JPH10226724A - Polycarbonate resin reduced in volatile chlorine and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polycarbonate resin being excellent in heat stability when molten, undergoing little change in hue after being melt-molded, reduced in chlorine volatilized during ordinary temperature storage and less corrosive to electric and electronic components and to provide a process for producing the same. SOLUTION: This invention provides a low-volatile-chlorine-content polycarbonate resin which forms at most 30ppb when heated at 280 deg.C for 30min and stored for 3 days at room temperature and a process for producing a carbonate- bond-containing resin by using phosgene as the starting material, wherein the phosgene used is one having a chlorine content of 1,000ppb or below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polycarbonate resin containing less volatile chlorine and a method for producing the same. More specifically, the present invention relates to a stable polycarbonate resin of low quality of volatile chlorine when kept at room temperature and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, a two-phase interfacial polycondensation method for obtaining a polycarbonate in the presence of an organic solvent by the reaction of an aqueous solution of an alkali metal salt of a diphenol such as bisphenol A with phosgene, In the melt polycondensation method for obtaining a polycarbonate, a number of impurities in phosgene used as a raw material have been studied. Among them, the amount of chlorine contained in phosgene is several hundred ppm.
Technology to reduce the order of tens to tens of ppm was introduced,
It has been proposed that such a technique for reducing the amount of chlorine is good for polycarbonate. For example, US Pat.
No. 0253 and U.S. Pat. No. 3,331,873 disclose a method of adsorbing and removing chlorine contained as an impurity by passing phenols or activated carbon after phosgene production. However, only a technique for simply reducing the amount of chlorine contained in phosgene from the order of several hundred ppm to several tens ppm is introduced.Specifically, phosgene with a reduced chlorine amount is used as polycarbonate. It does not disclose use as a raw material for production. Further, there is no teaching at all regarding the fact that chlorine volatilized at room temperature after molding of the polycarbonate resin has a causal relationship with chlorine contained in the raw material phosgene.

On the other hand, JP-A-62-297320 and JP-A-62-297321 contain carbon tetrachloride having a higher boiling point than phosgene as an impurity in phosgene which is a raw material of a resin having a carbonate bond. In order to generate hydrogen chloride by heating at the time of molding such a resin produced using phosgene as a raw material, the content of carbon tetrachloride in phosgene may be set to a certain amount or less. It has been reported. In this case, it discusses the hydrogen chloride that is decomposed and generated while being heated during molding, and teaches nothing about the phenomenon that chlorine gradually evaporates while being left at room temperature after molding. Absent.

[0004] Further, phosgene is generally produced by reacting carbon monoxide with chlorine using activated carbon as a catalyst. Since this reaction reaches an equilibrium state in the final stage, an attempt to reduce the chlorine content in phosgene will shift the CO / Cl ₂ ratio in the direction of excess CO. However, a large excess of CO results in a loss of CO gas, and at the same time, an increase in the amount of phosgene discharged as off-gas accompanying the CO gas, resulting in an extremely low unit consumption. Therefore, in most phosgene plants, it is usual to operate with an excessive amount of CO suppressed to the limit where phosgene loss can be suppressed. As a result,
The very small amount of chlorine has been neglected because the measuring means and the measuring accuracy were insufficient.

[0005]

The inventors of the present invention have conducted intensive studies on volatile chlorine at room temperature from molded articles of polycarbonate obtained as a final product. It has been found that there is a relationship between chlorine contained as an impurity in phosgene used as a raw material for production. That is, chlorine remaining as an impurity in phosgene is chlorinated in a specific part of the raw material in an initial reaction stage in the polycarbonate production process in some form, remains unchanged until the final process, and is left at room temperature after molding. During this time, it was found that chlorine gradually evaporated (detection was recognized as Cl ions). On the other hand, when carbon tetrachloride as described above remains in the polycarbonate or when the chloroformate group generated in the polycarbonate production process by the two-phase interfacial polycondensation method remains, the resin is melt-molded. Occurrence of hydrogen chloride is sometimes observed. However, these should be clearly distinguished from the chlorine which evaporates after the above-mentioned molding. That is, in the case of a Cl group having a very high reactivity, it is immediately converted to hydrogen chloride by the heat during melt molding, but in the case of the above-mentioned chlorinated portion, rather than coming off in the melt molding, rather than being removed at room temperature after molding. It was found that chlorine was gradually generated below by photolysis or the like. Therefore, if carbon tetrachloride remains in the polycarbonate or the chloroformate group generated during the polycarbonate production process by the two-phase interfacial polycondensation method remains, the molded article is melt-molded. Once removed by washing with pure water.

On the other hand, in the case of the site chlorinated by the chlorine remaining in the phosgene, chlorine is temporarily generated by applying heat to the polycarbonate during melt molding. However, it was still not completely removed, and it was found that it was gradually generated when left at room temperature (detection was recognized as Cl ions). Such chlorine is called "volatile chlorine". Although the existence of such volatile chlorine has been often ignored until now, it has been found that it becomes a problem with the recent improvement in quality and physical properties of various polycarbonate resin molded products. An object of the present invention is to provide a polycarbonate resin having a small amount of volatile chlorine and a method for producing the same.

[0007]

SUMMARY OF THE INVENTION The present inventors have found that the more the chlorine contained as an impurity in phosgene is removed to the extent possible, the more the chlorine is volatilized when left at room temperature after molding. Knowing that the amount of chlorine coming down is small, the present invention has been completed. As described in US Pat. No. 3,230,253 and US Pat. No. 3,331,873, molecular chlorine contained in phosgene is usually 330 n.
It is detected by absorbance at m wavelength, and the lower limit of detection is 10p
pm, and in fact, there is no accurate analytical means for chlorine content of 10 ppm or less. In this regard, the present inventors have collected a large amount (70 g or more) of COCl ₂ containing a trace amount of chlorine as an impurity, and when this is absorbed into an aqueous sodium hydroxide solution, only chlorine changes to NaClO. It was found that a trace amount of chlorine can be measured by redox titration.
That is, the polycarbonate resin having a low volatile chlorine of the present invention is characterized in that the amount of chlorine generated by heating at 280 ° C. for 30 minutes and holding at room temperature for 3 days is 30 ppb or less. . Further, another method of the present invention for producing a polycarbonate resin having a low volatile chlorine is a method for producing a resin having a carbonate bond using phosgene as a raw material, wherein the phosgene having a chlorine concentration of 1,000 ppb or less is used as a raw material phosgene. Is used.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION

[I] Production of Polycarbonate Resin with Low Volatile Chlorine (1) Overview The method for producing a carbonate resin with low volatile chlorine of the present invention can be carried out by a method equivalent to a known method for producing a resin having a carbonate bond. There is no particular limitation, and various production methods using phosgene as a raw material can be employed. In this case, the above “using phosgene as a raw material” means
Not only in the case where phosgene is used as a direct raw material of the resin, an intermediate of the resin is manufactured using phosgene as a raw material,
This also includes the case where the above-mentioned resin is produced using the same. As a method for producing a resin having a known carbonate bond, usually, when a polycarbonate resin is obtained by reacting a diphenol and a carbonate raw material, as a carbonate raw material as a carbonate raw material,
This is a method using phosgene or a carbonate raw material using phosgene as a raw material. In particular, 1) phosgene and diphenols are subjected to interfacial polycondensation conditions,
Or 2) reacting phosgene with a monohydroxy aromatic compound such as phenol to produce a diaryl carbonate such as diphenyl carbonate, and subjecting this to diphenols, for example, under melt polycondensation conditions. 3) reacting phosgene with a monohydric alcohol such as methanol to produce a dialkyl carbonate such as dimethyl carbonate, and subjecting this to a transesterification reaction with a monohydroxy aromatic compound such as phenol to diphenyl carbonate or the like; A method of producing a diaryl carbonate of the above, and reacting the diaryl carbonate with a diphenol under the conditions of, for example, melt polycondensation.

(2) Raw Materials (a) Phosgene Chlorine Concentration Phosgene used in the method for producing a carbonate resin having a low volatile chlorine of the present invention is in a liquid or gaseous state and has a chlorine concentration of 1,000 ppb in the raw material phosgene. Or less, preferably 500 ppb or less, more preferably 10 ppb or less.
It is important that those having 0 ppb or less, particularly preferably 0 to 100 ppb, be used. The phosgene used is usually obtained from the reaction of carbon monoxide with chlorine and contains significant amounts of chlorine. Examples of a method for keeping chlorine in the raw material phosgene within the above range include adsorption removal of chlorine by an adsorbent such as activated carbon and separation removal by distillation using a boiling point difference, and may be removed by any method. . However, in the case of distillation removal, the order of removal is an extremely low value, and a considerable number of distillation stages are required. Therefore, adsorption removal using an adsorbent such as activated carbon is more advantageous. As the adsorbent that can be used in the present invention, besides activated carbon, those containing metals such as mercury and antimony, and various types such as zeolite and alumina can be used, and in any case, the amount of chlorine in phosgene can be reduced. It is necessary that the above-mentioned predetermined amount can be obtained. Further, the particle size of these adsorbents is preferably finer, and usually passes through a 2-mesh sieve, preferably passes through an 8-mesh sieve, and more preferably passes through a 16-mesh sieve.
It passes through a mesh sieve, more preferably about 32 mesh sieve. On the other hand, if the particle size is too small, there is an industrial problem. Therefore, the lower limit is about 60 mesh sieve remaining, and preferably 8 mesh sieve to 60 mesh sieve remaining. As the activated carbon to be used, activated carbon for acidic gas, activated carbon for basic gas and activated carbon for general gas can be used. Among them, activated carbon for acidic gas having the following physical properties is preferable. True density: 1.9 to 2.2 g / cc Porosity: 33 to 55% Specific surface area: 700 to 1500 m ² / g Pore volume: 0.5 to 1.1 cc / g Average particle size: 12 to 40 Å The particle size of the activated carbon is the same as the particle size range of the adsorbent described above. Further, from the viewpoint of temperature control, phosgene is preferably in a liquid state, and particularly in the case of adsorption removal, the phosgene is advantageous. When the reaction is carried out in a liquid state, a reaction pressure capable of maintaining the liquid state at each reaction temperature is selected. In the present invention, the method of adsorption removal is not particularly limited. For example, the liquefied phosgene is kept in a liquid state in an activated carbon tower, and the space velocity (SV) is usually 2 to 20, preferably 5 to 20, and the temperature is usually 5 to 5. It can be adsorbed and removed by a method of passing the liquid at a temperature of not more than ℃, for example, -5 ℃.

(B) Diphenol The diphenol used in the method for producing a carbonate resin having a low volatile chlorine of the present invention preferably corresponds to the general formula HO-Z-OH. Here, Z is one or more aromatic nuclei, and the hydrogen bonded to the carbon of the nucleus can be replaced by chlorine, bromine, an aliphatic group or an alicyclic group. A plurality of aromatic nuclei may each have a different substituent. Further, a plurality of aromatic nuclei may be bonded by a cross-linking group. The bridging group includes an aliphatic group, an alicyclic group, a heteroatom, or a combination thereof. Specifically, hydroquinone,
Resorcinol, dihydroxydiphenol, bis (hydroxyphenyl) alkane, bis (hydroxyphenyl)
Cycloalkane, bis (hydroxyphenyl) sulfide, bis (hydroxyphenyl) ether, bis (hydroxyphenyl) ketone, bis (hydroxyphenyl)
Sulfone, bis (hydroxyphenyl) sulfoxide,
Examples include bis (hydroxyphenyl) dialkylbenzenes and derivatives thereof having an alkyl or halogen substituent on the nucleus. Of course, two or more of these diphenols can be used in combination. These diphenols and other suitable diphenols include, for example, U.S. Pat. Nos. 4,982,014 and 3,023.
No. 8,365, No. 2,999,835, No. 3,1
No. 48,172, No. 3,275,601, No. 2,
Nos. 991,273, 3,271,367, 3,062,781, 2,970,131, and
Nos. 2,999,846, German Patent Publication Nos. 1,570,703 and 2,063,050,
Nos. 2,063,052 and 2,211,9
No. 56 and French Patent No. 1,56
No. 1,518. Particularly preferred diphenols include 2,2-bis (4-hydroxyphenyl) propane and 2,2-bis (3,5-dimethyl-4
-Hydroxyphenyl) propane, 1,1-bis (4-
(Hydroxyphenyl) cyclohexane and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane. Among them, it is preferable to use 2,2-bis (4-hydroxyphenyl) propane (bisphenol A).

(C) Others In the present invention, an optional chain terminator and / or branching agent can be added as required when producing a polycarbonate resin. The chain terminators suitable chain terminators, various monophenols, for example, in addition to ordinary phenol, C ₁ -C ₁₀ alkyl phenols such as p-t-butylphenol and p- cresol, and, p- chlorophenol And 2,
Halogenated phenols such as 4,6-tribromophenol are included. Among these, phenol, cumylphenol, isooctylphenol, and pt
-Butyl phenol is a preferred chain terminator. The amount of the chain terminator varies depending on the molecular weight of the target condensate, but is usually used in an amount of 0.5 to 10% by weight based on the amount of diphenol in the aqueous phase.

The branching agent used can be selected from a variety of compounds having three or more functional groups. Suitable branching agents include compounds having three or more phenolic hydroxyl groups, 2,4-bis (4-hydroxyphenyl-isopropyl) phenol, 2,6-bis (2'-hydroxy-5). '-Methylbenzyl) -4-methylphenol, 2- (4-hydroxyphenyl) -2
-(2,4-hydroxyphenyl) propane and 1,4
-Bis (4,4'-dihydroxytriphenylmethyl)
Contains benzene. In addition, compounds having three functional groups, 2,4-dihydroxybenzoic acid, trimesic acid, cyanuric chloride, bis (4-hydroxyphenyl)-
2-oxo-2,3-dihydroxyindole and 3,
3-bis (4-hydroxy-3-methylphenyl) -2
-Oxo-2,3-dihydroindole is also included. Among them, those having three or more phenolic hydroxy groups are preferred. The amount of the branching agent used varies depending on the desired degree of branching, but is usually used in an amount of 0.05 to 2 mol% based on the amount of diphenol in the aqueous phase.

(3) Polycondensation reaction (a) Reaction conditions As described above, a method for producing a resin having a polycarbonate bond using phosgene as a raw material typically includes the following: 1) an interface between phosgene and diphenols; Under polycondensation conditions,
Or 2) reacting phosgene with a monohydroxy aromatic compound such as phenol to produce a diaryl carbonate such as diphenyl carbonate, and subjecting this to diphenols, for example, under melt polycondensation conditions. 3) reacting phosgene with a monohydric alcohol such as methanol to produce a dialkyl carbonate such as dimethyl carbonate, and subjecting this to a transesterification reaction with a monohydroxy aromatic compound such as phenol to diphenyl carbonate or the like; A method in which a diaryl carbonate is produced and reacted with a diphenol, for example, under melt polycondensation conditions. Hereinafter, an interfacial polycondensation method, which is the most typical production method at present, will be described. [Interfacial polycondensation method] Generally, a method in which diphenols and phosgene are reacted in the presence of water and an organic solvent, and usually an alkali metal salt of diphenols and phosgene in an aqueous phase are reacted with an organic solvent. The reaction is carried out in the presence of
The polycarbonate oligomer thus obtained is usually further subjected to a polycondensation reaction to become a high molecular weight polymer. Solvent The organic solvent to be used in the present invention dissolves phosgene and reaction products such as carbonate oligomers and polycarbonate at the reaction temperature and reaction pressure, but does not dissolve water (does not form a homogeneous solution with water). It is important to include any inert organic solvents. Representative inert organic solvents include aliphatic hydrocarbons such as hexane and n-heptane, methylene chloride, chloroform,
Halogenated aliphatic hydrocarbons such as carbon tetrachloride, dichloroethane, trichloroethane, tetrachloroethane, dichloropropane and 1,2-dichloroethylene, aromatic hydrocarbons such as benzene, toluene and xylene, chlorobenzene, o-dichlorobenzene and chloro Halogenated aromatic hydrocarbons such as toluene, as well as substituted aromatic hydrocarbons such as nitrobenzene and acetophenone are included. Among them, halogenated hydrocarbons such as methylene chloride or chlorobenzene are preferably used. These inert organic solvents can be used alone or as a mixture with other solvents.

However, when chlorobenzene is used alone, it is necessary to use high operating temperatures during the reaction and washing in order to obtain a technically useful concentration of polycarbonate in chlorobenzene. Also, 2,2-
A suitable solvent combination for industrially important polycarbonates based on bis (4-hydroxyphenyl) propane is a mixture of methylene chloride and toluene, which, if necessary, is also used in the process according to the invention. be able to. The aqueous phase preferably contains at least three components of water, diphenol and alkali metal hydroxide. In such an aqueous phase, the diphenol reacts with an alkali metal hydroxide, such as sodium hydroxide or potassium hydroxide, to form a water-soluble alkali metal salt. Of course, before contacting the organic phase, it is preferable to mix the three components to prepare a uniform aqueous solution and prepare an aqueous phase in advance. Some or all of them can be mixed upon contact with the organic phase. The molar ratio of the diphenol and an alkali metal hydroxide in an amount ratio aqueous phase, 1: 1.8 to 1: 3.5 is preferred, and 1:
2.0-1: 3.2 is preferred. When preparing such an aqueous solution, the temperature should be 20 ° C. or higher, preferably 30 to 4 ° C.
Although the temperature is preferably set to 0 ° C., if the temperature is too high, the oxidation of diphenol occurs. Therefore, it is preferable that the temperature is set to the minimum necessary temperature and that the reaction is performed in a nitrogen atmosphere or that a small amount of a reducing agent such as hydrosulfide is added. The preferred amount of phosgene used is also affected by the reaction conditions, especially the reaction temperature and the concentration of the diphenol alkali metal salt in the aqueous phase,
It is usually 1-2 mol, preferably 1.05-1.5 mol, per 1 mol of diphenol. If this ratio is too large, the amount of unreacted phosgene increases and the basic unit deteriorates extremely. On the other hand, if it is too small, the CO group will be insufficient, and proper molecular weight extension will not be performed.

(B) Catalyst In the present invention, before the contact with phosgene, a polycondensation catalyst is supplied at the time of contact between the aqueous phase and the organic phase. May be performed at the time of contact. The polycondensation catalyst can be arbitrarily selected from many polycondensation catalysts used in the two-phase interfacial polycondensation method. Among them, trialkylamine, N-ethylpyrrolidone, N-ethylpiperidine, N-ethylmorpholine, N-isopropylpiperidine and N-isopropylmorpholine are suitable, and triethylamine and N-ethylpiperidine are particularly suitable.

(C) Production of Oligomer At the stage of obtaining the oligomer, the concentration of the oligomer in the organic phase may be within a range in which the obtained oligomer is soluble in the organic phase. % By weight.
Further, the proportion of the organic phase is preferably 0.2 to 1.0 by volume with respect to the aqueous solution of the alkali metal hydroxide of diphenol, that is, the aqueous phase. The reaction temperature is usually 80 ° C or lower, preferably 60 ° C or lower, more preferably 10 to 50 ° C.
° C. If the reaction temperature is too high, it is difficult to control the side reaction, and if it is too low, the refrigerant load increases. Under such polycondensation conditions, the viscosity average molecular weight (M
v) is generally about 500 to 10,000, preferably 1600 to 4,500, but is not limited to this molecular weight.

(D) Polycondensation reaction The oligomer thus obtained is converted into a high-molecular polycarbonate under ordinary polycondensation conditions. In a preferred embodiment, the organic phase in which the oligomer is dissolved is separated from the aqueous phase, and if necessary, the above-mentioned inert organic solvent is added to adjust the concentration of the oligomer. That is, the amount of the solvent is adjusted so that the concentration of the polycarbonate in the organic phase obtained by the polycondensation is 5 to 30% by weight. Thereafter, a water phase containing water and an alkali metal hydroxide is newly added, and in order to further prepare polycondensation conditions,
Preferably, the polycondensation catalyst described above is added to complete the desired polycondensation according to the two-phase interfacial polycondensation method. The ratio of the organic phase and the aqueous phase at the time of polycondensation is expressed by volume ratio: organic phase: aqueous phase = 1:
About 0.2 to 1 is preferable. After the completion of the polycondensation, a washing treatment with an alkali such as NaOH is performed until the remaining chloroformate group becomes 0.01 μeq / g or less. Thereafter, the organic phase is washed until the electrolyte is exhausted, and finally, the inert organic solvent is appropriately removed from the organic phase, and then the polycarbonate is separated.

[II] Polycarbonate resin The viscosity average molecular weight (Mv) of the polycarbonate resin thus obtained is usually from 10,000 to 100,000.
0, preferably 12,000 to 35,000
It is about. The viscosity average molecular weight (Mv) means that the concentration (C) of the oligomer or polycarbonate is 0.6 g.
/ Dl methylene chloride solution, the following formulas (1) and (2) were obtained from the specific viscosity (ηsp) measured at a temperature of 20 ° C.
It is a value calculated by using. ηsp / C = [η] (1 + 0.28ηsp) Formula (1) [η] = 1.23 × 10 ⁻⁵ Mv ^0.83 Formula (2) The polycarbonate thus obtained is measured by the method described below. The amount of chlorine generated by heating (the amount of chlorine generated per polymer (ppb)) can be reduced to 30 ppb or less, preferably 20 ppb or less, particularly preferably about 1 to 20 ppb. Therefore, such a polycarbonate resin having a small amount of volatile chlorine has advantages such as being hardly discolored even during molding.

The polycarbonate obtained by the method for producing a polycarbonate resin having a low volatile chlorine of the present invention can be obtained by adding various additives during the separation of the polycarbonate resin from the reactor, or before or during the processing thereof. For example,
Stabilizer, mold release agent, combustion retarder, antistatic agent, filler,
An effective amount of fiber, impact strength modifier, etc. can be added.

[III] Applications These polycarbonates can be processed into various molded articles, for example, films, yarns, plates, etc. by injection molding, extrusion molding, etc., and can be processed in various technical fields, for example, electric parts or In the building industry, and also for lighting equipment and optical equipment materials, in particular lighting housings, optical lenses,
Used for optical discs and audio discs.
In particular, when used in electric and electronic containers, this volatile chlorine as an impurity is disliked, and a polycarbonate resin having a small amount of volatile chlorine is extremely useful. The molded article of polycarbonate obtained by the present invention not only has excellent physical properties unique to polycarbonate, but also has significantly improved thermal stability in high-temperature molding, a small change in hue after melt molding, and a molded article with little coloring. Since it can be obtained, it has an advantage that its application range can be greatly expanded as compared with conventional products.

[0021]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist. [I] Preparation of phosgene Raw liquefied phosgene was charged into an activated carbon tower filled with activated carbon for acidic gas having the following physical properties (manufactured by Takeda, trade name: Shirasagi GH2X4 / 6UG) in a cylindrical container having a diameter of 55 mm and a height of 500 mm. The solution was passed at 5 ° C., 7.2 kg / hour and space velocity (SV) = 4. By repeatedly performing this liquid passing treatment, the chlorine content in the liquefied phosgene at the outlet of the activated carbon tower was reduced to 0 ppb. The chlorine content in the phosgene before the activated carbon treatment shown in Tables 1 and 2 was obtained by adding chlorine gas to the liquefied phosgene whose chlorine content was reduced to 0 ppb by performing the above-mentioned liquid passing treatment. The concentration of chlorine gas was adjusted by adding it. Further, the chlorine content in phosgene after the activated carbon treatment shown in Table 1 is a value after the liquefied phosgene whose concentration has been adjusted is further passed through an activated carbon tower. Physical particle size of activated carbon for acid gas : Pass through 4 mesh sieve to 6 mesh sieve residual Degree of vacuum: 2.1 g / cc Porosity: 40% Specific surface area: 1200 m ² / g Pore volume: 0.86 cc / g Average pore size: 12 Angstrom

[II] Production of polycarbonate resin Examples 1-5 Bisphenol A (BPA) 15.09 kg / h, sodium hydroxide (NaOH) 5.49 kg / h and water 9
3.5 kg / hour is converted to hydrosulfite 0.017 k
g / h, dissolved at 35 ° C. and then cooled to 25 ° C. in water phase and methylene chloride 61.9 cooled to 5 ° C.
kg / h of the organic phase are supplied to a Teflon pipe having an inner diameter of 6 mm and an outer diameter of 8 mm, respectively, and connected to the pipe, cooled to 0 ° C. separately introduced in a Teflon pipe reactor having an inner diameter of 6 mm and a length of 34 m. The chlorinated phosgene having a chlorine content shown in Table 1 was contacted with 7.2 kg / h. The raw material (bisphenol A / sodium hydroxide solution) was subjected to phosgenation and oligomerization while phosgene and a pipe reactor flowed at a linear velocity of 1.7 m / sec for 20 seconds. At this time, the reaction temperature was set to 60
° C was reached. The temperature of the reaction was controlled by external cooling to 35 ° C. before entering the next oligomerization bath. 0.005 kg of triethylamine as a catalyst for oligomerization
/ H, and 0.39 kg / h of pt-butylphenol were used as molecular weight regulators, each of which was introduced into the oligomerization tank.

The thus obtained oligomerized emulsion obtained from the pipe reactor is further introduced into a reaction vessel having a stirrer having an inner volume of 50 liters, and is stirred at 30 ° C. in a nitrogen gas (N ₂ ) atmosphere. After complete consumption of the unreacted sodium salt of bisphenol A (BPA-Na) present in the aqueous phase, the aqueous phase and the oil phase are allowed to stand and separated to obtain a methylene chloride solution of the oligomer. Was.

23 kg of the above methylene chloride solution of the oligomer was charged into a 70-liter reaction tank equipped with Faudler blades, and 10 k of methylene chloride for dilution was added thereto.
g of water, 2.2 kg of a 25% by weight aqueous sodium hydroxide solution, 6 kg of water and 2.2 g of triethylamine were added, and the mixture was stirred at 30 ° C. under a nitrogen gas atmosphere, and subjected to a polycondensation reaction for 60 minutes to obtain a polycarbonate resin. Was.

To this reaction solution, 30 kg of methylene chloride and 7 kg of water were added, and after stirring for 20 minutes, the stirring was stopped.
The aqueous and organic phases were separated. 0.1N to the separated organic phase
After adding 20 kg of hydrochloric acid and stirring for 15 minutes to extract triethylamine and a small amount of remaining alkaline component, the stirring was stopped and the aqueous phase and the organic phase were separated. Further, 20 kg of pure water was added to the separated organic phase, and after stirring for 15 minutes, the stirring was stopped, and the aqueous phase and the organic phase were separated. This operation was repeated until no chlorine ions in the extraction wastewater were detected (three times). The obtained purified polycarbonate solution was powdered by feeding it into warm water at 40 ° C., and dried to obtain a granular powder (flake). The nitrogen content in the flakes is 1.5
ppm.

The chlorine content in phosgene was measured by collecting 70 g of phosgene, vaporizing it, absorbing it into a NaOH solution,
Oxidation-reduction titration was performed as ClO, the absolute amount was measured, and the result was defined as the chlorine content in phosgene. The average molecular weight of the oligomer obtained in each example, the average molecular weight and the molecular weight distribution of the flake, and the color tone of the molded product were measured. Table 1 shows the results. Example 6 As a separately introduced liquefied phosgene cooled to 0 ° C., 5
Activated carbon (manufactured by Ohira Chemical Co., Ltd., trade name: Yashikol M) is filled in a cylindrical container of 5 mmφ * 500 mmL, and then charged at −5 ° C. and 7.
Except that phosgene passed through at 2 kg / hr was used, the procedure was the same as in Example 1. Table 1 shows the results. Particle size: passing through 8 mesh sieve to 30 mesh sieve residue Vacuum degree: 2.0 to 2.2 g / cc Porosity: 33 to 45% Specific surface area: 700 to 1500 m ² / g Average pore size: 12 to 40 Å

[III] Evaluation of Physical Properties The physical properties of the polycarbonate resins in Table 1 were evaluated as follows. (1) Molecular weight distribution (Mw / Mn): GPC (Gel Pe)
using a chromatography (trade name: HLC-8020, manufactured by Tosoh Corporation) using tetrahydrofuran (THF) as an eluent.
Kinds of high-speed GPC filler (Tosoh Corp., product name: T
SK 5000HLX, 4000HLX, 3000HL
X and 2000HLX) were separated by four columns packed and detected by the difference in refractive index.
w and Mn were determined in terms of polystyrene, and Mw / Mn was calculated.

(2) Color tone (YI): [Formation of sample plate] The flakes were plasticized at 280 ° C. using an injection molding machine (manufactured by Nissei Plastic Industry Co., Ltd., product name: FS80S-12ASE), and then cylinders were formed. For 15 seconds, a sample plate having a thickness of 3.2 mm and a square of 60 mm was formed.
Also, after plasticization, a sample plate having a residence time in the cylinder of 5 minutes was formed. [Measurement of Color Tone] These sample plates were measured using a color difference meter (manufactured by Suga Test Instruments Co., Ltd., product name: SM-4-CH).
The color tone (YI value) was measured. Of the measured values, a small YI value for 15 seconds retention indicates that the color tone during steady molding is good, and the difference between the 15 seconds and 5 minutes retention YI values (ΔY
The fact that I) is small indicates that the thermal stability at high temperatures is good.

(3) Measurement of the amount of volatile chlorine: 2
After heating at 80 ° C. for 30 minutes, it was evaluated by measuring the amount of chlorine generated by heating when it was kept at room temperature for 3 days. The flakes were kneaded at a resin temperature of 290 ° C. in a 30 mm twin-screw extruder (made by Ikegai Iron and Steel) and then pelletized. Relates that contamination of chlorine is concerned on the operation this time (H ₂ 0 for use in a human hand and sweat and cooling) and treated Careful attention. 10 g of the obtained pellets were charged into a glass tube having an inner diameter of 10 mm, which had been washed with ion chromatography water, and sealed under vacuum (the length of the sealed tube was constant at 20 cm). The whole glass tube was kept standing in an oil bath at 280 ° C. for 30 minutes, cooled, washed thoroughly with oil and the like adhering to the outside, and then kept at room temperature for 3 days while keeping the glass tube as it was. The portion immediately above the infiltrated portion of the polymer was cut (fired) and the inside of the upper glass was washed with 1 ml of pure water, collected, analyzed by ion chromatography, and determined as the amount of chlorine generated by heating per 1 g of the polymer.

[0030]

[Table 1]

Comparative Examples 1 to 3 In Example 1, liquefied phosgene prepared by adjusting the chlorine content in phosgene to the concentration shown in Table 2 was used, and the phosgene was carried out without passing through an activated carbon tower. Example 1
The same operation as described above was performed.

[0032]

[Table 2]

[0033]

As described above, the polycarbonate resin having a low volatile chlorine content of the present invention has a small amount of chlorine which gradually evaporates when held at room temperature and has a stable quality. In addition, the polycarbonate resin obtained by the production method of the present invention has, in addition to the above properties, significantly improved thermal stability in high-temperature molding, a small change in hue after melt molding, and a molded article with less coloring can be obtained. Therefore, there is an advantage that the range of use can be greatly expanded as compared with the conventional product.

Claims (13)

[Claims] 1. A polycarbonate resin having a small amount of volatile chlorine, wherein the amount of chlorine generated by heating when heated at 280 ° C. for 30 minutes and kept at room temperature for 3 days is 30 ppb or less. 2. The amount of chlorine generated by heating is 20 ppb or less.
The polycarbonate resin having a low volatile chlorine content according to claim 1. 3. The amount of chlorine generated by heating is 1 to 20 ppb.
The polycarbonate resin having a low volatile chlorine content according to claim 1 or 2. 4. A viscosity average molecular weight M of a polycarbonate resin.
2. The method of claim 1, wherein v is between 10,000 and 100,000.
4. The polycarbonate resin having a low content of volatile chlorine according to any one of items 1 to 3. 5. A method for producing a resin having a carbonate bond using phosgene as a raw material, characterized in that phosgene having a chlorine concentration of 1,000 ppb or less is used as a raw material phosgene, wherein a polycarbonate resin having a low volatile chlorine is produced. Method. 6. A method for producing a resin having a carbonate bond using phosgene as a raw material is a method for producing a polycarbonate resin by reacting phosgene or a carbonate raw material using phosgene as a raw material with a diphenol.
A method for producing a polycarbonate resin having a small amount of volatile chlorine according to claim 5. 7. The method for producing a polycarbonate resin having a low volatile chlorine according to claim 6, comprising a step of reacting a diphenol with phosgene in the presence of water and an organic solvent. 8. The method for producing a polycarbonate resin having a low volatile chlorine according to claim 6, wherein at least a part of the diphenols is reacted with phosgene as an alkali metal salt. 9. The method according to claim 7, comprising a step of reacting a diphenol with phosgene in the presence of water and an organic solvent, and a step of subjecting the polycarbonate oligomer obtained in the step to a polycondensation reaction to obtain a polycarbonate. 9. The method for producing a polycarbonate resin having a low volatile chlorine according to item 8. 10. The method for producing a polycarbonate resin having a low volatile chlorine according to claim 6, wherein a diaryl carbonate obtained by reacting phosgene with a monohydroxy aromatic compound is used as a carbonate raw material. 11. The phosgene used is phosgene obtained by reacting carbon monoxide with chlorine.
11. The method for producing a polycarbonate resin having a low content of volatile chlorine according to any one of 10 above. 12. The method for producing a polycarbonate resin having a small amount of volatile chlorine according to claim 11, wherein phosgene obtained by a reaction between carbon monoxide and chlorine is subjected to an adsorption treatment. 13. The method according to claim 12, wherein the adsorption treatment is carried out using activated carbon.