JPH0689324B2 - ice pack - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention can maintain shape retention and flexibility even at low temperature,
The present invention relates to a freezing agent that can be transformed.

<Prior art and its problems> Conventionally, an aqueous solution of a water-soluble polymer compound such as starch, carboxymethylcellulose, polyvinyl alcohol, a polymer of acrylic acid or a derivative thereof, or a solidified Zeru substance is a cooling medium. Is commonly used as.

However, since the liquid part of these media consists almost entirely of water, when the ice pack is cooled to 0 ° C or below, the whole ice pack freezes, showing a very hard and brittle property, and the shape-retaining property is maintained. Then, the flexibility was lost, and it was unsuitable as a cooler. In order to improve the drawbacks of freezing and solidification, a freezing point depressant is added to an aqueous solution of the above water-soluble polymer compound, thereby lowering the freezing point of water,
Attempts have been made to retain flexibility even when frozen, but it is difficult to handle because it has fluidity at normal temperature (the ice pack is biased to one side), or if it breaks, the ice pack will flow out. However, there is still nothing to be satisfied.

On the other hand, in an aqueous solution containing a water-soluble polymer compound and a freezing point depressing substance, liquid paraffin, petrolatum, oleic acid and other oily substances, and water-insoluble calcium carbonate, barium sulfate, synthetic resin powders and other solid substances A heating medium in which a fine powder substance is dispersed has also been proposed.

However, this heat medium is difficult to maintain a stable dispersed state in the composition when the shape and specific gravity of the added oil-like substance or solid fine powder substance is different, and when it is repeatedly used for a long time, it is difficult to cool. It has a drawback that it may partially freeze.

<Means for Solving Problems> As a result of intensive studies to solve the above-mentioned drawbacks of the prior art, the present inventors have found that water (A), alcohols (B) and urea (C) are essential components. A cold insulation liquid consisting of a thermoplastic resin / or a rubber mixed with a highly water-absorbent resin is immersed in the cold insulation liquid, and the cold insulation agent used by expanding the composite is cooled to -20 ° C. They have found that they retain their shape-retaining property and flexibility without solidifying at all and have an excellent cold-retaining ability, and have completed the present invention.

The alcohols (B) used in the present invention are monohydric, dihydric, octahydric and polyhydric alcohols which are usually used as an antifreeze, and include, for example, ethanol, ethylene glycol, propylene glycol, diethylene glycol,
Polyethylene glycol, polypropylene glycol,
Examples thereof include glycerin pentaerythritol, and ethylene glycol and propylene glycol are preferable.

Further, as the thermoplastic resin used in the present invention, for example, ethylene-vinyl acetate copolymer or a saponified product thereof, chlorinated polyethylene, sulfonated polyethylene,
Ethylene-acrylic acid copolymer, styrene-isoprene-styrene-block copolymer (SIS), styrene-
Examples of the rubber include butadiene-styrene block polymer (SBS), polyvinyl chloride, and vinyl chloride copolymer. Examples of the rubber include natural rubber, polychloroprene, ethylene-propylene copolymer, polybutadiene, and polyisoprene. , Various synthetic rubbers such as styrene-butadiene copolymer, silicone rubber, urethane rubber. When rubber is used, ordinary inorganic fillers (eg, clay, silica, calcium carbonate), vulcanizing agents (eg, powdered sulfur, peroxide), vulcanization accelerators (eg, thiuram-based, thiazole-based, It is necessary to add dithiocarbamate), anti-aging agent, etc. In addition, a colorant, a foaming agent, an antiseptic, an antifungal agent, a fragrance, a surfactant and the like may be added as required.

As the super absorbent polymer used in the present invention, those which are insoluble in water and have a water absorption capacity in the range of 80 to 1000 times its own weight can be used, for example, vinyl acetate-acrylic acid ester copolymer Compound, a salt of a crosslinked product of a modified isobutylene-maleic anhydride copolymer, a polyacrylic acid (salt) having a crosslinked structure, a salt of a starch-acrylic acid copolymer, a modified product of polyethylene oxide, a crosslinked polyacrylamide or the like. Examples include modified products and crosslinked polyvinyl alcohol. However, the gel strength of the superabsorbent resin after water absorption is strong, there is no decay of the gel, and long-term durability is required. Among them, saponified vinyl acetate-acrylic acid ester copolymer or isobutylene-maleic anhydride is used. A salt of a crosslinked product of a modified acid copolymer is preferably used.

Further, a composite formed by mixing a thermoplastic resin and / or rubber with a highly water-absorbent resin can be easily produced by a commonly known method.

The amount of the super absorbent resin contained in the composite varies depending on the purpose of use, but is preferably in the range of 30 to 70% by weight.

The addition ratio of the freezing point depressing substance to water is determined by the relationship between the desired freezing point depressing temperature and the cold storage temperature to be used, but normally 100 parts by weight of water (A) and 5 parts of alcohols (B)
A range of -80 parts by weight and 5-100 parts by weight of urea (C) is preferred.

The manufacturing method of the cold insulating agent of the present invention is water (A), alcohol (B)
It suffices to immerse the composite made by mixing the thermoplastic resin and / or the rubber with the highly water-absorbent resin in the cold insulation liquid containing urea and urea (C) for a predetermined time.

Since the expanded composite has shape retention and flexibility even when cooled, it may be brought into direct contact with the object to be cooled, or it may be inserted into an appropriate bag or container that is usually used. It can be used in various forms.

<Effect> The thus obtained cold-preserving agent of the present invention does not solidify at all even when it is strongly cooled, and has both shape-retaining property and flexibility. Filled in a synthetic resin or rubber bag such as polyethylene, sealing the opening and cooling with a refrigerator, etc., it is extremely wide as a simple ice pack such as ice pillows, vegetables, food and drink, fish and shellfish. It can be used repeatedly to keep the field cool.

<Example> Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited thereby.

In the examples, "parts" means "parts by weight". In addition, the water absorption amount (times) in the examples is based on the following definition.

Wo = weight of dried sample W = weight of dried sample after soaking in cold liquid at 20 ° C for 72 hours, performance test of cold-insulating agent ...... Complex expanded in cold-liquid-
Shape retention, flexibility and 20
The cooling time until the temperature reached ℃ was measured by a thermocouple.

Example 1 Ethylene-vinyl acetate copolymer (Sumitomo Chemical Co., Ltd. Sumite
Out RB-11, VA = 41%, MI = 60) High absorption against 100 parts
Water-based resin (Sumitomo Chemical Co., Ltd. Sumika Gel) SP-520) 100 copies
And kneaded with an open roll at 80 ° C for about 10 minutes
After that, press at 120 ° C to obtain a press sheet with a thickness of about 5 mm.
It was

In advance, the complex of 20 mm square obtained above was immersed in 500 ml of the example solution containing 25 parts of ethylene glycol (B) and 30 parts of urea (C) in 100 parts of water (A). Then, the water absorption and the performance of the retaining agent were examined. The obtained measurement results are shown in Table 1.

Example 2 Styrene-isoprene-styrene block copolymer
(Ciel Chemical (manufactured) Califlex TR1112, styrene
/ Rubber ratio = 14/86) against 100 parts of super absorbent resin (Kuraray
Isoprene Chemical Co., Ltd. KI201K is crushed to an average particle size of approx.
20 μm) 100 parts, and open at 140 ° C.
For about 15 minutes, then press at 150 ° C for about 5 mm
A press sheet having a thickness was obtained.

The obtained pressed sheet (size 20 mm square) was immersed in 500 ml of the cold insulation liquid prepared at the same ratio as in Example 1, and the water absorption amount and the performance of the cold insulation agent were examined. Table of the obtained measurement results
Shown in 1.

Example 8 Super absorbent resin (Sumika gel SP-520) 200 parts blended below
Knead together with the product for about 15 minutes on an open roll to
A complex was obtained.

This unvulcanized rubber composite was vulcanized with a steam press at 160 ° C. for 10 minutes to obtain a press sheet having a thickness of 5 mm.

By the same method as in Example 1, the water absorption amount and the performance of the retaining agent were investigated. The obtained measurement results are shown in Table 1.

Comparative Example 1 100 ml of the cold preservation liquid obtained in Example 1 was mixed with Sumika gel. SP-5
The performance of the cooling agent in which 5 parts of 20 was mixed was examined. Obtained measurements
The results are shown in Table-1.

Comparative Example 2 The composite (size 20 mm square) obtained in Example 1 was immersed in 500 ml of a cold preservation liquid which was prepared by mixing 20 parts of ethylene glycol (B) with 100 parts of water (A) in advance. The amount of water absorption and the performance of the cooling agent were investigated.

The obtained measurement results are shown in Table 1.

Comparative Example 3 The complex (size 20 mm square) obtained in Example 3 was immersed in 500 ml of a cold-preserving liquid consisting of 100 parts of water (A) and 25 parts of urea (C) in advance to absorb the water. The amount and performance of the ice pack was investigated. The obtained measurement results are shown in Table 1.

From Table 1, it is clear that in the case of the example, both the cold insulation property and the flexibility are excellent.

Claims (1)

[Claims] 1. A composite obtained by mixing a thermoplastic resin and / or rubber with a highly water-absorbent resin is immersed in a cold insulation liquid comprising water (A), alcohols (B) and urea (C),
Cooling agent obtained by expanding the composite