JPH05117641A - Production of cold reserving material - Google Patents

Abstract

PURPOSE:To produce the title material which has a freely controllable water content and a large cold-reserving capacity and is flexible even at a temp. of refrigeration room and suitable for cooling a human body, etc., by mixing a highly water-absorbing resin with water and then with a water-insol. solvent contg. a surfactant. CONSTITUTION:The title material is produced by mixing 100 pts.wt. highly water-absorbing resin with 100-50,000 pts.wt. water and then with 10-300 pts.wt. water-insol. solvent contg. a surfactant in an amt. of 0.01-20 pts.wt. based on 100 pts.wt. water. Such two-step mixing enables the water content of the material to be freely controlled and gives rise to a cold reserving material which has a large cold-reserving capacity, is flexible even at-18 deg.C, and is suitable for cooling a human body, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing a cold insulating material used as a heat medium for cold storage in the field of health industry using foods, human body cooling tools and the like.

[0002]

2. Description of the Related Art Conventionally, ice is the most popular cold insulator, and ice has been used to keep food such as fresh fish and meat for a long time. It was Ice stores a large amount of heat, but when it comes into direct contact with the human body, such as an ice cube or a water pillow, the hardness of the ice makes the human body uncomfortable, and therefore a substitute is required. As such an alternative cold insulating material, an invention using an aqueous solution of polyhydric alcohol or the like has recently been proposed (JP-A-56-40138). Since the polyhydric alcohol aqueous solution and the like are antifreeze and have a good feeling in use, there is a problem that the heat storage amount is small. As a solution to this, many cold-insulating materials have been proposed which are devised so as to retain flexibility even when water freezes. Of these, a hydrogel containing water in a superabsorbent resin is often used, and as a form of use, the superabsorbent resin is sandwiched between flexible substrates (Japanese Patent Laid-Open No. 61-59171).
No. 55-118991) Kneading into a rubber-like substance (JP-A No. 62-283119, JP-A No. 62-283119)
267386) Packing of gel-like substance (JP-A-57-57)
No. 150769).

[0003]

However, in the above-mentioned method, the temperature of the freezer of the domestic refrigerator is -1.
Insufficient flexibility after cooling to 8 ° C limits its use. The above-mentioned method has the best flexibility after cooling, but in the cold insulating material described in JP-A-57-150769, a super absorbent resin is simply added to an emulsion of water and oil, and the mixture is simply mixed. High-speed stirring for the purpose of maintaining an emulsion state is necessary, and the superabsorbent resin needs to be added gradually, which requires a long time for addition. Further, there is a problem that the cold insulating material made by the poor contact between the highly water-absorbent resin and water becomes rough and uncomfortable during use. Further, it is also described that a highly water-absorbent resin preliminarily absorbed and swollen with water can be prepared by mixing and dispersing it in a water-insoluble solvent containing a surfactant, but in the invention, stirring is not kneading. However, there is a problem that the mixing does not work well.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method of manufacturing a cold insulating material which has a large cold insulating capacity and has a good usability when cooling a human body or the like.

[0005]

Means for Solving the Problems The present invention, which has achieved the above object, refers to a method for producing a cold insulating material comprising a water-insoluble solvent, water and a superabsorbent resin, and 100 parts by weight of water to 100 parts by weight of superabsorbent resin. After adding ~ 50000 parts by weight and kneading, 10 to 300 parts by weight of a water-insoluble solvent containing 0.01 to 20% by weight of a surfactant is added to 100 parts by weight of water, and further kneading. It is what

[0006]

The superabsorbent resin used in the present invention has 1 to 1 of its own weight.
There is no limitation as long as it absorbs 1,000 times more water, and partially crosslinked polyacrylic acid neutralized product, neutralized product of starch-acrylonitrile graft polymer, neutralized product of starch-acrylic acid graft polymer, vinyl acetate- Saponified Acrylic Ester Copolymer, Saponified Acrylonitrile Copolymer, Hydrolyzate of Acrylonitrile Copolymer or Acrylamide Copolymer, or Crosslinked Products of These, Polyvinyl Alcohol, Self-Crosslinking Sodium Polyacrylate, Maleic Acid Any one of -α-olefin copolymer, polymer compound having sulfonic acid group, etc. can be used, but among them, polyacrylic acid partially neutralized product crosslinked product, starch-acrylic acid graft polymer neutralized product, self-crosslinking type The water absorption capacity of sodium polyacrylate and polymer compounds having sulfonic acid groups Et al preferred. The shape of the super absorbent polymer is not particularly limited, and any of granular, fine powder, spherical and the like can be used.

The kneading in the present invention means a state in which the raw materials are mixed and kneaded, and a kneader such as a kneader, a pug mill, a Banbury mixer or a static mixer is required to achieve the object. It is most preferable to use a kneader. Stirring devices such as vertical stirrers and high-speed portable stirrers have weak stirring power, and are not suitable for kneading super absorbent resin gels whose viscosity has been increased by water absorption during mixing, and are suitable for the production of the cold insulating material of the present invention. Is not suitable. The order of addition of each substance in the present invention is specified as the one in which water is added to the superabsorbent polymer and then the water-insoluble solvent is added, and the other order of addition is excluded for the following reasons.

When the water-insoluble solvent is put in the kneader first and the water-absorbent resin and water are added separately, the water-absorption rate of the water-absorbent resin is slow and it takes a long time to prepare a uniform composition. In order to put the water-insoluble solvent in the kneader first and add the mixture of the superabsorbent resin and water, another stirring device is required,
It is uneconomical and it is difficult for a highly water-absorbent resin that absorbs water to form a block and form a uniform composition. The present inventor studied the mixing ratio of the water-insoluble solvent, water and the super absorbent polymer to obtain a cold insulating material having good flexibility. 10
0 to 50000 parts by weight, and further to 100 parts by weight of water,
Water-insoluble solvent containing 0.01 to 20% by weight of surfactant 1
It was found that 0 to 300 parts by weight is preferable. If the amount of water to be added is out of the above range, the resulting cold insulating material will lack flexibility, and if the amount of the surfactant added is insufficient, the cold insulating material cannot be given sufficient flexibility. On the contrary, if the amount is too large, it becomes impossible to secure a sufficient cold storage time.

[0009]

The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited to these examples. Moreover, the part in an Example represents a weight part. Example 1 100 parts of a crosslinked polyacrylic acid partially neutralized product (Aqualic CA, manufactured by Nippon Shokubai Co., Ltd.) as a highly water-absorbent resin was kneaded with 1000 parts of water using a kneader, and the resulting mixture was surface-active. Agent: Add a mixture of 25 parts of sorbitan monooleate (SPAN80, manufactured by Kao Corporation) and 500 parts of water-insoluble solvent: liquid paraffin (manufactured by Wako Pure Chemical Industries, Ltd.), knead these with a kneader, and mix into sleet A cold insulation material was obtained. Of the obtained cold insulating material, 150 g was put in a polyethylene bag to prepare a cold insulating material. The bag-filled cold insulating material thus obtained is cooled to -18 ° C, the surface flexibility at that time, and the time from the standing at room temperature (20 ° C) until the surface temperature reaches 10 ° C (cooling time Called). The results are shown in Table 1.

Comparative Example 1 Superabsorbent resin: 100 parts of polyacrylic acid partially neutralized crosslinked product (Aquaric CA, manufactured by Nippon Shokubai Co., Ltd.) and 100 parts of water
Attempting to stir 0 part with a three-one motor, but could not stir well because of high viscosity. To the obtained mixture, a surfactant; sorbitan monooleate (SPAN)
A mixture of 80 parts, 80 parts, manufactured by Kao Corporation) and 500 parts of a water-insoluble solvent; liquid paraffin (manufactured by Wako Pure Chemical Industries, Ltd.) was added, but it was a non-uniform slurry. 150 g of the obtained cold insulating material was put in a polyethylene bag and used as a comparative cold insulating material. The bag-shaped cold insulating material thus obtained was used in Example 1.
In the same manner as above, the flexibility and cooling time when cooled to −18 ° C. were measured, and the results are shown in Table 1.

Comparative Example 2 Surfactant; sorbitan monooleate (SPAN8)
0, manufactured by Kao Co., Ltd.) and a water-insoluble solvent; 500 parts of liquid paraffin (manufactured by Wako Pure Chemical Industries, Ltd.) were kneaded with a kneader, and a highly water-absorbent resin separately prepared; polyacrylic acid A mixture of 100 parts of partially neutralized crosslinked product (Aquaric CA, manufactured by Nippon Shokubai Co., Ltd.) and 1000 parts of water was mixed,
The gel remained uneven. 1 of the obtained cold insulating materials
50 g was put in a polyethylene bag and used as a comparative cold insulator. The bag-filled cold insulation material thus obtained was measured for flexibility and cold insulation time when cooled to −18 ° C. in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 3 Water-insoluble solvent; liquid paraffin (Wako Pure Chemical Industries, Ltd.)
1000 parts) and a surfactant; sorbitan monooleate (SPAN80, manufactured by Kao Co., Ltd.) 50 parts, and then mixed.
An emulsion could be formed by high-speed stirring using a homomixer while adding 1000 parts of water. In the emulsion thus obtained, a highly water-absorbent resin; partially crosslinked polyacrylic acid neutralized product (Aquaric CA, manufactured by Nippon Shokubai Co., Ltd.)
Although 100 parts was added, it became mamako partially and a uniform slurry was not obtained. 150 of the obtained cold insulating materials
g was put in a polyethylene bag to make a comparative cold insulator. The bag-filled cold insulation material thus obtained was measured for flexibility and cold insulation time when cooled to −18 ° C. in the same manner as in Example 1, and the results are shown in Table 1.

Example 2 Superabsorbent resin: 100 parts of polyacrylic acid partially neutralized crosslinked product (Aquaric CA, manufactured by Nippon Shokubai Co., Ltd.) and 100 parts of water
00 parts were kneaded with a kneader. Separately surfactant; sorbitan monostearate (SPAN60, Kao Corporation)
(Manufactured by Wako Pure Chemical Industries, Ltd.) and 250 parts by weight of water-inert solvent; Both mixtures were kneaded with a kneader to obtain a cold insulating material. 150 g of the obtained cold insulating material was put in a polyethylene bag to obtain a cold insulating material. In the same manner as in Example 1, the bag-filled cold insulation material thus obtained was measured for flexibility and cold insulation time when cooled to −18 ° C., and the results are shown in Table 1.

In Examples 3 to 12 and Comparative Examples 4 to 10, the type of superabsorbent resin, the amount of water used, the type and amount of the water-insoluble solvent and the surfactant in Example 1 were changed. Other than that, the same operation as in Example 1 was repeated to obtain a cold insulating material and a bag cold insulating material. The bag-filled cold insulation material thus obtained was measured for flexibility and cold insulation time when cooled to -18 ° C in the same manner as in Example 1, and the results are shown in Table 1.

[0015]

[Table 1]

Super absorbent polymer: Cross-linked polyacrylic acid partially neutralized product [trade name: manufactured by AQUALIC CA Co., Ltd. Nippon Shokubai]: commercial product of polymer compound containing sulfonic acid group: starch-acrylic acid graft weight Combined neutralized product [Product name: Sunwet Sanyo Chemical Co., Ltd.] Water-insoluble solvent Liquid paraffin (Wako Pure Chemical Industries, Ltd.) Silicon oil (Toshiba Silicon Co., Ltd.) Seed oil (Nisshin Oil Co., Ltd. ) Surfactant Sorbitan monostearate (SPAN60, manufactured by Kao Corporation) Sorbitan monooleate (SPAN80, Kao Corporation)
Made) Flexibility evaluation at -18 ° C cooling ◎: Particularly soft ○: Soft △: Slightly hard ×: Hard

Each of the bag-filled cold insulating materials obtained in Examples 1 to 12 was subjected to a test in which cooling (-18 ° C.) and room temperature standing (20 ° C.) were repeated alternately 100 times. As a result, no change in cold storage performance and flexibility was observed. As is clear from Table 1, in Comparative Examples 1 to 10, since the flexibility evaluations at the time of cooling at -18 ° C are all hard, they give discomfort during use. In particular, Comparative Example 1 using a three-one motor as a mixing device and Comparative Example 3 using a homomixer have problems only in mixing. On the other hand, in each of Examples 1 to 12, the flexibility evaluation at the time of cooling at -18 ° C is good and soft.

[0018]

EFFECTS OF THE INVENTION Since the present invention is constituted as described above, the content of water can be freely controlled, particularly the amount of heat storage is large and it has flexibility when cooled to -18 ° C.
It has become possible to provide a manufacturing method of a cold insulating material which is good for cooling a human body and the like.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadao Shimomura 5-8 Nishimitabicho, Suita City, Osaka Pref.

Claims (1)

[Claims] 1. A method for producing a cold insulating material comprising a water-insoluble solvent, water and a superabsorbent resin, wherein 100 to 50000 parts by weight of water is added to 100 parts by weight of the superabsorbent resin, and the mixture is kneaded. 0.01 to 2 parts by weight of the surfactant with respect to parts by weight
A process for producing a cold insulating material, comprising adding 10 to 300 parts by weight of a water-insoluble solvent containing 0% by weight and further kneading.