JPH0820664A - Method for producing aromatic dicarboxylic acid from polyester - Google Patents

Abstract

(57) [Summary] [Purpose] To develop a method for producing aromatic dicarboxylic acids free of polyvinyl chloride from polyester waste with high productivity. [Structure] A resin composition composed of a thermoplastic polyester as a main component and polyvinyl chloride as an auxiliary component is hydrolyzed to convert the polyester into an aromatic dicarboxylic acid, and the produced crude aromatic dicarboxylic acid is then converted into an aprotic polar compound. After dissolving in a solvent, the insoluble matter is filtered off to produce an aromatic dicarboxylic acid containing no decomposition product of polyvinyl chloride. [Effect] (Example 10) Recovery rate of terephthalic acid 98.3
%, Purity 99.4%.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a thermoplastic polyester as a main component, for example, polyethylene terephthalate (abbreviation "PET"), polybutylene terephthalate (abbreviation "P").
BT ”) or polyethylene naphthalate (abbreviated as“ PE ”)
N ”) and a chlorine-containing polyalkene as a subcomponent and a component selected from one or more of them, for example, polyvinyl chloride (abbreviation“ PV ”).
C ") and polyvinylidene chloride (abbreviated as" PVDC "), and a method for producing an aromatic dicarboxylic acid from a resin composition.

[0002]

2. Description of the Related Art A crude aromatic dicarboxylic acid produced by hydrolysis of a thermoplastic polyester, which is a crude aromatic dicarboxylic acid which still contains foreign substances, is used as a method for removing foreign substances. There is known a method for filtering foreign matter in a state of changing to (USP 4,542,239 and BA Barna, DR Ja.
hnsrud and RL Lamparter, Michigan Technological
University, Chemical Engineering, Dec. 1, 1980 ).

[0003]

The object of the present invention is primarily thermoplastic polyesters and chlorine-containing polyalkenes, in particular:
It is an object of the present invention to provide a method for producing an aromatic dicarboxylic acid containing no foreign matter from a resin composition composed of one or more of polyvinyl chloride and polyvinylidene chloride. The conventional method of removing the foreign matter by filtering the aqueous solution of the aromatic dicarboxylic acid diammonium salt is not suitable for industrial practice because it has the following drawbacks. -Low productivity due to low solubility of aromatic dicarboxylic acid diammonium salt-Neutralization of aromatic dicarboxylic acid diammonium salt requires an equivalent amount of acid.

[0004]

SUMMARY OF THE INVENTION We have found that chlorine-containing polyalkenes under the hydrolysis conditions of thermoplastic polyesters,
Above all, it has been found that polyvinyl chloride and / or polyvinylidene chloride decomposes and does not dissolve in an aprotic polar solvent. As a result of further study based on this finding, the present invention has been completed by solving the above problems. That is, a resin composition comprising a thermoplastic polyester as a main component and a chlorine-containing polyalkene as a subcomponent, especially polyvinyl chloride and / or polyvinylidene chloride is hydrolyzed to convert the polyester into an aromatic dicarboxylic acid, and then a crude dicarboxylic acid is prepared. After dissolving the aromatic dicarboxylic acid in an aprotic polar solvent,
By separating, for example, by filtering the impurities of the chlorine-containing polyalkene source that have been decomposed into insoluble matter, it is possible to remove the foreign matter with high productivity without accompanying salt by-products.

Therefore, according to the method of the present invention, a foreign matter-free aromatic dicarboxylic acid is obtained from a resin composition comprising a thermoplastic polyester as a main component and a chlorine-containing polyalkene as a subcomponent, particularly polyvinyl chloride and / or polyvinylidene chloride. It is an industrially advantageous method mainly in terms of cost for production.

That is, the present invention is constituted by the respective requirements defined in the following "basic constitution" and "improved constitution 1" to "improved constitution 6": [Basic constitution] heat which is a main component The thermoplastic polyester is hydrolyzed to convert the thermoplastic polyester into an aromatic dicarboxylic acid by hydrolyzing a resin composition comprising a chlorine-containing polyalkene as an auxiliary component, and the produced crude aromatic dicarboxylic acid is then dissolved in an aprotic polar solvent. And a method for producing an aromatic dicarboxylic acid, characterized in that the insoluble matter is separated.

[Improved Structure 1] The method for producing an aromatic dicarboxylic acid according to [Basic Structure], wherein the chlorine-containing polyalkene is at least one selected from polyvinyl chloride and polyvinylidene chloride.

[Improved constitution 2] The aromatic dicarboxylic acid described in "basic constitution" and "improved constitution 1", characterized in that the content of chlorine-containing polyalkene in the resin composition is 5% by weight or less. Production method.

[Improved Structure 3] The aprotic polar solvent is 1-
Aromatic group according to "basic constitution" and "improved constitution 1" and "improved constitution 2", which is one or more selected from methyl-2-pyrrolidone, N, N-dimethylformamide and dimethylsulfoxide. Method for producing dicarboxylic acid.

[Improved Structure 4] The "basic structure" and the "improved structure 1" in which the amount of the aprotic polar solvent used is 1 to 50 times the weight of the aromatic dicarboxylic acid to be dissolved.
-The manufacturing method of the aromatic dicarboxylic acid as described in "improved structure 3".

[Improved Construction 5] Hydrolysis is carried out at 200 ° C. to 30 ° C.
The method for producing an aromatic dicarboxylic acid according to "basic constitution" and "improved constitution 1" to "improved constitution 4", which is carried out at 0 ° C.

[Improved constitution 6] "Basic constitution" and "improved constitution 1" to "improved constitution" characterized in that the crude aromatic dicarboxylic acid is dissolved in an aprotic polar solvent at a temperature of 150 ° C or lower. 5. The method for producing an aromatic dicarboxylic acid according to 5 ”.

<Preferred embodiment of the invention><< Thermoplastic polyester >> The thermoplastic polyester in the present invention is selected from alkylene glycols such as ethylene glycol, ethylene oxide (also known as "ethylene oxide"), propylene glycol and propylene oxide. It is an aromatic polyester containing one or more species and one or more species selected from aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, alkyl-substituted products thereof, naphthalene dicarboxylic acid and diphenyl dicarboxylic acid.

<< Resin Composition >> The resin composition of the present invention comprises a thermoplastic polyester as a main component and a chlorine-containing polyalkene of 5% by weight (composition basis) or less as a subcomponent, for example, polyvinyl chloride and / or polychlorine. It is composed of vinylidene, and may contain one or more kinds of polyethylene, polypropylene, polystyrene, aluminum, glass, paper and the like in addition to the chlorine-containing polyalkene.

<< Aprotic polar solvent >> Examples of the aprotic polar solvent that can be used in the method of the present invention include 1-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide and tetra Methyl urea, 1,3-dimethyl
-2-One or more kinds of aprotic polar solvents selected from imidazolidinone, sulfolane and dimethyl sulfoxide. Among these, preferable are 1-methyl-2-pyrrolidone, N, N-dimethylformamide and dimethyl sulfoxide.

The amount of these aprotic polar solvents used is such that a saturated solution of an aromatic dicarboxylic acid is added at a temperature at which a foreign substance such as a chlorine-containing polyalkene decomposition product, particularly polyvinyl chloride decomposition product and / or polyvinylidene chloride decomposition product is not melted. The amount required to form is 1 to 50 times, preferably 3 to 10 times the weight of the aromatic dicarboxylic acid to be dissolved.
It is necessary to set double. These aprotic polar solvents may be used as a mixed solvent with water. In that case, the mixing ratio is based on weight, the former / the latter = 5/1 to 100/1,
It is preferably selected from 10/1 to 50/1.

<< Hydrolysis reaction >> The hydrolysis reaction of the thermoplastic polyester is usually carried out at a reaction temperature of 200 ° C. to 300 ° C. in the presence of water in an amount of at least twice the weight of the polyester.
C., preferably 220 to 260.degree. C., for 0.1 to 5 hours, preferably 0.5 to 2 hours with stirring. The reaction can be carried out under pressure if necessary.

<< Dissolution Separation >> The resulting crude aromatic dicarboxylic acid is dissolved in an aprotic polar solvent at a temperature of 150 ° C. or lower, preferably 100 to 120 ° C., and then insoluble matter is separated, for example, filtered off. This makes it possible to remove decomposition products such as polyvinyl chloride and other foreign matter in the crude aromatic dicarboxylic acid. At this time, the coloring matter and the like which are dissolved and accompanied by the aprotic polar solvent are purified by recrystallization and / or
Alternatively, it can be almost removed in a solution state by a conventional purification method such as purification with activated carbon.

<< Precipitation >> A solution of an aromatic dicarboxylic acid in an aprotic polar solvent is cooled or a poor solvent is added,
The aromatic dicarboxylic acid can be precipitated by further cooling if necessary. Examples of the poor solvent include water, lower alcohols having 3 or less carbon atoms, and acetonitrile, and one or more of them is usually 0.1 times or more, preferably 0 or more times the weight of the aprotic polar solvent. The purpose can be achieved by using more than 5 times.

[0020]

The present invention will be described below with reference to examples.
The present invention is not limited to these examples. A reference example is also presented.

[0021]

[Example 1] <First stage> 600 g of recycled PET flakes (manufactured by With PET Bottle Recycle Co.) containing a small amount of polyvinyl chloride, etc.
And 1800 g of water were stirred in an autoclave at 240 ° C. for 1 hour to hydrolyze PET. After cooling the reaction mixture to room temperature, the precipitate was filtered, washed with water and dried to obtain 511.4 g of crude terephthalic acid. It was also found that its terephthalic acid content was 91.3% according to high performance liquid chromatography analysis, and that it contained 8.5% of monohydroxyethyl ester.

Based on the concentration of diethylene glycol in the regenerated PET flakes of 1.4% (2.6 mol%), the terephthalic acid yield was 90.6%. The content of ethylene glycol in the filtrate and the washing liquid was quantified by gas chromatographic analysis, and the ethylene glycol yield was 8
It was found to be 8.1%.

<Second stage> 100 g of crude terephthalic acid obtained
600 g of 1-methyl-2-pyrrolidone was added to (purity 91.3%), and the mixture was heated with stirring at 100 ° C. for 30 minutes to give an insoluble matter (0.0
25 g) was filtered off and then cooled to room temperature. The precipitated crystals were filtered, washed with water and dried, and terephthalic acid (purity 97.5%) 61.
8 g (66.0% recovery) was obtained.

[0024]

[Example 2] To 100 g of the crude terephthalic acid obtained in "Example 1 <Previous stage>", 600 g of 1-methyl-2-pyrrolidone was added, and the mixture was heated and stirred at 100 ° C for 30 minutes, and the insoluble matter was filtered off, followed by filtration. 600 g of water as a poor solvent was added to the mixture and cooled to room temperature. The precipitate is filtered, washed with water and dried to remove terephthalic acid (purity 93.
(7%) 93.4 g (recovery 95.6%) was obtained.

[0025]

Example 3 The same procedure as in Example 2 was carried out except that methanol was used instead of water as the poor solvent in Example 2, and terephthalic acid (purity: 95.4%, containing no polyvinyl chloride decomposition products) was obtained. ) 75.3 g (recovery rate 78.7%)
was gotten.

[0026]

Example 4 Crude terephthalic acid (containing 20% by weight of water) obtained by washing the hydrolyzate in Example 1 <First stage> with water 1
Add 620 g of 1-methyl-2-pyrrolidone to 25 g of 100
After heating and stirring at 30 ° C. for 30 minutes, the insoluble matter was filtered off. The filtrate was cooled to room temperature, and the precipitated crystals were filtered, washed with water, and dried to give 53.7 g of terephthalic acid (purity 96.0%) containing no polyvinyl chloride decomposition products (recovery rate 56.5%).
was gotten.

[0027]

Example 5 To 100 g of the crude terephthalic acid obtained in Example 1 <Previous stage> was added 350 g of dimethyl sulfoxide to give 10
The mixture was heated and stirred at 0 ° C. for 30 minutes, the insoluble matter (0.025 g) was filtered off, and then cooled to room temperature. The precipitated crystals are filtered,
After washing with water and drying, 27.4 g (recovery rate 29.5%) of terephthalic acid (purity 98.2%) containing no polyvinyl chloride decomposition product was obtained.

[0028]

Example 6 To 100 g of the crude terephthalic acid obtained in Example 1 <Previous stage> was added 350 g of dimethyl sulfoxide to obtain 10 parts.
The mixture was heated and stirred at 0 ° C. for 30 minutes, the insoluble matter was filtered off, 350 g of water as a poor solvent was added to the filtrate, and the mixture was cooled to room temperature.
The precipitate is filtered, washed with water and dried, and terephthalic acid (purity 92.6%) does not contain polyvinyl chloride decomposition products.
94.6 g (recovery 96.0%) was obtained.

[0029]

Example 7 The same procedure as in Example 6 was carried out except that methanol was used instead of water, which was the poor solvent in Example 6, and terephthalic acid (purity: 95. 7%) 82.9 g (recovery rate 86.9
%)was gotten.

[0030]

Example 8 To 125 g of crude terephthalic acid (containing 20% by weight of water) obtained by washing with water after hydrolysis in Example 1 <First stage>, 450 g of dimethyl sulfoxide was added and heated and stirred at 100 ° C. for 30 minutes. After that, the insoluble matter was filtered off. Water (425 g) was added to the filtrate as a poor solvent, the mixture was cooled to room temperature, and the precipitated crystals were filtered, washed with water and dried to give 95.1 g of terephthalic acid (purity 92.7%) containing no polyvinyl chloride decomposition products (recovery). A rate of 96.6%) was obtained.

[0031]

[Example 9] The same procedure as in Example 8 was carried out except that 10 g of activated carbon was added, to obtain 94.3 g of terephthalic acid (purity 92.2%) (recovery rate 95.2%). It was

[0032]

[Example 10] A resin composition consisting of 114 g of PET for bottles and 6 g of washed and dried commercial polyvinyl chloride bottle and 342 g of water were placed in a corrosion resistant steel (trade name: Hastelloy) clad autoclave and stirred at 240 ° C for 2 hours. did. After cooling the reaction mixture to room temperature, the precipitate was filtered, washed with water and dried to obtain 102.6 g of crude terephthalic acid containing a decomposed product of polyvinyl chloride. Crude terephthalic acid 100
Add 350 g of dimethyl sulfoxide to g and add 1 at 100 ° C.
After heating and stirring for an hour, the insoluble matter (5.4 g) was filtered off, 350 g of water as a poor solvent was added to the filtrate, and the mixture was cooled to room temperature. The precipitate is filtered, washed with water and dried to remove terephthalic acid (purity 99.4
%) 94.5 g was obtained. The terephthalic acid recovery rate based on PET for bottles was 98.3%.

[0033]

Example 11 In 125 g of crude terephthalic acid (containing 20% by weight of water) obtained by washing with water after hydrolysis in Example 1 <first stage>, 1000 g of dimethylformamide was added, and the mixture was heated and stirred at 100 ° C. for 30 minutes. After that, the insoluble matter was filtered off. When 500 g of water as a poor solvent was added to the filtrate and cooled to room temperature, the precipitated crystals were filtered, washed with water and dried,
94.5 g (recovery rate 97.5%) of terephthalic acid (purity 94.2%) containing no polyvinyl chloride decomposition products was obtained.

[0034]

Reference Example 1 50 g of a commercially available polyvinyl chloride bottle washed and dried and 50 g of water and 2900 g of water were placed in a corrosion resistant steel (trade name: Hastelloy) clad autoclave and stirred under heating at 240 ° C. for 2 hours. After cooling the autoclave to room temperature, the insoluble matter was filtered, washed with water and dried to obtain 24.2 g of polyvinyl chloride decomposition product (recovery rate 48.4% based on the charged amount).

It was found that the decomposed product of polyvinyl chloride did not dissolve in 1-methyl-2-pyrrolidone or dimethyl sulfoxide at 100 ° C.

[0036]

According to the method of the present invention, refined terephthalate can be produced from polyester waste by an economically advantageous method in addition to exhibiting high productivity without salt by-product. .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masatoshi Kawauchi 6-1-2 Waki, Waki-cho, Kuga-gun, Yamaguchi Mitsui Petrochemical Industry Co., Ltd.

Claims (7)

[Claims] 1. A crude composition produced by hydrolyzing a resin composition comprising a thermoplastic polyester as a main component and a chlorine-containing polyalkene as a subcomponent to convert the thermoplastic polyester into an aromatic dicarboxylic acid and an alkylene glycol. A method for producing an aromatic dicarboxylic acid, which comprises dissolving the aromatic dicarboxylic acid in an aprotic polar solvent and separating the insoluble matter. 2. The method for producing an aromatic dicarboxylic acid according to claim 1, wherein the chlorine-containing polyalkene is at least one selected from polyvinyl chloride and polyvinylidene chloride. 3. The content of the chlorine-containing polyalkene in the resin composition is 5% by weight or less.
Or the method for producing an aromatic dicarboxylic acid according to item 2. 4. The aprotic polar solvent is one or more selected from 1-methyl-2-pyrrolidone, N, N-dimethylformamide, and dimethylsulfoxide. A method for producing the aromatic dicarboxylic acid described. 5. The production of an aromatic dicarboxylic acid according to claim 1, wherein the amount of the aprotic polar solvent used is 1 to 50 times the weight of the aromatic dicarboxylic acid to be dissolved. Method. 6. The method for producing an aromatic dicarboxylic acid according to claim 1, wherein the hydrolysis is performed at 200 ° C. to 300 ° C. 7. The method for producing an aromatic dicarboxylic acid according to claim 1, wherein the crude aromatic dicarboxylic acid is dissolved in an aprotic polar solvent at a temperature of 150 ° C. or lower. .