US20220079217A1

US20220079217A1 - Filter For Smoking or Vaping Article Comprising a Nonwoven Substrate

Info

Publication number: US20220079217A1
Application number: US17/471,864
Authority: US
Inventors: Oxana Cherkas; Diane M. Raverdy-Lambert
Original assignee: SWM Luxembourg SARL; Schweitzer Mauduit International Inc
Current assignee: SWM Services SAS; SWM Luxembourg SARL; Mativ Holdings Inc
Priority date: 2020-09-11
Filing date: 2021-09-10
Publication date: 2022-03-17
Also published as: KR20230068414A; FR3114009B1; CN116056593A; EP4210518A1; CA3191611A1; AU2021339948A1; WO2022053625A1; JP2023541885A; FR3114009A1; AU2021339948A8

Abstract

The present invention relates to a filter comprising a nonwoven substrate having a low density and comprising natural fibers and a binder. The filter can be used as a filter for a smoking or vaping article.

Description

TECHNICAL FIELD

A subject of the invention is a filter comprising a nonwoven substrate having a low density and comprising natural fibers and a binder. This nonwoven substrate is capable of being obtained by a drylaid process. This filter can be used as filter for a smoking or vaping article.

PRIOR ART

A filter for a smoking or vaping article has a right circular cylindrical shape and generally comprises an outer envelope of plug wrap paper and a substrate located within the outer envelope. The filter for a smoking or vaping article, by virtue of the substrate, makes it possible to prevent the user from inhaling tobacco particles and allows retention of the harmful particulate substances contained in the smoke or the aerosol, such as tar.
Filters are commonly made from cellulose acetate. These cellulose acetate filters have a nicotine retention capacity such that the user's perception of the filtered smoke is satisfactory. In addition, these filters generate a filtered smoke having good organoleptic properties. However, these cellulose acetate substrates degrade very slowly and are not dispersible in water. This is particularly harmful since the filter is not consumed during the smoking/vaping of a smoking/vaping article and is regularly found in the environment. Cellulose acetate substrates thus have a significant environmental impact.
To limit the environmental impact of conventional filters, it has been proposed to replace the cellulose acetate with paper. As paper substrates are biodegradable, they degrade rapidly. However, the nicotine retention capacity of filters comprising a paper substrate is such that the user's perception of the filtered smoke may not be satisfactory. In addition, the smoke filtered by filters comprising a paper substrate may have a drying taste which is unsatisfactory for the user. The user experience provided by these paper substrates is thus not as satisfactory when compared with cellulose acetate.

Technical Problem

There is therefore a need for a filter which has a nicotine retention capacity of the same order of magnitude as that of a filter comprising a cellulose acetate substrate, which provides a satisfactory user experience.
It is thus to the credit of the inventors to have found that it was possible to meet this need by means of a nonwoven substrate.

SUMMARY

It is proposed a filter comprising a nonwoven substrate comprising natural fibers and a binder, in which the natural fibers represent between 70% and 99%, in particular between 80% and 98%, very particularly between 85% and 98% by weight of solids of said nonwoven substrate, the binder represents between 1% and 30%, in particular between 2% and 20%, very particularly between 2% and 15% by weight of solids of said nonwoven substrate, and characterized in that the nonwoven substrate has a density of between 7 mg/cm³and 60 mg/cm³, in particular between 8 mg/cm³and 50 mg/cm³, very particularly between 10 mg/cm³and 40 mg/cm³.
Advantageously, the filter of the invention has a nicotine retention capacity of the same order of magnitude as the retention capacities of a filter comprising a cellulose acetate substrate. Consequently, the user's perception of the smoke filtered by the filter of the invention is satisfactory.
Moreover, the smoke filtered by the filter of the invention has organoleptic properties which are satisfactory for the user.
The nonwoven substrate can also make it possible to produce the filter of the invention without a prior shaping step, which is not the case for paper substrates. Thus, the process for producing the filter of the invention is simplified.
According to another aspect, a process is proposed for producing the filter of the invention comprising a nonwoven substrate, said process comprising the following steps:

- a) forming a rod of nonwoven substrate from a nonwoven substrate,
- b) wrapping the rod of nonwoven substrate with a sheet of plug wrap paper,
- c) depositing an adhesive line, joining the sheet of plug wrap paper to obtain a rod of filtering material,
- d) cutting the rod of filtering material to produce the filter.
  wherein the nonwoven substrate is as defined above or is obtained by a process comprising the following steps:
- i) producing a web from natural fibers by a drylaid process,
- ii) introducing the binder into the web, and
- iii) drying the web resulting from step ii) to obtain the nonwoven substrate.

DESCRIPTION OF THE EMBODIMENTS

It is proposed a filter comprising a nonwoven substrate comprising natural fibers and a binder, in which the natural fibers represent between 70% and 99%, in particular between 80% and 98%, very particularly between 85% and 98% by weight of solids of said nonwoven substrate, the binder represents between 1% and 30%, in particular between 2% and 20%, very particularly between 2% and 15% by weight of solids of said nonwoven substrate;
characterized in that the nonwoven substrate has a density of between 7 mg/cm³and 60 mg/cm³, in particular between 8 mg/cm³and 50 mg/cm³, very particularly between 10 mg/cm³and 40 mg/cm³.
Compared to the conventional density of paper substrates, which is greater than 300 mg/cm³, the density of the nonwoven substrate is very low.
Without wishing to be bound by any theory, the inventors are of the opinion that, by virtue of this low density, the nonwoven substrate of the filter of the invention has a higher filter filling power than the filling power of a paper substrate. This higher filling power makes it possible to reduce the amount of nonwoven substrate present in the filter such that the filter of the invention has a nicotine retention capacity of the same order of magnitude as the retention capacity of a filter comprising a cellulose acetate substrate.
For the purposes of the present application, “nonwoven substrate” (also referred to as “non-woven substrate”) denotes a manufactured sheet consisting of a web or ply of directionally or randomly oriented fibers bonded together by friction and/or cohesion and/or adhesion.
Typically, the density of the nonwoven substrate is calculated by dividing its grammage by its thickness.
The standard ISO 536:2012 can be used to determine the grammage of the nonwoven substrate. The substrate is conditioned for at least 16 hours at 23° C. and 50% humidity before the measurement.
To measure the thickness of the nonwoven substrate, it is possible to use a dead-weight micrometer comprising a 25 cm²measuring head with two planar, parallel and circular pressure surfaces. During the measurement, the nonwoven substrate is placed between the two pressure surfaces for 10 seconds. The pressure exerted between the pressure surfaces during the measurement of the thickness is 0.5 kPa. The substrate is conditioned for at least 16 hours at 23° C. and 50% humidity before the measurement.
The grammage of the nonwoven substrate of the filter of the invention can for example be between 20 g/m²and 60 g/m², in particular between 23 g/m²and 57 g/m², more particularly between 25 g/m²and 55 g/m².
The thickness of the nonwoven substrate of the filter of the invention can for example be between 700 μm and 6000 μm, in particular between 1000 μm and 4700 μm, more particularly between 2000 μm and 4500 μm.
According to one particular embodiment, the nonwoven substrate can have a density of between 10 mg/cm³and 40 mg/cm³, and a thickness of between 2000 μm and 4500 μm.
The person skilled in the art will know how to adapt the grammage and the thickness of the nonwoven substrate in order to achieve the desired density.
For the purposes of the present application, the term “natural fiber” denotes a fiber of natural origin which has optionally undergone a chemical treatment, a physical treatment, or both, in order to optimize the physical characteristics thereof.
For example, the natural fibers can be chosen from wood fibers, leaf fibers, fruit fibers, seed fibers, bast fibers, stalk fibers, reed fibers, and mixtures thereof, in particular wood fibers, leaf fibers, seed fibers, bast fibers, and mixtures thereof, more particularly wood fibers, bast fibers and mixtures thereof.
Examples of wood fibers which may be present in the nonwoven substrate of the filter of the invention can be lyocell fibers (cellulose fibers which are ground and dissolved in N-methylmorpholine N-oxide monohydrate for the purpose of obtaining fibers with a cross section of variable shape (round, oval, cross-shaped, circular, lamellar cross section) with calibrated length and mass per unit length, which the person skilled in the art can choose depending on their needs), viscose fibers (fibers obtained by dissolving cellulose by means of modification of its hydroxyl groups by carbon disulfide (CS₂) and then its precipitation in the presence of sulfuric acid (H₂SO₄) for the purpose of obtaining fibers with a cross section of variable shape (round, oval, cross-shaped, circular, lamellar cross section) with calibrated length and mass per unit length, which the person skilled in the art can choose depending on their needs), and mixtures thereof, in particular lyocell fibers, viscose fibers, and mixtures thereof.
For the purposes of the present application, “bast fiber” denotes a plant fiber contained in the bast of the plants.
As bast fiber, mention may be made of hemp fiber, Indian hemp fiber, jute fiber, kenaf fiber, kudzu fiber, flax fiber, okra fiber, nettle fiber, ramie fiber, and mixtures thereof, in particular hemp fiber, flax fiber, and a mixture thereof, more particularly flax fiber.
Typically, the bast fibers may have undergone prior treatment. Thus, the bast fibers may be cottonized bast fibers, individualized bast fibers, bast fibers which have undergone retting, bleached bast fibers, and mixtures thereof, in particular cottonized bast fibers, individualized bast fibers and a mixture thereof.
For the purposes of the present application, “seed fiber” denotes a fiber obtained from seeds of a plant. Examples of seed fibers can be cotton fiber, kapok fiber, luffa fiber, milkweed fiber, and mixtures thereof, in particular kapok fiber.
According to one particular embodiment, the natural fibers are chosen from lyocell fibers, flax fibers, cottonized flax fibers, cotton fiber and mixtures thereof, in particular a mixture of cottonized flax fibers and lyocell fibers.
According to one particular embodiment, the natural fibers of the nonwoven substrate can be a mixture of natural fibers comprising cottonized flax fibers and lyocell fibers,
the cottonized flax fibers represent more than 50%, in particular between 70% and 98%, more particularly between 85% and 95% by weight of solids of said mixture of fibers, and
the lyocell fibers representing less than 50%, in particular between 2% and 30%, more particularly between 5% and 15% by weight of solids of said mixture of fibers.
According to the invention, the natural fibers, before use in the nonwoven substrate, can have a length of between 10 mm and 150 mm, in particular between 15 mm and 100 mm, more particularly between 20 mm and 60 mm.
A drylaid process is particularly suitable for this size of natural fibers. Thus, the nonwoven substrate of the filter of the invention of this alternative embodiment can be obtained by a drylaid process.
The length of the natural fibers can be measured by a Classifiber KCF-V/LS apparatus from Keisokki. Natural fibers are combed and individualized before measurement. The sizes of the fibers are measured automatically by an optical method.
The natural fibers may also be cut so as to have a length within the ranges mentioned above. Conventional cutting techniques which can be used are guillotine cutting of natural fibers, grinding of the natural fibers with or without a system for removing excessively short and excessively long fibers of air cyclone or screen type.
For the purposes of the present application, “binder” denotes a compound having properties enabling consolidation of the nonwoven substrate.
For example, the binder can be a natural polymer, a synthetic polymer or copolymer or a mixture thereof. The natural polymer can be a polysaccharide, a cellulose derivative, or a mixture thereof. The synthetic polymer can be a latex.
The polysaccharide which can be used as binder can be a polysaccharide or a polysaccharide derivative. For example, starch, dextrin, gum arabic, and mixtures thereof can be used as binder, in particular starch.
For example, the cellulose derivative can be chosen from ethyl cellulose, methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, an alkali metal salt of carboxymethyl cellulose, and mixtures thereof, in particular carboxymethyl cellulose.
As alkali metal of the carboxymethyl cellulose salt, mention may be made of potassium, sodium, and magnesium.
The synthetic polymer or copolymer can, for example, be a polyvinyl alcohol, an ethylene-vinyl alcohol, a polyvinyl acetate, a polyvinyl chloride, a styrene-butadiene, a polybutadiene, polyacrylics, an ethylene-vinyl acetate, and mixtures thereof, in particular polyvinyl alcohol.
According to another very particular embodiment, the nonwoven substrate can comprise:
a mixture of fibers comprising between 85% and 95% of cottonized flax fibers by weight of solids of said mixture of fibers and between 5% and 15% of lyocell fibers by weight of solids of said mixture of fibers, and
a binder chosen from starch, polyvinyl alcohol, ethylene-vinyl acetate, which can represent between 2% and 15%, in particular between 2% and 8% by weight of solids of said nonwoven substrate,
in which the mixture of fibers can represent between 85% and 98%, in particular between 92% and 98% by weight of solids of said nonwoven substrate; and
can have a density of between 10 mg/cm³and 40 mg/cm³.
The nonwoven substrate of this other very particular embodiment can be obtained by a drylaid process.
The filter of the invention can be a filter for a smoking or vaping article.
For the purposes of the present application, “smoking article” denotes an article comprising tobacco and/or any other plant intended to be smoked. For example, the smoking article may be a machine-manufactured cigarette, a roll-your-own cigarette or a make-your-own cigarette.
Typically, the filter for a smoking article has a right circular cylindrical shape and comprises an outer envelope of plug wrap paper for a smoking article, in particular for a cigarette, and the nonwoven substrate of the filter of the invention as defined above located within the outer envelope.
For the purposes of the present application, “vaping article” denotes an article comprising tobacco and/or any other plant intended to be vaped, which is intended to be inserted into a device which heats the tobacco and/or the plant without burning said tobacco/plant and which enables delivery of an aerosol to a user. For example, the vaping article can be a tobacco stick.
Typically, the filter for a vaping article has a right circular cylindrical shape and comprises an outer envelope of plug wrap paper for a vaping article, in particular for a tobacco stick, and the nonwoven substrate of the filter of the invention as defined above located within the outer envelope.
The filter of the invention can have a density of between 100 mg/cm³and 200 mg/cm³, in particular between 110 mg/cm³and 170 mg/cm³, more particularly between 115 mg/cm³and 160 mg/cm³.
Typically, the density of the filter is measured after manufacture of the filters, by dividing the mass of the filter by its volume. For a filter having a right circular cylindrical shape, the volume of the filter (Vater) is calculated by the following formula: V_filter=π*L*r², in which r denotes the radius of the filter and L denotes the length of the filter.
The nonwoven substrate of the filter of the invention may not be crimped before the formation of the filter. This is highly advantageous since it makes it possible to produce a filter while simplifying the production of the filter.
According to another aspect, the present invention also relates to a smoking article comprising a filter as defined above.
According to another aspect, the present invention also relates to a vaping article comprising a filter as defined above.
The present invention also relates to the use of a nonwoven substrate as defined above in a filter, in particular a filter for a smoking article or a filter for a vaping article.
The present invention also relates to a process for producing a filter for a smoking or vaping article comprising a nonwoven substrate, said process comprising the following steps:

- a) forming a rod of nonwoven substrate from a nonwoven substrate,
- b) wrapping the rod of nonwoven substrate with a sheet of plug wrap paper,
- c) depositing an adhesive line, joining the sheet of plug wrap paper to obtain a rod of filtering material,
- d) cutting the rod of filtering material to produce the filter.
  wherein the nonwoven substrate is as defined above or is obtained by a process comprising the following steps:
- i) producing a web from natural fibers by a drylaid process, and
- ii) introducing the binder into the web,
- iii) drying the web resulting from step ii) to obtain the nonwoven substrate.

The nonwoven substrate, the natural fibers and the binder are as described above in relation to the nonwoven substrate.
In particular, the filter for a smoking or vaping article produced by the production process of the invention has a right circular cylindrical shape and comprises an outer envelope of plug wrap paper for a filter for a smoking or vaping article and the nonwoven substrate of the filter of the invention as defined above located within the outer envelope.
The nonwoven substrate of the filter of the invention can therefore be obtained by a drylaid process.
The drylaid process and the airlaid process are two different the conventional routes known to the person skilled in the art to produce a web. The person skilled in the art will know how to adapt the parameters of the drylaid process to produce the nonwoven substrate of the filter of the invention.
The process of the invention can comprise, if need be, before production step i), a step i1) of cutting the natural fibers to obtain natural fibers having a length within the ranges mentioned above.
Cutting step i1) can be carried out by conventional techniques such as guillotine cutting, grinding of the natural fibers with or without a system for removing excessively short and excessively long fibers of air cyclone or screen type.
During introduction step ii), an aqueous dispersion of the binder is introduced into the web. This introduction may for example be carried out by impregnation, such as impregnation with a size press, by spraying, such as spraying using a spray, by surface application, such as surface application by coating or by printing, in particular by spraying a spray. Advantageously, the spraying will be performed on both faces of the web.
The aqueous dispersion of the binder can be obtained by any technique known to the person skilled in the art. The person skilled in the art will know how to adapt the concentration of binder in the aqueous dispersion to obtain the desired content of binder in the nonwoven substrate of the filter of the invention.
Drying step iii) can, for example, be carried out by a drying device, such as a tunnel through which air passes or an infrared ramp.
This drying step iii) can be carried out at a temperature of between 75° C. and 200° C., in particular between 90° C. and 170° C., more particularly between 100° C. and 120° C. A temperature within these ranges advantageously makes it possible to minimize the duration of this drying step iii) while at the same time minimizing the deterioration of the natural fibers of the nonwoven substrate, thus optimizing the process of the invention.
Advantageously, the combination of the introduction step ii) and of the drying step iii) makes it possible to improve the cohesion of the natural fibers and hence to consolidate the structure of the nonwoven substrate of the filter of the invention.
The natural fibers used in production step i) can be a mixture of natural fibers. This mixture of natural fibers can be obtained before production step i).
The natural fibers can be bast fibers which have undergone prior treatment, such as cottonized bast fibers, individualized bast fibers, bast fibers which have undergone retting and mixtures thereof, in particular cottonized bast fibers, individualized bast fibers and mixtures thereof.
The process of the invention can thus comprise, before production step i), a step i2) of treating the bast fibers chosen from retting, bleaching, cottonizing, individualizing, and a mixture thereof, in particular cottonizing, individualizing or individualizing followed by cottonizing.
Cottonizing is a treatment in which the fibers are refined in order to pass through cotton mills. The person skilled in the art knows how to implement a cottonizing treatment step i2).
Individualizing is a treatment in which all or some of the fibers of a set of fibers are separated from one another. Individualizing can, for example, be carried out by combing or by a chemical treatment.
This treatment step i2) may take place before, after or before and after optional cutting step i1).
For example, the bast fibers may undergo, optionally, individualizing treatment step i2), cutting step i1) to obtain bast fibers having a length within the abovementioned ranges, then optionally cottonizing treatment step i2), in particular cutting step i1) to obtain bast fibers having a length within the abovementioned ranges, then cottonizing treatment step i2).
The process may also comprise, between production step i) and introduction step ii), a step ii1) of compacting the web to obtain a compacted web, this compacted web then undergoing introduction step ii).
This compacting step ii1) can make it possible to reduce the thickness of the web in order to control the density of the nonwoven substrate.
According to another very particular embodiment, the process can comprise the following steps:
i) producing a web by a drylaid process from a mixture of natural fibers comprising between 85% and 95% of cottonized flax fibers by weight of solids of said mixture of fibers and between 5% and 15% of lyocell fibers by weight of solids of said mixture of fibers,
ii) introducing a binder chosen from starch, polyvinyl alcohol, ethylene-vinyl acetate or a mixture thereof into the web by spraying an aqueous dispersion of binder,
iii) drying the web resulting from step ii) to obtain a nonwoven substrate which can have a density of between 10 mg/cm³and 40 mg/cm³and in which the mixture of fibers can represent between 85% and 98% by weight of solids of said nonwoven substrate and binder can represent between 2% and 15% by weight of solids of said nonwoven substrate.
Optionally, the nonwoven substrate obtained at step iii) may be calendered.
After step iii) and before step a), the nonwoven substrate may be packed as bobbin, as roll by a spooling process or in paperboard by a festooning process.

EXAMPLES

Example 1: Manufacture of the Nonwoven Substrate

In the Examples, the air permeability is determined using “FX3300 Lab Air IV” Air permeability tester. During the measurements, the tested web is placed under the measurement head and we measured the air flow passing through the web at pressure drop of 200 Pa over the area of 20 cm². The permeability is measured in [cm³/cm²/sec]. For each sample, three measurements were made and the indicated air permeability is the average value.

Example 1.1: Nonwoven Substrate Prepared by a Drylaid Process and Comprising 95% by Weight of Solids of Said Nonwoven Substrate of a Mixture of Cottonized Flax Fibers and of Lyocell Fibers (90% Cottonized Flax/10% Lyocell by Weight of Solids of the Mixture of Fibers) and 5% by Weight of Solids of Said Nonwoven Substrate of Starch

The cottonized flax fibers (VERVAEKE FIBRE NV, 22 mm in length) and the lyocell fibers (1.7 dtex/38 mm in length from Lenzig) were mixed, opened and parallelized with a card before being deposited on a forming fabric. A solution comprising 5% solids content of starch (Perfectafilm X115 manufactured by Avebe) is sprayed onto both sides of the web. The sprayed web is then dried by hot air oven at a temperature of between 100° C. and 120° C. The content of binder in the web is 5%.
The nonwoven substrate obtained has a density of 11 mg/cm³, a thickness of 4190 μm, a grammage of 47 g/m²and an air permeability of 650 cm³·cm⁻²·sec⁻¹.
All the examples have the same fiber size, with an average length before manufacture of 22 mm for the cottonized flax fibers and of 38 mm for the lyocell fibers.

Example 1.2: Nonwoven Substrate Prepared by a Drylaid Process and Comprising 95% by Weight of Solids of Said Nonwoven Substrate of a Mixture of Cottonized Flax Fibers and of Lyocell Fibers (90% Cottonized Flax/10% Lyocell by Weight of Solids of the Mixture of Fibers) and 5% by Weight of Solids of Said Nonwoven Substrate of Starch

The nonwoven substrate is obtained by the process described in example 1.1. After drying, the web was compacted at a pressure of 1 bar. The content of binder in the web is 5%.
The nonwoven substrate obtained has a density of 22 mg/cm³, a thickness of 1900 μm, a grammage of 42 g/m²and an air permeability of 640 cm³·cm⁻²·sec⁻¹.

Example 1.3: Nonwoven Substrate Prepared by a Drylaid Process and Comprising 88% by Weight of Solids of Said Nonwoven Substrate of a Mixture of Cottonized Flax Fibers and of Lyocell Fibers (90% Cottonized Flax/10% Lyocell by Weight of Solids of the Mixture of Fibers) and 12% by Weight of Solids of Said Nonwoven Substrate of Starch

The nonwoven substrate is obtained by the process described in example 1.1. The content of binder in the web is 12%.
The nonwoven substrate obtained has a density of 14 mg/cm³, a thickness of 2040 μm, a grammage of 29 g/m²and an air permeability of 890 cm³·cm⁻²·sec⁻¹.

Example 1.4: Nonwoven Substrate Prepared by a Drylaid Process and Comprising 95% by Weight of Solids of Said Nonwoven Substrate of a Mixture of Cottonized Flax Fibers and of Lyocell Fibers (90% Cottonized Flax/10% Lyocell by Weight of Solids of the Mixture of Fibers) and 5% by Weight of Solids of Said Nonwoven Substrate of Polyvinyl Alcohol

The nonwoven substrate is obtained by the process described in example 1.1. A solution comprising 5% solids content of polyvinyl alcohol (Elvanol 71-30 manufactured by Kuraray) is sprayed onto both sides of the web. The content of binder in the web is 5%.
The nonwoven substrate obtained has a density of 17 mg/cm³, a thickness of 2500 μm, a grammage of 43 g/m²and an air permeability of 800 cm³·cm⁻²·sec⁻¹.

Example 1.5: Nonwoven Substrate Prepared by a Drylaid Process and Comprising 85% by Weight of Solids of Said Nonwoven Substrate of Lyocell Fibers and 15% by Weight of Solids of Said Nonwoven Substrate of Starch

The nonwoven substrate is obtained by the process described in example 1.1. The binder level in the web is 15%.
The non-woven substrate has a density of 13 mg/cm3, a thickness of 2690 μm, a basis weight of 36 g/m²and an air permeability of 660 cm³·cm⁻²·sec⁻¹.

Example 1.6: Nonwoven Substrate Prepared by a Drylaid Process and Comprising 91% by Weight of Solids of Said Nonwoven Substrate of Cottonized Flax Fibers and Lyocell Fibers Mixture (90% Cottonized Flax/10% Lyocell by Weight of the Fiber Mixture) and 9% by Weight of Solids of Said Nonwoven Substrate of Ethylene-Vinyl Acetate

The nonwoven substrate is obtained by the process described in example 1.1. A solution comprising 3% of ethylene-vinyl acetate solids (®Vinamul Elite 15 manufactured by Celanese) was sprayed on both sides of the web. The content of binder in the web is 9%.
The non-woven substrate has a density of 22 mg/cm3, a thickness of 1600 μm, a basis weight of 38 g/m²and an air permeability of 712 cm³·cm⁻²·sec⁻¹.

Example 1.7: Nonwoven Substrate Prepared by a Drylaid Process and Comprising 92% by Weight of Solids of Said Nonwoven Substrate of Cottonized Flax Fibers and Lyocell Fibers Mixture (90% Cottonized Flax/10% Lyocell by Weight of the Fiber Mixture) and 8% by Weight of Solids of Said Nonwoven Substrate of Starch

The nonwoven substrate is obtained by the process described in example 1.1. After the drying, the web was calendared with a pressure of 7 bar. The binder level in the web is 8%.
The non-woven web has a density of 44 mg/cm3, a thickness of 900 μm and a basis weight of 40 g/m².

Example 2: Manufacture and Characterization of Filters for a Smoking Article

Filters for a smoking article were manufactured with the substrates of examples 1.1 to 1.7 by a standard method for manufacturing filters without passage through a crimping machine. A nonporous plug wrap paper was used to wrap the rods of nonwoven filtering material.
The filters of the invention were compared with the paper filter and with the commercial cellulose acetate filter. The paper filter was made using a standard method for manufacturing filters by crimping the substrate CF 36 of 36 g/m²and 100 μm thickness. The filters obtained for each term were cut into 21-mm sticks.
The characteristics of the filters are given in table 1 below.

Example 3: Manufacture and Characterization of Cigarettes

Cigarettes were prepared using the filters described in example 2. To form the cigarettes, the rods of tobacco were assembled with the filters using tipping paper. A commercial “American blend” tobacco was used to form the rods of tobacco. The cigarettes were prepared with a pressure difference similar to that of the commercial cigarette. The ventilation of the cigarettes was blocked.
The cigarettes prepared were smoked on a Borgwaldt RM20 smoking machine in accordance with the standard ISO 3308:2000. The pressure drop (PD in table 2) was measured in accordance with the standard ISO 6565:2002. The nicotine content in the smoke was measured in accordance with the standard ISO 10315:2000. The smoking results are given in table 2 below.
Table 2 demonstrates that, with an equivalent pressure drop, the cigarettes with filters according to the invention and the cigarettes comprising a commercial cellulose acetate filter have a nicotine content in the smoke which is of the same order of magnitude, whereas the cigarettes comprising a filter made from crimped paper have a much lower nicotine content in the smoke.
This example 3 thus demonstrates that the user experience provided by the cigarettes comprising the filters comprising the substrate according to the invention is as satisfactory as that provided by cigarettes comprising a commercial cellulose acetate filter.

TABLE 1

	Filter	Filter	Filter	Filter	Filter	Filter	Filter
Commercial	comprising	comprising	comprising	comprising	comprising	comprising	comprising	Filter
cellulose	the substrate	the substrate	the substrate	the substrate	the substrate	the substrate	the substrate	made from
acetate	of	of	of	of	of	of	of	crimped CF36
filter	example 1-1	example 1-2	example 1-3	example 1-4	example 1-5	example 1-6	example 1-7	paper

Length of the	21
filters [mm]
Diameter of the	7.8
filters [mm]

Weight of the	139 ± 5	115 ± 1	134 ± 1	155 ± 1	147 ± 1	149 ± 1	154 ± 1	157 ± 5	221 ± 1
filters [mg]
Density of the	138	117	137	159	150	150	150	151	226
filters [mg/cm³]

TABLE 2

	Filter	Filter	Filter	Filter	Filter	Filter	Filter
Commercial	comprising	comprising	comprising	comprising	comprising	comprising	comprising	Filter
cellulose	the substrate	the substrate	the substrate	the substrate	the substrate	the substrate	the substrate	made from
acetate	of	of	of	of	of	of	of	crimped CF36
filter	example 1-1	example 1-2	example 1-3	example 1-4	example 1-5	example 1-6	example 1-7	paper

Number of	30
cigarettes
smoked

PD of the	104 ± 1	90 ± 1	93 ± 1	91 ± 1	100 ± 1	107 ± 1	103 ± 1	96 ± 5	100 ± 1
cigarettes
[mmWC]
Nicotine	0.85 ± 0.04	0.85 ± 0.04	0.71 ± 0.05	0.78 ± 0.05	0.78 ± 0.05	0.71 ± 0.04	0.70 ± 0.03	0.71 ± 0.07	0.5 ± 0.19
[mg/cigarette]

Claims

1. Filter comprising a nonwoven substrate comprising natural fibers and a binder, in which the natural fibers represent between 70% and 99% by weight of solids of said nonwoven substrate, the binder represents between 1% and 30% by weight of solids of said nonwoven substrate,

characterized in that the nonwoven substrate has a density of between 7 mg/cm3 and 60 mg/cm3.

2. Filter according to claim 1, in which the nonwoven substrate has a thickness of between 700 μm and 6000 μm.

3. Filter according to claim 1, in which the length of the natural fibers is greater than 10 mm and less than or equal to 150 mm.

4. Filter according to claim 1, in which the natural fibers are chosen from wood fibers, leaf fibers, fruit fibers, seed fibers, bast fibers, stalk fibers, reed fibers and mixtures thereof.

5. Filter according to claim 4, in which the wood fibers are chosen from lyocell fibers, viscose fibers, and mixtures thereof.

6. Filter according to claim 4, in which the bast fibers are chosen from hemp fiber, Indian hemp fiber, jute fiber, kenaf fiber, kudzu fiber, flax fiber, okra fiber, nettle fiber, ramie fiber, and mixtures thereof.

7. Filter according to claim 1, in which the binder is a synthetic polymer or copolymer.

8. Filter according to claim 1, in which the binder is chosen from a polysaccharide, preferably starch, a cellulose derivative, and mixtures thereof.

9. Filter according to claim 1, in which the binder is a polyvinyl alcohol, a polyvinyl acetate, or an ethylene-vinyl acetate.

10. Filter as defined in claim 1 for smoking article or vaping article.

11. Smoking article comprising a filter as defined in claim 1.

12. Vaping article comprising a filter as defined in claim 1.

13. Process for producing a filter for a smoking or vaping article comprising a nonwoven substrate, said process comprising the following steps:

a) forming a rod of nonwoven substrate from a nonwoven substrate,

b) wrapping the rod of nonwoven substrate with a sheet of plug wrap paper,

c) depositing an adhesive line, joining the sheet of plug wrap paper to obtain a rod of filtering material,

d) cutting the rod of filtering material to produce the filter,

wherein the nonwoven substrate is as defined in claim 1 or is obtained by a process comprising the following steps:

i) producing a web from natural fibers by a drylaid process,

ii) introducing the binder into the web, and

iii) drying the web resulting from step ii) to obtain the nonwoven substrate.

14. Process according to claim 13 in which, after step iii) and before step a), the nonwoven substrate is packed as bobbin, as roll by the spooling process or in paperboard by the festooning process.