JP2003226751A - High purity diphenyl carbonate composition and method for producing polycarbonate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a high purity diphenyl carbonate composition which has reduced discoloration, and can be advantageously used in the production of a high-molecular weight polycarbonate. <P>SOLUTION: The high purity diphenyl carbonate comprises methylphenylphenyl carbonate, and has a content of the methylphenylphenyl carbonate of ≤300 wt.ppm, and the total content of impurities including the methylphenylphenyl carbonate of ≤1 wt.% with the rest being diphenyl carbonate, reduces discoloration, and can be advantageously used in the production of a high-molecular weight polycarbonate. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a high-purity diphenyl carbonate composition and a method for producing the same, and more particularly to a high-purity diphenyl carbonate composition utilizing a plurality of purification steps from a reaction product of a de-CO reaction of diphenyl oxalate. Regarding how to get.
The present invention further relates to a polycarbonate having a high molecular weight and little coloring, and a method for producing the same.

Diphenyl carbonate is known as a raw material compound in various chemical reactions, and it is well known that a polycarbonate can be obtained by a polycondensation reaction with an aromatic dihydroxy compound. Since this polycarbonate is excellent in mechanical strength, transparency, electrical characteristics, optical characteristics, etc., it is useful as a forming material for electric / electronic products such as compact discs, organic glass, and industrial material products such as optical lenses. It is a very important polymer.

[0003]

BACKGROUND OF THE INVENTION It is known that diphenyl carbonate can be produced by a diphenyl carbonate synthesis reaction such as a phosgene method, a method by transesterification of dimethyl carbonate, and a method by a CO removal reaction of diphenyl oxalate. Among them, the method of producing diphenyl carbonate from diphenyl oxalate in a liquid phase by a CO removal reaction is useful as an industrial production method. For example, in the presence of a CO removal catalyst such as an organic phosphorus compound, a diaryl oxalate (oxalic acid A method of producing a diaryl carbonate (such as diphenyl carbonate) together with carbon monoxide by heating (e.g. diphenyl) to remove CO is disclosed in JP-A 8-333307, JP-A 10-59905, and JP-A 11-59905. It is disclosed in Japanese Patent Publication No. -152252.

It is well known that a polycarbonate can be produced by subjecting diphenyl carbonate obtained by a synthetic reaction of diphenyl carbonate to a polycondensation reaction with an aromatic dihydroxy compound. For example, it is possible to produce a polycarbonate by using diphenyl carbonate obtained by subjecting diphenyl oxalate to a CO deoxidization reaction in the presence of a CO decatalyst together with an aromatic dihydroxy compound as a raw material monomer, and carrying out a polycondensation reaction of both. , JP-A-1
No. 0-152552, Japanese Patent Application Laid-Open No. 10-152253, WO98 / 54240 and the like.

[0005]

The crude diphenyl carbonate raw material obtained by a known diphenyl carbonate synthesis reaction such as a phosgene method, a method by transesterification of dimethyl carbonate, a method by a de-CO reaction of diphenyl oxalate, etc. It was found in the course of research by the present inventors that impurities such as methylphenylphenyl carbonate are contained due to cresol mixed in phenol as a starting material.

Impurities such as the above-mentioned methylphenylphenyl carbonate are derived from cresol contained as an impurity in phenol used as an industrial product, and when diphenyl oxalate derived from phenol is used as a raw material to produce diphenyl carbonate, It is understood to form together with the desired product, diphenyl carbonate, depending on the cresol content in the phenol.

[0007] For example, decarbonization containing diphenyl carbonate as a main component, which is obtained by a CO removal reaction of diphenyl oxalate.
In the evaporative components obtained by evaporating the O reaction liquid with an evaporator,
In addition to the desired product diphenyl carbonate and the unreacted starting material diphenyl oxalate, a considerable amount of impurities such as methylphenylphenyl carbonate are included. In fact, the boiling point of methylphenylphenylcarbonate is about 315 ° C at atmospheric pressure,
Since it is very close to the boiling point of the target diphenyl carbonate (about 304 ° C. at normal pressure), it was difficult to efficiently separate methylphenylphenyl carbonate from diphenyl carbonate by a simple distillation operation.

According to the research conducted by the present inventor, when a polycarbonate is produced using diphenyl carbonate in which impurities such as methylphenylphenyl carbonate (particularly o-methylphenylphenyl carbonate) are mixed in a certain amount or more, the obtained polycarbonate is sufficient. It was found that it did not show a high molecular weight and was easily colored yellow.

The object of the present invention is to provide a high-purity diphenyl carbonate composition and a method for producing the same. And an object of the present invention is to provide a method for obtaining a high-purity diphenyl carbonate composition from a reaction product of a CO removal reaction of diphenyl oxalate by utilizing a plurality of purification steps. Another object of the present invention is to provide a polycarbonate having a high molecular weight and less coloring, and a method for producing the same.

[0010]

The present invention contains methylphenylphenyl carbonate (particularly o-methylphenylphenyl carbonate; hereinafter the same) (however, it contains more than 0 ppm by weight; hereinafter the same). A pure diphenyl carbonate composition having a methylphenylphenyl carbonate content of 3
00 weight ppm or less (preferably 1 to 300 weight pp
m), and the total content of impurities including methylphenylphenyl carbonate is 1% by weight or less, and the balance is diphenyl carbonate.

The high-purity diphenyl carbonate composition of the present invention comprises
A high-purity diphenyl carbonate composition containing methylphenylphenyl carbonate, wherein the content of methylphenylphenyl carbonate is 200 ppm by weight or less (more preferably 10-2).
It is preferable that the total content of impurities including methylphenylphenyl carbonate is 0.5% by weight or less and the balance is diphenyl carbonate.

Examples of impurities other than methylphenylphenyl carbonate contained in the high-purity diphenyl carbonate composition of the present invention include phenyl benzoate, the content of which is 100 ppm by weight based on the diphenyl carbonate composition.
It is preferably the following (particularly 50 ppm by weight or less, more preferably 0.1 to 50 ppm by weight). Examples of other impurities include benzofuran-2,3-dione, the content of which is 1 wtppm or less (particularly 0.8 wtppm or less, further 5 wtp or less with respect to the diphenyl carbonate composition.
pb to 0.5 ppm by weight) is preferable.

The high-purity diphenyl carbonate composition of the present invention comprises
It is preferably obtained by purifying the reaction product of the deCO reaction of diphenyl oxalate. This diphenyl oxalate is a diphenyl oxalate derived from phenol mixed with cresol (particularly o-cresol).

That is, the high-purity diphenyl carbonate composition of the present invention is prepared by distilling a crude diphenyl carbonate composition containing impurities containing methylphenylphenyl carbonate to obtain low-boiling impurities (low-boiling fractions) and high-boiling impurities. (High-boiling point residue) is removed to obtain a crude fraction containing a high concentration of diphenyl carbonate, and then light impurities are further removed from the crude fraction by distillation, and then the residue (light impurities are removed. It can be obtained by distilling the obtained crude fraction) to remove methylphenylphenyl carbonate from the residue. This crude diphenyl carbonate composition is de-CO2 obtained by de-CO reacting diphenyl oxalate derived from phenol mixed with cresol (particularly o-cresol) in the presence of a de-CO catalyst containing an organic phosphorus compound. It is preferably obtained by evaporating the reaction liquid.

In the above method, the crude fraction is 50-50.
It contains methylphenylphenyl carbonate in an amount in the range of 00 ppm by weight, and the diphenyl carbonate content is 9
It is preferably 5.0% by weight or more.

In the above process, the residue (crude fraction from which light impurities have been removed) contains methylphenylphenyl carbonate in an amount ranging from 50 to 2500 ppm by weight, and the diphenyl carbonate content is 98. It is preferably 0% by weight or more.

In the above method, the light impurities removed from the crude fraction by distillation are preferably those having benzofuran-2,3-dione as a main component.

The present invention also resides in a method for producing a polycarbonate, which comprises subjecting the above-mentioned high-purity diphenyl carbonate composition and an aromatic dihydroxy compound to a polycondensation reaction in the presence of a transesterification catalyst.

The polycarbonate of the present invention preferably has an average molecular weight of 14,000 or more and a yellow coloring degree of b value of 0.9 or less, and particularly has an average molecular weight of 14,500.
As described above, the degree of yellow coloring is preferably 0.8 or less as the b value. The polycarbonate of the present invention having such excellent properties can be obtained by subjecting the high-purity diphenyl carbonate composition and an aromatic dihydroxy compound to a polycondensation reaction in the presence of a transesterification catalyst.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the drawings. In the following description, unless otherwise stated, the unit (%, ppm, ppb) when indicating the content or concentration of impurities such as methylphenylphenyl carbonate or diphenyl carbonate is based on weight. FIG. 1 is a flow chart illustrating the outline of the method for obtaining the high-purity diphenyl carbonate composition of the present invention, and FIG. 2 shows the method for obtaining the high-purity diphenyl carbonate composition of the present invention.
FIG. 3 is a process diagram showing an example in which removal of methylphenylphenylcarbonate is performed by distillation of a crude fraction.

In the method for obtaining the high-purity diphenyl carbonate composition of the present invention, as the crude diphenyl carbonate raw material, there are known carbonates such as a phosgene method, a method by transesterification of dimethyl carbonate, and a method by a de-CO reaction of diphenyl oxalate. A diphenyl carbonate crude material (diphenyl carbonate synthesis reaction solution) obtained by the diphenyl synthesis reaction,
Diphenyl carbonate containing at least impurities such as methylphenylphenyl carbonate is used.

The synthesis of diphenyl carbonate by the CO removal reaction of diphenyl oxalate is usually carried out in the presence of a CO removal catalyst according to the following reaction formula (Ph is a phenyl group). The diphenyl oxalate is diphenyl oxalate derived from phenol mixed with cresol (particularly o-cresol).

[0023]

[Chemical formula 1] (COOPh) ₂ → CO (OPh) ₂ + CO

The CO removal reaction of diphenyl oxalate is carried out in the liquid phase in the presence of a CO removal catalyst containing an organic phosphorus compound such as a phosphonium salt, and as shown in the above reaction formula, diphenyl oxalate is converted to diphenyl carbonate. Carbon monoxide (gas)
And generate. The carbon monoxide produced by the CO removal reaction becomes a gas and is discharged to the outside of the reaction system, but if necessary, it can be purified and reused as a CO raw material.

As the phosphonium salt used as a catalyst in the CO removal reaction, known compounds can be used. The phosphonium salt may be a single type or a mixture of two or more types. The CO-free catalyst is uniformly dissolved in the CO-free reaction liquid and may be partially suspended. The amount of the phosphonium salt used (the amount supplied to the CO-free reaction system) is preferably 0.001 to 50 mol% with respect to the diphenyl oxalate supplied to this reaction system.

In the method for obtaining a high-purity diphenyl carbonate composition of the present invention, first, in the evaporation step, the crude diphenyl carbonate raw material (diphenyl carbonate synthesis reaction liquid) is evaporated to diphenyl carbonate, diphenyl oxalate, methylphenylphenyl carbonate. A crude diphenyl carbonate composition (evaporating component) containing, for example, is obtained and supplied to the purification step. For example,
By evaporating the de-CO reaction liquid obtained by the synthesis of diphenyl carbonate by the de-CO reaction of diphenyl oxalate as described above, an un-evaporated component mainly containing a de-CO catalyst component and a high-boiling substance (high-boiling impurity) And evaporative components mainly containing diphenyl carbonate (substantially not containing the de-CO catalyst component), and the evaporative components (mixed vapor) are recovered and supplied to the distillation purification step.

The above-mentioned diphenyl carbonate synthesis reaction solution is decarbonized.
It contains unreacted raw materials and by-products along with the O catalyst component and the desired product, diphenyl carbonate. For example, the above-mentioned CO-free reaction liquid is a CO-free catalyst component (known halogen compound (particularly chloro compound)) derived from a CO-free catalyst containing diphenyl carbonate as a target product, diphenyl oxalate as a raw material, and an organic phosphorus compound. Auxiliaries may be added), by-products (high-boiling by-products, low-boiling by-products), etc. are contained (content of diphenyl carbonate is preferably 50).
~ 95%). Since carbon monoxide (gas) generated by the CO-free reaction is naturally gas-liquid separated from the CO-free reaction solution and discharged, it is not substantially contained in the CO-free reaction solution.

In the above-mentioned step of evaporating the CO-free reaction solution, first, the target product diphenyl carbonate and a low boiling point substance are contained, and further other components (high boiling point substances such as diphenyl oxalate) which evaporate together with diphenyl carbonate are also added. The evaporation component (mixed vapor) contained in a small amount is removed by evaporating it under the conditions of a temperature (about 100 to 250 ° C.) and a reduced pressure (particularly about 0.1 to 50 kPaA) which are similar to the reaction temperature in the CO removal reaction. Recover from CO reaction. Then, the evaporation component (mixed vapor) obtained in this evaporation step is subjected to the next distillation purification.

The evaporative component preferably has a diphenyl carbonate content of about 70 to 95% and a diphenyl oxalate content of 5 to 25%.
Furthermore, the total content of diphenyl carbonate and diphenyl oxalate is preferably 80 to 99.9%, and more preferably 85 to 99.9%. Further, the evaporation component contains a low boiling point substance (low boiling point impurity, light impurity) having a lower boiling point than diphenyl carbonate, and further contains a small amount of a high boiling point substance (high boiling point impurity) having a higher boiling point than diphenyl carbonate, etc. It is preferable that the content ratio of all components constituting the balance except diphenyl carbonate and diphenyl oxalate is about 0.1 to 5%. The amount of the de-CO catalyst component in the vaporized component is extremely small or substantially absent.

In the above evaporation step, together with the evaporation / recovery of the evaporation component (mixed vapor) described above, together with the CO-free catalyst component,
The residual liquid (concentrated liquid) of the de-CO reaction liquid consisting of unevaporated components mainly containing the target product diphenyl carbonate and high-boiling substances (high-boiling impurities: unreacted diphenyl oxalate and high-boiling by-products) is collected. . If necessary, this residual liquid can be withdrawn from the bottom of the evaporator and circulated to the CO-free reaction system to reuse the CO-free catalyst component in the liquid.

The evaporation process of the CO-free reaction solution is as follows.
CO removal derived from a CO removal catalyst containing diphenyl carbonate, which is the target product in the CO removal reaction, and an organic phosphorus compound
Since the main purpose is to obtain an evaporation component (mixed vapor) containing diphenyl carbonate as a main component, which does not contain a CO-free catalyst component, by separating the catalyst component by an evaporation operation, this object can be achieved. If possible, the evaporation method and the evaporation means (evaporation device) are not particularly limited. However, in the present invention, it is preferable to perform the evaporation operation using an evaporator (evaporator) such as a falling film evaporator or a thin film evaporator.

Next, in the first distillation / purification step, the evaporation component (mixed vapor), which is the crude diphenyl carbonate composition obtained in the above-mentioned evaporation step, is purified by distillation to obtain low-boiling impurities of the low-boiling substances. And high-boiling substances (high-boiling impurities: diphenyl oxalate and high-boiling by-products) are sequentially removed to obtain a crude fraction consisting of high-concentration diphenyl carbonate containing a slight amount of impurities such as methylphenylphenyl carbonate.

The above-mentioned low-boiling substance means a compound having a boiling point lower than that of diphenyl carbonate, and examples thereof include low-boiling impurities such as phenol compounds (particularly phenol and cresol) and furan compounds. Mention may be made of light impurities such as (especially benzofuran-2,3-dione).

The above-mentioned high-boiling substance (high-boiling impurity) means a compound having a boiling point higher than that of diphenyl carbonate. For example, diphenyl oxalate or methyl oxalate which is a raw material for the CO-elimination reaction. High boiling by-products such as phenyl phenyl, methyl phenyl phenyl carbonate and phenyl p-chlorobenzoate can be mentioned.

In the above-mentioned distillation purification, most of low-boiling point impurities and high-boiling point impurities are sequentially removed from the evaporating components by the above-mentioned distillation operation of the evaporating components to obtain a crude fraction containing a high concentration of diphenyl carbonate. For example, first, by the first distillation operation of the evaporation component, a low-boiling fraction (distillation fraction of the first distillation operation) consisting of diphenyl carbonate containing low-boiling impurities such as phenolic compounds is extracted and removed, and , The low-boiling-point impurities obtained in the first distillation operation were almost removed, and the residue consisting of high-concentration diphenyl carbonate containing high-boiling-point impurities (residue from the first distillation operation) was extracted, and then the residue By distilling the fractions again, a crude fraction with a high content of diphenyl carbonate can be obtained. On the other hand, it is preferable that the bottom liquid of this distillation column (diphenyl oxalate, diphenyl carbonate, high-boiling point residue containing high-boiling by-products) is purged or circulated to the CO-free reaction system.

The above crude fraction has a diphenyl carbonate content of 95.0% or more (particularly about 96.0 to 99.9% by weight) and a methylphenylphenyl carbonate content of 50 to 50%. 5000 ppm, especially 100-3000
The content of diphenyl oxalate is 10 ppm to
1%, especially about 10 to 2000 ppm, and the content of high boiling by-products such as phenyl p-chlorobenzoate is 10 to 20.
The content of light impurities such as furan compounds (especially benzofuran-2,3-dione) is 1 to 2000 ppm, especially 1 to 1
It is preferably about 000 ppm.

The crude fraction obtained by the above-mentioned distillation operation of the vaporized components is then subjected to various removal means for removing light impurities such as furan compounds in the light impurity removal step to obtain a crude fraction. Light impurities can be substantially removed from the cut.

The means for removing the light impurities from the crude fraction is preferably (a) the distillation operation of the crude fraction (distillation-removal method), and (b) the light impurities are mainly furan-based. When it is a compound, it can also be carried out by the heat treatment (pyrolysis-removal method) of the above-mentioned crude fraction.

That is, the light impurities such as the furan compounds are removed by removing the light impurities from the high-concentration diphenyl carbonate crude fraction obtained by the distillation operation of the evaporation component. By performing a distillation operation, the distillate containing a very high concentration of light impurities at a content of about 1 to 1000 ppm (diphenyl carbonate content of 98 to 99.9% by weight) is used as a light impurity. On the other hand, high concentration diphenyl carbonate (carbonic acid having a low content rate of 50 to 2500 ppm of methylphenylphenyl carbonate and 1 ppm or less of light impurities, especially 5 ppb to 0.8 ppm, further 5 ppb to 0.5 ppm) was taken out and removed. Diphenyl content is 98.
It is particularly preferable to use a means for removing light impurities (distillation-removal method) by only a distillation operation to obtain a residue consisting of 0% by weight or more, particularly about 99.0 to 99.9% by weight.

When the light impurities are mainly furan compounds, the crude fraction obtained by the distillation operation of the evaporation component is heat-treated at a temperature of 150 to 300 ° C. for about 0.05 to 10 hours to give benzofuran-2. It is also possible to use a removing means (heat treatment-removal method) comprising heat treatment of thermally decomposing, condensing and / or thermally denaturing a furan-based compound such as 1,3-dione.

Next, in the second distillation and purification step, the residue (comprising the removal of the light impurities) of high concentration of diphenyl carbonate obtained by the various removal means for removing the above-mentioned light impurities (such as the distillation operation). Is a high-purity diphenyl carbonate composition containing methylphenylphenyl carbonate (containing more than 0 ppm), wherein the content of the methylphenylphenyl carbonate is 300 ppm. Below (preferably 1 to
300 ppm), especially 200 ppm or less, further 10 to 2
00 ppm, and 99.0% or more of diphenyl carbonate, particularly 99.5% or more, and further 99.500 to 99.9.
A fraction (product; high-purity diphenyl carbonate composition) consisting of high-purity diphenyl carbonate contained in a proportion of 99% can be obtained.

That is, the high-purity diphenyl carbonate composition of the present invention is a high-purity diphenyl carbonate composition containing methylphenylphenyl carbonate (in particular, o-methylphenylphenyl carbonate) (more than 0 ppm). The content of methylphenylphenyl carbonate is 300 ppm by weight or less (preferably 1 to 300 ppm), the total content of impurities including methylphenylphenyl carbonate is 1% by weight or less, and the balance is diphenyl carbonate. Among them, especially, the content rate of methylphenylphenyl carbonate is 20.
It is preferably 0 ppm by weight or less (more preferably 10 to 200 ppm), the total content of impurities including methylphenylphenyl carbonate is 0.5% by weight or less, and the balance is diphenyl carbonate.

The product (high-purity diphenyl carbonate composition) composed of high-purity diphenyl carbonate obtained by the above method is
Light impurities such as furan compounds, which are impurities other than methylphenylphenyl carbonate (especially benzofuran-2,3
-Dione) content is less than 1 ppm, especially 0.8 ppm
Hereafter, it is preferable that the amount is about 5 ppb to 0.5 ppm. When analyzing impurities, concentrate the product if necessary.

Further, in the above-mentioned high-purity diphenyl carbonate product, the content of phenyl benzoate, which is another impurity, is 100 ppm or less, particularly 50 ppm or less, and further 0.1 to 0.1 ppm.
It is preferably about 50 ppm, and the content of the hydrolyzable halogen compound (hydrolyzable organic halogen compound or inorganic halogen compound) is as chlorine content.
1 ppm or less, especially 1 ppb to 1 ppm, and further 1 ppb
It is preferably about 0.5 ppm. This hydrolyzable halogen compound can be analyzed according to the method described in JP-B-6-18868.

In the second distillation purification step, when the means for removing light impurities is a distillation-removal method, the above-mentioned residue consisting of high-concentration diphenyl carbonate is separated by the first distillation purification (first distillation purification). Since it contains methylphenylphenyl carbonate and other high-boiling-point impurities that could not be removed (for example, phenyl p-chlorobenzoate), they are removed by performing distillation purification (second distillation purification) again. The above-mentioned high-purity diphenyl carbonate composition.

In this case, the content of the organic chlorine compound such as phenyl p-chlorobenzoate in the high-purity diphenyl carbonate composition can be reduced to 3 ppm or less, particularly 1 ppm or less in terms of chlorine content.

In the second distillation purification step, when the means for removing light impurities is a pyrolysis-removal method, the heat-treated crude fraction contains methylphenylphenyl carbonate and other high-boiling impurities. Therefore, a high-purity diphenyl carbonate composition can be obtained in the same manner by subjecting the above-mentioned crude fraction to the heat treatment of the crude fraction to remove them, followed by a distillation operation.

The high-boiling point impurities other than the above-mentioned methylphenylphenyl carbonate include, for example, (a) high-boiling point impurities produced by condensation and / or thermal denaturation of furan-based impurities, and (b) phenyl p-chlorobenzoate. Examples of the high-boiling-point impurities such as organic chlorinated compounds, etc., which are produced during the de-CO reaction and are mixed in the crude fraction.

That is, in the production of the high-purity diphenyl carbonate composition of the present invention, as shown in FIG. 1, in the first step (CO removal reaction step), diphenyl oxalate is subjected to CO removal reaction in the liquid phase to produce diphenyl carbonate. The second step (evaporation step)
Then, the evaporated CO-containing reaction liquid obtained in the first step is subjected to an evaporation operation to separate and recover the evaporated component containing diphenyl carbonate, and the third step (first distillation purification step) obtains it in the second step. A low-boiling fraction containing low-boiling impurities and a high-boiling residue containing high-boiling impurities are sequentially removed by first distilling and refining the evaporated components to obtain a crude distillate consisting of high-concentration diphenyl carbonate. Then, in the fourth step (light impurity removal step), an operation of removing light impurities from the crude fraction obtained in the second step is used.

Then, the crude fraction from which the light impurities have been removed (for example, the crude fraction from which the light impurities have been removed by the above-mentioned distillation-removal method), that is, the residual fraction, is as shown in FIG. In the fifth step (second distillation purification step), in order to obtain high-purity diphenyl carbonate having a low impurity content by removing high-boiling impurities such as methylphenylphenyl carbonate (compound having a higher boiling point than diphenyl carbonate) It is preferable to carry out the distillation purification.

When the means for removing the light impurities is a distillation-removal method, for example, as shown in FIG. 2, in the first step (CO removal reaction step), a CO removal catalyst containing an organic phosphorus compound is removed. The catalyst supply line (1) is supplied to the CO removal reactor (3), and diphenyl oxalate is supplied from the diphenyl oxalate supply line (2) to the CO removal reactor (3).
To a reaction temperature of 100 to 450 ° C. (particularly 160 to 400 ° C., more preferably 180 to 350).
℃), reaction pressure 10 mmHg to 10 kg / cm ₂ (especially under a pressure near normal pressure), and reaction time of about 0.5 to 20 hours (especially 1 to 10 hours) in a liquid phase, and a reaction by-product thereof. While the carbon monoxide (CO), which is a CO2, is being discharged from the CO discharge line (8) to the outside of the reaction system, the CO-free reaction liquid is withdrawn from the reactor (3) and then the second CO The method of supplying to the evaporation process of a process is utilized.

In the above-mentioned CO removal reaction, if necessary, as shown in FIG. 2, residual CO removal reaction liquid extracted from the evaporator (5) for performing the evaporation operation of the CO removal reaction liquid. The liquid (concentrated liquid; containing the de-CO catalyst component derived from the organic phosphorus compound) is decarbonized via the concentrated liquid line (6).
It is preferable to supply it to the O reactor (3), and at that time, together with the diphenyl oxalate, the CO-eliminating catalyst component, and the residual liquid (concentrated liquid), a halogen compound (particularly a chloro compound) is Feeding to the reactor (3) via the feed line (10) is preferable in maintaining the de-CO catalyst activity.

In the second step (evaporation step), as shown in FIG. 2, the CO-free reaction liquid supplied through the reaction liquid line (4) is heated under reduced pressure in the evaporator (5) to obtain carbon dioxide. It is possible to evaporate diphenyl, diphenyl oxalate and the like, and supply the vaporized components to the first distillation purification step of the third step via the vaporized component line (9).

In the second step, the evaporator (5) described above is used.
The non-evaporated components of the de-CO reaction liquid that did not evaporate in step (3) were withdrawn from the evaporator (5) as a residual liquid (concentrated liquid), and if necessary, most of the residual liquid containing the catalyst component (extracted from the evaporator) 90 to 99.9% of the residual liquid may be circulated to the reactor (3) in the above-mentioned first step (de-CO reaction step) via the concentrate line (6) to reuse the de-CO catalyst component. , Particularly preferred. However, since the residual liquid contains a high proportion of impurities having a high boiling point, a part of the residual liquid (preferably 0.0% of the residual liquid extracted from the evaporator) is used.
It is preferable that the content (concentration) of the high-boiling point impurities in the CO removal reactor described above is appropriately adjusted by purging (1 to 10%) from the purge liquid line (7) to the outside of the system.

In the third step (first distillation purification step), for example, as shown in FIG. 2, the evaporation component supplied from the evaporator (5) via the evaporation component line (9) is first converted into the first evaporation component.
It is supplied to a distillation column (11) and purified by distillation, while a low boiling point fraction containing low boiling point impurities contained in the evaporation component is withdrawn from the top of the column, and a residual fraction (can solution) from the bottom of the column.
Is supplied to the next second distillation column (12) to be further purified by distillation, while the residue containing high-boiling point impurities is withdrawn from the bottom of the column through the high-boiling point residue line (17),
On the other hand, the crude fraction line (1
From 9), a crude fraction composed of high-concentration diphenyl carbonate from which low-boiling impurities and high-boiling impurities are considerably removed is extracted and supplied to the next fourth step (light impurity removing step). Since the bottom liquid extracted from the line (17) contains unreacted diphenyl oxalate, the CO removal reactor (3)
It is preferable to circulate to

In the fourth step, as shown in FIG. 2, the crude fraction is fed to the light impurity removal column (13) and subjected to a distillation operation to obtain a fraction containing light impurities (light impurity fraction). ) Can be removed from a light impurity fractionation line (15) connected to the top of the light impurity removal column (13).

On the other hand, in the distillation operation in the above-mentioned light impurity removal column, the residue (container liquid) containing high-purity diphenyl carbonate from which light impurities have been substantially removed is passed from the bottom of the column via line (20). It is extracted and the high-purity diphenyl carbonate is supplied to the fifth step (second distillation purification step). When the light impurity fraction withdrawn from the light impurity fraction line (15) contains a large amount of diphenyl carbonate, this fraction may be circulated to the CO removal reactor (3).

In the above-mentioned fifth step (second distillation purification step), as shown in FIG. 2, the high-concentration diphenyl carbonate supplied from the bottom of the light impurity removal column (13) via the line (20) was added. , A diphenyl carbonate purification tower (14; also referred to as a DPC purification tower), and a high-purity diphenyl carbonate fraction (high-purity diphenyl carbonate in which residual high-boiling impurities such as methylphenylphenyl carbonate are removed from the top of the tower ( Product)
Can be obtained via line (16).

On the other hand, in the distillation operation in the above-mentioned DPC purification column (14), the residue (bottom liquid) containing high-boiling impurities from the bottom of the column is passed through the high-boiling substance line (1).
8) Pull out via.

The high-purity diphenyl carbonate of the present invention does not contain methylphenylphenyl carbonate in an amount exceeding 300 ppm and is a high-purity diphenyl carbonate having a diphenyl carbonate content of 99.0% or more. It can be preferably used as a monomer raw material for producing a polycarbonate by polycondensing an aromatic dihydroxy compound and diphenyl carbonate in the presence of.

That is, as the diphenyl carbonate used in the above-mentioned polycarbonate production method (polycondensation reaction), the methylphenylphenyl carbonate obtained by the CO removal reaction of diphenyl oxalate exceeds 300 ppm, and particularly 200 ppm.
Diphenyl carbonate, which does not contain more than 99.
High-purity diphenyl carbonate, which is contained at a content of 0% or more, particularly 99.5% or more, is preferable because a polycarbonate having stable molecular weight and other qualities can be obtained with good reproducibility.

The diphenyl carbonate used in the polycondensation reaction exceeds 1 ppm of light impurities such as furan-based impurities (especially benzofuran-2,3-dione), and particularly 0.8
High-purity diphenyl carbonate, which does not contain more than ppm, does not adversely affect the quality of the obtained polycarbonate, such as coloring, and is therefore preferable.

Further, the diphenyl carbonate used in the polycondensation reaction exceeds 100 ppm of phenyl benzoate,
In particular, high-purity diphenyl carbonate, which does not contain more than 50 ppm, enables the above-mentioned polycondensation reaction to be carried out stably, and a polycarbonate of stable quality can be produced with good reproducibility. Therefore, it is particularly preferable.

The aromatic dihydroxy compound used in the polycondensation reaction is an aromatic hydroxy compound having two hydroxy groups directly bonded to the aromatic ring of the aromatic compound, preferably 80 to 100 mol%. Is preferably contained in a proportion of 90 to 100 mol%.

The aromatic dihydroxy compound is an aromatic hydrocarbon dihydroxy compound having two hydroxy groups (for example, an aliphatic diol compound such as ethylene glycol, propylene glycol, butanediol or hexanediol) as described above. May be partially used together with.

Specific examples of the aromatic dihydroxy compound include bis (4-hydroxyphenyl) methane and 1,1-
Bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4
-Hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane, 2,2-bis (4-hydroxy-2-methylphenyl) propane, 1,1-bis (4-hydroxy-2-t-butylphenyl) Propane, bis (hydroxyaryl) alkanes such as 2,2-bis (4-hydroxy-3-bromophenyl) propane, [the above compounds are also referred to as bisphenol compounds], 4,4′-dihydroxydiphenyl ether,
Dihydroxy aryl ethers such as 4,4′-dihydroxy-3,3′-dimethyldiphenyl ether,
4,4'-dihydroxydiphenyl sulfide, 4,
Dihydroxyaryl sulfides such as 4′-dihydroxy-3,3′-dimethyldiphenyl sulfide,
4,4'-dihydroxydiphenyl sulfoxide, 4,
Dihydroxyaryl sulfoxides such as 4′-dihydroxy-3,3′-dimethyldiphenyl sulfoxide, 4,4′-dihydroxydiphenyl sulfone, 4,
Examples thereof include dihydroxyaryl sulfones such as 4′-dihydroxy-3,3′-dimethyldiphenyl sulfone.

In the production of polycarbonate, the high-purity diphenyl carbonate composition contains 1.001 to 1.5 mol, particularly 1.01 to 1.5 mol, per 1 mol of the aromatic dihydroxy compound.
It is preferably used in an amount of 1.3 moles, and in addition to the above-mentioned high-purity diphenyl carbonate and aromatic dihydroxy compound, a suitable polymerization regulator, terminal modifier, monophenol, etc. may be used in combination. Good.

In the production of polycarbonate, a high-purity diphenyl carbonate composition and an aromatic dihydroxy compound are added,
Suitable basic catalysts (eg, alkali metal or alkaline earth metal organic acid salts, inorganic acid salts, hydroxides, hydrides,
Alcohol or a nitrogen-containing basic compound) at a temperature of about 100 to 330 ° C. while evaporating and removing the by-produced phenol compound, and gradually increasing the polymerization temperature and increasing the degree of reduced pressure. However, it is preferable to produce the polycarbonate by melt polymerization in one step or in two or more steps.

Examples of the above-mentioned basic catalyst include (1) ammonium hydroxides having an alkyl, aryl or aralkyl group (for example, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, trimethyl). Benzylammonium hydroxide, etc., tertiary amines (eg, trimethylamine, triethylamine, dimethylbenzylamine, triphenylamine, etc.), secondary amines, primary amines, tetramethylammonium borohydride, tetrabutylammonium borohydride, etc. Nitrogen-containing basic compounds, (2) hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, hydrogen carbonate Sodium, sodium carbonate, potassium carbonate, lithium carbonate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, lithium dihydrogen phosphate, potassium dihydrogen phosphite, sodium dihydrogen phosphite, disodium hydrogen phosphate, phosphorus Inorganic acid salts of alkali metals such as dipotassium hydrogen phosphate and dilithium hydrogen phosphate, sodium acetate, potassium acetate, lithium acetate, sodium stearate,
Organic acid salts of alkali metals such as sodium benzoate, hydrides of alkali metals such as sodium borohydride,
Alkali metal alcoholates such as sodium salt of phenol, (3) Alkaline earth metal hydroxides such as calcium hydroxide, barium hydroxide and magnesium hydroxide,
Inorganic acid salts of alkaline earth metals such as calcium hydrogen carbonate, barium hydrogen carbonate, magnesium hydrogen carbonate, calcium carbonate, barium carbonate and magnesium carbonate, alkaline earth metals such as calcium acetate, barium acetate, barium stearate and magnesium stearate. Examples of the organic acid salt include a single catalyst or a combination of plural catalysts.

In the production of polycarbonate, the basic catalyst is used in an amount of 10 _-8 to 10 _-1 mol, based on 1 mol of the aromatic dihydroxy compound used in the condensation polymerization reaction.
Particularly, it is preferably 10 ₋₇ to 10 ₋₂ mol.

The polycondensation reaction in the production of the polycarbonate can be carried out under the same conditions as the polycondensation reaction conditions in the conventionally known production methods of the polycarbonate. In particular, in the first step, the aromatic dihydroxy compound is used. Of polyphenyl carbonate with diphenyl carbonate at a temperature of 80 to 250 ° C., particularly 100 to 230 ° C., further 150 to 200 ° C., for 0.01 to 5 hours, particularly 0.01 to 4 hours, and further to 0. It is carried out for about 25 to 3 hours at around normal pressure or under reduced pressure, and then the second stage polycondensation reaction is carried out by further increasing the reaction temperature and the degree of reduced pressure from the first stage, and finally a reduced pressure of 1 mmHg or less. The temperature is preferably 240 to 320 ° C.

The polycondensation reaction may be carried out continuously or batchwise. Further, the reactor used in the polycondensation reaction is a tank reactor,
It may be a tubular reactor (particularly a self-cleaning reactor is preferable for the second-stage polycondensation) or a tower reactor. Then, next, the phenol compound by-produced in the above-mentioned polycondensation reaction is evaporated and separated, and the separated phenol compound is purified by a purification device (for example, an evaporation device, a distillation device, etc.), and a purified phenol compound is obtained. Can be obtained.

The high-purity diphenyl carbonate composition of the present invention comprises
The polycarbonate obtained by the polycondensation of the aromatic dihydroxy compound is excellent, and the polycarbonate obtained by the polycondensation has the same or higher molecular weight (10,000 to 40,000) as the polycarbonate obtained by the known melt polymerization method, and other polymers. A high level of physical properties can be achieved. Further, since the polycarbonate of the present invention is obtained as one having remarkably low coloring, it has a particularly high industrial utility value in applications requiring optical transparency such as compact discs and optical lenses.

[0074]

EXAMPLES Examples and comparative examples will be shown below. In the examples and comparative examples, composition analysis of each reaction solution and the like was performed by high performance liquid chromatography. In this analytical method, the measurement limit differs depending on the compound, but the measurement limit is about 0.
It is about 1 to 1 ppm.

[Example 1] [Manufacture of DPC-A] [Manufacture of diphenyl carbonate] A stirring tank made of glass lining and having an internal volume of 250 liters (two tank connection type, first tank to second tank connected by an overflow pipe) ) Is charged with diphenyl oxalate and tetraphenylphosphonium chloride (1.5% by weight based on diphenyl oxalate), and the jacket of the CO removal reactor is heated through a heating medium to remove the mixture under stirring. CO was reacted. When the conversion rate of the first reaction tank was about 60% and the conversion rate of the second tank was about 80%, diphenyl oxalate and tetraphenylphosphonium chloride (1.5% by weight based on diphenyl oxalate) were added. Continuous supply to the first reaction tank was started. In the above CO removal reaction, the temperature (reaction temperature) in the CO removal reactor was adjusted to 225 ° C. and maintained in each tank.

[Evaporation of de-CO reaction liquid] The de-CO reaction liquid extracted from the de-CO reaction device is supplied to a glass-lined evaporation tank (evaporator) having an internal volume of 100 liters, and the jacket of the evaporation device. 6kPaA through steam
The CO-free reaction solution was evaporated and concentrated while the diphenyl carbonate and the like were evaporated under reduced pressure to extract the evaporated components.

The evaporation components obtained by the evaporation of the CO-free reaction solution were as follows: diphenyl carbonate 88.54% by weight, diphenyl oxalate 9.71% by weight, and other impurities 1.75% by weight such as methylphenylphenyl carbonate. And about 50k
Obtained in g / h.

On the other hand, the purge amount is adjusted so that a part of the residual liquid (concentrated liquid) containing the phosphonium salt component derived from the CO-free catalyst has the composition of the residual liquid (concentrated liquid) as shown below. On the other hand, the reaction system was purged to the outside, and the rest was recycled to the above CO removal reactor to continuously perform the CO removal reaction. When the residual liquid (concentrated liquid) was recycled to the CO-free reactor, chloroform (amount corresponding to about 10 mol% with respect to the catalyst component in the concentrated liquid) was continuously added.

[First Distillation Purification (Recovery of Crude Fraction)] The above-mentioned evaporative components are cooled and liquefied and received in a liquid receiving tank, and from the liquid receiving tank, a column diameter of 100 A and a height of 7 m are filled. Tower (first
Distillation tower: Packing Melapack 500Y; Sumitomo Heavy Industries, Ltd., packing length 5 m, hereinafter also referred to as a low boiling column. ), The top (column top) of the tower is depressurized to 6 kPaA, low-boiling substances including phenol are removed from the top, and the residual liquid (bottom liquid) from which the low-boiling substances have been removed is bottom (column bottom). ). The composition of this residual liquid (can liquid) was 88.61% by weight of diphenyl carbonate, 9.71% by weight of diphenyl oxalate, and 1.67% by weight of other impurities, and was obtained at about 50 kg / hour.

Further, the residual liquid (the liquid in the first distillation column) was charged into a packed column having a column diameter of 250 A and a length of 8 m (second distillation column, packing:
Melapack 500Y, manufactured by Sumitomo Heavy Industries, Ltd., filling length 6 m, hereinafter also referred to as diphenyl oxalate recovery tower), the tower top (tower top) of the tower is set to a reduced pressure of 2.2 kPaA, and distillation is performed. While extracting the residual liquid (container liquid) containing diphenyl oxalate from the bottom of the column, a crude fraction of diphenyl carbonate having a purity of 99.9% by weight was extracted from the top of the column at a flow rate of about 43 kg / hour.

The above-mentioned crude distillate consisting of high concentration of diphenyl carbonate contains trace amount of diphenyl oxalate as 20 p
pm, 450 ppm of methylphenylphenyl carbonate, 150 ppm of phenyl parachlorobenzoate, and 2 ppm of light impurities such as benzofuran-2,3-dione.

On the other hand, the above-mentioned residual liquid (can liquid of the second distillation column)
Is diphenyl carbonate 46.74% by weight, diphenyl oxalate 48.46% by weight, other impurities 4.63% by weight
And was withdrawn from the bottom of the column of the second distillation column at a flow rate of about 7 kg / hour.

[Removal of Light Impurities from Crude Fraction (Distillation-Removal Method)] The above crude fraction was converted into a packed column having a column diameter of 200 A and a length of 8 m (light impurity removal column, packing: Melapak 500Y,
Sumitomo Heavy Industries, Ltd., filling length 5 m, hereinafter also referred to as decolorization tower. ), The top 1.6 kPaA of this tower,
Continuously distilling at a reflux ratio of 20, from the top of the tower,
An impurity fraction consisting of a relatively high concentration of diphenyl carbonate containing light impurities at a content of about 0.02% by weight was withdrawn at a flow rate of 0.4 kg / hr, while the light impurities removal tower was described above. From the bottom, the content of light impurities is 0.
A colorless and transparent residual liquid consisting of a high concentration of diphenyl carbonate of 2 ppm or less was extracted at a flow rate of about 43 kg / hour.

[Second Distillation Purification] The above-mentioned residual liquid (the liquid for removing the light impurities in the tower) was converted into a column having a diameter of 250 A and a length of 10 m (DP
C refining tower, packing: Melapak 500Y, manufactured by Sumitomo Heavy Industries Ltd., packing length 8 m), and continuously distilled and purified at a reflux ratio of 3 at a reduced pressure of 1.6 kPaA at the top of the tower (column top). From the top of the tower (the top of the tower), the DPC fraction consisting of diphenyl carbonate having a purity of 99.95% by weight or more (product high-purity diphenyl carbonate: DPC-
A) was obtained at about 42 kg / h. The DPC fraction has a methylphenylphenyl carbonate content of 150 ppm, a phenyl benzoate content of 30 ppm, and a phenol content of 10 ppm, benzofuran-
The content of 2,3-dione was 0.2 ppm or less, and Hazen 5 or less was colorless and transparent.

[Example 2] [Production of DPC-B] In the second distillation purification, the purity was 99 in the same manner as in Example 1 except that the column packing height was changed to 12 m and the reflux ratio was changed to 10. DPC fraction containing more than 95% by weight of diphenyl carbonate (high-purity diphenyl carbonate: D
PC-B) was obtained at about 42 kg / h. This DPC fraction (DPC-B) had a methylphenylphenyl carbonate content of 30 ppm and a phenyl benzoate content of 50 p.
pm, the content of phenol is 10 ppm and the content of benzofuran-2,3-dione is 0.2 pp
m or less and Hazen 5 or less and colorless and transparent.

[Example 3] [Polycarbonate: PC-
Production Method of A] Using the DPC fraction (DPC-A) of high-purity diphenyl carbonate obtained in Example 1, a polycarbonate was produced as follows.

The DPC fraction used (DPC-A)
The content of each impurity component in the product was 150 ppm for methylphenylphenyl carbonate and 3 for phenyl benzoate.
0 ppm, benzofuran-2,3-dione 0.2 ppm
It was below.

400 parts by weight of bisphenol A, 700 parts by weight of toluene and 28 parts by weight of ethanol (volume ratio of 2
2: 1) recrystallized from bisphenol A
I got a purified product.

Made of stainless steel (SUS316L)
The purified bisphenol A is added to the polymerization reaction vessel of
22.83 parts by weight, said high concentration of diphenyl carbonate
(DPC fraction) 22.71 parts by weight and vinyl as a catalyst
Sodium hydroxide 2 x 1 per mol of Sphenol A
0_-6Moles and tetraammonium hydroxide 1 x 10
_-FourMoles and vacuum degas at room temperature for 0.5 hours
Then, heat the polymerization reactor to carry out the polycondensation reaction.
Distillation of phenol begins at 230 ° C and 100 torr
1 hour, then 240 ° C., 100 Torr.
5 hours, then 100 Torr at 255 ° C for 10 minutes,
And reduce the pressure from 100 to 50 Torr in 15 minutes
Hold for 15 minutes to allow polycondensation reaction,
From 50 Torr at 270 ° C to 1 Torr in 30 minutes
Decompress and maintain at 270 ° C and 1 Torr for 1 hour to reduce degeneracy
After reaction, polycarbonate (PC-A) 25.3
5 parts by weight (yield 100%) was obtained. The obtained polycarbonate
Nate (PC-A) has an average molecular weight of 15,000 and a hue.
(Col b value) was 0.6.

The average molecular weight was 0.7 g / sample polymer.
The viscosity of a dl methylene chloride solution was measured using an Ubbelohde viscometer, and the viscosity average molecular weight was determined using the formula: [η] = 1.23 × 10 ₋₄ M _0.83 . Color tone (hue b value) is La of polycarbonate beret (minor axis x major axis x length = 2.5 mm x 3.3 mm x 3.0 mm).
The b value was measured using a color tone measuring device [ND- manufactured by Nippon Denshoku Industries Co., Ltd.].
1001 DP] and the degree of coloring (yellow) measured by the reflection method.
B value was used as the degree of.

[Example 4] [Polycarbonate: PC-
Production Method of B] A polycarbonate (PC) was produced in substantially the same manner as in Example 3 except that the DPC fraction (DPC-B) containing the high-purity diphenyl carbonate obtained in Example 2 was used.
-B) 25.35 parts by weight (yield 100%) was obtained. The obtained polycarbonate (PC-B) was measured in the same manner as in Example 3 and found to have an average molecular weight of 15,000 and a hue (co
value of 0.6).

[Comparative Example 1] [Polycarbonate: PC-
Production Method of C] Methylphenylphenyl carbonate (MPPC) was added to the DPC fraction (DPC-A) obtained in Example 1 to give MPPC.
High-purity diphenyl carbonate (D
PC-C) was prepared and its DPC-C was used, except that polycarbonate (PC-C) was used in the same manner as in Example 1.
C) 25.35 parts by weight (yield 100%) was obtained. The obtained polycarbonate (PC-B) was measured in the same manner as in Example 3 and found to have an average molecular weight of 14,000 and a hue (col).
b value) was 1.1.

[0093]

Industrial Applicability The high-purity diphenyl carbonate composition of the present invention is a product in which methylphenylphenyl carbonate (MPPC) is considerably reduced and which is composed of high-purity diphenyl carbonate. The product can be industrially easily and reproducibly obtained by utilizing a method in which evaporation from the deCO reaction liquid of diphenyl oxalate and distillation purification operation are combined. Since the high-purity diphenyl carbonate composition of the present invention has a high concentration and reduces MPPC as an impurity to an unaffected amount, it can be stably used as it is in a polycondensation reaction as a monomer raw material in the production of polycarbonate. It is possible to reproducibly produce a polycarbonate of the desired quality.

[Brief description of drawings]

FIG. 1 is a flow diagram illustrating an outline of a method for obtaining high-purity diphenyl carbonate according to the present invention.

FIG. 2 is a method for obtaining high-purity diphenyl carbonate according to the present invention, in which light impurities are removed by a distillation operation of a crude fraction (distillation-
FIG. 6 is a process diagram showing an example of a case of performing the removal method).

[Explanation of symbols]

1 catalyst supply line 2 Diphenyl oxalate (DPO) supply line 3 De-CO reactor (reactor) 4 Reaction liquid line 5 evaporator 6 Concentrated liquid line 7 Purge liquid line 8 CO emission line 9 Evaporative component line 11 First distillation tower 13 Light impurity removal tower 14 DPC purification tower 16 DPC fraction (product) line

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shuji Tanaka             10 Ube at 1978 Kogushi, Ube City, Yamaguchi Prefecture             Kosan Co., Ltd.Ube Chemical Factory (72) Inventor Yutaka Asada             10 Ube at 1978 Kogushi, Ube City, Yamaguchi Prefecture             Kosan Co., Ltd.Ube Chemical Factory F-term (reference) 4H006 AA02 AD13 BA53 BD40 BD60                       BJ50 BT40                 4H039 CA66 CG30                 4J029 AA09 AB04 AD01 AE01 BB12A                       BB12C BF14A BF14B BH02                       DB07 DB11 DB13 HC05A                       JA121 JC021 JC091 JC731                       JF031

Claims (14)

[Claims] 1. A high-purity diphenyl carbonate composition containing methylphenylphenyl carbonate, wherein the content of methylphenylphenyl carbonate is 300 ppm by weight or less, and the total content of impurities including methylphenylphenyl carbonate is 1. A high-purity diphenyl carbonate composition, which is less than or equal to wt% and the balance is diphenyl carbonate. 2. The high-purity diphenyl carbonate composition according to claim 1, wherein the content of methylphenylphenyl carbonate is 1 to 300 ppm by weight. 3. The content of methylphenylphenyl carbonate is 200 ppm by weight or less, the total content of impurities including methylphenylphenyl carbonate is 0.5% by weight or less, and the balance is diphenyl carbonate. The high-purity diphenyl carbonate composition described in 1. 4. The high-purity diphenyl carbonate composition according to claim 3, wherein the content of methylphenylphenyl carbonate is 10 to 200 ppm by weight. 5. Benzofuran-2,3-in the impurities
The high-purity diphenyl carbonate composition according to any one of claims 1 to 4, comprising dione, and the content thereof is 1 ppm by weight or less based on the diphenyl carbonate composition. 6. The phenyl benzoate is contained in the impurities, and the content thereof is 100 with respect to the diphenyl carbonate composition.
The high-purity diphenyl carbonate composition according to any one of claims 1 to 5, which has a weight ppm or less. 7. The high-purity diphenyl carbonate composition according to any one of claims 1 to 6, which is obtained by purifying a reaction product of a CO removal reaction of diphenyl oxalate. 8. A low-boiling point impurity and a high-boiling point impurity are removed by distilling a crude diphenyl carbonate composition containing impurities containing methylphenylphenyl carbonate to obtain a crude fraction containing a high concentration of diphenyl carbonate. After obtaining the crude fraction, light impurities are further removed by distillation, and then the residue is distilled to remove methylphenylphenyl carbonate from the residue. The method for obtaining the high-purity diphenyl carbonate composition according to any one of items. 9. A reaction obtained by subjecting the crude diphenyl carbonate composition to a CO deoxidation reaction of a crude diphenyl oxalate raw material derived from phenol mixed with cresol in the presence of a CO deoxidizing catalyst containing an organic phosphorus compound. The method for obtaining a high-purity diphenyl carbonate composition according to claim 8, which is obtained by evaporating the product. 10. The crude fraction is 50 to 5000 weight p.
The method for obtaining a high-purity diphenyl carbonate composition according to claim 8, characterized in that it contains methylphenylphenyl carbonate in an amount in the range of pm, and the diphenyl carbonate content is 95.0% by weight or more. . 11. The residual content is 50 to 2500 weight p.
The method for obtaining a high-purity diphenyl carbonate composition according to claim 8, characterized in that it contains methylphenylphenyl carbonate in an amount in the range of pm, and the content of diphenyl carbonate is 98.0% by weight or more. . 12. The method for obtaining a high-purity diphenyl carbonate composition according to claim 8, wherein the light impurities removed from the crude fraction by distillation have benzofuran-2,3-dione as a main component. . 13. A polycondensation reaction of the high-purity diphenyl carbonate composition according to any one of claims 1 to 7 and an aromatic dihydroxy compound in the presence of a transesterification catalyst. Polycarbonate manufacturing method. 14. A polycarbonate having an average molecular weight of 14,000 or more and a yellow coloring degree of 0.9 or less as a b value, which is obtained by the production method according to claim 13.