JP2003010660A - Ultrapure water specific resistance adjustment device and adjustment method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] Fluctuation of resistivity value caused by reverse diffusion of dissolved gas in ultrapure water raw water To solve these problems, a simple and compact ultrapure water ratio without a control mechanism is required. An apparatus and method for adjusting a resistance value. SOLUTION: An apparatus for adjusting the specific resistance of ultrapure water by flowing carbon dioxide gas or ammonia through a gas permeable membrane and dissolving the gas in ultrapure water. With the function of leaking a part of the supplied carbon dioxide or ammonia gas to the outside of the module to discharge dissolved oxygen and dissolved nitrogen that diffuse back to the carbon dioxide or ammonia gas side through the module. Further, an apparatus capable of easily adjusting the specific resistance without being affected by fluctuations in the flow rate of ultrapure water, and an adjustment method using the apparatus.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for adjusting the specific resistance of ultrapure water used as cleaning water especially in the fields of semiconductors and liquid crystals.

[0002]

2. Description of the Related Art In the process of manufacturing semiconductors and liquid crystals, when using ultrapure water (specific resistance ≧ 18 MΩ · cm) to wash photomask substrates, silicon wafers, and glass plates, when dicing machines are used to cut wafers. In addition, it is widely known that static electricity is generated due to the high specific resistance of ultrapure water, which causes dielectric breakdown or adsorption of fine particles, which significantly affects the product yield of substrates. There is. Therefore, in order to eliminate such an adverse effect, a method of mounting a magnesium mesh in the ultrapure water flow path to reduce the specific resistance of ultrapure water is known.

Further, as a method of dissolving carbon dioxide gas in ultrapure water using a hydrophobic porous hollow fiber membrane module and lowering the specific resistance by carbonate ions generated by dissociation equilibrium, the specific resistance of ultrapure water is used. Adjustment device (Japanese Patent Publication No. 5-21841)
Japanese Patent Laid-Open Publication No. Heisei 7), a method and an apparatus for adjusting the resistivity of ultrapure water (Japanese Patent Laid-Open No. Hei 7 (1999) -1999).
No. 60082) is proposed.

Further, in the steps such as cleaning of silicon wafers and dicing, the flow rate of ultrapure water changes drastically, and it is required that the specific resistance does not change even if the flow rate changes. In extreme cases, it is required to cope with flow rate fluctuations that occur every few seconds. As a method of controlling the specific resistance constant even if the flow rate of ultrapure water changes, "Science of ultrapure water" (edited by Semiconductor Technology Research Group, published by Realize Co., Ltd.) describes the ratio after dissolution of carbon dioxide gas. A method of measuring resistance and performing feedback control of the carbon dioxide gas flow rate (page 392) and a method of measuring ultrapure water flow rate and feedforward controlling the carbon dioxide gas flow rate by a mass flow controller (page 401) are described.

[0005]

[Problems to be Solved by the Invention]
In the method of controlling the flow rate of carbon dioxide gas described in JP-A-21841 and the method of feedback controlling the flow rate of carbon dioxide gas of the method described in "Science of ultrapure water", it is impossible to follow the flow rate fluctuation in a short time. In addition, the method of feedforward controlling the flow rate of carbon dioxide gas from the measured value of the flow rate of ultrapure water in the method described in "Science of ultrapure water" requires an expensive microcomputer circuit and an expensive mass flow controller. Is not satisfactory either. Japanese Patent Laid-Open No. 7-6008
The publication No. 2 does not include the idea of controlling the specific resistance value to a constant value when the flow rate of ultrapure water changes. Further, only by setting the carbon dioxide pressure, it is unavoidable that the specific resistance value fluctuates when the flow rate of ultrapure water changes. In addition, a slight amount of dissolved oxygen and dissolved nitrogen dissolved in raw water of ultrapure water is diffused back to carbon dioxide or ammonia side through the gas permeable membrane, thereby changing the partial pressure of carbon dioxide or ammonia. It was not sufficient to follow the changes in the specific resistance that occurred.

The object of the present invention is to solve these problems, in particular, to solve the fluctuation of the specific resistance value due to the back diffusion of the dissolved gas in the raw water of ultrapure water, and to provide a simple and compact supercomputer which does not require a control mechanism. An object is to provide an apparatus and method for adjusting the specific resistance value of pure water.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that dissolved oxygen and dissolved nitrogen that diffuse back from ultrapure water to the side of carbon dioxide or ammonia through the membrane are dissolved oxygen and dissolved nitrogen. For the purpose of discharging, it was found that the fluctuation of the specific resistance can be controlled according to the change of the flow rate of ultrapure water by using the discharging device capable of adjusting the discharge amount of the supplied carbon dioxide gas or ammonia gas, and the invention was completed.

That is, the present invention comprises a membrane module having a housing in which an ultrapure water passage portion made of a hollow fiber membrane and a carbon dioxide gas or ammonia gas passage portion are formed in a housing, and communicates with the ultrapure water passage portion. Ultra pure water raw water inlet to
The distribution unit includes a distribution unit provided in an intermediate unit connecting them, and a resistivity adjusting ultrapure water outlet communicating with the ultrapure water passage unit and a confluence unit provided in an intermediate unit connecting them are provided. A bypass channel connecting the section and the confluence section,
The distribution unit distributes the ultrapure water raw water, which is fed from the ultrapure water raw water inlet, to the ultrapure water passage and the bypass flow passage at a constant flow rate ratio, and the gas permeable membrane separates the ultrapure water passage. It has the ability to dissolve carbon dioxide gas or ammonia gas in the passing ultrapure water to a concentration of 90% or more of the equilibrium concentration determined by the gas pressure and the water temperature. A resistivity adjusting device is provided.

Further, according to the present invention, in order to adjust the specific resistance of ultrapure water, carbon dioxide gas or ammonia gas is brought into contact with ultrapure water through a gas permeable membrane, and the ultrapure water is supplied with carbon dioxide gas or ammonia gas. An apparatus for producing ultrapure water having a predetermined specific resistance value by supplying the desired specific resistance value,
As a membrane module equipped with a gas permeable membrane, carbon dioxide or ammonia gas is added to ultra-pure water with a variable flow rate that is assumed in advance, and 90% of the equilibrium concentration is determined by the gas pressure and water temperature.
Equipped with a membrane module capable of dissolving up to the above concentration, by which ultra pure carbon dioxide or ammonia gas is dissolved so that the specific resistance value becomes constant even if the flow rate of the ultrapure water supplied changes. Equipped with means for producing water,
For the purpose of discharging the dissolved oxygen and dissolved nitrogen that diffuse back from the ultrapure water to the carbon dioxide or ammonia gas side through the membrane,
It has a function to keep part of the supplied carbon dioxide or ammonia gas out of the module and keep the concentration of carbon dioxide or ammonia gas constant, and to the raw water of ultrapure water (carbon dioxide or ammonia gas undissolved ultrapure water) side. It is equipped with a distributor and a bypass channel, and distributes ultrapure water to the membrane module and the bypass channel at a constant flow rate ratio. The generated carbon dioxide or ammonia gas dissolved ultrapure water and the ultrapure water from the bypass channel. There is also provided an apparatus for adjusting the resistivity of ultrapure water, which comprises a means for merging and uniformly mixing with each other, and which dilutes the ultrapure water after mixing to a final target resistivity value.

Further, according to the present invention, a step of distributing raw water of ultrapure water at a constant flow rate ratio to two streams, and carbon dioxide pressure or ammonia gas supplied to one of the streams of ultrapure water via a gas permeable membrane. A step of dissolving carbon dioxide gas or ammonia gas to a carbon dioxide gas concentration or ammonia gas concentration of 90% or more of the equilibrium concentration determined by the pressure and water temperature to generate resistivity-adjusted ultrapure water. For the purpose of discharging dissolved oxygen and dissolved nitrogen that diffuse back to the carbon dioxide gas or ammonia gas side via, leak a part of the supplied carbon dioxide gas or ammonia gas to the outside of the module to reduce the carbon dioxide concentration or ammonia concentration. The specific resistance of ultrapure water, which has a step of maintaining a constant value and a step of joining the carbon dioxide gas or ammonia gas-dissolved ultrapure water and the flow of the other raw water of ultrapure water Also provides an adjustment method.

Further, according to the present invention, in order to produce the amount of ultrapure water whose resistivity has been adjusted in accordance with the fluctuating consumption amount, in the method of adjusting the resistivity of ultrapure water, the ultrapure water supplied in accordance with the consumption amount is supplied. Sustainable raw water has a relatively large and small amount depending on the distribution device.
It is split into two streams at a constant flow rate ratio, and one stream is supplied to a hollow fiber membrane module for flowing ultrapure water and carbon dioxide gas or ammonia gas across the membrane to dissolve a small volume of carbon dioxide gas or ammonia gas. Water is generated within the range of fluctuating flow rate assumed in advance, and at that time, it is supplied for the purpose of discharging dissolved oxygen and dissolved nitrogen from ultrapure water which diffuses back to carbon dioxide gas or ammonia gas side through the membrane. Part of the carbon dioxide gas or ammonia gas generated is leaked to the outside of the module to have a function of keeping the carbon dioxide gas concentration or ammonia concentration constant, and the carbon dioxide gas or ammonia gas-dissolved ultrapure water is used as carbon dioxide gas at that time. Carbon dioxide concentration or ammonia gas concentration of 90% or more of the equilibrium concentration determined by the pressure or ammonia gas pressure and water temperature, and the carbon dioxide or ammonia gas dissolved ultrapure water Is combined with ultrapure Suwon water divided into large flow uniformly mixed, and ultrapure water adjusted to a predetermined specific resistance, also provides a specific resistance adjusting method of ultrapure water.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Typical and best modes of the embodiments of the present invention will be concretely shown in Examples below, and the outline thereof is as follows.

FIG. 1 is an example of an apparatus suitable for the present invention.

The present invention proposes a simple and compact resistivity adjusting device and method for ultrapure water that does not have a complicated control mechanism. Water Raw water is divided into two streams, gas is added to one of the streams to generate ultrapure water in which a small amount of carbon dioxide gas or ammonia gas is dissolved, and this is combined with large amount of ultrapure water. An apparatus and method for adjusting specific resistance by uniformly mixing and diluting.

In order to enhance the efficiency of dissolving this carbon dioxide gas or ammonia gas, a membrane module is arranged in the apparatus, and carbon dioxide gas or ammonia gas is supplied and dissolved into ultrapure water through this membrane to obtain ultrapure water. The concentration of carbon dioxide gas or ammonia gas is leaked to the outside of the module by discharging a part of the supplied carbon dioxide gas or ammonia gas for the purpose of discharging dissolved oxygen and dissolved nitrogen which diffuse back to the carbon dioxide gas or ammonia gas side through the membrane. It is a further proposal to keep constant.

The gas permeable membrane used in the present invention is not particularly limited in material, structure and morphology as long as it has a high carbon dioxide or ammonia gas permeation rate, but the membrane material is preferably a highly hydrophobic material. For example, polyethylene resin,
Polypropylene resin, polytetrafluoroethylene,
Perfluoroalkoxy fluororesins, various fluororesins such as polyhexafluoropropylene, polybutene resins,
Materials such as silicone resins and poly (4-methylpentene-1) resins are preferred. Further, as the membrane structure, a microporous membrane, a homogeneous membrane, a heterogeneous membrane, a composite membrane, a polypropylene microporous membrane, a sandwich membrane of a thin film such as urethane, or a so-called sandwich membrane can be used. Examples of the form of the membrane include a flat membrane and a hollow fiber membrane, and the hollow fiber membrane is preferable in terms of gas dissolution efficiency.

As the membrane material, for example, resins such as polyethylene resin, polypropylene resin and polyvinylidene fluoride resin have low gas permeability, so that they are used for dissolving carbon dioxide gas or ammonia gas. Must have a microporous structure, and carbon dioxide or ammonia gas must be permeable through the porous portion. Compared with the membranes made of these materials, this heterogeneous membrane made of poly (4-methylpentene-1) resin has sufficiently high gas permeability, and the dense layer has a sufficiently thin film thickness. The entire membrane surface can contribute to permeation of carbon dioxide gas or ammonia gas, and as a result, the substantial membrane area becomes large, which is extremely preferable.

The hollow fiber heterogeneous membrane made of the above poly (4-methylpentene-1) resin is most preferable because it has excellent permeability to carbon dioxide gas or ammonia gas and high water vapor barrier property. For this heterogeneous film, for example, Japanese Patent Publication No. 2
-38250, Japanese Patent Publication No. 2-54377, Japanese Patent Publication No. 4-15014, Japanese Patent Publication No. 4-50053, Japanese Patent Application Laid-Open No. 5-6656, etc. The heterogeneous membrane made of methylpentene-1) resin has a very small pore size and open area of communicating pores penetrating the membrane wall while having high gas permeation performance, and therefore, compared with a microporous membrane of PP or PE. It has extremely excellent water vapor barrier properties.

Carbon dioxide permeation rate or ammonia of the hollow fiber membrane
The near gas permeation rate is the carbon dioxide gas that permeates the hollow fiber membrane or
Has a sufficient permeation rate of ammonia gas,
When the flow rate of ultrapure water fluctuates,
1 × 10 from the point that the resistivity value does not fluctuate easily^-6[cm^Three/cm
^Two・ Sec · cmHg] or more is preferable. Also, with gauge pressure
0.1 kg / cm^TwoCarbon dioxide or ammonia gas
Supply carbon dioxide or ammonia gas
Become mixed with the ultrapure water, or conversely, the ultrapure water becomes carbon dioxide gas or
Has a problem that it permeates to the ammonia gas side,
From the viewpoint of not having these problems, the carbon dioxide permeation rate of the hollow fiber membrane
Degree or ammonia gas permeation rate is 10 [cm ^Three/cm^Two・ S
ec · cmHg] or less is preferable. Generally carbon dioxide or Anne
If the monia gas becomes bubbles, the specific resistance value can be adjusted to a constant value.
Becomes difficult.

As for the housing in which the hollow fiber membrane is disposed, any material may be used as long as the above-mentioned ultrapure water does not elute impurities.

Specific examples include polyolefins such as polyethylene, polypropylene and poly-4-methylpentene 1, fluorine-based compounds such as polyvinylidene fluoride and polytetrafluoroethylene, polyether ether ketone, polyether ketone, polyether sulfone. Examples include engineering plastics such as polysulfone, and clean vinyl chloride, which are used as piping materials for ultrapure water because of their low elution.

As a hollow fiber membrane module structure, a plurality of hollow fiber membranes are converged and arranged in a housing, and carbon dioxide gas or ammonia gas is supplied to the space between the outside of the hollow fiber membranes and the housing to form a hollow fiber membrane. In addition to the internal perfusion type in which ultrapure water is flown inside, the external perfusion in which ultrapure water is flown outside the hollow fiber and carbon dioxide or ammonia gas is flown inside is disclosed in Japanese Patent Publication No. 5-21841. Types are also possible.

In the case of the external perfusion type, in order to prevent uneven flow (channeling) of water due to uneven filling of the hollow fibers in the housing, the hollow fibers are hollow fibers or other fibers. It is effective to form a sheet-like material, for example, a sheet-like material, which is formed into a blind shape by using, and to incorporate it into the housing in the state of a superposed body, a wound body, and a converging body. It is also possible to adopt an appropriate shape such as incorporating a three-dimensional structure in which the hollow fiber is wound around a cylindrical core.

Whichever type of internal perfusion and external perfusion is adopted, either structure may be used for the purpose of lowering the specific resistance value by dissolving carbon dioxide gas or ammonia gas in ultrapure water. When it is necessary to follow large fluctuations in the flow rate of water dissolved in carbon dioxide or ammonia gas, it is possible to use ultrapure water efficiently considering the high-speed response to the set resistivity value, accuracy, reproducibility, and stability. It is necessary to dissolve carbon dioxide or ammonia gas evenly and uniformly,
From these points, the internal perfusion type hollow fiber membrane module is preferable.

As a distributor for distributing the raw water of ultrapure water to the hollow fiber membrane module and the bypass conduit, the flow ratio of the two flows is always constant even if the total flow rate of the two separated flows changes. There is nothing to be specified as long as it can be divided into two streams, and it is possible to simply use piping teeth or a branch valve. However, the distribution ratio may be controlled by a flow meter with a precision valve or an orifice that allows only a specified amount of water to flow.

From the aspect of the material of the distributor, it is necessary to consider the elution of impurities into ultrapure water. From that aspect, from the viewpoint of fluorine polymer, clean vinyl chloride, ultrapure water compatible austenitic stainless steel, The use of inorganic glass or the like is preferred.

As a merging device for merging the generated carbon dioxide gas or ammonia gas-dissolved ultrapure water and the raw water that has passed through the bypass pipe, there is nothing to define if there is an inlet for merging two streams. Include plumbing teases.

It is more preferable to dispose a static mixer on the downstream side of the confluence device for the purpose of uniformly mixing the two confluent flows. Ultra pure water mixed and diluted is obtained. It is preferable to use fluorine-based polymers, clean vinyl chloride, austenitic stainless steel compatible with ultrapure water, inorganic glass and the like in consideration of the elution of impurities into ultrapure water with regard to the materials of the confluence device and static mixer.

In the prior art, precise automatic control of the flow rate or pressure of carbon dioxide was performed, but in the present invention, the carbon dioxide concentration or ammonia gas concentration may be maintained at a certain constant value, so the valve altitude No need for automatic control. The required carbon dioxide gas concentration or ammonia gas concentration is 90% of the equilibrium concentration that is determined in proportion to the water temperature of the ultrapure water in which the carbon dioxide gas or ammonia gas is dissolved and the pressure of the supplied carbon dioxide gas or ammonia gas according to Henry's law. It is a value that is equal to or higher than%, and is substantially constant. For example, a suitable pressure of carbon dioxide gas or ammonia gas in the present invention is 0.015 to 0.15 MPa.

By supplying the carbon dioxide gas or the ammonia gas at a constant pressure by the pressure regulating valve, the supply amount according to the flow rate fluctuation of the ultrapure water in the membrane module is maintained, and the constant concentration of the carbon dioxide gas or the ammonia gas is maintained. Be drunk

Regarding the carbon dioxide gas or ammonia gas pressure regulating valve, as long as it is filtered in advance so that the contamination in the gas on the supply source side (temporary side) does not adhere to the hollow fiber membrane, any structure or material It is not necessary to specify the model, etc., and those generally used in the semiconductor and liquid crystal fields may be used. For example, a pressure control valve (regulator) such as a pressure regulating valve, a bellows pressure valve, a pressure regulator, or a back pressure valve can be used.

The bypass pipe may be a pipe through which ultrapure water flows and the wall of the pipe does not allow carbon dioxide gas or ammonia gas to pass therethrough, and the ultrapure water flowed for two minutes is kept constant at a predetermined ratio. If so, its shape is not particularly limited. or,
The number of bypass pipelines is not necessarily limited to one.

Since ultrapure water passes through the bypass pipe,
From the same viewpoint as in the previous term, the material of the tube is preferably austenitic stainless steel or inorganic glass compatible with ultrapure water rather than plastic or resin.

Next, the specific resistance adjusting method of the present invention will be described.

Up to now, various mechanisms have been used to dissolve carbon dioxide or ammonia gas in ultrapure water, carbon dioxide concentration or ammonia gas concentration and specific resistance value when carbon dioxide or ammonia gas is directly dissolved in ultrapure water. The relationship is known.

Therefore, for the purpose of adjusting the specific resistance of ultrapure water,
Dissolving a predetermined amount of carbon dioxide gas in ultrapure water through a hollow fiber membrane has been proposed by Japanese Patent Publication No. 5-21841 and the feedforward method and feedback method described in "Science of Ultrapure Water". However, when the amount of ultrapure water fluctuates instantaneously, it is actually difficult to make it respond and follow and control a predetermined specific resistance value.

However, the present inventors divided the ultrapure water raw water into two streams, and used ultrapure water in which carbon dioxide gas or ammonia gas was dissolved at a concentration higher than the concentration of carbon dioxide gas or ammonia gas to give a specific resistance value. It was found that the specific resistance can be adjusted by a method of diluting with pure water and maintaining a constant ratio of the pure water for uniform mixing.

That is, the important point of the present invention is to divide the raw water of ultrapure water supplied according to the amount of consumption into two streams having a large or small flow rate by a distribution device at a constant ratio, and separate ultrapure water and carbon dioxide through the membrane. Gas or ammonia gas is supplied to one of the hollow fiber membrane modules to generate a small flow rate of carbon dioxide gas or ammonia gas dissolved water at a high carbon dioxide concentration or ammonia gas concentration, and the carbon dioxide or ammonia gas is dissolved. The method of merging water into raw water divided into a large flow rate and mixing them uniformly is to easily obtain resistivity-adjusted ultrapure water, but further diversion is carried out in the piping system in the device, It may be implemented by providing a bypass line in the hollow fiber membrane module or by several methods. If the carbon dioxide gas or ammonia gas is dissolved under the above-mentioned preferable carbon dioxide gas pressure or ammonia gas pressure at room temperature, the equilibrium concentration carbon dioxide gas or ammonia gas under that condition is dissolved to become a substantially constant value, and the specific resistance adjustment It will be easier to do. In addition, according to this method, the raw water of ultrapure water is divided by a distributor into two streams having different flow rates at a constant ratio, and the concentration of carbon dioxide gas or ammonia gas supplied to the hollow fiber membrane module is kept constant. It is possible to adjust the specific resistance by doing so, but the dissolved oxygen and dissolved nitrogen of the gas partial pressure corresponding to the pressure reversely diffuse from the ultrapure water side to the carbon dioxide gas or ammonia gas side through the hollow fiber membrane. As a result, a change in concentration occurs, so that the set resistivity value changes over time. Therefore, it is possible to keep the specific resistance more constant by leaking a part of the supplied carbon dioxide gas or ammonia gas to the outside of the module to add a function of keeping the carbon dioxide gas or ammonia gas concentration constant. The amount of carbon dioxide gas or ammonia gas leaked is preferably as small as possible because it affects the amount of gas used, and it is preferable to leak a minimum flow rate that does not cause a change in gas concentration. The actual flow rate used depends on the flow rate of ultrapure water used, but is preferably about 2 to 10 ml / min. In order to further reduce the amount of carbon dioxide gas or ammonia gas used, it is more preferable to install a device for intermittently opening and closing the valve in the preceding stage.

As a device for adding a function of leaking a part of the supplied carbon dioxide gas or ammonia gas to the outside of the module to keep the carbon dioxide gas or ammonia gas concentration constant, an extremely small leak flow rate is always kept constant. It is necessary to maintain the state, and it is preferable to use a flow meter equipped with a precision valve or an orifice that allows only a specified amount of water to flow. As a device for intermittently opening and closing the valve in the preceding stage, a device in which a solenoid valve, an air operated valve and the like are combined with a timer is preferable.

The diversion ratio of the ultrapure water for producing the carbon dioxide or ammonia gas-dissolved ultrapure water and the ultrapure water for the raw water flowing through the bypass pipe varies greatly depending on the desired specific resistance value. The range of the range to be controlled greatly depends on the type of semiconductor or liquid crystal device to which ultrapure water is used and the cleaning process used.

Therefore, it is extremely effective to appropriately change the magnitude relationship of the flow rate ratio according to the purpose of use of the resistivity adjusting ultrapure water.

In the recent wafer cleaning process in the fields of semiconductors and liquid crystals, a specific resistance value of 0.1 [MΩ · cm] or more is particularly desired. In this case, the small flow rate side (hollow fiber membrane module side).
It suffices that the ratio of the flow rate of the carbon dioxide gas or ammonia gas dissolved water to the flow rate of the ultrapure water on the large flow rate side (bypass side) is smaller than (small flow rate side) / (large flow rate side) = 1/50.

[0043]

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to this and is not limited.

In these examples, the specific resistance of ultrapure water was measured using a commercially available specific resistance measuring instrument (CE-480R manufactured by COS).

Raw water is 18.2 MΩ · c at 25 ° C.
Using ultrapure water with a specific resistance of m, the flow rate of ultrapure water is 4 to 8
Liter / min. Fluctuated between. The flow rate maintenance time was changed stepwise at 30 seconds. The supply water pressure is 0.2
It was set to MPa.

7 m ^{3 for} carbon dioxide and ammonia gas sources
A carbon dioxide gas cylinder and an ammonia gas cylinder were prepared, and the pressure of carbon dioxide gas or ammonia gas to be supplied to the membrane module was set to 0.1 [MPa] with a two-stage pressure regulator and a pressure regulating valve.

As a device for adding a function of leaking a part of carbon dioxide gas or ammonia gas to the outside of the module to keep the concentration of carbon dioxide gas or ammonia gas constant, a speed controller capable of adjusting a small flow rate is used. Was set to 2 ml / min.

Example 1 As a hollow fiber membrane module, poly-4-methylpentene-1 was used as a material, and yarns having an inner diameter of 200 μm and an outer diameter of 250 μm were converged, and both ends of the yarn were made into resin in a housing made of clean vinyl chloride resin. Internal perfusion type hollow fiber module for gas supply 1 having a membrane area of 0.5 m ²
(Dainippon Ink and Chemicals, Inc. SEPAREL PF
-001R) was obtained. The carbon dioxide permeation rate of the hollow fiber membrane was 3.5 × 10 ⁻⁵ [cm ³ / cm ² · sec · cmHg].
This is common to the following examples and comparative examples.

FIG. 1 is a schematic view of an apparatus of Example 1 incorporating the hollow fiber membrane module 1.

The apparatus of Example 1 is the hollow fiber membrane module 1
Is provided in the middle of the carbon dioxide gas dissolution channel 2. On the upstream side of the hollow fiber membrane module 1, one end of the bypass conduit 3 is connected to the carbon dioxide gas dissolution passage 2 via the distributor 5. The other end of the bypass pipe line 3 is connected to the carbon dioxide gas dissolving circuit 2 via a merging device 6 on the downstream side of the hollow fiber membrane module 1. An ultrapure water raw water inlet 7 is provided on the upstream side of the distributor 5. An outlet 8 for ultrapure water that has undergone a specific resistance adjustment process is provided on the downstream side of the merging device 6. Carbon dioxide gas dissolution channel 2 between the hollow fiber membrane module 1 and the distribution device 5
And the bypass line 3 have flow meters FI1 and FI, respectively.
Two are provided. A carbon dioxide gas supply port 9 is provided in the center of the hollow fiber membrane module 1, and a carbon dioxide gas flow path 4 is provided therein.
Are connected. A pressure regulating valve 10 is provided in the middle of the carbon dioxide gas flow path 4. A carbon dioxide gas pressure gauge PI is provided in the carbon dioxide gas flow path 4 between the carbon dioxide gas supply port 9 and the pressure regulating valve 10. A carbon dioxide gas exhaust port 11 is provided at the center of the hollow fiber membrane module 1, and a speed controller 12 capable of adjusting a small flow rate is provided.

The device of Example 1 operates as follows. Raw ultrapure water is introduced into the apparatus through the raw ultrapure water inlet 7.
The raw water of ultrapure water is distributed by the distributor 5 into a flow having a relatively small flow rate and a flow having a relatively large flow rate. The flow having a relatively small flow rate is guided to the carbon dioxide gas dissolution channel 2 and further to the inside of the hollow fiber membrane in the hollow fiber membrane module 1. The flow having a relatively large flow rate is guided to the bypass line 3. Carbon dioxide is introduced into the carbon dioxide flow path 4. This carbon dioxide gas is adjusted to a constant pressure by the pressure regulating valve 10, then introduced into the hollow fiber membrane module from the carbon dioxide gas inlet 9, permeates the hollow fiber membrane, and is dissolved in the ultrapure water raw water in the hollow fiber. It Here, the ultrapure water raw water in the hollow fiber membrane becomes carbon dioxide dissolved ultrapure water. This carbon dioxide-dissolved ultrapure water is introduced into the flow path on the outlet side of the hollow fiber membrane module 1 and merges with the flow of relatively large flow rate from the bypass conduit 3 by the merging device 6 to adjust the target specific resistance. Ultrapure water is obtained. At this time, 2 ml of carbon dioxide with the speed controller 12
Slow leak for about / min.

Using the apparatus shown in FIG. 1, the flow rate of the whole ultrapure water was varied and the specific resistance value of the specific resistance adjusted ultrapure water was measured. Table 1 shows the results of changes in the specific resistance value of this device. Almost no discrepancy was observed in tracking the flow rate fluctuation.

Example 2 In this example, an internally perfused hollow fiber membrane module 13 (SE manufactured by Dainippon Ink and Chemicals, Inc.) with a bypass line added was used.
PAREL PF-001R5) was used. FIG. 2 shows a cross-sectional view of the hollow fiber membrane module 13.

The hollow fiber membrane module 13 is an internal perfusion type module in which the hollow fiber membrane portion 20 and the cylindrical portion which becomes the bypass conduit 19 are incorporated in a housing made of clean vinyl chloride resin. The hollow fiber membrane portion 20 is made of poly-4-methylpentene-1 and has an inner diameter of 200 μm.
m, an outer diameter of 250 μm is formed by converging hollow fiber membranes,
It has a membrane area of 0.5 m ² . Both ends of the hollow fiber membrane portion 20 are hardened with resin to form an adhesive sealing portion 23 for adhesively sealing the hollow fiber membrane and the housing. The bypass line 19 is a cylinder made of SUS316 compatible with ultrapure water. In the apparatus of the second embodiment, the supply ratio of raw ultrapure water to the bypass conduit 19 to the hollow fiber membrane portion 20 is 50 times.
The housing of the hollow fiber membrane module 13 is provided with a carbon dioxide gas supply port 22 and a gas exhaust port 24, and a speed controller 25 is provided at the exhaust port.

In this hollow fiber membrane module 13, the membrane end opening of the hollow fiber membrane portion 20 and the opening of the bypass conduit 19 are arranged side by side at both ends of the housing. Both ends of the housing are covered with end caps 21, respectively. As a result, the ultrapure water distributor 15 and the junction 16 are formed inside the respective end caps 21. The end cap 21 forming the confluence 16 is provided with an outlet 18 for ultrapure water that has undergone a specific resistance adjustment process. Therefore,
In the hollow fiber membrane module 13 of this embodiment, the distribution device, the hollow fiber membrane module, the bypass conduit, the confluence device, and the like are integrated. The supply ratio of the ultrapure raw water to the hollow membrane portion 20 and the bypass pipe is determined by the distribution unit 1
It is reflected in the ratio of the total area of the openings of the hollow fiber membrane portion 20 on the fifth side and the opening area of the bypass conduit 19.

The apparatus of Example 2 operates as follows. The raw water for ultrapure water is supplied from the raw water inlet 17 for ultrapure water to the distributor 15 in the apparatus.
Can be put in. Raw ultrapure water is introduced into the hollow fiber membrane of the hollow fiber membrane portion 20 and the bypass conduit at a ratio of 1:50, respectively. The carbon dioxide gas is introduced into the hollow fiber membrane module 1 from the carbon dioxide gas inlet 22 and contacts the outer surface of the hollow fiber membrane. Carbon dioxide gas further permeates the hollow fiber membrane and is dissolved in the ultrapure raw water in the hollow fiber membrane. At this time, by adjusting the carbon dioxide gas to 2 ml / min with a speed controller and exhausting it, the carbon dioxide gas partial pressure can be kept constant, and the ultrapure water raw water becomes stable carbon dioxide gas-dissolved water. The carbon dioxide gas-dissolved water is guided to the merging section 16, where it merges with the ultrapure pure water from the bypass conduit 19. The target resistivity-adjusted ultrapure water thus obtained is taken out from the outlet 18.

Using the apparatus of FIG. 2, the specific resistance value of the ultrapure water was measured by varying the flow rate of the entire ultrapure water.
Table 1 shows the results of changes in the specific resistance value of this device. Almost no discrepancy was observed in tracking the flow rate fluctuation.

Example 3 The hollow fiber membrane module of Example 3 was the same as the hollow fiber membrane module of Example 2 except that the supply ratio of raw ultrapure water to the bypass line to the hollow fiber membrane portion was 150 times. An internal perfusion type module (SEPAREL PF-001R5 manufactured by Dainippon Ink and Chemicals, Inc.) having the same configuration was used.

Using this apparatus, the flow rate of the whole ultrapure water was varied and the specific resistance value of the specific resistance adjusted ultrapure water was measured. Table 1
Shows the change in the specific resistance value by this device. Almost no discrepancy was observed in tracking the flow rate fluctuation.

Example 4 Using the same hollow fiber membrane module as in the apparatus of Example 1, the side where carbon dioxide gas and ultrapure water flow into this hollow fiber membrane module is opposite to that of Example 1, and the hollow fiber membrane An apparatus of Example 4 was prepared by flowing carbon dioxide gas inside and ultrapure water outside the hollow fiber membrane. Using the apparatus of this Example 4, the flow rate of the entire ultrapure water was varied and the specific resistance value of the resistivity adjusted ultrapure water was measured. The results are shown in Table 1. Almost no discrepancy was observed in tracking the flow rate fluctuation.

Example 5 An apparatus of Example 5 was prepared in the same manner as in Example 1 except that ammonia gas was used instead of carbon dioxide gas. Example 5
Using the apparatus described in (1), the flow rate of the entire ultrapure water was varied to measure the specific resistance value of the specific resistance adjusted ultrapure water. The results are shown in Table 1. Almost no discrepancy was observed in tracking the flow rate fluctuation.

Comparative Example As a comparative example, the device of Example 1 with the speed controller attached to the carbon dioxide gas exhaust port removed and a stop valve attached was used as the device. When the raw water of ultrapure water is 1 liter / min, the specific resistance value is 0.1M
Although it was attempted to adjust the resistance value to Ω · cm, the specific resistance value became 0.15 MΩ · cm after a while, and the specific resistance value could not be adjusted. Then, the opening of the needle valve was maintained as it was, and the flow rate of ultrapure water was changed between 2 and 8 liters / min to measure the specific resistance value of the specific resistance adjusted ultrapure water. Table 1 shows the change in the specific resistance value at that time.

Next, when the raw ultrapure water is 2 liters / min, the opening of the needle valve is adjusted so that the set specific resistance value is 0.2 MΩ · cm, and the raw pure water flow rate is 2 to 8. The specific resistance value of the specific resistance-adjusted ultrapure water was measured while varying between liters / min. The results are also shown in Table 1.

In this comparative example, the deviation of the follow-up with respect to the flow rate fluctuation was remarkably recognized at any set specific resistance value.

[0065]

[Table 1]

[0066]

According to the present invention, the raw water of ultrapure water supplied according to the amount of consumption is divided into two streams having different flow rates at a constant ratio by the distribution device, and one stream is supplied to the hollow fiber module. The specific resistance can be easily adjusted by generating a small flow rate of carbon dioxide gas or ammonia gas dissolved water, and joining the carbon dioxide gas or ammonia gas dissolved water to the raw water, which was divided into a large flow rate, and mixing it uniformly. Becomes

When used in a wet process washing machine on the downstream side of the apparatus, even if the amount of ultrapure water used fluctuates instantaneously,
It is possible to easily and stably obtain ultrapure water having a desired specific resistance value without using any control device.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of an apparatus for adjusting the resistivity of ultrapure water for the purpose of adjusting the resistivity according to the present invention.

FIG. 2 is a vertical cross-sectional view of an internal perfusion type hollow fiber membrane module according to the present invention in which a bypass conduit 19 and a hollow fiber membrane 20 are converged and arranged.

[Explanation of symbols]

PI Carbon dioxide or ammonia gas pressure meter FI1 Carbon dioxide or ammonia gas dissolved water flow meter FI2 for ultra-pure water small flow rate side bypass flow meter 1 for ultra-pure water large flow rate 1 Hollow fiber membrane for carbon dioxide or ammonia gas supply Module 2 Carbon dioxide or ammonia gas dissolution channel 3 Bypass pipeline 4 Carbon dioxide or ammonia gas channel 5 Distributor 6 Combiner 7 Ultra pure water raw water inlet 8 Resistivity adjustment ultra pure water outlet 9 Carbon dioxide or ammonia gas supply Port 10 Pressure regulating valve 11 Carbon dioxide gas or ammonia gas exhaust port 12 Speed controller 13 Hollow fiber membrane module 15 for supplying carbon dioxide gas or ammonia gas Distributor 16 Confluence part 17 Ultrapure water raw water inlet 18 Specific resistance adjustment ultrapure water outlet 19 Bypass conduit 20 Hollow fiber membrane portion 21 End cap 22 Carbon dioxide gas or ammonia gas Exhaust ports 23 adhesive sealing portion 24 carbon dioxide or ammonia gas outlet 25 Speed Controller

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Misao Takeuchi             362 Shimotorida, Kisarazu City, Chiba Prefecture F-term (reference) 4D006 GA32 HA01 KA12 KE19Q                       MA01 MA33 MB03 MC22 MC28                       MC29 MC30 MC65 PA01 PB12                       PB64 PB70 PC02                 4D011 AA16 AA17 AD03 AD06                 4G035 AA01 AE01 AE13 AE17

Claims (10)

[Claims] 1. An ultrapure water which is provided with a membrane module having a housing in which an ultrapure water passage portion made of a hollow fiber membrane and a carbon dioxide gas or ammonia gas passage portion are formed in a housing, and which communicates with the ultrapure water passage portion. A raw water inlet and a distributor provided in an intermediate portion connecting them, a resistivity adjusting ultrapure water outlet communicating with the ultrapure water passage portion, and a confluence portion provided in the intermediate portion connecting them. A bypass flow path that connects the distribution unit and the confluence unit is provided, and the ultra pure water raw water that the distribution unit enters from the ultra pure water raw water inlet is supplied to the ultra pure water passage unit and the bypass flow path at a constant rate. Distributing at a flow rate ratio, the gas permeable membrane dissolves carbon dioxide gas or ammonia gas in the ultrapure water raw water passing through the ultrapure water passage to a concentration of 90% or more of the equilibrium concentration determined by the gas pressure and water temperature. Also has the ability to A device for adjusting the specific resistance of ultrapure water, further comprising carbon dioxide supplied for the purpose of discharging dissolved oxygen and dissolved nitrogen that diffuse back from the ultrapure water to the carbon dioxide gas or ammonia gas side through the membrane. A device for adjusting the resistivity of ultrapure water, comprising a discharge facility capable of adjusting the discharge amount of gas or ammonia gas. 2. In order to adjust the specific resistance of ultrapure water, carbon dioxide or ammonia gas is brought into contact with ultrapure water through a gas permeable membrane, and carbon dioxide or ammonia gas is supplied to the ultrapure water to obtain the desired value. An apparatus for producing ultrapure water having a specific resistance value, which has a specific resistance value of, such as carbon dioxide gas in ultrapure water having a presumably fluctuating flow rate as a membrane module provided with a gas permeable membrane. A membrane module having the ability to dissolve ammonia gas to a concentration of 90% or more of the equilibrium concentration determined by the gas pressure and the water temperature is provided, whereby the specific resistance is constant even if the flow rate of the ultrapure water supplied changes. It is equipped with a means to generate ultrapure water in which carbon dioxide gas or ammonia gas is dissolved so that the value becomes a value, and the dissolved oxygen and dissolved nitrogen that diffuse back from the ultrapure water to the carbon dioxide gas or ammonia gas side through the membrane are discharged. For the purpose of releasing, part of the supplied carbon dioxide gas or ammonia gas is leaked to the outside of the module to keep the concentration of carbon dioxide gas or ammonia gas constant. (Pure water) side is equipped with a distribution unit and a bypass flow path, and the ultra pure water raw water is distributed to the membrane module and the bypass flow path at a constant flow rate ratio. An ultrapure water resistivity adjusting device, comprising means for merging and uniformly mixing the ultrapure water of (1) and diluting the ultrapure water after mixing so as to have a final target resistivity value. 3. A hollow fiber membrane module comprising a hollow fiber membrane as a gas permeable membrane, for producing a relatively small flow rate of carbon dioxide or ammonia gas dissolved ultrapure water, and a relatively large flow rate of ultrapure water. A bypass line for passing raw water, a distributor for distributing raw water of ultrapure water at a constant flow rate ratio to the membrane module and the bypass line, carbon dioxide or ammonia gas generated ultrapure water and an ultrapure water passing through the bypass line. 3. The apparatus according to claim 2, which comprises a confluent mixing device that joins the pure water and the raw water to mix them uniformly, and a pressure regulating valve for keeping the pressure of carbon dioxide gas or ammonia gas supplied to the membrane module constant. 4. The hollow fiber membrane module is an internal perfusion type in which carbon dioxide gas or ammonia gas is supplied to the space between the outer side of the hollow fiber membrane and the housing, and ultrapure water flows inside the hollow fiber membrane. The apparatus according to claim 3, wherein a plurality of the incorporated hollow fiber membranes are arranged in the housing in a state of being converged. 5. The hollow fiber membrane module has a carbon dioxide gas permeation rate of 1 × 10 ⁻⁶ [cm ³ / cm ² · sec · cmHg] or more and 10 [cm ³ / cm ²
・ Sec ・ cmHg] or less or ammonia gas permeation rate is 1 × 1
^{0 -6 [cm 3 / cm 2} · sec · cmHg] or ^{10 [cm 3 / cm 2 ·} sec · cmHg]
The device according to any one of claims 3, 4 and 5, wherein the following hydrophobic gas permeable membrane is incorporated in a housing. 6. The hollow fiber membrane is poly-4 methylpentene-1.
With an inner diameter of 20 to 350 μm and an outer diameter of 50
The device according to claim 5, which has a diameter of about 1000 μm. 7. A step of distributing raw water of ultrapure water at a constant flow rate ratio to two streams, and a carbon dioxide pressure or an ammonia gas pressure and a water temperature supplied to one of the ultrapure water streams through a gas permeable membrane. A process of dissolving carbon dioxide gas or ammonia gas to a carbon dioxide gas concentration or ammonia gas concentration of 90% or more of the determined equilibrium concentration to generate ultrapure water having a specific resistance value adjusted. A function to leak a part of the supplied carbon dioxide gas or ammonia gas to the outside of the module for the purpose of discharging dissolved oxygen and dissolved nitrogen that diffuse back to the gas or ammonia gas side, and keep the carbon dioxide concentration or ammonia concentration constant. And a step of combining the carbon dioxide gas- or ammonia gas-dissolved ultrapure water and the other raw water of the ultrapure water with each other. 8. In the method for adjusting the resistivity of ultrapure water, in order to produce an amount of ultrapure water whose resistivity has been adjusted in accordance with the varying amount of consumption, the ultrapure water raw water supplied in accordance with the amount of consumption is The distribution device splits the flow into two streams having a relatively large flow rate at a constant flow rate ratio, and supplies one stream to the hollow fiber membrane module for flowing ultrapure water and carbon dioxide gas or ammonia gas across the membrane. A small flow rate of carbon dioxide or ammonia gas dissolved ultrapure water is generated within the range of the fluctuating flow rate that is assumed in advance, and at that time, the reverse diffusion from the ultrapure water to the carbon dioxide gas or ammonia gas side through the membrane is dissolved. For the purpose of discharging oxygen and dissolved nitrogen, a part of the supplied carbon dioxide gas or ammonia gas is leaked to the outside of the module to have a function of keeping the carbon dioxide gas concentration or ammonia concentration constant, and the carbon dioxide gas or ammonia gas is kept constant. The near-gas dissolved ultrapure water is made to have a carbon dioxide gas concentration or ammonia gas concentration of 90% or more of the equilibrium concentration determined by the carbon dioxide gas pressure or ammonia gas pressure and the water temperature at that time, and the carbon dioxide gas or ammonia gas-dissolved ultrapure water has a large flow rate. The raw water of the ultrapure water, which has been divided into, is mixed and uniformly mixed to obtain ultrapure water adjusted to a predetermined specific resistance value.
Method of adjusting the resistivity of ultrapure water. 9. The method according to claim 8, wherein the ratio of the flow rate of the low flow rate carbon dioxide or ammonia gas-dissolved ultrapure water to the high flow rate ultrapure water is less than 1/50. 10. In order to maintain the carbon dioxide concentration or ammonia gas concentration of carbon dioxide or ammonia gas-dissolved ultrapure water, the pressure regulating valve keeps the carbon dioxide gas pressure or ammonia gas pressure in contact with the hollow fiber membrane constant, and For the purpose of discharging dissolved oxygen and dissolved nitrogen that diffuse back from pure water to the carbon dioxide or ammonia gas side through the membrane, some of the supplied carbon dioxide or ammonia gas is leaked to the outside of the module to release carbon dioxide or ammonia. 10. The method according to claim 9, wherein the gas concentration is kept constant, and the supply amount of carbon dioxide gas or ammonia gas is relatively changed in accordance with the fluctuation of the flow rate of the ultrapure water that flows into the hollow fiber membrane module in a branched manner.