JPH0549948A - Anion exchange resin for producing ultrapure water and production of ultrapure water using the same - Google Patents

Abstract

PURPOSE:To provide a strong basic anion exchange resin for producing ultrapure water especially effectively removing fine particles in treated water and reducing the load of a succeeding membrane device. CONSTITUTION:The objective strong basic anion exchange resin is based on a crosslinked copolymer of a monovinyl aromatic compound and a polyvinyl aromatic compound and is characterized by that the half width (<13>C-nuclear magnetic resonance absorptiometery) of the absorption spectrum of carbon of the alkyl or alkanol group of the quaternary ammonium group thereof is 7.5ppm or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anion exchange resin for producing ultrapure water and a method for producing ultrapure water using the anion exchange resin. Specifically, by effectively adsorbing and removing fine particles such as microorganisms, soil components, and metal oxides present in the water to be treated, for example, anion exchange for the production of ultrapure water, which is suitable for cleaning wafers in the semiconductor production process. The present invention relates to a resin and a method for producing ultrapure water using the same.

[0002]

2. Description of the Related Art In recent years, ultrapure water has been used in a wide range of fields such as the semiconductor industry and the pharmaceutical industry. Especially in the semiconductor industry, semiconductor devices, which are the main products, are ICs, LSIs, VLs.
The degree of integration, that is, the so-called number of bits, has increased to SI over the years, and therefore ultrapure water of extremely high purity has been required.

As a control index of the purity of ultrapure water used for cleaning wafers in the manufacturing process of semiconductor devices,
Not only the electrical conductivity (or specific resistance) but also other management indexes such as total organic carbon, the number of viable bacteria, the number of fine particles, and the amount of dissolved oxygen. In particular, minimizing the number of fine particles composed of microorganisms, soil components, metal oxides, etc. present in ultrapure water is a major factor in improving the product yield in semiconductor device manufacturing, so the number of fine particles is extremely small. , For example, a few particles to a particle size of 0.1 μm or more
It is desired to manufacture ultrapure water up to about a unit / ml.

Conventionally, in order to produce ultrapure water, tap water, river water, ground water, etc. have been used as the water to be treated, and these are treated with a coagulation filter, two-bed two-column type to two-bed three-column type ion. Primary pure water system consisting of ion exchange devices such as exchange towers and mixed bed type ion exchange towers, membrane devices such as reverse osmosis membranes and microfiltration membranes, and ultraviolet sterilizers, ion exchange towers, ultrafiltration membranes and reverse Treated by an ultrapure water production system consisting of a secondary pure water system composed of a membrane device such as a permeation membrane, ionic impurities in the water to be treated, and microparticles such as microorganisms, soil components, metal oxides, and dissolved A method of removing impurities such as oxygen to the limit is adopted.

In this method, ionic impurities in the water to be treated are mainly removed by an ion exchange tower, and fine particles such as organic substances, microorganisms, soil components, and metal oxides are mainly membrane devices such as reverse osmosis membranes and ultrafiltration membranes. Are removed by. Therefore, regarding treated water flowing out from the ion exchange tower, ionic impurities leaking into the treated water are the focus of attention, and electric conductivity is mainly used as an index for the purity control of the treated water. The fact is that no consideration is given to fine particles that leak out. The ion exchange column is packed with a cation exchange resin and an anion exchange resin, but because of the ion exchange capacity and ease of operation, for example, an anion exchange resin has a strong basic anion with a degree of crosslinking of 6% or more. Ion exchange resin is used.

If fine particles leak into the treated water flowing out from the ion exchange tower, the load on the membrane device following the ion exchange tower will increase, and as a result, the fine particles that will leak into the ultrapure water finally obtained will increase. It will be. Further, in order to prevent the membrane device from being blocked by the leaked fine particles, it is necessary to regularly clean or replace the membrane device, but this causes a problem that the supply of ultrapure water is interrupted. Occurs.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and controls the leakage of fine particles to the treated water flowing out of the ion exchange tower as much as possible, so that the obstacle caused by the leakage of fine particles is prevented. It is an object of the present invention to provide an anion exchange resin suitable for an ultrapure water production process that does not occur.

[0008]

In order to achieve the above object, the present inventor has examined the behavior of impurities in an ultrapure water production system, in particular, the behavior of fine particles in the vicinity of an ion exchange column. For anion exchange resin,
^The present invention has been accomplished by finding that those having a sharp carbon absorption spectrum of an alkyl group or an alkanol group in a quaternary ammonium group by ¹³ C nuclear magnetic resonance absorption measurement have excellent fine particle adsorption ability. That is, the gist of the present invention, the monovinyl aromatic compound and cross-linked copolymer of polyvinyl aromatic compound and a strong base anion exchange resin having quaternary ammonium groups as a matrix, ¹³ in the heavy water suspension Anion exchange resin for producing ultrapure water, characterized in that the half-value width of the absorption spectrum of carbon of the alkyl group or alkanol group of the quaternary ammonium group measured by nuclear magnetic resonance absorption measurement of C is 7.5 ppm or less. It exists in a method for producing ultrapure water in which water is treated using.

The present invention will be described in detail below with respect to the production of ultrapure water. Various systems have been studied as a system for producing ultrapure water, and a flow chart of an example of a typical system for producing ultrapure water is shown in FIG. The production system of FIG. 1 is a primary system pure water system composed of a coagulation filter, a two-bed three-column type ion exchange column, a reverse osmosis membrane device, and a mixed-bed type ion exchange column, and treated water by the primary system pure water system. In order to further purify the product, a secondary pure water system composed of an ultraviolet sterilizer, a mixed bed type ion exchange tower and an ultrafiltration membrane device is provided. The present invention is applied to the ultrapure water production system shown in FIG. 1, but can be applied to any other system.

2 beds 3 in the ultrapure water production system of FIG.
The tower type ion exchange tower is composed of a cation exchange resin packed tower, a decarbonation tower and an anion exchange resin packed tower, and a mixed bed type ion exchange tower has a cation exchange resin and an anion exchange resin mixed state. Is filled with. The feature of the present invention is that it has a specific physical property as an anion exchange resin used in the above ion exchange tower, that is, when a ¹³ C nuclear magnetic resonance absorption measurement is carried out, the alkyl group of the quaternary ammonium group of the resin is used. Alternatively, a strong basic anion exchange resin having a sharp carbon absorption spectrum of an alkanol group is used.

The strongly basic anion exchange resin is produced by using a copolymer of a monovinyl aromatic compound and a polyvinyl aromatic compound as a base, haloalkylating this, and then aminating it. The thing is obtained by chloromethylating the crosslinked copolymer particle obtained by carrying out suspension copolymerization of styrene and divinylbenzene, and further aminated with amines. And by changing the reaction conditions of these manufacturing processes, the exchange capacity,
It is known that various properties such as water content, swelling / shrinkability, and apparent density can be provided.

For example, by changing the mixing ratio of styrene as a monovinyl compound and divinylbenzene as a polyvinyl compound, the water content of the anion exchange resin finally produced can be changed. Further, various characteristics of the finally produced anion exchange resin can be changed depending on the amount of the polymerization initiator, the temperature during the polymerization, or the amount of the catalyst during the chloromethylation reaction, the reaction temperature, the reaction time, and the like. it can.

The anion exchange resin used for the production of ultrapure water has a problem in that the ability to trap fine particles in treated water is a problem.
It has been found that the surface properties of this anion exchange resin can be achieved by a combination of these manufacturing condition factors.
As the polyvinyl aromatic compound that can be used for producing the resin of the present invention, a compound in which an aromatic ring is substituted with two or more vinyl groups is used, and the aromatic ring may be substituted with an alkyl group having 1 to 3 carbon atoms. Good. For example, aromatic polyvinyl compounds such as divinylbenzene and divinyltoluene are used. Divinylbenzene is particularly preferable. As the monovinyl aromatic compound, styrene, vinyltoluene, vinylnaphthalene, ethylvinylbenzene and the like are used, and styrene is particularly preferable.

One of the conditions that affect the fine particle capturing performance is the ratio of the monovinyl aromatic compound and the polyvinyl aromatic compound. By decreasing the ratio of the polyvinyl compound to the total mixed monomer, the surface of the anion exchange resin is reduced. It is possible to improve the ability of capturing the fine particles. For example, in the case of styrene and divinylbenzene, the mixing ratio thereof is preferably such that the charging ratio of divinylbenzene in all monomers of styrene-divinylbenzene is 6% by weight or less.

The polymerization reaction is usually carried out in the presence of a polymerization initiator, and as the polymerization initiator, dibenzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, azoisobutyronitrile or the like is used. The amount of the polymerization initiator is preferably in the range of 0.05% to 2% based on the total weight of the monomers at the time of polymerization. The temperature at the time of polymerization is optimized depending on the kind of the initiator, the degree of crosslinking, etc., but is generally in the range of 50 to 100 ° C. By increasing the temperature during the polymerization reaction more rapidly, the fine particle trapping capacity tends to decrease.Therefore, the method of maintaining the temperature of the polymerization at a constant temperature for a fixed time or increasing the temperature sequentially depends on the purpose. Used. Generally, in the polymerization at high temperature, the polymerization rate of the copolymer is increased and the fine particle removing ability tends to be lowered.

The crosslinked copolymer thus obtained is reacted with a haloalkylating agent in the presence of a catalyst for haloalkylation. As a catalyst for the reaction of haloalkylation, for example, chloromethylation, aluminum chloride, ferric chloride, boron oxyfluoride, zinc chloride, ethane tetrachloride, stannic chloride,
Aluminum bromide or the like is used. The catalyst amount is generally 0.02 to 2.0 times by weight the total weight of the styrene-divinylbenzene copolymer used in the chloromethyl reaction.

By reducing the amount of the catalyst during the chloromethylation reaction, the fine particle capturing ability can be improved. Therefore, the smaller the amount of catalyst, the higher the fine particle capturing ability of the obtained anion exchange resin. The reaction temperature and reaction time are
Each is used in the range of 30 ° C. to 60 ° C. for 2 hours to 20 hours, but the higher the temperature, the more the minimum reaction conditions that do not hinder the progress of the reaction.
Further, the longer the time, the lower the particle capturing ability tends to be.

Upon amination of the chloromethylated styrene-divinylbenzene copolymer, an alkylamine having 1 to 4 carbon atoms or an alkanolamine is used. Specifically, tertiary amines such as trimethylamine and dimethylethanolamine are used. Is used. The usage ratio is in the range of equimolar to 30 times the molar amount of the chloro group in the chloromethylated styrene-divinylbenzene to be introduced.

The strongly basic anion exchange resin of the present invention is
It is manufactured by combining the optimum conditions of each manufacturing process as described above and has excellent trapping performance of fine particles, but the trapping performance is that the quaternary ammonium salt portion constituting the anion exchange group near the surface of the resin is free. It was expected to be correlated with motility. Then, ¹³ C nuclear magnetic resonance absorption measurement of the anion exchange resin was carried out to find that the resin having a sharp absorption spectrum of the alkyl group or alkanol group of the quaternary ammonium salt, that is, the free mobility of the quaternary ammonium salt portion. It was learned that the resin, which was judged to have a high value, had a better ability to capture fine particles. In the present invention, the respective conditions of the above respective manufacturing steps are adjusted so that the half value width of the absorption spectrum of the alkyl group or the alkanol group of the quaternary ammonium salt is 7.5 ppm or less, preferably 7.0 ppm or less.

The apparatus for measuring nuclear magnetic resonance absorption preferably has a resonance frequency of 270 MHz or higher based on hydrogen nuclides. For example, 270MH
z, 400 MHz, 500 MHz, etc. On the other hand, 27
Below 0 MHz, it is difficult to obtain a clear spectrum because the S / N ratio is low. When the above strongly basic anion exchange resin is used as the anion exchange resin in the ultrapure water production system, the mechanism is not clear, but the fine particles as well as the anionic impurities present in the water to be treated are efficiently adsorbed and removed. can do.

It should be noted that, when this resin is used, no special operation is required. The anion exchange resin is regenerated with an alkaline aqueous solution by a conventional method for regenerating anion exchange resin, and the ion exchange column is filled with the treated water. You can use it for liquid. On the other hand, examples of the strongly acidic cation exchange resin include a commercially available strong basic anion exchange resin obtained by sulfonation of the cross-linked copolymer of styrene and divinylbenzene, and particularly, the ion exchange capacity is large and the mechanical strength is large. The excellent one is preferable. Specific examples of the strong acid cation exchange resin include Diaion (registered trademark of Mitsubishi Kasei Co., Ltd.) SK1B and SK11.
0 and SKN.

In order to carry out the method of the present invention, the ion exchange tower in the above ultrapure water production system is filled with the above cation exchange resin and anion exchange resin, respectively, and regenerated by a conventional method, followed by treatment with water. Pass through. As the flow of the water to be treated is continued, the ion exchange capacity of the ion exchange resin and the adsorption capacity of the fine particles gradually decrease, and the fine particle number gradually increases together with the ionic impurities in the treated water flowing out from the ion exchange tower. When the value reaches a predetermined value, the liquid flow is stopped.

At this time, since the fine particles leaking into the treated water flowing out from the ion exchange tower leak before the ionic impurities, the fine particles leaking out in the conventional water quality control by measuring the electric conductivity. I can't figure out the number. Therefore, it is preferable to install a fine particle meter near the outlet of the ion exchange tower, check the number of fine particles in the outflow water, and stop the water flow when the number of fine particles in the outflow water reaches a predetermined value. Examples of the fine particle meter include PLCA-310 (manufactured by Horiba, Ltd.), ZRV (manufactured by Fuji Electric Co., Ltd.), and TK-200.
Commercial products such as (manufactured by Nippon Rensui Co., Ltd.) are used.

After stopping the passage of the water to be treated, the ion-exchange resin having a lowered function is regenerated. For the regeneration, a regeneration treatment of an ion exchange resin in a normal ultrapure water production system is applied. In the case of a cartridge type ion exchange tower, it may be exchanged with a cartridge filled with a regenerated ion exchange resin in advance. The ion exchange tower after the regeneration treatment is thoroughly washed with treated water and then used again for the production of ultrapure water.

[0025]

EXAMPLES Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples unless it exceeds the gist. Production Example 1 Influence of Catalyst Amount during Chloromethylation: 0.1% by weight of industrial divinylbenzene (purity 55%) and 100 parts by weight of styrene so that the weight% would be 4.0%.
5 parts by weight of benzoyl peroxide was dissolved. The polymerized monomer phase was added to 400 parts by weight of demineralized water in which 0.5 part by weight of polyvinyl alcohol was dissolved as a suspending agent with stirring. After stirring for 1 hour and the monomer phase was sufficiently dispersed in the droplets, the system was heated and the reaction was continued at 80 ° C. for 8 hours. The obtained polymer was cooled, washed thoroughly with water to remove the dispersant, and then vacuum dried at 50 ° C. for 5 hours. Thus, a styrene-divinylbenzene polymer having a crosslinking degree of 4% was obtained.

50 parts by weight of the obtained resin was added to 250 parts by weight of chloromethyl methyl ether and allowed to swell in an anhydrous state at room temperature for 1 hour. After sufficient swelling, 20 parts by weight of zinc chloride was added, and the mixture was heated to 50 ° C. and reacted for 10 hours. After the reaction, 500 parts by weight of demineralized water was added dropwise over 5 hours to decompose excess chloromethyl methyl ether. The obtained chloromethylated copolymer was filtered and then washed with water to remove the residual reaction by-product.

The total amount of the chloromethylated copolymer thus obtained was suspended in 200 parts by weight of an aqueous trimethylamine solution adjusted to 2 mol / l, heated to 50 ° C. under stirring and reacted for 8 hours. .. After the reaction, the obtained anion exchange resin was filtered, packed in a column, and thoroughly washed with water. The anion exchange resin thus obtained had the following properties.

Moisture content 56.8% Exchange capacity 4.04 m
eq / g 1.22 meq / ml This resin is sample A
And The anion exchange resin thus obtained is referred to as Sample B by exactly the same procedure as Sample A except that the amount of zinc chloride in chloromethylation is changed from 20 parts by weight to 50 parts by weight. Sample B had the following general physical properties. Moisture content 49.9% Exchange capacity 4.07 meq
/ G 1.43 meq / ml

Production Example 2 Effect of heating conditions during polymerization The degree of crosslinking of Sample A of Production Example 1 was changed from 4.0% to 3.7%.
And the heating conditions at the time of polymerization are maintained at 80 ° C. for 8 hours, while at 70 ° C. for 13 hours and then 10
Sample C was obtained in the same manner as in Sample A of Production Example 1 except that the temperature was raised to 0 ° C. in 2 hours and the temperature was maintained for 2 hours. The general physical properties of sample C were as follows. Moisture 54.4% Exchange capacity 4.23 meq / g 1.
36 meq / ml

The temperature condition at the time of polymerization of sample C was maintained at 70 ° C. for 13 hours, and then the temperature was raised to 100 ° C. in 2 hours.
Except for holding for 30 hours at 70 ° C., then raising to 80 ° C. in 2 hours, holding for 2 hours, and further raising to 100 ° C. in 2 hours and holding for 2 hours. Sample D was obtained in the same manner as Sample C. The general physical properties of Sample D were as follows. Water 58.3% Exchange capacity 4.24 meq / g 1.
28 meq / ml

Production Example 3 The degree of crosslinking of Sample A of Production Example 1 was changed from 4.0% to 2.0%.
Sample E was obtained in the same manner as sample A except that The general physical properties of sample E were as follows. Moisture content 72.8% Exchange capacity 4.63 meq / g
0.83 meq / ml

Example 1 Nuclear Magnetic Resonance Absorption Measurement of Samples Samples A, B, C, D, E and Diaion SA1
Each of 0A is a chloro type, and ¹³ C is obtained by the following method.
-Nuclear magnetic resonance absorption measurements were performed. Model: JEOL GX-27
0 Resonance frequency: ¹³ C 67.8 MHz Measurement mode: Complete decoupling Broadening factor: 30 Hz Wait time: 1 second Sample: Measured in a state of being suspended and swollen in heavy water Probe: 10Φ

The signals obtained were only carbons of the methyl group of the quaternary ammonium salt. The half-value width of each signal was read from the measurement diagram and divided by the resonance frequency (Hz unit) of ¹³ C-NMR to convert the value into ppm. The results are shown in Table 1. Further, the signal portion of the nuclear magnetic resonance absorption measurement diagram of Sample A is shown in FIG.

Table 1 Full width at half maximum of signal of each sample A 5.6 ppm B 8.1 ppm C 6.1 ppm D 5.0 ppm E 2.3 ppm Diaion SA10A 8.7 ppm

Example 2 Evaluation of Fine Particle Removal Function of Sample A column having a diameter of 80 mm and a length of 1500 mm was filled with 7,000 ml of a strongly acidic cation exchange resin Diaion SKN,
Water having the composition shown in the following Table 2 in which sodium sulfite was added to Yokohama city water as treated water to remove residual chlorine was passed through this column at a flow rate of 30 m / hr, and the outflow water was stored in a tank. did.

[0036] Table 2 Analytical values Attribute water electric conductivity of Yokohama tap water (25 ℃) 120μS / cm total cation 57mg-CaCO _3/1 total anionic 75mg-CaCO _3/1 Number of particles (≧ 0.1 [mu] m) 590,000 pieces / ml On the other hand, 6 columns with a diameter of 30 mm and a length of 2000 mm were prepared, and each column was separately filled with samples A, B, C, D, E and DIAION SA10A, and 6 pieces were prepared. After forming the anion-exchange column of 1., each column was regenerated by an ordinary method with a caustic soda aqueous solution.

The treated water treated with the cation exchange resin stored in the tank in the previous period was separately passed through the above six anion exchange towers at a flow rate of 40 m / hr and flowed out from each anion exchange tower. The number of fine particles having a particle size of 0.1 μm or more present in the treated water was measured by a fine particle meter (PLCA- manufactured by Horiba Ltd.).
310), the water flow was stopped until the number of fine particles leaking into the treated water reached 10000 particles / ml, and then the water flow was stopped, and the amount of water up to that point was collected. The results are shown in Table 3. Table 3 shows the relationship between the type of the strongly basic anion exchange resin used and the amount of water collected.

Table 3 Effect of Water Flow Rate by Each Sample A 430 (1 / 1-R) B 150 (1 / 1-R) C 320 (1 / 1-R) D 450 (1 / 1-R) E 520 (1 / 1-R) Diaion SA10A 120

[0039]

INDUSTRIAL APPLICABILITY The present invention relates to an anion exchange resin having a function of removing fine particles in water, which is used as an anion exchange resin packed in an anion exchange column in an ultrapure water system. By using the resin, it is possible to efficiently remove the fine particles together with the ionic impurities in the water to be treated, so that the load on the subsequent membrane device can be reduced and highly pure ultrapure water can be obtained. Also,
Since the frequency of cleaning or replacement of the membrane device can be reduced, it greatly contributes to the industrial production of ultrapure water.

Further, the field of application of the anion exchange resin according to the present invention is various fields of application requiring fine particle removal, for example, nuclear power, electric power, general industrial water production, pure water production for pharmaceuticals, pure water for cosmetics production. It can be widely used for manufacturing, food refining, etc.

[Brief description of drawings]

FIG. 1 is a flowchart of an example of an ultrapure water production system.

FIG. 2 is a nuclear magnetic resonance absorption measurement diagram of Sample A obtained in Production Example 1, where the horizontal axis represents the absorption frequency (Hz).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryuji Nagatani 3 2-3 Marunouchi, Chiyoda-ku, Tokyo Nihon Renshui Co., Ltd.

Claims (2)

[Claims] 1. A cross-linked copolymer of monovinyl aromatic compound and polyvinyl aromatic compound to a strongly basic anion exchange resin having quaternary ammonium groups as a matrix, the ¹³ C in a heavy water suspension 4 by nuclear magnetic resonance absorption measurement
An anion exchange resin for producing ultrapure water, characterized in that the absorption spectrum of carbon of the alkyl group or alkanol group of the primary ammonium group has a half value width of 7.5 ppm or less. 2. A method for producing ultrapure water, which comprises treating water using the anion exchange resin according to claim 1 in an ion exchange device in an ultrapure water production system.