JP3173049B2 - Anion exchange resin for ultrapure water production and ultrapure water production method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an anion exchange resin for producing ultrapure water and a method for producing ultrapure water using the same. More specifically, anion exchange for ultrapure water production suitable for cleaning semiconductor wafers, for example, by effectively adsorbing and removing microparticles such as microorganisms, soil components, and metal oxides present in the water to be treated. 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. In the semiconductor industry, in particular, semiconductor devices, which are the main products, are IC, LSI and VL.
The degree of integration, that is, the number of bits, in SI has been increasing over time, and therefore ultrapure water of extremely high purity has been required.

As a control index of the purity of ultrapure water used for cleaning a wafer in a semiconductor device manufacturing process,
Not only the electric conductivity (or specific resistance) but also other management indexes such as total organic carbon, viable cell count, fine particle count, dissolved oxygen content, and the like. In particular, minimizing the number of microparticles composed of microorganisms, soil components, metal oxides, and the like present in ultrapure water as much as possible is a major factor in improving the product yield in semiconductor device manufacturing, so the number of microparticles is extremely small. For example, several to several + as particles having a particle size of 0.1 μm or more.
It has been desired to produce ultrapure water up to about pieces / ml.

Conventionally, in order to produce ultrapure water, tap water, river water, groundwater, etc. are used as the water to be treated, and these are treated with a coagulation filter, a two-bed two-column type or a two-bed three-column type A primary pure water system consisting of an ion exchange device such as an exchange tower and a mixed bed type ion exchange tower, and a membrane device such as a reverse osmosis membrane and a microfiltration membrane, and an ultraviolet sterilizer, an ion exchange tower, an ultrafiltration membrane and a reverse Treated by an ultrapure water production system consisting of a secondary pure water system composed of membrane devices such as osmosis membranes, and ionic impurities and microparticles such as microorganisms, soil components and metal oxides in the water to be treated, 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 removed by a membrane device such as a reverse osmosis membrane or an ultrafiltration membrane. To be removed. For the treated water flowing out of the ion-exchange tower, ionic impurities leaking into the treated water are attracting attention, and electric conductivity is mainly used as an index for controlling the purity of the treated water. In fact, no consideration is given to fine particles that leak out. The ion exchange tower is filled with a cation exchange resin and an anion exchange resin. From the viewpoint of the ion exchange capacity and the ease of operation, for example, as an anion exchange resin, a strongly basic anion having a degree of crosslinking of 6% or more is used. An ion exchange resin is employed.

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

[0007]

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

[0008]

Means for Solving the Problems To achieve the above object, the present inventor studied the behavior of impurities in an ultrapure water production system, particularly the behavior of fine particles around an ion exchange column. For anion exchange resin,
^The present inventors have found that those having a sharp absorption spectrum of carbon 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, and achieved the present invention. 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 An anion exchange resin for producing ultrapure water, wherein the half value width of the carbon absorption spectrum 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, and The present invention resides in a method for producing ultrapure water in which water is treated by using water.

Hereinafter, the present invention will be described in detail with respect to the production of ultrapure water. Various methods have been studied as a system for producing ultrapure water. FIG. 1 shows a flowchart of an example of a typical ultrapure water production system. The production system of FIG. 1 includes a primary pure water system composed of a coagulation filter, a two-bed three-column ion exchange tower, a reverse osmosis membrane device, and a mixed-bed ion exchange tower, and treated water by the primary pure water system. And a secondary pure water system comprising an ultraviolet sterilizer, a mixed-bed type ion exchange tower and an ultrafiltration membrane device for further purifying the water. The present invention is applied to the ultrapure water production system shown in FIG. 1, but can be applied to any other system.

Two beds 3 in the ultrapure water production system of FIG.
The tower type ion exchange tower consists of a cation exchange resin packed tower, a decarbonation tower and an anion exchange resin packed tower, and the mixed bed type ion exchange tower has a mixed state of cation exchange resin and anion exchange resin. Filled with. The feature of the present invention is that the specific properties of the anion exchange resin used in the above-mentioned ion exchange tower, namely, when the ¹³ C nuclear magnetic resonance absorption measurement is performed, the alkyl group of the quaternary ammonium group of the resin is used. Alternatively, a strong basic anion exchange resin having a sharp absorption spectrum of carbon of the 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 the copolymer, and then aminating the copolymer. These are obtained by subjecting a crosslinked copolymer particle obtained by suspension copolymerization of styrene and divinylbenzene to chloromethylation and further amination with amines. By changing the reaction conditions of these manufacturing processes, the exchange capacity,
It is known that various properties such as moisture, swelling / shrinking property, and apparent density can be provided.

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

The anion exchange resin used in the production of ultrapure water has a problem particularly in the performance of capturing fine particles in treated water.
It has been found that the surface properties of the anion exchange resin can be achieved by a combination of these manufacturing condition factors.
As the polyvinyl aromatic compound that can be used in the production of the resin of the present invention, a compound in which two or more vinyl groups are substituted on an aromatic ring 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. Particularly, divinylbenzene is preferable. As the monovinyl aromatic compound, styrene, vinyl toluene, vinyl naphthalene, ethyl vinyl benzene and the like are used, and styrene is particularly preferable.

One of the conditions affecting the fine particle trapping performance is the ratio of the monovinyl aromatic compound to the polyvinyl aromatic compound. By reducing the ratio of the polyvinyl compound to the total mixed monomers, the surface of the anion exchange resin can be reduced. Can improve the ability to capture fine particles. For example, in the case of styrene and divinylbenzene, it is preferable that the mixing ratio of the divinylbenzene in all the styrene-divinylbenzene monomers is 6% by weight or less.

The polymerization reaction is usually carried out in the presence of a polymerization initiator, such as dibenzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, azoisobutyronitrile and the like. The amount of the polymerization initiator is preferably in the range of 0.05% to 2% with respect to the total monomer weight at the time of polymerization. The temperature at the time of polymerization is optimized depending on the type of the initiator, the degree of crosslinking, and the like, but is generally in the range of 50 to 100 ° C. As the temperature during the polymerization reaction increases more rapidly, the ability to capture fine particles tends to decrease.Therefore, depending on the purpose, 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. In general, polymerization at a high temperature tends to increase the degree of polymerization of the copolymer and decrease the ability to remove fine particles.

The crosslinked copolymer thus obtained is reacted with a haloalkylating agent in the presence of a catalyst to effect haloalkylation. Catalysts for the reaction of haloalkylation, for example, chloromethylation, include aluminum chloride, ferric chloride, boron oxyfluoride, zinc chloride, ethane tetrachloride, stannic chloride,
Aluminum bromide or the like is used. The amount of the catalyst is generally in the range of 0.02 to 2.0 times 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 ability to capture fine particles can be improved. Therefore, the smaller the amount of the catalyst, the more the ability of the resulting anion exchange resin to capture fine particles. The reaction temperature and reaction time are
Each is used in the range of 30 ° C. to 60 ° C. and in the range of 2 hours to 20 hours. Under the conditions of the minimum reaction condition or more that does not hinder the progress of the reaction, the higher the temperature,
Also, the longer the time, the lower the ability to capture fine particles tends to be.

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

The strongly basic anion exchange resin of the present invention comprises:
It is manufactured by combining the above-mentioned optimum conditions of each manufacturing process, and is excellent in the capturing performance of fine particles, but the capturing performance is free of the quaternary ammonium salt portion constituting the anion exchange group near the surface of the resin. Correlation with motility was expected. When ¹³ C nuclear magnetic resonance absorption measurement was performed on the anion exchange resin, 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 has been found that the resin judged to be higher has a better ability to capture fine particles. In the present invention, the conditions of each of the above production steps are adjusted to adjust the half-value width of the absorption spectrum of the alkyl group or alkanol group of the quaternary ammonium salt to 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 more on the basis of a hydrogen nuclide. For example, 270MH
z, 400 MHz, 500 MHz, and the like. 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-mentioned strong 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 are efficiently adsorbed and removed together with the anionic impurities present in the water to be treated. can do.

When this resin is used, no special operation is required. The resin which has been regenerated with an aqueous alkali solution by an ordinary method for regenerating an anion-exchange resin is filled in an ion exchange tower and the water to be treated is passed through. The solution may be provided. On the other hand, examples of the strongly acidic cation exchange resin include commercially available strong basic anion exchange resins obtained by sulfonating the crosslinked copolymer of styrene and divinylbenzene, and in particular, have a large ion exchange capacity and a high mechanical strength. Are preferred. Specific examples of the strongly acidic cation exchange resin include Diaion (registered trademark of Mitsubishi Kasei Corporation) SK1B and SK11.
0 and SKN.

In order to carry out the method of the present invention, the ion exchange tower in the ultrapure water production system is filled with the cation exchange resin and the anion exchange resin, respectively, and regenerated by a conventional method. 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 number of fine particles gradually increases together with the ionic impurities in the treated water flowing out of the ion exchange tower. When the value reaches a predetermined value, the liquid supply is stopped.

At this time, the fine particles leaking into the treated water flowing out of the ion exchange tower leak prior to the ionic impurities. Therefore, the fine particles leaking in the conventional water quality control by measuring the electric conductivity are used. I can't keep track of 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 effluent, and stop the flow when the number of fine particles in the effluent 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 (Nippon Rensui) are used.

After stopping the passage of the water to be treated, the ion-exchange resin having a reduced 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 replaced with a cartridge filled with regenerated ion exchange resin in advance. The ion-exchange tower after the regeneration treatment is sufficiently washed with treated water, and then supplied to the production of ultrapure water again.

[0025]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. Production Example 1 Influence of amount of catalyst at the time of chloromethylation: 0.1% by weight of industrial divinylbenzene (purity: 55%) and 100 parts by weight of styrene such that the weight% becomes 4.0%.
5 parts by weight of benzoyl peroxide were dissolved. The polymerization 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 while stirring. Stirring was performed for 1 hour, and after the monomer phase was sufficiently dispersed in droplets, the system was heated and the reaction was continued at 80 ° C. for 8 hours. After cooling the obtained polymer, it was sufficiently washed with water to remove the dispersant, and then dried under vacuum at 50 ° C. for 5 hours. Thus, a styrene-divinylbenzene polymer having a degree of crosslinking of 4% was obtained.

50 parts by weight of the obtained resin was added to 250 parts by weight of chloromethyl methyl ether, and the mixture was allowed to swell under anhydrous conditions 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 resulting chloromethylated copolymer was filtered and washed with water to remove remaining reaction by-products.

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. with stirring, and reacted for 8 hours. . After the reaction, the obtained anion exchange resin was filtered, packed in a column, and sufficiently washed with water. Thus, the obtained anion exchange resin had the following properties.

Water 56.8% Exchange capacity 4.04m
eq / g 1.22 meq / ml
And The anion-exchange resin obtained was designated as Sample B by exactly the same procedure as Sample A except that the amount of zinc chloride during chloromethylation was changed from 20 parts by weight to 50 parts by weight. Sample B had the following general physical properties. Moisture 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 from 4.0% to 3.7%.
And heating conditions at the time of polymerization are kept at 80 ° C. for 8 hours, while kept at 70 ° C. for 13 hours,
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 maintained for 2 hours. The general physical properties of Sample C were as follows. Moisture 54.4% Exchange capacity 4.23 meq / g
36 meq / ml

The temperature condition during the 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 at 70 ° C. for 13 hours, then raising the temperature to 80 ° C. for 2 hours, holding for 2 hours, further raising the temperature to 100 ° C. for 2 hours, and holding for 2 hours. In the same manner as in Sample C, Sample D was obtained. The general physical properties of Sample D were as follows. Moisture 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 from 4.0% to 2.0%.
Sample E was obtained in the same manner as in Sample A, except that The general physical properties of Sample E were as follows. Water 72.8% Exchange capacity 4.63 meq / g
0.83 meq / ml

Example 1 Measurement of Nuclear Magnetic Resonance Absorption of Samples Samples A, B, C, D, E and Diaion SA1
0A each as chlor form, ^13C by the following method
-A nuclear magnetic resonance absorption measurement was performed. Model: JEOL GX-27
0 Resonant frequency: ¹³ C 67.8 MHz Measurement mode: Complete decoupling Broadening factor: 30 Hz Waiting time: 1 second Sample: Measured while suspended and swollen in heavy water Probe: 10Φ

The signals obtained were respectively only the carbon of the methyl group of the quaternary ammonium salt. The half-value width of each signal was read from the measurement diagram, and the value converted to ppm was used by dividing by the resonance frequency (in Hz) of ¹³ C-NMR. Table 1 shows the results. FIG. 2 shows a signal portion of the nuclear magnetic resonance absorption measurement diagram of Sample A.

Table 1 Half width 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 Diamond ion SA10A 8.7 ppm

Example 2 Evaluation of the function of removing fine particles from a sample A column having a diameter of 80 mm and a length of 1500 mm was filled with 7000 ml of strongly acidic cation exchange resin Diaion SKN.
Water having the composition shown in Table 2 below, in which sodium sulfite was added to the city water to remove residual chlorine as water to be treated, was passed through the column at a flow rate of 30 m / hr, and the effluent 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 / ml On the other hand, six columns each having a diameter of 30 mm and a length of 2,000 mm were prepared, and each column was separately filled with samples A, B, C, D, E and Diaion SA10A, and each column was filled with six columns. After the formation of the anion exchange towers, each of the towers was regenerated with a sodium hydroxide aqueous solution by a conventional method.

The treated water treated with the cation exchange resin stored in the tank in the previous period was separately passed through the above-mentioned six anion exchange towers at a flow rate of 40 m / hr, and flowed out of 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 using a fine particle meter (PLCA- manufactured by Horiba, Ltd.).
310), the water flow was continued until the number of the fine particles leaking into the treated water reached 10,000 / ml, then the water flow was stopped, and the amount of water up to that time was collected. Table 3 shows the results. Table 3 shows the relationship between the type of the strongly basic anion exchange resin used and the amount of collected water.

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) Diamond ion SA10A 120

[0039]

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

The fields of application of the anion exchange resin according to the present invention include various application fields which require the removal of fine particles, for example, nuclear power, electric power, general industrial water production, pharmaceutical production pure water, cosmetics production pure water. It can be widely used for production, food refining, etc.

[Brief description of the drawings]

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

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

Continuation of the front page (72) Inventor Ryuji Nagatani 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Rensui Co., Ltd. (56) References JP-A-1-176491 (JP, A) JP-A-3-181385 (JP, A) JP-A-4-108588 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01J 39/00-49/02 C02F 1/42

Claims (2)

(57) [Claims] 1. A strongly basic anion exchange resin having a quaternary ammonium group based on a crosslinked copolymer of a monovinyl aromatic compound and a polyvinyl aromatic compound, the resin comprising ¹³ C The above 4 based on nuclear magnetic resonance absorption measurement
An anion exchange resin for producing ultrapure water, wherein the half value width of the absorption spectrum of carbon of an alkyl group or an alkanol group of a quaternary ammonium group is 7.5 ppm or less. 2. A method for producing ultrapure water, comprising treating water with the anion exchange resin according to claim 1 in an ion exchange device in the ultrapure water production system.