WO2017168516A1

WO2017168516A1 - Filter for smoking article, smoking article, and process for producing filter for smoking article

Info

Publication number: WO2017168516A1
Application number: PCT/JP2016/059916
Authority: WO
Inventors: 龍北岡; 正人宮内
Original assignee: 日本たばこ産業株式会社
Priority date: 2016-03-28
Filing date: 2016-03-28
Publication date: 2017-10-05
Also published as: JPWO2017168516A1; JP6535810B2; EP3400814A1; EP3400814A4

Abstract

A filter for smoking articles which includes composite particles configured of core particles having an average particle diameter of 200-1,000 µm and nanoparticles fixed to at least some of the surface of the core particles, the nanoparticles comprising a hydrotalcite compound and having an average particle diameter of 200 nm or smaller.

Description

Filter for smoking article, smoking article, and method for producing filter for smoking article

The present invention relates to a filter for smoking articles, a smoking article, and a method for manufacturing a filter for smoking articles.

For smoking articles such as cigarettes, adsorbent particles are added to the filter to adsorb and remove chemical components in mainstream smoke. Activated carbon particles are typically used as the adsorbent particles, but the use of various adsorbent particles has been attempted. For example, it has been reported that hydrotalcite particles having an average particle size of 200 to 800 μm are added to a cigarette filter to selectively remove formaldehyde in mainstream smoke (Patent Document 1).

International Publication No. 2003/056947

Generally, it is known that when the particle size of the adsorbent particles is reduced to increase the specific surface area, the adsorption ability is improved. The inventors of the present invention reduced the particle size of hydrotalcite particles to the nano level and added it to the cigarette filter, and tried to improve the adsorption capacity. I found a problem that it is not suitable.

Therefore, an object of the present invention is to provide a filter for smoking articles that can more effectively remove formaldehyde in mainstream smoke without excessively increasing the airflow resistance.

According to one aspect of the invention,
Core particles having an average particle size of 200 μm to 1000 μm;
Provided is a filter for smoking articles comprising composite particles that are supported on at least a part of the surface of the core particle, are composed of a hydrotalcite compound, and are composed of nanoparticles having an average particle size of 200 nm or less. .

According to another aspect, there is provided a smoking article including such a smoking article filter and a tobacco rod connected to one end of the smoking article filter.

According to yet another aspect,
Stirring a suspension containing core particles having an average particle size of 200 μm to 1000 μm and hydrotalcite particles having an average particle size of 200 nm or less in water, and then drying the suspension to obtain the core particles A method for producing a filter for smoking articles, comprising preparing composite particles having the hydrotalcite particles supported on at least a part of a surface of the surface, and incorporating the obtained composite particles into a filter for smoking articles. Provided.

According to the present invention, formaldehyde in mainstream smoke can be more effectively removed without excessively increasing the airflow resistance.

The figure which shows typically an example of the composite particle comprised from a core particle and a nanoparticle. The disassembled perspective view which shows an example of the filter of this invention. The graph which shows the filter ventilation resistance of a composite particle containing filter and a nanoparticle containing filter. The graph which shows the filter ventilation resistance of a composite particle containing filter and a core particle containing filter. The figure which shows typically the cigarette produced in the Example. The figure which shows the measuring apparatus of formaldehyde in a cigarette mainstream smoke. The graph which shows the formaldehyde reduction rate of a cigarette. The graph which shows the adhesive force to the core particle of a hydrotalcite particle. The graph which shows the relationship between the particle size of hydrotalcite particle | grains, and formaldehyde adsorption rate. The graph which shows the relationship between the particle size of hydrotalcite particle | grains, and ventilation resistance.

Hereinafter, the present invention will be described, but the following description is intended to explain the present invention in detail and is not intended to limit the present invention.

The filter for smoking articles of the present invention is
Core particles having an average particle size of 200 μm to 1000 μm;
The composite particle | grains carry | supported on at least one part of the surface of the said core particle, consisting of a hydrotalcite type compound, and comprised from the nanoparticle which has an average particle diameter of 200 nm or less are included.

FIG. 1 schematically shows an example of a composite particle 11 composed of core particles 11a and nanoparticles 11b. As shown in FIG. 1, the nanoparticles 11b are supported on at least a part of the surface of the core particles 11a.

The core particles preferably have a function as adsorbent particles. When the core particles have a function as adsorbent particles, it is preferable that the nanoparticles do not cover the entire surface of the core particles. When the core particle functions as an adsorbent particle and has pores on the surface thereof, the nanoparticle may enter the pore, but at least a part of the nanoparticle is fine. It is preferably supported on the surface of the core particle excluding the pore surface.

In order for the core particles to efficiently attach the nanoparticles to the surface, the core particles preferably have water retention. Water retention refers to the property of retaining water on the surface of the core particles. Specifically, water retention refers to the property of retaining water on the surface of the core particle by making the surface of the core particle hydrophilic and / or porous.

The water retention of the core particles can be quantified by the water retention rate defined below.

1 g of core particles are immersed in 10 mL of water, and after 1 minute, filtration is performed using a metal mesh (0.1 mm) to separate the core particles and water. The weight of the separated core particles is measured. From the measured weight, the water retention rate of the core particles is determined by the following equation.
Water retention (%) = [{(weight of core particles after passing through metal mesh) − (weight of core particles before being immersed in water)} / (weight of core particles before being immersed in water)] × 100

The core particles preferably have a water retention rate of 70% or more, more preferably 70 to 150%, and still more preferably 70 to 100%.

For example, porous particles can be used as the core particles. More specifically, as the porous particles, porous particles used as an adsorbent in a filter for smoking articles, for example, activated carbon particles, silica particles, hydrotalcite particles, calcium phosphate particles, zeolite particles, etc. may be used. it can. Preferably, activated carbon particles are used as the porous particles. The activated carbon particles preferably have a BET specific surface area of 400-2800 m ² / g. Non-porous particles can also be used as the core particles, such as calcium carbonate particles, saccharide particles (eg, particles composed of monosaccharides, disaccharides, oligosaccharides, polysaccharides, or any combination thereof), Cellulose particles, cellulose triacetate particles, and the like can be used.

The core particles have an average particle size of 200 μm to 1000 μm, preferably an average particle size of 300 μm to 700 μm, more preferably an average particle size of 400 μm to 600 μm. In this specification, the average particle diameter of the core particles refers to a value measured using a digital image of particles photographed by a CCD camera. For example, an image analysis type particle size distribution measuring device (Camsizer, Retsch technology) is used. Refers to the measured value. The average particle diameter of the nanoparticles refers to a value measured using a transmission electron microscope (TITAN 80-300, FEI). The average particle diameter of the core particles and nanoparticles can be obtained by randomly selecting a statistically sufficient number (for example, 30 particles), measuring the particle diameter, and calculating the arithmetic average. The average particle size of the composite particles can be measured in the same manner as the core particles.

The nanoparticles have an average particle diameter of 1 to 200 nm, preferably 10 nm to 150 nm, more preferably 10 nm to 50 nm. The nanoparticles are made of a hydrotalcite compound.

The hydrotalcite compound constituting the nanoparticles has a layered structure in which a large number of octahedral layers of metal hydroxide are laminated, and anions are intercalated between these layers. The octahedral layer is called a host and exhibits basicity. Formaldehyde removal by hydrotalcite-type compounds is considered to occur as a result of the basic contribution of the host and the ion exchange action by intercalated anions. The hydrotalcite compound may be natural or synthetic.

Hydrotalcite compounds have the following general formula [M 2 ⁺ _1-x M ³⁺ _x (OH) ₂ ] [(A ⁿ⁻ ) _{x / n} · m H ₂ O]
(Wherein, M ²⁺ is a divalent metal ion selected from the group consisting of Mg, Zn, Ni and Ca, M ³⁺ is Al ion, A ^n-is CO _3, SO ₄ , OOC-COO, Cl, Br, F, NO ₃ , Fe (CN) ₆ ³⁻ , Fe (CN) ₆ ⁴⁻ , phthalic acid, isophthalic acid, terephthalic acid, maleic acid, alkenyl acid and derivatives thereof, apple An n-valent anion selected from the group consisting of acid, salicylic acid, acrylic acid, adipic acid, succinic acid, citric acid and sulfonic acid, x is 0.1 <x <0.4, and m is 0 < m <2).

In the general formula, M ²⁺ is Mg ion, M ³⁺ is Al ion, A ^n-is CO ₃ ^2-or SO ₄ is ^2-, x is 0.1 <x < 0.4 and m is preferably 0 <m <2. Such Mg—Al based hydrotalcite compounds are stable when x is in the range of 0.20 to 0.33. Most preferably, the general formula is Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O.

Mg-Al-based hydrotalcite compounds are obtained by adding alkali carbonate or alkali carbonate and caustic alkali to an aqueous solution of water-soluble aluminum salt or aluminate and water-soluble magnesium salt selected from aluminum sulfate, aluminum acetate and alum. The reaction mixture can be produced by maintaining the pH of the reaction mixture at 8.0 or higher. By pulverizing and classifying the obtained hydrotalcite compound, nanoparticles having an average particle diameter of 200 nm or less can be obtained.

As the core particles and nanoparticles, those prepared according to a known method may be used, or commercially available products may be used.

Composite particles composed of core particles and nanoparticles can be prepared as described below. By stirring the suspension containing the nanoparticles and the core particles in water, and then drying the suspension, composite particles in which the nanoparticles are supported on the surface of the core particles can be prepared.

As the core particles and nanoparticles, those described above can be used. The core particles preferably have a water retention of 70% or more, more preferably 70 to 150%, and still more preferably 70 to 100%. The higher the water retention rate (that is, the higher the ability to retain water on the surface), the higher the nanoparticle loading rate. This is because the core particles and the nanoparticles are bonded together in the suspension mainly by the liquid cross-linking adhesion force, so that the higher the water retention rate of the core particles, the larger the liquid cross-linking adhesion force. On the other hand, if the water retention rate is too high, the composite particles agglomerate with each other and uniform addition to the filter becomes difficult. Therefore, a water retention rate of 70 to 100% is particularly desirable in terms of production suitability. Further, after the suspension is dried, the nanoparticles are supported on the surface of the core particles mainly by van der Waals force, and the adhesion thereof is maintained.

In the preparation of the composite particles, the core particles and the nanoparticles are mixed in a weight ratio of, for example, 1000: 1 to 1: 1, preferably 100: 1 to 2: 1. When mixing 20 mg of core particles and 10 mg of nanoparticles, these particles can be added to, for example, 30-1000 μL of water to prepare a suspension. Such a suspension can be dried at 80 to 200 ° C. for 5 to 120 minutes to obtain a sample containing composite particles. Drying is preferably performed until the entire amount of moisture is removed.

When all of the used nanoparticles are not supported on the core particles, the sample includes nanoparticles that are not supported on the core particles. In this case, the composite particles and the nanoparticles may be separated using a sieve.

When the ratio (support rate) of the nanoparticles supported on the core particles is low, the treatment for supporting the nanoparticles on the core particles may be repeated. Specifically, after preparing the composite particles, the composite particles and the nanoparticles are separated using a sieve, the separated nanoparticles are suspended in water, and the resulting suspension is separated from the separated composite particles. Mix and dry. This allows additional nanoparticles to be further attached to the composite particles. By carrying out this operation repeatedly, the loading rate can be increased.

The composite particles can be generally added to a filter having a diameter of 7.7 mm and a length of 27 mm in an amount of 10 to 100 mg, preferably 15 to 40 mg. The composite particles can generally be added to account for 3 to 33% of the total volume of the filter, preferably 5 to 13% of the total volume of the filter.

The composite particles can be incorporated into a smoking article filter to produce various forms of smoking article filters as follows.
(1) A filter in which composite particles are dispersed in a filter medium, for example, a fiber tow or non-woven fabric such as cellulose acetate.
(2) A filter formed from a paper sheet obtained by adding composite particles to a raw material and making paper.
(3) A filter comprising two or more segments, wherein at least one segment comprises the filter of (1) or (2). In this case, the other segment can be a conventional cellulose acetate filter or charcoal filter.
(4) A filter in which composite particles are filled in a space (filter cavity portion) between two or more filter plugs arranged apart from each other. In this case, the filter plug may be a conventional cellulose acetate filter or charcoal filter, or may be the filter of (1) or (2). Further, when there are two or more spaces, at least one space may be filled with composite particles, and the other spaces may be filled with activated carbon particles. An example of this filter is shown in FIG.

In the filter 10 shown in FIG. 2, the composite particles 11 are arranged in a space (filter cavity portion) between two filter plugs 12 arranged apart from each other, and plugs are provided around the two filter plugs 12. A web 13 is wound.

In the following description, a filter in which composite particles are incorporated is also referred to as a composite particle-containing filter. The composite particle-containing filter can be incorporated into any smoking article, specifically a combustible smoking article that burns tobacco filler, such as cigarette, or a non-combustible suction article that does not burn tobacco filler, such as heating It can be incorporated into a mold aspirator. Reference can be made, for example, to WO 2006/073065 or WO 2010/110226 for a heated suction device. For example, a tobacco rod containing a tobacco filler can be connected to one end of a composite particle-containing filter to produce a combustion-type smoking article such as a cigarette. Alternatively, for example, a non-combustible smoking article, for example, a heated aspirator, can be produced by arranging a composite particle-containing filter at one or both ends of a cylindrical member forming a cavity and arranging a flavor source in the cavity. it can.

Compared with a filter to which nanoparticles are directly added, the composite particle-containing filter is less likely to increase the filter ventilation resistance (see Experiment 1 described later). When the composite particles are added in an amount of 10 to 100 mg to a filter having a diameter of 7.7 mm and a length of 27 mm, the composite particle-containing filter can exhibit a filter ventilation resistance of, for example, 40 to 80 mmH ₂ O. Thus, when the composite particle-containing filter exhibiting the filter ventilation resistance is incorporated in a cigarette, the obtained cigarette can exhibit a cigarette ventilation resistance of, for example, 80 to 120 mmH ₂ O.

In addition, when the composite particle-containing filter is incorporated in a cigarette, the obtained cigarette can more effectively remove formaldehyde in the mainstream smoke (see Experiment 2 described later).

Experiment 1: Filter ventilation resistance (1-1) Preparation of composite particle-containing filter Activated carbon particles (average particle size: 400 μm; BET specific surface area: 1252 m ² / g) and hydrotalcite particles (Mg ₆ Al ₂ (OH) ₁₆ CO ₃ · 4H ₂ O, average particle size: 50 nm; BET specific surface area: 111.5 m ² / g) was supported to prepare hydrotalcite-supported activated carbon (hereinafter also referred to as composite particles). Specifically, the support of the hydrotalcite particles on the activated carbon particles was performed as follows. 40 μL of water was added to a mixture of 20 mg of activated carbon particles and 10 mg of hydrotalcite particles, and this was stirred until the activated carbon particles and hydrotalcite particles were uniformly mixed to obtain a slurry sample. The resulting slurry sample was dried in an oven (100 ° C., 60 minutes) and then conditioned for 48 hours under conditions of a temperature of 22 ° C. and a humidity of 60% to obtain composite particles.

The obtained composite particles were placed in a space (filter cavity part) between two filter plugs (filter medium: acetate tow; diameter: 7.7 mm; length: 5 mm) spaced apart from each other, A composite particle-containing filter was produced by winding a plug web around the filter plug (see FIG. 5).

(1-2) Preparation of nanoparticle-containing filter Hydrotalcite particles (Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O, average particle size: 50 nm; BET specific surface area: 111.5 m ² / g) Nanoparticles are placed in a space (filter cavity part) between two filter plugs (filter medium: acetate tow; diameter: 7.7 mm; length: 5 mm) and a plug web is wound around the filter plug. A containing filter (Comparative Example 1) was produced.

(1-3) Preparation of Core Particle-Containing Filter Activated carbon particles (average particle size: 400 μm; BET specific surface area: 1252 m ² / g) were passed through two filter plugs (filter medium: acetate tow; diameter: 7.7 mm; length: 5 mm), a core particle-containing filter (Comparative Example 2) was manufactured by winding a plug web around the filter plug.

(1-4) Measurement of filter ventilation resistance The filter ventilation resistance was measured according to ISO 6565: 2015 Draw resistance of cigarettes and pressure drop of filter rods.

(1-5) Results FIG. 3 shows the filter ventilation resistance of the composite particle-containing filter and the nanoparticle-containing filter. FIG. 4 shows the filter ventilation resistance of the composite particle-containing filter and the core particle-containing filter.

In FIG. 3, the addition amount on the horizontal axis indicates the addition amount (mg) of hydrotalcite particles (nanoparticles). Moreover, in FIG. 3, the filter ventilation resistance of a composite particle containing filter shows the value calculated by the following formula | equation.
(Filter ventilation resistance of a filter containing composite particles) = (Filter ventilation resistance measured using a filter containing composite particles) − (Measured using a filter containing activated carbon particles in the same amount as the activated carbon particles used in the filter containing composite particles) Filter ventilation resistance)
Moreover, in FIG. 3, the filter ventilation resistance of a nanoparticle containing filter shows the value calculated by the following formula | equation.
(Filter ventilation resistance of the nanoparticle-containing filter) = (Filter ventilation resistance measured using a nanoparticle-containing filter) − (Filter ventilation resistance measured using a filter not containing nanoparticles).

In FIG. 4, the addition amount on the horizontal axis indicates the addition amount (mg) of composite particles or activated carbon particles. Moreover, in FIG. 4, the filter ventilation resistance of the composite particle containing filter shows the value calculated by the following formula | equation.
(Filter ventilation resistance of a filter containing composite particles) = (Filter ventilation resistance measured using a filter containing composite particles) − (Filter ventilation resistance measured using a filter not containing composite particles)
Moreover, in FIG. 4, the filter ventilation resistance of a core particle containing filter shows the value calculated by the following formula | equation.
(Filter ventilation resistance of filter containing core particles) = (Filter ventilation resistance measured using a filter containing core particles) − (Filter ventilation resistance measured using a filter containing no core particles).

The following can be understood from the results of FIG. When hydrotalcite particles having an average particle diameter of 50 nm are directly added to the filter, the filter ventilation resistance is remarkably increased according to the amount of the hydrotalcite particles added. On the other hand, when hydrotalcite particles having an average particle size of 50 nm are added to the filter in the form of hydrotalcite-supported activated carbon (composite particles), the presence of the hydrotalcite particles does not greatly increase the filter ventilation resistance.

From the results shown in FIG. When hydrotalcite particles with an average particle size of 50 nm are added to the filter in the form of hydrotalcite-supported activated carbon (composite particles), such a filter exhibits a filter ventilation resistance equivalent to a filter to which the same amount of activated carbon particles are added. The presence of talcite particles does not greatly increase the filter ventilation resistance.

From these results, when hydrotalcite particles having an average particle size of 50 nm are added to the filter in the form of hydrotalcite-supported activated carbon (composite particles), the presence of hydrotalcite particles is higher than when added directly to the filter. It can be seen that it is difficult to increase the filter ventilation resistance.

Experiment 2: Formaldehyde reduction rate (2-1) Production of cigarette of the present invention A composite particle-containing filter was produced in the same manner as in Experiment 1. The produced composite particle-containing filter was connected to a tobacco rod (diameter: 7.7 mm; length: 57 mm; tobacco filler: 605 mg) to produce a cigarette of the present invention. The connection was performed so as to cover the connection part with chip paper (not shown). The produced cigarette of this invention is typically shown in FIG.

In FIG. 5, the filter 10 is composed of two filter plugs 12 that are spaced apart from each other, a plug web 13 wound around the filter plug 12, and composite particles 11 that are disposed between the filter plugs 12. . The tobacco rod 20 includes a tobacco filler 21 and a cigarette paper 22 wound around the tobacco filler 21.

(2-2) Preparation of Cigarette of Comparative Example Instead of hydrotalcite-supported activated carbon (composite particles), 10 mg of hydrotalcite particles (Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O, average particle size: A cigarette of a comparative example was produced in the same manner as the cigarette of the present invention except that 700 μm; BET specific surface area: 103.8 m ² / g) was used. The hydrotalcite particles having an average particle size of 700 μm correspond to the adsorbent particles used in the prior art document (WO2003 / 056947).

(2-3) Measurement of formaldehyde in mainstream smoke The amount of formaldehyde in mainstream smoke was measured by the official Canadian method (2,4-DNPH-HPLC method) to determine the reduction rate of formaldehyde.

First, 9.51 g of 2,4-dinitrophenylhydrazine (DNPH) was dissolved by heating in 1 L of acetonitrile, and then 5.6 mL of 60% perchloric acid was added, and ultrapure water was added to add 2 L of collected liquid. Prepared.

The outline of the measuring apparatus will be described with reference to FIG. As shown in FIG. 6, the DNPH collection liquid 32 is put into the collection air washing bottle 31. The capacity of the washing bottle 31 was 100 mL, and the amount of the DNPH collection liquid 32 was 80 mL. The air bottle 31 is placed in an ice water bath 33 and cooled with ice. The lower end of the glass tube 34 to which the cigarette 30 is attached is immersed in the collected liquid 32 in the air cleaning bottle 31. The glass tube 35 and the Cambridge pad 36 are attached so as to communicate with the dead volume of the air cleaning bottle 31, and the Cambridge pad 36 and the automatic smoker 37 are connected.

The cigarette 30 is attached to the glass tube 34, and the cigarette 30 is automatically smoked under standard ISO smoking conditions. That is, for each cigarette, the operation of sucking 35 mL of smoke for 2 seconds with one empty puff is repeated at intervals of 58 seconds. While mainstream smoke is bubbled, formaldehyde is derivatized by DNPH. Two cigarettes for measurement were used. At this time, the pressure loss was adjusted to be the same for each cigarette using any adsorbent particle.

The derivative produced as described above is measured by high performance liquid chromatography (HPLC). First, the collected liquid is filtered and then diluted with the Trizma Base solution (collected liquid 4 mL, Trizma Base solution 6 mL). This solution is measured by HPLC. The HPLC measurement conditions are as follows.
Column: HP LiChropher 100RP-18 (5μ) 250 × 4 mm
Guard column: HP LiChropher 100RP-18 (5μ) 4x4mm
Column temperature: 30 ° C
Detection wavelength: DAD 356 nm
Injection volume: 20 μL
Mobile phase: gradient by three phases (liquid A: ultrapure water aqueous solution containing 30% acetonitrile, 10% tetrahydrofuran and 1% isopropanol, liquid B: ultrapure water containing 65% acetonitrile, 1% tetrahydrofuran and 1% isopropanol Aqueous solution, solution C: acetonitrile 100%).

As a control experiment, the amount of formaldehyde in mainstream smoke was measured for cigarettes (hereinafter referred to as control cigarettes) equipped with a filter containing neither hydrotalcite-supported activated carbon (composite particles) nor hydrotalcite particles (average particle size: 700 μm). did.

The formaldehyde reduction rate was determined by substituting the measured formaldehyde amount into the following equation.
(Formaldehyde reduction rate) = [{(formaldehyde amount measured with control cigarette) − (formaldehyde amount measured with cigarette of the present invention or comparative cigarette)} / (formaldehyde amount measured with control cigarette)] × 100

(2-4) Results The formaldehyde (FA) reduction rate of the cigarette of the present invention and the cigarette of the comparative example is shown in FIG.

FIG. 7 shows that hydrotalcite-supported activated carbon (composite particles) can effectively remove formaldehyde in mainstream smoke as compared to hydrotalcite particles having an average particle size of 700 μm.

Experiment 3: Adhesive force of hydrotalcite particles to core particles (3-1) Preparation of hydrotalcite-supported particles The following core particles A to C were used as core particles.
Core particle A: activated carbon particle (average particle diameter: 400 μm; BET specific surface area: 1252 m ² / g)
Core particle B: Hydrotalcite particle (Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O, average particle size: 700 μm; BET specific surface area: 103.8 m ² / g)
Core particle C: cellulose triacetate granule (average particle size: 400 μm; particles described in Japanese Patent No. 5786038)
Core particle A and core particle B are porous particles.

100 mg of hydrotalcite particles (Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O, average particle size: 50 nm; BET specific surface area: 111.5 m ² / g) are suspended in 500 μL of water, and 1 g of core particles And stirred until the hydrotalcite particles and the core particles were uniformly mixed to obtain a slurry sample. The obtained slurry sample was dried in an oven (100 ° C., 60 minutes) to prepare hydrotalcite-supported particles (composite particles). The hydrotalcite-supported particles obtained using the core particles A are referred to as composite particles A, and the hydrotalcite-supported particles obtained using the core particles B are referred to as composite particles B, using the core particles C. The obtained hydrotalcite-supported particles are referred to as composite particles C.

Further, 100 mg of hydrotalcite particles (Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O, average particle size: 50 nm; BET specific surface area: 111.5 m ² / g) were shaken with 1 g of core particles A. The mixture was mixed well using a stirrer to prepare hydrotalcite-supported particles (composite particles). This composite particle is referred to as composite particle D.

(3-2) Measurement of water retention rate 1 g of core particles was immersed in 10 mL of water, and after 1 minute, filtration was performed using a metal mesh (0.1 mm) to separate the core particles and water. The weight of the separated core particles was measured. From the measured weight, the water retention rate of the core particles was determined by the following equation.
Water retention (%) = [{(weight of core particles after passing through metal mesh) − (weight of core particles before being immersed in water)} / (weight of core particles before being immersed in water)] × 100

(3-3) Measurement of adhesion force The adhesion force of hydrotalcite particles to the core particles was measured as follows.

In the case of composite particles A to C: 100 mg of hydrotalcite particles (Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O, average particle size: 50 nm; BET specific surface area: 111.5 m ² / g) in 500 μL of water The mixture was suspended and mixed with 1 g of core particles, and the mixed solution was stirred until the hydrotalcite particles and the core particles were uniformly mixed to obtain a slurry sample. The obtained slurry sample was dried in an oven (100 ° C., 60 minutes). The dried sample was passed through a mesh 0.15 mm screen.

The fine powder that passed through the sieve was suspended in 500 μL of water, added to and mixed with the particles that did not pass through the sieve, and dried in an oven (100 ° C., 60 minutes). The dried sample was screened again. This operation (mixing, drying and sieving operations) was repeated a total of 3 times. Finally, the weight of the fine powder that passed through the sieve was measured.

In the case of the composite particle D: 100 mg of hydrotalcite particles (Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O, average particle size: 50 nm; BET specific surface area: 111.5 m ² / g) Mix well with A and shaker. The resulting mixture was passed through a 0.15 mm mesh screen.

The fine powder that passed through the sieve was added to and mixed with the particles that did not pass through the sieve. The resulting mixture was screened again. This operation (mixing and sieving operation) was repeated a total of 3 times. Finally, the weight of the fine powder that passed through the sieve was measured.

The adhesion force of hydrotalcite particles (average particle size: 50 nm) to the core particles was determined by the following equation.
Adhesive force (%) = {(100 (mg) −weight of fine powder permeated through sieve (mg)) / 100 (mg)} × 100

(3-4) Results The water retention rates of the core particles A to C are shown below.
Core particle A: water retention 95%
Core particle B: water retention 74%
Core particle C: water retention 34%

Fig. 8 shows the adhesive force (%) of hydrotalcite particles (average particle size: 50 nm) to the core particles.

The following can be seen from the results of the water retention rate and the results of FIG. When nanoparticles and core particles having a water retention rate are mixed in the presence of water and the mixture is dried to produce composite particles, the nanoparticles can be supported (attached) to the core particles (composite particles A to C). ). On the other hand, when the nanoparticle and the core particle having a water retention rate are mixed in the absence of water to produce a composite particle, the adhesion rate of the hydrotalcite particle becomes low (composite particle D). From the results of the composite particles A to C, it can be seen that the adhesion rate of the hydrotalcite particles can be increased as the core particles have a higher water retention rate (that is, the higher the ability to retain water on the surface).

Experiment 4: Reference Example The relationship between the particle size of hydrotalcite particles and formaldehyde adsorption rate and the relationship between the particle size of hydrotalcite particles and ventilation resistance were examined.

(4-1) Preparation of hydrotalcite particles Hydrotalcite having a particle size of 100 to 300 μm is obtained by pulverizing and classifying hydrotalcite particles (Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O). Particles, hydrotalcite particles having a particle size of 300 to 500 μm, hydrotalcite particles having a particle size of 500 to 700 μm, and hydrotalcite particles having a particle size of 700 μm or more were prepared.

(4-2) Production of cigarette The obtained hydrotalcite particles were separated from each other by a space between two filter plugs (filter medium: acetate tow; diameter: 7.7 mm; length: 5 mm) ( An adsorbent particle-containing filter was prepared by placing a plug web around the filter plug in the filter cavity portion).

The produced adsorbent particle-containing filter was connected to a tobacco rod (diameter: 7.7 mm; length: 57 mm; tobacco filler: 605 mg) to produce a cigarette (see FIG. 5). The connection was performed so as to cover the connection part with chip paper.

(4-3) Measurement of formaldehyde adsorption rate The amount of formaldehyde in mainstream smoke is measured by the same method as described in Experiment 2, and the formaldehyde adsorption rate is calculated by substituting the measured formaldehyde amount into the following equation. Asked.
(Formaldehyde adsorption rate) = [{(formaldehyde amount measured with control cigarette) − (measured formaldehyde amount)} / (formaldehyde amount measured with control cigarette)]
The control cigarette has the same configuration as the cigarette produced above except that no adsorbent particles were added.

(4-4) Measurement of filter ventilation resistance The filter ventilation resistance was measured by the same method as described in Experiment 1.

(4-5) Results The results of formaldehyde adsorption rate and cigarette ventilation resistance are shown in FIGS. 9 and 10, respectively. The horizontal axis of FIG. 9 represents the amount of hydrotalcite particles added to the filter by volume. The horizontal axis of FIG. 10 represents the amount of hydrotalcite particles added to the filter by weight.

From the results of FIG. 9, it can be seen that when the particle size of the adsorbent particles is reduced, the formaldehyde adsorption ability is improved. From the results of FIG. 10, it can be seen that the airflow resistance increases when the particle size of the adsorbent particles is reduced.

DESCRIPTION OF SYMBOLS 10 ... Filter, 11 ... Composite particle, 11a ... Core particle, 11b ... Nanoparticle, 12 ... Filter plug, 13 ... Plug web, 20 ... Tobacco rod, 21. ..Tobacco filler, 22... Cigarette paper, 30... Cigarette, 31... Air-washing bottle, 32 .. collecting liquid, 33 .. ice water bath, 34. ... Glass tube, 36 ... Cambridge pad, 37 ... Automatic smoker

Claims

Core particles having an average particle size of 200 μm to 1000 μm;
A filter for a smoking article comprising composite particles which are supported on at least a part of the surface of the core particles and which are composed of a hydrotalcite compound and composed of nanoparticles having an average particle diameter of 1 to 200 nm.
The filter for smoking articles according to claim 1, wherein the core particles have water retention.
The filter for smoking articles according to claim 2, wherein the core particles have a water retention rate of 70% or more.
The filter for smoking articles according to claim 2 or 3, wherein the core particles are porous particles.
The filter for smoking articles according to claim 4, wherein the porous particles are activated carbon particles.
The nanoparticles have the general formula:
[M 2+ 1-x M 3+ x (OH) 2 ] [(A n− ) x / n · m H 2 O]
(Wherein, M 2+ is a divalent metal ion selected from the group consisting of Mg, Zn, Ni and Ca, M 3+ is Al ion, A n-is CO 3, SO 4 , OOC-COO, Cl, Br, F, NO 3 , Fe (CN) 6 3− , Fe (CN) 6 4− , phthalic acid, isophthalic acid, terephthalic acid, maleic acid, alkenyl acid and derivatives thereof, apple An n-valent anion selected from the group consisting of acid, salicylic acid, acrylic acid, adipic acid, succinic acid, citric acid and sulfonic acid, x is 0.1 <x <0.4, and m is 0 < The filter for smoking articles according to any one of claims 1 to 5, comprising a hydrotalcite compound represented by m <2.
In the general formula, M 2+ is Mg ion, M 3+ is Al ion, A n-is CO 3 2-or SO 4 is 2-, x is 0.1 <x < The filter for smoking articles according to claim 6, wherein 0.4 and m are 0 <m <2.
The filter for smoking articles according to claim 6, wherein the general formula is Mg 6 Al 2 (OH) 16 CO 3 .4H 2 O.
The filter for smoking articles according to any one of claims 1 to 8, wherein the average particle size of the core particles is 300 µm to 700 µm, preferably 400 µm to 600 µm.
The filter for smoking articles according to any one of claims 1 to 9, wherein an average particle diameter of the nanoparticles is 10 nm to 150 nm, preferably 10 nm to 50 nm.
A smoking article comprising the smoking article filter according to any one of claims 1 to 10 and a tobacco rod connected to one end of the smoking article filter.
A suspension comprising a hydrotalcite compound-containing nanoparticle having an average particle diameter of 1 to 200 nm and core particles having an average particle diameter of 200 μm to 1000 μm in water is stirred, and then the suspension A composite article having the nanoparticles supported on at least a part of the surface of the core particle, and incorporating the resulting composite particle into a filter for a smoking article. Method for manufacturing filters.