JPH08302061A - Recovery of aromatic dicarboxylic acid from waste aromatic polyester - Google Patents

Abstract

PURPOSE: To recover an aromatic dicarboxylic acid free from foreign material from waste polyester in high productivity. CONSTITUTION: A resin composition consisting of (a) PET as the main component, (b) PVC as a subsidiary component and (c) PE, etc., as admixed components is hydrolyzed at >=200 deg.C to regenerate terephthalic acid(PTA) from the PET. The regenerated crude PTA is dissolved in hot water at >=200 deg.C, PE, etc., are removed from the solution by extracting with an aromatic hydrocarbon and/or an aliphatic hydrocarbon and water-insoluble and infusible decomposed PVC, etc., are separated to recover TPA free from foreign material.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a thermoplastic polyester as the main component (a) such as polyethylene terephthalate (abbreviation "PET"), polybutylene terephthalate (abbreviation "PBT") or polyethylene naphthalene dicarboxylate (abbreviation "PEN"). ) A chlorine-containing polyalkene such as polyvinyl chloride (abbreviation “PVC”), chlorinated polyethylene and chlorine-containing alkylidene polymer as a sub-component (b) such as polyvinylidene chloride (abbreviation “PVDC”) A resin composition [1: (a) + (b)] composed of at least the following, or a polyalkene as a mixed component (c) optionally further mixed, such as polyethylene (“PE”) and polypropylene (“PP”) Foreign matter from the resin composition [2: (a) + (b) + (c)] which also contains one or more components selected from It relates to a process for the recovery of free aromatic dicarboxylic acids.

[0002]

BACKGROUND OF THE INVENTION Crude aromatic dicarboxylic acid is an aromatic dicarboxylic acid produced by hydrolysis of a thermoplastic polyester and is still an aromatic dicarboxylic acid containing a foreign substance. As a method for removing foreign matter from this crude aromatic dicarboxylic acid, a method of filtering the foreign matter in a state where the crude aromatic dicarboxylic acid is changed to a diammonium salt is already known (USP 4,542,239 and BA Braun. ,
DR Jahnsrud and RL Lampparter, Michigan Techn
ological University, Chemical Engineering , Dec. 1,
1980). This method is not suitable for industrial use 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.

[0003]

The object of the present invention is to provide a main component
A resin composition comprising at least a thermoplastic polyester as (a) and a chlorine-containing polyalkene as a subcomponent (b) such as polyvinyl chloride and chlorinated polyethylene, a chlorine-containing alkylidene polymer such as polyvinylidene chloride [1: (a ) + (b)] or a resin composition [2: (a) + (b) + in which one or more of polyalkene such as polyethylene and polypropylene coexists as the mixed component (c) in the resin composition]
(c)], there is provided a method for recovering an aromatic dicarboxylic acid containing no foreign matter.

That is, the method of the present invention is a problem of the conventional method and is difficult (low productivity) when an aromatic dicarboxylic acid diammonium salt is made into an aqueous solution, and the diammonium salt is filtered to remove foreign matters. It is an object to fundamentally solve the problem that an equivalent amount of acid is required to neutralize the diammonium salt after the heating.

[0005]

SUMMARY OF THE INVENTION We have found that chlorine-containing polyalkenes under the hydrolysis conditions of thermoplastic polyesters,
It has been found that, among them, polyvinyl chloride and / or chlorine-containing alkylidene polymers, and especially polyvinylidene chloride, are insoluble in water and do not melt even at 300 ° C. or higher depending on the hydrolysis treatment conditions. As a result of further studies based on this finding, the present inventors have succeeded in clarifying the conditions for producing an infusible substance, applied the conditions to solve the above problems, and completed the present invention.

That is, thermoplastic polyester as the main component (a) and chlorine-containing polyalkene as the sub-component (b), for example,
Polyvinyl chloride or chlorinated polyethylene and / or chlorine-containing alkylidene polymer, for example, a resin composition [1: (a) + (b)] composed of at least polyvinylidene chloride is hydrolyzed to convert the polyester into an aromatic dicarboxylic acid. The crude aromatic dicarboxylic acid obtained by the conversion is dissolved in water and then insoluble in water in the chlorine-containing polyalkene decomposition product and / or insoluble in water in the chlorine-containing alkylidene polymer decomposition product. It is possible to recover the target aromatic dicarboxylic acid with high productivity by separating the infusible portion, for example, by filtering out, without removing an equivalent amount of acid, removing foreign substances without causing salt by-product. it can.

In another embodiment, a resin composition [2: (a) + (b) + (c) in which a polyalkene etc., for example, polyethylene and / or polypropylene etc. coexist as a mixed component (c) in the above resin composition, as the case may be. )] Is hydrolyzed to convert the polyester to an aromatic dicarboxylic acid, and the resulting crude aromatic dicarboxylic acid is dissolved in water and then extracted with an aromatic hydrocarbon and / or an aliphatic hydrocarbon to form a mixed polyalkene. By removing, then separating the water-insoluble and infusible parts in the chlorine-containing polyalkene hydrolyzate and / or the water-insoluble and infusible parts in the chlorine-containing alkylidene polymer hydrolyzate, for example by filtering off It is possible to recover the target aromatic dicarboxylic acid with high productivity by removing the foreign matter without the salt by-product, without requiring an equivalent amount of acid.

Accordingly, the process of the present invention comprises a thermoplastic polyester as the main component (a) and a chlorine-containing polyalkene, especially polyvinyl chloride and / or a chlorine-containing alkylidene polymer, especially polyvinylidene chloride as the subcomponent (b). Resin composition [1: (a) + (b)], optionally a resin composition [2: (a) + in which polyethylene and / or polypropylene coexist, such as a polyalkene (c) and the like.
(b) + (c)] is an industrially remarkably advantageous method for recovering an aromatic dicarboxylic acid containing no foreign matter, mainly in terms of cost and by-products.

<Preferred Embodiment of the Invention> The present invention is constituted by the respective requirements defined in the following "basic constitution" and "improved constitution 1" to "improved constitution 6": [1. absence of polyalkene Basic composition of the system] A resin composition [1: (a) + (b) comprising at least a thermoplastic polyester (a) as a main component and a chlorine-containing polyalkene or a chlorine-containing alkylidene polymer (b) as a subcomponent )] 200
Hydrolyze at ~ 300 ° C to regenerate the aromatic dicarboxylic acid from the thermoplastic polyester and decompose the chlorine-containing polyalkene and / or chlorine-containing alkylidene polymer to form a water-insoluble and infusible decomposition product, A method for recovering an aromatic dicarboxylic acid, which comprises dissolving the regenerated crude aromatic dicarboxylic acid in an aqueous solvent, and separating and removing a portion insoluble in water and infusible.

[2. Improved configuration 1 of polyalkene-free system]
The fragrance according to Item 1, wherein the chlorine-containing polyalkene in the resin composition [1: (a) + (b)] is polyvinyl chloride and / or chlorinated polyethylene, and the chlorine-containing alkylidene polymer is polyvinylidene chloride. For recovering aromatic dicarboxylic acids.

[3. Improved configuration 2 of polyalkene absence system]
Item 3. The method for recovering aromatic dicarboxylic acid according to Item 1 or 2, wherein the content of the chlorine-containing polyalkene in the resin composition [1: (a) + (b)] is 10% by weight or less.

[4. Basic configuration of polyalkene mixed system]
A resin composition comprising a thermoplastic polyester (a) as a main component, a chlorine-containing polyalkene or a chlorine-containing alkylidene polymer (b) as a subcomponent, and a polyalkene (c) as a mixed component [2: (a) + ( b) + (c)] is hydrolyzed at 200 to 300 ° C. to regenerate an aromatic dicarboxylic acid from the thermoplastic polyester, and at the same time, a chlorine-containing polyalkene and / or
Alternatively, the chlorine-containing alkylidene polymer is decomposed to form a water-insoluble and infusible decomposition product, and then the regenerated crude aromatic dicarboxylic acid is dissolved in an aqueous solvent, and an aromatic hydrocarbon and / or an aliphatic hydrocarbon To remove polyalkene, etc., and further remove the water-insoluble and / or insoluble portion in the decomposition product of chlorine-containing polyalkene and / or the water-insoluble and insoluble portion in the decomposition product of chlorine-containing alkylidene polymer. A method for recovering an aromatic dicarboxylic acid, which comprises separating and removing.

[5. Improved configuration 2 of polyalkene mixed system]
Item 4. The chlorine-containing polyalkene in the resin composition [2: (a) + (b) + (c)] is polyvinyl chloride and / or chlorinated polyethylene, and the chlorine-containing alkylidene polymer is polyvinylidene chloride. The method for recovering an aromatic dicarboxylic acid according to 1.

[6. Improved configuration 3 of polyalkene mixed system]
6. The aromatic dicarboxylic acid according to item 4 or 5 above, wherein the content of the chlorine-containing polyalkene in the resin composition [2: (a) + (b) + (c)] is 10% by weight or less. Recovery method.

[7. Improved configuration 4 of polyalkene mixed system]
The polyalkene in the resin composition [2: (a) + (b) + (c)] is one or more selected from polyethylene and polypropylene, and the aroma according to any one of items 4 to 6 above. For recovering aromatic dicarboxylic acids.

[8. Improved configuration 5 of polyalkene mixed system]
The content of the polyalkene in the resin composition [2: (a) + (b) + (c)] is 20% by weight or less, and
8. The method for recovering an aromatic dicarboxylic acid according to any of 7.

[9. Improved construction 6 of polyalkene mixed system]
Item 9. The aromatic hydrocarbon is one or more selected from toluene, xylene, cumene, and chlorobenzene, and the aliphatic hydrocarbon is one or more selected from hexane and decane. Method for recovering aromatic dicarboxylic acid.

[10. Improved configuration 7 of mixed polyalkene system] The amount of aromatic hydrocarbon and / or aliphatic hydrocarbon used is 5 to the weight of polyalkene to be extracted and removed.
Item 10. The method for recovering aromatic dicarboxylic acid according to any one of Items 4 to 9, which is 100 times.

[11. Improved configuration 8 of polyalkene-mixed system] [0019] In any one of the above items 4 to 10, characterized in that the extraction separation with an aromatic hydrocarbon and / or an aliphatic hydrocarbon is carried out at 200 to 300 ° C. A method for recovering aromatic dicarboxylic acid.

<Preferred Embodiments of the Invention><< Thermoplastic Polyester (a) >> The thermoplastic polyester in the present invention is formed by polycondensation of an aromatic dicarboxylic acid and an alkylene glycol or an alkylene oxide (also known as "alkylene oxide"). Is an aromatic polyester. Here, the aromatic dicarboxylic acid is, for example, one or more kinds of dicarboxylic acids selected from terephthalic acid, isophthalic acid, alkyl-substituted products thereof, naphthalenedicarboxylic acid, diphenyldicarboxylic acid and the like.

The alkylene glycol and alkylene oxide are, for example, one or more selected from ethylene glycol and ethylene oxide (alias "ethylene oxide") and propylene glycol and propylene oxide (alias "propylene oxide").

<< Resin Composition >> The resin composition to be treated in the present invention is a resin composition [1: (a) + (b)] or a resin composition [2: (a) + (b) +. (c)]. Resin composition [1:
(a) + (b)] is a thermoplastic polyester as the main component (a) and 10% by weight (composition basis) or less of a chlorine-containing polyalkene as a subcomponent (b), for example, polyvinyl chloride and / or a chlorine-containing alkylidene polymer. For example, it is mainly composed of polyvinylidene chloride.

The resin composition [2: (a) + (b) + (c)] further comprises 2
0% by weight or less of polyalkene, such as polyethylene and / or polypropylene, coexists as a mixed component. Of course, in addition to these, one or more of polystyrene, aluminum, glass, paper and the like may be contained.

<< Aromatic Hydrocarbon >> The aromatic hydrocarbon used for extracting and removing the mixed polyalkene in the method of the present invention is a liquid at ordinary temperature, for example, benzene,
It is one or more aromatic hydrocarbons selected from toluene, xylene, cumene, mesitylene, pseudocumene, diisopropylbenzene, naphthalene, alkyl-substituted naphthalene, chlorobenzene and dichlorobenzene. Preferred among these are xylene, toluene and cumene.

<< Aliphatic Hydrocarbon >> The aliphatic hydrocarbon used for extracting and removing the mixed polyalkene in the method of the present invention includes, for example, pentane, hexane, octane, nonane, decane, dodecane, tridecane, tetradecane and It is one or more aliphatic hydrocarbons selected from pentadecane. Among these, hexane and decane are preferable.

The hydrolysis reaction of the thermoplastic polyester in << hydrolysis reaction >><< previous stage >> is usually carried out at a reaction temperature of 200 to 300 ° C., preferably in the presence of water in an amount not less than twice the weight of the polyester. Under pressure sufficient to maintain the water in the liquid phase at 220 to 260 ° C, usually 20 to 100 kg
It can be carried out by heating to f / cm ² · G for 0.1 to 5 hours, preferably 0.5 to ² hours. The reaction may be carried out in the presence of a base approximately equal to the amount necessary for neutralizing hydrogen chloride derived from the chlorine-containing polyalkene and / or the chlorine-containing alkylidene polymer, or may be carried out with stirring if necessary. it can.

<< Separation of Foreign Substances >> The crude aromatic dicarboxylic acid recovered in the <first stage> is 200 to 300 in the second stage.
5 to 60 times the amount of the crude aromatic dicarboxylic acid at a temperature of ℃, preferably 230 to 270 ℃, preferably 7 to
After being dissolved in 15 times the amount of hot water under pressure, the mixed polyalkene is extracted and removed with an aromatic hydrocarbon and / or an aliphatic hydrocarbon, and then insoluble in water in the chlorine-containing polyalkene decomposition product by filtration or the like. The melted portion and / or the water-insoluble and infusible portion and other foreign matter in the chlorine-containing alkylidene polymer decomposition product can be removed.

The pressure applied to the treatment system when dissolved in this hot water is sufficient if the coexisting water is maintained in the liquid phase.

The amount of the aromatic hydrocarbon and / or the aliphatic hydrocarbon used for removing the foreign matter is the amount necessary to dissolve the polyalkene (c) which is a mixed component mixed in the auxiliary component. The weight of the polyalkene to be extracted and removed should be set to 5 to 100 times, preferably 10 to 50 times. A mixed solvent of an aromatic hydrocarbon and an aliphatic hydrocarbon can also be used as the extraction solvent.

During the above-mentioned treatment, the coloring matter dissolved in water and accompanying the filtrate is removed by a usual purification method such as purification by recrystallization and / or activated carbon treatment in a solution state or purification by hydrogenation treatment. can do.

[0031]

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

[0032]

[Example 1] <First stage> Recycled PET flakes containing a small amount of polyvinyl chloride (manufactured by With PET Bottle Recycle Co.) 150
g, washed and dried commercial polyvinyl chloride bottle 0.9
g, 16.8 g of high-density polyethylene and 450 g of water were stirred in an autoclave at 240 ° C. for 2 hours to hydrolyze PET. After cooling the reaction mixture to room temperature, the precipitate was filtered, washed with water and dried to obtain 140.1 g of crude terephthalic acid. The results are shown in <Previous Stage> in Table 1.

<Second stage> 1200 g of water and 336 g of xylene were added to crude terephthalic acid, and the mixture was placed in an autoclave at 255 ° C.
The mixture was heated and stirred for 1 h, and the xylene layer was separated. Then 25
The insoluble matter was filtered off under pressure at 5 ° C., the obtained filtrate was cooled to room temperature, and the precipitated crystals were collected by filtration, washed with water and dried to obtain terephthalic acid containing neither polyvinyl chloride nor high-density polyethylene. 121.8 g were obtained. Its terephthalic acid content (purity) was found to be 99.2% by high performance liquid chromatography analysis.

The recovery rate of terephthalic acid was determined to be 1.4% (2.6 mol%) of diethylene glycol in the recycled PET flakes.
It was 93.7% when calculated based on. The results are shown in <latter stage> of Table 1.

[0035]

[Embodiments 2 and 3] <First stage> was carried out in the same manner as in <First stage> of Example 1 except that the conditions of <Second stage> in the same example were changed to the conditions shown in Table 1. The results are shown in Table 1 <
The latter stage>.

[0036]

Example 4 The <previous stage> was carried out in the same manner as in Example 1 under the conditions shown in Table 1, and the mixed solvent [xylene / hexane = shown in Table 1 was used instead of xylene in the <second stage> of the same example.
90/10 (weight basis; the sum of the two is 100)] was used under the conditions shown in Table 1 and in the same manner as in Example 1 <latter stage>. The extraction results are shown in <latter stage> of Table 1.

[0037]

[Example 5] <First stage> Recycled PET flakes containing a small amount of polyvinyl chloride (manufactured by With PET Bottle Recycle Co.) 150
g, Washed and dried commercial polyvinyl chloride bottle 21.4
g, high density polyethylene 42.8g, sodium hydroxide 1
3.7g and 450g of water in an autoclave at 240 ° C for 2h
The PET was hydrolyzed with stirring. After cooling the reaction mixture to room temperature, the precipitate was filtered, washed with water and dried to obtain 173.6 g of crude terephthalic acid. The results are shown in Table 1
Shown in

<Post-stage> 1200 g of water and 856 g of xylene were added to the crude terephthalic acid, and the mixture was stirred at 255 ° C. for 1 hour to separate the xylene layer. Then, the insoluble matter was filtered off at 255 ° C., the filtrate was cooled to room temperature, and the precipitated crystals were filtered, washed with water and dried to give terephthalic acid 120. 1 g was obtained. The terephthalic acid recovery rate was 92.3%. The results are shown in <latter stage> of Table 1.

[0039]

[Example 6] <First stage> Recycled PET flakes (manufactured by With PET Bottle Recycle Co.) containing a small amount of polyvinyl chloride, etc. 150
g, Washed and dried commercial polyvinyl chloride bottle 10.0
g, crystalline polypropylene 10.0 g, sodium hydroxide 6.5 g and water 300 g in an autoclave at 250 ° C. for 2 hours.
The PET was hydrolyzed with stirring. After cooling the reaction mixture to room temperature, the precipitate was filtered, washed with water and dried to obtain 140.2 g of crude terephthalic acid. The results are shown in Table 1
Shown in

<Post-stage> 900 g of water and 100 g of toluene were added to the crude terephthalic acid, and the mixture was stirred at 270 ° C. for 2 hours, and the toluene layer was separated. Then, the insoluble matter was filtered off at 270 ° C., the filtrate was cooled to room temperature, and the precipitated crystals were filtered, washed with water and dried to obtain 92.0% pure terephthalic acid containing polyvinyl chloride and crystalline polypropylene. 1 g was obtained. The recovery rate of terephthalic acid was 92.2%. The results are shown in <latter stage> of Table 1.

[0041]

[Example 7] <First stage> Recycled PET flakes containing a small amount of polyvinyl chloride and the like (made by Wiz PET Bottle Recycle Co.) 150
g, Washed and dried commercial polyvinyl chloride bottle 10.0
g, high density polyethylene 5.0 g, sodium hydroxide 6.5
g and 300 g of water were stirred in an autoclave at 250 ° C. for 2 hours to hydrolyze PET. After cooling the reaction mixture to room temperature, the precipitate was filtered, washed with water and dried to obtain 135.7 g of crude terephthalic acid. The results are shown in <Previous Stage> in Table 1.

<Post-stage> 900 g of water and 250 g of hexane were added to the crude terephthalic acid and the mixture was stirred at 260 ° C. for 2 hours to separate the hexane layer. Then, the insoluble matter was filtered off at 260 ° C., the filtrate was cooled to room temperature, and the precipitated crystals were filtered, washed with water and dried to give 91.2% pure terephthalic acid 121.2 free of polyvinyl chloride and high-density polyethylene. 0 g was obtained. The recovery rate of terephthalic acid was 93.1%. The results are shown in <latter stage> of Table 1.

[0043]

EFFECTS OF THE INVENTION According to the method of the present invention, in addition to the fact that the aromatic polyester waste does not easily affect the environment in that it is not accompanied by salt by-product, which is difficult to discard and reuse, it is possible to realize high productivity. Thus, it is economically advantageous to recover an aromatic dicarboxylic acid containing no foreign matter, particularly terephthalic acid.

[0044]

[Table 1]

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location // B29B 17/00 ZAB 9350-4F B29B 17/00 ZAB B29K 67:00 105: 26

Claims (11)

[Claims] 1. A thermoplastic polyester (a) as a main component
The thermoplastic polyester obtained by hydrolyzing a resin composition [1: (a) + (b)] at least at 200 to 300 ° C., which comprises at least a chlorine-containing polyalkene or a chlorine-containing alkylidene polymer (b) as an accessory component. Aromatic dicarboxylic acid is regenerated from the compound, and the chlorine-containing polyalkene and / or chlorine-containing alkylidene polymer is decomposed to form a water-insoluble and infusible decomposition product, and then the regenerated crude aromatic dicarboxylic acid is used as an aqueous solvent. A method for recovering an aromatic dicarboxylic acid, which comprises dissolving and at the same time separating and removing an insoluble portion and the like in water. 2. The resin composition [1: (a) + (b)] in which the chlorine-containing polyalkene is polyvinyl chloride and / or chlorinated polyethylene, and the chlorine-containing alkylidene polymer is polyvinylidene chloride. The method for recovering an aromatic dicarboxylic acid according to 1. 3. The aromatic dicarboxylic acid according to claim 1, wherein the content of the chlorine-containing polyalkene in the resin composition [1: (a) + (b)] is 10% by weight or less. Acid recovery method. 4. A thermoplastic polyester (a) as a main component
And chlorine-containing polyalkene or chlorine-containing alkylidene polymer (b) as a subcomponent and polyalkene as a mixed component
20% of a resin composition [2: (a) + (b) + (c)] consisting of (c), etc.
Aromatic dicarboxylic acid is regenerated from the thermoplastic polyester by hydrolysis at 0 to 300 ° C., and a chlorine-containing polyalkene and / or a chlorine-containing alkylidene polymer is decomposed to form a water-insoluble and infusible decomposition product, Then, the regenerated crude aromatic dicarboxylic acid is dissolved in an aqueous solvent, and the polyalkene or the like is removed by extraction with an aromatic hydrocarbon and / or an aliphatic hydrocarbon, and further the water in the decomposition product of the chlorine-containing polyalkene is added. A method for recovering an aromatic dicarboxylic acid, characterized in that an insoluble and infusible portion and / or a water-insoluble and infusible portion in a decomposition product of a chlorine-containing alkylidene polymer are separated and removed. 5. The chlorine-containing polyalkene in the resin composition [2: (a) + (b) + (c)] is polyvinyl chloride and / or chlorinated polyethylene, and the chlorine-containing alkylidene polymer is polyvinylidene chloride. The method for recovering aromatic dicarboxylic acid according to claim 4, wherein 6. The resin composition [2: (a) + (b) + (c)] in which the content of chlorine-containing polyalkene is 10% by weight or less, wherein A method for recovering aromatic dicarboxylic acid. 7. The polyalkene in the resin composition [2: (a) + (b) + (c)] is one or more selected from polyethylene and polypropylene, and any one of claims 4 to 6 is characterized. A method for recovering an aromatic dicarboxylic acid according to Crab. 8. The resin composition [2: (a) + (b) + (c)] in which the content of polyalkene is 20% by weight or less. A method for recovering the aromatic dicarboxylic acid described. 9. The aromatic hydrocarbon is toluene, xylene,
The method for recovering an aromatic dicarboxylic acid according to claim 4, wherein the aromatic hydrocarbon is at least one selected from cumene and chlorobenzene, and the aliphatic hydrocarbon is at least one selected from hexane and decane. 10. The aromatic compound according to claim 4, wherein the amount of the aromatic hydrocarbon and / or the aliphatic hydrocarbon used is 5 to 100 times the weight of the polyalkene to be extracted and removed. Method for recovering dicarboxylic acid. 11. The method for recovering an aromatic dicarboxylic acid according to claim 4, wherein the extraction and separation with an aromatic hydrocarbon and / or an aliphatic hydrocarbon is performed at 200 to 300 ° C.