JPH0680110B2 - Continuous production method of polycarbonate-boner oligomer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a polycarbonate oligomer by the reaction of an aqueous alkaline solution of a dihydric phenol with phosgene, and more specifically, the reaction is carried out in an aqueous phase in a reaction tower. On the other hand, the present invention relates to a continuous production method in which an organic solvent having a specific volume ratio is used and a cooled oligomerization reaction product mixture is circulated and supplied under appropriate conditions.

[Prior Art] A method for continuously producing a polycarbonate oligomer by reacting an aqueous alkaline solution of a dihydric phenol with phosgene is known.

The cascade method in which small reactors with a stirrer are connected in series makes it relatively easy to remove the heat of reaction, but the decomposition of phosgene increases due to the introduction and reaction of phosgene in a dilute phenol dilute aqueous alkaline solution. There's a problem. Method of passing raw materials through a packed tower (Japanese Patent Publication No. 41-4352)
Is difficult to remove the heat of reaction and the flow of the reaction mixture does not easily reach a uniform steady state, so local temperature rise easily occurs,
Therefore, there is a problem that the properties of the oligomer are not constant.

A method of contacting vaporized phosgene in an atomized alkaline aqueous solution of a dihydric phenol and a solvent in a tubular reactor and removing the heat of reaction by the heat of evaporation of the solvent (JP-B-46-21460, JP-B-56) However, since the reaction is carried out at a temperature near the boiling point of the solvent, phosgene is decomposed a lot and the reproducibility during polymerization is not good. Another problem is that the reaction tube becomes long because the evaporated solvent is condensed and liquefied. To solve this, a method of attaching a cooling jacket to the reaction tube (Japanese Patent Laid-Open No. 58-108225 and Japanese Patent Laid-Open No. 58-108225)
No. 108226 gazette) has been proposed, but it is necessary to reduce the tube diameter in order to perform efficient cooling, which causes a dilemma that it becomes difficult for the reaction of fog droplets and gas in the reaction tube to proceed smoothly. .

Maintaining the temperature of the initial reaction is also a method (Japanese Patent Publication No. 54-40280) in which an alkaline aqueous solution of a dihydric phenol and an organic solvent solution of phosgene are initially reacted in a charging pipe and then the latter reaction is carried out in a large reaction tank. Is difficult to avoid, and it is difficult to avoid decomposition of phosgene or chloroformate.

In the method of charging an alkaline aqueous solution of a dihydric phenol to 0 ° C. or lower and charging it to a reactor (Japanese Patent Laid-Open No. 55-52321), when methylene chloride which is commonly used as an organic solvent is used, the reaction mixture becomes sherbet-like. Therefore, it is not suitable for a reaction using a tubular reaction column or a packed column.

As a method for removing such heat of reaction, a continuous production method of polymer linear polycarbonate in which a cooled high molecular weight reaction mixture is re-supplied (Japanese Patent Laid-Open No. 47-14297) has been proposed.
However, in this method, since phosgene is diluted with another inert gas and charged, the reaction product must be separated into gas and liquid, and since amine is present and the system is likely to be in an emulsified state, phosgene and chlorobenzene are not used. There is a problem that the decomposition of the formate ester is rather large.

[Object of the invention] The object of the present invention is to easily remove the heat of reaction generated by the reaction between an aqueous alkaline solution of a dihydric phenol and phosgene with simple equipment, and to continuously prepare an oligomer having a certain property continuously. It is to provide a manufacturing method.

[Structure of the Invention] The present invention provides an alkali aqueous solution of a dihydric phenol, phosgene, an organic solvent in an amount of 0.3 to 1.0 times the volume of the alkali aqueous solution, and a cooled reaction mixture from one end of a reaction tower to obtain a dihydric phenol in a total alkali aqueous solution. This is a continuous production method of a polycarbonate oligomer in which phenol is continuously supplied at a rate of 55 to 150 g / and reacted at 10 to 25 ° C.

As the dihydric phenol used in the present invention, bisphenols are preferable, and particularly 2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as bisphenol A)
Is preferred. Other bisphenols include, for example:
Bis (4-hydroxyphenyl) methane, 1,1-bis (4
-Hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) pentane, 2,2-bis (4-hydroxyphenyl)
Hexane, 2,2-bis (4-hydroxyphenyl) 4-methylpentane, 1,1-bis (4-hydroxyphenyl) 1
-Phenylethane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxy-3-)
Methylphenyl) propane, 2,2-bis (4-hydroxyphenyl) hexafluoropropane, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane and the like can be mentioned.

These dihydric phenols are used by dissolving them in an alkaline aqueous solution. As the alkali, alkali metal hydroxides such as caustic soda and caustic potash are preferably used. The concentration is preferably 5 to 10% by weight. The molar ratio of dihydric phenol and alkali is preferably 1: 1.9 to 1: 3.2, and further 1: 2.0 to
1: 2.5 is preferable. The concentration of the dihydric phenol in the alkaline aqueous solution is preferably as high as possible, but is preferably 150 to 180 g / in view of the solubility of the dihydric phenol. When preparing these solutions, it is necessary to set the temperature to 20 ° C or higher, but if the temperature is too high, the oxidation of the dihydric phenol will occur, so the temperature must be the minimum required, and it should be performed in a nitrogen atmosphere or hydrosulfite. It is preferable to add a small amount of a reducing agent such as.

Phosgene is used in liquid or gaseous form, and is used alone or as a solution in an organic solvent. The preferable amount thereof is influenced by the reaction conditions, particularly the temperature in the reaction column and the concentration of the aqueous alkaline solution of the dihydric phenol mixed and reacted with phosgene, and when the temperature exceeds 25 ° C or the concentration is 55 g /
When it is less than 1, the number of moles of phosgene with respect to 1 mole of dihydric phenol exceeds 1.2 moles and often exceeds 1.3 moles, but 1.0 to 1.2 moles is sufficient under the conditions of the present invention, and 1.05 to 1.15 mol is more preferred.

The organic solvent used in the present invention is a solvent which is inert to the reaction, dissolves phosgene and polycarbonate, and is substantially insoluble in water, for example, methylene chloride, 1,2-ethane chloride, 1,1,1. 2-3, ethane chloride, chloroform, chlorobenzene and the like can be mentioned. The amount of the solvent used is not particularly limited, but the concentration of the produced polycarbonate oligomer is about 10 to 35% by weight, and is 0.3% based on the aqueous alkaline solution of the dihydric phenol, that is, the aqueous phase.
The volume ratio is ~ 1.0. When it is less than 0.3 or when it exceeds 1.0, decomposition of phosgene occurs, and the properties of the produced oligomer vary.

The amount of the reaction product mixed solution introduced into the reaction tower is the sum of the amount of the aqueous phase therein and the amount of the aqueous alkali solution of the dihydric phenol introduced into the tower, that is, the total amount of the aqueous alkali solution 1
It is necessary to determine that the dihydric phenol is present in the range of 55 to 150 g. If it is less than 55 g, phosgene may decompose, and if it exceeds 150 g, alkali salts of dihydric phenol may precipitate, and the temperature in the reaction tower is 25 ° C.
May exceed. It is necessary to maintain the temperature in the reaction tower at 10 to 25 ° C. If the temperature is lower than 10 ° C, an alkali salt of a dihydric phenol may be precipitated, and if the temperature exceeds 25 ° C, phosgene or chloroformate is decomposed, resulting in a large variation in the content ratio of hydroxyl groups and chloroformate of the produced oligomer.

The case where the apparatus of FIG. 1 is used will be described below. Phosgene is introduced from the upper part of the reaction tower 1 through the introduction pipe 2.
A solvent is supplied through 3 and an alkaline aqueous solution of a dihydric phenol is supplied through an introducing pipe 4. A part of the reaction mixture produced in the reaction tower 1 is discharged from the discharge port 7 through the pump. The balance is cooled by the heat exchanger 8 and circulated and supplied to the reaction tower through the pipe 9. The reaction tower is a cylindrical reactor with an inner diameter to length ratio of 1: 5 to 1:50. Inside it, glass balls, Raschig rings, stainless fibers, etc. are placed so that the contents become turbulent. Be filled or
Built-in orifice etc. In order to maintain the temperature of the reaction tower at 10 to 25 ° C., the temperatures of the reaction product mixture, the raw materials and the solvent to be supplied are adjusted. The residence time in the reaction column, that is, the oligomerization reaction time is preferably 10 to 300 seconds, more preferably 20 to 100 seconds. If it is less than 10 seconds, the reaction is insufficient, and if it is 300 seconds or more, the decomposition of chloroformate takes precedence over the reaction. The residence time in the reaction tower is adjusted by the effective volume of the reaction tower and the flow rates of the reaction product mixture, the raw materials, and the solvent supplied to the reaction tower.

In addition, in the method of the present invention, addition or mixing of amine, quaternary ammonium salt, monohydric phenol or the like causes decomposition of phosgene or chloroformate or regulation of the molecular weight of the produced oligomer. Strict exclusion is necessary.

The polycarbonate oligomer mixture obtained by the method of the present invention is reproducibly formed into a high molecular weight polycarbonate by adding a monohydric phenol, an amine, an alkali and the like to cause a polycondensation reaction.

[Effect of the Invention] In the method for producing a polycarbonate oligomer using a reaction tower of the present invention, by circulating and supplying the cooled reaction product mixture solution to the reaction tower, it is possible to easily maintain an appropriate reaction temperature, which has been a problem in the past. Moreover, since the concentration of the aqueous dihydric phenol solution can be adjusted appropriately and the organic solvent is used in a volume ratio of 0.3 to 1.0 with respect to the aqueous phase, the decomposition of phosgene and chloroformate can be suppressed. Therefore, the obtained oligomer has a small variation in the content ratio of the hydroxyl group and the chloroformic acid ester, and the relative viscosity is sufficiently controlled within the preferable range, so that a uniform polymer can be easily obtained by the subsequent polycondensation reaction. it can.

Hereinafter, the present invention will be specifically described with reference to examples.

Each characteristic value was measured by the following method.

(Relative Viscosity) Methylene chloride is added to the discharged reaction product mixture and mixed, and then allowed to stand to separate into an organic phase and an aqueous phase. Almost the same amount of pure water is added to this organic phase, mixed thoroughly, and then passed through a paper to stand and separate. Washing is repeated in the same manner until chlorine ions in the aqueous phase are no longer detected by silver nitrate. Evaporating the solvent from the organic phase and drying 0.700 g of the oligomer or polymer obtained by drying under reduced pressure, 100 ml of methylene chloride
Dissolve in and measure with an Ostwald viscometer at 20 ° C.

(Terminal chlorine) 1.0 g of the oligomer obtained in measuring the relative viscosity was dissolved in 250 ml of methylene chloride, triethylamine and water were added,
After mixing well, add indicator, dilute nitric acid and silver nitrate, and titrate with N / 10 ammonium thiocyanate aqueous solution. On the other hand, a blank is prepared in the same manner except that triethylamine is not added. The terminal chlorine (%) is calculated by the following formula.

Here, V ₀ is the blank titer (ml), V ₁ is the sample titer (ml), f is the titer of the ammonium thiocyanate aqueous solution, and W is the sample amount (g).

(Terminal OH group amount) The organic phase obtained by allowing the reaction product mixture to stand and separate is diluted with methylene chloride, and then the absorbance at 284,272 nm (A284nm, A272nm)
UV-visible absorption spectrophotometer (Hitachi Ltd. 200-
10 type) to measure the absorbance ratio A284nm / A272nm. A
A larger 284 nm / A272 nm indicates a larger amount of terminal OH groups.

(Concentration of bisphenol A in the aqueous phase) When measuring the relative viscosity, a part of the initially separated aqueous phase was diluted with a dilute alkaline aqueous solution, and the wavelength was 294 nm with a uv spectrometer (Hitachi 200-10 type). And the absorbance at 330 nm are measured, and the bisphenol A concentration is calculated from the following formula.

Bisphenol A concentration (g /) = (A ₁ −A ₀ ) × n × 1/22 where A ₁ and A ₀ are the absorbance at 294 nm and 330 nm, respectively.
n is the dilution ratio.

(Sodium Carbonate Concentration in Aqueous Phase) Regarding the remaining aqueous phase used for measuring the bisphenol A concentration, the sodium carbonate concentration (g /) is determined by the Winkler method.

(Molecular weight distribution) A 1 wt% tetrahydrofuran solution of the polymer obtained in relative viscosity measurement was prepared and subjected to gel permeation chromatography (Waters ALC / GPC 201 type).
The ratio of the weight average molecular weight to the number average molecular weight (w /
n) is calculated. The closer w / n is to 1, the narrower the molecular weight distribution is.

Example 1 The apparatus of FIG. 1 was used. The reaction tower has a length of 2200 mm and an inner diameter of 70 m.
It is a cylindrical tube with an effective capacity of 5.9, filled with 6.5 kg of 13 mm x 13 mm Raschig rings in an m glass lining pipe.

Bisphenol A was added to a 7.0 wt% caustic soda aqueous solution.
165 g / bis caustic soda aqueous solution of bisphenol A was dissolved at -15 ° C, and phosgene was dissolved in methylene chloride at -15 ° C to prepare 170 g / phosgene of methylene chloride solution.

First, a caustic soda aqueous solution of bisphenol A was added to the reaction tower 1
The cooling water is passed through the heat exchanger 18 for cooling, and then the pump 5 is operated to circulate the caustic soda aqueous solution of bisphenol A, and the methylene chloride solution of phosgene is supplied from the introduction pipe 2 at a rate of 70.6 / Hr. did. Then, adjust the valve 6 to adjust the circulation amount from the heat exchanger 8 to the pipe 9 to 150.
/ Hr, and the supply of the caustic soda aqueous solution of bisphenol A from the introduction pipe 4 was started at a rate of 184.3 / Hr. The concentration of bisphenol A in the aqueous phase that reacts with phosgene is about 112 g.
/Met.

When the temperature of the cooling water passed through the heat exchanger for cooling was adjusted,
The internal temperature of the reaction tower reached 20 ± 1 ° C. The reaction product mixture discharged through the outlet 6 through the valve 6 is removed every 30 minutes after 1 hour.
After sampling 10 times and analyzing by the above method,
Relative viscosity of oligomer is 1.038-1.042, terminal chlorine is 5.5-
5.8%, A284nm / A272nm is 0.312 ~ 0.320, the concentration of bisphenol A in the aqueous phase is 23 ~ 24g /, and the concentration of sodium carbonate is 4.5.
All were extremely stable at ~ 5.2 g /.

Next, the remaining 1.5 parts of the sampled reaction product mixture
Was added together with 55 g of a 30% by weight aqueous sodium hydroxide solution, 3.2 g of t-butylphenol, and 0.15 g of triethylamine into a 2-flask equipped with a stirrer and reacted at 25 ° C. for 2 hours. The obtained polycarbonate had a relative viscosity of 1.429 and a w / n of 2.46.

Example 2 Using the same equipment as in Example 1, piping 9 for the reaction product mixture
The operation was performed in the same manner as in Example 1 except that the circulation rate for obtaining was 300 / Hr. At this time, the concentration of the aqueous phase bisphenol A at the inlet of the reaction tower was about 88 g /. After 1 hour, sampling was performed 10 times every 30 minutes, and as a result, the relative viscosity of the oligomer was 1.037 to 1.043, the terminal chlorine was 5.6 to 5.9%, A284nm / A272n.
m is 0.315 to 0.321, the concentration of bisphenol A in the aqueous phase is 21
The concentration of sodium carbonate was ~ 23g /, and the concentration of sodium carbonate was stable at 4.8 ~ 5.5g /.

As a result of the polymerization, the relative viscosity was 1.424 and the w / n was 2.65.

Comparative Example 1 The same apparatus as in Example 1 was used, and the reaction product mixture piping 9 was used.
The same operation as in Example 1 was carried out except that the circulation rate after passing was 1000 / Hr. At this time, the concentration of bisphenol A in the aqueous phase at the inlet of the reaction tower was about 45 g /. Every 30 minutes after 1 hour
As a result of sampling 10 times and analyzing, the relative viscosity of the oligomer is 1.033 to 1.041, the terminal chlorine is 4.7 to 5.8%, A284nm / A
The density at 272 nm was 0.335 to 0.383, the concentration of bisphenol A in the aqueous phase was 21 to 29 g /, and the concentration of sodium carbonate was 5.8 to 9.8 g /.

The result of the polymerization reaction is that the relative viscosity of the polymer is 1.386,
The w / n was 2.95.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an example of a device used in the present invention. 1: reaction tower, 2: phosgene alone or an organic solvent solution inlet tube, 3:
Organic solvent inlet pipe, 4: Dihydric phenol aqueous alkaline water inlet pipe, 5: Liquid feed pump, 6: Valve for adjusting discharge amount of reaction product mixture, 7: Discharge port of reaction product mixture, 8: Cooling Heat exchanger, 9: Reaction product mixture liquid circulation piping

Claims (1)

[Claims] 1. An alkali aqueous solution of dihydric phenol, phosgene, an organic solvent having a volume of 0.3 to 1.0 times that of the alkali aqueous solution, and a cooled reaction mixture are introduced from one end of a reaction tower to obtain a divalent phenol concentration in the total alkali aqueous solution. Is continuously supplied at a rate of 55 to 150 g /, and the reaction is carried out at 10 to 25 ° C. for continuous production of a polycarbonate oligomer.