JPH11158261A - Production of aromatic polycarbonate resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a high-quality arom. polycarbonate resin which is excellent in color tone and heat stability and does not cause the environmental problem due to methylene chloride. SOLUTION: In a process for producing an arom. polycarbonate resin by the transesterification of an aryl carbonate and an arom. dihydroxy compd., a catalyst contg. an alkali metal compd. and/or an alkaline earth metal compd. and a transition metal compd. is used as the transesterification catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aromatic polycarbonate resin. Specifically, to produce a high-molecular-weight aromatic polycarbonate resin with low coloring, particularly excellent heat resistance, moisture resistance and weather resistance, and good flowability easily and highly productively by transesterification, and industrially. About.

[0002]

2. Description of the Related Art Aromatic polycarbonate resins are widely used as engineering plastics in applications utilizing their impact resistance, dimensional stability, and transparency.
As the industrial production method, a phosgene method (interfacial polymerization method), a transesterification method (melt polymerization method), and the like are known.

[0003] The former phosgene method is widely used industrially, but in this method, harmful phosgene is used, and the produced aromatic polycarbonate resin is used in a large amount as a solvent. There is a problem of environmental pollution due to emission of methylene chloride into the atmosphere. Furthermore,
Since the aromatic polycarbonate resin obtained by this method has a high affinity for methylene chloride, it is difficult to completely remove methylene chloride from the resin. There have been problems such as generation of hydrogen gas to corrode the molding machine and deterioration of the polymer.

[0004] On the other hand, the latter transesterification method does not require the use of phosgene, has no risk of environmental pollution by a halogen-containing solvent such as methylene chloride, and can obtain a chlorine-free polymer. It is considered more preferable. However, in the method for producing an aromatic polycarbonate resin by this method, since the viscosity of the polymer becomes extremely high in the latter stage of the reaction, it is necessary to increase the reaction temperature in order to obtain a high molecular weight aromatic polycarbonate resin, while the phenol produced Since it is essential to remove the compounds, a special reactor is required for performing the transesterification at a high degree of vacuum. Therefore, in the conventional method, elution of metal from the surface of a metal such as stainless steel used as a material of the reactor,
Due to the catalyst itself, there is a problem that the obtained resin is easily colored by a side reaction due to heat, and is inferior in thermal stability.

[0005]

The coloring of the aromatic polycarbonate is mainly attributable to the following two points. First, it has been suggested that the material of the reactor, especially iron, affects the coloration.
Therefore, according to U.S. Pat. No. 4,383,092, it is proposed to prevent the coloring of the aromatic polycarbonate by lining the liquid contact part of the reactor with glass or tantalum, nickel or chromium.
On the other hand, Japanese Patent Application Laid-Open No. 4-332726 discloses that a material having an iron component of 20% or less is used for a liquid contact part of a reactor. However, these metal materials and surface treatment methods are not substantial because they are expensive for use in a reactor.

Second, bisphenols used as monomers and phenols produced as by-products have low thermal stability.
Therefore, a substance which causes coloring of the polymer is easily generated during the reaction. However, if the reaction temperature is lowered in order to suppress these thermal decomposition reactions, it takes a long time for the polymerization reaction, so that it has been difficult to obtain a high molecular weight aromatic polycarbonate resin. In view of this, Japanese Patent Application Laid-Open No. 2-124934 proposes to use a nitrogen-containing basic compound and an alkali metal or alkaline earth metal as a catalyst, but it is still insufficient to make the polymer completely colorless. Was. Further, when an alkali metal or alkaline earth metal is used alone as a catalyst, not only the color tone of the polymer but also the thermal stability, particularly the color tone stability during melt retention, and the hydrolysis resistance at high temperatures are inferior. There is a drawback that the fluidity is inferior because branching is likely to occur.

[0007]

Means for Solving the Problems The present inventors have found that an aromatic polycarbonate resin having a reduced chlorine atom content and a suppressed coloration, and particularly excellent in heat stability, can be produced at a high productivity by a transesterification method. As a result of intensive studies to produce in the present invention, during the production of aromatic polycarbonate resin, it has been found that the above problem can be solved by using a catalyst consisting of a specific combination as a transesterification catalyst, and the present invention has been achieved. .

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
As the aromatic dihydroxy compound used as a raw material,
What is represented by the following general formula (I) is used.

[0009]

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Wherein R ¹ and R ² are each independently a hydrogen atom,
A nitro group, an alkyl group or an aryl group which may have a substituent; As the alkyl group, a linear or branched alkyl group having 1 to 4 carbon atoms such as methyl and ethyl is preferable, and a methyl group is more preferable. As the aryl group, phenyl, naphthyl, other alkyl-substituted phenyl groups, and more preferably a phenyl group are preferred. These alkyl groups or aryl groups may have a substituent such as a halogen or a nitro group. X ² is a single bond, methylene, 1,
1-ethylene, 1,2-ethylene, 2,2-propylene, linear or cyclic alkylene group such as 1,1-cyclohexylene or -O, -, - S -, - SO -, - SO 2
And a divalent functional group such as-or -CO-.

Of these, particularly preferred are 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl)
Ethane, 1,1-bis (4-hydroxyphenyl) butane, 1,1-bis (4-hydroxyphenyl) pentane, 2,2-bis (4-hydroxyphenyl) pentane, 3,3-bis (4-hydroxy Phenyl) pentane, 2,2-bis (3-methyl-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenyl sulfide , 4,4'-dihydroxydiphenylsulfoxide, 4,4'-dihydroxydiphenylsulfone, and the like. These aromatic dihydroxy compounds may be used alone or as a mixture. Of these, 2,2-bis (4-hydroxyphenyl) propane is preferred.

The aryl carbonates in the present invention are compounds represented by the general formula (II), and include not only diaryl carbonates but also condensates such as polycarbonate oligomers.

[0013]

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In the formula, R ^{3 to} R ⁶ each independently represent a halogen such as fluorine, chlorine or bromine, a nitro group or a substituent, preferably an alkyl group having 1 to 6 carbon atoms, or an aryl group. Represents a group. J represents an integer of 0 to 20. Among these, specific examples of diaryl carbonates include diphenyl carbonate, bis (p-chlorophenyl) carbonate, bis (p-nitrophenyl) carbonate, and the like. Examples of the polycarbonate oligomer include bisaryl carbonate of bisphenol A. Of these, diphenyl carbonate is particularly preferred.

In order to produce the aromatic polycarbonate used in the present invention by a transesterification reaction, in order to supplement the distillation of the bisaryl carbonate during the polymerization, the aryl carbonate is converted into an aromatic dihydroxy compound with respect to the aromatic dihydroxy compound. It is used in a molar ratio of 1 to 2 times, preferably 1.02 to 1.5 times. As the polymerization catalyst in the present invention, a catalyst system comprising two components of an alkali metal and / or alkaline earth metal compound and a transition metal compound is used. Among the combinations of these metal catalysts, a combination of an alkali metal and a transition metal compound belonging to Group 3 to 6 is preferable. Specific examples of the alkali metal include lithium, sodium, potassium, rubidium, and cesium. Of these, sodium and potassium are particularly preferred.

The type of the metal compound is not particularly limited, but a basic compound is preferred in terms of catalytic activity. Specifically, oxides, hydroxides, carbonates, amides, phosphates, sulfides of the above metals, and salts of organic acids, for example, various fatty acid salts such as acetate, benzoate, etc. And aromatic carboxylate. Of these, basic inorganic compounds such as hydroxides and carbonates are particularly preferred. Further, among the transition metals, a compound of a rare earth metal or a metal belonging to Group 4 is particularly preferable in terms of catalytic activity and physical properties of the obtained polymer.

Specific examples of rare earth metals include scandium, yttrium, lanthanum, and metals belonging to lanthanoids, ie, cerium, praseodymium, neodymium,
Samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium. Of these, lanthanum and cerium are preferred, and lanthanum is particularly preferred. There is no particular limitation on the types of these metal compounds, and specific examples of the compound include hydroxides of the above metals,
Oxides, carbonates, alkoxides, phenoxides, and salts of organic acids, for example, various fatty acid salts such as acetate, aromatic carboxylate such as benzoate, and coordination such as acetylacetone and ethylenediaminetetraacetic acid And a chelate compound with the same.

Further, as a metal belonging to Group 4 specifically,
Include titanium, zirconium, hafnium, etc.
You. Of these, titanium is particularly preferred. These metals
There is no particular limitation on the type of the compound of
Typically, oxides, alkoxides, phenoxy of the above metals
Chelation with ligands such as acetylacetone
Organometallic compounds such as compounds, alkylated compounds and metallocenes
Objects and the like. The addition amount of these metal compound catalysts
Of aromatic diphenols such as bisphenol
Metal amount conversion for 1 mol of droxy compound
At 1 × 10 ^-Five~ 1 × 10^-8mol is preferred, particularly preferred
Or 1 × 10^-Five~ 1 × 10^-7mol.

Further, in addition to the above-mentioned combination of metal catalysts, a co-catalyst can be used if necessary.
The cocatalyst referred to here is not particularly limited as long as it is a basic compound, but preferred are amines such as triethylamine, substituted and unsubstituted pyridines, and quaternary ammonium compounds such as tetramethylammonium hydroxide.
Organic compounds containing nitrogen or phosphorus, such as quaternary phosphonium compounds such as tetramethylphosphonium hydroxide, and the like can be mentioned. Among these, a basic quaternary ammonium compound or a basic quaternary phosphonium compound is particularly preferable.

Here, specific examples of the basic quaternary ammonium compound include hydroxides and carbonates of tetraalkyl / aryl ammoniums such as tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium and tetraphenylammonium. , Phosphates, borates, and various carboxylate salts. Further, specific examples of the basic quaternary phosphonium compound include tetramethylphosphonium,
Examples include hydroxides, carbonates, phosphates, borates, and various carboxylate salts of tetraalkyl / aryl phosphonium such as tetraethylphosphonium, tetrapropylphosphonium, tetrabutylphosphonium, and tetraphenylphosphonium.

Among these basic quaternary ammonium compounds and basic quaternary phosphonium compounds, hydroxides, carbonates and borates are particularly preferred, and hydroxides are more preferred. The amount of these cocatalysts added was 1 × 1 with respect to 1 mol of the aromatic dihydroxy compound used.
0 ^-2 to 1 × 10 ^-6 mol, preferably 1 × 10 ^-4 to 1 × 1
0 ^-6 mol.

If the amount of the above-mentioned catalyst and co-catalyst is less than this range, the effect as a catalyst may be low, which is not preferable. Conversely, even if the amount added is greater than this range,
This does not provide a special effect, which is not only economically disadvantageous but also may have a detrimental effect on coloring, heat stability, hydrolysis resistance and the like.
The method of adding these catalysts and cocatalysts is not particularly limited,
A plurality of catalysts and cocatalysts can be added in the same solution or separately.

In the method for producing an aromatic polycarbonate resin of the present invention, a polycarbonate resin can be produced by a one-step reaction in a tank reactor, but particularly when a high molecular weight polycarbonate resin is to be produced, The transesterification reaction is carried out in a pre-polycondensation step and a post-polycondensation step.In the pre-polycondensation step, a prepolymer having a low melt viscosity is produced using a tank reactor, and the prepolymer is further raised in the post-polycondensation step. Preferably, the molecular weight is reduced. In the post-polycondensation step, a production method having a small heat history is preferable. As an example of such a production step,
Examples include a method using a horizontal two-axis self-cleaning type high-viscosity reactor and a solid-phase polymerization method. In particular, a method using a horizontal two-axis self-cleaning high-viscosity reactor is preferable.

The reaction temperature in the pre-polycondensation step is such that the amount of phenol distilled out of the reaction system is 0.80 to 1.20 mol per 1 mol of the bisphenol compound used, Is performed at a temperature of 220 ° C. or lower, and then gradually heated to 250 ° C. to 3
The temperature is preferably set to 20 ° C., particularly 260 ° C. to 300 ° C. The pressure ranges from normal pressure to 0.1 mmHg. In this step, the viscosity average molecular weight is 1,000 to 2
An aromatic polycarbonate prepolymer of 000 is obtained. At this time, the molecular weight of the prepolymer is
When it is lower than 0, it takes a long time to increase the molecular weight in the post-polycondensation step, which is disadvantageous in terms of productivity. When the molecular weight of the prepolymer exceeds 20,000, it is necessary to carry out a pre-polycondensation reaction at a high temperature of 300 ° C. or more in order to prevent the melt viscosity from increasing when producing in a tank reactor. This is disadvantageous in that the polymer is colored. On the other hand, in the case of further increasing the molecular weight using a horizontal twin-screw self-cleaning high-viscosity reactor in the post-polycondensation step, the prepolymer obtained in the first step may be directly fed to the reactor in a molten state. The pelletized material may be melted again by an extruder or the like and then fed.

The horizontal two-axis self-cleaning high-viscosity reactor used in the present invention has two horizontal rotating shafts rotating in the same direction and a rotating shaft that rotates in a direction perpendicular to the horizontal rotating shaft. With a stirring plate attached to the The phases of the respective stirring plates are shifted from each other, and the resins attached to the stirring plates are stirred without stagnation because they rotate while maintaining a slight clearance therebetween, and the surface is renewed (self-cleaning property). The cross-sectional shape of the stirring plate includes a disk type, a hollow disk type, a convex lens type, a rod type, a window frame type, a pseudo triangular type, and the like, but is not necessarily limited to these in the present invention. is not.

The reaction temperature in the post-polycondensation step is as follows:
240 ° C. to 350 ° C., preferably 250 ° C. to 300 ° C., and a pressure of 10 mmHg or less, preferably 2 mmHg
It is as follows. In addition, the horizontal reaction apparatus in the present invention has a larger internal volume than a screw-type twin-screw extruder, and the extrusion performance of the resin can be controlled by the shape and the mounting position of the stirring plate. It is possible to take a long time. Usually, the residence time is between 10 minutes and 90 minutes, preferably between 15 minutes and 60 minutes. The viscosity average molecular weight of the aromatic polycarbonate resin obtained after the reaction using a horizontal reactor in the polycondensation step is 15,000 to 60,000.

The material of the portion of the reactor that comes into contact with the reaction mixture is not particularly limited, but a metal or alloy having an iron content of 25% by weight or more, such as stainless steel such as SUS316, can be used. If necessary, other known transesterification catalysts can be added within the scope of the present invention. Alternatively, a known thermal compound such as a phosphite compound, a phosphonic acid compound, or a hindered phenol compound may be added simultaneously with the aromatic dihydroxy compound or the carbonate precursor as a monomer, or during or after the pre / post-polycondensation reaction step. By using additives such as stabilizers, it is also possible to improve the thermal stability of the resulting aromatic polycarbonate resin.

Further, the physical properties and the like can be improved by adding an inorganic filler or the like in exactly the same manner,
By adding a branching agent such as a trihydric or higher polyhydric phenol and a derivative thereof, the aromatic polycarbonate resin has a branched structure to improve its melt fluidity, and to improve the melt fluidity of terephthalic acid and isophthalic acid. It is also possible to add a dicarboxylic acid or a derivative thereof to improve the chemical resistance and the like as an aromatic polyester carbonate.

The aromatic polycarbonate resin produced by the method of the present invention is excellent in color tone and thermal stability, and has little decrease in molecular weight and mechanical properties after molding. Therefore, the polycarbonate resin can be widely used as a general engineering plastic, and is extremely advantageous industrially.

[0030]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which, however, are not intended to limit the scope of the invention. (1) Viscosity average molecular weight (Mv): a value obtained by measuring the intrinsic viscosity [η] (dL / g) of a methylene chloride solution at 20 ° C. using an Ubbelohde viscosity tube and calculating using the following equation.

[0031]

[Η] = 1.23 × 10 ^-4 · (Mv) ^0.83

(2) Heat treatment of polymer (high-temperature residence test): 4 g of polymer (no additives such as heat stabilizer, antioxidant, catalyst deactivator, etc.) are put into a test tube, and aluminum is passed under nitrogen flow. Heat treatment was performed at 360 ° C. for 1 hour using a block bath. (3) Color tone of polymer (YI value): 25 g of 4 g of polymer
A value obtained by placing a solution dissolved in ml of methylene chloride in a cell having an optical path length of 1 cm, and using a color computer (SM Color Computer, manufactured by Suga Test Instruments Co., Ltd., model SM-4) by a transmission method. Table 1 shows the change in YI (ΔYI) before and after the heat treatment for the polymers produced in the following examples.

(4) Polymerization of polycarbonate <Preparation of catalyst>
0 μmol (1 μm per 1 mol of bisphenol A)
ol) in 5 ml of water, and 2 μmol of a transition metal compound in terms of metal amount (1 mol of bisphenol A)
0.1 μmol) to 5 ml of water or methanol
Were mixed with each other to prepare a catalyst solution (suspension).

<Polymerization> 4566 g of bisphenol A
(20.0 mol), diphenyl carbonate 4584
g (21.4 mol) in a 30-liter tank reactor (S
US316L) and 0.5 mmol of tetramethylammonium hydroxide (2 mol per mol of bisphenol A) when using the above catalyst solution and further using a cocatalyst.
After adding an aqueous solution containing 5 μmol), the atmosphere is replaced with nitrogen,
The temperature gradually increased. Stirring was started after the reaction mixture was dissolved, and the time when the internal temperature reached 170 ° C. was defined as the polymerization start time. Then raise the temperature while gradually reducing the pressure,
At the beginning of the reaction, the temperature is kept at 100 mmHg and 210 ° C. for a while until the amount of phenol produced reaches 22 mol (1.1 mol per 1 mol of bisphenol A), and then the pressure inside the reaction vessel is gradually reduced and the temperature is raised to 1 mmHg.
A condensation reaction was carried out at 70 ° C., and subsequently the phenol produced was distilled off, and the polymerization was completed in a total polymerization time of 3 to 4 hours.
After re-pressurizing the inside of the tank, it was extruded into a water tank in a strand shape and pelletized by a cutter.

Next, as a post-polymerization step, the prepolymer was melted at 270 ° C. with a twin-screw extruder, and a twin-screw self-cleaning high-viscosity reactor (internal volume 2 L, vacuum degree 0.2 mmH
g, rotation speed 30 rpm) and extracted with a screw. The residence time was 30 minutes.

Example 1 Sodium carbonate as an alkali metal compound as a catalyst,
Using lanthanum hydroxide as the transition metal compound,
A polycarbonate was obtained by the above polymerization method. Table 1 shows the results. Example 2 Tetramethylammonium hydroxide (TMA) as co-catalyst
H), and the addition amount of sodium carbonate was 2 μmol (bisphenol A
The procedure was performed in the same manner as in Example 1 except that the amount was reduced to 0.1 μmol per 1 mol). Table 1 shows the results.

Example 3 The procedure of Example 1 was repeated except that lanthanum acetate was used instead of lanthanum hydroxide as the transition metal compound. Table 1 shows the results. Example 4 It carried out like Example 1 except having used lanthanum acetylacetonate instead of lanthanum hydroxide as a transition metal compound. Table 1 shows the results.

Example 5 The procedure of Example 1 was repeated, except that sodium hydroxide was used instead of sodium carbonate as the alkali metal compound. Table 1 shows the results. Example 6 It carried out like Example 1 except having used titanium oxide acetylacetonate instead of lanthanum hydroxide as a transition metal compound. Table 1 shows the results.

Example 7 The procedure of Example 2 was repeated except that titanium oxide acetylacetonate was used instead of lanthanum hydroxide as the transition metal compound. Table 1 shows the results. Example 8 It carried out like Example 1 except having used tetrabutoxytitanium instead of lanthanum hydroxide as a transition metal compound. Table 1 shows the results.

Example 9 The procedure of Example 6 was repeated, except that sodium hydroxide was used instead of sodium carbonate as the alkali metal compound. Table 1 shows the results.

Comparative Example 1 The procedure of Example 1 was repeated except that lanthanum hydroxide was not used. Table 1 shows the results. Comparative example 2 It carried out similarly to Example 2 except not using sodium carbonate. Table 1 shows the results.

Comparative Example 3 The same operation as in Example 7 was carried out except that sodium carbonate was not used. Table 1 shows the results. Comparative example 4 It carried out like Example 2 except not using lanthanum hydroxide. Table 1 shows the results.

[0043]

[Table 1]

[0044]

According to the process for producing an aromatic polycarbonate resin according to the present invention, there is no environmental problem due to methylene chloride, and a high quality aromatic polycarbonate resin excellent in color tone and heat stability can be easily and highly produced. It can be manufactured by The aromatic polycarbonate resin obtained by the present application can be used for a wide range of applications including optical materials. In addition, optical materials such as compact discs, optical discs, and connectors that require high purity, medical and food applications that require safety, and glass covers such as lens covers and sheets that require long-term reliability. It is a polycarbonate resin that can be easily produced by a wide range of molding methods such as injection, extrusion, and blow molding.

Claims (16)

[Claims] 1. A method for producing an aromatic polycarbonate resin by a transesterification reaction between an aryl carbonate and an aromatic dihydroxy compound, wherein the transesterification catalyst comprises an alkali metal and / or alkaline earth metal compound; A method for producing an aromatic polycarbonate resin, comprising using a catalyst containing: 2. The method for producing an aromatic polycarbonate resin according to claim 1, wherein the transition metal is a transition metal belonging to Groups 3 to 6. 3. The method for producing an aromatic polycarbonate resin according to claim 1, wherein the alkali metal is sodium or potassium. 4. The method for producing an aromatic polycarbonate resin according to claim 1, wherein the alkali metal is sodium. 5. The method for producing an aromatic polycarbonate resin according to claim 1, wherein the transition metal is a rare earth metal. 6. The method for producing an aromatic polycarbonate resin according to claim 5, wherein the rare earth metal belongs to a lanthanoid. 7. The method for producing an aromatic polycarbonate resin according to claim 6, wherein the rare earth metal is lanthanum or cerium. 8. The method for producing an aromatic polycarbonate resin according to claim 7, wherein the rare earth metal is lanthanum. 9. The method for producing an aromatic polycarbonate resin according to claim 1, wherein the transition metal belongs to Group 4. 10. The method for producing an aromatic polycarbonate resin according to claim 9, wherein the transition metal is titanium. 11. The amount of the alkali metal and / or alkaline earth metal compound used in the aromatic dihydroxy compound 1
1 × 10 ^-5 to 1 × 10 ^-8 m in terms of metal amount based on mol
The method for producing an aromatic polycarbonate resin according to any one of claims 1 to 10, wherein 12. The amount of the transition metal compound to be used is 1 × 10 5 in terms of the amount of metal per 1 mol of the aromatic dihydroxy compound.
^{2. The composition according} to claim 1, wherein the amount is from ^-5 to 1 × 10 ^-8 mol.
13. The method for producing an aromatic polycarbonate resin according to any one of items 11 to 11. 13. The method for producing an aromatic polycarbonate resin according to claim 1, wherein a basic compound is further used as a catalyst. 14. The method for producing an aromatic polycarbonate resin according to claim 13, wherein an organic compound containing nitrogen and / or phosphorus is used as the basic compound. 15. The method for producing an aromatic polycarbonate resin according to claim 13, wherein the basic compound is a quaternary ammonium compound and / or a quaternary phosphonium compound. 16. The amount of the basic compound used is 1 × 10 ⁻² to 1 × 10 ^{−6 with} respect to 1 mol of the aromatic dihydroxy compound.
The method for producing an aromatic polycarbonate resin according to any one of claims 13 to 15, wherein the amount is mol.