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 configured to withstand a chewing action when in a user's mouth.

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 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-laid 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 carded 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-laid 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 manufactured by Nonwovenn under the product code SDH27, which 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. Other types of commercially available nonwoven fabrics include SDZ35, which is another type of dry-laid carded nonwoven fabric of viscose fibre having a fibre density of 1.7 dtex, together with an thermoplastic acrylic copolymer binder, and SYF32, which is a chemically (adhesively) bonded fabric of viscose fibres having a density of 1.7 dtex, polyester fibres having a density of 2.2 dtex, and acrylic binder.

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.

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 is chewable, i.e. is capable of withstanding repeated deformations in an aqueous environment without disintegrating. When the nonwoven fabric is used to form a pouch, it may thus prevent the contents of the pouch from escaping into the user's mouth.

Chewing the nonwoven fabric may act to increase its liquid permeability. When the nonwoven fabric is used to form a pouch, it may thus control the release of substances from within the pouch.

The nonwoven fabric may meanwhile exhibit air permeability to make it suitable for manufacturing a pouch.

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, pharmaceuticals, coffee, tea, etc.

According to a first aspect of the invention, there is provided a chewable nonwoven fabric for forming an oral pouched product, the chewable nonwoven fabric comprising: a nonwoven fabric substrate; and a resiliently deformable permeable material formed on the nonwoven fabric substrate.

The resiliently deformable permeable material provides a support structure for the nonwoven fabric substrate to prevent it from disintegrating when chewed.

The resiliently deformable permeable material may form a layer on the nonwoven fabric substrate. For example, the resiliently deformable permeable material and the nonwoven fabric substrate may form a two layer laminated structure. Herein the term "laminated" or "lamination" may refer to any type of attachment effected by the application of heat and/or pressure. The resiliently deformable permeable material may be provided as a pre-formed web that is attached (e.g. secured or bonded) to the nonwoven fabric substrate using any suitable technique, e.g. needle punching or the like. When formed as a pouch, the nonwoven fabric substrate may be configured to face outward in order to provide a desirable mouth feel.

The resiliently deformable permeable material may have a porosity that is less than the nonwoven fabric substrate. The resiliently deformable permeable material may thus naturally restrict the diffusion or liquid flow through the chewable nonwoven fabric. For example, the resiliently deformable permeable material may comprise a semipermeable membrane, e.g. a layer of material formed with pores having a size that restrict liquid diffusion whilst allowing gas (air) diffusion. A chewing action can change the size of the pores to permit diffusion. When used to form a pouch, the chewable nonwoven fabric thus initially inhibits the diffusion of pouch contents outwards when in an aqueous environment. This diffusion or flow restriction can be removed by chewing, thereby permitting release of the pouch contents. The pouch contents in this context may comprise a soluble flavour or medicament substance contained in the pouch.

Herein, the term "chewable" may refer to the fabric ability to resist degradation caused by repeated mechanical deformation in the presence of saliva or water. The degradation resistance desirably remains for at least a period corresponding to the usual time of consumption of a pouched product, e.g. 10 minutes or more.

The resiliently deformable permeable material may be thermoplastic polyurethane (TPU). The resiliently deformable permeable material may be a layer of thermoplastic polyurethane having a weight equal to or less than 30 gsm, preferably equal to or less than 20 gsm (e.g. 18 gsm), and more preferably equal to or less than 10 gsm. The TPU may be formed from a plurality of TPU filaments laid together in a layer. The porosity of the layer (and hence the permeability of the final laminated product) may be adjusted through selection of the filament size.

The nonwoven fabric substrate may be produced using any known process, such as the three processes mentioned above: dry-laid, wet-laid or spun melt. The nonwoven fabric substrate thus comprises a web of entangled fibres or filaments formed in a manner that does not require weaving or knitting. The nonwoven fabric substrate may be a conventional nonwoven fabric, e.g. of the type already used to manufacture oral pouched products.

In one example, the nonwoven fabric substrate may comprise a bonded web of viscose fibres and a binder, e.g. a thermoplastic acrylic binder. The viscose fibres may have a fibre density equal to or less than 5 dtex, preferably equal to or less than 2 dtex, e.g. 1.7 dtex. It should be noted that this is just one example of the type of nonwoven fibre substrate to which the invention can be applied. The effects of applying the resiliently deformable permeable material will be applicable to any type of permeable nonwoven fabric, especially those known for use in manufacturing oral pouched products.

The chewable nonwoven fabric may have an air permeability equal to or greater than 100 l/m ² /s, preferably equal to or greater than 700 l/m ² /s, and more preferably equal to or greater than 1500 l/m ² /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.

The chewable 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, as is conventional.

In another aspect, the invention provides method for manufacturing a chewable nonwoven fabric, the method comprising: forming a nonwoven fabric substrate; and applying a resiliently deformable permeable material to the nonwoven fabric substrate.

Features of the first aspect discussed above may be equally applicable to this aspect. For example, forming the nonwoven fabric substrate may be done using any conventional technique. In one embodiment, the nonwoven fabric substrate is manufactured by forming a dry-laid carded web and applying binder to the dry-laid carded web. In another embodiment, the nonwoven fabric substrate may be formed using a meltblown process.

The step of applying the resiliently deformable permeable material may comprise laminating a permeable or semipermeable polymer mesh on the nonwoven fabric substrate. The resiliently deformable permeable material may be thermoplastic polyurethane or the like.

The resiliently deformable permeable material may be applied as a deformable web. The method may comprise forming the deformable web using a meltblown process, e.g. by extruding filaments of molten polymer. The meltblown process may comprise depositing filaments of the resiliently deformable permeable material directly on the nonwoven fabric substrate. The amount of deposited resiliently deformable permeable material may be equal to or less than 30 gsm, preferably equal to or less than 20 gsm (e.g. 18 gsm), and more preferably equal to or less than 10 gsm.

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 manufacturing of a chewable nonwoven fabric that is an embodiment of the invention; and

Fig. 2 is a schematic drawing of apparatus for manufacturing a chewable laminated melt-blown nonwoven fabric that is an embodiment of the invention.

DETAILED DESCRIPTION; FURTHER OPTIONS AND PREFERENCES

In embodiments of the invention, a chewable nonwoven fabric is manufactured by depositing a resiliently deformable permeable layer on a nonwoven base layer. The resulting nonwoven material comprises a two-layer structure that presents a texture (e.g. mouth feel) that is similar to conventional nonwoven fabrics for an oral pouched product whilst also being chewable. The deformable layer may have a porous structure, in which the pores have a size selected to inhibit water diffusion when the deformable layer is in a non- deformed state. In use, the chewing action may physically deform the deformable layer to cause the pores to change in size and therefore permit diffusion, whereupon substances are released through the nonwoven fabric.

In one example, the deformable layer is formed from thermoplastic polyurethane (TPU). The TPU layer may be formed as a web using a conventional meltblown process, in which the pore size of the TPU can be controlled through the parameters of the filament generation and laying process. In a meltblown process, a microfibre nonwoven material is formed directly (i.e. in a single step) from a thermoplastic polymer. High velocity air is used to blow filaments extruded from a die towards a carrier conveyor system. Typically the fibres produced are of the range 2- 6 pm. Depositing these filaments on a conventional (macrofibre) nonwoven substrate may provide a resilient support structure that maintains the integrity of the nonwoven fabric during chewing. In some examples, the larger pores within the conventional nonwoven may be covered or filled by the thermoplastic polymer, thereby restricting its permeability.

The TPU layer in this example may thus provide a dual function. Firstly, it improves the mechanical integrity of the underlying nonwoven, especially in the stress/strain response. This ensures that the material can cope with a chewing action. Secondly, it may restrict the permeability of the underlying nonwoven, which means that a chewing action is required to enable flow therethrough. However, in other examples, the porosity of the TPU layer may be selected so that it does not affect the permeability of the underlying nonwoven. That is, the release of substances from a pouch formed by the chewable material of the invention may be substantially identical to a pouch formed from a conventional nonwoven (without a TPU layer).

In this example, a TPU layer can be attached to (e.g. laminated on) a carrier nonwoven layer. The carrier nonwoven layer may be a conventional nonwoven fabric for fabricating oral pouched products. The TPU layer may act to strengthen the conventional material to make it chewable without breaking. Using the conventional nonwoven fabric may also ensure that a pouch formed from the material has a similar mouthfeel to known pouches. It also enables the pouch to be formed using standard pouching techniques. In contrast, a pouch formed from TPU only typically has to be filled in a non-standard manner because it does not exhibit sufficient air permeability. Moreover, a pouch formed from TPU only may deform too readily to be suitable for conventional pouching techniques. For example, where a pouching technique requires the pouch material to be unwound from a roll in a controlled manner, a TPU only material may stretch in a manner that undesirably affects the resulting shape of the pouch. A method of manufacturing a nonwoven fabric that is an embodiment of the invention is now described with reference to Fig. 1. Fig. 1 is a schematic diagram showing an apparatus 100 for manufacturing a dry-laid carded carrier nonwoven to which is applied a deformable layer to form a chewable nonwoven fabric.

The apparatus 100 comprises a first process line for forming the dry-laid carded carrier nonwoven. The first process line comprises a first conveyor 102 that transports fibre bales 104 to a bale opener 106, which separates and blends the fibres from each bale. The fibre bales 104 may comprises bundles of any suitable staple fibre, such as regenerated cellulose (viscose) or the like. 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 carded web 116 on to a third conveyor 118.

The fibres in the carded web 116 may subsequently be bonded together by any conventional method. For example, a binder may be applied to the carded 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 carded web 116. The carded web 116 is then transported to nip rollers 138, which operate to remove or squeeze excess liquid from the carded web 116 before it is conveyed to a lamination module 146. The carded web 116 may pass through a dryer (not shown) before it is conveyed to the lamination module 146.

The apparatus 100 further comprises a second process line for forming a deformable web 140. In this example, the deformable web 140 is made of TPU formed using a meltblown technique. The second process line comprises an extrusion module 142 arranged to extrude filaments from molten TPU. The filaments are heated by a warm air flow before being deposited as the deformable web 140 on a fourth conveyor 144.

The deformable web 140 is transports to the lamination module 146, which is arranged to combine the deformable web 140 and carded web 116 into a laminated nonwoven fabric 148. The laminated nonwoven fabric 148 is moved into a dryer 150 for drying the web and curing or otherwise stabilising the binder.

In other examples, the carded web 116 may be mechanically bonded, e.g. using hydroentanglement (spunlace) or needle punching techniques.

In yet further example, where the carded web 116 includes thermoplastic fibres, the fibres in the web can be thermally bonded, e.g. by passing the web through heated calendar rollers.

In yet further examples, the deformable web 140 may be preformed and supplied as in a roll suitable for laying on the carded web 116.

The resulting bonded web 124 may be wound into a finished roll, or can be subjected to additional finishing steps, such a crimping, perforating or the like.

Another method of manufacturing a nonwoven fabric that is an embodiment of the invention is now described with reference to Fig. 2. Fig. 2 is a schematic diagram showing an apparatus 200 for manufacturing a laminated two-layer spun melt nonwoven. It is to be understood that manufacture of the chewable nonwoven fabric of the invention need not be limited to the techniques of Figs. 1 and 2. For example, the carrier layer to which the deformable layer is attached may be formed using other manufacturing techniques, such as wet-laid methods. Similarly, whilst the TPU layer discussed in these examples is manufactured using a meltblown process, it may be produced by any known technique for forming a web of polymer filaments.

The apparatus 200 comprises a first process line for forming a carrier nonwoven web. In this example, the carrier nonwoven web is formed using a meltblown technique. An extrusion module 202 is arranged to extrude filaments from a liquid polymer, which are heated by a warm air flow before being deposited as a web 203 on a first conveyor 204. This initial web 203 is then consolidated by applying adhesive from a pan 206 using a drum 208. Any excess adhesive is removed using a nip blade 212 or nip rollers to form a consolidated web 211. The consolidated web 211 is transported by a second conveyor 210 to a lamination module 220 and dryer 222, as explained below. Although this example discusses consolidating the initial web using adhesive (i.e. chemical bonding), it is to be understood that other types of consolidation may also be used e.g. thermal bonding or mechanical bonding.

The apparatus 200 further comprises a second process line for forming a deformable web 216. In this example, the deformable web 216 is made of TPU formed using a meltblown technique. The second process line comprises an extrusion module 214 arranged to extrude filaments from molten TPU. The filaments are heated by a warm air flow before being deposited as the deformable web 216 on a third conveyor 218.

The deformable web 216 is transported to the lamination module 220, which is arranged to combine the deformable web 216 and consolidated web 211 into a laminated nonwoven fabric 221. The laminated nonwoven fabric 221 is moved into a dryer 222 for drying or curing the adhesive.

In a particular example, the deformable web 216 formed from TPU filaments was deposited directly on a dry-laid carded nonwoven fabric manufactured by Nonwovenn under the product code SDH22, which consists of viscose fibres having a fibre density of 1.7 dtex, together with a thermoplastic acrylic binder. Other substrates may be used, such as the SDZ35 or SYF32 products discussed above.

The TPU filaments for forming the deformable web 216 in this example were blown on to the consolidated web 211 to increase its mechanical resilience. The rate of deposition was controlled to be less than 30 gsm, e.g. 18 gsm in this example. It may be desirable to control the rate of deposition such that the deformable web 216 adds a weight equal to or less than 10 gsm to the consolidate web 211.

One result of the improvement in mechanical properties provided by the deformable web, is a significant reduction in the permeability (pore size) of the consolidated web. In effect the TPU filaments span across the pores in the underlying fabrication. The reduced permeability may be a benefit in terms of controlling flavour transfer through the fabric.

The resilience of a pouched product formed by the laminated nonwoven fabric 221 may be tested using any known technique for assessing products for mastication. For example, the ERWEKA DRT device known for testing in vitro release of substances from chewing gums and the like, may be used to assess the ability of the laminated nonwoven fabric 221 to withstand a chewing environment for a relevant time period. Table 1 shows various properties of this example.

Table 1: Fabric properties The fabric weight test result was obtained using the

NWSP130.1.R0 EDANA test method. The fabric thickness test result was obtained using the NWSP120.6.R0 EDANA test method. The air permeability test result was obtained using the 140.1 EDANA test standard. The final column is a test for whether the fabric is capable of forming a pouch having the required sealing strength for use in an oral pouched product. This test result was obtained using the CORESTA Recommended Method No. 90 on a heat-sealed pouch formed from the example fabric.