JPH0948844A - Production of polycarbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject polymer good in thermal stability on the melting of the polymer and especially stable in the quality on the melt-molding of the polymer by a two phase interfacial polycondensation method comprising emulsifying an organic phase with an aqueous phase containing a diphenol alkali metal salt and subsequently introducing phosgene into the emulsion. SOLUTION: An organic phase containing an inactive organic solvent (preferably methylene dichloride) capable of dissolving the reaction product but not dissolving water is brought into contact with an aqueous phase containing water, diphenol [preferably 2,2-bis-(4-hydroxyphenyl)propane[ and an alkali metal hydroxide under an emulsification condition. The obtained emulsion is brought into contact with phosgene under condensation polymerization conditions and under a weaker mixing condition than that of the emulsification condition to obtain the objective polymer. The emulsification of the aqueous phase with the organic phase is preferably performed under a condition comprising a Weber number We of >=3.5×10<4> , and the contact of the emulsion with the phosgene is also preferably performed under a mixing condition comprising a Weber number of 1 to 2×10<3> . The phosgene is preferably introduced by a piston flow method.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polycarbonate, and more particularly to a method for producing a thermoplastic aromatic polycarbonate by a two-phase interfacial polycondensation method.
More particularly, it relates to a method for producing an oligomer which gives a polycarbonate having good thermal stability when melted, and particularly stable quality when melt-molded.

[0002]

2. Description of the Related Art Conventionally, a technique of a two-phase interfacial condensation method for obtaining a polycarbonate oligomer in the presence of an organic solvent by reacting an aqueous solution of an alkali metal salt of diphenol with phosgene is known. Many improved techniques have been proposed which regulate the mixing and emulsification of the organic phase and the aqueous phase during the reaction.

For example, in JP-A-47-14297 and JP-A-62-167321, a method of mixing with a static mixer at the time of introducing phosgene in the phosgenation step is disclosed in JP-A-1-90220 or European Patent No. 472848 discloses a method of defining the molecular weight of the resulting oligomer upon mixing with phosgene using a static mixer, and defining the amount of condensation catalyst added in the same step, etc. Various proposals have been made regarding the mixed state of phosgene with an organic phase and an aqueous phase in the phosgenation step. In recent years, by changing the ratio of organic phase to aqueous phase,
A method of changing the form of the produced emulsion and mixing them has also been proposed (see JP-A-6-100685).

However, all of them have been proposed for the mixed state in the coexistence of phosgene, and do not relate to the mixing of an organic phase without phosgene and an aqueous phase. Therefore, the organic phase and the aqueous phase do not necessarily give good heat-stable polymers, as they are fed in poorly mixed at the inlet to the phosgenation process. Furthermore, since phosgene, the organic phase and the aqueous phase are mixed and emulsified simultaneously, the dissolution of phosgene in the organic phase is accelerated, resulting in poor thermal stability. Further, when the renewal of the interface is extremely vigorous (when the emulsification is extremely advanced), the decomposition rate of phosgene is high and the raw material loss is large and disadvantageous.

On the other hand, Japanese Patent Publication No. 37-2198 and Japanese Patent Publication 5
In JP-A No. 2-36554, a proposal including a fine regulation such as making the droplets of the emulsion liquid fine is made, but in all cases, polycarbonate production conditions in the polycondensation step after the phosgenation step (oligomer formation step) This is because the main factor of thermal stability has already been determined at this stage, and there is little room for improvement.

[0006]

SUMMARY OF THE INVENTION The present inventors have made earnest studies on the thermal stability of the polycarbonate obtained as the final product when melted, especially the color tone during melt molding, and as a result, surprisingly, this thermal stability was confirmed. The factors that control most of the sex are
It was found to be due to the oligomers that were obtained in the phosgenation step, and what was produced in the very first few seconds, where most of the phosgene was consumed.

That is, in the two-phase interfacial condensation method, the phosgenation reaction is generally carried out by bringing phosgene dissolved in an inert organic solvent in an organic phase into contact with an alkali metal salt of diphenol in an aqueous phase to effect a chloroformate reaction. To obtain a terminal oligomer, when dissolution of phosgene in the organic phase and emulsification of the organic phase and the aqueous phase proceed simultaneously, the reaction in the organic phase becomes predominant and the chloroformate is introduced at one end. Oligomer immediately transforms into a bischloroformate. From such a bischloroformate oligomer, it is difficult to obtain a polycarbonate having good thermal stability.

[0008]

On the other hand, when an emulsion in which an organic phase and an aqueous phase are emulsified and the interfacial area is previously increased is brought into contact with phosgene, an oligomer formed at the interface is diphenol from the aqueous phase. Since the supply of the alkali metal salt is sufficient, the production of monochloroformate becomes dominant.
In order to obtain oligomers with good thermal stability, it is ideally preferable to avoid the dissolution of phosgene in the organic phase. As a condition therefor, the contact reaction with the initial phosgene is regulated, that is, after emulsifying the organic phase and the aqueous phase, a method of introducing phosgene into the emulsion is an addition reaction compared to the dissolution of phosgene in the organic phase. As a result, it is known that the resulting monochloroformate body can be most predominantly produced, and the resulting melt heat stability of the polycarbonate, particularly the color tone at the time of melt molding, is the best. Completed the invention.

That is, the object of the present invention is to provide a method for producing a polycarbonate resin having a great industrial value, and the gist of the present invention is to use a two-phase interfacial condensation method in accordance with a diphase in an aqueous phase. A method for producing a polycarbonate, which comprises reacting an alkali metal salt of phenol with phosgene in an organic phase to obtain an oligomer,
The reaction product dissolves, but an organic phase containing an inert organic solvent that does not dissolve water, and an aqueous phase containing water, diphenol and an alkali metal hydroxide are contacted under emulsification conditions to form an emulsion. And (2) contacting this emulsion with phosgene under a condensation reaction condition and a mixing condition weaker than the above emulsification conditions to obtain an oligomer. On the way.

[0010]

1 and 2 are flow charts showing an embodiment of the method of the present invention. In the figure, 1 is a homomixer, 2 and 3 are pipes, 4 is a supply pipe for raw material bisphenol A, NaOH aqueous solution, water, etc., 5 is a supply pipe for methylene chloride, 6 is a pump, 7 is a supply pipe for phosgene, and 8 is A pipe reactor, 9 is a tank reactor, and 10 is a refrigerator.

The aqueous phase to be emulsified in the process of the present invention must contain at least three components: water, diphenol and alkali metal hydroxide. In the aqueous phase, diphenols react with alkali metal hydroxides such as sodium hydroxide or potassium hydroxide to yield water soluble alkali metal salts. Of course, it is preferable to mix the above three components to prepare a uniform aqueous solution and prepare the aqueous phase before contacting with the organic phase, but if necessary, a part of these three components or It is also possible to mix all upon contact with the organic phase. The molar ratio of diphenol to alkali in the aqueous phase is 1: 1.8 to 1: 3.5.
Is preferable, and more preferably 1: 2.0 to 1: 3.2. When preparing such an aqueous solution, the temperature should be 20 ° C.
As described above, it is preferable to set the temperature to 30 to 40 ° C., but if it is too high, the oxidation of diphenol occurs, so the temperature is set to the minimum required temperature and the nitrogen atmosphere is used,
It is preferable to add a small amount of a reducing agent such as hydrosulfite.

The diphenols used in the present invention preferably correspond to the general formula HO-Z-OH.
Here, Z is one or more aromatic nuclei and the hydrogen bonded to the carbon of the nuclei can be replaced by chlorine, bromine, an aliphatic group or an alicyclic group. Multiple aromatic nuclei
It is also possible to have different substituents. Also,
A plurality of aromatic nuclei may be linked by a bridging group. The bridging group includes aliphatic groups, cycloaliphatic groups, heteroatoms or combinations thereof.

Specifically, hydroquinone, resorcin,
Dihydroxydiphenol, bis- (hydroxyphenyl) -alkane, bis- (hydroxyphenyl) -cycloalkane, bis- (hydroxyphenyl) -sulfide, bis- (hydroxyphenyl) -ether, bis-
(Hydroxyphenyl) -ketone, bis- (hydroxyphenyl) -flufone, bis- (hydroxyphenyl) -sulfoxide, bis- (hydroxyphenyl)
-Dialkylbenzenes, and their derivatives with alkyl or halogen substituents in the nucleus. Of course, it is also possible to use two or more of these diphenols together.

These diphenols and other suitable diphenols are described, for example, in US Pat. No. 4,982,014,
No. 3,028,365, No. 2,999,835
No. 3, No. 3,148,172, No. 3,275,60
No. 1, No. 2,991,273, No. 3,271,3
No. 67, No. 3,062, 781, 2, 970, 13
No. 1, and No. 2,999,846, German Patent Publication No. 1,570,703, and No. 2,063,0.
50, No. 2,063,052, and No. 2,21
No. 1,956, and French Patent No. 1,56
No. 1,518.

Particularly preferred diphenols are 2,2-bis- (4-hydroxyphenyl) -propane, 2,2-
Bis- (3,5-dimethyl-4-hydroxyphenyl)
-Propane, 1,1-bis- (4-hydroxyphenyl) -cyclohexane and 1,1-bis- (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane.

The organic phase to be emulsified in the present invention is
At the reaction temperature and pressure, the reaction products such as phosgene and carbonate oligomer, polycarbonate, etc. dissolve, but it does not dissolve water (in the sense that it does not form a solution with water) It is necessary to include any inert organic solvent Is.

Typical inert organic solvents include aliphatic hydrocarbons such as hexane and n-heptane, methylene chloride, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, tetrachloroethane, dichloropropane and 1,2-dichloroethylene. Such as chlorinated aliphatic hydrocarbons, benzene, aromatic hydrocarbons such as toluene and xylene, chlorobenzene, chlorinated aromatic hydrocarbons such as o-dichlorobenzene and chlorotoluene, and other substitutions such as nitrobenzene and acetophenone Aromatic hydrocarbons are included. Among them, chlorinated hydrocarbons such as methylene chloride or chlorobenzene are preferably used. These inert organic solvents can be used alone or as a mixture with other solvents.

However, when chlorobenzene is used alone, it is necessary to use high operating temperatures during the reaction and washing in order to obtain a technically useful concentration of the polycarbonate in chlorobenzene. Also, 2,2-
A suitable solvent combination for industrially important polycarbonates based on bis- (4-hydroxyphenyl) -propane is a mixture of methylene chloride and toluene, if necessary also according to the process of the invention. Can be used.

In the present invention, it is necessary to bring the organic phase and the aqueous phase into contact with each other to form an emulsion prior to the contact with phosgene. The mixer used for this purpose is It is a dynamic mixer or a static mixer capable of realizing desired emulsification conditions. In the case of a static mixer, a simple orifice or a reaction tube filled with glass spheres, Raschig rings, etc. is insufficient to realize desired emulsification conditions and cannot be used as a static mixer. Therefore, the static mixer referred to here is a static mixer having no moving parts, that is, a static mixer having no stirrer as compared with a mixer having a stirrer, and more specifically, a static mixer fixed in a pipe. A mixing device which mixes a solution by dividing a flow by means of a mixing element having no parts and changing or reversing the flow direction and repeating division / conversion / reversal of the flow in the vertical and horizontal directions. With a static mixer like this,
It is also possible to secure the required linear velocity and realize desired emulsification conditions.

On the other hand, in the dynamic mixer, a normal paddle,
It is not impossible to use a simple stirrer having a propeller, a turbine, a chi-type stirring blade, etc., and increase the number of revolutions for emulsification. However, in the present invention, as a device for obtaining a desired emulsified state, a high speed stirrer such as a homogenizer or a homomixer, a colloid mill, a flow jet mixer or an ultrasonic emulsifier is suitable. The use of these is particularly effective because a highly emulsified state having a finer droplet diameter can be obtained as compared with the emulsified state obtained by a simple stirrer. These dynamic mixers and static mixers can also be used in combination. Mixing is performed at 5 to 50 ° C, preferably 0 to 30 ° C.

Such a good emulsified state can be usually expressed by the Weber number We or P / q described later. The Weber number We is a dimensionless number that expresses the degree of droplet dispersion, and is usually 1 × 10 ⁴ or more, preferably 2 × 10 ⁴ or more, and more preferably 3.5 × 10 ⁴ or more. The Weber number can be obtained by various methods, and when a dynamic mixer is used, it can be obtained by the following equation.

[Formula 2] We = ρ · n ² · d ³ / σ where ρ is the specific gravity of the emulsion in the system (kg / m ³ ), n is the rotation speed (rps) of the stirrer, and d is the stirrer. Blade diameter (m), σ
Represents the interfacial tension (N / m) between the aqueous phase and the organic phase in the system, respectively.

When a static mixer is used, the Weber number can be calculated by the following equation.

[Equation 3] We = ρ · V ² · dh / (ε ² · σ) where ρ is the specific gravity of the emulsion in the system (kg / m ³ ), and V is the empty pipe of the emulsion in the system. Standard linear velocity (m / sec),
dh is the equivalent fluid diameter (m) of the mixer, σ is the interfacial tension (N / m) between the aqueous phase and organic phase in the system, and ε is the porosity.

On the other hand, P / q expressing the emulsified state is usually 200 kg · m / l or more, preferably 500 kg · m.
/ L or more, more preferably 1000 kg · m / l or more and expressed by the following formula.

[Number 1] P / q = Np · ρ · n 3 · d 5 / (g · q) where, Np is a constant, a bath-type mixer 0.8, and 2.31 in a tubular mixer. ρ is the specific gravity of the emulsion in the system (kg / m ³ ), n is the number of revolutions of the stirrer (rps), d is the blade diameter of the stirrer (m), and g is the acceleration of gravity (m / se).
c ² ) and q represent the flow rate (l / sec) of the emulsion in the system, respectively.

If the emulsification is insufficient, it is difficult to obtain a polycarbonate having good heat stability. Further, even if the emulsification is performed more than necessary, the remarkable improvement effect is difficult to be recognized. Therefore, it is usually expressed by the Weber number and about 1 × 10 ⁶ or less is sufficient. In the present invention, the preferred emulsion is
It has a droplet diameter of 0.01 to 10 μm and has emulsion stability.

In the present invention, the emulsion thus obtained is contacted with phosgene under condensation reaction conditions,
It is necessary to obtain an oligomer consisting mainly of monochloroformate. Thus, in the present invention, before contact with phosgene, if the organic phase and the aqueous phase have reached the aforementioned emulsified state, during contact with phosgene, as described above, preferentially and for a short time. Therefore, it is not necessary to use a special stirring means since a monochloroformate oligomer is produced. Rather, if the mixed state during contact with phosgene is unnecessarily high, dissolution of phosgene in the organic phase is accelerated, and it becomes difficult to obtain a polycarbonate having good thermal stability.
Therefore, in the present invention, it is necessary to carry out the contact with phosgene under a mixing condition weaker than the emulsifying condition at the time of the contact between the organic phase and the aqueous phase.

Here, the mixing conditions weaker than the emulsification conditions are:
For example, it can be evaluated by the above-mentioned Weber number We or P / q. For example, when evaluated by the Weber number We, it is usually less than 1 × 10 ⁴ , preferably 5 × 10 ³ or less,
More preferably 2 × 10 ³ or less, most preferably 1 to 3
A mixing condition of 2 × 10 ³ is adopted. When evaluated by P / q, it is usually less than 200 kg · m / l, preferably 10
Less than 0 kg · m / l, more preferably 50 kg · m /
Adopt mixing conditions of less than 1. Excessive mixing will accelerate the dissolution of phosgene in the organic phase. The lower limit of the degree of mixing is not particularly limited, but it is usually 1 × Weber number We.
It is 10 ³ or more and about 5 kg · m / l or more in P / q.

The method of contacting with phosgene is not particularly limited as long as the above conditions are satisfied, and examples thereof include a method of introducing phosgene into a tubular reactor or a tank reactor.
Further, a loop type reactor may be provided by providing a loop in these reactors. Generally, in the case of a tank type reactor, since the inside of the tank is in a stirring state, the above mixing conditions may not be satisfied in some cases. Preferably, a tubular reactor is used. Also,
The contact with phosgene is preferably performed by a piston flow method. In the case of the piston flow method, it is easy to satisfy the above mixing conditions. In the case of a tubular reactor, the degree of flow at a linear velocity of about 1.0 m / sec or more,
In the case of a tank reactor, if the above mixing conditions are satisfied by the combination of the rotation speed and blade diameter of the stirrer (paddle) installed in the reactor, the emulsified state required for condensation can be maintained. Is quite possible.

Oligomerization proceeds by contact with phosgene. At this time, until the alkali metal salt of diphenol in the aqueous phase disappears, the emulsion prepared before contact with phosgene has a certain emulsion. It is preferable to maintain the state. That is, it is preferable to maintain the above mixing conditions until the alkali metal salt of diphenol in the aqueous phase disappears.
For example, the Weber number We is set to 1 × 10 ³ to 1 × 10 ⁴ until the alkali metal salt of diphenol in the aqueous phase disappears.
It is preferable to keep the above P / q at 5 to 50 kg · m / l.

Of course, the initial stage of the condensation reaction for obtaining mainly the monochloroformate oligomer and the latter stage for eliminating the alkali metal salt of diphenol are
It is also possible to work in a separate reactor. For example, the reaction can be carried out in a piston flow type reactor in the early stage because the reaction rate is sufficiently high, and in a complete mixing type reactor in which the required residence time is easily obtained in the latter stage. . As in the present invention, when the methylene chloride organic phase and the aqueous phase of the alkali metal salt of diphenol form an emulsion,
High-concentration phosgenation is possible, and a product with good thermal stability can be obtained.

The reaction temperature for obtaining the oligomer is 80
℃ or less, preferably 60 ℃ or less, more preferably 10
It is preferably in the range of 50 ° C to 50 ° C. Too high,
Side reactions cannot be suppressed, and the phosgene basic unit deteriorates. On the other hand, if it is too low, it is a preferable situation in terms of reaction control, but the refrigeration load increases, and the cost increases correspondingly, which is not preferable.

Phosgene is used in liquid or gaseous form. From the viewpoint of temperature control, phosgene is preferably liquid, and a reaction pressure capable of maintaining liquid at the reaction temperature is selected. The preferred amount of phosgene used depends on the reaction conditions, in particular the reaction temperature and the concentration of the diphenol alkali metal salt in the aqueous phase, but
The number of moles of phosgene relative to the moles is usually 1 to 2, preferably 1 to 1.5. If this ratio is too large, the loss of phosgene increases, which is not preferable. If this ratio is too small, CO groups will be insufficient and appropriate molecular weight extension will not be carried out, which is not preferable.

The concentration of the oligomer in the organic phase at the stage of obtaining the oligomer may be in the range in which the obtained oligomer is soluble, and specifically, it is about 10 to 40% by weight. Further, the ratio of the organic phase is preferably 0.2 to 1.0 in volume ratio with respect to the aqueous solution of the alkali metal hydroxide of diphenol, that is, the aqueous phase. The viscosity average molecular weight (Mv) of the oligomer obtained under such condensation conditions is usually about 500 to 10,000, preferably 1,000 to.
It is 5,500.

The oligomer thus obtained is converted into a polymeric polycarbonate under polycondensation conditions according to a conventional method. In a preferred embodiment, the organic phase in which the oligomer is dissolved is separated from the aqueous phase, and if necessary, the above-mentioned inert organic solvent is added to adjust the concentration of the oligomer. That is, in the organic phase obtained by polycondensation,
The amount of the solvent is adjusted so that the concentration of the polycarbonate is 5 to 30% by weight. Thereafter, a new aqueous phase containing water and an alkali metal hydroxide is newly added, and in order to further adjust the polycondensation conditions, preferably a condensation catalyst described below is added, and a desired two-phase interfacial condensation method is followed according to the desired polycondensation method. Complete the condensation. The ratio of the organic phase and the aqueous phase at the time of polycondensation is preferably a volume ratio of organic phase: aqueous phase = 1: 0.2 to 1.

In the present invention, the polycondensation reaction can be carried out in the presence of any chain terminator and / or branching agent. Suitable chain terminators include various monophenols,
For example, in addition to ordinary phenol, C1-C10 alkylphenols such as pt-butylphenol and p-cresol, and p-chlorophenol and 2,
Halogenated phenols such as 4,6-tribromophenol are included. Of these, phenol, cumylphenol, isooctylphenol and pt-butylphenol are suitable chain terminators. The amount of the chain stopper used varies depending on the molecular weight of the desired condensate, but is usually 0.5 with respect to the amount of diphenol in the aqueous phase.
It is used in an amount of from 10 to 10% by weight.

The branching agent used can be chosen from various compounds having three or more functional groups.
Suitable branching agents include 2,4-bis-, which is a compound having three or more phenolic hydroxyl groups.
(4-Hydroxyphenyl-isopropyl) -phenol, 2,6-bis- (2'-hydroxy-5'-methylbenzyl) -4-methylphenol, 2- (4-hydroxyphenyl) -2- (2,4) -Hydroxyphenyl)
-Propane and 1,4-bis- (4,4'-dihydroxytriphenylmethyl) -benzene. Also,
A compound having three functional groups, 2,4-dihydroxybenzoic acid, trimesic acid, cyanuric chloride, bis-
Also included are (4-hydroxyphenyl) -2-oxo-2,3-dihydroxyindole and 3,3-bis- (4-hydroxy-3-methylphenyl) -2-oxo-2,3-dihydroindole. Among them, those having three or more phenolic hydroxy groups are preferred. Although the amount of the branching agent used varies depending on the desired degree of branching, it is usually 0.
It is used in an amount of 05-2 mol%.

The polycondensation reaction can be carried out in the presence of a condensation catalyst. The condensation catalyst can be arbitrarily selected from many condensation catalysts used in the two-phase interfacial condensation method. Among them, trialkylamine, N-ethylpyrrolidone, N-ethylpiperidine, N-ethylmorpholine, N-isopropylpiperidine and N-isopropylmorpholine are particularly suitable, and particularly triethylamine and N-ethylpiperidine are extremely suitable. When adding the above chain terminator, branching agent and condensation catalyst,
The addition timing is not particularly limited, and it may be added to the polycondensation reaction system, at the time of contact with phosgene which is the preceding step, or at the time of forming an emulsion.

After the completion of the polycondensation, a washing treatment is carried out with an alkali such as NaOH until the residual chloroformate group becomes 0.1 μeq / g or less. After that, the organic phase is washed until the electrolyte is exhausted, and finally the inert organic solvent is appropriately removed from the organic phase to separate the polycarbonate.
The viscosity average molecular weight (Mv) of the polycarbonate thus obtained is usually about 10,000 to 100,000, preferably about 12,000 to 35,000.

In the present specification, the average molecular weight (M
v) means the following two formulas from the specific viscosity (ηsp) measured at a temperature of 20 ° C. using a concentration of oligomer or polycarbonate (C) of 0.6 g / dl methylene chloride solution.

[Equation 4] ηsp / C = [η] (1 + 0.28ηsp) [η] = 1.23 × 10 ⁻⁵ A value calculated using Mv ^0.83 .

The polycarbonate obtained by the process of the present invention contains various additives such as a stabilizer, a die-cutting agent, a flame retardant, a charge, during the separation thereof from the reactor, or before or during the processing thereof. Effective amounts of inhibitors, fillers, fibers, impact strength modifiers and the like can be added.

These polycarbonates are injection molded,
Various molded products such as films by extrusion molding, etc.
It can also be processed into threads, boards, etc. and in various technical fields, for example in the electrical component or construction industry, and also for luminaire materials and optical equipment materials, especially lamp housings, optical lenses, optical disks and audio disks. Used for etc.

[0041]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these as long as the gist thereof is not exceeded.

The symbols or abbreviations used in the examples have the following meanings. Symbol or abbreviation Meaning BPA Bisphenol A BPA-Na Bisphenol A sodium salt NaOH Sodium hydroxide N ₂ Nitrogen

Examples 1 to 6 Bisphenol A 15.09 kg / hour, NaOH
5.49 kg / hour and 93.5 kg / hour of water were dissolved at 35 ° C. in the presence of 0.017 kg / hour of hydrosulfite, and then cooled to 5 ° C. and methylene chloride 61 cooled to 5 ° C. An organic phase of 9 kg / hour was supplied to each stainless steel pipe having an inner diameter of 6 mm and an outer diameter of 8 mm, mixed in the same pipe, and further homomixer (manufactured by Tokushu Kika Co., Ltd., product name TK homomic line mill). SL-6 type) was used to emulsify at a rotation speed of 6000 rpm to prepare an emulsion.

As shown in FIG. 1, the emulsification and mixing are carried out by connecting the inlet side 2 and the outlet side 3 of the homomixer 1 with the stainless steel pipe, and a loop for circulating the emulsion prepared by the mixer. It was formed by pushing the aqueous phase 4 and the organic phase 5 into the mixer with a centrifugal pump 6 from before the mixer inlet side connecting portion. In Examples 1 to 4, the degree of emulsification was changed by changing the number of passes in the mixer. In Examples 5 and 6, the same number of passes as in Example 1 was adopted.

The emulsion of the BPA-Na aqueous solution (aqueous phase) and methylene chloride (organic phase) thus obtained was taken out through a pipe having an inner diameter of 6 mm and an outer diameter of 8 mm branching from the loop. In a pipe reactor having an inner diameter of 6 mm and a length of 34 m to be connected, 7.2 kg of liquefied phosgene supplied from a pipe 7 which was separately introduced here and cooled to 5 ° C.
/ Hour. 1.7m inside the pipe reactor 8
The oligomerization reaction was carried out while flowing at a linear velocity of / sec for 20 seconds. At this time, the reaction temperature reached 35 ° C. in the heat insulating systems of Examples 1 to 4. In Examples 5 and 6, external cooling was performed so that the reaction temperatures were 30 ° C. and 25 ° C., respectively. At the time of oligomerization, 0.005 kg / hour of catalyst triethylamine and 0.3 kg / hour of pt-butylphenol as a molecular weight regulator were introduced before the homomixer inlet side connecting portion.

The oligomerized emulsion thus obtained from the pipe reactor is further introduced into a reaction vessel 9 with an agitator having an internal volume of 50 liters, and the mixture is stirred under N ₂ atmosphere for 30 times.
After the unreacted BPA-Na existing in the aqueous phase was completely consumed by stirring at 0 ° C. and oligomerizing, the aqueous phase and the oil phase were allowed to stand and separate to obtain a methylene chloride solution of the oligomer. .

From the methylene chloride solution of the above oligomer, 23 kg was charged into a reaction tank having an internal volume of 70 L and equipped with a Faudler blade, and 10 k of diluting methylene chloride was added thereto.
g was added, and further 25 wt% NaOH aqueous solution 2.2 k was added.
g, 6 kg of water and 2.2 g of triethylamine were added, and N
_The mixture was stirred at 30 ° C. in ₂ atmospheres and a polycondensation reaction was performed for 60 minutes to obtain a polycarbonate.

To this reaction solution, 30 kg of methylene chloride and 7 kg of water were added, and after stirring for 20 minutes, the stirring was stopped,
The aqueous and organic phases were separated. 0.1N to the separated organic phase
After adding 20 kg of hydrochloric acid and stirring for 15 minutes to extract triethylamine and a small amount of remaining alkaline component, the stirring was stopped and the aqueous phase and the organic phase were separated. Further, 20 kg of pure water was added to the separated organic phase, and after stirring for 15 minutes, the stirring was stopped and the aqueous phase and the organic phase were separated. This operation was repeated (3 times) until chlorine ions in the extracted waste water were not detected. The obtained purified polycarbonate solution was pulverized with a kneader and dried to obtain granular powder (flakes). The nitrogen content in the flake was 1.5 ppm.

The average molecular weight of the oligomer obtained in each Example, the average molecular weight and the molecular weight distribution of the flakes, and the color tone of the molded article were measured. Table 1 shows the results.

The physical properties of the polycarbonates in each table were evaluated as follows. 1) Molecular weight distribution (Mw / Mn): using a GPC device (manufactured by Toso Co., Ltd., product name HLC-8020) and using tetrahydrofuran (THF) as an eluent, four types of high-speed GPC
Filling material (product of Toso Corporation, product name TSK 5000H
LX, 4000HLX, 3000HLX and 2000H
(LX) was separated by four columns packed, and Mw and Mn were calculated in terms of polystyrene from the chart obtained by detecting the difference in refractive index, and Mw / Mn was calculated.

2) Color tone (YI): [Molding of sample plate] The flakes were plasticized at 280 ° C using an injection molding machine (manufactured by Nisshin Jushi Kogyo Co., Ltd., product name FS80S-12ASE), and then in a cylinder. After being retained for 15 seconds, a sample plate having a thickness of 3.2 mm and a size of 60 mm square was formed.
Also, a sample plate was formed after the plasticization so that the residence time in the cylinder was 5 minutes. [Measurement of Color Tone] For these sample plates, a color difference meter (manufactured by Suga Test Instruments Co., Ltd., product name SM-4-CH) was used.
The color tone (YI value) was measured. Of the measured values, a small YI value for 15 seconds retention indicates that the color tone during steady molding is good, and the difference between the 15 seconds and 5 minutes retention YI values (ΔY
The fact that I) is small indicates that the thermal stability at high temperatures is good.

[0052]

[Table 1]

Comparative Example 1 In Example 1, an aqueous solution of bisphenol A in NaOH and ethylene chloride were mixed by passing through an orifice having an inner diameter of 2 mm instead of using a homomixer and a loop containing the same, and then contacting with phosgene. The same operation as in Example 1 was performed except that the reaction was performed.

Example 7 In Example 1, the catalyst triethylamine and the molecular weight modifier pt-butylphenol were added to a reaction vessel equipped with a Faudler blade having an internal volume of 70 liters, without being introduced in front of the connection part on the inlet side of the homomixer. Except for this, the same operation as in Example 1 was performed.

Comparative Example 2 The same operation as in Example 4 was carried out except that, in Example 4, not only the NaOH aqueous solution of bisphenol A and methylene chloride but also phosgene were introduced into a loop containing a homomixer. went.

Also in Comparative Examples 1 and 2 and Example 7, as in Examples 1 to 6, the obtained oligomers were analyzed for the average molecular weight, for flakes, the average molecular weight and the molecular weight distribution, and for the molded articles. , And the color tone was measured. The results are shown in Table 2.

[0057]

[Table 2]

Examples 8 to 12 These examples were carried out according to the flow chart shown in FIG. Bisphenol A 16.31 kg / hr, NaOH
5.93 kg / hr and 101.1 kg / hr of water, in the presence of 0.013 kg / hr of hydrosulfite, 35
After melting at ℃, cooled to 5 ℃, and cooled to 5 ℃, and the methylene chloride 68.0 kg / h organic phase was fed to stainless steel pipes with inner diameter of 6 mm and outer diameter of 8 mm, respectively, and mixed in the same pipe. Homo mixer (manufactured by Tokushu Kika Co., Ltd., product name TK homomic line flow LF-50)
(Type 0) was used to emulsify to prepare an emulsion. At this time, the interfacial tension between methylene chloride and water was set to 40 mN / m. In Examples 8 to 10, the degree of emulsification was changed by changing the rotation speed of the homomixer. In Examples 11 and 12, higher rotational speeds were selected.

The emulsion of the BPA-Na aqueous solution (aqueous phase) and methylene chloride (organic phase) thus obtained is branched from the homomixer 1 to have an inner diameter of 6 mm and an outer diameter of 8 mm.
6mm inner diameter, length 34
In a Teflon-made pipe reactor 8 of m, it was contacted with liquefied phosgene 7.5 kg / hour supplied from a pipe 7 separately cooled here at 5 ° C. The oligomerization reaction was carried out while flowing through the pipe reactor 8 at a linear velocity of 1.7 m / sec for 20 seconds. At this time, the reaction temperature reached 45 ° C. in the heat insulating systems of Examples 8 to 10. In Examples 11 and 12, the liquid temperature of the raw materials was adjusted so that the reaction temperatures were 60 ° C. and 70 ° C., respectively, and external cooling was performed to 35 ° C. before entering the next oligomerization tank 9. Upon the oligomerization, the catalyst triethylamine 0.0
05 kg / hour and 0.65 kg / hour of pt-butylphenol, which is a molecular weight regulator, are each used in the oligomerization tank 9 described above.
Introduced.

Thereafter, by the same method as in Examples 1 to 6,
Oligomerization, polycondensation, washing, drying and molding were performed. The results are shown in Table 3.

Comparative Example 3 The same amount of BPA-N as in Example 8 was used without passing through a homomixer.
a 7.5 kg of liquefied phosgene supplied from an aqueous solution (aqueous phase) and methylene chloride (organic phase) through a pipe cooled to 5 ° C
The same procedure as in Example 8 was carried out except that the contact time was / hour. The results are also shown in Table 3.

[0062]

[Table 3]

[0063]

The polycarbonate obtained by the present invention usually has an average molecular weight of 10,000 to 100,000, and the molded product has not only the excellent physical properties peculiar to polycarbonate, but also the thermal stability in high temperature molding. Is significantly improved, and a molded product with less coloring can be obtained, which has the advantage that the range of applications can be greatly expanded compared to conventional products.

According to the present invention, it is possible to obtain a polycarbonate having an excellent hue and a small change in hue after melt molding. Moreover, since the emulsification of the organic phase and the aqueous phase and the reaction by contact with phosgene can be performed as separate steps, the decomposition rate of phosgene can be suppressed. Furthermore, since the reaction can be performed at a relatively high temperature as compared with the conventional methods, the load on the refrigerator can be reduced.

[Brief description of drawings]

FIG. 1 is a flow chart showing an embodiment of a method of the present invention.

FIG. 2 is a flow chart showing another embodiment of the method of the present invention.

[Explanation of symbols]

1 homomixer 2, 3 pipes, 4 raw material bisphenol A, NaOH aqueous solution, water, etc. supply pipe 5 methylene chloride supply pipe 6 pump 7 phosgene supply pipe 8 pipe reactor 9 tank reactor 10 refrigerator

Front page continued (72) Inventor Kenji Tsuruhara 1-1 Kurosaki Shiroishi, Hachimannishi-ku, Kitakyushu, Fukuoka Prefecture Mitsubishi Chemical Corporation Kurosaki Development Laboratory

Claims (9)

[Claims] 1. A method for producing a polycarbonate, which comprises reacting an alkali metal salt of diphenol in an aqueous phase with phosgene in an organic phase to obtain an oligomer according to a two-phase interfacial condensation method. The reaction product dissolves,
An organic phase containing an inert organic solvent that does not dissolve water, and a water phase containing water, diphenol and an alkali metal hydroxide,
A step of contacting under emulsification conditions to form an emulsion, and (2) contacting this emulsion with phosgene under condensation reaction conditions and under mixing conditions weaker than the above emulsification conditions to obtain oligomers. A method for producing a polycarbonate, which comprises the steps of: 2. The emulsification condition of the step (1) is such that the Weber number We is 1 × 10 ⁴ or more, and the mixing condition of the step (2) is that the Weber number We is less than 1 × 10 ⁴ . The method of claim 1, wherein conditions are employed. 3. As the emulsification condition of the step (1), a condition that P / q defined by the following formula is 200 kg · m / l or more is adopted, and as the mixing condition of the step (2), the following formula is used. The method according to claim 1, characterized in that a condition that the defined P / q is less than 200 kg · m / l is adopted. [Number 1] P / q = Np · ρ · n 3 · d 5 / (g · q) where, Np is a constant, a bath-type mixer 0.8, and 2.31 in a tubular mixer. ρ is the specific gravity of the emulsion in the system (kg / m ³ ), n is the number of revolutions of the stirrer (rps), d is the blade diameter of the stirrer (m), and g is the acceleration of gravity (m / se).
c ² ) and q represent the flow rate (l / sec) of the emulsion in the system, respectively. 4. Process according to claims 1 to 3, characterized in that the emulsion formation is carried out in the presence of at least one chain terminator and / or at least one condensation catalyst. 5. Process according to claims 1 to 4, characterized in that the emulsion formation is carried out in a dynamic mixer (mechanical emulsifier) and / or static mixer. 6. Contact with phosgene at a pressure of 0 to 10 kg /
cm ² G, the method of the preceding claims, wherein the carried out at a temperature 80 ° C. or less 7. The process according to claim 1, wherein the contact with phosgene is carried out in a piston flow reactor. 8. A method for producing a polycarbonate, which comprises reacting an alkali metal salt of diphenol in an aqueous phase with phosgene in an organic phase according to a two-phase interfacial condensation method to obtain an oligomer. Although the phosgene and the reaction product are dissolved, an organic phase containing an inert organic solvent that does not dissolve water and a water phase containing water, diphenol and an alkali metal hydroxide are brought into contact with each other under emulsifying conditions, and milk A step of forming a suspension and (2) contacting this emulsion with phosgene under a condensation reaction condition and under a mixing condition weaker than the above emulsification conditions to obtain an oligomer, in which case di- A method for producing a polycarbonate, which comprises a step of maintaining an emulsified state of an emulsion until the alkali metal salt of phenol disappears. 9. A method for producing a polycarbonate, which comprises reacting an alkali metal salt of diphenol in an aqueous phase with phosgene in an organic phase according to a two-phase interfacial condensation method to obtain an oligomer. Although the phosgene and the reaction product are dissolved, an organic phase containing an inert organic solvent that does not dissolve water and a water phase containing water, diphenol and an alkali metal hydroxide are brought into contact with each other under emulsifying conditions, and milk A step of forming a suspension, (2) contacting this emulsion with phosgene under condensation reaction conditions and under mixing conditions weaker than the above emulsification conditions to obtain an oligomer, in which case di- The step of maintaining the emulsified state of the emulsion until the alkali metal salt of phenol disappears, and (3) the organic phase in which the oligomer is dissolved is then separated from the aqueous phase, and an additional amount of the above-mentioned unreacted Active organic solvent Both the aqueous phase containing water and an alkali metal hydroxide, is contacted in the polycondensation reaction conditions, the production method of polycarbonate, characterized in that through the process of obtaining a polycarbonate.