JP2023065055A - solid fuel - Google Patents

Abstract

To provide a solid fuel excellent in storage stability and suitably usable as the solid fuel.SOLUTION: A solid fuel comprises: at least one monohydric alcohol (A) selected from a group consisting of methanol, ethanol, and propanol; at least one polyhydric alcohol selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, and glycerin, and/or water (B); and a fatty acid salt (C) having 12 to 22 carbon atoms, wherein content of the monohydric alcohol (A) is 50 to 90 mass%, and the content of the fatty acid salt (C) is 3 to 20 mass%.SELECTED DRAWING: None

Description

The present invention relates to solid fuels.

2. Description of the Related Art As a fuel for heating cooked dishes, there is known a solid fuel in which a cylindrical or prismatic solid fuel body sealed with a resin film is wrapped in an exterior material.

For example, Patent Literature 1 discloses that volatilization of fuel components can be suppressed by covering the surface of solid fuel with polyethylene. Further, Patent Document 2 discloses that the volatilization of the fuel component can be suppressed and the storage stability can be improved by blending a fatty acid ester of a polyhydric alcohol without covering the surface of the solid fuel.

JP-A-1-267133 JP-A-8-231970

As a result of intensive studies by the present inventors, the method of covering the surface of the solid fuel with a protective layer such as polyethylene may cause scratches or peeling of the protective layer during storage, etc., and it was found that storage stability could not be improved. It turned out that there was room. In addition, it was found that there is room for improvement in the storage stability of the method of blending fatty acid esters of polyhydric alcohols without covering the surface of the solid fuel.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a solid fuel that is excellent in storage stability and that can be suitably used as a solid fuel.

In order to achieve the above object, the solid fuel of the present invention comprises at least one monohydric alcohol (A) selected from the group consisting of methanol, ethanol, and propanol, ethylene glycol, diethylene glycol, propylene glycol, and glycerin. At least one polyhydric alcohol and / or water (B) selected from the group consisting of and a fatty acid salt (C) having 12 to 22 carbon atoms, and the content of the monohydric alcohol (A) is 50 to 90% by mass, and the content of the fatty acid salt (C) is 3 to 20% by mass.
The solid fuel of the present invention has excellent storage stability and can be suitably used as a solid fuel. Although the reason why such an effect is obtained in the present invention is not clear, it is presumed as follows.
When the content of the monohydric alcohol (A) is reduced to the above specific amount, usually, the necessary fire force as a solid fuel cannot be obtained, or good solidification property cannot be obtained, and the solid fuel liquefies during combustion. It can spread to an unintended range and cannot be solidified in the first place. However, by blending the polyhydric alcohol and / or water (B) while reducing the content of the monohydric alcohol (A), the storage stability is excellent, and the fire force required as a solid fuel is good. A good solidification property is also obtained. Furthermore, by including a specific amount of the monohydric alcohol (A), the polyhydric alcohol and / or water (B), and a specific amount of the fatty acid salt (C), the content of the monohydric alcohol (A) Even if the amount is small, it can be suitably used as a fuel in a solid state.
In addition, in the present invention, compared to the method of blending a fatty acid ester of a polyhydric alcohol, the storage stability can be improved by more effectively suppressing volatilization of the fuel, and at the same time, the ignitability and solidification properties as a solid fuel can be improved. performance can be maintained.
In addition, in this specification, solid means showing the property of a solid, and is a concept also including a gel state.

The solid fuel of the present invention preferably has a polyhydric alcohol content of 1 to 40% by mass.
Thereby, the effect of the present invention becomes more remarkable.

The solid fuel of the present invention preferably has a water content of 1 to 40% by mass.
Thereby, the effect of the present invention becomes more remarkable.

The solid fuel of the present invention preferably contains a thickening agent, and more preferably the thickening agent contains a polysaccharide.
As a result, scattering of powdery particles during combustion can also be suppressed.

The solid fuel of the present invention preferably has a surface covered with paraffin, and more preferably, the paraffin has a thickness of 0.1 to 2.0 mm.
As a result, volatilization of fuel components is more effectively prevented, and the effects of the present invention become more pronounced. In addition, the solid fuel is prevented from being ignited unintentionally while maintaining the ignitability necessary for the fuel, thus providing a safer solid fuel.

In the solid fuel of the present invention, the fatty acid salt (C) is preferably a fatty acid salt having 16 to 20 carbon atoms.
As a result, the fuel can be more preferably in a solid state, and the effects of the present invention become more remarkable.

In the solid fuel of the present invention, the monohydric alcohol (A) is methanol,
the polyhydric alcohol and/or water (B) are ethylene glycol and/or diethylene glycol and water;
The fatty acid salt (C) is a stearate,
Further, it preferably contains methyl cellulose.
As a result, the effect of the present invention becomes more pronounced, and the solidifying property, the force of fire, the smell during combustion, and the shape during combustion are particularly excellent.

The solid fuel of the present invention has excellent storage stability and can be suitably used as a solid fuel.

The solid fuel of the present invention includes at least one monohydric alcohol (A) selected from the group consisting of methanol, ethanol, and propanol, and at least selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, and glycerin. One type of polyhydric alcohol and / or water (B) and a fatty acid salt (C) having 12 to 22 carbon atoms, the content of the monohydric alcohol (A) is 50 to 90% by mass, The content of the fatty acid salt (C) is 3 to 20% by mass.
Each component will be described below.

(Monohydric alcohol (A))
Monohydric alcohol (A) is at least one alcohol selected from the group consisting of methanol, ethanol, and propanol. The monohydric alcohol (A) is a component that functions as a combustible component, and as the content increases, the ignitability, fire force, and shape stability improve. descend.
The monohydric alcohol (A) may be used alone or in combination of two or more.

The monohydric alcohol (A) is preferably at least one alcohol selected from the group consisting of methanol and ethanol for the reasons of shape stability during combustion and odor suppression, and is preferably methanol. more preferred.

The content of the monohydric alcohol (A) is 50-90% by mass in 100% by mass of the solid fuel. If it is less than 50% by mass, sufficient fire force and ignitability cannot be obtained, and if it exceeds 90% by mass, sufficient storage stability cannot be obtained. The content of the monohydric alcohol (A) is preferably 55% by mass or more, more preferably 60% by mass or more, still more preferably 65% by mass or more, particularly preferably 68% by mass or more, and preferably 85% by mass or less. , more preferably 80% by mass or less, still more preferably 75% by mass or less, particularly preferably 73% by mass or less, and most preferably less than 70% by mass.
Here, content of monohydric alcohol (A) means total content, when containing 2 or more types of monohydric alcohols (A). The same applies to the contents of other components.

(Polyhydric alcohol and/or water (B))
Polyhydric alcohol and/or water (B) is at least one polyhydric alcohol and/or water selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, and glycerin. By blending the polyhydric alcohol and/or water (B) together with the monohydric alcohol (A), it is possible to obtain excellent storage stability and an appropriate fire force required as a solid fuel.
The polyhydric alcohol and/or water (B) may be used alone or in combination of two or more.

As the polyhydric alcohol and/or water (B), a polyhydric alcohol is preferable because it is excellent in fire force, preservability, and ignitability, and good solidification property can be obtained, and moderate combustibility can also be obtained. Therefore, it is more preferable to use a polyhydric alcohol and water together.

The polyhydric alcohol is preferably at least one alcohol selected from the group consisting of ethylene glycol and diethylene glycol for reasons of ignitability and continuity of combustion, and for the reason that the odor during combustion can be reduced. , more preferably ethylene glycol.

The content of the polyhydric alcohol and/or water (B) is preferably 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more, and particularly preferably 10% by mass in 100% by mass of the solid fuel. % or more, most preferably 15 mass % or more, preferably 40 mass % or less, more preferably 35 mass % or less, still more preferably 30 mass % or less, particularly preferably 25 mass % or less. If it is less than 1% by mass, there is a tendency that sufficient storage stability cannot be obtained, and if it exceeds 40% by mass, there is a tendency that sufficient fire force, ignitability, and combustion continuity cannot be obtained.

The content of the polyhydric alcohol is preferably 1% by mass or more, more preferably 2% by mass or more, still more preferably 5% by mass or more, and particularly preferably 8% by mass or more, based on 100% by mass of the solid fuel. It is 40% by mass or less, more preferably 35% by mass or less, still more preferably 30% by mass or less, particularly preferably 25% by mass or less, most preferably 20% by mass or less, and most preferably 15% by mass or less. If it is less than 1% by mass, there is a tendency that sufficient storage stability cannot be obtained, and if it exceeds 40% by mass, there is a tendency that sufficient fire force, ignitability, and combustion continuity cannot be obtained.

The content of water is preferably 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more, particularly preferably 8% by mass or more, and preferably 40% by mass in 100% by mass of solid fuel. % or less, more preferably 35 mass % or less, more preferably 30 mass % or less, particularly preferably 25 mass % or less, most preferably 20 mass % or less, and most preferably 15 mass % or less. If it is less than 1% by mass, there is a tendency that sufficient storage stability cannot be obtained, and if it exceeds 40% by mass, there is a tendency that sufficient fire force and ignitability cannot be obtained, and sufficient solidification properties cannot be obtained. There is

(Fatty acid salt (C))
Fatty acid salt (C) is a fatty acid salt having 12 to 22 carbon atoms.
The fatty acid salt (C) is, for example, a salt formed by a neutralization reaction between a fatty acid and an alkali, and exhibits sufficient solidification properties by converting the fatty acid into a fatty acid salt through a neutralization reaction with an alkali.
The fatty acid salt (C) may be used alone or in combination of two or more.

The fatty acid salt has 12-22 carbon atoms, preferably 16-20 carbon atoms.

The fatty acid of the fatty acid salt (C) is not particularly limited, but for example, saturated fatty acids such as lauric acid, myristic acid, stearic acid, palmitic acid, behenic acid, pentadecyl acid, margaric acid, arachidic acid; palmitoleic acid, oleic acid , unsaturated fatty acids such as linoleic acid, linolenic acid, and arachidonic acid; These may be used alone or in combination of two or more. Among them, saturated fatty acids are preferable for the reason of solidification stability, and at least one selected from the group consisting of lauric acid, myristic acid, stearic acid, palmitic acid, and behenic acid is more preferable, and stearic acid and palmitic acid. Acids are more preferred, and stearic acid is particularly preferred.

Salts of the fatty acid salt (C) are not particularly limited, but examples thereof include sodium salts, potassium salts and the like. These may be used alone or in combination of two or more. Among them, the sodium salt is preferred for the reason of solidification stability.

The content of fatty acid salt (C) is 3 to 20% by mass in 100% by mass of solid fuel. If the content of the fatty acid salt (C) exceeds 20% by mass or is less than 3% by mass, sufficient solidification properties cannot be obtained, and the shape during combustion is also poor. The content of the fatty acid salt (C) is preferably 4% by mass or more, more preferably 5% by mass or more, still more preferably 6% by mass or more, particularly preferably 8% by mass or more, and preferably 18% by mass or less, It is more preferably 16% by mass or less, still more preferably 14% by mass or less, and particularly preferably 12% by mass or less.

The solid fuel preferably contains a thickening agent. As a result, it is possible to suppress the scattering of particles during combustion, and there is a tendency that the stability of solidification can be further improved.
A thickener may be used independently and may use 2 or more types together.

Examples of thickeners include, but are not limited to, polysaccharides, polyacrylamides, polyalkylene oxides, polyacrylic acid and salts thereof, and polyvinyl alcohol. Among these, polysaccharides are preferred because they suppress scattering of fuel particles during combustion. That is, it is preferable that the thickener contains a polysaccharide.

Examples of polysaccharides include, but are not limited to, cellulose derivatives, starch, alginic acid and its salts (eg, sodium alginate), guar gum, gellan gum, gelatin, pectin, xanthan gum, carrageenan, and the like. Among these, cellulose derivatives are preferable because they suppress scattering of fuel particles during combustion. That is, it is preferable that the thickener contains a cellulose derivative.

Examples of cellulose derivatives include, but are not limited to, cellulose ethers such as methylcellulose, carboxymethylcellulose, carboxyethylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, and hydroxypropylmethylcellulose. Among them, cellulose ether is preferable, at least one selected from the group consisting of methylcellulose and hydroxypropylmethylcellulose is more preferable, and methylcellulose is even more preferable, because it suppresses scattering of fuel during combustion. That is, it is preferable that the thickener contains methylcellulose.

The viscosity of a 2% by mass aqueous solution of the thickener at 20° C. is preferably 100 mPa s or more and 100,000 mPa s or less, more preferably 150 mPa s or more and 50,000 mPa s or less, still more preferably 200 mPa s or more. 000 mPa·s or less.
As used herein, the viscosity of a 2% by mass aqueous solution of a thickener at 20° C. is measured by a Brookfield rotational viscometer in accordance with JISZ8803 (2011).

The content of the thickener is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and still more preferably 0.1% by mass or more, based on 100% by mass of the solid fuel. It is 0% by mass or less, more preferably 0.8% by mass or less, and still more preferably 0.5% by mass or less.

In addition to the above components, the solid fuel may contain additives commonly used in solid fuels. Additives include, for example, fragrances, color powders, stabilizers, and the like. Each of these additives may be used alone or in combination of two or more.

In the solid fuel, the monohydric alcohol (A) is methanol,
the polyhydric alcohol and/or water (B) are ethylene glycol and/or diethylene glycol and water;
The fatty acid salt (C) is a stearate,
Furthermore, it preferably contains methyl cellulose,
In the solid fuel, the monohydric alcohol (A) is methanol,
The polyhydric alcohol and / or water (B) is ethylene glycol and water,
The fatty acid salt (C) is a stearate,
Furthermore, it is more preferable to contain methyl cellulose.
As a result, the effect of the present invention becomes more pronounced, and the solidifying property, the force of fire, the smell during combustion, and the shape during combustion are particularly excellent.

The solid fuel is manufactured by a general method. That is, it can be produced by a method of mixing and neutralizing the respective components while heating in a mixing tank, and then cooling and solidifying.
The solid fuel is a solid containing alcohol as a main component. In order to solidify alcohol, which is normally liquid, a solid fuel composition contains a fatty acid and an alkali, and the fatty acid is neutralized with the alkali to form a fatty acid salt, thereby obtaining sufficient solidification properties. , the solid fuel composition can be a solid fuel that is a solid. Note that the lumped solid fuel may be formed into a predetermined shape (cylindrical shape, etc.) by cutting or the like.

It is preferable that the surface of the solid fuel is covered with paraffin. That is, the solid fuel is preferably sealed with paraffin. When the surface of the solid fuel is covered with paraffin, evaporation of the fuel component of the solid fuel can be prevented, and better storage stability tends to be obtained. In addition, while having the ignitability necessary for fuel, the solid fuel tends to be a safer solid fuel that prevents unintentional ignition of the solid fuel. It also tends to have a better shape when burned.

Paraffin is not particularly limited as long as it is a hydrocarbon, and examples thereof include chain saturated hydrocarbons such as hexadecane, heptadecane, octadecane, nonadecane, icosane, henicosane, docosane, tricosane, tetracosane, pentacosane, hexacosane, heptacosane, octacosane, and nonacosane. etc. These may be used alone or in combination of two or more.

The melting point of paraffin is preferably 40° C. or higher, more preferably 45° C. or higher, still more preferably 50° C. or higher, and preferably 80° C. or lower, more preferably 78° C. or lower, still more preferably 75° C. or lower.
As used herein, the melting point of paraffin is measured using a paraffin wax melting point tester in accordance with JISK2235 (2009).

The ratio of paraffin covering 100% of the surface area of the solid fuel is preferably 80% or more, more preferably 90% or more, still more preferably 95% or more, particularly preferably 98% or more, and most preferably 100%. %.

The thickness of the paraffin is preferably 0.1 mm or more, more preferably 0.2 mm or more, still more preferably 0.3 mm or more, preferably 2.0 mm or less, more preferably 1.5 mm or less, and still more preferably 1.3 mm or less.
In this specification, the thickness of paraffin is the average value of the measured values of five cut surfaces measured with a vernier caliper.

The method of covering the solid fuel surface with paraffin is not particularly limited, but for example, a method of spraying liquid paraffin on the solid fuel surface, a method of immersing in heated and dissolved liquid paraffin, etc. can be used.

The shape of the solid fuel is not particularly limited, but examples thereof include a cylindrical shape, a prismatic shape, a block shape, and a powdery shape. Among them, a columnar shape and a prismatic shape are preferable for the reasons of ignitability and stability of fire force.

The solid fuel may be filled in cans. For example, a product form in which a can is filled with solid fuel, the lid is opened while the can is kept in the can, and the solid fuel is ignited is also conceivable.

The solid fuel can be used for heat retention, heating, cooking, etc. of cooked foods. Among others, it is preferably used for heat insulation and heating of cooked food because of its suitable fire force and combustion time.

The weight of the solid fuel is not particularly limited, and may be appropriately set according to the purpose of use. If it is used for keeping or warming cooked food, it is preferably 3 to 70 g, more preferably 3 to 60 g, even more preferably 5 to 50 g.

When burning the solid fuel, the solid fuel is placed inside the tray, ignited and burned. A solid fuel having such a shape is suitable for keeping hot pot dishes that have already been cooked.

EXAMPLES The present invention will be specifically described based on Examples, but the present invention is not limited to these.

Various chemicals used in Examples and Comparative Examples are collectively described below. Chemicals not described below were purchased from reagent manufacturers.
Methyl cellulose: Metolose SM400 manufactured by Shin-Etsu Chemical Co., Ltd. (viscosity of 2% by mass aqueous solution at 20 ° C.: 400 mPa s)
Hexaglycerin stearic acid triester: SY Glister TS-5S manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.
Fragrance: D-limonene manufactured by Fujifilm Wako Pure Chemical Color powder: Savinyl Blue GLS manufactured by Clariant
Paraffin: paraffin manufactured by Yoneyama Pharmaceutical Co., Ltd. (melting point: 68-70°C)

(Examples and Comparative Examples)
<Production of solid fuel>
According to the composition shown in Table 1, each chemical was mixed for 10 minutes at 55 to 65° C. using a hot stirrer to obtain a solid fuel composition. Here, the fatty acid and sodium hydroxide were blended so that the fatty acid salt had the composition shown in Table 1. Moreover, in each formulation, the total amount was adjusted to 100 parts by mass.
After cooling and solidifying the obtained composition for solid fuel, it was cut and molded into a cylindrical shape to obtain a solid fuel.
In Examples 8, 9, 10, 18, and 25, 90% of the surface of the solid fuel was covered with paraffin by immersing it in paraffin heated and dissolved at 80°C (thickness of paraffin: 0.5 mm). ).
The following evaluation was performed using the obtained solid fuel, and the results are shown in Table 1.

(storability)
The solid fuel was dried by standing for 24 hours in an environment of 25° C. and 50% RH. The weight before and after the test was measured, and the weight reduction rate was calculated. Evaluation was made according to the following criteria.
◎: Weight reduction rate is less than 40% ○: Weight reduction rate is 40% or more and less than 70% ×: Weight reduction rate is 70% or more

(Solidity)
The solid fuel was compressed at 0.1 N/mm ² and observed for shape change and liquid seepage. Evaluation was made according to the following criteria.
◎: The shape does not collapse and the liquid does not ooze 〇: The shape does not collapse and the liquid oozes out slightly ×: The shape does not collapse and the liquid oozes out significantly or does not solidify

(ignitability)
A flame of an ignition lighter was applied to the upper surface of the solid fuel, and the time until ignition was measured. Evaluation was made according to the following criteria.
〇: Ignition time less than 2 seconds △: Ignition time 2 seconds or more and less than 10 seconds ×: No ignition

(fire force)
The solid fuel was placed on the stove and ignited, and an aluminum pan containing 300 mL of water was placed on the stove. The force of fire during combustion of the solid fuel and the state of boiling of water were visually observed. Evaluation was made according to the following criteria.
◎: Fire does not overflow from the stove and boils quickly 〇: Fire does not overflow from the stove and boils
×: Fire overflows from the stove or does not boil

(Odor during combustion)
The solid fuel was placed on the stove and ignited, and an aluminum pan containing 300 mL of water was placed on the stove. The smell was sniffed from a place 50 cm away from the stove. Evaluation was made according to the following criteria.
◎: No smell 〇: I feel a peculiar smell, but it is not unpleasant ×: I feel an unpleasant smell

(shape at the time of combustion)
The solid fuel was placed on the stove and ignited, and an aluminum pan containing 300 mL of water was placed on the stove. The condition of the solid fuel during combustion was visually observed. Evaluation was made according to the following criteria.
◎: Almost no liquefaction during combustion
○: Less than 30% liquefaction during combustion △: 30% or more and less than 50% liquefaction during combustion ×: The entire amount is liquefied during combustion

From Table 1, at least one monohydric alcohol (A) selected from the group consisting of methanol, ethanol, and propanol, and at least one selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, and glycerin Polyhydric alcohol and / or water (B) and a fatty acid salt (C) having 12 to 22 carbon atoms, the content of the monohydric alcohol (A) is 50 to 90% by mass, and the fatty acid salt It was found that the solid fuels of Examples having a content of (C) of 3 to 20% by mass are excellent in storage stability and can be suitably used as solid fuels.

Claims (9)

At least one monohydric alcohol (A) selected from the group consisting of methanol, ethanol, and propanol;
At least one polyhydric alcohol selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, and glycerin and/or water (B);
and a fatty acid salt (C) having 12 to 22 carbon atoms,
The content of the monohydric alcohol (A) is 50 to 90% by mass,
A solid fuel in which the content of the fatty acid salt (C) is 3 to 20% by mass. The solid fuel according to claim 1, wherein the polyhydric alcohol content is 1 to 40% by mass. 3. The solid fuel according to claim 1, wherein the water content is 1 to 40% by mass. The solid fuel according to any one of claims 1 to 3, which contains a thickening agent. 5. The solid fuel according to claim 4, wherein said thickening agent comprises polysaccharides. The solid fuel according to any one of claims 1 to 5, wherein the surface is covered with paraffin. 7. The solid fuel according to claim 6, wherein the paraffin has a thickness of 0.1-2.0 mm. The solid fuel according to any one of claims 1 to 7, wherein the fatty acid salt (C) is a fatty acid salt having 16 to 20 carbon atoms. The monohydric alcohol (A) is methanol,
the polyhydric alcohol and/or water (B) are ethylene glycol and/or diethylene glycol and water;
The fatty acid salt (C) is a stearate,
2. The solid fuel of claim 1, further comprising methylcellulose.