JP2011034069A - Film and method for producing the same, polarizing plate and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hard-to-peel film, a method for producing the same, and a new vertical stretching method in which the equipment to be used is made compact and the equipment cost is lowered. <P>SOLUTION: The film includes a resin and 0.01-3 mass% solvent. A film fragment including an inclined azimuth and a thickness direction of the film in the plane thereof is disposed between two polarizing plates arranged in crossed nicols. The extinction positions, which are observed when the film fragment is turned within 0-90° angle while being irradiated with the light from the directions perpendicular to both surfaces of two polarizing plates, are different according to distances from one edge of the film fragment to the thickness direction thereof. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a film and a method for producing the film. The present invention also relates to a polarizing plate and a liquid crystal display device having the film.

Conventionally, an optical compensation film used in a liquid crystal display panel or the like has been oriented by stretching molecules to develop birefringence.
Such stretching is roughly classified into two, longitudinal stretching and lateral stretching, and longitudinal stretching and / or lateral stretching is appropriately selected according to desired optical properties. Among them, in the method for producing an optical compensation film by longitudinal stretching, two or more nip rolls are used, the film is passed between the nip rolls while heating the film, and the peripheral speed of the nip roll on the outlet side is set to the peripheral speed of the nip roll on the inlet side A method of stretching at a higher speed has been common (see, for example, Patent Document 1).

  Such a conventional longitudinally stretched film has a problem that in-plane peeling (a phenomenon in which the surface layer of the film is peeled off when an adhesive tape is applied to the film and then peeled off) easily occurs in the film. In recent years, the required optical compensation ability has been increasing, and it has become necessary to increase the draw ratio of the film as compared with the conventional film to develop birefringence. However, since the problem of in-plane peeling in the longitudinally stretched film as described above occurs remarkably with an increase in the draw ratio, improvement is desired at present.

  Further, when performing such longitudinal stretching, it is necessary to newly pass a large longitudinal stretching apparatus comprising a heating device and a plurality of pairs of nip rolls after the film is formed once. Therefore, the cost of the equipment itself and the large space for installation are the cause, and the film manufacturing cost is high. In recent years, there has been a demand for further film production cost reduction, and a new efficient method for producing an optical compensation film is required.

JP-A-10-239522

  The present invention has been made in consideration of the above-described problems, and an object of the present invention is to provide a film and a method for producing the same, and a film and a method for producing the same that are less likely to cause in-plane peeling in the film. Another object of the present invention is to provide a new method for producing a compact film with low equipment costs, particularly a method for producing a longitudinally stretched film. Furthermore, it is providing the polarizing plate, optical compensation film, antireflection film, and liquid crystal display device which use this film.

On the other hand, in the manufacturing method in which the inventors create a film by continuously clamping a resin dissolved in a solvent between a first clamping surface and a second clamping surface constituting the clamping device. As a result, it was found that it is possible to produce a film in which in-plane peeling hardly occurs in the film.
A feature of the present invention is that it is oriented by passing it through a pinching device while pinching the resin-containing composition of a semi-fluid (a state in which the fluidity before solidification is maintained). The system (a method of stretching a solid film between a plurality of pairs of nip rolls) is based on a completely different concept. In the manufacturing method of the present invention, the semi-fluid can be oriented only by passing between the clamping devices without giving a speed difference between the plurality of clamping members constituting the clamping device. The extinction position (structure in the cross-sectional direction) can be controlled by giving a peripheral speed difference between two pinching bodies that pinch a certain point. Such a structure cannot be formed by a conventional longitudinal stretching method. In addition, the aspect which gives a peripheral speed difference by the longitudinal stretch method using a nip roll is specifically, between the nip roll which pinched the upstream side at the time of a solid film being conveyed, and the nip roll which pinched the downstream side. This is a mode for providing a difference in peripheral speed, and a method of the present invention (for example, a mode in which a difference in peripheral speed is provided between upper and lower rolls constituting a pair of nip rolls sandwiching one part of a semi-fluid) And the specific embodiment is completely different.
That is, as a result of intensive studies to solve the above problems, the present inventors have found that the following production method and a film produced by the method can solve the above problems, and have completed the present invention described below. .

[1] A film containing a resin and containing 0.01 to 3% by mass of a solvent between two polarizing plates in which sections of the film containing an inclining direction and a thickness direction are arranged in crossed Nicols The extinction position observed when the film slice is rotated in the range of 0 ° to 90 ° while irradiating light from both sides perpendicularly to both surfaces of the two polarizing plates. Different films depending on the distance from one end of the slice in the thickness direction.
[2] The film according to [1], wherein extinction positions are observed at different angles within a range of 5 ° to 90 ° depending on a distance in a thickness direction from one end of the film piece.
[3] The film according to [1] or [2], wherein the first observed extinction position and the last observed extinction position differ by 5 ° or more when the film slice is rotated.
[4] A film containing a resin and containing 0.01 to 3% by mass of a solvent, and in a plane including a film normal and an orientation perpendicular to the film tilt orientation, a direction inclined by 40 ° from the normal A film having a circular letter length of more than 5 nm measured at 550 nm.
[5] The film according to any one of [1] to [4], which satisfies the following formulas (I) and (II):
30 nm ≦ Re [0 °] ≦ 600 nm (I) Formula (In Formula (I), Re [0 °] represents retardation in the in-plane direction at a wavelength of 550 nm measured from the film normal direction).
−600 nm ≦ Rth ≦ 600 nm (II) Formula (In Formula (II), Rth represents retardation in the thickness direction at a wavelength of 550 nm.)
[6] The film according to any one of [1] to [5], which satisfies the following formula (III):
30 nm ≦ γ ≦ 600 nm (III) Formula γ = | Re [+ 40 °] −Re [−40 °] | (III) In the formula (Formula (III) ′, Re [+ 40 °] is the film tilt direction and the film method. In the plane including the line, it represents retardation in the in-plane direction at a wavelength of 550 nm measured from a direction inclined to the tilt azimuth side by 40 ° with respect to the normal, and Re [−40 °] is relative to the normal Represents retardation in the in-plane direction at a wavelength of 550 nm measured from a direction tilted by −40 ° toward the tilt direction.)
[7] The film according to any one of [1] to [4], wherein the distribution of γ represented by the following formula (VI) is 1 to 30 nm.
γ distribution = maximum value of γ measured in the width direction−minimum value of γ measured in the width direction (VI)
γ = | Re [+ 40 °] −Re [−40 °] | (VI) ′
(In the formula (VI) ′, Re [+ 40 °] is an in-plane at a wavelength of 550 nm measured from a direction inclined to the tilt azimuth side by 40 ° with respect to the normal in a plane including the film tilt azimuth and film normal. (Re [−40 °] represents the retardation in the in-plane direction at a wavelength of 550 nm measured from the direction inclined by −40 ° to the tilt direction with respect to the normal line.)
[8] The film according to [7], which has a slow axis in the width direction.
[9] The film according to [7] or [8], which satisfies the following formulas (VII) and (VIII):
0 nm ≦ Re [0 °] ≦ 200 nm (VII) Formula −50 nm ≦ Rth ≦ 300 nm (VIII) Formula (In the formula (VII), Re [0 °] is the plane including the film tilt direction and the film normal. Represents in-plane retardation at a wavelength of 550 nm measured from the normal direction.)
[10] The film according to any one of [7] to [9], wherein the following formula (IX) is satisfied.
30 nm ≦ γ ≦ 200 nm (IX) formula γ = | Re [+ 40 °] −Re [−40 °] | (IX) ′ formula (in the formula (IX) ′, Re [+ 40 °] is the film tilt direction and the film method. In the plane including the line, it represents retardation in the in-plane direction at a wavelength of 550 nm measured from a direction inclined to the tilt azimuth side by 40 ° with respect to the normal, and Re [−40 °] is relative to the normal Represents retardation in the in-plane direction at a wavelength of 550 nm measured from a direction tilted by −40 ° toward the tilt direction.)
[11] The film according to any one of [1] to [10], wherein the concentration of the resin is uniform in the film thickness direction.
[12] The film according to any one of [1] to [11], including an additive, wherein the concentration of the additive is uniform in the film thickness direction.
[13] The film according to any one of [1] to [12], wherein the resin is a thermoplastic resin.
[14] A step of extruding a dope containing a resin and a solvent from the supply means as a semi-fluid film, a step of casting the extruded semi-fluid film on a support, and the cast semi-fluid film as a support The step of peeling from the step, the step of drying the peeled semi-fluid film, the step of controlling the residual solvent amount to 0.01 to 3% by mass, and the first and second pinching surfaces constituting the pinching device A method for producing a film, comprising the step of continuously pressing the semi-fluid film having a viscosity of 1 Pa · s to 100,000 Pa · s while applying a pressing pressure of 20 MPa to 500 MPa.
[15] The method for producing a film according to [14], wherein the semi-fluid film having a solvent amount of 30% by mass to 1000% by mass with respect to the solid content is sandwiched.
[16] The method for producing a film according to [14] or [15], wherein the support is a drum or a band.
[17] The method for producing a film according to any one of [14] to [16], wherein the semi-fluid film is sandwiched between the outlet of the supply unit and the support.
[18] The method for producing a film according to any one of [14] to [17], wherein the moving speed of the first pressing surface is made faster than the moving speed of the second pressing surface.
[19] The ratio of the moving speed difference between the first clamping surface and the second clamping surface of the clamping device defined by the following formula (V) to the speed of the first clamping surface is 0.5 to 20%. The method for producing a film according to any one of [14] to [18], which is characterized.
Formula (V)
Difference in moving speed (%) = 100 × {(moving speed of first pressing surface) − (moving speed of second pressing surface)}
/ (Moving speed of the first clamping surface)
[20] Any one of [14] to [19], wherein at least one of the first clamping surface and the second clamping surface is a surface of a metal touch roll having an outer cylinder thickness of 6 to 45 mm. A method for producing the film according to 1.
[21] Any one of [14] to [20], wherein the pressing device includes two rolls, and the first pressing surface and the second pressing surface are surfaces of the respective rolls. A method for producing the film according to 1.
[22] The method for producing a film according to any one of [14] to [21], wherein the support is controlled at −40 ° C. to 15 ° C.
[23] After the step of sandwiching the semifluid film, at least one of the step of volatilizing and solidifying the solvent in the semifluid film and the step of solidifying by immersing the semifluid film in a poor solvent The method for producing a film according to any one of [14] to [22], comprising a step.
[24] The method according to any one of [14] to [23], including a step of stretching the semifluid film at a stretch ratio of X times and a step of contracting Y times in a direction orthogonal to the stretch direction. The manufacturing method of the film of description.
1.00 <X <2.50
0.40 <Y <1.00
[25] The method for producing a film as described in [24], wherein the stretching is stretching in a direction perpendicular to the transport direction.
[26] The method for producing a film as described in [24] or [25], wherein the stretching step is performed before the clamping.
[27] The method for producing a film as described in any one of [14] to [26], wherein the resin is a thermoplastic resin.
[28] A film produced by the method for producing a film according to any one of [14] to [27].
[29] A polarizing plate using a polarizer and at least one film according to any one of [1] to [14] and [28].
[30] A liquid crystal display device using at least one film according to any one of [1] to [13] and [28].

  According to the manufacturing method of the present invention, it is possible to obtain a film that hardly causes peeling and a manufacturing method thereof. According to the production method of the present invention, a compact and low equipment cost can be obtained, and thus a film with a low production cost, particularly a longitudinally stretched film can be obtained. Moreover, according to the preferable aspect of the film of this invention, sufficient optical compensation is realizable when it uses for a liquid crystal display. Specifically, the film having the above optical characteristics can realize sufficient optical compensation when used in a TN mode, ECB mode, or OCB mode liquid crystal display. For example, since a viewing angle is narrow in a TN mode liquid crystal display, an optical compensation film (for example, a WV film (manufactured by Fujifilm)) provided with an optical compensation layer made of a liquid crystal composition that realizes optical compensation is usually used. An optical compensation layer made of a conventional liquid crystal composition is used without using an optical compensation layer made of a liquid crystal composition when the film according to a preferred embodiment of the present invention is used. Viewing angle compensation can be performed more simply than those using an optical compensation film having the above.

It is a top view showing the absorption axis of the polarizing plate, the orientation direction of a liquid crystal cell, and the slow axis of a film in the transflective ECB mode liquid crystal display device of the present invention. It is a schematic diagram showing the relationship between the rotation angle of the polarizing plate arranged in crossed Nicols and the extinction angle of the film, (A) is the extinction angle of the film of the present invention, (B) is the extinction angle of the conventional longitudinally stretched film. , (C) represents the extinction angle of a conventional inclined alignment film obtained by melt film formation, and (D) the rotation angle of a polarizing plate arranged in crossed Nicols.

  Hereinafter, the present invention will be described in more detail. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value. In the present specification, the “film longitudinal direction” means the MD (machine direction) direction. In the present specification, the “clamping body” represents only one of the first clamping surface and the second clamping surface, or both the first clamping surface and the second clamping surface.

[the film]
<First embodiment (film that is not stretched and contracted perpendicular to the stretching direction)>
Even if the film of the present invention is not contracted perpendicular to the stretching and stretching directions, it may be contracted perpendicular to the stretching and stretching directions. By such a difference in aspect, optical characteristics such as in-plane retardation Re and thickness-direction retardation Rth can be controlled. First, the optical characteristics of the film of the first embodiment that is not stretched and contracted perpendicular to the stretching direction will be described.

(Quenching position)
As a result of the analysis of the peeling phenomenon of the longitudinally stretched film by the present inventors, the molecules are oriented too straight with stretching, and the entanglement between the molecules is reduced. As a result, the in-plane interaction is reduced and peeling is likely to occur. I found out.
On the other hand, in the present invention, the two pieces of the film including resin, 0.01% to 3% of the solvent, and including the tilt direction and the thickness direction in the plane are fixedly arranged in crossed Nicols. An extinction position observed when the film piece is rotated in a range of 0 ° to 90 ° while irradiating light from a direction perpendicular to the plane of the polarizing plate is disposed between the polarizing plates. The said subject was solved by setting it as a film which changes with the distance to the thickness direction from. Here, in the present specification, the distance in the thickness direction from one end of the film slice refers to the distance from one end of the film slice using the x-axis, y-axis, and z-axis used in the description of Re and Rth described later. This represents the distance to the thickness direction (z-axis direction).

  The extinction position of the film cross section is when the cross section of the film section (film cut in parallel to the thickness direction) is observed under crossed Nicols, for example, while rotating the polarizing plate in the range of 0 ° to 90 ° with a polarizing microscope. Indicates the angle of the polarizing plate that darkens, and indicates that the polarizability of molecules is oriented in this direction or in a direction perpendicular thereto. When this extinction position varies depending on the distance in the thickness direction from one end of the film, it indicates that two or more layers having different orientation directions are present in the film. That is, all the molecules are not arranged in parallel in the thickness direction, indicating that delamination is unlikely to occur. In the present invention, such a structure is referred to as “a structure in which the extinction position varies depending on the distance in the thickness direction from one end of the film”. On the other hand, in the conventional longitudinal stretching method, molecules are only extended in the stretching direction between two pairs of nips, and therefore the extinction position has only one angle in the range of 0 ° or more and less than 90 °. That is, the extinction position is substantially the same regardless of the distance in the thickness direction from one end of the film. Such an extinction position may change continuously according to the distance from the surface in the thickness direction, or may be observed discontinuously at a plurality of angles. More preferable is when the images are observed discontinuously at a plurality of angles.

The range of the observed extinction position is preferably 1 to 45 degrees, more preferably 3 to 42 degrees, and still more preferably 5 to 40 degrees.
Furthermore, in the film of the present invention, when the film slice is rotated in the range of −90 ° to 90 °, the range of the extinction position observed is preferably 1 ° to 45 ° or −1 ° to −44 °, More preferably, it is 3 degrees to 42 degrees or -3 degrees to -42 degrees, and further preferably 5 degrees to 40 degrees or -5 degrees to -40 degrees. This angle is an angle at which the film is extinguished when the cross section of the film is observed with a polarizing microscope, based on a line parallel to the film surface.

  These extinction positions are more preferably different according to the distance in the thickness direction from one end of the film, and may be continuously changed and may be different. This is preferable because molecules having various orientations in the film cross section can be formed.

Specifically, the extinction position of the film of the present invention can be measured, for example, by the following method.
(1) The film is sampled to 5 mm (parallel to the tilt direction) × 10 mm (perpendicular to the tilt direction).
(2) About the said sample film, the surface of one edge part parallel to an inclination direction is smooth | blunted with a microtome (RM2265 by Leica).
(3) A surface 500 μm away from the smoothed surface is cut with a razor (Nisshin EM's single-blade trimming razor) parallel to the tilt direction, and the tilt direction and thickness direction of the film are included in the plane. Make a film section.
(4) Extinction change (darkest under crossed Nicols) for each of regions having different hues visually in the film thickness direction (difference in hue is derived from the difference in birefringence in the thickness direction) using the film slice State) is observed with a polarizing microscope (Eclipse E600POL manufactured by NIKON) in which two polarizing plates are arranged in crossed Nicols. Specifically, the film slices are arranged so as to be parallel to the two polarizing plates, the two polarizing plates are fixed in a state of being arranged in crossed Nicols, and the film slices are 0 ° to 90 °. Rotation is performed every arbitrary angle (for example, 1 °) within the range of, and the change in extinction is observed. At this time, the quenching occurs both when parallel to the absorption axis of the upper polarizer and when parallel to the absorption axis of the lower polarizer. To verify this for extinction position in either direction are present, it is inserted between a polarizer and parallel to intercept the retarder (e.g. lambda / 2 plate) the absorption axis of the two polarizers Also good. At this time, the extinction position exists in the direction in which the color of the sample segment changes (birefringence increases) in the direction in which the phase difference increases.
The light source used for observation with a polarizing microscope is not particularly limited, but a white light source is preferably used. The observation of the extinction position is not particularly limited as long as it is performed with crossed Nicols, or the extinction position is preferably determined based on an image observed with a crossed Nicol with a polarizing microscope. In addition, the film piece is disposed in parallel with the surfaces including the absorption axes of the two polarizing plates.

FIG. 2 is a schematic diagram of a polarizing microscope image observed when (A) the film of the present invention, (B) a conventional uniaxially stretched film, and (C) a conventional tilted alignment film are observed. In order to simply explain the features of the film of the present invention, a schematic diagram is prepared by dividing into four layers, but the film of the present invention is not limited to an embodiment divided into four layers. Moreover, the conventional stretched film is prepared by forming an unstretched film without forming a touch roll and then stretching it at Tg + 5 ° C. by 2.0 times using a tenter stretching machine.
In FIG. 2, the blacked-out portion represents the darkest color under crossed Nicols, and the luminance increases as the dot density decreases. The figure in the center (B) is a schematic diagram observing a section of a conventional stretched film. The extinction changes uniformly in the thickness direction, and there are extinction positions at 0 ° and 90 °. The right (C) is a schematic view of a section of a conventional tilted alignment film prepared based on the methods of JP-A-6-222213 and JP-A-2007-38646, and is uniformly quenched in the thickness direction. Changes, and an extinction position exists at about 15 °. On the other hand, the left (A) is the film of the present invention. Surprisingly, the quenching does not change uniformly in the thickness direction, and there are a plurality of quenching positions in the range of 0 ° to 90 °.

In the film of the present invention, it is preferable that the first observed extinction position differs from the last observed extinction position by 5 ° or more when the film slice is rotated in the range of 0 ° to 90 °, and preferably 10 ° or more. It is more preferable that they differ, and it is particularly preferable that they differ by 15 ° or more. The actually observed polarization microscope image does not have a clear multi-layer structure as shown in FIG. 2, but forms a continuous layer. Since the layer configuration cannot be measured beyond the resolution of the microscope, in the present invention, the change in the extinction position in the thickness direction observed in the above (1) to (4) is as shown in (i) and (ii) below. Decided. Moreover, it can be determined that the film of the present invention satisfies the following condition (iii).
(I) A polarizing microscope image observed in increments of 1 ° from 0 ° to 90 ° is divided by 1 μm in the thickness direction, and is divided into layers sequentially from the surface on one side.
(Ii) The change in luminance of the observed image of 0 ° to 90 ° is measured for each layer, and the angle at which the image becomes darkest, that is, the extinction position, is determined in the range of 0 ° to 90 °.
(Iii) It is determined whether or not the extinction positions of at least two layers differ by 5 ° or more.

  When the film of the present invention is used as, for example, an optical compensator of a liquid crystal display device, the magnitude of birefringence varies depending on the distance in the thickness direction measured from the film surface.

(Residual solvent amount)
Furthermore, in this invention, it is preferable to contain 0.01%-3% of a residual solvent in a film, More preferably, it is 0.03%-2%, More preferably, it is 0.05%-1%. Such a slight amount of solvent has an effect of suppressing delamination. That is, the presence of the residual solvent promotes the movement of polymer molecules in the film, and has an effect of easily forming entanglement between the molecules even after film formation. On the other hand, when the residual solvent does not exceed the above, it is possible to suppress the elimination of the structure in which the extinction position generated when the fluidity of the molecules is excessively increased depending on the distance in the thickness direction from one end of the film.
Although there is no restriction | limiting in particular about the measurement of the amount of residual solvents, For example, a film can be dissolved in the solvent for a measurement, and it can measure by GC. The solvent for dissolving the film for measurement is not particularly limited as long as it dissolves the resin (that is, a film or a semi-fluid film). For example, a cellulose acylate film, a polycarbonate film, or an acrylic film may be used. If there are, methyl acetate, dichloromethane, acetone, etc. can be used, and if it is a cycloolefin (COC, COP) film, n-hexane, cyclohexane, toluene, xylene, etc. can be used.

(solvent)
In this specification, a solvent refers to a molecule that is liquid at 25 ° C. and has a molecular weight of 20 to 200. The solvent amount of the present invention can be achieved by solution casting as described above.

  The solvent used in the present invention is not particularly limited as long as it can dissolve the resin, but preferably has a boiling point of 20 ° C to 200 ° C, more preferably 30 ° C to 150 ° C. Dichloromethane, acetone, ethyl acetate, methyl acetate, toluene, xylene, cyclohexanone, methanol, ethanol, propanol, butanol, dioxolane, water and the like can be preferably used. These solvents may be added so as to have the above viscosity with respect to the resin, but the resin concentration is preferably 5% to 40%, more preferably 10% to 35%.

(Circular litter dance)
The film of the present invention is a film containing a resin and containing 0.01 to 3% by mass of a solvent, and is 40 ° from the normal in a plane including a direction perpendicular to the film tilt direction and a film normal. Circular retardation (hereinafter also referred to as CRe [40 °]) at a wavelength of 550 nm measured from an inclined direction exceeds 5 nm. For example, the film of the present invention is subjected to tilt angle dependence of optical properties in a plane including a direction perpendicular to the tilt direction (y axis) and a film normal (z axis) using a Mueller matrix polarimeter of AXOMETRICS (USA). Is measured, the film has a circular retardance unlike a conventional film.
In general, TN, ECB, and OCB cells have a circular retardance because the tilt angle of liquid crystal molecules continuously changes in the thickness direction when a voltage is applied. Therefore, in order to compensate the viewing angle of the liquid crystal cell, it is preferable that this circular retardance can also be compensated. One feature of the film of the present invention is that, unlike the conventional film, the above-described circular retardance exceeds 5 nm, so that effective viewing angle compensation can be performed when used in the cell. Similar effects may be obtained in VA and IPS cells.

(In-plane retardation Re, thickness direction retardation Rth)
Further, the film of the present invention preferably satisfies the following formulas (I) and (II) in the case of a film that is not stretched and contracted perpendicular to the stretching direction.
30 nm ≦ Re [0 °] ≦ 600 nm (I) Formula (In Formula (I), Re [0 °] represents retardation in the in-plane direction at a wavelength of 550 nm measured from the film normal direction).
−600 nm ≦ Rth ≦ 600 nm (II) Formula (In Formula (II), Rth represents retardation in the thickness direction at a wavelength of 550 nm.)
More preferably 40 nm ≦ Re [0 °] ≦ 300 nm (I) ′ formula −300 nm ≦ Rth ≦ 300 nm (II) ′ formula More preferably 50 nm ≦ Re [0 °] ≦ 200 nm (I) ″ formula −200 nm ≦ Rth ≦ 200nm (II) '' formula

  By setting it in such a range, it can be effectively operated as an optical compensation film of a liquid crystal display panel and a λ / 4 wavelength plate of an organic EL display panel. A positive birefringent resin is preferably used in a region where Rth is positive, and examples thereof include a cycloolefin resin, a polycarbonate resin, a polyester resin, a polyolefin resin, and a polyvinyl alcohol resin. On the other hand, a negative birefringent resin may be used in a region where Rth is negative, and examples thereof include acrylic and polystyrene resins. Cellulose acylate resins can generally be classified as positive birefringent resins. However, if the degree of acyl substitution is increased and crystallization proceeds, negative birefringence can be obtained as described in JP-A-2007-249197. Can be expressed.

Furthermore, in the present invention, satisfying the following formula (III) is preferable in the case of a film that is not stretched and contracted perpendicular to the stretching direction.
30 nm ≦ γ ≦ 600 nm (III) Formula γ = | Re [+ 40 °] −Re [−40 °] | (III) ′ Formula (In Formula (III), Re [+ 40 °] is the film tilt direction and the film normal. Represents retardation in the in-plane direction at a wavelength of 550 nm measured from a direction inclined 40 ° toward the tilt direction with respect to the normal, and Re [−40 °] is inclined with respect to the normal Represents in-plane retardation at a wavelength of 550 nm measured from a direction inclined by -40 ° toward the azimuth.)
More preferably, 50 nm ≦ γ ≦ 300 nm (III-2) Formula, more preferably 70 nm ≦ γ ≦ 200 nm (III-3) Formula This large γ means that Re measured from an angle is different between the left side and the right side, for example. It means that an inclined structure was formed in the film when viewed from the thickness direction. This tilt structure has the effect of complementing the liquid crystal alignment in the liquid crystal display device and improving the viewing angle. Further, such an inclined structure has an effect of suppressing the in-plane orientation of molecules in the film layer and suppressing delamination. That is, delamination due to the molecules being arranged in the film surface direction can be suppressed by not falling below the above range, and delamination due to excessive orientation in the direction perpendicular to the film surface can be suppressed by not exceeding the above range.
Furthermore, when γ is within the above preferred range, the contrast when incorporated in a liquid crystal display device is remarkably improved, and the image unevenness is also suppressed.
In this specification, the “direction inclined by θ ° from the film normal” is defined as a direction inclined in the film surface direction by θ ° from the normal direction to the inclination direction. That is, the normal direction of the film surface is a direction with an inclination angle of 0 °, and an arbitrary direction within the film surface is a direction with an inclination angle of 90 ° when the sign of the inclination angle (θ) is not considered. . When considering the sign of the inclination angle (θ), the direction in which Re [+ 40 °] is measured and the direction in which Re [−40 °] are measured are positions symmetrical with respect to the film normal.
A film having γ, Re [0 °] and Rth in the above preferred ranges can be produced by the production method of the present invention described later. In addition, when the optical film having the preferable optical characteristics is used for optical compensation of a liquid crystal display such as a TN mode, an ECB mode, and an OCB mode, it contributes to the improvement of the viewing angle characteristics and achieves a wide viewing angle. it can.

  Variations in Re [0 °], Re [+ 40 °], and Re [−40 °] appear as display unevenness when used in a liquid crystal display. Therefore, the variation is preferably as small as possible. It is preferably within ± 3 nm, and more preferably within ± 1 nm. Similarly, the variation in the angle of the slow axis also causes display unevenness. Therefore, the variation is preferably as small as possible, specifically within ± 1 °, preferably within ± 0.5 °. It is more preferable that the angle is within ± 0.25 °.

In this specification, Re and Rth are the in-plane retardation (nm) and retardation in the thickness direction (nm) of a film-like object to be measured, such as an optically anisotropic layer, a film, or a laminate. To express.
Re [0 °] is measured by making light having a wavelength of 550 nm incident in the normal direction of a film-like measurement object in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments). In selecting the measurement wavelength λnm, the wavelength selection filter can be exchanged manually, or the measurement value can be converted by a program or the like.
When the film-like measurement object to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth is calculated by the following method.
Rth is defined by using Re as an in-plane slow axis (determined by KOBRA 21ADH or WR) as an inclination axis (rotation axis) (in the case where there is no slow axis, the in-plane of the film-like object to be measured) The light having a wavelength of 550 nm from the inclined direction in steps of 10 degrees from the normal direction to −50 ° to + 50 ° with respect to the normal direction of the film-like object to be measured. The KOBRA 21ADH or WR is calculated based on the retardation value, the assumed value of the average refractive index, and the input film thickness value.
In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative.
Retardation value from two inclined directions with the slow axis as the rotation axis (in the absence of the slow axis, the in-plane arbitrary direction of the film-like object to be measured is the rotation axis). Rth can also be calculated from the following formula (A) and formula (B) based on the measured value, the assumed value of the average refractive index, and the input film thickness value.
In the formula, Re [θ] represents a retardation value in a direction inclined by an angle θ from the normal direction.
In the formula (A), nx represents the refractive index in the slow axis direction (x-axis direction) in the plane, ny represents the refractive index in the y-axis direction orthogonal to nx in the plane, and nz represents nx And the refractive index in the z-axis direction orthogonal to ny, that is, the thickness direction, and d represents the film thickness.

In the case where a film-like measurement object to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a measurement object without a so-called optical axis, Rth is determined by the following method. Calculated.
Rth is an azimuth (respectively set to KOBRA 21ADH or WR) in which Re is set in the plane as a tilt axis (rotation axis) in a step of 10 degrees from −50 ° to + 50 ° with respect to the film normal direction. Measured 11 points with light having a wavelength of 550 nm incident from the inclined direction, and KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed average refractive index, and the input film thickness value. To do.
In the above measurement, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, INC) and catalogs of various optical compensation films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. Examples of the average refractive index values of main optical compensation films are as follows: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49) Polystyrene (1.59). The KOBRA 21ADH or WR calculates nx, ny, and nz by inputting the assumed average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.
Note that the measurement wavelengths of Re [θ °], Rth, and refractive index are values at a measurement wavelength of 550 nm unless otherwise specified.

In this specification, Re [0 °], Re [+ 40 °] and Re [−40 °] of the film were measured from the normal direction of the film using KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments). The retardation value at a wavelength of 550 nm (at an inclination angle of 0 °), the retardation value (at an inclination angle of 40 degrees) measured from a direction inclined by 40 ° toward the inclination azimuth side or the temporary inclination azimuth side with respect to the normal line, and Retardation value (at an inclination angle of −40 degrees) measured from a direction inclined by −40 ° toward the inclination azimuth side or provisional inclination azimuth side with respect to the normal line is represented.
Here, the inclination direction was determined by the following method.
(1) The slow axis direction in the film plane is 0 °, the fast axis direction in the film plane is 90 °, and the temporary tilt direction is set in increments of 0.1 ° between 0 ° and 90 °.
(2) Re [+ 40 °] and Re [−40 °] are measured from the direction inclined by 40 ° or −40 ° toward each temporary inclination direction with respect to the film normal, and | Re [+40 of each temporary inclination direction °] −Re [−40 °] |
(3) The direction in which | Re [+ 40 °] −Re [−40 °] | is maximized is determined as the tilt direction.
That is, in this specification, “having a tilted direction” means that there is an orientation in which | Re [+ 40 °] −Re [−40 °] |
In the present specification, Rth of the film is calculated by KOBRA 21ADH or WR using the tilt direction as the tilt axis (rotation axis).
In addition, variations in Re [0 °], Re [+ 40 °] and Re [−40 °] can be measured by the following method. Sampling is performed at 10 or more positions at 2 mm or more apart from each other in the center of the film, and Re [0 °], Re [+ 40 °] and Re [−40 °] are measured by the above method. The difference between the minimum values is the variation of Re [0 °], Re [+ 40 °], and Re [−40 °]. In the present invention, the average value of the above 10 points is Re [0 °], Re [+ 40 °], and Re [−40 °].
Further, the slow axis and the later-described Rth variation are also measured in the same manner.

(Film thickness)
The thickness of the film of the present invention is preferably 20 μm to 200 μm, more preferably 25 μm to 150 μm, still more preferably 30 μm to 90 μm.

(Surface roughness)
The film of the present invention preferably has a surface roughness Ra of 25 nm or less from the viewpoint of suppressing a decrease in contrast due to scattering when used as an optical compensator. The surface roughness Ra is more preferably 120 nm or less, and particularly preferably 80 nm or less.

  The film of the present invention preferably has a uniform resin concentration in the film thickness direction. That is, it is preferable that the resin composition has no gradient in the thickness direction. By eliminating the gradient in the composition in this way, it is possible to suppress the occurrence of intensity change (distribution) accompanying the composition change. As a result, it is possible to suppress in-plane peeling that occurs due to stress concentration in a weak place during the peeling test.

(resin)
The film of the present invention contains a resin. The type that can be used is not particularly limited as long as it can be dissolved in a solvent. The resin of the resin film that can be used in the present invention is a thermoplastic resin (by heating, because it is difficult to control because it is an application of the present invention during curing). It can be used even if it is easily deformed and deformed). However, a thermoplastic resin is preferable from the viewpoint of handling, and examples of the thermoplastic resin include cellulose ester resin, polycarbonate resin, polyethersulfone resin, acrylic resin, and polysulfone. Examples thereof include resins, polyarylate resins, polyethylene resins, polystyrene resins, polyvinyl chloride resins, and alicyclic olefin polymers. Among these, as the thermoplastic resin, a cellulose ester resin, a polycarbonate resin, a cyclic olefin resin, and an acrylic resin are preferable. Further, polyamide resins, polyimide resins, polyester resins, polyether ketone resins, polyamideimide resins, which are polymer materials having a photoelastic coefficient of 60 × 10 −8 cm 2 / N or more described in JP-A-2004-212971 Polyesterimide resin can also be preferably used. The following can be illustrated.

(A) Cellulose acylate resin The cellulose ester resin that can be used in the present invention is cellulose (di, tri) acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate. And at least one selected from cellulose phthalate.

  Among these, particularly preferable cellulose esters include cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, and cellulose acetate butyrate.

    As the substitution degree of the mixed fatty acid ester, more preferable cellulose acetate propionate and lower fatty acid ester of cellulose acetate butyrate have an acyl group having 2 to 4 carbon atoms as a substituent, and the substitution degree of an acetyl group is X. When the substitution degree of the propionyl group or butyryl group is Y, 2.0 ≦ X + Y ≦ 3.0 and 0.1 ≦ Y ≦ 2.9 are preferable, and the cellulose simultaneously satisfies the following formulas (XI) and (XII) A cellulose resin containing an ester is more preferable.

Formula (XI) 2.4 ≦ X + Y ≦ 3.0
Formula (XII) 1.0 ≦ X ≦ 2.5
Of these, cellulose acetate propionate is particularly preferably used. Among them, 1.9 ≦ X ≦ 2.5 and 0.1 ≦ Y ≦ 0.9 are preferable. The part not substituted with the acyl group is usually present as a hydroxyl group. These can be synthesized by known methods.

  Furthermore, the cellulose ester used in the present invention preferably has a weight average molecular weight Mw / number average molecular weight Mn ratio of 1.5 to 5.5, particularly preferably 2.0 to 5.0, Preferably it is 2.5-5.0, More preferably, the cellulose ester of 3.0-5.0 is used preferably.

  The cellulose ester raw material cellulose used in the present invention may be wood pulp or cotton linter, and the wood pulp may be softwood or hardwood, but softwood is more preferred. A cotton linter is preferably used from the viewpoint of peelability during film formation. The cellulose ester made from these can be mixed suitably or can be used independently.

  For example, the ratio of cellulose ester derived from cellulose linter: cellulose ester derived from wood pulp (coniferous): cellulose ester derived from wood pulp (hardwood) is 100: 0: 0, 90: 10: 0, 85: 15: 0, 50:50: 0, 20: 80: 0, 10: 90: 0, 0: 100: 0, 0: 0: 100, 80:10:10, 85: 0: 15, 40:30:30.

  The cellulose ester resin according to the present invention was charged with 1 g in 20 ml of pure water (electric conductivity 0.1 μS / cm or less, pH 6.8), and had a pH of 6 when stirred in a nitrogen atmosphere at 25 ° C. for 1 hr. It is preferable that the electric conductivity is 1 to 100 μS / cm. If the pH is less than 6, the residual organic acid may accelerate cellulose degradation during heating and melting, and if the pH is higher than 7, hydrolysis may accelerate. In addition, when the electrical conductivity is 100 μS / cm or more, since a relatively large amount of residual ions are present, it is considered to be a factor for degrading cellulose during heating and melting.

  The viscosity average degree of polymerization is preferably 190 to 550, more preferably 220 to 500, and still more preferably 250 to 450.

Further, it contains monovalent metal, divalent metal, sulfate radical, and nitrate radical, and the sum of monovalent metal and divalent metal is 1 ppm to 300 ppm, more preferably 10 ppm to 200 ppm, and still more preferably 20 ppm to 150 ppm. The sum of roots and nitrate radicals is 1 ppm to 300 ppm, more preferably 10 ppm to 200 ppm, and even more preferably 20 ppm to 150 ppm. The ratio of the equivalent of monovalent metal and divalent metal to the equivalent of sulfate radical and nitrate radical (1 (Valence metal + divalent metal / sulfate group + nitrate group) is 0.3 to 3, more preferably 0.5 to 2, and still more preferably 0.6 to 1.5.
Such cellulose acylates include, for example, JP-A-11-269304, JP-A-2002-265639, JP-A-2002-20410, JP-A-2003-41053, JP-A-2003-171500, JP-A-2003-71863, JP-A-2004-71336, JP-A-2004-231784, JP-A-2005-42039, JP-A-2005-104148, JP-A-2004-315574, JP-A-2005-154650, JP-A-2005-272485, Special JP 2005-309348, JP 2006-28387, JP 2006-83357, JP 2006-96878, JP 2006-233098, JP 2006-313190, JP 2007-238758, JP 2007-328370, JP2008-5 597, JP 2008-69233, JP 2008-83307, JP 2008-209595, JP 2006-36840, JP 2006-249221, JP 2007-216600, JP 2007-216600. , JP 2008-31396, JP 2008-63531, JP 2008-31396, JP 2008-137366, JP 2008-208231, JP 7-120017, etc. Can be used.

(B) Acrylic resin The acrylic resin of the present invention is a resin obtained by polymerizing acrylic acid, methacrylic acid and derivatives thereof as a main component and derivatives thereof, and is not particularly limited as long as the effects of the present invention are not impaired. A known methacrylic acid-based thermoplastic resin can be used. For example, the general formula (1)

(In the formula, R 1 and R 2 each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. Specifically, the organic residue is a linear or branched chain having 1 to 20 carbon atoms. Preferred examples of the compound (monomer) having a structure represented by a chain or cyclic alkyl group, acrylic acid, methacrylic acid and derivatives thereof include methyl (meth) acrylate, (meth ) Ethyl acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, 2-chloroethyl (meth) acrylate, (Meth) acrylic acid 2-hydroxyethyl, (meth) acrylic acid 3-hydroxypropyl, (meth) acrylic acid 2,3,4,5,6-pentahydroxyexyl and (meth) Acrylic acid 2,3,4,5-hydroxypentyl and the like. Among these, only 1 type may be used and 2 or more types may be used together. Among these, methyl (meth) acrylate (MMA) is most preferable in terms of excellent thermal stability.
Among acrylic resins, those containing 30 mol% or more of MMA units (monomer) are preferable in all monomers constituting the resin. In addition to MMA, at least one of a lactone ring unit, a maleic anhydride unit, and a glutaric anhydride unit is used. More preferably, for example, the following can be used. Among these, more preferred resins are (1) an acrylic resin containing a lactone ring unit, and (2) an acrylic resin containing a maleic anhydride unit.
The glass transition temperature (Tg) of these resins is preferably 106 ° C to 170 ° C, more preferably 110 ° C to 160 ° C, still more preferably 115 ° C to 150 ° C.

(1) Acrylic resin containing a lactone ring unit JP 2007-297615 A, JP 2007-63541 A, JP 2007-70607 A, JP 2007-100044 A, JP 2007-254726 A, JP 2007-254727 A , JP 2007-261265, JP 2007-293272, JP 2007-297619, JP 2007-316366, JP 2008-9378, JP 2008-76764, etc. Can be used. Among these, the resin described in JP-A-2008-9378 is more preferable.
(2) Acrylic resin containing maleic anhydride unit JP 2007-113109 A, JP 2003-292714 A, JP 6-279546 A, JP 2007-51233 A (described here), JP JP-A-2001-270905, JP-A-2002-167694, JP-A-2000-302988, JP-A-2007-111110, JP-A-2007-11565 can be used. Among these, the one described in JP 2007-113109 A is more preferable. A commercially available maleic acid-modified MAS resin (for example, Delpet 980N manufactured by Asahi Kasei Chemicals Corporation) can also be preferably used.
(3) Acrylic resin containing glutaric anhydride unit JP-A-2006-241263, JP-A-2004-70290, JP-A-2004-70296, JP-A-2004-126546, JP-A-2004-163924, JP-A-2004 -291302, JP-A-2004-292812, JP-A-2005-314534, JP-A-2005-326613, JP-A-2005-331728, JP-A-2006-131898, JP-A-2006-134882, JP-A-2006- 206881, JP 2006-241197, JP 2006-283013, JP 2007-118266, JP 2007-176982, JP 2007-178504, JP 2007-197703, JP 2008-74818. No., International Publication WO2005 / 105 The thing of each 918 gazette can be used. Among these, those described in JP-A-2008-74918 are more preferable.
(4) Other acrylic resin An acrylic resin containing a glutarimide group described in JP-A-2006-337493 can also be preferably used.

(C) Polycarbonate resin In the present invention, various known polycarbonate resins can also be used. In the present invention, it is particularly preferable to use an aromatic polycarbonate. There is no restriction | limiting in particular about the said aromatic polycarbonate, and there will be no restriction | limiting in particular if it is an aromatic polycarbonate from which the various characteristics of a desired film are acquired.

  In general, a polymer material generally called polycarbonate is a generic name of a polymer material in which a polycondensation reaction is used in the synthesis method and the main chain is linked by a carbonic acid bond. , Phosgene, diphenyl carbonate and the like obtained by polycondensation. Usually, an aromatic polycarbonate represented by a repeating unit having 2,2-bis (4-hydroxyphenyl) propane called bisphenol-A as a bisphenol component is preferably selected, and various bisphenol derivatives should be selected as appropriate. Thus, an aromatic polycarbonate copolymer can be formed.

  In addition to this bisphenol-A, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 9,9-bis (4-hydroxyphenyl) fluorene, 1,1 -Bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 2,2-bis (4-hydroxyphenyl) -2-phenyl Ethane, 2,2-bis (4-hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane, bis (4-hydroxyphenyl) diphenylmethane, bis (4-hydroxyphenyl) sulfide, bis ( 4-hydroxyphenyl) sulfone, 1,1-bis (4-hydroxyphenyl) -3,3,5-tri Mention may be made of a chill cyclohexane, and the like.

  It is also possible to use an aromatic polyester carbonate partially containing terephthalic acid and / or isophthalic acid components. By using such a structural unit as a part of the structural component of the aromatic polycarbonate composed of bisphenol-A, the properties of the aromatic polycarbonate, such as heat resistance and solubility, can be improved. The present invention is also effective for coalescence.

  If the aromatic polycarbonate used here has a viscosity average molecular weight of 10,000 or more and 200,000 or less, it is suitably used. A viscosity average molecular weight of 20,000 to 120,000 is particularly preferred. If a resin having a viscosity average molecular weight lower than 10,000 is used, the mechanical strength of the obtained film may be insufficient, and if it has a high molecular weight of 400000 or more, the viscosity of the dope becomes too high, which causes problems in handling. The viscosity average molecular weight can be measured by commercially available high performance liquid chromatography.

  The glass transition temperature of the aromatic polycarbonate according to the present invention is preferably 200 ° C. or higher in order to obtain a highly heat-resistant film, and more preferably 230 ° C. or higher. These can be obtained by appropriately selecting the copolymerization component. The glass transition temperature can be measured with a DSC apparatus (differential scanning calorimetric analyzer). For example, the baseline is unevenly determined by a temperature rising condition of 10 ° C./min with RDC220 manufactured by Seiko Instruments Inc. It is the temperature that begins to do.

  In the present invention, the solvent used in the dope composition containing the aromatic polycarbonate is a mixed solvent containing 4 to 14 parts by mass of methylene chloride and a linear or branched aliphatic alcohol having 1 to 6 carbon atoms. It is preferable.

  The amount of the linear or branched aliphatic alcohol having 1 to 6 carbon atoms is preferably 4 to 12 parts by mass. Using such a mixed solvent, by peeling the web with a higher residual solvent concentration than conventional, it is possible to suppress the generation of strong static electricity at the time of web peeling, thereby damaging the belt, film streaks and unevenness, It is possible to prevent the occurrence of minute scratches.

  The type of alcohol added is limited by the solvent used. It is a necessary condition that the alcohol and the solvent are compatible. These may be added alone or in combination of two or more. The alcohol in the present invention is preferably a linear or branched aliphatic alcohol having 1 to 6, preferably 1 to 4, more preferably 2 to 4 carbon atoms. Specific examples include methanol, ethanol, isopropanol, and tert-butanol. Of these, ethanol, isopropanol, and tertiary-butanol can achieve almost the same effect, but methanol has a slightly lower effect. Although the reason is not clear, it is presumed that the boiling point of the solvent, that is, the ease of flying during drying is related. Higher alcohols higher than that are not preferred because they have a high boiling point and are likely to remain after film formation.

  The amount of alcohol added must be carefully selected. These alcohols are completely poor in solubility in aromatic polycarbonate and are completely poor solvents. Therefore, it cannot be added too much, and should be the minimum amount that provides satisfactory peelability. As mentioned above, it is 4-14 mass parts with respect to a methylene chloride, Preferably it is 4-12 mass parts. When the addition amount is in the range of 4 to 14 parts by mass with respect to the amount of methylene chloride, the solubility of the solvent in the polymer and the dope stability are improved, and the effect of improving the peelability is increased.

  The present invention comprises the above methylene chloride and aliphatic alcohol in the dope composition, but other solvents can also be used. The remaining solvent is not particularly limited as long as it dissolves the aromatic polycarbonate at a high concentration and is compatible with alcohol, and further has a low boiling point. For example, as a solvent having a solubility in an aromatic polycarbonate, in addition to methylene chloride, halogen solvents such as chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, chlorobenzene, 1,3-dioxolane, 1, Examples include cyclic ether solvents such as 4-dioxane and tetrahydrofuran, and ketone solvents such as cyclohexanone.

  When using other solvent, there is no limitation in particular and it may use it in consideration of an effect. The effects here include mixing the solvent without sacrificing solubility and stability, for example, improving the surface properties of the film formed by the solution casting method (leveling effect), evaporation rate and system These include viscosity adjustment and crystallization suppression effects. What is necessary is just to determine the kind and addition amount of the solvent to mix by the degree of these effects, and you may use 1 type (s) or 2 or more types as a solvent to mix.

  Other solvents preferably used include halogen solvents such as chloroform and 1,2-dichloroethane, hydrocarbon solvents such as toluene and xylene, ketone solvents such as acetone, methyl ethyl ketone, and cyclohexanone, and ethyl acetate and butyl acetate. Examples include ester solvents, ether solvents such as ethylene glycol dimethyl ether and methoxyethyl acetate.

  The dope composition according to the present invention may be prepared by any method as long as a transparent solution having a low haze is obtained as a result. A predetermined amount of alcohol may be added to the aromatic polycarbonate solution dissolved in a certain solvent in advance, or the aromatic polycarbonate may be dissolved in a mixed solvent containing alcohol. However, as described above, since alcohol is a poor solvent, the method of adding the latter after the former may cause clouding of the dope due to the precipitation of the polymer. Therefore, the method of dissolving in the latter mixed solvent is preferable.

  In addition, it is obtained by reacting a dihydroxy component and a carbonate precursor by an interfacial polymerization method or a melt polymerization method. For example, those described in JP 2006-277914 A, JP 2006-106386 A, JP Those described in JP-A-2006-284703 can be preferably used. JP-A-8-54614, JP-A-8-54615, JP-A-8-62419, JP-A-8-160221, JP-A-8-160222, JP-A-9-222510, JP-A-10-111212, JP-A-10-231370, JP-A-10-23952, International Publication WO98 / 58789, JP-A-2002-328614, JP-A-2004-99754, and JP-A-2006-18956 can also be preferably used.

(D) Norbornene-based resin In the present invention, it is also preferable to use a cyclic olefin resin. Examples of the cyclic olefin resin include norbornene resins, monocyclic olefin resins, cyclic conjugated diene resins, vinyl alicyclic hydrocarbon resins, and hydrides thereof. Among these, norbornene-based resins can be suitably used because of their good transparency and moldability.

  Examples of the norbornene-based resin include a ring-opening polymer of a monomer having a norbornene structure, a ring-opening copolymer of a monomer having a norbornene structure and another monomer, a hydride thereof, and a norbornene structure. An addition polymer of a monomer having a monomer, an addition copolymer of a monomer having a norbornene structure and another monomer, or a hydride thereof.

  Among these, a ring-opening (co) polymer hydride of a monomer having a norbornene structure is particularly suitable from the viewpoints of transparency, moldability, heat resistance, low hygroscopicity, dimensional stability, lightness, and the like. Can be used.

  As a monomer having a norbornene structure, bicyclo [2.2.1] hept-2-ene (common name: norbornene), tricyclo [4.3.0.12,5] deca-3,7-diene ( Common name: dicyclopentadiene), 7,8-benzotricyclo [4.3.0.12,5] dec-3-ene (common name: methanotetrahydrofluorene), tetracyclo [4.4.0.12, 5.17,10] dodec-3-ene (common name: tetracyclododecene), and derivatives of these compounds (for example, those having a substituent in the ring). Here, examples of the substituent include an alkyl group, an alkylene group, and a polar group. Moreover, these substituents may be the same or different and a plurality may be bonded to the ring. Monomers having a norbornene structure can be used singly or in combination of two or more.

  Examples of the polar group include a hetero atom or an atomic group having a hetero atom. Examples of the hetero atom include an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, and a halogen atom. Specific examples of the polar group include a carboxyl group, a carbonyloxycarbonyl group, an epoxy group, a hydroxyl group, an oxy group, an ester group, a silanol group, a silyl group, an amino group, a nitrile group, and a sulfone group.

  Other monomers capable of ring-opening copolymerization with monomers having a norbornene structure include monocyclic olefins such as cyclohexene, cycloheptene, and cyclooctene and derivatives thereof, cyclic conjugated dienes such as cyclohexadiene, cycloheptadiene, and the like. And derivatives thereof.

  A ring-opening polymer of a monomer having a norbornene structure and a ring-opening copolymer of a monomer having a norbornene structure and another monomer copolymerizable with the monomer have a known ring-opening polymerization catalyst. It can be obtained by (co) polymerization in the presence.

  Examples of other monomers that can be addition copolymerized with a monomer having a norbornene structure include α-olefins having 2 to 20 carbon atoms such as ethylene, propylene, and 1-butene, and derivatives thereof; cyclobutene, cyclopentene, And cycloolefins such as cyclohexene and derivatives thereof; non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, and the like. These monomers can be used alone or in combination of two or more. Among these, α-olefin is preferable and ethylene is more preferable.

  An addition polymer of a monomer having a norbornene structure and an addition copolymer of a monomer having a norbornene structure with another monomer copolymerizable with a monomer having a norbornene structure are prepared in the presence of a known addition polymerization catalyst. It can be obtained by polymerization.

  A hydrogenated product of a ring-opening polymer of a monomer having a norbornene structure, a hydrogenated product of a ring-opening copolymer of a monomer having a norbornene structure and another monomer capable of ring-opening copolymerization thereof, Hydrogenated products of addition polymers of monomers having a norbornene structure, and hydrogenated products of addition copolymers of monomers having a norbornene structure and other monomers capable of addition copolymerization with these A known hydrogenation catalyst containing a transition metal such as nickel or palladium is added to the polymer solution, and the carbon-carbon unsaturated bond is preferably hydrogenated by 90% or more.

  Among norbornene resins, as a repeating unit, X: bicyclo [3.3.0] octane-2,4-diyl-ethylene structure and Y: tricyclo [4.3.0.12,5] decane-7, 9-diyl-ethylene structure, the content of these repeating units is 90% by mass or more based on the entire repeating unit of the norbornene resin, and the content ratio of X and the content ratio of Y The ratio is preferably a mass ratio of X: Y of 100: 0 to 40:60. By using such a resin, it is possible to obtain an optical compensation film (optical film) that has no dimensional change over a long period of time and is excellent in stability of optical characteristics.

  The molecular weight of the cyclic olefin resin used in the present invention is appropriately selected according to the purpose of use. Polyisoprene or polystyrene-converted weight average molecular weight (Mw) measured by gel permeation chromatography using cyclohexane (toluene if the polymer resin does not dissolve) as a solvent, usually 20,000 to 150,000. . Preferably it is 25,000-100,000, More preferably, it is 30,000-80,000. When the weight average molecular weight is in such a range, the mechanical strength and molding processability of the film are highly balanced and suitable.

  The glass transition temperature of the cyclic olefin resin may be appropriately selected according to the purpose of use. From the viewpoint of durability and stretchability, it is preferably in the range of 130 to 160 ° C, more preferably 135 to 150 ° C.

  The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the cyclic olefin resin is 1.2 to 3.5, preferably 1.5 to 3.0, from the viewpoint of relaxation time, productivity, and the like. More preferably, it is 1.8 to 2.7.

The cyclic olefin resin used in the present invention preferably has an absolute value of photoelastic coefficient of 10 × 10 ⁻¹² Pa ⁻¹ or less, more preferably 7 × 10 ⁻¹² Pa ⁻¹ or less, and more preferably 4 × 10. It is particularly preferably ⁻¹² Pa ⁻¹ or less. The photoelastic coefficient C is a value represented by C = Δn / σ where birefringence is Δn and stress is σ. If the photoelastic coefficient of the cyclic olefin resin exceeds 10 × 10 ⁻¹² Pa ⁻¹ , the in-plane retardation of the stretched film may vary widely.

The cyclic olefin-based resin is preferably polymerized from a norbornene-based compound, but this polymerization can be performed by either ring-opening polymerization or addition polymerization. Examples of the addition polymerization include those disclosed in Japanese Patent No. 3517471, Japanese Patent No. 3559360, Japanese Patent No. 3867178, Japanese Patent No. 3871721, Japanese Patent No. 3907908, Japanese Patent No. 3945598, Japanese Patent Publication No. 2005-527696, Japanese Patent Laid-Open No. 2006-28993, International Publication WO2006 / No. 004376 and those described in each publication. Particularly preferred is the one described in Japanese Patent No. 3517471.
Examples of the ring-opening polymerization include those described in International Publications WO 98/14499, Patent 30605532, Patent 3320478, Patent 373046, Patent 344027, Patent 3428176, Patent 3687231, Patent 3873934, and Patent 3912159. Can be mentioned. Of these, those described in International Publication Nos. WO98-14499 and Japanese Patent No. 30605532 are preferable.
JP-A-6-511117, JP-A-2002-114927, JP-A-2002-284971, JP-A-2003-238774, JP-A-2003-94464, JP-A-2004-133209, JP-A-2005-239740. JP-A-2006-77257, JP-A-2006-321912, JP-A-2007-106931, JP-A-2008-955, JP-A-2008-30243, JP-A-2008-37932, JP-A-2008-231361, JP 2008-238537 A and the like can also be used.
Of these cyclic olefins, addition polymerization is more preferable.

  In the present invention, it is preferable that the cyclic olefin resin does not substantially contain particles. Here, “substantially free of particles” means that even if particles are added to a film made of a cyclic olefin resin, the amount of haze increase from the non-added state is 0.05% or less. Means you can. In particular, the alicyclic polyolefin resin lacks affinity with many organic particles and inorganic particles. Therefore, when a cyclic olefin resin film to which particles exceeding the above range are added is stretched, voids are easily generated, and as a result, There is a risk that a significant decrease in haze occurs.

  In the present invention, by adding a load deflection temperature adjusting agent to the cyclic olefin resin, it is possible to obtain an optical compensation film having excellent stretchability as described above and improved changes in optical properties at high temperatures.

  This is because the difference between the glass transition temperature Tg (° C.) of the resin and the deflection temperature under load Tt (° C.) becomes large, so that the film can be stretched without applying excessive force even at low temperatures. It is considered that the unevenness of the retardation is greatly reduced and the thermal relaxation property of the retardation is improved.

  Specifically, the difference between Tg and Tt is Tg−Tt = 5 to 30 (° C.), more preferably 10 to 30 (° C.).

  Such cyclic olefin compounds include hydrocarbon solvents (C5-C12 linear, branched, cyclic saturated and unsaturated hydrocarbons), aromatic solvents (benzene, alkylbenzene (toluene, xylene, etc.), halogenated compounds. It can be dissolved in benzene (chlorobenzene, bromobenzene, etc.), chlorinated solvents (dichloromethane, chloroform, dichloroethane, trichloroethane, chlorobenzene, etc.), mixed solvents thereof and the like.

(E) Polystyrene resin A resin containing 20 mol% or more of polystyrene. In addition to polystyrene resin, copolymers such as acrylonitrile, butadiene, acrylic acid and methacrylic acid can also be used.

(F) Polyester resins For example, those disclosed in JP-T-2002-532593, JP-A-2006-231658, and JP-A-2006-264320 can be used.

(G) Vinyl alcohol resin (PVOH, EVOH, etc.)
Examples thereof include polyvinyl alcohols and ethylene-polyvinyl alcohol copolymers described in JP-A-5-337967, JP-A-2002-86476, and JP-A-2004-93906.

(H) Other resins Polyarylate and polysulfone described in JP-A-8-54613, polyethersulfone described in JP-A-8-253680 and JP-A-8-318538, JP 2002-519458 A Can be preferably used for polysulfone described in JP-A-2006-43907, maleimide resin described in JP-A-2006-43907, and the like.

<Additives>
The film of the present invention may contain a material other than the above resin, but it contains one or more of the above resins as a main component (meaning the material having the highest content ratio among all the materials in the composition). In an embodiment containing two or more kinds of the resins, it means that the total content ratio thereof is higher than the content ratios of the other materials. Examples of materials other than the above resins include various additives. Examples thereof include antioxidants, acid scavengers, stabilizers, ultraviolet absorbers, light stabilizers, plasticizers, fine particles, and antistatic agents. , Release agents, optical anisotropy control agents, and optical adjusting agents.

  The film of the present invention contains an additive, and the concentration of the additive is preferably uniform in the film thickness direction. The reason is that the resin is preferably uniform.

(1) Optical modifier Among the additives, it is an optical anisotropy control agent that effectively contributes to the present invention, and in particular, the retardation increasing agent optically birefringence obliquely from the plane of the present application. This is preferable because it easily develops in the direction. The retardation increasing agent is preferably an aromatic compound having at least two aromatic rings. The aromatic compound is preferably used in the range of 0.01 to 20 parts by mass with respect to 100 parts by mass of the resin. And it is preferable to use in 0.05-15 mass parts, and it is still more preferable to use in 0.1-10 mass parts. Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound includes an aromatic hetero ring in addition to the aromatic hydrocarbon ring. The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring). The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring. Details thereof are described in JP-A No. 2004-109410, JP-A No. 2003-344655, JP-A No. 2000-275434, JP-A No. 2000-1111914, JP-A No. 12-275434, and the like.
In the preferable aspect of this invention, it is preferable that the film of this invention contains 1-30 mass% optical adjusting agent with respect to resin. Examples thereof include compounds having two or more aromatic rings in one molecule, porphyrin compounds, and the like, and Re and Rth can be adjusted.

In addition to the above, the following optical adjusting agents can be used.
Examples of the optical tone adjusting agent include compounds containing two or more aromatic rings shown below.
The compound described in [Chemical Formula 1] described in Japanese Patent No. 3155465.
The compound described in [Chemical Formula 1] described in Japanese Patent No. 4084519.
Compounds of [Chemical Formula 1] to [Chemical Formula 9] described in Japanese Patent No. 3734211.
Compounds of [Chemical Formula 1] to [Chemical Formula 7] described in JP-A No. 2006-176736.
Compounds of [Chemical Formula 1] to [Chemical Formula 3] described in JP-A-2008-79548.
Compounds of [Chemical Formula 1] to [Chemical Formula 163] described in JP-A-9-21914.
Besides these, for example, those described in JP-A Nos. 2001-166144, 2003-344655, 2003-248117, and 2003-66230 can be used. By adding an optical adjusting agent, in-plane retardation (Re) and thickness direction retardation (Rth) can be controlled. These may be used alone or in combination.
JP-A 2000-1111914, 2000-275434, 2001-100039, 2001-166144, 2002-71948, 2002-267838, 2002-303722, 2003-43250, 2003-344660, 2003-344655, 2004-4550, 2004-10663, 2004-51562, 2004-51563, 2004-53840, 2004-53841, 2004 109410, 2005-338744, 2006-8944, 2006-63266, 2006-89691, 2006-91527, 2006-98592, 2006-117908, 2006-1196 No. 2, No. 2006-188718, No. 2006-265288, No. 2006-265382, No. 2006-267171, No. 2006-292890, No. 2006-292895, No. 2006-323329, No. 2006-335800 No. 2006-342226, No. 2007-31701, No. 2007-52109, No. 2007-71974, No. 2007-144932, Special Table No. 2007-517234, JP 2007-197508, No. 2007-248620. 2007-262153, 2007-291216, 2007-297554, JP 2008-505195, JP 2008-120087, JP 2008-120875, 2008-150592, 2008. No. 217,022, the 2008-233814 Patent, the 2008-255340 Patent, it attempts to preferably be optical modifier according to the 2005-104148 Patent JP-like.
These optical adjusting agents are preferably 0% by mass to 30% by mass with respect to the resin, more preferably 0% by mass to 25% by mass, and still more preferably 0% by mass to 20% by mass. Within these ranges, Re [0 °], Rth, and γ of the film of the present invention can be controlled within a preferable range.

(2) Stabilizer:
The film of the present invention may contain at least one stabilizer. The stabilizer is preferably added before adjusting the dope containing the resin or at the time of preparing the dope. The stabilizer has effects such as preventing oxidation of the film constituting material, capturing an acid generated by decomposition, and suppressing or inhibiting a decomposition reaction caused by radical species caused by light or heat. Stabilizers are useful for suppressing the occurrence of alterations such as coloring and molecular weight reduction and the generation of volatile components due to various decomposition reactions including unresolved decomposition reactions. The stabilizer itself is required to function without being decomposed even at the film forming temperature when forming the resin. Typical examples of stabilizers include phenol-based stabilizers, phosphorous acid-based stabilizers (phosphite-based), thioether-based stabilizers, amine-based stabilizers, epoxy-based stabilizers, and lactone-based stabilizers. Stabilizers, amine stabilizers, metal deactivators (tin stabilizers) and the like are included. These are described in JP-A-3-199201, JP-A-5-1907073, JP-A-5-194789, JP-A-5-271471, JP-A-6-107854, and the like. Then, it is preferable to use at least one or more of a phenol-based or phosphorous acid-based stabilizer. Among phenolic stabilizers, it is particularly preferable to add a phenolic stabilizer having a molecular weight of 500 or more. Preferable phenolic stabilizers include hindered phenolic stabilizers.

  These materials are readily available as commercial products and are sold by the following manufacturers. From Ciba Specialty Chemicals, Irganox 1076, Irganox 1010, Irganox 3113, Irganox 245, Irganox 1135, Irganox 1330, Irganox 259, Irganox 565, Irganx 565, Irganx 565, Ir35x10 Moreover, it can obtain from Asahi Denka Kogyo Co., Ltd. as ADK STAB AO-50, ADK STAB AO-60, ADK STAB AO-20, ADK STAB AO-70, and ADK STAB AO-80. Furthermore, from Sumitomo Chemical Co., Ltd., it can obtain as Sumilizer BP-76, Sumilizer BP-101, Sumilizer GA-80. In addition, it is also possible to obtain as Sinox 326M and Sinox 336B from Sipro Kasei Co., Ltd.

  Moreover, as said phosphorous acid type stabilizer, the compound as described in [0023]-[0039] of Unexamined-Japanese-Patent No. 2004-182979 can be used more preferably. Specific examples of the phosphite ester stabilizer include JP-A-51-70316, JP-A-10-306175, JP-A-57-78431, JP-A-54-157159, Examples thereof include compounds described in Japanese Utility Model Laid-Open No. 55-13765. Furthermore, as other stabilizers, the materials described in detail on pages 17 to 22 of the Japan Institute of Invention Disclosure Bulletin (Public Technical No. 2001-1745, issued March 15, 2001, Japan Society of Invention) are preferably used. be able to.

  The phosphite stabilizer is useful to have a high molecular weight in order to maintain stability at high temperature, has a molecular weight of 500 or more, more preferably a molecular weight of 550 or more, and particularly a molecular weight of 600 or more. Is preferred. Furthermore, at least one substituent is preferably an aromatic ester group. The phosphite ester stabilizer is preferably a triester, and is desirably free of impurities such as phosphoric acid, monoester and diester. When these impurities are present, the content is preferably 5% by mass or less, more preferably 3% by mass or less, and particularly 2% by mass or less. These include compounds described in [0023] to [0039] of JP-A No. 2004-182979, JP-A-51-70316, JP-A-10-306175, JP-A-57. The compounds described in JP-A-78431, JP-A-54-157159, and JP-A-55-13765 can also be mentioned. Preferred specific examples of the phosphite stabilizer include the following compounds, but the phosphite stabilizer that can be used in the present invention is not limited thereto.

  These are commercially available from Asahi Denka Kogyo Co., Ltd. as ADK STAB 1178, 2112, PEP-8, PEP-24G, PEP-36G, and HP-10, and Sandostab P-EPQ from Clariant. Is possible. Furthermore, a stabilizer having phenol and phosphite in the same molecule is also preferably used. These compounds are further described in detail in JP-A-10-273494. Examples of the compounds are included in the examples of the stabilizer, but are not limited thereto. As a typical commercial product, Sumitizer GP is available from Sumitomo Chemical Co., Ltd. These are commercially available from Sumitomo Chemical Co., Ltd. as Sumilizer TPL, TPM, TPS, TDP. It is also available from Asahi Denka Kogyo Co., Ltd. as ADK STAB AO-412S.

  The stabilizers can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within a range not impairing the object of the present invention. Preferably, the addition amount of the stabilizer is preferably 0.001 to 5% by mass, more preferably 0.005 to 3% by mass, and still more preferably 0.01 to 0.8% with respect to the mass of the resin. % By mass.

UV absorber:
The film of the present invention may contain one type or two or more types of ultraviolet absorbers. From the viewpoint of preventing deterioration, the ultraviolet absorbent is preferably excellent in the ability to absorb ultraviolet light having a wavelength of 380 nm or less and has little absorption of visible light having a wavelength of 400 nm or more from the viewpoint of transparency. Examples include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. Particularly preferred ultraviolet absorbers are benzotriazole compounds and benzophenone compounds. Among these, a benzotriazole-based compound is preferable because unnecessary coloring with respect to the cellulose mixed ester is small. These are disclosed in JP-A-60-235852, JP-A-3-199201, 5-1907073, 5-194789, 5-271471, 6-107854, 6-118233, 6 -148430, 7-11056, 7-11055, 7-11056, 8-29619, 8-239509, and JP-A-2000-204173.
The addition amount of the ultraviolet absorber is preferably 0.01-2% by mass of the resin, and more preferably 0.01-1.5% by mass.

Light stabilizer:
The film of the present invention may contain one or more light stabilizers. Light stabilizers include hindered amine light stabilizer (HALS) compounds, more specifically, US Pat. No. 4,619,956, columns 5-11 and US Pat. No. 4,839. 2,405, 2,2,6,6-tetraalkylpiperidine compounds, or their acid addition salts or complexes of them with metal compounds. These are commercially available from Asahi Denka as ADK STAB LA-57, LA-52, LA-67, LA-62, LA-77, and TINUVIN 765, 144 from Ciba Specialty Chemicals. .

  These hindered amine light stabilizers can be used alone or in combination of two or more. These hindered amine light stabilizers may of course be used in combination with additives such as plasticizers, stabilizers, UV absorbers, etc., or may be introduced into a part of the molecular structure of these additives. Good. The blending amount is determined within a range not impairing the effects of the present invention, and is generally about 0.01 to 20 parts by mass, preferably 0.02 to 15 parts by mass with respect to 100 parts by mass of the resin. The degree, particularly preferably about 0.05 to 10 parts by mass. The light stabilizer may be added at any stage of preparing the dope containing the resin composition, for example, at the end of the dope preparation process.

(3) Plasticizer:
The film of the present invention may contain a plasticizer. The addition of a plasticizer is preferable from the viewpoint of film modification such as improvement of mechanical properties, imparting flexibility, imparting water absorption resistance, and reducing moisture permeability. In addition, when the film of the present invention is produced by a melt film-forming method, the purpose is to lower the melting temperature of the film constituting material by adding a plasticizer rather than the glass transition temperature of the thermoplastic resin to be used, or no addition Will be added for the purpose of lowering the viscosity at the same heating temperature than the other thermoplastic resins. For the film of the present invention, for example, a plasticizer selected from phosphoric acid ester derivatives and carboxylic acid ester derivatives is preferably used. Further, a polymer obtained by polymerizing an ethylenically unsaturated monomer having a weight average molecular weight of 500 to 10,000 described in JP-A-2003-12859, an acrylic polymer, an acrylic polymer having an aromatic ring in the side chain, or cyclohexyl An acrylic polymer having a group in the side chain is also preferably used.
For example, JP 2001-19776, JP 2001-206981, JP 2002-103358, JP 2002-128903, JP 2003-1652, JP 2003-33998, JP 2003-114333. JP, 2004-314529, JP, 2005-40999, JP, 2005-62594, JP, 2005-104148, JP, 2005-148110, JP, 2005-148519, JP, 2005-156615, JP2005-157038, JP2005-165171, JP2005-246797, JP2005-530865, JP2006-116788, JP2006-232892, JP2006-233043, JP2006 No. 257380, JP 2006-2 No. 9494, JP 2006-330087, JP 2007-112870, JP 2007-216600, or the like can be used also preferably each JP 2007-254699. JP-A-10-160934, JP-T-2005-515285, JP-A-2005-88578, JP-A-2006-117714, JP-A-2006-232892, JP-A-2006-301292, JP-A-2006-328298, JP 2007-63310, JP 2007-231157, JP 2007-284570, JP 2007-293295, JP 2007-313754, JP 2008-80651, JP 2008-257220 The plasticizers described in the above can also be preferably used.

(4) Fine particles:
In the optical film of the present invention, it is preferable to add fine particles as a matting agent in order to prevent the produced film from being scratched or having poor transportability when handled.

  As fine particles, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, Examples thereof include magnesium silicate and calcium phosphate. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable.

  The average primary particle diameter of the fine particles is preferably 5 to 400 nm, and more preferably 10 to 300 nm. These may be mainly contained as secondary aggregates having a particle size of 0.05 to 0.3 μm, and may be contained as primary particles without being aggregated if the particles have an average particle size of 100 to 400 nm. preferable. The content of these fine particles in the optical film is preferably 0.01 to 1% by mass, particularly preferably 0.05 to 0.5% by mass. In the case of an optical film having a multilayer structure by the co-casting method, it is preferable to contain fine particles of this addition amount on the surface.

  Silicon dioxide fine particles are commercially available, for example, under the trade names Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.). it can.

    Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

  Examples of the polymer include silicone resin, fluororesin, and acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.) It is marketed by name and can be used.

  Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large effect of reducing the friction coefficient while keeping the haze of the optical film low. In the optical film of the present invention, it is preferable that the dynamic friction coefficient of at least one surface is 0.2 to 1.0.

<Second Embodiment (Stretched and Shrinked perpendicular to the direction of stretching)>
The film of the present invention may be shrunk perpendicular to the stretching and stretching directions even if it is not shrunk perpendicular to the stretching and stretching directions. Due to such a difference in aspect, the film of the second aspect of the present invention is characterized in that the distribution of γ is 1 to 30 nm. Furthermore, optical characteristics such as in-plane retardation Re and thickness-direction retardation Rth can be controlled. On the other hand, in the case of the second embodiment in which the film of the present invention is contracted in the direction orthogonal to the stretching direction, the above-mentioned extinction position, residual solvent amount, circular retardance, and other additives, film thickness, surface roughness The preferred ranges such as are the same as those in the first embodiment (an embodiment in which the film is not stretched and contracted perpendicular to the stretching direction).
The film of the second aspect of the present invention can provide an optical film that is less likely to cause wrinkles by heat treatment or the like by taking the above-described configuration. Furthermore, it is preferable to provide a film with improved optical unevenness according to the second aspect of the present invention. Hereinafter, the optical characteristics of the film of the second embodiment that has been stretched and contracted perpendicular to the stretching direction will be described.

(Gamma distribution)
In the film of the second aspect of the present invention, the distribution of γ represented by the following formula (VI) is 1 to 30 nm.
γ distribution = maximum value of γ measured in the width direction−minimum value of γ measured in the width direction (VI)
γ = | Re [+ 40 °] −Re [−40 °] | (VI) ′
(In the formula (VI) ′, Re [+ 40 °] is an in-plane at a wavelength of 550 nm measured from a direction inclined to the tilt azimuth side by 40 ° with respect to the normal in a plane including the film tilt azimuth and film normal. (Re [−40 °] represents the retardation in the in-plane direction at a wavelength of 550 nm measured from the direction inclined by −40 ° to the tilt direction with respect to the normal line.)
The structure of the extinction angle due to the pinching pressure under the specific conditions of the present invention appears along the film forming direction (MD). At this time, a portion having a large extinction angle and a portion having a small extinction angle are generated. The portion having a small extinction angle has a small molecular orientation, and even the slight clamping pressure easily changes the extinction angle, resulting in optical nonuniformity. On the other hand, the film having a small molecular orientation stretched and further contracted perpendicular to the stretching direction is further free from optical unevenness.
Specifically, in the film of the second aspect of the present invention, after performing “semi-fluid clamping pressure” and “lateral stretching with longitudinal shrinkage” (after film formation, stretching and longitudinal shrinkage are all completed) By controlling the amount of residual solvent in the specific range, the distribution in the width direction of optical characteristics (extinction angle) can be improved. First, residual stress is developed in the film by “semi-fluid clamping pressure” and “lateral stretching with longitudinal shrinkage”. Residual strain due to residual stress often appears locally, and this causes the generation of wrinkles during heat treatment and disturbs the molecular orientation in the film surface, so that the optical properties (γ, Re [0 °], Rth) It causes distribution (unevenness).
On the other hand, by causing the solvent to remain in the film so as to be in the range of the residual solvent amount of the present invention described in the first aspect, the effect of promoting the flow of molecules in the film and eliminating the residual strain is achieved. Play. As a result, wrinkles and optical unevenness are reduced. By setting the residual solvent amount within the range of the present invention, these unevennesses can be reduced. However, if the residual solvent amount is less than or equal to the upper limit of the range of the present invention, it is difficult for the molecules to flow due to the residual solvent, and the occurrence of uneven alignment can be suppressed. As a result, the distribution of γ can be controlled within the range of the second aspect of the present invention. In addition, shrinkage hardly occurs when the solvent dries, it becomes difficult to become wrinkles in heat treatment, and it is possible to suppress the occurrence of residual stress in the film surface or increase in unevenness due to drying shrinkage. it can. On the other hand, when the residual solvent is not less than the lower limit of the range of the present invention, the above-described residual strain relaxation effect can be sufficiently exerted, and unevenness and wrinkles are hardly generated.
Controlling the amount of residual solvent within a specific range is also effective in improving unevenness and wrinkles, but it is also possible to perform stretching with pinching and longitudinal shrinkage in the second aspect of the present invention described later. It is effective for improvement. In the second aspect of the present invention, it is possible to provide a film that exhibits a synergistic effect by combining these, and can obtain a more remarkable effect.

(Slow axis)
The film of the second aspect of the present invention preferably has a slow axis in the width direction. That is, in the film manufacturing method of the second aspect of the present invention described later, the film is preferably a film obtained as a direction (film width direction) in which the stretching direction is orthogonal to the film transport direction.

(Re, Rth)
The film of the second aspect of the present invention preferably satisfies the following formulas (VII) and (VIII).
0 nm ≦ Re [0 °] ≦ 200 nm (VII) Formula −50 nm ≦ Rth ≦ 300 nm (VIII) Formula (In the formula (VII), Re [0 °] is the plane including the film tilt direction and the film normal. Represents in-plane retardation at a wavelength of 550 nm measured from the normal direction.)
More preferably 20 nm ≦ Re [0 °] ≦ 100 nm (VII) ′ formula −30 nm ≦ Rth ≦ 200 nm (VIII) ′ formula More preferably 30 nm ≦ Re [0 °] ≦ 100 nm (VII) ″ formula −20 nm ≦ Rth ≦ 150 nm (VIII) ″ formula.
By setting it in such a range, it can be effectively operated as an optical compensation film of a liquid crystal display panel and a λ / 4 wavelength plate of an organic EL display panel. A positive birefringent resin is preferably used in a region where Rth is positive, and examples thereof include a cycloolefin resin, a polycarbonate resin, a polyester resin, a polyolefin resin, and a polyvinyl alcohol resin. On the other hand, a negative birefringent resin may be used in a region where Rth is negative, and examples thereof include acrylic and polystyrene resins. Cellulose acylate resins can generally be classified as positive birefringent resins. However, if the degree of acyl substitution is increased and crystallization is advanced, negative birefringence is exhibited as described in JP-A-2007-249197. be able to.

The film of the second aspect of the present invention preferably satisfies the following formula (IX).
30 nm ≦ γ ≦ 200 nm (IX) formula γ = | Re [+ 40 °] −Re [−40 °] | (IX) ′ formula (in the formula (IX) ′, Re [+ 40 °] is the film tilt direction and the film method. In the plane including the line, it represents retardation in the in-plane direction at a wavelength of 550 nm measured from a direction inclined to the tilt azimuth side by 40 ° with respect to the normal, and Re [−40 °] is relative to the normal Represents retardation in the in-plane direction at a wavelength of 550 nm measured from a direction tilted by −40 ° toward the tilt direction.)
More preferably, 50 nm ≦ γ ≦ 150 nm (IX-2), and still more preferably 70 nm ≦ γ ≦ 100 nm (IX-3).

[Film Production Method]
<< Film Formation Method >>
<The manufacturing method of the 1st aspect (the film which is not contracted orthogonally to extending | stretching and an extending | stretching direction)>
First, the manufacturing method of the film of the 1st aspect of this invention is demonstrated.

(Solution casting)
The film production method of the present invention (hereinafter also referred to as the production method of the present invention) is a step of extruding a dope (high concentration resin solution) containing a resin and a solvent from a supply means (for example, a die) as a semi-fluid film. A step of casting the extruded semi-fluid film on the support, a step of peeling the cast semi-fluid film from the support, a step of drying the peeled semi-fluid film, and a residual solvent amount. The step of controlling to 0.01 to 3% by mass, and the semi-fluid film having a viscosity of 1 Pa · s to 100,000 Pa · s between the first clamping surface and the second clamping surface constituting the clamping device is 20 MPa to It is characterized by including a step of continuously clamping by passing while applying a clamping pressure of 500 MPa.
In the present specification, the semi-fluid film refers to a film between a liquid and a solid film from extrusion to drying. In the production method of the present invention, such a film is formed by forming a nipping device in a solution casting method in which a dope (a concentrated solution of a polymer) is extruded from a die, cast onto a support, peeled off, and dried. A film between a liquid and a solid film between extrusion and drying while applying a clamping pressure of 20 MPa to 500 MPa between the one clamping surface and the second clamping surface (referred to as “semi-fluid film” in the present invention). The film has a viscosity of 1 Pa · s to 100,000 Pa · s, more preferably 3 Pa · s to 70,000 Pa · s, and still more preferably 5 Pa · s to 50,000 Pa · s, and the film is continuously pinched and pressed. It is preferable to form it into a shape. The viscosity referred to here is a shear rate = 1 sec−1, and is a value measured by the composition (solvent content) and temperature at the point of clamping. Moreover, in the manufacturing method of this invention, the said pinching process may be implemented in any place even if it implements at any time between an extrusion process and a drying process.

Since such a longitudinal stretching method only provides a clamping step during the film forming process, the equipment is more compact than conventional longitudinal stretching equipment (using a heating device and a plurality of pairs of nip rolls). It can be easily installed in a film forming apparatus. There is also an advantage that the equipment cost can be reduced.
The flow rate required for the present invention can be achieved by not lowering the range of the above-mentioned clamping pressure. On the other hand, by not exceeding the range of the clamping pressure, it can be suppressed that the structure in which the extinction position differs depending on the distance from the thickness direction from one end of the film is eliminated.
By ensuring that the fluidity of the semi-fluid film does not exceed the above-mentioned range, the viscosity of the semi-fluid film at the time of clamping is assured, and a structure having extinction positions at different angles due to stretching deformation and shear stress as described above. Can be formed. Furthermore, by not falling below the above range, orientation relaxation (the structure in which the extinction position in the semi-fluid film once oriented due to too high fluidity varies depending on the distance from the thickness direction from one end of the film disappears. Can be suppressed. That is, by setting the viscosity in such a range, it is possible to easily form a structure in which the extinction position differs depending on the distance from the thickness direction from one end of the film.
Hereinafter, the preferable aspect of the manufacturing method of this invention is demonstrated.

As each of these steps, a known solution casting method can be used as long as it is not contrary to the gist of the present invention. For example, in the production method of the present invention, the resin is dried and then mixed with a solvent, and a concentrated solution (dope) of preferably 5 to 40% by mass, more preferably 10 to 35% by mass is formed. It is also preferable to add the above additives in addition to the resin. This is preferably filtered and defoamed and then cast on a support such as a drum or a band. At this time, it is also preferable to prepare a multilayer film using a co-casting die or the like. At this time, as described above, it is preferable to perform a pressure-clamping process between the support and the drying zone, and more preferably, after peeling from the support until drying.
Specifically, JP-A 2000-84960, JP-A 2003-53749, JP-A 2004-66683, JP-A 2004-322535, JP-A 2006-283013, JP-A 2007-79561, JP-A 2007-. 178504, JP-A-2005-104148, JP-A-61-94724, JP-A-62-46625, JP-A-3-193316, JP-B-6-27206, JP-B-7-106603, JP-A-2554553 , Patent 2630535, Patent 2950709, Patent 3220478, Patent 3295238, Patent 3326607, Patent 3329154, Patent 3355986, Patent 3403882, Patent 3351007, Patent 3531835, Patent 3537918, Patent 3628933, Patent 363 No. 494, Japanese Patent No. 3674284, Japanese Patent No. 3742025, Japanese Patent No. 3765765, Japanese Patent No. 3815912, Japanese Patent No. 3830559, Japanese Patent No. 3879920, Japanese Patent No. 3893862, Japanese Patent No. 3903100, Japanese Patent No. 3931514, Japanese Patent No. 3931855, Japanese Patent No. 3946533 Patent No. 3970022, Patent No. 3974422, Patent No. 3978862, Patent No. 3994244, Patent No. 4013568, Patent No. 4017139, Patent No. 4019855, Patent No. 4032771, Patent No. 4089944, Patent No. 4059730, Patent No. 40844431, Patent No. 4088119, Patent No. 4088128, Japanese Patent No. 4109824, Japanese Patent No. 4141232, Japanese Patent No. 4128327, Japanese Patent No. 4169183, Japanese Patent No. 417599 JP, 2005-96474, JP 2005-103815, JP 2005-156682, JP 2005-181683, JP 2005-181747, JP 2005-186289, JP 2005-231185. JP, 2005-271233, JP, 2006-95971, JP, 2006-116788, JP, 2006-160863, JP, 2006-199029, JP, 2006-208516, JP, 2006-256184, JP, 2006-315417, JP, 2007-15395, JP, 2007-42594, JP, 2007-45071, JP, 2007-62064, JP, 2007-93897, JP, 2007-99855, Special No. 2007-125896, JP 2007-12 6571, JP 2007-249094, JP 2007-253499, JP 2008-80552, JP 2008-88221, JP 2008-1111084, JP 2008-194928, JP 2008-201440. JP, JP-A-2008-265271, JP-A-2008-268918, JP-A-11216732, JP-A-2001-113544, JP-A-2002-79534, JP-A-2002-103357, JP-A-2002-103358, Special JP 2002-144357, JP 2002-316331, JP 2003-53750, JP 2003-20045, JP 2003-200478, JP 2003-236862, JP 2004-66613, JP Made of 2004-107629 Law can be preferably used.

<Preparation of dope>
First, the resin is dissolved in the solvent to prepare a dope. At that time, the temperature may be raised or cooled, or a combination thereof may be carried out. Unused resin may be used, what was used once may be reused, and these may be mixed and used. The mixing ratio at this time is preferably 5 to 50% by weight, more preferably 10 to 40% by weight of the reuse resin. Furthermore, it is also preferable to add said additive.

  In the production method of the present invention, the viscosity of the semi-fluid film in the pinching step can be controlled within the range of the present invention by adjusting the dope viscosity at the time of preparation. The dope viscosity at the time of preparation can be adjusted by the concentration of the resin and additives added to the dope, the molecular weight of the resin, and the like. The dope viscosity at the time of the preparation is preferably 5 to 40% by mass, more preferably 10 to 35% by mass with respect to the total dope amount.

<Extrusion>
It is preferable that the dope dissolved in this manner is filtered and defoamed and then continuously fed to a supply means (preferably a die) via a pump. The die may be any of a T die, a fish tail die, and a hanger coat die. Further, a multi-manifold die or a feed block die may be used for lamination. It is also preferable to place a static mixer in front of the die to promote resin mixing.

The clearance of the outlet portion of the supply means (for example, die) is generally 5 to 50 times the film thickness, preferably 7 to 40 times. Specifically, it is preferably 0.2 to 10 mm, more preferably 0.3 to 5 mm, and particularly preferably 0.5 to 3 mm.
In the manufacturing method of the present invention, the radius of curvature of the tip of the die lip is not particularly limited, and a known die can be used.

  It is preferable that the die can be adjusted in thickness at intervals of 5 to 50 mm. An automatic thickness adjustment die that calculates downstream film thickness and thickness deviation and feeds back the results to die thickness adjustment is also effective.

  The dope is cast on a support through a supply means (for example, a die). At this time, the dope may be cast in a single layer or in multiple layers. For multi-layer casting, a feed block die or a multi-manifold die can be used. Furthermore, it is also preferable to further increase the number of layers by combining with a static mixer. The number of layers is preferably 1 to 300 layers, more preferably 1 to 100 layers, and still more preferably 1 to 10 layers.

<Clamping process>
The production method of the present invention is characterized in that a semi-fluid film containing a solvent is sandwiched between the first sandwiching surface and the second sandwiching surface, and in the presence of residual solvent, before peeling from the support, or This can be done after stripping. The clamping pressure of the semi-fluid film by such a clamping apparatus is obtained by extruding the prepared dope from the supply means (for example, die) toward the support as a semi-fluid film, while the semi-fluid film has fluidity. Need to be done. That is, the semi-fluid film is allowed to pass between the first clamping surface and the second clamping surface before being dried to become a solid film.

(Pinch area)
The clamping step may be performed anywhere as long as the semi-fluid film has a viscosity within the range of the present invention. First, the dope is cast on a support and then peeled off from the support while being dried. Thereafter, it is preferably led to the drying zone. In the production method of the present invention, the structure in which the extinction position varies depending on the distance in the thickness direction from one end of the film can be easily formed by giving the semi-fluid film the deformation due to the pinching body in the flow state before drying. It is preferable to do. That is, it is preferably carried out from the supply means (for example, die) outlet to the drying zone, more preferably from the supply means (for example, die) outlet to the support, and further preferably the supply means (for example, die) outlet. To the support. For example, (1) a pair of pinching bodies (roll or belt) may be installed between the supply means (for example, die) and the support, and (2) the pinching body on the support (band or drum). (In this case, the support is used as one clamping body) (3) After peeling off from the support, a pair of clamping bodies (roll or belt) is installed. May be installed. Among these, it is particularly preferable to use (1). In the case of (1), the support or the casing of the support is cooled, and the semifluid film temperature is cooled to 10 ° C. or lower and −50 ° C. or higher. Thus, the “structure in which the extinction position differs depending on the distance in the thickness direction from one end of the film” formed by the pinching body can be fixed, which is more preferable. This is because by cooling the semi-fluid film, the elasticity of the semi-fluid film can be increased and further deformation (molecular orientation) can be promoted. In the present invention, the drying zone refers to a region of 100 ° C. or higher where the solvent in the film is 30% by mass or less based on the solid content.

(Clamping device)
Examples of the clamping device having different speeds on the first clamping surface and the second clamping surface include, for example, a combination of two rolls, and a combination of a roll and a touch belt described in JP 2000-219752 A (single-sided belt method). Or a combination of belts (double-sided belt method). Among these, two rolls are preferable because the pressure can be applied uniformly.
The pinching pressure can be measured by passing a pressure measurement film (such as a prescale for medium pressure manufactured by Fuji Film) through two pinching bodies. The preferable range of the clamping pressure is the same as the preferable range of the pressure for clamping the semi-fluid film between the clamping surfaces of the clamping device in the description of the clamping device.

In the production method of the present invention, it is preferable to apply a pressure of 20 MPa to 500 MPa between the clamping devices, more preferably 30 to 300 MPa, and still more preferably 40 to 200 MPa. By applying pressure in this manner, molecular orientation is promoted by the effects described above, and birefringence is exhibited.
The pressure between the clamping devices can be measured by passing a pressure measurement film (such as a prescale for medium pressure manufactured by Fuji Film) between the clamping devices.

In the manufacturing method of the present invention, the moving speed of the first clamping surface may be equal to the moving speed of the second clamping surface, or one of them may be increased. In the production method of the present invention, it is preferable to provide a moving speed difference in order to express the γ. In that case, the first pressing surface of the pressing apparatus defined by the following formula (V) (the one with the higher moving speed) It is preferable to control so that the movement speed difference between the second clamping surface and the second clamping surface (the one with the slower movement speed) is 0.5 to 20%.
Formula (V)
Difference in moving speed (%) = 100 × {(moving speed of first pressing surface) − (moving speed of second pressing surface)}
/ (Moving speed of the first clamping surface)
Thereby, it is possible to promote molecular orientation oblique to the MD direction in the melt or dope. The movement speed difference is preferably 0% to 20%, more preferably 0% to 15%, and still more preferably 0% to 10%. At this time, the moving speed on the low speed side is preferably 10 m / min to 300 m / min, more preferably 20 m / min to 250 m / min, and further preferably 30 m / min to 200 m / min.
At this time, either one of the first clamping surface and the second clamping surface is peeled off first from the semi-fluid film, and then the other surface and the semi-fluid film are peeled off to stabilize the productivity. It is preferable from the viewpoint. In the manufacturing method of the present invention, it is preferable that the moving speed of the first pressing surface is higher than the moving speed of the second pressing surface. However, even if the surface to be peeled first is the first pressing surface, It may be a pressure side. From the viewpoint of suppressing the peeling dan, it is preferable that the surface to be peeled first is the first clamping surface (a clamping surface having a high moving speed).

  In the manufacturing method of the present invention, the two pinching bodies may be driven or driven independently, but in order to suppress variations in Re [0 °] and γ, it is preferable that they are driven independently.

(Viscosity of semi-fluid film)
In the production method of the present invention, it is preferable to adjust the temperature of the semifluid film between the dissolution of the dope and before the pinching from the viewpoint of setting the viscosity of the semifluid film during the pinching within the range of the present invention. It may be achieved by heating and cooling the dope to be cast, or by adjusting the temperature of the support on the cast support or by adjusting the temperature in the casing of the support. The temperature at this time is preferably −50 ° C. to less than 100 ° C., more preferably −30 ° C. to 80 ° C.
Moreover, the viscosity of the semi-fluid film at the time of clamping can be controlled by adjusting the composition of the dope at the time of preparation and / or adjusting the temperature of the semi-fluid film from the dissolution of the dope to before the clamping. It is more preferable to adjust the composition of the dope at the time and to adjust the temperature of the semi-fluid film between the dissolution of the dope and before the clamping. It is particularly preferable to control the temperature adjustment according to the adjustment of the composition of the dope at the time of preparation. It is particularly preferable to control the viscosity of the semi-fluid film by measuring in advance the temperature within the viscosity range of the present invention from the composition of the dope at the time of preparation and adjusting the temperature of the semi-fluid film. In addition, when using a dope containing a resin, a solvent, or an additive used in a preferred embodiment of the present invention, for example, a semi-fluid film having a solvent amount of 30% by mass to 1000% by mass relative to the solid content is included in the production method of the present invention. Since the viscosity is controlled, it is also preferable to sandwich a semi-fluid film having a solvent amount of 30% by mass to 1000% by mass with respect to the solid content.

Further, in the production method of the present invention, it is particularly preferable to adjust the temperature by the sandwiching body itself from the viewpoint of setting the temperature of the semifluid film to the above preferable range and setting the viscosity of the semifluid film to the range of the present invention. This is because the clamping body directly contacts the semi-fluid film and exchanges heat, so that the temperature of the semi-fluid film during clamping can be accurately controlled. That is, the temperature of the pinching body is approximately the temperature of the semi-fluid film at the time of pinching. Such a temperature control of the pinching body is preferably a method of circulating a heat medium in the pinching body. The temperature of the pinching body, that is, the temperature of the semi-fluid film at the time of pinching is preferably −50 ° C. to 99 ° C., more preferably −30 ° C. to 80 ° C., and further preferably −20 ° C. to 60 ° C.
Furthermore, you may make a difference in the surface temperature of two pinching bodies. A preferable temperature difference is 0 ° C. to 30 ° C., more preferably 0 ° C. to 20 ° C., and further preferably 0 ° C. to 10 ° C. In that case, the temperature of two rolls is set to -50 degreeC to 50 degreeC. This temperature difference may cause either of the nipping surfaces to be at a high temperature, thereby making the tilted orientation stronger. Such temperature control can be achieved by heating and cooling the pinching body with an external heat source and cooling source even by passing a temperature-controlled liquid and gas through the pinching body.

  In the production method of the present invention, it is preferable to sandwich a semi-fluid film having a solvent amount of 30% by mass to 1000% by mass with respect to the solid content in order to achieve the quenching position of the present invention. A more preferable residual solvent amount is 50% by mass to 600% by mass, and more preferably 70% by mass to 500% by mass with respect to the solid content.

  Moreover, in the manufacturing method of this invention, it is preferable from the viewpoint of making the viscosity of the semifluid film at the time of pinching the range of this invention perform volatilization of the solvent in the semifluid film from die exit to before pinching. Depending on the time of the clamping step, the solvent in the film after peeling off from the support or from the support may be volatilized. The amount of the solvent is preferably 30% by mass to 1000% by mass with respect to the solid content, more preferably 50% by mass to 600% by mass, and still more preferably 70% by mass to 500% by mass.

(Line speed)
In the production method of the present invention, the line speed is preferably 10 m / min to 300 m / min, more preferably 20 m / min to 250 m / min, and still more preferably in order to impart sufficient deformation to the semi-fluid film between the pinching bodies. 30 m / min to 200 m / min. By not falling below this range, sufficient molecular orientation can be provided, and by not exceeding this range, surface roughness due to friction between the semi-fluid film and the sandwiched body (shark skin) and molecular orientation derived from this can occur. Unevenness can be suppressed.

  In the manufacturing method of the present invention, the cylinder set value for pressing the clamping body is appropriately changed in order to clamp the pressure within the above range. The cylinder set value varies depending on the dope used and the material of the two pinching bodies. For example, when the effective width of the cast dope is 200 mm, it is preferably 3 to 100 KN, and preferably 3 to 50 KN. Is more preferable, and 3 to 25 KN is particularly preferable.

(Specific configuration of the clamping device)
As a method of continuously clamping the melt between the first clamping surface and the second clamping surface constituting the clamping device, the melt may be clamped between the belt and the belt, or between the belt and the roll. The roll may be sandwiched between rolls, but more preferably between rolls. By using the roll-to-roll method, it is possible to give abrupt deformation in a shorter time, and it is easier to form a multi-quenching structure. This is preferable because nonuniformity (unevenness) of the coordinate structure can be suppressed. More specifically, it is preferable to pass between two rolls (for example, a touch roll (first roll) and a chill roll (second roll) or a pair of nip rolls composed of two rolls).
In addition, in this specification, when it has multiple casting rolls which convey the said melt, the casting roll nearest to the most upstream supply means (for example, die | dye) is also called a chill roll. Hereinafter, the preferable aspect of the manufacturing method of this invention using two rolls is demonstrated.

  When these pinching bodies move at a peripheral speed, the peripheral speed difference is preferably 0% to 20%, more preferably 0.5% to 20%, and still more preferably 1% to 10%.

In the production method of the present invention, it is preferable to use a roll or belt having a shore hardness of 45 HS or more in order to achieve a clamping pressure in the above range. A preferable Shore hardness is 50 HS or more, and more preferably 60 to 90 HS.
The shore hardness can be obtained from the average value of values measured at 5 points in the width direction of the roll and belt and at 5 points in the circumferential direction using the method of JIS Z 2246.

The material of the roll and belt is preferably a metal from the viewpoint of achieving the Shore hardness, more preferably stainless steel, and a roll whose surface is plated is also preferred. Moreover, if the material of a roll and a belt is a metal, since the unevenness | corrugation of the surface is small and the surface of a film is hard to be damaged, it is preferable. Moreover, when the material of a roll and a belt is metal and is rigid, the pressure between a roll and a belt can be made high easily, and it is preferable. On the other hand, a metal roll or metal belt lined with a rubber roll or rubber can be used without particular limitation, but it is preferable that the roll pressure can be achieved.
With respect to the touch roll, for example, JP-A-11-314263, JP-A-2002-36332, JP-A-11-235747, WO97 / 28950, JP-A-2004-216717, JP The thing of 2003-145609 gazette can be utilized.

  In the manufacturing method of the present invention, it is preferable to use a metal touch roll having an outer cylinder thickness of 6 to 45 mm for at least one of the two rolls constituting the clamping apparatus. The outer cylinder thickness of the roll is preferably 6 mm to 45 mm, more preferably 10 mm to 40 mm, and still more preferably 15 mm to 35 mm. Such a roll is preferably a touch roll. If the metal outer cylinder thickness is 6 to 45 mm, more preferable regions of Re [0 °], Rth, and γ of the present invention can be achieved. Conventionally, a metal touch roll is as thin as 2 to 5 mm as in JP-A-11-235747, or a thickness of 50 mm or more as in a calendar roll.

  In the production method of the present invention, when a roll is used for the pinching body, it is preferable that at least one roll uses two rolls having a diameter of 300 to 2000 nm, more preferably 350 to 1500 nm. When a roll having a large diameter is used in this way, the contact time between the film-like dope and the roll becomes longer, and the time required for shearing becomes longer, so that it is easy to form an alignment structure, and the temperature of the dope is increased on the support. It is easy to be uniform and can be manufactured while suppressing variations in Re [0 °] and γ. In addition, in the manufacturing method of this invention, when using two rolls for a pinching body, both diameters may be equal or different.

By using a metal roll in this way, deformation due to the swelling of the roll by the solvent in the semi-fluid film can be suppressed, and the effect of pinching can be made uniform, and the nonuniformity (unevenness) of the quenching structure can be suppressed. This is preferable.
If the thickness of the metal outer cylinder does not fall below this range, deflection due to insufficient roll strength due to pinching will occur, which will cause cyclic deformation of the pinching portion, resulting in disturbance of the flow of the semi-fluid film. And the elimination of the multi-quenching structure formed thereby can be suppressed.
Further, since the thickness of the metal outer cylinder does not exceed the above range, it is possible to suppress the occurrence of delamination due to the surface orientation proceeding excessively by pressing the semi-fluid film of the pinching portion too much (as described above) However, if the roll strength (wall thickness) is too strong, the effect of absorbing the press pressure due to the deformation of the roll will be lost, and the half fluid The film is pushed too strongly, and the effect of plane orientation is superior to the effect of multi-quenching formation by the flow rate up, and the peel strength is reduced). It also has the effect of suppressing uneven pinching (normally, the temperature is adjusted by flowing a heat medium inside the roll, but if the roll is too thick, heat transfer cannot be performed sufficiently, and the dope temperature cannot be controlled and unevenness occurs. Easy to do).

  As a method for eliminating variations in Re [0 °] and γ, there is a method for increasing the adhesion when the dope contacts the pinching body. Specifically, the adhesion can be improved by combining electrostatic application method, air knife method, air chamber method, vacuum nozzle method and the like. Such an adhesion improving method may be performed on the entire surface of the dope or may be performed on a part thereof.

(Air gap)
The dope extruded from the die passes through the air gap (distance from the supply means outlet to the support) and is cast on the support, but the air gap is preferably preferably 3 to 1000 mm, More preferably, it is 5-800 mm, Most preferably, it is 10-500 mm. You may install a clamping device in the meantime.

(Support)
In the production method of the present invention, the support on which the dope is cast is preferably a drum or a band, and more preferably a drum. It is preferable that these drums and bands can be heated and cooled from the inside or the outside to adjust the temperature, whereby the amount of the solvent can be adjusted to a desired range and supplied to the pressure member.

  In the production method of the present invention, the support can be carried out at -40 ° C to 40 ° C, preferably -40 ° C to 15 ° C, more preferably -30 ° C to 10 ° C, and further preferably -25 ° C to 8 ° C. It is preferable to cool. Thereby, the elasticity of the dope can be increased, and a structure in which the extinction position due to the flow velocity is different depending on the distance from one end of the film in the thickness direction can be easily formed. Furthermore, it has the effect of making it difficult to eliminate the formed structure, and is effective when sandwiched between the die and the support.

For cooling such a support, it is preferable to use a drum rather than a band because the cooling efficiency is high and equipment can be simplified. Such an effect (increase in elastic modulus) is remarkable in the cellulose acylate resin, and is particularly remarkable when combined with dichloromethane as a solvent.
By not falling below the above range, the flow of the semi-fluid film is prevented from excessively decreasing, and the formation of a structure in which the extinction position varies depending on the distance in the thickness direction from one end of the film is promoted. On the other hand, by not exceeding the above range, it is possible to suppress the elimination of the structure in which the extinction position due to excessive fluidity varies depending on the distance in the thickness direction from one end of the film.

(Solidification of semi-fluid film)
The method for producing a film of the present invention includes a step of volatilizing and solidifying the solvent in the semifluid film after the step of clamping the semifluid film, and a step of solidifying by immersing the semifluid film in a poor solvent Among these, it is preferable to include at least one step from the viewpoint of fixing a structure in which the formed extinction position is different depending on the distance from one end of the film in the thickness direction.

  Thus, after the pinching step, a structure in which the extinction position varies depending on the distance in the thickness direction from one end of the film is fixed to the pinching body. For fixing, the solvent in the semifluid film may be volatilized, or it may be immersed in a poor solvent and solidified.

It is preferable that the solvent is volatilized by passing through a drying zone after clamping. Thus, by providing a drying zone after fluid deformation, it is preferable to fix the structure in which the extinction position formed by fluid deformation differs depending on the distance from one end of the film in the thickness direction by volatilizing the solvent. . In addition, after applying pressure to the dope, it is rapidly cooled to lower the mobility of the dope and fix the temporary structure. Different structures may be fixed.
The drying zone is preferably 100 ° C to 300 ° C, more preferably 110 ° C to 250 ° C, still more preferably 120 ° C to 200 ° C. The passage time is 10 minutes to 300 minutes, more preferably 15 minutes to 200 minutes, and still more preferably 20 minutes to 120 minutes. The film transport tension during this period is preferably 1 kg / m to 50 kg / m, more preferably 3 kg / m to 40 kg / m, and still more preferably 5 kg / m to 30 kg / m. Such drying may be performed in one stage or in multiple stages.

The manufacturing method of this invention includes the process of controlling the amount of residual solvents to 0.01-3 mass%. The method for controlling the amount of residual solvent so as to be within the scope of the present invention is not particularly limited, and an appropriate amount of solvent may be applied during film formation, and the solvent may be applied or immersed in the solvent after film formation. It can also be achieved by doing so. In the production method of the present invention, among them, a method of applying an appropriate amount of solvent from the film formation is preferable. This is because unevenness and wrinkles can be reduced more efficiently because the above-mentioned relaxation effect can be expressed immediately after the residual stress and the like are expressed due to pinching and stretching.
In the method of applying an appropriate amount of solvent from the film formation, the amount of residual solvent in the film of the present invention can be controlled by the drying time and drying temperature as described above.

  It is also preferable to solidify by exchanging the solvent in the semi-fluid film with a poor solvent. The poor solvent refers to a solvent having a resin solubility of 10% or less, and examples thereof include water, lower alcohols such as methanol, ethanol, and propanol, and mixtures thereof. Thus, after being immersed in a poor solvent, it dries on the said conditions. The temperature of the poor solvent is preferably −20 ° C. to 100 ° C., more preferably 0 ° C. to 70 ° C. The immersion time is preferably 1 second to 30 minutes, more preferably 10 seconds to 10 minutes.

  Further, it is preferable to trim both ends of the formed film. The portion cut off by trimming may be crushed and used again as a raw material. Further, it is also preferable to perform a thickness increasing process (knurling process) on one or both ends. The height of the unevenness due to the thickness increasing process is preferably 1 μm to 50 μm, more preferably 3 μm to 20 μm. Thickening processing may be convex on both sides or convex on one side. The width of the thickness increasing process is preferably 1 mm to 50 mm, more preferably 3 mm to 30 mm. Extrusion can be performed at room temperature to 300 ° C.

  Prior to winding, a laminated film may be attached to one side or both sides. The thickness of the laminated film is preferably 5 μm to 100 μm, more preferably 10 μm to 50 μm. The material is not particularly limited, such as polyethylene, polyester, and polypropylene.

  The winding tension is preferably 2 kg / m width to 50 kg / width, more preferably 5 kg / m width to 30 kg / width.

  In the manufacturing method of this invention, it is preferable that the film after film forming is 10 micrometers-200 micrometers, More preferably, they are 25 micrometers-150 micrometers, More preferably, they are 30 micrometers-90 micrometers. By making it above the lower limit of the above range, sufficient flow orientation can be provided between the compacting bodies, and by not exceeding the above range, the orientation distribution in the thickness direction is disturbed and the nonuniformity of Re [0 °] is suppressed. it can.

(Film width)
The width of the solution-formed or melt-formed film is preferably 1 m to 4 m, more preferably 1.2 m to 3.5 m, and still more preferably 1.4 m to 3 m.

<Stretching process in the direction parallel to the film surface>
In the film manufacturing method of the present invention, a stretching process in the direction parallel to the conventional film surface can be performed. The stretching treatment can be performed for the purpose of improving the film flatness, increasing the film strength, and adjusting the retardation value.

  As the stretching direction, the longitudinal direction (MD) and the width direction (TD) are generally used, but the stretching direction may be oblique with respect to the longitudinal direction.

  Initially, the extending | stretching method of a longitudinal direction (MD) is demonstrated.

  One-stage or multi-stage MD stretching may be performed in the longitudinal direction. When stretching, assuming that the glass transition temperature of the film is Tg, the film is heated within the range of (Tg-30) to (Tg + 100) ° C., more preferably (Tg-20) to (Tg + 80) ° C. MD) or transverse direction (TD) is preferred. It is preferable to perform transverse stretching within the temperature range of (Tg-20) to (Tg + 20) ° C. and then heat-set. It is also preferable to perform relaxation treatment after the stretching step. In addition, Tg at the time of describing about extending | stretching points out Tg in the state of the film at the time of extending | stretching, for example, when extending | stretching in the state containing a solvent, it points out Tg in the state. Such Tg can be determined by enclosing a film containing a solvent in a hermetic pan in the same manner as in stretching and performing DSC measurement.

  Tg in the state which does not contain the solvent of an optical film has preferable 110 degreeC or more, and also 120 degreeC or more is preferable. This is because when the optical film according to the present invention is used in a liquid crystal display device, if the Tg of the film is lower than the above, molecules fixed inside the film due to the influence of the temperature and humidity of the use environment and the heat of the backlight. The orientation state of the film is affected, and there is a high possibility that the retardation value and the dimensional stability and shape of the film will greatly change. In addition, the shape of the film may not be maintained. Conversely, if the Tg of the film is too high, it becomes difficult to produce because it approaches the decomposition temperature of the film constituting material, and the presence of a volatile component or coloring may occur due to the decomposition of the material itself used when forming a film. Accordingly, the glass transition temperature is preferably 180 ° C. or lower, more preferably 150 ° C. or lower. At this time, the Tg of the film can be determined by the method described in JIS K7121.

  In the longitudinal stretching step, at least two pairs of nip rolls are used, and a first nip roll composed of two rolls installed on the upstream side in the film transport direction while heating between the two nip rolls, and two rolls installed on the downstream side The peripheral speed of the second nip roll can be made higher than the peripheral speed of the first nip roll on the upstream side.

In the longitudinal stretching step, it is preferable that the glass transition temperature of the resin is Tg-20 ° C to Tg + 50 ° C, more preferably Tg-10 ° C to Tg + 40 ° C, and further preferably Tg-5 ° C to Tg + 30 ° C. In addition, the longitudinal stretching ratio in the longitudinal stretching step is preferably 1.05 to 3 times, more preferably 1.1 to 2.5 times, and still more preferably 1.2 to 2.2 times. It is.
The diameter of a preferable nip roll is preferably 30 mm to 1500 mm, more preferably 80 mm to 1000 mm, and still more preferably 150 mm to 700 mm. Further, the two rolls constituting the nip roll are preferable from the viewpoint of uniforming the film from which the diameters are equal.

  A preferable nip pressure is preferably 10 kg / cm to 100 kg / cm, more preferably 20 kg / cm to 80 kg / cm, and still more preferably 25 kg / cm to 70 kg / cm.

The preferred longitudinal stretching speed (the nip roll inlet side (before stretching) speed is preferably 5 m / min to 100 m / min, more preferably 10 m / min to 80 m / min, still more preferably 15 m / min to 60 m / min. is there.
In such a longitudinal stretching step, for example, Japanese Patent Application Laid-Open No. 2007-301978, Japanese Patent Application Laid-Open No. 2004-133323, Japanese Patent Application Laid-Open No. 2005-264022, Japanese Patent Application Laid-Open No. 2005-330412, Japanese Patent Application Laid-Open No. 2006-130484, and Japanese Patent Application Laid-Open No. 2007-121352. JP-A-2008-39808, JP-A-2008-93946, JP-A-2008-185726, etc. can be used.

  Next, the extending | stretching method of a lateral direction (TD) is demonstrated.

  In the case of TD stretching, it is preferable to perform transverse stretching while sequentially raising the temperature difference in the range of 1 to 50 ° C. in a stretching region divided into two or more, because the distribution of physical properties in the width direction can be reduced. Further, after transverse stretching, it is preferable that the film is held at a temperature not higher than the final TD stretching temperature and not lower than Tg−40 ° C. for 0.01 to 5 minutes because the distribution of physical properties in the width direction can be further reduced.

The transverse stretching can be performed using a tenter. That is, the film is stretched by holding both ends in the width direction with clips and widening the film in the lateral direction. At this time, the stretching temperature can be controlled by sending wind at a desired temperature into the tenter. The temperature of the blowing air is preferably 30 ° C to 150 ° C, more preferably 45 ° C to 135 ° C, and still more preferably 50 ° C to 120 ° C. Further, the preferred transverse draw ratio exceeds 1.00 times and is 2.50 times, more preferably 1.10 to 2.20 times, and still more preferably 1.20 to 1.80 times.
It is preferable to shrink in the longitudinal direction simultaneously with the transverse stretching or after the transverse stretching. A preferable magnification is 0.40 times or more and less than 1.00 times, more preferably 0.50 times or more and 0.95 times or less, and further preferably 0.60 times or more and 0.90 times or less. Here, the magnification is obtained by dividing the length before the shrinking process by the length after the shrinking process. Such contraction in the vertical direction can be performed by the following method.
The longitudinal shrinkage may be performed during the transverse stretching or after the transverse stretching. The longitudinal shrinkage can be specifically carried out in the following <1> to <4>, but <2> and <4> are more preferable. These may be carried out alone or in combination.
(1) Longitudinal contraction after transverse stretching <1> The feeding speed of the clip in the tenter feeding following the transverse stretching (tenter stretching) is made slower than the feeding speed of the clip being stretched.
Such longitudinal shrinkage can be achieved, for example, by preparing separate tenter rails for lateral stretching and longitudinal shrinkage so that the speed can be controlled independently. For example, those described in JP-A-6-210726, JP-A-6-278204, JP-A-11-77825, JP-A-2004-195712, JP-A-2006-142595, etc. are used. It can be realized by contracting vertically (conveying direction).

<2> After transverse stretching by the tenter (after removing the clip of the tenter), the stretched film is put in the heat treatment zone, and heat treated while the transport speed of the stretched film is slower from the inlet side to the outlet side. Further, in order to preferentially generate the shrinkage in the vertical direction, the aspect ratio of the heat treatment zone (a value obtained by dividing the zone length by the inlet side film width) is preferably 0.01 to 2, more preferably 0.05. It is -1.6, More preferably, it is 0.1-1.3.
Such longitudinal shrinkage can be achieved, for example, by providing a nip roll at the exit of the heat treatment zone provided after the tenter and delaying this speed as described above from the transport speed of the tenter. Further, it can be achieved by preparing two or more pairs of nip rolls and delaying the conveying speed on the outlet side as described above from the inlet side. Such heat treatment may be performed by providing a heat treatment zone or a heater between the nip rolls, or may be performed by heating the nip roll and adjusting the resin film to the above range. This longitudinal shrinkage may be carried out continuously after the transverse stretching, or may be carried out by feeding out the material once wound after the transverse stretching.
It is necessary to suppress contraction in the horizontal direction and perform contraction only in the vertical direction. For this purpose, it is effective that the shrinkage in the width direction can be suppressed by the frictional force between the roll and the resin film by passing between a large number of rolls. The roll wrap length (W) / inter-roll length (G) is preferably 0.01 or more and 3 or less, more preferably 0.03 or more and 1 or less, and still more preferably 0.05 or more and 0.5 or less. The number of rolls is preferably 2 or more and 100 or less, more preferably 3 or more and 50 or less, and still more preferably 4 or more and 20 or less. The diameter of the preferable roll is preferably 5 cm to 100 cm, more preferably 10 cm to 80 cm, and still more preferably 15 cm to 60 cm.

<3> It is achieved by shrinking the resin film in the transport direction on the tenter chuck. That is, the resin film can be longitudinally shrunk by slipping in the transport direction on the chuck during or after transverse stretching. Although the stretched resin film tends to shrink and contraction stress acts, it is gripped by a chuck in the stretch (width) direction and cannot shrink. On the other hand, if the resin film is slid in the conveyance (longitudinal) direction on the chuck, it can be contracted longitudinally by this contraction stress. Such a method is not particularly limited, but can be achieved, for example, by installing a pulley in the conveying direction in the clip portion of the chuck, or by attaching a slipping material (eg, Teflon) to the resin film gripping surface of the clip. Good.

(2) Longitudinal shrinkage during transverse stretching <4> Longitudinal shrinkage during transverse stretching is achieved by stretching in the width direction while slowing the conveying speed of the clips in the tenter from the inlet side toward the outlet side during transverse stretching. For example, it can be performed using a biaxial stretching machine, and specifically, transverse stretching and longitudinal shrinkage can be performed automatically. For example, Japanese Patent Application Laid-Open No. 2003-111533, Japanese Patent Application Laid-Open No. Hei 6-210726, Japanese Patent Application Laid-Open No. Hei 6-278204, Japanese Patent Application Laid-Open No. Hei 11-77825, Japanese Patent Application Laid-Open No. 2000-24695, Japanese Patent Application Laid-Open No. 2004-195712, Japanese Patent Application Laid-Open No. 2006-142595, Japanese Patent Application Laid-Open No. 2006-142595, Devices described in JP-A-2006-22916, JP-A-2008-44339, and the like can be used. Specifically, a high-performance thin film device (trade name FITZ) manufactured by Ichikin Kogyo Co., Ltd. can be used. This device can arbitrarily set the stretching ratio in the longitudinal direction (longitudinal direction of the film = traveling direction of the film) and the stretching ratio in the lateral direction (width direction = vertical direction with respect to the traveling direction of the film). ) Can be arbitrarily set, so that stretching and shrinking can be simultaneously performed under predetermined conditions. Also, for example, by appropriately combining a rail width control method, a panda graph method, a method for controlling the traveling speed by a linear motor, etc., which are generally known, the stretching ratio in the width direction is controlled, and the film edge portion It is also possible to use a biaxial stretching machine or the like that controls the length in the longitudinal direction by changing the interval between the clips that sandwich the clip.

By performing preheating before stretching and heat setting after stretching, the Re and Rth distribution after stretching can be reduced, and the variation in orientation angle associated with bowing can be reduced. Either preheating or heat setting may be performed, but both are more preferable. These preheating and heat setting are preferably performed by holding with a clip, that is, preferably performed continuously with stretching.
The preheating can be performed at a temperature about 1 ° C to 50 ° C higher than the stretching temperature, preferably 2 ° C to 40 ° C or less, more preferably 3 ° C to 30 ° C. The preheating time is preferably 1 second to 10 minutes, more preferably 5 seconds to 4 minutes, and even more preferably 10 seconds to 2 minutes. During preheating, it is preferable to keep the width of the tenter substantially constant. Here, “substantially” refers to ± 10% of the width of the unstretched film.

The heat setting is performed at a temperature higher than the final TD stretching temperature and usually within 0.5 to 300 seconds within a temperature range of Tg-20 ° C. or less. Under the present circumstances, it is preferable to heat-fix, heating up sequentially in the range from which a temperature difference is set to 1-100 degreeC in the area | region divided into 2 or more.
At the time of heat setting, 0% of the tenter width after completion of stretching (the same width as the tenter width after stretching) to -10% (shrinking by 10% from the tenter width after stretching = contraction width) It is preferable that the effect of shrinking in the direction is more easily expressed. If the width is wider than the stretched width, residual strain tends to occur in the film, which is not preferable.

  The heat-set film is usually cooled to Tg or less, and clip holding portions at both ends of the film are cut and wound. At this time, it is preferable to perform a relaxation treatment of 0.1 to 10% in the lateral direction and / or the longitudinal direction within a temperature range of not more than the final heat setting temperature and not less than Tg. In addition, it is preferable that the cooling is gradually performed from the final heat setting temperature to Tg at a cooling rate of 100 ° C. or less per second. Means for cooling and relaxation treatment are not particularly limited, and can be performed by a conventionally known means. In particular, it is preferable to carry out these treatments while sequentially cooling in a plurality of temperature ranges from the viewpoint of improving the dimensional stability of the film. The cooling rate is a value obtained by (T1-Tg) / t, where T1 is the final heat setting temperature and t is the time until the film reaches Tg from the final heat setting temperature.

  The more optimal conditions of these heat setting conditions, cooling, and relaxation treatment conditions vary depending on the types of additives such as resins and plasticizers such as polycarbonate and cellulose ester constituting the film. What is necessary is just to determine by measuring and adjusting suitably so that it may have a preferable characteristic.

(Relaxation treatment)
Furthermore, dimensional stability can be improved by performing relaxation treatment after these longitudinal and transverse stretching. Thermal relaxation is preferably performed either after film formation, after longitudinal stretching, or after lateral stretching, or both. The relaxation treatment may be performed online continuously after stretching, or may be performed offline after winding after stretching.
Thermal relaxation is (Tg-30) ° C to (Tg + 30) ° C, more preferably (Tg-30) ° C to (Tg + 20) ° C, and more preferably (Tg-15) ° C to (Tg + 10) ° C for 1 second to 10 minutes. More preferably 5 seconds to 4 minutes, still more preferably 10 seconds to 2 minutes, 0.1 kg / m to 20 kg / m, more preferably 1 kg / m to 16 kg / m, still more preferably 2 kg / m to 12 kg / m. It is preferable to carry out while conveying with tension.

<Method for producing second aspect (stretched and contracted film orthogonal to stretch direction)>
Next, the manufacturing method of the film of the 2nd aspect of this invention is demonstrated. The film production method of the second aspect of the present invention is characterized by comprising a step of stretching the semifluid film at a stretch ratio of X times and a step of shrinking Y times in the direction orthogonal to the stretch direction.
1.00 <X <2.50
0.40 <Y <1.00
The preferred ranges of X and Y are the same as the preferred ranges of transverse stretching and longitudinal shrinkage in the film production method of the first aspect of the present invention described above.

Patent Document 1 discloses a technique in which a film after film formation is used as an optical compensation film for a liquid crystal display substrate by applying shear between a pair of rolls having a difference in peripheral speed to incline the optical axis.
In JP 2010-61091 A, a film-forming film is stretched X times (1.00 <X <2.5) in the direction orthogonal to the transport direction, and Y times (0.40 <Y <1.00) in the transport direction. ) After stretching, a technique for forming an inclined axis by applying shearing between a pair of rolls having a specific roll interval and a peripheral speed difference is disclosed. As a result, the problem (scratch on the surface) of Patent Document 1 is solved.
However, in Patent Document 1 and Japanese Patent Application Laid-Open No. 2010-61091, wrinkles are generated in a heat treatment such as a drying step (50 to 150 ° C.) in forming a polarizing plate, and a solution has been desired.
On the other hand, in the method for producing a film of the second aspect of the present invention, an optical film that hardly causes wrinkles due to heat treatment or the like can be provided by adopting the above configuration.

(Lateral stretching + longitudinal shrinkage)
In the film manufacturing method of the second aspect of the present invention, the stretching is preferably stretching in a direction perpendicular to the transport direction.
By producing the stretch in a direction perpendicular to the transport direction, that is, by combining “lateral stretching + longitudinal shrinkage”, generation of wrinkles during heat treatment can be further reduced, and optical unevenness can be further reduced.
Although not bound by any theory, the influence on the extinction angle can be reduced by stretching in the direction perpendicular to the extinction angle (width direction). In addition, such molecular orientation accompanied by a change in the extinction angle appears in the vertical direction (film forming direction). By adding a stretching in the transverse direction to this, the molecules are also oriented in the transverse (width) direction. As a result, the vertical alignment and the horizontal alignment cancel each other, and the generation of wrinkles that are increased by the vertical and horizontal anisotropy of heat shrinkage can be suppressed. Further, when the film is contracted in the vertical direction during the lateral extension, the horizontal orientation of the molecules is further promoted and the effect is increased.

  In such transverse stretching, by combining longitudinal shrinkage, the molecular orientation in the transverse direction can be further promoted, the above-described effects become obvious, and the optical characteristics (uniformity) are greatly improved.

  Such stretching may be performed either before or after clamping, but is preferably performed before clamping. That is, in the film manufacturing method according to the second aspect of the present invention, it is preferable to carry out the stretching step before the clamping. Before the pinching, the entire film is oriented in the width direction (this is uniformly oriented in the thickness direction), and by pinching this, a distribution of extinction angles is formed. As a result, a portion having a small extinction angle is also oriented, and optical unevenness caused by a small orientation is reduced. On the other hand, even if stretched after pinching, molecules with a small extinction angle are oriented, and the optical unevenness caused by the small orientation is reduced, but stretches in the direction perpendicular to the extinction angle direction. The extinction angle formed in this is easily reduced.

(Pinch area)
In the method for producing a film of the second aspect of the present invention, it is preferably performed between the outlet of the supply means (for example, die) and the drying zone, and more preferably, the film is peeled off from the support in a state containing the solvent. Between the drying zone. Accordingly, in the present invention, (1 ′) a clamping body may be provided at the die outlet (die lip portion), (2 ′) a clamping surface may be installed between the die and the support, (3 ') A clamping surface may be installed on the band or drum support (in this case, one clamping surface will be a band or drum), and (4') is peeled off from the support and sandwiched by the clamping surface during transport. But you can. The method (4 ′) is more preferable.
Fixing the "structure where the extinction position varies depending on the distance in the thickness direction from one end of the film" formed by fluid deformation by volatilizing the solvent by providing a drying zone after fluid deformation in this way Is preferred. In addition, after applying pressure to the dope, it is rapidly cooled to lower the mobility of the dope and fix the temporary structure. Then, it is brought into the drying zone and rapidly dried. Depending on the structure, it may be fixed.

(Clamping device)
In the film manufacturing method according to the second aspect of the present invention, examples of the pressing device having different speeds on the first pressing surface and the second pressing surface include a combination of two rolls, and Japanese Patent Application Laid-Open No. 2000-219752. And a combination of a roll and a touch belt (single-sided belt method), a combination of a belt and a belt (double-sided belt method), and the like. Among these, two rolls are preferable because the pressure can be applied uniformly.

  In the film manufacturing method of the second aspect of the present invention, it is preferable to apply a pressure of 20 MPa to 500 MPa between the clamping devices, more preferably 30 to 300 MPa, and further preferably 40 to 200 MPa.

  In the film production method of the second aspect of the present invention, the difference in moving speed of the clamping surface of the clamping device is preferably 0% or more and 20% or less, more preferably 0.5% or more and 20% or less, and still more preferably. 1% or more and 10% or less.

[Polarizer]
<Polarizing plate using the film of the first aspect (not stretched and contracted perpendicular to the stretching direction)>
The polarizing plate of the first aspect of the present invention can be obtained by laminating at least a polarizer (hereinafter also referred to as a polarizing film) on the film of the first aspect of the present invention. Hereinafter, the polarizing plate of the first embodiment of the present invention will be described. Examples of the polarizing plate of the present invention include a polarizing plate formed on the surface of a polarizing film for the purpose of two functions of a protective film and viewing angle compensation, and a composite polarizing plate laminated on a protective film such as TAC. Can be mentioned.

  If the polarizing plate of this invention uses the film and polarizer of this invention, there will be no restriction | limiting in particular in a structure. For example, when the polarizing plate of the present invention is composed of a polarizer and two polarizing plate protective films (transparent polymer films) that protect both sides of the polarizer, the film of the present invention may be used as at least one polarizing plate protective film. it can. Moreover, the polarizing plate of this invention may have an adhesive layer for sticking with another member in the at least one surface. Moreover, in the polarizing plate of this invention, if the surface of the film of this invention is an uneven | corrugated structure, it will have an anti-glare (anti-glare) function. Further, the polarizing plate of the present invention has an antireflection film of the present invention in which an antireflection layer (low refractive index layer) is further laminated on the surface of the film of the present invention, and further optical anisotropy on the surface of the film of the present invention. It is also preferable to use the optical compensation film of the present invention in which layers are laminated.

  In general, a liquid crystal display device includes four polarizing plate protective films because a liquid crystal cell is provided between two polarizing plates. The film of the present invention may be used for any of the four polarizing plate protective films, but the film of the present invention is particularly advantageous as a protective film disposed between a liquid crystal cell and a polarizing plate in a liquid crystal display device. Can be used.

  The polarizing plate of the present invention more preferably has a configuration in which a cellulose acylate film, a polarizer and a film of the present invention are laminated in this order. Moreover, the structure which the cellulose acylate film, the polarizer, the film of this invention, and the adhesive layer are laminated | stacked in this order is also more preferable.

(Optical film)
The film of the present invention is used for the optical film of the polarizing plate of the present invention. In addition, the film can be surface-treated. Examples of the surface treatment method include methods such as corona discharge, glow discharge, UV irradiation, and flame treatment.

(Cellulose acylate film)
As the cellulose acylate film of the polarizing plate of the present invention, a known cellulose acylate film for a polarizing plate is used. For example, a known triacetyl cellulose (TAC) film (for example, Fujitac T-60 manufactured by Fuji Film Co., Ltd.) can be preferably used. The lurose acylate film may be surface treated. Examples of the surface treatment method include saponification treatment.

(Polarizer)
As the polarizer, for example, a film obtained by immersing and stretching a polyvinyl alcohol film in an iodine solution can be used.

  As the polarizer used in the present invention, any appropriate one can be selected as long as the object of the present invention can be achieved. Examples of the polarizer include a uniaxially stretched film obtained by adsorbing a dichroic substance such as iodine or a dichroic dye on a hydrophilic polymer film, a dehydrated polyvinyl alcohol product or a dehydrochlorinated polyvinyl chloride product. And polyene-based oriented films. Examples of the hydrophilic polymer film include a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, and an ethylene / vinyl acetate copolymer partially saponified film. In the present invention, a polarizer in which iodine is adsorbed on a polyvinyl alcohol film is preferable.

  The polarizer preferably further contains at least one of potassium and boron. When the polarizer contains potassium and boron, a polarizer (polarizing plate) having a composite elastic modulus (Er) in a preferable range and having a high degree of polarization can be obtained. For production of a polarizer containing at least one of potassium and boron, for example, a film which is a material for forming a polarizer may be immersed in a solution of at least one of potassium and boron. The solution may also serve as a solution containing iodine.

  Any appropriate molding method can be adopted as a method for obtaining the polyvinyl alcohol film. A conventionally known method can be applied as the molding method. Moreover, a commercially available film can be used as it is for the polyvinyl alcohol film. Examples of commercially available polyvinyl alcohol films include the product name “Kuraray Vinylon Film” manufactured by Kuraray Co., Ltd., the product name “Tosero Vinylon Film” manufactured by Tosero Co., Ltd., and the product manufactured by Nippon Synthetic Chemical Industry Co., Ltd. Names include “Nippon Vinylon Film”.

  Regarding an example of a method for producing a polarizer, for example, a polymer film (raw film) mainly composed of a polyvinyl alcohol resin is immersed in a swelling bath containing pure water and a dyeing bath containing an aqueous iodine solution. Swelling treatment and dyeing treatment are performed while applying tension in the film longitudinal direction with different rolls. Next, the film subjected to the swelling treatment and the dyeing treatment is immersed in a crosslinking bath containing potassium iodide, and is subjected to crosslinking treatment and final stretching treatment while tension is applied in the longitudinal direction of the film with rolls having different speed ratios. Is given. The film subjected to crosslinking treatment is immersed in a washing bath containing pure water by a roll and subjected to a washing treatment. The film subjected to the water washing treatment is dried and wound up after adjusting the moisture content. Thus, the polarizer can be obtained by stretching the original film, for example, 5 to 7 times the original length.

  The polarizer may be subjected to any surface modification treatment in order to improve the adhesion with the adhesive. Examples of the surface modification treatment include corona treatment, plasma treatment, glow discharge treatment, flame treatment, ozone treatment, UV ozone treatment, and ultraviolet treatment. These treatments may be used alone or in combination of two or more.

(Adhesive layer)
The polarizing plate of the present invention may have an adhesive layer as at least one of the outermost layers (such a polarizing plate may be referred to as an adhesive polarizing plate). As a particularly preferred embodiment, a pressure-sensitive adhesive layer for adhering to another member such as another optical film or a liquid crystal cell can be provided on the side of the optical film where the polarizer is not adhered.

(Production method of polarizing plate)
The manufacturing method of the polarizing plate of this invention is demonstrated.
The polarizing plate of the present invention can be produced by bonding one side of the film of the present invention (a surface-treated surface in the case of surface treatment) to at least one side of the polarizer using an adhesive. When the cellulose acylate film, the polarizer and the film of the present invention are bonded together in this order, the polarizing plate of the present invention can be produced by laminating the polarizer and other films using an adhesive on both sides of the polarizer. . In the manufacturing method of the polarizing plate of this invention, it is preferable that the film of this invention is directly bonded with the polarizer.

  As the adhesive, a known polarizing plate production adhesive can be used. Moreover, the aspect which has an adhesive bond layer between the said polarizer and each film is also preferable. Specific examples of the adhesive include an aqueous solution of polyvinyl alcohol or polyvinyl acetal (eg, polyvinyl butyral) and a latex of a vinyl-based polymer (eg, polybutyl acrylate). A particularly preferred adhesive is an aqueous solution of fully saponified polyvinyl alcohol. The polyvinyl alcohol-based adhesive preferably contains a polyvinyl alcohol-based resin and a crosslinking agent.

  The manufacturing method of the polarizing plate of this invention is not limited to said method, Another method can also be used. For example, JP 2000-171635, JP 2003-215563, JP 2004-70296, JP 2005-189437, JP 2006-199788, JP 2006-215463, JP 2006-227090. JP, 2006-243216, JP 2006-243681, JP 2006-259313, JP 2006-276574, JP 2006-316181, JP 2007-10756, JP 2007-128025, Use methods described in JP 2007-140092, JP 2007-171943, JP 2007-197703, JP 2007-316366, JP 2007-334307, JP 2008-20891, etc. it can. Among these, the methods described in JP-A-2007-316366 and JP-A-2008-20891 are more preferable.

  It is preferable that a protective film is also attached to the other surface of the polarizing film, and the protective film may be the film of the present invention. Moreover, the various films conventionally used as a protective film of a polarizing plate, such as a cellulose acylate film and a cyclic polyolefin polymer film, can be used.

  The polarizing plate of the present invention thus obtained is preferably used in a liquid crystal display device, and may be provided on either the viewing side or the backlight side of the liquid crystal cell, or on both sides. Not. Specific examples of the image display device to which the polarizing plate of the present invention can be applied include a self-luminous display device such as an electroluminescence (EL) display, a plasma display (PD), and a field emission display (FED: Field Emission Display). Can be mentioned. The liquid crystal display device is applied to a transmissive liquid crystal display device, a reflective liquid crystal display device, and the like.

<Polarizing plate using the film of the second embodiment (stretched and contracted perpendicular to the stretching direction)>
The film of the second aspect according to the present invention can be used as a film having both the function of an optical compensation film and the function of a polarizing plate protective film, and the method for producing the polarizing plate of the second aspect is not particularly limited. Can be produced by a typical method. The film according to the present invention is bonded to at least one surface of a polarizer produced by subjecting the obtained film to an alkali treatment and immersing and stretching the polyvinyl alcohol film in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. On the opposite side of the polarizer, as the following conventional polarizing plate protective film, Konica Minoltak KC8UX, KC4UX, KC5UX, KC8UY, KC4UY, KC8UCR-3, KC8UCR-4, KC12UR, KC8UXW-H, KC8UYW-HA, A cellulose ester film such as KC8UX-RHA (manufactured by Konica Minolta Opto Co., Ltd.) can be used.

  Further, instead of the alkali treatment, easy-adhesion processing as described in JP-A-6-94915 and JP-A-6-118232 may be applied to perform polarizing plate processing.

(Display device)
By using the film manufactured by the film manufacturing method of the second aspect of the present invention, various display devices having excellent visibility can be produced. The film according to the present invention is preferably a reflective, transmissive, transflective LCD, or TN, STN, OCB, HAN, VA (PVA, MVA), or IPS LCD. Used.

  In addition, the aromatic polycarbonate film is excellent in flatness and is preferably used in various display devices such as a plasma display, a field emission display, an organic EL display, an inorganic EL display, and electronic paper.

[Liquid Crystal Display]
<Liquid Crystal Display Device Using Film of First Aspect (Not Stretched and Shrinking perpendicular to Stretching Direction)>
The film and polarizing plate of the first embodiment of the present invention can be used in various modes of liquid crystal display devices. Preferably, it can be used for a TN (twisted nematic), OCB (optically compensatory bend), or ECB (electrically controlled birefringence) mode liquid crystal display device, and more preferably for a TN or ECB mode liquid crystal display.

<Liquid crystal display device using the film of the second embodiment (stretched and contracted perpendicular to the stretching direction)>
In a liquid crystal display device, a substrate containing liquid crystal is usually disposed between two polarizing plates. However, a polarizing plate protective film to which the optical film according to the present invention is applied has high flatness and retardation uniformity. Excellent display properties can be obtained even if it is placed on the site. A polarizing plate protective film provided with a clear hard coat layer, an antiglare layer, an antireflection layer, or the like is preferably used for this portion of the polarizing plate protective film on the outermost display side of the liquid crystal display device. In the case of a polarizing plate protective film provided with an optical compensation layer, or a polarizing plate protective film provided with an appropriate optical compensation capability by stretching operation or the like, it is excellent in being disposed at a site in contact with the liquid crystal cell. Displayability is obtained. In particular, the use of the present invention for a multi-domain type liquid crystal display device, more preferably a multi-domain type liquid crystal display device with a birefringence mode, can further exhibit the effects of the present invention.

Multi-domain is a method of dividing a liquid crystal cell that constitutes one pixel into a plurality of parts, and is suitable for improving the viewing angle dependency and the symmetry of image display. Various methods have been reported. “Okita, Yamauchi: Liquid Crystal, 6 (3), 303 (2002)”. The liquid crystal display cell is “Yamada, Yamahara: Liquid crystal, 7 (2), 18
(2003) ", but is not limited thereto.

  The display quality of the display cell is preferably symmetrical with respect to human observation. Therefore, when the display cell is a liquid crystal display cell, it is possible to multiplex domains by giving priority to the symmetry on the observation side. A known method can be used to divide the domain, and can be determined in consideration of the properties of a known liquid crystal mode by a two-part dividing method, more preferably a four-part dividing method.

  The polarizing plate includes an MVA (Multi-domain Vertical Alignment) mode typified by a vertical alignment mode, in particular, an MVA mode divided into four, a known PVA (Patterned Vertical Alignment) mode multi-domained by an electrode arrangement, an electrode arrangement, It can be effectively used in a CPA (Continuous Pinwheel Alignment) mode that fuses the chiral ability. In addition, a proposal of an optically biaxial film in the adaptation to the OCB (Optical Compensated Bend) mode has been disclosed, and “T. Miyashita, T. Uchida: J. SID, 3 (1), 29 ( 1995) ", the effect of the present invention can be exhibited in display quality by the polarizing plate. If the effect of the present invention can be exhibited by using a polarizing plate, the arrangement of the liquid crystal mode and the polarizing plate is not limited.

  Since the liquid crystal display device has high performance as a device for colorization and moving image display, the display quality of the liquid crystal display device using the optical film according to the present invention, particularly a large liquid crystal display device, is less fatigued and faithful. Image display is possible.

<< TN type liquid crystal display device >>
A TN liquid crystal display device in which the optical film according to the present invention is particularly preferably used will be described.

  The TN liquid crystal display device is not particularly limited. Further, the light source may further have a light source, and the light source is not particularly limited. However, for example, a planar light source that emits polarized light is preferable because light energy can be used effectively.

  An example of a TN type liquid crystal display device in which an optical film is particularly preferably used will be described with reference to FIGS. 3 and 4 of JP 2010-61091A. Hereinafter, in this specification, reference to FIGS. 3 and 4 means FIGS. 3 and 4 of Japanese Patent Application Laid-Open No. 2010-61091. Each of the first polarizing plate 13 and the second polarizing plate 15 has a structure in which the polarizing films 2 and 10 are sandwiched between two polarizing plate protective films (the polarizing film 2 includes the first polarizing plate protective film 1 and the second polarizing plate 2). (The polarizing film 10 is sandwiched between the third polarizing plate protective film 9 and the fourth polarizing plate protective film 11).

  Ro and Rt of the 2nd polarizing plate protective film 3 and the 3rd polarizing plate protective film 9 exist in the range of 15 <= Ro <= 70, 70 <= Rt <= 200.

  The TN liquid crystal cell 14 has a liquid crystal layer 6 in a space sandwiched between two glass cell substrates 4 and 8. The average thickness of the liquid crystal layer 6 is the liquid crystal cell gap.

  The glass cell substrates 4 and 8 are provided with alignment layers 5 and 7 for aligning liquid crystals, and the alignment layers are rubbed. The twist angle of the liquid crystal coincides with the direction of the opposing rubbing process, that is, the angle formed by the rubbing axis, and the angle formed by the rubbing axis of the alignment film 5 (reference 0 °) and the rubbing axis of the alignment film 7 is 115 ± 22. °.

  The angle formed by the transmission axis of the first polarizing plate 13 (equal to the transmission axis of the polarizing film 2) and the rubbing axis of the liquid crystal alignment layer 5 is 3.5 ± 3 °, and the transmission axis of the second polarizing plate 15 The angle formed by (the same as the transmission axis of the polarizing film 10) and the rubbing axis of the liquid crystal alignment layer 7 is 3.5 ± 3 °.

  Note that the first polarizing plate and the second polarizing plate are arranged so as to be crossed Nicols (the transmission axes of each other form 90 °).

  The optical film of the present invention is preferably used as the second polarizing plate protective film 3 and the third polarizing plate protective film 9 having an optical compensation function and a polarizing plate protective function.

  Although not shown, a cellulose ester film having a polarizing plate protective function is used for the second polarizing plate protective film 3 and the third polarizing plate protective film 9, and the optical film of the present invention is used as an optical compensation film. The correspondence which installs in two places (both sides of a liquid crystal cell) between the 2nd polarizing plate protective film 3 and the glass cell substrate 4 and between the 2 polarizing plate protective film 9 and the glass cell substrate 8 is also a preferable correspondence.

[Optical compensation film]
The film of the present invention can be preferably used as a film for optical applications, and can be particularly preferably used as an optical compensation film.

<Laminated film>
If necessary, the film of the present invention can further be provided with an optically anisotropic layer.

  The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. Unless otherwise specified, “part” in the examples represents “part by mass”.

<Measurement method>
(1) Residual amount of film, amount of solvent in semi-fluid film 300 mg of sample film is a solvent (not particularly limited as long as it dissolves the film, but in this example, TAC, CAP-1 to CAP-3, DAC, Dissolve in 30 ml) using dichloromethane for acrylic and PC, and n-hexane for COP and COC. This film solution is measured under the following conditions using gas chromatography (GC).

Column: DB-WAX (0.25 mmφ × 30 m, film thickness 0.25 μm)
Column temperature: 50 ° C
Carrier gas: Nitrogen analysis time: 15 minutes Sample injection volume: 1 μl
Obtain the amount of solvent from the calibration curve measured in advance, and divide by the amount of sample to obtain the amount of residual solvent.

(2) Extinction Position According to the method described in the specification, the extinction position of the film of Example 1 was observed with a polarizing microscope (Eclipse E600POL manufactured by NIKON) while being rotated by 1 °. From the obtained results, the first observed extinction position and the last observed extinction position were measured and listed in Tables 1 and 2.

(3) Re [0 °], γ, Rth, CRe [40 °]
These optical properties were measured according to the method described in the specification.

(4) Nipping pressure Nipping pressure is obtained by sandwiching a prescale for medium pressure (manufactured by FUJIFILM Corporation) between two rolls controlled at 25 ° C at a constant circumferential speed (5 m / min) without a semi-fluid film. And the value was defined as the pressure (clamping pressure) at the time of clamping.

(5) Viscosity of semi-fluid film A semi-fluid film at a pinched portion is sampled, and this is measured at the temperature of the pinched body at the time of pinching using a cone plate type rheometer (for example, Physica MCR301 manufactured by Anton Paar). Measure at a shear rate of 1 sec-1. The cone plate was sealed to prevent the solvent from evaporating during the measurement.

(resin)
(1) COC (addition polymerization type norbornene resin)
TOPAS6013 (Tg = 130 ° C) manufactured by Polyplastics Co., Ltd.
(2) COP (ring-opening polymerization type norbornene resin)
Compound of Example 1 of International Publication WO 98/14499 (Tg = 136 ° C.)
(3) PC (also called PC-1)
Panlite grade C-1400QJ (manufactured by Teijin Chemicals Ltd./Tg=158° C.)
(3 ′) PC-2
In a reactor equipped with a thermometer, a stirrer and a reflux condenser, 152400 parts of ion-exchanged water and 84320 parts of 25% aqueous sodium hydroxide solution were added, and 9,9-bis (4-hydroxy-3 having a purity of 99.8% by HPLC analysis. -Methylphenyl) fluorene (hereinafter sometimes abbreviated as “biscresol fluorene”) 34848 parts, 2,2-bis (4-hydroxyphenyl) propane 9008 parts (hereinafter sometimes abbreviated as “bisphenol A”) and After dissolving 88 parts of hydrosulfite, 178400 parts of methylene chloride was added, and 18248 parts of phosgene was blown in at a temperature of 15 to 25 ° C. over 60 minutes with stirring. After the completion of phosgene blowing, a solution obtained by dissolving 177.8 parts of p-tert-butylphenol in 2640 parts of methylene chloride and 10560 parts of 25% aqueous sodium hydroxide solution were added, and after emulsification, 32 parts of triethylamine was added and the mixture was heated at 28 to 33 ° C. The reaction was terminated by stirring for a period of time. After completion of the reaction, the product is diluted with methylene chloride, washed with water, acidified with hydrochloric acid, washed with water, and when the conductivity of the aqueous phase is almost the same as that of ion-exchanged water, the methylene chloride phase is concentrated and dehydrated to remove polycarbonate. A solution with a concentration of 20% was obtained. The polycarbonate (copolymer A) obtained by removing the solvent from this solution had a molar ratio of biscresol fluorene to bisphenol A of 70:30 (polymer yield 97%). In addition, this polymer had an intrinsic viscosity of 0.674 and a Tg of 226 ° C.
(4) Acrylic According to Production Example 1 of JP 2008-9378 A [0222] to [0224], synthesized from methyl methacrylate = 7500 g and methyl 2- (hydroxymethyl) acrylate, 2500% lactonization rate, Tg = 134 ° C. acrylic compound was obtained.
(5) Cellulose acylate resin a) CAP-1: a product using pellets described in Example 1 of JP-A-2008-87398
(Pr = 0.7 substitution, Ac = 1.95 substitution / KM patent)
B) CAP-2: Resin of Example 101 described in Table 3 of JP-A-2008-50562
(Pr = 2.55, Ac = 0.15)
C) CAP-3: Cellulose ester C described in Examples of JP-A-2008-197424
(Degree of acetyl substitution = 1.0, degree of substitution of propionyl = 1.2: Tg = 150 ° C.)
D) TAC: cellulose triacetate described in Example 1 of JP-A-2008-260921
(Degree of acetyl substitution = 2.84: Tg = 165 ° C.)
E) DAC: Cellulose acetate L-70 manufactured by Daicel Chemical Industries, Ltd.
(Degree of acetyl substitution = 2.43, Tg = 170 ° C.)

(Create dope)
(1) COC, COP
The resin was dissolved in a 1: 1 mixture (weight ratio) of toluene and n-hexane at 10% by weight (weight ratio of the resin to the amount of solvent). A stabilizer (Irganox 1010 manufactured by Ciba Geigy Co.) was added to the resin in an amount of 0.3% by weight.

(2) PC
JP, 10-239522, A Dope of solid content 18 mass% (weight ratio of the solid content to the amount of solvent) was prepared like paragraph number 0040 of Example 1 of the publication.
(2 ') PC-2
To 75 parts by mass of a mixed solvent of methylene chloride and ethanol containing 4 parts by mass of ethanol, 25 parts by mass of the polycarbonate (PC-2) was dissolved while stirring at 25 ° C. to obtain a transparent and viscous dope. .

(3) Acrylic A resin was dissolved in a mixed solvent of dichloromethane / acetone (weight ratio 80/20) at 20 wt% (weight ratio of resin to solvent amount). A stabilizer (Irganox 1010 manufactured by Ciba Geigy Co.) was added to the resin in an amount of 0.3% by weight.

(4) Cellulose acylate resin: CAP-1, CAP-2, DAC
In all of (i) to (e), 20% by weight of a resin in a mixed solvent of dichloromethane / methanol / butanol (90/8/2 weight ratio) (weight ratio of the resin to the amount of solvent), 8% by weight of the following optical adjusting agent, Plasticizers a), b), c) 9% (each 3% by weight) were added.

  However, the CAP-2 dope used in the present invention 52 was changed to 5 wt% resin, 1.6 wt% optical modifier, and 1.8 wt% plasticizer. In the CAP-2 dope used in the above, the resin amount was changed to 4.5% by weight, the optical adjusting agent amount was changed to 1.4% by weight, and the plasticizer amount was changed to 1.6% by weight.

Optical adjusting agent (compound of Japanese Patent Application Laid-Open No. 2008-76548 [Chemical Formula 4])
-Plasticizer a) Triphenyl phosphate b) Polymer A described in Table 2 of JP-A-2008-197424
c) Polymer C described in Table 2 of JP2008-197424A
(5) Cellulose acylate resin: CAP-3
According to the description in Example 1 of JP-A-2008-197424, a dope having a solid content of 31% by mass (a weight ratio of the resin to the amount of solvent) with respect to the solvent was prepared.
(6) Cellulose acylate resin: TAC
In accordance with the description in Example 1 of JP-A-2008-260921, a dope having a solid content of 27% by mass (a weight ratio of the resin to the amount of the solvent) with respect to the solvent was prepared.

<Film formation and application of the film of the first embodiment (not stretched and contracted perpendicular to the stretching direction)>
(Solution casting)
After filtering the dope with a 5 μm filter agent, the dope was extruded from a T die having a width of 1450 mm and a lip gap of 1 mm onto a support described in Tables 1 and 2 at an extrusion temperature of 260 ° C. (acrylic only 230 ° C.). Finally stripped. At this time, the clamping process was performed under the following conditions.
In the band method, two rolls (drive rolls) with a diameter of 1 m are installed 10 m apart, a stainless steel belt with a thickness of 3 mm is provided between them, and the dope is extruded from one die on one drive roll and immediately before making a full turn on the band. The dope (semi-fluid film) cast on was peeled off. The temperature of the semi-fluid film on the band was adjusted to a desired temperature by introducing temperature-controlled air into a casing installed around the band.
In the drum system, a dope was extruded from a die onto a stainless steel drum having a diameter of 1.5 m, and the dope (semifluid film) cast just before one round on the drum was peeled off. The temperature of the semi-fluid film on the drum was adjusted to a desired temperature by adjusting the temperature of the heat medium circulating in the drum.

(1) Clamping method Selected from the following and listed in Tables 1 and 2. In any embodiment, the cylinder was set so that the touch pressure described in Tables 1 and 2 was obtained.
(1-1) Roll and roll (described in R & R and Tables 1 and 2)
Use Hcr-plated metal rolls with a width of 1400 mm, a diameter of 300 mm, and an outer cylinder thickness as shown in Tables 1 and 2. Both rolls are hollow, and the temperature of the roll is adjusted by circulating a temperature-controlled heating medium. did. The pinching pressure was adjusted by adjusting the pressure between the rolls. Both rolls have the same width, diameter, and material.
(1-2) Roll and belt (R & B and listed in Tables 1 and 2)
Rolls B and B ′ having a width of 1500 mm and a diameter of 100 mm were brought into contact with an Hcr-plated metal roll A having a width of 1400 mm and a diameter of 300 mm and an outer cylinder thickness described in Tables 1 and 2. The roll B, the roll A, and the roll B ′ were arranged so that the angle connecting them was 90 degrees, and the roll B and B ′ were connected by a stainless steel belt having a thickness of 500 μm. The rolls B and B ′ have a hollow inside, and the temperature of the belt was adjusted by circulating a temperature-controlled heating medium. Similarly, the temperature of the roll A was controlled by passing a heating medium into the hollow interior. The pinching pressure was adjusted by adjusting the pressing of the rolls B and B ′ to the roll A. A stainless steel belt having a width of 1500 mm was used.
(1-3) Belt and belt (described in B & B and Tables 1 and 2)
Rolls A and A ′ having a width of 1400 mm and a diameter of 100 mm were positioned so that the distance between the centers of the rolls was 300 mm, and the space between them was connected by a stainless steel belt having a thickness of 500 μm. The rolls A and A ′ are hollow inside, and the temperature of the belt is adjusted by circulating a temperature-controlled heating medium. Another set of the same was made and contacted between these belts. The clamping pressure was adjusted by adjusting the pressure of these two pairs of rolls. A stainless steel belt having a width of 1500 mm was used.
(1-4) Roll and support (described in R & S and Tables 1 and 2)
A metal roll A having a width of 1400 mm, a diameter of 300 mm, and a thickness described in Tables 1 and 2 was brought into contact with the support. At this time, the temperature of the semi-fluid film was adjusted by adjusting the temperature of the roll A. The pinching pressure was adjusted by adjusting the pressure of the roll A. In addition, when the support was a band, the roll A was installed on a drive roll (the roll on which the dope was not cast).
(1-5) Belt and support (described in B & S and Tables 1 and 2)
Rolls A and A ′ having a width of 1400 mm and a diameter of 100 mm were arranged so that the distance between the centers of the rolls was 300 mm, and the space between them was connected by a stainless steel belt having a thickness of 500 μm. The rolls A and A ′ are hollow inside, and the temperature of the belt is adjusted by circulating a temperature-controlled heating medium. When the support was a band, the roll A was placed on a drive roll (the roll on which the dope was not cast).

(2) Clamping location Selected from the following and listed in Tables 1 and 2.
(2-1) Die outlet (Described as D in Tables 1 and 2)
A clamping device was installed on the die lip. Here, a pair of metal rolls having a diameter of 5 cm and an outer cylinder thickness described in Tables 1 and 2 was used. In Tables 1 and 2, the “outer cylinder thickness of the pinching body” column represents the outer cylinder thickness of the metal roll as the pinching body.
(2-2) Between die and support (in Tables 1 and 2 described as DS)
A clamping device was installed at an intermediate point between the die and the support.
(2-3) On support (shown as S on Tables 1 and 2)
In the case of the drum system, a clamping device was installed at the center between the dope attachment point and the peeling point, and on the drive roll on which the dope was not cast in the case of the band system.
(2-4) Between support and drying zone (in Tables 1 and 2, described as Sd)
A pinching device was installed in the center between the point of separation from the support of the semifluid film and the inlet of the drying zone.
(2-5) Drying zone (shown as d in Tables 1 and 2)
A semi-fluid was introduced into a drying zone set at 120 ° C. in the drying zone, and a clamping device was installed at a place where the residual solvent had a value shown in Tables 1 and 2.

(3) Clamping temperature By adjusting the temperature of the clamping body to the temperatures described in Tables 1 and 2, the viscosity of the semi-fluid film during clamping was set to the values described in Tables 1 and 2.

(4) Solidification After pinching, the semi-fluid film was solidified by the following method, and listed in Tables 1 and 2 as “dry” and “poor solvent”.
(4-1) Drying The semi-fluid film was introduced into a drying zone at 120 ° C. and dried for the time shown in Tables 1 and 2 to obtain the residual solvent films shown in Tables 1 and 2.
(4-2) Poor solvent immersion The semi-fluid film was immersed for 5 minutes in a mixed solution of water and methanol (50% by mass) each as a poor solvent at 20 ° C. and solidified, and then dried at 120 ° C. for 30 minutes. did.

(5) Winding These films were wound after trimming both ends and embossing (knurling) with a height of 30 μm at both ends. In all the levels, the width was 1.5 m and the winding length was 3000 m.

(Characteristic evaluation of film)
The characteristics of the films of each Example and Comparative Example were evaluated by the above methods and listed in Tables 1 and 2. In addition, the inclination direction which measured Re [+40 degree] and Re [-40 degree] of the film of this invention was all the longitudinal direction of the film.

(Film cross-section slow axis)
Next, the same measurement as in the extinction position measurement method was performed except that a retardation plate A having a specific phase difference was inserted in the 45 ° azimuth between the upper polarizing plates, and the slow axis of the film piece of Example 1 (this specification) The change in the cross-sectional slow axis) and the magnitude of birefringence were measured. As the retardation plate A, a λ / 4 plate, a λ / 2 plate, and a λ plate were used, and the magnitude of birefringence was measured in comparison with an interference color chart. As a result, it was surprisingly found that the cross-sectional slow axis changed in the thickness direction, and the birefringence changed in the thickness direction. Moreover, it was confirmed that the film of Example 1 was distributed at an angle where the slow axis of the cross section was different by 5 ° or more in the thickness direction.

(Composition gradient in the thickness direction)
The composition gradient in the thickness direction of the film of each example and comparative example was measured by the following method.
The film is cut in the cross-sectional direction, and a section having a thickness of 1 μm is prepared. In contrast, microscopic IR analysis is performed as follows.
(1) Adjust the aperture of the microscopic IR to a rectangle of 5 μm × 20 μm.
(2) The IR measurement is performed between 500 cm-1 and 4000 cm-1 from one surface side to the other surface side while shifting each 5 μm so that the side of 20 μm is parallel to the film surface.
(3) The IR spectrum spectrum of the center thickness is S (0), the strongest absorbance peak is A, the absorbance is α (0), and the peak position is acm-1.
(4) The IR spectrum measured from the center thickness spectrum toward one surface is S (i), and the IR spectrum measured toward the other surface is S (−i) (i = a positive integer) 1,2,3 ...). The difference spectrum between S (i) and S (0) is carried out as in the following equation, and the coefficient b in the following equation is adjusted so that the absorbance of the difference spectrum acm-1 is zero. The strongest absorbance in this difference spectrum is C (i). This is obtained from one surface to the other surface, and an average value of absolute values of C (i) is obtained (referred to as C (i) av).
formula:
S (0) −S (i) × b = 0
(5) A sample having C (I) av / α (0) of 0.05 or more was defined as “with composition gradient”.

(Peeling failure)
Moreover, the peeling failure of the film of each Example and a comparative example was measured with the following method.
• Make 11 cuts on one side of the film at intervals of 3 mm, with a double-edged razor. Eleven incisions are made in the same manner at intervals of 3 mm in the direction perpendicular to this to make 10 × 10 squares.
-Adhesive tape (polyester adhesive tape No. 31B manufactured by Nitto Denko) is attached to this, and the surface is thoroughly rubbed and adhered, and then the tape is peeled off at once.
-Count the squares from which the film surface peeled, and use this as the rate of peeling failure.
-Repeat the above measurement on the opposite side of the film in the same way to determine the rate of peeling failure.
These average values are shown in Tables 1 and 2.

(Circular litter dance)
The circular retardance of the example films was measured by the method described herein. As a result, the film of any example exceeded 5 nm.

  In Tables 1 and 2, the “semifluid film temperature at the time of clamping” was the same as the temperature of the clamping body at the time of clamping. That is, the temperature of the pinching body was set and controlled so as to have the semi-fluid film viscosity at the time of the pinching. In the “-” in the “Outer cylinder thickness of the pinching body”, a belt having a thickness of 0.8 mm was used as the pinching body and a roll was used.

From Tables 1 and 2, Examples 1 to 4 and Comparative Examples 1 and 2 compare the effects of pinching. Examples 5 to 8 and Comparative Examples 3 and 4 examine the effect of the viscosity of the semi-fluid film during clamping. In Examples 9 to 10 and Comparative Examples 5 and 6, the effect of the residual solvent amount was examined. Examples 11 to 16 examine the effect of the temperature of the semi-fluid film during clamping. Examples 17-21 show the effect of the thickness of the roll used for the pinching body. Examples 22 to 26 examine the effect of the temperature of the support. Examples 27 to 31 show the expression of γ due to the peripheral speed difference of the pinching body. Examples 32 and 33 show the effect of the location of the pinching body and the amount of solvent during pinching. Examples 34-38 compare the pinching methods. Examples 39 to 44 show the expression of Re [0 °] and Rth. In Examples 45 to 51, more preferred embodiments are increased one by one to see the synergistic effect. Examples 52 and 53 examine the effect of the amount of solvent at the time of clamping. Examples 54 and 55 are comparative examinations of solidification methods (drying and immersion in a poor solvent). Comparative Example 7 is the result of Japanese Patent Application Laid-Open No. 10-239522 using a conventional stretching method, and Example 56 is an example in which the present invention was carried out under conditions close thereto. In addition, in order to match the conditions of the publication example, the drying temperature was set to 100 ° C. in Comparative Example 7 and Example 56.
Moreover, none of the films of Examples 1 to 56 and Comparative Examples 1 to 7 had a composition gradient in the film thickness direction.
According to the first aspect of the present invention, it was found that a stretched film with few peeling failures could be provided by a simple method.

(Polarizer)
A polarizing plate was produced using the produced films of Examples 1 to 56. Specifically, first, iodine was adsorbed to a stretched polyvinyl alcohol film to prepare each polarizing film. Using these polarizing films, an 80 μm TAC film (manufactured by FUJIFILM Corporation), a uniaxially stretched norbornene polymer film, and a λ / 2 plate with Re = 270 nm, as shown in FIG. 1, Examples 1 to 56 films were laminated. In this manner, two polarizing plates each using the films of Examples 1 to 56 were produced.

(LCD panel)
The films of Examples 1 to 56 were installed as a viewing angle compensation film between a pair of polarizing plates and a liquid crystal plate. Moreover, the polarizing plate using the film of Examples 1-56 was arrange | positioned at the upper and lower sides of the liquid crystal cell. When a liquid crystal display panel having a TN, ECB, OCB, VA, or IPS mode was used, all exhibited good viewing angle compensation performance.

[Examples 101 to 139, Comparative examples 101 to 108, Reference examples 101 to 106]
<Film formation and application of the film of the second embodiment (stretched and contracted perpendicular to the stretching direction)>
Next, in the film formation of the film of the first embodiment, the film of the second embodiment was formed in the same manner except that the film was stretched and contracted before the semifluid film was solidified in the following embodiment.

(I) Clamping and Stretching Procedure After peeling from the drum and band, the crushing and stretching procedures were selected from the following procedures for each level (described in Table 3) and subjected to stretching and clamping. The viscosity of the semi-fluid shown in Table 3 was adjusted by adjusting the drying time and temperature on the drum and band and during stretching.
Procedure (i): “lateral stretching + longitudinal shrinkage” → clamping pressure → lateral stretching
Procedure (ii): “lateral stretching + longitudinal contraction” → clamping procedure (iii): lateral stretching → clamping procedure (iv): clamping process (v): clamping pressure → “lateral stretching + longitudinal contraction”

(II) Nipping pressure and stretching conditions (II-1) Nipping pressure Nipping pressure and roll thickness described in Table 3 were used.
(II-2) "lateral stretching + longitudinal shrinkage"
The temperature and magnification described in Table 3 were used. The magnification is a value obtained by dividing the length before stretching by the length after stretching, and less than 1 means contraction. In addition, “lateral stretching + longitudinal shrinkage” was selected from the following and listed in Table 3.
Method (1): After transverse stretching, the clip of the tenter was removed and the stretched film was placed in the heat treatment zone, and the conveyance speed of the nip roll at the outlet was slower than that at the inlet nip roll. At this time, 10 rolls arranged so that the roll wrap length (W) / inter-roll length (G) were 0.2 were conveyed. Each roll had a diameter of 40 cm and a wrap angle of 120 °.
Method (2): Using a chuck provided with a pulley in the conveying (longitudinal) direction, it was contracted longitudinally after transverse stretching. The amount of longitudinal shrinkage was achieved by adjusting the tension of the winder at the tenter outlet.
Method (3): This was achieved by using a simultaneous biaxial stretching machine (trade name FITZ) manufactured by Ichikin Kogyo Co., Ltd. and slowing down the chuck conveying speed during stretching.
Method (4): It was carried out according to the method described in Example 2 of JP-A-9-138307 (longitudinal shrinkage during transverse stretching with a tenter).
Method (5): This was achieved by contracting the pantograph in the longitudinal direction using an apparatus conforming to the stretching apparatus disclosed in Japanese Patent Application Laid-Open No. 2008-44339.

(II-3) Transverse stretch It implemented using the tenter at the temperature and magnification of Table 3.

(Characteristic evaluation of film)
The properties of the films of each Example and Comparative Example were evaluated by the above methods and listed in Table 3.
Table 3 shows the maximum extinction angle and the minimum extinction angle expressed in one observation point with “/” between them. (“Inclination angle” described in Table 2 of JP 2010-61091 A is indicated by “˜”, but is different from this. That is, JP 2010-61091 A describes in paragraph [0148]. Thus, the variation of the measurement points in the longitudinal direction sampled at 10 points from the sample length of 30 to 39 m is shown, and the distribution in one measurement point is not shown as in the present invention. In Japanese Patent No. 61091, measurement is performed by “KOBRA” as described in paragraph [0148]. In this method, only one inclination angle data can be obtained for one measurement point, and one observation as in the present invention is performed. It does not show the distribution of a plurality of inclination angles in the cross-sectional direction at points, but is essentially different from the present invention.
When Re [0 °] is a positive value, it indicates that the slow axis exists in TD, and when it is negative, it indicates that the slow axis exists in MD. When Rth is a positive value, it indicates that the orientation is proceeding in the film plane, and negative indicates that the orientation is proceeding in the normal direction of the film surface.
The distributions of γ, Re [0 °], and Rth were measured by the following procedure and listed in Table 3. The larger the value, the lower the optical uniformity, and the stronger the unevenness when used as an optical compensator.
-Γ, Re [0 °], and Rth were measured by the above method over the entire width at intervals of 10 cm in the width direction.
・ Determine the “γ distribution” according to the following formula.
γ distribution (%) = maximum γ value−minimum γ value Re [0 °] distribution (%) = maximum Re [0 °] value−minimum Re [0 °] value Rth distribution (%) = maximum Rth value -Minimum Rth value

The wrinkles accompanying heat shrinkage were measured by the following method, and the results are shown in Table 3.
-Sample the film 1 meter long across the entire width.
-Put this in an oven at 100 ° C for 10 minutes under no tension.
・ Place this on a flat, smooth table and visually count the number of irregularities on the tin plate.

  In Table 3, “semi-fluid film temperature during clamping” was the same as the temperature of the clamping body during clamping. That is, the temperature of the pinching body was set and controlled so as to have the semi-fluid film viscosity at the time of the pinching. In the “-” in the “Outer cylinder thickness of the pinching body”, a belt having a thickness of 0.8 mm was used as the pinching body and a roll was used.

Examples 101 to 104 and Comparative Examples 101 and 102 in Table 3 show the effect of pinching pressure. Examples 105-108 and Comparative Examples 103 and 104 show the effect of the viscosity of the semi-fluid during clamping. Examples 109 to 110 and Comparative Examples 105 and 106 show the effect of residual solvent. Examples 111 to 113 and Reference Examples 101 and 102 show the effects of the procedures of pinching, transverse stretching, and longitudinal shrinkage. Examples 114-118 show the effect of the roll thickness of the pinching body. Examples 119 to 121 and Reference Examples 103 and 104 show the effect of the transverse draw ratio. Examples 122 to 124 and Reference Examples 105 and 106 show the effect of longitudinal contraction magnification. Examples 125-129 show the effect of the peripheral speed difference of the body during clamping. Examples 130-135 show the synergistic effect when increasing the preferred modes in order. Examples 136 to 137 show the effect of the solidification method. Example 138 shows a comparison with Comparative Example 107 that was further tested in accordance with the present invention A of the example of Japanese Patent Laid-Open No. 2020-61091. Example 139 shows a comparison with Comparative Example 108, which was further tested in accordance with Example F-1 of JP-A-6-222213.
According to the second aspect of the present invention, it has been found that a film that hardly causes wrinkles by heat treatment or the like can be provided by a simple method. Moreover, it turned out that the film with little optical nonuniformity was able to be provided by the more preferable aspect of the 2nd aspect of this invention.
In addition, it confirmed that the composition gradient of the thickness direction did not exist in any Example, a comparative example, and a reference example.

(Preparation of polarizing plate)
A 120 μm thick polyvinyl alcohol film was immersed in an aqueous solution containing 1 part of iodine, 2 parts of potassium iodide, and 4 parts of boric acid, and stretched 4 times at 50 ° C. to obtain a polarizing film. Next, Konica Minoltac KC8UX was immersed in a 2 mol / liter sodium hydroxide solution at 60 ° C. for 1 minute, further washed with water and dried, and then adhered to both sides of the polarizing film with a polyvinyl alcohol adhesive having a solid content of 2% by mass. Together, a polarizing plate was produced.

(Evaluation by liquid crystal display)
A 15-inch display Multi Sync LCD1525J manufactured by NEC was used after removing the optical compensation film and the polarizing plate that had been bonded in advance.

About the optical compensation film of the said sheet | seat, it has arrange | positioned together with the polarizing plate on both surfaces of the liquid crystal cell. The liquid crystal display device is set to white display on the entire surface, and the area of the area where color unevenness and density unevenness can be recognized is obtained in a completely dark room, and this is divided by the entire screen area and displayed as a percentage. did.
From Table 3, it was found that the liquid crystal display device using the film of the second aspect of the present invention had small display unevenness.

Claims (30)

A film containing a resin and containing 0.01 to 3% by mass of a solvent,
A section of the film including the tilt direction and thickness direction in the plane is placed between two polarizing plates arranged in crossed Nicols, and light is irradiated from both directions to both surfaces of the two polarizing plates. However, the extinction position observed when the film piece is rotated in the range of 0 ° to 90 ° differs depending on the distance from one end of the film piece in the thickness direction.   2. The film according to claim 1, wherein extinction positions are observed at different angles within a range of 5 ° to 90 ° depending on a distance in a thickness direction from one end of the film piece.   The film according to claim 1 or 2, wherein the first observed extinction position and the last observed extinction position differ by 5 ° or more when the film slice is rotated. A film containing a resin and containing 0.01 to 3% by mass of a solvent,
A film having a circular letter length of more than 5 nm measured at a wavelength of 550 nm measured from a direction inclined by 40 ° from the normal in a plane including a direction perpendicular to the film tilt direction and a film normal. The film according to any one of claims 1 to 4, wherein the following formulas (I) and (II) are satisfied.
30 nm ≦ Re [0 °] ≦ 600 nm (I) Formula (In Formula (I), Re [0 °] represents retardation in the in-plane direction at a wavelength of 550 nm measured from the film normal direction).
−600 nm ≦ Rth ≦ 600 nm (II) Formula (In Formula (II), Rth represents retardation in the thickness direction at a wavelength of 550 nm.) The film according to any one of claims 1 to 5, wherein the following formula (III) is satisfied.
30 nm ≦ γ ≦ 600 nm (III) Formula γ = | Re [+ 40 °] −Re [−40 °] | (III) In the formula (Formula (III) ′, Re [+ 40 °] is the film tilt direction and the film method. In the plane including the line, it represents retardation in the in-plane direction at a wavelength of 550 nm measured from a direction inclined to the tilt azimuth side by 40 ° with respect to the normal, and Re [−40 °] is relative to the normal Represents retardation in the in-plane direction at a wavelength of 550 nm measured from a direction tilted by −40 ° toward the tilt direction.) Distribution of (gamma) shown by following formula (VI) is 1-30 nm, The film as described in any one of Claims 1-4 characterized by the above-mentioned.
γ distribution = maximum value of γ measured in the width direction−minimum value of γ measured in the width direction (VI)
γ = | Re [+ 40 °] −Re [−40 °] | (VI) ′
(In the formula (VI) ′, Re [+ 40 °] is an in-plane at a wavelength of 550 nm measured from a direction inclined to the tilt azimuth side by 40 ° with respect to the normal in a plane including the film tilt azimuth and film normal. (Re [−40 °] represents the retardation in the in-plane direction at a wavelength of 550 nm measured from the direction inclined by −40 ° to the tilt direction with respect to the normal line.)   The film according to claim 7, wherein there is a slow axis in the width direction. The film according to claim 7 or 8, which satisfies the following formulas (VII) and (VIII):
0 nm ≦ Re [0 °] ≦ 200 nm (VII) Formula −50 nm ≦ Rth ≦ 300 nm (VIII) Formula (In the formula (VII), Re [0 °] is the plane including the film tilt direction and the film normal. Represents in-plane retardation at a wavelength of 550 nm measured from the normal direction.) The film according to any one of claims 7 to 9, wherein the following formula (IX) is satisfied.
30 nm ≦ γ ≦ 200 nm (IX) formula γ = | Re [+ 40 °] −Re [−40 °] | (IX) ′ formula (in the formula (IX) ′, Re [+ 40 °] is the film tilt direction and the film method. In the plane including the line, it represents retardation in the in-plane direction at a wavelength of 550 nm measured from a direction inclined to the tilt azimuth side by 40 ° with respect to the normal, and Re [−40 °] is relative to the normal Represents retardation in the in-plane direction at a wavelength of 550 nm measured from a direction tilted by −40 ° toward the tilt direction.)   The film according to claim 1, wherein the concentration of the resin is uniform in the film thickness direction.   The film according to claim 1, wherein the film contains an additive, and the concentration of the additive is uniform in the film thickness direction.   The film according to claim 1, wherein the resin is a thermoplastic resin. Extruding a dope containing a resin and a solvent as a semi-fluid film from a supply means;
Casting an extruded semi-fluid film on a support;
Peeling the cast semi-fluid film from the support;
Drying the peeled semi-fluid film;
A step of controlling the amount of residual solvent to 0.01 to 3% by mass;
The semi-fluid film having a viscosity of 1 Pa · s to 100,000 Pa · s is continuously passed between the first clamping surface and the second clamping surface constituting the clamping device while applying a clamping pressure of 20 MPa to 500 MPa. The manufacturing method of the film characterized by including the process of pinching.   The method for producing a film according to claim 14, wherein a semi-fluid film having a solvent amount of 30% by mass to 1000% by mass with respect to the solid content is sandwiched.   The method for producing a film according to claim 14 or 15, wherein the support is a drum or a band.   The method for producing a film according to any one of claims 14 to 16, wherein the semi-fluid film is sandwiched between the outlet of the supply means and the support.   The method for producing a film according to any one of claims 14 to 17, wherein a moving speed of the first pressing surface is made faster than a moving speed of the second pressing surface. The ratio of the moving speed difference between the first clamping surface and the second clamping surface of the clamping device defined by the following formula (V) to the speed of the first clamping surface is 0.5 to 20%. The manufacturing method of the film as described in any one of Claims 14-18.
Formula (V)
Difference in moving speed (%) = 100 × {(moving speed of first pressing surface) − (moving speed of second pressing surface)}
/ (Moving speed of the first clamping surface)   The film according to any one of claims 14 to 19, wherein at least one of the first clamping surface and the second clamping surface is a surface of a metal touch roll having an outer cylinder thickness of 6 to 45 mm. Production method.   The said clamping apparatus contains two rolls, The 1st clamping surface and the 2nd clamping surface are the surfaces of each roll, The film of any one of Claims 14-20 characterized by the above-mentioned. Production method.   The said support body is controlled to -40 degreeC-15 degreeC, The manufacturing method of the film as described in any one of Claims 14-21 characterized by the above-mentioned. After the step of clamping the semi-fluid film,
23. The method according to any one of claims 14 to 22, comprising at least one of a step of volatilizing and solidifying the solvent in the semifluid film and a step of immersing and solidifying the semifluid film in a poor solvent. The manufacturing method of the film as described in any one. The film production according to any one of claims 14 to 23, comprising a step of stretching the semifluid film at a stretch ratio of X times and a step of shrinking Y times in a direction orthogonal to the stretch direction. Method.
1.00 <X <2.50
0.40 <Y <1.00   The method for producing a film according to claim 24, wherein the stretching is stretching in a direction perpendicular to the transport direction.   The method for producing a film according to claim 24 or 25, wherein the stretching step is performed before the pinching.   The method for producing a film according to any one of claims 14 to 26, wherein the resin is a thermoplastic resin.   A film produced by the method for producing a film according to any one of claims 14 to 27.   A polarizing plate using a polarizer and at least one film according to any one of claims 1 to 13 and 28.   A liquid crystal display device using at least one film according to any one of claims 1 to 13 and 28.