a nonwoven comprising never-dry pulp, and as CF(0) for the purpose of distinguishing the sample from a nonwoven comprising CF.

TABLE-US-00005 TABLE 5 Comparison of characteristics of never-dry pulp, market pulp and CF-containing nonwoven samples. Never Market Pulp Pulp Dry Pulp pulp (80)/MMF (85)/MMF (80)/MMF (80)/MMF (20)/CF (10)/CF (20) (20) (0) (5) Properties Units NR6061 NR6364 NR6364 NR 80 Total Hydroentanglement kW/m 2.9 2.9 2.9 1.7 Energy Basis weight g/m2 69.9 71.9 71.9 67.8 Caliper mm 0.528 0.514 0.514 0.468 Dry MD Tensile N/50 mm 66.8 41.9 41.9 101 Dry CD Tensile N/50 mm 27.4 19.5 19.5 24.25 Wet MD Tensile N/50 mm 10.9 8.2 8.2 9.8 Wet CD Tensile N/50 mm 6.6 5.2 5.2 3.6 Absorbency g/m2 544 533 533 437 Opacity % 79.1 75.1 75.1 76.7 IWSFG Slosh box % 96.7 100 100 95.2 dispersion, %

[0169] Referring to FIGS. 10A and 10B, samples comprising never-dry pulp exhibit greater tensile strength both in MD and CD directions in both wet and dry states than samples comprising market pulp. Indeed, samples comprising never-dry pulp appear to exhibit approximately 25-50% greater strength than market pulp-comprising samples.

[0170] Referring to FIGS. 11A and 11B, samples comprising CF show a marked improvement in dry tensile strengths in MD and CD directions compared to samples comprising market pulp. CF appears to affect wet tensile strength of a nonwoven differently. As shown in FIG. 11B, nonwoven samples comprising CF exhibited greater wet tensile strength in the MD patterning direction, however exhibited a lower wet strength in the CD direction.

[0171] Referring now to Table 6 and to FIGS. 12 and 13, the results of a dry lint test on nonwoven fabric samples are presented. Table 6 presents the compositions of nonwoven samples for the purpose of the dry lint test.

[0172] The dry lint tests were performed by rubbing samples for 60 seconds with 1000 g weight in the CD direction over the matte side of a lot of 7 black felts.

TABLE-US-00006 TABLE 6 Dry lint test nonwoven sample compositions Sample Pulp % Tencel % CF % Remarks S1 60 40 0 S2 70 20 10 5H 80 20 0 MTT4 5G 80 20 0 MTT6 10A 80 15 5 MTT4 1D 60 40 0

[0173] Referring to FIG. 12, a dry lint test may comprise rubbing a nonwoven sample on a surface which may cause friction or resistance, for example on black felt. Appropriate lint testing methods will be apparent to a skilled person. For the purpose of this disclosure but without limiting its scope, lint refers to bundles built up of many fibers, while dust refers to individual fibers removed by rubbing onto the black felt FIG. 12A shows significant lint production by a sample, corresponding to a higher lint %. FIG. 12B shows the dry lint test result of a sample exhibiting substantially no linting.

[0174] It will be understood that both lint and dust production may not be desirable in a nonwoven sample. Accordingly, for brevity only, the term lint will denote both lint and dust in the results that follow.

[0175] Referring to FIG. 13, nonwoven samples comprising both a 60/40 and an 80/20 pulp to man-made fibre proportion exhibited lint and dust production. In particular, samples comprising a lower proportion of man-made fibres, but no CF, exhibited on average substantial lint production. Conversely, samples comprising CF exhibited substantially no average lint production. Accordingly, CF may be advantageously used in nonwovens to reduce man-made fibre content, improve degradability and maintain flushability while reducing or eliminating undesirable linting and/or dust production.

[0176] Referring now to Table 7 and to FIG. 14, the results of wet lint tests on nonwoven samples are presented. Table 7 summarizes the compositions of the nonwoven samples used for the wet lint test.

[0177] The wet lint tests were conducted by soaking the samples between 1 and 10 seconds prior to testing, followed by testing according to the same conditions as the dry lint test.

TABLE-US-00007 TABLE 7 Wet lint test nonwoven sample compositions Sample Pulp % Danufil % Tencel % CF % Remarks 5G 80 20 MTT6 5H 80 20 MTT4 6B 80 20 MTT4 6C 80 20 MTT6 7A 85 15 MTT4 8A 82 15 0 3 MTT4 8B 82 15 0 3 MTT6 9A 80 15 5 MTT4 10B 80 15 5 MTT6

[0178] Referring to FIG. 14, average wet linting performance did not appear to improve through the addition of CF. For example, samples 8A, 8B and 10B, comprising CF exhibited a similar performance to sample 7A, which did not comprise CF, while sample 9A exhibited a higher linting percentage. Without being bound to any particular theory, it is possible that CF may provide lower overall hydroentanglement in a wet state, leading to higher linting.

[0179] Referring to FIGS. 15 and 16, results of linting tests on nonwoven samples are presented. FIGS. 15A and 15B show the results of a dry linting test on a 75 gsm nonwoven sample comprising no CF and 5% CF respectively. Average measured lint percentages were 1.35 (no CF) and 0.28 (5% CF). FIGS. 15C and 15D show the result of wet linting tests on the same samples, where the samples had been soaked overnight. Average measured lint percentages were 1.59 (no CF) and 0.18 (5% CF).

[0180] For greater clarity, FIGS. 16A and 16B show a magnified portion of FIGS. 15A and 15B respectively.

[0181] It will be understood that reducing dry linting is also particularly advantageous in a manufacturing context. For example, during manufacture, nonwoven fabric may be subject to friction against one or more surfaces, such as machine surfaces, rolling drums, calendering units, cutters, transporters and other sheets of nonwoven fabric. Accordingly, fabrics exhibiting higher lint and dust percentages may cause significant particulate dispersion in the manufacturing and/or processing area. Particulate accumulation may be especially dangerous as it may cause health hazards and fire/explosion hazards, for example a dust explosion. Accordingly, a process and/or a product producing less lint and/or dust may be safer. It will also be understood that CF addition may thus be desirable from a manufacturing perspective to reduce dry linting regardless of the impact of CF on wet linting, depending on the intended use and characteristics of the nonwoven product.

[0182] Referring now to Table 8 and FIGS. 17 to 18, dry degradation test results simulating use of a nonwoven fabric are presented.

[0183] Table 8 summarizes the dry and wet degradation test results for two samples, marked X and Y, where sample X contained no CF and sample Y contained 5% CF. Dry degradation tests were performed by scrubbing the samples against a ceramic tile with 750 g weight for 100, 200, 300 and 500 scrubs. Wet degradation tests comprised a soaking time of 20 seconds. Degradation was rated on a scale of 1 to 10, where 10 represents total degradation and 0 represents no degradation. Representative degraded samples and corresponding degradation ratings are shown in FIG. 17.

TABLE-US-00008 TABLE 8 Average dry and wet degradation test results Dry Wet Scrubs X Y X Y 100 4.58 4.07 200 5.17 4.33 300 7.33 4.15 350 7.7 7.45 500 8.00 3.98 7.93 7.67

[0184] As shown in Table 8, the samples comprising 5% CF exhibited remarkable resistance to degradation even following 500 scrubs, while samples not comprising CF showed a level of degradation that made them unsuitable for use.

[0185] FIG. 18 presents dry degradation results for a selection of the samples presented in Tables 6 and 7. CF addition in samples S2 and 10A provided significant improvement in resistance to degradation during use. This is consistent with findings that CF contributes to improved dry tensile strength without significantly affecting the stretch of the nonwoven fabric.

[0186] It will be appreciated that one or more embodiments of the nonwoven fabric and method disclosed herein are of great advantage.

[0187] More precisely, one advantage of one or more embodiments of the methods and the product disclosed herein is that the present invention provides a product with performant structural properties while being easily disposable.

[0188] Another advantage of the technology disclosed herein is that the present invention provides a product that may be essentially conceived using wood pulp and mechanically obtained product thereof.

[0189] Another advantage of the technology disclosed herein is that the present invention reduces the amount of lint and dust in the manufacturing process, which greatly reduces risk of unwanted fires and other accidents.

[0190] The embodiments described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the appended claims.