JP5029222B2 - Decomposition and recovery method of polyimide - Google Patents

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, by using an autoclave or the like, polyimide is allowed to coexist with water or alcohol and decomposed into a low molecular weight body 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. It requires a great deal of energy to Cali removal.

JP 2001-169773 A JP 2002-284924 A JP 2002-256104 A Japanese Patent Laid-Open No. 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. Without any treatment, it is also advantageous for removal of used alkali after treatment, and it is possible to obtain a recovered material with less conductive impurities, and to provide a method for efficiently hydrolyzing and recovering low molecular weight materials. Is.

That is, this invention is based on the following structure.
1. A method for decomposing and recovering polyimide, comprising at least a step of hydrolyzing a polyimide obtained by polycondensation of a diamine and a carboxylic acid in a treatment liquid containing ammonia and water.
2. 1. The method for decomposing and recovering polyimide according to 1., wherein hydrolysis is performed at a temperature exceeding 95 ° C and less than 200 ° C.
3. 1. The main component of polyimide carboxylic acids is pyromellitic acid. ~ 2. Disassembly / recovery method for any polyimide.
4). The main component of polyimide diamines is a diamine having a benzoxazole skeleton. ~ 3. Disassembly / recovery method for any polyimide.
-Ammonia is used so that it may become 2600-5200 equivalent with respect to 1000000 mass parts of polyimides. ~ 4. Disassembly / recovery method for any polyimide.
6). 1. The concentration of polyimide with respect to the treatment liquid is 20% by mass or more. ~ 5. Disassembly / recovery method for any polyimide.

  The polyimide obtained by polycondensation of the diamine and the carboxylic acid of the present invention is hydrolyzed in a treatment liquid containing ammonia and water. In the means for hydrolyzing the low molecular weight and recovering the low molecular weight, special equipment such as a high temperature and high pressure reactor in the prior art and a solvent are not required, and this method is similar to alkali hydroxide. It is practically advantageous in terms of speed without significant energy consumption such as neutralization and washing to remove alkali, and it is possible to recover polyimide low molecular weight materials relatively quickly and relatively easily. It is easy to hydrolyze and recover waste that contains it, and polyimide that has not become a product at the time of production. It is possible a lot of contribution in the problem.

The polyimide in the present invention has various forms, and examples thereof include a film state, a state in which a metal thin film, an inorganic thin film, or a composite thereof is laminated on the film. The polyimide is not particularly limited as long as it is a polyimide obtained by polycondensation of a diamine and a carboxylic acid (tetracarboxylic acid), but preferably an aromatic diamine and an aromatic tetracarboxylic acid. It is a polyimide obtained by a reaction, and more preferably the following aromatic diamines (diamine and imide-bonded diamine derivatives, the same shall apply hereinafter) and aromatic tetracarboxylic acids (acids, dianhydrides and imide-bonded acid derivatives, the same shall apply hereinafter). A preferred example is a combination with), but pyromellitic acid is preferred as the carboxylic acid, and a diamine having a benzoxazole skeleton (structure) is preferred as the diamine.
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 the aromatic diamine 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 the 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 based on polyimide benzoxazole obtained by reacting aromatic diamine having benzoxazole structure with aromatic tetracarboxylic anhydride As examples, the following compounds can be exemplified.

これらの中でも、合成のし易さの観点から、アミノ（アミノフェニル）ベンゾオキサゾールの各異性体が好ましい。ここで、「各異性体」とは、アミノ（アミノフェニル）ベンゾオキサゾールが有する２つアミノ基が配位位置に応じて定められる各異性体である（例；上記「化１」〜「化４」に記載の各化合物）。これらのジアミンは、単独で用いてもよいし、二種以上を併用してもよい。
本発明においては、前記ベンゾオキサゾール構造を有する芳香族ジアミンを７０モル％以上使用することが好ましい。

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.

  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.

  Examples of ammonia in the present invention include, but are not limited to, forms of ammonia gas and aqueous ammonia solution.

In the present invention, the pH of the treatment liquid containing ammonia and water (hereinafter also referred to as ammonia water) is preferably in the range of 8.5 to 13, and the hydrolysis treatment using this treatment liquid exceeds 95 ° C. It is preferable that it is less than 200 degreeC.
If the pH of the ammonia water is less than 8.5, the hydrolysis rate is too slow and there are many problems in practical use. If the pH exceeds 13, the container material at the time of treatment is limited and practical. Often not. If the hydrolysis treatment temperature is also 95 ° C. or less, the hydrolysis rate is too slow and there are many problems in practical use. If it is 200 ° C. or more, pressure resistance and technical problems increase, more preferably aqueous ammonia. The pH of the aqueous solution is in the range of 9.0 to 12, and the hydrolysis treatment using the ammonia water is further performed at a temperature of 98 ° C. or higher and lower than 180 ° C., and further 105 ° C. or higher and lower than 150 ° C. preferable.

The amount of ammonia used in the treatment liquid is preferably used so that ammonia is 2600 to 5200 equivalents relative to 1000000 parts by mass of polyimide, and treatment with a polyimide concentration of 20% by mass or more is preferred.
The upper limit of the concentration of the polyimide with respect to the treatment liquid is preferably 42% by mass, more preferably 33% by mass.
The absolute amount of ammonia 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 ammonia. However, if the amount of ammonia is increased more than necessary, it will be difficult to remove the compound containing ammonia from the finally obtained decomposition product, and it will be recovered. This may interfere with the recycling of decomposed 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 reductant treatment can be applied, but removal of residual ammonia after treatment can be removed out of the system relatively easily by heating. It is superior to conventional alkali use. When conventional alkalis, particularly inorganic alkalis, are used, these alkali components remain in the form of salts and are mixed as impurities in the recovered material. Although it is possible to reduce the salt concentration by washing with water or the like, it is extremely difficult to completely remove the salt concentration. The impurities composed of such conductive salts may hinder the reaction when the recovered low molecular weight compound is reused for polyimide or the like, and deteriorate the electrical characteristics of the obtained polyimide film.

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, more preferably 21% by mass to 65% by mass, and more preferably 24% by mass to 60% by mass with respect to the treatment liquid. It is preferable to do. 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 a process in the present invention, (1) a method in which an open reaction vessel is used and the treatment liquid is heated and stirred under normal pressure and refluxed, and (2) a closed reaction vessel is used under heating and pressure. The method of performing reaction can be illustrated, respectively. The latter is preferable in terms of reaction efficiency, but since the apparatus becomes large, (1) and (2) may be appropriately selected on a practical scale.

  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) ) After adding 223 parts by mass of benzoxazole and 4416 parts by mass of N, N-dimethylacetamide and completely dissolving them, Snowtex DMAC-ST30 (manufactured by Nissan Chemical Industries, Ltd.) 40 in which colloidal silica is dispersed in dimethylacetamide .5 parts by mass (including 8.1 parts by mass of silica) and 217 parts by mass of pyromellitic dianhydride are added and stirred at a reaction temperature of 25 ° C. for 24 hours to obtain a brown and viscous polyamic acid solution a. It was. Ηsp / C of this product was 4.0 dl / g.

[Reference Example 2]
(Preliminary dispersion of inorganic particles)
7.6 parts by weight of amorphous silica spherical particle Seahoster KE-P10 (manufactured by Nippon Shokubai Co., Ltd.), 390 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 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 mass of amorphous silica spherical particles Seahoster KE-P10 (manufactured by Nippon Shokubai Co., Ltd.), 420 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 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. A polyimide film A having a thickness of 38 μm 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. A polyimide film B having a thickness of 38 μm 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. It heat-processed with the profile to cool and obtained the 38 micrometer-thick polyimide film C. The imide bond equivalent of the polyimide film C is approximately 5222 meq / kg.

<Examples 1 to 10, Comparative Examples 1 to 4>
Film scraps produced when the polyimide film A and the polyimide film A were produced were 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, and ammonia, sodium hydroxide, hydrazine, and water were charged so as to have the compositions shown in Tables 1, 2, and 3. The treatment was conducted at the temperature and time shown in FIG. The results are shown in Tables 1 to 3.
In the table, A, B, and C in the polyimide column indicate the amount of film scrap generated when each polyimide film and each polyimide film are produced.
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 having an alkali equivalent of 1.2 times 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 a 5B filter paper to obtain a recovered product. Tables 1 to 3 show the amount of the recovered material obtained.
10 parts by mass of the recovered material obtained was dispersed in 90 parts by mass of deionized water, and the electrical conductivity of the supernatant after standing for 24 hours was evaluated for conductivity of DS-51 manufactured by HORIBA, Ltd. in order to evaluate the amount of electrically conductive impurities. Measured with The results are shown in Tables 1 to 3.
Similarly, the experiment was conducted by changing the amount of film waste generated when producing the polyimide film and the polyimide film, and the amounts of ammonia, sodium hydroxide, hydrazine, and water as shown in Tables 1 to 3. The results are shown in Tables 1 to 3. 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. NaOH represents sodium hydroxide.

  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 quickly and relatively easily recovering a polyimide low-molecular-weight material with less conductive impurities.

Claims (6)

Polyimide obtained by polycondensation of diamines and carboxylic acids is included in a treatment liquid containing ammonia and water, and includes at least a hydrolysis step, and 10 parts by mass of the recovered material is 90 parts by mass of deionized water. A method for decomposing and recovering polyimide, characterized in that the electrical conductivity of the supernatant after dispersion for 24 hours and measuring the electrical conductivity of the supernatant is 0.010 mS or less .   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, 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 ammonia is used so as to be less than 2 equivalents relative to 1 equivalent of imide groups in the polyimide.   The method for decomposing and recovering polyimide according to claim 1, wherein the concentration of the polyimide with respect to the treatment liquid is 20% by mass or more.