JPS6019933B2 - water-containing material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water-containing material used as a cold insulation sealant or the like.

For example, a water-containing material in which water is dispersed in a rubber material is
As seen in 2-4 Iso No. 95, it is a water-containing gel in which water is dispersed in the presence of a surfactant in a continuous layer made by heating and melting a thermoplastic elastomer in an oil component such as machine oil, cylinder oil, transformer oil, etc. is proposed.

Since this type of hydrogel disperses water in oil using a surfactant, it is very difficult to appropriately control the particle size of the dispersed water. Therefore, if you try to disperse water evenly in the elastomer, the water will become too fine and the fine water particles will easily pass through each other, and the resulting water-containing body will have an independent water layer in the elastomer layer. It is difficult to form a dispersed structure, but rather forms a water layer that flows in a capillary manner. This changes the properties of the water-containing material over time, significantly contributing to quality maintenance. That is, since the water layer is continuous from the inside of the water-containing body to the surface, the water contained inside the body gradually dissipates into the outside air, causing separation of the elastomer layer and the water layer. On the other hand, since the capillary water layer is fragmented into small pieces in the elastomer layer, the strength of the entire water-containing body is weak, and it is difficult to maintain the shape, resulting in deformation over time.

Furthermore, when used as a cold insulator, the water-containing body is cooled to below the freezing point to freeze the water contained therein. At this time, if the water layer is independently dispersed in the elastomer, the water-containing body itself maintains its flexibility even when frozen, but in the case of the water-containing body of the prior art where the water layer is like a lotus, the water that connects when frozen. Layers form and the whole becomes unified and loses its flexibility. In addition, when key oil such as machine oil or cylinder oil is used as a melt softener for elastomers, the low molecular weight hydrocarbons contained in the mineral oil are gradually released from the water-containing body, causing a foul odor and It increases the stickiness of the surface and makes it easier to get dirty.

It is particularly unsuitable for use in refrigerators and the like that come into contact with food. The object of the present invention is to improve the drawbacks of the above-mentioned conventional techniques and provide a water-containing body that is hygienic because its moisture content does not change over a long period of time, has stable strength, and can maintain flexibility even below the freezing point.

The above object can be achieved by using a water-absorbing polymer powder and using alkylbenzene as a melt softener for the elastomer when water is dispersed in the elastomer layer.

The present invention will be explained in detail below.

The thermoplastic elastomer used in the present invention is S-B
-S-type vulcanized elastic teleblock polymer, where the S block is a thermoplastic polymer of vinyl compounds such as styrene and Q-methylstyrene, and the B block is an elastic polymer of conjugated gene compounds such as ptadiene and isoprene. be.

The above-mentioned thermoplastic rubber includes the above-mentioned block polymer and ordinary thermoplastic polymers such as ethylene and vinyl acetate copolymer (
EVA), polystyrene, polyethylene, polypropylene, etc., and fillers, pigments, dyes, anti-aging agents, thickeners, ultraviolet absorbers, cross-linking agents, vulcanizing agents, etc. that are usually added to thermoplastic polymers may be added. .

The water-absorbing polymer powder used in the present invention includes, for example, carpoxymethylcellulose, polyethylene oxide, sodium polyacrylate, crosslinked sodium polyacrylate, polyvinyl alcohol, polyvinyl alcohol,
It is a dried powder of water-repellent or water-swellable polymers such as sodium alginate and starch, and the water-absorbing polymer powder absorbs water and expands several to hundreds of times, forming a gel state. It can hold water.

As the melt softener for the thermoplastic elastomer used in the present invention, mono- and dialkylbenzenes having an alkyl group having 10 or more carbon atoms in the side chain are preferably used, and the alkylbenzenes include, for example, didecanylbenzene, dodecylbenzene, stearyl Benzene etc.

An easily evaporated melting aid such as 1-1-1 trichloroethane, carbon tetrachloride, isopropyl ether, acetone, etc. may be added to the softener.

The following steps are used to produce the water-containing material of the present invention.

In step 1, the thermoplastic elastomer, a water-absorbing polymer, and a melting softener are first mixed and heated to 100 to 140°C to melt and uniformly mix the thermoplastic elastomer.

At this time, the amount of the melt softener is 3 to 400 parts by weight (hereinafter simply referred to as parts) of the thermoplastic elastomer 10.
part is added. The amount to be added is appropriately selected depending on the purpose of use and the melting equipment used, but when adding water in a dispersed manner while maintaining the thermoplastic elastomer in a fluid state at a temperature of 100°C or less, it is usually 100 to 20%. The addition amount of Miyako is selected. If the amount added is less than the above,
Good dispersion of water cannot be obtained, and if there is too much water, the gel cannot maintain a stable shape during cooling. As equipment for dissolving, if the proportion of melted softener is high, a tank-type dissolving tank with a boundary blade is used, if the proportion of softener is relatively small, a Nina leg mixer, or even a screw kneader, etc. are used. can. In the melt thus obtained, the water-absorbing polymer is not in a dissolved state but remains in a dispersed state in the form of particles.

The amount of water-absorbing polymer powder to be added varies depending on the type of polymer and the intended use of the water-containing polymer, but for the purpose of cold insulation, it is 0.00 parts per 100 parts of the melt obtained in step 1.
1 to 10 foundations are used. In this case, the amount added is small for polymers such as sodium polyacrylate, which have a large ability to expand with water, and the amount added is large, such as polyvinyl alcohol, which has a relatively low ability to expand with water. As step 2,
Water is added to the mixed melt in which the water-absorbing polymer powder obtained in step 1 is dispersed.

At this time, the temperature of the mixed melt is preferably maintained in the range of 80 to 110 degrees. Water-containing materials that have good shape retention at room temperature rapidly increase in melt viscosity at temperatures below 80° C., making them unsuitable for dispersing water. In addition, when adding water under normal pressure, the added water has an apparent value of 5 to 10% in the above molten mixture.
When the boiling point of q0 increases and the temperature exceeds 110°C, water immediately boils and evaporates, making it impossible to maintain the water dispersed in the molten mixture. Freezing point depressants, surfactants, preservatives, pigments, etc. may be added to the water added. The amount of water to be added is appropriately selected depending on the intended use of the water-containing body, but it is usually mixed in an amount of 5 to 200 parts per 10 parts of the mixed melt.

In particular, when it is desired to obtain a water-containing material that is flexible at temperatures below the freezing point, the amount of water added is preferably 30 to 10%. The water dispersed in the molten mixture is in the form of a very unstable dispersion due to its low compatibility with the molten mixture, but when it comes into contact with the previously dispersed water-absorbing polymer, it quickly becomes highly absorbent. absorbed into molecules.

In this way, the water-absorbing polymer powder gradually absorbs the granulated water particles and becomes large water-absorbing gel particles. As a result, almost no water-only pongee grains remain in the elastomer layer, and large gel particles containing water are formed as an independent dispersed layer in the elastomer layer. In step 3, the melt in which the water-containing gel particles obtained in step 2 are dispersed is cooled and solidified.

At this time, the mixed melt is usually poured into a predetermined mold and cooled and solidified, or is cooled and solidified in large chunks and then cut.
The thus obtained water-containing material exhibits a gel-like body in which the water layer is independently dispersed in the elastomer layer, and since the water layer is not connected, there is no diffusion of water from the water-containing material, and the thermoplastic elastomer layer is completely Since it is a continuous layer, it has sufficient strength to maintain its shape and becomes a gel-like water-containing material with stable quality. Furthermore, the alkylbenzene used as a softening agent is a colorless and odorless liquid hydrocarbon with a boiling point of 300 °C or more, and has extremely low solubility in the thermoplastic elastomer at room temperature, but has a so-called plasticizer effect with solubility at high temperatures. Therefore, when the water-containing material of the present invention is used at room temperature or below, it has an extremely low transpiration property and has the effect of providing stable quality without odor. [Example 1] A compound having the following composition is prepared using a thermoplastic elastomer which is a block copolymer containing 3% by weight of styrene and 7% by weight of butadiene.

Thermoplastic elastomer 10 parts by weight naphthenic oil 3 parts by weight polystyrene
2 parts by weight calcium carbonate
3 parts by weight phenolic anti-aging agent
A heatable metal melting tank equipped with a 1 part weight tank machine,
Add 100 parts by weight of the thermoplastic elastomer compound, 20 parts by weight of alkylbenzene (Vansolve H manufactured by Ryoyu Ka Co., Ltd.), and 0.5 parts by weight of crosslinked sodium polyacrylate powder (Aqua Keep manufactured by Seitetsu Kagaku Co., Ltd.), 135qo
Melting the thermoplastic elastomer while heating it,
Make a viscous molten material.

Vansolve day is 35% by weight and Alkyl containing 65% by weight It is a benzene mixture.

This melt was cooled to 100 DEG C., and water heated to 90-100 degrees Celsius was added to 25 liters of water. Once the well-sealed water is well dispersed, add this mixture to 20x200x
15 Pour into a mold and cool the outside of the mold with water. The above mixture, which was cooled to room temperature and taken out from the mold, was
It was a gel-like body uniformly containing elastic, independently dispersed water particles.

This gel-like material was cooled overnight at -1=0 and taken out, still retaining its flexibility.

Thereafter, the temperature was raised to room temperature, and the same cooling and temperature raising steps were repeated five times, but there was no change in formation or separation of water. [Comparative Example 1] In the same melting tank as in Example 1, 10 parts of thermoplastic elastomer compound and 20 parts of light oil were put.
It was dissolved under the same conditions.

After adding and dissolving 1 part of a surfactant (sorbitan monolaurate), 25 parts of warm water at 90°C was added under pressure while maintaining the temperature above 90°C, and this uniformly dispersed melt was added. The mixture was poured into the same mold as in Example 1, cooled and solidified to obtain an elastic gel state. The gel-like material obtained was softer than that obtained in Example 1, and its thickness decreased by about 20% after being left for a day and night.
After being cooled day and night, the product was almost rigid and had no flexibility.

When this material was repeatedly cooled and heated 5 times in the same manner as in Example 1, about 4 tons of water was separated from the elastic gel-like material. This product also continued to emit the characteristic odor of diesel oil. [Example 2] Thermoplastic elastomer 10, which is a block copolymer of 3% by weight of styrene and 7% by weight of ethylene butylene,
300 parts of alkylbenzene (Bansolve H) and 15 parts of carboxymethyl cellulose (Daiichi Kogaku Seiyaku Celogen BSH) powder were placed in the same dissolution tank as in Example 1, and
Dissolved at 0 qo, surfactant (Nippon Yusashi LP-2 sail) 1
of the mixture was added and dissolved uniformly.

This molten mixture was cooled at 105°C and 30 q0 of hot water was added.
$ portion was added at once and mixed until the water was evenly dispersed. This molten mixture was poured into the same mold as in Example 1, cooled to room temperature, and removed from the mold, yielding an elastic and flexible gel-like body. This gel-like material was cooled at -14 oo overnight and taken out, and still retained its flexibility.

Claims (1)

[Claims] 1. A water-containing material characterized by dispersing water in a mixture of a thermoplastic elastomer, a melt softener mainly composed of mono- and dialkylbenzene, and a water-absorbing polymer.