JP4511500B2 - Hydrogen ion type strongly acidic cation exchange resin - Google Patents

Description

  The present invention relates to a strongly acidic cation exchange resin substantially free of impurity cation forms other than hydrogen ion form and a method for producing the same. By using the strongly acidic cation exchange resin according to the present invention, ultrapure materials that do not contain impurity cations other than hydrogen ions, which are particularly required for semiconductor manufacturing, nuclear power generation and condensate desalination treatment of thermal power plants, etc. You can get water.

  Conventionally, various methods have been industrialized to produce ultrapure water from which various impurity cations and anions are removed from raw water such as city water, groundwater, and industrial water. The latest ultrapure water manufacturing system for semiconductor manufacturing is the most advanced technology. This basically comprises a pretreatment system, a primary pure water production system, and a secondary pure water production system. The pretreatment system includes aggregation, filtration, activated carbon adsorption, and the like. The primary pure water production system is composed of one or two reverse osmosis membrane separation devices and mixed-bed ion exchange devices, or ion exchange pure water devices and reverse osmosis membrane separation devices, and also a secondary pure water production system Consists of an ultraviolet oxidative decomposition apparatus, a mixed bed ion exchange apparatus and an ultrafiltration membrane separation apparatus. The raw water is purified to a level close to theoretical pure water having an electrical specific resistance of 18.24 MΩcm by removing various impurity ions to the limit by these systems.

  The supply water for nuclear power generation is also required to have the same water quality as the above-mentioned ultrapure water. This is because the raw water is fed by a system that uses reverse osmosis membrane separation and ion exchange deionized water equipment similar to the above ultrapure water production system. Manufactured by processing. From the viewpoint of ensuring the safety of nuclear power plant, the condensate needs to maintain high purity water quality. For that purpose, a strongly acidic cation exchange resin (SACER) and a strongly basic anion exchange resin (SBAER) are mixed. The condensate demineralizer as described above is provided to remove impurity ions.

Conventionally, SACER and SBAER used to produce these ultrapure water for industrial use are highly regenerated and purified resins, that is, trace organic impurities and trace ionic impurities contained in the resin. Reduced resin, used in single or mixed bed. The level of regeneration treatment of ion exchange resin for ultrapure water production is determined by each water treatment manufacturer. For example, the regeneration rate of strongly acidic cation exchange resin, that is, the conversion rate of hydrogen ions is 99% or more, A numerical value such as 95% or more is shown for the regeneration rate of the strongly basic anion exchange resin, that is, the hydroxide ion form conversion rate.
When these highly regenerated and refined resins are mixed and used as a mixed-bed ion exchanger, especially in the production of ultrapure water for semiconductor production, a recyclable hydrogen ion type strongly acidic cation exchange resin and A regenerated hydroxyl ion type strongly basic anion exchange resin is mixed and used. Discarded after a certain period of use. Recently, from the standpoint of resource conservation recycling, containers may be replaced and recycled separately to be reused in a primary pure water production system with a low water quality level.

In the above conventional regenerative type SACER, the leakage of impurity cations may occur due to the difference in resin characteristics due to the difference in lots. Among these impurity cations, Na ions are particularly liable to leak due to the low selectivity of strongly acidic cation exchange resins and the problem of Na ⁺ <NH ₄ ⁺ <K ⁺ <Mg ⁺⁺ <Ca ⁺⁺ . Na ions deteriorate the electrical properties of the wafer in semiconductor manufacturing. Although the relationship between the number of Na atoms as impurity atoms and the contamination characteristics on the wafer is not clear, it is said that the electrical characteristics of the wafer deteriorate when the number of Na atoms is several billion / cm ² wafer. It is required to reduce the leakage of impurity cations from the SACER to the limit. The leakage of the impurity cation (M) from the resin is caused by hydrolysis of RM (M-type resin) due to poor regeneration of the strongly acidic cation exchange resin, and M ions leak into the treated water. It is considered. In order to prevent leakage of this impurity cation, each company is working on advanced regeneration treatment as described above. The leakage of the impurity M ions causes a problem of contamination of the wafer and lowers the yield of the wafer.

  Despite the above-mentioned problems, the cation exchange resin was supplied in the Na form. The Na form had a smaller volume and was advantageous in terms of storage stability and handling. This is because even if it is supplied in the hydrogen ion form, it is contaminated with the passage of time and partially changes to the Na form, so that there is a problem in supplying the hydrogen ion form as a practical problem. The strong acid cation exchange resin as in the present invention can theoretically be produced by regenerating Na-type resin, but as shown in the regeneration efficiency curve of FIG. In reality, it is difficult to convert to the hydrogen ion form by regeneration in this way. Moreover, until now, no strongly acidic cation exchange resin in which the impurity cation has been reduced to the level of the resin of the present invention has been found.

  The present invention solves the above-mentioned conventional problems, and provides a novel hydrogen ion type strongly acidic cation exchange resin in which the amount of impurity cations other than hydrogen ions is extremely small and no impurity cation leakage occurs, and a method for producing the same The purpose is to do.

In order to solve the above-mentioned problems, the inventors have intensively studied and succeeded in developing a hydrogen ion type strongly acidic cation exchange resin substantially free of impurity cations, thereby completing the present invention.
That is, the present invention provides a hydrogen ion type strongly acidic cation exchange resin in which impurity cations other than hydrogen ions are 0.1 equivalent% or less of the total exchange equivalent of the ion exchange resin. Preferably, impurity cations other than hydrogen ions in the resin are 0.05 equivalent% or less, and most preferably 0.01% equivalent or less of the total exchange equivalent of the ion exchange resin.

In this specification, impurity cations other than hydrogen ions refer to cations such as sodium, potassium, calcium, magnesium, and ammonium.
Further, in this specification, the total exchange equivalent of the ion exchange resin refers to the total exchange capacity, and indicates the total amount of exchange groups that participate in the ion exchange reaction of the ion exchange resin. It may be considered substantially equivalent to the salt decomposition capacity. These measurements usually follow the exchange capacity measurements made in the industry. Further, the equivalent percentage of the present invention is calculated from the value of the equivalent of the impurity cation form to the total exchange capacity of the resin.

The present invention also provides a method for producing the hydrogen ion type strongly acidic cation exchange resin. That is, the hydrogen ion type strongly acidic cation exchange resin of the present invention comprises 1) a step of producing a crosslinked polymer, 2) a step of sulfonating the crosslinked polymer in the presence of a sulfonation reagent, and 3) 25 ° C. It can be produced by a method comprising a step of hydrating with water having an electrical specific resistance of 5 MΩcm or more, or with dilute sulfuric acid and subsequently with water having an electrical specific resistance of 25 MC or more at 25 ° C.
The crosslinked copolymer used in the present invention can be produced by known raw materials and methods.

  Monomers that constitute the crosslinked copolymer include monovinyl monomers and polyvinyl monomers. Examples of the monovinyl monomer include monovinyl aromatic monomers such as styrene, methylstyrene, chlorostyrene, chloromethylstyrene, ethylstyrene, vinylxylene, vinyltoluene, and vinylnaphthalene. Monomers that can be copolymerized with these monovinyl aromatic monomers include monovinyl aliphatic monomers such as acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, acrylonitrile, and methacrylonitrile. One or more of these can be selected and added in a copolymerizable quantity range to be copolymerized with the monovinyl aromatic monomer.

Next, as the cross-linkable polyvinyl monomer, specifically, polyvinyl aromatic monomers such as divinylbenzene, divinyltoluene, divinylxylene, divinylnaphthalene, trivinylbenzene, trivinylxylene, and di (meta) ) Polyethylene aliphatic monomers such as ethylene glycol acrylate, trimethylolpropane (meth) acrylate, butylene glycol di (meth) acrylate, diallyl maleate, and diallyl adipate.
The amount of the polyvinyl monomer used as the cross-linking agent is the total of all the monomers, that is, the monovinyl aromatic monomer and further the monovinyl aliphatic monomer. It is used in the range of 0.5-60% by weight, preferably in the range of 1.5-50% by weight, based on the amount.
The monovinyl aliphatic monomer is used as desired, but is used in an amount within a range that does not change the performance of the target SACER and the like, and is within a range of 0.1-20% by weight.

  In the present invention, the above-mentioned monomer can be polymerized by a known polymerization method such as suspension polymerization, emulsion polymerization, bulk polymerization, solution polymerization method, etc. This is particularly preferred because coalesced beads can be obtained. As an example, when the suspension polymerization method is used, water or the like can be usually used as the dispersion medium, and those used in known polymerization methods such as polyvinyl alcohol and carboxymethyl cellulose can be used as the dispersant. . As the polymerization initiator, known compounds such as peroxides such as benzoyl peroxide or azo compounds such as azobutyronitrile can be used. The polymerization is usually carried out at a temperature in the range of 50 to 100 ° C. for about 2 to 30 hours. As the operation, water and a dispersing agent are charged and the polymerization initiator is dissolved under stirring. The mass is added and carried out at a given temperature under suspension. The cross-linked copolymer used in the present invention is a substantially non-porous cross-linked copolymer referred to as a gel form, and a known porous material that imparts porosity to the cross-linked copolymer obtained during polymerization. A porous crosslinking copolymer obtained by coexisting a forming agent, for example, an organic solvent having a property of swelling a crosslinked copolymer, a non-swellable organic solvent, a linear polymer soluble in a monomer, or a mixture thereof. A polymer.

The cross-linked copolymer thus obtained is sulfonated to produce SACER. This sulfonation is carried out in the presence or absence of an organic solvent having the property of causing the crosslinked copolymer to swell the polymer. The organic solvent having the property of swelling the polymer is inactive in the reaction system, and specific examples thereof include ethylene dichloride, nitrobenzene, xylene, toluene, trichloroethylene, benzene, propylene dichloride, chlorobenzene, carbon tetrachloride. Etc. When using these, the usage-amount is suitably selected within the range of 0.5-10 times weight with respect to a crosslinked copolymer. These uses are said to allow smooth and uniform introduction of sulfonic acid groups into the crosslinked copolymer under relaxed conditions. Naturally sulfonation can be carried out even in the absence of these organic solvents.
Examples of the sulfonating agent include sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, and the like, or a mixture thereof. By these, the sulfonic acid group is introduced into the crosslinked copolymer. Typically, the reaction time for sulfonation is about 0.3 to 20 hours, and the reaction temperature is 40 to 130 ° C.

  The sulfonated product produced through such a sulfonation process is usually hydrated, filtered, washed, neutralized with sodium hydroxide or sodium carbonate, and washed with water to produce a strongly acidic cation exchange resin in Na form. Is done. However, in the present invention, the sulfonated product produced through the sulfonation step is hydrated under specific conditions, so that the Na ion type strongly acidic cation exchange resin is not produced, and other than the hydrogen ion type. A strongly acidic cation exchange resin free from impurity ions is produced. The resin after the sulfonation reaction is washed with water having an electrical specific resistance of 25 ° C. of 5 MΩcm or more, preferably 10 MΩcm, more preferably 15 MΩcm, most preferably 18 MΩcm or more, and substantially free of impurity cations other than hydrogen ions. The hydrogen ion type strongly acidic cation exchange resin of the present invention can be obtained by adding and highly purifying treatment.

By hydrating with water as described above, the unreacted sulfonation reagent remaining in the resin can be replaced with water without bringing a cation such as Na ion from the outside. Conventionally, a resin was produced by hydrating with industrial water containing a large amount of Na ions and the like, and then neutralizing with sodium hydroxide, sodium carbonate or the like. Therefore, not only the regeneration treatment as described above is necessary, but also by such regeneration treatment, it has been extremely difficult to reduce the concentration of cations other than hydrogen ions to a low level as in the resin of the present invention.
Further, diluted sulfuric acid can be brought into contact with the sulfonated product after sulfonation, and subsequently hydrated with water that does not substantially contain impurity cations other than hydrogen ions. According to this method, it is possible to hydrate in a shorter time than the above-mentioned direct hydration with water after sulfonation. This is thought to be because rapid changes are alleviated and rapid swelling and shrinkage are avoided.

As the raw materials used in the production of the hydrogen ion type strongly acidic cation exchange resin of the present invention, those usually used can be used. However, it goes without saying that a smaller amount of impurity cations is preferable. The smaller the number of impurity cations other than hydrogen ions present in the cross-linked copolymer, the better. For example, it is preferable that the amount of impurity cations contained in the monomer raw material, surfactant, etc. is small.
The strongly acidic cation exchange resin of the present invention is used as a single bed or a mixed bed of this and a regenerated strong basic anion exchange resin to provide ultra-pure water.
Here, the regenerative strong basic anion exchange resin is a hydroxide ion type strongly basic ion exchange resin.
In the production of ultrapure water, the respective ratios of SACER and SBAER when used in a mixed bed can be used in a volume ratio of 10: 1-1: 10, preferably 1: 2-5: 1, more preferably 1: 2-2: 1.
In a mixed bed for condensate demineralization treatment of a nuclear power plant, a thermal power plant or a boiler, the ratio of each of the anion exchange resin and the cation exchange resin is 10: 1-1: 10 in volume ratio. Can be used in the range of 2: 1-1: 2.

Normally, SACER is in the Na form as a commercially available ionic form, which is completely different from the case where it is converted into a hydrogen ion form resin by passing high-purity hydrochloric acid or sulfuric acid. In the present invention, impurity positive ions other than hydrogen are used. It became possible to drastically reduce the amount of ions to 0.1 equivalent% or less, preferably 0.05 equivalent% or less, and most preferably 0.01 equivalent% or less of the total exchange equivalent of the ion exchange resin.
The new hydrogen ion type SACER obtained in this way is a single bed or a mixed bed of the new hydrogen ion type SACER and the regenerative hydroxide ion type SBAER. The system can be used before or after the existing cartridge polisher, or in place of these.

The impurity cation in conventional ultrapure water is usually several tens of ppt level. However, by using the hydrogen ion type SACER of the present invention, ultrapure water in which the impurity cation is reduced to a level of 10 ppt or less, preferably 1 ppt is obtained. Obtainable. The ultra-pure water obtained by the present invention is suitably used as wafer cleaning water used in the production of next-generation 64 megabit or higher memories.
At a nuclear power plant, the desalting capacity is equivalent to or higher than that of conventional resins by using it in the reactor cooling water make-up water production equipment or condensate desalination equipment, and there is absolutely no leakage of impurity cations from the resin. Therefore, ultra-pure water that does not substantially contain impurity cations in the treated water can be produced.
Hereinafter, the present invention will be described in more detail based on examples. However, the examples do not limit the scope of the present invention.

Example 1
According to a known method, 406.8 g of styrene and 93.2 g of 59% pure divinylbenzene were polymerized in an aqueous medium containing a dispersing agent in the presence of a polymerization initiator to produce 515 g of a spherical copolymer. Next, ethylene dichloride was added to the spherical copolymer to sufficiently swell the spherical copolymer, and commercially available 98% concentrated sulfuric acid (Nikko Zinc Co., Ltd. product) was added to the swollen copolymer at 120 ° C. Sulfonation was performed for 5 hours. After completion of the reaction, the mother liquor containing the sulfonated product is placed in a 1 liter four-diameter round bottom flask for 4 minutes (containing approximately 400 g as the sulfonated product), and (1) 18 MΩcm ultrapure water is added in-line while slowly stirring. The sulfonated product was hydrated until the pH of the liquid became almost neutral. (2) Inline, 15.5 MΩcm of deionized water was added with slow stirring, and the sulfonated product was hydrated until the pH of the solution became almost neutral. (3) Inline, 10.3 MΩcm of deionized water was added with slow stirring, and the sulfonated product was hydrated until the pH of the solution became almost neutral. (4) Neutralize first with deionized water of (2), and after the sulfuric acid concentration of the liquid reaches about 25%, it contains 9.6 ppm as Na ions, 1.5 ppm as Mg ions, and 12.2 ppm as Ca ions Using the tap water, the sulfonated product was hydrated three times with slow stirring until the pH of the solution became almost neutral.

なお（１）を例として計算方法を以下に示す。
通薬した１Ｎ塩酸中のナトリウムの濃度：０．０７ｍｇ／リットル（他の陽イオンは不検出であった。）
３５％塩酸のブランク値（ナトリウム検出限界）：０．０５ｍｇ／リットル
従ってサンプル樹脂２０ｇ（２３．９５ｍｌ）より溶離したナトリウム濃度：０．０７ｍｇ／リットル
１リットル樹脂中に含まれるナトリウムの当量：０．０７×１０^−３×１０００／２３．９５÷２３＝１．２７１×１０^−４ｅｑ／リットル−樹脂
不純物陽イオンの当量％＝１．２７１×１０^−４／２．１９×１００＝０．００６ A fixed amount of 20 g of the hydrated hydrogen ion cation exchange resin (1) to (4) above is diluted with ultrapure water containing 35% hydrochloric acid not containing an impurity cation to obtain 1N hydrochloric acid. The drug was passed through and the impurity cations in the filtrate were quantified by flame photometry.
The hydrogen ion-type strongly acidic cation exchange resin separately obtained by a conventional method is obtained by calculation as shown below from the ion exchange capacity in volume conversion (2.19 eq / liter-resin) and the apparent density (835 g / liter-resin). It was.
The results are as follows.

The calculation method is shown below by taking (1) as an example.
Concentration of sodium in 1N hydrochloric acid passed through: 0.07 mg / liter (other cations were not detected)
Blank value of 35% hydrochloric acid (sodium detection limit): 0.05 mg / liter Therefore, the sodium concentration eluted from 20 g (23.95 ml) of sample resin: 0.07 mg / liter The equivalent of sodium contained in 1 liter resin: 0.00 07 × 10 ⁻³ × 1000 / 23.95 ÷ 23 = 1.271 × 10 ⁻⁴ eq / liter—equivalent% of resin impurity cation = 1.271 × 10 ⁻⁴ /2.19×100=0.006

Example 2
Sulfonation was carried out with the concentrated sulfuric acid of Example 1. After completion of the reaction, the mother liquor containing the sulfonated product is added to a 1-liter four-diameter round bottom flask for 4 minutes (containing approximately 400 g as the sulfonated product), and (5) inline, 18 MΩcm ultrapure water is added with slow stirring. The sulfonated product was hydrated until the pH of the liquid became almost neutral. (6) The concentrated sulfuric acid is diluted to about 50% and 25% with ultrapure water (18 MΩcm), first hydrated once with about 50% diluted concentrated sulfuric acid, and then twice with about 25% diluted concentrated sulfuric acid. Thereafter, the sulfonated product was hydrated with ultrapure water until the pH of the solution became neutral. (7) Using sulfuric acid having a sulfuric acid concentration of about 25% obtained by diluting the concentrated sulfuric acid with ultrapure water (18 MΩcm), and removing the 7.5 MΩcm in-line after the sulfuric acid concentration of the mother liquor has reached about 30%. The sulfonated product was hydrated with ionic water until the pH of the solution became almost neutral. (8) Using sulfuric acid having a sulfuric acid concentration of about 20% obtained by diluting the concentrated sulfuric acid with ultrapure water (18 MΩcm), hydrating until the sulfuric acid concentration of the mother liquor is about 25%, then Example 1 Was hydrated with tap water until the pH of the liquid became almost neutral.
The same operation as in Example 1 was performed on 20 g of the hydrated hydrogen ion type cation exchange resin of (5) to (8) above, and the equivalent percentage of the impurity cation in the resin was determined.
The results are as follows.

Example 3
The resins obtained in (1), (2), (4) and (7) of Examples 1 and 2 and the resin after completion of the hydration step obtained by the method of (1) in Example 1 are usually used. Sodium carbonate was added by the method to form a Na-type resin, and this was passed 10 times the amount of 1N hydrochloric acid per liter of the resin, and then the regenerant residue in the resin was washed with ultrapure water. 5% regenerated SACER ((9) resin) was obtained and subjected to the following test.
The following laboratory ultrapure water production system using deionized water as raw water (which can supply ultrapure water with an electric specific resistance of 18 MΩcm at 25 ° C. at 180 liters / hour) was tested. An outline of the system is shown in FIG. Each of the resins (1), (2), (4), (7) and (9) described above and a 1N sodium hydroxide solution are added to the cartridge polisher (5 liters) in the flow shown in FIG. SBAER (Amberlite IRA-402BL, manufactured by Rohm and Haas Company), which was regenerated and purified by 10 times the amount per liter, was mixed at a volume ratio of SACER / SBAER to 2/3 (almost the same equivalent mixture at the exchange capacity ratio). 5 liters of each mixed-bed resin, and the system is operated with SV (Space Velocity) 40 bed volume / hour against the mixed-bed resin, and ultrapure water at the point of use after 1 hour (18 MΩcm or more) ) Quantitative determination of Na ions in ion chromatography (Dionex, USA) ) It was.
The results are as follows.

Example 4
In the flow shown in FIG. 2, the resin of (2) is singly packed into a 5-liter cartridge polisher cylinder to form a single bed, and after the mixed-bed 5-liter cartridge polisher shown in Example 1 using the resin of (9). It was attached in series, the system was operated, and the Na ion concentration in ultrapure water (18 MΩcm) at the point of use after 1 hour was quantified by ion chromatography (manufactured by Dionex, USA). As a result, the Na ion concentration was 2 ppt.

Example 5
The primary terminal mixed-bed ion exchange resin tower shown in FIG. 2 has a regenerated SACER (Amberlite IR-124, manufactured by Rohm and Haas Company) (hydrogen ion form conversion 91.0% by regeneration) and a regenerated SBAER ( Amberlite IRA-402BL, which is a mixed bed (SACER / SBAER mixing ratio of 1/2, 70 liters) of hydroxyl ion form conversion rate by regeneration (80.0%). When this mixed bed SACER was passed through the mixed bed replaced with the resin of (2), the leak amount of Na ions decreased from about 100 ppt to about 3 ppt after 3 hours.

FIG. 1 is a graph showing a regeneration efficiency curve of a conventional strong acid cation exchange resin. FIG. 2 is a diagram showing a schematic flow of the laboratory ultrapure water production system used in Example 4.

Claims (2)

  A hydrogen ion type strongly acidic cation exchange resin in which impurity cations other than hydrogen ions are 0.05 equivalent% or less of the total exchange equivalent of the ion exchange resin.   A hydrogen ion type strongly acidic cation exchange resin in which impurity cations other than hydrogen ions are 0.01 equivalent% or less of the total exchange equivalent of the ion exchange resin.

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