JPH06102720B2 - Method for producing aromatic polycarbonate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel method for producing an aromatic polycarbonate. More specifically, the present invention polymerizes a dihydroxydiaryl compound and a diarylcarbonate in the presence of a specific terminal blocking agent to give an aromatic polycarbonate having excellent physical properties and having a high molecular weight nucleus-substituted phenylcarbonate group terminal. The present invention relates to a method suitable for industrial implementation for efficient production.

2. Description of the Related Art In recent years, aromatic polycarbonate has been improved in heat resistance, impact resistance,
It is widely used in many fields as an engineering plastic with excellent transparency. Various studies have been conducted on the production method of this aromatic polycarbonate, and among them, aromatic dihydroxy compounds such as 2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as bisphenol A) and phosgene Has been industrialized.

However, in this interfacial polycondensation method using phosgene, toxic phosgene must be used,
There are problems that the equipment will be corroded by chlorine-containing compounds such as hydrogen chloride and sodium chloride that are by-produced, and that it will be difficult to separate impurities such as sodium chloride mixed in the resin that adversely affect the physical properties of the polymer. Since methylene chloride which is usually used as a reaction solvent is a good solvent for polycarbonate and has an extremely high affinity,
In the generated polycarbonate, the methylene chloride is unavoidably left behind, and as a result, due to heating during molding,
The residual methylene chloride is decomposed to generate hydrogen chloride, which may lead to corrosion of the molding machine and deterioration of polymer quality. It is very costly to industrially reduce the amount of residual methylene chloride, and it is almost impossible to completely remove the residual methylene chloride.

As described above, the phosgene method involves many problems when it is industrially implemented.

On the other hand, a method for producing an aromatic polycarbonate from an aromatic dihydroxy compound and a diaryl carbonate has also been known for a long time, and for example, phenol is eliminated by a transesterification reaction between bisphenol A and diphenyl carbonate in a molten state to give a polycarbonate. The manufacturing method has been industrialized as a so-called transesterification method or another name melting method. However, in this method, the degree of polymerization does not increase unless the phenol and finally diphenyl carbonate are distilled out from the melt of the high-viscosity polycarbonate. And, it is necessary to react for a long time under high vacuum of 1 mmHg or less.
(1) It requires special equipment suitable for high temperature and high vacuum and strong stirring equipment due to high viscosity of the product. (2) It is commonly used in the plastics industry due to high viscosity of the product. With the reactor and stirring type, only polymers with a weight average molecular weight of about 30,000 can be obtained, (3)
Since the reaction is carried out at a high temperature, branching and cross-linking are likely to occur due to side reactions, making it difficult to obtain a good quality polymer (4)
It has various drawbacks, such as unavoidable coloring due to long-term residence at high temperature [Mikio Matsugane et al., Plastic Material Course [5] "Polycarbonate Resin", published by Nikkan Kogyo Shimbun (Showa 44), No. 62- See page 67].

Furthermore, the polycarbonate obtained by this melting method has a wide molecular weight distribution and is known to have a large number of branched structures. Therefore, as compared with the polycarbonate produced by the phosgene method, a drawback in strength, for example, Defects such as high brittle fracture property and non-Newtonian flow behavior have been pointed out [see "Polymer", Vol. 27, p. 521 (1978)]. It is also known that the polycarbonate known by the melting method is inferior in basic physical properties as an engineering plastic such as heat resistance and hot water resistance.

By the way, polyhexamethylene adipamide (nylon 66) and polyethylene terephthalate (PET), which are the most common condensation type polymers, are usually polymerized by melt polymerization up to a molecular weight that has sufficient mechanical properties for plastics and fibers. However, the high-molecular weight polymer produced in this manner, under reduced pressure or under the flow of dry nitrogen or the like, by heating to a temperature at which the solid state can be maintained, solid phase polymerization is performed. It is already known that it is possible to further increase the degree of polymerization. In this solid phase polymerization, it is considered that in the solid polymer, the terminal carboxyl group reacts with the terminal amino group or terminal hydroxyl group existing in the vicinity to cause dehydration condensation. Further, in the case of polyethylene terephthalate, a condensation reaction with de-ethylene glycol also occurs partially.

In this way, nylon 66 and polyethylene terephthalate can be highly polymerized by solid phase polymerization because these polymers are originally crystalline polymers having high melting points (265 ° C and 260 ° C, respectively), This is because the solid state can be sufficiently maintained at the temperature at which solid phase polymerization proceeds (for example, 230 to 250 ° C.). More importantly, the compound to be desorbed is a substance having a small molecular weight and a relatively low boiling point, such as water or ethylene glycol, which easily migrates in a solid polymer and becomes a gas outside the system. It can be removed.

On the other hand, a method has also been proposed in which a high melting point aromatic polyester carbonate having both an aromatic ester bond and a carbonate bond is melt-polymerized and then solid-phase polymerized. This method is obtained by reacting an aromatic dicarboxylic acid such as naphthalenedicarboxylic acid, p-hydroxybenzoic acid or terephthalic acid or an aromatic hydroxycarboxylic acid with a dihydroxy aromatic compound and a diaryl carbonate in a molten state. After the polymer is crystallized, solid phase polymerization is carried out (however, when p-hydroxybenzoic acid is used, if the degree of polymerization in melt polymerization increases to a certain degree, it cannot be maintained in a molten state and becomes a solid state). Since this is a highly crystalline prepolymer having a high melting point, it is not necessary to further crystallize it) (JP-A-48-22593, JP-A-49-31796,
U.S. Pat. No. 4,107,143, JP-A-55-98224). However, these methods generate 30 ester bonds.
% Or more, usually about 50% or more, which is a method that can be applied when producing an aromatic polyester carbonate. When the ester bond is less than 30%, melting of the prepolymer occurs during solid-phase polymerization and solidification occurs. It is also known that phase polymerization was impossible (JP-A-55-98224).

On the other hand, it is also known that such an ester bond has an effect of accelerating a reaction of forming a carbonate bond when producing an aromatic polyester carbonate (Japanese Patent Publication No. 52-36797). According to this Japanese Patent Publication No. 52-36797, when a high molecular weight aromatic polycarbonate containing an ester bond is produced by the melt polycondensation method, an ester bond is previously formed in the molecular chain of the aromatic polycarbonate having a low degree of polymerization. It has been clarified that the melt polycondensation reaction is significantly promoted by the introduction. As a matter of course, even in solid phase polymerization, it is presumed that such a polycondensation reaction promoting effect of the ester bond is also exerted. Therefore, it is necessary to increase the degree of polymerization of an originally crystalline aromatic polyester carbonate having a high melting point or an aromatic polyester carbonate which can easily become a crystalline polymer having a high melting point by a slight crystallization operation by solid phase polymerization. Is
It's relatively easy.

However, in an attempt to produce a high-molecular-weight aromatic polycarbonate containing no ester bond by melt-polymerization and then solid-phase polymerization, a highly crystalline special polycarbonate having a high melting point of 280 ° C. or higher is solidified. Example to be obtained by phase polymerization (JP-A-52-109591)
Little was known, except for Example 3). The method disclosed in JP-A-52-109591 is a melt polymerization of an aromatic dihydroxy compound consisting of about 70 mol% of hydroquinone and about 30 mol% of bisphenol A and diphenyl carbonate.
Prepolymer having a melting point of 280 ° C or higher, which was solidified at a temperature of 280 ° C under a high vacuum of 0.5 mmHg, was heated to 280 ° C and the vacuum
Solid phase polymerization is carried out under the conditions of 0.5 mmHg and a reaction time of 4 hours.

However, no attempt has been made to produce aromatic polycarbonates, which are substantially amorphous polymers based on dihydroxydiarylalkanes such as boss phenol A, by solid state polymerization of relatively low molecular weight prepolymers. Didn't. For example, in the phosgene method using an acid binder, which is the most common method for producing an aromatic polycarbonate, what is to be eliminated is usually a solid without a solvent such as sodium chloride, which is a solid polymer. It is extremely difficult to move through it to get out of the system, and thus it is essentially impossible to carry out this method in the solid phase.

In addition, polycarbonate of bisphenol A, which is the most common aromatic polycarbonate, is
Also in the method of producing by transesterification reaction with and diphenyl carbonate, all high temperature, melt polymerization method under high vacuum has been studied, for high polymerization by solid state polymerization of the prepolymer as in the present invention, It wasn't considered at all. This is because the polycarbonate of bisphenol A is an amorphous polymer having a glass transition temperature (Tg) of 149 to 150 ° C., and thus it was considered impossible to perform solid phase polymerization. That is, in general, in order to enable solid phase polymerization, it is necessary that the polymer can maintain a solid state at a temperature equal to or higher than the glass transition temperature without causing fusion and the like. This is because in the case of the polycarbonate, fusion bonding and the like occurred at a temperature of 150 ° C. or higher, and solid phase polymerization was substantially impossible as it was.

On the other hand, it is known that the polycarbonate having various hydrocarbon group-substituted phenyl carbonate group terminals has excellent fluidity, heat resistance, and hot water resistance. However, in the transesterification method, since diphenyl carbonate is usually used, the terminal becomes a phenyl carbonate group. On the other hand, if a hydrocarbon group-substituted diphenyl carbonate is used, it is possible to make the terminal a hydrocarbon group-substituted phenyl carbonate group.
Since the hydrocarbon group-substituted phenol, which is a by-product of the condensation, has a high boiling point, it is difficult to distill it out of the system, which causes a problem that the polymerization time becomes long and it is difficult to obtain a desired degree of polymerization. Furthermore, the hydrocarbon group-substituted diphenyl carbonate itself is not easy to manufacture or purify,
It also has the drawback of being difficult to use industrially.

In addition, solid phase polymerization generally requires that the polymerization be carried out while maintaining a solid state, so that there is an upper limit to the polymerization temperature, and the polymerization temperature is lower and the solid phase polymerization time is longer than in the melt polymerization method. Therefore, shortening the solid phase polymerization time is a major issue.

The present invention overcomes various drawbacks of the conventional methods for producing various polycarbonates, is substantially free from impurities such as chlorine compounds, and has a desired terminal group. The purpose of the present invention is to provide a method for efficiently producing a high-molecular weight polycarbonate by a solid phase polymerization method in a relatively short solid phase polymerization time.

Means for Solving the Problems The inventors of the present invention have conducted extensive studies on a method for producing an aromatic polycarbonate using a transesterification reaction, and as a result, have shown that the compound represented by the general formula: HO-Ar ¹ -Y-Ar ² -OH (I) (Wherein Ar ¹ and Ar ² are each an arylene group, Y is an alkylene group or a substituted alkylene group) and a dihydroxydiaryl compound mainly containing a dihydroxydiarylalkane and a diaryl carbonate,
It was found that the above object can be achieved by prepolymerizing in the presence of a specific end-capping agent, then crystallizing this, and further solid-phase polymerizing, and based on this finding, the present invention was completed. It was

That is, the present invention has the general formula HO-Ar ¹ -Y-Ar ² -OH (I) (wherein Ar ¹ and Ar ² are arylene groups, and Y is an alkylene group or a substituted alkylene group). In producing an aromatic polycarbonate by reacting a dihydroxydiaryl compound mainly composed of the represented dihydroxydiarylalkane with a diarylcarbonate, (a) at least one terminal selected from a nucleus-substituted phenol compound and a naphthol compound In the presence of an occluding agent, the dihydroxydiaryl compound and the diaryl carbonate are heated and reacted to give a number average molecular weight of 1,000 to 1
Prepolymerization step to form 0,000 prepolymer, (b) crystallization step to crystallize the prepolymer obtained in step (a) to form a crystallized prepolymer, and (c) obtained in step (b) The crystallized prepolymer, which is higher than the glass transition temperature of the aromatic polycarbonate produced,
In addition, the crystallized prepolymer is heated to a temperature within a range where a solid phase can be maintained, and a solid phase polymerization step for further increasing the degree of polymerization is sequentially performed. A manufacturing method is provided.

Particularly preferred embodiments of the production method of the present invention include: (1) prepolymerization without catalyst, (2) solid phase polymerization without catalyst, (3) both prepolymerization and solid phase polymerization And (4) performing prepolymerization in a molten state, (5) having a crystallinity of the crystallized prepolymer in the range of 5 to 55%, and (6) crystallizing the prepolymer. And (7) the prepolymer is crystallized by heating the prepolymer, and (8) the dihydroxydiarylalkane is 2,2-bis (4-hydroxy). Phenyl) propane, (9) diaryl carbonate is diphenyl carbonate, and the like.

In addition, the aromatic polycarbonate according to the present invention is obtained by using a dihydroxydiaryl compound and a diaryl carbonate that do not contain a chlorine atom as raw materials, and crystallizing the prepolymer using a non-chlorine-based solvent. It is desirable that it does not contain chlorine atoms.

The present invention enables solid-phase polymerization of the prepolymer, even if it is a substantially amorphous prepolymer, by performing the crystallization step.

In the conventional transesterification method by the melting method, in order to desorb phenol and diphenyl carbonate from the high-viscosity melt, the final temperature is 0.1 mm at a high temperature of 300 ° C or higher.
While it is necessary to create a high vacuum below Hg, while desorbing relatively high-boiling aromatic monohydroxy compounds and diaryl carbonates from the crystallization prepolymer in the solid state at a temperature much lower than 300 ° C. However, it was totally unexpected that the prepolymer easily increased in molecular weight.

In the method of the present invention, the dihydroxydiaryl compound used as a raw material has a general formula: HO-Ar ¹ -Y-Ar ² -OH (I) (wherein Ar ¹ , Ar ² and Y have the same meanings as described above) Is a dihydroxydiarylalkane. Ar ¹
And Ar ² each represent an arylene group, for example, a group such as phenylene, naphthylene, biphenylene, and pyridylene, and Ar ¹ and Ar ² may be the same or different from each other. Y is Represents an alkylene or substituted alkylene group (wherein
R ¹ , R ² , R ³ and R ⁴ are each a hydrogen atom, a lower alkyl group, a cycloalkyl group, an aryl group or an aralkyl group, which may be optionally substituted with a halogen atom or an alkoxy group, k Represents an integer of 3 to 11, and the above formula Hydrogen atom may be substituted with a lower alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkoxy group, a halogen atom or the like).

In addition to the dihydroxydiarylalkane represented by the above general formula (I), the starting dihydroxydiaryl compound is a dihydroxydiaryl compound other than the dihydroxydiarylalkane, for example, the general formula HO -Ar ¹ -Z-Ar ² -OH (III) [wherein Ar ¹ and Ar ² have the same meanings as described above, Z is a bond, or -O-, -CO-, -S-,- SO ₂ −, −CO ₂
A divalent diaryl compound represented by the formula:-, -CON (R ¹ ) (R ¹ has the same meaning as described above) and the like].

Furthermore, in such an arylene group (Ar ¹ , Ar ² ), one or more hydrogen atoms may have other substituents that do not adversely affect the reaction, for example, a halogen atom, a lower alkyl group,
It may be substituted with a lower alkoxy group, a phenyl group, a phenoxy group, a vinyl group, a cyano group, an ester group, an amide group or a nitro group.

Examples of the dihydroxydiarylalkane represented by the general formula (I) include, for example, (R ⁵ and R ⁶ in the formula are each a hydrogen atom, a halogen atom, a lower alkyl group having 1 to 4 carbon atoms, a lower alkoxy group having 1 to 4 carbon atoms, a cycloalkyl group, or a phenyl group. ^May be the same or different from each other, m and n are integers of 1 to 4, and when m is 2 or more, R ⁵ may be different from each other; When R is 2 or more, R ⁶ may be different from each other) and bisphenols and the like are preferably used.

Among these compounds, bisphenol A which is 2,2-bis (4-hydroxyphenyl) propane and substituted bisphenol A's are particularly preferable. Further, these dihydroxydiaryl alkanes may be used alone,
You may use it in combination of 2 or more type. When two or more kinds of dihydroxydiarylalkanes are used, an aromatic polycarbonate which is a copolymer having two or more kinds of these skeletons is usually obtained.

The dihydroxydiaryl compound represented by the general formula (III) is, for example, Dihydroxybiphenyls represented by: (Wherein R ⁵ , R ⁶ , m and n have the same meanings as described above) and the like.

Further, the dihydroxydiaryl compound used as a raw material in the method of the present invention is a dihydric diaryl compound containing 60 mol% or more of the above-mentioned dihydroxydiarylalkane and a trivalent or more polyhydric phenol containing three or more phenolic hydroxyl groups in the molecule. Against
It can also be used in a proportion of about 0.01 to 3 mol%.

Examples of such trihydric or higher polyhydric phenols include phloroglucin; phlorogluside; 4,6-dimethyl-2,4,
6-tri (4'-hydroxyphenyl) heptene-2; 2,
6-Dimethyl-2,4,6-tri (4'-hydroxyphenyl) heptene-3; 4,6-dimethyl-2,4,6-tri (4'-
Hydroxyphenyl) heptane; 1,3,5-tri (4'-hydroxyphenyl) benzene; 1,1,1-tri (4'-hydroxyphenyl) ethane; 2,2-bis [4,4-bis (4 ′
-Hydroxyphenyl) cyclohexyl] propane; 2,6
-Bis (2'-hydroxy-5'-methylbenzyl)-
4-methylphenol; 2,6-bis (2'-hydroxy-
5'-isopropylbenzyl) -4-isopropylphenol; bis- [2-hydroxy-3- (2'-hydroxy-5'-methylbenzyl) -5-methylphenyl]
Methane; tetra (4-hydroxyphenyl) methane; tri (4-hydroxyphenyl) phenylmethane; bis (2,4-hydroxyphenyl) ketone; 1,4-bis (4 ',
4 ″ -dihydroxytriphenylmethyl) benzene; 1,
4-dimethyl-1,4-bis (4'-hydroxy-3-methylphenyl) -6-hydroxy-7-methyl-1,2,3,
4-tetralin; 2,4,6-tri (4'-hydroxyphenylamino) -S-triazine and the like.

On the other hand, the diaryl carbonate which is another raw material of the present invention is represented by the general formula Is an aromatic carbonic acid ester represented by
³ and Ar ⁴ are aryl groups, which may be the same or different from each other.

Further, in Ar ³ and Ar ⁴ , one or more hydrogen atoms are
Other substituents that do not adversely affect the reaction, for example, halogen atom, lower alkyl group, lower alkoxy group, phenyl group, phenoxy group, vinyl group, cyano group, ester group,
It may be substituted with an amide group, a nitro group, or the like.

Examples of such diaryl carbonate include (R ⁷ and R ⁸ in the formula are each a hydrogen atom, a halogen atom, a lower alkyl group having 1 to 4 carbon atoms, a lower alkoxy group having 1 to 4 carbon atoms, a cycloalkyl group or a phenyl group, p
And q are integers of 1 to 5, and when p is 2 or more, R ⁷ may be different from each other, and when q is 2 or more, R ⁸ may be different from each other. ) And substituted or unsubstituted diphenyl carbonates. Among these diphenyl carbonates, symmetrical diaryl carbonates such as diphenyl carbonate and lower alkyl-substituted diphenyl carbonates such as ditolyl carbonate and di-t-butylphenyl carbonate are preferable, but the diaryl carbonate having the most simple structure is particularly preferable. Diphenyl carbonate is preferred.

These diaryl carbonates may be used alone or in combination of two or more, but since the reaction system becomes complicated and there is not much advantage, it is preferable to use one symmetrical diaryl carbonate. Good.

The step (a) of the method of the present invention is carried out in the presence of a terminal blocking agent. (In the formula, R is a halogen atom, an alkyl group, a halogenated alkyl group, an alkoxy group, a halogenated alkoxy group or an aralkyl group, 1 is an integer of 1 to 5, and 1 is 2 to 5
In which R may be different from each other) and a nucleus-substituted phenol compound represented by The naphthol compound represented by is used.

R in the general formula (II) is a halogen atom or an alkyl group, a halogenated alkyl group, an alkoxy group, a halogenated alkoxy group, or an aralkyl group, and these groups are linear or branched. Either may be used. Also l
Is an integer of 1 to 5, and when 1 is 2 to 5, Rs may be the same or different. Specific examples of the phenol derivative represented by the general formula (II) include p-methylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, p-ethylphenol, p-propylphenol, p-isopropylphenol. , P-n-butylphenol, p-tertiary butylphenol, p-tertiary butylphenol, p-nonylphenol, p-pentylphenol, p-isopentylphenol, p-hexylphenol, p-heptylphenol, p-chlorophenol, p. -Bromophenol, 2,4-dichlorophenol, 2,4,6-tribromophenol, pt-octylphenol, p-dodecylphenol, 2- (3,5-dimethylheptyl) phenol, 4- (3,5 -Dimethylheptyl) phenol, 4
-(1,1,3,3-tetramethylbutyl) phenol, octyloxyphenol, nonyloxyphenol, palmityloxyphenol, octadecyloxyphenol, dodecyloxyphenol, cumylphenol and the like can be mentioned. Further, examples of the naphthol compound include α-naphthol and β-naphthol.

These end-capping agents may be used alone or in combination of two or more, but the substituted phenol having a branched alkyl chain has a large effect of accelerating the solid-state polymerization rate. It is advantageous. The amount of the terminal blocking agent used varies depending on the type and molecular weight of the desired polycarbonate, but is usually selected in the range of 1 to 100 mmol per mol of the dihydroxydiaryl compound. If this amount is less than 1 millimole, the effect of accelerating the solid phase polymerization rate is small, but it was unexpected that addition of such a small amount as a few millimoles accelerates the solid phase polymerization rate. on the other hand,
Increasing the amount of the end-blocking agent increases the proportion of the substituted phenyl carbonate end groups, and thus the proportion of the substituted phenyl carbonate end groups in the end groups of the final polymer after solid phase polymerization. By increasing this end group,
The fluidity, heat resistance, and hot water resistance of the final polymer can be improved. This terminal blocking agent may be added from the beginning of the solid phase polymerization or may be added during the preliminary polymerization. If the prepolymer is added during the prepolymerization, the molecular weight of the prepolymer decreases once, so it is necessary to carry out the polymerization again and raise the polymerization degree to a predetermined degree. When diphenyl carbonate is used as the diaryl carbonate, the terminal blocking agent has a higher boiling point than the by-produced phenol, so even when the by-produced phenol is withdrawn to the polymerization system, it remains in the polymerization system and is polymerized at the polymer end. A prepolymer is obtained which is incorporated and partially endcapped with a substituted phenol or naphthol. Although these reactions are equilibrium reactions, the equilibrium reaction itself is extremely fast, and reaches equilibrium within 1 to 30 minutes at a high temperature of 150 ° C or higher, and the withdrawal of by-products (for example, phenol) generally becomes the rate-determining factor of polymerization. .

In the step (b) of the method of the present invention, the prepolymer obtained in the prepolymerization step is crystallized and then solid-phase polymerized. In the prepolymerization step, a dihydroxydiaryl compound and a diaryl carbonate (for example, diphenyl carbonate) are used. Carbonate) in the presence of a terminal blocking agent by heating to remove an aromatic monohydroxy compound (for example, phenol) which is a compound in which a hydroxyl group is bonded to an aryl group based on diaryl carbonate, Allow the polymer to form. The number average molecular weight (Mn) of the prepolymer obtained in this prepolymerization step is
It is selected in the range of 1,000 to 10,000. This number average molecular weight (M
When n) is less than 1,000, the reaction time of solid phase polymerization is long, which is not preferable, and it is not necessary to make it larger than 10,000.

The prepolymerization reaction is preferably carried out in a molten state.
The prepolymer having such a molecular weight range does not have such a high melt viscosity, and thus is easy to carry out industrially.

Of course, when carrying out this prepolymerization reaction, a solvent inert to the reaction, for example, methylene chloride, chloroform, 1,
2-dichloroethane, tetrachloroethane, dichlorobenzene, tetrahydrofuran, diphenylmethane, diphenyl ether and the like may be used, but they are usually carried out without a solvent and in a molten state.

Usage ratio of diaryl carbonate and dihydroxydiaryl compound in this prepolymerization reaction (preparation ratio)
Is different depending on the type of the diaryl carbonate and the dihydroxy diaryl compound used, the reaction temperature, the ratio of the diaryl carbonate or the dihydroxy aryl compound distilled out of the system during the polymerization, and the diaryl carbonate is 1 mol of the dihydroxy diaryl compound. On the other hand, it is usually 0.5 to 2.5 mol, preferably 0.50 to
Used in a ratio of 2.0 mol.

The terminal of the prepolymer thus obtained has a formula derived from diphenyl carbonate, for example, when diphenyl carbonate is used as the diaryl carbonate. An aryl carbonate group terminal consisting of a phenyl carbonate group represented by and a nucleus-substituted phenyl carbonate group derived from a terminal blocking agent, for example, the general formula HO-Ar ¹ -... (VII) (Ar ¹ in the formula has the same meaning as described above. And a hydroxyl group terminal based on a dihydroxydiaryl compound represented by The ratio of the aryl carbonate group terminal to all the terminal groups of this prepolymer depends on the molar ratio of the diaryl carbonate and the dihydroxydiaryl compound substantially reacted in the reaction system, and does not depend on the reaction amount of the terminal blocking agent.

Further, depending on the reaction conditions, a part of one of the components or a part of both components may be distilled out during the prepolymerization reaction. It is also a preferable method to add any of the components during the prepolymerization reaction.

In this way, when prepolymerization is carried out so that the aryl carbonate group end is more than 50 mol% in all the end groups,
Not only the coloring of the prepolymer in this step and the coloring of the aromatic polycarbonate in the solid-state polymerization step are significantly suppressed, but the aromatic polycarbonate obtained by the solid-state polymerization has an amount of terminal hydroxyl groups described later. Since it is extremely small, the hot water resistance and heat resistance are good.

Further, the reaction temperature and reaction time when carrying out the prepolymerization step, the type and amount of the raw material dihydroxydiaryl compound, the diaryl carbonate and the substituted phenol, the type and amount of the catalyst used if necessary, the prepolymer obtained Although it depends on the degree of polymerization required, the other reaction conditions, etc., it is usually 50 to 350 ° C., preferably 100 to 320 ° C., usually 1 minute to 100 hours, preferably 2
Selected in the range of minutes to 10 hours.

In order not to color the prepolymer, it is desirable to carry out the prepolymerization reaction at the lowest temperature possible and in a short time.
Therefore, sometimes preferable conditions are that the reaction temperature is 150 to 280 ° C.
And a reaction time of several minutes to several hours. In the method of the present invention, since a prepolymer having a relatively low molecular weight may be produced by this prepolymerization, a colorless and transparent prepolymer having a required degree of polymerization can be easily obtained under the above-mentioned conditions.

In this prepolymerization reaction, an aromatic monohydroxy compound (phenol in the case of diphenyl carbonate), which is a compound in which a hydroxyl group is bonded to an aryl group based on diaryl carbonate, is produced as the reaction progresses. Since the speed can be increased by removing the gas from the reaction system, effective stirring is performed, and at the same time, an inert gas such as nitrogen, argon, helium, or carbon dioxide, or a lower hydrocarbon gas is introduced to generate the gas. A method of removing the incoming aromatic monohydroxy compound (phenol in the case of diphenyl carbonate) by accommodating these gases, a method of performing a reaction under reduced pressure, a method of using these in combination, and the like are used.

When diphenyl carbonate is used as the diaryl carbonate, the substituted phenol has a higher boiling point than the by-produced phenol, so that it is difficult to distill out of the system and reacts to form a polymer terminal.

This prepolymerization reaction can be carried out without adding a catalyst, which is one of the particularly preferred embodiments, but a polymerization catalyst can be used if necessary to accelerate the polymerization rate. Such a polymerization catalyst may be a polycondensation catalyst used in this field and is not particularly limited, but may be an alkali metal such as lithium hydroxide, sodium hydroxide, potassium hydroxide or calcium hydroxide and an alkali. Earth metal hydroxides; alkali metal salts, alkaline earth metal salts, quaternary ammonium salts of hydroxides of boron and aluminum such as lithium aluminum hydroxide, sodium borohydride, and tetramethylammonium boron hydroxide. ; Alkoxides of alkali metals and alkaline earth metals such as lithium methoxide, sodium ethoxide, calcium methoxide; lithium phenoxide, sodium phenoxide, magnesium phenoxide, LiO-Ar-OLi, NaO-Ar-ONa (Ar is an aryl group ) Alkali and alkaline earth metals Oxides; lithium acetate, calcium acetate, alkali metal and organic acid salts of alkaline earth metals such as sodium benzoate; zinc oxide, zinc compounds such as zinc acetate, zinc phenoxide; boron oxide, boric acid, sodium borate,
Trimethyl borate, tributyl borate, triphenyl borate, (R ¹ R ² R ³ R ⁴ ) NB (R ¹ R ² R ³ R ⁴ ) or (R ¹ R ² R ³ R ⁴ ) PB
Compounds of boron such as ammonium borates or phosphonium borates represented by (R ¹ R ² R ³ R ⁴ ) (R ¹ , R ² , R ³ and R ⁴ are as described above); silicon oxide, sodium silicate , Compounds of silicon such as tetraalkyl silicon, tetraaryl silicon, diphenyl-ethyl-ethoxy silicon; germanium oxide, germanium tetrachloride,
Compounds of germanium such as germanium ethoxide and germanium phenoxide; tin compounds combined with an alkoxy group or an aryloxy group such as tin oxide, dialkyltin oxide, diaryltin oxide, dialkyltin carboxylate, tin acetate and ethyltin tryptoxide , Tin compounds such as organotin compounds; lead compounds such as lead oxide, lead acetate, lead carbonate, basic lead carbonate, lead and organic lead alkoxides or aryl oxides; quaternary ammonium salts, quaternary ammonium salts Onium compounds such as phosphonium salts and quaternary arsonium salts; Antimony compounds such as antimony oxide and antimony acetate;
Manganese compounds such as manganese acetate, manganese carbonate and manganese borate; titanium compounds such as titanium oxide, titanium alkoxide or aryl oxide; zirconium acetate, zirconium oxide, zirconium alkoxide or aryl oxide, zirconium such as zirconium acetylacetone. It is possible to use a catalyst such as the compounds of

When a catalyst is used, these catalysts may be used alone or in combination of two or more. Also,
The amount of these catalysts used is usually selected from the range of 0.000001 to 1% by weight, preferably 0.000005 to 0.5% by weight, based on the starting dihydroxydiaryl compound.

Such catalysts usually remain intact in the final aromatic polycarbonate. Since such a residual catalyst may adversely affect the physical properties of the polymer, it is preferable that the amount of the catalyst used is as small as possible.

In the process of the present invention, the prepolymerization step only has to produce a relatively low molecular weight prepolymer, so it is advantageous to carry out it substantially catalyst-free without the addition of such catalysts. What can be done in this way is one of the major features of the method of the present invention.

In a preferred embodiment of the prepolymerization reaction, it is carried out in a molten state without using a solvent. However, the prepolymer thus obtained as it is cooled to around room temperature generally has a low crystallinity. Many are substantially amorphous. However, such a prepolymer in an amorphous state is melted or fused at a temperature near the glass transition temperature of the target aromatic polycarbonate. Is impossible. Therefore, in the step (b) of the method of the present invention, it is necessary to crystallize the prepolymer.

Although the prepolymerization step of the method of the present invention gives a relatively low molecular weight prepolymer, in contrast to various studies on the crystallization behavior of high molecular weight aromatic polycarbonates produced by the phosgene method, So far, few attempts have been made to crystallize such a relatively low molecular weight prepolymer.

The method of crystallizing such a prepolymer is not particularly limited, but in the present invention, a solvent treatment method and a heating crystallization method are preferably used, and when a polymerization catalyst is not used, a solvent treatment method is particularly preferable. This solvent treatment method is a method of crystallizing a prepolymer using an appropriate solvent, specifically, after dissolving the prepolymer in a solvent, a method of precipitating a crystalline prepolymer from this solution, A method of using a solvent having a low dissolving power for the prepolymer, contacting the prepolymer with a liquid solvent or solvent vapor for a time required for the solvent to penetrate into the prepolymer and crystallize the prepolymer, etc. Is preferably used.

As a method of depositing a crystalline prepolymer from the prepolymer solution, there are, for example, a method of removing the solvent from the solution by means such as evaporation of the solvent, a method of adding a poor solvent for the prepolymer, and the like. The method of removing the solvent is simple and preferable. Further, the time required to crystallize the prepolymer by permeating the solvent into the prepolymer, depending on the type and molecular weight of the prepolymer, the shape, or the type of solvent used, the processing temperature, etc.,
It is usually selected in the range of several seconds to several hours. The treatment temperature is usually selected in the range of -10 to 200 ° C.

Preferred solvents that can be used for solvent treatment of such prepolymers include, for example, chloromethane, methylene chloride, chloroform, carbon tetrachloride, chloroethane, dichloroethane (various), trichloroethane (various), trichloroethylene, tetrachloroethane (various). ) And other aliphatic halogenated hydrocarbons; chlorobenzene, dichlorobenzene, and other aromatic halogenated hydrocarbons; tetrahydrofuran, dioxane, and other ethers; methyl acetate, ethyl acetate, and other esters; acetone, methyl ethyl ketone, and other ketones And aromatic hydrocarbons such as benzene, toluene and xylene. These solvents may be used alone or in combination of two or more.

The amount of solvent used for solvent treatment of the prepolymer is
Although it varies depending on the type of prepolymer or solvent, the required crystallinity, the treatment temperature, etc., it is usually selected in the range of 0.05 to 100 times, preferably 0.1 to 50 times, the weight of the prepolymer.

Even if a chlorine-based solvent such as methylene chloride is used for the solvent treatment of the prepolymer, the molecular weight of the prepolymer is relatively low in the present invention, so that the methylene chloride should not be left in the crystallized prepolymer. It's relatively easy. In the phosgene method, it is necessary to distill off methylene chloride from a high molecular weight aromatic polycarbonate, but it is difficult to completely remove this. On the other hand, in the method of the present invention, even if the distillation in the crystallization step is incomplete, methylene chloride can be almost completely removed in the subsequent solid-state polymerization step.
Therefore, the aromatic polycarbonate produced in this manner contains substantially no chlorine compound derived from the chlorine-based solvent. When using a non-chlorine solvent,
As a matter of course, unless a dihydroxydiaryl compound containing a chlorine atom or a diaryl carbonate is used as a raw material, an aromatic polycarbonate containing no chlorine atom can be obtained. The term “polycarbonate-free polycarbonate” as used in the present invention means a polycarbonate having a chlorine atom content of 1 ppm or less based on the weight of the polymer.

On the other hand, the heat crystallization method is a method in which the prepolymer is crystallized by heating at a temperature above the glass transition temperature of the target aromatic polycarbonate and below the temperature at which the prepolymer begins to melt. is there. This method is suitable when a prepolymer is produced using a catalyst, and can be crystallized by simply holding the prepolymer under heating, and therefore can be carried out very easily industrially. It was entirely unexpected that relatively low molecular weight, substantially amorphous prepolymers could be crystallized by such a simple method.

As described above, the temperature Tc (° C.) at which this heat crystallization is carried out is not less than the glass transition temperature of the target aromatic polycarbonate and the melting temperature Tm of the prepolymer.
There is no particular limitation as long as it is in the range of (° C.) or less, but the crystallization rate of the prepolymer is low at low temperatures, so a particularly preferable heating crystallization temperature Tc (° C.) is represented by the formula Tm-50Tc <Tm. ) Is selected within the range indicated by.

The heat crystallization of this prepolymer may be carried out while maintaining a certain temperature in the above range constant, or may be carried out while continuously or discontinuously changing the temperature, or by combining these. It can also be carried out by another method. As the method of changing the temperature, the melting temperature of the prepolymer generally rises as the heating crystallization progresses, so heating crystallization while raising the temperature at the same rate as this rising rate. The method of causing is particularly preferable.

In this way, the method of performing heat crystallization while changing the temperature has a higher crystallization rate of the prepolymer and a higher melting temperature than the heat crystallization method at a constant temperature. The heating crystallization time varies depending on the chemical structure of the prepolymer, the presence or absence of a catalyst, the crystallization temperature, the crystallization method, etc., but is usually in the range of 1 to 200 hours.

The fact that the prepolymer that has undergone such a crystallization step is crystallized can be easily determined from the fact that the transparency of the prepolymer is lost.
It can also be confirmed by line diffraction. For example, the prepolymer obtained by carrying out the prepolymerization using bisphenol A as the dihydroxydiaryl compound, diphenyl carbonate as the diaryl carbonate, and p-tertiary butylphenol as the terminal blocking agent is amorphous and has X-ray radiation. Although no peak showing crystallinity is observed in the diffraction pattern, a crystallinity pattern having a main peak at 2θ = about 17 ° appears in the X-ray diffraction pattern of the prepolymer after the crystallization step.

Thus, by the crystallization step, the amorphous prepolymer is crystallized, the degree of crystallization, the type of dihydroxydiaryl compound and diaryl carbonate used as a raw material, the degree of polymerization of the prepolymer, Although it depends on the presence or absence of a catalyst, crystallization conditions, etc., the crystallinity is usually in the range of 3 to 75%.

It is of course possible to increase the molecular weight by the following solid phase polymerization step using the crystallized prepolymer having the crystallinity in such a range. In that case, the crystallinity is selected in the range of 5 to 55%, preferably 10 to 45%. With the crystallized prepolymer having a degree of crystallinity of less than 5%, its melting temperature does not become so high that it is melted during the solid phase polymerization to prevent solid phase polymerization, or otherwise the prepolymer is not melted. It is necessary to carry out solid-state polymerization at a relatively low temperature for an extremely long time, which is disadvantageous for industrial implementation, and if it exceeds 55%, the solid-phase polymerization rate will be slow, so it will take a long time. Solid phase polymerization,
It is disadvantageous for industrial implementation.

The crystallinity of the crystallized prepolymer referred to in the present invention means a value obtained by a usual method using powder X-ray diffraction patterns of the completely amorphous prepolymer and the crystallized prepolymer. And

In the step (c) of the method of the present invention, the crystallized prepolymer thus obtained is subjected to solid-phase polycondensation while maintaining the solid-phase state at a temperature lower than its melting temperature, whereby a high molecular weight is easily obtained. Can be an aromatic polycarbonate.

In this solid phase polymerization step, the two types of end groups present in the crystallized prepolymer, that is, the aryl carbonate end group and the hydroxyl end group, undergo polycondensation while mainly performing the following two types of reactions. It is considered to be in progress. That is, a hydroxyl end group reacts with an aryl carbonate end group to cause polycondensation while eliminating an aromatic monohydroxy compound having a hydroxyl group bonded to an aryl group based on a diaryl carbonate, and an aryl carbonate end group reacts with another aryl group. It is considered that two types of reactions, a self-condensation reaction in which polycondensation proceeds while reacting with the carbonate end group to eliminate the diaryl carbonate, occur. When diphenyl carbonate is used as the diaryl carbonate, phenol having a lower boiling point is selectively extracted from the polymerization system than the substituted phenol.

In the present invention, in the temperature range in which solid phase polymerization can be carried out,
It was found that the reaction rate of polycondensation while eliminating the aromatic monohydroxy compound is usually several times to several tens of times higher than the reaction rate of polycondensation while eliminating the diaryl carbonate.

Therefore, when solid phase polymerization is carried out using a crystallization prepolymer in which the amount of aryl carbonate end groups is higher than the amount of hydroxyl end groups, the amount of hydroxyl end groups becomes extremely small when the desired molecular weight is reached. can do. The amount of terminal hydroxyl groups of the aromatic polycarbonate produced by the method of the present invention, the molecular weight of the crystallization prepolymer used and the amount of aryl carbonate end groups, solid phase polymerization temperature, solid phase polymerization time, solid phase polymerization method, etc. It depends on the solid-state polymerization conditions, target molecular weight, etc. Usually, 0.03% by weight or less of polymer is heat resistant,
It is preferable in terms of hot water resistance.

In the solid-phase polymerization step, the reaction is promoted by extracting the aromatic monohydroxy compound (for example, phenol) and / or the diaryl carbonate, which are by-produced by the reaction, out of the system. For that purpose, nitrogen, argon, helium, an inert gas such as carbon dioxide, a method of introducing a lower hydrocarbon gas, etc., and a method of removing the diaryl carbonate and the aromatic monohydroxy compound by accompanying these gases, A method of performing the reaction under reduced pressure, a method of using these in combination, and the like are preferably used. Further, when introducing the gas for entrainment, it is preferable to heat these gases to a temperature near the reaction temperature.

There is no particular limitation on the shape of the crystallized prepolymer in the case of carrying out this solid-state polymerization reaction, but large lumps are not preferable in that the reaction rate is slow, and handling is troublesome, and pelletized, Those in the form of beads, granules, powder, etc. are suitable. Further, a crushed solid prepolymer after crystallization into an appropriate size is also preferably used. The crystallized prepolymer crystallized by the solvent treatment is usually obtained in the form of porous granules or powder, and such a porous prepolymer is an aromatic monopolymer produced as a by-product during solid phase polymerization. It is particularly preferable because the hydroxy compound and the diaryl carbonate can be easily extracted.

Regarding the reaction temperature Tp (° C.) and the reaction time when carrying out the solid-phase polymerization reaction, the type (chemical structure, molecular weight, etc.) and shape of the crystallization prepolymer, the presence or absence of a catalyst in the crystallization prepolymer, and the type Amount, type and amount of catalyst added as necessary, degree of crystallization of crystallization prepolymer, and melting temperature T
Although it depends on the difference in m '(° C), the required degree of polymerization of the target aromatic polycarbonate, or other reaction conditions, it is usually above the glass transition temperature of the target aromatic polycarbonate and the crystals during solid phase polymerization. For 1 minute to 100 hours at a temperature in the range in which the modified prepolymer does not melt and remains in a solid state, preferably in the range represented by the formula Tm'-50Tp <Tm '... (IX),
The solid phase polymerization reaction is preferably carried out by heating for about 0.1 to 50 hours.

An example of such a temperature range is bisphenol A.
When producing the polycarbonate of about 150 ~ 260 ℃
Is preferable, and about 180 to 230 ° C. is particularly preferable.

In the solid phase polymerization step, it is preferable to carry out effective agitation in order to heat the polymer being polymerized as uniformly as possible, or in order to advantageously promote the extraction of the aromatic monohydroxy compound or diaryl carbonate produced as a by-product. Is the way. As the stirring method, for example, a method using mechanical stirring such as a method using a stirring blade, a method using a reactor having a structure in which the reactor itself rotates, or a method of fluidizing with heated gas is preferably used.

When the crystallization of the prepolymer is carried out by heating crystallization, the system is depressurized or a heating gas for entrainment is added to the system following a simple heating operation for reaching a predetermined crystallinity. By introducing the aromatic monohydroxy compound or diaryl carbonate from the system, solid-phase polymerization can be carried out.

The solid-state polymerization reaction in the present invention can proceed at a sufficient rate without adding a catalyst, which is the most preferred embodiment, but a catalyst can be used for the purpose of further increasing the reaction rate. If a catalyst is used in the prepolymerization step, the catalyst usually remains in the prepolymer to be produced, so it is not necessary to add a new catalyst, but the catalyst is removed for some reason, or the activity decreases. In some cases, a suitable catalyst can be added at that time. In this case, it is also a preferable method to add the catalyst component in liquid or gas phase to the prepolymer. Examples of such a catalyst component include those described above that can be used in the prepolymerization step.

In this way, by carrying out the solid phase polymerization step, the number average molecular weight of the aromatic polycarbonate generally industrially useful, which can increase the degree of polymerization of the prepolymer, is about 3,000 to 100,000. A polycarbonate having such a polymerization degree can be easily obtained by a solid-state polymerization method of a polymer.

The polycarbonate thus obtained has a substituted phenyl carbonate group derived from the terminal blocking agent at its terminal. The concentration of this terminal group in the polymer depends on the ratio of the amount of the substituted phenol charged, the amount of the substituted phenol distilled during the polymerization, the degree of polymerization of the polymer, and the like.

For the purpose of accelerating the solid-state polymerization rate, even a small amount of the substituted phenyl carbonate group is effective,
The ratio of the substituted phenyl carbonate group is not particularly limited, but in the case of improving hot water resistance and heat resistance, it may have at least 10 mol% of the substituted phenyl carbonate groups of all terminal groups. desirable.

The shape of the aromatic polycarbonate produced by such solid phase polymerization may depend on the shape of the crystallized prepolymer used, but it is usually a so-called powder such as beads, granules, and powders. is there. Since the crystallinity of the aromatic polycarbonate obtained by solid-state polymerization of the crystallized prepolymer is usually higher than that of the original prepolymer, in the method of the present invention, the crystalline aromatic polycarbonate is usually used. A powder will be obtained.

Of course, it is also possible to introduce the crystalline aromatic polycarbonate powder, which has reached a predetermined molecular weight by solid-state polymerization, into the extruder as it is without cooling and pelletize it, or directly into the molding machine without cooling. It is also possible to mold.

The method of the present invention is a method for producing an aromatic polycarbonate having a desired average molecular weight by pre-polymerization and solid-phase polymerization, but it is possible to change the ratio of pre-polymerization and solid-phase polymerization contributing to the polymerization in a wide range. is there.

In carrying out the present invention, the type of reaction apparatus used is, in any step of prepolymerization, crystallization and solid phase polymerization, a batch system, a flow system, and a system in which these are used in combination. Either method may be used.

Also, since only a relatively low molecular weight prepolymer is produced in the prepolymerization step, an expensive reactor for high viscosity fluid such as that required for high temperature melt polymerization such as so-called transesterification method called melting method It is unnecessary. further,
In the crystallization step, the prepolymer can be crystallized simply by subjecting it to a solvent treatment or a heat treatment, so that no special device is required. Further, in the solid phase polymerization step, polymerization can be carried out as long as the apparatus can substantially heat the crystallized prepolymer and can remove the by-produced aromatic monohydroxy compound, diaryl carbonate and the like.

Such a method of the present invention can be carried out by a simple apparatus that does not require any special device, and is industrially extremely advantageous.

Further, according to the method of the present invention, aromatic polycarbonates having a small molecular weight distribution to a large one can be relatively freely produced. This is because, for example, if a prepolymer having a small molecular weight distribution is used, an aromatic polycarbonate having a small molecular weight distribution can be obtained, and if a prepolymer having a wide molecular weight distribution is used, an aromatic polycarbonate having a wide molecular weight distribution can be obtained. This is one of the great features of the present invention. The value of the ratio Mw / Mn between the weight average molecular weight (Mw) and the number average molecular weight (Mn) is usually used as a measure of the molecular weight distribution. In the case of a condensation polymer, this value is 2
Is theoretically the smallest molecular weight distribution.
It is predicted that a polymer having a small molecular weight distribution has excellent characteristics, but it is practically difficult to produce a polymer having an Mw / Mn value of 2.5 or less, particularly 2.4 or less. In an existing method, for example, a so-called transesterification method called a melting method, the reaction tends to be non-uniform because the viscosity becomes extremely remarkably high at the final stage of polymerization, and therefore it is impossible to reduce the molecular weight distribution, The polycarbonate obtained usually has Mw / Mn> 2.6. Also, in the phosgene method which is currently practiced industrially, this value is 2.4 to 3.5, and usually 2.5 to 3.2. On the other hand, according to the method of the present invention, an aromatic polycarbonate having Mw / Mn = 2.2 to 2.5 can be easily obtained. This is considered to be due to the fact that a relatively low molecular weight substance such as a prepolymer can be easily obtained with a small molecular weight distribution.

Furthermore, when an amorphous aromatic polycarbonate, for example, a polycarbonate of bisphenol A, which is the most important polycarbonate, is produced by the method of the present invention, a colorless and transparent product is obtained, which is also a great feature of the present invention.
In the so-called melting method for producing a polycarbonate of bisphenol A from bisphenol A and diphenyl carbonate, it is necessary to react a highly viscous substance under a high vacuum of 1 mmHg or less at a high temperature of around 300 ° C for a long time. Due to decomposition and a slight amount of oxygen, there was a drawback that the resulting polycarbonate was colored pale yellow by any means, but in the method of the present invention, the prepolymerization step is, for example, 250 ° C.
Hereinafter, preferably can be carried out at a relatively low temperature of 240 ℃ or less in a short time, and the crystallization step and the solid phase polymerization step,
This is because it can be carried out at a relatively low temperature of 230 ° C. or lower, so that the polymer modification as seen in the transesterification method of the melting method hardly occurs. Therefore, the crystalline polymer after solid-phase polymerization is white without yellowish color, and when this crystalline polymer is heated to a melting temperature or higher, it is easily amorphized and a colorless transparent polycarbonate of bisphenol A is obtained. can get.

In addition, chlorine-free dihydroxydiaryl compounds and diarylcarbonates also give aromatic polycarbonate powders that do not contain chlorine atoms at all, and these aromatic polycarbonate powders are particularly important as materials for optical devices and electronics. is there.

Effects of the Invention According to the method of the present invention, in the presence of a terminal blocking agent, by solid-phase polymerization using a prepolymer having a substituted phenyl carbonate end group obtained by prepolymerizing a dihydroxydiaryl compound and a diaryl carbonate, The solid-phase polymerization rate is remarkably accelerated, the polymerization can be completed in a shorter time, the deterioration of the polymer during solid-phase polymerization is reduced, and a polymer having more excellent durability is obtained.

Further, according to the method of the present invention, various substituted phenyl carbonate groups can be introduced at the polymer terminal, and it becomes possible to produce a polycarbonate having excellent fluidity, heat resistance, and hot water resistance. Polycarbonate having good fluidity is useful for various molded products, especially optical disk substrate materials.

In the phosgene method, which is an existing industrial method for producing aromatic polycarbonates, electrolytes such as sodium chloride and by-products containing chlorine are produced, and these impurities are inevitably contained in the resin. In addition, chlorine-containing compounds such as methylene chloride, which are used in large quantities as solvents, also remain in the resin. Since these impurities adversely affect the physical properties of the resin,
In the phosgene method, in order to reduce the content of these in the resin, complicated and expensive washing and removal steps are carried out, but it is impossible to completely remove these impurities.

On the other hand, in the aromatic polycarbonate obtained by the method of the present invention, since such impurities do not exist at all,
The method of the present invention is industrially advantageous because not only is it superior in quality, but, of course, a troublesome step of separating them is unnecessary.

Further, the transesterification method of the melting method requires an expensive high-viscosity reactor capable of high temperature and high vacuum, and has a drawback that the polymer is easily deteriorated by yellowing due to thermal deterioration at high temperature. This method requires no special equipment and the aromatic polycarbonate obtained is of excellent quality.

Examples Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

The molecular weight is indicated by the value of the number average molecular weight (Mn) measured by gel permeation chromatography (GPC).
Further, both of the prepolymerization reaction device and the solid-phase polymerization reaction device were designed so that deoxidation and drying were taken into consideration and oxygen and water during the reaction were mixed as little as possible.

The ratio of the aryl carbonate group and the hydroxyl group, which are the terminal groups in the prepolymer and the aromatic polycarbonate, is measured by NMR and by high performance liquid chromatography, and the method of A. Horbach (phenolic- After dissolving the prepolymer or polymer in acetic acid acid methylene chloride by the OH group quantification method,
TiCl ₄ was added, and the resulting red complex was measured by colorimetric determination with light having a wavelength of 546 nm. The crystallinity is
It is a value calculated by the above method using powder X-ray diffraction patterns of the amorphous prepolymer and the crystallized prepolymer.

Example 1 A 500 ml three-necked flask equipped with a stirrer, a gas inlet tube, and a gas outlet tube was charged with bisphenol A, ie, 2,2.
After charging 68.4 g of bis (4-hydroxyphenyl) propane and 77.0 g of diphenyl carbonate and degassing under reduced pressure and introducing dry nitrogen repeatedly to completely replace the internal atmosphere with nitrogen, the flask was heated to 180 to 190 ° C. It was immersed in an oil bath kept at room temperature and heated. When the contents were melted, degassing under reduced pressure and introduction of dry nitrogen were performed again to replace the inside with nitrogen. Then, the bath temperature was raised to 230 ° C., dry nitrogen was introduced at a rate of 30 Nl / hr for 50 minutes while stirring to remove by-produced phenol and unreacted diphenyl carbonate, and then the pressure range was 2 to 5 mmHg. Depressurize to 15
Stir for a minute. To the viscous molten polymer thus obtained, 0.18 g of p-tertiary butylphenol was added, and the mixture was stirred under a nitrogen atmosphere for another 20 minutes, and then the reaction system was gradually depressurized until it finally reached 2 mmHg. The reaction was carried out for about 20 minutes while removing the by-product phenol.

Thus, a colorless and transparent prepolymer having a number average molecular weight of about 3,800 was obtained. The end groups and analytical values of this product are shown below.

Next, this prepolymer was crushed, mixed with 250 ml of acetone and crystallized while stirring, then 20 g of the prepolymer was added to 100
Place in a ml capacity eggplant-shaped flask, depressurize to 2-5 mmHg,
Further, while introducing a small amount of dry nitrogen, it was immersed in an oil bath maintained at 190 ° C and heated at a rate of 20 ° C / hr. Once 215 ° C was reached, polymerization was carried out at this temperature for about 4 hours. In this way, a white crystalline polycarbonate powder having a number average molecular weight of about 10,800 was obtained. Table 1 shows the terminal groups and the content ratios of these.

Example 2 A crystallized prepolymer was obtained in the same manner as in Example 1 except that the amount of p-tertiary butylphenol added was changed to 0.3 g. A polycarbonate was obtained. The results are shown in Table 1.

Example 3 A crystalline polycarbonate was obtained in the same manner as in Example 1 except that the amount of p-tert-butylphenol added was changed to 0.8 g. The results are shown in Table 1.

Example 4 A crystalline polycarbonate was obtained in the same manner as in Example 1 except that the amount of p-tert-butylphenol added was changed to 1.3 g. The results are shown in Table 1.

Comparative Example 1 Bisphenol A 68.4 g, diphenyl carbonate 77.0 g
A stirrer, a gas inlet tube, a 500 ml capacity three-necked flask with a gas outlet tube was charged, vacuum degassing and dry nitrogen introduction were repeated several times, and then the flask was placed in an oil bath at 180 to 190 ° C. After soaking and melting the contents, degassing under reduced pressure and introduction of dry nitrogen were carried out. Next, the bath temperature was raised to 230 ° C, dry nitrogen was introduced at 30Nl / hr while stirring, and phenol by-produced was distilled off, and after about 50 minutes, the reaction system was depressurized to 2-5m.
Stirring at mHg for about 15 minutes produced a viscous molten polymer.

The prepolymer is then treated as in Example 1,
A crystalline polycarbonate was obtained. The results are shown in Table 1.

As is clear from Table 1, when the prepolymer was prepared in the presence of p-tertiary butylphenol, the solid phase polymerization reaction was promoted, and p was added to the end of the polycarbonate after solid phase polymerization. It can be seen that a tert-butyl phenyl carbonate group is introduced.

Example 5 Bisphenol A 68.4 g, diphenyl carbonate 77.0 g
And 0.5 g of p-tertiary butylphenol were placed in a 500 ml three-necked flask equipped with a stirrer, a gas inlet tube, and a gas outlet tube, and deaeration under reduced pressure and introduction of dry nitrogen were repeated several times, and then the flask was heated to 180 After immersing the contents in an oil bath at ˜190 ° C. to melt the contents, deaeration under reduced pressure and introduction of dry nitrogen were performed. Then the bath temperature
The temperature was raised to 200 ° C., and while stirring, dry nitrogen was introduced at 20 Nl / hr to distill off by-produced phenol. Further, the bath temperature was gradually raised from 200 ° C to 230 ° C, and phenol was distilled off. After about 80 minutes, depressurize the reaction system to about 15 at 2-5 mmHg.
Stirring for a minute produced a viscous molten polymer.

The prepolymer thus obtained was crystallized in the same manner as in Example 1, and then solid phase polymerization was performed. The results are shown in Table 1. As can be seen from Table 1, the solid phase polymerization time was shortened.

Example 6 The procedure of Example 1 was repeated, except that 0.6 g of 4- (1,1,3,3-tetramethylbutyl) phenol was used instead of 0.3 g of p-tert-butylphenol. To obtain a polycarbonate. The results are shown in Table 2.

This polycarbonate had a melt viscosity at 280 ° C. and 160 kg / cm ² measured by a Koka type flow tester which was 20% lower than that of the polycarbonate of Comparative Example 1 having almost the same number average molecular weight.

Example 7 A polycarbonate was obtained in the same manner as in Example 1 except that 0.6 g of p-tertiary octylphenol was used in place of 0.3 g of p-tertiary butylphenol. The results are shown in Table 2.

This polycarbonate has excellent resistance to hot water at 120 ° C. and has almost the same number average molecular weight. Comparative Example 1
It was superior to the above polycarbonate with less generation of craze.

Example 8 A polycarbonate was obtained in the same manner as in Example 1 except that 0.5 g of p-cumylphenol was used instead of 0.3 g of p-tert-butylphenol. The results are shown in Table 2.

It was confirmed by ¹ H-NMR that this polycarbonate had a p-cumylphenyl carbonate group introduced at the terminal.

Example 9 A polycarbonate was obtained in the same manner as in Example 1 except that 0.3 g of α-naphthol was used instead of 0.3 g of p-tert-butylphenol. The results are shown in Table 2.

It was confirmed by ¹ H-NMR that a naphthyl carbonate group was introduced at the terminal of this polycarbonate.

Example 10 A polycarbonate was obtained in the same manner as in Example 1 except that 0.9 g of octadecyloxyphenol was used instead of 0.3 g of p-tert-butylphenol. The results are shown in Table 2.

It was confirmed by ¹ H-NMR that the polycarbonate had an octadecyloxyphenyl carbonate group introduced at the terminal.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Haruyuki Yoneda Inventor Haruyuki Yoneda 3-13-1, Shiodo, Kurashiki-shi, Okayama Asahi Kasei Kogyo Co., Ltd. (56) Reference JP-A-632223035

Claims (1)

[Claims] 1. A dihydroxydiarylalkane represented by the general formula HO-Ar ¹ -Y-Ar ² -OH (wherein Ar ¹ and Ar ² are each an arylene group and Y is an alkylene group or a substituted alkylene group). In the production of an aromatic polycarbonate by reacting a dihydroxy diaryl compound mainly composed of with a diaryl carbonate, (a) in the presence of at least one terminal blocker selected from a nucleus-substituted phenol compound and a naphthol compound. , The dihydroxy diaryl compound and the diaryl carbonate are heated and reacted to give a number average molecular weight of 1,000 to 1
Prepolymerization step to form 0,000 prepolymer, (b) crystallization step to crystallize the prepolymer obtained in step (a) to form a crystallized prepolymer, and (c) obtained in step (b) The crystallized prepolymer, which is higher than the glass transition temperature of the aromatic polycarbonate produced,
In addition, an aromatic polycarbonate having a nucleus-substituted phenyl carbonate group at the end is characterized in that the crystallized prepolymer is heated to a temperature in a range where the solid phase can be maintained, and a solid phase polymerization step for further increasing the polymerization degree is sequentially performed. Production method.