JP2003286337A - Storage tank for aromatic dihydroxy compound and method for producing aromatic polycarbonate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for efficiently producing an aromatic polycarbonate having excellent color and a reduced amount of gels and foreign substances. <P>SOLUTION: In the method for producing an aromatic polycarbonate by melt polycondensation of an aromatic dihydroxy compound with a carbonic diester, in order to store the particulate or bulk aromatic dihydroxy compound to be used as the raw material, a storage tank filled with a gas having an oxygen concentration of 0.0001-1 vol.% is used. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an aromatic polycarbonate. More specifically, it relates to a method for producing an aromatic polycarbonate by a melt polymerization method, and more particularly to a method for efficiently producing an aromatic polycarbonate with less coloring, gel and foreign matter.

[0002]

2. Description of the Related Art Aromatic polycarbonate has impact resistance,
Since it has excellent properties such as transparency, it is widely known as a very useful resin.

As a method for producing an aromatic polycarbonate, an interfacial polycondensation method in which an aromatic dihydroxy compound and phosgene are reacted in a mixed liquid of an organic solvent and an alkaline aqueous solution, and an aromatic dihydroxy compound and a carbonic acid diester are prepared. There is a melt polycondensation method of reacting in the presence or absence of a catalyst under a high temperature and reduced pressure to remove the generated phenol out of the system.

Since the melt polycondensation method has a higher reaction temperature than the interfacial polycondensation method, the main reaction is inhibited by the presence of a slight amount of impurities or oxidizing substances in the raw material, and / or a side reaction is caused. As a result of being promoted, there is a problem that the product is colored and a gel is formed, and it has been studied to remove this factor from the past, but it has not been solved yet.

[0005]

In order to remove impurities and the like which cause coloring and gels and foreign substances in the past, in order to remove insoluble impurities contained in the carbonic acid diester or aromatic dihydroxy compound as a raw material, any desired Filters having shapes and openings have been commonly used.

However, it is difficult to completely remove the insoluble impurities in the raw material even if the impurities are removed by a filter, and the soluble impurities cannot be removed.
It cannot be said that the production of a polycarbonate having an excellent hue by the melt polymerization method has been sufficiently achieved.

On the other hand, coloring of products leads to deterioration of transparency, which is an excellent feature of aromatic polycarbonate, and is a fatal problem particularly when used for optical applications such as compact discs and digital video discs. is there.

Therefore, a technique for improving the hue and quality of the aromatic polycarbonate obtained by the transesterification method has been earnestly desired.

An object of the present invention is to provide a technique capable of improving hue and reducing foreign matters.

Still another object and advantage of the present invention are:
It will be apparent from the following description.

[0011]

As a result of intensive studies to solve the above problems, oxygen contained in a solid aromatic dihydroxy compound, which is one of the raw materials, is a side reaction during the polymerization reaction. It has been found that when a mixed melt of an aromatic dihydroxy compound and a carbonic acid diester is held for a long time, cyclic and / or branched oligomers are generated, which causes coloring of the product and gel or foreign matter, The present invention has been completed.

That is, according to one aspect of the present invention, a particulate or lumpy aromatic dihydroxy compound used as a raw material when an aromatic polycarbonate is produced by melt polycondensation of an aromatic dihydroxy compound and a carbonic acid diester is stored. A storage tank with an oxygen concentration of 0.0001-1
It is a storage tank filled with volume% gas.

The use of such a storage tank makes it possible to improve the hue of the aromatic polycarbonate produced and reduce foreign matters.

This storage tank has an oxygen concentration of 0.000.
Gas of 1 to 1% by volume or more can be circulated in the storage tank and / or the storage tank can be sealed, and the oxygen concentration is 0.00
Gas of 01 to 1% by volume can flow from a portion between the bottom of the storage tank and 1 m above, and the internal pressure of the storage tank is 0.00
It is preferably from 01 to 0.2 MPa. This is because the contact with oxygen can be surely reduced.

Yet another aspect of the present invention is a method for producing an aromatic polycarbonate characterized by using the above-mentioned storage tank.

In this case, the mixed melt obtained by mixing and melting the aromatic dihydroxy compound and the carbonic acid diester,
It is preferable to perform the melt polycondensation by subjecting it to a polymerization step within 72 hours.

By adopting such a method for producing an aromatic polycarbonate, it is possible to improve the hue of the produced aromatic polycarbonate and reduce foreign matters.

Further features of the present invention will be clarified in the embodiments and examples of the invention described below.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to examples and the like. It should be noted that these examples and the like and the explanations exemplify the present invention, and do not limit the scope of the present invention. It goes without saying that other embodiments may belong to the scope of the present invention as long as they match the gist of the present invention.

The aromatic polycarbonate referred to in the present invention comprises an aromatic dihydroxy compound and a carbonic acid diester, which are the main components, in the absence of a catalyst or a nitrogen-containing basic compound and an alkali metal compound and / or an alkaline earth metal. It is an aromatic polycarbonate melt-polycondensed in the presence of a transesterification catalyst comprising a compound.

The aromatic dihydroxy compound is in a solid state and comprises bis (4-hydroxyphenyl) methane,
2,2-bis (4-hydroxyphenyl) propane,
2,2-bis (4-hydroxy-3-methylphenyl)
Propane, 4,4-bis (4-hydroxyphenyl) heptane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3,5-dibromophenyl) Propane, bis (4-
Hydroxyphenyl) oxide, bis (3,5-dichloro-4-hydroxyphenyl) oxide, p, p '
-Dihydroxydiphenyl, 3,3'-dichloro-4,
4'-dihydroxydiphenyl, bis (hydroxyphenyl) sulfone, resorcinol, hydroquinone,
1,4-dihydroxy-2,5-dichlorobenzene,
1,4-dihydroxy-3-methylbenzene, bis (4
-Hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfoxide and the like can be mentioned, but 2,2-bis (4-hydroxyphenyl) propane is particularly preferable.

Examples of carbonic acid diesters include diphenyl carbonate, bis (tolylphenyl) carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate and bis (diphenyl).
Carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate and the like can be mentioned, but diphenyl carbonate is particularly preferable.

The use ratio of the two kinds of raw materials used in the present invention can be appropriately changed depending on the amount of OH end groups of the polycarbonate to be produced, but the number of moles of the carbonic acid diester used is divided by the number of moles of the aromatic dihydroxy compound used. The raw material molar ratio represented by the above value is usually 0.8 to 1.
5, preferably 0.95 to 1.1, more preferably 1.0 to
It is particularly preferable to use it in the range of 1.05.

Further, the aromatic polycarbonate of the present invention may contain ethylene glycol, 1,4-butanedihydroxy, 1,1,4 as an aliphatic dihydroxy compound, if necessary.
4-Cyclohexanedimethanol, 1,10-decanedihydroxy, etc. are used as dicarboxylic acids such as succinic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, cyclohexanecarboxylic acid and terephthalic acid, for example, lactic acid, P- It may contain oxyacids such as hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid.

The aromatic dihydroxy compound according to the present invention is in the form of particles or lumps so that the gas penetrating between the aromatic dihydroxy compounds can be easily replaced with a gas containing less oxygen. There is no particular limitation on its size or specific shape.

However, the present invention may be effective even in the case where it is difficult to replace the gas in the pellet with the external gas, for example, when it is pressed and solidified into pellets. Such pellets also belong to the “lumpy” of the present invention.

The reason why it is effective is that the amount of gas in the pellet becomes very small by pressing and hardening,
It is presumed that the problem can be avoided even when the pellet is compacted under a gas containing little oxygen and the amount of gas in the pellet is not replaced.

The above-mentioned storage tank is effective for obtaining such an aromatic dihydroxy compound.

The gas filling the storage tank preferably has an oxygen concentration of 0.0001 to 1% by volume, more preferably 0.0001 to 0.001% by volume.

When the oxygen concentration exceeds 1% by volume, coloring, gelation and foreign matter are likely to occur. The lower the oxygen concentration, the better, but it is economically disadvantageous to set it to less than 0.0001% by volume, and technical difficulties increase.

Here, whether or not the oxygen concentration is filled with the gas having a predetermined concentration or less is determined by measuring the gas composition in the storage tank. If it is indicated that the oxygen concentration in one part of the storage tank is below the specified concentration,
The conditions of the storage tank according to the present invention can be satisfied.

However, when the composition of the gas in the storage tank is not uniform, the effect of the present invention may be reduced, so
More preferably, it is determined by measuring the gas composition at multiple points in the storage tank.

Which part in the storage tank should be measured, how many parts should be measured, how often, etc. can be determined by trial and error. After such conditions are clarified, it is possible to reduce the measurement location and the measurement frequency. In some cases, one measurement may be sufficient.

When the storage tank has a pipe portion, it may take time to replace the gas remaining in the pipe portion. Therefore, it is necessary to positively introduce a predetermined gas into the pipe portion or reduce the time. It may be useful to analyze the gas composition in the reservoir.

In order to realize a state of the storage tank filled with a gas having an oxygen concentration of a predetermined concentration or lower, it is preferable that a gas having an oxygen concentration of the predetermined concentration or lower be able to flow through the storage tank.

For this flow, it is useful to flow a gas having an oxygen concentration of a predetermined concentration or less from a portion between the bottom of the storage tank and 1 m above.

When the oxygen concentration in the gas containing the aromatic dihydroxy compound is high, in order to reduce this oxygen concentration as quickly as possible, the oxygen concentration should be evenly distributed from the bottom of the granular or lumpy aromatic dihydroxy compound. It is effective to blow a gas having a predetermined concentration or less, but in practice, it has been proved that it is sufficient to circulate the gas from a portion 1 m above the bottom of the storage tank. It is more preferable to flow from a portion between the bottom of the storage tank and 0.5 m above.

From another point of view, it is preferable that the storage tank can be sealed.

This is because oxygen is likely to enter from the outside unless it is sealed.

In a sealed state, it is highly reliable to blow a gas having an oxygen concentration of not more than a predetermined concentration at all times or by monitoring the gas composition and blowing in accordance with the change.

It is preferable that the internal pressure of the storage tank is 0.0001 to 0.2 MPa in addition to the simple sealing.

This is because the invasion of oxygen can be surely prevented.

The aromatic dihydroxy compound is preferably stored in the storage tank under the above conditions for 2 to 24 hours. If it is less than 2 hours, the gas contained in the aromatic dihydroxy compound may not be sufficiently replaced.
This is because if the time exceeds 4 hours, the effects of the present invention often reach the ceiling.

When the aromatic dihydroxy compound is stored using such a storage tank and the aromatic polycarbonate is produced by melt polycondensation using the storage tank, the hue of the aromatic polycarbonate obtained is improved and gel and foreign matters are not generated. Decrease.

In the case of producing an aromatic polycarbonate, in addition to the above, a mixed melt obtained by mixing and melting an aromatic dihydroxy compound and a carbonic acid diester is subjected to a polymerization step within 72 hours to perform melt polycondensation. Preferably. It is more desirable that it is within 48 hours instead of within 72 hours.

If the time required for the polymerization step is too long, cyclic and / or branched oligomers are formed in the molten mixture of the aromatic dihydroxy compound and the carbonic acid diester, which may cause gels and foreign substances in the product. Because,
This is because it is not preferable.

In the gas having a low oxygen concentration used in the present invention, an inert gas is preferable as a component other than oxygen. As the inert gas, so-called noble gases such as argon and neon, as well as nitrogen and carbon dioxide gas, which do not interact with the aromatic dihydroxy compound or carbonic acid diester, can be used. Nitrogen is particularly preferably used.

Whether or not the inert gas is referred to in the present invention is tested, for example, on a beaker scale as an atmosphere gas when an aromatic polycarbonate is produced from an aromatic dihydroxy compound and a carbonic acid diester by melt polycondensation. This can be confirmed by dividing the case where the target gas is used and the case where nitrogen gas is used and comparing the hues of the aromatic polycarbonates produced.

The catalyst used in the present invention is not particularly limited, but a transesterification catalyst composed of a nitrogen-containing basic compound and an alkali metal compound and / or an alkaline earth metal compound can be used.

As the alkali metal and / or alkaline earth metal compound used in the present invention, known compounds can be used without particular limitation as long as they do not reduce the hue of the aromatic polycarbonate obtained.

Examples of the alkali metal compound used as the catalyst include alkali metal hydroxides, hydrogen carbonates, carbonates, acetates, nitrates, nitrites, sulfites, cyanates, thiocyanates and stearates. , Borohydride salts, benzoates, borohydrides, bisphenols, phenol salts and the like, 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 nitrate, potassium nitrate, lithium nitrate, sodium nitrite, potassium nitrite, lithium nitrite, sodium sulfite, potassium sulfite, lithium sulfite, sodium cyanate, potassium cyanate, lithium cyanate, sodium thiocyanate, Potassium thiocyanate, lithium thiocyanate, sodium stearate, potassium stearate, lithium stearate, sodium borohydride, potassium borohydride, lithium borohydride, sodium phenyl borate, sodium benzoate, potassium benzoate,
Examples thereof include lithium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, bisphenol A disodium salt, dipotassium salt, dilithium salt, phenol sodium salt, potassium salt, and lithium salt.

Examples of the alkaline earth metal compound used as a catalyst include hydroxides, hydrogen carbonates, carbonates, acetates, nitrates, nitrites, sulfites, cyanates and thiocyanates of alkaline earth metals. , Stearate,
Benzoate, bisphenol, salts of phenol and the like, calcium hydroxide, barium hydroxide, strontium hydroxide, calcium hydrogen carbonate, barium hydrogen carbonate,
Strontium hydrogen carbonate, calcium carbonate, barium carbonate, strontium carbonate, calcium acetate, barium acetate, strontium acetate, calcium nitrate, barium nitrate, strontium nitrate, calcium nitrite, barium nitrite, strontium nitrite, calcium sulfite, barium sulfite, sulfite Strontium, calcium cyanate, barium cyanate, strontium cyanate, calcium thiocyanate, barium thiocyanate, strontium thiocyanate, calcium stearate, barium stearate, strontium stearate, calcium borohydride, barium borohydride, borohydride Strontium, calcium benzoate, barium benzoate, strontium benzoate, calcium salt of bisphenol A, ba Umushio, strontium salt, calcium salt of phenol, barium salt, etc. strontium salts.

In the present invention, if desired, (a) an alkali metal salt of an ate complex of an element of Group 14 of the periodic table or (b) an oxo acid of an element of Group 14 of the periodic table, as an alkali metal compound of the catalyst. Alkali metal salts of can be used. Here, the elements of Group 14 of the periodic table refer to silicon, germanium, and tin.

(A) Alkali metal salts of ate complexes of Group 14 elements in the periodic table include those described in JP-A-7-268091. Specifically, NaGe (O
Me) ₅ , NaGe (OEt) ₃ , NaGe (OP
r) ₅ , NaGe (OBu) ₅ , NaGe (OPh) ₅ ,
LiGe (OMe) ₅ , LiGe (OBu) ₅ , LiGe
Examples thereof include germanium (Ge) compounds such as (OPh) ₅ .

As a compound of tin (Sn), NaSn
(OMe) ₃ , NaSn (OMe) ₂ (OEt), NaS
_{n (OPr) 3, NaSn (} O-n-C 6 H 13) 3, Na
Sn (OMe) ₅ , NaSn (OEt) ₅ , NaSn (O
_{Bu) 5, NaSn (O-} n-C 12 H 25) 5, NaSn
(OEt), NaSn (OPh) ₅ , NaSnBu ₂ (O
Me) ₃ can be mentioned.

Examples of the alkali metal salt of oxo acid of Group 14 element of the periodic table (b) include silicic acid (sili)
Cic acid alkali metal salt, stannic acid (sta
nic acid) alkali metal salt, germanium (II) acid (germanous acid) alkali metal salt, germanium (IV) acid (germanic)
Acidic alkali metal salts may be mentioned as preferred ones.

The alkali metal salt of silicic acid is, for example, an acidic or neutral alkali metal salt of monosilicic acid or its condensate, such as monosodium orthosilicate, disodium orthosilicate,
Examples include trisodium orthosilicate and tetrasodium orthosilicate.

The alkali metal salt of stannic acid is, for example, an acidic or neutral alkali metal salt of monostannic acid or its condensate, and examples thereof include disodium monostannate (Na ₂ SnO ₃ .x).
H ₂ O, x = 0 to 5), and tetrasodium monostannate (Na ₄ SnO ₄ ) can be mentioned.

Germanium (II) acid (germano)
The alkali metal salt of (us acid) is, for example, an acidic or neutral alkali metal salt of monogermanic acid or a condensate thereof, and examples thereof include monosodium germanate (NaHGeO ₂ ).

Germanium (IV) acid (germani)
The alkali metal salt of c acid) is, for example, an acidic or neutral alkali metal salt of monogermanium (IV) acid or a condensation product thereof, and examples thereof include orthogermanate monolithic acid (LiH ₃ GeO ₄ ) orthogermanate. Disodium salt, orthogermanic acid tetrasodium salt, digermanic acid disodium salt (Na
₂ Ge ₂ O ₅ ), tetragermanic acid disodium salt (Na ₂ Ge ₄ O ₉ ) and pentagermanic acid disodium salt (Na ₂ Ge ₅ O ₁₁ ).

Alkali metal compound or catalyst as a catalyst
The alkaline earth metal compound is an alkali metal element in the catalyst.
Or an alkaline earth metal element is an aromatic dihydroxy compound
1 x 10 per mole of product^-8~ 5 x 10^-FiveBe equivalent
Preferably 5 × 10^-7~ 1 x 10^-FiveSpecially equivalent
Is preferred. Here, the equivalent weight means an alkali contained in one molecule.
The sum of the valences of the remetal element and the alkaline earth metal element
The relationship between the mole and the equivalent is the alkali metal in one molecule.
When one element (monovalent) is contained, 1 mol is equivalent to 1 equivalent.
Equal and contains one alkaline earth metal element (divalent)
1 mole equals 2 equivalents. 1 minute
When the child contains two alkali metal elements (monovalent)
1 mole equals 2 equivalents. Alkali gold in the catalyst
Aromatic dihydrides containing a group of elements or alkaline earth metals
1 x 10 per mol of Roxy compound ^-8~ 5 x 10^-FiveEquivalent
Outside the range, the physical properties of the obtained polycarbonate
May be adversely affected and reverse transesterification reaction may occur.
The problem that high-molecular-weight polycarbonate cannot be obtained
Is not preferred.

As the nitrogen-containing basic compound as a catalyst, for example, tetramethylammonium hydroxide (Me ₄ NOH), tetraethylammonium hydroxide (Et ₄ NOH), tetrabutylammonium hydroxide (Bu ₄ NOH), benzyl can be used. Trimethylammonium hydroxide (φ-CH ₂ (Me) ₃ NOH), hexadecyltrimethylammonium hydroxide, and other ammonium hydroxides having alkyl, aryl, or alkylaryl groups, triethylamine, tributylamine, dimethylbenzylamine, hexadecyl Tertiary amines such as dimethylamine, or tetramethylammonium borohydride (Me ₄ NB
H ₄ ), tetrabutylammonium borohydride (Bu ₄ NBH ₄ ), tetrabutylammonium tetraphenylborate (Me ₄ NBPh ₄ ), tetrabutylammonium tetraphenylborate (Bu ₄ NBPh ₄ ), and other basic salts can be given. it can.

The nitrogen-containing basic compound is a nitrogen-containing basic compound.
The ammonium nitrogen atom in the compound is aromatic dihydroxy
1 x 10 per mole of compound^-Five~ 5 x 10^-3Equivalent rate
It is preferably used in combination. The more preferable ratio is the same standard
For 2 × 10^-Five~ 5 x 10 ^-FourEquivalent, 5 × 10^-Five
~ 5 x 10^-FourAn equivalent amount is particularly preferable.

In the present specification, an alkali metal compound, an alkaline earth metal compound, and a charged aromatic diol compound (also referred to as aromatic dihydroxy compound) are used.
The ratio of the nitrogen-containing basic compound was expressed as "the amount of Z (compound name) equivalent to W (numerical value) as metal or basic nitrogen with respect to 1 mol of the aromatic dihydroxy compound". If there is one sodium atom such as phenoxide or 2,2-bis (4-hydroxyphenyl) propane monosodium salt, or if there is one basic nitrogen such as triethylamine, the amount of Z is W mol. It means that the amount is equivalent, and if it is two such as 2,2-bis (4-hydroxyphenyl) propane disodium salt, it means that the amount is equivalent to W / 2 mol.

In the polycondensation reaction of the present invention, at least one selected from the group consisting of an oxo acid of Group 14 element of the periodic table and an oxide of the same, together with the above catalyst, if necessary.
A co-catalyst of the species can be present together.

By using these co-catalysts in a specific ratio, a branching reaction that easily occurs during the polycondensation reaction without impairing the end-blocking reaction and the polycondensation reaction rate, and a foreign substance in the apparatus during molding processing It is possible to more effectively suppress undesired side reactions such as the formation and burning of the.

In the present invention, the polycarbonate obtained from the polymerization tank by the above method is not colored and shows good quality with a small amount of foreign matter content. However, the catalyst deactivator was continuously added using a vented twin-screw ruder. Treatment and devolatilization treatment can be performed. At this time, the polycarbonate may be directly supplied to the ruder from the polymerization machine in a molten state, or may be once cooled and pelletized and then supplied to the ruder.

As the quenching agent used in the present invention, known quenching agents are effectively used. Among them, ammonium salts of sulfonic acid and phosphonium salts are preferable, and further dodecylbenzenesulfonic acid tetrabutylphosphonium salt and the like. The above salts of dodecylbenzenesulfonic acid and the above salts of paratoluenesulfonic acid such as tetrabutylammonium paratoluenesulfonic acid are preferable. As sulfonic acid esters, methyl benzene sulfonate, ethyl benzene sulfonate, butyl benzene sulfonate, octyl benzene sulfonate, phenyl benzene sulfonate, methyl para-toluene sulfonate, ethyl para-toluene sulfonate, ethyl para-toluene sulfonate, para-toluene sulfonate, para Octyl toluene sulfonate, phenyl paratoluene sulfonate and the like are preferably used, and among them, dodecylbenzene sulfonic acid tetrabutylphosphonium salt is most preferably used.

The amount of these deactivators used is 0.5 to 50 mol, preferably 0.5 to 10 mol, per 1 mol of the polymerization catalyst selected from alkali metal compounds and / or alkaline earth metal compounds. It can be used in a molar ratio of 0.8 to 5 mol.

These deactivators are added or kneaded directly or after being dissolved or dispersed in a suitable solvent to the molten polycarbonate resin.

Further, in the present invention, other additives can be added to the polycarbonate resin within the range not impairing the object of the present invention.

Examples of such additives include processing stabilizers, heat resistance stabilizers, antioxidants, light stabilizers, ultraviolet absorbers, metal deactivators, metal soaps, nucleating agents, antistatic agents. , Slip agents, anti-blocking agents, lubricants, flame retardants, mold release agents, anti-mold agents, colorants, anti-fog agents, natural oils, synthetic oils, waxes, organic fillers, inorganic fillers, epoxy compounds. be able to.

Among these, heat stabilizers, ultraviolet absorbers, release agents, coloring agents and the like are particularly commonly used, and these can be used in combination of two or more kinds.

For the purpose of processing stabilizers, heat resistance stabilizers, antioxidants, etc. used in the present invention, for example, phosphorus compounds, phenolic stabilizers, organic thioether stabilizers,
Examples thereof include hindered amine-based stabilizers.

As the light stabilizer, the ultraviolet absorber, etc., a general ultraviolet absorber is used. For example, salicylic acid type ultraviolet absorber, benzophenone type ultraviolet absorber, benzotriazole type ultraviolet absorber, cyanoacrylate type ultraviolet absorber. Examples thereof include agents.

As the release agent, a generally known release agent can be used. For example, a hydrocarbon-based release agent such as paraffin, a fatty acid-based release agent such as stearic acid, stearic acid amide and the like. The fatty acid amide-based release agent, stearyl alcohol, pentaerythritol, and other alcohol-based release agents, glycerin monostearate and other fatty acid ester-based release agents, silicone oil and other silicone-based release agents, and the like.

As the colorant, organic or inorganic pigments or dyes can be used.

Examples of the metal deactivator include N, N '.
-[3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and the like, and examples of the metal soap include calcium stearate, nickel stearate and the like.

Examples of the antistatic agent include quaternary ammonium salt compounds such as (β-lauramidopropyl) trimethylammonium methyl sulfate and alkyl phosphate compounds.

Examples of the nucleating agent include sorbitol compounds such as sodium di (4-t-butylphenyl) phosphonate, dibenzylidene sorbitol, and methylenebis (2,4-di-t-butylphenol) acid phosphate sodium salt, and phosphoric acid. Examples thereof include salt compounds.

Examples of the lubricant include erucic acid amide and stearic acid monoglyceride, and examples of the flame retardant include halogen-containing phosphates such as tris (2-chloroethyl) phosphate, hexabromocyclododecane, decabromophenyl oxide and the like. And the like, metal inorganic compounds such as antimony trioxide, antimony trioxide, antimony pentoxide, and aluminum hydroxide, and mixtures thereof.

These additives are added to the polycarbonate in a molten state and kneaded directly, or after being dissolved or dispersed in a suitable solvent or polymer, or as master pellets. There is no particular limitation on the equipment used to carry out such an operation, but for example, a twin-screw extruder or the like is preferable, and when supplying the additive in the form of a solution, a metering pump such as a plunger pump is used, When the additive is supplied in the form of a master polymer, a side feeder or the like is generally used. When the additive is dissolved or dispersed in a solvent, a vented twin-screw extruder is particularly preferably used.

The polycarbonate obtained in the present invention is
After adding the additives as described above, it is also possible to filter with a polymer filter according to a known method. In this case, the effect of extending the life of the polymer filter as compared with the conventional one can be obtained by reflecting the low content of foreign matter.

[0084]

EXAMPLES Examples will be described below. Unless otherwise specified,% and parts in the examples are% by weight or parts by weight. The physical properties of the polycarbonate obtained in the following examples were measured as follows.

(Intrinsic viscosity and viscosity average molecular weight) 0.7
The intrinsic viscosity of a g / dL methylene chloride solution was measured using an Ubbelohde viscometer, and the viscosity average molecular weight was determined by the following formula.

[Η] = 1.23 × 10 ⁻⁴ M ^0.83 (color tone (b value)) of polycarbonate pellets (minor diameter × long diameter × length (mm) = 2.5 × 3.3 × 3.0) Lab
The value was measured by the reflection method using ND-1001DP manufactured by Nippon Denshoku Industries Co., Ltd., and the b value was used as a measure of yellowness.

(Foreign matter) Polycarbonate pellet 1 kg
Then, the solution dissolved in 10 L of methylene chloride was passed through a liquid particle counter (manufactured by Hiac / Royco) by a light scattering / light blocking method using laser light, and the number of foreign matters contained in the pellet was counted. It was

(Gel) Polycarbonate pellets 1k
A solution obtained by taking g and dissolving it in 10 L of methylene chloride was filtered with a filter having an opening of 30 μm, and the filter was observed under a microscope while irradiating with black light in a dark room to count the number of fluorescent portions.

Example 1 A closed storage tank as shown in FIG. 1 in which nitrogen having a purity of 99.99% by volume was circulated (internal pressure was maintained at 0.003 MPa by appropriately evacuating, oxygen concentration was 0.01% by volume). ) Holds prill-like bisphenol A having an average particle size of 1 mm as an aromatic dihydroxy compound, and this and diphenyl carbonate in a molten state distilled and purified as a carbonic acid diester in a molar ratio of diphenyl carbonate / bisphenol A = 1. It was supplied to a raw material preparation tank having a steam jacket and a steam coil so as to have 0.01, and mixed and melted while stirring.

Then, the entire amount was transferred to the raw material supply tank and continuous polymerization was carried out.

The average residence time in the raw material supply tank was 16 hours, and the polymer was passed through a filter, filtered, and then continuously supplied together with the catalyst solution to the initial polymerization tank having a stirrer, a jacket and a coil. Then, continuous melt polycondensation was carried out.

As the polymerization catalyst, a disodium salt of bisphenol A and tetramethylammonium hydroxide were used, and phenol / water = 90 / in a catalyst preparation tank.
After dissolving in a 10 wt% mixture, bisphenol A1
1 x 1 disodium salt of bisphenol A per mole
0 ^-6 equivalents, tetramethylammonium hydroxide 1
It was supplied to the initial polymerization tank so that the ^{concentration} became × 10 ^-4 mol.

The polymerization equipment is composed of an initial polymerization tank and a late polymerization tank. The operating conditions of each polymerization tank are as follows: the initial polymerization tank has an internal temperature of 250 ° C., the degree of vacuum is 4000 Pa, and the latter polymerization tank has an internal temperature of 270. The degree of vacuum and the degree of vacuum were 67 Pa.

The operating time was 600 hours continuously. Polycarbonate samples were taken once at a frequency of once a day at the outlet of the latter polymerization tank and evaluated for quality. The results are shown in Table 1.
This data is the average of three samples.

The composition of the gas in the storage tank, through which nitrogen having the above-mentioned purity of 99.99% by volume was circulated, is a straight body portion having a diameter of 2.0 m and a height of 2.5 m and a cone having a height of 1.7 m at the bottom. The measurement was performed at point A in FIG.

As a result, the gas in the storage tank had an average nitrogen concentration of 99.99% by volume and an oxygen concentration of 0.01% by volume.

The storage tank intermittently received the aromatic dihydroxy compound.

Levels of aromatic dihydroxy compounds are shown in FIG.
It was kept between 2.2 m and 2.45 m from the upper end of the straight body part of the storage tank 1. In addition, nitrogen is introduced into the storage tank outlet 2 of FIG.
It went from 50 cm above.

The average residence time of the aromatic dihydroxy compound in the storage tank was 12 hours.

Example 2 A storage tank similar to that of Example 1 in which nitrogen having a purity of 99.99% by volume was circulated (internal pressure was maintained at 0.001 MPa by appropriately evacuating, oxygen concentration was 0.0
1% by volume) holds a prill-like bisphenol A having an average particle size of 1 mm as an aromatic dihydroxy compound, and this is mixed with diphenyl carbonate in a molten state distilled and purified as a carbonic acid diester in a molar ratio of diphenyl carbonate / bisphenol A. The mixture was supplied to a raw material preparation tank having a steam jacket and a steam coil so that the ratio became 1.01, and mixed and melted while stirring.

Then, the entire amount was transferred to the raw material supply tank, and the molten raw material mixture was continuously supplied from the raw material supply tank to carry out continuous polymerization.

The average residence time in the raw material supply tank was 24 hours, and the polymer was passed through a filter, filtered, and then continuously supplied to the initial polymerization tank having a stirrer, a jacket and a coil together with the catalyst solution. Then, continuous melt polycondensation was carried out.

As a polymerization catalyst, a disodium salt of bisphenol A and tetramethylammonium hydroxide were used, and phenol / water = 90 / in a catalyst preparation tank.
After dissolving in a 10 wt% mixture, bisphenol A1
1 x 1 disodium salt of bisphenol A per mole
0 ^-6 equivalents, tetramethylammonium hydroxide 1
It was supplied to the initial polymerization tank so that the ^{concentration} became × 10 ^-4 mol.

The polymerization equipment is composed of an initial polymerization tank and a late polymerization tank. The operating conditions of each polymerization tank are as follows: the initial polymerization tank has an inner temperature of 250 ° C., the degree of vacuum is 4000 Pa, and the latter polymerization tank has an inner temperature of 270. The degree of vacuum and the degree of vacuum were 67 Pa.

The operating time was 530 hours continuously. Polycarbonate samples were taken once at a frequency of once a day at the outlet of the latter polymerization tank and evaluated for quality. The results are shown in Table 1.
This data is the average of three samples.

The composition of the gas in the storage tank in which nitrogen having the above-mentioned purity of 99.99% by volume was circulated was measured in the same manner as in Example 1.

As a result, the gas in the storage tank had an average nitrogen concentration of 99.99% by volume and an oxygen concentration of 0.01% by volume.

The aromatic dihydroxy compound was intermittently received in the storage tank.

Levels of aromatic dihydroxy compounds are shown in FIG.
1.46m and 1.71m from the upper end of the straight body part of the storage tank 1
Was kept between.

The average residence time of the aromatic dihydroxy compound in the storage tank was 24 hours.

[Example 3] Example 1 except that bisphenol A was held as the aromatic dihydroxy compound for 30 minutes.
Continuous operation was carried out for 580 hours under the same equipment and operating conditions.

Polycarbonate samples were sampled at the outlet of the latter polymerization tank at a frequency of once / day and evaluated for quality. The results are shown in Table 1.

Example 4 A raw material mixture was prepared from
The same apparatus as in Example 1 except that the one that has passed the time is used,
Continuous operation was carried out for 500 hours under the same operating conditions.

Polycarbonate samples were sampled at the outlet of the latter polymerization tank at a frequency of once / day and evaluated for quality. The results are shown in Table 1.

[Comparative Example 1] Nitrogen having a purity of 99.99% by volume was circulated, but the same procedure as in Example 1 was carried out except that the flow rate was reduced.

The results of quality evaluation are shown in Table 1. This data is the average of three samples.

As a result, the gas in the storage tank had an average nitrogen concentration of 95% by volume and an oxygen concentration of 5% by volume.

[0118]

[Table 1]

[0119]

EFFECTS OF THE INVENTION According to the present invention, an aromatic polycarbonate having an excellent hue and containing less gel and foreign matter can be efficiently produced.

[Brief description of drawings]

FIG. 1 is a schematic view of an aromatic hydroxy compound storage tank.

[Explanation of symbols]

1 storage tank 2 Storage tank outlet (bottom)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toru Sawaki             2-1, Hinodecho, Iwakuni, Yamaguchi Prefecture Teijin Limited             Company Iwakuni Research Center (72) Inventor Katsushi Sasaki             2-1, Hinodecho, Iwakuni, Yamaguchi Prefecture Teijin Limited             Company Iwakuni Research Center F-term (reference) 4J029 AA09 AB04 AB07 BB04A                       BB05A BB05B BB10A BB12A                       BB13A BB13B BF14A BG05X                       BG07X BG08X BG24X BH02                       DB07 DB13 DB15 HA01 HC04A                       HC05A HC05B KB13 KB22                       KD06 KD09 KD17 KE05 LB01

Claims (6)

[Claims] 1. A storage tank for storing a particulate or lumpy aromatic dihydroxy compound, which is used as a raw material in the production of an aromatic polycarbonate by melt polycondensation of an aromatic dihydroxy compound and a carbonic acid diester, wherein A storage tank filled with a gas having a concentration of 0.0001 to 1% by volume. 2. The storage tank according to claim 1, wherein a gas having an oxygen concentration of 0.0001 to 1% by volume can flow in the storage tank and / or the storage tank can be sealed. 3. The storage tank according to claim 1 or 2, wherein the gas having an oxygen concentration of 0.0001 to 1% by volume can flow from a portion between the bottom of the storage tank and 1 m above. 4. The internal pressure of the storage tank is 0.0001-0.
It is 2 MPa, The storage tank in any one of Claims 1-3 characterized by the above-mentioned. 5. A method for producing an aromatic polycarbonate by melt polycondensation of an aromatic dihydroxy compound and a carbonic acid diester, wherein the storage tank according to any one of claims 1 to 4 is used. Method. 6. The mixed melt obtained by mixing and melting an aromatic dihydroxy compound and a carbonic acid diester is subjected to a polymerization step within 72 hours for melt polycondensation. A method for producing an aromatic polycarbonate.