JP2002080578A - Method for manufacturing polycarbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a polycarbonate sufficiently improved in heat resistance by allowing the phenolic hydroxy groups in the polycarbonate to react with an aryl chloroformate. SOLUTION: The reaction for manufacturing polycarbonate through an interfacial polymerization using phosgene and a bifunctional phenol as main raw materials is carried out as follows: after the aqueous phase is separated from the polymerization liquid, an aryl chloroformate of formula (1) (wherein, Ar is a monovalent aromatic group) containing phosgene in an amount of <=150 ppm is added to the organic phase in such a manner that the amount of the aryl chloroformate added is equimolar to two times moles based on the terminal phenolic hydroxy groups of the obtained polycarbonate to convert the terminal phenolic hydroxy groups to aryl carbonate groups.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polycarbonate, and more particularly, to a method for producing a polycarbonate having improved heat resistance.

[0002]

2. Description of the Related Art Polycarbonate resins are excellent in mechanical strength (particularly, impact resistance), heat resistance, electrical properties, etc., and are widely used as engineering plastics in various fields such as electric / electronic equipment fields and automobile fields. I have. Further, there are fields in which heat resistance is further required depending on applications such as thin sheets and high-temperature high-speed injection molded products. It has been known that a phenolic hydroxyl group in a polycarbonate is reacted with an arylchloroformate for the purpose of improving the heat resistance of the polycarbonate to reduce the residual amount of the phenolic hydroxyl group (JP-A-58-8482).
No. 2). However, the improvement in heat resistance was not sufficient.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a polycarbonate whose heat resistance has been sufficiently improved by reacting a phenolic hydroxyl group in the polycarbonate with an arylchloroformate. It is intended to provide.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the above-mentioned object of the present invention can be met by using a specific aryl chloroformate, and complete the present invention. Reached.

That is, the gist of the present invention is as follows. 1. Phosgene, a method for producing polycarbonate by an interfacial polymerization method using dihydric phenols as a main raw material,
After separating the aqueous phase from the polymerization solution, the organic phase has the following general formula (1) having a phosgene content of 150 ppm or less.

[0006]

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(In the formula, Ar represents a monovalent aromatic group.)
The arylchloroformate represented by is equimolar to the terminal phenolic hydroxyl group of the obtained polycarbonate.
A method for producing a polycarbonate, comprising adding a 2-fold molar amount to convert a terminal phenolic hydroxyl group into an aryl carbonate group. 2. 2. The method for producing a polycarbonate according to the above 1, wherein the arylchloroformate has an APHA of 30 or less.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The method for producing a polycarbonate of the present invention is an interfacial polymerization method using phosgene and dihydric phenols as main raw materials. That is, phosgene, an alkaline aqueous solution of a dihydric phenol, a molecular weight regulator and an organic solvent are supplied to a polymerization reactor to cause a polycondensation reaction. First, raw materials will be described sequentially.

Although there are many types of the above-mentioned dihydric phenols, 2,2-bis (4-hydroxyphenyl) propane (commonly called bisphenol A) is particularly preferable. As dihydric phenols other than bisphenol A, for example,
Bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4
-Hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) octane, 2,2-bis (4-hydroxy-1-methylphenyl) propane, 1,1-bis (4-hydroxy-tert-butylphenyl) ) Propane, 2,2-bis (4-hydroxy-3-bromophenyl) propane, 2,2-bis (4-hydroxy-3,5
-Tetramethylphenyl) propane, 2,2-bis (4
-Hydroxy-3-chlorophenyl) propane, 2,2
-Bis (4-hydroxy-3,5-tetrachlorophenyl) propane, 2,2-bis (4-hydroxy-3,5
Bis (hydroxyaryl) alkanes such as -tetrabromophenyl) propane; bis (hydroxyaryl) arylalkanes such as 2,2-bis (4-hydroxyphenyl) phenylmethane and bis (4-hydroxyphenyl) naphthylmethane; 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-
Bis (hydroxyaryl) cycloalkanes such as (hydroxyphenyl) -3,5,5-trimethylcyclohexane; 4,4′-dihydroxyphenyl ether;
Dihydroxyaryl ethers such as 4'-dihydroxy-3,3'-dimethylphenyl ether; 4,4'-
Dihydroxydiaryl sulfides such as dihydroxydiphenyl sulfide and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide; 4,4'-dihydroxydiphenyl sulphoxide and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulphoxide Dihydroxydiarylsulfoxides; dihydroxydiarylsulfones such as 4,4'-dihydroxydiphenylsulfone and 4,4'-dihydroxy-3,3'-dimethyldiphenylsulfone; dihydroxydiphenyls such as 4,4'-dihydroxydiphenyl And the like. These dihydric phenols may be used alone or as a mixture of two or more.

As the alkali of the above-mentioned aqueous solution of dihydric phenols, sodium hydroxide, potassium hydroxide and sodium carbonate are used, and sodium hydroxide is preferred.

In order to improve the flow characteristics of the polycarbonate, preferably, the above-mentioned dihydric phenols are used in an amount of 0.04.
5 to 2.0 mol% of trihydric or higher polyhydric phenols can be used together with dihydric phenols. The trihydric or higher polyhydric phenols are generally referred to as branching agents.
1,1-tris (4-hydroxyphenyl) ethane, α,
α ′, α ″ -tris (4-hydroxyphenyl) -1,
3,5-triisopropylbenzene, 1- [α-methyl-α- (4′-hydroxyphenyl) ethyl] -4-
[Α ′, α′-bis (4 ″ -hydroxyphenyl) ethyl] benzene, phloroglucin, trimellitic acid, isatin bis (o-cresol) and the like.

The molecular weight regulator is also called a terminal terminator, and is generally phenol, p-cresol, pt-butylphenol, pt-octylphenol, p-cumylphenol, p-nonylphenol, pt-amylphenol, Monohydric phenols such as p-dodecylphenol are used.

As the above-mentioned organic solvent, methylene chloride,
Chloroform, chlorobenzene and the like can be mentioned, but methylene chloride is preferred. Further, in the above reaction, tertiary aliphatic amines such as triethylamine, tributylamine and N-ethylpiperidine can be used as a catalyst, if necessary.

The above-mentioned polycondensation reaction may be carried out in a single step by charging the above-mentioned raw materials into a polymerization vessel. It may be performed by a two-stage method.

The polycarbonate in the organic phase obtained by separating the aqueous phase from the polymerization solution containing the polycarbonate produced by the above method usually has a terminal phenolic hydroxyl group of 20 to 300.
It contains ppm. In addition, several thousand ppm of an alkaline aqueous phase remains in the organic phase.

In the present invention, the above organic phase is represented by the following general formula (1)

[0017]

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(Wherein Ar is as defined above) is added. As the aryl chloroformate, phenol, pt-butylphenol, 2,6-dimethyl-phenol, 4-
(1,1,3,3-tetramethylbutyl) -phenol and the like can be mentioned.

The above aryl chloroformates are prepared from phenols and phosgene. The amount of phosgene in the aryl chloroformate must be less than 150 ppm. If it exceeds 150 ppm, the amount of chloroformate in the polycarbonate will increase, and the improvement in heat resistance of the polycarbonate will not be observed. Preferably 12
It is 0 ppm or less. Regarding the color tone of the aryl chloroformate, see APHA [JIS K 243].
5 (1992), Hazen standard colorimetric liquid number (APH)
A) 5 to 50 were prepared and the color tone was evaluated visually]]. If it exceeds 30, the improvement in heat resistance of the polycarbonate may be small. The amount of phosgene and the color tone can be controlled by vacuum distillation of aryl chloroformate.

The amount of the above-mentioned arylchloroformate to be added is equimolar to 2 times the molar amount of the phenolic hydroxyl group at the terminal of the polycarbonate in the organic phase. If the amount is less than the equimolar amount, the residual hydroxyl groups in the polycarbonate will increase, and the heat resistance of the polycarbonate will not be improved, and even if the molar amount exceeds 2 times, the amounts of the chloroformate, diaryl carbonate and hydroxyaryl will increase. Thus, no improvement in heat resistance can be seen. Preferably 1.
It is 2-1.7 times the molar amount.

The above-mentioned aryl chloroformate is generally used as a 1 to 4% by mass solution in the organic solvent used for the polymerization reaction. Regarding the addition time of the above aryl chloroformate, the organic phase obtained by separating the aqueous phase from the polymerization solution may be added to the organic phase after alkali washing, or may be added to the organic phase before alkali washing. Is also good. When added to the organic phase before alkali washing, the aryl chloroformate is added at the same time as 0.01.
0.08 N dilute aqueous alkaline solution is added to the organic phase
Addition of up to 25% by volume can be performed at the same time as alkali washing, which is convenient. When the above-mentioned diluted alkaline aqueous solution is not added, it is necessary to wash the organic phase with alkali after treatment with aryl chloroformate.

The above treatment with the aryl chloroformate may be carried out in a stirring tank. However, when the treatment is carried out in a line mixer and a device provided with a pipe for securing a residence time downstream of the line mixer, the organic phase containing the polycarbonate is converted. A continuous phase and an alkaline aqueous phase are in a suspended state in which they are dispersed phases, and the efficiency is high and preferred. The treatment with the aryl chloroformate may be carried out for a residence time such that the residual amount of terminal phenolic hydroxyl groups in the polycarbonate is less than 20 ppm, and is usually 5 to 20 minutes.

As described above, the terminal phenolic hydroxyl group of the polycarbonate can be converted to an aryl carbonate group by the aryl chloroformate treatment. The organic phase from which the alkali aqueous phase has been separated after the aryl chloroformate treatment, or the organic phase obtained by subjecting the organic phase to alkali washing, is washed with an acid and water until the electrolyte disappears. After the washing is completed, a poor solvent such as acetone, hexane, heptane or the like is added to the organic phase if necessary, followed by concentration and drying to obtain polycarbonate flakes.

The obtained polycarbonate flake has a viscosity-average molecular weight of 10,000 to 100,000, a residual phenolic hydroxyl group of less than 20 ppm, and an unreacted arylchloroformate of 0.5 ppm or less. is there. The viscosity average molecular weight (Mv)
Measured the viscosity of the methylene chloride solution at 20 ° C. using an Ubbelohde viscometer and calculated the intrinsic viscosity [η].
And [η] = 1.23 × 10 ⁻⁵ Mv ^0.83 .

The polycarbonate flakes obtained according to the present invention may optionally contain additives or other synthetic resins, elastomers and the like. First, as additives, for example, antioxidants such as hindered phenol-based, phosphorus-based (phosphite-based, phosphate-based, etc.) and amine-based, such as benzotriazole-based and benzophenone-based ultraviolet absorbers, For example, hindered amine-based light stabilizers such as aliphatic carboxylic acid ester-based, paraffin-based, silicone oil, and internal lubricants such as polyethylene wax, mold release agents, flame retardants, flame retardant assistants, antistatic agents, colorants, and the like. Can be mentioned.

Examples of other synthetic resins include resins such as polyethylene, polypropylene, polystyrene, AS resin (acrylonitrile-styrene copolymer), ABS resin (acrylonitrile-butadiene-styrene copolymer), and polymethyl methacrylate. Can be.
Examples of the elastomer include isobutylene-isoprene rubber, styrene-butadiene rubber, ethylene-propylene rubber, and acrylic elastomer.

The above components may be blended and kneaded in a usual manner, for example, a ribbon blender, a drum tumbler, a Henschel mixer, a Banbury mixer, a single screw extruder, a twin screw extruder, a co-kneader, It can be performed by a method using a multi-screw extruder or the like. The polycarbonate resin thus obtained can be manufactured into various molded products by applying various known molding methods, for example, injection molding, hollow molding, extrusion molding, compression molding, calendar molding, rotational molding and the like.

[0028]

EXAMPLES The present invention will be described more specifically with reference to Production Examples, Examples and Comparative Examples, but the present invention is not limited by these Examples. Production Example [Production of Polycarbonate Oligomer] A bisphenol A concentration of 1 in a 5.6 mass% aqueous sodium hydroxide solution was used.
Bisphenol A was dissolved to 3.5 mass% to prepare an aqueous sodium hydroxide solution of bisphenol A. 41 liter / hr of aqueous sodium hydroxide solution of bisphenol A, 17 liter / hr of methylene chloride
At a flow rate of 4.0 kg / hr and an inner diameter of 6 kg.
mm and a tube length of 30 m. The tubular reactor had a jacket portion, and the temperature of the reaction solution was kept at 40 ° C. or lower by passing cooling water through the jacket.

The reaction solution exiting the tubular reactor is continuously introduced into a baffled tank reactor having an inner volume of 40 liters equipped with a retreating wing, and 2.8 liters of an aqueous sodium hydroxide solution of bisphenol A is further added thereto. / Hr, 25% by weight aqueous sodium hydroxide solution 0.07 L / hr, water 17 L / hr, 1% by weight aqueous triethylamine solution 0.32
The reaction was carried out by adding liter / hr. The reaction solution overflowing from the tank reactor was continuously withdrawn, and the aqueous phase was separated and removed by standing, and the methylene chloride phase was collected.
The concentration of the polycarbonate oligomer thus obtained was 320 g / l, and the chloroformate group concentration was 0.70 mol / l.

[Production of Polycarbonate] The above oligomer solution was 20 liter / hr, methylene chloride was 11 liter / hr, 4.1% by mass of pt-butylphenol in methylene chloride was 4.3 liter / hr, 1% by mass aqueous solution of triethylamine was 0%. 2 liter / hr, aqueous solution of sodium hydroxide of bisphenol A 12 liter / hr, 25
0.90 liter / hr of a mass% aqueous sodium hydroxide solution
Has a turbine blade having a diameter of 43 mm and a diameter of 48 mm. K. The mixture is supplied to a pipeline mixer 2SL (manufactured by Tokushu Kika Kogyo Co., Ltd.) and mixed under a rotation of 3,000 rpm, and the mixed solution is continuously provided with a jacketed inner volume of 80 liters and a 5-stage paddle stirring tank with a paddle blade. To carry out a polymerization reaction. Cooling water at 15 ° C. was flowed through the jacket, and the temperature of the polymerization liquid was set at 30 ° C.

After diluting the polymerization solution overflowing from the upper part of the tower reactor with 14 liters / hr of methylene chloride, the aqueous phase was removed by a centrifugal extractor (manufactured by Kawasaki Heavy Industries, Ltd.), and the concentration was 176 g containing almost no bisphenol A. / L of a methylene chloride solution A of polycarbonate was continuously obtained. The polycarbonate has a terminal phenolic hydroxyl group of 170p.
pm.

Example 1 A methylene chloride solution containing the above polycarbonate in methylene chloride A 48 liter / hr, a methylene solution containing 2.0% by mass of phenylchloroformate (a) shown in Table 1 0.73 liter / hr, 0 8.0 liter / hr of a 0.07N aqueous sodium hydroxide solution was continuously mixed using a line mixer.
After passing through a pipe having a length of 0 mm and a length of 8 m, the aqueous phase was removed by a centrifugal extractor to continuously obtain a methylene chloride solution of polycarbonate. In this case, the amount of phenylchloroformate was 1.4 times the mol of the terminal phenolic hydroxyl group of the polycarbonate.

The polycarbonate methylene chloride solution thus obtained is washed with 15% by volume of 0.2 N hydrochloric acid based on the methylene chloride solution of the polycarbonate, and then washed with 1% of the methylene chloride solution of the polycarbonate.
Electric conductivity after washing with 5% by volume of pure water is 10 μS / cm
Washing with pure water was repeated until the following was achieved. After washing, 20 parts of methylene chloride solution of polycarbonate
A volume% of acetone was added, followed by concentration and drying to obtain polycarbonate flakes. Table 2 shows the properties of the obtained polycarbonate flakes.

Example 2 Polycarbonate flakes were obtained in the same manner as in Example 1, except that phenyl chloroformate (b) shown in Table 1 was used instead of phenyl chloroformate (a). . Table 2 shows the properties of the obtained polycarbonate flakes.

Example 3 A polycarbonate flake was obtained in the same manner as in Example 1 except that phenyl chloroformate (c) shown in Table 1 was used instead of phenyl chloroformate (a). . Table 2 shows the properties of the obtained polycarbonate flakes.

Example 4 Polycarbonate flakes were obtained in the same manner as in Example 1, except that phenyl chloroformate (d) shown in Table 1 was used instead of phenyl chloroformate (a). . Table 2 shows the properties of the obtained polycarbonate flakes.

Comparative Example 1 Polycarbonate flakes were obtained in the same manner as in Example 1, except that phenylchloroformate (a) was not used. Table 2 shows the properties of the obtained polycarbonate flakes.

Comparative Example 2 Polycarbonate flakes were obtained in the same manner as in Example 1, except that phenyl chloroformate (e) shown in Table 1 was used instead of phenyl chloroformate (a). . Table 2 shows the properties of the obtained polycarbonate flakes.

[0039]

[Table 1]

[0040]

[Table 2]

The methods for measuring the properties described in Tables 1 and 2 are described below. (1) Phosgene content in phenyl chloroformate This quantification method is based on the reaction of phosgene with aniline and 1,3-
The determination was performed with reference to a quantification method based on a hygiene test method utilizing the production of diphenylurea. The details are shown below.
1.0 ml of the sample is placed in a sample boat (10 × 10 × 6
0 mm) and heated at 50 ° C. for 60 minutes while flowing nitrogen at 30 ml / min as a carrier gas. The carrier gas was passed through an absorption bottle containing 3 ml of the absorbing solution. After adjusting the volume of the absorbing solution to 10.0 ml with methanol, 1,3-diphenylurea contained in the absorbing solution was quantified by gas chromatography under the following conditions. The absorption liquid was dissolved by adding 100 ml of methanol to 0.25 g of distilled aniline, and further dissolved in water 5.
The pH was adjusted to 6 to 7 by adding 0 ml and hydrochloric acid.

<Conditions for Gas Chromatography> Column: DB-1 (15 m × 0.32 mmφ, membrane pressure;
0.1 μm) Column temperature: 180 ° C. Injection temperature: 280 ° C. Detection temperature: 430 ° C. Carrier gas: 40 kPa (split ratio; 20) Injection amount: 2.5 μl

(2) Color Tone of Phenylchloroformate Hazen standard colorimetric liquid numbers (APHA) 5 to 50 were prepared according to JIS K 2435 (1992), and the color tone of phenylchloroformate was visually evaluated.

(3) Amount of hydroxyl group in polycarbonate A 0.1 g sample was precisely weighed in a 25 ml volumetric flask and dissolved in about 5 ml of methylene chloride. Further, 10 ml of a titanium tetrachloride solution and 4 ml of an acetic acid solution were added, and the volume was adjusted to 25 ml with methylene chloride. The absorbance was measured at 480 nm (optical path length 10 nm) using UV-240 manufactured by Shimadzu Corporation. Similarly, a calibration curve was prepared using bisphenol A, and the OH group content was calculated from the absorbance of the sample solution. The above titanium tetrachloride solution was prepared by weighing 2.32 ml of titanium tetrachloride, adding 1.0 ml of acetic acid, and diluting it to 100 ml with methylene chloride. It was diluted to 100 milliliters.

(4) Amount of chloroformate Quantified by the method described in JP-A-4-266925. The details are shown below. 4- (4-nitrobenzyl)
1.0 g of pyridine was dissolved in methylene chloride to prepare a color developing solution having a constant volume of 100 milliliters. A sample solution (20 ml) was collected, and 2.0 ml of the prepared coloring solution was added thereto. After mixing well, the optical path length was 10 mm.
And the absorbance at 440 nm was measured by UV-240 manufactured by Shimadzu Corporation. Note that methylene chloride was used as a reference. Similarly, a calibration curve was prepared using phenyl chloroformate, and the amount of chloroformate was calculated as the chlorine concentration from the absorbance of the sample solution and the polycarbonate concentration.

(5) Initial color tone of polycarbonate (Y
I) 3.0 g of polycarbonate flake was mixed with methylene chloride 3
The solution was dissolved in 4.5 g, and the YI (yellow index) of this solution was measured with a color meter SM-3 (manufactured by Suga Test Instruments Co., Ltd.) using a quartz cell having an optical path length of 57 mm. The measured value and YI _a, was determined YI by the following equation. YI = 0.76 (YI _a −YI ₀ ) +0.11 (where YI ₀ is the YI _a value of methylene chloride)

(6) Heat resistance of polycarbonate (ΔY
I) 3.0 g of polycarbonate flakes were weighed in an aluminum boat and heated at 340 ° C. for 30 minutes in a nitrogen atmosphere. After cooling, it was dissolved in 34.5 g of methylene chloride. Remove the insolubles by filtration, the YI was measured as YI _b, was calculated ΔYI by the following equation. ΔYI = 0.76 (YI _b −YI _a )

(7) Insoluble Content 3.0 g of polycarbonate flakes were weighed in an aluminum boat and heated at 340 ° C. for 30 minutes in a nitrogen atmosphere. It is the amount of insolubles generated by dissolving in 34.5 g of methylene chloride after cooling.

[0049]

According to the present invention, it is possible to provide a method for producing a polycarbonate having sufficiently improved heat resistance by reacting a phenolic hydroxyl group in the polycarbonate with an arylchloroformate. The obtained polycarbonate is used in fields requiring more heat resistance depending on uses such as optical materials such as thin sheets and optical disks, and high-temperature high-speed injection molded products.

Continued on front page F-term (reference) 4J029 AA09 AB04 AC01 AD10 AE01 BB11A BB12A BB13A BD03A BD04A BD05A BD06A BD07A BD08 BD09A BF12 BF13 BF14A BH02 DB12 HA01 HC01 HC02 KE11 KH01

Claims (2)

[Claims] 1. A method for producing a polycarbonate by an interfacial polymerization method using phosgene and a dihydric phenol as main raw materials, wherein after separating an aqueous phase from a polymerization solution, the organic phase has a phosgene content of 150 ppm or less in the following general formula: (1) (Wherein, Ar represents a monovalent aromatic group.) An arylchloroformate represented by the following formula (1) is added in an equimolar to 2-fold molar amount with respect to the terminal phenolic hydroxyl group of the obtained polycarbonate. A method for producing a polycarbonate, comprising converting a hydroxyl group into an aryl carbonate group. 2. The process for producing a polycarbonate according to claim 1, wherein the arylchloroformate has an APHA of 30 or less.