KR101199963B1 - Method for purifying waste of aqueous rework chemical for lcd panel and reusing the purified rework chemical - Google Patents

Abstract

The present invention relates to a method for purifying and regenerating waste liquids of aqueous rework chemicals used to remove color filter photoresist and thermally cured overcoat of defective panels generated during TFT-LCD manufacturing. . Purification and regeneration method of the present invention comprises the steps of centrifuging the waste liquid; Sludgeating the resin and depositing an inorganic alkali by vacuum distillation; Removing the sludged resin and the precipitated inorganic alkali. According to the purification and regeneration method of the present invention, the reprocessing chemical can be recycled with high efficiency and the reprocessing chemical regeneration solution with the same composition of the new liquid can be produced while minimizing the use of raw materials, thereby reducing the manufacturing cost and wastewater treatment amount. have.

Description

METHOD FOR PURIFYING WASTE OF AQUEOUS REWORK CHEMICAL FOR LCD PANEL AND REUSING THE PURIFIED REWORK CHEMICAL}

The present invention provides a method for purifying waste liquids of rework chemicals, especially water based reprocessing chemicals, which are used to remove color filter photoresist and thermally cured overcoat of defective panels generated during TFT-LCD manufacturing. It is about how to play.

As the size of TFT-LCD substrates is enlarged to more than 8 generations, the amount of various solvents directly or indirectly involved in the manufacturing process is rapidly increasing. Therefore, there is an urgent need for process technology to reduce the manufacturing cost of TFT-LCD through efficient use of solvent. In order to reduce the consumption of solvents, each manufacturing company is trying to reduce the amount of solvents used per substrate by improving the process technology such as focusing on the development of compositions to extend the service life or applying them using highly efficient raw materials. Performance is still marginal. Rework chemicals that remove photoresist in solvents include organic alkali-based reprocessing chemicals, such as tetramethylammonium hydroxide (TMAH), potassium hydroxide (KOH), and hydroxides. There are aqueous reprocessing chemicals based on inorganic alkalis such as sodium hydroxide (NaOH). However, TMAH has a low removal efficiency for thermosetting overcoat, and inorganic alkali water reprocessing chemicals are mainly used.

In general, TFT-LCD is manufactured by combining color filter panel and TFT panel. Especially, color filter panel has a color filter formed with resin black matrix, red (R), green (G), and blue (B) pixels and to protect them. An overcoat is formed therein, and a column spacer is formed in the middle to keep the cell gap constant at the bonding of the color filter panel and the TFT panel. Finally, a TFT-LCD is completed by forming an alignment layer thereon, injecting liquid crystal by ODF (One drop Filling) method, and then bonding the liquid crystal. In this case, the color filter panel may be defective when subjected to various processes, and the expensive ledger glass panel may be reused through a rapid stripping process by reprocessing chemicals.

Reprocessing chemicals are almost impossible to separate from chemical components since they are in the form of compositions that dissolve black matrices, color filters R, G, B photoresists, thermoset overcoats, column spacers, and the like formed on the panel. Therefore, only the recycling of the components through fractional distillation using different boiling points of the components used, the reprocessing chemicals are not purified and a considerable amount of waste is disposed of. Therefore, if it is determined that the current reprocessing chemical has reached the end of its life for the company, it is generally discharged by consignment or self-treatment. In addition, the reprocessed chemicals (hereinafter referred to as "waste liquids") that are disposed of contain a large amount of toxic substances such as amines and organic solvents, and thus, a huge treatment cost is required to remove them during the wastewater treatment process. Hazardous acids are added, which adds a lot of time, manpower and facility costs, making them environmentally and economically undesirable.

Therefore, purifying and reusing waste liquids is a highly desirable approach in terms of efficient reuse of solvents, reducing treatment costs, and even environmental aspects. However, until now, technology development related to reprocessing chemicals has been proceeding mainly to improve performance, and technology for refining and recycling waste liquids of reprocessing chemicals due to difficulty in separating components has not made much progress.

Korean Patent Application No. 10-2004-0028767 discloses a method for separating and recovering TFT-LCD mixed acid waste etching solution with high purity. Although it is composed of the step of recovering mixed acid to ultra high purity through the process of melting molten film and the process of vacuum evaporation under reduced pressure, the purity of acid increases the risk of handling and the stability of the device requires economical efficiency and efficiency.

Korean Patent Application No. 10-2006-0031098 discloses a stripper reuse method of a photoresist. In particular, this technology is used to continuously install the filter configuration in parallel to remove the debris, but there is a disadvantage that it is difficult to apply universally to all chemical processes used to obtain the metal pattern of the TFT panel.

Korean Patent Application No. 10-2007-0113338 discloses a chemical liquid recovery device that can easily recover the waste liquid by operating the circulation pump smoothly even if this substance is contained in the chemical or bubbles are generated inside the recovery pipe.

Korean Patent Application No. 10-2009-0011048 discloses a chemical recycling method using a supercritical fluid. Particularly, a stripping solution (ie, a stripper used in TFT panel manufacturing) that removes a resist pattern as a method of reacting a chemical containing foreign matter with a supercritical fluid to precipitate foreign matter and regenerating the filtrate through a filtration process, Although it can be used for thinners to remove unnecessary resists, cleaning agents used in various cleaning processes, etc., there is a disadvantage that it is possible only within a limited area.

In addition to this, there are various refining techniques and refining apparatuses for various waste liquids, but there is still a lack of a method for effectively regenerating reprocessing chemicals, and many kinds of reprocessing chemicals are still disposed of.

It is an object of the present invention to provide an effective purification and regeneration method capable of regenerating a high proportion of waste liquid from reprocessing chemicals.

In particular, the present invention aims to provide a simpler, more economical and more efficient purification and regeneration method through physical separation, rather than chemical component separation, for aqueous reprocessing chemicals.

In order to solve the above problems, the present invention provides a method for purifying and regenerating an aqueous reprocessing chemical waste liquid for treating a defective LCD panel comprising the following steps:

(a) centrifuging the waste liquid of the aqueous reprocessing chemical comprising 5-30 wt% of dimethyl sulfoxide, 5-20 wt% of an inorganic alkali hydroxide and 15-30 wt% of a water-soluble amine compound;

(b) removing water by vacuum distillation with respect to the centrifuged supernatant to sludge the dissolved resin and to precipitate inorganic alkali;

(c) removing the sludged resin and the precipitated inorganic alkali.

As used herein, unless otherwise defined, the term "waste liquid" refers to a reprocessing chemical that is disposed of and deemed to have expired.

According to one preferred embodiment of the present invention, the purification and regeneration method of the present invention further comprises a filtration step of passing the centrifuged supernatant of step (a) through a membrane filter having a pore size of 0.1 to 10 μm. Can be. In addition, the step (a) may further include the step of passing the supernatant through a mesh filter after immersing the waste liquid prior to centrifugation.

In addition, according to a preferred embodiment of the present invention, the step of removing the resin and the inorganic alkali includes removing by centrifugation or filtration.

According to a preferred embodiment of the present invention, the centrifugation is performed at a rotation speed of 1,000 to 15,000 rpm for 0.5 to 3 hours, and more preferably for 1 to 2 hours at a rotation speed of 4,000 to 8,000 rpm.

According to a preferred embodiment of the present invention, the method may further include analyzing and correcting the components of the liquid from which the sludged resin and the precipitated inorganic alkali are removed. Analysis and calibration include analyzing the components of the filtrate by quantitative and qualitative analyzers and calibrating by a calibration program. The analyzer may in particular include an acid-base titrator, gas chromatography and moisture analyzer.

According to the present invention, it is possible to regenerate the water-based reprocessing chemical with high efficiency, and refill the reprocessing chemicals with the same composition as the new liquid composition while minimizing the use of raw materials by replenishing only part of the raw material shortage through correction by accurate qualitative / quantitative analysis. It can be manufactured to reduce the manufacturing cost and wastewater treatment amount.

1 is a process flow diagram illustrating a method for purifying and regenerating a reprocessing chemical waste liquid according to an embodiment of the present invention.
Figure 2 is a photograph of the upper layer, the lower layer and the used waste liquid separated after centrifugation, a filter process, distillation under reduced pressure, and the reprocessing chemical waste liquid in Example 5 of the present invention.

Aqueous reprocessing chemicals remove resin black matrices, color filters R, G, and B photoresists, thermoset overcoats, and column spacers formed on LCD panels, so that the waste liquid contains impurities that consist of pigments, cured resins, and small amounts of other additives. It will contain. In general, some of the impurities are dissolved in an aqueous reprocessing chemical, and after a certain time, the water is evaporated, the water content decreases, and the saturated and dissolved resins are first sludged and precipitated, followed by inorganic alkali. Proceeds. In addition, due to the decrease in solubility with temperature, impurities that have been saturated at high temperatures increase in the amount of precipitates formed when the temperature is lowered. Since the solubility of inorganic alkali in saturation is higher than the solubility of resin, most resins are sludged and easy to remove, and a certain portion of inorganic alkali is dissolved in saturated state and then precipitates as supersaturated.

The present invention focuses on these characteristics of the aqueous reprocessing chemical waste liquor to purify and regenerate the waste liquor through physical methods, that is, centrifugation, vacuum distillation, and filtration. Reprocessing chemicals that can exhibit high regeneration rates by this physical method applied in the present invention should be aqueous. In particular, the composition of the reprocessing chemical itself should be suitable for this method in order to be able to exhibit a regeneration rate of 80 to 90% or more. In the present invention, 5 to 30% by weight of dimethyl sulfoxide (DMSO) and inorganic alkali hydroxide The purification method of the present invention is applied to an aqueous reprocessing chemical comprising 5 to 20% by weight of the side and 15 to 30% by weight of the water-soluble amine compound.

In one preferred embodiment of the invention, the aqueous reprocessing chemical is 5-30% by weight of dimethyl sulfoxide (DMSO); Inorganic alkali hydroxide 5-20 wt%; Water soluble amine compound 15-30 wt%; 1 to 10 wt% of a protic glycol-based organic solvent; 1 to 10% by weight of an aprotic glycol-based organic solvent; And residual amount of water. Inorganic alkali hydroxides include sodium carbonate; Potassium carbonate; Sodium silicate; Potassium silicate; Sodium hydroxide; Potassium hydroxide or the like may be used alone or in combination of two or more thereof. Examples of the water-soluble amine compound include hydroxylamine, diethylhydroxylamine, monoethanolamine, diethanolamine, triethanolamine, 2- (2-aminoethoxy) ethanol, N, N-dimethylethylamine, N, N-diethylethanolamine, N, N-dibutylethanolamine, N-methylethanolamine, N-ethylethanolamine, N-butylethanolamine, N-methyldiethanolamine, monoisopropanolamine, triisopropanol Alkanol amines such as amines; Diethylenetriamine, triethylenetetraamine, propylenediamine, propylenediamine, N, N-diethylethylenediamine, N, N'-diethylethylenediamine, 1,4-butanediamine, N-ethyl-ethylenediamine, 1 , 2-propanediamine, 1,3-propanediamine, polyalkylenepolyamines of 1,6-hexanediamide, 2-ethyl-hexylamine, dioctylamine, tributylamine, tripropylamine, heptylamine, cyclo Aliphatic amines such as hexylamine; Aromatic amines such as benzylamine and diphenylamine; Cyclic amines, such as piperadine, N-methyl piperadine, and hydroxyethyl piperadine, may be used alone or in combination of two or more thereof. As a proton glycol organic solvent, For example, Ethylene glycol; Ethylene glycol monomethyl ether; Ethylene glycol monoethyl ether; Ethylene glycol monopropyl ether; Ethylene glycol monobutyl ether; Diethylene glycol; Diethylene glycol monomethyl ether; Diethylene glycol monoethyl ether; Diethylene glycol monopropyl ether; Diethylene glycol monobutyl ether; Triethylene glycol monomethyl ether; Triethylene glycol monoethyl ether; Triethylene glycol monopropyl ether; Quantum glycol organic solvents such as triethylene glycol monobutyl ether and derivatives thereof may be used alone or in combination of two or more thereof. As an aprotic glycol-type organic solvent, For example, Ethylene dimethyl ether; Ethylene diethyl ether; Ethylenedipropyl ether; Ethylene dibutyl ether; Diethylene glycol dimethyl ether; Diethylene glycol diethyl ether; Diethylene glycol dipropyl ether; Diethylene glycol dibutyl ether; Diethylene glycol methyl ethyl ether; Diethylene glycol methyl propyl ether; Diethylene glycol methyl butyl ether; Diethylene glycol ethyl propyl ether; Diethylene glycol ethyl butyl ether; Diethylene glycol propyl butyl ether; Triethylene glycol methyl ethyl ether; Triethylene glycol methyl propyl ether; Triethylene glycol methyl butyl ether; Triethylene glycol ethyl propyl ether; Triethylene glycol ethyl butyl ether; An aprotic organic solvent such as triethylene glycol propyl butyl ether and derivatives thereof may be used alone or in combination of two or more thereof.

1 is a process flow diagram illustrating a method for purifying or regenerating a reprocessing chemical waste liquid according to an embodiment of the present invention. Hereinafter, with reference to the accompanying drawings will be described in detail for each step of the purification and regeneration of the reprocessing chemical waste liquid according to the present invention.

Step 1: Immersion  And centrifugation

Typical compositions of reprocessing chemicals consist of inorganic alkalis, organic amines, organic solvents and water. Poor coating of LCD filter color filter photoresist and thermosetting overcoat. Used for reprocessing of the panel. The waste liquid of the reprocessing chemical at the end of its life is transferred to the waste storage (immersion tank) (flow 11). And when it cools, it isolate | separates into a supernatant liquid and a lower layer liquid. Natural sedimentation and cooling allow the primary separation of parts that can be easily removed. The precipitates and debris in the lower layer are transferred to the consigned waste storage tank, and the supernatant is introduced into the centrifuge (31) using a metering pump through a basic mesh filter (flow 12) to allow the resin and precipitates to be suspended in the supernatant. Remove alkali The sludge in the lower layer in the centrifuge 31 is transferred to the consigned waste storage tank, and the wastewater is treated with the precipitates and residues of the reprocessed chemical waste liquid, and the supernatant generated per hour is transferred to the first storage tank (flow 13). This separation of the supernatant / substrate removes as much of the impurities as possible to hinder the process flow to facilitate the purification and regeneration of subsequent reprocessing chemical waste.

The performance of the centrifuge 31 is expressed in RPM (rate per minute) or G (gravity acceleration), which is expressed in RPM on the pilot scale and in G in the large centrifuge. Centrifugation is a rotational speed of 1,000 ~ 15,000 rpm, preferably a rotational speed of 2,000 ~ 10,000rpm, more preferably 4,000 ~ 8,000rpm, operating time is performed for 0.5 to 3 hours, preferably 1 to 2 hours It is preferable. If the centrifugation speed and time is too low, the separation effect is insufficient, and if too high, the separation efficiency is improved, but in terms of efficiency, unnecessary work and economical. In the waste liquid reservoir, the upper and lower layers are preferably separated and discharged automatically. In particular, the separation and discharge of the supernatant from the centrifuge is automatically performed, and the separation efficiency of the supernatant is maximized compared to the separation method using a conventional fixed centrifuge or a decanter according to the automatic setting of temperature and time.

Second step: filter process

In the first storage tank separated and stored by centrifugation, a membrane filter with a pore size of 0.1 ~ 10㎛ is installed to remove impurities of fine size that are insufficient to remove in centrifugation, and to remove materials It is a method to increase the removal efficiency.

Step 3: vacuum distillation and cooling

The filtrate passed through the second step is distilled under reduced pressure to remove a certain amount of water (33, flow 15). In this case, when the water is evaporated by distillation under elevated temperature, a small amount of resin dissolved in the supernatant is sludged and inorganic. Alkali precipitates. After cooling to room temperature, most of the resin is removed to minimize and eliminate the content of impurities. After this process, it is the process of removing impurities again through centrifuge and filter process or filter process if necessary (flow 16, flow 13, flow 14).

Step 4: Analyze and Calibrate the Filtrate

The filtrate obtained through the two purification processes is subjected to quantitative and qualitative analysis using various analysis equipment (flows 17 and 34). Input by the manufacturing program for the weight and composition of the filtrate is automatically controlled by the manufacturing system, resulting in the addition of scarce raw materials (flow 18, flow 19). The regenerated liquid produced through this series of regeneration processes is used again for the reprocessing process (flow 20).

The analyzer is analyzed by using analytical and measuring instruments such as acid-base titrator, gas chromatograph, liquid chromatograph, IR, NMR, ICP / mass, moisture measurement analyzer, viscometer, density meter, etc. After determining the physical characteristics of the filtrate in advance, it is determined whether to regenerate it. In particular, near-infrared measurements may be used for multicomponent analysis.

Hereinafter, an Example is given and this invention is demonstrated in detail. However, it is to be understood that these embodiments may be embodied in various forms rather than limit the invention. In addition, the examples are provided so that this disclosure will be thorough and will fully convey the scope of the invention to those skilled in the art.

[Examples and Comparative Examples]

Example 1

Dimethyl sulfoxide 15w / w%, 45% calcium hydroxide 35w / w%, monoethanolamine 19w / w%, butyldiglycol 5w / w%, butyltriglycol 3w / w%, dimethyldiglycol 2w / w% and water 21w Reprocessing chemical was prepared at / w% (Example 8 of Korean Patent No. 10-0842853). Experimental method was reprocessed the panel while maintaining the 60 ℃ by using the ultrasonic method of 28kHz, 800W intensity by the spray method and the oscillation method using the nozzle. The LCD panel used was a panel size of 100 x 100 mm coated with a black matrix, color filter, overcoat and column spacer. Waste liquid from the reprocessing chemical was secured at the time of precipitation.

After the waste liquid of the reprocessing chemical is immersed in the waste liquid storage tank (sedimentation tank), the sediment is transferred to the consigned waste liquid storage tank for disposal, and the supernatant is centrifuged at 5,000 rpm using a centrifuge (Hanil Simed / DHCSM-250). Centrifuged for 1 hour. The precipitate was transferred to a consigned waste liquid storage tank for disposal, and the supernatant was filtered by passing through a microfilter resin (porous pine product of Chisosa / PTFE membrane type) having a pore size of 0.1 μm. The filtrate filtered by the filter process was distilled in a vacuum distillation (Buchi Thin Film Evaporator / 10mmHg, 60 ℃) to remove some water and then cooled to room temperature. The distillate was centrifuged at 5,000 rpm for 1 hour and filtered again with a 0.1 μm resin filter. The filtrate was stored in a regeneration solution reservoir, sampled in a regeneration solution reservoir, gas chromatography (Agilent, 7890A), moisture content meter (Metrohm, 831 KF Titrino Plus equipped with an additional 860 KF Thermoprep), acid salt Using a titrator (Metrohm, 848 Titrino) and the like to analyze the components and correct the lack of raw materials to prepare a reprocessing chemicals for reprocessing chemicals. Content analysis for the reprocessing chemical composition of Example 8 described in the regeneration solution and Korean Patent Application No. 10-2007-0002967 is shown in Table 1 to Table 5 and the conditions of the regeneration solution are shown in Table 6.

Examples 2-7

Through the process of obtaining the same reprocessing chemical composition and waste liquid described in Example 1, the operating conditions of the centrifuge were diversified, and impurities were removed as much as possible through a 0.1 μm filter process and reduced pressure distillation (10 mmHg, 60 ° C.).

Comparative Examples 1 to 6

Comparative Examples 1 to 5 are examples of the diversification of the centrifugation, the presence of a filter process, and the presence of a vacuum distillation process. Table 6 shows the conditions of the comparative example.

Composition change evaluation

In the Examples and Comparative Examples, the analyzer was compared with the reprocessing chemical composition of Example 8 described in Example 8 of Korean Patent No. 10-0842853. The results are shown in Table 7.

◎: The same or 95% or more similar ingredient ratio

X: 95% or less of the new component, or inefficient

yield

In Examples and Comparative Examples, yields were compared by a formula of (filtrate weight ratio / initial waste weight ratio) * 100% as a yield for the final filtrate which can be recovered and used in the initial waste liquid. However, in case of Comparative Example 3, the efficiency can be improved by high rpm and a lot of time, but it can be seen that it is not suitable in terms of equipment life and economics. It is more desirable to achieve optimum efficiency within a short period of time without overwhelming the equipment. The results are shown in Table 7.

◎: 90% or more removal yield

O: yield of 70% or more and less than 90%

X: removal yield within 70%, or inefficient

Peelability  evaluation

In the Examples and Comparative Examples, the defective panels were retreated at 60 ° C using a reprocessing chemical regeneration solution prepared by replenishing the shortage of components based on the results analyzed using the analyzer. The degree of peeling with reprocessing time was evaluated according to the following criteria, and the results are shown in Table 7.

◎: Completely removed within 15 minutes (new fluid level)

O: Completely removed within 20 minutes over 15 minutes

X: removed or not removed after more than 20 minutes, or inefficient

Solubility Assessment

In the Examples and Comparative Examples, the defective panels were retreated at 60 ° C using a reprocessing chemical regeneration solution prepared by replenishing the shortage of components based on the results analyzed using the analyzer. After peeling to check the solubility over the treatment time, the degree of filtration of the residue on the 0.1 μm mesh filter was evaluated according to the following criteria, and is shown in Table 7.

◎: no residue on 100μm mesh

X: Dross stuck in 100μm mesh, or inefficient

Service life evaluation

In the Examples and Comparative Examples, the defective panels were retreated at 60 ° C using a reprocessing chemical regeneration solution prepared by replenishing the shortage of components based on the results analyzed using the analyzer. In order to confirm the service life over the treatment time, the life was measured based on the fresh solution after peeling, and the results were evaluated according to the following criteria and shown in Table 7.

◎: Life span over 95% or new liquid level

○: life span of 90% or more and 95% or less

X: 90% or less lifespan, or inefficient

As can be seen from the results of the above examples and experimental examples, according to the purification and regeneration method of the present invention, it was possible to regenerate reprocessed chemical waste liquid, which had been difficult to regenerate in a good state, with high efficiency and by using an analyzer. By replenishing the shortage of raw materials, the company saved more than 70% of the cost compared to new liquid manufacturing. In addition, it was found that the reprocessing chemical regeneration solution prepared in Example maintained nearly equivalent performance in peelability, solubility, and service life compared to the fresh solution.

31: centrifuge 32: filter process
33: vacuum distillation process 34: analysis equipment

Claims (10)

(a) centrifuging the waste liquid of the aqueous reprocessing chemical comprising 5-30 wt% of dimethyl sulfoxide, 5-20 wt% of an inorganic alkali hydroxide and 15-30 wt% of a water-soluble amine compound;
(b) removing water by vacuum distillation with respect to the centrifuged supernatant to sludge the dissolved resin and to precipitate inorganic alkali;
(c) removing the sludged resin and the precipitated inorganic alkali;
and (d) analyzing and correcting the components of the liquid from which the sludged resin and the precipitated inorganic alkali have been removed. The method of claim 1, further comprising a filtration step of passing the supernatant centrifuged in step (a) through a membrane filter having a pore size of 0.1 ~ 10㎛ Purification and Regeneration Method. The method of claim 1, wherein the step (a) further comprises immersing the waste liquid prior to centrifugation and passing it through a mesh filter. The method of claim 1, wherein removing the resin and the inorganic alkali comprises removing by centrifugation or filtration. The method of claim 1, wherein the centrifugation is performed at a rotational speed of 1,000 to 15,000 rpm for 0.5 to 3 hours. The method of claim 5, wherein the centrifugation is performed for 1 to 2 hours at a rotational speed of 4,000 to 8,000 rpm. delete The method of claim 1, wherein the analyzing and calibrating comprises purifying and regenerating wastewater reprocessing chemical waste liquid for defective LCD panel processing including analyzing a component of a liquid by a quantitative and qualitative analyzer and correcting by a calibration program. Way. The method of claim 8, wherein the analyzer comprises an acid-base titrator, a gas chromatography, and a moisture analyzer. 10. The method according to any one of claims 1 to 6, 8 and 9, wherein the aqueous reprocessing chemical is 5-30% by weight of dimethyl sulfoxide; Inorganic alkali hydroxide 5-20 wt%; Water soluble amine compound 15-30 wt%; 1 to 10 wt% of a protic glycol-based organic solvent; 1 to 10% by weight of an aprotic glycol-based organic solvent; And a method for purifying and regenerating an aqueous reprocessing chemical waste liquid for treating defective LCD panels consisting of remaining water.

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