RU2841855C2 - Lyocell material, a filter for a smoking article, a smoking article and a method of making same - Google Patents

Abstract

FIELD: tobacco smoke filters.

SUBSTANCE: disclosed is lyocell material, a filter for a smoking article and a smoking article containing such material, as well as a method of making same. Lyocell filter material for a smoking article comprises a lyocell multifilament that is crimped; and oil applied on lyocell multifilament. Oil contains a product of esterification of a fatty acid containing at least 16 carbon atoms and an aliphatic monoatomic alcohol and a product of esterification of sorbitan and a fatty acid containing at least 16 carbon atoms. Lyocell filter material for the smoking product contains oil in an amount of at least 2.0 wt. % per 100 wt. % of total weight of lyocell material.

EFFECT: lyocell material made according to the present invention, and a filter for a smoking article comprising such a material, replace conventional materials and filters from cellulose acetate, have excellent biodegradability and provide high manufacturability of filters and excellent physical properties of tobacco.

22 cl, 2 tbl, 14 ex

Description

Field of technology

[1] Cross-reference to related applications

[2] This application claims priority based on Korean Patent Application No. 10-2021-0190180 filed on December 28, 2021 and Korean Patent Application No. 10-2021-0190181 filed on December 28, 2021, and all contents disclosed in these Korean patent applications are incorporated into this description.

[3] Field of technology

[4] The present invention relates to a lyocell material, a filter and a smoking article containing such material, as well as a method for manufacturing them.

State of the art

[5] Until now, cellulose acetate fiber has been mainly used as a material for cigarette filters. As is known, cellulose acetate is a biodegradable material, however, cellulose acetate smoking product filters retain their original appearance for 1-2 years even after entering the soil, and it takes a long time for such filters to completely biodegrade. Considering the amount and toxicity of tobacco products thrown into the living environment and remaining in it, as well as tobacco products that are disposed of as waste and taken to landfills after being used for smoking, there is a need to further improve the biodegradability of smoking product filters. Accordingly, more environmentally friendly lyocell has recently been selected as a material to replace cellulose acetate.

[6] On the other hand, oiling can be performed to produce a tow for a filter of a smoking article. The moisture absorption rate of the lyocell tow treated with ordinary oil is about 10%, which is higher than that of the cellulose acetate tow, which is 5% (the moisture absorption rate is measured by a moisture analyzer combined with a scale capable of measuring moisture loss during drying and a drying oven in which the tow, the mass of which is measured in advance, is left at a temperature of about 105 °C, and then its mass is measured after stopping losing mass and compared with the original mass). Accordingly, the hardness of the filter containing the lyocell tow will be lower than that of the filter containing the cellulose acetate tow, and under actual use conditions, the decrease in hardness due to saliva will occur faster when using the filter containing the lyocell tow. For example, when smoking (depending on the user or the situation), the user may hold the cigarette in the mouth. In this case, saliva gets on the tip of the cigarette or the filter, as a result of which the rigidity (hardness) of the original filter for the smoking product decreases, which can be regarded by smokers as low quality. Therefore, cigarette manufacturers strive to produce products in which the filter does not deteriorate or has a low degree of deterioration and retains its original shape formed during the manufacture of the product, even after saliva gets on it.

[7] In this regard, there is a need to develop a filter material that can replace traditional cellulose acetate materials, has high rigidity and provides high quality or user satisfaction.

Disclosure

Technical problem of the invention

[8] One of the objectives of the present invention is to develop a lyocell material that will replace the commercially available cellulose acetate for filters for smoking articles.

[9] Another objective of the present invention is to develop a lyocell material for filters of smoking products, which is characterized by an environmentally friendly production process and high biodegradability during disposal.

[10] Another object of the present invention is to develop a lyocell material for filters of smoking articles, characterized by a slight change in rigidity upon penetration of moisture.

[11] Another object of the present invention is to provide a lyocell filter for a smoking article.

[12] Another object of the present invention is to provide a smoking article (e.g., a cigarette) comprising a lyocell filter.

[13] Another object of the present invention is to improve the manufacturability of the lyocell material, filters and smoking articles disclosed above.

[14] The above and other objects of the present invention can be solved by the present invention, which is described in detail below.

Technical solutions

[15] Embodiments of the present invention may provide lyocell material, filters, and smoking articles containing such material.

[16] Replacing the traditionally used cellulose acetate tow with lyocell has the above-mentioned difficulties. In other words, since the moisture absorption rate (or water content) of lyocell tow is generally higher than that of cellulose acetate tow, the rigidity is rapidly reduced by the action of saliva. This problem can be solved by treating the tow with a hydrophobic binder. However, the method of treating lyocell, which is highly hydrophilic, with a hydrophobic binder has limitations in increasing the rigidity of filters due to compatibility problems. In addition, poor compatibility may impair the processability of filters or smoking articles (e.g. cigarettes).

[17] In this aspect, the present inventor has treated the lyocell material with a special oil to overcome the hydrophilic properties of the lyocell surface, improve compatibility with the binder, and reduce the degree of stiffness reduction due to the needles (e.g., capable of providing a similar or equivalent level of stiffness compared to the cellulose acetate filter according to the prior art), thereby completing the disclosure of the present invention.

[18] In particular, in one embodiment of the present invention, there may be provided a lyocell material comprising: a lyocell multifilament that is crimped; and an oil supported on the lyocell multifilament, wherein the oil comprises (a) an esterification product of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol, and (b) an esterification product of sorbitan and a fatty acid containing at least 16 carbon atoms.

[19] In one embodiment of the present invention, there may be provided a lyocell material comprising: a lyocell multifilament that is crimped; and an oil applied to the lyocell multifilament, wherein the lyocell material has an immersion time in water of at least 6.0 seconds.

[20] In one embodiment of the present invention, a filter for a smoking article may be provided, comprising a lyocell material, wherein the lyocell material comprises: a lyocell multifilament that is crimped; and an oil supported on the lyocell multifilament, and the oil comprises (a) an esterification product of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol, and (b) an esterification product of sorbitan and a fatty acid containing at least 16 carbon atoms.

[21] In one embodiment of the present invention, a filter for a smoking article may be provided, in which the filter has a diameter retention rate before water injection, calculated according to Formula 1-1, expressing the degree of change in the rigidity of the filter for a smoking article, of at least 85%, and a diameter retention rate after water injection, calculated according to Formula 1-2, of at least 80%.

[22] In one embodiment of the present invention, a smoking article may be provided comprising a lyocell material or filter.

[23] In one embodiment of the present invention, a method for producing a lyocell material, as well as a filter and a smoking article, each of which comprises such material, may be provided.

[24] In one embodiment of the present invention, it is possible to obtain an oil capable of changing the hydrophilicity of the surface of a lyocell material to hydrophobicity and improving the degree of reduction in the hardness of a filter for a smoking article under the influence of moisture.

[25] As used herein, a "smoking article" is an article capable of generating an aerosol, such as a cigarette, cigar, etc. Smoking articles may contain a material or substrate for generating an aerosol. In some embodiments, smoking articles may contain solid materials based on tobacco raw materials, such as tobacco leaves, shredded tobacco, reconstituted tobacco, etc. In some embodiments, smoking materials may contain volatile substances.

[26] Unless otherwise explicitly stated in the description, in the case where the properties of lyocell materials, filters for a smoking article, as well as components or compositions associated therewith are affected by temperature, the temperature at which the properties are confirmed or measured may be room temperature. In this case, room temperature is understood to be a temperature that is not significantly lower or higher and is, for example, from 10°C to 35°C, for example from 15°C to 35°C, from 20°C to 30°C, or about 25°C.

[27] The present invention will now be described in more detail.

[28] One aspect of the present invention relates to a lyocell material. Although not particularly limited, the lyocell material can be used in filters for a smoking article.

[29] In some embodiments, the lyocell material may comprise: a lyocell multifilament that is crimped; and an oil supported on the lyocell multifilament. In some embodiments, the oil may comprise (a) an esterification product of a fatty acid having at least 16 carbon atoms and an aliphatic monohydric alcohol; and (b) an esterification product of sorbitan and a fatty acid having at least 16 carbon atoms. The oil may be supported on some or all of the monofilaments or multifilaments that comprise the lyocell material. In some embodiments, the oil may penetrate between the filaments.

[30] An oil comprising at least components (a) and (b) may have hydrophobic properties. Accordingly, the oil can eliminate problems associated with the hydrophilicity of the lyocell surface, its vulnerability to moisture and, as a result, a decrease in the rigidity of the filter. In some embodiments of the invention, the oil has excellent compatibility with the binder component disclosed below.

[31] In one embodiment of the present invention, the lyocell material may contain a predetermined amount of oil. In this regard, the amount of oil may mean the residual lubricant content (OPU) (wt%), which will be explained below. For example, the lyocell material may contain oil in an amount of at least 2.0 wt% based on 100 wt% of the total amount of the lyocell material. In some embodiments, the amount of oil may be 2.5 wt.%, at least 3.0 wt.%, at least, for example, at least 3.5 wt.%, at least 4.0 wt.%, at least 4.5 wt.%, at least 5.0 wt.%, at least 5.5 wt.%, at least 6.0 wt.%, at least 6.5 wt.%, at least 7.0 wt.%, at least 7.5 wt.%, at least 8.0 wt.%, at least 8.5 wt.%, at least 9.0 wt.%, or at least 9.5 wt.%. The upper limit may be, for example, 15.0 mass% or less, 14.5 mass% or less, 14.0 mass% or less, 13.5 mass% or less, 13.0 mass% or less, 12.5 mass% or less, 12.0 mass% or less, 11.5 mass% or less, 11.0 mass% or less, 10.5 mass% or less, 10 mass% or less, 9.5 mass% or less, 9.0 mass% or less, 8.5 mass% or less, 8.0 mass% or less, 7.5 mass% or less, 7.0 mass% or less, 6.5 mass% or less, 6.0 mass% or less, 5.5 mass% or less, 5.0 mass% or less, 4.5 mass% or less, 4.0 mass% or less, or 3.5 mass% or less.

[32] As a method for measuring the oil content (OPU), an extrusion method may be used, for example. For example, a sample (for example, 2 to 5 g, more specifically about 2.5 g) is taken (in this case, the mass of the taken sample is called the mass of the sample), and the sample is placed in a syringe-shaped container. The material of which the container is made is not particularly limited and may be stainless steel. Then, a solvent (for example, methanol) is added to the container to which the sample has been added (the amount of the solvent added may be 10 ml or less (for example, about 8 ml)). When adding the solvent to the sample, a dropping method may be used, and the dropping speed can be smoothly adjusted. Then, drops of the solvent introduced into the container as described above are allowed to fall onto a plate from one end of the syringe-shaped container. In this regard, the plate is preliminarily weighed (the measured mass is called the mass of plate A), and the plate is kept to remove droplets of solvent from the plate at a temperature of 120° to 130° (e.g., 125°) (i.e., until evaporation). The addition and dropping of the solvent are performed three times, and pressure (e.g., 10 kgf/ ^cm2 or less, 5 kgf/ ^cm2 , or 2-4 kgf/ ^cm2 ) is applied to the sample using a syringe-shaped container to compress the sample once. This allows the solvent and oil present in the sample to be sufficiently squeezed out. The sample was squeezed by applying pressure until the solvent stopped coming out. After that, the plate was kept in a drying oven for 5 to 10 minutes, and the mass of the plate with the sample on it (mass of plate B) was measured. Then, the amount of oil was calculated using the following formula:

[33] Formula

[34] Oil Percentage in Extrusion (OPU, % or wt.%)

[35] = {(mass of plate B - mass of plate A)/(mass of sample)} × 100

[36] In addition, the lyocell material used as a standard for determining the amount of oil may be a lyocell multifilament treated with at least an oil. For example, the lyocell material may be a lyocell multifilament that has undergone a first oiling (disclosed below), a lyocell multifilament that has undergone a first and second oiling (disclosed below), or a lyocell multifilament to which a binder, which will be disclosed below, is applied and has also undergone the oiling as disclosed above. In addition, the lyocell multifilament treated with oil and/or a binder as disclosed above may be a lyocell multifilament that has been crimped.

[37] With respect to the oil according to the present application, component (a) may be a compound capable of functioning as a lubricant or oil, and sufficiently harmless to the human body to be used in food products. Component (a) provides lubrication to the fibers fed to the twisting device. If the lubrication is insufficient, the lyocell may stick together and not come out of the twisting device, and if the lubrication is too high, the formation of curls may be difficult. The amount of component (a) can be adjusted taking into account these functions, as disclosed below.

[38] With respect to component (a), the type of fatty acid containing at least 16 carbon atoms included therein is essentially not limited. Fatty acids containing at least 16 carbon atoms whose esterification products are sufficiently harmless to the human body to be used in food can be used.

[39] For example, saturated fatty acids and/or unsaturated fatty acids can be used as fatty acids containing at least 16 carbon atoms.

[40] Saturated fatty acids include, for example, palmitic acid (hexadecanoic acid, _CH3 ( _CH2 ) _14COOH ), margaric acid (heptadecanoic acid, _CH3 ( _CH2 ) _15COOH ), stearic acid (octadecanoic acid, _CH3 ( _CH2 ) _16COOH ), nonadecylic acid (nonadecanoic acid, _CH3 ( _CH2 ) _17COOH ), or arachidic acid (eicosanoic acid, _CH3 ( _CH2 ) _18COOH ). However, the types of saturated fatty acids that can be used according to the present invention are not limited to these embodiments.

[41] Unsaturated fatty acids include, for example, palmitoleic acid ( _CH3 ( _CH2 ) _5CH =CH( _CH2 ) _7COOH ), oleic acid ( _CH3 ( _CH2 ) _7CH = _CH ( _CH2 ) _7COOH ), _linoleic acid ( _C18H32O2 ) or arachidonic acid ( _C20H32O2 ). However, the types of unsaturated fatty acids that can _be used according to the present invention are not _limited to this embodiment.

[42] The upper limit of the carbon number of a fatty acid containing at least 16 carbon atoms is essentially not limited and may be, for example, 40 or less, 36 or less, 32 or less, 28 or less, 24 or less, or 20 or less.

[43] As for component (a), the type of aliphatic monohydric alcohol included in its composition is also essentially unlimited. It is possible to use aliphatic monohydric alcohols whose esterification products are sufficiently harmless to the human body to be used in food products.

[44] For example, component (a) may be a saturated aliphatic alcohol or an unsaturated aliphatic alcohol, which may be in a linear or branched form.

[45] In one embodiment, the aliphatic monohydric alcohol may contain from 1 to 40 carbon atoms. In some embodiments, the carbon number of the aliphatic monohydric alcohol may be, for example, at least 4, at least 8, at least 12, at least 16, or at least 20.

[46] Examples of aliphatic monohydric alcohols include, in particular, methanol, ethanol, butanol, lauryl alcohol, isotridecanol or stearyl alcohol.

[47] In one embodiment of the present invention, component (a) may be an esterification product of isotridecanol and stearic acid (e.g., isotridecyl stearate). However, the types of component (a) that can be used according to the present invention are not limited to this embodiment.

[48] As will be disclosed below, the amount of component (a) included in the oil can be adjusted taking into account the function of the oil or the function of component (a).

[49] Component (b), i.e. the esterification product of sorbitan and a fatty acid containing at least 16 carbon atoms, is a compound capable of functioning as a kind of emulsifier and is sufficiently harmless to the human body to be used in foodstuffs.

[50] Since the component (b) has both hydrophilic and hydrophobic properties due to the polyhydric alcohol (i.e., sorbitan), the component (a) providing fiber lubrication is capable of being well dispersed in water, which will be explained later. In addition, the components (a) and (b) used together not only increase the dispersibility of the oil, as explained above, but also lower the melting point of the oil, thereby ensuring its processability and stability. The amount of the component (b) can be adjusted taking into account these functions, as explained later.

[51] With respect to component (b), the type of fatty acid containing at least 16 carbon atoms included therein is essentially not limited. Fatty acids containing at least 16 carbon atoms whose esterification products are sufficiently harmless to the human body to be used in food can be used.

[52] For example, saturated fatty acids and/or unsaturated fatty acids can be used as fatty acids containing at least 16 carbon atoms.

[53] Saturated fatty acids include, for example, palmitic acid (hexadecanoic acid, _CH3 ( _CH2 ) _14COOH ), margaric acid (heptadecanoic acid, _CH3 ( _CH2 ) _15COOH ), stearic acid (octadecanoic acid, _CH3 ( _CH2 ) _16COOH ), nonadecylic acid (nonadecanoic acid, _CH3 ( _CH2 ) _17COOH ), or arachidic acid (eicosanoic acid, _CH3 ( _CH2 ) _18COOH ). However, the types of saturated fatty acids that can be used according to the present invention are not limited to this embodiment.

[54] Unsaturated fatty acids are, for example, palmitoleic acid ( _CH3 ( _CH2 ) _5CH =CH( _CH2 ) _7COOH ), oleic acid ( _CH3 ( _CH2 ) _7CH =CH( _CH2 ) _7COOH ), _linoleic acid ( _C18H32O2 ) or arachidonic acid ( _C20H32O2 ). However, the types _of saturated fatty acids that can _be used according to the present invention are not _limited to this embodiment.

[55] The upper limit of the carbon number of a fatty acid containing at least 16 carbon atoms is essentially not limited and may be, for example, 40 or less, 36 or less, 32 or less, 28 or less, 24 or less, or 20 or less.

[56] In one embodiment of the present invention, component (b) may be an esterification product of sorbitan and oleic acid (e.g., sorbitan monooleate). However, the types of component (b) that can be used according to the present invention are not limited to this embodiment.

[57] The amount of component (b) can be adjusted taking into account the function of component (b) and the function of oil as disclosed above.

[58] In one embodiment of the invention, the oil may contain from 20 to 60 weight parts (b) of the esterification product of sorbitan and a fatty acid containing at least 16 carbon atoms based on 100 weight parts (a) of the esterification product of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol.

[59] In some embodiments, the oil of the present invention may comprise at least 25 parts by weight, at least 30 parts by weight, at least 35 parts by weight, at least 40 parts by weight, at least 45 parts by weight, or at least 50 parts by weight of component (b), based on 100 parts by weight of component (a). The upper limit of the amount of component (b) per 100 parts by weight of component (a) may be, for example, 55 parts by weight or less, 50 parts by weight or less, 45 parts by weight or less, 40 parts by weight or less, 35 parts by weight or less, 30 parts by weight or less, or 25 parts by weight or less. Within these values, the surface of the oiled lyocell multifilament or oiled lyocell tow may have hydrophobic properties and, as a result, excessive reduction in filter rigidity due to moisture penetration (e.g. saliva) may be prevented.

[60] In one embodiment of the invention, the oil may further comprise as component (c) an alkylene oxide adduct with respect to component (b). Component (c) may act as an emulsifier. The compound may also be selected from among compounds that are sufficiently harmless to the human body to be used in food products.

[61] With respect to component (c), the type of alkylene oxide is not particularly limited, and, for example, the alkylene oxide may contain from 2 to 4 carbon atoms. In particular, with respect to component (c), ethylene oxide, propylene oxide and/or butylene oxide may be used, but other embodiments are also possible.

[62] The number of moles of alkylene oxide added is not limited in essence. For example, the number of moles of alkylene oxide added may be from 1 to 100, from 5 to 80, from 10 to 60, or from 15 to 40.

[63] In one embodiment of the present invention, component (c) may be an esterification product of a PEO sorbitan adduct and oleic acid (e.g., polyoxyethylene sorbitan monooleate). However, the types of component (c) that can be used according to the present invention are not limited to this embodiment.

[64] Component (c) improves the processability in the process of manufacturing filters for smoking articles: suppression of static electricity generation in lyocell threads; prevention of cuts due to static electricity generation. In particular, moisture is adsorbed on the fiber surface by alkylene oxide compounds, which leads to suppression of static electricity generation. In addition, component (c) promotes effective dispersion of oil in water.

[65] The amount of component (c) can be adjusted taking into account the function of component (c) and the function of oil as disclosed above.

[66] In one embodiment of the invention, the oil may contain from 10 to 50 parts by weight (c) of an alkylene oxide adduct relative to the esterification product (b) based on 100 parts by weight (a) of the esterification product of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol.

[67] In some embodiments, the oil of the present invention may comprise at least 15 parts by weight, at least 20 parts by weight, at least 25 parts by weight, at least 30 parts by weight, at least 35 parts by weight, at least 40 parts by weight, or at least 45 parts by weight of component (c) based on 100 parts by weight of component (a). The upper limit of the amount of component (c) based on 100 parts by weight of component (a) may be, for example, 45 parts by weight or less, 40 parts by weight or less, 35 parts by weight or less, 30 parts by weight or less, 25 parts by weight or less, 20 parts by weight or less, or 15 parts by weight or less.

[68] In one embodiment of the invention, the oil may comprise (b) an esterification product of sorbitan and a fatty acid containing at least 16 carbon atoms in excess of (c) an alkylene oxide adduct relative to the esterification product of (b).

[69] In one embodiment, the oil may comprise (a) from 40 to 80 wt.% of the esterification product of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol, based on 100 wt.% of the total weight of the oil. In some embodiments, based on 100 wt.% of the total weight of the oil, the amount of component (a) may be at least 45 wt.%, at least 50 wt.%, at least 55 wt.%, at least 60 wt.%, at least 65 wt.%, at least 70 wt.%, or at least 75 wt.%. The upper limit of the amount of component (a) may be, for example, 75 mass% or less, 70 mass% or less, 65 mass% or less, 60 mass% or less, 55 mass% or less, 50 mass% or less, or 45 mass% or less.

[70] In one embodiment of the invention, the oil may contain component (a) in the largest excess amount among components (a)-(c).

[71] In one embodiment of the invention, the oil may comprise from 15 to 55 wt.% (b) of the esterification product of sorbitan and a fatty acid containing at least 16 carbon atoms, based on 100 wt.% of the total weight of the oil. In some embodiments, based on 100 wt.% of the total weight of the oil, the amount of component (b) may be at least 20 wt.%, at least 25 wt.%, at least 30 wt.%, at least 35 wt.%, at least 40 wt.%, at least 45 wt.%, or at least 50 wt.%. The upper limit of the amount of component (b) may be, for example, 50 wt.% or less, 45 wt.% or less, 40 wt.% or less, 35 wt.% or less, 30 wt.% or less, or 25 wt.% or less.

[72] In one embodiment of the invention, the oil may comprise from 10 to 30 wt.% of component (c), i.e., an alkylene oxide adduct relative to component (b), based on 100 wt.% of the total weight of the oil. In some embodiments, based on 100 wt.% of the total weight of the oil, the amount of component (c) may be at least 15 wt.%, at least 20 wt.%, or at least 25 wt.%. The upper limit of the amount of component (c) may be, for example, 25 wt.% or less, 20 wt.% or less, or 15 wt.% or less.

[73] In one embodiment, based on 100% by weight of the total weight of the oil, the oil may comprise (b) an esterification product of sorbitan and a fatty acid containing at least 16 carbon atoms; and (c) an alkylene oxide adduct relative to component (b) in an amount of at least 15% by weight. In some embodiments, based on 100% by weight of the total weight of the oil, the sum of the amount of component (b) and the amount of component (c) may be 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, or at least 50% by weight. The upper limit of the sum of the amount of component (b) and the amount of component (c) may be, for example, 55 mass% or less, 50 mass% or less, 45 mass% or less, 40 mass% or less, 35 mass% or less, 30 mass% or less, or 25 mass% or less.

[74] In one embodiment of the invention, the oil may further comprise (d) water. As will be disclosed below, water in small amounts promotes emulsification.

[75] The amount of water is not limited in essence, but may be the remaining amount excluding the total amount of the components (a) to (c), based on 100% by mass of the total weight of the oil. The amount of water in the oil (i.e. the remaining amount excluding the total amount of the remaining components other than water) may be, for example, 10% by mass or less, 9% by mass or less, 8% by mass or less, 7% by mass or less, 6% by mass. Hereinafter, it may be 5% by mass or less, 4% by mass or less, 3% by mass or less, 2% by mass or less, or 1% by mass or less. The lower limit of the water content in the oil may be, for example, at least 0.1% by mass, at least 0.5% by mass, or at least 1% by mass.

[76] The lyocell material according to the present invention may be a crimped tow with a fineness suitable for producing a filter for a smoking article and ensuring its functionality. For example, the overall fineness of the tow depends on the number of threads that can be inserted into the filter wrapper. If the overall fineness is too small, it may not be possible to place a sufficient number of threads in the filter wrapper, which will lead to a decrease in the draw resistance. If the overall fineness is too high, the amount of filler in the filter wrapper becomes too large, which leads to a rupture of the filter wrapper, or it becomes difficult to control the amount of filler to achieve the required draw resistance for the filter.

[77] In one embodiment of the invention, the fineness of a single thread included in the lyocell multifilament may be from 1.5 to 8.0 denier. In this case, the fineness of the thread is understood to be the fineness of a single monofilament separated from the multifilament.

[78] In particular, the fineness of one thread may be, for example, 7.5 denier or less, 7.0 denier or less, 6.5 denier or less, 6.0 denier or less, 5.5 denier or less, 5.0 denier or less, 4.5 denier or less, 3.5 denier or less, or 3.0 denier or less. The lower limit of the fineness of one thread may be, for example, at least 2.0 denier, such as at least 2.5 denier, at least 3.0 denier, at least 3.5 denier, at least 4.0 denier, at least 4.5 denier, at least 5.0 denier, at least 5.5 denier, or at least 6.0 denier. In these ranges, stable physical properties (e.g. rigidity or resistance to draw, etc.) and processability of filters for a smoking article can be achieved.

[79] In one embodiment of the invention, the lyocell multifilament that is crimped may be a crimped tow with an overall fineness of from 15,000 to 45,000 denier. In one embodiment of the invention, the lower limit of the overall fineness may be, for example, at least 16,000, at least 16,500, at least 17,000, at least 17,500, at least 18,000, at least 18,500, at least 19,000, at least 19,500, at least 20,000, at least 20,500, at least 21,000, at least 21,500, at least 22,000, at least 22,500, at least 23,000, at least 23,500, at least 24,000, at least 24,500, at least 25,000, at least 25,500, at least 26 000, at least 26,500, at least 27,000, at least 27,500, at least 28,000, at least 28,500, at least 29,000, at least 29,500, at least 30,000, at least 30,500, at least 31,000, at least 31,500, at least 32,000, at least 32,500, at least 33,000, at least 33,500, at least 34,000, at least 34,500, at least 35,000, at least 35,500, at least 36,000, at least 36,500, at least 37 000, at least 37,500, at least 38,000, at least 38,500, at least 39,000, at least 39,500, at least 40,000, at least 40,500, at least 41,000, at least 41,500, at least 42,000, at least 42,500, at least 43,000, at least 43,500, or at least 44,000. In one embodiment of the invention, the upper limit of the overall fineness can be, for example, 44,500 or less, 44,000 or less, 43,500 or less, 43,000 or less, 42,500 or less, 42,000 or less, 41,500 or less, 41,000 or less, 40,500 or less, 40,000 or less, 39,500 or less, 39,000 or less, 38,500 or less, 38,000 or less, 37,500 or less, 37,000 or less, 36,500 or less, 36,000 or less, 35,500 or less, 35,000 or less, 34,500 or less, 34,000 or less, 33,500 or less, 33,000 or less, 32,500 or less, 32,000 or less, 31,500 or less, 31,000 or less, 30,500 or less, 30,000 or less, 29,500 or less, 29 000 or less, 28,500 or less, 28,000 or less, 27,500 or less, 27,000 or less, 26,500 or less, 26,000 or less, 25,500 or less, 25,000 or less, 24,500 or less, 24,000 or less, 23,500 or less, 23,000 or less, 22,500 or less, 22,000 or less, 21,500 or less, 21,000 or less, 20,500 or less, 20,000 or less, 19,500 or less, 19,000 or less, 18,500 or less, 18,000 or less, 17,500 or less, 17,000 or less less than, 16,500 or less, 16,000 or less, or 15,500 or less. If the overall fineness of the tow is outside these ranges, the manufacturing processability of filters for smoking articles will not be very high (continuous cutting process is impossible), and the amount of tow placed in the filter wrapper when manufacturing filters for smoking articles will be insufficient or excessive, which will make it difficult to obtain sufficient filter properties (such as rigidity or resistance to draw).

[80] The method for measuring the degree of fineness is not limited in essence, but, for example, the tow to be measured is taken as a sample 2 m long, kept in a room with a constant temperature of 20°C and humidity of 65% for 24 hours, and stabilized. One end of the stabilized tow is fixed, and a load weighing 2 kg is attached to the other end. The tow is kept (stabilized) in a stretched state under the action of a load for 5 seconds, after which it is cut to 90 cm to obtain a sample, and the mass of the sample (total fineness) is measured. The fineness is calculated in terms of denier: measured mass × 10,000. The fineness of one fiber is calculated by dividing the total fineness by the number of strands in the thread.

[81] The overall fineness of the tow, as disclosed above, can be determined depending on the fineness of one thread and the number of twists. According to the method proposed by the present invention, since the fineness of one fiber and the number of twists are controlled by the method disclosed above, the overall fineness of the tow suitable for producing filters for a smoking article and its functionality can be ensured.

[82] In one embodiment of the invention, the crimped lyocell multifilament may comprise from 20 to 50 twists per inch. For example, the number of twists may be at least 25 twists per inch, at least 30 twists per inch, at least 35 twists per inch, at least 40 twists per inch, or at least 45 twists per inch, and the upper limit may be, for example, 45 twists per inch or less, 40 twists per inch or less, 35 twists per inch or less, 30 twists per inch or less, or 25 twists per inch or less. The number of twists and their uniformity can be adjusted depending on the pressure and temperature conditions associated with the twisting operation, which will be disclosed below.

[83] Although there are no specific limitations, the number of crimps can be measured, for example, according to KS K 0326. Specifically, a tow specimen of 20 strands with intact crimps was prepared to which a pre-prepared sheet of sanded paper was attached (at intervals of 25 mm) using 4% - 5% celluloid amyl acetate adhesive in such a way that each strand of the individual fibre was stretched by 25 ± 5% and then left until the adhesive dried. In addition, a crimp tester was used for this specimen, which applied an initial load equivalent to 1.96/1,000 cN (= 2 mgf) per 1 De for each strand, and the number of crimps per 25 mm was counted. In this regard, the number of crimps can be expressed as the upper and lower limits of the number of crimps measured for 20 strands. Alternatively, the number of twists may be expressed as the arithmetic mean of the number of twists measured for 20 strands.

[84] Although there are no particular limitations, the lyocell material prepared by the above-disclosed method can be used in filters for a smoking article.

[85] In one embodiment, the lyocell material may further comprise a binder. The binder may be present, for example, on the surface of the crimped lyocell multifilament or between the crimps of the lyocell multifilament (or monofilaments). The binder may increase the rigidity of the filters for a smoking article made from the tow, preventing the filters from being cut off during the manufacture of filters or smoking articles (e.g., cigarettes).

[86] The type of binder that can be used in the present invention is not particularly limited, and any known binder can be used as long as it does not violate the essence of the present invention. For example, a binder that has sufficient compatibility with the oil used in the present invention, increases the rigidity of the filter, and provides high binding force can be used.

[87] In one embodiment of the invention, the binder may be a polyester-based binder, a cellulose-based binder and/or a vinyl-based binder.

[88] Although there are no particular limitations, a polyester binder containing alkylene and/or arylene and/or heteroarylene, each of which contains from 5 to 12 carbon atoms, can be used.

[89] Cellulose-based binders include, for example, hydroxypropyl methylcellulose (HPMC), ethylcellulose (EC) and/or methylcellulose (MC), carboxymethylcellulose (CMC), etc., but are not limited to these options.

[90] Vinyl binders are, for example, polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA) and/or ethylene vinyl acetate (EVAc), but other variants are also possible.

[91] The method of applying (coating) a binder to a lyocell material will be disclosed below.

[92] In one embodiment of the invention, the lyocell material may be a lyocell material (a crimped rope) that is immersed in water for at least 6.0 seconds. In this case, the immersion time is understood to be the time the lyocell material sinks to the bottom of a water-filled container after adding the lyocell material to the container (e.g., a glass) (for specific measurement methods, see the examples disclosed below).

[93] In one embodiment of the present invention, the length of the tow used in measuring the immersion time (e.g., the length of the longest dimension of the tow shape) may be, for example, 10 cm or less, 9 cm or less, 8 cm or less, 7 cm or less, 6 cm or less, or 5 cm or less, and the lower limit may be at least 1 cm, at least 2 cm, at least 3 cm, at least 4 cm, or at least 5 cm. In this case, an error in the size (length) of the cut within ±1 cm, ±0.5 cm, or ±0.1 cm is possible.

[94] In one embodiment of the present invention, for measuring the immersion time, the height of water poured into the container may be from 12 to 13 cm or about 12.5 cm. In this case, the error in the height may be ±1 cm, ±0.5 cm or ±0.1 cm.

[95] The shorter the immersion time in water, the higher the hydrophilicity of the material, and the longer the immersion time in water, the higher the hydrophobicity of the material. Similar to the experiments disclosed below, in the present invention, by using a predetermined amount of oil containing predetermined components, a relatively long immersion time can be imparted to the lyocell material. In other words, the lyocell material according to the present invention can have a hydrophobic surface due to the oil coating.

[96] The immersion time can be adjusted depending on the amount (mass %) of oil in the material. For example, the immersion time can be at least 6.5 seconds, at least 7.0 seconds, at least 7.5 seconds, at least 8.0 seconds, at least 8.5 seconds, at least 9.0 seconds, at least 9.5 seconds, or at least 10 seconds, as well as 15 seconds or less, 14 seconds or less, 13 seconds or less, 12 seconds or less, 11 seconds or less, 10 seconds or less.

[97] As discussed below, these settling time characteristics can also be expressed as settling velocity (cm/sec) versus time and water level discussed above.

[98] In another embodiment of the present invention, a lyocell material is provided that has hydrophobic properties. For example, the lyocell material may have certain water immersion characteristics.

[99] In one embodiment of the invention, the lyocell material may be a lyocell material (a crimped rope) that is immersed in water for at least 6.0 seconds. In this case, the immersion time is understood to be the time the lyocell material sinks to the bottom of a water-filled container after adding the lyocell material to the container (e.g., a glass) (for specific measurement methods, see the examples disclosed below).

[100] In one embodiment of the present invention, the length of the tow used in measuring the immersion time (e.g., the length of the longest dimension of the tow shape) may be, for example, 10 cm or less, 9 cm or less, 8 cm or less, 7 cm or less, 6 cm or less, or 5 cm or less, and the lower limit may be at least 1 cm, at least 2 cm, at least 3 cm, at least 4 cm, or at least 5 cm. In this case, an error in the size (length) of the cut within ±1 cm, ±0.5 cm, or ±0.1 cm is possible.

[101] In one embodiment of the present invention, for measuring the immersion time, the height of water poured into the container may be from 12 to 13 cm or about 12.5 cm. In this case, the error in the height may be ±1 cm, ±0.5 cm or ±0.1 cm.

[102] The shorter the immersion time in water, the higher the hydrophilicity of the material, and the longer the immersion time in water, the higher the hydrophobicity of the material. Similar to the experiments disclosed below, in the present invention, by using the oil disclosed above, a relatively long immersion time of the lyocell material can be achieved. In other words, the lyocell material according to the present invention can have a hydrophobic surface due to the oil coating.

[103] The immersion time can be adjusted depending on the amount (mass %) of oil in the material. For example, the immersion time can be at least 6.5 seconds, at least 7.0 seconds, at least 7.5 seconds, at least 8.0 seconds, at least 8.5 seconds, at least 9.0 seconds, at least 9.5 seconds, or at least 10 seconds, as well as 15 seconds or less, 14 seconds or less, 13 seconds or less, 12 seconds or less, 11 seconds or less, 10 seconds or less.

[104] In one embodiment, the settling characteristics may also be expressed as a settling velocity. For example, the lyocell material of the present invention may have a settling velocity in water of 2.1 cm/sec or less. Specific examples of these velocities may be calculated based on the time and water level disclosed above.

[105] In one embodiment of the invention, the lyocell material comprises: a lyocell multifilament that is crimped; and an oil applied to the lyocell multifilament. The descriptions of the lyocell thread, the oil, and the material containing them are similar to those disclosed above and will therefore be omitted.

[106] Although there are no particular limitations, lyocell material with deposition characteristics corresponding to those disclosed above can be used in filters for a smoking article.

[107] One embodiment of the present invention relates to a method for producing a lyocell material. This method makes it possible to produce a lyocell material for a filter for a smoking article.

[108] The lyocell material to which the hydrophobic oil is applied can retard the instantaneous absorption of moisture when manufactured as a filter for a smoking article. In addition, since the oil according to the present invention is well compatible with the binder, physical properties (e.g., rigidity, resistance to draw, etc.) required for various smoking articles (e.g., cigarettes) can be ensured.

[109] In particular, a method for producing a lyocell material comprises oiling a lyocell multifilament and crimping the lyocell multifilament. In some embodiments, the oil may comprise at least (a) an esterification product of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol; and (b) an esterification product of sorbitan and a fatty acid containing at least 16 carbon atoms.

[110] The oiling can be carried out, for example, by spraying the oil of the above-disclosed composition onto the lyocell yarn or by dipping the lyocell yarn into the oil. The method according to the present invention comprising the oiling step can be carried out in such a way that the amount of oil (for example, OPU (mass %)) in the lyocell material corresponds to the specified ranges disclosed below.

[111] Furthermore, crimping can be achieved, for example, by applying steam and/or pressure to the lyocell multifilament.

[112] The description of the oil components is similar to that disclosed above. Therefore, the corresponding description will be omitted.

[113] A method for producing a lyocell material in one embodiment of the present invention, comprising an oiling process and a crimping step, will be described in more detail below. The method according to the present invention can be carried out using one or more of the processes described below.

[114] Spinning process of lyocell dope (a)

[115] This process is a spinning process of a lyocell dope containing cellulose (or cellulose pulp) and N-methylmorpholine oxide (NMMO).

[116] Commercially available cellulose acetate filters are considered to be the main cause of microplastic formation. However, since the amine oxide solvent used in the production of lyocell fibers is recyclable and biodegradable even when disposed of, lyocell materials do not emit any pollutants during the production process. In addition, lyocell tow is a biodegradable material and can be decomposed within a relatively short period of time, making lyocell a more environmentally friendly material than cellulose acetate.

[117] In one embodiment of the invention, the amount of cellulose in the spinning solution may be from 5 to 15 wt.% per 100 wt.% of the total weight of the material. If the amount of cellulose is too small, it is difficult to obtain the desired characteristics of the lyocell fiber, and if the amount exceeds the range, it is difficult to ensure dissolution in the solvent. In this regard, the amount of cellulose in the spinning solution may be at least 6 wt.%, at least 7 wt.%, at least 8 wt.%, at least 9 wt.%, or at least 10 wt.%, and the upper limit may be, for example, 14 wt.% or less, 13 wt.% or less, 12 wt.% or less, 11 wt.% or less, 10 wt.% or less, or 9 wt.% or less.

[118] In one embodiment of the invention, the spinning solution may comprise an aqueous solution of N-methylmorpholine-N-oxide (NMMO). The aqueous solution may comprise, for example, from 80 to 95 wt.% N-methylmorpholine-N-oxide and from 5 to 20 wt.% water, taking into account the degree of dissolution of the cellulose and the process temperature.

[119] In one embodiment of the invention, the cellulose or cellulose pulp may contain alpha-cellulose in an amount of from 85 to 97% by weight, based on 100% by weight of the total cellulose.

[120] Furthermore, in one embodiment of the present invention, the degree of polymerization (DPw) of cellulose may be from 600 to 1700.

[121] In the spinning process, the choice of the shape of the spinning mechanism for discharging the spinning solution is essentially unlimited. For example, a toroidal spinning mechanism can be used.

[122] The temperature of the nozzle of the spinning mechanism, for example the spinning temperature of such a mechanism, can be appropriately selected by a person skilled in the art. Considering that the viscosity of the spinning solution depends on the spinning temperature and can make unloading difficult, the spinning temperature can be, for example, from 100° to 120° or from 100° to 110°.

[123] In one embodiment of the invention, the spinning process of the spinning solution may be carried out under controlled conditions, in which the fineness of a single filament may be from 1.5 to 8.0 denier. For example, one or more spinning conditions, namely the amount of discharge and/or the spinning speed of the spinning solution, may be suitably adjusted so that the fineness of the filament forming the lyocell material is from 1.5 to 8.0 denier. In this case, the fineness of the filament is understood to be the fineness of a single monofilament separated from the multifilament.

[124] In particular, the fineness of one thread can be, for example, 7.5 denier or less, 7.0 denier or less, 6.5 denier or less, 6.0 denier or less, 5.5 denier or less, 5.0 denier or less, or 4.5 denier or less. The lower limit of the fineness of one thread can be, for example, at least 2.0 denier, such as at least 2.5 denier, at least 3.0 denier, at least 3.5 denier, at least 4.0 denier, at least 4.5 denier, at least 5.0 denier, at least 5.5 denier or at least 6.0 denier. In these ranges, stable draw resistance and processability of filters for a smoking article can be obtained.

[125] The spinning solution leaving the spinning mechanism may be subjected to the coagulation process described below.

[126] Coagulation and multifilament formation (b)

[127] At this stage, coagulation of the lyocell spinning solution occurs and lyocell multifilaments can be obtained.

[128] Coagulation may be achieved by contacting the spinning solution with air and/or a coagulating liquid.

[129] In one embodiment of the invention, the coagulation comprises: a first coagulation process comprising supplying cooling air to the spun lyocell solution; and a second coagulation process comprising coagulating the first coagulated spinning solution by adding it to a coagulating liquid.

[130] In the coagulation method, the lyocell spinning solution discharged from the spinning mechanism is first coagulated in the space (air gap portion) between the spinning mechanism and the coagulation tank. For example, cooling air can be supplied to this air gap portion from an air cooling portion located inside the spinning mechanism in a direction from the center to the periphery of the spinning mechanism. In addition, the first coagulation can be achieved by an air cooling method or other methods known in the art.

[131] In one embodiment of the invention, the upper limit of the temperature of the cooling air used for the first coagulation may be, for example, 15°C or lower. In some embodiments of the invention, the cooling air may be air with a temperature of 14°C or lower, 13°C or lower, 12°C or lower, 11°C or lower, or 10°C or lower. If the temperature exceeds these limits, the coagulation of the spinning solution may be insufficient and the spinning processability may be low.

[132] The lower limit of the cooling air may be determined taking into account the spinning workability and/or the uniformity of the cross-section of the thread. For example, if the temperature of the cooling air is below 4°C, the surface of the spinning mechanism is cooled, the surface of the thread becomes uneven, and the spinning workability also deteriorates. In this aspect, the cooling air may have a temperature of at least 5°C, at least 6°C, at least 7°C, at least 8°C, or at least 9°C.

[133] The degree of supply of cooling air can be adjusted taking into account sufficient coagulation, spinning processability and the effect on the physical properties of the thread. For example, the supply to the spinning solution can be implemented with an air flow rate of 70 ^Nm3 /h to 300 ^Nm3 /h. In some embodiments of the invention, the air flow rate can be at least 100 ^Nm3 /h or at least 150 ^Nm3 /h, and the upper limit of the air flow rate can be, for example, 250 ^Nm3 /h or less or 200 ^Nm3 /h or less.

[134] After the first coagulation, as disclosed above, the cooled spinning solution can be fed into a coagulation tank or bath containing a coagulating liquid (second coagulation). For proper coagulation, the temperature of the coagulating liquid can be, for example, 30 °C and below or 25 °C and below. In some embodiments of the invention, the temperature of the coagulating liquid can be at least 10 °C, at least 15 °C, or at least 20 °C. Maintaining such temperatures allows maintaining the coagulation rate at the proper level.

[135] The choice of the type of coagulating liquid for the second coagulation, as disclosed above, is essentially not limited. For example, the coagulating liquid may comprise water and/or N-methylmorpholine-N-oxide (NMMO).

[136] Although there are no limitations as to the substance, if the coagulating liquid contains water and NMMO, the water content of the coagulating liquid may be from 60 to 90% by weight, and the NMMO content of this liquid may be from 10 to 40% by weight. Alternatively, the coagulating liquid may contain from 70 to 80% by weight of water and from 20 to 30% by weight of NMMO. The concentration of the coagulating liquid may be monitored and maintained during the production process using a sensor or similar device.

[137] Flushing process (c)

[138] If necessary, the multifilament can be washed after the coagulation and multifilament production processes described above. Washing allows the removal of NMMO and/or other impurities remaining in the thread.

[139] The choice of washing method is essentially unlimited. For example, washing can be carried out by introducing coagulated lyocell multifilaments into a washing tank using a pull roller. Alternatively, the washing liquid can be sprayed during the transition to the next process using a pull roller.

[140] The choice of components of the washing liquid is essentially unlimited. For example, the washing liquid may contain water, as well as other known additives.

[141] In addition, considering the possibility of reuse after washing, the washing liquid can be used by setting the temperature to 100°C or lower.

[142] Oiling process (d)

[143] This process is the application of oil containing the above-disclosed components to the surface of the thread. Oiling reduces the friction acting on the thread and forms quality crimps in the crimping process disclosed below. As will be disclosed later, when oiling is performed two or more times, the oiling may be called first oiling and second oiling depending on the order in which the process is performed.

[144] Although there are no particular limitations, oiling may be accomplished by immersing the multifilament in an oil-filled bath so that the multifilament is completely immersed in oil. Alternatively, oiling may be accomplished by spraying an oil solution during transfer to the next process using a pull roller.

[145] In order to ensure a constant amount of oil applied to the multifilament, after the oiling described above, an additional process of squeezing oil onto the surface of the multifilament can be performed using a roller located before and/or after the oiling station.

[146] In one embodiment of the invention, the oiling may be performed such that the amount of oil (OPU: residual lubricant content (wt %)) corresponds to at least 2.0 wt % based on 100 wt % of the multifilament treated with at least oil. The multifilament treated with at least oil may be, for example, a lyocell multifilament that has undergone a first oiling (disclosed below), a lyocell multifilament that has undergone a first and second oiling (disclosed below), or a lyocell multifilament to which a binder, which will be disclosed below, is applied and has also undergone the oiling as disclosed above. Furthermore, the lyocell multifilament treated with oil and/or a binder as disclosed above may be a lyocell multifilament that has been crimped.

[147] In particular, the amount of oil in the multifilament treated with at least the oil can be at least 2.5 wt.%, at least 3.0 wt.%, at least 3.5 wt.%, at least 4.0 wt.%, at least 4.5 wt.%, at least 5.0 wt.%, at least 5.5 wt.%, at least 6.0 wt.%, at least 6.5 wt.%, at least 7.0 wt.%, at least 7.5 wt.%, at least 8.0 wt.%, at least 8.5 wt.%, at least 9.0 wt.% or at least 9.5 wt.%. The upper limit may be, for example, 15.0 mass% or less, 14.5 mass% or less, 14.0 mass% or less, 13.5 mass% or less, 13.0 mass% or less, 12.5 mass% or less, 12.0 mass% or less, 11.5 mass% or less, 11.0 mass% or less, 10.5 mass% or less, 10 mass% or less, 9.5 mass% or less, 9.0 mass% or less, 8.5 mass% or less, 8.0 mass% or less, 7.5 mass% or less, 7.0 mass% or less, 6.5 mass% or less, 6.0 mass% or less, 5.5 mass% or less, 5.0 mass% or less, 4.5 mass% or less, 4.0 % by weight or less, or 3.5% by weight or less. In this regard, the amount may refer to the dry weight after evaporation of a solvent (e.g. water) or a liquid component that may be part of the oil.

[148] When the oil of the above-described composition is processed in these amount ranges, the hydrophilic characteristics of the lyocell material can be compensated for, and, as disclosed below, excessive decrease in the rigidity of the lyocell filter due to penetration of moisture or saliva can be prevented.

[149] In some cases, after the oiling described above, the oil can be dried.

[150] In one embodiment of the present invention, one or more of the processes disclosed above can be controlled such that the fineness of the yarns that make up the lyocell multifilament is from 1.5 to 8.0 denier. The fineness of the yarn is understood to mean the fineness of one monofilament separated from the multifilament.

[151] In particular, the fineness of one thread can be, for example, 7.5 denier or less, 7.0 denier or less, 6.5 denier or less, 6.0 denier or less, 5.5 denier or less, 5.0 denier or less, or 4.5 denier or less. The lower limit of the fineness of one thread can be, for example, at least 2.0 denier, such as at least 2.5 denier, at least 3.0 denier, at least 3.5 denier, at least 4.0 denier, at least 4.5 denier, at least 5.0 denier, at least 5.5 denier or at least 6.0 denier. In these ranges, stable draw resistance and processability of filters for a smoking article can be obtained.

[152] Although there are no specific limitations, the spinning process may be used to provide the fineness ranges specified above. Alternatively, all spinning, coagulation, washing and oiling processes may be controlled to provide a uniform fineness range.

[153] The process of imparting crimp (e)

[154] The crimping process is the process of applying steam and/or roller pressure to the oiled lyocell multifilament in such a way as to produce a crimped rope and may be referred to as twisting.

[155] The crimping imparts a crimp to the multifilament and bulk characteristics to the fiber. The crimping may be accomplished by known crimping devices such as a press box and/or a steam box, and available crimping devices may be any device capable of providing, for example, steam pressure or roller pressure.

[156] In one embodiment of the invention, crimping may be accomplished by applying steam to the lyocell multifilament to preheat and swell the multifilament, and then pressing the multifilament with a pressure roller to form folds on the multifilament. A steam box may be used to apply steam, which may be located upstream of the twisting device.

[157] In one embodiment of the invention, crimping may be accomplished by applying steam and pressure to the multifilament by means of a pressure roller.

[158] In one embodiment of the invention, crimping may be accomplished by applying steam to the lyocell multifilament to preheat and swell the multifilament, and then applying pressure to the multifilament simultaneously with the application of steam using a pressure roller.

[159] In one embodiment of the invention, crimping may be accomplished by applying steam at a pressure of from 0.1 kgf/ ^cm2 to 2.0 kgf/ ^cm2 to the multifilament prior to introduction into the crimping device (e.g., a pressure roller). In some embodiments of the present invention, steam may be applied by means of a steam box at a pressure of 0.2 kgf/ ^cm2 , at least 0.3 kgf/ ^cm2 , at least 0.4 kgf/ ^cm2 , at least 0.5 kgf/ ^cm2 , or at least 0.6 kgf/ ^cm2 . In addition, the steam may be supplied under a pressure of 1.5 kgf/ ^cm2 or less, 1.4 kgf/ ^cm2 or less, 1.3 kgf/ ^cm2 or less, 1.2 kgf/ ^cm2 or less, 1.1 kgf/ ^cm2 or less, or 1.0 kgf/ ^cm2 or less. If the amount or pressure of the supplied steam is below the specified ranges, smooth formation of curls may not be possible. In addition, if the amount exceeds the upper limits, the flexibility of the thread increases, excessive curl is formed on the thread in the twisting device, and the thread may not pass through the twisting device.

[160] In one embodiment of the invention, crimping can be performed under a pressure of from 1.5 kgf/ ^cm2 to 4.0 kgf/ ^cm2 on the multifilament introduced into the twisting device using a roller. In some embodiments of the present invention, a pressure of at least 1.6 kgf/ ^cm2 , at least 1.7 kgf/ ^cm2 , at least 1.8 kgf/ ^cm2 , at least 1.9 kgf/ ^cm2 , at least 2.0 kgf/ ^cm2 , at least 2.1 kgf/ ^cm2 , at least 2.2 kgf/ ^cm2 , at least 2.3 kgf/ ^cm2 , at least 2.4 kgf/ ^cm2 or at least 2.5 kgf/ ^cm2 can be applied to the multifilament by means of a pressure roller. In some embodiments of the invention, a pressure of 3.9 kgf/ ^cm2 or less, 3.8 kgf/ ^cm2 or less, 3.7 kgf/ ^cm2 or less, 3.6 kgf/ ^cm2 or less, 3.5 kgf/ ^cm2 or less, 3.4 kgf/ ^cm2 or less, 3.3 kgf/ ^cm2 or less, 3.2 kgf/cm2 or less, 3.1 kgf/ ^cm2 or less, 3.0 kgf/ ^cm2 or less, 2.9 kgf/ ^cm2 or less, 2.8 kgf/ ^cm2 or less, 2.7 kgf/ ^cm2 or less, 2.6 kgf/ ^cm2 or less, or 2.5 kgf/ ^cm2 or less ^can be applied. If the roller pressure is below the lower limits, the number of curls formed may be insufficient. In addition, if the roller pressure exceeds these ranges, the pressing force may be so strong that the thread cannot be smoothly introduced into the twisting device or cannot pass through the pressing box. The action of the pressing roller, which provides pressure, may cause creases in the multifilament.

[161] In one embodiment of the invention, a knife device may be used to impart crimping, which exerts a predetermined pressure on the multifilament. The knife device controls the time the thread spends in the pressing box of the twisting machine, which helps to form the desired number of crimps (which affects the quality of the tow and the efficiency of the filter). For example, such a knife device may be located along the path of movement of the multifilament, which is pressed by a roller and then removed from the point of pressing of the roller.

[162] In one embodiment of the present invention, crimping may be accomplished by applying a pressure of 0.1 kgf/ ^cm2 to 2.0 kgf/ ^cm2 to the multifilament that has passed through the roller of the crimping device with a knife device. In some embodiments, the pressure applied by the knife device may be at least 0.2 kgf/ ^cm2 , at least 0.3 kgf/ ^cm2 , at least 0.4 kgf/ ^cm2 , or at least 0.5 kgf/ ^cm2 . In some embodiments, the upper limit of the pressure may be, for example, 1.5 kgf/ ^cm2 or less, 1.4 kgf/ ^cm2 or less, 1.3 kgf/ ^cm2 or less, 1.2 kgf/ ^cm2 or less, 1.1 kgf/ ^cm2 or less, or 1.0 kgf/ ^cm2 or less.

[163] In one embodiment of the invention, the crimping may be performed at a temperature of 120° to 250°. If the temperature is too low, the effect of stabilizing the crimp shape may not be very good, and if the temperature is too high, the fat concentration in the pressing box may increase, making it difficult to form the crimp. Therefore, considering these ranges of steam pressure, etc., the temperature may be adjusted appropriately to be at least 130°, at least 140°, or at least 150°, and at least 200°, at least 180°, or at least 160°.

[164] Binder Process (f)

[165] In one embodiment of the invention, the method may further comprise coating the oiled lyocell multifilament, or the lyocell multifilament (i.e., crimped tow) obtained by crimping, with a binder.

[166] If a filter for a smoking article is made from a tow, a binder may be used. The binder may increase the rigidity of filters for a smoking article made from a tow, preventing the filters from becoming jammed when making filters or cigarettes.

[167] The choice of method for coating the lyocell crimped tow with a binder is essentially not limited. For example, oiling can be accomplished by immersing the crimped tow in a bath filled with a binder (or a binder solution) so that the multifilament is completely immersed in the binder. Alternatively, coating with a binder can be accomplished by spraying (or applying) the binder (or binder solution) using a nozzle.

[168] The type or component of the binder that may be used in this case is the same as that disclosed above. Accordingly, their description will be omitted.

[169] In one embodiment of the invention, the binder (or binder solution) may comprise a solvent in addition to the components disclosed above. The solvent may comprise, for example, water, ethanol, propylene glycol and/or glycerin, and other variations are also possible. If the binder (or binder solution) comprises a solvent, the amount of solvent may be, for example, from about 20 wt.% to about 80 wt.% or from about 40 wt.% to about 60 wt.%, based on 100 wt.% of the total weight of the binder (or binder solution).

[170] The treatment with a binder may be performed at such a level that the purpose of the treatment with a binder disclosed above is achieved. For example, the treatment with a binder may be performed such that the amount of the binder is 20% by mass or less, such as 8% by mass to 15% by mass, based on 100% by mass of the multifilament treated with the oil and the binder. In this regard, the amount may refer to the dry weight after evaporation of the solvent or liquid component that may be included in the binder.

[171] After the binding agent has been applied to the twisted rope, it can be dried. The choice of drying temperature is essentially not limited, and, for example, drying can be carried out at room temperature (from about 10° to about 35°C).

[172] Other processes (g)

[173] After the crimping has been achieved, appropriate post-processing can be performed.

[174] In one embodiment of the invention, a second oiling (g1) may be additionally performed. The second oiling may prevent the occurrence of static charge in the tow and ensure the flexibility of the tow. The second oiling may be performed similarly to or in accordance with the oiling (d) disclosed above.

[175] In particular, the second oiling can be carried out by applying oil to the lyocell tow that has been processed using a crimping device. It can be advantageous in several processes carried out in the manufacture of a filter for a smoking article. For example, the second oiling not only allows the fibers and filters to stretch well in the air during the stretching process, but also prevents the fibers from being destroyed by the oil chains holding the lyocell during the stretching process. For this purpose, it is necessary to use a component derived from a fatty acid containing at least a predetermined number of carbon atoms, as disclosed above.

[176] The second oiling, as disclosed above, may be performed before or after the binder treatment. In some embodiments of the invention, the second oiling may be performed independently of the binder treatment.

[177] Even if the second oiling is performed as disclosed above, the second oiling may be performed as long as the amount or quantity of OPU oil in the material conforms to the ranges disclosed above.

[178] In one embodiment of the invention, drying (g2) may be additionally performed. Drying may be carried out, for example, at a temperature of 100°C to 130°C. The choice of drying method or process is not essentially limited, and the method may be carried out using known techniques. For example, hot air may be supplied to the tow, or the tow may be passed through a temperature-controlled room or left for a certain period of time in such a room.

[179] In one embodiment of the present invention, a method comprising a crimping step as disclosed above allows for a tow to be produced comprising 20 to 50 twists per inch. For example, the number of twists may be at least 25 pcs/inch, at least 30 pcs/inch, at least 35 pcs/inch, at least 40 pcs/inch, or at least 45 pcs/inch, and the upper limit may be, for example, 45 pcs/inch or less, 40 pcs/inch or less, 35 pcs/inch or less, 30 pcs/inch or less, or 25 pcs/inch or less. The number of twists and their uniformity may be adjusted depending on the pressure and temperature conditions associated with the twisting operation disclosed above.

[180] The manufacturing method according to the present invention may involve producing a tow with a fineness suitable for producing a filter for a smoking article and ensuring its functionality. The overall fineness of the tow depends on the number of threads that can be inserted into the filter wrapper. If the overall fineness is too low, it may not be possible to place a sufficient number of threads into the filter wrapper, which will result in a decrease in suction resistance. If the overall fineness is too high, the amount of filler in the filter wrapper becomes too large, which will result in the filter wrapper breaking, or it becomes difficult to control the amount of filler to achieve the required suction resistance for the filter. In this regard, in some embodiments of the present invention, a crimped tow with an overall fineness of from 15,000 to 45,000 denier may be provided. For example, the lower limit of the overall fineness may be at least 16,000, at least 17,000, at least 18,000, at least 19,000 or at least 20,000, and the upper limit may be, for example, 40,000 or less, 35,000 or less, 30,000 or less, or 25,000 or less. More specific numbers correspond to those disclosed above. If the overall fineness of the tow is outside these ranges, the processability of manufacturing filters for a smoking article will not be very high (a continuous cutting process is impossible), and the amount of tow placed in the filter wrapper when manufacturing filters for a smoking article will be insufficient or excessive, which will make it difficult to obtain sufficient filter properties (for example, suction resistance).

[181] The overall fineness of the tow, as disclosed above, can be determined depending on the fineness of one thread and the number of twists. According to the method proposed by the present invention, since the fineness of one fiber and the number of twists are controlled by the method disclosed above, the overall fineness of the tow suitable for producing filters for a smoking article and its functionality can be ensured.

[182] Although there are no specific limitations, lyocell material prepared by this method can be used in filters for smoking products.

[183] One embodiment of the present invention relates to a filter for a smoking article. The filter for the smoking article comprises a lyocell material, wherein the lyocell material may be the same as disclosed above.

[184] In particular, a filter for a smoking article according to the present invention is a filter for a smoking article comprising a lyocell material, wherein the lyocell material comprises a lyocell multifilament that is crimped and an oil supported on the lyocell multifilament. In some embodiments of the invention, the oil may comprise at least (a) an esterification product of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol; and (b) an esterification product of sorbitan and a fatty acid containing at least 16 carbon atoms.

[185] In some embodiments, the lyocell material may comprise oil in an amount of at least 2.0 wt.% based on 100 wt.% of the total amount of the lyocell material. Other descriptions of the components and amount of oil in accordance with embodiments of the present invention are the same as those disclosed above.

[186] In one embodiment of the invention, the fineness of one thread included in the lyocell multifilament may be from 1.5 to 8.0 denier. The specific numbers correspond to those disclosed above.

[187] In one embodiment of the invention, the lyocell multifilament that is crimped may be a crimped tow with an overall fineness of from 15,000 to 45,000 denier. The specific numbers are as disclosed above.

[188] In one embodiment of the invention, the crimped lyocell multifilament may contain from 20 to 50 crimps per inch. The specific numbers are as disclosed above.

[189] In one embodiment, the filter for a smoking article may further comprise a binder on the surface of the crimped lyocell multifilament or between the crimped lyocell multifilaments. The binder may increase the rigidity of the filters for a smoking article made from the tow, preventing the filters from being pinched during the manufacture of filters or cigarettes. The description of the type, components and amount of the available binder is similar to that disclosed above.

[190] In one embodiment of the invention, the filter for a smoking article may further comprise a wrapper (may be referred to as wrapping paper, filter paper or filter wrapper). For example, the wrapper may be a porous or non-porous paper in which the lyocell tow (i.e. at least an oil-treated and crimped tow) disclosed above is wrapped and which is capable of maintaining the shape of the filter (e.g. a column or a cylinder).

[191] In one embodiment of the invention, wherein a porous wrapper is used, the wrapper may have a porosity of from 10 Coresta Units (CU) to 50,000 CU. In particular, the lower limit of the porosity of the wrapper can be, for example, at least 1,000 CU, at least 5,000 CU, at least 10,000 CU, at least 15,000 CU, at least 20,000 CU, at least 25,000 CU, at least 30,000 CU, at least 35,000 CU, at least 40,000 CU, or at least 45,000 CU, and the upper limit can be, for example, 45,000 CU or less, 40,000 CU or less, 35,000 CU or less, 30,000 CU or less, 25,000 CU or less, or 20,000 CU or less. In one embodiment of the present invention, the wrapper may have a porosity in the range of 22,000 CU to 26,000 CU or 23,000 CU to 25,000 CU.

[192] In one embodiment of the invention, the density of the wrapper may be from 15 g/ ^cm2 to 60 g/ ^cm2 . In some embodiments, the lower limit of the density of the wrapper may be, for example, at least 20 g/ ^cm2 , at least 25 g/ ^cm2 , at least 30 g/ ^cm2 , at least 35 g/ ^cm2 , at least 40 g/ ^cm2 , at least 45 g/ ^cm2 , at least 50 g/ ^cm2 or at least 55 g/ ^cm2 , and the upper limit of the density of the wrapper may be, for example, 55 g/ ^cm2 or less, 50 g/ ^cm2 or less, 45 g/ ^cm2 or less, 40 g/ ^cm2 or less, 35 g/ ^cm2 or less, 30 g/ ^cm2 or less, 25 g/ ^cm2 or less, or 20 g/ ^cm2 or less. In embodiments of the present invention, the wrapper may have a density of at least 16 g/ ^cm2 , at least 17 g/ ^cm2 , at least 18 g/ ^cm2 , at least 19 g/ ^cm2 , at least 20 g/ ^cm2 or at least 21 g/ ^cm2 , and 25 g/ ^cm2 or less, 24 g/ ^cm2 or less, 23 g/ ^cm2 or less, 22 g/ ^cm2 or less, or 21 g/ ^cm2 or less.

[193] In one embodiment of the present invention, a filter for a smoking article may have a predetermined shape and size.

[194] For example, the filter may be in the form of a rod. In some embodiments of the invention, the filter for a smoking article may be in the form of a cylinder.

[195] In some embodiments, the length of the filter may be, for example, from 10 to 50 mm. In some embodiments, the length of the filter may have a lower limit of at least 15 mm, at least 20 mm, at least 25 mm, at least 30 mm, at least 35 mm, at least 40 mm, or at least 45 mm, and an upper limit of 45 mm or less, 40 mm or less, 35 mm or less, 30 mm or less, 25 mm or less, 20 mm or less, or 15 mm or less.

[196] In one embodiment of the present invention, a filter of such a length may have a circular cross-section, and the circumference of the circular cross-section may be from 10 to 40 mm. For example, the circumference of the filter may have a lower limit of at least 15 mm, at least 20 mm, at least 25 mm, at least 30 mm, or at least 35 mm, and an upper limit of 35 mm or less, 30 mm or less, 25 mm or less, 20 mm or less, or 15 mm or less.

[197] In one embodiment of the invention, the filter for the smoking article may correspond to a diameter retention factor (or hardness retention factor) of the filter before water injection, calculated according to Formula 1-1 below, of at least 85%.

[198] Formula 1-1

[199] Filter diameter (or hardness) retention coefficient (%) before water injection

[200] = {(original filter diameter (mm) - length by which the filter is compressed when the filter is compressed with a load of a certain mass (300 g) (mm))/(original filter diameter (mm))} × 100

[201] Although there are no particular limitations, in accordance with the above Formula 1-1, the diameter of the original filter or the length to which the filter is compressed may be confirmed by cross-sections at opposite ends of the filter having a predetermined length.

[202] For example, the filter diameter (or hardness) retention factor before water injection calculated according to Formula 1-1 above may be at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, or at least 95%. If the filter diameter (or hardness) retention factor (%) before water injection according to Formula 1-1 does not correspond to these retention factors, this indicates that the filter has insufficient hardness.

[203] In one embodiment of the invention, a filter for a smoking article may have a diameter retention rate (or hardness retention rate) of the filter after water injection, expressed according to Formula 1-2 below, of at least 80%.

[204] Formula 1-2

[205] Filter diameter (or hardness) retention rate (%) after water injection

[206] = {(original filter diameter (mm) - the length by which the filter is compressed when the filter is compressed with a load of a certain mass (300 g) after water injection (mm))/(original filter diameter (mm))} × 100

[207] Although there are no particular limitations, according to the above Formula 1-2, the diameter of the original filter or the length to which the filter is compressed may be confirmed by cross-sections at opposite ends of the filter having a predetermined length.

[208] With regard to the above Formula 1-2, the type of water to be injected is essentially not limited. For example, the water may be distilled water or tap water.

[209] In one embodiment of the present invention, according to the above Formula 1-2, the amount of water injected may be 20 μL. In this case, the amount of water injected may have an error within ±5 μL, ±4 μL, ±3 μL, ±1 μL, ±0.5 μL, or ±0.1 μL.

[210] In one embodiment of the present application, the diameter retention factor in accordance with Formula 1-2 may be measured 5 minutes after water is injected into the filter. In this case, the time during which the diameter retention factor is measured may have an error within ±3 minutes, ±2 minutes, ±1 minute, or ±30 seconds.

[211] In addition, the injection of water into the filter may be by injecting portions of water at equal intervals in the longitudinal direction of the filter (the direction of the greatest length of the filter shape, or in the case of a symmetrical filter, the longitudinal direction of the axis of symmetry). For example, if 20 μL of water is injected, the filter may be divided into three parts in the direction of the length of the filter (the direction of the greatest length of the filter shape), and 6 μL to 7 μL of water may be injected into a specific point (e.g., the center) or region of each of the three parts.

[212] For example, the filter diameter (or hardness) retention rate after water injection calculated according to the above Formula 1-2 may be at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91% or at least 92%. If the filter diameter (or hardness) retention rate after water injection according to Formula 1-2 does not correspond to the diameter retention rates, this indicates that the filter hardness has changed significantly due to moisture penetration. As in the experiment disclosed below, by applying oil to the filter for a smoking article according to the present invention as disclosed above, the hardness change can be prevented even after water injection, that is, a high level of the diameter (or hardness) retention rate can be obtained.

[213] In one embodiment of the invention, the moisture degradation coefficient of a filter for a smoking article, calculated according to Formula 2, may be equal to 8.0% or less.

[214] Formula 2

[215] Moisture Destruction Rate (%) = {(Filter Diameter Retention Rate Before Water Injection - Filter Diameter Retention Rate After Water Injection)/(Filter Diameter Retention Rate Before Water Injection)} × 100

[216] In Formula 2, the filter diameter retention coefficient before water injection can be calculated by Formula 1-1, and the filter diameter retention coefficient after water injection can be calculated by Formula 1-2.

[217] For example, the moisture degradation rate calculated by Formula 2 may be 7.5% or less or 7.0% or less, such as 6.5% or less, 6.0% or less, 5.5% or less, 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, 3.0% or less, 2.5% or less, or 2.0% or less. Conforming to the moisture degradation rates means that even if a certain amount of moisture penetrates into the filter, the degree of degradation of the filter due to the change in hardness will not be large. As in the experiments disclosed later, the filter for a smoking article according to the present invention can have a low degree of moisture degradation rate due to the application of oil as disclosed above.

[218] Although not particularly limited, the measurements of diameter change (rigidity change) and moisture degradation coefficient according to Formulas 1-1, 1-2 and 2 may be performed for a rod-shaped filter having a mass of at least 50 mg. In some embodiments, the mass of the filter may have a lower limit of, for example, at least 100 mg, at least 150 mg, or at least 200 mg, and an upper limit of 500 mg or less, 450 mg or less, 400 mg or less, 350 mg or less, 300 mg or less, 250 mg or less, or 200 mg or less.

[219] In another example of the present invention, a filter for a smoking article is provided that is capable of preventing a significant decrease in hardness even when moisture penetrates, that is, effectively preventing a decrease in the hardness of the filter under the influence of the smoker's saliva, etc. The above characteristics can be calculated using the following Formulas 1-1, 1-2, and 2.

[220] In one embodiment of the invention, the filter for the smoking article may correspond to a diameter retention factor (or hardness retention factor) of the filter before water injection, calculated according to Formula 1-1 below, of at least 85%.

[221] Formula 1-1

[222] Filter diameter (or hardness) retention coefficient (%) before water injection

[223] = {(original filter diameter (mm) - length by which the filter is compressed when the filter is compressed with a load of a certain mass (300 g) (mm))/(original filter diameter (mm))} × 100

[224] Although there are no particular limitations, in accordance with the above Formula 1-1, the diameter of the original filter or the length to which the filter is compressed may be confirmed by cross-sections at opposite ends of the filter having a given length.

[225] For example, the filter diameter (or hardness) retention factor before water injection calculated according to Formula 1-1 above may be at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, or at least 95%. If the filter diameter (or hardness) retention factor (%) before water injection according to Formula 1-1 does not correspond to these retention factors, this indicates that the filter has insufficient hardness.

[226] In one embodiment of the invention, a filter for a smoking article may have a diameter retention rate (or hardness retention rate) of the filter after water injection, expressed according to Formula 1-2 below, of at least 80%.

[227] Formula 1-2

[228] Filter diameter (or hardness) retention rate (%) after water injection

[229] = {(original filter diameter (mm) - the length by which the filter is compressed when the filter is compressed with a load of a certain mass (300 g) after water injection (mm))/(original filter diameter (mm))} × 100

[230] Although there are no particular limitations, according to the above Formula 1-2, the diameter of the original filter or the length to which the filter is compressed may be confirmed by cross-sections at opposite ends of the filter having a given length.

[231] With regard to the above Formula 1-2, the type of water injection is essentially not limited. For example, the water may be distilled water or tap water.

[232] In one embodiment of the present invention, according to the above Formula 1-2, the amount of water injected may be 20 μL. In this case, the amount of water injected may have an error within ±5 μL, ±4 μL, ±3 μL, ±1 μL, ±0.5 μL, or ±0.1 μL.

[233] In one embodiment of the present application, the diameter retention factor in accordance with Formula 1-2 may be measured 5 minutes after water is injected into the filter. In this case, the time during which the diameter retention factor is measured may have an error within ±3 minutes, ±2 minutes, ±1 minute, or ±30 seconds.

[234] In addition, the injection of water into the filter may be by injecting portions of water at equal intervals in the longitudinal direction of the filter (the direction of the greatest length of the filter shape, or in the case of a symmetrical filter, the longitudinal direction of the axis of symmetry). For example, if 20 μL of water is injected, the filter may be divided into three parts in the direction of the length of the filter (the direction of the greatest length of the filter shape), and 6 μL to 7 μL of water may be injected into a specific point (e.g., the center) or region of each of the three parts.

[235] For example, the filter diameter (or hardness) retention rate after water injection calculated according to the above Formula 1-2 may be at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91% or at least 92%. If the filter diameter (or hardness) retention rate after water injection according to Formula 1-2 does not correspond to the diameter retention rates, this indicates that the filter hardness has changed significantly due to moisture penetration. As in the experiment disclosed below, by applying oil to the filter for a smoking article according to the present invention as disclosed above, it is possible to prevent the hardness from changing even after water injection, that is, to obtain a high level of the diameter (or hardness) retention rate.

[236] In one embodiment of the invention, the moisture degradation coefficient of a filter for a smoking article, calculated according to Formula 2, may be equal to 8.0% or less.

[237] Formula 2

[238] Moisture Destruction Rate (%) = {(Filter Diameter Retention Rate Before Water Injection - Filter Diameter Retention Rate After Water Injection)/(Filter Diameter Retention Rate Before Water Injection)} × 100

[239] In Formula 2, the filter diameter retention coefficient before water injection can be calculated by Formula 1-1, and the filter diameter retention coefficient after water injection can be calculated by Formula 1-2.

[240] For example, the moisture degradation rate calculated by Formula 2 may be 7.5% or less or 7.0% or less, such as 6.5% or less, 6.0% or less, 5.5% or less, 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, 3.0% or less, 2.5% or less, or 2.0% or less. Conforming to the moisture degradation rates means that even if a predetermined amount of moisture penetrates into the filter, the degree of degradation of the filter due to the change in hardness will not be large. As in the experiments disclosed later, the filter for a smoking article according to the present invention can have a low degree of moisture degradation rate due to the application of oil as disclosed above.

[241] In one embodiment, the filter for the smoking article for which measurements are performed according to Formulas 1-1, 1-2 and 2 may have a predetermined shape and size.

[242] For example, the filter may be in the form of a rod. In some embodiments of the invention, the filter for a smoking article may be in the form of a cylinder.

[243] In some embodiments, the length of the filter may be, for example, from 10 to 50 mm. In some embodiments, the length of the filter may have a lower limit of at least 15 mm, at least 20 mm, at least 25 mm, at least 30 mm, at least 35 mm, at least 40 mm, or at least 45 mm, and an upper limit of 45 mm or less, 40 mm or less, 35 mm or less, 30 mm or less, 25 mm or less, 20 mm or less, or 15 mm or less.

[244] In one embodiment of the present invention, a filter of such a length may have a circular cross-section, and the circumference of the circular cross-section may be from 10 to 40 mm. For example, the circumference of the filter may have a lower limit of at least 15 mm, at least 20 mm, at least 25 mm, at least 30 mm, or at least 35 mm, and an upper limit of 35 mm or less, 30 mm or less, 25 mm or less, 20 mm or less, or 15 mm or less.

[245] In one embodiment of the invention, a filter for a smoking article may comprise a lyocell tow (i.e., a lyocell multifilament that is crimped), an oil applied to the lyocell multifilament, and a filter wrapper. The description of the lyocell tow and oil is similar to that disclosed above and is therefore omitted here.

[246] The wrapper may be a porous or non-porous paper in which the above-opened lyocell tow (i.e. at least an oil-treated and crimped tow) is wrapped and which is capable of maintaining the shape of the filter (e.g. a column or a cylinder).

[247] In one embodiment of the invention, wherein a porous wrapper is used, the wrapper may have a porosity of from 10 Coresta Units (CU) to 50,000 CU. In particular, the lower limit of the porosity of the wrapper can be, for example, at least 1,000 CU, at least 5,000 CU, at least 10,000 CU, at least 15,000 CU, at least 20,000 CU, at least 25,000 CU, at least 30,000 CU, at least 35,000 CU, at least 40,000 CU, or at least 45,000 CU, and the upper limit can be, for example, 45,000 CU or less, 40,000 CU or less, 35,000 CU or less, 30,000 CU or less, 25,000 CU or less, or 20,000 CU or less. In one embodiment of the present invention, the wrapper may have a porosity in the range of 22,000 CU to 26,000 CU or 23,000 CU to 25,000 CU.

[248] In one embodiment of the invention, the density of the wrapper may be from 15 g/cm ² to 60 g/cm ² . In some embodiments, the lower limit of the wrapper density may be, for example, at least 20 g/ ^cm2 , at least 25 g/ ^cm2 , at least 30 g/ ^cm2 , at least 35 g/ ^cm2 , at least 40 g/ ^cm2 , at least 45 g/ ^cm2 , at least 50 g/ ^cm2 or at least 55 g/ ^cm2 , and the upper limit of the wrapper density may be, for example, 55 g/ ^cm2 or less, 50 g/ ^cm2 or less, 45 g/ ^cm2 or less, 40 g/ ^cm2 or less, 35 g/ ^cm2 or less, 30 g/ ^cm2 or less, 25 g/ ^cm2 or less, or 20 g/ ^cm2 or less. In embodiments of the present invention, the wrapper may have a density of at least 16 g/ ^cm2 , at least 17 g/ ^cm2 , at least 18 g/ ^cm2 , at least 19 g/ ^cm2 , at least 20 g/ ^cm2 or at least 21 g/ ^cm2 , and 25 g/ ^cm2 or less, 24 g/ ^cm2 or less, 23 g/ ^cm2 or less, 22 g/ ^cm2 or less, or 21 g/ ^cm2 or less.

[249] Although not particularly limited, the measurements of diameter change (rigidity change) and moisture degradation coefficient according to Formulas 1-1, 1-2 and 2 may be performed for a filter in the form of a rod having a mass of at least 50 mg. In some embodiments, the mass of the filter may have a lower limit of, for example, at least 100 mg, at least 150 mg, or at least 200 mg, and an upper limit of 500 mg or less, 450 mg or less, 400 mg or less, 350 mg or less, 300 mg or less, 250 mg or less, or 200 mg or less.

[250] Other descriptions of filters for smoking products and the materials included in their composition are similar to those disclosed above and are therefore omitted here.

[251] One embodiment of the present invention relates to a method for producing a filter for a smoking article. The method is a method for producing a filter for smoking articles from lyocell, as disclosed above, and may be a method comprising a method for producing a lyocell material, as disclosed above.

[252] In particular, the method for producing a filter for a smoking article according to the present invention may comprise the following steps: oiling a lyocell multifilament; crimping the lyocell multifilament; and producing a filter using the crimped lyocell multifilament.

[253] In addition, the oil used to treat the multifilament may comprise at least (a) an esterification product of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol; and (b) an esterification product of sorbitan and a fatty acid containing at least 16 carbon atoms.

[254] Furthermore, in one embodiment of the present invention, the lyocell multifilament included in the filter for a smoking article may contain oil in an amount of at least 2.0 wt.% based on 100 wt.% of the total weight of the lyocell multifilament. In this case, the lyocell multifilament included in the filter for a smoking article is a multifilament treated with at least oil. For example, the lyocell material may be a lyocell multifilament that has undergone a first oiling, a lyocell multifilament that has undergone a first and second oiling, or a lyocell multifilament to which a binder, which will be disclosed below, is applied and has undergone oiling. In addition, the lyocell multifilament treated with oil and/or a binder as disclosed above may be a lyocell multifilament that has been crimped. The specific numerical values of the amount of oil are the same as those disclosed above.

[255] As for the method of manufacturing a filter for a smoking article, the other processes, except for the process of manufacturing a filter, are similar to those disclosed above for the lyocell material, so their description will be omitted here. In addition, descriptions that duplicate those given above will also be omitted.

[256] The process of manufacturing the filter can be carried out by a person skilled in the art using known methods. For example, the filter can be manufactured by molding a wrapper filled with a tow into a rod shape. Alternatively, the filter can be manufactured by cutting a filter paper filled with a rod-shaped tow into an appropriate length. The description of the wrapper is similar to that given above.

[257] Although there are no special restrictions, before filling the filter paper with the tow, the tow may be further stretched or treated with a plasticizer.

[258] In another embodiment of the present invention, a smoking article comprising a lyocell material is provided. The lyocell material has the same composition and/or characteristics as disclosed above, so its description will be omitted here.

[259] In another embodiment of the present invention, a smoking article is provided comprising a filter for the smoking article. The filter for the smoking article has the same composition and/or characteristics as disclosed above, so its description will be omitted here.

[260] In another embodiment of the present invention, an oil is provided that is applied (e.g., as a coating) to the lyocell tow. The oil according to the present invention is capable of overcoming the hydrophilicity of the surface of the lyocell material for a filter for a smoking article and improving the degree of reduction in stiffness of the lyocell material under the influence of moisture.

[261] In some embodiments, the oil may comprise (a) an esterification product of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol; and (b) an esterification product of sorbitan and a fatty acid containing at least 16 carbon atoms. In one embodiment, the oil may further comprise, as component (c), an alkylene oxide adduct with respect to component (b).

[262] The detailed description of each component included in the oil is similar to that given above. Accordingly, the description will be omitted here.

[263] Beneficial effects of the invention

[264] According to the present invention, there is provided a lyocell material for a filter for a smoking article capable of replacing commercially available cellulose acetate, and a filter for a smoking article containing the same. In particular, the present invention not only provides a lyocell material with excellent manufacturing processability and biodegradability, but also can improve the rigidity of the filter and the physical properties of smoking articles (e.g. cigarettes).

[265] Principle of the invention

[266] Hereinafter, the steps and effects of the disclosure will be disclosed in more detail using specific examples of the disclosure. However, the disclosure is given as an example, and the scope of protection of the invention is not limited to this disclosure.

[267] <Experiment 1: Evaluation of the immersion time of lyocell tow>

[268] The lyocell material was manufactured using the same technology as disclosed in the Preparation Example below. The terms not explicitly disclosed are within the scope of protection of the above disclosure.

[269] Example of production

[270] A pulp having an alpha cellulose content of 93.9% and a degree of polymerization (DPw) of 820 was mixed with an NMMO/ _H2O solvent having a propyl gallate content of 0.01 wt% to obtain a spinning solution for producing tow with a concentration of 11 wt%. Then, while maintaining the spinning temperature at 110°C in the spinning nozzle, the discharge amount and the spinning speed were appropriately adjusted, and the spinning solution was spun.

[271] The spinning solution in the form of a filament exiting from the spinning nozzle was fed into the coagulating liquid in the coagulation bath (coagulating liquid with a concentration of 75 wt% water and 25 wt% NMMO and a temperature of about 25°C) through the air gap portion. In this case, the cooling air in the air gap portion first coagulates the spinning solution at a temperature of 8°C and an air flow rate of 200 ^Nm3 /h. In addition, the concentration of the coagulating liquid was continuously monitored using a sensor and a refractometer.

[272] The coagulated lyocell yarns were then washed. Specifically, the yarn was introduced into a draw roll and the remaining NMMO in the yarn was removed by a washing liquid sprayed from a washing device. The washed yarn was then immersed in a bath of a predetermined oil concentration.

[273] The thread was treated with a pressure of 2 kgf/ ^cm2 using a pressure roller installed in the unloading section of the bath, and placed in a twisting machine to form folds. Specifically, to produce a bundle, steam under a pressure of 0.5 kgf/ ^cm2 was fed into the steam box, the roller pressure of the twisting device was set to 2.5 kgf/ ^cm2 , and the pressure of the knife device was set to 0.5 kgf/ ^cm2 .

[274] The resulting tow was subjected to a second oiling to prevent static charge and to provide flexibility, and immediately after the second oiling, the resulting tow was passed through a continuous dryer set at 120°C to obtain a dry finished tow.

[275] The resulting tow has a single strand fineness of 3.0 to 3.5 denier, an overall fineness of 36,000 to 40,000 denier, and a twist count of 25 to 35 pcs/inch.

[276] In particular, the oil types (components) and/or residual oil content (OPU) in the Examples and Comparative Examples differ as follows.

[277] Example 1

[278] Similar to the Manufacturing Example, an oiled lyocell tow was used. In this experiment, the oil used to make the tow contained about 60 wt.% isotridecyl stearate, about 22 wt.% sorbitan monooleate, about 16 wt.% polyoxyethylene sorbitan monooleate, the balance was water, and the OPU was 5.6 wt.%.

[279] Example 2

[280] Similar to the Manufacturing Example, an oiled lyocell tow was used. In this experiment, the oil used to make the tow contained about 50 wt.% isotridecyl stearate, about 27 wt.% sorbitan monooleate, about 21 wt.% polyoxyethylene sorbitan monooleate, the balance was water, and the OPU was 5.1 wt.%.

[281] Example 3

[282] The same lyocell tow was used as in Example 1, except that the OPU was 3.16 wt%.

[283] Example 4

[284] The same lyocell tow was used as in Example 1, except that the OPU was 2.15 wt%.

[285] Comparative example 1

[286] Lyocell tow was used in a similar manner to the Manufacturing Example, except for the oil treatment.

[287] Comparative example 2

[288] Similar to the Manufacturing Example, an oiled lyocell tow was used. JKP-107C oil, which can be classified as a hydrophilic oil, was used to manufacture the tow, and the OPC was 2.1 wt%. It is known that JKP-107C contains at least about 40 wt% polyoxyethylene alkyl ether, at least about 10 wt% polyethylene glycol, at least about 20 wt% polyethylene glycol alkyl ether, at least about 13 wt% polyoxyethylene alkyl phosphate, at least about 9 wt% dialkyl sulfosuccinate and/or its salt, at least about 3 wt% fatty alcohol amine, and at least about 5 wt% water.

[289] Comparative example 3

[290] The same lyocell tow was used as in Example 1, except that the OPU was 0.23 wt%.

[291] The immersion time was evaluated for each of the tows of Examples 1-3 and Comparative Examples 1-4, prepared as disclosed above, as follows.

[292] Method for estimating immersion time (seconds)

[293] The tows (oiled tows) according to Examples and Comparative Examples were cut into pieces of 8 cm in size. The tow samples prepared in Examples and Comparative Examples were placed in a beaker filled with 1,000 ml of water (the outer diameter of the beaker was 108 mm, the height was 158 mm, and the water level was about 12.5 cm), and the time (seconds) required for the tow to fall to the bottom of the sample was measured. The immersion time indicated in the table below is the arithmetic mean value obtained after repeating the above experiment three times for a tow sample taken from each Example or Comparative Example.

[294] [Table 1]

OPU (mass%)* Immersion time (unit: seconds (s)) Example 1 Hydrophobic oil 5.6 9.46 Example 2 Hydrophobic oil 5.5 8.99 Example 3 Hydrophobic oil 3.16 7.79 Example 4 Hydrophobic oil 2.15 6.12 Comparative example 1 - 1.35 Comparative example 2 Hydrophilic oil 2.1 2.02 Comparative example 3 Hydrophobic oil 0.23 1.58

[295] OPU: The measurement was performed in the manner described above.

[296] Using the above Table 1, it was confirmed that the immersion time of the tow in the Examples was longer than that in the Comparative Examples. The results showed that the surface of the tow in the Examples had greater hydrophobicity. Tows with greater hydrophobicity can more effectively prevent the reduction in hardness due to saliva when used as a filter material for smoking articles. This is confirmed by the experiment described below.

[297] <Experiment 2: Evaluation of the change in hardness of a filter containing lyocell tow>

[298] Example 4

[299] The lyocell tow in Example 1 was wrapped with wrapping paper (24,000 UE porous paper, density about 21 g/ ^cm2 ), and the cylindrical filter rod (weight 150 to 200 mg) had an axial length of 27 mm and a circumferential length of 24.22 mm.

[300] Example 5

[301] The filter rod was made similarly to Example 4, except for using the lyocell tow from Example 2.

[302] Example 6

[303] The filter rod was made similarly to Example 4, except for using the lyocell tow from Example 3.

[304] Comparative example 5

[305] The filter rod was made in a similar manner to Example 4, except for using the lyocell tow from Comparative Example 1.

[306] Comparative Example 6

[307] The filter rod was made in a similar manner to Example 4, except for using the lyocell tow from Comparative Example 2.

[308] Comparative Example 7

[309] The filter rod was made in a similar manner to Example 4, except for using the lyocell tow from Comparative Example 3.

[310] Comparative Example 8

[311] A filter rod was made similar to Example 4, except for using the lyocell tow from Comparative Example 4.

[312] For each filter in the Examples and Comparative Examples made in the manner disclosed above, the change in rigidity (or change in diameter) was estimated as follows.

[313] Change in filter hardness (%) or change in filter diameter (%)

[314] 20 μl of water (e.g. distilled water or tap water) was injected into each of the filters produced in Examples 5 to 8 and Comparative Examples 4 to 7, and the hardness changes (diameter changes) before the water injection and 5 minutes after the water injection were confirmed. For this purpose, water was injected in three portions at positions of 4.5 mm, 13.5 mm and 22.5 mm from one end of a 27 mm long filter rod. The amount of water injected was a value determined after a group of smokers independently measured the amount of moisture remaining in the filter after smoking the tobacco product.

[315] The change in filter hardness due to water penetration into the filter and the degree of filter degradation due to moisture can be calculated from the change in filter diameter as follows. The Filtrona DHT 200™ was used for these measurements.

[316] Formula 1-1

[317] Filter diameter (or hardness) retention coefficient (%) before water injection

[318] = {(original filter diameter (mm) - length by which the filter is compressed when the filter is compressed with a load of a certain mass (300 g) (mm))/(original filter diameter (mm))} × 100

[319] Formula 1-2

[320] Filter diameter (or hardness) retention rate (%) after water injection

[321] = {(original filter diameter (mm) - the length by which the filter is compressed when the filter is compressed with a certain mass (300 g) after water injection (mm))/(original filter diameter (mm))} × 100

[322] Formula 2

[323] Moisture Destruction Rate (%) = {(Filter Diameter Retention Rate Before Water Injection - Filter Diameter Retention Rate After Water Injection)/(Filter Diameter Retention Rate Before Water Injection)} × 100

[324] [Table 2]

The tourniquet used OPU (mass%)* Before water injection
Change in diameter (Formula 1-1, %) After water injection
Change in diameter (Formula 1-2, %) Moisture degradation coefficient (Formula 2, %) Example 5 Example 1 Hydrophobic oil 5.6 92.8 89.0 4.09 Example 6 Example 2 Hydrophobic oil
5.5 91.6 85.9 6.22 Example 7 Example 3 Hydrophobic oil
3.16 89.2 83.6 6.27 Example 8 Example 4 Hydrophobic oil
2.15 87.7 80.8 7.87 Comparative example 4 Comparative example 1 - Poor quality filter manufacturing* Poor quality of filter manufacturing - Comparative example 5 Comparative example 2 Hydrophilic oil
2.1 82.0 76.0 7.32 Comparative example 6 Comparative example 3 Hydrophobic oil
0.23 Poor quality of filter manufacturing Poor quality of filter manufacturing -

[325] OPU: The measurement was performed in the manner described above.

[326] Poor filter manufacturing: When making filters, the tow is unevenly distributed during the stretching process, clumps together, or is cut unevenly because it is not given rigidity.

[327] Table 2 shows that the degree of change in hardness (in particular, the change in hardness after water injection) in the Examples is higher than that in the Comparative Examples. The results show that the surface of the tow in the Examples has greater hydrophobicity. Tows with greater hydrophobicity can more effectively prevent the decrease in hardness due to saliva when used as a filter material for smoking articles.

Claims (32)

1. Lyocell material for a filter for a smoking product, containing: a lyocell multifilament that has been crimped; and an oil supported on the lyocell multifilament, in which the oil comprises (a) the esterification product of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol; and (b) the esterification product of sorbitan and a fatty acid containing at least 16 carbon atoms; and the lyocell material for a filter for a smoking article contains oil in an amount of at least 2.0 wt.% based on 100 wt.% of the total weight of the lyocell material. 2. A lyocell material for a filter for a smoking article according to claim 1, wherein the oil contains from 20 to 60 mass fractions (b) of the esterification product of sorbitan and a fatty acid containing at least 16 carbon atoms, based on 100 mass fractions of the esterification product (a) of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol. 3. A lyocell filter material for a smoking article according to claim 1, wherein the oil further comprises (c) an alkylene oxide adduct with respect to the esterification product (b). 4. A lyocell material for a filter for a smoking article according to claim 1, wherein the oil contains from 10 to 50 mass fractions (c) of an alkylene oxide adduct relative to the esterification product (b), based on 100 mass fractions of the esterification product (a) of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol. 5. The lyocell filter material for a smoking article according to claim 1, wherein the lyocell multifilament to which the crimp is imparted has an overall fineness of from 15,000 to 45,000 denier and contains from 20 to 50 crimps per inch. 6. A smoking article containing lyocell material according to paragraph 1. 7. A method for producing a lyocell material for a filter for a smoking article, comprising: oiling a lyocell multifilament; and imparting crimp to the lyocell multifilament, in which the oil comprises (a) the esterification product of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol, and (b) the esterification product of sorbitan and a fatty acid containing at least 16 carbon atoms; and the lyocell material for a filter for a smoking article contains oil in an amount of at least 2.0 wt.%, based on 100 wt.% of the total weight of the lyocell material. 8. The method according to claim 7, wherein the oil contains from 20 to 60 mass fractions of the esterification product (b) of sorbitan and a fatty acid containing at least 16 carbon atoms, based on 100 mass fractions of the esterification product (a) of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol. 9. The method according to claim 7, wherein the oil further comprises (c) an alkylene oxide adduct with respect to the esterification product (b). 10. The method according to claim 7, wherein the oil contains from 10 to 50 mass fractions (c) of an alkylene oxide adduct relative to the esterification product (b), based on 100 mass fractions of the esterification product (a) of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol. 11. The method of claim 7, wherein the lyocell multifilament has a total fineness of 15,000 to 45,000 denier and contains 20 to 50 twists per inch. 12. A filter for a smoking product comprising a lyocell material in which the lyocell material comprises: a lyocell multifilament which has been crimped; and an oil applied to the lyocell multifilament, the oil comprises (a) the esterification product of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol, and (b) the esterification product of sorbitan and a fatty acid containing at least 16 carbon atoms; and the lyocell material contains oil in an amount of at least 2.0 wt.%, based on 100 wt.% of the total amount of lyocell material. 13. The filter according to claim 12, wherein the oil contains from 20 to 60 mass fractions of the esterification product (b) of sorbitan and a fatty acid containing at least 16 carbon atoms, based on 100 mass fractions of the esterification product (a) of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol. 14. The filter according to claim 12, wherein the oil further comprises (c) an alkylene oxide adduct with respect to the esterification product (b). 15. The filter according to claim 12, wherein the oil contains from 10 to 50 mass fractions (c) of an alkylene oxide adduct relative to the esterification product (b), based on 100 mass fractions of the esterification product (a) of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol. 16. The filter of claim 12, wherein the lyocell multifilament that is crimped has an overall fineness of 15,000 to 45,000 denier and contains 20 to 50 crimps per inch. 17. A smoking article comprising a filter for a smoking article according to item 12. 18. A method for manufacturing a filter for a smoking article, comprising: oiling a lyocell multifilament; imparting a crimp to the lyocell multifilament; and manufacturing a filter using the lyocell multifilament imparted with a crimp, in which the oil comprises (a) the esterification product of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol, and (b) the esterification product of sorbitan and a fatty acid containing at least 16 carbon atoms; and the amount of oil used to treat the lyocell multifilament included in the filter for a smoking article is at least 2.0 wt.%, based on 100 wt.% of the total weight of the lyocell multifilament. 19. The method according to claim 18, wherein the oil contains from 20 to 60 mass fractions of the esterification product (b) of sorbitan and a fatty acid containing at least 16 carbon atoms, based on 100 mass fractions of the esterification product (a) of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol. 20. The method according to claim 18, wherein the oil further comprises (c) an alkylene oxide adduct with respect to the esterification product (b). 21. The method according to claim 18, wherein the oil contains from 10 to 50 mass fractions (c) of an alkylene oxide adduct relative to the esterification product (b), based on 100 mass fractions of the esterification product (a) of a fatty acid containing at least 16 carbon atoms and an aliphatic monohydric alcohol. 22. The method of claim 18, wherein the lyocell multifilament has a total fineness of 15,000 to 45,000 denier and contains 20 to 50 twists per inch.