JP4173620B2 - Granulated product and heating method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a granulated product having a heat storage performance capable of heating or keeping an object without continuously using energy from electricity or fuel, and a heating method thereof. The packing material filled with the granulated product can be used as a heating device in a cold place for the same use as conventionally known warmers, hot water bottles, fires and the like. The powder having the heat storage performance of the present invention has a heat retention effect that lasts for a long time by heating once.
[0002]
[Prior art]
As a heat insulating material that is used without using energy of electricity or fuel, particularly as a heat insulating material for warming up in the cold, there are a warmer, a fire, a hot water bottle and the like. Recently, disposable chemical warmers using the oxidation reaction of iron powder have been accepted into the large market because of their simplicity and low cost, but there is a problem that they cannot be reused or finely regulated.
[0003]
A hot water bottle is generally used as a heat storage type heating tool. A hot water bottle is a heat storage type heat insulation material that uses the sensible heat of water (hot water). However, it is not easy to boil or fill hot water, there is a risk of burns, and the heat retention is inferior to the weight. Has drawbacks. Generally, as a means for extending the duration of the heat storage type heat insulating material, it is only necessary to increase the heat capacity of the heat insulating material. 1. Increase the amount of heat storage material (hot water in the case of hot water bottles). There are methods such as using a compound having a phase change instead of water, that is, a latent heat storage material.
[0004]
However, 1. In this method, the weight of the heat insulating material is increased, and it takes time and a great deal of energy to boil hot water as a heat storage material as well as difficulty in carrying. On the other hand, 2. In order to realize this method, a compound having a melting point of at least 30 ° C., for example, a latent heat storage material such as an inorganic eutectic salt or paraffin wax is put into a hot water bottle instead of hot water. Taking out at a temperature of 1 is complicated, and there is a lack of practicality such as a risk of ignition when heating.
[0005]
In order to solve the above-mentioned problem, the present inventor disclosed in Japanese Patent Application Laid-Open No. 8-19564 has a long suitable temperature by heating a heat insulating material filled with an aqueous dispersion of microcapsules containing a heat storage material. A heat insulating material that lasts for a long time was proposed. Furthermore, this heat insulating material is characterized in that it can be easily heated by irradiation with microwaves emitted from a microwave oven or the like. However, as a problem in use, if microwaves are continuously irradiated excessively, the moisture of the contents gradually evaporates, and there is a risk that the packaging material may be damaged due to expansion. In addition, since the water occupies almost half, the content of the latent heat storage material does not increase, or it is difficult to be portable.
[0006]
[Problems to be solved by the invention]
The problem of the present invention is that it does not require the operation of pouring hot water as was done in a conventional hot water bottle, and can repeatedly store and release heat with a simple operation, and has a heat storage performance with a long heat retention time. It is to obtain a granule, and at the same time, to provide a safe heat insulating material that does not expand or deform even when irradiated with a microwave for a long time.
[0007]
[Means for Solving the Problems]
The above object is achieved by obtaining a granulated product comprising a silica gel pigment having specific properties and a microcapsule enclosing a heat storage material. In other words, this granulated product is heated alone and in a short time by filling it with a suitable packaging material and irradiating microwaves, and the heat is transferred to the microcapsules that are in direct or indirect contact. Heat storage is possible. The present invention is used to obtain a granulated product in which a microcapsule enclosing a latent heat storage material and a specific silica gel pigment are mixed, and the powder is irradiated with microwaves and heated to be used as a heat storage material. The
[0008]
A microcapsule is a minute container having a diameter of about 0.1 μm to several mm, and is always liquid regardless of the phase change state of the heat storage material as long as it is dispersed in the liquid. In general, the smaller the particle size of the microcapsule, the stronger the strength, and the weaker the larger the particle size, the weaker it becomes during the drying process or subsequent handling, and it is necessary to set an appropriate particle system. The range of 0.5 to 50 μm, more preferably 1 to 20 μm is preferable. The average particle system of microcapsules and the average particle diameter of silica gel indicate a volume average particle system measured using a particle size measuring device Multisizer II type manufactured by Coulter USA.
[0009]
The silica gel pigment mixed together with the microcapsules in the present invention refers to hydrous silicic acid obtained by reacting sodium silicate with mineral acid, and has many silanol groups on the particle surface and inside, and water is electrically or It is physically adsorbed in the pores between the pigment particles. In the present invention, by irradiating the silica pigment with microwaves, the movement of the water molecules bound thereto becomes active and heat is generated.
[0010]
Although the heat loss of the silica pigment used in the present invention is affected by the temperature and humidity of the environment maintained so far, it is preferably in the range of 1 to 30% in the present invention. If the value is lower than this range, sufficient heat generation cannot be obtained by microwave irradiation. Conversely, if the value is higher than this range, granulation becomes difficult. The weight loss by heating described in the present invention represents a numerical value obtained based on a test method according to JIS K5101, 23, and specifically represents a weight loss rate after heat treatment at 105 ° C. for 2 hours.
[0011]
The particle diameter of the silica gel pigment is 50 μm or less, preferably 20 μm or less. If the particle size is within this range, the contact area with the microcapsule particles is small, and the heat generated is not easily transmitted, which is not preferable.
[0012]
In addition to the silica gel pigment used in the present invention, inorganic salts such as calcium chloride, magnesium chloride, aluminum sulfate, bentonite, kaolin, fuller's earth, acid clay, activated clay, montmorillonite, attapulgite, sepiolite, In addition to clay favorite pigments such as halloysite, pyrophyllite, sericite, vermiculite, chlorite, and allophane, an ultrafine colloidal silica dispersion may be used in combination.
[0013]
The method for producing a granulated product of the present invention can be granulated by mixing a silica gel pigment and microcapsules previously powdered, but it requires a step of powdering the microcapsules. On the other hand, the present inventor adsorbs water, which is a dispersion medium of microcapsules, to the silica gel pigment by appropriately mixing a silica gel pigment having a specific surface area of 40 m ² / g or more and a microcapsule dispersion having a solid content of about 20% or more. It has been found that fluidity is easily lost, it becomes easy to form a wet solid that can be molded, and it can be processed into any shape. In addition, the specific surface area in this invention says the value obtained based on the adsorption | suction method of BET.
[0014]
The wet solid thus obtained is processed into a desired size and shape through a granulation step. The granulation method differs depending on whether the sample is a powder or a wet product, but various granulation methods such as a top plate granulation method, an extrusion granulation method, a roll compression granulation method, a tableting granulation method, etc. However, it is necessary to select an apparatus and conditions that do not damage the microcapsules. Preferably, an extrusion-type granulation method in which a molded product is continuously extruded from a hole having a constant diameter is preferable. The shape of the powder may be any shape such as a sphere, an ellipse, a cube, a rectangular parallelepiped, a cylinder, a cone, a bowl, a regular polyhedron, a star, and a cylinder. The size is molded into a granular form having a maximum diameter of 100 μm to 100 mm. If the size is less than this range, the powder is likely to fly up and adhere to the container, and if it is more than this range, it is difficult to fill the packaging material.
[0015]
The mixing ratio of the solid weight of the silica gel pigment and the microcapsule can be set to any ratio depending on the purpose, but the heat retention is improved by increasing the weight ratio of the microcapsule, and the ratio of the water-absorbing pigment is increased by the microwave. Since rapid heating becomes possible, it is freely set according to the purpose.
[0016]
The latent heat storage material that can be used in the present invention is a compound having a melting point in a temperature range in which a comfortable heat can be felt when in contact with the human body, although any inorganic or organic material can be used as long as it is a compound with phase change. Is preferably about 30 ° C. or higher. Specifically, inorganic compounds containing a large amount of crystal water such as magnesium chloride hexahydrate, sodium acetate trihydrate, magnesium nitrate dihydrate, and the like. Examples include aliphatic hydrocarbons, aromatic hydrocarbons, higher fatty acids such as stearic acid, myristic acid and lauric acid, higher alcohols such as cetyl alcohol and stearyl alcohol, and organic compounds such as phenyl benzoate and dicyclohexyl phthalate. Although it is used individually or in mixture of 2 or more types, it is not limited to these.
[0017]
The method of microencapsulation of the latent heat storage material varies depending on the properties of the latent heat storage material used, but typical methods and film materials include gelatin coating by coacervation, melamine resin by in situ method, urea formalin coating, interface Known methods and film materials such as polyurethane, nylon or polyurea resin film by polymerization method, resin film by in-liquid drying method and the like can be mentioned. In general, since the coating temperature of the microcapsule that encloses the heat storage material is required to be heat-resistant because the temperature may locally become considerably high due to microwave irradiation, an in-situ method that provides a highly heat-resistant coating can be obtained. A melamine-formalin resin microcapsule by the chew method is particularly preferred. A supercooling prevention material, a specific gravity adjusting material, a deterioration preventing agent, a flame retardant, a colorant, a fragrance, a photocatalytic functional material, a dispersion auxiliary material, and the like can be added to the inside or outside of these microcapsules.
[0018]
In addition to the silica gel pigment and microcapsules necessary for the production of the granulated product of the present invention, a binder is added if necessary. The binder is required to be thermally stable and to be a material that does not adversely affect microwave heating. Conventionally known natural polymer materials, natural polymer modified products (semi-synthetic products), and synthetic products can be used as the binder.
[0019]
The granulated product of the present invention can be filled in a packaging material suitable for the purpose. Specific examples of the packaging material include synthetic or natural materials such as polyethylene, polypropylene, polyester, polyurethane, polyurea, nylon, and natural rubber, in addition to natural fibers such as cotton, wool, and silk. The shape and size of the packaging material are not particularly limited, and are processed into a form suitable for the intended use. The surface of the packaging material gradually becomes hot due to the microwave irradiation, so that it touches the human body by covering the outside of the packaging material with a material that can cut off the heat to some extent and keep it warm, for example, a cloth bag with an appropriate thickness. In some cases, the feeling of use is improved and the duration of heat generation can be adjusted.
[0020]
Microwaves are usually called high-frequency waves, and when a liquid having polarity is irradiated, the molecular motion becomes active and heating is possible. The most common microwave irradiation device is a microwave oven, and a high frequency emitted from a magnetron is generally used. The method for heating the powder according to the present invention is not limited to microwave irradiation, but heat can be stored in the same manner by heating until the heat storage material melts in hot water having a temperature equal to or higher than the melting point of the latent heat storage material. A microwave heating method is preferable in that the powder can be rapidly heated to a high temperature.
[0021]
【Example】
Next, examples of the present invention will be described.
Example 1
80 g of paraffin wax having a melting point of 50 ° C. as a latent heat storage material was added to 100 g of an aqueous sodium salt solution of 5% styrene-maleic anhydride copolymer adjusted to pH 4.5 with vigorous stirring. The emulsion was emulsified until it reached 5.0 μm. Next, 5 g of melamine, 7.5 g of 37% formaldehyde aqueous solution and 15 g of water were mixed, adjusted to pH 8, and a melamine-formalin initial condensate aqueous solution was prepared at about 80 ° C. The whole amount was added to the emulsion, and the mixture was heated and stirred at 70 ° C. for 2 hours to adjust the pH to 9 to complete the microencapsulation reaction. The volume average particle diameter of the obtained microcapsules was 5.2 μm.
[0022]
100 parts of the above microcapsule dispersion liquid adjusted to a solid content concentration of 40% (w / w) with water, 20 parts of hydrous silicate powder having a specific surface area of 400 m ² / g, loss on heating of 4.5%, and an average particle diameter of 2 μm By gradually adding the mixture while kneading with a kneader, a wet solid was obtained. After obtaining this granulated material having a longest diameter of about 5 mm using an extrusion granulator having a structure as shown in FIG. 1, it was dried at an ambient temperature of 100 ° C. for 1 hour to complete the granulated material. .
[0023]
100 g of this granulated product was filled into a breathable nonwoven fabric bag made of polyester fiber having a thickness of 0.5 mm to obtain a heat insulating material for thermotherapy. When this heat insulating material was heated in a home microwave oven with a high frequency output of 500 W for 2 minutes and then applied to the lower back of the human body, a pleasant warm heat persisted for a long time.
[0024]
Example 2
80 g of myristyl myristate having a melting point of 40 ° C. was vigorously stirred in 100 g of a 5% ethylene-maleic anhydride copolymer sodium salt solution in which 5 g of urea and 0.5 g of resorcin were dissolved and the pH was adjusted to 3.0. The emulsion was added until the average particle size was 10 μm. Next, 14 g of 37% formaldehyde aqueous solution and 20 g of water were added to this emulsion, and the mixture was heated and stirred at 60 ° C. for 2 hours to carry out an encapsulation reaction. Then, the pH of this dispersion was adjusted to 9 to complete the encapsulation. did. The volume average particle diameter of the obtained microcapsules was 10.2 μm.
[0025]
100 parts of the above microcapsule dispersion adjusted to a solid content concentration of 40% (w / w) with water is 40 parts of hydrous silicate powder having a specific surface area of 55 m ² / g, loss on heating of 6.5% and an average particle system of 12 μm. By gradually adding the mixture while kneading with a kneader, a wet solid was obtained. After obtaining this granulated product having a longest diameter of about 80 mm using an extrusion granulator having a structure as shown in FIG. 2, the granulated product was completed by drying at an atmospheric temperature of 100 ° C. for 1 hour. .
[0026]
Comparative Example 1
Instead of the hydrous silicate pigment used in Example 1, an attempt was made to obtain a wet solid in the same manner using calcium carbonate having a specific surface area of 20 m ² / g. Grain manipulation was not possible.
[0027]
Comparative Example 2
In place of the hydrous silicate pigment used in Example 1, an attempt was made to obtain a wet solid in the same manner using silica gel particles having a diameter of 2 mm.
[0028]
【The invention's effect】
The granulated product according to the present invention can be used as a solid heat storage material, and once heated, it can maintain warmth for a long time. Moreover, it is not necessary to fill or unplug hot water like a conventional hot water bottle, and it can be used safely any number of times by simply irradiating it with microwaves. Furthermore, the touch always maintains softness.
[Brief description of the drawings]
FIG. 1 is a schematic view of an extrusion granulator used in Example 1. FIG.
2 is a schematic view of an extrusion granulator used in Example 2. FIG.
[Explanation of symbols]
1 Heat storage material microcapsule before granulation 2 Solid heat storage material after granulation

Claims (5)

A granulated product comprising a silica gel pigment having a specific surface area of 40 m ² / g or more and a heat loss of 1 to 30% and a microcapsule containing a heat storage material, and having a longest diameter of 100 μm to 100 mm. A granulated product obtained by mixing a dispersion of microcapsules encapsulating silica gel pigment and a heat storage material to make it a solid material in a wet state by losing its fluidity and then molding it using an extrusion granulator. The granulated product according to claim 1, wherein the silica gel pigment has an average particle size of 50 µm or less. The granulated product according to claim 1, wherein the film of the microcapsule is a melamine formalin resin or a urea formalin resin. A method of heating and storing the granulated product according to claim 1 or a filler thereof by microwave irradiation.

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