JPH0655810B2 - Method for producing a polycarbonate-oligomer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a polycarbonate oligomer by reacting an aqueous alkaline solution of a divalent phenol with phosgene, and more specifically, the reaction is divided into a phosgenation reaction and an oligomerization reaction. By introducing the cooled, cooled oligomerization reaction product mixture into the phosgenation reactor, the phosgenation reaction should be carried out in a short time at an appropriate temperature and an appropriate concentration of the aqueous alkali solution of divalent phenol. The present invention relates to a continuous production method in which an oligomerization reaction is subsequently carried out in combination with a large amount of reaction product mixture.

[Prior art]

A method for continuously producing a polycarbonate oligomer by the reaction of an aqueous alkaline solution of a divalent 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 into the dilute phenol dilute aqueous alkaline solution. There's a problem. The method of passing the raw material through the packed tower (Japanese Patent Publication No. 414352) is difficult to remove the heat of reaction, and the reaction mixture does not flow uniformly in a steady state, so that local temperature rise easily occurs. There is a problem that the properties of the oligomer are not constant.

A method in which vaporized phosgene in a vapor phase is brought into contact with a solvent in a tubular reactor in the form of an atomized divalent phenol aqueous solution and the heat of reaction is removed by the heat of evaporation of the solvent (Japanese Patent Publication No. 46-21460). JP-A-56-44091), the reaction is carried out at a temperature close to the boiling point of the solvent, so that the decomposition of phosgene is large,
There is a problem that 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 problem, a method of attaching a cooling jacket to the reaction tube (Japanese Patent Laid-Open Nos. 58-108225 and 58-108226) has been proposed. It is necessary to reduce the diameter, which causes a dilemma that the reaction between the mist droplets in the reaction tube and the gas proceeds smoothly and becomes difficult.

A method in which an alkaline aqueous solution of divalent 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 (Japanese Patent Publication No. 54-4028).
No. 0), it is difficult to maintain the temperature of the initial reaction, and it is difficult to avoid decomposition of phosgene and chloroformate.

In the method of charging an alkaline aqueous solution of a divalent phenol to 0 ° C. or lower in a reactor (JP-A-5552321), the reaction mixture becomes sheared when methylene chloride which is commonly used as an organic solvent is used. Therefore, it is not suitable for a reaction using a tubular reaction column or a packed column.

As a method for removing the heat of reaction, a continuous production method of a 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]

An object of the present invention is to provide a method for continuously producing an oligomer having a constant property, which is capable of easily removing the heat of reaction generated by the reaction between an aqueous alkaline solution of a divalent phenol and phosgene with a simple facility. To do.

[Structure of Invention]

The present invention is an aqueous solution of divalent phenol, phosgene,
The organic solvent and the cooled reaction product mixture of the second reactor are mixed with an alkali aqueous solution of divalent phenol having a concentration of 55 to 150 g /
To the first reactor in an amount of
Allow to react for 0 seconds, then 1-2 at 10-30 ° C in the second reactor.
A method for producing a polycarbonate oligomer, which comprises reacting for 0 minutes.

Bisphenols used in the present invention are preferably bisphenols, 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-
Examples thereof include bis (3,5-dibromo-4-hydroxyphenyl) propane.

These divalent phenols are used by being dissolved 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 divalent phenol to alkali is preferably 1: 1.8 to 1: 3.5, more preferably 1: 2.0 to 1: 3.2. The concentration of the divalent phenol aqueous solution is preferably as high as possible, but is preferably 150 to 180 g / in view of the solubility of the divalent phenol. When preparing these solutions, it is necessary to set the temperature to 20 ° C. or higher. However, if the temperature is too high, the oxidation of the divalent phenol occurs, so the temperature is set to the minimum required temperature, or in a nitrogen atmosphere, or
It is preferable to add a small amount of a reducing agent such as hydrosulfite.

Phosgene is used in liquid or gaseous form, and is used alone or as a solution in an organic solvent. The preferred amount of use is influenced by the reaction conditions, particularly the temperature of the first reactor and the concentration of the alkaline aqueous solution of divalent phenol in which phosgene is mixed and reacted, and when the temperature exceeds 25 ° C. 5
When the amount is less than 5 g / mol, the number of moles of phosgene per mole of divalent phenol exceeds 1.2 moles and often exceeds 1.3 moles, but 1.0 to 1.2 moles are sufficient under the conditions of the present invention. 1.05 to 1.15 mol is more preferable.

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-
Examples thereof include ethane chloride, 1,1,2-3 ethane chloride, chloroform and chlorobenzene. 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 the volume of the aqueous solution of the divalent phenol is 0.2 to 1.0 with respect to the alkaline aqueous solution. It is preferably a ratio.

The amount of the reaction product mixed liquid of the second reactor introduced into the first reactor is 2 in 1 of the total amount of the amount of the aqueous phase therein and the amount of the aqueous alkaline solution of divalent phenol introduced at the same time. It is necessary to determine that the valency phenol is present in the range of 55 to 150 g. When it is less than 55 g, phosgene is decomposed, and when it exceeds 150 g, an alkali salt of a divalent phenol may be precipitated, and the effect of lowering the reaction temperature becomes insufficient, which is not preferable.

The first reactor used in the present invention is a small vessel having a mixing function inside. For example, a reaction tank equipped with a stirrer,
A reaction tube containing a filler such as glass spheres, Raschig rings, and stainless fibers, a reaction tube containing an orifice, a static mixer, etc., among them, a reaction tube containing a filler is particularly preferable. The length / inner diameter of these first reactors is preferably 5 or more, and a cooling jacket may be attached if necessary. The second reactor is a large container having a mixing function and a cooling function inside and / or outside, but a reaction tank equipped with an agitator and a cooling jacket and / or an external circulation cooler is preferable. The first reactor and the second reactor are connected directly or by a pipe, and the effective capacity ratio thereof is (0.5 to 20) / (60 to 1200). The second reactor and the first reactor are connected by separate pipes, and a liquid feed pump and a cooling heat exchanger are attached along the way. The reaction product mixed solution outlet can be provided between the liquid feed pump and the cooling heat exchanger or directly in the second reactor.

An example of the apparatus is shown in FIGS.

The reaction solution mixture obtained by cooling the aqueous divalent phenol solution, phosgene, the organic solvent, and the second reactor through the cooling heat exchanger is introduced into the first reactor for phosgenation reaction. These components may be introduced alone, but it is preferable to introduce them after mixing the aqueous solution of the divalent phenol and the reaction product mixture, and also introducing them after mixing phosgene and the organic solvent. preferable. When mixing these, it is sufficient to combine the pipes without providing a mixing tank, and if necessary, a packing material, a static mixer, or the like may be provided between the combination part and the inlet of the first reactor. You can put it in. It is not preferable to mix phosgene with a component other than the organic solvent, or to mix a component such as an amine or a monovalent phenol which affects the polymerization of the polycarbonate at the time of introduction because the effect of the present invention is impaired. The temperature of the reaction mixture in the first reactor is 10 to 25 ° C, preferably 1
It is necessary to maintain at 2 ~ 20 ℃, the reaction time
It must be between 0.5 and 20 seconds. Temperature is 10 ℃
If it is less than 25 ° C., an alkali salt of divalent phenol may be precipitated, and if it exceeds 25 ° C., a decomposition reaction of phosgene or chloroformate is caused, which is not preferable. Also, in order to complete the phosgenation reaction in the first reactor, 0.5
It requires more than a second, but not more than 20 seconds. The reaction time can be adjusted by adjusting the introduction rate of the raw materials. The temperature of the mixed solution in the reactor can be adjusted depending on the temperature of the organic solvent to be introduced and the reaction product mixed solution. These temperatures are usually 20 ° C. or lower, preferably 10 ° C. or lower, but actually the temperature in the reactor is 10 ° C. or lower.
It is determined to maintain -25 ° C, preferably 12-20 ° C.

The phosgenated reaction mixture continuously enters the second reactor and the oligomerization reaction proceeds. Here, the temperature of the mixed solution must be maintained at 10 to 30 ° C., and the reaction time must be between 1 and 20 minutes. When the temperature is lower than 10 ° C, the reaction rate becomes slow, and when the temperature is higher than 30 ° C, decomposition of chloroformate increases, which is not suitable. When the reaction time is less than 1 minute, the oligomerization reaction is insufficient, and when it exceeds 20 minutes, the average molecular weight of the oligomer becomes high, and it becomes difficult to control the molecular weight in the subsequent polymerization reaction.

A part of the produced oligomerization reaction mixture is taken out of the system directly from the second reactor or via a liquid feed pump, and the rest is cooled by a heat exchanger and introduced into the first reactor. The reaction product mixed liquid discharged out of the system contains an oligomer containing a hydroxyl group and an excess of chloroformic acid ester, and
It can be used as it is or after addition of monovalent phenol, amine, alkali, etc. for the polymerization reaction.

〔The invention's effect〕

In the production method of the present invention, the phosgenation reaction and the oligomerization reaction are separated and appropriate conditions are set for each reaction.
By adopting the method of suppressing the rapid reaction in the phosgenation reaction and introducing the cooled reaction product mixed solution to absorb the reaction heat, it is possible to maintain an appropriate reaction temperature which is a conventional problem. This can be done easily while maintaining an appropriate concentration of an aqueous alkaline solution of valent phenol. Therefore, the decomposition of phosgene and chloroformate is suppressed, and accordingly, the resulting oligomer has a small variation in the content ratio of the hydroxyl group and chloroformate, and the relative viscosity is sufficiently controlled within the preferable range. A uniform polymer can be easily obtained by the above polymerization reaction.

〔Example〕

 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. About 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. The solvent is evaporated from the organic phase and 0.700 g of the oligomer or polymer obtained by drying under reduced pressure is added to 100 ml of methylene chloride.
Dissolve in, and measure at 20 ° C. with an Ostwald viscometer.

(Terminal chlorine) 1.000 g of the oligomer obtained at the time of measuring the relative viscosity was dissolved in 250 ml of methylene chloride, triethylamine and water were added and mixed well, and then an indicator, dilute nitric acid and a fixed amount of silver nitrate were added, and N / 10 Titrate with aqueous ammonium thiocyanate solution. On the other hand, a blank is prepared in the same manner except that triethylamine is not added. Terminal chlorine (%)
Is calculated by the following equation.

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

(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 aqueous alkali solution, and the wavelength was measured with a uv spectrometer (Hitachi 200-10 type). 294 nm and 330 nm
Is measured, and the bisphenol A concentration is calculated from the following formula.

However, 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. 3 was used. The first reactor (1) has a length of 200 mm,
A tube having an inner diameter of 15 mm was filled with 50 g of a stainless fiber having a diameter of 0.5 mm, and the tube was installed so that the lower end thereof was below the reaction product mixed liquid surface of the second reactor (effective volume: about 28 ml). The second reactor (2) was a tank of 5, and a reaction product mixture outlet (6) was provided at a position of an effective capacity of 4. Jacket (3) and heat exchanger (5,
Cooling water was passed through 5 ').

24.1 Kg of bisphenol A was dissolved in 7.0 wt% caustic soda aqueous solution at 30 ° C to dissolve 165 g / bis caustic soda aqueous solution of bisphenol A, and 11.4 Kg of phosgene was dissolved in methylene chloride at -15 ° C to give 164 g / Each solution of phosgene in methylene chloride was prepared.

First, the water in the heat exchanger (5 ') was stopped, the caustic soda aqueous solution of bisphenol A was introduced into the second reactor through the conduits 7 and 11 at a flow rate of 42 / Hr, and at the same time, the methylene chloride solution of phosgene was 20 / Hr. Was introduced into the second reactor through the first reactor and reacted at a flow rate of. Reaction product mixture is outlet
When it begins to be discharged from (6), the reaction product mixture is sent to the heat exchanger (5) at a flow rate of 800 / Hr by the pump (4),
Return volume of / 15 to second reactor through conduit (11), 1/1 remaining
Five volumes are combined with a caustic soda solution of bisphenol A through a heat exchanger (5 ') through water and a conduit (7),
I was allowed to enter the reactor. At the inlet of the first reactor, the concentration of bisphenol A in the aqueous phase was about 100 g /. First
Heat exchanger to keep the temperature in the reactor at 18 ± 1 ℃
Adjust the temperature of water passing through (5 ') so that the temperature in the second reactor is 25 ±
The water temperature of the jacket (3) was adjusted so as to maintain 1 ° C. The reaction product mixture discharged from the discharge port (6) of the second reactor was sampled 6 times every 30 minutes and analyzed by the above method. From the 3rd time onward, the relative viscosity of the oligomer was 1.041 to 1.045, the terminal chlorine is 5.2-5.5%, the pH of the aqueous phase is 13 or more, the concentration of bisphenol A is 23-24g /,
The concentration of sodium carbonate was 4.8 to 5.5 g /, which were all extremely stable values.

Then, the remaining total 1.5 of the reaction product mixture sampled at the 3rd to 6th times was put in a 2 flask equipped with a stirrer 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, and the mixture was placed at 25 ° C.
And reacted for 2 hours. The obtained polycarbonate had a relative viscosity of 1.428 and a w / n of 2.48.

Example 2 The same apparatus as in Example 1 was used, and the conduit for the reaction product mixture was used.
The same operation as in Example 1 was carried out except that the amount fed to the first reactor via (7) was changed to 2/15 volumes. At this time, the concentration of bisphenol A in the aqueous phase at the inlet of the first reactor was about 75 g /. The analysis result of the reaction product mixture after the third sampling shows that the relative viscosity of the oligomer is 1.042 to 1.047, the amount of terminal chlorine is 5.3 to 5.9 g /, the pH of the aqueous phase is 13 or more, and the concentration of sodium carbonate is 4.7 to 5.6. g /, the concentration of bisphenol A
It was stable at 21-23g /.

As a result of the polymerization, the relative viscosity was 1.425 and the w / n was 2.73.

Example 3 The first reactor of Example 1 was first charged with 10 g of stainless fiber instead of 50 g of stainless fiber, and 20 g of glass balls having a diameter of 3 mm was charged thereon (effective volume of about 27 ml).
The same apparatus as in Example 1 was used except for the above, and the same operation was performed. The analysis results of the reaction product mixture after the third sampling show that the relative viscosity of the oligomer is 1.044 to 1.047, the amount of terminal chlorine is 5.0 to 5.6 g /, the pH of the aqueous phase is 13 or more, and the concentration of sodium carbonate is 4.6 to 5.3. The concentration of g / and bisphenol A is 20
It was stable at ~ 22g /.

As a result of the polymerization, the relative viscosity was 1.428 and the w / n was 2.68.

Comparative Example 1 The same apparatus as in Example 1 was used, and a conduit for the reaction product mixture was used.
The same operation as in Example 1 was carried out except that it was not sent to (7). The temperature of the first reactor fluctuated between 32 and 39 ° C. The analysis results of the reaction product mixture after the third sampling show that the relative viscosity of the oligomer is 1.046 to 1.054, the terminal chlorine is 4.5 to 5.3%, the pH of the aqueous phase is 13 or more, the concentration of bisphenol A is 20 to 27 g /, The concentration of sodium carbonate was 8 to 10 g /, and all were unstable.

Also, the result of the polymerization reaction was that the relative viscosity of the polymer was 1.383.
And w / n was 2.90.

Comparative Example 2 The same apparatus as in Example 1 was used, and a conduit for the reaction product mixture was used.
The same operation as in Example 1 was carried out except that the amount fed to the first reactor via (7) was changed to 6/15 volume. At this time, the concentration of bisphenol A in the aqueous phase at the inlet of the first reactor was about 48 g /. The analysis results of the reaction product mixture after the third sampling show that the relative viscosity of the oligomer is 1.037 to 1.045, the amount of terminal chlorine is 4.8 to 5.8 g /, the pH of the aqueous phase is 13 or more, and the concentration of bisphenol A is 22 to 29g /, concentration of sodium carbonate is 7.
All were unstable with 8 to 9.9 g /.

Also, the result of the polymerization reaction shows that the relative viscosity of the polymer is 1.39.
5, w / n was 2.93.

[Brief description of drawings]

1-4 are schematic diagrams of examples of devices used in the present invention. 1: 1st reactor, 2: 2nd reactor 3: Jacket, 4: Liquid sending pump 5,5 ': Cooling heat exchanger 6: Reaction product mixed liquid discharge port 7: Cooled reaction product mixed liquid conduit 8: Alkaline aqueous solution inlet for divalent phenol 9: Phosgene inlet 10: Organic solvent inlet 11: Reaction product mixture liquid circulation pipe

Claims (1)

[Claims] 1. An alkali aqueous solution of divalent phenol, phosgene, an organic solvent and a cooled reaction product mixture of the second reactor, wherein the concentration of the alkali aqueous solution of divalent phenol is 55 to 15.
Introduced into the first reactor in an amount of 0g /, 0.5 at 10-25 ℃
Allow to react for ~ 20 seconds, then in the second reactor at 10 ~ 30 ° C for 1
A method for producing a polycarbonate oligomer, which comprises reacting for 20 minutes.