Cellulose acetate filaments having a cross-sectional shape with a specific surface area index

Abstract

Disclosed herein are cellulose acetate tow as well as tow bands, tow bales, and filters formed from the cellulose acetate tow. The tow comprises cellulose acetate tow with a DPF of greater than 7.0 to 12.5 and having filaments with a cross-sectional shape with a specific surface area (SSAi) of less than 2.00.

Description

PATENT Atorney Docket No.: 1544951 -62302 WO-CD Client Ref.: 2024P0007 / 2023P0157-WO-PCTCELLULOSE ACETATE FILAMENTS HAVING A CROSS- SECTIONAL SHAPE WITH A SPECIFIC SURFACE AREA INDEXPRIORITY CLAIM

[0001] This application claims benefit of U.S. Provisional Patent Application No.63 / 759,933, entitled, “CELLULOSE ACETATE FILAMENTS HAVING A CROSS-SECTIONAL SHAPE WITH A SPECIFIC SURFACE AREA INDEX”, filed February 18, 2025, the contents of which are hereby incorporated by reference in their entirety.FIELD OF THE INVENTION

[0002] The present invention generally relates to tow, tow bands, and filters comprising the tow, as well as to methods of manufacturing the same. In particular, the present invention relates to tow and methods of manufacturing tow meeting certain parameters, including a filament cross-sectional shape to meet a specific surface area index value.BACKGROUND OF THE INVENTION

[0003] Cellulose esters are widely used for many purposes, including as cellulose acetate tow in both traditional cigarette filters and aerosol generating device filters. Although cellulose esters such as cellulose acetate are biopolymers known to degrade, the rate of degradation is slower than natural cellulose. For example, cigarette filters may take up to 15 years to degrade because cellulose acetate does not degrade until sufficient acetyl groups have been removed, allowing for microorganisms to recognize the material for degradation. After smoking, the filters are often discarded in the environment and are one of the most common forms of man-made litter in the world. An estimated 4.5 trillion cigarette filters become litter each year. Due to the degradation time of cellulose acetate and to the plasticizer contained in the filter, the litter remains longer than desirable. Although attempts have been made to form biodegradable filters comprising cellulose acetate, these attempts have been unsuccessful for a variety of reasons, including an undesirable change to the taste of the cigarette due to modifications and / or additives and degradation time not being sufficiently reduced. Molded articles made of cellulose esters suffer from similar deficiencies.

[0004] US Pub. No. 2017 / 0006912 discloses a cellulose acetate tow band for use in a cigarette filter, in which a filament denier is not less than 5.0 denier, a Feret area of a filament is not less than 0.5, and / or a ratio S / L of a cross-sectional area S of the filament to a cross-sectional peripheral length L of the filament is not less than 5. The filament denier may be not more than 10 denier. The Feret area may be not more than 0.9. The ratio S / L may be not more than 9. In an apparatus for or a method of manufacturing a tow band, round-shaped spinning holes (10) each with a diameter of not less than 50 pm are used. The diameter of each roundshaped spinning hole (10) may be not more than 100 pm.

[0005] A need remains, however, for a cellulose acetate tow that, when formed into a filter, has an acceptable encapsulated pressure drop while not significantly otherwise affecting the production of the final product or affecting its performance.SUMMARY OF THE INVENTION

[0006] In some embodiments, the present disclosure is directed to a cellulose acetate tow comprising cellulose acetate filaments, the tow having: a degree of substitution from 2.0 to 2.9; a denier per filament (dpf) from greater than 7.0 to 12.5; a total denier from 10,000 to 100,000; and wherein the cellulose acetate filaments have a cross-sectional shape with a specific surface area index (SSAi) of less than 2.00, where SSAi = measured perimeter (p) / perimeter of circle of equivalent area (p); and further wherein the cross-sectional shape is not Y-shaped. In some aspects, the DPF is from 8.0 to 12.5, from 9.0 to 12.5, or from 9.0 to 12.0. In some aspects, the total denier is from 15,000 to 100,000, from 15,000 to 80,000, from 20,000 to 60,000, or from 25,000 to 40,000. In some aspects, the cross-sectional shape is polygonal. In some aspects, the cross-sectional shape is a C-shaped. The cellulose acetate may have a degree of substitution from 2.3 to 2.7. In some aspects, the SSAi is from 1.00 to 2.00, from 1.20 to 1.90, or from 1.25 to 1.80. In some aspects, the tow has filaments with a round cross-sectional shape and an SSAi of less than 1.60. In some aspects, the tow has filaments with a hexagon cross-sectional shape and an SSAi of less than 1.80. In some aspects, the tow has filaments with a pentagon cross-sectional shape and an SSAi of less than 1.90.

[0007] In some embodiments, the present disclosure is directed to a tow bale comprising the tow. The tow may be a cellulose acetate tow comprising cellulose acetate filaments, the tow having: a degree of substitution from 2.0 to 2.9; a denier per filament (dpf) from greater than 7.0 to 12.5; a total denier from 10,000 to 100,000; and wherein the cellulose acetatefilaments have a cross-sectional shape with an SSAi of less than 2.00, where SSAi = measured perimeter (p) / perimeter of circle of equivalent area (p); and further wherein the cross-sectional shape is not Y-shaped. In some aspects, the DPF is from 8.0 to 12.5, from 9.0 to 12.5, or from 9.0 to 12.0. In some aspects, the total denier is from 15,000 to 100,000, from 15,000 to 80,000, from 20,000 to 60,000, or from 25,000 to 40,000. In some aspects, the cross-sectional shape is polygonal. In some aspects, the cross-sectional shape is C-shaped. The cellulose acetate may have a degree of substitution from 2.3 to 2.7. In some aspects, the SSAi is from 1.00 to 2.00, from 1.20 to 1.90, or from 1.25 to 1.80. In some aspects, the tow has a round cross-sectional shape and an SSAi of less than 1.60. In some aspects, the tow has filaments with a hexagon cross-sectional shape and an SSAi of less than 1.80. In some aspects, the tow has filaments with a pentagon cross-sectional shape and an SSAi of less than 1.90.

[0008] In some embodiments, the present disclosure is directed to a debaled cellulose acetate tow. The tow may be a cellulose acetate tow comprising cellulose acetate filaments, the tow having: a degree of substitution from 2.0 to 2.9; a denier per filament (dpf) from greater than 7.0 to 12.5; a total denier from 10,000 to 100,000; and wherein the cellulose acetate filaments have a cross-sectional shape with an SSAi of less than 2.00, where SSAi = measured perimeter (p) / perimeter of circle of equivalent area (p); and further wherein the cross-sectional shape is not Y-shaped. In some aspects, the DPF is from 8.0 to 12.5, from 9.0 to 12.5, or from 9.0 to 12.0. In some aspects, the total denier is from 15,000 to 100,000, from 15,000 to 80,000, from 20,000 to 60,000, or from 25,000 to 40,000. In some aspects, the cross-sectional shape is polygonal. In some aspects, the cross-sectional shape is a C-shaped. The cellulose acetate may have a degree of substitution from 2.3 to 2.7. In some aspects, the SSAi is from 1.00 to 2.00, from 1.20 to 1.90, or from 1.25 to 1.80. In some aspects, the tow has filaments with a round cross-sectional shape and an SSAi of less than 1.60. In some aspects, the tow has filaments with a hexagon cross-sectional shape and an SSAi of less than 1.80. In some aspects, the tow has a pentagon cross-sectional shape and an SSAi of less than 1.90. The debaled cellulose acetate tow may have a uniform uncrimping energy of less than 400 gcm / cm, preferably less than 300 gcm / cm.

[0009] In some embodiments, the present disclosure is directed to a filter comprising tow. The tow may be a cellulose acetate tow comprising cellulose acetate filaments, the tow having: a degree of substitution from 2.0 to 2.9; a denier per filament (dpf) from greater than 7.0 to 12.5; a total denier from 10,000 to 100,000; and wherein the cellulose acetate filamentshave a cross-sectional shape with an SSAi of less than 2.00, where SSAi = measured perimeter (p) / perimeter of circle of equivalent area (p); and further wherein the cross-sectional shape is not Y-shaped. In some aspects, the DPF is from 8.0 to 12.5, from 9.0 to 12.5, or from 9.0 to 12.0. In some aspects, the total denier is from 15,000 to 100,000, from 15,000 to 80,000, from 20,000 to 60,000, or from 25,000 to 40,000. In some aspects, the cross-sectional shape is polygonal. In some aspects, the cross-sectional shape is a C-shaped. The cellulose acetate may have a degree of substitution from 2.3 to 2.7. In some aspects, the SSAi is from 1.00 to 2.00, from 1.20 to 1.65, or from 1.25 to 1.65. In some aspects, the tow has filaments with a round cross-sectional shape and an SSAi of less than 1.80. In some aspects, the tow has a hexagon cross-sectional shape and an SSAi of less than 1.90. In some aspects, the tow has filaments with a pentagon cross-sectional shape and an SSAi of less than 1.60. The debaled cellulose acetate tow has a uniform uncrimping energy of less than 400 gcm / cm, preferably less than 300 gcm / cm. In some aspects, the filter has an encapsulated pressure drop at a target weight of 50 grams / 100 rods of less than 300 mm water. In some aspects, the tow has filaments with a round cross-sectional shape and an encapsulated pressure drop at a target weight of 50 grams / 100 rods of less than 300 mm water and the tow may have an SSAi of less than 1.80. In some aspects, the tow has a hexagon cross-sectional shape and an encapsulated pressure drop at a target weight of 50 grams / 100 rods of less than 60 mm water and the tow may have an SSAi of less than 1.60. In some aspects, the tow has filaments with a pentagon cross-sectional shape and an encapsulated pressure drop at a target weight of 50 grams / 100 rods of less than 300 mm water and the tow may have an SSAi of less than 2.00.BRIEF DESCRIPTION OF THE FIGURES

[0010] In the following detailed description, embodiments of the invention are described referring to the following figures:

[0011] FIG. l is a schematic illustration of a tow production process according to the present disclosure.

[0012] FIG. 2 is a chart reporting results from Example 1.

[0013] FIG. 3 is a chart reporting results from Example 2.DETAILED DESCRIPTION OF THE INVENTIONIntroduction

[0014] The present disclosure is directed to a cellulose acetate tow, method for forming cellulose acetate tow, cellulose acetate tow bales, debaled cellulose acetate tow, and filters formed from cellulose acetate tow. As described further herein, the present disclosure is directed to cellulose acetate tow comprised of cellulose acetate filaments. The cellulose acetate tow has a degree of substitution from 2.0 to 2.9, e.g., from 2.3 to 2.7. The cellulose acetate tow has a denier per filament (DPF) of greater than 7.0 to 12.5, e.g., from 8.0 to 12.5, from 9.0 to 12.5, or from 9.0 to 12.0. The cellulose acetate tow has a total denier from 10,000 to 100,000, e.g., from 15,000 to 100,000, from 15,000 to 80,000, from 20,000 to 60,000, or from 25,000 to 40,000. The cellulose acetate tow is comprised of cellulose acetate filaments having a cross-sectional shape that is not the standard Y-shape. In addition to the different shape, the filaments have a specific surface area index (SSAi) of less than 2.00. This SSAI is measured by taking the measured perimeter (p) and dividing it by the perimeter of circle of equivalent area (p). Various cross-sectional shapes may be used, so long as they meet the SSAi value of less than 2.00.

[0015] As described herein, cellulose acetate tow is frequently used to make filters for both traditional cigarettes and heat-not-burn devices. In both traditional cigarettes and heat-not-bum devices, the draw resistance that a user experiences may be measured by measuring the encapsulated pressure drop (EPD). A greater pressure drop indicates a tighter raw while a lesser pressure drop indicates a looser draw. EPD is measured in mm water (gauge) and is desirably substantially uniform across the filters manufactured. Generally, lesser pressure drop is desired but to achieve such lesser pressure drop, the DPF of the tow is increased. Without being bound by theory, it has been discovered that by using filaments having a cross-sectional shape other than the traditional Y-shape, the pressure drop across a filter incorporating tow having such filaments may be decreased as compared to a tow having the same DPF but a Y-shape cross-sectional shape. These cross-sectional shapes other than Y-shape also have a lesser SSAi, leading to further benefits.

[0016] The cross-sectional shape may be any shape other than Y-shape, as described herein, and may specifically include a round, pentagon, or hexagon shape. Further shapes include polygonal shapes, crescent shaped, C-shaped, T-shaped, and X-shaped. The cross-sectional shape is used in the industry and understood by one skilled in the art to refer to the cross-sectional shape of the jet through which the filament is product. The actual filament cross-sectional shape may not be an exactly symmetric pentagon, for example, though one skilled in the art would be able to readily determine that such a filament was made from a jethaving a pentagon shape. Similarly, a filament made from a round-shaped jet may not have a perfectly round cross-sectional shape and may have several lobes, despite generally being round. Again, one skilled in the art would be able to readily determine that such a filament was made from a jet having a round shape.

[0017] The SSAi of the filament may range from 1.00 to 2.00, from 1.05 to 2.00, from 1.10 to 2.00, from 1.15 to 2.00, from 1.20 to 2.00, from 1.25 to 2.00, from 1.30 to 2.00, from 1.35 to 2.00, from 1.40 to 2.00, from 1.45 to 2 .00, from 1.50 to 2.00, from 1.55 to 2.00, from 1.60 to 2.00, from 1.65 to 2.00, from 1.70 to 2 .00, from 1.80 to 2.00, from 1.85 to 2.00, from 1.90 to 2.00, from 1.95 to 2.00, from 1.00 to 1 .95, from 1.05 to 1.95, from 1.10 to 1.95, from 1.15 to 1.95, from 1.20 to 1.95, from 1.25 to 1 .95, from 1.30 to 1.95, from 1.35 to 1.95, from 1.40 to 1.95, from 1.45 to 1.95, from 1.50 to 1 .95, from 1.55 to 1.95, from 1.60 to 1.95, from 1.65 to 1.95, from 1.70 to 1.95, from 1.75 to 1 .95, from 1.80 to 1.95, from 1.85 to 1.95, from 1.90 to 1.95, from 1.00 to 1.90, from 1.05 to 1 .90, from 1.10 to 1.90, from 1.15 to 1.90, from 1.20 to 1.90, from 1.25 to 1.90, from 1.30 to 1 .90, from 1.35 to 1.90, from 1.40 to 1.90, from 1.45 to 1.90, from 1.50 to 1.90, from 1.55 to 1 .90, from 1.60 to 1.90, from 1.65 to 1.90, from 1.70 to 1.90, from 1.75 to 1.90, from 1.80 to 1 .90, from 1.85 to 1.90, from 1.00 to 1.85, from 1.05 to 1.85, from 1.10 to 1.85, from 1.15 to 1 .85, from 1.20 to 1.85, from 1.25 to 1.85, from 1.30 to 1.85, from 1.35 to 1.85, from 1.40 to 1 .85, from 1.45 to 1.85, from 1.50 to 1.85, from 1.55 to 1.85, from 1.60 to 1.85, from 1.65 to 1 .85, from 1.70 to 1.85, from 1.75 to 1.85, from 1.80 to 1.85, from 1.00 to 1.80, from 1.05 to 1 .80, from 1.10 to 1.80, from 1.15 to 1.80, from 1.20 to 1.80, from 1.25 to 1.80, from 1.30 to 1 .80, from 1.35 to 1.80, from 1.40 to 1.80, from 1.45 to 1.80, from 1.50 to 1.80, from 1.55 to 1 .80, from 1.60 to 1.80, from 1.65 to 1.80, from 1.70 to 1.80, from 1.75 to 1.80, from 1.00 to 1 .75, from 1.05 to 1.75, from 1.10 to 1.75, from 1.15 to 1.75, from 1.20 to 1.75, from 1.25 to 1 .75, from 1.30 to 1.75, from 1.35 to 1.75, from 1.40 to 1.75, from 1.45 to 1.75, from 1.50 to 1 .75, from 1.55 to 1.75, from 1.60 to 1.75, from 1.65 to 1.75, from 1.70 to 1.75, from 1.05 to 1 .70, from 1.10 to 1.70, from 1.15 to 1.70, from 1.20 to 1.70, from 1.25 to 1.70, from 1.30 to 1 .70, from 1.35 to 1.70, from 1.40 to 1.70, from 1.45 to 1.70, from 1.50 to 1.70, from 1.55 to 1 .70, from 1.60 to 1.70, from 1.65 to 1.70, from 1.00 to 1.65, from 1.05 to 1.65, from 1.10 to 1 .65, from 1.15 to 1.65, from 1.20 to 1.65, from 1.25 to 1.65, from 1.30 to 1.65, from 1.35 to 1 .65, from 1.40 to 1.65, from 1.45 to 1.65, from 1.50 to 1.65, from 1.55 to 1.65, from 1.60 to 1 .65, from 1.00 to 1.60, from 1.05 to 1.60, from 1.10 to 1.60, from 1.15 to 1.60, from 1.20 to 1 .60, from 1.25 to 1.60, from 1.30 to 1.60, from 1.35 to 1.60, from 1.40 to 1.60, from 1.45 to 1 .60, from 1.50 to 1.60, from 1.55 to 1.60, from1.00 to 1.55, from 1.05 to 1.55, from 1.10 to 1.55, from 1.15 to 1.55, from 1.20 to 1.55, from 1.25 to 1.55, from 1.30 to 1.55, from 1.35 to 1.55, from 1.40 to 1.55, from 1.45 to 1.55, from 1.50 to 1.55, from 1.00 to 1.50, from 1.05 to 1.50, from 1.10 to 1.50, from 1.15 to 1.50, from 1.20 to 1.50, from 1.25 to 1.50, from 1.30 to 1.50, from 1.35 to 1.50, from 1.40 to 1.50, from 1.45 to 1.50, from 1.00 to 1.45, from 1.05 to 1.45, from 1.10 to 1.45, from 1.15 to 1.45, from 1.20 to 1.45, from 1.25 to 1.45, from 1.30 to 1.45, from 1.35 to 1.45, from 1.40 to 1.45, from 1.00 to 1.40, from 1.05 to 1.40, from 1.10 to 1.40, from 1.15 to 1.40, from 1.20 to 1.40, from 1.25 to 1.40, from 1.30 to 1.40, from 1.35 to 1.40, from 1.00 to 1.35, from 1.05 to 1.35, from 1.10 to 1.35, from 1.15 to 1.35, from 1.20 to 1.35, from 1.25 to 1.35, from 1.30 to 1.35, from 1.00 to 1.30, from 1.05 to 1.30, from 1.10 to 1.30, from 1.15 to 1.30, from 1.20 to 1.30, from 1.25 to 1.30, from 1.00 to 1.25, from 1.05 to 1.25, from 1.10 to 1.25, from 1.10 to 1.25, from 1.20 to 1.25, from 1.00 to 1.20, from 1.05 to 1.20, from 1.10 to 1.20, from 1.15 to 1.20, from 1.00 to 1.15, from 1.05 to 1.15, from 1.10 to 1.15, from 1.00 to 1.10, from 1.05 to 1.10, or from 1.00 to 1.05.

[0018] In some specific aspects, the cellulose acetate filaments have a round cross-sectional shape and an SSAi of less than 1.60. In some specific aspects, the cellulose acetate filaments have a hexagon cross-sectional shape and an SSAi of less than 1.80. In some specific aspects, the cellulose acetate filaments have a pentagon cross-sectional shape and an SSAi of less than 1.90.

[0019] The present disclosure is also directed to tow bales having the tow described herein. Following baling, as described further herein, the tow is debaled. During debaling, the uniform uncrimping energy (UCE) of the tow may be measured. The UCE is a valuable measurement because it measures uniformity of the tow. Again, this indicates that a user will have a similar experience across filters made from the same bale of tow. The debaled cellulose acetate tow may have a UCE of less than 400 gcm / cm, e.g., less than 300 gcm / cm, measured as described further herein.

[0020] The present disclosure is also directed to a formed from the debaled tow or tow described herein. The filter may have an EPD at a target weight of 50 grams / 100 rods of less than 200 mm water. In some aspects, the tow has filaments with a round cross-sectional shape and an encapsulated pressure drop at a target weight of 50 grams / 100 rods of less than 200 mm water. In some aspects, the tow has filaments with a hexagon cross-sectional shape and an encapsulated pressure drop at a target weight of 50 grams / 100 rods of less than 200mm water and the tow may have an SSAi of less than 1.60. In some aspects, the tow has filaments with a pentagon cross-sectional shape and an encapsulated pressure drop at a target weight of 50 grams / 100 rods of less than 200 mm water and the tow may have an SSAi of less than 1.70.Cellulose Acetate

[0021] As described herein, the present disclosure relates to tow, tow bands, tow bales, and cigarette filters having tow with filaments having a certain cross-sectional shape and SSAi. Cellulose acetate, as used herein, refers to cellulose diacetate, Cellulose acetate may be prepared by known processes, including those disclosed in U.S. Patent No. 2,740,775 and in U.S. Publication No. 2013 / 0096297, the entireties of which are incorporated herein by reference. Typically, acetylated cellulose is prepared by reacting cellulose with an acetylating agent in the presence of a suitable acidic catalyst and then de-esterifying.

[0022] The cellulose may be sourced from a variety of materials, including cotton linters, a softwood or from a hardwood. Softwood is a generic term typically used in reference to wood from conifers (i.e., needle-bearing trees from the order Pinales). Softwood-producing trees include pine, spruce, cedar, fir, larch, douglas-fir, hemlock, cypress, redwood and yew. Conversely, the term hardwood is typically used in reference to wood from broad-leaved or angiosperm trees. The terms “softwood” and “hardwood” do not necessarily describe the actual hardness of the wood. While, on average, hardwood is of higher density and hardness than softwood, there is considerable variation in actual wood hardness in both groups, and some softwood trees can actually produce wood that is harder than wood from hardwood trees. One feature separating hardwoods from softwoods is the presence of pores, or vessels, in hardwood trees, which are absent in softwood trees. On a microscopic level, softwood contains two types of cells, longitudinal wood fibers (or tracheids) and transverse ray cells. In softwood, water transport within the tree is via the tracheids rather than the pores of hardwoods. In some aspects, a hardwood cellulose is preferred for acetylating.

[0023] Acylating agents can include both carboxylic acid anhydrides (or simply anhydrides) and carboxylic acid halides, particularly carboxylic acid chlorides (or simply acid chlorides). Suitable acid chlorides can include, for example, acetyl chloride, propionyl chloride, butyryl chloride, benzoyl chloride and like acid chlorides. Suitable anhydrides can include, for example, acetic anhydride, propionic anhydride, butyric anhydride, benzoic anhydride and like anhydrides. Mixtures of these anhydrides or other acylating agents canalso be used in order to introduce differing acyl groups to the cellulose. Mixed anhydrides such as, for example, acetic propionic anhydride, acetic butyric anhydride and the like can also be used for this purpose in some embodiments.

[0024] In most cases, the cellulose is exhaustively acetylated with the acetylating agent to produce a derivatized cellulose having a high degree of substitution (DS) value, such as from 2.4 to 3, along with some additional hydroxyl group substitution (e.g., sulfate esters) in some cases. Exhaustively acetylating the cellulose refers to an acetylation reaction that is driven toward completion such that as many hydroxyl groups as possible in cellulose undergo an acetylation reaction.

[0025] Suitable acidic catalysts for promoting the acetylation of cellulose often contain sulfuric acid or a mixture of sulfuric acid and at least one other acid. Other acidic catalysts not containing sulfuric acid can similarly be used to promote the acetylation reaction. In the case of sulfuric acid, at least some of the hydroxyl groups in the cellulose can become initially functionalized as sulfate esters during the acetylation reaction. Once exhaustively acetylated, the cellulose is then subjected to a controlled partial de-esterification step, generally in the presence of a de-esterification agent, also referred to as a controlled partial hydrolysis step.

[0026] De-esterification, as used herein, refers to a chemical reaction during which one or more of the ester groups of the intermediate cellulosic ester are cleaved from the cellulose acetate and replaced with a hydroxyl group, resulting in a cellulose acetate product having a (second) DS of less than 3. "De-esterifying agent," as used herein, refers to a chemical agent capable of reacting with one or more of the ester groups of the cellulose acetate to form hydroxyl groups on the intermediate cellulosic ester. Suitable de-esterifying agents include low molecular weight alcohols, such as methanol, ethanol, isopropyl alcohol, pentanol, R-OH, wherein R is Cl to C20 alkyl group, and mixtures thereof. Water and a mixture of water and methanol may also be used as the de-esterifying agent. Typically, most of these sulfate esters are cleaved during the controlled partial hydrolysis used to reduce the amount of acetyl substitution. The reduced degree of substitution may range from 0.5 to 3.0, e.g., from 1.3 to 3, from 1.3 to 2.9, from 1.5 to 2.9 or from 2 to 2.6. For purposes of this disclosure, the degree of substitution is typically from 1.3 to 2.9 since below 1.3, natural degradation may occur. The degree of substitution may be selected based on the at least one organic solvent to be used in the binder composition. For example, when acetone is used as the organic solvent, thedegree of substitution may range from 2.2 to 2.65. As used herein, “degradation” may refer to any degradation mechanism and rate, including photo chemical degradation, biodegradation, or any form of degradation.

[0027] The number average molecular weight of the cellulose acetate may range from 30,000 amu to 100,000 amu, e.g., from 50,000 amu to 80,000 amu and may have a poly dispersity from 1.5 to 2.5, e.g., from 1.75 to 2.25 or from 1.8 to 2.2. All molecular weight recited herein, unless otherwise specified, are number average molecular weights. The molecular weight may be selected based on the desired hardness of the final tow or filter rod. Although greater molecular weight leads to increased hardness, greater molecular weight also increases viscosity. The cellulose acetate may be provided in powder or flake form.

[0028] In some aspects, blends of different molecular weight cellulose acetate flake or powder may be used. Accordingly, a blend of high molecular weight cellulose acetate, e.g., a cellulose acetate having a molecular weight above 60,000 amu, may be blended with a low molecular weight cellulose acetate, e.g., a cellulose acetate having a molecular weight below 60,000 amu. The ratio of high molecular weight cellulose acetate to low molecular weight cellulose acetate may vary but may generally range from 1 : 10 to 10:1; e.g., from 1 :5 to 5: 1 or from 1:3 to 3:1. Blends of different cellulose acetates may also be used and may include two, three, four, or more different cellulose acetates in varied ratios. In some aspects, one cellulose acetate may be present in a majority while other cellulose acetates are present in smaller amounts. Different types of cellulose esters may also be used.Cellulose Acetate Fibers, Tow, and Tow Bales

[0029] Referring to FIG. 1, a tow process 100 is shown. Dope preparation station 102 feeds a plurality of cabinets 104 (only three shown, without being limited). In cabinets 104, fibers are produced. The fibers are taken-up on take-up roller 106. These fibers are lubricated at a lubrication station 108 with a finish (discussed in greater detail below). These lubricated fibers are bundled together to form a tow on a roller 110. The tow is plasticized at a plasticizing station 112 (discussed in greater detail below). The tow is then passed through a crimper 114 (discussed in greater detail below). In some embodiments, the fibers and / or tow can be inspected at station 116. The tow is dried in dryer 118. In some embodiments, the dried tow can be inspected upon exiting dryer 118. The dried crimped tow is then baled at baling station 120. Although the tow inspection is shown between the plasticizing station 112 and the dryer 118 in this embodiment, the tow inspection can also or alternatively beperformed at different points in the process. The tow inspection may comprise measuring and / or checking any of the parameters described herein, including measuring the SSAi.

[0030] There are a number of methods of forming fibers from cellulose acetate which may be employed to form the tow of the present disclosure. In some embodiments, to form fibers from cellulose acetate, a dope is formed by dissolving the cellulose acetate flake or powder in a solvent to form a dope solution. The dope solution is typically a highly viscous solution. The solvent of the dope solution may be selected from the group consisting of water, acetone, methylethyl ketone, methylene chloride, dioxane, dimethyl formamide, methanol, ethanol, glacial acetic acid, supercritical carbon dioxide, any suitable solvent capable of dissolving the aforementioned polymers, and combinations thereof. In some aspects, the solvent is acetone or a combination of acetone and up to 5 wt.% water. The dope is then filtered and deaerated prior to being spun to form fibers, referred to as solventspinning. The dope may be spun in a spinner comprising one or more cabinets, each cabinet comprising a spinneret. The spinneret comprises holes that affect the rate at which the solvent evaporates from the fibers.

[0031] The solvent may be included in the dope in an amount from 60 to 90 % by weight, e.g., from 60 to 85 % by weight, from 60 to 80 % by weight, from 60 to 75 % by weight, from 60 to 70 % by weight, from 60 to 65 % by weight, from 65 to 90 % by weight, from 70 to 90 % by weight, from 75 to 90 % by weight, from 80 to 90% by weight, or from 85 to 90 % by weight. All values in between are also contemplated and included.

[0032] The cellulose acetate may be included in the dope in an amount sufficient to retain the desired properties of the tow, tow band, or cigarette filter, e.g., filtration of the cigarette filter. For example, the cellulose acetate may be present from 0.1 to 39.9 % by weight of the dope, e.g., from 0.1 to 37.5 % by weight, from 0.1 to 35 % by weight, from 0.1 to 30 % by weight, from 0.1 to 25 % by weight by weight, from 0.1 to 20 % by weight, from 0.1 to 15 % by weight, from 0.1 to 10 % by weight, from 0.1 to 7.5 % by weight, or from 0.1 to 5 % by weight. In further aspects, the lower limit of the cellulose acetate may be at least 0.5 % by weight, at least 0.75 % by weight, at least 1 % by weight, at least 2 % by weight, at least 3 % by weight, at least 5 % by weight, at least 10 % by weight, at least 15 % by weight, at least 20 % by weight, at least 25 % by weight, at least 30 % by weight, at least 35 % by weight, at least 37.5 %, at least 39 %, or at least 39.5 %. All other values and ranges in between the above cited values are also included and contemplated.

[0033] Pigments may also be added to the dope. The dope may comprise, for example, from 5 to 40 wt.% cellulose acetate and from 60 to 90 wt.% solvent. Pigments, when added, may be present from 0.1 to 5 wt.%, e.g., from 0.1 to 4 wt.%, from 0.1 to 3 wt.% from 0.1 to 2 wt.%, from 0.5 to 5 wt.%, from 0.5 to 4 wt.%, from 0.5 to 3 wt.%, from 0.5 to 2 wt.%, from 1 to 5 wt.%, from 1 to 4 wt.%, from 1 to 3 wt.% or from 1 to 2 wt.%. The pigment added to the dope is not particularly limited, and any conventional pigment may be used. Examples of common, suitable pigments include calcium carbonate, diatomaceous earth, magnesium oxide, zinc oxide, and barium sulfate.

[0034] Generally, the production of a bale of tow may involve spinning fibers from the dope, forming a tow containing the fibers, forming a tow band from the fibers, crimping the tow band, and baling the crimped tow band. Within said production, optional steps may include, but are not limited to, warming the fibers after spinning, applying a finish or additive to the fibers and / or tow band prior to crimping, and conditioning the crimped tow band. The parameters of at least these steps are important for producing desirable bales. The tow may have a primary crimp from 10 to 50 crimps per 25 mm, e.g., 15 to 45 crimps per 25 mm, from 20 to 40 crimps per 25 mm, or from 35 to 35 crimps per 25 mm. The tow may also have a secondary crimp, such as that described in W00056962, the entirety of which is incorporated by reference herein.

[0035] It should be noted that bales may vary in size and shape as needed for further processing. In some embodiments, bales may have dimensions ranging from 30 inches (76 cm) to 60 inches (152 cm) in height, 46 inches (117 cm) to 56 inches (142 cm) in length, and 35 inches (89 cm) to 45 inches (114 cm) in width. In some embodiments, bales may range in weight from 900 pounds (408 kg) to 2100 pounds (953 kg). In some embodiments, bales may have a density greater than 300 kg / m3 (18.8 lb / ft3).Fibers

[0036] The structure of the cellulose acetate fibers for use in the present disclosure is not particularly limited, and various known fiber structures may be employed. For example, the tow band may utilize fibers having a broad range of denier per filament (dpf). In some embodiments, the tow band has from greater than 7.0 to 12.5 dpf, e.g., from 7.5 to 12.3 dpf, from 7.5 to 12.0 dpf, from 7.5 to 11.5 dpf, from 7.5 to 11.0 dpf, from 7.5 to 10.5 dpf, from 7.5 to 10.0 dpf, from 7.5 to 9.5 dpf, from 7.5 to 9.0 dpf, from 7.5 to 8.5 dpf, from 8.0 to 12.5 dpf, from 8.0 to 12.3 dpf, from 8.0 to 12.0 dpf, from 8.0 to 11.5 dpf, from 8.0 to 11.0 dpf,from 8.0 to 10.5 dpf, from 8.0 to 10.0 dpf, from 8.0 to 9.5 dpf, from 8.0 to 9.0 dpf, from 8.0 to 8.5 dpf, from 8.5 to 12.5 dpf, from 8.5 to 12.3 dpf, from 8.5 to 12.0 dpf, from 8.5 to 11.5 dpf, from 8.5 to 11.0 dpf, from 8.5 to 10.5 dpf, from 8.5 to 10.0 dpf, from 8.5 to 9.5 dpf, from 8.5 to 9.0 dpf, from 9.0 to 12.5 dpf, from 9.0 to 12.3 dpf, from 9.0 to 12.0 dpf, from 9.0 to 11.5 dpf, from 9.0 to 11.0 dpf, from 9.0 to 10.5 dpf, from 9.0 to 10.0 dpf, from 9.0 to 9.5 dpf, from 9.5 to 12.5 dpf, from 9.5 to 12.3 dpf, from 9.5 to 12.0 dpf, from 9.5 to 11.5 dpf, from 9.5 to 11.0 dpf, from 9.5 to 10.5 dpf, from 9.5 to 10.0 dpf, from 10.0 to 12.5 dpf, from 10.0 to 12.3 dpf, from 10.0 to 12.0 dpf, from 10.0 to 11.5 dpf, from 10.0 to 11.0 dpf, from 10.0 to 10.5 dpf, from 10.5 to 12.5 dpf, from 10.5 to 12.3 dpf, from 10.5 to 12.0 dpf, from 10.5 to 11.5 dpf, from 10.5 to 11.0 dpf, from 11.0 to 12.5 dpf, from 11.0 to 12.3 dpf, from 11.0 to 12.0 dpf, from 11.0 to 11.5 dpf, from 11.0 to 12.5 dpf, from 11.0 to 12.3 dpf, from 11.0 to 12.0 dpf, from 11.0 to 11.5 dpf, from 11.5 to 12.5 dpf, from 11.5 to 12.3 dpf, from 11.5 to 12.0 dpf, from 11.5 to 11.5 dpf, from 11.5 to 12.5 dpf, from 11.5 to 12.3 dpf, from 11.5 to 12.0 dpf, from 12.0 to 12.5 dpf, or from 12.0 to 12.3 dpf.

[0037] The fibers for use in the present disclosure may have any suitable cross-sectional shape, including, but not limited to, circular, substantially circular, crenulated, ovular, substantially ovular, polygonal (pentagon, hexagon), substantially polygonal, dog-bone, “Y,” “X,” “K,” “C,” “T”, crescent moon, multi-lobe, and any hybrid thereof. As used herein, the term “multi-lobe” refers to a cross-sectional shape having a point (not necessarily in the center of the cross-section) from which at least two lobes extend (not necessarily evenly spaced or evenly sized). The cross-sectional shape of the jet used to form the filament may vary from the final appearance of the fiber / filament as described herein.

[0038] As noted above, fibers for use in the present disclosure may be produced by any method known to one skilled in the art. As noted, in some embodiments, fibers may be produced by spinning a dope through a spinneret. As used herein, the term “dope” refers to a cellulose acetate solution and / or suspension from which fibers are produced. In some embodiments, a dope may comprise cellulose acetate and solvents. In some embodiments, a dope for use in conjunction with the present disclosure may comprise cellulose acetate, solvents, and additives. In some embodiments, the cellulose acetate may be at a concentration in the dope ranging from 10 to 40 wt. percent (e.g., from 20 to 30 wt.%, from 25 to 40 wt.%, from 25 to 30 wt.%), and the solvent may be at a concentration from 60 to 90 wt.% (e.g., 60 to 80 wt.%, 70 to 80 wt.%, 80 to 90 wt.%). In some embodiments, the dope may be heated toa temperature ranging from 40° C to 100° C (e.g., from 45° C to 95° C, from 50° C to 90° C, from 55° C to 85° C, from 60° C to 80° C).

[0039] Suitable solvents may include, but not be limited to, water, acetone, methylethyl ketone, methylene chloride, dioxane, dimethyl formamide, methanol, ethanol, glacial acetic acid, supercritical CO2, any suitable solvent capable of dissolving the aforementioned polymers, or any combination thereof. By way of nonlimiting example, a solvent for cellulose acetate may be an acetone / methanol mixture.

[0040] Some embodiments of the present disclosure may involve treating fibers to achieve surface functionality on the fibers. In some embodiments, fibers may comprise a surface functionality including, but not limited to, biodegradability sites (e.g., defect sites to increase surface area to enhance biodegradability), chemical handles (e.g., carboxylic acid groups for subsequent functionalization), active particle binding sites (e.g., sulfide sites binding gold particles or chelating groups for binding iron oxide particles), sulfur moieties, or any combination thereof. One skilled in the art should understand the plurality of methods and mechanisms to achieve surface functionalities. Some embodiments may involve dipping, spraying, ionizing, functionalizing, acidizing, hydrolyzing, exposing to a plasma, exposing to an ionized gas, or any combination thereof to achieve surface functionalities. Suitable chemicals to impart a surface functionality may be any chemical or collection of chemicals capable of reacting with cellulose acetate including, but not limited to, acids (e.g., sulfuric acid, nitric acid, acetic acid, hydrofluoric acid, hydrochloric acid, and the like), reducing agents (e.g., LiAlH4, NaBH4, H2 / Pt, and the like), Grignard reagents (e.g., CH3MgBr, and the like), trans-esterification reagent, amines (e.g., R — NH3 like CH3NH3), or any combination thereof. Exposure to plasmas and / or ionized gases may react with the surface, produce defects in the surface, or any combination thereof. Said defects may increase the surface area of the fibers which may yield higher loading and / or higher filtration efficacy in the final filter products.

[0041] Some embodiments of the present disclosure may involve applying a finish to the fibers. Suitable finishes may include, but not be limited to, at least one of the following: oils (e.g., mineral oils or liquid petroleum derivatives), water, additives, or any combination thereof. Examples of suitable mineral oils may include, but not be limited to, water white (i.e., clear) mineral oil having a viscosity of 80-95 SUS (Sabolt Universal Seconds) measured at 38° C (100° F.). Examples of suitable emulsifiers may include, but not be limited to,sorbitan monolaurate, e.g., SPAN® 20 (available from Croda, Wilmington, Del.), poly(ethylene oxide) sorbitan monolaurate, e.g., TWEEN® 20 (available from Croda, Wilmington, Del.). The water may be de-mineralized water, de-ionized water, or otherwise appropriately filtered and treated water. The lubricant or finish may be applied by spraying or wiping. Generally, the lubricant or finish is added to the fiber prior to forming the fibers into tow.

[0042] In some embodiments of the present disclosure, finish may be applied as a neat finish or as a finish emulsion in water. As used herein, the term “neat finish” refers to a finish formulation without the addition of excess water. It should be noted that finish formulations may comprise water. In some embodiments, finish may be applied neat followed by applying water separately.

[0043] In some embodiments of the present disclosure, a finished emulsion may comprise less than 98% water, less than 95%, less than 92%, or less than 85%. In some embodiments, it may be advantageous in later steps to have fibers having a lower weight percentage of moisture (e.g., 5% to 25% w / w of the tow band), of which water is a contributor. The water content of the finished emulsion may be at least one parameter that may assist in achieving said weight percentage of moisture in the fibers. Therefore, in some embodiments, a finished emulsion may comprise less than 92% water, less than 85% water, or less than 75% water.Tow

[0044] Once the dope is formed and solvent-spun, the solvent is evaporated and the dope is spun and extruded to form a plurality of extruded fibers, referred to as tow.

[0045] The cellulose acetate may be included in the tow in an amount sufficient to retain the desired properties of the tow, tow band, or cigarette filter, e.g., filtration of the cigarette filter. For example, the cellulose acetate may be present from 0.1 to 99 % by weight of the tow, e.g., from 0.1 to 95 % by weight, from 0.1 to 90 % by weight, from 0.1 to 85 % by weight, from 0.1 to 80 % by weight by weight, from 0.1 to 75 % by weight, from 0.1 to 70 % by weight, from 0.1 to 65 % by weight, from 0.1 to 60 % by weight, from 0.1 to 55 % by weight, from 0.1 to 50 % by weight, from 0.1 to 45 % by weight, from 0.1 to 40 % by weight, from 0.1 to 35 % by weight, from 0.1 to 30 % by weight, from 0.1 to 25 % by weight, from 0.1 to 20 % by weight, from 0.1 to 15 % by weight, from 0.1 to 10 % by weight, or from 0.1 to 5 % by weight. In further aspects, the lower limit of the cellulose acetate may be at least 0.5 % by weight, at least 0.75 % by weight, at least 1 % by weight, at least 2 % by weight, atleast 3 % by weight, at least 5 % by weight, at least 10 % by weight, at least 15 % by weight, at least 20 % by weight, at least 25 % by weight, at least 30 % by weight, at least 35 % by weight, at least 40 % by weight, at least 45 % by weight, at least 50 % by weight, or greater. All other values and ranges in between the above cited values are also included and contemplated. Furthermore, the above included ranges for the tow also apply to the tow band and filter rod incorporated into a cigarette filter.

[0046] The tow, tow band, filter rod, and cigarette filter may also comprise additives. The additives may be present in an amount from 0.01 to 25 % by weight, e.g., from 0.01 to 20 % by weight, from 0.1 to 20 % by weight, from 0.1 to 15 % by weight, from 0.1 to 10 % by weight, or from 0.1 to 5 % by weight. In further aspects, the lower limit of the cellulose acetate may be at least 0.5 % by weight, at least 0.75 % by weight, at least 1 % by weight, at least 2 % by weight, at least 3 % by weight, at least 5 % by weight, at least 10 % by weight, at least 15 % by weight, at least 20 % by weight, at least 25 % by weight, at least 30 % by weight, at least 35 % by weight, at least 40 % by weight, at least 45 % by weight, at least 50 % by weight, or greater. All other values and ranges in between the above cited values are also included and contemplated.

[0047] Once the tow is formed, it may be combined to form a tow band which comprises a plurality of tow filaments. In some embodiments, the tow band is from 10,000 to 100,000 total denier, e.g., from 15,000 to 100,000, from 15,000 to 80,000, from 20,000 to 100,000, from 25,000 to 100,000, from 30,000 to 100,000, from 10,000 to 90,000, from 15,000 to 90,000, from 20,000 to 90,000, from 25,000 to 90,000, from 30,000 to 90,000, from 10,000 to 90,000, from 15,000 to 90,000, from 20,000 to 90,000, from 25,000 to 90,000, from 30,000 to 90,000, from 10,000 to 80,000, from 15,000 to 80,000, from 20,000 to 80,000, from 25,000 to 80,000, from 30,000 to 80,000, from 10,000 to 70,000, from 15,000 to 70,000, from 20,000 to 70,000, from 25,000 to 70,000, from 30,000 to 70,000, from 10,000 to 60,000, from 15,000 to 60,000, from 20,000 to 60,000, from 25,000 to 60,000, or from 30,000 to 60,000. In terms of upper limits, the tow band may be less than 100,000 total denier, e.g., less than 90,000, less than 80,000, less than 70,000, or less than 60,000. In terms of lower limits, the tow band may be greater than 10,000 total denier, e.g., greater than 15,000, greater than 20,000, greater than 25,000, or greater than 30,000.

[0048] In some embodiments, the tow can have a breaking strength between 3.5 kg and 25 kg, e.g. from 3.5 kg to 22.5 kg, from 3.5 kg to 20 kg, from 3.5 kg to 17.5 kg, from 3.5 kgto 15 kg, from 4 kg to 25 kg, from 4 kg to 22.5 kg, from 4 kg to 20 kg, from 4 kg to 17.5 kg, from 4 kg to 15 kg, from 4.5 kg to 25 kg, from 4.5 kg to 22.5 kg, from 4.5 kg to 20 kg, from 4.5 kg to 17.5 kg, from 4.5 kg to 15 kg, from 5 kg to 25 kg, from 5 kg to 22.5 kg, from 5 kg to 20 kg, from 5 kg to 17.5 kg, or from 5 kg to 15 kg. In terms of upper limits, the tow may have a breaking strength of less than 25 kg, e.g., less than 22.5 kg, less than 20 kg, less than 17.5 kg, or less than 15 kg. In terms of lower limits, the tow may have a breaking strength of greater than 3.5 kg, e.g. greater than 4 kg, greater than 4.5 kg, or greater than 5 kg.

[0049] In some embodiments of the present disclosure, a tow band may comprise more than one type of fiber. In some embodiments, the more than one type of fiber may vary based on dpf, cross-sectional shape, composition, treatment prior to forming the tow band, or any combination thereof. Examples of suitable additional fibers may include, but are not limited to, carbon fibers, activated carbon fibers, natural fibers, synthetic fibers, or any combination thereof. Some embodiments of the present disclosure may include crimping the tow band to form a crimped tow band. Crimping the tow band may involve using any suitable crimping technique known to those skilled in the art. These techniques may include a variety of apparatuses including, but not limited to, a stuffer box or a gear. Nonlimiting examples of crimping apparatuses and the mechanisms by which they work can be found in U.S. Pat. Nos.7,610,852 and 7,585,441, the entire contents and disclosures of which are incorporated herein by reference. Suitable stuffer box crimpers may have smooth crimper nip rolls, threaded or grooved crimper nip rolls, textured crimper nip rolls, upper flaps, lower flaps, or any combination thereof.

[0050] The configuration of the crimp may play a role in the processability of the final bale. Examples of crimp configurations may include, but not be limited to, lateral, vertical, some degree between lateral and vertical, random, or any combination thereof. As used herein, the term “lateral” when describing crimp orientation refers to crimp or fiber bends in the plane of the tow band. As used herein, the term “vertical” when describing a crimp orientation refers to crimp projecting outside of the plane of the tow band and perpendicular to the plane of the tow band. It should be noted that the terms lateral and vertical refer to general overall crimp orientation and may have deviation from said configuration by + / - 30 degrees.

[0051] In some embodiments of the present disclosure, a crimped tow band may comprise fibers with a first crimp configuration and fibers with a second crimp configuration.

[0052] In some embodiments of the present disclosure, a crimped tow band may comprise fibers with at least a vertical crimp configuration near the edges and fibers with at least a lateral crimp configuration near the center. In some embodiments, a crimped tow band may comprise fibers with a vertical crimp configuration near the edges and fibers with a lateral crimp configuration near the center.

[0053] The configuration of the crimp may be important for the processability of the final bale in subsequent processing steps, e.g., a lateral crimp configuration may provide better cohesion of fibers than a vertical crimp configuration unless further steps are taken to enhance cohesion. Methods for crimping tow bands with a substantially later crimp configuration are disclosed, for example, in U.S. Pub. No. 2013 / 0115452 and U.S. Pub. No.2015 / 0128964, each of which is incorporated herein in its entirety.

[0054] In some embodiments of the present disclosure, the fibers may be adhered to each other to provide better processability of the final bale. While adhesion additives may be used in conjunction with any crimp configuration, it may be advantageous to use adhesion additives with a vertical crimp configuration. In some embodiments, adhering may involve adhesion additives on and / or in the fibers. Examples of such adhesion additives may include, but not be limited to, binders, adhesives, resins, tackifiers, or any combination thereof. It should be noted that any additive described herein, or otherwise, capable of adhering two fibers together may be used, which may include, but not be limited to, active particles, active compounds, ionic resins, zeolites, nanoparticles, ceramic particles, softening agents, plasticizers, pigments, dyes, flavorants, aromas, controlled release vesicles, surface modification agents, lubricating agents, emulsifiers, vitamins, peroxides, biocides, antifungals, antimicrobials, antistatic agents, flame retardants, antifoaming agents, degradation agents, conductivity modifying agents, stabilizing agents, or any combination thereof. Some embodiments of the present disclosure may involve adding adhesive additives to the fibers (in, on, or both) by incorporating the adhesive additives into the dope, incorporating the adhesive additives into the finish, applying the adhesive additives to the fibers (before, after, and / or during forming the tow band), applying the adhesive additives to the tow band (before, after, and / or during crimping), or any combination thereof.

[0055] Adhesive additives may be included in and / or on the fibers at a concentration sufficient to adhere the fibers together at a plurality of contact points to provide better processability of the final bale. The concentration of adhesive additives to use may depend onthe type of adhesive additive and the strength of adhesion the adhesive additive provides. In some embodiments, the concentration of adhesive additive may range from a lower limit of 0.01%, 0.05%, 0.1%, or 0.25% to an upper limit of 5%, 2.5%, 1%, or 0.5% by weight of the tow band in the final bale. It should be noted that for additives that are used for more than adhesion, the concentration in the tow band in the final bale may be higher, e.g., 25% or less.

[0056] Further, some embodiments of the present disclosure may involve heating the fibers before, after, and / or during crimping. While said heating may be used in conjunction with any crimp configuration, it may be advantageous to use said heating with a vertical crimp configuration. Said heating may involve exposing the fibers of the tow band to steam, aerosolized compounds (e.g., plasticizers), liquids, heated fluids, direct heat sources, indirect heat sources, irradiation sources that causes additives in the fibers (e.g., nanoparticles) to produce heat, or any combination thereof.

[0057] Some embodiments of the present disclosure may include conditioning the crimped tow band. Conditioning may be used to achieve a crimped tow band having a residual acetone content of 0.5% or less w / w of the crimped tow band. Conditioning may be used to achieve a crimped tow band having a residual water content of 8% or less w / w of the crimped tow band. Conditioning may involve exposing the fibers of the crimped tow band to steam, aerosolized compounds (e.g., plasticizers), liquids, heated fluids, direct heat sources, indirect heat sources, irradiation sources that causes additives in the fibers (e.g., nanoparticles) to produce heat, or any combination thereof.

[0058] UCE is the amount of work required to uncrimp a fiber. UCE, as reported hereinafter, is sampled prior to baling, i.e., post-drying and pre-baling. UCE, as used herein, is measured as follows: using a warmed up (20 minutes before conventional calibration) Instron 3300 series Tensile Tester, tension load cell of sufficient range, top roller assembly, and appropriate grips capable of sufficient gripping force to prevent slippage), a preconditioned tow sample (preconditioned for 24 hours at 22° C ±2° C and Relative humidity at 60%±2%) of about 76 cm in length is looped over and spread evenly across the center of the top roller, pre-tensioned by gently pulling to 100 g±2 g (per readout display), and each end of the sample is clamped (at the highest available pressure, but not exceeding the manufacturers recommendations) in the lower grips to effect a 50 cm gauge length (gauge length measured from top of the robber grips), and then tested, until break, at a crosshead speed of 30 cm / minute. This test is repeated until three acceptable tests are obtained and theaverage of the three data points from these tests is reported. Energy (E) limits are between 0.220 kg and 10.0 kg. Displacement (D) has a preset point of 10.0 kg. UCE is calculated by the formula: UCE (gcm / cm)=(E*1000) / ((D*2)+500). Breaking strength can be calculated using the same test and the following equation BS = L (where L is the load at max load (kg)). In certain embodiments of the disclosure, UCE values (in gcm / cm) can range from 190 to 400 gcm / cm, e.g., 200 to 300 gcm / cm, e.g., approximately 290 gcm / cm. In certain embodiments of the disclosure, breaking strength can range from between 3.5 kg and 25 kg, e.g. 4 kg to 20 kg, 4.5 kg to 15 kg, or 5 kg to 12 kg.Cigarette Filter

[0059] A degradable cigarette filter generally includes a filter element (or filter plug) made of a bloomed cellulose acetate tow and a plug wrap surrounding the filter element. Cellulose acetate tow may be delivered to a filter producer as a bale. The tow is then opened or “bloomed” in rodmaking equipment in order to form the filter rod and eventual cigarette filter. Various properties are desirable for a cigarette filter, including firmness, pressure drop, pressure drop variability, openability, fly, and uncramping energy.

[0060] The disclosure will now be more particularly described with reference to the following non-limiting Examples.Examples

[0061] Example 1

[0062] Seven different types of tow were prepared and made into filter rods. The tow and process to make the tow and rods only differed in the cross-sectional shape and DPF (either 9 or 12). As shown in FIG. 2, the EPD was tested for each. The EPD was measured against the tow only weight (grams per 100 rods) for 1) tow having 12 dpf, 32,6000 total denier, and a Y-shaped cross section (target, comparative), 2) tow having 12 dpf, 32,00 total denier, and a Y-shaped cross section (comparative, closely matching the target), 3) tow having 12 dpf, 32,600 total denier, and a round-shaped cross section ((R), inventive), 4) tow having 9 dpf, 32,600 total denier, and a Y-shaped cross section (comparative), 5) tow having 9 dpf, 32,600 total denier, and a round-shaped cross section (inventive), 6) tow having 9 dpf, 32,600 total denier, and a pentagon-shaped cross section (inventive), and 7), tow having 12 dpf, 32,600 total denier, and a pentagon-shaped cross section (inventive).

[0063] As shown in FIG. 2, The comparative examples have a much greater difference in EPD from 9 to 12 DPF as compared to the inventive examples. The measured values for the tow and rods are reported in Table 1 below, with the “target” initial sample omitted. One additional sample 8) with a hexagon-shaped cross-sectional area, 12 dpf, and 32,000 total denier is also reported. As shown in FIG. 2 and as reported below in Table 1, the SSAI, slope of the line, and pressure drop were consistently lower for the inventive samples than for the comparative samples.

[0064] Example 2

[0065] To further illustrate the results of Example 1, FIG. 3 shows a scatterplot of pressure drop at 50 grams / 100 rods for four samples: 1) ) tow having 9 dpf, 32,000 total denier, and a Y-shaped cross section (comparative), 2) ) tow having 12 dpf, 32,000 total denier, and a Y-shaped cross section (comparative), 3) tow having 9 dpf, 32,000 total denier, and a round-shaped cross section (inventive), and 4) tow having 12 dpf, 32,000 total denier, and a round-shaped cross section (inventive). FIG. 3 shows the 35% decrease in pressure drop for the inventive tow as compared to the comparative tow.Embodiments

[0066] Embodiment 1: A cellulose acetate tow comprising cellulose acetate filaments, the tow having: a degree of substitution from 2.0 to 2.9; a denier per filament (dpf) from greater than 7.0 to 12.5; a total denier from 10,000 to 100,000; and wherein the cellulose acetate filaments have a cross-sectional shape with an SSAi of less than 1.70, where SSAi =measured perimeter (p) / perimeter of circle of equivalent area (p); and further wherein the cross-sectional shape is not Y-shaped.

[0067] Embodiment 2: The tow of Embodiment 1, wherein the DPF is from 8.0 to 12.5, from 9.0 to 12.5, or from 9.0 to 12.0.

[0068] Embodiment 3: The tow of Embodiment 1 or 2, wherein the total denier is from 15,000 to 100,000, from 15,000 to 80,000, from 20,000 to 60,000, or from 25,000 to 40,000.

[0069] Embodiment 4: The tow of any of the preceding Embodiments, wherein the cross-sectional shape is polygonal.

[0070] Embodiment 5: The tow of any of the preceding Embodiments, wherein the cross-sectional shape is a C-shaped.

[0071] Embodiment 6: The tow of any of the preceding Embodiments, wherein the cellulose acetate has a degree of substitution from 2.3 to 2.7.

[0072] Embodiment 7: The tow of any of the preceding Embodiments, wherein the SSAi is from 1.00 to 2.00, from 1.20 to 1.90, or from 1.25 to 1.80.

[0073] Embodiment 8: The tow of any of the preceding claims, wherein the tow has a round cross-sectional shape and an SSAi of less than 1.60.

[0074] Embodiment 9: The tow of any of the preceding Embodiments, wherein the tow has filaments with a hexagon cross-sectional shape and an SSAi of less than 1.80.

[0075] Embodiment 10: The tow of any of the preceding Embodiments, wherein the tow has filaments with a pentagon cross-sectional shape and an SSAi of less than 1.90.

[0076] Embodiment 11 : A tow bale comprising the tow according to any of the preceding Embodiments.

[0077] Embodiment 12: A debaled cellulose acetate tow formed from the tow according to any of Embodiments 1-10, and wherein the debaled cellulose acetate tow has a uniform uncrimping energy of less than 400 gcm / cm, preferably less than 300 gcm / cm.

[0078] Embodiment 13: A filter comprising the tow according to of any of Embodiments 1-10.

[0079] Embodiment 14: The filter of Embodiment 13, wherein the filter has an encapsulated pressure drop at a target weight of 50 grams / 100 rods of less than 200 mm water.

[0080] Embodiment 15: The filter of Embodiment 14, wherein the tow has a round cross-sectional shape and an encapsulated pressure drop at a target weight of 50 grams / 100 rods of less than 200 mm water.

[0081] Embodiment 16: The filter of Embodiment 15, wherein the tow has an SSAi of less than 1.90.

[0082] Embodiment 17: The filter of Embodiment 13, wherein the filter has filaments with a hexagon cross-sectional shape and an encapsulated pressure drop at a target weight of 50 grams / 100 rods of less than 200 mm water.

[0083] Embodiment 18: The filter of Embodiment 17, wherein the tow has filaments with an SSAi of less than 1.90.

[0084] Embodiment 19: The filter of Embodiment 13, wherein the tow has a pentagon cross-sectional shape and an encapsulated pressure drop at a target weight of 50 grams / 100 rods of less than 200 mm water.

[0085] Embodiment 20: The filter of Embodiment 19, wherein the tow has an SSAi of less than 1.90.

[0086] While the invention has been described in detail, modifications within the spirit and scope of the invention will be readily apparent to those of skill in the art. It should be understood that aspects of the invention and portions of various embodiments and various features recited above and / or in the appended claims may be combined or interchanged either in whole or in part. In the foregoing descriptions of the various embodiments, those embodiments which refer to another embodiment may be appropriately combined with other embodiments as will be appreciated by one of ordinary skill in the art. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention.

Claims

WHAT IS CLAIMED IS:

1. A cellulose acetate tow comprising cellulose acetate filaments, the tow having: a degree of substitution from 2.0 to 2.9;a denier per filament (dpf) from greater than 7.0 to 12.5;a total denier from 10,000 to 100,000; andwherein the cellulose acetate filaments have a cross-sectional shape with an SSAi of less than 2.00, where SSAi = measured perimeter (p) / perimeter of circle of equivalent area (p); andfurther wherein the cross-sectional shape is not Y-shaped.

2. The tow of claim 1, wherein the DPF is from 8.0 to 12.5, from 9.0 to 12.5, or from 9.0 to 12.0.

3. The tow of claim 1 or 2, wherein the total denier is from 15,000 to 100,000, from 15,000 to 80,000, from 20,000 to 60,000, or from 25,000 to 40,000.

4. The tow of any of the preceding claims, wherein the cross-sectional shape is polygonal or C-shaped.

5. The tow of any of the preceding claims, wherein the cellulose acetate has a degree of substitution from 2.3 to 2.7.

6. The tow of any of the preceding claims, wherein the SSAi is from 1.00 to 2.00, from 1.20 to 1.90, or from 1.25 to 1.80.

7. The tow of any of the preceding claims, wherein the tow has filaments with a round cross-sectional shape and an SSAi of less than 1.60 or wherein the tow has filaments with a hexagon cross-sectional shape and an SSAi of less than 1.80.

8. The tow of any of the preceding claims, wherein the tow has filaments with a pentagon cross-sectional shape and an SSAi of less than 1.90.

9. A tow bale comprising the tow according to any of the preceding claims.

10. A debaled cellulose acetate tow formed from the tow according to any of claims 1-10, and wherein the debaled cellulose acetate tow has a uniform uncrimping energy of less than 400 gcm / cm, preferably less than 300 gcm / cm.

11. A filter comprising the tow according to of any of claims 1-9.

12. The filter of claim 11, wherein the filter has an encapsulated pressure drop at a target weight of 50 grams / 100 rods of less than 200 mm water.

13. The filter of claim 12, wherein the tow has filaments with a round cross-sectional shape and an encapsulated pressure drop at a target weight of 50 grams / 100 rods of less than 200 mm water, optionally wherein the tow has an SSAi of less than 1.90.

14. The filter of claim 12, wherein the filter has filaments with a hexagon cross-sectional shape and an encapsulated pressure drop at a target weight of 50 grams / 100 rods of less than 200 mm water, optionally wherein the tow has an SSAi of less than 1.90.

15. The filter of claim 12, wherein the tow has filaments with a pentagon cross-sectional shape and an encapsulated pressure drop at a target weight of 50 grams / 100 rods of less than 200 mm water, optionally wherein the tow has an SSAi of less than 1.90.

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