JP6565577B2 - Polycarbonate resin and optical film comprising the same - Google Patents

Description

  The present invention relates to a polycarbonate resin excellent in optical properties, heat resistance and melt processability, and an optical film comprising the same.

  In recent years, the demand for transparent resins used for optical applications such as optical lenses, optical films, and optical recording media has increased. Among them, thin flat panel displays (FPDs) represented by liquid crystal displays and organic EL displays are particularly widespread, improving display quality such as improving contrast and coloring, widening the viewing angle, and preventing external light reflection. Various optical films have been developed and used for the purpose.

Cycloolefin polymers such as ZEONOR (registered trademark) of Nippon Zeon Co., Ltd. and Arton (registered trademark) of JSR Co., Ltd. are used in retardation films for FPDs due to their excellent optical properties. . These cycloolefin polymers have a characteristic that the wavelength dispersion (wavelength dependence) of retardation is flat, and are suitably used for broadband wavelength plates (see, for example, Non-Patent Document 1 and Patent Document 1).
Conventional polycarbonate resins have been mainly used with bisphenol A as a monomer, but in recent years, polycarbonate resins having isosorbide (ISB) as a monomer component have been developed. Polycarbonate resins using ISB are excellent in various properties such as heat resistance and optical properties, and are being studied for use in optical applications such as retardation films and glass substitute applications (see, for example, Patent Documents 2 and 3). ). In addition, ISB is a dihydroxy compound obtained from biomass resources, and is also interested in being a carbon-neutral material that does not contribute to an increase in carbon dioxide emissions even when incinerated.

  As a method for arbitrarily adjusting the wavelength dispersion of the phase difference, a polymer in which a monomer having a conjugated structure such as fluorene in the side chain is copolymerized has been developed. The present inventors have disclosed polycarbonates and polyester carbonates having divalent fluorene as a repeating structural unit, and resin compositions that are suitably used for λ / 4 plates have been studied (see Patent Document 4).

JP 2004-198478 A Japanese Patent No. 5346449 JP 2012-214666 A Japanese Patent Laying-Open No. 2015-25111

ZEON Co., Ltd., “ZEONOR Technical Report 1 High-performance optical material ZEONOR film”, [online], date unknown, [searched on September 15, 2015], Internet <http://www.zeon.co.jp /business/enterprise/speplast/optes2.html〉

In the use of a retardation film (stretched film), in addition to further improvements in optical properties and quality, there are also demands for improvement in productivity and cost reduction in each process such as film formation, stretching, and lamination. Thinning the film or improving the draw ratio greatly contributes to cost reduction and productivity improvement, so the resin used as the film material must first have characteristics such as toughness and melt processability. Is done. Furthermore, it is also important to consider a molecular design so that large birefringence is exhibited by stretching, that is, the intrinsic (extreme) birefringence is large.

  In recent years, optical film properties such as retardation films do not change the optical properties and dimensions of the film in processes involving heating during polarizing plate and display assembly processes and in high-temperature and high-humidity environments. In addition, there is a demand for improving the heat resistance of the material. At the same time, there is also a demand that the viscosity can be controlled to an appropriate viscosity at an appropriate temperature so as to facilitate processing when forming into a film. Furthermore, there is also a demand for a small change in optical properties due to the expansion and contraction of the film due to a change in use environment. It is necessary to devise material design so as to balance these various physical properties.

  The object of the present invention is to solve the above-mentioned various problems and to provide a polycarbonate resin excellent in various properties such as heat resistance, optical properties, mechanical properties and melt processability, and a flat wavelength dispersion of the retardation formed therefrom. It is to provide an optical film.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a resin composition containing a polymer having a specific divalent oligofluorene as a repeating unit and having specific optical properties has physical properties. The inventors have found that the object of exhibiting excellent optical properties and excellent mechanical properties when formed into a film can be achieved, and the present invention has been achieved.
That is, the gist of the present invention is as follows.
[1] When the structural unit represented by the following formula (1) or (2) is contained and the total amount of all the structural units and the linking group is 100% by weight, the following formula (1) ) Or (2) is a polycarbonate resin containing 1% by weight or more and 18% by weight or less of the structural unit represented by the drawing film, and a stretched film prepared from the polycarbonate resin has a retardation (R450) at a wavelength of 450 nm. A polycarbonate resin having a ratio (R450 / R550) to a phase difference (R550) at a wavelength of 550 nm of 0.98 or more and 1.01 or less.

(In Formula (1) and (2), R < ¹ > -R < ³ > is a C1-C4 alkylene group which may have a direct bond and a substituent each independently, R < ⁴ > -R < ⁹ >. Each independently has a hydrogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, an optionally substituted aryl group having 4 to 10 carbon atoms, and a substituent. An optionally substituted acyl group having 1 to 10 carbon atoms, 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 optionally substituted acyloxy group having 1 to 10 carbon atoms, an amino group optionally having substituents, a vinyl group having 1 to 10 carbon atoms optionally having substituents, and a substituent An ethynyl group having 1 to 10 carbon atoms, a sulfur atom having a substituent, and a silicon having a substituent. Atom, a halogen atom, a nitro group, or a cyano group. However, they may form a ring adjacent the at least two groups are bonded to each other among the R ⁴ to R ^9.)
[2] When the total amount of all the structural units constituting the polycarbonate resin and the weight of the linking group is 100% by weight, the structural unit represented by the following formula (3) is 10% by weight or more and 75% by weight. The polycarbonate resin according to [1], which is contained below.

[3] When the total amount of all the structural units constituting the polycarbonate resin and the weight of the linking group is 100% by weight, an aliphatic dihydroxy compound, an alicyclic dihydroxy compound, a dihydroxy compound containing an acetal ring, oxy The polycarbonate resin according to [1] or [2], which contains 0.1 wt% or more and 60 wt% or less of a structural unit derived from at least one compound selected from alkylene glycol and aromatic dihydroxy compounds.
[4] When the total amount of all the structural units constituting the polycarbonate resin and the weight of the linking group is 100% by weight, the structural unit derived from the aromatic compound is contained in an amount of 25% by weight or less. 3] The polycarbonate resin according to any one of the above.
[5] A transparent film formed by molding the polycarbonate resin according to any one of [1] to [4].
[6] The transparent film according to [5], which is formed by a melt film forming method at a forming temperature of 280 ° C. or less.
[7] A retardation film obtained by stretching the film according to [5] or [6] in at least one direction.

  When the polycarbonate resin of the present invention is formed into a film, it exhibits excellent optical properties, and even when the proportion in the resin is low, the use of a repeating unit that efficiently expresses desired optical properties allows the degree of freedom in resin design. And has various physical properties such as heat resistance, melt processability and mechanical strength, it is useful as a material for optical applications, particularly for retardation films.

  DESCRIPTION OF EMBODIMENTS Embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention is as follows unless it exceeds the gist. The content is not limited. In the present invention, the “structural unit” means a partial structure sandwiched between adjacent linking groups in the polymer, a polymerization reactive group present at the terminal portion of the polymer, and the polymerization reactive group. A partial structure sandwiched between matching linking groups. The linking group means a carbonate bond portion (carbonate group) and an ester bond portion (ester group).

In the present invention, the polycarbonate resin includes a polyester carbonate resin. The polyester carbonate resin refers to a polycarbonate resin in which a structural unit constituting the resin includes not only a carbonate bond but also a portion connected by an ester bond.
The present invention is a polycarbonate resin containing a structural unit represented by the following formula (1) or (2), wherein the total amount of all the structural units constituting the polycarbonate resin and the weight of the linking group is 100%. % Of the structural unit represented by the following formula (1) or (2) in an amount of not less than 1% by weight and not more than 18% by weight of a stretched film prepared from the polycarbonate resin at a wavelength of 450 nm. The polycarbonate resin has a value of chromatic dispersion (R450 / R550), which is a ratio of (R450) to a phase difference (R550) at a wavelength of 550 nm, of 0.98 or more and 1.01 or less.

(In Formula (1) and (2), R < ¹ > -R < ³ > is a C1-C4 alkylene group which may have a direct bond and a substituent each independently, R < ⁴ > -R < ⁹ >. Each independently has a hydrogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, an optionally substituted aryl group having 4 to 10 carbon atoms, and a substituent. An optionally substituted acyl group having 1 to 10 carbon atoms, 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 optionally substituted acyloxy group having 1 to 10 carbon atoms, an amino group optionally having substituents, a vinyl group having 1 to 10 carbon atoms optionally having substituents, and a substituent An ethynyl group having 1 to 10 carbon atoms, a sulfur atom having a substituent, and a silicon having a substituent. Atom, a halogen atom, a nitro group, or a cyano group. However, they may form a ring adjacent the at least two groups are bonded to each other among the R ⁴ to R ^9.)

  The upper limit of the content of the structural unit represented by the formula (1) or (2) is more preferably 16% by weight or less, and particularly preferably 14% by weight or less. When the content of the structural unit represented by the formula (1) or (2) is larger than the above range, the orientation birefringence is lowered, and the high orientation which is the object of the present invention cannot be obtained, or the photoelastic coefficient. The optical properties such as Further, the lower limit of the content of the structural unit represented by the formula (1) or (2) is more preferably 2% by weight or more, and particularly preferably 3% by weight or more. When the content of the structural unit represented by the formula (1) or (2) is smaller than the above range, the wavelength dispersion cannot be adjusted to a desired range.

When the value of chromatic dispersion (R450 / R550) is larger than the above range, optical compensation over a wide wavelength range becomes impossible, making it difficult to apply to the use of a retardation film requiring a wide band property. In addition, when the value of wavelength dispersion (R450 / R550) is smaller than the above range, the orientation birefringence is lowered by lowering the intrinsic birefringence of the polycarbonate resin. It becomes difficult to apply.

[Structure and raw materials of polycarbonate resin]
(Oligofluorene structural unit)
The polycarbonate resin of the present invention contains a structural unit selected from structural units represented by the following formula (1) or (2). The structural units represented by the following formulas (1) and (2) may be referred to as “oligofluorene structural units”.

(In Formula (1) and (2), R < ¹ > -R < ³ > is a C1-C4 alkylene group which may have a direct bond and a substituent each independently, R < ⁴ > -R < ⁹ >. Each independently has a hydrogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, an optionally substituted aryl group having 4 to 10 carbon atoms, and a substituent. An optionally substituted acyl group having 1 to 10 carbon atoms, 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 optionally substituted acyloxy group having 1 to 10 carbon atoms, an amino group optionally having substituents, a vinyl group having 1 to 10 carbon atoms optionally having substituents, and a substituent An ethynyl group having 1 to 10 carbon atoms, a sulfur atom having a substituent, and a silicon having a substituent. Atom, a halogen atom, a nitro group, or a cyano group. However, they may form a ring adjacent the at least two groups are bonded to each other among the R ⁴ to R ^9.)

  By introducing these structural units, it becomes possible to adjust the wavelength dispersion (wavelength dependence) of the phase difference. Many polymers have a positive wavelength dispersion in which the phase difference is increased as the wavelength is shorter, but the structural unit represented by the above formulas (1) and (2) has an inverse wavelength where the phase difference is decreased as the wavelength is shorter. Since it has dispersibility, it can be adjusted from flat wavelength dispersibility to reverse wavelength dispersibility according to the content of the structural units represented by the formulas (1) and (2) in the polycarbonate resin. it can.

In order to develop optimum wavelength dispersion characteristics and high orientation as a retardation film having flat dispersibility, which is the object of the present invention, the inclusion of structural units represented by the above formulas (1) and (2) When the total amount of all the structural units constituting the polycarbonate resin and the weight of the linking group is 100% by weight, the upper limit is 18% by weight or less, preferably 16% by weight or less, and 14% by weight or less. Is particularly preferred. On the other hand, the content of the structural units represented by the formulas (1) and (2) is lower when the total weight of all the structural units constituting the polycarbonate resin and the linking group is 100% by weight. The content is preferably 1% by weight or more, more preferably 2% by weight or more, and particularly preferably 3% by weight or more.

  Since the structural units represented by the formulas (1) and (2) have negative intrinsic birefringence, the content of the structural units represented by the formulas (1) and (2) in the polycarbonate resin Is larger than the above range, the birefringence of the polycarbonate resin becomes too small, and the desired phase difference may not be obtained. Moreover, since the ratio of other copolymerization components decreases, it becomes difficult to adjust the balance of other properties such as heat resistance and mechanical properties. On the other hand, when the content of the structural unit represented by the formulas (1) and (2) in the polycarbonate resin is less than the lower limit, a desired retardation may not be obtained.

In R ¹ and R ² in the above formulas (1) and (2), as the “optionally substituted alkylene group having 1 to 4 carbon atoms”, for example, the following alkylene groups may be employed. it can.
Linear alkylene group such as methylene group, ethylene group, n-propylene group, n-butylene group; methylmethylene group, dimethylmethylene group, ethylmethylene group, propylmethylene group, (1-methylethyl) methylene group, 1 -Methylethylene group, 2-methylethylene group, 1-ethylethylene group, 2-ethylethylene group, 1-methylpropylene group, 2-methylpropylene group, 1,1-dimethylethylene group, 2,2-dimethylpropylene group An alkylene group having a branched chain, such as 3-methylpropylene group. Here, the position of the branched chain in R ¹ and R ² is indicated by a number assigned so that the carbon on the fluorene ring side is in the first position.

The selection of R ¹ and R ² has a particularly important influence on the development of reverse wavelength dispersion. In the state where the fluorene ring in the oligofluorene structural unit is oriented perpendicular to the main chain direction (stretching direction), the strongest reverse wavelength dispersion is exhibited. In order to bring the orientation state of the fluorene ring closer to the above state and to exhibit strong reverse wavelength dispersion, it is preferable to employ R ¹ and R ² having ² to 3 carbon atoms on the main chain of the alkylene group. . When the number of carbon atoms is 1, surprisingly, reverse wavelength dispersion may not be exhibited. This may be because the orientation of the fluorene ring is fixed in a direction that is not perpendicular to the main chain direction due to the steric hindrance of the carbonate group or ester group that is the linking group of the oligofluorene structural unit. . On the other hand, when the number of carbon atoms is too large, the reverse wavelength dispersibility may be weakened due to weak fixation of the orientation of the fluorene ring. In addition, the heat resistance of the resin tends to decrease.

As shown in the formulas (1) and (2), R ¹ and R ² are either an oxygen atom in which one end of an alkylene group is bonded to a fluorene ring and the other end is an oxygen atom or carbonyl carbon contained in the linking group. Are connected. From the viewpoints of thermal stability, heat resistance, and reverse wavelength dispersion, it is preferable that the other end of the alkylene group is bonded to the carbonyl carbon. As will be described later, as the monomer having an oligofluorene structure, specifically, a diol or diester structure (hereinafter, the diester also includes a dicarboxylic acid) can be considered, but polymerization is preferably performed using the diester as a raw material. Further, from the viewpoint of facilitating production, it is preferable to employ the same alkylene group for R ¹ and R ² .

In R ³ , as the “optionally substituted alkylene group having 1 to 4 carbon atoms”, for example, the following alkylene groups can be employed.
Linear alkylene group such as methylene group, ethylene group, n-propylene group, n-butylene group; methylmethylene group, dimethylmethylene group, ethylmethylene group, propylmethylene group,
(1-methylethyl) methylene group, 1-methylethylene group, 2-methylethylene group, 1-ethylethylene group, 2-ethylethylene group, 1-methylpropylene group, 2-methylpropylene group, 1,1-dimethyl An alkylene group having a branched chain such as an ethylene group, a 2,2-dimethylpropylene group, and a 3-methylpropylene group;

R ³ preferably has 1 to 2 carbon atoms on the main chain of the alkylene group, and particularly preferably 1 carbon atom. When R ³ having too many carbons on the main chain is adopted, the fixation of the fluorene ring is weakened similarly to R ¹ and R ² , the reverse wavelength dispersion is decreased, the photoelastic coefficient is increased, and the heat resistance is decreased. Etc. may be caused. On the other hand, the smaller the number of carbons on the main chain, the better the optical properties and heat resistance, but the thermal stability deteriorates when the 9-positions of the two fluorene rings are connected by a direct bond.

The fluorene ring contained in the oligofluorene structural unit has a configuration in which all of R ^{4 to} R ⁹ are hydrogen atoms, or R ⁴ and / or R ⁹ are halogen atoms, acyl groups, nitro groups, cyano groups, and sulfo groups. It is preferably any one selected from the group consisting of groups, and any structure in which R ^{5 to} R ⁸ are hydrogen atoms. In the case of having the former configuration, the compound containing the oligofluorene structural unit can be derived from fluorene which is industrially inexpensive. Further, in the case of having the latter configuration, the reactivity at the 9th position of fluorene is improved, so that various induction reactions tend to be adaptable in the process of synthesizing the compound containing the oligofluorene structural unit. The fluorene ring is more preferably selected from the group in which all of R ^{4 to} R ⁹ are hydrogen atoms, or R ⁴ and / or R ⁹ are selected from the group consisting of a fluorine atom, a chlorine atom, a bromine atom, and a nitro group. It is more preferable that R ^{5 to} R ⁸ are any of hydrogen atoms, and a structure in which all of R ^{4 to} R ⁹ are hydrogen atoms is particularly preferable. By adopting the above-described configuration, the fluorene ratio can be increased, steric hindrance between fluorene rings hardly occurs, and desired optical characteristics derived from the fluorene ring tend to be obtained.

Among the divalent oligofluorene structural units represented by the above formulas (1) and (2), preferred structures include structures having a skeleton specifically exemplified in the following group [A].
[A]

  Examples of the monomer having an oligofluorene structural unit include a specific dihydroxy compound represented by the following formula (4) and a specific diester represented by the following formula (5).

(Formula (4) and (5) ^in, R 1 to R ⁹ may have the ^R 1 identical .A ¹ and ^{A 2} and to R ⁹ is a hydrogen atom, or each substituent of the formula (1) and (2) An aliphatic hydrocarbon group having 1 to 18 carbon atoms which may be substituted, or an aromatic hydrocarbon group which may have a substituent, and A ¹ and A ² may be the same or different. May be good.)

  As the monomer having a divalent oligofluorene structural unit, it is particularly preferable to use a specific diester represented by the formula (5). The specific diester has relatively better thermal stability than the specific dihydroxy compound represented by the formula (4), and the fluorene ring in the polymer is oriented in a preferred direction, resulting in stronger reverse wavelength dispersion. There is a tendency to show sex. When the polycarbonate resin contains a diester structural unit, the resin is referred to as a polyester carbonate resin.

When A ¹ and A ^{2 in} the formula (5) are a hydrogen atom or an aliphatic hydrocarbon group such as a methyl group or an ethyl group, the polymerization reaction may hardly occur under the polymerization conditions of the polycarbonate usually used. is there. Therefore, A ¹ and A ^{2 in} the formula (5) are preferably aromatic hydrocarbon groups.

(Dihydroxy compound)
The polycarbonate resin of the present invention preferably contains a structural unit represented by the following formula (3).

  The content of the structural unit represented by the formula (3) is 75% by weight or less as an upper limit when the total amount of all the structural units constituting the polycarbonate resin and the weight of the linking group is 100% by weight. Preferably, 72 weight% or less is more preferable, and 70 weight% or less is especially preferable. When the content of the structural unit represented by the formula (3) is larger than the above range, heat resistance becomes excessively high, and mechanical properties and melt processability are deteriorated. In addition, since the structural unit represented by the formula (3) has a highly hygroscopic structure, when the content is excessively large, the water absorption of the polycarbonate resin is high, and the molded product has a high moisture content. There is a concern that optical physical properties may change or deformation or cracking may occur. On the other hand, the content of the structural unit represented by the formula (3) is 10% by weight as a lower limit when the total amount of all the structural units constituting the polycarbonate resin and the weight of the linking group is 100% by weight. The above is preferable, 15% by weight or more is more preferable, and 20% by weight or more is particularly preferable. When the content of the structural unit represented by the formula (3) is smaller than the above range, heat resistance may be insufficient, or optical characteristics such as high transmittance and low photoelastic coefficient, which are features, may not be obtained. To do.

  Examples of the dihydroxy compound into which the structural unit represented by the formula (3) can be introduced include isosorbide (ISB), isomannide, and isoide which are in a stereoisomeric relationship. These may be used individually by 1 type and may be used in combination of 2 or more type. Among these, it is most preferable to use ISB from the viewpoint of availability and polymerization reactivity. In addition, the dihydroxy compound containing the structural unit of the formula (3) may be referred to as “dihydroxy compound A”.

The dihydroxy compound A may contain a stabilizer such as a reducing agent, antioxidant, oxygen scavenger, light stabilizer, antacid, pH stabilizer or heat stabilizer. In particular, since the dihydroxy compound B is easily altered under acidic conditions, it is preferable to include a basic stabilizer.
Examples of the basic stabilizer include hydroxides, carbonates, phosphates, phosphites, hypophosphites of group 1 or group 2 metals in the long-period periodic table (Nomenclature of Inorganic Chemistry IUPAC Recommendations 2005). Acid salts, borates and fatty acid salts; tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethylethylammonium hydroxide, trimethylbenzylammonium hydroxide, trimethylphenylammonium hydroxide, Triethylmethylammonium hydroxide, triethylbenzylammonium hydroxide, triethylphenylammonium Basic ammonium compounds such as droxide, tributylbenzylammonium hydroxide, tributylphenylammonium hydroxide, tetraphenylammonium hydroxide, benzyltriphenylammonium hydroxide, methyltriphenylammonium hydroxide and butyltriphenylammonium hydroxide; diethylamine, di Butylamine, triethylamine, morpholine, N-methylmorpholine, pyrrolidine, piperidine, 3-amino-1-propanol, ethylenediamine, N-methyldiethanolamine, diethylethanolamine, diethanolamine, triethanolamine, 4-aminopyridine, 2-aminopyridine, N, N-dimethyl-4-aminopyridine, 4-diethylaminopyridine, 2 -Hydroxypyridine, 2-methoxypyridine, 4-methoxypyridine, 2-dimethylaminoimidazole, 2-methoxyimidazole, imidazole, 2-mercaptoimidazole, 2-methylimidazole, aminoquinoline and the like; amine compounds, and di- (tert -Butyl) amine and hindered amine compounds such as 2,2,6,6-tetramethylpiperidine.

The content of these basic stabilizers in the dihydroxy compound A is not particularly limited, but since the dihydroxy compound B is unstable in an acidic state, the pH of the aqueous solution of the dihydroxy compound A containing the stabilizer is around 7. It is preferable to add a stabilizer.
If the amount of the stabilizer is too small, the effect of preventing the alteration of the dihydroxy compound A may not be obtained. If the amount is too large, the modification of the dihydroxy compound A may be caused. The content is preferably 0001 to 0.1% by weight, more preferably 0.001 to 0.05% by weight.

In addition, since the dihydroxy compound A is easy to absorb moisture and is gradually oxidized by oxygen, it should not be mixed with moisture during handling during storage or manufacturing. Or the like.
In the polycarbonate resin of the present invention, structural units other than the structural units described above may be included (hereinafter sometimes referred to as “other structural units”), and the monomer containing the other structural units includes: Examples include aliphatic dihydroxy compounds, alicyclic dihydroxy compounds, dihydroxy compounds containing an acetal ring, oxyalkylene glycols, dihydroxy compounds containing aromatic components, diester compounds, and the like.

As the aliphatic dihydroxy compound, for example, the following dihydroxy compounds can be used.
Ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 1,5-heptanediol, 1,6-hexane Dihydroxy compounds of linear aliphatic hydrocarbons such as diol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol; dihydroxy compounds of branched aliphatic hydrocarbons such as neopentyl glycol and hexylene glycol Compound.

As the alicyclic dihydroxy compound, for example, the following dihydroxy compounds can be used.
1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, pentacyclopentadecane dimethanol, 2,6-decalin dimethanol, 1,5-decalindi Examples thereof include dihydroxy compounds derived from terpene compounds such as methanol, 2,3-decalin dimethanol, 2,3-norbornane dimethanol, 2,5-norbornane dimethanol, 1,3-adamantane dimethanol and limonene. Dihydroxy compounds which are primary alcohols of alicyclic hydrocarbons; 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,3-adamantanediol, hydrogenated bisphenol A, 2,2,4,4-tetra Methyl-1,3-cyclobutane Illustrated in Lumpur like, dihydroxy compound which is a secondary alcohol and tertiary alcohol alicyclic hydrocarbon.

  Examples of the dihydroxy compound containing an acetal ring include spiroglycol represented by the following structural formula (6), dioxane glycol represented by the following structural formula (7), and inositol represented by the following structural formula (8). Induced dihydroxy compounds and the like can be used.

(In the above formula (8), R ¹⁰ and R ¹¹ each independently represents an organic group having 1 to 30 carbon atoms. These organic groups may have an arbitrary substituent.)
In the formula (8), R ¹⁰ and R ¹¹ are preferably an organic group having 1 to 30 carbon atoms which may have a substituent. Examples of the organic group having 1 to 30 carbon atoms of R ¹⁰ and R ¹¹ include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, Alkyl groups such as dodecyl group, cycloalkyl groups such as cyclopentyl group and cyclohexyl group, linear or branched chain alkenyl groups such as vinyl group, propenyl group and hexenyl group, cyclic alkenyl groups such as cyclopentenyl group and cyclohexenyl group Alkynyl groups such as ethynyl group, methylethynyl group, 1-propionyl group, aryl groups such as phenyl group, naphthyl group, toluyl group, alkoxyphenyl groups such as methoxyphenyl group, aralkyl groups such as benzyl group, phenylethyl group, Heterocyclic groups such as thienyl group, pyridyl group, furyl group and the like can be mentioned. Among these, from the viewpoint of the stability of the polymer itself, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and the like are preferable. From the viewpoint of the balance between the optical characteristics and weather resistance of the polymer, heat resistance and mechanical properties, the alkyl group A cycloalkyl group is particularly preferred.

As the oxyalkylene glycols, for example, the following dihydroxy compounds can be used. Diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, polypropylene glycol.
As the dihydroxy compound containing an aromatic component, for example, the following dihydroxy compounds can be used. 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-nitro Phenyl) methane, 3,3-bis (4-hydroxyphenyl) pentane, 1,3-bis (2- (4-hydroxyphenyl) -2-propyl) benzene, 1,3-bis (2- (4-hydroxy) Phenyl) -2-propyl) benzene, 2,2-bis (4-hydroxyphenyl) hexafluoropropane, 1,1-bis (4-hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl) sulfone, 2,4 ′ -Dihydroxydiphenylsulfone, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxy 3-methylphenyl) sulfide, bis (4-hydroxyphenyl) disulfide, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxy-3,3′-dichlorodiphenyl ether, 6,6′-dihydroxy-3,3 3 ′, 3′-tetramethyl-1,1′-spirobiindane, 7,7′-dimethyl-6,6′-dihydroxy-3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, 9,9-bis (4-hydroxy-3-phenylphenyl) fluorene, 9,9 -Aromatic bisphenol compounds such as bis (2-hydroxynaphthyl) fluorene; 2,2-bis (4- (2-hydroxyethoxy) phenyl Propane, 2,2-bis (4- (2-hydroxypropoxy) phenyl) propane, 1,3-bis (2-hydroxyethoxy) benzene, 4,4′-bis (2-hydroxyethoxy) biphenyl, bis (4 -(2-hydroxyethoxy) phenyl) sulfone, 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-phenylphenyl) fluorene A dihydroxy compound having an ether group bonded to an aromatic group such as 9,9-bis (2- (2-hydroxyethoxy) naphthyl) fluorene.

  As the diester compound, for example, the following dicarboxylic acids can be used. Terephthalic acid, phthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-benzophenone dicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, 4,4 '-Diphenylsulfone dicarboxylic acid, aromatic dicarboxylic acid such as 2,6-naphthalenedicarboxylic acid; 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, decalin-2,6 -Alicyclic dicarboxylic acids such as dicarboxylic acids; aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and the like. These dicarboxylic acid components can be used as raw materials for polyester carbonate as the dicarboxylic acid itself, but depending on the production method, dicarboxylic acid esters such as methyl ester and phenyl ester, and dicarboxylic acids such as dicarboxylic acid halides. Derivatives can also be used as raw materials.

  From the viewpoint of optical properties, it is preferable to use the other structural units listed above that do not contain an aromatic component, but with other physical properties such as heat resistance and mechanical properties while ensuring optical properties. In order to balance, it may be effective to incorporate an aromatic component into the main chain or side chain of the polymer. In this case, for example, an aromatic component can be introduced into the polymer by the other structural unit containing an aromatic structure, but in the present invention, all of the oligofluorene structural units in the polycarbonate resin are also included. The content of the structural unit derived from the aromatic compound (hereinafter also referred to as aromatic structural unit) is 100% by weight when the total weight of all the structural units constituting the polycarbonate resin and the weight of the linking group is 100% by weight. It is preferably 25% by weight or less. When the amount of the structural unit containing an aromatic structure other than the oligofluorene structural unit is increased, the photoelastic coefficient may be deteriorated.

  Monomers having other structural units listed above include 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, spiroglycol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, It is particularly preferred to use 1,4-cyclohexanedicarboxylic acid, decalin-2,6-dicarboxylic acid (and its derivatives). For the purpose of improving the heat resistance while satisfying the optical properties of the obtained polycarbonate resin, 6,6′-dihydroxy-3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane and It is particularly preferable to use a dihydroxy compound derived from inositol represented by the formula (8). Polycarbonate resins containing structural units derived from these monomers have an excellent balance of optical properties, heat resistance, mechanical properties, and the like.

Since the polymerization reactivity of the diester compound is relatively low, it is more preferable not to use a diester compound other than the diester compound having an oligofluorene structural unit from the viewpoint of increasing the reaction efficiency.
Dihydroxy compounds and diester compounds for introducing other structural units may be used singly or in combination of two or more, depending on the required performance of the obtained polycarbonate resin. The content of other structural units in the polycarbonate resin is preferably 0.1% by weight or more as a lower limit when the total amount of all the structural units constituting the polycarbonate resin and the weight of the linking group is 100% by weight. 1% by weight or more is more preferable, and 3% by weight or more is particularly preferable. On the other hand, the content of other structural units in the polycarbonate resin is preferably 60% by weight or less as the upper limit when the total amount of all the structural units constituting the polycarbonate resin and the weight of the linking group is 100% by weight. 50% by weight or less is more preferable, and 40% by weight or less is particularly preferable. Other structural units mainly play a role in adjusting the heat resistance of the polycarbonate resin and imparting flexibility and toughness. If the content is too small, the mechanical properties and melt processability of the polycarbonate resin will deteriorate. When there is too much, there exists a possibility that heat resistance and an optical characteristic may deteriorate.

(Carbonated diester)
The linking group of the structural unit contained in the polycarbonate resin of the present invention is introduced by polymerizing a carbonic acid diester represented by the following formula (9).

(In Formula (9), A ³ and A ⁴ are each an aliphatic hydrocarbon group having 1 to 18 carbon atoms which may have a substituent, or an aromatic hydrocarbon which may have a substituent. And A ³ and A ⁴ may be the same or different.)
A ³ and A ⁴ are preferably a substituted or unsubstituted aromatic hydrocarbon group, and more preferably an unsubstituted aromatic hydrocarbon group. In addition, examples of the substituent of the aliphatic hydrocarbon group include an ester group, an ether group, a carboxylic acid, an amide group, and a halogen. Examples of the substituent of the aromatic hydrocarbon group include an alkyl group such as a methyl group and an ethyl group. Is mentioned.

  Examples of the carbonic acid diester represented by the formula (9) include diphenyl carbonate (hereinafter sometimes abbreviated as DPC), substituted diphenyl carbonate such as ditolyl carbonate, dimethyl carbonate, diethyl carbonate, and di-tert-. Dialkyl carbonates such as butyl carbonate are exemplified, but preferred are diphenyl carbonate and substituted diphenyl carbonate, and particularly preferred is diphenyl carbonate.

Carbonic acid diesters may contain impurities such as chloride ions, which may inhibit the polymerization reaction or worsen the hue of the resulting polycarbonate resin. Is preferably used.
Further, when the above equation (5) polymerized using both the diester monomers the formula carbonic acid diester represented by the (9) represented by reaction, A ^1, A ² and the of the formula (5) When A ³ and A ^{4 in} formula (9) all have the same structure, the components that are eliminated during the polymerization reaction are the same, and the components can be easily recovered and reused. From the viewpoint of usefulness in the polymerization reaction and reuse, it is particularly preferred A ¹ to A ⁴ is a phenyl group. When A ^{1 to} A ⁴ are phenyl groups, the component that is eliminated during the polymerization reaction is phenol.

[Production conditions for polycarbonate resin]
The polycarbonate resin of the present invention can be produced by a generally used polymerization method. For example, it can be produced using a solution polymerization method or an interfacial polymerization method using phosgene or a carboxylic acid halide, or a melt polymerization method in which a reaction is performed without using a solvent. Among these production methods, it is preferable to produce by a melt polymerization method that can reduce environmental burden because it does not use a solvent or a highly toxic compound, and is excellent in productivity.

When a solvent is used for polymerization, the solvent may remain in the polycarbonate resin, and the glass transition temperature of the polycarbonate resin is lowered due to its plasticizing effect, which causes quality fluctuations in processing steps such as molding and stretching described later. obtain. In addition, a halogen-based organic solvent such as methylene chloride is often used as the solvent. However, when the halogen-based solvent remains in the polycarbonate resin, if the molded body using this resin is incorporated into an electronic device or the like, a metal is used. It can also cause corrosion of parts. Since the polycarbonate resin obtained by the melt polymerization method does not contain a solvent, it is advantageous for stabilization of processing steps and product quality.

  When producing a polycarbonate resin by the melt polymerization method, the monomer having the above-mentioned structural unit, a carbonic acid diester, and a polymerization catalyst are mixed and subjected to an ester exchange reaction (also referred to as a polycondensation reaction) under melting. The reaction rate is increased while removing the desorbed components out of the system. At the end of the polymerization, the reaction proceeds to the target molecular weight under conditions of high temperature and high vacuum. When the reaction is completed, the molten polycarbonate resin is withdrawn from the reactor, and the polycarbonate resin of the present invention is obtained.

  In the polycondensation reaction, the reaction rate and the molecular weight of the resulting polycarbonate resin can be controlled by strictly adjusting the molar ratio of all dihydroxy compounds and all diester compounds used in the reaction. In the case of polycarbonate resin, the molar ratio of carbonic acid diester to the total dihydroxy compound is preferably adjusted to 0.90 to 1.10, more preferably 0.96 to 1.05, and 0.98 to 1 It is particularly preferable to adjust to 0.03. In the case of polyester carbonate resin, it is preferable to adjust the molar ratio of the total amount of carbonic diester and all diester compounds to all dihydroxy compounds to 0.90 to 1.10, and 0.96 to 1.05. It is more preferable to adjust to 0.98 to 1.03.

  If the molar ratio deviates greatly in the vertical direction, a resin having a desired molecular weight cannot be produced. Moreover, when the said molar ratio becomes small too much, the hydroxyl-group terminal of manufactured resin will increase and the thermal stability of resin may deteriorate. In addition, a large amount of unreacted dihydroxy compound remains in the polycarbonate resin, which may cause dirt on the molding machine and poor appearance of the molded product in the subsequent molding process. On the other hand, if the molar ratio becomes too large, the transesterification rate decreases under the same conditions, or the residual amount of carbonic diester or diester compound in the produced polycarbonate resin increases. Residual low molecular weight components can also cause problems in the molding process as well.

  The melt polymerization method is usually performed in a multistage process of two or more stages. The polycondensation reaction may be carried out in two or more steps by changing the conditions sequentially using one polymerization reactor, or two or more steps by changing the respective conditions using two or more reactors. However, from the viewpoint of production efficiency, it is carried out using two or more, preferably three or more reactors. The polycondensation reaction may be any of a batch system, a continuous system, or a combination of a batch system and a continuous system, but a continuous system is preferred from the viewpoint of production efficiency and quality stability.

In the polycondensation reaction, it is important to appropriately control the balance between temperature and pressure in the reaction system. If either one of the temperature and 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 changes, and a polycarbonate resin having a desired molecular weight may not be obtained.
In addition, the polymerization rate of the polycondensation reaction is controlled by the balance between the hydroxy group end and the ester group end or carbonate group end. Therefore, particularly when performing polymerization in a continuous manner, if the balance of the end groups varies due to distillation of unreacted monomers, it becomes difficult to control the polymerization rate to be constant, and the variation in the molecular weight of the resulting polycarbonate resin increases. There is a fear. Since the molecular weight of the polycarbonate resin correlates with the melt viscosity, when the obtained polycarbonate resin is molded, there is a possibility that the melt viscosity fluctuates and a molded product having a uniform dimension cannot be obtained.

Further, when the unreacted monomer is distilled, not only the balance of the end groups but also the copolymer composition of the polycarbonate resin may be out of the desired composition, which may affect the mechanical properties and optical characteristics. In the retardation film of the present invention, the wavelength dispersion of retardation is controlled by the ratio of the fluorene monomer in the polycarbonate resin and other copolymerization components. There is a risk that characteristics may not be obtained.

Hereinafter, the process of the melt polycondensation reaction will be described by dividing it into a stage in which monomers are consumed to produce oligomers and a stage in which polymerization is advanced to a desired molecular weight to produce polymers.
Specifically, the following conditions can be adopted as reaction conditions in the first stage reaction. That is, the internal temperature of the polymerization reactor is 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. Set. The pressure in the polymerization reactor is usually 70 kPa or less (hereinafter, pressure represents an absolute pressure), preferably 50 kPa or less, more preferably 30 kPa or less, and usually 1 kPa or more, preferably 3 kPa or more, more preferably. Set in the range of 5 kPa or more. The reaction time is usually set in the range of 0.1 hour or longer, preferably 0.5 hour or longer, and usually 10 hours or shorter, preferably 5 hours or shorter, more preferably 3 hours or shorter.

The first-stage reaction is carried out while distilling out the generated monohydroxy compound derived from the diester compound to the outside 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 promoted. On the other hand, the unreacted monomer is increased in distillation. In order to achieve both suppression of distillation of unreacted monomer and promotion of reaction by reduced pressure, it is effective to use a reactor equipped with a reflux condenser. In particular, it is preferable to use a reflux condenser at the beginning of the reaction with a large amount of unreacted monomers.

  In the second stage reaction, the pressure of the reaction system is gradually decreased from the pressure of the first stage, and the monohydroxy compound generated subsequently is removed from the reaction system. Preferably it is 3 kPa or less, more preferably 1 kPa or less. The internal temperature is usually set in the range of 210 ° C. or higher, preferably 220 ° C. or higher, and usually 270 ° C. or lower, preferably 260 ° C. or lower. The reaction time is usually 0.1 hours or longer, preferably 0.5 hours or longer, more preferably 1 hour or longer, and usually 10 hours or shorter, preferably 5 hours or shorter, more preferably 3 hours or shorter. Set. In order to suppress coloration and thermal deterioration and obtain a polycarbonate resin having good hue and thermal stability, the maximum internal temperature in all reaction stages is 270 ° C. or lower, preferably 265 ° C. or lower, more preferably 260 ° C. or lower. Good.

  The transesterification catalyst that can be used at the time of polymerization (hereinafter sometimes simply referred to as catalyst or polymerization catalyst) has a very large influence on the reaction rate and the color tone and thermal stability of the polycarbonate resin obtained by polycondensation. obtain. The catalyst used is not limited as long as it can satisfy the transparency, hue, heat resistance, thermal stability, and mechanical strength of the produced polycarbonate resin. Examples include basic compounds such as metal compounds of group (hereinafter simply referred to as “Group 1” and “Group 2”), basic boron compounds, basic phosphorus compounds, basic ammonium compounds, and amine compounds. Preferably, at least one metal compound selected from the group consisting of a metal of Group 2 of the long-period periodic table and lithium is used.

As the group 1 metal compound, for example, the following compounds can be employed, but other group 1 metal compounds can also be employed. Sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, sodium bicarbonate, potassium bicarbonate, lithium bicarbonate, cesium bicarbonate, 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 tetraphenylborate, tetraphenyl Potassium borate, lithium tetraphenylborate, cesium tetraphenylborate, sodium benzoate, potassium benzoate, lithium benzoate, cesium benzoate, disodium hydrogen phosphate, hydrogen phosphate Potassium, 2 lithium hydrogen phosphate, 2 cesium hydrogen phosphate, 2 sodium phenyl phosphate, 2 potassium phenyl phosphate, 2 lithium phenyl phosphate, 2 cesium phenyl phosphate, sodium, potassium, lithium, cesium alcoholate, pheno Rate, disodium salt of bisphenol A, 2 potassium salt, 2 lithium salt, 2 cesium salt. Among these, it is preferable to use a lithium compound from the viewpoint of polymerization activity and the hue of the obtained polycarbonate resin.

  As the group 2 metal compound, for example, the following compounds can be employed, but other group 2 metal compounds can also be employed. Calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium bicarbonate, barium bicarbonate, magnesium bicarbonate, strontium bicarbonate, calcium carbonate, barium carbonate, magnesium carbonate, strontium carbonate, calcium acetate, barium acetate, Magnesium acetate, strontium acetate, calcium stearate, barium stearate, magnesium stearate, strontium stearate. Among these, it is preferable to use a magnesium compound, a calcium compound, and a barium compound. From the viewpoint of polymerization activity and the hue of the obtained polycarbonate resin, it is more preferable to use a magnesium compound and / or a calcium compound, and to use a calcium compound. Is most preferred.

In addition, it is also possible to use a basic compound such as a basic boron compound, a basic phosphorus compound, a basic ammonium compound, and an amine compound in combination with the above-mentioned Group 1 metal compound and / or Group 2 metal compound. However, it is particularly preferable to use at least one metal compound selected from the group consisting of a metal of Group 2 of the long-period periodic table and lithium.
The amount of the polymerization catalyst used is usually 0.1 μmol to 300 μmol, preferably 0.5 μmol to 100 μmol, per 1 mol of all dihydroxy compounds used in the polymerization. As the polymerization catalyst, when using at least one metal compound selected from the group consisting of metals of Group 2 of the long-period periodic table and lithium, particularly when using a magnesium compound and / or a calcium compound, the amount of metal is The polymerization catalyst is usually used in an amount of 0.1 μmol or more, preferably 0.3 μmol or more, particularly preferably 0.5 μmol or more, per 1 mol of the total dihydroxy compound. The amount of the polymerization catalyst used is preferably 30 μmol or less, preferably 20 μmol or less, particularly preferably 10 μmol or less.

  In addition, when a polyester carbonate resin is produced using a diester compound as a monomer, a titanium compound, a tin compound, a germanium compound, an antimony compound, a zirconium compound, lead, with or without the use of the basic compound. A transesterification catalyst such as a compound, an osmium compound, a zinc compound, or a manganese compound can also be used. The amount of these transesterification catalysts used is usually in the range of 1 μmol to 1 mmol, preferably in the range of 5 μmol to 800 μmol, particularly preferably in terms of the amount of metal relative to 1 mol of all dihydroxy compounds used in the reaction. It is 10 μmol to 500 μmol.

If the amount of the catalyst is too small, the polymerization rate is slowed down. Therefore, in order to obtain a polycarbonate resin having a desired molecular weight, the polymerization temperature must be increased accordingly. Therefore, there is a high possibility that the hue of the resulting polycarbonate resin will deteriorate, and the unreacted raw material will volatilize during the polymerization, and the molar ratio of the dihydroxy compound and the diester compound may collapse, and the desired molecular weight may not be reached. There is sex. On the other hand, if the amount of the polymerization catalyst used is too large, undesirable side reactions may occur, which may lead to deterioration of the hue of the obtained polycarbonate resin and coloring or decomposition of the polycarbonate resin during molding.

  Among the group 1 metals, sodium, potassium, and cesium may adversely affect the hue when contained in the polycarbonate resin. And these metals may mix not only from the catalyst to be used but from a raw material or a reaction apparatus. Regardless of the source, the total amount of these metal compounds in the polycarbonate resin is preferably 2 μmol or less, preferably 1 μmol or less, more preferably 0.5 μmol or less, per 1 mol of the total dihydroxy compound as the metal amount.

  After the polycarbonate polycarbonate resin of the present invention is polymerized as described above, it is usually cooled and solidified, and pelletized with a rotary cutter or the like. The method of pelletization is not limited, but it is extracted from the final stage polymerization reactor in a molten state, cooled and solidified in the form of a strand and pelletized, uniaxially or in a molten state from the final stage polymerization reactor. A method of supplying polycarbonate resin to a twin-screw extruder, melt-extruding, and then cooling and solidifying to pelletize, or extracting from the final stage polymerization reactor in a molten state, cooling and solidifying in the form of a strand, and then pelletizing Examples thereof include a method in which a polycarbonate resin is supplied again to a single-screw or twin-screw extruder, melt-extruded, cooled and solidified, and pelletized.

  Since the polycarbonate resin of the present invention is suitably used for optical applications, it is preferable that the polycarbonate resin contains little foreign matter. In order to remove foreign matters such as burns and gels in the polycarbonate resin obtained by melt polycondensation, it is preferable to perform filtration using a filter. Among them, after removing residual monomers and by-product phenol by vacuum devolatilization and mixing polycarbonate resin with the above vent type twin screw extruder to mix additives such as heat stabilizer and mold release agent It is preferable to filter with a filter.

  As a form of this filter, a known type such as a candle type, a pleat type, a leaf disk type, or the like can be used. The opening of the filter is preferably 50 μm or less, more preferably 40 μm or less, and still more preferably 20 μm or less as 99% filtration accuracy. When it is desired to reduce foreign matter, the filter aperture is preferably 10 μm or less. However, if the aperture is small, the pressure loss in the filter increases and the filter is damaged or the polycarbonate resin deteriorates due to shearing heat generation. Therefore, it is preferable that the filtration accuracy of 99% is 1 μm or more. The aperture of the filter referred to here is determined in accordance with ISO16889.

  The polycarbonate resin filtered by the filter is discharged from the die head in the form of a strand, cooled and solidified, and pelletized by a rotary cutter or the like. Is preferably performed in a clean room having a higher degree of cleanliness than Class 7, more preferably Class 6 defined in JIS B 9920 (2002), in order to prevent foreign matter from entering from outside air.

  When pelletizing, it is preferable to use a cooling method such as air cooling or water cooling. The air used for air cooling is air obtained by removing foreign substances in the air in advance with a hepa filter or the like. It is desirable to prevent reattachment of foreign matter inside. When using water cooling, it is desirable to use water from which metal in water has been removed with an ion exchange polycarbonate resin or the like, and further, foreign matter in water has been removed with a water filter. The aperture of the water filter to be used is preferably 10 to 0.45 μm as the filtration accuracy for 99% removal.

[Preferable physical properties of polycarbonate resin]
The molecular weight of the polycarbonate resin of the present invention thus obtained can be represented by reduced viscosity. If the reduced viscosity of the polycarbonate resin is too low, the mechanical strength of the molded product may be reduced. Therefore, the reduced viscosity is usually 0.20 dL / g or more, and preferably 0.25 dL / g or more. On the other hand, when the reduced viscosity of the polycarbonate resin is too large, the fluidity at the time of molding decreases, and the productivity and moldability tend to decrease. Therefore, the reduced viscosity is usually 0.80 dL / g or less, preferably 0.70 dL / g or less, and more preferably 0.60 dL / g or less. The reduced viscosity is precisely adjusted to a sample concentration of 0.6 g / dL using a methylene chloride as a solvent as detailed in the Examples section, and the Ubbelohde viscosity at a temperature of 20.0 ° C. ± 0.1 ° C. Measure using a meter.

  Since the reduced viscosity has a correlation with the melt viscosity of the polycarbonate resin, the stirring power of the polymerization reactor, the discharge pressure of the gear pump that transfers the melted polycarbonate resin, and the like can usually be used as indicators for operation management. That is, when the indicated value of the operating device reaches the target value, the polymerization reaction is stopped by returning the pressure of the reactor to normal pressure or by removing the polycarbonate resin from the reactor.

ADVANTAGE OF THE INVENTION According to this invention, the polycarbonate resin of the viscosity range which enables easy melt processing can be obtained in the temperature range which can suppress the thermal deterioration of polycarbonate resin, having sufficient mechanical properties. The preferable range of the viscosity which is the effect of the present invention is specifically that the melt viscosity is 2000 Pa · s or more and 6000 Pa · s or less under the measurement conditions of a temperature of 240 ° C. and a shear rate of 91.2 sec ⁻¹ . More preferably, it is 2300 Pa · s or more, and 2500 Pa · s or more is particularly preferable. On the other hand, the upper limit is more preferably 5300 Pa · s or less, and particularly preferably 5000 Pa · s or less. When the lower limit is not satisfied, the toughness of the polycarbonate resin is lowered, and film formation and stretching may be difficult. When the upper limit is not satisfied, the resin temperature becomes excessively high during melt processing, which may cause thermal degradation of the resin. The melt viscosity is measured using a capillary rheometer (manufactured by Toyo Seiki Seisakusho).

  According to the present invention, a polycarbonate resin having high heat resistance can be obtained. The high heat resistance which is the effect of the present invention is specifically obtained as having a high glass transition temperature of 133 ° C. or higher, more preferably 150 ° C. or higher, further preferably 155 ° C. or higher, particularly preferably 160 ° C. It is also possible to obtain a polycarbonate having the above glass transition point. This effect makes it possible to apply to applications that require durability and reliability at high temperatures and high humidity. Further, it is possible to obtain an effect that the polycarbonate resin can be obtained which is less likely to cause the polycarbonate resin to become brittle, to deteriorate the melt processability, to deteriorate the dimensional accuracy of the molded product, or to impair the transparency. May also be possible. In this respect, according to the present invention, it is also possible to obtain a polycarbonate having a glass transition temperature of 180 ° C. or lower, more preferably 175 ° C. or lower, more preferably 170 ° C. or lower.

  When a diester compound is used in the polycondensation reaction, if the by-product monohydroxy compound remains in the polycarbonate resin, it volatilizes during the melt processing and becomes an odor, which worsens the working environment, contaminates the molding machine, and molding. The appearance of the product may be damaged. When diphenyl carbonate (DPC), which is a particularly useful carbonic acid diester, is used, the by-product phenol has a relatively high boiling point and is not sufficiently removed even by a reaction under reduced pressure, and tends to remain in the polycarbonate resin.

According to the present invention, it may be possible to reduce the monohydroxy compound contained in the polycarbonate resin. The content of the monohydroxy compound is preferably 1000 ppm by weight or less. Further, it is preferably 700 ppm by weight or less, and particularly preferably 500 ppm by weight or less. In order to solve the above-mentioned problem, the monohydroxy compound is preferably as low as possible. However, it is difficult to eliminate the monohydroxy compound remaining in the polycarbonate resin by the melt polymerization method. Requires excessive effort. Usually, the above-mentioned problem can be sufficiently suppressed by reducing the content of the monohydroxy compound to 1 ppm by weight.

In order to reduce low molecular components such as monohydroxy compounds remaining in the polycarbonate resin, the polycarbonate resin is devolatilized with an extruder, the pressure at the end of the polymerization is 3 kPa or less, preferably 2 kPa or less, Preferably it is effective to make it 1 kPa or less.
When reducing the pressure at the end of the polymerization, if the reaction pressure is too low, the molecular weight may increase rapidly, making it difficult to control the reaction. It is preferable to produce by making the ester group terminal excessive and biasing the terminal group balance. The end group balance can be adjusted by the molar ratio of the total dihydroxy compound and the total diester compound.

  In addition to the monohydroxy compound, unreacted monomer components may become residual low molecular components in the polycarbonate resin. In particular, carbonic acid diester tends to remain. As with the remaining monohydroxy compound, these components can be reduced to a specific amount or less by controlling the end group balance and the reaction pressure at the end of the polymerization, or by devolatilizing the polycarbonate resin with an extruder. . In the polycarbonate resin of the present invention, the residual amount of carbonic acid diester is preferably 300 ppm by weight or less, more preferably 200 ppm by weight or less, and particularly preferably 150 ppm by weight or less. In order to solve the above problem, the content of the carbonic acid diester is preferably as low as possible. However, in the melt polymerization method, it is difficult to make the carbonic acid diester remaining in the polycarbonate resin zero. Excessive labor is required. Usually, the above problem can be sufficiently suppressed by reducing the content of carbonic acid diester to 1 ppm by weight.

  If the photoelastic coefficient of the polycarbonate resin is excessively large, when the retardation film is bonded to the polarizing plate, the image quality may be deteriorated such that the periphery of the screen is blurred in white. This problem is particularly noticeable when used in large display devices and flexible displays. The polycarbonate resin of the present invention is composed of the structural unit represented by the above formula (1) or (2) and an aliphatic structural unit, and reduces the content of other aromatic structures to the minimum necessary. It becomes possible to keep the elastic modulus low.

Specifically, for example, the photoelastic coefficient of the polycarbonate resin of the present invention can take a value of 19 × 10 ⁻¹² Pa ⁻¹ or less, and more preferably a value of 15 × 10 ⁻¹² Pa ⁻¹ or less. It is possible to take a value of 12 × 10 ⁻¹² Pa ⁻¹ or less.
According to the present invention, a polycarbonate resin having high intrinsic birefringence can be obtained. Polycarbonate resin having high intrinsic birefringence increases the birefringence developed by processing such as stretching, so the film thickness can be reduced to obtain the desired retardation, and the display thickness is reduced. Or the amount of material used can be reduced to reduce the cost. In view of this effect, it is possible to obtain a preferable polycarbonate resin having a birefringence (Δn) at a wavelength of 550 nm expressed under the stretching conditions described later of 0.0072 or more. It is also possible to obtain a polycarbonate resin that is more preferably 0.0075 or more, and still more preferably a polycarbonate resin that is 0.008 or more. .

[Additive]
In the polycarbonate resin of the present invention, a heat stabilizer, an antioxidant, a catalyst deactivator, an ultraviolet absorber, a light stabilizer, a release agent, a dye, and an impact improvement which are usually used within the range not impairing the object of the present invention. An agent, an antistatic agent, a lubricant, a lubricant, a plasticizer, a compatibilizing agent, a nucleating agent, a flame retardant, an inorganic filler, a foaming agent and the like may be included.

(Heat stabilizer)
If necessary, the polycarbonate resin of the present invention can be blended with a heat stabilizer in order to prevent a decrease in molecular weight and a deterioration in hue during melt processing. Examples of such heat stabilizers include conventionally known hindered phenol heat stabilizers and / or phosphorus heat stabilizers.

  As the hindered phenol compound, for example, the following compounds can be employed. 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2-tert-butyl-4-methoxyphenol, 2-tert-butyl-4,6-dimethylphenol, 2,6-di- tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,5-di-tert-butylhydroquinone, n-octadecyl-3- (3 ′, 5′-di- tert-butyl-4′-hydroxyphenyl) propionate, 2-tert-butyl-6- (3′-tert-butyl-5′-methyl-2′-hydroxybenzyl) -4-methylphenyl acrylate, 2,2 ′ -Methylene-bis- (4-methyl-6-tert-butylphenol), 2,2'-methylene-bis- (6-cyclohexyl) -4-methylphenol), 2,2'-ethylidene-bis- (2,4-di-tert-butylphenol), tetrakis- [methylene-3- (3 ', 5'-di-tert-butyl-4') -Hydroxyphenyl) propionate] -methane, 1,3,5-trimethyl-2,4,6-tris- (3,5-di-tert-butyl-4-hydroxybenzyl) benzene and the like. Among them, tetrakis- [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] -methane, n-octadecyl-3- (3 ′, 5′-di-tert- Butyl-4'-hydroxyphenyl) propionate, 1,3,5-trimethyl-2,4,6-tris- (3,5-di-tert-butyl-4-hydroxybenzyl) benzene is preferably used.

  As the phosphorus compound, for example, the following phosphorous acid, phosphoric acid, phosphonous acid, phosphonic acid, and esters thereof can be adopted, but phosphorus compounds other than these compounds can also be adopted. Is possible. Triphenyl phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, tridecyl phosphite, trioctyl phosphite, trioctadecyl phosphite, didecyl monophenyl phosphite , Dioctyl monophenyl phosphite, diisopropyl monophenyl phosphite, monobutyl diphenyl phosphite, monodecyl diphenyl phosphite, monooctyl diphenyl phosphite, bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol Diphosphite, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite, bis (nonylphenyl) pentaerythritol diphosphite, bis (2,4-di tert-butylphenyl) pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, tributyl phosphate, triethyl phosphate, trimethyl phosphate, triphenyl phosphate, diphenyl monoorxenyl phosphate, dibutyl phosphate, dioctyl phosphate, diisopropyl phosphate, 4, 4'-Biphenylenediphosphinic acid tetrakis (2,4-di-tert-butylphenyl), dimethyl benzenephosphonate, diethyl benzenephosphonate, dipropyl benzenephosphonate. These heat stabilizers may be used alone or in combination of two or more.

Such a heat stabilizer may be added to the reaction solution during melt polymerization, or may be added to the polycarbonate resin using an extruder and kneaded. When forming a film by the melt extrusion method, the heat stabilizer or the like may be added to an extruder to form a film, or the heat stabilizer or the like may be added to a polycarbonate resin using an extruder in advance. In addition, a pellet or the like may be used.
The blending amount of these heat stabilizers is preferably 0.0001 parts by weight or more, more preferably 0.0005 parts by weight or more, further preferably 0.001 parts by weight or more, when the polycarbonate resin is 100 parts by weight. 1 part by weight or less is preferable, 0.5 part by weight or less is more preferable, and 0.2 part by weight or less is more preferable.

(Catalyst deactivator)
By adding an acidic compound to the polycarbonate resin of the present invention to neutralize and deactivate the catalyst used in the polymerization reaction, the color tone and thermal stability can be improved. As an acidic compound used as a catalyst deactivator, a compound having a carboxylic acid group, a phosphoric acid group or a sulfonic acid group, or an ester thereof can be used, and in particular, the following formula (10) or (11) It is preferable to use a phosphorus compound containing a partial structure represented by

Examples of the phosphorus compound represented by the formula (10) or (11) include phosphoric acid, phosphorous acid, phosphonic acid, hypophosphorous acid, polyphosphoric acid, phosphonic acid ester, and acidic phosphoric acid ester. Among them, phosphorous acid, phosphonic acid, and phosphonic acid ester are more excellent in catalyst deactivation and coloring suppression effects, and phosphorous acid is particularly preferable.
Examples of phosphonic acid include phosphonic acid (phosphorous acid), methylphosphonic acid, ethylphosphonic acid, vinylphosphonic acid, decylphosphonic acid, phenylphosphonic acid, benzylphosphonic acid, aminomethylphosphonic acid, methylenediphosphonic acid, 1-hydroxyethane- Examples include 1,1-diphosphonic acid, 4-methoxyphenylphosphonic acid, nitrilotris (methylenephosphonic acid), and propylphosphonic anhydride.

  Examples of phosphonic acid esters include dimethyl phosphonate, diethyl phosphonate, bis (2-ethylhexyl) phosphonate, dilauryl phosphonate, dioleyl phosphonate, diphenyl phosphonate, dibenzyl phosphonate, dimethyl methylphosphonate, diphenyl methylphosphonate, and ethylphosphonic acid. Diethyl, diethyl benzylphosphonate, dimethyl phenylphosphonate, diethyl phenylphosphonate, dipropyl phenylphosphonate, diethyl (methoxymethyl) phosphonate, diethyl vinylphosphonate, diethyl hydroxymethylphosphonate, dimethyl (2-hydroxyethyl) phosphonate, p-methylbenzylphosphonate diethyl, diethylphosphonoacetic acid, diethylphosphonoacetic acid ethyl, diethylphosphonoacetic acid tert-butyl, (Robenzyl) diethyl phosphonate, diethyl cyanophosphonate, diethyl cyanomethylphosphonate, diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, diethylphosphonoacetaldehyde diethyl acetal, diethyl (methylthiomethyl) phosphonate Can be mentioned.

Acid phosphate esters include dimethyl phosphate, diethyl phosphate, divinyl phosphate, dipropyl phosphate, dibutyl phosphate, bis (butoxyethyl) phosphate, bis (2-ethylhexyl) phosphate, diisotridecyl phosphate, phosphate Examples include phosphoric acid diesters such as dioleyl, distearyl phosphate, diphenyl phosphate and dibenzyl phosphate, mixtures of diesters and monoesters, diethyl chlorophosphate, and zinc stearyl phosphate.

These may be used alone or in a combination of two or more in any combination and ratio.
If the amount of the phosphorus compound added to the polycarbonate resin is too small, the effect of catalyst deactivation and coloring suppression is insufficient, and if it is too much, the polycarbonate resin may be colored, especially under high temperature and high humidity. In the durability test, the polycarbonate resin is easily colored. The phosphorus compound is added in an amount corresponding to the amount of catalyst used in the polymerization reaction. The phosphorus compound is preferably 0.5 times mol or more and 5 times mol or less, and more preferably 0.7 times mol or more and 4 times mol or less with respect to 1 mol of the metal of the catalyst used in the polymerization reaction. Particularly preferred is 0.8 times mol or more and 3 times mol or less.

(Polymer alloy)
The polycarbonate resin of the present invention is an aromatic polycarbonate, aromatic polyester, aliphatic polyester, polyamide, polystyrene, polyolefin, acrylic, amorphous polyolefin, ABS, AS, for the purpose of modifying properties such as mechanical properties and solvent resistance. A polymer alloy may be obtained by kneading with one or more of synthetic resins such as polylactic acid and polybutylene succinate, rubber, and elastomer.

The above additives and modifiers are mixed with the polycarbonate resin of the present invention simultaneously or in any order by a mixer such as a tumbler, V-type blender, nauter mixer, Banbury mixer, kneading roll, or extruder. Of these, kneading with an extruder, particularly a twin screw extruder is preferred from the viewpoint of improving dispersibility.
[Method for producing retardation film]
(Method for producing unstretched film)
As a method of forming an unstretched film using the polycarbonate resin of the present invention, the polycarbonate resin is dissolved in a solvent and cast, and then the casting method for removing the solvent or the polycarbonate resin is melted without using the solvent. It is possible to adopt a melt film forming method in which the film is formed. Specific examples of the melt film forming method include a melt extrusion method using a T die, a calender molding method, a heat press method, a coextrusion method, a comelting method, a multilayer extrusion method, and an inflation molding method. The method for forming an unstretched film is not particularly limited. However, the casting method may cause a problem due to the residual solvent. Therefore, a T-die is preferably used because of the melt film-forming method, particularly ease of subsequent stretching treatment. The melt extrusion method used is preferred.

  When an unstretched film is formed by the melt film forming method, the forming temperature is preferably 280 ° C. or less, more preferably 270 ° C. or less, and particularly preferably 265 ° C. or less. When the molding temperature is too high, defects due to generation of foreign matters and bubbles in the obtained film may increase or the film may be colored. However, if the molding temperature is too low, the melt viscosity of the polycarbonate resin becomes too high, making it difficult to mold the original film, and it may be difficult to produce an unstretched film having a uniform thickness. Is usually 200 ° C. or higher, preferably 210 ° C. or higher, more preferably 220 ° C. or higher. Here, the molding temperature of the unstretched film is a temperature at the time of molding in the melt film forming method, and is usually a value obtained by measuring the polycarbonate resin temperature at the die outlet for extruding the molten polycarbonate resin.

Moreover, when a foreign material exists in a film, when it is used as a polarizing plate, it will be recognized as a defect such as light leakage. In order to remove foreign substances in the polycarbonate resin, a method of forming a film by attaching a polymer filter after the extruder and filtering the polycarbonate resin and then extruding it from a die is preferable. At that time, it is necessary to connect the extruder, polymer filter, and die with piping and transfer the molten polycarbonate resin. However, in order to suppress thermal deterioration in the piping as much as possible, each equipment is arranged so that the residence time is minimized. It is important to. Further, the steps of conveying and winding the film after extrusion are performed in a clean room, and the best care is required so that no foreign matter adheres to the film.

  The thickness of the unstretched film is determined according to the design of the film thickness of the retardation film after stretching and stretching conditions such as the stretching ratio. Is usually 30 μm or more, preferably 40 μm or more, more preferably 50 μm or more, and usually 200 μm or less, preferably 160 μm or less, more preferably 120 μm or less. In addition, if there is unevenness in the thickness of the unstretched film, it causes retardation in the retardation film. Therefore, the thickness of the portion used as the retardation film is preferably set thickness ± 3 μm or less, and set thickness ± 2 μm or less. It is more preferable that the thickness is set to be ± 1 μm or less.

  The length of the unstretched film in the longitudinal direction is preferably 500 m or more, more preferably 1000 m or more, and particularly preferably 1500 m or more. From the viewpoint of productivity and quality, when producing the retardation film of the present invention, it is preferable to continuously stretch, but usually it is necessary to adjust the conditions to match the predetermined retardation at the start of stretching. If the length of the film is too short, the amount of product that can be obtained after adjusting the conditions is reduced. In the present specification, the term “long” means that the dimension in the longitudinal direction is sufficiently larger than the width direction of the film, and is substantially capable of being coiled by being wound in the longitudinal direction. means. More specifically, it means that the dimension in the longitudinal direction of the film is 10 times or more larger than the dimension in the width direction.

  The unstretched film obtained as described above preferably has an internal haze of 3% or less, more preferably 2% or less, and particularly preferably 1% or less. If the internal haze of the unstretched film is larger than the upper limit, light scattering occurs, which may cause depolarization when laminated with a polarizer, for example. The lower limit value of the internal haze is not particularly defined, but is usually 0.1% or more. For the measurement of internal haze, the transparent film with adhesive that had been previously measured for haze was attached to both sides of the unstretched film, and the sample with the effect of external haze removed was used. The value obtained by subtracting the haze value from the measured value of the sample is defined as the internal haze value.

The b ^* value of the unstretched film is preferably 3 or less. If the b ^* value of the film is too large, problems such as coloring occur. The b ^* value is more preferably 2 or less, particularly preferably 1 or less. The b ^* value is measured using a spectrocolorimeter CM-2600d manufactured by Konica Minolta.
The unstretched film preferably has a total light transmittance of 80% or more, more preferably 85% or more, and particularly preferably 90% or more, regardless of the thickness. If the transmittance is not less than the above lower limit, a film with little coloring is obtained, and when it is bonded to a polarizing plate, it becomes a circularly polarizing plate with a high degree of polarization and transmittance, and when used in an image display device, a high display quality. Can be realized. The upper limit of the total light transmittance of the film of the present invention is not particularly limited, but is usually 99% or less.

(Method for producing retardation film)
A retardation film can be obtained by stretching and orienting the unstretched film. As the stretching method, a known method such as longitudinal uniaxial stretching, lateral uniaxial stretching using a tenter or the like, or simultaneous biaxial stretching and sequential biaxial stretching in combination thereof can be used. Stretching may be performed batchwise, but it is preferable in terms of productivity to be performed continuously. Further, a retardation film with less variation in retardation in the film surface can be obtained in the continuous method than in the batch method.

  The stretching temperature is in the range of (Tg-20 ° C) to (Tg + 30 ° C), preferably (Tg-10 ° C) to (Tg + 20 ° C) with respect to the glass transition temperature (Tg) of the polycarbonate resin used as a raw material. More preferably, it exists in the range of (Tg-5 degreeC)-(Tg + 15 degreeC). Although the draw ratio is determined by the target retardation value, it is 1.2 to 4 times, more preferably 1.5 to 3.5 times, and more preferably 2 to 3 times in the longitudinal and lateral directions. . When the draw ratio is too small, the effective range in which the desired degree of orientation and orientation angle can be obtained becomes narrow. On the other hand, if the stretch ratio is too large, the film may be broken or wrinkles may occur during stretching.

The stretching speed is also appropriately selected according to the purpose, but is usually 50 to 2000% / min, preferably 100 to 1500% / min, more preferably 200 to 1000% / min, especially at the strain rate represented by the following formula. Preferably, it can be selected to be 250 to 500% / min. If the stretching speed is excessively high, breakage during stretching may be caused, or fluctuations in optical characteristics due to long-term use under high temperature conditions may increase. Further, when the stretching speed is excessively low, not only the productivity is lowered, but also the stretching ratio may have to be excessively increased in order to obtain a desired phase difference.
Strain rate (% / min) = {stretching rate (mm / min) / length of original film (mm)} × 100

  After stretching the film, if necessary, a heat setting treatment may be performed by a heating furnace, or a relaxation treatment may be performed by controlling the width of the tenter or adjusting the roll peripheral speed. The temperature of the heat setting treatment is 60 ° C. to (Tg), preferably 70 ° C. to (Tg−5 ° C.) with respect to the glass transition temperature (Tg) of the polycarbonate resin used for the unstretched film. If the heat treatment temperature is too high, the orientation of the molecules obtained by stretching is disturbed, and there is a possibility that the desired retardation will be greatly reduced. Moreover, when providing a relaxation process, the stress which arose in the stretched film can be removed by shrink | contracting to 95%-99% with respect to the width | variety of the film expanded by extending | stretching. The treatment temperature applied to the film at this time is the same as the heat setting treatment temperature. By performing the heat setting process and the relaxation process as described above, it is possible to suppress fluctuations in optical characteristics due to long-term use under high temperature conditions.

The retardation film of the present invention can be produced by appropriately selecting and adjusting the processing conditions in such a stretching step.
In the retardation film of the present invention, the in-plane birefringence (Δn) at a wavelength of 550 nm is preferably 0.007 or more, more preferably 0.0075 or more, and particularly preferably 0.008 or more. Since the phase difference is proportional to the thickness (d) and birefringence (Δn) of the film, by making the birefringence within the specific range, it becomes possible to express a desired phase difference with a thin film thickness. It is possible to easily produce a film suitable for the above equipment. In order to develop high birefringence, it is necessary to increase the degree of orientation of the polymer molecules by lowering the stretching temperature, increasing the stretching ratio, etc., but the film easily breaks under such stretching conditions. The higher the toughness of the polycarbonate resin used, the more advantageous.

  The retardation film of the present invention preferably has a thickness of 50 μm or less, although it depends on the design value of the retardation. Further, the thickness of the retardation film is more preferably 40 μm or less, further preferably 35 μm or less, and particularly preferably 30 μm or less. On the other hand, if the thickness is excessively thin, handling of the film becomes difficult, wrinkles occur during production, or breakage occurs. Therefore, the lower limit of the thickness of the retardation film of the present invention is preferably 10 μm or more, More preferably, it is 15 μm or more.

The retardation film of the present invention has a retardation (R450) of wavelength 5 measured at a wavelength of 450 nm.
The value of chromatic dispersion (R450 / R550), which is the ratio to the phase difference (R550) measured at 50 nm, is 0.98 or more and 1.01 or less.
If the value of the chromatic dispersion is outside this range, the wavelength dependency of the hue becomes large, optical compensation is not performed at all wavelengths in the visible region, and coloring or contrast due to light passing through the polarizing plate or the display device. This causes problems such as lowering.

  The retardation film is laminated and bonded to a known polarizing film and cut into a desired dimension to form a circularly polarizing plate. Such circularly polarizing plates are used, for example, for viewing angle compensation of various displays (liquid crystal display devices, organic EL display devices, plasma display devices, FED field emission display devices, SED surface field display devices), antireflection of external light, color It can be used for compensation, conversion of linearly polarized light into circularly polarized light, and the like.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited by a following example, unless the summary is exceeded. Characteristic evaluation of the polycarbonate resin of the present invention and the retardation film was performed by the following method. The characteristic evaluation method is not limited to the following method and can be appropriately selected by those skilled in the art.

(1) Reduced viscosity A polycarbonate resin sample was dissolved in methylene chloride to prepare a polycarbonate resin solution having a concentration of 0.6 g / dL precisely. Measurement was performed at a temperature of 20.0 ° C. ± 0.1 ° C. using an Ubbelohde viscometer manufactured by Moriyu Rika Kogyo Co., Ltd., and a solvent passage time t ₀ and a solution passage time t were measured. The relative viscosity η _rel was obtained from the following equation (i) using the obtained values t ₀ and t, and the specific viscosity η _sp was obtained from the following equation (ii) using the obtained relative viscosity η _rel . .
η _rel = t / t ₀ (i)
η _sp = (η−η ₀ ) / η ₀ = η _rel −1 (ii)
Thereafter, the reduced viscosity η _sp / c [dL / g] was determined by dividing the obtained specific viscosity η _sp by the concentration c [g / dL].

(2) Melt viscosity A pellet-like polycarbonate resin sample was vacuum-dried at 90 ° C for 5 hours or more. Measurement was performed using a capillary rheometer manufactured by Toyo Seiki Seisakusho, using the dried pellets. Measurement temperature was 240 ° C., measured melt viscosity between shear rate 9.12~1824sec ^-1, using a value of melt viscosity at 91.2sec ^-1. An orifice having a die diameter of φ1 mm × 10 mmL was used. In the following examples and comparative examples, those having a melt viscosity of 2000 Pa · s or more and 5300 Pa · s or less were evaluated as having excellent moldability and having a viscosity suitable for melt moldability.

(3) Glass transition temperature (Tg)
This was measured using a differential scanning calorimeter DSC 6220 manufactured by SII Nano Technology. About 10 mg of a polycarbonate resin sample was put in an aluminum pan made by the same company, sealed, and heated from 30 ° C. to 250 ° C. at a temperature rising rate of 20 ° C./min in a nitrogen stream of 50 mL / min. After maintaining the temperature for 3 minutes, it was cooled to 30 ° C. at a rate of 20 ° C./min. The temperature was maintained at 30 ° C. for 3 minutes, and the temperature was increased again to 200 ° C. at a rate of 20 ° C./min. From the DSC data obtained at the second temperature increase, a straight line obtained by extending the base line on the low temperature side to the high temperature side, and a tangent line drawn at a point where the slope of the step change portion of the glass transition becomes maximum The extrapolated glass transition start temperature, which is the temperature of the intersection point, was determined and used as the glass transition temperature. In the following examples and comparative examples, those having a glass transition point of 133 ° C. or higher were evaluated as having excellent heat resistance.

(4) Measurement of content of monohydroxy compound and carbonic acid diester in polycarbonate resin Weigh accurately about 1 g of polycarbonate resin sample, dissolve in 5 mL of methylene chloride to make a solution, then add acetone so that the total amount is 25 mL Then, reprecipitation treatment was performed. Next, the treatment liquid was measured by liquid chromatography.

The equipment and conditions used are as follows.
・ Device: manufactured by Shimadzu Corporation System controller: CBM-20A
Pump: LC-10AD
Column oven: CTO-10ASvp
Detector: SPD-M20A
Analysis column: Cadenza CD-18 4.6 mmφ × 250 mm
Oven temperature: 60 ° C
・ Detection wavelength: 220 nm
Eluent: A solution: 0.1% phosphoric acid aqueous solution, B solution: acetonitrile A / B = 50/50 (vol%) to A / B = 0/100 (vol%) gradient in 10 minutes, A / Hold for 5 minutes at B = 0/100 (vol%) Flow rate: 1 mL / min
Sample injection volume: 10 μL
For each compound, the content of each compound in the polycarbonate resin is prepared by changing the concentration of each compound, measuring under the same conditions as the above liquid chromatography, creating a calibration curve, and calculating by the absolute calibration curve method. did.

(5) Molding of film Using polycarbonate resin pellets vacuum-dried at 90 ° C. for 5 hours or longer, using a single screw extruder (screw diameter 25 mm, cylinder set temperature: 220 ° C. to 270 ° C.) manufactured by Isuzu Chemical Industries, Ltd. And extruded from a T die (width 200 mm, set temperature: 200 to 270 ° C.). The extruded film was rolled by a winder while being cooled by a chill roll (set temperature: 120 to 170 ° C.) to prepare an unstretched film.

(6) Measurement of refractive index and Abbe number A rectangular test piece having a length of 40 mm and a width of 8 mm was cut out from an unstretched film to obtain a measurement sample. Refractive index n _C of each wavelength by multi-wavelength Abbe refractometer DR-M4 / 1550 manufactured by Atago Co., Ltd. using interference filters with wavelengths of 656 nm (C line), 589 nm (D line), and 486 nm (F line) n _D and n _F were measured. The measurement was performed at 20 ° C. using monobromonaphthalene as the interfacial liquid. The Abbe number ν _d was calculated by the following equation.
ν _d = (1−n _D ) / (n _C −n _F )
The larger the Abbe number, the smaller the wavelength dependency of the refractive index.

(7) Measurement of total light transmittance An unstretched film having a film thickness of about 100 μm was prepared by the melt extrusion method described above, and the total light transmittance was measured using a turbidimeter COH400 manufactured by Nippon Denshoku Industries Co., Ltd. .

(8) Measurement of photoelastic coefficient A device combining a birefringence measuring device comprising a He-Ne laser, a polarizer, a compensation plate, an analyzer and a photodetector and a vibration type viscoelasticity measuring device (DVE-3 manufactured by Rheology). It measured using. (For details, see Journal of Japanese Society of Rheology, Vol. 19, p93-97 (1991).)
A test piece having a length of 20 mm and a width of 5 mm was cut out from the unstretched film, fixed to a viscoelasticity measuring apparatus, and the storage elastic modulus E ′ was measured at a room temperature of 25 ° C. at a frequency of 96 Hz. At the same time, the emitted laser light is passed through the polarizer, sample, compensator, and analyzer in this order, picked up by a photodetector (photodiode), and passed through a lock-in amplifier with respect to the amplitude and distortion of the waveform of angular frequency ω or 2ω. The phase difference was determined, and the strain optical coefficient O ′ was determined. At this time, the directions of the polarizer and the analyzer were orthogonal to each other, and each was adjusted so as to form an angle of π / 4 with respect to the extending direction of the sample. The photoelastic coefficient C was obtained from the following equation using the storage elastic modulus E ′ and the strain optical coefficient O ′.
C = O '/ E'
In the following examples and comparative examples, those having a photoelastic coefficient of 19 × 10 ⁻¹² Pa ⁻¹ or less were evaluated as excellent in that the change in optical physical properties due to the expansion and contraction of the film due to the change in use environment was small. did.

(9) Measurement of birefringence (Δn) and wavelength dispersion (R450 / R550) A test piece having a length of 125 mm and a width of 50 mm was cut out from the unstretched film. Using a batch type biaxial stretching apparatus (Biaxial stretching apparatus BIX-277-AL manufactured by Island Kogyo Co., Ltd.), free end uniaxial stretching of the test piece was performed at a stretching speed of 300% / min and a stretching ratio of 2 times. A retardation film was obtained. The stretching temperature was the glass transition temperature of the polycarbonate resin + 10 ° C., and the temperature was lowered by 1 ° C. until the film was broken. The center part of the stretched film obtained under the temperature condition just before the breakage is cut into a length of 4 cm and a width of 4 cm, and a measurement wavelength of 450, 500 is measured using a phase difference measuring device KOBRA-WPR manufactured by Oji Scientific Instruments. The phase difference was measured at 550, 590, and 630 nm, and the wavelength dispersion was measured. The wavelength dispersion was shown by the ratio of the phase differences R450 and R550 measured at 450 nm and 550 nm (R450 / R550) and the ratio of the phase differences R630 and R550 measured at 630 nm and 550 nm (R630 / R550).

Moreover, birefringence (DELTA) n was calculated | required from following Formula from phase difference R550 of 550 nm and the film thickness of a stretched film.
Birefringence Δn = R550 [nm] / (film thickness [mm] × 10 ⁶ )
In the following Examples and Comparative Examples, those having a birefringence Δn of 0.072 or more were evaluated as being excellent because it was possible to realize a thin film.
The present invention provides a polycarbonate resin that is designed to balance various physical properties, a transparent film formed by molding the polycarbonate resin, and a stretched retardation film. Both are excellent at the same time.

(Example of monomer synthesis)
[Synthesis Example 1] Synthesis of bis [9- (2-phenoxycarbonylethyl) fluoren-9-yl] methane (the following formula (12)) [Synthesis Example 2] 1,2-bis [9- (3-hydroxypropyl) ) -Fluoren-9-yl] methane (Formula (13)) Synthesis Example 3 Synthesis of bis (9-hydroxymethylfluoren-9-yl) methane (Formula (14)) Synthesis Example 1 -The compound of the synthesis example 3 was synthesize | combined according to the method of Unexamined-Japanese-Patent No. 2015-25111.

Synthesis Example 4 Synthesis of 6,6′-dihydroxy-3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane (the following formula (15))
The compound of Synthesis Example 4 was synthesized according to the method described in JP 2014-114281 A.

[Synthesis Example 5] DL-2,3: 5,6-di-O-cyclohexylidene-myo-inositol (the following formula (16))
A 500 mL reaction vessel equipped with a Dimroth was purged with nitrogen, and then 30 mg (167 mmol) of myo-inositol, 200 mL of DMF, 863 mg of p-toluenesulfonic acid monohydrate, and 75 mL of dimethoxycyclohexane were added and stirred at 100 ° C. for 3 hours. After cooling to 40 ° C., 2.5 mL of triethylamine was added, and DMF as a reaction solvent was distilled off under reduced pressure. Thereafter, 250 mL of ethyl acetate was added, and liquid separation was performed with 300 mL of a 5% aqueous sodium carbonate solution, followed by washing once with 300 mL of ion-exchanged water. The solvent was distilled off from the obtained organic phase under reduced pressure, crystallization was performed with 50 mL of ethyl acetate / 70 mL of n-hexane, and the resulting white precipitate was filtered. Thereafter, crystallization was performed again with 50 mL of ethyl acetate / 70 mL of n-hexane. The obtained solid was vacuum-dried at 60 ° C. for 5 hours to obtain 9.8 g of the target compound (yield 17
. 2%).

[Synthesis example and characteristic evaluation of polycarbonate resin]
Abbreviations and the like of compounds used in the following examples and comparative examples are as follows.
BF1: bis [9- (2-phenoxycarbonylethyl) fluoren-9-yl] methane BF2: 1,2-bis [9- (3-hydroxypropyl) -fluoren-9-yl] methane BF3: bis (9-hydroxymethylfluoren-9-yl) methane SBI: 6,6′-dihydroxy-3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane DCMI: DL-2,3: 5,6-Di-O-cyclohexylidene-myo-inositol. ISB: Isosorbide (trade name: POLYSORB, manufactured by Rocket Fleure)
CHDM: 1,4-cyclohexanedimethanol (cis, trans mixture, manufactured by SK Chemical Company)
-TCDDM: Tricyclodecane dimethanol (Oxea)
・ SPG: Spiroglycol (Mitsubishi Gas Chemical Co., Ltd.)
BPA: 2,2-bis (4-hydroxyphenyl) propane (manufactured by Mitsubishi Chemical Corporation)
BHEPF: 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene (manufactured by Osaka Gas Chemical Co., Ltd.)
BCF: 9,9-bis (4-hydroxy-3-methylphenyl) fluorene (manufactured by Osaka Gas Chemical Co., Ltd.)
・ DPC: Diphenyl carbonate (Mitsubishi Chemical Corporation)

[Example 1]
ISB 54.24 parts by weight (0.371 mol), TCDDM 25.26 parts by weight (0.059 mol), BF1 11.28 parts by weight (0.0018 mol), DPC 103.30 parts by weight (0.482 mol), and catalyst Calcium acetate monohydrate 8.81 × 10 ⁻⁴ parts by weight (5.00 × 10 ⁻⁶ mol) was charged into the reaction vessel, and the inside of the reaction apparatus was purged with nitrogen under reduced pressure. In a nitrogen atmosphere, the raw materials were dissolved while stirring at 150 ° C. for about 10 minutes. As the first step of the reaction, the temperature was raised to 220 ° C. over 30 minutes, and the reaction was performed at normal pressure for 60 minutes. Next, the pressure was reduced from normal pressure to 13.3 kPa over 90 minutes, maintained at 13.3 kPa for 30 minutes, and the generated phenol was extracted out of the reaction system. Next, as the second step of the reaction, the temperature of the heating medium was raised to 240 ° C. over 15 minutes, the pressure was reduced to 0.10 kPa or less over 15 minutes, and the generated phenol was extracted out of the reaction system. After reaching a predetermined stirring torque, the reaction was stopped by returning the pressure to normal pressure with nitrogen, the produced polyester carbonate was extruded into water, and the strand was cut to obtain pellets. Various evaluations described above were performed using the obtained polyester carbonate pellets. The evaluation results are shown in Table 1.
Since Example 1 has a preferable glass transition temperature and melt viscosity, it is excellent in heat resistance, melt processability, and mechanical properties. Further, since the residual amount of phenol is low, it is possible to prevent the molding machine from being contaminated during molding and appearance defects of the molded product, and the productivity is excellent. It also has high orientation (Δn), low photoelastic coefficient, high refractive index and excellent optical properties.

[Example 2]
ISB 50.70 parts by weight (0.347 mol), SPG 30.20 parts by weight (0.099 mol), BF1 11.28 parts by weight (0.018 mol), DPC 91.80 parts by weight (0.429 mol), and catalyst Polyester carbonate pellets were obtained in the same manner as in Example 1 except that 7.86 × 10 ⁻⁴ parts by weight (4.46 × 10 ⁻⁶ mol) of calcium acetate monohydrate was used. Various evaluations described above were performed using the obtained polyester carbonate pellets. The evaluation results are shown in Table 1.
Example 2 has excellent heat resistance, melt processability, mechanical properties, and optical properties as in Example 1. In particular, since it has a low photoelastic coefficient and excellent optical properties, it is excellent in that it has an appropriate glass transition temperature and melt viscosity, so it is suitable for use in a high temperature and high humidity environment.

[Example 3]
ISB 52.62 parts by weight (0.360 mol), CHDM 20.28 parts by weight (0.141 mol), BF1 21.14 parts by weight (0.033 mol), DPC 100.20 parts by weight (0.468 mol), and catalyst Polyester carbonate pellets were obtained in the same manner as in Example 1 except that 8.82 × 10 ⁻⁴ parts by weight (5.01 × 10 ⁻⁶ mol) of calcium acetate monohydrate was used. Various evaluations described above were performed using the obtained polyester carbonate pellets. The evaluation results are shown in Table 1.
Example 3 has excellent heat resistance, melt processability, mechanical properties, and optical properties as in Example 1. In particular, since it has a high birefringence compared to Example 1, the film thickness necessary for expressing a desired phase difference can be reduced when it is formed into a film, so it is more suitable for members that require a thin film. ing.

[Example 4]
ISB 74.54 parts by weight (0.510 mol), BF1 18.33 parts by weight (0.029 mol), DPC 103.14 parts by weight (0.481 mol), and calcium acetate monohydrate 8.99 × 10 6 as the catalyst ^-4 parts by weight (5.10 × 10 ⁻⁶ mol) was used in the same manner as in Example 1, except that the stop stirring torque was higher than in Example 1 and the polymerization was allowed to proceed to a higher melt viscosity. Polyester carbonate pellets were obtained. Various evaluations described above were performed using the obtained polyester carbonate pellets. The evaluation results are shown in Table 1.
Example 4 has excellent heat resistance, melt processability, mechanical properties, and optical properties as in Example 1. In particular, among the examples, an excellent glass transition temperature can be realized, so that the balance between heat resistance and melt processability is extremely excellent, and it is particularly suitable for use in a high temperature and high humidity environment.

[Example 5]
ISB 68.72 parts by weight (0.470 mol), SBI 8.05 parts by weight (0.026 mol), BF1 15.51 parts by weight (0.024 mol), DPC 101.15 parts by weight (0.472 mol), and catalyst In the same manner as in Example 1, except that 8.74 × 10 ⁻⁴ parts by weight (4.96 × 10 ⁻⁶ mol) of calcium acetate monohydrate was used and the stop stirring torque was higher than that in Example 1. Polyester carbonate pellets were obtained. Various evaluations described above were performed using the obtained polyester carbonate pellets. The evaluation results are shown in Table 1.
Example 5 has excellent heat resistance, melt processability, mechanical properties, and optical properties as in Example 1. In particular, since it has a high glass transition temperature among the examples, it is extremely excellent in heat resistance. In addition, since the residual amount of phenol is extremely small, it is possible to prevent contamination of the molding machine and defective appearance of the molded product during molding.

[Example 6]
ISB 68.78 parts by weight (0.471 mol), DCMI 8.05 parts by weight (0.024 mol), BF1 15.51 parts by weight (0.024 mol), DPC 100.70 parts by weight (0.470 mol), and catalyst In the same manner as in Example 1, except that 1.74 × 10 ⁻³ parts by weight (9.89 × 10 ⁻⁶ mol) of calcium acetate monohydrate was used and the stop stirring torque was higher than that in Example 1. Polyester carbonate pellets were obtained. Various evaluations described above were performed using the obtained polyester carbonate pellets. The evaluation results are shown in Table 1.
Example 6 has excellent heat resistance, melt processability, mechanical properties, and optical properties as in Example 1. In particular, among the examples, since it has a high glass transition temperature and a low photoelastic coefficient, it is extremely excellent in heat resistance and optical characteristics.

[Comparative Example 1]
ISB 59.63 parts by weight (0.408 mol), CHDM 25.22 parts by weight (0.175 mol), DPC 126.12 parts by weight (0.589 mol), and calcium acetate monohydrate 1.54 × 10 6 as a catalyst Polycarbonate resin pellets were obtained in the same manner as in Example 1 except that ⁻⁴ parts by weight (8.74 × 10 ⁻⁷ mol) was used and the final polymerization temperature was 220 ° C. Using the obtained polycarbonate resin pellets, the various evaluations described above were performed. The evaluation results are shown in Table 1.
Since Comparative Example 1 has a low glass transition temperature compared to the Examples, it is not only inferior in heat resistance, but also has a low melt viscosity. For example, it is not suitable for molding in a process that requires a high temperature. It is inferior in heat workability.

[Comparative Example 2]
ISB 54.65 parts by weight (0.374 mol), TCDDM 31.46 parts by weight (0.160 mol), DPC 115.59 parts by weight (0.540 mol), and calcium acetate monohydrate as the catalyst 1.41 × 10 Polycarbonate resin pellets were obtained in the same manner as in Example 1 except that ⁻⁴ parts by weight (8.01 × 10 ⁻⁷ mol) was used and the final polymerization temperature was 220 ° C. Using the obtained polycarbonate resin pellets, the various evaluations described above were performed. The evaluation results are shown in Table 1.
Comparative Example 2 is similar to Comparative Example 1 because it has a lower glass transition temperature than the Example, so it is not only inferior in heat resistance, but also has a low melt viscosity. For example, it is suitable for molding in processes that require high temperatures. It is inferior in workability in that it is not.

[Comparative Example 3]
ISB 40.22 parts by weight (0.275 mol), CHDM 13.54 parts by weight (0.094 mol), BHEPF 34.60 parts by weight (0.079 mol), DPC 96.93 parts by weight (0.452 mol), and catalyst In the same manner as in Example 1 except that 7.89 × 10 ⁻⁴ parts by weight (4.48 × 10 ⁻⁶ mol) of calcium acetate monohydrate was used, pellets of polycarbonate resin were obtained. Using the obtained polycarbonate resin pellets, the various evaluations described above were performed. The evaluation results are shown in Table 1.

[Comparative Example 4]
ISB 29.85 parts by weight (0.204 mol), CHDM 27.88 parts by weight (0.193 mol), BCF 29.89 parts by weight (0.079 mol), DPC 104.12 parts by weight (0.486 mol), and catalyst In the same manner as in Example 1, except that 4.20 × 10 ⁻³ parts by weight (2.38 × 10 ⁻⁵ mol) of calcium acetate monohydrate was used, polycarbonate resin pellets were obtained. Using the obtained polycarbonate resin pellets, the various evaluations described above were performed. The evaluation results are shown in Table 1.

[Comparative Example 5]
ISB 55.18 parts by weight (0.378 mol), BHEPF 33.04 parts by weight (0.075 mol), DPC 98.00 parts by weight (0.457 mol), and calcium acetate monohydrate 7.98 × 10 6 as a catalyst Polycarbonate resin pellets were obtained in the same manner as in Example 1 except that ^-4 parts by weight (4.53 × 10 ⁻⁶ mol) was used. Using the obtained polycarbonate resin pellets, the various evaluations described above were performed. The evaluation results are shown in Table 1.

  Comparative Examples 3 to 5 are results of using a polycarbonate containing a structural unit derived from a monomer having a fluorene moiety in the side chain, similarly to the oligofluorene structural unit used in the present invention. The wavelength dispersions of Comparative Examples 3 to 5 all exhibited flat dispersibility. However, in comparison with Examples, in Comparative Examples 3 to 5, the content of the structural unit derived from the fluorene-containing monomer in the polycarbonate resin must be increased in order to flatten the wavelength dispersion, and as a result, the polycarbonate The ratio of the aromatic structural unit in the resin is increased, and the orientation Δn and the photoelastic coefficient under the limit stretching conditions of Comparative Examples 3 to 5 are inferior to the results of Examples, and the optical properties are not excellent. This result is considered to result from the difference in performance of the fluorene-containing monomer, and it can be seen that the reverse wavelength dispersibility can be expressed with high efficiency even with a small amount of the oligofluorene structural unit used in the present invention.

[Comparative Example 6]
Various evaluations described above were performed using ZEONOR 1420R (cycloolefin polymer) manufactured by Nippon Zeon Co., Ltd. The evaluation results are shown in Table 1.
The comparative example 6 is inferior to the orientation compared with an Example. Therefore, in order to express a desired phase difference when it is used as a film, the film thickness must be increased, which is not suitable for a member that requires thinning.

[Comparative Example 7]
The various evaluations described above were performed using Novalex 7022R (BPA polycarbonate) manufactured by Mitsubishi Engineering Plastics. The evaluation results are shown in Table 1.
Since Comparative Example 7 has a high melt viscosity, it is not suitable for molding in a process that requires a high temperature. Further, since the photoelastic coefficient is extremely large, the optical characteristics are not excellent.

[Comparative Example 8]
According to Experimental Example 1 of JP2015-25111, a polycarbonate resin was synthesized and subjected to the various evaluations described above. The evaluation results are shown in Table 1.

[Comparative Example 9]
According to Experimental Example 4 of JP2015-25111, a polycarbonate resin was synthesized and subjected to the various evaluations described above. The evaluation results are shown in Table 1.

Comparative Examples 8 and 9 are polycarbonate resins containing the same oligofluorene structural unit as in Examples 1-6. However, in Comparative Example 8, the content of the oligofluorene structural unit for expressing the desired wavelength dispersion is increased, and the orientation Δn is inferior. Therefore, in order to express a desired phase difference when it is used as a film, the film thickness must be increased, which is not suitable for a member that requires thinning. Further, Comparative Example 9 has a large photoelastic coefficient and is not excellent in optical characteristics. Moreover, since there is also a large amount of residual phenol, it causes contamination of the molding machine and defective appearance of the molded product in the molding process. In Comparative Example 9, the wavelength dispersion is unexpectedly increased in the positive direction. This is presumed that the distance between the carbonyl group and the fluorene ring in the oligofluorene structural unit is too close, and the fluorene ring cannot be oriented in a preferred direction due to the steric hindrance of the carbonyl group. As described above, the molecular design of the oligofluorene structural unit is important in order to develop ideal optical properties.

Claims (7)

When the total amount of all the structural units and the linking group comprising the structural unit represented by the following formula (1) or (2) is 100% by weight, the following formula (1) or ( 2) A polycarbonate resin containing 1 wt% or more and 18 wt% or less of the structural unit represented by
The ratio of the retardation (R450) at a wavelength of 450 nm to the retardation (R550) at a wavelength of 550 nm (R450 / R550) of the stretched film made from the polycarbonate resin is 0.98 or more and 1.01 or less. Oh it is,
A polycarbonate resin containing 50% by weight or more of the structural unit represented by the following formula (3) when the total amount of all the structural units constituting the polycarbonate resin and the weight of the linking group is 100% by weight .
(In Formula (1) and (2), R < ¹ > -R < ³ > is a C1-C4 alkylene group which may have a direct bond and a substituent each independently, R < ⁴ > -R < ⁹ >. Each independently has a hydrogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, an optionally substituted aryl group having 4 to 10 carbon atoms, and a substituent. An optionally substituted acyl group having 1 to 10 carbon atoms, 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 optionally substituted acyloxy group having 1 to 10 carbon atoms, an amino group optionally having substituents, a vinyl group having 1 to 10 carbon atoms optionally having substituents, and a substituent An ethynyl group having 1 to 10 carbon atoms, a sulfur atom having a substituent, and a silicon having a substituent. Atom, a halogen atom, a nitro group, or a cyano group. However, they may form a ring adjacent the at least two groups are bonded to each other among the R ⁴ to R ^9.) All structural units constituting the polycarbonate resin, and the total amount of the weight of the linking group upon 100% by weight, the formula (3) represented by the structural units 50% by weight or more, containing 75 wt% or less The polycarbonate resin according to claim 1.   When the total amount of all the structural units constituting the polycarbonate resin and the linking group is 100% by weight, an aliphatic dihydroxy compound, an alicyclic dihydroxy compound, a dihydroxy compound containing an acetal ring, an oxyalkylene glycol, The polycarbonate resin according to claim 1 or 2, comprising a structural unit derived from at least one compound selected from aromatic dihydroxy compounds in an amount of 0.1 wt% to 60 wt%.   The structural unit derived from an aromatic compound is contained in an amount of not more than 25% by weight when the total amount of all the structural units constituting the polycarbonate resin and the weight of the linking group is 100% by weight. The polycarbonate resin according to item 1.   The transparent film formed by shape | molding the polycarbonate resin of any one of Claims 1 thru | or 4.   The transparent film according to claim 5, which is formed by a melt film forming method at a forming temperature of 280 ° C. or less.   A retardation film formed by stretching the film according to claim 5 or 6 in at least one direction.