WO2015150718A1

WO2015150718A1 - Filter materials and filters made therefrom

Info

Publication number: WO2015150718A1
Application number: PCT/GB2014/051014
Authority: WO
Inventors: Peter Branton; John Sampson; Gordon Grierson; Rosa GALATI
Original assignee: British American Tobacco (Investments) Limited
Priority date: 2014-03-31
Filing date: 2014-03-31
Publication date: 2015-10-08

Abstract

The present invention relates to filter material for inclusion in a smoking article, wherein the filter material comprises fibres comprising cellulose acetate and polyethylene oxide. The invention also relates to processes for preparing filter material for inclusion in a smoking article, the filter material comprising fibres which comprise cellulose acetate and polyethylene oxide, the process comprising electrospinning or centrifugal spinning of a solution comprising cellulose acetate and polyethylene oxide or melt spinning a mixture comprising cellulose acetate and polyethylene oxide. The invention further relates to filters or filter elements comprising the filter material, smoking articles comprising the same, and use of the filter material in smoke filtration.

Description

Filter materials and filters made therefrom

Field

The present invention relates to filter materials for use in smoking articles. The invention also relates to filters or filter elements comprising the filter materials, smoking articles comprising the same, and use of the filter materials in smoke filtration.

Background

A wide variety of fibrous materials have been suggested as filters for cigarette smoke. Cellulose acetate tow is the most commonly used filter material and the fibres generally have a mean diameter in the region of 20 μπι.

Summary

According to a first aspect of the invention, a filter material for inclusion in a smoking article is provided, wherein the filter material comprises fibres which comprise cellulose acetate and polyethylene oxide.

In some embodiments, the fibres comprising cellulose acetate and polyethylene oxide have a flattened cross sectional shape.

In some embodiments, the fibres comprising cellulose acetate and polyethylene oxide have a mean width of from about 1 μπι to about 15 μπι. In some embodiments, the filter material is in the form of a tow or non-woven sheet is formed from fibres and at least about 80% by weight of the fibres are fibres which comprise cellulose acetate and polyethylene oxide.

In some embodiments, the fibres comprise cellulose acetate, polyethylene oxide and an additive.

In some embodiments, the filter material further comprises a plasticizer which is one or more selected from the group consisting of: triacetin; polyethylene glycol; triethyl citrate; and triethylene glycol diacetate. In some embodiments, the filter material removes from about 50% to about 90% phenol from tobacco smoke.

In some embodiments, the filter material removes from about 50% to about 90% cresol from tobacco smoke.

According to a second aspect of the invention, process for preparing filter material for inclusion in a smoking article is provided, the filter material comprising fibres which comprise cellulose acetate and polyethylene oxide, the process comprising

electrospinning or centrifugal spinning of a solution comprising cellulose acetate and polyethylene oxide, or melt spinning a mixture comprising cellulose acetate and polyethylene oxide.

In some embodiments, the solution has a cellulose acetate concentration of from about 6% to about 30%.

In some embodiments, the solution has a polyethylene oxide concentration of from about 1% to about 20% by weight of the cellulose acetate. In some embodiments, the fibres comprising cellulose acetate and polyethylene oxide are produced by spinning the solution through a spinneret using centrifugal force, and the spinneret spins at a rate of from about 4500 to about 7500 rpm.

In some embodiments, the flow rate of the solution through the orifice(s) of the spinneret is from about 5 to about 100 ml/min.

In some embodiments, the fibres comprising cellulose acetate and polyethylene oxide are laid down as a non-woven sheet or non-woven web directly following spinning. In some embodiments, the fine cellulose acetate fibres are drawn onto a base sheet upon which a non-woven sheet or web is formed by a vacuum pull, by air flow or by electrostatic charge.

According to a third aspect of the invention, filter material is provided, obtained or obtainable by a process according to the second aspect. According to a fourth aspect, a filter element or filter for a smoking article is provided, comprising a filter material according to the first aspect, or comprising a filter material obtained or obtainable by a process according to the second aspect.

In some embodiments, the filter has a pressure drop of from about 60 to about 140 mmWG.

In some embodiments, the filter comprises from about 10 to about 100 mg of filter material in the form of a fibrous tow or a non-woven sheet comprising fibres comprising cellulose acetate and polyethylene oxide.

In some embodiments, the fibres comprising cellulose acetate and polyethylene oxide have a mean width of from about 1 μπι to about 15 μπι

In some embodiments, the filter comprises from about 30 to about 90 mg of said filter material.

According to a fifth aspect of the invention, a smoking article is provided, comprising a filter or filter element according to the fourth aspect.

According to a sixth aspect of the invention, there is provided use of the filter material according to the first or third aspect, in the filtration of tobacco smoke.

Brief Description of the Figures

In order that aspects of the invention may be more fully understood, embodiments thereof are described, by way of illustrative example, with reference to the

accompanying drawings in which:

Figure 1 is a schematic side view of a smoking article including a filter according to some embodiments.

Figure 2, 3 and 4 are SEMs showing filter material according to some embodiments. Detailed Description

Most commercial cigarette filters are made from cellulose acetate (CA) fibres or "tow". This CA tow, which is used as cigarette filter material in many commercially available filter cigarettes, is referred to herein as "conventional" cellulose acetate. Conventional CA typically has a degree of substitution of less than 3.0, preferably in the range of 2.2 to 2.8, and most preferably in the range of 234 to 2.5.

The filaments of conventional CA tow have a diameter of approximately 20 μπι. The filaments of conventionally used CA tow generally have a Y cross section, but it is known to make filaments with other cross-sectional shapes, including crenulated, X, and I (or "dog bone").

The amount of filter tow in the filter rod (associated with a parameter called "tow weight") determines the density of the filter rod. The firmness of the filter rod can be controlled by adding a so-called "plasticizer", for example glycerol triacetate, usually referred to as triacetin. The plasticizer actually acts as a binder, binding adjacent fibres at their points of contact. This results in an increase the hardness or structural rigidity of the rod formed from the tow.

Routinely measured filter parameters include pressure drop and 'tar' or NFDPM (nicotine-free dry particulate matter) or nicotine filtration efficiency and these parameters are related. Pressure drop (also referred to as "draw resistance") determines the amount of suction a smoker needs to apply to the cigarette to draw smoke through the filter. The pressure drop of the filter plus that of the tobacco column must be within a range acceptable to consumers, which is typically approximately 80-160 mm water gauge (WG). The pressure drop will be affected by the physical properties of the filter material, such as fibre diameter and cross-sectional shape. In addition, it will be affected by the manner in which the filter material is incorporated into the filter. For example, the packing density of the filter material within the filter will affect the pressure drop.

Filtration efficiency refers to the proportion of the material retained by the filter compared with that entering it. The filtration efficiency is affected by the smoke flow velocity and is typically determined using a standard machine-smoking regime. The main purpose of a cigarette filter is to reduce the particulate smoke yield which is achieved by mechanical filtration of aerosol particles. Herein, the filtration efficiency is measured taking puffs of 35 ml volume and of a 2 second at 60 second intervals with the ventilation zone blocked. Removal of specific constituents of the particulate phase is generally in proportion to the "tar" filtration efficiency. Gas phase smoke passes through cellulose acetate filters largely unaffected. Some semi-volatile constituents, e.g. phenolic species, can be selectively retained by conventional CA tow and this selective retention may be further enhanced by certain plasticizers. When used to filter cigarette smoke, conventional cellulose acetate tow has been shown to selectively remove phenol, cresol and pyridine.

The inventors have surprisingly found that spinning cellulose acetate fibres from a cellulose acetate solution comprising polyethylene oxide (PEO) produces fibres having an increased surface area to volume ratio compared to fibres produced in the absence of the PEO. More specifically, the fibres produced by spinning a cellulose acetate and PEO solution have a flattened cross sectional shape. The increased surface area to volume ratio of the flattened cellulose acetate fibres means that these fibres may be incorporated into filter material which results in greater than expected selective phenol reduction from tobacco smoke.

As used herein, "flattened cellulose acetate fibres", "flattened fibres" or "flattened CA fibres" are fibres produced by spinning a cellulose acetate and PEO solution and having a flattened cross sectional shape.

Therefore, in one aspect of the invention, a filter material for inclusion in a smoking article is provided, the filter material comprising fibres which comprise cellulose acetate and polyethylene oxide. In some embodiments, the filter comprises flattened cellulose acetate fibres.

Polyethylene glycol (PEG), polyethylene oxide (PEO) and polyoxyethylene (POE) are all oligomers or polymers of ethylene oxide. The three names are chemically synonymous, but PEG is generally used to refer to oligomers and polymers with a molecular mass below 20,000 g/mol, whilst PEO refers to polymers with a molecular mass above 20,000 g/mol and POE refers to polymers of any molecular mass. PEG and PEO may be liquids or low-melting solids at room temperature, depending on their molecular weights. The filter material may be in the form of a fibrous tow or a non-woven sheet, the tow or sheet comprising cellulose acetate fibres comprising cellulose acetate and polyethylene oxide. In some embodiments, the fibrous tow or non-woven sheet comprises flattened cellulose acetate fibres.

In some embodiments, the fibres have a ribbon-like morphology, or their cross sectional shape is a flattened circle or an ellipse. Both of these morphologies are referred to herein as "flattened". In some embodiments, the flattened fibres have an aspect ratio of greater than i:i and generally of at least about 2.5:1 or at least about 5:1.

In some embodiments, the flattened fibres may have a mean width of from about 1 μπι to about 15 μπι as determined by Scanning Electron Microscopy (SEM).

In some embodiments, the mean width is calculated based upon the number of fibres. In other embodiments, the mean width is calculated based upon the mass of fibres.

As used herein, "fine fibres", "fine cellulose acetate fibres" or "fine CA fibres" are cellulose acetate fibres having a mean width of from about 1 μπι to about 15 μπι, or from about 1 μπι to about 10 μπι.

In some embodiments, the filter material, i.e. the tow or non-woven sheet, is formed from fibres and at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 97%, at least about 98%, at least about 99%, at least about 99.5%, or at least about 99.8% by weight of the fibres are flattened cellulose acetate fibres.

Alternatively or in addition, in some embodiments, the filter material may comprise at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 97%, at least about 98%, at least about 99%, at least about 99.5%, or at least about 99.8% by volume flattened cellulose acetate fibres. some embodiments, the filter material may comprise at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 97%, at least about 98%, at least about 99%, at least about 99.5%, or at least about 99.8% by surface area flattened cellulose acetate fibres.

The tow or non-woven sheet may consist of the flattened cellulose acetate fibres or may consist essentially of the flattened cellulose acetate fibres.

In some embodiments, the tow or sheet is formed directly using the flattened cellulose acetate fibres, without the need to first form the flattened fibres into filaments, for example by spinning or a similar process. This may be true even if the flattened cellulose acetate fibres are fine fibres. Thus, the tow or non-woven sheet is made up of individual flattened fibres.

In some embodiments, individual flattened fibres may have a sufficiently large width so that they do not dissolve when in use, for example when filtering tobacco smoke. In some embodiments, the fine cellulose acetate fibres have a width of no less than 0.5 μπι or no less than 0.3 μπι.

Where the flattened fibres are in the form of tow, the tow is made directly from the fibres of cellulose acetate, rather than being formed of filaments created from flattened cellulose acetate fibres.

The flattened cellulose acetate fibres comprise or consist of cellulose acetate and PEO. In some embodiments, the fibres comprise cellulose acetate, PEO and any additives or the like used in their manufacture and/or used in the manufacture of the filter material, such as a tow or non-woven sheet.

For example, in some embodiments, the fibres are formed from a cellulose acetate and PEO solution which may include an additive, for example which may act as a lubricant and/ or may help to control the rate of evaporation of the solvent during the formation of the fibres. Some of the additive may be present in the flattened fibres produced in such as way.

In some embodiments, the flattened fibres include at least about 0.1%, at least about 0.5%, at least about 1%, at least about 2%, at least about 5%, at least about 10%, or at least about 15% of PEO by weight of the flattened fibres. Additionally or alternatively, in some embodiments, the flattened fibres include up to about 50%, up to about 40%, up to about 30%, up to about 25%, up to about 20%, up to about 15%, up to about 10%, up to about 5% or up to about 2% of PEO by weight of the flattened fibres. In some of these embodiments, the flattened fibres consist of or consist essentially of cellulose acetate and PEO.

In some embodiments, flattened fibres include at least about 0.1%, at least about 0.5%, at least about 1%, at least about 2%, at least about 5%, at least about 10%, or at least about 15% of an additive by weight of the flattened fibres. Additionally or alternatively, in some embodiments, the flattened fibres include up to about 20%, up to about 15%, up to about 10%, up to about 5% or up to about 2% of an additive by weight of the flattened fibres.

In some embodiments, the filter material includes at least about 0.1%, at least about 0.5%, at least about 1%, at least about 2%, at least about 5%, at least about 10%, or at least about 15% of an additive by weight of the filter material. Additionally or alternatively, in some embodiments, the filter material includes up to about 20%, up to about 15%, up to about 10%, up to about 5% or up to about 2% of an additive by weight of the filter material. In some embodiments, the flattened fibres may comprise at least about 50%, at least about 60%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 97%, at least about 98%, at least about 99% by weight cellulose acetate. After manufacture of the flattened fibres, the filter material may be treated with other additives, such as plasticizers. Such additives which are added to the fibres will generally not be considered to form part of the fibres themselves.

In some embodiments, the plasticizer is one or more selected from the group consisting of: triacetin; polyethylene glycol (PEG); triethyl citrate (TEC); and triethylene glycol diacetate (TEGDA).

In some embodiments, the filter material includes at least about 0.1%, at least about 0.5%, at least about 1%, at least about 2%, at least about 5%, at least about 10%, or at least about 15% plasticizer by weight of the filter material. Additionally or alternatively, in some embodiments, the filter material includes up to about 20%, up to about 15%, up to about 10%, up to about 5% or up to about 2% plasticizer by weight of the filter material.

In some embodiments, the filter material may comprise at least about 50%, at least about 60%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 97%, at least about 98%, at least about 99% by weight cellulose acetate.

The filter material may have an acceptable and/ or desirable filtration efficiency. The filter material may have an acceptable and/ or desirable filtration efficiency for the filtration of an aerosol such as tobacco smoke.

It has been found that the filter material according to the invention provides at least the same filtration efficiency per gram of filter material as conventional cellulose acetate tow. Indeed, in many embodiments, the filtration efficiency of the filter material of the invention is greater per gram of filter material than that of conventional cellulose acetate. This allows less filter material to be used whilst achieving the same filtration effect. In some embodiments, an acceptable filtration efficiency for the filtration of tobacco smoke may be the removal of at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, or at least about 50% nicotine-free dry particulate matter (NFDPM). In some embodiments, an acceptable filtration efficiency for the filtration of tobacco smoke may be the removal of at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, or at least about 50% nicotine.

In some embodiments, the filter material of the invention removes at least about 60%, at least about 70%, at least about 75% or at least about 80% of the NFDPM. In some embodiments, the filter material of the invention removes at least about 60%, at least about 70%, at least about 75% or at least about 80% of the nicotine.

It has further been shown that the fine fibre cellulose acetate filter material exhibits increased phenol selectivity compared to conventional cellulose acetate tow. In some embodiments, the filter material of the invention removes from about 50% to about 90% phenol from tobacco smoke. In some embodiments, the filter material of the invention removes from about 50% to about 90% cresol from tobacco smoke.

Thus, the filter material of the invention exhibits greater selectivity for phenol and cresol than conventional cellulose acetate tow (as shown in the Examples below).

PEO can be used to flatten the shape of a CA fibre thereby changing the filtration characteristics and adding selectivity towards phenol and cresol filtration.

Processes

In order to form fibres from cellulose acetate, the cellulose acetate may be dissolved in acetone to produce a solution which is then extruded by being forced out through one or more orifices to form fibres. Frequently, it will be desirable to filter the cellulose acetate solution before it is extruded.

Spinning is the basic technique used for forming fibres from substances in solution, such as cellulose acetate. The solution is generally forced through a cap or nozzle, called a spinneret. The spinneret is perforated with small holes and a filament is extruded through each one. A spinneret may have from one to several hundred or even thousand holes. As the filaments emerge from the holes in the spinneret, the liquid polymer is converted first to a rubbery state and then solidified. This process of extrusion and solidification of endless filaments is called spinning (however, it should not be confused with the process used to combine multiple fibres into a filament, which is also called spinning).

Solidification of the extruded polymer is achieved by evaporating the solvent in a stream of warm air or inert gas.

While extruded fibres are solidifying, or in some cases even after they have hardened, the filaments may be drawn to impart strength. Drawing pulls the molecular chains together and orients them along the fibre axis, creating considerably stronger fibres. This can also reduce the diameter of the fibres. Following the exiting of the cellulose acetate from the spinneret, there may be rapid evaporation of the solvent from the surface of the extruded filament. This leads to the formation of a skin layer on the surface. As the solvent from within the body of the filament subsequently evaporates, the skin layer on the surface caves in, providing the fibre with a cross section having a collapsed shape. It is hypothesised that it is the rapid evaporation of the solvent as a result of the presence of the PEO in the feedstock (i.e. in the solution of cellulose acetate which is spun) that results in the formation of flattened fibres. The filter material of the invention is made by a spinning process, in which the cellulose acetate concentration of the solution, the orifice size and/or the flow rate of the polymer solution through the spinneret may be controlled to provide fibres having a desired mean width. In some embodiments, the desired width of the flattened fibres is from about ι μπι to about 15 μπι.

In some embodiments, the spinning is controlled to provide finer fibres than seen in conventional cellulose acetate tow. In some embodiments, this may be as a result of utilising electrostatic charge to draw out the fibres (electrospinning), or utilising high velocity air flow to blow the fibres, or by utilising centrifugal force to draw out the fibres from liquid feed stock, or by melt spinning.

In embodiments where the fibres of cellulose acetate are produced by melt spinning, the cellulose acetate is heated to a temperature at which it has a desired viscosity for the process.

In some embodiments where the fibres of cellulose acetate are produced by other spinning processes, the fibres are made from a cellulose acetate solution. In some embodiments, the cellulose acetate solution, formed from cellulose acetate in acetone, has a cellulose acetate concentration of from about 6% to about 30%, from about 7% to about 25% or from about 8% to about 20%.

In some embodiments, the cellulose acetate feedstock being spun (whether a solution or in molten state) includes PEO in an amount so that the ratio of cellulose acetate to PEO is from about 99:1 to about 50:50, or from about 95:5 to about 80:20. In some embodiments, the feedstock may be heated during spinning, for example to prevent gelling and the consequent clogging of the orifices that can be observed with some cellulose acetate solutions. For example, the temperature of the feedstock being spun may be from about room temperature (for example 20°C or 25°C) to about 6o°C.

In embodiments where the flattened fibres are produced by spinning using centrifugal force, the spinneret may spin at a rate of from about 4500 to about 7500 rpm, or from about 5000 to about 7000 rpm. In some embodiments, the flow rate of the feedstock, i.e. of the cellulose acetate solution, through the orifice(s) of the spinneret is from about 5 to about 100 ml/min, or from about 10 to about 50 ml/min. In some embodiments, these flow rates may be used in combination with the spin rates mentioned above for centrifugal force spinning. In some embodiments, the flattened fibres are laid down as a non-woven sheet or non- woven web directly following spinning. In some embodiments, the fibres are drawn to a base sheet upon which the non-woven sheet is formed by a vacuum pull, by air flow or by electrostatic charge. In some embodiments, the non-woven sheets have a basis weight or grammage of from about 5 to about 50 g/m² (also referred to as gsm), or from about 10 to about 40 g/m², or from about 15 to about 35 g/m².

In some embodiments, the non-woven sheets have a caliper of from about 100 to about 1500 μπι, or from about 250 to about 750 μπι.

In some embodiments, centrifugal spinning is used to produce the flattened fibres. The orifices of the spinneret used to produce the flattened fibres are round. The round orifices may be used to produce fibres with a ribbon-like shape, being substantially flat and having a very large aspect ratio.

Filters and smoking articles

The filter material may be incorporated into a smoking article, or a part thereof. In some embodiments, a filter or filter element containing the filter material is

incorporated into a smoking article. The filter material, filter or filter element may be incorporated into a smoking article by any method known in the art. As used herein, the term "smoking article" includes smokeable products such as cigarettes, cigars and cigarillos whether based on tobacco, tobacco derivatives, expanded tobacco, reconstituted tobacco or tobacco substitutes and also heat-not-burn products. In addition, in some embodiments, the term "smoking article", as used herein, further encompasses aerosol generation devices, such as e-cigarettes and other nicotine inhalers, as well as inhalation devices such as so-called "heat-not-burn" devices in which tobacco is heated but not combusted. Referring to Figure 1, a smoking article 1 according to an embodiment of the invention comprises a filter 2 and a cylindrical rod of smokeable material 3, such as tobacco, aligned with the filter 2 such that one end of the smokeable material rod 3 abuts the end of the filter 2. The filter 2 is wrapped in a plug wrap (not shown) and the smokeable material rod 3 is joined to the filter 2 by tipping paper in a conventional manner. The filter 2 is substantially cylindrical and has a mouth end 4 and a smokeable material end 5. The filter 2 comprises filter material 6 as described herein.

Because of the enhanced filtration characteristics of the flattened CA fibres, it is possible to achieve an equivalent or improved filtration compared to that of a conventional CA filter using less filter material. This means that less filter material needs to be used. In some embodiments, it may be desirable to make the filter to the same dimensions as used in a conventional cigarette design, namely having a target length of 144 mm and a target circumference of 24.3 mm. In other embodiments, the filters may be for use in smoking articles of other formats, such as so-called super-slim or demi-slim, the filters will have different dimensions.

When incorporated into a filter or filter element, the filter material may confer desirable physical properties. For example, pressure drop across the filter or filter element may be between 60 and 140 mmWG, which would be a desirable pressure drop when the filter or filter element is incorporated into a smoking article.

In some embodiments, a filter comprising the filter material of the invention may have a pressure drop of from about 60 to about 140 mmWG, from about 70 to about 130 mmWG, from about 75 to about 120 mmWG, from about 80 to about 110 mmWG, from about 85 to about 100 mmWG, or from about 90 to about 95 mmWG. In some embodiments, a filter comprising the filter material of the invention may include filter material having a weight of from about 30 to about 90 mg, or from about 40 to about 80 mg. This is compared to a conventional cellulose acetate filter (of a so- called king-size format) in which approximately 120 to 130 mg of the cellulose acetate tow is included. For alternative filter formats, for example in those for use in a super- slim of demi-slim smoking article, the amount of filter material used would obviously be reduced.

In embodiments where less filter material of the invention is incorporated in a filter having a conventional shape and dimensions, this may mean that the filter is less densely packed with the filter material. In other embodiments, the filter may be designed so that the filter material is present in only part of the filter rod, for example in a central axial rod surrounded by a void or by other material. In such embodiments it may be desirable to ensure that the flow path of the mainstream smoke being drawn through the filter rod is channelled through the filter material. In alternative embodiments, the flow path may be variable. In an alternative approach, the filter may have one or more cavities. Such cavities may have essentially the same diameter as the filter material plug. For example, such a cavity may be formed between two plugs of filter material, or between one plug of filter material and the rod of smokeable material. In some embodiments, the cavity may house filter components such as adsorbent material, flavourants or additive release components.

In some embodiments, the filter material has an acceptable and/or desirable filtration efficiency and an acceptable and/or desirable pressure drop when in use, for example when the filter material is incorporated into a smoking article.

Examples

The flattened fibre cellulose acetate filter materials used in the experiments of the examples set out below were produced by centrifugal spinning of a cellulose acetate and PEO solution. The concentration and the spinning of the spinneret were adjusted to obtain fibres of the desired mean diameter. The fibres were deposited on a substrate sheet and removed to provide non-woven sheets of flattened cellulose acetate fibres.

The images of Figures 2, 3 and 4 show the flattened fibres resulting from the centrifugal spinning of three different samples. The cellulose acetate concentration of the feedstock was varied, using 7% and 14% solutions. In addition, the amount of PEO in the solution was also varied, using a ratio of cellulose acetate to PEO of 95:5 and 80:20. The SEMS show that the different solutions produced flattened fibres. The higher the cellulose acetate concentration, the greater the viscosity of the solution being spun and the greater the width of the fibres produced. Increasing the PEO content appears to increase the rate at which the solvent (acetone) evaporates once the solution has exited the orifice. Therefore, the greater the concentration of PEO, the flatter the fibres.

In order to address various issues and advance the art, the entirety of this disclosure shows by way of illustration various embodiments in which the claimed invention(s) may be practiced and provide for superior filter materials. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and/ or exclusive. They are presented only to assist in understanding and teach the claimed features. It is to be understood that advantages, embodiments, examples, functions, features, structures, and/or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and

modifications may be made without departing from the scope and/ or spirit of the disclosure. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. In addition, the disclosure includes other inventions not presently claimed, but which may be claimed in future.

Claims

1. A filter material for inclusion in a smoking article, wherein the filter material comprises fibres which comprise cellulose acetate and polyethylene oxide.

2. A filter material as claimed in claim 1, wherein the fibres comprising cellulose acetate and polyethylene oxide have a flattened cross sectional shape.

3. A filter material as claimed in claim 1 or claim 2, wherein the fibres comprising cellulose acetate and polyethylene oxide have a mean width of from about 1 μπι to about

15 μπι.

4. A filter material as claimed in any one of the preceding claims, wherein the filter material is in the form of a tow or non-woven sheet is formed from fibres and at least about 80% by weight of the fibres are fibres which comprise cellulose acetate and polyethylene oxide.

5. A filter material as claimed in any one of the preceding claims, wherein the fibres comprise cellulose acetate, polyethylene oxide and an additive.

6. A filter material as claimed in any one of the preceding claims, wherein filter material further comprises a plasticizer which is one or more selected from the group consisting of: triacetin; polyethylene glycol; triethyl citrate; and triethylene glycol diacetate.

7. A filter material as claimed in any one of the preceding claims, wherein the filter material removes from about 50% to about 90% phenol from tobacco smoke.

8. A filter material as claimed in any one of the preceding claims, wherein the filter material removes from about 50% to about 90% cresol from tobacco smoke.

9. A process for preparing filter material for inclusion in a smoking article, the filter material comprising fibres which comprise cellulose acetate and polyethylene oxide, the process comprising electrospinning or centrifugal spinning of a solution comprising cellulose acetate and polyethylene oxide, or melt spinning a mixture comprising cellulose acetate and polyethylene oxide.

10. A process as claimed in claim 9, wherein the solution has a cellulose acetate concentration of from about 6% to about 30%.

11. A process as claimed in claim 9 or claim 10, wherein the solution has a polyethylene oxide concentration of from about 1% to about 20% by weight of the cellulose acetate.

12. A process as claimed in any one of claims 9 to 11, wherein the fibres comprising cellulose acetate and polyethylene oxide are produced by spinning the solution through a spinneret using centrifugal force, and the spinneret spins at a rate of from about 4500 to about 7500 rpm.

13. A process as claimed in any one of claims 9 to 12, wherein the flow rate of the solution through the orifice(s) of the spinneret is from about 5 to about 100 ml/min.

14. A process as claimed in any one of claims 9 to 13, wherein the fibres comprising cellulose acetate and polyethylene oxide are laid down as a non-woven sheet or non- woven web directly following spinning.

15. A process as claimed in claim 14, wherein the fine cellulose acetate fibres are drawn onto a base sheet upon which a non-woven sheet or web is formed by a vacuum pull, by air flow or by electrostatic charge.

16. A filter material obtained or obtainable by a process as claimed in any one of claims 9 to 15.

17. A filter element or filter for a smoking article, comprising a filter material as claimed in any one of claims 1 to 8, or comprising a filter material obtained or obtainable by a process as claimed in any one of claims 9 to 15.

18. A filter as claimed in claim 17, wherein the filter has a pressure drop of from about 60 to about 140 mmWG.

19. A filter as claimed in claim 17 or claim 18, comprising from about 10 to about 100 mg of filter material in the form of a fibrous tow or a non-woven sheet comprising fibres comprising cellulose acetate and polyethylene oxide.

20. A filter as claimed in claim 19, wherein the fibres comprising cellulose acetate and polyethylene oxide have a mean width of from about 1 μπι to about 15 μπι

21. A filter as claimed in claim 19 or claim 20, comprising from about 30 to about 90 mg of said filter material.

22. A smoking article comprising a filter or filter element as claimed in any one of claims 17 to 21.

23. Use of the filter material as claimed in any one of claims 1 to 8 or 16 in the filtration of tobacco smoke.