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.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a U.S. National Phase Application under 35 U.S.C. § 371 of International Patent Application No. PCT/EP2022/052411 filed Feb. 2, 2022, which claims priority to GB Application No. 2101624.1 filed Feb. 5, 2021, the disclosure of which is herein incorporated by reference in its entirety.

TECHNICAL FIELD

The invention relates to a nonwoven fabric for use in manufacturing oral pouched products. In particular, the invention relates to a nonwoven fabric with enhanced strength and stability to be suitable for use with modern oral products.

BACKGROUND TO THE INVENTION

It is known to use such nonwoven fabrics to manufacture a pouch for containing an individual portion of a product, such as smokeless tobacco (also known as “snus”), coffee, tea, etc., from which flavour is to be extracted. Examples of pouched products formed from a nonwoven fabric can be found in US 2014/0026912 A1 and US 2012/0103353 A1.

Nonwoven fabrics have been used for many years to produce pouches for traditional smokeless tobacco product, such as snus. More recently, the market for this type of oral pouched product has expanded to encompass so-called “modern oral” products, in which the contents of the pouch can comprises a wide variety of materials, e.g. non-tobacco nicotine, flavourings, and/or other food-grade products.

Nonwoven fabrics are typically produced using one of three processes: dry-laid, wet-laid or spun melt. Each process entangles fibres or filaments into a web in a manner that does not require weaving or knitting.

A dry-aid process typically comprises forming a loose web of staple fibres, which are subsequently bonded together to create the fabric. The web may be formed by an air laying process, whereby the fibres are randomly orientated in the web. Alternatively, forming the web may include carding the fibres, which aligns their orientation. The air laid or consolidated web can be bonded using mechanical (e.g. hydroentanglement or needle punching), thermal (e.g. where the web includes thermoplastic fibres) or chemical techniques (e.g. using an adhesive binder), or a combination thereof.

A wet-aid process typically comprises forming a slurry of fibres in water or other suitable liquid, which is deposited on a screen or mesh and then dried to form the web.

A spun melt process typically forms a web from continuous filaments spun directly from liquid (i.e. melted) plastic materials.

One known type of nonwoven fabric for use in pouched products is a dry-laid carded nonwoven fabric comprises staple fibres formed from regenerated cellulose (also known as viscose or rayon) together with a thermoplastic acrylic copolymer binder which facilitates the ability of the fabric to be heat sealed and provides a soft mouth feel.

Typically, the nonwoven fabrics used to produce pouched products are water-permeable, in order to permit substances (e.g. flavour) from the contents of the pouch to flow out.

Nonwoven fabric may be used to manufacture chewable pouches. For example, US 2018/0153211 A1 discloses a nonwoven fabric for manufacturing a pouched product, in which the pouch includes an elastic mesh of thermoplastic polyamide that ensures the pouch can endure repeated deformations caused by chewing. The elastic mesh in this example has a high percentage of open area (i.e. high porosity) to enable a rapid release rate of flavour from the pouch.

US 2013/0149254 A1 discloses a perforated chewable pouch made of a food grade material selected from silicone, latex, rubber or plastic. The pouch encloses a product that can be in a gel, semi-liquid, and/or liquid form. A user chews, sucks, and/or manipulates the pouch to cause the enclosed flavour product to leach out of the perforations into the user's mouth.

US 2014/0261480 A1 discloses a pouch formed from a fabric comprising melt-blown polymer fibres having a hydrophilic surface coating. The melt-blown material can be an elastomer (e.g. polymeric polyurethane) so that the pouch can tolerate being chewed.

The appearance and mouthfeel of oral pouched products is of high importance. The staple fibres from which the nonwoven fabric is made may play an important role here. For example, DE 20 2015 102 564 U1 discloses an oral pouch made from fabric containing lyocell fibres commercially available from Lenzing AG. This document discloses that using lyocell staple fibres may make the pouch more translucent, and may also improve transition of nicotine and taste.

Similarly, EP 3 192 380 A1 discloses an oral pouched product for containing a portion of snus, in which the pouch is formed from a dry-laid nonwoven in which at least 50% of the staple fibres are lyocell, and where the dry-laid nonwoven has a basis weight of at most 25 g/m². This document discloses that these properties may yield a pouch with improved transparency and a reduced tendency to discolour during storage.

SUMMARY OF THE INVENTION

At its most general, the present invention provides a nonwoven fabric for manufacturing an oral pouched product, where the nonwoven fabric comprises a web of chemically bonded staple fibres that 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.

The staple fibres may be formed from regenerated cellulose (viscose) or otherwise conventional materials. In a preferred example, the staple fibres in the nonwoven fabric may be non-viscose. For example the staple fibres may comprise or consist of lyocell fibres with properties selected to provide strength and stability particularly suited to tobacco-free substances of the type used in modern oral products.

In some examples, it may be particularly advantageous to use biodegradable staple fibres such as lyocell in conjunction with a biodegradable binder such as polylactic acid. The resulting nonwoven fabric may then be fully compostable, and manufacturable in a sustainable manner.

Pouches made from the nonwoven fabric of the invention may be used to enclose any suitable material from which it is desirable to extract flavour, nutrients or any other chemical, e.g. for oral delivery. The pouch contents may comprise or consist of smokeless tobacco, tobacco-free nicotine, pharmaceuticals, coffee, tea, etc.

According to a first aspect of the invention, there is provided a nonwoven fabric for forming an oral pouched product, the nonwoven fabric comprising a chemically bonded web of staple fibres, wherein the staple fibres comprise lyocell, and wherein the nonwoven fabric has a basis weight greater than 25 g/m².

Herein, “chemically bonded” may mean a matrix of staple fibres that are secured together by adhesion, i.e. by a binder that acts to physically interconnect the staple fibres.

The web may be composed of a plurality of carded layers of the staple fibres. Combining a plurality of carded layers into a consolidated web may be advantageous for achieving uniformity within the fabric, and to improve its strength.

In the present application, the staple fibres may consist essentially of sustainably manufactured regenerated cellulose, such as lyocell. The nonwoven fabric contains no viscose. In the examples discussed herein, lyocell is preferably the dominant material, and may make up 100% of the staple fibres. In other examples, the staple fibres may comprise or consist of other biodegradable, compostable or sustainably manufactured materials. For example, the staple fibres may include materials such as polylactic acid (PLA), polyvinyl alcohol (PVOH), polybutylene succinate (PBS), bamboo, and natural bast fibres, such as hemp, ramie, jute, flax, kenaf and nettle.

The staple fibres may have properties selected according to the process by which the consolidated web is formed. For example, the staple fibres may have a fibre density in the range 0.9 to 4.4 dtex, preferably 0.9 to 2.2 dtex.

A lyocell-based fabric with a basis weight greater than 25 g/m² may provide enhanced resistance to natural or synthetic flavourings found in modern oral products. Typically, such flavourings have a smaller particle size than the tobacco-based substances that are conventionally used in smokeless tobacco pouches. A lower basis weight fabric may have a more open structure through which such fine particles can easily pass, thereby losing flavour more readily.

It may be desirable to strike a balance between resistance to flavour leakage in a dry state and an ability to release flavour when in an aqueous environment. The proposed lyocell-based fabric may exhibit an enhanced wet strength, which may make it capable of manipulation within the aqueous environment, e.g. by chewing, biting or sucking. This can assist in releasing flavour. The basis weight may be less than or equal to 40 g/m² in order to strike the necessary balance.

The fabric density may also contribute to the strength of the nonwoven fabric. Herein “fabric density” may correspond to the basis weight of the fabric divided by its thickness. In some examples the nonwoven fabric may have a fabric density in a range from 140 g/mm to 170 g/mmm, preferably from 150 g/mm to 160 g/mm.

The nonwoven fabric may comprise a binder. Examples are synthetic acrylic binder, polylactic acid (PLA), polybutylene succinate (PBS), polyhydroxyalkanoate (PHA), a vinyl acetate copolymer, a vinyl acrylic copolymer and a styrene-butadiene copolymer. The binder may be present in the nonwoven fabric in a range of between 30 to 50 wt % based on a dry weight of the nonwoven fabric. The binder is preferably selected from a biodegradable or biotransformable material.

The nonwoven fabric is preferably heat sealable. In this context, heat sealable may mean an ability to form a physical connection to itself upon application of heat. The heat may be applied in combination with pressure, e.g. at a certain location (seal line) on the nonwoven fabric. This property may permit an oral pouched product formed of the material to be closed using known heat sealing techniques. The heat sealable property may be provided by a binder integrated in the nonwoven fabric substrate.

The nonwoven fabric may be used to fabricate an oral pouched product, i.e. a pouch formed from the nonwoven fabric discussed above, wherein the pouch encloses a substance comprising a carrier medium for nicotine, flavourings and cannabidiol (CBD).

According to a second aspect of the invention, there is provided 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; and applying a binder to the consolidated web to bond the staple fibres together in a nonwoven fabric, wherein the staple fibres comprise lyocell, and wherein the nonwoven fabric has a basis weight greater than 25 g/m². The step of combining a plurality of carded layers of lyocell fibres into a consolidated web may be advantageous for achieving uniformity within the fabric, and to improve its strength. The combining step may be performed by drawing the layers together, e.g. overlaying the layers on a roller or the like, in advance of applying the binder.

Features of the first aspect discussed above may also apply to the second aspect.

The step of applying the binder may comprise: impregnating the consolidated web with a binder solution; and drying the impregnated consolidated web to form the nonwoven fabric. For example, the binder may be applying by dipping, spraying, or the like.

The nonwoven fabric may have an air permeability equal to or greater than 1700 l/m²/s, and more preferably equal to or greater than 2500 l/m²/s. An air permeability above this threshold may facilitate the formation of a pouched product by allowing air to escape at an appropriate rate when the contents of the pouch is enclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

The process is configured such that a resulting bonded web 124 has a basis weight greater than 25 g/m², e.g. greater than 30 g/m², up to 35 g/m 2 or even 40 g/m². 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.

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.

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

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/m2
Fabric density    140-170 g/mm
Wet strength      25-30 N/50 mm
Surface roughness RZ < 70 μm
                  RC > 50 μm
Air permeability  >1700 l/m2/s
Heat sealability  >1000 g

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.

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.

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.

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 2
Specific examples
Exam-
ple	Composition	Weight	Density
1	50% staple fibres (100% lyocell, 1.7 dtex)	30 g/m2	150 g/mm
	50% binder (vinyl acetate copolymer)
2	70% staple fibres (100% lyocell, 1.7 dtex)	35 g/m2	160 g/mm
	30% binder (vinyl acetate copolymer)
3	70% staple fibres (100% lyocell, 1.7 dtex)	35 g/m2	160 g/mm
	30% binder (PLA)

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.

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.

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.

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

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.

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%.

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/m2.

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/m2.

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/m2.

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/m2, 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.