JP3502735B2 - Method for producing polycarbonate - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a so-called transesterification polycarbonate. More specifically, it relates to a method for producing a polycarbonate having excellent hue, heat resistance, and hydrolysis stability.

[0002]

2. Description of the Related Art The so-called transesterification method for producing a polycarbonate by polycondensing a carbonic acid diester and a dihydroxyaryl compound has a relatively simple process as compared with the phosgene method (interfacial polymerization method), and in terms of operation and cost It has recently been reviewed from the viewpoint of environmental protection in that it not only exhibits superiority but also does not use halogen-based solvents such as highly toxic phosgene and methylene chloride. However, in the method for manufacturing polycarbonate by the conventional transesterification method generally alkali metal compound as a catalyst component, a basic compound such as an alkaline earth metal compound based on the aromatic dihydroxy compound to 1 mol, 10 ^-2 to 10 ^- Used in an amount of ⁸ mol. However, the polycarbonate resin obtained by using such a catalyst lacks thermal stability due to the remaining catalyst, and a part of the resin may be thermally decomposed during melting and molding, resulting in a decrease in the molecular weight of the polycarbonate or transparency. Is deteriorated and there is a problem such as coloring. In order to solve this problem, various studies have hitherto been made, for example, a method of adding an acidic compound to neutralize the residual catalyst has been disclosed (Japanese Patent Publication No. 54-44303, JP-A-04-43).
328124, JP-A-07-062077, JP-A-07-126374, JP-A-08-059975,
JP-A-08-259687). However,
Even by these methods, the hue and thermal stability of the obtained polycarbonate were still unsatisfactory.

[0003]

The object of the present invention is to solve the problems of the quality of the polycarbonate obtained by the transesterification method, and to produce a polycarbonate having an improved hue and thermal stability. It provides a way to do it.

[0004]

Means for Solving the Problems As a result of intensive studies to solve these problems, the present inventors have found that in a molten polycarbonate resin obtained by a transesterification method,
The knowledge that dispersion of the acidic compound in the resin is good by adding the acidic compound in the state of an aqueous solution to neutralize the basic catalyst and kneading, and the concentration of the acidic compound solution is The present inventors have found that it is one of the major factors affecting stability and found that the above problem can be solved by adding an acidic compound as a solution with a specific concentration, and have completed the present invention. That is, the present invention, a polycarbonate obtained by polycondensation of a carbonic acid diester and a dihydroxyaryl compound in the presence of a basic transesterification catalyst, when continuously devolatilized using a vent type extruder, acidic Compound 7 × 1
It is intended to provide a method for producing a polycarbonate, which comprises adding as a solution dissolved in a solvent at a concentration of 0 ^-5 mol / g or less.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The polycarbonate according to the present invention is produced by a so-called transesterification method,
Carbonic acid diester, which is one of the raw material monomers, is represented by the following general formula (1).

[0006]

[Chemical 1]

(In the formula, A is a monovalent aliphatic group having 1 to 18 carbon atoms or a substituted aliphatic group, or a monovalent aromatic group or a substituted aromatic group, and A is the same or different. Examples of the carbonic acid diester represented by the general formula (1) include diphenyl carbonate, substituted diphenyl carbonate, dimethyl carbonate, diethyl carbonate,
Examples thereof include ditolyl carbonate and di-t-butyl carbonate. Particularly preferred are diphenyl carbonate and substituted diphenyl carbonate. These carbonic acid diesters may be used alone or in combination of two or more. Further, with the above-mentioned carbonic acid diester, preferably 50 mol% or less, more preferably 30 mol%
You may use dicarboxylic acid or dicarboxylic acid ester in the following amounts. As such a dicarboxylic acid or dicarboxylic acid ester, terephthalic acid, isophthalic acid, diphenyl terephthalate, diphenyl isophthalate or the like is used. When such a diester is used in combination, polyester carbonate is obtained. The dihydroxyaryl compound which is another raw material monomer is represented by the following general formula (2).

[0008]

[Chemical 2]

(Wherein B is 2 having a carbon number of 1 to 15)
Valent hydrocarbon groups, halogen-substituted divalent hydrocarbon groups, or -O-, -S-, -CO-, -SO- or -SO
₂ - In those selected from the group consisting of divalent groups represented, X and Y is a different material to the same or another, those selected from hydrogen or halogen or a hydrocarbon group having 1 to 6 carbon atoms And p and q are integers of 0-2. )

Some representative examples are, for example, bis (4-hydroxyphenyl) methane, 2,2-bis (4
-Hydroxyphenyl) propane, 2,2-bis (4-
Hydroxy-3-methylphenyl) propane, 2,2-
Bis (4-hydroxy-3-t-butylphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (4-hydroxy-)
Bisphenols such as 3,5-dibromo) propane, 4,4-bis (4-hydroxyphenyl) heptane, and 1,1-bis (4-hydroxyphenyl) cyclohexane;
Biphenols such as 4'-dihydroxybiphenyl, 3,3 ', 5,5'-tetramethyl-4,4'-dihydroxybiphenyl; bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfide, bis ( 4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) ketone and the like. Among these, 2,2-bis (4-hydroxyphenyl) propane (abbreviation: bisphenol A) is preferable. These dihydroxyaryl compounds can be used alone or in admixture of two or more, and can be made into a copolymer if necessary.

When a polycarbonate is produced by the transesterification method, a basic catalyst is usually used. In the production of the polycarbonate in the present invention, the catalyst species is not limited, but generally, an alkali metal compound, an alkaline earth metal compound, a basic boron compound, a basic phosphorus compound, a basic ammonium compound or an amine compound, etc. Basic compounds are used. These may be used alone or in combination of two or more. The catalyst is usually used in an amount of 1 × 10 ⁻⁹ to 1 × 10 ⁻³ mol, preferably 1 × 10 ⁻⁷ to 1 × 10 ⁻⁴ mol, based on 1 mol of the dihydroxyaryl compound.

As the alkali metal compound, lithium,
There are inorganic alkali metal compounds such as hydroxides, carbonates and hydrogen carbonate compounds of sodium, potassium, rubidium and cesium, and organic alkali metal compounds such as salts with alcohols, phenols and organic carboxylic acids. Among these alkali metal compounds, cesium compounds are preferable, and the most preferable cesium compounds are specifically cesium carbonate, cesium hydrogen carbonate, and cesium hydroxide.

As the alkaline earth metal compound,
Inorganic alkaline earth compounds such as beryllium, calcium, magnesium, strontium hydroxides, carbonates,
Examples include organic alkaline earth metal compounds such as salts with alcohols, phenols, and organic carboxylic acids.

Examples of the basic boron compound include tetramethylboron, tetraethylboron, tetrapropylboron, tetrabutylboron, trimethylethylboron, trimethylbenzylboron, trimethylphenylboron, triethylmethylboron, triethylbenzylboron, triethylphenylboron, Hydroxides of tributylbenzylboron, tributylphenylboron, tetraphenylboron, benzyltriphenylboron, methyltriphenylboron, butyltriphenylboron, etc.,
Examples thereof include sodium salt, potassium salt, lithium salt, calcium salt, magnesium salt, barium salt, and strontium salt.

Examples of the basic phosphorus compound include triethylphosphine, tri-n-propylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, tributylphosphine,
Alternatively, quaternary phosphonium salts and the like are exemplified.

Examples of the basic ammonium compound include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethylethylammonium hydroxide, trimethylbenzylammonium hydroxide, trimethylphenylammonium. Hydroxide, Triethylmethylammonium Hydroxide, Triethylbenzylammonium Hydroxide, Triethylphenylammonium Hydroxide, Tributylbenzylammonium Hydroxide, Tributylphenylammonium Hydroxide, Tetraphenylammonium Hydroxide, Benzyltriphenylammonium Hydroxide , Methyltriphenylphosphonium ammonium hydroxide, butyltriphenyl ammonium hydroxide and the like.

Examples of amine compounds include 4-aminopyridine, 2-aminopyridine, N, N-dimethyl-4-aminopyridine, 4-diethylaminopyridine,
2-hydroxypyridine, 2-methoxypyridine, 4-
Methoxypyridine, 2-dimethoraminoimidazole,
2-methoxyimidazole, imidazole, 2-mercaptoimidazole, 2-methylimidazole, aminoquinoline and the like are exemplified.

Of these catalysts, alkali metal compounds are practically desirable. The transesterification reaction is generally carried out in a multi-step process of two or more steps. Specifically, the first
The reaction in the second stage is 120 to 260 ° C. under normal pressure or reduced pressure,
Preferably at a temperature of 180-240 ° C for 0.1-5 hours,
The reaction is preferably carried out for 0.5 to 3 hours. Next, raise the reaction temperature while raising the pressure reduction degree of the reaction system, and finally 1 mm.
The polycondensation reaction is performed at a temperature of 240 to 320 ° C. under a reduced pressure of Hg or less. The reaction form may be a batch system, a continuous system, or a combination of a batch system and a continuous system,
The apparatus used may be of any of a tank type, a tube type and a tower type.

The polycarbonate resin used in the present invention has a viscosity average molecular weight (Mv) of 10,000 to 100,0.
00 is preferable, and 12,000 to 40,000 is particularly preferable.

In the present invention, the acidic compound to be added is not particularly limited, and any compound having an effect of neutralizing the basic transesterification catalyst used in the polycondensation reaction can be used. Specifically, hydrochloric acid, nitric acid, boric acid, sulfuric acid, sulfurous acid, phosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid, adipic acid, ascorbic acid, aspartic acid, azelaic acid, adenosine phosphoric acid, benzoic acid, Formic acid, valeric acid, citric acid, glycolic acid, glutamic acid, glutaric acid, cinnamic acid, succinic acid, acetic acid, tartaric acid, oxalic acid, p-toluenesulfinic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, nicotinic acid, picrin Acid, picolinic acid,
Examples thereof include Bronsted acids such as phthalic acid, terephthalic acid, propionic acid, benzenesulfinic acid, benzenesulfonic acid, malonic acid and maleic acid, and esters thereof. These may be used alone or in combination of two or more. Among these acidic compounds, a sulfonic acid compound or an esterified product thereof, such as methyl benzenesulfonate, is particularly preferable.

As the solvent for dissolving the acidic compound, it is sufficient that the acidic compound is dissolved, and water is particularly preferable. For an acidic compound insoluble in water alone, a mixed solvent obtained by adding an organic solvent such as acetone to water (the mixing ratio of water and acetone is 0.1 to 1.5 parts by weight of acetone with respect to 1 part by weight of water). ) Is preferred. Further, when an organic solvent is used, acetones, aliphatic or aromatic hydrocarbon compounds that do not adversely affect the polycarbonate are particularly preferably used.

In the present invention, the amount of these acidic compounds is 7
It is characterized in that it is added as a solution dissolved in a solvent at a concentration of × 10 ^-5 mol / g or less. Further, it is preferable to be 7 × 10 ⁻⁵ mol / g or less and 7 × 10 ⁻⁸ mol / g or more due to the temperature decrease in the extruder due to the introduction of the acidic compound solution and the limitation on the apparatus. Furthermore, practically, 7 × 10 ⁻⁵ mol
/ G or less and 3 × 10 ^-6 mol / g or more is preferable.

The amount of solvent used is 100% polycarbonate.
With respect to parts by weight, 0.05 to 4 parts by weight, preferably 0.1 to
Use 2 parts by weight. When to add an acidic compound,
It may be added at any time before the devolatilization operation, and the addition method is not particularly limited. As an efficient method, before the vent part of the extruder, that is, the acidic compound is continuously added to an extruder having an inlet for the acidic compound and a kneading part with the resin on the resin supply side, and the catalyst in the resin is added. A method of neutralizing and deactivating is mentioned.

The extruder used in the present invention may be of any type provided that it has a vent portion. Specific examples thereof include vent-type single-screw or multi-screw extruders, but interlocking twin-screw extruders are particularly preferable, and the rotation directions may be the same direction rotation or different direction rotations. The number of vents is not limited, but a multistage vent having 2 to 10 stages is usually used. In the case of an extruder equipped with multiple vents, the acidic compound is added before the vent closest to the resin feed port. If necessary, water may be added from another vent port other than the vent port for adding the acidic compound solution.

As the form of the resin to be subjected to the neutralization devolatilization treatment by the extruder, the resin is introduced into the extruder while it is in a molten state immediately after the polymerization, and the resin is once cooled and solidified and then introduced into the extruder. Any of the following methods may be used. Further, the extruder can be kneaded with a resin by adding additives such as a stabilizer, an ultraviolet absorber, a release agent and a colorant, if necessary.

[0026]

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 analysis was performed by the following method. (1) Molecular weight Using an Ubbelohde viscometer, the intrinsic viscosity [η] at 20 ° C. in methylene chloride was measured and determined from the following formula. [Η] = 1.11 × 10 ⁻⁴ × (Mv) ^0.83 (2) Evaluation of thermal stability After drying 4 g of polycarbonate resin at 120 ° C. for 2 hours in a nitrogen atmosphere, 360 ° in an aluminum block bath under a nitrogen atmosphere. Melt at ℃ for 1 hour. After cooling, dissolve in 25 ml of methylene chloride and use the automatic color analyzer "TC-1800MKII" (trade name) manufactured by Tokyo Denshoku Co., Ltd., cell length 5
The YI value was measured by 5 mm (the smaller the value, the better the hue).

Examples 1 to 6 and Comparative Examples 1 to 2 Bisphenol A (BPA) and diphenyl carbonate (DPC) were mixed at a constant molar ratio (DP) in a nitrogen gas atmosphere.
C / BPA = 1.040) and the melt mixture was mixed and prepared at a flow rate of 401.064 mol / hour, and was controlled at 210 ° C. under normal pressure and nitrogen atmosphere through the raw material introducing pipe.
The liquid was continuously fed into the vertical stirring polymerization tank, and the liquid level was kept constant while controlling the valve opening provided in the polymer discharge line at the bottom of the tank so that the average residence time was 60 minutes. At the same time when the supply of the raw material mixture was started, 350 ml of 0.02 wt% cesium carbonate aqueous solution was used as a catalyst.
/ Hour (1 × 10 ⁻⁶ mol per 1 mol of bisphenol A) was continuously supplied. The polymerization liquid discharged from the bottom of the tank continues to flow in the second, third, and fourth vertical polymerization tanks and the fifth polymerization tank.
Was continuously and continuously supplied to the horizontal polymerization tank. During the reaction, the liquid level was controlled so that the average residence time in each tank was 60 minutes, and at the same time, the by-produced phenol was distilled off.

The polymerization conditions of each reaction tank between the second to fifth polymerization tanks are as follows: the second polymerization tank (210 ° C., 100 Tor).
r, 200 rpm), 3rd polymerization tank (240 ° C, 15To)
rr, 100 rpm), 4th polymerization tank (270 ° C, 0.5)
Torr, 44 rpm), 5th polymerization tank (280 ° C., 0.1)
5 Torr, 10 rpm) and high temperature as the reaction progresses,
Conditions were set to high vacuum and low stirring speed. The molecular weight of the polycarbonate thus obtained was Mv = 23,000.

A twin-screw extruder (manufactured by Kobe Steel Co., Ltd.) equipped with four vents in the molten state of this polymer and having an acidic compound injection hole in front of the vent closest to the resin supply port. , Screw diameter 46 mm, meshing screw type, rotating in the same direction), the acidic compound was continuously added under the conditions shown in Table 1, devolatilized and pelletized. The acidic compound is a water-acetone mixed solvent (1: 1).
Was added as. The results of thermal stability of the obtained polycarbonate resin are shown in Table 1.

Comparative Example 3 A catalyst was deactivated in the same manner as in Example 2 except that the acidic compound was directly added to the twin-screw extruder without being dissolved in the mixed solvent to obtain a polycarbonate.

[0031]

[Table 1]

Example 7 Bisphenol A (BPA) and diphenyl carbonate (DPC) were mixed at a constant molar ratio (DP) under a nitrogen gas atmosphere.
C / BPA = 1.040) and the melt mixture was mixed and prepared at a flow rate of 401.064 mol / hour, and was controlled at 210 ° C. under normal pressure and nitrogen atmosphere through the raw material introducing pipe.
The liquid was continuously fed into the vertical stirring polymerization tank, and the liquid level was kept constant while controlling the valve opening provided in the polymer discharge line at the bottom of the tank so that the average residence time was 60 minutes. At the same time when the supply of the raw material mixture was started, 350 ml of 0.02 wt% cesium carbonate aqueous solution was used as a catalyst.
/ Hour (1 × 10 ⁻⁶ mol per 1 mol of bisphenol A) was continuously supplied. The polymerization liquid discharged from the bottom of the tank was successively continuously supplied to the second, third, and fourth vertical polymerization tanks and the fifth horizontal polymerization tank. During the reaction, the liquid level was controlled so that the average residence time in each tank was 60 minutes, and at the same time, the by-produced phenol was distilled off.

The polymerization conditions of each reaction tank between the second to fifth polymerization tanks are as follows: the second polymerization tank (210 ° C., 100 Tor).
r, 200 rpm), 3rd polymerization tank (240 ° C, 15To)
rr, 100 rpm), 4th polymerization tank (270 ° C, 0.5)
Torr, 44 rpm), 5th polymerization tank (280 ° C., 0.1)
5 Torr, 10 rpm) and high temperature as the reaction progresses,
Conditions were set to high vacuum and low stirring speed. The molecular weight of the polycarbonate thus obtained was Mv = 23,000.

This polymer was introduced in a molten state into a twin-screw extruder equipped with four vents and having an acidic compound injection hole in front of the vent closest to the resin supply port, and 6.
Neutralization was performed in the same manner as in Example 1 except that 31 × 10 ⁻⁵ mol / g aqueous p-toluenesulfonic acid solution was continuously added at a flow rate of 82.0 g / hour. When the thermal stability of the obtained pellet was measured, it was YI = 1.5.

[0035]

As can be seen from the results of Table 1 and Example 7, when an acidic compound having a concentration specified in the present invention is used for neutralizing the catalyst, the thermal stability of the produced polycarbonate is extremely excellent. .

Front page continuation (72) Inventor Katsushige Hayashi 2-4-16 Hinagahigashi, Yokkaichi-shi, Mie Mitsubishi Gas Chemical Co., Ltd. Yokkaichi factory (72) Inventor Tsutomu Kawakami 2-4th Hinagahigashi, Yokkaichi-shi, Mie No. 16 Mitsubishi Gas Chemical Co., Ltd. Yokkaichi Plant (56) Reference JP-A-8-259688 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 64/00-64/42

Claims (5)

(57) [Claims] 1. A polycarbonate obtained by polycondensing a carbonic acid diester and a dihydroxyaryl compound in the presence of a basic transesterification catalyst is acidified when continuously devolatilized using a vent type extruder. A method for producing a polycarbonate, wherein the compound is added as a solution dissolved in a solvent at a concentration of 7 × 10 ⁻⁸ mol / g to 7 × 10 ⁻⁵ mol / g. 2. The method for producing a polycarbonate according to claim 1, wherein the amount of the acidic compound added is 1 to 30 times the amount of the catalyst used. 3. With respect to 100 parts by weight of polycarbonate,
The method for producing a polycarbonate according to claim 1, wherein the solvent is used in an amount of 0.05 to 4 parts by weight. 4. The method for producing a polycarbonate according to claim 1, wherein the acidic compound is at least one selected from a sulfonic acid compound and an esterified product thereof. 5. The method for producing a polycarbonate according to claim 4, wherein the solvent that dissolves the acidic compound is selected from water and acetone.