JPH11293234A - Cold and heat storage agent and cold and heat storage material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cold and heat storage agent prepared by dispersing and mixing a cold storage agent and a heat storage agent and a cold, and heat storage material prepared by packing the cold and heat storage agent into e.g. a container. SOLUTION: Water as a base (100 pts.wt.) is mixed with a necessary amount of sodium chloride as a freezing agent and mixed with 3 pts.wt. carbocymethylcellulose as a gelling agent to obtain a cold storage agent having a melting point of 0 to -25 deg.C. The cold storage agent may additionally contain a uncleator such as silver iodide or metaldehyde. The cold storage agent is mixed with as a heat storage agent 50 pts.wt. microcapsules in which the core material is a petroleum wax having a melting point of 16 deg.C and the shell material is gelatin to prepare a cold and heat storage agent. The cold and heat storage agent is packed into a flat container made of a plastic such as a high- density polyethylene to form a cold and heat storage material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention particularly relates to a cold storage agent containing a cold storage agent containing water as a main component and a microcapsule containing a heat storage agent as a core agent, and a cool / heat insulating material using the same. The regenerative heat storage agent of the present invention is stored in an appropriate container such as a plastic material, and is used to keep frozen products, fresh foods, pharmaceuticals, etc., to cool when a person generates heat, or to transport and store foods that require heat retention. For use in a wide range of business applications, such as medical and home use, heat storage air conditioning systems for buildings, buildings, etc., heat storage air conditioning systems for cars, buses, trucks, etc., and cooling and heating systems during intermittent operation. Can be.

[0002]

2. Description of the Related Art Heretofore, a regenerator containing water having a large latent heat of fusion as a main component and an appropriate amount of a cryogen, a gelling agent, and a nucleating agent as required has been frequently used. On the other hand, heat storage agents composed of natural wax, petroleum wax and the like are also well known. The regenerator is used only for the purpose of keeping the temperature below a predetermined temperature, and the regenerator is used only for the purpose of keeping the temperature above the predetermined temperature.

[0003] Therefore, attempts have been made to mix these regenerators and regenerators to produce regenerators that can be used in any of cold storage and heat retention applications. However, there is a problem that water, which is a main component of the regenerator, and paraffins, which are often used as a regenerator, are not compatible at all and cannot be uniformly mixed because they are separated from each other. In addition, they can be dispersed and mixed by mixing a surfactant, but cannot be maintained in a stable dispersed state by being separated during repeated freezing, thawing, thawing and coagulation.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems. In particular, the present invention relates to a regenerator containing water as a main component and a microcapsule containing a core material such as wax as a regenerator. An object of the present invention is to provide a cold storage agent in which a cold storage agent and a heat storage agent are uniformly dispersed and mixed. Another object of the present invention is to provide a cool / heat insulating material in which the cold storage agent is stored in an appropriate container.
By using this microcapsule, even without using a surfactant, the cold storage agent and the heat storage agent can be easily and uniformly dispersed and mixed, and even after repeated freezing and thawing,
The components of the regenerator such as water do not separate from the microcapsules.

[0005]

The regenerative heat storage agent of the first invention comprises:
It is characterized by containing a regenerator having a constant heat of fusion and a regenerator having a constant heat of solidification. In addition, the cool storage agent of the fourth invention is characterized by containing a cool storage agent and microcapsules having the heat storage agent as a core agent. These first
And in the regenerator according to the fourth invention, as in the second and fifth inventions, even after repeating at least one of freezing and thawing of the regenerator and melting and coagulation of the regenerator, the regenerator and the regenerator can be used. The agent, in particular, the fifth invention is characterized in that the regenerator and the microcapsules are maintained in a dispersed and mixed state without being separated from each other.

[0006] As the above-mentioned "cool storage agent", those which freeze in a short time, require less energy for freezing, and have a long effective cold-retention time are preferable. Those containing a cryogen, a gelling agent and the like are often used. When these regenerators are in a supercooled state, it takes a long time to freeze and requires a large amount of energy. Therefore, a nucleating agent is often blended so as to freeze quickly near the freezing point. If necessary, a nucleating agent may be added to the regenerator of the invention.

[0007] As the cryogen, metal salts of inorganic acids such as sodium chloride, potassium chloride, calcium chloride, magnesium chloride and potassium nitrate can be used. Further, polyhydric alcohols such as ethylene glycol and propylene glycol can also be used. The melting point of the regenerator can be adjusted by adjusting the amount of the refrigerating agent, and the regenerator having a melting point of 0 to -30 ° C according to the third invention can be easily prepared. The melting point of this regenerator is particularly 0 to -25 ° C.
It can be used in any application, from vegetables and fruits transported and stored in a temperature range of 0 to 15 ° C. to frozen foods transported and stored at lower temperatures. .

As the gelling agent, there can be used hydrophilic polymers such as carboxymethylcellulose, polyvinyl alcohol, sodium polyacrylate, polyacrylamide and the like, and water-insoluble superabsorbent polymers obtained by crosslinking these polymers. In addition, natural polysaccharides such as gelatin, aerosil, starch, and guar gum can also be used. The amount of the gelling agent can be 0.01 to 10 parts by weight, based on 100 parts by weight of the regenerator. The amount is particularly preferably 0.01 to 5 parts by weight, more preferably 0.01 to 3 parts by weight. In addition, as the ratio of the gelling agent decreases, the viscosity of the regenerator decreases, and the handleability when the regenerator is filled in a container is improved. Therefore, the amount may be reduced to 0.5 part by weight or less, or even 0.1 part by weight or less, while taking other characteristics into consideration.

By using a small amount of the gelling agent as described above, and especially by using the gelling agent in an amount of 0.2 parts by weight or less, the viscosity of the obtained regenerator at room temperature becomes considerably low, It is possible to obtain a regenerator that is easy to handle and has excellent properties. When the gelling agent is blended, even if the blending amount is 10 parts by weight, the viscosity of the regenerator is so high that it cannot be measured with a B-type viscometer, and if it exceeds 10 parts by weight,
The viscosity of the regenerator further increases, and the workability during handling, such as filling in a container, is greatly reduced.

The nucleating agent serves as ice crystal nuclei for freezing the regenerator, and includes suiloids such as silver iodide, copper sulfide, xanthan gum and cholesterol, and methaldehyde, α
-Inorganic or organic compounds such as phenazine, sodium pyrophosphate can be used. In addition, as the nucleating agent, bacteria having activity as a certain nucleating agent, microorganisms such as marine phytoplankton, moss, and the like can also be used. These nucleating agents are, for 100 parts by weight of water, 0.001 to 0.003 parts by weight of the inorganic or organic compound,
In the case of bacteria, etc., 10 ^{-6 to} 0.1 parts by weight can be added.

As the "heat storage agent", various waxes can be used. Wax is a low-molecular-weight polymer that is solid at normal temperature and becomes a low-viscosity fluid upon heating, and can be appropriately selected from natural wax, petroleum wax, and the like. There are various types of natural wax and petroleum wax having different melting points, and those having a required melting point can be easily obtained, which is preferable. As the wax, petroleum wax such as paraffin wax or petrolatum separated and refined from distillate obtained by distillation of heavy oil under reduced pressure or heavy distillate, etc. is frequently used. The paraffin wax has a carbon number distribution of 20 to 6 such as normal paraffin, isoparaffin and cycloparaffin.
0, hydrocarbon compounds having a number average molecular weight of 300 to 800, derivatives thereof, and the like.

There are various waxes having different melting points, and a heat storage agent that can be used as a heat insulator in a required temperature range can be easily prepared. As the heat storage agent, those having a melting point of 15 to 70 ° C. according to the third invention are particularly preferable. In addition, the melting point of the heat storage agent can be particularly set at 15 to 50 ° C., and by using the heat storage agent and the cold storage agent having a melting point of 0 to −30 ° C., it is necessary to keep cold or heat. It can be used in a wide range of applications.

The regenerators of the first to third inventions contain a regenerator and a regenerator, but they do not separate from each other. In particular, the regenerator does not separate even after repeated freezing and thawing. It is necessary to use a heating agent. Such a cold storage agent can be prepared by using microcapsules having a heat storage agent as a core agent as in the fourth invention. In particular, as in the sixth invention, by blending microcapsules using wax as a core agent with a regenerator containing water and a cryogen, a regenerative agent that can stably maintain a uniform dispersion state can be easily prepared. Obtainable.

The shell constituting the microcapsule is formed of a shell material whose heat-resistant temperature is sufficiently higher than the melting point of the heat storage agent used. The shell material preferably has a heat-resistant temperature higher than the melting point of the heat storage agent by 30 ° C. or more, particularly 50 ° C. or more. As such a shell material, a synthetic resin such as a melamine resin, an acrylic resin, or a urethane resin can be used. In addition, gelatin, gelatin arabic, carboxycellulose, polyoxymethylene urea, aminoplast, cellulose acetate phthalate, ethyl cellulose, polyethylene-vinyl acetate, polyvinyl alcohol and the like can also be used. Of these, polyoxymethylene urea is particularly preferable, and a microcapsule which is easy to form a shell and has sufficient strength can be obtained.

It is preferable that the amount of the heat storage agent as the core agent included in the shell is large from the viewpoint of the heat storage effect. But,
If the amount is too large, the shell may be damaged due to volume expansion of the heat storage agent. Therefore, the ratio of the amount of the heat storage agent to the total weight of the microcapsules is preferably set to 30 to 90% by weight. This ratio is particularly preferably 50 to 90% by weight, more preferably 60 to 80% by weight. In addition, the outer diameter of microcapsules is several μm.
m to several 1000 μm can be used, but those having an outer diameter of 100 to 1000 μm, particularly 200 to 500 μm, and more preferably 250 to 450 μm are more preferable. A microcapsule having an outer diameter in this range can be easily and uniformly mixed with components of a regenerator such as water, a cold agent, and a gelling agent.

As a method for producing microcapsules, an interfacial polymerization method, an in-situ polymerization method, a coacervation method, and the like are known. These production methods can be appropriately selected depending on the material of the heat storage agent and the shell as the core agent, and the like. In the present invention, microcapsules obtained by any of the production methods can be used without any particular problem. However, as in the sixth and eighth inventions, when a wax is used as a core agent, a coacervation method is used. It is preferable to manufacture by.

According to a seventh aspect of the present invention, there is provided a cool / heat insulating material, wherein a cold storage agent and microcapsules having a heat storage agent as a core agent are dispersed, mixed, and stored in a container.

As the "container", a container made of plastic, metal or the like can be used, but a plastic container is usually used. As the plastic, those which do not affect the components of the regenerator such as water, cold agent and gelling agent and the components of the heat storage agent such as wax and which are not affected by these components can be used. In addition, a material having the required heat resistance corresponding to the melting point of the heat storage agent and not causing low-temperature embrittlement even when exposed to a temperature below freezing for a long time can be used. Such plastics include low density polyethylene, high density polyethylene,
Polyolefins such as polypropylene, polyvinyl chloride,
Examples thereof include polyamides such as 6-nylon and 66-nylon. Further, the shape of the container is not particularly limited, but a flat rectangular shape is usually used from the viewpoint of handling or cooling efficiency.

The above-mentioned container is often manufactured by a blow molding method. As described above, if a regenerative heat storage agent of the present invention having a particularly low viscosity is used, the molded product can be placed in a mold. While being held, the inside thereof can be easily filled with the cold storage agent. As described above, the molding of the container and the filling of the cold storage agent can be performed in-line, and the cool / heat insulating material of the seventh invention can be obtained efficiently and easily.

Incidentally, in the case of a cold storage agent mainly composed of water,
Its volume usually increases by about 10%. There is no particular problem if this increase in volume is evenly distributed over the entire surface of the cool / heat insulating material.However, this concentrates on a specific part, and a projection is generated at that part, and in some cases, the container is damaged. Sometimes. Generation of such projections or breakage of the container can be prevented by adding an appropriate amount of alcohol to the regenerator.

Examples of the alcohols include monoalcohols such as methyl alcohol and ethyl alcohol, and polyhydric alcohols such as ethylene glycol, propylene glycol and glycerin. These alcohols can be blended in water in the required amount corresponding to the melting point of the regenerator. As the alcohols, glycol is preferable from the viewpoint of preventing concentration of volume increase due to freezing. In particular, when the cooling / heating material is used for foods and the like that require safety and hygiene considerations, propylene glycol is preferably used.

The amount of the alcohol compounded is 100
0.01 to 20 parts by weight, especially 0.1 to 20 parts by weight.
It is preferably from 0.5 to 3 parts by weight, more preferably from 1.5 to 2.5 parts by weight. If the amount of the alcohol is less than 0.01 parts by weight, concentration of the volume increase due to freezing cannot be effectively prevented. When 20 parts by weight are added, concentration of volume increase due to freezing can be sufficiently prevented, and it is not necessary to add a larger amount of alcohols. In addition, since these alcohols also act as a cryogen, it is necessary to determine the blending amount in consideration of this point.

The regenerator agent constituting the regenerator agent according to the present invention comprises:
Water and cold agent are essential components, and a gelling agent, a nucleating agent, etc. are blended with this, but if necessary, preservatives, fungicides, color pastes, etc., usually used for this kind of cold storage agent Additives to be added. The amount of these additives can be set to such an extent that the properties of the regenerator are not impaired.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to examples. (1) Performance Evaluation as Cooling / Heat Insulating Material Examples 1 to 4 A required amount of sodium chloride was blended as a cold agent with 100 parts by weight of water as a main agent, and 3 parts by weight of carboxymethyl cellulose was blended as a gelling agent. Thus, four types of regenerators having melting points of 0 ° C. (Example 1), −5 ° C. (Example 2), −15 ° C. (Example 3), and −25 ° C. (Example 4) were obtained. Then, a microcapsule (trade name “Thermasorb 65”, manufactured by Frisby Technologies, trade name: petroleum wax having a melting point of 18 ° C.) containing 75 parts of petroleum wax as a core agent and gelatin as a shell agent was used as a heat storage agent.
% By weight, the average particle size of which is 500
μm. ) 50 parts by weight were blended to prepare a cold storage agent.

Next, 100 g of this regenerative heat storage agent
A 0 mm spherical body was wrapped with a thin film of polyvinylidene chloride to prepare a cooling / heating material. After that, the cool / heat insulating material is allowed to stand in a freezer set at -40 ° C for 10 hours to be frozen, and after freezing, the temperature of the cold storage agent when exposed to an external temperature of 30 ° C is measured over time. Was measured. The measurement of this temperature was performed by a thermocouple inserted in the container. The thermocouple used was a K 1.5 class thermocouple specified in JIS C 1602. The results are shown in FIG.

According to FIG. 1, with the four types of regenerators, the temperature was first raised for 1 to 3 hours and then 0 ° C., −5 ° C., −15 ° C. and −25 ° C., which are the melting points of the respective regenerators. A flat portion without temperature rise is observed for several hours in the vicinity of. Also, after all the regenerators have melted, the temperature starts to rise,
Although there is some variation in temperature, near the melting point of the heat storage agent,
Again, a flat part without temperature rise is observed over several hours. Then, after all the heat storage agents have been melted, the temperature has started to rise toward 30 ° C., which is the outside temperature. As described above, in the cold / heat insulating material containing the cold storage agent of the present invention, there is a region where the temperature hardly changes for a certain period of time due to latent heat in both the temperature range below the freezing point and the high temperature of 0 ° C., particularly 10 ° C. or more. In addition, it can be seen that they have both functions of cooling and warming.

(2) Performance comparison with the case of using only the regenerator and only the regenerator, and the influence of the heat cycle The regenerator of Example 4, only the regenerator having a melting point of 0 ° C. (Comparative Example 1) and 100 g of only the heat storage agent having the above melting point of 18 ° C. (Comparative Example 2) was wrapped with a thin film of polyvinylidene chloride and placed in a freezer set at −40 ° C.
The mixture was allowed to stand for 0 hours to freeze, and after freezing, the temperature of the regenerative heat storage agent and the like was measured over time when a heat cycle of exposing it to an external temperature of 30 ° C. for 12 hours was repeated three times. The temperature was measured in the same manner as in the above (1). The results are shown in FIG. still,
FIG. 2 shows the results of two heat cycles,
The results of the third round are substantially the same.

According to FIG. 2, in the case of the cooling / heating material of Example 5, a relatively flat portion without a temperature rise near 0 ° C. and 18 ° C. is observed at the first temperature rise. Also, in the step of freezing again, it is not as clear as when the temperature is raised, but it is 0 ° C.
And a relatively flat portion having no temperature drop near 18 ° C. On the other hand, when only the regenerator having a melting point of 0 ° C. in Comparative Example 1 is used, a relatively flat portion where there is no change in temperature only near 0 ° C. is observed both when the temperature is increased and when the temperature is decreased. When only the heat storage agent having a melting point of 18 ° C. in Comparative Example 2 was used, a relatively flat portion where the temperature did not change only at around 18 ° C. was observed both when the temperature was raised and when the temperature was lowered. Such a tendency was almost the same in the second heat cycle.

As described above, in the cold / heat insulating material containing the cold storage heat agent of the present invention, the temperature hardly changes for a certain time due to latent heat in the high temperature region below the freezing point and at 0 ° C., particularly at 10 ° C. or more. It can be seen that the performance is not changed even by the heat cycle. In addition, when the cold storage agent in the bag-shaped container was visually observed when it was put into the freezer and when it was taken out of the freezer, there was no appearance of separation of the cold storage agent and the microcapsules.

[0030]

According to the first aspect of the present invention, the regenerator and the regenerator are uniformly dispersed and mixed. In particular, even after freezing and thawing are repeated as in the second aspect of the present invention, the regenerator and the regenerative agent are repeatedly mixed. dispersion,
It is possible to obtain a regenerative agent having excellent performance in which a mixed state is maintained. According to the fourth invention, in particular, as in the sixth invention, by using microcapsules having a heat storage agent such as wax as a core material, the heat storage agent and the heat storage agent can be more easily and uniformly dispersed. , Can be a mixed cold storage agent.

Further, according to the seventh invention, a cold storage agent is added to a container made of plastic or the like, and particularly, as in the eighth invention,
By storing microcapsules using a heat storage agent such as wax as a core material, it is possible to easily obtain a cooling / heating material excellent in cooling / heating effects.

[Brief description of the drawings]

FIG. 1 is a graph showing the effects of cooling and heat retaining of a cooling / heating material.

FIG. 2 is a graph showing that there is no change in the effect of keeping cold and keeping heat even with a heat cycle.

Claims (8)

[Claims] 1. A regenerative agent comprising a regenerative agent having a constant heat of fusion and a regenerative agent having a constant heat of solidification dispersed and mixed. 2. The state of dispersion and mixing of the regenerator and the regenerator after at least one of freezing and thawing of the regenerator and melting and coagulation of the regenerator is repeated. Item 8. The cold storage agent according to Item 1. 3. The heat storage agent has a melting point of 0-30 ° C., and the heat storage agent has a freezing point of 15-70 ° C.
Or the cold storage agent according to 2. 4. A cold-storage agent comprising a cold-storage agent and microcapsules having a heat-storage agent as a core dispersed and mixed. 5. The state of dispersion and mixing of the cold storage agent and the microcapsules even after repeating at least one of freezing and thawing of the cold storage agent and melting and solidification of the heat storage agent. Item 5. The cold storage agent according to Item 4. 6. The cold storage agent according to claim 4, wherein the cold storage agent includes water and a cryogen, and the heat storage agent is a wax. 7. A cooling and heat retaining material characterized in that a regenerator and microcapsules having a regenerator as a core agent are dispersed, mixed, and stored in a container. 8. The cooling / heating material according to claim 7, wherein said regenerator contains water and a cryogen, and said regenerator is wax.