Lyocell material for cigarette filters and method for manufacturing the same

Abstract

The present invention relates to a lyocell material for a cigarette filter and a manufacturing method thereof, which is capable of securing optimal processability required for manufacturing a cigarette filter by setting an optimal denier range of lyocell tow, wherein the lyocell tow is imparted with a curling capable of realizing filter properties equivalent to those of cellulose acetate currently used for a cigarette filter, and due to excellent biodegradability, environmental pollution factors caused by discarded cigarette butts can be reduced.

Description

Technical Field

[0001] Cross-reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2021-0129846, filed on September 30, 2021, and Korean Patent Application No. 10-2022-0118769, filed on September 20, 2022, the entire contents of which are incorporated herein by reference.

[0003] This invention relates to a lyocell material for cigarette filters and its manufacturing method. Background Technology

[0004] Typical cigarette filters contain cellulose acetate tow, obtained by acetylation of cellulose extracted from wood pulp.

[0005] In addition, cigarette filters are assembled into cigarette products and distributed to consumers for smoking, and are ultimately discarded after smoking. Furthermore, some cigarette filters are discarded directly by cigarette filter manufacturers as manufacturing waste. These cigarette filters are then recycled as waste and disposed of in landfills. In some cases, cigarette filters are not recycled as waste but remain in the natural environment.

[0006] Therefore, various methods have been proposed for manufacturing biodegradable cigarette filters, including adding additives made of biodegradable polymers to increase the decomposition rate of cellulose acetate, or using cellulose acetate with a low degree of substitution to improve biodegradability, or using composite materials of highly biodegradable polymers such as polyhydroxybutyrate (PHB) / polyvinyl butyral (PVB) and starch as filter tow raw materials.

[0007] Furthermore, in recent years, research has been underway to use environmentally friendly materials to replace cellulose acetate tow in order to protect the natural environment and reduce costs. For example, the development of tows using lyocell fibers is underway, which, unlike cellulose acetate, involves the fibrillation of cellulose itself.

[0008] However, a material has not yet been developed that can reduce environmental pollution to the required level while meeting filter performance comparable to cellulose acetate, an existing cigarette filter material. Summary of the Invention

[0009] Technical issues

[0010] One embodiment of the present invention aims to provide a lyocell material for cigarette filters and a method for manufacturing the same, which can achieve cigarette filter performance comparable to existing cellulose acetate (CA) products by utilizing lyocell material.

[0011] Furthermore, one embodiment of the present invention provides a lyocell material for cigarette filters and a method for manufacturing the same, wherein the lyocell material can reduce environmental pollution caused by the waste from cellulose acetate cigarette butts.

[0012] Technical solution

[0013] In this specification, according to one embodiment, a method for manufacturing a lyocell material for cigarette filters is provided, comprising the following steps:

[0014] (S1) Spinning is performed on a Lyocell spinning solution containing cellulose slurry and an aqueous solution of N-methylmorpholine-N-oxide (NMMO);

[0015] (S2) The lyocell spinning solution after spinning is solidified to obtain lyocell multifilament;

[0016] (S3) The obtained Lyocell multifilament is washed with water;

[0017] (S4) Treat the washed Lyocell multifilament with an oiling agent;

[0018] (S5) The Lyocell multifilament treated with the oiling agent is crimped to obtain a crimped tow; and

[0019] (S6) Dry the crimped filament bundle.

[0020] The step of obtaining crimped filament bundles includes: crimping the oil-treated Lyocell multifilaments in a manner that satisfies a crimping machine draw ratio of 1.01 to 1.3 times, calculated by the following formula 1.

[0021] The crimped filaments have a thickness range of 25,000 to 45,000 niers (De):

[0022] Formula 1:

[0023] Drafting machine draw ratio = V1 / V0

[0024] In Equation 1, V0 is the speed at which the oiled Lyocell multifilament is fed into the crimping machine (Crimper M / C), and V1 is the rotational speed of the roller in the crimping machine (Crimper M / C) used to crimp the oiled Lyocell multifilament.

[0025] Furthermore, according to another embodiment, this specification provides a lyocell material for cigarette filters, comprising a crimped tow formed from lyocell multifilaments obtained by spinning a lyocell spinning solution containing cellulose slurry and an aqueous solution of N-methylmorpholine-N-oxide (NMMO).

[0026] The crimped filament bundle is a Lyocell filament bundle with a thickness range of 25,000 to 45,000 deniers.

[0027] Furthermore, this specification provides a cigarette filter comprising the aforementioned lyocell material for cigarette filters.

[0028] The following will describe in detail the embodiment of the invention, the lyocell material for cigarette filters, and the method for manufacturing the same.

[0029] Unless otherwise expressly stated in this specification, the terminology used herein is for reference only in particular embodiments and does not limit the invention.

[0030] The singular form used in this specification includes the plural form, unless the phrase explicitly indicates the opposite meaning.

[0031] As used in this specification, the word "comprising" refers to a particular characteristic, region, integer, step, operation, element, and / or component, and does not exclude the presence or addition of other particular characteristics, regions, integers, steps, operations, elements, components, and / or groups.

[0032] In this specification, the terms "at least one" or "one or more" should be understood to include all possible combinations from one or more related items.

[0033] The present invention will be described in detail below.

[0034] Methods for manufacturing Lyocell materials

[0035] According to one embodiment of the invention, a method for manufacturing lyocell material for cigarette filters can be provided, comprising the following steps: (S1) spinning a lyocell spinning solution containing cellulose slurry and an aqueous solution of N-methylmorpholine-N-oxide (NMMO); (S2) coagulating the lyocell spinning solution after spinning to obtain lyocell multifilament; (S3) washing the obtained lyocell multifilament with water; (S4) treating the washed lyocell multifilament with an oiling agent; (S5) crimping the lyocell multifilament treated with the oiling agent to obtain crimped filaments. (S6) Drying the crimped filament bundle, wherein the step of obtaining the crimped filament bundle includes: crimping the oil-treated lyocell multifilament in such a way that the crimping machine draw ratio calculated by the following formula satisfies 1.01 to 1.3 times, the crimped filament bundle having a thickness range of 25,000 to 45,000 deniers:

[0036] Formula 1:

[0037] Drafting machine draw ratio = V1 / V0

[0038] In Equation 1, V0 is the speed at which the oiled Lyocell multifilament is fed into the crimping machine (Crimper M / C), and V1 is the rotational speed of the roller of the crimping machine used to crimp the oiled Lyocell multifilament.

[0039] The purpose of this invention is to provide a lyocell material for cigarette filters and a method for manufacturing the same, which can replace traditional cigarette filter materials by manufacturing cigarette filter tows incorporating lyocell, which has excellent biodegradability.

[0040] Furthermore, the object of the present invention is to manufacture cigarette filter tows with excellent biodegradability and comparable performance to existing cellulose acetate products by using lyocell material.

[0041] Specifically, in the manufacture of lyocell cigarette filter tow, the present invention sets the optimal fineness range of the lyocell tow by adjusting the draw ratio of the crimping machine during the crimping process, thereby ensuring optimal processability for manufacturing cigarette filters. In this process, the lyocell tow is given a crimp that achieves filter properties comparable to those of cellulose acetate currently used as cigarette filters.

[0042] According to one embodiment of the present invention, in the curling process, the lyocell cigarette filter tow can be applied to the filaments with a process draw condition of 1.01 to 1.3 times to impart uniform curling.

[0043] During the curling process, the draft ratio in the curling machine can be calculated according to the following formula 1.

[0044] Formula 1:

[0045] Crimper draw ratio = V1 / V0

[0046] In Formula 1, V0 is the speed before being fed into the crimping machine (Crimper M / C), and V1 is the rotational speed of the rollers of the crimping machine used to crimp the oiled Lyocell multifilament.

[0047] The term Crimper M / C refers to a crimp machine.

[0048] At this time, if the draw ratio of the crimping machine is less than 1.01 times, the tension of the filament bundle fed into the crimping machine is unstable, resulting in uneven crimping. If it is equal to or greater than 1.3 times, excessive crimping is applied to the filament fed into the crimping machine, resulting in physical embrittlement, or the problem of not being able to impart uniform crimping to the left and right edges of the filament bundle due to the change in filament width.

[0049] In addition, in order to achieve the physical properties of cigarette filters, the number of curls of the tow ranges from 25 to 50 per inch (ea / inch).

[0050] Finally, Lyocell tow is characterized by a fineness range of 25,000 to 45,000 deniers (i.e., fineness) to achieve optimal cigarette filter performance.

[0051] At this point, when the thickness of the Lyocell filament bundle is less than 25,000 denier or greater than 45,000 denier, it is difficult to ensure the processability and physical properties of the cigarette filter. By adjusting the draw ratio of the crimping machine, the fineness of this Lyocell filament bundle can be achieved in the spinning process by adjusting the fineness of the Lyocell multifilament monofilaments to the range of 2.0 to 2.8 denier.

[0052] Furthermore, cigarette filters according to one embodiment of the invention can generally be divided into ordinary type and ultra-thin type, and the present invention can be applied to ordinary type cigarette filters.

[0053] Cigarette filters manufactured using the aforementioned filaments can achieve the required inhalation resistance for various cigarettes and can uniformly achieve the required physical properties of cigarette filters (filter circumference, inhalation resistance).

[0054] The method for manufacturing the lyocell material for cigarette filters of the present invention will be described in more detail below, according to each step.

[0055] [Step (S1)]

[0056] In this invention, step (S1) is a step of spinning a lyocell spinning solution comprising a cellulose slurry and an aqueous solution of N-methylmorpholine-N-oxide (NMMO). At this time, the lyocell spinning solution may contain 8–13 wt% cellulose slurry and 87–92 wt% an aqueous solution of N-methylmorpholine-N-oxide, and the cellulose slurry may contain 85–97 wt% α-cellulose and may have a degree of polymerization (DPw) of 600–1700.

[0057] If the content of the cellulose slurry is less than 8% by weight, it is difficult to achieve the fiber properties; if its content exceeds 13% by weight, it may be difficult to dissolve in aqueous solution. Furthermore, if the content of the N-methylmorpholine-N-oxide aqueous solution is less than 87% by weight, the dissolution viscosity increases significantly, which is not preferred; if its content is greater than 92% by weight, the spinning viscosity decreases significantly, making it difficult to produce uniform fibers in the spinning step.

[0058] In the aqueous solution of N-methylmorpholine-N-oxide, the weight ratio of N-methylmorpholine-N-oxide to water can be from 93:7 to 85:15. If the weight ratio of N-methylmorpholine-N-oxide to water is greater than 93:7, the dissolution temperature increases, which may cause cellulose to decompose during dissolution. If the weight ratio is less than 85:15, the solvent's solubility decreases, making it difficult to dissolve cellulose.

[0059] Using the above-described spinning solution, it is discharged from the spinning nozzle of a planar or annular spinneret. At this time, the spinneret is used to discharge the filamentous spinning solution through an air gap into the coagulation liquid in the coagulation bath. The step of discharging the spinning solution from the spinneret can be performed at 100–120°C.

[0060] Furthermore, in step (S1), spinning is performed simultaneously with adjusting the discharge rate and spinning speed to ensure that the fineness of each filament of the lyocell multifilament is 2.0 to 2.8 denier. Specifically, when spinning the lyocell filaments, adjusting the draw ratio of the crimping machine (described later) to achieve a fineness of each filament within this range prevents deterioration of the processability of cigarette filters and more effectively achieves the physical properties required by the industry.

[0061] [Step (S2)]

[0062] In this invention, step (S2) is the step of solidifying the lyocell spinning solution after spinning in step (S1) to obtain lyocell multifilament, and the solidification in step (S2) may include: a primary solidification step by air quenching (Q / A), which supplies cooling air to the spinning solution to solidify it; and a secondary solidification step, in which the primary solidified spinning solution is immersed in a solidification solution to solidify it.

[0063] In step (S1), after the spinning solution is discharged through a planar or annular spinneret, it can be passed through an air gap between the spinneret and the coagulation bath. In this air gap, in the case of a planar spinneret, cooling air is supplied from one direction to the other; in the case of an annular spinneret, cooling air is supplied from the inside to the outside through an air cooling section located inside the spinneret, and a suction function can also be added on the other side or the outside. Primary coagulation can be achieved by supplying this cooling air to the air quenching of the spinning solution.

[0064] The Lyocell multifilament used in step (S2) of the solidification process has a single filament fineness of 2.0 to 2.8 denier.

[0065] At this point, the factors affecting the physical properties of the Lyocell multifilament obtained in step (S2) are the temperature and flow rate of the cooling air in the air gap section, and the solidification in step (S2) can be performed by supplying cooling air at a temperature of 4 to 15°C and a flow rate of 50 to 250 L / m3 to the spinning solution.

[0066] If the temperature of the cooling air during primary solidification is below 4°C, the surface temperature of the spinneret may become lower, resulting in an uneven cross-section of the Lyocell multifilament and poor spinning processability. If the temperature is above 15°C, the primary solidification using cooling air will be insufficient, further worsening the spinning processability.

[0067] In addition, if the airflow of the cooling air during primary solidification is less than 50 L / m3, the primary solidification using cooling air will be insufficient, resulting in poor spinning processability and filament breakage. If the airflow is greater than 250 L / m3, the air may cause the spinning solution discharged from the spinneret to slosh, which will also worsen the spinning processability.

[0068] After primary solidification using air quenching, the spinning solution can be supplied to a coagulation bath containing a coagulation solution for secondary solidification. On the other hand, for proper secondary solidification, the temperature of the coagulation solution can be equal to or lower than 30°C. This is to ensure that the secondary solidification temperature does not exceed the required temperature, so as to maintain the solidification rate appropriately. Here, the coagulation solution can be prepared and used with components common in the art to which this invention pertains, and therefore there are no particular limitations.

[0069] [Step (S3)]

[0070] In this invention, step (S3) is a step of washing the Lyocell multifilament obtained in step (S2). More specifically, this is a step of introducing the Lyocell multifilament obtained in step (S2) into the traction roller and then introducing it into a washing bath for washing.

[0071] In the washing step of the filament, considering the recovery and reuse of solvent after washing, a washing solution with a temperature of 0 to 100°C can be used, and water can be used as the washing solution. Other additives may also be included as needed.

[0072] [Step (S4)]

[0073] In this invention, step (S4) is a step of treating the Lyocell multifilament washed in step (S3) with an oiling agent.

[0074] For the oil treatment, the method can be to immerse the filament bundle in a bath composed of an oil-based makeup and then drain it.

[0075] The oiling treatment can be performed while the multifilament is completely immersed in the oil, and the amount of oil adhering to the filament can be kept constant by pressure rollers attached to the inlet roller and release roller of the oiling treatment device.

[0076] Furthermore, unlike oils used for ordinary fibers, the oils used to coat the filaments can be specifically developed for lyocell.

[0077] According to a preferred embodiment, the oil optimizes the manufacturability of the cigarette filter tip by imparting a uniform lubricating function and an appropriate level of smoothness and cohesion to the cigarette filter tow. Furthermore, to minimize the deformation of the filter tip due to the smoker's saliva and the resulting decrease in filter hardness during smoking, the oil can slow down the rate at which the filter tip hardens by imparting hydrophobicity that delays saliva penetration into the filter tip. In addition, it can consist of components that are harmless to the smoker's body even if a certain amount of oil remains in the cigarette filter tip.

[0078] However, the oil reduces friction that occurs when the filament comes into contact with the drying roller, guide, and during the crimping process, and also helps to better form crimps between the fibers. Therefore, there are no particular restrictions on its type, as long as it is commonly used in the manufacture of Lyocell filaments.

[0079] In a preferred example, the oil may contain one or more of the following: selected from the group consisting of lubricating components, cohesion components, smoothness components, and hydrophobic components.

[0080] The oil can be used at a concentration of 2-8% by weight or 3-7% by weight for the lyocell multifilament. Maintaining the oil content within this range can reduce friction generated when the lyocell multifilament comes into contact with the device during the crimping step, and also helps to better form crimps between the fibers.

[0081] [Step (S5)]

[0082] Step (S5) is to crimp the lyocell multifilament that has been treated with oil in step (S4) to obtain a crimped filament bundle.

[0083] Specifically, the method involves applying steam and pressure to oil-treated Lyocell multifilaments to perform crimping, and crimped tows can be obtained through step (S5).

[0084] As used in this specification, the term "crimp" primarily refers to imparting a crimp to a filament to give the fiber a bulky feel. In this invention, the crimping process can be performed using a stuffer box equipped with pressure rollers. These pressure rollers can be clamping rollers.

[0085] The lyocell tow used in cigarette filters proposed in this invention has a range of draw ratios in the coiling machine during the tow manufacturing process to achieve optimal filter properties.

[0086] According to a preferred embodiment, in the curling process, the Lyocell cigarette filter tow can be applied to the filaments with a process draft condition of 1.01 to 1.3 times calculated according to Equation 1 to impart uniform curling.

[0087] Furthermore, the conditions of the machine that imparts uniform crimping based on the crimping draft conditions can be changed, and the factors that can vary include adjusting the pressure of the steam box supplied to the front end of the crimping device, the pressure applied to the rollers of the crimping device, and the pressure conditions of the scraper.

[0088] For example, the front end of the packing box is equipped with a steambox for steam treatment of the filament bundles, and the steambox can be controlled to meet the condition that the steam pressure supplied to the steambox is 0.1 to 3.0 kgf / cm². 2 The pressure applied to the press roller of the winding device is 1.5–4 kgf / cm². 2 The pressure of the scraper is 0.1–3 kgf / cm². 2 A uniform curl can be achieved by controlling the conditions described above.

[0089] If the steam pressure is less than 0.1 kgf / cm 2 If the modulus of the filament is not reduced to a level suitable for the process, it cannot form a crimp efficiently, especially if the pressure is greater than 3.0 kgf / cm. 2 If too much steam is supplied, the modulus of the filament is minimized, but due to the excessive water content, the required number of crimps cannot be uniformly imparted.

[0090] Furthermore, if the pressure applied through the pressure roller is less than 1.5 kgf / cm 2 Because it is impossible to impart a uniform thickness to the input filaments, the required number of crimps cannot be formed uniformly. If the pressure is greater than 4 kgf / cm², 2 If the applied pressure is too high, the moisture or oil content in the tow will decrease rapidly, preventing the filaments from passing smoothly through the packing box. In this case, it is preferable to maintain the gap between the pressure rollers at 0.01–3.0 mm. If the gap between the pressure rollers is less than 0.01 mm, the pressure on the filaments will be too high, preventing the formation of curls, or causing damage to the filament surface due to friction after formation. If the gap is greater than 3.0 mm, filament slippage will occur between the pressure rollers, making it difficult to form uniform curls.

[0091] Furthermore, the scraper is used for up-and-down movement to impart uniform curling after passing through the pressure roller. If the pressure of this scraper is less than 0.1 kgf / cm², 2If the pressure inside the packing box is insufficient to fix the upper plate, the filament bundle will remain inside the packing box for an extended period, disrupting the continuity of the process. Alternatively, if an appropriate dwell time is not provided, the required number of filament curls cannot be adjusted. If the pressure exceeds 3.0 kgf / cm², this can also cause problems. 2 Because the filaments cannot be smoothly discharged from the packing box, the curled shape becomes irregular.

[0092] The crimped tow under the conditions described above can have and maintain a crimp of 25–50 curls / inch or 30–45 curls / inch. Furthermore, when formed into single and composite filters with filter rods of 24.2 mm and 24.5 mm diameter respectively, it exhibits an inhalation resistance of approximately 240–590 PD (mmH2O) according to the measurement standard KS H ISO 6565. Different inhalation resistance values ​​are applied to the filters depending on the cigarette product. Therefore, the lyocell crimped tow of the present invention can be biodegraded and removed in a short time, thus being not only environmentally friendly, but also, when manufactured into cigarette filters, can more effectively meet the required inhalation resistance, filter stiffness, filter removal efficiency, and other physical properties than in the past, thereby maximizing its effectiveness.

[0093] [Step (S6)]

[0094] Step (S6) is to dry the crimped filament bundle obtained in step (S5) at a constant temperature.

[0095] Specifically, the oil extraction (Pick Up) of the filament bundles uniformly immersed in the oil treatment bath can impart a uniform level of curling during the crimping process.

[0096] Subsequently, when the crimped tow is dried using a continuous drying device, a final Lyocell crimped tow containing a uniform amount of oil can be produced.

[0097] The step of drying the crimped filament bundle can be performed at 105–135°C for 15–45 minutes, or at 110–130°C for 20–40 minutes, using a continuous drying device.

[0098] If the drying temperature is equal to or lower than 105°C, the filaments will not dry completely, making it impossible to adjust the moisture content to the required level. If the temperature is equal to or higher than 135°C, the whiteness will decrease due to yellowing. Furthermore, if the drying time is less than 15 minutes, irregular undried portions will be produced. If the time is more than 45 minutes, the surface of the filaments will be damaged due to excessive drying time, and the whiteness will decrease due to yellowing.

[0099] Furthermore, the final tow (lyocell tow for cigarette filters) produced after drying can have a thickness range of 25,000 to 45,000 deniers.

[0100] At this point, when the thickness of the Lyocell filament bundle is less than 25,000 denier or greater than 45,000 denier, it is difficult to ensure the processability and physical properties of the cigarette filter.

[0101] Furthermore, in the spinning process of step (S1), the fineness of the lyocell multifilament is adjusted to the range of 2.0 to 2.8 denier, and the draw ratio of the crimping machine in step (S5) is adjusted, thereby obtaining the range of thickness of the lyocell filament bundle.

[0102] Cigarette filters made of Lyocell material

[0103] According to another embodiment of the invention, a lyocell material for cigarette filters can be provided, comprising a crimped tow formed from lyocell multifilaments obtained by spinning a lyocell spinning solution containing cellulose slurry and an aqueous solution of N-methylmorpholine-N-oxide (NMMO), wherein the crimped tow is a lyocell tow having a thickness range of 25,000 to 45,000 deniers.

[0104] The number of curls in the lyocell bundle can be 25 to 50 per inch.

[0105] The lyocell spinning solution may contain 8-13% by weight of cellulose slurry and 87-92% by weight of an aqueous solution of N-methylmorpholine N-oxide.

[0106] The cellulose slurry may contain 85 to 99% by weight of α-cellulose and may have a degree of polymerization (DPw) of 600 to 1700.

[0107] Furthermore, according to another example of the invention, a cigarette filter can be provided comprising the aforementioned cigarette filter material as a lyocell filament bundle.

[0108] The composition of the cigarette filter is not limited except for the lyocell filament bundle.

[0109] For example, the cigarette filter tip may include cylindrical lyocell tows, plasticizers, curing agents, etc., wherein the lyocell tows contain multiple lyocell fibers.

[0110] The multiple lyocell fibers can be connected to each other by a curing agent to exhibit a structure in which the fiber surface and the curing agent are in contact.

[0111] The curing agent can be a known material used to increase the hardness of the filter tip. For example, the curing agent may include cellulose derivatives, vinyl derivatives, vinyl emulsion resins, natural polymers including sodium alginate, starch and starch derivatives, etc.

[0112] Therefore, this invention provides a lyocell cigarette filter tow that achieves filter performance (manufacturability, filter properties) comparable to cellulose acetate, currently used cigarette filter material. Furthermore, this specification allows for the manufacture of existing cellulose acetate cigarette butts (filters) using a more environmentally friendly process than in the past.

[0113] Furthermore, when using lyocell tow manufactured by the method described above, ordinary cigarette filters can be manufactured uniformly, and the required physical properties (filter circumference, inhalation resistance) can be achieved uniformly.

[0114] Beneficial effects

[0115] According to the present invention, by setting an optimal fineness range for the lyocell tow, optimal processability for manufacturing cigarette filters can be ensured, wherein the lyocell tow is given a crimp that achieves filter properties comparable to those of cellulose acetate used as cigarette filters in the present invention.

[0116] Furthermore, cigarette filters manufactured using the aforementioned lyocell filaments can achieve the inhalation resistance required by various cigarettes and can exhibit their physical properties (filter circumference, inhalation resistance).

[0117] Furthermore, the present invention can provide lyocell tow in an environmentally friendly manner, thus reducing environmental pollution caused by discarded cigarette butts by replacing traditional cellulose acetate cigarette filters.

[0118] In other words, the present invention has excellent biodegradability, processability, and physical properties, and therefore can demonstrate economic benefits by replacing traditional ordinary cigarette filter materials. Detailed Implementation

[0119] The invention will be described in more detail below through embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0120] Example 1

[0121] A cellulose slurry with a degree of polymerization (DPw) of 820 and an α-cellulose content of 93.9% was mixed with a NMMO / H2O mixed solvent (weight ratio 90 / 10) containing 0.01% by weight of propyl gallate to prepare a spinning solution with a concentration of 12% by weight for manufacturing cigarette filter tows. First, the spinning solution was maintained at a spinning temperature of 110°C at the spinning nozzle, and spinning was performed while adjusting the discharge rate and spinning speed to achieve a fineness of 2.4 denier for each filament.

[0122] The filamentous spinning solution discharged from the spinning nozzle is supplied to the coagulation solution in the coagulation bath through an air gap section. At this time, the operating temperature in the air gap section is 8°C and the airflow rate is 100 L / m³. 3 Cooling air is used to perform primary coagulation of the spinning solution. The coagulated solution is at a temperature of 25°C and consists of 75% by weight water and 25% by weight N-methylmorpholine-N-oxide (NMMO). The concentration of the coagulated solution is continuously monitored using sensors and a refractometer.

[0123] The solidified filaments passing through the traction rollers are washed with a washing liquid sprayed by a washing device to remove residual N-methylmorpholine-N-oxide in the filaments.

[0124] Then, the washed filaments are immersed in a treatment bath containing 2% by weight of oil.

[0125] Using a nip roller installed at the discharge section of the treatment bath at 2 kgf / cm 2 The pressure is applied to the filaments immersed in the treatment bath, and then they are fed into a crimping device (Crimper M / C) to give them crimping.

[0126] At this point, the crimping ratio is assigned, i.e., the crimping machine draw ratio is set to 1.1 times, at 0.3 kgf / cm. 2 Supply steam to the steam box and set the pressure on the crimper M / C roller to 2.5 kgf / cm². 2 And set the Doctor Blade pressure to 1.0 kgf / cm. 2 The prepared filaments are then passed through a continuous drying apparatus set at 120°C to obtain the dried filament product.

[0127] The obtained filaments were used to manufacture a cigarette filter with a target inhalation resistance of 450±12% mmH2O for ordinary filters.

[0128] Example 2

[0129] Except for adjusting the monofilament fineness to 2.6 denier and the crimper draft ratio to 1.05, the lyocell tow for cigarette filters was manufactured in the same manner as in Example 1.

[0130] Example 3

[0131] Except for adjusting the monofilament fineness to 2.8 denier and the draw ratio of the crimping machine to 1.2 times, the lyocell filament bundle for cigarette filters was manufactured in the same manner as in Example 1.

[0132] Comparative Example 1

[0133] Except for adjusting the draw ratio of the curling machine to 1.0, the lyocell filament bundle for cigarette filters was manufactured in the same manner as in Example 1.

[0134] Comparative Example 2

[0135] Except for adjusting the draw ratio of the curling machine to 1.35 times, the lyocell filament bundle for cigarette filters was manufactured in the same manner as in Example 1.

[0136] Comparative Example 3

[0137] Except for adjusting the draw ratio of the curling machine to 1.5 times, the lyocell filament bundle for cigarette filters was manufactured in the same manner as in Example 1.

[0138] Comparative Example 4

[0139] Except for adjusting the monofilament fineness to 3.0 denier and the draw ratio of the crimping machine to 1.1 times, the lyocell filament bundle for cigarette filters was manufactured in the same manner as in Example 1.

[0140] [Experimental Example]

[0141] For the Lyocell filament bundles of the embodiments and comparative examples, the physical properties of the filament bundles were measured by the following methods, and the results are shown in Table 1.

[0142] Physical property measurement methods

[0143] (1) Measure the fineness of the fiber bundle:

[0144] Take a 2m long sample of the filament bundle to be measured and place it in a constant temperature and humidity chamber at 20℃ and 65% for 24 hours. After fixing one end of the stabilized filament bundle, attach a 2kg weight to the other end. After stabilizing the filament bundle, which has elongated due to the load, for 5 seconds, cut it into 90cm pieces to obtain samples, and then measure the weight. Convert the filament fineness to the measured weight × 10000 using the denier conversion method.

[0145] (2) Measure the number of curls

[0146] Measurements were performed according to KS K 0326 specifications. Twenty undamaged curled samples were taken and adhered to pre-prepared glossy paper sheets (spaced 25 mm apart) using an adhesive containing 4%–5% celluloid. Each fiber sample was stretched by 25 ± 5% relative to its adhered length. The samples were then left to dry to allow the adhesive to dry. For each sample, an initial load equivalent to 1.96 / 1000 cN (=2 mgf) per 1 De was applied using a curl tester. The number of curls within 25 mm was counted and represented as the average value after removing the decimal point.

[0147] (3) Measure the shape of the curl.

[0148] The morphology of the curls was sampled in the same manner as the curl count was measured, and their uniformity was then visually confirmed using an optical microscope.

[0149] (4) Manufacturability of cigarette filters

[0150] Regarding the manufacturability of cigarette filters, the process maintainability of feeding the tow into the cigarette filter manufacturing equipment until the time point when a batch of samples is used up was confirmed.

[0151] (5) Measure the inhalation resistance and circumference of the cigarette filter.

[0152] Cigarette filter rods were manufactured using the tows produced in the embodiments and comparative examples, and the inhalation resistance of each rod was measured using an inhalation resistance and circumference tester in accordance with KSH ISO 6565 specifications.

[0153] [Table 1]

[0154]

[0155] As shown in Table 1, in Examples 1 to 3, the number of curls was uniformly formed according to the manufacturing conditions of the tow, and the manufactured tow could achieve the physical properties required for a cigarette filter by setting the equipment conditions when manufacturing the cigarette filter. However, in Comparative Example 1, the tow could not be manufactured even when the manufacturing conditions were set to the appropriate conditions, and therefore the performance of the filter could not be confirmed.

[0156] Furthermore, in the cases of Comparative Examples 2 to 4, filament bundles can be manufactured, but due to unreasonable manufacturing conditions, it is difficult to manufacture uniform filament bundles.

[0157] That is, Comparative Examples 1 to 3 are not within the draw ratio range of the coiling machine of the present invention, and it is impossible to produce filament bundles, or even if filament bundles are produced, the coiling shape is poor, and cigarette filters cannot be continuously produced. Therefore, compared with the examples, their inhalation resistance is also lower. In addition, in the case of Comparative Example 4, when spinning is performed using spinning solution, the fineness of each filament is 3.0 denier, which exceeds the fineness range of each filament of the present invention, and it was confirmed that since the fineness range of the filament bundle exceeds 4000 denier (De), the processability and physical properties of the cigarette filter are poor compared with Examples 1 to 3.

[0158] Therefore, the comparative examples confirmed that when manufacturing cigarette filters using the manufactured tow, the processability could not be maintained due to the inhomogeneity of the tow, and the performance of the filter was difficult to achieve due to the inhomogeneity of the tow.

[0159] On the other hand, in the cases of Examples 1 to 3, when manufacturing lyocell cigarette filter tow, its fineness range of 25,000 to 45,000 denier can be achieved by adjusting the draw ratio of the coiling machine during the coiling process, thus enabling optimal cigarette filter performance. Therefore, according to the present invention, by providing lyocell tow with coiled properties comparable to those of currently used cellulose acetate cigarette filters, optimal processability for manufacturing cigarette filters can be ensured.

Claims

1. A method for manufacturing a lyocell material for cigarette filters, comprising the following steps: (S1) Spinning is performed on a Lyocell spinning solution containing cellulose slurry and an aqueous solution of N-methylmorpholine-N-oxide; (S2) The lyocell spinning solution after spinning is solidified to obtain lyocell multifilament; (S3) The obtained Lyocell multifilament is washed with water; (S4) Treat the washed Lyocell multifilament with an oiling agent; (S5) The lyocell multifilament treated with the oil agent is crimped to obtain crimped filament bundles; as well as (S6) The crimped filament bundle is dried. The step of obtaining crimped filament bundles includes: crimping the oil-treated lyocell multifilaments in a manner that satisfies a crimping machine draw ratio of 1.01 to 1.3 times, calculated by the following formula 1. The crimped filament bundle has a fineness range of 25,000 to 45,000 denier. Formula 1: Drafting machine draw ratio = V1 / V0 In Equation 1, V0 is the speed at which the oiled lyocell multifilament is fed into the crimping machine, and V1 is the surface linear velocity of the rollers of the crimping machine used to crimp the oiled lyocell multifilament. In this case, the units of V0 and V1 are the same.

2. The method for manufacturing lyocell material for cigarette filters according to claim 1, wherein, The single filament fineness of the Lyocell multifilament in step (S2) is 2.0 to 2.8 denier.

3. The method for manufacturing lyocell material for cigarette filters according to claim 1, wherein, The number of curls in the lyocell filament bundle is 25 to 50 per inch.

4. The method for manufacturing lyocell material for cigarette filters according to claim 1, wherein, The step (S5) is performed through the filling box of the curling device.

5. The method for manufacturing lyocell material for cigarette filters according to claim 4, wherein, The packing box is controlled to maintain a steam pressure of 0.1–3.0 kgf / cm². 2 The pressure applied to the pressure rollers of the crimping device is 1.5–4 kgf / cm. 2 The pressure of the scraper is 0.1–3.0 kgf / cm². 2 conditions.

6. The method for manufacturing lyocell material for cigarette filters according to claim 1, wherein, The step (S6) of drying the crimped filament bundle is performed using a continuous drying device at 105–135°C for 15–45 minutes.

7. The method for manufacturing lyocell material for cigarette filters according to claim 1, wherein, The lyocell spinning solution in step (S1) contains 8-13% by weight of cellulose slurry and 87-92% by weight of N-methylmorpholine-N-oxide aqueous solution.

8. The method for manufacturing lyocell material for cigarette filters according to claim 1, wherein, The cellulose slurry contains 85-99% by weight of α-cellulose and has a degree of polymerization of 600-1700.

9. A lyocell material for cigarette filters, manufactured according to the method for manufacturing a lyocell material for cigarette filters according to any one of claims 1 to 8, the lyocell material for cigarette filters comprising crimped filaments formed from lyocell multifilaments obtained by spinning a lyocell spinning solution containing cellulose slurry and an aqueous solution of N-methylmorpholine-N-oxide. The crimped filament bundle is a Lyocell filament bundle with a fineness range of 25,000 to 45,000 denier.

10. The lyocell material for cigarette filters according to claim 9, wherein, The number of curls in the crimped filament bundle is 25 to 50 per inch.

11. The lyocell material for cigarette filters according to claim 9, wherein, The lyocell spinning solution contains 8-13% by weight of cellulose slurry and 87-92% by weight of an aqueous solution of N-methylmorpholine-N-oxide.

12. The lyocell material for cigarette filters according to claim 9, wherein, The cellulose slurry contains 85-99% by weight of α-cellulose and has a degree of polymerization of 600-1700.

13. A cigarette filter comprising a lyocell material for cigarette filters according to any one of claims 9 to 12.

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