BR112020010454A2 - firm filter for aerosol generating article - Google Patents

Abstract

The present invention relates to an aerosol-generating article (10) includes an aerosol-forming substrate (20) and a filter (30) downstream of the substrate. The filter comprises filter material with filaments that are distributed over a filter cross section. The filter material comprises from about 7.5% by weight to about 11.5% by weight of plasticizer or from about 10.5% by weight to about 15% by weight of plasticizer. Filters can be difficult, maintaining adequate drag resistance.

Description

Descriptive Report of the Invention Patent for "FIRM FILTER FOR AEROSOL GENERATING ARTICLE".

[0001] The present invention relates to aerosol generating articles and filters for aerosol generating articles that have improved hardness.

[0002] Aerosol-generating articles include articles that can be burned to produce an aerosol or heated, but not burned to produce an aerosol, as well as articles that can aerosolize a substrate or composition in any other suitable manner , such as by chemical reaction or by particles in the air. Regardless of the mechanism for aerosol formation, aerosol generating articles may include a filter downstream of an aerosol forming substrate to filter one or more aerosol constituents.

[0003] For example, articles that generate combustible aerosol, such as cigarettes, usually have chopped tobacco, usually in the form of cut filler, surrounded by a paper wrapper that forms a tobacco rod. A cigarette is used by a smoker, lighting one end of the cigarette and burning the tobacco column. The smoker then receives the main stream of smoke when inhaling at the opposite end or mouth end of the cigarette, which typically contains a filter. The filter is positioned to trap some constituents of the main smoke before the main smoke is delivered to a smoker.

[0004] Filters on aerosol-generating articles generally include filter material surrounded by an enclosure. The plug housing contributes to the stiffness of the filter. Wrappers with improved stiffness, such as wrappers formed from heavier paper, can be used to produce firmer, stiffer filters. Buffer wraps with improved stiffness can help, for example, the removal of combustible aerosol-generating articles due to improved longitudinal stiffness and can result in the perception of a higher quality product when collected by a consumer due to radial toughness. enhanced.

[0005] However, circumscribing a rigid plug wrap around the filter material can present challenges. For example, the equipment on the filter's manufacturing lines may need to be changed so that the stiffer housing can be wrapped around the filter material.

[0006] Another option to increase the hardness of the filter may be to increase the fiber weight of the filter material used. That is, the density of the filter material can be increased. However, increasing the density of the filter material can increase filtration efficiency and prevent a desired amount of aerosol constituents from passing through the filter, resulting in an unexpected or unwanted taste or experience. The drag resistance of an aerosol generating article employing higher density filter material can also be undesirably increased compared to the article employing more standard density filter material.

[0007] It is desirable to provide a filter for use in an aerosol-generating article, in which the filter has improved hardness. Preferably, the filter maintains the desired characteristics, such as filter efficiency and resistance to stretching.

[0008] In various aspects of the present invention, an aerosol generating article is provided comprising an aerosol-forming substrate and a filter downstream of the substrate. The filter comprises filter material with filaments that are distributed over a filter cross section. The filter material comprises from about 7.5% by weight to about 11.5% by weight of plasticizer or from about 10.5% to about 15% by weight of plasticizer.

[0009] As described here, the filter material with about

7.5% by weight to about 11.5%, or from about 10.5% to about 15% by weight of plasticizer may result in filters and aerosol generating articles | which contain filters that have desirable hardness while maintaining other desirable filter properties, such as leak resistance and filtration efficiency.

[0010] The incorporation of improved hardness filters in aerosol-generating articles can allow aerosol-generating articles to be perceived as of higher quality. The improved hardness of the filter can also be advantageous when, for example, the butt of a combustible aerosol-generating article, such as a cigarette, is reached, including the filter. For example, an improved hardness filter can keep the user's fingers away from the burnt end of the cigarette when the cigarette is extinguished, because the filter is less likely to bend during the cigarette's quenching process. However, previously it was difficult to obtain more rigid filters that maintained desirable characteristics, such as drag resistance.

[0011] The advantages discussed above, as well as other advantages, will be readily evident to those skilled in the art when reading and understanding the present disclosure.

[0012] The aerosol generating articles of the present invention can have any suitable medium radial hardness. Preferably, aerosol-generating articles have an average radial hardness of 95% or greater when measured around the filter, which was previously not possible, maintaining the desired properties of the filter, such as resistance to stretching. For example, aerosol-generating articles may have an average radial hardness of 96% or greater, 97% or greater or 98% or greater when measured around the filter. Preferably, aerosol-generating articles | have an average radial hardness of about 95% to about 99% when measured around the filter. As used here, the term "radial hardness" refers to the compressive strength is a direction transverse to a longitudinal axis. The radial hardness of an aerosol-generating article around a filter can be determined by applying a load across the article at the location of the filter, transversal to the longitudinal axis of the article and measuring the depressed average (average) diameters of the articles. Radial hardness is given by: Radial hardness (%) = Da * 100% D; where ds is the original diameter (uncompressed) and Da is the diameter reduced after applying a defined load for a defined period. The stiffer the material, the closer to 100% the stiffness.

[0013] To determine the hardness of a portion (such as a filter) of an aerosol article, the aerosol generating articles must be aligned in parallel in a plane and the same portion of each aerosol generating article to be tested must be subjected to a defined load for a defined duration. This test is performed using a well-known DD60A Densimeter device (manufactured and commercially available by Heinr. Borgwaldt GmbH, Germany), which is equipped with a metering head for aerosol-generating articles, such as cigarettes, and with a aerosol generating article.

[0014] The load is applied using two loads applying cylindrical rods, which extend over the entire diameter of all aerosol generating articles at once. According to the standard test method for this instrument, the test must be carried out so that there are twenty points of contact between the aerosol generating articles | and the load that applies cylindrical rods. In some cases, the filters to be tested may be long enough that only ten aerosol-generating articles | are required to form twenty points of contact, with each smoking article coming into contact with the two charge rods (because they are long enough to extend between the rods). In other cases, if the filters are too short to achieve this, then twenty aerosol generating articles should be used to form the twenty points of contact, with each aerosol generating article | contacting only one of the load application rods, as discussed below.

[0015] Two additional stationary cylindrical rods are located under the aerosol generating articles, to support the aerosol generating articles and neutralize the load applied by each of the loads that apply cylindrical rods.

[0016] For the standard operating procedure for such a device, a general load of 2 kilos is applied for the duration of 20 seconds. After 20 seconds (and with the load still applied to the smoking articles), the depression in the cylindrical rods for applying the load is determined, and then used to calculate the stiffness of the above equation. The temperature is maintained in the region of 22 degrees Celsius, + 2 degrees. The test described above is called the DD60A Test. The standard way to measure filter hardness is when the aerosol-generating article has not been consumed. Additional information on measuring mean radial hardness can be found in, for example, US Patent Application Publication 2016/0128378.

[0017] In some preferred examples, the filters of the present invention have an average radial hardness of 90% or more, such as 92% or more or 94% or more. For example, the filters of the present invention can have an average radial hardness of 95% or more, such as 95.5% or more. Most preferably, the filters have an average radial hardness of 96% or more, such as 97% or more. For example, the filters of the present invention can have an average radial hardness in the range of about 95% to about 99%, such as from about 95% to about 98%.

[0018] As used herein, "diameter" is used to describe the maximum dimension in the transverse direction (transverse to the longitudinal axis) of the filter or of an aerosol generating article that includes the filter. The longitudinal axis of the filter or aerosol generating article is in the direction of the length of the filter or aerosol generating article. For the purposes of the present disclosure, the term "radius" refers to a transverse distance from the longitudinal axis to an edge of the filter or article generating aerosol. Typically, the filter and the aerosol generating article! will have a cylindrical shape. However, the filter, aerosol-generating article or filter and aerosol-generating article need not be cylindrical in shape.

[0019] Aerosol-generating articles, including filters of the present invention, may have any resistance to adequate puff (RTD). "Puff resistance" refers to the difference in static pressure between the two ends of a sample when it is traversed by an air flow under stable conditions in which the volumetric flow is 17.5 milliliters per second at the outlet end. The RTD of a sample can be measured using the method established in ISO 6565: 2002. Preferably, aerosol-generating articles, including filters of the present invention, have an RTD similar to conventional cigarettes.

[0020] In some preferred examples, aerosol-generating articles, including filters of the present invention, have an RTD of about 40 mm of water column (mmMWG) and about 200 mmMWG, Preferably between about 50 MmmMWG is about 140 mmWG and, more preferably, about 50 MmMWG to about 100 mmWG. Preferably, the filters have an RTD of 90 mmWG or less, such as 70 MMWG or less. Most preferably, the filters have an RTD of 65 MmMWG or less, such as 60 mmWG or less.

[0021] The filter can have an RTD for the length of the rod used in the aerosol generating article, of about 40 mm of water column (mmMWG) and about 200 mmWG, preferably between about 50 mmWG and about 140 mmWG and, more preferably, from about 50 mmWG to about 100 mmWG. The filter, in the length used in the aerosol generating article, can have an RTD of 90 mmWG or less, such as 70 mmWG or less. Most preferably, the filters have an RTD of 65 mmWG or less, such as 60 mmWG or less.

[0022] The filter material of the invention preferably has an RTD for a rod length of 126 mm from about 40 mm water meter (mmMWG) and about 200 mmMWG, preferably between about 50 mmMWG and about 140 mMmmMWG and, more preferably, from about 50 MmMWG to about 100 mmWG. Preferably, the filters have an RTD of 90 mmWG or less, such as 70 MMWG or less. Most preferably, the filters have an RTD of 65 MmMWG or less, such as 60 mMmMWG or less. Preferably, the filter has a rod length of 126 mm, an RTD of 90 mMMWG or less, such as 70 MmMWG or less. Most preferably, the filters have a rod length of 126 mm, an RTD of 65 MmMWG or less, such as 60 mmWG or less.

[0023] In some preferred embodiments, the filter material of the invention has an RTD for a stem length of about mm to about 40 mm, such as about 21 mm, from about 40 mm of water column ( mmMWG) to about 200 mmWG, preferably between about 50 MmMWG and about 140 mmWG, and more preferably from about 50 MmMWG to about 100 mmWG. Preferably, filters have an RTD of 90 mmWG or less, such as 70 MMWG or less. Most preferably, the filters have an RTD of 65 MMWG or less, such as 60 mmWG or less. Preferably, the filter has a rod length of about 15 mm to about 40 mm, such as about 21 mm, an RTD of 90 mmWG or less, such as 70 MmMWG or less, 65 mmWG or less, or 60 mmWG or less .

[0024] Filters with shorter lengths may have a lower RTD than filters with longer lengths, especially if the filters

others are made of the same material in the same way. In some preferred embodiments, filters with a rod length of about 15 mm to about 40 mm, such as about 21 mm, have an RTD of about 30 mmWG to about 90 mMmmMWG, about 40 MMWG about 70 mMmmMWG, about 40 MmmMWG to about 65 MMWG or about 40 MmMWG to about 60 MmMWG.

[0025] Preferably, the filters have an RTD of 90 mmWG or less, such as 70 mMmWG or less, 65 MmMWG or less or 60 mmMWG or less for a filter length of 21 mm. That is, the filters have an RDT of about 4.3 MmMWG or less, 3.3 MmMWG or less, 3.1 MmMWG or less or 2.9 mmWG or less per mm of filter length.

[0026] Filters and associated aerosol-generating articles may have any suitable relationship between RTD and medium radial hardness. For example, the quotient of the RTD value of the filter divided by the average radial hardness value of the aerosol generating article is 0.75 or less. Preferably, the quotient of the RTD value of the filter divided by the average radial hardness value of the aerosol generating article is 0.7 or less. More preferably, the quotient of the RTD value of the filter divided by the value of the average radial hardness of the aerosol generating article | is 0.65 or less.

[0027] The filters and articles associated with aerosol generators may have some value suitable for (100-hardness) xRTD, where the hardness is the average radial hardness value (%) and RTD is the RTD value in mmW € G. For example, filters and associated aerosol generating articles may have a value for (hardness 100) xRTD in a range of about 40 to about 2000. Preferably, the associated aerosol generating filters and articles have a value for (hardness) 100) XxRTD in a range of about 40 to about 1000; more preferably from about 40 to about 500.

[0028] Filters and associated aerosol-generating articles can have any suitable value for [(hardness 100) X: RTD] / mm of filter, where (hardness 100) xRTD is the one defined above and mm of filter is the length of the filter. Preferably, the filters have a value for [(hardness 100) xRTD] / mm of filter of 20 or less; more preferably 15 or less; and even more preferably, 10 or less. For example, filters can have a value for [(hardness 100) XkRTD] / mm of filter from about 2 to about 20; Preferably from about 3 to about 15; and more preferably from about 5 to about 13.

[0029] The filters of the invention can achieve a suitable hardness and resistance to stretching, incorporating adequate amounts of filter material with suitable filament size and plasticizer concentration, as well as selecting buffer wrapper with appropriate characteristics.

[0030] Any suitable filter material can be used in accordance with the present invention. Examples of suitable filter material include cellulose esters, such as cellulose acetate, polylactic acid (PLA), cellulosic material, polypropylene or any degradable filtration medium, or a combination or mixture of two or more filter materials. In preferred embodiments, the filter material includes polymeric filter material, such as polylactic acid, cellulose esters and mixtures thereof. Preferably, the filter material includes a cellulose ester. Examples of cellulose esters that can be used to form filter material include cellulose acetates, cellulose propionates and cellulose butyrates with varying 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 comprises cellulose acetate.

[0031] The filter material comprises filaments that are distributed along a cross section of the filter. As used herein, a 'cross section' is a section that is transversal to the longitudinal axis. Preferably, the filaments are present at a similar density along the cross section of the filter. A hollow tube formed from filter material would not be considered to have filaments distributed over a filter cross section, because there would be no filaments in the middle of the cross section.

[0032] The filter material, including the plasticizer, can have any suitable fiber weight or density. Preferably, the filter material weighs between about 5 mg / mm and about 7 mg / mm. More preferably, the filter material has a weight between about 5.5 mg / mm and about 6.5 mg / mm. Preferably, the filter has a density between about 0.11 g / one hundred? and about 0.2 g / in ?. Preferably, the filter has a density between about 0.12 g / cmº? and about 0.19 g / in ?, such as between about 0.12 g / cm? and about 0.15 g / in * ?. Filters with higher weights and densities tend to be more rigid than those with lower weights and densities. However, increasing the weight or density of the filter material can also tend to increase the RTD to undesirable levels or can filter too much aerosol | and thus prevent a sufficient amount of aerosol from being delivered to the user.

[0033] To mitigate the effects of increasing the weight or density of the filter on RTD and filtration, filters can comprise filaments with a linear density of 4 denier per filament or more. The linear density of the filaments used in the filters can be measured by determining the mass, in grams, of the filaments per 9000 meters. Preferably, the filters of the present invention comprise filaments with a linear density of 5 denier per filament or greater, 6 denier or greater or 7 denier or greater. For example, the filters of the present invention can comprise filaments with a linear density of about 8 denier per filament. Preferably, the filaments with linear densities described above are cellulose acetate filaments.

[0034] The filters of the present invention can have any suitable amount of plasticizer. As used here, a "plasticizer" is a solvent that, when applied to polymeric fibers, bonds the fibers together. Examples of plasticizers include triacetin (also known as glycerol triacetate), diethylene glycol diacetate, triethylene glycol diacetate, tripropion, triethylacetyl citrate, triethyl citrate and mixtures of one or more of these. Preferably, the plasticizer comprises triacetin. One or more plasticizers can be mixed with, for example, polyethylene glycol and placed in contact with the polymer fibers to join the fibers together. The fibers can be brought into contact with a bonding agent in any suitable way. Preferably, a composition comprising the binding agent is sprayed onto the polymeric fibers.

[0035] The filters of the present invention comprise from about 7.5% to 11.5% of plasticizer, in relation to the weight of the filter material. For example, filters can comprise from about 7.5 g to about 11.5 g of plasticizer per 100 g of filter material. Preferably, the filters comprise about 7.5% to 11% plasticizer or about 7.5% to about 10% plasticizer. For example, the filter can comprise from about 8% to 11% plasticizer or from about 8% to about 10% plasticizer.

[0036] Preferably, the filters of the present invention comprise from about 10.5% to about 15% of plasticizer, in relation to the weight of the filter material. For example, filters can comprise from about 10.5 g to about 15 g of plasticizer per 100 g of filter material. Preferably, the filters comprise about 10.5%

to about 13% plasticizer, from about 11% to 13% plasticizer, from about 11.5% to about 13% plasticizer, from about 12% plasticizer to about 13% plasticizer or about 12.5% to about 13% plasticizer. More preferably, the filters comprise from about 10.5% to about 12.5% plasticizer or from 11% to 12.5% plasticizer. Even more preferably, the filters comprise from about 10.5% to about 12% plasticizer or from about 11% to 12% plasticizer. For example, filters can comprise from about 10.5% to about 11.5% plasticizer or from about 11% to about 11.5% plasticizer.

[0037] Many commercially available cigarette filters include about 5-7% plasticizer. As shown here, filters with concentrations of plasticizer according to the invention may have improved filter characteristics. Thus, filters with plasticizer concentrations higher than those of the filters of such cigarettes may be desired. Accordingly, the filters of the present invention have a plasticizer concentration of about 7.5% or more, about 10.5% or more, or about 11% or more.

[0038] The inventors have discovered that the specific amount of filter plasticizer of the invention can lead to a filter with desirable hardness, RTD and filtration efficiency. When the amount of plasticizer exceeds about 12%, especially if the plasticizer exceeds about 13%, the quality of the filter tends to suffer. For example, a cellulose acetate filter with more than about 12% triacetin results in the filter having relatively large voids in the filter, which can substantially reduce the filtration efficiency and make the filter unacceptable.

[0039] Preferably, the filter material comprises cellulose acetate. Preferably, the plasticizer comprises triacetin. Preferably, the filter material comprises cellulose acetate and the plasticizer comprises triacetin. The plasticizer in a range of about 7.5% to 11.5% by weight of the filter material is particularly relevant when the plasticizer is triacetin and the filter material is cellulose acetate.

[0040] The filter may include a buffer wrap around the filter material. The buffer housing can contribute to the hardness of the filter. The buffer wrap can be coated with any suitable coating composition to improve hardness. If the buffer wrapper includes a coating, the coating will preferably increase the radial hardness and longitudinal hardness of a filter that includes the coated buffer wrap.

[0041] Any coating composition suitable for improving hardness can be applied to the filter housing according to the present invention. Preferably, the coating composition that improves hardness does not result in a coating that adversely changes the perception of taste during the smoke of a tobacco product that includes the coated filter. In some preferred embodiments, a coating composition for improving hardness comprises one or more components, such as binders or other additives, used in the manufacture of cigarettes. For example, the coating composition can comprise a suitable binder used in cigarette paper, filter paper or buffer wrappers.

[0042] Examples of suitable materials that can be included in a coating composition to improve hardness are starch, polyacrylamide derivatives, styrene butadiene, acrylic styrene, dextrin, oxidized starch, ethylcellulose, acetylcellulose, carboxymethylcellulose, hydroxyethylcellulose or other derivatives suitable cellulose; pectins; guar gum; locust bean bran; agar; sodium alginate or other suitable alginates; and the like. In some preferred embodiments, a coating to improve hardness comprises polyvinyl alcohol.

[0043] Any suitable buffer wrap can be coated with a coating that improves hardness. Preferably, the buffer wrapper comprises, consists essentially of, or consists of, a paper wrapper.

[0044] The buffer wrapper can have any suitable weight. Preferably, the buffer wrapper weighs from about grams per square meter to about 180 grams per square meter. More preferably, the buffer wrapper has a weight of 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.

[0045] The buffer wrapper can be of any suitable thickness. Appropriate buffer wrap papers can have a thickness of about 25 micrometers to about 200 micrometers; Preferably from about 50 micrometers to about 200 micrometers. In some preferred embodiments, a buffer wrap has a thickness of about 100 micrometers to about 150 micrometers.

[0046] A buffer wrapper with heavier weight and thickness tends to be more rigid than a buffer wrapper with less weight and less thickness.

[0047] The buffer wrap may have adequate stiffness. The stiffness of a buffer wrap can be determined by ISO 2493-1: 2010: Paper and cardboard - Determination of flexural strength - Part 1: Constant deflection rate, ISO 2493-2: 2011: Paper and cardboard - Determination of flexural strength - Part 2: Tested in Taber type, or both ISO 2493-1: 2010 and ISO 2493-2: 2011. Preferably, the buffer housing has a rigidity in the machine direction with a flexing effect of 15º in a length of 10 mm (MD - 15º 10mm) of 100 mN.mm or greater. For example, the buffer wrap may have a stiffness (MD -

15º 10mm) from about 100 mN.mm to about 500 mN.mm. Preferably, the buffer housing has a stiffness (MD - 15º 10 mm) of about 120 mN.mm to about 450 mN.mm.

[0048] Preferably, the buffer housing has a transverse stiffness with a flexing effect of 15º over a length of 10 mm (CD - 15º 10mm) equal to or greater than 40 MN.mm. For example, the buffer wrap may have a stiffness (CD - 15º 10 mm) from about 40 mMN.mm to about 250 mN.mm. Preferably, the capped envelope has a stiffness (CD - 15º 10 mm) of about 50 MN.mm to about 200 mN.mm.

[0049] The buffer wrap may have any suitable porosity or it may even be non-porous. For example, the buffer wrap may have a relatively high porosity, such as greater than about 1,000 Coresta units or greater than about 5,000 Coresta units. In addition, or alternatively, the buffer wrap may have a porosity of less than about 10,000 Coresta units.

[0050] A filter of the present invention can include additional material, such as activated carbon; flavorings, which may be in the form of compounds, flavoring threads, beads, capsules or the like; or any other suitable material. The additional material can be embedded in the filter material or can be arranged in cavities between the plugs of the filter material in, for example, a buffer-space-buffer configuration. In such a configuration, a buffer wrap as described here can be particularly advantageous by adding improved structural toughness over the cavities.

[0051] The filters of the present invention can have any suitable dimensions. The filters are usually 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 between about 7.0 mm and about 8.0 mm, more preferably between about 7.7 mm and 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 incorporated.

[0052] The length of the filter (which is the total length of the filter, including the filtration material, measured in a direction substantially parallel to the longitudinal axis of the smoking article) may have any suitable value. However, it may be convenient for the filter length to be substantially the same diameter as conventional smoking articles. The length designates the total length of the filter, including the filter material plug. That is, if the filter comprises one or more filter segments in addition to the filter material plug, the length will be the total length of all filter segments and the filter material plug. If the filter comprises only the filter material plug, the length will be only the length of the filter material plug.

[0053] Longer filters tend to have a higher RTD than shorter filters.

[0054] Preferably, the filter has a length between about 15 mm and about 40 mm. Even more preferably, the filter has a length between about 18 mm and about 27 mm. In a fashion, the filter has a length of about 27 mm. In another mode, the filter has a length of about 21 mm.

[0055] The filters of the present invention are preferably formed using conventional filter making equipment. For example, the filter material can be formed from filament fiber bands using conventional equipment. The plasticizer can be incorporated using conventional equipment, and the capped wrapper can be placed on the filter using conventional equipment.

[0056] The filters of the present invention can be incorporated into any suitable aerosol generating article in any suitable manner. Preferably, the filter is incorporated into an aerosol generating article downstream of a substrate material that forms an aerosol. The term "downstream" refers to the relative positions of elements of the aerosol-generating article described in relation to the direction of the main aerosol, as it is swallowed from an aerosol-forming substrate and into the user's mouth.

[0057] The term "aerosol-generating article" includes cigarettes, cigars, cigarillos and other articles in which an aerosol-forming substrate, such as tobacco, is lit and burned to produce smoke. The term "aerosol-generating article" also includes articles in which an aerosol-forming substrate is not burned, such as, among others, aerosol-generating articles that directly or indirectly heat an aerosol-forming substrate, or aerosol-generating articles | that use airflow or chemical reaction, with or without a heat source, to deliver nicotine or other materials from the aerosol-generating substrate.

[0058] The filters of the present invention may be particularly desirable for use in heated tobacco articles, in which the aerosol forming substrate is not burned. Such articles often employ relatively short filters with low RTD. Filters on products that do not heat up are generally soft and can become softer during use as the aerosol flows through the filter. In some cases, filters can at least partially collapse or disassemble during use, which can negatively affect the consumer's perception of the quality of the article. Therefore, by incorporating filters of the present invention into heated tobacco articles employing relatively short filters with low RTD, the perceived quality of the article can be improved due to the rigidity of the filter and the lack of collapse and disassembly. Due to the increased stiffness and improved filter qualities, short filters that provide relatively low filtration can be used in heated tobacco articles, which can provide flavor and other sensory qualities similar to conventional smoking articles, such as cigarettes .

[0059] The filters of heated tobacco articles can be of any suitable length. For example, filters can be less than about 40 mm long, such as between about 10 mm and about 40 mm. Preferably, the filter has a length of less than about 30 mm, such as less than about 20 mm.

[0060] It now refers to the drawings, in which some aspects of the present invention are illustrated. It should be understood that other aspects not portrayed in the drawings are within the scope and spirit of the present invention. Schematic drawings are not necessarily to scale. Similar numbers used in the figures refer to components, steps and the like. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component to another figure labeled with the same number. In addition, the use of different numbers to refer to components in different figures is not intended to indicate that different numbered components cannot be the same or similar to other numbered components.

[0061] FIG. 1 is a schematic perspective view of an embodiment of a partially unwrapped aerosol-generating article having a filter 30. The aerosol-generating article 10, a cigarette in the embodiment depicted, is shown as partially unwrapped only to illustrate representative components of the article . The aerosol-generating article 10 includes an aerosol-forming substrate rod 20, such as a tobacco rod and a filter 30 downstream of the aerosol-forming substrate 20. Filter 30 and rod 20 are coaxially aligned with the longitudinal axis of the aerosol generating article | 10,

which axis is represented by the line A-A. The aerosol generating article | shown 10 includes a buffer wrap 60, cigarette paper 40 filter paper 50. Cigarette paper 40 circumscribes at least a portion of column 20. Filter paper 50 or other suitable wrap circumscribes buffer wrap 60 and a portion cigarette paper 40 as is generally known in the art. Filter 30 includes buffer housing 60 and filter material 32.

[0062] The examples of the described modalities are not limiting. Other modalities consistent with the examples of modalities described above will be evident to those skilled in the art.

[0063] All scientific and technical terms used in this document have meanings commonly used in the art, unless otherwise specified. The definitions provided in this document are to facilitate the understanding of certain terms used frequently in this document.

[0064] As used in this document, the singular forms "one", "one" and "the (a)" encompass the modalities with plural referents, unless the content clearly indicates otherwise.

[0065] As used in this document, "or" is generally used in its sense including "and / or", unless the content clearly indicates otherwise. The term "and / or" means one or all of the listed elements or a combination of two or more of the listed elements.

[0066] As used herein, "having", "having", "includes", "including", "comprises", "comprising" or similar are used in their open sense, and generally mean "including, but not limited to" limiting itself to ". It will be understood that "consisting essentially of", "consisting of" and the like are included in "comprising" and the like.

[0067] The words "preferential" and "preferentially" refer to the modalities of the invention that can have certain benefits, under certain circumstances. However, other modalities may also be preferred, under the same or other circumstances. In addition, reporting one or more preferred modalities does not imply that other modalities are not useful and is not intended to exclude other modalities from the scope of the disclosure, including claims.

EXAMPLES

[0068] The following is a non-limiting example that illustrates the selection of the weight of the filter material, the percentage of the weight of the plasticizer and the linear density of the filament and the properties of the buffer housing that resulted in improved filter hardness. . Twelve-nine filters were made with cellulose acetate fiber (y-shaped fibers) with different linear filament densities and different amounts of plasticizer (triacetin). The resulting filter material was wrapped with bands with different bases and thicknesses of weight. The resulting filter rods had a diameter of 7.71 mm and a length of 126 mm. The materials used to manufacture some of the nineteen filters are shown below in Table 1. Table 1: Components of the tested filters [weight tmeards fame (denien | 5 | sa [94/54 | a | |)

[0069] The mean radial hardness of the 126 mm long filter rods was determined as described in the US patent application publication number 2016/0128378. The RTD of the 126 mm long filter rods was measured according to the ISO 6565: 2002 standard. The enclosure stiffness was measured according to ISO 2493-1: 2010 and ISO 2493-2: 2011. For some filters, it was determined

the weight of the filter and plasticizer material, as well as the density of the heavy material (based on the diameter of 7.71 mm). The results are shown in Table 2 below. Table 2: Properties of fiber filters + plasticizer weight 706.2 | 7281 (mg) paper stiffness - MD - | 135 135 323 323 323 323 323 15º 10 mm (mMN.mm) paper stiffness - CD - [75 75 165 165 165 165 165 15º 10 mm (MN.mm) Percent of hardness | 92,200 | 94,650 | 95,413 | 95,827 | 95,963 | 96,460 | 97,373 dial ora [5 To Tm fm fes es Te)

[0070] As shown in Table 1 and Table 2, increasing the plasticizer weight percentage from 7% to 10% increases the radial hardness without substantially increasing the RTD. Compare, for example: Filter 4 with Filter 5; and Filter 12 with Filter 13. In other words, increasing the level of plasticizer within the limits of the present invention can provide a higher hardness without significantly affecting the RTD.

[0071] Note that the RTD is tested on filters with a length of 126 mm, which can be longer than those that can be used in some aerosol generating articles. For illustrative purposes, filter 15 had an RTD of 255 mmWG, which is an RTD per mm of about 2.02, which would be expected to result in an RTD of about 42.5 mmWG for a filter with a length of 21 mm. Thus, a 21 mm long filter for filter 15 is expected to have an average radial hardness of 97.607% (as the length should not substantially affect the radial hardness), although it has a low RTD of around 42, 5 MmmMW € G.

[0072] A filter with such a high hardness and such a low RTD is particularly desirable.

[0073] Thus, methods, systems, devices, sets and articles for filters with improved hardness are described. Various modifications and variations of the invention will become apparent to individuals skilled in the art without incurring a departure from the scope and spirit of the invention. Although the invention has been described in connection with specific preferential modalities, it should be understood that the invention, as claimed, should not be excessively limited to such modalities. In fact, several modifications to the modes described for carrying out the invention, which are evident to those skilled in mechanical techniques, chemical techniques and the manufacture of aerosol-generating articles or related fields, must be within the scope of the following claims.

Claims (14)

1. Aerosol-generating article characterized by the fact that it comprises: an aerosol-forming substrate; and a filter downstream of the aerosol-forming substrate, where the filter includes filter material with filaments that are distributed over a filter cross-section, where the filter material has a density of 0.11 g / cm? or greater, and wherein the filter material includes from about 10.5% by weight to about 15% by weight of plasticizer. 2. Aerosol-generating article according to claim 1, characterized in that the filter material comprises from about 10.5% by weight to about 11.5% by weight of plasticizer. 3. Aerosol-generating article, according to claim 1 or 2, characterized by the fact that the plasticizer comprises triacetin. Aerosol-generating article according to any one of claims 1 to 3, characterized in that the filaments comprise cellulose acetate filaments. Aerosol-generating article according to any one of claims 1 to 4, characterized in that the filaments have a linear density of 4 denier per filament or more. Aerosol-generating article according to any one of claims 1 to 4, characterized in that the filaments have a linear density of 5 denier per filament or more. Aerosol-generating article according to any one of claims 1 to 6, characterized in that the filter material has a density between about 0.12 g / rem? and 0.19 g / cm ?. Aerosol-generating article according to any one of claims 1 to 7, characterized in that the filter comprises a buffer housing disposed on the filter material. 9. Aerosol-generating article according to claim 8, characterized by the fact that the filter further comprises a hardness-enhancing coating on the buffer housing. 10. Aerosol-generating article according to claim 9, characterized by the fact that the coating comprises polyvinyl alcohol. 11. Aerosol-generating article according to any one of claims 1 to 10, characterized in that the filter has an average radial hardness of 95% or more, in which the average radial hardness is measured by applying a load of 2 kg for 20 seconds around the filter of the aerosol generating article and comparing the relation of the original uncompressed diameter with the diameter after the load is applied. Aerosol-generating article according to any one of claims 1 to 11, characterized in that the filter has a drag resistance of 90 MmMWG or less. 13. Aerosol-generating article according to any one of claims 1 to 11, characterized in that the filter has a drag resistance of 70 MMWG or less. Aerosol-generating article according to any one of claims 1 to 13, characterized in that the aerosol-generating substrate comprises tobacco.