JPH048792A - Cold reserving material of formed rubber - Google Patents

Abstract

PURPOSE:To obtain the title cold reserving material, readily producible, having proper flexibility even at low temperature, excellent feeling in use, excellent shape retention and cold reserving properties, by blending liquid rubber containing plural isocyanate groups with a hydrous hydrogel and dispersing. CONSTITUTION:(A) 100 pts.wt. rubber (preferably 1,000-5,000 molecular weight), (semi)liquid at normal temperature, containing two or more isocyanate groups in the molecule (preferably at the ends) is blended with (B) 50-1,000 pts.wt. hydrous hydrogel having preferably 80-95wt.% water content and dispersed to give the objective cold reserving material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a foamed rubber cold insulating material useful as a cold insulating material.

[Prior Art] As a conventional cold insulating material, JP-A-60-79061 discloses one in which water-containing polymer particles are dispersed in a continuous phase consisting of a teleblock copolymer elastomer and an oil component.

In addition, Japanese Patent Publication No. 11738/1983 discloses that W/○ type emulnoyon, in which an aqueous dispersoid is emulsified and dispersed in a dispersion medium solution containing a high-boiling oily substance, natural rubber, and synthetic rubber, is prepared in the presence of a crosslinking agent. The water-containing kel obtained by crosslinking and keling is shown.

However, the manufacturing process for any of the above-mentioned cold insulating materials is complicated and manufacturing costs are high.

The present inventors have proposed a cold insulating material obtained by dispersing surface-coated hydrous kelp in a vinyl chloride resin that has been kelized with a plasticizer (Japanese Unexamined Patent Publication No. 1-121391). This cold insulation material has excellent cold retention and flexibility at low temperatures. However, if this cold insulation material is used in large and thin cold storage devices,
- If stress was concentrated at a point, the gel would evacuate laterally, revealing areas where no gel was present, resulting in a decrease in cold retention. Also, when I used this cooler vertically, the gel sometimes dripped. Furthermore, when this cooler was used in a large cold storage device, the cold storage device became heavy and its handling was unsatisfactory.

[Problems to be Solved by the Invention] An object of the present invention is to provide a lightweight cold insulating material that can be easily produced, has appropriate flexibility even at low temperatures, is comfortable to use, and has excellent shape retention and cold retention. With the goal.

[Means for solving problems.

In order to achieve the above object, it was discovered that an excellent cold insulating material could be produced by dispersing a hydrogel in a liquid rubber having an isocyanate group at the end, and the present invention was completed.

That is, the present invention provides a foamed rubber cold insulating material obtained by mixing and dispersing (1) a liquid rubber having two or more incyanate groups in one molecule, and (II) a water-containing hydrogel.

The above liquid rubber (1) used as the main component of the mudwax component in the present invention is a fluid rubber that is liquid or semi-liquid at room temperature and has two or more isocyanate groups in the molecule (preferably at the terminal end). means rubber. The molecular weight of the liquid rubber is preferably 1000 to 5000, for example.

Such a liquid rubber may be a commercially available product, or, for example, a liquid modified rubber whose end has been modified with a hydroxyl group may be used as 4,4'-phenylmethane soisocyanate (MDI), toluenosonorate (TDI), etc. It can also be obtained by prepolymerization using an isocyanate compound such as, etc., according to a conventional method.

Examples of the liquid modified rubber in which the terminal end is modified with a hydroxyl group include a terminal modified product of a liquid polymer of a conjugated/ene compound such as butanene, isoprene, dimethylbuta-7ene, piperylene, or chlorobrene, or the above-mentioned conjugated diene compound and styrene, Terminal hydroxyl group-modified products of liquid copolymers with vinyl compounds copolymerizable with the above conjugated diene compounds such as methylstyrene, acrylonitrile, methacrylonitrile, ethylene, propylene, butylene or inbutylene, and terminal hydroxyl group-modified products of liquid thiols. Examples include things. Also natural rubber (NR), synthetic polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butanene (lantum) copolymer rubber (SBR)
, styrene-isoprene (lantum) copolymer rubber (S
IR), acrylonitrile-butanene copolymer rubber (NBR), acrylonitrile-isoprene copolymer rubber: +
It also includes terminal hydroxyl group-modified products of liquid rubbers obtained by depolymerizing solid rubbers such as rubber (NIR) or butyl rubber (IIR). Among the above-mentioned modified rubbers, modified rubber of liquid polybutanene is more preferable.

The water-containing hydrogel (II) used in the present invention is obtained by adding an appropriate amount of water to a generally known hydrogel such as a starch-based hydrogel, an acrylic acid-based hydrogel, or an acrylic acid-vinyl alcohol-based hydrogel. It means something that has been hydrated. The water content in a hydrogel is, for example, ~
Weight percent is preferred. If the water content is less than 80% by weight, foaming or non-uniformity will occur, and if it exceeds 95% by weight, the water-containing hydrogel will coagulate resulting in poor dispersion, which is not preferred.

In the present invention, the above water-containing hydrogel (11) may be further surface-coated. In this case, the surface-coated hydrogel surface may be cured before use.

By coating the surface of the water-containing hydrogel, it improves dispersibility in the liquid rubber and prevents agglomeration of NOITROCHEL.

As surface coating agents, protective colloids such as alkinoic acid sorta, seratin, gum arabic, gum tracanth, and polymeric polyhydric alcohols such as polyhinyl 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 methods include 10 of these surface coating agents.
~15% aqueous solution to 1/2 of the water-containing hydrogel~
Add the same amount as it is, or add 10 to 2
Add 0% by weight and perform a curing treatment. The water used in the present invention may or may not contain anti-icing agents such as ethylene glycol and diethylene glycol.

The foamed rubber cold insulation material of the present invention is produced by mixing and dispersing the above liquid rubber (1) and hydrogel (II), or at that time, a plasticizer is added as a viscosity modifier to ensure good mixing and dispersion. is preferable.

Examples of the plasticizer include oily substances that are liquid at room temperature, such as process oil, liquid paraffin, machine oil, printer oil, transformer oil, and rosin oil.

The foamed rubber cold insulation material of the present invention is obtained by a crosslinking reaction of liquid rubber (I), or the crosslinking reaction proceeds by the incyanate group in the liquid rubber ([) and the water in the hydrogel (II). A crosslinking agent is not necessarily required in the present invention. However, in order to further increase the degree of crosslinking, crosslinking rate, etc., it is possible to add, for example, sulfur, peroxide, quinote, or amine, which are used in conventional vulcanization methods. Incidentally, a vulcanizing agent such as a vulcanization accelerator is added to these materials and crosslinking is performed by a conventional method.

Further, in the above mixing and dispersing step, it is preferable to add an emulsifier in order to improve the dispersion of the hydrous neutrochel (II). The emulsifier may be a conventional emulsifier, such as Neuken EA-73 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.).

Further, in the present invention, fillers may be used depending on the purpose. Fillers used include white carbon, talc, titanium oxide, inorganic oxides such as oil-absorbing carunium carbonate, long-chain fatty acid salts, especially carunium stearate, carunium stearate, aluminum stearate, and carunium oleate. These can be used alone or in combination of two or more. It is preferable that the particles of these fillers be as fine as possible.

In the compounding composition of each of the above compounding agents, liquid rubber (1) 10
0 parts by weight, hydrated/S itrogel (II) is 50~
Preferably, the amount is 1000 parts by weight, the plasticizer is 50 to 400 parts by weight, and the emulsifier is 3 to 40 M parts. If the amount of water-containing hydrogel is less than 50 parts by weight, the cold insulation properties of the cold insulation material will not be sufficient.
Moreover, if it exceeds 1000 parts by weight, it is not preferable because it freezes and solidifies or agglomerates at low temperatures. If the amount of plasticizer is less than 50 parts by weight, the cold insulating material will become too hard, and if it exceeds 400 parts by weight, it will sag and lose its shape retention, which is not preferable. Further, if the amount of the emulsifier is less than 3 parts by weight, the water-containing hydrogel (II) cannot be dispersed well, and if it exceeds 3 parts by weight, the curing reaction will be inhibited, resulting in insufficient curing, which is not preferable.

The method for producing the foamed rubber cold insulating material of the present invention is not particularly limited. For example, liquid rubber (1) is diluted with a plasticizer, an emulsifier is added thereto, and the mixture is uniformly mixed, and water-containing hydrogel (II) is added to this mixture. Once added and dispersed, curing begins and production is possible.

The above dispersion may be carried out using a conventional stirrer or the like. The curing temperature can be carried out at room temperature, or preferably by heating within the range of 80° C. or lower, preferably 60° C. or lower in order to increase production efficiency. The curing time is appropriately selected depending on the curing temperature and the like, and is carried out for example from 0.5 to 2 hours.

[Operations and Effects] In the present invention, curing is thought to proceed by the following mechanism. That is, first, the iso/anate group in the liquid rubber molecule reacts with water in the hydrogel to form carbamic acid. This is then reacted with the iso/anate group of this or another if-like rubber molecule to form an acid anhydride bond (-NH-COOCO-
NH-) is formed and the liquid rubber molecules are cross-linked. Note that this acid anhydride bond immediately undergoes decarboxylation and is converted into a urea bond (-NH-C○-NH-). This crosslinked rubber is then further crosslinked by reacting with iso/anate groups of other liquid rubber molecules. It is thought that crosslinking and curing will proceed in the same manner thereafter.

The rubber material of the present invention becomes a foam by incorporating the generated carbon dioxide scum during the curing reaction. In addition, in the present invention, since a water-containing hydrogel is used, the above-mentioned carbon dioxide scum is taken in very effectively. The foamed rubber material of the present invention contains a high degree of cells, and these cells provide high flexibility, lightness, and heat insulation (that is, cold retention). On the other hand, since the above-mentioned crosslinking occurs to a high degree three-dimensionally, the foamed rubber material of the present invention has sufficient hardness and excellent shape retention. Furthermore, since the above-mentioned crosslinking reaction proceeds very rapidly, it can be carried out even by stirring at room temperature. Therefore, the foamed rubber cold insulating material of the present invention can be manufactured easily in a short time and at low cost.

In addition, the foamed rubber cold insulation material of the present invention obtained in this way is
Even if it is soaked in boiling water, it does not lose its flexibility at -20°C if it is cooled, but it also has excellent shape retention, and no change is observed even when it is repeatedly warmed and cooled. Therefore, it is very easy to use and has excellent thermal efficiency.

The cold insulation material based on the present invention is used for cooling pillows, keeping various parts of the body cold, blood cold, frozen desserts cold, foodstuffs cold, and the like.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

(Example 1) Liquid polybutadiene Liquid modified MDI prepolymer (Po
ly bd HTP-5MLD, 00 parts for Idemitsu Petrochemical Co., Ltd. DOP (di-2-ethylhexyl phthalate)
Add 130 parts of emulsifier (Neuken EA-
73. A matrix component was prepared by adding 40 parts of Dai-Kogyo Seiyaku Co., Ltd. and thoroughly stirring and mixing. On the other hand, a super absorbent resin (Sumikagel 5-50゜ manufactured by Sumitomo Chemical Co., Ltd.)
40 parts and 200 parts of water were well mixed to make 240 parts of water-containing hydrogel dispersed in the matrix component, poured into a mold, and heated at 60°C for 1 hour. Obtained.

The cold insulation material obtained above is 100mm x 130mm x 2
When molded to a size of 0 mm and measured its weight, it was 20
It was 0g. In addition, compared to the weight of the same type of cold insulating material produced according to Japanese Patent Publication No. 62-54344, which weighs 230 g, the weight is reduced to about 85%.

(Cold retention time measurement test) The cold insulation material created in Example 1 was 250 gm of 10009.
It was placed in a 200 zrn polyethylene bag and frozen at 20'C for 12 hours or more. After being taken out, it was left at room temperature of 25°C, and the time until the temperature of the cold insulator reached +1000 was measured. For comparison, similar tests were conducted using conventional ethylene glycol antifreeze and general hydrous gel as cold insulating materials. These results are shown in Table-1.

Table-1: Ethylene glycol antifreeze e,: 3.8 hydrated Kel 4.5 As can be seen from Table-1, the foamed rubber cold insulation material of the present invention has better cold retention than conventional cold insulation materials.

Patent applicant: Sumitomo Rubber Industries, Ltd.

Claims (2)

[Claims] 1. A foamed rubber cold insulation material obtained by mixing and dispersing (I) a liquid rubber having two or more isocyanate groups in one molecule and (II) a water-containing hydrogel. 2. The foamed rubber cold insulation material according to claim 1, which is obtained by mixing and dispersing 50 to 1,000 parts by weight of the hydrated hydrogel (II) to 100 parts by weight of the liquid rubber (I).