JP2003079680A - Cold insulation material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cold insulation material for perishables/funerals and festivals having sufficient cold insulation effect in place of dry ice and solving a pollution problem. SOLUTION: In the cold insulation material constituted by sealing a cold insulation medium in a container comprising a water impermeable substrate, a packaging material prescribed as follows is provided to a part or whole of the outer surface of the cold insulation material. The packaging material comprises a sheet obtained by covering a water absorbing sheet (B) comprising a water absorbable resin (S) with a water permeable water insoluble sheet (A) in a sealed state and the water absorbing speed of the water absorbable resin (S) is 5-400 sec when measured by a water absorbing speed testing method according to the testing method of JIS K7224-1996 other than that the sample mass of the water absorbable resin (S) is set to 2.00 g and the concentration of a saline solution is 10 mass %.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a cold insulating material.
More specifically, the present invention relates to a cold insulating material useful for cooling perishables and bodies.

[0002]

2. Description of the Related Art Most conventional cold insulating materials have a cold insulating medium enclosed in a container made of an impermeable base material.
However, in the conventional cold insulating material, as a result of rapidly cooling the outside air with the cold insulating material that has been cooled in advance, dew condensation occurs on the surface of the cold insulating material due to this temperature change. This condensed water reduces the freshness of articles that you want to keep cool, such as fresh vegetables, seafood, livestock meat, and dairy products, and the condensed water that exudes reduces the strength of the container that packs the items that you want to keep cool. There were problems such as burial, and it was desired to solve it. As a solution to the above problems, a part or all of the outer surface of the container made of a water-impermeable base material enclosing a cold insulating medium is permeable to water through an intermediate layer mainly composed of a water-absorbent resin. A cold insulating material (see Japanese Patent No. 2602040) characterized by having an outer layer made of an insoluble base material is introduced. Further, although dry ice is used for preservation and cooling of the body, reduction of oxygen dioxide is desired as a global warming preventive measure, and a cold insulating material that replaces dry ice is desired. When a conventional cold insulator is used as a cold insulator for a corpse, there is a problem that the keeping time is inferior to that of dry ice and the corpse decays too quickly.

[0003]

SUMMARY OF THE INVENTION However, the above-mentioned problems are caused by providing an outer layer made of a water-permeable and water-insoluble base material on the surface of a conventional cold insulating material via an intermediate layer mainly composed of a water-absorbing resin. When the drip (meat juice) generated from meat such as raw meat or the drip generated from the body is absorbed, the surface of the cold insulating material is contaminated and cannot be replaced, making it difficult to repeatedly use it, which was an advantage of the conventional cold insulating material. It was inconvenient.

[0004]

Means for Solving the Problems As a result of intensive investigations by the inventors of the present invention to obtain a cold insulating material with which the above problems have been improved, a cold insulating material obtained by enclosing a cold insulating medium in a container made of an impermeable base material. By covering with a packaging material that has water absorption and water retention,
The present invention has been completed by finding that the layer that absorbs dew condensation water on the surface of the cold insulating material and further absorbs the dew condensation water appropriately suppresses heat conduction, and as a result, the cold keeping duration of the cold insulating material can be extended.
That is, the present invention provides a cold insulating material obtained by enclosing a cold insulating medium in a container made of an impermeable base material, wherein the following packaging material is provided on a part or all of the outer surface of the cold insulating material. It is a cool material. Packaging material: a sheet obtained by wrapping a water-absorbent sheet (B) made of a water-absorbent resin (S) in a water-permeable water-insoluble sheet (A) and sealing the water-absorbent sheet according to the following water-absorption rate test method of the (S). Is a sheet of 5 to 400 seconds. Water absorption rate test method: JIS K 722 except that the sample weight of the (S) is 2.00 g and the salt solution concentration is 10% by weight.
The test method based on the test method of 4-1996.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The water-permeable, water-insoluble sheet (A) used in the packaging material of the present invention may be flexible and water-permeable, but the water-absorbing sheet (B) has the surface of the cold insulating material. The form and material are not particularly limited as long as the swelling force does not break even if it absorbs and swells dew condensation water. Here, the water permeability is 3 in terms of the time (seconds) in which 100 ml of ion-exchanged water at 25 ° C. passes through an area of 100 cm ^2.
It is 0 seconds or less, preferably 15 seconds or less, and particularly preferably 5 seconds or less. Normal strength is 2 kg both vertically and horizontally
/ Cm or more, preferably 3kg / cm or more tear strength is required, wet strength (tensile strength after 1 minute immersion in 25 ° C ion-exchanged water) is 0.05kg / cm or more, preferably 0.1kg / cm cm or more is required. The water-permeable and water-insoluble sheet is not particularly limited as long as it has holes through which water can pass, but the size of the holes is preferably 0.01 to 1 mm, particularly preferably 0.
Any value may be used as long as it is from 01 to 0.5 mm and the water-absorbent resin powder does not easily leak. The thickness of the sheet is preferably 0.1
-5 mm, more preferably 0.5-3 mm. The size of the sheet is not particularly limited.

Examples of the material include natural fibers such as cotton, wool, silk, cellulose, pulp, polyester, nylon,
Applicable are synthetic resins or fibers such as acrylic, polyethylene, polypropylene, polyurethane, polystyrene, poval and its modified products, semi-synthetic fibers such as rayon and acetate, and mixed materials thereof, and paper materials such as western paper and Japanese paper.

The form of the sheet is, for example, knitted fabric, woven fabric,
Cloths such as non-woven fabrics; mesh films such as polyethylene and polypropylene sheets with many fine holes formed therein; papers such as western paper and Japanese paper. Among these, non-woven fabric is particularly preferable. Nonwoven fabrics are described in detail in "Basics and Applications of Nonwoven Fabrics" (published by the Japan Textile Machinery Society). Further, when fixing by a heat fusion method, a material containing a heat fusion substance such as a heat fusion fiber and / or a film is used, but "the actual condition of the heat fusion nonwoven fabric and the whole volume of the heat fusion fiber" 198
Those described in detail in Osaka Chemical Marketing Center Co., Ltd., issued April 24, 1997, are listed.

The water absorbing sheet (B) used in the packaging material in the present invention is not particularly limited as long as it absorbs dew condensation water generated on the surface of the cold insulating material and body fluid from the body. For example, cotton-like materials of various fibers such as wood pulp and various fibers such as water-absorbent fibers are formed into a sheet by an appropriate method such as papermaking, mechanical attachment, binder, spunbond, spunlace; A laminate obtained by fixing the water-absorbent resin powder to these cotton-like materials or laminates; spraying the water-absorbent resin powder on the above base material, sandwiching it with the other base material in a sandwich form, and embossing method , A needle punching method, a stitch bonding method, a fusion bonding method, and the like in which a water absorbent resin is integrated. The position of the water-absorbent resin on the water-absorbing / water-holding base material is preferably continuously sprayed whether it is the entire surface of the base material or a linear shape having a width. Among these, preferred ones are cotton pulp cotton-like materials or laminates having water-absorbent resin powder fixed thereon, and adhesives on one or both sides of a base material such as plastic, cloth (particularly preferably non-woven fabric), and paper. Or those in which water-absorbent resin powder is immobilized using a binder resin, those in which the water-absorbent resin is integrated by an embossing method or a needle punch method, and more preferable ones are cotton pulp cotton-like materials and laminates. With water-absorbent resin powder fixed on it, embossing method, water-absorbent resin integrated by needle punching method, or with water-absorbent resin powder fixed on one or both sides of the plastic film with an adhesive. Alternatively, for example, using a cellophane or vinyl adhesive tape, water-absorbent resin powder may be sprayed on the adhesive surface and fixed with a pressure roll. The preferred reason is that it is difficult to prevent swelling of the water-absorbent resin powder, so that dew condensation water and body fluid from the body can be quickly absorbed, and the productivity is good and the economy is high.

As the adhesive or binder resin, known acrylic resins, epoxy resins, urethane resins, ester resins and the like can be used, and any of water-based, solvent-based and solvent-free resins can be used. At the time of use, it can be applied to the substrate as it is or diluted with water or a solvent (methanol, ethanol, acetone, methyl ethyl ketone, ethyl acetate, butyl acetate, etc.) to an arbitrary concentration. The coating method is a roll coater, line coating such as brush coating, or a coating method used for on-site coating. The dry film thickness is preferably 0.
1 μm to 3 mm, more preferably 1 μm to 1 m
m. It is preferable to spray a water-absorbent resin during or after drying after coating. Here, the fixed amount of the water-absorbent resin powder is usually 1 to 100 g / m2, preferably 5 to 55 g / m2.
Is. When the fixed amount is 1 g / m2 or more, absorption of dew condensation water is good. On the other hand, when it is 100 g / m2 or less, the performance and cost performance in terms of economy are good.

In the present invention, the water absorbing sheet (B) of the covering material
Examples of the water absorbent resin (S) used in
(1) to (5) are mentioned. (1) 1 selected from a polysaccharide (a-1) and / or a monosaccharide (a-2) such as starch or cellulose, a water-soluble monomer and / or a monomer which becomes water-soluble by hydrolysis
A water-absorbent resin obtained by polymerizing at least one kind of monomer (b) and a cross-linking agent (c) as essential components and performing hydrolysis if necessary. Examples of (a-1) include sucrose, cellulose, CMC, starch and the like, and examples of (a-2) include pentaerythritol, diglycerin, sorbitol, xylitol, mannitol, dipentaerythritol, glucose and fructose. .
Examples of (b) include radically polymerizable water-soluble monomers having a carboxyl group, a sulfonic acid group, and a phosphoric acid group, and salts thereof. Examples of the radically polymerizable water-soluble monomer having a carboxyl group include unsaturated mono- or poly (divalent to hexavalent) carboxylic acid [(meth) acrylic acid (acrylic acid and / or methacrylic acid. The same below. Description is used), maleic acid, maleic acid monoalkyl (C1-9) ester, fumaric acid, fumaric acid monoalkyl (C1-9) ester, crotonic acid, sorbic acid, itaconic acid, itaconic acid monoalkyl. (C1-9) ester, itaconic acid glycol monoether, cinnamic acid, citraconic acid, citraconic acid monoalkyl (C1-9) ester, etc.] and their anhydrides [maleic anhydride, etc.] and the like. To be

Examples of the radical-polymerizable water-soluble monomer having a sulfonic acid group include aliphatic or aromatic vinyl sulfonic acids (vinyl sulfonic acid, allyl sulfonic acid, vinyl toluene sulfonic acid, styrene sulfonic acid, etc.), 2 −
Hydroxy-3- (meth) acryloxypropyl sulfonic acid, (meth) acrylalkyl sulfonic acid [(meth)
Sulfoethyl acrylate, sulfopropyl (meth) acrylate, etc.], (meth) acrylamidoalkylsulfonic acid [2-acrylamido-2-methylpropanesulfonic acid, etc.] and the like. Examples of the radical-polymerizable water-soluble monomer having a phosphoric acid group include (meth) acrylic acid hydroxyalkyl phosphoric acid monoester [2-hydroxyethyl (meth) acryloyl phosphate, phenyl-2-acryloyloxyethyl phosphate, etc.] Etc. Salts of water-soluble monomers containing the above-mentioned carboxyl group, sulfonic acid group, and phosphoric acid group [for example, alkali metal salts (sodium salt, potassium salt, etc.), alkaline earth metal salts (calcium salt, magnesium salt, etc.), amine Salt or ammonium salt] and the like. Amide group-containing monomer [eg (meth) acrylamide], tertiary amino group-containing monomer [eg dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylamide], quaternary ammonium group-containing monomer [eg the above-mentioned tertiary Quaternized amino group-containing monomers (methyl chloride, dimethyl sulfate, benzyl chloride,
Quaternized using a quaternizing agent such as dimethyl carbonate), etc.], epoxy group-containing monomers [eg glycidyl (meth) acrylate], and other monomers [4-vinylpyridine, vinylimidazole, N-vinylpyrrolidone, etc. ] Etc. are mentioned.

At least one hydrolyzable group [acid anhydride group, lower alkyl (C1 to C3) ester group, nitrile group, etc.] is used as the water-soluble monomer by hydrolysis.
Radical polymerizable monomers having Examples of the radical-polymerizable monomer having an acid anhydride group include a radical-polymerizable monomer having 4 to 20 carbon atoms such as maleic anhydride, itaconic anhydride, and citraconic anhydride, and a radical-polymerizable monomer having an ester group. As the monomer, for example, lower alkyl (C1 to C3) of monoethylenically unsaturated carboxylic acid
Esters [eg, methyl (meth) acrylate, ethyl (meth) acrylate, etc.], esters of monoethylenically unsaturated alcohols [eg, vinyl acetate, acetic acid (meth)]
And the like] and the like. Examples of the radically polymerizable monomer having a nitrile group include (meth) acrylonitrile and the like. These may be hydrolyzed during the polymerization or after the polymerization, and usually they are hydrolyzed to form a salt and become water-soluble. Examples of the salt include the same salts as those described above for the salt-forming group. You may use these 2 or more types together. Of these, water-soluble monomers are preferable. Further preferred are radically polymerizable water-soluble monomers having a carboxyl group and salts thereof, particularly preferably unsaturated mono- or polycarboxylic acids and salts thereof, most preferably (meth) acrylic acid and salts thereof. .

Examples of (c) include, for example, a cross-linking agent having two or more radically polymerizable unsaturated groups, a cross-linking agent having a radically polymerizable unsaturated group and a reactive functional group, and two or more reactive functional groups. The crosslinking agent which it has is mentioned. Specific examples of the compound having two or more radically polymerizable unsaturated groups include:
N, N'-methylenebis (meth) acrylamide, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, glycerin (di or tri) acrylate, trimethylolpropane triacrylate, tri Allylamine, triallyl cyanurate,
Triallyl isocyanurate, tetraallyloxyethane, pentaerythritol triallyl ether and the like can be mentioned.

A compound having at least one functional group capable of reacting with the functional groups of (a) and (b) and having at least one radically polymerizable unsaturated group [eg hydroxyethyl (meth) acrylate, N -Methylol (meth) acrylamide, glycidyl (meth) acrylate, etc.]
Is mentioned. Specific examples of the compound having two or more functional groups capable of reacting with the functional groups (a) and (b) include polyhydric alcohols (for example, ethylene glycol, diethylene glycol, glycerin, propylene glycol, trimethylolpropane, etc.), Alkanolamines (eg,
Diethanolamine, etc.), polyamine (eg, polyethyleneimine, etc.), and the like. Two or more kinds of these crosslinking agents may be used in combination. Among these, preferred are copolymerizable cross-linking agents having two or more radically polymerizable unsaturated groups, more preferably N, N'-methylenebisacrylamide, ethylene glycol diacrylate, trimethylolpropane triacrylate, Tetraallyloxyethane, pentaerythritol triallyl ether, triallylamine. The ratios of (a), (b) and (c) and the method for producing the water absorbent resin are not particularly limited. As a specific example of the water absorbent resin, Japanese Patent Application Laid-Open No. 52-2588
No. 6, JP-B-53-46199, JP-B-53-462
No. 00 and Japanese Patent Publication No. 55-21041 are mentioned.

(2) Polymerization of (a) and (b) (hydrolyzate of starch-acrylonitrile graft polymer, hydrolyzate of cellulose-acrylonitrile graft polymer, etc.); (3) above ( (A) Crosslinked product (eg, carboxymethylcellulose crosslinked product); (4) Copolymer of (b) and (c) above (partial hydrolyzed product of crosslinked polyacrylamide, crosslinked acrylic acid-acrylamide copolymer) Polymers, crosslinked polysulfonates (crosslinked sulfonated polystyrene, etc.), crosslinked polyacrylate / polysulfonate copolymers,
Saponified vinyl ester-unsaturated carboxylic acid copolymer (JP-A-52-14689 and JP-A-52-2745)
No. 5, etc.), crosslinked polyacrylic acid (salt), crosslinked acrylic acid-acrylic acid ester copolymer, crosslinked isobutylene-maleic anhydride copolymer, crosslinked Polyvinylpyrrolidone, and crosslinked carboxylic acid-modified polyvinyl alcohol); and (5) the polymer (b) having self-crosslinking property (self-crosslinking polyacrylate, etc.); You may use together 2 or more types of the water absorbent resin illustrated above. There is no particular limitation on the type of salt and the degree of neutralization in the case of a water-absorbent resin in the form of a neutralized salt, but the type of salt is preferably an alkali metal salt, more preferably a sodium salt and a potassium salt, The degree of neutralization for acid groups is preferably 50-9.
It is 0 mol%, more preferably 60 to 80 mol%.
You may use together 2 or more types of the water absorbent resin illustrated above.

Of these water-absorbent resins (S), preferred ones are the cross-linked starch-acrylic acid graft polymer hydrolysates and cross-linked polyacrylamides among those exemplified as (1) and (4). Polymer, cross-linked acrylic acid (salt) -acrylamide copolymer, cross-linked polyacrylic acid (salt), cross-linked acrylic acid (salt) -acrylic acid ester copolymer, and cross-linked carboxylic acid modification Polyvinyl alcohol, crosslinked N-vinyl compound, crosslinked polysulfonic acid (salt), crosslinked polyacrylic acid (salt) / polysulfonic acid (salt) copolymer,
(Meth) acrylamide-N-alkyl (C1-C1
5) a cross-linked product of sulfonic acid (salt), a cross-linked product of a copolymer of (meth) acrylamide-N-alkyl (having 1 to 5 carbon atoms) sulfonic acid (salt) and (meth) acrylic acid (salt),
Further preferred are hydrolysates of cross-linked starch-acrylic acid graft polymer, cross-linked acrylic acid (salt) -acrylamide copolymer, cross-linked polyacrylic acid (salt), cross-linked polysulfonic acid ( Salt), crosslinked polyacrylic acid (salt) / polysulfonic acid (salt) copolymer, crosslinked product of (meth) acrylamide-N-alkyl (C 1-5) sulfonic acid (salt), (meth) acrylamide It is a cross-linked product of a copolymer of -N-alkyl (having 1 to 5 carbon atoms) sulfonic acid (salt) and (meth) acrylic acid (salt).

In the case of the above examples (1) and (4),
The amount of the crosslinking agent used is preferably 0.001 to 5%, more preferably 0.05 to 2%, particularly preferably 0.1 to 5%, based on the total mass of the water-soluble monomer and the crosslinking agent. 1
%. When the amount of the cross-linking agent is less than 0.001%, the water absorbing / water retaining ability, which is an important function of the water absorbent resin, becomes small, and the gel after absorbing water is likely to be in a sol state. Furthermore,
The drying property of the hydrogel polymer after polymerization is lowered, and the productivity is inefficient. On the other hand, if it exceeds 5% by mass, on the contrary, the crosslinking becomes too strong, and the water absorption / water retention capacity decreases. In addition, the water absorption speed becomes slow.

In the production of the water absorbent resin (S), the polymerization method is not particularly limited, and examples thereof include aqueous solution polymerization method, reverse phase suspension polymerization method, spray polymerization method, photoinitiated polymerization method and radiation polymerization method. . A preferred polymerization method is a method of aqueous solution polymerization using a radical polymerization initiator. In this case, the type and amount of the radical polymerization initiator used and the radical polymerization conditions are not particularly limited and can be the same as usual. If necessary, various additives, chain transfer agents (eg, thiol compounds, etc.) may be added to these polymerization systems. After drying the water-containing gel polymer of the water-absorbent resin obtained by polymerization, pulverized, and further near the surface of the absorbent particles obtained by further adjusting the particle size, the acid group such as a carboxyl group and / or its base A water-absorbent resin can also be obtained by surface-crosslinking with a crosslinking agent having at least two reactive functional groups.

Such a surface-crosslinking type water-absorbent resin is suitable for the present invention because it has excellent absorption performance and absorption rate not only under normal pressure but also under pressure and has a high gel strength. As the cross-linking agent used for the surface cross-linking, known cross-linking agents conventionally used can be applied. As a specific example, a polyglycidyl ether compound having 2 to 10 epoxy groups in one molecule [ethylene glycol diglycidyl ether, glycerin-1,3-diglycidyl ether, glycerin triglycidyl ether, polyethylene glycol (degree of polymerization 2-100) diglycidyl ether, polyglycerol (polymerization degree 2-100) polyglycidyl ether, etc.]; divalent to 20 valent polyol compound [glycerin, ethylene glycol, polyethylene glycol (polymerization degree 2-100), etc.]; 2 To 20 valent polyamine compounds (ethylenediamine, diethylenetriamine, etc.); polyamine resins having a molecular weight of 200 to 500,000 (polyamide polyamine epichlorohydrin resin,
Polyamine epichlorohydrin resin, etc.), alkylene carbonate [ethylene carbonate, etc.], aziridine compound, oxazoline compound, polyimine compound and the like. Among these, preferred are polyglycidyl ether compounds, polyamine resins and aziridine compounds in that they can be surface-crosslinked at a relatively low temperature.

The amount of the cross-linking agent in the surface cross-linking is not particularly limited because it can be variously changed depending on the kind of the cross-linking agent, the conditions for cross-linking, the target performance, etc., but is preferably 0. 001 to 3% by weight, more preferably 0.01 to 2% by weight, particularly preferably 0.05.
~ 1% by weight. When the amount of the crosslinking agent is 0.001% by weight or more, the surface crosslinking effect is exhibited. On the other hand, when the content is 3% by weight or less, the absorption performance is not deteriorated, which is preferable.

The water absorption capacity relative to the mass of the water absorbent resin (S) is preferably 10 to 1500 times, more preferably 100 to 1000 times. The shape of the water-absorbent resin is not particularly limited, but for example, granular, granular,
Granules, flakes, lumps, pearls, etc. are available. The water absorption capacity of the water absorbent resin (S) is a value obtained by measurement by the following method. <Water Absorption Capacity of Water-Absorbent Resin (S)> A water-absorbent resin sample (sample amount: Xg) was placed in a nylon net bag (250 mesh), and the whole bag was immersed in excess water. After 60 minutes of immersion, pull the bag up into the air and let it stand for 1
After draining for 5 minutes, the mass (Yg) was measured and the water absorption capacity was calculated from the following formula. [The same operation as above was performed using only the mesh bag, and the mass (Zg) of this portion was subtracted as a blank. ] Absorbed water rate = (Y−Z) / X

The average particle size of the particles is not particularly limited, but is preferably 50 to 850 μm, more preferably 60 to 400 μm. If it is larger than 50 μm, no powder leaks from the water-permeable, water-insoluble sheet (A), and it is 850 μm.
When it is less than m, the tactile sensation when the covering material is attached to the cold insulating material is good, and the water absorption rate when absorbing dew condensation water is good. The particle size distribution is not particularly limited, but is preferably 50-
It is possible to use crushed particles such that particles in the range of 850 μm are 95% by mass or more. Here, the average particle diameter means the mass average particle diameter, the mass average particle diameter, each particle size distribution of the cross-linked polymer is plotted on the logarithmic probability paper of the particle diameter on the horizontal axis, the vertical axis on the mass basis, It is measured by the method of determining the particle size at which 50% of the whole is occupied.

The water absorption rate of the water absorbent resin (S) is usually 5 to 5.
It is 400 seconds, preferably 5 to 300 seconds, more preferably 5 to 200 seconds, and particularly preferably 5 to
100 seconds. If the water absorption rate is less than 5 seconds, blocking of the water-absorbent resins with each other is likely to occur during the production of the water-absorbent sheet due to the influence of humidity in the air, resulting in poor processability. On the other hand, if the water absorption rate exceeds 400 seconds, dew condensation water will be generated on the surface of the cold insulating material, and the cold insulating effect will be shortened. When the application is a cold insulating material for perishables, it is preferably 5 to 300 seconds, more preferably 5 to 200 seconds. Water absorption rate test method: JIS K 722 except that the sample mass of the (S) is 2.00 g and the salt solution concentration is 10 mass%.
The test method based on the test method of 4-1996. That is, J
The following items were changed in the test method of IS K 7224-1996. Test solution concentration "0.900 +/- 0.
"01 M / v%" was defined as "10% by mass". Sample mass
"When the test solution is deionized water, about 0.50g, 0.9M
In the case of saline solution of / v%, about 2.00 g "
g ”. Therefore, the specific test method is as follows. 1. On the other hand, 50 mL of 10 mass% saline solution is put into a 100 mL glass beaker and stirred at 600 rpm using a magnetic stirrer (diameter (center part 8 mm, both ends 7 mm), length 30 mm and coated with fluororesin). 2. Sample 2.00 Test sample is put in the vortex at once,
Measure the time (seconds) from the time when the liquid was added to the time when the vortex disappeared and the liquid surface became horizontal, and use this as the water absorption speed.

For the purpose of further increasing the water absorption rate of the above water-absorbent resin, the fine filler (c) and the surface active agent are added at the stages of before the production of the water-absorbent resin, during the production, after the production, before the drying, after the production after drying and after the pulverization. It is preferable to add or treat the agent (d). In the case of the fine filler (c), it is more preferable to mix and mix it before drying. In the case of the surfactant (d), it is more preferable to treat the particles after drying. The fine filler (c) preferably has an apparent density of 0.5 g / cm ³ or less, more preferably 0.1 g / cm ³ or less. When it is 0.5 g / cm ³ or less, the fine filler is uniformly mixed in the gel containing the water-absorbent resin (hereinafter referred to as hydrogel), and the effect of improving the water absorption rate of the obtained cold insulating material is observed.

Here, the apparent density means, for example, ACCUP.
It is a value measured by YC 1330 PYCNOMETER, and an example of a specific measurement operation is as follows. Two chambers, that is, cell chambers, which are connected to the PYCNOMETER by valves.
er and expansion chamber, and their volumes are indicated by V (c) and V (e), respectively.
In the cell chamber, the sample mass (W) is weighed (volume is V) and the expansion chamber is used.
The valve leading to the er is closed, cellchamber
The internal pressure is fixed at P (1). Also at that time expa
The pressure of the region chamber is P (a).
Then, the valve connected to the expansion chamber is opened and the pressure P (2) that has spread to both chambers is measured. C before and after opening the valve
The sample volume is calculated from the chamber volume and pressure, and the apparent density is calculated by the following equation. Apparent density = W ÷ V = W ÷ [V (c) + V (e) × {P (a) -P (2)} ÷ {P (1) -P (2)}]

The material of the fine filler (c) is not particularly limited, and may be either organic or inorganic. Examples of organic materials include polyethylene, polypropylene, polystyrene, poly-p-xylylene, polyacrylate,
Polymethacrylate, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, fluororesin, polyacrylonitrile, polyvinyl ether, polybutadiene, polyamide, thermoplastic polyester, polycarbonate, polyphenylene oxide, polysulfone, thermoplastic polyurethane, polyethylene oxide, polypropylene oxide,
Examples thereof include polytetramethylene oxide, polyacetal, and cellulose derivatives. The thing obtained by copolymerizing 2 or more types of monomers which comprise these resins is also mentioned.
The weight average molecular weight is not particularly limited, but is preferably 10,000 or more, and more preferably 20,000 to 100,000.

Examples of the inorganic material include silicon oxide, aluminum oxide, iron oxide, titanium oxide, magnesium oxide, zirconium oxide and the like. The fine filler (c) is more preferably a thermally expandable hollow filler (c1). As such, for example,
A micro hollow resin containing a gas or a volatile compound in the voids may be mentioned. As the type of resin forming the outer wall in this micro hollow resin, the same as the above-mentioned organic material can be mentioned. Among these kinds of resins, preferred are polyacrylate, polyvinylidene chloride, and polyacrylonitrile.

The expansion start temperature of (c1) can be variously changed depending on the softening temperature of the resin forming the outer wall, the type of gas present in the voids, and the type of volatile compounds, but preferably 60 to 150 ° C. On the other hand, the maximum expansion temperature is preferably 80 to 180 ° C. Particularly preferably, the expansion start temperature is 70 to 120 ° C. and the maximum expansion temperature is 9
It is 0 to 150 ° C. When the expansion start temperature is lower than 60 ° C, cooling of the hydrous gel may be necessary, which is inefficient. On the other hand, when the expansion start temperature is higher than 150 ° C., water evaporation of the water-absorbent resin in the water-containing gel state progresses in advance in the heating and drying step, so that the flexibility of the water-containing gel is increased when (c1) starts expansion. As a result, the expansion efficiency may decrease. Even when the maximum expansion temperature is lower than 90 ° C. or higher than 180 ° C., the same phenomenon as described above may occur, which is not preferable.

As an example of the gas or volatile compound contained in the void of (c1), the boiling point at atmospheric pressure is preferably 150 ° C. or lower, more preferably 120 ° C.
The following compounds are particularly preferable at 100 ° C. or lower. When the boiling point is 150 ° C. or lower, the thermal expansion start temperature of (c1) is not too high, which is economical. Further, the thermal expansion is sufficient, and the effect of improving the water absorption rate of the obtained cold insulating material becomes good. (C
As the gas or volatile compound contained in the void of 1),
For example, isobutane, isopentane, petroleum ether, n
-Butane, n-pentane, n-hexane, cyclopentane, cyclohexane, trichlorofluoromethane, dichlorofluoromethane, butylene, methylene chloride and the like can be mentioned. You may use these 2 or more types together. Preferred are isobutane, isopentane, n-butane, n-pentane, petroleum ether. The volume expansion ratio of (c1) is preferably 10 times or more. More preferably, it is 30 times or more. When the volume expansion ratio of (c1) is less than 10 times, the expansion coefficient of (S) is low, so that the effect of improving the water absorption rate of the obtained cold insulating material may be poor. Specific examples of (c1) include, for example, Matsumoto Yushi-Seiyaku Co., Ltd. Matsumoto Microspheres F-20, F-30, F-40, F-.
50, F-80S, F-82, F-85, F-100,
F-30VS, F-80GS, F-80VS, F-10
0SS, F-1300, F-1400, Nippon Ferrite Co., Ltd. Expancel 820, 642, 551,
461, 051, 091 and the like can be mentioned, and these may be used in combination of two or more kinds.

The blending amount of (c) with respect to (S) is preferably 0.05 to 10% by mass. It is more preferably 0.1 to 7%, and particularly preferably 0.5 to 5%. When the addition amount is 0.05% or more, the effect of improving the water absorption rate is observed, while when it is 10% or less, the water absorption rate is improved and the mechanical strength of the water absorbent resin particles is not weakened.

The component (c) is blended at any stage before the polymerization of the water-absorbent resin, that is, from the stage of adjusting the raw materials for polymerization to the stage of drying. Preferably, the method is to add to the hydrogel polymer at the stage after polymerization until before drying and knead. This is because the water-absorbent resin in the water-containing gel state has appropriate flexibility to expand, and can further be expanded in volume by heating in the subsequent drying step to increase the surface area. The fine filler can be added in any form of powder, water slurry, and water dispersion, but in order to increase the uniform expansion and the effect of improving the water absorption rate of the obtained cold insulating material, the water slurry or the water dispersion is used. It is preferable to add it as a liquid and add it uniformly into the hydrous gel. Further, the water content of the mixture of the water-absorbent resin hydrogel and the fine filler is 2 to the solid content of the water-absorbent resin.
It is preferably 10 times.

A conventionally known device can be used as a kneading device for blending (c) with the water-absorbent resin in a water-containing gel state and uniformly dispersing it. Specific examples of the apparatus include a double-arm kneader, an internal mixer (Banbury mixer), a self-cleaning mixer, a gear compounder, a screw extruder, a screw kneader, a mincing machine, and the like. These can also be used in combination. The heat-drying temperature of the hydrous gel-like composition to which the water absorbent resin is added is preferably 60 to 230 ° C, more preferably 100 to 200.
C., particularly preferably 105 to 180.degree. When the drying temperature is 60 ° C or higher, it is economical because the drying time does not become long. On the other hand, when it is 230 ° C or lower, side reactions and decomposition of resin do not occur, and the water absorption performance and the water absorption speed decrease. Do not invite.

The apparatus for drying the mixture of the water-absorbent resin in the water-containing gel state and (c) may be an ordinary apparatus, for example, a drum dryer, a parallel flow band dryer (tunnel dryer), an aeration band dryer. , A jet flow (nozzle jet) dryer, a box-type hot air dryer, an infrared dryer and the like. When a combustible compound is contained in the void portion of (c), a direct-fire type heat source is not preferable, but in the case of a nonflammable compound, the heat source is not particularly limited. These dryers may be used in combination.

The average particle diameter (Nassenstein diameter) of the fine filler (c) is smaller than the particle diameter of (S), preferably 0.001 to 200 μm, more preferably 0.00.
5 to 150 μm, particularly preferably 0.01 to 100 μm
Is. Further, the particle size of (c) in 0.0005 to 200 μm is preferably 90% or more by mass, particularly preferably 95% or more, and the average particle size of (c) is 2
When the thickness is 00 μm or less, a large addition amount is not required to improve the drying property, which is economical. Furthermore, the performance of the resulting water absorbent resin is not deteriorated, which is preferable. On the other hand, 0.001 μm
The above is preferable because aggregation of (c) hardly occurs and a uniform distribution is likely to occur and the drying property is not deteriorated.
To measure the average particle size, the inspection sample is 50-100 m in the dispersion medium.
g, ultrasonic waves are applied for 60 seconds, and then measured using a SK laser particle size distribution measuring device (manufactured by Seishin Enterprise Co., Ltd.). (C)
The shape is not particularly limited, and examples thereof include crushed shape, hollow shape, porous shape, petal shape, and granulated shape. Preferred shapes are crushed and porous.

As the surfactant (d) to be treated, nonionic surfactant (d1), anionic surfactant (d2), cationic surfactant (d3), amphoteric surfactant (d4). Is mentioned. Specific examples of the nonionic surfactant (d1) include an aliphatic alcohol (having 8 to 24 carbon atoms) and an alkylene oxide (having 2 carbon atoms).
To 8) adduct (degree of polymerization = 1 to 100) [lauryl alcohol ethylene oxide addition (degree of polymerization = 20), oleyl alcohol ethylene oxide addition (degree of polymerization = 1)
0) product, Macco alcohol ethylene oxide addition product (polymerization degree = 35), etc.], polyoxyalkylene (C2-8, polymerization degree = 1-100) higher fatty acid (C8
To 24) ester [polyethylene glycol monostearate (polymerization degree = 20), polyethylene glycol distearate (polymerization degree = 30), etc.], polyvalent (divalent to 10 valent or higher) alcohol fatty acid (having 8 to 24 carbon atoms) )
Ester [Glycerin monostearate, ethylene glycol monostearate, sorbitan lauric acid (mono / di) ester, sorbitan palmitic acid (mono / di)
Ester, sorbitan stearic acid (mono / di) ester, sorbitan oleic acid (mono / di) ester, sorbitan coconut oil (mono / di) ester, etc.], polyoxyalkylene (carbon number 2 to 8, degree of polymerization = 1 to 100) ) Polyhydric (divalent to 10 valent or higher) alcohol higher fatty acid (C8 to C24) ester [polyoxyethylene (degree of polymerization = 10) sorbitan lauric acid (mono / di) ester, polyoxyethylene (degree of polymerization) = 20) sorbitan palmitic acid (mono / di) ester, polyoxyethylene (polymerization degree = 15) sorbitan stearic acid (mono / di)
Ester, polyoxyethylene (degree of polymerization = 10) sorbitan oleic acid (mono / di) ester, polyoxyethylene (degree of polymerization = 25) lauric acid (mono / di) ester, polyoxyethylene (degree of polymerization = 50) stearic acid (Mono / di) ester, polyoxyethylene (degree of polymerization =
18) Oleic acid (mono / di) ester, sorbitan,
Polyoxyethylene (degree of polymerization = 50) Dioleic acid methyl glucoside, etc.], fatty acid alkanolamide [1: 1
Type coconut oil fatty acid diethanolamide, 1: 1 type lauric acid diethanolamide, etc.], polyoxyalkylene (C2-8, degree of polymerization = 1-100) alkyl (C1
To 22) phenyl ether (polyoxyethylene (degree of polymerization = 20) nonylphenyl ether, etc.), polyoxyalkylene (having 2 to 8 carbon atoms, degree of polymerization = 1 to 100) alkyl (having 8 to 24 carbon atoms) amino ether and alkyl (C8-24) dialkyl (C1-6) amine oxide [lauryldimethylamine oxide, etc.], polydimethylsiloxane polyoxyethylene adduct, polyoxyethylene / polyoxypropylene block polymer (weight average molecular weight = 150- 10000) and the like.

As the anionic surfactant (d2),
Hydrocarbon-based ether carboxylic acids having 8 to 24 carbon atoms or salts thereof, [polyoxyethylene (degree of polymerization = 1 to 100)
Sodium lauryl ether acetate, polyoxyethylene (degree of polymerization = 1 to 100) disodium lauryl sulfosuccinate, etc., C8-24 hydrocarbon sulfate salt [sodium lauryl sulfate, degree of polymerization (degree of polymerization = 1 to 100) 100) sodium lauryl sulfate, polyoxyethylene (degree of polymerization = 1 to 100) triethanolamine lauryl sulfate, polyoxyethylene (degree of polymerization = 1 to 1)
00) coconut oil fatty acid monoethanolamide sodium sulfate,], a hydrocarbon sulfonate having 8 to 24 carbon atoms [sodium dodecylbenzenesulfonate, etc.] and 8 carbon atoms
To 24 hydrocarbon phosphate salts [sodium lauryl phosphate, polyoxyethylene (degree of polymerization = 1 to 10
0) sodium lauryl ether phosphate, etc.], fatty acid salt [sodium laurate, triethanolamine laurate, etc.], acylated amino acid salt [sodium coconut oil fatty acid methyl taurine, sodium coconut oil fatty acid sarcosine sodium, coconut oil fatty acid sarcosine triethanolamine , N
-Coconut oil fatty acid acyl-L-glutamic acid triethanolamine, N-coconut oil fatty acid acyl-L-glutamate sodium, lauroylmethyl-β-alanine sodium, etc.], and others [polyoxyethylene sulfosuccinate (degree of polymerization = 1 to 100) Lauroyl ethanolamide 2
Sodium and the like] and the like. Examples of the cationic surfactant (d3) include a quaternary ammonium salt type [stearyl trimethyl ammonium chloride, behenyl trimethyl ammonium chloride, distearyl dimethyl ammonium chloride, lanolin fatty acid aminopropylethyl dimethyl ammonium sulphate], an amine salt type [ Stearic acid diethylaminoethylamide lactate, dilaurylamine hydrochloride, oleylamine lactate, etc.] and the like.

Examples of the amphoteric surfactant (d4) include betaine-type amphoteric surfactants [coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-
Hydroxyethyl imidazolinium betaine, lauryl hydroxysulfobetaine, lauroylamidoethyl hydroxyethyl carboxymethyl betaine hydroxypropyl sodium phosphate, etc.], and an amino acid type amphoteric surfactant [sodium β-lauryl aminopropionate etc.] can be mentioned. One or more of these surfactants can be used. Among these, nonionic surfactants (d
1) and the anionic surfactant (d2) are preferred. By using the surfactant together, the effect of improving the water absorption rate of the cold insulating material can be more remarkably exhibited.

The amount of (d) added to the water-absorbent resin (S) can be variously changed depending on the nature of (S) and the amount of (d) added, but is preferably the mass of the solid content of (S). On the other hand, 0.005 to 1%, more preferably 0.
It is 01 to 0.7%. When the addition amount is 0.005% or more, the effect of improving the drying property is exhibited. On the other hand, when the content is 1% or less, the powder fluidity of the dried product is not adversely affected, and the powder handling property as the water absorbent resin is good. The reason why the combination of (c) and (d) improves the drying property and the water absorption rate is that (d) functions to help the uniform dispersion of (c), and at the same time, a hydrophilic group and a hydrophobic group are added. It is presumed that since the hydrophilic group of the surfactant contained has affinity with (A), the hydrophobic group is oriented outward and the effect of preventing gel fusion is improved.

The method of adding and mixing (d) to (S) is not particularly limited. It is preferable to disperse (c) and (d) in water and / or a solvent and then add and mix them, because uniform mixing is possible. When the components (c) and (d) are dispersed in water and / or a solvent, the concentration is suitably 0.01 to 50% by mass. More preferably, it is 0.1 to 30%. If the concentration is 0.01% or more and the amount of (c) added to (S) increases, the amount of water and / or solvent in (S) does not increase and the drying efficiency does not deteriorate. If it is 50% or less, (c)
Further, the viscosity of the solution (d) does not increase and the handling is easy, and the mixing with (S) is uniform, and the drying property improving effect is exhibited. The solvent is not limited as long as (c) and (d) can be dispersed, but a solvent having a low boiling point up to 100 ° C is preferable. Specific examples include alcohols (methanol, ethanol, isopropanol, etc.), ketones (acetone, methyl ethyl ketone, diethyl ketone, etc.), esters (methyl acetate, ethyl acetate, isopropyl acetate, etc.).

The method of adding and mixing water and / or a solvent dispersion of (c) and (d) to (S) is carried out by spraying or pumping before, during or after shredding of (S). There is a method of sprinkling it using the like. A method is preferable in which (S) is shredded after shredding and (c) and (d) are dispersed and mixed as uniformly as possible on the surface of (S) during gel transfer to a dryer. When the gel is kneaded with a large shear after sprinkling the dispersion liquid, the dispersion liquid is kneaded even into the inside of (S), the addition effect is weakened, and a large addition amount is required, which is uneconomical. Shred (S),
Further, as a device used for blending (S), (c) and (d), a conventionally known device can be used,
The same as above can be used.

One form of the coating material of the present invention is formed by enclosing and sealing the water-absorbent sheet (B) in the water-permeable and water-insoluble sheet (A). The encapsulation form is not particularly limited, and examples thereof include a method of forming (A) into a bag shape. The method for manufacturing the covering material is not particularly limited. When (A) is formed into a bag shape, the bag may be formed into a bag shape by stacking two sheets of (A) and sealing them or by stacking three or more sheets of (A). It is also possible to put (B) in a bag-shaped product from the beginning when a part thereof is opened and then seal the opened part to form a bag. As a method of making a bag, after sealing a part of (A), inserting (B) and then sealing the remaining part, placing (B) on (A) and sealing around it Methods and the like. The sealing method is not particularly limited as long as it is sealed so that the sealing portion does not come off during transportation or handling of the covering material,
Usually, heat sealing (heat fusion), pressure bonding or the like is performed. The temperature for heat fusion is preferably 50 to 300 ° C, more preferably 70 to 200 ° C. The pressure of pressure bonding is preferably 0.1 to 10 kg / cm ² , and more preferably 0.1.
It is 5 to 5 kg / cm ² . Of these, heat sealing is preferable. Heat sealing is usually performed under pressure. The conditions may be the same as above. A seal material may be used for at least a part of the seal. The sealing is performed by interposing a sealing material between the sheets. The adhesive strength of the sheet is preferably 0.1 kgf / 25 mm or more, more preferably 0.2 kgf / 25 mm or more. Adhesion may be performed so that the sealing portion does not come off during transportation or handling of the covering material. The adhesive strength can be measured by the following method. [Adhesive strength] Peel strength (180 ° C peel strength, tensile speed 100 mm / min, unit; k
gf / 25 mm) is measured.

In the present invention, when a cold insulating medium is enclosed in a container made of a water impermeable substrate to obtain a cold insulating material, the water impermeable substrate and the cold insulating medium are not particularly limited, and they are conventionally used. The water-impermeable base material of the existing cold-insulating material and the cold-insulating medium, for example, the following are mentioned. The water-impermeable substrate is not limited as long as it is a flexible and water-impermeable film, but it is a synthetic resin film such as polyester film, nylon, polyethylene film, polypropylene film; laminated laminate film thereof; aluminum foil And the like, and a multilayer laminate film of a synthetic resin film and a metal film. From the viewpoint of flexibility, a synthetic resin film and a laminated laminate film of synthetic films are preferable.

As the medium for keeping cold, a conventionally known medium can be used, and examples thereof include (1) to (4). (1) A flexible gel-like material in which a water-soluble polymer is dissolved in water. As the water-soluble polymer, the weight average molecular weight is not particularly limited as long as it is water-soluble, but the weight average molecular weight is usually 1,000 to
1,000,000, preferably 2000 to 500,000, and particularly preferably 5000 to 200,000. When the weight average molecular weight is less than 1,000, the gelling effect of the aqueous solution is weak, and when it exceeds 1,000,000, it is difficult to dissolve in water and the gelling time is delayed. Specific examples that can be used include natural polymers, semi-synthetic polymers, and synthetic polymers. Examples of natural polymers include starchy substances (starch, etc.); animal proteins (gelatin, casein, colagen, etc.); animal proteins (soy protein, wheat protein, etc.);
Fibrin (wood cellulose, etc.); Seaweed extract (agar, carrageenan, etc.); Plant seed mucilage (guar gum, locust bean gum, tamarind seed gum, etc.); Plant tree mucilage (acacia, tragacanth, etc.) Pesticides (pectin, etc.); Microbiologically produced mucilages (xanthan gum, pullulan, curdlan, dextran, julan gum, etc.); Plant rhizome mucilages (konjac mannan, etc.) and the like. Examples of the semi-synthetic polymer include cellulose derivatives (methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, carboxymethyl cellulose, methyl hydroxypropyl cellulose, etc.); starch derivatives (soluble starch, carboxymethyl starch, methyl starch, etc.);
In addition, alginic acid derivatives (alginate, propylene glycol alginate, etc.) and the like can be mentioned.

As the synthetic polymer, polyoxyalkylene compound (1a), vinyl resin [acrylic resin (1
b), polyvinyl alcohol, polyvinylpyrrolidone,
Polyvinyl methyl ether, carboxy vinyl polymer], isobutylene-maleic anhydride copolymer and the like. Among the synthetic polymers, examples of the polyoxyalkylene compound (1a) include polyethylene glycol, alkylene oxide (ethylene oxide, propylene oxide, etc.) adducts of polyhydric alcohols, polyoxyethylene / oxypropylene glycol (ethylene oxide and propylene oxide). And the same polyethers used for producing the urethane resin described later.

Acrylic resin (1b) among synthetic polymers
Examples include (meth) acrylamide, (meth) acrylic acid (salt) [for example, sodium acrylate, etc.], 2-alkyl-2-acrylamidopropanesulfonic acid (salt)
[2-alkyl-2-acrylamidopropanesulfonic acid sodium salt, etc.], (meth) acryloyloxyalkylammonium quaternary salt [eg methacryloyloxyethyltrimethylammonium chloride, etc.], (meth) acryloyloxyalkyldialkylamine salt [eg , A tertiary or quaternary salt of diethylaminoethyl methacrylate, etc.] is a polymer having a constitutional unit of at least one vinyl monomer selected from the group consisting of poly (meth) acrylamide and poly (meth). Acrylic acid (salt), (meth) acrylic acid (salt) and (meth)
Copolymer with acrylamide, acrylic acid-acrylic acid ester copolymer, partial hydrolyzate of poly (meth) acrylamide, (meth) acrylic acid (salt), (meth) acrylamide and 2-acrylamido-2-methylpropane Ternary copolymer with sulfonic acid (salt) or vinyl sulfonic acid (salt), poly (meth) acryloyloxyethyltrimethylammonium chloride, (meth) acrylamide and (meth) acryloyloxyethyltrimethylammonium quaternary salt And the like. As the above-mentioned salts, alkali metal salts such as sodium and potassium, amine salts such as ammonia and trimethylamine are preferable.

(2) A gel of the above water-absorbent resin, which absorbs water or a mixed solvent containing water as a main component. (3) Freezing point depressants (polyhydric alcohols, urea, ammonium nitrate, etc.) on the gel-like material of (1) or (2) above
Cooling medium to which is added. (4) Substances that absorb heat when dissolved in water (urea, ammonium nitrate, sodium nitrate, sodium carbonate decahydrate, diammonium phosphate, sodium tetraborate decahydrate, sodium thiosulfate decahydrate, etc.) and water-soluble organic polymers Alternatively, a two-component cold storage medium comprising water to which a water absorbent resin is added. If necessary, an antiseptic agent, an antifungal agent, an antioxidant, an ultraviolet absorber, etc. may be added to the cold insulating medium.

An example of a method of manufacturing the cold insulating material will be described below with reference to the drawings. First, as shown in FIG. 2, a mixture of the water-absorbent resin 5 and the paper pulp 8 is evenly dispersed on the tissue paper 7, then the other tissue paper 7 is overlapped, and further pressure molding such as embossing is performed. Then, the water absorbing sheet 10 is manufactured. Next, the water-permeable and water-insoluble sheet 9
Was heat-sealed on three sides to prepare a bag-shaped product having an open part, and then the laminated sheet was put therein, and the open part was sealed to form a sheet. Further, both sides of the sheet were heat-sealed to prepare a bag-shaped covering material 6 with a part thereof opened as shown in FIG. A cold insulating material 7 obtained by enclosing a cold insulating medium in a container made of an impermeable base material is inserted into a bag of this covering material, and one side of the bag is adhered to the outside of the other bag with a double-sided adhesive tape 11. The cold insulating material of the present invention was produced.

The present invention will be further described below with reference to examples, but the present invention is not limited thereto. The following parts indicate parts by mass.

Production Example 1 200 g of acrylic acid and 0.6 g of pentaerythritol triallyl ether (manufactured by Daiso) in a 2 L beaker.
(0.3% / acrylic acid) and 800 g of ion-exchanged water were added and cooled to 8 ° C. Aqueous acrylic acid solution was placed in a 1.5-liter adiabatic polymerization tank, and nitrogen was passed through the solution to make the amount of dissolved oxygen in the solution 0.1 ppm or less, and 4.0 g of 0.1% hydrogen peroxide solution and 0.1% L were added. -4.0 g of ascorbic acid aqueous solution and 2,2'-azobis (2-amidinopropane) hydrochloride (manufactured by Wako Pure Chemical Industries, Ltd., trade name:
1.0 g of a 10% aqueous solution of V-5) was added, and nitrogen purging into the aqueous solution was continued until the polymerization started. Since the polymerization started and the viscosity of the acrylic acid aqueous solution started to increase, the nitrogen purge was stopped and the polymerization was carried out for 6 hours. When the temperature of the acrylic acid aqueous solution was measured with a dot-spot thermometer, the highest temperature reached was 63 ° C. In the above polymerization, the average degree of polymerization of the polymer excluding the cross-linking agent pentaerythritol triallyl ether was measured using GPC, and the average degree of polymerization of the polymer was about 28,000. The block-shaped cross-linked hydrogel was taken out from the adiabatic polymerization tank, and the gel was subdivided into 3 to 10 mm using a small meat chopper (manufactured by Royal Co.), and then 222 g of a 40% aqueous solution of sodium hydroxide (special grade reagent) ( Neutralization degree 8
0 mol%) was added to neutralize the hydrous gel. The neutralized water-containing gel was laminated on a SUS screen with an opening of 850 microns to a thickness of 5 cm, and hot air at 120 ° C. was used for 1 with a small air dryer (Inoue Metal Co., Ltd.). The hydrogel was allowed to permeate for a period of time to dry the hydrogel. Aerosil No. is added to 100 parts of the dried product. 200 (manufactured by Nippon Aerosil Co., Ltd.) 2.5
Grind the mixture of parts using a cooking mixer,
A crushed product was obtained. This pulverized product is 106-4 with a sieve.
25 μm (JIS: 36 mesh to JIS: 100 mesh) particles having a particle size of 245 μm
A water absorbent resin (1) (water absorption rate: 180 seconds) (manufactured by Nikkiso Co., Ltd., trade name: measured by Microtrac FRA particle size analyzer, the same applies hereinafter) was obtained.

Production Example 2 77 g of sodium acrylate, 22.8 g of acrylic acid, 0.2 g of N, N'-methylenebisacrylamide and 295 g of deionized water were placed in a glass reaction vessel having a volume of 1 liter.
The temperature of the contents was maintained at 3 ° C. while charging, stirring and mixing. After nitrogen was introduced into the contents to adjust the amount of dissolved oxygen to 1 ppm or less, 1 g of a 1% aqueous solution of hydrogen peroxide, 1.2 g of a 0.2% aqueous solution of ascorbic acid and 2,2'-azobisamidinopropanedihydro. A hydrated gel-like polymer (S1) was obtained by adding and mixing 2.8 g of a 2% aqueous solution of chloride to initiate polymerization and polymerizing for about 5 hours. The resulting hydrogel of (S1) was mixed with an internal mixer for 3
Expansell 091D after shredding to ~ 7mm
E (apparent density = 0.03 g / cm3; particle size 50-80)
100 μg of 2% aqueous dispersion of 100 μm), further uniformly mixed with an internal mixer, and then dried with an aeration band dryer (manufactured by Inoue Metal Industry Co., Ltd.) under the conditions of 150 ° C. and a wind speed of 2.0 m / sec. . The obtained dried product was crushed to prepare Production Example 1
It was pulverized in the same manner as above and sieved to obtain a water absorbent resin (2) having an average particle size of 60 μm (water absorption rate: 28 seconds).

Production Example 3 The hydrogel of (S1) obtained in Production Example 2 was shredded to a size of 3 to 7 mm with an internal mixer, and then "Matsumoto Microsphere F-30" (expansion start temperature 85 to 9
0 ℃, maximum expansion temperature 130-140 ℃, expansion ratio about 72
10% of a 20% aqueous dispersion of 10 times) and further uniformly mixed by an internal mixer, and then 150 ° C., wind speed 2.
It was dried with a ventilation type band dryer (manufactured by Inoue Metal Industry) under the condition of 0 m / sec. The obtained dried product was pulverized, pulverized in the same manner as in Production Example 1, and sieved to obtain a water absorbent resin (3) having an average particle size of 90 μm (water absorption rate: 20 seconds).

Production Example 4 The hydrogel of (S1) obtained in Production Example 2 was shredded to a size of 3 to 7 mm with an internal mixer, and then expanded with Expancel 091 DE (apparent density = 0.03 g / cm3; granules). 100 g of a 2% aqueous dispersion having a diameter of 50 to 80 μm) is added,
Further, the water-containing gel polymer (S2) uniformly mixed with an internal mixer is used for a length of 3 to 3 with a screw type extruder.
After cutting into a cylindrical shape with a size of 7 mm, Emulmin 86
2 (manufactured by Sanyo Kasei Co., Ltd., polyethylene diglycol distearate) 2 g and a mixed solution of 60 g tap water (S
2% was added to the solid content of 2) and passed through the internal mixer again, and this was laminated to a thickness of about 5 cm, and the ventilation band dryer was operated under the conditions of 140 ° C. and a wind speed of 2.0 m / sec. (Made by Inoue Metal) and dried. The obtained dried product (water content: 5.0%) was crushed and sieved to obtain an average particle size of 90 μm.
Water-absorbent resin (4) (water absorption rate: 14 seconds) was obtained.

Example 1 [Preparation of water absorbing sheet] Water absorbing resin Sunfresh ST-
A material obtained by dry-blending 500D (200 parts) and paper pulp (100 parts), only uniformly sprayed can at a rate of 40 g / m ² on the basis weight of 30 g / m ² tissue paper, to which homogeneous Stack the tissue paper on the upper side, fix the water-absorbent resin and the paper pulp between the two pieces of tissue paper through the embossing roll, and set the width 23c.
A water absorbing sheet having a length of m and a length of 39 cm was obtained. Sunfresh ST-500D: Polyacrylic acid cross-linking type water absorbent resin, water absorption capacity 400 times, particle size 106 to 850 μm, average particle size 3
70 μm, water absorption speed 340 seconds; manufactured by Sanyo Kasei Co., Ltd.

[Preparation of packaging material] As the water-permeable and water-insoluble sheet, a polyethylene / polypropylene mixed-spun non-woven fabric having a width of 30 cm and a length of 45 cm (weight per unit area: 25 g / m2) was used, and the water-absorbent sheet was placed at the center of the sheet. Place the water-insoluble sheets of the same quality and the same size on top of each other, heat-seal each side with a width of 5 mm, then fold at one-third from both sides, and overlap the overlapping sides by 5 mm.
The bag was heat-sealed with a width to create a bag-shaped packaging material with an open part.

[Creation of Cooling Material] As a water impermeable sheet,
A polyethylene film having a width of 25 cm and a length of 32 cm (thickness: 80 μm) was used, folded in two, and the two sides were heat-sealed to prepare a cold insulating material container. Into this container, a gel-like cold insulating medium composed of water-absorbent resin Sun Fresh ST-500D (10 g), carboxymethyl cellulose (2 g) and water 988 cc was put, and the opening was heat-sealed to prepare a cold insulating material. This cold insulating material was inserted into the above packaging material, one end of the packaging material and the outside of the bag of the packaging material were adhered to each other with a double-sided tape, and the cold insulating material of the present invention was prepared by covering the cold insulating material with the packaging material.

Example 2 [Preparation of Water Absorption Sheet] Water-absorbent resin Sunfresh S is applied to the adhesive surface of cellophane tape having a width of 23 cm and a length of 39 cm (the base material is a cellulose film and the adhesive is an acrylic resin).
T-500D was sprinkled, pressed by a roll, and then Sunfresh ST-500D, which was not fixed, was shaken off to obtain a water absorbent sheet. The fixed amount at this time is 40 g / m
^{Was 2} . [Preparation of packaging material] A packaging material was prepared in the same manner as in [Preparation of packaging material] of Example 1 except that the water absorbing sheet of Example 2 was used instead of the water absorbing sheet of Example 1. [Preparation of cold insulation material] The present invention in which the cold insulation material of Example 1 is inserted into the above packaging material, one end of the packaging material and the outside of the bag of the packaging material are adhered to each other with a double-sided tape, and the cold insulation material is covered with the packaging material. I made a cold insulator.

Examples 3 to 6 In the same manner as in Example 1 except that the water absorbent resins (1) to (4) obtained in Production Examples 1 to 4 were used instead of the Sunfresh ST-500D, a cold insulating material was prepared. Created. Comparative Example 1 In [Preparation of cold insulating material] of Example 1, a cold insulating material not covered with a packaging material was used. Comparative Example 2 Instead of the cold insulating material of Example 1, dry ice (1 kg) was used. Comparative Example 3 In Production Example 1, the pulverized material was sieved to 1,000
The same operation as in Production Example 1 was carried out except that particles having a particle size of ˜1,400 μm (JIS; 12 mesh to 16 mesh) were sampled, the average particle size was 1,200 μm, and the water absorption rate was 750.
Second comparative water absorbent resin (i) was obtained.

The test method for the cold insulating material is shown below. <Cooling effect confirmation test> The cold insulating material was completely frozen at -40 ° C. Insert this cold insulator between the comforter and comforter in the test container, close the lid and leave it in the room for about 48 hours.
The surface temperature of the cold insulating material was measured. At the same time, the generation state of dew condensation water (the surface of the cold insulating material, the outer surface of the test container) was visually observed. Test container: Wooden box with lid (using a flat plate with a thickness of 2 cm,
30 cm wide, 60 cm wide, 20 cm high) with a cotton blanket (10 cm thick, 30 cm long, 60 cm wide), and a cotton comforter (5 cm thick, 30 cm long)
60 cm) was placed.

Performance Evaluation The cold insulating materials of Examples 1 to 6 and the cold insulating materials of Comparative Examples 1 to 3 were subjected to a test for confirming the cold insulating effect. The results are shown in Table 1 (confirming the dew condensation state on the outer surface of the test container) and Table 2 (confirming the dew condensation state on the surface of the cold insulating material and the cooling effect).

[0060]

[Table 1]

[0061]

[Table 2]

[0062]

The cold insulating material of the present invention has the following effects. (1) It is economical because the cold insulating material can be repeatedly used. A drip (meat juice) generated from meat by covering a cold insulating material in which a cold insulating medium is enclosed in a container made of an impermeable base material with a packaging material having water absorption and water retention properties.
It absorbs drip etc. generated from the body and the body and is contaminated,
By changing the packaging material, repeated use can be easily performed. (2) Generation of dew condensation water can be prevented. Condensation generated by the water-absorbent resin layer in the coating material provided on the surface of the cold insulating material is immediately absorbed and retained to prevent dew condensation. As a result, articles that you want to keep cool, such as fresh vegetables, fish and shellfish, livestock meat, and dairy products, do not get wet with dew condensation water, so the freshness is maintained, and bodies and the like do not get wet with dew condensation water, which may impair the appearance. Absent. Also, there is no concern that the strength of the container in which the product to be kept cool is packed will be reduced by dew condensation water. Furthermore, there is no fear that dew condensation water will cause peeling of the label attached to the cold-insulated product or bleeding of the printed matter on the label surface.

(3) Drip (meat juice) generated from meat such as fresh fish meat can be absorbed. When fresh fish raw meat or the like cooled to a temperature below the freezing point is thawed, free water from the protein tissue destroyed by freezing contains a soluble component to generate a drip, which makes the appearance extremely unsightly. Since the water-absorbent resin layer in the packaging material provided on the surface of the cold insulating material of the present invention absorbs the drip, the appearance of fresh raw fish meat or the like is not impaired. (4) Cooling duration is extended. As a result of the water-absorbent resin layer in the packaging material that has absorbed dew condensation water and drip appropriately suppressing heat conduction, it becomes possible to extend the cold-keeping duration of the cold-insulating material. It is difficult to frequently replace the cold insulation material for keeping the body cold, and it is necessary to match the conventional dry ice replacement time. The cold insulating material of the present invention can be used at the same time as the dry ice replacement time due to the extended cold insulating time, and does not cause the body to rot.

[0064]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a water retention material of the present invention.

FIG. 2 is a perspective view showing a water absorbent sheet of the present invention.

FIG. 3 is a cross-sectional view showing the water absorbent sheet of FIG.

FIG. 4 is a perspective view showing a water absorbent sheet of the present invention.

5 is a cross-sectional view showing the water absorbent sheet of FIG.

FIG. 6 is a perspective view showing a packaging material of the present invention.

7 is a cross-sectional view showing the packaging material of FIG.

[0065]

[Explanation of symbols] 1. Cooling medium 2. Impermeable sheet 3. Air layer 4. Packaging material 5. Water absorbent resin 6. Double-sided adhesive sheet 7. Tissue paper 8. Paper pulp 9. Water-permeable insoluble sheet 10. Water absorbent sheet 11. Double-sided adhesive tape 12. Turn back 13. Heat seal

Continued front page    (72) Inventor Yoji Fujiura             1 Sanyo 1-11, Hitotsubashi-honcho, Higashiyama-ku, Kyoto             Kasei Industry Co., Ltd. F-term (reference) 3E067 AB99 BA12A BA17A BB06A                       BB14A CA08 CA09 CA24                       CA30 EA06 EE28 GA01 GB09

Claims (13)

[Claims] 1. A cold insulating material obtained by enclosing a cold insulating medium in a container made of an impermeable base material, wherein the following packaging material is provided on a part or all of the outer surface of the cold insulating material. Cooling material. Packaging material: a sheet obtained by wrapping a water-absorbent sheet (B) made of a water-absorbent resin (S) in a water-permeable water-insoluble sheet (A) and sealing the water-absorbent sheet according to the following water-absorption rate test method of the (S). Is a sheet of 5 to 400 seconds. Water absorption rate test method: JIS K 722 except that the sample weight of the (S) is 2.00 g and the salt solution concentration is 10% by weight.
The test method based on the test method of 4-1996. 2. The cold insulating material according to claim 1, wherein the (S) is a mixture of (S) with a fine filler (c). 3. The (S) is the same as the (c) in the (S).
The cold insulating material according to claim 2, wherein the cold insulator is built in. 4. The apparent density of (c) is 0.5 g / c.
The cold insulating material according to claim 2 or 3, which has a m ³ or less. 5. The cold insulating material according to claim 1, wherein the (S) is treated with a surfactant (d). 6. The (S) has an average particle size of 50 to 85.
The cold insulating material according to claim 1, which has a thickness of 0 μm. 7. The method according to claim 1, wherein the (A) is a non-woven fabric.
The cold insulating material according to any one of 1. 8. The (B) comprises a base material and the (S), and a pressure-sensitive adhesive or a binder resin is used if necessary (S) between one or both sides of the base material or between two base materials. The cold insulating material according to any one of claims 1 to 7, which is fixed by fixing. 9. The cold insulating material according to claim 1, wherein the base material of (B) is one or more selected from a plastic film, cloth and paper. 10. The cold insulating material according to claim 1, wherein the base material (B) is a plastics film coated with an adhesive. 11. A refrigerating agent for funeral services, claims 1 to 1.
The cold insulating material according to any one of 0. 12. The cold insulating material according to claim 11, wherein the water absorption rate of (S) is 5 to 300 seconds. 13. The water absorption rate of the (S) is 5 to 300 seconds, and is used as a cold preservation agent for perishables.
Cooling material described.