JP3248602B2 - Ultrapure water production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing ultrapure water, and more particularly to a method for producing impurities other than hydrogen ions, which is required for semiconductor production, nuclear power generation and condensate desalination of thermal power plants. The present invention relates to a method for producing ultrapure water containing no ions.

[0002]

2. Description of the Related Art Conventionally, various methods have been industrialized to produce ultrapure water from which various cations and anions have been removed from raw water such as city water, groundwater and industrial water. The latest ultrapure water production system for semiconductor production can be said to be the most advanced technology. It basically consists of a pretreatment system, a primary pure water production system, and a secondary pure water production system. The pretreatment system is composed of coagulation, 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 a mixed bed type ion exchange device, or an ion exchange pure water device and a reverse osmosis membrane separation device. Is composed of an ultraviolet oxidative decomposition device, a mixed bed type ion exchange device and an ultrafiltration membrane separation device. Raw water is removed by these systems to the utmost to remove various impurity ions and purified to a level close to theoretical pure water with an electrical resistivity of 18.24 MΩcm.

[0003] The water supply for nuclear power generation is also required to have a water quality equivalent to that of the ultrapure water, which is a system using a reverse osmosis membrane separation production and an ion-exchange pure water apparatus in accordance with the ultrapure water production system. It is manufactured by treating raw water. From the viewpoint of ensuring the safety of a nuclear power plant, it is necessary to maintain high-purity water for condensate recovery. For this purpose, a mixed bed of strongly acidic cation exchange resin (SACER) and strongly basic anion exchange resin (SBAER) is used. A condensate desalination apparatus is provided to remove impurity ions.

Conventionally, SACER and SBAER used for producing these industrial ultrapure waters are highly regenerated and purified resins, that is, trace organic impurities and trace ions contained in the resin. A resin with reduced sexual impurities, which is used in a single bed or a mixed bed. The level of the regeneration treatment of the ion exchange resin for ultrapure water production is determined by each water treatment manufacturer. For example, the regeneration rate of a strongly acidic cation exchange resin, that is, the hydrogen ion form conversion rate is 99% or more. The regeneration rate of the strongly basic anion exchange resin, that is, the conversion rate of the hydroxide ion form is 95%.
Numerical values such as% or more are shown. When these highly regenerated and purified resins are mixed and used as a mixed bed type ion exchange device, especially in the production of ultrapure water for semiconductor production, a regenerated hydrogen ion type strongly acidic cation exchange resin is placed in a cylinder type container. A regenerated hydroxyl ion type strongly basic anion exchange resin is mixed and filled for use. After being used for a certain period, it is discarded. In recent years, from the standpoint of resource conservation recycling, the containers may be replaced and regenerated separately and reused in the primary water purification system with low water quality.

In the above-mentioned conventional regeneration type SACER, leakage of impurity cations may occur due to differences in resin characteristics due to differences in lots and the like. Among these impurity cations, Na ion is particularly likely to leak due to the low selectivity of the strongly acidic cation exchange resin and the problems of Na ⁺ <NH ₄ ⁺ <K ⁺ <Mg ⁺⁺ <Ca ⁺⁺ . Na ions degrade 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 number of Na atoms is several billions / cm ² and the electrical characteristics of the wafer deteriorate. It is required that the leakage of impurity cations from SACER be reduced to the utmost. 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 leaking into the treated water. It is considered. In order to prevent the leakage of the impurity cations, as described above, each company works on advanced regeneration processing. The leakage of the impurity M ions causes a problem of causing contamination of the wafer and lowering the yield of the wafer.

[0006] Despite the above-mentioned problems, the reason why the cation exchange resin is supplied in the form of Na is as follows.
The a-form has a smaller volume and is advantageous in terms of storage stability and handling. Also, even if supplied in the hydrogen ion form, it is contaminated with time and partially changes to the Na-form. The problem was that there was a problem in supplying in the hydrogen ion form. Although the strongly acidic cation exchange resin used in the present invention can be theoretically produced by regenerating a Na-type resin, FIG.
As shown in the regeneration efficiency curve, a very large amount of a regenerant must be used, and in practice, it is difficult to convert to a highly hydrogen ion form by such regeneration.
To date, no strongly acidic cation exchange resin in which impurity cations have been reduced to a level such as the resin used in the present invention has been found.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing ultrapure water substantially free of impurity cations other than hydrogen ions.

[0008]

Means for Solving the Problems The inventors of the present invention have intensively studied to solve the above-mentioned problems, and as a result, by using a hydrogen ion type strongly acidic cation exchange resin substantially free from impurity cations, The present invention has been completed. That is, the present invention provides 1) a step of producing a crosslinked polymer, 2) a step of sulfonating the crosslinked polymer in the presence of a sulfonating reagent, and 3) externally adding impurity cations other than hydrogen ions.
Without resulting from, 5Emuomegashi electrical resistivity of 25 ° C.
m in water or at 25 ° C. following dilute sulfuric acid
A hydrogen ion type strongly acidic cation exchange resin produced by a method including a step of hydrating with water having an electric resistivity of 5 MΩcm or more, wherein impurity cations other than hydrogen ions are:
A single bed of a hydrogen ion type strongly acidic cation exchange resin having 0.1 equivalent% or less of the total exchange equivalent of the ion exchange resin, or the hydrogen ion type strongly acidic cation exchange resin and a regenerative strong basic anion exchange resin And a method for producing ultrapure water including a step of passing water through a mixed bed with water. Impurity cations other than hydrogen ions in the hydrogen ion type strongly acidic cation exchange resin are preferably 0.1 equivalent of the total exchange equivalent of the ion exchange resin.
It is at most 05 equivalent%, more preferably at most 0.01% equivalent.

In the present specification, impurity cations other than hydrogen ions refer to, for example, 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, which indicates the total amount of exchange groups participating in the ion exchange reaction of the ion exchange resin. It can be considered substantially equivalent to the salt decomposition capacity. These measurements usually follow the exchange capacity measurements made in the art. In the resin used in the present invention, the equivalent% is calculated from the value of the equivalent of the impurity cation form to the total exchange capacity of the resin.

[0010] In the above-mentioned method for producing the hydrogen ion type strongly acidic cation exchange resin used in the present invention, the crosslinked polymer can be produced by known raw materials and methods.

The monomers constituting the crosslinked copolymer include:
Monovinyl monomers and polyvinyl monomers are exemplified. Monovinyl monomers include styrene, methylstyrene,
Monovinyl aromatic monomers such as chlorostyrene, chloromethylstyrene, ethylstyrene, vinylxylene, vinyltoluene, and vinylnaphthalene are exemplified. Examples of monomers copolymerizable with these monovinyl aromatic monomers include monovinyl aliphatic monomers such as acrylic acid, methacrylic acid, acrylates, methacrylates, acrylonitrile, and methacrylonitrile. ,
One or more of these can be selected and added within a quantitative range that allows copolymerization, and can be copolymerized with a monovinyl aromatic monomer.

Next, as the crosslinkable polyvinyl monomer, specifically, polyvinyl aromatic monomers such as divinylbenzene, divinyltoluene, divinylxylene, divinylnaphthalene, trivinylbenzene and trivinylxylene; Examples thereof include polyvinyl aliphatic monomers such as ethylene glycol di (meth) 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 amount of the monomers, that is, the total amount of the monovinyl monomer and the polyvinyl monomer when a monovinyl aromatic monomer or a monovinyl aliphatic monomer is contained. 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 that does not change the performance of the target SACER, etc., and is in the range of 0.1 to 20% by weight.

The above-mentioned monomers can be polymerized by known polymerization methods such as suspension polymerization, emulsion polymerization, bulk polymerization, solution polymerization and the like. It is particularly preferable because beads can be obtained. When the suspension polymerization method is used as an example, water or the like can be used as a dispersion medium, and a dispersant such as polyvinyl alcohol or carboxymethyl cellulose that is used in a known polymerization method can be used. . Known polymerization initiators such as peroxides such as benzoyl peroxide and azo compounds such as azobutyronitrile can be used. The polymerization is usually carried out at a temperature in the range of 50-100 ° C. for about 2-30 hours. The operation is as follows: water, a dispersing agent and the like are charged and the polymerization initiator is dissolved therein with stirring. The addition is carried out at a predetermined temperature under suspension. The crosslinked copolymer is a substantially non-porous crosslinked copolymer called a gel form, or a known porous forming agent that imparts porosity to the crosslinked copolymer obtained at the time of polymerization, such as a crosslinked copolymer. Examples include an organic solvent having a property of swelling a polymer, a non-swelling organic solvent, a linear polymer soluble in a monomer, and a porous cross-linked copolymer obtained by coexisting a mixture thereof.

The crosslinked 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 swelling the crosslinked copolymer. The organic solvent having the property of swelling the polymer is inert in the reaction system, and specific examples thereof include ethylene dichloride, nitrobenzene, xylene, toluene,
Trichloroethylene, benzene, propylene dichloride, chlorobenzene, carbon tetrachloride and the like. When these are used, their amounts are appropriately selected within the range of 0.5 to 10 times the weight of the crosslinked copolymer. These uses are said to allow the sulfonic acid groups to be smoothly and uniformly introduced into the crosslinked copolymer under relaxed conditions. Of course, 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, and a mixture thereof, and the like, whereby a sulfonic acid group is introduced into the crosslinked copolymer. Typically, the sulfonation reaction time is about 0.3-20 hours, and the reaction temperature is 40-1.
Performed at 30 ° C.

The sulfonated product produced through such a sulfonation step is usually hydrated, filtered, washed, neutralized with caustic soda or sodium carbonate, washed with water, and subjected to strong acid cation exchange of Na form. A resin is manufactured. On the other hand, when the resin used in the present invention is produced, the sulfonated product produced through the sulfonation step is subjected to a hydration treatment under a specific condition, thereby obtaining a strongly acidic cation exchange in the form of Na ion. Without producing a resin, a strongly acidic cation exchange resin containing no impurity ions other than the hydrogen ion form is produced. The resin after the sulfonation reaction is washed with water having an electrical resistivity at 25 ° C. of 5 MΩcm or more, preferably 10 MΩcm, more preferably 15 MΩcm, and most preferably 18 MΩcm, substantially free from impurity cations other than hydrogen ions. The hydrogen ion form strong acidic cation exchange resin used in the present invention can be obtained by the combination and highly purified treatment.

By hydrating with water as described above, N
The unreacted sulfonating reagent remaining in the resin can be replaced with water without introducing a cation such as a ion from the outside. Conventionally, a resin has been produced by hydration with industrial water containing a large amount of Na ions and the like, followed by neutralization with caustic soda, sodium carbonate and the like. Therefore, not only the above-mentioned regeneration treatment is necessary, but also it is extremely difficult to reduce the concentration of cations other than hydrogen ions to such a low level as the resin used in the present invention. there were.

After sulfonation, the sulfonated product may be brought into contact with diluted sulfuric acid, followed by hydration with the above-mentioned water substantially free of impurity cations other than hydrogen ions. According to this method, hydration can be performed in a shorter time than after hydration directly with water after sulfonation. It is considered that this is because a sudden change is alleviated and a sudden swelling / shrinking is avoided. As the raw materials used in the production of the hydrogen ion type strongly acidic cation exchange resin used in the present invention, those usually used can be used. However, it is needless to say that the amount of the impurity cation is preferably small. It is preferable that the amount of impurity cations other than hydrogen ions present in the crosslinked copolymer be as small as possible. The regenerative strong basic anion exchange resin is a hydroxyl ion type strong 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 range of 10: 1-1: 10, preferably 1: 2. -5: 1, more preferably 1: 2
-2: 1. Further, in a mixed bed for condensate desalination treatment of a nuclear power plant, a thermal power plant or a boiler, the respective proportions of the anion exchange resin and the cation exchange resin are 10: 1-1: 10 by volume. And it is preferably 2: 1-1: 2. Normally, SACER is a commercially available ionic form of Na form, which is completely different from the case where high purity hydrochloric acid or sulfuric acid is passed through to convert it into a hydrogen ion form resin. 0.1 equivalent% or less, preferably 0.05 equivalent% or less, and most preferably 0.01 equivalent% of the total exchange equivalent of the ion exchange resin.
It became possible to drastically reduce it below. The new hydrogen ion form SACER thus obtained is composed of a single bed or a new hydrogen ion form SACER and a regenerated hydroxyl ion form SBAE.
The mixed bed of R can be used at the end of the primary system of the ultrapure water production system for semiconductors or before or after the existing cartridge polisher or in place of the existing cartridge polisher.

The impurity cations in the conventional ultrapure water are usually at the level of several tens of ppt, but by using the novel hydrogen ion type SACER used in the present invention, the impurity cations are less than 10 ppt, preferably 1 ppt. Ultra-pure water reduced to the level can be obtained. The ultra-pure water obtained by the present invention is suitably used as a wafer cleaning water used for manufacturing a memory of 64 megabits or more for the next generation. At a nuclear power plant, the desalination capacity is equal to or higher than that of the conventional resin by using it for the reactor cooling water makeup water production device or condensate desalination device, and there is no leakage of impurity cations from the resin. Therefore, it is possible to produce ultra-pure water substantially free of impurity cations in the treated water. Hereinafter, the present invention will be described in more detail with reference to examples, but such examples do not limit the scope of the present invention in any way.

Production Example 1 406.8 g of styrene and 93.2 g of divinylbenzene having a purity of 59% were polymerized in a known manner in an aqueous medium containing a dispersant or the like in the presence of a polymerization initiator, and 515 g of a spherical copolymer was obtained. Was manufactured. Then, to this spherical copolymer, ethylene dichloride was added to sufficiently swell the spherical copolymer,
Commercially available 98% concentrated sulfuric acid (Nikko Zinc Co., Ltd.)
) And sulfonated at 120 ° C for 5 hours. After the completion of the reaction, the mother liquor containing the sulfonated form was divided into four 1-liter four-diameter round bottom flasks for 4 minutes (about 40% as the sulfonated form).
0 g) (1) In-line, 18 MΩcm ultrapure water was slowly added with stirring to hydrate the sulfonated product until the pH of the solution became almost neutral. (2) In-line, 15.5 MΩcm of deionized water was added with slow stirring to hydrate the sulfonated product until the pH of the solution became almost neutral. (3) Inline, 10.3 MΩcm
Of deionized water was slowly added with stirring to hydrate the sulfonated product until the pH of the solution became almost neutral. (4)
First, neutralize with the deionized water of (2) and adjust the sulfuric acid concentration of the solution to about 2
After reaching 5%, 9.6 ppm as Na ion, M
11. 1.5 ppm as g ion and 12 as Ca ion.
Using tap water containing 2 ppm, the sulfonated product was hydrated three times while stirring slowly until the pH of the solution became almost neutral. In the above, 15.5 MΩcm and 1
The system for obtaining 0.3 MΩcm of deionized water is a conventional deionized production system, that is, a cation exchange column,
A system consisting of a decarbonation tower, an anion exchange tower, and a monobed was used.

A fixed amount of 20 g of the hydrated hydrogen ion type cation exchange resin of the above (1) to (4) is diluted with ultrapure water of 35% hydrochloric acid containing no impurity cation to obtain 1N hydrochloric acid. One liter of the solution was passed, and impurity cations in the filtrate were quantified by flame photometry. The hydrogen ion type strongly acidic cation exchange resin, which was separately obtained by a conventional method, was calculated from the ion exchange capacity in terms of volume (2.19 eq / liter-resin) and the apparent density (835 g / liter-resin) by calculation as shown below. Was. The results are as follows. (1) resin, (2) resin, (3) resin, (4) resin impurity cation 0.006% 0.04% 0.05% 0.29% equivalent% of (1) The calculation method is shown below 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): 0.1
05 mg / liter Sodium concentration eluted from 20 g (23.95 ml) of sample resin: 0.07 mg / liter Equivalent of sodium contained in 1 liter resin: 0.0
7 × 10 ⁻³ x1000 / 23.95 ÷ 23 = 1.271
x10 ^-4 eq / liter-resin equivalent% of impurity cation = 1.271x10 ^-4 /2.1
9x100 = 0.006

Production Example 2 Sulfonation was carried out with the concentrated sulfuric acid of Production Example 1. After completion of the reaction, the mother liquor containing the sulfonated form was placed in a 1-liter four-diameter round bottom flask for 4 minutes (containing about 400 g as the sulfonated form),
(5) In-line, 18MΩcm ultrapure water was added with slow stirring to hydrate the sulfonated product until the pH of the solution became almost neutral. (6) The concentrated sulfuric acid is diluted to about 50% and 25% with ultrapure water (18 MΩcm), 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) The concentrated sulfuric acid is diluted with ultrapure water (18 MΩcm) to obtain a sulfuric acid concentration of about 2
After the sulfuric acid concentration of the mother liquor is about 30% using 5% sulfuric acid, the pH of the solution is in-line with 7.5 MΩcm of deionized water.
The sulfonated product was hydrated until was almost neutral.
(8) After diluting the above concentrated sulfuric acid with ultrapure water (18 MΩcm) and using a sulfuric acid having a sulfuric acid concentration of about 20% and hydrating it until the sulfuric acid concentration of the mother liquor becomes about 25%, Production Example 1 Hydrated with tap water until the pH of the liquid was almost neutral. The same operation as in Production Example 1 was carried out using a fixed amount of 20 g of the hydrated hydrogen ion type cation exchange resin of the above (5) to (8),
The equivalent% of impurity cations in the resin was determined. The result of
It is as follows. Resin of (5), resin of (6), resin of (7), resin of (8) Equivalent% of impurity cation 0.007% 0.008% 0.1% 0.5%

Example 1 The resins obtained in (1), (2), (4) and (7) of Production Examples 1 and 2 and the hydration step obtained by the method of Production Example 1 (1) were completed. The subsequent resin was made into Na-type resin by adding sodium carbonate by a conventional method, and the resulting resin was passed through 1N hydrochloric acid 10 times per 1 liter of the resin, and then the regenerant residue in the resin was washed with ultrapure water to remove hydrogen. A regenerated SACER ((9) resin) having an ion form conversion of 99.5% was obtained and subjected to the following tests. The following laboratory ultrapure water production system using deionized water as raw water (electrical resistivity 1 at 180 liters / hour at 25 ° C.)
(8 MΩcm of ultrapure water can be supplied).
FIG. 2 shows an outline of the system. Into the cartridge polisher (5 liters) in the flow shown in FIG. 2, each of the above-mentioned resins (1), (2), (4), (7) and (9) and the 1N sodium hydroxide solution SBAE regenerated and refined by passing 10 times the amount of medicine per liter
R (Amberlite IRA-402BL, manufactured by Rohm and Haas Company) as SACER / SBAER
5 liters of each mixed bed resin having a volume ratio of 2/3 (substantially equivalent mixing in the exchange capacity ratio) is added, and SV (Space Velocity) 40 b is applied to the mixed bed resin.
The system was operated at ed volume / hour, and Na ion in ultrapure water (18 MΩcm or more) at the point of use after 1 hour was determined by ion chromatography (manufactured by Dionex, USA) (20 ml of sample water was used in the device). Injection). The results are as follows. Na ion concentration at point of use Resin of (1) Resin of (2) Resin of (4) Resin of (7) Resin of (9) Detection limit 1 ppt or less 2 ppt 10 ppt 5 ppt 15 ppt

Example 2 In the flow shown in FIG. 2, the resin of (2) obtained in Production Example 1 was individually packed in a 5-liter cartridge polisher cylinder to form a single bed, and the resin of (9) was used. After the 5 liter cartridge polisher of mixed bed shown in Fig. 1 was attached in series, the system was operated, and after 1 hour, the Na ion concentration in ultrapure water (18 MΩcm) at the point of use was measured by ion chromatography (manufactured by Dionex, USA). ). As a result, the Na ion concentration is 2p
pt.

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

Example 4 An experiment was conducted using the electronics-related ultrapure water production system shown in FIG. The resin of the cartridge polisher of the secondary pure water production system (30 tons / hour) was mixed with the resin of (2) obtained in Production Example 1 and the regenerated SBER used in Example 3 with a mixed bed having a mixing ratio of 1/2. did. When water flow is started and water quality is stabilized, N
When the a ion concentration was quantified, the conventional 5 ppt to 1 p
It was below the detection limit of pt or less.

Example 5 A bypass line was provided after the mixed-bed polisher of the primary pure water production system of the electronics-related ultrapure water production system shown in FIG. 3, and the resin of (2) obtained in Production Example 1 was used. A single bed of SACER 35 liters was connected and water flow was started. When the water quality was stabilized, the Na ion concentration at the outlet of the single bed was determined to be 2 ppt. In this line, it was 20-30 ppt at the exit of the mixed-bed polisher.

Example 6 In the experimental ultrapure water production system (5 tons / hour) shown in FIG. 4 using industrial water as raw water, a mixed-bed polisher SACER (regeneration type, IR-124) of the primary pure water production system was used. ,
Water regeneration was started by replacing the regeneration rate of 95% and the mixed bed resin (70 liters) with the resin (3) obtained in Production Example 1. When the water quality was stabilized, the Na ion concentration at the outlet of the mixed bed was determined to be 2 ppt. In addition, it was about 20-30 ppt before exchange with the resin of (3).

[Brief description of the drawings]

FIG. 1 is a diagram showing a regeneration efficiency curve of a conventional strongly acidic cation exchange resin.

FIG. 2 is a view showing a schematic flow of a laboratory ultrapure water production system used in Example 1.

FIG. 3 is a diagram showing a flow of an ultrapure water production system used in Examples 4 and 5.

FIG. 4 is a diagram showing a schematic flow of an experimental ultrapure water production system used in Example 6.

Continuation of front page (56) References JP-A-5-209012 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C12F 1/42 B01J 39/00-49/02

Claims (1)

(57) [Claims] 1) a step of producing a crosslinked polymer, 2) a step of sulfonating the crosslinked polymer in the presence of a sulfonating reagent, and 3) a step of removing impurity cations other than hydrogen ions.
5M at 25 ℃ electrical resistivity without external
Ωcm or more with water or diluted sulfuric acid followed by 2
A hydrogen ion type strongly acidic cation exchange resin produced by a method including a step of hydrating with water having an electric specific resistance of 5 MΩcm or more at 5 ° C., wherein impurity cations other than hydrogen ions are contained in the ion exchange resin. A single bed of a hydrogen ion type strongly acidic cation exchange resin having 0.1 equivalent% or less of the total exchange equivalents, or a mixed bed of the hydrogen ion type strongly acidic cation exchange resin and a regenerative strong basic anion exchange resin A method for producing ultrapure water including a step of passing water through.