JPH0649749B2 - Method for recovering aromatic polyester product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of recovering a polyester product from an organic solution of an aromatic polyester product produced by interfacial polymerization. More specifically, after the substitution solvent is added to and mixed with the organic solvent solution of the aromatic polyester product obtained by the interfacial polymerization, the mixed solution of the product is added to warm water under stirring to recover the aromatic polyester. The present invention relates to a new method for recovering an aromatic polyester having improved hue and transparency and a small flake thickness.

Generally, an aromatic polyester product produced from terephthalic acid and isophthalic acid or derivatives thereof and bisphenol-A or a derivative thereof has already been commercialized and produced as a resin having excellent thermal and mechanical performance. There is.

The aromatic polyester product can be readily prepared by interfacial polymerization, and various methods have been used to recover the product after interfacial polymerization.

For example, in U.S. Pat.Nos. 3,884,990 and 4,390,682 and Japanese Patent Publication No. 55-44098, an organic solvent solution of an aromatic polyester product is heated to a high temperature to evaporate the organic solvent, or an aromatic polyester product. The organic solvent solution of 1 is added to warm water to recover the product, or the product is added to a solvent (hereinafter referred to as “non-solvent”) that does not dissolve the polymer, such as acetone or ethanol. A method of depositing and recovering is proposed.

However, when the organic solution of the product is heated at a high temperature by these methods, physical properties such as discoloration are likely to occur, and when it is recovered by adding it to warm water, a considerable amount of the organic solution of the product used at the time of polymerization remains. In addition, the flakes of the recovered product expand and become bulky compared to the weight, which is inconvenient to use, and the product may be removed in a non-solvent such as acetone or ethanol. In the case of precipitation and recovery, there are many problems in that a large amount of non-solvent is required and a step of separating and recovering the solvent and the requisite solvent is also required.

Therefore, according to the present invention, the solvent used can be easily separated and recovered by improving the recovery method after the interfacial polymerization of the aromatic polyester product, and the recovered product can be produced by reducing the flake volume. It is an object of the present invention to provide a new method for recovering an aromatic polyester, which facilitates the handling of the product and improves the hue and transparency of the product.

That is, the present invention, in recovering the aromatic polyester product from the organic solution of the aromatic polyester product produced by interfacial polymerization, the organic solution of the product and the organic solvent of the product used during the interfacial polymerization After mixing the non-solvent of the displaceable product, the organic solvent used at the time of polymerization is recovered by evaporating and collecting it while charging or spraying it in warm water which is being heated and stirred in a separate container. And the aromatic polyester product is recovered by filtration.

The present invention will be described in more detail as follows.

In the present invention, an organic solution of an aromatic polyester product obtained by interfacial polymerization of an alkaline aqueous solution of bisphenols and an organic solution of an aromatic carbonyl compound is prepared, and the organic solvent of the product used at the time of polymerization is replaced with the organic solution. After mixing the non-solvent of the product, the non-solvent mixed solution of the mixed product may be charged or sprayed into another container while heating and stirring hot water, and the organic solvent of the product may be added. The organic solvent is evaporated or separated and recovered at the same time as the above-mentioned product is charged or jetted to evaporate the organic solvent, and then the product is precipitated in the form of flakes from warm water. Collect the product.

Specific examples of the bisphenols used in the production of the aromatic polyester product in the present invention include bis (4-hydroxy-2-methylphenyl) ether, 4,4'-dihydroxydiphenyl ether and bis (4-hydroxy-3).
-Chlorophenyl) ether, bis (4-hydroxyphenyl) sulfide, bisphenol-S, bis (4
-Hydroxyphenyl) ketone, bis (4-hydroxyphenyl) ethane, bis (4-hydroxy-3-ethylphenyl) methane, 1,1-bis (4-hydroxyphenyl) methane, bis (4-hydroxy-3) , 5-Dibromophenyl) methane, 1,1-bis (4-hydroxyphenyl) methane, bisphenol-A, 2,2-bis (4-hydroxy-3-phenylethyl) propane, 2,2-bis ( 4-hydroxy-3,5-dichlorophenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) isobutane, 3,3 ', 5,5 ″, Tetramethyl-4,4′-dihydroxybiphenyl, 2,2-bis (3 ″, 5 ″ -dibromo4 ″ -hydroxyphenyl) propane, and the like, which may be used alone or in combination. Use as a mixture of the above You can

Specific examples of the aromatic carbonyl compound include terephthalic acid dichloride, terephthalic acid dibromide, isophthalic acid dichloride, isophthalic acid dibromide and the like.

The organic solvent of the product used for the interfacial polymerization in the present invention is a hydrocarbon or a hydrocarbon substituted with a halogen, and specific examples thereof include methylene chloride, chloroform, trichloroethylene, 1,2-dichloroethane, tetrachloroethane and benzene. , Ethylbenzene and the like can be mentioned, but in consideration of recovery of these solvents, methylene chloride, chloroform and the like having a relatively low boiling point are preferable. The organic solvents for these products may be used alone or in admixture of two or more.

The non-solvent of the above product used in the present invention includes saturated or unsaturated aliphatic hydrocarbons having 6 to 12 carbon atoms such as hexane and heptane, ketones such as methyl ethyl ketone, and fragrances such as chlorobenzene. Examples thereof include group organic solvents. These solvents are not compatible with the aromatic polyester product but must be compatible with the organic solvent of the product, and the boiling point is 10 ° C or more than the organic solvent of the product used during the polymerization, More preferably, it should be higher than 20 ° C. These non-solvents may be used alone or in 2
A mixture of two or more species can be used.

The amount of such a non-solvent of the product added is appropriately such that when the non-solvent of the product is added to the organic solution of the aromatic polyester product, the product is not precipitated and a slurry is formed. If the amount of the non-solvent added to the product is not too large, the product will gel and the product cannot be recovered when sprayed into warm water to recover the product. If it is too small, a sufficient effect is expected. Difficult to do.

Further, the non-solvent of the product used at this time must be compatible with the organic solvent used during polymerization, and the boiling point is 10 ° C or higher than the boiling point of the organic solvent used during polymerization,
Desirably, the temperature should be 20 ° C. or higher, and the organic solvent of the product should not be distilled together when it is separated and recovered.

Further, according to the present invention, when the mixed solution of the product in which the non-solvent is mixed as described above is loaded into hot water or jetted, the hot water has to be heated and stirred, and at that time, the temperature for heating the hot water Must be distilled only at the temperature between the boiling point of the organic solvent used during the polymerization and the boiling point of the non-solvent added to the organic solution of the product, and not the non-solvent.

Next, a method for producing an organic solution of an aromatic polyester product by interfacial polymerization will be described in detail below.

First, an appropriate alkaline component such as sodium hydroxide or calcium hydroxide is dissolved in water to prepare an alkaline solution, and the bisphenol component is dissolved therein to prepare an aqueous bisphenol solution. At this time, the addition amount of the alkali component is 1 to 1.2 times, preferably 1 to 1.1 times, the molar ratio with respect to the bisphenol component, and the addition amount of the bisphenol component is the molar ratio with the aromatic carbonyl compound. 1: 0.
It should be in the range of 9 to 0.9: 1.

The concentration of the bisphenol component with respect to the alkaline aqueous solution is such that the weight of the bisphenol component is 1 of the alkaline aqueous solution.
Try to keep the range between ~ 30%.

On the other hand, in another container, an aromatic carbonyl compound such as terephthaloyl dihalide and isophthaloyl dihalide is used in an appropriate ratio as a solvent for the aromatic polyester product such as the above-mentioned hydrocarbon or hydrocarbon substituted with halogen. However, the molar ratio of the aromatic carbonyl compound to the bisphenol component is adjusted to be in the range of 1 to 0.9 to 0.9: 1. The solvent of the aromatic polyester product used at this time has a boiling point of 10 ° C. or more, preferably 20 ° C. or higher than the boiling point of the non-solvent of the product to be used when recovering the product.
Must be lower than ℃.

The concentration of the aromatic carbonyl compound in the product solvent is set so that the weight of the aromatic carbonyl compound is in the range of 1 to 20% of the weight of the product solvent. If the solvent used at this time is not the solvent for the product, the product cannot have a sufficient degree of polymerization for use as a resin.

In the present invention, if necessary, a phase transfer catalyst, a dispersant,
Antioxidants, viscosity stabilizers, etc. may be added and used. Specific examples of the phase transfer catalyst include trimethylbenzylammonium hydroxide, trimethylbenzylammonium chloride, triethylbenzylammonium hydroxide, triethylbenzylammonium chloride and the like. A quaternary ammonium salt is effective, and sodium lauryl sulfate is effective as a dispersant.

As the antioxidant, sodium hydrosulfite, sodium bisulfite and the like can be used, and as the viscosity stabilizer, phenol, o-phenylphenol, p-phenylphenol, β-naphthol, pt-t- Butylphenol, o-t-butylphenol, isopropyl alcohol, t-butyl alcohol, m-cresol, o-
Monovalent phenols or alcohols such as cresol can be used. When such a viscosity stabilizer is used, the molecular weight distribution of the product can be controlled and a stable end group can be formed to improve the stability of the product.

These additives can be used alone or as a mixture of two or more kinds, and each component can be used within the range of 0.01 to 5% by weight of the product, and can be used together with the alkaline aqueous solution. It can be used by adding it or by adding it to the reaction product at the initial stage of the reaction.

On the other hand, in the present invention, the polyester product is polymerized by charging an alkaline aqueous solution of bisphenol and an organic solution of an aromatic carbonyl compound into a reaction tank for 5 minutes to 5 hours, preferably 30 minutes.
The reaction is carried out with vigorous stirring for a period of from minutes to 2 hours.

At this time, the reaction pressure is normal pressure and the reaction temperature is room temperature, but the reaction proceeds at 0-40 ° C, more specifically at 5-25 ° C.
Desirably between ℃.

After the reaction is completed in this way, use a centrifuge or let it stand to separate the aqueous solution layer and the organic solution layer in which the aromatic polyester product is dissolved, and then gently separate the upper aqueous solution layer. The pH of the organic solution layer obtained by pouring out is about 7
Wash with water several times to a certain degree, or add a weak acid to wash.

When the washing is completed, the aqueous solution layer and the organic solution layer in which the product is melted are separated again to take out the organic solution layer. At this time, the degree of polymerization of the product was recovered in a solid state and dissolved using a mixed solvent of phenol / tetrachloroethane (polymerization ratio 6/4) so that the solution concentration of the polymer became 0.5 g / d. Then, using an Ostwald viscometer, the logarithmic viscosity η _inh should be in the range of 0.3 to 3.0 d / g when determined as follows.

In this formula, t ₁ and t ₂ are the time during which the solution and the solvent flow, c
Is the concentration of the polymer solution.

If the logarithmic viscosity of the polymer is less than this, during molding of the product, mechanical strength such as impact strength, tensile strength, flexural strength, etc. is poor and it is difficult to use for molded articles and other applications, If it is larger than this, the melt viscosity becomes large and the molding temperature becomes high, which makes the processing difficult.

The method of separating and recovering the product and the organic solvent of the product from the organic solution of the aromatic polyester product thus prepared is as follows.

That is, a non-solvent that is compatible with the organic solvent of the product used during polymerization by stirring the solution of the produced aromatic polyester product but is incompatible with the product itself is an organic solution of the product. Is added to the extent that it becomes a slurry and then stirred again to form a uniform slurry-like solution.

Then, on the other hand, while warm water is stirred while heating the warm water at a temperature between the boiling point of the organic solvent of the product used at the time of polymerization and the boiling point of the non-solvent added to the organic solution of the product, warm water is put in another container. , Spraying or charging a solution of the slurry-like product mixed with the above non-solvent to distill and recover the organic solvent of the product used at the time of polymerization, and at that time, the product may be precipitated in warm water. Then, the precipitated flaky product is collected by filtration, and the non-solvent used is separated from water by layer separation or is collected by distillation, and thus the polyester product is collected.

As described above, when the aromatic polyester product is recovered by the method of the present invention, the product recovery step is simple and easy, the product can be easily separated and recovered, and the hue of the recovered product In addition, the transparency can be improved, and the bulk (bulk) of the recovered product flakes can be reduced, and the workability at the time of drying and pelletizing can be greatly improved.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 60 ml of water and 1350 g of sodium hydroxide were placed in a homomixer type reactor which was stirred at a high speed to prepare an alkaline aqueous solution, and 420 g of bisphenol-A was added and uniformly dissolved under stirring, and then triethylbenzylammonium chloride was added. 15
g was added and stirred to form a uniform solution.

1525 g of terephthaloyl dichloride and 1525 of isophthaloyl dichloride were added to methylene chloride in the resulting solution.
An organic solution in which g was dissolved was added and vigorously stirred and reacted for 90 minutes.

After completion of the reaction, the reaction solution was allowed to stand and separated into an aqueous solution layer and an organic solution layer, and then the aqueous solution layer was poured out to leave only the organic solution layer. Next, 5% acetic acid solution 50 was added to this organic solution layer, and then vigorously stirred to wash sodium chloride and alkali components in the organic solution, the solution layer was separated, the aqueous solution layer was removed, and then water was added again. After washing and separating the layers again, the aqueous layer is removed.

Such washing is repeated 2 to 3 times to adjust the pH of the organic solution layer to 7
And collect the organic solution layer. After that, n-heptane 3 is added thereto and stirred to prepare a uniform solution.

On the other hand, put pure water into another closed container equipped with a condenser and heat it at 65 ° C with stirring to inject and evaporate the mixed solution of the aromatic polyester product prepared previously. Methylene is condensed in a condenser and collected in another container.

When the injection of the mixed solution of the product is finished, the mixed solution of water and n-heptane in which the product is deposited is heated to 80 ° C. to completely remove the remaining methylene chloride, and again. After cooling to room temperature, the product is separated from the mixed solution of water and n-heptane by filtration.

The mixed solution thus separated is layer-separated into water and n-heptane to recover n-heptane.

On the other hand, the precipitate collected by filtration in the form of flakes was washed again with pure water while stirring, then filtered again to be recovered, and vacuum dried at 140 ° C. for 6 hours.

As a result of measuring the logarithmic viscosity of this product by the method described above,
The polymerization degree was 0.63 d / g, which was sufficient for use as a molded product, and no unreacted monomer was confirmed as a result of gel filtration chromatography measurement.

In addition, a graduated cylinder is used to produce a flaky product 100 m
Then, the weight was measured and found to be 29 g.

Example 2 The flakes of the aromatic polyester product produced in Example 1 were pelletized and then measured for whiteness (L value) and yellowness (b value) with a Hunter color meter.
And was 8.

Example 3 A pellet of the aromatic polyester product prepared in Example 2 was injection-molded to produce a tensile strength test piece and a flat plate test piece having a thickness of 2 mm, and the tensile strength and the elongation were measured.
/ Cm ² and 47% showed practically sufficient mechanical performance, and the total light transmittance of the flat plate sample was measured and found to be 87%.

Comparative Example 1 An organic solution of the product was prepared and recovered in the same manner as in Example 1, but n-heptane was not added to the organic solution of the product, and the organic solution of the product was injected into warm water and recovered. Flake
The weight of 100 m was measured and found to be 2.7 g.

Comparative Example 2 The flakes of the aromatic polyester product produced in Comparative Example 1 were pelletized, and then the whiteness (L value) and the yellowness (b value) were measured by a Hunter color measuring machine.
And was 19.

Comparative Example 3 The pellet of Comparative Example 2 was molded in the same manner as in Example 3 and the total light transmittance was measured to be 82%.

As seen in the above Examples and Comparative Examples, the non-solvent of the product replaceable with the organic solvent of the aromatic polyester product used during the interfacial polymerization according to the method of the present invention was added to the organic solution of the product to obtain a uniform solution. When a mixed solution of the following is prepared and sprayed into another container into hot water under heating and stirring to recover the precipitated product, the bulk of the product is reduced and workability is improved. It was found that the hue and the transparency were improved.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Han San-jiu Seoul, Republic of Korea. Kannamugu. Gepodon. Hiyunde Apartment 102-606 (56) Reference JP 54-74894 (JP, A) JP 48-55990 (JP, A) JP 61-57329 (JP, B2) JP 60-43855 (JP, B2) JP 60-39087 (JP, B2)

Claims (3)

[Claims] 1. When recovering an aromatic polyester product from an organic solution of an aromatic polyester product produced by interfacial polymerization, the organic solution of the product and an organic solvent of the product used in the interfacial polymerization are used in the organic solution of the product. After mixing the non-solvent of the displaceable product, the organic solvent used in the above polymerization was evaporated and recovered by charging or spraying it with warm water in a separate container while heating it in a separate container. A method for recovering an aromatic polyester product, characterized in that the product is precipitated from warm water and recovered by filtration. 2. The method for recovering an aromatic polyester product according to claim 1, wherein methylene chloride is used as an organic solvent for the product. 3. The aromatic polyester product according to claim 1, wherein a hydrocarbon having 6 to 12 carbon atoms is used as a non-solvent for the product which can be replaced with the organic solvent for the product. Recovery method.