JP7758272B2 - Cigarette filter containing lyocell tow and method for producing same - Google Patents

Description

The present invention relates to a cigarette filter containing lyocell tow. Specifically, the present invention relates to a cigarette filter comprising lyocell tow made of a plurality of lyocell fibers, a binder that binds the lyocell fibers together, and a solvent dispersed in the internal space of the cigarette filter containing the lyocell tow, wherein the solvent contains a polyhydric alcohol.

This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0173493, filed December 7, 2021, and incorporates all of the contents disclosed in the documents of that Korean patent application as part of this specification.

Generally, to manufacture cigarettes, various types of leaf tobacco are first blended and processed to achieve the desired aroma and flavor. The processed leaf tobacco is then cut to produce tobacco shreds, which are then wrapped in cigarette paper to produce filterless cigarettes. Next, a filter is attached to the filterless cigarette, if desired.

Cigarette paper can be made from flax, wood pulp, etc., and is required to maintain combustion properties and the flavor of tobacco during combustion. The cigarette filter may contain activated carbon, flavoring substances, etc., and may consist of a mono-filter or multiple filters, wrapped in cigarette filter wrapping paper. The tobacco shreds and the cigarette filter are connected by tipping paper, which may contain fine holes.

General cigarette filters use cellulose acetate tow, which is made by extracting and acetylating cellulose from wood pulp. Recently, however, environmentally friendly alternative materials have been developed to protect the natural environment and reduce costs. For example, tow made from lyocell fiber, which is made by fiberizing cellulose itself, is being developed in place of cellulose acetate.

In cigarette filters, hardness is an important indicator related to consumer needs and the workability of cigarette manufacturing. Cigarette filters made from tow, a bundle of fiber strands, are not suitable due to their low hardness. Therefore, in order to be used in cigarette filters, the hardness must be increased to a certain level. For example, methods for increasing filter hardness include using a hardener or a plasticizer. The method using a hardener involves using a binder-like substance to bond the fiber strands together, imparting hardness to the filter and making it stronger. The method using a plasticizer involves using a specific substance to partially dissolve or plasticize the fibers themselves, forming junctions between the fibers, and then plasticizing the resulting mixture.

Conventional cellulose acetate uses plasticizers (triacetin, triethyl citrate) to partially dissolve the fiber strands, which then harden the fiber strands together, giving the cigarette filter hardness. However, since there are currently no plasticizers available for lyocell fiber, it is essential to develop a hardness enhancer that is suitable for lyocell fiber.

The inventors recognized the technical challenges inherent in the above-mentioned lyocell fiber material and, after sustained research into lyocell tow with excellent functionality suitable for use in cigarette filters, completed the present invention.

Korean Patent Publication No. 10-2015-0116612

We aim to provide a cigarette filter that contains lyocell tow, an environmentally friendly material, that can resolve material issues such as processability during processing in order to maintain the hardness that lyocell tow fundamentally possesses.

According to a first aspect of the present invention,
The present invention provides a cigarette filter comprising: a lyocell tow consisting of a plurality of lyocell fibers; a binder that binds the lyocell fibers together; and a solvent dispersed in the internal space of the cigarette filter containing the lyocell tow, wherein the solvent contains a polyhydric alcohol.

In one embodiment of the present invention, the polyhydric alcohol is a diol having a C1 to C4 alkylene group.

In one embodiment of the present invention, the polyhydric alcohol is contained in an amount of 0.5 to 25 parts by weight based on 100 parts by weight of lyocell tow.

In one embodiment of the present invention, the binder is hydroxypropyl methylcellulose, hydroxypropyl cellulose, polyvinyl alcohol, ethylene vinyl acetate, polyvinyl acetate, polyvinylpyrrolidone, polyester, or a combination thereof.

In one embodiment of the present invention, the binder is contained in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of lyocell tow.

In one embodiment of the present invention, the solvent further comprises a monohydric alcohol selected from methanol, ethanol, propanol, and combinations thereof.

According to a second aspect of the present invention,
The present invention provides a method for manufacturing the above-mentioned cigarette filter, the method including the steps of: manufacturing lyocell tow using a plurality of lyocell fibers; mixing a binder and a solvent to prepare a binder solution; spraying the binder solution onto the lyocell tow and storing the lyocell tow so that the lyocell fibers can be bound to each other by the binder; and wrapping the lyocell tow, in which the lyocell fibers are bound by the binder, in cigarette paper to manufacture a cigarette filter.

In one embodiment of the present invention, the polyhydric alcohol is contained in an amount of 5 to 50 parts by weight based on 100 parts by weight of the binder solution.

In one embodiment of the present invention, the solvent further contains a monohydric alcohol.

In one embodiment of the present invention, the monohydric alcohol is methanol, ethanol, propanol, or a combination thereof.

In one embodiment of the present invention, the monohydric alcohol is contained in an amount of 5 to 60 parts by weight based on 100 parts by weight of the binder solution.

In one embodiment of the present invention, the binder solution is sprayed onto the lyocell tow in an amount of 5 to 30 parts by weight based on 100 parts by weight of the lyocell tow.

A cigarette filter according to one embodiment of the present invention contains lyocell tow, an environmentally friendly material, while overcoming the material problems previously associated with lyocell tow and exhibiting excellent hardness.

Unlike other cigarette filters that use lyocell tow, the cigarette filter according to one embodiment of the present invention can achieve the excellent hardness described above without having to be dried at high temperatures for long periods of time, thereby improving processability and productivity in the manufacture of cigarette filters.

A cigarette filter according to one embodiment of the present invention contains a polyhydric alcohol, which not only acts as a binder to improve the hardness of the cigarette filter, but also serves as a release agent during roll processing in the cigarette filter manufacturing process, thereby reducing product defects and improving workability.

1 is a diagram showing a schematic configuration of a smoking article according to one embodiment of the present invention.

Specific examples will be described in detail below based on illustrative drawings. When assigning reference numerals to components in each drawing, please note that the same components will be assigned the same numerals whenever possible, even if they appear in different drawings. Furthermore, when describing specific examples, if it is determined that a detailed description of related publicly known configurations or functions would hinder understanding of the specific examples, that detailed description will be omitted.

In addition, when describing components of specific examples, terms such as first, second, A, B, (a), and (b) may be used. These terms are used to distinguish the component from other components, and do not limit the nature, order, or sequence of the components. When a component is described as being "coupled," "bonded," or "connected" to another component, it should be understood that the component may be directly coupled or connected to the other component, but that other components may also be "coupled," "coupled," or "connected" between each component.

Components included in one specific example and components having common functions will be described using the same names in other specific examples. Unless otherwise specified, the description of one specific example may also be applied to other examples, and detailed descriptions will be omitted to the extent that they overlap.

As used herein, the term "smoking article" may refer to an article capable of generating aerosol, such as tobacco (cigarette), cigar, etc. Smoking articles may include an aerosol-generating substance or an aerosol-forming substrate. Smoking articles may also include solid substances based on tobacco raw materials, such as flat tobacco, shredded tobacco, or reconstituted tobacco. Smoking substances may also include volatile compounds. Smoking articles may include several segments each with their own functionality, and such segments are represented by "... segments." As used herein, smoking articles may refer not only to combustible cigarettes, but also to heated cigarettes used with an aerosol-generating device (not shown), such as electronic cigarette devices.

As used herein, the terms "upstream" and "downstream" are used to indicate the relative positions of segments that make up a smoking article, with respect to the direction in which a user draws air using the smoking article. A smoking article includes an upstream end (i.e., the portion where air enters) and an opposing downstream end (i.e., the portion where air exits). When using a smoking article, a user can bite the downstream end of the smoking article. The downstream end is located downstream of the upstream end; the term "end" may also be described as "terminal end."

The present invention relates to a cigarette filter applicable to smoking articles. According to one embodiment of the present invention, the cigarette filter includes a lyocell tow composed of a plurality of lyocell fibers, a binder that binds the lyocell fibers together, and a solvent dispersed in the interior space of the cigarette filter containing the lyocell tow. The lyocell fiber is an environmentally friendly fiber made from cellulose extracted from wood pulp. The lyocell tow refers to a bundle formed by cross-linking adjacent lyocell fibers. According to one embodiment of the present invention, the lyocell fiber may have a fineness of 1.0 denier to 12.0 denier. According to another embodiment of the present invention, the lyocell fiber bundles constituting the lyocell tow may have a fineness of 15,000 denier to 45,000 denier. A binder suitable for the lyocell fiber is mixed with a solvent to prepare a binder solution, and the binder solution is sprayed onto the lyocell tow, thereby forming a structure with a certain level of hardness. Even after spraying and a long period of time, the binder and some of the solvent components do not flow out and may be contained in the final cigarette filter.

The binder contained in the cigarette filter binds the lyocell fibers together and imparts a certain level of hardness to the lyocell tow. The binder is a material suitable for application to lyocell fibers, and any common material known in the art can be used. According to one embodiment of the present invention, the binder may be hydroxypropyl methyl cellulose (HPMC), hydroxypropyl cellulose (HPC), polyvinyl alcohol (PVA), ethylene vinyl acetate (EVA), polyvinyl acetate (PVAc), polyvinyl pyrrolidone (PVP), polyester, or a combination thereof. Specifically, the binder may be hydroxypropyl methyl cellulose, polyester, or a combination thereof.

The polyester is a synthetic resin made by reacting a polyhydric organic acid with a polyhydric alcohol, and has suitable resistance to water and various compounds. According to one embodiment of the present invention, the polyester is a copolymer of an aromatic monomer and an aliphatic monomer. The aromatic monomer adds structural stability to the polyester, and the aliphatic monomer adds structural flexibility to the polyester. Polyesters containing the aromatic and aliphatic monomers can easily bond with other components, such as lyocell fibers, and thus can function as binders. The aromatic monomer may be a polyhydric organic acid or a polyhydric alcohol, and similarly, the aliphatic monomer may be a polyhydric organic acid or a polyhydric alcohol.

According to one embodiment of the present invention, the aromatic monomer is a dicarboxylic acid having a C5 to C12 arylene group or heteroarylene group. Exemplarily, the dicarboxylic acid having a C5 to C12 arylene group or heteroarylene group may be phthalic acid, terephthalic acid, or isophthalic acid. According to one embodiment of the present invention, the aliphatic monomer is a diol having a C1 to C6 alkylene group, a dicarboxylic acid having a C2 to C12 alkylene group, or a combination thereof. Exemplarily, the diol having a C1 to C6 alkylene group is ethylene glycol, and the dicarboxylic acid having a C2 to C12 alkylene group is sebacic acid. In the case of polyesters, because carboxylic acid groups and hydroxyl groups can be formed by a condensation reaction in a 1:1 ratio, the carboxylic acid group-containing monomer can be the aforementioned dicarboxylic acid having a C5 to C12 arylene or heteroarylene group, dicarboxylic acid having a C2 to C12 alkylene group, or a combination thereof, and the hydroxyl group-containing monomer can be a diol having a C1 to C6 alkylene group. The arylene group, heteroarylene group, or alkylene group can be substituted or unsubstituted. If substituted, the main chain of the arylene group, heteroarylene group, or alkylene group can be substituted with a substituent commonly known in the art, such as a C1 to C4 alkyl group, a C1 to C4 alkoxy group, or a halogen group.

The binder can be applied to the lyocell tow in the form of a binder solution together with a solvent. After application, the binder does not flow out even when the lyocell tow dries or is left for a long time, but remains between the lyocell fibers, thereby improving the hardness of the lyocell tow. According to one embodiment of the present invention, the binder is contained in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of lyocell tow. Specifically, the content of the binder is 0.1 to 5 parts by weight, 0.2 to 0.3 parts by weight, 0.4 to 5 parts by weight, 4 to 3.5 parts by weight, 3 to 2.5 parts by weight, or 0.1 to 5 parts by weight, 0.2 to 4 parts by weight, or 0.3 to 3 parts by weight. When applied within this range, the binder can increase the hardness to an appropriate level without reducing the basic filtering function of the lyocell tow.

The solvent contained in the cigarette filter is basically included in the binder solution to disperse the binder. After the binder solution is sprayed onto the lyocell tow, some of the solvent is removed by drying or leaving it for a long period of time. The remaining solvent remains as a component inside the cigarette filter containing the lyocell tow, imparting additional functionality to the cigarette filter. The solvent remaining in the cigarette filter contains a polyhydric alcohol. Here, polyhydric alcohol refers to a compound containing two or more hydroxy groups. The polyhydric alcohol acts as a release agent when the lyocell tow is processed with a mechanical roll or the like to apply it to the cigarette filter. Specifically, when lyocell tow is processed with a mechanical roll or the like without a release agent, the lyocell tow can become caught in the mechanical roll or the like due to the adhesive strength of the binder, etc. However, lyocell tow containing a polyhydric alcohol reduces this phenomenon and improves processability. Furthermore, when the polyhydric alcohol is applied to lyocell tow, it is located between the lyocell fibers together with the binder, helping to improve the hardness of the lyocell tow in a short period of time, without the need for long-term drying at high temperatures. As a result, when using a solvent containing a polyhydric alcohol, the drying time can be significantly shortened, improving the processability of cigarette filter manufacturing.

According to one embodiment of the present invention, the polyhydric alcohol is a diol having a C1-C4 alkylene group. The diol refers to a compound having two hydroxy groups and is also called a glycol. The two hydroxy groups may be connected by a C1-C4 alkylene group, where the number of carbon atoms in the alkylene group refers to the number of carbon atoms directly connected between the two hydroxy groups. The alkylene group may be substituted or unsubstituted. If substituted, the main chain of the alkylene group may be substituted with a substituent commonly known in the art, such as a C1-C3 alkyl group, a C1-C3 alkoxy group, or a halogen group. According to one embodiment of the present invention, the polyhydric alcohol may be propylene glycol. Propylene glycol may be a more preferred compound for having the above-mentioned functionality as a polyhydric alcohol with an appropriate chain length.

The polyhydric alcohol can be applied to lyocell tow in the form of a binder solution together with a binder and other solvents. It remains unchanged in the lyocell tow or the cigarette filter to which it is applied before and after drying, imparting the aforementioned functionality, such as improved hardness and processability. According to one embodiment of the present invention, the polyhydric alcohol is contained in an amount of 0.5 to 25 parts by weight based on 100 parts by weight of lyocell tow. Specifically, the content of the polyhydric alcohol is 0.5 parts by weight or more, 0.6 parts by weight or more, 0.7 parts by weight or more, 0.8 parts by weight or more, 0.9 parts by weight or more, or 1 part by weight or more, and may be 25 parts by weight or less, 20 parts by weight or less, 15 parts by weight or less, 10 parts by weight or less, or 5 parts by weight or less, or may be 0.5 to 10 parts by weight, 0.7 to 7 parts by weight, or 1 to 5 parts by weight. When applied within the above range, the polyhydric alcohol can impart additional functionality to the cigarette filter without reducing the basic filter function of the lyocell tow.

According to one embodiment of the present invention, the solvent includes a monohydric alcohol, such as methanol, ethanol, propanol, or a combination thereof. Specific methods for adding the monohydric alcohol are described in the manufacturing method section. The monohydric alcohol is a more volatile component than water, and a large amount may disappear after drying. However, if the filter is stored at room temperature without undergoing a drying process, a certain level or more of the monohydric alcohol may remain in the final cigarette filter. The monohydric alcohol can replace water as a solvent in the binder solution, and not only helps to improve the hardness of the cigarette filter, but also exhibits additional functionality when applied to lyocell tow due to its bactericidal properties. According to one embodiment of the present invention, the monohydric alcohol is included in an amount of 1 to 500 parts by weight based on 10,000 parts by weight of lyocell tow. Because monohydric alcohols are more volatile than polyhydric alcohols or water, the content of the monohydric alcohol varies greatly. However, in one embodiment of the present invention, when the drying process is reduced and the product is stored at room temperature, a certain level of monohydric alcohol can be detected compared to when no monohydric alcohol is added. Therefore, the lower limit of the content range is considered more significant than the upper limit.

A cigarette filter containing lyocell tow according to one embodiment of the present invention has excellent hardness due to the binding of the binder. According to one embodiment of the present invention, the cigarette filter has a hardness of 85% or more. Specifically, the hardness of the cigarette filter may be 85% or more, 86% or more, 87% or more, 88% or more, or 89% or more. The hardness of the cigarette filter is a numerical value that represents the degree to which the diameter of the cigarette filter is maintained when the cigarette filter is pressed with a certain level of force in the vertical direction, and can be calculated specifically using the following calculation formula 1.

[Formula 1]
Filter hardness (%) = [Da]/D x 100

Here, D is the filter diameter (mm), and a is the distance (mm) the filter is pressed down by a 300 g weight. Measurement values required for calculating the hardness of the cigarette filter can be obtained using a device commonly used in the art, such as a Filtrona DHT 200 ^™ . The force applied when measuring hardness is based on the force applied when a smoker actually grips a cigarette. The hardness value of 85% or more obtained by the cigarette filter according to one embodiment of the present invention is technically significant in that it ensures a hardness level sufficient to replace conventional cigarette filters made of cellulose acetate using lyocell tow, an environmentally friendly material. Furthermore, the cigarette filter according to one embodiment of the present invention can achieve an excellent hardness value of 85% or more, as described above, even after the binder has been fixed at room temperature without undergoing a drying process at high temperatures, thereby significantly improving processability in product manufacturing.

The above-mentioned cigarette filter can be manufactured by the following manufacturing method. The manufacturing method includes the steps of: preparing lyocell tow using lyocell fibers; mixing a binder and a solvent to prepare a binder solution; spraying the binder solution onto the lyocell tow and storing it so that the lyocell fibers can be bound to each other by the binder; and wrapping the lyocell tow, with the lyocell fibers bound to each other by the binder, in cigarette paper to manufacture a cigarette filter. Because the manufacturing method basically relates to a method for manufacturing the above-mentioned cigarette filter, a description of the specific aspects embodied in the above content will be omitted, and the following will describe the characteristics of the manufacturing method in more detail.

First, lyocell tow is produced using multiple lyocell fibers. The produced lyocell tow has a bundle shape formed by adjacent lyocell fibers being cross-linked. In this process, a step of expanding the tow through blooming is further carried out. Expanding the tow through this blooming step allows the binder solution sprayed later to easily penetrate between the lyocell fibers that make up the lyocell tow.

Next, a binder and a solvent are mixed to prepare a binder solution. The binder solution is a substance sprayed onto the lyocell tow to improve its functionality, such as its hardness. Since some components of the binder solution may be lost during drying or storage after spraying, the composition of the binder solution may differ from the composition of the components that make up the cigarette filter. The binder can be embodied as described above, and since the components are not significantly lost even after drying or storage, the amount supplied to the lyocell tow through spraying remains almost unchanged in the final cigarette filter. According to one embodiment of the present invention, the binder is included in an amount of 5 to 40 parts by weight based on 100 parts by weight of the binder solution. Specifically, the content of the binder is 5 parts by weight or more, 6 parts by weight or more, 7 parts by weight or more, 8 parts by weight or more, 9 parts by weight or more, 10 parts by weight or more, and 40 parts by weight or less, 35 parts by weight or less, 30 parts by weight or less, 25 parts by weight or less, 20 parts by weight or less, or may be 5 to 40 parts by weight, 7 to 30 parts by weight, or 10 to 20 parts by weight. When the binder is formed into a binder solution within the above range, it can be easily sprayed and applied to the lyocell tow.

The solvent contains water in addition to a polyhydric alcohol. If the solvent is entirely composed of a polyhydric alcohol, the viscosity may be excessively high, making it difficult to disperse the binder. The remaining water may be present in an amount equal to the proportion of the solvent, such as the polyhydric alcohol, and some of the water will disappear during the drying process. According to one embodiment of the present invention, the polyhydric alcohol is present in an amount of 5 to 50 parts by weight based on 100 parts by weight of the binder solution. Specifically, the content of the polyhydric alcohol is 5 parts by weight or more, 6 parts by weight or more, 7 parts by weight or more, 8 parts by weight or more, 9 parts by weight or more, or 10 parts by weight or more, and may be 50 parts by weight or less, 45 parts by weight or less, 40 parts by weight or less, 35 parts by weight or less, or 30 parts by weight or less, or may be 5 to 50 parts by weight, 7 to 40 parts by weight, or 10 to 30 parts by weight. When used within the above range, the polyhydric alcohol can impart additional functionality to the cigarette filter without reducing the basic filter function of the lyocell tow.

The solvent may further include a monohydric alcohol. The monohydric alcohol is a component with a higher volatility than water and may disappear in large amounts after drying. However, if the filter is stored at room temperature without undergoing a drying process, a certain level or more of the monohydric alcohol may still be detected in the final cigarette filter. The monohydric alcohol is a component that can replace water in the solvent of the binder solution and can adjust the water content of the final cigarette filter. According to one embodiment of the present invention, the monohydric alcohol is methanol, ethanol, propanol, or a combination thereof. Specifically, the monohydric alcohol may be ethanol.

The monohydric alcohol may be included at a certain level or more to replace water. According to one embodiment of the present invention, the monohydric alcohol is included in an amount of 5 to 60 parts by weight based on 100 parts by weight of the binder solution. Specifically, the content of the monohydric alcohol is 5 parts by weight or more, 6 parts by weight or more, 7 parts by weight or more, 8 parts by weight or more, 9 parts by weight or more, or 10 parts by weight or more, and is 60 parts by weight or less, 55 parts by weight or less, 50 parts by weight or less, 45 parts by weight or less, 40 parts by weight or less, 35 parts by weight or less, or 30 parts by weight or less, and may be 5 to 60 parts by weight, 7 to 45 parts by weight, or 10 to 30 parts by weight. When used within the above range, the monohydric alcohol can effectively reduce the water content in the cigarette filter by a significant amount.

The binder solution prepared as described above is sprayed onto the lyocell tow. The binder solution may be sprayed onto the lyocell tow to an extent that overcomes the inherent hardness and other problems inherent to the lyocell tow without impairing the lyocell tow's basic filtering function. According to one embodiment of the present invention, 5 to 30 parts by weight of the binder solution is sprayed onto the lyocell tow, based on 100 parts by weight of the lyocell tow. Specifically, the amount of the binder solution sprayed is 5 parts by weight or more, 6 parts by weight or more, 7 parts by weight or more, 8 parts by weight or more, 9 parts by weight or more, or 10 parts by weight or more, and may be 30 parts by weight or less, 28 parts by weight or less, 26 parts by weight or less, 24 parts by weight or less, 22 parts by weight or less, or 20 parts by weight or less, or may be 5 to 30 parts by weight, 7 to 24 parts by weight, or 10 to 20 parts by weight. When the binder solution is sprayed within the above range, it can improve the functionality of the lyocell tow, such as its hardness. The method for spraying the binder solution is not particularly limited and may be a method commonly used in the art. For example, the binder solution may be sprayed using a nozzle spray, a brush spray, or an electric spray.

After spraying the binder solution onto the lyocell tow, it is stored to allow the binder to set and bind the lyocell fibers together. This process is different from long-term drying at high temperatures, and the binder solution can be stored at room temperature for, for example, six hours, and still be sufficient for the next process, improving processability in product manufacturing.

Tobacco filters are manufactured by wrapping lyocell tow, in which lyocell fibers are bound with a binder, in wrapping paper. If necessary, the lyocell tow can be processed to a standard suitable for application to cigarette filters using a mechanical roll or cutter.

The above-described cigarette filter can be applied to a smoking article. Figure 1 shows a schematic configuration of a smoking article according to one embodiment of the present invention. The smoking article 100 includes a smoking material portion 10 and a filter portion 20, and the above-described cigarette filter is applied to the filter portion 20 of the smoking article 100. In the smoking article 100, the smoking material portion 10 is located upstream of the filter portion 20.

The smoking material portion 10 can be filled with smoking material such as raw tobacco, flakes, or a mixture of leaf tobacco and flakes. Processed smoking material can be filled into the smoking material portion 10 in sheet or shredded form. The smoking material portion 10 can have an elongated rod shape, and its length, circumference, and diameter can be adjusted to sizes commonly used in the art, taking into account the amount of smoking material to be filled, user preferences, etc., without particular limitation. The smoking material portion 10 can contain at least one aerosol-generating substance selected from the group consisting of glycerin, propylene glycol, ethylene glycol, dipropylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and oleyl alcohol. The smoking material portion 10 can contain other additives, such as flavorants, humectants, and/or acetate compounds. The aerosol-generating substance and additives can be contained in the smoking material.

The filter unit 20 is disposed downstream of the smoking material unit 10 and serves as a filter through which the aerosol generated in the smoking material unit 10 passes just before the user inhales it. The filter unit 20 can be manufactured using various materials and shapes. The filter unit 20 according to one embodiment of the present invention basically comprises the above-described cigarette filter comprising lyocell tow, in which a plurality of lyocell fibers are bound together by a binder. The cigarette filter comprising the lyocell tow can replace all or part of the filter unit 20 of a conventional smoking article, and when replacing only part of it, conventional filter materials can be used together. Conventional filter materials include, for example, cellulose acetate filters and hollow tube filters.

While FIG. 1 shows that the filter unit 20 is a mono-filter consisting of a single filter, this is not limiting. For example, the filter unit 20 may be a dual filter or triple filter equipped with two acetate filters to increase filtering efficiency. Furthermore, although not shown, the filter unit 20 may contain a crushable capsule (not shown) inside, which is structured so that a coating encases an oral liquid containing a flavoring.

The exterior of the smoking material portion 10 and filter portion 20 can be wrapped in a wrapper 30a or 30b.

The smoking material portion 10 can be wrapped in a smoking material wrapper 30a. A portion of the tobacco smoke generated during the combustion of a typical smoking material portion 10 is released into the atmosphere through the smoking material wrapper 30a before passing through the cigarette filter, resulting in sidestream smoke that is unpleasant for secondhand smokers. Various attempts have been made to reduce sidestream smoke, such as incorporating fillers such as magnesium oxide, titanium oxide, cerium oxide, aluminum oxide, calcium carbonate, and zirconium carbonate into cigarette paper. However, simply applying such fillers to reduce sidestream smoke can result in a poor smoking experience, poor burn-off, and poor ash caking, making it difficult to solve these problems through an appropriate combination of materials. The smoking material wrapper 30a according to one embodiment of the present invention uses a filler containing a mixture of magnesium oxide (MgO and/or Mg(OH) ₂ ) and calcium carbonate (CaCO ₃ ) to reduce sidestream smoke while simultaneously preventing poor smoking experience, poor ash caking, and poor burn-off.

The filter unit 20 may be wrapped in a filter unit wrapper 30b. The filter unit wrapper 30b may be made of oil-resistant wrapping paper, and the inner surface of the filter unit wrapper 30b may further include aluminum foil.

The smoking material section 10 wrapped in the smoking material section wrapper 30a and the filter section 20 wrapped in the filter section wrapper 30b can be bonded and wrapped with tipping paper 40. As shown in FIG. 1, the tipping paper 40 may wrap at least a portion (e.g., a downstream portion) of the smoking material section wrapper 30a and the outer shell of the filter section wrapper 30b. In other words, at least a portion of the smoking material section 10 and the filter section 20 may be further wrapped and physically bonded with the tipping paper 40. According to one embodiment of the present invention, the tipping paper 40 may be made of non-porous wrapping paper that has not been treated for oil resistance, but is not limited to this. The tipping paper 40 may also contain a non-flammable material to prevent the filter section 20 from burning, but is not limited to this.

The configuration and effects of the present invention will be explained in more detail below based on examples and comparative examples. However, these examples are intended to explain the present invention more specifically, and the scope of the present invention is not limited to these examples.

Examples Example 1
Lyocell tow with a tow fiber bundle of approximately 35,000 denier was used, using lyocell fibers with a fiber diameter of approximately 3.0 denier. A binder solution, a mixture of a binder and a solvent, was prepared. Specifically, the binder solution was prepared by adding 10 wt% polyester (a copolymer of phthalic acid, sebacic acid, and ethylene glycol, weight-average molecular weight ( _Mw ) = 3,000-6,000) based on the total weight of the binder solution to 90 wt% solvent (a mixed solvent of 30 wt% propylene glycol, 10 wt% ethanol, and 50 wt% water). The prepared binder solution was sprayed onto the lyocell tow using a nozzle spray. The binder solution was sprayed at 15 wt% based on the weight of the lyocell tow and stored at room temperature for 6 hours to prepare binder-containing lyocell tow. The produced lyocell tow was wrapped in a cigarette paper to produce a cigarette filter having an axial length of about 108 mm and a circumference of about 24.20 mm.

Example 2
Cigarette filters were prepared in the same manner as in Example 1, except that 3% by weight of polyester and 7% by weight of hydroxypropylmethylcellulose (Pharmacoat 606) were used in place of 10% by weight of polyester in the binder solution.

Example 3
A cigarette filter was produced in the same manner as in Example 2, except that a 90 wt% solvent (a mixed solvent of 30 wt% propylene glycol, 30 wt% ethanol, and 30 wt% water) was used as the solvent for the binder solution instead of a 90 wt% solvent (a mixed solvent of 30 wt% propylene glycol, 10 wt% ethanol, and 50 wt% water).

Comparative Example 1
Cigarette filters were produced without spraying the lyocell tow with a binder solution.

Comparative Example 2
A cigarette filter was produced in the same manner as in Example 1, except that 90 wt % water was used as the solvent for the binder solution instead of the 90 wt % solvent (a mixed solvent of 30 wt % propylene glycol, 10 wt % ethanol, and 50 wt % water).

Comparative Example 3
A cigarette filter was produced in the same manner as in Example 2, except that 90 wt % water was used as the solvent for the binder solution instead of the 90 wt % solvent (a mixed solvent of 30 wt % propylene glycol, 10 wt % ethanol, and 50 wt % water).

Experimental Examples Experimental Example 1: Evaluation of Hardness of Cigarette Filters The hardness of the cigarette filters manufactured in Examples 1 to 3 and Comparative Examples 1 to 3 was measured. Specifically, the hardness of the cigarette filters was measured using a filter hardness tester (DHT 200 ^™ manufactured by Filtrona) and the following calculation formula 1:

[Formula 1]
Filter hardness (%) = [Da]/D x 100

Here, D is the filter diameter, and a is the distance (mm) that the 300g weight moves down (presses the filter).

As shown in Table 1, when a binder solution containing a polyhydric alcohol is used as a solvent for the binder, excellent hardness of 85% or more can be achieved by storing the product at room temperature for just 6 hours, without the need for long-term drying at high temperatures. This not only significantly shortens the drying time, but also minimizes changes in hardness due to drying, ensuring stable hardness and helping to improve processability and productivity in the manufacture of cigarette filters.

In addition, when a monohydric alcohol is used together with a polyhydric alcohol, the water content can be significantly reduced, preventing the phenomenon in which the functionality of the binder is not fully expressed due to water in the initial stage of spraying the binder solution, as seen in Comparative Examples 2 and 3.

In addition, the polyhydric alcohol contained in the binder solution acts as a release agent when applied to subsequent rolling processes, preventing the lyocell tow from getting caught in the roll. The monohydric alcohol is a more volatile component than water, and an appropriate amount remains in the cigarette filter, providing additional functionality such as sterilization.

While the above embodiments have been described using limited examples and drawings, those skilled in the art will appreciate that various modifications and variations may be made to the above description. For example, the described techniques may be performed in a different order than described, and/or the components of the described systems, structures, devices, circuits, etc. may be combined or combined in a different manner than described, or may be substituted or replaced by other components or equivalents, and still achieve suitable results.

10 smoking material portion 20 filter portion 30a smoking material portion wrapper 30b filter portion wrapper 40 tipping paper 100 smoking article

Claims (14)

a lyocell tow made of a plurality of lyocell fibers;
a binder that binds the lyocell fibers together;
a solvent dispersed in the inner space of the cigarette filter containing the lyocell tow,
The cigarette filter, wherein the solvent comprises a polyhydric alcohol. The cigarette filter according to claim 1, wherein the polyhydric alcohol is a diol having a C1 to C4 alkylene group. 2. The cigarette filter according to claim 1, wherein the polyhydric alcohol is propylene glycol. 2. The cigarette filter according to claim 1 , wherein the polyhydric alcohol is contained in an amount of 0.5 to 25 parts by weight based on 100 parts by weight of the lyocell tow . The cigarette filter according to claim 1, wherein the binder is hydroxypropyl methylcellulose, hydroxypropyl cellulose, polyvinyl alcohol, ethylene vinyl acetate, polyvinyl acetate, polyvinylpyrrolidone, polyester, or a combination thereof. 2. The cigarette filter according to claim 1 , wherein the binder is contained in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the lyocell tow . The cigarette filter according to claim 1, wherein the solvent further contains a monohydric alcohol selected from the group consisting of methanol, ethanol, propanol, and combinations thereof. 1. A method for manufacturing a cigarette filter, the method comprising :
Spraying a binder solution prepared by mixing a binder and a solvent onto a lyocell tow prepared using a plurality of lyocell fibers , and storing the lyocell tow so that the plurality of lyocell fibers can be bound to each other by the binder ;
and wrapping the lyocell tow, in which the plurality of lyocell fibers are bound by the binder , with a wrapping paper to manufacture the cigarette filter ,
The method for producing a cigarette filter, wherein the solvent contains a polyhydric alcohol. manufacturing the lyocell tow using the plurality of lyocell fibers;
The method for manufacturing a cigarette filter according to claim 8, further comprising the step of: mixing the binder and the solvent to prepare the binder solution. The method for producing a cigarette filter according to claim 8 , wherein the polyhydric alcohol is contained in an amount of 5 to 50 parts by weight based on 100 parts by weight of the binder solution. The method for producing a cigarette filter according to claim 8 , wherein the solvent further contains a monohydric alcohol. 12. The method for producing a cigarette filter according to claim 11 , wherein the monohydric alcohol is methanol, ethanol, propanol, or a combination thereof. The method for producing a cigarette filter according to claim 11 , wherein the monohydric alcohol is contained in an amount of 5 to 60 parts by weight based on 100 parts by weight of the binder solution. 9. The method for manufacturing a cigarette filter according to claim 8 , wherein the binder solution is sprayed onto the lyocell tow in an amount of 5 to 30 parts by weight based on 100 parts by weight of the lyocell tow .