JPH08259687A - Production of polycarbonate - Google Patents

Abstract

PURPOSE: To efficiently obtain a polycarbonate excellent in hue and heat and hydrolytic resistances by adding an acidic compound to a part before a prescribed vent port in a vented type extruder, kneading the resultant mixture, then introducing water thereinto and continuously removing volatile matter from the polycarbonate. CONSTITUTION: To (A) a polycarbonate obtained by carrying out the polycondensation of a carbonic diester with a dihydroxyaryl compound in the presence of a transesterification catalyst [e.g. an alkali(alkaline earth) metal compound, a basic boron compound, a basic phosphorus compound, a basic ammonium compound or an amine compound], (B) an acidic compound [e.g. an inorganic acid, a carboxylic acid (ester), sulfonic acid (ester) or sulfinic acid (ester)] is added in the part before a vent port nearest to a resin feed port in a vented type extruder, they are kneaded and to the resultant mixture water is introduced and volatile matter is continuously removed. Thereby, the objective polycarbonate is obtained. The amount of introduced water is 0.1-10wt.% based on the amount of the extruded resin based on one stage.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a so-called transesterification polycarbonate. Specifically, it relates to a method for producing a polycarbonate having excellent hue, heat stability, 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 is relatively simple in process and superior in operation and cost as compared with the phosgene method (interfacial polymerization method). It has recently been reviewed from the viewpoint of environmental protection in that it not only exerts its properties but also does not use halogen-based solvents such as highly toxic phosgene and methylene chloride. However, at present, the adoption of the transesterification method as an industrial process is still small.

The reason for this is that the polycarbonate produced by the conventional transesterification method has some drawbacks in terms of quality, and in particular, the hue, heat stability, and hydrolysis stability are poor. It's a big problem.

In order to solve this problem, various studies have been made so far. For example, improvement of catalyst
-1420225, JP-A-2-124934, JP-A-2-212518), examination of reactor material and surface treatment (US Pat. No. 4,383,092, JP-A-4-7328)
JP-A-4-72327), examination of polymerization process and polymerization apparatus (JP-A-61-62522, JP-A2-1).
No. 53923), examination of terminal sealing (Japanese Patent Laid-Open No. 63-439).
24, JP-A-2-175723), investigation of stabilizers (JP-A-4-15223, JP-A-4-36344,
JP-A-4-41525) and the like.

However, it is still difficult to obtain a polycarbonate having excellent hue, heat stability and hydrolysis stability even if the above method is adopted.

[0006]

The object of the present invention is to solve the problems of the quality of the polycarbonate obtained by the transesterification method, and to improve the hue, heat stability and hydrolysis stability. Provided is a method of making an improved polycarbonate.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve these problems, and as a result, have found that the raw material monomer remaining as a by-product hydroxy in the polycarbonate resin obtained by the transesterification method. It was found that the presence of low molecular weight compounds such as compounds, catalysts and oligomers is a major cause of deterioration of hue, thermal stability and hydrolysis stability,
The inventors have found a method for efficiently removing these low molecular weight components and completed the present invention.

That is, according to the present invention, when a polycarbonate obtained by a polycondensation reaction of a carbonic acid diester and a dihydroxyaryl compound in the presence of a transesterification catalyst is continuously devolatilized by using a vent type extruder, The present invention relates to a method for producing a polycarbonate, characterized in that an acidic compound is added to a resin supply port of an extruder in front of a recent vent portion, kneaded, and then water is introduced to continuously volatilize the compound.

The polycarbonate according to the present invention is produced by a so-called transesterification method, and carbonic acid diester which is one of the raw material monomers is represented by the following general formula (1).

[0010]

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(In the formula, A is a monovalent aliphatic or substituted aliphatic group having 1 to 18 carbon atoms, or a monovalent aromatic group or a substituted aromatic group, and A is the same or different. Good too.)

Examples of the carbonic acid diester represented by the above general formula (1) include diphenyl carbonate, substituted diphenyl carbonate, dimethyl carbonate, diethyl carbonate, ditolyl carbonate, di-t-butyl carbonate, and the like. Preferred are diphenyl carbonate and substituted diphenyl carbonate. These carbonic acid diesters may be used alone or in combination of two or more.

The amount of the above-mentioned carbonic acid diester is preferably 50 mol% or less, more preferably 30%.
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 which is another raw material monomer is represented by the following general formula (2).

[0015]

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(Wherein A is 2 having a carbon number of 1 to 15)
Valent hydrocarbon group, a divalent halogenated bid hydrogen radical or _{-S -, - S 2 -,} - SO 2 -, - SO -, - O-, and shows a -CO- divalent group 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 0-4. )

The dihydroxyaryl compound represented by the above general formula (2) is, for example, 2,2-bis (4-hydroxyphenyl) propane [= bisphenol A], 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-hydroxyphenyl) sulfone, 2,4′-dihydroxydiphenylsulfone, bis (4-hydroxyphenyl) diphenyldisulfone, Bis (4-hydroxyphenyl) sulfide, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3,3'-dichlorodiphenyl ether, 4,4'-dihydroxy-
2,5-diethoxydiphenyl ether and the like are exemplified. These dihydroxyaryl compounds may be used alone or in admixture of two or more, and may be used as a copolymer if necessary.

When a polycarbonate is produced by the transesterification method, a catalyst is usually used. In producing the polycarbonate in the present invention, there is no limitation on the catalyst species, but generally, an alkali metal compound, an alkaline earth metal compound, a basic boron compound, a basic phosphorus compound,
A basic compound such as a basic ammonium compound or an amine compound is used. These may be used alone or in combination of two or more. The amount of the catalyst used is usually 1 × 10 ⁻⁹ to 1 × 10 ⁻³ mol, preferably 1 ×, relative to 1 mol of the dihydroxyaryl compound.
It is used in the range of 10 ⁻⁷ to 1 × 10 ⁻⁵ mol.

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, and the like.

As the alkaline earth metal compound,
For example, calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium hydrogen carbonate, barium hydrogen carbonate, magnesium hydrogen carbonate, strontium hydrogen carbonate, calcium carbonate, magnesium carbonate, barium carbonate, strontium carbonate, calcium acetate, acetic acid. Examples include barium, magnesium acetate, strontium acetate, calcium stearate, magnesium stearate, barium stearate, and strontium stearate.

Examples of the basic boron compound include tetramethylboron, tetraethylboron, tetrapropylboron, tetrabutylboron, trimethylethylboron, trimethylbenzylboron, trimethylphenylboron, triethylmethylboron, triethylbenzylboron and 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, trimethylphenyl. Ammonium 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-dimethylaminoimidazole,
2-methoxyimidazole, imidazole, 2-mercaptoimidazole, 2-methylimidazole, aminoquinoline and the like are exemplified.

Of these catalysts, it is practically preferable to use an alkali metal or alkaline earth metal compound because it is inexpensive.

The transesterification reaction is generally carried out in a multi-step process of two or more steps. Specifically, the reaction in the first step is carried out under atmospheric pressure or reduced pressure at 120 to 260 ° C., preferably 1
The reaction is performed at a temperature of 80 to 240 ° C. for 0.1 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 reaction may be carried out in a batch system, a continuous system or a combination of a batch system and a continuous system, and the apparatus used may be a tank system, a tube system or a column system. Good.

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

In the polycarbonate produced by the above method, low molecular weight compounds such as raw material monomers, catalysts, hydroxy compounds by-produced by transesterification reaction, and polycarbonate oligomers remain. Above all, the raw material monomer and the by-product hydroxy compound have a large residual amount, which adversely affects the physical properties of the polycarbonate resin.

In the present invention, as a method for removing the low molecular weight compounds remaining in these resins, a method of continuously devolatilizing with a vent type extruder is adopted. At that time, a base remaining in the resin is used. By neutralizing the acidic transesterification catalyst with an acidic compound in advance and inactivating it, side reactions during devolatilization can be suppressed and raw material monomers and low molecular weight compounds such as hydroxy compounds can be efficiently removed.

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, phthalic acid, terephthalic acid, propionic acid, benzenesulfinic acid, benzenesulfonic acid, malonic acid, maleic acid,
And Bronsted acids and esters thereof.

These acidic compounds may be added singly or in a combination of two or more, and the addition amount is 0.1 to the neutralization amount of the basic transesterification catalyst used in the polycondensation reaction.
It is added in a 50-fold molar amount, preferably in a range of 0.5 to 30-fold molar amount.

The acidic compound may be added at any time before the operation for introducing and devolatilizing water, and the addition method is not particularly limited. As an efficient method, in front of the vent part of the extruder, that is, using an extruder equipped with an introduction port for the acidic compound and a kneading part with the resin on the resin supply port side, the acidic compound is continuously added to The method of neutralizing and deactivating the catalyst of 1 is mentioned.

The addition form of the acidic compound is not limited, and depending on the properties of the acidic compound to be used and the desired conditions, a method of adding directly, a method of adding after dissolving in an appropriate solvent, or a master batch pellet is used. And the like.

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 multi-stage vent having 2 to 10 stages is usually used. In the case of an extruder equipped with a multi-stage vent port, the acidic compound is the most recent vent part (first vent port) in the resin supply port.
Is added from before.

To introduce water, it is necessary to add an acidic compound, knead it, and then introduce it before the vent port to mix and disperse water in the resin well and continuously devolatilize it from the vent port. Since the distance between the water inlet and the vent on the side of the outlet closest to the water inlet varies depending on the shape of the screw, the rotation speed, etc., it is actually desirable to determine in advance by experiments. In addition, it is more effective and preferable to introduce water in two or more stages depending on the number of vents.

The amount of water introduced is 0.1 to 10 wt%, preferably 0.3 to 5 wt%, continuously with respect to the amount of the extruded resin, regardless of the number of introduced stages. If the amount introduced is too small, a sufficient devolatilization effect cannot be obtained, and if the amount is too large, it causes hydrolysis of the resin, which is not preferable. The water used is not particularly limited, but water containing little dissolved oxygen is preferred.

The temperature of the resin during the devolatilizing extrusion treatment is 25
0 to 350 ° C., preferably 270 to 330 ° C., the pressure is 200 mmHg or less, preferably 50 mmHg
Do the following: The rotation speed of the extruder screw is 50
~ 500 rpm, preferably 100-300 rpm.

As a timing of devolatilizing the low molecular weight compound from the resin by the method of the present invention, it is generally appropriate to carry out after the completion of the polymerization reaction. As the form of the resin to be subjected to the devolatilization treatment by the extruder, a method of introducing into the extruder while it is in a molten state immediately after polymerization and a treatment, and a method of introducing into the extruder after cooling and solidifying, Either is fine.
It is also possible to add additives such as a stabilizer, an ultraviolet absorber, a release agent, and a coloring agent using the extruder, if necessary, and knead with the resin.

[0040]

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 quantitative analysis of the low molecular weight compounds (diphenyl carbonate, bisphenol A, phenol) remaining in the resin and the evaluation of the physical properties of the polycarbonate resin are as follows.
The following method was used.

(1) Quantification of residual low molecular weight compound A weighed polycarbonate sample is dissolved in methylene chloride, and acetone is gradually added while stirring to reprecipitate the resin. After thoroughly stirring, the precipitate is filtered off. After the filtrate is evaporated to dryness by an evaporator, the dried solid is redissolved in chloroform, and tert-butylphenol is quantified by GPC as an internal standard.

(2) Evaluation of Thermal Stability 4 g of a polycarbonate sample was dried in a nitrogen atmosphere at 120 ° C. for 2 hours and then melted in an aluminum block bath at 360 ° C. for 1 hour in a nitrogen atmosphere. After cooling, the product was dissolved in 25 ml of methylene chloride and was dissolved in an automatic color analyzer (Tokyo Denshoku Co., Ltd., MODEL; TC-1800MK).
Measure YI value according to II). (The smaller the value, the better the hue)

(3) Evaluation of Hydrolysis Stability An injection-molded product having a thickness of 3 mm was produced and left in a pressure cooker (manufactured by Alp Co., Ltd.) under the conditions of 120 ° C. steam and 100 hours. Haze meter (Model: 1001DP, Nippon Denshoku Co., Ltd.)
Measured by. (The smaller the value, the better the transparency)

(4) 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

Examples 1 to 8 and Comparative Examples 1 to 3 Diphenyl carbonate 11.03 kg (51.5 mol), Bisphenol A 11.42 kg (50.0 mol) and disodium phenylphosphate 8.0 × 10 ^-5
Mole to a reaction vessel equipped with a stirrer (SUS310S,
After charging to an effective volume of 50 L) and dissolving the raw material monomers at 180 ° C. for 40 minutes in a nitrogen atmosphere, 210 ° C./7
1 hour at 210 mm / 100 mmHg at 60 mmHg
Hour, 240 ° C / 15mmHg for 1 hour, 280 ° C /
The reaction was carried out under the conditions of 0.5 mmHg and 1 hour of polymerization. After completion of the reaction, the polymer was taken out from the reactor and pelletized by a pelletizer.

The batch reaction was repeated 20 times under the same conditions to produce a total of about 200 kg of polycarbonate resin. The viscosity average molecular weight (Mv) of the obtained polymer was minimum 16200 and maximum 16800. After well blending 20 batches of polymer, the Mv was 16600. Diphenyl carbonate remaining in the polycarbonate is 462 ppm and bisphenol A is 1
It was 18 ppm and phenol was 162 ppm.

Next, the obtained polycarbonate is equipped with a multi-stage vent port, the resin supply port is provided with an acidic compound inlet port before the latest vent port (first vent port), and a kneading section is provided. Twin-screw extruder equipped with (Kobe Steel Co., Ltd.)
Made, 46 mmφ, meshing screw type, rotating in the same direction)
Was subjected to a devolatilizing extrusion treatment under the conditions shown in Table-1, and was collected again as pellets. A master batch pellet was used for the addition of the acidic compound, and the acidic compound was continuously introduced by a quantitative side feeder. Table 1 shows the concentration of the low molecular weight compound remaining in the resin after the devolatilization extrusion treatment and the evaluation results of various physical properties.

[0049]

[Table 1]

[0050]

According to the present invention, a low molecular weight compound remaining in a polycarbonate resin can be efficiently removed, and as a result, a polycarbonate resin excellent in hue, thermal stability and hydrolysis stability can be obtained.

Front page continuation (72) Inventor Katsuhiro Iura 22 Wadai, Tsukuba, Ibaraki Mitsubishi Gas Chemical Co., Ltd.

Claims (7)

[Claims] 1. When a polycarbonate obtained by polycondensation of a carbonic acid diester and a dihydroxyaryl compound in the presence of a transesterification catalyst is continuously devolatilized by using a vent type extruder, a resin is supplied to the extruder. A method for producing a polycarbonate, characterized in that an acidic compound is added to the mouth before the recent vent mouth, kneaded, and then water is introduced to continuously volatilize. 2. The method for producing a polycarbonate according to claim 1, wherein the transesterification catalyst is a basic compound. 3. The transesterification catalyst is at least one selected from alkali metal compounds, alkaline earth metal compounds, basic boron compounds, basic phosphorus compounds, basic ammonium compounds, and amine compounds.
The method for producing a polycarbonate according to 1. 4. The method for producing a polycarbonate according to claim 1, wherein the acidic compound is at least one selected from an inorganic acid, a carboxylic acid, a sulfonic acid, a sulfinic acid, a carboxylic acid ester, a sulfonic acid ester and a sulfinic acid ester. 5. The method for producing a polycarbonate according to claim 1, wherein the vent type extruder is a twin-screw mesh type extruder having a multi-stage vent port. 6. The method for producing a polycarbonate according to claim 1, wherein water is introduced in at least two stages. 7. The method for producing a polycarbonate according to claim 1, wherein the amount of water introduced is 0.1 to 10 wt% with respect to the amount of the extruded resin per stage.