JPS6121128A - Method for purifying aromatic polyester - Google Patents

Abstract

PURPOSE:To prepare economically a polyester capable of omitting the frequency of washing thereafter, and having more remarkably improved quality, by treating an organic solvent phase of a polyester copolymer obtained by interfacial polymerization method with an ion exchange resin in the presence of water. CONSTITUTION:An aromatic polyester copolymer solution in an organic solvent prepared by bringing an alkaline aqueous solution of a dihydric phenol into contact with a terephthaloyl dichloride and/or isophthaloyl dichloride in an organic solvent by the interfacial polymerization method is treated with an ion exchange resin in the presence of water. The treatment can be carried out while mixing an organic phase separated from the aqueous phase as much as possible after the polymerization newly with ion exchange water together with washing. Na, Cl or OH type is preferred for the ion exchange resin, and a high crosslinking degree and macroporous type are used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for purifying aromatic polyester produced by interfacial polymerization. More specifically, the present invention relates to a method for purifying an aromatic polyester obtained by polycondensing dihydric phenols with terephthalic acid dichloride and/or isophthalic acid dichloride.

[Conventional technology]

The aromatic polyester obtained from dihydric phenols and a mixture of terephthalic acid dichloride and isophthalic acid dichloride is an extremely useful resin with excellent mechanical, thermal, and electrical properties. well known. The method for producing this polymer is interfacial polycondensation method,
Solution polycondensation methods and the like are known.

Among them, the interfacial polycondensation method is an advantageous method as an industrial process because it can obtain a polymer with a high degree of polymerization at a low temperature.

A method for producing aromatic polyester copolymers by interfacial polymerization using terephthalic acid dichloride and isophthalic acid dichloride is described in J. Polymer Sci.

XL 399 pages, 1959, Special Publication No. 37-5599
No. 40-1959, etc.

That is, an alkaline aqueous solution of bisphenols and an organic solvent solution of terephthalic acid dichloride and isophthalic acid dichloride are stirred and mixed to perform a reaction.

After the reaction is complete, when stirring and mixing are stopped, the mixture separates into an aqueous phase containing inorganic salts as a main component and a cloudy, opaque organic phase containing a polymer as a main component.

This organic phase contains water in a stable emulsion that cannot be easily separated even with a centrifugal sedimentation machine. This water and the organic phase contain impurities such as alkali hydroxide, alkali chlorides, alkali salts of unreacted phenols, quaternary ammonium salts often used as polymerization catalysts, and oligomers.

When pelletized and molded while containing these impurities, hydrolysis and coloring occur, resulting in a decrease in product quality. Conventionally, in order to remove the impurities, it is washed with alkaline water, acidic water, neutral water: acidic water, neutral water or alkaline water containing methanol or acetone; methanol, acetone, etc., but it can be used especially for polymerization. Many catalysts have high solubility in the organic phase and have low cleaning efficiency (
As a result, a large number of washings are required, and a product of insufficient quality cannot be obtained.

[Problems to be Solved by the Invention] An object of the present invention is to provide an efficient method for purifying aromatic polyester without the above-mentioned problems.

[Means for solving problems]

As a result of intensive studies to achieve the above object, the present inventors have found that the quality of the aromatic polyester obtained by treating a polymer solution in an organic solvent with an ion exchange resin is improved several times, and the number of times of subsequent washing is improved. It has been discovered that it is possible to omit a small amount (or even omit it altogether) (Japanese Patent Application No. 59-036100).
We have discovered that the quality and economic efficiency of aromatic polyester can be further improved by treating an organic solvent solution of aromatic polyester copolymer with an ion exchange resin in the presence of water, and have thus arrived at the present invention.

That is, the present invention provides an organic solvent solution of an aromatic polyester copolymer produced by an interfacial polymerization method by bringing an alkaline aqueous solution of divalent phenols into contact with an organic solvent solution of terephthalic acid dichloride and/or isophthalic acid dichloride. This is a method for purifying aromatic polyester, which is characterized by treating it with an ion exchange resin in the coexistence of water.

The aromatic polyester copolymer organic solvent solution to which the present invention is applied is preferably produced by an interfacial polymerization method. This manufacturing method will be explained in detail.

The organic solvent for dissolving terephthalic acid dichloride and isophthalic acid dichloride is desirably a good solvent for the aromatic polyester to be produced, and includes chlorogenic hydrocarbons such as methylene chloride, chloroborum, and ethylene chloride, among which methylene chloride is typical. Further, other solvents can be used as long as they have the above properties.

On the other hand, divalent phenols are used in the form of an aqueous alkali solution such as caustic soda or caustic potash, or an aqueous solution prepared by dispersing and dissolving an alkali salt in water. Further, the concentration of dihydric phenols in the aqueous solution is usually in the range of 1 to 10% by weight. The alkali is used in an amount equivalent to or more than the divalent phenol.

Preferred dihydric phenols used in the present invention are those represented by the following general formula.

HO-Ar -X-Ar'-〇H (wherein, Ar, Ar'haphenylene, biphenylene,
It represents a divalent aromatic nucleus such as naphthylene, and X is Ar-
It shows a direct bond between A and r' and a bridged part such as an alkylene group, an alkylidene group, an ether group, a sulfide group, a sulfoxide group, and a sulfonyl group.

) Preferred examples of dihydric phenols represented by the above general formula include bis(4-hydroxyphenyl)methane, bis(4-hydroxy-3-methylphenyl)methane, and bis(4-hydroxy- 3,5-dichlorophenyl)methane, bis(4-hydroxyphenyl)ketone,
Bis(4-hydroxyphenyl) sulfide, bis(4-hydroxyphenyl)
-hydroxyphenyl) sulfone, 4,4'-dihydroxydiphenyl ether, 2,2-bis(4-hydroxyphenyl)propane, 212-bis(4-hydroxy-3,5-dichlorophenyl)furopane, 2,2-bis Examples include (4-hydroxy-3,5-dimethylphenyl)furopane and 2,2-bis(4-hydroxynaphthyl)propane. In addition, hydroquinone,
Divalent phenolic compounds such as phenolphthalein and 4,4'-dihydroxybiphenyl can also be mentioned as divalent phenolic compounds. These compounds can also be used in combination.

%, 2.2-bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)methane, bis(hydroxyphenyl)sulfite, etc., bis(4-hydroxyphenyl)sulpone, his(4-hydroxyphenyl) The use of a mixture with ketone, 4,4'-dihydroxybiphenyl, phenolphthalein, etc. is preferable because an aromatic polyester having well-balanced thermal and mechanical properties and processability can be obtained.

An aromatic polyester copolymer is produced by bringing the thus prepared organic solvent solution of aromatic carboxylic acid dichloride into contact with an alkaline aqueous solution of divalent phenols.

The amount relationship between the aromatic dicarboxylic acid dichloride and the bisphenols is preferably approximately equimolar. Since both solutions are not compatible with each other, they are vigorously stirred to uniformly disperse them.

In this polycondensation reaction, a catalyst is used to promote the reaction, if necessary. Examples of preferred catalysts include cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, dodecyltrimethylammonium chloride, decyltrimethylammonium bromide, octyltrimethylammonium bromide, benzyltrimethylammonium chloride, benzyltriethylammonium bromide, tetrabutylammonium chloride, triphenylmethyl Quaternary ammonium salts, quaternary phosphonium salts, quaternary arnium salts such as phosphonium chloride, triphenylmethylphosphonium iodide, cetyltributylphosphonium chloride, triphenylmethylarsonium iodide, trimethyloctylarsonium iodide ; triethylamine, benzyldimethylamine,
Examples include tertiary amines such as N,N-dimethylaniline; amine oxides such as tributylamine oxide and heptyldimethylamine oxide; and crown ethers such as 118-crown-6. These can be used alone or as a mixture of two or more. Particularly preferred catalysts include cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, dodecyltrimethylammonium chloride, benzyltrimethylammonium chloride, and cetyltributylphosphonium chloride.

The amount of catalyst used depends on the type of catalyst,
Although it varies depending on the type of reaction raw materials, composition, reaction conditions, etc., 0.00
A range of 0.01 to 10% is suitable. When using a catalyst, if the amount used is less than the above range, the reaction promoting effect as a catalyst will not be observed at all, and if the amount exceeds the above range, operations such as separation and washing of the produced copolymer will be extremely difficult. Therefore, favorable results cannot be obtained.

Furthermore, various stabilizers may be added to the reaction system for the purpose of controlling the molecular weight and stability of the resulting copolymer, improving stability, and preventing coloration.

Examples of monohydric phenols and alcohols that can be used include phenol, 0-phenylphenol, p-phenylphenol, β-naphthol, p-cumylphenol, m-cumylphenol, and pt-butylphenol. ,
2.6-dimethylphenol, isopropyl alcohol, t-butyl alcohol, n-decyl alcohol, n-
Octyl alcohol, m-cresol, 0-cresol.

Examples include 2,6-di-t-butyl-4-methylphenol and fluorine-substituted aliphatic alcohol.

Examples of various stabilizers include phosphorous acid, diethyl phosphite, diphenyl phosphite, triethyl phosphite,
Tricresyl phosphite, trioctyl phosphite, tridecyl phosphite, 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-5
-Ethylphenyl)benzotriazole, pyrogallol, organic tin mercaptide compounds, sodium dithionite, pholyphenylene, active anthracene, lower polyesters of bisphenols, phosphorous acid obtained by the reaction of bisphenols or dialcohols with phosphorus trichloride Examples include triester polymers. These can generally be present in the polymer in an amount of 0.01 to 5% by weight.

The polymerization temperature is preferably in the range of -10 to 50°C, but particularly good results can be obtained in the range of 0 to 30°C.

The polymerization reaction proceeds quickly and usually takes 1 to 5 hours.

After the end of the above-mentioned time period, stirring and mixing is stopped, and the mixture is separated into an organic solvent phase containing the produced aromatic polyester copolymer as a main component and an aqueous solution phase containing a number of by-produced inorganic salts as a main component.

In the present invention, this separated organic solvent phase is treated with a cation exchange resin and/or an anion exchange resin in the presence of freshly added water.

If the aqueous phase is treated with an ion exchange resin without separating it after polymerization, the amount of NaCl and impurities contained in the aqueous phase will be large, which will contaminate the interior of the resin, and the ion exchange resin will soon break through, which is not preferable.

After polymerization, ion exchange water is added to the organic phase from which the aqueous phase has been separated as much as possible, and the ion exchange resin treatment is performed while mixing.

The water used here can be used for washing or washing, and there is no problem even if it contains methanol, acetone, etc.

The cation exchange resin used here is H type or Na type, and the anion exchange resin is CI! type or OH type is preferred.

Addition of water involves adding 1 vol of ion-exchanged water to the polymer solution.
l! % to 300 vo1% preferably 10 vot!
0;.

This is done by adding 150 vol.

The treatment method may be either a batch method or a continuous method (column).

In the case of a batch method, ion exchange water, polymer solution, and ion exchange resin are placed in a stirring tank and stirred.

In the case of a continuous system, water and a polymer solution are placed in a stirring tank and are passed through an ion exchange resin column while being stirred.

Alternatively, the water and polymer solution are mixed with a static mixer or the like and passed through an ion exchange resin column.

In this case, the mixing is preferably carried out under conditions where water is the continuous phase and the polymer solution is the emulsified dispersed phase.
There is no problem even if the polymer solution is the continuous phase and water is the dispersed phase.

The inside of the ion exchange resin layer is also preferably treated with water as a continuous phase and the polymer solution as an emulsified dispersed phase, but the reverse may be used without any problem.

When passing liquid through the column, the amount of liquid passing is 5v=i~50hr''
``Preferably, it is 5 to 30 hr-''.

Ion exchange resins include ion exchange resins, ion exchange membranes, etc., and ion exchange resins with a high crosslinking degree and macroporous type are particularly preferred, but other types with a low crosslinking degree or gel type may also have sufficient effects. can get. Any ordinary ion exchange resin can be used without any problem for the purpose of the present invention, and particularly preferred ion exchange resins include Revachit 5P112.5P120 and Diaion PK.
Cation exchange resins such as 220, PK228, Amberlite 200C, Amberlys l-15 (all trademarks), Nichibi's ion exchange resin, Revachit MP5
00, MP 600, Diaion PA 316, PA
318, PA416, PA, 418, Amberlight I
Anion exchange resins such as RA402 and IRA458 (all of the above are trademarks) can be exemplified.

Even when these resins are used in the presence of a water valve, they are effective in purifying the aromatic polyester organic phase, but the exchange rate is low and the through-flow exchange capacity is low.

In the purification method of the present invention, the ion exchange rate is increased, the catalyst concentration at the outlet of the ion exchange column is lowered, and the flow-through exchange capacity is significantly increased by adding new water and coexisting water. In addition, clogging of the pores in the resin by the polymer is reduced, regeneration is easy, and the life of the resin is significantly improved.

In addition, not only the catalyst but also NaCl and other ionic impurities are removed, improving quality.

Therefore, quality, operability, and economy are significantly improved.

The purification method of the present invention includes purification using only the above-mentioned ion exchange resin, as well as activated carbon, silica gel, activated clay, etc.
Purification using molecular sheep or the like can be used in combination.

These treatments may be carried out before or after the ion exchange resin treatment or during the ion exchange resin treatment (or they may be mixed with the ion exchange resin and treated simultaneously).

It is desirable that the copolymer solution to which the method of the present invention is applied has an aromatic polyester copolymer dissolved therein at a concentration in the range of 5 to 35% by weight, preferably 10 to 25% by weight.

The aromatic polyester copolymer solution purified by the method of the present invention can be directly isolated by the method described below to obtain a product of good quality. , an organic solvent such as acetone, a mixed solvent of water and an organic solvent, or the like. Particularly preferred.

Although washing is performed using water, any method of mixing and washing the polymer solution and water may be used as long as it provides an apparently uniform emulsion. When water is used, the larger the amount of water, the better the mixing ratio, but it is preferable that the ratio of water to aromatic polyester copolymer solution is 1=2 to 2.1.

The polymer is isolated from the organic solvent solution thus treated. Isolation methods include ethanol, methanol,
A method in which the copolymer is precipitated by adding a non-solvent for aromatic polyester copolymers such as isopropanol or acetone, and a method in which the copolymer is precipitated by contacting with hot water or steam, the organic solvent is distilled off along with the steam, and the polymer is slurried in water. A method of distilling off the organic solvent from a solution of a polymer in an organic solvent by heating and reducing pressure, and a method of concentrating the solution of a polymer in an organic solvent to increase the polymer concentration, forming a gel, and pulverizing this. Any of these can be used.

The aromatic polyester copolymer thus isolated and obtained is further subjected to washing, drying, etc., if necessary, and then used for producing molded articles.

By the method of the present invention, an aromatic polyester copolymer with significantly improved heat resistance, cranking resistance, creep resistance, etc. can be obtained.

The aromatic polyester copolymer obtained by the method of the present invention is put to practical use by press molding, injection molding, or extrusion molding. Note that this molded product is of good quality, with less coloring and no silvering phenomenon compared to conventional molded products.

Note that the purification method of the present invention can be applied by dissolving aromatic polyester produced by other methods in a solvent.

〔Example〕

The present invention will be explained below with reference to Examples.

Note that the logarithmic viscosity ηinh in the examples was measured in a phenol/tetrachloroethane ('60/40 v/v) mixed solvent.

Example 1 2.08 kg of terephthalic acid dichloride and 2.08 kg of isophthalic acid dichloride IJ were dissolved in 60% methylene chloride = 17-, on the other hand, 2.283 kg of 2,2-bis(4-hydroxyphenyl)propane and bis (4-hydroxyphenyl)sulfone 2.503 to 9, caustic soda 1.744
80 tons of aqueous solution containing kg! dissolved in catalytic cetyl) I
While 0.01 kg of J methyl ammonium promide was added and stirred, the above methylene chloride solution was added and stirred vigorously. Concentrated hydrochloric acid 0.33 k+ after 180 minutes
+ was added and stirring was stopped. Organic phase 60j obtained by static separation? 60 J/h, ion exchange water 901! /h
Static mixer (manufactured by Noritake, inner diameter 8 + lll)
1124 element), and further passed through a tower (abbreviated as K tower) filled with a cation exchange resin (Levacit 5P112H type 7.54') at 5 V = 20 hr-' and allowed to stand for separation. The lower layer polymer solution was heated to 120I! The mixture was mixed with ion-exchanged water, washed with stirring for 1 hour, and separated by standing. This washing operation was repeated twice.

The obtained washed solution was dropped into 1301 methanol being stirred to precipitate the polymer.

After filtering the polymer with a centrifuge, washing with methanol and drying (drying under reduced pressure at 150°C for 5 hours), = 18
= 7 kg of powder was obtained.

This dry powder was processed using a 25 mm diameter extruder manufactured by Koan Han, at a die temperature of 335°C and an extrusion speed of 3.5 kn/h.
' and made into pellets. The obtained pellets were colorless and transparent.

The pellets were dried at 150°C for 2 hours, and then injection molded using Arburg injection molding equipment.
Barrel temperature 370℃, mold temperature 150℃, injection pressure 11
00ko/c+#G) to obtain a transparent and uncolored molded product.

Example 2 The same procedure as in Example 1 was carried out, except that after passing through the K tower, the liquid was passed through a tower (A tower) packed with an anion exchange resin (Levachit MP500OH type 7.51). A powder of a group polyester copolymer was obtained. Pelletization and molding were performed using this powder.

Example 3 In Example 1, 2.2-
An aromatic polyester copolymer powder was obtained in the same manner as in Example 1, except that 9 was used for bis(4-hydroxyphenyl)propane 4.566.

The obtained powder was pelletized and molded.

Comparative Example 1 In Example 1, instead of performing ion exchange resin treatment and water washing, a solution of an aromatic polyester copolymer and a methanol water mixture of 201 methanol and 10 r of ion exchange water were mixed, stirred for 1 hour, and then allowed to stand still. An aromatic polyester copolymer powder was obtained in the same manner as in Example 1, except that the separation operation was performed five times. The obtained powder was pelletized and molded.

Comparative Example 2 Powder of an aromatic polyester copolymer was prepared in the same manner as in Example 1, except that the organic phase 60/, which had been left to stand after polymerization and was separated, was directly passed through the column at 5 V = 5 hr-'. Obtained. The obtained powder was pelletized and molded.

The remaining amount of sodium ions and catalyst in the aromatic polyester copolymer powder in Examples 1 to 3 and Comparative Examples 1 to 2, the color tone of the molded product and the logarithmic viscosity ηinh of the resin when molded, the molded product Tensile strength (ASTM D-6
38), breaking elongation of molded product (ASTM D-638),
The impact strength (ASTMD-256) of the molded product and the long-term heat resistance (time for the original tensile strength to be halved when left at 2oO<0>C for a long period of time) of the molded product were measured.

These results are shown in Table-1.

Note that sodium ion analysis was performed by atomic absorption spectrometry, and catalyst analysis was performed using orange ■ method.

In addition, the color tone of the molded product was visually determined, and the color tone was rated ◎ if it was almost the same as that of the pellets, ○ if it was slightly different, △ if it was clearly changed, and × if the color change was severe.

The flow-through exchange capacity is defined as the catalyst concentration at the outlet of the cation exchange resin column i
Table 2 shows a comparison of Example 1 and Comparative Example 2, expressed in exchange capacity until 0 ppm/organic phase.

Table 2 *) Utilization rate - flow-through exchange capacity/total exchange capacity As seen in No. 1, the results are good, and the present invention has great industrial value.

Claims (1)

[Claims] 1. Contact an alkaline aqueous solution of divalent phenols with an organic solvent solution of terephthalic acid dichloride and/or isophthalic acid dichloride to form an organic solvent solution of an aromatic polyester copolymer produced by an interfacial polymerization method. A method for purifying aromatic polyester, characterized by treating it with an ion exchange resin in the presence of an ion exchange resin.