JP3117477B2 - Production method of polycarbonate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polycarbonate, and more particularly to a method for producing a polycarbonate by melt polycondensation of a divalent hydroxy compound and a bisaryl carbonate by a transesterification method. .

[0002]

BACKGROUND OF THE INVENTION Polycarbonate is a general engineering thermoplastic that has a wide range of uses, especially for injection molding or as a glass sheet replacement for window glass.

Hitherto, interfacial polycondensation, transesterification and the like have been applied to the production of these polycarbonates.
The interfacial polycondensation method is generally effective for the production of polycarbonate, but has disadvantages such as the use of toxic phosgene and the generation of chloride ions in the polycarbonate.

In order to solve these drawbacks, a method for producing a polycarbonate by interfacial polycondensation reaction with a special dihydric phenol using liquid trichloromethyl chloroformate which is a phosgene dimer instead of toxic phosgene. Is disclosed in JP-A-63-182336.

However, there is only description of 9,9-bis (4-hydroxyphenyl) fluorenes as a special dihydric phenol. In addition, triphosgene is used in place of toxic phosgene to give 2,2-bis (4
A method for obtaining polycarbonate from (-hydroxyphenyl) propane is described in Angew. Chem. (Angevante,
Hemy) 99.922 (1987), German Patent DE3
Although described in the specification of 440141, a reaction mechanism for generating phosgene has also been proposed.

[0006] In the transesterification reaction, a transesterification catalyst is added to diphenyl carbonate and an aromatic dihydroxy compound, and a prepolymer is synthesized while distilling off phenol under heating and reduced pressure.
A high molecular weight polycarbonate is obtained by heating above ℃ to distill phenol (US Pat. No. 4,345,062). However, unlike other engineering plastics, the high molecular weight polycarbonate has an extremely high melt viscosity. Since high temperature of 290 ° C. or higher is required as a reaction condition, and high vacuum (10 ⁻² Torr) is required to remove phenol having a high boiling point, industrialization is difficult from the viewpoint of equipment, and further production It is known that the residual phenol in the resulting polycarbonate has an undesirable effect on hue and physical properties.

However, various studies have been made on the transesterification method since it is possible to carry out the reaction by melt polycondensation and it is an industrially economical method. In particular, since the viscosity of the reaction system increases as the polycondensation reaction approaches completion, various types of apparatuses have been used to handle high-viscosity reaction products.

For example, JP-B-52-36159, JP-A-2-86618, and JP-A-2-153923 to 15392.
7 and the like are disclosed. Japanese Patent Publication No. 52-36159 uses a screw evaporator type interlocking twin-screw extruder (residence time is considered to be less than 15 minutes in this case). It has drawbacks in that it is easily generated, and it is difficult to control the residence time, and there is a problem in that the degree of coloring of the product due to heat history and the distillate such as phenol by-produced are efficiently removed.

Further, Japanese Patent Application Laid-Open No. 2-153923-1539
In No. 27, a horizontal stirring polymerization tank was used, but the hold-up was large, but the liquid thickness was large and the rate of distillation of phenol and the like by-produced from the high-viscosity reaction solution was rate-determining. (Usually a residence time of 60 minutes or more). Therefore, by receiving a heat history at a high temperature, it becomes a factor of coloring the reaction product. It is hard to say that it is a sufficient method for industrially efficiently producing a colorless and transparent high molecular weight polycarbonate.

[0010]

SUMMARY OF THE INVENTION The present invention overcomes the drawbacks of the conventional method for producing a polycarbonate by transesterification and provides a method for efficiently producing a colorless, transparent, high-molecular-weight polycarbonate. It is.

That is, the present inventors have proposed a method for producing a polycarbonate by melt-polycondensing a divalent hydroxy compound and a bisaryl carbonate by a transesterification method, wherein the viscosity average molecular weight is 5,000 to 20,000.
In the polycarbonate postcondensation step, the reaction temperature 1
By conducting a polycondensation reaction in a twin-screw extruder at 80 to 350 ° C., a reaction pressure of 10 Torr or less, and a residence time of 15 to 55 minutes , a colorless and transparent high molecular weight polycarbonate is industrially efficiently used. Finding that it can be manufactured well,
The present invention has been completed. More preferably, twin screw extrusion corresponding to the thickness of the reaction solution in the reaction section of the post-condensation step
The clearance between the two stirring means of the machine is 0.1mm ~ 50
It was found that by performing the polycondensation reaction in the range of mm, a high molecular weight polycarbonate can be obtained more efficiently.

The divalent hydroxy compound used in the present invention includes, for example, compounds represented by Chemical Formulas 1 to 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-triphenylethane, 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-butyl) Phenyl) propane,
1,1′-bis- (4-hydroxyphenyl) -p-diisopropylbenzene, 1,1′-bis- (4-hydroxyphenyl) -m-diisopropylbenzene, 1,1
-Bis- (4-hydroxyphenyl) cyclohexane and the like. Furthermore, it is also possible to produce a copolymerized polycarbonate by combining these two or three or more divalent hydroxy compounds.

As the bisaryl carbonate, diphenyl carbonate, bis (2,4-dichlorophenyl) carbonate, bis (2,4,6-trichlorophenyl) carbonate, bis (2-cyanophenyl) carbonate, bis (o- Nitrophenyl) carbonate,
Examples include ditolyl carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate, and the like. Preferably, it is diphenyl carbonate. In the present invention, a polymerization catalyst can be used if desired, and a transesterification catalyst is usually used as the polymerization catalyst.

Representative examples of the transesterification catalyst which can be used in the present invention include (a) lithium borohydride, sodium borohydride, potassium borohydride, rubidium borohydride as catalysts similar to metal-containing catalysts. ,
Cesium borohydride, 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 oxide (tetravalent), dibutyltin oxide, beryllium hydroxide, magnesium hydroxide, hydroxide Germanium, beryllium acetate, magnesium acetate, tin acetate (tetravalent), germanium acetate, lithium carbonate, sodium carbonate, potassium carbonate, beryllium carbonate, magnesium carbonate Um, tin carbonate (tetravalent), carbonate germanium, tin nitrate (tetravalent), germanium nitrate, antimony trioxide, bismuth trimethyl carboxylate.

(B) As a catalyst similar to the electron donating amine compound, 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, imidazole, 2-methylimidazole,
4-methylimidazole, diazabicyclooctane (D
ABCO) and the like.

(C) Carbonic acid, acetic acid, formic acid, nitric acid, nitrous acid, oxalic acid, borofluoric acid, hydrofluoric acid, etc. of the above-mentioned electron donating amine compound. (D) Examples of the catalyst similar to the electron-donating phosphorus compound include triethylphosphine, tri-n-propylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, tri-o-dimethoxyphenylphosphine, and tri-p. -Tolyl phosphine, tri-o-tolyl phosphine, tributyl phosphite, triphenyl phosphite, tri-p-tolyl phosphite, tri-o-tolyl phosphite and the like.

Further, (e) a catalyst similar to the borane complex includes a complex of borane and the following compound, namely, ammonia, dimethylamine, trimethylamine, triethylamine, t-butylamine, dimethylaniline, pyridine, dimethylaminopyridine, morpholine, Complexes such as piperazine, pyrrole, tetrahydrofuran, dimethylsulfide, tri-n-butylphosphine, triphenylphosphine, and triphenylphosphite are exemplified.

These catalysts may be used alone or in combination of two or more. The amount of the catalyst used is usually in the range of 1 × 10 ⁻⁶ to 1 mol based on the divalent hydroxy compound. But preferably 5 × 10
^{−5 to} 5 × 10 ⁻² mol. If the amount is less than 5 × 10 ⁻⁵ mol, the polymerization rate becomes slow and causes coloring. 5 × 10
^{If the amount} exceeds ^-2 mol, the catalyst remaining in the obtained polycarbonate adversely affects the physical properties, for example, a factor that causes a mechanical deterioration in physical properties.

In the present invention, a two-stage reaction system is generally used as a method for producing a polycarbonate by transesterification of a divalent hydroxy compound and a bisaryl carbonate. That is, a first-stage reaction in which a polycarbonate prepolymer is produced in a molten state by a transesterification reaction of the raw materials in the presence of a transesterification catalyst, and a second-stage reaction in which polymerization is further performed under a higher viscosity to obtain a high-molecular-weight polycarbonate.

In the first stage reaction (precondensation step), the reaction temperature is in the range of 100 ° C. to 300 ° C., preferably in the range of 130 ° C. to 280 ° C. 130 ° C
If the temperature is less than 280 ° C., the reaction rate becomes slow, and if it exceeds 280 ° C., side reactions tend to occur. After removing a predetermined distillate such as phenol under reduced pressure, the molecular weight is further increased in the second stage reaction (post-condensation step). The reaction temperature is 1
In the range of 80 ° C. to 350 ° C., preferably 200 ° C.
To 320 ° C. If the temperature is lower than 200 ° C., it is difficult to remove phenol and the like for measuring a high molecular weight,
If the temperature exceeds ℃, the coloring and side reaction of the resin are promoted, which is not desirable.

Further, this reaction is performed under a high vacuum, and the degree of vacuum is 10 Torr or less, preferably 1 Torr or less. As for the timing of adding the catalyst, it is also possible to use the appropriate catalyst for the initial batch charging or the first-stage reaction and the second-stage reaction.

Further, the present invention will be described in detail. In the post-condensation step, since the viscosity of the reaction system increases as the polycondensation reaction approaches completion, it is necessary to perform a treatment at a high temperature and increase the molecular weight. In order to measure the value, it was important to find a method capable of suppressing a side reaction (generation of a coloring source) due to oxidative deterioration or the like while distilling off by-products and the like.

The result of intensive study, that occupy to perform the polycondensation reaction in the range residence time in the post-condensation step below 55 minutes more than 15 minutes, further, two axes corresponding to the liquid thickness of the reaction solution
The clearance between the two stirring means of the extruder is 0.1 mm or more
It has been found that a colorless high molecular weight polycarbonate can be obtained by treating in the range of 50 mm.
Here, the residence time is a time that contributes to the polycondensation reaction under high vacuum and high temperature, and if it is less than 15 minutes, it is not enough to remove by-products, and high molecular weight is not obtained . Minute
When the number exceeds 3 , the coloring due to a side reaction or the like is highly likely to proceed, which is not preferable.

Further, from the viewpoint of efficiently removing by-products , two twin screw extruders corresponding to the liquid thickness of the reaction solution are used.
When the clearance of the stirring means is less than 0.1 mm, it is difficult to say that it is industrially economical, and when it is more than 50 mm, it is difficult to remove by-products. In addition, as an actual apparatus, a part corresponding to the liquid thickness in the reaction part is partially used.
The clearance between the two stirring means of the screw extruder is 0.1 mm
The present invention also includes a case where a distance of about 50 mm is present locally. Hereinafter, the present invention will be described in Examples,
The present invention is not limited to these examples.

[0025]

EXAMPLE 1 4566 g (20.0 mol) of bisphenol A, 4392 g (20.5 mol) of diphenyl carbonate and 0.489 g (0.4 mol) of 4-dimethylaminopyridine.
004 mol) and 0.039 g (0.00
(0.4 mol) was charged into a 20-liter stirred tank, and the atmosphere was replaced with nitrogen. Next, the pressure is reduced to 2 Torr while gradually increasing the temperature to 260 ° C., and phenol produced as a by-product is distilled off. After about 4 hours, a polycarbonate prepolymer having a viscosity average molecular weight of 13,000 was obtained.
Next, the obtained polycarbonate prepolymer was 280
A paddle type self-cleaning twin-screw extruder (L / D = 8.9, paddle rotation diameter 50 mm, shaft length 445.5 mm) controlled at 0.2 ° C. and 0.2 Torr, and a gear pump so that the residence time is 35 minutes. At 10
Discharged at 30 g / Hr. The viscosity average molecular weight of the obtained polymer was 28,000, and the hue was A ₃₈₀ -A
₅₈₀ = 0.08. The clearance (liquid thickness) of the twin-screw extruder is about 0.5 mm. Here, as a method of measuring the viscosity average molecular weight, the intrinsic viscosity [η] of the methylene chloride solution at 20 ° C. was measured using an Ubbelohde viscometer, and the viscosity average molecular weight (v) was calculated using the following equation.

[0026]

(Equation 1)

The evaluation of hue was based on the evaluation of polycarbonate as 1
As a 0% methylene chloride solution, 380μ with a UV measurement device
The difference between the absorbance in the wavelength range of m and 580 μm is measured and displayed, and the larger the value, the more the color is colored.

[0028]

Example 2 4566 g (20.0 mol) of bisphenol A, 4392 g (20.5 mol) of diphenyl carbonate and 0.489 g (0.089 g) of 4-methylaminopyridine
04 mol) and 0.078 g (0.000 g) of potassium acetate
8 mol) was charged into a 20-liter stirred tank, and the atmosphere was replaced with nitrogen. Next, the pressure is reduced to 2 Torr while gradually increasing the temperature to 260 ° C., and phenol produced as a by-product is distilled off. After about 4 hours, a polycarbonate prepolymer having a viscosity average molecular weight of 16,000 was obtained.
Next, the obtained polycarbonate prepolymer was 280
C., a paddle type self-cleaning twin-screw extruder controlled at 0.2 Torr and a residence time of 55
And discharged at 655 g / Hr with a gear pump. The viscosity average molecular weight of the obtained polymer is 34.0
00, and the hue was A ₃₈₀ −A ₅₈₀ = 0.09.

[0029]

COMPARATIVE EXAMPLE 1 Under the same conditions as in Example 1, the obtained polycarbonate prepolymer was fed into a horizontal biaxial polymerization machine controlled at 280 ° C. and 0.2 Torr, and was fed to a gear pump so that the residence time was 120 minutes. Discharged. The viscosity average molecular weight of the obtained polymer was 18,000, and the hue was A ₃₈₀ −A ₅₈₀ = 0.65.

[0030]

Comparative Example 2 Under the same conditions as in Example 1, the obtained polycarbonate prepolymer was fed into a screw evaporator controlled at 280 ° C. and 0.2 Torr, and discharged with a gear pump so that the residence time was 12 minutes. did. The viscosity average molecular weight of the obtained polymer was 16,000, and the hue was A ₃₈₀ −A ₅₈₀ = 0.45.

[0031]

Comparative Example 3 Under the same conditions as in Example 1, the obtained polycarbonate prepolymer was fed into a twin screw extruder controlled at 280 ° C. and 0.2 Torr, and adjusted with a gear pump so that the residence time was 180 ° C. , Was discharged. The viscosity average molecular weight of the obtained polymer is 35,000.
However, the hue was A ₃₈₀ −A ₅₈₀ = 1.20, and a partially black kogation was observed.

[0032]

According to the present invention, a colorless, transparent, high-molecular-weight polycarbonate can be industrially efficiently produced.

Claims (3)

(57) [Claims] 1. A divalent hydroxy compound and bisaryl carbonate melt polycondensation by transesterification method, Po
In a method for producing a carbonate , a polycarbonate having a viscosity average molecular weight of 5,000 to 20,000 is subjected to a reaction temperature of 180 to 350 ° C.
A method for producing a polycarbonate, comprising conducting a polycondensation reaction with a twin-screw extruder at a force of 10 Torr or less and a residence time of 15 to 55 minutes . 2. The two-screw extruder according to claim 1, which corresponds to the thickness of the reaction solution in the reaction section in the post-condensation step.
A method for producing a polycarbonate, wherein a polycondensation reaction is performed in a clearance of a stirring means in a range of 0.1 mm to 50 mm. 3. The method for producing a polycarbonate according to claim 1, wherein the divalent hydroxy compound is any compound represented by the following general formula . Embedded image (R ₁ , R ₂ , R ₃ , and R ₄ each represent a hydrogen atom,
8 represents a straight-chain or branched alkyl group or a phenyl group, and X is a halogen atom, wherein n = 0 to 4, and m = 1 to 4. )