JPH1045894A - Production of polycarbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient production process for a high-quality polycarbonate which has good color tone with reduced deterioration caused by heat and/or under high-temperature and high-humidity environments, shows reduced discoloration and stay burning, thus is useful as an optical material. SOLUTION: In this production process for polycarbonate, the preparation of polycarbonate prepolymer by the preliminary polymerization is followed by the main polymerization in the solid state or in the swollen solid state in the presence of a catalyst of a trivalent or pentavalent phosphorus compound or a nitrogen-containing organic basic compound. The polycarbonate produced according to this process is useful as an optical material.

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 a polycarbonate, and more particularly, to a method for efficiently producing a polycarbonate having excellent quality by polymerizing a polycarbonate prepolymer in a solid state or a swollen solid state. It is about. Further, the present invention relates to a polycarbonate for an optical material obtained by such a method.

[0002]

2. Description of the Related Art Polycarbonate can be produced by directly reacting an aromatic dihydroxy compound such as bisphenol A with phosgene (interfacial method) or by melting an aromatic dihydroxy compound such as bisphenol A and a diester carbonate such as diphenyl carbonate. A method of performing a transesterification reaction (melting method / solid phase method) in a solid state or a solid state is known.

[0003] The interface method has disadvantages such as the use of toxic phosgene and the corrosion of the apparatus by a by-product chlorine-containing compound. On the other hand, in the melting method, usually 280
In order to react for a long time under high temperature of ℃ ~ 310 ℃,
There were problems such as the inevitable coloring of the obtained polycarbonate and the inability to obtain a high molecular weight product. Further, there is a problem that a basic catalyst is often used, and the obtained polymer has poor hydrolysis resistance.

In order to solve these problems in the melting method, various improved methods have been proposed, such as a method using a specific catalyst and a method of adding an antioxidant at a later stage of the polymerization reaction. The problems of quality deterioration and coloring in a high-temperature and high-humidity environment have not been solved yet, and satisfactory products in terms of staying burn and color tone have not yet been obtained. Especially as polycarbonate for optical materials,
At present, a material having sufficient performance has not yet been obtained.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the conventional method for producing a polycarbonate and to provide a method for efficiently producing a polycarbonate having excellent quality. Things. Also,
It is an object of the present invention to provide a polycarbonate excellent for optical materials.

[0006]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has prepared a polycarbonate prepolymer (hereinafter sometimes abbreviated as "prepolymer"). When polymerizing the prepolymer in a solid state or a swollen solid state, it has been found that by using a specific compound as a catalyst, a polycarbonate having excellent quality can be efficiently produced and the above object can be achieved. . The present invention has been completed based on such findings.

That is, the present invention provides (1) a method of preparing a polycarbonate prepolymer by prepolymerization and then swelling the prepolymer in a solid state or swelling with a trivalent or pentavalent phosphorus compound or a nitrogen-containing organic basic compound as a catalyst. An object of the present invention is to provide a method for producing a polycarbonate obtained by polymerizing in a solid state. Further, (2) the present invention provides a polycarbonate for an optical material obtained by the method described in the above (1).

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The raw material for producing polycarbonate in the present invention is not particularly limited, but (A) a dihydroxy compound and (B) a carbonic acid diester or phosgene can be preferably used. Alternatively, a branching agent or the like is used in combination. Using these raw materials,
A prepolymer is prepared by pre-polymerization, and after that, the crystallized prepolymer is polymerized in a solid state or a swollen solid state to produce a polycarbonate.

As the catalyst, a nitrogen-containing organic basic compound is preferably used at the time of prepolymerization, but at the time of polymerization in a solid state or a swollen solid state, a trivalent or pentavalent phosphorus compound or a nitrogen-containing base is used. It is necessary to use an acidic compound. (1) Raw material (A) Dihydroxy compound For example, an aromatic dihydroxy compound and an aliphatic dihydroxy compound are mentioned, and at least one compound selected from these is used.

The aromatic dihydroxy compound used as one of the components (A) is represented by the general formula (I)

[0011]

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The compounds represented by the following formulas can be mentioned.
In the general formula (I), R ¹ and R ² each represent a halogen atom of fluorine, chlorine, bromine, or iodine or an alkyl group having 1 to 8 carbon atoms, for example, a methyl group, an ethyl group, an n-
Propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, pentyl,
It represents a hexyl group, a cyclohexyl group, a hebutyl group, an octyl group, or the like. R ¹ and R ² may be the same or different. The plurality of R ¹ is when R ¹ are a plurality may be the same or different, a plurality of R ² if R ² there are a plurality may be the same or different. m and n are each an integer of 0-4. Z is a single bond, an alkylene group having 1 to 8 carbon atoms, an alkylidene group having 2 to 8 carbon atoms, a cycloalkylene group having 5 to 15 carbon atoms, a cycloalkylidene group having 5 to 15 carbon atoms, or -S-, −
SO—, —SO ₂ —, —O—, —CO— bond or formula (II), (II ′)

[0013]

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[0014] The bond represented by Examples of the alkylene group having 1 to 8 carbon atoms and the alkylidene group having 2 to 8 carbon atoms include:
Examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, an ethylidene group, an isopropylidene group and the like. As a cycloalkylene group having 5 to 15 carbon atoms and a cycloalkylidene group having 5 to 15 carbon atoms, Examples thereof include a cyclopentylene group, a cyclohexylene group, a cyclopentylidene group, and a cyclohexylidene group.

In a preferred production method of the present invention,
As the dihydroxy compound of the component (A), one or more of the above compounds are appropriately selected and used, and among these, bisphenol A which is an aromatic dihydroxy compound is preferably used. Further, diesters of dihydroxy compounds, dicarbonates of dihydroxy compounds, monocarbonates of dihydroxy compounds, and the like can also be used.

Component (B) Various carbonic acid diesters are used. For example, it is at least one compound selected from diaryl carbonate compounds, dialkyl carbonate compounds and alkylaryl carbonate compounds.

The diaryl carbonate compound used as one of the components (B) has the general formula (III)

[0018]

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Wherein Ar ¹ and Ar ² each represent an aryl group, which may be the same or different, or a compound of the general formula (IV)

[0020]

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(Wherein, Ar ³ and Ar ⁴ each represent an aryl group, which may be the same or different, and D ¹ represents two hydroxyl groups from the aromatic dihydroxy compound of the above general formula (I). The residue is shown as an excluding residue.). The dialkyl carbonate compound is represented by the general formula (V)

[0022]

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(Wherein R ³ and R ⁴ each have 1 carbon atom)
Represents an alkyl group having from 6 to 6 or a cycloalkyl group having from 4 to 7 carbon atoms, which may be the same or different. Or a compound represented by the general formula (VI)

[0024]

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Wherein R ⁵ and R ⁶ each have 1 carbon atom
And a cycloalkyl group having 4 to 7 carbon atoms, which may be the same or different, and D ² represents a hydroxyl group 2 from the aromatic dihydroxy compound.
The residue excluding the number is shown. ). The alkylaryl carbonate compound is represented by the general formula (VII)

[0026]

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(Wherein, Ar ⁵ represents an aryl group, R ⁷ represents an alkyl group having 1 to 6 carbon atoms or a cycloalkyl group having 47 carbon atoms), or a compound represented by the general formula (VIII)

[0028]

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(Wherein, Ar ⁶ is an aryl group, R ⁸ is an alkyl group having 1 to 6 carbon atoms or a cycloalkyl group having 4 to 7 carbon atoms, and D ³ is a group obtained by removing two hydroxyl groups from the aromatic dihydroxy compound. The compound is a compound represented by the following formula:
As the carbonic acid diester of the component (B), one or more of the above compounds are appropriately selected and used, and among these, diphenyl carbonate is preferably used.

Phosgene It is also possible to use phosgene as the component (B). In this case, it is necessary to use an appropriate amount of the monohydroxy compound. (2) Preparation of Prepolymer by Prepolymerization In the prepolymerization, the dihydroxy compound of component (A) and the carbonic acid diester or phosgene of component (B) are used as raw materials, and if necessary, a terminal terminator or a branching agent is used. , Prepare a prepolymer. In this case, it is preferable to use a nitrogen-containing organic basic compound as the polymerization catalyst.

Specific preferred procedures and conditions of the production method will be described. Method of Prepolymerization (i) A prepolymer can be prepared by treating a dihydroxydiaryl compound and a diarylcarbonate with heating to remove an aromatic monohydroxy compound. The weight average molecular weight of the prepolymer produced in this prepolymerization step is preferably 2000
It is selected in the range of ２０20,000. This prepolymerization reaction,
It is preferably carried out in the molten state.

The ratio of the diaryl carbonate and the dihydroxydiaryl compound to be used (the charge ratio) varies depending on the kind used, the reaction temperature and the reaction conditions, but the diaryl carbonate is used per mole of the dihydroxydiaryl compound. And usually used in a ratio of 0.9 to 2.5 mol. The reaction temperature and reaction time vary depending on the type and amount of the raw materials and catalyst used, the required polymerization amount of the obtained prepolymer, other reaction conditions, and the like, but are preferably at a temperature of 50 to 350 ° C, preferably 1 minute to 100 Selected within a time range. In order not to color the prepolymer, it is desirable to carry out the prepolymerization reaction at a temperature as low as possible and in a short time. The pressure during the reaction is preferably 1 To
rr〜5 kg / cm ² G.

The terminal ratio of the prepolymer produced by this step is preferably in the range of phenyl carbonate terminal: hydroxyl terminal = 1: 4 to 4: 1. (Ii) A prepolymer can also be prepared by a known method in which an aromatic dihydroxy compound and phosgene are reacted in the presence of the above-mentioned molecular weight regulator, acid binder and solvent.

Catalyst for Prepolymerization As a catalyst, a nitrogen-containing organic basic compound described later is used.
Is preferred. In the present invention, it is a raw material
The polymerization is carried out with respect to 1 mol of the dihydroxy compound of the component (A).
As a catalyst, a nitrogen-containing organic basic compound is preferably used.
^-2-10^-8Mole, more preferably 10^-3-10^-7For mole
Is desirable. When the amount of nitrogen-containing organic basic compound used is
10^-8If the amount is less than the mole, the catalyst activity in the initial stage of the reaction becomes insufficient.
10 ^-2Exceeding moles leads to increased costs and is good
Not good.

Crystallization of Prepolymer Preferably, the prepolymer is crystallized, but the method is not particularly limited, and a solvent treatment method and a heat crystallization method are preferably used. (3) Production of Polycarbonate by Polymerization In the present invention, after preparing a polycarbonate prepolymer, the tripolymer or pentavalent phosphorus compound or a nitrogen-containing organic basic compound is used as a polymerization catalyst to convert the prepolymer into a solid state. Alternatively, the polymerization is carried out in a swollen solid phase.

Trivalent phosphorus compound The trivalent phosphorus compound is not particularly limited, and includes various compounds. For example, the general formula (X) or (XI) R ¹⁰ ₃ P (X The compound represented by (R ¹⁰ O) ₃ P (XI) is used.

In the above general formula (X) or (XI), R ¹⁰
Represents a hydrogen atom or an organic group. Examples of the organic group include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group and a cyclohexyl group, a cycloalkyl group, and a phenyl group. , A tolyl group, a naphthyl group, an aryl group such as a biphenyl group, and an arylalkyl group such as a benzyl group. Three R ¹⁰ may be the same with or different from each other, or may form two R ¹⁰ are bonded to the ring structure.

Among such trivalent phosphorus compounds, compounds represented by the general formula (X) include, for example, ethyl phosphine, diethyl phosphine, propyl phosphine, dipropyl phosphine, diisoamyl phosphine, triethyl phosphine, triethyl phosphine and triethyl phosphine. Alkyl phosphines such as -n-propyl phosphine, triisopropyl phosphine, tri-n-butyl phosphine, phenyl phosphine, diphenyl phosphine, phenyl methyl phosphine, phenyl dimethyl phosphine, triphenyl phosphine, tri-p-tolyl phosphine, tri-o Aryl phosphines such as -tolyl phosphine, tris (2,4-di-t-butylphenyl) phosphine, tris (p-methoxyphenyl) phosphine, or aryl alkyl phosphines. Examples of the compound represented by the general formula (XI) include dimethyl phosphite, trimethyl phosphite, diethyl phosphite, triethyl phosphite, dibutyl phosphite, tributyl phosphite, dipropyl phosphite, and tripropyl phosphite. , Dipentyl phosphite, tripentyl phosphite, dinonyl phosphite, trinonyl phosphite, didecyl phosphite, tridecyl phosphite,
Alkyl phosphites such as dioctadecyl phosphite and trioctadecyl phosphite, diphenyl phosphite, triphenyl phosphite, tris (ethylphenyl) phosphite, tris (2,4-di-t-
Aryl phosphites such as butylphenyl) phosphite, tris (nonylphenyl) phosphite and tris (hydroxyphenyl) phosphite, diphenyloctyl phosphite, diphenyldecyl phosphite, phenyldidecyl phosphite, and 4,4′- Butylidene-bis (3-methyl-6-t-butylphenyl-ditridecyl) phosphite, 1,1,3-tris (2-
Arylalkyl phosphites such as methyl-4-ditridecylphosphite-5-t-butylphenyl) butane and 4,4′-isopropylidene-diphenolalkyl phosphite.

Pentavalent Phosphorus Compound The pentavalent phosphorus compound is not particularly limited and includes various compounds. For example, general formula (XII) or (XIII) R ¹¹ P = O (XII) The compound represented by (R ¹¹ O) ₃ P = O (XIII) is used.

In the above general formula (XII) or (XIII),
R¹¹Represents a hydrogen atom or an organic group.
Is, for example, methyl, ethyl, propyl, butyl
Group, pentyl group, hexyl group, octyl group, cyclohexyl
Alkyl group such as sil group, cycloalkyl group, phenyl
Aryl, tolyl, naphthyl, biphenyl, etc.
And arylalkyl groups such as benzyl group.
Can be Three R ¹¹Same but different
And two R¹¹Combine to form a ring structure
It may be.

Among such pentavalent phosphorus compounds, compounds represented by the general formula (XII) include, for example, triethyl phosphate, tri-n-propyl phosphate, triisopropyl phosphate, tri-n-butyl phosphate, Examples of the phosphoric esters such as triphenyl phosphate, tri-p-tolyl phosphate, and tri-o-tolyl phosphate, and the compounds represented by the general formula (XIII) include, for example, triethyl phosphine oxide, tri-n-propyl phosphine oxide And phosphine oxides such as triisopropylphosphine oxide, tri-n-butylphosphine oxide, triphenylphosphine oxide, tri-p-tolylphosphine oxide, and tri-o-tolylphosphine oxide. In addition, methyl acid phosphate,
Ethyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, 2-ethylhexyl acid phosphate, isodecyl acid phosphate, lauryl acid phosphate, tridecyl acid phosphate, stearyl acid phosphate, oleyl acid phosphate, phenyl acid phosphate, tolyl acid t-phosphate Phosphate esters (aryl acid phosphates) such as butyl phenyl acid phosphate and naphthyl acid phosphate are exemplified. The phosphate ester (aryl acid phosphate) may be a monoester, a diester or a mixture thereof.

Nitrogen-Containing Organic Basic Compound The nitrogen-containing organic basic compound is not particularly limited, and includes various compounds. For example, aliphatic tertiary amine compounds such as trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine and dimethylbenzylamine, aromatic tertiary amine compounds such as triphenylamine, N, N −
Dimethyl-4-aminopyridine, 4-diethylaminopyridine, 4-pyrrolidinopyridine, 4-aminopyridine, 2-aminopyridine, 2-hydroxypyridine, 4
-Hydroxypyridine, 2-methoxypyridine, 4-methoxypyridine, imidazole, 2-methylimidazole, 4-methylimidazole, 2-dimethylaminoimidazole, 2-methoxyimidazole, 2-mercaptoimidazole, aminoquinoline, diazabicyclooctane ( DABCO) and the like.

[0043] Further, the general formula _{^{(IX) (NR 9 4)}} + (X 1) - ··· (IX)
And a quaternary ammonium salt represented by In the general formula (IX), R ⁹ is an organic group such as an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a cyclohexyl group, a cycloalkyl group, a phenyl group, And aryl groups such as a tolyl group, naphthyl group and biphenyl group, and arylalkyl groups such as a benzyl group. The four R ^{9 's} may be the same or different, and two R ^{9' s} may combine to form a ring structure. X ¹ represents a halogen atom, a hydroxyl group or BR ₄ .
Here, R represents a hydrogen atom or a hydrocarbon group such as an alkyl group or an aryl group, and the four Rs may be the same or different.

Such quaternary ammonium salts include:
For example, ammonium hydroxides having an alkyl group, an aryl group, an araryl group and the like, such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, trimethylbenzylammonium hydroxide, tetramethylammonium borohydride, tetrabutylammonium Examples include basic salts such as borohydride, tetrabutylammonium tetraphenylborate, and tetramethylammonium tetraphenylborate.

Among these nitrogen-containing organic basic compounds,
Quaternary ammonium salts represented by the above general formula (I), such as tetramethylammonium hydroxide and tetrabutylammonium, have high catalytic activity, are easily thermally decomposed, and do not easily remain in the polymer. Hydroxide, tetramethylammonium borohydride and tetrabutylammonium borohydride are preferred, and tetramethylammonium hydroxide is particularly preferred.

Such a nitrogen-containing organic basic compound may be used alone or in a combination of two or more.
It is preferable that these nitrogen-containing organic basic compounds have a content of metal impurities as small as possible. Particularly, the content of alkali metal and alkaline earth metal compounds is 50 p.
pm or less are preferred.

Polymerization in Solid State The above-mentioned, preferably crystallized, solid prepolymer is further subjected to a polymerization reaction. In this case, the reaction is promoted by extracting the aromatic monohydroxy compound, diaryl carbonate, or both, which are by-produced by the reaction, out of the system. For that, nitrogen,
Introducing an inert gas such as argon, helium, carbon dioxide or a lower hydrocarbon gas, etc. to remove the gas along with these gases, a method of performing the reaction under reduced pressure, or a method of using these in combination It is preferably used.

The shape of the crystallized prepolymer in the case of carrying out the solid phase polymerization reaction is not particularly limited, but is preferably a shape such as a pellet or a bead. As a reaction catalyst in the solid-phase polymerization, a trivalent or pentavalent phosphorus compound or a nitrogen-containing organic basic compound and other catalysts are used as needed, but they are added in the prepolymer production step and remain. The catalyst may be used as it is, or the catalyst may be added again in a powder, liquid or gas state.

The polymerization temperature Tp (° C.) and the polymerization time vary depending on various conditions, but are preferably not lower than the glass transition temperature of the target aromatic polycarbonate and the crystallized prepolymer is not melted during the solid phase polymerization. The heating is performed by heating at a temperature in a range where the solid state is maintained for 1 minute to 100 hours. Generally, the weight average molecular weight of an industrially useful aromatic polycarbonate is about 6,000 to 200,000, but by carrying out the above solid phase polymerization step, a polycarbonate having such a degree of polymerization can be easily obtained.

The obtained crystalline aromatic polycarbonate powder can be directly introduced into an extruder to be pelletized without cooling, or can be directly introduced into a molding machine for molding. Polymerization in Swelled Solid State This is a method in which the prepolymer obtained in the preliminary polymerization step is preferably crystallized, and then further polymerized by solid state polymerization in a state swollen by a swelling gas described later.
The method is divided into a flake forming step of the prepolymer obtained as described above, and a high molecular weight step (swelling solid state polymerization step) by a solid state polymerization method under a swelling solvent flow.

In the flake forming step, conventionally known methods such as a rolling granulation method, an extrusion granulation method, a compression granulation method, a melt granulation method, a spray drying granulation method, a fluidized bed granulation method, A crushing granulation method, a stirring granulation method, a liquid phase granulation method, a vacuum freeze granulation method, or the like can be used depending on the case. The shape of the flake is not particularly limited, but is preferably a pellet, a bead, or the like from the viewpoint of operability.

Next, in the swelling solid phase polymerization step, the prepolymer flakes are further increased in molecular weight while being maintained in a solid state. This step is characterized in that solid phase polymerization is performed in a swelling solvent atmosphere, and the removal efficiency of phenol as a by-product is improved by a swelling effect. Through this step, it is possible to lower the temperature as compared with a normal melt transesterification reaction, and it is possible to significantly reduce the reaction time as compared with a normal solid-phase polymerization or melt transesterification.

The swelling solvent used here is a single swelling solvent capable of swelling polycarbonate under the following reaction conditions:
A mixture of these single swelling solvents, or a mixture of a single swelling solvent or a mixture thereof with a poor solvent of polycarbonate as a single or several kinds of mixtures is shown. The swelling state in this step refers to a state in which the prepolymer flakes, which are the reaction raw materials, are increased volumetrically or by weight above the thermal swelling value within the range of the reaction conditions shown below,
The swelling solvent is a single compound having a boiling point of completely vaporizing under the following reaction conditions, or a single compound having a vapor pressure of usually 50 mmHg or more, or a mixture thereof,
Simultaneously, it refers to one that can form the above-mentioned swollen state.

Such a swelling solvent is not particularly limited as long as it satisfies the above swelling conditions. For example, an aromatic compound or an oxygen-containing compound whose solubility parameter is usually in the range of 4 to 20 (cal / cm ³ ) ^1/2 is applicable. Specific swelling solvents include, for example, aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, diethylbenzene, propylbenzene and dipropylbenzene; ethers such as tetrahydrofuran and dioxane; ketones such as methylethylketone and methylisobutylketone. Is mentioned. Among these, a single compound of an aromatic hydrocarbon having 6 to 20 carbon atoms or a mixture thereof is preferable.

The conditions of the poor solvent mixed with the swelling solvent are as follows. Under the following reaction conditions, the solubility of the polycarbonate in the solvent is 0.1% by weight or less, and the linear or branched polycarbonate is less likely to be involved in the reaction. A saturated hydrocarbon compound having 4 to 18 carbon atoms having a chain, or an unsaturated hydrocarbon compound having 4 to 18 carbon atoms and a low degree is preferred. If the boiling point of both the swelling solvent and the poor solvent exceeds 250 ° C., it becomes difficult to remove the residual solvent, and the quality may deteriorate, which is not preferable.

When a mixture of such a poor solvent and a swelling solvent is used, 1% by weight of the swelling solvent is contained in the mixed solvent.
The swelling solvent is preferably contained in the mixed solvent in an amount of at least 5% by weight. In this swelling solid-state polymerization step, the reaction temperature is preferably 100 to 240 ° C, and the pressure during the reaction is preferably 10 Torr to 5 kg /
It is carried out at cm ² G, particularly preferably at atmospheric pressure.

As a reaction catalyst in this swelling solid phase polymerization step, a trivalent or pentavalent phosphorus compound or a nitrogen-containing organic basic compound and, if necessary, other catalysts are used. The remaining catalyst may be used as it is, or the catalyst may be added again in a powder, liquid or gas state. The supply of the swelling solvent gas is
It may be supplied to the reactor in a liquid state and vaporized in the reactor, or may be vaporized in advance by a heat exchanger or the like and then supplied to the reactor. The flow rate of the swelling solvent gas is 1 × 10 ⁻³ cm /
s or more is sufficient. Further, the gas supply amount is preferably 0.5 liter (standard state) / hr or more per 1 g of the prepolymer. There is no particular limitation on the reactor used for swelling solid phase polymerization.

The drying and pelletizing steps of the high-molecular-weight polycarbonate can be performed by a conventional method, and are not particularly limited. The mixing ratio between the inert gas and the swelling solvent may be such that the mixed solvent gas contains at least 1% by volume of the swelling solvent. In the solid-state polymerization or swollen solid-state polymerization of the present invention, if necessary, pt-butylphenol, p-
-Terminating agents such as cumylphenol and p-phenylphenol can be used. Further, a known branching agent can be used if necessary. Further, if necessary, a known antioxidant may be added to the reaction system. As this antioxidant, a phosphorus-based antioxidant is preferably used.

Oxygen Concentration and Moisture Concentration in Gas Phase in Polymerization System In the present invention, the oxygen concentration in the gas phase in the reaction system in which the polymerization is carried out is preferably 2 ppm or less. Further, the water concentration in the reaction system is also preferably 2 ppm or less. 2 ppm oxygen concentration in the reaction system
Hereinafter, the method for reducing the water concentration to 2 ppm or less is not particularly limited. For example, an oxygen removal tube incorporating an oxygen filter or the like, or a moisture removal tube incorporating a moisture filter or the like is provided in front of the polymerization reactor inlet. Just do it.

The polycarbonate obtained by the present invention can be used by blending known additives such as a plasticizer, a pigment, a lubricant, a release agent, a stabilizer, and an inorganic filler. This polycarbonate is made of polyolefin, polystyrene, polyester, polysulfonate,
It can be blended with polymers such as polyamide and polyphenylene ether. In particular, OH groups, COOH
It is effective when used in combination with a polyphenylene ether, polyether nitrile, terminal-modified polysiloxane compound, modified polypropylene, modified polystyrene, or the like having a terminal such as a group or an NH ₂ group at the terminal.

[0061]

Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. Examples 1 to 6 and Comparative Examples 1 and 2 In a nickel steel autoclave with an internal volume of 1 liter and equipped with a stirrer, 228 g (1.0 mol) of bisphenol A (BPA), 225 g (1.05 mol) of diphenyl carbonate and tetramethylammonium Hydroxide (0.5
Mmol), and the atmosphere was replaced with argon five times. Thereafter, the mixture is heated to 180 ° C. and heated under argon atmosphere for 3 hours.
The reaction was performed for 0 minutes. The temperature is then increased to 240 over 120 minutes.
At the same time, raise the degree of vacuum to 8 mmHg and react, further raise the temperature to 270 ° C over 30 minutes, and at the same time raise the degree of vacuum to 7 mmHg and react, and finally raise the degree of vacuum to 1 mmHg The reaction was performed for 5 minutes. After the reaction was completed, the inside of the reactor was returned to atmospheric pressure with argon, and the content of the prepolymer was taken out and pulverized.

The prepolymer had a viscosity average molecular weight of 8
700, and the terminal fraction of hydroxyl groups was 50%. The prepolymer thus obtained was dissolved in methylene chloride, and the catalyst shown in Table 1 was added. Then, paraxylene was added to precipitate a powder. A polymer powder was obtained. This powder has a diameter of 1
6g, 200g length SUS tube 4g charge, 22
At 0 ° C., nitrogen was flowed at a rate of 50 ml / Hr, and solid phase polymerization was carried out for 90 minutes. After completion of the reaction, the obtained polycarbonate was allowed to stand at 340 ° C. for 90 minutes under a nitrogen stream, and the yellow index (YI) was measured (retention burn test). The results are shown in Table 1.

Examples 7 to 9 and Comparative Examples 3 to 4 The same procedures as in Example 1 were carried out except that paraxylene was flowed at a rate of 20 g / Hr instead of flowing nitrogen at a rate of 50 ml / min. The results are shown in Table 1. Example 10 In a vessel equipped with a stirrer having an inner volume of 50 liters, 9.2 mol of bisphenol A as dihydric phenol, 9.4 liters of a 2.0 N aqueous sodium hydroxide solution and 8 liters of methylene chloride were stirred, and phosgene was sufficiently added thereto. 3 as excess
Blow for 0 minutes.

Then, 0.18 mol of phenol was reacted, 0.4 mol of bisphenol A, 0.022 mol of triethylamine and 4.5 liter of 0.2N aqueous sodium hydroxide were added, and the mixture was reacted for 40 minutes. The phases were separated from the organic phase. Thus, a methylene chloride solution of the PC oligomer was obtained. Eight liters of this methylene chloride solution of the PC oligomer, 2.5 mol of bisphenol A, 0.18 mol of methyl chloroformate, 400 g of a 7.25% by weight aqueous sodium hydroxide solution, 0.017 mol of triethylamine and 8 liter of methylene chloride were mixed. The mixture was stirred at 500 rpm and reacted for 60 minutes.

After the reaction, the aqueous phase and the organic phase are separated, and the organic phase is separated from water, alkali (0.01N aqueous sodium hydroxide solution),
An organic solvent solution of PC prepolymer was sequentially washed with an acid (0.1N hydrochloric acid) and pure water. The methylene chloride was removed from a part of this to obtain a prepolymer powder, and the viscosity average molecular weight was measured to be 8,700. The prepolymer thus obtained was pulverized while removing and evaporating methylene chloride from the organic solvent solution of the prepolymer to obtain a prepolymer powder.

A polycarbonate was obtained in the same manner as in Example 1 except that the thus obtained prepolymer was used. The results are shown in Table 1. Comparative Example 5 The same operation was performed as in Comparative Example 1, except that the prepolymer obtained in Example 10 was used. The results are shown in Table 1. Example 11 A polycarbonate was obtained in the same manner as in Example 4, except that the prepolymer obtained in Example 10 was used. The results are shown in Table 1.

In the table, the viscosity average molecular weight Mv is determined by calculating the intrinsic viscosity [η] in methylene chloride at 20 ° C.
It was calculated from 1.23 × 10 ⁻⁵ × Mv ^0.83 . In the high-temperature and high-humidity test, after drying at 120 ° C. for 5 hours or more,
Form a 2cm, 1.2mm thick disk, 80 ℃, 85% R
Exposure was performed for 48 hours under the condition of H. Thereafter, the number of white spots having a diameter of 10 μm or more was read by a transmission deflection microscope.

In the retention burn test, the polycarbonate as a sample was left at 340 ° C. for 90 minutes under a nitrogen gas flow.
A 2.4% methylene chloride solution of the sample was measured for YI (yellow index) using a color meter SM-3 (manufactured by Suga Test Instruments Co., Ltd.) using a quartz cell having an optical path length of 57 mm.

[0069]

[Table 1]

[0070]

According to the present invention, a high-quality polycarbonate which is excellent in thermal stability, does not deteriorate in quality even in a high-temperature and high-humidity environment, has a good color tone, and is extremely useful as an optical material is produced. be able to.

Claims (3)

[Claims] 1. A method for producing a polycarbonate, comprising preparing a polycarbonate prepolymer by preliminary polymerization, and polymerizing the prepolymer in a solid state or a swollen solid state using a trivalent or pentavalent phosphorus compound as a catalyst. 2. A method for producing a polycarbonate, comprising preparing a polycarbonate prepolymer by preliminary polymerization, and polymerizing the prepolymer in a solid state or a swollen solid state using a nitrogen-containing organic basic compound as a catalyst. 3. A polycarbonate for an optical material obtained by the production method according to claim 1.