JP3359782B2 - Method for producing aromatic polycarbonate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an aromatic polycarbonate, and more particularly to a method for producing an aromatic polycarbonate having an improved gel and color tone.

[0002]

2. Description of the Related Art Polycarbonate resins obtained from the interfacial polycondensation of an aromatic dihydroxy compound and phosgene are widely used for various purposes due to their excellent mechanical and thermal properties, but utilize toxic phosgene. Therefore, there is a problem in safety, and the use of methylene chloride as a solvent has many problems such as environmental destruction. Therefore, transesterification methods that do not use methylene chloride or phosgene have been spotlighted, but the polycarbonate resins obtained by the transesterification method are subject to long-term heat histories at high temperatures, resulting in many gels and poor quality, such as poor color tone. Was not obtained. For this reason, several attempts have been made to produce high-quality polycarbonate by the transesterification method.

[0003] In the production of polycarbonate by the transesterification method, an alkali metal compound or an alkaline earth metal compound is usually used as a catalyst. However, when a large amount of these catalysts is used, the color tone of the obtained polymer deteriorates. The gel is also contained in a large amount, which is not preferable. on the other hand,
When the amount of these catalysts is reduced, the quality of the polymer obtained is somewhat improved, but the polymerization time is extremely long, which is economically disadvantageous and the quality cannot be sufficiently improved.

[0004] For this reason, it has been proposed to use another catalyst in combination. For example, Japanese Patent Publication No. 47-14742 discloses a method using a quaternary ammonium compound. Also, Japanese Patent Application Laid-Open No. 2-124934 discloses a method using a nitrogen-containing basic compound. However, according to these methods, sufficient polymerization activity cannot be obtained, and the problem has not been solved.

Further, JP-A-5-17564 discloses a method in which a nitrogen-containing basic compound is added in multiple stages in the presence or absence of a trace amount of an alkali metal or an alkaline earth metal. However, this method still has insufficient polymerization activity, and there is a need for a method for economically obtaining high-quality polycarbonate.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a high-quality polycarbonate resin in a short polymerization time by a transesterification method.

[0007]

According to the study of the present inventors, when an aromatic polycarbonate is produced by transesterification between an aromatic dihydroxy compound and an aromatic diester carbonate, a preferable catalyst concentration is determined according to the degree of polymerization. Became different. Therefore, the above-mentioned problem is solved by performing the transesterification reaction in multiple stages and setting the optimum catalyst concentration in each stage.

That is, the present invention provides a method for producing an aromatic polycarbonate by subjecting an aromatic dihydroxy compound and an aromatic carbonic acid diester to transesterification in multiple stages in the presence of a catalyst, wherein the intrinsic viscosity of the polymer is 0.35 or less. An aromatic polycarbonate characterized in that the concentration of the alkali metal compound and / or the alkaline earth metal compound catalyst is lowered in the low polymerization degree region and is increased in the high polymerization degree region where the intrinsic viscosity of the polymer exceeds 0.35. It is a manufacturing method.

As the polymerization catalyst used in the present invention, an alkali metal compound and / or an alkaline earth metal compound is used.

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, and lithium acetate. , Sodium stearate, potassium stearate, lithium stearate, sodium salt, potassium salt, lithium salt of bisphenol A, sodium benzoate, potassium benzoate, lithium benzoate and the like.

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, barium carbonate, Examples include magnesium, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate, calcium stearate, barium stearate, magnesium stearate, strontium stearate and the like.

Although these catalysts have a stronger polymerization catalytic activity than nitrogen-containing basic compounds, they are also considered to have a strong ability to cause undesired reactions such as a coloring reaction and a gel formation reaction. When used, it has been practiced at a low concentration at the expense of polymerization rate.

For example, in the method disclosed in JP-A-5-17564, a multistage catalyst addition similar to the present invention is employed, but the catalyst used is an alkali metal compound or an alkaline earth metal compound. It contains an extremely small amount, and a nitrogen-containing basic compound is a main constituent of the catalyst.

However, as described above, the nitrogen-containing basic compound has only a weak polymerization ability particularly in the latter stage of the polymerization, so that a satisfactory polymerization time cannot be achieved even though the catalyst is additionally added, The quality was also inadequate.

In the present invention, it is extremely important to select an optimum catalyst concentration according to the degree of polymerization. As a result of the study by the present inventors, the following has been surprisingly revealed.

The relationship between the catalyst concentration and the undesired side reaction varies depending on the degree of polymerization. In the low polymerization degree region where the intrinsic viscosity at the beginning of polymerization is 0.35 or less, the side reaction becomes severe when the catalyst concentration is high. However, in the high polymerization degree region where the intrinsic viscosity exceeds 0.35, when the catalyst concentration is increased, the polymerization rate is greatly improved, but the side reaction rate is not so much improved. It was found that, contrary to what had been done, the higher the catalyst concentration was, the lower it was.

In the low polymerization degree region where the intrinsic viscosity is 0.35 or less, the polymerization rate does not depend much on the catalyst concentration.
It has been found that a sufficient polymerization rate can be obtained even at a low catalyst concentration at which the quality does not deteriorate.

That is, in the present invention, the intrinsic viscosity is 0.1.
35 or less, preferably 0.20 or less
The concentration of the medium was 1 × with respect to 1 mole of the aromatic dihydroxy compound.
10 ^-7~ 1 × 10^-FiveEquivalent, preferably 5 × 10^-7~ 5x
10^-6Equivalent, high degree of polymerization with intrinsic viscosity exceeding 0.35
From the beginning, the catalyst concentration of the
1 × 10^-6~ 3 × 10^-FourEquivalent,
Preferably 5 × 10^-6~ 1 × 10^-FourPerform in equivalent. This
As a result, excellent polymerization quality can be achieved in a short polymerization time.
It becomes possible to produce polycarbonate.

In the present invention, a relatively mild transesterification catalyst other than an alkali metal compound or an alkaline earth metal compound can be used as an auxiliary catalyst.

As such an auxiliary catalyst, there is a nitrogen-containing basic compound, which can be used in both a low-polymerization region and a high-polymerization region. Particularly, a low concentration of an alkali metal compound or an alkaline earth metal compound is used. When used in the polymerization degree region, favorable results can be obtained.

Examples of the nitrogen-containing basic compound include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, trimethylbenzylammonium hydroxide, trimethylamine, triethylamine, dimethylbenzylamine, triphenylamine and the like.

The amount of the nitrogen-containing basic compound used is 2.5 × 10 ^-6 to 2.
It is preferable to add 5 × 10 ⁻³ mol.

Further, if necessary, another substance can be used as an auxiliary catalyst.

Such substances include alkali metal or alkaline earth metal salts of hydroxides of boron and aluminum,
Quaternary ammonium salts, alkoxides of alkali metals and alkaline earth metals, organic acid salts of alkali metals and alkaline earth metals, zinc compounds, boron compounds, silicon compounds, germanium compounds, organotin compounds,
Normal esterification reaction of lead compounds, osnium compounds, antimony compounds, zirconium compounds, etc.
The catalyst used for the transesterification can be used, but is not limited thereto. When using an auxiliary catalyst, only one type may be used or two or more types may be used in combination.

In the present invention, there is no particular limitation on how to add the above-mentioned catalysts and auxiliary catalysts. For example, they may be added alone, may be added by blending with polycarbonate, or may be dissolved in a solvent. May be added. When a solvent is used, it is preferable to use water and an aromatic hydroxy compound as the solvent.

The aromatic dihydroxy compound used in the present invention is not particularly limited. For example, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) butane, 2-bis (4
-Hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 1,1-bis (4-hydroxy-t-butylphenyl) propane, etc. Bis (hydroxyaryl) alkanes, 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1
Bis (hydroxyaryl) cycloalkanes such as bis (hydroxyphenyl) cyclohexane, 4,4 ′
-Dihydroxyaryl ethers such as dihydroxydiphenyl ether; dihydroxyaryl sulfides such as 4,4'-dihydroxydiphenyl sulfide; dihydroxyaryl sulfoxides such as 4,4'-dihydroxydiphenyl sulfoxide; 4,4'-
Dihydroxyaryl sulfones such as dihydroxydiphenyl sulfone and mixtures thereof are used.
In particular, 2,2-bis (4-hydroxyphenyl) propane is preferable, and other aromatic dihydroxy compounds can be used in an amount of 2 to 20 mol% of the whole.

Examples of the aromatic carbonic acid diester used in the present invention include esters which may be substituted, such as an aryl group having 6 to 10 carbon atoms and an aralkyl group. Specifically, diphenyl carbonate, ditolyl carbonate,
Bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate and the like can be mentioned.

In the production of the polycarbonate in the present invention, the aromatic diester carbonate is used in an amount of 1.00 to 1.30 per mole of the aromatic dihydroxy compound.
Mol, preferably in an amount of from 1.005 to 1.10 mol.

In the transesterification reaction between the aromatic dihydroxy compound and the aromatic carbonic acid diester according to the present invention, the aromatic monohydroxy compound formed by stirring while heating under an inert gas atmosphere is distilled off as is conventionally known. It is done by letting it go out. In the low polymerization degree region, the reaction temperature is 100 to 2
The reaction is preferably performed at 60 ° C. and a reaction pressure of 1 to 500 Torr, and in a high polymerization degree region, the reaction temperature is 200 to 300 ° C. and the reaction pressure is 0.1 to 10 Torr.

The type of the transesterification reaction of the present invention is not particularly limited, and the transesterification reaction may be carried out batchwise or continuously. The reactor used may be a tank type, a tube type, or a tower type.

[0031]

According to the present invention, an aromatic polycarbonate having a small amount of gel and a good hue can be produced in a short time by using a transesterification reaction.

[0032]

The present invention will be described below in detail with reference to examples. The percentages and parts in the examples are by weight unless otherwise specified.
Or parts by weight. In the following examples, physical properties and the like of polycarbonate were measured as follows.

Intrinsic viscosity: A 0.7 g / dl methylene chloride solution was measured using an Ubbelohde viscometer.

Pellet color: Measured with a color difference meter manufactured by Nippon Denshoku Industries.

Example 1 Diphenyl carbonate was charged into a melting tank equipped with a stirrer at a ratio of 1.03 mol per mol of 2,2-bis (4-hydroxyphenyl) propane, and dissolved at 150 ° C. after purging with nitrogen. And the molten mixture is
It was transferred to a raw material storage tank maintained at 50 ° C.

Next, rectification is provided, and the internal temperature is set to 180 ° C.
The molten mixture was continuously supplied at a rate of 60 kg / hour to a rigid stirring tank whose internal temperature was maintained at 30 Torr,
For 1 mol of 2,2-bis (4-hydroxyphenyl) propane, 2 × 10 ⁻⁶ equivalents of bisphenol A disodium salt as a catalyst and 1 × 10 ⁻⁴ mol of tetramethylammonium hydroxide as a co-catalyst were added to phenol / Water =
The reaction was carried out while continuously supplying 9/1 as a solvent while removing generated phenol from the rectification column.

The obtained reaction product was continuously supplied to another rigid stirred tank having an internal temperature of 270 ° C. and an internal pressure of 1 Torr, and the reaction was further continued while distilling off phenol.
The obtained reaction product was continuously extracted using a gear pump. As a result, a prepolymer having an intrinsic viscosity of 0.35 was obtained.

Next, the prepolymer was heated at an internal temperature of 270 ° C.
The internal pressure was continuously supplied to a horizontal twin-screw reactor maintained at 1 Torr, and 1.8 × 10 4 mol of 2,2-bis (4-hydroxyphenyl) propane supplied to the first tank was used.
^-5 equivalents of bisphenol A disodium salt is continuously supplied to the reactor as a master chip (a prepolymer containing 0.0003 equivalents of disodium bisphenol A) to further polymerize while removing generated phenol out of the system. Thereby, a polycarbonate having an intrinsic viscosity of 0.6 was continuously obtained. The average residence time during this period was 0.7 hours, and the pellet color of the obtained polycarbonate was L =
64.3, b = 0.2, and the number of microgels (hereinafter referred to as microgels) insoluble in methylene chloride present in 0.5 Kg of 100 μm or less, which was insoluble in methylene chloride, was 4 and good.

Example 2 The operation was performed in the same manner as in Example 1 except that the catalyst supplied to the horizontal twin-screw reactor was a phenol solution. The intrinsic viscosity of the obtained polycarbonate is 0.5
9. The pellet color was L = 63.8, b = -0.1, and there were two microgels.

Comparative Example 1 Same as Example 1 except that the amount of bisphenol A disodium salt supplied to the first tank was 2 × 10 ⁻⁵ equivalent and the supply of the catalyst to the horizontal twin-screw reactor was stopped. Operated. The intrinsic viscosity of the obtained polycarbonate was 0.61, the pellet color was L = 62.3, and b = 2.
0 and 20 microgels. Although the polymerization rate was high, the quality was inferior.

[Comparative Example 2] The amount of the catalyst supplied to the first tank was 5 × 10 ^-7 equivalent of bisphenol A disodium salt and 1 × 10 ^-4 mol of tetramethylammonium hydroxide. The operation was performed in the same manner as in Example 1 except that the amount of the supplied catalyst was 1 × 10 ⁻⁴ mol of tetramethylammonium hydride. The inherent viscosity of the obtained polycarbonate was 0.43, the pellet color was L = 62.3,
b = 0.6 and there were four microgels. Example 1
Although the quality was slightly inferior to that of, the polymerization rate was significantly inferior.

Continuation of front page (72) Inventor Katsushi Sasaki 2-1 Hinode-machi, Iwakuni-shi, Yamaguchi Prefecture Teijin Limited Iwakuni Research Center (56) References JP-A-4-122727 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C08G 64/00-64/42

Claims (8)

(57) [Claims] 1. A method for producing an aromatic polycarbonate by subjecting an aromatic dihydroxy compound and an aromatic carbonic acid diester to transesterification in the presence of a catalyst in multiple stages, wherein the polymer has an intrinsic viscosity of 0.35 or less. A method for producing an aromatic polycarbonate, characterized by lowering the concentration of an alkali metal compound and / or an alkaline earth metal compound catalyst in a region and increasing the concentration in a high polymerization degree region where the intrinsic viscosity of a polymer exceeds 0.35. 2. An alkali metal compound in a low polymerization degree region and
And / or the concentration of alkaline earth metal compound catalyst
1 × 10 per mole of dihydroxy compound ^-7~ 1 × 1
0^-FiveAnd the concentration in the high polymerization area is the total amount from the beginning.
And 1 × 10 5 per mole of the aromatic dihydroxy compound
^-6~ 3 × 10^-FourClaim 1 characterized by the equivalent
The manufacturing method as described. 3. The reaction is performed at a reaction temperature of 100 to 260 ° C. and a reaction pressure of 1 to 500 Torr in a low polymerization degree region using 1 to 1.3 mol of an aromatic carbonic diester per 1 mol of an aromatic dihydroxy compound. The reaction temperature in the high polymerization degree region is 200 to 300 ° C., and the reaction pressure is 0.1 to 10 Torr.
The method according to claim 1, wherein the method is performed. 4. The method according to claim 1, wherein the alkali metal compound is a sodium compound, a potassium compound, or a lithium compound, and the alkaline earth metal compound is a calcium compound, a magnesium compound, or a barium compound. 5. The method according to claim 1, wherein the alkali metal compound and the alkaline earth metal compound are used as a solution of water and / or an aromatic hydroxy compound. 6. The process according to claim 1, wherein the alkali metal compound and the alkaline earth metal compound are used as a mixture with polycarbonate and / or a prepolymer thereof. 7. The method according to claim 1, wherein the aromatic dihydroxy compound is 2,2-
The production method according to any one of claims 1 to 6, wherein the production method is bis (4-hydroxyphenyl) propane. 8. The aromatic carbonic diester is at least one selected from the group consisting of diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate and bis (diphenyl) carbonate. The production method according to any one of claims 1 to 7.