JP2016069466A - Optical film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical film having high heat resistance, low phase difference and good fluidity.SOLUTION: There are provided: a polycarbonate resin obtained, for example, by heating 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 9-bis[4-(2-hydroxyethoxy)phenyl]fluorene, 2,2-bis(4-hydroxyphenyl)propane, diphenyl carbonate, and tetramethyl ammonium hydroxide and sodium hydrogen carbonate as a catalyst in a nitrogen atmosphere; and an optical film using the resin.SELECTED DRAWING: None

Description

  The present invention relates to an optical film having high heat resistance, low retardation, and good fluidity.

  Conventionally, a polycarbonate resin (hereinafter referred to as PC-A) obtained by reacting a carbonate precursor with 2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as bisphenol A) has transparency, heat resistance, mechanical properties. It has been widely used in many fields as an engineering plastic because of its excellent characteristics and dimensional stability. Furthermore, in recent years, utilization of the transparency as an optical material in the fields of optical disks, films, lenses and the like has been developed.

However, when using the film which consists of PC-A for the board | substrate for transparent conductive films, heat resistance was not enough and it was difficult to use it.
Therefore, various methods have been studied as countermeasures against the above problems. As one of them, it is proposed that a polycarbonate resin having high heat resistance can be obtained by reacting a carbonate precursor with bisphenol A and 9,9-bis (4-hydroxy-3-methylphenyl) fluorene (for example, Patent Document 1). 2), it is proposed to use a film made of the polycarbonate resin for a retardation film and a protective film for a polarizing plate (see, for example, Patent Documents 3, 4, 5, and 6). However, the polycarbonate resin has a high melt viscosity and is limited to film formation by the solution casting method.

  In addition, it has been proposed to form a polycarbonate resin composed of 9,9-bis (4-hydroxy-3-methylphenyl) fluorene and spiroglycol by a melt film forming method (Patent Document 7). However, a resin having a glass transition temperature of 150 ° C. or higher has a low thermal decomposition temperature, so that melt film formation is difficult, and decomposition occurs during film formation, causing bubbles and gels. Moreover, the strength of the film was low, and there was a problem in the bending characteristics.

  In addition, a sheet in which a polycarbonate resin obtained by copolymerizing 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, bisphenol A, and a siloxane compound is formed into a melt has been proposed (Patent Document 8). However, since the ratio of 9,9-bis (4-hydroxy-3-methylphenyl) fluorene is high, the film is brittle and there is no description regarding optical properties. Further, a polarizing plate protective film containing 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene has been proposed, but the heat resistance is not sufficient (Patent Document 9).

JP 2004-331688 A JP-A-8-134199 International Publication No. 2000/026705 Pamphlet International Publication 2001/009649 Pamphlet JP 2001-296423 A JP 2001-194530 A Japanese Patent No. 5119250 JP 2011-89050 A JP 2012-103507 A

  An object of the present invention is to provide an optical film having high heat resistance, low retardation, and good fluidity.

As a result of intensive studies, the present inventors have found that it is important to react a carbonate precursor with a specific composition ratio between a bisphenol compound having two fluorene structures and an aromatic dihydroxy compound. This phenomenon differs from the conventional phenomenon of birefringence in stretching, and surprisingly, it was found that the phase difference can be reduced only with a composition in a very narrow region, and has high heat resistance, low phase difference, and fluidity. It was found that an optical film having a good thickness can be obtained.
That is, the present invention is as follows.

［式（Ａ）中、Ｒ_１およびＲ_２は夫々独立して、水素原子、炭素原子数１〜１０の芳香族基を含んでもよい炭化水素基またはハロゲン原子を示し、ｍおよびｎは夫々独立して０〜４の整数を示す。］
で表される単位（Ａ）と下記式

［式（Ｂ）中、Ｒ_３、Ｒ_４は夫々独立して水素原子、炭素原子数１〜９の芳香族基を含んでもよい炭化水素基またはハロゲン原子であり、ｐおよびｑは夫々独立して０〜４の整数を示す。Ｗは、単結合または下記式（Ｗ）

であり、ここにＲ_５とＲ_６はそれぞれ、水素原子、フッ素原子、塩素原子、臭素原子、ヨウ素原子、炭素原子数１〜９のアルキル基、炭素原子数１〜５のアルコキシ基、炭素原子数６〜１２のアリール基、炭素原子数２〜５のアルケニル基、または炭素原子数７〜１７のアラルキル基を表す。また、Ｒ_５とＲ_６が結合して炭素環または複素環を形成しても良い。Ｒ_７とＲ_８はそれぞれ、水素原子、フッ素原子、塩素原子、臭素原子、ヨウ素原子、炭素原子数１〜９のアルキル基、炭素原子数１〜５のアルコキシ基、または炭素原子数６〜１２アリール基を表す。Ｒ_９は１〜９のアルキレン基である。ａは１〜２０の整数を表し、ｂは１〜５００の整数を表す。］
で表される単位（Ｂ）と下記式

［式中、Ｒ_１０およびＲ_１１は夫々独立して、水素原子、炭素原子数１〜１０の芳香族基を含んでもよい炭化水素基またはハロゲン原子を示し、Ｒ_１２およびＲ_１３は夫々独立して、炭素原子数１〜１０の芳香族基を含んでもよい炭化水素基を示し、ｓおよびｔは夫々独立して０〜４の整数を示し、ｒおよびｋは、夫々独立して１以上の整数を示す。］
で表される単位（Ｃ）を含むポリカーボネート樹脂であって、単位（Ａ）と単位（Ｂ）と単位（Ｃ）とのモル比（Ａ／Ｂ／Ｃ）が、単位（Ａ）、単位（Ｂ）および単位（Ｃ）の合計を１００モル％として、Ａ／Ｂ／Ｃ＝３〜９０モル％／３〜９０モル％／３〜９０モル％の範囲であり、２０℃の塩化メチレン溶液で測定された比粘度が０．１８〜０．３４であるポリカーボネート樹脂を溶融押出して得られる光学フィルム。
２．ポリカーボネート樹脂のガラス転移温度が１５０〜１９０℃である前項１記載の光学フィルム。
３．波長５５０ｎｍにおける面内位相差値Ｒｅの絶対値が２０ｎｍ以下であり、厚み方向位相差値Ｒｔｈの絶対値が５０ｎｍ以下である前項１記載の光学フィルム。
４．ゲル数が１００個／ｍ^２以下である前項１記載の光学フィルム。
５．前項１記載の光学フィルムを用いたタッチパネル用基板。 1. The main repeating unit is the following formula

[In Formula (A), R ₁ and R ₂ each independently represent a hydrogen atom, a hydrocarbon group that may contain an aromatic group having 1 to 10 carbon atoms, or a halogen atom, and m and n each independently And represents an integer of 0 to 4. ]
Unit (A) represented by the following formula

[In the formula (B), R ₃ and R ₄ are each independently a hydrogen atom, a hydrocarbon group which may contain an aromatic group having 1 to 9 carbon atoms or a halogen atom, and p and q are each independently Represents an integer of 0 to 4. W is a single bond or the following formula (W)

Where R ₅ and R ₆ are a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group having 1 to 9 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and a carbon atom, respectively. It represents an aryl group having 6 to 12 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an aralkyl group having 7 to 17 carbon atoms. R ₅ and R ₆ may combine to form a carbocyclic or heterocyclic ring. R ₇ and R ₈ are each a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group having 1 to 9 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or 6 to 12 carbon atoms. Represents an aryl group. R ₉ is an alkylene group of 1 to 9. a represents an integer of 1 to 20, and b represents an integer of 1 to 500. ]
Unit (B) represented by the following formula

[Wherein, R ₁₀ and R ₁₁ each independently represent a hydrogen atom, a hydrocarbon group which may contain an aromatic group having 1 to 10 carbon atoms, or a halogen atom, and R ₁₂ and R ₁₃ each independently represent A hydrocarbon group which may contain an aromatic group having 1 to 10 carbon atoms, s and t each independently represent an integer of 0 to 4, and r and k each independently represents 1 or more. Indicates an integer. ]
A polycarbonate resin containing a unit (C) represented by the formula (1), wherein the molar ratio (A / B / C) of the unit (A), the unit (B) and the unit (C) is the unit (A), the unit ( B) and the unit (C) as a total of 100 mol%, A / B / C = 3 to 90 mol% / 3 to 90 mol% / 3 to 90 mol%, and in a methylene chloride solution at 20 ° C. An optical film obtained by melt-extruding a polycarbonate resin having a measured specific viscosity of 0.18 to 0.34.
2. 2. The optical film as described in 1 above, wherein the polycarbonate resin has a glass transition temperature of 150 to 190 ° C.
3. 2. The optical film as described in 1 above, wherein the absolute value of the in-plane retardation value Re at a wavelength of 550 nm is 20 nm or less, and the absolute value of the thickness direction retardation value Rth is 50 nm or less.
4). ^2. The optical film as described in 1 above, wherein the number of gels is 100 / m ² or less.
5. A substrate for a touch panel using the optical film according to item 1 above.

  The polycarbonate resin of the present invention has high heat resistance, low phase difference, and good fluidity by reacting a carbonate precursor with a bisphenol compound having two fluorene structures and an aromatic dihydroxy compound at a specific composition ratio. It became possible to make it an optical film. Therefore, the industrial effect that it produces is exceptional.

Hereinafter, the present invention will be described in detail.
<Polycarbonate resin>
In the polycarbonate resin of the present invention, the main repeating unit is composed of a unit (A), a unit (B), and a unit (C).

(Unit (A))
The unit (A) is represented by the formula (A), and R ₁ and R ₂ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, preferably an alkyl group having 1 to 6 carbon atoms, and the number of carbon atoms. A cycloalkyl group having 5 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, an alkenyl group having 1 to 10 carbon atoms, or a halogen group (fluorine atom, chlorine atom, bromine atom) Etc.) is preferable. m and n each independently represents an integer of 0 to 4.

  Specifically, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, 9,9-bis (4-hydroxy-3-ethylphenyl) Fluorene, 9,9-bis (4-hydroxy-3-n-propylphenyl) fluorene, 9,9-bis (4-hydroxy-3-isopropylphenyl) fluorene, 9,9-bis (4-hydroxy-3- n-butylphenyl) fluorene, 9,9-bis (4-hydroxy-3-sec-butylphenyl) fluorene, 9,9-bis (4-hydroxy-3-tert-butylphenyl) fluorene, 9,9-bis (4-hydroxy-3-cyclohexylphenyl) fluorene, 9,9-bis (4-hydroxy-3-phenylphenyl) fluorene, etc. A carbonate units et induction. In particular, carbonate units derived from 9,9-bis (4-hydroxy-3-methylphenyl) fluorene are preferred.

(Unit (B))
The unit (B) is a carbonate unit having an aromatic structure as shown in the formula (B). In the formula (B), R ₃ and R ₄ are a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, and the number of carbon atoms. 7-13 aralkyl groups or halogen atoms are preferred. R ₃ and R ₄ are each an alkyl group having 1 to 4 carbon atoms, an aryl group having 6 to 9 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an aralkyl group having 7 to 9 carbon atoms, or a halogen atom Are more preferable, and a methyl group, a cyclohexyl group, or a phenyl group is more preferable. p and q represent the number of R ₃ and R ₄ substituted on the benzene ring, and are integers of 0 to 4.

W in the formula (B) is represented by the formula (W), and R ₅ and R ₆ are each a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group having 1 to 9 carbon atoms, An alkoxy group having 1 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an aralkyl group having 7 to 17 carbon atoms is represented. R ₅ and R ₆ may combine to form a carbocyclic or heterocyclic ring. R ₇ and R ₈ are each a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group having 1 to 9 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or 6 to 12 carbon atoms. Represents an aryl group. R ₉ is an alkylene group of 1 to 9. a represents an integer of 1 to 20, and b represents an integer of 1 to 500.

  Specifically, 4,4′-biphenol, 1,1-bis (4-hydroxyphenyl) ethane (bisphenol E), 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 2,2- Bis (4-hydroxy-3-methylphenyl) propane (bisphenol C), 2,2-bis (4-hydroxyphenyl) butane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,1 -Bis (4-hydroxyphenyl) cyclohexane (bisphenol Z), 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 2,2-bis (4-hydroxyphenyl) pentane, α, α′-bis (4-hydroxyphenyl) -m-diisopropylbenzene (bisphenol M), 1,1-bis (4-hydride) Roxyphenyl) -4-isopropylcyclohexane and the like are exemplified. Of these, bisphenol A, bisphenol Z, bisphenol C, bisphenol E, and bisphenol M are preferable from the viewpoint of heat resistance and fluidity, and bisphenol A is particularly preferable from the viewpoint of high fluidity and availability. Two or more of these may be used in combination.

(Unit (C))
The unit (C) is represented by the formula (C). In the unit (C), R ₁₀ and R ₁₁ each independently represent a hydrogen atom, a hydrocarbon group that may contain an aromatic group having 1 to 10 carbon atoms, or a halogen atom. As a hydrocarbon group, a C1-C10 alkyl group, a C5-C10 cycloalkyl group, a C6-C10 aryl group, a C7-C10 aralkyl group, a C1-C10 alkenyl group Is mentioned. Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom.

R ₁₂ and R ₁₃ each independently represent a hydrocarbon group that may contain an aromatic group having 1 to 10 carbon atoms. The hydrocarbon group is preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 1 to 4 carbon atoms, and more preferably an ethylene group.
r and k represent the number of repetitions of — (R ₁₂ —O) — and — (O—R ₁₃ ) —, respectively. r and k are each independently an integer of 1 or more, preferably an integer of 1 to 20, more preferably an integer of 1 to 12, still more preferably an integer of 1 to 8, particularly preferably 1 to 4. An integer of 1, most preferably 1. s and t each independently represent an integer of 0 to 4.

  As the unit (B), 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene, 9,9-bis [4- (3-hydroxypropoxy) phenyl] fluorene, 9,9-bis [4- (4-Hydroxybutoxy) phenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-methylphenyl] fluorene, 9,9-bis [2- (2-hydroxyethoxy) -5-methyl Phenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-ethylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-propylphenyl] fluorene, 9, 9-bis [4- (2-hydroxyethoxy) -3-isopropylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3- -Butylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-isobutylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3- (1-methylpropyl) ) Phenyl] fluorene, 9,9-bis [4- (3-hydroxypropoxy) -3-methylphenyl] fluorene, 9,9-bis [4- (4-hydroxybutoxy) -3-methylphenyl] fluorene, 9 , 9-bis [4- (2-hydroxyethoxy) -3,5-dimethylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -2,5-dimethylphenyl] fluorene, 9,9 -Bis [4- (2-hydroxyethoxy) -3,5-diethylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3 5-dipropylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5-diisopropylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5 -Di-n-butylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5-diisobutylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3 , 5-Bis (1-methylpropyl) phenyl] fluorene, 9,9-bis [4- (3-hydroxypropoxy) -3,5-dimethylphenyl] fluorene, 9,9-bis [4- (4-hydroxy) Butoxy) -3,5-dimethylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-cyclohexylphenyl] fluorene, 9, 9-bis [4- (2-hydroxyethoxy) -3-phenylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5-diphenylphenyl] fluorene, 9,9-bis [ 4- (2-hydroxyethoxy) -3-benzylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5-dibenzylphenyl] fluorene, 9,9-bis [4- ( 2-hydroxyethoxy) -3-propenylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-fluorophenyl] fluorene, and their 9,9-bis (hydroxyalkoxyphenyl) fluorene Examples are the units that are derived. Moreover, a unit derived from 9,9-bis [hydroxypoly (alkyleneoxy) phenyl] fluorene or the like in which r and k are 2 or more can be mentioned.

  Of these, 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-methylphenyl] fluorene} and the like are preferable. In particular, the unit (C1) derived from 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene (BPEF) is preferable.

(Composition ratio)
The composition ratio of the polycarbonate resin used in the present invention is such that the molar ratio (A / B / C) of units (A), units (B), and units (C) is unit (A), units (B) and A / B / C = 3 to 90 mol% / 3 to 90 mol% / 3 to 90 mol%, and A / B / C = 5 to 80 mol, where the total of units (C) is 100 mol% % / 10 to 80 mol% / 10 to 80 mol% is preferable, A / B / C = 5 to 80 mol% / 10 to 60 mol% / 20 to 80 mol% is more preferable, and A / B The range of / C = 5 to 40 mol% / 10 to 40 mol% / 40 to 70 mol% is more preferable. When a polycarbonate resin having such a composition range is formed into a film, it is preferable because the film has excellent heat resistance and fluidity and is suitable for optical applications. If the molar ratio (A / B / C) of the unit (A), the unit (B) and the unit (C) satisfies the above range, the polycarbonate resin used in the present invention is a copolymer, a blend, Alternatively, a combination thereof may be used. For example, a blend of a copolymer of unit (A) and unit (B) and a resin of unit (C) can be mentioned.

  The molar ratio is measured and calculated by proton NMR of JNM-AL400 manufactured by JEOL Ltd. The main repeating unit is a total of units (A), (B) and (C) of 60 mol% or more, preferably 70 mol% or more, more preferably 80 mol% or more, based on all repeating units. More preferably, it is 90 mol% or more, and it is especially preferable that it is substantially 100 mol%.

(Specific viscosity: η _SP )
The specific viscosity (η _SP ) of the polycarbonate resin used in the present invention is in the range of 0.18 to 0.34, preferably in the range of 0.20 to 0.33, particularly preferably 0.23. It is in the range of ~ 0.32. Within such a range, strength and the like are improved, and flow characteristics are excellent.
The specific viscosity referred to in the present invention was determined using an Ostwald viscometer from a solution obtained by dissolving 0.7 g of a polycarbonate resin in 100 ml of methylene chloride at 20 ° C.
Specific viscosity (η _SP ) = (t−t ₀ ) / t ₀
[T ₀ is methylene chloride falling seconds, t is sample solution falling seconds]

  In addition, when measuring the specific viscosity of the polycarbonate resin of this invention, it can carry out in the following way. That is, the polycarbonate resin is dissolved in 20 to 30 times the weight of methylene chloride, and the soluble component is collected by celite filtration, and then the solution is removed and dried sufficiently to obtain a solid component soluble in methylene chloride. Using a Ostwald viscometer, the specific viscosity at 20 ° C. is determined from a solution of 0.7 g of the solid dissolved in 100 ml of methylene chloride.

(Glass transition temperature: Tg)
The glass transition temperature (Tg) of the polycarbonate resin used in the present invention is preferably in the range of 150 to 190 ° C, more preferably 152 to 180 ° C, and particularly preferably 154 to 175 ° C. When Tg is equal to or higher than the lower limit, the heat resistance stability is improved, and deformation of the film in the film processing step can be suppressed. Moreover, when Tg is in the range of the upper limit or less, a high temperature is not necessary for film formation, and a special processing facility different from the conventional one is not required. Tg is estimated to be lower due to the introduction of an alkyl group. Tg is measured by using a 2910 type DSC manufactured by TA Instruments Japan Co., Ltd. at a heating rate of 20 ° C./min.

(Production method of polycarbonate resin)
The polycarbonate resin of the present invention is produced by a reaction means known per se for producing an ordinary polycarbonate resin, for example, a method of reacting a diol component with a carbonate precursor such as phosgene or carbonic acid diester. Next, basic means for these manufacturing methods will be briefly described.

In a reaction using, for example, phosgene as a carbonate precursor, the reaction is usually performed in the presence of an acid binder and a solvent. As the acid binder, for example, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide or an amine compound such as pyridine is used. As the solvent, for example, halogenated hydrocarbons such as methylene chloride and chlorobenzene are used. In order to accelerate the reaction, a catalyst such as a tertiary amine or a quaternary ammonium salt can also be used. In that case, reaction temperature is 0-40 degreeC normally, and reaction time is several minutes-5 hours. In the polycarbonate resin of the present invention, monofunctional phenols that are usually used as a terminal terminator can be used in the polymerization reaction. Particularly in the case of a reaction using phosgene as a carbonate precursor, monofunctional phenols are generally used as a terminator for controlling the molecular weight, and the resulting aromatic polycarbonate resin has a terminal monofunctional phenol. Since it is blocked by a group based on, it is superior in thermal stability as compared to those not.
Such monofunctional phenols may be used as long as they are used as an end stopper for aromatic polycarbonate resins.

  The transesterification reaction using a carbonic acid diester as a carbonate precursor is performed by a method in which an aromatic dihydroxy component in a predetermined ratio is stirred with a carbonic acid diester while heating with an inert gas atmosphere to distill the generated alcohol or phenols. . The reaction temperature varies depending on the boiling point of the alcohol or phenol produced, but is usually in the range of 120 to 300 ° C. The reaction is completed while distilling off the alcohol or phenol produced under reduced pressure from the beginning. Moreover, you may add a terminal stopper, antioxidant, etc. as needed.

  Examples of the carbonic acid diester used for the transesterification include esters such as an aryl group having 6 to 12 carbon atoms and an aralkyl group which may be substituted. Specific examples include diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate and m-cresyl carbonate. Of these, diphenyl carbonate is particularly preferred. The amount of diphenyl carbonate used is preferably 0.97 to 1.10 mol, more preferably 1.00 to 1.06 mol, per 1 mol of the total of dihydroxy compounds.

In the melt polymerization method, a polymerization catalyst can be used to increase the polymerization rate. Examples of the polymerization catalyst include alkali metal compounds, alkaline earth metal compounds, nitrogen-containing compounds, and metal compounds.
As such compounds, organic acid salts, inorganic salts, oxides, hydroxides, hydrides, alkoxides, quaternary ammonium hydroxides, and the like of alkali metals and alkaline earth metals are preferably used. It can be used alone or in combination.

  Specific examples of the alkali metal compound include sodium hydroxide, potassium hydroxide, cesium hydroxide, lithium hydroxide, sodium bicarbonate, sodium carbonate, potassium carbonate, cesium carbonate, lithium carbonate, sodium acetate, potassium acetate, acetic acid. Cesium, lithium acetate, sodium stearate, potassium stearate, cesium stearate, lithium stearate, sodium borohydride, sodium benzoate, potassium benzoate, cesium benzoate, lithium benzoate, disodium hydrogen phosphate, phosphoric acid Dipotassium hydrogen, dilithium hydrogen phosphate, disodium phenyl phosphate, disodium salt of bisphenol A, 2 potassium salt, 2 cesium salt, 2 lithium salt, sodium salt of phenol, potassium salt, cesium salt, lithium salt, etc. It is shown.

  Specific examples of the alkaline earth metal compound include magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, magnesium diacetate, calcium diacetate, and diacetic acid. Examples include strontium and barium diacetate.

  Specific examples of the nitrogen-containing compound include quaternary ammonium having an alkyl or aryl group such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and trimethylbenzylammonium hydroxide. Hydroxides are exemplified. Further, tertiary amines such as triethylamine, dimethylbenzylamine and triphenylamine, and imidazoles such as 2-methylimidazole, 2-phenylimidazole and benzimidazole are exemplified. Moreover, bases or basic salts such as ammonia, tetramethylammonium borohydride, tetrabutylammonium borohydride, tetrabutylammonium tetraphenylborate, tetraphenylammonium tetraphenylborate and the like are exemplified.

Examples of the metal compound include a zinc aluminum compound, a germanium compound, an organic tin compound, an antimony compound, a manganese compound, a titanium compound, and a zirconium compound. These compounds may be used alone or in combination of two or more.
The amount of these polymerization catalysts to be used is preferably 1 × 10 ⁻⁹ to 1 × 10 ⁻² equivalent, preferably 1 × 10 ⁻⁸ to 1 × 10 ⁻⁵ equivalent, more preferably 1 × with ^respect to 1 mol of the dihydroxy component. It is selected in the range of 10 ⁻⁷ to 1 × 10 ⁻³ equivalents.

  In addition, a catalyst deactivator can be added at a later stage of the reaction. As the catalyst deactivator to be used, a known catalyst deactivator is effectively used, and among them, sulfonic acid ammonium salt and phosphonium salt are preferable. Furthermore, salts of dodecylbenzenesulfonic acid such as tetrabutylphosphonium salt of dodecylbenzenesulfonic acid and salts of paratoluenesulfonic acid such as tetrabutylammonium salt of paratoluenesulfonic acid are preferable.

  Specific examples of sulfonic acid esters include methyl benzenesulfonate, ethyl benzenesulfonate, butyl benzenesulfonate, octyl benzenesulfonate, phenyl benzenesulfonate, methyl paratoluenesulfonate, ethyl paratoluenesulfonate, and paratoluene. Examples include butyl sulfonate, octyl p-toluenesulfonate, phenyl p-toluenesulfonate, and the like. Among these, dodecylbenzenesulfonic acid tetrabutylphosphonium salt is particularly preferable.

The amount of the catalyst deactivator used is preferably 0.5 to 50 mol per mol of the catalyst when at least one polymerization catalyst selected from alkali metal compounds and / or alkaline earth metal compounds is used. It can be used in a proportion, more preferably in a proportion of 0.5 to 10 mol, still more preferably in a proportion of 0.8 to 5 mol.
In addition, heat stabilizers, plasticizers, light stabilizers, polymerized metal deactivators, flame retardants, lubricants, antistatic agents, surfactants, antibacterial agents, ultraviolet absorbers, release agents, etc. Additives can be blended.

<Optical film>
Specifically, the optical film of the present invention includes applications such as a retardation film, a plastic substrate film, a polarizing plate protective film, an antireflection film, a brightness enhancement film, an optical disk protective film, a diffusion film, etc. A phase difference film, a polarizing plate protective film and an antireflection film are preferred.

As a method for producing an optical film, a melt extrusion method is adopted from the viewpoint of productivity.
In the melt extrusion method, a method in which a resin is melt-extruded using a T die and sent to a cooling roll is preferably used. The melt extrusion resin temperature at this time is determined from the molecular weight, Tg, melt flow characteristics, etc. of the polycarbonate resin, but is preferably in the range of 240 to 300 ° C, more preferably in the range of 250 ° C to 290 ° C. When the temperature is lower than 240 ° C., the viscosity becomes high and polymer orientation and stress strain tend to remain, and when the temperature is higher than 300 ° C., problems such as gelation due to thermal deterioration, coloring, and die line (stripe) from the T-die are likely to occur. Further, it is preferable to use a vacuum hopper that can be kept in a reduced pressure state. The degree of vacuum is preferably 10 kPa or less, more preferably 5 kPa or less, and particularly preferably 3 kPa or less.

As a thickness of an unstretched optical film, the range of 30-400 micrometers is preferable, More preferably, it is the range of 40-300 micrometers. Such an unstretched optical film is suitably used as a display substrate or a touch panel substrate.
The unstretched optical film preferably has an in-plane retardation value Re of 20 nm or less at a wavelength of 550 nm, more preferably 15 nm or less, further preferably 10 nm or less, and more preferably 5 nm or less. Is particularly preferred. Further, the absolute value of the thickness direction retardation value Rth at a wavelength of 550 nm is preferably 50 nm or less, more preferably 30 nm or less, further preferably 20 nm or less, particularly preferably 10 nm or less, Most preferably, it is 5 nm or less.
Within the above range, when used as a display substrate or a touch panel substrate, the image on the display or the touch panel is not blurred and a high-definition image can be displayed.

Such an unstretched optical film may be adjusted in phase by stretching and orientation. The machine axis direction in which the film is formed is referred to as the film forming direction or the longitudinal direction, and the direction perpendicular to the film forming direction and the film thickness direction is referred to as the lateral direction or the width direction. 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 or sequential biaxial stretching in combination thereof can be used. Moreover, although it is preferable from a point of productivity to perform continuously, you may carry out by a batch type. The stretching temperature is preferably in the range of (Tg-20 ° C) to (Tg + 50 ° C), more preferably in the range of (Tg-10 ° C) to (Tg + 30 ° C) with respect to the glass transition temperature (Tg) of the polycarbonate resin. is there. This temperature range is preferable because the molecular motion of the polymer is appropriate, relaxation due to stretching is unlikely to occur, orientation control is facilitated, and a desired in-plane retardation is easily obtained. If the stretching temperature is low, the phase difference tends to be easily developed.
It is preferable that the gel of the optical film obtained is 100 / m ² or less, more preferably 50 pieces / m ² or less. When the number of gels is within the above range, the display or touch panel can display a high-definition image when used as a display substrate or a touch panel substrate.

<Transparent conductive film for touch panel>
The optical film of the present invention is suitably used as a base film (substrate) for a transparent conductive film for a touch panel.
The transparent conductive film is obtained by providing a transparent conductive film on the low refractive index layer of the base film.
As the touch panel, a resistive touch panel and a capacitive touch panel are mainstream, but the transparent conductive film can be used for any touch panel. In particular, the transparent conductive film is suitable for a capacitive touch panel.

The transparent conductive film of the transparent conductive film of the capacitive touch panel is usually patterned in a predetermined pattern. The patterning of the transparent conductive film is performed by etching the transparent conductive film.
A transparent conductive film having a patterned transparent conductive film has a pattern portion (a portion where the transparent conductive film remains without being etched (conductive portion)) and a non-pattern portion (the transparent conductive film is etched). The part of the pattern is visually recognized due to the difference in reflectance and transmittance from the removed part (non-conductive part) or the color tone of the pattern part and the non-pattern part, so-called “bone appearance” occurs. The visibility of the transparent conductive film is reduced. This “bone appearance” problem is reduced by using the base film of the present invention.

As a material of the transparent conductive film, a known material used for a transparent conductive film can be used. Examples thereof include metal oxides such as tin oxide, indium oxide, antimony oxide, zinc oxide, ITO (indium tin oxide) and ATO (antimony tin oxide), metal nanowires such as silver nanowires, and carbon nanotubes. Among these, ITO is preferably used.
The thickness of the transparent conductive film is preferably smaller from the viewpoint of improving the visibility of the transparent conductive film, specifically 40 nm or less, more preferably 30 nm or less, still more preferably 25 nm or less, and particularly preferably 20 nm or less. . The lower limit of the thickness of the transparent conductive film is preferably 5 nm or more, more preferably 7 nm or more, and particularly preferably 10 nm or more from the viewpoint of securing a low-resistance transparent conductive film.

The surface resistance value of the transparent conductive film is preferably 1000Ω / □ or less, and preferably 500Ω / □ or less.
The refractive index of the transparent conductive film is preferably 1.81 or more. Further, the refractive index of the transparent conductive film is preferably 1.85 or more, more preferably 1.90 or more. The upper limit is preferably 2.20 or less, and more preferably 2.10 or less.
It does not specifically limit as a formation method of a transparent conductive film, A conventionally well-known method can be used. Specifically, for example, a dry process such as a vacuum deposition method, a sputtering method, or an ion plating method can be used.

  The transparent conductive film is preferably patterned. The patterning of a transparent conductive film can form various patterns according to the use to which a transparent conductive film is applied. Note that the pattern portion and the non-pattern portion are formed by patterning the transparent conductive film. Examples of the pattern shape of the pattern portion include a stripe shape, a lattice shape, or a combination thereof. Specifically, for example, there are patterns disclosed in JP-A-2006-344163, JP-A-2011-128896, and the like.

The patterning of the transparent conductive film is generally performed by etching. For example, an etching resist film having a predetermined pattern is formed on the transparent conductive film by a photolithography method, a laser exposure method, or a printing method, and then etched to pattern the transparent conductive film.
A conventionally well-known thing is used as an etching liquid. For example, inorganic acids such as hydrogen chloride, hydrogen bromide, sulfuric acid, nitric acid and phosphoric acid, organic acids such as acetic acid, and mixtures thereof, and aqueous solutions thereof are used.

  Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto. In the examples, “parts” means “parts by weight”. The resins used and the evaluation methods used in the examples are as follows.

1. Polymer composition ratio (NMR)
The polymer composition ratio (molar ratio) was calculated by proton NMR of JNM-AL400 manufactured by JEOL Ltd.

2. Specific viscosity The viscosity was determined using an Ostwald viscometer from a solution of 0.7 g of polycarbonate resin in 100 ml of methylene chloride at 20 ° C.
Specific viscosity (η _SP ) = (t−t ₀ ) / t ₀
[T ₀ is methylene chloride falling seconds, t is sample solution falling seconds]

3. Glass transition temperature Using a thermal analysis system DSC-2910 manufactured by TA Instruments Co., Ltd. using 8 mg of polycarbonate resin, in a nitrogen atmosphere (nitrogen flow rate: 40 ml / min) in accordance with JIS K7121 Temperature increase rate: Measured under conditions of 20 ° C./min.

4). Number of gels Using the color 3D laser microscope, the number of gels obtained by converting the number of gels having interference fringes having a major axis diameter of 300 μm or more existing in 500 mm × 1000 mm into 1 m ² of the film. .

5. Phase difference measurement The optical film obtained in the Example was measured using Spectroellipometer M-220 manufactured by JASCO Corporation.

6). Haze
Using the optical film obtained in the example, a turbidimeter NDH-2000 type (manufactured by Nippon Denshoku Industries Co., Ltd.) was used, and the haze of the film was measured according to JIS K7105.

[Example 1]
<Manufacture of polycarbonate resin>
9,9-bis (4-hydroxy-3-methylphenyl) fluorene (hereinafter abbreviated as BCF) 194.6 parts, 9-bis [4- (2-hydroxyethoxy) phenyl] fluorene (hereinafter abbreviated as BPEF) 901. 8 parts, 2,2-bis (4-hydroxyphenyl) propane (hereinafter sometimes abbreviated as “BPA”) (hereinafter abbreviated as BPA) 195.6 parts, diphenyl carbonate 749.7 parts and tetramethylammonium as a catalyst Hydroxide 3.6 × 10 ⁻³ parts and sodium hydrogen carbonate 1.6 × 10 ⁻⁴ parts were heated to 180 ° C. in a nitrogen atmosphere and melted. Thereafter, the degree of vacuum was adjusted to 13.4 kPa over 30 minutes. Thereafter, the temperature was raised to 270 ° C. at a rate of 20 ° C./hr and held at that temperature for 10 minutes, and then the degree of vacuum was reduced to 133 Pa or less over 1 hour. The reaction was carried out under stirring for a total of 6 hours.
After completion of the reaction, 1.5 times mole of the catalyst amount of tetrabutylphosphonium salt of dodecylbenzene sulfonate was added to deactivate the catalyst, and then discharged from the bottom of the reaction tank under nitrogen pressure and cooled in a water tank while being pelletized. To obtain pellets.
<Manufacture of optical film>
Next, a T-die having a width of 650 mm was attached to a 40 mmφ single-screw extruder, and the obtained polycarbonate resin was melt-formed at 280 ° C. to obtain a transparent unstretched film having a thickness of 50 μm. The optical film obtained was measured for retardation, gel number, and haze. The results are shown in Table 1.

[Example 2]
<Manufacture of polycarbonate resin>
Except for using 129.7 parts of BCF, 901.8 parts of BPEF, and 234.7 parts of BPA, the same operation as in Example 1 was performed to obtain a polycarbonate resin. The specific viscosity and glass transition temperature of the pellets were measured and listed in Table 1.
<Manufacture of optical film>
Next, a film was formed from the obtained polycarbonate resin in the same manner as in Example 1, and retardation measurement, gel number, and haze were measured. The results are shown in Table 1.

[Example 3]
<Manufacture of polycarbonate resin>
Except for using 259 parts of BCF, 751.5 parts of BPEF, and 234.7 parts of BPA, the same operation as in Example 1 was performed to obtain a polycarbonate resin. The specific viscosity and glass transition temperature of the pellets were measured and listed in Table 1.
<Manufacture of optical film>
Next, a film was formed from the obtained polycarbonate resin in the same manner as in Example 1, and retardation measurement, gel number, and haze were measured. The results are shown in Table 1.

[Example 4]
<Manufacture of polycarbonate resin>
Except for using BCF389.1 parts, BPEF751.5 parts, and BPA156.5 parts, the same operation as in Example 1 was performed to obtain a polycarbonate resin. The specific viscosity and glass transition temperature of the pellets were measured and listed in Table 1.
<Manufacture of optical film>
Next, a film was formed from the obtained polycarbonate resin in the same manner as in Example 1, and retardation measurement, gel number, and haze were measured. The results are shown in Table 1.

[Example 5]
<Manufacture of polycarbonate resin>
Except for using 129.7 parts of BCF, 901.8 parts of BPEF, and 234.7 parts of BPA, the same operation as in Example 1 was performed to obtain a polycarbonate resin. The specific viscosity and glass transition temperature of the pellets were measured and listed in Table 1.
<Manufacture of optical film>
Next, a film was formed from the obtained polycarbonate resin in the same manner as in Example 1, and retardation measurement, gel number, and haze were measured. The results are shown in Table 1.

[Comparative Example 1]
<Manufacture of polycarbonate resin>
Except that BCF was not used as BPEF 901.7 parts and BPA 312.9 parts, the same operation as in Example 1 was performed to obtain a polycarbonate resin. The specific viscosity and glass transition temperature of the pellets were measured and listed in Table 1.
<Manufacture of optical film>
Next, a film was formed from the obtained polycarbonate resin in the same manner as in Example 1, and retardation measurement, gel number, and haze were measured. The results are shown in Table 1.

[Comparative Example 2]
<Manufacture of polycarbonate resin>
Except that BPEF was not used as BCF389.1 parts and BPA547.6 parts, the same operation as in Example 1 was performed to obtain a polycarbonate resin. The specific viscosity and glass transition temperature of the pellets were measured and listed in Table 1.
<Manufacture of optical film>
Next, a film was formed from the obtained polycarbonate resin in the same manner as in Example 1, and retardation measurement, gel number, and haze were measured. The results are shown in Table 1.

[Comparative Example 3]
<Manufacture of polycarbonate resin>
Except that BPA was not used as BCF389.1 parts and BPEF1052.1 parts, the same operation as in Example 1 was performed to obtain a polycarbonate resin. The specific viscosity and glass transition temperature of the pellets were measured and listed in Table 1.
<Manufacture of optical film>
Next, a film was formed from the obtained polycarbonate resin in the same manner as in Example 1, and retardation measurement, gel number, and haze were measured. The results are shown in Table 1.

[Comparative Example 4]
<Manufacture of polycarbonate resin>
Except for the final polymerization temperature of 285 ° C., the same operation as in Example 3 was performed to obtain a polycarbonate resin. The specific viscosity and glass transition temperature of the pellets were measured and listed in Table 1.
<Manufacture of optical film>
Next, a film was formed from the obtained polycarbonate resin in the same manner as in Example 1, and retardation measurement, gel number, and haze were measured. The results are shown in Table 1.

  The optical film of the present invention is useful as a substrate for a transparent conductive film.

Claims (5)

The main repeating unit is the following formula

[In Formula (A), R ₁ and R ₂ each independently represent a hydrogen atom, a hydrocarbon group that may contain an aromatic group having 1 to 10 carbon atoms, or a halogen atom, and m and n each independently And represents an integer of 0 to 4. ]
Unit (A) represented by the following formula

[In the formula (B), R ₃ and R ₄ are each independently a hydrogen atom, a hydrocarbon group which may contain an aromatic group having 1 to 9 carbon atoms or a halogen atom, and p and q are each independently Represents an integer of 0 to 4. W is a single bond or the following formula (W)

Where R ₅ and R ₆ are a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group having 1 to 9 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and a carbon atom, respectively. It represents an aryl group having 6 to 12 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an aralkyl group having 7 to 17 carbon atoms. R ₅ and R ₆ may combine to form a carbocyclic or heterocyclic ring. R ₇ and R ₈ are each a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group having 1 to 9 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or 6 to 12 carbon atoms. Represents an aryl group. R ₉ is an alkylene group of 1 to 9. a represents an integer of 1 to 20, and b represents an integer of 1 to 500. ]
Unit (B) represented by the following formula

[Wherein, R ₁₀ and R ₁₁ each independently represent a hydrogen atom, a hydrocarbon group which may contain an aromatic group having 1 to 10 carbon atoms, or a halogen atom, and R ₁₂ and R ₁₃ each independently represent A hydrocarbon group which may contain an aromatic group having 1 to 10 carbon atoms, s and t each independently represent an integer of 0 to 4, and r and k each independently represents 1 or more. Indicates an integer. ]
A polycarbonate resin containing a unit (C) represented by the formula (1), wherein the molar ratio (A / B / C) of the unit (A), the unit (B) and the unit (C) is the unit (A), the unit ( B) and the unit (C) as a total of 100 mol%, A / B / C = 3 to 90 mol% / 3 to 90 mol% / 3 to 90 mol%, and in a methylene chloride solution at 20 ° C. An optical film obtained by melt-extruding a polycarbonate resin having a measured specific viscosity of 0.18 to 0.34.   The optical film according to claim 1, wherein the polycarbonate resin has a glass transition temperature of 150 to 190 ° C.   The optical film according to claim 1, wherein the absolute value of the in-plane retardation value Re at a wavelength of 550 nm is 20 nm or less, and the absolute value of the thickness direction retardation value Rth is 50 nm or less. The optical film according to claim 1, wherein the number of gels is 100 / m ² or less.   A touch panel substrate using the optical film according to claim 1.