JP2002069167A - Production method for aromatic polycarbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing, effectively and without lowering a polymerization rate, an aromatic polycarbonate excellent in hue, stability of hue, heat stability and further transparency. SOLUTION: Piping for pneumatically transporting powder of an aromatic dihydroxy compound, is made so as to satisfy R>=5 D (wherein D is inner diameter of pipe and R is radius of curvature), the number of bending parts of pipe of 50 or below and a total length of pipe of 500 m or below, when producing this aromatic polycarbonate by melt-polycondensation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an aromatic polycarbonate. More specifically, regarding a method for producing an aromatic polycarbonate by a melt polymerization method,
The present invention relates to a method for efficiently producing an aromatic polycarbonate having excellent hue, hue stability, and thermal stability and excellent transparency.

[0002]

2. Description of the Related Art Aromatic polycarbonate resins are widely known as very useful resins because of their excellent properties such as impact resistance and transparency.

As a method for producing this aromatic polycarbonate resin, an interface method in which an aromatic dihydroxy compound and phosgene are reacted in a mixture of an organic solvent and an aqueous alkali solution, and an aromatic dihydroxy compound and a carbonic acid diester are used. There is a melt polycondensation method in which a reaction is carried out at high temperature and reduced pressure in the presence of a catalyst to remove phenol generated outside the system.

[0004]

In the melt polycondensation method, an aromatic dihydroxy compound and a carbonic acid diester are used as raw materials.

[0005] When handling carbonic acid diester, it can be used in a molten state at a temperature higher than its melting point,
It can be handled as a powder at a temperature below the melting point.

On the other hand, it has been known that the aromatic dihydroxy compound is easily decomposed and colored due to its low heat resistance when treated in a molten state at a temperature higher than its melting point, so that the hue of the polymer deteriorates. I have.

For this reason, when preparing a monomer mixture in melt polycondensation, generally, a molten carbonic acid diester is weighed, and a powdered aromatic dihydroxy compound is weighed and charged therein, followed by mixing and dissolving. To prepare a monomer mixture.

When handling the aromatic dihydroxy compound of the powder, the transport atmosphere is usually set to nitrogen or the like in order to prevent dust explosion and to prevent the polymer hue from being deteriorated by oxygen present in the powder. It is performed under an atmosphere of an inert gas.

However, even if the aromatic dihydroxy compound in the powder is transported under a sufficient nitrogen atmosphere, the color of the polymer may be deteriorated, and in some cases, the polymerization reaction may not proceed. .

Deterioration of the hue impairs the excellent characteristics of the aromatic polycarbonate such as transparency, and is not preferable in terms of product quality particularly when used for optical applications such as compact discs.

Further, the fact that the polymerization reaction does not proceed has a fatal result that an aromatic polycarbonate cannot be produced by melt polycondensation.

[0012]

Means for Solving the Problems The present invention is as follows.

1. In producing an aromatic polycarbonate by melt-polycondensing a carbonic acid diester and an aromatic dihydroxy compound in the presence of a catalyst, the pipe inner diameter at each bent portion of the pipe for pneumatically transporting the powdered aromatic dihydroxy compound Is D (m) and the radius of curvature is R
When (m) is satisfied, the following formula (1) R ≧ 5D (1) is substantially satisfied for each bent portion.

2. The number of bends in the pipe for pneumatic transport of the powdered aromatic dihydroxy compound is 50
A method for producing an aromatic polycarbonate, comprising:

3. The total distance of the pipes for pneumatic transport of the powdery aromatic dihydroxy compound is 500
m or less.

4. A method for producing an aromatic polycarbonate, comprising a combination of at least two of the group consisting of the method described in 1 above, the method described in 2 above, and the method described in 3 above.

The inventors of the present application focused on the fact that even when the aromatic dihydroxy compound in the powder was transported under an inert gas atmosphere, the color hue and the polymerization reactivity of the polymer were adversely affected, and as a result of intensive studies. The present inventors have found that a metal component is mixed into the aromatic dihydroxy compound of the powder, thereby deteriorating the hue of the polymer and lowering the polymerization reactivity, thereby completing the present invention.

Hereinafter, the method for producing an aromatic polycarbonate according to the present invention will be specifically described.

In the present invention, the aromatic polycarbonate is an aromatic diol compound which is a main component and a carbonic acid diester are converted to a transesterification catalyst comprising a basic nitrogen compound and an alkali metal compound and / or an alkaline earth metal compound. An aromatic polycarbonate melt-polycondensed in the presence.

Specific examples of the aromatic diol compound include bis (4-hydroxyphenyl) methane, 2,2-bis (4-hydroxyphenyl) propane, and 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 are listed, and 2,2-bis (4-hydroxyphenyl) propane is particularly preferred.

Specific examples of the carbonic acid diester include diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl)
Carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate and the like are used. Of these, diphenyl carbonate is particularly preferred.

The usage ratio of the two types of raw materials used in the present invention is from 1.00 to 1 in a raw material molar ratio expressed as a value obtained by dividing the number of moles of the carbonic acid diester compound by the number of moles of the aromatic dihydroxy compound. It is preferable to select from the range of .10.

Further, the aromatic polycarbonate of the present invention may be optionally used as an aliphatic diol, for example,
Ethylene glycol, 1,4-butanediol, 1,4
-Cyclohexanedimethanol, 1,10-decanediol and the like as dicarboxylic acids, for example, succinic acid,
Isophthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, cyclohexanecarboxylic acid, terephthalic acid and the like;
Oxy acids such as lactic acid, P-hydroxybenzoic acid, 6
-Hydroxy-2-naphthoic acid may be contained.

Although the catalyst used in the present invention is not particularly limited, a transesterification catalyst comprising a basic nitrogen compound and an alkali metal compound and / or an alkaline earth metal compound can be used.

The alkali metal and / or alkaline earth metal compound used in the present invention is not particularly limited as long as it does not lower the hue of the aromatic polycarbonate obtained, and various known compounds can be used. it can.

Examples of the alkali metal compound used as a catalyst include hydroxides, bicarbonates, carbonates, acetates, nitrates, nitrites, sulfites, cyanates, thiocyanates, stearate salts of alkali metals. Borohydride, benzoate, hydrogen phosphate, bisphenol, phenol salt and the like.

Specific examples 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, 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 phenylated borate, sodium benzoate, potassium benzoate, benzoate Examples thereof include lithium acid, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, disodium salt, dipotassium salt, dilithium salt of bisphenol A, sodium salt, potassium salt, and lithium salt of phenol.

The alkaline earth metal compound used as a catalyst includes, for example, hydroxides, bicarbonates, carbonates, acetates, nitrates, nitrites, sulfites, cyanates, thiocyanates of alkaline earth metals. , Stearates,
Benzoates, bisphenols, phenol salts and the like can be mentioned.

Specific examples include 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, strontium sulfite, calcium cyanate, barium cyanate, strontium cyanate, calcium thiocyanate, barium thiocyanate, Strontium thiocyanate, calcium stearate, barium stearate, strontium stearate, calcium borohydride, barium borohydride, water Boron strontium, calcium benzoate, barium benzoate, strontium benzoate, calcium salts of bisphenol A, a barium salt,
Strontium salts, calcium salts of phenol, barium salts, strontium salts and the like can be mentioned.

In the present invention, if desired, the alkali metal compound of the catalyst may be (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. Can be used. Here, the elements of Group 14 of the periodic table refer to silicon, germanium, and tin.

(A) As an alkali metal salt of an ate complex of an element of group 14 of the periodic table, those described in JP-A-7-268091 are mentioned. Specifically, a compound of germanium (Ge); NaGe (OMe) ₅ , NaGe
(OEt) ₃ , NaGe (OPr) ₅ , NaGe (OB
u) ₅ , NaGe (OPh) ₅ , LiGe (OMe) ₅ ,
LiGe (OBu) ₅ and LiGe (OPh) ₅ can be given.

As a compound of tin (Sn), NaSn
(OMe) ₃ , NaSn (OMe) ₂ (OEt), NaS
n (OPr) ₃ , NaSn (On-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.

(B) Examples of the alkali metal salt of an oxo acid of Group 14 element of the periodic table include silicic acid (silicic acid).
Cic acid), stannic acid (sta)
alkali metal salt of germanic acid, germanium (II) acid, germanic acid (germanic acid), germanic acid (germanic acid)
Alkali metal salts of acid) can be mentioned as preferred.

The alkali metal salt of silicic acid is, for example, an acidic or neutral alkali metal salt of monosilicic acid (monosilicic acid) or a condensate thereof, and examples thereof include monosodium orthosilicate, disodium orthosilicate, and orthosilicate. Trisodium and tetrasodium orthosilicate can be mentioned.

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

Germano (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 monogermanic acid (IV) acid or a condensate thereof, for example, monolithium orthogermanate (LiH ₃ GeO ₄ ) orthogermanic acid Disodium salt, tetrasodium orthogermanate, disodium digermanate (Na
₂ Ge ₂ O ₅ ), disodium tetragermanate (Na ₂ Ge ₄ O ₉ ), and disodium pentagermanate (Na ₂ Ge ₅ O ₁₁ ).

The alkali metal compound or alkaline earth metal compound used as the catalyst is such that the alkali metal element or alkaline earth metal element in the catalyst is 1 × 10 ^{−8 to} 5 × 10 ⁻⁵ equivalent per mole of the aromatic diol compound. It is preferably used in such a ratio. A more preferable ratio is a ratio that is 5 × 10 ⁻⁷ to 1 × 10 ⁻⁵ equivalents with respect to the same standard. Here, the term “equivalent” refers to the sum of the valences of the alkali metal element and the alkaline earth metal element contained in one molecule. The relationship between the mole and the equivalent is that one molecule contains one alkali metal element (monovalent). 1 mole is equal to 1 equivalent when used, and 1 mole is equal to 2 equivalents when one alkaline earth metal element (divalent) is included. When two alkali metal elements (monovalent) are contained in one molecule, one mole is equal to two equivalents. If the amount of the alkali metal element or the amount of the alkaline earth metal element in the catalyst deviates from 1 × 10 ^{−8 to} 5 × 10 ⁻⁵ equivalent per 1 mole of the aromatic diol compound, the physical properties of the obtained polycarbonate are adversely affected. And the transesterification does not proceed sufficiently to obtain a high molecular weight polycarbonate.

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 Ammonium hydroxides having alkyl, aryl, alkylaryl groups such as trimethylammonium hydroxide (φ-CH ₂ (Me) ₃ NOH), hexadecyltrimethylammonium hydroxide, triethylamine, tributylamine, dimethylbenzylamine, hexadecyl Tertiary amines such as dimethylamine, or tetramethylammonium borohydride (Me ₄ NB
H ₄ ), basic salts such as tetrabutylammonium borohydride (Bu ₄ NBH ₄ ), tetrabutylammonium tetraphenylborate (Me ₄ NBPh ₄ ), and tetrabutylammonium tetraphenylborate (Bu ₄ NBPh ₄ ). it can.

The nitrogen-containing basic compound is a nitrogen-containing basic compound.
Ammonium nitrogen atom in compound is aromatic diol compound
1 × 10 per mole of product^-Five~ 5 × 10^-3At the equivalent ratio
It is preferably used. A more desirable ratio is based on the same criteria.
2 × 10^-Five~ 5 × 10^-FourThis is the equivalent ratio. In particular
The preferred ratio is 5 × 10 for the same standard^-Five~ 5 × 10 ^-Four
This is the equivalent ratio.

In the specification of the present application, the ratio of an alkali metal compound, an alkaline earth metal compound and a nitrogen-containing basic compound to a charged aromatic diol compound (also referred to as an aromatic dihydroxy compound in the present specification) is referred to as “aromatic compound”. Z (compound name) equivalent of W (numerical value) as a metal or basic nitrogen per 1 mol of an aromatic dihydroxy compound, for example, when Z is sodium phenoxide or 2,2-bis (4-hydroxy If there is one sodium atom such as phenyl) propane monosodium salt or one basic nitrogen such as triethylamine, it means that the amount of Z is equivalent to W moles, , 2-bis (4-hydroxyphenyl) propane disodium salt, the amount is equivalent to W / 2 mol. It means the door.

In the polycondensation reaction of the present invention, at least one cocatalyst selected from the group consisting of an oxo acid of Group 14 element of the periodic table and an oxide of the same element is optionally used together with the above catalyst. Can coexist.

By using these co-catalysts in a specific ratio, the terminal blocking reaction and the polycondensation reaction rate are not impaired, the branching reaction which is easily generated during the polycondensation reaction, and the foreign matter in the apparatus at the time of molding are performed. Undesirable side reactions such as generation and burning can be more effectively suppressed.

As a result of the examination, in the production method of the aromatic polycarbonate, the curvature radius of the bent portion of the pipe for pneumatically transporting the aromatic dihydroxy compound of the powder is appropriately selected, and the number of the bent portions of the pipe is appropriately adjusted. It has been found that it is effective to obtain a polycarbonate having an excellent hue by keeping the total number of pipes to an appropriate length while keeping the total number of pipes to a suitable length.

Regarding the radius of curvature, when the inside diameter of the pipe at each bent portion is D (m) and the radius of curvature is R (m), R
It is preferable that the relationship of ≧ 5D is substantially satisfied for each bent portion in order to prevent deterioration of the hue of the polymer and to prevent a decrease in polymerization reactivity, more preferably R = 6 to 12D, and most preferably R = 9. It became clear that the radius of curvature of the pipe was about 11D.

The number of bent portions of the pipe is preferably 50 or less in order to prevent deterioration of the hue of the polymer and to prevent a decrease in polymerization reactivity, more preferably 10 or less.
It has been found that the pipe bending portion is most preferably 5 or less.

The total distance of the pipes is preferably 500 m or less in order to prevent deterioration of the hue of the polymer and to prevent a decrease in polymerization reactivity, more preferably 200 m.
Below, it became clear that it is most preferable to set the total piping distance to 100 m or less.

Although these reasons are not clear, it is supposed that they may be as follows.

That is, according to the study by the present inventors,
When polycarbonate is produced by melt-polymerizing an aromatic dihydroxy compound and a carbonic acid diester in the presence of a catalyst, unlike in the case of producing polycarbonate by an interfacial polymerization method, the hue and polymerization reactivity of the polymer from which the metal component is obtained are reduced. It has been found that this has a significant effect, and that the hue of the obtained polymer is deteriorated when the metal component is increased, and that the polymerization rate is greatly reduced in an extreme case.

For this reason, high purity is required for aromatic dihydroxy compounds and carbonic acid diesters used as raw materials for melt polymerization, and the carbonic acid diesters are obtained by distilling and purifying the distillate in a molten state under an inert gas atmosphere. , Which are used directly in the polymerization.

On the other hand, many aromatic dihydroxy compounds have poor thermal stability, so that they must be handled in a solid state. Therefore, impurities are liable to be mixed during the handling process.

For example, when an aromatic dihydroxy compound is pneumatically transported, friction and collision between the pipe and the powder of the aromatic dihydroxy compound occur, and the metal content of the aromatic dihydroxy compound due to the material of the apparatus with respect to the aromatic dihydroxy compound in the pneumatic transport process. Of the resulting polymer, resulting in a risk of deteriorating the hue of the resulting polymer and decreasing the polymerization rate.

The present invention is considered to improve the hue of the obtained polymer by suppressing the mixing of metal components caused by the device material during the pneumatic transport and maintaining the high-purity quality.

However, unfortunately, at this stage,
Analysis of the metal content in the aromatic dihydroxy compound does not show a clear change.

The shape of the aromatic dihydroxy compound used in the present invention is not particularly limited, but a spherically shaped product called prill or a flake-shaped product is preferably used.

In the present invention, the atmosphere for transporting the powdered aromatic dihydroxy compound is from the viewpoint of safety in preventing dust explosion and from the viewpoint of quality in preventing deterioration of the aromatic dihydroxy compound due to oxygen. An inert gas atmosphere is used, especially an inert gas atmosphere.

In the present invention, there is no particular limitation on the material of the piping and blower used for pneumatically transporting the aromatic dihydroxy compound, and general materials can be used. For example, stainless steel such as SUS304 or SUS316 is preferable. used. In addition, when iron is used for the blower for reasons such as work, install a filter with openings of 10 μm or less on the outlet side of the blower,
It is also preferable to remove foreign substances such as rust.

The thus-transported aromatic dihydroxy compound is mixed and dissolved in a predetermined mixing ratio with a carbonic acid diester by a known method, and then melt-polymerized by a known method to obtain a polycarbonate having an excellent hue. Can be manufactured.

In the present invention, the polycarbonate obtained by the above method can be subjected to a catalyst deactivator addition treatment and a devolatilization treatment using a vented twin-screw ruder. At this time, the polycarbonate may be supplied to the ruder in a molten state directly from the polymerization machine, or may be cooled and pelletized once and supplied to the ruder.

As the deactivator used in the present invention, known deactivators are effectively used. Among them, ammonium salts and phosphonium salts of sulfonic acid are preferable, and further, tetrabutylphosphonium salt of dodecylbenzenesulfonic acid and the like are preferable. The above salts of dodecylbenzenesulfonic acid and the above salts of paratoluenesulfonic acid such as tetrabutylammonium paratoluenesulfonate are preferred. As sulfonic acid esters, methyl benzenesulfonate, ethyl benzenesulfonate, butylbenzenesulfonate, octylbenzenesulfonate, phenylbenzenesulfonate, methyl paratoluenesulfonate, ethyl paratoluenesulfonate, butylparatoluenesulfonate, para Octyl toluenesulfonate, phenyl paratoluenesulfonate and the like are preferably used, and among them, tetrabutylphosphonium dodecylbenzenesulfonate is most preferably used.

These deactivators are used in an amount of 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, more preferably in a ratio of 0.8 to 5 mol.

These deactivators are added directly to the melted polycarbonate and kneaded, or dissolved or dispersed in an appropriate solvent.

In the present invention, other additives can be added to the polycarbonate as long as the object of the present invention is not impaired.

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

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

For the purpose of the processing stabilizer, heat stabilizer, antioxidant and the like used in the present invention, for example, phosphorus compounds, phenolic stabilizers, organic thioether stabilizers,
Hindered amine stabilizers and the like can be mentioned.

As the light stabilizer and the ultraviolet absorber, general ultraviolet absorbers are used, for example, salicylic acid ultraviolet absorber, benzophenone ultraviolet absorber, benzotriazole ultraviolet absorber, cyanoacrylate ultraviolet absorber. Agents and the like.

As the release agent, generally known release agents can be used, for example, hydrocarbon release agents such as paraffins, fatty acid release agents such as stearic acid, stearamide and the like. Fatty acid amide release agents, alcohol release agents such as stearyl alcohol and pentaerythritol, fatty acid ester release agents such as glycerin monostearate, and silicone release agents such as silicone oil.

As the colorant, an organic or inorganic pigment or dye can be used.

As the metal deactivator, for example, N, N '
-[3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and the like; and metal soaps such as calcium stearate and nickel stearate.

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 sorbitols such as sodium di (4-t-butylphenyl) phosphonate, dibenzylidene sorbitol, and sodium salt of methylenebis (2,4-di-t-butylphenol) acid phosphate; Salt-based compounds are exemplified.

Examples of the lubricant include erucamide and stearic acid monoglyceride, and examples of the flame retardant include halogen-containing phosphoric esters such as tris (2-chloroethyl) phosphate, hexabromocyclododecane, decabromophenyl oxide and the like. And metal inorganic compounds such as 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 dissolved or dispersed in an appropriate solvent or polymer, or as master pellets. There is no particular limitation on the equipment used to perform such an operation, but for example, a twin-screw extruder or the like is preferable, and when the additive is supplied in the form of a solution, a metering pump such as a plunger pump is used. When the additives are supplied in the form of a master polymer, a side feeder or the like is generally used. When the additives are dissolved or dispersed in a solvent, a twin-screw extruder with a vent is particularly preferably used.

[0075]

According to the present invention, hue, hue stability,
An aromatic polycarbonate having excellent heat stability and excellent transparency can be efficiently produced without lowering the polymerization rate.

The following is a description of an embodiment. However, the present invention is not limited to these examples. The percentages and parts in the examples are% by weight or parts by weight unless otherwise specified. The physical properties of the polycarbonate obtained in the following Examples were measured as follows.

[Measurement of color tone (b value)] Polycarbonate pellets (short diameter × long diameter × length (mm)) = 2.5 × 3.
Lab value of 3 × 3.0) was determined by Nippon Denshoku Industries ND-100.
The value was measured by the reflection method using 1DP, and the b value was used as a measure of the yellowness.

[Measurement of Thermal Hue Deterioration (ΔE)] The obtained polymer was retained for 10 minutes in a molding machine at 340 ° C., and the polymer which was not retained was (minor diameter × long diameter × length). (Mm)) = 2.5 × 3.3 × 3.0), and the Lab value was determined by Nippon Denshoku Industries ND-1001D.
The measurement was performed by the reflection method using P and calculated using the following equation. ΔE = ((L ₂ −L ₁ ) ² + (a ₂ −a ₁ ) ² + (b ₂ −
b ₁₎ ^{2) 1/2}

[Example 1] Melt polycondensation of an aromatic polycarbonate was carried out using the following reaction equipment.

The aromatic dihydroxy compound transport / storage facility is made of SUS304 and has a rotary valve, and a hopper for receiving the powdered aromatic dihydroxy compound from the ton bag, and an inert gas for the powdered aromatic dihydroxy compound in the hopper. For transporting under an atmosphere, the total distance of the pipes is 80 m, the number of bent pipes is three, the radius of curvature of the bent pipes is R = 10D (D = 0.081 m), and the blower is blown under an inert gas atmosphere. A hopper for receiving the transported aromatic dihydroxy compound.

A raw material pump and a polymerization catalyst are prepared, which are capable of metering the aromatic dihydroxy compound and the carbonic acid diester, respectively, metering and mixing the mixture by heating, melting, and stirring. A catalyst preparation tank for performing the polymerization, a catalyst pump capable of supplying a constant amount of the catalyst solution to the initial polymerization tank, and a polymerization having a later polymerization tank for further polymerizing the prepolymer obtained in the initial polymerization tank to produce a polymer having a predetermined polymerization degree. The melt polycondensation reaction was continuously performed using the apparatus. The aromatic polycarbonate exiting the late polymerization tank was supplied to a twin-screw ruder by a gear pump, continuously extruded from a die into a strand, and then pelletized by a cutter.

The initial polymerization tank was provided with a rectification column provided with a reflux mechanism for separating a monohydroxy compound generated by the reaction and a carbonic acid diester as a raw material.

The reaction solution in the initial polymerization tank was continuously supplied to the latter polymerization tank by a gear pump.

The latter polymerization tank did not have a rectification column, and a jacket was provided on the whole.

The operating conditions of the melt polycondensation are shown below.

Bisphenol A was used as the aromatic dihydroxy compound, and diphenyl carbonate was used as the carbonic acid diester.

First, diphenyl carbonate and bisphenol A were supplied to a monomer mixture preparation tank in a molar ratio of diphenyl carbonate / bisphenol A = 1.01, and were stirred, mixed and dissolved.

As a polymerization catalyst, a disodium salt of bisphenol A was used. The catalyst, in the catalyst preparation tank,
Phenol / water = such that the catalyst concentration becomes 30 ppm
It was dissolved in a 90/10% by weight mixture.

While continuously supplying the raw material to the first tank, the catalyst solution was supplied such that the disodium salt of bisphenol A was 1 μ equivalent per mole of bisphenol A in the raw material,
Continuous melt polycondensation was performed.

The operation conditions of each polymerization tank are as follows: the initial polymerization tank has an internal temperature of 250 ° C., a degree of vacuum of 30 Torr, and the late polymerization tank has a
The temperature was 0 ° C. and the degree of vacuum was 0.5 Torr.

The operating time was 600 hours in a row. Polycarbonate samples were taken at the end of the late polymerization vessel at a frequency of once / day and evaluated for quality. The results are shown in Table 1.

[Comparative Example 1] In the apparatus of Example 1, a pipe for pneumatically transporting powdered bisphenol A was changed to Example 1 except that the radius of curvature of the bent portion of the pipe was R = 4.5D. Continuous operation was carried out for 600 hours under the same apparatus and under the same temperature conditions. However, a decrease in the reaction rate was observed, so that the degree of vacuum in the initial polymerization tank was 29 Torr and the degree of vacuum in the latter polymerization tank was 0.45 Torr.

A polycarbonate sample was collected at the outlet of the late polymerization tank at a frequency of once / day and evaluated for quality. The results are shown in Table 1.

[Comparative Example 2] In the apparatus of the example, a pneumatic transport of bisphenol A as a powder was carried out.
A continuous operation was performed for 600 hours under the same apparatus and the same temperature conditions as in Comparative Example 1 except that the number of the pipe bent portions was changed to 60, but the reduction in the reaction rate was observed, so that the degree of vacuum in the initial polymerization tank was 27 Torr. , The degree of vacuum in the late polymerization tank is 0.4 To
rr.

A polycarbonate sample was taken at the end of the late polymerization tank at a frequency of once / day and evaluated for quality. The results are shown in Table 1.

[Comparative Example 3] In the apparatus of the example, a pneumatic transport of powdered bisphenol A was carried out.
The continuous operation was performed for 600 hours under the same apparatus and the same temperature conditions as in Comparative Example 2 except that the total distance of the pipes was changed to 600 m. However, since the reaction rate was reduced, the degree of vacuum in the initial polymerization tank was 25 Torr, and the late polymerization was performed. The degree of vacuum in the tank is 0.3 Torr
r.

A polycarbonate sample was taken at the end of the late polymerization tank at a frequency of once / day and evaluated for quality. The results are shown in Table 1.

[0098]

[Table 1]

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toru Sawaki 2-1 Hinode-cho, Iwakuni-shi, Yamaguchi Prefecture Teijin Co., Ltd. Inside the Iwakuni Research Center (72) Inventor Katsuji Sasaki 2-1 Hinode-cho, Iwakuni-shi, Yamaguchi Prefecture Teijin Shares F-term in the Iwakuni Research Center of the Company (reference)

Claims (4)

[Claims] 1. A process for melt-polycondensing a carbonic acid diester and an aromatic dihydroxy compound in the presence of a catalyst to produce an aromatic polycarbonate. When the inner diameter of the pipe at the bent portion is D (m) and the radius of curvature is R (m), the following formula (1) R ≧ 5D (1) is substantially satisfied for each bent portion. A method for producing an aromatic polycarbonate. 2. A method for producing an aromatic polycarbonate, wherein the number of bent portions of a pipe for pneumatically transporting a powdery aromatic dihydroxy compound is 50 or less. 3. A method for producing an aromatic polycarbonate, wherein the total distance of a pipe for pneumatically transporting a powdery aromatic dihydroxy compound is 500 m or less. 4. A method for producing an aromatic polycarbonate, comprising a combination of at least two of the group consisting of the method according to claim 1, the method according to claim 2, and the method according to claim 3.