KR20140016717A - Pma recycling method - Google Patents

Abstract

The present invention provides a PMA regenerating method for reproducing propylene glycol monomethylether acetate (PMA) used in a photoresist process. The PMA regenerating method according to an embodiment of the present invention contains the PMA and impurities and comprises: a step of preparing organic solvent used in the photoresist process; and a step of converting the impurities into organic compounds with different boiling points by adding 2-ethylhexanol and/or amine compounds in the organic solvents.

Description

PMA recycling method {PMA recycling method}

The present invention relates to a method for purifying organic solvents for regenerating PMA, and more specifically, to reproducing propylene glycol monomethylether acetate (PMA, hereinafter referred to as 'PMA') used in the photoresist process. It relates to a PMA regeneration method for.

BACKGROUND ART [0002] Lithography is widely used to manufacture electronic circuits, pixels, and the like in a manufacturing process of a display such as a semiconductor and a TFT-LCD. This lithography is a method used to create a fine pattern on a substrate, a process of transferring the circuit pattern of the mask to the substrate by irradiating light through a mask on which a desired pattern is printed on the photoresist, the photoresist is applied The photoresist is generally composed of a binder component resins, photoinitiators, various pigments, dispersants and other additives.

When the lithography process using the photoresist is carried out, a photoresist is applied to an undesired portion, that is, a portion such as a photoresist applying nozzle, a coating peripheral equipment, or an edge of the substrate in the photoresist applying process. It may cause defects in the photoresist coating process and must be removed. At this time, organic solvents are used to remove unwanted photoresist. Therefore, the organic solvent after removing the photoresist includes components of the photoresist, that is, resins, photoinitiators, pigments, and additives, as impurities.

In some cases, organic solvents contaminated with impurities may be incinerated, but in addition, harmful chemicals are generated during the incineration process, and the use value of the organic solvent itself decreases, and thus, recently used organic solvents may be reused in the display manufacturing process. Regeneration treatment with a high purity organic solvent is performed.

Regeneration of such an organic solvent is usually separated using fractional distillation using the difference in boiling point for each component similarly to the general purification method of the organic solvent. However, there are many other organic solvent impurities included in the organic solvent having similar boiling points to the organic solvent to be recovered. These similar boiling point impurities are not easy to be separated by distillation of the organic solvent component to be recovered and require a very high number of distillation towers.

 In particular, methyl 3-methoxypropionate (MMP) and cyclohexanone (Cyclohexanone), which are present as impurities in the organic solvent, are substances to be finally purified from the organic solvent, as shown in Table 1 below. The boiling point was similar to that of PMA, so separation and removal were almost impossible. In addition, the problem was more serious when the organic solvent content of methoxypropionate and cyclohexanone is high.

PMA MMP Cyclohexanone Boiling point (℃) 146 143 155.65

Therefore, in order to solve the above problem,

The problem to be solved by the present invention is to provide a method for reproducing high purity, high quality PMA even in the presence of a large amount of methyl 3-methoxypropionate and cyclohexanone which cannot be removed by fractional distillation alone in an organic solvent based on PMA. It is.

The problem to be solved by the present invention is not limited to the above-mentioned technical problem, other technical problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, the present invention adds 2-ethylhexanol (2-Ethyl-1-hexanol) and an amine compound to the organic solvent mixture containing propylene glycol monomethyl ether acetate (PMA) and impurities It provides a PMA regeneration method comprising the step of reacting the impurities having a similar boiling point to PMA into organic compounds having different boiling points.

In the PMA regeneration method of the present invention, the impurities preferably include at least one or more of methyl 3-methoxypropionate and cyclohexanone.

According to the PMA regeneration method of the present invention, by converting impurities having a boiling point similar to that of propylene glycol monomethyl ether acetate to a substance having a different boiling point, separation by distillation or the like is facilitated, and a high-purity organic solvent can be regenerated in high yield. do.

Fig. 1 shows the result of gas chromatography analysis according to Example 1. Fig.

Hereinafter, the present invention will be described more specifically.

The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used in a sense that can be commonly understood by those skilled in the art. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

Hereinafter, a PMA regeneration method according to an embodiment of the present invention will be described.

One embodiment of the present invention is a PMA regeneration method for regenerating propylene glycol monomethylether acetate (PMA, hereinafter referred to as 'PMA') contained in the organic solvent used in the photoresist process, PMA regeneration method according to an embodiment of the step of preparing an organic solvent used in the photoresist process containing PMA and impurities, and 2-ethylhexanol (2-Ethyl-1-hexanol) is added to the organic solvent To convert impurities into other organic compounds. Each step will be described in more detail below.

First, the steps of preparing an organic solvent are as follows.

The photoresist process is a process involved when forming a circuit or the like in a semiconductor process or when forming a color filter in a TFT-LCD process. After a pattern such as a circuit or a pattern of a color filter is formed in the photoresist process, the photoresist in a portion where the photoresponsive reaction does not occur must be removed. It is also common to remove the photoresist for pattern formation located on the pattern to produce the final product.

In order to remove the photoresist, an organic solvent is used. On the other hand, the organic solvent used in the photoresist removal process is not discarded as it is, but is recovered and managed by an organic solvent and treated. This is because the components contained in the organic solvent contain chemicals that have fatal toxicity that can cause environmental pollution.

Such organic solvents may include PMA and impurities.

The impurities may be, for example, methyl 3-methoxypropionate (hereinafter referred to as 'MMP') cyclohexanone, other monomers, polymers, photopolymerization initiators, crosslinking agents or slurries. Can be.

In this case, the organic solvent may include, for example, about 75 to 85% PMA, 3 to 7% MMP, 1 to 3% cyclohexanone and other monomers, polymers, photopolymerization initiators, crosslinking agents, or slurries. have.

Among them, the PMA contained in the organic solvent can be regenerated and reused in another photoresist process. Thus, the manufacturing cost of a process for manufacturing a semiconductor or the like can be saved.

However, in the organic solvent, the substances listed above exist in the form of a mixture, which must be fractionally purified. Among them, the boiling point of PMA is 146, the boiling point of MMP is 143, and the boiling point of cyclohexanone is 155.65, so it is difficult to purify these substances by fractional distillation using boiling point. This is a cause of lowering the recovery rate of PMA.

Accordingly, in order to improve the recovery of PMA, MMP or cyclohexanone can be converted into an organic compound having a boiling point significantly different from that of PMA, thereby improving the recovery of PMA.

First, 2-ethylhexanol is added to an organic solvent. 2-ethylhexanol converts MMP contained in the organic solvent into 2-ethyl-1-hexyl-3-methoxypropionate having a high boiling point (hereinafter, referred to as 2-Ethyl-1-hexul-3-methoxypropionate). The reaction for converting the MMP into 2-ethyl-1-hexyl-3-methoxypropionate is called MMP conversion reaction.)

Hereinafter, an organic compound having a higher boiling point than PMA produced by adding 2-ethylhexanol to the organic solvent is referred to as a first organic compound. The first organic compound includes 2-ethyl-1-hexyl-3-methoxypropionate.

2-ethylhexanol may be used in an amount of 2.5 to 12.5 wt% based on the total weight of the organic solvent. Subsequently, MMP is decomposed as shown in the following formula (1).

A catalyst can be used to improve the rate of the MMP conversion reaction. At this time, preferably a titanium tetraisopropoxide catalyst may be used. Titanium tetraisopropoxide may be used in an amount of 1 to 7% by weight based on the total weight.

At this time, the boiling point of 2-ethyl-1-hexyl-3-methoxypropionate is 127 at 12 mmHg. Considering that the boiling point of PMA is 146 at atmospheric pressure (760 mmHg), the MMP conversion reaction converts MMP to 2-ethyl-1-hexyl-3-methoxypropionate having a boiling point higher than that of PMA. do.

By the MMP conversion reaction described above, MMP can be effectively converted to 2-ethyl-1-hexyl-3-methoxypropionate having a higher boiling point than PMA.

Next, an amine compound is added to the organic solvent converted from MMP to convert the cyclohexanone.

First, an amine compound is added to an organic solvent. Here, the amine compound may be, for example, a hydroxylamine, a hydroxylamine sulfate, or a hydroxylamine hydrochloride.

For example, hydroxylamine, hydroxylamine sulfate, or hydroxylamine hydrochloride are added to the organic solvent, and the hydroxylamine, hydroxylamine sulfate, or hydroxylamine hydrochloride and cyclohexanone are mixed at a temperature of 50 to 120 at 0.5. The reaction is carried out for 2 hours. As a result, cyclohexanone is converted to cyclohexanone oxime as shown in the following formula (2). (Hereinafter, the reaction for converting the cyclohexanone into cyclohexanone oxime is referred to as cyclohexanone conversion reaction.)

Hereinafter, a substance having a higher boiling point than PMA generated by adding the amine compound to an organic solvent is referred to as a second organic compound.

The second organic compound includes cyclohexanone oxime.

On the other hand, if the cyclohexanone conversion reaction is carried out at less than 50, the reaction may be very slow, or the reaction itself of the production of cyclohexanone oxime may not occur. When the cyclohexanone conversion reaction is performed in excess of 120, monomers, slurries and the like contained in the organic solvent may be mixed and distilled, thereby reducing the efficiency of the purification process.

On the other hand, if the cyclohexanone conversion reaction proceeds in less than 0.5 hours, cyclohexanone may not be sufficiently changed to cyclohexanone oxime. In addition, when the cyclohexanone conversion reaction proceeds for more than 2 hours, the change to the cyclohexanone oxime may be sufficiently made, but it may be difficult to expect the change to the cyclone hexanon oxime any longer.

On the other hand, after the reaction, the organic solvent may include a salt, in order to remove this may be added to the diethanolamine (Diethanolamine). Thereby, the purity of the PMA can be further increased.

Cyclohexanone oxime, on the other hand, has a higher boiling point than conventional cyclohexanone. The boiling point of cyclonehexanone oxime is 206 to 210 at atmospheric pressure (760 mmHg). That is, it has a boiling point higher than 146 which is the boiling point at normal pressure of PMA.

Next, in the organic solvent in which the MMP and the cyclohexanone are converted to 2-ethyl-1-hexyl-3-methoxypropionate and cyclohexanone oxime through the aforementioned MMP conversion reaction and cyclohexanone conversion reaction. Purifying the PMA through fractional distillation is carried out.

More specifically, the organic solvent including 2-ethyl-1-hexyl-3-methoxypropionate and cyclohexanone oxime at atmospheric pressure is fractionally distilled in a temperature atmosphere of 130 to 150. Thereby, PMA having a boiling point lower than that of 2-ethyl-1-hexyl-3-methoxypropionate and cyclonehexanone oxime will be distilled and 2-ethyl-1 having a boiling point higher than the temperature range Hexyl-3-methoxypropionate and cyclohexanone oxime will remain. That is, PMA distilled at the top of the reactor on which the organic solvent is supported can be obtained.

When the organic solvent is heated in the above temperature range, the boiling point is lower than 2-ethyl-1-hexyl-3-methoxypropionate (127 at a boiling point of 12 mmHg) and cyclohexanone oxime (206 to 210 at a boiling point of 760 mmHg). PMA (146 at boiling point 760 mmHg) will phase change into the gas phase and distill to the top of the reactor.

Thereafter, the obtained gaseous PMA can be cooled to 146 or less to obtain a liquid PMA. On the other hand, gas phase PMA or liquid phase PMa is passed through a filter to remove the slurry contained in the PMA obtained in the gas phase or liquid phase. Here, a membrane membrane filter made of Teflon may be used as the filter medium.

Example -One

The gas chromatography (Gas Chromatography, hereinafter 'G / C') analysis of the organic solvent used in the photoresist process is shown in FIG. 1. As can be seen in FIG. 1, it can be seen that the organic solvent contains MMP and cyclohexanone (denoted as 'Anone' in FIG. 1), which are impurities, and other impurities are also included. . Representatively, propylene glycol monomethyl ether (PGME) is also included in the organic solvent.

Example -2

In 200 g of an organic solvent whose main component is PMA containing 5% PMA as the main impurity and about 1% of cyclohexanone, 2-ethylhexane was used to convert MMP into 2-ethyl-1-hexyl-3-methoxypropionate. 18.4 ml of nal and 8.8 ml of titanium tetraisopropoxide are added and the reaction is carried out at reflux for 1 hour. At this time, the reaction process is checked by G / C to find the end point of which the content of 2-ethyl-1-hexyl-3-methoxypropionate is 0.5% or less.

Subsequently, 2.5 g of hydroxylamine sulfate and 3.5 ml of diethanolamine were added to react cyclohexanone to cyclohexanone oxime, followed by reaction at 100 to 120 for 2 hours.

Example -3

The organic solvent of Example 2 was fractionally distilled under a atmospheric pressure of 145 to 150 at atmospheric pressure. At this time, about 160g of PMA of 99.5% purity is obtained.

According to the PMA regeneration method according to the present invention, a pigment nozzle attached to a trichromatic pigment spray nozzle when a color filter is manufactured to realize a color screen in which a color filter and a TFT array substrate (TFT-Array Substrate) are main components. 2-ethylhexanol was added to the organic solvent used for cleaning and removal of the photoresist applied to the color filter and discharged as waste. After the reaction, the amine compound was added and reacted with the organic solvent. PMA of the above purity) can be purified.

In addition, when the present invention is applied to the production, it is possible to achieve a production yield improvement and a breakthrough throughput improvement compared to the conventional production method. According to the present invention, unnecessary organic solvent components contained in the waste PMA generated in the color filter manufacturing process can be removed and reused in the color filter manufacturing process to be reused at the waste solution generating place, thereby achieving improvement of environmental problems and cost reduction .

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (9)

PMA regeneration method for reproducing propylene glycol monomethylether acetate (PMA, hereinafter referred to as 'PMA') used in the photoresist process,
Preparing an organic solvent including the PMA and impurities and used in the photoresist process; And
And adding 2-ethylhexanol to the organic solvent to react with the impurities, thereby converting the impurities into a first organic compound having a higher boiling point than PMA. The method according to claim 1,
Titanium tetraisopropoxide is used as a catalyst in the step of converting the impurities into the first organic compound having a higher boiling point than PMA. The method according to claim 1,
Wherein said impurity comprises methyl 3-methoxypropionate. The method of claim 1,
Wherein said first organic compound is 2-ethyl-1-hexyl-3-methoxypropionate. The method according to claim 1,
And adding an amine compound to the organic solvent to convert the impurities into a second organic compound having a higher boiling point than PMA. 6. The method of claim 5,
Said amine compound is hydroxylamine, hydroxylamine sulfate or hydroxylamine hydrochloride. The method of claim 6,
Wherein said impurity comprises cyclohexanone. The method of claim 7, wherein
Wherein said second organic compound comprises cyclohexanone oxime. 6. The method of claim 5,
And fractionally distilling the organic solvent to obtain the PMA.

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