JP2000136240A - Production of polycarbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently produce the subject polycarbonate with improved tint by subjecting dihydroxy compound and carbonic diester to the multi-step poly- condensation reaction between them in which different catalysts are used in the first step reaction and in the second step reaction. SOLUTION: When (A) dihydroxy compound and (B) carbonic diester are subjected to multi-step polycondensation reaction with two or more steps, (C) 1×10-7-1×10-1 mole, per mole of the component A, of a catalyst comprising an ammonium compound and/or a phosphonium compound is used in the first step, and (D) a catalyst comprising alkali metal or alkaline earth metal phosphorus-containing inorganic salt is used in the second step, preferably in an amount of 1×10-7-1×10-6 mole per mole of the component A. As the component C, are preferably cited a quaternary ammonium compound and quaternary phosphonium compound. The first polycondensation step is preferably carried out at a temperature <=270 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polycarbonate by a transesterification reaction. More specifically, the present invention relates to a method for producing a high-molecular-weight aromatic polycarbonate having an improved color tone by a transesterification reaction between an aromatic dihydroxy compound and a carbonic acid diester compound.

[0002]

BACKGROUND OF THE INVENTION In recent years, aromatic polycarbonates have been widely used in many fields as engineering plastics having excellent mechanical properties such as impact resistance and heat resistance and transparency.

As a method for producing this aromatic polycarbonate, a so-called phosgene method in which an aromatic dihydroxy compound such as bisphenol is reacted with phosgene by an interfacial polycondensation method has been industrialized. However, the phosgene process that is currently practiced industrially requires the use of highly toxic phosgene, the problem of treating sodium chloride, which is a large amount of by-product, and the hygiene problem of methylene chloride, which is usually used as a reaction solvent. And air quality issues,
Many problems have been pointed out.

As a method of producing an aromatic polycarbonate other than the phosgene method, there is known a method of performing a transesterification reaction between an aromatic dihydroxy compound and a carbonic acid diester using an alkali metal compound such as sodium hydroxide as a catalyst (melting method). ing. This method has an advantage that an aromatic polycarbonate can be produced at a low cost, and does not use toxic substances such as phosgene and methylene chloride.

When producing polycarbonate by such a melting method, in order to obtain a high-molecular-weight polycarbonate having excellent mechanical properties, an unreacted monomer such as bisphenol or diphenyl carbonate is prepared from a high-viscosity polycarbonate melt. It is necessary to distill. For this reason, the polycarbonate produced is usually 25
It will be exposed for a long time at a high temperature of 0 to 330 ° C.
However, an alkali metal compound such as sodium hydroxide acts as a catalyst for the transesterification reaction, and may also cause side reactions such as a decarboxylation reaction and a Kolbe-Schmitt-like reaction. Polycarbonate represented by or causes a crosslinked product to be formed, and further causes a coloration of the produced polycarbonate, and in general, in the melting method, excellent quality of the balance of color tone and molecular weight is obtained. There was a problem that it was difficult to obtain a product ("Polycarbonate resin" published by Nikkan Kogyo Shimbun, September 30, 1969).

[0006]

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In order to solve these problems, for example, JP-A-4-89824 discloses (1) a nitrogen-containing basic compound, (2) an alkali metal compound or an alkaline earth metal compound, and (3) ) Discloses a catalyst comprising boric acid or borate ester, and JP-A-4-46928 discloses (1) an electron-donating amine compound, and (2) a catalyst comprising an alkali metal compound or an alkaline earth metal compound. Further, Japanese Patent Application Laid-Open No. 4-175368 discloses a method in which melt polymerization is carried out in the presence of an alkaline compound catalyst, and then an acidic compound and an epoxy compound are added to the obtained reaction product.

However, in the above method, the improvement of problems such as coloring was not always satisfactory. Further, JP-A-7-53704 also discloses a method for producing a polycarbonate in which side reactions are suppressed and the hue is improved, (1) (a) an alkali metal compound or an alkaline earth metal compound and (d) non-volatile A single compound formed from the acid of
Or (2) a mixture of (a) an alkali metal compound or an alkaline earth metal compound and (b) a non-volatile acid,
Further, a method for producing a polycarbonate using the single compound or the mixture showing a weak acidity in an aqueous solution as a catalyst is disclosed, but the hue polymerization rate of the obtained polycarbonate was not sufficiently satisfactory. .

[0009] In view of these problems, the present inventors have
As a result of intensive research, when producing a polycarbonate by transesterification using a dihydroxy compound and a carbonic acid diester as raw materials, the transesterification reaction is carried out in two or more multistage polycondensation steps, and the first polycondensation step is carried out. In at least one compound selected from the group consisting of (a) an ammonium compound and a phosphonium compound as a catalyst, and (b) an alkali metal phosphorus-containing inorganic salt and / or an alkaline earth metal in the second and subsequent polycondensation steps It has been found that by using a phosphorus-containing inorganic salt as a catalyst, a side reaction can be suppressed and a polycarbonate having an improved hue can be efficiently produced, and the present invention has been completed.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and provides a method for producing a polycarbonate capable of efficiently producing a polycarbonate having suppressed side reactions and improved hue. It is an object.

[0011]

SUMMARY OF THE INVENTION The process for producing a polycarbonate according to the present invention is characterized in that, when a polycarbonate is produced by a transesterification reaction using a dihydroxy compound and a diester carbonate as raw materials, the transesterification reaction is carried out in two or more multistage polycondensation steps; In the first polycondensation step, (a) at least one compound selected from ammonium compounds and phosphonium compounds is used as a catalyst, and in the second and subsequent polycondensation steps, (b) an alkali metal phosphorus-containing inorganic It is characterized in that a salt and / or an alkaline earth metal-containing inorganic salt containing phosphorus is used as a catalyst.

In the method for producing a polycarbonate according to the present invention, the first-stage polycondensation step is preferably performed at a temperature of 270 ° C. or lower. In the present invention, (a) at least one compound selected from an ammonium compound and a phosphonium compound is used in an amount of 1 × 10 ^-7 to 1 × 10 ^-1 mol per ¹ mol of the dihydroxy compound, b) It is preferable to use a salt composed of an alkali metal phosphorus-containing inorganic salt and / or an alkaline earth metal phosphorus-containing inorganic salt in an amount of 1 × 10 ⁻⁷ to 1 × 10 ⁻⁶ mol.

Furthermore, the amount of the alkali metal compound and / or the alkali metal earth compound contained as impurities in the raw material is 1 to 1 mol of the dihydroxy compound.
It is preferable that the amount is not more than × 10 ⁻⁷ mol.

(A) at least one compound selected from an ammonium compound and a phosphonium compound,
It is preferably at least one compound selected from the group consisting of quaternary ammonium compounds and quaternary phosphonium compounds.

[0015]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the method for producing a polycarbonate according to the present invention will be specifically described. First, the polycondensation raw material used in the method for producing a polycarbonate according to the present invention will be described.

Polycondensation raw material In the production method according to the present invention, a dihydroxy compound and a carbonic acid diester are used as the polycondensation raw material.

The dihydroxy compound used in the present invention is not particularly limited, and for example, bisphenols represented by the following formula [I] are used.

[0018]

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As the bisphenols represented by the above formula [I], specifically, 1,1-bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane (hereinafter bisphenol A), 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl)
Octane, 1,1-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) n-butane, bis (4-hydroxyphenyl) phenylmethane, 2,2-bis (4-hydroxy- 1-methylphenyl) propane, 1,1-bis (4-hydroxy-t-butylphenyl) propane, 2,2-
Bis (hydroxyaryl) alkanes such as bis (4-hydroxy-3-bromophenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclopentane, and 1,1-bis (4-hydroxyphenyl) cyclohexane And bis (hydroxyaryl) cycloalkanes.

In the present invention, in the above formula, X is -O-,
Bisphenols such as —S—, —SO— or —SO ₂ — are also exemplified, and, for example, bis (4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxy-3,3′-dimethylphenyl ether, etc. Hydroxyaryl) ethers, 4,4′-dihydroxydiphenyl sulfide,
Bis (hydroxydiaryl) sulfides such as 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide;
Bis (hydroxydiaryl) sulfoxides such as 4,4'-dihydroxydiphenylsulfoxide and 4,4'-dihydroxy-3,3'-dimethyldiphenylsulfoxide;4,4'-
Dihydroxydiphenyl sulfone, 4,4'-dihydroxy-
Bis (hydroxydiaryl) sulfones such as 3,3′-dimethyldiphenylsulfone can also be mentioned.

The bisphenols represented by the following formula [II]
The compound shown by these is also mentioned.

[0022]

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(Wherein, R ^f is a halogen atom, a hydrocarbon group having 1 to 10 carbon atoms or a halogen-substituted hydrocarbon group, and n is an integer of 0 to 4. When n is 2 or more,
^f may be the same or different. Examples of the bisphenols represented by the formula [II] include resorcin, 3-methylresorcin, 3-ethylresorcin, 3-propylresorcin, 3-butylresorcin, 3-t-butylresorcin, and 3-phenyl Resorcinol,
Substituted resorcinols such as 3-cumylresorcin, 2,3,4,6-tetrafluororesorcin, 2,3,4,6-tetrabromoresorcin, catechol, hydroquinone and 3-methylhydroquinone, 3-ethylhydroquinone, 3- Propylhydroquinone, 3-butylhydroquinone, 3-t-butylhydroquinone, 3-phenylhydroquinone, 3-cumylhydroquinone, 2,3,5,6-tetramethylhydroquinone, 2,
Substituted hydroquinones such as 3,5,6-tetra-t-butylhydroquinone, 2,3,5,6-tetrafluorohydroquinone, and 2,3,5,6-tetrabromohydroquinone can be mentioned.

The bisphenols further include 2,2,2 ', 2'-tetrahydro-3,3,3', 3'-tetramethyl-1,1'-spirobi- [IH-indene represented by the following formula: ] -6,6'-diol can also be used.

[0025]

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Of these, bisphenols represented by the above formula [I] are preferred, and bisphenol A is particularly preferred.
Is preferred. In the present invention, these two or three types are used.
It is also possible to produce copolymerized polycarbonates by combining two or more kinds of dihydroxy compounds.

The diester carbonate used in the present invention includes diphenyl carbonate, bis (2,4-dichlorophenyl) carbonate, bis (2,4,6-trichlorophenyl) carbonate and bis (2-cyanophenyl) carbonate , Bis (o-nitrophenyl) carbonate, ditolyl carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate, diethyl carbonate, dimethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate and the like. Of these, diphenyl carbonate is preferably used. Two or more of these can be used in combination. Among these, diphenyl carbonate is particularly preferably used.

The carbonic acid diester used in the present invention may contain a dicarboxylic acid or a dicarboxylic acid ester. Specifically, the carbonic acid diester is preferably a dicarboxylic acid or a dicarboxylic acid ester.
It may be contained in an amount of 0 mol% or less, more preferably 30 mol% or less.

As such dicarboxylic acids or dicarboxylic esters, terephthalic acid, isophthalic acid,
Sebacic acid, decandioic acid, dodecandioic acid, diphenyl sebacate, diphenyl terephthalate, diphenyl isophthalate, diphenyl decandioate, diphenyl dodecandioate, and the like can be given. The carbonic acid diester may contain two or more of these dicarboxylic acids or dicarboxylic acid esters.

Polyester polycarbonate is obtained by polycondensing the dicarboxylic acid or diester carbonate containing dicarboxylic acid ester with the aromatic dihydroxy compound.

In the present invention, when producing a polycarbonate, the above-mentioned carbonic acid diester is used in an amount of 0.95 to 1.30 with respect to 1 mol of the total amount of the aromatic dihydroxy compound.
It is desirable to use it in an amount of preferably from 1.01 to 1.20 mol.

In the production method according to the present invention, the copolymerized polycarbonate is prepared by using a polyfunctional compound having three or more functional groups in one molecule together with the aromatic dihydroxy compound and the carbonic acid diester. It can also be manufactured.

As such a polyfunctional compound, a compound having a phenolic hydroxyl group or a carboxyl group is preferable, and a compound having three phenolic hydroxyl groups is particularly preferably used. Specifically, for example, 1,1,1-tris (4-hydroxyphenyl) ethane, 2,2 ′, 2 ″ -tris
(4-hydroxyphenyl) diisopropylbenzene, α-
Methyl-α, α ', α'-tris (4-hydroxyphenyl) -1,4
-Diethylbenzene, α, α ', α "-tris (4-hydroxyphenyl) -1,3,5-triisopropylbenzene, phloroglysin, 4,6-dimethyl-2,4,6-tri (4-hydroxyphenyl ) -Heptane-2,1,3,5-tri (4-hydroxyphenyl)
Benzene, 2,2-bis- [4,4- (4,4'-dihydroxyphenyl) -cyclohexyl] -propane, trimellitic acid, 1,3,
5-benzenetricarboxylic acid, pyromellitic acid and the like.

Of these, 1,1,1-tris (4-hydroxyphenyl) ethane, α, α ′, α ″ -tris (4-hydroxyphenyl) -1,3,5-triisopropylbenzene and the like are preferred. Used.

When these polyfunctional compounds are used, the polyfunctional compound is usually used in an amount of usually not more than 0.03 mol, preferably 0.001 mol, per mol of the aromatic dihydroxy compound.
To 0.02 mol, more preferably 0.001 to 0.01 mol.

In the present invention, the amount of (a) the alkali metal compound and the alkaline earth metal compound contained in the dihydroxy compound and the carbonic acid diester as described above is not more than 1 × 10 ^{-7 based on} 1 mol of the dihydroxy compound. It is preferred that

Such a raw material having an extremely small amount of impurities is obtained by purifying a dihydroxy compound and a carbonic acid diester by a method such as distillation or recrystallization using a production apparatus which is precisely controlled against contamination. And the above-mentioned alkali metal compound or alkaline earth metal compound.

In the present invention, when producing a polycarbonate, an end-capping agent may be used together with the aromatic dihydroxy compound and the carbonic acid diester as described above.
As such a terminal blocking agent, an allyloxy compound capable of introducing a terminal group represented by the following general formula [I] into a molecular terminal of the obtained polycarbonate is used.

ArO -... [I] In the formula, Ar represents an aromatic hydrocarbon group having 6 to 50 carbon atoms. The aromatic hydrocarbon group is not particularly limited, and may be a condensed ring such as a phenyl group, a naphthyl group, and an anthranyl group.
Alternatively, a ring may be formed with a hetero atom. Further, these aromatic rings may be substituted with halogen or an alkyl group having 1 to 9 carbon atoms.

As such allyloxy compounds, specifically, phenol, diphenyl carbonate, p-tert
-Butylphenol, p-tert-butylphenylphenyl carbonate, p-tert-butylphenyl carbonate, p-
Cumylphenol, p-cumylphenylphenyl carbonate, p-cumylphenyl carbonate, 2,2,4-trimethyl-4- (4-hydroxyphenyl) chroman, 2,2,4,6-tetramethyl-4- (3,5-dimethyl-4-hydroxyphenyl) chroman, 2,2,3-trimethyl-3- (4-hydroxyphenyl) chroman, 2,2,3,6-tetramethyl-3- (3,5- Dimethyl-4-hydroxyphenyl) chroman, 2,4,4-trimethyl-2- (2
Chroman compounds such as -hydroxyphenyl) chroman and 2,4,4,6-tetramethyl-2- (3,5-dimethyl-2-hydroxyphenyl) chroman.

The above allyloxy compounds can be used alone or in combination. Such an allyloxy compound is usually used in an amount of 0.01 to 0.2 with respect to 1 mole of the aromatic dihydroxy compound.
Mole, preferably 0.02 to 0.15 mole, more preferably 0.02 to 0.1 mole.

By using an alloxy compound in such an amount as a terminal blocking agent, the molecular terminals of the obtained polycarbonate are 1 to 95%, preferably 10 to 95%.
%, More preferably 20 to 90%, with the terminal group represented by the above general formula [I].

As described above, the polycarbonate having the terminal group represented by the general formula [I] introduced in the above ratio has excellent heat resistance and excellent mechanical properties such as impact resistance even at a low molecular weight.

In the present invention, an aliphatic monocarboxy compound into which an aliphatic hydrocarbon unit represented by the following general formula [XII] can be introduced, if necessary, together with the above-mentioned allyloxy compound is used as a terminal blocking agent. You may.

[0045]

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In the formula, R is alkyl having 10 to 30 carbon atoms, which may be linear or branched;
Further, it may be substituted by halogen. Specific examples of such an aliphatic monocarboxy compound include undecanoic acid, lauric acid, tridecanoic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, nonadecanoic acid, heneicosanoic acid, tricosanoic acid, and mericic acid. And alkyl monocarboxylic acid esters such as methyl ester, ethyl ester and phenyl ester of the above-mentioned alkyl monocarboxylic acids such as methyl stearate, methyl stearate, ethyl stearate and phenyl stearate.

These may be used alone or in combination. The aliphatic monocarboxy compound as described above is usually an aromatic dihydroxy compound 1
It is desirable to use the compound in an amount of 0.01 to 0.20 mol, preferably 0.02 to 0.15 mol, and more preferably 0.02 to 0.10 mol, per mol.

When the above terminal blocking agent is used in an amount of 0.2 mol or more per 1 mol of the aromatic dihydroxy compound, the polymerization rate may be reduced. Polycondensation Step Next, a method for producing a polycarbonate according to the present invention will be described with reference to FIG.

[First-stage polycondensation step] In the present invention, first, the above-mentioned raw materials containing a dihydroxy compound and a carbonic acid diester are mixed in a stirring tank or the like, and then transferred to a polymerization tank for polycondensation. .

In the first stage polycondensation step, (a)
At least one compound selected from ammonium compounds and phosphonium compounds is used. As the compound selected from the group consisting of ammonium compounds and phosphonium compounds, at least one compound selected from the group consisting of quaternary ammonium compounds and quaternary phosphonium compounds is particularly preferred.

Specifically, quaternary such as tetramethylammonium hydroxide (Me ₄ NOH), tetraethylammonium hydroxide (Et ₄ NOH), tetrabutylammonium hydroxide (Bu ₄ NOH) and trimethylbenzylammonium hydroxide Examples include quaternary phosphonium compounds such as ammonium compounds, tetramethylphosphonium hydroxide (Me ₄ POH), tetraethyl phosphonium hydroxide (Et ₄ POH), and tetrabutyl phosphonium hydroxide (Bu ₄ POH).

These compounds can be used alone or in combination of two or more. Such an (a) ammonium compound and phosphonium compound are used in an amount of 1 × 10 ⁻⁷ to 1 × 10 ⁻¹ mol, preferably 1 × 10 ⁻⁵ to 1 × 10 ⁻² mol, per 1 mol of the dihydroxy compound. It is preferable to use them.

The mixing of the polycondensation raw material and the catalyst is usually desirably performed under a nitrogen atmosphere at atmospheric pressure. The first-stage polycondensation reaction is performed at 270 ° C. or lower, preferably 80 to 250 ° C., more preferably 100 to 230 ° C., and still more preferably 12 to 230 ° C.
It is preferably performed at a temperature of 0 to 190 ° C. The reaction time at this time is preferably 0 to 5 hours, preferably 0 to 4 hours, and more preferably 0 to 3 hours.

The pressure at this time is (atmospheric pressure) to 100 torr.
And a nitrogen atmosphere is desirable. [Polycondensation Step of Second and Subsequent Steps] Next, (b) an alkali metal-containing inorganic salt and / or an alkaline earth metal-containing catalyst are added to the polycondensate obtained in the first-stage reaction as a catalyst. A phosphorus inorganic salt is added, and polycondensation is further performed.

Here, the alkali metal phosphorus-containing inorganic salt and / or the alkaline earth metal phosphorus-containing inorganic salt refer to a salt of an alkali metal and / or an alkaline earth metal with a phosphorus-containing inorganic acid. Include lithium, sodium, potassium, cesium, rubidium and the like; alkaline earth metals include magnesium, calcium, strontium and the like; and phosphorus-containing inorganic acids include phosphorous acid, phosphoric acid, hypophosphorous acid Acids, pyrophosphoric acid, triphosphoric acid, polyphosphoric acid and the like can be mentioned.

As (b) the alkali metal phosphorus-containing inorganic salt and / or the alkaline earth metal phosphorus-containing inorganic salt, an alkali metal phosphite is particularly preferable. Specifically, dihydrogen phosphite is used. Lithium (LiH ₂ PO ₃ ), sodium dihydrogen phosphite (NaH ₂ PO ₃ ), potassium dihydrogen phosphite (KH
₂ PO ₃ ), rubidium dihydrogen phosphite (RbH ₂ PO ₃ ), cesium dihydrogen phosphite (CsH ₂ PO ₃ ), dilithium hydrogen phosphite (Li
₂ HPO ₃ ), disodium hydrogen phosphite (Na ₂ HPO ₃ ), dipotassium hydrogen phosphite (K ₂ HPO ₃ ), dirubidium hydrogen phosphite
(Rb ₂ HPO ₃ ), dicesium hydrogen phosphite (Cs ₂ HPO ₃ ), trilithium phosphite (Li ₃ PO ₃ ), trisodium phosphite (Na ₃ P
O ₃ ), tri-potassium phosphite (K ₃ PO ₃ ), tri-rubidium phosphite (Rb ₃ PO ₃ ), and tri-cesium phosphite (Cs ₃ PO ₃ ). Among them, lithium dihydrogen phosphite (LiH ₂ PO ₃ ), sodium dihydrogen phosphite (NaH ₂ PO ₃ ), and potassium dihydrogen phosphite (KH ₂ PO ₃ ) are more preferable.

These compounds may be used alone or in combination of two or more. Such (b) alkali metal phosphorus-containing inorganic salts and / or alkaline earth metal phosphorus-containing inorganic salts include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, and lithium hydrogen carbonate. ,Calcium hydroxide,
Supply alkali metal and / or alkaline earth metal compounds such as barium hydroxide, magnesium hydroxide, and strontium hydroxide, and phosphorus-containing inorganic acids such as phosphorous acid and phosphoric acid to the melt polycondensation vessel through separate routes Then, an alkali metal and / or alkaline earth metal compound may be reacted with the phosphorus-containing inorganic acid in a melt polycondensation vessel to produce the compound.

Such an inorganic salt (b) of an alkali metal phosphorus-containing inorganic salt and / or an alkaline earth metal phosphorus-containing inorganic salt has excellent catalytic activity, but is 1 × 10 ⁻⁷ to 1 mol of a dihydroxy compound. 1 × 10 ^-6 mol, preferably 5 × 1
Desirably, it is used in an amount of 0 ^-7 to 1 × 10 ^-6 mol.

The salt comprising (b) the alkali metal phosphorus-containing inorganic salt and / or the alkaline earth metal phosphorus-containing inorganic salt may be added in its entirety in the second stage. May be added separately so that the total amount is within the above range.

In the second and subsequent polycondensation steps, the reaction temperature is increased while reducing the pressure compared to the first polycondensation step, and the reaction between the bisphenols and the carbonic acid diester is carried out. It is desirable to carry out the polycondensation reaction between bisphenols and carbonic acid diester at 240 to 320 ° C., preferably under a reduced pressure of 1 mmHg or less.

The manufacturing method according to the present invention is not limited to the method shown in FIG.
It may be a batch type. The reaction apparatus used for performing the above reaction may be a tank type, a tube type, or a tower type. Furthermore, the number of polymerization stages may be two or more, and the number of stages is not particularly limited.

The thus obtained polycarbonate of 20
The intrinsic viscosity measured in methylene chloride at 0.1 ° C. is usually 0.10
~ 1.0 dl / g, preferably 0.30-0.65 dl / g. Used as a catalyst in the first stage polycondensation step (a)
A compound selected from an ammonium compound and a phosphonium compound volatilizes under polycondensation conditions under heating under reduced pressure in the second and subsequent stages. Therefore, in the second and subsequent polycondensation steps, when (b) an alkali metal phosphorus-containing inorganic salt and / or an alkaline earth metal phosphorus-containing inorganic salt is used as a polycondensation catalyst, the polymerization can be further continued.

In addition, (a) a compound selected from an ammonium compound and a phosphonium compound which is used as a catalyst in the first polycondensation step, and a compound which is used as a catalyst in the second and subsequent polycondensation steps (b ) When mixed with an alkali metal phosphorus-containing inorganic salt and / or an alkaline earth metal phosphorus-containing inorganic salt, the two may react to form an alkali metal and / or alkaline earth metal hydroxide,
By using (a) a compound selected from an ammonium compound and a phosphonium compound and (b) a salt comprising an alkali metal and / or an alkaline earth metal and a phosphorus-containing inorganic acid in different polycondensation stages as in the present invention. , No alkali metal and / or alkaline earth metal hydroxide is formed, and therefore the following side reactions due to the presence of such a hydroxide are further suppressed, and the general formula (i) It is possible to efficiently produce a polycarbonate having an improved hue with less generation of the branched structure shown in (ii).

[0064]

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According to the production method of the present invention described above, a polycarbonate having excellent hue (hereinafter, polycarbonate [A]) can be obtained with high polymerization activity. Then
In the polycarbonate produced by the method according to the present invention,
The branched structure represented by the general formula (i) is 1000 ppm or less,
More preferably, the amount is preferably 500 ppm or less, and the branched structure represented by (ii) is 100 ppm or less,
More preferably, the amount is desirably 50 ppm or less.

The amount of such a branched structure can be determined by adding an alkali such as sodium hydroxide to the obtained polycarbonate and hydrolyzing it to obtain the following general formulas (i ′) and (i ′).
It can be carried out by generating a branched compound represented by i ′) and measuring the amount of the compound by high performance liquid chromatography (HPLC).

[0067]

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In the present invention, the reaction product [A] polycarbonate obtained as described above is immediately cooled after the polycondensation reaction without cooling, and the following [B] pKa
A sulfur-containing acidic compound having a value of 3 or less and / or a derivative formed from the acidic compound (hereinafter, also referred to as [B] an acidic compound) may be added.

[B] The sulfur-containing acidic compound and the derivative formed from the acidic compound include sulfurous acid, sulfuric acid,
Examples include sulfinic acid compounds, sulfonic acid compounds and derivatives thereof, and specifically, ethyl benzenesulfonate, butyl benzenesulfonate, methyl p-toluenesulfonate, ethyl p-toluenesulfonate, p-toluenesulfonic acid Butyl and the like.

The acidic compound [B] is used in an amount of 0.1 to 50 times, preferably 0.1 to 15 times, the molar amount of the alkali metal phosphite used in the reaction of the above [A] polycarbonate. Desirably, it is contained in a molar amount of 0.1 to 7 times. By adding the acidic compound [B] to the reaction product (polycarbonate) [A] in such an amount, the alkali metal phosphite remaining in the polycarbonate is neutralized or weakened, Finally, a polycarbonate having further improved retention stability and water resistance can be obtained.

[C] water may be added together with the acidic compound [B], and the amount of the water [C] added is 5 to 1000 ppm, preferably 10 to 500 ppm, more preferably 10 to 500 ppm based on the polycarbonate [A]. Is 20-300pp
m is sufficient. When [C] water is added together with the [B] acidic compound, the neutralization efficiency of the polycondensation catalyst in the [A] polycarbonate is further increased, the retention stability during melting is excellent, and the hue, transparency, and water resistance are improved. And a polycarbonate excellent in weather resistance can be obtained.

[A] The polycarbonate is molded by a usual kneader such as a single-screw extruder, a twin-screw extruder, or a static mixer, and these kneaders can be used effectively with or without a vent.

Further, while the [A] polycarbonate obtained by the polycondensation reaction is in a molten state in a reactor or an extruder, [B] an acidic compound and [C] water may be added. The acidic compound [B] and the water [C] may be added separately or simultaneously. The order of addition is not limited, but it is desirable to add them simultaneously.

Further, as long as the object of the present invention is not impaired,
[D] additives may be added to the polycarbonate [A]. [D] Specific examples of the additive include a wide range of additives generally added to polycarbonate depending on the purpose of use, such as heat stabilizers, epoxy compounds, ultraviolet absorbers, release agents, and coloring agents. Agents, antistatic agents, slip agents, antiblocking agents, lubricants, antifogging agents, natural oils, synthetic oils, waxes, organic fillers, inorganic fillers and the like.

The polycarbonate thus produced is pelletized as necessary and used for various applications. The polycarbonate obtained by the production method according to the present invention has excellent hue and is suitable as an optical material.

[0076]

According to the method for producing a polycarbonate according to the present invention, it is possible to suppress the side reaction and efficiently produce a polycarbonate having an improved hue with few branches.

The polycarbonate produced by the method of the present invention can be used not only as a general molding material but also as a building material such as a sheet, an optical lens such as an automobile headlamp lens, eyeglasses, and an optical recording material. It is suitably used, and particularly suitable as a molding material for optical disks.

[0078]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

The physical properties shown in the examples of the present invention are measured as follows. [Quantitative Determination of Alkali Metals and Alkaline Earth Metals in Raw Materials] Raw materials were sampled in clean bottles, and each component was quantitatively analyzed to the ppb level by a normal atomic absorption method. [Hue of Polycarbonate (Yellowness: YI)] A polycarbonate injection molded plate having a thickness of 3 mm was placed at a cylinder temperature of 290.
C., injection pressure 1000 Kg / cm, molding for 45 seconds per cycle, mold temperature 100 ° C., and measuring X, Y and Z values of Color and Color Defference Meter ND-1001 manufactured by Nippon Denshoku Industries Co., Ltd.
The yellowness [YI] was measured by a transmission method using DP.

YI = 100 (1.277X-1.060Z) / Y [Terminal OH group concentration of polycarbonate] Sample 0.4
was dissolved g of chloroform 3ml, ¹³ C-NMR
Ratio of the terminal OH group to the total terminal concentration (%)
Was calculated. [Measurement of polycarbonate branch] The following formulas (1) and (2)
In order to determine the amount of branching represented by, the following two compounds were quantified by high performance liquid chromatography (HPLC) after alkali hydrolysis of polycarbonate.

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Example 1 A polycarbonate polymerization apparatus equipped with one stirring tank for mixing raw materials, two prepolymerization tanks, and two horizontal polymerization tanks was used. The respective reaction conditions are as follows.

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[Table 1]

From the bisphenol A production apparatus, bisphenol A in a molten state directly fed through a pipe (supply rate: 36.0 kg / hr), and diphenyl carbonate in a molten state directly fed through a pipe after distillation (supply rate: 36.0 kg / hr) Feeding speed 3
4.7 kg / hr), a predetermined amount of a phenol solution of the catalyst was continuously supplied to the stirring tank maintained at the above temperature, and the prepolymerization tank I was fed at a supply rate of 36.0 kg / hr in terms of bisphenol A.
The mixture was sequentially supplied to the prepolymerization tank II, the horizontal polymerization tank I, and the horizontal polymerization tank II, and was polymerized under the above reaction conditions to produce a polycarbonate.

The intrinsic viscosity, terminal OH group concentration, polycarbonate hue, and polycarbonate branch of the obtained polycarbonate were quantified. Table 2 shows the results. It was confirmed that the total of the alkali metal compound and the alkaline earth metal compound in the raw material bisphenol A and diphenyl carbonate was 1 × 10 ⁻⁷ mol or less per 1 mol of the dihydroxy compound.

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Examples 2 to 4 and Comparative Examples 1 to 4 In Example 1, except that the type and amount of the catalyst used were as shown in Table 1,
A polycarbonate was produced in the same manner as in Example 1.

Table 2 shows the results.

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[Table 2]

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Takato Kimura, Inventor Chichikachi, Ichihara-shi, Chiba 3rd Japan Chi-Plastics Co., Ltd. (72) Inventor Patrick Jay. Macroski USA River Road, Schenectady, NY 1 General Electric Company Central Research Laboratory (72) Inventor Root Van Haat Netherlands Bergen Optoum AC 4600 General Electric Plastic Baffle F term (reference) 4J029 AA09 AB04 AC01 AD10 AE04 AE05 BB04A BB05A BB06A BB11A BB12A BB13A BD10 BF14A BG05X BG08X BH02 DB07 DB11 DB13 HC04A HC05A HC05B JA261 JC091 JC631 JF021 JF031 JF041 JF051 JF131 JF05 KD01 KB03 KB01

Claims (5)

[Claims] When a polycarbonate is produced by a transesterification reaction using a dihydroxy compound and a carbonic acid diester as raw materials, a transesterification reaction is carried out in a multistage polycondensation step of two or more stages, and in the first polycondensation step, (a) at least one compound selected from an ammonium compound and a phosphonium compound is used as a catalyst, and in the second and subsequent polycondensation steps, (b) an alkali metal-containing phosphorus-containing inorganic salt and / or an alkaline earth metal-containing phosphorus A method for producing a polycarbonate, comprising using an inorganic salt as a catalyst. 2. The method according to claim 1, wherein the first polycondensation step is performed at a temperature of 270 ° C. or lower. Wherein the dihydroxy compound per 1 mole of at least one compound 1 × selected from (a) ammonium compounds and phosphonium compounds 10 ^-7 to 1 × 1
0 ^-1 used in an amount of moles, (b) an alkali metal phosphorous inorganic salts and / or 1 × 10 ^-7 ~1 × a salt comprising an alkaline earth metal-containing phosphorus inorganic salts
3. The method according to claim 1, wherein the polycarbonate is used in an amount of 10 ^-6 mol. 4. The amount of the alkali metal compound and / or alkali metal earth compound contained as impurities in the raw material is not more than 1 × 10 ^-7 mol per 1 mol of the dihydroxy compound. The method for producing a polycarbonate according to claim 1. (5) at least one compound selected from the group consisting of (a) an ammonium compound and a phosphonium compound,
The method for producing a polycarbonate according to any one of claims 1 to 4, wherein the method is at least one compound selected from the group consisting of a quaternary ammonium compound and a quaternary phosphonium compound.