RU2781358C2 - Solid filter for aerosol generating product - Google Patents

Abstract

FIELD: tobacco industry.

SUBSTANCE: invention relates to an aerosol generating product. Aerosol generating product (10) contains aerosol forming substrate (20) and filter (30) located further along the stream relatively to substrate. The aerosol generating product has an average radial hardness of 95.5% or more, when measured by the circumference of the filter. The filter contains filtering material and has drag resistance of less than 3.3 mm WG.

EFFECT: increased hardness of a filter is provided, while saving drag resistance similar to less solid filters.

13 cl, 1 dwg, 2 tbl

Description

The present invention relates to aerosol generating articles and filters for aerosol generating articles having increased hardness.

Aerosol-generating articles include articles that can be burned to form an aerosol or heated without being burned to form an aerosol, as well as articles that can aerosolize a substrate or composition in any other suitable manner, such as through a chemical reaction or entrainment of particles into the air. Regardless of the aerosol generating mechanism, aerosol generating articles may include a filter located downstream of the aerosol generating substrate to filter one or more aerosol constituents.

For example, combustible aerosol-generating articles such as cigarettes typically contain cut tobacco, usually in the form of cut filler, surrounded by a paper wrapper to form a tobacco rod. To use the cigarette, the smoker ignites one end of the cigarette and burns the tobacco rod. In this case, the smoker receives inhaled smoke by puffing on the opposite end or mouth end of the cigarette, which usually encloses the filter. The filter is positioned to capture some constituents of the inhaled smoke before the inhaled smoke is delivered to the smoker.

Filters in aerosol-generating articles typically comprise a filter material surrounded by ficellus. Fitella contributes to the rigidity of the filter. For the production of stronger and harder filters, ficells with higher rigidity can be used, for example, ficells made from paper with a higher density. Ficells with increased stiffness are able to assist, for example, in extinguishing a combustible aerosol-generating article by pressure due to their increased longitudinal rigidity, and they are able to give a higher quality product feel when pressed by the consumer due to their increased radial hardness.

However, wrapping the rigid ficelle around the filter media can be difficult. For example, in order for a stiffer ficell to be wrapped around the filter material, equipment may need to be changed in filter production lines.

Another option for increasing the hardness of the filter may be to increase the weight of the tow of the filter material used. In other words, the density of the filter material can be increased. However, increasing the density of the filter material can increase filtration efficiency and prevent the required amount of aerosol constituents from passing through the filter, resulting in an unexpected or undesirable taste or sensation. It is also possible to undesirably increase draw resistance in an aerosol generating article using a higher density filter material compared to an article using a higher than standard density filter material.

It is desirable to provide such a filter for use in an aerosol generating article that has an increased hardness. It is also desirable to provide such a filter for use in an aerosol generating article that has a similar draw resistance to less rigid filters.

In various aspects of the present invention, an aerosol-generating article is provided, comprising an aerosol-generating substrate and a filter located downstream of the substrate. The aerosol generating article has an average radial hardness of 95% or more when measured along the circumference of the filter. Preferably, the filter has a draw resistance of 90 mm w.c. Art. or less, for example 70 mm of water. Art. or less or 50 mm of water. Art. or less.

Preferably, the aerosol generating article has an average radial hardness of 95.5% or more as measured around the circumference of the filter, and the filter material has a draw resistance of 70 mm of water. Art. or less with a filter length of 21 mm.

The filter may contain filaments of filter material. It has been found that increasing the linear density of the filter material filaments allows the use of a higher density filter material while maintaining the desired filtration efficiency and draw resistance. The increased density of the filter material makes it possible to increase the hardness of the filter.

The filter may contain a plasticizer which is capable of bonding the fibers of the filter material to each other. It has been found that by using threads of the correct linear density and filter material of the correct density, it is possible to use increased amounts of plasticizer. Increased plasticizer concentrations allow higher filter hardness to be achieved, but they can increase draw resistance and reduce filtration efficiency. Accordingly, as described herein, it is possible to achieve a suitable combination of filament density, filter media density, and plasticizer concentration to increase filter hardness while providing suitable filtration efficiency and draw resistance.

The hardness of the filter can be further increased by using a stiffer filament, a thicker filament, a filament made from a harder material, or strength coatings applied to the filament.

Accordingly, filters having an average radial hardness greater than 95% can be made by proper selection of a suitable filter media having filaments of a suitable linear density, a suitable overall density of the filter material, a suitable amount of plasticizer and a suitable weight, thickness and stiffness ficell. These filters are also capable of providing the required filtration performance, such as 70 mm w.c. draw resistance. Art. or less.

The inclusion of hardened filters in the aerosol generating articles allows the aerosol generating articles to be perceived as having a higher quality. The increased hardness of the filter may also be advantageous, for example, when extinguishing by pressing down a combustible aerosol-generating article, such as a cigarette, containing said filter. For example, the hardened filter is able to keep the user's fingers away from the burning end of the cigarette when pressing down on the cigarette because the filter may be less likely to warp during the cigarette extinguishing process.

The above-described advantages, as well as other advantages, will become readily apparent to those skilled in the art upon reading and understanding the present disclosure.

The aerosol generating articles of the present invention can have previously unattainable average radial hardness of 95% or more as measured around the circumference of the filter while maintaining desired filter properties such as draw resistance. For example, aerosol generating articles may have an average radial hardness of 96% or more, 97% or more, or 98% or more when measured around the filter circumference. Preferably, the aerosol generating articles have an average radial hardness of from about 95% to about 99% as measured around the circumference of the filter. In the context of this document, the term "radial hardness" refers to the resistance to compression in the direction transverse to the longitudinal axis. The radial hardness of the aerosol generating article around the circumference of the filter can be determined by applying a load to the article at the location of the filter transverse to the longitudinal axis of the article and measuring the mean (averaged) diameters of the compressed articles. Radial hardness is determined as follows:

where D _S is the original diameter (uncompressed) and D _d is the diameter of the compressed product after applying a given load for a given period of time. The harder the material, the closer its hardness is to 100%.

In order to determine the hardness of a part (such as a filter) of an aerosol generating article, the aerosol generating articles must be aligned parallel in plan and the same parts to be tested of all aerosol generating articles must be subjected to a given load for a given period of time. This test is carried out using a known densimeter device DD60A (manufactured and marketed by Heinr. Borgwaldt Gmbh, Germany), which is equipped with a measuring head for aerosol generating products such as cigarettes and a holder for aerosol generating products.

The load is applied by two cylindrical load application bars that cover the diameters of all aerosol generating articles simultaneously. According to the standard test method for this tool, the test should be carried out in such a way that there are twenty points of contact between the aerosol generating articles and the cylindrical load application bars. In some cases, the filters to be tested may be long enough that only ten smoking articles are needed to obtain twenty points of contact, and each smoking article must be in contact with both rods to apply the load (because it is long enough to pass between the rods). In other cases, if the filters are too short to accomplish the above, then twenty smoking articles should be used to obtain twenty points of contact, with each smoking article only contacting one of the load bars, as further described below.

Two additional fixed cylindrical rods are placed below the smoking articles to support the aerosol generating articles and counteract the load applied by each of the cylindrical rods to apply the load.

The standard operating procedure for such a device is to apply a total load of 2 kg for 20 seconds. After 20 seconds (and with continued application of load to smoking articles), the amount of indentation of the cylindrical rods to apply the load is determined and then used to calculate the hardness according to the above equation. The temperature is maintained around 22 degrees Celsius ± 2 degrees. The above test is referred to as Test DD60A. The standard method for measuring the hardness of a filter is carried out in a state where the aerosol generating article is not consumed. Additional information regarding the measurement of average radial hardness can be found, for example, in published patent application US No. 2016/0128378.

In some preferred examples, filters according to the present invention have an average radial hardness of 90% or more, such as 92% or more or 94% or more. For example, filters according to the present invention may have an average radial hardness of 95% or more, such as 95.5% or more. More preferably, the filters have an average radial hardness of 96% or more, such as 97% or more. For example, filters according to the present invention may have an average radial hardness in the range of from about 95% to about 99%, such as from about 95% to about 98%.

In the context of this document, the term "diameter" is used to describe the maximum size in the transverse direction (transverse to the longitudinal axis) of the filter or aerosol generating article that contains the filter. The longitudinal axis of the filter or aerosol generating article extends in the length direction of the filter or aerosol generating article. For the purposes of the present invention, the term "radius" refers to the transverse distance from the longitudinal axis to the edge of the filter or aerosol generating article. Typically, the filter and the smoking article are cylindrical in shape. However, the filter and/or smoking article need not be cylindrical.

Aerosol generating articles containing the filters of the present invention may have any suitable draw resistance (RTD). The term "resistance to draw" refers to the difference in static pressure between the two ends of the sample during the passage of air flow through it under steady-state conditions, according to which the volume flow is 17.5 milliliters per second at the outlet end. The RTD of a sample can be measured using the method described in ISO 6565:2002. Preferably, aerosol generating articles containing filters according to the present invention have an RTD similar to traditional cigarettes.

In some preferred examples, aerosol generating articles containing the filters of the present invention have an RTD from about 40 mm of water column (mm of water column) to about 200 mm of water. Art., preferably from about 50 mm of water. Art. up to approximately 140 mm w.c. Art., and more preferably from about 50 mm of water. Art. up to about 100 mm w.c. Art. Preferably, the filters have an RTD of 90 mmH2O. Art. or less, for example 70 mm of water. Art. or less. More preferably, the filters have an RTD of 65 mmH2O. Art. or less, for example 60 mm of water. Art. or less.

The RTD of the filter at the rod length used in the aerosol generating article can be from about 40 mm of water column (mm of water column) to about 200 mm of water. Art., preferably from about 50 mm of water. Art. up to approximately 140 mm w.c. Art., and more preferably from about 50 mm of water. Art. up to about 100 mm w.c. Art. The RTD of the filter at the length used in the aerosol generating article may be 90 mm of water. Art. or less, for example 70 mm of water. Art. or less. More preferably, the filters have an RTD of 65 mmH2O. Art. or less, for example 60 mm of water. Art. or less.

The RTD of the filter material according to the present invention, with a rod length of 126 mm, is preferably from about 40 mm of water column (mm of water column) to about 200 mm of water. Art., preferably from about 50 mm of water. Art. up to approximately 140 mm w.c. Art., more preferably from about 50 mm of water. Art. up to about 100 mm w.c. Art. Preferably, the filters have an RTD of 90 mmH2O. Art. or less, for example 70 mm of water. Art. or less. More preferably, the filters have an RTD of 65 mmH2O. Art. or less, for example 60 mm of water. Art. or less. Preferably, the RTD of the filter with a 126 mm rod length is 90 mmH2O. Art. or less, for example 70 mm of water. Art. or less. More preferably, the RTD of filters with a 126 mm rod length is 65 mm w.c. Art. or less, for example 60 mm of water. Art. or less.

In some preferred embodiments, the RTD of the filter material of the present invention, with a rod length of from about 15 mm to about 40 mm, such as about 21 mm, is from about 40 mm of water column (mm of water column) to about 200 mm of water. Art., preferably from about 50 mm of water. Art. up to approximately 140 mm w.c. Art., more preferably from about 50 mm of water. Art. up to about 100 mm w.c. Art. Preferably, the filters have an RTD of 90 mmH2O. Art. or less, for example 70 mm of water. Art. or less. More preferably, the filters have an RTD of 65 mmH2O. Art. or less, for example 60 mm of water. Art. or less or 50 mm of water. Art. or less. Preferably, the RTD of a filter with a shaft length of from about 15 mm to about 40 mm, for example about 21 mm, is 90 mm of water. Art. or less, for example 70 mm of water. Art. or less, 65 mm w.c. Art. or less or 60 mm of water. Art. or less.

Filters having shorter lengths may have a lower RTD than filters with longer lengths, particularly if the filters are made from the same material in the same way. In some preferred embodiments, the RTD of filters having a shaft length of from about 15 mm to about 40 mm, such as about 21 mm, is from about 30 mm of water. Art. up to approximately 90 mm w.c. Art., from approximately 40 mm of water. Art. up to approximately 70 mm w.c. Art., from approximately 40 mm of water. Art. up to approximately 65 mm w.c. Art. or from about 40 mm w.c. Art. up to approximately 60 mm w.c. Art.

Preferably, the filters have an RTD of 90 mmH2O. Art. or less, for example 70 mm of water. Art. or less, 65 mm w.c. Art. or less, or 60 mm of water. Art. or less with a filter length of 21 mm. In other words, the RTD of the filters is approximately 4.3 mmH2O. Art. or less, 3.3 mm of water. Art. or less, 3.1 mm of water. Art. or less or 2.9 mm of water. Art. or less per mm of filter length.

Filters and related aerosol generating articles may have any suitable relationship between RTD and average radial hardness. For example, the quotient of the RTD value of the filter divided by the value of the average radial hardness of the aerosol generating article is 0.75 mm of water. Art./% or less. Preferably, the RTD value of the filter divided by the mean radial hardness value of the aerosol generating article is 0.7 or less. More preferably, the RTD value of the filter divided by the mean radial hardness value of the aerosol generating article is 0.65 or less. Preferably, the RTD value of the filter divided by the mean radial hardness value of the aerosol generating article is 0.3 or more, such as 0.35 or more or 0.4 or more. For example, the RTD value of the filter divided by the average radial hardness of the aerosol generating article may be from about 0.3 to about 0.75, from about 0.35 to about 0.7, or from about 0.4 to about 0.65. .Filters and related aerosol-generating articles may have any suitable value of (100-hardness) x RTD, where hardness is an average radial hardness value (%) and RTD is an RTD value in mm of water. Art. For example, filters and associated aerosol generating articles may have a (100-hardness) x RTD in the range of about 40 to about 2000. Preferably, filters and associated aerosol-generating articles have a (100-hardness) x RTD in the range of about 40 to approximately 1000; more preferably from about 40 to about 500.

Filters and related aerosol generating articles may have any suitable value of [(100-hardness) x RTD]/mm filter], where (100-hardness) x RTD is defined above and filter mm is the length of the filter. Preferably, the filters have a value of [(100-hardness) x RTD]/mm filter] of 20 or less; more preferably 15 or less; and even more preferably 10 or less. For example, filters may have a value of [(100-hardness) x RTD]/mm filter] of 9 or less, 8 or less, 7 or less, or 6 or less. For example, filters may have a value for [(100-hardness)xRTD]/mm filter from about 2 to about 20; preferably from about 3 to about 15, and more preferably from about 5 to about 13. In some preferred embodiments, the filters have a value of [(100-hardness) x RTD]/mm filter] from about 4 to about 8, from about 4 to about 7, from about 5 to about 5, or from about 5 to about 7.

In the filters of the present invention, suitable hardness and draw resistance can be achieved by including suitable amounts of filter material with suitable thread size and plasticizer concentration, as well as by selecting a ficell having the proper characteristics.

According to the present invention, any suitable filter material can be used. Examples of suitable filter media include cellulose esters such as cellulose acetate, polylactic acid (PLA), cellulosic material, or any degradable filter media, or a combination or mixture of any two or more filter media. In preferred embodiments, the filter material includes a polymeric filter material such as polylactic acid, cellulose esters, and mixtures thereof. Preferably, the filter material comprises a cellulose ester. Examples of cellulose esters that can be used to form a filter material include cellulose acetates, cellulose propionates and cellulose butyrates in various degrees of substitution, as well as their mixed esters. Examples of such mixed esters include cellulose acetate propionate, cellulose acetate butyrate, and cellulose acetate propionate butyrate. Preferably, the filter material contains cellulose acetate.

Preferably, the filter material contains less than 10% by weight of particles having a size in the range of 0.1 mm to 1.7 mm. For example, the filter material may contain less than 5% by weight or less than 1% by weight, with particles ranging in size from 0.1 mm to 1.7 mm. Preferably the filter material does not contain (contains 0%) particles having a size in the range of 0.1 mm to 1.7 mm. More preferably, the filter material does not contain cellulose acetate particles having a size in the range of 0.1 mm to 1.7 mm, or contains 10% or less, 5% or less, or 1% or less cellulose acetate particles having a size in the range from 0.1 mm to 1.7 mm. The filter may contain cellulose acetate tow and be free of cellulose acetate particles having a size in the range of 0.1 mm to 1.7 mm.

The plasticizer-containing filter material may be of any suitable tow weight or density. Preferably, the filter material has a weight of from about 5 mg/mm to about 7 mg/mm. More preferably, the filter material has a weight of from about 5.5 mg/mm to about 6.5 mg/mm. Preferably, the filter has a density of from about 0.11 g/cm ³ to about 0.2 g/cm ³ . Preferably, the filter has a density of from about 0.12 g/cm ³ to about 0.19 g/cm ³ , for example from about 0.12 g/cm ³ to about 0.15 g/cm ³ . Filters that have higher weight and density values are generally harder than those that have lower weight and density values. However, increasing the weight or density of the filter media may also tend to increase the RTD to undesirable levels, or may result in too much aerosol being filtered and thus preventing sufficient aerosol from being delivered to the user.

To reduce the effect of increased filter weight or density on RTD and filtration, filters may contain filaments having a denier of 4 denier per filament or more. The linear density of the filaments used in filters can be measured by determining the weight of the filament in grams per 9000 meters. Preferably, the filters of the present invention comprise filaments having a linear density of 5 denier per thread or more, 6 denier per thread or more, or 7 denier per thread or more. For example, filters according to the present invention may contain filaments having a linear density of approximately 8 denier per filament. Preferably, the yarns having the above measured densities are cellulose acetate yarns.

Filters according to the present invention may have any suitable amount of plasticizer. In the context of this document, the term "plasticizer" means a solvent which, when applied to polymeric fibers, bonds the fibers to each other through its action as a solvent. Examples of plasticizers include triacetin (also known as glycerol triacetate), diethylene glycol diacetate, triethylene glycol diacetate, tripropion, acetyl triethyl citrate, triethyl citrate, and mixtures of one or more of these. Preferably, the plasticizer contains triacetin. One or more plasticizers may be mixed with, for example, polyethylene glycol and brought into contact with the polymer fibers to bind the fibers together by the action of the solvent. The fibers may be brought into contact with the binder in any suitable manner. Preferably, the composition containing the binder is sprayed onto the polymer fibers.

Preferably, the filters contain 7% or more plasticizer based on the weight of the filter material. For example, filters may contain 7 grams or more of plasticizer per 100 grams of CA if the filter is a CA filter. More preferably, the filter contains 8% or more plasticizer, or 9% or more plasticizer. For example, the filter may contain approximately 10% plasticizer. More preferably, the filter contains from about 7.5% by weight to about 11.5% by weight of the plasticizer. Preferably, the filters contain from about 7.5% to about 10% plasticizer. For example, the filter may contain from about 8% to about 11% plasticizer, or from about 8% to about 10% plasticizer.

The authors of the present invention have found that a certain amount of plasticizer in the filters according to the present invention makes it possible to obtain a filter having the desired hardness, RTD and filtration efficiency. If the amount of plasticizer exceeds about 12%, especially if the amount of plasticizer exceeds about 13%, then the quality of the filter tends to deteriorate. For example, if the CA filter contains more than about 12% triacetin, then this results in relatively large voids in the filter, which can significantly reduce filtration efficiency and render the filter unacceptable.

By choosing the proper combination of filter weight or density, filament linear density and plasticizer, suitable filtration, hardness and draw resistance can be achieved.

The filter may include a ficell located around the filter material. Fitella can contribute to filter hardness. Ficella may be coated with any suitable hardening coating composition. Preferably, the ficell contains a coating, which preferably increases the radial hardness and longitudinal hardness of the filter containing the coated ficell.

Any suitable hardening coating composition may be applied to the filter ficell of the present invention. Preferably, the hardness-enhancing coating composition does not result in a coating that adversely affects taste perception during smoking of a smoking article comprising a coated filter. In some preferred embodiments, the hardening coating composition contains one or more components such as binders or other additives used in the manufacture of cigarettes. For example, the coating composition may contain a suitable binder used in cigarette paper, tip paper or ficells.

Examples of suitable materials that may be included in the hardening coating composition are starch, polyacrylamide derivatives, styrene-butadiene, styrene-acrylic compounds, dextrin, oxidized starch, ethylcellulose, cellulose acetate, carboxymethylcellulose, hydroxyethylcellulose or other suitable cellulose derivatives; pectins; guar gum; carob bean flour; agar; sodium alginate or other suitable alginates; etc. In some preferred embodiments, the hardening coating comprises polyvinyl alcohol.

Any suitable ficell may be coated with a hardening coating. Preferably, the ficell contains, consists essentially of, or consists of paper ficell.

Fitzella can have any suitable density. Preferably, the ficell has a density of from about 20 grams per square meter to about 180 grams per square meter. More preferably, ficella has a density of from about 50 grams per square meter to about 150 grams per square meter; and even more preferably from about 50 grams per square meter to about 100 grams per square meter.

The fitella may be of any suitable thickness. Suitable ficell paper may have a thickness of from about 25 micrometers to about 200 micrometers; preferably from about 50 micrometers to about 200 micrometers. In some preferred embodiments, the ficell has a thickness of from about 100 micrometers to about 150 micrometers.

Ficella with higher density and greater thickness is usually harder than Ficella with lower density and thinner thickness.

Fitella may have any suitable stiffness. Ficell stiffness can be determined using ISO 2493-1:2010: Paper and paperboard - Determination of bending resistance - Part 1: Constant deflection rate, ISO 2493-2:2011: Paper and paperboard - Determination of bending resistance - Part 2: Taber test , or both from ISO 2493-1:2010 and ISO 2493-2:2011. Preferably, the stiffness of the ficell in the machine direction with a bending effect of 15° over a length of 10 mm (MD - 15° 10 mm) is 100 mN•mm or more. For example, the ficell may have a stiffness (MD - 15º 10 mm) from about 100 mN•mm to about 500 mN•mm. Preferably, the ficell has a stiffness (MD - 15º 10 mm) from about 120 mN•mm to about 450 mN•mm.

Preferably, the stiffness of the ficell in the transverse direction at a bending effect of 15° over a length of 10 mm (CD - 15° 10 mm) is 40 mN•mm or more. For example, the ficell may have a stiffness (CD - 15° 10 mm) from about 40 mN•mm to about 250 mN•mm. Preferably, the ficell has a hardness (CD - 15º 10 mm) of about 50 mN•mm to about 200 mN•mm.

The fitella may have any suitable porosity, or even be non-porous. For example, the ficell may have a relatively high porosity, such as greater than about 1000 Coresta units or greater than about 5000 Coresta units. In addition or alternatively, the ficell may have a porosity of less than about 10,000 Coresta units.

The filter according to the present invention may contain additional material such as activated carbon; flavorants, which may be present in the form of mixtures, flavor threads, granules, capsules, or the like; or any other suitable material. The additional material may be included in the filter media, or it may be located in cavities between the filter media plugs, such as in a plug-gap-plug configuration. In such a configuration, the ficell described herein may be particularly advantageous due to the increase in structural hardness within said cavities.

The filters of the present invention may be of any suitable size. Typically, filters are cylindrical in shape. Preferably, the filter has a diameter in the range of about 5 mm to about 10 mm. More preferably, the diameter is from about 7.0 mm to about 8.0 mm, more preferably from about 7.7 mm to 7.8 mm. Preferably, the diameter of the filter is the same or substantially the same as the diameter of the aerosol generating article in which it is included.

The filter length (which is the overall length of the filter, including the filter material plug, measured in a direction substantially parallel to the longitudinal axis of the aerosol generating article) may be any suitable value. However, it may be convenient for the length of the filter to be substantially the same as in conventional aerosol generating articles. The term "length" refers to the total length of the filter, including the plug of the filter material. In other words, if the filter contains one or more filter segments in addition to the filter material plug, then the length is the total length of all filter segments and the filter material plug. If the filter contains only the filter material plug, then the length is the length of the filter material plug only.

Longer filters generally have a larger RTD than shorter filters.

Preferably, the filter has a length of from about 15 mm to about 40 mm. Even more preferably, the filter has a length of from about 18 mm to about 27 mm. In one embodiment, the filter is approximately 27 mm long. In yet another embodiment, the filter is approximately 21 mm long.

The filters according to the present invention are preferably manufactured using conventional filter manufacturing equipment. For example, the filter material may be made from strips of tow using conventional equipment. The plasticizer can be incorporated using conventional equipment and the ficelle can be positioned around the filter using conventional equipment.

The filters of the present invention may be incorporated into any suitable aerosol generating article in any suitable manner. Preferably, the filter is included in the aerosol generating article downstream of the aerosol generating substrate material. The term "downstream" refers to the relative positions of the elements of the aerosol generating article, as described with respect to the direction of the inhaled aerosol as it is drawn from the aerosol generating substrate into the wearer's mouth.

The term "aerosol-generating article" includes cigarettes, cigars, cigarillos, and other articles in which an aerosol-generating substrate, such as tobacco, is ignited and burned to produce smoke. The term "aerosol-generating article" also includes articles in which the aerosol-generating substrate is not combusted, such as, but not limited to, aerosol-generating articles in which the aerosol-generating substrate is directly or indirectly heated, or aerosol-generating articles in which an air flow or a chemical reaction, with or without a heat source, to deliver nicotine or other materials from an aerosol-generating substrate.

The filters of the present invention may be particularly desirable for use in non-combustible heated articles in which the aerosol-forming substrate is not combusted. Such products often use relatively short filters having a low RTD. Filters in non-burn heated products are often soft, and they can become even softer during use as aerosol flows through the filter. In some cases, the filters may at least partially collapse or collapse during use, which may adversely affect the consumer's perceived quality of the product. Accordingly, by incorporating the filters of the present invention into non-combustion heated products that use relatively short filters and a low RTD, it is possible to improve the perceived quality of the product due to filter stiffness and lack of shrinkage and collapse. Due to the increased rigidity and improved filter qualities, it is possible to use short filters, which provide a relatively low degree of filtration, in non-burning heated products, which allows taste and other organoleptic qualities similar to traditional smoking products such as cigarettes.

Non-burning heated article filters may be of any suitable length. For example, the filters may have a length of less than about 40 mm, such as from about 10 mm to about 40 mm. Preferably, the filter has a length of less than about 30 mm, such as less than about 20 mm.

Let us now turn to the drawings, which illustrate some aspects of the present invention. It should be understood that other aspects not shown in the drawings are also within the scope and spirit of the present invention. The schematic drawings are not necessarily drawn to scale. The same numbers used in the figures refer to the same components, steps, and the like. However, it should be understood that the use of a number to designate a component in a given figure is not intended to limit a component in another figure designated by the same number. In addition, the use of different numbers to designate components in different figures is not intended to indicate that components with different numbers cannot be the same or similar to components with different numbers.

FIG. 1 shows a schematic perspective view of an embodiment of a partially deployed aerosol generating article 10 having a filter 30 . The aerosol-generating article 10 , in the illustrated embodiment, a cigarette, is shown partially expanded to show the major components of the article only. The aerosol-generating article 10 comprises a rod of aerosol-forming substrate 20 ', such as a tobacco rod, and a filter 30 ' located downstream of the aerosol-forming substrate 20 '. The filter 30 and rod 20 are coaxially aligned with the longitudinal axis of the smoking article 10 , which is indicated by the line AA. The depicted smoking article 10 comprises coated ficell 60 , cigarette paper 40 , and tip paper 50 '. The cigarette paper 40 surrounds at least a portion of the stem 20 '. The rim paper 50 or other suitable wrapper surrounds the ficell 60 and the cigarette paper portion 40 as is well known in the art. Filter 30 contains ficell 60 and filter material 32 .

The above examples of embodiments are not limiting. Those skilled in the art will appreciate other embodiments consistent with the exemplary embodiments described above.

All scientific and technical terms used in this document have the meanings commonly used in the art, unless otherwise indicated. The definitions provided in this document are intended to facilitate understanding of some of the terms commonly used in this document.

As used herein, the singular forms include embodiments containing references in the plural, unless the content clearly implies otherwise.

As used in this application, the union "or" is usually used in the meaning, including "and/or", unless the content clearly implies otherwise. The union "and/or" means one or all of the listed elements or a combination of any two or more of the listed elements.

In the context of this document, the words "have", "having", "include", "including", "comprise", "comprising", or the like, are used in their broad sense and generally mean "including, but without limitation". It should be understood that the expressions "consisting essentially of", "consisting of", etc., are in the category of "comprising", etc.

The words "preferred" and "preferably" refer to embodiments of the present invention that are capable of providing certain advantages under certain conditions. However, other embodiments may also be preferred under the same or different conditions. Furthermore, the disclosure of one or more preferred embodiments is not meant to imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the present invention, including the claims.

EXAMPLES

The following are non-limiting examples illustrating the choice of filter material weight, plasticizer weight percentage and filament linear density, as well as ficell properties that provide increased filter hardness. Nineteen filters were made from cellulose acetate tows (y-shaped fibers) having different linear densities of threads and different amounts of plasticizer (triacetin). The resulting filter materials were wrapped in ficells with different density and thickness. The finished filters had a diameter of 7.71 mm and a length of 126 mm. The materials used in the manufacture of some of the nineteen filters are shown in Table 1 below.

Table 1: Components of tested filters

Sample number one 2 four 5 12 13 fifteen Triacetin % 7 7 7 ten 7 ten ten Linear thread weight (denier) 3 3.4 3.4 3.4 eight eight eight Paper thickness 148 148 100 100 100 100 100 Paper density 61 61 78 78 78 78 78

The average radial hardness of 126 mm long filter rods was determined as described in US Published Application No. 2016/0128378. The RTD of the 126 mm filter rods was measured according to ISO 6565:2002. Ficella stiffness was measured according to ISO 2493-1:2010 and ISO 2493-2:2011. For some filters, the weight of the filter material and plasticizer was determined, as well as the density of the suspended material (based on a diameter of 7.71 mm). The results are presented in Table 2 below:

Table 2 : Filter properties

Sample number one 2 four 5 12 13 fifteen Fiber weight+
plasticizer (mg) 706.2 728.1 Density (g/cm3) 0.119 0.123 paper hardness - MD - 15° 10 mm (mN•mm) 135 135 323 323 323 323 323 paper hardness - CD - 15° 10 mm (mN•mm) 75 75 165 165 165 165 165 Percentage value of radial hardness 92.200 94.650 95.413 95.827 95.963 96.460 97.373 RTD (mm w.c.) 340 330 360 369 206 206 255 (100-hardness)xRTD 2652 1765.5 1651.3 1539.8 831.6 729.2 669.9 [(100-Hardness)xRTD]/mm] 21.0 14.0 13.1 12.2 6.6 5.8 5.3

As shown in Table 1 and Table 2 , increasing the density and thickness of the ficell tends to increase the stiffness of the ficell and the hardness of the filter. An increase in the linear density of the threads tends to increase the radial hardness. Increasing the weight fraction of the plasticizer also tends to increase the radial hardness.

Increasing the linear density of the threads and the weight fraction of the plasticizer tends to increase the weight and density of the filter, which directly correlates with the radial hardness.

It should be noted that the RTD was determined on filter rods having a length of 126 mm, which may be longer than rods that may be used in some aerosol generating products. For illustrative purposes, filter 15 had a 255 mmH2O RTD. Art., i.e. The RTD per mm was approximately 2.02, which is estimated to correspond to an RTD of approximately 42.5 mmH2O. Art. for a filter having a length of 21 mm. Thus, it is estimated that a 21 mm long filter as filter 15 will have an average radial hardness of 97.607% (since the length should not significantly affect the radial hardness), and at the same time, its RTD will be approximately 42.5 mm of water. Art. The quotient of such a filter's RTD value divided by the average radial hardness of an aerosol generating article containing such a filter will be approximately 0.44.

A filter having such a high hardness and such a low RTD is particularly desirable.

Sample No. 15 is a particularly good example of how the various parameters described in the present invention can be correctly selected to obtain a filter and corresponding aerosol article having particularly desirable characteristics.

Thus, methods, systems, devices, assemblies and products for filters having increased hardness are described. Various modifications and variations of the present invention will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. Although the present invention has been described in connection with specific preferred embodiments, it should be understood that the claimed invention should not be unduly limited to such specific embodiments. In this regard, various modifications of the described embodiments of the present invention, which are obvious to experts in the mechanical fields, chemical fields and in the field of manufacturing aerosol generating products or related fields, claim to be included in the scope of the following claims.

Claims (17)

1. An aerosol-generating article, comprising: an aerosol-forming substrate; and a filter located downstream of the aerosol-generating substrate, moreover, the filter contains a filter material and has a drag resistance of less than 3.3 mm w.c. per mm filter length, and wherein the aerosol generating article has an average radial hardness of 95.5% to 99% as measured around the circumference of the filter. 2. An aerosol-generating article according to claim 1, wherein the filter material comprises filaments. 3. An aerosol generating article according to claim 2, wherein the filaments have a linear density of 4 denier or more. 4. The aerosol generating article of claim 2, wherein the filaments have a denier of 5 denier or more. 5. An aerosol generating article according to any one of claims 2 to 4, wherein the filter material contains cellulose acetate. 6. An aerosol generating article according to any one of claims 1 to 5, wherein the filter contains a plasticizer. 7. An aerosol generating article according to claim 6, wherein the filter contains from 7.5% by weight to 11.5% by weight of a plasticizer relative to the weight of the filter material. 8. An aerosol generating article according to claim 6 or 7, wherein the plasticizer is triacetin. 9. An aerosol generating article according to any one of claims 1 to 8, wherein the filter comprises a ficell located around the filter material. 10. An aerosol generating article according to claim 9, wherein the ficell contains paper having a basis weight of 50 grams per square meter or more. 11. The aerosol generating article of claim 9, wherein the ficell contains paper having a basis weight of 110 grams per square meter or less. 12. An aerosol generating article according to any one of claims 1 to 11, wherein the quotient of the filter draw resistance value divided by the mean radial hardness value of the aerosol generating article is 0.75 mm w.c./% or less. 13. An aerosol-generating article according to any one of claims 1 to 11, wherein the quotient of the filter draw resistance value divided by the mean radial hardness value of the aerosol-generating article is 0.65 mm w.c./% or less.

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