JP2008156582A - Refrigerant and refrigerant pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerant which has a lasting cooling ability and, even when the pack has a hole, does not leak out of the hole. <P>SOLUTION: The refrigerant comprises at least water, salt and a water-absorbing polymer. The mixing ratio of water to the salt is 95-99 pts.wt. of water and 1-5 pts.wt. of the salt, relative to 100 pts.wt. of the sum of water and the salt. The mixing ratio of the water-absorbing polymer is 2.3-4.6 pts.wt. to 100 pts.wt. of water and the salt in aggregate to gelatinize the refrigerant. The salt comprises at least one of sodium chloride, potassium chloride and sodium sulfate. The water-absorbing polymer is sodium polyacrylate with a crosslinked structure. The cooling capacity of the refrigerant is not less than 4 hours at +3°C. As is gelatinized, the refrigerant does not leak out of the pack, even when it has a hole. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cold-retaining agent, and more particularly, to a cold-retaining agent that can be kept cold for a long time at a temperature of about 0 ° C. or lower and a cold-reserving agent pack using the cold-retaining agent.

  Conventionally, various types of cooling agents such as water, potassium chloride, sodium chloride, polyethylene glycol, and dry ice are known. Moreover, the technique disclosed by the following patent document 1 can also be seen as one of the prior arts of a cryogen.

  FIG. 13 and FIG. 14 are graphs showing the relationship and performance, etc. with the blending amount of the cryogen described in Patent Document 1, and FIG. 13 is a blending time of −26 to −22 ° C. and the blending of sodium chloride and potassium chloride. FIG. 14 is a graph showing the relationship between the temperature change of the cooling agent and the elapsed time. In Patent Document 1, it is expressed as a cold storage agent, but here it will be described as a cold storage agent.

  According to Patent Document 1, in FIG. 13, the blending ratio of sodium chloride and potassium chloride in the A zone is a preferable blending ratio because the cooling time in the temperature range of −26 to −22 ° C. is 35 minutes or more. It is said. And in FIG. 14, it is shown that the cold-retaining time at −22 ° C. or lower has about 50 to 55 minutes. Further, in FIG. 13, the blending ratio of the B zone is not preferable because the cooling time is 35 minutes or less, and the difference from the conventional one becomes small. In addition, the blending ratio of the C zone exceeds the limit of solubility and causes precipitation, which is not preferable.

  In general, a refrigeration agent blended with sodium chloride, potassium chloride, and water to be iced is often packed in a bag and used. Hereinafter, the cold storage agent packed in a bag will be referred to as a cold storage pack. In the state of the cryogen pack, it becomes easy to keep food in cold packaging, and great convenience can be obtained in packaging, transportation and storage.

  JP 2002-129151 A

  Here, as a result of conducting various tests on the cryogen, the present applicant has found the following. A part of the result will be described with reference to FIGS. Here, FIG. 15 is a graph showing the relationship between the temperature and time of the cryogen composed of sodium chloride and water, and FIG. 16 shows the relationship between the temperature and time of the cryogen composed of potassium chloride and water. A graph and FIG. 17 are graphs showing the relationship between the temperature and the time of a cooling agent composed of sodium chloride, potassium chloride and water. The blending ratio is the blending ratio displayed in the upper right column of each graph. In addition, the sample samples were prepared by preparing the cryogens with the blending ratios shown in the table, placing 200 cc in a plastic container, and freezing at −22 ° C. for 48 hours in a freezer to make ice. Yes. Moreover, the sample sample is provided with a hole into which a thermometer can be inserted at the center. The temperature and time are measured by measuring the temperature of a thermometer in which an iced sample sample is inserted into the central hole of the central portion of the sample sample every 0.5 hour (30 minutes) in an environment of room temperature 25 ° C. The reading is measured. Here, the evaluation is performed by expressing the temperature as the cool temperature and the time as the cool time.

  First, the following can be read from FIG. The cold preservation temperature of the cold preservation agent of sodium chloride and water is low at the initial stage. However, when the blending amount exceeds 10% by weight, the cold insulation temperature rises almost linearly, and after 2 hours, the cold insulation temperature reaches 0 ° C or higher. On the other hand, when the blending amount is 5% by weight or 3% by weight, the temperature rise curve after 2 hours becomes smooth, and it takes about 3.0 to 4.0 hours to reach the cold temperature 0 ° C. I understand. It can also be seen that the amount of 3% by weight is longer than 5% by weight. In addition, as the blending ratio of sodium chloride increases, an initial cold temperature is lowered.

  Next, the following can be read from FIG. The cold insulation temperature of the cryogen composed of potassium chloride and water is slightly higher than that of the sodium chloride cryogen at the initial stage. However, the rise in the cold temperature over time is more gradual than in the case of the sodium chloride cold-retaining agent, and shows a gentle gradient as the rising gradient. For this reason, it takes about two hours or more for the cool temperature to reach 0 ° C., and the cool time lasts longer than that of sodium chloride. In addition, the larger the blending ratio, the shorter the cooling time, and the smaller the blending ratio, the longer the cooling time. Also. Also in the case of potassium chloride, the cooling rate is longer when the blending ratio is 3% by weight than when 5% by weight. Further, as the compounding ratio of potassium chloride increases, an initial cold temperature can be obtained.

  Next, in the case of the cold-retaining agent in which sodium chloride and potassium chloride are blended in FIG. 17, it can be seen that the cold-retaining time is slightly increased by mixing sodium chloride and potassium chloride. Moreover, it can be said that the one with less sodium chloride in the blending ratio of sodium chloride and potassium chloride has a longer cooling time. However, since the total amount of sodium chloride and potassium chloride is as high as 17%, the time to reach the cold temperature of 0 ° C is a maximum of 3 hours and is very short.

  Moreover, when there are many compounding quantities of sodium chloride and potassium chloride, when it is made into ice, the crystal grain of ice will become very coarse and will become a rough and rough surface. And ice becomes easy to melt | dissolve, and isolation | separation of a crystal grain will occur in an early time, and it will be in the crunchy sherbet state. In such a state, the cool temperature rises remarkably in a short time. From the results of various tests, it has been found that when the amount of sodium chloride or potassium chloride is 10% by weight or more, such a phenomenon appears remarkably and the cooling time does not last long. On the other hand, when the amount of sodium chloride or potassium chloride is decreased, the ice crystal particles become finer and denser, and the surface state becomes smoother. At the same time, it has been found that the dissolution of the crystal particles becomes slow and the cooling time lasts long.

  Based on the above results, when the cryogen corresponding to the preferred A zone described in Patent Document 1 is evaluated, the blend of sodium chloride and potassium chloride is 15% by weight or more in the A zone cryogen. And, if anything, the amount of sodium chloride is large. From this fact, although it is suitable for producing cryogenic cold insulation of −22 ° C. or lower, the cold keeping time is very short. As can be seen from FIG. 14, after 50 to 60 minutes have elapsed, a rapid increase in the cold insulation temperature is observed, and results similar to the test results described above appear, indicating that the cold insulation time is short. Therefore, it can be said that the A zone cold-retaining agent is not suitable for long-term cooling (for example, 4 hours or 5 hours).

  In addition, in the case where the ice-cooled cryogen containing water and sodium chloride or potassium chloride is sealed in a water-impermeable bag into a cryogen pack, the sodium chloride and potassium chloride content is 15% by weight or more. As described above, the agent dissolves quickly at room temperature and liquefies in the pack. If the pack is torn and a small hole or the like is opened, a liquid cryogen flows out from the pack and adheres to the cold food, thereby impairing the quality of the cold food. In addition, since the water contains a lot of salt, there is a danger that food will be damaged more than water.

  Moreover, in order to create a cryogenic temperature near -30 ° C, an industrial or occupational freezer is required and cannot be produced by an electric refrigerator for general household use.

  The present invention has been made in view of the above problems, and an object of the present invention is to find a cold-retaining agent that can maintain a cold-retaining time for a long time at a cold-retaining temperature of about 0 ° C. or lower. The purpose is to find a cryogen that does not flow out even if it breaks and opens a small hole. Also, find a cold storage agent that is cheap and can be made in a general household refrigerator.

  As a means for achieving the above object, the cold-reserving agent according to claim 1 of the present invention is characterized in that it comprises at least water, a salt, and a superabsorbent polymer component and has a gel-like form. To do.

  Moreover, the characteristics of the cold-retaining agent according to claim 2 of the present invention are such that the blending ratio of water and salt is 95 to 99 parts by weight of water when the total part by weight of water and salt is 100 parts by weight. The salt is a mixture ratio of 1 to 5 parts by weight.

  Moreover, the feature of the cold-retaining agent according to claim 3 of the present invention is that the mixing ratio of the water, the salt and the superabsorbent polymer is 95 to 99 parts by weight of water and 1 to 5 parts by weight of the salt. The superabsorbent polymer has a blending ratio of 2.3 to 4.6 parts by weight with respect to 100 parts by weight of the total of water and salt blended in (1).

  According to a fourth aspect of the present invention, the salt is characterized in that the salt is composed of one or a mixture of sodium chloride, potassium chloride and sodium sulfate.

  The feature of the cold-retaining agent according to claim 5 of the present invention is that the superabsorbent polymer is a sodium polyacrylate having a crosslinked structure.

  In addition, the feature of the cryogen pack according to claim 6 of the present invention is that it is contained in a water-impermeable bag made of a resin sheet or film capable of heat-sealing the cryogen according to any one of claims 1 to 5. It is characterized by being sealed.

According to the present invention, the following effects can be obtained. The cryogen of the present invention comprises at least water, a salt, and a superabsorbent polymer component, and forms a gel form. Sodium chloride (Nacl), potassium chloride (Kcl), or sodium sulfate (Na ₂ SO ₂ .10H ₂ O) is used as the salt. Sodium chloride (Nacl) and potassium chloride (Kcl) are highly effective as a cryogen that lowers the cold temperature, and sodium sulfate (Na ₂ SO ₂ · 10H ₂ O) is highly effective in extending the cold time. . These salts have marketability and can be obtained at low cost. The super absorbent polymer swells by absorbing water, and has the property of gelling or gelling the cryogen. Thereby, even if a hole or the like is opened in the cold pack, the cold pack is prevented from flowing out. In the present invention, the super cooler polymer is blended to gel the cold pack. If it is gel, it has fluidity and flows out depending on the size of the hole, but if it is gel, it loses fluidity and flows out of the hole even if the size of the hole increases. There is nothing. In the present invention, the gel state is defined as a gel-like state having no fluidity and having elasticity, and the gel state is a gel-like state having more water than the gel state and having flexibility and fluidity. It is defined as

  In the present invention, the mixing ratio of water and salt is such that the total weight part of water and salt is 100 parts by weight, the mixing ratio of 95 to 99 parts by weight of water and 1 to 5 parts by weight of salt. To. If the blending ratio of the salt is less than 1 part by weight, the effect of lowering the cooling temperature as a cryogen is small, and if the salt is more than 5 parts by weight, the cooling time does not last long. That is, the time for melting the iced cold-retaining agent is accelerated, and the cold-retaining time is shortened.

  In the present invention, the blending ratio of water, salt, and superabsorbent polymer is 95 to 99 parts by weight of water and 1 to 5 parts by weight of water and salt combined with salt in a blending ratio of 1 to 5 parts by weight. The superabsorbent polymer is used in a proportion of 2.3 to 4.6 parts by weight with respect to 100 parts by weight. When the amount of the superabsorbent polymer is 2.3 to 4.6 parts by weight, a gel-like form is obtained, and even if the cryogen pack is torn and a hole is formed, the cryogen does not come out from the hole. In addition, the cooling time lasts longer.

  As the superabsorbent polymer, sodium polyacrylate having a crosslinked structure is selected as a suitable one. This has a water uptake amount of several tens to several hundred times, and the water absorption in the cross-linked structure is very high, and a large amount of water is absorbed with a small weight. The amount used is small, and it can be cheap in terms of cost.

  Sealing and packaging a non-permeable bag made of a resin sheet or film that can be heat-sealed with a cryogen having the characteristics described above makes it easy to handle and can be used for a wide range of foods. . Further, it can be easily formed even in a refrigerator for general households and can be recycled, so that it can be used for a long period of time, and a cost effect can be obtained.

(First embodiment)
Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. First, the cryogen according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a graph showing the relationship between the cooling time and the cooling temperature of ice composed of water, FIG. 2 is a graph showing the relationship between the cooling time and the cooling temperature of ice composed of sodium sulfate and water, and FIG. FIG. 4 is a graph showing the relationship between the ice keeping time and the ice keeping temperature of ice made of sodium chloride and water, FIG. 4 is a graph showing the relationship between the ice keeping time and the ice keeping temperature of ice made of potassium chloride and water, and FIG. FIG. 6 is a graph showing the relationship between the cooling time and the cooling temperature of ice composed of sodium sulfate, sodium chloride, potassium chloride, and water. FIG. 7 is a table showing the blending amount of the superabsorbent polymer until the cryogen is gelled. FIG. 8 is a graph showing the cooling time and the cooling temperature when the superabsorbent polymer is not blended with the cryogen composed of water and sodium chloride, and FIG. 9 is the cryogen composed of water and potassium chloride. FIG. 10 is a graph showing the cooling time and the cooling temperature when the superabsorbent polymer is not blended and when blended. FIG. 10 shows the case where the superabsorbent polymer is blended with the cryogen composed of water and sodium sulfate. FIG. 11 shows the cooling time and the cooling temperature in the case where the superabsorbent polymer was not blended with the cryogen composed of water, sodium chloride, potassium chloride, and sodium sulfate, and the blending temperature. The graph is shown.

  First, the graph in each figure will be briefly described. Time (h) is taken on the horizontal axis, and is cut every 0.5 hours. Hereinafter, the time on the horizontal axis will be referred to as a cold insulation time. The vertical axis represents temperature. A line graph shows how the temperature changes every 0.5 hours. Hereinafter, the temperature on the vertical axis will be referred to as a cold insulation temperature. The sample used for measurement is a 200 cc capacity refrigerant kept in a plastic container (beaker), frozen in a freezer at −22 ° C. for 48 hours, and made into ice. And the sample sample which became ice in the freezer is taken out, and temperature measurement is performed in room temperature of 25 degreeC. The temperature measurement is taken first from the freezer and is measured soon, and then every 0.5 hours. The measurement is performed by reading the temperature of the thermometer. The thermometer is inserted into a hole provided in the center of the sample sample, and the temperature at the center of the hole is measured.

  The cryogen according to the first embodiment of the present invention is composed of water, a salt, and a superabsorbent polymer component and has a gel-like form. A gel-like state is defined as a gel-like state having no fluidity and elasticity. The water may be tap water, but preferably distilled water or boiling water is used. Distilled water and boiling water are water with few impurities, so freezing gives fine and dense ice with crystal grains, and such ice has a smooth surface and slow melting. And it has the characteristic of keeping the cold insulation time long. As the salt, salts such as sodium sulfate, sodium chloride and potassium chloride are used. Sodium sulfate has the property of delaying the increase in the cold temperature and keeping the cold time longer, and sodium chloride and potassium chloride have the property of lowering the cold temperature. Both are easily available because they are distributed at low cost. The superabsorbent polymer is used for gelling the cryogen. Gels are elastic but not fluid. Therefore, if the gel is completely formed, even if the pack is torn and a hole is formed, the refrigerant does not leak from the hole. As the superabsorbent polymer, sodium polyacrylate having a crosslinked structure is used.

  As shown in FIG. 1, the water-cooled ice has a high cold keeping temperature but a relatively long cold keeping time, and it takes 2-3 hours to reach a temperature from 0 ° to 1 ° at which melting begins. After that, the temperature gradually increases. Since water ice has fine crystal grains and a dense crystal density, it takes a long time to dissolve, and the water after dissolution absorbs heat of vaporization as it evaporates, so the cold temperature does not rise immediately. Therefore, if it does not require cryogenic cooling, water ice can be used as a suitable cryogen.

  The suitable cool temperature varies depending on the food. For example, vegetables and the like are -2, 1 to +4, about 5 ° C, cakes are about -3, 2 to +7, and 8 ° C, and ice cream is about -13 ° C or less. There are a relatively large number of foods in which a cold temperature of around 0 ° C. is suitable among the cold foods, and a cold agent that can maintain this preferred cold temperature as long as possible is most preferable. The cold-reserving agent of the present invention is aimed at a cold-retaining agent that can sustain at least 4 hours at a temperature not higher than the cold-reserving temperature + 3 ° C. by utilizing the above-described characteristics of water.

  Therefore, the cooling agent of the present invention is such that the blending ratio of water and salt is 95 to 99 parts by weight of water and 1 to 5 parts by weight of salt when the total weight part of water and salt is 100 parts by weight. The ratio is set to a suitable range.

From FIG. 2, sodium sulfate (Na ₂ SO ₄ · 10H ₂ O) was mixed with water in an amount of 1.0 part by weight (cooling agent 1), 3 parts by weight (cooling agent 2), and 5 parts by weight (cooling agent 3). In the case of the cold-retaining agent, the cold-retention temperature rises rapidly during the first hour, but after 1 hour, the temperature rise is very low and lasts for 4 hours or more in the range of + 1 ° C or lower. Compared with the water ice of FIG. 1, the cold insulation temperature is lowered by 2 ° to 3 ° and the temperature rise is prevented and the duration of the cold insulation temperature is lengthened. In addition, the refrigerant 2 with 3 parts by weight and the refrigerant 3 with 5 parts by weight have almost overlapping curves. From this, even if the blending ratio is increased, the effect is hardly changed.

  Further, from FIG. 3, a cryogen containing 1 part by weight of sodium chloride (Nacl) (coolant 4), 3 parts by weight (refrigerant 5), 5 parts by weight (refrigerant 6) is the initial cooler temperature. However, the temperature rise is relatively fast, and in the case of the refrigerant 6, it reaches + 3 ° after 4 hours. This is due to the large amount. In addition, the cold-retaining agent 5 containing 3 parts by weight of sodium chloride has the lowest cold-retaining temperature, and the cold-retaining agent 4 containing 1 part by weight appears higher than the cold-retaining agent 5 and lower than the cold-retaining agent 6 as the cold-retaining temperature after 4 hours. From the results of the test, if the blending ratio of sodium chloride is less than 1 part by weight, the effect of lowering the temperature is low, and if kept to 1 part by weight or more and 5 parts by weight or less, the cold holding temperature of + 3 ° C. or less may last for 4 hours. found.

  Also, from FIG. 4, a cryogen containing 1 part by weight of potassium chloride (Kcl) (coolant 7), 3 parts by weight (coolant 8), and 5 parts by weight (coolant 9) is the initial cold temperature. Is higher than that of sodium chloride shown in FIG. 3, but a cooling time of + 1 ° C. or lower is obtained for 4 hours or longer. Also in the case of potassium chloride, the one with 3 parts by weight has the lowest cold insulation temperature, and the cold preservation temperature increases as it increases from 3 parts by weight or as it decreases from 3 parts by weight.

  From the above, when each salt of sodium sulfate, sodium chloride, and potassium chloride is used alone, which salt should be mixed by mixing 95 to 99 parts by weight of water and 1 to 5 parts by weight of salt. Even if it was used, it was possible to obtain a target cold insulation at + 3 ° C. or less for 4 hours.

  Next, FIG. 5 and FIG. 6 explain what happens to the cooling time and the cooling temperature when two or more kinds of salt are mixed. FIG. 5 shows a cooling agent 10 formulated with 2 parts by weight of sodium sulfate, 1 part by weight of sodium chloride and 97 parts by weight of water, and a cryogen 11 formulated with 1 part by weight of sodium sulfate, 2 parts by weight of sodium chloride and 97 parts by weight of water. Shows time and cold temperature. The cold insulation agent 10 shows a rapid temperature rise for the first hour, and thereafter, the temperature rises gently and has a small temperature gradient. On the other hand, the temperature gradient of the cooling agent 11 gradually decreases with time. It can be said that the cold-retaining agent 10 has a strong cold-retaining property of sodium sulfate, and the cold-retaining agent 11 has a strong cold-retaining property of sodium chloride. Thus, it can be seen that when the proportion of sodium sulfate and sodium chloride is large, the cold retention property of sodium sulfate appears strongly, and when the proportion of sodium chloride is large, the cold retention property of sodium chloride appears strongly. In any case, the cold insulation time of 4 hours at a cold insulation temperature of 0 ° C. or less is obtained for both of the cold insulation agents 10 and 11. Moreover, FIG. 6 shows the cooling time and the cooling temperature of the cold-retaining agent 12 blended with 1 part by weight of sodium sulfate, 1 part by weight of sodium chloride, 1 part by weight of potassium chloride, and 97 parts by weight of water. This cold insulating agent 12 also has a cold holding time of 4 hours at a cold holding temperature of 0 ° C. or lower.

  As a result of various tests including the above results, even when each of sodium sulfate, sodium chloride and potassium chloride salts is used alone, or when two or more kinds are mixed, the mixing ratio is 1 to 5 parts by weight. It was found that can be adapted to any salt, and the target can be kept at + 3 ° C or lower for 4 hours.

  Next, the gelation situation when a superabsorbent polymer is blended with the salt described above will be described with reference to FIGS. In the present invention, sodium polyacrylate having a crosslinked structure is suitably selected as the superabsorbent polymer. This cross-linked sodium polyacrylate is granular and has a water uptake of tens to hundreds of times. The water absorption in the cross-linked structure is extremely high, and a large amount of water can be obtained with a small weight. Has the property of absorbing. Commercially available products include Sanyo Chemical Industries, Ltd. trade name: Sunfresh ST-500D.

FIG. 7 shows the blending amount of the superabsorbent polymer until the cryogen is gelled. Here, the criteria for gelation are as follows. When a salt is dissolved in water and a superabsorbent polymer is gradually added thereto, fluid gelation occurs, and when further added, gelation occurs without fluidity. In this test, the degree of gelation was determined to be gelation based on the level at which the sample was deformed by its own weight when the sample was placed on a flat surface at a height of about 5 cm with a bottom area of about 20 cm ² or did not flow. ing. Then, the blending amount of the superabsorbent polymer at the time of the above determination is set as the blending amount until gelation. The highly water-absorbing polymer is made of Sanyo Kasei Kogyo's trade name: Sunfresh ST-500D, a cross-linked sodium polyacrylate.

  In FIG. 7, the class A class is a cryogen containing water and sodium chloride, the class B is a cryogen containing water and potassium chloride, the class C is a cryogen containing water and sodium sulfate, D The thing of the classification has shown the refrigerant | coolant which mix | blended three types, sodium chloride, potassium chloride, and sodium sulfate, with water.

  A cryogen containing sodium chloride of class A is a superabsorbent polymer that becomes gelled as the amount of sodium chloride increases to 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, and 5 parts by weight. Is increased to 2.6 parts by weight, 3.2 parts by weight, 3.7 parts by weight, 4.2 parts by weight, and 4.6 parts by weight. This is the same in the case of potassium chloride of class B and sodium sulfate. In the case of potassium chloride, the superabsorbent polymer increases from 2.3 to 4 parts by weight as the blending amount increases from 1 to 5 parts by weight. In the case of sodium sulfate, the superabsorbent polymer increases from 2.5 parts by weight to 4.5 parts by weight as the blending amount increases from 1 part by weight to 5 parts by weight. This is because when a granular superabsorbent polymer absorbs water and gelates, potassium chloride or sodium chloride is added to the sodium or potassium cation functional group -COONa. The expanded granular polymer is shrunk and the taken-in water is discharged. The more sodium and potassium cations, the more the granular polymer shrinks and more water is expelled. For this reason, it is presumed that the amount of the superabsorbent polymer is increased to absorb the discharged water, gel it again, and further gel it.

  Here, it can be seen from FIG. 7 that there is a characteristic in the blending amount of the superabsorbent polymer. For example, in the case of sodium chloride of class A, in the case of a cryogen of 99 parts by weight of water and 1 part by weight of sodium chloride, the superabsorbent polymer is 2.6 parts by weight, but the amount of water is 98. In the case of a cryogen of 2 parts by weight of sodium chloride and 3.2 parts by weight of superabsorbent polymer, the amount of superabsorbent polymer is 3.2 parts by weight. In the case of 97 parts by weight of water and 3 parts by weight of sodium chloride, the superabsorbent polymer is 3.7 parts by weight of water, 96 parts by weight of water, 4 parts by weight of sodium chloride in the case of a cryogen, 4.2 parts by weight of superabsorbent polymer, 5 parts by weight of sodium chloride in the case of a cryogen Is a blending amount of 4.6 parts by weight of the superabsorbent polymer. Every time sodium chloride is increased by 1 part by weight, the superabsorbent polymer increases at a constant rate of 0.6 to 0.4 parts by weight. This was the same for the B class potassium chloride and the C class sodium sulfate.

  In view of the above, in order to gelate a cold-reserving agent in which 1 to 5 parts by weight of a salt such as sodium chloride, potassium chloride or sodium sulfate is added to water and the total part by weight is 100 parts by weight, 2.3 to It can be seen that 4.6 parts by weight of the superabsorbent polymer may be blended. This is the same even in the case of a cryogen formed by mixing a plurality of these salts.

  In addition, a superabsorbent polymer that is a cross-linked sodium polyacrylate is used to gelate the cooling agent, and the blending amount is 2.3 to 4.6 by reducing the blending ratio of the salt to 1 to 5 parts by weight. It was possible to limit to parts by weight and less parts by weight. Other materials that can be gelled include sodium alginate and sodium carboxymethyl cellulose (CMC). The amount of these materials used is proportional to the amount of water regardless of the amount of salt. For example, it has been found from the test results that about 6 parts by weight of sodium alginate and about 5.5 parts by weight of sodium carboxymethylcellulose are required for gelation with respect to 100 parts by weight of water. It is effective when the amount of salt is large, but in the range where the amount of salt in the present invention is as small as 1 to 5 parts by weight, the superabsorbent polymer can be used in a smaller amount and is economical.

  Next, what happens to the cold insulation time and the cold insulation temperature when a superabsorbent polymer is blended will be described with reference to FIGS. The cryogen that has been gelated by adding the superabsorbent polymer shown in FIGS. 8 to 11 is used in a plastic container (beaker), frozen in a freezer at −22 ° C. for 48 hours, and made into ice. . FIG. 8 shows a composition in which 97 parts by weight of water and 3 parts by weight of sodium chloride are blended with 100 parts by weight of a cryogen, which does not contain a superabsorbent polymer (coolant 5), and 3.7 parts by weight of the superabsorbent polymer. The compounded (cooling agent 13) is shown. Although the curves of the cold-reserving agent 5 and the cold-reserving agent 13 partially show different temperatures in the range of 0.5 ° C., the cold-retaining agent 5 and the cold-retaining agent 13 have almost the same cold-retaining characteristics. It can be said. Further, FIG. 9 shows that the superabsorbent polymer was blended with 100 parts by weight of the cryogen in which 97 parts by weight of water and 3 parts by weight of potassium chloride were blended (the cooler 8), and the superabsorbent polymer was 3.4. A blended part by weight (cooling agent 14) is shown. The curves of the cold insulation agent 8 and the cold insulation agent 14 show that the cold insulation temperatures are partially different within a range of 0.5 ° C, but the cold insulation agent 8 and the cold insulation agent 14 have almost the same cold insulation characteristics. Yes. Similarly, with respect to the sodium sulfate cooling agent shown in FIG. 10, the cooling properties of the cooling agent 2 (which does not contain a highly water-absorbing polymer) and the cooling agent 15 (which contains a highly water-absorbing polymer) are almost the same. Absent. In addition, as for the cold insulation agent mixed with sodium chloride, potassium chloride, and sodium sulfate shown in FIG. 11, the cold insulation characteristics of the one containing the superabsorbent polymer (the cold insulation agent 16) and the one not contained (the cold insulation agent 12) are as follows. It can be said that there is almost no change.

  From the above, even if the super-absorbent polymer is added to make the cryogen into a gel, the cold-retaining characteristics are hardly changed.

  By adding the superabsorbent polymer to the cryogen, the cryogen is gelled, and when it is further added, the gel is gelled. Since the gelled cryogen does not have fluidity, the cryogen does not come out of the hole even if the cryogen pack is torn and a hole is formed. The gelled cryogen having fluidity may leak out from the small holes, but the gelated cryogen will not leak out.

  Moreover, the cold-reserving agent of the present invention has a very large amount of water components and a very small amount of salt components such as sodium chloride, potassium chloride, and sodium sulfate at 1 to 5 parts by weight. For this reason, it was possible to obtain a cooling time of 4 hours or more at a cooling temperature of + 3 ° C. or lower.

  As described above, in the first embodiment, the cryogen that has been gelated by blending water, a salt such as sodium chloride, potassium chloride, or sodium sulfate and a superabsorbent polymer has been described. In order to prevent the generation of mold and the like, it is possible to add a trace amount of a preservative to the gelled cryogen. In particular, when tap water or the like is used, the generation of mold or the like can be prevented by adding a preservative, and recycling can be performed over a long period of time. As the preservative, ethyl paraoxybenzoate, butyl paraoxybenzoate, propyl paraoxybenzoate, isobutyl paraoxybenzoate, isopropyl paraoxybenzoate, and the like can be selected. It is good to mix | blend in 3 weight%. Even if it is added in an amount of more than 0.3% by weight, the antiseptic effect does not change so much, and conversely, it influences the cold insulation temperature and the cold insulation time. On the other hand, if the content is less than 0.05% by weight, the antiseptic effect becomes thin.

(Second Embodiment)
Next, the cryogen according to the second embodiment of the present invention will be described with reference to FIG. In addition, FIG. 12 has shown principal part sectional drawing of the cryogen pack based on 2nd Embodiment of this invention. The cryogen pack of the second embodiment is a pack of the gelled cryogen described in the first embodiment.

  As shown in FIG. 12, the cold pack 20 according to the second embodiment has a structure in which the cold pack 21 is sealed in a water-impermeable bag 24 and covered with a nonwoven fabric 26. The cryogen 21 is blended with the cryogen described in the first embodiment, that is, 95 to 99 parts by weight of water and 1 to 5 parts by weight of at least one salt such as sodium chloride, potassium chloride, and sodium sulfate. Thus, the total amount is 100 parts by weight, and the gelled cryogen obtained by adding 2.3 to 4.6 parts by weight of the superabsorbent polymer in 100 parts by weight. This gelled cryogen has no fluidity but has elasticity like konjac and pudding. Accordingly, since the cryogen pack 20 is a pack of the cryogen 21 having elasticity and no fluidity, the pack shape is not easily collapsed by the degree of being lifted by hand, and the pack is such that it bends. Deformation is just enough. The cryogen pack 20 is used by putting it in ice in a freezer for tens of hours. For example, an iced cryopreservation pack can be obtained by placing it in a freezer of a general household electric refrigerator and freezing it at a temperature of about −22 ° C. for about 24 to 48 hours.

  A non-woven fabric 26 is provided on the surface (upper surface and lower surface) of the water-impermeable bag 24, and the non-woven fabric 26 absorbs water droplets formed by cooling the surrounding air by cooling. In other words, it plays a role as a dew condensation preventing agent, and works to prevent the quality of the cold food from deteriorating due to dew condensation. Further, the water-impermeable bag 24 is composed of a two-layer film in which two films of a lower film 22 and an upper film 23 are stacked.

  Here, the lower film 22 and the upper film 23 of the water-impermeable bag 24 are made of a resin sheet or film that is not water-permeable and can be heat-sealed. Examples of such films include polyethylene, polyvinyl chloride, nylon, and polyethylene terephthalate. Such as sheets and films. The lower layer film 22 and the upper layer film 23 may be made of the same material or different materials. In the case where different materials are used, it is preferable to select a material that is strong in strength for the upper layer film 23. The thickness of the lower layer film 22 and the upper layer film 23 is preferably in the range of 40 to 90 μm, and the non-water-permeable bag 24 is formed by bonding the lower layer film 22 and the upper layer film 23 by heat fusion. When a heat-sealable resin sheet is used, a two-layer structure or a bag can be easily formed by a heat sealing method, and the manufacturing cost can be reduced. Further, by stacking two sheets, the strength is increased and an impact resistance effect is obtained. In addition, the water-impermeable bag 24 is not necessarily limited to a two-sheet configuration, and a single-sheet configuration can also be used because the cryogen 21 is gelled and the nonwoven fabric 26 is provided. Since the cold insulating agent 21 is gelled, even if the non-permeable bag 24 is torn and a small hole is opened, it does not leak outside, and there is almost no risk of wetting the cold stored food.

  Since the cryogen pack 20 having the above-described configuration does not use a high member, it can be reduced in cost and can be easily iced in a general home freezer. Moreover, since the cold-reserving agent 21 is formed using a commercially available material, it can be made in a general household. Also, how to make it is not difficult. Further, since it can be recycled, it can be used for a long time.

  Such a cold pack 20 can be widely used for cold foods, for example, cold storage of vegetables and fruits, cold storage of fish and meat, cold storage of cooked sashimi, cold storage of cakes, cold storage of ice cream. , And so on. It is better to set the size and thickness of the pack according to the application.

  It is the graph which showed the relationship between the cool time of the ice which consists of water, and cool temperature.   It is the graph which showed the relationship between the cooling time and the cooling temperature of the ice of the composition which consists of sodium sulfate and water.   It is the graph which showed the relationship between the cold preservation time of the ice consisting of sodium chloride and water, and the cold preservation temperature.   It is the graph which showed the relationship between the cooling time of ice consisting of potassium chloride and water, and the cooling temperature.   It is the graph which showed the relationship between the cold preservation time of the ice which consists of sodium sulfate, sodium chloride, and water, and cold preservation temperature.   It is the graph which showed the relationship between the cool time and the cool temperature of the ice which consists of sodium sulfate, sodium chloride, potassium chloride, and water.   It is the table | surface which showed the compounding quantity of the superabsorbent polymer until a cooling agent gelatinizes.   It is a graph which shows the cold preservation time and cold preservation temperature at the time of mix | blending the case where a superabsorbent polymer is not mix | blended with the cryogen which consists of water and sodium chloride.   It is a graph which shows the cool time and cool temperature at the time of mix | blending the case where a superabsorbent polymer is not mix | blended with the cryogen which consists of water and potassium chloride.   It is a graph which shows the cool time and cool temperature at the time of mix | blending the case where a superabsorbent polymer is not mix | blended with the cryogen which consists of water and sodium sulfate.   It is a graph which shows the cool time and the cool temperature at the time of mix | blending the case where a superabsorbent polymer is not mix | blended with the cryogen which consists of water, sodium chloride, potassium chloride, and sodium sulfate.   The principal part sectional drawing of the cryogen pack which concerns on 2nd Embodiment of this invention is shown.   It is the figure which showed the relationship between the cold storage time of -26--22 degreeC as described in patent document 1, and the compounding quantity of sodium chloride and potassium chloride.   It is the graph which showed the relationship between the temperature change of a refrigerant | coolant which was shown by patent document 1, and elapsed time.   It is the graph which showed the temperature and the relationship of time of the cryogen comprised with sodium chloride and water.   It is the graph which showed the relationship between the temperature and time of the cryogen comprised with potassium chloride and water.   It is the graph which showed the relationship between the temperature and time of the cryogen comprised with sodium chloride, potassium chloride, and water.

Explanation of symbols

20 Coolant Pack 21 Coolant 22 Lower Layer 23 Upper Layer 24 Non-Water-permeable Bag 26 Nonwoven

Claims (6)

  A cold-retaining agent comprising at least components of water, a salt, and a superabsorbent polymer and having a gel-like form.   The blending ratio of the water and the salt is characterized in that when the total weight part of the water and the salt is 100 parts by weight, the blending ratio is 95 to 99 parts by weight of water and 1 to 5 parts by weight of the salt. The cryogen according to claim 1.   The blending ratio of the water, the salt and the superabsorbent polymer is high with respect to a total of 100 parts by weight of water and salt in which 95 to 99 parts by weight of water and 1 to 5 parts by weight of salt are blended. The cold-retaining agent according to claim 1 or 2, wherein the water-absorbing polymer is 2.3 to 4.6 parts by weight.   4. The cryogen according to any one of claims 1 to 3, wherein the salt comprises one or a mixture of sodium chloride, potassium chloride, and sodium sulfate.   The cold-retaining agent according to any one of claims 1 to 3, wherein the superabsorbent polymer is a sodium polyacrylate having a crosslinked structure.   A cryogen pack, wherein the cryogen according to any one of claims 1 to 5 is sealed in a water-impermeable bag made of a resin sheet or film that can be heat-sealed.

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