JPH047329A - 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 stainless steel reactor having a pickled liquid-contacting part. CONSTITUTION:A stainless steel reactor is charged with hydrochloric acid of a concentration of 40-45wt.% or an aqueous nitric acid solution of a concentration of 5-15wt.%, brushed at room temperature to 50 deg.C, washed with water and dried. A dihydroxy compound of any one of formulas I-IV (wherein R1 to R5 are each H, 1-8 C 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
, 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 Angew, Chem (Angevante Hemi-
) Similar, 922 (1987), German Patent DE3440
141, 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. High molecular weight polycarbonate is obtained by distilling phenol out (U.S. Pat. No. 4,345,062).
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 (
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 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 proposed 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 a colorless and transparent high molecular weight polycarbonate can be obtained by pickling the reactor, especially the parts that come into contact with the liquid.

That is, the present invention provides a method for producing polycarbonate by melt polycondensing a divalent hydroxy compound and a bisaryl carbonate by a transesterification method in the presence of a transesterification catalyst. The present invention provides a method for producing polycarbonate characterized by using acid-washed polycarbonate.

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, lithium tetraphenoxy, sodium tetraphenoxy, potassium tetraphenoxy, tetraphenoxyrubidium, tetraphenoxycesium, sodium thiosulfate, beryllium oxide, magnesium oxide, tin(IV) oxide, dibutyltin oxide, beryllium hydroxide, hydroxide Magnesium, 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, antimony trioxide, 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.

(a) Catalysts similar to electron-donating phosphorus compounds include triethylphosphine, tri-n-propylphosphine,
triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, tri-〇-dimethoxyphenylphosphine, tri-p-)lylphosphine, trilotrylphosphine, tributylphosphine,
Examples thereof include triphenyl phosphite, tri-p-)lylphosphite, trilotrylphosphite, 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,
Tetrahydrofuran, dimethyl sulfide, tri-n-
Examples include complexes with 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).

R3 (wherein R+, Rz, Rs, Ra, and Rs 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=0-4, -=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-hydroxy-3-methylphenyl)propane, 2,2-bis-(4-hydroxy-3-isopropylphenyl)propane, 2,2-bis-(4-hydroxy-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, 1,1-bis-(4-
Examples include hydroxyphenyl)cyclohexane.

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 is carried out by subjecting a divalent hydroxy compound such as bisphenol A to a melt polycondensation reaction with a bisaryl carbonate such as bisphenyl carbonate using at least one of the transesterification catalysts shown above. Ru.

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 10-5 mol, preferably 10
-2 to 10-4 moles.

If the amount of catalyst is less than 10-5 mol, the catalytic effect will be low and the polymerization rate of polycarbonate will be slow, and if the amount of catalyst is more than 10-1 mol, the proportion of polycarbonate remaining as a catalyst will be high, so polycarbonate This leads to a decrease in the physical properties of (.

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.

Pickling in the present invention is a method in which metal is immersed in an acid solution on a boat for the purpose of scale removal or passivation treatment. In particular, when stainless steel undergoes thermal processing such as forging, hot rolling, or heat treatment, an oxide layer, or various types of scale, is formed on the surface depending on the conditions that the stainless steel has been subjected to, and the scaled metal is immersed in an acid solution. Rather than dissolving and removing scale through pickling, the iron substrate is used as an anode (+
), and an equivalent amount of hydrogen ions are precipitated on the oxide surface. It is said that the scale is mechanically removed by the hydrogen gas generated in this way.

Although the mechanism of the production method of the present invention is not necessarily clear, the interaction with the transesterification catalyst and the reaction system occurs due to the formation of a passivation film on the stainless steel or the change in the active state of the surface due to pickling. It is presumed that as a result of suppressing factors that promote thermal decomposition and side reactions at high temperatures caused by , a colorless and transparent high molecular weight polycarbonate resin without coloring can be obtained.

As the stainless steel used in the present invention, for example, SUS
304, SOS 304 L, SUS 316, S
Examples include, but are not limited to, OS 316 L.

Examples of acids used for pickling include nitric acid, sulfuric acid,
Examples include butic acid, hydrochloric acid, phosphoric acid, and the like. - An example of pickling on a boat is to immerse stainless steel in a solution containing 40 to 45% by weight of hydrochloric acid and 5 to 15% by weight of nitric acid at room temperature to 50°C, then brush and rinse with water, and then dry. Examples of methods include: Furthermore, it is fully conceivable that the stainless steel used as the reaction apparatus in the production method of the present invention may be subjected to a combination of methods such as puff polishing.

〔Example〕

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

Example 1 A reaction vessel made of stainless steel (StlS 316) was charged with 0. I
After filling with N nitric acid aqueous solution and immersing it for about 20 hours, it was washed with water and dried.

In this reaction vessel, 22.8 g (0.1 mol) of 2,2-bis-(4-hydroxyphenyl)propane, 0.164 g (2X10-" mol) of 2-methylimidazole and 21.4 g (2X10-" mol) of 2,2-bis-(4-hydroxyphenyl)propane and 21.4 After stirring at 180°C for 1 hour under a nitrogen atmosphere, the temperature was gradually increased while reducing the pressure, and finally at 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.

Viscosity average molecular weight (Mv) of the obtained polycarbonate
When measured, fiv=27,000. Moreover, the hue was A380-A380=0.108.

Here, the method for measuring the viscosity average molecular weight is to measure the intrinsic viscosity [ηj of a methylene chloride solution at 20''C using an Ubbelohde viscometer, and calculate the viscosity average molecular weight (Mv
) was calculated.

[ηl = 1.11X10-'(Mv)""Also, the hue was evaluated using a UV measuring device using a 10% methylene chloride solution of polycarbonate as 380.1111 and 580III.
The difference in absorbance in the wavelength range m is measured and displayed, and the larger the value, the more colored it is.

Example 2 A reaction vessel made of stainless steel (SO5304) was charged with 0. IN
After filling with a nitric acid aqueous solution and immersing it for about 20 hours, it was washed with water and dried.

Using this reaction vessel, the same reaction as in Example 1 was carried out,
Polycarbonate was obtained.

When the viscosity average molecular weight (Mv) of the obtained polycarbonate was measured, MV = 28000 Tear7':,
mata, hue is A38O-A580 = 0.121 tare +)
Ta.

Example 3 A reaction vessel made of stainless steel (SO5316) was charged with 0. After filling with IN nitric acid aqueous solution and immersing it for about 20 hours, it was washed with water and dried.

In this reaction vessel, 22.8 g (0.1 mol) of 2,2-bis-(4-hydroxyphenyl)propane, 0.00244 g of 4-dimethylaminopyridine (2X10
-S mol) and 21.4 g of bisphenyl carbonate (
After stirring for 2 hours under a nitrogen atmosphere, a polycondensation reaction was carried out in the same manner as in Example 1 to obtain a colorless and transparent polycarbonate.

The viscosity average molecular weight (sum) of the obtained polycarbonate was measured and found to be Mv = 25,000. Moreover, the hue was A380-A380=0.104.

Example 4 O, IN in a reaction vessel made of stainless steel (SUS 304)
After filling with a nitric acid aqueous solution and immersing it for about 20 hours, it was washed with water and dried.

In this reaction vessel, 22.8 g (0.1 mol) of 2,2-bis-(4-hydroxyphenyl)propane, 4-
Dimethylaminopyridine 0.00244 g (2X
10-S mol) and bisphenyl carbonate 21.4
After stirring for 2 hours under a nitrogen atmosphere, a polycondensation reaction was carried out in the same manner as in Example 1 to obtain a colorless and transparent polycarbonate.

The viscosity average molecular weight (sum) of the obtained polycarbonate was measured and found to be Hv=26,000. Also, the hue is A
There was 38O-A580=0.139te.

Comparative Example 1 A polycondensation reaction was carried out in the same manner as in Example 3 without any treatment on the inner wall surface of a reaction vessel made of stainless steel (SUS 316) to obtain polycarbonate.

The viscosity average molecular weight (additional) of the obtained polycarbonate was measured and found to be Mv = 20,000. Also, the hue is A380 - A380 = 0.181.

Comparative Example 1 Polycarbonate was obtained by carrying out a polycondensation reaction in the same manner as in Example 4 without performing any treatment on the inner wall surface of a reaction vessel made of stainless steel (5115304).

The viscosity average molecular weight (Mv) of the obtained polycarbonate was measured and found to be Mv = 200007. Also, hue! t A380- A380 = 0.202"i
“Atsuta.

〔Effect of the invention〕

According to the invention, High molecular weight and colorless Transparent polycarbonate can be obtained.

Claims (1)

[Claims] 1. A method for producing polycarbonate by melt polycondensing a divalent hydroxy compound and a bisaryl carbonate by a transesterification method in the presence of a transesterification catalyst, using a stainless steel reaction apparatus, A method for producing polycarbonate, characterized by using a polycarbonate that has been pickled. 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.)