JP7552389B2 - Polycarbonate resin manufacturing method - Google Patents

Description

The present invention relates to a production method for strict control of the primary polymer structure of a polycarbonate resin and stabilizing the quality of the resin, such as its optical properties and mechanical properties.

With the recent development of the flat panel display field, optical films used as components are required to have further improved performance and quality, as well as improved productivity and reduced costs. Copolymerized polycarbonates using spiroglycol (SPG) as a monomer have been developed as materials for optical films, and it has been disclosed that SPG is excellent in heat resistance and optical properties, particularly in that it has a low photoelastic coefficient (for example, Patent Documents 1 to 3). Furthermore, methods for stabilizing polymerization reactivity and quality when producing polycarbonate resins using SPG have also been studied. In Patent Document 4, the amount of acidic components contained in SPG is reduced to reduce gels in the resulting polycarbonate resin. Patent Document 5
In this method, the decomposition of SPG is suppressed by reducing the heat history in the raw material preparation step in the continuous polymerization process, thereby stabilizing the quality of the obtained polycarbonate resin.

JP 2006-232897 A International Publication No. 2008/156186 JP 2015-212816 A JP 2011-26499 A JP 2012-214774 A

According to the study by the present inventors, even the methods of Patent Document 4 and Patent Document 5 cause fluctuations in the polymer primary structure of the obtained polycarbonate resin, particularly in the molecular weight distribution, and have found a problem that the physical properties of the optical film (retardation film) become unstable due to the fluctuations. If there is such variation in the quality of the resin, the yield rate, especially in the stretching process, will decrease, leading to deterioration in productivity and cost. It is required to completely stabilize the polymer primary structure of the obtained polycarbonate resin by suppressing even the slightest decomposition of SPG.
An object of the present invention is to provide a method for producing a polycarbonate resin which is excellent in optical properties, mechanical properties, etc. and has good quality uniformity.

As a result of intensive research to solve the above problems, the present inventors have discovered that in the raw material preparation process,
It has been found that the variation in the primary structure of the polymer can be effectively suppressed by contacting a dihydroxy compound having an acetal group in a part of its structure, such as G, with a basic compound.

[1] A method for producing a polycarbonate resin by continuously supplying a dihydroxy compound (A) having an acetal group in a part of its structure, a carbonic acid diester, and a polymerization catalyst to a reactor to carry out a melt polycondensation reaction, comprising the steps of:
The method includes a step of dissolving the dihydroxy compound (A) in a solvent containing a monohydroxy compound represented by the following formula (1) as a main component in a raw material dissolving tank,
The method for producing a polycarbonate resin, wherein the solvent contains a basic compound.

(R ¹ and R ² in formula (1) each independently represent a hydrogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, an optionally substituted acyl group having 1 to 10 carbon atoms, an optionally substituted alkoxy group having 1 to 10 carbon atoms, or an optionally substituted alkyl ester group having 1 to 10 carbon atoms.)
[2] The method for producing a polycarbonate resin according to the above [1], wherein the internal temperature of the raw material dissolving tank is 80° C. or higher and 150° C. or lower.
[3] The dihydroxy compound (A) is continuously supplied to the raw material dissolver, and a solution containing the dissolved dihydroxy compound (A) is continuously discharged from the raw material dissolver.
Or a method for producing the polycarbonate resin according to [2].
[4] The dihydroxy compound (A) is a compound represented by the following formula (2),
A method for producing a polycarbonate resin according to any one of items 1] to 3).

[5] The method for producing a polycarbonate resin according to any one of the above [1] to [4], wherein the content of a component detected at 5.7 to 5.8 ppm in a ¹ H-NMR spectrum of the polycarbonate resin measured using a deuterated chloroform solvent is 0.05 mol % or less relative to the total amount of structural units derived from the compound represented by formula (2).
[6] The method for producing a polycarbonate resin according to any one of [1] to [5] above, wherein the basic compound is at least one metal compound selected from the group consisting of metals in Group 2 of the long form periodic table and lithium.
[7] The above-mentioned [1] to [13], wherein the content of the basic compound in the solvent is 0.1 μmol or more and 50 μmol or less relative to 1 mol of the total dihydroxy compounds used in the melt polycondensation reaction.
[6] A method for producing a polycarbonate resin according to any one of [6].
[8] The carbonic acid diester is a compound represented by the following formula (3),
] The method for producing the polycarbonate resin according to any one of the above items.

(R ¹ and R ² in formula (3) each independently represent a hydrogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, an optionally substituted acyl group having 1 to 10 carbon atoms, an optionally substituted alkoxy group having 1 to 10 carbon atoms, or an optionally substituted alkyl ester group having 1 to 10 carbon atoms.)
[9] The method for producing a polycarbonate resin according to any one of the above [1] to [8], further comprising a step of recovering a monohydroxy compound produced as a by-product in a polycondensation reaction and purifying the recovered monohydroxy compound by distillation, and the distilled and purified monohydroxy compound is supplied to the raw material dissolving tank.
[10] The method for producing a polycarbonate resin according to any one of the above [1] to [9], wherein the polycarbonate resin contains a structural unit derived from a dihydroxy compound represented by the following formula (4):

[11] The method for producing a polycarbonate resin according to any one of [1] to [10] above, wherein the polycarbonate resin contains a structural unit derived from a compound represented by the following formula (5):

In formula (5), R ³ and R ⁴ each independently represent a direct bond or an alkylene group having 1 to 4 carbon atoms which may have a substituent. R ⁵ to R ¹⁰ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or a substituted alkyl group having 6 carbon atoms which may have a substituent.
an aryl group having 1 to 15 carbon atoms which may be substituted; an acyl group having 1 to 10 carbon atoms which may be substituted; an alkoxy group having 1 to 10 carbon atoms which may be substituted;
an aryloxy group having 1 to 10 carbon atoms which may have a substituent, an amino group which may have a substituent, a vinyl group having 2 to 10 carbon atoms which may have a substituent, an ethynyl group having 2 to 10 carbon atoms which may have a substituent, a sulfur atom which has a substituent, a silicon atom which has a substituent, a halogen atom, a nitro group, or a cyano group, provided that R ⁵
At least two adjacent groups among R 1 to R ¹⁰ may be bonded to each other to form a ring.
X is a hydroxy group, a carboxy group, an alkyl ester group having 1 to 10 carbon atoms which may have a substituent, or an aryl ester group having 6 to 15 carbon atoms which may have a substituent.
)

According to the present invention, it is possible to stably produce polycarbonate resins having excellent optical properties, mechanical properties, etc., and good quality uniformity. In addition, transparent films produced by forming polycarbonate resins produced by the present method can be suitably used for optical applications such as retardation films.

FIG. 2 is a process diagram showing a raw material preparation process in a polymerization facility A in the production method of the present invention. FIG. 2 is a process diagram showing a raw material preparation process in polymerization equipment B in the production method of the present invention. FIG. 2 is a process diagram showing the polymerization step and the distillation step in polymerization equipment A and B in the production method of the present invention. 1 is a ¹ H-NMR spectrum of the polycarbonate resin produced in Example 1. 1 is a ¹ H-NMR spectrum of the polycarbonate resin produced in Comparative Example 1.

The present invention will be described in detail below, but the present invention is not limited to the following description and can be modified in any manner without departing from the gist of the present invention.

In this specification, when "~" is used to express a numerical value or a physical property value,
It will be used including the values before and after it.

In this specification, the term "repeated structural unit" refers to a structural unit in which the same structure appears repeatedly in a resin, and each of the structural units is linked to form the resin. For example, in the case of a polycarbonate resin, the carbonyl group is also referred to as the repeating structural unit. In addition, the term "structural unit" refers to a partial structure that constitutes a resin, and a specific partial structure contained in the repeating structural unit. For example, it refers to a partial structure sandwiched between adjacent linking groups in a resin, or a partial structure sandwiched between a polymerizable reactive group present at the end of a polymer and a linking group adjacent to the polymerizable reactive group. More specifically, in the case of a polycarbonate resin, a carbonyl group is the linking group, and a partial structure sandwiched between adjacent carbonyl groups is referred to as a structural unit. In this specification, the weight ratio of each structural unit in a polycarbonate resin is calculated by assuming the total weight of all structural units and linking groups to be 100% by weight.

The method for producing a polycarbonate resin of the present invention is a method for producing a polycarbonate resin by continuously supplying a dihydroxy compound having an acetal group as a part of its structure (hereinafter, may be referred to as "dihydroxy compound (A)"), a carbonic acid diester, and a polymerization catalyst to a reactor to carry out a melt polycondensation reaction, and is characterized in that it includes a step of dissolving the dihydroxy compound (A) in a solvent containing, as a main component, a monohydroxy compound represented by the following formula (1) in a raw material dissolving tank, and the solvent contains a basic compound.

In formula (1), R ¹ and R ² each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group having 1 carbon atom.
an optionally substituted acyl group having 1 to 10 carbon atoms; an optionally substituted alkoxy group having 1 to 10 carbon atoms; and an optionally substituted alkyl ester group having 1 to 10 carbon atoms.

The dihydroxy compound (A) used in the method of the present invention contains an acetal group in a part of its structure. The acetal group is prone to decomposition reactions such as hydrolysis when even a trace amount of acidic substance is present, and the decomposition reaction may be accelerated by heat during liquefaction of the dihydroxy compound (A) and maintenance of the molten state associated with the continuous polymerization method described below. When decomposition occurs, a polyfunctional alcohol is produced. When a polymerization reaction is carried out in the presence of a polyfunctional alcohol, a branched structure is produced in the polymer molecule, and the molecular weight distribution increases. Since the branched structure changes the melt processing characteristics and mechanical properties of the resin, the quality of the obtained polycarbonate resin can be stabilized by suppressing the decomposition of the dihydroxy compound (A).

The method of the present invention includes a step of dissolving a dihydroxy compound (A) in a solvent containing a monohydroxy compound represented by the formula (1) as a main component in a raw material dissolving tank. The dihydroxy compound (A) has a relatively high melting point, so a high temperature is required to melt it alone. Therefore, by dissolving the dihydroxy compound (A) in a solvent containing a monohydroxy compound represented by the formula (1) as a main component, which has a lower melting point than the dihydroxy compound (A) and has the solubility of the dihydroxy compound (A), the dissolution temperature can be kept low and the above-mentioned decomposition reaction can be suppressed. In addition, since the monohydroxy compound represented by the formula (1) is also a by-product of the polymerization reaction, the monohydroxy compound produced in the polymerization step can be recovered,
By purifying it as necessary, it can be reused, which reduces costs and the environmental burden.

Furthermore, the solvent containing the monohydroxy compound represented by formula (1) used in the method of the present invention as a main component contains a basic compound. It is considered that the acidic impurities can be neutralized and decomposition can be suppressed by contacting the dihydroxy compound (A) with a basic compound before heat is substantially applied. Since the basic compound used here is directly carried over to the polymerization step, it is preferable to use a compound that does not adversely affect the polymerization reactivity or the quality of the obtained polycarbonate resin. Therefore, it is preferable to use the polymerization catalyst used in the method of the present invention as the basic compound that stabilizes the dihydroxy compound (A). The detailed method will be described below.

[Raw material for polycarbonate resin]
The polycarbonate resin of the present invention contains a structural unit derived from a dihydroxy compound (A) having an acetal group as part of its structure. The dihydroxy compound (A) is not particularly limited as long as it has an acetal group as part of its structure, but is preferably a dihydroxy compound having a cyclic acetal structure. Examples of dihydroxy compounds having a cyclic acetal structure include those represented by the following formula (2) incorporating a structure derived from pentaerythritol:
Spiroglycol (also known as 3,9-bis(1,1-dimethyl-2
-hydroxyethyl-2,4,8,10-tetraoxaspiro[5,5]undecane) and dioxane glycol (
(Also known as 2-(1,1-dimethyl-2-hydroxyethyl)-5-ethyl-5-hydroxymethyl-1,3-dioxane), dihydroxy compounds incorporating a structural unit derived from inositol as disclosed in JP-A-2016-117899, and the like can be used.

Polycarbonate resins using such dihydroxy compounds containing acetal groups are excellent in heat resistance and optical properties, particularly in terms of low photoelastic coefficient, and can be suitably used for optical film applications. Among the above-mentioned dihydroxy compounds, spiroglycol is particularly useful from the viewpoints of high performance and easy availability.

The polycarbonate resin of the present invention preferably contains 1% by weight or more and 90% by weight or less of the structural unit derived from the dihydroxy compound (A). The lower limit is more preferably 5% by weight or more, and particularly preferably 10% by weight or more. The upper limit is more preferably 80% by weight or less, and particularly preferably 70% by weight or less. By setting it in this range, it is possible to obtain a resin that is excellent in balance of various physical properties such as melt processability and mechanical properties while expressing the excellent optical properties of the dihydroxy compound (A).

The acetal group of the dihydroxy compound (A) has a structure that is vulnerable to acid, and when decomposition occurs, the aforementioned polyfunctional alcohol such as pentaerythritol is generated, which increases the molecular weight distribution of the resulting polycarbonate resin and may change the physical properties of the resin. Since a strong acid is generally used as a catalyst in the synthesis of the dihydroxy compound (A), the dihydroxy compound (A) may contain a trace amount of the acid catalyst remaining.
In the case of the above-mentioned, the content of the acid catalyst and other acidic substances is preferably 5 ppm by weight or less, more preferably 3 ppm by weight or less, and particularly preferably 1 ppm by weight or less.

The polycarbonate resin of the present invention may contain structural units other than the structural units derived from the dihydroxy compound (A) (hereinafter, these may be referred to as "other structural units"). Examples of compounds forming the other structural units include aliphatic dihydroxy compounds, alicyclic dihydroxy compounds, oxyalkylene glycols, aromatic-containing dihydroxy compounds,
Examples of the polycarbonate resin include diester compounds. A polycarbonate resin partially incorporating structural units derived from a diester compound is called a polyester carbonate resin. In this specification, the term "polycarbonate resin" includes polyester carbonate resins.

Examples of the aliphatic dihydroxy compound include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,3-pentanediol,
1,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1
,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 1,
6-Hexanediol, 1,7-Heptanediol, 1,8-Octanediol, 1,9
-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,1
Linear aliphatic dihydroxy compounds such as 2-dodecanediol, neopentyl glycol, 2
Examples of branched chain aliphatic dihydroxy compounds include 1,3-ethyl-1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol, hydrogenated dilinoleyl glycol, and hydrogenated dioleyl glycol.
From the viewpoints of availability and ease of handling, linear aliphatic dihydroxy compounds such as 1,4-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol are preferred.

Examples of the alicyclic dihydroxy compound include the following dihydroxy compounds: a dihydroxy compound represented by the following formula (4), 1,2-cyclohexanedimethanol,
Dihydroxy compounds which are primary alcohols of alicyclic hydrocarbons, exemplified by 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, pentacyclopentadecane dimethanol, 2,6-decalin dimethanol, 1,5-decalin dimethanol, 2,3-decalin dimethanol, 2,3-norbornane dimethanol, 2,5-norbornane dimethanol, 1,3-adamantanedimethanol, and dihydroxy compounds derived from terpene compounds such as limonene; dihydroxy compounds which are secondary or tertiary alcohols of alicyclic hydrocarbons, exemplified by 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,3-adamantanediol, hydrogenated bisphenol A, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol.

The dihydroxy compound represented by the above formula (4) includes isosorbide, isomannide, and isoidite, which are stereoisomers.
Of these, isosorbide, which is available in abundance as a resource and is easily available, and is obtained by dehydration condensation of sorbitol produced from various starches, is most preferred in terms of availability, ease of production, and moldability.
These dihydroxy compounds (4) may be used alone or in combination of two or more.

As the oxyalkylene glycol, for example, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. can be used.

Examples of aromatic dihydroxy compounds include the following dihydroxy compounds: 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4
-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-diethylphenyl)propane, 2,2-bis(4-hydroxy-(3-phenyl)phenyl)propane, 2,2-bis(4-hydroxy-(3,5-diphenyl)phenyl)propane, 2,2-bis(4-
hydroxy-3,5-dibromophenyl)propane, bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)pentane, 1,1-bis(
4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane, 1,1-bis(4-hydroxyphenyl)-2-ethylhexane, 1,1
-Bis(4-hydroxyphenyl)decane, bis(4-hydroxy-3-nitrophenyl)methane, 3,3-bis(4-hydroxyphenyl)pentane, 1,3-bis(2-(4
-hydroxyphenyl)-2-propyl)benzene, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(
4-hydroxyphenyl)sulfone, 2,4'-dihydroxydiphenyl sulfone, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxy-3-methylphenyl)
aromatic bisphenol compounds such as 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3,3'-dichlorodiphenyl ether, 2,2-bis(4-(2-hydroxyethoxy)phenyl)propane, 2,2-bis(4-(2-hydroxypropoxy)phenyl)propane,
Dihydroxy compounds having an ether group bonded to an aromatic group, such as 1,3-bis(2-hydroxyethoxy)benzene, 4,4'-bis(2-hydroxyethoxy)biphenyl, and bis(4-(2-hydroxyethoxy)phenyl)sulfone; 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9-bis(4-hydroxyphenyl)fluorene, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, and the like.
Bis(4-(2-hydroxypropoxy)phenyl)fluorene, 9,9-bis(4-(
2-hydroxyethoxy)-3-methylphenyl)fluorene, 9,9-bis(4-(2
-hydroxypropoxy)-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
Dihydroxy compounds having a fluorene ring, such as 9,9-bis(4-(2-hydroxyethoxy)-3,5-dimethylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butyl-6-methylphenyl)fluorene, and 9,9-bis(4-(3-hydroxy-2,2-dimethylpropoxy)phenyl)fluorene.

Examples of the diester compound include the following dicarboxylic acids: aromatic dicarboxylic acids such as terephthalic acid, phthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-benzophenonedicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid; 1,2-cyclohexanedicarboxylic acid;
Alicyclic dicarboxylic acids such as 1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; and aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, etc. These dicarboxylic acid components can be used as raw materials for polyester carbonate resins as dicarboxylic acids themselves, but depending on the production method, dicarboxylic acid esters such as methyl esters and phenyl esters, and dicarboxylic acid derivatives such as dicarboxylic acid halides can also be used as raw materials.

When other structural units are introduced into the polycarbonate resin of the present invention, they are preferably used for the purpose of adjusting heat resistance, melt processability, optical properties, mechanical properties, compatibility with other resins, etc. Among the above-mentioned other structural units, from the viewpoint of adjusting the optical properties, mechanical properties, etc., particularly properties required for optical film applications, it is preferable to use an aliphatic dihydroxy compound or an alicyclic dihydroxy compound. Among them, it is more preferable to use an alicyclic dihydroxy compound, and the dihydroxy compound represented by the above formula (4), 1,4-cyclohexanedimethanol, and tricyclodecane dimethanol are particularly useful.

When the polycarbonate resin of the present invention contains other structural units, the content of the other structural units in the polycarbonate resin of the present invention is preferably 1% by weight or more, more preferably 5% by weight or more, particularly preferably 10% by weight or more. Also, it is preferably 80% by weight or less.
It is more preferably 70% by weight or less, and particularly preferably 60% by weight or less.
It is possible to adjust the balance of other physical properties such as heat resistance, melt processability, etc., without significantly impairing the excellent properties of the dihydroxy compound (A). When the polycarbonate resin of the present invention contains two or more types of structural units as other structural units, the content ratio of the other structural units is the total value of those structural units.

By using aromatic dihydroxy compounds or diester compounds such as bisphenol compounds as copolymerization components, the heat resistance of polycarbonate resins can be improved in some cases, but on the other hand, when the polycarbonate resin contains a large amount of aromatic structures, the optical properties, particularly the photoelastic coefficient, tend to deteriorate. In addition, since there is a large difference in the polymerization reactivity between bisphenol compounds or diester compounds and dihydroxy compounds (A), the bisphenol compounds or diester compounds remain in the terminal groups, making it difficult to obtain a polycarbonate resin with a high molecular weight, and the mechanical properties tend to deteriorate. If the reaction temperature is raised to a high level in order to promote the reaction, the dihydroxy compound (A) is thermally decomposed, and the obtained polycarbonate resin tends to become colored or a branched structure is generated. For these reasons, the content of structural units derived from aromatic dihydroxy compounds or diester compounds (excluding structural units derived from the compound represented by the following formula (5)) is preferably 10% by weight or less, and more preferably 5% by weight or less.
% by weight or less is more preferable.

The polycarbonate resin of the present invention may contain, as another structural unit, a structural unit derived from a compound represented by the following formula (4).

In the resin used in the present invention, the structural unit represented by the formula (4) is 5% by mass or more,
The content is preferably 80% by mass or less. The upper limit is more preferably 70% by mass or less, and particularly preferably 50% by mass or less. The lower limit is more preferably 10% by mass or more, and particularly preferably 15% by mass or more.
When the content of the structural unit represented by the formula (4) is within the above range,
This results in a resin with better mechanical properties and heat resistance and a lower photoelasticity coefficient.

The polycarbonate resin of the present invention may contain, as another structural unit, a structural unit derived from a compound represented by the following formula (5).

In formula (5), ^R3 and ^R4 each independently represent a direct bond or an alkylene group having 1 to 4 carbon atoms which may have a substituent. ^R5 to ^R10 each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or a substituted aryl group having 6 to 8 carbon atoms which may have a substituent.
an aryl group having 1 to 15 carbon atoms which may have a substituent; an acyl group having 1 to 10 carbon atoms which may have a substituent; an alkoxy group having 1 to 10 carbon atoms which may have a substituent;
an aryloxy group having 1 to 10 carbon atoms which may have a substituent; an amino group which may have a substituent; a vinyl group having 2 to 10 carbon atoms which may have a substituent;
An ethynyl group having 2 to 10 carbon atoms which may have a substituent, a sulfur atom which has a substituent, a silicon atom which has a substituent, a halogen atom, a nitro group, or a cyano group, provided that R ⁵ to
At least two adjacent groups of R ¹⁰ may be bonded to each other to form a ring.
represents a hydroxy group, a carboxy group, an alkyl ester group having 1 to 10 carbon atoms which may have a substituent, or an aryl ester group having 6 to 15 carbon atoms which may have a substituent.

The structural unit derived from the compound represented by formula (5) not only has excellent physical properties such as heat resistance and photoelastic coefficient, but also can express the so-called reverse wavelength dispersion with high efficiency, that is, the shorter the wavelength, the smaller the retardation, by strictly controlling the content ratio, and can obtain the retardation characteristic close to ideal in a wider wavelength range, especially when used as a quarter wavelength plate, among the uses of optical film.In addition, since the structural unit derived from the compound represented by formula (5) has negative birefringence, it can also be combined with the structural unit derived from the dihydroxy compound (A) having positive birefringence to obtain a polymer with intrinsic birefringence close to zero.

In the compound represented by formula (5), in formula (5), R ³ is particularly preferably an alkylene group having 2 carbon atoms. R ⁴ is particularly preferably an alkylene group having 1 carbon atom. R ⁵ to R ¹⁰ are particularly preferably hydrogen atoms. X is particularly preferably an aryl ester group. By selecting an appropriate structure for each substituent, it is possible to obtain a structural unit having various excellent physical properties such as optical properties, heat resistance, and thermal stability.

The content of the structural unit derived from the compound represented by formula (5) depends on the desired physical properties, but is preferably 1% by weight or more and 70% by weight or less. When reverse wavelength dispersion is desired to be exhibited, the content is preferably 5% by weight or more and 50% by weight or less, and more preferably 10% by weight or more and 30% by weight or less.

[Production method of polycarbonate resin]
The method for producing a polycarbonate resin of the present invention is to continuously supply a dihydroxy compound (A) having an acetal group in a part of its structure, a carbonic acid diester, and a polymerization catalyst to a reactor to carry out a melt polycondensation reaction to produce a polycarbonate resin. The production method of the present invention has at least a raw material preparation step and a polymerization step described below.

Generally, polycarbonate resins can be produced by a variety of polymerization methods. For example, they can be produced by a solution polymerization method using phosgene or a carboxylic acid halide, an interfacial polymerization method, or a melt polymerization method in which a reaction is carried out without using a solvent. In the method of the present invention, the polycarbonate resin is produced by a melt polymerization method. The melt polymerization method does not use a solvent or a highly toxic compound, so that it can reduce the environmental load and is also excellent in productivity.

When producing a resin by melt polymerization, a dihydroxy compound including the dihydroxy compound (A) described above, a carbonic acid diester, and a polymerization catalyst are mixed, and a polycondensation reaction is carried out under molten conditions, and the reaction rate is increased while removing the elimination components from the system. At the end of the polymerization, the reaction is carried out under high temperature and high vacuum conditions until the desired molecular weight is reached. When the reaction is completed, the molten resin is extracted from the reactor, and the polycarbonate resin of the present invention is obtained.

The polycarbonate resin of the present invention can be obtained by polycondensation of a dihydroxy compound containing a dihydroxy compound (A) as an essential component and a carbonic acid diester as raw materials through an ester exchange reaction. As the carbonic acid diester used in the method of the present invention, it is preferable to use a compound represented by the following formula (3).

In formula (3), R ¹ and R ² each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group having 1 carbon atom.
an optionally substituted acyl group having 1 to 10 carbon atoms; an optionally substituted alkoxy group having 1 to 10 carbon atoms; and an optionally substituted alkyl ester group having 1 to 10 carbon atoms.

The optionally substituted alkyl group having 1 to 10 carbon atoms includes a methyl group, an ethyl group,
-Linear alkyl groups such as a n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, and an n-decyl group; an isopropyl group, a 2-methylpropyl group, and a 2,2-dimethylpropyl group;
Examples of the alkyl group include branched alkyl groups such as a 2-ethylhexyl group; and cyclic alkyl groups such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group.

Examples of the optionally substituted acyl group having 1 to 10 carbon atoms include a formyl group, an acetyl group,
aliphatic acyl groups such as propionyl group, 2-methylpropionyl group, 2,2-dimethylpropionyl group, and 2-ethylhexanoyl group;
Examples of the aromatic acyl group include aromatic acyl groups such as 2-naphthylcarbonyl group and 2-furylcarbonyl group.

Examples of the optionally substituted alkoxy group having 1 to 10 carbon atoms include alkoxy groups such as a methoxy group, an ethoxy group, an isopropoxy group, and a t-butoxy group; and acyloxy groups such as an acetoxy group.

Examples of the alkyl ester group having 1 to 10 carbon atoms which may have a substituent include a methyl ester group and an ethyl ester group.

It is more preferable that R ¹ and R ² in formula (3) are each independently a hydrogen atom or an optionally substituted alkyl group having 1 to 10 carbon atoms, in which case reactivity and availability are superior.
Among the carbonate diesters represented by the formula (3), diphenyl carbonate is particularly preferred from the viewpoints of reactivity and availability.

When the carbonic acid diester reacts, a monohydroxy compound is by-produced. When diphenyl carbonate is used as the carbonic acid diester, phenol is by-produced. This monohydroxy compound is preferably recovered and, if necessary, purified by a method such as distillation and reused. In the present invention, the recovered monohydroxy compound phenol is converted into a dihydroxy compound (A) described later.
) can be recycled within the manufacturing process, making it economical.

Polymerization Catalyst The polycondensation reaction proceeds in the presence of an ester exchange reaction catalyst (hereinafter, the ester exchange reaction catalyst is referred to as a "polymerization catalyst"). The type of polymerization catalyst can have a significant effect on the reaction rate of the ester exchange reaction and the quality of the resulting polycarbonate resin.

The polymerization catalyst is not particularly limited as long as it satisfies the transparency, color tone, optical properties, heat resistance, and mechanical properties of the resulting polycarbonate resin. For example, metal compounds of Group I or Group II (hereinafter simply referred to as "Group 1" and "Group 2") in the long-period periodic table, as well as basic compounds such as basic boron compounds, basic phosphorus compounds, basic ammonium compounds, and amine compounds can be used as the polymerization catalyst. Among them, Group 1 metal compounds and/or Group 2 metal compounds are preferred because they have good polymerization activity, good color tone of the resulting polycarbonate resin, and a high effect of inhibiting decomposition of the dihydroxy compound (A).

Examples of Group 1 metal compounds include the following compounds: sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, cesium hydrogen carbonate, sodium carbonate, potassium carbonate, 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 phenylborate, potassium phenylborate, lithium phenylborate, cesium phenylborate, sodium benzoate, potassium benzoate,
Lithium benzoate, cesium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, dicesium hydrogen phosphate, disodium phenylphosphate, dipotassium phenylphosphate, dilithium phenylphosphate, dicesium phenylphosphate, alcoholates and phenolates of sodium, potassium, lithium and cesium, and disodium salt, dipotassium salt, dilithium salt and dicesium salt of bisphenol A, etc. As the Group 1 metal compound, from the viewpoints of polymerization activity and color tone of the obtained polycarbonate resin, lithium compounds are preferred.

Examples of Group 2 metal compounds include the following compounds: 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, and strontium stearate. As the Group 2 metal compound, magnesium compounds, calcium compounds, or barium compounds are preferred, and from the viewpoints of polymerization activity and color tone of the resulting polycarbonate resin, magnesium compounds and/or calcium compounds are more preferred, and calcium compounds are most preferred.

Although it is possible to use a basic compound such as a basic boron compound, a basic phosphorus compound, a basic ammonium compound, or an amine compound in combination with the Group 1 metal compound and/or the Group 2 metal compound, it is more preferable to use only the Group 1 metal compound and/or the Group 2 metal compound, and from the viewpoint of the color tone of the resulting polycarbonate resin, it is most preferable to use only the Group 2 metal compound.

The amount of the polymerization catalyst used was 0.1 mole per mole of the total dihydroxy compounds used in the reaction.
The amount of the polymerization catalyst is preferably 300 μmol or less, more preferably 100 μmol or less, and particularly preferably 50 μmol or less per mol of the total dihydroxy compounds used in the reaction.
By adjusting the amount of the polymerization catalyst used within the above-mentioned range, the polymerization rate can be increased, and therefore it is possible to obtain a polycarbonate resin having a desired molecular weight while keeping the polymerization temperature low and suppressing reactions that lead to quality degradation such as coloration and thermal decomposition.

In the method of the present invention, it is preferable to use the polymerization catalyst also as a stabilizer for the dihydroxy compound (A). Usually, the position of the polymerization catalyst may be anywhere before the polymerization step, but in the method of the present invention, it is preferable to add the polymerization catalyst to a dissolving tank for the dihydroxy compound (A). That is,
In this case, the basic compound used in the dissolving tank of the dihydroxy compound (A) is synonymous with the polymerization catalyst. In this way, the acidic impurities are neutralized by the polymerization catalyst, which is a basic compound, and the decomposition of the dihydroxy compound (A) can be suppressed. A more detailed method will be described later.

In the polycondensation reaction, the reaction rate and the molecular weight of the resulting resin can be controlled by strictly adjusting the molar ratio of all dihydroxy compounds to all diester compounds used in the reaction. In the case of polycarbonate resin, the molar ratio of all diester compounds to all dihydroxy compounds is 0.9
It is preferable to adjust the molar ratio to 0 to 1.10, more preferably 0.95 to 1.05, and particularly preferably 0.97 to 1.03. If the molar ratio is significantly off to the upper or lower limit, it becomes impossible to produce a resin having the desired molecular weight.

The melt polymerization method is usually carried out in a multi-stage process of two or more stages. The polymerization reaction may be carried out in two or more stages using one polymerization reactor by sequentially changing the conditions, or may be carried out in two or more stages using two or more reactors by changing the conditions for each stage. From the viewpoint of production efficiency, it is preferable to carry out the polymerization reaction using two or more reactors, preferably three or more reactors. Generally, the polymerization reaction may be carried out in a batch system, a continuous system, or a combination of a batch system and a continuous system, but in the method of the present invention, a continuous system is used from the viewpoint of production efficiency and stability of quality.

In order to control the reaction rate and the quality of the polycarbonate resin, the melt polycondensation reaction is carried out
The molar ratio of the dihydroxy compound and the diester compound must be strictly controlled. Since it is difficult to obtain the required quantitative accuracy by a method of supplying a solid, the dihydroxy compound or diester compound used as a raw material for the polycarbonate resin is usually handled as a molten liquid in an atmosphere of an inert gas such as nitrogen or argon using a batch, semi-batch, or continuous stirring tank type apparatus.

[Raw material preparation process]
In the production method of the present invention, as a part of a raw material preparation step, the dihydroxy compound (A) is dissolved in a raw material dissolving tank in a solvent containing the monohydroxy compound represented by the formula (1) as a main component.
The method further comprises a step of dissolving the solvent in the solvent (dissolving step), wherein the solvent contains a basic compound.

In the method of the present invention, a solvent containing a monohydroxy compound represented by the following formula (1) as a main component is used as a solvent for the dihydroxy compound (A). This makes it possible to lower the temperature required for dissolving the dihydroxy compound (A) and shorten the time required for dissolution.
The decomposition of the dihydroxy compound can be effectively suppressed. On the other hand, when the dihydroxy compound is melted alone or when an inappropriate solvent is used, high temperatures are required for dissolution, which causes a decomposition reaction of the dihydroxy compound, making it impossible to control the physical properties of the resulting polymer.

In formula (1), R ¹ and R ² each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group having 1 carbon atom.
an optionally substituted acyl group having 1 to 10 carbon atoms; an optionally substituted alkoxy group having 1 to 10 carbon atoms; and an optionally substituted alkyl ester group having 1 to 10 carbon atoms.

The optionally substituted alkyl group having 1 to 10 carbon atoms includes a methyl group, an ethyl group,
-Linear alkyl groups such as a n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, and an n-decyl group; an isopropyl group, a 2-methylpropyl group, and a 2,2-dimethylpropyl group;
Examples of the alkyl group include branched alkyl groups such as a 2-ethylhexyl group; and cyclic alkyl groups such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group.

Examples of the optionally substituted acyl group having 1 to 10 carbon atoms include a formyl group, an acetyl group,
aliphatic acyl groups such as propionyl group, 2-methylpropionyl group, 2,2-dimethylpropionyl group, and 2-ethylhexanoyl group;
Examples of the aromatic acyl group include aromatic acyl groups such as 2-naphthylcarbonyl group and 2-furylcarbonyl group.

Examples of the optionally substituted alkoxy group having 1 to 10 carbon atoms include alkoxy groups such as a methoxy group, an ethoxy group, an isopropoxy group, and a t-butoxy group; and acyloxy groups such as an acetoxy group.

Examples of the alkyl ester group having 1 to 10 carbon atoms which may have a substituent include a methyl ester group and an ethyl ester group.
It is more preferable that R ¹ and R ² in formula (1) are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may be substituted. In this case, reactivity and availability are superior. From the same viewpoint, it is also preferable that R ¹ and R ² are both hydrogen atoms.

From the viewpoint of solubility, the solvent is, with the total weight of the solvent being 100% by weight,
It is preferable that the solvent contains 50% by weight or more, more preferably 70% by weight or more, further preferably 85% by weight or more, and particularly preferably 95% by weight or more of a monohydroxy compound represented by the formula (1). From the viewpoints of improving the polymerization reactivity and the quality of the obtained polycarbonate resin, and being excellent in economic rationality, it is most preferable to use a solvent consisting essentially of a monohydroxy compound represented by the formula (1).

The solvent used in the method of the present invention, which contains a monohydroxy compound represented by the following formula (1) as a main component, may contain compounds other than the monohydroxy compound represented by the following formula (1) as solvent components, but if the solvent contains a large amount of carbonate diester, when moisture is brought into the raw material dissolution tank, the carbonate diester may be hydrolyzed, causing the diester/diol charging molar ratio to fluctuate, making it difficult to control the molecular weight of the resin. Therefore, the weight ratio of the carbonate diester in the solvent is preferably less than 50% by weight, more preferably 10% by weight or less, even more preferably 5% by weight or less, and particularly preferably substantially free of the carbonate diester, taking the total weight of the solvent as 100% by weight.

The monohydroxy compound used as a solvent for the dihydroxy compound (A) is preferably the same compound as the elimination component of the carbonic acid diester described above. When diphenyl carbonate is used as the carbonic acid diester, it is preferable to use phenol as the monohydroxy compound. In this way, the polymerization reactivity and the quality of the obtained polycarbonate resin are not affected, and the dihydroxy compound can be recovered together with the dihydroxy compound by-produced in the polymerization reaction in the step of distilling and purifying the polymerization distillate described later, and can be used repeatedly.

Basic Compound The solvent containing the monohydroxy compound represented by formula (1) as a main component used in the method of the present invention contains a basic compound.
The dihydroxy compound (A) used in the present invention may decompose and generate branched components when handled in a molten state in the raw material preparation process due to the effects of heat and traces of acidic impurities. However, this side effect can be suppressed by including a basic compound in the solvent.

The basic compound is not particularly limited, but examples thereof include compounds of Group I of the long-form periodic table,
Alternatively, metal compounds of Group II (hereinafter simply referred to as "Group 1" and "Group 2"), as well as basic compounds such as basic boron compounds, basic phosphorus compounds, basic ammonium compounds, and amine compounds, can be used. Among these, Group 1 metal compounds and/or Group 2 metal compounds are preferred because of their good polymerization activity, the good color tone of the resulting polycarbonate resin, and their high effect of inhibiting the decomposition of the dihydroxy compound (A).

Examples of Group 1 metal compounds include the following compounds: sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, cesium hydrogen carbonate, sodium carbonate, potassium carbonate, 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 phenylborate, potassium phenylborate, lithium phenylborate, cesium phenylborate, sodium benzoate, potassium benzoate,
Lithium benzoate, cesium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, dicesium hydrogen phosphate, disodium phenylphosphate, dipotassium phenylphosphate, dilithium phenylphosphate, dicesium phenylphosphate, alcoholates and phenolates of sodium, potassium, lithium and cesium, and disodium salt, dipotassium salt, dilithium salt and dicesium salt of bisphenol A, etc. As the Group 1 metal compound, from the viewpoints of polymerization activity and color tone of the obtained polycarbonate resin, lithium compounds are preferred.

Examples of Group 2 metal compounds include the following compounds: 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, and strontium stearate. As the Group 2 metal compound, magnesium compounds, calcium compounds, or barium compounds are preferred, and from the viewpoints of polymerization activity and color tone of the resulting polycarbonate resin, magnesium compounds and/or calcium compounds are more preferred, and calcium compounds are most preferred.

Since the basic compound used in the raw material preparation step is brought directly into the polymerization step, it is preferable to use a compound that does not adversely affect the polymerization reactivity or the resulting polycarbonate resin. Therefore, it is preferable to use the above-mentioned polymerization catalyst as the basic compound. The amount of the basic compound (polymerization catalyst) used in the raw material preparation step depends on the amount of acidic impurities contained in the dihydroxy compound (A), and it is necessary to add an equimolar amount or more to the acidic impurities. In order to completely suppress the decomposition reaction of the dihydroxy compound (A), it is preferable to sufficiently reduce the content of the acidic impurities and then adjust the amount of the basic compound (polymerization catalyst) added to the range of the preferred amount of the polymerization catalyst used.

The raw material preparation step of the method of the present invention may include a step of adding a basic compound to a solvent containing the monohydroxy compound represented by the formula (1) as a main component.
The amount of the basic compound to be added is preferably 0.1 μmol or more, more preferably 0.5 μmol or more, per 1 mol of the total dihydroxy compounds used in the melt polycondensation reaction.
The amount of the basic compound added is preferably 300 μmol or less, more preferably 100 μmol or less, and particularly preferably 50 μmol or less per mol of the total dihydroxy compounds used in the melt polycondensation reaction. By adjusting the amount of the basic compound added to the above range, an excellent effect of suppressing the decomposition of the dihydroxy compound (A) can be exhibited.
The timing of adding the basic compound to the solvent containing the monohydroxy compound represented by the formula (1) as a main component is not particularly limited, and the basic compound may be added before, after, or simultaneously with the addition of the dihydroxy compound (A) to the solvent.
It is preferable to add a basic compound to the solvent before adding the dihydroxy compound (A), in which case the dihydroxy compound (A) comes into contact with the basic compound substantially before heat is applied, and therefore the decomposition suppression effect is greater.

Dissolving step In the method of the present invention, the method of dissolving the dihydroxy compound (A) in a solvent containing the monohydroxy compound represented by the formula (1) as a main component is not particularly limited. For example, a method of melting the monohydroxy compound represented by the following formula (1) in advance, and supplying the solid dihydroxy compound (A) to a raw material dissolving tank having the molten liquid, and dissolving it therein, can be preferably used.

The procedure for dissolving the dihydroxy compound (A) is not particularly limited, but may be, for example,
(A) first, a melt of the monohydroxy compound represented by the formula (1) is charged into a raw material dissolving tank, then a basic compound is charged, and then a dihydroxy compound (A) is charged; and (B) first, a melt of the monohydroxy compound represented by the formula (1) is charged into a raw material dissolving tank,
Next, a procedure may be used in which the dihydroxy compound (A) and the basic compound are added almost simultaneously.
Since the dihydroxy compound (A) decomposes in a very short time when heat is applied, it is preferable to add a basic compound (polymerization catalyst) before introducing the dihydroxy compound (A) into the raw material dissolving tank. Therefore, it is more preferable to adopt the above-mentioned procedure (A).

The internal temperature of the raw material dissolving tank is preferably 150° C. or lower, more preferably 140° C. or lower, while it is preferably 80° C. or higher, more preferably 90° C. or higher. By controlling the internal temperature of the dissolving tank within the above range, the decomposition reaction and coloration of the dihydroxy compound (A) can be suppressed, and the risk of crystallization during transfer, which may cause blockage of piping, etc., can be avoided.

The raw material dissolving tank may be one tank, or two or more tanks may be connected in series. The dihydroxy compound (A) supplied to the first dissolving tank is usually at room temperature, so the temperature required for dissolving the compound is higher than the temperature required to maintain the liquid state. In this case, the dissolved portion continues to be exposed to high temperatures, which makes the compound more susceptible to thermal degradation.
By transferring the dissolved liquid in the first layer to the second tank, the second layer can be maintained at a lower temperature than the first tank.

In the method of the present invention, the polymerization reaction is carried out in a continuous manner. The polymerization reaction is started by continuously supplying the raw material melt and the polymerization catalyst prepared in advance to the reaction tank at a constant flow rate. After the polymerization reaction is started, additional raw materials are periodically added so that the raw material melt does not become empty. In this case, for the dissolving step of the dihydroxy compound (A), if a method is adopted in which the raw material is continuously supplied to the dissolution tank at a constant flow rate and the melt is continuously discharged from the dissolution tank at a constant flow rate, the thermal history related to liquefaction and maintaining the molten state can be minimized and the residence time required for dissolution can be made constant. Although the decomposition of the dihydroxy compound (A) cannot be completely avoided, by keeping the temperature and residence time required for dissolution constant, raw materials of a constant quality can be supplied to the reactor, leading to stabilization of the quality of the polycarbonate obtained. Therefore, it is particularly preferable that the dihydroxy compound (A) is continuously supplied to the raw material dissolution tank and the solution containing the dissolved dihydroxy compound (A) is continuously discharged from the raw material dissolution tank.

In the method for continuously dissolving a dihydroxy compound (A),
The residence time from when the mixture is charged into the dissolution tank until it is fed into the reactor is 0.5 hours or more, and 12
The retention time is preferably 1 hour or less. The upper limit is more preferably 10 hours or less, and particularly preferably 8 hours or less. The lower limit is more preferably 1 hour or more, and particularly preferably 2 hours or more. By setting the retention time within the above range, the decomposition reaction of the dihydroxy compound (A) can be suppressed, and the dissolution of the raw material can be completed in time. In this specification, the retention time in the tank during continuous operation is defined by the following formula.
Residence time [hr] = Tank content [kg] / Discharge amount [kg/hr]

The polymerization catalyst used is usually prepared in advance as an aqueous solution. The concentration of the aqueous catalyst solution is not particularly limited, and is adjusted to an arbitrary concentration depending on the solubility of the catalyst in water.
Other solvents such as acetone, alcohol, toluene, phenol, etc. may also be selected. The nature of the water used to dissolve the polymerization catalyst is not particularly limited as long as the types and concentrations of impurities contained therein are constant, but distilled water, deionized water, etc. are usually preferably used.

In order to suppress thermal deterioration of the raw materials, it is preferable to maintain an inert gas atmosphere such as nitrogen or argon in the equipment for the raw material preparation step and polymerization step. Nitrogen is usually used industrially. When a solid compound is introduced into the equipment, there is a risk that air will be mixed in by being entrained in the solid. Therefore, before introducing the solid dihydroxy compound (A) into the dissolution tank, the inside of the container receiving the dihydroxy compound (A) is depressurized or pressurized to replace the air with an inert gas, or a method of blowing an inert gas into the dissolution tank can be used to prevent air from being mixed in. By the above-mentioned method, it is preferable to maintain the oxygen concentration inside the dissolution tank at 0.5% by volume or less.

In order to prevent contamination of foreign matter originating from the raw materials or from the outside, it is preferable that the molten raw materials are filtered through a filter before being supplied to the reactor. In the present invention, among the raw materials used, any of the raw materials may be filtered, or all of them may be filtered, and the method is not limited. A mixture of all the raw materials may be filtered, or they may be filtered separately and then mixed. In addition, the reaction liquid during the polycondensation reaction may be filtered through a filter. Although a filter may be installed on each raw material line, it is preferable to mix all the raw materials and then pass them through one filter from the viewpoint of simplifying the equipment.

[Polymerization process]
In a polymerization reaction, it is important to properly control the balance between temperature and pressure in the reaction system. If either the temperature or pressure is changed too quickly, unreacted monomers may be distilled out of the reaction system. As a result, the molar ratio of the dihydroxy compound and the diester compound may change, and a resin with the desired molecular weight may not be obtained.

The polymerization rate is controlled by the balance between the hydroxyl group end and the ester group end or carbonate group end. Therefore, particularly when polymerization is performed in a continuous manner, if the balance of the end groups fluctuates due to the distillation of unreacted monomers, it becomes difficult to control the polymerization rate at a constant rate, and there is a risk that the molecular weight of the resulting resin will fluctuate greatly. Since the molecular weight of a resin correlates with the melt viscosity, when the resulting resin is molded, the melt viscosity may fluctuate, leading to problems such as failure to obtain molded products of uniform dimensions.

Furthermore, when unreacted monomers are distilled off, not only the balance of the terminal groups but also the copolymerization composition of the resin deviates from the desired composition, which may affect the mechanical properties and optical properties. Since the optical properties such as birefringence and refractive index of the resin of the present invention are controlled by the ratio of each structural unit in the polycarbonate resin, if the ratio is lost during the polycondensation reaction, the optical properties as designed may not be obtained.

Specifically, the following conditions can be adopted as the reaction conditions in the first stage reaction. That is, the internal temperature of the polymerization reactor is set in the range of usually 130° C. or higher, preferably 150° C. or higher, more preferably 170° C. or higher, and usually 250° C. or lower, preferably 240° C. or lower, more preferably 230° C. or lower. The pressure of the polymerization reactor is usually 70 kPa or lower (
Hereinafter, pressure refers to absolute pressure.), preferably 50 kPa or less, more preferably 30 kPa or less.
Pa or less, and usually 1 kPa or more, preferably 3 kPa or more, more preferably 5 kPa or more
The reaction time is set within the range of usually 0.1 hours or more, preferably 0.5 hours or more, and usually 10 hours or less, preferably 5 hours or less, more preferably 3 hours or less.

The first-stage reaction is carried out while the monohydroxy compound derived from the diester compound generated is distilled out of the reaction system. For example, when diphenyl carbonate is used as the carbonic acid diester, the monohydroxy compound distilled out of the reaction system in the first-stage reaction is phenol.

In the first stage reaction, the lower the reaction pressure, the more the polymerization reaction can be accelerated, but on the other hand, the more unreacted monomer is distilled off.
In order to achieve both the promotion of the reaction by reducing the pressure and the reaction temperature, it is effective to use a reactor equipped with a reflux condenser. The use of a reflux condenser is particularly effective in the early stages of the reaction when there is a large amount of unreacted monomer.

In the second stage reaction, the pressure of the reaction system is gradually lowered from the pressure of the first stage, and the monohydroxy compound generated is subsequently removed from the reaction system, and the pressure of the reaction system is finally lowered to 5 kPa or less, preferably 3 kPa or less, and more preferably 1 kPa or less.
The reaction temperature is set to 10° C. or higher, preferably 220° C. or higher, and usually 260° C. or lower, preferably 250° C. or lower, particularly preferably 240° C. or lower. The reaction time is set to usually 0.1 hours or higher, preferably 0.5 hours or higher, more preferably 1 hour or higher, and usually 10 hours or lower, preferably 5 hours or lower, more preferably 3 hours or lower. In order to suppress coloration and thermal deterioration and obtain a resin with good hue and thermal stability, the maximum internal temperature in all reaction stages is set to 260° C. or lower, preferably 250° C. or lower, more preferably 240° C. or lower.

From the viewpoint of controlling the polymerization rate and the quality of the resulting polycarbonate resin, it is important to appropriately select the jacket temperature, the internal temperature, and the pressure in the reaction system according to the reaction stage. Specifically, it is preferable to obtain a prepolymer at a relatively low temperature and low vacuum in the early stage of the polymerization reaction, and to increase the molecular weight to a predetermined value at a relatively high temperature and high vacuum in the later stage of the reaction. In this case, the distillation of unreacted monomers is suppressed, and it becomes easy to adjust the molar ratio of the dihydroxy compound and the diester compound to a desired ratio. As a result, the decrease in the polymerization rate can be suppressed. In addition, it becomes possible to more reliably obtain a polymer having a desired molecular weight and terminal group.

Once it has been confirmed that the specified melt viscosity (molecular weight) has been reached using the stirring power etc. as an indicator,
The polymerization reaction is stopped by introducing nitrogen into the reactor to return the pressure to normal pressure. In the case of a continuous type, the polymerization reaction is stopped by continuously withdrawing the molten resin from the reactor and cooling it. The molten resin is discharged from the die head in the form of strands, cooled and solidified, and pelletized with a rotary cutter or the like. If necessary, extrusion devolatilization, extrusion kneading, and extrusion filtration processes may be added before pelletization. In these processes, additives are mixed into the resin, low molecular weight components are devolatilized using a vacuum vent, and foreign matter is removed using a polymer filter.

[Analysis of primary polymer structure of polycarbonate resin]
The molecular weight distribution of the polymer can be measured by GPC analysis described later.
When the resulting polycarbonate resin contains a branched structure, the molecular weight distribution increases. The numerical value of the molecular weight distribution varies not only depending on the presence or absence of a branched structure, but also depending on the type and copolymerization ratio of the monomers used and the molecular weight of the polymer, so that the preferable range of the molecular weight distribution of the polycarbonate resin obtained by the method of the present invention cannot be expressed as an absolute value.
As shown in Reference Example 1 described later, it is preferable that the molecular weight distribution of the polymer obtained by a batch process in which raw materials containing a polymerization catalyst are charged all at once to prevent decomposition of the dihydroxy compound (A) is not increased compared to that of a polymer of the same formulation obtained by the polymerization reaction in a batch process.

In addition, when the dihydroxy compound (A) is decomposed, the polymer may be decomposed by the method described later.
When ¹ H-NMR analysis is performed, a peak of a different component derived from a decomposition product of the dihydroxy compound (A) is detected at 5.7 to 5.8 ppm. In the method of the present invention, the content of the different component is 0.05 ppm or less relative to the total amount of structural units derived from the dihydroxy compound (A) in the polymer.
% or less, more preferably 0.03 mol % or less, and
It is particularly preferable that the content is 0.01 mol % or less.

[Additives]
[0043] As long as the effects of the present invention are not impaired, catalyst deactivators, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, release agents, lubricants, fillers such as fillers, antifogging agents, antiblocking agents, colorants, flame retardants, antistatic agents, conductivity imparting agents, crosslinking agents, crosslinking assistants, metal deactivators, molecular weight regulators, antibacterial agents, fluorescent brightening agents, light diffusing agents, and the like may be blended into the polycarbonate resin of the present invention.

In addition, for the purpose of modifying the mechanical properties, solvent resistance, and other properties of the resin, the resin may be kneaded with one or more synthetic resins such as polycarbonate, polyester, polyamide, polystyrene, polyolefin, acrylic, amorphous polyolefin, ABS, AS, and other rubbers to form a polymer alloy.

The additives and modifiers can be produced by mixing the resin of the present invention with the above components simultaneously or in any order using a mixer such as a tumbler, a V-type blender, a Nauter mixer, a Banbury mixer, a kneading roll, an extruder, etc. Among these, kneading with an extruder, particularly a twin-screw extruder, is preferred from the viewpoint of improving dispersibility.

[Recovery of by-products]
The monohydroxy compound by-produced in the polymerization reaction is preferably collected in a tank and, from the viewpoint of effective resource utilization, purified and recovered as necessary and then reused. When the recovered product is phenol, it can be used as a raw material for diphenyl carbonate or bisphenol A. In the method of the present invention, a part of the recovered monohydroxy compound can be reused as a solvent for the dihydroxy compound (A).

In the method of the present invention, the purification method of the by-product monohydroxy compound is not particularly limited, but from the viewpoint of purification efficiency and productivity, it is preferable to use a distillation method. The distillation method may be a batch type or a continuous type, but in the method of the present invention, since the polymerization step is a continuous type and by-products are also continuously generated, it is preferable to carry out the distillation in a continuous type. A single distillation tower may be used, or two or more distillation towers may be used in combination. In the method of the present invention, the monohydroxy compound to be purified contains both components with lower boiling points (water, residual solvent in the raw material, etc.) and components with higher boiling points (unreacted monomers and oligomers), so it is preferable to combine two or more distillation towers and remove the low boiling point components in the first distillation tower and the high boiling point components in the second distillation tower.

[Resin Applications]
The resin of the present invention and a resin composition containing the same can be molded into a molded product by a commonly known method such as injection molding, extrusion molding, compression molding, etc., and a molded product having excellent optical properties, heat resistance, and mechanical strength can be obtained. The resin obtained by the method of the present invention can be made uniform in mechanical properties such as melt viscosity properties and tensile strength by strictly controlling the polymer primary structure, and is therefore particularly suitable for use in retardation films in which melt extrusion film formation and stretching are performed continuously.

The present invention will be described in more detail below using examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

[Measurement method]
Various physical properties were measured according to the following methods.

Reduced Viscosity A resin sample was dissolved in methylene chloride to prepare a resin solution with a concentration of 0.6 g/dL. The measurement was performed at a temperature of 20.0° C.±0.1° C. using an Ubbelohde viscometer manufactured by Moritomo Rika Kogyo Co., Ltd.
The solvent passing time _t0 and the solution passing time t were measured. The obtained values of _t0 and t were used to calculate the relative viscosity η _rel according to the following formula (i), and the obtained relative viscosity η _rel was used to calculate the specific viscosity η _sp according to the following formula (ii).
η _rel =t/t ₀ ...(i)
η _sp = (η-η ₀ )/η ₀ = η _rel -1 (ii)
The specific viscosity η _sp obtained was then divided by the concentration c [g/dL] to obtain the reduced viscosity η _sp /c. The higher this value, the larger the molecular weight.

Molecular weight distribution Approximately 0.1 g of a resin sample was dissolved in 2 mL of methylene chloride, and the solution was filtered through a 0.2 μm disk filter and subjected to GPC measurement. Standard polystyrene was also subjected to GPC measurement in the same manner, and the number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw/Mn) in terms of polystyrene were obtained.
The equipment and conditions were as follows:
Pump: LC-20AD (Shimadzu Corporation)
・Degasser: DGU-20A5 (Shimadzu Corporation)
・Column oven: CTO-20AC (Shimadzu Corporation)
Detector: Differential refractive index detector RID-10A (manufactured by Shimadzu Corporation)
Column: PLgel 10 μm Guard, PLgel 10 μm MIXED-B
2 (Agilent)
Oven temperature: 40°C
Eluent: chloroform Flow rate: 1 mL/min
Injection volume: 10 μL

^1H -NMR
Approximately 15 mg of a polycarbonate resin sample was weighed out, dissolved in approximately 0.7 mL of deuterated chloroform, and placed in an NMR tube with an inner diameter of 5 mm to measure the ¹ H-NMR spectrum.
The content [mol %] of the heterogeneous structure was calculated from the intensity ratio of the signal of the heterogeneous structure (decomposition product of SPG) detected at 5.7 to 5.8 ppm. The apparatus and conditions used are as follows.
・Device: JNM-ECZ400S (manufactured by JEOL Ltd.)
Measurement temperature: 30°C
Relaxation time: 6 seconds Accumulation times: 64

The method for calculating the content of heterogeneous structures will be described below using the polycarbonate resins produced in the Examples and Comparative Examples as examples.
Range for calculating integral value (a): 5.7 to 5.8 ppm: derived from heterogeneous structure (number of protons: 1)
(b): 2.4 to 2.0 ppm: derived from BPFM repeating structural unit (number of protons: 4)
(c): 1.5 to 0.5 ppm: SPG repeating unit (proton number: 12) and BPF
Calculation of the amount of heterogeneous structures relative to the total amount of M repeating structural units (proton number: 4) and SPG repeating structural units (a)/{(c)-(b)}/12×100 [mol %]

Resin performance evaluation After the resin pellets were vacuum-dried at 100 ° C. for 6 hours or more, a film-making device equipped with a single-screw extruder (manufactured by Technovel Co., Ltd., screw diameter 25 mm, cylinder set temperature: 240 ° C.), a T-die (width 400 mm, set temperature: 250 ° C.), a chill roll (set temperature: 120 to 130 ° C.), and a winder was used to produce an unstretched film with a width of 300 mm and a thickness of 100 μm. A film piece with a length of 70 mm and a width of 100 mm was cut out from this film, and the free end was uniaxially stretched using a batch-type biaxial stretching device (Island Industrial Co., Ltd. BIX-277-AL) to obtain a stretched film. The stretching conditions were an oven set temperature of 150 ° C., a stretching speed of 300% / min, and a stretching ratio of 2 times. If stretching was successful under these conditions, the stretching ratio was set to 2
The stretching ratio was gradually increased to 1x, 2.2x, and so on, and the film was repeatedly stretched until it reached the stretching ratio at which it broke.

Among the films stretched by the above method, the center of the stretched film obtained at the maximum stretch ratio was cut to a width of 2 mm.
The specimen was cut into pieces of 2 cm length and 2 cm length, and a phase difference measuring device (KOBRA-WPR manufactured by Oji Scientific Instruments) was used.
Using the above, measurement wavelengths were 446.3 nm, 498.0 nm, 547.9 nm, and 585.9 nm.
The phase difference was measured at 590 nm (R590
) and the film thickness at the measurement position, the birefringence (Δn) was calculated from the following formula:
Birefringence=R590 [nm]/(film thickness [mm]×10 ⁶ )

[Ingredients used]
The abbreviations and manufacturers of the compounds used in the following Examples and Production Examples are as follows.

[monomer]
SPG: Spiroglycol (manufactured by Mitsubishi Gas Chemical Company, Inc.)
・ISB: Isosorbide (manufactured by Rocket Fleuret)
BPFM: Bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane. Synthesized by the method described in JP-A-2015-25111.

DPC: Diphenyl carbonate (manufactured by Mitsubishi Chemical Corporation)
PHL: Phenol (manufactured by Mitsubishi Chemical Corporation)
[Polymerization catalyst]
Calcium acetate monohydrate (Kanto Chemical)
Calcium acetate monohydrate was dissolved in demineralized water to prepare an aqueous solution of a given concentration.
[Catalyst deactivator]
- Phosphonic acid (Tokyo Chemical Industry Co., Ltd.)
[Heat stabilizer (antioxidant)]
Irganox 1010: Pentaerythritol-tetrakis(3-(3,5-di-t
tert-Butyl-4-hydroxyphenyl)propionate (manufactured by BASF)

Example 1
A polycarbonate resin was produced using the polymerization equipment A shown in FIG. 1 and FIG. 3. PHL and an aqueous catalyst solution were supplied to the SPG dissolution tank 1j for a residence time of 7 hours. The amount of catalyst was supplied so that it was 12 μmol per 1 mol of the dihydroxy compound used in the polymerization. Next, SPG was supplied for a residence time of 7 hours. ISB was charged from the flexible container 2a to the ISB dissolution tank 2b, and the overflowing molten liquid was transferred to the molten ISB tank 2d. 229.7 parts by weight of molten DPC and 100 parts by weight of PBFM were supplied to the raw material dissolution tank 3d from the flexible container 3a, and after dissolution, they were transferred to the raw material storage tank 3f. The metering pumps (1k, 2d, 3g) for each raw material were started simultaneously at a predetermined set flow rate, and the raw material molten liquid was supplied to the first vertical reactor 21a, and polymerization was started. At the same time, the SPG constant-volume feeder 1e, the PHL constant-volume supply pump 1g, and the aqueous catalyst solution constant-volume supply pump 1i also started supplying at the specified set flow rates. The PBFM, DPC, and ISB periodically supplied additional raw materials to the raw material storage tanks so that they would not become empty.

The flow rate of each metering pump and the operating conditions of each raw material dissolving tank were set as follows:
・SPG (1e): 30.2 parts by weight/hr
・PHL (1g): 24.7 parts by weight/hr
・SPG/PHL mixed liquid (1k): 54.8 parts by weight/hr
・ISB (2d): 40.0 parts by weight/hr
・PBFM/DPC mixed liquid (3g): 99.3 parts by weight/hr
Internal temperature of raw material dissolving tank 1j: 125° C., residence time: 7 hours

The molar ratio and weight ratio of each structural unit in the resulting polycarbonate resin are as follows: SPG/ISB/PBFM/DPC=0.266/0.734/0.126/0.87
4 (molar ratio), SPG/ISB/PBFM/DPC=30.0/39.5/21.4/
9.1% by weight.

The liquid level was kept constant while controlling the opening of the valve installed in the transfer pipe at the bottom of the reactor so that the average residence time in the first vertical stirring reactor was 90 minutes. The reaction liquid discharged from the bottom of the reactor was then continuously supplied to the second vertical stirring reactor, the third vertical stirring reactor, and the fourth horizontal stirring reactor in succession. The first vertical stirring reactor and the second vertical stirring reactor were equipped with reflux condensers to suppress the distillation of unreacted monomers.

The reaction temperature, internal pressure, and residence time of each reactor were as follows: First vertical stirred reactor: 195°C, 2
7 kPa, 90 min, 2nd vertical stirred reactor: 205°C, 20 kPa, 90 min, 3rd vertical stirred reactor: 220°C, 10 kPa, 60 min, 4th horizontal stirred reactor: 235°C, 1 kPa, 1
The polymerization rate was controlled by the degree of vacuum in the fourth horizontal stirred reactor, and the reactor was operated while adjusting the reduced viscosity of the resulting polycarbonate resin to be 0.45 dL/g to 0.47 dL/g.

The resin discharged from the fourth horizontal stirring reactor was then fed in a vented twin-screw extruder in a molten state. The polycarbonate resin passing through the extruder was filtered to remove foreign matter through a 10 μm Ultipleat candle-type filter (manufactured by Pall) in a molten state. The resin was then discharged in the form of strands from the die, cooled with water, solidified, and pelletized with a rotary cutter to obtain a polycarbonate resin.

The extruder had three vacuum vents, where residual low molecular weight components in the resin were removed by volatilization. 2000 ppm by weight of water was added to the resin before the second vent, and water injection volatilization was performed. 0.1 parts by weight of Irganox 1010 was added to 100 parts by weight of polycarbonate resin before the third vent.

The phenol by-produced in the polymerization reaction is collected in a distillate tank 23a and then fed to a distillation column 23c.
The phenol was purified by removing low-boiling impurities (mainly water) and heavy-boiling impurities (mainly monomers and oligomers) in the phenol melting tank 23f. The purified phenol was returned to the molten PHL tank 1f and used again in the raw material preparation process.

The operation was carried out under the above-mentioned operating conditions for two consecutive days, and pellets were sampled every two hours. The molecular weight distribution of the pellets was measured by GPC, and was found to be 2.4 to 2.5, with no variation in the polymer primary structure. No heterogeneous structures were detected by ¹ H-NMR analysis. The samples with the smallest and largest molecular weight distributions were selected from the obtained samples,
The film was evaluated for stretching by the above-mentioned method, and a stable high stretch ratio and high orientation were obtained. The evaluation results are shown in Table 1.

(Comparative Example 1)
In Example 1, the aqueous catalyst solution was not added to the raw material dissolver 1j, but was added immediately before the first reactor using the aqueous catalyst solution constant-feed pump 4d. The rest was the same as in Example 1.
The molecular weight distribution of the obtained polycarbonate resin was 4.0 to 5.7, which was wider and more varied than that of Example 1. ¹ H-NMR analysis detected 0.25 mol % of a heterogeneous structure. In the film stretching evaluation, both the stretch ratio and the orientation were significantly lower than those of Example 1, and the variations were also larger.

Example 2
A polycarbonate resin was produced using the polymerization equipment B shown in Figures 2 and 3. PHL, DPC, and an aqueous catalyst solution were supplied to the raw material dissolution tank 11g for a residence time of 5 hours. After stirring for 10 minutes, PBFM and SPG were supplied for a residence time of 5 hours. After all the raw materials were dissolved, the raw material mixture was transferred to the raw material storage tank 11h. The ISB was transferred from the flexible container 12a to the I
The SB dissolving tank 12b was charged with the raw materials, and the molten liquid was transferred to the molten ISB tank 12d. The metering pumps (11i, 12e) for each raw material were simultaneously started at a predetermined set flow rate, and the first vertical reactor 21a
The raw material melt was fed to the raw material storage tank to start polymerization. After that, additional raw materials were periodically fed to each raw material storage tank so that they would not become empty.

The flow rate of each metering pump and the operating conditions of each raw material dissolving tank were set as follows:
・SPG・PHL・PBFM・DPC mixed liquid (11i): 154.1 parts by weight/hr
・ISB (12e): 40.0 parts by weight/hr
Internal temperature of raw material dissolving tank 11h: 125°C

The polymerization process was carried out in the same manner as in Example 1. The molecular weight distribution of the obtained polycarbonate resin was 2.
The molecular weight distribution ranged from 0.4 to 2.7, which was a slightly larger variation in molecular weight distribution compared to Example 1. In the film stretching evaluation, both the stretch ratio and orientation were slightly lower than in Example 1. The reason for the broadening of the molecular weight distribution is thought to be that the step of dissolving SPG was a batch process, and a distribution occurred in the thermal history received by SPG in the dissolving step, which resulted in a corresponding variation in the amount of decomposition products of SPG.

(Comparative Example 2)
In Example 2, the aqueous catalyst solution was not added to the raw material dissolving tank 11g, but was added immediately before the first reactor using the aqueous catalyst solution constant-feed pump 13d. Other than that, the procedure was the same as in Example 1. The molecular weight distribution of the obtained polycarbonate resin was 2.9 to 3.8, which was wider and had a larger degree of variation than in Examples 1 and 2. In the stretching evaluation of the film, both the stretch ratio and the orientation were significantly lower and had a larger variation than in Examples 1 and 2.

(Comparative Example 3)
In Example 2, the raw materials were mixed in a raw material dissolving tank (11 g) without using PHL. The internal temperature was raised to 170° C. to completely dissolve SPG. The rest was the same as in Example 1. The molecular weight distribution of the obtained polycarbonate resin was 2.6 to 3.0, and the molecular weight distribution was wider and the degree of variation was larger than those in Examples 1 and 2. In the stretching evaluation of the film, both the stretch ratio and the orientation were lower than those in Examples 1 and 2.

(Reference Example 1)
A polycarbonate resin was produced using a batch-type polymerization equipment C (not shown) equipped with a stirring blade and a reflux condenser.
G, ISB, PBFM, DPC, and calcium acetate monohydrate were mixed in a molar ratio of SPG/I
SB/PBFM/DPC=0.266/0.734/0.126/0.874/12×1
^0-6 , SPG/ISB/PBFM/DPC=30.2/40.0/30.1/ by weight
After thoroughly replacing the inside of the reactor with nitrogen, the reactor was heated with a heat medium.
Stirring was started when the internal temperature reached 100°C. 40 minutes after the start of temperature rise, the internal temperature was allowed to reach 220°C, and while controlling to maintain this temperature, pressure reduction was started at the same time, and the pressure was reduced to 13.3 kPa in 90 minutes after reaching 220°C. Phenol vapor by-produced during the polymerization reaction was led to a reflux condenser, and a small amount of monomer components contained in the phenol vapor were returned to the reactor, and the uncondensed phenol vapor was subsequently led to a condenser at 45°C and recovered. Next, the internal temperature was raised to 240°C over 30 minutes, and the internal pressure was raised to 1 kPa. Thereafter, the pressure was lowered to 133 Pa or less over 30 minutes, and the pressure was restored when the predetermined stirring power was reached, and the contents were extracted in the form of strands and pelletized with a rotary cutter. The molecular weight distribution of the obtained polycarbonate resin was 2.5, which was comparable to that of Example 1. No heterogeneous structure was detected in the ¹ H-NMR analysis. In the stretching evaluation of the film, a high stretch ratio and high orientation were obtained similar to those of Example 1. It is clear that decomposition of SPG and an increase in molecular weight distribution can be suppressed by contacting the SPG with a basic compound before dissolving it by heating.

Figure 1. Polymerization equipment A raw material preparation process 1a: SPG flexible container 1b: SPG receiving hopper 1c: SPG air blower 1d: SPG raw material silo 1e: SPG metering feeder 1f: Molten PHL tank 1g: PHL quantitative supply pump 1h: Catalyst aqueous solution tank 1i: Catalyst aqueous solution quantitative supply pump 1j: SPG/PHL raw material dissolution tank 1k: SPG/PHL quantitative supply pump 2a: ISB flexible container 2b: ISB dissolution tank 2c: ISB storage tank 2d: ISB quantitative supply pump 3a: PBFM flexible container 3b: Molten DPC tank 3c: DPC quantitative emergency pump 3d: PBFM/DPC raw material dissolution tank 3e: Transfer pump 3f: PBFM/DPC storage tank 3g: PBFM/DPC quantitative supply pump 4a: Static mixer 4b: Filter 4c: Catalyst aqueous solution tank 4d: Catalyst aqueous solution quantitative supply pump

FIG. 2 Raw material preparation process of polymerization equipment B 11a: SPG flexible container 11b: PBFM flexible container 11c: Molten PHL tank 11d: PHL metered supply pump 11e: Molten DPC tank 11f: DPC metered supply pump 11g: SPG, PBFM, DPC, PHL raw material dissolution tank 11h: SPG, PBFM, DPC, PHL storage tank 11i: SPG, PBFM, DPC, PHL metered supply pump 12a: ISB flexible container 12b: ISB dissolution tank 12c: Transfer pump 12d: ISB storage tank 12e: ISB metered supply pump 13a: Static mixer 13b: Filter 13c: Catalyst aqueous solution tank 13d: Catalyst aqueous solution metered supply pump

Figure 3 Polymerization process and distillation process (common to both polymerization equipment A and B)
21a: First vertical stirring reactor 21b: Reflux condenser 21c: Second vertical stirring reactor 21d: Reflux condenser 21e: Third vertical stirring reactor 21f: Gear pump 21g: Fourth horizontal stirring reactor 21h: Gear pump 22a: Vacuum vent type twin screw extruder 22b: Gear pump 22c: Polymer filter 22d: Die 23a: Distillate recovery tank 23b: Distillate metering pump 23c: First distillation column 23d: metering pump 23e: Reflux condenser 23f: Second distillation column 23g: metering pump 23h: Reflux condenser

Claims (11)

A method for producing a polycarbonate resin, comprising continuously supplying a dihydroxy compound (A) having an acetal group as a part of its structure, a carbonic acid diester, and a polymerization catalyst to a reactor to carry out a melt polycondensation reaction, comprising the steps of:
The method includes a step of dissolving the dihydroxy compound (A) in a solvent containing a monohydroxy compound represented by the following formula (1) as a main component in a raw material dissolving tank,
The method for producing a polycarbonate resin is characterized in that the solvent has a lower melting point than the dihydroxy compound (A) and contains a basic compound.

(R ¹ and R ² in formula (1) are each independently a hydrogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, an optionally substituted acyl group having 1 to 10 carbon atoms, an optionally substituted alkoxy group having 1 to 10 carbon atoms, or an optionally substituted alkyl ester group having 1 to 10 carbon atoms.) The method for producing polycarbonate resin according to claim 1, wherein the internal temperature of the raw material dissolving tank is 80°C or higher and 150°C or lower. The method for producing a polycarbonate resin according to claim 1 or 2, wherein the dihydroxy compound (A) is continuously supplied to the raw material dissolving tank, and a solution containing the dissolved dihydroxy compound (A) is continuously discharged from the raw material dissolving tank. The method for producing a polycarbonate resin according to any one of claims 1 to 3, wherein the dihydroxy compound (A) is a compound represented by the following formula (2):

The method for producing a polycarbonate resin according to any one of claims ^{1 to 4, wherein a content of a component detected at 5.7 to 5.8 ppm in a 1H} -NMR spectrum of the polycarbonate resin measured using a deuterated chloroform solvent is 0.05 mol% or less based on a total amount of structural units derived from the compound represented by formula (2). The method for producing a polycarbonate resin according to any one of claims 1 to 5, wherein the basic compound is at least one metal compound selected from the group consisting of metals in Group 2 of the long form periodic table and lithium. The method for producing a polycarbonate resin according to any one of claims 1 to 6, wherein the content of the basic compound in the solvent is 0.1 μmol or more and 50 μmol or less per 1 mol of the total dihydroxy compounds used in the melt polycondensation reaction. The method for producing a polycarbonate resin according to any one of claims 1 to 7, wherein the carbonate diester is a compound represented by the following formula (3):

(R ¹ and R ² in formula (3) each independently represent a hydrogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, an optionally substituted acyl group having 1 to 10 carbon atoms, an optionally substituted alkoxy group having 1 to 10 carbon atoms, or an optionally substituted alkyl ester group having 1 to 10 carbon atoms.) 9. The method for producing a polycarbonate resin according to claim 8, further comprising a step of recovering a monohydroxy compound produced as a by-product in the polycondensation reaction and purifying the recovered monohydroxy compound by distillation, and the distilled and purified monohydroxy compound is supplied to the raw material dissolving tank . The method for producing a polycarbonate resin according to any one of claims 1 to 9, wherein the polycarbonate resin contains a structural unit derived from a dihydroxy compound represented by the following formula (4):

The method for producing a polycarbonate resin according to any one of claims 1 to 10, wherein the polycarbonate resin contains a structural unit derived from a compound represented by the following formula (5):

(In formula (5), R ³ and R ⁴ are each independently a direct bond or an alkylene group having 1 to 4 carbon atoms which may have a substituent. R ⁵ to R ¹⁰ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 6 to 15 carbon atoms which may have a substituent, an acyl group having 1 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, an aryloxy group having 6 to 15 carbon atoms which may have a substituent, an acyloxy group having 1 to 10 carbon atoms which may have a substituent, an amino group which may have a substituent, a vinyl group having 2 to 10 carbon atoms which may have a substituent, an ethynyl group having 2 to 10 carbon atoms which may have a substituent, a sulfur atom which has a substituent, a silicon atom which has a substituent, a halogen atom, a nitro group, or a cyano group. However, R ⁵ to R At least two adjacent groups among ¹⁰ may be bonded to each other to form a ring. X is a hydroxy group, a carboxy group, an alkyl ester group having 1 to 10 carbon atoms which may have a substituent, or an aryl ester group having 6 to 15 carbon atoms which may have a substituent.

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