WO2023196840A1

WO2023196840A1 - Hollow acetate tube filters having high hardness values

Info

Publication number: WO2023196840A1
Application number: PCT/US2023/065363
Authority: WO
Inventors: Pablo VERDU BLASCO
Original assignee: Eastman Chemical Company
Priority date: 2022-04-08
Filing date: 2023-04-05
Publication date: 2023-10-12

Abstract

A filter product for use in a consumer product. The consumer product may comprise a tobacco product, such as a combustible cigarette or a heat- not-burn stick. The filter product may comprise a plurality of cellulose acetate fibers having hollow core sections.

Description

HOLLOW ACETATE TUBE FILTERS HAVING HIGH HARDNESS VALUES

FIELD OF THE INVENTION

[001 ] The present invention is related to the field of filters. More specifically, the present invention is related to filter products formed from fibers having hollow cores, with such filter products being configured for use in consumer products.

DESCRIPTION OF RELATED ART

[002] As discussed in more detail below, various types of consumer products, such as tobacco products, require the use of filters. Typical tobacco product filters, e.g., cigarette filters, are made from continuous-filament tow bands of cellulose acetate-based fibers, generally called cellulose acetate tow (sometimes referred to herein as “CA tow”). The use of CA tow to make filters is described in various patents, and the CA tow may be plasticized. See, for example, U.S. Pat. No. 2,794,239. Instead of continuous fibers, staple fibers may be used which are shorter, and which may assist in the ultimate degradation of the filters. See, for example, U.S. Pat. No. 3,658,626 which discloses the production of staple fiber filter elements directly from a continuous filamentary tow. These staple fibers also may be plasticized.

[003] CA tow for combustible cigarette filters is typically made up of solid cross-sectioned, small-filament-denier fibers which are intentionally highly crimped and entangled, as described in U.S. Pat. No. 2,953,838. Such fibers would generally have a solid cross-section that is, e.g., (i) “Y” shaped, or (ii) round/circular shaped. In constructing a filter, the crimp of the fibers allows improved filter firmness and reduced tow weight for a given pressure drop. The conversion of CA tow into tobacco product filters may be accomplished by means of a tow conditioning system and a plug maker, as described, for example, in U.S. Pat. No. 3,017,309. The tow conditioning system withdraws the CA tow from a bale, spreads and de-registers (“blooms”) the fibers, and delivers the tow to the plug maker. The plug maker compresses the tow, wraps it with plugwrap paper, and cuts it into rods of suitable length. Once formed, such plug-type filters are generally shaped as rods or cylindrical rods, with the cellulose acetate fibers being present through the interior of the rods so as to form a solid cross-section. In some alternatives, filters may be formed as hollow cylinders or tubes, with the cellulose acetate fibers being present only through a portion of the interiors of the tubes so as to form a hollow cross-section. Specifically, such hollow tubes may include an interior diameter and an exterior diameter, with a wall thickness extending between the interior and exterior diameters. Thus, the cellulose acetate fibers are generally present throughout the wall of the hollow tubes (i.e. , between the interior and exterior diameters).

[004] It is generally understood that filters are one of the most expensive components of tobacco products. However, the presence of filters is necessary so as to at least partially remove undesirable volatile particles or other particulate materials from tobacco smoke and aerosols. As such, a common suggestion for reducing the costs of tobacco product filters is to reduce the amount of CA tow or fibers within the filters. Unfortunately, reducing the amount of CA tow or fibers within filters has previously resulted in undesirable filter properties, particularly when using common, Y-shaped fibers. For example, reducing the amount of CA tow or fibers in filters has been found to result in filters that are too soft (i.e., have lower hardness/rigidity) and that have inconsistent structural formation resulting in unacceptable visual defects. Similarly, reducing the amount of CA tow or fibers in filters has been found to result in unacceptably low pressure drops through the filters during use of the tobacco products.

[005] Another proposed option for reducing costs associated with filters is to increase manufacturing speed of the filters, thereby reducing overall downtime and costs. However, due to high frictional characteristics of commonly-used fibers (e.g., Y-shaped fibers), increasing manufacturing speed has been found to result in increased maintenance and/or malfunction of the manufacturing machines, as well as increased structural defects in the filters.

[006] In view of the above, there remains a need in the art for the development of a consumer product filter that can be produced at reduced cost, but which does not exhibit unacceptable functional or aesthetic characteristics. More specifically, there is a need in the art for the development of a consumer product filter that can be produced with less fiber, but which exhibits appropriate levels of hardness, pressure drops, and manufacturing quality.

SUMMARY

[007] One aspect of the present invention concerns a filter product for use in a consumer product. The filter product comprises a plurality of cellulose acetate fibers that include hollow core sections. The fibers have, on average, an area moment of inertia of at least 50,000 pm⁴.

[008] Another aspect of the present invention concerns a filter product for use in a consumer product. The filter product comprises a plurality of cellulose acetate fibers, with the fibers including hollow core sections. The fibers have a fiber-to-metal coefficient of friction of no more than 0.565.

[009] Another aspect of the present invention concerns a filter product for use in a consumer product. The filter product comprises a plurality of cellulose acetate fibers, with the fibers including hollow core sections. The fibers have a fiber-to-fiber coefficient of friction of no more than 0.135.

[010] Another aspect of the present invention concerns a consumer product comprising tobacco and a filter product. The filter product comprises a plurality of cellulose acetate fibers having hollow core sections.

[011 ] Another aspect of the present invention concerns a combustible cigarette comprising tobacco and a filter product. The filter product comprises a plurality of cellulose acetate fibers having hollow core sections.

[012] Another aspect of the present invention concerns a heat-not-burn stick comprising tobacco and a filter product. The filter product comprises a plurality of cellulose acetate fibers having hollow core sections.

[013] Another aspect of the present invention concerns a filter product for use in a consumer product. The filter product comprises a hollow tube formed from a plurality of cellulose acetate fibers, with the fibers including hollow core sections. The hollow tube includes an interior diameter and an exterior diameter. The mass of the cellulose acetate within the hollow tube is no more than 495 mg, and the hollow tube has a hardness of at least 92.0% (Borgwaldt 3Kg).

[014] Another aspect of the present invention concerns a filter product for use in a consumer product. The filter product comprises a hollow tube formed from a plurality of cellulose acetate fibers, with the fibers including hollow core sections. The hollow tube includes an interior diameter and an exterior diameter. The mass of the cellulose acetate within the hollow tube is no more than 495 mg, and the hollow tube has a hardness of at least 92.2% (Borgwaldt 3Kg).

[015] Another aspect of the present invention concerns a filter product for use in a consumer product. The filter product comprises a hollow tube formed from a plurality of cellulose acetate fibers, with the fibers including hollow core sections. The hollow tube includes an interior diameter and an exterior diameter. The mass of the cellulose acetate within the hollow tube is no more than 497 mg, and the hollow tube has a hardness of at least 92.4% (Borgwaldt 3Kg).

[016] Another aspect of the present invention concerns a filter product for use in a consumer product. The filter product comprises a cylindrical rod formed from a plurality of cellulose acetate fibers, with the fibers including hollow core sections. The mass of the cellulose acetate within the hollow tube is no more than 560 mg, and the hollow tube has a hardness of at least 83.0% (Borgwaldt 3Kg).

[017] Another aspect of the present invention concerns a filter product for use in a consumer product. The filter product comprises a cylindrical rod formed from a plurality of cellulose acetate fibers, with the fibers including hollow core sections. The mass of the cellulose acetate within the hollow tube is no more than 540 mg, and the hollow tube has a hardness of at least 83.5% (Borgwaldt 3Kg).

[018] Another aspect of the present invention concerns a filter product for use in a consumer product. The filter product comprises a cylindrical rod formed from a plurality of cellulose acetate fibers, with the fibers including hollow core sections. The mass of the cellulose acetate within the hollow tube is no more than 580 mg, and the hollow tube has a hardness of at least 84.5% (Borgwaldt 3Kg).

BRIEF DESCRIPTION OF THE DRAWINGS

[019] FIG. 1 is a lateral cross section of a solid, cylindrically-shaped rod filter for a tobacco product;

[020] FIG. 2 is a lateral cross section of a hollow, cylindrically-shaped hollow tube for a tobacco product;

[021 ] FIG. 3 is a longitudinal cross section of a combustible cigarette with a filter product in the form of a solid, cylindrically-shaped rod filter at a mouth end of the cigarette;

[022] FIG. 4 is a longitudinal cross section of a combustible cigarette with a filter product having a solid, cylindrically-shaped rod filter at a mouth end of the cigarette;

[023] FIG. 5 is a longitudinal cross section of a combustible cigarette with another filter product having a solid, cylindrically-shaped rod filter at a mouth end of the cigarette;

[024] FIG. 6 is a longitudinal cross section of a combustible cigarette with a filter product having a hollow, cylindrically-shaped hollow tube at a mouth end of the cigarette and a solid, cylindrically-shaped rod filter positioned between the hollow, cylindrically-shaped filter and a tobacco section;

[025] FIG. 7 is a longitudinal cross section of a combustible cigarette with another filter product having a hollow, cylindrically-shaped hollow tube at a mouth end of the cigarette and a solid, cylindrically-shaped rod filter positioned between the hollow, cylindrically-shaped filter and a tobacco section;

[026] FIG. 8 is a longitudinal cross section of a heat-not-burn stick with a filter product having a solid, cylindrically-shaped rod filter at a mouth end of the heat-not-burn stick; [027] FIG. 9 is a longitudinal cross section of a heat-not-burn stick with another filter product having a solid, cylindrically-shaped rod filter at a mouth end of the heat-not-burn stick;

[028] FIG. 10 is a longitudinal cross section of a heat-not-burn stick with another filter product having a solid, cylindrically-shaped rod filter at a mouth end of the heat-not-burn stick and a hollow, cylindrically-shaped hollow tube positioned between the solid, cylindrically-shaped filter and a tobacco section;

[029] FIG. 1 1 is a longitudinal cross section of a heat-not-burn stick with another filter product having a first hollow, cylindrically-shaped hollow tube at a mouth end of the heat-not-burn stick and a second hollow, cylindrically- shaped hollow tube positioned between the first hollow, cylindrically-shaped hollow tube and a tobacco section;

[030] FIG. 12 is a longitudinal cross section of a heat-not-burn stick with another filter product having a solid, cylindrically-shaped rod filter at a mouth end of the heat-not-burn stick, a first hollow, cylindrically-shaped hollow tube positioned adjacent to the solid, cylindrically shaped rod filter, and a second hollow, cylindrically-shaped hollow tube positioned between the first hollow, cylindrically-shaped hollow tube and a tobacco section;

[031 ] FIG. 13 is a lateral cross section of a fiber/filament having a closed C shape;

[032] FIG. 13A is a lateral cross section of another fiber/filament having a closed C shape;

[033] FIG. 13B is a lateral cross section a fiber/filament not having a closed C shape;

[034] FIG. 14 is the lateral cross section of the fiber/filament from FIG. 13, further illustrating the principal moments of inertia of the fiber/filament;

[035] FIG. 15 is a pressure drop capability curve for three sets of rod filters having various cross-sectional shapes;

[036] FIG. 16 is a hardness capability curve for three sets of rod filters having various cross-sectional shapes; and

[037] FIG. 17 is a hardness capability curve for three sets of hollow tubes having various cross-sectional shapes. DETAILED DESCRIPTION

Glossary

[038] Cigarette - a thin cylinder of finely cut tobacco rolled in paper for smoking by a user.

[039] Denier per filament - a unit of textile measurement corresponding to the weight in grams of a 9,000 meters length individual filament.

[040] Fiber - a single filament.

[041 ] Fiber-to-fiber Coefficient of Friction - a ratio of the frictional force resisting the motion of two fiber surfaces in contact to the normal force pressing the two surfaces together.

[042] Fiber-to-metal Coefficient of Friction - a ratio of the frictional force resisting the motion of two surfaces, specifically a fiber surface and a metal surface, in contact to the normal force pressing the two surfaces together.

[043] Filament - a slender, continuous wire-like object.

[044] Filter Product - a single component, or two or more components forming an assembly, which is/are used individually, or in conjunction with other components, to primarily perform a filtration function. It is noted that although filter products are primarily used to perform filtration functions, filter products (or certain component thereof) may perform other functions, such as temperature management or pressure regulating functions.

[045] Rod Filter - a cylindrical rod formed from a plurality of fibers.

[046] Hollow Tube - a hollow cylinder in which the wall of the cylinder is formed by a plurality of fibers.

[047] Heat-not-burn stick - a non-combustible, multi-segmented assembly that uses precisely controlled heat to vaporize material to generate an aerosol that can be consumed by a user.

[048] Moment of Inertia - is a property of a cross-sectional shape or area that is used to predict deflection, bending and stress caused by loading. The moment of inertia is calculated with a multiple integral over the area. Specifically, principal moments of inertia of the area can be calculated at the centroid (pm⁴) in rectangular coordinates.

Ix = f_Ay² dA ly = x² dA for an area A located in the XY plane, with elemental area dA of coordinates (x,y). Moment of inertia may also be referred to as area moment of inertia, moment of inertia for an area, or second moment of area.

[049] Total Denier - a unit of textile measurement corresponding to the product of the denier per filament and the number of filaments in the tow or yarn.

[050] Tow - a band of multiple continuous filaments.

[051 ] Yarn - a bundle of filaments.

[052] The following embodiments of the present invention will be described in greater detail with reference to the accompanying drawings. While the drawings illustrate varied embodiments of the current invention, such figures and description are by way of example only. There is no intent to limit the principles and scope of the invention to the particularly described embodiment but instead is to be limited by the scope of the claims that follow.

[053] As used herein, any relational term, such as “first”, “second”, “top” or “upper”, “bottom” or “lower”, and the like, is used for clarity and convenience in understanding the disclosure and accompanying drawings, and does not connote or depend on any specific preference, orientation, or order, except where the context clearly indicates otherwise. As used herein, the terms “about” and "substantially" in reference to a given parameter, property, or condition means that the given parameter, property, or condition is met with a small degree of variance such as within acceptable measuring and/or manufacturing tolerances and generally includes a variability of up to 5% of the designated value. For example, a term of “about 1 .0” would include a variable range of from 0.95 to 1 .05. Any number in a sequence of numbers includes the adjective preceding or following the sequence. For example, at least 1 , 2, 3 deniers per filament (“dpf”) includes at least 1 dpf, or at least 2 dpf, or at least 3 dpf. All numbers or percentages relating to amounts of a substance within this description are given in weight percentages (wt.%), unless clearly defined to the contrary or otherwise clear from the context.

[054] Embodiments of the present invention are directed to filter products for consumer products. The term “consumer product” means generally any kind of product used by an end-user (e.g., a consumer) that permits the user to experience (e.g., inhale) an aerosolized substance. As such, consumer products may include tobacco products, botanical products, and/or the like. Tobacco products may include combustible products such as cigarettes, as well as non-combustible products such as heat-not-burn sticks, e-cigarettes etc. In these tobacco products, the kind of tobacco material used, e.g., tobacco, tobacco derivatives, expanded tobacco, reconstituted tobacco, tobacco substitutes, non-burnable products, etc., as well as mixtures thereof, is not particularly limited. Botanical products may comprise products configured to generate vaporized plant and/or other non-tobacco, biological-based substances.

[055] These consumer products may often be provided with a filter product in the form of a single filter element and/or a filter assembly. In some instances, the filter product may comprise a plug formed from fibrous material. In more detail, the plug may be shaped as a cylindrical rod (referred to herein as a “rod filter”). As illustrated in FIG. 1 , the fibrous material of a rod filter 10 may extend throughout the interior of the rod filter 10, such that the rod filter 10 has a generally solid cross-section. Rod filters 10 may be formed in various sizes, such as with exterior diameters “d_ext” from 4.00 to 10.00 mm, from 5.00 to 9.00 mm, and/or from 6.00 to 8.00 mm. For example, in some embodiments, rod filters 10 having exterior diameters d_ext greater than 7.00 mm may be considered “regular” sized. Rod filters 10 having exterior diameters dext from 6.00 to 7.00 mm may be considered “slim” sized. Furthermore, rod filters 10 having exterior diameters d_ext from 5.40 to 5.99 mm may be considered “microslim” sized.

[056] In addition to rod filters 10, certain tobacco products may incorporate filter products that include hollow, cylindrical tubes (referred to herein as “hollow tubes”). As illustrated in FIG. 2, a hollow tube 12 may comprise a hollow cylinder with an interior diameter “dint” and an exterior circumference “Cext”. The interior diameter will generally be non-zero, such that the hollow tube 12 surrounds an open, interior space. The wall of the hollow tube extends from the inner surface to the outer surface of the tube and, thus, has a thickness “T_waii.” The fibrous material of the hollow tube 12 will generally extend throughout the thickness T_waii of the wall of the hollow tube 12. As such, the hollow tube 12 has a generally hollow cross-section. Hollow tubes 12 may be formed in various sizes, such as with exterior circumferences “C_ext” from 12.0 to 28.00 mm, from 14.00 to 26.00 mm, from 16.00 to 24.00 mm, and/or from 18.00 to 22.00. Furthermore, the hollow tubes 12 may have wall thicknesses Twaii from 0.2 mm to 1 .8 mm, from 0.4 mm to 1 .6 mm, from 0.6 mm to 1 .4 mm, and/or 0.8 mm to 1 .2 mm. Although FIG. 2 illustrates the hollow tube 12 having a generally circular or cylindrical hollow interior space, it should be understood that hollow interior space may be formed with other shapes such as triangular, square, oval, moon-shaped, star-shaped, heart-shaped, or the like.

[057] The rod filters and hollow tubes 10, 12 may be used as filter products (in association with tobacco products) in various configurations, such as illustrated in FIGS. 3-1 1. For example, the rod filters 10 may be used individually as filters for tobacco products or, alternatively, as part of filter assemblies (i.e. , filters comprising multiple components) for tobacco products. The hollow tubes 12 will commonly be used as part of filter assemblies for tobacco products. Generally, hollow tubes 12 are intended to perform as a support element and to contribute to temperature management of the aerosol in heat-not-burn sticks and in cigarettes. Nevertheless, hollow tubes 12 may contribute to some filtration and pressure drop. In view of the above, it should be understood that the term “filter product,” as used herein, encompasses individual rod filters 10, individual hollow tubes 12, and assemblies that incorporate the rod filters 10 and/or hollow tubes 12.

[058] In more detail, FIGS. 3-7 illustrate a plurality of configurations of combustible cigarettes. Combustible cigarettes are tobacco products that include tobacco material that is aerosolized by burning the tobacco material to generate smoke. FIG. 3 is a combustible cigarette with a tobacco material 14 (e.g., a tobacco column) at the far right and a filter product in the form of a rod filter 10 positioned to the left of (and adjacent to) the tobacco material 14. As such, the rod filter 10 may be at the mouth end of the cigarette so that a user may place the rod filter 10 in the user’s mouth to draw tobacco smoke through the tobacco product. FIG. 4 is a combustible cigarette with a tobacco material 14 at the far right, and a filter product comprising a supplemental product 16 positioned to the left of (and adjacent to) the tobacco material 14 and a rod filter 10 positioned to the left of (and adjacent to) the supplemental product 16. The supplemental product 16, as such term is referred to herein, may comprise a variety of materials that may be supplementally used within tobacco products, such as activated charcoal filters, flavor agents/capsules, colored filters, etc. FIG. 5 is a combustible cigarette with a tobacco material 14 at the far right, and a filter product comprising a supplemental product 16 positioned to the left of (and adjacent to) the tobacco material 14, an empty space 18 (e.g., a hollow section) positioned to the left of (and adjacent to) the supplemental product 16, and a rod filter 10 positioned to the left of (and adjacent to) the empty space 16. FIG. 6 is a combustible cigarette with a tobacco material 14 at the far right, and a filter product comprising a rod filter 10 positioned to the left of (and adjacent to) the tobacco material 14 and a hollow tube 12 positioned to the left of (and adjacent to) the rod filter 10. As such, the hollow tube 12 may be at the mouth end of the cigarette so that a user may place the hollow tube 12 in the user’s mouth to draw tobacco smoke through the tobacco product. Finally, FIG. 7 is a combustible cigarette with a tobacco material 14 at the far right, and a filter product comprising a supplemental product 16 positioned to the left of (and adjacent to) the tobacco material 14, a rod filter 10 positioned to the left of (and adjacent to) the supplemental product 16, and a hollow tube 12 positioned to the left of (and adjacent to) the rod filter 10.

[059] Furthermore, FIGS. 8-12 illustrate a plurality of configurations of heat-not-burn sticks. Heat-not-burn sticks are tobacco products that include tobacco material that is vaporized by heating the tobacco material with an electronic heating element to generate vapor. FIG. 8 is a heat-not-burn stick with a tobacco material 14 (e.g., a tobacco column) at the far right, and a filter product comprising an empty space 18 (e.g., a hollow section) positioned to the left of (and adjacent to) the tobacco material 14 and a rod filter 10 positioned to the left of (and adjacent to) the empty space 18. As such, the rod filter 10 may be at the mouth end of the heat-not-burn stick so that a user may place the rod filter 10 in the user’s mouth to draw tobacco smoke through the tobacco product. FIG. 9 is a heat-not-burn stick with a tobacco material 14 (e.g., a tobacco column) at the far right, and a filter product comprising a supplemental filter 20 (e.g., a polylactic filter) positioned to the left of (and adjacent to) the tobacco material 14, an empty space 18 (e.g., a hollow section) positioned to the left of (and adjacent to) the supplemental filter 20, and a rod filter 10 positioned to the left of (and adjacent to) the empty space 18. FIG. 10 is a heat- not-burn stick with a tobacco material 14 (e.g., a tobacco column) at the far right, and a filter product comprising a hollow tube 12 positioned to the left of (and adjacent to) the tobacco material 14, a supplemental filter 20 (e.g., a polylactic filter) positioned to the left of (and adjacent to) the hollow tube 12, and a rod filter 10 positioned to the left of (and adjacent to) the secondary filter 20. FIG. 11 is a heat-not-burn stick with a tobacco material 14 (e.g., a tobacco column) at the far right, and a filter product comprising a first hollow tube 12 positioned to the left of (and adjacent to) the tobacco material 14, a supplemental product 16 positioned to the left of (and adjacent to) the first hollow tube 12, a supplemental filter 20 (e.g., a polylactic filter) positioned to the left of (and adjacent to) the supplemental product 16, and a second hollow tube 12 positioned to the left of (and adjacent to) the secondary filter 20. As such, the second hollow tube 12 may be at the mouth end of the heat-not-burn stick so that a user may place the second hollow tube 12 in the user’s mouth to draw tobacco smoke through the tobacco product. Finally, FIG. 12 is a heat- not-burn stick with a tobacco material 14 (e.g., a tobacco column) at the far right, and a filter product comprising a first hollow tube 12 positioned to the left of (and adjacent to) the tobacco material 14, a second hollow tube 12 positioned to the left of (and adjacent to) the first hollow tube 12, and a rod filter 10 positioned to the left of (and adjacent to) the second hollow tube 12. Notably, the first and second hollow tubes 12 of the heat-not-burn stick illustrated in FIG. 12 may have similar (or the same) external circumferences Cext but may have different internal diameters dint and/or wall thicknesses T_waii.

[060] Various configurations of filters products are shown and described above (and in the figures). However, it should be understood that embodiments of the present invention contemplate the use of even further configurations of rod filters and hollow tubes 10, 12 (as well as other materials) used with various types of consumer products, such as tobacco products. As such, the term tobacco product, as used herein, is not restricted to those explicitly described or shown in the figures.

[061 ] The rod filters and hollow tubes 10, 12 of embodiments of the present invention may be formed from fibers or filaments of polymeric material. A “fiber” can be either a filament or a staple. While reference may be made to “filaments” herein, every mention of filaments in an article can also be replaced with and provides support for “fiber” or “staple,” since fibers are filaments and staple fibers are cut from filaments. Thus, articles discussed herein can contain either single filaments fibers or staple fibers or both.

[062] The polymeric material used for the fibers is not particularly limiting. The fibers can be selected from, for example, cellulose esters, native celluloses, regenerated celluloses, and synthetic polymers. Non-limiting examples of the cellulose esters include organic acid esters such as cellulose acetates (e.g., cellulose diacetate and cellulose triacetate), cellulose butyrates, and cellulose propionates; inorganic acid esters such as cellulose nitrates, cellulose sulfates, and cellulose phosphates; mixed acid esters such as cellulose acetate propionates, cellulose acetate butyrates, cellulose acetate phthalates, and cellulose nitrates acetates; and cellulose ester derivatives such as polycaprolactone-grafted cellulose acetates. Non-limiting examples of the native celluloses include native celluloses derived from (prepared from) wood filaments such as pulps of wood such as softwood and hardwood; seed hair filaments such as linters and other raw cotton, Bombax cotton, and kapok; bast filaments typically of hemp, flax, jute, ramie, paper mulberry, and paper bush; and leaf filaments typically of Manila hemp (abaca) and New Zealand flax. Examples of the regenerated celluloses include, but are not limited to, viscose rayon, Cuprammonium rayon, Fortisan, and nitrate rayon. Non-limiting examples of the synthetic polymers include polyolefins such as polyethylene and polypropylene; poly(vinyl alcohol)s; polyesters such as polyethylene terephthalate)s; and polyamides. Each of different materials may be used alone or in combination. Desirably, the filaments are to be selected from, acrylic, modacrylic, aramid, nylon, polyester, polypropylene, rayon, polyacrylonitrile, polyethylene, PTFE, or cellulose acetate. In one aspect, the filaments comprise cellulose acetates, which include cellulose acetate, cellulose triacetates, cellulose propionates, cellulose butyrate, cellulose acetate-propionates, cellulose acetate-buty rates, cellulose propionatebutyrate, and cellulose acetate-phthalates. Other polymer which can be employed include starch acetates, acrylonitrile, vinyl chlorides, vinyl esters, vinyl ethers, any derivative thereof, any copolymer thereof, and any combination thereof. Fibers from such polymeric material may be produced by conventional techniques such as solution spinning, melt spinning and melt blowing.

[063] A particularly preferred embodiment of the present invention includes the rod filters and hollow tubes 10, 12 comprising cellulose ester fibers of cellulose acetate. One aspect of the present invention includes the rod filters and hollow tubes 10, 12 formed from cellulose ester fibers, each having a substantially C-shape cross-sectional shape. Such fibers may be prepared using a dry or wet-spinning process, such as by extruding a cellulose ester solution through a spinneret. Referring to FIG. 13, a fiber 30 is shown having a cross-sectional configuration of a closed “C” shape that is prepared by extruding a cellulose acetate dope or solution through an orifice of the spinneret. As used throughout, a fiber or filament exhibiting a closed C-shape has a cross-section in the shape of a “C” having a first proximal end 35 and a second proximal end 40 and having a hollow core 50. In more detail, a fiber or filament with a “closed C shape” means a fiber or filament that has a cross section in the shape of a “C” having a first proximal end and a second proximal end and that satisfies at least one condition A(i) or A(ii) and at least one condition B(i) or B(ii):

A. At least a portion of a first proximal end is either: i. oriented toward at least a portion of a second proximal end, or ii. contacting a portion of the second proximal end; and

B. The first and second proximal ends form either: i. a channel defined by a gap or separation between the first proximal end and the second proximal end of the “C” shape and having a transverse distance D1 , wherein the channel leads from an outer surface of the filament to a hollow core, wherein the hollow core is defined by an inner filament surface and having a diameter D2, and wherein D2/D1 > 1 , or ii. no channel resulting from at least a portion the first proximal end contacting at least a portion of the opposing second proximal end.

[064] As illustrated in FIG. 13, the fiber 30 is in the shape of a “C” having a first proximal end 35 and a second proximal end 40 and satisfies at least one condition A(i) or A(ii) and at least one condition B(i) or B(ii):

A. at least a portion of a first proximal end 35 is either: i. oriented toward at least a portion of the second proximal end 40, or ii. contacting a portion of the second proximal end 40, and as shown, there is no contact; and

B the first and second proximal ends 35 and 40 form either: i. a channel defined by a gap or separation between the first proximal end 35 and the second proximal end 40 of the “C” shape and having a transverse distance D1 , wherein the channel leads from an outer surface 55a of the fiber 30 to a hollow core 50, wherein the hollow core 50 is defined by an inner fiber surface 55b and having a diameter D2, and wherein D2/D1 > 1 , or ii. no channel or passageway resulting from at least a portion the first proximal end 35 contacting at least a portion of the opposing second proximal end 40, and as shown, the proximal ends in this case do not contact each other.

[065] In one embodiment or in combination with any of the mentioned embodiments, the channel opens into an annulus that has a diameter D2 that is greater than the smallest channel diameter D1. The distance D1 of the channel is taken as the smallest distance within the channel defined by the gap between the first proximal end 35 and the second proximal end 40 of the C shaped fiber 30, and the diameter D2 is taken as the largest diameter within the hollow core 50. The ratio of D2/D1 in the same units is greater than 1 :1 , or at least 1.1 :1 , or at least 1.2:1 , or at least 1 .3:1 , or at least 1.4:1 , or at least 1 .5:1 , or at least 1 .6:1 , or at least 1 .7:1 , or at least 1 .8:1 , or at least 1 .9:1 , or at least 2:1 , or at least 2.1 :1 , or at least 2.3:1 , or at least 2.5:1 , or at least 2.8:1 , or at least 3:1 , or at least 3.5:1 , or at least 4:1 or at least 4.5:1 or at least 5:1 or at least 5.5:1 , or at least 6:1 .

[066] Referring to FIG. 13A, the delineation and definition of a proximal end of the C-cross section shape is more particularly defined. The fiber 60 includes the outer periphery 55a forming an outer arc and the inner periphery 55b forming an inner arc circumscribing and forming the hollow core 50. The C shaped filament has proximal ends 35 and 40 having imaginary planes “x” and “y,” respectively, extending along the proximal ends 35 and 40. In determining if the filament 30 is a closed C as defined herein the orientation of the proximal ends 35 and 40 is determined. Accordingly, and with continued reference to FIG. 13A, the orientation of end 35 is the direction of an imaginary line (e.g., line 35a or 35b) extending away from and perpendicular to the portion of the plane x extending along the proximal end 35. Similarly, the orientation of end 40 is the direction of an imaginary line (e.g., line 40a or 40b) extending away from and is perpendicular to the plane y of proximal end 70. [067] Lines 35a or 35b can be drawn anywhere along and perpendicular to the portion of the plane x extending along the proximal end 35, and even though some lines may not intersect the portion of the opposing plane y extending along the proximal end 40, if any line perpendicular to the portion of the plane x extending along the proximal end 35 intersects the portion of the opposing plane y extending along the proximal end 40, the fiber 60 is a closed C shape. Likewise, lines 40a or 40b can be drawn anywhere along and perpendicular to the portion of the plane y extending along the proximal end 40, and even though some lines may not intersect the portion of the opposing plane x extending along the proximal end 35, if any line perpendicular to the portion of the plane y extending along the proximal end 40 intersects the portion of the opposing plane x extending along the proximal end 35, the fiber 60 is a closed C shape. As illustrated, this configuration of FIG. 13A would be a closed C shaped fiber 60 since the orientation of proximal end 35 is toward the proximal end 40 as shown by imaginary orientation line 35a intersecting the plane y of proximal end 40 even though imaginary line 35b does not. Likewise, this configuration of FIG. 13A would be a closed C shaped filament since the orientation of proximal end 40 is toward the proximal end 35 as shown by imaginary orientation line 40a intersecting the plane x of proximal end 35 even though imaginary line 40b does not. Either one of these conditions would satisfy the requirement that at least one of the proximal ends is oriented toward the other.

[068] The first proximal end 35 and second end 40 can be spaced apart a distance of less than 1 .0 radian, or less than 0.8 radian, or less than 0.5 radian, or less than 0.3 radian, or less than 0.1 radian and still be characterized as a closed C configuration, and in each instance not be touching, or be spaced apart by at least 0.01 radian, or at least 0.05 radian. In addition to the closed C shaped configurations discussed above in FIGS. 13 and 13A it should be understood that a fiber is considered to have a closed C shape when one of the proximal ends (e.g., end 35 or end 40) is contacting a portion of the other proximal end (e.g., the other of end 35 or end 40). [069] Conversely, FIG. 13B illustrates a fiber 70 that is not considered to be a closed C shape. In Figure 2B the orientation of proximal end 35 is not toward proximal end 40 because no imaginary line perpendicular to and along the plane x of proximal end 35, whether as illustrated by line 35a or 35b, can intersect proximal end 40 along the plane y. Similarly, proximal end 40 is not oriented toward proximal end 35 as shown by imaginary orientation lines 40a and 40b not intersecting proximal end 35 along its plane x.

[070] Referring again to FIG. 13, the core 50 of fiber 30 is hollow, providing the fiber 30 with a hollow cross-section. The term "hollow core" as used herein is not limited to a perfect circle or one in which the circumference is completely closed. In particular, a fiber includes a “hollow core” when the fiber comprises an outer periphery (e.g., periphery 55a) and an inner periphery (e.g., periphery 55b), with the inner periphery at least partially enclosing an empty interior space. For example, a hollow core can be oval, square, triangular, or other regular or irregular/distorted shape. Furthermore, the proximate ends 35 and 40 can be touching or in contact or can be separated from each other. In some embodiments, or in combination with any other mentioned embodiments, the hollow core 50 may have a diameter in its largest dimension that is larger than the largest distance between the proximal ends 35 and 40.

[071 ] The following description provides a process for making fibers (e.g., closed C fibers) that can be used in the rod filters and/or hollow tubes 10, 12. A spinning dope containing cellulose acetate and a solvent can be prepared and dry-spun under conditions known to those skilled in the art. The spinning solution temperature may be elevated and maintained by passing it through a heated candle filter. Generally, the candle filter temperature is not, under the given process conditions, above the boiling point of the solvent used in the spinning solution, such as acetone.

[072] At the spinneret, the solvent dope can be extruded through a plurality of holes to form continuous cellulose acetate fibers. The fibers may be gathered together to form bundles of several hundred, or even thousand, individual fibers. Each of these bundles, or bands, may include at least 100, 150, 200, 250, 300, 350, or 400 and/or not more than 1000, 900, 850, 800, 750, or 700 fibers. The spinnerets may be operated at any speed suitable to produce fibers and bundles having desired size and shape.

[073] The spinning dope composition contains cellulose acetate and a solvent in suitable amounts. The terms, "cellulose acetate tow", "acetate tow", or "acetate tow band" as used herein, refers to a continuous, crimped filament band comprising of cellulose acetate fibers. The term "cellulose acetate", as used herein, refers to an acetate ester of cellulose wherein the hydrogen in the hydroxyl groups of the cellulose glucose unit is replaced by acetyl groups through an acetylation reaction. The cellulose acetate can have a degree of substitution ranging from 2.2 to less than 3. As used herein, the term “degree of substitution” or “DS” refers to the average number of acyl substituents per an hydroglucose ring of the cellulose polymer, wherein the maximum degree of substitution is 3.0. In some embodiments, suitable cellulose acetates may have a degree of substitution less than 3 acetyl groups per glucose unit, preferably an average in the range of 2.2 to 2.8, or in the range of 2.4 to 2.7. In some cases, at least 90, 91 , 92, 93, 94, 95, 96, 97, 98, or 99 percent of the cellulose acetate has a DS of greater than 2.2, or 2.25. In some cases, at least 90 percent of the cellulose acetate can have a DS of greater than 2.2, 2.25, 2.3, or 2.35. Typically, acetyl groups can make up at least 1 , 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, or 60 percent and/or not more than 99, 95, 90, 85, 80, 75, or 70 percent of the total acyl substituents.

[074] The amount of cellulose acetate in the spinning dope composition can be from 22 wt.% to 32 wt.%, or more than 22 wt.% to 32 wt.%, or more than 24 wt.% to 32 wt.%, or from 26 to 30 wt.% and from 28 to 30 wt.%, based on the total weight of the dope solution. The amount of solvent present in the dope composition is from 65 wt.% to 78 wt.%, and desirably from 68 wt.% to 71 wt.%, based on the total weight of the dope solution. The inherent viscosity of the cellulose acetate in the spinning solution can be from 1 .35 to 1 .60. or from 1 .45 to 1.58.

[075] The solids content (i.e., solids added) of the spinning solution is generally between 22 and 32 wt.%. At the higher solids content, there is less amount of solvent that needs to be recovered, but at much above 32 weight percent, the spinning solution viscosity can be too high for good extrusion through the small spinneret holes. At a solids content from 22 weight percent or less, the flow rate of the dope solution through the spinneret is difficult to control, an excess of solvent has to be evaporated from the fibers and a consistent fiber shape is difficult to control, and the amount of acetone recovery is high. Additionally, spinning solutions containing low solids when spun into fibers tend to cause the fibers to stick to the outside surface of the metal face of the spinnerets and are, therefore, difficult to pull the filaments into a bundle or tow band.

[076] The spinning dope solution may also contain minor amounts of a delusterant such as TiO2, and minor amount of water, and minor amounts of a plasticizer. The dope solution according to the present invention generally has minor amounts of titanium dioxide added and minor amounts of water. The amount of TiO2 in the total spinning solution is generally below 1 wt.%, or not more than 0.5 wt.%, or not more than 0.3 wt.%, or no added TiO2. A minor amount of TiO2 can be added to increase the whiteness of the resulting filter. Excessively high amounts of TiO2 can plug the fine spinneret holes.

[077] If present, the amounts of delusterant, plasticizer, and water can each be 5 wt.% or less, or not more than 5 wt.% cumulatively. In one embodiment, aside from water, delusterant, cellulose acetate, and plasticizer, the remainder of the spinning dope solution is solvent, such as acetone. In one embodiment or in combination with any of the mentioned embodiments, the amount of acetone is at least 60 wt.%, or at least 70 wt.%, or at least 80 wt.%, or at least 90 wt.%, or at least 95 wt.%, or at least 98 wt.%, or 100 wt.%, based on the weight of all solvents other than water. Other solvents having an evaporation rate profile different than acetone will affect the shape of the fibers under the process conditions mentioned, and therefore, their amount should be minimized.

[078] In one embodiment or in combination with any of the mentioned embodiments, the spinning dope solution contains not more than 4.5 wt.%, or not more than 4 wt.%, or not more than 3 wt.%, or not more than 2 wt.%, or not more than 1 wt.%, or not more than 0.5 wt.% plasticizer based on the total weight of the cellulose acetate and plasticizer in the dope, or based on the weight spinning dope solution, or based on the total weight of the cellulose acetate and plasticizer in the fiber, or based on the weight of the fiber, or no plasticizer is added to the solution, or no plasticizer is present in the solution. If a plasticizer is employed, the plasticizer can be a compound as opposed to a polymer, and can have a molecular weight of not more than 400 g/mole, or not more than 300 g/mole, or not more than 250 g/mole. The fiber, upon exit from the spinneret, may also contain the same percentages of plasticizer, or lack of plasticizer, and any process for making the fibers can include dry spinning without plasticizer added to the dope solution or, if added, is within the limits described.

[079] The amount of water present in the spinning solution of the present invention is generally less than 5 wt.%, or not more than 3 wt.%, or not more than 1 to 2 wt.%, based on the weight of the dope solution or the fibers. Amounts of water much above 3 wt.% tend to slow the drying time of the resulting fibers whereas amounts of water much below about 1 wt.% are difficult to obtain since the acetone is recycled from water by distillation and ambient air is humid.

[080] In certain embodiments, the fibers used in the rod and/or hollow tubes 10, 12 may be spun through “D” shaped spinneret holes. Such fibers may be extruded in a generally longitudinally aligned manner and ultimately formed into filaments, or staple fibers, of any suitable size. For example, each fiber (filament or staple) may have a linear dpf (weight in g of 9000 m filament length, dpf) of at least any of at least 0.5, or more than 0.5, or at least 0.8 1 , 1 .5, 2, 2.5, 3, 4, or 5 dpf. In addition, or in the alternative, the dpf is not more than any of: 200, 100, 75, 50, 35, 30, 25, 20, 15, 14, 13, 12, 11 , 10, 9, 8, 7, 6, 5, 4.5, 4, 3.5 3, or 2.75 dpf. Examples of suitable dpf ranges include from 0.8 to 30, 1 .8 to 20, or from 1 to 25, or from 1 .5 to 20, or from 1 .5 to 15, or from 1 to less than 4, or from 4 to 30. In some particular embodiments, the fibers used in rod filters 10 may have a dpf from 1 .8 to 20. For example, fibers of rod filters 10 used with combustible cigarettes may have a dpf from 1.8 and 8.0 dpf, whereas fibers of rod filters 10 used with heat-not-burn sticks may have a dpf from 8.0 to 20.0. The fibers of hollow tubes 12 (e.g., for heat-not-burn sticks) may have a dpf from 3.4 to 8.0.

[081 ] The fibers, including filaments and staple fibers, are desirably monofilaments. In one embodiment, the fibers comprise at least 80 wt.%, or at least 90 wt.%, or at least 95 wt.%, or at least 97 wt.%, or 100 wt.% cellulose acetate polymer based on the weight of all polymers in the fiber, excluding plasticizers. In one embodiment, the fibers are not bicomponent fibers and are not the result of processing bicomponent fibers. The size of the individual filaments is not particularly limiting. The size can be given in terms of effective diameter, and in one aspect, the effective diameter of the filaments and staple fibers can range, for example, from 0.1 pm to 1000 pm, 1 pm to 500 pm, 1 pm to 100 pm, 1 pm to 30 pm, 10 pm to 1000 pm, 10 pm to 500 pm, 10 pm to 100 pm, 10 pm to 30 pm.

[082] The fibers can be formed into bundles or tow bands, each of which are multiple filaments placed adjacent to each other along their lengths such that the filaments remain untwisted or entangled, or into yarns which can be multiple filaments placed adjacent to each other along their lengths such that the filaments are twisted or entangled. Tow bands of fiber are often formed to allow for effective crimping of the filaments and can be cut into a staple fiber or processed as a continuous band, depending on the end use. As used herein, the term “staple fiber” refers to a filament cut from a filament yarn or tow band that has a discrete length, which is typically less than 150 mm, or less than 120 mm, or up to 100 mm, or up to 80 mm, or up to 65 mm, or up to 60 mm, or up to 55 mm. In some embodiments, the staple fibers may be cut to a length of at least: 1 , 1 .5, 2, 3, 4, 5, 6, 8, 10, 12, 15, 17, 20, 22, 25, 27, 30, 32, or 35 mm and up to 130 mm, or up to 120 mm, or up to 100mm, or up to 80 mm, or up to 65mm. Any suitable type of cutting device may be used that is capable of cutting the filaments to a desired length without excessively damaging the fibers. Examples of cutting devices can include, but are not limited to, rotary cutters, guillotines, stretch breaking devices, reciprocating blades, and combinations thereof. Once cut, the staple fibers may be baled or otherwise bagged or packaged for subsequent transportation, storage, and/or use. The cut length of the staple fibers may be measured according to ASTM D-5103.

[083] Fiber bands (i.e., tow bands) can be gathered having from 5 to 500,000 individual fibers in accordance with the present invention. Alternatively, the tow bands can have from 10 to 50,000; 10 to 40,000; 10 to 30,000; 10 to 20,000; 10 to 10,000; 10 to 1000; 100 to 50,000; 100 to 40,000; 100 to 30,000; 100 to 20,000; 100 to 10,000; 100 to 1000; 200 to 50,000; 200 to 40,000; 200 to 30,000; 200 to 20,000; 200 to 10,000; 200 to 1000; 1000 to 50,000; 1000 to 40,000; 1000 to 30,000; 1000 to 20,000; 1000 to 10,000; 5000 to 50,000; 5000 to 40,000; 5000 to 30,000; 5000 to 20,000; 5000 to 10,000; 10,000 to 50,000; 10,000 to 40,000; 10,000 to 30,000; or 10,000 to 20,000 fibers of the present invention. Nevertheless, the tow bands may have a total denier from 1 ,000 to 500,000, from 2,000 to 250,000, from 5,000 to 100,000, from 10,000 to 75,000, from 15,000 to 50,000, from 20,000 to 40,000, and/or from 25,000 to 30,000. In certain embodiments, the filter tow weight, i.e., the weight of the filaments only, is greater than 1 .7 mg/mm, or greater than 2.0 mg/mm, or 2.2 to 2.5 mg/mm.

[084] The fibers, formed into a tow band, can then be passed through a crimping zone where a patterned wavelike shape is imparted to at least a portion, or substantially all, of the individual fibers of the tow. The crimping zone may include at least one crimping device for mechanically crimping the fiber. After crimping, the tow band may be dried in a drying zone in order to reduce the moisture and/or solvent content of the fibers of the tow band. Thereafter, the fibers, in the form of a tow band, can be fed into and compressed by a baler into a bale of tow fibers.

[085] The rod filters and hollow tubes 10, 12 may be formed from the tow band using a conventional automated cigarette rod making machine. Exemplary cigarette rod making machines are of the type commercially available from Molins PLC or Hauni-Werke Korber & Co. KG. For example, cigarette rod making machines of the type known as MkX (commercially available from Molins PLC) or PROTOS (commercially available from Hauni- Werke Korber & Co. KG) can be employed. In more detail, rod filters 10 may be formed by drawing the tow band from the bale and passing the tow band through a blooming device. Specifically, compressed air can be jetted onto the tow band while a tensile strength is applied to the tow band, so as to “bloom” the tow band to adjust the width of the tow band as necessary.

[086] After the tow band has been sufficiently bloomed, a plasticizer such as triacetin may sprayed onto tow band. Thereafter, the tow band can be compressed and formed into the cylindrical shape of rod filters 10 inside a cylindrical feeding jet device. In some instances, wrapping paper may be wound around the outer periphery of the cylindrical tow band. Next, the cylindrical tow band (perhaps including the wrapping paper) can be cut by into individual rod filters 10. In this manner, a plurality of rod filter 10 can be manufactured. Hollow tubes 12 may be formed in essentially the same manner as the rod filters 12 described above; however, a mandrel may be included within the cylindrical feeding jet device. As such, when the tow band is fed and compressed within the feeding jet device, the tow band is formed around the mandrel so as to form the hollow tube shape.

[087] If desired, "non-wrapped" filters may also be produced. Such segments are produced using the types of techniques generally set forth herein. However, rather than employing a wrapping paper that circumscribes the longitudinally extending periphery of the filter material, a somewhat rigid rod may be provided, for example, by applying steam to the shaped mixed fibrous bundle. Techniques for commercially manufacturing non-wrapped filter rods are possessed by Essentra PLC, Milton Keys, UK.

[088] Filters utilizing the fibers described herein (e.g., closed C shaped fibers) may contain one or more particulate additive(s) which are not particularly limited and are those additives normally used in filters for smoking articles. The additives can be in powder (particle diameter of 50 to 150 pm) or granular form (particle diameter of 150 to 1000 pm). Examples of suitable particulate additives include flavorants or sorbents, e.g., a menthol solution, activated carbon/charcoal, zeolite, ion exchange resin, magnesium silicate like sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins and diatomaceous earths, or combinations thereof. Also, other additives, such as humectants, or coloring agents, can be used. According to certain aspects, the particulate additive comprises or is charcoal/activated carbon.

[089] In view of the above, embodiments of the present invention include improved filter products for tobacco products. Such filter products, e.g., the rod filters and hollow tubes 10, 12, may provide for improved capabilities, such as enhanced hardness, reduced friction, and reduced pressure drops. In more detail, embodiments of the present invention may include a filter product for use in a tobacco product. Such a filter product may be a rod filter 10 or a hollow tube 12, as previously described. Specifically, the filter product may comprise a plurality of fibers. In some embodiments, the fibers may be cellulose acetate fibers. Such fibers may include hollow core sections. In some embodiments, the fibers may have closed C shaped cross sections.

[090] Embodiments may provide for such above-described filter products (e.g., rod filters and/or hollow tubes 10, 12) to be included with various types of tobacco products, such as combustible cigarettes and heat-not-burn sticks. Specifically, embodiments may comprise a tobacco product (e.g., combustible cigarette and/or heat-not-burn stick) that includes tobacco and a filter product, with the filter product comprising a plurality of cellulose acetate fibers having hollow core sections. In some embodiments, the fibers may comprise fibers having closed C shaped cross sections.

[091 ] To provide enhanced hardness, the individual fibers included in the filter products may have an improved moment of inertia values over fibers of previously-made filter products. Such improved moment of inertia values may be obtained by the fibers having hollow cross sections, such as the case with the fibers having closed C cross-section shapes. In more detail, moment of inertia for a fiber reflects how the area of a cross section of the fiber is distributed relative to a particular axis. The more of the fiber’s mass that is separated from the axis, the greater the moment of inertia. A greater moment of inertia will correspond with a greater resistance of the cross section to bending. Stated differently, the greater the moment of inertia for a given fiber, the rigidity of the fiber increases. Fibers with hollow cross sections, such as closed C fibers, locate much of their compositional material away from their longitudinal axis (e.g., the fiber’s bending axis), and therefore can provide a significant increase in moment of inertia, and therefore bending stiffness or rigidity, when compared with solid cross section fibers (such as those having Y or circular shaped cross sections).

[092] In view of the above, embodiments of the present invention provide for the fibers within the inventive filter products to include, on average, an area moment of inertia of at least 50,000 pm⁴, at least 60,000 pm⁴, at least 70,000 pm⁴, at least 75,000 pm⁴, at least 80,000 pm⁴, at least 90,000 pm⁴, 100,000 pm⁴, at least 110,000 pm⁴, at least 120,000 pm⁴, at least 130,000 pm4, or at least 135,000 pm4, or at least 140,000 pm⁴, and/or from 50,000 pm⁴ to 140,000 pm⁴, from 60,000 pm⁴ to 140,000 pm⁴, from 70,000 pm⁴ to 140,000 pm⁴, from 80,000 pm⁴ to 140,000 pm⁴, from 90,000 pm⁴ to 140,000 pm⁴, from 100,000 pm⁴ to 140,000 pm⁴, from 110,000 pm⁴ to 140,000 pm⁴, from 120,000 pm⁴ to 140,000 pm⁴, from 130,000 pm⁴ to 140,000 pm⁴, from 50,000 pm⁴ to 100,000 pm⁴, from 60,000 pm⁴ to 100,000 pm⁴, from 70,000 pm⁴ to 100,000 pm⁴, from 80,000 pm⁴ to 100,000 pm⁴, from 90,000 pm⁴ to 100,000 pm⁴, from 80,000 pm⁴ to 120,000 pm⁴, from 90,000 pm⁴ to 120,000 pm⁴, from 100,000 pm⁴ to 120,000 pm⁴, or from 110,000 pm⁴ to 120,000 pm⁴. In certain embodiments, one or more of the fibers within each of the inventive filter products may include a maximum area moment of inertia of at least 75,000 pm⁴, at least 80,000 pm⁴, at least 90,000 pm⁴, at least 100,000 pm⁴, at least 1 10,000 pm⁴, at least 120,000 pm⁴, at least 130,000 pm⁴, at least 135,000 pm⁴, at least 140,000 pm⁴, or at least 145,000 pm⁴.

[093] For a given fiber, an area moment of inertia value may be obtained by first determining the principal moments of inertia at the centroid of a cross-sectional area of the fiber (i.e., "lx” and “ly” as illustrated for the fiber 30 shown in FIG. 14). Next, the following equation may be applied: area moment of inertia = / x² + ly².

[094] To provide reduced friction, the fibers included in the filter products may have an improved coefficient of friction values over fibers of previously-made filter products. Such improved coefficient of friction values may be obtained by the fibers having generally round or circular exterior surfaces (e.g., outer surfaces 55b), such as the case with the fibers having closed C cross-section shapes. In more detail, the round or circular exterior surfaces provide reduced contact areas, particularly with respect to fibers with Y-shaped cross-sections, so as to reduce the friction between other fibers and/or other materials, such as metal components of the filter making machines (e.g., the mandrel). Regardless, embodiments provide for the fibers within the inventive filter products to include fiber-to-fiber coefficient of friction values of no more than 0.150, no more than 0.145, no more than 0.140, no more than 0.135, no more than 0.130, or no more than 0.129, or no more than 0.125, and/or from 0.125 to 0.150, from 0.130 to 0.145, from 0.130 to 0.140, or 0.130 to 0.135. Embodiments provide for the fibers within the inventive filter products to include fiber-to-metal coefficient of friction values of no more than 0.568, no more than 0.565, no more than 0.560, no more than 0.555, no more than 0.550, no more than 0.545, no more than 0.542, or no more than 0.540, and/or from 0.540 to 0.560, from 0.540 to 0.555, from 0.540 to 0.550, or 0.540 to 0.545.

[095] Given such reduced coefficient of friction values, it is understood that cellulose acetate tow made from filaments with closed C shaped cross sections can be processed at faster rates than tow from filaments of other cross-sectional shapes (e.g., filaments with round/circular and/or Y shaped cross sections). Specifically, it has been found that cellulose acetate tow formed from filaments with closed C shaped cross sections can be processed into filter products approximately 30% faster than cellulose acetate tow formed from filaments having Y shaped cross sections and approximately 13% faster than cellulose acetate tow formed from filaments having round/circular shaped cross sections.

[096] In some embodiments, the inventive filter products may comprise cylindrical rods, such as the rod filter 10, with such cylindrical rods having a generally solid cross section. The cylindrical rod filters are formed from a plurality of fibers (e.g., cellulose acetate fibers), with the fibers including hollow core sections. As such, the fibers may have closed C shaped cross-sections. Regardless, the cylindrical rod filter may have a mass of no more than 560 mg and a hardness of at least 83.0%. Such hardness values are determined using a Borgwaldt testing device with a 3 Kg mass, as discussed in more detail in the below Examples section. In certain embodiments, the cylindrical rod filter, with the mass of no more than 560 mg, may have a hardness of at least 82.8%, at least 82.9%, at least 83.1%, at least 83.2%, at least 83.3%, at least 83.4%, at least 83.5%, at least 83.6%, at least 83.7%, at least 83.8%, at least 83.9%, or at least 84.0%, and/or from 82.8 to 84.0%, from 82.9 to 83.8%, or from 83.0 to 83.6%. Furthermore, in some embodiments, the cylindrical rod filter may have a hardness value of at least 83.0% with the mass of the cellulose acetate in the rod filter being no more than 555 mg, no more than 550 mg, no more than 545 mg, no more than 540 mg, no more than 535 mg, no more than 530 mg, no more than 525 mg, or no more than 520 mg, and/or from 520 to 560 mg, from 530 to 560 mg, from 540 to 560 mg, and/or from 550 to 560 mg.

[097] In certain further embodiments, the cellulose acetate in the cylindrical rod filter of embodiments of the present invention may have a mass of no more than 540 mg while the rod filter has a hardness of at least 83.5%, at least 83.6%, at least 83.7%, at least 83.8%, at least 83.9%, or at least 84.0%, and/or from 83.5 to 84.0%, from 83.6 to 83.9%, or from 83.7 to 83.8%. In still further embodiments, the cylindrical cellulose acetate in the rod filter of embodiments of the present invention may have a mass of no more than 580 mg while the rod filter has a hardness of at least 84.5%, at least 84.6%, at least 84.7%, at least 84.8%, at least 84.9%, or at least 85.0%, and/or from 84.5 to 85.0%, from 84.6 to 84.9%, or from 84.7 to 84.8%.

[098] In some embodiments, the cylindrical rod filters may be regularsized filters having exterior diameters d_ext greater than 7.00 mm. In such embodiments, the regular-sized cylindrical rod filters may have hardness values from 81.0 and 84.0%. In other embodiments, the cylindrical rod filters may be slim-sized filters having exterior diameter dext from 6.00 and 7.00 mm. In such embodiments, the slim-sized cylindrical rod filters may have hardness values from 75.0 and 82.0%. In further embodiments, the cylindrical rod filters may be microslim-sized filters having exterior diameters dext from 5.40 and 5.99 mm. In such embodiments, the slim-sized cylindrical rod filters may have hardness values from 72.0 and 77.0%. [099] In some embodiments, the inventive filter products may comprise cylindrical rods, such as the rod filter 10, with such cylindrical rods having a generally solid cross section. The cylindrical rod filters are formed from a plurality of fibers (e.g., cellulose acetate fibers), with the fibers including hollow core sections. As such, the fibers may have closed C shaped cross-sections. Regardless, in some specific embodiments, the cylindrical rod filter may have cellulose acetate with a mass of from 520 and 600 mg. Furthermore, when such specific cylindrical rod filters are used in a tobacco product, such cylindrical rod filters may be configured to experience a pressure drop of no more than 1 15 mmWG. In certain embodiments, the cylindrical rod filter, having cellulose acetate with a mass of from 520 to 600 mg, may be configured to experience a pressure drop of no more than 1 10 mmWG or no more than 105 mmWG, and/or from 105 to 115 mmWG, from 105 to 110 mmWG, or from 110 to 1 15 mmWG. Furthermore, in some embodiments, the cylindrical rod filter may experience a pressure drop of no more than 115 mmWG with the mass of the cellulose acetate in the filter being from 530 to 590 mg, from 540 to 580 mg, from 550 to 570 mg, and/or about 560 mg.

[0100] In additional embodiments, the inventive filter products may comprise hollow cylindrical tubes, such as the hollow tube 12, with each of such tubes having an inner diameter and an outer diameter presenting a hollow cross section. The hollow tubes are formed from a plurality of fibers (e.g., cellulose acetate fibers), with the fibers including hollow core sections. As such, the fibers may have closed C shaped cross-sections. Regardless, the cylindrical hollow tubes may have a mass of no more than 495 mg and a hardness of at least 92.0%. Such hardness values are determined using a Borgwaldt testing device with a 3 Kg mass, as discussed in more detail in the below Examples section. In certain embodiments, the cylindrical hollow tube, with the mass of no more than 495 mg, may have a hardness of at least 92.1 %, at least 92.2%, at least 92.3%, at least 92.4%, or at least 92.5%, and/or from 92.0 to 92.5%, from 92.1 to 92.4%, or from 92.2 to 92.3%. Furthermore, in some embodiments, the cylindrical hollow tube may have a hardness value of at least 92.0% with the mass of the cellulose acetate in the hollow tube being no more than 492 mg, no more than 490 mg, no more than 487 mg, no more than 485 mg, no more than 483 mg, or no more than 481 mg, and/or from 481 to 495 mg, from 481 to 490 mg, from 481 to 487 mg, and/or from 481 to 485 mg. In some additional embodiments, the cylindrical hollow tubes may have a hardness value of at least 92.0%, at least 92.1%, at least 92.2%, at least 92.3%, at least 92.4%, or at least 92.5%with a mass of no more than 497 mg.

[0101] In some embodiments, the hollow tubes may have such abovedescribed hardness values at various sizes. For example, in some embodiments, the hollow tubes (having a mass of no more than 495 mg and a hardness of at least 92.0%) may have exterior diameters dext from 16 to 24 mm, from 18 to 22 mm, or about 20 mm. Furthermore, in some embodiments, the hollow tubes (having a mass of no more than 495 mg and a hardness of at least 92.0%) may have wall thicknesses T_waii (the distance from the respective exterior diameter d_ext to the interior diameter dint) from 0.6 to 1 .4 mm, from 0.8 to 1 .2 mm, or about 1 .0 mm.

Example 1

[0102] A plurality of cellulose acetate filaments were formed having a dpf of approximately 6.7. Such filaments were formed by extruding a cellulose acetate dope solution through orifices of a spinneret, as was previously described. The resulting filaments were formed into a crimped tow band comprising from ten to fifteen fibers. A first sample of cellulose acetate filaments, EX1 -C, was cast in epoxy resin under tension and sectioned/polished to expose the filament cross-sectional areas. The filaments in the EX1 -C sample had a closed C shaped cross section. A second sample of cellulose acetate filaments, EX1 -R, was cast in epoxy resin under tension and sectioned/polished to expose the filament cross-sectional areas. The filaments in the EX1 -R sample had a solid, round/circular shaped cross section.

[0103] To determine the moment of inertia of the filaments, the EX1 -C and EX1 -R samples were imaged at high contrast under a light microscope. The images were imported into Solidworks software to outline the cross- sectional shapes of the filaments. The software then calculated each filament cross-sectional area and principal moments of inertia (i.e., lx and ly) of each area at the centroid of filament. The resulting moment of inertia for the filaments were determined based on the algorithm previously described. It was determined that the filaments from the EX1 -C group, having the hollow, closed C shaped cross sections, had an average moment of inertia value of 74,297 pm⁴, with at least one of the filaments having a maximum moment of inertia value of 141 ,566 pm⁴. In contrast, the filaments from the EX1 -R group, having the sold, round/circular shaped cross sections, had an average moment of inertia value of 49,754 pm⁴, with at least one of the filaments having a maximum moment of inertia value of 74,323 pm⁴. Thus, the filaments having the closed C shaped cross sections had significantly higher moment of inertia values than the filaments having round/circular shaped cross sections. It is generally understood that moment of inertia values are indicative of the ability of a filament to resist bending or deflection. In particular, the higher the moment of inertia, the stiffer or more rigid the filament. As such, it was determined that the filaments having the closed C shaped cross sections were significantly more rigid (and less prone to bending) than the filaments having round/circular shaped cross sections. Such an increase in rigidity can be beneficial in the construction of filters to manufacture filters with preferred levels of hardness, as discussed more below.

Example 2

[0104] Ten bobbins of multifilament yarns were produced at zero twist level. In more detail, a first yarn of cellulose acetate filaments, EX2-C, was formed, with such filaments having a closed C shaped cross section. A second yarn of cellulose acetate filaments, EX2-R, was formed, with such filaments having a solid, round/circular shaped cross section. A third yarn of cellulose acetate filaments, EX2-Y, was formed, with such filaments having a solid Y shaped cross section. All of the yarns were formed with the same composition (i.e., cellulose acetate filament composition, lubricant content, denier, and entanglements). Yarn to yarn and yarn to metal pin coefficients of friction were measured in a Lawson-Hemphill CTTE friction testing device. Yarn-to-yarn measurements were made according to ASTM D3412, Standard Test Method for Coefficient of Friction, Yarn to Yarn, while Yarn-to-metal measurement were made according to ASTM D3108, Standard Test Method for Coefficient of Friction, Yarn to Solid Material.

[0105] It was found that the EX2-C yarns, formed from filaments having closed C shaped cross sections, had a fiber-to-metal coefficient of friction of 0.542 and a fiber-to-fiber coefficient of friction of 0.129. The EX2-R yarns, formed from filaments having solid, round/circular shaped cross sections, had a fiber-to-metal coefficient of friction of 0.419 and a fiber-to-fiber coefficient of friction of 0.136. The EX2-Y yarns, formed from filaments having solid, Y shaped cross sections, had a fiber-to-metal coefficient of friction of 0.569 and a fiber-to-fiber coefficient of friction of 0.152. Thus, it was shown that the EX2- C yarns had a lower (i) fiber-to-metal coefficient of friction value than that of the EX2-Y yarns, and (ii) fiber-to-fiber coefficient of friction values than that of both the EX2-R and EX2-Y yarns. Given such reduced coefficient of friction values, it is understood that cellulose acetate tow made from filaments with closed C shaped cross sections can be processed (e.g., to form filter products for tobacco products) at faster rates than tow from filaments of other cross- sectional shapes (e.g., filaments with round/circular and/or Y shaped cross sections).

Example 3

[0106] Three sets of thirty filters, EX3-C, EX3-R, and EX3-C, were formed using a Hauni KDF-AF4 filter making device. Each of the filters comprised a solid, cylindrically-shaped rod filter, such as rod filter 10 discussed above in the detailed description. The filters were formed from cellulose acetate tow having a total denier of approximately 26,800, with the filaments from the tow having a dpf of approximately 6.7. Each of the filters was formed with a length of 120 mm, a circumference of 24.4 mm, and a plugwrap thickness of 0.037 mm. The first set of filters, EX3-C, was formed from cellulose acetate tow comprising filaments having closed C shaped cross sections. The second set of filters, EX3-R, was formed from cellulose acetate tow comprising filaments having a solid, round/circular shaped cross sections. The third set of filters, EX3-Y, was formed from cellulose acetate tow comprising filaments having solid, Y shaped cross sections. The three sets of filters were tested using Coresta Standard method to determine pressure drop capability curves for the filters, with such capability curves comprising bivariate plots illustrating pressure drop values for given filter weights.

[0107] To obtain pressure drop capability curves, filters in each set were produced at the highest tow mass/weight possible (i.e., maximum capability) and the lowest mass/weight possible (minimum capability). The maximum capability point was defined as the point at which the garniture of the plug maker will not accept additional tow. Attempts to increase the tow mass/weight beyond this point would result in roll wraps, failure to seal the rod seam, or excessive variation in filter properties. The minimum capability point was defined as supplying the lowest tow mass/weight possible to the garniture while maintaining an acceptable filter from the standpoint of no wrinkles and very slight end recess (approximately 1.0 mm). Filters at midpoint mass/weights (halfway between minimum and maximum) were also produced. The filters produced at these three conditions (maximum, minimum, and midpoint mass/weights) were tested for pressure drop, as described above, and curves were plotted through the measured pressure drop values to generate pressure drop capability curves, which are plotted graphically in FIG. 15.

[0108] As illustrated, the filters comprised of closed C shaped filaments (i.e., EX3-C) showed significantly reduced pressure drops when compared with the filters comprised of either round/circular shaped filaments (i.e., EX3-R) or Y shaped filaments (i.e., EX3-Y). For instance, at the mass of 560 mg, the filters comprised of closed C shaped filaments (i.e., EX3-C) provided a pressure drop of 105 mmWG. In contrast, the filters comprised of Y shaped filaments (i.e., EX3-Y) provided a significantly higher pressure drop of 150 mmWG. It is noted that pressure drop values for the filters comprised of round/circular shaped filaments (i.e., EX3-R) were unable to made at such a low mass/weight of 560 mg. As such, it was shown that filters comprised of closed C shaped filaments (i.e., EX3-C) were able to achieve preferable lower pressure drop values across a range of mass/weights, as compared to filter comprised of differently shaped filaments, e.g., of Y shaped filaments (i.e. , EX3-Y) and round/circular shaped filaments (i.e., EX3-R).

[0109] In addition, groups of ten filter rods from each of the three sets of filters, EX3-C, EX3-R, and EX3-C, were tested using a Borgwaldt H37 testing device to determine hardness values for the filters. Specifically, a 3 Kg load was applied to each of the filters so as to compress the filters. Thereafter, the load was released. The original and final exterior diameters dext were measured, and the hardness value was determined for each filter as the ratio between the final and original exterior diameters dext- To obtain hardness capability curves for the filters, the hardness values were obtained for the three filter conditions (maximum, minimum, and midpoint mass/weights), as described above. Curves were plotted through the measured hardness values to generate hardness capability curves, which are plotted graphically in FIG. 16. Such capability curves comprising bivariate plots illustrating hardness values for given filter weights.

[0110] As illustrated, the filters comprised of closed C shaped filaments (i.e., EX3-C) showed an increase in hardness, over a significant portion of the filters’ mass ranges, when compared with the filters comprised of either round/circular shaped filaments (i.e., EX3-R) or Y shaped filaments (i.e., EX3- Y). For example, at the mass of 560 mg, the filters comprised of closed C shaped filaments (i.e., EX3-C) provided a hardness value of 84%. In contrast, the filters comprised of Y shaped filaments (i.e., EX3-Y) provided a significantly lower hardness value of 82.7 It is noted that hardness values for the filters comprised of round/circular shaped filaments (i.e., EX3-R) were unable to made at such a low mass/weight of 560 mg. As such, it was shown that filters comprised of closed C shaped filaments (i.e., EX3-C) were able to achieve acceptable hardness values using less tow than filters comprised of differently shaped filaments, e.g., of Y shaped filaments (i.e., EX3-Y) and round/circular shaped filaments (i.e., EX3-R).

Example 4

[011 1] Three sets of ten filter products, EX4-C, EX4-R, and EX4-C, were formed using a Hauni NWT KDF-2ER and NWT KDF-M filter making devices. Each of the filter products comprised a hollow, cylindrically-shaped hollow tube, such as hollow tube 12 discussed above in the detailed description. The hollow tubes were formed from cellulose acetate tow having a total denier of approximately 26,800, with the hollow tubes having a dpf of approximately 6.7. Each of the hollow tubes was formed with a length of 96.1 mm, an exterior diameter d_ext of 7.1 mm, a wall thickness T_wail of 1 ,05mm, and a triacetin content of 100 mg. The first set of hollow tubes, EX4-C, was formed from cellulose acetate tow comprising filaments having closed C shaped cross sections. The second set of hollow tubes, EX4-R, was formed from cellulose acetate tow comprising filaments having a solid, round/circular shaped cross sections. The third set of hollow tubes, EX4-Y, was formed from cellulose acetate tow comprising filaments having solid, Y shaped cross sections.

[0112] The three sets of filters products, EX4-C, EX4-R, and EX4-C, were tested using a Borgwaldt H37 testing device to determine hardness values for the hollow tubes. Specifically, a 3 Kg load was applied to each of the hollow tubes so as to compress the hollow tubes. Thereafter, the load was released. The original and final exterior diameters d_ext were measured, and the hardness value was determined for each hollow tube as the ratio between the final and original exterior diameters dext. To obtain hardness capability curves for the hollow tubes, the hardness values were obtained for the three filter conditions (maximum, minimum, and midpoint mass/weights) described above in Example 3. Curves were plotted through the measured hardness values to generate hardness capability curves, which are plotted graphically in FIG. 17. Such capability curves comprising bivariate plots illustrating hardness values for given hollow tube weights.

[0113] As illustrated, the hollow tubes comprised of closed C shaped filaments (i.e., EX4-C) showed an increase in hardness, over the entirety of the mass/weight range, when compared with the hollow tubes comprised of either round/circular shaped filaments (i.e., EX4-R) or Y shaped filaments (i.e., EX4- Y). For example, it is understood that a hardness value of 92% is generally considered a standard hardness value for hollow, cylindrically-shaped hollow tubes. The hollow tubes comprised of closed C shaped filaments (i.e., EX4-C) were shown to achieve such hardness value of 92% with only a mass of 481 mg. In contrast, the hollow tubes comprised of Y shaped filaments (i.e. , EX4- Y) were unable to achieve the hardness value of 92% until they reached a mass/weight of 497 mg. Similarly, the hollow tubes comprised of round/circular shaped filaments (i.e., EX4-R) were unable to achieve the hardness value of 92% until they reached a mass/weight of 520 mg. As such, it was shown that hollow tubes comprised of closed C shaped filaments (i.e., EX4-C) were able to achieve acceptable hardness values using less tow material than hollow tubes comprised of differently shaped filaments, e.g., of Y shaped filaments (i.e., EX4-Y) and round/circular shaped filaments (i.e., EX4-R).

[0114] While the invention has been disclosed in conjunction with a description of certain embodiments, including those that are currently believed to be the preferred embodiments, the detailed description is intended to be illustrative and should not be understood to limit the scope of the present disclosure. As would be understood by one of ordinary skill in the art, embodiments other than those described in detail herein are encompassed by the present invention. Modifications and variations of the described embodiments may be made without departing from the spirit and scope of the invention.

[0115] It will further be understood that any of the ranges, values, or characteristics given for any single component of the present disclosure can be used interchangeably with any ranges, values or characteristics given for any of the other components of the disclosure, where compatible, to form an embodiment having defined values for each of the components, as given herein throughout. For example, a polymer layer can be formed comprising plasticizer content in any of the ranges given in addition to any of the ranges given for residual hydroxyl content, where appropriate, to form many permutations that are within the scope of the present invention but that would be cumbersome to list.

Claims

WHAT IS CLAIMED IS:

1 . A filter product for use in a consumer product, said filter product comprising: a hollow tube formed from a plurality of cellulose acetate fibers, wherein the fibers include hollow core sections, wherein said hollow tube includes an inner diameter and an outer diameter, wherein the cellulose acetate within said hollow tube has a mass of no more than 495 mg, and said hollow tube has a hardness of at least 92.0% (Borgwaldt 3Kg).

2. The filter product of claim 1 , wherein the cellulose acetate has a degree of substitution (DS) from 2.2 to 2.8.

3. The filter product of any of claims 1 or 2, wherein said hollow tube is wrapped in paper.

4. The filter product of any of claims 1-3, wherein said fibers have a closed C shaped cross section, and wherein a fiber has a closed C shape cross section when the cross section presents a proximate first end and a proximate second end and satisfies at least one condition A(i) or A(ii) and at least one condition B(i) or B(ii):

5. The filter product of any of claims 1-4, wherein the consumer product is a tobacco product.

6. The filter product of any of claims 1 -5, wherein the tobacco product is a combustible cigarette.

7. The filter product of any of claims 1 -5, wherein the tobacco product is a heat-not-burn stick.

8. The filter product of claim 7, wherein the fibers each has a denier per filament (dpf) from 3.4 to 8.0.

9. The filter product of claim 7, wherein said filter product is formed from a tow of fibers, wherein the tow has a total denier from 20,000 to 40,000.

10. The filter product of any of claims 1-7, further comprising a plasticizer.

11 . The filter product of claim 10, wherein the plasticizer is triacetin.

12. The filter product of any of claims 1 -7, 10, or 11 , wherein the cellulose acetate within said hollow tube has a mass of no more than 492 mg, no more than 490 mg, no more than 487 mg, no more than 485 mg, no more than 483 mg, or no more than 481 mg.

13. The filter product of any of claims 1 -7 or 10-12, wherein said hollow tube has a hardness of at least at least 92.1%, at least 92.2%, at least 92.3%, at least 92.4%, or at least 92.5%.

14. The filter product of any of claims 1 -7 or 10-13, wherein said fibers have, on average, an area moment of inertia of at least 50,000 p m⁴, at least 60,000 pm⁴, at least 70,000 pm⁴, and/or at least 75,000 pm⁴.

15. The filter product of any of claims 1 -7 or 10-14, wherein said fibers have a fiber-to-metal coefficient of friction of no more than 0.565 or a fiber-to- fiber coefficient of friction of no more than 0.134.

16. The filter product of any of claims 1 -7 or 10-15, wherein said hollow tube has an external circumference C_ext from 12 to 28 mm, from 14 to 26 mm, from 16 to 24 mm, or from 18 to 22 mm.

17. The filter product of any of claims 1 -7 or 10-16, wherein said hollow tube includes a wall extending from an inner diameter dint to an external diameter dext, wherein said wall has a thickness W_t from 0.2 mm to 1.8 mm, from 0.4 mm to 1 .6 mm, from 0.6 mm to 1 .4 mm, and/or 0.8 mm to 1 .2 mm.

18. The filter product of any of claims 1 -4, wherein the consumer product is a botanical product.

19. The filter product of any of claim 18, wherein the botanical product is configured to generate vaporized plant-based substances.

20. A filter product for use in a consumer product, said filter product comprising: a hollow tube formed from a plurality of cellulose acetate fibers, wherein the fibers include hollow core sections, wherein said hollow tube includes an inner diameter and an outer diameter, wherein the cellulose acetate within said hollow tube has a mass of no more than 495 mg, and said hollow tube has a hardness of at least 92.2% (Borgwaldt 3Kg).