JPH0366342B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for generating bubbles in a gel with good reproducibility when moving from a high pressure side to a low pressure side.
More specifically, the present invention relates to a water-soluble polymer gel-like composition for use in a detector, for example, in which when a diver ascends from a high-pressure state underwater, the ascent speed is controlled by the bubbles generated in the gel carried by a diver. For workers exposed to hyperbaric environments, such as divers and boxmen, safety measures such as returning to normal pressure are taken according to the working pressure and exposure time in accordance with the Ministry of Labor's Hyperbaric Work Regulations. There is. However, the rate of these hyperbaric workers suffering from diving disease and submergence disease (hereinafter collectively referred to as decompression sickness) is still at an extremely high level. For patients suffering from decompression sickness, pressurization treatment using pre-prepared pressure tanks etc. has been adopted, but there is no way to predict the onset of decompression sickness, and hyperbaric workers are often concerned about the risk of physical damage. It is a condition that can only be treated once the pain appears. In extreme cases, people may develop symptoms several hours after leaving the work site, making treatment difficult and
This results in a great deal of pain to the patient. These are becoming important issues in terms of ensuring the safety of high-pressure workers, such as divers and boxmen. One way to predict decompression sickness is to diagnose it using ultrasound. This method has high technical precision because it directly examines the human body, making it an extremely excellent method.
(Journal of the Japanese Society of Hyperbaric Environmental Medicine (Vol.13No.1-2P27)
~) However, this diagnosis requires a high degree of specialized knowledge, and there is a problem in that a diagnostic expert and diagnostic equipment must be placed at the hyperbaric work site.
It remains within the scope of academic technology. The inventors of the present invention conducted extensive research with the goal of reducing the number of decompression sickness patients among hyperbaric workers, and were inspired by the bubble phenomenon that occurs in gel when returning from high pressure to normal pressure, and based this on the pressure history. On the other hand, we have found a gel-like composition with high bubble generation response accuracy, and therefore provide the present invention. That is, the present invention is an aqueous polymer gel composition consisting of a synthetic water-soluble polymer and agarose, which is obtained by dissolving a polymer mixture consisting of a synthetic water-soluble polymer (A) and agarose (B) in water. This is an aqueous polymer gel composition whose gel foaming characteristics can be controlled solely by the pressure history when the aqueous polymer gel is exposed to conditions that vary the pressure from high pressure to low pressure. (A) used in the present invention may be any synthetic polymer that dissolves substantially transparently in water, for example, the general formula

[Formula]: (R=H, CH ₃ ; X= Na, K, NH ₄ ,

Polymers represented by [formula]), copolymers having this general formula as the main component, general formulas

[Formula]: (R=OH,

A polymer represented by the formula [Formula]), a copolymer having this general formula as a main component, polyacrylamide and/or a copolymer thereof, and the like may be used alone or in combination of two or more. The amount of the above-mentioned copolymer of the synthetic water-soluble polymer is not particularly limited, but the amount of the corresponding main component is 30% by weight or more,
More preferably, it is 50% by weight or more. Although it is possible to obtain a gel from an aqueous solution using only (A) used in the present invention, unless the aqueous solution has a high concentration of 5% by weight or more, it will not gel and the aqueous solution will maintain a fluid state. In addition, the resulting gel generally has high elasticity, which is disadvantageous from the viewpoint of bubble generation. On the other hand, (B), which is used in combination with (A), can produce an aqueous gel-like substance by itself from a low concentration range, but because the gel is cloudy and (B) is a natural product, Quality control is difficult, and in order to control the gel foaming properties, only very limited varieties of agarose can be used, which poses an industrial problem. However, the aqueous gel obtained by mixing (A) and (B) above compensates for the drawbacks of both, and provides properties such as relatively low elasticity, excellent transparency, and easy control of foaming properties. At the same time, the degree of freedom in selecting the quality of (B) is greatly increased, and almost any agarose can be used in the present invention. The mixing ratio of (A) and (B) is 5 to 90% by weight of (A) based on the total amount of both.
It is preferable that (B) is 95 to 10% by weight, more preferably (A) is 10 to 70% by weight (B)
ranges from 90 to 30% by weight. The concentration of the aqueous solution when dissolving the mixture of (A) and (B) above is preferably in the range of 0.2 to 10% by weight. If it is less than 0.2% by weight, the prepared gel will be soft and easily deformed, and the generated bubbles will tend to coalesce, causing variations in the number of bubbles, which is undesirable. If it is more than 10% by weight, the elasticity of the gel is too high, bubbles are incompletely generated, and this causes variation in the measurement of the number of bubbles, which is inappropriate for the purpose of the present invention. The water used to dissolve the mixtures (A) and (B) is distilled water,
Ion-exchanged water or city water can be used, but it is generally dissolved in a weakly alkaline buffer solution with a pH of 9 or less, for example. As reagents for buffer solutions, pH7~ listed in the Chemical Handbook (Maruzen Publishing) etc.
There is no need to particularly limit the type of reagent as long as it exhibits a pH range of 9. The amount of the reagent used is preferably 1% by weight or less, more preferably 0.5% by weight or less based on water. It is effective to add appropriate amounts of preservatives, antifungal agents, bactericidal agents, and antioxidants to prevent the gel from rotting, molding, etc. (A) and (B) can be dissolved in water by mixing (A) and (B), but after dissolving (A) and (B) separately, A mixing method is generally employed. The temperature of the dissolved water is preferably in the range of 50 to 100°C,
If it is below 50°C, the dissolution rate will be extremely slow, which is not preferable. Temperatures exceeding 100°C are unfavorable from an engineering point of view because they require operations such as pressurization. When the aqueous sol of the mixture of (A) and (B) obtained under the above conditions is left at room temperature, it changes to a gel state that is difficult to flow. The obtained gel-like composition is filled into a suitable transparent container made of glass or plastic, but it is easier to fill the composition when it is in a sol state, and it also improves the uniformity of the sample. Easy to obtain. When the gel composition of the present invention is pressurized with a gas such as air, the pressure is maintained for a predetermined period of time, and then the pressure is reduced, the gel foams. The foaming state can be controlled with good reproducibility by using pressurization pressure, pressure holding time, and pressure reduction rate as factors. Since relatively uniform bubbles are formed in the foamed state, it is possible to conveniently use either a method of counting the number of bubbles or a method of measuring an increase in gel volume due to bubble formation. As described above, the gel composition of the present invention is
When examining the reproducibility of the number of bubbles generated using pressurization pressure, pressure holding time, and depressurization speed as factors, the variation in the number of bubbles under the same conditions is within ±15%. Now, under the above operating conditions, the pressurizing pressure is 2Kg/ ^cm2 and 3Kg/ ^cm2 .
If you measure the number of bubbles generated under these conditions, the latter is 10 times the former.
Shows twice the number of bubbles. Taking this difference into consideration, it can be seen that the above-mentioned variation in reproducibility of ±15% is an extremely high precision. If such a phenomenon is applied to, for example, an aqueous polymer gel composition filled in a detector for a diver, work safety can be improved. The present invention will be explained in more detail with reference to Examples. Examples 1 to 4 and Comparative Examples 1 to 3 Polyacrylamide (A) having a molecular weight of 120,000 was prepared in water at 60°C to a concentration of 1% by weight. Next, various types of agarose (B) were prepared in water at 80°C to a concentration of 1% by weight. Liquids (A) and (B) were mixed and stirred at 60°C for 5 hours, then transferred to a rectangular glass container with a bottom area of 1 cm ² and left at room temperature. After 15 minutes, the sample completely turned into a gel. Each Example and Comparative Example are summarized in Table-1. In the table, the transparency of the gel is indicated by the light transmittance at which light with a wavelength of 500 mμ is transmitted through a gel thickness of 1 cm. The number of bubbles at 1Kg/ ^cm2 pressure is the value when the pressure is increased to 1Kg/ ^cm2 with air, held for 4 hours, ^and then reduced to normal pressure for 1 minute. After applying pressure to 2Kg/ ^cm2 and holding it for 4 hours,
This is the value when the pressure is reduced at a rate of Kg/cm ² and returned to normal pressure.

【table】

[Table] Examples 5 to 11 and Comparative Examples 4 to 5 Each of the synthetic water-soluble polymers was prepared into an aqueous solution with a concentration of 0.5% and maintained at a temperature of 60°C. Agarose was then prepared into a 0.5% aqueous solution and kept at a temperature of 80°C. Samples were prepared and tested using the same mixing method as in Examples 1 to 4 under the conditions shown in Table 2. The test evaluation method was carried out in the same manner as in Examples 1 to 4.

[Table] *See Table 1 for brand description of (B) Example 12 50 parts of a 0.5% aqueous solution of polyacrylamide (A) with a molecular weight of 200,000 and high gel temperature type agarose (B).
and 50 parts of a 0.5% aqueous solution were prepared and mixed in the same manner as in Examples 1 to 4, and used as samples. The number of bubbles generated in the obtained sample was evaluated by changing the factors of pressurization pressure, pressure holding time, and pressure reduction rate.

[Table] As shown in Table 3, the greater the air pressurization pressure, the longer the pressure holding time, and the faster the pressure reduction rate, the greater the number of bubbles in the sample.

Claims (1)

[Claims] 1. 10 to 70% by weight of a synthetic water-soluble polymer and agarose
90 to 30% by weight as an aqueous solution with a concentration of 0.2 to 10% by weight, a water-soluble polymer gel composition for a decompression sickness detector with high accuracy of bubble generation response to pressure history, and the synthetic water-soluble polymer is generally formula However, (R=H, CH ₃ ; X=Na, K, NH ₄ ,
Polymers represented by [formula]) and/or copolymers containing the same, general formula The gel composition is a polymer represented by (R=OH, [Formula]) and/or a copolymer containing the same, or a polyacrylamide and/or a copolymer containing the same.