JPH0689325B2 - ice pack - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a cooling agent.

<Prior art> For applications such as cold storage of ice pillows and fresh food products, a composite obtained by mixing and molding a super absorbent resin with a molding base material such as thermoplastic resin and / or rubber is made to absorb and swell the cold insulation liquid. Is used as a cooling agent.

Such a cold insulating agent is often used as a cold storage tool in the form of being filled in a bag made of synthetic resin such as polyvinyl chloride or polyethylene, or made of rubber. And as a manufacturing method of such a cool storage tool, the above-mentioned complex and cold storage liquid are inserted into a bag,
An efficient method is to allow the composite to stand for a predetermined time to absorb and swell the cold storage liquid.

<Problems to be Solved by the Invention> However, when the composite that does not expand uniformly in the cold-retaining liquid, that is, the composite having different expansion ratios in the longitudinal and lateral equal directions, is used in the production of the above-described cool storage device, However, various problems such as a decrease in product yield occur, resulting in a decrease in production efficiency. The reason is that since the composite does not expand uniformly, the composite after expansion does not fit well with the bag, and a gap is generated in the bag.

As a result of various studies on the cause of non-uniform expansion, the present inventors have found that the expansion is performed uniformly by adopting a molding method that reduces strain due to orientation or the like when molding the composite.

That is, since the composite obtained by mixing the thermoplastic resin and / or the rubber with the highly water-absorbent resin generally has a significantly lower flowability at the time of molding than the thermoplastic resin or the rubber alone, at the time of molding. Although the strain due to the orientation and the like is large, it is possible to uniformly expand by adopting a molding method that reduces this strain.

As a result of various studies on the molding method for eliminating the distortion of the molded product due to the orientation and the like, the present inventor has found that the extrusion molding method is the best, and arrived at the present invention.

<Means for Solving Problems> The present invention relates to a cold insulating agent obtained by immersing and swelling a composite obtained by mixing a superabsorbent resin with a molding base material in a cold insulating liquid such as water. There is provided a cooling agent using a material that expands evenly.

The composite in the present invention is a mixture of a molded base material and a superabsorbent resin.

As the molding substrate, one made of a thermoplastic resin and / or rubber can be preferably used.

As the thermoplastic resin, 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), Examples thereof include styrene-butadiene-styrene block polymer (SBS), polyvinyl chloride and vinyl chloride copolymer. Also, as rubber,
For example, in addition to natural rubber, various synthetic rubbers such as chloroprene, ethylene-propylene copolymer, polybutadiene, polyisoprene, styrene-butadiene copolymer, silicone rubber and urethane rubber can be mentioned. When rubber is used, a usual inorganic filler (for example,
It is necessary to add clay, silica, calcium carbonate), a vulcanizing agent (for example, powdered sulfur, peroxide), a vulcanization accelerator (for example, thiuram-based, thiazole-based, dithiocarbamate-based), an antioxidant and the like. In addition, a colorant, a foaming agent, an antiseptic, an antifungal agent, a fragrance, a surfactant and the like may be added as required.

Further, as the super absorbent resin 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.

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 composite is one that expands uniformly in the cold insulation liquid,
The extrusion molding method is the most excellent method for producing it.

The structure of the screw and die in the extrusion molding method is
Any one can be used without particular limitation as long as it is used for usual molding of thermoplastic resins.

Examples of the cold-preserving liquid used in the present invention include water or a mixture of water and a freezing point depressant.

Examples of the freezing point depressing substances include monohydric or dihydric or higher alcohols, and especially those consisting of monohydric or dihydric or higher alcohols and urea prevent the solidification of the cold-preserving agent and improve the shape retention. It is preferably used to maintain flexibility.

Here, alcohols are monohydric, dihydric, trihydric and polyhydric alcohols that are usually used as antifreeze liquids,
Examples thereof include ethanol, ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, glycerin, petataerythritol and the like, with ethylene glycol and propylene glycol being preferred.

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 usually 5 to 80 parts by weight of alcohols and 5 to 100 parts by weight of urea to 100 parts by weight of water. The range of the part is preferable for maintaining flexibility and shape retention.

<Effect> The cold insulating agent of the present invention is filled in a bag made of synthetic resin such as polyvinyl chloride or polyethylene, or made of rubber to be used as a cold storage tool.

Such a cool storage device, by inserting the complex and cold storage liquid into a bag,
The opening is sealed and left for a predetermined time. It can be made by an efficient method. Since the composite of the present invention expands uniformly, the composite after swelling fits well with the bag.

This is because the composite swells in proportion to the length in each direction.
As a result, the product yield is improved, and the production efficiency is further improved.

The thus obtained ice pack can be used as a cold storage device by the method described above, etc., and when cooled in a refrigerator or the like, as a simple ice pack for ice pillows, vegetables, food and drink, fish and shellfish, for keeping ice in a very wide field. It can be used repeatedly.

<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". The expansion ratio and expansion ratio in the examples are based on the following definitions.

Wo = dry sample weight W = dry sample (size 20 x 20 x 2 mm) kept at 20 ° C
Weight after soaking in cold liquid for 72 hours,MD = 20 ° C. × longitudinal length after 72 hours (cm) TD = 20 ° C. × 72 hours lateral length (cm) Example 1 Styrenic thermoplastic elastomer (Sorprene) T-47
5, Asahi Kasei product 100 parts and super absorbent resin (Sumika gel) SP
-520, Sumitomo Chemical Co., Ltd.)
After that, it is made into pellets, and the uniaxial 60 mmφ extruder (hanger core
Molded at a resin temperature of 185 ° C, width: 20 mm, thickness: 2
An extruded sheet of mm was obtained.

Pre-prepared 15% ethylene glycol aqueous solution
Immerse the above water-swellable molding substrate in 500 g, and at 20 ° C,
After standing for 72 hours, the expansion ratio and expansion ratio were measured.

The obtained results are shown in Table 1.

Example 2 Styrenic thermoplastic elastomer (Califlex TR
1112, Ciel Chemical Co., Ltd.) 100 parts and super absorbent resin (KI gel 2
01K, average particle size: 8μ, Kuraray Isoprene Chemical Co., Ltd.) 1
Using 00 parts, in the same manner as in Example 1, width: 20 mm, thickness: 2 m
An extruded sheet of m was obtained.

Using the water-swellable molding substrate obtained above, the expansion ratio and the expansion ratio after standing at 20 ° C. for 72 hours were measured in the same manner as in Example 1. The obtained results are shown in Table 1.

Example 3 Instead of the styrene thermoplastic elastomer, ethylene-vinegar was used.
Vinyl acetate copolymer (Evatate 5011, Sumitomo Chemical Co., Ltd.)
Width: 20 mm, thickness as in the example except that
S: A 2 mm extruded sheet was obtained.

Using the water-swellable molding substrate obtained above, the expansion ratio and the expansion ratio after standing at 20 ° C. for 72 hours were measured in the same manner as in Example 1.

The obtained results are shown in Table 1.

Example 4 Califlex used in Example 2 Conducted TR1112 with 50 copies
Evatate used in Example 8 Using 50 parts of 5011, super absorbent tree
Fat (Sumika gel SP-520, Sumitomo Chemical Co., Ltd.) 100 parts
Otherwise, in the same manner as in Example 1, width: 20 mm, thickness: 2 mm
The extruded sheet was obtained, and the expansion ratio and
And the expansion ratio was measured.

The obtained results are shown in Table 1.

Example 5 Super absorbent resin (Sumika gel SP-520) 200 parts
At the same time, kneading with an open roll for about 15 minutes,
A complex was obtained. Use the above unvulcanized rubber composite with 70 mmφ rubber
Width: 20 mm, thickness: 2 mm using an extrusion extruder (plate die)
An extruded sheet was obtained, and then a vulcanization kettle was used for 8 hours at 140 ° C.
72 hours at 20 ° C. in the same manner as in Example 1 in which time vulcanization was performed
The subsequent expansion ratio and expansion ratio were measured.

The obtained results are shown in Table 1.

Example 6 An extruded sheet having a width of 83 mm, a length of 140 mm and a thickness of 5 mm was obtained using the uniaxial 70 mmφ extruder (hanger coat die) according to the method of Example 1.

Pre-made PVC bag (inside size, 285 × 175m
Prepare a cold insulation liquid containing 600 g of 15% ethylene glycol aqueous solution in m), insert the extruded sheet obtained above,
Expanded at 20 ° C. After about 3 days, it expanded uniformly in a polyvinyl chloride bag to a size of 270 x 165 mm and a thickness of 10 mm.

Comparative Example 1 Pellets were prepared with the same composition as in Example 1, and a 3.5 oz. Injection molding machine (manufactured by NISSEI PLASTIC CO., LTD.) Was used. Resin temperature: 140
C, injection pressure: 80 Kg / cm ² , mold cooling temperature: 15 ° C., and a test piece (40 mm × 60 mm, thickness 2 mm) was prepared. Using the obtained test piece, cut into a size of 20 mm × 20 mm,
After being left at 20 ° C. for 72 hours in the same manner as in Example 1, the expansion ratio and expansion ratio were measured. Table 1 shows the results obtained.
It was shown to.

Comparative Example 2 Pellets were prepared with the same composition as in Example 2, and test pieces were prepared under the injection molding conditions of Comparative Example 1.

Using the test piece obtained, in the same manner as in Example 1.
The expansion ratio and expansion ratio after standing for 72 hours at 20 ° C. were measured.

The obtained results are shown in Table 1.

Comparative Example 3 Using the pellets produced in Comparative Example 1, using an 8 ounce injection molding machine, resin temperature: 145 ° C., injection pressure: 100 Kg / cm ² , mold cooling temperature: 15 ° C., a test piece (83 mm × 140 mm) was used. , Thickness: 5m
m) was created. Using the obtained test piece, it was inserted into an aqueous solution of 15% ethylene glycol in the same manner as in Example 6, and the state of expansion after about 3 days was examined. , Thickness: 8mm.

This was placed in a refrigerator and cooled at −20 ° C. for 24 hours, but the molded body did not expand into the entire polyvinyl chloride bag. Also, while carrying it by hand, deviations may occur, walking of water may occur,
It was not always suitable as an ice pillow.

Claims (2)

[Claims] 1. A cold-preserving agent obtained by immersing and expanding a composite body obtained by mixing a superabsorbent resin into a molding base material and expanding uniformly. 2. The cold-preserving agent according to claim 1, wherein a composite made by an extrusion molding method is used as the composite.