EP3949765A1

EP3949765A1 - Method for manufacturing carbon heat source for flavor inhalation tool, composite particles, carbon heat source for flavor inhalation tool, and flavor inhalation tool

Info

Publication number: EP3949765A1
Application number: EP19922582.2A
Authority: EP
Inventors: Atsuro Yamada; Takashi Oda; Kenta Mitsuchi; Masaki Watanabe
Original assignee: Japan Tobacco Inc
Current assignee: Japan Tobacco Inc
Priority date: 2019-04-04
Filing date: 2019-04-04
Publication date: 2022-02-09
Also published as: WO2020202528A1; CN113543667A; JPWO2020202528A1; EP3949765A4; JP7176101B2

Abstract

A method for manufacturing a carbon heat source for a flavor inhalation tool, said method comprising: forming composite particles, which have an average particle diameter D50 of 10-150 µm and a half-value width of 10-150 µm, with the use of, as a starting material, a slurry containing carbon particles, calcium carbonate particles, a binder and water; molding a mixture containing the composite particles and water to give a molded article; and drying the molded article.

Description

FIELD

The present invention relates to a method for manufacturing a carbon heat source for a flavor inhaler, composite particles, a carbon heat source for a flavor inhaler, and a flavor inhaler.

BACKGROUND

There is known a flavor inhaler that includes a carbon heat source at a distal end and heats a tobacco filler by combustion heat of the carbon heat source. A carbon heat source used for a flavor inhaler can be manufactured by extruding and molding a raw material slurry containing carbon particles and an additive such as a binder, followed by drying.
Jpn. Pat. Appln. KOKAI Publication No. S62-224276 discloses an improved method for manufacturing a carbon heat source for the purpose of improvement on combustibility of a carbon heat source. Specifically, Jpn. Pat. Appln. KOKAI Publication No. S62-224276 discloses, as illustrated in FIG. 1 of the present application, that a carbon heat source 5 is manufactured by spreading a raw material slurry 1 that contains carbon particles la and an aqueous solution (dispersion medium) 1b containing a binder into a sheet shape, drying it, pulverizing the obtained sheet 2, adding water to the obtained pulverized product 3, molding it, and drying the obtained molded article 4.
WO 2006/073065 discloses manufacturing a carbon heat source from a composition containing carbon particles, calcium carbonate particles, and a binder, and that the carbon heat source is capable of reducing the amount of carbon monoxide generated at the time of combustion of the carbon heat source.

SUMMARY

TECHNICAL PROBLEM

The present inventors manufactured a carbon heat source according to the method described in Jpn. Pat. Appln. KOKAI Publication No. S62-224276 , and they encountered the problem in which molding was difficult. In view of this, they carried out molding by increasing the amount of water added at the time of molding (for example, 34% by mass with respect to the pulverized product), resulting in the molding material adhering to the molding machine (see Comparative Example 1 described later). When water was added in an amount generally used at the time of molding (for example, 30% by mass with respect to the pulverized product), molding was difficult, and while the obtained carbon heat source did not have a problem in ignitability, the strength was not sufficient (see Comparative Example 2 described later).
Accordingly, an object of the present invention is to provide a technique relating to a carbon heat source for a flavor inhaler that is excellent in ease of manufacturing, and has a high strength and excellent ignitability.

SOLUTION TO PROBLEM

According to a first aspect, there is provided a method for manufacturing a carbon heat source for a flavor inhaler, in which the method includes:

forming composite particles which have an average particle diameter D50 of 10-150 µm and a half-value width of 10-150 µm, with the use of, as a starting material, a slurry containing carbon particles, calcium carbonate particles, a binder, and water;
molding a mixture containing the composite particles and water to give a molded article; and
drying the molded article.

According to a second aspect, there are provided composite particles comprising carbon particles, calcium carbonate particles, and a binder, and having an average particle diameter D50 of 10 to 150 µm and a half-value width of 10 to 150 µm.
According to a third aspect, there is provided a carbon heat source for a flavor inhaler obtainable by the method according to the first aspect.
According to a forth aspect, there is provided a flavor inhaler comprising the carbon heat source according to the third aspect.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a technique relating to a carbon heat source for a flavor inhaler that is excellent in ease of manufacture and has a high strength and excellent ignitability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view schematically showing a method described in a prior art document;
FIG. 2 is a view schematically showing an example of a method of the present invention;
FIG. 3 is a perspective view showing an example of a carbon heat source for a flavor inhaler;
FIG. 4 is a cross-sectional view showing an example of a flavor inhaler;
FIG. 5 is a graph showing a particle size distribution of composite particles A1;
FIG. 6 is a graph showing a particle size distribution of composite particles A2;
FIG. 7 is a graph showing a particle size distribution of composite particles A3;
FIG. 8 is a graph showing a particle size distribution of composite particles B;
FIG. 9 is a micrograph of the composite particles A2; and
FIG. 10 is a micrograph of the composite particles B.

DETAILED DESCRIPTION

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

<1. Method for Manufacturing Carbon Heat Source>

In one aspect, a method for manufacturing a carbon heat source for a flavor inhaler includes:

forming composite particles which have an average particle diameter D50 of 10-150 µm and a half-value width of 10-150 µm, with the use of, as a starting material, a slurry containing carbon particles, calcium carbonate particles, a binder and water;
molding a mixture containing the composite particles and water to give a molded article; and
drying the molded article.

The carbon heat source for a flavor inhaler is a heat source that heats a flavor source inside the flavor inhaler through combustion of the carbon heat source. The flavor source in the flavor inhaler is heated by combustion heat of the carbon heat source, but is not combusted. The flavor source generates flavor through heating. In the following description, the carbon heat source for a flavor inhaler is also simply referred to as a "carbon heat source".
FIG. 2 schematically shows an example of a method of the present invention. FIG. 2 shows:

(1) preparing a raw material slurry 1;
(2) forming composite particles 6 from the raw material slurry 1;
(3) molding the composite particles 6 to obtain a molded article 7; and
(4) drying the molded article 7 to obtain a dried molded article 8.

The dried molded article 8 may be used as a carbon heat source as it is, or may be used as a carbon heat source after being subjected to necessary processes. In FIG. 2, the raw material slurry 1 includes carbon particles la, calcium carbonate particles 1c, and an aqueous solution (dispersion medium) 1b containing a binder.
The steps of "preparing a raw material slurry", "forming composite particles", "molding", and "drying" will be described in detail below.

(Preparing a raw material slurry)

The raw material slurry contains carbon particles, calcium carbonate particles, a binder, and water.
As the carbon particles, carbon particles generally used as a raw material of a carbon heat source for a flavor inhaler can be used. Specifically, as the carbon particles, any carbon particles that can be combusted by ignition can be used. The carbon particles are preferably activated carbon particles, and more preferably activated carbon particles having a BET specific surface area of 1000 to 2500 m²/g. The carbon particles have an average particle diameter of preferably 2 to 100 µm, and more preferably 5 to 50 µm. Here, "average particle diameter" refers to an average particle diameter D50 based on a volume-based particle size distribution measured by a laser diffraction scattering-type particle size distribution measurement method.
As the carbon particles, commercially available activated carbon particles can be used, examples of which include KURARAY COAL SA2300 (average particle diameter: 6.6 µm, BET specific surface area: 2100 to 2400 m²/g, Kuraray Chemical Co., Ltd.), KURARAY COAL PW-Y (particle diameter: 45 µm or less, BET specific surface area: 1300 to 1500 m²/g, Kuraray Chemical Co., Ltd.), and KURARAY COAL SA1500 (average particle diameter: 6.19 µm, BET specific surface area: 1600 to 1800 m²/g). One kind of carbon particles may be used, or a plurality of kinds of carbon particles may be used in combination.
The carbon particles are contained in the slurry in an amount of preferably 20 to 90% by mass, and more preferably 30 to 60% by mass, with respect to a mass of a solid content contained in the slurry. As used herein, "solid content" refers to components (i.e., non-volatile components) remaining after evaporation of a liquid from the slurry. That is, "solid content" is components remaining when the slurry is made into a state of composite particles or a carbon heat source. Therefore, "solid content" includes not only components (carbon particles and calcium carbonate particles) present in a solid state in the slurry but also components (binder) dissolved in the slurry but remaining after the slurry is dried.
As the calcium carbonate particles, calcium carbonate particles generally used in combination with carbon particles as a raw material of a carbon heat source for a flavor inhaler can be used. The calcium carbonate particles can reduce the amount of combustion products, particularly the amount of carbon monoxide generated.
As the calcium carbonate particles, for example, particles having a packed bulk density of 0.3 to 1.0 g/cm³ can be used. The packed bulk density refers to a bulk density measured after filling a 100 mL vessel with particles in a level-off state (i.e., a state of loose bulk density), adding an equal amount of particles, and tapping 180 times (applying vibration). The calcium carbonate particles have an average particle diameter of preferably 100 µm or less, and more preferably 10 µm or less. It is preferable that the average particle diameter of the calcium carbonate particles be as small as possible, and the lower limit thereof is not particularly limited, but is, for example, 0.2 µm. Here, "average particle diameter" refers to an average particle diameter D50 based on a volume-based particle size distribution measured by a laser diffraction scattering-type particle size distribution measurement method.
As the calcium carbonate particles, commercially available calcium carbonate particles can be used, examples of which include Calpine F (average particle diameter: 3 µm, packed bulk density: 0.66 g/cm³, Yabashi Industries Co., Ltd.). One kind of calcium carbonate particles may be used, or a plurality of kinds may be used in combination.
The calcium carbonate particles are contained in the slurry in an amount of preferably 5 to 75% by mass, and more preferably 40 to 70% by mass, with respect to a mass of a solid content contained in the slurry.
A particle diameter ratio of the carbon particles to the calcium carbonate particles can be, for example, 10:1 to 1:10. The mass ratio of the carbon particles to the calcium carbonate particles can be, for example, 5:1 to 1:5.
As the binder, a binder generally used as a raw material of a carbon heat source for a flavor inhaler can be used. The binder serves to bind particles (carbon particles and calcium carbonate particles) in the slurry to each other to enhance a strength of a carbon heat source. The binder is dissolved in the slurry.
As the binder, a cellulose derivative, an alginate or the like may be used. Examples of the cellulose derivative include carboxymethyl cellulose, sodium carboxymethyl cellulose, methylhydroxyethyl cellulose, methyl cellulose, and hydroxypropyl cellulose.
The binder is contained in the slurry in an amount of preferably 3 to 15% by mass, and more preferably 5 to 10% by mass, with respect to a mass of the solid content contained in the slurry.
As will be described later in the section "Advantageous Effects", in the present invention, a carbon heat source is manufactured using composite particles having a small average particle diameter and a sharp particle size distribution; therefore, it is possible to manufacture a carbon heat source having a sufficient strength even when a content of a binder is reduced. Thus, in the method of the present invention, a binder content can be reduced as described above. Since the reduction in the binder content increases the content proportions of the carbon particles and the calcium carbonate particles, it is possible to enhance ignitability of the carbon heat source.
The ratio of the mass of the solid content contained in the slurry to the mass of the liquid contained in the slurry (hereinafter also referred to as a solid-liquid ratio) is preferably 1:1 to 1:9, and more preferably 1:2 to 1:4. The liquid contained in the slurry is generally water.
When the raw material slurry is spread into a sheet shape according to the method of the prior art document (see FIG. 1) described in the section "Background of the Invention", it is necessary to increase the ratio (liquid-solid ratio) of the mass of the liquid to the mass of the solid content so that the slurry can be spread into a sheet shape. On the other hand, when the composite particles are formed by directly atomizing the slurry without forming the slurry into a sheet shape, the ratio (liquid-solid ratio) of the mass of the liquid to the mass of the solid content of the slurry can be reduced. By reducing the liquid-solid ratio, it is possible to shorten a drying time for evaporating moisture thereafter, and thus it is possible to reduce manufacturing costs.

(Forming Composite Particles)

Composite particles having an average particle diameter D50 of 10 to 150 µm and a half-value width of 10 to 150 µm are formed using the raw material slurry described above. The average particle diameter D50 is preferably 10 to 120 µm.
Here, "average particle diameter D50" refers to an average particle diameter D50 based on a volume-based particle size distribution measured by a laser diffraction scattering-type particle size distribution measurement method. "Half-value width" refers to a half-value width based on a volume-based particle size distribution measured by a laser diffraction scattering-type particle size distribution measurement method. "Half-value width" refers to the full width at half maximum.
The composite particles can be formed by any method capable of forming particles having the above-described particle diameter and the above-described half-value width. Specifically, the composite particles can be formed by using a technique of directly atomizing a slurry, more specifically, using spray drying. Preferably, the composite particles can be formed by spray drying the slurry. Spray drying is a technique of atomizing a liquid or slurry into a gas and rapidly drying it to produce particles.
More preferably, the composite particles can be formed by spraying the slurry into a heated gas by an atomizer or a spray nozzle, and instantaneously drying it to form fine particles. The expression "rapidly drying" or "instantaneously drying" in the context of spray drying refers to drying being completed while the sprayed droplets are in the air (i.e., before falling to the ground). Still more preferably, the composite particles can be formed by spray drying the slurry with a rotary atomizer type spray dryer, i.e., by spraying droplets of the slurry into a heated gas by centrifugal force through rotation of a disc type atomizer (rotary atomizer) and instantaneously drying the droplets to form fine particles. The rotary atomizer type spray dryer is suitable for forming composite particles having a small particle diameter and a sharp particle size distribution.
In the case of using a rotary atomizer type spray dryer, composite particles having the above-described average particle diameter D50 and the above-described half-value width can be formed by setting the spraying conditions and drying conditions as follows, for example.

Disc diameter: 60 to 200 mm
Disc rotation speed: 8000 to 30000 rpm
Discharge rate of slurry: 15 to 160 L/h
Hot air temperature at outlet (where particles come out): 80 to 150°C

As described above, the composite particles have a small average particle diameter and a sharp particle size distribution. When such composite particles are molded, the composite particles can be molded at a uniform density throughout the entire molded article and at a high density, whereby a strength of a carbon heat source to be manufactured can be improved, and excellent ignitability can be provided.
The composite particles preferably have a spherical shape. Here, "spherical shape" refers to a shape having an average circularity of 0 to 0.2 × D [µm] (here, D refers to an average particle diameter D50 of composite particles) obtained from a micrograph of composite particles. "Average circularity" refers to an average of circularities of twenty composite particles. "Circularity" refers to a difference in radius between two circles when a microscopic image of a target particle is sandwiched by two geometric circles in a concentric manner such that an interval between the two concentric circles becomes minimum (JIS B 0621:1984).
When the composite particles are manufactured by spray drying as described above, all the composite particles can generally have a spherical shape. When composite particles all having a spherical shape are molded, the composite particles can be molded at a higher density. In the prior art document described in the section "Background of the Invention", composite particles are manufactured by spreading a raw material slurry into a sheet shape and pulverizing the obtained sheet (see FIG. 1). Thus, according to the prior art document, the composite particles do not have a spherical shape.
The composite particles preferably have a smooth surface when observed with a microscope. When the composite particles are manufactured by spray drying as described above, all the composite particles can generally have a smooth surface. When composite particles all having a smooth surface are molded, the composite particles can be molded at a higher density. In the prior art document described in the section "Background of the Invention", composite particles are manufactured by spreading a raw material slurry into a sheet shape and pulverizing the obtained sheet (see FIG. 1). Thus, according to the prior art document, the composite particles do not have a smooth surface.

(Molding)

The composite particles described above are mixed with water, and the resulting mixture is molded.
It is preferable that the amount of water mixed with the composite particles be a water amount suitable for the subsequent molding operation. The amount of water mixed with the composite particles is preferably 33 to 67% by mass, and more preferably 38 to 57% by mass, with respect to the composite particles. That is, it is preferable that the mixture be a mixture containing the composite particles and 33 to 67% by mass of water with respect to the composite particles, and it is more preferable that the mixture be a mixture containing the composite particles and 38 to 57% by mass of water with respect to the composite particles.
Water serves to dissolve the binder present on the surfaces of the composite particles to thereby bind the composite particles to each other. Therefore, it is preferable that water be uniformly present on the surfaces of the composite particles. It is preferable that the mixture be prepared by spraying water onto the surfaces of the composite particles while the composite particles are fluidized so that the water spreads over the entirety of the surfaces of the composite particles. For example, the mixture can be prepared by spraying water onto the surfaces of the composite particles while the composite particles are stirred.
When the amount of water contained in the mixture is within the range described above, it has the advantages that it is easy to mold and that the strength of the carbon heat source to be manufactured can be increased.
In the mixture, the composite particles tend to adhere to each other and may aggregate. Thus, before the mixture is molded, the aggregates of the composite particles may be disaggregated or the composite particles may be classified to select only the composite particles having a predetermined size or less.
Molding can be carried out using a molding method generally used in manufacturing of a carbon heat source for a flavor inhaler. Molding can be carried out, for example, through compression molding, extrusion molding, or punch molding. Molding can be carried out preferably through compression molding, and more preferably tablet molding. Molding can be carried out so as to obtain a molded article having a density of, for example, 0.6 to 1.0 g/cm³. A pressure during molding can be, for example, 1 to 5 kN.
It is preferable that the molded article have a shape of cylinder or polygonal prism under the assumption that the molded article will be incorporated into a cylindrical flavor inhaler.

(Drying)

By drying the molded article, a molded article dried (dried molded article) is manufactured. Drying can be carried out through heat drying. For example, the molded article can be dried at 100 to 200°C for 20 to 60 minutes. Over the drying period, the heating temperature may be constant within the above-described heating temperature range, or may vary so that the temperature rises within the above-described heating temperature range. The proportion of water in the dried molded article can be, for example, 10% by mass or less.
The dried molded article may be used as a carbon heat source as it is. Alternatively, as necessary, the dried molded article can be subjected to a chamfering process or a process of providing a groove (e.g., a cross-shaped groove) on the ignition surface. The molded article after the process may be used as a carbon heat source. The chamfering process contributes to reduction of the likelihood of causing cracking or chipping in the corner portion of the carbon heat source. The grooving process contributes to improvement of ignitability.
As described above, the dried molded article is manufactured by molding the composite particles at a uniform density throughout the entire molded article as well as at a high density, and therefore the strength is high. For this reason, the dried molded article is unlikely to crack or chip even when subjected to a process such as a chamfering process or grooving process, and is suitable for undergoing processes.

(Example of Carbon Heat Source)

An example of a carbon heat source is shown in FIG. 3. A carbon heat source 10 shown in FIG. 3 has a cylindrical shape. The carbon heat source 10 is incorporated into a flavor inhaler in such a manner that a distal end surface 11 is disposed at a distal end of the flavor inhaler.
As shown in FIG. 3, the carbon heat source 10 has a distal end surface 11, a proximal end surface 12 opposed to the distal end surface 11, a ventilation path 13 for supplying air into the flavor inhaler main body, an outer peripheral surface 14, grooves 15 provided in the distal end surface 11, a first chamfered portion 16 formed between the distal end surface 11 and the outer peripheral surface 14, and a second chamfered portion 17 formed between the proximal end surface 12 and the outer peripheral surface 14.
The ventilation path 13 is provided along the central axis C of the carbon heat source 10, and is provided so as to penetrate the carbon heat source 10. The ventilation path 13 communicates with the distal end surface 11 and the proximal end surface 12. The portion on the distal end surface 11 side of the ventilation path 13 is integral with the grooves 15. The ventilation path 13 may be provided by preparing a molded article to have a hollow cylindrical shape having a through hole, or may be provided by preparing a molded article to have a solid cylindrical shape and then forming a through hole with a drill.
The grooves 15 are formed to have an overall cross shape as viewed from the distal end surface 11 side. The shape of the grooves 15 is not limited to a cross shape. The number of grooves 15 is discretionary. In addition, the shape formed by all of the grooves 15 can be discretionary. For example, a plurality of grooves 15 may extend radially toward the outer peripheral surface 14 about the ventilation path 13. Furthermore, the grooves 15 are formed to be recessed from the distal end surface 11 and the outer peripheral surface 14 so as to extend over them. The grooves 15 are provided so as to communicate with the ventilation path 13.
The carbon heat source 10 can be formed to have the following dimensions. The total length of the carbon heat source 10 (the length of the carbon heat source 10 with respect to the central axis C direction) is appropriately set, for example, to be within a range of 5 to 30 mm, preferably within a range of 8 to 18mm. The diameter of the carbon heat source 10 (the length of the carbon heat source 10 with respect to the direction intersecting with the central axes C) is appropriately set, for example, to be within a range of 3 to 15 mm, and preferably within a range of 5 to 10 mm. The depth (length) of the grooves 15 with respect to the central axes C direction of the carbon heat source 10 is appropriately set, for example, to be within a range of 1 to 5 mm, and preferably within a range of 2 to 4 mm. The width (inner diameter) of the grooves 15 is appropriately set, for example, to be within a range of 0.5 to 2 mm. The inner diameter of the ventilation path 13 is appropriately set, for example, to be within a range of 0.5 to 4 mm.
The carbon heat source 10 may not have the ventilation path 13. In this case, it is preferable that the flavor inhaler main body (i.e., the holder) be provided with a plurality of small holes for ventilation. When the user performs inhalation with the flavor inhaler, air is supplied through the small holes to the holder and the flavor source in the holder.

(Advantageous Effects)

The above-described method does not have a problem in which molding a carbon heat source is difficult, and is excellent in ease of manufacture. According to the above-described method, a carbon heat source having a high strength and excellent ignitability can be manufactured.
In the above-described method, the composite particles used for manufacturing the carbon heat source have an average particle diameter D50 of 10 to 150 µm and a half-value width of 10 to 150 µm, having a small average particle diameter and a sharp particle size distribution. When a carbon heat source is manufactured using such composite particles, the composite particles can be molded at a uniform density throughout the entire molded article and at a high density, and this is considered to be the reason that the high strength and excellent ignitability were attained.
In addition, in the above-described method, the strength of the carbon heat source is ensured by use of the above-described composite particles, and therefore, even when the content of the binder is reduced, a carbon heat source having a sufficient strength can be manufactured. Since the reduction in the binder content increases the content proportions of the carbon particles and the calcium carbonate particles, it is possible to enhance ignitability of the carbon heat source.

<2. Composite Particles>

According to another aspect, there are provided "composite particles" described in the section <1. Method for Manufacturing Carbon Heat Source>. Specifically, there are provided composite particles containing carbon particles, calcium carbonate particles, and a binder, and having an average particle diameter D50 of 10 to 150 µm and a half-value width of 10 to 150 µm. Preferably, there are provided composite particles containing carbon particles, calcium carbonate particles, and a binder, and having an average particle diameter D50 of 10 to 120 µm and a half-value width of 10 to 150 µm.

<3. Carbon Heat Source>

According to another aspect, there is provided a carbon heat source for a flavor inhaler obtainable by the method described in the section <1. Method for Manufacturing Carbon Heat Source>. As described above, the carbon heat source has a high strength and excellent ignitability. For example, the carbon heat source can have a strength of 140 to 250 N and a density of 0.6 to 1.0 g/cm³. Preferably, the carbon heat source can have a strength of 140 to 250 N and a density of 0.7 to 0.9 g/cm³.
With a strength of 140 N or more, the carbon heat source has a sufficient strength as a carbon heat source of a flavor inhaler. The density of the carbon heat source is an index correlated with ignitability, and the lower the density, the better the ignitability. The ignitability depends not only on the density of the carbon heat source but also on other factors such as kinds of carbon particles; however, when the density of the carbon heat source is within the above-described range, for example, ignitability can be enhanced.

<4. Flavor Inhaler>

According to another aspect, there is provided a flavor inhaler including a carbon heat source for a flavor inhaler obtainable by the method described in the section <1. Method for Manufacturing Carbon Heat Source>.
FIG. 4 shows an example of a flavor inhaler that incorporates the carbon heat source shown in FIG. 3.
A flavor inhaler 20 shown in FIG. 4 includes a hollow cylindrical holder 21 extending from a mouthpiece end 21A to a distal end 21B, a carbon heat source 10 provided on the distal end 21B of the holder 21, a flavor source 22 provided downstream of the carbon heat source 10, an aluminum laminated paper 23 interposed between the holder 21 and the flavor source 22 inside the holder 21, and a filter portion 24 provided on the side of the mouthpiece end 21A inside the holder 21. In the flavor inhaler 20 shown in FIG. 4, a cavity is formed between the flavor source 22 and the filter portion 24.
Heat generated by combustion of the carbon heat source 10 can heat the flavor source 22 disposed downstream of the carbon heat source 10 to release the flavor.
The holder 21 is a paper tube formed by winding paper in a cylindrical shape. The aluminum laminated paper 23 is formed by laminating aluminum on a paper, and as compared with ordinary paper, the heat resistance and the thermal conductivity are improved. The aluminum laminated paper 23 prevents the paper pipe of the holder 21 from burning even when the carbon heat source 10 is ignited. The central axis C of the holder 21 coincides with the central axis C of the carbon heat source 10.
The flavor source 22 is provided downstream of the carbon heat source 10 at a position adjacent to the carbon heat source 10. As the flavor source 22, any flavor source capable of releasing a flavor through heating can be used. For example, the flavor source 22 can be prepared by forming a tobacco material such as leaf tobacco into a sheet, applying bellows-like pleats to this tobacco sheet to form a corrugated tobacco sheet, and gathering this corrugated tobacco sheet so as to form a plurality of air flow paths in a longitudinal direction to form a cylindrical body. As the flavor source 22, granules formed from tobacco extracts can be used, or leaf tobacco itself can be used. That is, as the flavor source 22, it is possible to adopt any tobacco filler such as general cut tobacco used for cigarettes, granular tobacco used for snuff, roll tobacco, and molded tobacco. The roll tobacco is obtained by forming sheet-shaped reconstituted tobacco into a roll shape, and has a flow path inside. The molded tobacco is obtained by molding granular tobacco with a die. Alternatively, the flavor source 22 in which a tobacco flavor or a flavor other than a tobacco flavor is carried on a carrier made of a porous material or a nonporous material may be adopted. The flavor source 22 may be incorporated into the flavor inhaler 20 after being cylindrically wound with paper, or may be incorporated into the flavor inhaler 20 after being housed in a metal or paper cup.
The filter portion 24 is composed of a filter generally used for cigarettes. The filter portion 24 can be formed of various kinds of fillers. The filter portion 24 is composed of a filler of, for example, cellulose-based semisynthetic fiber such as cellulose acetate, but the filler is not limited thereto. Examples of the filler that can be used include plant fibers such as cotton, hemp, Manila hemp, palm, and rush, animal fibers such as wool and cashmere, cellulose-based regenerated fibers such as rayon, synthetic fibers such as nylon, polyester, acrylic, polyethylene, and polypropylene, or a combination thereof. Besides the filler of cellulose acetate fiber described above, the constituent element of the filter portion 24 may be a charcoal filter containing charcoal or a filter containing particulates other than charcoal. Furthermore, the filter portion 24 may have a multi-segment structure in which two or more different types of segments are connected in the axial direction.

<5. Method According to another Aspect>

In another aspect, a method for manufacturing a carbon heat source for a flavor inhaler includes:

forming composite particles by spray drying a slurry containing carbon particles, calcium carbonate particles, a binder, and water;
molding a mixture containing the composite particles and water to give a molded article; and
drying the molded article.

The above-described method can be carried out according to the same procedures as those described in the section

<1. Method for Manufacturing Carbon Heat Source>.

When composite particles are formed by spray drying according to the above-described method, it is possible to form composite particles having a small average particle diameter and a sharp particle size distribution. Preferably, composite particles having an average particle diameter D50 of 10 to 150 µm and a half-value width of 10 to 150 µm can be formed. When such composite particles are molded, it is possible to mold composite particles at a uniform density throughout an entire molded article as well as at a high density, and this can improve a strength of a carbon heat source to be manufactured, and provide excellent ignitability.

<6. Preferred Embodiments>

The preferred embodiments of the present invention are summarized below.

[A1] A method for manufacturing a carbon heat source for a flavor inhaler, comprising:
- forming composite particles which have an average particle diameter D50 of 10-150 µm and a half-value width of 10-150 µm, with the use of, as a starting material, a slurry containing carbon particles, calcium carbonate particles, a binder, and water;
- molding a mixture containing the composite particles and water to give a molded article; and
- drying the molded article.
[A2] The method according to [A1], wherein the average particle diameter D50 is 10-120 µm, preferably 50-150 µm, more preferably 70-120 µm.
[A3] The method according to [A1] or [A2], wherein the half-value width is 30-150 µm, preferably 50-150 µm, more preferably 60-140 µm.
[A4] The method according to any one of [A1] to [A3], wherein the composite particles have a spherical shape.
[A5] The method according to any one of [A1] to [A4], wherein the forming the composite particles is performed by spray drying the slurry.
[A6] The method according to any one of [A1] to [A5], wherein the forming the composite particles is performed by spray drying the slurry using a rotary atomizer type spray drying apparatus.
[A7] The method according to any one of [A1] to [A6], wherein the binder is contained in the slurry in an amount of 3 to 15% by mass, preferably 5 to 10% by mass, with respect to a mass of a solid content contained in the slurry.
[A8] The method according to any one of [A1] to [A7], wherein the mixture is a mixture containing the composite particles and 33 to 67% by mass of water, preferably 38 to 57% by mass of water, with respect to the composite particles.
[A9] The method according to any one of [A1] to [A8], wherein a ratio (A:B) of a mass (A) of a solid content contained in the slurry to a mass (B) of a liquid contained in the slurry is 1:1 to 1:9, preferably 1:2 to 1:4.
[A10] The method according to any one of [A1] to [A9], wherein the carbon particles have an average particle diameter of 2 to 100 µm, preferably 5 to 50 µm.
[A11] The method according to any one of [A1] to [A10], wherein the carbon particles is activated carbon particles.
[A12] The method according to any one of [A1] to [A11], wherein the carbon particles are contained in the slurry in an amount of 20 to 90% by mass, preferably 30 to 60% by mass, with respect to a mass of a solid content contained in the slurry.
[A13] The method according to any one of [A1] to [A12], wherein the calcium carbonate particles have an average particle diameter of 100 µm or less (for example, 0.2 to 100 µm), preferably 10 µm or less (for example, 0.2 to 10 µm).
[A14] The method according to any one of [A1] to [A13], wherein the calcium carbonate particles are contained in the slurry in an amount of 5 to 75% by mass, preferably 40 to 70% by mass, with respect to a mass of a solid content contained in the slurry.
[A15] The method according to any one of [A1] to [A14], wherein a particle diameter ratio of the carbon particles to the calcium carbonate particles is 10:1 to 1:10.
[A16] The method according to any one of [A1] to [A15], wherein a mass ratio of the carbon particles to the calcium carbonate particles is 5:1 to 1:5.
[A17] The method according to any one of [A1] to [A16], wherein the binder is a cellulose derivative.
[A18] The method according to [A17], wherein the cellulose derivative is carboxymethyl cellulose, sodium carboxymethyl cellulose, methylhydroxyethyl cellulose, methyl cellulose, or hydroxypropyl cellulose.
[A19] The method according to [A17] or [A18], wherein the cellulose derivative is carboxymethyl cellulose.
[A20] The method according to any one of [A1] to [A19], wherein the molding is performed through compression molding.
[A21] The method according to any one of [A1] to [A20], wherein the molding is performed through tablet molding.
[A22] The method according to any one of [A1] to [A21], wherein the molding is performed so as to obtain a molded article having a density of 0.6 to 1.0 g/cm³, preferably 0.7 to 0.9 g/cm³.
[A23] The method according to any one of [A1] to [A22], wherein the molding is performed by applying a pressure of 1 to 5 kN.
[B1] A method for manufacturing a carbon heat source for a flavor inhaler, comprising:
- forming composite particles by spray drying a slurry containing carbon particles, calcium carbonate particles, a binder, and water;
- molding a mixture containing the composite particles and water to give a molded article; and
- drying the molded article.
[B2] The method according to [B1], wherein the composite particles have an average particle diameter D50 of 10 to 150 µm and a half-value width of 10 to 150 µm.
[B3] The method according to [B2], wherein the average particle diameter D50 is 10-120 µm, preferably 50-150 µm, more preferably 70-120 µm.
[B4] The method according to [B2] or [B3], wherein the half-value width is 30-150 µm, preferably 50-150 µm, more preferably 60-140 µm.
[B5] The method according to any one of [B1] to [B4], wherein the composite particles have a spherical shape.
[B6] The method according to any one of [B1] to [B5], wherein the forming the composite particles is performed by spray drying the slurry using a rotary atomizer type spray drying apparatus.
[B7] The method according to any one of [B1] to [B6], wherein the binder is contained in the slurry in an amount of 3 to 15% by mass, preferably 5 to 10% by mass, with respect to a mass of a solid content contained in the slurry.
[B8] The method according to any one of [B1] to [B7], wherein the mixture is a mixture containing the composite particles and 33 to 67% by mass of water, preferably 38 to 57% by mass of water, with respect to the composite particles.
[B9] The method according to any one of [B1] to [B8], wherein a ratio (A:B) of a mass (A) of a solid content contained in the slurry to a mass (B) of a liquid contained in the slurry is 1:1 to 1:9, preferably 1:2 to 1:4.
[B10] The method according to any one of [B1] to [B9], wherein the carbon particles have an average particle diameter of 2 to 100 µm, preferably 5 to 50 µm.
[B11] The method according to any one of [B1] to [B10], wherein the carbon particles is activated carbon particles.
[B12] The method according to any one of [B1] to [B11], wherein the carbon particles are contained in the slurry in an amount of 20 to 90% by mass, preferably 30 to 60% by mass, with respect to a mass of a solid content contained in the slurry.
[B13] The method according to any one of [B1] to [B12], wherein the calcium carbonate particles have an average particle diameter of 100 µm or less (for example, 0.2 to 100 µm), preferably 10 µm or less (for example, 0.2 to 10 µm).
[B14] The method according to any one of [B1] to [B13], wherein the calcium carbonate particles are contained in the slurry in an amount of 5 to 75% by mass, preferably 40 to 70% by mass, with respect to a mass of a solid content contained in the slurry.
[B15] The method according to any one of [B1] to [B14], wherein a particle diameter ratio of the carbon particles to the calcium carbonate particles is 10:1 to 1:10.
[B16] The method according to any one of [B1] to [B15], wherein a mass ratio of the carbon particles to the calcium carbonate particles is 5:1 to 1:5.
[B17] The method according to any one of [B1] to [B16], wherein the binder is a cellulose derivative.
[B18] The method according to [B17], wherein the cellulose derivative is carboxymethyl cellulose, sodium carboxymethyl cellulose, methylhydroxyethyl cellulose, methyl cellulose, or hydroxypropyl cellulose.
[B19] The method according to [B17] or [B18], wherein the cellulose derivative is carboxymethyl cellulose.
[B20] The method according to any one of [B1] to [B19], wherein the molding is performed through compression molding.
[B21] The method according to any one of [B1] to [B20], wherein the molding is performed through tablet molding.
[B22] The method according to any one of [B1] to [B21], wherein the molding is performed so as to obtain a molded article having a density of 0.6 to 1.0 g/cm³, preferably 0.7 to 0.9 g/cm³.
[B23] The method according to any one of [B1] to [B22], wherein the molding is performed by applying a pressure of 1 to 5 kN.
[C1] Composite particles comprising carbon particles, calcium carbonate particles, and a binder, and having an average particle diameter D50 of 10 to 150 µm and a half-value width of 10 to 150 µm.
[C2] The composite particles according to [C1], wherein the average particle diameter D50 is 10-120 µm, preferably 50-150 µm, more preferably 70-120 µm.
[C3] The composite particles according to [C1] or [C2], wherein the half-value width is 30-150 µm, preferably 50-150 µm, more preferably 60-140 µm.
[C4] The composite particles according to any one of [C1] to [C3], wherein the composite particles have a spherical shape.
[C5] The composite particles according to any one of [C1] to [C4], wherein the binder is contained in the composite particles in an amount of 3 to 15% by mass, preferably 5 to 10% by mass.
[C6] The composite particles according to any one of [C1] to [C5], wherein the carbon particles have an average particle diameter of 2 to 100 µm, preferably 5 to 50 µm.
[C7] The composite particles according to any one of [C1] to [C6], wherein the carbon particles is activated carbon particles.
[C8] The composite particles according to any one of [C1] to [C7], wherein the carbon particles are contained in the composite particles in an amount of 20 to 90% by mass, preferably 30 to 60% by mass.
[C9] The composite particles according to any one of [C1] to [C8], wherein the calcium carbonate particles have an average particle diameter of 100 µm or less (for example, 0.2 to 100 µm), preferably 10 µm or less (for example, 0.2 to 10 µm).
[C10] The composite particles according to any one of [C1] to [C9], wherein the calcium carbonate particles are contained in the composite particles in an amount of 5 to 75% by mass, preferably 40 to 70% by mass.
[C11] The composite particles according to any one of [C1] to [C10], wherein a particle diameter ratio of the carbon particles to the calcium carbonate particles is 10:1 to 1:10.
[C12] The composite particles according to any one of [C1] to [C11], wherein a mass ratio of the carbon particles to the calcium carbonate particles is 5:1 to 1:5.
[C13] The composite particles according to any one of [C1] to [C12], wherein the binder is a cellulose derivative.
[C14] The composite particles according to [C13], wherein the cellulose derivative is carboxymethyl cellulose, sodium carboxymethyl cellulose, methylhydroxyethyl cellulose, methyl cellulose, or hydroxypropyl cellulose.
[C15] The composite particles according to [C13] or [C14], wherein the cellulose derivative is carboxymethyl cellulose.
[D1] A carbon heat source for a flavor inhaler obtainable by the method according to any one of [A1] to [A23].
[D2] A carbon heat source for a flavor inhaler obtainable by the method according to any one of [B1] to [B23].
[D3] The carbon heat source for the flavor inhaler according to [D1] or [D2], wherein the carbon heat source has a strength of 140 to 250 N and a density of 0.6 to 1.0 g/cm³.
[D4] The carbon heat source for the flavor inhaler according to any one of [D1] to [D3], wherein the carbon heat source has a strength of 140 to 250 N and a density of 0.7 to 0.9 g/cm³.
[E1] A flavor inhaler comprising the carbon heat source according to any one of [D1] to [D4].
[E2] A flavor inhaler comprising: a hollow cylindrical holder extending from a mouthpiece end to a distal end; the carbon heat source according to any one of [D1] to [D4] provided on the distal end; and a flavor source provided downstream of the carbon heat source inside the holder.
[E3] The flavor inhaler according to [E2], further comprising a filter portion provided on the side of the mouthpiece end inside the holder.
[E4] The flavor inhaler according to [E2] or [E3], further comprising an aluminum laminated paper interposed between the holder and the flavor source.

EXAMPLES

[Test Example 1] Composite Particles

1-1. Preparation of Composite Particles

(1) Preparation of Slurry A1

As carbon particles, activated carbon particles were used; specifically, the mixture of KURARAY COAL SA2300 (average particle diameter: 6.6 µm, BET specific surface area: 2100 to 2400 m²/g, Kuraray Chemical Co., Ltd.) and KURARAY COAL PW-Y (particle diameter: 45 µm or less, BET specific surface area: 1300 to 1500 m²/g, Kuraray Chemical Co., Ltd.) (mass ratio of 2:8) was used. As calcium carbonate particles, Calpine F (average particle diameter: 3 µm, packed bulk density: 0.66 g/cm³, Yabashi Industries Co., Ltd.) was used. As a binder, carboxymethyl cellulose was used; specifically, SUNROSE F10LC (Nippon Paper Industries Co., Ltd.) was used.
A slurry A1 was prepared by mixing, with a laboratory mixer, a solid content composed of 43% by mass of carbon particles, 49.5% by mass of calcium carbonate particles, and 7.5% by mass of a binder, with water, at a solid-liquid ratio (mass ratio) of 1:3.5.

(2) Spray Drying

The slurry A1 was spray dried to prepare composite particles. Spray drying was carried out using a rotary atomizer type spray drying apparatus (RDL-050CM). Specifically, the raw material slurry was fed to a rapidly rotating disc, and the droplets were scattered in the heated gas through the centrifugal force to atomize. Thereby, composite particles A1 (average particle diameter (D50) 76 µm) were prepared. The conditions of spray drying were as follows.

Disc diameter: 60 mm
Disc rotation speed: 8000 to 13000 rpm
Discharge rate of slurry: 15 to 30 L/hour
Hot air temperature at outlet (where particles come out): 80 to 120°C

(1) Preparation of Slurry A2

A slurry A2 was prepared according to the same procedure as in preparation of the slurry A1, except that the solid content composed of carbon particles, calcium carbonate particles and a binder was mixed with water at a solid-liquid ratio (mass ratio) of 1:3.

(2) Spray Drying

The slurry A2 was spray dried to prepare composite particles. Spray drying was carried out using a rotary atomizer type spray drying apparatus (SD-6.3R type, GEA Process Engineering Co., Ltd. (former Niro Japan Co., Ltd.)). Specifically, the raw material slurry was fed to a rapidly rotating disc, and the droplets were scattered in the heated gas through the centrifugal force to atomize. Thereby, composite particles A2 (average particle diameter (D50) 94 µm) were prepared. The conditions of spray drying were as follows.

Disc diameter: 100 mm
Disc rotation speed: 10000 to 30000 rpm
Discharge rate of slurry: 20 to 40 L/hour
Hot air temperature at outlet (where particles come out): 100 to 150°C

The slurry A3 was spray dried to prepare composite particles. Spray drying was carried out using a rotary atomizer type spray drying apparatus (SDR-27, IS Japan Co., Ltd.). Specifically, the raw material slurry was fed to a rapidly rotating disc, and the droplets were scattered in the heated gas through the centrifugal force to atomize. Thereby, composite particles A3 (average particle diameter (D50) 110 µm) were prepared. The conditions of spray drying were as follows.

Disc diameter: 150 mm
Disc rotation speed: 15000 to 25000 rpm
Discharge rate of slurry: 70 to 160 L/hour
Hot air temperature at outlet (where particles come out): 100 to 140°C

(1) Preparation of Slurry B

A slurry B was prepared according to the same procedure as in preparation of the slurry A1, except that the solid content composed of carbon particles, calcium carbonate particles, and a binder was mixed with water at a solid-liquid ratio (mass ratio) of 1:4.75.

(2) Forming into a Sheet

The slurry B was formed into a sheet. The sheet was formed using a compact disc (CD) dryer (manufactured by Nishimura Works Co., Ltd.). Specifically, the following procedure was carried out.
In the CD dryer, the gap between the scraper and the disc was adjusted to 0.2 mm. The disc was heated to 140°C, and rotated at 0.8 rpm. The slurry was fed to a circulation tank, and the slurry in the circulation tank was sprayed onto the disc using the pump. The dried product (in a sheet form) dried on the disc was collected with the scraper.

(3) Pulverization and Classification

The obtained dried product (in a sheet form) was pulverized and classified. Pulverization was carried out using a tabletop mill (Wonder Blender), and classification was carried out using the sieve. Specifically, the following procedure was carried out.
The dried product was sieved to classify it into a raw material of 100 µm or more and 300 µm or less. The raw material exceeding 300 µm was fed to a pulverizing apparatus to be pulverized. The operations of classification and pulverization were repeated to obtain pulverized products having a target particle diameter of 100 to 300 µm. The obtained pulverized products are referred to as composite particles B.

1-2. Evaluation Method

(1) Measurement of Particle Size Distribution

The particle size distributions of the composite particles A1, the composite particles A2, the composite particles A3 and the composite particles B were measured. The particle size distribution was measured using the laser diffraction scattering-type particle size distribution measuring device LMS-2000e (Seishin Enterprise Co., Ltd.).
The measurement method and the measurement conditions were as follows.
Measurement method:

1. A blank measurement was carried out with only compressed air.
2. An appropriate amount of a sample was placed in a drying unit.

Measurement conditions:

Measurement range 0.20 to 20000.00 µm

Compressed air pressure 0.1 MPa

Measurement method Injection type dry measurement
The particle size distributions of the composite particles A1, the composite particles A2, and the composite particles A3 are shown in FIGS. 5 to 7, respectively, and the particle size distribution of the composite particles B is shown in FIG. 8.

(2) Microscopic Observation

The composite particles A1, the composite particles A2, the composite particles A3, and the composite particles B were observed with an optical microscope. FIG. 9 shows a micrograph of the composite particles A2, and FIG. 10 shows a micrograph of the composite particles B.

1-3. Evaluation Results

The following findings were obtained from the measurement results of the particle size distribution. The composite particles A1 had an average particle diameter D50 of 76 µm and a half-value width of 62 µm (see FIG. 5). The composite particles A2 had an average particle diameter D50 of 94 µm and a half-value width of 103 µm (see FIG. 6). The composite particles A3 had an average particle diameter D50 of 110 µm and a half-value width of 137 µm (see FIG. 7). The composite particles B had an average particle diameter D50 of 221 µm and a half-value width of 258 µm (see FIG. 8).
The following findings were obtained from the microscopic observation: The composite particles A1, the composite particles A2, and the composite particles A3 had a spherical shape, and smooth particle surfaces (see FIG. 9). The average circularity of the composite particles A2 was 11.5 µm (0.12 × D50). On the other hand, because the composite particles B were pulverized products, they did not have a spherical shape and did not have smooth surfaces (see FIG. 10). The average circularity of the composite particles B was 66.7 µm (0.30 × D50).

[Test Example 2] Carbon Heat Source

Carbon heat sources were manufactured using the composite particles prepared in Test Example 1. A carbon heat source A1 was manufactured from the composite particles A1, a carbon heat source A2 was manufactured from the composite particles A2, a carbon heat source A3 was manufactured from the composite particles A3, and a carbon heat source B1 and a carbon heat source B2 were manufactured from the composite particles B.

Table 1 collectively shows the manufacturing conditions of the carbon heat source A1, the carbon heat source A2, the carbon heat source A3, the carbon heat source B1, and the carbon heat source B2.

[Table 1]

	Composition of solid content in slurry			Formation of composite particles			Molding
	Carbon particles	Calcium carbonate particles	Binder	Solid-liquid ratio of slurry	Method of preparing composite particles	Average particle diameter D50 of composite particles	Water content at the time of molding
Carbon Heat Source A1	43%	49.5%	7.5%	1:3.5	Spray drying slurry	76 µm	30%
Carbon Heat Source A2	43%	49.5%	7.5%	1:3	Spray drying slurry	94 µm	30%
Carbon Heat Source A3	43%	49.5%	7.5%	1:3.5	Spray drying slurry	110 µm	30%
Carbon Heat Source B1 (Comparative Example 1)	43%	49.5%	7.5%	1:4.75	Forming slurry into sheet and pulverizing sheet	220 µm	34%
Carbon Heat Source B2 (Comparative Example 2)	43%	49.5%	7.5%	1:4.75	Forming slurry into sheet and pulverizing sheet	220 µm	30%

2-1. <Manufacture of Carbon Heat Source

(1) Adding Water

Water was added to the composite particles A1 prepared in Test Example 1. 30 parts by mass of water was added to 70 parts by mass of the composite particles A1. That is, water was added in an amount of 43% by mass based on the composite particles A1. Water was added to the composite particles A1 with a washing bottle, and the obtained mixture was mixed using a Kenmix mixer. The composite particles aggregated, and thus disaggregation of the aggregates was carried out. The disaggregation was carried out using a tabletop mill (Wonder Blender). Thereby, a mixture (base material) of a mixture A1 and water was prepared. In Table 1, "water content" represents the proportion (mass%) of water in the mixture.

(2) Classifying

The mixture (base material) of the composite particles A1 and water was classified into a mixture of 500 µm or less using the sieve.

(3) Molding

The classified base material was tablet-molded. The tablet molding was carried out using a tablet molding machine CREC (manufactured by Kikusui Seisakusho Ltd.). The base material was molded into a cylindrical shape. Specifically, the following procedure was carried out. The classified base material was fed to a quantitative feeder. The stirring feed shoe was rotated at 80 rpm, and the base material was fed from the quantitative feeder to the stirring feed shoe. With the amount of the base material in the stirring feed shoe being kept constant, the rotary table of the tablet molding machine was rotated at 15 rpm to carry out tablet molding. The tableting pressure was 1.5 to 3.0 kN.

(4) Drying

The resulting tablet product was dried. Drying was carried out using the constant temperature drier OF-300S (manufactured by ASONE). Specifically, the tablet product was dried at 100°C for 8.6 minutes, and then dried at 200°C for 17.3 minutes.

(5) Cutting

In the tablet product after drying, a through hole was formed with a drill to provide a ventilation path 13 as shown in FIG. 3. The dried tablet product was subjected to the chamfering processing and the cross-shaped groove processing using the cutting device MTC (device name: carbon molded product processing test machine, company name: Yamamoto Kikai Seisakusho K.K.). As shown in FIG. 3, chamfering was applied to both the distal end surface 11 and the proximal end surface 12, and cross-shaped grooving was applied only to the distal end surface 11. After the processing, the ventilation path 13 was air-blown, and the groove portion 15 formed by the crossing processing was air-blown. Thereby, a carbon heat source A1 was manufactured.
The manufactured carbon heat source A1 had a shape shown in FIG. 3 and the following dimensions.

Total length (length of carbon heat source in central axial C direction): 13 mm
Diameter (length of carbon heat source in direction intersecting central axis C): 6.49 mm
Depth (length) of groove 15 in central axis C direction: 3.0 mm
Width (inner diameter) of groove 15: 0.6 mm
Inner diameter of ventilation path 13: 1.0 mm

A carbon heat source A2 was manufactured according to the same procedure as in the manufacture of the carbon heat source A1, except that the composite particles A2 were used instead of the composite particles A1.

A carbon heat source A3 was manufactured according to the same procedure as in the manufacture of the carbon heat source A1, except that the composite particles A3 were used instead of the composite particles A1.

A carbon heat source B1 was manufactured according to the same procedure as in the manufacture of the carbon heat source A1, except that the composite particles B were used instead of the composite particles A1, and that water was added in the amount of 34% by mass based on the composite particles B.

A carbon heat source B2 was manufactured according to the same procedure as in the manufacture of the carbon heat source A1, except that the composite particles B were used instead of the composite particles A1.

2-2. Evaluation Method

(1) Strength

The strength of the carbon heat source was determined by measuring the breaking strength as follows.

Measuring device: SHIMAZU EZ-S 500N
Load cell maximum pressurization amount: 500 N
Compression speed: 10 mm/min
Compression element: Attachment having a V-shaped distal end portion

In the carbon heat source, the center of the side portion was pressed until it was broken with the attachment being positioned to be perpendicular to the carbon heat source, and the pressure at the time of breaking (breaking strength) was measured. The strength was evaluated based on the values of breaking strength as follows.

○: Breaking strength 140 [N] or more
△: Breaking strength 80 [N] or more and less than 140 [N]
×: Breaking strength less than 80 [N]

(2) Ignitability

The ignitability of the carbon heat source was evaluated using a borgwaldt electrothermal lighter with a new filament.
The filament of the lighter was attached directly to the carbon heat source. The cross of the filament of the lighter and the cross of the groove of the carbon heat source were directly attached so as to overlap each other. The output of the lighter was set to "strong". Evaluation was made by changing the time from when the switch of the lighter was turned on to when inhalation started. The amount of inhalation was 55 mL/2sec. At the end of inhalation, the lighter was removed from the carbon heat source. When the carbon heat source was red-hot at the second puff (15 seconds later), it was determined that the ignition occurred.
The surface (distal end surface) of the carbon heat source disposed on the upper punch side of the tablet molding machine was evaluated. The distal end surface of the carbon heat source is divided into four regions (islands) by the cross-shaped groove processing (see FIG. 3). The ignitability was evaluated based on the number of ignited islands.

○: When four islands were ignited
△: When two or three islands were ignited
×: When one island was ignited or no ignition occurred

(3) Density

The volume of the carbon heat source having a cylindrical shape was calculated from the diameter of the cylinder and the height of the cylinder. In addition, the mass of the carbon heat source was measured. The density [g/cm³] of the carbon heat sources was calculated from the values of the volume and the mass. The density of the carbon heat source is an index correlated with ignitability, and the lower the density, the better the ignitability.

2-3. Evaluation Results

The evaluation results are shown in Table 2.

[Table 2]

	Breaking strength [N]	Evaluation of strength	Evaluation of ignitability	Density [g/cm³]
Carbon Heat Source A1	180	O	○	0.89
Carbon Heat Source A2	170	O	O	0.90
Carbon Heat Source A3	170	O	O	0.90
Carbon Heat Source B1 (Comparative Example 1)	170	O	O	0.90
Carbon Heat Source B2 (Comparative Example 2)	110	△	O	0.89

The manufacture of the carbon heat source A1, the carbon heat source A2, and the carbon heat source A3 did not have a problem in which molding of carbon heat sources was difficult, and they were excellent in ease of manufacture. The carbon heat source A1, the carbon heat source A2, and the carbon heat source A3 had high strengths and excellent ignitability. All of the composite particles A1, the composite particles A2, and the composite particles A3 that were used to manufacture the carbon heat source A1, the carbon heat source A2, and the carbon heat source A3 had small average particle diameters and sharp particle size distributions. Thus, the composite particles could be molded at a uniform density throughout the entire molded article and at a high density, and because of this, it is considered that the strengths of the manufactured carbon heat sources could be improved and excellent ignitability could be provided.
On the other hand, when the carbon heat source was manufactured using the composite particles B, molding was difficult. In view of this, the carbon heat source B1 was manufactured by increasing the amount of water added at the time of molding; as a result, the molding material (base material) easily adhered to the tablet molding machine. In particular, when continuous production was performed by the tablet molding machine, while the carbon heat source could be manufactured in the initial stage, the base material gradually adhered to the inside of the chamber or the compression unit of the tablet molding machine, and continuous production became impossible. The manufactured carbon heat source B1 had a high strength and excellent ignitability, but had a problem in which continuous production was not possible.
When the carbon heat source B2 was manufactured using the composite particles B by adding water in an amount generally used at the time of molding (i.e., 30% by mass of water with respect to the composite particles B), molding was difficult. The obtained carbon heat source B2 had no problem in ignitability, but the strength was not sufficient.
The composite particles B had a larger average particle diameter and a larger half-value width, as compared to the composite particles A1, the composite particles A2, and the composite particles A3. For this reason, the composite particles B could not be molded at a uniform density throughout the entire molded article and at a high density, and it is considered that this caused the problems such as the difficulty in molding and the low strength of the manufactured carbon heat source. In addition, because the composite particles B were pulverized products, they did not have a spherical shape and had an uneven and non-smooth surface. It is considered that the shape of the composite particles B also affected the difficulty in molding and the decrease in the strength of the carbon heat source.

Claims

A method for manufacturing a carbon heat source for a flavor inhaler, comprising:
forming composite particles which have an average particle diameter D50 of 10-150 µm and a half-value width of 10-150 µm, with the use of, as a starting material, a slurry containing carbon particles, calcium carbonate particles, a binder, and water;

molding a mixture containing the composite particles and water to give a molded article; and

drying the molded article.
The method according to claim 1, wherein the composite particles have a spherical shape.
The method according to claim 1 or 2, wherein the forming the composite particles is performed by spray drying the slurry.
The method according to any one of claims 1 to 3, wherein the binder is contained in the slurry in an amount of 3 to 15% by mass with respect to a mass of a solid content contained in the slurry.
The method according to any one of claims 1 to 4, wherein the mixture is a mixture containing the composite particles and 33 to 67% by mass of water with respect to the composite particles.
The method according to any one of claims 1 to 5, wherein a ratio (A:B) of a mass (A) of a solid content contained in the slurry to a mass (B) of a liquid contained in the slurry is 1:1 to 1:9.
The method according to any one of claims 1 to 6, wherein the carbon particles have an average particle diameter of 2 to 100 µm.
The method according to any one of claims 1 to 7, wherein the carbon particles are contained in the slurry in an amount of 20 to 90% by mass with respect to a mass of a solid content contained in the slurry.
The method according to any one of claims 1 to 8, wherein the calcium carbonate particles have an average particle diameter of 100 µm or less.
The method according to any one of claims 1 to 9, wherein the calcium carbonate particles are contained in the slurry in an amount of 5 to 75% by mass with respect to a mass of a solid content contained in the slurry.
The method according to any one of claims 1 to 10, wherein the binder is a cellulose derivative.
The method according to any one of claims 1 to 11, wherein the molding is performed through compression molding.
Composite particles comprising carbon particles, calcium carbonate particles, and a binder, and having an average particle diameter D50 of 10 to 150 µm and a half-value width of 10 to 150 µm.
A carbon heat source for a flavor inhaler obtainable by the method according to any one of claims 1 to 12.
The carbon heat source for the flavor inhaler according to claim 14, wherein the carbon heat source has a strength of 140 to 250 N and a density of 0.6 to 1.0 g/cm³.
A flavor inhaler comprising the carbon heat source according to claim 14 or 15.