JPH07228679A - Production of aromatic polycarbonate - Google Patents

Abstract

PURPOSE:To obtain the subject substance having an excellent color tone stably by subjecting phosgene having removed hexachloroethane to a content of <=a specific value and an aromatic dihydroxy compound to interfacial polycondensation. CONSTITUTION:Phosgene having <=5ppm hexachloroethane content and an aromatic dihydroxy compound (preferably bisphenol A) are subjected to interfacial polycondensation to give the objective polycarbonate.

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, from the aromatic dihydroxy compound and phosgene, water,
When an aromatic polycarbonate is produced by an interfacial polycondensation method using an organic solvent, an alkali metal, a molecular weight modifier, a polymerization catalyst, etc., trace amounts of impurities contained in each raw material are mixed into the product to deteriorate the color tone Not a few things. Therefore, it is necessary to give sufficient consideration to the quality of raw materials.

Among them, a trace amount of impurities contained in phosgene, which remains in the obtained aromatic polycarbonate, has a problem of affecting the color tone. For example, in JP-A-1-275630, phosgene is produced by setting the amount of a sulfur-containing compound contained in carbon monoxide, which is a raw material of phosgene, to 30 ppm (volume) or less, and the phosgene is used to produce an aromatic polycarbonate. Is shown. The sulfur-containing compound derived from this raw material is
In the polymerization reaction, it is said that the reproducibility of the molecular weight of the obtained aromatic polycarbonate is disturbed and the color tone is deteriorated. Further, JP-A-62-297320 discloses a method for producing an aromatic polycarbonate using phosgene having a carbon tetrachloride concentration of 200 ppm or less as a raw material phosgene. When this carbon tetrachloride is mixed in the product, acid components are generated by pelletizing and heating during molding, which corrode the mold of the molding machine, and the color tone of the resulting aromatic polycarbonate molded product deteriorates. Is said to cause the deterioration of quality.

However, even when an aromatic polycarbonate is produced by using phosgene containing almost no impurities containing a sulfur component and having a carbon tetrachloride concentration of 200 ppm or less, which satisfies the above-mentioned conditions of the prior art, The color tone of the obtained product was sometimes unfavorable.
That is, it was considered that unknown components still exist as impurities in phosgene, which hinders the production of aromatic polycarbonate having good reproducibility and excellent color tone.

[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. The purpose is to

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a trace amount of hexachloroethane is present in phosgene, and can be obtained from phosgene containing this hexachloroethane. The aromatic polycarbonate has a poor color tone, and it has been found that the color tone of the obtained aromatic polycarbonate is improved by removing the aromatic polycarbonate from the phosgene to a specific value or less, and the present invention has been completed. That is, the present invention is a method for producing an aromatic polycarbonate by an interfacial polycondensation method from at least one aromatic dihydroxy compound and phosgene, wherein the content of hexachloroethane as the raw material phosgene is 5 ppm.
A method for producing an aromatic polycarbonate, which comprises using the following phosgene.

The present invention will be described in detail below. In the present invention, an aqueous solution containing an aromatic dihydroxy compound, phosgene, and an organic solvent are used. The aqueous solution containing an aromatic dihydroxy compound used in the present invention comprises at least one aromatic dihydroxy compound, an alkali metal or alkaline earth metal base, water, a molecular weight modifier, a polymerization catalyst, and optionally a branching agent.

The aromatic dihydroxy compound used in the present invention is a compound represented by the following formula (I) or (II). HO-Ar1-X-Ar2-OH (I) HO-Ar3-OH (II) In the above formula, Ar1, Ar2 and Ar3 each have a monocyclic divalent aromatic group, that is, a phenylene group or a substituent. Is a substituted phenylene group, the substituent,
Examples thereof include a halogen atom, a nitro group, an alkyl group, a cycloalkyl group, an alkenyl group, a hydrocarbon group such as an aralkyl group or an aryl group, and an alkoxy group.

Ar1 and Ar2 are both p-phenylene group, m-phenylene group or o-phenylene group, or one is p-phenylene group and the other is m-phenylene group or o-phenylene group. Are preferred, and it is particularly preferred that both Ar1 and Ar2 are p-phenylene groups.

X is a linking group connecting Ar1 and Ar2, and is a single bond or a divalent hydrocarbon group, and
O -, - S -, - SO -, - SO 2 -, - it may be a group containing atoms other than carbon and hydrogen CO- like. The divalent hydrocarbon group means a saturated hydrocarbon group such as methylene,
Examples thereof include alkylidene groups such as ethylene, 2,2-propylidene, cyclohexylidene, and cyclohexylidene having a substituent, but groups substituted with an aryl group are also included, and aromatic groups and other unsaturated groups are also included. It may be a hydrocarbon group containing the hydrocarbon group of.

Specific examples of the aromatic dihydroxy compound include bis (4-hydroxyphenyl) methane and 1,1-
Bis (4'-hydroxyphenyl) ethane, 1,2-bis (4'-hydroxyphenyl) ethane, bis (4-hydroxyphenyl) phenylmethane, bis (4-hydroxyphenyl) diphenylmethane, bis (4-hydroxyphenyl) -1-naphthylmethane, 1,1-bis (4
′ -Hydroxyphenyl) -1-phenylethane, 2,
2-bis (4'-hydroxyphenyl) propane ["bisphenol A"], 2- (4'-hydroxyphenyl) -2- (3'-hydroxyphenyl) propane,
2,2-bis (4'-hydroxyphenyl) butane,
1,1-bis (4′-hydroxyphenyl) isobutane, 2,2-bis (4′-hydroxyphenyl) octane, 2,2-bis (3′-methyl-4′-hydroxyphenyl) propane, 2,2 -Bis (3'-ethyl-4 '
-Hydroxyphenyl) propane, 2,2-bis (3 '
-N-propyl-4'-hydroxyphenyl) propane, 2,2-bis (3'-isopropyl-4'-hydroxyphenyl) propane, 2,2-bis (3'-sec)
-Butyl-4'-hydroxyphenyl) propane, 2,
2-bis (3′-tert-butyl-4′-hydroxyphenyl) propane, 2,2-bis (3′-cyclohexyl-4′-hydroxyphenyl) propane, 2,2-
Bis (3′-allyl-4′-hydroxyphenyl) propane, 2,2-bis (3′-methoxy-4′-hydroxyphenyl) propane, 2,2-bis (3 ′, 5′-dimethyl-4 ′) -Hydroxyphenyl) propane, 2,
2-bis (2 ', 3', 5 ', 6'-tetramethyl-4
′ -Hydroxyphenyl) propane, 2,2-bis (3
′ -Chloro-4′-hydroxyphenyl) propane,
2,2-bis (3 ', 5'-dichloro-4'-hydroxyphenyl) propane, 2,2-bis (3'-bromo-)
4'-hydroxyphenyl) propane, 2,2-bis (3 ', 5'-dibromo-4'-hydroxyphenyl)
Propane, 2,2-bis (2 ', 6'-dibromo-3
′, 5′-Dimethyl-4′-hydroxyphenyl) propane, bis (4-hydroxyphenyl) cyanomethane,
Bis (hydroxyaryl) alkanes such as 1-cyano-3,3-bis (4′-hydroxyphenyl) butane and 2,2-bis (4′-hydroxyphenyl) hexafluoropropane,

1,1-bis (4'-hydroxyphenyl) cyclopentane, 1,1-bis (4'-hydroxyphenyl) cyclohexane, 1,1-bis (4'-hydroxyphenyl) -3,3,5 -Bis (hydroxyaryl) cycloalkanes such as trimethylcyclohexane, 1,1-bis (4'-hydroxyphenyl) cycloheptane, 2,2-bis (4'-hydroxyphenyl) adamantane, 4,4'-dihydroxydiphenyl ether , 4,4'-dihydroxy-3,3'-dimethyldiphenyl ether, dihydroxydiaryl ethers such as ethylene glycol bis (4-hydroxyphenyl) ether, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxy-3 , 3'-Dimethyldiphenyl sulfide, etc. Roxydiaryl sulfides, 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide and other dihydroxydiaryl sulfoxides, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxy Dihydroxydiarylsulfones such as -3,3'-dimethyldiphenylsulfone, bis (4-hydroxyphenyl) ketone, bis (4
Bis (hydroxyaryl) ketones such as -hydroxy-3-methylphenyl) ketone,

Further, 6,6'-dihydroxy-3,
3,3 ′, 3′-Tetramethylspiro (bis) indane [“spirobiindanebisphenol”], trans-2,3-bis (4′-hydroxyphenyl) -2-butene, 9,9-bis (4 ′ -Hydroxyphenyl) fluorene, 3,3-bis (4′-hydroxyphenyl)-
2-butanone, 1,6-bis (4'-hydroxyphenyl) -1,6-hexanedione, 1,1-dichloro-
2,2-bis (4'-hydroxyphenyl) ethylene,
1,1-dibromo-2,2-bis (4′-hydroxyphenyl) ethylene, 1,1-dichloro-2,2-bis (5′-phenoxy-4′-hydroxyphenyl) ethylene, α, α, α ′, Α′-Tetramethyl-α, α′-
Bis (4-hydroxyphenyl) -p-xylene, α,
α, α ', α'-tetramethyl-α, α'-bis (4-
Hydroxyphenyl) -m-xylene, 4,4′-dihydroxybiphenyl and the like can be mentioned. In addition to the above aromatic dihydroxy compounds, hydroquinone, resorcin, etc. are also used. You may use these individually or in mixture of 2 or more types. The aromatic dihydroxy compound used particularly preferably in the present invention is bisphenol A.

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.

Hexachloroethane, which is a problem here as an impurity in phosgene which adversely affects the color tone of the aromatic polycarbonate, is considered to be generated by chlorination of ethane in carbon monoxide as a raw material during the production of phosgene. To be Hexachloroethane exists as a gas in the produced phosgene because of its high boiling point and its sublimability. Hexachloroethane in phosgene is separated to some extent by ordinary purification by liquefaction / evaporation, but if hexachloroethane, which remains slightly in the purified phosgene, is mixed in the aromatic polycarbonate, it should be removed almost completely by drying the product powder. As a result, the color tone deteriorates during heat treatment such as molding and pelletizing.

As a method of removing hexachloroethane from phosgene, any method such as a method of mainly utilizing the boiling point difference may be used. Although it can be separated by the usual distillation method by liquefaction / evaporation as described above, purification is required to be strict, because even if a minute amount of sublimation causes contamination, it may affect the product. For example, phosgene purified by a normal distillation method is aerated in a tube filled with a filler made of a material that is not violated by phosgene under low temperature conditions that do not cause liquefaction to solidify and remove the remaining hexachloroethane. There are various methods.

[0020]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples. The value of the weight average molecular weight (Mw) used in the examples is obtained by GPC SYSTEM-11 manufactured by Showa Denko KK, using a polystyrene gel column, measured with a chloroform solvent, and obtained with an RI detector. It was calculated from polystyrene in terms of polystyrene. As for the 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. Hexachloroethane and carbon tetrachloride in phosgene were measured by gas chromatography.

Example 1 In producing an aromatic polycarbonate, phosgene was purified to remove hexachloroethane in phosgene. That is, crude phosgene (hexachloroethane: 65) obtained by reacting carbon monoxide and chlorine in activated carbon
ppm, carbon tetrachloride: 750 ppm) was liquefied by cooling to -5 ° C, and then evaporated at 30 to 35 ° C to obtain primary purified phosgene (hexachloroethane: 12 ppm,
Carbon tetrachloride: 145 ppm). This primary purified phosgene is subjected to secondary purification by passing it through a pipe having a filler and controlled at 15 ° C and having an inner diameter of 20 mm and a length of 1.5 m (hexachloroethane: 2 ppm, carbon tetrachloride: 48 p
pm) supplied to the reaction system. The aromatic polycarbonate was produced as follows. Bisphenol A 780.0
g (3.421 mol), 17.7 g (0.118 mol) of p-tertiarybutylphenol and 15.6 g of sodium hydrosulfite were charged into a reaction tank together with 4320 g of pure water to make a nitrogen atmosphere. 1368 g (caustic soda 10.26 mol) of a 30 wt% caustic soda aqueous solution was supplied thereto to dissolve bisphenol A. Further, after cooling this aqueous solution to 25 ° C., 5680 g of dichloromethane was charged. The mixture was stirred so that dichloromethane was uniformly dispersed in the system, and 406.4 g (4.105 mol) of the secondarily purified phosgene was added to the reaction system at 25 to 35 ° C. for 60 minutes. Blown in. 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. The obtained aromatic polycarbonate reached the target molecular weight at Mw = 51200. After drying this aromatic polycarbonate powder, it was pressed at 280 ° C. for 5 minutes to prepare a 1 mm thick press sheet, and the YI value measured on the press sheet was 1.
2 and the color tone was very good.

Examples 2 to 6 and Comparative Examples 1 to 9 Using the secondary refined phosgene obtained in the same manner as in Example 1,
In order to change the hexachloroethane mixed in the reaction system as shown in Table 1, hexachloroethane and carbon tetrachloride were added in respective amounts to the raw material system before phosgenation, and the following Example 1 was used.
Aromatic polycarbonate was produced by the same method as described above, and the color tone was evaluated. The results are shown in Table 1. When hexachloroethane in phosgene was 5 ppm as in Example 2, the YI value was 1.2 and the color tone was good as in the case of Example 1, but as in Comparative Examples 1 to 3, When hexachloroethane exceeds 5ppm, YI of the sheet
Values tended to deteriorate.

[0023]

[Table 1]

[0024]

Industrial Applicability As in the present invention, an aromatic polycarbonate is produced by using phosgene having a hexachloroethane content of 5 ppm or less in phosgene.
An aromatic polycarbonate having an excellent color tone can be stably obtained.

Front Page Continuation (72) Inventor Yukiko Mori 30 Mitsui Toatsu Chemical Co., Ltd., Asmuta-cho, Omuta City, Fukuoka Prefecture (72) Shoji Obuchi 30 Asamuda-cho, Omuta-shi, Fukuoka Prefecture Mitsui Toatsu Chemical Co., Ltd. ( 72) Inventor Masahiro Ota 30 Asmuta-cho, Omuta-shi, Fukuoka Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] 1. A method for producing an aromatic polycarbonate by an interfacial polycondensation method from at least one aromatic dihydroxy compound and phosgene, which comprises using phosgene having a content of hexachloroethane of 5 ppm or less as phosgene as a raw material. Process for producing aromatic polycarbonate.