JP2003201343A - Method for producing aromatic polycarbonate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently producing a polycarbonate of excellent quality by eliminating a difficulty in controlling a mole balance of starting materials used in melt polymerization. <P>SOLUTION: The method for producing an aromatic polycarbonate is one comprising blending and melting a carbonic diester and a pneumatically conveyed powdery aromatic diydroxy compound under conditions in which the variation width is within at most ±0.005 in the range in which the molar ratio of the aromatic dihydroxy compound to the carbonic diester is 1 to (1.00-1.10) and polycondensing the melt in the presence of a transesterification catalyst, wherein the aromatic dihydroxy compound used is one which is in the form of flakes or prills having an angle of repose of 35-50° and shows an increment in an angle of repose of at most 10° after the pneumatic conveying. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polycarbonate resin, and more particularly to a method for stably and economically producing a polycarbonate having good quality by melt polymerization.

[0002]

2. Description of the Related Art Aromatic polycarbonate resins are widely used as molding materials because they have excellent mechanical properties such as impact resistance, heat resistance and transparency. As a method for producing such an aromatic polycarbonate resin, a method of directly reacting an aromatic dihydroxy compound such as bisphenol with phosgene (interfacial method), or an aromatic dihydroxy compound such as bisphenol and a carbonic acid diester such as diphenyl carbonate are used. A method of transesterification (melting method) is known. Among these production methods, the method of producing a polycarbonate by transesterification of an aromatic dihydroxy compound and a carbonic acid diester is an environmentally friendly method because it does not use harmful phosgene or methylene chloride, and is cost effective. In particular, the possibility of surpassing the interfacial method has been pointed out and attracting attention. However, there is a problem that the quality of polycarbonate obtained by the melting method does not reach that of the interfacial method in terms of hue, branching, gel, etc. due to severe reaction conditions, etc., and various investigations have been made to solve it. It has been. In the process, it was clarified that strictly controlling the molar balance between the aromatic dihydroxy compound and the carbonic acid diester, which are the two kinds of raw materials used in the melting method, is one effective method. However, it is difficult to strictly control the molar balance, and a great deal of labor is required to achieve this.

[0003]

The reason why a polycarbonate of excellent quality can be obtained by strictly controlling the molar balance of the raw materials in the melting method is the polymerization by the transesterification reaction involving the end groups of the two raw materials. It is considered that the polymerization rate is increased when the concentrations of the both agree with each other, and as a result, the time (thermal history) exposed to severe polymerization conditions is shortened. Since the terminal group concentration generally decreases as the polymerization progresses, and the polymerization conditions generally become more severe as the polymerization progresses, it is necessary to maintain a proper molar balance of the terminals even when the terminal group is reduced. Is important, and strict control of the molar balance is required for this purpose.

Particularly in recent years, polycarbonate has been used for DVD and M.
It has been used for optical products that require high density and high precision such as O and CDR. In this case, coloring, branching and gel of polycarbonate directly affect the optical properties such as block error rate of the final product and tensile and bending. Since the mechanical properties such as toughness are greatly affected, the importance of raw material molar balance control is increasing in order to avoid this problem.

On the other hand, since many aromatic dihydroxy compounds used as raw materials have high melting points and poor stability in a molten state, handling by powder is preferably used. Difficult to compare.

It is considered that these factors increase the difficulty of controlling the raw material molar balance in the melt polymerization. Therefore, an object of the present invention is to provide a production method for improving the above-mentioned problems of the prior art and efficiently obtaining a polycarbonate of excellent quality.

[0007]

The present invention is as follows. 1. The carbonic acid diester and the pneumatically transported powdered aromatic dihydroxy compound are mixed in a molar ratio of the aromatic dihydroxy compound to the carbonic acid diester of 1 to 1.0.
In the method for producing an aromatic polycarbonate by mixing and dissolving while maintaining a fluctuation range of ± 0.005 or less in the range of 0 to 1.10, and then performing melt polycondensation in the presence of a transesterification catalyst, flakes or prills are used. Angle of repose 3 with the shape of
1. A method for producing an aromatic polycarbonate, which comprises using an aromatic dihydroxy compound having an angle of repose increase of 10 ° or less after pneumatically transporting the aromatic dihydroxy compound at 5 ° to 50 °. The carbonic acid diester and the pneumatically transported powdered aromatic dihydroxy compound are mixed in a molar ratio of the aromatic dihydroxy compound to the carbonic acid diester of 1 to 1.0.
In a method for producing an aromatic polycarbonate by mixing and dissolving while maintaining a fluctuation range of ± 0.005 or less in a range of 0 to 1.10, and then performing melt polycondensation in the presence of a transesterification catalyst, 2. A method for producing an aromatic polycarbonate, characterized in that an aromatic dihydroxy compound having a charge amount after pneumatic transport of 100 kV or less is used as the aromatic dihydroxy compound. When the velocity of the aromatic dihydroxy compound in the pipe for pneumatically transporting the powdery aromatic dihydroxy compound is A (kg / hr) and the velocity of the inert gas as the transport medium is B (kg / hr), The above-mentioned 1 is characterized by using an aromatic dihydroxy compound pneumatically transported under the condition that the relation of the following formula (1) 15 ≧ A / B ≧ 3 (1) is established.
3. The method for producing an aromatic polycarbonate according to any one of items 1 to 3, The wind velocity of an inert gas, which is a transport medium for pneumatically transporting the powdery aromatic dihydroxy compound, is 10 m / S or more and 40 m / S or less in the mixed portion of the aromatic dihydroxy compound. 1-3
4. The method for producing an aromatic polycarbonate according to 5. The dew point of an inert gas, which is a transport medium for pneumatically transporting powdery aromatic dihydroxy compounds, is −
5. The method for producing an aromatic polycarbonate described in 1 to 4 above, wherein the temperature is 1 ° C. or lower. Production of the aromatic polycarbonate according to any one of 1 to 5 above, wherein the oxygen concentration in the inert gas, which is a transport medium for pneumatically transporting the powdery aromatic dihydroxy compound, is 3% or less. Method 7. 0.5 μm of an inert gas as a transport medium for pneumatically transporting powdery aromatic dihydroxy compounds
The method for producing an aromatic polycarbonate described in any one of 1 to 6 above, wherein the foreign matter content is 10,000 pieces / m ³ or less.

The aromatic dihydroxy compound used in the present invention is, for example, 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, with 2,2-bis (4-hydroxyphenyl) propane being particularly preferable.

Examples of the carbonic acid diester used in the present invention include diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate, dimethyl carbonate,
Diethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, etc. are used. Of these, diphenyl carbonate is particularly preferable.

The catalyst used in the present invention is not particularly limited, but a transesterification catalyst composed of 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 reduce the hue of the aromatic polycarbonate obtained, and various known compounds can be used. it can.

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, benzoate salts, phosphohydrides, bisphenols, phenol salts 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 phenyl borate, sodium benzoate, potassium benzoate, benzoin Examples thereof include lithium acid salt, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, disodium salt of bisphenol A, dipotassium salt, dilithium salt, sodium salt of potassium, potassium salt and lithium salt.

Examples of the alkaline earth metal compound used as the catalyst include hydroxides, hydrogen carbonates, carbonates, acetates, nitrates, nitrites, sulfites, cyanates and thiocyanates of alkaline earth metals. , Stearate,
Examples thereof include benzoate, bisphenol, and phenol salt.

As specific examples, 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,
Examples thereof include strontium salt, calcium salt of phenol, barium salt, and strontium salt.

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

(A) Alkali metal salts of ate complexes of Group 14 elements of the periodic table include those described in JP-A-7-268091, 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 ,
Examples thereof include LiGe (OBu) ₅ and LiGe (OPh) ₅ .

The compound of tin (Sn) is 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 (b) an oxo acid of Group 14 element of the periodic table 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, and examples thereof include monosodium orthosilicate, disodium orthosilicate, orthosilicic acid. Mention may be made of trisodium 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 = 0~5)} , mention may be made of Monosuzu acid tetrasodium salt (Na ₄ SnO _4).

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 ).

The alkali metal compound or the alkaline earth metal compound as the catalyst is 1 × 10 ^{-8 to} 5 × 10 ^-5 equivalents of the alkali metal element or the alkaline earth metal element in the catalyst per mol of the aromatic diol compound. It is preferably used when A more preferable ratio is a ratio of 5 × 10 ⁻⁷ to 1 × 10 ⁻⁵ equivalent based on the same standard.

When the amount of the alkali metal element or the amount of the alkaline earth metal element in the catalyst deviates from the range of 1 × 10 ^{-8 to} 5 × 10 ^-5 equivalents per mol of the aromatic diol compound, the obtained aromatic polycarbonate is It is not preferable because it has various problems such as adversely affecting various physical properties, the transesterification reaction does not proceed sufficiently, and a high molecular weight aromatic polycarbonate cannot be obtained.

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.
When the ammonium nitrogen atom in the compound is combined with an aromatic diol compound
1 x 10 per mole of product^-Five~ 5 x 10^-3At the rate of equivalent
It is preferably used. A more desirable ratio is based on the same criteria.
2 x 10^-Five~ 5 x 10^-FourIt is the ratio of equivalent weight. In particular
Preferred ratio is 5 × 10 based on the same criteria^-Five~ 5 x 10 ^-Four
It is the ratio of equivalent weight.

In the present specification, a charged aromatic diol compound (also referred to as an aromatic dihydroxy compound)
The ratio of the alkali metal compound, the alkaline earth metal compound and the nitrogen-containing basic compound with respect to
(Numerical value) equivalent Z (compound name) amount ”,
This is because, for example, Z is sodium phenoxide or 2,2
Z has one sodium atom such as bis (4-hydroxyphenyl) propane monosodium salt or one basic nitrogen such as triethylamine, Z
Means that the amount of W is equivalent to W mol.
If it is two such as -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, if necessary, 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 together with the above catalyst. Can coexist.

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

In the present invention, the temperature and pressure for transesterifying the aromatic dihydroxy compound and the carbonic acid diester are not particularly limited, the reaction starts, and the monohydroxy compound produced by the reaction is rapidly removed to the outside of the reaction system. Any conditions may be used as long as the temperature and pressure are
Temperature of 0 ° C to 200 ° C and 300 Torr to 100To
After starting the reaction at a pressure of rr, the reaction temperature is increased as the molecular weight of the polycarbonate increases with the progress of the reaction,
It is general to lower the reaction pressure and finally carry out the reaction at a temperature of 270 to 350 ° C. and a pressure of 1 Torr or less.

There is no particular limitation on the form of equipment for carrying out the present invention, and either a batch system or a continuous system can be carried out. When performing in batch mode, usually two reactors are installed in series,
The reaction is carried out under different conditions using a stirring tank with a rectification tower installed in the former and a stirring tank without a rectification tower installed in the latter. In this case, it is preferable that both are connected by a pipe equipped with a valve, the former reaction product is transferred to the latter without exposure to the outside air, and the latter reaction is carried out to a desired degree of polymerization.

When carrying out in a continuous system, usually two or more reactors are installed in series, adjacent reactors are connected by a pipe equipped with a valve, and a pump for transferring the reaction solution is used as necessary. Using the equipment provided, continuously supplying the raw material and catalyst to the first reactor while maintaining each reactor under different conditions,
It is carried out by continuously withdrawing a polycarbonate having a desired degree of polymerization from the last reactor.

In the present invention, the molar ratio of the carbonic acid diester to the aromatic dihydroxy compound used is 1.0 to
A range of 1.1 is preferred.

According to the studies by the present inventors, it has been found that maintaining the molar ratio selected from the above range with high precision is extremely important for producing a polycarbonate having good quality. That is, in order to achieve the object of the present invention, the fluctuation range of the molar ratio is within ± 0.005, preferably ± 0.005.
It is necessary to maintain it within 0.003.

By improving the accuracy of setting the molar ratio,
The reason why the quality of the polymer including the hue is improved is not critical, but since the molar ratio of the raw materials has a large influence on the polymerization rate, it is possible to increase the accuracy of the molar ratio to prevent excessive reaction conditions, for example, the polymerization reaction time. It is considered that it is possible to avoid conditions that deteriorate the polymer quality, such as lengthening the temperature, increasing the polymerization reaction temperature, and increasing the amount of the polymerization catalyst, which leads to the improvement of the quality.

According to the studies made by the present inventors, it has been found that it is not enough to use the commonly used high-accuracy weighing system to achieve these goals. That is, in many cases, the carbonic acid diester excellent in the thermal stability of the melt is measured in a liquid state, and for example, the use amount control using a highly accurate flow meter is used. In addition, the aromatic dihydroxy compound, which is poor in thermal stability, is often measured in a powder state after being pneumatically transported. For example, the aromatic dihydroxy compound of the powder is placed in a weighing tank insulated from the surroundings by weight. It is carried out by accepting a compound, discharging it using a screw feeder or the like, and measuring its weight with a load cell or the like. It is known that these weighing systems have sufficient weighing accuracy within an error of 0.5% by themselves, but even if such high-precision weighing equipment is used, the above-mentioned strict molar balance is achieved. Is difficult to do.

That is, in the process of pneumatic transport, the aromatic dihydroxy compound is repeatedly crushed due to collision with the wall surface of the pipe and collision of the powder particles with each other, and therefore contains a large amount of fine powder. These fine powders, after being weighed in the weighing system, are attached to the wall surface of the pipe that is transferred to the mixing and dissolving tank with the carbonic acid diester, and are then discharged to the mixing and dissolving tank with the measured weight and the carbonic acid diester. The amount of fine particles of the aromatic dihydroxy compound adhering to the wall surface of the pipe will increase, and eventually the clogging of the pipe will be a serious problem in the entire production system. It can also have an impact.

In the present application, the fine powder of aromatic dihydroxy compound means particles having a diameter of 250 μm or less.

The first method for producing an aromatic polycarbonate according to the present invention is a pneumatic transport obtained by pneumatically transporting an aromatic dihydroxy compound having a flake or prill shape and an angle of repose of 35 ° to 50 °. It is represented by using a powdery aromatic dihydroxy compound having an increase in the angle of repose of 10 ° or less. In the first measure of the present invention, the increase in the angle of repose due to pneumatic transportation is 6 °.
It is further preferred to use the following:

According to the study by the present inventors, the amount of fine powder in the powder after the pneumatic transport of the aromatic dihydroxy compound increases with the increase in the angle of repose of the aromatic dihydroxy compound after the pneumatic transport. It was found to show an increasing tendency, and when the amount of increase in the angle of repose of the aromatic dihydroxy compound after pneumatic transport was 11 ° or more, it was extremely difficult to achieve the strict molar balance presented in the present application. Becomes

In the present application, the angle of repose of an aromatic dihydroxy compound is measured by an injection method in which a standard sieve is vibrated and a sample is passed through a funnel.

The second method for producing an aromatic polycarbonate of the present invention is specified by using an aromatic dihydroxy compound having a charge amount of 100 kV or less after pneumatically transporting the powdery aromatic dihydroxy compound. To be done. In the second measure, it is more preferable to use an aromatic dihydroxy compound having a charge amount of 30 kV or less.

That is, when the pneumatically transported aromatic dihydroxy compound has a certain charge or more, the fine powder of the aromatic dihydroxy compound directly or on the wall surface of the pipe for transferring the aromatic dihydroxy compound from the measuring system to the mixing and dissolving tank. The phenomenon of electrostatic adhesion via the already-attached aromatic dihydroxy compound is observed, which amplifies the adhesion of the aromatic dihydroxy compound to the wall surface of the pipe and achieves the strict molar balance presented in this application. It becomes more difficult.

The present invention is not particularly limited to the method for producing the powder of the aromatic dihydroxy compound having such characteristics, but the above-mentioned method is carried out by pneumatically transporting the aromatic dihydroxy compound under the following conditions. An aromatic dihydroxy compound having the above feature can be preferably obtained.

In the present invention, the aromatic dihydroxy compound before pneumatic transport has a flake or prill shape and preferably has an angle of repose of 35 ° to 50 °. By using such an aromatic dihydroxy compound, stable pneumatic transport can be performed.

In the present invention, when pneumatically transporting the above-mentioned aromatic dihydroxy compound, the rate of the aromatic dihydroxy compound in the pipe is A (kg / h).
r), the velocity of the inert gas as the transport medium is B (kg / h)
In the case of r), the following formula (1) 15 ≧ A / B ≧ 3 (1) is satisfied, and more preferably 15 ≧ A / B
It is important to carry out pneumatic transport under the condition that the relation ≧ 6 holds. In the present application, a value obtained by dividing the velocity A (kg / hr) of the aromatic dihydroxy compound by the velocity B (kg / hr) of the inert gas that is the transport medium is hereinafter referred to as a mixing ratio in pneumatic transport. .

In the study by the present inventors, when the aromatic dihydroxy compound was pneumatically transported, if the mixing ratio in the pneumatic transport was gradually increased, the amount of fine powder in the aromatic dihydroxy compound after the pneumatic transport was increased. It was found that there was a decreasing tendency, the increase in the angle of repose was suppressed, and the charge amount also decreased.

Although the cause of this is not clear, when the density of the aromatic dihydroxy compound in the inert gas, which is a transport medium, becomes high, the degree of freedom of the aromatic dihydroxy compound powder is limited. During this period, the state becomes static, and the amount of fine powder in the aromatic dihydroxy compound after pneumatic transport is reduced due to the reduction of crushing due to the mutual collision of powders, the increase in the angle of repose is suppressed, and the charge amount is also reduced. It is supposed to do.

Further, in the present invention, the wind velocity in the transport pipe of the inert gas, which is a medium for pneumatically transporting the powdery aromatic dihydroxy compound, is 10 m / S or more in the mixed portion of the aromatic dihydroxy compound, 40m /
It is extremely important that it is S or less, and more preferably 10 m / S or more and 20 m / S or less.

That is, when the air velocity in the pipe of the inert gas, which is a transport medium for pneumatically transporting the powdery aromatic dihydroxy compound, becomes slow, the transport velocity of the aromatic dihydroxy compound also decreases at the same time, and the transport pipe bent portion By reducing the collision speed of the inside of the, the degree of pulverization of the aromatic dihydroxy compound is reduced, as a result, the amount of fines in the aromatic dihydroxy compound after pneumatic transport is reduced,
It is considered that the increase of the angle of repose is suppressed and the charge amount is also reduced. However, if the velocity of the inert gas in the pipe is slowed down beyond the scope of the present invention, the aromatic dihydroxy compound will be precipitated and transport failure will occur, which is not preferable.

In the present invention, it is important that the dew point of the inert gas, which is a transport medium for pneumatically transporting the powdery aromatic dihydroxy compound, be -1 ° C or lower, and more preferably -30 ° C. The following is to be done.

When the pneumatically transported aromatic dihydroxy compound is weighed in the weighing system and then transferred to the mixing and dissolution tank with the carbonic acid diester, fine particles of the aromatic dihydroxy compound adhere to the wall surface of the transfer pipe. The cause may be adhesion due to viscosity in addition to electrostatic adhesion.

According to the study by the inventors of the present application, it has been clarified that the fine powder of the aromatic dihydroxy compound having a water content has a viscosity, and based on this finding, the aromatic dihydroxy compound of the powder is pneumatically transported. By lowering the dew point of the inert gas, which is the transport medium for this purpose, we succeeded in eliminating the viscosity of the fine powder.

In the present invention, it is important that the oxygen concentration in the inert gas, which is a transport medium for pneumatically transporting the powdery aromatic dihydroxy compound, is 3% or less, and more preferably 1. It is important to keep the percentage below.

When the aromatic dihydroxy compound is handled, the transportation atmosphere is usually set so that the oxygen concentration in the inert gas is 5% or less in order to prevent dust explosion.

However, even when the oxygen concentration in the inert gas is kept at 5% or less, there is a problem that the hue of the polymer is deteriorated, and as a result of earnest research, oxygen in the inert gas is found. By further reducing the concentration, we succeeded in improving the hue of the polymer.

The reason for this is not clear, but it is considered that the oxygen remaining in the inert gas causes the aromatic dihydroxy compound to oxidize and discolor, thereby deteriorating the hue of the polymer.

In the present invention, the content of foreign matter of 0.5 μm or more in the inert gas, which is a transport medium for pneumatically transporting the powdery aromatic dihydroxy compound, is 1 or more.
It is important that the number is 0000 pieces / m ³ or less, and more preferably that the content of foreign matter of 0.5 μm or more is 5000 pieces / m ³ or less. Conventionally, it has been known that such minute foreign substances exist in a molten raw material or a reaction product obtained by polymerization. However, a large amount of melt is treated with a precise filter having an opening of 0.5 μm or less. Filtration is difficult from the viewpoint of pressure loss, and the current situation is that no special measures have been taken.

However, the inventors of the present invention filtered the inert gas used for pneumatic transportation with a precision filter having an opening of 0.5 μm or less to reduce the foreign matter content of 0.5 μm or more. By using an aromatic dihydroxy compound pneumatically transported by using such an inert gas, a minute foreign substance of 0.5 μm or more present in a molten raw material or a reaction product obtained by polymerization is significantly reduced. It was found to decrease.

Although the cause of this is not clear, in the pneumatic transport, the aromatic dihydroxy compound becomes uniformly dispersed in the inert gas, and in combination with charging during the transport process, minute foreign matters contained in the inert gas are generated. It is easily adsorbed by the aromatic dihydroxy compound. As a result, it is considered that the amount of minute foreign matters of 0.5 μm or more present in the raw material obtained by melting the transported aromatic dihydroxy compound or the reaction product obtained by polymerization is greatly influenced.

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 vent type biaxial ruder. 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 deactivator used in the present invention, known deactivators 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 paratoluenesulfonate, ethyl paratoluenesulfonate, butyl paratoluenesulfonate, octyl paratoluenesulfonate, phenyl paratoluenesulfonate, etc. are preferably used, and among them, dodecylbenzenesulfonic acid tetrabutylphosphonium salt is most preferably used. To be done.

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

Further, in the present invention, other additives may be added to the polycarbonate within a 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 paraffins, 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 and dyes can be used.

Examples of the metal deactivator include N and 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 methylsulfate, and alkyl phosphate compounds.

Examples of the nucleating agent include sorbitol compounds such as sodium di (4-t-butylphenyl) phosphonate, dibenzylidene sorbitol, sodium methylenebis (2,4-di-t-butylphenol) acid phosphate, 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 and decabromophenyl oxide. And the like, metal inorganic compounds such as antimony trioxide, antimony trioxide, antimony pentoxide, and aluminum hydroxide, and mixtures thereof.

These additives are added or kneaded to the polycarbonate in a molten state 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.

[0078]

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. (Hue) Color and made by Nippon Denshoku Industries Co., Ltd.
Color Difference Meter N
Color b was measured using D-1001DP. (End group structure) OH for all end groups by NMR measurement method
The ratio (%) of terminal groups was determined. (Intrinsic viscosity and viscosity average molecular weight) A 0.7 g / dl methylene chloride solution was used to measure the intrinsic viscosity using an Ubbelohde viscometer, and the viscosity average molecular weight was determined by the following formula. [Η] = 1.23 × 10 ⁻⁴ M ^0.83 (content of foreign matter of 0.5 μm or more) 40 g of pellets was dissolved in 2 L of methylene chloride, and the amount of foreign matter was counted by a light scattering and blocking method. The results were converted to pieces / g.

[Example 1] Using the following reaction equipment, melt polycondensation of an aromatic polycarbonate was carried out. [Transportation of Aromatic Dihydroxy Compound] A first hopper made of SUS304 and equipped with a rotary valve to receive a powdered aromatic dihydroxy compound from a ton bag, and a blower for pneumatically transporting the aromatic dihydroxy compound in the hopper. An aromatic dihydroxy compound transportation / storage facility comprising a pipe provided and a second hopper for receiving the pneumatically transported aromatic dihydroxy compound was used.

In the pneumatic transport, the mixing ratio of the aromatic dihydroxy compound and the inert gas was 12, and the wind velocity of the inert gas was 15 m / S at the mixing portion of the aromatic dihydroxy compound (outlet of the first hopper). .

The oxygen concentration of nitrogen, which is a transport medium for pneumatic transport, is 0.8%, and the dew point is -60.
The content of foreign matter of 0.5 μm or more at ³ ° C. was 3200 pieces / m ³ .

Using the above equipment and method, prill-like bisphenol A having an angle of repose of 40 ° was received from the ton bag into the first hopper and pneumatically transported to the second hopper. As a result, the angle of repose was 46 ° and the charge amount was A powdery bisphenol A of 5 kV was obtained. [Production of Polycarbonate] Aromatic dihydroxy compound from the second hopper and molten carbonic acid diester from the molten carbonic acid diester storage tank are metered and heated and melted.
A monomer mixture preparation tank that can be mixed with stirring, a raw material pump that can continuously supply a fixed amount of raw material to the initial polymerization tank, a catalyst preparation tank for preparing a polymerization catalyst, and a constant supply of a catalyst solution to the initial polymerization tank The melt polycondensation reaction was continuously carried out using a catalyst pump and a polymerization apparatus having a late polymerization tank for further polymerizing the prepolymer obtained in the initial polymerization tank to produce a polymer having a predetermined degree of polymerization. The aromatic polycarbonate discharged from the latter-stage polymerization tank was supplied to a biaxial ruder by a gear pump, continuously extruded from a die, and then formed into pellets by a cutter.

In this equipment, the initial polymerization tank was equipped with a rectification column equipped with a reflux mechanism for separating the monohydroxy compound generated in the reaction and the carbonic acid diester as a raw material. It was a stirring tank, and was connected to the latter polymerization tank by a pipe equipped with a gear pump for continuously supplying the reaction liquid obtained in the first polymerization tank to the latter polymerization tank.

The latter polymerization tank was a horizontal stirring tank which did not have a rectification column, and a jacket was attached to the whole.

Melt polycondensation was carried out under the following operating conditions. As the aromatic dihydroxy compound, bisphenol A pneumatically transported as described above and stored in the second hopper was used, and diphenyl carbonate in a molten state 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 mixed and stirred with stirring.

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

While the raw material was continuously supplied to the initial polymerization tank, the catalyst solution was supplied so that the disodium salt of bisphenol A was 1 μ equivalent per 1 mol of bisphenol A in the raw material to carry out continuous melt polycondensation.

The operating conditions of each polymerization tank were as follows: the initial polymerization tank had an internal temperature of 250 ° C. and a vacuum degree of 4 KPa (30 Torr), the latter polymerization tank had a temperature of 270 ° C. and a vacuum degree of 67 Pa (0.5 Torr).
Met.

The operating time was 600 hours continuously. Samples of polycarbonate were sampled at the exit of the late polymerization tank at a frequency of once / 100 hours, and quality was evaluated. The results are shown in Table 1.
It was shown to. Further, the transfer of bisphenol A from the second hopper to the monomer mixture adjusting tank can be stably operated throughout the operation period, and the bisphenol A adhered to the transfer pipe was slight even in the inspection after the operation was completed.

[Comparative Example 1] In the apparatus of Example 1, the mixing ratio of bisphenol A and nitrogen in pneumatic transport was 2, and the wind speed of nitrogen was at the mixing portion of the aromatic dihydroxy compound (first hopper outlet). 45m / S
And

The oxygen concentration of nitrogen, which is a transport medium for pneumatic transport, is 5.0%, the dew point is 0 ° C.,
The foreign matter content of 0.5 μm or more was 28,500 particles / m ³ .

Using the above method, the same bisphenol A as in Example 1 was pneumatically transported from the first hopper to the second hopper. As a result, the angle of repose was 55 ° and the charge amount was 250.
A powdery bisphenol A of k volts was obtained.

Continuous operation was carried out for 600 hours under the same apparatus and operating conditions as in Example 1 except that the aromatic dihydroxy compound was used.

Polycarbonate sample is 1 time / 1
Samples were collected at the exit of the latter-stage polymerization tank at a frequency of 00 hours, and the quality was evaluated. The results are shown in Table 1.

The transfer of bisphenol A from the second hopper to the monomer mixture adjusting tank was unstable, and intermittent transfer occurred. Further, the transfer pipe was frequently blocked, and daily inspection and cleaning were indispensable.

[0097]

[Table 1]

[0098]

[Effects of the Invention] An increase in the angle of repose of an aromatic dihydroxy compound in pipe transportation is suppressed to a certain value or less, the amount of charge is suppressed to a certain value or less, the velocity of an inert gas as a transportation medium, and a raw material to be transported. By controlling the ratio with the ratio within a specific numerical range, the adhesion of the raw materials on the transfer pipe is reduced, the molar balance control is facilitated, and a polycarbonate of excellent quality can be efficiently produced.

   ─────────────────────────────────────────────────── ─── 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 AC01 BB03A                       BB04A BB05A BB08A BB09A                       BB10A BB11A BB12A BB13A                       HC02 HC03 HC04 HC05 JA091                       JA121 JA161 JA201 JA301                       JB171 JC021 JC091 JF021                       JF031 JF041 JF141 JF151                       JF161 KA00 KB11 KE02                       KE05 LB01

Claims (7)

[Claims] 1. A carbon dioxide diester and a pneumatically-transported powdery aromatic dihydroxy compound, wherein the molar ratio of the aromatic dihydroxy compound to the carbonic acid diester is 1.
In a method of producing an aromatic polycarbonate by mixing and dissolving while maintaining a fluctuation range of ± 0.005 or less in the range of 1.00 to 1.10, then melt polycondensation in the presence of a transesterification catalyst, An aromatic dihydroxy compound having an angle of repose of 10 ° or less after pneumatically transporting an aromatic dihydroxy compound having a repose angle of 35 ° to 50 ° and having a flake or prill shape is used. Method for producing polycarbonate. 2. The carbonic acid diester and the pneumatically transported powdery aromatic dihydroxy compound are mixed at a molar ratio of the aromatic dihydroxy compound to the carbonic acid diester of 1
In a method of producing an aromatic polycarbonate by mixing and dissolving while maintaining a fluctuation range of ± 0.005 or less in the range of 1.00 to 1.10, then melt polycondensation in the presence of a transesterification catalyst, A method for producing an aromatic polycarbonate, characterized in that an aromatic dihydroxy compound having a charge amount after pneumatic transfer of 100 kV or less is used as the powdery aromatic dihydroxy compound. 3. The velocity of an aromatic dihydroxy compound in a pipe for pneumatically transporting a powdered aromatic dihydroxy compound is A (kg / hr), and the velocity of an inert gas as a transport medium is B (kg / hr). When the above formula (1) is satisfied, an aromatic dihydroxy compound pneumatically transported under the condition that the following formula (1) 15 ≧ A / B ≧ 3 (1) is established is used. A method for producing an aromatic polycarbonate. 4. The wind velocity of an inert gas, which is a transport medium for pneumatically transporting the powdery aromatic dihydroxy compound, is 1 at the mixing portion of the aromatic dihydroxy compound.
It is 0 m / S or more and 40 m / S or less, The manufacturing method of the aromatic polycarbonate as described in any one of Claims 1-3 characterized by the above-mentioned. 5. The dew point of an inert gas, which is a transport medium for pneumatically transporting a powdered aromatic dihydroxy compound, is -1 ° C. or lower.
5. The method for producing an aromatic polycarbonate according to any one of 4 above. 6. The oxygen concentration in an inert gas, which is a transport medium for pneumatically transporting a powdered aromatic dihydroxy compound, is set to 3% or less. 2. The method for producing an aromatic polycarbonate according to item 1. 7. The content of foreign matter of 0.5 μm or more in an inert gas, which is a transport medium for pneumatically transporting a powdered aromatic dihydroxy compound, is 10,000 / m ³ or less. Item 7. A method for producing an aromatic polycarbonate according to any one of Items 1 to 6.