JP2008023981A - Thermoplastic film, its manufacturing method, polarizing plate, optical compensation film, reflection preventing film and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a thermoplastic film suppressed in the occurrence of warpage after the long-term elapse of time. <P>SOLUTION: When the thermoplastic film is manufactured through a process for discharging a molten thermoplastic resin to the surface of a casting drum from a die in a sheetlike state, the thermoplastic resin discharged in a sheetlike form from a die is stretched so that the degree of elongation in a film forming direction of the thermoplastic resin becomes 1-25% during a period wherein the thermoplastic resin discharged in the sheetlike state from the die is cooled from Tg+40°C to Tg. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a method for producing a thermoplastic film, a thermoplastic film, and a polarizing plate, an optical compensation film, an antireflection film and a liquid crystal display device using the same, and particularly, when used for a laminated polarizing plate, warpage and peeling. The present invention relates to an improved thermoplastic film production method and thermoplastic film, and a polarizing plate, an optical compensation film, an antireflection film and a liquid crystal display device using the same.

  Conventionally, as a method for producing a cellulose acylate film used in a liquid crystal display device or the like, cellulose acylate is mainly dissolved in a chlorinated organic solvent such as dichloromethane, and this is cast on a substrate and dried. A solution casting method to form a film was carried out. Dichloromethane has been conventionally used as a good solvent for cellulose acylate, and since it has a low boiling point (about 40 ° C.), it has the advantage of being easy to dry in the film formation and drying process of the production process, and is preferably used. ing.

  In recent years, from the viewpoint of environmental protection, it has been required to significantly reduce leakage of a chlorinated organic solvent having a low boiling point even in a handling process in a closed facility. For this reason, for example, a thorough closed system is used to prevent leakage from the system, and even if a leak occurs, a gas absorption tower is installed before being released to the outside air, and an organic solvent is adsorbed and treated. Furthermore, most organic solvents can be prevented from being discharged by performing combustion with thermal power or decomposition of a chlorinated organic solvent with an electron beam before discharging. However, it has not reached complete non-emission and further research is needed.

Therefore, as a film forming method that does not use an organic solvent, a method of melt-forming a specific cellulose acylate has been proposed (for example, see Patent Document 1). In this method, the carbon chain of the ester group of cellulose acylate is lengthened to lower the melting point, thereby facilitating melt film formation. Specifically, melt film formation is enabled by changing from cellulose acetate to cellulose propionate or cellulose butyrate.
It is also considered to use a saturated norbornene film as a film for a liquid crystal display panel (for example, see Patent Document 2). Such a saturated norbornene film can also be formed by a melt film forming method, and the environmental load can be reduced.

However, when a polarizing plate is produced using an optical film made of these thermoplastic resins (cellulose acylate, saturated norbornene) and incorporated in a liquid crystal display device, the thermoplastic film warps after a long period of time, which causes heat. It has become clear that peeling occurs between the plastic film and the polarizer, and an improvement thereof has been desired.
JP 2000-352620 A JP 2005-134768 A

  In order to solve the above-described problems of the prior art, an object of the present invention is to provide a thermoplastic film that suppresses warpage after a long period of time and a method for producing the same. Another object of the present invention is to provide a polarizing plate, an optical compensation film, an antireflection film and a liquid crystal display device using the thermoplastic film.

（上式において、Ｔ１は前記熱可塑性樹脂がＴｇ＋４０℃に冷却された時点おける、製膜方向に設けられたフィルム上の２定点間の距離を表し、Ｔ２は前記熱可塑性樹脂がＴｇ℃に冷却された時点おける前記２定点間の距離を表し、Ｔ０は製膜された熱可塑性樹脂の２５℃における前記２定点間の距離を表す。）
（２）前記ダイ出口の前記熱可塑性樹脂の溶融粘度が１００Ｐａ・ｓ〜２０００Ｐａ・ｓであることを特徴とする（１）に記載の熱可塑性フィルムの製造方法。
（３）前記キャスティングドラム上でタッチロールを用いて前記熱可塑性樹脂を製膜することを特徴とする（１）または（２）に記載の熱可塑性フィルムの製造方法。
（４）６０℃で５００時間経時させたときの全方向における寸法変化量が１％以下であることを特徴とする熱可塑性フィルム。
（５）面内レターデーション（Ｒｅ）が０ｎｍ〜２５ｎｍであり、且つ、厚み方向レターデーション（Ｒｔｈ）が０ｎｍ〜２５ｎｍであることを特徴とする（４）に記載の熱可塑性フィルム。
（６）下記式（１）および（２）を満足する組成のセルロースアシレート樹脂を含むことを特徴とする（４）または（５）に記載の熱可塑性フィルム。
式（１）：２．５≦Ａ＋Ｂ＜３．０
式（２）：１．２５≦Ｂ＜３
（式中、Ａはアセテート基の置換度を表し、Ｂは、プロピオネート基、ブチレート基およびペンタノイル基の置換度の総和を表す。）
（７）下記式（Ｔ−１）および（Ｔ−２）を満たす組成を有するセルロースアシレートを含むことを特徴とする（４）または（５）に記載の熱可塑性フィルム。
式（Ｔ−１）：２．５≦Ａ＋Ｃ＜３．０
式（Ｔ−２）：０．１≦Ｃ＜２
（式中、Ａは、アセテート基の置換度を示し、Ｃは置換もしくは無置換の芳香族アシル基を示す。）
（８）飽和ノルボルネン樹脂を含むことを特徴とする（４）または（５）に記載の熱可塑性フィルム。
（９）（１）〜（３）のいずれか１項に記載の熱可塑性フィルムの製造方法によって製造されたことを特徴とする（４）〜（８）のいずれか１項に記載の熱可塑性フィルム。
（１０）残留溶剤量が０．０１質量％以下であることを特徴とする（４）〜（９）のいずれか１項に記載の熱可塑性フィルム。
（１１）延伸処理が施され、面内レターデーション（Ｒｅ）と厚み方向レターデーション（Ｒｔｈ）が下記（３）および（４）を満足することを特徴とする（４）〜（１０）のいずれか１項に記載の熱可塑性フィルム。
式（３）：０ｎｍ≦Ｒｅ≦１５０ｎｍ
式（４）：０ｎｍ≦Ｒｔｈ≦３００ｎｍ
（１２）（４）〜（１１）のいずれか１項に記載の熱可塑性フィルムを、縦横比Ｌ／Ｗが２を超え５０以下、或いは０．０１〜０．３で延伸したことを特徴とする熱可塑性フィルム。
（１３）（４）〜（１２）のいずれか１項に記載の熱可塑性フィルムを、横延伸前に延伸温度より１℃〜５０℃高い温度で予熱することを特徴とする熱可塑性フィルム。
（１４）（４）〜（１３）のいずれか１項に記載の熱可塑性フィルムを、横延伸後に延伸温度より１℃〜５０℃低い温度で熱処理することを特徴とする熱可塑性フィルム。
（１５）（４）〜（１４）のいずれか１項に記載の熱可塑性フィルムを、前記横延伸後、または、縦延伸を行った後で、（Ｔｇ−５０）℃〜（Ｔｇ＋３０）℃で、０．１ｋｇ／ｍ〜２０ｋｇ／ｍの張力で搬送しながら熱緩和したことを特徴とする熱可塑性フィルム。
（１６）偏光子に、（４）〜（１５）のいずれか１項に記載の熱可塑性フィルムを少なくとも１層積層したことを特徴とする偏光板、光学補償フィルムまたは反射防止フィルム。
（１７）（４）〜（１５）のいずれか１項に記載の熱可塑性フィルム、（１６）に記載の偏光板、光学補償フィルムおよび反射防止フィルムの少なくとも一つを用いたことを特徴とする液晶表示装置。
（１８）溶融した熱可塑性樹脂をダイからキャスティングドラム上に吐出して製膜する熱可塑性フィルムの製造方法であって、
ダイから吐出された前記熱可塑性樹脂を延伸する延伸工程と、前記熱可塑性樹脂がＴｇ＋４０℃からＴｇ℃に冷却される間に（Ｔｇは前記熱可塑性樹脂のガラス転移温度である）、下記式（Ａ）で示される製膜方向の延伸度が２５％以下となるように制御する延伸度制御工程とを有することを特徴とする熱可塑性フィルムの製造方法。

As a result of intensive investigations by the inventors under the above-mentioned problems, in a method for producing a thermoplastic resin film obtained by forming a film by discharging a molten thermoplastic resin from a die onto a casting drum in a sheet form, Tg + 40 ° C. to Tg ° C. It has been found that the expression of Re and Rth can be suppressed by controlling the degree of stretching in the film forming direction to 25% or less during cooling. In particular, low Re and low Rth thermoplastic films (for example, those having in-plane retardation (Re) of 0 nm to 25 nm and thickness direction retardation (Rth) of 0 nm to 25 nm) can be obtained. I found.
That is, as shown in FIG. 8, in the melt film formation, when the thermoplastic resin discharged from the die is cooled to Tg + 40 ° C. to Tg ° C., the finally obtained thermoplastic film is stretched in the film forming direction, Re and Rth are expressed. However, it has been found that at temperatures higher than Tg + 40 ° C., Re and Rth of the thermoplastic film are not expressed even by stretching in the film forming direction. Therefore, the present inventors have controlled the degree of stretching in the film forming direction to 25% or less so as not to cause stretching in the film forming direction at Tg + 40 ° C. to Tg ° C. as much as possible, thereby reducing low Re and low Rth thermoplasticity. It found out that a film was obtained and completed the manufacturing method of the said invention.
Specifically, it was achieved by means.
(1) A method for producing a thermoplastic film in which a molten thermoplastic resin is formed from a die through a step of discharging it into a sheet on a casting drum,
While the thermoplastic resin discharged in sheet form from the die is cooled from Tg + 40 ° C. to Tg ° C. (Tg is the glass transition temperature of the thermoplastic resin), the film formation represented by the following formula (A) A method for producing a thermoplastic film, wherein the thermoplastic resin is discharged onto a casting drum while controlling the degree of stretching in a direction to be 25% or less.

(In the above formula, T1 represents the distance between two fixed points on the film provided in the film forming direction when the thermoplastic resin is cooled to Tg + 40 ° C., and T2 is the temperature at which the thermoplastic resin is cooled to Tg ° C. (T0 represents the distance between the two fixed points at 25 ° C. of the formed thermoplastic resin.)
(2) The method for producing a thermoplastic film according to (1), wherein the thermoplastic resin at the outlet of the die has a melt viscosity of 100 Pa · s to 2000 Pa · s.
(3) The method for producing a thermoplastic film according to (1) or (2), wherein the thermoplastic resin is formed on the casting drum by using a touch roll.
(4) A thermoplastic film characterized by having a dimensional change in all directions of 1% or less when aged at 60 ° C. for 500 hours.
(5) The thermoplastic film according to (4), wherein the in-plane retardation (Re) is 0 nm to 25 nm and the thickness direction retardation (Rth) is 0 nm to 25 nm.
(6) The thermoplastic film according to (4) or (5), comprising a cellulose acylate resin having a composition satisfying the following formulas (1) and (2).
Formula (1): 2.5 <= A + B <3.0
Formula (2): 1.25 ≦ B <3
(In the formula, A represents the degree of substitution of the acetate group, and B represents the sum of the degree of substitution of the propionate group, butyrate group, and pentanoyl group.)
(7) The thermoplastic film as described in (4) or (5), comprising cellulose acylate having a composition satisfying the following formulas (T-1) and (T-2).
Formula (T-1): 2.5 <= A + C <3.0
Formula (T-2): 0.1 ≦ C <2
(In the formula, A represents the degree of substitution of the acetate group, and C represents a substituted or unsubstituted aromatic acyl group.)
(8) The thermoplastic film according to (4) or (5), comprising a saturated norbornene resin.
(9) The thermoplastic material according to any one of (4) to (8), which is produced by the method for producing a thermoplastic film according to any one of (1) to (3). the film.
(10) The thermoplastic film as described in any one of (4) to (9), wherein the residual solvent amount is 0.01% by mass or less.
(11) Any one of (4) to (10), wherein a stretching treatment is performed, and in-plane retardation (Re) and thickness direction retardation (Rth) satisfy the following (3) and (4): The thermoplastic film of Claim 1.
Formula (3): 0 nm ≦ Re ≦ 150 nm
Formula (4): 0 nm ≦ Rth ≦ 300 nm
(12) The thermoplastic film according to any one of (4) to (11) is stretched at an aspect ratio L / W of more than 2 and 50 or less, or 0.01 to 0.3. Thermoplastic film.
(13) A thermoplastic film characterized in that the thermoplastic film according to any one of (4) to (12) is preheated at a temperature 1 ° C. to 50 ° C. higher than the stretching temperature before transverse stretching.
(14) A thermoplastic film characterized by heat-treating the thermoplastic film according to any one of (4) to (13) at a temperature lower by 1 ° C to 50 ° C than the stretching temperature after transverse stretching.
(15) After the transverse stretching or longitudinal stretching of the thermoplastic film according to any one of (4) to (14), at (Tg-50) ° C. to (Tg + 30) ° C. A thermoplastic film characterized by heat relaxation while being conveyed with a tension of 0.1 kg / m to 20 kg / m.
(16) A polarizing plate, an optical compensation film, or an antireflection film obtained by laminating at least one layer of the thermoplastic film according to any one of (4) to (15) on a polarizer.
(17) At least one of the thermoplastic film according to any one of (4) to (15), the polarizing plate, the optical compensation film, and the antireflection film according to (16) is used. Liquid crystal display device.
(18) A method for producing a thermoplastic film in which a molten thermoplastic resin is discharged from a die onto a casting drum to form a film,
During the stretching step of stretching the thermoplastic resin discharged from the die, and while the thermoplastic resin is cooled from Tg + 40 ° C. to Tg ° C. (Tg is the glass transition temperature of the thermoplastic resin), the following formula ( A method for producing a thermoplastic film, comprising: a stretching degree control step for controlling the stretching degree in the film forming direction indicated by A) to be 25% or less.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method and thermoplastic film of a thermoplastic film which suppressed generation | occurrence | production of the curvature after long-term aging, a polarizing plate, an optical compensation film, an antireflection film, and a liquid crystal display device using the same are provided. be able to.

  As a result of diligent study, the present inventors have clarified that the cause of warping of the polarizing plate or the like is a dimensional change of the thermoplastic film. That is, the cause of the warpage of the polarizing plate or the like is that the residual strain contained in the thermoplastic film laminated with the polarizer is gradually released over a long period of time, resulting in a dimensional change of the film that occurs and poor adhesion and polarization plate warpage. It became clear that it occurred. Further, the present inventors have found that a change in dimensions and retardation before and after 500 hours at a high temperature (60 ° C.) can be used as a method for simulating such aging at normal temperature and long time. Such suppression of residual strain is achieved by a casting drum (hereinafter referred to as “melt”), which is a molten thermoplastic resin extruded from a die (hereinafter sometimes referred to as “melt”). It has been found that it can be achieved by precisely controlling until solidification on the CD).

  The manufacturing method of the present invention is a method for manufacturing a thermoplastic film (a manufacturing method by a melt film forming method) for forming a film through a step of discharging a molten thermoplastic resin from a die onto a casting drum in a sheet form, The thermoplastic resin is stretched so that the degree of stretching in the film forming direction is 25% or less while the thermoplastic resin discharged in a sheet form from the die in the process is cooled from Tg + 40 ° C. to Tg. And Here, “Tg” means the glass transition temperature of the thermoplastic resin. The degree of stretching in the film forming direction is calculated according to the above formula (A), and a specific measuring method will be described later.

  That is, in the thermoplastic film production method of the present invention, in the melt film forming step, the film forming direction (hereinafter referred to as “MD”) while the melt is cooled from Tg + 40 ° C. to Tg on the casting drum from the die. The degree of stretching is 25% or less. Ideally, the degree of stretching is preferably controlled to 0%, but in practice, it may be controlled to 1% to 25%, more preferably 2% to 22%, and even more preferably 3% to 20%. Control.

上記延伸工程では、溶融状態の樹脂が膜厚を調整するために、３００μｍ以下（好ましくは１０〜２００μｍ、より好ましくは２０〜１５０μｍ）の薄いフィルムに延伸される。この溶融樹脂延伸工程では、樹脂の温度はＴｇ＋４０℃を超える温度に保たれていることが好ましい。なお、この溶融樹脂延伸工程では、熱可塑性樹脂の表裏両面にヒーターなどの加熱手段を設置し、樹脂の温度をＴｇ＋４０℃を超える温度に制御することが好ましい。またこの延伸工程を経て、熱可塑性樹脂はＴｇ＋４０℃以下になる。
その後、延伸度制御工程では、熱可塑性樹脂がＴｇ＋４０℃からＴｇ℃に冷却される間に、上記式（Ａ）で示される製膜方向の延伸度が２５％以下となるように制御される。この延伸度の制御により、不要なレターデーションの発現が抑制され、低レターデーションの熱可塑性フィルムを得ることができる。なお、式（Ａ）では、分母をＴ０としているが、分母をＴ１として延伸度を規定してもよい。分母をＴ１としたときの延伸度は、分母をＴ０としたときの延伸度と同等の範囲に制御すればよい。 The melt extruded from the slit of the die reaches the casting drum CD while being reduced in thickness, and is cooled and solidified. Usually, the thermoplastic film as in the present invention is required to be a thin film of 300 μm or less. However, since it is difficult to accurately control such a thin thickness with a die slit, first, a thermoplastic resin is extruded from a wider die slit, and the CD is rotated at a speed faster than the extrusion speed to form a sheet. The film is made thin by taking up the thermoplastic resin. However, in such a film forming method, the melt is stretched in the MD direction simultaneously with the thickness reduction, which causes a residual strain. Such residual strain is gradually released over time, which causes dimensional changes and retardation changes. Residual strains accumulate particularly significantly during cooling from Tg + 40 ° C. to Tg. This is because the residual strain is less likely to accumulate at temperatures above Tg + 40 ° C., and the residual strain is difficult to accumulate at temperatures below Tg, while the residual strain is difficult to accumulate at temperatures below Tg. is there. Therefore, it is important to control the degree of stretching in the film forming direction (MD) between Tg + 40 ° C. and Tg according to the present invention.
That is, the manufacturing method of the present invention includes a stretching step of stretching a thermoplastic resin discharged in a sheet form from a die, and while the thermoplastic resin is cooled from Tg + 40 ° C. to Tg ° C. (Tg is the thermoplastic resin). And a stretching degree control step for controlling the stretching degree in the film forming direction represented by the following formula (A) to be 25% or less.

In the stretching step, the molten resin is stretched into a thin film of 300 μm or less (preferably 10 to 200 μm, more preferably 20 to 150 μm) in order to adjust the film thickness. In this molten resin stretching step, the temperature of the resin is preferably maintained at a temperature exceeding Tg + 40 ° C. In this molten resin stretching step, it is preferable to install heating means such as a heater on both the front and back surfaces of the thermoplastic resin and control the temperature of the resin to a temperature exceeding Tg + 40 ° C. Further, through this stretching step, the thermoplastic resin becomes Tg + 40 ° C. or lower.
Thereafter, in the stretching degree control step, while the thermoplastic resin is cooled from Tg + 40 ° C. to Tg ° C., the stretching degree in the film forming direction represented by the above formula (A) is controlled to be 25% or less. By controlling the degree of stretching, the development of unnecessary retardation can be suppressed, and a low retardation thermoplastic film can be obtained. In the formula (A), the denominator is T0, but the degree of stretching may be defined by using the denominator as T1. The degree of stretching when the denominator is T1 may be controlled in a range equivalent to the degree of stretching when the denominator is T0.

  For this reason, in the present invention, in order to reduce the accumulation of residual strain resulting from resin deformation during cooling from Tg + 40 ° C. to Tg between the die and the CD, for example, the molten resin is cooled from the die exit temperature to Tg + 40 ° C. It is important that most of the stretching that should be performed on the resin is performed as needed during the period until it is rapidly cooled to Tg or less. FIG. 1 is a schematic diagram for explaining this. In the figure, 1 is a die exit, and A indicates a temperature region of Tg + 40 ° C. or higher. Here, as a result of stretching in a temperature region of Tg + 40 ° C. or higher, a target thickness is achieved at position 2. The target thickness here means a thickness that achieves a desired thickness when cooled to room temperature. After reaching position 2, it is rapidly cooled to a temperature below Tg in region B. By this rapid cooling, the film thickness becomes sharply thin. This step can be achieved by appropriately combining the following methods.

(1) Measurement of stretched position of molten resin The melt thickness between the die and the CD is continuously measured, and the position 2 at which the target thickness is obtained is specified. The thickness change can be performed by actually measuring the film thickness change in real time with a film thickness meter etc. during transportation, and any film thickness meter such as a contact type or non-contact type may be used for the measurement It is preferable to use a non-contact type, particularly an optical film thickness meter.

(2) Thermal insulation of the molten resin in the region A The melt on the upstream side (die side) from the position 2 where the target thickness is obtained is maintained at Tg + 40 ° C. or higher. For this, any method may be employed, such as resin heating with a heater or warm air, or a method in which the resin conveying portion is covered with a heat insulating material to raise the conveying atmosphere. When warming with warm air, it is preferable to keep it to such an extent that there is no fear of resin deformation due to wind pressure. A method of heating the melt resin with a heater is preferable because it is easy to confirm the state of the resin during film formation.

(3) Cooling of the molten resin in the region B The melt on the downstream side (conveying direction) from the position 2 having the target thickness is cooled to Tg or less. This cooling is preferably rapid cooling. As this method, any method may be used as long as it can rapidly cool from Tg + 40 ° C. to Tg or less. For example, cooling with a casting drum set to Tg or less, cooling with cold air, or a method of immersing in a refrigerant set to Tg or less to cool the resin can be considered. Among these, a method of cooling the melt using a casting drum set to Tg or less is preferable. When a plurality of (for example, three) casting drums are used, the initial casting drum is set to Tg or less to cool the melt to suppress distortion generated during film formation.

  In the above-described method for producing a thermoplastic film of the present invention, a thermoplastic film satisfying the following physical properties can be produced.

(i) In-plane retardation (Re): 0 nm to 25 nm, more preferably 0 nm to 20
nm, more preferably 0 nm to 15 nm. When Re is in the range of 0 nm to 25 nm, light leakage when processed into a polarizing plate can be reduced.
(ii) Thickness direction retardation (Rth): 0 nm to 25 nm, more preferably 0 nm to 20 nm, still more preferably 0 nm to 15 nm. When Rth is in the range of 0 nm to 25 nm, light leakage when processed into a polarizing plate can be reduced.
(iii) Dimensional change amount is 1% under 60 ° C thermo conditions (aging at 60 ° C for 500 hours)
Hereinafter, it is more preferably 0.4% or less, and further preferably 0.2% or less. When the dimensional change rate is 1% or less, warpage and peeling at the time of polarizing plate processing can be reduced.
(iv) Moreover, as a film thickness of a thermoplastic film, 35 micrometers-400 micrometers are preferable, 80 micrometers-300 micrometers are more preferable, Especially preferably, they are 80 micrometers-120 micrometers.

Among the above, the thermoplastic film of the present invention is characterized in that the dimensional change in all directions is 1% or less under the thermo-condition at 60 ° C. When the amount of dimensional change exceeds 1%, warpage occurs over time, and peeling due to warpage or the like occurs when a polarizing plate is attached to a polarizer or the like. The amount of dimensional change is preferably 0.4% or less, and more preferably 0.2% or less.
The thermoplastic film of the present invention preferably satisfies the physical properties (i), (ii) and (iv) in addition to the dimensional change rate. In particular, the thermoplastic film of the present invention preferably has an in-plane retardation (Re) of 0 nm to 25 nm and a thickness direction retardation (Rth) of 0 nm to 25 nm.

Hereinafter, the present invention will be described in detail. Although a cellulose acylate film using a cellulose acylate resin will be mainly described as an example, a thermoplastic film using another thermoplastic resin can also be adopted according to this.
《Thermoplastic film》
Hereinafter, the present invention will be described in order.
Preferred examples of the thermoplastic film of the present invention include a transparent thermoplastic film composed of at least one selected from cellulose acylate resins, polycarbonate resins, and saturated norbornene resins. Of these, cellulose acylate resins and saturated norbornene resins are preferred.

<Cellulose acylate resin>
The cellulose acylate resin that can be used as the thermoplastic resin in the present invention preferably has a composition satisfying the following formulas (1) and (2) (wherein A represents the substitution degree of the acetate group, B represents the sum of the substitution degrees of the propionate group, butyrate group and pentanoyl group.)

Formula (1): 2.5 <= A + B <3.0
Formula (2): 1.25 ≦ B <3
More preferably,
When 1/2 or more of B is a propionate group 2.6 ≦ A + B ≦ 2.95
2.0 ≦ B ≦ 2.95
When less than 1/2 of B is a propionate group 2.6 ≦ A + B ≦ 2.95
1.3 ≦ B ≦ 2.5
More preferably,
When 1/2 or more of B is a propionate group 2.7 ≦ A + B ≦ 2.95
2.4 ≦ B ≦ 2.9
When less than 1/2 of B is a propionate group 2.7 ≦ A + B ≦ 2.95
1.3 ≦ B ≦ 2.0

  The cellulose acylate resin is characterized in that the substitution degree of the acetate group in the acyl group is reduced and the total substitution degree of the propionate group, butyrate group, and pentanoyl group is increased. Thereby, it is easy to lower the melt viscosity and to make the desired viscosity range. This is to increase the free volume between molecules by increasing the number of these groups longer than the acetate group, and to suppress the increase in viscosity due to entanglement. However, if the acyl group is longer than the above, the glass transition temperature (Tg) and elastic modulus are excessively lowered, which is not preferable. For this reason, propionate groups, butyrate groups, and pentanoyl groups larger than acetyl groups are preferred, propionate groups and butyrate groups are more preferred, and propionate groups are more preferred.

  The method for producing the cellulose acylate resin will be described in detail. The raw material cotton and the synthesis method of the cellulose acylate resin are also described in detail on pages 7 to 12 of the Japan Society for Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Institute of Invention). ing.

(Raw material and pretreatment)
As the cellulose raw material, those derived from hardwood pulp, softwood pulp and cotton linter are preferably used. As a cellulose raw material, it is preferable to use a high-purity material having an α-cellulose content of 92 mass% to 99.9 mass%.
When the cellulose raw material is in the form of a film or a lump, it is preferable to pulverize in advance, and it is preferable that the pulverization proceeds until the cellulose form is fluffy.

(Pretreatment (activation))
Prior to acylation, the cellulose raw material is preferably subjected to a treatment (activation) for contact with an activator. As the activator, carboxylic acid or water can be used. However, when water is used, an excess of acid anhydride is added after activation to perform dehydration or to replace water. It is preferable to include a step of washing with an acid or adjusting acylation conditions. The activator may be added by adjusting to any temperature, and the addition method can be selected from spraying, dropping, dipping and the like.

  Preferred carboxylic acids as the activator are carboxylic acids having 2 to 7 carbon atoms (for example, acetic acid, propionic acid, butyric acid, 2-methylpropionic acid, valeric acid, 3-methylbutyric acid, 2-methylbutyric acid, 2,2 -Dimethylpropionic acid (pivalic acid), hexanoic acid, 2-methylvaleric acid, 3-methylvaleric acid, 4-methylvaleric acid, 2,2-dimethylbutyric acid, 2,3-dimethylbutyric acid, 3,3-dimethylbutyric acid , Cyclopentanecarboxylic acid, heptanoic acid, cyclohexanecarboxylic acid, benzoic acid and the like, more preferably acetic acid, propionic acid, or butyric acid, and particularly preferably acetic acid.

  At the time of activation, an acylation catalyst such as sulfuric acid can be further added as necessary. However, when a strong acid such as sulfuric acid is added, depolymerization may be promoted. Therefore, the addition amount is preferably limited to about 0.1% by mass to 10% by mass with respect to cellulose. Two or more kinds of activators may be used in combination, or an acid anhydride of a carboxylic acid having 2 to 7 carbon atoms may be added.

  The addition amount of the activator is preferably 5% by mass or more, more preferably 10% by mass or more, and particularly preferably 30% by mass or more based on cellulose. It is preferable that the amount of the activator is equal to or more than the lower limit value because problems such as a decrease in the degree of activation of cellulose do not occur. The upper limit of the addition amount of the activator is not particularly limited as long as productivity is not lowered, but it is preferably 100 times or less, more preferably 20 times or less, and 10 times or less by mass with respect to cellulose. It is particularly preferred that Activation may be carried out by adding a large excess of activator to cellulose, and then the amount of the activator may be reduced by performing operations such as filtration, air drying, heat drying, distillation under reduced pressure, and solvent substitution.

  The activation time is preferably 20 minutes or more, and the upper limit thereof is not particularly limited as long as it does not affect the productivity, but is preferably 72 hours or less, more preferably 24 hours or less, Especially preferably, it is 12 hours or less. The activation temperature is preferably 0 ° C to 90 ° C, more preferably 15 ° C to 80 ° C, and particularly preferably 20 ° C to 60 ° C. The step of activating cellulose can also be performed under pressure or reduced pressure. Moreover, you may use electromagnetic waves, such as a microwave and infrared rays, as a heating means.

By such activation treatment, the number of foreign matters in the cellulose acylate resin can be 25 / cm ² or less, more preferably 22 / cm ² or less, and still more preferably 20 / cm ² or less. This foreign material is derived from unreacted cellulose in the cellulose acylate. In other words, since the acylating agent does not penetrate into the inside of the cellulose, it is caused by the unreacted cellulose remaining. Foreign matter can be reduced. The foreign matter is derived from the original cellulose being fibrous, and has an elongated needle shape. For this reason, it is preferable to remove from the reaction stage as in the present invention because the filtration cannot pass through the space between the filter media sufficiently.
If such foreign matter is present, non-uniformity occurs in the melt, and residual strain is likely to occur when the melt is cooled between the die and the CD, and a polarizing plate is produced by laminating a cellulose acylate film. In this case, it tends to cause peeling from the foreign matter.

(Acylation)
In the method of synthesizing the cellulose acylate resin, it is preferable to acylate the hydroxyl group of cellulose by adding an acid anhydride of carboxylic acid to cellulose and reacting with Bronsted acid or Lewis acid as a catalyst.
Cellulose mixed acylate can be obtained by mixing two carboxylic acid anhydrides as acylating agents or reacting them by sequential addition; mixed acid anhydrides of two carboxylic acids (for example, acetic acid / propionic acid mixed acid anhydride). A mixed acid anhydride (for example, acetic acid / propionic acid mixed acid anhydride) in a reaction system using an acid anhydride (for example, acetic acid and propionic acid anhydride) of a carboxylic acid and another carboxylic acid as a raw material. ) And reacting with cellulose; a cellulose acylate resin having a substitution degree of less than 3 is once synthesized, and a method of further acylating the remaining hydroxyl group with an acid anhydride or acid halide is used. Can do.

(Acid anhydride)
Preferred examples of the carboxylic acid anhydride include compounds having 2 to 7 carbon atoms as the carboxylic acid. Examples of the acid anhydride include acetic anhydride, propionic anhydride, butyric anhydride, 2-methylpropionic anhydride, valeric anhydride, 3-methylbutyric anhydride, 2-methylbutyric anhydride, 2, 2-dimethylpropionic anhydride (pivalic anhydride), hexanoic anhydride, 2-methylvaleric anhydride, 3-methylvaleric anhydride, 4-methylvaleric anhydride, 2,2-dimethylbutyric anhydride And 2,3-dimethylbutyric anhydride, 3,3-dimethylbutyric anhydride, cyclopentanecarboxylic anhydride, heptanoic anhydride, cyclohexanecarboxylic anhydride, benzoic anhydride, and the like.
The acid anhydride is more preferably an anhydride such as acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, hexanoic anhydride, heptanoic anhydride, and particularly preferably acetic anhydride. , Propionic anhydride, butyric anhydride.
For the purpose of preparing a mixed ester, it is preferable to use these acid anhydrides in combination. The mixing ratio is preferably determined according to the substitution ratio of the target mixed ester. The acid anhydride is usually added in excess equivalent to the cellulose. That is, it is preferable to add 1.2-50 equivalent with respect to the hydroxyl group of a cellulose, it is more preferable to add 1.5-30 equivalent, and it is especially preferable to add 2-10 equivalent.

(catalyst)
It is preferable to use Bronsted acid or Lewis acid as the acylation catalyst used in the production of the cellulose acylate resin. The definitions of Bronsted acid and Lewis acid are described in, for example, “Physical and Chemical Dictionary”, 5th edition (2000). Examples of preferable Bronsted acid include sulfuric acid, perchloric acid, phosphoric acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid and the like. Examples of preferred Lewis acids include zinc chloride, tin chloride, antimony chloride, magnesium chloride and the like.
As the catalyst, sulfuric acid or perchloric acid is more preferable, and sulfuric acid is particularly preferable. The preferable addition amount of a catalyst is 0.1-30 mass% with respect to a cellulose, More preferably, it is 1-15 mass%, Most preferably, it is 3-12 mass%.

(solvent)
In carrying out acylation, a solvent may be added for the purpose of adjusting viscosity, reaction rate, stirring ability, acyl substitution ratio, and the like. As such a solvent, dichloromethane, chloroform, carboxylic acid, acetone, ethyl methyl ketone, toluene, dimethyl sulfoxide, sulfolane and the like can be used, but carboxylic acid is preferable, for example, a carboxylic acid having 2 to 7 carbon atoms. Acids {eg acetic acid, propionic acid, butyric acid, 2-methylpropionic acid, valeric acid, 3-methylbutyric acid, 2-methylbutyric acid, 2,2-dimethylpropionic acid (pivalic acid), hexanoic acid, 2-methylvaleric acid , 3-methylvaleric acid, 4-methylvaleric acid, 2,2-dimethylbutyric acid, 2,3-dimethylbutyric acid, 3,3-dimethylbutyric acid, cyclopentanecarboxylic acid} and the like. More preferable examples include acetic acid, propionic acid, butyric acid and the like. These solvents may be used as a mixture.

(Conditions for acylation)
When acylation is performed, an acid anhydride and a catalyst, and further, if necessary, a solvent may be mixed and then mixed with cellulose, or these may be separately mixed with cellulose. It is preferable to prepare a mixture of an acid anhydride and a catalyst or a mixture of an acid anhydride, a catalyst and a solvent as an acylating agent and then react with cellulose. In order to suppress an increase in temperature in the reaction vessel due to reaction heat during acylation, the acylating agent is preferably cooled in advance. In this case, the cooling temperature is preferably −50 ° C. to 20 ° C., more preferably −35 ° C. to 10 ° C., and particularly preferably −25 ° C. to 5 ° C. The acylating agent may be added in a liquid state or may be frozen and added as a crystal, flake or block solid.

  Further, the acylating agent may be added to the cellulose at once or dividedly. In addition, cellulose may be added to the acylating agent all at once or in divided portions. When the acylating agent is added in portions, the same acylating agent or a plurality of different acylating agents may be used. As a preferred example, 1) a mixture of acid anhydride and solvent is added first, then the catalyst is added, and 2) a mixture of acid anhydride and solvent and a portion of the catalyst is added first, then the catalyst Add the mixture of the rest and solvent 3) Add the mixture of acid anhydride and solvent first, then add the mixture of catalyst and solvent 4) Add the solvent first, acid anhydride and catalyst Or a mixture of an acid anhydride, a catalyst, and a solvent.

Although acylation of cellulose is an exothermic reaction, in the method for producing the cellulose acylate resin, it is preferable that the maximum temperature reached during acylation is 50 ° C. or less. It is preferable that the reaction temperature is lower than this temperature because depolymerization proceeds and there is no inconvenience such as difficulty in obtaining a cellulose acylate resin having a polymerization degree suitable for the use of the present invention. The maximum temperature reached during acylation is preferably 45 ° C. or lower, more preferably 40 ° C. or lower, and particularly preferably 35 ° C. or lower. The reaction temperature may be controlled using a temperature control device or may be controlled by the initial temperature of the acylating agent. The reaction temperature can also be controlled by reducing the pressure of the reaction vessel and the heat of vaporization of the liquid component in the reaction system. Since the exotherm during the acylation is large in the initial stage of the reaction, it is possible to control such as cooling in the initial stage of the reaction and heating thereafter. The end point of acylation can be determined by means such as light transmittance, solution viscosity, temperature change of the reaction system, solubility of the reaction product in an organic solvent, and observation with a polarizing microscope.
The minimum reaction temperature is preferably −50 ° C. or higher, more preferably −30 ° C. or higher, and particularly preferably −20 ° C. or higher. A preferable acylation time is 0.5 to 24 hours, more preferably 1 to 12 hours, and particularly preferably 1.5 to 6 hours. If it is 0.5 hours or less, the reaction may not sufficiently proceed under normal reaction conditions, and if it exceeds 24 hours, it is not preferable for industrial production.

(Reaction terminator)
In the method for producing the cellulose acylate resin used in the present invention, it is preferable to add a reaction terminator after the acylation reaction.
The reaction terminator may be any as long as it decomposes an acid anhydride. Preferred examples include water, alcohol (eg, ethanol, methanol, propanol, isopropyl alcohol, etc.) or a composition containing these. Can be mentioned. Moreover, the reaction terminator may contain a neutralizing agent described later. When adding a reaction terminator, there is a case where a large heat generation exceeding the cooling capacity of the reactor occurs, which may cause a decrease in the degree of polymerization of the cellulose acylate resin, or the cellulose acylate may precipitate in an undesired form. In order to avoid such disadvantages, it is preferable to add a mixture of carboxylic acid such as acetic acid, propionic acid and butyric acid and water rather than directly adding water or alcohol, and acetic acid is particularly preferable as the carboxylic acid. The composition ratio of carboxylic acid and water can be used at any ratio, but the water content is 5% by mass to 80% by mass, further 10% by mass to 60% by mass, and particularly 15% by mass to 50% by mass. It is preferable that it is the range of these.

  The reaction terminator may be added to the acylation reaction vessel or the reactant may be added to the reaction terminator vessel. The reaction terminator is preferably added over 3 minutes to 3 hours. If the addition time of the reaction terminator is 3 minutes or more, the exotherm becomes too large, causing a decrease in the degree of polymerization, insufficient hydrolysis of the acid anhydride, and the stability of the cellulose acylate resin. This is preferable because there is no inconvenience such as reduction. Moreover, it is preferable that the addition time of the reaction terminator is 3 hours or less because problems such as industrial productivity decrease do not occur. The addition time of the reaction terminator is preferably 4 minutes to 2 hours, more preferably 5 minutes to 1 hour, and particularly preferably 10 minutes to 45 minutes. When adding the reaction terminator, the reaction vessel may or may not be cooled, but for the purpose of suppressing depolymerization, it is preferable to cool the reaction vessel to suppress the temperature rise. It is also preferable to cool the reaction terminator.

(Neutralizer)
In order to hydrolyze excess carboxylic anhydride remaining in the system or neutralize part or all of the carboxylic acid and esterification catalyst after the acylation termination step or the acylation termination step, Additives (eg, calcium, magnesium, iron, aluminum or zinc carbonates, acetates, hydroxides or oxides) or solutions thereof may be added. As a solvent for the neutralizing agent, water, alcohol (eg, ethanol, methanol, propanol, isopropyl alcohol, etc.), carboxylic acid (eg, acetic acid, propionic acid, butyric acid, etc.), ketone (eg, acetone, ethyl methyl ketone, etc.), Preferred examples include polar solvents such as dimethyl sulfoxide and mixed solvents thereof.

(Partial hydrolysis)
The cellulose acylate resin thus obtained has a total degree of substitution of nearly 3. However, for the purpose of obtaining a desired degree of substitution, a small amount of catalyst (generally, a remaining acyl such as sulfuric acid) is used. The ester bond is partially hydrolyzed by keeping it at 20 to 90 ° C. for several minutes to several days in the presence of water and a catalyst to reduce the acyl substitution degree of the cellulose acylate resin to a desired level. (So-called aging) is generally performed. Since the cellulose sulfate ester is also hydrolyzed during the partial hydrolysis, the amount of sulfate ester bound to the cellulose can be reduced by adjusting the hydrolysis conditions.
When the desired cellulose acylate is obtained, it is preferable to completely neutralize the catalyst remaining in the system using the neutralizing agent as described above or a solution thereof to stop partial hydrolysis. . By adding a neutralizing agent (for example, magnesium carbonate, magnesium acetate, etc.) that generates a salt that is poorly soluble in the reaction solution, a catalyst (for example, sulfate ester) bound to the solution or cellulose is effectively removed. It is also preferable to remove.

(Filtration)
The reaction mixture (dope) is preferably filtered for the purpose of removing or reducing unreacted substances, hardly soluble salts, and other foreign matters in the cellulose acylate. Filtration may be performed at any step between the completion of acylation and reprecipitation. For the purpose of controlling filtration pressure and handleability, it is also preferable to dilute with an appropriate solvent prior to filtration.

(Reprecipitation)
The cellulose acylate solution thus obtained is mixed in a poor solvent such as water or an aqueous solution of carboxylic acid (for example, acetic acid, propionic acid, etc.), or the poor solvent is mixed in the cellulose acylate solution. As a result, the cellulose acylate resin can be reprecipitated, and the desired cellulose acylate resin can be obtained by washing and stabilizing treatment. Reprecipitation may be carried out continuously or batchwise by a fixed amount. It is also preferable to control the form and molecular weight distribution of the re-precipitated cellulose acylate resin by adjusting the concentration of the cellulose acylate solution and the composition of the poor solvent according to the substitution mode of the cellulose acylate resin or the degree of polymerization.

(Washing)
The produced cellulose acylate resin is preferably washed. Any washing solvent may be used as long as it has low solubility of the cellulose acylate resin and can remove impurities, but water or warm water is usually used as washing water. The temperature of the washing water is preferably 25 ° C to 100 ° C, more preferably 30 ° C to 90 ° C, and particularly preferably 40 ° C to 80 ° C. The washing treatment may be performed in a so-called batch system in which filtration and replacement with a washing liquid are repeated, or may be carried out using a continuous washing apparatus. It is also preferable to reuse the waste liquid generated in the reprecipitation and washing steps as a poor solvent in the reprecipitation step, or to recover and reuse a solvent such as carboxylic acid by means such as distillation.
The progress of washing may be traced by any means, but preferable examples include methods such as hydrogen ion concentration, ion chromatography, electrical conductivity, ICP, elemental analysis, and atomic absorption spectrum.
By such treatment, the catalyst (sulfuric acid, perchloric acid, trifluoroacetic acid, p-toluenesulfonic acid, methanesulfonic acid, zinc chloride, etc.) in the cellulose acylate, neutralizer (for example, calcium, magnesium, iron, Aluminum or zinc carbonates, acetates, hydroxides or oxides), reaction products of neutralizing agents with catalysts, carboxylic acids (eg acetic acid, propionic acid, butyric acid), reactions of neutralizing agents with carboxylic acids Can be removed, which is effective to increase the stability of the cellulose acylate resin.

(Stabilization)
Cellulose acylate resin after washing with hot water treatment is weakly alkaline (for example, carbonates such as sodium, potassium, calcium, magnesium, aluminum, hydrogen carbonate, etc.) in order to further improve the stability or reduce the carboxylic acid odor. It is also preferable to perform the stabilization treatment with an aqueous solution of a salt, hydroxide, oxide or the like).
Further, the amount of residual impurities in the cellulose acylate resin can be controlled by the amount of the cleaning liquid, the cleaning temperature, the time, the stirring method, the configuration of the cleaning container, the composition and concentration of the stabilizer. In the present invention, it is preferable to set the conditions for acylation, partial hydrolysis and washing so that the amount of residual sulfate radical (as the sulfur atom content) is 0 to 500 ppm.

(Dry)
In the present invention, in order to adjust the water content of the cellulose acylate resin to a preferable amount, it is preferable to dry the cellulose acylate resin. The drying method is not particularly limited as long as the desired moisture content can be obtained. However, it is preferable that the drying method be performed efficiently by using means such as heating, air blowing, decompression, and stirring alone or in combination. At this time, the drying temperature is preferably 0 to 200 ° C, more preferably 40 to 180 ° C, and particularly preferably 50 to 160 ° C. The cellulose acylate resin preferably has a moisture content of 2% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.7% by mass or less.

(Form)
The cellulose acylate resin can take various shapes such as particles, powders, fibers, and lumps, but the raw material for film production is preferably particles or powders. For this reason, the cellulose acylate resin after drying may be pulverized or sieved in order to make the particle size uniform and improve the handleability. When the cellulose acylate is in the form of particles, 90% by mass or more of the particles used preferably have a particle size of 0.5 to 5 mm. Moreover, it is preferable that 50 mass% or more of the particle | grains to be used have a particle size of 1-4 mm. The cellulose acylate particles preferably have a shape as close to a sphere as possible. The cellulose acylate particles preferably have an apparent density of 0.5 to 1.3, more preferably 0.7 to 1.2, and particularly preferably 0.8 to 1.15. The method for measuring the apparent density is defined in JIS K7365 (1999).
The cellulose acylate particles preferably have an angle of repose of 10 to 70 °, more preferably 15 to 60 °, and particularly preferably 20 to 50 °.

(Degree of polymerization)
The number average degree of polymerization of the cellulose acylate preferably used in the present invention is 110 to 270, preferably 120 to 260, and more preferably 140 to 250. The number average degree of polymerization is measured by a method using gel permeation chromatography (GPC) described later in the present invention.
When the degree of polymerization is higher than this range, the melt viscosity of the resin becomes high and film formation becomes difficult, and the modulus of elasticity increases and the dimensional change rate and warpage increase. On the other hand, when the degree of polymerization is lower than this range, the dimensional change rate and warpage are small, but the film strength is low, which is not practical.

In the present invention, the weight average polymerization degree / number average polymerization degree by GPC of the cellulose acylate resin is preferably 1.6 to 3.6, more preferably 1.7 to 3.3. It is especially preferable that it is .8 to 3.2.
These cellulose acylate resins may be used alone or in combination of two or more. Moreover, what mixed suitably polymer components other than a cellulose acylate resin may be used. The polymer component to be mixed is preferably one having excellent compatibility with the cellulose ester, and the transmittance when formed into a film is 80% or more, more preferably 90% or more, and further preferably 92% or more.

(Aromatic acylated cellulose acylate)
In the present invention, it is also preferable to use cellulose acylate having a composition satisfying the following formulas (T-1) and (T-2).
Formula (T-1): 2.5 <= A + C <3.0
Formula (T-2): 0.1 ≦ C <2
More preferably, the formula (T-3): 2.6 ≦ A + C <2.95
Formula (T-4): 0.1 ≦ C <1.5
More preferably, the formula (T-3): 2.7 ≦ A + C <2.95
Formula (T-4): 0.1 ≦ C <1.0
It is.
In the formula, A represents the degree of substitution of the acetate group, and C represents a substituted or unsubstituted aromatic acyl group.
Examples of the substituted or unsubstituted aromatic acyl group include groups represented by the following general formula (I).

First, general formula (I) will be described. X is a substituent, and examples of the substituent include a halogen atom, a cyano group, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an acyl group, a carbonamido group, a sulfonamido group, a ureido group, an aralkyl group, and a nitro group. Group, alkoxycarbonyl group, aryloxycarbonyl group, aralkyloxycarbonyl group, carbamoyl group, sulfamoyl group, acyloxy group, alkenyl group, alkynyl group, alkylsulfonyl group, arylsulfonyl group, alkyloxysulfonyl group, aryloxysulfonyl group, alkyl Sulfonyloxy group and aryloxysulfonyl group, —S—R, —NH—CO—OR, —PH—R, —P (—R) ₂ , —PH—O—R, —P (—R) (— O -R), -P (-O-R) ₂ , -PH (= O) -RP (= O) (-R) ₂ , -PH (= O) -O-R, -P (= O) (-R) (-O-R), -P (= O) (-O-R) ₂ , -O-PH (= O) -R, -O- P (═O) (— R) ₂ —O—PH (═O) —O—R, —O—P (═O) (— R) (— O—R), —O—P (═O) (—O—R) ₂ , —NH—PH (═O) —R, —NH—P (═O) (— R) (— O—R), —NH—P (═O) (— O— _{R) 2, -SiH 2 -R,} -SiH (-R) 2, -Si (-R) 3, -O-SiH 2 -R, -O-SiH (-R) 2 and -O-Si (- R) ₃ is included. R is an aliphatic group, an aromatic group or a heterocyclic group. The number of substituents is preferably 1 to 5, more preferably 1 to 4, further preferably 1 to 3, and most preferably 1 or 2. As the substituent, a halogen atom, a cyano group, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an acyl group, a carbonamido group, a sulfonamide group, and a ureido group are preferable, and a halogen atom, a cyano group, an alkyl group, an alkoxy group Group, aryloxy group, acyl group and carbonamido group are more preferred, halogen atom, cyano group, alkyl group, alkoxy group and aryloxy group are more preferred, and halogen atom, alkyl group and alkoxy group are most preferred.

The halogen atom includes a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.
The alkyl group may have a cyclic structure or a branched structure. The number of carbon atoms in the alkyl group is preferably 1-20, more preferably 1-12, still more preferably 1-6, and most preferably 1-4. When the alkyl group has a substituent, the number including the number of carbon atoms of the substituent is preferably the number of carbon atoms (hereinafter, the same applies to other groups). Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, tert-butyl group, hexyl group, cyclohexyl group, octyl group and 2-ethylhexyl group.
The alkoxy group may have a cyclic structure or a branch. The number of carbon atoms in the alkoxy group is preferably 1-20, more preferably 1-12, still more preferably 1-6, and most preferably 1-4. The alkoxy group may be further substituted with another alkoxy group. Examples of the alkoxy group include methoxy group, ethoxy group, 2-methoxyethoxy group, 2-methoxy-2-ethoxyethoxy group, butyloxy group, hexyloxy group and octyloxy group.

The number of carbon atoms of the aryl group is preferably 6-20, and more preferably 6-12. Examples of the aryl group include a phenyl group and a naphthyl group. The aryloxy group preferably has 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms.
Examples of the aryloxy group include a phenoxy group and a naphthoxy group. The number of carbon atoms in the acyl group is preferably 1-20, and more preferably 1-12.
Examples of the acyl group include a formyl group, an acetyl group, and a benzoyl group.
The carbon atom number of the carbonamide group is preferably 1-20, and more preferably 1-12. Examples of the carbonamido group include an acetamide group and a benzamide group. The number of carbon atoms in the sulfonamide group is preferably 1-20, and more preferably 1-12.
Examples of the sulfonamide group include a methanesulfonamide group, a benzenesulfonamide group, and a p-toluenesulfonamide group.
The number of carbon atoms in the ureido group is preferably 1-20, and more preferably 1-12. Examples of ureido groups include (unsubstituted) ureido groups.

The number of carbon atoms in the aralkyl group is preferably 7-20, and more preferably 7-12. Examples of the aralkyl group include a benzyl group, a phenethyl group, and a naphthylmethyl group. The number of carbon atoms in the alkoxycarbonyl group is preferably 1-20, and more preferably 2-12.
Examples of the alkoxycarbonyl group include a methoxycarbonyl group. The number of carbon atoms of the aryloxycarbonyl group is preferably 7-20, and more preferably 7-12. Examples of the aryloxycarbonyl group include a phenoxycarbonyl group. The number of carbon atoms in the aralkyloxycarbonyl group is preferably 8-20, and more preferably 8-12. Examples of the aralkyloxycarbonyl group include a benzyloxycarbonyl group. The number of carbon atoms of the carbamoyl group is preferably 1-20, and more preferably 1-12. Examples of the carbamoyl group include a (unsubstituted) carbamoyl group and an N-methylcarbamoyl group. The number of carbon atoms in the sulfamoyl group is preferably 20 or less, and more preferably 12 or less. Examples of the sulfamoyl group include a (unsubstituted) sulfamoyl group and an N-methylsulfamoyl group.
The number of carbon atoms in the acyloxy group is preferably 1-20, and more preferably 2-12. Examples of the acyloxy group include an acetoxy group and a benzoyloxy group.

The alkenyl group has preferably 2 to 20 carbon atoms, and more preferably 2 to 12 carbon atoms. Examples of the alkenyl group include a vinyl group, an allyl group, and an isopropenyl group. The alkynyl group preferably has 2 to 20 carbon atoms, and more preferably 2 to 12 carbon atoms.
Examples of the alkynyl group include a thienyl group. The number of carbon atoms in the alkylsulfonyl group is preferably 1-20, and more preferably 1-12. The number of carbon atoms of the arylsulfonyl group is preferably 6-20, and more preferably 6-12.
The number of carbon atoms in the alkyloxysulfonyl group is preferably 1-20, and more preferably 1-12.
The number of carbon atoms of the aryloxysulfonyl group is preferably 6-20, and more preferably 6-12.
The number of carbon atoms of the alkylsulfonyloxy group is preferably 1-20, and more preferably 1-12. The number of carbon atoms of the aryloxysulfonyl group is preferably 6-20, and more preferably 6-12.

  Such compounds are obtained by substituting an aromatic acyl group for the hydroxyl group of cellulose and generally use symmetric acid anhydrides and mixed acid anhydrides derived from aromatic carboxylic acid claloids or aromatic carboxylic acids. Methods and the like. Particularly preferred is a method using an acid anhydride derived from an aromatic carboxylic acid (Journal of Applied Polymer Science, Vol. 29, 3981-3990 (1984)). As a method for producing the cellulose mixed acid ester compound of the present invention as the above method, (1) once the cellulose fatty acid monoester or diester is produced, the remaining hydroxyl group is an aromatic acyl represented by the above general formula (I) And (2) a method of reacting a mixed acid anhydride of an aliphatic carboxylic acid and an aromatic carboxylic acid directly with cellulose. In the method (1), a known method can be adopted as the method for producing cellulose fatty acid ester or diester, and the subsequent reaction for further introducing an aromatic acyl group is appropriately determined depending on the kind of the aromatic acyl group. The reaction temperature is preferably 0 to 100 ° C., more preferably 20 to 50 ° C., and the reaction time is preferably 30 minutes or more, more preferably 30 to 300 minutes. In the method using the mixed acid anhydride (2), the reaction conditions can be appropriately determined depending on the type of the mixed acid anhydride, but the reaction temperature is preferably 0 to 100 ° C., more preferably 20 to 50. C. and the reaction time are preferably 30 to 300 minutes, more preferably 60 to 200 minutes. In any of the above reactions, the reaction may be carried out either without a solvent or in a solvent, but is preferably carried out using a solvent. As the solvent, dichloromethane, chloroform, dioxane and the like can be used.

Specific examples of the aromatic acyl group represented by the general formula (I) are shown below, but the present invention is not limited thereto.

  Among these substituents, the substituents of 1 to 9, 18 to 19, and 27 to 28 are preferable, more preferably 1 to 3 substituents, and most preferably 1 substituent.

[Additive]
(Plasticizer)
Furthermore, in the present invention, a plasticizer can be added to the cellulose acylate resin. When a plasticizer is added to the cellulose acylate resin, stretching strain is easily reduced. Examples of the plasticizer include alkyl phthalyl alkyl glycolates, phosphoric acid esters and carboxylic acid esters.
Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl glycolate Ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl glycolate, Butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalyl ester Le glycolate, and the like.
Examples of phosphate esters include triphenyl phosphate, tricresyl phosphate, phenyl diphenyl phosphate, and the like. Furthermore, it is preferable to use the phosphate ester plasticizer described in claims 3 to 7 of JP-T-6-501040.
Examples of carboxylic acid esters include phthalic acid esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate and diethyl hexyl phthalate, and citrate esters such as acetyl trimethyl citrate, acetyl triethyl citrate and acetyl tributyl citrate. And adipic acid esters such as dimethyl adipate, dibutyl adipate, diisobutyl adipate, bis (2-ethylhexyl) adipate, diisodecyl adipate, and bis (butyl diglycol adipate). In addition, butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, triacetin and the like are preferably used alone or in combination.
These plasticizers are preferably 0% by mass to 20% by mass, more preferably 1% by mass to 20% by mass, and still more preferably 2% by mass to 15% by mass with respect to the cellulose acylate film. These plasticizers may be used in combination of two or more if necessary.

It is also preferable to add a polyhydric alcohol plasticizer in addition to these plasticizers. The polyhydric alcohol plasticizer that can be specifically used in the present invention has good compatibility with cellulose fatty acid esters, and glycerin ester compounds such as glycerin esters and diglycerin esters in which the thermoplastic effect is remarkable, Examples thereof include polyalkylene glycols such as polyethylene glycol and polypropylene glycol, and compounds in which an acyl group is bonded to a hydroxyl group of polyalkylene glycol.
Specific glycerin esters include glycerin diacetate stearate, glycerin diacetate palmitate, glycerin diacetate myristate, glycerin diacetate laurate, glycerin diacetate caprate, glycerin diacetate nonanate, glycerin diacetate octanoate, Glycerin diacetate heptanoate, glycerol diacetate hexanoate, glycerol diacetate pentanoate, glycerol diacetate oleate, glycerol acetate dicaprate, glycerol acetate dioctanoate, glycerol acetate dioctanoate, glycerol acetate diheptanoate , Glycerol acetate dicaproate, glycerol acetate divalerate, glycerol acetate dibu Glycerol dipropionate caprate, glycerol dipropionate laurate, glycerol dipropionate myristate, glycerol dipropionate palmitate, glycerol dipropionate stearate, glycerol dipropionate oleate, glycerol tributyrate, glycerol tri Examples include but are not limited to pentanoate, glycerin monopalmitate, glycerin monostearate, glycerin distearate, glycerin propionate laurate, glycerin oleate propionate, and these are used alone or in combination. be able to.
Among them, glycerol diacetate caprylate, glycerol diacetate pelargonate, glycerol diacetate caprate, glycerol diacetate laurate, glycerol diacetate myristate, glycerol diacetate palmitate, glycerol diacetate stearate, glycerol diacetate oleate preferable.

Specific examples of diglycerin esters include diglycerin tetraacetate, diglycerin tetrapropionate, diglycerin tetrabutyrate, diglycerin tetravalerate, diglycerin tetrahexanoate, diglycerin tetraheptanoate, diglyceride. Glycerin tetracaprylate, diglycerin tetrapelargonate, diglycerin tetracaprate, diglycerin tetralaurate, diglycerin tetramyristate, diglycerin tetrapalmitate, diglycerin triacetate propionate, diglycerin triacetate butyrate, diglycerin Triacetate valerate, diglycerin triacetate hexanoate, diglycerin triacetate heptanoate, diglycerin triacetate caprylate, Glycerin triacetate pelargonate, diglycerol triacetate caprate, diglycerol triacetate laurate, diglycerol triacetate myristate, diglycerol triacetate palmitate, diglycerol triacetate stearate, diglycerol triacetate oleate, diglycerol diacetate dipropionate, diglycerol Diacetate dibutyrate, diglycerin diacetate divalerate, diglycerin diacetate dihexanoate, diglycerin diacetate diheptanoate, diglycerin diacetate dicaprylate, diglycerin diacetate dipelargonate, diglycerin di Acetate dicaprate, diglycerin diacetate dilaurate, diglycerin diacetate dimisti Diglycerin diacetate dipalmitate, diglyceryl diacetate distearate, diglycerin diacetate dioleate, diglyceryl acetate tripropionate, diglyceryl acetate tributyrate, diglyceryl acetate trivalerate, diglyceryl acetate tri Hexanoate, diglycerol acetate triheptanoate, diglycerol acetate tricaprylate, diglycerol acetate tripelargonate, diglycerol acetate tricaprate, diglycerol acetate trilaurate, diglycerol acetate trimyristate, diglycerol acetate tri Palmitate, Diglycerol acetate tristearate, Diglycerol acetate trioleate, Diglycerol laurate, Jig Examples include, but are not limited to, mixed acid esters of diglycerin such as glycerin stearate, diglycerin caprylate, diglycerin myristate, and diglycerin oleate, and these can be used alone or in combination.
Among these, diglycerin tetraacetate, diglycerin tetrapropionate, diglycerin tetrabutyrate, diglycerin tetracaprylate, and diglycerin tetralaurate are preferable.

  Specific examples of the polyalkylene glycol include polyethylene glycol and polypropylene glycol having an average molecular weight of 200 to 1000, but are not limited thereto, and these can be used alone or in combination.

  Specific examples of the compound in which an acyl group is bonded to the hydroxyl group of polyalkylene glycol include polyoxyethylene acetate, polyoxyethylene propionate, polyoxyethylene butyrate, polyoxyethylene valerate, polyoxyethylene caproate, Polyoxyethylene heptanoate, polyoxyethylene octanoate, polyoxyethylene nonanate, polyoxyethylene caprate, polyoxyethylene laurate, polyoxyethylene myristate, polyoxyethylene palmitate, polyoxyethylene stearate , Polyoxyethylene oleate, polyoxyethylene linoleate, polyoxypropylene acetate, polyoxypropylene propionate, polyoxypropylene butyrate, polyoxypropylene Valerate, polyoxypropylene caproate, polyoxypropylene heptanoate, polyoxypropylene octanoate, polyoxypropylene nonanate, polyoxypropylene caprate, polyoxypropylene laurate, polyoxypropylene myristate, polyoxy Examples thereof include propylene palmitate, polyoxypropylene stearate, polyoxypropylene oleate, and polyoxypropylene linoleate, but are not limited thereto, and these can be used alone or in combination.

(Stabilizer)
In the present invention, it is preferable to use either or both of a phosphite compound and a phosphite compound as a stabilizer. The blending amount of these stabilizers is preferably 0.005 to 0.5% by mass, more preferably 0.01 to 0.4% by mass, and still more preferably 0.02 to 0.3% by mass. .

(I) Phosphite stabilizer Specific phosphite stabilizers are not particularly limited, but phosphite stabilizers represented by the following general formulas (2) to (4) are preferable.

(Here, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ′ ¹ , R ′ ² , R ′ ³ ... R ′ ^p , R ′ ^{p + 1}
Is selected from the group consisting of hydrogen or an alkyl, aryl, alkoxyalkyl, aryloxyalkyl, alkoxyaryl, arylalkyl, alkylaryl, polyaryloxyalkyl, polyalkoxyalkyl and polyalkoxyaryl group having 4 to 23 carbon atoms Indicates a group. However, not all of the same formulas in the general formulas (2), (3), and (4) become hydrogen. X in the phosphite stabilizer represented by the general formula (3) is an aliphatic chain, an aliphatic chain having an aromatic nucleus in a side chain, an aliphatic chain having an aromatic nucleus in the chain, and the chain. Indicates a group selected from the group consisting of a chain containing two or more non-continuous oxygen atoms. K and q are integers of 1 or more, and p is an integer of 3 or more. )

  The numbers of k and q in these phosphite stabilizers are preferably 1 to 10. By setting the number of k and q to 1 or more, volatility at the time of heating is reduced, and setting to 10 or less is preferable because compatibility with cellulose acetate propionate is improved. The value of p is preferably 3-10. By setting it to 3 or more, volatility at the time of heating becomes small, and setting it to 10 or less is preferable because compatibility with cellulose acetate propionate is improved.

  As a specific example of the phosphite stabilizer represented by the following general formula (2), those represented by the following general formulas (5) to (8) are preferable.

  Moreover, as a specific example of the phosphite stabilizer represented by the following general formula (3), those represented by the following general formulas (9) to (11) are preferable.

(ii) Phosphite ester stabilizer Examples of the phosphite ester stabilizer include cyclic neopentanetetraylbis (octadecyl) phosphite, cyclic neopentanetetraylbis (2,4-di-tert-). Butylphenyl) phosphite, cyclic neopentanetetraylbis (2,6-di-tert-butyl-4-methylphenyl) phosphite, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl Examples thereof include phosphite and tris (2,4-di-tert-butylphenyl) phosphite.

(iii) Other stabilizers In addition, weak organic acids, thioether compounds, epoxy compounds and the like may be added as stabilizers.
The weak organic acid is not particularly limited as long as it has a pKa of 1 or more, does not interfere with the action of the present invention, and has coloration prevention properties and physical property deterioration prevention properties. Examples thereof include tartaric acid, citric acid, malic acid, fumaric acid, oxalic acid, succinic acid, maleic acid and the like. These may be used alone or in combination of two or more.
Examples of the thioether compound include dilauryl thiodipropionate, ditridecyl thiodipropionate, dimyristyl thiodipropionate, distearyl thiodipropionate, and palmityl stearyl thiodipropionate. It may be used in combination, or two or more may be used in combination.
Examples of the epoxy compound include those derived from epichlorohydrin and bisphenol A, such as derivatives from epichlorohydrin and glycerin, vinylcyclohexene dioxide, and 3,4-epoxy-6-methylcyclohexylmethyl-3. Cyclic ones such as 1,4-epoxy-6-methylcyclohexanecarboxylate can also be used. Epoxidized soybean oil, epoxidized castor oil, long chain α-olefin oxides, and the like can also be used. These may be used alone or in combination of two or more.

(Matting agent)
Further, it is preferable to add fine particles as a matting agent to the cellulose acylate resin. The fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and Mention may be made of calcium phosphate.
These fine particles usually form secondary particles having an average particle size of 0.1 to 3.0 μm, and these fine particles exist in the film as aggregates of primary particles, and 0.1 to 0.1 μm on the film surface. An unevenness of 3.0 μm is formed. The secondary average particle size is preferably 0.2 μm to 1.5 μm, more preferably 0.4 μm to 1.2 μm, and most preferably 0.6 μm to 1.1 μm. For the primary and secondary particle sizes, the particles in the film were observed with a scanning electron microscope, and the diameter of a circle circumscribing the particles was defined as the particle size. In addition, 200 particles were observed at different locations, and the average value was taken as the average particle size.
The amount of the fine particles is preferably 1 ppm to 5000 ppm, more preferably 5 ppm to 1000 ppm, and still more preferably 10 ppm to 500 ppm by mass ratio with respect to the cellulose acylate resin.
Fine particles containing silicon are preferable because they can reduce turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / liter or more, and more preferably 100 to 200 g / liter or more. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

As fine particles of silicon dioxide, for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.) can be used. Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.), and these can be used.
Among the above-mentioned fine particles, Aerosil 200V and Aerosil R972V are silicon dioxide fine particles having a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more, and keep the turbidity of the optical film low. However, since the effect of reducing the friction coefficient is great, it is particularly preferable.

(Other additives)
In addition, an infrared absorbent, an ultraviolet absorbent optical modifier, a surfactant, an odor trapping agent (such as amine), and the like can be added to the cellulose acylate resin. These details are disclosed in the Invention Association Public Technique No. 2001-1745 (issued March 15, 2001, Invention Association), p. Materials described in detail in 17-22 are preferably used.
As the infrared absorbing dye, for example, those disclosed in JP-A No. 2001-194522 can be used, and as the ultraviolet absorber, for example, those described in JP-A No. 2001-151901 can be used. The infrared absorber and the ultraviolet absorber are each preferably contained in an amount of 0.001 to 5 mass% with respect to the cellulose acylate resin.

  Examples of the optical adjusting agent include retardation adjusting agents, for example, those described in JP-A Nos. 2001-166144, 2003-344655, 2003-248117, and 2003-66230. Accordingly, in-plane retardation (Re) and thickness direction retardation (Rth) can be controlled. A preferable addition amount is 0 to 10% by mass, more preferably 0 to 8% by mass, and further preferably 0 to 6% by mass.

<Saturated norbornene resin>
In the present invention, it is also preferable to use a saturated norbornene resin as the thermoplastic resin of the thermoplastic film. As the saturated norbornene resin, any of the following saturated norbornene resin-A and saturated norbornene resin-B can be preferably used.

(Saturated norbornene resin-A)
As the saturated norbornene resin-A used in the present invention, for example, (1) a ring-opening (co) polymer of a norbornene monomer was modified with a polymer such as maleic acid addition or cyclopentadiene addition as necessary. Later, hydrogenated resins, (2) resins obtained by addition polymerization of norbornene monomers, and (3) resins obtained by addition copolymerization of norbornene monomers and olefin monomers such as ethylene and α-olefin, etc. be able to. The polymerization method and the hydrogenation method can be performed by conventional methods.

  Examples of the norbornene-based monomer include norbornene and alkyl and / or alkylidene substituted products thereof such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, and 5-butyl. 2-Norbornene, 5-ethylidene-2-norbornene, and the like, polar substituents such as halogens thereof; dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc .; dimethanooctahydronaphthalene, its alkyl and / or alkylidene Substituents and polar group substituents such as halogen such as 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6- Ethyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-oct Hydronaphthalene, 6-ethylidene-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethano -1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a -Octahydronaphthalene, 6-pyridyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4: 5 8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, etc .; adducts of cyclopentadiene and tetrahydroindene, etc .; 3-pentamers of cyclopentadiene, such as 4,9 : 5,8-dimethano-3a, 4,4a, , 8,8a, 9,9a-octahydro-1H-benzoindene, 4,11: 5,10: 6,9-trimethano-3a, 4,4a, 5,5a, 6,9,9a, 10,10a, 11,11a-dodecahydro-1H-cyclopentanthracene; and the like.

(Saturated norbornene resin-B)
Moreover, as saturated norbornene resin-B, what is represented by the following general formula (1)-(4) can be mentioned, Among these, what is represented by the following general formula (1) is especially preferable.

[In General Formulas (1) to (4), A, B, C and D represent a hydrogen atom or a monovalent organic group, and at least one of them represents a polar group. ]

The weight average molecular weight of these saturated norbornene resins is usually preferably 5,000 to 1,000,000, more preferably 8,000 to 200,000.
Examples of the saturated norbornene resin include, for example, JP-A-60-168708, JP-A-62-252406, JP-A-62-2252407, JP-A-2-133413, JP-A-63-3. Examples thereof include resins described in JP-A No. 145324, JP-A-63-264626, JP-A-1-240517, JP-B-57-8815, and the like.
Among these resins, a hydrogenated polymer obtained by hydrogenating a ring-opening polymer of a norbornene monomer is particularly preferable.
The glass transition temperature (Tg) of these saturated norbornene resins is preferably 120 ° C. or higher, more preferably 140 ° C. or higher, and the saturated water absorption is preferably 1% by mass or lower, more preferably 0.8%. 8 mass% or less. The glass transition temperature (Tg) and saturated water absorption of the saturated norbornene resins represented by the general formulas (1) to (4) can be controlled by selecting the type of the substituents A, B, C, and D. .

  As the saturated norbornene resin, at least one tetracyclododecene derivative represented by the following general formula (5) alone or an unsaturated cyclic compound that can be copolymerized with the tetracyclododecene derivative A hydrogenated polymer obtained by hydrogenating a polymer obtained by metathesis polymerization may be used.

（式中、Ａ、Ｂ、ＣおよびＤは、水素原子または１価の有機基を示し、これらのうち少なくとも１つは極性基である。）

(In the formula, A, B, C and D represent a hydrogen atom or a monovalent organic group, and at least one of them is a polar group.)

In the tetracyclododecene derivative represented by the general formula (5), when at least one of A, B, C and D is a polar group, the polarized light has excellent adhesion to other materials, heat resistance, etc. A film can be obtained. Further, the polar group is a group represented by — (CH ₂ ) _n COOR (where R is a hydrocarbon group having 1 to 20 carbon atoms, and n is an integer of 0 to 10). The resulting hydrogenated polymer (polarizing film substrate) is preferred because it has a high glass transition temperature. In particular, the polar substituent represented by — (CH ₂ ) _n COOR is preferably contained in one molecule of the tetracyclododecene derivative of the general formula (5) from the viewpoint of reducing the water absorption rate. In the polar substituent, it is preferable in that the hygroscopicity of the obtained hydrogenated polymer decreases as the number of carbon atoms of the hydrocarbon group represented by R increases, but the balance with the glass transition temperature of the obtained hydrogenated polymer is reduced. From this point, the hydrocarbon group is preferably a chain alkyl group having 1 to 4 carbon atoms or a (poly) cyclic alkyl group having 5 or more carbon atoms, and particularly preferably a methyl group, an ethyl group, or a cyclohexyl group. preferable.

Furthermore, the tetracyclododecene derivative of the general formula (5) in which a hydrocarbon group having 1 to 10 carbon atoms is bonded as a substituent to a carbon atom to which a group represented by — (CH ₂ ) _n COOR is bonded, This is preferable because the resulting hydrogenated polymer has low hygroscopicity. In particular, the tetracyclododecene derivative of the general formula (5) in which the substituent is a methyl group or an ethyl group is preferable in terms of easy synthesis. Specifically, 8-methyl-8-methoxycarbonyltetracyclo [4,4,0,12.5,17.10] dodec-3-ene is preferable. These tetracyclododecene derivatives and mixtures of unsaturated cyclic compounds copolymerizable therewith are described, for example, in JP-A-4-77520, page 4, upper right column, line 12 to page 6, lower right column, line 6. Metathesis polymerization and hydrogenation can be carried out by the prepared method.

These norbornene resins preferably have an intrinsic viscosity (ηinh) measured at 30 ° C. in chloroform of 0.1 to 1.5 dl / g, more preferably 0.4 to 1.2 dl / g. It is. Moreover, as a hydrogenation rate of a hydrogenated polymer, the value measured by 60 MHz and < ¹ > H-NMR shall be 50% or more, Preferably it is 90% or more, More preferably, it is 98% or more. The higher the hydrogenation rate, the more the saturated norbornene film obtained has better stability to heat and light. The gel content contained in the hydrogenated polymer is preferably 5% by mass or less, and more preferably 1% by mass or less.

  Examples of the saturated norbornene resin include known antioxidants such as 2,6-di-tert-butyl-4-methylphenol, 2,2′-dioxy-3,3′-di-tert-butyl-5, 5′-dimethylphenylmethane, tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, 1,1,3-tris (2-methyl-4-hydroxy-5) -Tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, stearyl-β- (3,5- Di-tert-butyl-4-hydroxyphenyl) propionate, 2,2′-dioxy-3,3′-di-tert-butyl-5,5′-diethylphenylmethane 3,9-bis [1,1-dimethyl-2- [β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl], 2,4,8,10-tetraoxspiro [5,5] undecane, tris (2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetra Irbis (2,6-di-tert-butyl-4-methylphenyl) phosphite, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite; UV absorber, eg 2,4 -It can be stabilized by adding dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, etc. Kill. Further, additives such as a lubricant can be added for the purpose of improving processability.

The addition amount of these antioxidants is 0.1-3 mass parts normally with respect to 100 mass parts of saturated norbornene-type resin, Preferably it is 0.2-2 mass parts.
Furthermore, you may add various additives, such as anti-aging agents, such as a phenol type and phosphorus type, an antistatic agent, an ultraviolet absorber, and the above-mentioned easy-to-slip agent, to a saturated norbornene-type resin. In particular, since the liquid crystal is usually deteriorated by ultraviolet rays, it is preferable to add an ultraviolet absorber when other protective measures such as laminating an ultraviolet protective filter are not taken. As the UV absorber, a benzophenone UV absorber, a benzotriazole UV absorber, an acrylonitrile UV absorber, or the like can be used. Among them, a benzophenone UV absorber is preferable, and the addition amount is usually 10 ˜100,000 ppm, preferably 100 to 10,000 ppm. Moreover, when producing a sheet | seat by the solution casting method, in order to make surface roughness small, addition of a leveling agent is preferable. As the leveling agent, for example, a coating leveling agent such as a fluorine-based nonionic surfactant, a special acrylic resin leveling agent, or a silicone leveling agent can be used, and among them, those having good compatibility with a solvent are preferable. The addition amount is usually 5 to 50,000 ppm, preferably 10 to 20,000 ppm.

《Filming》
In the present invention, the residual solvent is preferably 0.01% by mass or less, more preferably 0% by mass. Residual solvent tends to remain locally, and non-uniformity within the film surface tends to occur. Since such a residual solvent is easily generated by solution casting, the thermoplastic film of the present invention is preferably formed by melt casting.

(Melting film forming process)
The method for producing a thermoplastic film of the present invention includes a melt film-forming step of melting and forming a thermoplastic resin in a sheet form on a casting drum from a die as described above.
In the method for producing a thermoplastic film of the present invention, while the molten resin temperature of the sheet-like thermoplastic resin is cooled from Tg + 40 ° C. to Tg, the degree of stretching in the film forming direction is 1% to 25%. A thermoplastic resin is stretched. If the degree of stretching is less than 1%, it is difficult to form a melt substantially unstretched. Further, if the degree of stretching exceeds 25%, the occurrence of residual strain cannot be suppressed. The stretching direction here is the melt transport direction, and the molten resin is stretched in the downstream direction of transport.

(I) Pelletization The (transparent) thermoplastic resin and additive are preferably mixed and pelletized prior to melt film formation.
It is preferable to dry the thermoplastic resin and additives in advance for pelletization, but this can be substituted by using a vented extruder. In the case of drying, a method of heating at 90 ° C. for 8 hours or more in a heating furnace can be used as a drying method, but this is not restrictive. Pelletization can be made by melting the thermoplastic resin and additives at 150 ° C. to 250 ° C. using a twin-screw kneading extruder and then extruding them into noodles and solidifying and cutting in water. Alternatively, pelletization may be performed by an underwater cutting method or the like that cuts while being directly extruded from a die after being melted by an extruder.
Any known single-screw extruder, non-meshing counter-rotating twin-screw extruder, meshing-type counter-rotating twin-screw extruder, meshing co-direction as long as the melter kneading is sufficient A rotary twin screw extruder or the like can be used.
The preferred size is the cross-sectional area of 1 mm ² to 300 mm ² of the pellets, is 1mm~30mm is Preferably length, more preferably the cross-sectional area of 2 mm ² 100 mm ^2, the length is 1.5Mm～10mm.

Moreover, when pelletizing, the said additive can also be injected | thrown-in from the raw material input port and vent port in the middle of an extruder.
The number of revolutions of the extruder is preferably 10 rpm to 1000 rpm, more preferably 20 rpm to 700 rpm, and even more preferably 30 rpm to 500 rpm. Accordingly, when the rotational speed is slow, the residence time becomes long, which is not preferable because the molecular weight is lowered due to thermal deterioration or the yellowishness is easily deteriorated. On the other hand, if the rotational speed is too high, molecules are likely to be cut by shearing, which leads to problems such as a decrease in molecular weight and an increase in the generation of cross-linked gel.
The extrusion residence time in pelletization is 10 seconds or more and within 30 minutes, more preferably 15 seconds to 10 minutes, and further preferably 30 seconds to 3 minutes. If sufficient melting is possible, a shorter residence time is preferable in terms of suppressing resin deterioration and yellowing.

(ii) Drying It is preferable to reduce moisture in the pellets prior to melt film formation. The drying method is often dried using a dehumidifying air dryer, but is not particularly limited as long as the desired water content can be obtained (heating, blowing, decompression, stirring, etc. alone or in combination) It is preferable to use it efficiently, and more preferably, the drying hopper is preferably a heat insulating structure). The drying temperature is preferably 0 to 200 ° C, more preferably 40 to 180 ° C, and particularly preferably 60 to 150 ° C. When the drying temperature is too low, not only does drying take time, but the moisture content does not fall below the target value, which is not preferable. On the other hand, if the drying temperature is too high, the resin sticks and is not preferable. The amount of drying air used is preferably 20 to 400 m ³ / time, more preferably 50 to 300 m ³ / hour, and particularly preferably 100 to 250 m ³ / hour. If the amount of drying air is small, the drying efficiency is unfavorable. On the other hand, even if the air volume is increased, if the amount is more than a certain amount, further improvement of the drying effect is small and not economical. The dew point of air is preferably 0 to -60 ° C, more preferably -10 to -50 ° C, and particularly preferably -20 to -40 ° C. The drying time is required to be at least 15 minutes, more preferably 1 hour or more, and particularly preferably 2 hours or more. On the other hand, even if the drying time exceeds 50 hours, the effect of further reducing the moisture content is small, and there is a concern about thermal degradation of the resin, so it is not preferable to unnecessarily increase the drying time. The thermoplastic resin of the present invention preferably has a moisture content of 1.0% by mass or less, more preferably 0.1% by mass or less, and particularly preferably 0.01% by mass or less.

(iii) Melt extrusion The above-described thermoplastic resin is supplied into the cylinder through the supply port of the extruder. The cylinder was melt kneaded and compressed in order from the supply port side, a supply part (region A) for quantitatively transporting the thermoplastic resin supplied from the supply port, and a compression unit (region B) for melt kneading and compressing the thermoplastic resin. It is comprised with the measurement part (area | region C) which measures a thermoplastic resin. The resin is preferably dried in order to reduce the water content by the above-mentioned method. However, in order to prevent oxidation of the molten resin by residual oxygen, the inside of the extruder is in an inert (nitrogen or the like) air flow or with a vent. More preferably, it is carried out while evacuating using an extruder. The screw compression ratio of the extruder is set to 2.5 to 4.5, and L / D is set to 20 to 70. Here, the screw compression ratio is expressed by the volume ratio between the supply unit A and the metering unit C, that is, the volume per unit length of the supply unit A ÷ the volume per unit length of the metering unit C. It is calculated using the outer diameter d1 of the shaft, the outer diameter d2 of the screw shaft of the measuring part C, the groove part diameter a1 of the supply part A, and the groove part diameter a2 of the measuring part C. L / D is the ratio of the cylinder length to the cylinder inner diameter. Moreover, extrusion temperature is set to 190-240 degreeC. When the temperature in the extruder exceeds 230 ° C., a cooler may be provided between the extruder and the die.

  If the screw compression ratio is less than 2.5 and is too small, it will not be sufficiently melt-kneaded and undissolved parts will occur, undissolved foreign matter will easily remain in the manufactured thermoplastic film, and bubbles will be mixed. It becomes easy. As a result, the strength of the thermoplastic film is lowered, or when the film is stretched, it becomes easy to break and the orientation cannot be sufficiently increased. On the other hand, if the screw compression ratio exceeds 4.5, the shear stress is excessively applied and the resin is easily deteriorated by heat generation, so that a yellowish color is likely to appear in the manufactured thermoplastic film. On the other hand, when too much shear stress is applied, the molecules are cut, the molecular weight is lowered, and the mechanical strength of the film is lowered. Therefore, the screw compression ratio is preferably in the range of 2.5 to 4.5, more preferably 2. In order to make the thermoplastic film after production hardly yellowish and the film strength is strong and the film is not easily stretched and broken. It is 8 to 4.2, particularly preferably in the range of 3.0 to 4.0.

On the other hand, if L / D is less than 20 and is too small, melting and kneading are insufficient, and undissolved foreign matter is likely to be generated in the manufactured thermoplastic film as in the case where the compression ratio is small. On the other hand, if L / D exceeds 70 and is too large, the residence time of the thermoplastic resin in the extruder becomes too long, and the resin tends to be deteriorated. In addition, when the residence time is long, the molecules are cut or the molecular weight is lowered, so that the mechanical strength of the thermoplastic film is lowered. Therefore, L / D is preferably in the range of 20 to 70, more preferably in the range of 22 to 65, in order to make the thermoplastic film after production hardly yellowish and the film strength is strong and further difficult to stretch and break. Especially preferably, it is the range of 24-50.
The extrusion temperature is preferably in the above temperature range. The thermoplastic film thus obtained has a characteristic value with a haze of 2.0% or less and a yellow index (YI value) of 10 or less.
Here, the haze is an index indicating whether the extrusion temperature is too low, in other words, an index for knowing the amount of undissolved foreign matter remaining in the manufactured thermoplastic film. If the haze exceeds 2.0%, It becomes easy to generate | occur | produce the intensity | strength fall of a thermoplastic film, and the fracture | rupture at the time of extending | stretching. The yellow index (YI value) is an index for knowing whether the extrusion temperature is too high. If the yellow index (YI value) is 10 or less, there is no problem in terms of yellowness.

In general, single-screw extruders with relatively low equipment costs are often used as the types of extruders, and there are screw types such as full flight, madok, and dalmage, but cellulose acid with relatively poor thermal stability. The rate resin is preferably a full flight type. In addition, although the equipment cost is effective, it is possible to use a twin-screw extruder that can be extruded while devolatilizing unnecessary volatile components by providing a vent port in the middle by changing the screw segment. There are two types of shaft extruders, the same direction and different directions, which can be used. However, the type of the same direction rotation is preferred because it is less likely to cause a stagnant portion. The twin-screw extruder is effective in equipment, but has high kneadability and high resin supply performance, so that it can be extruded at low temperatures, and is suitable for film formation of cellulose acetate resin that is easily thermally decomposed. By appropriately arranging the vent opening, it is possible to use the cellulose acylate pellets and powder in an undried state as they are. In addition, film smears produced during film formation can be reused as they are without drying.
In addition, although the diameter of a preferable screw changes with the target extrusion amount per unit time, it is 10 mm-300 mm, More preferably, it is 20 mm-250 mm, More preferably, it is 30 mm-150 mm.

(iv) Filtration It is preferable to perform a so-called breaker plate type filtration in which a filter medium is provided at the outlet of the extruder to filter foreign matter in the resin and avoid damage to the gear pump due to foreign matter. In order to filter foreign matter with higher accuracy, it is preferable to provide a filtration device incorporating a so-called leaf type disk filter after passing through the gear pump. Filtration can be performed by providing one filtration section, or multistage filtration performed by providing a plurality of places. Although the filtration accuracy of the filter medium is preferably higher, the filtration accuracy is preferably 15 μm to 3 μmm, more preferably 10 μm to 3 μm, from the viewpoint of the pressure resistance of the filter medium and the increase in the filtration pressure due to clogging of the filter medium. In particular, when using a leaf-type disk filter device that finally filters foreign matter, it is preferable to use a filter medium with high filtration accuracy in terms of quality, and it is adjusted by the number of loaded sheets to ensure the suitability of pressure resistance and filter life. Is possible. The type of filter medium is preferably a steel material because it is used under high temperature and high pressure. Among steel materials, stainless steel, steel, etc. are particularly preferable, and stainless steel is particularly preferable in terms of corrosion. . As a configuration of the filter medium, for example, a sintered filter medium formed by sintering metal long fibers or metal powder can be used in addition to a knitted wire, and a sintered filter medium is preferable in terms of filtration accuracy and filter life.

(V) Gear pump In order to improve the thickness accuracy, it is important to reduce the fluctuation of the discharge amount. A gear pump is provided between the extruder and the die, and a certain amount of cellulose acylate resin is supplied from the gear pump. Is effective. A gear pump is accommodated in a state where a pair of gears consisting of a drive gear and a driven gear are engaged with each other, and the drive gear is driven to engage and rotate the two gears so that a melted state is generated from the suction port formed in the housing. Resin is sucked into the cavity, and a certain amount of the resin is discharged from a discharge port formed in the housing. Even if there is a slight fluctuation in the resin pressure at the front end of the extruder, the fluctuation is absorbed by using a gear pump, the fluctuation in the resin pressure downstream of the film forming apparatus becomes very small, and the thickness fluctuation is improved. By using a gear pump, it is possible to keep the fluctuation range of the resin pressure in the die portion within ± 1%.
In order to improve the quantitative supply performance by the gear pump, a method of controlling the pressure before the gear pump to be constant by changing the number of rotations of the screw can also be used. In addition, a high-precision gear pump using three or more gears that eliminate the gear pump gear variation is also effective.

Other advantages of using a gear pump are that the pressure at the screw tip can be reduced to form a film, reducing energy consumption, preventing rise in resin temperature, improving transport efficiency, reducing residence time in the extruder, L / D can be expected to be shortened. Also, when using a filter to remove foreign matter, if there is no gear pump, the amount of resin supplied from the screw may fluctuate as the filtration pressure rises. It can be resolved. On the other hand, the disadvantages of gear pumps are that the length of the equipment becomes longer depending on the equipment selection method, the residence time of the resin becomes longer, and the shearing stress of the gear pump section may cause the molecular chain to break. is required.
The preferred residence time of the resin from the supply port through the extruder until it exits the die is 2 minutes to 60 minutes, more preferably 3 minutes to 40 minutes, and even more preferably 4 minutes to 30 minutes. is there.

  Since the flow of the polymer for bearing circulation of the gear pump becomes worse, the polymer seal in the drive part and the bearing part becomes worse, and there is a problem that the fluctuation of the metering and liquid feed pressure increases. It is necessary to design a gear pump (especially clearance) in accordance with the melt viscosity. In some cases, the staying part of the gear pump causes deterioration of the thermoplastic resin, so that a structure with as little staying as possible is preferable. The polymer tube and adapter that connect the extruder and gear pump or gear pump and die, etc. must also have a design with as little stagnation as possible, and in order to stabilize the extrusion pressure of thermoplastic resins with high temperature dependence of melt viscosity, It is preferable to minimize the temperature variation. Generally, a band heater having a low equipment cost is often used for heating the polymer tube, but it is more preferable to use an aluminum cast heater with less temperature fluctuation. Further, in the extruder as described above, it is preferable that the barrel of the extruder is heated and melted with a heater divided into 3 to 20.

(vi) Die The thermoplastic resin is melted by the extruder configured as described above, and the molten resin is continuously sent to the die via a filter and a gear pump as necessary. As long as the die is designed so that the molten resin stays in the die, any type of commonly used T die, fishtail die, and hanger coat die may be used. There is no problem in placing a static mixer for improving the uniformity of the resin temperature immediately before the T die. The clearance of the T-die exit portion is generally 1.0 to 5.0 times the film thickness, preferably 1.2 to 3 times, and more preferably 1.3 to 2 times. When the lip clearance is 1.0 times smaller than the film thickness, it is difficult to obtain a good sheet by film formation. Further, when the lip clearance is larger than 5.0 times the film thickness, the sheet thickness accuracy is lowered, which is not preferable. The die is a very important facility for determining the thickness accuracy of the film, and a die that can control the thickness adjustment severely is preferable. Normally, the thickness can be adjusted at intervals of 40 to 50 mm, but preferably a type capable of adjusting the film thickness at intervals of 35 mm or less, more preferably at intervals of 25 mm or less. Further, in order to improve the uniformity of the film-forming film, it is important to design as little as possible of the temperature unevenness of the die and the flow velocity unevenness in the width direction. An automatic thickness adjustment die that measures the downstream film thickness, calculates the thickness deviation, and feeds back the result to the die thickness adjustment is also effective in reducing the thickness fluctuation in long-term continuous production.
For production of a film, a single-layer film forming apparatus with a low equipment cost is generally used. However, in some cases, a film having two or more types of structures can also be manufactured using a multilayer film forming apparatus in order to provide a functional layer on an outer layer. Is possible. In general, the functional layer is preferably thinly laminated on the surface layer, but the layer ratio is not particularly limited.

  The melt viscosity of the thermoplastic resin at the die outlet is preferably 100 Pa · s to 2000 Pa · s, more preferably 200 Pa · s to 1500 Pa · s, and particularly preferably 500 Pa · s to 1000 Pa · s. When the melt viscosity is in the range of 100 Pa · s to 2000 Pa · s, a film having a small film thickness variation and a reduced surface roughness can be formed.

(vii) Casting According to the above method, the molten resin extruded from the die onto the sheet is cooled and solidified on the casting drum to obtain a film. At this time, it is preferable to use a method such as an electrostatic application method, an air knife method, an air chamber method, a vacuum nozzle method, or a touch roll method to increase the adhesion between the casting drum and the melt-extruded sheet. Such an adhesion improving method may be performed on the entire surface of the melt-extruded sheet or a part thereof.

  In the present invention, it is particularly preferable to use a touch roll method in which a sheet-like thermoplastic resin is formed on the casting drum using a touch roll at the time of casting. In this method, the melt discharged from the die is sandwiched between a casting drum and a touch roll and solidified by cooling. As a result, the non-uniformity when extruded from the die as described above can be improved. That is, since the touch roll can be made to have a uniform temperature by passing a heating medium inside, the resin can be cooled and solidified at a uniform temperature over the entire width by sandwiching the molten resin, thereby further cooling the resin more uniformly. Each ΔRe and ΔRth generated by the residual strain can be reduced. If the cooling temperature is uneven, distortion occurs partially when solidifying by cooling. For this reason, a melt is rapidly cooled by using a touch roll, the passage time of Tg + 40 degreeC-Tg is shortened, and the thickness reduction in the meantime can be decreased. Furthermore, since the melt is pressed from both sides by the touch roll and the casting drum, the vibration of the melt can be suppressed by disturbance, and the occurrence of the horizontal dump can be reduced.

The touch roll is usually made of a rigid material, but if it is too rigid, residual strain is likely to occur when the melt from the die is sandwiched between the rolls, further promoting partial strain. For this reason, it is preferable that the material of the touch roll has elasticity. As a result, excessive surface pressure can be absorbed by deformation of the touch roll, and distortion can be suppressed. In order to give elasticity to the roll, it is necessary to make the outer cylinder thickness of the roll thinner than a normal roll, and the outer wall thickness Z is preferably 0.05 mm to 7.0 mm, more preferably 0.2 mm to 5.0 mm. More preferably, it is 0.3 mm-3.5 mm. The touch roll may be installed on a metal shaft, and a heat medium (fluid) may be passed between them. For example, an elastic layer is provided between the outer cylinder and the metal shaft, and the heat medium (fluid) is provided between the outer cylinders. The ones that are satisfied are listed.
Thus, since the touch roll has low elasticity, when it is brought into contact with the casting roll, it is elastically deformed into a concave shape by the pressing. Therefore, since the touch roll and the casting roll are in surface contact with the cooling roll, the pressure is dispersed and a low surface pressure can be achieved. For this reason, uniform cooling can be achieved without leaving a residual strain in the film sandwiched therebetween. The linear pressure of the preferred touch roll is 9.8 N / cm to 980 N / cm (1 kgf / cm to 100 kgf / cm), more preferably 19.6 N / cm to 784 N / cm (2 kgf / cm to 80 kgf / cm), and further preferably Is 29.4 N / cm to 588 N / cm (3 kgf / cm to 60 kgf / cm). The linear pressure referred to here is a value obtained by dividing the force applied to the touch roll by the width of the discharge port of the die. If the linear pressure is less than 9.8 N / cm, the pressing force of the touch roll is weak and it is difficult to correct in-plane non-uniformity. On the other hand, when the linear pressure exceeds 980 N / cm, it is difficult to apply a uniform linear pressure over the entire width (the roll is bent and the linear pressure tends to concentrate at both ends and the center), and non-uniformity is likely to increase.
The surface temperature of the touch roll is preferably set to 60 ° C to 160 ° C, more preferably 70 ° C to 150 ° C, and still more preferably 80 ° C to 140 ° C. Such temperature control can be achieved by passing a temperature-controlled liquid or gas through these rolls.
The surface of the touch roll and the casting roll is preferably a mirror surface, and the arithmetic average height Ra is 100 nm or less, preferably 50 nm or less, more preferably 25 nm or less. Specifically, for example, JP-A-11-314263, JP-A-2002-36332, JP-A-11-235747, WO97 / 28950, JP-A-2004-216717, JP-A-2003-145609. The listed ones can be used.

In the method for producing a thermoplastic film of the present invention, the melt is formed using the touch roll as described above, so that the elastic modulus of the thermoplastic film is preferably 2.9 kN / mm ² or less, more preferably 1.2 kN. / Mm ^{2 to} 2.8 kN / mm ² , more preferably 1.5 kN / mm ²
It can be set to ˜2.7 kN / mm ² . This is because by using the touch roll in casting, the molten resin (melt) can be rapidly cooled between the casting roll and the touch roll, so that the crystal growth can be suppressed and the elastic modulus can be lowered.

  Furthermore, since the melt having a large free volume at a high temperature is cooled and solidified as it is, it becomes a low-density film and the elastic modulus is lowered. Thus, by making it low elasticity modulus, the shrinkage stress of the width direction generate | occur | produced by neck-in can be made small, and the retardation change by a residual strain can be made small. Further, when a polarizing plate is produced by laminating a cellulose acylate film using the present invention, warping and peeling can be reduced because the stress is small when the elastic modulus is small.

  More preferably, a plurality of casting drums (rolls) are used for gradual cooling (among these, the touch roll is used so as to touch the first casting roll on the most upstream side (the one closer to the die)). ). In general, it is relatively common to use three cooling rolls, but this is not a limitation. The diameter of the roll is preferably 50 mm to 5000 mm, more preferably 100 mm to 2000 mm, and still more preferably 150 mm to 1000 mm. The interval between the plurality of rolls is preferably 0.3 mm to 300 mm, more preferably 1 mm to 100 mm, and still more preferably 3 mm to 30 mm. The surface temperature of the casting drum is preferably 60 ° C to 160 ° C, more preferably 70 ° C to 150 ° C, and further preferably 80 ° C to 140 ° C.

  Moreover, it is preferable to use a casting drum for heat treatment because a method of carrying a heat treatment by conveying a thermoplastic film on a roll set at a heat treatment temperature is preferable. When forming a film, it is preferable to use a plurality of (for example, three) casting drums. In that case, the first casting drum is set to Tg or less to cool the melt and suppress distortion generated during film formation. It is preferable to use the second and subsequent casting drums for the heat treatment. The surface temperature of the casting drum used for the heat treatment may be any temperature as long as the resin can be peeled off from the drum, but for the above-mentioned reasons, it is preferably Tg to Tg + 60 ° C., more preferably Tg to Tg + 50 ° C., more preferably Tg to Tg + 40. ° C. The number of heat relaxation casting drums combined with the number of temperature cooling drums is generally three, but is not limited thereto.

Then, it peels off from a casting drum, winds up after passing through a nip roll. The winding speed is preferably 10 m / min to 100 m / min, more preferably 15 m / min to 80 m / min, still more preferably 20 m / min to 70 m / min.
The film forming width is 0.7 m to 5 m, more preferably 1 m to 4 m, and still more preferably 1.3 m to 3 m. The thickness of the thermoplastic film thus obtained is preferably 30 μm to 400 μm, more preferably 40 μm to 300 μm, still more preferably 50 μm to 200 μm.

It is also preferable to trim both ends before winding. As the trimming cutter, any type of rotary cutter, shear blade, knife, or the like may be used. As for the material, either carbon steel or stainless steel may be used. In general, it is preferable to use a cemented carbide blade or a ceramic blade because the life of the blade is long and the generation of chips is suppressed. The portion cut off by trimming may be crushed and used again as a raw material.
Further, it is also preferable to perform a thickness increasing process (knurling process) at one or both ends before winding. The height of the unevenness due to the thickness increasing process is preferably 1 μm to 200 μm, more preferably 10 μm to 150 μm, and still more preferably 20 μm to 100 μm. Thickening processing may be convex on both sides or convex on one side. The width of the thickness increasing process is preferably 1 mm to 50 mm, more preferably 3 mm to 30 mm, and still more preferably 5 mm to 20 mm. Extrusion can be performed at room temperature to 300 ° C.

Moreover, it is also preferable from a viewpoint of scratch prevention to attach a lami film at least on one side before winding. The thickness of the laminated film is preferably 5 μm to 200 μm, preferably 10 μm to 150 μm, and preferably 15 μm to 100 μm. The material is not particularly limited, such as polyethylene, polyester, and polypropylene.
A preferable winding tension is 1 kg / m width to 50 kg / width, more preferably 2 kg / m width to 40 kg / width, and further preferably 3 kg / m width to 20 kg / width. When the winding tension is smaller than 1 kg / m width, it is difficult to wind the film uniformly. On the other hand, when the winding tension exceeds 50 kg / width, the film becomes tightly wound, not only the appearance of the winding is deteriorated, but also the bump portion of the film extends due to the creep phenomenon, and the film wave This is not preferable because it causes a cause or residual birefringence due to the elongation of the film. It is preferable that the winding tension is detected by tension control in the middle of the line and wound while being controlled so as to have a constant winding tension. If there is a difference in film temperature depending on the location of the film production line, the length of the film may be slightly different due to thermal expansion. It is necessary to prevent tension.

  The winding tension can be wound at a constant tension by controlling the tension control. However, it is more preferable that the winding tension is tapered to an appropriate winding tension according to the wound diameter. Generally, the tension is gradually reduced as the winding diameter increases, but in some cases, it may be preferable to increase the tension as the winding diameter increases.

<Extension>
Therefore, it is preferable that the thermoplastic film of the present invention is longitudinally stretched and / or laterally stretched. Either one of the longitudinal stretching and the lateral stretching may be performed, or both may be performed. Further, the longitudinal stretching and the lateral stretching may each be performed once, or may be performed a plurality of times, and the longitudinal stretching and the lateral stretching may be performed simultaneously.

The draw ratio in this invention is calculated | required using the following formula | equation.
Elongation ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / (Length before stretching)

  Such stretching may be performed in the longitudinal direction using two or more pairs of nip rolls with increased peripheral speed on the outlet side (longitudinal stretching), and both ends of the film are gripped with chucks and are orthogonally crossed (longitudinal). In a direction perpendicular to the direction) (lateral stretching). Moreover, you may use the simultaneous biaxial stretching method as described in Unexamined-Japanese-Patent No. 2000-37772, Unexamined-Japanese-Patent No. 2001-113591, and Unexamined-Japanese-Patent No. 2002-103445.

  If the unstretched film of the present invention is used, the film can be stretched with a small residual strain, and the retardation can be controlled with a small warp after a long period of time. The stretching method will be described in detail below.

Specifically, it is preferable to use the following stretching method.
(1) Longitudinal Stretching Longitudinal stretching can be achieved by installing two pairs of nip rolls and heating the gap between them so that the peripheral speed of the outlet side nip roll is faster than the peripheral speed of the inlet side nip roll. At this time, the expression of retardation (Rth) in the thickness direction can be changed by changing the distance (L) between the nip rolls and the film width (W) before stretching. When L / W (referred to as aspect ratio) exceeds 2 and is 50 or less (long span stretching), Rth can be decreased, and when the aspect ratio is 0.01 to 0.3 (short span stretching), Rth can be increased. These are appropriately used according to the purpose (target value of Rth). Details will be described below.

(1-1) Long span stretching The film is stretched as it is stretched. At this time, the film is reduced in thickness and width to reduce the volume change. At this time, shrinkage in the width direction is limited by friction between the nip roll and the film. For this reason, when the nip roll interval is increased, it is easy to contract in the width direction, and thickness reduction can be suppressed. When the thickness reduction is large, the same effect as that in which the film is compressed in the thickness direction is obtained. On the contrary, when the aspect ratio is large and the thickness reduction is small, Rth hardly appears and low Rth can be realized.
Furthermore, if the aspect ratio is long, the uniformity in the width direction can be improved. This is due to the following reason.
• The film tends to shrink in the width direction as it is stretched. At the central portion in the width direction, both sides thereof also try to contract in the width direction, so that it becomes a tug of war and cannot be contracted freely.
-On the other hand, the film width direction end part is in a tug-of-war state only on one side and can contract relatively freely.
-The difference in shrinkage behavior associated with the stretching between both ends and the central portion becomes stretching unevenness in the width direction.
Due to such non-uniformity between both ends and the center, retardation in the width direction and axial deviation (orientation angle distribution of slow axis) occur. On the other hand, since long span stretching is performed slowly between two long nip rolls, uniformity of these non-uniformities (molecular orientation becomes uniform) proceeds during stretching. On the other hand, in normal longitudinal stretching (aspect ratio = more than 0.3 and less than 2), such homogenization does not occur.

The aspect ratio exceeds 2 and is preferably 50 or less, more preferably 3 to 40, and still more preferably 4 to 20. The stretching temperature is preferably (Tg−5 ° C.) to (Tg + 100) ° C., more preferably (Tg) to (Tg + 50) ° C., and further preferably (Tg + 5) to (Tg + 30) ° C. The draw ratio is preferably 1.05 to 3 times, more preferably 1.05 to 1.7 times, and still more preferably 1.05 to 1.4 times. Such long span stretching may be performed in multiple stages with three or more pairs of nip rolls as long as the longest aspect ratio is within the above range.
Such long span stretching may be performed by heating the film between two pairs of nip rolls separated by a predetermined distance. The heating method is a heater heating method (infrared heater, halogen heater, panel heater, etc. above or below the film). Or heating by radiant heat) or a zone heating method (heating in a zone in which hot air or the like is blown and adjusted to a predetermined temperature) may be used. In the present invention, the zone heating method is preferable from the viewpoint of uniformity of the stretching temperature. At this time, the nip roll may be installed in the stretching zone or out of the zone, but in order to prevent the film and the nip roll from sticking, it is preferably out of the zone. It is also preferable to preheat the film before such stretching, and the preheating temperature in this case is preferably (Tg−80 ° C.) to (Tg + 100 ° C.).

By such stretching, a film having an Re value of preferably 0 to 200 nm, more preferably 10 to 200 nm, and even more preferably 15 to 100 nm is obtained. Further, by such stretching, a film having an Rth value of preferably 30 to 500 nm, more preferably 50 to 400 nm, and still more preferably 70 to 350 nm is obtained. By this stretching method, the ratio of Rth and Re (Rth / Re) can be, for example, 0.4 to 0.6, preferably 0.45 to 0.55. Furthermore, by such stretching, both the Re value and the Rth value can be changed to, for example, 5% or less, preferably 4% or less, more preferably 3% or less.
By such stretching, the ratio of the film width before and after stretching (film width after stretching / film width before stretching) is, for example, 0.5 to 0.9, preferably 0.6 to 0.85, more preferably It can be set to 0.65 to 0.83.

(1-2) Short span stretching The aspect ratio (L / W) is, for example, more than 0.01 and less than 0.3, preferably 0.03 to 0.25, more preferably 0.05 to 0.2. Perform longitudinal stretching (short span stretching). By performing stretching at an aspect ratio (L / W) in such a range, neck-in (shrinkage in the direction orthogonal to stretching accompanying stretching) can be reduced. Although the width and thickness are reduced to compensate for stretching in the stretching direction, such short span stretching suppresses width shrinkage and preferentially reduces the thickness. As a result, the film is compressed in the thickness direction, and the orientation (plane orientation) in the thickness direction proceeds. As a result, the Rth value, which is a measure of the anisotropy in the thickness direction, tends to increase. On the other hand, conventionally, the aspect ratio (L / W) is generally about 1 (0.7 to 1.5). This is usually done by installing a heater for heating between the nip rolls, but if the L / W becomes too large, the film cannot be heated uniformly with the heater, uneven stretching tends to occur, and if the L / W is too small. This is because the heater is difficult to install and cannot be heated sufficiently.
The short span stretching described above can be performed by changing the conveyance speed between two or more pairs of nip rolls, but unlike a normal roll arrangement, the two pairs of nip rolls are slanted (the rotational axes of the front and rear nip rolls are shifted up and down). This can be achieved by arranging.
Accordingly, since a heater for heating cannot be installed between the nip rolls, it is preferable to raise the temperature of the film by flowing a heating medium in the nip rolls. Furthermore, it is also preferable to provide a preheating roll in which a heating medium is flowed inside before the entrance side nip roll, and to heat the film before stretching. The stretching temperature is preferably (Tg-5 ° C) to (Tg + 100) ° C, more preferably (Tg) to (Tg + 50) ° C, still more preferably (Tg + 5) to (Tg + 30) ° C, and a preferable preheating temperature. Is Tg-80 ° C to Tg + 100 ° C.

Here, the long span stretching and the short span stretching will be described in detail.
FIG. 2 is a schematic configuration diagram of the film manufacturing apparatus 10 in the case of manufacturing a thermoplastic film by melt film formation when performing long span stretching.
The film manufacturing apparatus 10 is an apparatus for manufacturing a thermoplastic film F that can be used in a liquid crystal display device or the like. After the pelletized cellulose acylate resin or cycloolefin resin, which is a raw material of the thermoplastic film F, is introduced into the dryer 12 and dried, the pellet is extruded by the extruder 14 and supplied to the filter 18 by the gear pump 16. Next, the foreign matter is filtered by the filter 18 and pushed out from the die 20. Thereafter, the film is sandwiched between the cast drum 28 and the touch roll 24 and passes between the cast drum 28 and the roll 26 to be solidified to form an unstretched film Fa having a predetermined surface roughness. And this unstretched film Fa is supplied to the longitudinal stretch part 30 which performs long span stretching.
In the longitudinal stretching section 30, the unstretched film Fa is stretched in the transport direction between the inlet side nip roll 32 and the outlet side nip roller 34 to obtain a longitudinally stretched film Fb. FIG. 3 is a perspective explanatory view of the longitudinal stretching unit 30, and the longitudinal stretching aspect ratio (L / W) is determined by the distance L between the inlet-side nip roll 32 and the outlet-side nip roller 34 and the inlet-side nip roll 32. And the width W of the outlet side nip roller 34 in the length direction. Next, the longitudinally stretched film Fb is adjusted to a predetermined preheating temperature by passing through the preheating unit 36 and then supplied to the lateral stretching unit 42.
In the laterally stretched portion 42, the longitudinally stretched film Fb is stretched in the width direction orthogonal to the transport direction to form a laterally stretched film Fc. Then, the laterally stretched film Fc is supplied to the heat fixing unit 44 and wound up by the winding unit 46, whereby the thermoplastic film F that is the final product in which the orientation angle and retardation are adjusted is manufactured. The transversely stretched film Fc may be further subjected to heat relaxation treatment after passing through the heat fixing portion 44.

On the other hand, FIG. 4 is a schematic configuration diagram of a film manufacturing apparatus 10a in which a longitudinal stretching unit 30a that performs short span stretching is used instead of the longitudinal stretching unit 30 that performs long span stretching shown in FIGS.
In this film manufacturing apparatus 10a, the unstretched film Fa is preheated to a predetermined temperature by the preheating rolls 33 and 35 and then supplied between the two sets of nip rolls 37 and 39 for longitudinal stretching. In this case, the nip rolls 37 and 39 are disposed in the vicinity of the transport direction of the unstretched film Fa and are disposed so that the height differs by a predetermined distance in the vertical direction. By disposing the nip rolls 37 and 39 in this way, the transport distance of the unstretched film Fa in the longitudinal stretching portion 30a can be secured, and the distance between the mechanisms disposed before and after the longitudinal stretching portion 30a can be shortened. The manufacturing apparatus 10a can be downsized.
FIG. 5 is an explanatory perspective view of the longitudinally stretched portion 30a, and the longitudinal stretch aspect ratio (L / W) is the distance L in the transport direction of the unstretched film Fa nipped by the nip rolls 37 and 39. , And the width W in the length direction of the nip rolls 37 and 39.

(2) Lateral stretching Re and Rth can be adjusted by combining longitudinal stretching and lateral stretching. Either longitudinal stretching or lateral uniaxial stretching may be used, but by combining the stretching in both directions, it is easy to adjust that the orientation in the stretching direction advances and the absolute value of Re increases excessively. Further, by combining the longitudinal stretching and the lateral stretching, there is an advantage that the longitudinal orientation and the lateral orientation are offset and Re can be reduced. Furthermore, since the film is stretched in both the vertical and horizontal directions, the thickness reduction is increased, the plane orientation is advanced, and Rth can be increased.
Either the longitudinal stretching or the lateral stretching may be performed first and may be performed at the same time, but a method of performing lateral stretching after the longitudinal stretching is more preferable. Thereby, an installation can be made compact. Although longitudinal stretching and lateral stretching may be performed independently or continuously, it is more preferable to perform them continuously.
The transverse stretching can be performed using, for example, a tenter. That is, the film is stretched by holding both ends in the width direction with clips and widening the film in the lateral direction. At this time, the stretching temperature can be controlled by sending wind at a desired temperature into the tenter. The stretching temperature is preferably (Tg-10) ° C to (Tg + 60) ° C, more preferably (Tg-5) ° C to (Tg + 45) ° C, and still more preferably (Tg) to (Tg + 30) ° C. A preferable draw ratio is 1.01 times to 4 times, more preferably 1.03 times to 3.5 times, and still more preferably 1.05 times to 2.5 times. The ratio of transverse stretching to longitudinal stretching (lateral stretching ratio / longitudinal stretching ratio) is preferably 1.1 to 100 or 0.9 to 0.01, more preferably 2 to 60 or 0.5 to 0.017, Preferably it is 4-40 or 0.25-0.025.

Preheating can be performed before such stretching, and heat treatment can be performed after stretching. By adopting such means, the Re and Rth distribution after stretching can be reduced, and the variation in orientation angle associated with bowing can be reduced. Either preheating or heat treatment may be performed, but it is more preferable to perform both. These preheating and heat treatment are preferably performed by holding with a clip, that is, preferably performed continuously with stretching.
Preheating is preferably performed at a temperature higher than the stretching temperature by 1 ° C to 50 ° C, more preferably 2 ° C to 40 ° C, and even more preferably 3 ° C to 30 ° C. The preheating time is preferably 1 second to 10 minutes, more preferably 5 seconds to 4 minutes, and further preferably 10 seconds to 2 minutes.
The heat treatment is preferably performed at a temperature lower than the stretching temperature by 1 ° C to 50 ° C, more preferably 2 ° C to 40 ° C, and even more preferably 3 ° C to 30 ° C. More preferably, the temperature is not more than the stretching temperature and not more than Tg. The preheating time is preferably 1 second to 10 minutes, more preferably 5 seconds to 4 minutes, and further preferably 10 seconds to 2 minutes.
Such preheating and heat treatment can reduce the variation in orientation angle and Re and Rth for the following reasons.
The film is stretched in the width direction and tends to become thin (neck-in) in the orthogonal direction (longitudinal direction).
-For this reason, the film before and after transverse stretching is pulled and stress is generated. However, both ends in the width direction are fixed by chucks and are not easily deformed by stress, and the central portion in the width direction is easily deformed. As a result, the stress caused by the neck-in is deformed into a bow shape and bowing occurs. As a result, in-plane Re and Rth unevenness and distribution of orientation axes occur.
In order to suppress this, if the temperature on the preheating side (before stretching) is increased and the temperature on the heat treatment (after stretching) is lowered, neck-in occurs on the high temperature side (preheating) with a lower elastic modulus, and heat treatment ( It becomes difficult to occur after stretching). That is, when heat setting is not performed, as shown in FIG. 6, a convex bowing is generated on the upstream side in the conveyance direction near the exit of the transverse stretching zone of the film F after transverse stretching. By performing heat fixing in the heat fixing part 44 immediately after the extending part 42, as shown in FIG. 7, it is possible to suppress the occurrence of bowing that is convex on the upstream side in the transport direction. Further, when preheating is performed in the preheating section 36 immediately before the lateral stretching section 42, the resin distribution easily spreads in the transport direction downstream near the entrance of the lateral stretching section 42, and uniform lateral stretching becomes possible. Convex bowing hardly occurs on the upstream side in the transport direction near the exit of the laterally extending portion 42. As a result, bowing after stretching can be suppressed.

  By such stretching, the fluctuations of Re and Rth depending on the location in the width direction and the longitudinal direction are both preferably 5% or less, more preferably 4% or less, and still more preferably 3% or less. Further, the orientation angle is preferably 90 ° ± 5 ° or less or 0 ° ± 5 ° or less, more preferably 90 ° ± 3 ° or less or 0 ° ± 3 ° or less, and 90 ° ± 1 ° or less. Or it is more preferable to set it as 0 degrees ± 1 degrees or less.

(3) Relaxation Further, dimensional stability can be improved by performing a relaxation treatment after the stretching. The thermal relaxation is preferably performed after longitudinal stretching, either after lateral stretching, or both, and more preferably after lateral stretching. The relaxation treatment may be performed online continuously after stretching, or may be performed offline after winding after stretching.
The thermal relaxation is preferably (Tg-50) ° C to (Tg + 30) ° C, more preferably (Tg-30) ° C to (Tg + 20) ° C, more preferably (Tg-15) ° C to (Tg + 10) ° C, preferably 1 second to 10 minutes, more preferably 5 seconds to 4 minutes, even more preferably 10 seconds to 2 minutes, preferably 0.1 kg / m to 20 kg / m, more preferably 1 kg / m to 16 kg / m, still more preferably 2 kg It is carried out while transporting at a tension of / m to 12 kg / m.

(4) Physical properties after stretching It is preferable that Re and Rth of the thermoplastic film longitudinally stretched, laterally stretched, and longitudinally and laterally stretched as described above satisfy the following formulas (R-1) and (R-2).
Formula (R-1): 0 nm ≦ Re ≦ 200 nm
Formula (R-2): 0 nm ≦ Rth ≦ 600 nm
(In the formula, Re represents the in-plane retardation of the thermoplastic film, and Rth represents the thickness direction retardation of the thermoplastic film.)

More preferably, Rth ≧ Re × 1.1
180 ≧ Re ≧ 10
400 ≧ Rth ≧ 50
More preferably, Rth ≧ Re × 1.2
150 ≧ Re ≧ 20
300 ≧ Rth ≧ 100
It is.

The angle θ formed by the film forming direction (longitudinal direction) and the slow axis of Re of the film is preferably closer to 0 °, + 90 °, or −90 °. That is, in the case of longitudinal stretching, the angle θ is preferably as close to 0 °, preferably 0 ± 3 °, more preferably 0 ± 2 °, and further preferably 0 ± 1 °. In the case of transverse stretching, 90 ± 3 ° or −90 ± 3 ° is preferable, 90 ± 2 ° or −90 ± 2 ° is more preferable, and 90 ± 1 ° or −90 ± 1 ° is more preferable.
As for the thickness of the thermoplastic film after extending | stretching, all 15 micrometers-100 micrometers are preferable, More preferably, they are 20 micrometers-100 micrometers, More preferably, they are 30 micrometers-60 micrometers. The thickness unevenness is preferably 0% to 3% in both the longitudinal direction and the width direction, more preferably 0% to 2%, and still more preferably 0% to 1%.
In the present invention, it has been found that the warp occurring when stored for a long time can be further eliminated by carrying out heat stretching. This is presumably because the distortion that occurred during film formation, which causes warping, was eliminated in the hot stretching process.

<Processing of thermoplastic film>
The (transparent) thermoplastic film thus obtained may be used alone or in combination with a polarizing plate, and a liquid crystal layer or a layer with a controlled refractive index (low reflection) Layer) or a hard coat layer may be used. These can be achieved by the following steps.

(1) Surface treatment (i) Cellulose acylate film By performing the surface treatment, adhesion with each functional layer (for example, undercoat layer and back layer) can be improved. For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The “glow discharge treatment” here is a treatment for subjecting the film surface to a plasma treatment in the presence of a plasma-excitable gas.
The glow discharge treatment includes a low temperature plasma treatment that occurs under a low pressure gas of 10 ^{−3 to} 20 Torr (0.13 to 2700 Pa). Further, plasma treatment under atmospheric pressure is also a preferable glow discharge treatment. The plasma-excitable gas refers to a gas that is plasma-excited under the above-described conditions, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. Can be mentioned. Details of these are described in detail on pages 30 to 32 in the Journal of the Invention Association (Technology No. 2001-1745, issued on March 15, 2001, Invention Association). Note that, in the plasma treatment at atmospheric pressure which has been attracting attention in recent years, irradiation energy of 20 to 500 kGy is used, for example, under 10 to 1000 Kev, and more preferably irradiation energy of 20 to 300 kGy is used under 30 to 500 Kev.
Of these, alkali saponification is particularly preferable.

  The alkali saponification treatment may be immersed in a saponification solution (immersion method) or a saponification solution may be applied (application method). In the case of the dipping method, it is achieved by passing an aqueous solution of pH 10 to 14 such as NaOH or KOH through a bath heated to 20 ° C. to 80 ° C. for 0.1 minutes to 10 minutes, followed by neutralization, washing with water and drying. it can.

  In the case of the coating method, a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method can be used. The solvent of the alkali saponification coating solution has good wettability because it is applied to the transparent support of the saponification solution, and the surface state remains good without forming irregularities on the surface of the transparent support by the saponification solution solvent. It is preferred to select a solvent to keep. Specifically, an alcohol solvent is preferable, and isopropyl alcohol is particularly preferable. An aqueous solution of a surfactant can also be used as a solvent. The alkali of the alkali saponification coating solution is preferably an alkali that dissolves in the solvent, and more preferably KOH or NaOH. The pH of the saponification coating solution is preferably 10 or more, more preferably 12 or more. The reaction conditions during alkali saponification are preferably 1 second to 5 minutes at room temperature, more preferably 5 seconds to 5 minutes, and particularly preferably 20 seconds to 3 minutes. After the alkali saponification reaction, it is preferable to wash the surface on which the saponification solution is applied with water or with an acid and then with water. Further, the coating-type saponification treatment and the alignment film uncoating described later can be performed continuously, and the number of steps can be reduced. Specific examples of these saponification methods are described in JP-A-2002-82226 and WO02 / 46809.

It is also preferable to provide an undercoat layer for adhesion to the functional layer. This layer may be coated after the surface treatment or may be coated without the surface treatment. Details of the undercoat layer are described on page 32 of the Japan Society for Invention and Innovation (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention).
These surface treatment and undercoating processes can be incorporated at the end of the film forming process, can be performed alone, or can be performed in the functional layer application process described later.

(ii) Thermoplastic film other than cellulose acylate A thermoplastic film such as a saturated norbornene film may be subjected to glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment. The glow discharge treatment here is a treatment for subjecting the film surface to a plasma treatment in the presence of a plasma-excitable gas as described above.
The glow discharge treatment includes a low temperature plasma treatment that occurs under a low pressure gas of 10 ^{−3 to} 20 Torr (0.13 to 2700 Pa). Further, plasma treatment under atmospheric pressure is also a preferable glow discharge treatment. The plasma-excitable gas refers to a gas that is plasma-excited under the above-described conditions, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. Can be mentioned. Details of these are described in detail on pages 30 to 32 in the Journal of the Invention Association (Technology No. 2001-1745, issued on March 15, 2001, Invention Association). Note that, in the plasma treatment at atmospheric pressure which has been attracting attention in recent years, irradiation energy of 20 to 500 kGy is used, for example, under 10 to 1000 Kev, and more preferably irradiation energy of 20 to 300 kGy is used under 30 to 500 Kev.
Of these, glow discharge treatment, corona treatment, and flame treatment are particularly preferred.

It is also preferable to provide an undercoat layer for adhesion to the functional layer. This layer may be coated after the surface treatment or may be coated without the surface treatment. Details of the undercoat layer are described on page 32 of the Japan Society for Invention and Innovation (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention).
These surface treatment and undercoating processes can be incorporated at the end of the film forming process, can be performed alone, or can be performed in the functional layer application process described later.

(2) Application of functional layer The thermoplastic film of the present invention is described in detail on pages 32 to 45 in the Japan Society for Invention and Innovation Technical Report (Technical Number 2001-1745, published on March 15, 2001, Japan Society for Invention). It is preferable to combine the functional layers. Among these, application of a polarizing layer (polarizing plate), application of an optical compensation layer (optical compensation sheet), and application of an antireflection layer (antireflection film) are preferable.

(A) Application of polarizing layer (preparation of polarizing plate)
The polarizing plate of the present invention usually has a polarizing film on a substrate, and is characterized by laminating at least one thermoplastic film of the present invention.
(A-1) Material used Currently, a commercially available polarizing layer is obtained by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing iodine or dichroic dye to penetrate into the binder. It is common to make it. The polarizing film is manufactured by Optiva Inc. A coating type polarizing film typified by can also be used. Iodine and dichroic dye in the polarizing film exhibit deflection performance by being oriented in the binder. As the dichroic dye, an azo dye, stilbene dye, pyrazolone dye, triphenylmethane dye, quinoline dye, oxazine dye, thiazine dye or anthraquinone dye is used. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (eg, sulfo, amino, hydroxyl). For example, the compound as described in Invention Association public technique, public technical number 2001-1745, page 58 (issue date March 15, 2001) can be mentioned.

  As the binder for the polarizing film, either a polymer that can be crosslinked per se or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the binder include methacrylate copolymer, styrene copolymer, polyolefin, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylolacrylamide) described in paragraph No. [0022] of JP-A-8-338913. , Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like. Silane coupling agents can be used as the polymer. Water-soluble polymers (eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, modified polyvinyl alcohol) are preferred, gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferred, and polyvinyl alcohol and modified polyvinyl alcohol are most preferred. . It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000. The modified polyvinyl alcohol is described in JP-A-8-338913, JP-A-9-152509 and JP-A-9-316127. Two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.

The lower limit of the binder thickness is preferably 10 μm. The upper limit of the thickness is preferably as thin as possible from the viewpoint of light leakage of the liquid crystal display device. It is preferably not more than a commercially available polarizing plate (about 30 μm), preferably 25 μm or less, and more preferably 20 μm or less.
The binder of the polarizing film may be cross-linked. A polymer or monomer having a crosslinkable functional group may be mixed in the binder, or a crosslinkable functional group may be imparted to the binder polymer itself. Crosslinking can be performed by light, heat, or pH change, and a binder having a crosslinked structure can be formed. The crosslinking agent is described in US Reissue Patent 23297. Boron compounds (eg, boric acid, borax) can also be used as a crosslinking agent. The addition amount of the crosslinking agent in the binder is preferably 0.1 to 20% by mass with respect to the binder. The orientation of the polarizing element and the wet heat resistance of the polarizing film are improved.
Even after the crosslinking reaction is completed, the unreacted crosslinking agent is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By doing in this way, a weather resistance improves.

(A-2) Stretching of polarizing layer The polarizing film is preferably dyed with iodine or a dichroic dye after stretching the polarizing film (stretching method) or rubbing (rubbing method).
In the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, and more preferably 3.0 to 10.0 times. Stretching can be performed by dry stretching in air. Moreover, you may implement wet extending | stretching in the state immersed in water. The stretch ratio of dry stretching is preferably 2.5 to 5.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 10.0 times. Stretching may be performed parallel to the MD direction (parallel stretching), or may be performed in an oblique direction (oblique stretching). These stretching operations may be performed once or divided into several times. By dividing into several times, it is possible to stretch more uniformly even at high magnification.

a) Parallel stretching method Prior to stretching, it is preferable to swell the PVA film. The degree of swelling is 1.2 to 2.0 times (mass ratio between before swelling and after swelling). Thereafter, the film is stretched at a bath temperature of 15 to 50 ° C., particularly 17 to 40 ° C. in an aqueous medium bath or a dye bath for dissolving a dichroic substance while being continuously conveyed through a guide roll or the like. Stretching can be achieved by gripping with two pairs of nip rolls and increasing the conveyance speed of the subsequent nip roll to be higher than that of the previous nip roll. The draw ratio is based on the length ratio after stretching / initial state (hereinafter the same), but the preferred draw ratio is 1.2 to 3.5 times, especially 1.5 to 3.0 times from the viewpoint of the above-mentioned effects. is there. Then, it is made to dry at 50 to 90 degreeC, and a polarizing film is obtained.

b) Diagonal Stretching Method For this purpose, a method of stretching using a tenter projecting in an obliquely inclined direction as described in JP-A-2002-86554 can be used. Since this stretching is performed in the air, it is necessary to make it easy to stretch by adding water in advance. The preferred water content is 5% to 100%, more preferably 10% to 100%.
The temperature during stretching is preferably 40 ° C to 90 ° C, more preferably 50 ° C to 80 ° C. The humidity is preferably 50% relative humidity to 100% relative humidity, more preferably 70% relative humidity to 100% or less relative humidity, and still more preferably 80% relative humidity to 100% relative humidity. The traveling speed in the longitudinal direction is preferably 1 m / min or more, more preferably 3 m / min or more.
After the completion of stretching, the film is dried at 50 to 100 ° C., more preferably 60 to 90 ° C., for 0.5 to 10 minutes. More preferably, it is 1 minute to 5 minutes.
The absorption axis of the polarizing film thus obtained is preferably 10 ° to 80 °, more preferably 30 ° to 60 °, and still more preferably 45 ° (40 ° to 50 °).

(I-3) Bonding A polarizing plate is prepared by bonding the thermoplastic film after the surface treatment and a polarizing layer prepared by stretching. The laminating direction is preferably performed so that the casting axis direction of the thermoplastic film and the stretching axis direction of the polarizing plate are 45 °.
The adhesive for bonding is not particularly limited, but examples thereof include PVA resins (including modified PVA such as acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group) and boron compound aqueous solution. preferable. The thickness of the adhesive layer is preferably 0.01 to 10 μm after drying, and particularly preferably 0.05 to 5 μm.
The polarizing plate thus obtained preferably has a higher light transmittance, and preferably has a higher degree of polarization. The transmittance of the polarizing plate is preferably in the range of 30 to 50%, more preferably in the range of 35 to 50%, and most preferably in the range of 40 to 50% in light having a wavelength of 550 nm. . The degree of polarization is preferably in the range of 90 to 100%, more preferably in the range of 95 to 100%, and most preferably in the range of 99 to 100% in light having a wavelength of 550 nm.
Furthermore, the polarizing plate thus obtained can be laminated with a λ / 4 plate to produce circularly polarized light. In this case, lamination is performed so that the slow axis of λ / 4 and the absorption axis of the polarizing plate are 45 °. At this time, λ / 4 is not particularly limited, but more preferably has a wavelength dependency such that the lower the wavelength, the smaller the retardation. Furthermore, it is preferable to use a polarizing film having an absorption axis inclined by 20 ° to 70 ° with respect to the longitudinal direction and a λ / 4 plate made of an optically anisotropic layer made of a liquid crystalline compound.

(B) Application of optical compensation layer (production of optical compensation sheet)
The optical compensation sheet is characterized by using the thermoplastic film of the present invention, and usually has an optical compensation layer on a substrate.
The optically anisotropic layer is for compensating for the liquid crystal compound in the liquid crystal cell in the black display of the liquid crystal display device, forms an alignment film on the thermoplastic film, and further provides the optically anisotropic layer. Is formed.

(B-1) Alignment film An alignment film is provided on the surface-treated thermoplastic film. This film has a function of defining the alignment direction of liquid crystalline molecules. However, if the alignment state is fixed after aligning the liquid crystalline compound, the alignment film plays the role, and thus is not necessarily an essential component of the present invention. That is, it is possible to produce the polarizing plate of the present invention by transferring only the optically anisotropic layer on the alignment film in which the alignment state is fixed onto the polarizer.
The alignment film is an organic compound (eg, ω-tricosanoic acid) formed by rubbing treatment of an organic compound (preferably polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodgett method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known.

The alignment film is preferably formed by polymer rubbing treatment. In principle, the polymer used for the alignment film has a molecular structure having a function of aligning liquid crystal molecules.
In the present invention, in addition to the function of aligning liquid crystalline molecules, a cross-linking having a function of aligning a side chain having a crosslinkable functional group (eg, double bond) to the main chain or aligning liquid crystalline molecules. It is preferable to introduce a functional functional group into the side chain.

  As the polymer used in the alignment film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the polymer include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylol) described in paragraph No. [0022] of JP-A-8-338913. Acrylamide), polyester, polyimide, vinyl acetate copolymer, carboxymethylcellulose, polycarbonate and the like. Silane coupling agents can be used as the polymer. Water-soluble polymers (eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, modified polyvinyl alcohol) are preferred, gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferred, and polyvinyl alcohol and modified polyvinyl alcohol are most preferred. . It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000.

  A side chain having a function of aligning liquid crystal molecules generally has a hydrophobic group as a functional group. The specific type of functional group is determined according to the type of liquid crystal molecule and the required alignment state. For example, the modifying group of the modified polyvinyl alcohol can be introduced by copolymerization modification, chain transfer modification or block polymerization modification. Examples of modifying groups include hydrophilic groups (carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amide groups, thiol groups, etc.), hydrocarbon groups having 10 to 100 carbon atoms, fluorine atoms Substituted hydrocarbon groups, thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azirinidyl groups, etc.), alkoxysilyl groups (trialkoxy, dialkoxy, monoalkoxy) and the like can be mentioned. As specific examples of these modified polyvinyl alcohol compounds, for example, paragraph numbers [0022] to [0145] in JP-A No. 2000-155216 and paragraph numbers [0018] to [0018] in JP-A No. 2002-62426 are described. [0022] and the like.

  When a side chain having a crosslinkable functional group is bonded to the main chain of the alignment film polymer, or a crosslinkable functional group is introduced into a side chain having a function of aligning liquid crystalline molecules, the alignment film polymer and the optically anisotropic film The polyfunctional monomer contained in the conductive layer can be copolymerized. As a result, not only between the polyfunctional monomer and the polyfunctional monomer, but also between the alignment film polymer and the alignment film polymer and between the polyfunctional monomer and the alignment film polymer is firmly bonded by a covalent bond. Therefore, the strength of the optical compensation sheet can be remarkably improved by introducing the crosslinkable functional group into the alignment film polymer.

  The crosslinkable functional group of the alignment film polymer preferably contains a polymerizable group in the same manner as the polyfunctional monomer. Specific examples include those described in paragraphs [0080] to [0100] in JP-A-2000-155216. Apart from the crosslinkable functional group, the alignment film polymer can also be crosslinked using a crosslinking agent.

Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole, and dialdehyde starch. Two or more kinds of crosslinking agents may be used in combination. Specific examples include compounds described in paragraphs [0023] to [024] in JP-A No. 2002-62426. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.
0.1-20 mass% is preferable with respect to a polymer, and, as for the addition amount of a crosslinking agent, 0.5-15 mass% is more preferable. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By adjusting in this way, even if the alignment film is used for a long time in a liquid crystal display device or left in a high temperature and high humidity atmosphere for a long time, sufficient durability without reticulation can be obtained. May occur.

  The alignment film can be basically formed by applying the polymer, which is an alignment film forming material, on a transparent support containing a crosslinking agent, followed by heat drying (crosslinking) and rubbing treatment. As described above, the crosslinking reaction may be performed at any time after coating on the transparent support. When a water-soluble polymer such as polyvinyl alcohol is used as the alignment film forming material, the coating solution is preferably a mixed solvent of an organic solvent (eg, methanol) having a defoaming action and water. The ratio of water: methanol is preferably 0: 100 to 99: 1, and more preferably 0: 100 to 91: 9. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of the layer surface of an alignment film and also an optical anisotropic layer reduces remarkably.

The alignment film is preferably applied by spin coating, dip coating, curtain coating, extrusion coating, rod coating, or roll coating. A rod coating method is particularly preferable. The film thickness after drying is preferably 0.1 to 10 μm. Heating and drying can be performed at 20 ° C to 110 ° C. In order to form sufficient cross-linking, 60 ° C to 100 ° C is preferable, and 80 ° C to 100 ° C is particularly preferable. The drying time can be 1 minute to 36 hours, preferably 1 minute to 30 minutes. The pH is preferably set to an optimum value for the crosslinking agent to be used. When glutaraldehyde is used, the pH is 4.5 to 5.5, and 5 is particularly preferable.
The alignment film is provided on the transparent support or the undercoat layer. The alignment film can be obtained by rubbing the surface after crosslinking the polymer layer as described above.
For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, a method of obtaining the orientation by rubbing the surface of the orientation film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. Generally, it is carried out by rubbing several times using a cloth or the like in which fibers having a uniform length and thickness are planted on average.

When industrially performing rubbing treatment, this is achieved by bringing a rotating rubbing roll into contact with the film with the polarizing layer being conveyed. ) Is preferably 30 μm or less. The film wrap angle on the rubbing roll is preferably 0.1 to 90 °. However, as described in JP-A-8-160430, a stable rubbing treatment can be obtained by winding 360 ° or more. As for the conveyance speed of a film, 1-100 m / min is preferable. It is preferable to select an appropriate rubbing angle in the range of 0 to 60 °. When used for a liquid crystal display device, 40 to 50 ° is preferable. 45 ° is particularly preferred.
The thickness of the alignment film thus obtained is preferably in the range of 0.1 to 10 μm.

Next, the liquid crystalline molecules of the optically anisotropic layer are aligned on the alignment film. Thereafter, if necessary, the alignment film polymer and the polyfunctional monomer contained in the optically anisotropic layer are reacted, or the alignment film polymer is crosslinked using a crosslinking agent.
The liquid crystalline molecules used in the optically anisotropic layer include rod-like liquid crystalline molecules and discotic liquid crystalline molecules. The rod-like liquid crystal molecules and the disk-like liquid crystal molecules may be high-molecular liquid crystals or low-molecular liquid crystals, and further include those in which low-molecular liquid crystals are cross-linked and no longer exhibit liquid crystallinity.

(B-2) Rod-like liquid crystal molecules The rod-like liquid crystal molecules include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoate esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano. Substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.
The rod-like liquid crystalline molecule includes a metal complex. In addition, a liquid crystal polymer containing a rod-like liquid crystalline molecule in a repeating unit can also be used as the rod-like liquid crystalline molecule. In other words, the rod-like liquid crystal molecule may be bonded to a (liquid crystal) polymer.
For rod-like liquid crystalline molecules, see Chapter 4, Chapter 7 and Chapter 11 of the Chemistry of the Quarterly Chemistry Vol. 22 (1994) The Chemical Society of Japan, and the 142th Committee of the Japan Society for the Promotion of Science. Described in Chapter 3.
The birefringence of the rod-like liquid crystal molecule is preferably in the range of 0.001 to 0.7.
The rod-like liquid crystal molecule preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably a radically polymerizable unsaturated group or a cationically polymerizable group. Specifically, for example, the polymerizable groups described in paragraphs [0064] to [0086] of JP-A-2002-62427 are described. Group and a polymerizable liquid crystal compound.

(B-3) Discotic liquid crystalline molecules The discotic liquid crystalline molecules include C.I. Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives described in C.I. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990); Kohne et al., Angew. Chem. 96, page 70 (1984) and the cyclohexane derivatives described in J. Am. M.M. Lehn et al. Chem. Commun. , 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), azacrown type and phenylacetylene type macrocycles are included.

As a discotic liquid crystalline molecule, a compound having liquid crystallinity in which a linear alkyl group, an alkoxy group, and a substituted benzoyloxy group are substituted radially as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule Is also included. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation. In the optically anisotropic layer formed from the discotic liquid crystalline molecules, the compound finally contained in the optically anisotropic layer does not need to be a discotic liquid crystalline molecule. Also included are compounds that have a group that reacts with heat or light, and that eventually polymerize or cross-link by reaction with heat or light to increase the molecular weight and lose liquid crystallinity. Preferred examples of the discotic liquid crystalline molecules are described in JP-A-8-50206. The polymerization of discotic liquid crystalline molecules is described in JP-A-8-27284.
In order to fix the discotic liquid crystalline molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecules. A compound in which the discotic core and the polymerizable group are bonded via a linking group is preferable, whereby the orientation state can be maintained even in the polymerization reaction. Examples thereof include compounds described in paragraphs [0151] to “0168” in JP-A No. 2000-155216.

  In the hybrid alignment, the angle between the major axis (disk surface) of the discotic liquid crystalline molecule and the surface of the polarizing film increases or decreases in the depth direction of the optically anisotropic layer and with increasing distance from the surface of the polarizing film. is doing. It is preferable that the angle between the major axis of the discotic liquid crystalline molecule and the plane of the polarizing film decreases as the distance increases. Furthermore, as the change of the angle between the major axis of the discotic liquid crystalline molecule and the plane of the polarizing film, the change includes continuous increase, continuous decrease, intermittent increase, intermittent decrease, continuous increase and continuous decrease, Alternatively, intermittent changes including increases and decreases are possible. The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if the angle between the major axis of the discotic liquid crystalline molecule and the plane of the polarizing film includes a region where the angle does not change, it may be increased or decreased as a whole. Furthermore, it is preferable that the angle changes continuously.

  The average direction of the major axis of the discotic liquid crystalline molecules on the polarizing film side can be generally adjusted by selecting a discotic liquid crystalline molecule or an alignment film material, or by selecting a rubbing treatment method. In addition, the major axis (disk surface) direction of the surface-side (air-side) discotic liquid crystalline molecules is generally adjusted by selecting the type of additive used together with the discotic liquid crystalline molecules or discotic liquid crystalline molecules. be able to. Examples of the additive used together with the discotic liquid crystalline molecule include a plasticizer, a surfactant, a polymerizable monomer and a polymer. The degree of change in the orientation direction of the major axis can be adjusted by selecting liquid crystal molecules and additives as described above.

(B-4) Other composition of optically anisotropic layer Along with the above liquid crystalline molecules, a plasticizer, a surfactant, a polymerizable monomer, etc. are used in combination, and the uniformity of the coating film, the strength of the film, and the liquid crystal Molecular orientation and the like can be improved. It is preferable that the compound has compatibility with the liquid crystal molecules and can change the tilt angle of the liquid crystal molecules or does not inhibit the alignment.
Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer and is preferably copolymerizable with the polymerizable group-containing liquid crystal compound. Examples thereof include those described in paragraph numbers [0018] to [0020] in JP-A No. 2002-296423. The amount of the compound added is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the discotic liquid crystalline molecules.

Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specific examples include compounds described in paragraph numbers [0028] to [0056] in JP-A-2001-330725.
The polymer used together with the discotic liquid crystalline molecule is preferably capable of changing the tilt angle of the discotic liquid crystalline molecule.
A cellulose ester can be mentioned as an example of a polymer. Preferable examples of the cellulose ester include those described in paragraph [0178] of JP-A No. 2000-155216. The addition amount of the polymer is preferably in the range of 0.1 to 10% by mass, and preferably in the range of 0.1 to 8% by mass with respect to the liquid crystal molecule so as not to disturb the alignment of the liquid crystal molecules. It is more preferable. The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline molecules is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

(B-5) Formation of optically anisotropic layer The optically anisotropic layer is coated with a coating liquid containing liquid crystalline molecules and, if necessary, a polymerizable initiator and an optional component described later on the alignment film. Can be formed.
As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, , Chloroform, dichloromethane, tetrachloroethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

The coating liquid can be applied by a known method (eg, wire bar coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method).
The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and most preferably 1 to 10 μm.

(B-6) Fixing of alignment state of liquid crystalline molecules The aligned liquid crystalline molecules can be fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred.
Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin. Compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,212,970).
The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution.
It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules.
The irradiation energy is preferably in the range of ^{20mJ / cm 2 ~50J / cm 2} , more preferably in the range of 20~5000mJ / cm ^2, more preferably in the range of 100 to 800 mJ / cm ² . In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.
A protective layer may be provided on the optically anisotropic layer.

It is also preferable to combine this optical compensation film and a polarizing layer (polarizing plate). Specifically, the optically anisotropic layer is formed by applying the coating liquid for the optically anisotropic layer as described above to the surface of the polarizing film. As a result, without using a polymer film between the polarizing film and the optically anisotropic layer, a thin polarizing plate having a small stress (strain × cross-sectional area × elastic modulus) associated with the dimensional change of the polarizing film is produced. . When the polarizing plate according to the present invention is attached to a large liquid crystal display device, an image with high display quality can be displayed without causing problems such as light leakage.
The tilt angle between the polarizing layer and the optical compensation layer is stretched so as to match the angle formed between the transmission axis of the two polarizing plates bonded to both sides of the liquid crystal cell constituting the LCD and the vertical or horizontal direction of the liquid crystal cell. Is preferred. A normal inclination angle is 45 °. Recently, however, devices that are not necessarily 45 ° have been developed for transmissive, reflective, and transflective LCDs, and it is preferable that the stretching direction can be arbitrarily adjusted in accordance with the design of the LCD.

(C) Application of an antireflection layer (antireflection film)
The antireflection film of the present invention is characterized by using the thermoplastic film of the present invention. Usually, the thermoplastic film of the present invention is used as a base material and an antireflection film is provided thereon.
The antireflection film generally includes a low refractive index layer which is also an antifouling layer, and at least one layer having a higher refractive index than that of the low refractive index layer (that is, a high refractive index layer and a medium refractive index layer). It is provided above.

Colloidal metal by multilayer deposition of transparent thin films of inorganic compounds (metal oxides, etc.) with different refractive indexes by chemical vapor deposition (CVD) method, physical vapor deposition (PVD) method, sol-gel method of metal compounds such as metal alkoxides Examples include a method of forming a thin film by post-processing (ultraviolet irradiation: JP-A-9-157855, plasma processing: JP-A-2002-327310) after forming an oxide particle film.
On the other hand, various antireflection films formed by laminating thin films in which inorganic particles are dispersed in a matrix have been proposed as antireflection films with high productivity.
The antireflection film which consists of the antireflection layer which provided the anti-glare property which the antireflection film by application | coating as mentioned above provided the surface of the uppermost layer with the shape of a fine unevenness | corrugation is mentioned.
The thermoplastic film of the present invention can be applied to any of the above methods, but a coating method (coating type) is particularly preferable.

(C-1) Layer configuration of coating type antireflection film An antireflection film comprising a layer configuration in the order of at least a medium refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) on a substrate is as follows. Designed to have a refractive index that satisfies the relationship.
Refractive index of high refractive index layer> refractive index of medium refractive index layer> refractive index of transparent support> refractive index of low refractive index layer

Further, a hard coat layer may be provided between the transparent support and the medium refractive index layer. Furthermore, it may consist of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer.
Examples thereof include JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706, and the like. Other functions may be imparted to each layer, for example, an antifouling low refractive index layer or an antistatic high refractive index layer (eg, JP-A-10-206603, JP-A-2002). -243906 publication etc.) etc. are mentioned.

  The haze of the antireflection film is preferably 5% or less, more preferably 3% or less. The strength of the film is preferably H or higher, more preferably 2H or higher, and most preferably 3H or higher in a pencil hardness test according to JIS K5400.

(C-2) High Refractive Index Layer and Medium Refractive Index Layer The antireflective layer having a high refractive index is a curable film containing at least inorganic compound ultrafine particles having a high refractive index with an average particle size of 100 nm or less and a matrix binder. Consists of.
Examples of the high refractive index inorganic compound fine particles include inorganic compounds having a refractive index of 1.65 or more, preferably those having a refractive index of 1.9 or more. Examples thereof include oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and composite oxides containing these metal atoms.
In order to obtain such ultrafine particles, the surface of the particles is treated with a surface treatment agent (for example, silane coupling agents, etc .: JP-A-11-295503, JP-A-11-153703, JP-A-2000-9908). , Anionic compounds or organometallic coupling agents: JP 2001-310432 A, etc., core-shell structure with high refractive index particles as the core (JP 2001-166104 A, etc.), specific dispersant combined use (E.g., Japanese Patent Laid-Open No. 11-153703, Japanese Patent No. US6210858B1, Japanese Patent Laid-Open No. 2002-27776069, etc.).

Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.
Further, it is selected from a polyfunctional compound-containing composition containing at least two radically polymerizable and / or cationically polymerizable groups, an organometallic compound containing a hydrolyzable group, and a partial condensate composition thereof. At least one composition is preferred. Examples thereof include compounds described in JP-A Nos. 2000-47004, 2001-315242, 2001-31871, and 2001-296401.
A curable film obtained from a colloidal metal oxide obtained from a hydrolyzed condensate of metal alkoxide and a metal alkoxide composition is also preferred. For example, it describes in Unexamined-Japanese-Patent No. 2001-293818.

The refractive index of the high refractive index layer is generally 1.70 to 2.20. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.
The refractive index of the middle refractive index layer is adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.50 to 1.70.

(C-3) Low refractive index layer The low refractive index layer is formed by sequentially laminating on the high refractive index layer. The refractive index of the low refractive index layer is 1.20 to 1.55. Preferably it is 1.30-1.50.
It is preferable to construct as the outermost layer having scratch resistance and antifouling property. As means for greatly improving the scratch resistance, imparting slipperiness to the surface is effective, and conventionally known thin film layer means such as introduction of a silicone compound or introduction of fluorine by a fluorine-containing compound can be applied.

The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50. More preferably, it is 1.36-1.47. The fluorine-containing compound is preferably a compound containing a crosslinkable or polymerizable functional group containing fluorine atoms in the range of 35 to 80% by mass.
For example, paragraph numbers [0018] to [0026] of Japanese Patent Application Laid-Open No. 9-222503, paragraph numbers [0019] to [0030] of Japanese Patent Application Laid-Open No. 11-38202, and paragraph numbers of Japanese Patent Application Laid-Open No. 2001-40284. [0027] to [0028], JP-A 2000-284102, and the like.

The silicone compound is a compound having a polysiloxane structure, preferably containing a curable functional group or a polymerizable functional group in the polymer chain and having a crosslinked structure in the film. For example, reactive silicone (eg, Silaplane (manufactured by Chisso Corporation), silanol group-containing polysiloxane (Japanese Patent Laid-Open No. 11-258403, etc.) and the like can be mentioned.
The crosslinking or polymerization reaction of the fluorine-containing and / or siloxane polymer having a crosslinking or polymerizable group is carried out at the same time or after the coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer, etc. It is preferable to carry out by light irradiation or heating.

Also preferred is a sol-gel cured film in which an organometallic compound such as a silane coupling agent and a specific fluorine-containing hydrocarbon group-containing silane coupling agent are cured by a condensation reaction in the presence of a catalyst.
For example, a polyfluoroalkyl group-containing silane compound or a partially hydrolyzed condensate thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, Japanese Patent Laid-Open Nos. 9-157582, 11) -106704), silyl compounds containing a poly "perfluoroalkyl ether" group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open Nos. 2000-117902, 2001-48590, 2002) 53804), and the like.

The low refractive index layer has an average primary particle diameter of 1 to 150 nm such as a filler (for example, silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride)) as an additive other than the above. Low refractive index inorganic compounds, organic fine particles described in paragraphs [0020] to [0038] of JP-A-11-3820, etc.), silane coupling agents, slip agents, surfactants, and the like can be contained.
When the low refractive index layer is located below the outermost layer, the low refractive index layer may be formed by a vapor phase method (vacuum deposition method, sputtering method, ion plating method, plasma CVD method, etc.). The coating method is preferable because it can be manufactured at a low cost.
The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and most preferably 60 to 120 nm.

(Her 4) Hard coat layer The hard coat layer is provided on the surface of the transparent support in order to impart physical strength to the antireflection film. In particular, it is preferably provided between the transparent support and the high refractive index layer.
The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound. As the curable functional group, a photopolymerizable functional group is preferable, and the organometallic compound containing a hydrolyzable functional group is preferably an organic alkoxysilyl compound.
Specific examples of these compounds are the same as those exemplified for the high refractive index layer.
Specific examples of the constituent composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and International Publication WO0 / 46617.
The high refractive index layer can also serve as a hard coat layer. In such a case, it is preferable to form fine particles dispersed in the hard coat layer using the method described for the high refractive index layer.

The hard coat layer can also serve as an antiglare layer (described later) provided with particles having an average particle size of 0.2 to 10 μm to provide an antiglare function (antiglare function).
The film thickness of the hard coat layer can be appropriately designed depending on the application. The film thickness of the hard coat layer is preferably 0.2 to 10 μm, more preferably 0.5 to 7 μm.
The strength of the hard coat layer is preferably H or higher, more preferably 2H or higher, and most preferably 3H or higher in a pencil hardness test according to JIS K5400. Further, in the Taber test according to JIS K5400, the smaller the wear amount of the test piece before and after the test, the better.

(C-5) Forward scattering layer The forward scattering layer is provided in order to give a viewing angle improvement effect when the viewing angle is inclined in the vertical and horizontal directions when applied to a liquid crystal display device. By dispersing fine particles having different refractive indexes in the hard coat layer, it can also serve as a hard coat function.
For example, Japanese Patent Application Laid-Open No. 11-38208 specifying a forward scattering coefficient, Japanese Patent Application Laid-Open No. 2000-199809 having a relative refractive index of a transparent resin and fine particles in a specific range, and Japanese Patent Application Laid-Open No. 2002 specifying a haze value of 40% or more. -107512 gazette etc. are mentioned.

(C-6) Other layers In addition to the above layers, a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like may be provided.

(C-7) Coating method Each layer of the antireflection film is formed by a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating, a micro gravure method or an extrusion coating method (US patent). No. 2,681,294) can be formed by coating.

(C-8) Anti-glare function The antireflection film may have an anti-glare function that scatters external light. The antiglare function is obtained by forming irregularities on the surface of the antireflection film. When the antireflection film has an antiglare function, the haze of the antireflection film is preferably 3 to 30%, more preferably 5 to 20%, and most preferably 7 to 20%.

  As a method for forming irregularities on the surface of the antireflection film, any method can be applied as long as these surface shapes can be sufficiently maintained. For example, a method of forming irregularities on the film surface using fine particles in the low refractive index layer (for example, JP 2000-271878 A), a lower layer of the low refractive index layer (high refractive index layer, medium refractive index layer) Alternatively, a small amount (0.1 to 50% by mass) of relatively large particles (particle size 0.05 to 2 μm) is added to the hard coat layer to form a surface uneven film, and these shapes are maintained thereon. A method of providing a low refractive index layer (for example, JP-A-2000-281410, 2000-95893, 2001-100004, 2001-281407, etc.), uppermost layer (antifouling layer) And a method of physically transferring the uneven shape onto the surface after coating (for example, as an embossing method, Japanese Patent Laid-Open Nos. 63-278839, 11-183710, 2000-275401) It includes equal forth) and the like.

(D) Liquid crystal display device The liquid crystal display device of the present invention can use a polarizing plate, an optical compensation sheet, an antireflection film or the like using the thermoplastic film of the present invention as described above, instead of a known one. . Each liquid crystal mode of the liquid crystal display layer of the present invention will be described.

(TN mode liquid crystal display)
The TN mode liquid crystal display device is most frequently used as a color TFT liquid crystal display device, and is described in many documents. The alignment state in the liquid crystal cell in the TN mode black display is an alignment state in which the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie in the vicinity of the cell substrate.

(OCB mode liquid crystal display)
The OCB mode liquid crystal display device is a bend alignment mode liquid crystal cell in which rod-like liquid crystal molecules are aligned (symmetrically) in substantially opposite directions at the upper and lower portions of the liquid crystal cell. Liquid crystal display devices using a bend alignment mode liquid crystal cell are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. Therefore, this liquid crystal mode is OCB (Optically Compensatory Bend).
Also called liquid crystal mode.
Similarly to the TN mode, the liquid crystal cell in the OCB mode is in a black display, and the alignment state in the liquid crystal cell is such that the rod-like liquid crystal molecules rise in the center of the cell and the rod-like liquid crystal molecules lie in the vicinity of the cell substrate. .

(VA mode liquid crystal display device)
The VA mode liquid crystal display device is characterized in that the rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied. (1) No voltage is applied to the VA mode liquid crystal cell. In addition to a narrowly-defined VA mode liquid crystal cell (described in JP-A-2-176625), which is sometimes aligned substantially vertically and aligned substantially horizontally when a voltage is applied, Liquid crystal cell with multi-domain mode (MVA mode) (described in SID97, Digest of tech. Papers 28 (1997) 845), (3) Substantially vertical alignment of rod-like liquid crystalline molecules when no voltage is applied (N-ASM mode) liquid crystal cell (described in the proceedings 58-59 (1998) of the Japanese Liquid Crystal Society) and (4 The liquid crystal cell of SURVAIVAL mode (published in LCD International 98) are included.

(IPS mode liquid crystal display)
The IPS mode liquid crystal display device is characterized in that rod-like liquid crystalline molecules are substantially aligned horizontally in a plane when no voltage is applied, and this is switched by changing the alignment direction of the liquid crystal with or without voltage application. Is the feature. Specifically, JP 2004-365951 A, JP 2004-12731 A, JP 2004-215620 A, JP 2002-221726 A, JP 2002-55341 A, JP 2003-195333 A. Those described in the publication can be used.

(Other liquid crystal display devices)
The ECB mode and the STN mode can be optically compensated in the same way as described above.

It should be noted that the present invention and the techniques disclosed in the following patent publications can be used in combination without departing from the spirit of the present invention.
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  The measurement method used in the present invention is described below.

(1) Degree of stretching during cooling from Tg + 40 ° C. to Tg (i) Temperature measurement The temperature change between the die and the CD is continuously measured using a non-contact thermometer (for example, a radiation thermometer). Reveal the temperature at a specific location between CDs.
(Ii) Measurement of the degree of stretching in the film forming direction The melt resin is marked at 0.5 second intervals at the die exit, and these are fixed points provided in the film forming direction. The extent to which the mark interval is extended from the die position to the casting drum is measured by photography. Further, the mark interval at the time of cooling to 25 ° C. is also measured.
(Iii) Calculation of degree of stretching
The distance between the marks at the position of Tg + 40 ° C. obtained in (i) and the distance between the marks at the position of Tg are obtained. Further, the degree of stretching is calculated according to the above formula (A) together with the data on the distance between marks at 25 ° C.

(2) Die exit melt viscosity
(i) Die exit temperature measurement The die exit temperature is measured at the center in the width direction (denoted t).
(ii) Melt viscosity measurement The melt viscosity of a thermoplastic resin is measured under the following conditions using a viscoelasticity measuring device using a parallel cone (for example, modular compact rheometer manufactured by Anton Paar: Physica MCR301).
Next, after the resin is sufficiently dried to make the water content 0.1% or less, the melt viscosity is measured at a gap of 500 μm, a frequency of 1 Hz, a strain of 1%, and a temperature of t ° C.

(3) Re, Rth
First, each retardation in the present invention will be described. In this specification, Re and Rth (unit: nm) are determined according to the following method. First, the film was conditioned at 25 ° C. and 60% relative humidity for 24 hours, and then a prism coupler (MODEL2010 Prism Coupler: manufactured by Metricon) was used. At 25 ° C. and 60% relative humidity, the following formula was used: An average refractive index (n) represented by (a) is obtained.
Formula (a): n = (n _TE × 2 + n _TM ) / 3
[ _Where n _TE is a refractive index measured with polarized light in the film plane direction, and n _TM is a refractive index measured with polarized light in the film surface normal direction. ]

In the present specification, Re (λ) and Rth (λ) each represent in-plane retardation and retardation in the thickness direction at a wavelength λ. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments).
When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.

Rth (λ) is Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis) (in the absence of the slow axis, any in-plane value) Measurements were made at 11 points in total by making light of wavelength λ nm incident from each inclined direction in steps of 10 ° from −50 ° to + 50 ° from the normal direction to the normal direction of the film). Then, KOBRA 21ADH or WR is calculated based on the measured retardation value, average refractive index, and input film thickness value.
In the above, there is no particular description regarding λ, and when only Re and Rth are described, it represents a value measured using light with a wavelength of 590 nm. In addition, in the case of a film having a retardation value of zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, the retardation value at a tilt angle larger than that tilt angle. After changing its sign to negative, KOBRA 21ADH or WR calculates.

  In addition, the retardation value is measured from the two inclined directions, with the slow axis as the tilt axis (rotation axis) (when there is no slow axis, the arbitrary direction in the film plane is the rotation axis), Based on the value, the average refractive index, and the input film thickness value, Rth can also be calculated from the following formulas (b) and (c).

［式中、Ｒｅ（θ）は法線方向から角度θ傾斜した方向におけるレタ−デーション値をあらわす。また、ｎｘは面内における遅相軸方向の屈折率を表し、ｎｙは面内においてｎｘに直交する方向の屈折率を表し、ｎｚはｎｘおよびｎｙに直交する方向の屈折率を表す。］

[In the formula, Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. Further, nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction perpendicular to nx in the plane, and nz represents the refractive index in the direction perpendicular to nx and ny. ]

Formula (c): Rth = ((nx + ny) / 2−nz) × d

When the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film having no so-called optical axis, Rth (λ) is calculated by the following method.
Rth (λ) is Re (λ), and the in-plane slow axis (determined by KOBRA 21ADH or WR) is the tilt axis (rotation axis) from −50 ° to + 50 ° with respect to the film normal direction. Measured at 11 points by injecting light of wavelength λ nm from each inclined direction in 10 ° steps, and KOBRA 21ADH or WR is calculated based on the measured retardation value, average refractive index, and input film thickness value. To do.
By inputting these average refractive index and film thickness, KOBRA 21ADH or WR calculates nx, ny, and nz. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

(4) Degree of substitution of cellulose acylate resin The degree of acyl substitution of cellulose acylate resin is determined according to Carbohydr. Res. 273 (1995) 83-91 may be determined by ¹³ C-NMR according to the method described in (Tezuka et al.).

(5) Residual solvent amount A sample film of 300 mg dissolved in 30 ml of methyl acetate (sample A) and a sample film dissolved in 30 ml of dichloromethane (sample B) are prepared. Subsequently, these are measured under the following conditions using gas chromatography (GC).
Column: DB-WAX (0.25 mmφ × 30 m, film thickness 0.25 μm)
Column temperature: 50 ° C
Carrier gas: Nitrogen Analysis time: 15 minutes Sample injection volume: 1 μml

The amount of solvent can be determined by the following method.
For each peak of sample A other than the solvent (methyl acetate), the content is determined using a calibration curve, and the sum is defined as Sa. In sample B, the content rate is determined using a calibration curve for each peak in the region hidden by the solvent peak in sample A, the sum is Sb, and the sum of Sa and Sb is the residual solvent amount.

(6) Elastic modulus
(i) Sampling Samples of 1 cm x 15 cm from the center and both ends (40% of the total width from the center) of the sample film in the MD direction and TD direction, respectively (3 sheets of MD, 9 sheets of TD, 18 sheets in total) Cut out.
(ii) Measurement of elastic modulus After conditioning these samples for 5 hours or more at 25 ° C. and 60% relative humidity, a tensile test was conducted at a tensile rate of 10 mm / min with 10 cm between chucks, and the elastic modulus was measured. Was the elastic modulus.

(7) Foreign matter
(i) Sampling 20 points are sampled at equal intervals over the entire width of the film.
(ii) Foreign matter measurement The number of foreign matters having a magnification of 50 and at least one side of 10 μm or more was counted and converted to the number per 1 cm ² . This was measured for 10 visual fields per sample, and the average was obtained (A value). This was measured for each sample, and the average of each A value was taken as the number of foreign matters.

(8) Dimensional stability Two holes having a diameter of 8 mm were formed in a sample cut to 5 cm × 25 cm at intervals of 200 mm, and the humidity was adjusted for 24 hours in an atmosphere of 25 ° C. and a relative humidity of 60%. Thereafter, the distance between the two holes was measured with an accuracy of 1/1000 mm using a pin gauge. This length is Xmm. Next, the sample was placed in a 60 ° C. air constant temperature bath without applying tension, and allowed to stand for 500 hours, then transferred to an atmosphere of 25 ° C. and a relative humidity of 60% and humidity-controlled for 24 hours, and the interval (Ymm) between two holes was measured in the same manner. . The dimensional change was calculated | required with the following formula | equation.
Dimensional change rate = {(XY) / 200} × 100 (% /% RH)
This operation was also measured on a sample rotated by 60 ° from the MD direction, and the average value was defined as the dimensional change rate in all directions.

  Although the specific embodiment about the thermoplastic film of this invention is described below, it is not limited to these.

[Example A]
In Example A, a cellulose acylate resin was used as the thermoplastic resin.
1. Cellulose acylate film (1) Cellulose acylate resin
(i) Synthesis of cellulose acetate propionate (CAP) 150 parts by mass of cellulose (hardwood pulp) and 75 parts by mass of acetic acid were placed in a reaction vessel equipped with a reflux apparatus and vigorously stirred while heating to 60 ° C. Samples were prepared by changing the number of foreign matters derived from unreacted cellulose by changing the pretreatment time. The cellulose subjected to such pretreatment swelled and crushed to form a fluff shape. The reaction vessel was placed in an ice water bath at 2 ° C. for 30 minutes and cooled.
Separately, a mixture of 1410 parts by mass of propionic anhydride and 10.5 parts by mass of sulfuric acid was prepared as an acylating agent, cooled to −30 ° C., and then put into a reaction vessel containing the pretreated cellulose at once. added. After 30 minutes, the external temperature was gradually increased, and the internal temperature was adjusted to 25 ° C. after 2 hours from the addition of the acylating agent. The reaction vessel was cooled in an ice water bath at 5 ° C., the internal temperature was adjusted to 10 ° C. 0.5 hours after addition of the acylating agent, and the internal temperature was 23 ° C. after 2 hours, and the internal temperature was 23 ° C. The mixture was further stirred for 3 hours. The reaction vessel was cooled in an ice water bath at 5 ° C., and 120 parts by mass of 25% by mass hydrous acetic acid cooled to 5 ° C. was added over 1 hour. The internal temperature was raised to 40 ° C. and stirred for 2 hours (aging). Next, a solution obtained by dissolving magnesium acetate tetrahydrate in 2-fold mol of sulfuric acid in 50% by mass aqueous acetic acid was added to the reaction vessel, and the mixture was stirred for 30 minutes. 25 parts by mass of hydrous acetic acid 1000 parts by mass, 33% by mass hydrous acetic acid 500 parts by mass, 50% by mass hydrous acetic acid 1000 parts by mass and water 1000 parts by mass were added in this order to precipitate cellulose acetate propionate. The obtained cellulose acetate propionate precipitate was washed with warm water. After washing, the mixture was stirred in a 0.005 mass% calcium hydroxide aqueous solution at 20 ° C. for 0.5 hour, further washed with water until the pH of the washing solution became 7, and then vacuum dried at 70 ° C.

  According to NMR and GPC measurements, the obtained cellulose acetate propionate had an acetyl (Ac) degree of 0.45, a propionyl (Pr) degree of 2.45, and a degree of polymerization of 160. The composition was measured by the NMR method described above, and the degree of polymerization was measured using GPC as follows.

-Number average molecular weight (Mn) was determined using THF as an eluent and monodisperse polystyrene as a standard molecular weight.
-The molecular weight (m) per segment was determined from the composition determined by NMR.
-Mn was divided by m to determine the degree of polymerization (number average degree of polymerization: DPn).

(ii) Synthesis of Cellulose Acetate Butyrate (CAB) 100 parts by mass of cellulose (cotton linter) and 135 parts by mass of acetic acid were placed in a reaction vessel equipped with a reflux apparatus and stirred vigorously while heating to 60 ° C. Samples were prepared by changing the number of foreign matters derived from unreacted cellulose by changing the pretreatment time. The cellulose subjected to such pretreatment swelled and crushed to form a fluff shape. The reaction vessel was placed in an ice water bath at 5 ° C. for 60 minutes and cooled.
Separately, a mixture of 1080 parts by weight of butyric anhydride and 10.0 parts by weight of sulfuric acid was prepared as an acylating agent, cooled to −20 ° C., and then added to a reaction vessel containing pretreated cellulose at once. After 30 minutes, the external temperature was raised to 20 ° C. and reacted for 5 hours. The reaction vessel was cooled in an ice water bath at 5 ° C., and 2400 parts by mass of 12.5 mass% hydrous acetic acid cooled to about 5 ° C. was added over 1 hour. The internal temperature was raised to 30 ° C. and stirred for 1.5 hours (aging). Subsequently, 100 mass parts of 50 mass% aqueous solution of magnesium acetate tetrahydrate was added to the reaction container, and it stirred for 30 minutes. 1000 parts by mass of acetic acid and 2500 parts by mass of 50% by mass hydrous acetic acid were gradually added to precipitate cellulose acetate butyrate. The obtained cellulose acetate butyrate precipitate was washed with warm water. After washing, the mixture was stirred in a 0.005 mass% calcium hydroxide aqueous solution for 0.5 hour, further washed with water until the pH of the washing solution became 7, and then dried at 70 ° C. The obtained cellulose acetate butyrate had an acetyl (Ac) degree of 0.84, a butyryl (Bu) degree of 2.12, and a degree of polymerization of 180.
(Iii) Synthesis of other cellulose acylates The degree of substitution is changed by changing the type and amount of acylating agent, the number of bright spots is changed by changing the pretreatment time, and the polymerization degree is changed by changing the aging time. Cellulose acylates other than CAP and CAB listed in Table 1 were synthesized.
In addition, cellulose acylate esterified with benzoic acid and acetic acid was synthesized as cellulose acylate having a substituted or unsubstituted aromatic acyl group bonded thereto in accordance with Example 1 of JP-A No. 2002-3201. However, as the raw material cellulose acylate, 2.0-substituted and 2.45-substituted cellulose acetates were used, respectively. As a result, an aromatic acyl group-substituted cellulose acylate having an acetic acid substitution degree = 2.0 and a benzoic acid substitution degree = 1.0, and an acetic acid substitution degree = 2.45 and an benzoic acid substitution degree = 0.55 aromatic Acyl group-substituted cellulose acylate was obtained (Examples 44 and 45).
In addition to this, cellulose acylate having an aromatic acyl group bonded thereto in Examples 2 to 7 of JP-A No. 2002-3201 was synthesized and formed in the same manner as Examples 44 and 45 in Table 1, respectively. The stretched films 11 to 15 were stretched under the same conditions, but all obtained good results in the same manner as the above-described cellulose acylate substituted with benzoic acid.
Further, cellulose acetate propionate having an acetyl substitution degree of 1.8, a propionyl substitution degree of 0.8, and a number average polymerization degree of 230 was synthesized according to the above-described method, and described in the examples of JP-A-2006-195407. A plasticizer of Example 47 was added.

(2) Melt film formation
(i) Pelletization of cellulose acylate 100 parts by mass of the above cellulose acylate, 0.3 parts by mass of stabilizer (Sumilizer GP manufactured by Sumitomo Chemical Co., Ltd.), 0.05 parts by mass of silicon dioxide part particles (Aerosil R972V), ultraviolet rays Absorber (2- (2′-hydroxy-3 ′, 5-di-tert-butylphenyl) -benzotriazole 0.05 parts by weight, 2,4-hydroxy-4-methoxy-benzophenone 0.1 parts by weight). Mixed.
These were dried at 100 ° C. for 3 hours to reduce the water content to 0.1% by mass or less, melted at 180 ° C. using a twin-screw kneader, then extruded into warm water at 60 ° C., and then cut into diameters. It was molded into a cylindrical pellet 3 mm long and 5 mm long.

(ii) Melt Film Formation The cellulose acylate pellets prepared by the above method were dried at 100 ° C. for 5 hours using dehumidified air having a dew point temperature of −40 ° C. to make the water content 0.01% by mass or less. This was put into a hopper at 80 ° C. and melted with a melt extruder adjusted from 180 ° C. (inlet temperature) to 230 ° C. (outlet temperature). In addition, the diameter of the screw used for this was 60 mm, L / D = 50, and the compression ratio was 4. The resin extruded from the melt extruder is weighed and sent out by a gear pump. At this time, the number of revolutions of the extruder is changed so that the resin pressure before the gear pump can be controlled at a constant pressure of 10 MPa. The melt resin delivered from the gear pump was filtered through a leaf disk filter having a filtration accuracy of 5 μm, and extruded from a hanger coat die with a slit interval of 0.8 mm via a static mixer.

Stretching was performed until the extruded resin was cooled to Tg + 40 ° C., and the thickness at Tg + 40 ° C. was adjusted to the thickness shown in Table 1 below. Thereafter, the resin was rapidly cooled by being directly placed on the casting drum set to the resin temperature Tg, and the temperature was lowered to the resin temperature Tg or less. When using the touch roll, the unstretched film was brought into contact with the touch roll under the conditions described in Table 1 on the most upstream cast roll. The touch roll was the one described in Example 1 of JP-A-11-235747 (the one described as a double holding roll), and the temperature was adjusted to Tg-5 ° C. (however, the thickness of the thin metal outer cylinder was 3 mm).
The solidified melt is peeled off from the casting drum, both ends (5% each of the total width) are trimmed immediately before winding, and then 10 mm wide and 50 μm high thickness processing (knurling) is applied to both ends, and then 30 m / min. Thus, an unstretched film having a width of 1.5 m and a length of 3000 m was obtained.

  The Tg of the thermoplastic resin was measured by the following method using DSC.

(Tg measurement)
20 mg of a sample was placed in a DSC measurement pan. This is heated from 30 ° C. to 250 ° C. at 10 ° C./min in a nitrogen stream (1st-run), and then cooled to 30 ° C. at −10 ° C./min. Thereafter, the temperature is raised again from 30 ° C. to 250 ° C. (2nd-run). The glass transition temperature (Tg) was defined as the temperature at which the baseline began to deviate from the low temperature side at 2nd-run.

  When the residual solvent amount of these films was measured, the residual solvent was not measured.

(3) Production of polarizing plate (3-1)
The cellulose acylate film after stretching was saponified by the following dipping method. Although the following coating saponification was also performed, the same results as in the immersion saponification were obtained.

(i) Immersion saponification A 1.5 N aqueous solution of NaOH was used as a saponification solution.
The temperature was adjusted to 60 ° C., and the cellulose acylate film was immersed for 2 minutes.
Thereafter, it was immersed in a 0.1N aqueous sulfuric acid solution for 30 seconds and then passed through a water-washing bath.

(ii) Coating saponification 20 parts by mass of water was added to 80 parts by mass of isopropanol, and KOH was dissolved in this to 1.5 N, and this was adjusted to 60 ° C. and used as a saponification solution.
This was coated on a cellulose acylate film at 60 ° C. at 10 g / m ² and saponified for 1 minute. Thereafter, hot water at 50 ° C. was sprayed at 10 l / m ² · min for 1 minute for cleaning.

(3-2) Production of Polarizing Layer According to Example 1 of Japanese Patent Application Laid-Open No. 2001-141926, a circumferential speed difference was given between two pairs of nip rolls, and a polarizing layer having a thickness of 20 μm was prepared by stretching in the longitudinal direction.

(3-3) Peeling / warping Ten samples were prepared by cutting the polarizing plate thus prepared into strips having a width of 1 cm and a length of 20 cm. This sample was stored at 60 ° C. under dry conditions for 500 hours, and it was confirmed how many of the 10 sheets were peeled off. Similarly, the thermal test was performed to determine the warpage size, how many centimeters were warped in each of the 10 samples, and the average of 10 was taken as the warpage size.
Table 1 shows the test results in the steps (1) to (3).

  Good performance was obtained with the present invention. On the other hand, it can be seen that in the samples (Comparative Examples 1 and 2) in which the degree of stretching was out of the range of the present invention, residual distortion was present in the cellulose acylate film, and thus warpage and peeling occurred more than other samples. In particular, the present invention is greatly improved in both warpage and peeling as compared with the unstretched film of Sample 3-2 of Example 1 described in JP-A-2000-352620 (Comparative Example 3 in Table 1). It was. Furthermore, what performed this invention on the conditions close | similar to this (Example 38 of Table 1) acquired the favorable performance.

(4) Production / Evaluation of Stretched Film The unstretched sheets of Invention 26 and Inventions 40 and 42 in Table 1 above were subjected to the following magnifications (longitudinal stretch, lateral width) at 300% / min at the glass transition temperature (Tg + 10) ° C. The same conditions as for stretching) were stretched to obtain a film having the following Re and Rth. The draw ratio here is defined by the following formula.
Stretch ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / (Length before stretching)

In the above table, the Re and Rth fluctuations (variations) and the orientation angle in the width direction and the longitudinal direction were measured by the following methods.
(1) LD direction (longitudinal direction) sampling was cut into 100 cm and 1 cm square sizes at 0.5 m intervals in the longitudinal direction. The sampling in the TD direction (width direction) was cut out at equal intervals of 50 points in the size of 1 cm square over the entire width of film formation.
(2) Re and Rth were measured according to the above methods. The orientation angle was determined by setting and measuring the LD side of the sample film in parallel with the measuring instrument insertion direction of the sample holder when performing the above measurement.
(3) For Re and Rth fluctuations, the difference between the maximum value and the minimum value at 100 points in the LD direction and 50 points in the TD direction was divided by the respective average values, and the percentages indicated as percentages were designated as Re and Rth fluctuations. Regarding the orientation angle, the difference between the maximum value and the minimum value of the absolute value at each point was shown.

As for the dimensional change rate of these stretched films, those using the film-forming film of the present invention showed good performance at 10% or less. Further, the number of foreign matters was 25 pieces / cm ² or less, and the elastic modulus was 2.9 kN / mm ² or less.
Moreover, the thermal dimensional change rate of Table 2 and Table 4 was measured with the following method.
(1) The sample is cut into 5 cm × 25 cm in the LD and TD directions, and holes with an interval of 20 cm are formed.
(2) After adjusting the humidity at 25 ° C. and 60% relative humidity for 2 hours, the distance between the two holes is measured using a pin gauge in this environment (this is set as L1).
(3) Place the sample in an 80 ° C. air constant temperature bath for 5 hours.
(4) Take this out and adjust the humidity to 25 ° C. and 60% relative humidity for 3 hours, and then measure the distance between the two holes using a pin gauge in this environment (this is L2).
(5) Let 100 * (L1-L2) / L1 be a dimensional change rate (%).

The stretched cellulose acylate film thus obtained was saponified by the above-described method, and then a polarizing plate having the following composition was prepared as described above.
〔composition〕
Polarizing plate C: stretched cellulose acylate / polarizing layer / Fujitack (Fuji Photo Film Co., Ltd.)

  The polarizing plate thus obtained was attached in place of the polarizing plate of the 20-inch VA liquid crystal display device liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261. When warping and peeling were measured after 500 hours, all showed good performance. Similar results were obtained with films obtained by stretching the inventions 1 to 39.

(5) Production of optical compensation film The stretched cellulose acylate film of the present invention was used in place of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-11-316378. When the unevenness (light leakage) when this was moved from 30 ° C. to 10 ° C. by the same method as described above was measured, good performance was obtained in the case of carrying out the present invention.
In place of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-7-333433, the optically compensated filter film produced by changing to the stretched cellulose acylate film of the present invention is similarly good in optical compensation. A film could be produced.

(6) Production of low-reflection film A low-reflection film was produced using the stretched cellulose acylate film of the present invention in accordance with Example 47 of the Japan Institute of Invention and Technology (public technical number 2001-1745). Obtained.

(7) Production of Liquid Crystal Display Device The polarizing plate of the present invention is a liquid crystal display device described in Example 1 of JP-A-10-48420, and a discotic described in Example 1 of JP-A-9-26572. An optically anisotropic layer containing liquid crystal molecules, an alignment film coated with polyvinyl alcohol, a 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261, and JP-A-2000-154261 The 20-inch OCB type liquid crystal display device shown in FIGS. 10 to 15 and the IPS type liquid crystal display device shown in FIG. 11 of JP-A-2004-12731 were used. Furthermore, when the low reflection film of this invention was stuck and evaluated on the outermost layer of these liquid crystal display devices, the favorable liquid crystal display device was obtained.

[Example B]
In Example B, a saturated norbornene resin was used as the thermoplastic resin.
2. Saturated norbornene resin (1) Synthesis of saturated norbornene resin
(i) Saturated norvol resin A
6-methyl-1,4,5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 10 parts of a 15% cyclohexane solution of triethylaluminum as a polymerization catalyst, triethylamine 5 And 10 parts of a 20% cyclohexane solution of titanium tetrachloride were added to perform ring-opening polymerization in cyclohexane, and the resulting ring-opening polymer was hydrogenated with a nickel catalyst to obtain a polymer solution. This polymer solution was coagulated in isopropyl alcohol and dried to obtain a powdery resin (saturated norvol resin A). The number average molecular weight of this resin was 40,000, the hydrogenation rate was 99.8% or more, and the Tg was 139 ° C.

(ii) Saturated norvol resin B
100 parts of 8-methyl-8-methoxycarbonyltetracyclo [4.4.0.12.5, 17.10] -3-dodecene (specific monomer B) and 5- (4-biphenylcarbonyloxy) bicyclo [2.2.1] 150 parts of hept-2-ene (specific monomer A), 18 parts of 1-hexene (molecular weight regulator) and 750 parts of toluene were charged into a nitrogen-substituted reaction vessel, and this solution Was heated to 60 ° C. Next, 0.62 parts of a toluene solution of triethylaluminum (1.5 mol / l) as a polymerization catalyst and tungsten hexachloride modified with tert-butanol and methanol (tert-butanol: methanol: tungsten) were added to the solution in the reaction vessel. = 0.35 mol: 0.3 mol: 1 mol) of a toluene solution (concentration 0.05 mol / l) 3.7 parts was added, and the system was heated and stirred at 80 ° C. for 3 hours to open the ring. Polymerization reaction was performed to obtain a ring-opening polymer solution. The polymerization conversion rate in this polymerization reaction was 97%, and the intrinsic ring viscosity (ηinh) of the obtained ring-opened polymer measured in chloroform at 30 ° C. was 0.65 dl / g.

The autoclave was charged with 4,000 parts of the ring-opening polymer solution thus obtained, and 0.48 part of RuHCl (CO) [P (C ₆ H ₅ ) ₃ ] ₃ was added to the ring-opening polymer solution. Then, the hydrogenation reaction was performed by heating and stirring for 3 hours under the conditions of a hydrogen gas pressure of 100 kg / cm ² and a reaction temperature of 165 ° C. After cooling the obtained reaction solution (hydrogenated polymer solution), the hydrogen gas was released. This reaction solution was poured into a large amount of methanol to separate and recover a coagulated product, which was dried to obtain a hydrogenated polymer (specific cyclic polyolefin resin: saturated norbol resin B). The hydrogenated polymer thus obtained was measured for hydrogenation rate of olefinically unsaturated bonds using 400 MHz, ¹ H-NMR, and found to be 99.9%. When the number average molecular weight (Mn) and weight average molecular weight (Mw) in terms of polystyrene were measured by the GPC method (solvent: tetrahydrofuran), the number average molecular weight (Mn) was 39,000 and the weight average molecular weight (Mw) was 126,000. The molecular weight distribution (Mw / Mn) was 3.23. Moreover, Tg was 110 degreeC.

(iii) Saturated norvol resin C
As the saturated norborn resin C, a saturated norbornene compound (Tg 127 ° C.) described in Example 2 of JP-A-2005-330465 was used.
(iv) Saturated norvol resin D
As the saturated norborn resin D, the saturated norbornene compound (Tg 181 ° C.) described in Example 1 of JP-T-8-507800 was used.
(v) Saturated norvol resin E
As the saturated norbol resin E, APL6015T (Tg145 ° C.) manufactured by Mitsui Chemicals, Inc. was used.
(vi) Saturated norvol resin F
As the saturated norvol resin F, TOPAS6013 (Tg 130 ° C.) manufactured by Polyplastics Co., Ltd. was used.
(vii) Saturated norvol resin G
As the saturated norborn resin G, the saturated norbornene compound (Tg 140 ° C.) described in Example 1 of Japanese Patent No. 3693803 was used.

(2) Film formation The saturated norbornene resins A to G were formed into cylindrical pellets having a diameter of 3 mm and a length of 5 mm. This was dried with a vacuum dryer at 110 ° C., the water content was adjusted to 0.1% by mass or less, and charged into a hopper adjusted to Tg−10 ° C.
A T-die having a melt temperature adjusted to 1000 Pa · s, melted using a single-screw kneader at this temperature for 5 minutes, and then adjusted to the melt viscosity shown in Table 3 below. Extruded from. Thereafter, film formation was performed by the same method as (2) film formation in Example A (Examples 1 to 47). At this time, touch roll film formation was performed under the conditions described in Table 3 below. The solidified melt was peeled off and wound up. In addition, after trimming both ends (each 3% of the total width) just before winding, the both ends were subjected to thicknessing (knurling) with a width of 10 mm and a height of 50 μm. In each level, the width was 1.5 m, and 3000 m was wound at 30 m / min.

  No residual solvent was observed in the film thus formed. In addition, no foreign matter was observed.

(3) Preparation of polarizing plate (3-1) Surface treatment In any level, the film surface was subjected to corona treatment so that the contact angle with water on the surface was 60 °.

(3-2) Production of Polarizing Layer According to Example 1 of Japanese Patent Application Laid-Open No. 2001-141926, a circumferential speed difference was given between two pairs of nip rolls, and a polarizing layer having a thickness of 20 μm was prepared by stretching in the longitudinal direction.

(3-3) Bonding The following polarizing plate was produced in the same manner as in Example A described above.
Polarizing plate A: saturated norbornene film / polarizing layer / Fujitac

(3-4) Peeling / warping Ten samples were prepared by cutting the polarizing plate thus prepared into strips having a width of 1 cm and a length of 10 cm. This sample was stored at 60 ° C. under dry conditions for 500 hours, and it was confirmed how many of the 10 sheets were peeled off. Similarly, the thermal test was performed to determine the warpage size. In each of the 10 samples, the number of centimeters of warpage was measured, and the average of 10 was taken as the warpage size. ,

(4) Dimensional stability The dimensional change was measured by the same method as in Example A.
Table 3 shows the test results in the steps (1) to (3).

(8) Stretching The saturated norbornene film obtained by the melt film formation was stretched in the same manner as in Example A except for the conditions shown in Table 4 (stretching temperature: Tg + 10 ° C.). When this was incorporated into a liquid crystal display panel and evaluated in the same manner as in Example A, good performance was obtained.

(6) Production of optical compensation film An optical compensation film was produced in the same manner as in Example A described above. Good performance was obtained with the present invention.

(7) Production of low-reflection film A low-reflection film was produced in the same manner as in Example A described above, and good optical performance was obtained for the embodiment of the present invention.

(8) Production of liquid crystal display device A liquid crystal display device was produced in the same manner as in Example A described above. What implemented this invention was a favorable liquid crystal display device.

It is the schematic for demonstrating the relationship between the thickness of a melt, and temperature. The schematic block diagram of the film manufacturing apparatus which manufactures the thermoplastic film in the case of performing long span stretching is shown. FIG. 3 is a perspective explanatory view of a longitudinally extending portion in FIG. 2. The schematic block diagram of the film manufacturing apparatus which manufactures the thermoplastic film in the case of performing short span stretching is shown. The perspective explanatory view of the longitudinal extension part of Drawing 4 is shown. It is explanatory drawing of the bowing generate | occur | produced with the manufacturing method which does not heat-set. It is explanatory drawing which shows suppression of generation | occurrence | production of the bowing by heat setting. In melt film formation, the relationship between the temperature at which the thermoplastic resin discharged from the die is cooled and the Re and Rth of the resulting thermoplastic resin film is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Die exit 2 Position where target thickness is achieved A Temperature range more than Tg + 40 degreeC B Area | region cooled to temperature below Tg 10, 10a Film production apparatus 12 Dryer 14 Extruder 16 Gear pump 18 Filter 20 Die 22 Cooling part 24 Touch Roll 26 Touch Roll 28 Cast Drum 30, 30a Longitudinal Stretching Section 32 Entrance Side Nip Roll 33 Preheating Roll 34 Outlet Side Nip Roller 35 Preheating Roll 36 Preheating Section 37 Nip Roll 39 Nip Roll 42 Lateral Stretching Section 44 Heat Fixing Section 46 Winding Section Fa Stretched film Fb Longitudinal stretched film F Thermoplastic film Lb Curve

Claims (18)

A method for producing a thermoplastic film, in which a melted thermoplastic resin is formed through a step of discharging a die from a die onto a casting drum in a sheet form,
While the thermoplastic resin discharged in sheet form from the die is cooled from Tg + 40 ° C. to Tg ° C. (Tg is the glass transition temperature of the thermoplastic resin), the film formation represented by the following formula (A) A method for producing a thermoplastic film, wherein the thermoplastic resin is discharged onto a casting drum while controlling the degree of stretching in a direction to be 25% or less.

(In the above formula, T1 represents the distance between two fixed points on the film provided in the film forming direction when the thermoplastic resin is cooled to Tg + 40 ° C., and T2 is the temperature at which the thermoplastic resin is cooled to Tg ° C. (T0 represents the distance between the two fixed points at 25 ° C. of the formed thermoplastic resin.)   The method for producing a thermoplastic film according to claim 1, wherein the thermoplastic resin at the die outlet has a melt viscosity of 100 Pa · s to 2000 Pa · s.   The method for producing a thermoplastic film according to claim 1 or 2, wherein the thermoplastic resin is formed on the casting drum using a touch roll.   A thermoplastic film characterized by having a dimensional change in all directions of 1% or less when aged for 500 hours at 60 ° C.   The thermoplastic film according to claim 4, wherein the in-plane retardation (Re) is 0 nm to 25 nm and the thickness direction retardation (Rth) is 0 nm to 25 nm. 6. The thermoplastic film according to claim 4, comprising a cellulose acylate resin having a composition satisfying the following formulas (1) and (2).
Formula (1): 2.5 <= A + B <3.0
Formula (2): 1.25 ≦ B <3
(In the formula, A represents the degree of substitution of the acetate group, and B represents the sum of the degree of substitution of the propionate group, butyrate group, and pentanoyl group.) The thermoplastic film according to claim 4 or 5, comprising cellulose acylate having a composition satisfying the following formulas (T-1) and (T-2).
Formula (T-1): 2.5 <= A + C <3.0
Formula (T-2): 0.1 ≦ C <2
(In the formula, A represents the degree of substitution of the acetate group, and C represents a substituted or unsubstituted aromatic acyl group.)   The thermoplastic film according to claim 4 or 5, comprising a saturated norbornene resin.   The thermoplastic film according to any one of claims 4 to 8, which is produced by the method for producing a thermoplastic film according to any one of claims 1 to 3.   The thermoplastic film according to any one of claims 4 to 9, wherein the residual solvent amount is 0.01% by mass or less. The drawing treatment is performed, and in-plane retardation (Re) and thickness direction retardation (Rth) satisfy the following (3) and (4): Thermoplastic film.
Formula (3): 0 nm ≦ Re ≦ 150 nm
Formula (4): 0 nm ≦ Rth ≦ 300 nm  A thermoplastic film obtained by stretching the thermoplastic film according to any one of claims 4 to 11 at an aspect ratio L / W of more than 2 and 50 or less, or 0.01 to 0.3.  The thermoplastic film according to any one of claims 4 to 12, wherein the thermoplastic film is preheated at a temperature higher by 1 ° C to 50 ° C than the stretching temperature before transverse stretching.  The thermoplastic film according to any one of claims 4 to 13, wherein the thermoplastic film is heat-treated at a temperature lower by 1 to 50 ° C than the stretching temperature after transverse stretching.  The thermoplastic film according to any one of claims 4 to 14, after the transverse stretching or longitudinal stretching, at (Tg-50) ° C to (Tg + 30) ° C, 0.1 kg / A thermoplastic film characterized by heat relaxation while being conveyed with a tension of m to 20 kg / m.   A polarizing plate, an optical compensation film, or an antireflection film, wherein at least one layer of the thermoplastic film according to any one of claims 4 to 15 is laminated on a polarizer.   A liquid crystal display device using at least one of the thermoplastic film according to any one of claims 4 to 15, the polarizing plate according to claim 16, an optical compensation film, and an antireflection film. A method for producing a thermoplastic film in which a molten thermoplastic resin is discharged from a die onto a casting drum to form a film,
During the stretching step of stretching the thermoplastic resin discharged from the die, and while the thermoplastic resin is cooled from Tg + 40 ° C. to Tg ° C. (Tg is the glass transition temperature of the thermoplastic resin), the following formula ( A method for producing a thermoplastic film, comprising: a stretching degree control step for controlling the stretching degree in the film forming direction indicated by A) to be 25% or less.

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