JPH07233254A - Production of polycarbonate - Google Patents

Abstract

PURPOSE:To produce a polycarbonate having an excellent hue by using an apparatus prepared by subjecting a reactor made of stainless steel to a specified surface treatment. CONSTITUTION:This process for producing a polycarbonate by reacting a carbonic diester with a dihydroxyaryl compound, is characterized by using a reactor prepared by electropolishing that part of the surface of a stainless steel reactor which is to be brought into contact with the solution and immersing the electropolished reactor in a chelating agent solution. As the material for the reactor, stainless steel having a nickel content of 12wt.% or above and a chromium content of 22wt.% or above is desirable. Examples of the reactors include a polymerizer, a fractionating tower and a tank for dissolving a monomer. The electropolished surface is generally brought into contact with the chelating agent under conditions including a 0.1-10wt.% aqueous solution, a temperature of 20-90 deg.C and a time of 1-24hr.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polycarbonate by a so-called transesterification method. More specifically, the present invention relates to a method for producing a polycarbonate having a good hue, which uses a reactor in which a surface of a liquid contact portion of a reactor made of stainless steel is electrolytically polished and then immersed in a chelating agent solution.

[0002]

2. Description of the Related Art The so-called transesterification method for producing a polycarbonate by reacting a carbonic acid diester with a dihydroxyaryl compound has a relatively simple process and is superior to the phosgene method (interfacial polymerization method) in terms of operation and cost. It has been recently reviewed from the viewpoint of environmental protection that it can not only exhibit toxic properties, but does not use highly toxic phosgene and halogen-based solvents such as methylene chloride.

However, at present, the transesterification method has not been adopted as a large-scale industrial process. that is,
It is one of the main reasons that the hue of the polycarbonate produced by the conventional transesterification method is inferior to that of the phosgene method polycarbonate. There are various possible causes for the hue of the produced polycarbonate to be poor, and one of the reasons is that the material of the reactor has a great influence.

In order to solve this problem, for example, in US Pat. No. 4,383,092, the portion which comes into contact with the reaction mixture is made of a nonferrous or nonstainless special material such as tantalum, chromium or nickel. Methods have been proposed for suppressing polymer coloration. However, since these metals are expensive and are not easily processed, they have a drawback of being a very expensive reactor.

Japanese Unexamined Patent Publication (Kokai) No. 4-72327 proposes a method of using a metal material having a copper and / or nickel content of 85% by weight or more as a material of a portion which comes into contact with a reaction mixture, but it is also expensive. It has the drawback of being a device.

In addition, in JP-A-5-125168, the content of nickel and / or aluminum is 6%.
0% or more, JP-A-5-125169 has a nickel and / or molybdenum content of 60% or more, and JP-A-5-125170 has a nickel and / or carbon content of 60% or more. No. 125172 has a nickel and / or chromium content of 60% or more, and JP-A-5-125173 has a copper and / or aluminum content of 60% or more.
No. 174 proposes to use a copper and / or zinc content of 60% or more. However, looking at the examples, in each case, a special and expensive reaction apparatus for metallic materials is used, and the above-mentioned problems have not been solved yet.

[0007]

In view of the above-mentioned circumstances, the present invention does not use a reactor made of a special material in the production of a polycarbonate by a transesterification method, and has a surface specific to a reactor made of a stainless steel material. It is intended to provide a polycarbonate having an excellent hue by using a treated device.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted a multifaceted study on the influence and effect of the material of the reactor, the treatment method, etc., and as a result, surprisingly, it has been found that the conventional transesterification method produces polycarbonate. It has been discovered that even if the reactor is made of stainless steel, which has been considered unsuitable, a high-quality polycarbonate having an excellent hue can be produced by subjecting the surface of the liquid contact portion to a specific treatment.

That is, according to the present invention, when a carbonic acid diester is reacted with a dihydroxyaryl compound to produce a polycarbonate, the surface of the wetted portion of the reaction apparatus made of a stainless steel material is subjected to electrolytic polishing treatment and then a chelating agent solution. The present invention relates to a method for producing a polycarbonate using a reaction device in which the dipping treatment is performed.

Although stainless steel is used as the material of the reactor used in the present invention, stainless steel having a nickel content of 12% by weight or more and a chromium content of 22% by weight or more is particularly preferable. As a specific example, SUS
-309, SUS-309S (nickel content 12 to 1
5% by weight, chromium content 22 to 24% by weight), SUS-
310, SUS-310S (nickel content 19-22
% By weight, chromium content 24-26% by weight), SUS-3
14 (nickel content 19 to 22% by weight, chromium content 23 to 26% by weight) and the like, but are not limited thereto. In addition, the reactor in which the material of the present invention is used refers to a portion where the reaction mixture and / or the reaction by-product and / or the raw material monomer come into contact,
Examples thereof include, but are not limited to, a polymerization reactor, a fractionating tower, and a raw material monomer dissolving tank.

In the present invention, the electrolytic polishing treatment applied to the surface of the liquid contact portion of the reactor is performed by electrolyzing a material to be polished in an electrolytic solution as an anode to selectively dissolve microscopic convex portions on the surface of the material. The electrolytic solution used is
There is no limitation as long as it is used for electrolytic polishing of stainless steel, such as phosphoric acid type, sulfuric acid type, chromic acid type, perchloric acid type,
There are no particular restrictions on the processing temperature, processing time, current density, etc.

In the present invention, the electrolytic polishing treatment is followed by immersion in a chelating agent solution. As the chelating agent used at this time, any compound having a chelating ability can be used.
Examples of such chelating agents include iminodiacetic acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, 1,2-cyclohexanediaminetetraacetic acid, oxalic acid, D, L-tartaric acid, D, L-aspartic acid, salicylic acid, citric acid and salts thereof, D, L-alanine, glycine, 2-aminoethanol, dimethylglyoxime, acetylacetone, oxine, dithizone and the like can be mentioned. You may use together. As a specific treatment method, a method of bringing the surface of the reaction device subjected to electrolytic polishing into contact with the solution of these chelating agents is employed. The solvent, solution concentration, treatment temperature, treatment time and the like are not particularly limited, but generally 0.1 to 10% by weight aqueous solution, 20 to 90
The treatment is performed at a temperature of 1 to 24 hours.

The carbonic acid diester used in the present invention is a compound represented by the following general formula (1).

[Chemical 1]

Examples of the carbonic acid diester represented by the above general formula (1) include diphenyl carbonate and substituted diphenyl carbonate, dimethyl carbonate, ditolyl carbonate, di-t-butyl carbonate and the like, but diphenyl carbonate is particularly preferable. , And substituted diphenyl carbonate. You may use these carbonic acid diesters individually or in mixture of 2 or more types.

Further, with the above-mentioned carbonic acid diester, preferably 50 mol% or less, more preferably 30 mol% or less.
The dicarboxylic acid or dicarboxylic acid ester may be used in an amount of not more than mol%. As such a dicarboxylic acid or dicarboxylic acid ester, terephthalic acid, isophthalic acid, diphenyl terephthalate, diphenyl isophthalate or the like is used. When such carboxylic acid or carboxylic acid ester is used in combination with carbonic acid diester, polyester carbonate is obtained.

The dihydroxyaryl compound used in the present invention is a compound represented by the following general formula (2).

[Chemical 2]

(Where A is 2 having a carbon number of 1 to 15)
Valent hydrocarbon group, a halogen-substituted divalent hydrocarbon group or _{-S -, - S 2 -,} - SO 2 -, - SO -, - O-, and shows a -CO- divalent radicals such as, X represents a halogen atom, an alkyl group having 1 to 14 carbon atoms, an aryl group having 6 to 18 carbon atoms, an oxyalkyl group having 1 to 8 carbon atoms, and an oxyaryl group having 6 to 18 carbon atoms. m is 0 or 1
And y is an integer of 0 to 4)

The dihydroxyaryl compound represented by the general formula (2) is, for example, 2,2-bis (4-hydroxyphenyl) propane or 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane. , 2,2-
Bis (4-hydroxy-3,5-diethylphenyl) propane, 2,2-bis (4-hydroxy- (3,5-diphenyl) phenyl) propane, 2,2-bis (4-hydroxy-3,5-) Dibromophenyl) propane, 2,
2-bis (4-hydroxyphenyl) pentane, 2,
4'-dihydroxy-diphenylmethane, bis (4-hydroxyphenyl) methane, bis (4-hydroxy-5)
-Nitrophenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 3,3-bis (4-hydroxyphenyl) pentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, bis (4-hydroxy) Phenyl) sulfone, 2,4'-dihydroxydiphenylsulfone, 5-chloro-2,4'-dihydroxydiphenylsulfone, bis (4-hydroxyphenyl) diphenyldisulfone, bis (4-hydroxyphenyl) sulfide, 4,4'- Dihydroxydiphenyl ether, 4,
Examples include 4'-dihydroxy-3,3'-dichlorodiphenyl ether and 4,4'-dihydroxy-2,5-diethoxydiphenyl ether. Of these dihydroxyaryl compounds, due to their availability, 2,
Generally, 2-bis (4-hydroxyphenyl) propane is often used, but these can be used alone or in combination of two or more, and can be made into a copolymer if necessary.

A catalyst is generally used in the reaction of the present invention, but the catalyst used is not particularly limited, and is usually a catalyst used in the transesterification reaction of the present invention, such as an alkali metal compound, an alkaline earth compound or a boron-based compound. A compound, an amine compound, or a phosphorus compound can be used. These may be used alone or in combination of two or more. The amount of the catalyst used is usually 0.01 to 3 mol%, preferably 0.05 to 1 mol% based on the dihydroxyaryl compound.

Examples of the alkali metal compound include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, sodium acetate, potassium acetate, Lithium acetate, sodium stearate, potassium stearate, lithium stearate, sodium borohydride, lithium borohydride, sodium phenyl borohydride, sodium benzoate, potassium benzoate, lithium benzoate, disodium hydrogen phosphate, phosphoric acid 2 potassium hydrogen, 2 lithium hydrogen phosphate, 2 sodium phenyl phosphate, 2 potassium phenyl phosphate, 2 lithium phenyl phosphate, 2 sodium salt of bisphenol A, 2 potassium salt of bisphenol A, bispheno 2 the lithium salt of A, the sodium salt of phenol, potassium salt of phenol, lithium salt of phenol is exemplified.

Examples of the alkaline earth metal compound include calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium hydrogen carbonate, barium hydrogen carbonate, magnesium hydrogen carbonate, strontium hydrogen carbonate, calcium carbonate and carbonic acid. Examples thereof include magnesium, barium carbonate, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate, calcium stearate, barium stearate, magnesium stearate, and strontium stearate.

In addition, examples of the boron-based compound include tetramethylboron, tetraethylboron, tetrapropylboron, tetrabutylboron, trimethylethylboron, trimethylbenzylboron, trimethylphenylboron, triethylmethylboron, triethylbenzylboron, triethylphenyl. Boron, tributylmethylboron, tributylbenzylboron, tributylphenylboron, tetotiphenylboron, benzyltriphenylboron, methyltriphenylboron, butyltriphenylboron, etc., sodium salts, potassium salts, lithium salts, calcium salts, magnesium salts, Barium salt,
Alternatively, strontium salt and the like are exemplified.

Further, amine compounds such as 4-aminopyridine, 2-aminopyridine, N, N-dimethyl-4-aminopyridine, 4-diethylaminopyridine, 2-hydroxypyridine, 4-hydroxypyridine, 2-methoxypyridine,
4-methoxypyridine, 2-dimethylaminoimidazole, 2-methoxyimidazole, imidazole, 2-mercaptoimidazole, 2-methylimidazole, 4-methylimidazole, aminoquinoline and the like are exemplified.

Examples of phosphorus compounds include triethylphosphine, tri-n-propylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, tributylphosphite and triphenylphosphite.

Of these catalysts, it is practically preferable to use a compound of an alkali metal or an alkaline earth metal because it is inexpensive, and examples of the alkali metal compound include:
Sodium hydroxide, potassium hydroxide, lithium hydroxide,
Sodium hydrogen carbonate, potassium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, sodium acetate, potassium acetate, lithium acetate, sodium stearate,
Potassium stearate, sodium borohydride, as the alkaline earth metal compound, for example, calcium hydroxide, barium hydroxide, magnesium hydroxide, calcium hydrogen carbonate, barium hydrogen carbonate, magnesium hydrogen carbonate, calcium carbonate, magnesium carbonate, Barium carbonate, calcium stearate, barium stearate,
Examples include magnesium stearate.

The transesterification reaction is generally carried out in two or more stages. Specifically, the first step reaction
The reaction is carried out at a temperature of 20 to 260 ° C., preferably 180 to 240 ° C. for 0 to 5 hours, preferably 0.5 to 3 hours. Then, the reaction temperature is raised while increasing the degree of vacuum of the reaction system, and finally, the polycondensation reaction is carried out at a temperature of 240 to 320 ° C. under a reduced pressure of 1 mmHg or less.

The above reaction may be carried out by a batch system, a continuous system or a combination of a batch system and a continuous system, and an apparatus to be used may be a tank system, a tube system or a column system. .

[0028]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples. The polycarbonate obtained was evaluated by the following methods.

(1) Molecular Weight (Mv) Using an Ubbelohde viscometer, the intrinsic viscosity [η] at 20 ° C. in methylene chloride was measured and determined from the following formula. [Η] = 1.23 × 10 ⁻⁴ (Mv) ^0.83

(2) Amount of terminal OH Titanium tetrachloride / acetic acid method (Makromol Chem. 88 215 (1965))
Colorimetric determination was carried out by.

(3) Hue Using the obtained polycarbonate, 50 mmφ, 3.
An injection-molded product having a thickness of 0 mm was manufactured, and the YI value was measured using a colorimeter manufactured by Tokyo Denshoku. (The smaller the value, the better the hue)

Example 1 Electrolytic polishing treatment was performed on the surface of the wetted part of a reactor (reactor main body, stirring blade, stirring shaft) made of SUS-310S and having a capacity of 3 liters, and then saturated ethylenediamine at 80 ° C. It was immersed in an aqueous solution of tetraacetic acid for 5 hours.

The reactor which has been subjected to the above treatment is placed in a diphen
1,103 g (5.15 mol) of carbonate, 2,2
-Bis (4-hydroxyphenyl) propane [= bisph
Enol A] 1,142 g (5.00 mol) and hydroxy acid
Sodium iodide 7.50 x 10 ^-6Charge the moles, nitrogen atmosphere
After keeping at 180 ℃ under air for 1 hour, decompression degree is 100m
At the same time as mHg, at a speed of 25K / hr at 280 ° C
The temperature was raised to 280 ° C. and maintained for 2 hours. After the start of temperature rise 2
When the time has passed, the degree of pressure reduction in the reaction vessel is set to 50 mmHg
After the lapse of 1 hour, the degree of pressure reduction is set to 10 mmHg,
After 30 minutes, reduce the pressure to 1 mmHg or less, and stir.
The reaction was performed for a total of 7 hours. After the reaction is complete, from the bottom of the reactor
The resin was taken out and pelletized by a pelletizer. Profit
The obtained polycarbonate has Mv = 22,000, the terminal
OH = 0.0160% by weight, YI value = 1.18, which is excellent.
It was a hue.

Example 2 Instead of saturated aqueous solution of ethylenediaminetetraacetic acid, saturated L-
A reactor was treated and reacted in the same manner as in Example 1 except that an aspartic acid aqueous solution was used to produce a polycarbonate. The obtained polycarbonate has Mv = 2
2,200, terminal OH = 0.155% by weight, YI value =
The hue was 1.19, which was a good hue.

Example 3 3% by weight in place of the saturated ethylenediaminetetraacetic acid aqueous solution
A polycarbonate was produced by treating the reaction apparatus and carrying out the reaction in the same manner as in Example 1 except that an aqueous solution of salicylic acid was used. The obtained polycarbonate has Mv = 22.0
00, terminal OH = 0.0160% by weight, YI value = 1.1
The hue was 9, which is a good hue.

Comparative Example 1 SUS-310 in which only the electrolytic polishing treatment was applied to the surface of the liquid contact portion
Using a reactor made by S, the reaction was carried out in the same manner as in Example 1 to produce a polycarbonate. The obtained polycarbonate has Mv = 22,300 and terminal OH = 0.155.
% By weight and YI value = 1.30.

[0037]

As described above, after the electrolytic polishing treatment is applied to the surface of the wetted portion of the reactor made of stainless steel material,
By using a reaction apparatus in which a chelating agent solution is subjected to a dipping treatment, a polycarbonate having an excellent hue can be produced, which is an industrially extremely effective method.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Masayuki Nakajima 22 Wadai, Tsukuba, Ibaraki Prefecture Mitsubishi Gas Chemical Co., Ltd.

Claims (2)

[Claims] 1. When a polycarbonate is produced by reacting a carbonic acid diester with a dihydroxyaryl compound, an electrolytic polishing treatment is applied to the surface of the wetted portion of a reactor made of a stainless steel material, and then a dipping treatment is performed in a chelating agent solution. A method for producing a polycarbonate, which comprises using a reactor which has been subjected to the above. 2. The method for producing a polycarbonate according to claim 1, wherein the material of the reactor is stainless steel having a nickel content of 12% by weight or more and a chromium content of 22% by weight or more.