JPH05117383A - Production of polycarbonate - Google Patents

Abstract

PURPOSE:To obtain a clear and colorless polycarbonate having high product stability by carrying out melt-polycondensation of a bivalent hydroxy compound with a bisaryl carbonate in the presence of an ester-interchange catalyst while controlling the amount of potassium in the system. CONSTITUTION:A clear and colorless polycarbonate having high product stability and a potassium content of <=100ppm is produced by carrying out the ester- interchange reaction of (A) a bivalent hydroxy compound [e.g. 2,2-bis-(4- hydroxyphenyl)propane] with (B) a bisaryl carbonate (e.g. bisphenyl carbonate) in the presence of (C) an ester-interchange catalyst (e.g. 4-diethylaminopyridine) in nitrogen atmosphere at 100-300 deg.C (preferably 130-280 deg.C), raising the temperature while gradually decreasing the pressure to effect the polycondensation reaction at 180-350 deg.C (preferably 200-320 deg.C) and removing the produced phenol. The above process is carried out while controlling the amount of potassium (K) in the polymerization system to 0.1-100ppm.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polycarbonate by a transesterification method and a polycarbonate obtained by the transesterification method.

[0002]

BACKGROUND OF THE INVENTION Polycarbonates are versatile engineering thermoplastics having a wide range of applications, especially for injection molding or as sheet glass alternatives to glazings.

Conventionally, an interfacial polycondensation method, a transesterification method and the like have been applied to the production of these polycarbonates.
The interfacial polycondensation method is generally effective in producing polycarbonate, but has drawbacks such as the use of toxic phosgene and the fact that chlorine ions remain in the polycarbonate produced.

In the transesterification reaction, a transesterification catalyst is added to diphenyl carbonate and an aromatic dihydroxy compound to synthesize a prepolymer while distilling phenol under heating and reduced pressure, and finally under high vacuum, 290
High-molecular-weight polycarbonate is obtained by distilling phenol by heating above ℃ (US Pat. No. 4,345,062).
Specification).

Since the transesterification method can perform the reaction by melt polycondensation and is an industrially economical method, various studies have been made. In particular, patented processes related to catalysts, patents related to devices, and the like have been proposed. However, from an industrial point of view, in the method for producing a transesterified polycarbonate, it is difficult to say that sufficient technology has been established in terms of controlling the molecular weight, suppressing side reactions, and thermal stability of the product. ..

[0006]

Means for Solving the Problems In the method for producing a transesterification polycarbonate, the present inventors have conducted extensive research in order to produce a polycarbonate having excellent thermal stability by suppressing side reactions and having a molecular weight as designed. As a result, they have found that these can be achieved by controlling the potassium (K) content present in the polymerization system.

That is, the potassium compound is an effective catalyst for the transesterification reaction, but in addition to the activity for the transesterification reaction, it also has the activity for side reactions such as decarboxylation reaction and Conveschmitt reaction. Therefore, when the potassium compound is present in a high concentration in the polymerization system, branching / crosslinking reactions caused by these side reactions occur to a nonnegligible level, and as a result, a polycarbonate having a wide molecular weight distribution is obtained. Furthermore, if the polymer contains a high concentration of potassium, it may cause a decrease in the molecular weight or coloring during heating.

According to the present invention, when a polycarbonate is produced from a divalent hydroxy compound and a bisaryl carbonate by a transesterification method, by controlling the potassium content, a side reaction is suppressed and a colorless transparent material having excellent thermal stability is obtained. The present invention relates to a method for producing a polycarbonate.

Examples of the divalent hydroxy compound used in the present invention include compounds represented by Chemical formulas 1 to 4.

[0010]

[Chemical 1]

[0011]

[Chemical 2]

[0012]

[Chemical 3]

[0013]

[Chemical 4]

(In the formula, each of R ₁ , R ₂ , R ₃ and R ₄ R ₅ represents 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, m = 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-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 can be mentioned. Furthermore, it is also possible to produce a copolycarbonate by combining two or more divalent hydroxy compounds.

Typical examples of the transesterification catalyst that can be used in the present invention include (a) metal-containing catalysts such as aluminum borohydride, titanium borohydride, tin borohydride and germanium borohydride. ,
Tin oxide (tetravalent), dibutyltin oxide, germanium hydroxide, tin acetate (tetravalent), germanium acetate, tin carbonate (tetravalent), germanium carbonate, tin nitrate (tetravalent),
Examples thereof include germanium nitrate, antimony trioxide, bismuth trimethylcarboxylate and the like.

(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.

Further, (c) carbonic acid, acetic acid, formic acid, nitric acid, nitrous acid, oxalic acid, fluoroboric acid, hydrofluoric acid salt and the like of the above-mentioned electron donating amine compound may be mentioned. (D) As a catalyst similar to the electron-donating phosphorus compound, triethylphosphine, tri-n-propylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, tri-o-dimethoxyphenylphosphine, tri-p -Tolylphosphine, tri-o-tolylphosphine, tributylphosphite, triphenylphosphite, tri-p-tolylphosphite, tri-o-tolylphosphite and the like can be mentioned.

Further, as a catalyst similar to (e) borane complex, a complex of borane and the following compounds, that is, ammonia, dimethylamine, trimethylamine, triethylamine, t-butylamine, dimethylaniline, pyridine, dimethylaminopyridine, morpholine, Examples thereof include complexes such as piperazine, pyrrole, tetrahydrofuran, dimethyl sulfide, tri-n-butylphosphine, triphenylphosphine and triphenylphosphite.

These catalysts may be used alone or in combination of two or more, and the amount thereof used is usually in the range of 1 × 10 ^-6 to 1 mol based on the divalent hydroxy compound. However, it is preferably 5 × 10 ⁻⁵
Is about 5 × 10 ^-2 mol. If the amount is less than 5 × 10 ⁻⁵ mol, the polymerization rate will be slow, which will cause coloring. When the amount exceeds 5 × 10 ^-2 mol, the catalyst remaining in the obtained polycarbonate has a bad influence on the physical properties, for example, becomes a factor of mechanically lowering the physical properties.

Further, typical examples of bisaryl carbonate include diphenyl carbonate and bis (2,4-
Dichlorophenyl) carbonate, bis (2,4,6-
Trichlorophenyl) carbonate, bis (2-cyanophenyl) carbonate, bis (o-nitrophenyl)
Examples thereof include bisaryl carbonates having unsubstituted and nuclear substituents such as carbonate and ditolyl carbonate.

In the present invention, a two-step 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, it is a first-stage reaction in which a polycarbonate prepolymer is produced in a molten state by a transesterification reaction of the above raw materials in the presence of an transesterification catalyst, and a second-stage reaction in which polymerization is further advanced 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 130 ° C. to 280 ° C. 130 ° C
If it is lower than 280 ° C., the reaction rate becomes slow, and if it exceeds 280 ° C., a side reaction easily occurs. After removing predetermined distillates such as phenol under reduced pressure, the second stage reaction (post-condensation step)
With this, higher molecular weight can be achieved. As the reaction temperature,
In the range of 180 ° C to 350 ° C, preferably 200
It is in the range of ℃ to 320 ℃. If the temperature is less than 200 ° C, it is difficult to remove phenol and the like in order to obtain a high molecular weight.
When the temperature exceeds 0 ° C, coloring and side reactions of the resin are promoted, which is not desirable.

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

The present invention is described below with reference to examples, but the present invention is not limited to these examples.

[0025]

Example 1 Hastelloy C-276 (Ni 59%, C
r 15.5%, Mo 16%, Fe 5.5%, W
3.8%) in a reaction vessel made of 2,2-bis (4-hydroxyphenyl) propane 22.8 g (0.1 mol), bisphenyl carbonate 21.9 g (0.1023 mol) and 4-dimethylaminopyridine. 0.0024g
(2 × 10 ^-5 mol) was added, and the mixture was added at 180 ° C. under a nitrogen atmosphere to 1
After stirring for an hour, the temperature was gradually reduced while raising the temperature, and finally a polycondensation reaction was performed at 0.1 Torr and 270 ° C. for 2 hours to distill off the produced phenol to obtain a colorless transparent polycarbonate. The viscosity-average molecular weight of the polycarbonate obtained was Mv = 30,000, Mw / Mn = 2.75, had a hue A ₃₈₀ -A ₅₈₀ = 0.08. Here, the viscosity average molecular weight is measured by measuring the intrinsic viscosity [η] of the methylene chloride solution at 20 ° C. using an Ubbelohde viscometer,
The viscosity average molecular weight Mv was calculated using the following formula. [Η] = 1.11 × 10 ⁻⁴ (Mv) ^0.82 The molecular weight distribution Mw / Mn was measured by a usual gel permeation chromatographic method at 40 ° C. using a 0.5 wt% chloroform solution. The hue was evaluated by using a 10% methylene chloride solution of polycarbonate and measuring the difference in absorbance in the wavelength region of 380 μm and 580 μm with a UV measuring device and displaying it. The larger the value, the more colored it is. In addition, K in the obtained polycarbonate
The content was 0.3 ppm.

[0026]

Example 2 Using a Pyrex glass flask, the reaction was carried out in the same manner as in Example 1. The viscosity average molecular weight of the obtained polycarbonate is Mv = 31,000, Mw.
/Mn=2.69, was a hue A ₃₈₀ -A ₅₈₀ = 0.07. The K content in the polycarbonate was 15 ppm.

[0027]

Example 3 Pyrex glass flask with 2,2-
22.8 g of bis (4-hydroxyphenyl) propane
(0.1 mol), bisphenyl carbonate 21.9 g
(0.1023 mol) and 4-dimethylaminopyridine 0.0024 g (2 x 10 ^-5 mol), potassium acetate 0.
0002 g (2 × 10 ⁻⁶ mol) was added and the reaction was carried out in the same manner as in Example 1. The viscosity average molecular weight of the obtained polycarbonate is Mv = 34,000, Mw / Mn = 2.
80, it was a hue A ₃₈₀ -A ₅₈₀ = 0.08. The K content in the polycarbonate was 40 ppm.

[0028]

Comparative Example 1 The reaction was performed in the same manner as in Example 1 except that 0.0138 g (1 × 10 ⁻⁴ mol) of potassium carbonate was further added in the initial charging. The viscosity average molecular weight of the obtained polycarbonate is Mv = 45,000, Mw
/Mn=3.80, was hue A _{38 0} -A ₅₈₀ = 2.4. The K content in the polycarbonate was 140 ppm.

[0029]

Comparative Example 2 The reaction was performed in the same manner as in Example 2 except that 0.0023 g (4 × 10 ⁻⁵ mol) of potassium hydroxide was further added during the initial charging. The viscosity average molecular weight of the obtained polycarbonate is Mv = 5.
2,000, Mw / Mn = 4.20, hue A ₃₈₀ -A
₅₈₀ = 2.7. The K content in the polycarbonate was 115 ppm.

[0030]

Comparative Example 3 In Example 3, the amount of potassium acetate was adjusted to 0.
The reaction was carried out in the same manner except that the amount was 1 g (1 × 10 ⁻³ mol). The viscosity average molecular weight of the obtained polycarbonate is Mv = 67,000, Mw / Mn = 5.70, hue A
₃₈₀ - _A580 = 3.4. The K content in the polycarbonate was 1200 ppm.

Further, the polycarbonates obtained in the respective Examples and Comparative Examples were subjected to (1) a heat aging test at 160 ° C. for 10 days and (2) a hydrolysis test at 90 ° C. and 100% humidity for 10 days. The degree of decrease in molecular weight was evaluated by the following polymer cleavage rate.

[0032]

[Equation 1]

Here, Mv ₀ represents the viscosity average molecular weight of the sample before the treatment, and Mv ₁₀ represents the viscosity average molecular weight of the sample after 10 days.

[0034]

[Table 1]

The number of cuts 1.0 means that each polymer chain is cut once on average to have a molecular weight of 1/2.

[0036]

Industrial Applicability According to the present invention, it is possible to industrially produce a colorless and transparent polycarbonate having good product stability.

Claims (2)

[Claims] 1. A method for producing a polycarbonate by melt-polycondensing a divalent hydroxy compound and a bisaryl carbonate by a transesterification method in the presence of a transesterification catalyst, and reacting in the presence of a K content of 0.1 to 100 ppm. Characteristic polycarbonate production method. 2. A polycarbonate obtained by a transesterification method, having a K content of 100 ppm or less.