JP2014074107A - Method for producing polycarbonate resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for effectively and stably producing a polycarbonate resin which is excellent in heat resistance, heat stability, hue and optical characteristics, can be melt-molded and is reduced in foreign materials.SOLUTION: There is provided a method for producing a polycarbonate resin obtained by polycondensing a raw material composition containing at least a dihydroxy compound represented by a spiroglycol derivative and a fluorene derivative and a carbonic acid diester. The dihydroxy compound, which is a spiroglycol derivative, is 50 mol% or more based on the total dihydroxy compound in the raw material composition, and the polycarbonate resin is filtered with a filter having a filter medium composed of a metal non-woven fabric subjected to heat treatment at 330°C or more and 600°C or less.

Description

  The present invention relates to a method for efficiently and stably producing a polycarbonate resin that is excellent in heat resistance, thermal stability, hue, and optical characteristics and has few foreign substances. The present invention also relates to an optical film having a low photoelastic coefficient made of the polycarbonate resin, having few foreign matters, and exhibiting a specific phase difference when stretched.

  Polycarbonate resins generally use 2,2-bis (4-hydroxyphenyl) propane (hereinafter sometimes abbreviated as bisphenol A) as a monomer component, and make use of advantages such as transparency, heat resistance, and mechanical strength. It is widely used as so-called engineering plastics in the optical field such as electrical / electronic parts, automotive parts, optical recording media, and lenses. However, for retardation film applications and lens applications such as flat panel displays, which have been rapidly spreading recently, more advanced optical properties such as low birefringence and low photoelastic coefficient have been required. Aromatic polycarbonate resins having A as a monomer component cannot meet the demand.

  In order to solve the above problems, a polycarbonate resin using 9,9-bis (4-hydroxy-3-methylphenyl) fluorene and bisphenol A as raw materials has been proposed (for example, see Patent Document 1). However, the polycarbonate resin described in Patent Document 1 has a high glass transition temperature, and a film before stretching (hereinafter sometimes abbreviated as a raw film) is a film made of a solution in which a resin and a solvent are mixed. It is formed into a film by the solution casting method to shape | mold.

  In order to enable melt film formation of the raw film, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene (hereinafter sometimes abbreviated as BCF) and 3,9-bis (1 , 1-dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane (hereinafter sometimes abbreviated as spiroglycol) has been proposed. (For example, see Patent Documents 2 to 7). By copolycondensation of spiroglycol with BCF, the glass transition temperature can be lowered, and not only melt film formation is possible, but also suitable heat resistance and low photoelastic coefficient can be expressed. Applications as optical films such as retardation films are expected.

Japanese Patent No. 3561195 International Publication No. 2008/156186 Pamphlet JP 2011-26499 A International Publication No. 2010/071079 Pamphlet JP 2011-148942 A JP 2011-162604 A International Publication No. 2012/063965 Pamphlet

In the solution casting method as described in Patent Document 1, the solvent usually used in the film often remains, and the solvent used for the solution casting is dichloromethane, from the viewpoint of solubility, volatility, and nonflammability. In many cases, chlorinated solvents such as these are used, which not only has a large environmental impact during film formation, but also causes corrosion of equipment when processing into films, and the obtained films are used in image display devices. When used, there is a problem that the residual solvent adversely affects other parts. And since the glass transition temperature of the resin is high, there is a risk of resin coloring and decomposition due to high temperatures, and it is easy to solidify rapidly due to temperature drop during molding, for example, forming a uniform shape like a film stably For the reason that it is difficult to manufacture, it has been difficult to produce a film by a melt molding method in which a resin is melted and processed as it is.

  On the other hand, as described in Patent Documents 2 to 7, a polycarbonate resin obtained by copolycondensation of spiroglycol with BCF can reduce the glass transition temperature and can be formed into a film by a melt film forming method. However, spiroglycol has an acetal structure in its skeleton, which is easily cleaved to become a polyfunctional branching component and causes the generation of foreign substances such as gels. There has been a problem that the performance required for a retardation film used for a specific application, particularly for a display or the like, cannot be satisfied.

  An object of the present invention is to provide a method for efficiently and stably producing a polycarbonate resin that is excellent in heat resistance, thermal stability, hue, optical properties, can be melt-molded, and has few foreign substances. There is. Another object of the present invention is to provide an optical film that has few foreign substances made of the polycarbonate resin and expresses a specific retardation by stretching.

  As a result of intensive studies to solve the above problems, the present inventor used a filter provided with a filter medium having a specific structure, which was subjected to a specific heat treatment in a method for producing a polycarbonate resin having a specific structure. The present inventors have found a method for stably producing a polycarbonate resin that is excellent in heat resistance, thermal stability, hue, optical properties, can be melt-molded, and has few foreign substances by filtering the polycarbonate resin. .

That is, the gist of the present invention resides in the following [1] to [29].
[1]
A method for producing a polycarbonate resin obtained by polycondensing a raw material composition containing at least a dihydroxy compound represented by the following formula (1) and the following formula (2) with a carbonic acid diester,
The dihydroxy compound represented by the following formula (1) is 50 mol% or more with respect to all dihydroxy compounds constituting the raw material composition,
A method for producing a polycarbonate resin, wherein the polycarbonate resin is filtered using a filter having a filter medium made of a metal nonwoven fabric heat-treated at a temperature of 330 ° C. or higher and 600 ° C. or lower.

(In the formula (1), R _{1 to} R ₄ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted carbon group having 5 to 20 carbon atoms. A cycloalkyl group or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms is represented.)

(In the formula (2), R _{5 to} R ₈ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted 6 to 20 carbon atoms. Represents a cycloalkyl group or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms.] [2]
The method for producing a polycarbonate resin according to [1], wherein the dihydroxy compound represented by the formula (2) is 5 mol% or more and 50 mol% or less with respect to all dihydroxy compounds constituting the raw material composition.
[3]
The method for producing a polycarbonate resin according to [1] or [2], wherein the heat treatment of the filter is performed in the presence of at least one of water vapor and oxygen.
[4]
The method for producing a polycarbonate resin according to any one of [1] to [3], wherein the filter is acid-treated [5].
The filter is stored in a container, and the value obtained by dividing the internal volume (m ³ ) of the storage container by the flow rate (m ³ / min) of the polycarbonate resin to be filtered is 2 to 10 minutes. ] The manufacturing method of the polycarbonate resin as described in any one of [4].
[6]
The method for producing a polycarbonate resin according to [5], wherein the polycarbonate resin is supplied from a lower part of the storage container of the filter, and the filtered polycarbonate resin is discharged from an upper part of the storage container.
[7]
The method for producing a polycarbonate resin according to any one of [1] to [6], wherein a linear velocity of the molten resin on the filter surface is 0.01 to 0.5 m / h.
[8]
The method for producing a polycarbonate resin according to any one of [1] to [7], wherein the filter has an opening of 50 μm or less.
[9]
The method for producing a polycarbonate resin according to any one of [1] to [8], wherein the temperature of the polycarbonate resin after filtration using the filter is 220 ° C or higher and 280 ° C or lower.
[10]
The polycarbonate resin according to any one of [1] to [9], wherein at least one of the dihydroxy compounds represented by the formulas (1) and (2) is filtered through a filter before the polycondensation reaction is performed. Manufacturing method.
[11]
The method for producing a polycarbonate resin according to any one of [1] to [10], wherein the glass transition temperature of the polycarbonate resin is 50 ° C. or higher and 180 ° C. or lower.
[12]
The reduced viscosity (ηsp / c) of the polycarbonate resin is 0.3 dL / g or more, 0.6
The method for producing a polycarbonate resin according to any one of [1] to [11], which is dL / g or less.
[13]
The polycarbonate according to any one of [1] to [12], wherein the polycarbonate resin has a melt viscosity at a shear rate of 91.2 sec ⁻¹ measured at 260 ° C. of 500 Pa · s to 3000 Pa · s. Manufacturing method of resin.
[14]
The method for producing a polycarbonate resin according to any one of [1] to [13], wherein the polycarbonate resin obtained by the polycondensation is supplied to the filter in a molten state without being solidified and filtered.
[15]
The method for producing a polycarbonate resin according to any one of [1] to [14], wherein after the operation of devolatilizing the polycarbonate resin with an extruder having a vent port, the polycarbonate resin is supplied to the filter and filtered.
[16]
The screw of the extruder is composed of a plurality of elements, at least one of the elements is a kneading disk, and the total length of the kneading disk is 20% or less of the total length of the screw. [15] A method for producing a polycarbonate resin according to [15].
[17]
When the weight of the resin extruded per hour by the extruder is W (kg / h) and the cross-sectional area of the barrel of the extruder is S (m ² ), the following formula (4) is satisfied [15] Or the manufacturing method of polycarbonate resin as described in [16].

12000 ≤ W / S ≤ 60000 (4)
[18]
The method for producing a polycarbonate resin according to any one of [15] to [17], wherein the temperature of the polycarbonate resin supplied to the extruder is 200 ° C. or higher and 280 ° C. or lower. [19]
The method for producing a polycarbonate resin according to any one of [1] to [18], wherein the temperature of the polycarbonate resin supplied to the filter is 230 ° C. or higher and 280 ° C. or lower. [20]
The barrel constituting the extruder includes a plurality of heaters, and in at least one combination of the heaters, the set temperature of the heater is not higher than the heater set temperature adjacent to the polycarbonate resin supply side of the extruder, [15] The method for producing a polycarbonate resin according to any one of [19].
[21]
The method for producing a polycarbonate resin according to any one of [15] to [20], wherein a gear pump is disposed between the extruder and the filter.
[22]
The method for producing a polycarbonate resin according to any one of [1] to [21], wherein the content of the aromatic monohydroxy compound contained in the polycarbonate resin is 1 ppm by weight or more and 1000 ppm by weight or less.
[23]
The polycondensation is performed using a catalyst;
The catalyst is a compound containing at least one metal selected from the group consisting of metals of Group 1 or Group 2 of the long-period periodic table, and is used in an amount of 10 μmol or more as a metal amount with respect to 1 mol of all dihydroxy compounds. ] The manufacturing method of the polycarbonate resin as described in any one of [22].
[24]
The method for producing a polycarbonate resin according to [23], wherein the catalyst is a compound containing at least one metal selected from the group consisting of a metal of Group 2 of the long-period periodic table and lithium.
[25]
The method for producing a polycarbonate resin according to any one of [1] to [24], wherein the dihydroxy compound represented by the formula (1) has a pH of 5 or more.
[26]
The film obtained by shape | molding the polycarbonate resin obtained by the manufacturing method of the polycarbonate resin as described in any one of [1] thru | or [25] by melt extrusion.
[27]
A retardation film formed by stretching the film according to [26] and satisfying the relationship of the following formula (6).
0.70 <R (450) / R (550) <1.00 (6)
(However, R (450) and R (550) represent retardation values in the film plane at wavelengths of 450 nm and 550 nm, respectively).

  According to the present invention, such as a retardation film used in flat panel displays such as liquid crystal and organic EL, etc., having performance applicable to optical applications, excellent in heat resistance, thermal stability, hue, and optical characteristics, In addition, it is possible to efficiently and stably produce a polycarbonate resin that can be melt-molded and has few foreign substances.

It is a figure which shows an example of the manufacturing apparatus which concerns on the manufacturing method of the polycarbonate of this invention.

DESCRIPTION OF EMBODIMENTS Embodiments of the present invention will be described in detail below. However, the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention. It is not limited to the contents. In addition, when the expression “to” is used in the present specification, it is used in a sense including numerical values or physical values before and after the expression.
The present invention is a method for producing a polycarbonate resin obtained by polycondensing a raw material composition containing at least a dihydroxy compound represented by the following formula (1) and the following formula (2) with a carbonic acid diester,
The dihydroxy compound represented by the following formula (1) is 50 mol% or more with respect to all dihydroxy compounds constituting the raw material composition,
It exists in the manufacturing method of polycarbonate resin which filters the said polycarbonate resin using the filter which has a filter medium consisting of the metal nonwoven fabric heat-processed at the temperature of 330 degreeC or more and 600 degrees C or less.

In the formula (1), R _{1 to} R ₄ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cyclohexane having 5 to 20 carbon atoms. It represents an alkyl group or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms. In the formula (2), R _{5 to} R ₈ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted 6 to 20 carbon atoms. Or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms.

<Raw material composition and polycondensation catalyst>
(Dihydroxy compound)
In the method for producing a polycarbonate resin of the present invention, at least a specific dihydroxy compound represented by the following formula (1) is used as a raw material.

(In the formula (1), R _{1 to} R ₄ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted carbon group having 5 to 20 carbon atoms. A cycloalkyl group or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms.) Among them, from the viewpoint of easy availability and reduction of photoelastic coefficient, all of R _{1 to} R ₄ Spiroglycol in which is a methyl group is preferred.

The dihydroxy compound represented by the formula (1) needs to be 50 mol% or more, preferably 55 mol% or more, more preferably 60 mol% or more with respect to all dihydroxy compounds constituting the polycarbonate resin of the present invention. Especially preferably, it is 65 mol% or more. When the content of the dihydroxy compound represented by the formula (1) is small, the glass transition temperature becomes excessively high, so that it becomes difficult to melt-mold and form a film of the obtained polycarbonate resin, and filtration described later is difficult. In addition, there is a possibility that predetermined optical characteristics cannot be obtained. On the other hand, if the content of the dihydroxy compound represented by the formula (1) is too large, not only the predetermined optical characteristics may not be obtained, but heat resistance may be deteriorated. Preferably it is 80 mol% or less, More preferably, it is 75 mol% or less.

  The dihydroxy compound represented by the formula (1) may be obtained by using an acid in the production process, and a trace amount of an acid component that is not completely removed in the purification process promotes the cleavage of the acetal structure. The occurrence of foreign substances in the polycarbonate resin may be promoted. In particular, in the present invention in which polycondensation is carried out by transesterifying a dihydroxy compound and a carbonic acid diester, since the reaction requires a high temperature, the influence of a small amount of an acid component tends to appear more strongly. The pH value of the dihydroxy compound is preferably 5.0 or more, more preferably 5.5 or more, and particularly preferably 6.0 or more. On the other hand, if the pH value is too high, the basic component acts as a catalyst, which not only destabilizes the polycondensation reaction, but may also cause a deterioration in the hue of the resulting polycarbonate resin. 0.0 or less is preferable, more preferably 8.5 or less, and particularly preferably 8.0 or less.

  The pH value of the dihydroxy compound represented by the formula (1) may be determined by a generally known method for measuring the pH value of an aqueous solution, for example, by a method for measuring a pH value using a glass electrode. More specifically, a pH value as shown in JIS Z8802 is obtained by mixing a liquid obtained by mixing pure water containing no substance that affects the pH value and the dihydroxy compound represented by the above formula (1). It can be measured by the method. More specifically, the dihydroxy compound represented by the formula (1) is mixed with pure water having an electric conductivity of 0.1 μs / cm or less at 25 ° C. so that the weight ratio is 1/1000. After stirring the liquid for 10 minutes with a stirrer, the pH can be measured with a glass electrode pH meter while the stirring state is maintained. The pH value can be controlled by sufficiently neutralizing with the basic compound or using the basic compound slightly more than the neutralization point during the purification of the dihydroxy compound represented by the formula (1). . Usually, since the dihydroxy compound represented by the formula (1) is often purified by crystallization, the crystal is suspended and washed in the presence of a basic compound, or the crystal is recovered by centrifugation or filtration. At this time, it is preferable to control the pH by washing with a basic compound. The crystals once obtained can be again subjected to treatment such as suspension washing in the presence of a basic compound. After such treatment, it can be washed with water or an organic solvent as necessary.

Examples of the basic compound include a metal compound of Group 1 or Group 2 (hereinafter simply referred to as “Group 1” or “Group 2”), a basic boron compound, a basic phosphorus compound in the long-period periodic table, Examples include basic compounds such as basic ammonium compounds and amine compounds, among which hydroxides and carbonates of Group 1 or Group 2 metals are preferred from the viewpoint of easy handling and availability.
In the method for producing a polycarbonate resin of the present invention, at least a specific dihydroxy compound represented by the following formula (2) is used as a raw material together with the dihydroxy compound represented by the above formula (1).

(In the formula (2), R _{5 to} R ₈ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted 6 to 20 carbon atoms. Among them, a cycloalkyl group or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms.) From the viewpoint of easy availability and imparting optical properties, 9,9-bis (4- Hydroxy-3-methylphenyl) fluorene (hereinafter sometimes abbreviated as BCF) and 9,9-bis (4-hydroxyphenyl) fluorene are preferred, and BCF is preferred from the viewpoint of ease of handling.

The dihydroxy compound represented by the formula (2) is preferably 5 mol% or more, more preferably 10 mol% or more, still more preferably 20 mol% or more with respect to all dihydroxy compounds constituting the polycarbonate resin of the present invention. Particularly preferred is 25 mol% or more, and particularly preferred is 30 mol% or more.
If the content of the dihydroxy compound represented by the formula (2) is small, the glass transition temperature is excessively lowered, and the heat resistance of the obtained polycarbonate resin may be deteriorated. May not be able to obtain the desired characteristics.

  On the other hand, if the content of the dihydroxy compound represented by the formula (1) is too large, not only the predetermined optical characteristics may not be obtained, but also the glass transition temperature becomes excessively high. The resulting polycarbonate resin may be difficult to be melt-molded or formed into a film, or may be difficult to filter, which will be described later. Therefore, it is usually at most 50 mol%, preferably at most 45 mol%, more preferably at most 40 mol%, particularly Preferably it is 35 mol% or less.

  Examples of the predetermined optical characteristics include a phase difference and a photoelastic coefficient in addition to coloring and foreign matters that affect the light transmittance. In particular, when the polycarbonate resin of the present invention is used for a retardation film as a quarter-wave plate, it is important to have a retardation in the vicinity of a quarter of the wavelength in all wavelength regions. It is necessary to provide a so-called birefringent reverse wavelength dispersibility that becomes smaller as the wavelength becomes shorter and becomes larger as the wavelength becomes longer. The wavelength dispersion of birefringence can be evaluated by creating a stretched film having a uniform thickness, measuring the phase difference at a measurement wavelength of 450 nm and the phase difference at 550 nm, and obtaining these ratios. It is preferable to satisfy the following formula (6).

0.70 <R (450) / R (550) <1.00 (6)
(However, R (450) and R (550) represent retardation values in the film plane at wavelengths of 450 nm and 550 nm, respectively).
R (450) / R (550) in the present invention is more preferably 0.80 to 0.95, further preferably 0.85 to 0.93, and particularly preferably 0.87 to 0.91. In order to control R (450) / R (550), the molar ratio of the structural unit comprising the dihydroxy compound represented by the formula (2) in the polycarbonate resin of the present invention is controlled to an appropriate value. Is most important, but the molar ratio of the dihydroxy compound represented by the formula (1) and dihydroxy compounds other than the formulas (1) and (2) (hereinafter sometimes referred to as other dihydroxy compounds). Therefore, it is preferable to adjust the molar ratio as a whole.

The photoelastic coefficient of the polycarbonate resin of the present invention is preferably 40 × 10 ⁻¹² Pa ⁻¹ or less as a value measured by the method described in the Examples section below, and is 30 × 10 ⁻¹² Pa. ⁻¹ or less is more preferable, and 25 × 10 ⁻¹² Pa ⁻¹ or less is particularly preferable. If the photoelastic coefficient is too large, when used as a retardation film, the phenomenon that the retardation changes due to stress is likely to occur.For example, the retardation changes due to the stress when the retardation film is bonded to a polarizing plate. This may cause uneven color of the display and image quality degradation. The photoelastic coefficient greatly depends on the kind and composition of the dihydroxy compound component constituting the polycarbonate resin.

  In the production method of the polycarbonate resin of the present invention, the dihydroxy compound represented by the above formula (1) and the dihydroxy compound other than the dihydroxy compound represented by the above formula (2) (hereinafter abbreviated as other dihydroxy compounds) are used as raw materials. May also be used.

Specifically, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neo Aliphatic diols such as pentyl glycol, tetramethylcyclobutanediol, 1,2-cyclopentanediol, 1,3-cyclopentanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 2-methyl-1,4-cyclohexanediol, tricyclodecanediol, pentacyclodiol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 3,8-bis ( Hydroxymethyl) tricyclo [5. 1.02.6] decane, 3,9-bis (hydroxymethyl) tricyclo [5.2.1.02.6] decane, 4,8-bis (hydroxymethyl) tricyclo [5.2.1.02 .6] decane, 4,9-bis (hydroxymethyl) tricyclo [5.2.1.02.6] decane, 8-hydroxy-3-hydroxymethyltricyclo [5.2.1.02.6] decane 9-hydroxy-3-hydroxymethyltricyclo [5.2.12.02.6] decane, 8-hydroxy-4-hydroxymethyltricyclo [5.2.2.12.6] decane, 9-hydroxy Cycloaliphatic diols such as -4-hydroxymethyltricyclo [5.2.1.02.6] decane, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol 2, 2-bis (4-hydroxyphenyl) propane having a ring structure having an ether bond such as oxyalkylene glycol such as tripropylene glycol, polypropylene glycol and polytetramethylene glycol, isosorbide, isomannide and isoidet (= 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-diphenyl) phenyl) propane, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis (4-hydroxyphenyl) pentane, 2,4′- Dihydroxy-diphenylmethane, bis (4-hydroxyphenyl) me , Bis (4-hydroxy-5-nitrophenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) -2-ethylhexane, 1,1-bis (4-hydroxyphenyl) decane, 2,2-bis (4-hydroxyphenyl) octane, 2,2-bis (4-hydroxyphenyl) nonane, 2,2-bis (4-hydroxyphenyl) decane, 3,3 -Bis (4-hydroxyphenyl) pentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl) sulfone, 2,4'-dihydroxydiphenylsulfone, bis (4-hydroxyphenyl) sulfide, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxy-3,3′-dichlorodiphenyl ether Bisphenols such as 4,4′-dihydroxy-2,5-diethoxydiphenyl ether, 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene, 9,9-bis (4- (2- Hydroxyethoxy) -3-methylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-isopropylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3- Isobutylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-tert-butylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-cyclohexylphenyl) fluorene 9,9-bis (4- (2-hydroxyethoxy) -3-phenylphenyl) fluorene, 9,9-bis (4 (2-hydroxyethoxy) -3,5-dimethylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-tert-butyl-6-methylphenyl) fluorene, 9,9-bis ( Examples thereof include dihydroxy compounds having a fluorene structure such as 4- (3-hydroxy-2,2-dimethylpropoxy) phenyl) fluorene.
Among them, for imparting toughness, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, diethylene glycol, Triethylene glycol, polyethylene glycol, and polytetramethylene glycol are preferable, and isosorbide and bisphenol A are preferable for imparting heat resistance.

  Other dihydroxy compounds may be used singly or in combination of two or more, but for the expression of predetermined optical properties, other dihydroxy compounds may be used for all dihydroxy compounds constituting the polycarbonate resin of the present invention. The total of the dihydroxy compounds is preferably 30 mol% or less, more preferably 20 mol% or less, and particularly preferably 10 mol% or less.

  The polycarbonate resin of the present invention comprises a dihydroxy compound represented by the formula (1), a dihydroxy compound represented by the formula (2), a raw material composition containing other dihydroxy compounds as required, and a carbonic acid diester. In the presence of a catalyst, it is produced by a melt polycondensation method in which polycondensation is carried out while removing a monohydroxy compound by-produced by transesterification out of the system. Here, there is no particular limitation on the timing of mixing the dihydroxy compound constituting the raw material composition, and the raw material composition and the carbonic acid diester are finally supplied to the reaction vessel so that they can be transesterified in the presence of a catalyst. That's fine. For example, each dihydroxy compound may be separately supplied to the reaction vessel, or each dihydroxy compound and carbonic acid diester may be mixed in advance and supplied to the reaction vessel.

  Examples of the carbonic acid diester used in the present invention include those represented by the following general formula (7). These carbonic acid diesters may be used alone or in combination of two or more.

(A ¹ and A ² are substituted or unsubstituted C 1-18 aliphatic or substituted or unsubstituted aromatic groups, and A ¹ and A ² may be the same or different. )
A ¹ and A ² are preferably a substituted or unsubstituted aromatic hydrocarbon group, and more preferably an unsubstituted aromatic hydrocarbon group. In addition, examples of the substituent of the aliphatic hydrocarbon group include an ester group, an ether group, a carboxylic acid, an amide group, and a halogen. Examples of the substituent of the aromatic hydrocarbon group include an alkyl group such as a methyl group and an ethyl group. Is mentioned.

  Examples of the carbonic acid diester represented by the general formula (11) include substituted or unsubstituted diphenyl carbonate such as diphenyl carbonate and ditolyl carbonate, dialkyl carbonate such as dimethyl carbonate, diethyl carbonate, and di-t-butyl carbonate. Illustratively, preferred are diphenyl carbonate and substituted diphenyl carbonate, and particularly preferred is diphenyl carbonate. Carbonic acid diesters may contain impurities such as chloride ions, which may inhibit the polycondensation reaction or deteriorate the hue of the resulting polycarbonate resin. It is preferable to use a purified one.

  In the present invention, a polycarbonate resin is obtained by polycondensing a dihydroxy compound containing at least the dihydroxy compound represented by the formulas (1) and (2) and a carbonic acid diester by an ester exchange reaction. The raw material dihydroxy compound and carbonic acid diester can be transesterified even if they are supplied independently to the reaction vessel, but can also be mixed uniformly before the transesterification. The mixing temperature is preferably 80 ° C. or higher, preferably 90 ° C. or higher, and the upper limit thereof is preferably 250 ° C. or lower, preferably 200 ° C. or lower, more preferably 180 ° C. or lower, and particularly preferably 160 ° C. or lower. Among these, 100 ° C. or higher and 150 ° C. or lower is preferable. If the mixing temperature is too low, the dissolution rate may be slow or the solubility may be insufficient, often causing problems such as solidification or clogging of the raw material filter described later, and if the mixing temperature is too high, the heat of the dihydroxy compound Deterioration may be caused and the hue of the polycarbonate resin obtained as a result may deteriorate.

  In the present invention, the oxygen concentration in the operating environment in which the dihydroxy compound as the raw material and the carbonic acid diester are mixed is preferably 10 vol% or less, more preferably 0.0001 vol% to 10 vol%, especially 0.0001 vol% to 5 vol%, Performing in an atmosphere of 0.0001 vol% to 1 vol% is preferable from the viewpoint of preventing hue deterioration.

  In the present invention, the carbonic acid diester may be used in a molar ratio of 0.90 to 1.20, preferably 0.95 to 1.10, more preferably 0.97, based on all dihydroxy compounds used in the reaction. To 1.03, particularly preferably 0.99 to 1.02. When this molar ratio is decreased, the terminal hydroxyl group of the produced polycarbonate resin is increased, the thermal stability of the polymer is deteriorated, coloring occurs during molding, the rate of transesterification reaction is reduced, and the desired high molecular weight. The body may not be obtained. On the other hand, when this molar ratio is increased, the rate of transesterification reaction decreases, the production of polycarbonate having a desired molecular weight becomes difficult, the amount of residual carbonic diester in the polycarbonate resin increases, and during extrusion and molding In some cases, gas may be generated. The decrease in the transesterification reaction rate may increase the heat history in the polycondensation reaction, and may deteriorate the hue of the resulting polycarbonate resin.

In the present invention, in order to further reduce the foreign matters contained in the finally obtained polycarbonate resin, it is also effective to preliminarily filter with a raw material filter before supplying the raw material monomer to the polycondensation reaction tank.
The shape of the raw material filtration filter may be any type such as basket type, disc type, leaf disc type, tube type, flat cylindrical type, pleated cylindrical type, etc. A pleated type that can be taken is preferred. Further, the filter medium constituting the raw material filter may be any of metal wind, laminated metal mesh, metal nonwoven fabric, porous metal plate, etc., but from the viewpoint of filtration accuracy, a laminated metal mesh or metal nonwoven fabric is preferable, among which metal A type in which a nonwoven fabric is sintered and fixed is preferable.

  There are no particular restrictions on the material of the raw material filter, and metals, resins, ceramics, etc. can be used. From the viewpoint of durability, heat resistance, ease of handling, and color reduction, iron can be used. A metal filter having a content of 80% by weight or less is preferable, and stainless steel such as SUS304, SUS316, SUS316L, and SUS310S is particularly preferable.

Further, in order to extend the life of the raw material filtration filter while ensuring the filtration performance during the filtration of the raw material monomer, it is preferable to use a plurality of filter units, and in particular, the filter eyes in the upstream unit. In the case where the opening is C μm and the opening of the filter in the downstream unit is D μm, in at least one combination, C is preferably larger than D (C> D). When this condition is satisfied, the raw material filtration filter is less likely to be blocked, and the replacement frequency of the raw material filtration filter can be reduced.

  The opening of the raw material filtration filter is not particularly limited, but in at least one of the raw material filtration filters, the filtration accuracy of 99.9% is preferably 10 μm or less, and the filter unit constituting the raw material filtration filter includes In the case of a plurality of arrangements, it is preferably 8 μm or more, more preferably 10 μm or more on the most upstream side, and preferably 2 μm or less, more preferably 1 μm or less on the most downstream side. In addition, the opening of the said raw material filtration filter said here is determined based on ISO16889.

In the present invention, the temperature of the raw material fluid when the raw material is passed through the raw material filtration filter is not limited. However, if the raw material is too low, the raw material is solidified. If the raw material is too high, there is a problem such as thermal decomposition. ° C, preferably 100 ° C to 150 ° C.
In the present invention, any of the raw materials to be used may be filtered, or all of the raw materials may be filtered. The method is not limited, and the dihydroxy compound and the carbonic acid diester are not limited. The raw material mixture may be filtered, or may be mixed after separately filtering. Moreover, in the manufacturing method of this invention, the reaction liquid in the middle of a polycondensation reaction can also be filtered with the filter similar to the said raw material filtration filter.

  In the present invention, as described above, when a polycarbonate resin is produced by polycondensation of a dihydroxy compound containing the above formulas (1) and (2) and a carbonic acid diester by a transesterification reaction, Also referred to as “catalyst” or “polycondensation catalyst”).

  In the present invention, the catalyst can affect the thermal stability of the polycarbonate resin and the yellowness index (YI) value representing the hue. The catalyst used is not limited as long as it satisfies the thermal stability and hue of the polycarbonate resin. However, the catalyst is not limited to Group 1 or Group 2 in the long-period periodic table (hereinafter simply referred to as “Group 1”). And a basic compound such as a metal compound, a basic boron compound, a basic phosphorus compound, a basic ammonium compound, and an amine compound. Preferably, Group 1 metal compounds and / or Group 2 metal compounds are used. More preferably, it is a metal compound of a metal selected from the group consisting of a long-period group 2 metal and lithium.

  The group 1 metal compound and / or group 2 metal compound is usually used in the form of a hydroxide or a salt such as a carbonate, carboxylate, or phenol salt. From the viewpoint of easiness, hydroxide, carbonate and acetate are preferable, and acetate is preferable from the viewpoint of hue and polycondensation activity.

Specific examples of the group 1 metal compound include sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, cesium hydrogen carbonate, sodium carbonate, and carbonic acid. Potassium, lithium carbonate, cesium carbonate, sodium acetate, potassium acetate, lithium acetate, cesium acetate, sodium stearate, potassium stearate, lithium stearate, cesium stearate, sodium borohydride, potassium borohydride, lithium borohydride Cesium borohydride, sodium borohydride, potassium borohydride, lithium phenyl borohydride, cesium phenyl borohydride, sodium benzoate, potassium benzoate, lithium benzoate, cesium benzoate, phosphorus 2 sodium hydrogen, 2 potassium hydrogen phosphate, 2 lithium hydrogen phosphate, 2 cesium hydrogen phosphate, 2 sodium phenyl phosphate, 2 potassium phenyl phosphate, 2 lithium phenyl phosphate, 2 cesium phenyl phosphate, sodium, potassium, Examples thereof include lithium, cesium alcoholate, phenolate, bisphenol A disodium salt, 2 potassium salt, 2 lithium salt, 2 cesium salt, etc. Among them, lithium compounds are preferred.

  Specific examples of the Group 2 metal compound include 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, calcium acetate, barium acetate, magnesium acetate, strontium acetate, calcium stearate, barium stearate, magnesium stearate, strontium stearate, and the like. From the viewpoint of hue, among them, a magnesium compound, a calcium compound, and a barium compound are preferable.

  In addition, a basic compound such as a basic boron compound, a basic phosphorus compound, a basic ammonium compound, and an amine compound can be used in combination with the aforementioned Group 1 metal compound and / or Group 2 metal compound. However, since it may volatilize during the polycondensation reaction and cause trouble, it is particularly preferable to use only the Group 1 metal compound and / or the Group 2 metal compound.

  Examples of the basic boron compound that can be used in combination include tetramethylboron, tetraethylboron, tetrapropylboron, tetrabutylboron, trimethylethylboron, trimethylbenzylboron, trimethylphenylboron, triethylmethylboron, triethylbenzylboron, and triethyl. Sodium salt, potassium salt, lithium salt, calcium salt, barium salt, magnesium salt, such as phenyl boron, tributyl benzyl boron, tributyl phenyl boron, tetraphenyl boron, benzyl triphenyl boron, methyl triphenyl boron, butyl triphenyl boron, or Examples include strontium salts.

  Examples of the basic phosphorus compound that can be used in combination include triethylphosphine, tri-n-propylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, tributylphosphine, or a quaternary phosphonium salt. It is done.

  Examples of the basic ammonium compound that can be used in combination include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethylethylammonium hydroxide, trimethylbenzylammonium hydroxide, and trimethyl. Phenylammonium hydroxide, triethylmethylammonium hydroxide, triethylbenzylammonium hydroxide, triethylphenylammonium hydroxide, tributylbenzylammonium hydroxide, tributylphenylammonium hydroxide, tetraphenylammonium hydroxide, benzyltriphenylammonium hydroxide, methyltrimethyl Phenyla Mode onium hydroxide, butyl triphenyl ammonium hydroxide, and the like.

  Examples of the amine compound that can be used in combination include 4-aminopyridine, 2-aminopyridine, N, N-dimethyl-4-aminopyridine, 4-diethylaminopyridine, 2-hydroxypyridine, 2-methoxypyridine, 4 -Methoxypyridine, 2-dimethylaminoimidazole, 2-methoxyimidazole, imidazole, 2-mercaptoimidazole, 2-methylimidazole, aminoquinoline and the like.

  The amount of the catalyst used is preferably 0.1 μmol to 500 μmol, preferably 0.5 μmol to 300 μmol, more preferably 0.5 μmol to 200 μmol, still more preferably 0.5 μmol to 100 μmol, per 1 mol of all dihydroxy compounds used. Especially preferably, it is 1 micromol-50 micromol. Among them, when using at least one metal compound selected from the metals of Group 2 of the long-period periodic table and lithium, the amount of metal is usually 0.1 μmol or more, preferably 1 μmol or more, per 1 mol of all dihydroxy compounds used. Particularly preferably, it is 10 μmol or more. Further, the upper limit is usually 500 μmol, preferably 300 μmol, more preferably 200 μmol, particularly preferably 100 μmol, and particularly preferably 50 μmol.

  If the amount of the catalyst used is too small, the polycondensation reaction will not proceed easily, and a polycarbonate resin having a desired molecular weight may not be obtained. On the other hand, if the amount of the catalyst used is too large, the hue of the polycarbonate resin obtained by an undesired side reaction may be deteriorated or foreign matter may be caused. The amount of metal in the polycarbonate resin can be measured using a method such as atomic emission, atomic absorption, Inductively Coupled Plasma (ICP) after recovering the metal in the polycarbonate resin by a method such as wet ashing. I can do it.

  In the method of the present invention, the method of obtaining a polycarbonate resin by polycondensation of the dihydroxy compound and the carbonic acid diester may be carried out in multiple stages using a plurality of reaction vessels in the presence of the catalyst. The type of reaction may be any of batch type, continuous type, or a combination of batch type and continuous type. Among these, the continuous type is preferable from the viewpoint of stabilizing the quality. In the initial stage of polycondensation, it is preferable to obtain a prepolymer at a relatively low temperature and low vacuum, and in the latter stage of polycondensation, it is preferable to increase the molecular weight to a predetermined value at a relatively high temperature and high vacuum. It is important from the viewpoint of hue and thermal stability to appropriately select the jacket temperature and internal temperature, and the pressure in the reaction system. For example, if either the temperature or the pressure is changed too quickly before the polycondensation reaction reaches a predetermined value, the unreacted monomer will be distilled, causing the molar ratio of the dihydroxy compound and the carbonic acid diester to change, and the polycondensation rate Or a polymer having a predetermined molecular weight or terminal group cannot be obtained, and as a result, the object of the present invention may not be achieved.

  Furthermore, it is effective to use a reflux condenser in the polycondensation reaction tank in order to suppress the amount of unreacted monomer (dihydroxy compound or carbonic acid diester) that is distilled off. The effect is great in this reaction tank. The temperature of the refrigerant introduced into the reflux condenser can be appropriately selected according to the monomer used, but the temperature of the refrigerant introduced into the reflux condenser is usually 45 to 180 ° C. at the inlet of the reflux condenser. Yes, preferably 80 to 150 ° C, particularly preferably 100 to 140 ° C. If the temperature of the refrigerant is too high, the amount of reflux decreases and the effect is reduced. On the other hand, if the temperature is too low, the distillation efficiency of the monohydroxy compound that should be distilled off tends to decrease. As the refrigerant, hot water, steam, heat medium oil or the like is used, and steam or heat medium oil is preferable.

  In order to maintain the speed of the polycondensation reaction appropriately, suppress the distillation of the monomer, suppress the occurrence of foreign matter in the final polycarbonate resin, and prevent the hue and thermal stability from being impaired. The selection of the type and amount of catalyst is important. If the catalyst activity is low or the amount is low, the amount of unreacted monomer is large and the pressure is exposed to a low pressure. It may collapse and the polycondensation reaction may stop. When the amount of the catalyst is large, as described above, there is a possibility that the thermal stability of the obtained polycarbonate resin is lowered and the hue is deteriorated.

In the present invention, the catalyst is preferably used for polycondensation in multiple stages using a plurality of reaction vessels. The reason for carrying out polycondensation in a plurality of reaction vessels is that at the initial stage of the polycondensation reaction, the amount of monomer contained in the reaction solution is large, so that the volatilization of the monomer can be suppressed while maintaining the necessary polycondensation rate. In the latter stage of the polycondensation reaction, in order to shift the equilibrium to the polymer production side, it is important to sufficiently distill off the by-produced monohydroxy compound, and desirable polycondensation reaction conditions differ between the initial stage and the later stage. Because. Thus, in order to set different polycondensation reaction conditions, it is preferable from the viewpoint of production efficiency to use a plurality of polycondensation reaction tanks arranged in series.

  As described above, the reaction tank used in the polycondensation in the present invention may be at least two or more, but from the viewpoint of production efficiency, etc., three or more, preferably 3 to 5, particularly Preferably, there are four. In the present invention, if there are two or more reaction vessels, different reaction conditions can be set in each reaction vessel, and the temperature and pressure are continuously changed in each reaction vessel. May be.

In the present invention, the polycondensation catalyst can be added to the raw material preparation tank and the raw material storage tank, or can be added directly to the polycondensation reaction tank, but from the viewpoint of supply stability and control of polycondensation. The catalyst supply pipe may be installed in the middle of the raw material pipe before being supplied to the polycondensation reaction tank, and preferably supplied as an aqueous solution.
If the temperature of the polycondensation reaction is too low, it causes a decrease in productivity and an increase in the thermal history of the product, and if it is too high, it not only causes evaporation of the monomer, but also may promote decomposition and coloring of the polycarbonate resin. is there.

  The specific temperature is as follows. In the first stage reaction, the maximum internal temperature of the polycondensation reaction tank is preferably 130 to 270 ° C, preferably 160 to 250 ° C, more preferably 180 to 230 ° C, and preferably 110 to 1 kPa, preferably Is 70 to 5 kPa, more preferably 30 to 10 kPa (absolute pressure) for 0.1 to 10 hours, preferably 0.5 to 3 hours, while distilling off the by-produced monohydroxy compound out of the reaction system. To be implemented. The reaction in the first stage in the present invention is the reaction in the reaction tank in the uppermost stream of the process in the reaction tank in which 5% by weight or more of the monohydroxy compound distilled through the entire polycondensation reaction is distilled. Point to.

  In the second and subsequent stages, the pressure in the reaction system is gradually reduced from the pressure in the first stage, and the monohydroxy compound that is subsequently generated is removed from the reaction system. 5 kPa or less, preferably 3 kPa or less, particularly preferably 1 kPa or less, 210 ° C. or higher, preferably 220 ° C. or higher, 290 ° C. or lower, preferably 280 ° C. or lower, more preferably 270 ° C. or lower, usually 0.1 to 10 Time, preferably 1 to 6 hours, particularly preferably 0.5 to 3 hours.

  In particular, in order to suppress the coloring and thermal deterioration of the polycarbonate resin and obtain a polycarbonate resin having a good hue and thermal stability, the maximum internal temperature in all reaction stages is 280 ° C. or lower, preferably 270 ° C. or lower. preferable. The internal temperature here indicates the temperature of the process liquid, and is usually measured by a thermometer using a thermocouple or the like provided in the reaction vessel. In addition, in order to suppress the decrease in the polycondensation rate after the polycondensation reaction and minimize deterioration due to thermal history, a horizontal reaction tank with excellent plug flow and interface renewability is used at the final stage of polycondensation. It is preferable to do. If the polycondensation temperature is increased and the polycondensation time is made too long in order to obtain a polycarbonate resin having a predetermined molecular weight, the yellowness index (YI) value representing the hue tends to increase.

The monohydroxy compound distilled off as a by-product in the reaction is preferably used as a raw material for fuels and chemicals from the viewpoint of effective utilization of resources. In particular, after purification as necessary, it is preferably reused as a raw material for carbonic acid diesters, bisphenol compounds and the like.
In the method for producing a polycarbonate resin of the present invention, after the above polycondensation reaction is performed, the polycarbonate resin obtained using a filter having a filter medium made of a metal nonwoven fabric is filtered. In particular, the polycarbonate resin obtained by polycondensation is introduced into the extruder and then discharged from the extruder in order to simultaneously remove the low molecular weight components contained in the polycarbonate resin and add and knead the heat stabilizer and the like. It is preferable to filter the resin using the filter.

Examples of the method for filtering the polycarbonate resin obtained by polycondensation as described above using the filter include the following methods.
In order to generate the pressure necessary for filtration, a polycarbonate resin is extracted from the final polycondensation reaction tank in a molten state using a gear pump or a screw, and filtered through the filter; A method in which polycarbonate resin is supplied to a twin-screw extruder, melt extruded, filtered through the filter, cooled and solidified in the form of a strand, and pelletized with a rotary cutter, etc .; solidified from the final polycondensation reaction tank The polycarbonate resin is supplied to a single-screw or twin-screw extruder in a molten state without being melted, melt-extruded, once cooled and solidified in the form of a strand, pelletized, the pellet is introduced again into the extruder, and the filter Filtered through, cooled and solidified in the form of strands, and pelletized;

Alternatively, the polycarbonate resin is extracted from the final polycondensation reaction tank in a molten state, cooled and solidified in the form of a strand without passing through an extruder, and once pelletized, then the pellets are supplied to a single or twin screw extruder, After melt extrusion, the mixture is filtered through the filter, cooled and solidified in the form of strands, and pelletized.
Above all, to minimize thermal history, suppress thermal deterioration such as deterioration of hue and molecular weight, and prevent contamination by foreign substances from the outside, it is uniaxial in the molten state without solidifying from the final polycondensation reaction tank. Alternatively, after supplying resin to a twin-screw extruder and melt-extruding it, it is supplied to the filter using a gear pump, filtered, discharged from a die, cooled and solidified in the form of a strand, and pelletized with a rotary cutter, etc. Is preferred.

  Although the form of the extruder is not limited, a single-screw or twin-screw extruder is used. Among them, a twin screw extruder is preferable for improving the devolatilization performance described later and for uniform kneading of the additive. In this case, the rotation direction of the shaft may be different or the same, but the same direction is preferable from the viewpoint of kneading performance. Use of an extruder can stabilize the supply of polycarbonate resin to the filter.

In addition, in the polycarbonate resin obtained by polycondensation as described above, hue, heat stability, raw material monomers that may adversely affect the product due to bleed-out, etc. Low molecular weight compounds such as hydroxy compounds and polycarbonate oligomers often remain, but those having a vent port as the extruder are preferably used by reducing the pressure from the vent port using a vacuum pump or the like. It is also possible to devolatilize and remove. Moreover, volatile liquids, such as water, can be introduce | transduced in the said extruder, and devolatilization can also be accelerated | stimulated. The number of vent ports may be one or plural, but preferably two or more.
Furthermore, additives such as a thermal stabilizer, a release agent, and a colorant, which will be described later, can be kneaded using the extruder.

The structure derived from the dihydroxy compound represented by the above formula (1) in the polycarbonate resin of the present invention is poor in thermal stability and easily changes to a foreign substance called gel or burn when the temperature is high. In particular, even when the temperature of the entire polycarbonate resin is low, if heat is applied locally, gel or burns are selectively generated in that part, eventually deteriorating the overall quality of the polycarbonate resin, In order to reduce the commercial value, it is important to suppress local heating of the polycarbonate resin in the extruder. In order to suppress the generation of such gels and burns, and to suppress the decrease in molecular weight and hue due to thermal decomposition, the peripheral speed of a shaft (hereinafter sometimes referred to as a screw) provided in the extruder is usually 1 0.0 m / sec or less, preferably 0.6 m / sec or less, particularly preferably 0.4 m / sec or less. On the other hand, if the peripheral speed becomes too low, venting up during vacuum devolatilization tends to occur, and devolatilization performance and additive dispersion performance tend to be lowered. Therefore, usually 0.05 m / second or more, preferably It is 0.1 m / second or more. When the peripheral speed of the screw exceeds the above range, the shear heat generation of the polycarbonate resin increases, and local heat generation occurs in a constricted portion where the distance between the screw and the barrel is close, leading to generation of the gel and burns, It tends to cause a decrease in molecular weight and a deterioration in hue due to decomposition. On the other hand, if the peripheral speed of the screw is too small, the devolatilization performance may deteriorate and the additive kneading performance may deteriorate. Extrusion (bent-up) of the resin tends to occur, causing gel and burns.

  Usually, the screw of an extruder is composed of a plurality of elements (screw elements) in order to give various functions, and generally only a spiral screw (flight) mainly for the purpose of transporting resin. Consists of full flight, kneading disc for resin kneading, seal ring for resin sealing, etc., depending on the purpose, reverse flight or reverse flight with screws arranged in the direction opposite to the resin transport direction A kneading disc is also used. There are two- and three-row types depending on how the screw is cut. In the present invention, a double-row type deep groove type that can take a large amount of processing with respect to the screw diameter of the extruder and can suppress shearing heat generated by screw rotation. Is preferred.

  In the present invention, the configuration of these screw elements is not limited, but it is preferable to have a kneading disk. Among them, the total length of the kneading disk is 20% of the total length of the screw. % Or less, more preferably 15% or less, and most preferably 10% or less. If the total length of the kneading disk is too long, local heat generation due to the shearing of the resin increases, and problems such as deterioration of the hue and molecular weight of the polycarbonate resin tend to occur. On the other hand, if the total length of the kneading disk is too short, the performance at the time of devolatilization and kneading of the additive may be deteriorated. It is preferably 3% or more of the length, and more preferably 5% or more.

The kneading disk includes a forward feed type, an orthogonal type, and a reverse feed type with respect to the resin transport direction, and can be appropriately selected according to the viscosity of the resin used and the required performance.
As the material of the screw element, it is preferable to increase the surface nickel content or the like to keep the iron content low, or to treat the surface hardness with TiN or CrN.

In the present invention, when the weight of the resin extruded per hour by the extruder is W (kg / h) and the sectional area of the barrel of the extruder is S (m ² ), the following formula (7) is satisfied. It is preferable to satisfy.
12000 ≦ W / S ≦ 60000 (7)
If W / S is too small, not only will the size of the extruder be excessive with respect to the amount of polycarbonate resin to be processed, but also the residence time in the extruder will increase, reducing the molecular weight of the polycarbonate resin and deterioration such as coloring. The lower limit is preferably 15000, more preferably 20000, and particularly preferably 25000, since it may cause gelation or generation of gel or burn. On the other hand, if it is too large, an excessive amount of polycarbonate resin will be supplied with respect to the size of the extruder, which may lead to a decrease in devolatilization efficiency, deterioration of polycarbonate resin due to shearing heat generation, and generation of gel and burns. Is preferably 50000, more preferably 40000, and particularly preferably 35000.

  In the present invention, the temperature of the resin when the polycarbonate resin is supplied in the molten state to the extruder is preferably 200 ° C. or higher, and particularly preferably 210 ° C. or higher, particularly 220 ° C. or higher. Further, the upper limit is preferably 300 ° C. or less, more preferably 290 ° C. or less, and particularly preferably 280 ° C. or less. If the temperature of the polycarbonate resin supplied to the extruder is too low, the melt viscosity of the polycarbonate resin becomes too high and the supply becomes unstable, or the load of the drive motor of the extruder becomes excessive, and the equation (7) In addition to the possibility of not being able to satisfy, there is a possibility that shear heat generation in the extruder becomes large, which causes deterioration of the polycarbonate resin and generation of gel or burns. On the other hand, when the temperature is too high, the polycarbonate resin is likely to be deteriorated, and there is a tendency that the hue is deteriorated, the molecular weight is decreased, and gel or burn is generated.

The temperature of the polycarbonate resin supplied to the extruder is controlled by controlling the internal temperature of the final polycondensation reaction tank, controlling the temperature of the piping for supplying the polycarbonate resin to the extruder, or providing a heat exchanger. Can be controlled.
In the present invention, the temperature of the polycarbonate resin discharged from the extruder and supplied to the filter is usually 300 ° C. or lower, preferably 290 ° C. or lower, more preferably 280 ° C. or lower. When the temperature of the polycarbonate resin discharged from the extruder becomes too high, the polycarbonate resin is likely to be deteriorated, and there is a tendency that the hue is deteriorated, the molecular weight is decreased, and gel and burn are generated. Conversely, if the temperature of the polycarbonate resin discharged from the extruder becomes too low, the melt viscosity of the polycarbonate resin is high, the load on the extruder increases, screw rotation becomes unstable, and the motor is overloaded. In addition, the pressure loss before and after the filter may become too large, so that the temperature is preferably 220 ° C. or higher, more preferably 230 ° C. or higher, and particularly preferably 240 ° C. or higher. Usually, in an extruder, heat is generated by shearing of the resin accompanying the rotation of the screw, and generally the temperature of the discharged polycarbonate resin tends to be higher than the temperature of the supplied polycarbonate resin. This tendency becomes significant when the molecular weight is high and the melt viscosity is high. Increasing the temperature of the polycarbonate resin tends to lower the melt viscosity, and the shear heat generation tends to be suppressed.However, the higher the temperature of the polycarbonate resin, the more likely it is to deteriorate, and the deterioration of the hue, molecular weight, gel, Since there is a tendency to cause burns, it is not easy to perform extrusion or filtration by preventing deterioration of a high-viscosity polycarbonate resin having poor thermal stability.

The temperature of the polycarbonate resin discharged from the extruder and supplied to the filter in the present invention refers to a temperature measured by attaching a thermometer between the extruder and the filter unit, preferably a filter unit unit described later.
The temperature of the polycarbonate resin discharged from the extruder is usually controlled by the temperature of the supplied polycarbonate resin or the temperature of a heater attached to a barrel (also referred to as a cylinder). Since it may vary depending on the supply amount to the machine and the screw rotation speed of the extruder, it is preferable to control these conditions together.

The barrel of the extruder is usually provided with a plurality of attached heaters, and the temperature can be set independently. In the present invention, at least one heater set temperature is preferably 270 ° C. or less, more preferably 260 ° C. or less. More preferably, it is 240 ° C. or less, particularly preferably 220 ° C. or less. By setting the heater in this way, when the resin is heated to a temperature higher than that, it is cooled there, and the polycarbonate resin is prevented from being deteriorated by heat. Although the present invention can be implemented even if a part of the heater exceeds the upper limit of the above temperature, it is more preferable that all the heaters are 270 ° C. or lower in order to prevent overheating more thoroughly.

  On the other hand, the heater set to 270 ° C. or lower for the purpose of preventing overheating is preferably at least 100 ° C. or higher. If there is a part that is too cold in the barrel of the extruder, the polycarbonate resin is rapidly cooled at the part where it comes into contact with the barrel, the viscosity increases, and the shear heat generation increases, which in turn accelerates the deterioration of the polycarbonate resin or rotates the screw. The motor load may increase. The set temperature of the heater is more preferably 120 ° C. or higher, further preferably 140 ° C. or higher, and particularly preferably 160 ° C. or higher.

Due to shear heat generation in the extruder, the resin tends to become hot as it approaches the outlet. For this reason, it is preferable that a low temperature part exists in an exit side more. That is, it is preferable that each heater has the same or lower set temperature as the adjacent heater on the polycarbonate resin supply side in at least one combination.
However, since the viscosity of the polycarbonate resin increases and may cause local overheating if it is excessively cooled, the temperature difference with respect to the heater adjacent to the supply side is preferably 50 ° C. or less.

Especially in the case of polycarbonate resin with high viscosity, shear heat generation due to screw rotation increases, and the temperature of the discharged resin tends to rise with respect to the temperature of the supplied resin. Therefore, dispersion of additives, devolatilization performance, and productivity In order to suppress the deterioration of the polycarbonate resin due to the shear heat generation while maintaining the above, it is important to select the number of rotations of the screw, the peripheral speed, and the element configuration.
In this invention, in order to remove foreign materials, such as a burn and gel in the polycarbonate resin obtained by polycondensation, it filters with a filter. Among them, in order to remove residual monomers, by-product phenol, etc. by vacuum devolatilization, and to mix additives such as heat stabilizers and mold release agents, the polycarbonate resin of the present invention is extruded with an extruder and then filtered with a filter. It is preferable to do.

  As the form of the filter, known ones such as a candle type, a pleat type, a leaf disk type can be used. Among them, a leaf disk type that can take a large filtration area with respect to the storage container of the filter is preferable, and a large filtration area can be taken. Thus, it is preferable to use a combination of a plurality of filters. The filter in the present invention means a filter that is configured by combining a holding member (hereinafter also referred to as a retainer) and a filter medium (hereinafter also referred to as a filtration member or a medium). In order to increase the filtration area at the same time, and to facilitate replacement when the filter is closed, in the form of a unit (also referred to as a filter unit) stored in a storage container in the form of a plurality or a plurality of the filters arranged side by side It is preferable to use it. In particular, in the case of continuous filtration for a long time, it is preferable from the viewpoint of improving production efficiency and operating stability that a plurality of filter units are arranged and switched according to the blocking condition.

  In the present invention, the media of the filter needs to be a metal nonwoven fabric in which metal fiber felts are laminated. In a commonly used mesh type filter, even if a plurality of meshes are combined, the polycarbonate of the present invention is used. It is difficult to remove foreign matters such as gels and burns contained in the resin to a level that can be used for optical applications. In particular, it is preferable to sinter and fix steel wires constituting the nonwoven fabric in order to suppress slipping of gels and the like.

  In the present invention, it is preferable that a plurality of aperture media be overlapped so that the differential pressure (pressure loss) of the filter is reduced, and the apertures become finer in order from the resin intrusion direction. It is also possible to use a sintered metal powder for the purpose of crushing the gel.

  In the present invention, the aperture of the filter is preferably not more than 50 μm, more preferably not more than 30 μm, still more preferably not more than 20 μm, and preferably not more than 15 μm in order to reduce foreign matters. If the opening is reduced, the pressure loss in the filter increases, and the filter may be damaged or the polycarbonate resin may be deteriorated by shearing heat generation. Therefore, the filtration accuracy of 99% is 1 μm or more. It is preferable. Here, the aperture defined as 99% filtration accuracy refers to the value of χ when the βχ value represented by the following formula (12) determined in accordance with ISO 16889 is 100.

βχ = (number of particles on the primary side larger than χ μm) / (number of particles on the secondary side larger than χ μm) (12)
(Here, the primary side is before filtration with a filter, and the secondary side is after filtration.)

  The transition metal on the surface of the filter retainer and the media, especially the iron component, may promote the deterioration of the polycarbonate resin of the present invention and the formation of gels and burns during filtration at a high temperature exceeding 200 ° C. In the present invention, heat treatment is performed at a temperature of 330 ° C. to 600 ° C. before use. This heat treatment makes it possible to passivate the surface. The temperature of the heat treatment is preferably 350 ° C. or higher and 550 ° C. or lower, more preferably 350 ° C. or higher and 500 ° C. or lower, and particularly preferably 350 ° C. or higher and 450 ° C. or lower. The heat treatment time is usually 3 hours to 200 hours, preferably 5 hours to 100 hours. If the temperature of the heat treatment is too low or the time is too short, the formation of the passive state becomes insufficient, and the filtration of the polycarbonate resin of the present invention and the formation of gels and burns may be promoted during filtration. On the other hand, if the temperature of the heat treatment is too high or the time is too long, the filter media may be severely damaged, and the required filtration accuracy may not be achieved. By applying the production method of the present invention, a general stainless steel material such as SUS304 or SUS316 is used without using a filter made of a material with extremely low Fe content, and a polycarbonate resin with reduced foreign matter and coloring is obtained. Can be obtained.

  The heat treatment is preferably performed in the presence of water vapor and / or oxygen (hereinafter sometimes referred to as roasting treatment) in order to form an oxide film. The temperature for performing the roasting treatment needs to be 330 ° C. or higher and 600 ° C. or lower, preferably 350 ° C. or higher and 550 ° C. or lower, more preferably 350 ° C. or higher and 500 ° C. or lower, and particularly preferably 350 ° C. or higher and 450 ° C. or lower. It is as follows. The roasting time is usually 3 hours to 200 hours, preferably 5 hours to 100 hours. If the temperature of the roasting treatment is too low or the time is too short, the formation of the passive state becomes insufficient, and the filtration of the polycarbonate resin of the present invention and the formation of gels and burns may be promoted during filtration. On the other hand, if the temperature of the roasting process is too high or the time is too long, the filter media is seriously damaged, and the necessary filtration accuracy may not be obtained.

  In order to passivate the surface of the filter retainer and the media, in addition to the heat treatment, a treatment method with an acid in which the filter is immersed in an acid such as sulfuric acid or nitric acid, or an acid is passed through the filter may be mentioned. It is done. In the present invention, it is preferable to use a combination of passivating by heat treatment and passivating by treatment with acid. The acid used for the treatment with acid is preferably an inorganic acid, and more preferably nitric acid. In particular, it is preferable to perform both the treatment with nitric acid and the roasting treatment.

The concentration of nitric acid when the filter is treated with nitric acid is usually 5% to 50% by weight, preferably 10% to 30% by weight, and the temperature during treatment is usually 5 ° C to 100 ° C, preferably 50 ° C. -90 degreeC and processing time are 5 minutes-120 minutes normally, Preferably they are 10 minutes-60 minutes. If the concentration of nitric acid is too low, the processing temperature is too low, or the processing time is too short, the formation of passives will be insufficient, the concentration of nitric acid will be too high, the processing temperature will be too high, or the processing time will be If it is too long, the filter media will be severely damaged and the required filtration accuracy may not be achieved.

  It is preferable that the filter is stored in a storage container because it facilitates filtration under pressure while securing a necessary filtration area. The material of the containment vessel is not limited as long as it has strength and heat resistance that can withstand resin filtration, but is preferably a stainless steel such as SUS316 or SUS316L with a low iron content. When the iron content is large, the polycarbonate resin of the present invention may be deteriorated and the formation of gels and burns may be promoted as described above.

  The storage container of the filter may be arranged such that the supply port and the discharge port of polycarbonate resin are arranged substantially horizontally, arranged substantially vertically, or arranged obliquely. In order to prevent gas and polycarbonate resin from staying in the container and prevent deterioration of the polycarbonate resin, it is preferable that the supply port of the polycarbonate resin is disposed at the lower part of the filter storage container and the discharge port is disposed at the upper part.

Moreover, if the value obtained by dividing the internal volume (m ³ ) of the filter storage container by the polycarbonate resin flow rate (m ³ / min) is too small, the differential pressure of the filter may increase and the filter may be damaged. If it is too large, deterioration of the polycarbonate resin and the formation of gel and burns may be promoted during filtration, so 1 to 20 minutes is preferable, preferably 2 to 10 minutes, more preferably 3 to 8 minutes, particularly preferably. Is 3-6 minutes.

  In this invention, it is preferable that the linear velocity of the molten resin in the said filter surface is 0.01-0.5 m / h. The linear velocity of the molten resin on the filter surface can be determined by dividing the processing volume of polycarbonate resin per hour by the filtration area of the filter. If this linear velocity is excessively low, the residence time during filtration may become long, which may promote the deterioration of the polycarbonate resin and the formation of gels and burns. If it is excessively large, shear heat generation during filtration will increase and coloring will occur. Since it may cause generation of foreign matters such as gel, gel and burn, it is preferably 0.03 to 0.3 m / h, particularly preferably 0.05 to 0.15 m / h.

  In the method of the present invention, the temperature of the polycarbonate resin supplied to the filter is usually 300 ° C. or lower, preferably 290 ° C. or lower, particularly 280 ° C. or lower, particularly 270 ° C. or lower. If the temperature before filtering with the filter becomes too high, thermal deterioration in the filter unit tends to occur, and there is a tendency to cause deterioration in hue, molecular weight, and mechanical strength. Conversely, if the temperature before filtering with the filter becomes too low, the polycarbonate has a high melt viscosity, and the load on the filter increases and may cause damage to the filter. Above, more preferably 230 ° C or higher, particularly preferably 240 ° C or higher.

  In the present invention, the temperature of the polycarbonate resin after filtration is preferably 200 ° C. or higher, more preferably 220 ° C. or higher, and further preferably 230 ° C. or higher. If the temperature of the polycarbonate resin after filtration using the filter is too low, the melt viscosity becomes high and the extruded strands are not stable and tend to be difficult to be pelletized with a rotary cutter or the like. There is. On the other hand, the resin temperature after filtration is preferably 300 ° C. or lower, more preferably 290 ° C. or lower, still more preferably 280 ° C. or lower, and particularly preferably 270 ° C. or lower. If the temperature of the polycarbonate resin after filtration using the filter is too high, the polycarbonate resin is likely to be thermally deteriorated, which tends to cause a deterioration in hue, a decrease in molecular weight, and a decrease in mechanical strength associated therewith.

The resin temperature after filtration can be measured by a method in which the resin discharged from the filter is taken out and directly measured, a method in which a sensor is installed inside the pipe of the filter outlet channel, or the like.
When a sensor is installed inside the pipe of the filter outlet channel, it is sometimes difficult to measure the correct resin temperature due to the influence of a heater installed outside the pipe around the sensor. If a device that discharges resin such as a die is installed near the filter outlet and the temperature of the resin discharged from the device can be regarded as equivalent to the resin temperature on the filter outlet side, The temperature of the discharged resin may be the resin temperature after filtration according to the present invention.

For the purpose of increasing the accuracy of the resin temperature after filtration, a sensor is installed inside the pipe of the filter outlet channel, and the temperature of the resin discharged from a die installed near the filter outlet is measured. Both methods can also be implemented.
In the method of the present invention, the filter unit is usually provided with a heater composed of a plurality of blocks outside thereof to control the temperature. However, if the set temperature is too high, the polycarbonate resin may be deteriorated. In the following, it is preferably set to 270 ° C. or lower, particularly preferably 260 ° C. or lower. On the other hand, if the set temperature is too low, the melt viscosity becomes high and it is difficult to filter with a filter, so that the temperature is usually 150 ° C. or higher, preferably 180 ° C. or higher, particularly preferably 200 ° C. or higher.

  Also, the piping for guiding the polycarbonate resin discharged from the filter unit to the die is usually provided with a heater outside, but if the set temperature is too high, the polycarbonate resin may be deteriorated. In the following, it is preferably set to 270 ° C. or lower, particularly preferably 260 ° C. or lower. On the other hand, if the set temperature is too low, the melt viscosity becomes high and the pressure loss in the pipe increases, so that the temperature is usually 150 ° C. or higher, preferably 180 ° C. or higher, particularly preferably 200 ° C. or higher. Furthermore, if the residence time of the polycarbonate resin from the outlet of the filter unit to the die is long, the polycarbonate resin may be deteriorated. Therefore, the time is usually 1 to 30 minutes, preferably 3 to 20 minutes.

  In the method of the present invention, the temperature of the polycarbonate resin discharged from the die through filtration with the filter is preferably 200 ° C or higher, preferably 220 ° C or higher, more preferably 230 ° C or higher, and the upper limit is usually 300 ° C. 280 ° C. or lower, preferably 270 ° C. or lower, more preferably 265 ° C. or lower. If the temperature of the polycarbonate resin discharged from the die after filtration is too low, the melt viscosity becomes high and the extruded strands are not stable and may be difficult to pelletize with a rotary cutter or the like There is sex. On the other hand, if the temperature is too high, the polycarbonate resin is likely to be thermally deteriorated, which may cause a deterioration in hue, a decrease in molecular weight, and a decrease in mechanical strength associated therewith.

  The die is usually provided with a heater, but if the set temperature is too high, the polycarbonate resin may be deteriorated. Therefore, the die is usually set to 280 ° C. or lower, preferably 270 ° C. or lower, particularly preferably 260 ° C. or lower. . On the other hand, if the set temperature is too low, the melt viscosity becomes high and the pressure loss in the pipe increases, so that the temperature is usually 150 ° C. or higher, preferably 180 ° C. or higher, particularly preferably 200 ° C. or higher.

Normally, when polycarbonate resin is filtered through the above-mentioned filter having a small mesh opening, the temperature rises due to shearing heat generation, and when using an extruder, shearing heat generation due to screw rotation is also added, so the polycarbonate discharged from the die through filtration To control the temperature of the resin, it is important to comprehensively control the opening of the filter, the filtration area, the temperature setting, the molecular weight of the polycarbonate resin, the temperature setting of the filter unit, the temperature setting from the filter outlet to the die, etc. become. In addition, when using the extruder for supplying to the filter, it is important to select the processing amount of polycarbonate resin in the extruder, the rotational speed and peripheral speed of the screw, the element configuration, etc. as described above. become. In particular, the structure derived from the dihydroxy compound represented by the formula (1) tends to start to decompose at low temperatures, and when trying to satisfy the quality used for optical applications so that the polycarbonate resin does not decompose, In addition to the selection of the filter, these comprehensive controls are important.

  In the method of the present invention, the difference between the temperature of the polycarbonate resin before being filtered by the filter and the temperature of the polycarbonate resin after the filtration is preferably within 50 ° C, more preferably within 30 ° C, most preferably Preferably it is within 10 degreeC. When the temperature difference between the temperature of the polycarbonate resin before being filtered by the filter and the temperature of the polycarbonate resin after the filtration becomes too large, particularly when a filter unit is constituted by a plurality of leaf disk filters, the resin supply side and The pressure balance may be lost on the discharge side, and the filter may be damaged.

  In the method of the present invention, the reduced viscosity (ηsp / c) of the polycarbonate resin obtained by polycondensation by the transesterification reaction before being filtered through the filter is filtered using the filter A and the die is obtained. When the reduced viscosity (ηsp / c) of the polycarbonate resin pellets obtained by discharging in the form of strands and cooling and using a cutter after cooling is B, it is preferable to satisfy the following formula (2).

0.8 <B / A <1.1 (2)
More preferably, B / A> 0.85, still more preferably B / A> 0.9, and particularly preferably B / A> 0.95. When B / A is 0.8 or less, there is a tendency that a coloring component that is considered to be generated by a side reaction or a component that becomes a coloring precursor is generated, which is not preferable. On the other hand, when the reduced viscosity increases in the polymer filter, the generation of foreign matters such as gels and burns rises, so it is preferable that B / A ≦ 1.0. A method for measuring the reduced viscosity will be described later.

When the extruder is installed between the polycondensation reaction tank and the filter, when the reduced viscosity (ηsp / c) of the polycarbonate resin supplied to the extruder is a, For B, it is preferable to satisfy the following formula (8).
0.8 <B / a <1.1 (8)
More preferably, B / a> 0.85, and particularly preferably B / a> 0.9. When B / a is 0.8 or less, there is a tendency that a colored component considered to be generated by a side reaction or a component that becomes a colored precursor is generated, which is not preferable. On the other hand, when the reduced viscosity increases, the generation of foreign matters such as gels and burns rises, so it is preferable that B / a ≦ 1.0.

  In order to bring the change in the reduced viscosity in the polymer filter or extruder into the above range, the temperature of the polycarbonate resin in the final reaction tank, the temperature of the polycarbonate resin entering the polymer filter, the temperature of the polycarbonate resin discharged from the polymer filter, Selection of throughput and opening of the polymer filter per unit time, temperature control and residence time from the polymer filter to the die, when using an extruder, temperature of the polycarbonate resin supplied to the extruder, discharge from the extruder It is important to select the temperature, devolatilization pressure, water injection amount, water injection amount, screw rotation speed and peripheral speed, and element configuration of the polycarbonate resin to be used.

  Furthermore, when using the extruder, it is preferable to dispose a gear pump between the extruder and the filter in order to stabilize the supply amount of the polycarbonate resin to the filter. There are no restrictions on the type of gear pump, but in particular, a part of polymer from the discharge side of the gear pump is guided to the gland through the valve, a certain pressure is applied to the shaft seal, and there is a circuit that returns it to the suction port. A self-circulation type in which no gland packing is used for the part is preferable from the viewpoint of reducing foreign matter.

  In the present invention, in the case of stranding or pelletization in which the polycarbonate resin is in direct contact with the outside air, it is preferably class 7 as defined in JIS B 9920 (2002), more preferably, in order to prevent contamination by foreign matter from the outside air. It is desirable to carry out in a clean room with higher cleanliness than class 6.

  The polycarbonate resin filtered by the filter is cooled and solidified and pelletized by a rotary cutter or the like, and it is preferable to use a cooling method such as air cooling or water cooling when pelletizing. As the air used for air cooling, it is desirable to use air from which foreign substances in the air have been removed in advance with a hepa filter or the like to prevent reattachment of foreign substances in the air. When using water cooling, it is desirable to use water from which metal in water has been removed with an ion exchange resin or the like, and further, foreign matter in water has been removed with the filter. The opening of the filter to be used is preferably 10 to 0.45 μm as a filtration accuracy of 99.9% removal.

Further, in the present invention, a heat stabilizer, a neutralizing agent, an ultraviolet absorber, a release agent, a colorant, an antistatic agent, a lubricant, a lubricant, a plasticizer, a phase, which are generally known in the extruder. A solubilizer, a flame retardant, etc. can be added and kneaded.
Among these, addition of a phosphite ester or a hindered phenol heat stabilizer is preferable because it can suppress a decrease in molecular weight and a deterioration in color tone during extrusion or filtration of the polycarbonate resin of the present invention.

Specific examples of the phosphite ester heat stabilizer include triphenyl phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, tridecyl phosphite, Trioctyl phosphite, trioctadecyl phosphite, didecyl monophenyl phosphite, dioctyl monophenyl phosphite, diisopropyl monophenyl phosphite, monobutyl diphenyl phosphite, monodecyl diphenyl phosphite, monooctyl diphenyl phosphite, bis (2 , 6-Di-tert-butyl-4-methylphenyl) pentaerythrityl diphosphite, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite, bis (nonylphenyl) penta Lithylyl diphosphite, bis (2,4-di-tert-butylphenyl) pentaerythrityl diphosphite, distearyl pentaerythrityl diphosphite, tributyl phosphate, triethyl phosphate, trimethyl phosphate, triphenyl phosphate, diphenyl mono Orthoxenyl phosphate, dibutyl phosphate, dioctyl phosphate, diisopropyl phosphate, 4,4′-biphenylenediphosphinic acid tetrakis (2,4-di-tert-butylphenyl), benzenphosphonate dimethyl, benzenephosphonate diethyl, benzenephosphonate dipropyl Etc. Among them, trisnonylphenyl phosphite, trimethyl phosphate, tris (2,4-di-tert-butylphenyl) phosphite, bis (2,4-di-tert-butylphenyl) pentaerythrityl diphosphite, bis ( 2,6-di-tert-butyl-4-methylphenyl) pentaerythrityl diphosphite and dimethyl benzenephosphonate are preferably used. Among them, tris (2,4-di-tert-butylphenyl) phosphite is used. preferable.

Specific examples of the hindered phenol heat stabilizer include pentaerythrityl tetrakis (3-mercaptopropionate), pentaerythrityl tetrakis (3-lauryl thiopropionate), glycerol-3-stearyl thiopropioate. , Triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl -4-hydroxyphenyl) propionate], pentaerythrityltetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl- 4-hydroxyphenyl) propionate, 1,3,5-trimethyl 2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, N, N-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinna Mido), 3,5-di-tert-butyl-4-hydroxy-benzylphosphonate-diethyl ester, tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, 4,4′-biphenylenediphosphine Acid tetrakis (2,4-di-tert-butylphenyl), 3,9-bis {1,1-dimethyl-2- [β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy ]}}, 4,8,10-tetraoxaspiro (5,5) undecane or the like, preferably, Pentaerythrityltetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, particularly preferred Is pentaerythrityltetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate].

These heat stabilizers may be used alone or in combination of two or more. The blending amount of these heat stabilizers is preferably 0.0001 to 1 part by weight, more preferably 0.0005 to 0.5 part by weight, and 0.001 to 0.2, based on 100 parts by weight of the polycarbonate resin. Part by weight is more preferred.

  The yellowness index value measured by the reflected light of the polycarbonate resin pellet obtained by the method of the present invention is preferably 90 or less, more preferably 70 or less, particularly preferably 50 or less, and most preferably 40 or less. . In order to lower the yellowness index value, as described above, it is necessary to appropriately select the monomer preparation conditions, the polycondensation reaction conditions, the filtration conditions, and the extrusion conditions and screw elements when using an extruder.

  Further, the molecular weight of the polycarbonate resin obtained in the method of the present invention can be represented by a reduced viscosity (ηsp / c), and the reduced viscosity is usually 0.2 dL / g or more, preferably 0.25 dL / g or more, More preferably 0.3 dL / g or more, still more preferably 0.36 dL / g or more, usually 0.8 dL / g or less, preferably 0.6 dL / g or less, particularly preferably 0.5 dL / g or less. . If the reduced viscosity of the polycarbonate resin is too low, the mechanical strength of the molded product may be small, and if the stretching operation is performed after molding into a film, there is a possibility that stretching will be lost. On the other hand, if it is too large, not only the fluidity at the time of molding will decrease and the productivity and moldability will tend to be lowered, but also there is a possibility that the deterioration will be severe due to shear heat generation during filtration and extrusion. The reduced viscosity is precisely measured by using a Ubbelohde viscosity tube at a temperature of 20.0 ° C. ± 0.1 ° C. by accurately measuring polycarbonate resin pellets, using methylene chloride as a solvent, and preparing precisely at 0.6 g / dL. To do.

The melt viscosity at a shear rate of 91.2 sec ⁻¹ of the polycarbonate resin obtained by the method of the present invention measured at 260 ° C. is usually 500 Pa · s or more, preferably 1000 Pa · s or more, particularly preferably 1500 Pa · s or more. The upper limit is usually 5000 Pa · s or less, preferably 4000 Pa · s or less, particularly preferably 3000 Pa · s or less. If the melt viscosity is too low, the mechanical strength of the molded product tends to be inferior. If it is too high, as described above, the shear heat generated by the filter or the extruder increases, and the deterioration during filtration or extrusion may become severe. There is. In addition, since the melt viscosity varies depending on the molecular structure in addition to the molecular weight, it is important to select these according to the required performance and control them within the above range.

Although there is no restriction | limiting in the glass transition temperature of the polycarbonate resin obtained by the method of this invention, Usually, 50 degreeC or more, Preferably it is 110 degreeC or more, More preferably, it is 120 degreeC or more, and 130 degreeC or more is especially preferable. If the glass transition temperature is too low, the heat resistance is inferior, and therefore the reliability of the optical member may be inferior. On the other hand, if the glass transition temperature is high, the polycarbonate resin may deteriorate due to shear heat generation during extrusion, or the melt viscosity when filtering with a filter becomes too high, which may cause deterioration of the polycarbonate resin. Usually, it is less than 180 ° C., preferably 160 ° C. or less, more preferably 150 ° C. or less, particularly preferably 145 ° C. or less. The glass transition temperature can be measured with a differential scanning calorimeter (DSC), and the temperature at which the change in heat capacity appears at the lowest temperature (Tig) when measured at a heating rate of 20 ° C./min using about 10 mg of a sample. ) Is defined as the glass transition temperature in the present invention.

  In the transesterification performed in the present invention, when the polycarbonate resin of the present invention is produced using a substituted diphenyl carbonate such as diphenyl carbonate or ditolyl carbonate as the carbonic acid diester represented by the general formula (11), It is inevitable that aromatic monohydroxy compounds such as substituted phenols are by-produced and remain in the polycarbonate resin. Since these may cause generation of gas during filtration and odor during molding, using an extruder with a vacuum vent, preferably 2000 ppm by weight or less, more preferably 1000 ppm by weight or less, particularly preferably Is preferably 500 ppm by weight or less, and more preferably 20 ppm by weight or less. However, it is difficult to remove these compounds completely industrially, and the lower limit of the content of the aromatic monohydroxy compound is usually 1 ppm by weight. The concentration of the aromatic monohydroxy compound can be quantified by liquid chromatography, NMR, mass spectrum or the like.

  These aromatic monohydroxy compounds may naturally have a substituent depending on the raw material used, and may have, for example, an alkyl group having 5 or less carbon atoms. When diphenyl carbonate is used as the carbonic acid diester, the aromatic monohydroxy compound is phenol.

When the concentration of the remaining carbonic acid diester of the polycarbonate resin of the present invention is high, it causes gas generation in the filter unit or the like, and not only causes local deterioration of the polycarbonate resin by gas lock, but also induces disturbance of the strands. When it is processed into a film and stretched, it sublimates in the stretching device and accumulates in the device, causing it to fall on the stretched film and causing defects in the optical film. The concentration of the residual carbonic acid diester in the polycarbonate resin is preferably 200 ppm by weight or less, more preferably 100 ppm by weight or less, particularly preferably 60 ppm by weight or less, and particularly preferably 30 ppm by weight or less. However, it is difficult to remove the remaining carbonic acid diester completely industrially, and the lower limit of the content is usually 1 ppm. The concentration of the remaining carbonic acid diester can be quantified by liquid chromatography, NMR, mass spectrum or the like.
The concentration of the residual carbonic acid diester can be controlled by controlling the molar ratio of the raw material carbonic acid diester and the dihydroxy compound, as well as by the pressure of the final polymerization tank, the devolatilization conditions of the extruder, and the like.

<Example of manufacturing equipment>
An example of an apparatus for obtaining a polycarbonate resin from the raw material monomers described above is shown in the process diagram of FIG. 9,9-bis (4-hydroxy-3-methylphenyl) fluorene (BCF) and spiroglycol (SPG) are used as the raw dihydroxy compound, diphenyl carbonate (DPC) is used as the carbonic acid diester, and magnesium acetate is used as the polycondensation catalyst. It shall be.

  First, in the raw material preparation step, a DPC melt prepared at a predetermined temperature in a nitrogen gas atmosphere is continuously supplied from the raw material supply port 1a to the raw material mixing tank 2a. Also, the SPG melt or powder and the BCF powder weighed in a nitrogen gas atmosphere are continuously supplied to the raw material mixing tank 2a from the raw material supply ports 1b and 1c, respectively. And these are mixed by the stirring blade 3a in the raw material mixing tank 2a, and a uniform raw material mixing melt is obtained.

Next, the obtained raw material mixed melt is continuously supplied to the first vertical stirring reaction tank 6a via the raw material supply pump 4a and the raw material filtration filter 5a. Further, the raw material catalyst is continuously supplied as an aqueous solution from the catalyst supply port 1d in the middle of the raw material mixed melt transfer pipe.
In the polycondensation step of the production apparatus of FIG. 1, a first vertical stirring reaction tank 6a, a second vertical stirring reaction tank 6b, a third vertical stirring reaction tank 6c, and a fourth horizontal stirring reaction tank 6d are provided in series. It is done. In each reaction tank, the liquid level is kept constant, the polycondensation reaction is continuously performed, and the polycondensation reaction liquid discharged from the bottom of the first vertical stirring reaction tank 6a is the second vertical stirring reaction tank 6b. Subsequently, the polycondensation reaction proceeds sequentially by sequentially supplying the third vertical stirring reaction tank 6c to the fourth horizontal stirring reaction tank 6d. The reaction conditions in each reaction tank are preferably set so that the high temperature, high vacuum, and low stirring speed are achieved as the polycondensation reaction proceeds.

The first vertical stirring reaction tank 6a, the second vertical stirring reaction tank 6b, and the third vertical stirring reaction tank 6c are provided with Max Blend blades 7a, 7b, 7c, respectively. The fourth horizontal stirring reaction tank 6d is provided with a biaxial glasses-type stirring blade 7d. Since the reaction liquid to be transferred becomes highly viscous after the third vertical stirring reaction tank 6c, a gear pump 4b is provided.
In the first vertical stirring reaction tank 6a and the second vertical stirring reaction tank 6b, the amount of supplied heat may be particularly large, so that the internal heat exchangers 8a and 8b are respectively provided so that the heat medium temperature does not become excessively high. Is provided.

  In addition, distilling tubes 11a, 11b, 11c, and 11d for discharging by-products and the like generated by the polycondensation reaction are attached to the four reactors. For the first vertical stirring reaction tank 6a and the second vertical stirring reaction tank 6b, reflux condensers 9a and 9b and reflux pipes 10a and 10b are provided in order to return a part of the distillate to the reaction system. The reflux ratio can be controlled by appropriately adjusting the pressure in the reaction tank and the temperature of the heat medium in the reflux condenser.

The distillation pipes 11a, 11b, 11c, and 11d are connected to condensers 12a, 12b, 12c, and 12d, respectively, and the reaction tanks are in a predetermined depressurized state by depressurization devices 13a, 13b, 13c, and 13d. To be kept.
Further, by-products such as phenol (monohydroxy compound) are continuously liquefied and recovered from the condensers 12a, 12b, 12c, and 12d attached to each reaction tank. In addition, cold traps (not shown) are provided downstream of the condensers 12c and 12d attached to the third vertical stirring reaction tank 6c and the fourth horizontal stirring reaction tank 6d, respectively, so that by-products are continuously present. Solidified and recovered.

  The reaction liquid raised to a predetermined molecular weight is withdrawn from the fourth horizontal stirring reaction tank 6d, and the pipe connecting the extruder 15a by the gear pump 4c is a jacket-type double pipe in which the heat medium flows to the outside. Preferably, the temperature of the heat medium can be appropriately determined in consideration of the viscosity of the polycarbonate resin, the pressure loss of the piping, and the thermal stability of the polycarbonate resin. However, if the temperature is too high, the polycarbonate resin may be deteriorated or gas may be generated. Therefore, it is usually 300 ° C. or lower, preferably 280 ° C. or lower, more preferably 270 ° C. or lower, particularly preferably 260 ° C. or lower, and most preferably 250 ° C. or lower. On the other hand, if the pressure is too low, the pressure loss in the pipe becomes large and the pipe diameter needs to be increased, but at the same time, the residence time in the pipe of the polycarbonate resin may become long and may cause thermal deterioration. Above, preferably 180 ° C. or higher, more preferably 200 ° C. or higher, particularly preferably 210 ° C. or higher, and most preferably 220 ° C. or higher. The extruder 15a is equipped with a vacuum vent to remove residual low molecular components in the polycarbonate. Further, an antioxidant, a light stabilizer, a colorant, a release agent, and the like are added as necessary.

Resin is supplied to the filter 15b by the gear pump 4d from the extruder 15a, and foreign matter is filtered. The resin that has passed through the filter 15b is extracted in the form of a strand from the die 15c, and after cooling and solidifying the resin with water in the strand cooling tank 16a, the resin is pelletized by the strand cutter 16b. The polycarbonate resin pellets thus obtained are pneumatically transported by the air blower 16c and sent to the product hopper 16d. A predetermined amount of product is packed in the product bag 16f by the measuring instrument 16e.

There are no restrictions on the types of gear pumps 4c and 4d, but in particular, there is a circuit that introduces some polymer from the discharge side of the gear pump to the gland through the valve, applies a certain pressure to the shaft seal, and returns it to the suction port. A self-circulating seal type gear pump that does not use a gland packing at the seal portion is preferable from the viewpoint of reducing foreign matter.
The polycarbonate resin obtained by the method of the present invention is usually processed into a film by extrusion using the pellets produced as described above, and then stretched to obtain a retardation film, but after filtering under the above conditions The film can be directly formed into a film without being pelletized, or the film can be stretched.

According to the method of the present invention, a polycarbonate resin with less coloring and less foreign matter is obtained. Therefore, a foreign matter having a maximum length of 25 μm or more contained in a film having a thickness of 35 μm ± 5 μm obtained by extrusion molding from the resin is preferably used. It can be 500 pieces / m ² or less, more preferably 200 pieces / m ² or less, particularly preferably 100 pieces / m ² or less, and most preferably 50 pieces / m ² or less. Thus, the characteristic that there are few foreign substances is especially suitable when using polycarbonate resin for an optical use.

  Polycarbonate resin pellets obtained by the method of the present invention include, for example, aromatic polycarbonate, aromatic polyester, aliphatic polyester, polyamide, polystyrene, polyolefin, acrylic resin, amorphous polyolefin, ABS, AS and other synthetic resins, polylactic acid, poly It can also be used as a polymer alloy by kneading with one or more of biodegradable resins such as butylene succinate and rubber.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by a following example, unless the summary is exceeded. In the following, each evaluation was performed by the following method.
(1) Measurement of pH of spiroglycol 0.3 g of spiroglycol was weighed and put into 300 mL of pure water (electric conductivity at 25 ° C. of 0.1 μs / cm or less). The dispersion was stirred with a stirrer for 10 minutes, and then the pH was measured with a pH meter (HM-20P manufactured by Toa DKK Co., Ltd.).

(2) Measurement of oxygen concentration in the polycondensation reactor
An oxygen meter (manufactured by AMI: 1000RS) was used for measurement.
(3) Reduced viscosity of polycarbonate resin Polycarbonate resin was dissolved using methylene chloride as a solvent to prepare a polycarbonate solution having a concentration of 0.6 g / dL. Using an Ubbelohde type viscosity tube (manufactured by Moriyu Rika Kogyo Co., Ltd.), measurement is performed at a temperature of 20.0 ° C. ± 0.1 ° C., and the relative viscosity η _rel is calculated from the following equation from the solvent passage time t ₀ and the solution passage time t. Seeking
η _rel = t / t ₀
From the relative viscosity, the specific viscosity η _sp was determined from the following equation.

η _sp = (η−η ₀ ) / η ₀ = η _rel −1
The reduced viscosity η _sp / c was determined by dividing the specific viscosity by the concentration c (g / dL). The higher this value, the higher the molecular weight.
(4) Glass transition temperature of polycarbonate resin The glass transition temperature of the polycarbonate resin was measured using a differential scanning calorimeter (DSC 6220 manufactured by SII Nanotechnology). About 10 mg of a polycarbonate resin sample was put in an aluminum pan manufactured by the same company and sealed, and the temperature was raised from room temperature to 250 ° C. at a temperature rising rate of 20 ° C./min under a nitrogen stream of 50 mL / min. After maintaining the temperature for 3 minutes, it was cooled to 30 ° C. at a rate of 20 ° C./min. The temperature was maintained at 30 ° C. for 3 minutes, and the temperature was increased again to 200 ° C. at a rate of 20 ° C./min. From the DSC data obtained at the second temperature increase, the extrapolated glass transition start temperature was adopted.

  (5) Measurement of the structural unit ratio derived from each dihydroxy compound in the polycarbonate resin The structural unit ratio derived from each dihydroxy compound in the polycarbonate resin was obtained by weighing 30 mg of the polycarbonate resin and dissolving it in about 0.7 mL of deuterated chloroform. The solution was put into an NMR tube having an inner diameter of 5 mm, and a 1H NMR spectrum was measured at room temperature using JNM-AL400 (resonance frequency 400 MHz) manufactured by JEOL. The structural unit ratio derived from each dihydroxy compound was determined from the signal intensity ratio based on the structural unit derived from each dihydroxy compound.

(6) Measurement of phenol content and DPC content in polycarbonate resin Dissolve 1.00 g of polycarbonate resin sample in 5 ml of methylene chloride to make a solution, then add acetone to make the total amount 25 ml and reprecipitate. Went. The solution was filtered through a 0.2 μm disk filter and quantified by liquid chromatography.

(7) Method for evaluating initial hue of polycarbonate resin The hue of the polycarbonate resin was evaluated by measuring the yellowness index (YI) value in the reflected light of the pellet in accordance with ASTM D1925. As the apparatus, a spectrocolorimeter CM-5 manufactured by Konica Minolta Co., Ltd. was used, and the measurement conditions were a measurement diameter of 30 mm and SCE. A petri dish calibration glass CM-A212 was fitted into the measurement part, and a zero calibration box CM-A124 was placed thereon to perform zero calibration, followed by white calibration using a built-in white calibration plate. Measurement was performed using a white calibration plate CM-A210. L * was 99.40 ± 0.05, a * was 0.03 ± 0.01, b * was −0.43 ± 0.01, and YI was −. It was confirmed to be 0.58 ± 0.01. The pellets were measured by putting the pellets to a depth of 30 mm or more in a cylindrical glass container having an inner diameter of 30 mm and a height of 50 mm. The operation of taking out the pellet from the glass container and then performing the measurement again was repeated twice, and the average value of the measurement values of three times in total was used. The smaller the YI value, the better the quality without yellowness.

(8) Melt viscosity A sample dried at 120 ° C. for 6 hours was heated to 260 ° C. using a capillary rheometer (manufactured by Toyo Seiki Co., Ltd.) equipped with a die having a capillary with a diameter of 1 mmφ × length of 10 mmL. shear rate γ = 9.12~1824 ^{(sec -1)} was measured between reads the melt viscosity at 91.2Sec ^-1, and melt viscosity (Pa · s).

(9) Birefringence wavelength dispersibility Polycarbonate resin vacuum-dried at 120 ° C. for 5 hours is converted into a single screw extruder (made by Isuzu Chemical Industries, screw diameter 25 mm, cylinder set temperature: 250 ° C.), T-die (width 200 mm). , A film having a thickness of 100 μm ± 5 μm was prepared using a film forming apparatus equipped with a chill roll (set temperature: 130 to 140 ° C.) and a winder. A sample having a width of 6 cm and a length of 6 cm was cut out from this film. This sample was batch-biaxially stretched (manufactured by Toyo Seiki Co., Ltd.), the stretching temperature was the glass transition temperature of the polycarbonate resin + 15 ° C., the stretching rate was 600 mm / min (strain rate 1000% / min), and the stretching ratio was 2. A free end uniaxial stretching was performed 0 times to obtain a transparent film having a uniform thickness.

A sample obtained by cutting the transparent film into a width of 4 cm and a length of 4 cm is used as a phase difference measuring device (
A phase difference (R450) at a measurement wavelength of 450 nm and a phase difference (R550) at 550 nm were measured by KOBRA-WPR manufactured by Oji Scientific Instruments. And the ratio (R450 / R550) of the measured phase difference (R450) and phase difference (R550) was calculated. If the phase difference ratio is greater than 1, the chromatic dispersion is positive, and if it is less than 1, it is negative (reverse dispersion). It is shown that the smaller the ratio of the respective phase differences is less than 1, the stronger the negative wavelength dispersion.

(10) Evaluation method of the number of foreign substances: OPTICAL CONTROL SYSTEMS, manufactured by OPTICAL CONTROL SYSTEMS, single screw extruder (caliber 20 mm, single flight, L / D = 25), cast film die (150 mm width), chill roll, cylinder set temperature 250 ° C. A film having a thickness of 35 ± 5 μm was formed at a roll temperature of 133 ° C., and foreign matters of 25 μm or more were counted using a gel counter system (form FSA100).

(11) Operating time until the strand runs out of gas After purging the gas downstream from the filter unit, the time until the strand starts to run out of gas was measured. The shorter the time, the more gas is generated in the filter unit.
The abbreviations of the compounds used in the description of the following examples are as follows.
BCF: 9,9-bis (4-hydroxy-3-methylphenyl) fluorene (manufactured by Osaka Gas Chemical Co., Ltd.)
SPG: 3,9-bis (1,1-dimethyl-2-methoxyethyl) -2,4,8,10
-Tetraoxaspiro [5.5] undecane (spiroglycol) (Mitsubishi Gas Chemical Co., Ltd.)
・ DPC: Diphenyl carbonate (Mitsubishi Chemical Corporation)

[Example 1]
Raw material prepared so that the molar ratio of BCF / SPG / DPC is 0.300 / 0.700 / 1.020 in a raw material preparation tank sufficiently substituted with nitrogen (oxygen concentration 0.0005 vol% to 0.001 vol%) Is continuously supplied to a first polycondensation reaction tank equipped with a heat medium jacket using oil as a heat medium, a heat medium internal coil, a stirring blade, a distillation pipe connected to a vacuum pump and a condenser. At the same time, calcium acetate monohydrate in an aqueous solution was continuously supplied from a catalyst supply pipe connected to the raw material supply pipe so as to be 200 μmol (calcium metal atom equivalent) per 1 mol of all dihydroxy compounds. The pH of SPG was 5.6. After mixing the raw material and catalyst aqueous solution by piping, install two pleated cylindrical type raw material filtration filters in the flow path until entering the first reaction tank, the upstream raw material filtration filter opening is 10 μm, downstream The mesh opening was 1 μm. In the first polycondensation reaction tank, a reflux condenser using oil (inlet temperature 130 ° C.) as a refrigerant, and phenol and the like which are not condensed in the reflux condenser are condensed in the reflux condenser and the vacuum pump. A condenser using warm water (inlet temperature 45 ° C.) as a refrigerant was disposed between them. While keeping the rotation speed of the stirring blade of the first polycondensation reaction tank constant, the internal temperature is controlled to be constant at 210 ° C., the pressure is 26.3 kPa, and the residence time is 1.5 hours, and the reaction liquid is continuously supplied from the bottom of the reaction tank. It was extracted and supplied to the second polycondensation reaction tank. As with the first polycondensation reaction tank, the second polycondensation reaction tank includes a heat medium jacket, a heat medium internal coil, a stirring blade, a distillation pipe connected to a vacuum pump, and a distillation pipe including a reflux condenser and a condenser. The inner temperature was 220 ° C., the pressure was 20.0 kPa, and the residence time was controlled to be constant at 1 hour. The reaction solution was continuously withdrawn from the bottom of the reaction vessel and supplied to the third polycondensation reaction vessel. . The third polycondensation reaction tank is controlled so as to be constant at an internal temperature of 240 ° C., a pressure of 3.0 kPa, and a residence time of 1 hour, and then the polycondensation reaction proceeds while distilling off the by-produced phenol. Horizontal stirring reaction with two horizontal rotating shafts and discontinuous stirring blades mounted almost at right angles to the horizontal axis, continuously extracted from the reaction vessel bottom using a self-circulating sealed gear pump It supplied to the tank (4th polycondensation reaction tank). The fourth polycondensation reaction tank is controlled so that the internal temperature near the inlet is 245 ° C., the internal temperature near the outlet is 260 ° C., the pressure is 0.2 kPa, and the residence time is 2 hours, and further the polycondensation reaction proceeds. It was. The obtained polycarbonate resin has an additive supply port and three vent ports, L / D = 42, the length of the kneading disk occupying the length of the element constituting the entire screw of the extruder (kneading element) A self-circulating seal type gear pump was continuously supplied to a twin screw extruder having a ratio of 6%. The pipe connecting the gear pump and the extruder is a jacket-type double pipe through which the heat medium flows to the outside, and the temperature of the heat medium was set to 270 ° C. The temperature of the resin supplied to the extruder was 262 ° C. as measured with a resin thermometer installed at the inlet of the extruder. In the extruder, 0.1% of water was supplied to the polycarbonate resin to be treated, and the vent port was connected to a vacuum pump to remove volatile components contained in the polycarbonate resin. As for the heater temperature of the barrel of the extruder, the upstream 4 blocks were 250 ° C., the downstream 6 blocks were 230 ° C., and the screw rotation speed was 274 rpm. At this time, the polycarbonate resin supplied to the extruder was temporarily extracted and subjected to various analyses. The results are shown in Table 1.
In Table 1, the kneading element ratio is a value calculated from the following formula.

Kneading element ratio (%) = (total length of kneading disc / total length of screw) × 100
The polycarbonate resin processed by the extruder was supplied to a filter unit having a resin inlet at the bottom and an outlet at the top through a gear pump installed at the outlet. Table 1 shows the temperature of the resin sampled before the filter unit and various measured values. Inside the filter unit, a leaf disk filter (manufactured by Nippon Pole Co., Ltd.) (material is stainless steel (SUS304, SUS316)), which is a metal nonwoven fabric sintered with filter media and having an aperture of 7 μm, is a polycarbonate resin. Foreign matter inside was removed. Before use, the filter was roasted at 310 ° C. for 40 hours in a water vapor atmosphere and then at 420 ° C. for 52 hours in an air atmosphere, cooled to room temperature, and then immersed in a 30% by weight nitric acid aqueous solution for 30 minutes. Then, an oxide film was formed, washed and dried. The filter unit was equipped with a heater composed of a plurality of blocks, and each temperature was set to 250 ° C. On the outlet side of the filter unit, a die was installed through a polymer pipe equipped with a heater composed of a plurality of blocks. The set temperature of the heater of the polymer pipe was set to 250 ° C., and the heater of the dice was set to 245 ° C. A sensor for measuring the resin temperature was installed in the outlet channel of the filter unit. The temperature of the polycarbonate resin discharged from the die was measured using a thermometer. The resin temperature at the die outlet was directly measured by inserting a thermometer into the die hole. The polycarbonate resin was extracted in the form of a strand in a room maintained at class 6 cleanliness from the die, solidified in a water tank, and pelletized with a rotary cutter. The analytical values are shown in Table 1. The reduced viscosity (ηsp / c) of the polycarbonate resin is a value of pellets obtained by filtering using this filter, discharging from a die in the form of a strand, cooling, and then using a cutter.

[Example 2]
The same procedure as in Example 1 was performed except that a portion of the polycarbonate resin was extracted from the middle of the piping supplied to the extruder from the fourth polycondensation reaction tank, and the amount of polycarbonate resin supplied to the extruder was reduced to half.
[Example 3]
In Example 1, it carried out like Example 1 except having changed the ratio of the kneading element of the screw of an extruder.

[Comparative Example 1]
In Example 1, the same procedure as in Example 1 was performed, except that the filter for filtering the polycarbonate resin was neither roasted nor treated with nitric acid. The resulting pellets and film were remarkably colored and foreign matter increased.

1a Raw material (carbonic acid diester) supply port 1b, 1c Raw material (dihydroxy compound) supply port 1d Catalyst supply port 2a Raw material mixing tank 3a Anchor type stirring blade 4a Raw material mixed liquid transfer pump 4b, 4c, 4d Gear pump 5a Raw material filtration filter 6a First Vertical stirring reaction tank 6b Second vertical stirring reaction tank 6c Third vertical stirring reaction tank 6d Fourth horizontal stirring reaction tank 7a, 7b, 7c Max blend blade 7d Biaxial glasses stirring blade 8a, 8b Internal heat exchanger 9a, 9b Reflux coolers 10a, 10b Reflux pipes 11a, 11b, 11c, 11d Distillate pipes 12a, 12b, 12c, 12d Condensers 13a, 13b, 13c, 13d Depressurizer 14a Distillate recovery tank 15a Extruder 15b Polymer Filter 15c Die 16a Strand cooling tank 16b Strand cutter 16c Air feed blower 16 Product hopper 16e meter 16f product bag (paper bag, such as a flexible container)

Claims (27)

A method for producing a polycarbonate resin obtained by polycondensing a raw material composition containing at least a dihydroxy compound represented by the following formula (1) and the following formula (2) with a carbonic acid diester,
The dihydroxy compound represented by the following formula (1) is 50 mol% or more with respect to all dihydroxy compounds constituting the raw material composition,
A method for producing a polycarbonate resin, wherein the polycarbonate resin is filtered using a filter having a filter medium made of a metal nonwoven fabric heat-treated at a temperature of 330 ° C. or higher and 600 ° C. or lower.
(In the formula (1), R _{1 to} R ₄ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted carbon group having 5 to 20 carbon atoms. A cycloalkyl group or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms is represented.)
(In the formula (2), R _{5 to} R ₈ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted 6 to 20 carbon atoms. A cycloalkyl group or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms is represented.)   The method for producing a polycarbonate resin according to claim 1, wherein the dihydroxy compound represented by the formula (2) is 5 mol% or more and 50 mol% or less with respect to all dihydroxy compounds constituting the raw material composition.   The method for producing a polycarbonate resin according to claim 1 or 2, wherein the heat treatment of the filter is performed in the presence of at least one of water vapor and oxygen.   The method for producing a polycarbonate resin according to any one of claims 1 to 3, wherein the filter is acid-treated. The filter is stored in a container, and a value obtained by dividing the internal volume (m ³ ) of the storage container by the flow rate (m ³ / min) of the polycarbonate resin to be filtered is 2 to 10 minutes. The method for producing a polycarbonate resin according to any one of 1 to 4.   The method for producing a polycarbonate resin according to claim 5, wherein the polycarbonate resin is supplied from a lower portion of the containment vessel of the filter, and the filtered polycarbonate resin is discharged from an upper portion of the containment vessel.   The method for producing a polycarbonate resin according to any one of claims 1 to 6, wherein a linear velocity of the molten resin on the filter surface is 0.01 to 0.5 m / h.   The method for producing a polycarbonate resin according to any one of claims 1 to 7, wherein an opening of the filter is 50 µm or less.   The method for producing a polycarbonate resin according to any one of claims 1 to 8, wherein the temperature of the polycarbonate resin after filtration using the filter is 220 ° C or higher and 280 ° C or lower.   The production of the polycarbonate resin according to any one of claims 1 to 9, wherein at least one of the dihydroxy compounds represented by the formulas (1) and (2) is filtered through a filter before the polycondensation reaction. Method.   The manufacturing method of the polycarbonate resin of any one of Claims 1 thru | or 10 whose glass transition temperature of the said polycarbonate resin is 50 to 180 degreeC.   The method for producing a polycarbonate resin according to any one of claims 1 to 11, wherein the reduced viscosity (ηsp / c) of the polycarbonate resin is 0.3 dL / g or more and 0.6 dL / g or less. The polycarbonate resin according to any one of claims 1 to 12, wherein the polycarbonate resin has a melt viscosity at a shear rate of 91.2 sec ^-1 measured at 260 ° C of 500 Pa · s to 3000 Pa · s. Production method.   The method for producing a polycarbonate resin according to any one of claims 1 to 13, wherein the polycarbonate resin obtained by the polycondensation is supplied to the filter in a molten state without being solidified and filtered.   The method for producing a polycarbonate resin according to any one of claims 1 to 14, wherein the polycarbonate resin is devolatilized by an extruder having a vent port, and then supplied to the filter and filtered.   The screw of the extruder is composed of a plurality of elements, at least one of the elements is a kneading disk, and the total length of the kneading disk is 20% or less of the total length of the screw. The method for producing a polycarbonate resin according to claim 15. The following formula (4) is satisfied, where W (kg / h) is the weight of the resin extruded per hour by the extruder and S (m ² ) is the cross-sectional area of the barrel of the extruder. Or the manufacturing method of polycarbonate resin of 16.
12000 ≤ W / S ≤ 60000 (4)   The manufacturing method of the polycarbonate resin of any one of Claims 15 thru | or 17 whose temperature of the polycarbonate resin supplied to the said extruder is 200 degreeC or more and 280 degrees C or less.   The method for producing a polycarbonate resin according to any one of claims 1 to 18, wherein a temperature of the polycarbonate resin supplied to the filter is 230 ° C or higher and 280 ° C or lower. The barrel constituting the extruder includes a plurality of heaters, and in at least one combination of the heaters, the set temperature of the heater is not higher than the heater set temperature adjacent to the polycarbonate resin supply side of the extruder, The method for producing a polycarbonate resin according to any one of claims 15 to 19.   The method for producing a polycarbonate resin according to any one of claims 15 to 20, wherein a gear pump is disposed between the extruder and the filter.   The method for producing a polycarbonate resin according to any one of claims 1 to 21, wherein the content of the aromatic monohydroxy compound contained in the polycarbonate resin is 1 ppm by weight or more and 1000 ppm by weight or less. The polycondensation is performed using a catalyst;
The catalyst is a compound containing at least one metal selected from the group consisting of metals of Group 1 or Group 2 of the long-period periodic table, and is used in an amount of 10 µmol or more as a metal amount with respect to 1 mol of all dihydroxy compounds. The method for producing a polycarbonate resin according to any one of 1 to 22.   The method for producing a polycarbonate resin according to claim 23, wherein the catalyst is a compound containing at least one metal selected from the group consisting of a metal of Group 2 of the long-period periodic table and lithium.   The method for producing a polycarbonate resin according to any one of claims 1 to 24, wherein the pH of the dihydroxy compound represented by the formula (1) is 5 or more.   A film obtained by molding a polycarbonate resin obtained by the method for producing a polycarbonate resin according to any one of claims 1 to 25 by melt extrusion. A retardation film obtained by stretching the film according to claim 26 and satisfying a relationship of the following formula (6).
0.70 <R (450) / R (550) <1.00 (6)
(However, R (450) and R (550) represent retardation values in the film plane at wavelengths of 450 nm and 550 nm, respectively).