KR100869333B1 - Reproducing method of used propylene glycol monomethyl ether acetate - Google Patents

Abstract

A reproducing method of waste propylene glycol monomethyl ether acetate is provided to effectively remove pigment, photoresist, metallic ion and minute particles contained in the waste organic solvent generated in manufacturing a color filter. A reproducing method of waste propylene glycol monomethyl ether acetate comprises a distillation process which is constituted in 3 steps in order to distill a low-boiling point material and a high-boiling point material from a waste organic solvent from which the solid component and metallic component are removed; and a filteration process which constitutes a membrane filter of the Teflon material with 0.05 ~ 0.5 micrometer air gap in 3 steps and removes the minute particles from the waste organic solvent. The unnecessary photoresist is removed in a step for using the photoresist for the pigment blow nozzle cleaning and the pigment dispersion photolithography used in the TFT-LCD color filter manufacture.

Description

Recycling method of used Propylene Glycol Monomethyl Ether Acetate}

The present invention relates to a method for recycling waste PGMEA, and in particular, removes various organic solvent impurities, pigments and polymers contained in the waste PGMEA generated in the TFT-LCD color filter manufacturing process, and reuses them in the TFT-LCD manufacturing process. The present invention relates to a playback method that makes it possible.

Display (TFT-LCD) is a combination of two key elements to implement the function, the color filter and the TFT circuit (TFT-Array) substrate is the main component and the driver circuit including a driver IC in the periphery. .

The color screen of the TFT-LCD is achieved through the operation of TFT and Cell, which controls the transmittance with white light of the back light, and the additive mixed color of three primary colors coming out through the red, green, and blue color filters. There are two types of color filter: dye method and pigment method, depending on the organic filter material used in the manufacturing process. The color filter can be classified into dyeing method, spraying method, electrodeposition method, printing method, etc. A common method used is pigment spraying. After spraying each color, the spray nozzle should be cleaned with organic solvent. PGMEA electronic solvent is used because it is easy to clean and metabolize during human inhalation.

Photolithography is used in the application of red pigments, green pigments, and blue pigments. A photoresist, a photosensitive material, is mixed with a pigment and irradiated with light or laser through a pattern printed mask. It is a process of transferring the circuit pattern of a mask to a board | substrate. In this process, the photoresist (negative color photo resist) remaining in the area where no photoresist reaction occurs due to no light is irradiated with organic solvent. PGMEA, which is used for color filters, is also used here because of its cleaning power and low toxicity.

The waste PGMEA used in the color filter manufacturing process has been incinerated because it cannot be reused by a simple reprocessing facility because of pigments, pigment dispersants, photoresists, moisture mixed during cleaning, and metallic materials. In addition, some regeneration companies are not able to remove impurities such as MMP and cyclohexanone, which are impurity solvents, and cannot produce more than 99.0% of purity.

Therefore, in order to recover PGMEA from waste PGMEA, it is necessary to separate and remove impurities such as pigments, photoresists, and metal components.

The photoresist is composed mainly of polymer materials such as PAC, copolymer, photopolymerization initiator, crosslinking agent and other additives, and these are solid materials dissolved or dispersed in an organic solvent. In addition, in the recovery of the organic solvent, not only the pigment and the photoresist component, but also the metal ion component in the organic solvent should be removed.

In order to regenerate the organic solvent containing impurities, a technique of separating the solid pigment, the photoresist and the liquid organic solvent is required. In general, the separation of the solid-liquid phase is performed by filtration, precipitation, coagulation precipitation, centrifugation, and the like. This is used.

However, dissolved pigments and photoresists may be partially precipitated by natural precipitation for a long time, but need a long time and cannot be applied commercially. The above-mentioned precipitation method requires additional chemical treatment to precipitate dissolved components and is completely separated. Is impossible. Some flocculants may react with the main constituents resulting in PGMEA loss.

After removing the solids, other organic solvent impurities contained in the waste PGMEA are operated in a distillation column to remove the low boiling point component and the high boiling point component. These impurity organic solvents are solvents such as alcohols, esters, ethers, glyme (glycol diethers), ketones, and the like, which are used to bring various materials used in the photoresist into solution.

Among them, MMP and cyclohexanone are the most difficult to separate from PGMEA due to the close difference in boiling point.

In addition, in the distillation column during the recovery of the organic solvent, metal ions should not be eluted from the organic solvent.

The product produced by distillation also contains very fine particles that are mixed in the process and product tanks. These fine particles are used in the electronics industry, so that the fine particles in the organic solvent remain in the color filter and thus have defects in light transmittance. It may also cause management of waste PGMEA used in color filters. These microparticles are presumed to be mainly in the form of inorganic matters such as dust floating in the air or in the form of organic matter which does not dissolve in the organic solvent, but should be removed at a very low level regardless of the kind.

As described above, it is required to remove the impurity organic solvent components, pigments, photoresist, metal ions, and fine particles contained in the waste organic solvent, so that the development of the technology is required.

The present invention was created to solve the problems related to the conventional waste PGMEA regeneration, waste PEMEA to effectively remove the pigments, photoresist, metal ions and fine particles contained in the waste organic solvent generated in the color filter device manufacturing process Its purpose is to provide a regeneration method.

Checkpoints, etc., in laboratory and field applications are described in detail in the Examples of the present invention. Further objects and advantages of the invention can be realized by means and combinations indicated in the claims.

In order to achieve the above object, the present invention provides a method for regenerating waste organic solvent used to remove unnecessary photoresist from a spray nozzle and a peripheral device in the step of using a photoresist in the manufacture of a color filter, by distilling the waste organic solvent to waste oil. The continuous first distillation step of removing and removing the photoresist solids and metal components contained in the solvent to the bottom of the distillation column and recovering the waste organic solvent, and continuously operating the two distillation towers with the waste organic solvent recovered through the distillation step. A low boiling point material and a high boiling point material are separated by a distillation method, and the produced PGMEA product is filtered to provide a method for regenerating a waste organic solvent comprising a filtration step of removing fine particles in the waste organic solvent.

It is preferable that 25 to 30% by weight of solids are discharged to the bottom of the distillation column together with the organic solvent with respect to 70 to 75% by weight of PGMEA which is recovered to the top of the distillation column in the first distillation process.

In the second distillation process, 5-10 wt% of water and low boiling organic matter are separated from the top of the distillation column based on the secondary distillation column feed solution, and 5-10 wt% of the high boiling point material is removed from the third tower.

The organic solvent recovered by the regeneration method controls the distillation column operation and facility so that each metal component remains below 10 ppb. In particular, it is important to ensure that no metallic components are eluted from the device.

Finally, in the particulate matter filtration process, it is economical to remove the particles having a larger particle diameter by using a filter having a pore diameter of 0.05 μm to 0.5 μm in three stages. The filter medium should use a membrane membrane filter made of Teflon.

The PGMEA solvent filtered by the regeneration method should be such that less than 40 fine particles remain on the basis of particles having a size of 0.5 μm per 1 ml of the organic solvent.

As described above, according to the waste PGMEA regeneration method of the present invention,

First, the impurity organic solvent components, pigments, photoresists, metal ions and microparticles contained in the waste PGMEA used during the removal of the photoresist, which are not necessary to be removed after the nozzle and exposure in the step of using the pigment and the photoresist in the production of the color filter. By removing ingredients, moisture, etc., it can be reused in the color filter manufacturing process of the TFT-LCD manufacturing process.

Second, in the distillation process, first, the conditions are set to minimize the adhesion of solids such as pigments and photoresist to the bottom of the distillation column to devices such as heating surfaces, and the discharge viscosity standards are provided to minimize the loss of active ingredients and then continuously In the operating distillation column process, the difficulties can be eliminated in advance.

Third, domestic recycling companies cannot produce more than 99.0% of PGMEA even when using the same raw material, so they are sold to the general solvent market, so that the profitability is low and the cost reduction of customers can not be contributed. By operating at atmospheric pressure in the distillation process for organic solvent separation, the relative volatility is increased to effectively separate.

Fourth, the organic solvent is recovered from the first and third distillation column to the top, and the metal contained in the waste organic solvent can be easily removed by stable reflux conditions.

Fifth, by designing and applying a multi-stage filtration process, it is possible to effectively filter the microparticles contained in the waste organic solvent and to make the filtration life long, and to perform economic filtration.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

 Referring to Figure 1 will be described a method for regenerating the waste organic solvent according to an embodiment of the present invention.

 1 is a process flowchart of a method for regenerating waste PGMEA according to an embodiment of the present invention.

Waste organic solvent recycling method according to an embodiment of the present invention is the first distillation step (D-100), the second distillation step (D-200), the third distillation step (D-300) and the filtration step (F- 400).

The first distillation step (D-100) is a process of distilling the waste organic solvent to concentrate and remove the pigment, photoresist and metal components contained in the solvent to the bottom of the distillation column. This distillation process remains in the portion of the photoresist that is not irradiated with light (plasma or laser light) during the manufacturing of color filters, so that the material that is not thermally cured is discharged after being washed with a solvent. Must be operated to minimize scaling. It should be operated continuously at 80 ~ 100 ℃ temperature condition under vacuum condition.

The crude PGMEA recovered to the upper part of the distillation column (D-100) is supplied to the second distillation column (D-200) after condensation to remove moisture and low boiling point material, and the lower material of the second distillation column is supplied to the third distillation column (D-300). Remove high boiling point material. In the second and third distillation columns, unlike the operating conditions of the first distillation column, the boiling point of MMP and cyclohexanone is close to each other, so that the relative volatility between materials during distillation is reduced by vacuum operation. Let it drive

 The metal ion component contained in the waste organic solvent may be removed in the three-stage distillation process because it moves to the bottom of the distillation column. Accordingly, the present invention can simply remove the metal ions contained in the waste organic solvent by recovering the organic solvent from the top of the distillation column. The distillation column should be made of stainless steel, pickled before use, and constructed with materials that do not elute metal components such as gaskets. In the distillation column, if flooding occurs due to an overload condition, the metal ions are discharged to the upper part of the distillation column.

The atmospheric distillation column operating conditions are the temperature of the secondary distillation column is 100 ~ 160 ℃, the temperature of the third distillation column is operated about 150 ~ 180 ℃.

 The filtration step (F-400) is a step of filtering the organic solvent recovered through the distillation step to remove fine particles in the organic solvent. The filtration step (F-400) is a step of removing particulate matter as a final step to remove particles having a large particle size by using a filter having a pore diameter of 0.1 μm to 0.5 μm in three stages. The filter medium uses a membrane membrane filter made of Teflon. The PGMEA solvent filtered by the regeneration method may allow the fine particles to remain at 40 or less on a particle size of 0.5 μm per 1 ml of the organic solvent.

Waste organic solvent recovery method according to an embodiment of the present invention as described above is used to recover the waste organic solvent propylene glycol monomethyl ether acetate (PGMEA) discharged to the waste liquid in the color filter process.

In addition, the organic solvent recovered by the waste organic solvent recovery method according to an embodiment of the present invention, sodium (Na), magnesium (Mg), aluminum (Al), potassium (K), calcium (Ca), chromium (Cr ), Manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), tin (Sn), and lead (Pb) can each contain 10 ppb or less. .

The recovered and recycled organic solvent may contain 40 particles or less per 1 ml of the organic solvent on the basis of 0.5 μm particles.

Hereinafter, the three-stage filtration process of the present invention will be described with reference to FIG. 2.

In order to examine the removal efficiency of the organic solvent component, pigment, photoresist, metal component and fine particles in the method of regenerating the waste organic solvent according to the present invention, the following examples and comparisons are made with respect to the waste PGMEA generated in the color filter manufacturing process. Experiment by example.

Here, the components contained in the waste PGMEA are shown in Table 1 below.

ingredient PGMEA waste solution, wt% Boiling point, ℃ moisture 2 100  Organic solvent composition type Low boiling point 2 MMP 1.5 142 PGMEA 81 146 Cyclohexanone 1.5 156 Other high boiling point 7 Nonvolatile Solids            5 N.A

The organic solvent MMP stands for methyl-3-methoxy propionate, PGMEA stands for propylene glycol monomethyl ether acetate, and cyclohexanone is simply called anone. Lose. Low-boiling and other high-boiling components contain a number of components, but only the three components that are difficult to separate or are intended for recovery are described.

First, in order to find out the removal efficiency of the pigment and photoresist, the impurity organic solvent separation efficiency, the metal component identification and the particle removal efficiency of the waste organic solvent recycling method according to the present invention, the waste PGMEA generated in the color filter manufacturing process Experimental and actual operation was carried out through Examples 1 to 7 below.

Example 1

In order to remove the pigment and photoresist solids contained in the waste PGMEA solvent, a sedimentation test was conducted using a centrifuge, but no separation was performed at 1 wt% or less of the total solid amount of the solid state. 0.5% by weight of 20% caustic soda solution was added to the raw materials, and after mixing, the sediment of 4-5% of the sediment was separated from the centrifuge. Precipitation was improved, but the main component, PGMEA, reacted with caustic soda to increase PGME (Propylene glycol monomethyl ether) component, resulting in loss of principal component. Other flocculating organic flocculants have also been applied but could not be applied due to the strong solvent properties of PGMEA itself.

Example 2

The distillation process was tested using a single distillation apparatus made of flasks. The distiller was supplied with a heat source from the electric mantle, the condenser was operated using cooling water at room temperature, the organic solvent was discharged to the top of the tower, and the organic solvent discharged to the top of the tower while observing the properties of the remaining liquid in the flask. When the discharge rate was over 75%, solids adhered to the bottom of the flask. Separately, in order to confirm the amount of pigment and photoresist solids, the amount of evaporated residue was measured by using an evaporating dish, and the result was 4 to 5% by weight.

Example 3

As a result of distillation test, the condensate obtained by performing 75% single distillation in Example 2 was refluxed in a pilot distillation column having a theoretical stage of 28 stages. The general distillation separation rate is improved as the degree of reflux is improved.

Example 4

Due to the problem in Example 1, it was difficult to separate the precipitates, and the solid phase component was discharged to the bottom and the organic solvent was recovered to the top of the column without reflux in the 15-stage distillation column due to concentration separation. The bottom of the tower is a reflower that supplies heat, and the scale of the reboiler heat transfer tube surface is severe as a natural convection, and a circulation pump is installed to improve heat transfer efficiency by installing a circulation pump to prevent deposition and minimize solvent loss. Emissions of the lower solids are managed by checking the viscosity and tracking the circulation to determine emissions. It is appropriate that the viscosity be sampled from a circulation pump and that the viscosity level be maintained at 10 ± 2 cP (50 ° C).

Example 5

The secondary distillation column was selected using the test result of Example 3. Secondary distillation columns should minimize the most problematic MMPs for the production of more than 99.0% by weight of PGMEA, the purity level required by the customer. Therefore, the optimal condition was selected by selecting a distillation column of 110 stages. In this case, the optimum condition means that the operating pressure is operated under normal pressure conditions and the optimum reflux amount is used to improve the relative volatility.

Example 6

In Example 5, the lower portion of the second distillation column, which minimizes the boiling point and MMP, is supplied to the third distillation column to remove the cyclohexanone component and the metal component from the third distillation column. In the third distillation column, the distillation column having 100 stages was selected to select the optimum conditions.

In this case, the optimum condition means that the operating pressure is operated under normal pressure conditions and the optimum reflux amount is used to improve the relative volatility. In particular, operating conditions must be stabilized to prevent metals from reaching the top of the tower.

In order to prevent the elution of metals, the tertiary distillation column should be made of stainless steel and Teflon materials for the main equipment and piping components. In particular, pipe parts made of stainless steel should be treated with nitric acid cleaning or electropolishing to prevent iron from eluting.

Example 7

By the above process, in order to remove the fine particulate matter, PGMEA having purity and metal content within the specification range, the particulate filter is removed by passing the membrane filter made of Teflon in three stages from the largest to the smallest pore.

In order to remove particulate matter contained in these electronic solvents, a company that manufactures a filtration device has already specially formulated a filtration medium and has a target material. However, the most economic filtration method is a process application technology of a manufacturer producing a solvent. .

The results of the experiment and application operation performed at each step of Examples 1 to 7 are shown in the following tables.

Coagulation Test Results in Example 1 ingredient Caustic soda before treatment After caustic soda treatment moisture 2 2  Organic solvent composition type Low boiling point component,% 2 2 PGME,% 5 MMP,% 1.5 1.5 PGMEA,% 81 75.9 Cyclohexanone,% 1.5 1.5 Other high boiling point components,% 7 7 Non-volatile solids,% 5 5.1

Pilot distillation column test results in Example 3: Separation efficiency comparison,% Atmospheric pressure Vacuum condition  Organic solvent composition type Low boiling point component,% 7 5 MMP,% 5 2.5 PGMEA,% 85 88 Cyclohexanone,% One 2.5 High boiling point component,% 2 2 Operating conditions Tower Top Pressure, mmHg 780 -600 ± 20  Reflux Conversion Conversion

Actual distillation column test operation results in Example 5: Secondary distillation column Tower top Bottom of the tower  Organic solvent composition type Low boiling point component,% 14.9 0.05 MMP,% 10 0.5 PGMEA,% 75 86 Cyclohexanone,% 0.05 1.5 High boiling point component,% 0.05 11.95  Operating conditions Operating pressure, mmHg 0 0.5 Operating temperature, ℃ 110 160 Reflux 20

Actual distillation column test operation result in Example 6: Third distillation column Top top (product) Bottom of the tower  Organic solvent composition type Low boiling point component,% 0.04 0.15 MMP,% 0.6 0.1 PGMEA,% 99.1 54.75 Cyclohexanone,% 0.26 5 High boiling point component,% 40  Operating conditions Operating pressure, mmHg 0 0.2 Operating temperature, ℃ 150 175 Reflux 2

Analysis of the tower top product during the actual distillation column test operation in Example 6: Third distillation column Metal ion concentration, parts per billion (ppb) Na Mg Al K Ca Cr Mn Fe Ni Cu Zn Sn Pb Run-1 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less Run-2 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less Run-3 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less

   Metal ions were analyzed by an inductively coupled plasma mass spectrometer (ICP-MS ELAN DRC-2) of Perkin Elmer, USA.

The number of fine particles (size 0.5 micron or more) as a result of filtration using the actual product produced in Example 7 Filter Size Pore Size Classification Before filtration Primary filter 0.5 micron Secondary filter 0.1 micron Tertiary filter 0.05 micron Run-1 1,000 or more 254 45 15 Run-2 1,000 or more 218 56 21 Run-3 1,000 or more 267 62 18

Microparticle analysis was performed with a light scattering particle analyzer (KS-40B) manufactured by Rion of Japan.

As described above, the present invention has defined the claims according to the embodiments described in the drawings and the examples produced in the actual process for the waste PGMEA regeneration generated in the color filter manufacturing process.

1 is a process chart of the regeneration method of waste PGMEA according to an embodiment of the present invention.

Figure 2 is a filtration process of the waste PGMEA according to an embodiment of the present invention.

Claims (5)

A distillation process comprising three steps to discharge and remove the photoresist solids and metal components contained in the waste organic solvent to the bottom of the distillation column, and to distill the low and high boiling point substances from the waste organic solvent from which the solids and metal components are removed; And a filtration process for removing fine particles in the waste organic solvent by constructing a membrane filter made of a Teflon material having a pore size of 0.05 to 0.5 μm in three stages, and cleaning a pigment spray nozzle and a pigment dispersion method used for manufacturing a TFT-LCD color filter. In the regeneration method of waste PGMEA used to remove unnecessary photoresist in the step of using a photoresist for lithography, In the distillation process, PGMEA discharges the removed solids to the bottom of the distillation column and discharges steam to the top of the distillation column so as to continuously distill MMP and cyclohexanone having a large impurity ratio to maintain purity of 99.0 wt% or more, Set the vacuum pressure and atmospheric pressure operation conditions, set the first distillation column at 80 ~ 100 ℃ as the vacuum pressure operation condition, the second distillation column at 100 ~ 160 ℃ and the third distillation column at 150 ~ 180 ℃ as the normal pressure operating condition, respectively. Regeneration method of lung PGMEA characterized in that delete The method of claim 1, The recovered PGMEA is recycled to the waste PGMEA, characterized in that the MMP is 0.5 to 0.6% by weight, cyclohexanone is 0.2 to 0.3% by weight. delete The method of reclaiming waste PGMEA according to claim 1, wherein the recovered PGMEA has a residual content of a metal component of 10 ppb or less for each metal component.

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