JPH07179595A - Production of aromatic polycarbonate - Google Patents

Abstract

PURPOSE:To improve the color tone of an aromatic polycarbonate useful as an engineering plastic by lowering the content of impurities in bisphenol A to <= a specific value. CONSTITUTION:A method for producing an aromatic polycarbonate comprises dissolving a bisphenol A, i.e., 2,2-bis(4-hydroxyphenyl)propane, lowered in the total content of the compounds of formula I and/or formula II to <60ppm in an alkali(ne earth) metal base aqueous solution, and subsequently reacting the aqueous solution with a carbonyl halide compound in the presence of a polymerization catalyst, a mol.wt.-controlling agent and an organic solvent.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an aromatic polycarbonate. More specifically, the present invention relates to a method for producing an aromatic polycarbonate having an excellent color tone, which is a method for producing an aromatic polycarbonate by an interfacial polycondensation method using an aromatic dihydroxy compound and phosgene.

[0002]

2. Description of the Related Art Aromatic polycarbonates are excellent in high strength, high rigidity, heat resistance and impact resistance, and are also excellent in transparency, weather resistance, dimensional stability, electrical properties, etc. as engineering plastics in many fields. It is used.
In particular, aromatic polycarbonate has wide application as a glass substitute because of its excellent transparency and impact resistance. The color tone of the aromatic polycarbonate used for such applications has a very important meaning in quality evaluation. However, when an aromatic polycarbonate is produced from an aromatic dihydroxy compound and a carbonyl halide compound by an interfacial polycondensation method using water, an organic solvent, an alkali metal, a molecular weight modifier, a polymerization catalyst, etc., it is included in each raw material. It is not uncommon for trace amounts of impurities to enter the product to deteriorate the color tone. Therefore, it is necessary to give sufficient consideration to the quality of raw materials.

Conventionally, 2,2-bis (4-hydroxyphenyl) propane (hereinafter abbreviated as bisphenol A) is used as an aromatic polycarbonate resin as a hydroxy compound, and an alkali metal or alkaline earth metal base aqueous solution of bisphenol A is used. A carbonyl halide compound,
When produced by reacting in the presence of a polymerization catalyst, a molecular weight regulator, and an organic solvent, the purity of bisphenol A, which is the main raw material, is significant in the quality of the polymerization reaction and the polymer (including oligomer) that is the product. Known to have an impact. When the crude bisphenol A is used for the polymerization, the produced polymer is colored yellow or red, or the heat resistance becomes insufficient, and in extreme cases, the polymerization reaction does not proceed to a desired degree of polymerization and the production becomes impossible. Product value is lost due to marked quality defects. Since these defective phenomena do not occur at all when bisphenol A having an extremely high purity is used, trace impurities contained in bisphenol A interfere with the polymerization reaction, cause coloration of the produced polymer, and lower heat resistance. It is considered that It is a known fact to use high-purity bisphenol A in the production of aromatic polycarbonates. However, the content of impurities has not been clarified.

Conventionally, several purification methods and production methods have been proposed for the purpose of purifying bisphenol A to obtain a good aromatic polycarbonate. For example, a method in which bisphenol A is dissolved in methanol and adsorbed and purified with activated carbon and then bisphenol A is recovered by crystallization or reprecipitation with water to produce an aromatic polycarbonate (Japanese Patent Publication No. 41-17478), 1.5 to bisphenol A
~ 5 parts by weight of 2,2,4-trimethylpentane and a mixed solvent of aromatic hydrocarbons are contacted and purified by solid extraction (Japanese Patent Publication No. 49-39669), similarly bisphenol A to methylene chloride, A method of extracting and purifying by contacting ethylene chloride and trichlorethylene (Japanese Patent Publication No. 47-10384), a method of dissolving bisphenol A in ethylene glycol, and then adding a certain amount of water to precipitate and recover bisphenol A (USP.
No. 3,919,330), bisphenol A caustic alkali and water obtained by mixing or contacting a water-insoluble or sparingly water-soluble organic solvent with a mixture of bisphenol A, caustic alkali and water, and separating the organic solvent. Method of using the mixed solution of the above as a reaction raw material liquid
No. 7), a method of separating bisphenol A from excess phenol and low-boiling substances immediately after production in an evaporator at a temperature of 100 to 300 ° C. and a pressure of 0.5 to 500 mbar (Japanese Patent Publication No. 63-39611). Etc. However, in any of the methods, there is no mention of the effect of each impurity, or the amount that can affect each impurity.

[0005]

DISCLOSURE OF THE INVENTION The present invention is a method for producing an aromatic polycarbonate by an interfacial polycondensation method using an aromatic dihydroxy compound and phosgene, and produces an aromatic polycarbonate having a stable color tone. This is an issue.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that bisphenol A contains a small amount of a compound represented by the formula (1) and / or the formula (2). The aromatic polycarbonate obtained from bisphenol A containing these impurities has a poor color tone, and the color tone of the aromatic polycarbonate obtained is improved by removing them from the bisphenol A below a specific value. Therefore, the present invention has been completed.

That is, according to the present invention, when an aromatic polycarbonate is produced from bisphenol A as a main raw material, among the several kinds of impurities contained in bisphenol A, the formula (1) and / or the formula (2) are particularly preferable.

[0008]

[Chemical 3]

[0009]

[Chemical 4]

The total content of compounds represented by is 60
A method for producing an aromatic polycarbonate, which comprises using less than ppm of bisphenol A.

The present invention will be described in detail below. The bisphenol A used in the present invention is produced by a known method, for example, phenol and acetone in the presence of an acidic catalyst. In this production, a cocatalyst such as a sulfur compound may be added.

In the above production method, bisphenol A is, of course, produced in high yield. The produced bisphenol A is phenol, 4-isopropylphenol (hereinafter, PIP), 2- (2-hydroxyphenyl). -2- (4-hydroxyphenyl) pyropan (hereinafter OP-BPA), 2,4-bis (4-hydroxyphenyl) -4-methyl-1-pentene (hereinafter PIPE
LD1), 2,4-bis (4-hydroxyphenyl)
-4-Methyl-2-pentene (hereinafter PIPE LD
2), 1,1,3-trimethyl-3- (4-hydroxyphenyl) -indan-5-ol (hereinafter PIPE
CD), PIPE CD isomer (hereinafter PIPE
CDI), 2,4-bis (α, α-dimethyl-4-hydroxybenzyl) phenol (hereinafter, BPX-1),
2,2,4-Trimethyl-4- (4-hydroxyphenyl) chroman (hereinafter COD), 2,4,4-trimethyl-2- (4-hydroxyphenyl) chroman (p-F
lavan), 2,2,4-trimethyl-4- (4-hydroxyphenyl) -6- (α, α-dimethyl-4-hydroxybenzyl) chroman (hereinafter, BPX-2) and the like.

When such bisphenol A is used as a raw material for an aromatic polycarbonate, these impurities adversely affect the molecular weight, the molecular weight distribution, and the color tone of the aromatic polycarbonate produced, so that there is a problem in purity. Therefore, when these are used as raw materials, known purification methods, for example, those purified by combining various purification methods such as distillation, extraction, recrystallization and stripping are used. Among the above impurities, PIPE LD1 represented by the formula (1) and / or PIPE LD2 represented by the formula (2) have a large influence on the physical properties of the aromatic polycarbonate, particularly the color tone. PIP in raw material bisphenol A
The content of E LD1 and / or PIPE LD2 becomes a problem.

In the present invention, bisphenol A whose total content of PIPE LD1 and / or PIPE LD2 is less than 60 ppm by weight based on bisphenol A is used as a raw material. PIPE in raw bisphenol A
The total content of LD1 and / or PIPELD2 is 60
When an aromatic polycarbonate is produced using bisphenol A in an amount of ppm by weight or more as a raw material, the color tone of the aromatic polycarbonate produced is significantly deteriorated.

The alkali metal or alkaline earth metal base (hereinafter abbreviated as base) used in the present invention is an alkali metal or alkaline earth metal hydroxide such as sodium hydroxide, potassium hydroxide or calcium hydroxide. From the viewpoint of easy availability, sodium hydroxide and potassium hydroxide are preferable, and sodium hydroxide is particularly preferable.

The molecular weight modifier (also referred to as a terminal blocking agent) used in the present invention is for adjusting the final molecular weight in the process of producing an aromatic polycarbonate. Usually, an aromatic monohydroxy compound is used. Examples of the aromatic monohydroxy compound include phenol, p-tertiarybutylphenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-.
Ethylphenol, p-ethylphenol, o-cumylphenol, m-cumylphenol, p-cumylphenol, o-cyclohexylphenol, m-cyclohexylphenol, p-cyclohexylphenol, o-
Octylphenol, m-octylphenol, p-octylphenol, o-nonylphenol, m-nonylphenol, p-nonylphenol, o-methoxyphenol, m-methoxyphenol, p-methoxyphenol, o-chlorophenol, m-chlorophenol,
Examples include p-chlorophenol, o-bromophenol, m-bromophenol, p-bromophenol, pentabromophenol, pentachlorophenol, β-naphthol and α-naphthol. These may be used alone or in combination of two or more. Phenol or p-tert-butylphenol is preferable because of easy availability.

The polymerization catalyst used in the present invention is a tertiary amine,
Examples thereof include quaternary ammonium salts, tertiary phosphines, quaternary phosphonium salts, nitrogen-containing heterocyclic compounds and salts thereof, imino ethers and salts thereof, and compounds having an amide group. Preferably, it is a trialkylamine which is a tertiary amine, more preferably on the carbon atom at the 1-position and 2-position such as triethylamine, tri-n-propylamine, diethyl-n-propylamine, tri-n-butylamine and the like. Is a trialkylamine having an alkyl group of C1 to C4 without branching. Triethylamine is particularly preferable in terms of easy availability and excellent catalytic effect.

Any organic solvent can be used as long as it is substantially insoluble in water, inert to the reaction, and capable of dissolving the aromatic polycarbonate. For example, dichloromethane, chloroform, 1,2-
It is preferable to use aliphatic chlorinated compounds such as dichloroethane, 1,2-dichloroethylene, trichloroethane, tetrachloroethane, dichloropropane, or a mixture thereof. Further, an organic solvent in which an aromatic hydrocarbon such as toluene, xylene and ethylbenzene, an aliphatic hydrocarbon such as hexane, heptane and cyclohexane are mixed with chlorinated hydrocarbons and a mixture thereof may be used. Particularly preferred is dichloromethane. Further, in the present invention, the recovery solvent produced when the aromatic polycarbonate produced by the method of the present invention is recovered can be used as it is or as a mixture with a new organic solvent.

[0019]

EXAMPLES The present invention will be described in detail with reference to the following examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In addition, the test method of the polycarbonate manufactured in Examples, Comparative Examples and the like was as follows. Weight average molecular weight (Mw): Showa Denko KK GPCSY
Using STEM-11, a polystyrene gel column was used, measurement was carried out with a chloroform solvent, and it was calculated in terms of polystyrene from the chromatogram obtained by the RI detector. Impurity content: measured by HPLC. (Unit: ppm) YI value: The value of a 1 mm thick press sheet was measured using a color difference meter manufactured by Suga Test Instruments Co., Ltd.

Example 1 Aromatic polycarbonate was produced as follows.
780.0 g (3.421 mol) of bisphenol A and p
-Tert-butylphenol 17.7 g (0.118
Mol) and sodium hydrosulfite 15.6 g
Was charged into a reaction tank together with 4320 g of pure water to make a nitrogen atmosphere. There, 1368 g of 30 wt% caustic soda solution
(Caustic soda 10.26 mol) was supplied to dissolve bisphenol A. Further, after cooling this aqueous solution to 25 ° C., 5680 g of dichloromethane was charged. 406.4 g of phosgene which was secondarily purified by stirring the mixture so that dichloromethane was uniformly dispersed in the system.
(4.105 mol) was blown in in 60 minutes while controlling the reaction system at 25 to 35 ° C. After the completion of blowing, 0.6 g of triethylamine was added and the mixture was stirred for 1 hour to terminate the polymerization. The obtained organic phase was separated from the aqueous phase, neutralized with hydrochloric acid, and washed with pure water until the electrolyte was exhausted. The organic solvent was evaporated from the organic solvent solution containing this aromatic polycarbonate to obtain a solid aromatic polycarbonate.
After drying the obtained aromatic polycarbonate powder, 280
A 1 mm thick press sheet was prepared by pressing at 5 ° C. for 5 minutes, and the YI value was measured on the press sheet. At this time, the weight average molecular weight of the aromatic polycarbonate was 51200.
The YI was 1.2, and it was a high-quality aromatic polycarbonate having good molecular weight and color tone.

Example 2 The procedure of Example 1 was repeated except that the bisphenol A described in Example 2 of Table 1 was used. The obtained polycarbonate resin had a weight average molecular weight of 5,1200 and a YI of 1.1, and was a high-quality aromatic polycarbonate having good molecular weight and good color tone.

Example 3 The same as Example 1 except that bisphenol A described in Example 3 of Table 1 was used. The obtained polycarbonate resin had a weight average molecular weight of 5,1200 and a YI of 1.2, and was a high-quality aromatic polycarbonate having good molecular weight and color tone.

Comparative Example 1 The procedure of Example 1 was repeated except that the bisphenol A described in Comparative Example 1 in Table 1 was used. The obtained polycarbonate resin had a weight average molecular weight of 5,1200 and a YI of 1.5, and the color tone deteriorated.

Comparative Example 2 PIPE L was added to bisphenol A described in Example 1 in Table 1.
Example 1 was repeated except that D1 was added in an amount of 60 ppm by weight based on bisphenol A. The obtained polycarbonate resin had a weight average molecular weight of 5,1200 and a YI of 1.3, and the color tone deteriorated.

COMPARATIVE EXAMPLE 3 PIPE L was added to bisphenol A described in Example 1 in Table 1.
Example 1 was repeated except that D1 was added in an amount of 70 ppm by weight based on bisphenol A. The obtained polycarbonate resin had a weight average molecular weight of 5,1200 and a YI of 1.4, and the color tone deteriorated.

[0026]

[Table 1]

[0027]

INDUSTRIAL APPLICABILITY As in the present invention, the amount of the compound represented by the formula (1) and / or the formula (2) among impurities in bisphenol A is less than 60 ppm.
By using the above to produce an aromatic polycarbonate, an aromatic polycarbonate having an excellent color tone can be stably obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Kuroki 30 Asmuta-cho, Omuta City, Fukuoka Prefecture Mitsui Toatsu Chemical Co., Ltd. In-house (72) Inventor Masahiro Ota 30 Asmuta-cho, Omuta-shi, Fukuoka Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] 1. A polymerization catalyst containing an aqueous solution of an alkali metal or alkaline earth metal base of 2,2-bis (4-hydroxyphenyl) propane and a carbonyl halide compound.
In producing an aromatic polycarbonate by reacting in the presence of a molecular weight modifier and an organic solvent, a compound represented by the formula (1) and / or the formula (2): [Chemical 2] A process for producing an aromatic polycarbonate, which comprises using 2,2-bis (4-hydroxyphenyl) propane having a total content of less than 60 ppm.