WO1999027003A1

WO1999027003A1 - Highly clean porous polyvinyl acetal resin, method for preparing the same, and method for storing the same

Info

Publication number: WO1999027003A1
Application number: PCT/JP1997/004249
Authority: WO
Inventors: Jun Inoue; Yasuoki Sasaki; Megumi Tanno
Original assignee: Aion Co., Ltd.
Priority date: 1997-11-21
Filing date: 1997-11-21
Publication date: 1999-06-03
Also published as: DE69735412D1; EP1035157B1; EP1035157A4; DE69735412T2; EP1035157A1; AU5066398A

Abstract

A porous polyvinyl acetal resin which has a cleanness of not more than 5 ppm in terms of COD, an electric conductivity of not more than 5 νS/cm, and a number of particles having a size of not more than 2.5 νm of 50,000 cc. The porous resin, when used in the step of cleaning within a clean room and other steps, can shorten or dispense with pretreatments required in the prior art, for example, a treatment for sufficiently pre-washing the porous resin for preventing the elution of impurities.

Description

TECHNICAL FIELD The present invention relates to a high-purity porous polyvinyl acetal resin, a method for producing the same, and a method for storing the same.

The present invention relates to a polyvinyl acetal resin porous material, and a method for producing and storing the same, which is free from contamination by organic substances, dissolved ions, and particulate matter.

Was also added in the process for producing the polyvinyl acetate resin porous body.

The porous material is free from contaminants and residues due to free substances of polyvinyl alcohol, which is an auxiliary material and a main material, and chemicals added for the purpose of sterilization and fungicide of the polyvinyl acetate resin porous material. It relates to a method for producing and storing a body in a wet state. Background art

BACKGROUND ART Porous polyvinyl acetal resin is well known as a material having excellent water absorbency and water retention and preferable softness and resilience when wet. Utilizing such properties, polyvinyl acetal resin porous materials are widely used as the most suitable material for cleaning tools, cleaning materials and the like. In particular, it has been used in many industrial applications because it is hydrophilic and has excellent cleaning ability, yet it is hard to damage the rubbing object and has excellent strength. It plays an important role in cleaning applications in clean rooms, cleaning for semiconductors and electronic components, and as a member for water absorption.

Here, the polyvinyl acetal resin porous body is also called a polyvinyl acetal sponge, and is hereinafter abbreviated as “PV At sponge”.

As described above, PVA t sponge is a powerful material that is the best material for cleaning applications in clean rooms, etc.PVA t sponge hardens when dried, and has the property of losing its flexibility and elasticity. To be effective, it is generally necessary to use it in a wet state. In addition, the water absorption rate of the PVAt porous material has a large difference between the dry state and the wet state, and the water absorption rate in the dry state is significantly higher than that in the wet state. It is slow. In addition, it is troublesome to transfer a dry state to a wet state, and it is practically preferable to always keep the wet state so as not to dry.

〇

However, there is a problem that a PVAt-based porous body is liable to generate mold when stored in a wet state for a long time. The occurrence of mold is problematic in terms of hygiene, appearance, and handling, and it is necessary to impart fungicidal properties to the PVAt-based porous body.

A problem in the storage method of such PVAt sponge is contamination of the porous body by organic substances, ionic substances, fine particles, microorganisms, and the like. Must be reduced to the limit. On the other hand, as a conventional method of preserving a PVAt sponge, a method of impregnating and adhering a product having a fungicidal and bactericidal property to a product is generally performed. For example, aqueous solutions of sodium dehydroacetate, 4,1-methyl 3,5-dimethylphenol, benzalkonium chloride, and benzimidazole are used.

However, if the PVA t sponge treated and stored with an aqueous solution containing chemicals is used in this state for cleaning semiconductors, etc., these chemicals will be mixed into the ultrapure water, which is the cleaning water, and washed. Water and cleaning objects are contaminated. Therefore, in order to remove these agents from the PVAt sponge which has been treated and stored with an aqueous solution containing the agent, the PVAt sponge is subjected to a long-term pre-cleaning before use.

In addition, when the PVAt sponge is treated with a drug and stored, there is also a problem that the porous body is deteriorated and deteriorated due to the effect of the drug depending on the type of the drug used.

In particular, when PVA t sponge is used in applications such as semiconductor-related cleaning materials ゃ electronic-related water absorbing materials, for example, precision cleaning of silicon wafers, photomasks, cleaning of printed circuit boards, lead frames, etc. When used for water absorption, contaminants eluted from the PVA t sponge not only degrade the quality of the product, but also contaminate the production system and the environment itself, causing serious damage. Thus, when used in a clean room or in a highly clean and controlled environment, It is required to extremely reduce contaminants generated from the porous body, and the storage method using the above-mentioned chemicals has not been able to satisfy these requirements.

To address these issues, autoclave sterilization by heating and pressurizing, sterilization using oxidizing gas such as ethylene oxide and ozone, and placing the product in a closed container and using an inert gas for the gas inside. Substitution methods, sterilization by ultraviolet rays, etc. can be mentioned, and materials other than PVA t sponge are appropriately selected from these methods and used. However, none of them is effective against PVAt sponge. For example, in autoclave sterilization, the material itself shrinks due to heat treatment, and the flexible elasticity which is a characteristic property of PVAt sponge is lost. Further, in sterilization using an oxidizing gas, it is difficult to make the gas penetrate deep into the porous body, and the material itself is susceptible to deterioration due to oxidation. Even with a method of replacing with an inert gas in a closed container, it is not easy to remove water adhering to the porous body and oxygen dissolved in the material itself, and it is possible to completely prevent the generation of mold. Absent. In the method using ultraviolet rays, ultraviolet rays only act on the surface layer of the porous body, and it has been difficult to commercialize the method.

The present inventor has conducted intensive studies in view of the above-mentioned circumstances. It has been found that there is no generation of dust and it is possible to shorten or omit the pre-cleaning before use, and an object of the present invention is to provide a high cleanness PVA t sponge and a method for producing the same, and a high cleanliness. An object of the present invention is to provide a storage method that can maintain the purity of a PVA t sponge with high accuracy and that is very easy to handle. Disclosure of the invention

The present invention relates to a high-purity PVA t sponge and a high-purity PVA t sponge that is washed with pure water from which impurities such as particles, ions, and organic substances dissolved and suspended in water are removed. The method is characterized in that the whole of the high-purity PVA t sponge thus manufactured is hermetically sealed with an oxygen-blocking film, and the oxygen absorbent is contained in the sealed bag. Things. The high cleanliness PVA t sponge of the present invention has a COD value as cleanliness of 5 pm or less, and further has a conductivity of 5 S / cm or less, and a particle number of 2.5 m or less particles of 5 m or less. It is characterized in that the number is not more than 0000 / cc.

The use of the high-cleanliness sponge of the present invention shortens the pre-treatment that was conventionally required, such as pre-cleaning sufficiently to prevent impurities from being eluted, when used in the cleaning process in a clean room. Or it can be omitted. Furthermore, higher cleanliness enables use under harsh environmental conditions such as semiconductor manufacturing processes.

In the method for producing a high cleanliness PVA t sponge, the PVA t sponge is washed with pure water from which impurities such as particles, ions, and organic substances dissolved or suspended in water are removed. The conductivity of pure water used for the method is 0.1 / LL Scm or less and the COD value is 1 ppm or less. Further, it is more preferable that the cleaning with pure water is performed in an environment in which the degree of cleanliness is higher than the class 100 defined by the US Federal Standard FS209D. A high purity PV At sponge can be manufactured. Furthermore, by increasing the cleanliness of pure water used in the production, it is possible to produce a high-purity PVAt sponge that can be used even under severe environmental conditions such as a semiconductor production process.

In addition, by increasing the cleanliness of the environment to be cleaned, it is possible to produce a high-purity PV At sponge that can be used even when more stringent quality conditions are required.

In addition, in the preservation method of high cleanliness PVA t sponge, PVA t sponge manufactured with high cleanliness is hermetically packaged with an oxygen barrier film, and an oxygen absorbent is built into the sealed packaging bag. It is characterized by doing.

According to the storage method of the present invention, the high cleanliness PV At sponge is stored together with an oxygen absorbent in a sealed package having an oxygen barrier property so that the inside of the sealed package is in an oxygen-free state or an oxygen-free state. By maintaining a low oxygen concentration close to that, it is not necessary to use a fungicide, and it is possible to maintain the cleanliness of the PVA t sponge with high accuracy. In addition, the time for pre-processing can be shortened or omitted even during use.

Further, the oxygen barrier film has an oxygen permeability of 200 cc / m ² · atm · 24 hr or less. By using such a material having excellent oxygen barrier properties, it is possible to create a state having a low oxygen concentration, which is almost anoxic.

It is more preferable to incorporate an oxygen detecting agent in the hermetically sealed package. According to such a packaging method, the presence of oxygen in the package can be detected if the package is partially torn or loses hermeticity, and a defective product is used by mistake. Can be prevented beforehand.

In addition, in the method of preserving a high-purity PVA t sponge, as a method of increasing cleanliness, a high-purity PVA t sponge is hermetically packaged, and then irradiated with an electron beam or an a-ray. . In this way, it is not necessary to use an antifungal agent, and the cleanliness of the PVAt sponge can be maintained with high precision. In addition, since the PVA t sponge is sterilized by electron beam or a-beam irradiation, mold is less likely to be generated even in the presence of oxygen. Therefore, the packaging for preservation only needs to be hermetically sealed. Further, it is possible to provide a method of preserving a high-purity PVA t sponge which can be used by simply performing pretreatment at the time of use. Here, when the irradiation dose of the electron beam or the X-ray irradiation is set to lO k Gy or less, the change in the physical properties of the sponge can be extremely suppressed. When the irradiation dose increases, for example, the compressive stress increases, that is, the sponge becomes hard.

Further, when performing electron beam or a-beam irradiation, it is preferable to reduce the oxygen concentration in the sealed package. This is because irradiation with an electron beam or an α-ray activates oxygen, and the activated oxygen may deteriorate the sponge. Therefore, airtight packaging with an oxygen barrier film is used, and an oxygen absorbent is incorporated in the airtight packaging. Furthermore, the oxygen permeability of the oxygen barrier film should be 200 cc / m ² · atm • 24 hr or less. Is preferred. By doing so, the oxygen concentration in the sealed package can be kept extremely low, and the change in the physical properties of the sponge can be further reduced. Can be .

Further, when the package is hermetically sealed, it is preferable to cover the sheet with a sheet molding in advance. In this way, the oxygen absorbent can prevent the high-purity PVAt sponge from being deformed even if the inside of the package is under reduced pressure. In addition, deformation due to external pressure can be prevented.

It is more preferable that the hermetically sealed package is further covered with a film material and sealed, and then double-wrapped. In this way, if only the exterior is discarded at the time of use, contamination of the use environment can be further reduced.

It is more preferable to perform hermetically sealed packaging in an environment in which the degree of cleanliness specified by US Federal Standard FS209D is higher than Class 100. By packaging in such an environment, high cleanliness that can be used even under severe environmental conditions can be maintained.

In addition, as described above, PVA t sponge is often used for cleaning in clean rooms, cleaning for semiconductors and electronic components, and as a water absorption member. It is useful to apply the high-cleanliness PV At sponge of the present invention and its manufacturing method and storage method to a certain cleaning sponge roller.

To explain the present invention in more detail, pure water used in the method of the present invention has a conductivity at 25 ° C of 0.1 S./cm or less, a total organic carbon content of 1 ppm or less, and 0.3 Z It is preferable that the water quality is such that the number of particles is 100 or less per ml and the number of viable bacteria is 10 or less Zm1, and the conductivity at 25 ° C is 0.055 / ml. It is preferable to have water quality such that i SZcm or less, total organic carbon content is 1 PPm or less, one or more particles of 0.1 or more are 1 Zm1 or less, and the number of bacteria is 0.01 or less / m1. By washing the PV At sponge using such water-quality ultrapure water, foreign substances adhering to the porous body are removed with high precision. Ultrapure water of such quality can be applied to general filtration, microfiltration membrane, ultrafiltration membrane, reverse osmosis membrane, dialysis membrane, ion exchange, etc., and can also be obtained by any combination of these. Things.

The cleanliness of the PVA t sponge obtained by washing using the ultrapure water described above is such that the conductivity is 5 S.cm or less, the COD value is 5 ppm or less, and the sodium ion (Na + ) Concentration is less than 1 ppm, and the number of particles less than 2.5 // m is less than 50000 Zcc. This value is applicable to the semiconductor manufacturing process.

The values of conductivity and sodium ion (Na +) concentration are the values of sponge-adhered water itself. The COD value is a value obtained by rubbing a PVA t sponge in pure water and then measuring the pure water.

Details of each measurement value and measurement method will be described later.

As the oxygen-barrier film used in the present invention, polyvinylidene chloride, nylon, polyvinyl acetate, polyvinyl alcohol, aluminum foil, and aluminum-deposited film can be suitably used, and more preferably, oxygen permeability is 10%. cc / m ² · atm · ²

Those having a temperature of 4 hrs (20 to 25 ° C) or less are good. Further, a film obtained by laminating several kinds of films having high oxygen barrier properties or a film obtained by combining a film of polyethylene, polyester, polypropylene or the like with the above-described oxygen barrier film is more preferable in terms of strength.

As the exterior for performing double packaging, an oxygen-blocking film may be used as in the interior, but an oxygen-permeable film may also be used. For example, polyethylene, polypropylene, polyester, General-purpose materials such as nylon can be used. The purpose of this exterior is to remove the exterior bag when transporting the PVA t sponge out of the clean room and carrying it back into the clean room if double wrapped even if the surface of the wrapper is contaminated. Just by peeping can remove the contamination and clean room can be prevented from being contaminated.

In addition, as the oxygen absorbent incorporated in the above-mentioned wrapper made of a material having high oxygen barrier properties, a substance which is easily oxidized chemically can be used. For example, ascorbic acid, active metal powder, sulfite and the like can be used. Although it can be used, an iron-based material is preferable in consideration of handleability, oxygen absorption speed, oxygen absorption capacity, and the like.

Further, the oxygen absorbent is more effective when it is a fine powder because it has higher reactivity with oxygen, but it is necessary to prevent the oxygen absorbent from coming into direct contact with the porous material to be stored. In general, the fine powder is used by sealing the fine powder with a material having pores finer than the particle system of the oxygen absorbent fine powder and having air permeability.

According to the storage method described above, the PVA t sponge in the package is washed immediately with pure water. Cleanliness for a long time

Methods for easily removing oxygen gas from the package include vacuum packaging and a method of degassing the gas inside the package and replacing it with an inert gas such as nitrogen or argon. It is more preferable to use this method together with the method because it is difficult to completely remove the oxygen generated.- In addition, in order to confirm the presence or absence of oxygen in the packaging, a reversible colorant that changes its color depending on the oxygen concentration is used. It is also effective to incorporate it in a wrapper as an oxygen detector. As a result, the oxygen concentration in the wrapper can be easily confirmed, so that more reliable product storage can be achieved.

Further, by irradiating the PVA t sponge which is hermetically packaged with an electron beam, the PVA t sponge is sterilized, and even if some oxygen is present, the generation of mold can be prevented. As a result, the package only needs to be able to be sealed and does not need to be an oxygen barrier film. Therefore, packaging and packaging operations can be simplified.

According to the method of the present invention, first, the PVA t sponge formed by the reaction between PVA and formalin was sufficiently washed with general water to remove reaction residues, unreacted materials, additives, and the like. After that, the above-described process of immersing in pure water having the above-described water quality to mechanically bend and stretch the sponge, sufficiently squeezing out the water contained in the sponge, and absorbing the pure water again is repeated.

Next, while the PVAt sponge after the washing is kept wet with pure water, the whole is covered with an oxygen-blocking film and completely sealed. At this time, enclose the oxygen absorbent and incorporate it together with the PVAt sponge. At this time, an oxygen detecting agent may be incorporated at the same time, or the whole PVAt sponge may be covered with a sheet molded body, and then the whole may be covered and sealed with an oxygen barrier film.

When oxygen in the wrapper is absorbed by the oxygen absorbent, the inside of the wrapper is decompressed, and the built-in PVA t sponge product is deformed, and the deformed part is not restored, for example, when this deformation is maintained for a long time. However, this problem can be avoided by covering the entire PVAt sponge with a relatively hard sheet molding or the like. Furthermore, if the PVA t sponge wrapped with the oxygen barrier film is further covered and wrapped with a film body and double-wrapped, if the outer body is discarded only when using the PVA t sponge, contamination of the usage environment will be reduced. It can be further reduced.

In consideration of reverse contamination of the PVA t sponge from those contained in the wrapper together with the PVA t sponge, such as the oxygen absorber and oxygen detector described above, these members should be positioned so that they do not come into direct contact with the PVA t sponge. More preferably, for example, it is also possible to provide a structure for fixing these members to a part of the sheet molded body.

HE.

Further, the method according to the present invention is applicable not only to storage of a porous material that cures in a dry state, but also to storage of a material composed of other polymers. For example, for rubber-based materials such as NBR and SBR, and for fibrous materials such as non-woven fabrics, to prevent deterioration due to oxidation of the materials themselves, and to maintain the performance of chemicals added to them It can also be used for the purpose.

As described above, according to the present invention, by washing and storing the PVA t sponge, there is no contamination by fine particles, organic substances, ions, etc., and further, no contamination or residue by the antifungal agent. The porous body can be stored in a wet state for a long time.

Further, according to the method of the present invention, the conventional pre-cleaning can be shortened or omitted when using the PV At sponge.

In addition, since the PVAt sponge can be maintained in an oxygen-free state for a long period of time, not only the antifungal effect but also the deterioration of the porous material itself due to oxidation can be prevented. Furthermore, it can be widely used not only for porous materials and those in a wet state, but also for members that need to prevent deterioration and deterioration due to oxidation. ―

The inspection method for each measurement item indicating cleanliness will be described below. (C O D, unit: p p m)

Object to be measured: Sponge 100 cc in distilled water 400 cc, rubbed out 100 times, and adjusted to a total of 500 cc with tap water.

Measurement method: Coulometric titration method: The amount of potassium permanganate when an organic substance in a liquid is oxidized with a permanganate reactor is expressed in terms of equivalent oxygen. Measuring equipment: Portable and quick type COD meter (HC-507) manufactured by Central Science Co., Ltd. +

(Conductivity, unit: SZc m)

Measurement object: Sponge squeezed liquid after standing for about 3 minutes with DI water sufficiently contained in the sponge

Measurement method: AC two-electrode method; put the electrode in the liquid and measure the electric conductivity.

Measuring equipment: Compact conductivity meter (B-173 type) manufactured by HORIBA, Ltd. (number of particles, unit: 1,000 / cc)

Object to be measured: Water sponge 100 cc was rubbed out 100 cc in tap water 100 times and adjusted to a total of 100 cc with tap water.

Measurement method: Light-blocking particle counter; Measures the size of each particle with a diameter of 2.5 zm or more in 10 cc of the liquid to be measured based on the voltage drop due to blocking of the halogen light. Count the quantity.

Measuring equipment: H I AC / ROYCO (MOD E L 4 i 00)

(Na ion concentration, unit: ppm)

Measuring method: sodium ion electrode method; Drop sample liquid on flat sensor.

Measuring equipment: Compact ion meter (CANDY C-122), manufactured by HORIBA, Ltd. Brief description of drawings

FIG. 1 is an explanatory diagram of a storage method according to the present invention, and FIG. 2 is an explanatory diagram showing a structure of an oxygen-barrier film used for hermetic packaging.

FIG. 3 is an explanatory view of a sponge nozzle in Example 1, and FIG. 4 is an explanatory view of a state of cleaning with a brush roller in FIG. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

(Example 1)

A sponge roller 1 made of polyvinyl acetal (PVA t) (size: outer diameter 60 mm x inner diameter 30 mm x length 25 4 ran) was converted to a COD value of 1 ppm and an electrical conductivity at 25 ° C of 0. 0 6 / SZcm, 2.5 or more particles 0 water / m 1 After immersion in pure water with water quality and mechanically bending and stretching in water, moisture contained in the sponge After squeezing out the washing water, the same operation was repeated with fresh pure water to wash the PV At sponge nozzle. Next, after the washing, the sponge roller in a wet state is stored in a package 2 (size: 45 Ommx 170 sq.) Made of an oxygen-blocking film as shown in FIG. Inject agent 3 and oxygen detector 4 and heat seal the opening to completely seal.

As shown in Fig. 2, the oxygen-blocking film used had a four-layer structure. The outer layer consists of polyvinylidene chloride 5, nylon 6, polyethylene 7, and linear low-density polyethylene 8, each of which has a thickness of 5〃, 10〃, 25〃, and 60〃. there were. Mitsubishi Gas Chemical Company (Ageless FX-400) was used as the oxygen absorbent, and Mitsubishi Gas Chemical Company (Ageless Eye KS) was also used as the oxygen detector.

The sponge roller 11 is used for precision cleaning of an aluminum disk or the like, and has a large number of protrusions 9 on the surface as shown in FIG. Then, as shown in FIG. 4, the rotation of the sponge roller 11 causes the protrusion 9 to wash the object 10 such as an aluminum disk while rubbing it in the presence of water or the like.

(Example 2)

As in Example 1, the PVA t sponge nozzle was cleaned. Next, after this washing, the sponge nozzle in a wet state is stored in a polyethylene film package (size: 45 Omm x 17 Omm), and the oxygen absorbent and the oxygen detector are not put in. Heat seal the opening and seal completely. Thereafter, the entire package was irradiated with an electron beam. The irradiation energy was 5 MeV and the irradiation dose was 4 kGy.

(Comparative Example 1) A sponge nozzle made of PVA t (size: outer diameter 60 mm x inner diameter 30 mm x length 254 mm) was wetted with pure water as described above, but was not washed. This is stored in an oxygen-blocking film wrapper (size: 450 x 170), and the opening is heated and sealed with only the oxygen detector without the oxygen absorber. And sealed. The same oxygen barrier film as in Example 1 was used.

(Comparative Example 2)

The sponge roller (outer diameter 6 Ommx inner diameter 3 Ommx length 25.4 sq.) Made of PVAt was only wet with pure water as described above, but no washing was performed. This was housed in a wrapping bag (size: 450 mm x 170 mm) made of a polyethylene film, and an oxygen absorbent and an oxygen detector were charged, and the opening was heat-sealed and completely sealed. The same oxygen absorber and oxygen detector as in Example 1 were used.

(Comparative Example 3)

A sponge roller made of PVA t (size: outer diameter 60 o'clock X inner diameter 3 Ommx length 2 5 4 2 ΐ) was added to sodium dehydroacetate 0.3 wt% aqueous solution 3, OOO cc, and oxalic acid 0.3 A 1% by weight aqueous solution was immersed in a mixed solution of 3,000,000 cc to make the water content the same as in Example 1. Next, this was stored in a wrapping bag made of polyethylene film (same as in Comparative Example 2), and only the oxygen detector was enclosed without an oxygen absorber and completely sealed. The same oxygen detector as in Example 1 was used.

(Comparative Example 4)

The sponge roller (size: outer diameter 60 x inner diameter 3 Omm x length 2 5 4 mm) consisting of PV At is simply wetted with the pure water described above, but not washed. This was stored in an oxygen-blocking film wrapper (size: 45 Omm x 170 concealed), the air inside the wrapper was vacuum-vacuumed, and nitrogen gas was introduced. An intellectual agent was added and completely sealed. The same oxygen barrier film as in Example 1 was used.

(Comparative Example 5)

A sponge roller composed of PVAt (size: outer diameter 6 Ommx inner diameter 3 Ommx length 25.4 mm) was washed in the same manner as in Example 1. Next, after this washing, the sponge nozzle in a wet state is placed in a polyethylene film package (size: 450 mm X 1). 70), and at the same time, introduce an oxygen absorbent and an oxygen detector, heat and seal the opening, and completely seal it. The same polyethylene film as in Comparative Example 2 was used

(Comparative Example 6)

A sponge roller made of PV At (size: outer diameter 6 O mm x inner diameter 3 O mm x length 2 5.4 hidden) was washed in the same manner as in Example 1. Next, after this washing, the sponge roller in a wet state is stored in a polyethylene film package (size: 450 mm x 17 O mm), and only the oxygen detector is added without the oxygen absorber. The opening was heated to close and completely sealed. The same polyethylene film as in Comparative Example 2 was used.

Each of the PVA t sponge rollers treated as described above was placed in a constant temperature room kept constant at 23 ° C, and the appearance change was observed over time. After storage for 200 days, the oxygen-blocking wrapper is opened, the PVAt sponge roller is removed, immersed in pure water for pre-cleaning, and the cleanliness of the sponge roller is measured at each cleaning time. did. The appearance of the porous roller 1, that is, the state of mold generation, was as shown in Table 1 below.

Presence of mold USAlso; US n π S S 1 u u <J ϋ ο ο tl 丄 0 Η ^ Ο Α Α Α Α りホ I

^ .m \ 丄

Shirashi

Ratio ¾ίExample 1 + +10

Ratio L + tens + + Q

Comparative Example 4t + 10 Comparative Example 5 + Comparative Example 6 + + + No mold found

More than one mold colony was found

+ + 3 or more mold colonies found

More than 10 mold colonies were observed In Example 1 of the sponge roller made of the PVAt sponge of the present invention and the method for producing and storing the sponge, as shown in Table 1, the generation of fungi could be prevented for at least 200 days.

Also in Example 2, by irradiating the packed sponge nozzle with an electron beam, the generation of mold was prevented for at least 200 days as in Example 1. This is because the sponge roller is sterilized by electron beam irradiation, and even if some oxygen is present, the generation of mold can be prevented. As a result, the package only needs to be sealable, and does not need to be an oxygen barrier film. Also, packaging and packaging operations can be simplified.

Comparative Example 3 in Table 1 is a conventional method in which a conventional antifungal agent is added. No mold is generated, but the object of the present invention cannot be achieved.

On the other hand, the other comparative examples are methods in which the fungicide is not added, and Comparative Examples 1, 2 and 4 are not washed with pure water. In Comparative Example 1, since the oxygen absorbent was not contained, molds were generated by the oxygen remaining in the package. In Comparative Example 2, since the packaging film does not have oxygen barrier properties, if the amount of oxygen permeation exceeds the capacity of the oxygen absorbent, mold will be generated. In Comparative Example 4, since the air in the package was first replaced with nitrogen gas and packaged with an oxygen barrier film, the generation of mold was slower than in Comparative Examples 1 and 2. Since no absorbent is added, oxygen gradually penetrates into the package, generating mold.

Further, Comparative Examples 5 and 6 are examples in which cleaning with pure water was performed. In both cases, a polyethylene film was used without using an oxygen blocking film. In Comparative Example 5, an oxygen absorbent was added, and the results were good in Comparative Examples, but not as good as in Examples. In Comparative Example 6, no oxygen absorber was added, and the result was worse than Comparative Example 5.

As described above, in order to keep the PVA t sponge free of mold and to store it in a wet state, the inside of the packaging for storage must be in an oxygen-free state or a state with a low oxygen concentration close to the oxygen-free state. For this purpose, as in the present invention, it is necessary to seal the PVA t sponge together with an oxygen absorbent with an oxygen-blocking film. As described above, according to the embodiment, when the PVA t sponge is stored in a wet state, the PV At sponge is washed with pure water and then stored in an oxygen-free state or a state having a low oxygen concentration close to the oxygen-free state. By storing, the generation of mold can be suppressed for a long time.

Next, the cleanliness of the roller was measured for each cleaning time. As a method of measuring the cleanliness of the roller at each cleaning time, the PVA t sponge roller was cut and collected by an amount equivalent to 50 m1, and this was subjected to a COD value of lp pm and an electrical conductivity of 0 at 25 ° C. 0 6 SZcm, 2.5 // immersed in 500 ml of pure water with a water quality of 0 particles / m 1 or more, and given compression and release and bending in water 100 times Later, the pure water was analyzed. The results are as shown in Table 2.

Thus, in the examples, the eluted components are within the usable range with a short pre-washing time. However, in Comparative Examples 1, 2, and 4, a long pre-cleaning time was required because cleaning with pure water was not performed. Furthermore, in Comparative Example 3, since the fungicide was eluted, the conductivity was high.

In Comparative Examples 5 and 6, cleaning with pure water was performed, and the results were the same as in Example 2.

Conductivity (S / cm

Pre-cleaning time

Mamoru 1 J no 0 1 9 3 4

0.5 0. 1 0. 06 0. 06 0. 06 Ι \ 1 5. 0 1. 0 0. 5 0. 1 0. 1

5.0 1.0 0 0.5 0 0.1 0 Comparative example 3 4 0 0 5 0 2 0 5 1 Comparative example 4 5.0 1. 0 0.5 0 0.1 0 0.1

Furthermore, the results of confirming the presence or absence of oxygen in the wrapper with the oxygen detector incorporated are shown in Table 3. In Table 3, the state in which the oxygen concentration reached 0.1% or less was indicated as “absent”.

Table 3 Presence or absence of oxygen in the package Elapsed days 10 days 30 days 60 days 100 days 200 days Example 1 Example 2 Yes Yes Yes Yes Yes Comparative Example 1 Yes Yes Yes Yes Yes Comparative Example 2 Yes Yes Yes Yes Comparative example 3 Yes Yes Yes Yes Yes Comparative example 4 Yes Yes Yes Comparative example 5 Yes Yes Yes Yes Comparative example 6 Yes Yes Yes Yes Yes Thus, in Example 1, the inside of the package is kept free of oxygen for a long time. On the other hand, in the comparative example, there is an example in which the oxygen concentration can be kept low in a short time, but cannot be maintained for a long time.

As described above, according to Example 1, when the polyvinyl acetal sponge is stored in a wet state, it is stored in an oxygen-free state or in a state having a low oxygen concentration close to the oxygen-free state, so that the mold is generated for a long time. Can be suppressed.

Further, according to the present invention, since the porous body can be maintained in an oxygen-free state for a long time, not only the antifungal effect but also the deterioration of the porous material itself due to oxidation can be prevented. Furthermore, it can be widely used for storing not only porous materials and those in a wet state, but also members that need to prevent deterioration and deterioration due to oxidation.

In Example 2, the sponge was sterilized by electron beam irradiation. Therefore, even in an environment where oxygen was present, the mold could be prevented from being produced if the package was hermetically sealed. Industrial applicability

The preservation method of the present invention is a method in which the eluate and dust from the PVA t sponge are extremely reduced, and the pretreatment such as washing can be shortened or omitted at the time of use. Even when stored, it has an antifungal effect for a long period of time and retains the porous body in an oxygen-free state, so that there is no deterioration or deterioration due to oxidation, and it is extremely useful in practical use.

Claims

The scope of the claims

1. A high-purity polyvinyl acetal resin porous material characterized by a COD value of 5 ppm or less as cleanliness.

2. Conductivity as cleanliness is 5 SZcm or less, COD value is 5 ppm or less, and 2.5 // m or less particles are 500 000 particles / cc or less. High-purity polyvinyl acetal resin porous material.

3. A method for producing a porous polyvinyl acetal resin having high cleanliness, characterized by washing with pure water from which contaminants such as particles, ions, and organic substances dissolved or suspended in water have been removed.

4. The method for producing a high-purity polyvinyl acetal resin porous material according to claim 3, wherein the conductivity of pure water used for washing is 0.1 SZ cm or less and the COD value is 1 ppm or less. .

5. The cleaning method according to claim 3 or 4, wherein the cleaning with pure water is performed in an environment in which the cleanliness is maintained higher than class 100 specified in US Federal Standard FS209D. PROCESS FOR PRODUCING POROUS POLYVINYL ACetal RESIN

6. A method for storing a high-purity polyvinyl acetal resin porous body, characterized in that a polyvinyl acetal resin porous body produced with high cleanliness is hermetically packaged with an oxygen-blocking film.

7. The method for preserving a high-purity polyvinyl acetal resin porous body according to claim 6, wherein an oxygen absorbent is incorporated in a hermetically sealed package made of an oxygen-barrier film.

8. The high-purity polyvinyl acetal resin porous material according to claim 6 or 7, wherein the oxygen barrier film has an oxygen permeability of 200 cc / m 2 · atm · 24 hr or less. How to save the body.

9. The method for storing a high-purity polyvinyl acetal resin porous body according to any one of claims 6 to 8, wherein an oxygen detecting agent is incorporated in the hermetically sealed package.

10. A method for preserving a high-purity polyvinyl acetal resin porous body, which comprises sealingly packaging a polyvinyl acetal resin porous body produced with a high degree of cleanliness, and then irradiating an electron beam or an α-ray. .

11. The method for preserving a porous polyvinyl acetal resin having high cleanliness according to claim 10, wherein the irradiation dose of electron beam or alpha beam irradiation is 1 OkGy or less.

12. The high-purity polyvinyl acetal according to claim 10 or 11, characterized in that the hermetic packaging is hermetically sealed with an oxygen-barrier film, and an oxygen absorbent is contained in the hermetically sealed packaging. Method for preserving resin porous body.

13. The method for storing a highly clean polyvinyl acetal resin porous material according to claim 12, wherein the oxygen permeability of the oxygen-barrier film is 200 cc / m ² · atm · 24 hr or less. .

14. A claim characterized in that the hermetic packaging is performed in an environment where the cleanliness is maintained at a level higher than Class 100 as the cleanliness specified by US Federal Standard FS209D. Item 14. The method for storing a high-purity polyvinyl acetal resin porous material according to any one of Items 6 to 13.

15. The hermetically sealed polyvinyl acetal resin porous body produced at a high degree of cleanliness, wherein the porous polyvinyl acetal resin body is preliminarily coated with a sheet molded body when the hermetically sealed polyvinyl acetal resin porous body is packaged. Item 6. The method for storing a highly clean porous polyvinyl acetal resin according to any one of Items 6 to 14.

16. The high-purity polyvinyl acetate according to any one of claims 6 to 15, wherein the hermetically sealed package is further covered and sealed with a film material and double-wrapped. Method for preserving resin porous body.

17. The high-purity polyvinyl acetal resin porous body according to claim 1 or 2, wherein the porous polyvinyl acetal resin body is a cleaning sponge roller.

18. The method for producing a high-purity polyvinyl acetal resin porous body according to any one of claims 3 to 5, wherein the polyvinyl acetal resin porous body is a cleaning sponge roller.

19. The preservation of a high-purity polyvinyl acetal resin porous body according to any one of claims 6 to 16, wherein the polyvinyl acetal resin porous body is a cleaning sponge roller. Method.

9 Claims in the certificate

[1 January 30, 998 (30.01.98) Accepted by the International Bureau: Claim 2 originally filed has been amended; other claims remain unchanged. (Page 3)] '

1. Porous high-purity polyvinyl acetal resin characterized by a COD value of 5 ppm or less as the cleanliness.

2. (After correction) When the conductivity as cleanliness is 5 SZ cm or less, and the COD value is 5 ppm or less, and the number of particles with a value of 5 / zm or more is 500 000 or less Zc c A high-purity polyvinyl acetal resin porous body characterized in that:

4. The method according to claim 3, wherein the conductivity of pure water used for washing is 0.1 SZcm or less and the COD value is 1 ppm or less.

5. The cleaning method according to claim 3 or 4, wherein the cleaning with pure water is performed in an environment in which the cleanliness is maintained higher than class 100 specified in US Federal Standard FS209D. CLEANING PROCESS FOR PRODUCING POROUS ACID POLYMER RESIN

6. A method for storing a high-purity polyvinyl acetal resin porous body, characterized in that a porous polyvinyl acetal resin body manufactured with high cleanliness is hermetically packaged with an oxygen-blocking film.

8. The oxygen permeability of the oxygen barrier properties films ^{2 0 0 c cZm 2 * a} tm '2 4 hr range paragraph 6 of hereinafter is a claim or high cleanliness polyvinyl § Se tar porous resin according to paragraph 7 How to save the body.

23 Amended paper (Article 19 of the Convention)

10. Preservation of high-purity polyvinyl acetal resin porous material characterized by tightly packaging and then irradiating electron beam or y-ray on the polyvinyl acetal resin porous material manufactured with high cleanliness. Method.

11. The method for preserving a high-purity polyvinyl acetal resin porous body according to claim 10, wherein the irradiation dose of electron beam or a-beam irradiation is 10 kGy or less.

12. The high-purity polybutylacetal according to claim 10 or 11, wherein the package is hermetically packaged with an oxygen-barrier film, and an oxygen absorbent is contained in the package. Method for preserving resin porous body.

13. The method for preserving a high-purity polyvinyl acetal resin porous material according to claim 12, wherein the oxygen permeability of the oxygen-barrier film is 200 cc / m ² · atm · 24 hr or less. .

15. When the polyvinyl acetal resin porous body manufactured with high cleanliness is hermetically packaged, the polyvinyl acetal resin porous body is previously coated with a sheet molded body. Item 6. The method for storing a highly clean porous polyvinyl acetal resin according to any one of Items 6 to 14.

16. The high-cleanliness polyvinyl acetal resin porous material according to any one of claims 6 to 15, wherein the hermetically sealed package is further covered and sealed with a film material and double-wrapped. How to save the body.

18. The method for producing a highly clean porous polyvinyl acetal resin according to any one of claims 3 to 5, wherein the porous polyvinyl acetal resin is a cleaning sponge roller. .

24 Amended paper (Article 19 of the Convention)

25 Amended paper (Article 19 of the Convention)