JPH0545636B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of practical application) The present invention relates to a cold insulating material that has excellent flexibility and elasticity at low temperatures and has a large amount of heat retention.

(Prior art and its problems) Many commercially available cold insulation materials use gels made by adsorbing water to water-soluble polymers such as zetylan, polyvinyl alcohol, or polyethylene oxide (Japanese Patent Laid-Open No. 56-36538). Public bulletin and special public notice 1977
45977), this gel solidifies very hard at low temperatures and has no low-temperature flexibility. Therefore, it is not suitable for use as a substitute for a water pillow.

Japanese Patent Publication No. 47-18409 discloses an oily gel consisting of an unvulcanized elastic block copolymer and paraffin oil, but although these are flexible, they are poor in cold retention.

JP-A No. 60-79061 discloses a continuous phase consisting of a teleblock copolymer elastomer and an oil component in which water-containing water-absorbing cross-linked polymer particles are dispersed, and JP-A No. 60-11738 discloses A water-in-oil emulsion in which an aqueous dispersoid is dispersed in a homogeneous dispersion medium containing a high-boiling oily substance, natural rubber, or synthetic rubber is crosslinked in the presence of a crosslinking agent to form a gel. There is. Although all of these have excellent cold storage properties, they solidify at low temperatures around -20°C.

Therefore, there is a demand for a cold insulating material that maintains flexibility even at temperatures around -20°C and has a long cooling time.

(Means for Solving the Problems) The present inventors studied various materials, and as a result, they arrived at the present invention.

That is, the present invention provides a cold insulating material containing a gelled vinyl chloride resin mixed with a plasticizer and a water-containing hydrogel whose surface is coated. Generally, simply mixing a vinyl chloride resin gelled with a plasticizer and a water-containing hydrogel tends to cause phase separation, and when cooled, it solidifies hard and lacks flexibility.

As a result of various studies, we found that a mixed composition of a vinyl chloride resin gelled by mixing a plasticizer with a water-containing hydrogel coated on the surface has sufficient flexibility even at a low temperature of -20°C and has a low temperature retention time. I found out a long time ago.

Plasticizers used in the present invention include dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl adipate (DOA), dioctyl sebacate (DOS), dioctyl azelate (DOZ), diisononyl adipate (DINA),
General-purpose plasticizers such as diisodecyl phthalate (DIDP) and diisodecyl adipate (DIDA) can be used, but it is preferable to use DOP and DOA in combination. The plasticizer is used in an amount of 15 to 45 times, preferably 30 to 40 times, the amount of the vinyl chloride resin. If the amount is less than 15 times, the elastic modulus of the resin itself will be high, resulting in problems such as poor dispersion of hydrogels during processing. It has the disadvantage that layer separation of the vinyl chloride resin occurs.

Here, the term "hydrated hydrogel" refers to a generally known hydrogel, such as a starch-based hydrogel, an acrylic acid-based hydrogel, or an acrylic acid-vinyl alcohol-based hydrogel, to which an appropriate amount of water is added to make it hydrated. It is preferable to use this product in an amount of 1 to 8% by weight, particularly 5 to 6% by weight based on water, with some water absorption capacity remaining as a hydrogel. If it is less than 1% by weight, water that has been absorbed into the hydrogel will be released due to external pressure, etc. If it exceeds 8% by weight, the absorption rate of each water-containing hydrogel will be uneven, making it difficult to keep cool. It has the disadvantage that it takes less time.

In the present invention, the water-containing hydrogel described above is further surface-coated. In this case, the surface-coated hydrogel surface may be cured before use. If such surface treatment is not performed, the water retaining material composition will easily separate, making it difficult to form a uniform composition.

As surface coating agents, protective colloids such as sodium alginate, gelatin, gum arabic, gum tragacanth and polymeric polyhydric alcohols such as polyvinyl alcohol are used. As auxiliary agents for hardening, soaps such as calcium salts and aluminum salts of higher fatty acids, inorganic acids such as hydrochloric acid, sulfuric acid, and boric acid, and organic acids such as oleic acid and acetic acid are used. These surface coating and curing treatments can be carried out by adding 10 to 15% by weight aqueous solution of these surface coating agents to the hydrogel in an amount of 1/2 to the same amount, or adding 10 to 20% by weight of the above-mentioned curing aid. In addition, a curing treatment is performed. The water used in the present invention may or may not contain anti-icing agents such as ethylene glycol and diethylene glycol.

In addition, in the present invention, it is preferable to add a filler to maintain shape and prevent flow when not frozen, and fillers used include inorganic oxides such as white carbon, talc, titanium oxide, and oil-absorbing calcium carbonate. , long-chain fatty acid salts, especially calcium stearate, magnesium stearate, aluminum stearate, calcium oleate, etc., may be used alone or in combination of two or more. The finer the particles of these fillers, the better. The amount to be used is 2 to 2 to
40% by weight is used, preferably 10-15% by weight.
If it is less than 2% by weight, it is insufficient for shape retention and prevention of flow, and if it exceeds 40% by weight, it has the disadvantage of being too hard.

(Effect of the invention) The thus obtained cold insulating material composition not only does not lose its flexibility at -20°C when cooled even when immersed in hot water, but also shows no change even after being repeatedly warmed and cooled. I can't. Therefore, it is very easy to use and has excellent thermal efficiency.

The cold insulation material based on the present invention is used for cold insulation pillows, blood cold storage, frozen desserts cold storage, foodstuffs cold storage, and the like.

(Example) The present invention will be explained in more detail below using Examples, but is not limited thereto.

Example 1 20g of hydrogel (Sumitomo Chemical S-50) and water
370 g was thoroughly mixed to make it hydrated, a solution of 10 g of sodium alginate dissolved in 200 g of water was added and stirred, and 20 g of calcium stearate was added and mixed (step). Separately, 15g of vinyl chloride resin (Sumitomo Chemical PX-QHH), 450g of dioctyl phthalate (DOP), and dioctyl adipate (DOA)
100g were mixed, heated to 140°C, and stirred well (step). The composition obtained in the step was added to the composition obtained in the above step and stirred well. The obtained cold insulating material was flexible enough to fit the affected area even when cooled to -20°C, and did not become hard even after repeated use. Next, cool it to -20℃ and add it to boiling water for 15 minutes.
The mixture was heated for a minute, kneaded by hand, frozen again at -20°C, and this operation was repeated. Similarly, a water-containing hydrogel without surface coating was prepared, and the above operation was repeated. The one with the surface coating did not become hard even after repeating the operation 15 times, but the one without the surface coating became hard after two operations.

Example 2 30 g of talc powder was further added to the mixture heated in the step of Example 1, stirred, and the same operation was performed. The obtained cold insulating material was flexible enough to fit the affected area even when cooled to -20°C, and did not become hard even after repeated use. It was also effective in maintaining shape and preventing flow when not frozen. next,
The mixture that had been cooled to -20°C was heated in boiling water for 15 minutes, kneaded by hand, frozen again to -20°C, and this operation was repeated. Similarly, a water-containing hydrogel without surface coating was prepared, and the above operation was repeated. The one with the surface coating did not become hard even after repeating the operation 15 times, but the one without the surface coating became hard after two operations.

Example 3 In the same manner as in Example 1, 10 g of polyvinyl alcohol was dissolved in 200 g of hot water and crosslinked with 1 g of boric acid glass instead of sodium alginate.
As in Example 1, the resulting cold insulating material maintained sufficient flexibility to fit the affected area even at -20°C. Then −20
The mixture that had been cooled at ℃ was heated in boiling water for 15 minutes, kneaded by hand, frozen again at -20℃, and this operation was repeated.
Similarly, a water-containing hydrogel without surface coating was prepared, and the above operation was repeated. The one with the surface coating did not become hard even after repeating the operation 15 times, but the one without the surface coating became hard after two operations.

Example 4 In the same manner as in Example 2, fine powder of white carbon was used instead of talc, but as in Example 1, a flexible cold insulating material that satisfactorily fit the affected area even at -20°C was obtained. Next, cool it to -20℃ and add it to boiling water.
The mixture was heated for 15 minutes, kneaded by hand, frozen again at -20°C, and this operation was repeated. Similarly, a water-containing hydrogel without surface coating was prepared, and the above operation was repeated. The one with surface coating did not become hard even after repeating the operation 15 times, but the one without surface coating did not become hard even after repeating the operation 15 times.
It got hard in the third session.

Claims (1)

[Claims] 1. A cold insulating material containing a gelled vinyl chloride resin mixed with a plasticizer and a water-containing hydrogel whose surface is coated. 2. The cold insulating material according to item 1, wherein the surface is coated with a protective colloid or a polymeric polyhydric alcohol.