JPH047328A - Production of polycarbonate - Google Patents

Abstract

PURPOSE:To obtain a lowly colored high-molecular weight polycarbonate by melt-polycondensing a dihydroxy compound with a bisaryl carbonate in a reactor having an inside wall made of buffed stainless steel. CONSTITUTION:The inside wall of a stainless steel reactor is buffed with a buffing compound having a grain size of 80mum or below. A dihydroxy compound of any one of formulas I-IV (wherein R1 to R5 are each H, 1-8C linear or branched alkyl or phenyl; X is halogen, (n) is 0-4; and (m) is 1-4) is melt- polycondensed with a bisaryl carbonate at 100-300 deg.C in the presence of a transesterification catalyst (e.g. lithium borohydride) in the reactor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing polycarbonate, and more particularly to a method for producing polycarbonate that yields a high molecular weight polycarbonate with little coloring.

BACKGROUND OF THE INVENTION Polycarbonate is a general purpose engineering thermoplastic that has a wide range of uses, particularly for injection molding or as glass sheets in place of window panes.

Conventionally, interfacial polycondensation methods, transesterification methods, and the like have been applied to the production of these polycarbonates.

Although the interfacial polycondensation method is generally effective in producing polycarbonate, it has drawbacks such as the use of toxic phosgene and the fact that chlorine ions remain in the polycarbonate produced. In order to eliminate these drawbacks, a method for manufacturing polycarbonate by using liquid trichloromethyl chloroformate, which is a dimer of phosgene, instead of toxic phosgene, and carrying out an interfacial polycondensation reaction with a special dihydric phenol has been disclosed. It is disclosed in Publication No. 182336/1983. However, as a special dihydric phenol, 9
．． There is only a description of 9-bis(4-hydroxyphenyl)fluorenes. In addition, a method for obtaining polycarbonate from 2,2-bis(4-hydroxyphenyl)propane using triphosgene instead of toxic phosgene was described by ^ngeiv, Chen+ (Angehante Hemi-), 922 (1987L German Patent E344).
0141, a reaction mechanism in which phosgene is generated has also been proposed.

In the transesterification reaction, a transesterification catalyst is added to diphenyl carbonate and an aromatic dihydroxy compound, and a prepolymer is synthesized while distilling phenol under heating and reduced pressure.Finally, the prepolymer is heated to 290°C or higher under high vacuum. phenol is distilled off to obtain high molecular weight polycarbonate (U.S. Pat. No. 4,345,062).
However, unlike other engineering plastics, high-molecular-weight polycarbonate has an extremely high melt viscosity, so it requires a high temperature of 290°C or higher as a reaction condition, and a high vacuum is required to distill off phenol, which has a high boiling point. (10-'' Torr), it is difficult to industrialize from the equipment standpoint, and it is also known that residual phenol in the polycarbonate produced has an unfavorable effect on the hue and physical properties.

However, since the transesterification method can carry out the reaction by melt polycondensation and is an industrially economical method, various studies have been made. In particular, it has been suggested that the material of the reactor has an influence on product coloring. For example, as disclosed in US Pat. No. 4,383,092, product coloring can be prevented by using tantalum, nickel, or chromium as the reactor material. It is suggested that it be measured.

However, these metals are expensive and impractical to use as reactor materials.

[Means to solve the problem]

The present inventors have conducted various studies on the coloring of product resins, which is one of the problems of the transesterification method conventionally used in the production of polycarbonate, and have developed a stainless steel reactor that is versatile and can be used at low cost. As a result of intensive research,
The present invention was completed based on the discovery that colorless and transparent high molecular weight polycarbonate can be obtained by hub polishing, especially the inner wall surface of the reactor.

That is, the present invention is a method for producing polycarbonate by melt polycondensation of a divalent hydroxy compound and bisaryl carbonate by a transesterification method in the presence of a transesterification catalyst, in which a hub-polished stainless steel is used for the inner wall surface of a reaction device. The present invention provides a method for producing polycarbonate characterized by the following.

Typical examples of transesterification catalysts that can be used in the present invention include (a) catalysts similar to metal-containing catalysts such as lithium borohydride, sodium borohydride, potassium borohydride, rubidium borohydride, Cesium boron, beryllium borohydride, magnesium borohydride, calcium borohydride, strontium borohydride, barium borohydride, aluminum borohydride, titanium borohydride, tin borohydride, germanium borohydride, Tetraphenoxylithium, tetraphenoxy sodium, tetraphenoxy potassium, tetraphenoxylbidium, tetraphenoxycesium, sodium thiosulfate, beryllium oxide, magnesium oxide, tin (IV) oxide, dibutyltin oxide, beryllium hydroxide, magnesium hydroxide, germanium hydroxide , beryllium acetate, magnesium acetate, tin acetate (■), germanium acetate, lithium carbonate, sodium carbonate, potassium carbonate, beryllium carbonate, magnesium carbonate, tin carbonate (■), germanium carbonate, tin nitrate (■), germanium nitrate, Examples include antimony oxide, bismuth trimethyl carboxylate, and the like.

(b) Catalysts similar to electron-donating amine compounds include:
N,N-dimethyl-4-aminopyridine, 4-diethylaminopyridine, 4-aminopyridine, 2-aminopyridine, 2-hydroxypyridine, 2-methoxypyridine, 4-methoxypyridine, 4-hydroxypyridine, 2
-dimethylaminoimidazole, 2-methoxyimidazole, 2-mercaptoimidazole, aminoquinoline,
Examples include imidazole, 2-methylimidazole, 4-methylimidazole, diazabicyclooctane (DABCO), and the like.

Further, (C) carbonic acid, acetic acid, formic acid, nitric acid, nitrous acid, oxalic acid, fluoroboric acid, hydrofluoride, etc. of the above-mentioned electron-donating amine compounds can be mentioned.

(d) Catalysts similar to electron-donating phosphorus compounds include triethylphosphine, tri-n-propylphosphine,
Tri-isopropylphosphine, tri-n-butylphosphine, triphenylphosphine, tri-〇-dimethoxyphenylphosphine, tri-P-)lylphosphine, tri-0-)lylphosphine, tributylphosphite, triphenylphosphite, tri-p-tolylphosphite , trilotryl phosphite and the like.

Furthermore, (e) catalysts similar to borane complexes include complexes of borane and the following compounds, namely ammonia, dimethylamine, trimethylamine, triethylamine, t-
Butylamine, dimethylaniline, pyridine, dimethylaminopyridine, morpholine, piperazine, pyrrole,
Examples include complexes with tetrahydrofuran, dimethyl sulfide, tri-n-butylphosphine, triphenylphosphine, triphenylphosphite, and the like.

Furthermore, examples of the divalent hydroxy compound used in the present invention include compounds represented by the following general formulas (1) to (IV).

R4R4 R4-, R4 (wherein Rt+ Rz, R3, R4, R5 each represent a hydrogen atom, a linear or branched alkyl group having 1 to 8 carbon atoms, or a phenyl group, and X represents a halogen atom, n=o~4, -1~4.) Specifically, 2,2-bis-(4-hydroxyphenyl)
Propane, 2,2-bis-(4-hydroxyphenyl)
Butane, 2,2-bis-(4-hydroxyphenyl)-
4-methylpentane, 2,2-bis-(4-hydroxyphenyl)octane, 4,4”-dihydroxy-2,2
,2-)liphenylethane, 2,2-bis-(3,5-
dibromo-4-hydroxyphenyl)propane, 2.2
-bis-(4-human ot-3-methylphenyl)propane, 2,2-bis-(4-hydroxy-3-isopropylphenyl)propane, 2,2-bis-(4-human ot-1-cy) 3-sec, butylphenyl)propane,
2.2-bis-(3,5-dimethyl-4-hydroxyphenyl)propane, 2.2-bis-(4-hydroxy-
3-tert-butylphenyl)propane, 1.1″
-bis-(4-hydroxyphenyl)-p-diisopropylbenzene, 1.1'-bis-(4-hydroxyphenyl)-m-diisopropylbenzene, 1. ■-Bis(4-hydroxyphenyl)cyclohexane and the like are mentioned.

Furthermore, it is also possible to produce a copolymerized polycarbonate by combining two or more of these divalent hydroxy compounds.

The production method of the present invention involves melt polycondensation reaction of a divalent hydroxy compound such as bisphenol A with a bisaryl carbonate such as bisphenyl carbonate using at least one of the transesterification catalysts shown above. Implemented.

The temperature at which this reaction proceeds ranges from 100°C to about 300°C. The reaction temperature is preferably 130
It ranges from ℃ to 280℃. If the reaction temperature is less than 130°C, the reaction rate will be slow, and if it exceeds 280°C, side reactions will likely occur.

At least one compound selected as a catalyst has a 10-1
mol to 10-' mol, preferably 10-' mol.
-2 to 10-4 moles.

If the amount of the catalyst is less than 10-' mol, the catalytic effect will be low and the polymerization rate of polycarbonate will be slow, and if the amount of the catalyst is more than 10-1 mol, the proportion of the catalyst remaining in the polycarbonate produced will be high. This leads to a decrease in physical properties.

Further, the required amount of bisaryl carbonate is equivalent to the molar amount of the divalent hydroxy compound present in the reaction system. Generally, in order to produce a high molecular weight polycarbonate, 1 mole of a carbonate compound and 1 mole of a divalent hydroxy compound must react. If bisaryl carbonate is used, 2 moles of hydroxy compound are produced by the reaction. These 2 moles of hydroxy compound are distilled out of the reaction system.

Conventionally, when polycarbonate is produced by the transesterification method using a stainless steel reaction vessel, the resulting product tends to be colored yellow or brownish.The reason for this is not clear, but metal components interact with the transesterification catalyst. This is presumed to be due to the action promoting thermal decomposition and side reactions at high temperatures.

However, in the present invention, in the production of polycarbonate, a polycarbonate resin that is colorless and transparent and has a high molecular weight can be surprisingly obtained by applying hub polishing to the inner wall surface of a stainless steel reactor, which was conventionally thought to be easily colored.

Hub polishing in the present invention refers to JISHO400-19
This refers to hub polishing or hub finishing as defined in 61, and is generally known as a method of imparting smoothness to the surface. The finishing level of hub polishing is not particularly limited, but the grain size is preferably 801 m ("200) or less (JIS R6001-1956).

In addition, examples of stainless steel include SOS 304, S
OS 304 L, SUS 316, SO331
6L, etc., but is not limited to these.

Furthermore, it is fully conceivable that the production method of the present invention may be carried out in combination with methods such as pickling the stainless steel used as the reaction device.

〔Example〕

The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 The inner wall surface of a reaction vessel made of stainless steel (SO5316) was
22.8 g of 2,2-his-(4-hydroxyphenyl)propane was added to a hub-polished reactor with a grain size of
(0.1 mol), 2-methylimidazole 0.164 g
(2Xl0-'' mol) and 21.4 g (0.1 mol) of bisphenyl carbonate were added, and after stirring at 180°C for 1 hour under a nitrogen atmosphere, the temperature was gradually increased while reducing the pressure, and finally the temperature was reduced to 0.1 Torr. A polycondensation reaction was carried out at 270°C for 1 hour, and the produced phenol was distilled off to obtain a colorless and transparent polycarbonate.

The viscosity average molecular weight (Mv) of the obtained polycarbonate was measured and found to be Mv = 26,000. Further, the hue was A38O-A580=0.112.

Here, the viscosity average molecular weight was measured by measuring the intrinsic viscosity [η] of a methylene chloride solution at 20°C using an Ubbelohde viscometer, and calculating the viscosity average molecular weight (viscosity) using the following formula.

[77] = 1.11X10-'(Mv)0・''Also, hue evaluation was performed by measuring and displaying the difference in absorbance in the 3801 Im and 580 Im wavelength regions using a UV measurement device using a 10% methylene chloride solution of polycarbonate. The larger the value, the more colored it is.

Example 2 A reaction similar to that in Example 1 was carried out using a reaction apparatus in which the inner wall surface of a reaction vessel made of stainless steel (SOS 304) was hub-polished with a grain size of 3-3, to obtain polycarbonate.

The viscosity average molecular weight (additional) of the obtained polycarbonate was measured and found to be Mv = 27,000. Moreover, the hue was A380-A380=0.106.

Example 3 A reaction apparatus in which the inner wall surface of a reaction vessel made of stainless steel (SOS 316) was hub-polished with a grain size of 3 mm was used.
Bis-(-4-hydroxyphenyl)propane 22.8
g (0.1 mol), 4-dimethylaminopyridine 0
．． 00244 g (2X 10-' mol) and 21.4 g (0.1 mol) of bisphenyl carbonate were added, and after stirring for 2 hours under a nitrogen atmosphere, a polycondensation reaction was carried out in the same manner as in Example 1, resulting in a colorless and transparent product. of polycarbonate was obtained.

The viscosity average molecular weight (Mv) of the obtained polycarbonate was measured and found to be = = 2400o. Moreover, the hue was A380-A380=0.109.

Example 4 The inner wall surface of a reaction vessel made of stainless steel (SO5304) was
22.8 g of 2,2-bis=(4-hydroxyphenyl)propane was added to a hub-polished reactor with particle size of im.
(0.1 mol), 4-dimethylaminopyridine 0.0
0244 g (2x 10-' mol) and 21.4 g (0.1 mol) of bisphenyl carbonate were added, and after stirring for 2 hours under a nitrogen atmosphere, a polycondensation reaction was carried out in the same manner as in Example 1, resulting in a colorless and transparent product. of polycarbonate was obtained.

The viscosity average molecular weight (Mv) of the obtained polycarbonate was measured and found to be MV = 26,000. Further, the hue was A380-^580=0.101.

Comparative Example 1 Polycarbonate was obtained by carrying out a polycondensation reaction in the same manner as in Example 3 without performing any treatment on the inner wall surface of a reaction vessel made of stainless steel (SO5316).

The viscosity average molecular weight (Mv) of the obtained polycarbonate was measured and found to be Mv = 18,000. Moreover, the hue was A380-A380=0.319.

Comparative Example 2 A polycondensation reaction was carried out in the same manner as in Example 4 without any treatment on the inner wall surface of a reaction vessel made of stainless steel (SO5304) to obtain polycarbonate.

The viscosity average molecular weight of the obtained polycarbonate (iii
) was measured and found to be Mv=21,000. Further, the hue was A38O-A580=0.176.

(Effects of the Invention) According to the present invention, a colorless and transparent polycarbonate having a high molecular weight and no coloring can be obtained.

Claims (1)

[Scope of Claims] 1. A method for producing polycarbonate by melt polycondensation of a divalent hydroxy compound and bisaryl carbonate by transesterification in the presence of a transesterification catalyst, in which stainless steel is hub-polished on the inner wall surface of a reaction device. A method for producing polycarbonate, characterized by using. 2 The divalent hydroxy compound has the following general formula (I), (II
), (III) or (IV). The method for producing polycarbonate according to claim 1. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(III) ▲There are mathematical formulas, chemical formulas, tables, etc.▼( IV) (In the formula, R_1, R_2, R_3, R_4, R_5 each represent a hydrogen atom, a linear or branched alkyl group having 1 to 8 carbon atoms, or a phenyl group, X represents a halogen atom, and n= 0 to 4, m = 1 to 4.)