KR101986367B1 - Recovery method of the organic solution from the waste result solution of polyimide production process and its production system - Google Patents

Abstract

The present invention relates to a method for recovering an organic solvent generated after manufacturing a polyimide film for semiconductors and flexible displays. The method of the present invention comprises: a reaction waste solvent filtration step (S1); a reactive distillation step (S2); a cooling reflux step (S3); a neutralization adsorption step (S4); and a fractional distillation step (S5). Recycling the solvent not only reduces manufacturing cost but also dramatically increases polyimide productivity.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyimide film for a semiconductor and a flexible display,

TECHNICAL FIELD The present invention relates to a method for recovering an organic solvent that occurs when a semiconductor and a display polyimide film are produced, and a device suitable for the recovery method.

In the fields of displays using organic electroluminescent devices and display devices such as liquid crystal displays, etc., it has been required to have light transmittance as well as glass, sufficiently high heat resistance, and appearance of a light and flexible material. As a material for use in such glass substitute applications, a film including a highly heat-resistant, lightweight and flexible polyimide has been developed.

Thermosetting polyimides are known to have thermal stability, chemical resistance, stable mechanical properties and unusual orange / yellow color.

In general, a polyimide (PI) film is a film made of a polyimide resin. The polyimide resin is produced by preparing a polyamic acid derivative by combining an aromatic dianhydride and an aromatic diamine or an aromatic diisocyanate in solution, Refers to a high heat-resistant resin produced by imidization.

In producing such a polyimide, a dianhydride component and a diamine component are subjected to condensation polymerization in an organic solvent to synthesize a desired film. The organic solvent used after the synthesis is mixed with organic solvent including acetic acid, reaction catalyst, water and the like.

Organic solvent is a special chemical substance in the first disposal process, and it is a root cause of cost increase and environmental pollution because it has to undergo strict treatment procedure according to separate waste treatment law.

In order to extract and recycle only organic solvent, incineration treatment is carried out at a high cost in disposal, and relatively expensive organic solvents are also incinerated, resulting in waste of resources as well as environmentally unfavorable results have.

Korean Patent Laid-Open No. 10-2016-0102378, which is disclosed in the patent documents of the prior art documents, discloses a process for preparing a pressure-sensitive adhesive composition comprising the steps of: a) dispersing a dianhydride compound and a diamine compound in water; b) Filtration and drying of the reaction product obtained by reacting the dianhydride compound and the diamine compound at a temperature of from room temperature to room temperature to obtain a polyimide in a single reaction step, and c) separating the water vapor produced in step b) Withdrawing, cooling and condensing the water to recover the water. And recovering the water produced after the reaction.

The present invention provides a new manufacturing method for solving the problem of disposal of expensive organic solvent by using water instead of organic solvent as a reaction solvent and suggesting a way to avoid the use of organic solvent. It is a difficult reality to apply in synthesis method.

KR 10-1755251 B1 2017.07.07

It is an object of the present invention to provide a method for recovering and recycling an expensive organic solvent in a solution for post-reaction discarding treatment after synthesis of the polyimide, and a suitable apparatus therefor.

In order to solve the problem that it is difficult to separate them by a fractional distillation method due to the presence of an organic solvent, acetic acid, catalyst, water and the like in the residual waste liquid after the synthesis reaction of the polyimide by the condensation reaction of an acid and an alcohol, After conversion to the ester, the organic solvent was fractionally distilled at a high price by removing it.

Accordingly, the present invention relates to a process for producing a polyimide for semiconductor or flexible display, which comprises a reaction waste solvent filtration process for recovering a reaction waste solvent comprising organic and aqueous and a solid particle mixture, A reactive distillation step for esterifying the acetic acid contained in the reaction waste solvent by adding alcohol and acid to the waste solvent, and an azeotropic mixture of the ester compound, water, and alcohol generated through the above reactive distillation step are cooled with a cold condenser, A cooling reflux step of repeating a step of separating the water from the decanter and feeding the ester compound and the alcohol into the reaction tank except for the water, and the step of adding the alkali to neutralize the acid in the reaction tank when the acetic acid content of the reaction waste solvent becomes low to the desired level A neutralization adsorption step of adsorbing and removing unreacted materials and other suspended matters, And a fractional distillation step of fractionating an organic solvent, an alcohol and a water mixture passed through an adsorption column, and separating the objective organic solvent into a high purity, and a method for recovering an organic solvent after the production of a semiconductor and a polyimide film for a flexible display It is characterized by.

The reactive distillation process is characterized in that an alcohol and an acid are added to the filtered reaction waste solvent and reacted in the same manner as in CH ₃ COOH + ROH <-> ROAc + H ₂ O. Wherein R is any one selected from the group consisting of methyl, ethyl, n-propyl and isopropyl, and Ac is an acetyl group.

In the cooling and reflux process, the alcohol and water containing esters produced by the reactive distillation process are separated in a decanter, and only the alcohol and ester in the upper layer are refluxed into the reaction tank.

In the neutralization adsorption step, when the acetic acid concentration is lower than the target value, the added acid catalyst is neutralized with an alkali, more preferably, caustic soda to remove the acid, and the unreacted acetic acid and the impurities are reacted with activated carbon, zeolite, silica gel, Alumina, or a mixture thereof is passed through an adsorption column filled with an adsorbent.

The above-mentioned fractionation process is characterized in that a mixture of an organic solvent, alcohol and water in which unreacted acetic acid and impurities are removed by passing through an adsorption column is purified by fractional distillation.

And the present invention, and kept at the temperature suitable for reaction by a heating apparatus, the inside is installed with a stirrer for stirring the reaction _{liquid, CH 3 COOH + ROH <-} > ROAc + H 2 O Equation (in which R is (Wherein A is an acetyl group), and a reaction tank in which a reaction of the ester compound with an alcohol or the like is induced in a multi-stage A cooling condenser for cooling the azeotropic mixture of the ester compound, water and alcohol produced through the reaction tower and supplying the cooled azeotrope to the decanter, and a cooling and condensing device for cooling and condensing the azeotrope, A reflux decanter for removing water and alcohol from the lower part of the phase-separated product and for refluxing the upper ester compound and the alcohol, and And an adsorption device for collecting the desired organic solvent by adsorbing the unreacted material and other impurities by neutralizing the alkali by neutralizing the acid in the reaction tank when the concentration of the acetic acid is measured below the target value, Another feature of the present invention is an apparatus for recovering an organic solvent after manufacturing a semiconductor and a polyimide film for a flexible display.

In the reflux decanter, the lower water and the alcohol are discharged to the outside of the reaction system,

And further refluxing the upper ester compound and the alcohol to the upper part of the reaction tower.

The present invention relates to a continuous high purity purification of an organic solvent that relies on incineration disposal, which enables recycling of a solvent generated during a continuous polyimide chemical reaction to reduce the cost and enable a dramatic increase in polyimide productivity by continuous re- It is effective.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process drawing showing the overall process of the present invention,
2 is a block diagram of an apparatus suitable for the process of the present invention.

A method of recovering organic solvent generated after manufacturing a semiconductor and a polyimide film for a flexible display according to the present invention will be described in more detail with reference to the accompanying drawings.

The reaction in the present invention is a synthesis reaction of amine-based monomers for the synthesis of polyimide polymers, and a detailed description of these synthesis reaction steps will be omitted. In the present invention, the reaction waste solution or the reaction waste solvent after the synthesis reaction is a waste solution obtained by mixing residual organic solvent, catalyst, water, etc. after the synthesis reaction.

In the present invention, the synthesis reaction of a polyimide used for a semiconductor and a flexible display includes a unit structure derived from a diamine-based monomer and a unit structure derived from a dianhydride-based monomer, and pyromellitic acid dianhydride (PMDA) or biphenyltetracarboxylic acid dianhydride (BPDA). The aromatic diamine components include oxydianiline (ODA), p-phenylenediamine (p-PDA), m-phenylenediamine -PDA), methylene dianiline (MDA), bisaminophenylhexafluoropropane (HFDA), etc. are mainly used. A description of these synthetic reaction monomers and various synthetic reaction raw materials free of them and a description of the synthetic reaction thereof will be omitted.

The organic solvent (first solvent) for solution polymerization of the monomers in the synthesis reaction is not particularly limited as long as it is a solvent that dissolves the polyamic acid. Examples of the organic solvent (first solvent) include m-cresol, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulfoxide, At least one polar solvent is used. In addition, a low boiling point solution such as tetrahydrofuran (THF), chloroform or a low-absorbency solvent such as? -Butyrolactone may be used.

In the present invention, the production method of the polyimide resin through the reaction of the diamine-based dianhydride monomer is not particularly limited, and the use of various solvents used in these reactions and the recovery thereof for recycling the high purity organic solvent And the scope of the present invention is not limited by these examples.

The organic solvent is used in an amount sufficient to enable a sufficient reaction of the monomers, and usually 9 to 15 times the weight of the monomer is used.

After the reaction, acetic acid is generated by the reaction between the dehydration catalyst and water, and an azeotrope mixture is formed with various catalysts and acetic acid, water, DMF, methylpyridine and the like, and by simple fractional distillation, It is impossible to separate them.

In the present invention, the acetic acid remaining after the reaction is condensed with an alcohol to convert it into an acetic acid ester, so that it can be separated from the organic solvent and fractional distillation is carried out to purify the waste organic solvent with high purity.

 In the specific recovery method of the present invention,

A reactive waste solvent filtration step (S1) for recovering a reaction waste solvent comprising organic and aqueous and solid particle mixture generated in a polyimide synthesis process for a semiconductor or a flexible display to filter solid particles contained therein,

A reactive distillation step (S2) of esterifying the acetic acid contained in the reaction waste solvent by adding alcohol and acid to the filtered reaction waste solvent;

The ester compound produced through the above reactive distillation process, the azeotropic mixture of water and alcohol is cooled with a cold condenser, and after cooling, the mixture liquid is separated from the decanter, and then the ester compound and water except for water are fed to the reaction vessel A cooling and reflux step (S3)

A neutralization step (S4) of neutralizing the neutralized acid by neutralizing the acid in the reaction tank when the acetic acid content of the reaction waste solvent is lowered to a desired level, and adsorbing and removing unreacted materials and suspended matters;

(S5) for fractionating a mixture of an organic solvent, an alcohol and water having passed through an adsorption column and separating a desired organic solvent into a high purity (S5). The organic solvent after the production of a semiconductor and a polyimide film for a flexible display Recovery method.

Exemplary embodiments of each of the above processes will be described with reference to the accompanying flow chart of FIG. 1 and an apparatus suitable for the process of FIG.

One. Reactive waste solvent  Filtration step (S1)

 Is composed of a waste oil agent, acetic acid, water, and other impurities produced in the process of producing a polyimide film for a flexible display. The content of the organic solvent in the reaction waste solvent is 30 to 90% by weight, the content of acetic acid is 2 to 30%, the content of the catalyst is 2 to 10%, and the content of moisture is 1 to 60%. In addition to these liquid solvents, various fine suspended particles are contained in the recovery process, and these solid particles are removed.

2. Reactive distillation process (S2)

The esterification reaction between acetic acid and alcohol is induced by adding an alcohol and an esterification catalyst to a reaction solvent in which fine suspensions or solid particles have been removed.

The reactive waste solvent remaining after the synthesis reaction is composed of 2 to 30% of acetic acid, 30 to 90% of organic solvent, 1 to 60% of water and 2 to 10% of catalyst based on the total weight, Is from 2 to 30% at most, and the esterification with alcohol continuously proceeds as in the following formula, and the resulting ester is continuously recovered.

CH ₃ COOH + ROH <-> ROAc + H ₂ O

(Wherein R is any one selected from the group consisting of methyl, ethyl, n-propyl and isopropyl, and Ac is an acetyl group).

 As described above, esters formed by the reaction of acetic acid and alcohol are converted into acetic acid ester by reactive distillation and removed by azeotropic mixture of water and alcohol.

3. Cooling Reflow Process (S3)

Water, alcohol, and acetic acid ester are evaporated into a complex azeotrope in the ester compound reacted by the reactive distillation process, and condensed while passing through the cooling bath (6)

The condensate, which has passed through the cooling bath, is separated into two layers and collected in decanter (7). In the pooled mixture, the upper layer of ester and alcohol is refluxed to bring back the contained alcohol back into the reaction and the lower layer separates the mixture of water and alcohol. The esterification reaction was promoted by maintaining the alcohol at a high concentration due to the reflux of the alcohol in the reversible esterification reaction. In the esterification reaction, the acetic acid is converted into the acetic acid alkyl ester form, and the alcohol is continuously separated and removed together with water.

4. Neutralization process (S4)

When the concentration of acetic acid is lowered below the target value by continuously scanning the acetic acid concentration as the fractional concentration process proceeds, the added acidic catalyst is neutralized with alkali, more preferably, caustic soda to remove the unreacted acetic acid and impurities It is removed by passing through an adsorption column. The adsorption column is a structure packed with an adsorbent such as activated carbon, zeolite, silica gel, or activated alumina.

5. Fractional Distillation Process (S5)

After the adsorption treatment through the neutralization adsorption process, the mixture of the organic solvent, alcohol and water is fractionally distilled to separate the desired organic solvent with high purity.

An apparatus suitable for the above-described process of the present invention will be described with reference to the process configuration diagram of FIG.

The present invention relates to a reaction tank (1) which maintains a temperature suitable for a reaction by a heating device (2) and in which an agitation device (3) for stirring a reaction liquid is provided,

When acetic acid contained in the reaction waste solvent is esterified by adding alcohol and acid to the reaction waste solvent in the reaction tank 1, a multi-stage tray or packing structure for inducing stripping of the reacted ester compound and alcohol or the like A reaction tower (5)

A cooling condenser (6) for cooling the azeotropic mixture of the ester compound produced through the reactive distillation process with water and the alcohol to supply the cooled azeotrope to the decanter,

A reflux decanter (7) for inducing phase separation of the cooled and condensed by the cooling condenser (6), removing water and alcohol in the lower part of the phase separated and refluxing the upper ester compound and alcohol to the upper part of the reaction tower,

When the concentration of acetic acid is measured to be lower than the target value, alkali is neutralized by neutralizing acid in the reaction tank (1), and unreacted materials and other impurities are removed by adsorption to remove the desired organic solvent And an adsorption device (8) for collecting the adsorbent.

The reaction tank 1 is maintained at a temperature suitable for the reaction by the heating device 2 and an agitation device 3 for stirring the reaction liquid is provided therein,

 The following formula

CH ₃ COOH + ROH <-> ROAc + H ₂ O

(Wherein R is any one selected from the group consisting of methyl, ethyl, n-propyl and isopropyl, and Ac is an acetyl group)

.

In FIG. 2, the thermometer 4 can be visually observed from the outside and remotely controlled by a remote sensing device.

 Experiments were conducted to collect 1000 g of the actual reaction waste solvent of the present invention and collect it. [Example 1] exemplifies a representative embodiment of the present invention. The technical scope of the present invention is not limited to the reaction conditions set forth in the examples, but can be carried out by changing various reaction conditions. An example is one example of various implementations.

 1,000 g of a reaction waste solvent generated in the production of a flexible display film having a composition of 70.5% DMF, 14.5% acetic acid, 3.2% 3-methylpyridine, 10.2% moisture and 1.6% other impurities was filtered through a microfilter, (4.8 mol, 200% of theoretical value) and 20.0 g of 98% sulfuric acid were charged into a reactor equipped with a decanter and heated. The resulting methyl acetate was evaporated immediately after forming an azeotropic mixture with methanol (azeotropic temperature 53.8 ° C) and water (azeotropic temperature 56.1 ° C), concentrated through a distillation column, liquefied through a heat exchanger, Upper layer: methyl acetate + methanol; lower layer + methanol). The mixture of methyl acetate and methanol in the upper layer is returned to the upper part of the column (Reflux). The methyl acetate content is increased and the methanol is circulated to promote the reaction and the lower methanol and water mixture are continuously separated and removed to promote the esterification reaction. When the acetic acid content in the reactor becomes insignificant, no further water is produced due to the reaction and the layer is not separated. The excess methanol is fractionated, neutralized with 20% caustic soda to pH 6-7 and passed through a column filled with activated carbon Trace amounts of acetic acid and impurities were removed. The treated solution (containing 2-Methylpyridine, DMF and water) was fractionally distilled to obtain 637.5 g (yield> 90%) of DMF having a purity of 99.5%.

1: Reactor 2: Heating device
3: stirrer 4: thermometer
5: Reaction tower 6: Refrigerated condenser
7: reflux decanter 8: adsorption device
S1: Reaction waste solvent Filtration S2: Reactive distillation process
S3: cooling and refluxing step S4: neutralization adsorption step
S5: fractional distillation process

Claims (7)

A reactive waste solvent filtration step (S1) for recovering a reaction waste solvent comprising an organic, aqueous and solid particle mixture generated in a polyimide synthetic process for a semiconductor or a flexible display to filter solid particles contained therein;
A reactive distillation step (S2) of esterifying the acetic acid contained in the reaction waste solvent by adding alcohol and acid to the filtered waste solvent;
The ester compound produced through the above reactive distillation process, the azeotropic mixture of water and alcohol is cooled with a cold condenser, and after cooling, the mixture liquid is separated from the decanter, and then the ester compound and water except for water are fed to the reaction vessel A cooling reflux process (S3);
A neutralization process (S4) for neutralizing the acid by neutralizing the acid in the reaction tank when the acetic acid content of the reaction waste solvent is lowered to a desired level, and adsorbing and removing unreacted materials and suspended matters;
(S5) for fractionating a mixture of an organic solvent, an alcohol and water, which have passed through an adsorption column, in a high purity by separating a target organic solvent (S5). Lt; / RTI &gt;
The method according to claim 1,
The reactive distillation step (S2)
A method for recovering an organic solvent after a polyimide film for a semiconductor and a flexible display is produced by adding alcohol and an acid to a filtered reaction waste solvent and reacting according to the following formula.
CH ₃ COOH + ROH <-> ROAc + H ₂ O
Wherein R is any one selected from the group consisting of methyl, ethyl, n-propyl and isopropyl, and Ac is an acetyl group.
The method according to claim 1,
The cooling and reflux process (S3)
Alcohol and water containing esters produced by the reactive distillation process are separated in decanter,
Characterized in that only the ester and alcohol in the upper layer are refluxed in the reaction tank, and a method for recovering the organic solvent after the production of the semiconductor and the polyimide film for flexible display.
The method according to claim 1,
The neutralization adsorption step (S3)
When the acetic acid concentration is lower than the target value, the added acid catalyst is neutralized with an alkali to remove the acetic acid, and the unreacted acetic acid and the impurities are adsorbed in an adsorption column filled with an adsorbent made of activated carbon, zeolite, silica gel, activated alumina, And removing the organic solvent after the polyimide film for semiconductor and flexible display is manufactured.
The method according to claim 1,
The fractional distillation step (S4)
Wherein the mixture of organic solvent, alcohol and water is passed through an adsorption column to remove unreacted acetic acid and impurities, and the mixture is purified by fractional distillation to recover a polyimide film for a semiconductor and a flexible display.
A temperature suitable for the reaction is maintained by the heating device 2, and an agitating device 3 for stirring the reaction liquid is provided inside,
The following formula
CH ₃ COOH + ROH <-> ROAc + H ₂ O
(Wherein R is any one selected from the group consisting of methyl, ethyl, n-propyl and isopropyl, and Ac is an acetyl group)
A reaction tank 1 in which a reaction is performed;
A reaction tower 5 having a multi-stage tray or packing structure for inducing stripping of the reacted ester compound with alcohol or the like;
A cooling condenser (6) for cooling the azeotropic mixture of the ester compound produced through the reaction tower (5) with water and alcohol, and supplying the cooled azeotrope to the decanter;
A reflux decanter (7) for inducing phase separation of the cooled and condensed by the cooling condenser (6), for removing water and alcohol in the lower part of the phase separation, and for refluxing the upper ester compound and alcohol;
When the concentration of acetic acid is measured to be lower than the target value, the alkali is neutralized by neutralizing the acid in the reaction tank, and the unreacted materials and other impurities are adsorbed to the adsorbent to collect the desired organic solvent And an apparatus (8) for recovering an organic solvent generated after manufacturing a semiconductor and a polyimide film for a flexible display.
The method according to claim 6,
The reflux decanter (7)
The lower water and alcohol are discharged to the outside of the reaction system,
Characterized in that the upper ester compound and the alcohol are refluxed to the upper part of the reaction tower. The apparatus for recovering an organic solvent after the production of a semiconductor and a polyimide film for a flexible display.

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