JP2008280424A - Method for decomposition and recovery of polyimide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for recovering a polyimide at increased recovery speed without using a particular apparatus by hydrolyzing the polyimide. <P>SOLUTION: The method for the decomposition and recovery of a polyimide comprises the hydrolysis of the polyimide at 95-200°C in a treating liquid containing (A) a water-soluble compound having an amino group in the molecule, (B) at least one of a water-soluble alcohol and (C) water. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for hydrolyzing and recovering polyimide or polyimide-containing waste in industrial waste that has been disposed of in large quantities in recent years, and polyimide that has not been commercialized at the time of production.

Polyimide molded products or films have excellent chemical resistance, are often insoluble in solvents and are non-thermoplastic, and can be melted and reused like thermoplastics such as polystyrene. could not.
These excellent performance polyimides are used in many industrial products, and it is difficult to recycle and recycle used and defective products. It is disposed of by incineration.
Landfill disposal requires land acquisition or incineration requires an incinerator, which has a great impact on the global environment. In particular, since the recent problems of global environmental pollution and resource depletion have been screamed, recovery methods for effective reuse have become an important issue.
In order to solve this problem, chemical recycling means and techniques for chemically decomposing polyimide have been proposed.

For example, using an autoclave or the like, a method in which polyimide is coexisted with water or alcohol and decomposed into a low molecular weight substance under a high temperature and high pressure condition of 110 ° C. or higher and 1 MPa or higher (see Patent Document 1), a member having polyimide resin and water A method of decomposing under a condition of 200 ° C. or higher and 400 ° C. or lower and a saturated water vapor pressure of water or higher in that temperature (see Patent Document 2), a polymer-containing solid such as polyimide having a solubility parameter of 18 (MJ / m ³ ) A method of decomposing the polymer solid by bringing it into contact with a polymer decomposing material containing a solvent having a solubility parameter of ^1/2 or more at a temperature of 200 ° C. or more (see Patent Document 3), Using a highly polar solvent as the polymer decomposing material or using supercritical water or subcritical water, a high temperature of 200 to 700 ° C., and 2 to 100 By keeping under high pressure of Pa, polyimide etc. hydrolyzing (see Patent Document 4) it has been proposed. Since these proposed means require high-temperature and high-pressure conditions, industrial equipment requires special equipment such as high-temperature and high-pressure reactors, so capital investment is expensive and maintenance is required to maintain safety. However, there are many practical problems such as the need for advanced driving skills.

Chemicals used for decomposition and neutralization are not required to use special equipment such as high-temperature and high-pressure reactors or solvents in the means for recovering low-molecular weight by alkali hydrolysis of polyimide. As a method for producing a low molecular weight substance with a small amount of impurities caused by the above and recovering this low molecular weight substance, the amount of polyimide to generate 2 to 80 times moles of hydroxide ions (OH ⁻ ) per mole of imide groups A method of alkali hydrolysis of polyimide that decomposes into a low molecular weight product by alkaline hydrolysis in the presence of a basic substance (see Patent Document 5) has also been proposed. It has been known since ancient times and often has practical problems from the viewpoint of decomposition rate.

JP 2001-169773 A JP 2002-284924 A JP 2002-256104 A JP-A-10-287766 JP 2006-124530 A

  The present invention does not require special equipment such as a high-capacity high-temperature and high-pressure reaction vessel, advanced operation technology, and is also useful from the viewpoint of decomposition rate, and is used for landfill treatment and incineration of unnecessary polyimide products and polyimide films. It is intended to provide a method for rapidly hydrolyzing and recovering low molecular weight substances without treatment.

That is, this invention is based on the following structure.
1. Treatment comprising a polyimide obtained by polycondensation of diamines and carboxylic acids, (A) a water-soluble compound having an amino group in the molecule, (B) at least one kind of water-soluble alcohol, and (C) water. A method for decomposing and recovering polyimide, comprising at least a step of hydrolyzing in a liquid.
2. The method for decomposing and recovering polyimide according to 1 above, wherein the hydrolysis is performed at a temperature exceeding 95 ° C and less than 200 ° C.
3. The method for decomposing / recovering a polyimide according to either 1 or 2 above, wherein the main component of the carboxylic acid of the polyimide is pyromellitic acid.
4). The method for decomposing / recovering a polyimide according to any one of 1 to 3 above, wherein the main component of the diamines of the polyimide is a diamine having a benzoxazole skeleton.
5. (A) The method for decomposing / recovering a polyimide according to any one of (1) to (4) above, wherein a water-soluble compound having an amino group in the molecule is used so that the amino group is 2600 to 5200 equivalents relative to 1000000 parts by mass of the polyimide.
6). The method for decomposing / recovering polyimide according to any one of 1 to 5 above, wherein the polyimide concentration in water is 20% by mass or more.

  Polyimide obtained by polycondensation of diamines of the present invention and carboxylic acids, (A) a water-soluble compound having an amino group in the molecule, (B) at least one kind of water-soluble alcohol, (C) water According to the method for decomposing and recovering the polyimide to be hydrolyzed in the treatment liquid containing, as described below, in the means for hydrolyzing the polyimide into a low molecular weight and recovering this low molecular weight, Special equipment such as a high-temperature and high-pressure-resistant reaction vessel and a solvent are unnecessary, which is practically advantageous in terms of speed, and allows the polyimide low molecular weight substance to be recovered quickly and relatively easily.

Polyimides in the present invention have various forms, and polyimides whose examples include film states, metal thin films, inorganic thin films, and composites laminated on the films are diamines and carboxylic acids. Although it will not specifically limit if it is a polyimide obtained by polycondensation with (tetracarboxylic acids), Preferably it is a polyimide obtained by reaction with aromatic diamines and aromatic tetracarboxylic acids, and more Preferred combinations of the following aromatic diamines (diamines and imide-bonded diamine derivatives, hereinafter the same) and aromatic tetracarboxylic acids (acids, dianhydrides and imide-bonded acid derivatives, the same below) are preferred examples. As the carboxylic acid, pyromellitic acid is preferable, and as the diamine, Diamines having oxazole skeleton (structure) are preferred.
A. A combination of an aromatic diamine having a benzoxazole structure and an aromatic tetracarboxylic acid.
B. A combination of an aromatic diamine having a diaminodiphenyl ether skeleton and an aromatic tetracarboxylic acid having a pyromellitic acid skeleton.
C. A combination of an aromatic diamine having a phenylenediamine skeleton and an aromatic tetracarboxylic acid having a pyromellitic acid skeleton.
D. A combination of an aromatic diamine having a phenylenediamine skeleton and an aromatic tetracarboxylic acid having a biphenyltetracarboxylic acid skeleton.
Moreover, the combination of 1 or more types of said ABCD is preferable.

These aromatic diamines and aromatic tetracarboxylic acids constitute imide bonds as respective residues in polyimide (film).
Examples of aromatic diamines having a diaminodiphenyl ether skeleton that can be preferably used in the present invention include 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, and 3,4′-diaminodiphenyl ether. In particular, 4,4′-diaminodiphenyl ethers can be preferably used, and 70 mol% or more can be used in the polyimide of each of the above examples in the present invention. preferable.
Examples of phenylenediamines include p-phenylenediamine, o-phenylenediamine, and m-phenylenediamine. Among them, p-phenylenediamine can be preferably used. It is preferable to use the above.
Aromatic diamine having benzoxazole structure used for polyimide benzoxazole mainly composed of polyimide benzoxazole obtained by reacting aromatic diamine having benzoxazole structure with aromatic tetracarboxylic anhydrides As examples, the following compounds can be exemplified.

Among these, amino (aminophenyl) benzoxazole isomers are preferable from the viewpoint of ease of synthesis. Here, “each isomer” refers to each isomer in which two amino groups of amino (aminophenyl) benzoxazole are determined according to the coordination position (eg, the above “formula 1” to “formula 4”). Each compound described in the above. These diamines may be used alone or in combination of two or more.
In the present invention, it is preferable to use 70 mol% or more of the aromatic diamine having the benzoxazole structure.

The present invention is not limited to the above matters, and the following aromatic diamines may be used, but preferably the benzoxazole structure exemplified below is not provided as long as it is less than 30 mol% of the total aromatic diamines. It is a polyimide film in which one or more diamines are used in combination (A. In the case of a combination of an aromatic diamine having a benzoxazole structure and an aromatic tetracarboxylic acid).
Similarly, B.I. A combination of an aromatic diamine having a diaminodiphenyl ether skeleton and an aromatic tetracarboxylic acid having a pyromellitic acid skeleton; Even in the case of a combination of an aromatic diamine having a phenylenediamine skeleton and an aromatic tetracarboxylic acid having a biphenyltetracarboxylic acid skeleton, the diamines exemplified below are less than 30 mol% of the total aromatic diamines. Among them, a polyimide film using a combination of materials other than the corresponding diamines may be used.

  Examples of such diamines include 4,4′-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, and bis [4- (3-aminophenoxy) phenyl]. Sulfide, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine,

3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfoxide, 3,4′-diaminodiphenyl sulfoxide 4,4′-diaminodiphenyl sulfoxide, 3,3′-diaminodiphenyl sulfone, 3,4′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfone, 3,3′-diaminobenzophenone, 3,4′- Diaminobenzophenone, 4,4′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, bis [4- (4-aminophenoxy) phenyl] methane, 1 , 1-Bi [4- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-aminophenoxy) phenyl] ethane, 1,1-bis [4- (4-aminophenoxy) phenyl] propane, 1 , 2-bis [4- (4-aminophenoxy) phenyl] propane, 1,3-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl ]propane,

1,1-bis [4- (4-aminophenoxy) phenyl] butane, 1,3-bis [4- (4-aminophenoxy) phenyl] butane, 1,4-bis [4- (4-aminophenoxy) Phenyl] butane, 2,2-bis [4- (4-aminophenoxy) phenyl] butane, 2,3-bis [4- (4-aminophenoxy) phenyl] butane, 2- [4- (4-aminophenoxy) Phenyl] -2- [4- (4-aminophenoxy) -3-methylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3-methylphenyl] propane, 2- [4- ( 4-aminophenoxy) phenyl] -2- [4- (4-aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3,5-dimethylphen Le] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane,

1,4-bis (3-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) ) Biphenyl, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [4- ( 4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,3-bis [4- (4-aminophenoxy) ) Benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,4-bis [4- ( -Aminophenoxy) benzoyl] benzene, 4,4'-bis [(3-aminophenoxy) benzoyl] benzene, 1,1-bis [4- (3-aminophenoxy) phenyl] propane, 1,3-bis [4 -(3-aminophenoxy) phenyl] propane, 3,4'-diaminodiphenyl sulfide,

2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, bis [4- (3-aminophenoxy) phenyl] methane, 1,1 -Bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane, bis [4- (3-aminophenoxy) phenyl] sulfoxide, 4,4 '-Bis [3- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [3- (3-aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [4- (4-amino-α) , Α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, bis 4- {4- (4-aminophenoxy) phenoxy} phenyl] sulfone, 1,4-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-trifluoromethylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3 -Bis [4- (4-amino-6-fluorophenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-methylphenoxy) -α, α-dimethylbenzyl Benzene, 1,3-bis [4- (4-amino-6-cyanophenoxy) -α, α-dimethylbenzyl] benzene,

3,3′-diamino-4,4′-diphenoxybenzophenone, 4,4′-diamino-5,5′-diphenoxybenzophenone, 3,4′-diamino-4,5′-diphenoxybenzophenone, 3, 3'-diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4'-diamino-4-phenoxybenzophenone, 3,4'-diamino-5'-phenoxybenzophenone, 3,3 '-Diamino-4,4'-dibiphenoxybenzophenone, 4,4'-diamino-5,5'-dibiphenoxybenzophenone, 3,4'-diamino-4,5'-dibiphenoxybenzophenone, 3,3'- Diamino-4-biphenoxybenzophenone, 4,4′-diamino-5-biphenoxybenzophenone, 3,4 -Diamino-4-biphenoxybenzophenone, 3,4'-diamino-5'-biphenoxybenzophenone, 1,3-bis (3-amino-4-phenoxybenzoyl) benzene, 1,4-bis (3-amino- 4-phenoxybenzoyl) benzene, 1,3-bis (4-amino-5-phenoxybenzoyl) benzene, 1,4-bis (4-amino-5-phenoxybenzoyl) benzene, 1,3-bis (3-amino) -4-biphenoxybenzoyl) benzene, 1,4-bis (3-amino-4-biphenoxybenzoyl) benzene, 1,3-bis (4-amino-5-biphenoxybenzoyl) benzene, 1,4-bis (4-Amino-5-biphenoxybenzoyl) benzene, 2,6-bis [4- (4-amino-α, α-dimethylbenzyl) pheno Si] benzonitrile and some or all of the hydrogen atoms on the aromatic ring in the aromatic diamine are halogen atoms, alkyl groups having 1 to 3 carbon atoms or alkoxyl groups, cyano groups, or alkyl groups or alkoxyl group hydrogen atoms. Examples thereof include aromatic diamines substituted with a halogenated alkyl group having 1 to 3 carbon atoms partially or wholly substituted with a halogen atom or an alkoxyl group.

  The aromatic tetracarboxylic acids used in the present invention are, for example, aromatic tetracarboxylic anhydrides. Specific examples of the aromatic tetracarboxylic acid anhydrides include the following, but it is preferable to use 70 mol% or more in polyimide, and it is particularly preferable to use 70 mol% or more of pyromellitic acid. preferable.

These tetracarboxylic dianhydrides may be used alone or in combination of two or more.
In the present invention, as long as it is less than 30 mol% of the total tetracarboxylic dianhydrides, one or more of the non-aromatic tetracarboxylic dianhydrides exemplified below are used in combination regardless of the above-mentioned limitations. It doesn't matter. Examples of such tetracarboxylic acid anhydrides include butane-1,2,3,4-tetracarboxylic dianhydride, pentane-1,2,4,5-tetracarboxylic dianhydride, and cyclobutanetetracarboxylic acid. Acid dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, cyclohex-1-ene-2,3 5,6-tetracarboxylic dianhydride, 3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohexane-3 -(1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride 1-ethylcyclohexane -(1,2), 3,4-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-dipropylcyclohexane- 1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride,

Bicyclo [2.2.1] heptane-2,3,5,6-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1 , 3-Dipropylcyclohexane-1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride, bicyclo [2.2.1] Heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and the like. These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  The solvent used when the polyamic acid is obtained by reacting (polymerizing) the aromatic diamine and the aromatic tetracarboxylic acid (anhydride) dissolves both the monomer as a raw material and the polyamic acid to be produced. Although it will not specifically limit if it is a thing, A polar organic solvent is preferable, for example, N-methyl- 2-pyrrolidone, N-acetyl- 2-pyrrolidone, N, N- dimethylformamide, N, N- diethylformamide, N, N -Dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoric amide, ethyl cellosolve acetate, diethylene glycol dimethyl ether, sulfolane, halogenated phenols and the like. These solvents can be used alone or in combination. The amount of the solvent used may be an amount sufficient to dissolve the monomer as a raw material. As a specific amount used, the mass of the monomer in the solution in which the monomer is dissolved is usually 5 to 40% by mass, The amount is preferably 10 to 30% by mass.

The polymerization reaction conditions for obtaining the polyamic acid may be conventionally known conditions. As a specific example, stirring and / or continuous in an organic solvent at a temperature range of 0 to 80 ° C. for 10 minutes to 30 hours. Mixing may be mentioned. If necessary, the polymerization reaction may be divided or the temperature may be increased or decreased. In this case, the order of adding both monomers is not particularly limited, but it is preferable to add aromatic tetracarboxylic acid anhydrides to the solution of aromatic diamines. The mass of the polyamic acid in the polyamic acid solution obtained by the polymerization reaction is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and the viscosity of the solution is measured with a Brookfield viscometer (25 ° C.). From the viewpoint of the stability of liquid feeding, it is preferably 10 to 2000 Pa · s, and more preferably 100 to 1000 Pa · s. The reduced viscosity (ηsp / C) of the polyamic acid in the present invention is not particularly limited, but is preferably 2.0 dl / g or more, and more preferably 3.0 dl / g or more.
Vacuum defoaming during the polymerization reaction is effective for producing a high-quality polyamic acid organic solvent solution. Moreover, you may perform superposition | polymerization by adding a small amount of terminal blockers to aromatic diamines before a polymerization reaction. Examples of the end capping agent include compounds having a carbon-carbon double bond such as maleic anhydride. The amount of maleic anhydride used is preferably 0.001 to 1.0 mol per mol of aromatic diamine.

As an imidization method by high-temperature treatment, a conventionally known imidation reaction can be appropriately used. For example, using a polyamic acid solution that does not contain a ring-closing catalyst or a dehydrating agent, the imidization reaction proceeds by subjecting it to a heat treatment (so-called thermal ring-closing method), or the polyamic acid solution contains a ring-closing catalyst and a dehydrating agent. In particular, a chemical ring closing method in which an imidization reaction is performed by the action of the above ring closing catalyst and a dehydrating agent can be given.
In the chemical ring closure method, imidation can be completely performed by heating after forming a precursor complex having self-supporting property by partially proceeding imidization reaction of the polyamic acid solution.
In this case, the condition for partially proceeding with the imidization reaction is preferably a heat treatment for 3 to 20 minutes at 100 to 200 ° C., and the condition for allowing the imidization reaction to be completely performed is preferably 200 to 400 ° C. For 3 to 20 minutes.

In the present invention, (A) the water-soluble compound having an amino group in the molecule is not particularly limited as long as it is alkaline and has (decomposition) solubility of polyimide. For example, monoethanolamine , Ethanolamine, propanolamine, butanolamine, diethanolamine, dipropanolamine, hydrazine monohydrate, ethylenediamine, dimethylamine and the like.
Examples of the water-soluble alcohol (B) in the present invention include ethylene glycol, diethylene glycol, triethylene glycol, glycerin, ethylene glycol methyl cellosolve, ethylene glycol ethyl cellosolve, ethylene glycol, diethylene glycol, triethylene glycol, glycerin esters and amino derivatives. And sulfonic acid derivatives.
The above-mentioned (A) water-soluble compound having an amino group in the molecule and (B) water-soluble alcohol should be present together in alkaline water, taking into consideration the ease of decomposition of the partner polyimide. Can be selected and used as appropriate. In addition to these, alkaline substances such as sodium hydroxide, potassium hydroxide, and ammonium hydroxide may be appropriately added and used.
(C) About water, it is preferable to use pure water or ion-exchanged water.

  In the present invention, (A) the water-soluble compound having an amino group in the molecule, (B) the pH of the alkaline water in which the water-soluble alcohol is dissolved is preferably in the range of 8.5 to 12, and the alkaline water is used. The hydrolysis treatment is preferably performed at a temperature of 95 to 200 ° C. If the pH of the alkaline water is less than 8.5, the hydrolysis rate is too slow and there are many problems in practical use. If the pH exceeds 12, the material for the container at the time of processing is limited and practical. Absent. If the hydrolysis treatment temperature is also less than 95 ° C, the hydrolysis rate is too slow and there are many problems in practical use. If it exceeds 160 ° C, pressure resistance and technical problems increase, more preferably alkaline water. The pH of is in the range of 9.0-11, and the hydrolysis treatment using alkaline water is at a temperature of 95-125 ° C.

It is preferable to use a water-soluble compound having an amino group in the molecule so that the amino group is 2600 to 5200 equivalents relative to 1000000 parts by mass of polyimide, and a treatment in which the concentration of polyimide with respect to water is 20% by mass or more is preferable. .
The absolute amount of amino groups in the treatment liquid is preferably suppressed to less than 2 equivalents with respect to 1 equivalent of imide groups in the polyimide to be treated. It is possible to increase the decomposition rate by increasing the amount of amino groups, but if the amount of amino groups is increased more than necessary, it will be difficult to remove the compound containing the amino group from the finally obtained decomposition product. In some cases, it may interfere with the recycling of the collected decomposition products. In addition, there may be a problem in the corrosion resistance of the processing container or the like, and there may be a problem in industrialization, for example, a facility using an unnecessarily expensive corrosion resistant material.

  In the present invention, the polyimide to be decomposed is refined by cutting or pulverizing, the low-molecular substances are recovered from the hydrolyzed polyimide, the undecomposed product is filtered, the precipitate is separated by adding an acidic aqueous solution, the crystal Conventional techniques such as precipitation, ion exchange treatment, activated carbon treatment, oxidant treatment, and reducing agent treatment can be applied.

When processing a polyimide film in the present invention, it is preferable to process the polyimide film by slicing, more preferably, the average size of the strips is 30 mm or less, more preferably 10 mm or less, more preferably about 4 mm or less. It is better to break it up into pieces. If the strip size is too large, it may interfere with stirring and transportation in the treatment tank.
The treatment amount of the polyimide film in the present invention is preferably 20% by mass to 70% by mass with respect to water, more preferably 21% by mass to 65% by mass, and more preferably 24% by mass to 60% by mass. It is preferable. If the processing amount is less than this range, the processing efficiency is deteriorated. When the processing amount exceeds this range, the fluidity after processing deteriorates, which may impede the collection work.

As the acidic aqueous solution, an aqueous solution containing an inorganic acid having a concentration of 0.01 to 10 M is preferably applicable. As the inorganic acid, these acids including hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid and the like may be appropriately selected and used.
Organic acids such as acetic acid, succinic acid, and citric acid may be used, and these organic acids may be used in combination with the aqueous solution of the inorganic acid.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited by a following example. In addition, the evaluation method of the physical property in the following examples is as follows.
1. Reduced viscosity of polyamic acid (ηsp / C)
A solution dissolved in N-methyl-2-pyrrolidone (or N, N-dimethylacetamide) so that the polymer concentration was 0.2 g / dl was measured at 30 ° C. with an Ubbelohde type viscosity tube. (When the solvent used for preparing the polyamic acid solution was N, N-dimethylacetamide, the polymer was dissolved using N, N-dimethylacetamide and measured.)

2. The thickness of the polyimide film The thickness was measured using a micrometer (Millitron 1254D manufactured by Fine Reef).

[Reference Example 1]
Nitrogen introduction tube, thermometer, vessel wetted part equipped with stirring rod, and infusion pipe were replaced with nitrogen in the reaction vessel of austenitic stainless steel SUS316L, and then 5-amino-2- (p-aminophenyl) ) Snowtex DMAC-ST30 (manufactured by Nissan Chemical Industries, Ltd.) 40, in which 223 parts by mass of benzoxazole and 4416 parts by mass of N, N-dimethylacetamide were completely dissolved and then colloidal silica was dispersed in dimethylacetamide. .5 parts by mass (including 8.1 parts by mass of silica) and 217 parts by mass of pyromellitic dianhydride were added and stirred for 24 hours at a reaction temperature of 25 ° C. to obtain a brown and viscous polyamic acid solution a. . The reduced viscosity (ηsp / C) was 4.0 dl / g.

[Reference Example 2]
(Preliminary dispersion of inorganic particles)
7.6 parts by mass of amorphous silica spherical particles Seahoster KE-P10 (manufactured by Nippon Shokubai Co., Ltd.), 390 parts by mass of N-methyl-2-pyrrolidone, and the infusion part are austenitic stainless steel SUS316L And stirred for 1 minute at a rotation speed of 1000 rpm with a homogenizer T-25 basic (manufactured by IKA Labortechnik) to obtain a preliminary dispersion.
(Preparation of polyamic acid solution)
The liquid contact part of the vessel equipped with a nitrogen introduction tube, a thermometer, a stirring rod, and the pipe for infusion were substituted with nitrogen in the reaction vessel made of austenitic stainless steel SUS316L, and then 200 parts by mass of diaminodiphenyl ether was added. Next, after 3800 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, 390 parts by mass and 217 parts by mass of pyromellitic dianhydride were added to the preliminary dispersion obtained above. When the mixture was stirred at 0 ° C. for 5 hours, a brown viscous polyamic acid solution b was obtained. The reduced viscosity (ηsp / C) was 3.7 dl / g.

[Reference Example 3]
(Preliminary dispersion of inorganic particles)
3.7 parts by weight of amorphous silica spherical particle Seahoster KE-P10 (manufactured by Nippon Shokubai Co., Ltd.), 420 parts by weight of N-methyl-2-pyrrolidone, the liquid contact part of the container, and the infusion pipe are austenitic stainless steel SUS316L And stirred for 1 minute at a rotation speed of 1000 rpm with a homogenizer T-25 basic (manufactured by IKA Labortechnik) to obtain a preliminary dispersion.
(Preparation of polyamic acid solution)
The wetted part of the vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod, and the infusion piping were substituted with nitrogen in the reaction vessel made of austenitic stainless steel SUS316L, and then 108 parts by mass of phenylenediamine was added. Next, after 3600 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, 420 parts by mass and 292.5 parts by mass of biphenyltetracarboxylic dianhydride were added to the preliminary dispersion obtained above. When the mixture was stirred at 25 ° C. for 12 hours, a brown viscous polyamic acid solution c was obtained. The reduced viscosity (ηsp / C) was 4.5 dl / g.

<Film Production Example 1>
The polyamic acid solution a was coated on a stainless steel belt with a squeegee / belt gap of 950 μm and dried at 110 ° C. for 15 minutes. The polyamic acid film that became self-supporting after drying was peeled from the stainless steel belt to obtain a green film. The obtained green film was passed through a continuous heat treatment furnace, the first stage was heat treated at 150 ° C. for 2 minutes, then at 200 ° C. for 2 minutes, and then heat treated at 495 ° C. for 4 minutes to advance the imidization reaction. And polyimide film A was obtained. The imide bond equivalent of the polyimide film A is approximately 5235 meq / kg.

<Film Production Example 2>
The polyamic acid solution b was coated on a stainless steel belt with a squeegee / belt gap of 950 μm and dried at 100 ° C. for 20 minutes. The polyamic acid film that became self-supporting after drying was peeled from the stainless steel belt to obtain a green film. The obtained green film is passed through a continuous heat treatment furnace. The first stage is heat treated at 130 ° C. for 2 minutes, then at 180 ° C. for 2 minutes, and then heat treated at 400 ° C. for 4 minutes to advance the imidization reaction. Polyimide film B was obtained. The imide bond equivalent of the polyimide film B is approximately 5465 meq / kg.

<Film Production Example 3>
The polyamic acid solution c was coated on a stainless steel belt with a squeegee / belt gap of 950 μm and dried at 110 ° C. for 15 minutes. The polyamic acid film that became self-supporting after drying was peeled from the stainless steel belt to obtain a green film. The obtained green film is passed through a continuous heat treatment furnace, heated from 100 ° C. to 450 ° C. at a rate of 50 ° C./min, held at 450 ° C. for 2 minutes, and about 50 ° C. in about 1 minute. A polyimide film C was obtained by heat treatment with a cooling profile. The imide bond equivalent of the polyimide film C is approximately 5222 meq / kg.

<Examples 1 to 21 and Comparative Examples 1 to 7>
Film waste generated when the polyimide film A and the polyimide film A were produced was crushed into strips having an average side length of about 5 mm by a cutting machine. The obtained strip was put into a flask equipped with a stirring blade and a reflux tube. Amino-containing compound, alcohol, and water were charged so that the composition shown in Table 1 was obtained. The treatment was conducted at the temperature and time shown in FIG. The results are shown in Table 1.
In the table, “amino group / polyimide mass” is the ratio of the amino group equivalent of the amino-containing compound to the polyimide mass. In the table, A, B, and C in the polyimide column indicate the amount of film waste generated when producing each polyimide film and each polyimide film.
About "the fluidity | liquidity after a process", the state of the sample after a process is visually determined.
“Undecomposed matter amount” is a solid substance amount part obtained by filtering the treated container contents through a 100-mesh stainless steel mesh and washing and drying the solid matter remaining on the stainless steel mesh.
Hydrochloric acid 1.2 times the amino group equivalent was added to the filtrate obtained by filtration through a stainless steel mesh, and the resulting precipitate was filtered, washed with water and dried with 5B filter paper to obtain a recovered product. The amount of recovered material obtained is shown in Table 1.
Similarly, the experiment was performed by changing the amount of film scrap generated when producing the polyimide film and the polyimide film, the amino-containing compound, the alcohol, and the amount of water as shown in Tables 1 to 4. The results are shown in Tables 1-4. When the processing environment is “sealed” and the temperature condition is 100 ° C. or higher and lower than 125 ° C., use a rotary dyeing tester mini color (manufactured by Tecsum Giken Co., Ltd.). And processed. When the processing temperature was 125 ° C. or higher, the sealed mini-color tester pot was placed in a PCT tester (manufactured by Hirayama Seisakusho) for processing.

表中の略号は以下の通りである。
ＤＥＧＭＥ：ジエチレングリコールモノメチルエーテル
ＭＥＡ：モノエタノールアミン
ＤＥＡ：ジエタノールアミン
ＨＺ：ヒドラジン
ＥＣ：エチルセロソルブ
ＰＯＨ：プロパノール

Abbreviations in the table are as follows.
DEGME: Diethylene glycol monomethyl ether MEA: monoethanolamine DEA: diethanolamine HZ: hydrazine EC: ethyl cellosolve POH: propanol

  The polyimide hydrolysis method of the present invention is a means for hydrolyzing a polyimide into a low molecular weight body and collecting the low molecular weight body, and does not require special equipment such as a high-temperature high-pressure reactor in the prior art or a solvent. Thus, the method is practically advantageous in terms of speed, and is extremely useful as a method capable of recovering a polyimide low molecular weight substance quickly and relatively easily.

Claims (6)

  A treatment comprising a polyimide obtained by polycondensation of a diamine and a carboxylic acid, comprising (A) a water-soluble compound having an amino group in the molecule, (B) at least one kind of water-soluble alcohol, and (C) water. A method for decomposing and recovering polyimide, comprising at least a hydrolysis step in the liquid.   The method for decomposing and recovering polyimide according to claim 1, wherein the hydrolysis step is carried out at a temperature exceeding 95 ° C and less than 200 ° C.   The method for decomposing and recovering polyimide according to claim 1 or 2, wherein the main component of the carboxylic acid of polyimide is pyromellitic acid.   The method for decomposing and recovering polyimide according to any one of claims 1 to 3, wherein a main component of the diamines of polyimide is a diamine having a benzoxazole skeleton.   The method for decomposing and recovering polyimide according to any one of claims 1 to 4, wherein (A) a water-soluble compound having an amino group in the molecule is used so that the amino group is 2600 to 5200 equivalents with respect to 1000000 parts by mass of polyimide. .   The method for decomposing and recovering polyimide according to any one of claims 1 to 5, wherein the concentration of polyimide with respect to water is 20% by mass or more.