NONWOVEN FABRIC FOR ORAL POUCHED PRODUCT, AND METHODS OF MANUFACTURING A NONWOVEN FABRIC

Abstract

A nonwoven fabric for use as packaging in an oral pouched product, where the nonwoven fabric comprises a web of chemically bonded staple fibres in which a relative proportion of staple fibres and a binder is selected in conjunction with a density of the fabric to strike an optimal balance in achieving a fabric that provides a soft (e.g. low friction) mouthfeel, a wet strength capable of withstanding manipulation in a user's mouth (e.g. chewing, sucking or the like), and a resistance to unwanted leaching or leaking of flavouring or other fine particle substances used in modern oral products.

Claims

1. A nonwoven fabric for forming an oral pouched product, the nonwoven fabric comprising a chemically bonded web of staple fibres and a binder, wherein the binder is present in the nonwoven fabric in an amount greater than or equal to 30 wt % based on a dry weight of the nonwoven fabric, and wherein the nonwoven fabric has a fabric density greater than 140 g/mm and a basis weight greater than 25 g/m.sup.2.

2. The nonwoven fabric of claim 1, wherein the fabric density is less than or equal to 170 g/mm.

3. The nonwoven fabric of claim 1, wherein the basis weight is less than or equal to 40 g/m.sup.2.

4. The nonwoven fabric of claim 1, wherein the binder is present in the nonwoven fabric in an amount less than or equal to 50 wt % based on a dry weight of the nonwoven fabric.

5. The nonwoven fabric of claim 1, wherein the web is composed of a plurality of carded layers of the staple fibres.

6. The nonwoven fabric of claim 1, wherein the web comprises non-viscose staple fibres.

7. The nonwoven fabric of claim 6, wherein the staple fibres are 100% lyocell.

8. The nonwoven fabric of claim 1, wherein the binder comprising any one or more of a synthetic acrylic binder, polylactic acid (PLA), polybutylene succinate (PBS), polyhydroxyalkanoate (PHA), a vinyl acetate copolymer, a vinyl acrylic copolymer and a styrene-butadiene copolymer.

9. The nonwoven fabric of claim 1, wherein the staple fibres and the binder are biodegradable or biotransformable.

10. An oral pouched product comprising a pouch formed from a nonwoven fabric, wherein the pouch encloses a substance comprising a carrier medium for nicotine, flavourings and cannabidiol (CBD), wherein the nonwoven fabric comprises a chemically bonded web of staple fibres and a binder, wherein the binder is present in the nonwoven fabric in an amount greater than or equal to 30 wt % based on a dry weight of the nonwoven fabric, and wherein the nonwoven fabric has a fabric density greater than 140 g/mm and a basis weight greater than 25 g/m.sup.2.

11. A method for manufacturing a nonwoven fabric suitable for forming an oral pouched product, the method comprising: forming a consolidated web by combining a plurality of layers of staple fibres; applying a binder to the consolidated web to bond the staple fibres together in a nonwoven fabric, wherein the nonwoven fabric has a basis weight greater than 25 g/m.sup.2, and wherein the binder is present in the nonwoven fabric in an amount greater than or equal to 30 wt % based on a dry weight of the nonwoven fabric; and controlling the thickness of the consolidated web to provide the nonwoven fabric with a fabric density greater than 140 g/mm.

12. The method of claim 11, wherein the step of forming a consolidated web comprises: discharging a dry loose fibre web of the staple fibres; and carding the loose fibre webs to form the each of the plurality of layers of staple fibres.

13. The method of claim 11, wherein the step of applying the binder comprises: impregnating the consolidated web with a binder solution; and drying the impregnated consolidated web to form the nonwoven fabric.

14. The method of claim 11, wherein the web comprises non-viscose staple fibres.

15. The method of claim 14, wherein the staple fibres are 100% lyocell.

16. The method of claim 11, wherein the binder comprises any one or more of a synthetic acrylic binder, polylactic acid (PLA), polybutylene succinate (PBS), polyhydroxyalkanoate (PHA), a vinyl acetate copolymer, a vinyl acrylic copolymer and a styrene-butadiene copolymer.

17. The method of claim 11, wherein the staple fibres and the binder the binder are biodegradable or biotransformable.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Embodiments of the invention is discussed below in more detail with reference to the accompanying drawings, in which:

[0036] FIG. 1 is a schematic drawing of apparatus for manufacture of a nonwoven fabric according to a method that is an embodiment of the invention.

DETAILED DESCRIPTION; FURTHER OPTIONS AND PREFERENCES

[0037] A method of manufacturing a nonwoven fabric according to this example is now described with reference to FIG. 1. FIG. 1 is a schematic diagram showing an apparatus 100 for manufacturing a dry-laid carded nonwoven. However, it is to be understood that the invention need not be limited to this type of manufacturing technique.

[0038] In the apparatus 100 shown in FIG. 1, a first conveyor 102 transports fibre bales 104 to a bale opener 106, which separates and blends the fibres from each bale. Any suitable cellulose-based staple fibre (e.g. viscose) may be used. However, in a preferred arrangement the fibre bales 104 may comprise non-viscose staple fibres. Lyocell is used in the examples below. In some examples the lyocell may be combined with other types of staple fibre, in particular other biodegradable fibres.

[0039] Lyocell is a form of regenerated cellulose, e.g. obtained by direct physical dissolution of wood pulp using a non-toxic solvent (e g amine oxide solution). Examples of lyocell fibre are commercially available from Lenzing AG under the trade name Tencel. Lyocell can be manufactured in a sustainable manner using a substantially closed loop process in which the solvent and water used for dissolution are fully recycled. In this example, the staple fibres are 100% lyocell.

[0040] Using lyocell is desirable not only for the sustainability reason mentioned above, but also because it provides the resulting fabric with a desirable mouthfeel and wet strength. Lyocell fibres typically have a higher degree of cellulose crystallinity compared with equivalent sized viscose fibres. This can gives lyocell fibres a fibrillar structure. The present invention uses this property to provide a nonwoven fabric with improved stability for use with substances contained in modern oral products. For example, the nonwoven fabric may exhibit a reduced absorbency of the types of micro-sized materials (e.g. certain type of flavouring, etc.) that may be used instead of tobacco-based substances in modern oral products. Accordingly, the nonwoven fabric can facilitate the passage of particulates from within the pouch along with the transfer of content materials such as nicotine, flavours and CBD.

[0041] The staple fibres in the fibre bales 104 may have any suitable cross-section. In some examples, the staple fibres consist or comprise multilobal fibres, e.g. fibres exhibiting a cross-section comprises three or more lobes. Multilobal fibres may further assist in the transfer of micro-sized materials through the nonwoven fabric.

[0042] The bale opener 106 is connected to a feed hopper 108 that discharges the blended fibres as a loose fibre web 112 on a second conveyor 110. The loose fibre web 112 is conveyed to a carding machine 114 that combs the web to apply a desired orientation or plurality of orientations to the fibres in the web. The carding machine 114 thus outputs a consolidated web 116 on to a third conveyor 118.

[0043] In some examples the consolidated web 116 may comprise a plurality of carded layers. Each carded layer may be output from a respective carding machine 114 before being combined with the other carded layers into a single consolidated web. The plurality of carded layers may be obtained by divided the loose fibre web 112 between the respective carding machines. Providing a plurality of carded layers can improve the uniformity of the consolidated web.

[0044] The carding process may be optional. For example, the consolidated web 116 may be formed directly by air laying suitable lyocell fibres. In this example, the lyocell fibres may be crimped during manufacture to facilitate web formation in an air stream. Alternatively, the consolidated web 116 may be formed directly by a wet laying process.

[0045] The fibres in the consolidated web 116 may subsequently be bonded together by any conventional method. For example, a binder may be applied to the consolidated web, e.g. by conveying it using deflector 134 into a pan 136 filled with liquid binder or binder precursor, so that the binder impregnates or saturates the consolidated web 116. The consolidated web 116 is then transported to a fourth conveyor 120 via nip rollers 138, which operate to remove or squeeze excess liquid from the consolidated web 116. The web 116 is then carried through a dryer 122, which operates to dry the web and cure or stabilise the binder. In other examples, the binder may be applied by coating or spraying.

[0046] The binder may be applied as in an aqueous solution, where the water is subsequently removed by the drying process. However, other solvents may also be used.

[0047] It may be desirable for the binder or binder precursor to emit zero or a negligible amount of volatile organic compounds (VOCs).

[0048] In some examples, the final nonwoven fabric may be fully biodegradable. In such case, the binder may be biodegradable or biotransformable. Examples of biodegradable binders include polylactic acid (PLA), polybutylene succinate (PBS), polyhydroxyalkanoate (PHA), in any combination. In other examples, the binder may include an additive capable of facilitating biotransformation of any plastic in the fabric composition. For example, a biotransforming masterbatch of the type manufactured by Polymateria Limited may be added to the consolidated web, e.g. in an amount equal to or less than 2 wt % of the dry weight of the resulting nonwoven fabric.

[0049] Other additives may be added to the consolidated web. For example, a triglyceride additive may be used to further improve the wet strength of the resulting fabric. The presence of triglyceride in the nonwoven fabric may also assist in preventing unwanted leakage of flavour particles from the contents of an oral pouched product made using the fabric.

[0050] The process is configured such that a resulting bonded web 124 has a basis weight greater than 25 g/m.sup.2, e.g. greater than 30 g/m.sup.2, up to 35 g/m 2 or even 40 g/m.sup.2. Lyocell-based nonwoven fabrics having a lower basis weight may provide structures that are too open for the type of substance used in many modern oral products. For example, many non-tobacco modern oral product may comprises materials with fine particles (e.g. having dimension less than or of the order of a micron) that may more readily pass a fabric network than more conventional macro-sized substances. The basis weight is typically achieved by selection of the relative proportion of binder to fibre matrix, and by controlling the rate at which the fibre web is laid on the conveyor. For example, the binder may provide up to 50 wt % of the resulting bonded web 124. The binder may be present in the final nonwoven fabric in a range between 30 to 50 wt %, based on the dry weight of the nonwoven fabric.

[0051] The basis weight of the resulting bonded web 124 may be selected in conjunction with a thickness of the web to provide the material with a desired fabric density. Fabric density may affect the material's air and liquid permeability. Air permeability may be important if the fabric is subsequently used in a pouching process, i.e. to form an enclosure for a substance for oral delivery. Liquid permeability may be important for the ability of the fabric to release substances into a user's mouth. Fabric density also has an impact on the strength of the fabric. The inventors have found that selecting a fabric density in the range 140 g/mm to 170 g/mm, and preferably in the range 150 g/mm to 160 g/mm, can provide an optimal balance of these factors.

[0052] Table 1 summarises the desirable composition and properties of a nonwoven fabric that is an embodiment of the invention.

TABLE-US-00001 TABLE 1 Fabric composition and properties Property Desirable characteristic Composition 50-70 wt % staple fibre 30-50 wt % binder 0-5 wt % additives Basis weight >25 g/m.sup.2 Fabric density 140-170 g/mm Wet strength 25-30 N/50 mm Surface roughness RZ < 70 m RC > 50 m Air permeability >1700 l/m.sup.2/s Heat sealability >1000 g

[0053] A given material sample may be tested for the above properties using conventional techniques. For example, the basis weight test results can be obtained using the NWSP130.1.R0 EDANA test method. The thickness of a fabric can be obtained using the NWSP120.6.R0 EDANA test method, whereupon fabric density can be measured by dividing fabric weight by fabric thickness.

[0054] Surface roughness may provide an measurable parameter that is indicative of mouthfeel. It can be measured using an industry standard surface roughness tester machine, e.g. SurfTest SJ-210. Wet strength can be measured using the 20.2-89 EDANA test method. The air permeability can be obtained using the 070.1.R3 (12) EDANA test method.

[0055] The final property relates to a test for whether the fabric is capable of forming a pouch having the required sealing strength for use in an oral pouched product. These test results can be obtained using the CORESTA Recommended Method No. 90 on a heat-sealed pouch formed from the relevant fabric.

[0056] Table 2 illustrate three example fabric compositions that are embodiments of the invention. The composition of the fabrics is selected to provide an optimised combination of weight and density to yield the desired strength, mouthfeel, permeability and heat sealing required of a material that is to form an oral pouched product. The third example is a fully biodegradable material.

TABLE-US-00002 TABLE 2 Specific examples Exam- ple Composition Weight Density 1 50% staple fibres (100% lyocell, 1.7 dtex) 30 g/m.sup.2 150 g/mm 50% binder (vinyl acetate copolymer) 2 70% staple fibres (100% lyocell, 1.7 dtex) 35 g/m.sup.2 160 g/mm 30% binder (vinyl acetate copolymer) 3 70% staple fibres (100% lyocell, 1.7 dtex) 35 g/m.sup.2 160 g/mm 30% binder (PLA)

[0057] The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

[0058] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

[0059] For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

[0060] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0061] Throughout this specification, including the claims which follow, unless the context requires otherwise, the word comprise and include, and variations such as comprises, comprising, and including will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0062] It must be noted that, as used in the specification and the appended claims, the singular forms a, an, and the include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent about, it will be understood that the particular value forms another embodiment. The term about in relation to a numerical value is optional and means for example +/10%.