JP4570380B2 - Method for producing methanol - Google Patents

Description

The present invention relates to a manufacturing method of Rume ethanol used in the resist composition.

As one of microfabrication techniques employed when manufacturing information electronic devices such as semiconductors and LCDs, there is a lithography technique using a resist composition in which a resist resin is dissolved in a solvent. In lithography technology, a spin coating method is widely used as a method for applying a resist composition to a substrate.
As a solvent for the resist composition, a solvent having a low viscosity is selected, and a mixed solvent composed of several types of solvents is used depending on the type of resist resin and the working environment. In the mixed solvent, a high boiling point solvent, a medium boiling point solvent, and a low boiling point solvent are combined, and as the low boiling point solvent, methanol having high resin solubility is often used.
In recent years, it has been studied to use a mixed solution of methanol and water as an active material of a fuel cell.

By the way, when an ion component, a metal, and a particle are contained in the resist composition, corrosion called electrocorrosion may be caused to cause circuit disconnection or short circuit. In a fuel cell, if an active material contains an ionic component, metal, or particles, the life of the solid electrolyte or the catalyst electrode may be deteriorated. Therefore, as high purity as possible is required as methanol used in resist compositions and fuel cells. However, the actual situation is that the request is not fully satisfied.
Methanol is produced overseas and is transported to Japan by tankers. Methanol transported to Japan is temporarily stored in tanks and then supplied in pipelines, or supplied in tank lorries, drums, and oil cans. However, since methanol is easily oxidized by oxygen to formaldehyde and formic acid, there is a problem that the purity is lowered and ions and metals in contact with methanol are dissolved.
The present invention has been made in view of the above circumstances, ion components, metal, particles, such as formaldehyde and formic acid content of impurities less preferred Der Rume Tano Le for the use or fuel cells resist composition An object is to provide a manufacturing method.

Method of manufacturing methanol according to the present invention is not more than 30 cells / ml the number of particles greater than the particle diameter of 0.5 [mu] m, 100 pieces of the number of particles or particle size 0.3 [mu] m / ml or less, or more particle size 0.2μm particles A method for producing methanol having a number of 200 pieces / ml or less , comprising the step of filtering methanol through a filter at least twice and then passing it through an ion exchange membrane. The filter is rated as it goes downstream. It arrange | positions so that filtration accuracy may become small, and the rated filtration accuracy of the filter of the most downstream side shall be 0.2 micrometer or less .
In the method of manufacturing methanol according to the present invention, a filter to be used for final filtration is preferably one that is composed of a fluorine resin or polyethylene resin.

According to the method of manufacturing methanol according to the present invention, ionic components, particles, metals, amount of impurities, such as formaldehyde and formic acid can be reduced. Therefore, in the case of using methanol of the present invention obtained by the above production method in the resist composition can prevent the occurrence of disconnection and short circuit by suppressing galvanic corrosion. Further, when used in a fuel cell, it is possible to prevent the life deterioration of the solid electrolyte and the catalyst electrode. Therefore, the methanol in the present invention is suitable for resist compositions and fuel cells.

An exemplary embodiment of a main Tano Le production method of the present invention will be described with reference to FIG.
Figure 1 is a diagram schematically showing an apparatus for producing methanol for performing the method of manufacturing methanol according to the present exemplary embodiment. Manufacturing apparatus of this methanol 10 includes a first filter 11 for filtering the discharged methanol from the distillation column, the second filter 12 further filtering the filtered methanol through the first filter 11, a first It has an ion exchange membrane 13 for treating methanol filtered by the filter 11 and the second filter 12 and is schematically configured.

In the manufacturing apparatus 10 of this methanol, the first filter 11 is composed of polyethylene resin.
The second filter 12 is made of a polyethylene resin and has a lower rated filtration accuracy than the first filter 11. Here, the rated filtration accuracy is the particle diameter at which the filtration efficiency is 99.9% or more, and the filtration efficiency is (number of particles before filtration−number of particles after filtration / particles before filtration). It is a value obtained by (number) × 100 (%). In other words, the smaller the rated filtration accuracy, the finer the filter.
In the manufacturing apparatus 10 of the methanol, the ion exchange membrane 13 is to H-type ion exchange group is modified into a hole inside a polyethylene film.

Then, using the manufacturing apparatus 10 having such a methanol, performs a method of manufacturing methanol as follows.
First, the methanol immediately after distillation is passed through the first filter 11, and then the methanol that has passed through the first filter 11 is passed through the second filter 12 and filtered. Then, to obtain a final methanol through the methanol passing through the second filter 12 to the ion-exchange membrane 13. At this time, methanol, first filter 11, second filter 12, the continuous production of methanol through continuously in the ion-exchange membrane 13.
In the production method of this methanol, by filtration through a first filter 11 and second filter 12, for removing particles contained in the methanol. In the ion exchange membrane 13, metal ions are removed by exchanging metal ions contained in methanol and proton ions of ion exchange groups. Further, the particles are adsorbed on the anion of the ion exchange group and trap the particles in methanol. This adsorption is a phenomenon that occurs because particles are positively charged in methanol.

  In this production method, it is important to pass methanol through an ion exchange membrane after passing through a filter. That is, by removing most of the particles with the first filter 11 and the second filter 12 and passing through the ion exchange membrane 13, methanol having a small number of particles can be brought into contact with the ion exchange membrane 13. The life of the exchange membrane 13 can be extended. In addition, when methanol immediately after distillation is passed through the ion exchange membrane 13, methanol having a large number of particles comes into contact with the ion exchange membrane 13, and the ion exchange group is immediately blocked by the particles. Ion exchange ability is easily lost. Therefore, since the exchange frequency of the ion exchange membrane 13 increases, the cost increases. Further, when methanol is filtered only through the first filter and then passed through the ion exchange membrane, not only the particles cannot be sufficiently removed, but also the ion exchange ability of the ion exchange membrane tends to disappear.

Such methanol obtained in the following 30 cells / ml the number of particles greater than the particle diameter of 0.5 [mu] m, 100 pieces of the number of particles or particle size 0.3 [mu] m / ml or less, or more particle size 0.2μm The number of particles is 200 particles / ml or less. If the number of particles in methanol is in the above range, the amount of impurities is small enough to increase the quality and yield of the final product.
Here, the number of particles is a value measured at a flow rate of 100 ml / min using a particle counter (KL-22) manufactured by Lion Co., Ltd.

Further, methanol of this is because it is passed through the ion exchange membrane 13, a metal ion contained in methanol is also removed.
Specifically, the sodium content in the methanol is 10ppb or less, the potassium content 3ppb less calcium content is equal to or less than 10ppb. Thus, in methanol, since sodium, potassium, calcium content less, in the case of using methanol in the resist composition can be prevented electrolytic corrosion. Further, since the iron content in the methanol is equal to or less than 1 ppb, it can be prevented troubles caused by magnetic iron electronic components. Further, other metals are 1 ppb or less.
Here, the metal content in methanol is a value determined by ICP-MS absolute calibration curve method by adding nitric acid to methanol and then evaporating and then adding pure water to make a measurement sample.
Further, methanol obtained in the above production method, the content of formaldehyde and formic acid is small.

As described above, in the method of manufacturing methanol according to the present exemplary embodiment, on the by the first filter 11 and second filter 12 to remove particles in methanol, the particle by an ion exchange membrane 13, a metal ion, since the removal of formaldehyde and formic acid, ultimately resulting Rume ethanol has less amount of impurities.
Thus in the case of using the impurities of small Ime ethanol resist composition, it is possible to prevent occurrence of disconnection and short circuit by suppressing galvanic corrosion. Further, when used in a fuel cell, it is possible to prevent the life deterioration of the solid electrolyte and the catalyst electrode. Therefore, the methanol in the present invention is suitable for resist compositions and fuel cells.

Note that the present invention is not limited to the above-described embodiments. For example, in the embodiment described above, both the first filter 11 and the second filter 12 are made of polyethylene resin, but are not limited to polyethylene resin, and may be other resins. However, it is preferable that at least the second filter 12 is made of polyethylene resin or fluororesin. Those made of polyethylene resin or fluororesin have low solubility in methanol and are unlikely to generate new particles. Therefore, if the second filter 12 is made of these resins, the number of particles in methanol can be reduced. . The second filter 12 preferably has a rated filtration accuracy of 0.2 μm or less because the particle removal rate is further increased.
The material of the first filter 11 is not limited, but when it is desired to further reduce the number of particles, a material made of polyethylene resin or fluorine resin is preferable. Moreover, the 1st filter 11 may be the same as the filter used for filtration at the time of manufacturing normal purity methanol.
The ion exchange membrane 13 may be a membrane having at least an H-type ion exchange group. The ion exchange capacity of the ion exchange membrane 13 is preferably 15 milliequivalents or more because the removal rate of particles and metal ions is further increased.

  Filtration with a filter may be performed three times or more. When filtering three times or more, in order to reduce the number of particles, it is preferable that the filter used for the last filtration is comprised from a polyethylene resin or a fluororesin. Furthermore, it is preferable that the rated filtration accuracy decreases in order from the filter used for the first filtration to the filter used for the last filtration. Thus, if the rated filtration accuracy decreases in order, clogging of the filter can be prevented, and thus the filtration efficiency increases.

  In the above-described embodiment, methanol is continuously passed through the first filter 11, the second filter 12, and the ion exchange membrane 13. After passing methanol through the first filter, the inside is a polyethylene resin. Alternatively, it may be once accommodated in a sealable container coated with a fluororesin, supplied from the container, passed through the second filter, and then passed through the ion exchange membrane. However, if methanol is continuously passed through the first filter, the second filter, and the ion exchange membrane, the time from the filtration by the first filter to the filtration by the second filter can be shortened. Since formation can be suppressed, it is preferable.

Using the manufacturing apparatus of shown to methanol in Figure 1, it was produced methanol as follows.
First, the methanol immediately after distillation is passed through the first filter 11, and then the methanol that has passed through the first filter 11 is the second filter 12 “Penflon” (polytetrafluoroethylene resin) manufactured by Nippon Pole Co. Manufactured, rated filtration accuracy: 0.10 μm, filtration area: 1.1 m ² ). The second methanol passed through the filter 12 is an ion-exchange membrane 13 Nippon pole Co. Ltd. "Ion Clean" (ion exchange capacity: 16 milliequivalents or more) through successive obtain a final methanol It was.
The number of particles and a metal content of methanol of this was measured. Table 1 shows the measurement results of the number of particles, and Table 2 shows the measurement results of the metal content.

As shown in Table 1, the manufacturing methanol obtained by the method, 30 is the number of particles or particle size 0.5 [mu] m / ml or less, the number of particles greater than the particle diameter of 0.3μm or less 100 / ml, The number of particles having a particle diameter of 0.2 μm or more was 200 particles / ml or less, and there were few impurities.
Further, as shown in Table 2, the resulting methanol by the manufacturing method described above, in any of the metal, its content is equal to or less than 1 ppb, for example, sodium content, the potassium content, calcium content Was less than 0.1 ppb and the iron content was 0.4 ppb.

Methanol of the present invention, because the purity is very high, can be particularly preferably used in the resist composition and a fuel cell in the manufacture of sensitive electronic components impurities.

The manufacturing apparatus for performing the method of methanol in the embodiment according to the present invention is a diagram schematically showing.

Explanation of symbols

11 First filter (filter)
12 Second filter (filter)
13 Ion exchange membrane

Claims (2)

The number of particles having a particle diameter of 0.5 μm or more is 30 / ml or less, the number of particles having a particle diameter of 0.3 μm or more is 100 / ml or less, and the number of particles having a particle diameter of 0.2 μm or more is 200 / ml or less. A manufacturing method comprising:
Filtering the methanol at least twice through a filter and then passing through an ion exchange membrane ;
The filter, arranged so that the rated filtration precision toward the downstream side becomes smaller, features and be Rume ethanol manufacturing method of to the rated filtration precision of the most downstream filter to 0.2μm or less. Methanol The method of claim 1, wherein the filter used in the final filtration is those composed of fluororesin or polyethylene resin.

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