RU2841581C2 - Lyocell material with modified cross section, cigarette filter and methods of their production - Google Patents

Abstract

FIELD: tobacco filters smoke.

SUBSTANCE: group of inventions relates to a method for manufacture of lyocell material with a modified cross section for a cigarette filter, to lyocell material with a modified cross section for a cigarette filter, a method for manufacture of a cigarette filter and a cigarette filter. Method for manufacturing a lyocell material with a modified cross section for a cigarette filter comprises: spinning a lyocell spinning solution using a spinning mechanism capable of forming a modified cross section having at least three projections; coagulation of spun lyocell spinning solution to produce lyocell multifilament; oiling the lyocell multifilament; and crimping by feeding the oiled lyocell multifilament into a crimping machine such that the lyocell multifilament is exposed to steam and pressure, in which the lyocell multifilament comprises a monofilament with a modified cross section, the modified cross section has at least three projections, each of at least three projections has coefficient of modified shape (K_s) 0.6 or more, calculated as: K_s = L/W and a width coefficient (K_w) from 0.5 to 2.0, calculated as: K_w = W₁/W₂, where: L is the length of each of the three projections, which is calculated as the distance from the centre of a straight line connecting two points, where one projection intersects with two projections immediately adjacent to one projection, to the end point of this one projection; W is width of each of three projections, wherein width is calculated as arithmetic average width of projection (W₁) at point corresponding to 10% of length (L), and width of projection (W₂), at point corresponding to 90% of length (L). Lyocell multifilament has total fineness from 15,000 denier to 45,000 denier, and the monothreads making up the lyocell multifilament have fineness of one fibre from 1.5 denier to 8.0 denier.

EFFECT: high technological efficiency of filter production, biodegradability of filters.

16 cl, 2 dwg, 1 tbl, 9 ex

Description

Field of technology

[1] Cross-reference to related applications

[2] This application claims priority based on Korean Patent Application No. 10-2021-0190178 filed December 28, 2021, the entire contents of which are incorporated herein.

[3] Field of technology

[4] The present invention relates to a lyocell material with a modified cross-section, a cigarette filter containing the lyocell material, and methods for producing the lyocell material and the cigarette filter.

State of the art

[5] Cellulose acetate fibers are mainly used as materials for cigarette filters. As is known, cellulose acetate is a biodegradable material, but a cigarette filter containing cellulose acetate retains its original appearance for one to two years even after entering the soil, and complete biological decomposition requires a significant amount of time. Considering that cigarette products are used for smoking, after which they are collected as waste and taken to a landfill, as well as the amount and toxicity of cigarette products thrown into the living environment and remaining in it, there is a need to further improve the biodegradability of cigarette filters.

[6] On the other hand, since cigarettes are personal leisure products whose users enjoy inhaling the smoke produced by combustion, the more uniform the concentration of smoke during smoking, the higher the assessment of the quality of cigarettes. One of the parameters that can be assessed in relation to the uniformity of smoke concentration during smoking is the resistance to draw, which is known to increase proportionally to the filtration efficiency of the filter. That is, a cigarette filter with a high resistance to draw ensures not only good filtration of harmful substances, but also high user satisfaction (quality).

[7] Therefore, there is a need to develop a filter material that can replace conventional cellulose acetate materials and provide filter properties such as draw resistance at an equivalent or higher level than the prior art.

Disclosure

Technical problem of the invention

[8] One of the objectives of the present invention is to develop a lyocell material capable of replacing commercially available cellulose acetate for cigarette filters.

[9] Another object of the present invention is to develop a lyocell material for a cigarette filter, wherein the lyocell material should be characterized by environmentally friendly production and high biodegradability during disposal.

[10] Another object of the present invention is to provide a lyocell material with a modified cross-section having a predetermined shape or form, for example satisfying the modified shape factor and width factor disclosed below.

[11] Another object of the present invention is to provide a lyocell material for a cigarette filter that is capable of sufficiently meeting or exceeding the performance requirements (e.g., draw resistance) of a material for cigarette filters.

[12] Another object of the present invention is to provide a lyocell filter for cigarettes.

[13] Another object of the present invention is to provide a cigarette comprising a lyocell filter.

[14] Another object of the present invention is to improve the manufacturability of the lyocell material, the lyocell filter and the cigarette.

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

Technical solution

[16] According to one embodiment of the present invention, there are provided a lyocell material (for example, a material satisfying the modified shape factor and width factor disclosed below) and having a modified cross-section of a predetermined shape, a cigarette filter comprising the lyocell material, and methods for producing the lyocell material and the cigarette filter.

[17] In particular, the inventors of the present invention confirm that, as disclosed below, a yarn with a modified cross-section satisfying a predetermined shape and fineness is capable of providing excellent filtration functions (e.g., draw resistance) due to an increased specific surface area compared to a yarn with a round or other similar cross-section, which makes it possible to obtain a lyocell material in the configuration disclosed below, a cigarette filter containing the lyocell material, and methods for producing the lyocell material and the cigarette filter.

[18] Hereinafter, a lyocell material, a cigarette filter containing the lyocell material, and methods for producing the lyocell material and the cigarette filter according to the present invention will be described in detail.

[19] In one embodiment, the present invention relates to a method for producing a lyocell material with a modified cross-section satisfying a given shape and thinness. The lyocell material can be used to produce a cigarette filter.

[20] More specifically, the method may comprise the following steps: spinning a lyocell spinning solution using a spinning mechanism capable of forming a modified cross-section having at least three projections; obtaining a lyocell multifilament by coagulating the spun lyocell spinning solution; oiling the lyocell multifilament; supplying steam and pressure to the lyocell multifilament, supplying the lyocell multifilament that has undergone oiling to a crimping machine to form crimps. In addition, the lyocell multifilament produced by the above-disclosed method (e.g., the oiled lyocell multifilament) may have an overall fineness of from 15,000 denier to 45,000 denier, and the monofilaments comprising the lyocell multifilament may have a single fiber fineness of from 1.5 denier to 8.0 denier.

[21] The lyocell material produced according to this method may have a modified cross-section. The "modified cross-section" may refer to a cross-section that is not circular in shape but has a shape with multiple projections. For example, as shown in FIG. 1, a cross-section in which multiple projections (e.g., three or more projections) extend from the center may be called a modified cross-section.

[22] In one embodiment of the invention, the lyocell material with a modified cross-section according to the present invention may comprise three or more projections branching from the center. In one or more embodiments of the invention, the lyocell material with a modified cross-section may have a cross-section in which four, five or more modified projections branch from the center in different directions.

[23] Although there are no specific restrictions, a three-pronged material may have a Y-shaped cross-section, and a four-pronged material may have a cross-shaped cross-section.

[24] In one embodiment of the present invention, the modified cross-section of the lyocell material produced according to the method may satisfy a predetermined modified shape factor and width factor.

[25] In particular, each projection extending from the center may have, in relation to the shape, a modified shape coefficient of 0.6 or more, calculated according to Formula 1, and a width coefficient from 0.5 to 2.0, calculated according to Formula 2:

[26] <Formula 1>

[27] Modified form factor = L/W

[28] <Formula 2>

[29] Width ratio = W ₁ /W ₂ .

[30] In the formula, the modified form factor L expresses the length of the projection extending from the center or the length in the direction of the branch of the projection. In particular, L, which denotes the length of the projection, can be calculated as the distance (for example, the greatest distance or length) from the center of the straight line corresponding to the width of the projection (the length of which is to be obtained) connecting the two points where one projection intersects each of the two projections immediately adjacent to one projection, to the end point of one projection.

[31] In the formula, the modified shape coefficient W expresses the width of the protrusion. Specifically, based on the line reflecting the length L of the given protrusion as disclosed above (i.e., based on L as the base line in FIG. 1), W is calculated as the arithmetic mean (W=( _W1 + _W2 )/2) of the width _W1 of the protrusion at a point corresponding to 10% of the length of the base line and the width _W2 of the protrusion at a point corresponding to 90% of the length of the base line. When calculating the widths W, _W1 and _W2 of the protrusion, the straight line for calculating the widths W, _W1 and _W2 of the protrusion may be perpendicular to the length L of the protrusion.

[32] In one embodiment of the invention, the length L and width W of the protrusion for calculating the modified shape factor may be the arithmetic mean obtained by calculating the length and width for each protrusion in the modified cross-section of the monofilament and then dividing by the number of protrusions.

[33] In one embodiment of the present invention, L may be greater than W.

[34] If a tow having the modified cross-section disclosed above is introduced into a cigarette filter, uniform filter properties (e.g. draw resistance, filter circumference, etc.) can be obtained.

[35] In one embodiment of the invention, the modified shape factor (Formula 1) of the lyocell material with a modified cross-section, calculated as disclosed above, may be 0.7 or more, 0.8 or more, 0.9 or more, 1.0 or more, 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, 1.5 or more, 1.6 or more, 1.7 or more, 1.8 or more, 1.9 or more, 2.0 or more, 2.1 or more, 2.2 or more, 2.3 or more, 2.4 or more, or 2.5 or more. In addition, the upper limit of the modified form coefficient may be, for example, 4.0 or less, 3.5 or less, for example, 3.0 or less, 2.9 or less, 2.8 or less, 2.7 or less, 2.6 or less, 2.5 or less, 2.4 or less, 2.3 or less, 2.2 or less, 2.1 or less, 2.0 or less.

[36] In one embodiment of the invention, the aspect ratio (Formula 2) of the lyocell material calculated as disclosed above may be 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1.0 or more, 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, 1.5 or more, 1.6 or more, 1.7 or more, or 1.8 or more. Furthermore, the upper limit of the aspect ratio may be 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less.

[37] Fibers with a modified cross-section that meet the modified shape factor and width factor may have an increased surface area, which can improve the smoke removal efficiency compared to fibers with a circular cross-section or fibers with a modified cross-section that do not meet the modified shape factor and width factor.

[38] In addition, if the modified shape ratio (Formula 1) and the width ratio (Formula 2) are smaller than the values disclosed above, the specific surface area may gradually become the area of a circular cross-section, and as a result, it may be impossible to obtain a sufficient specific surface area. In addition, if the modified shape ratio (Formula 1) and the width ratio (Formula 2) exceed the values disclosed above, it is difficult to realize the properties of the filter (e.g., draw resistance) even if the filaments are introduced in the same or similar amount (e.g., grams (g)) when producing the filter during the preparation of the cigarette filter, since the effect of obtaining a large specific surface area, which is a property of the modified cross-section, is reduced.

[39] Next, a method for producing a lyocell material according to one embodiment of the present invention will be described in detail.

[40] Spinning of lyocell spinning solution

[41] This process is a process of spinning a lyocell dope using a spinning mechanism to form a modified cross-section with at least three protrusions. The dope may contain lyocell dope, i.e., cellulose (or cellulose pulp) and N-methylmorpholine-N-oxide (NMMO).

[42] In this case, the choice of the type or shape of the spinning mechanism capable of forming a modified cross-section with at least three protrusions is essentially not limited. For example, it is possible to use a spinning mechanism with a shape corresponding to three or more protrusions. Alternatively, it is possible to use a spinning device with several holes, in which at least three holes are formed next to each other in such a way as to form three or more protrusions.

[43] 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 during disposal, 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, meaning that lyocell as a material is more environmentally friendly than cellulose acetate.

[44] In one embodiment of the invention, the amount of cellulose in the spinning solution may be from 5 to 15 mass%, based on 100 mass% of the total weight of the spinning solution. If the amount of cellulose is insufficient, it is difficult to obtain the desired properties of the lyocell fiber, and if the amount of cellulose exceeds the specified range, it is difficult to dissolve the cellulose in the solvent. In this case, the amount of cellulose in the spinning solution may be 6 mass% or more, 7 mass% or more, 8 mass% or more, 9 mass% or more, or 10 mass% or more, and the upper limit of the amount of cellulose may be, for example, 14 mass% or less, 13 mass% or less, 12 mass% or less, 11 mass% or less, 10 mass% or less, or 9 mass% or less.

[45] In one embodiment of the invention, the spinning solution may comprise an aqueous solution of NMMO. Taking into account the degree of dissolution of the cellulose and the process temperature, the aqueous solution may comprise, for example, from 80 to 95 mass parts of NMMO and from 5 to 20 mass parts of water.

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

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

[48] The temperature of the spinning mechanism nozzle, in particular the spinning temperature, 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 °C to 120 °C or from 100 °C to 110 °C.

[49] In one embodiment of the invention, spinning may be performed under controlled spinning conditions to ensure the fineness of the monofilament and/or the multifilament. For example, the spinning of the spinning solution may be performed under controlled conditions, under which the fineness of a single filament of the thread may be from 1.5 denier to 8.0 denier. For example, one or more spinning conditions, namely the amount of the spinning solution discharged and/or the spinning speed of the spinning solution, may be suitably adjusted so that the fineness of a single filament of the thread forming the lyocell material may be from 1.5 denier to 8.0 denier. In this case, the fineness of a single filament of the thread is understood to be the fineness of a single monofilament separated from the multifilament. In addition, in some cases, the overall fineness can be adjusted within a given range by changing the number of strands of the thread.

[50] Specifically, the fineness of a single fiber 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, or 4.5 denier or less. In addition, the lower limit of the fineness of a single fiber may be, for example, 2.0 denier or more, 2.5 denier or more, 3.0 denier or more, 3.5 denier or more, 4.0 denier or more, 5.0 denier or more, 5.5 denier or more, or 6.0 denier or more. Conforming to the above range may be more advantageous for ensuring stable draw resistance and processability of the cigarette filter.

[51] The spinning solution discharged from the spinning mechanism may be subjected to the coagulation process disclosed below.

[52] (b) Coagulation and multifilament formation

[53] In this process, the lyocell spinning solution is coagulated to produce a lyocell multifilament.

[54] For coagulation, a method can be used in which the spinning solution comes into contact with air and/or a coagulating solution.

[55] In one embodiment of the invention, coagulation may include: primary coagulation, which involves supplying cold air to the spun lyocell spinning solution; and secondary coagulation, which involves immersing the primarily coagulated spinning solution in a coagulating solution.

[56] In the coagulation method disclosed above, the lyocell spinning solution discharged from the spinning mechanism is first coagulated in the space (air gap zone) between the spinning mechanism and the coagulation bath. For example, in the air gap zone, cold air can be supplied to the outside from inside the spinning mechanism, starting from the air cooling portion located inside the spinning mechanism. In addition, the primary coagulation can be carried out by the so-called air cooling method or other methods known in the art.

[57] In one embodiment of the invention, the upper limit of the cold air temperature in the primary coagulation may be, for example, 15 °C or less. More specifically, the cold air may be air with a temperature of 14 °C or less, 13 °C or less, 12 °C or less, 11 °C or less, or 10 °C or less. If the temperature exceeds the above temperature, the coagulation of the spinning solution using cold air may be insufficient, and the spinning processability may be unsatisfactory.

[58] The lower limit of the cold air temperature may be determined taking into account the spinning workability and/or the uniformity of the cross-section of the thread. For example, if the cold air temperature is lower than 4°C, the surface of the spinning mechanism may cool down, the surface of the thread may become uneven, and the spinning workability may also deteriorate. In this case, the cold air temperature may be 5°C or more, 6°C or more, 7°C or more, 8°C or more, 9°C or more.

[59] The degree of supply of cold air can be adjusted taking into account sufficient coagulation, spinning technology and the effect on the physical properties of the thread. For example, air can be supplied to the spinning solution at an air flow rate of 70 ^Nm3 /h to 300 ^Nm3 /h. More specifically, the air flow rate can be 100 ^Nm3 /h or more or 150 ^Nm3 /h or more, and the upper limit of the air flow rate can be, for example, 250 ^Nm3 /h or less or 200 ^Nm3 /h or less.

[60] After the primary coagulation as disclosed above, the cooled spinning solution may be fed into a coagulation tank or bath containing a coagulating solution (secondary coagulation). For proper coagulation, the temperature of the coagulating liquid may be, for example, 30°C or lower or 25°C or lower. In addition, the temperature of the coagulating solution may be 10°C or higher, 15°C or higher, or 20°C or higher. Maintaining the temperature allows the coagulation rate to be maintained at a proper level.

[61] The choice of coagulating solution for secondary coagulation is essentially unlimited. For example, the coagulating solution may contain water and/or NMMO.

[62] Although there is no limitation as such, if the coagulating solution contains water and NMMO, the amount of water in the coagulating solution may be from 60 to 90 mass%, and the amount of NMMO in the coagulating solution may be from 10 to 40 mass%. In addition, the coagulating solution may contain from 70 to 80 mass% of water and from 20 to 30 mass% of NMMO. The concentration of the coagulating solution can be controlled and maintained during the production process using a sensor or similar device.

[63] (c) Flushing

[64] If necessary, after the above-mentioned coagulation and production of the multifilament, washing of the multifilament can be performed. The washing process allows the removal of NMMO and/or other impurities from the thread.

[65] The choice of washing methods is essentially unlimited. For example, washing can be carried out by introducing the coagulated lyocell multifilament into a washing bath using a pull roller. Alternatively, washing can be carried out by spraying a washing solution onto the multifilament, which is moved to the next stage using a pull roller.

[66] In this case, the choice of components of the washing solution is essentially unlimited. For example, the washing solution may contain water, as well as known additives.

[67] In addition, considering the reuse after washing etc., the washing solution can be used by setting the temperature to 100 °C or lower.

[68] (d) Oiling

[69] This process is intended to apply oil to the surface of the thread to reduce the friction acting on the thread and facilitate the formation of further opened twists.

[70] 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 onto the multifilament, which is moved to the next step by a pull roller.

[71] 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.

[72] In one embodiment of the invention, the oiling may be performed in such a way that the amount of oil may be about 5% by weight or less, based on 100% by weight of the oiled multifilament. More specifically, the amount of oil in the oiled multifilament may be 4% by weight or less, 3% by weight or less, or 2% by weight or less, and may be 0.5% by weight or more, 1% by weight or more, or 2% by weight or more.

[73] The choice of oils that can be used in this process is essentially unlimited, and any oil known in the art can be used.

[74] In some cases, oil drying may be performed after oiling.

[75] In one embodiment of the present invention, at least one of the above-disclosed processes may be performed under controlled conditions to ensure the fineness of the above-mentioned monofilament and/or multifilament. In this case, the fineness of one fiber of the thread is understood to mean the fineness of one monofilament separated from the multifilament.

[76] Specifically, the fineness of a single fiber 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, 4.0 denier or less, 3.5 denier or less, or 3.0 denier or less. In addition, the lower limit of the fineness of a single fiber may be, for example, 2.0 denier or more, 2.5 denier or more, 3.0 denier or more, 3.5 denier or more, or 4.0 denier or more. As confirmed by the comparative examples disclosed below, when the fineness of a single fiber of the thread does not correspond to the above-mentioned ranges, the draw resistance of the cigarette filter can be significantly reduced.

[77] Although there are no specific limitations, spinning may be used to provide the fineness ranges specified above. Alternatively, all spinning, coagulation, washing and oiling processes may be controlled to ensure that the fineness ranges specified for a single fibre are met.

[78] (e) Formation of twists

[79] Crimping is the process of applying steam and pressure to the oiled lyocell multifilament to form a crimped rope and thus may be referred to as the twisting process.

[80] The crimping imparts a waviness to the multifilament and, accordingly, the fibers can acquire bulk properties. The crimping can be carried out using known crimping machines, for example, those comprising a press and/or steam box, and the choice of crimping machines that can be used according to the present invention is essentially unlimited, provided that the machine is capable of providing steam pressure and roller pressure.

[81] In one embodiment of the invention, the crimps can be formed by applying steam to the lyocell multifilament to preheat and swell the multifilament, and then applying pressure to the multifilament via a pressure roller to form folds on the multifilament. In this case, a steam box can be used to apply the steam, which can be located at the front of the crimping machine.

[82] In one embodiment of the invention, the twists can be formed in such a way that the pressure on the multifilament by means of the pressure roller and the supply of steam are carried out simultaneously.

[83] In one embodiment of the invention, the crimps may be formed by applying steam to the lyocell multifilament to preheat and swell the multifilament, followed by applying pressure to the multifilament by means of a pressure roller and simultaneously applying steam.

[84] In one embodiment of the invention, the crimps can be formed by supplying steam at a pressure of from 0.1 kgf/ ^cm2 to 2.0 kgf/ ^cm2 to the already prepared multifilament, before feeding the multifilament to the crimping machine (in particular, the pressure roller). In one embodiment of the present invention, the steam box can supply steam at a pressure of 0.2 kgf/ ^cm2 or more, 0.3 kgf/ ^cm2 or more, 0.4 kgf/ ^cm2 or more, 0.5 kgf/ ^cm2 or more, or 0.6 kgf/ ^cm2 or more. Alternatively, the steam box may supply steam at 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 steam supply or steam pressure is less than the above values, the crimps may be formed unevenly. In addition, if the steam supply or steam pressure exceeds the above ranges, the flexibility of the yarn increases, and excessive crimps are formed in the crimping machine, which may prevent the yarn from passing through the crimping machine.

[85] In one embodiment of the invention, the crimps can be formed at a pressure of from 1.5 kgf/ ^cm2 to 4.0 kgf/ ^cm2 on the multifilament introduced into the crimping machine using a roller. In one embodiment of the present invention, the pressure roller makes it possible to act on the multifilament with a pressure of 1.6 kgf/ ^cm2 or more, 1.7 kgf/ ^cm2 or more, 1.8 kgf/ ^cm2 or more, 1.9 kgf/ ^cm2 or more, 2.0 kgf/ ^cm2 or more, ^2.1 kgf/ ^cm2 or more, 2.2 kgf/cm2 or more, 2.3 kgf/ ^cm2 or more, 2.4 kgf/ ^cm2 or more, or 2.5 kgf/ ^cm2 . In addition, the applied pressure may be 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. If the pressure on the roller is less than the above, it may not be possible to form the required number of curls. In addition, if the roller pressure exceeds the upper specified ranges, the pressing force may be so strong that the yarn cannot be smoothly introduced into the crimping machine or cannot pass through the pressing box. The action of the pressing roller applying pressure may cause creases to form on the multifilament.

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

[87] In one embodiment of the present invention, providing crimps can be performed 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 machine with a knife device. Such a knife device can be located on the path of movement of the multifilament, which is pressed by the roller and then removed from the point of pressure of the roller. In one embodiment of the present invention, the pressure applied by the knife device can be 0.2 kgf/ ^cm2 or more, 0.3 kgf/ ^cm2 or more, 0.4 kgf/ ^cm2 or more, or 0.5 kgf/ ^cm2 or more. Alternatively, the upper pressure limit 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.

[88] In one embodiment of the invention, the curls can be formed at a temperature of 120 °C to 250 °C. If the temperature is too low, the effect of stabilizing the curl shape may not be very good, and if the temperature is too high, the concentration of the oil components in the pressing box may increase, making it difficult to form the curls. Therefore, taking into account the steam pressure disclosed above, the temperature can be appropriately controlled at 130 °C or more, 140 °C or more, or 150 °C or more, 200 °C or less, 180 °C or less, or 160 °C or less.

[89] In one embodiment of the invention, the formation of crimps may be performed until the crimp coefficient expressed by Formula 1 is met. In this case, the pressure exerted on the thread introduced into the crimping machine may be applied by a roller.

[90] <Formula 1>

[91] 1.01 ≤ tortuosity coefficient ≤ 1.30

[92] in which, according to formula 1, the crimp coefficient is calculated as V ₁ /V ₀ , where V ₀ is the thread speed before the multifilament that has undergone oiling is fed into the crimping machine, and V ₁ is the thread speed captured by the roller in the crimping machine. In this case, the speed of passage may be understood as the speed at which the multifilament fed during the formation of the crimps (or introduced into the crimping machine) is moved between the steam process and/or the pressure roller process.

[93] The method carried out under the above-mentioned conditions can ensure the formation of uniform twists on the tow. For example, as will be confirmed by the experiments disclosed below, in the tows produced in the Example under the conditions corresponding to Formula 1, the upper and lower limits of the range of the number of twists calculated as the arithmetic mean are closer than in the Comparative Example (i.e., the uniformity of the tow is ensured). In addition, the crimped cord produced and uniformly formed under the conditions corresponding to Formula 1 can ensure the uniform arrangement of fibers or strands of fibers when producing a cigarette filter. Accordingly, as will be disclosed below, high resistance to draw can be ensured.

[94] In addition, the method carried out under the conditions corresponding to Formula 1 can be advantageous for obtaining a good shape of the crimps and a good modified shape factor and width factor of the tow. A crimped tow having a good shape and corresponding to a modified shape factor and width factor within the above ranges can be advantageous for improving the resistance to tightening.

[95] In an alternative embodiment in which the Formula 1 ranges are not met, the conditions for manufacturing the tow become inadequate, and therefore the tow cannot be manufactured; or even if the tow can be manufactured, the shape of the resulting twists is poor. In addition, due to the non-uniformity of the tow, the manufacturability of the cigarette filter is low. As a result, it is difficult to obtain a filter with excellent draw resistance.

[96] (f) Other

[97] After the formation of the curls, appropriate post-processing can be carried out.

[98] In one embodiment of the invention, a secondary oiling may additionally be performed (g). The secondary oiling may prevent the occurrence of static charge in the tow and ensure the flexibility of the tow. The secondary oiling may be similar or analogous to the oiling (d) disclosed above.

[99] In one embodiment of the invention, drying (h) may additionally be performed. Drying may be performed, for example, at a temperature of 100 °C to 130 °C. The choice of the type or method of drying is essentially not limited, and known techniques may be used. For example, drying may be performed by applying hot air to the tow, holding the tow in a room with a controlled temperature for a certain period of time, or passing the tow through a room with a controlled temperature.

[100] According to one embodiment of the present invention, by forming crimps, it is possible to obtain a tow having 20 to 50 crimps per inch. For example, the number of crimps may be 25 pcs/inch or more, 30 pcs/inch or more, 35 pcs/inch or more, 40 pcs/inch or more, or 45 pcs/inch or more, and the upper limit of the number of crimps 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 and uniformity of crimps can be adjusted by twisting, for example, by a crimp ratio, etc. The twisted rope produced according to the method of the present invention not only contains the above-mentioned number of twists, but also contains uniformly formed twists as disclosed above, so that a high level of draw resistance can be ensured when producing a cigarette filter, as disclosed below.

[101] According to the present invention, a lyocell material (crimped tow) with a fineness suitable for producing a cigarette filter and ensuring its functionality can be provided. For example, a crimped tow with a total fineness of 15,000 to 45,000 denier can be obtained. For example, the lower limit of the total fineness may be 16,000 or more, 17,000 or more, 18,000 or more, 19,000 or more, or 20,000 or more, and the upper limit of the total fineness may be, for example, 40,000 or less, 35,000 or less, 30,000 or less, or 25,000 or less. If the total fineness is outside the above ranges, the filling of the filter wrapper with thread may be insufficient and, accordingly, the filter properties (e.g., draw resistance, etc.) may be deteriorated. Alternatively, if the overall thread fineness is outside the ranges, the filling of the filter wrapper with thread becomes excessive, resulting in the possibility of the filter wrapper breaking or difficulty in controlling the amount of thread inserted to achieve the required draw resistance for the cigarette filter.

[102] In one embodiment of the present invention, the fineness of the lyocell multifilament can be adjusted to an appropriate value depending on the circumference of the cigarette filter.

[103] For example, if the lyocell material is used in an (ultra)fine filter (e.g. a filter rod with a circumference of 19 mm or more), the overall fineness of the lyocell multifilament may be between 15,000 and 25,000 denier. In particular, the overall fineness of the lyocell multifilament used in the ultrafine filter may be 16,000 denier or more, 17,000 denier or more, 18,000 denier or more, 19,000 denier or more, 20,000 denier or more, 21,000 denier or more, 22,000 denier or more, 23,000 denier or more, or 24,000 denier or more, and may be 24,000 denier or less, 23,000 denier or less, 22,000 denier or less, 21,000 denier or less, 20,000 denier or less, 19,000 denier or less, 18,000 denier or less, 17,000 denier or less, or 16,000 denier or less. In addition, in this case, the fineness of one fiber of lyocell monofilament may be, for example, 4.5 denier or more, 5.0 denier or more, 5.5 denier or more, 6.0 denier or more, 6.5 denier or more, 7.0 denier or more, or 7.5 denier or more.

[104] In one or more embodiments of the invention, when the lyocell material is used in a conventional filter (e.g., a filter rod with a circumference of 19 mm or greater), the overall fineness of the lyocell multifilament can be from 25,000 to 45,000 denier. Specifically, the total fineness of the lyocell multifilament used in the conventional filter may be 26,000 or more, 27,000 or more, 28,000 or more, 29,000 or more, 30,000 or more, 31,000 or more, 32,000 or more, 33,000 or more, 34,000 or more, 35,000 or more, 36,000 or more, 37,000 or more, 38,000 or more, 39,000 or more, 40,000 or more, 41,000 or more, 42,000 or more, 43,000 or more, or 44,000 or more, and may be 44,000 or less, 43,000 or less, 42 000 or less, 41,000 or less, 40,000 or less, 39,000 or less, 38,000 or less, 37,000 or less, 36,000 or less, 35,000 or less, 34,000 or less, 33,000 or less, 32,000 or less, 31,000 or less, 30,000 or less, 29,000 or less, 28,000 or less, 27,000 or less, or 26,000 or less. In addition, in this case, the fineness of one fiber of the lyocell monofilament may be, for example, 5.0 denier or less, 4.5 denier or less, 4.5 denier or less, 4.0 denier or less, 3.5 denier or less, 3.0 denier or less, 2.5 denier or less, or 2.0 denier or less.

[105] Thus, the present invention makes it possible to obtain a lyocell material with a total fineness within the above-mentioned ranges, in particular with a fineness that allows for ensuring a filtration efficiency that is generally suitable for both a conventional and an (ultra)fine filter. The total fineness of the tow can be determined by the fineness of a single fiber of the thread and the number of twists. In the method according to the present invention, the fineness of a single fiber and the number of twists can be adjusted in the manner disclosed above, and accordingly, the above-mentioned total fineness of the tow suitable for producing a cigarette filter and its functionality can be ensured.

[106] In one or more embodiments, the present invention relates to a lyocell material with a modified cross-section. The lyocell material with a modified cross-section can be produced, for example, by the method for producing a lyocell material with a modified cross-section disclosed above. In particular, the lyocell material with a modified cross-section can be produced using all processes including spinning, coagulation, washing, oiling, and crimping.

[107] More specifically, the lyocell material with a modified cross-section may be a crimped cord made by crimping a lyocell multifilament. In this case, the lyocell multifilament may comprise a monofilament with a modified cross-section and have a total fineness of from 15,000 denier to 45,000 denier, and the monofilaments constituting the lyocell multifilament may have a single fiber fineness of from 1.5 denier to 8.0 denier.

[108] In addition, the modified cross-section of the monofilament may have at least three protrusions, wherein each protrusion may have a modified shape factor of 0.6 or more and a width factor of 0.5 to 2.0. The specific values of these factors are similar to those disclosed above. In addition, as disclosed above, the modified shape factor and the width factor may be calculated as follows:

[109] <Formula 1>

[110] Modified form factor = L/W

[111] <Formula 2>

[112] Width ratio = W ₁ /W ₂

[113] where in formulas 1 and 2, L expresses the length of each of the three projections, the length being calculated as the distance from the center of the straight line connecting the two points where one projection intersects the two projections immediately adjacent to one projection to the end point of that one projection. In addition, W expresses the width of each of the three projections, the width being calculated as the arithmetic mean of the width (W ₁ ) of the projection at the point corresponding to 10% of the length L and the width (W ₂ ) of the projection at the point corresponding to 90% of the length L. A detailed description is given below.

[114] In one embodiment of the invention, the lyocell material may be manufactured using a process that corresponds to at least the following <Formula 1>.

[115] In particular, the lyocell material may be or comprise a crimped tow produced by feeding the tow into a crimping machine capable of forming crimps under conditions corresponding to a crimp coefficient expressed by Formula 1:

[116] <Formula 1>

[117] 1.01 ≤ tortuosity coefficient ≤ 1.30

[118] where, according to formula 1, the crimping coefficient is calculated as V ₁ /V ₀ , where V ₀ is the speed of the thread before feeding the multifilament into the crimping machine, and V ₁ is the speed of passage of the thread captured by the roller in the crimping machine.

[119] In one embodiment of the invention, the crimped rope may contain from 20 to 50 crimps per inch. Specific values are similar to those disclosed above.

[120] In one embodiment of the invention, the tow, i.e., the crimped lyocell multifilament, may have an overall fineness of from 15,000 to 45,000 denier. For example, the lyocell multifilament may have an overall fineness of from 15,000 to 25,000 denier or from 25,000 to 45,000 denier. The specific values are similar to those disclosed above.

[121] In one embodiment of the invention, the monofilaments comprising the lyocell multifilament may have a single fiber fineness of from 1.5 denier to 8.0 denier. The specific values are similar to those disclosed above.

[122] As disclosed above, in one embodiment of the present invention, the fineness of the lyocell multifilament can be adjusted to an appropriate value depending on the circumference of the cigarette filter.

[123] For example, if the lyocell material is used in an (ultra)fine filter (e.g. a filter rod with a circumference of 19 mm or more), the overall fineness of the lyocell multifilament may be between 15,000 and 25,000 denier. In particular, the overall fineness of the lyocell multifilament used in the ultrafine filter may be 16,000 denier or more, 17,000 denier or more, 18,000 denier or more, 19,000 denier or more, 20,000 denier or more, 21,000 denier or more, 22,000 denier or more, 23,000 denier or more, or 24,000 denier or more, and may be 24,000 denier or less, 23,000 denier or less, 22,000 denier or less, 21,000 denier or less, 20,000 denier or less, 19,000 denier or less, 18,000 denier or less, 17,000 denier or less, or 16,000 denier or less. In addition, in this case, the fineness of one fiber of lyocell monofilament may be, for example, 4.5 denier or more, 5.0 denier or more, 5.5 denier or more, 6.0 denier or more, 6.5 denier or more, 7.0 denier or more, or 7.5 denier or more.

[124] In one or more embodiments of the invention, when the lyocell material is used in a conventional filter (e.g., a filter rod with a circumference of 19 mm or greater), the overall fineness of the lyocell multifilament can be from 25,000 to 45,000 denier. Specifically, the total fineness of the lyocell multifilament used in the conventional filter may be 26,000 or more, 27,000 or more, 28,000 or more, 29,000 or more, 30,000 or more, 31,000 or more, 32,000 or more, 33,000 or more, 34,000 or more, 35,000 or more, 36,000 or more, 37,000 or more, 38,000 or more, 39,000 or more, 40,000 or more, 41,000 or more, 42,000 or more, 43,000 or more, or 44,000 or more, and may be 44,000 or less, 43,000 or less, 42 000 or less, 41,000 or less, 40,000 or less, 39,000 or less, 38,000 or less, 37,000 or less, 36,000 or less, 35,000 or less, 34,000 or less, 33,000 or less, 32,000 or less, 31,000 or less, 30,000 or less, 29,000 or less, 28,000 or less, 27,000 or less, or 26,000 or less. In addition, in this case, the fineness of one fiber of the lyocell monofilament may be, for example, 5.0 denier or less, 4.5 denier or less, 4.5 denier or less, 4.0 denier or less, 3.5 denier or less, 3.0 denier or less, 2.5 denier or less, or 2.0 denier or less.

[125] Thus, according to the present invention, it is possible to obtain a lyocell material with a controlled fineness, which allows, in general, to ensure filtration efficiency for both a conventional and an (ultra)fine filter.

[126] Other disclosures relating to the lyocell material are similar to those provided in connection with the method for making the lyocell material and will therefore be omitted.

[127] In one or more embodiments, the present invention relates to a method for making a cigarette filter. The method may comprise all of the processes of the method for making a lyocell material with a modified cross-section disclosed above.

[128] More specifically, a method for producing a cigarette filter may comprise: spinning a lyocell dope using a spinning mechanism capable of forming a modified cross-section having at least three projections; coagulating the spun lyocell dope to obtain a lyocell multifilament; oiling the lyocell multifilament; forming crimps by feeding the lyocell multifilament that has undergone oiling to a crimping machine by applying steam and pressure to the lyocell multifilament; and producing a filter using the resulting tow with crimps.

[129] Furthermore, with respect to the method of manufacturing a cigarette filter (in particular, the process of manufacturing a lyocell material), at least one of the processes can be carried out under controlled conditions such that the lyocell multifilament will have an overall fineness of from 15,000 denier to 45,000 denier, and the monofilaments constituting the lyocell multifilament will have a single fiber fineness of from 1.5 denier to 8.0 denier.

[130] Among the processes related to the method of manufacturing a cigarette filter, the processes duplicating the above-disclosed processes with respect to the lyocell material will be omitted since their contents are the same.

[131] With respect to the method of manufacturing a cigarette filter, the lyocell material with a modified cross-section used in the method of manufacturing a cigarette filter may be a crimped tow produced by crimping a lyocell multifilament. In this case, the lyocell multifilament may comprise a monofilament with a modified cross-section and have a total fineness of from 15,000 denier to 45,000 denier, and the monofilaments constituting the lyocell multifilament may have a single fiber fineness of from 1.5 denier to 8.0 denier. In addition, the modified cross-section of the monofilament may have at least three protrusions, wherein each protrusion may have a modified shape factor of 0.6 or more and a width factor of from 0.5 to 2.0. The specific values of these factors are similar to those disclosed above. In addition, as disclosed above, the modified shape factor and the width factor can be calculated as follows:

[132] <Formula 1>

[133] Modified form factor = L/W

[134] <Formula 2>

[135] Width ratio = W ₁ /W ₂

[136] where in formulas 1 and 2, L expresses the length of each of the three projections, the length being calculated as the distance from the center of the straight line connecting the two points where one projection intersects the two projections immediately adjacent to the one projection to the end point of one projection. In addition, W expresses the width of each of the three projections, the width being calculated as the arithmetic mean of the width (W ₁ ) of the projection at the point corresponding to 10% of the length L and the width (W ₂ ) of the projection at the point corresponding to 90% of the length L. A detailed description is given below.

[137] In one embodiment of the invention, the formation of twists may be performed until the twist coefficient expressed by <Formula 1> is met:

[138] <Formula 1>

[139] 1.01 ≤ tortuosity coefficient ≤ 1.30

[140] in which, according to formula 1, the crimping coefficient is calculated as V ₁ /V ₀ , where V ₀ is the speed of movement of the thread before feeding the multifilament, which has undergone oiling, into the crimping machine, and V ₁ is the speed of passage of the thread captured by the roller in the crimping machine.

[141] In one embodiment of the invention, the crimped rope may contain from 20 to 50 crimps per inch. The detailed description is similar to that disclosed above and will therefore be omitted.

[142] The subsequent processing performed after the formation of the twists in the method for manufacturing a cigarette filter can be suitably performed by those skilled in the art using known methods. For example, the cigarette filter can be manufactured by forming a rod with a tow-filled wrapper (may be called wrapping paper, filter paper, or filter wrapper). Alternatively, the cigarette filter can be manufactured by cutting the rod-shaped filter paper filled with tow to an appropriate length.

[143] The wrapper may be a porous or non-porous paper wrapping the aforementioned lyocell tow (i.e., at least an oiled and crimped tow) and may support the shape of the filter (e.g., a column or a cylinder).

[144] In one embodiment of the invention, in which 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 may be, for example, 1000 CU or more, 5000 CU or more, 10000 CU or more, 15000 CU or more, 20000 CU or more, 25000 CU or more, 30000 CU or more, 35000 CU or more, 40000 CU or more, or 45000 CU or more, and the upper limit of the porosity of the wrapper may be, for example, 45000 CU or less, 40000 CU or less, 35000 CU or less, 30000 CU or less, 25000 CU or less, 20000 CU or less, 15000 CU or less, 10000 CU or less, or 5000 CU or less.

[145] In one embodiment of the present invention, the cigarette filter may have a predetermined shape and size.

[146] For example, a cigarette filter may be rod-shaped. More precisely, a cigarette filter may be cylindrical.

[147] In addition, the cigarette filter may have a length of, for example, from 10 to 150 mm. More specifically, the lower limit of the length of the cigarette filter may be 20 mm or more, 30 mm or more, 40 mm or more, 50 mm or more, 60 mm or more, 70 mm or more, 80 mm or more, 90 mm or more, 100 mm or more, 110 mm or more, 120 mm or more, 130 mm or more, 140 mm or more, or 150 mm or more. In addition, the upper limit of the length of the cigarette filter may be 150 mm or less, 140 mm or less, 130 mm or less, 120 mm or less, 110 mm or less, 100 mm or less, 90 mm or less, 80 mm or less, 70 mm or less, 60 mm or less, 70 mm or less, 60 mm or less, 50 mm or less, 40 mm or less, 30 mm or less, or 20 mm or less.

[148] In one embodiment of the present invention, a cigarette filter with a length corresponding to the specified ranges may have a circular cross-section, and the circumference of the circular cross-section may be from 10 to 30 mm. For example, the lower limit of the circumference of the cigarette filter may be 15 mm or more, 20 mm or more, or 25 mm or more, and the upper limit of the circumference of the cigarette filter may be 25 mm or less, 20 mm or less, or 15 mm or less.

[149] Although there are no special restrictions, the rope can be unraveled or treated with a plasticizer before filling the filter paper.

[150] In one embodiment of the invention, a cigarette filter made according to the method may have a draw resistance of 185 mm H ₂ O or more, measured according to KS H ISO 6565. More specifically, the draw resistance of the cigarette filter may be 190 mm H ₂ O or more, 200 mm H ₂ O or more, 210 mm H ₂ O or more, 220 mm H ₂ O or more, 230 mm H ₂ O or more, 240 mm H ₂ O or more, 250 mm H ₂ O or more, 260 mm H ₂ O or more, 270 mm H ₂ O or more, 280 mm H ₂ O or more, 290 mm H ₂ O or more, 300 mm H ₂ O or more, 310 mm H ₂ O or more, 320 mm H ₂ O or more, 330 mm H ₂ O or more, 340 mm H ₂ O or more, 350 mm H ₂ O or more, 360 mm H ₂ O or more, 370 mm H ₂ O or more, 380 mm H ₂ O or more, 390 mm H ₂ O or more, 400 mm H ₂ O or more, 410 mm H ₂ O or more, 420 mm H ₂ O or more, 430 mm H ₂ O or more, 440 mm H ₂ O or more, or 450 mm H ₂ O or more. In addition, the upper limit of tightening resistance may be, for example, 920 mm H ₂ O or less. In particular, the upper limit of the tightening resistance may be, for example, 910 mm _H2O or less, 900 mm _H2O or less, 890 mm _H2O or less, 880 mm H2O or less, 870 mm _H2O or less, 860 mm _H2O or less, 850 mm _H2O or less, 840 mm _H2O or less, 830 mm _H2O or less, 820 mm _H2O or less, 810 mm _H2O or less, 800 mm _H2O or less, 750 mm _H2O or less, 650 mm _H2O or less, 600 mm _H2O or less, 550 mm _H2O or less, 500 mm _H2O or less, 450 mm _H2O or _less , 400 mm _H2O or less, 390 mm _H2O or less, 380 mm _H2O or less, 370 mm H2O or less, 360 mm _H2O or less, 350 mm _H2O or less, 340 mm _H2O or less, 330 mm _{H2O or less, 320 mm H2O or} less, 310 mm _H2O or less, ₃₀₀ mm H2O or less, 290 mm _H2O or less, 280 mm _H2O or less, 270 mm _H2O or less, 260 mm _H2O or less, 250 mm _H2O or less, 240 mm _H2O or less, 230 mm H2O or less, ₂₂₀ mm _H2O or less, 210 mm _H2O or less, or 200 _{mm H2O} or less.

[151] Although there is no particular limitation, the draw resistance may be measured for a filter rod with a circumference of 10 to 30 mm or 15 to 27 mm. The circumference of a cigarette filter may be determined by the number of twists of the tow, the quality of the tow (for example, the uniformity of the shape of the twist), etc., and the draw resistance of a cigarette filter may be determined by the thinness and cross-section.

[152] Although there are no specific limitations, the draw resistance may be measured for a filter rod containing a wrapper with a porosity of 5,000 to 15,000 CU and having a length of 60 to 150 mm.

[153] Although there are no specific limitations, the draw resistance may be measured for a rod-shaped cigarette filter weighing from 300 to 1000 mg, 400 to 900 mg, 500 to 800 mg, or 600 to 700 mg.

[154] In this case, as disclosed above, the present invention makes it possible to obtain a lyocell material with a fineness within the above-mentioned ranges, in particular with a fineness that allows for providing a filtration efficiency that is generally suitable for both a conventional and an (ultra)fine filter. In addition, a cigarette filter containing such a lyocell material can be characterized by a predetermined resistance to draw.

[155] For example, if the lyocell material is used in an (ultra)fine filter (e.g. a filter rod with a circumference of 19 mm or less, in particular, the upper limit of the circumference may be, for example, 18.5 mm or less, 18 mm or less, 17.5 mm or less, 17 mm or less, or 16.5 mm or less, and the lower limit of the circumference may be, for example, 15.0 mm or more, 15.5 mm or more, 16.5 mm or more, 17.0 mm or more, 17.5 mm or more, 18.0 mm or more, or 18.5 mm or more), the overall fineness of the lyocell multifilament may be from 15,000 to 25,000 denier. In particular, the overall fineness of the lyocell multifilament used in the ultrafine filter may be 16,000 denier or more, 17,000 denier or more, 18,000 denier or more, 19,000 denier or more, 20,000 denier or more, 21,000 denier or more, 22,000 denier or more, 23,000 denier or more, or 24,000 denier or more, and may be 24,000 denier or less, 23,000 denier or less, 22,000 denier or less, 21,000 denier or less, 20,000 denier or less, 19,000 denier or less, 18,000 denier or less, 17,000 denier or less, or 16,000 denier or less. In this case, the fineness of one filament of lyocell monofilament may be, for example, 4.5 denier or more, 5.0 denier or more, 5.5 denier or more, 6.0 denier or more, 6.5 denier or more, 7.0 denier or more, or 7.5 denier or more. A cigarette filter comprising a lyocell material of such fineness may have a draw resistance of 370 mm _H2O or more, measured in accordance with KS H ISO 6565. More specifically, the cigarette filter may have a draw resistance of 380 mm _H2O or more, 390 mm _H2O or more, 400 mm _H2O or more, 410 mm _H2O or more, 420 mm _H2O or more, 430 mm _H2O or more, 440 mm _H2O or more, 450 mm _H2O or more, 460 mm _H2O or more, 470 mm _H2O or more, 480 mm _H2O or more, 490 mm _H2O or more, 500 mm _H2O or more, 510 mm _H2O or more, 520 mm _H2O or more, 530 mm _H2O or more, 540 mm _H2O or more, 550 mm H2O or more, 560 mm _H2O or more, 570 mm _H2O or more, 580 mm _H2O or more, 590 mm _H2O or more, or 600 mm _H2O or more. In this case, the upper limit of the tightening resistance may be, for example, 920 mm _H2O or less, in particular 900 mm _H2O or less, 850 mm _H2O or less, 800 mm _H2O or less, 750 mm _H2O or less, 700 mm _H2O or less, or 650 _{mm H2O} or less.

[156] In one or more embodiments of the invention, if the lyocell material is used in a conventional filter (e.g., a filter rod having a circumference of 19 mm or more, wherein the lower limit of the circumference can be, for example, 19.5 mm or more, 20.0 mm or more, 20.5 mm or more, 21.0 mm or more, 21.5 mm or more, 22.0 mm or more, 22.5 mm or more, 23.0 mm or more, 23.5 mm or more, 24.0 mm or more, 24.5 mm or more, 25 mm or more, 25.5 mm or more, 26.0 mm or more, or 26.5 mm or more, and the upper limit of the circumference can be, for example, 27.0 mm or less, 26.5 mm or less, 26.0 mm or less, 25.5 mm or less, 25.0 mm or less, 24.5 mm or less, 24.0 mm or less, 23.5 mm or less, 23.0 mm or less, 22.5 mm or less, 22.0 mm or less, 21.5 mm or less, 21.0 mm or less, 20.5 mm or less, 20.0 mm or less, or 19.5 mm or less), the lyocell multifilament may have an overall fineness of from 25,000 to 45,000 denier. Specifically, the total fineness of the lyocell multifilament used in the conventional filter may be 26,000 or more, 27,000 or more, 28,000 or more, 29,000 or more, 30,000 or more, 31,000 or more, 32,000 or more, 33,000 or more, 34,000 or more, 35,000 or more, 36,000 or more, 37,000 or more, 38,000 or more, 39,000 or more, 40,000 or more, 41,000 or more, 42,000 or more, 43,000 or more, or 44,000 or more, and may be 44,000 or less, 43,000 or less, 42 000 or less, 41,000 or less, 40,000 or less, 39,000 or less, 38,000 or less, 37,000 or less, 36,000 or less, 35,000 or less, 34,000 or less, 33,000 or less, 32,000 or less, 31,000 or less, 30,000 or less, 29,000 or less, 28,000 or less, 27,000 or less, or 26,000 or less. In this case, the fineness of one fiber of the lyocell monofilament may be, for example, 5.0 denier or less, 4.5 denier or less, 4.5 denier or less, 4.0 denier or less, 3.5 denier or less, 3.0 denier or less, 2.5 denier or less, or 2.0 denier or less. A cigarette filter containing lyocell material of such fineness may have a draw resistance of 185 mm _H2O or more, measured in accordance with KS H ISO 6565. More specifically, the cigarette filter may have a draw resistance of 190 mm _H2O or more, 200 mm _H2O or more, 210 mm _H2O or more, 220 mm _H2O or more, 230 mm _H2O or more, 240 mm _H2O or more, 250 mm _H2O or more, 260 mm _H2O or more, 270 mm _H2O or more, 280 mm _H2O or more, 290 mm _H2O or more, 300 mm _H2O or more, 310 mm _H2O or more, 320 mm _H2O or more, 330 mm _H2O or more, 340 mm _H2O or more, 350 mm _H2O or more, 360 mm _H2O or more, or 370 mm _H2O or more. In this case, the upper limit of tightening resistance may be, for example, 500 mm _H2O or less, 450 mm _H2O or less, or 400 mm _H2O or less.

[157] A cigarette filter with this draw resistance value is capable of providing uniform concentration and high efficiency of smoke filtration when the user smokes a cigarette.

[158] In one or more embodiments, the present invention relates to a cigarette filter. The cigarette filter may comprise a lyocell material with a modified cross-section, wherein the lyocell material may be the same as disclosed above.

[159] More specifically, the lyocell material with a modified cross-section included in the cigarette filter may be a crimped cord made by crimping a lyocell multifilament. In addition, the lyocell multifilament may comprise a monofilament with a modified cross-section and have a total fineness of from 15,000 denier to 45,000 denier, and the monofilaments constituting the lyocell multifilament may have a single fiber fineness of from 1.5 denier to 8.0 denier. In addition, the modified cross-section of the monofilament may have at least three projections, wherein each projection may have a modified shape factor of 0.6 or more and a width factor of from 0.5 to 2.0. The specific values of these factors are similar to those disclosed above. In addition, as disclosed above, the modified shape factor and the width factor can be calculated as follows:

[160] <Formula 1>

[161] Modified form factor = L/W

[162] <Formula 2>

[163] Width ratio = W ₁ /W ₂

[164] where in formulas 1 and 2, L expresses the length of each of the three projections, the length being calculated as the distance from the center of the straight line connecting the two points where one projection intersects the two projections immediately adjacent to the one projection to the end point of one projection. In addition, W expresses the width of each of the three projections, the width being calculated as the arithmetic mean of the width (W ₁ ) of the projection at the point corresponding to 10% of the length L and the width (W ₂ ) of the projection at the point corresponding to 90% of the length L. A detailed description is given below.

[165] In one embodiment of the invention, the lyocell material may be a crimped tow produced by feeding the tow into a crimping machine capable of forming crimps under conditions corresponding to a crimp factor expressed by <Formula 1>:

[166] <Formula 1>

[167] 1.01 ≤ tortuosity coefficient ≤ 1.30

[168] in which, according to formula 1, the crimping coefficient is calculated as V ₁ /V ₀ , where V ₀ is the speed of movement of the thread before feeding the multifilament into the crimping machine, and V ₁ is the speed of passage of the thread captured by the roller in the crimping machine.

[169] In one embodiment of the invention, the crimped rope may contain from 20 to 50 crimps per inch. A detailed description thereof is provided below.

[170] In one embodiment of the invention, the lyocell material included in the cigarette filter may be manufactured using the above-disclosed method for manufacturing the lyocell material. In particular, the lyocell material may be manufactured using all processes including spinning, coagulation, washing, oiling, and crimping.

[171] In one embodiment, the cigarette filter may further comprise a wrapper. That is, the cigarette filter may comprise a lyocell material; and a wrapper surrounding the lyocell material. The detailed description of the wrapper is similar to that disclosed above and will therefore be omitted.

[172] In one embodiment of the invention, the cigarette filter may have a draw resistance of 185 mm H ₂ O or more, measured in accordance with KS H ISO 6565. More specifically, the draw resistance of the cigarette filter may be 190 mm H ₂ O or more, 200 mm H ₂ O or more, 210 mm H ₂ O or more, 220 mm H ₂ O or more, 230 mm H ₂ O or more, 240 mm H ₂ O or more, 250 mm H ₂ O or more, 260 mm H ₂ O or more, 270 mm H ₂ O or more, 280 mm H ₂ O or more, 290 mm H ₂ O or more, 300 mm H ₂ O or more, 310 mm H ₂ O or more, 320 mm H ₂ O or more, 330 mm H ₂ O or more, 340 mm _H2O or more, 350 mm _H2O or more, 360 mm H2O or more, 370 mm _H2O or more, 380 mm _H2O or more, 390 mm _H2O or more, 400 mm _H2O or more, 410 mm _H2O or more, 420 mm _H2O or more, 430 mm _H2O or more, ₄₄₀ mm _H2O or more, or 450 mm _H2O or more. In addition, the upper limit of tightening resistance may be, for example, 920 mm _H2O or less. In particular, the upper limit of the tightening resistance may be, for example, 910 mm _H2O or less, 900 mm _H2O or less, 890 mm _H2O or less, 880 mm H2O or less, 870 mm _H2O or less, 860 mm _H2O or less, 850 mm _H2O or less, 840 mm _H2O or less, 830 mm _H2O or less, 820 mm _H2O or less, 810 mm _H2O or less, 800 mm _H2O or less, 750 mm _H2O or less, 650 mm _H2O or less, 600 mm _H2O or less, 550 mm _H2O or less, 500 mm _H2O or less, 450 mm _H2O or _less , 400 mm _H2O or less, and for example, 390 mm _H2O or less, 380 mm _H2O or less, 370 mm H2O or less, 360 mm _H2O or less, 350 mm _H2O or less, 340 mm _H2O or less, 330 mm _H2O or less, 320 mm _H2O or less, 310 mm _H2O or less, 300 mm _H2O or less, 290 mm _H2O or less, 280 mm _H2O or less, 270 mm _H2O or less, 260 mm _H2O or less, 250 mm _H2O or less, 240 mm _H2O or less, 230 mm _H2O or less, 220 mm _H2O or less, 210 mm _H2O or less, or 200 mm _H2O or less _.

[173] Although there is no particular limitation, the draw resistance may be measured for a filter rod with a circumference of 10 to 30 mm or 15 to 27 mm. The circumference of a cigarette filter may be determined by the number of twists of the tow, the quality of the tow (for example, the uniformity of the shape of the twist), etc., and the draw resistance of a cigarette filter may be determined by the thinness and cross-section.

[174] Although there are no specific limitations, the draw resistance may be measured for a filter rod containing a wrapper with a porosity of 5,000 to 15,000 CU and having a length of 60 to 150 mm.

[175] Although there are no specific limitations, the draw resistance may be measured for a rod-shaped cigarette filter weighing from 300 to 1000 mg, 400 to 900 mg, 500 to 800 mg, or 600 to 700 mg.

[176] In this case, as disclosed above, the present invention makes it possible to obtain a lyocell material with a fineness within the above-mentioned ranges, in particular with a fineness that allows for providing a filtration efficiency that is generally suitable for both a normal and an (ultra)fine filter. In addition, a cigarette filter containing such a lyocell material can be characterized by a predetermined resistance to draw.

[177] For example, if the lyocell material is used in an (ultra)fine filter (e.g. a filter rod with a circumference of 19 mm or less, in particular, the upper limit of the circumference may be, for example, 18.5 mm or less, 18 mm or less, 17.5 mm or less, 17 mm or less, or 16.5 mm or less, and the lower limit of the circumference may be, for example, 15.0 mm or more, 15.5 mm or more, 16.5 mm or more, 17.0 mm or more, 17.5 mm or more, 18.0 mm or more, or 18.5 mm or more), the overall fineness of the lyocell multifilament may be from 15,000 to 25,000 denier. In particular, the overall fineness of the lyocell multifilament used in the ultrafine filter may be 16,000 denier or more, 17,000 denier or more, 18,000 denier or more, 19,000 denier or more, 20,000 denier or more, 21,000 denier or more, 22,000 denier or more, 23,000 denier or more, or 24,000 denier or more, and may be 24,000 denier or less, 23,000 denier or less, 22,000 denier or less, 21,000 denier or less, 20,000 denier or less, 19,000 denier or less, 18,000 denier or less, 17,000 denier or less, or 16,000 denier or less. In this case, the fineness of one filament of lyocell monofilament may be, for example, 4.5 denier or more, 5.0 denier or more, 5.5 denier or more, 6.0 denier or more, 6.5 denier or more, 7.0 denier or more, or 7.5 denier or more. A cigarette filter comprising a lyocell material of such fineness may have a draw resistance of 370 mm _H2O or more, measured in accordance with KS H ISO 6565. More specifically, the cigarette filter may have a draw resistance of 380 mm _H2O or more, 390 mm _H2O or more, 400 mm _H2O or more, 410 mm _H2O or more, 420 mm _H2O or more, 430 mm _H2O or more, 440 mm _H2O or more, 450 mm _H2O or more, 460 mm _H2O or more, 470 mm _H2O or more, 480 mm _H2O or more, 490 mm _H2O or more, 500 mm _H2O or more, 510 mm _H2O or more, 520 mm _H2O or more, 530 mm _H2O or more, 540 mm _H2O or more, 550 mm H2O or more, 560 mm _H2O or more, 570 mm _H2O or more, 580 mm _H2O or more, 590 mm _H2O or more, or 600 mm _H2O or more. In this case, the upper limit of the tightening resistance may be, for example, 920 mm _H2O or less, in particular 900 mm _H2O or less, 850 mm _H2O or less, 800 mm _H2O or less, 750 mm _H2O or less, 700 mm _H2O or less, or 650 _{mm H2O} or less.

[178] In one or more embodiments, when the lyocell material is used in a conventional filter (e.g., a filter rod with a circumference of 19 mm or more), the lower limit of the circumference may be, for example, 19.5 mm or more, 20.0 mm or more, 20.5 mm or more, 21.0 mm or more, 21.5 mm or more, 22.0 mm or more, 22.5 mm or more, 23.0 mm or more, 23.5 mm or more, 24.0 mm or more, 24.5 mm or more, 25 mm or more, 25.5 mm or more, 26.0 mm or more, or 26.5 mm or more, and the upper limit of the circumference may be, for example, 27.0 mm or less, 26.5 mm or less, 26.0 mm or less, 25.5 mm or less, 25.0 mm or less, 24.5 mm or less, 24.0 mm or less, 23.5 mm or less, 23.0 mm or less, 22.5 mm or less, 22.0 mm or less, 21.5 mm or less, 21.0 mm or less, 20.5 mm or less, 20.0 mm or less, or 19.5 mm or less), the lyocell multifilament may have an overall fineness of from 25,000 to 45,000 denier. Specifically, the total fineness of the lyocell multifilament used in the conventional filter may be 26,000 or more, 27,000 or more, 28,000 or more, 29,000 or more, 30,000 or more, 31,000 or more, 32,000 or more, 33,000 or more, 34,000 or more, 35,000 or more, 36,000 or more, 37,000 or more, 38,000 or more, 39,000 or more, 40,000 or more, 41,000 or more, 42,000 or more, 43,000 or more, or 44,000 or more, and may be 44,000 or less, 43,000 or less, 42 000 or less, 41,000 or less, 40,000 or less, 39,000 or less, 38,000 or less, 37,000 or less, 36,000 or less, 35,000 or less, 34,000 or less, 33,000 or less, 32,000 or less, 31,000 or less, 30,000 or less, 29,000 or less, 28,000 or less, 27,000 or less, or 26,000 or less. In this case, the fineness of one fiber of the lyocell monofilament may be, for example, 5.0 denier or less, 4.5 denier or less, 4.5 denier or less, 4.0 denier or less, 3.5 denier or less, 3.0 denier or less, 2.5 denier or less, or 2.0 denier or less. A cigarette filter containing lyocell material of such fineness may have a draw resistance of 185 mm _H2O or more, measured in accordance with KS H ISO 6565. More specifically, the cigarette filter may have a draw resistance of 190 mm _H2O or more, 200 mm _H2O or more, 210 mm _H2O or more, 220 mm _H2O or more, 230 mm _H2O or more, 240 mm _H2O or more, 250 mm _H2O or more, 260 mm _H2O or more, 270 mm _H2O or more, 280 mm _H2O or more, 290 mm _H2O or more, 300 mm _H2O or more, 310 mm _H2O or more, 320 mm _H2O or more, 330 mm _H2O or more, 340 mm _H2O or more, 350 mm _H2O or more, 360 mm _H2O or more, or 370 mm _H2O or more. In this case, the upper limit of tightening resistance may be, for example, 500 mm _H2O or less, 450 mm _H2O or less, or 400 mm _H2O or less.

[179] A cigarette filter with this draw resistance value is capable of providing uniform concentration and high efficiency of smoke filtration when the user smokes a cigarette.

[180] Beneficial effects of the invention

[181] According to the present invention, there is provided a lyocell material for a cigarette filter capable of replacing cellulose acetate, which is widely used in the market, and a cigarette filter containing the lyocell material. In particular, the present invention advantageously provides not only excellent biodegradability but also excellent filter manufacturing processability and excellent cigarette properties (e.g., draw resistance).

[182] Description of drawings

[183] FIG. 1 is a diagram illustrating a cross-sectional shape, as well as a modified shape factor and a width factor in predetermined ranges for a lyocell fiber with a modified cross-section according to one embodiment of the present invention.

[184] FIG. 2 is an optical image of a cross-section of a lyocell material manufactured in accordance with Example 1.

The best option

[185] Principle of the invention

[186] The present invention will be further described in detail with reference to the following examples. However, the following examples are merely illustrative in nature and do not limit the scope of the present invention.

[187] Examples and comparative examples

[188] Lyocell materials are manufactured using the technology disclosed in the examples and comparative examples below. Terms not explicitly mentioned in the text are included within the scope of legal protection of the above disclosure.

[189] Example 1

[190] A pulp having a weight average degree of polymerization (DPw) of 820 containing 93.9% alpha cellulose was mixed with an NMMO/ _H2O solvent containing 0.01% by weight of propyl gallate to obtain a spinning solution for producing a tow for a cigarette filter with a concentration of 11% by weight. Then, the spinning material was kept at a temperature of 110°C in a spinning nozzle to obtain a Y-shaped cross section and spun by adjusting the discharge amount and the spinning speed so that the single fiber fineness of the filaments was adjusted to 3.45 denier.

[191] The spinning solution in the form of filaments exiting the spinning nozzle was fed into a coagulating solution (a coagulating solution containing 75 wt.% water and 25 wt.% NMMO and used at a temperature of about 25 °C) contained in a coagulation bath through an air gap zone. In this case, the spinning solution was coagulated predominantly in the air gap zone by means of cooling air at a temperature of 8 °C and an air flow rate of 200 ^Nm3 /h. In addition, the concentration of the coagulating solution was continuously monitored using a sensor and a refractometer.

[192] The pre-coagulated lyocell yarns were then washed with water. Specifically, the yarns were fed to a draw roll to remove the NMMO remaining in the yarns using a washing solution sprayed by a washing device. The washed yarns were then immersed in a bath with an oil concentration of 2 wt%.

[193] Then, the yarns were treated with a pressure of about 2 kgf/ ^cm2 by a roller installed in the discharge section of the bath, and fed to a crimping machine to form crimps. Specifically, a crimping ratio (crimping ratio) was set to 1.1, and a tow was produced by supplying steam to a steam box at a pressure of 0.5 kgf/ ^cm2 , setting the roller pressure of the crimping machine to 2.5 kgf/ ^cm2 , and setting the pressure of the knife device to 0.5 kgf/ ^cm2 . In this case, the crimping ratio was calculated as described above.

[194] The resulting tow was subjected to secondary oiling to prevent static charge and provide flexibility, and immediately after secondary oiling, the resulting tow was passed through a continuous dryer set at 120°C to obtain a dry finished tow. The overall fineness of the tow corresponds to that indicated in Table 1.

[195] Example 2

[196] The lyocell tow for the cigarette filter was made similarly to Example 1, except that the fineness of one fiber of the threads was brought to 4.6 denier. The overall fineness of the tow corresponds to that indicated in Table 1.

[197] Example 3

[198] The lyocell tow for the cigarette filter was made similarly to Example 1, except that the fineness of one fiber of the threads was brought to 5.55 denier. The overall fineness of the tow corresponds to that indicated in Table 1.

[199] Example 4

[200] The lyocell tow for the cigarette filter was made similarly to Example 1, except that the fineness of one fiber of the threads was brought to 6.98 denier. The overall fineness of the tow corresponds to that indicated in Table 1.

[201] Comparative example 1

[202] The lyocell tow for the cigarette filter was made similarly to Example 1, except that the fineness of one fiber of the threads was brought to 0.55 denier. The overall fineness of the tow corresponds to that indicated in Table 1.

[203] Comparative example 2

[204] The lyocell tow for the cigarette filter was made similarly to Example 1, except that the fineness of one fiber of the threads was brought to 1.12 denier. The overall fineness of the tow corresponds to that indicated in Table 1.

[205] Comparative example 3

[206] The lyocell tow for the cigarette filter was made similarly to Example 1, except that the fineness of one fiber of the threads was brought to 1.43 denier. The overall fineness of the tow corresponds to that indicated in Table 1.

[207] Comparative example 4

[208] The lyocell tow for the cigarette filter was made similarly to Example 1, except that the fineness of one fiber of the threads was brought to 8.85 denier. The overall fineness of the tow corresponds to that indicated in Table 1.

[209] Comparative example 5

[210] A lyocell tow for a cigarette filter was made similar to Example 1 except that the fineness of one fiber of the threads was brought to 9.94 denier. The overall fineness of the tow corresponds to that indicated in Table 1.

[211] Evaluation or measurement of harnesses according to Examples and Comparative Examples

[212] The following parameters were measured or estimated for each of the Examples and Comparative Examples, and the results were summarized in Table 1.

[213] Denier

[214] For the measurement, a 2 m sample of the tow was taken and kept in a room with a constant temperature of 20 °C and humidity of 65%. After securing one end of the stabilized tow, a 2 kg weight was attached to the other end. After holding (stabilizing) the tow stretched under the weight for 5 seconds, the sample was cut to a size of 90 cm and weighed (total fineness). The tow fineness was converted to the value of measured mass × 10,000 in accordance with the denier conversion method. The fineness of one fiber is calculated by dividing the total fineness by the number of strands in the threads.

[215] 2. Number of twists

[216] The crimps were measured according to KS K 0326 standards. Specifically, 20-strand bundle samples with intact crimps were collected and each strand was bonded to a pre-prepared sheet of glossy paper (at 25 mm intervals) with 4% - 5% amyl acetate celluloid adhesive with an elongation of 25±5% relative to the length of one fibre, and then left until the adhesive dried.

[217] The number of crimps of each specimen was calculated by applying a primary load of 1.96/1000 cN (=2 mgf) per 1 De to each strand using a crimp tester, and the number of crimps per 25 mm was determined. The upper and lower limits of the number of crimps measured for the 20 strands were then recorded.

[218] 3. Measurement of the modified shape coefficient of the protrusion

[219] A small amount of fiber bundle was collected, rolled and thinned with black cotton, inserted into the hole in the cross-sectional plate, and cut with a razor blade without applying pressure to the cross-section. Then, the cross-sectional sections were enlarged (200x magnification) under an optical microscope (BX51, Olympus), and photographed with a digital camera.

[220] Using the Olympus Soft Imaging Solution program, L (protrusion length), W (protrusion width), circumference length, etc. of the modified cross-section of the measured thread were analyzed from the images of the fiber cross-section. In this case, L, W, and the modified shape coefficient were calculated in the same way as described earlier.

[221] 4. Measuring the ledge width ratio

[222] The samples were prepared in the same manner as the measurement of the modified shape factor disclosed above. Then, using the Olympus Soft Imaging Solution software to obtain images of the fiber cross section, the width of the protrusion (W ₁ ) at a point corresponding to 10% of the base length (length (L) measured taking into account the modified shape factor) to be measured and the width of the protrusion (W ₂ ) at a point corresponding to 90% of the base length (length L measured taking into account the modified shape factor) from the center of the cross section were measured, and the width ratios were calculated.

[223] 5. Spinning ability

[224] After unloading the spinning solution from the spinning mechanism, the completion or absence of a cut on the surface of the spinning mechanism and the number of cuts were recorded every hour. Depending on the number of cuts completed in 24 hours, the following assessments were made:

[225] Good: No cuts for 24 hours

[226] Moderate: One to four cuts in 24 hours

[227] Not measurable: at least 5 cuts within 24 hours.

[228] 6. Draw resistance and cigarette filter circumference

[229] Cigarette filter rods (rod weight: 650 mg) were prepared using the tows produced in the above Examples and Comparative Examples. Specifically, the lyocell tow according to each of the Examples and Comparative Examples was wrapped with a wrapper (porous paper with 6,500 CU) to produce a cylindrical filter rod having an axial length of 120 mm and a circumferential length according to the following table.

[230] In addition, the tightening resistance was measured according to KS H ISO 6565 standards, and the tightening resistance of each bar was measured using a circle gauge.

[231] [Table 1]

Fineness of one fiber
tourniquet Spinning ability Quantity
twists and turns
(pcs./
inch) General subtlety
tourniquet Modified form coefficient
(Formula 1) Width coefficient
(Formula 2) Tightening resistance
filters
(mm _H2O ) Circle
(mm) Example 1 3.45 Fine 34-38 35400 1.51 1.54 305 24.2
(ordinary) Example 2 4.6 Fine 30-34 30700 2.08 1.36 220 24.4
(ordinary) Example 3 5.55 Fine 28-32 23000 2.23 1.22 410 18.8
(thin) Example 4 6.98 Fine 30-34 19700 2.53 1,12 520 16.6
(ultra thin) Comparative example 1 0.55 Defective (unable to produce continuously) - - 0.38 2.16 Unmeasurable
(making a tourniquet is impossible) - Comparative example 2 1,12 Fine 40-48 46500 1.05 2.54 170 23.6
(ordinary) Comparative example 3 1.43 Fine 38-42 45500 1.16 2.47 160 23.8
(ordinary) Comparative example 4 8.55 Fine 22-30 14800 2.72 2.38 360 17.1
(ultra thin) Comparative example 5 9.94 Fine 18-28 13400 2.84 2.16 340 17.0
(ultra thin)

[232] According to Table 1, it was confirmed that the tows according to Examples of the present invention have a satisfactory predetermined shape and a satisfactory thinness within a predetermined range and are capable of increasing the tightening resistance.

[233] However, in the case of Comparative Example 1, the spinning conditions were not suitable, so that the tow could not be produced, and the characteristics of the filters (draw resistance) could not be determined. Furthermore, in the case of Comparative Examples 2 to 5, in which the shape and fineness of the modified cross-sections were different from those of the Examples, it was confirmed that both the normal filter (with a circumference of 23 to 24.5 mm) and the (ultra)fine filter (with a circumference of 16 to 19 mm) had lower draw resistance than the Examples with the corresponding circumferences.

Claims (65)

1. A method for producing a lyocell material with a modified cross-section for a cigarette filter, comprising: spinning a lyocell dope using a spinning mechanism capable of forming a modified cross-section having at least three projections; coagulation of the spun lyocell spinning solution to obtain a lyocell multifilament; oiling of lyocell multifilament; and forming crimps by feeding the lyocell multifilament, which has undergone oiling, into a crimping machine so that the lyocell multifilament is exposed to steam and pressure, wherein the lyocell multifilament comprises a monofilament with a modified cross-section, the modified cross-section has at least three projections, each of at least three projections has a modified shape coefficient (K _s ) of 0.6 or more, calculated as: K _s = L/W and a width coefficient (K _w ) from 0.5 to 2.0, calculated as: K _w = W ₁ /W ₂ , where: L is the length of each of the three projections, which is calculated as the distance from the center of the straight line connecting the two points where one projection intersects the two projections immediately adjacent to one projection, to the end point of that one projection; W is the width of each of the three protrusions, where the width is calculated as the arithmetic mean of the width of the protrusion (W ₁ ) at the point corresponding to 10% of the length (L) and the width of the protrusion (W ₂ ) at the point corresponding to 90% of the length (L); and lyocell multifilament has a total fineness from 15,000 denier to 45,000 denier, and the monofilaments that make up lyocell multifilament have a single fiber fineness from 1.5 denier to 8.0 denier. 2. The method according to claim 1, wherein when forming the curls, the pressure of the roller is applied to the lyocell multifilament, and the formation of the curls is performed until the curl coefficient (K _c ) is met, expressed as 1.01 ≤ K _c ≤ 1.30 and calculated as: K _c = V ₁ /V ₀ , where: V ₀ - the speed of the thread before feeding the multifilament, which has undergone oiling, into the crimping machine; V ₁ - the speed of passage of the thread captured by the roller in the machine for imparting crimp. 3. The method according to claim 1, wherein a tow containing from 20 to 50 twists per inch is obtained. 4. The method of claim 1, wherein the lyocell multifilament has a total fineness of from 15,000 to 25,000 denier. 5. The method of claim 1, wherein the lyocell multifilament has a total fineness of from 25,000 to 45,000 denier. 6. A lyocell material with a modified cross-section for a cigarette filter, wherein the lyocell material is a crimped cord made by crimping a lyocell multifilament, the lyocell multifilament has a total fineness of 15,000 to 45,000 denier, the monofilaments that make up the lyocell multifilament have a single fiber fineness of 1.5 denier to 8.0 denier, the lyocell multifilament comprises a monofilament with a modified cross-section, the modified cross-section has at least three protrusions, and each of the protrusions has a modified shape coefficient (K _s ) of 0.6 or more, calculated as: K _s = L/W and a width coefficient (K _w ) from 0.5 to 2.0, calculated as: K _w = W ₁ /W ₂ , where: L is the length of each of the three projections, which is calculated as the distance from the center of the straight line connecting the two points where one projection intersects the two projections immediately adjacent to one projection, to the end point of that one projection; W is the width of each of the three protrusions, where the width is calculated as the arithmetic mean of the width of the protrusion (W ₁ ) at the point corresponding to 10% of the length (L) and the width of the protrusion (W ₂ ) at the point corresponding to 90% of the length (L). 7. The lyocell material of claim 6, wherein the lyocell material is produced by feeding into a crimping machine capable of forming crimps under conditions corresponding to a crimp coefficient (K _c ) expressed as 1.01 ≤ K _c ≤ 1.30 and calculated as: K _c = V ₁ /V ₀ , where: V ₀ - the speed of the thread before feeding the multifilament into the machine to impart crimp; V ₁ - the speed of passage of the thread captured by the roller in the machine for imparting crimp. 8. The lyocell material of claim 6, wherein the lyocell material contains from 20 to 50 crimps per inch. 9. The lyocell material of claim 6, wherein the lyocell multifilament has a total fineness of from 15,000 to 25,000 denier. 10. The lyocell material of claim 6, wherein the lyocell multifilament has a total fineness of from 25,000 to 45,000 denier. 11. A method for producing a cigarette filter comprising a lyocell material with a modified cross-section for a cigarette filter, the method comprising: spinning a lyocell dope using a spinning mechanism capable of forming a modified cross-section having at least three projections; coagulation of the spun lyocell spinning solution to obtain a lyocell multifilament; oiling of lyocell multifilament; forming crimps by feeding the lyocell multifilament, which has undergone oiling, into a crimping machine so that the lyocell multifilament is exposed to steam and pressure; and manufacturing a filter using a twisted bundle, wherein the lyocell multifilament comprises a monofilament with a modified cross-section, the modified cross-section has at least three projections, each of the protrusions has a modified form coefficient (K _s ) of 0.6 or more, calculated as: K _s = L/W and a width coefficient (K _w ) from 0.5 to 2.0, calculated as: K _w = W ₁ /W ₂ , where: L is the length of each of the three projections, which is calculated as the distance from the center of the straight line connecting the two points where one projection intersects the two projections immediately adjacent to one projection, to the end point of that one projection; W is the width of each of the three projections, where the width is calculated as the arithmetic mean of the projection width (W ₁ ) at a point corresponding to 10% of the length (L) and the projection width (W ₂ ) at a point corresponding to 90% of the length (L); and Lyocell multifilament has an overall fineness of 15,000 denier to 45,000 denier, and the monofilaments that make up lyocell multifilament have a single filament fineness of 1.5 denier to 8.0 denier. 12. The method according to claim 11, wherein when forming the curls, the pressure of the roller is applied to the lyocell multifilament, and the formation of the curls is performed until the curl coefficient (Kc) is met, expressed as 1.01 ≤ K _c ≤ 1.30 and calculated as: K _c = V ₁ /V ₀ , where: V ₀ - the speed of the thread before feeding the multifilament into the machine to impart crimp; V ₁ - the speed of passage of the thread captured by the roller in the machine for imparting crimp. 13. The method of claim 11, wherein the tow comprises from 20 to 50 twists per inch. 14. A cigarette filter comprising a lyocell material with a modified cross-section, wherein the lyocell material with a modified cross-section is a crimped cord made by crimping a lyocell multifilament, the lyocell multifilament has a total fineness of 15,000 to 45,000 denier, the monofilaments that make up the lyocell multifilament have a single fiber fineness of 1.5 denier to 8.0 denier, the lyocell multifilament comprises a monofilament with a modified cross-section, the modified cross-section has at least three protrusions, and each of the at least three protrusions has a modified shape coefficient (K _s ) of 0.6 or more, calculated as: K _s = L/W and a width coefficient (K _w ) from 0.5 to 2.0, calculated as K _w = W ₁ /W ₂ , where L is the length of each of the three projections, which is calculated as the distance from the center of the straight line connecting the two points where one projection intersects the two projections immediately adjacent to this one projection, to the end point of one projection; W is the width of each of the three protrusions, where the width is calculated as the arithmetic mean of the width (W ₁ ) of the protrusion at the point corresponding to 10% of the length (L) and the width (W ₂ ) of the protrusion at the point corresponding to 90% of the length (L). 15. A cigarette filter according to claim 14, wherein the lyocell material is produced by feeding it into a crimping machine capable of forming crimps under conditions corresponding to a crimping coefficient (K _c ) expressed as 1.01 ≤ K _c ≤ 1.30 and calculated as: K _c = V ₁ /V ₀ , where: V ₀ - the speed of the thread before feeding the multifilament into the machine to impart crimp; V ₁ - the speed of passage of the thread captured by the roller in the machine for imparting crimp). 16. The cigarette filter of claim 14, wherein the twisted cord comprises from 20 to 50 twists per inch.