WO2016093385A1

WO2016093385A1 - Method for recovering polyimide

Info

Publication number: WO2016093385A1
Application number: PCT/KR2014/012090
Authority: WO
Inventors: 조승원; 조승민
Original assignee: 주식회사 엔케이이씨
Priority date: 2014-12-10
Filing date: 2014-12-10
Publication date: 2016-06-16

Abstract

The present invention relates to a method for recovering polyimide, comprising a first hydrolysis step, a first filtration step, a second hydrolysis step, and a second filtration step. The first hydrolysis step hydrolyzes polyimide by reacting 480 to 580 parts by weight of alkali and 3000 to 4000 parts by weight of water, with respect to 1000 parts by weight of polyimide waste material, at 90 to 99 ℃ in a nitrogen atmosphere. The first filtration step removes insoluble material by filtering the product of the first hydrolysis step. The second hydrolysis step concentrates, by heating, a filtrate of the first filtration step, and hydrolyzes the filtrate for 3 to 5 hours in a nitrogen atmosphere. The second filtration step cools and then filters the product of the second hydrolysis step to thereby obtain diamine and dianhydride. Accordingly, the present invention can recover polyimide by recovering diamine and dianhydride, which are raw materials of polyimide, from difficult-to-recycle polyimide waste material, and has an effect of having excellent environment friendliness and economic feasibility.

Description

Polyimide Recovery Method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyimide recovery method, and more particularly, to a method capable of recovering a raw material of polyimide from a polyimide waste product which is difficult to recycle.

In general, polyimide molded products and processed waste materials are excellent in chemical resistance, do not dissolve in solvents, and are often non-thermoplastic, and thus cannot be dissolved and recycled like ordinary thermoplastics.

Insoluble and infusible properties are the reason why polyimide is used in many industrial products.However, it is difficult to reclaim or re-use used or defective products. have.

Such landfill disposal needs to secure landfill sites, incinerators are required for disposal of incineration, and environmental impacts are great. In particular, with the problems of resource depletion and global environmental pollution, the demand for recovery technology to recycle waste materials is increasing.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a polyimide recovery method for recovering a raw material of polyimide from polyimide processing waste material having insoluble and insoluble characteristics. have.

Polyimide recovery method according to the present invention for achieving the above object is a polyimide by reacting in a nitrogen atmosphere at 480 to 580 parts by weight of alkali, 3000 to 4000 parts by weight of water at 90 to 99 degrees with respect to 1000 parts by weight of polyimide waste materials The first hydrolysis step for hydrolysis, the first filtration step for filtering the product of the first hydrolysis step to remove insolubles, and the filtrate of the first filtration step is concentrated by heating, 3 to 5 in a nitrogen atmosphere A second hydrolysis step of hydrolyzing for a time and a second filtration step of cooling and filtering the product of the second hydrolysis step to obtain diamine and dianhydride.

In the second filtration step, the precipitate may be washed with deionized water and dried at 90 to 120 ° C. for 20 to 24 hours to afford diamine.

In the second filtration step, an acidity adjustment step of adjusting the pH of the filtrate to 1 to 2, a heating step of maintaining the filtrate through the acidity adjustment step at 90 to 100 degrees for 3 to 5 hours, and a filtration through the heating step Through a cooling step of cooling the liquid to form a precipitate, a third filtration step of filtering the precipitate passed through the cooling step, a washing step of washing the precipitate through the third filtration step, and a drying step of drying the washed precipitate Dianehydrides can be obtained.

The obtained dianhydride can be recrystallized with an acetic anhydride solvent so that the difference between endotherm initiation temperature and endothermic peak temperature may be within 20 degreeC.

Polyimide recovery method according to the present invention for achieving the above object may further comprise a polymerization step of obtaining a polyimide by condensation diamine and dianhydride at 0 to 80 ℃ dehydration ring.

According to the polyimide recovery method according to the present invention, polyimide can be recovered by recovering diamine and dianhydride, which are raw materials of polyimide, from waste polyimide materials. It can be effective.

According to the polyimide recovery method according to the present invention, since the waste can be recycled, there is an effect of excellent environmental friendliness and economy.

1 is a flowchart showing a polyimide recovery method according to an embodiment of the present invention.

FIG. 2 is a flow chart showing a subsequent process for the filtrate of the second filtration step of FIG.

3 is an NMR spectrum of a polyimide raw material recovered by the polyimide recovery method according to the embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. At this time, it is noted that the same components in the accompanying drawings are represented by the same reference numerals as possible. In addition, detailed descriptions of well-known functions and configurations that may blur the gist of the present invention will be omitted. For the same reason, in the accompanying drawings, some components are exaggerated, omitted or schematically illustrated.

1 is a flowchart showing a method for recovering polyimide according to an embodiment of the present invention.

As shown, includes a first hydrolysis step (S100), a first filtration step (S200), a second hydrolysis step (S300), and a second filtration step (S400) according to an embodiment of the present invention. do.

In the first hydrolysis step (S100), the polyimide waste material is hydrolyzed. The polyimide to be decomposed is preferably a waste of polyimide having a definite chemical structure. For example, a defective product that is out of standard in the manufacturing process of a resin molded article, waste water, etc. in the film manufacturing process is easy to calculate the amount of alkali required for hydrolysis due to a clear chemical structure, and the amount of alkali is added as little as possible. It is preferable because it becomes possible.

In general, during the hydrolysis reaction, the amount of alkali is gradually consumed as the reaction proceeds. As a result, the concentration of alkali gradually decreases over time, resulting in a slow reaction. In order to solve this, it may be considered to increase the amount of alkali introduced or decrease the amount of water introduced, which adds to the burden of the subsequent treatment process and becomes difficult to dissolve the electricity, thereby increasing the recovery cost. Polyimide recovery method according to an embodiment of the present invention can further include a second hydrolysis step (S300) to be described later by performing the hydrolysis step by step to reduce the alkali input amount, it is possible to maintain the input amount of water. More specifically, in the first hydrolysis step (S100), polyimide is made by reacting 480 to 580 parts by weight of alkali and 3000 to 4000 parts by weight of water at 90 to 99 degrees with respect to 1000 parts by weight of polyimide waste material. It is preferable to hydrolyze When hydrolysis is performed at a temperature of less than 90 degrees, the time required for decomposition becomes too long, which is not preferable from the viewpoint of productivity, and when hydrolysis is performed at temperatures exceeding 99 degrees, a container having a high internal pressure is required. In some cases, the added alkali may evaporate, which is undesirable.

The alkali to be added is preferably at least one selected from sodium hydroxide or potassium hydroxide, but is not limited thereto. When alkali is added in an amount of less than 480 parts by weight with respect to 1000 parts by weight of polyimide, the hydrolysis takes a long time, which is not preferable in view of productivity. When alkali is added in an amount exceeding 580 parts by weight with respect to 1000 parts by weight of polyimide, it is not preferable because not only the amount of acid for neutralization is increased after decomposition but also impurities in the final product are increased. In addition, the addition of excess alkali is uneconomical, and may cause problems such as inhibition of temperature rise in the reaction system or corrosion of the reactor.

The water to be added is not particularly limited, but preferably, purified water such as distilled water or ion-exchanged water is preferable because of less impurities. For example, it is preferable to use soft water having a small content of ions rather than hard water having a large amount of ions such as calcium or magnesium.

Since the reaction in a nitrogen atmosphere prevents oxidation, the final product may have a purity of 99% or more, a recovery rate of 90% or more, and yellowness. Nitrogen is continuously added, and the amount of nitrogen introduced is preferably 20 to 50 times / hour of the reactor volume.

In the first filtration step (S200) is filtered the product of the first hydrolysis step (S100). This results in a filtrate from which insoluble matters which have not been dissolved are removed. Insoluble matters may include undigested substances and other impurities and may be continuously introduced into the first hydrolysis step S100. Nitrogen is continuously added because it is a continuous process from the first hydrolysis step (S100), and the amount of nitrogen added is preferably 20 to 50 times / hour of the reactor volume because the purity and recovery rate of the final product can be improved.

In the second hydrolysis step (S300), the filtrate of the first filtration step (S200) is concentrated by heating and boiling, and hydrolyzed for 3 to 5 hours in a nitrogen atmosphere. A considerable amount of impurities may be removed when the filtrate is boiling, the amount of evaporation of water due to concentration may be 25 to 67% of the water introduced in the first hydrolysis step (S100). Hydrolysis is carried out while the concentrated filtrate is continuously heated, where hydrolysis is carried out with a reflux condenser, thereby minimizing the loss to steam to increase yield. In the polyimide recovery method according to an embodiment of the present invention, the initial amount of alkali may be small by performing hydrolysis step by step in this manner. In addition, since the whole process is reacted in a nitrogen atmosphere, unnecessary oxidation may be prevented, so that the recovery may be 90% or more and the purity of the obtained product may be 99% or more. The yellowness of the obtained is thus very low. Nitrogen is continuously added, and the amount of nitrogen introduced is preferably 20 to 50 times / hour of the reactor volume.

In the second filtration step (S400), the product of the second hydrolysis step (S300) is cooled and then filtered to obtain diamine and tetracarboxylic acid. The obtained tetracarboxylic acid can be dehydrated by heating to obtain dianhydride.

Diamine (diamine) is obtained by separating the precipitate of the second filtration step (S400), washed with deionized water and dried at 90 to 120 ℃ 20 to 24 hours. The diamine obtained is 1,1,3,3-tetramethyl-1,3-bis (4-aminophenyl) disiloxane, 1,1,3,3-tetraphenoxy-1,3-bis (4-amino Ethyl) disiloxane, 1,1,3,3-tetraphenyl-1,3-bis (2-aminoethyl) disiloxane, 1,1,3,3-tetraphenyl-1,3-bis (3-amino Propyl) disiloxane, 1,1,3,3-tetramethyl-1,3-bis (2-aminoethyl) disiloxane, 1,1,3,3-tetramethyl-1,3-bis (3-amino Propyl) disiloxane, 1,1,3,3-tetramethyl-1,3-bis (3-aminobutyl) disiloxane, 1,3-dimethyl-1,3-dimethoxy-1,3-bis (4 -Aminobutyl) disiloxane, 1,1,3,3,5,5-hexamethyl-1,5-bis (4-aminophenyl) trisiloxane, 1,1,5,5-tetraphenyl-3,3 -Dimethyl-1,5-bis (3-aminopropyl) trisiloxane, 1,1,5,5-tetraphenyl-3,3-dimethoxy-1,5-bis (4-aminobutyl) trisiloxane, 1 , 1,5,5-tetraphenyl-3,3-dimethoxy-1,5-bis (5-aminopentyl) trisiloxane, 1,1,5,5-tetramethyl-3,3-dimethoxy-1 , 5-bis (2-aminoethyl) trisiloxane, 1,1 , 5,5-tetramethyl-3,3-dimethoxy-1,5-bis (4-aminobutyl) trisiloxane, 1,1,5,5-tetramethyl-3,3-dimethoxy-1,5 Bis (5-aminopentyl) trisiloxane, 1,1,3,3,5,5-hexamethyl-1,5-bis (3-aminopropyl) trisiloxane, 1,1,3,3,5, 5-hexaethyl-1,5-bis (3-aminopropyl) trisiloxane, 1,1,3,3,5,5-hexapropyl-1,5-bis (3-aminopropyl) trisiloxane, o- Phenylenediamine, m-phenylenediamine, p-phenylenediamine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3 , 3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethermethane, bis (4-amino-3,5-dimethylphenyl) methane, bis ( 4-amino-3,5-diisopropylphenyl) methane, 3,3'-diaminodiphenyldifluoromethane, 3,4'-diaminodiphenyldifluoromethane, 4,4'-diamino Diphenyldifluoromethane, 3,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone , 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfide, 3,4'-diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfide, 3, 3'-diaminodiphenyl ketone, 3,4'-diaminodiphenyl ketone, 4,4'-diaminodiphenyl ketone, 2,2-bis (3-aminophenyl) propane, 2,2 '-( 3,4'-diaminodiphenyl) propane, 2,2-bis (4-aminophenyl) propane, 2,2-bis (3-aminophenyl) hexafluoropropane, 2,2- (3,4 ' -Diaminodiphenyl) hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (3-amino Phenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 3,3 '-(1,4-phenylenebis (1-methylethylidene)) bisaniline, 3,4'-( 1,4-phenylenebis (1-methylethylidene)) bisaniline, 4,4 '-(1,4-phenylenebis (1-methylethylidene)) bisaniline, 2,2-bis ( 4- (3-aminophenoxy) phenyl) propane, 2,2-bis (4- (3-aminophenoxy) phenyl) hexafluoropropane, 2,2-bis ( 4- (4-aminophenoxy) phenyl) hexafluoropropane, bis (4- (3-aminophenoxy) phenyl) sulfide, bis (4- (4-aminophenoxy) phenyl) sulfide, bis ( 4- (3-aminophenoxy) phenyl) sulfone, bis (4- (4-aminophenoxy) phenyl) sulfone, 1,3-bis (aminomethyl) cyclohexane and 2,2-bis (4-aminophenoxy At least one of ciphenyl) propane and aminophenyl ether.

The dianhydride (dianhydride) is separated from the filtrate of the second filtration step (S400) to adjust the pH to 1 to 2, and heated for 3 to 5 hours to maintain a temperature of 90 to 100 degrees, then cooled and filtered It can be obtained by washing, drying and dehydrating the precipitate. More specifically, the obtained dianhydride is pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3 -Dicarboxyphenyl) propane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, bis (2,3 Dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 3,4,9,10-perylenetetracarboxylic Acid dianhydrides, bis (3,4-dicarboxyphenyl) ether dianhydrides, benzene-1,2,3,4-tetracarboxylic dianhydrides, 3,4,3 ', 4'-benzophenonetetracarboxylic dianhydrides, Benzophenone tetracarboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic Acid dianhydrides, 1,2,4,5-nap Talenetetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2 , 3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, phenanthsene-1,8,9,10-tetracarboxylic dianhydride, pyrazine-2,3,5, 6-tetracarboxylic dianhydride, thiophene-2,3,5,6-tetracarboxylic dianhydride, 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride, 3,4,3', 4'-biphenyltetracarboxylic dianhydride, 2,3,2 ', 3'-biphenyltetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) dimethylsilane dianhydride, bis (3,4- Dicarboxyphenyl) methylphenylsilane dianhydride, bis (3,4-dicarboxyphenyl) diphenylsilane dianhydride, 1,4-bis (3,4-dicarboxyphenyldimethylsilyl) benzene dianhydride, 1,3-bis (3,4-dicarboxyphenyl) -1,1,3,3-tetramethyldicyclohexane dianhydride, p-phenylenebis (t Meritate anhydride), ethylene tetracarboxylic dianhydride, diphenyl ether tetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, tetrahydronaphthalene-1,4,5,8-tetracar Acid dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, cyclopentane-1,2,3,4 Tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, bis (exo-bicyclo [2, 2,1] heptane-2,3-dicarboxylic dianhydride, bicyclo [2,2,2] -octo-7-ene-2,3,5,6-tetracarboxylic dianhydride, 2,2- Bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis [4- (3,4-dicarboxyphenyl) phenyl] propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl Hexafluoropropane dianhydride, 2,2-bis [4- (3,4-dicarboxyphenyl) phenyl] hexafluoropropane dianhydride, 4,4'- S (3,4-dicarboxyphenoxy) diphenylsulfide dianhydride, 1,4-bis (2-hydroxyhexafluoroisopropyl) benzenebis (trimeric acid anhydride), 1,3-bis (2- Hydroxyhexafluoroisopropyl) benzenebis (trimeric anhydride), 5- (2,5-dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, And tetrahydrofuran-2,3,4,5-tetracarboxylic dianhydride.

On the other hand, the polyimide recovery method according to an embodiment of the present invention may further include a polymerization step (S500). In the polymerization step (S500), a polyimide by dehydration ring closure can be obtained by adding diamine and dianhydride obtained in the second filtration step (S400) to an organic solvent and continuously stirring at 0 to 80 ° C for 1 to 10 hours. have. At this time, the organic solvent used is N-methyl-2-pyrrolidinone, N-acetyl-2-pyrrolidinone, N, N-dimethylformamide, N, N-diethylformamide, N, N- It may be at least one selected from dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoamide, diethylene glycol dimethyl ether, and may further contain a ring closure catalyst and a dehydrating agent.

FIG. 2 is a flowchart illustrating a subsequent process for the filtrate of the second filtration step S400 of FIG. 1.

As shown, dianhydride is separated from the filtrate of the second filtration step (S400), acidity adjustment step (S410), heating step (S420), cooling step (S430), the third filtration step ( S440), a washing step (S450) and a drying step (S460) can be obtained through a subsequent process further.

In the acidity adjusting step S410, the pH of the filtrate filtered in the second filtration step S400 is adjusted to 1 to 2. The acid introduced for acidity adjustment is preferably at least one selected from sulfuric acid or hydrochloric acid, but is not limited thereto. In this case, when using hydrochloric acid for acidity adjustment, sodium chloride or potassium hydroxide is added as alkali in the first hydrolysis step (S100), so that sodium chloride is added to the final product. Impurities such as sodium chloride and potassium chloride may be included. In this case, in the drying step (S460) described later, the dianhydride is dissolved and extracted in at least one solvent selected from water, ethanol, DMAC (dimethylacetamide), and NMP (n-methylpyrrolidone) to remove impurities. It is desirable to.

In the heating step (S420) the filtrate passed through the acidity adjustment step (S410) is maintained at 90 to 100 ℃ for 3 to 5 hours. The filtrate is further concentrated through the heating step (S420). When heated to a temperature of less than 90 ℃ less evaporation of impurities may reduce the purity of the final product, it is not preferable in terms of efficiency because the throughput is large when the cooling and filtration afterwards. Heating to a temperature above 100 ° C. is undesirable since the recovery of the final product may drop.

In the cooling step (S430) to cool the filtrate passed through the heating step (S420). As cooling proceeds, a precipitate forms.

In the third filtration step (S440), the precipitate passed through the cooling step (S430) is filtered. The filtered precipitate may be further subjected to the washing step (S450) and the drying step (S460) to be described later, thereby further increasing the purity.

In the washing step (S450) to wash the precipitate passed through the third filtration step (S440). It is preferable to use ion-exchanged water for the washing in view of purity.

In the drying step (S460) to dry the precipitate washed in the washing step (S450). A dianhydride can be obtained by heating and drying dehydrated tetracarboxylic acid. The obtained dianhydride can be improved in purity by recrystallization with an acetic anhydride solvent. The recrystallization is preferably repeated several times so that the difference between the endothermic initiation temperature of the dianhydride and the endothermic peak temperature is within 20 ° C. to increase the purity of the dianhydride. Accordingly, the recovery rate of dianhydride is 90% or more, the purity is 99% or more, and the yellowness is very low.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited by Examples.

Example 1

1000 g of polyimide waste material synthesized from pyromellitic acid dianhydride and 4,4'-diaminodiphenyl ether was introduced into a reactor, and sodium hydroxide ( sodium hydroxide) 480 g and water 3000 g. Nitrogen passage per hour is 20 times the volume of the reactor and hydrolysis is carried out with the temperature raised to 95 degrees. Filtration removes insolubles and leaves the filtrate. The nitrogen is evaporated to boil by raising the temperature of the filtrate to 100 degrees while boiling the nitrogen per hour by 20 times the volume of the reactor to obtain a concentrate. Reflow hydrolysis was carried out for 4 hours while maintaining the boiling state of the concentrate while maintaining the boiling state of the nitrogen at 20 times the volume of the reactor per hour, and then precipitated by cooling, and the precipitate and the filtrate were separated by filtration.

The precipitate is washed and dried again to obtain 480 g of white 4,4'-diaminodiphenyl ether. Recovery is 91.4%. Purity was measured by liquid chromatography, and the purity was over 99%. (A)

The filtrate is added to sulfuric acid (sulfuric acid) to pH 2, the temperature is raised to 100 degrees and maintained for 3 hours, and then cooled and filtered to separate the precipitate. The precipitate is washed and dried to give 600 g of pyromellitic acid. Recovery is 91.0%. Purity was measured by liquid chromatography, and the purity was over 99%. Pyromellitic acid dianhydride is obtained by heating and dehydrating condensation of pyromellitic acid. Recovery is 90.9%. (B)

Example 2

1000 g of polyimide waste material obtained by synthesizing biphenyltetracarboxylic acid dianhydride and 4,4'-diaminodiphenyl ether was introduced into the reactor. 520 g of sodium hydroxide and 4000 g of water are added. Nitrogen passage per hour is 50 times the volume of the reactor and hydrolysis is carried out at a temperature of up to 95 degrees. Filtration removes insolubles and leaves the filtrate. The nitrogen is evaporated to boil by raising the temperature of the filtrate to 100 degrees while boiling the nitrogen per hour by 20 times the volume of the reactor to obtain a concentrate. The nitrogen flow per hour is 50 times the volume of the reactor, reflux hydrolysis is carried out for 3 hours while maintaining the boiling state of the concentrate, and then precipitated by cooling, and the precipitate and the filtrate are separated by filtration.

The precipitate is washed and dried again to obtain 405 g of white 4,4'-diaminodiphenyl ether. Recovery is 92.7%. (A)

The filtrate is added to sulfuric acid (sulfuric acid) to pH 1, the temperature is raised to 100 degrees and maintained for 3 hours, then cooled and filtered to separate the precipitate. The precipitate is washed and dried to give 655 g of biphenyltetracarboxylic acid. Recovery is 91.0%. Biphenyltetracarboxylic acid dianhydride is obtained by heating and dehydrating condensing biphenyltetracarboxylic acid. Recovery is 90.9%. (B)

Example 3

1000 g of polyimide waste material synthesized from pyromellitic acid dianhydride and 4,4'-diaminodiphenyl ether was introduced into a reactor, and sodium hydroxide ( sodium hydroxide) 580 g and water 3500 g. The amount of nitrogen passage per hour is 40 times the volume of the reactor, and hydrolysis is performed at a temperature of up to 99 degrees. Filtration removes insolubles and leaves the filtrate. With nitrogen passing hourly at 40 times the reactor volume, the temperature of the filtrate is raised to 100 degrees and boiled to evaporate 1500 g of water to obtain a concentrate. The nitrogen flow per hour is 40 times the volume of the reactor, reflux hydrolysis is performed for 3 hours while maintaining the boiling state of the concentrate, and then precipitated by cooling, and the precipitate and the filtrate are separated by filtration.

The precipitate is washed and dried again to give 475 g of white 4,4'-diaminodiphenyl ether. Recovery is 90.5%. (A)

The filtrate is added to sulfuric acid (sulfuric acid) to pH 2, the temperature is raised to 90 degrees and maintained for 5 hours, then cooled and filtered to separate the precipitate. The precipitate is washed and dried to give 600 g of pyromellitic acid. Recovery is 90.8%. Pyromellitic acid dianhydride is obtained by heating and dehydrating condensation of pyromellitic acid. Recovery is 90.7%. (B)

Example 4

1000 g of polyimide waste material synthesized with diphenyl ether tetracarboxylic acid dianhydride and 4,4'-diaminodiphenyl ether was placed in a reactor. 580 g of sodium hydroxide and 3000 g of water are added. The amount of nitrogen passage per hour is 40 times the volume of the reactor, and hydrolysis is performed at a temperature of up to 99 degrees. Filtration removes insolubles and leaves the filtrate. The nitrogen is evaporated to boil by raising the temperature of the filtrate to 100 degrees while boiling the nitrogen per hour by 40 times the volume of the reactor to obtain a concentrate. The nitrogen flow per hour is 40 times the volume of the reactor, reflux hydrolysis is performed for 3 hours while maintaining the boiling state of the concentrate, and then precipitated by cooling, and the precipitate and the filtrate are separated by filtration.

The precipitate is washed and dried to yield 380 g of a white 4,4'-diaminodiphenyl ether. Recovery is 90.3%. (A)

The filtrate is added to sulfuric acid (sulfuric acid) to pH 2, the temperature is raised to 100 degrees and maintained for 3 hours, and then cooled and filtered to separate the precipitate. The precipitate is washed and dried to give 676 g of diphenyl ether tetracarboxylic acid. Recovery is 93.0%. Diphenyl ether tetracarboxylic acid (diphenyl ether tetracarboxylic acid) is obtained by heating and dehydrating condensation to obtain diphenyl ether tetracarboxylic acid dianhydride. Recovery is 92.9%. (B)

Example 5

1000 g of polyimide waste material synthesized with benzophenone tetracarboxylic acid dianhydride and 4,4'-diaminodiphenyl ether was introduced into the reactor. 240 g of sodium hydroxide, 336 g of potassium hydroxide and 4000 g of water are added. The passage of nitrogen per hour is 45 times the volume of the reactor, and hydrolysis is carried out at a temperature of up to 99 degrees. Filtration removes insolubles and leaves the filtrate. The nitrogen is evaporated to boil by raising the temperature of the filtrate to 100 degrees while boiling the nitrogen per hour to 45 times the volume of the reactor to obtain a concentrate. Reflowing hydrolysis (reflux hydrolysis) for 4 hours while maintaining the boiling state of the concentrate while maintaining the boiling state of nitrogen at 45 times the reactor volume, precipitates by cooling, and separates the precipitate and the filtrate through filtration.

The precipitate is washed and dried again to give 476 g of white 4,4'-diaminodiphenyl ether. Recovery is 91.0%. (A)

The filtrate is added to sulfuric acid (sulfuric acid) to pH 1, the temperature is raised to 95 ° C and maintained for 3 hours, then cooled and filtered to separate the precipitate. The precipitate is washed and dried to give 686 g of benzophenone tetracarboxylic acid. Recovery is 93.0%. Benzophenone tetracarboxylic acid dianhydride is obtained by heating and dehydrating condensing benzophenone tetracarboxylic acid. Recovery is 92.9%. (B)

The results of Examples 1 to 5 are shown in Table 1 below.

Table 1

division	Raw material		Decomposition condition			Recovery rate		water
division	A	B	Temperature	Nitrogen input amount / hr	Time (reflux hydrolysis)	A	B	water
Example 1	4,4'-diaminodiphenyl ether	pyromellitic acid dianhydride	95 ℃	Reactor volume 20 times	4 hr	91.4%	90.9%	> 99%
Example 2	4,4'-diaminodiphenyl ether	biphenyltetracarboxylic acid dianhydride	95 ℃	Reactor volume 20 times	3 hr	92.7%	90.9%	-
Example 3	4,4'-diaminodiphenyl ether	pyromellitic acid dianhydride	99 ℃	40 times of reactor volume	3 hr	90.5%	90.7%	-
Example 4	4,4'-diaminodiphenyl ether	diphenyl ether tetracarboxylic acid dianhydride	99 ℃	40 times of reactor volume	3 hr	90.3%	92.9%	-
Example 5	4,4'-diaminodiphenyl ether	benzophenone tetracarboxylic acid dianhydride	99 ℃	45 times the reactor volume	4 hr	91.0%	92.9%	-

The experiment is the result of measuring the spectrum using an NMR apparatus to confirm the material (A) finally obtained in Example 1. As shown, the 1 H NMR spectrum of Material (A) obtained in Example 1 shows hydrogen on the para-disubstituted benzene ring as quartet near 6.4 to 7.0 ppm, with an amine over a broad range near 3.2 to 4.0 ppm The hydrogen peak of the group appears. Accordingly, it can be confirmed that the precipitate washed and dried in Example 1 is 4,4'-diaminodiphenyl ether, which is a para-disubstituted benzene ring having an amine group.

On the other hand, the embodiments of the present invention disclosed in the specification and drawings are merely presented specific examples to easily explain the technical contents of the present invention and help the understanding of the present invention, and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention can be carried out in addition to the embodiments disclosed herein.

Claims

A first hydrolysis step of hydrolyzing the polyimide by reacting 480 to 580 parts by weight of alkali and 3000 to 4000 parts by weight of water at 90 to 99 degrees with respect to 1000 parts by weight of the polyimide waste material,

A first filtration step of filtering the product of the first hydrolysis step to remove insoluble matters,

A second hydrolysis step of heating and concentrating the filtrate of the first filtration step and hydrolyzing for 3 to 5 hours in a nitrogen atmosphere;

And a second filtration step of cooling and filtering the product of the second hydrolysis step to obtain diamine and dianhydride.
The method of claim 1,

In the second filtration step

After cooling the product of the second hydrolysis step, the filtered precipitate is washed with deionized water, and dried at 90 to 120 ℃ 20 to 24 hours to obtain a polyimide, characterized in that the diamine.
The method of claim 1,

In the second filtration step

An acidity adjustment step of adjusting the pH of the filtrate after cooling the product of the second hydrolysis step to 1 to 2;

A heating step of maintaining the acidity-adjusted filtrate at 90 to 100 degrees for 3 to 5 hours;

A cooling step of cooling the filtrate passed through the heating step to form a precipitate;

A third filtration step of filtering the precipitate passed through the cooling step;

A washing step of washing the precipitate through the third filtration step;

Polyanimide recovery method characterized in that to obtain a dianhydride through a subsequent process comprising a drying step of drying the washed precipitate.
The method of claim 3,

The dianhydride is obtained by repeating recrystallization with an acetic anhydride solvent such that the difference between the endothermic onset temperature and the endothermic peak temperature is within 20 ° C.
The method of claim 1,

And condensing the diamine and the dianhydride at 0 to 80 ° C, followed by dehydration and ring closure, to obtain a polyimide.