JP3435826B2 - Method for producing aromatic polycarbonate - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an aromatic polycarbonate. More specifically, it relates to a method for producing a polycarbonate having no color by reacting a pure diphenyl carbonate produced from a dialkyl carbonate by a transesterification reaction with an aromatic dihydroxy compound.

[0002]

2. Description of the Related Art Aromatic polycarbonates are widely used in many fields as engineering plastics having excellent heat resistance, impact resistance, transparency and the like. Various studies have been conducted on the method for producing the aromatic polycarbonate, and among them, aromatic dihydroxy compounds such as 2,2-bis (4-hydroxyphenyl) have been studied.
The interfacial polymerization method in which propane (hereinafter referred to as bisphenol A) and phosgene are reacted is common.

However, in this interfacial polymerization method using phosgene, toxic phosgene must be used, a large amount of solvent is used, and a large amount of alkali is required to neutralize by-produced hydrogen chloride. However, there is a problem that the device may be corroded by a chlorine-containing compound such as sodium chloride.

On the other hand, as a method for producing an aromatic polycarbonate from an aromatic dihydroxy compound and diphenyl carbonate, for example, a melt polymerization method in which bisphenol A and diphenyl carbonate are transesterified in a molten state has been known. By using this method, the above-mentioned problems can be solved, but this method has a problem that the aromatic polycarbonate produced is colored unless the monomer diphenyl carbonate is sufficiently purified.

When diphenyl carbonate is produced by a phosgene method, that is, a method in which phenol and phosgene are reacted in the presence of a basic compound, a purification method such as washing the product diphenyl carbonate with warm water is known (Shogane). Mikio et al., Polycarbonate Resin Course, 1969, Nikkan Kogyo Shimbun, pages 62 and 6.
Page 4). It is also known that a transparent, colorless polycarbonate is obtained when an aromatic polycarbonate is produced by a melt polymerization method using purified diphenyl carbonate (JP-B-38-1373,
Japanese Patent Publication No. 42-9820). However, although this melt polymerization method does not use phosgene in the polymerization process, since phosgene is used in the monomer production process as described above, if the corrosion of the equipment due to the chlorine-containing compound or the purification of the monomer is insufficient, the final product There is a problem of polymer coloring.

As a method for solving this, it has been proposed to use diphenyl carbonate synthesized by a method of transesterifying a dialkyl carbonate in the presence of phenol. However, even in this method, the problem of coloring has not yet been sufficiently solved.

Therefore, for example, Japanese Patent Application Laid-Open No. 61-172852.
In the gazette, it is proposed to improve the catalyst to reduce impurities in diphenyl carbonate, but as can be seen from the description in the gazette, the impurities are still 10%.
It exists at about 00 ppm, and it is hard to say that it is sufficient.

Another method is disclosed in Japanese Patent Laid-Open No. 4-1008.
No. 24 publication does not use a polymerization catalyst and has a chlorine content of 0.
05ppm or less and the xanthone content is 10
A method using a diaryl carbonate that is below ppm is described. However, in this method, a catalyst is not used during the polymerization, and there is another problem that the reaction rate is remarkably reduced in the case of the polymerization, which is not practical as an industrial method.

Further, JP-A-6-179744 discloses that phenyl salicylate, o-phenoxybenzoic acid and o-
The use of carbonic acid diesters that are substantially free of phenyl phenoxybenzoate is described. However, according to the study by the present inventors, these compounds were not detected in commercially available diphenyl carbonate produced from dimethyl carbonate. However, when the polymerization is carried out as it is using commercially available diphenyl carbonate, the polycarbonate produced is considerably colored. From this, it is presumed that the cause of coloring is due to other substances. As described above, a method for producing a colorless aromatic polycarbonate using diphenyl carbonate produced from dialkyl carbonate has not been established yet.

[0010]

DISCLOSURE OF THE INVENTION The present invention is a transesterification method (melt polymerization method) using diphenyl carbonate.
It is an object of the present invention to provide a method for efficiently producing an uncolored aromatic polycarbonate at a practical reaction rate.

[0011]

Means for Solving the Problems As a result of intensive investigations by the present inventors in order to solve the above problems,
In diphenyl carbonate produced from a dialkyl carbonate, in addition to xanthone which is pointed out in JP-A-4-100824, about 1100 ppm o
-It was found that phenyl methoxybenzoate was included as an impurity. Further, when diphenyl carbonate from which the impurities are removed is used, a polycarbonate which is hardly colored even by polycondensation reaction in the presence of a catalyst can be produced, and phenyl o-methoxybenzoate causes coloring. Therefore, the present invention has been completed.

That is, the present invention is characterized in that phenyl o-methoxybenzoate and diphenyl carbonate substantially free of xanthone are used as raw materials when an aromatic polycarbonate is produced by reacting diphenyl carbonate with an aromatic dihydroxy compound. Is a method for producing an aromatic polycarbonate.

It is also known that chlorine and iron cause the coloring of polycarbonate. In order to produce a polycarbonate having an excellent color tone, it is preferable to use a raw material that does not substantially contain these impurities. But,
In the present invention, when the starting material to be used contains chlorine or iron at a high concentration, it is used after being purified by a method such as washing, distillation and recrystallization in advance.

The above-mentioned chlorine means hydrolyzable chlorine, and does not include chlorine which is bonded to a carbon atom by a covalent bond and does not decompose under ordinary hydrolysis conditions. Examples of hydrolyzable chlorine include chlorine present as an acid such as hydrochloric acid or a salt such as sodium chloride and potassium chloride, or organic hydrolyzable chlorine such as phenyl chloroformate. Further, iron means all forms of iron contained, and means metallic iron, divalent iron ions and iron compounds, and trivalent iron ions and iron compounds.

The method for producing the diphenyl carbonate used in the present invention is not particularly limited. For example, a method of transesterifying a dialkyl carbonate and phenol in the presence of a known catalyst, or a method after synthesizing an alkylphenyl carbonate is used. It is synthesized by a known catalyst disproportionation method. In the diphenyl carbonate thus obtained, 110
It contains about 0 ppm of phenyl o-methoxybenzoate and about 40 ppm of xanthone. When diphenyl carbonate containing such impurities is directly used as a raw material, the polycarbonate produced as described above is colored.

In the present invention, in order to obtain a colorless polycarbonate, the content of phenyl o-methoxybenzoate in diphenyl carbonate is 50 pp / w.
It is desirable that it is not more than m and does not substantially contain.
Such diphenyl carbonate can be obtained by purifying the diphenyl carbonate produced above by washing, distillation or recrystallization, or a combination of these methods. If necessary, these purifications may be performed multiple times. In this purification step, xanthone contained as an impurity in diphenyl carbonate is also removed at the same time, and xanthone is substantially not contained.

The above-mentioned purification method will be specifically described below. (1) Washing can be performed by bringing a solvent in which diphenyl carbonate is not substantially dissolved, or in which it is slightly dissolved, into sufficient contact with diphenyl carbonate by means of stirring and mixing. This operation can be carried out at a temperature near room temperature while the diphenyl carbonate remains solid, but it can be carried out more efficiently if carried out at a temperature above the melting point of diphenyl carbonate. (2) Distillation can use a usual method. That is, diphenyl carbonate is purified by distillation using a multi-stage or single-stage distillation column under a pressure of 760 to 0.1 mmHg. Regarding the distillation temperature, the kettle temperature is preferably 250 ° C. or lower in order to avoid decomposition of diphenyl carbonate. (3) For recrystallization, a usual method can be used. That is, a solvent having a low solubility of diphenyl carbonate near room temperature and a high solubility at high temperature is used to once dissolve the diphenyl carbonate at a high temperature. The solution is cooled to around room temperature to precipitate diphenyl carbonate, separated from the solvent and purified. The high temperature is lower than the boiling point of the solvent used and may be any temperature as long as it is room temperature or higher, but when a solvent having a boiling point higher than the melting point of diphenyl carbonate is used, It is preferred to operate at temperatures below the melting point. Suitable solvents that can be used include heptane, toluene, isopropanol and the like.

As the catalyst for the transesterification reaction or disproportionation reaction in the above-mentioned diphenyl carbonate production process, known catalysts can be used. Examples of these compounds include the compounds described in the above-mentioned JP-A-4-100824, that is, lead compounds, copper compounds, alkali metal complexes, zinc complexes, cadmium complexes, iron group metal compounds,
Examples thereof include zirconium complexes, Lewis acid compounds, organic tin compounds, solid acid catalysts and the like.

The aromatic polycarbonate in the present invention can be produced by melt-polycondensing the diphenyl carbonate purified as described above and an aromatic dihydroxy compound by a known method.

Next, the method for producing the aromatic polycarbonate in the present invention will be specifically described below. The aromatic dihydroxy compound used in the present invention may be any divalent phenol. Specifically, bis (4-hydroxyphenyl) methane, 1,
1-bis (4-hydroxyphenyl) ethane, 2,2-
Bis (4-hydroxyphenyl) propane [bisphenol A], 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (4-hydroxy-3,5-diethylphenyl) propane , 2,2-
Bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane ,
1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 4,4′-dihydroxydiphenyl ether,
4,4'-dihydroxy-3,3'-dimethyldiphenyl ether, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide, 4,4'-dihydroxydiphenyl sulfoxide, 4 , 4'-dihydroxy-3,3'-
Dimethyldiphenyl sulfoxide, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxy-
3,3'-dimethyldiphenyl sulfone and the like can be mentioned. Of these, 2,2-bis (4
-Hydroxyphenyl) propane is preferably used. Further, these aromatic dihydroxy compounds can be used alone or in combination.

In the present invention, when producing an aromatic polycarbonate, a polyfunctional compound having three or more functional groups in one molecule may be used together with the above aromatic dihydroxy compound and diphenyl carbonate. it can. The polyfunctional compound is used usually in the range of 0.01 to 3 mol%, preferably 0.05 to 1 mol% based on 1 mol of the aromatic dihydroxy compound.

As such a polyfunctional compound, a compound having a phenolic hydroxyl group or a carboxyl group is preferable, and a compound containing three phenolic hydroxyl groups is particularly preferable. Specifically, phloroglucin, 2,6-
Dimethyl-2,4,6-tri (4-hydroxyphenyl) -3-heptene, 4,6-dimethyl-2,4,6-
Tri (4-hydroxyphenyl) -2-heptene, 1,
3,5-tri (4-hydroxyphenyl) benzene,
1,1,1-tri (4-hydroxyphenyl) ethane,
2,6-bis (2-hydroxy-5-methylbenzyl)
-4-methylphenol, trimellitic acid, 1,3,5
-Benzenetricarboxylic acid, pyromellitic acid and the like.

In the present invention, examples of the catalyst used when the aromatic polycarbonate is produced by the transesterification reaction include alkali metal compounds, alkaline earth metal compounds, quaternary phosphonium salts and quaternary ammonium salts. used.

Specific examples of the alkali metal compound include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, sodium acetate, Potassium acetate, lithium acetate, sodium stearate, potassium stearate, lithium stearate, sodium borohydride, lithium borohydride, sodium phenyl borohydride, sodium benzoate, potassium benzoate, lithium benzoate, disodium hydrogen phosphate , 2 potassium hydrogen phosphate, 2 lithium hydrogen phosphate, 2 sodium phenyl phosphate, 2 potassium phenyl phosphate, 2 lithium phenyl phosphate, 2 sodium salt of bisphenol A, 2 potassium salt, 2 lithium salt, of phenol Thorium, potassium, lithium salt or the like is used.

As the alkaline earth metal compound,
Specifically, calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium hydrogen carbonate, barium hydrogen carbonate, magnesium hydrogen carbonate, strontium hydrogen carbonate, calcium carbonate, barium carbonate, magnesium carbonate, strontium carbonate, acetic acid. Calcium, barium acetate, magnesium acetate, strontium acetate, calcium stearate, barium stearate, magnesium stearate, strontium stearate and the like are used.

Specific examples of the quaternary phosphonium compound include, for example, tetraphenylphosphonium tetraphenylborate, benzyltriphenylphosphonium tetraphenylborate, methyltriphenylphosphonium tetraphenylborate, ethyltriphenylphosphonium tetraphenylborate and butyltriphenyl. Phosphonium tetraphenylborate is preferably used.

As the quaternary ammonium salt, tetramethylammonium hydroxide, tetraethylammonium hydroxide, trimethylphenylammonium hydroxide, triethylphenylammonium hydroxide, trimethylbenzylammonium hydroxide,
Triethylbenzylammonium hydroxide, tributylbenzylammonium hydroxide, dimethylbenzylphenylammonium hydroxide, tribenzylmethylammonium hydroxide, tribenzylphenylammonium hydroxide, tetrabenzylammonium hydroxide, trimethylcyclohexylammonium hydroxide, tetramethylammonium chloride, Tetraethylammonium chloride, trimethylphenylammonium chloride, triethylphenylammonium chloride, trimethylbenzylammonium chloride, triethylbenzylammonium chloride, dimethylbenzylphenylammonium chloride, tributylbenzylammonium chloride, tetrabenzylan Chloride, trimethyl cyclohexyl ammonium chloride, tri-benzyl phenyl ammonium chloride, tetramethyl ammonium bromide, tetraethyl ammonium bromide,
Trimethylphenylammonium bromide, trimethylbenzylammonium bromide, triethylbenzylammonium bromide, tributylbenzylammonium bromide, tribenzylmethylammonium bromide, tetrabenzylammonium bromide, trimethylcyclohexylammonium bromide, tribenzylphenylammonium bromide, tetraethylammonium iodide, triethylbenzylammonium Examples include iodide and trimethylphenylammonium iodide.

These catalysts may be used alone or in admixture of two or more. The amount of catalyst is 1 × 10 ^-9 per 1 mol of the aromatic dihydroxy compound used as a raw material.
To 1 × 10 ⁻³ mol, preferably 1 × 10 ⁻⁷ to 1 ×
Used in an amount of 10 ^-5 mol.

In the transesterification reaction in the present invention, the above raw materials are melted and melt-polycondensed while removing by-products under atmospheric pressure or reduced pressure. This reaction can be carried out in one step, but may be carried out in a multi-step process of two or more steps. Specifically, the reaction is carried out at a temperature of 120 to 240 ° C. for 0 to 5 hours under normal pressure. Then, the reaction temperature is raised while raising the degree of vacuum of the reaction system to carry out the reaction, and finally the polycondensation reaction is carried out at a temperature of 240 to 320 ° C. under a reduced pressure of 1 mmHg or less.

The reaction between the aromatic dihydroxy compound and diphenyl carbonate as described above may be carried out continuously or batchwise. Further, the reaction apparatus used for carrying out the above reaction may be of a tank type, a tube type, or a column type.

Further, in the present invention, the obtained polymer is added to a catalyst neutralizing agent, a heat stabilizer, a pigment, a dye, a reinforcing agent or a filler, an ultraviolet absorber, a lubricant, a releasing agent, a crystal nucleating agent, a plasticizer. ,
A fluidity improver, an antistatic agent, etc. can be added. These additives are typically added to the molten polymer directly after the completion of polymerization or in the form of a masterbatch, or once pelletized, each component and the pellet are represented by a turnbull mixer, a Henschel mixer, a ribbon blender, or a super mixer. Each component can be mixed with the aromatic polycarbonate resin by a method in which the components are dispersed and mixed with a high-speed mixer as described above, and then melt-kneaded with an extruder, a Banbury mixer, a roll or the like.

[0032]

EXAMPLES The method of the present invention will be explained by the following examples, but the present invention is not limited to these examples. For the detection of phenyl o-methoxybenzoate and xanthone, a liquid chromatograph (detector: UV-VIS detector SPD-10A manufactured by Shimadzu Corporation, wavelength 2) was used.
54 nm; detection limit: phenyl o-methoxybenzoate (1.0 ppm, xanthone 0.1 ppm) was used.

Example 1 100 g of a commercially available diphenyl carbonate produced from dimethyl carbonate was added to 200 g of isopropanol, heated to 70 ° C. to dissolve it, and then filtered while hot. The filtrate was left standing to cool for 12 hours, the crystallized crystals were filtered off, and the diphenyl carbonate remaining on the filter paper was further washed with 100 g of room temperature isopropanol. For washing, half the amount of isopropanol used for recrystallization was used. This was air dried for 24 hours and then vacuum dried at 40 ° C. for 1 hour to obtain purified diphenyl carbonate. (The yield is 87.
2 g) The impurity concentration in this purified diphenyl carbonate is shown in Table 1.

In a 200 ml glass reactor equipped with a stirrer, 21.93 g (0.1024 mol) of the purified diphenyl carbonate obtained above, 22.83 g (0.1 mol) of bisphenol A, and disodium phenyl phosphate as a catalyst. 16.35 μg (7.5 x 1
^0-8 mol) was introduced into the reactor. The catalyst is 50μ
1 as an aqueous solution.

After purging the reactor with nitrogen, 1.
The mixture was heated and melted for 5 hours, and subsequently heated to 267 ° C. at a heating rate of 25 ° C. per hour while stirring. At the same time, the pressure was reduced from normal pressure to 1 mmHg over 5 hours, and the state of 1 mmHg or less was further maintained for 1 hour.

As a result of the above polymerization reaction, a transparent aromatic polycarbonate was obtained. This polycarbonate has Mv (viscosity average molecular weight) = 20700; APHA = 0 to 10, Y
The I value was 0.31 [concentration: 4 g / 25 ml, solvent: dichloromethane].

Comparative Example 1 The same as Example 1 except that a commercially available diphenyl carbonate produced from dimethyl carbonate (impurity concentration contained therein is shown in Table 1) was used as a raw material without purification. Polymerization was carried out by the method.

The aromatic polycarbonate obtained as a result of the polymerization reaction was colored yellow. This polycarbonate had Mv = 15900; APHA = 15-20 and a YI value of 1.16.

Example 2 Example 1 except that 100 g of a commercially available diphenyl carbonate produced from dimethyl carbonate was recrystallized from 100 g of isopropanol (the impurity concentration contained in this is shown in Table 1) was used as a raw material. Polymerization was carried out in the same manner as in 1.

As a result of the polymerization reaction, a transparent aromatic polycarbonate was obtained. This polycarbonate has Mv = 2
0400; APHA = 0 to 10, YI value was 0.38.

Comparative Example 2 Example 1 except that 100 g of commercially available diphenyl carbonate produced from dimethyl carbonate was recrystallized from 75 g of isopropanol (impurity concentration contained in this is shown in Table 1) was used as a raw material. Polymerization was carried out in the same manner as in 1.

The aromatic polycarbonate obtained as a result of the polymerization reaction was colored yellow. This polycarbonate had Mv = 19800; APHA = 10 to 15 and YI value of 0.56.

Example 3 In Example 1, 6.0 μg (1.5 × 10 ⁻⁷ mo) of sodium hydroxide was used instead of disodium phenylphosphate.
Polymerization was carried out in the same manner as in Example 1 except that l) was used. As a result, a transparent polycarbonate was obtained as in Example 1, with an APHA value of 0 to 10 and a YI value of 0.35.
Met. Moreover, Mv was 16500.

The above results are summarized in Table 1.

[0045]

Industrial Applicability By using the diphenyl carbonate produced by the method of the present invention as a raw material, a polycarbonate having an excellent color tone can be easily obtained and its industrial effect is great.

[Table 1] * Concentration is ppm. PMB represents phenyl o-methoxybenzoate.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-179744 (JP, A) JP-A-4-100824 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 64/00-64/42

Claims (2)

(57) [Claims] 1. A fragrance characterized by using phenyl o-methoxybenzoate and diphenyl carbonate substantially free of xanthone as a raw material in the production of an aromatic polycarbonate by reacting diphenyl carbonate with an aromatic dihydroxy compound. Group Polycarbonate Production Method 2. A diphenyl carbonate having a phenyl o-methoxybenzoate content of 50 ppm or less and containing substantially no xanthone as a raw material.
Method of description