TWI574057B - Optical film, manufacturing method thereof, polarizing plate, and liquid crystal display device - Google Patents

Description

Optical film, manufacturing method thereof, polarizing plate, and liquid crystal display device

The present invention relates to an optical film, a method for producing the same, and a polarizing plate and a liquid crystal display device using the same. In particular, there is an optical film which can be preferably used as a polarizing plate protective film or an optical compensation film or the like.

The liquid crystal display device is an image display device that consumes less power and is space-saving, and its use is expanding year by year. The basic configuration of the liquid crystal display device is such that a polarizing plate is provided on both sides of the liquid crystal cell. The polarizing plate is responsible for light passing only the deflecting surface in the fixed direction, and the performance of the liquid crystal display device is greatly affected by the performance of the polarizing plate. The polarizing plate is usually configured such that a transparent protective film is bonded to both sides of the front and back of a polarizer including a polyvinyl alcohol film or the like which is adsorbed and coated with iodine or a dye. In recent years, the use of TVs for liquid crystal display devices has been progressing, and there has been an increasing demand for high image quality and low cost in response to an increase in size of screens. In particular, a liquid crystal display device of a vertical alignment (VA) mode is most commonly used as a liquid crystal display device for TVs because of its high contrast ratio and high manufacturing yield.

The cellulose-deposited cellulose film represented by the cellulose acetate film has high transparency, and can easily ensure the adhesion to the polyvinyl alcohol used for the polarizer. Therefore, it is used as a polarizing plate protective film or other retardation film exhibiting a phase difference. Various optical films have been widely used.

In recent years, with the expansion of the use of liquid crystal display devices, high-quality uses such as televisions have been expanding, and higher quality has been required for optical films to be used. For example, in order to improve the display quality, it is required to be uniform in the in-plane direction of the film. In order to be able to be installed outdoors, it is required to have less variation in optical characteristics accompanying changes in environmental humidity, or to require thinning or the like in accordance with the reduction in thickness of the liquid crystal display device itself.

As a method of producing the above optical film, a solution film forming method is widely known. In addition, it is generally known that when a solution film is formed into a film in a low speed region having a conveying speed of about 45 m/min, a film thickness which is parallel to a direction orthogonal to the film conveying direction is generated, so-called Segmental unevenness deteriorates. On the other hand, it is also generally known that the step-like unevenness can be improved to such an extent that the discharge rate of the polymer solution from the casting die is increased. However, in the high-speed region, although the step unevenness is good, peeling becomes difficult. Therefore, in order to impart solution casting suitability, it is necessary to perform peeling at a high speed by a cooling gelation method.

Further, Patent Document 1 discloses a method of improving the stepwise unevenness by performing stable high-speed casting: a solution film forming method in which a solution of a polymer material is cast on a moving support to form a film, and The casting portion of the solution is sucked to the suction operation on the upstream side in the traveling direction of the support, and the good solvent for the solute of the solution is dropped onto the ear portion of the casting portion to suppress the suction operation. The confusion of the above ear.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2003-181857 (Japanese Patent No. 3856114)

Here, the inventors of the present invention have implemented high by using a cooling gelation method. When the optical film of the film which improves the unevenness of the unevenness is manufactured by the method of peeling in a speed state, it is known that the fluctuation of the delay of the in-plane direction with the change of the environmental humidity of the obtained optical film is large. Further, when an optical film for improving a film having a stepped unevenness is produced by the method described in Patent Document 1, it is known that the surface shape is not improved to a level required for uniformity of the panel in recent years, and the film thickness is uniformized. The point of view is not sufficient.

An object of the present invention is to provide an optical film which is a film and which has improved uniformity of film thickness and which suppresses variations in retardation in the in-plane direction with changes in environmental humidity.

Based on the above-mentioned problems, the inventors of the present invention conducted active research and found that the viscosity of the polymer solution cast from the discharge device, the distance between the discharge device and the support, the casting speed, the casting speed, and the discharge device are controlled. The lip gap and the unextended dry film thickness are applied, and the pressure of the droplet portion of the polymer solution is sucked from the upstream side in the traveling direction of the support by the suction device, whereby the above problems can be solved, and the present invention has been completed.

Specifically, the above problem is solved by the following method.

[1] An optical film characterized by having a film thickness of 20 μm to 60 μm and satisfying the following formula (1) to formula (3): formula (1) PV (total) ≦ 0.5 μm

Formula (2) 2.5>PV(MD)/PV(TD)≧0.8

(In the equations (1) and (2), when the film thickness is measured by the interference film thickness meter in a circular region 10 having a diameter of 60 mm at a center of 60 mm in the film transport direction, PV (Comprehensive) indicates the difference between the maximum value and the minimum value of the film thickness at all points in each circular region, that is, the average value of 10 points of the total PV value, and PV (MD) indicates the diameter of the film transport direction in each circular region. The difference between the maximum value and the minimum value of the film thickness at all points above, that is, the average value of the length PV value at 10 points, and PV (TD) indicates all the diameters in the direction orthogonal to the film transport direction in each circular region. The difference between the maximum value and the minimum value of the film thickness of the point, that is, the average value of the width PV value at 10 points)

Formula (3) △Re(30-80)<3 nm

(In the formula (3), ΔRe (30-80) represents a value Re (30%) of the retardation in the in-plane direction at a relative humidity of 30% measured at a wavelength of 590 nm, and a film in-plane at a relative humidity of 80%. The absolute value of the difference in the direction of the direction Re (80%)).

[2] The optical film according to [1], wherein the following formula (4) is satisfied: Formula (4) 1.8>PV(MD)/PV(TD)≧0.8

(In the formula (4), when the film thickness is measured by the interference film thickness meter in a circular region 10 having a diameter of 60 mm at a center of 60 mm in the film transport direction, PV (MD) indicates each The difference between the maximum value and the minimum value of the film thickness at all points on the diameter of the film transport direction in the circular region The average value of 10 points of the length PV value, and PV (TD) indicates the difference between the maximum value and the minimum value of the film thickness at all points on the diameter in the film transport direction in each circular region, that is, 10 points of the width PV value. average value).

[3] The optical film according to [1] or [2] wherein the film thickness is from 25 μm to 45 μm.

[4] The optical film according to any one of [1] to [3] wherein the retardation Re in the in-plane direction measured at a wavelength of 590 nm is 0 nm ≦ | Re | ≦ 5 nm.

[5] The optical film according to any one of [1] to [4] which contains deuterated cellulose.

[6] A method for producing an optical film, comprising the steps of: casting a polymer solution from a discharge device to a traveling support; and reaching the support after the flow of the polymer solution. a step of sucking the droplet portion from the upstream side in the traveling direction of the support by a suction device; and transferring the polymer solution reaching the support at a casting speed of 15 m/min to 80 m/min to form a film shape And a step of controlling the film from the support by controlling the temperature of the peeling portion of the support to be 0° C. or higher; and satisfying the following formulas (11) to (14); Control: Formula (11) 1.0 × 10 ⁶ /min < (casting speed × unstretched dry film thickness) / (spraying portion gap) <1.0 × 10 ⁷ /min

Formula (11') unstretched dry film thickness = film thickness after stretching × {1 + (stretching ratio (%) in the film transport direction) / 100} × {1 + (stretching ratio in the direction orthogonal to the film transport direction ( %))/100}

(In the formula (11), the discharge portion gap indicates the lip gap (unit: m) of the discharge device, and the casting speed indicates the transfer speed of the support (unit: m/min))

Formula (12)-1000 Pa<Attraction pressure to droplets <-200 Pa

(In the formula (12), the suction pressure to the liquid droplets indicates the pressure applied to the liquid droplets by the suction device, and the negative pressure indicates the pressure in the direction in which the liquid droplets are attracted to the suction device side, and is represented by a positive value. The pressure in the direction of the suction device side

Equation (13) 0.25 mm≦h _k

(In the formula (13), h _k represents the distance (unit: mm) between the above-described discharge device and the above support)

Formula (14) 25 Pa. s<η

(In the formula (14), η represents the above-described discharge from the above-described discharge device The viscosity of the polymer solution, and indicates the vibrational viscosity (unit: Pa.s) of the polymer solution measured at 25 ° C, 1 Hz).

[7] The method for producing an optical film according to [6], wherein the casting speed is controlled to be 15 m/min to 55 m/min.

[8] The method for producing an optical film according to [6], wherein a total of the stretching ratio in the film conveying direction and the stretching ratio in a direction orthogonal to the film conveying direction is 5% to 20%.

[9] The method for producing an optical film according to any one of [6] to [8] wherein the extension is carried out in a manner satisfying the following formulas (15) and (16): (3%) ≦ (stretching ratio in the direction orthogonal to the film transport direction)

Formula (16) - 2% ≦ (stretching ratio in the film transport direction - stretch ratio in the direction orthogonal to the film transport direction).

[10] The method for producing an optical film according to any one of [6] to [9] wherein the viscosity of the polymer solution ejected from the ejection device is controlled so that the polymer solution is at 25 ° C The vibration viscosity η (unit: Pa.s) measured at 1 Hz satisfies the following formula (17): Formula (17) 30 Pa. s<η<200 Pa. s.

[11] The method for producing an optical film according to [6], wherein the distance h _k (unit: mm) of the discharge device from the support satisfies the following formula (18): Formula (18) 0.3 Mm≦h _k ≦ 1.5 mm.

[12] The method for producing an optical film according to any one of [6] to [11] wherein the polymer solution comprises deuterated cellulose.

[13] The method for producing an optical film according to any one of [6] to [12] wherein the polymer solution comprises at least one of a polycondensation ester compound and a sugar ester compound.

[14] The production method according to any one of [6] to [13] wherein the method further comprises: controlling the peeling portion of the support to a temperature of 10 ° C or higher, and peeling off the support The above film.

[15] An optical film produced by the method for producing an optical film according to any one of [6] to [14].

[16] A polarizing plate comprising: a polarizer; and the optical film according to any one of [1] to [5] and [15], wherein at least one side of the polarizer is contained.

[17] A liquid crystal display device comprising at least one polarizing plate according to [16].

According to the present invention, it is possible to provide an optical film which is a film and which improves the uniformity of the film thickness and which suppresses variation in retardation in the in-plane direction accompanying changes in environmental humidity.

Hereinafter, the contents of the present invention will be described in detail. The description of the constituent elements described below may be performed based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In addition, the "~" in the present specification is used in the meaning of including the numerical values described before and after the lower limit and the upper limit. In the present specification, the term "front side" means the display surface side, and the "back side" means the backlight side. In addition, the term "front side" as used in the present specification means "front contrast (hereinafter, the contrast is also referred to as CR)" with respect to the normal direction of the display surface, and refers to white brightness and black measured based on the normal direction of the display surface. The contrast calculated by the brightness.

[Optical film]

The optical film of the present invention (hereinafter also referred to as the film of the present invention) is characterized by having a film thickness of 20 μm to 60 μm and satisfying the following formulas (1) to (3).

Formula (1) PV (full) ≦ 0.5 μm

Formula (2) 2.5>PV(MD)/PV(TD)≧0.8

(In the equations (1) and (2), when the film thickness is measured by the interference film thickness meter in a circular region 10 having a diameter of 60 mm at a center of 60 mm in the film transport direction, PV (Comprehensive) indicates the difference between the maximum value and the minimum value of the film thickness at all points in each circular region, that is, the average value of 10 points of the total PV value, and PV (MD) indicates the diameter of the film transport direction in each circular region. Difference between the maximum and minimum values of the film thickness at all points above In other words, the average value of the length PV value is 10, and PV (TD) indicates the difference between the maximum value and the minimum value of the film thickness at all points on the diameter in the direction orthogonal to the film transport direction in each circular region, that is, the width PV. The average of 10 values. )

Formula (3) △Re(30-80)<3 nm

(In the formula (3), ΔRe (30-80) represents the value Re (30%) of the retardation in the in-plane direction at a relative humidity of 30% and the retardation value Re of the in-plane direction in the relative humidity of 80%. (80%) the absolute value of the difference.)

Hereinafter, the film of the present invention will be described.

<Characteristics of Optical Films> (film thickness)

The film of the present invention has a film thickness of 20 μm to 60 μm. Further, in the case where the film of the present invention is stretched, the film thickness after stretching is also 20 μm to 60 μm.

The film thickness of the film of the present invention is preferably 25 μm to 60 μm, more preferably 25 μm to 45 μm, particularly preferably 25 μm to 43 μm, and most preferably 25 μm to 41 μm.

(PV value)

The film of the present invention satisfies the above formula (1) and formula (2).

Formula (1) PV (full) ≦ 0.5 μm

Formula (2) 2.5>PV(MD)/PV(TD)≧0.8

(in the formulas (1) and (2), when in the film transport direction, respectively When the heart is separated by a distance of 60 mm and a circular area of 60 mm, the film thickness is measured by an interference film thickness meter. PV (full) indicates the maximum and minimum film thickness at all points in each circular area. The difference between the values is the average value of 10 points of the full PV value, and PV (MD) indicates the difference between the maximum value and the minimum value of the film thickness at all points on the diameter in the film transport direction in each circular region, that is, the length PV value. The average value of the ten points, PV (TD), indicates the difference between the maximum value and the minimum value of the film thickness at all points on the diameter in the direction orthogonal to the film transport direction in each circular region, that is, the width PV value at 10 points. average value. )

Here, the optical film satisfying the above formula (1) means that the difference between the maximum value and the minimum value of the film thickness in the film surface is small, that is, the film thickness is uniform in the film surface. The optical film satisfying the above formula (2) means that the difference between the maximum value and the minimum value of the film thickness in the film transport direction and the difference between the maximum value and the minimum value of the film thickness in the direction orthogonal to the film transport direction are the same, that is, It means that the film thickness unevenness in the conveyance direction of the film and the film thickness in the direction orthogonal to the conveyance direction are not the same.

On the other hand, when the film has a so-called step-like unevenness in which the direction orthogonal to the film transport direction is parallel, PV (MD) / PV (TD) becomes 2.5 or more, and conversely, if it is parallel to the film transport direction When the film thickness is uneven, PV (MD) / PV (TD) becomes less than 0.8.

Therefore, the optical film of the present invention which satisfies the above formulas (1) and (2) is a film in which the step unevenness is eliminated and the film thickness is uniform. When a film is formed by forming a film from a previous solution, it is difficult to produce such an optical film. However, according to the method for producing an optical film of the present invention to be described later, it can be produced at a low manufacturing cost.

The PV (overall) of the optical film of the present invention is preferably 0.45 μm or less, more preferably 0.40 μm or less.

The above PV (MD) / PV (TD) of the optical film of the present invention is preferably more than 0.8 and less than 2.5, and more preferably satisfies the following formula (4).

Formula (4) 1.8>PV(MD)/PV(TD)≧0.8

The PV (MD) is preferably 0.50 μm or less, more preferably 0.45 μm or less, and particularly preferably 0.40 μm or less.

The PV (TD) is preferably 0.50 μm or less, more preferably 0.45 μm or less, and particularly preferably 0.40 μm or less.

(delay)

The optical film of the present invention is characterized by satisfying the following formula (3).

Formula (3) △Re(30-80)<3 nm

(In the formula (3), ΔRe (30-80) represents a value Re (30%) of the retardation in the in-plane direction at a relative humidity of 30% measured at a wavelength of 590 nm, and a film in-plane at a relative humidity of 80%. The absolute value of the difference in the direction of the direction Re (80%).)

The optical film of the present invention is characterized in that the variation of Re caused by the environmental humidity is small. According to the conventional production method, it is difficult to produce the optical film of the present invention which satisfies the above-described formula (1) and formula (2) because the fluctuation of Re due to the environmental humidity is small and satisfies the above film thickness range, but will be described later. In the method for producing an optical film of the present invention, in the case of producing an optical film of the above film, a film having a uniform film thickness and a small humidity dependency of Re can be obtained.

The above ΔRe (30-80) is preferably less than 2 nm, more preferably less than 1 nm.

The film of the present invention preferably has a retardation Re of 0 nm ≦|Re|≦5 nm measured in the in-plane direction measured at a wavelength of 590 nm from the viewpoint of reducing light leakage when mounted on a liquid crystal display device. The above |Re| is preferably 0 nm ≦ | Re | ≦ 3 nm, more preferably 0 nm ≦ | Re | ≦ 2 nm.

The film of the present invention preferably has a retardation in the film thickness direction measured at a wavelength of 590 nm of -10 nm ≦ Rth ≦ 200 nm, more preferably 30 nm to 150 nm, and particularly preferably 35 nm to 130 nm.

Further, the film of the present invention is preferably a biaxial optical compensation film.

Here, the optical compensation film is biaxial, and represents nx, ny, and nz of the optical compensation film (nx represents a refractive index in the slow axis direction in the plane, and ny represents a refractive index in a direction orthogonal to nx in the plane, NZ represents a case where the refractive indices in the directions orthogonal to nx and ny are completely different, and in the case of the present invention, it is particularly preferable that nx>ny>nz.

The film of the present invention exhibits biaxial optical characteristics and is preferable in terms of reducing the color shift problem when the liquid crystal display device, particularly the VA mode liquid crystal display device, is viewed from an oblique direction.

In the present specification, Re(λ) and Rth(λ) respectively represent the in-plane retardation at the wavelength λ and the retardation in the thickness direction. In the present specification, the wavelength λ is set to 590 nm unless otherwise specified. Re(λ) is measured by injecting light having a wavelength of λ nm into the normal direction of the film in KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.). The film normal line with respect to the slow axis in the plane (determined according to KOBRA 21ADH) as the tilt axis (rotation axis) (any direction in the film surface is used as the rotation axis without the slow axis) The direction is inclined from the normal direction to 50 degrees on one side in units of 10 degrees, and light having a wavelength of λ nm is incident from the oblique direction, and the above-mentioned Re (λ) is measured at a total of 6 points, based on the measured delay value and average The assumed value of the refractive index and the input film thickness value, KOBRA 21ADH calculates Rth(λ). Further, the slow axis may be used as the tilt axis (rotation axis) (any direction in the film surface may be used as the rotation axis without the slow axis), and the retardation value may be measured from any two directions, based on the value and the average refractive index. The assumed value and the input film thickness value are calculated from the following formulas (A) and (B). Here, the assumed value of the average refractive index can be a value of a catalogue of a polymer handbook (JOHN WILEY & SONS, INC) and various optical films. The value of the average refractive index is unknown, and can be measured by an Abbe refractometer. The values of the average refractive index of the main optical film are exemplified below: deuterated cellulose (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), polystyrene (1.59). ). KOBRA 21ADH calculates nx, ny, and nz by inputting the assumed values of the average refractive indices and the film thickness. Based on the calculated nx, ny, and nz, Nz = (nx - nz) / (nx - ny) is further calculated.

Here, Re(θ) represents a retardation value in a direction inclined by an angle θ from a normal direction, and nx, ny, and nz represent respective principal axes of the refractive index ellipsoid. The refractive index of the bit, d represents the film thickness.

Rth=((nx+ny)/2-nz)×d (B)

In this case, as the parameter, the average refractive index n is required, and the average refractive index n is a value measured by using an Abbe refractometer (Abe refractometer 2-T manufactured by Atago Co., Ltd.).

(spot)

Further, it is preferred that the optical film of the present invention has a small amount of light when observed under crossed Nicols. The optical film of the present invention is characterized in that the film thickness of the segmental unevenness is uniformized, and in the preferred aspect of the optical film of the present invention, the spot when observed under crossed Nicols is also suppressed. The optical film in which such a light spot is also suppressed can be produced by a preferred aspect of the method for producing an optical film of the present invention to be described later.

(layer structure of the film)

The film of the present invention may be a single layer film or may have a laminated structure of two or more layers, but is preferably a single layer film.

(film width)

The film of the present invention preferably has a film width of 1000 mm or more, more preferably 1500 mm or more, and particularly preferably 1800 mm or more.

<polymer>

The film of the present invention is a polymer film.

The film of the present invention preferably contains a thermoplastic resin as a polymer as a main component. Here, the main component means 50% by mass of the total polymer. The above ratio of polymers.

The thermoplastic resin is not particularly limited as long as it does not contradict the gist of the present invention, but is preferably a thermoplastic resin suitable for solution film formation.

Examples of the thermoplastic resin include deuterated cellulose, a cyclic olefin resin, a styrene resin, and an acrylic resin.

Among them, the optical film of the present invention preferably contains deuterated cellulose.

Hereinafter, a preferred aspect of the optical film of the present invention, that is, a film containing deuterated cellulose is described. However, the present invention is not limited to a film containing deuterated cellulose. First, the deuterated cellulose used in the present invention will be described.

(deuterated cellulose)

The cellulose of the raw material of the deuterated cellulose used in the present invention may be cotton linter or wooded pulp (broadwood pulp, conifer pulp) or the like, and can be obtained by using any raw material cellulose. Cellulose can also be mixed as appropriate. For the detailed description of the raw material cellulose, for example, Maruzawa and Uda of the Nikkan Kogyo Shimbun (issued in 1970), "Plastic Materials Lecture (17) Cellulose Resin" or the Invention Association Public Technical Bulletin No. 2001- The cellulose described in the 1745 (page 7 to page 8) is not particularly limited to the cellulose-deposited layered film of the present invention.

First, the cellulose deuterated cellulose preferably used in the present invention will be described in detail. The glucose unit which constitutes β-1,4 linkage of cellulose has free hydroxyl groups at the 2, 3 and 6 positions. The deuterated cellulose is a polymer obtained by deuterating a part or all of some of the hydroxyl groups by using a mercapto group. The thiol substitution degree refers to the fiber located at 2, 3 and 6 positions. The ratio of the hydroxyl group of the vitamins to the deuteration (the 100% of each of the deuteration is the degree of substitution 1).

The mercapto group used in the deuterated cellulose of the present invention may be used alone or in combination of two or more kinds.

The mercapto group of the deuterated cellulose in the present invention may be an aliphatic group or an allyl group, and is not particularly limited. These are, for example, alkylcarbonyl esters, alkenylcarbonyl esters or aromatic carbonyl esters of cellulose, aromatic alkylcarbonyl esters and the like, and may each have a further substituted group. Preferred examples of the fluorenyl group include acetyl, propionyl, butanoyl, heptanoyl, hexanoyl, octanoyl, and anthracene. Decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, isobutanoyl ), tert-butanoyl, cyclohexanecarbonyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl, and the like. More preferably, these groups are an ethyl group, a propyl group, a butyl group, a fluorenyl group, a decyl group, a tributyl sulfonyl group, an oil fluorenyl group, a benzamidine group, a naphthylcarbonyl group, a cinnamyl group, and the like. Further, it is preferably an ethyl fluorenyl group, a propyl fluorenyl group or a butyl fluorenyl group (in the case where the fluorenyl group is a carbon number of 2 to 4), and the most preferred is an acetamino group (in the case where the cellulose fluorene is cellulose acetate).

That is, the above-mentioned deuterated cellulose may, for example, be triacetyl cellulose (TAC) or diacetyl cellulose (diacetyl cellulose, DAC), cellulose acetate propionate (CAP), cellulose acetate butyrate (CAB), cellulose acetate phthalate, and the like. From the viewpoint of delaying performance or cost, the deuterated cellulose film of the present invention preferably has a mercapto group of all of the above deuterated celluloses.

From the viewpoint of optical expression, the film of the present invention preferably has a thiol substitution degree of 2.0 to 2.9 in the above-mentioned deuterated cellulose. The thiol group substitution degree of the above deuterated cellulose is preferably from 2.1 to 2.89, particularly preferably from 2.4 to 2.86.

Further, when the film of the present invention has a fluorenyl group having 3 or more carbon atoms, the degree of substitution of the fluorenyl group having 3 or more carbon atoms is preferably from 0.3 to 1.0, more preferably from 0.4 to 0.9, particularly preferably from 0.5 to 0.8. .

Further, the degree of substitution of the thiol group can be determined in accordance with the method specified in ASTM-D817-96. The moiety that is not substituted with a thiol group is usually present as a hydroxyl group.

These deuterated celluloses can be synthesized by a known method, and can be synthesized, for example, by the method described in JP-A-10-45804.

In the deuteration of cellulose, when an acid anhydride or an acid chloride is used as the deuteration agent, an organic solvent such as acetic acid, dichloromethane or the like is used as the organic solvent of the reaction solvent.

As the catalyst, in the case where the oximation agent is an acid anhydride, it is preferred to use a protonic catalyst such as sulfuric acid, and in the case where the oximation agent is an acid chloride (for example, CH ₃ CH ₂ COCl), a base is used. Sex compounds.

The most common method for industrial synthesis of mixed fatty acid esters of cellulose is a method in which a mixed organic compound (acetic acid, propionic acid, valeric acid, etc.) or an acid anhydride of the fatty acid corresponding to an ethyl hydrazide group and other thiol groups is used. acid The ingredients degrade the cellulose.

The molecular weight of the above deuterated cellulose is preferably from 40,000 to 200,000, particularly preferably from 100,000 to 200,000, in terms of number average molecular weight (Mn). The deuterated cellulose used in the present invention preferably has a Mw/Mn ratio of 4.0 or less, and particularly preferably 1.4 to 2.3.

In the present invention, the average molecular weight and molecular weight distribution of deuterated cellulose or the like can be calculated by gel permeation chromatography (GPC) to calculate the number average molecular weight (Mn) and the weight average molecular weight (Mw), and the international publication WO2008- The method described in Japanese Patent Publication No. 126535 calculates the ratio.

<additive>

Various additives (for example, an ultraviolet preventive agent, a plasticizer, a deterioration preventive agent, fine particles, an optical property adjuster, etc.) can be added to the film of the present invention depending on the use.

(1) Sugar ester compounds and polycondensation esters

The film of the present invention preferably contains at least one of a sugar ester compound and a polycondensation ester from the viewpoint of lowering the internal haze of the film.

(1-1) Sugar ester compound - sugar residue -

The sugar ester compound refers to a compound in which at least one of a monosaccharide or a polysaccharide (for example, a hydroxyl group or a carboxyl group) constituting the compound is ester-bonded to at least one substituent. That is, the sugar ester compound referred to herein also includes a generalized sugar derivative, and for example, a compound containing a sugar residue such as gluconic acid as a structure is also included. That is, the above sugar ester compound It contains an ester of glucose and a carboxylic acid, and also contains an ester of gluconic acid and an alcohol.

The substitutable group in the monosaccharide or polysaccharide constituting the above sugar ester compound is preferably a hydroxyl group.

The sugar ester compound contains a structure derived from a monosaccharide or a polysaccharide constituting the sugar ester compound (hereinafter also referred to as a sugar residue). The structure of each monosaccharide of the above sugar residue is referred to as a structural unit of a sugar ester compound. The structural unit of the above sugar ester compound preferably contains a pyranose structural unit or a furanose structural unit, and more preferably all of the sugar residues are pyranose structural units or furanose structural units. Further, in the case where the above sugar ester contains a polysaccharide, it is preferred to contain both a pyranose structural unit or a furanose structural unit.

The sugar residue of the above sugar ester compound may be derived from 5 monosaccharides or 6 monosaccharides, but is preferably derived from 6 monosaccharides.

The number of structural units contained in the above sugar ester compound is preferably from 1 to 12, more preferably from 1 to 6, particularly preferably from 1 or 2.

In the present invention, the sugar ester compound is more preferably at least one esterified pyranose structural unit containing a hydroxyl group or one to 12 sugar ester compounds of a furanose structural unit, more preferably at least one containing a hydroxyl group. One or two sugar ester compounds of an esterified pyranose structural unit or a furanose structural unit.

Examples of the above-mentioned monosaccharide or a saccharide containing 2 to 12 monosaccharide units include erythrose, threose, ribose, arabinose, and xylose ( Xylose), lyxose, allose, altrose, grapes Glucose, fructose, mannose, gulose, idose, galactose, talose, trehalose, different Isotrehalose, neotrehalose, trehalosamine, kojibiose, nigerose, maltose, maltitol, isomaltose , sophorose, laminaribiose, cellobiose, gentiobiose, lactose, lactosamine, lactitol, lactulose Lactulose), melibiose, primeverose, rutinose, scillabiose, sucrose, sucralose, turanose, pod Vivianose, cellotriose, chacotriose, gentianose, isomaltotriose, isopanose, maltotriose Maltotriose), manninotriose, melezitose, panose, psyllium (planteose), raffinose, solatriose, umbelliferose, lycotetraose, maltotetraose, stachyose, baltopentaose, Belbalcose, maltohexaose, α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, δ-cyclodextrin -cyclodextrin), xylitol, sorbitol, and the like.

Preferred are ribose, arabinose, xylose, lyxose, glucose, fructose, mannose, galactose, trehalose, maltose, cellobiose, lactose, sucrose, sucralose, α-cyclodextrin, β-ring Dextrin, γ-cyclodextrin, δ-cyclodextrin, xylitol, sorbitol, especially arabinose, xylose, glucose, fructose, mannose, galactose, maltose, cellobiose, sucrose, --cyclodextrin, γ-cyclodextrin, particularly preferably xylose, glucose, fructose, mannose, galactose, maltose, cellobiose, sucrose, xylitol, sorbitol. Compared with the sugar ester compound having a maltose skeleton which is described as compound 5 in the example of the document [0059] of JP-A-2009-1696, it is compatible with the polymer. In other words, the above sugar ester compound preferably has a glucose skeleton or a sucrose skeleton.

- structure of the substituent -

The above-mentioned sugar ester compound used in the present invention preferably contains a substituent to be used and has a structure represented by the following formula (1).

General formula (1)(OH) _p -G-(LR ¹¹ ) _q (OR ¹² ) _r

In the formula (1), G represents a sugar residue, L ¹ represents any one of -O-, -CO, -NR ¹³ -, R ¹¹ represents a hydrogen atom or a monovalent substituent, and R ¹² represents an ester bond. A monovalent substituent for the bonding is carried out. p, q, and r each independently represent an integer of 0 or more, and p + q + r is equal to the number of hydroxyl groups in the case where the above-mentioned G is an unsubstituted saccharide having a cyclic acetal structure.

The preferred range of G above is the same as the preferred range of the above sugar residue.

The above L ^{1 is} preferably -O- or -CO-, more preferably -O-. When L ¹ is -O-, it is particularly preferred that the linking group derived from an ether bond or an ester bond is a linking group derived from an ester bond.

Further, when there are a plurality of L ¹ described above, they may be the same or different from each other.

It is preferred that at least one of R ¹¹ and R ¹² has an aromatic ring.

In particular, when L ¹ is -O- (that is, when R ¹¹ and R ¹² are substituted on the hydroxyl group in the above sugar ester compound), R ¹¹ , R ¹² and R ^{13 are} preferably selected from substituted. Or an unsubstituted fluorenyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted alkyl group, a substituted or unsubstituted amino group, more preferably substituted or unsubstituted An fluorenyl group, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, particularly preferably an unsubstituted fluorenyl group, a substituted or unsubstituted alkyl group, or an unsubstituted aryl group base.

Further, when a plurality of R ¹¹ , R ¹² and R ¹³ are respectively present, they may be the same or different from each other.

The above p represents an integer of 0 or more, and the preferred range is the same as the preferred range of the number of hydroxyl groups per monosaccharide unit to be described later. In the present invention, the above p is preferably zero.

The above r is preferably a number which is larger than the number of the pyranose structural unit or the furanose structural unit contained in the above G.

The above q is preferably 0.

Further, since p+q+r is equal to the number of hydroxyl groups in the case where the above-mentioned G is an unsubstituted saccharide having a cyclic acetal structure, the upper limit of the above p, q and r is based on the structure of G described above. Unanimous decision.

Preferable examples of the substituent of the above sugar ester compound include an alkyl group (preferably an alkyl group having 1 to 22 carbon atoms, more preferably an alkyl group having 1 to 12 carbon atoms, particularly preferably a carbon number of 1 to 8). An alkyl group such as a methyl group, an ethyl group, a propyl group, a hydroxyethyl group, a hydroxypropyl group, a 2-cyanoethyl group or a benzyl group, or an aryl group (preferably an aryl group having 6 to 24 carbon atoms), more preferably It is an aryl group having 6 to 18 carbon atoms, particularly preferably an aryl group having 6 to 12 carbon atoms, for example, a phenyl group, a naphthyl group, or a fluorenyl group (preferably a fluorenyl group having 1 to 22 carbon atoms, more preferably carbon). a fluorenyl group of 2 to 12, particularly preferably a fluorenyl group having 2 to 8 carbon atoms, for example: ethyl acetyl, propyl sulfonyl, butyl fluorenyl, pentylene, hexyl, octyl, benzhydryl, toluene Base, o-phthalic acid group, etc., guanamine group (preferably a decylamine having a carbon number of 1 to 22, more preferably a decylamine having a carbon number of 2 to 12, particularly preferably a decylamine having a carbon number of 2 to 8) For example, formamidine, etidamine, etc., quinone imine (preferably having a carbon number of 4 to 22, more preferably a carbon number of 4 to 12, and particularly preferably a carbon number of 4 to 8) For example, amber quinone imine, phthalimido, etc., aralkyl (preferably an aryl group having 7 to 25 carbon atoms, more preferably an aryl group having 7 to 19 carbon atoms). For carbon number 7~13 Group, for example: benzyl). More preferably, it is an alkyl group or a fluorenyl group, more preferably a methyl group, an ethyl fluorenyl group, a benzamidine group or a benzyl group, and particularly preferably an ethyl group and a benzyl group. Further, in the case where the constituent sugar of the above-mentioned sugar ester compound is a sucrose skeleton, it is described as compound 3 in [0058] of JP-A-2009-1696 and is used in the examples of the document. The sugar ester compound having a thiol group and a benzyl group as a substituent is preferable from the viewpoint of compatibility with a polymer as compared with the viewpoint of compatibility with a polymer.

In addition, the number of hydroxyl groups per structural unit (hereinafter also referred to as a hydroxyl group content) in the above-mentioned sugar ester compound is preferably 3 or less, more preferably 1 or less. Very good for zero. By controlling the hydroxyl group content within the above range, the movement of the sugar ester compound to the polarizing sheet layer and the polyvinyl alcohol (PVA)-iodine complex which occur over time under high temperature and high humidity conditions can be suppressed. The destruction is preferable in terms of suppressing degradation of the performance of the polarizer which occurs over time under high temperature and high humidity conditions.

The above sugar ester compound used in the film of the present invention preferably has no unsubstituted hydroxyl group, and the substituent contains only an ethyl fluorenyl group and/or a benzyl group.

Further, as a ratio of an ethylene group to a benzyl group in the above-mentioned sugar ester compound, a compound having a small ratio of a benzyl group to a certain extent is preferable because the black color change when incorporated in a liquid crystal display device is small. Specifically, the ratio of the benzyl group to the sum of all the unsubstituted hydroxyl groups and all the substituents in the above sugar ester compound is preferably 60% or less, preferably 40% or less.

As a method for obtaining the above-mentioned sugar ester compound, it can be obtained as a commercial product from those commercially produced by Tokyo Chemical Co., Ltd. and Aldrich, or by a known ester derivatization method for commercially available carbohydrates. (Similar to the method described in Japanese Laid-Open Patent Publication No. Hei 8-245678).

The number average molecular weight of the above sugar ester compound is preferably in the range of 200 to 3,500, more preferably in the range of 200 to 3,000, and particularly preferably in the range of 250 to 2,000.

Specific examples of the above-mentioned sugar ester compound which can be preferably used in the present invention are listed below, but the present invention is not limited to the following.

In the following structural formula, R each independently represents an arbitrary substituent, and a plurality of R's may be the same or different.

The sugar ester compound is preferably contained in an amount of 2% by mass to 30% by mass, more preferably 5% by mass to 20% by mass, based on the polymer (preferably cellulose fluoridation) contained in the film of the present invention. , especially good for containing 5% by mass ~15% by mass.

In addition, when the additive having a negative intrinsic birefringence is used in combination with the above-mentioned sugar ester compound, the amount (parts by mass) of the above-mentioned sugar ester compound is added to the additive amount (parts by mass) of the additive having a negative intrinsic birefringence. It is preferable to add 2 times to 10 times (mass ratio), and more preferably to add 3 times to 8 times (mass ratio).

In addition, when the polyester-based plasticizer described later is used in combination with the above-mentioned sugar ester compound, the amount (parts by mass) of the sugar ester compound is preferably added to the amount (parts by mass) of the polyester-based plasticizer. In order to add 2 times to 10 times (mass ratio), it is more preferable to add 3 times to 8 times (mass ratio).

Further, the above-mentioned sugar ester compounds may be used singly or in combination of two or more.

(1-2) Polycondensation ester compound

The polycondensation ester compound used in the present invention is preferably a polycondensation ester compound having a number average molecular weight of 300 or more and less than 2000 in order to prevent haze from occurring or to bleed or volatilize from the film. Chemical agent.

The polycondensation ester compound is not particularly limited, and a polyester-based plasticizer having an aromatic ring or a cycloalkyl ring in the molecule can be preferably used.

For example, an aromatic terminal polyester-based plasticizer represented by the following formula (2) is preferred.

General formula (2) B ¹ -(G ¹ -A ¹ )nG ¹ -B ¹

(wherein B ¹ represents a benzene monocarboxylic acid residue, and G ¹ represents an alkylene glycol residue having 2 to 12 carbon atoms or an aryl glycol residue having 6 to 12 carbon atoms or a carbon number of 4 to 12 An alkylene glycol residue, A ¹ represents an alkyl dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more. .)

In the formula (2), the polyester-based plasticizer is a benzene monocarboxylic acid residue represented by B ¹ , an alkylene glycol residue represented by G ¹ , an alkylene glycol residue or an aromatic group. a diol residue, and a compound of an alkyl dicarboxylic acid residue or an aryl dicarboxylic acid residue represented by A ¹ .

Examples of the benzene monocarboxylic acid component of the polyester-based plasticizer used in the present invention include benzoic acid, p-tert-butylbenzoic acid, o-toluic acid, m-toluic acid, p-toluic acid, and dimethylbenzoic acid. Ethyl benzoic acid, n-propyl benzoic acid, amino benzoic acid, ethoxy benzoic acid, and the like, and each of these compounds may be used alone or as a mixture of two or more kinds.

The polyester-based plasticizer preferably used in the present invention has 2 to 12 carbon alkyl diol components: ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,2-butyl Alcohol, 1,3-butanediol, 1,2-propanediol, 2-methyl1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl- 1,3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dihydroxymethylpentane), 2-n-butyl-2-ethyl-1 , 3 propanediol (3,3-dimethylol heptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3 - pentanediol, 2-ethyl1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-nonanediol, 1,12- As the octadecanediol or the like, these diols may be used alone or as a mixture of two or more kinds.

In particular, the alkylene glycol having 2 to 12 carbon atoms is preferred because it has excellent compatibility with deuterated cellulose.

Further, the polyester-based plasticizer used in the present invention has an alkylene glycol component having 4 to 12 carbon atoms, such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, or tripropylene glycol. Alternatively, these diols may be used alone or as a mixture of two or more kinds.

The polyester-based plasticizer having a carbon number of 4 to 12 used in the polyester-based plasticizer of the present invention is, for example, succinic acid, maleic acid, fumaric acid, or glutaric acid. And adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, etc., each of which may be used alone or as a mixture of two or more kinds. .

Examples of the aryldicarboxylic acid having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalene dicarboxylic acid, and 1,4-naphthalene dicarboxylic acid.

The number average molecular weight of the polyester-based plasticizer used in the present invention is preferably in the range of 300 to 1,500, more preferably in the range of 400 to 1,000.

Further, a compound having an acid value of 0.5 mgKOH/g or less and a hydroxyl value of 25 mgKOH/g or less is preferable, and a compound having an acid value of 0.3 mgKOH/g or less and a hydroxyl value of 15 mgKOH/g or less is more preferable.

Further, the polyester-based plasticizer used in the present invention may preferably be a polymer described in [0141] to [0156] of JP-A-2010-46834.

The polycondensation of the above polyester-based plasticizer is carried out by a usual method. For example, it can be easily synthesized by the following method: (i) by direct reaction of the above dibasic acid with a diol, the above dibasic acid or an alkyl ester of the dibasic acid a heat-melting condensation method such as a polyesterification reaction of a dibasic acid with a diol or a transesterification reaction; or (ii) a reaction of an acid chloride of the acid with a dehydrohalogenation of a diol The method, the polyester-based plasticizer used in the present invention is preferably obtained by a direct reaction.

The polyester-based plasticizer having a high distribution on the low molecular weight side has excellent compatibility with deuterated cellulose, and a deuterated cellulose film having a small moisture permeability after film formation and having transparency can be obtained.

The method of adjusting the molecular weight is not particularly limited, and a conventional method can be used. For example, although depending on the polymerization conditions, the method of blocking the ends of the molecules by using a monobasic acid or a monohydric alcohol can be controlled according to the amount of the monobasic compound to be added.

In this case, a monobasic acid is preferred in terms of stability of the polymer. For example, acetic acid, propionic acid, butyric acid, etc. may be mentioned, and it is selected not to be distilled to the outside of the system in the polycondensation reaction, but to be uniformly distilled to the outside of the reaction system when the monobasic acid is removed to the outside of the system after the reaction is stopped. The acid may also be used in combination with the monobasic acids.

Further, in the case of direct reaction, the number average molecular weight can also be adjusted by calculating the timing of stopping the reaction according to the amount of water removed by distillation in the reaction. In addition to this, it can be adjusted by changing the molar number of the added diol or dibasic acid, and can also be adjusted by controlling the reaction temperature.

The molecular weight of the polyester-based plasticizer used in the present invention can be measured by the above-described GPC measurement method or terminal group quantitative method (hydroxyl value).

The above polycondensation ester compound used in the present invention is preferably contained with respect to the above polymer (preferably deuterated cellulose) contained in the film of the present invention. It is 1% by mass to 40% by mass, more preferably 5% by mass to 30% by mass, and particularly preferably 7% by mass to 20% by mass.

The optical film of the present invention may contain a nitrogen-containing compound-based plasticizer or an additive which can be usually added to a cellulose-deposited cellulose film as an additive other than the above-mentioned sugar ester compound and polycondensate.

Examples of the additives include a nitrogen-containing compound-based plasticizer, a plasticizer other than the above-mentioned sugar ester compound, polycondensate ester, and nitrogen-containing compound plasticizer; fine particles; a retardation agent; and an additive having a negative intrinsic birefringence. Antioxidant, thermal deterioration preventive agent; colorant; ultraviolet absorber.

As the other additives described above, the compounds described in WO 2008-126535 can also be preferably used.

(2) Nitrogen-containing aromatic compound plasticizer

The optical film of the present invention preferably contains a nitrogen-containing aromatic compound-based plasticizer. The nitrogen-containing aromatic compound-based plasticizer is a nucleus of any one of pyridine, pyrimidine, triazine, and purine, and is replaceable in the mother nucleus. Any position has an alkyl group, an alkenyl group, an alkynyl group, an amine group, a decylamino group (refers to a structure in which an arbitrary fluorenyl group is bonded via a guanamine bond), an aryl group, an alkoxy group, a thioalkyloxy group, A compound having an alkyl group or an arylthio group (a group in which a sulfur atom is bonded to an alkyl group or an aryl group) or a heterocyclic group as a substituent. The substituent of the mother nucleus of the above-mentioned nitrogen-containing aromatic compound-based plasticizer may be further substituted with another substituent, and the other substituents are not particularly limited. For example, in the case where the above-mentioned parent core is substituted with an amine group, the amine group may be substituted by an alkyl group (the alkyl groups may be further bonded to each other to form a ring) or -SO ₂ R' (where R' represents an arbitrary substituent). The nitrogen-containing aromatic compound used in the present invention is preferably contained in an amount of 1% by mass to 40% by mass, more preferably 1% by mass to 15% by mass, even more preferably 2% by mass based on the fluorene cellulose. ~5 mass%.

Specific examples of the nitrogen-containing aromatic compound-based plasticizer are listed below, but the present invention is not limited by the following specific examples.

[Chemical 6]

[Chemistry 7]

(In the above formula R ¹ ~ R ³ represent the following compounds C-101 ~ C-180 in the R ¹ ~ R ³⁾

[11]

(In the above formula R ² ~ R ³ represent the following compounds C-181 ~ C-190 in R ² ~ R ³⁾

(Wherein R ³ represents the following compound D-101 ~ D-110 in R ³⁾

[化15]

[Chemistry 16]

[化17]

[化18]

[Chemistry 19]

[Chemistry 20]

[Chem. 21]

[化22]

[化23]

[Chem. 24]

(3) The above-mentioned sugar ester compound, polycondensate ester and nitrogen-containing compound are plasticized Plasticizer other than agent

In the film of the present invention, other plasticizers other than the above-described sugar ester compound, polycondensate ester, and nitrogen-containing compound-based plasticizer can be used.

As the other plasticizing agent, for example, a phosphate ester plasticizer, a trimellitate plasticizer, a pyromellitic acid plasticizer, a glycolate plasticizer, a citric acid ester can be preferably used. A plasticizer, a carboxylic acid ester plasticizer, an acrylic polymer, or the like.

Examples of the phosphate ester plasticizer include triphenyl phosphate (TPP), tricresyl phosphate (TCP), tolyldiphenyl phosphate, octyl diphenyl phosphate, and phosphoric acid. Diphenyl diphenyl phosphate (BDP), trioctyl phosphate, tributyl phosphate, etc.; as a carboxylic acid ester plasticizer, for example, dimethyl phthalate (DMP) , diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (diphenyl phthalate, DPP), diethyl hexyl phthalate (DEHP), triethyl O-acetylcitrate (OACTE), O-acetyl citrate Tributyl acrylate (OACTB), ethionyl triethyl citrate, butyl tributyl citrate, butyl oleate, methyl decyl ricinoleate, dibutyl sebacate , triacetin, tributyl tributyrin, butyl phthalate Butyl phthalyl butyl glycolate, ethyl phthalic acid ethyl glycolate, methyl phthalic acid ethyl Glycolate, butyl phthalic acid butyl glycolate, and the like.

Among these plasticizers, a phosphate ester plasticizer is preferably used, and more preferably TPP and BDP. In addition, these plasticizers may be used in combination of two or more kinds.

(4) Microparticles

As the fine particles which can be added to the optical film of the present invention, examples of the inorganic compound include cerium oxide, titanium oxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium citrate, and hydrated citric acid. Calcium, aluminum citrate, magnesium citrate and calcium phosphate.

In terms of the reduction in haze, the fine particles are preferably fine particles containing cerium, particularly preferably cerium oxide.

The average particle diameter of the primary particles of the microparticles is preferably from 5 nm to 50 nm, and more preferably from 7 nm to 20 nm. These fine particles are preferably contained mainly as secondary aggregates having a particle diameter of 0.05 μm to 0.3 μm.

The fine particles of cerium oxide are, for example, Aerosil R972, Aerosil R972V, Aerosil R974, Aerosil R812, Aerosil 200, Aerosil 200V, Aerosil 300, Aerosil R202, Aerosil OX50, Aerosil TT600, Aerosil NAX50 (above manufactured by Japan Aerosil Co., Ltd.) The product name is sold and can be used.

The fine particles of zirconia are sold, for example, under the trade names of Aerosil R976 and Aerosil R811 (all manufactured by Japan Aerosil Co., Ltd.), and can be used.

Examples of the polymer include an anthrone resin, a fluororesin, and an acrylic resin. It is preferably an anthrone resin, particularly preferably a polymer having a three-dimensional network structure, for example, Tospearl 103, Tospearl 105, Tospearl 108, Tospearl. 120. Tospearl 145, Tospearl 3120 and Tospearl 240 (made by Toshiba Silicone Co., Ltd.) are sold under the trade name of the product.

Among these fine particles, Aerosil 200V and Aerosil R972V are particularly preferably used because they not only keep the haze of the cellulose derivative film low, but also have a large effect of lowering the friction coefficient.

The content of the fine particles in the film of the present invention relative to the above polymer (preferably cellulose deuterated) is preferably 0.05% by mass to 1% by mass, particularly preferably 0.1% by mass to 0.5% by mass. In the case of a cellulose derivative film having a multilayer structure by a co-casting method, it is preferred to contain the added amount of fine particles on the surface.

(5) Delay performance agent

The film of the present invention may contain a delayed expression agent. High retardation performance is obtained at low stretch ratios by using a delayed expression agent. On the other hand, when the film of the present invention is produced by the production method of the present invention to be described later, the retardation performance is good even when the retardation agent is not contained.

The retardation agent is not particularly limited, and examples thereof include a compound containing a rod-shaped compound, a compound having a cyclic structure such as a cycloalkane or an aromatic ring, or a compound exhibiting delayed expression in the non-phosphate-based compound. . The compound having a cyclic structure is preferably a discotic compound. As the rod-like compound or the discotic compound, a compound having at least two aromatic rings can be preferably used as the retardation expression agent.

Further, two or more kinds of retardation agents may be used in combination.

The retardation agent is preferably in the wavelength region of 250 nm to 400 nm. There is maximum absorption, and preferably there is substantially no absorption in the visible region.

For example, the compound described in JP-A-2004-51648, JP-A-2007-86748, and the compound described in JP-A-2010-46834 can be used as the delayed expression material, but the present invention is not limited thereto. For these compounds.

For example, the compound described in the specification of the European Patent Application Publication No. 0911656A2, the triazine compound described in Japanese Patent Laid-Open Publication No. 2003-344655, and the Japanese Patent Publication No. 2008-150592 are also preferably used. The ternary benzene compound described in [0097] to [0108].

The discotic compound can be synthesized by a known method such as the method described in JP-A-2003-344655, and the method described in JP-A-2005-134884.

In addition to the above-mentioned disc-shaped compound, a rod-like compound having a linear molecular structure can be preferably used, and for example, a rod shape as described in JP-A-2008-150592 [0110] to [0127] can be preferably used. Compound.

(6) Intrinsic birefringence is negative additive

The film of the present invention may contain an additive having a negative intrinsic birefringence. Hereinafter, a compound having negative intrinsic birefringence which can be used as an additive having a negative intrinsic birefringence will be described.

The above-mentioned compound having negative intrinsic birefringence means a material which exhibits a negative intrinsic birefringence in a specific direction of the film in the deuterated cellulose film. The term "negative intrinsic birefringence" as used in this specification means birefringence Negative nature. Further, whether or not it has a negative intrinsic birefringence can be obtained, for example, by measuring the birefringence of a film in which a compound is added and a film in a system which is not added by using a birefringence meter, and comparing the differences.

The compound having a negative intrinsic birefringence of the present invention is not particularly limited, and a known compound or the like which exhibits a negative intrinsic birefringence can be used. For example, [0036] to [0036] of JP-A-2010-46834 can be preferably used. The compound disclosed in 0092].

Examples of the compound having negative intrinsic birefringence include a polymer having negative intrinsic birefringence or an acicular fine particle having negative intrinsic birefringence (acicular fine particles including a polymer having negative intrinsic birefringence). Hereinafter, a polymer having negative intrinsic birefringence which can be used in the present invention will be described.

The polymer having negative intrinsic birefringence refers to light having a refractive index of light in the alignment direction that is smaller than a direction orthogonal to the alignment direction when a layer is formed by uniaxial alignment of molecules. The refractive index of the polymer.

As such a polymer having a negative intrinsic birefringence, a negative polymer may be a polymer having a specific cyclic structure (a disc-shaped ring such as an aliphatic aromatic ring or a heteroaromatic ring) in a side chain (for example, poly (meth)acrylic polymerization such as styrene, poly(4-hydroxy)styrene, styrene-based polymer such as styrene-maleic anhydride copolymer or polyvinylpyridine, or polymethyl methacrylate a cellulose ester polymer (except for a polymer having a positive birefringence), a polyester polymer (excluding a polymer having a positive birefringence), an acrylonitrile polymer, an alkoxyalkylene polymer or Their multiple (binary, ternary, etc.) copolymerized polymers and the like. These polymers can be used alone. Two or more types may be used in combination. Further, in the case of a copolymer, it may be a block copolymer or a random copolymer.

Among them, a polymer having a specific cyclic structure, a (meth)acrylic polymer, and an alkoxyalkylalkyl polymer are more preferred, and polystyrene, polyhydroxystyrene, polyvinylpyridine, and (a) are preferred. Base) acrylic polymer.

When the above-mentioned polymer having a specific cyclic structure is added, the expression of Rth of the film after film formation can be improved, which is preferable.

The polymer having a specific cyclic structure can be preferably a polymer having an aliphatic aromatic ring in a side chain described in JP-A-2010-46834. Among them, polystyrene and poly(4-hydroxy)styrene are preferred, and a copolymer of polystyrene and poly(4-hydroxy)styrene is more preferred. The copolymerization ratio (mol ratio) of the copolymer of the above polystyrene and poly(4-hydroxy)styrene is preferably from 10/90 to 100/0, more preferably from 20/80 to 90/10.

On the other hand, as the polymer having a specific cyclic structure, a polymer having a heteroaromatic ring in a side chain such as polyvinyl pyridine can also be preferably used.

When the (meth)acrylic polymer is added, the film after film formation is excellent in transparency and extremely low in moisture permeability, and exhibits excellent performance as a protective film for a polarizing plate. For the above (meth)acrylic polymer, a compound described in JP-A-2009-1696 and WO 2008-126535 can be preferably used. Further, the above (meth)acrylic polymer may have an aliphatic aromatic ring or a heteroaromatic ring in the side chain.

In the case where the compound having negative intrinsic birefringence is a polymer having negative intrinsic birefringence, the weight average molecular weight thereof is preferably 500~. 100,000, more preferably 700~50,000, especially good 700~100000.

When the molecular weight is 500 or more, the volatility is good. When the molecular weight is 100,000 or less, the compatibility with the deuterated cellulose resin is good. Therefore, the film forming property of the cellulose fluorite film is also good, and both are preferable.

In the film of the present invention, it is preferred to add 0% by mass to 20% by mass of the above compound having a negative intrinsic birefringence with respect to the polymer (preferably deuterated cellulose) contained in the film of the present invention. More preferably, it is 0% by mass to 15% by mass, and particularly preferably 0% by mass to 10% by mass.

On the other hand, when the film of the present invention is produced by the production method of the present invention described later, the reverse wavelength dispersibility is large even when the relatively expensive compound having negative intrinsic birefringence is not contained. Therefore, from the viewpoint of reducing the production cost, the film of the present invention preferably has a small amount of a compound having a negative intrinsic birefringence.

(7) Antioxidant and thermal deterioration preventive agent

In the present invention, a commonly known compound can be used as the antioxidant and the thermal deterioration preventing agent. In particular, a lactone type, a sulfur type, a phenol type, a double bond type, a hindered amine type, or a phosphorus type compound can be preferably used. The compound described in International Publication WO2008-126535 can be preferably used for the above-mentioned antioxidant and thermal deterioration preventive agent.

(8) Colorant

Colorants can also be used in the present invention. The coloring agent is a dye or a pigment. In the present invention, it is a coloring agent which has an effect of making the color tone of a liquid crystal screen blue-tone or an effect of adjusting a yellow index and reducing the haze. Regarding the above coloring agent, international disclosure can be preferably used. The compound described in WO2008-126535.

[Method for Producing Optical Film of the Present Invention]

The method for producing an optical film of the present invention (hereinafter also referred to as the production method of the present invention) is characterized by comprising the steps of: casting a polymer solution from a discharge device to a traveling support; and performing the above polymerization on the casting The droplet portion of the solution reaching the support is sucked from the upstream side of the support in the traveling direction by the suction device; and the polymer solution reaching the support is cast at a rate of 15 m/min to 80 a step of forming the film into a film shape by m/min transfer; and controlling the film to be peeled off from the support so that the temperature of the peeling portion of the support reaches 0° C. or higher; and satisfying the following formula (11) )~ The method of equation (14) is controlled.

Formula (11) 1.0 × 10 ⁶ /min < (casting speed × unstretched dry film thickness) / (spraying portion gap) <1.0 × 10 ⁷ /min

Formula (11') unstretched dry film thickness = film thickness after stretching × {1 + (stretching ratio (%) in the film transport direction) / 100} × {1 + (stretching ratio in the direction orthogonal to the film transport direction ( %))/100}

(In the formula (11), the discharge portion gap indicates the lip gap (unit: m) of the discharge device, and the casting speed indicates the travel speed of the support (unit: m/min).)

Formula (12)-1000 Pa<Attraction pressure to droplets <-200 Pa

(In the formula (12), the suction pressure to the liquid droplets indicates the pressure applied to the liquid droplets by the suction device, and the negative pressure indicates the pressure in the direction in which the liquid droplets are attracted to the suction device side, and is represented by a positive value. The pressure in the direction of the suction device side.)

Equation (13) 0.25 mm≦h _k

(In the formula (13), h _k represents the distance (unit: mm) of the above-described discharge device from the support.)

Formula (14) 25 Pa. s<η

(In the formula (14), η represents the viscosity of the polymer solution ejected from the above-described discharge device, and indicates the vibration viscosity (unit: Pa.s) measured at 25 ° C and 1 Hz of the polymer solution.)

According to the manufacturing method of the present invention described above, by controlling the viscosity of the polymer solution cast from the discharge device, the distance between the discharge device and the support, the casting speed, and the casting speed, the lip gap of the discharge device and the unextended drying The film thickness is increased by applying a pressure of a droplet portion of the polymer solution from the upstream side in the traveling direction of the support by the suction device, and the optical film of the present invention is a film, and the uniformity of the film thickness is improved. The variation in the retardation in the in-plane direction accompanying the change in the environmental humidity is suppressed.

Hereinafter, the production method of the present invention will be described.

In the production method of the present invention, the optical film of the present invention can be produced by a solution casting film forming method. In terms of improving the planar shape of the film, the production method of the present invention preferably comprises the steps of forming a film comprising deuterated cellulose as the polymer by casting a solution by solution casting.

Hereinafter, the production method of the present invention will be described by taking a case where the solution casting film forming method is used as an example, but the production method of the present invention is not limited to the solution casting film forming method. Further, in the case where the above-described melt film forming method is used as the production method of the present invention, a known method can be used.

<Polymer solution>

In the solution casting film forming method, a ribbon solution is formed using a polymer solution (preferably a deuterated cellulose solution) containing deuterated cellulose or, if necessary, various additives which are preferably used as the above polymer. Hereinafter, a polymer solution which can be used in the solution casting film forming method (hereinafter also referred to as a deuterated cellulose solution or a dopant as appropriate) is used to produce deuterated cellulose based on a preferred aspect of the present invention. The method of the membrane is explained.

(solvent)

A polymer such as deuterated cellulose used in the present invention is dissolved in a solvent to form a dopant, and the doping stream is extended onto a substrate to form a film. At this time, it is necessary to evaporate the solvent after extrusion or casting, and therefore it is preferred to use a volatile solvent.

Further, the solvent is a solvent which does not react with a reactive metal compound or a catalyst or the like and does not dissolve the substrate for casting. Further, two or more solvents may be used in combination.

Further, the deuterated cellulose and the reactive metal compound capable of undergoing hydrolysis polycondensation may be separately dissolved in a different solvent and then mixed.

Here, an organic solvent having good solubility to the above-described deuterated cellulose is referred to as a good solvent, and in addition, an organic solvent which exhibits a main effect on dissolution and which is used in a large amount is referred to as a main (organic) solvent or main ( Organic solvents.

Examples of the above good solvent include ketones such as acetone, methyl ethyl ketone, cyclopentanone, and cyclohexanone, tetrahydrofuran (THF), 1,4-dioxane, and 1,3-dioxolane. Examples of the ethers such as 1,2-dimethoxyethane, esters such as methyl formate, ethyl formate, methyl acetate, ethyl acetate, amyl acetate, and γ-butyrolactone; Methyl cellosolve, dimethyl imidazolinone, dimethylformamide, dimethylacetamide, acetonitrile, dimethyl hydrazine, sulfolane, nitro Ethane, dichloromethane, methyl acetoxyacetate or the like is preferably 1,3-dioxolane, THF, methyl ethyl ketone, acetone, methyl acetate and dichloromethane.

In addition to the above organic solvent, the dopant preferably contains 1% by mass to 40% by mass of an alcohol having 1 to 4 carbon atoms.

After the doping stream is extended onto the metal support, the alcohol begins to evaporate and the ratio of the alcohol increases to cause the ribbon (the dopant after casting the dopant of the cellulose-deposited on the support) The film is referred to as a ribbon, gelled, and used as a gelling solvent to facilitate peeling from the metal support, or to promote deuteration of the non-chlorinated organic solvent when the proportion of the alcohol is small. The action of dissolving cellulose also inhibits reactive metallization The gelation, precipitation, and viscosity increase of the compound.

Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, isopropanol, n-butanol, second butanol, third butanol, and propylene glycol monomethyl ether.

Among these alcohols, ethanol is preferred in terms of excellent stability of the dopant, relatively low boiling point, good drying property, and no toxicity. These organic solvents have no solubility to deuterated cellulose when used alone, and are called poor solvents.

In the present invention, the deuterated cellulose constituting the deuterated cellulose film contains a hydrogen bonding functional group such as a hydroxyl group or an ester or a ketone. Therefore, from the viewpoint of reducing the peeling load on the casting support, it is preferably in the total The solvent contains 5% by mass to 30% by mass of the alcohol, more preferably 7% by mass to 25% by mass of the alcohol, and particularly preferably 10% by mass to 20% by mass of the alcohol.

By adjusting the alcohol content, the reproducibility of Re or Rth of the deuterated cellulose film produced by the production method of the present invention can be easily adjusted. Specifically, by increasing the alcohol content or setting the drying temperature (heat treatment temperature) before stretching in the production method of the present invention described later to be relatively low, the reach range of Re or Rth can be further increased.

Further, in the present invention, a small amount of water is also effective for increasing the viscosity of the solution or the film strength of the wet film state at the time of drying, or increasing the dopant strength of the drum method, for example, relative to the solution. The content is 0.1% by mass to 5% by mass, more preferably 0.1% by mass to 3% by mass, and particularly preferably 0.2% by mass to 2% by mass.

An example of a combination of organic solvents which are preferably used as a solvent of the polymer solution in the present invention is disclosed in Japanese Patent Laid-Open No. 2009-262551. In the newspaper.

Further, if necessary, a non-halogen-based organic solvent may be used as a main solvent, and it is described in detail in the Inventor's Association Technical Publication (publication number 2001-1745, issued on March 15, 2001, Invention Association).

The concentration of deuterated cellulose in the polymer solution in the present invention is preferably from 5% by mass to 40% by mass, particularly preferably from 10% by mass to 30% by mass, most preferably from 15% by mass to 30% by mass.

The concentration of the deuterated cellulose can be adjusted so that the stage in which the deuterated cellulose is dissolved in the solvent becomes a predetermined concentration. Further, a solution having a low concentration (for example, 4% by mass to 14% by mass) may be prepared in advance, and then concentrated by evaporating a solvent or the like. Further, a high concentration solution may be prepared in advance and then diluted. In addition, it is also possible to reduce the concentration of deuterated cellulose by adding an additive.

The period of adding the additive can be appropriately determined depending on the kind of the additive.

As a solvent which dissolves deuterated cellulose which is a preferable polymer compound satisfying the above conditions at a high concentration, an optimum solvent is a mixed solvent of a ratio of dichloromethane:ethanol of 95:5 to 80:20. Alternatively, it is also preferred to use a mixed solvent of methyl acetate:ethanol of 60:40 to 95:5.

<Details of each step> (1) Dissolution step

The dissolving step is a step of dissolving the deuterated cellulose and the additive while dissolving in a dissolving kettle in an organic solvent mainly composed of a good solvent for deuterated cellulose; or The additive solution is mixed in the cellulose solution to form a dopant.

For the dissolution of deuterated cellulose, a method carried out under normal pressure; a method carried out below the boiling point of the main solvent; a method of pressurizing at a boiling point of the main solvent or more; and, for example, Japanese Patent Laid-Open No. 9-95544 A method of performing a cooling and dissolving method as described in Japanese Laid-Open Patent Publication No. Hei 9-95538, or Japanese Patent Application Laid-Open No. Hei 9-95538, Various methods of dissolving such as the method to be carried out; and particularly preferably a method of pressurizing at a boiling point or higher of the main solvent.

The concentration of the deuterated cellulose in the dopant is preferably from 10% by mass to 35% by mass. An additive is added to the dopant during the dissolution or after dissolution to dissolve and disperse, and then filtered with a filter medium, defoamed, and then sent to the next step by a liquid feeding pump.

The method for producing an optical film according to the present invention is characterized in that the viscosity of the polymer solution ejected from the ejecting apparatus is controlled so that the visco-viscosity η of the polymer solution measured at 25 ° C and 1 Hz (unit: Pa.s) satisfies the following formula (14). By setting the vibration viscosity η as described above, it is possible to form a film by a solution film forming method so as to satisfy the conditions of the production method of the present invention.

Formula (14) 25 Pa. s<η

(In the formula (14), η represents the viscosity of the polymer solution ejected from the above-described discharge device, and indicates the vibration viscosity (unit: Pa.s) measured at 25 ° C and 1 Hz of the polymer solution.)

In the method for producing an optical film of the present invention, it is preferred to control the viscosity of the polymer solution ejected from the ejecting apparatus so that the visco-viscosity η of the polymer solution measured at 25 ° C and 1 Hz (unit: Pa.s) satisfies the following formula (17).

Formula (17) 30 Pa. s<η<200 Pa. s

The viscosity of the above polymer solution is preferably 40 Pa. s<η<200 Pa. s, especially good for 40 Pa. s<η<100 Pa. s.

(2) casting step, suction step, forming step

The casting step described above is a step of casting a polymer solution from the ejection device onto the traveling support. In a preferred embodiment, the following steps may be mentioned: conveying the dopant into the pressurizing mold by a liquid feeding pump (for example, a pressurized quantitative gear pump), an endless metal strip that is transferred in an infinite manner, such as a stainless steel belt, or a rotating metal drum. The dopant is cast from the slit of the pressurizing die at a casting position on the metal support.

The suction step is a step of sucking the droplet portion of the polymer solution that has reached the support until the support is moved from the upstream side in the traveling direction of the support by the suction device.

The molding step is a step of forming a polymer solution that has reached the support at a casting speed of 15 m/min to 80 m/min to form a film.

Further, in the casting step, the attracting step, and the forming step, the manufacturing method of the present invention is characterized in that the above formula (11) to formula (14) are satisfied. The way to control.

Hereinafter, preferred embodiments of the solution film forming method of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 5 is a schematic view showing a schematic configuration of a solution film forming apparatus to which the present invention is applied.

As shown in FIG. 5, the solution film forming apparatus 10 mainly includes a casting die (corresponding to the above-described discharge device), a casting tape (corresponding to the above-described traveling support) 14, and a decompression chamber 16 (corresponding to the above-described suction). Device).

The casting die 12 is disposed opposite the casting tape 14 at the position of the casting cylinder 20. A dopant containing a polymer material such as cellulose triacetate is extruded from the front end of the casting die 12 into a film shape. The extruded dopant temporarily adheres to the surface of the traveling casting belt 14 and is conveyed.

In the production method of the present invention, the distance h _k (unit: mm) between the discharge device and the support member satisfies the following formula (13).

Equation (13) 0.25 mm≦h _k

With this aspect, it is possible to reach the support until the liquid droplet portion reaches the support, and it is difficult to cause unevenness in film thickness caused by vibration of the discharge device or vibration due to suction of the suction device to be described later.

The distance h _k (unit: mm) between the discharge device and the support preferably satisfies the following formula (18).

Equation (18) 0.3 mm≦h _k ≦1.5 mm

The above h _{k is} preferably from 0.5 mm to 1.2 mm.

In the production method of the present invention, the discharge portion gap of the discharge device is controlled so as to satisfy the following formula (11).

Formula (11) 1.0 × 10 ⁶ /min < (casting speed × unstretched dry film thickness) / (spraying portion gap) <1.0 × 10 ⁷ /min

Formula (11') unstretched dry film thickness = film thickness after stretching × {1 + (stretching ratio (%) in the film transport direction) / 100} × {1 + (stretching ratio in the direction orthogonal to the film transport direction ( %))/100}

(In the formula (11), the discharge portion gap indicates the lip gap (unit: m) of the discharge device, and the casting speed indicates the travel speed of the support (unit: m/min).)

By controlling in the above manner, the portion of the liquid droplets ejected from the ejecting device can be prevented from becoming excessively long, and the droplet portion can reach the support, and the vibration of the ejecting device or the suction by the suction device described later is less likely to occur. The thickness of the film caused by the influence of vibration or the like is uneven.

The value of (the casting speed × unextended dry film thickness) / (the discharge portion gap) of the above formula (11) is preferably a lower limit value of 1.1 × 10 ⁶ /min or more, more preferably 1.2 × 10 ⁶ /min. the above. Further, the upper limit is preferably 9.0 × 10 ⁶ /min or less, more preferably 6.0 × 10 ⁶ /min or less.

The above-described discharge device is preferably a so-called mold, and is preferably a press mold which can adjust the slit shape of the die portion of the mold and which is easy to make the film thickness uniform. plus A press type mold or a T mold can be preferably used in the press mold. In order to increase the film forming speed, two or more press molds may be provided on the metal support, and the amount of the dopant may be divided to form a plurality of layers. Or a method of obtaining a film of a laminated structure by co-casting a plurality of dopants simultaneously.

On the other hand, the unextended dry film thickness of the film can be adjusted in such a manner as to satisfy the above formula (11), and the solid content concentration in the dopant and the narrowness of the die of the mold can be adjusted in such a manner as to have a desired thickness. Seam gap, extrusion pressure from the mold, metal support speed, etc.

The casting belt 14 is preferably formed in a ring shape and wound between the casting cylinder 20 and the driving cylinder (not shown). The casting cylinder 20 is preferably moved around the driving drum and the circumference of the casting cylinder 20 by rotating the driving cylinder.

The moving speed of the above-mentioned moving support is carried at a casting speed of 15 m/min to 80 m/min. Further, the above-described casting speed must be controlled so as to satisfy the above formula (11).

The casting speed is preferably from 15 m/min to 55 m/min, more preferably from 30 m/min to 55 m/min.

On the other hand, the decompression chamber 16 is provided on the upstream side of the casting die 12 with respect to the traveling direction of the casting belt 14, and is connected to the blower 24 via the suction pipe 22. By driving the blower 24, the inside of the decompression chamber 16 becomes a negative pressure, and the dopant in the gap between the casting die 12 and the casting tape 14 is temporarily attached to the side of the casting tape 14 in the casting portion 26. The surface gives an appeal. Thereby, even if the casting tape 14 is moved at a high speed, the stabilization of the dopant in the casting portion 26 is achieved.

In the production method of the present invention, the suction step is controlled so as to satisfy the following formula (12).

Formula (12)-1000 Pa<Attraction pressure to droplets <-200 Pa

(In the formula (12), the suction pressure to the liquid droplets indicates the pressure applied to the liquid droplets by the suction device, and the negative pressure indicates the pressure in the direction in which the liquid droplets are attracted to the suction device side, and is represented by a positive value. The pressure in the direction of the suction device side.)

Specifically, in the case where the suction portion is not attracted by the suction device, the droplet portion of the dopant may have a pattern as shown in FIG. 6, but in the manufacturing method of the present invention, by satisfying the above formula (12) The suction is performed in such a manner as to satisfy the above conditions, and the droplet portion can be partially deformed as shown in FIG. By partially deforming the droplets as described above, the distance from the discharge device to the droplet portion between the support members can be substantially shortened, and the distance h _k between the discharge device and the support can be approximated.

The above suction pressure to the liquid droplets is preferably -900 Pa < suction pressure to the liquid droplets < -300 Pa, more preferably -800 Pa < suction pressure to the liquid droplets < -350 Pa.

Further, it is preferable that a buffer tank 28 having a capacity of 10 to 100 times the pressure reducing chamber 16 is provided on the suction pipe 22 between the decompression chamber 16 and the blower 24 to prevent vibration from being transmitted to the decompression chamber 16.

As described above, according to the solution film forming apparatus 10 of the present embodiment, the optical of the present invention can be produced by any casting of 15 m/min to 80 m/min. membrane. That is, it is possible to manufacture not only an optical film having a film thickness of 20 μm to 60 μm, but also uniformity of film thickness, and variation in retardation in the in-plane direction accompanying changes in environmental humidity is suppressed, and 15 m can be suppressed. The film was produced by any casting of /min~80 m/min. Further, in the case of producing a film having a previous thickness of 80 μm, stable high-speed casting of 50 m/min or more can be performed.

(3) Solvent evaporation step

Preferably, the method comprises the steps of: heating a web (on the state before the finished product of the cellulose-deposited cellulose film and containing a large amount of solvent), heating the support, and evaporating the solvent until the ribbon It can be peeled off from the support.

In Fig. 1, the solvent evaporates and dries during the one-week travel of the casting belt 14, and the dopant on the casting belt 14 obtains the specified auto-supportability. Then, in the peeling step described later, the cast film is peeled off from the casting tape 14 at a position below the casting die 12, for example, to obtain a belt-shaped film.

In order to evaporate the solvent, there are the following methods: a method of blowing air from the side of the belt and/or a method of conducting heat by using a liquid from the back surface of the metal support, a method of conducting heat from the back surface of the front and the like by radiant heat, and the like; Good and better. Further, a method of combining the methods is also preferred. In the case where the liquid is thermally conductive on the back side, it is preferred to carry out heating at a temperature lower than the boiling point of the main solvent of the organic solvent used for the dopant or the organic solvent having the lowest boiling point.

(4) Stripping step

The stripping step is to strip the strip on which the solvent evaporates on the support. The step of stripping the position.

The method for producing an optical film according to the present invention includes the step of controlling the film from the support so that the temperature of the peeling portion of the support reaches 0° C. or higher.

The stripped strip is sent to the next step. Further, when the amount of the residual solvent of the ribbon at the time of peeling (the following formula) is too large, peeling is difficult, and if it is sufficiently dried and then peeled off on the metal support, a part of the ribbon peels off in the middle.

Here, as a method for increasing the film forming speed of the conventional production method (the peeling can be carried out when the residual solvent amount is as large as possible to increase the film forming speed), there is a gel casting method (gel casting). For example, a method of adding a poor solvent for deuterated cellulose to a dopant, a method of casting a dopant after casting, and a method of reducing the temperature of the metal support to perform gelation may be employed. It is known that the strength of the film at the time of peeling is improved by gelling the metal support in advance, and peeling can be accelerated to increase the film forming speed. On the other hand, the inventors of the present invention have found that the optical film obtained by gelation by the above-described conventional production method to increase the film forming speed (that is, the casting speed) lacks the uniformity of the film thickness. In other words, the method for producing an optical film of the present invention is characterized in that the temperature of the peeling portion of the support is controlled within the above range, and the film is not gelled and peeled off.

In the method for producing an optical film of the present invention, the temperature of the peeling portion of the support is preferably 10 ° C or higher, more preferably 10 ° C to 30 ° C.

The amount of residual solvent at the time of peeling of the ribbon on the support is preferably from 5 to 150% by mass based on the strength of the drying condition and the length of the support, but the amount of residual solvent is large. Stripping In the case of the economical speed and quality, the amount of residual solvent at the time of peeling is determined.

Moreover, it is preferable that the residual solvent amount of the ribbon at the peeling position is 10% by mass to 150% by mass, and particularly preferably 10% by mass to 120% by mass.

The amount of residual solvent can be expressed by the following formula.

Residual solvent amount (% by mass) = [(M-N) / N] × 100

Here, M is the mass at any time of the ribbon, and N is the mass when the ribbon of mass M is dried at 110 ° C for 3 hours.

(5) Drying and stretching steps

In the production method of the present invention, the elongation temperature is not particularly limited as long as it does not contradict the gist of the present invention. On the other hand, for example, from the viewpoint of improving the optical performance corresponding to the film thickness of the obtained cellulose-deposited cellulose film, it is preferred to carry out the above-described stretching step at a temperature of Tg - 5 ° C or lower (wherein Tg represents no The glass transition temperature (unit: ° C) of the deuterated cellulose film in the extended state. More preferably, the above stretching step is carried out at a temperature of not more than Tg - 5 ° C, particularly in a state where the deuterated cellulose film is never heated to a temperature of Tg - 5 ° C or higher.

After the peeling step, it is preferable to use a drying device that alternately transports the belts through a plurality of rollers arranged in the drying device, and/or a tenter that carries the both ends of the belt by the jig. The device is used to dry the ribbon.

In the manufacturing method of the present invention, the ribbon can be heated before being extended The treatment may or may not be carried out by heat treatment. However, in the case of heat treatment, when the glass transition temperature of the cellulose fluorite film is set to Tg, it is preferably not heated to Tg - 5 ° C or higher.

The method of drying and heat treatment is usually a method of blowing hot air on both sides of the ribbon, and heating the microwave instead of the wind. The temperature, the amount of air, and the time may vary depending on the solvent to be used, and may be appropriately selected depending on the type and combination of the solvent to be used.

In the production method of the present invention, it is possible to extend in any of the film transport direction (hereinafter also referred to as the longitudinal direction) and the direction orthogonal to the film transport direction (hereinafter also referred to as the lateral direction). More preferably, it is a method of biaxial stretching in the longitudinal direction and the transverse direction. The extension can be implemented in one phase or in multiple phases.

In the production method of the present invention, the total of the stretching ratio in the film conveying direction and the stretching ratio in the direction orthogonal to the film conveying direction is preferably 5% to 20%, more preferably 5% to 18%, and particularly preferably 5 %~16%.

In the production method of the present invention, it is preferable to satisfy the following formulas (15) and (16) from the viewpoint of reducing the absolute value of Re so as to satisfy 0 nm ≦ | Re | ≦ 5 nm. Extend.

Formula (15) 3% 延伸 (stretching ratio in the direction orthogonal to the film transport direction)

Formula (16) - 2% ≦ (stretching ratio in the film transport direction - stretching ratio in the direction orthogonal to the film transport direction)

The value of the above-mentioned (the stretching ratio in the film transport direction - the stretching ratio in the direction orthogonal to the film transport direction) is preferably 0% or more, and particularly preferably 3% to 6%.

The stretching ratio when extending in the film conveying direction is preferably 0% to 10%, more preferably 0% to 5%, and particularly preferably 0% to 2%. The stretching ratio (elongation) of the deuterated cellulose ribbon at the time of extension can be achieved by the difference in circumferential speed between the metal support speed and the stripping speed (stripping roller drawing). For example, when a device having two nip rolls is used, the rotation speed of the nip roller on the outlet side is faster than the rotation speed of the nip roller on the inlet side, so that it can be transported in the transport direction (longitudinal direction). Preferably, the cellulose film is extended. By performing the extension as described above, the expressiveness of the delay can be adjusted.

In addition, the "stretching magnification (%)" here is a value obtained by the following formula.

Extension ratio (%) = 100 × {(length after extension) - (length before extension)} / length before extension

The stretching ratio when extending in a direction orthogonal to the film conveying direction is preferably 3% or more, more preferably 3% to 10%, particularly preferably 3% to 8%.

Further, in the present invention, as a method of extending in a direction orthogonal to the film transport direction, it is preferable to extend using a tenter device.

(6) Reeling

In the coiler that winds up the obtained film, a coiler which is generally used can be used, and it can be wound up by a winding method such as a constant tension method, a constant torque method, a taper tension method, or a program tension control method in which internal stress is fixed. Light obtained in the above manner The film roll is preferably in the winding direction (the length direction of the film), and the slow axis direction of the film is ±2 degrees, and particularly preferably in the range of ±1 degree. Alternatively, it is preferably ±2 degrees, and particularly preferably ±1 degree, with respect to a direction at which the winding direction is a right angle (width direction of the film). Particularly preferably, the direction of the slow axis of the film is within ±0.1 degrees with respect to the winding direction (longitudinal direction of the film). Or preferably, the slow axis direction of the film is within ±0.1 degrees with respect to the width direction of the film.

The length of the film obtained in the above manner is preferably from 100 m to 10,000 m per roll, more preferably from 500 m to 7,000 m, and particularly preferably from 1,000 m to 6000 m. The width of the film is preferably from 0.5 m to 5.0 m, more preferably from 1.0 m to 3.0 m, and particularly preferably from 1.0 m to 2.5 m. Preferably, at the end of the winding, knurling is applied, and the width of the knurling is preferably 3 mm to 50 mm, more preferably 5 mm to 30 mm, and the height is preferably 0.5 μm to 500 μm. Good is 1 μm~200 μm. The knurling can be imparted to one side or to both sides.

The ribbon obtained in the above manner was taken up, and a cellulose-defluorated film as a final product was obtained.

[Polarizer]

The polarizing plate of the present invention comprises a polarizer and comprises at least one film of the present invention on at least one side of the polarizer. Hereinafter, the polarizing plate of the present invention will be described.

Like the film of the present invention, the aspect of the polarizing plate of the present invention includes not only a polarizing plate which is cut into a film of a size which can be directly incorporated into a liquid crystal display device, but also includes production by continuous production. a strip that grows into a strip and is wound into a roll (for example, a roll length of 2500 m or more or 3900 m) The polarizing plate on the surface). In order to be used for a large-screen liquid crystal display device, as described above, the width of the polarizing plate is preferably set to 1470 mm or more.

The specific configuration of the polarizing plate of the present invention is not particularly limited, and a known configuration can be employed. For example, the configuration described in Fig. 6 of JP-A-2008-262161 can be employed.

[Liquid Crystal Display Device]

The liquid crystal display device of the present invention comprises at least one sheet of the polarizing plate of the present invention.

The liquid crystal display device of the present invention is preferably a liquid crystal display device of an in-plane switching (IPS), an optically compensated bend (OCB) or a VA mode, and the liquid crystal display device is characterized by comprising a liquid crystal cell And a pair of polarizing plates disposed on both sides of the liquid crystal cell, and at least one of the polarizing plates is a polarizing plate of the present invention.

The specific configuration of the liquid crystal display device of the present invention is not particularly limited, and a known configuration can be employed. For example, an example of the configuration described in FIG. 1 can be employed. Further, the configuration described in Fig. 2 of Japanese Laid-Open Patent Publication No. 2008-262161 can also be preferably used.

[Example]

The invention will be further specifically described below by way of examples. The materials, the amounts used, the ratios, the processing contents, the processing order, and the like shown in the following examples can be appropriately changed without departing from the gist of the invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

Determination method

In the present invention, the measurement is carried out by the following measurement method.

(film thickness after extension, PV (comprehensive), PV (MD), PV (TD))

For the sample film, the film thickness, the full PV value, the length PV value, and the width PV value were measured by an interference film thickness meter in a circular region 10 having a diameter of 60 mm at a center of 60 mm in the film transport direction. The average value of the 10 points was obtained, and the results are shown in Tables 6 and 7 below as the film thickness after extension, PV (total), PV (MD), and PV (TD).

Further, the values of PV(MD)/PV(TD) were obtained, and the values thereof are also shown in Tables 6 and 7 below.

(Re, Rth)

The sample membrane was conditioned at 25 ° C and 60% relative humidity for 2 hours or more, and measured at a wavelength of 590 nm at 25 ° C and a relative humidity of 60% using a birefringence measuring device (KOBRA 21ADH, manufactured by Oji Scientific Instruments Co., Ltd.). The Re value and the Rth value are calculated.

The results of these are described in Tables 6 and 7 below. Further, in the table, when Re is negative, it means that there is a slow axis in the MD direction.

(△Re(30-80))

After adjusting the sample film for 12 hours at 25 ° C and a relative humidity of 30%, an in-plane retardation was measured at 25 ° C and a relative humidity of 60% using an automatic birefringence meter (KOBRA-21ADH: manufactured by Oji Scientific Instruments Co., Ltd.). Calculated by the value (Re). Further, it was calculated by measuring Re in the same manner as the above method except that the humidity was adjusted for 12 hours at 25 ° C and a relative humidity of 80%. The absolute value of the difference between these values is taken as the humidity dependency ΔRe of Re (30-80).

The results of these are described in Tables 6 and 7 below.

(film spot)

The sample film was visually observed under crossed Nicols, and the spot was evaluated based on the following criteria.

◎: The spot is not visible at all.

○: Very few spots were seen.

△: I saw a light spot.

×: The spot is strongly and clearly seen.

The results obtained are shown in Tables 6 and 7 below.

[Example 1 to Example 50 and Comparative Example 1 to Comparative Example 12] (1) Preparation of synthetic deuterated cellulose resin

The deuterated cellulose having a thiol substitution degree described in Tables 6 and 7 below was prepared. Sulfuric acid (7.8 parts by mass based on 100 parts by mass of cellulose) was added as a catalyst, and each carboxylic acid was added to carry out a deuteration reaction at 40 °C. Then, the total substitution degree and the 6-position substitution degree were adjusted by adjusting the amount of sulfuric acid catalyst, the amount of water, and the ripening time. The curing temperature was 40 °C. Further, the low molecular weight component of the deuterated cellulose was washed and removed with acetone.

(2) Preparation of dopants

The following composition was placed in a mixing tank, stirred to dissolve the components, and further heated to 90 ° C in about 10 minutes, and then filtered using a filter paper having an average pore diameter of 34 μm and a sintered metal filter having an average pore diameter of 10 μm. . The composition of the deuterated cellulose solution used in Example 1 is shown below.

The deuterated cellulose solution of the example 1 is 100.0 parts by mass of the deuterated cellulose described in the following Tables 6 and 7 and the additives described in the following Tables 6 and 7 (described in Tables 6 and 7 below). Quantity, unit: mass parts)

[Chem. 26]

T1: TPP/BDP (triphenyl phosphate/biphenyldiphenyl phosphate = 1/1 (mole ratio))

[化27]

<1-2> matting agent dispersion

Next, the following composition containing the deuterated cellulose solution produced by the above method was placed in a disperser to prepare a matting agent dispersion.

Matting agent dispersion:

100 parts by mass of the deuterated cellulose solution of the above Example 1, and matte The agent dispersion liquid was mixed, and the amount of the inorganic fine particles was 0.02 parts by mass relative to the deuterated cellulose resin, thereby preparing the film-forming dopant of Example 1. The results of measuring the vibrational viscosity (unit: Pa.s) at 25 ° C and 1 Hz of the obtained dopant are shown in Table 6 below.

In the other examples and comparative examples, the dopants for film formation were adjusted in the same manner except for the configurations described in the following Tables 6 and 7.

(3) Casting

The casting die is provided so that the distance h _k from the support becomes the height described in the following Table 6 and Table 7. Then, the above-mentioned dopant was extruded into a film shape from a casting die of a lip gap described in the following Tables 6 and 7, and cast at a casting speed described in Tables 6 and 7 below. At this time, the pressure of the decompression chamber was set to the pressures described in the following Tables 6 and 7, and the suction operation of the droplet portion was performed, and the casting was performed using a tape casting machine. In this case, the value of (the casting speed × unextended dry film thickness) / (the discharge portion gap) is a specific value, and the film thickness after the extension step described later is feedback-controlled, and the value is described below. Table 6 and Table 7. In addition, the belt is made of SUS.

(4) Stripping and drying

The ribbon (film) obtained by casting was peeled off from the tape at the peeling point of the support temperature described in the following Tables 6 and 7. Then, the tenter device that carried the both ends of the belt by the jig was used and dried in the tenter apparatus for 20 minutes.

(5) Extension

The obtained ribbon (film) is peeled off from the tape, and is sandwiched in a jig, and when the amount of residual solvent relative to the entire mass of the film is 30% to 5%, the fixed end is uniaxially stretched, and the following The stretching ratios described in Tables 6 and 7 extend in a direction (lateral direction) orthogonal to the film conveying direction by a tenter. In addition, the stretching ratio in the film conveyance direction applied to the film in the operation up to this point is described in Tables 6 and 7 below.

The fixture was then removed from the film and dried at 110 ° C for 30 minutes. At this time, the film thickness after the extension was the film thickness (unit: μm) after the extension described in Tables 6 and 7.

(6) Reeling

Then, after cooling to room temperature, each film was taken up, and in order to judge the manufacturing suitability, a minimum of 24 rolls having a roll width of 1280 mm and a roll length of 2600 mm were produced under the above conditions. For each of the 24 rolls which were continuously produced, a sample having a length of 1 m (width: 1280 mm) was cut at intervals of 100 m to obtain a film of each of the examples and the comparative examples, and each measurement was performed.

As can be seen from Tables 6 and 7, the film of the example is an optical film which is a film, and the uniformity of the film thickness is improved, and the variation in the retardation in the in-plane direction accompanying the change in the environmental humidity is suppressed.

On the other hand, Comparative Example 1 is a film obtained by thinning the film thickness so as to be lower than the lower limit of (the casting speed × unextended dry film thickness) / (the discharge portion gap), and the PV of the obtained film ( Overall) large, PV (MD) / PV (TD) value is also large, but also produces a spot.

In Comparative Example 2, the film was formed by lowering the casting speed so as to be lower than the lower limit of the (casting speed × unextended dry film thickness) / (spraying portion gap), and the obtained film had a large PV (total) and was also large. Produce a spot.

Comparative Example 3 is a film formed in an upper layer than the upper limit of the casting speed, and the obtained film has a large PV (total), a large PV (MD)/PV (TD) value, and a humidity dependency of Re. Also large.

Comparative Example 4 is a film produced without using a suction chamber, and the obtained film has a large PV (total) and a large PV (MD)/PV (TD) value, and a flare is also generated.

In Comparative Example 5, a film was produced in a state lower than the lower limit of the suction chamber pressure, and the obtained film had a large PV (total) and a large PV (MD)/PV (TD) value, and a flare was also generated.

Comparative Example 6 was a film made up to a state higher than the upper limit of the suction chamber pressure, and it was impossible to form a film.

Comparative Example 7 is a film prepared in a state lower than the lower limit of the support temperature at the time of peeling, and the moisture dependence of Re of the obtained film is extremely large.

Comparative Example 8 is in addition to lower than (casting speed × unstretched dry film thickness) In addition to the lower limit of the (spray portion gap), the film obtained in the aspect satisfying the conditions of the present invention has a large PV (total) and a flare.

Comparative Example 9 is a film which is formed by lowering the casting speed so as to be lower than the lower limit of (casting speed × unstretched dry film thickness) / (spraying portion gap), even if the film thickness is made in Comparative Example 2 The value of PV (MD) / PV (TD) of the obtained film was also large, and a spot was also generated.

Comparative Example 11 is a film which is formed in a state lower than the lower limit of the distance between the mold and the support, and cannot be formed into a film.

Comparative Example 12 was a film prepared in a state lower than the lower limit of the viscosity of the dopant solution, and it was impossible to form a film.

In addition, the film was attempted to be formed in a state in which the casting speed (the unrolled film thickness was not extended)/(the discharge portion gap) was 1.0 × 10 ⁷ /min or more, but the pressure in the discharge portion was suddenly increased, and an abnormality occurred, and the casting could not be completed. membrane.

The schematic views in a circular region when the film thicknesses of the optical films of Comparative Examples 5, 17, and 32 were measured by an interference film thickness meter are shown in FIGS. 2 to 4, respectively. As can be seen from the above figures, the film thicknesses of the optical films of Examples 17 and 32 were uniform in the plane as compared with the film thickness of Comparative Example 5.

[Example 101 to Example 150, Comparative Example 101 to Comparative Example 112] (Production of polarizing plate sample)

The surfaces of the films of the respective examples and comparative examples produced above were subjected to alkali saponification treatment. It was immersed in a 1.5 equivalent aqueous sodium hydroxide solution at 55 ° C for 2 minutes, followed by washing in a water bath at room temperature, and then neutralized at 30 ° C using 0.1 equivalent of sulfuric acid. It was again washed in a water bath at room temperature, and further dried at a temperature of 100 °C. Next, roll with a thickness of 80 μm The polyvinyl alcohol film was continuously extended to 5 times in an aqueous iodine solution, and dried to obtain a polarizer having a thickness of 20 μm. A 3% aqueous solution of polyvinyl alcohol (PVA-117H manufactured by Kuraray) was used as a binder, and films of the respective examples and comparative examples subjected to the above alkali saponification and Fujitac TD80UL (manufactured by Fuji Film Co., Ltd.) which were subjected to the same alkali saponification were prepared. In the case where the saponified surface was on the side of the polarizer, the polarizer was sandwiched between the polarizers, and the polarizing plates of the examples and the comparative examples, the polarizer, and the TD80UL were bonded in this order. At this time, the MD direction of each film and the slow axis of TD80UL are attached in parallel with the absorption axis of the polarizer.

(Production of liquid crystal display device)

A polarizing plate and a phase difference plate of a 42LE5500 peeling surface manufactured by LG Corporation, which is commercially available as an IPS panel, were used as a liquid crystal cell. As shown in Fig. 1 (the front side is the front side), the outer protective film 1 (Fujitac TD80UL manufactured by Fuji Film Co., Ltd.), the PVA polarizer 2, and the polystyrene produced below (polystyrene) are used as the adhesive 4, 4'. , PS) film 3, film 5 of each example, in this order, bonded to IPS liquid crystal cell 6 (the above IPS liquid crystal cell) and backside polarizing plate incorporated in the above-mentioned commercially available IPS panel (from liquid crystal cell 6 side) In this order, the adhesive 7 , the polarizing plate protective film 8 (Z-TAC manufactured by Fuji Film Co., Ltd.), the polarizing plate 2 ′, and the polarizing plate protective film 9 (Fujitac TD80UL manufactured by Fuji Film Co., Ltd.) were used to prepare the respective examples. Liquid crystal display device. At this time, the absorption axes of the polarizing plates described above are bonded to each other in an orthogonal manner. Hereinafter, a method of manufacturing a specific liquid crystal display device and an evaluation method will be described.

Commercially available polystyrene G9504, manufactured by PS JAPAN, was used.

A 25% by mass solution of polystyrene was prepared with respect to dichloromethane, and casting, drying, and peeling were carried out in the same manner as in the case of the cellulose-deposited cellulose film. The peeled film was subjected to 100% elongation at an extension temperature of 110 ° C in the TD direction.

The optical properties of the PS film were evaluated, and as a result, Re and Rth were -105 nm and -105 nm. Here, - means that the slow axis exists vertically with respect to the extending direction.

The PS film and the optical film produced in each example were bonded together via an adhesive, and the produced film was used as a laminate F. The PS film layer of the laminate F was subjected to corona treatment. Then, the laminate and the polarizer are bonded via a PVA paste so that the MD direction of the laminate F is parallel to the absorption axis of the polarizer, thereby producing a polarizing plate.

The 42LE5500 IPS panel manufactured by LG Corporation was disassembled, the polarizing plate on the front side was replaced, and the polarizing plate was attached to perform panel contrast, viewing angle characteristics, and surface evaluation.

As a result, the liquid crystal display device using the optical film of each example exhibited good performance.

1‧‧‧Outside protective film

2, 2'‧‧‧ PVA polarizer

3‧‧‧PS film

4, 4'‧‧‧Adhesive

5‧‧‧films of each case

6‧‧‧IPS liquid crystal cell

7‧‧‧Adhesive

8, 9‧‧‧ polarizing plate protective film

10‧‧‧solution film making device

12‧‧‧Spray device (casting die)

13‧‧‧ lip gap

14‧‧‧Support

15‧‧‧ film

16‧‧‧Attraction chamber

20‧‧‧Casting cylinder

22‧‧‧ suction tube

24‧‧‧Blowers

26‧‧‧ Droplet section (casting section)

28‧‧‧buffer tank

h _k ‧‧‧Distance of the ejection device from the support

1 is a schematic cross-sectional view showing an example of an IPS liquid crystal display device of the present invention.

FIG. 2 is a schematic view showing an example of the film thickness of the optical film of Comparative Example 5 measured by an interference film thickness meter.

3 is a schematic view showing an example of measurement of the film thickness of the optical film of Example 17 by an interference film thickness meter.

4 is a graph showing the film thickness of the optical film of Example 32 measured by an interference film thickness meter. A schematic diagram of an example.

Fig. 5 is a schematic view showing a schematic configuration of a solution film forming apparatus to which the present invention is applied.

6 is a schematic cross-sectional view showing an example of a state of a casting portion (droplet) at the time of film formation of a solution.

Fig. 7 is a schematic cross-sectional view showing another example of a state of a casting portion (droplet) at the time of film formation of a solution.

Claims (11)

A method for producing an optical film, comprising the steps of: casting a polymer solution from a discharge device to a traveling support; and discharging a droplet portion of the polymer solution to the support after casting a step of suctioning from the upstream side in the traveling direction of the support by the suction device; a step of forming the polymer solution reaching the support at a casting speed of 15 m/min to 80 m/min to form a film; and The method of controlling the film from the support by controlling the temperature of the peeling portion of the support to be 0° C. or higher, and controlling the method to satisfy the following formulas (11) to (14): ) 1.0 × 10 ⁶ /min < (casting speed × unstretched dry film thickness) / (spraying portion gap) <1.0 × 10 ⁷ /min (11') Unstretched dry film thickness = film thickness after stretching × {1 + (stretching ratio (%) in the film transport direction) / 100} × {1 + (stretching magnification (%) in the direction orthogonal to the film transport direction) / 100} (in the formula (11), the above-described discharge portion gap indicates The lip gap (unit: m) of the above-mentioned ejection device, and the casting speed indicates the traveling speed of the above support Degree (unit: m/min)); Formula (12) - 1000 Pa < suction pressure to droplets < -200 Pa (in the formula (12), the suction pressure to the droplets is expressed by the above-mentioned suction device to the above droplets The pressure indicates, by a negative value, the pressure in the direction in which the droplet is attracted to the suction device side, and the pressure in the direction from the suction device side in a positive value); Equation (13) 0.25 mm ≦h _k (Formula ( In the case of 13), h _k represents the distance (unit: mm) of the above-mentioned discharge device from the support; (14) 25Pa‧s < η (wherein n represents the above-described polymerization discharged from the above-described discharge device) The viscosity of the solution and the vibrational viscosity (unit: Pa ‧) measured by the polymer solution at 25 ° C and 1 Hz; the stretching ratio of the film transport direction and the direction orthogonal to the film transport direction The total extension ratio is 5% to 20%. The method for producing an optical film according to claim 1, wherein the casting speed is controlled to be 15 m/min to 55 m/min. The method for producing an optical film according to claim 1 or 2, wherein the method of satisfying the following formulas (15) and (16) is carried out. Extension: Formula (15) 3% ≦ (the stretching ratio in the direction orthogonal to the film transport direction); Formula (16) - 2% ≦ (the stretching ratio in the film transport direction - the direction orthogonal to the film transport direction) Extension ratio). The method for producing an optical film according to claim 1 or 2, wherein the viscosity of the polymer solution ejected from the ejecting device is controlled so that the polymer solution is measured at 25 ° C and 1 Hz. The above vibration viscosity η (unit: Pa ‧ s) satisfies the following formula (17): Formula (17) 30 Pa ‧ < η < 200 Pa ‧ s. The method for producing an optical film according to the first or second aspect of the invention, wherein the distance h _k (unit: mm) of the discharge device from the support body satisfies the following formula (18): Formula (18) 0.3 Mm≦h _k ≦ 1.5mm. The method for producing an optical film according to the above aspect, wherein the polymer solution comprises deuterated cellulose. The method for producing an optical film according to claim 1 or 2, wherein the polymer solution comprises a polycondensation ester compound and a sugar ester At least one of the compounds. The method for producing an optical film according to claim 1 or 2, further comprising the step of controlling the peeling portion of the support to a temperature of 10 ° C or higher, and peeling off the support from the support membrane. An optical film produced by the method for producing an optical film according to any one of claims 1 to 8. A polarizing plate comprising: a polarizer; and comprising an optical film according to claim 9 in at least one side of the polarizer. A liquid crystal display device comprising at least one polarizing plate according to claim 10 of the patent application.