JPS5837076A - Production of heat insulating gel - Google Patents

Abstract

PURPOSE:To form a heat insulating gel which is highly elastic and has a touch similar to that of the living tissure, by dissolving an antifreezing agent in an aq. soln. of polyvinyl alcohol, cooling the soln. and deaerating it under vacuum. CONSTITUTION:An aq. soln. or suspension contg. 2.5-10wt% polyvinyl alcohol having a saponification degree of 95mol% or above and a viscosity-average MW of 1,500 or above and 20-80wt. water-soluble org. compd. (antifreezing agent such as ethylene glycol or propylene glycol) is prepd, poured into a container in a required shape, cooled to -6 deg.C or lower, kept at this temp. for an hour or longer, and vacuum-dried (dehydration degree of 60wt% or below) at 10mm.Hg to form a heat insulating gel. The resulting gel is suitable for use as an ice pillow substitute or an ice bag substitute, and is not frozen (not stiffened) even when it is cooled in a freezer of a household refrigerator.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a cold-retaining gel, and particularly provides a method for producing a cold-retaining gel made from polyvinyl alcohol and having excellent properties not seen in conventional cold-retaining gels.

Various cooling gels have already been proposed, with names such as cooling gel, cold preservation gel, heat medium for cold preservation, colloidal refrigerant, cold preservation equipment, cold preservation composition, or ice pillow that does not require ice, and some of them have been put into practical use. It is served to. However, the following (1) to (
As summarized in 9), all of them have problems in product properties or manufacturing methods.

(1) The production of agar gel is well-known as an easy method for producing hydrogel for cold storage. That is, to hot water or boiling water at 80 to 94°C, Q, 1 wt% or more, for example 1 to 10
After dissolving agar equivalent to wt%, a water-containing gel (hydrogel) having a water content of about 90 to 99 wt% can be easily obtained by allowing it to cool to room temperature. However, when this gel is cooled in the ice compartment of a refrigerator and then used as a cold-preserving gel, such as an ice pillow or an ice bag substitute, the gel balls have poor elasticity and are extremely brittle, so foreign substances may come into contact with the human body. Moreover, the gel disintegrates during use, which is far from providing a comfortable feeling.

In addition, it often freezes and hardens in the ice compartment of a refrigerator, making it inconvenient to use as a substitute for ice pillows or ice bags. In this case, the freezing temperature can be lowered by immersing agar in an antifreeze solution such as ethylene glycol or propylene glycol, or by cooling a heated aqueous solution containing both agar and antifreeze solution. The gel is also brittle and easily disintegrates, making it unsuitable for use in pillows and other cold storage gels.

(D-galactose type structure similar to 21 agar, 3゜6-
Similar to agar, monocarrageenan, which contains an anhydrogalactose type structure and a polygalactose partially corroded type structure, can easily form a hydrogel (with a water content of 90 to 90%).
(approx. 7 wt%) 1-Although it has the disadvantage of being brittle like agar, it is also extremely soft. It has been often emphasized for a long time that the mechanical strength of this gel can be increased by soaking it in an aqueous solution of potassium chloride or calcium chloride, but even after such post-treatment, it is still brittle like agar. remains unchanged.

It is well known that carrageenan is used in combination with locust bean gum to increase the elasticity of the gel, but it is not very effective.

In addition, the fact that it freezes and hardens in the refrigerator icebox and the problems after countermeasures with antifreeze such as ethylene glycol are the same as in the case of agar.

(3) From an aqueous solution of a sodium salt of alginic acid containing a D-manuronic acid type structure and an L-guluronic acid type structure, it can be converted into an acidic aqueous solution (pH 2.5 to 5), or calcium, barium, zinc, copper, etc. By dropping (or immersing) in an aqueous solution containing water-soluble salts such as iron, aluminum, nickel, etc., a hydrogel with a water content of 97 to 98 wt% can be obtained, but this gel is also easily crushed, brittle, and agar-based. As in the case of , it freezes and becomes rigid.

(4) Gelatin gel is also known, but at a gelatin concentration of 2 to 15 wt%, it only takes on a soft jelly-like appearance;
Although a strong gel can be obtained by increasing the gelatin concentration to 15 wt% or more, especially 30 wt% or more, it is a rigid gel that lacks flexibility, has a low water content, and has the disadvantage of emitting a glue odor.

(5) Konnyaku, which contains a D-mannose type structure and a D-glucose type structure, has many natural product gels (gelatin,
Tofu, starch starch paste, agar, alginic acid, curdlan, carrageenan, farselan, bekte/), it is particularly hard to lose its shape, has flexibility and elasticity, and has a water content of up to 97wt. It's a gel. However, when used repeatedly as a cold storage gel, the gel rapidly disintegrates. In other words, konnyaku is relatively stable as it is soaked in an alkaline cold water solution containing cal/lam ions, but what about this? During the process of repeated freezing and thawing, precipitation and uneven distribution of lime are promoted, and the gel becomes pasty.

(61CMC (carboxymethylcellulose = sodium cellulose glycolate) iron, chromium.

Aluminum, lead, barium, and tin salts were also proposed;
It is a soft pasty gel, and the gel structure often disintegrates (Japanese Patent Publication No. 45-11210). Starch or CMC and Borax (Sodium Tetraborate Decahydrate)
The gel produced by the reaction with is also famous, but it is also weak.

Furthermore, even if antifreeze is used as a countermeasure against freezing and hardening, the gel still disintegrates.

(7) It has been well known for a long time that when boric acid (or boric acid aqueous solution) or borax (or borax aqueous solution) is added to an aqueous polyvinyl alcohol solution, gelation occurs immediately. However, the resulting gel is fluid, soft, and readily breaks into pieces by simply pinching it with the fingertips. In addition, there is a problem of syneresis (separation of water contained) during repeated use (Japanese Patent Publication No. 45-11210).

Store polyvinyl alcohol/porous sand gel in the refrigerator (freezer)
When cooling in an ice chamber, the water inside the gel freezes.In order to avoid the gel from becoming hard, monohydric alcohol, polyhydric alcohol, glucose, or sucrose is added to the polyvinyl alcohol aqueous solution, and then the water inside the gel freezes. A method of forming a gel with sand has also been proposed, but in this case, the strength of the gel is rather reduced, and there is also the problem that syneresis occurs during repeated use (Japanese Patent Publication No. 19602/1973).

Another method for lowering the freezing point of polyvinyl alcohol-porous sand gel is to immerse the gel in an antifreeze solution such as ethylene glycol or propylene glycol. In addition to further weakening and losing its shape,
Antifreeze solutions such as methanol, ethanol, and acetone also have the disadvantage that the gel collapses.

(8) Many methods have been proposed for gelling polyvinyl alcohol using phenols or amino compounds such as phenol, naphthol, and Congo red, or metal compounds such as titanium, chromium, and zirconium.
Both have the same drawbacks as the polyvinyl alcohol/borax gel described above.

(9) Aldehydes, dialdehydes, unsaturated nitriles.

Diisocyanate, trimethylolmelamine.

Shrimp chlorohydrin, bis-(β-hydroquinethyl)
Gelation of polyvinyl alcohol using cross-linking agents or copolymer components such as sulfone, polyacrylic acid, dimethylol urea, and maleic anhydride is also well known, but all of these methods require operations using chemical reagents and do not harden in refrigerators (freezers) or ice chambers. In order to obtain a gel that is difficult to wash, the gel must be immersed in an antifreeze solution such as ethylene glycol for a long time, and it is difficult to obtain a gel that is highly elastic and flexible.

The present inventor has conducted studies to develop a method for inexpensively and stably producing a gel using polyvinyl alcohol, which is water-insoluble, has excellent mechanical properties, and is difficult to freeze in refrigerators (freezers) and ice chambers. By cooling, solidifying, or cooling, solidifying, and vacuum dehydrating (drying) an aqueous solution or suspended aqueous solution containing both polyvinyl alcohol and a water-soluble organic compound, a solid gel with high elasticity and flexibility that is resistant to freezing is produced. We have obtained the knowledge that this can be obtained, and hereby we have completed the present invention, which has a remarkable effect.

That is, the present invention contains polyvinyl alcohol with a saponification degree of 95 molt or more and a viscosity average polymerization degree of 1, 5' (), 0 or more, and a water-soluble organic compound, and the concentration of the polyvinyl alcohol is 2.5 to 10 wt%. An aqueous solution or suspended aqueous solution of the organic compound whose concentration is adjusted to 20 to 8 Qwt% is poured into a container of any shape, and then cooled to a temperature lower than -6°C. Be sure to perform the vacuum drying process below! To provide a method for producing a cold storage gel having the following characteristics.

According to the present invention, by gelling an aqueous solution or M turbid aqueous solution containing both polyvinyl alcohol and a water-soluble organic compound, a gel that is highly elastic and flexible and does not freeze even in a freezer icebox can be obtained. The present invention uses acid, alkali, and radical sources, which are conventionally used in the gelation of synthetic polymers, in the gelation process and in the pretreatment process.

Secondary curing treatment or freezing point (temperature) without the need for radiation, organic bath medium 1 reaction reagent, etc.? f: No post-processing is required to reduce f. Moreover, the gel obtained by the present invention also has rubber-like elasticity, flexibility, and mechanical strength necessary for a soft type (non-freezing hardening) gel for cold storage.

Polyvinyl alcohol aqueous solution at 0-30℃ 11j-1
It has been well known for a long time that gelation often occurs when stored for about a week, but this gel is brittle like agar, and when used as an alternative to ice pillows, for example, the gel structure collapses, and the ice cell in the freezer Freezes and hardens easily. On the other hand, the gel of the present invention has elasticity, flexibility, and strength suitable for use as an ice pillow substitute, and does not freeze or harden even in a freezer ice compartment, retaining its original elasticity, flexibility, and strength. This means that the present invention provides a cold-retaining gel that is completely different from conventional simple polyvinyl alcohol gels.

The degree of saponification of polyvinyl alcohol used in the present invention is 9
It requires 5 molti or more, preferably 97 molti or more. Even if polyvinyl alcohol having a saponification degree of 80 to 88 mol, especially less than 85 mol, is used, only a weak gel is obtained, and the object of the present invention cannot be achieved.

The degree of polymerization of the polyvinyl alcohol used in the present invention is 1,
Requires 500 or more. Otherwise, only a soft gel will be produced, and in the present invention, for example, the degree of polymerization is 1.50.
Polyvinyl alcohol with a polymerization degree of about 0 to 3,300 can be used, but commercially available polyvinyl alcohol with a polymerization degree of 1,50 or so can be used.
0 to 2,600) is preferably used as is.

In the present invention, first, an aqueous solution or suspension aqueous solution containing both polyvinyl alcohol and a water-bathable organic compound is prepared. The concentration of polyvinyl alcohol is 2.5 to 1.
It can be 0 wt%, preferably 3 to 8 wt%. If the concentration is higher than this 'ilQwt%, it is not preferable because a gel that is too hard to be used as an ice pillow replacement cold gel tends to be produced.

In addition, if this concentration is lowered to 2.5 wt%, it will be too soft to be used as an ice pillow substitute, and the gel molded product will lose its shape and collapse.
It is not a good trench because it is easy to get caught.

The present invention is characterized in that, prior to forming the gel, a water-soluble organic compound as an antifreeze agent (freezing point depressant) is dissolved in the polyvinyl alcohol aqueous solution.

An example of this antifreeze agent is ethylene glycol. The freezing point of pure ethylene glycol is -16°C, but the concentration of pure ethylene glycol is 38vol 1% and 58vol 1% (60w
The freezing point of an aqueous solution of t%) is -23°C and -49°C, respectively.
Therefore, it is not necessarily necessary to coexist a particularly large amount of ethylene glycol, for example, 58 vol%, in the polyvinyl alcohol water bath solution. By lowering the freezing point to about -20°C, the object of the present invention can be achieved. This antifreeze effect is not limited to ethylene glycol, but also propylene glycol (40% substitution, -20℃), 1゜3-propylene glycol (5Qwt% substitution, -24℃), glycerin (49% substitution, -24℃),
wt% substitution, -21°C).

It is also found in water-soluble polyhydric alcohols such as 2-methyl-2,4-bentanediol (71 wt presubstituted, -20°C), which lower the curing temperature of the gel to below -20°C, making it less difficult to use for normal household use. Ice chamber of refrigerator (freezer) (-1O to -2
At 0°C), it does not usually harden and retains its flexibility and feel similar to living tissue, making it suitable for applications such as ice pillows.

These polyhydric alcohols, in addition to the above-mentioned action as a freezing point depressant, also contribute to improving the mechanical strength of the cold-retaining gel obtained by the present invention. In other words, simple polyvinyl alcohol water-soluble/i! Compared to the case where woge/l= becomes
The coexistence of the above-mentioned polyhydric alcohol brings about a significant improvement in gel strength, and therefore, even from a low concentration aqueous solution of polyvinyl alcohol, such as a 2.5-8 wt% aqueous solution, which normally produces only an extremely soft gel, the above-mentioned The coexistence of polyhydric alcohol makes it possible to obtain a cold-retaining gel with mechanical strength suitable for use as an ice pillow substitute.

The coexisting concentration of polyhydric alcohol is 20 to 8 wt%.
, preferably 35 to 75 wt%. When this coexisting concentration is 2Qwt% or less, gel freezing and
The curing point is lowered to -1o phosphorescence, and the mechanical strength of the gel is also significantly lowered. If the coexistence concentration is 80w7% or higher, the freezing point may be lowered by an unnecessary amount, and the freezing/hardening point may even increase.In any case, it is unnecessarily economical. increase the burden. The freezing and hardening temperature lowering effect of the gel was determined by methyl alcohol (25wt% substitution, freezing point -20℃), ethyl alcohol (3Qwt% substitution, -20℃), isopropyl alcohol (40wt% substitution, -19℃), and ethyl alcohol. Alcohol (40-wt% substitution, -21°C), ethoxyisopropyl alcohol (62-wt% substitution).

It is also found in water-soluble monohydric alcohols such as -30°C) or their derivatives, as well as acetone (36wt% substitution, -20°C).
°C), dimethyl sulfoxide (37 wt% ffi conversion, -
25°C), methylsulfonic acid (32wt% tfim, -
28°C), ethylsulfone [1 (37 wt% > -2
4℃) Furthermore, dimethylamine (33 wt%!, -
20°C), methyl amine:/(20wt% substitution, -20°C
) is commonly found in water-soluble organic compounds such as Gym (35 wt% substitution, -20°C), which achieves the objective of lowering the freezing point with the advantage of being odorless, with very little volatility, and with a relatively small amount of substitution. Ethylene glycol and propylene glycol are particularly preferred in consideration of their contribution to scale and further to the mechanical strength of the resulting gel. Trinotylene glycol (1,3-propylene glycol) and 2,4-bentanediol are inferior to the above-mentioned ethylene glycol and propylene glycol in that they emit a faint almond-like odor, while 1,3-butanediol and glycerin are In terms of economy, it is still inferior to ethylene glycol and fluoropylene gellicol.

To prepare an aqueous solution or suspended aqueous solution containing both polyvinyl alcohol and a water-soluble organic compound as an antifreeze agent, add, dissolve, and suspend the polyvinyl alcohol and the water-soluble organic compound in water. In addition to the cloudy method, by dissolving hepolyvinyl alcohol in water in advance,
Thereafter, this is mixed with the water-soluble organic compound (or its aqueous solution), or the water-soluble organic compound (''
or its aqueous solution) by adding, dissolving, or suspending a polyvinyl alcohol aqueous solution or polyvinyl alcohol powder; in either method,
Finally, polyvinyl alcohol concentration 2.5~lQwt
%, and the concentration of the water-soluble organic compound is adjusted to 20 to 8 Qwt%. In these cases, since polyvinyl alcohol is sparingly soluble in solvents other than water, it often takes a state in which transparent microgel particles are dispersed in an aqueous solution of a water-soluble organic compound (transparent suspended aqueous solution state). There is no problem in carrying out the present invention.

In the present invention, an aqueous solution or suspended aqueous solution containing the above polyvinyl alcohol and a water-soluble organic compound is poured into a container of any shape or a desired molding mold, and is cooled and molded.

In this case, the coolant may be, for example, salt-ice (23 nia 7 ) (-21°C), calcium chloride-ice (30 nia 0) (-55°C), or dry ice-methyl alcohol (- 72℃), liquid nitrogen (-19
6°C) to a temperature lower than -6°C. Furthermore, if liquid helium is used, it can be cooled down to -269°C, but it is uneconomical and has no advantage in terms of the quality of the gel.
It is best to cool it down. It is also possible to cool the product by placing it in a home refrigerator (?F5 freezer) or an ice-making compartment (-10 to -20°C), and a solid gel can be obtained by this method.

Insufficient cooling is not preferred for the present invention because the resulting gel has poor mechanical strength.

Therefore, in the present invention, a solid gel is obtained by bringing an aqueous solution or suspension containing polyvinyl alcohol and a water-soluble organic compound to a temperature of at least 16°C or below, preferably -15°C or below. . The mechanical strength of this gel is slightly affected by the cooling time mentioned above, and when cooling is continued for 4 hours or even 10 hours, the mechanical strength and elasticity increase slightly compared to when the cooling time is 1 hour, but it can be used as an ice pillow. For this purpose, cooling for 1 hour is sufficient to achieve the purpose.

The hue of the gel obtained is transparent when the cooling time is 1 to 4 hours, and white and translucent when the cooling time is 10 hours, both of which exhibit properties suitable for being used as an ice pillow substitute. When cooled, it is usually solid.

Appears like jelly or sherbet.

In the present invention, after the above-mentioned cooling treatment, dehydration is performed by vacuum drying. As the dehydration rate (the rate of cap reduction of the cooled and solidified gel) increases, the mechanical strength of the gel also improves, but if we consider its use as an ice pillow substitute, it is especially important to increase the dehydration rate and strengthen the gel. It is not necessary to obtain a gel, the dehydration rate is 5Qw
The content should be kept at t% or less, preferably 55wt% or less,
Preferable from the viewpoint of gel flexibility.

The gel after vacuum dehydration is a milky white opaque gel, but it is a solid gel that is insoluble in water even at room temperature and cannot be stored in a household refrigerator (
It will not harden even in the ice maker of a freezer.

In the present invention, a wet gel in the form of a mixed aqueous solution or suspended aqueous solution of polyvinyl alcohol and a water-soluble organic compound can be used. It may be molded to match the shape of the final object, or the molded body once obtained may be molded into a different shape by cutting or the like.

Although the gel of the present invention contains large amounts of water and water-soluble organic compounds, i;! It has similar strength and elasticity to v″K″ and ku, and even if you squeeze it tightly, it will temporarily deform, but it will immediately return to its original shape and will not lose its shape.

Even when pressure is applied to the gel of the present invention, almost no leaching of the contained liquid is observed. For example, even when a compressive stress of 2 Ky/l:J is applied, the amount of leached (outflow) liquid is 1-2% of the contained liquid. It's nothing more than that.

The gel of the present invention has no tackiness. Plate (8IEmX
8 mm x 2 tran), cylindrical (inner diameter 3,
Outer diameter 6 mm.

Approximately 1 gel molded into a spherical shape (4 mm in diameter), etc.
Oysters 1 for 10 days at room temperature in 0 g'k, 50- water
At best, no phenomena such as mutual adhesion or deformation were observed. Although it was soaked in tap water for a year, it did not dissolve and its elasticity and strength did not change. Used as a gel component (gelling component).

The coexistence of other inorganic or organic substances that do not inhibit the gelation of polyvinyl alcohol and polyvinyl alcohol does not affect the present invention. can.

The gel of the present invention includes polyvinyl chloride, polyethylene,
When packaged or sealed in a bag made of transparent [I] or opaque soft W film such as polypropylene, the original fresh appearance and feel are maintained.

Since the gel itself has a feel similar to living tissue, it can be used as a highly elastic ice pack, such as an ice pillow or an ice bag substitute, and can be used for making ice in home refrigerators (?fi freezers). Even in the chamber, it does not freeze or harden, and always exhibits a fresh texture and konnyaku-like elasticity.

Examples of the present invention will be described below.

Example 1 500 g of a 9.4 wt% aqueous solution of polyvinyl alcohol with a saponification degree of 99.5 molt, a viscosity average degree of polymerization of 2,600°, a 4% aqueous solution viscosity (20°C) of 670P, and 500 g of ethylene glycol were mixed, and 500 g of ethylene glycol was mixed. After pouring into a polyethylene container and leaving at -50℃ for 8 hours, vacuum dehydration was performed to remove 40 g of water (dehydration rate = weight loss rate of cooling body 4wt%). It has flexibility and mechanical strength t- which is superior to that of konjac, and has a compressive strength of 1OK9/17n and above L/c.

I left this in the ice maker of a household freezer overnight, but it became hard (
It did not freeze (freezing) and could withstand repeated cooling and storage at room temperature, allowing it to be used as a cold insulator.

Comparative Example 1 Example 1 is operated without ethylene glycol.

That is, polyvinyl alcohol aqueous solution 500 gk, -50
After cooling (freezing) to ℃, immediately perform vacuum dehydration to reduce water content to 17
0 g'i was removed (dehydration rate 34 wt%).

The resulting gel can be frozen and stored in a home freezer ice maker.
It stiffened and turned into a billboard.

Example 2 630 g of polyvinyl alcohol (water content 7 wt%) with a saponification degree of 97.5 molar, a viscosity average degree of polymerization of 2,200° and a viscosity of 4% water ha (at 20°C) of 55 cP was mixed with water at 4.80 molar.
0 g to make a 11.4 wt% solution.

This water-soluble i4,536g and polypropylene glycol2
．． 443g and 4.536g of it was poured into a polyethylene container with a bottom surface of 90 x 90cr11 and a depth of 1crn, which was then left at -50°C for 6 hours, and then immediately subjected to vacuum dehydration. Alms, dehydration rate 15w
t%, dehydrated amount of 680 g, and liquid content of 91 wt%. 6 From the thus obtained sheet-shaped gel (thickness: 5 mm), on the premise of sewing a vest for an adult male, the left front body, back body, and right front body were sewn in this order. Arranged length: 48m, chest measurement (including looseness)
A cut gel of 97 crn was obtained, and then the left shoulder and right shoulder were sewn together, respectively.

The cold vest thus obtained is then put into a large industrial refrigerator (=
After being left at 20°C for 8 hours, no hardening (freezing) phenomenon was observed, and an adult male was able to wear this cold vest over his work clothes and engage in high-temperature work.

Example 3 Polyvinyl alcohol (saponified 1199.5 mol).

Viscosity average degree of polymerization 2,600.4% aqueous solution (20℃
) 66 cl') powder, 158 g of propylene glycol, and 292 g of water were mixed, and after stirring at 90°C for 2 hours, this 471 g'k, diameter 20 cm, depth 2 crn
Pour into a polyethylene container and leave at -45℃ for 5 hours.
Immediately subjected to vacuum dehydration, the dehydration rate was 13 wt% (dehydration 161
g, liquid content 9.3 wt%).

The disc-shaped gel thus obtained (diameter 19, 5 ctn
.

Make a cut along the straight line 1wJ1 (radius) connecting the center of the disk (thickness 1.4crn) and any one point on the circumference, and use this cut to overlap part of the disk, By sewing them together, a cone-shaped gel without a bottom was made.

This gel did not harden even if left overnight in a household freezer, and could be used as a cup-shaped cooling material for mastitis-affected areas in maternity hospitals, wrapped in gauze.

Example 4 Two disk-shaped gels obtained by the method of Example 3 were arranged appropriately on four fan-shaped plates with a central angle of 50° and on the outer surfaces of both the left and right cups of a 7×5 rrnO long brassiere (size 95D), It was sewn onto the p-cup using polyester thread with a diameter of 0.1 tan. This was left in a home freezer for 6 hours, but no hardening was observed, and it can be used as a cooling gel with fresh elasticity and a soft texture in place of a triangular sling for cooling inflammatory ridges in maternity hospitals. did it.

Patent Applicant Nippon Oil Co., Ltd. Procedural Amendment (Voluntary) January 20, 1980 Haruki Shimada, Commissioner of the Japan Patent Office] ・Indication of IV 1982;G Patent Application No. 134311 No. 2
Title of the invention Method for manufacturing cold gel 3 Relationship with the case of the person making the amendment Patent applicant Name (Oil) (444) Nippon Oil Co., Ltd. 11°
'Toranomon Business Hall 5,
Date of Supplement 1F instruction + 1 Number of inventions increased by drawing + IE (]) "2. Scope of Claims" in the specification is amended as follows.

"2. Claims include polyvinyl alcohol with a saponification degree of 95 molar or more and a viscosity average degree of polymerization of 1,500 or more, and a water-soluble organic compound, and the concentration of the polyvinyl alcohol is 2.5 to 1.
Qwt%, an aqueous solution or suspended aqueous solution adjusted to a concentration of the organic compound of 20 to 80 wt% is poured into a container of any shape, and then cooled to a temperature lower than -6°C, and then,
A method for producing a cold-retaining gel, which comprises subjecting the gel to vacuum drying with a dehydration rate of 60 wt% or less. (2) The section ``(1) Detailed description of the invention'' in the specification is amended as follows.

Page Line Before correction After correction 812 ~ 13 ~ Cooling of suspended aqueous solution ~ Cooling of suspended aqueous solution ~ Solidification or cooling ~ 9 2 After injection into ~ After injection into ~, 13 1
2 It is difficult to reduce ~ to 20 wt% or less and ~ to ~13~14 below 20 wt%, and it is also difficult to reduce ~ to ~20 wt% or less.

descend.

13 15 At 80wt% or more, 80w
If it is higher than t%, the contribution to 14 17 is taken as the contribution to ~16 3, but this is ~
I will take ~, but this is ~20 No problem, this
No problem. As a result of this ~ By continuing to perform vacuum drying ~ 17 1 Cooling ~ In addition, cooling ~ 6
to reach ~, to reach ~, and to continue,
~ By vacuum dehydration ~13-17
obtained exhibits ~. (Deleted) 18 4
55wt% ~ 2 or more 55wt5w
t-chill 114 Deformation occurs, deformation occurs, and 20 1 1/2 amount or less ~
1/2 weight lower ~ 23 8 9.3wt
% 93wt% (3) Specification No. 18
Insert the following sentence before "After vacuum dehydration" on the 6th line of the page.

Claims (1)

[Scope of Claims] A polyvinyl alcohol having a saponification degree of 95 molt or more and a viscosity average degree of polymerization of 1.500 or more, and a water-soluble organic compound, and the concentration of the polyvinyl alcohol is 2.5 to 10.
wt%, concentration of the organic compound 20~s. After pouring an aqueous solution or suspended aqueous solution adjusted to a Wt level into a container of any shape, it is cooled to a temperature lower than -6°C, and then vacuum-dried to a dehydration rate of 60 wt% or less. A method for producing cold storage gel.