JPH0358366B2 - - Google Patents

Description

Detailed Description of the Invention The present invention relates to separation semipermeable membranes such as ultrafiltration membranes and reverse osmosis membranes, modules composed of the semipermeable membranes, and separation, concentration, purification, etc. using these modules as constituent parts. This invention relates to a colored water-soluble polymer substance that is useful as a material for measuring molecular weight characteristics and leakage inspection in processes.

The purpose of the present invention is to provide a separation semipermeable membrane such as an ultrafiltration membrane, a module composed of the semipermeable membrane, and a material for measuring the molecular weight fractionation of processes and for leakage inspection, which is easy to analyze, has high accuracy, and The object of the present invention is to provide a substance that can be identified with the naked eye, allows the leakage part of a translucent membrane or module to be clearly identified, does not remain after performance measurement, is easy to manufacture and purify, and is inexpensive. .

A detailed explanation of the present invention will be given below.

Separation semipermeable membranes such as ultrafiltration membranes and reverse osmosis membranes, as well as various test substances for modules made up of such semipermeable membranes, have conventionally used proteins such as albumin and cytochrome C, and water-soluble polymers such as dextran. Various dyes are used for measuring molecular weight fractionation and for leakage testing of reverse osmosis membranes. There were no inexpensive and suitable materials for leak testing of reverse osmosis membranes, which have a low salt rejection rate. Also, for measuring molecular weight fractionation,
When using proteins, the extent of the spread of protein molecules largely depends on the state of the solution, and it is difficult to obtain a value that meets the actual conditions of use of the membrane. Particularly if the protein used has a molecular mass distribution, systematic data cannot be obtained. Even if proteins are separated and a protein with a sharp molecular weight distribution is used, the state of a stable aqueous solution differs depending on the type of protein, and the membrane measurement conditions also differ, making it difficult to obtain systematically valid data. I can't do it. Further, purified proteins are expensive, easily putrefied, and require a long time to be washed after performance measurement, making them unsuitable as materials for modular testing. In addition, water-soluble polymers that can be obtained in a series of different molecular weights include dextran and polyvinyl alcohol (hereinafter referred to as PVA), but there are various problems in measuring the concentration of these with common measuring instruments. .

For example, polymers do not absorb visible light or ultraviolet rays, so they cannot be measured with a spectrophotometer, and in the case of a liquid chromatograph, they can be measured using a differential refractometer for detection, but they cannot be measured with aqueous polymer solutions. Since the difference in refractive index with water is small, the detection limit concentration is relatively high, 100 to 500 ppm. TOC (total organic carbon meter) is an instrument with a low detection limit concentration, but it is very expensive. However, when measuring membrane fractionation using these substances, it is necessary to reduce the concentration of the stock solution in order to reduce the influence of the gel layer formed on the membrane surface, and the concentration of the permeated water must also be low. It is becoming difficult to improve the measurement accuracy of transmittance (or rejection rate). Furthermore, since a series of dextrans and their derivatives with various molecular weight distributions are all expensive, it is generally possible to measure the fractionation properties of small ultrafiltration membranes, but it is not possible to measure the fractionation properties of general modules that are in practical use. A large amount of reagents are required to carry out the process or to check the process, making it extremely uneconomical. The same applies to the leakage test material described below. relatively cheap
PVA is also available in a range of different molecular weights, but the problems with detection limits by measuring equipment are similar to those for dextran.

Next, various dyes can be considered as materials for leak testing, but dyes as they are have a small molecular weight (ordinary dyes have a molecular weight of about 100 to 1000), and are outside the limits of the grade used in many areas. In the case of a membrane, it permeates through the membrane, making it impossible to determine whether the substance has passed through the membrane normally or leaked from a defective part, making it useless as a material for leak testing.

It is possible to use the above-mentioned PVA or dextran as a material for leak testing, but the problem with the detection limit of the measuring equipment is the same as above, and as a material for leak testing, it is usually possible to confirm the presence or absence of leakage with the naked eye. desirable. Furthermore, if leakage points can be confirmed in advance during the membrane module manufacturing process, repairs can be made, which will also contribute to improving product yield. In addition, these membrane modules are used in processes such as separation, concentration, and purification as a system in which multiple membrane modules are combined, but in the past, it was extremely difficult to find a small number of leaking modules from a large number of modules. It was hot.

The leak testing material of the present invention can also be used as a method for easily detecting a small number of leaking modules from among a large number of modules in these processes with the naked eye. Furthermore, it is possible not only to discover defective modules, but also to investigate the cause of the defect from the coloring state of the defective portion, which is of course useful for improving processes.

All of these problems can be solved using the materials of the invention.

The configuration of the present invention will be explained in detail below.

The present inventors have obtained a colored polymer material by chemically bonding a reactive dye to a colorless water-soluble polymer material, and have found that this material is extremely useful as a material for measuring the molecular weight fractionation of semipermeable membranes and for leak testing. We have discovered that this is an excellent product and have arrived at the present invention.

The water-soluble polymer substances used in the present invention include synthetic or semi-synthetic polymers such as PVA, dextran, carboxymethyl cellulose, hydroxyethyl cellulose, ethyl cellulose, etc., and natural polymers such as starch, chitosan, etc., but especially synthetic polymers. PVA which is suitable for the purpose of the present invention.

The reason is that synthetic polymers can be arbitrarily synthesized with various polymerization degrees (or molecular weights).
Among these, PVA reacts smoothly with reactive dyes, and it is easy to separate and purify the reaction product and unreacted dye.

On the other hand, as a color-forming substance to be bound to a water-soluble polymer to form a color-forming polymer, a reactive dye normally used for dyes such as cellulose is suitable.

Since the reactive dye chemically bonds with the functional group of the water-soluble polymer, the reaction product becomes a chemically stable colored polymer, which can be used in various tests that can be identified with the naked eye if the concentration is above a certain level. It can be used as a medical substance.

This colored polymer is obtained by reacting one molecule of dye with a molecular weight of 1/50 to 1/100 with one molecule of polymer, so there is almost no shift in molecular weight distribution caused by the reaction. However, the solubility and membrane separation characteristics are the same as those of the polymer before reaction.

In addition, when using the reaction product for the purpose of the present invention, it is necessary to perform purification to remove unreacted dye, but repeated reprecipitation with methanol etc. and simultaneous sharpening of the molecular weight distribution are possible. Either of the extrapass methods may be used.

When the coloring polymer of the present invention obtained by the method described above is used as a material for measuring molecular weight fractionation of semipermeable membranes or as a material for leak testing, there are the following advantages.

(a) It is cheap. (b) If the concentration is around 10 ppm, leakage can be confirmed with the naked eye.

(c) Using a spectrophotometer or liquid chromatograph, leakage can be confirmed down to about 1 ppm.

(iv) Selectively colors the defective parts of the film without coloring the normal film without any defects.

(e) A series of products with sharp molecular weight distributions are available.

(f) Leakage inspection and fractionability measurement can be performed simultaneously.

(g) The manufacturing process can be improved by clarifying the cause of module leakage.

(h) It is possible to provide a material for leak testing for semipermeable membranes and a material for measuring molecular weight fractionation, which have characteristics such as being able to find a leaking module from among a large number of modules in a process.

The present invention will be described in detail with reference to Examples above.

Example 1 (1) Reaction and purification of reaction mixture PVA (GH-23 manufactured by Nippon Gosei Kagaku Co., Ltd.) with an average molecular weight w = 149,000 was dissolved in water to a concentration of 5% by weight and heated to 50°C with stirring. Warm up.

Next, 25 parts of a separately prepared 5% by weight aqueous solution of reactive dye (Sumifix Brilliant Red HB, manufactured by Sumitomo Chemical Co., Ltd.) is added at the same temperature to 50 parts of the PVA aqueous solution. After stirring this for 1 hour while maintaining the temperature at 50°C, 25 parts of a separately prepared 10% by weight aqueous sodium carbonate solution was added, the temperature was raised to 60°C while stirring, and stirring was continued at the same temperature for 3 hours.

The aqueous reaction mixture is cooled to room temperature.
Next, this reaction mixture is purified by the following method. After precipitating the aqueous reaction mixture into acetone, the precipitate is washed repeatedly with methanol. Dry when the dye is no longer visible in the methanol.

After drying, dissolve again in warm water at 90°C, and reprecipitate in methanol. When the methanol becomes colored during reprecipitation, it is washed with fresh methanol, and the above dissolution and reprecipitation are repeated until the methanol is no longer colored and dried.

(2) Measurement of permeability performance using an ultrafiltration membrane Using the sample obtained in (1), permeation performance measurement was performed using an ultrafiltration membrane. The ultrafiltration membranes used were Daicel Chemical Co., Ltd. DUY-M (made of modified polyacrylonitrile, molecular weight cutoff: 20000) and
Reaction using DUY-L (made of modified polyacrylonitrile, molecular weight cut off: 40000) at an operating pressure of 3 Kg/cm ² ,
The concentration of purified product aqueous solution is 1000 ppm. A high performance liquid chromatograph LC-3A manufactured by Shimadzu Corporation was used to measure the concentration to calculate the removal rate.

(3) Absorption wavelength measurement Spectrophotometer (Hitachi Self-Recording Spectrophotometer EPS3T)
The wavelength λmax at which the absorption peak in the visible and ultraviolet regions of the reaction/purification sample obtained in (1) was maximized was determined using the following method. For those with two peaks, the wavelength at the apex position of each peak is shown.

The reaction and purification method is based on the 1963 graduation thesis by Yasuhide Yamagishi, Department of Textile and Dye Engineering, Faculty of Engineering, University of Fukui, and the calculation of the average molecular weight w of various PVA [7] ₃₀ = 11.7 × 10 ^-4 w ^0.57 is WH
Stockmayer, J. of Polymer Sci., C-1,
137 (1963) as reference.

Examples 2 to 6 The same procedure as in Example 1 was conducted except that the raw material PVA and reactive dye used in the reaction were used in the combinations shown in Table 1.

Table 1 shows the transmission performance of each combination of PVA and reactive dye in Examples 1 to 6 and the reaction and purification products that were subjected to one reaction and purification using the absorption wavelength ultraviolet membrane in the visible and ultraviolet regions. It is something that

Comparative Examples 1 to 4 The permeation performance of the raw material PVA used in Examples 1 to 4 through an ultrafiltration membrane was determined (by the same method as described in Example 1 (2)). Concentrations used to calculate removal rates were measured by TOC.

Table 2 shows the test results of Comparative Examples 1 to 4. Considering that the removal rates in Tables 1 and 2 are the same for the corresponding PVA, it can be seen that the properties as a polymer for test substances do not change even if a reactive dye is reacted.

Based on these results, by appropriately selecting substances with different removal rates by the ultrafiltration membrane for each reaction/purification product in Table 1, we can create leakage test substances or molecular weight substances that are easy to confirm with the naked eye and have high analysis accuracy. It can be used as a substance for measuring image quality.

Among them, Example 1 which showed a removal rate R>99.9%,
It can be seen that the reaction and purified products of Nos. 5 and 6 are suitable as materials for leakage testing.

Example 7 Next, in order to examine the coloring properties of these three types of reaction/purification products on the ultrafiltration membrane, they were treated under the conditions shown below. As a result, the reaction/purification products of Examples 1 and 5 were Although the entire product was slightly colored, there was no coloration due to the reaction and purification product of Example 6. Therefore, for the production of modified polyacrylonitrile films, the reaction and purification product of Example 6 is most suitable as a material for leakage testing.

Colorability confirmation test conditions Ultrafiltration membrane: DUY-M manufactured by Daicel Chemical Co., Ltd. (molecular weight cut off 20000) Reaction/purification product concentration: 1000ppm Aqueous solution ultrafiltration pressure: 3Kg/cm ² Temperature: Room temperature Operating time: 1 Time Example 8 Next, in order to investigate whether it is possible to identify the leakage location, several pinholes were intentionally made in the ultrafiltration membrane, and the ultrafiltration membrane was operated under the same conditions as in Example 7. As a result of removing and inspecting the ultrafiltration membrane, the reaction and purification products of Examples 1, 5, and 6 showed bright color only in the pinhole portion of the ultrafiltration membrane.

For comparison, the operation was carried out under the same conditions as in Example 7, except that an aqueous solution adjusted to a concentration equivalent to the added amount of the reactive dye used in Examples 1, 5, and 6 was used, and after the end of the operation, the ultrafiltration membrane was not removed. As a result of the tests, all of the reactive dyes colored the entire ultrafiltration membrane surface and permeated to the ultrafiltration liquid side.

Therefore, leakage testing has not been possible using reactive dyes alone. The fact that the test substance of the present invention did not color areas other than the defective parts of the membrane and that the ultrafiltrate was clear and colorless means that the test substance of the present invention is not a mixture of PVA and reactive dye. This is thought to indicate that they are chemically bonded.

Example 9 Next, in order to investigate the detection limits of the reaction and purified products of Examples 1 to 6, the absorption wavelength in the ultraviolet region was determined.
Using a 285 mμ spectrophotometer and liquid chromatograph (Shimadzu Corporation LC-3A high performance liquid chromatograph column: Sholex oHPAK B800P+
B805+B803) Detector: SPD-2A (UV): Shodex
A calibration curve was prepared from the peak areas of the absorbance chart and the refractive index chart using R1, SE-11 (R), and the concentration was determined to be 1 to 10 ppm.

Figure 1 shows the raw material PVA#500, and Figure 2 shows the raw material PVA#500.
PVA#500 and reactive dye Sumifix Brilliant Red H
-B is an example of an absorbance chart and a refractive index chart of a substance in the middle of purification of a purified product and an unreacted dye.

In Figure 1, 1 is the absorbance measured using an ultraviolet detector, 2 is the refractive index measured using a differential refraction detector, and in Figure 2, 1 is the absorbance of unreacted dye measured using an ultraviolet detector. , 2 indicates the absorbance of the substance in the process of being reacted and purified using an ultraviolet detector, and 3 indicates the refractive index of the same substance measured using a differential refraction detector.

In both Figures 1 and 2, the vertical axis is absorbance using an ultraviolet absorption wavelength of 286μ in the case of an ultraviolet detector, and the refractive index in the case of a differential refraction detector, and the horizontal axis is in both figures.
Indicates elution time (minutes).

In this example, the reaction mixture obtained in Example 3 was added to water using an ultrafiltration membrane DUY-M to maintain the aqueous solution concentration at 1000 ppm, and the permeate of the membrane was filtered through constant volume continuous filtration. It was purified until no coloration was observed. The ultra-overtreatment pressure is 3 Kg/cm ² .

When this purified product is examined using a liquid chromatograph, the results are shown in Figure 3. That is, not only unreacted substances were removed, but also those on the low molecular side were removed.
It can be seen that the peak (molecular weight distribution) is sharp compared to that in Figure 4, which is a liquid chromatograph examination of the substance purified by the reprecipitation method (2). That is, if ultrafiltration treatment is used instead of the purification operation of the reactant shown in Example 1 (2), it is convenient because the removal of unreacted substances and the removal of low molecular weight substances of PVA can be carried out at the same time.

As shown in Table 1, the removal rate is higher than in Example 3, which indicates that low molecular weight substances are removed and the molecular weight distribution becomes sharp. The reaction and purified product purified by the membrane in this way is useful as a substance for highly accurate molecular weight fractionation measurement and a substance for leak testing. In addition, in FIGS. 3 and 4, the vertical axis shows the absorbance using an ultraviolet absorption wavelength of 286 mμ, and the horizontal axis shows the elution time (minutes).

In addition, as shown in Table 3, when the reaction is repeated and the amount of reactive dye added is increased, the detection limit concentration increases.
It turns out that the accuracy can be increased to 0.1-1 ppm. Table 3 shows the amount of dye added to the material obtained by repeating the same reaction and purification three times for the reaction and purification of PVA with an average molecular weight of 149,000 and the chlortriazinyl type reactive dye obtained in Example 1. It is something that

The limit concentration that can be determined with the naked eye for this substance that has been reacted and purified four times is 10 ppm or less, indicating that normal leakage tests can be performed without measuring equipment. The amount of dye added was determined by creating a calibration curve from the peak area of the absorbance chart of a spectrophotometer.

[Brief explanation of drawings]

Figure 1 shows the absorbance chart and refractive index chart of the liquid chromatograph of the raw material PVA used in Example 3, and Figure 2 shows the unreacted dye and the once-reacted/purified dye used in the same example during purification. Absorbance chart and refractive index chart of a liquid chromatograph of a substance. FIG. 3 is a liquid chromatograph absorbance chart of a substance purified using an ultrafiltration membrane, and FIG. 4 is a liquid chromatographic absorbance chart of a substance purified by a methanol reprecipitation method.

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Claims (1)

[Claims] 1. A color-forming polymer substance made by reacting a reactive dye with a colorless water-soluble polymer having a functional group that chemically bonds with the reactive dye, which is characterized by a sharp molecular weight distribution. Membrane performance measurement and leakage testing materials used to evaluate permeable membranes.