JP2003248117A - Phase difference plate, circular polarizing plate and manufacturing method of each for liquid crystal displace element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a phase difference plate (particularly, a λ/4 plate having a phase difference of λ/4 in a wide wavelength area) superior in visual field characteristics. <P>SOLUTION: In a manufacturing method of the phase difference plate characterized to be the phase difference plate, a water content rate of a long cellulose acetate film is adjusted so as to be 2.0 mass% or more and less than 20.0 mass%. A retardation value (Re450) measured at a wavelength of 450 nm is 60 or 135 nm, and a retardation value (Re590) measured at a wavelength of 590 nm is 100 or 170 nm. The relation of 2 nm≤Re590-Re450≤100 nm is satisfied. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a retardation plate (particularly a λ / 4 plate) made of cellulose acetate and a method for manufacturing a circularly polarizing plate. The present invention also relates to a method for manufacturing a liquid crystal display device using a circularly polarizing plate made of cellulose acetate.

[0002]

2. Description of the Related Art Generally, a liquid crystal display device is composed of a liquid crystal cell, a polarizing plate and a retardation plate. The liquid crystal cell is composed of rod-shaped liquid crystalline molecules, two substrates for enclosing the rod-shaped liquid crystalline molecules, and an electrode layer for applying a voltage to the rod-shaped liquid crystalline molecules.
Various modes of liquid crystal cells are known, depending on the alignment state of rod-shaped liquid crystalline molecules. For the transmissive type that uses a backlight as a light source, TN (Twisted Nematic), IPS (I
n-Plane Switching, FLC (Ferroelectric Liquid)
Crystal), OCB (Optically Compensatory Ben)
d), STN (Supper Twisted Nematic), VA (Verti
Cally Aligned), reflective type that uses outside light as a light source by using a reflector, TN, HAN (Hy
Display modes such as brid Aligned Nematic) have been proposed. A polarizing plate is generally composed of a polarizing film and a transparent protective film, and this polarizing film is generally obtained by impregnating polyvinyl alcohol with an aqueous solution of iodine or a dichroic dye, and further uniaxially stretching the film. To be
It has a structure in which two transparent protective films are attached to both sides of this polarizing film.

The retardation plate is used in various image display devices and liquid crystal display devices in order to eliminate image coloring and expand the viewing angle. In particular, the λ / 4 plate is used in a reflective liquid crystal display device or a semi-transmissive liquid crystal display device, and it is proposed that it may be used as an antireflection film of an EL element in the future. Japanese Patent Laid-Open No. 2000-37116, W
In O00 / 65384 and WO00 / 26705, there is a description regarding application to a retardation plate, a circularly polarizing plate, and a reflective liquid crystal display device in which a polymer film has a smaller retardation as the measurement wavelength is shorter. In each case, λ / 4 is realized in a wide wavelength range.

On the other hand, a circularly polarizing plate is obtained by laminating a λ / 4 plate and a polarizing plate, and in the case of using a λ / 4 plate consisting of one film described above, a retardation phase of the λ / 4 plate is used. The layers are laminated with the angle formed by the axial direction and the absorption axis direction of the polarizing plate being substantially 45 °. Substantially 45 ° means 45 ± 10 °, preferably 45 ± 5 °. The exact angle differs depending on the display system of the liquid crystal display device, and the optimum angle is selected for each display system. Japanese Patent Laid-Open No. 2000-137
116 publication, WO00 / 65384, WO00 / 26
Since all the λ / 4 plates disclosed in 705 are films uniaxially stretched in the longitudinal direction or the vertical direction of the roll, the λ / 4 plate is substantially 4
It was necessary to cut it out at an angle of 5 ° and attach it to a polarizing plate. In addition, it was necessary to adhere the angles strictly, and the yield was poor. Further, it has been difficult to use a λ / 4 plate made of cellulose acetate as a protective film for a polarizing plate to achieve a thin film. Therefore, roll-to-roll manufacturing has been desired.

In order to solve this problem by using a usual polarizing plate manufacturing method, a retardation plate stretched in a direction oblique to the longitudinal direction of the film is required. Several methods have been proposed for inclining the orientation axis of the polymer at a desired angle with respect to the film transport method. For example, JP 20
In Japanese Patent Application Laid-Open No. 00-9912, while uniaxially stretching a plastic film laterally or longitudinally, the left and right of the stretching direction are stretched at different speeds in a longitudinal or lateral direction different from the preceding stretching direction, and the orientation axis is uniaxially stretched. It has been proposed to tilt with respect to the stretching direction. However, in this method, for example, when a tenter system is used, it is necessary to make a difference in conveyance speed between the left and right sides, which causes creases and film deviation, which makes it difficult to obtain a desired inclination angle (45 °). If it is attempted to reduce the left-right speed difference, the stretching process must be lengthened, and the equipment cost becomes very large.

In Japanese Patent Laid-Open No. 3-182701,
The continuous film has a pair of left and right film holding points that make an angle of θ with the running direction at the left and right edges of the continuous film, and as the film runs, the mechanism that allows each pair of points to be stretched in the direction of θ A method for producing a film having a stretching axis at an arbitrary angle θ with respect to the direction has been proposed. However, even in this method, the film advancing speed changes depending on the left and right of the film, so that the film has cracks and wrinkles, and in order to mitigate the wrinkles, it is necessary to lengthen the stretching process extremely, and there is a drawback that the equipment cost increases. It was

In Japanese Patent Laid-Open No. 2-113920, both end portions of a film are gripped between two rows of chucks traveling on a tenter rail arranged so that the traveling distances of the chucks in a predetermined traveling section are different. A manufacturing method has been proposed in which the film is stretched in a direction oblique to the length direction of the film by running the film. However, even in this method, cracks and wrinkles were generated when crossed obliquely, which was inconvenient for an optical film.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a retardation plate having an excellent viewing angle characteristic (particularly, a λ / 4 plate having a retardation of λ / 4 in a wide wavelength range). To do. Furthermore, it is an object of the present invention to manufacture a circularly polarizing plate and a liquid crystal display device having excellent productivity.

[0009]

The objects of the present invention have been achieved by the following items (1) to (17). (1) A long cellulose acetate film is adjusted to have a water content of 2.0% by mass or more and 20.0% by mass or less, and stretched in a direction that is neither parallel nor perpendicular to the longitudinal direction. Thus, the retardation value (Re450) measured at a wavelength of 450 nm is 60 to 135 nm, the retardation value (Re590) measured at a wavelength of 590 nm is 100 to 170 nm, and the relationship of 2 nm ≦ Re590-Re450 ≦ 100 nm is satisfied. A method of manufacturing a retardation plate, characterized in that the retardation plate is formed as described above. (2) The method for producing a retardation plate according to (1), wherein the retardation plate is stretched at 45 ± 10 ° with respect to the longitudinal direction. (3) The refractive index nx in the in-plane slow axis direction of the retardation plate, the refractive index ny in the direction perpendicular to the in-plane slow axis, and the refractive index nz in the thickness direction are 1 ≦ (nx−nz). / (Nx-ny) ≦
The manufacturing method according to (1) or (2), which is drawn so as to satisfy the relationship of 3. (4) The method for producing a retardation film according to (1) to (3), wherein the cellulose ester film contains a compound having at least two aromatic rings as a retardation adjusting agent. (5) The method for manufacturing a retardation plate according to (1) to (4), wherein the stretching is performed in water. (6) The method for producing a retardation plate according to (1) to (4), wherein the stretching is performed in water vapor having a relative humidity of 60% or more and 100% or less. (7) The method for producing a retardation film described in (1) to (4), wherein the cellulose ester film is swollen in water and then stretched in air. (8) The method for producing a retardation plate according to (1) to (7), wherein the stretching is performed at 50 ° C. or higher and 150 ° C. or lower. (9) The method for producing a retardation plate according to (1) to (8), wherein the stretching is performed for 1 second or more and 2 minutes or less. (10) The method for producing a retardation plate according to (1) to (9), wherein the stretching is performed at a draw ratio of 1.1 times or more and 2.5 times or less.

(11) A method for producing a long circular polarizing plate by laminating a long linear polarizing film and a long retardation plate so that their longitudinal directions are parallel to each other, Linear polarizing plate is a long linear polarizing film whose transmission axis is substantially parallel to its longitudinal direction, and the long retardation plate is
By adjusting the water content of the long cellulose acetate film to 2.0% by mass or more and 20.0% by mass or less, and stretching the film in a direction that is neither parallel nor perpendicular to the longitudinal direction, The retardation value (Re450) measured at a wavelength of 450 nm is 60 to 135 nm, and the wavelength 59
A method for producing a circularly polarizing plate, which is a retardation plate having a retardation value (Re590) measured at 0 nm of 100 to 170 nm and satisfying a relationship of 2 nm ≦ Re590-Re450 ≦ 100 nm. (12) The method for manufacturing a circularly polarizing plate according to (11), wherein the retardation plate is manufactured by the manufacturing method according to (2) to (10). (13) The method for producing a circularly polarizing plate according to (11) or (12), further comprising a protective film laminated on the side opposite to the retardation plate of the linear polarizing film.

(14) Manufacture of an image display device characterized in that a long circular polarizing plate manufactured by the manufacturing method described in (11) to (13) is attached to a transparent substrate made of glass or plastic. Method. (15) In the mother glass cell filled with liquid crystal (11)
A method for manufacturing a liquid crystal display device, which comprises laminating the long circular polarizing plate according to any one of (1) to (13). (16) A liquid crystal display device, characterized in that the liquid crystal display device manufactured by the method according to (14) or (15) is used in a reflective liquid crystal display device or a transflective liquid crystal display device. (17) A liquid crystal display device manufactured by the method according to (14) or (15) is manufactured by using a TN display method, an ECB method, or a VA display method.
A liquid crystal display device characterized by being used in a liquid crystal display device of the HAN system.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention produces a retardation film stretched in a direction that is neither parallel nor perpendicular to the longitudinal direction of the film. As a result of intensive investigations by the present inventors, cellulose acetate used as a material has a poor stretchability and a small Re-expressing property, and therefore, there is a problem that Re has to be achieved with a thick film in a conventionally known dry stretching. It turned out to occur. It was also found that uneven thickness occurs. In the present invention, in order to solve these problems and achieve the objects, a λ / 4 plate is manufactured by making a tack contain water and stretching it in a direction that is neither parallel nor perpendicular to the longitudinal direction.

[Water Content] The cellulose acetate film has a water content of 1.8% at room temperature. In the present invention, such a cellulose acetate film (raw fabric) is hydrated before stretching, and has a water content of 2.0% by mass or more and 20.0% by mass or less,
More preferably 2.5 mass% or more and 18.0 mass% or less,
More preferably, the amount is 3.0% by mass or more and 16.0% by mass or less.

The water content is the mass fraction (%) of water contained in the film, and actually the water content (μ
When g) is W and the sample amount weighed is F (mg), the water content (mass%) = 0.1 × (W / F).
The water content of the cellulose acetate film during stretching is 2.
When the content is 0% by mass or more and 20.0% by mass or less, the glass transition temperature (Tg) can be lowered, and uniform stretching can be performed at a temperature lower than the normal dry stretching temperature (130 ° C.).

[Stretching Method] In order to control the water content of the film during stretching, the film may be immersed in water before stretching, or may be conditioned at a constant temperature and high humidity. Also, these two may be used in combination. When immersed in a water tank, the temperature of water is preferably 50 ° C or higher and 100 ° C or lower, more preferably 60 ° C or higher and 95 ° C or lower, and particularly preferably 70 ° C or higher and 90 ° C or lower. Immersion time is 5 seconds or more 10
It is preferably within minutes, more preferably within 10 seconds and within 8 minutes, and particularly preferably within 20 seconds and within 6 minutes. When the humidity is controlled with constant temperature and high humidity, the temperature is preferably 50 ° C or higher and 150 ° C or lower, more preferably 60 ° C or higher and 140 ° C or lower, and particularly preferably 70 ° C or higher and 120 ° C or lower. Relative humidity is 60% RH
It is preferably 100% RH or less and 100% or less.

The water used for the immersion and steam aeration may be substantially water. Substantially water refers to a substance composed of 60% by mass or more of water, and other than water, an organic solvent, a plasticizer,
A surfactant or the like may be included. Examples of preferable organic solvents include water-soluble organic solvents having 1 to 10 carbon atoms. However, more preferably 90% by mass or more is water, further preferably 95% by mass or more is water, and most preferably pure water is used. The water used in the following description may be substantially water.

The stretching atmosphere may be air, water vapor, or water. The air in the stretching atmosphere means stretching in an atmosphere in which the temperature is controlled and the humidity is not controlled. The stretching temperature is preferably 50 ° C or higher and 150 ° C or lower, more preferably 60 ° C or higher and 130 ° C, and particularly preferably 65 ° C or higher and 110 ° C or lower. The fact that the atmosphere during stretching is in water vapor means that the temperature and humidity are constant or that water vapor is applied to the film. The stretching temperature is preferably 50 ° C or higher and 150 ° C or lower, more preferably 60 ° C or higher and 140 ° C or lower, and 70
It is particularly preferable that the temperature is not lower than 130 ° C and not higher than 130 ° C. 60% relative humidity
RH or more and 100% RH or less is preferable. By doing so, the water content in cellulose acetate is 2.0% by mass.
Above 20.0 mass% is maintained. Moisture content is 2.0
When it is less than mass%, the elongation at break becomes small at the time of stretching and it becomes easy to break, and the retardation Re550 measured at a wavelength of 550 nm does not reach λ / 4.

When the atmosphere during stretching is in water, it means that the film is stretched while being immersed in a water tank. The water temperature is preferably 50 ° C or higher and 100 ° C or lower, and 60 ° C or higher and 9 ° C or higher.
8 ° C. or lower is more preferable, and 65 ° C. or higher and 95 ° C. or lower is particularly preferable. The immersion time is preferably 0.5 seconds or more and 10 minutes or less, more preferably 1 second or more and 8 minutes or less, and particularly preferably 1 second or more and 7 minutes or less.

The water content immediately after stretching is 2.0% by mass or more 2
It is preferable to keep the content at 0.0 mass% or less so that the film can be stretched uniformly. Since the water content of the film is controlled to 2.0% by mass or more and 20.0% by mass or less in the step immediately before stretching, if the water content is 2.0% by mass or less, the elongation at break becomes small, which is a desired value. The front retardation cannot be obtained up to the λ / 4 region due to the thickness. Here, the water content immediately after stretching refers to the water content of the film immediately after the stretching step. Further, after passing through the stretching step, water adhering to the film may be removed before reaching the winding portion. Known methods such as an air knife method and a blade method can be used.

1 and 2 are schematic plan views showing an example of the method of the present invention in which the film is stretched obliquely with respect to the longitudinal direction. The stretching method of the present invention comprises a step of introducing a long raw fabric film shown in (a) in the direction of arrow (a), a width direction stretching step shown in (b), and a stretching step shown in (c). It includes the next step of feeding the film, that is, the step of feeding in the (b) direction. Hereinafter, when referred to as a "stretching step", these steps (a) to (c) are included. The film is continuously introduced from the direction (a), and is first held by the holding means on the left side as viewed from the upstream side at point B1. At this point, one film edge is not held yet, and no tension is generated in the width direction. That is, the point B1 does not correspond to the substantial holding start point (hereinafter referred to as “substantial holding start point”) of the present invention. In the present invention, the substantial retention start point is defined as the point where both ends of the film are retained for the first time. The substantial holding start point is a holding start point A1 on the more downstream side, and a straight line drawn from A1 substantially perpendicularly to the center line 11 (FIG. 1) or 21 (FIG. 2) of the introduction side film is the holding means on the opposite side. It is indicated by two points C1 that intersect the locus 13 (FIG. 1) or 23 (FIG. 2). Starting from this point, when the holding means at both ends is conveyed at substantially the same speed, A1 moves to A2, A3 ... An, and C1 similarly moves to C2, C3 ... Cn every unit time. That is, the straight line connecting the points An and Cn through which the holding means serving as the reference passes at the same point is the stretching direction at that time.

In the method of the present invention, as shown in FIGS.
Since n gradually lags behind Cn, the stretching direction is gradually inclined from the direction perpendicular to the transport direction. The substantial holding release point of the present invention (hereinafter referred to as “substantial holding release point”) is a Cx point that is released from the holding means at a more upstream side, and a center line 12 of the film sent from Cx to the next step (FIG. 1). Or 22
A straight line drawn substantially perpendicular to (FIG. 2) is defined by two points Ay intersecting the trajectory 14 (FIG. 1) or 24 (FIG. 2) of the holding means on the opposite side. The final angle in the stretching direction of the film is determined by the stroke difference Ay-Ax (that is, | L1-L2) of the left and right holding means at the end point (substantially holding release point) of the substantial stretching step.
|) And the distance W between the substantial holding release points (distance between Cx and Ay)
And the ratio. Therefore, the inclination angle θ formed by the stretching direction with respect to the conveying direction to the next step is tan θ = W / (Ay−Ax), that is, an angle satisfying tan θ = W / | L1-L2 |. The upper film edge in FIGS. 1 and 2 is held up to 18 (FIG. 1) or 28 (FIG. 2) even after the Ay point, but no new widthwise stretching occurs because the other end is not held. No. 18 and 28 are not the substantial release points of the present invention.

As described above, in the present invention, the substantial holding start points at both ends of the film are not the simple points of biting into the left and right holding means. The two substantial holding start points of the present invention are, if the above definition is described more strictly, a film in which a straight line connecting either the left or right holding point and the other holding point is introduced in the step of holding the film. Is substantially orthogonal to the centerline of the, and these two holding points are defined as the most upstream positions. Similarly,
In the present invention, the two substantial holding release points, a straight line connecting either the left or right holding point and the other holding point is a point substantially orthogonal to the center line of the film sent to the next step,
Moreover, these two holding points are defined as being located at the most downstream. Here, “substantially orthogonal” means that the straight line connecting the center line of the film and the left and right substantial holding start points or substantial holding release points is 90 ± 0.5 °.

When an attempt is made to make a left and right stroke difference as in the present invention by using a tenter type stretching machine, the biting point into the holding means and the actual holding start point are often set due to mechanical restrictions such as rail length. Although a large deviation may occur or a large deviation may occur between the detachment point from the holding means and the substantial holding release point, the process between the substantial holding start point and the substantial holding release point defined above has the relationship of equation (1). If it satisfies, diagonal stretching is achieved.

The tilt angle of the orientation axis in the obtained stretched film can be controlled and adjusted by the ratio of the exit width W in the step (c) and the stroke difference | L1-L2 | between the two left and right holding means. it can. In order to obtain an orientation angle close to 45 ° in order to achieve the object of the present invention, it is preferable that the following formula (2) is satisfied, and the formula (2) 0.9W <| L1-L2 | <1.1W is more preferable. Preferably satisfies the following formula (3). Formula (3) 0.97W <| L1-L2 | <1.03W

The specific structure of the drawing process can be arbitrarily designed in consideration of equipment cost and productivity as long as the formula (1) is satisfied.

The film introduction direction (a) to the stretching step,
The angle formed by the film transport direction (b) to the next step can be any value, but from the viewpoint of minimizing the total installation area of equipment including the steps before and after stretching, this angle should be smaller. It is preferably within 3 °, more preferably within 0.5 °.

From the viewpoint of minimizing the equipment cost of the stretching process, the smaller the number of bends and the bending angle of the locus of the holding means, the better.

In the present invention, a tenter type apparatus is preferable as an apparatus for applying tension while stretching the film while holding both ends. In addition to the conventional two-dimensional tenter, it is possible to use a stretching process in which the gripping means at both ends are spirally provided with a path difference.

If there is a difference in the traveling speed of the film at the exit of the stretching process, wrinkles or deviations occur at the exit of the stretching process. Therefore, the difference in transport speed between the left and right film gripping means is substantially the same. Desired. The speed difference is preferably 1% or less, more preferably less than 0.5%, most preferably less than 0.05%. The speed described here is the length of the trajectory of the left and right holding means per minute. In a typical tenter stretching machine, etc., there are speed irregularities that occur on the order of seconds or less depending on the cycle of the sprocket teeth that drive the chain, the frequency of the drive motor, etc. It does not correspond to the speed difference described in the invention.

The preferred draw ratio is 1.1 times or more and 3.0 times or less, more preferably 1.15 times or more and 2.3 times or less, and further preferably 1.2 times or more and 2.0 times or less. The time required for stretching is preferably 1 second or more and 2 minutes or less, and 1 second or more 90
Within seconds is more preferable.

The thickness of the film of the present invention before stretching is 40 μm.
m or more and 200 μm or less is preferable, more preferably 45 μm
m or more and 180 μm or less, more preferably 40 μm or more 1
It is 50 μm or less. The preferred film width before stretching is 5
cm or more and 3 m or less, more preferably 8 cm or more and 2.5 m or less, and further preferably 10 cm or more and 2 m or less.

A step (moisture control step) for allowing water to be contained can be provided immediately before the film introduction port in the stretching step. As the water-containing method in the humidity control step, the film may be immersed in a water tank, or the entire step may be kept at high humidity and the film may be conveyed.

A drying process is provided after the exit of the stretching process.
The transport method in the drying step is not particularly limited, and roll transport is preferable, for example. The drying temperature is preferably 80 ° C to 140 ° C, more preferably 100 ° C to 140 ° C, most preferably 100 ° C to 130 ° C. The conveying speed is not particularly limited, but 0.1 to 100 m / min is preferable.

[Cellulose Acetate Film] The cellulose acetate film of the present invention has an acetylation degree of 5.
It is preferred to use cellulose acetate which is between 7.0% and 62.5%. In particular, the acetylation degree is preferably 58.0% to 62.0%. The degree of acetylation means the amount of bound acetic acid per unit mass of cellulose. The acetylation degree follows the measurement and calculation of the acetylation degree in ASTM: D-817-91 (test method for cellulose acetate etc.).

Viscosity average degree of polymerization of cellulose ester (D
P) is preferably 250 or more, more preferably 290 or more. The cellulose acetate used in the present invention preferably has a narrow molecular weight distribution of Mw / Mn (Mw is a mass average molecular weight and Mn is a number average molecular weight) by gel permeation chromatography. The specific value of Mw / Mn is preferably 1.0 to 1.7, more preferably 1.3 to 1.65, and most preferably 1.4 to 1.6. preferable. It is preferable to use a cellulose acetate film having a light transmittance of 80% or more.

[Film Retardation] The retardation value (Re) is calculated according to the following formula. Retardation value (Re) = (nx−ny) × d where nx is the in-plane refractive index in the slow axis direction (maximum in-plane refractive index) of the optical compensation film; ny is the optical compensation Is the refractive index in the plane perpendicular to the slow axis of the film;
Then, d is the thickness (nm) of the optical compensation film.

Λ consisting of the cellulose acetate of the present invention
The / 4 plate has a retardation value (Re450) measured at a wavelength of 450 nm of 60 to 135 nm and a retardation value (Re59) measured at a wavelength of 590 nm.
0) is 100 to 170 nm, and 2 nm ≦ Re5
Satisfies the relationship of 90-Re450 ≦ 100 nm. 5nm ≦ Re590-Re450
More preferably ≦ 80 nm, 10 nm ≦ Re590-Re45
Most preferably, 0 ≦ 50 nm.

[NZ Factor] A single cellulose acetate film used in the present invention can satisfy the following formula. 1 ≦ (nx-nz) / (nx-ny) ≦ 3 where nx is the refractive index in the in-plane slow axis direction of the optical compensation film; ny is the in-plane retardation of the optical compensation film Is the refractive index in the direction perpendicular to the axis; and nz is the refractive index in the thickness direction. It is preferably 1.1 or more and 2.8 or less, more preferably 1.2 or more and 2.7 or less, and particularly when 1.5 or more and 2.5 or less, the method of the present invention is effective.

The cellulose acetate film having the above-mentioned optical properties can be manufactured by the materials described below.

[Retardation Control Agent] In order to adjust the retardation value at each wavelength, it is preferable to add a retardation control agent to cellulose acetate. The retardation control agent is preferably used in the range of 0.01 to 30 parts by mass, more preferably 0.05 to 25 parts by mass, and more preferably 0. More preferably, it is used in the range of 1 to 20 parts by mass. You may use together two or more types of retardation control agents.

The retardation controlling agent is 210 to 3
It preferably has a maximum absorption wavelength in the wavelength region of 60 nm. The retardation control agent preferably has substantially no absorption in the visible region. As the retardation controlling agent, it is preferable to use a compound having at least two “aromatic rings”. This "aromatic ring"
Includes an aromatic heterocycle 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, preferably a 5-membered ring, a 6-membered ring or a 7-membered ring, more preferably a 5-membered ring or a 6-membered ring. The aromatic heterocycle generally has the largest number of 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 the aromatic hetero ring are a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, an imidazole ring, a pyrazole ring, a furazan ring, a triazole ring, a pyran ring and a pyridine ring. , A pyridazine ring, a pyrimidine ring, a pyrazine ring and a 1,3,5-triazine ring.

Specific examples of the aromatic ring include benzene ring, furan ring, thiophene ring, pyrrole ring, oxazole ring,
Thiazole ring, imidazole ring, triazole ring, pyridine ring, pyrimidine ring, pyrazine ring and 1,3,5-
A triazine ring is preferred. The number of these aromatic rings is 2
It is preferably from 20 to 20, more preferably from 2 to 12, and most preferably from 2 to 6.
As such a retardation control agent, any of the following (a) plate-like compound and (b) rod-like compound may be used. These may be used alone or in combination.

(A) Plate-like compound This compound contains two pairs of aromatic rings. The bonding relationship between these two aromatic rings is such that when (a) a condensed ring is formed, (b) a single ring is formed. It can be classified into a case where it is directly connected by a bond and a case where it is connected through a linking group (c) (a spiro bond cannot be formed due to an aromatic ring), but the bonding relationship may be any of (a) to (c).

Examples of the condensed ring of (a) (condensed ring of two or more aromatic rings) include indene ring, naphthalene ring, azulene ring, fluorene ring, phenanthrene ring, anthracene ring, acenaphthylene ring, biphenylene ring, Naphthacene ring, pyrene ring, indole ring, isoindole ring, benzofuran ring, benzothiophene ring, indolizine ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, purine ring, indazole ring, chromene ring, quinoline Ring, isoquinoline ring,
Quinolidine ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, carbazole ring, acridine ring, phenanthridine ring, xanthene ring, phenazine ring, phenothiazine ring, phenoxathiin ring, phenoxazine ring and thianthrene ring included. A naphthalene ring, an azulene ring, an indole ring, a benzoxazole ring, a benzothiazole ring, a benzimidazole ring, a benzotriazole ring and a quinoline ring are preferable.

The single bond (b) is preferably a bond between carbon atoms of two aromatic rings. Two or more single bonds may combine two aromatic rings to form an aliphatic ring or a non-aromatic heterocycle between the two aromatic rings. (C)
The linking group of is also preferably bonded to carbon atoms of two aromatic rings. The linking group is preferably an alkylene group, an alkenylene group, an alkynylene group, -CO-, -O-, -NH-, -S- or a combination thereof. Examples of linking groups composed of combinations are shown below. Note that the left-right relationship in the following examples of the linking group may be reversed.

C1: -CO-O- c2: -CO-NH- c3: -alkylene-O- c4: -NH-CO-NH- c5: -NH-CO-O- c6: -O-CO-O -c7: -O-alkylene-O- c8: -CO-alkenylene-c9: -CO-alkenylene-NH- c10: -CO-alkenylene-O- c11: -alkylene-CO-O-alkylene-O-CO- Alkylene-c12: -O-alkylene-CO-O-alkylene-O-CO-alkylene-O- c13: -O-CO-alkylene-CO-O- c14: -NH-CO-alkenylene-c15: -O- CO-alkenylene-

The aromatic ring and the linking group may have a substituent. Examples of the substituent include a halogen atom (F, C
1, Br, I), hydroxyl, carboxyl, cyano, amino, nitro, sulfo, carbamoyl, sulfamoyl, ureido, alkyl group, alkenyl group, alkynyl group, aliphatic acyl group, aliphatic acyloxy group, alkoxy group, alkoxycarbonyl group , Alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamide group, aliphatic substituted amino group, aliphatic substituted carbamoyl group, aliphatic substituted sulfamoyl group, aliphatic substituted ureido group and non-aromatic An aromatic heterocyclic group is included.

The number of carbon atoms in the alkyl group is preferably 1-8. A chain alkyl group is preferable to a cyclic alkyl group, and a straight chain alkyl group is particularly preferable.
The alkyl group may further have a substituent (eg, hydroxy, carboxy, alkoxy group, alkyl-substituted amino group). Examples of alkyl groups (including substituted alkyl groups) include methyl, ethyl, n-butyl, n-hexyl, 2-
Included are hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl and 2-diethylaminoethyl. The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferable to a cyclic alkenyl group, and a straight chain alkenyl group is particularly preferable. The alkenyl group may further have a substituent. Examples of alkenyl groups include vinyl, allyl and 1-hexenyl. The alkynyl group preferably has 2 to 8 carbon atoms. A chain alkynyl group is preferable to a cyclic alkynyl group, and a straight chain alkynyl group is particularly preferable. The alkynyl group may further have a substituent. Examples of alkynyl groups include ethynyl, 1-butynyl and 1-hexynyl.

The number of carbon atoms of the aliphatic acyl group is 1 to 1
It is preferably 0. Examples of the aliphatic acyl group include acetyl, propanoyl and butanoyl. The number of carbon atoms of the aliphatic acyloxy group is preferably 1-10. Examples of the aliphatic acyloxy group include acetoxy. The number of carbon atoms of the alkoxy group is preferably 1-8. The alkoxy group may further have a substituent (eg, an alkoxy group). Examples of alkoxy groups (including substituted alkoxy groups) include methoxy, ethoxy, butoxy and methoxyethoxy. The alkoxycarbonyl group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonyl group include methoxycarbonyl and ethoxycarbonyl. The alkoxycarbonylamino group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonylamino group include methoxycarbonylamino and ethoxycarbonylamino.

The number of carbon atoms of the alkylthio group is 1 to 1.
It is preferably 2. Examples of the alkylthio group include methylthio, ethylthio and octylthio.
The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of alkylsulfonyl groups include methanesulfonyl and ethanesulfonyl. The number of carbon atoms in the aliphatic amide group is preferably 1-10. Examples of the aliphatic amide group include acetamide. The aliphatic sulfonamide group preferably has 1 to 8 carbon atoms. Examples of the aliphatic sulfonamide group include methanesulfonamide, butanesulfonamide and n-octanesulfonamide.

The number of carbon atoms of the aliphatic substituted amino group is preferably 1-10. Examples of the aliphatic-substituted amino group include dimethylamino, diethylamino and 2-carboxyethylamino. The number of carbon atoms of the aliphatic-substituted carbamoyl group is preferably 2-10. Examples of the aliphatic substituted carbamoyl group include methylcarbamoyl and diethylcarbamoyl. The number of carbon atoms of the aliphatic-substituted sulfamoyl group is preferably 1-8. Examples of the aliphatic substituted sulfamoyl group include methylsulfamoyl and diethylsulfamoyl. The number of carbon atoms of the aliphatic substituted ureido group is
It is preferably 2 to 10. Examples of the aliphatic substituted ureido group include methylureido. Examples of the non-aromatic heterocyclic group include piperidino and morpholino. The retardation control agent has a molecular weight of 300 to 8
It is preferably 00. Specific examples of such a plate-like retardation control agent are shown in International Patent Application Publication WO00 /
No. 65384, etc.

(B) Rod-shaped compound In the present invention, it is also preferable to use a rod-shaped compound having an absorption maximum on the shorter wavelength side than 250 nm as a retardation control agent. From the viewpoint of the function of the retardation control agent, the rod-shaped compound preferably has at least one aromatic ring, and more preferably has at least two aromatic rings.

The rod-shaped compound preferably has a linear molecular structure. The linear molecular structure means that the rod-shaped compound has a linear molecular structure in the most thermodynamically stable structure. The thermodynamically most stable structure can be obtained by crystal structure analysis or molecular orbital calculation. For example, molecular orbital calculation software (eg WinMOPAC200
0, manufactured by Fujitsu Ltd., can be used to calculate the molecular orbital to obtain the molecular structure that minimizes the heat of formation of the compound. The linear molecular structure means that the angle of the molecular structure is 140 degrees or more in the thermodynamically most stable structure calculated as described above.

As the rod-shaped compound, a compound represented by the following formula (I) is preferable. (I) Ar ¹ -L ¹ -Ar ^{2 In the} formula (I), Ar ¹ and Ar ² are each independently an aromatic group. In the present specification, the aromatic group includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocyclic group and a substituted aromatic heterocyclic group. The aryl group and the substituted aryl group are more preferable than the aromatic heterocyclic group and the substituted aromatic heterocyclic group. The heterocycle of the aromatic heterocyclic group is generally unsaturated. The aromatic heterocycle is preferably a 5-membered ring, a 6-membered ring or a 7-membered ring, more preferably a 5-membered ring or a 6-membered ring. The aromatic heterocycle generally has the largest number of double bonds. The hetero atom is preferably a nitrogen atom, an oxygen atom or a sulfur atom, more preferably a nitrogen atom or a sulfur atom. Examples of the aromatic hetero ring are a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, an imidazole ring, a pyrazole ring, a furazan ring,
It includes a triazole ring, a pyran ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, and a 1,3,5-triazine ring. As the aromatic ring of the aromatic group,
A benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring are preferable, and a benzene ring is particularly preferable.

Examples of the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include a halogen atom (F, Cl, B
r, I), hydroxyl, carboxyl, cyano, amino, alkylamino group (eg, methylamino, ethylamino, butylamino, dimethylamino), nitro, sulfo, carbamoyl, alkylcarbamoyl group (eg, N-
Methylcarbamoyl, N-ethylcarbamoyl, N, N-
Dimethylcarbamoyl), sulfamoyl, alkylsulfamoyl group (eg, N-methylsulfamoyl, N-ethylsulfamoyl, N, N-dimethylsulfamoyl), ureido, alkylureido group (eg, N-methylureido) , N, N-dimethylureido, N, N, N′-trimethylureido), alkyl groups (eg, methyl, ethyl, propyl, butyl, pentyl, heptyl, octyl, isopropyl, s-butyl, t-amyl, cyclohexyl, Cyclopentyl), alkenyl groups (eg vinyl,
Allyl, hexenyl), alkynyl groups (eg, ethynyl,
Butynyl), acyl group (eg, formyl, acetyl, butyryl, hexanoyl, lauryl), acyloxy group (eg, acetoxy, butyryloxy, hexanoyloxy, lauryloxy), alkoxy group (eg, methoxy,
Ethoxy, propoxy, butoxy, pentyloxy, heptyloxy, octyloxy), aryloxy group (eg, phenoxy), alkoxycarbonyl group (eg, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentyloxycarbonyl, heptyloxycarbonyl) ), An aryloxycarbonyl group (eg, phenoxycarbonyl), an alkoxycarbonylamino group (eg, butoxycarbonylamino,
Hexyloxycarbonylamino), an alkylthio group (eg, methylthio, ethylthio, propylthio, butylthio, pentylthio, heptylthio, octylthio),
Arylthio group (eg, phenylthio), alkylsulfonyl group (eg, methylsulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl, pentylsulfonyl, heptylsulfonyl, octylsulfonyl), amide group (eg, acetamide, butylamide group, hexylamide, lauryl) Amide) and non-aromatic heterocyclic groups (eg morpholyl, pyrazinyl).

Examples of the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include a halogen atom, cyano, carboxyl, hydroxyl, amino, an alkyl-substituted amino group, an acyl group, an acyloxy group, an amide group, an alkoxycarbonyl group and an alkoxy group. Groups, alkylthio groups and alkyl groups are preferred. The alkyl moiety of the alkylamino group, the alkoxycarbonyl group, the alkoxy group and the alkylthio group and the alkyl group may further have a substituent. Examples of alkyl moieties and substituents on alkyl groups include halogen atoms, hydroxyl, carboxyl, cyano, amino, alkylamino groups, nitro, sulfo, carbamoyl, alkylcarbamoyl groups, sulfamoyl,
Alkylsulfamoyl group, ureido, alkylureido group, alkenyl group, alkynyl group, acyl group, acyloxy group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, alkoxycarbonylamino group, alkylthio group, arylthio group , Alkylsulfonyl groups, amide groups and non-aromatic heterocyclic groups. As the alkyl moiety and the substituent of the alkyl group, a halogen atom, hydroxyl, amino, an alkylamino group, an acyl group, an acyloxy group, an acylamino group, an alkoxycarbonyl group and an alkoxy group are preferable.

In the formula (I), L ¹ is a divalent linking group selected from the group consisting of an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO— and combinations thereof. The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a straight chain alkylene group is preferable to a branched alkylene group. The alkylene group has preferably 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, and 1 to 10 carbon atoms.
Is more preferred, 1 to 8 is still more preferred, and 1 to 6 is most preferred.

The alkenylene group and alkynylene group are
A chain structure is preferable to a cyclic structure, and a straight chain structure is more preferable to a branched chain structure. The alkenylene group and the alkynylene group each have preferably 2 to 10 carbon atoms, more preferably 2 to 8 carbon atoms, further preferably 2 to 6 carbon atoms, and further preferably 2 to 4 carbon atoms. Most preferably, it is 2 (vinylene or ethynylene).

An example of a divalent linking group composed of a combination will be shown. L-1: -O-CO-alkylene group-CO-O-L-2: -CO-O-alkylene group-O-CO-L-3: -O-CO-alkenylene group-CO-O-L- 4: -CO-O-alkenylene group-O-CO-L-5: -O-CO-alkynylene group-CO-O-L-6: -CO-O-alkynylene group-O-CO-

In the molecular structure of formula (I), the angle formed by Ar ¹ and Ar ² with L ¹ sandwiched therebetween is preferably 140 ° or more. As the rod-shaped compound, a compound represented by the following formula (II) is more preferable. (II) Ar ¹ -L ² -X-L ³ -Ar ^{2 In the} formula (II), Ar ¹ and Ar ² are each independently an aromatic group. The definition and examples of the aromatic group are the same as Ar ¹ and Ar ² of the formula (I).

In the formula (II), L ² and L ³ are each independently a divalent linking group selected from the group consisting of alkylene groups, —O—, —CO— and combinations thereof. The alkylene group preferably has a chain structure rather than a cyclic structure, and more preferably has a straight chain structure rather than a branched chain structure. The number of carbon atoms of the alkylene group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, still more preferably 1 to 4 and 1 or Most preferably it is 2 (methylene or ethylene). L ² and L ³ are -O-CO- or-
Particularly preferred is CO-O-.

In the formula (II), X is 1,4-cyclohexylene, vinylene or ethynylene. Specific examples of the compound represented by formula (I) are shown below.

[0064]

[Chemical 1]

[0065]

[Chemical 2]

[0066]

[Chemical 3]

[0067]

[Chemical 4]

[0068]

[Chemical 5]

[0069]

[Chemical 6]

[0070]

[Chemical 7]

[0071]

[Chemical 8]

[0072]

[Chemical 9]

Specific examples (1) to (34), (41),
(42) has two asymmetric carbon atoms at the 1-position and 4-position of the cyclohexane ring. However, specific examples (1) and (4)
Since (34), (41), and (42) have a symmetrical meso-type molecular structure, they have no optical isomer (optical activity),
There are only geometric isomers (trans and cis). Specific example (1) trans type (1-trans) and cis type (1-cis)
And are shown below.

[0074]

[Chemical 10]

As described above, the rod-shaped compound preferably has a linear molecular structure. Therefore, the trans type is preferable to the cis type. The specific examples (2) and (3) have optical isomers (total of 4 isomers) in addition to geometrical isomers. Regarding geometrical isomers, the trans form is also preferable to the cis form. The optical isomer is not particularly superior or inferior and may be any of D, L and racemates. In specific examples (43) to (45), the central vinylene bond has a trans type and a cis type. For the same reason as above, the trans type is preferable to the cis type.

Two or more rod-like compounds having a maximum absorption wavelength (λmax) shorter than 250 nm in the ultraviolet absorption spectrum of the solution may be used in combination. The rod-shaped compound is
It can be synthesized by referring to the method described in the literature. As literature,
Mol. Cryst. Liq. Cryst., 53, 229 (1979)
), 89, 93 (1982), 145, 111
Page (1987), Volume 170, Page 43 (1989)
Year), J. Am. Chem. Soc., 113, 1349 pages (199
1 year), vol. 118, p. 5346 (1996), id. 92
Volume, 1582 (1970), J. Org. Chem., 40.
Volume, 420 pages (1975), Tetrahedron, Volume 48 16
Issue, page 3437 (1992).

The retardation control agent of the present invention may be used alone or as a mixture of two or more compounds.

[Production of Cellulose Acetate Film]
It is preferable to produce the cellulose acetate film by the solvent casting method. In the solvent cast method, a film is manufactured using a solution (dope) in which a polymer material is dissolved in an organic solvent. The production of the cellulose acetate film of the present invention will be specifically described by taking cellulose acetate as an example. The organic solvent is an ether having 3 to 12 carbon atoms, a ketone having 3 to 12 carbon atoms,
It is preferable to include a solvent selected from an ester having 3 to 12 carbon atoms and a halogenated hydrocarbon having 1 to 6 carbon atoms. Ethers, ketones and esters are
It may have a ring structure. Functional groups of ethers, ketones and esters (ie -O-, -CO- and -C
A compound having two or more of any one of OO-) can also be used as the organic solvent. The organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone. 3 to 1 carbon atoms
Examples of the esters of 2 include ethyl formate, propyl formate, pentyl formate, methyl acetate,
Includes ethyl acetate and pentyl acetate.

Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol. The number of carbon atoms in the halogenated hydrocarbon is preferably 1 or 2, and most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine. The proportion of hydrogen atoms in the halogenated hydrocarbon substituted with halogen is preferably 25 to 75 mol%, more preferably 30 to 70 mol%, and 3
It is more preferably 5 to 65 mol%, and most preferably 40 to 60 mol%. Methylene chloride is a typical halogenated hydrocarbon. You may mix and use 2 or more types of organic solvents.

The cellulose acetate solution can be prepared by a general method. The general method means treatment at a temperature of 0 ° C. or higher (normal temperature or high temperature). The solution can be prepared by using the dope preparation method and apparatus in the usual solvent casting method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly methylene chloride) as the organic solvent. The amount of cellulose acetate is adjusted so that the obtained solution contains 10 to 40% by mass. The amount of cellulose acetate is more preferably 10 to 30% by mass. The organic solvent (main solvent) may contain any of the additives described below. The solution can be prepared by stirring cellulose acetate and an organic solvent at room temperature (0 to 40 ° C.). The highly concentrated solution may be stirred under pressure and heat. Specifically, the cellulose acetate and the organic solvent are placed in a pressure vessel and sealed, and the mixture is stirred under pressure while being heated to a temperature not lower than the boiling point of the solvent at room temperature and not boiling the solvent. The heating temperature is usually 40 ° C. or higher, preferably 60 to 200 ° C., and more preferably 80 to 110 ° C.

Each component may be roughly mixed in advance and then put in a container. Moreover, you may throw in in a container one by one. The container must be configured to allow stirring. The container can be pressurized by injecting an inert gas such as nitrogen gas. Alternatively, the increase in vapor pressure of the solvent due to heating may be used.
Alternatively, after sealing the container, each component may be added under pressure.

When heating, it is preferable to heat from the outside of the container. For example, a jacket type heating device can be used. It is also possible to heat the entire container by providing a plate heater outside the container and piping to circulate the liquid. It is preferable to provide a stirring blade inside the container and use this to stir. The stirring blade is
The length that reaches the vicinity of the wall of the container is preferable. A scraping blade is preferably provided at the end of the stirring blade in order to renew the liquid film on the wall of the container. Instruments such as a pressure gauge and a thermometer may be installed in the container. Each component is dissolved in a solvent in a container. The prepared dope is cooled and then taken out from the container, or after taking out, it is cooled using a heat exchanger or the like.

The solution can also be prepared by the cooling dissolution method. In the cooling dissolution method, cellulose acetate can be dissolved even in an organic solvent which is difficult to dissolve by a usual dissolution method. It is common to use methylene chloride as the organic solvent for cellulose acetate. However, methylene chloride is harmful to the global environment and work environment, and therefore it is desired not to use it. In an organic solvent system that does not use methylene chloride, it is difficult to dissolve by an ordinary dissolution method, and in this case, the cooling dissolution method is effective. Even if the solvent is a solvent that can dissolve cellulose acetate by an ordinary dissolution method, the cooling dissolution method has an effect of rapidly obtaining a uniform solution. In the cooling dissolution method, first, cellulose acetate is gradually added to an organic solvent with stirring at room temperature. The amount of cellulose acetate is preferably adjusted so as to be contained in this mixture in an amount of 10 to 40% by mass. The amount of cellulose acetate is more preferably 10 to 30% by mass. Furthermore, any additives described below may be added to the mixture.

Next, the mixture is heated to -100 to -10 ° C (preferably -80 to -10 ° C, more preferably -50 to-).
20 ° C, most preferably -50 to -30 ° C). For cooling, for example, dry ice / methanol bath (-
75 ℃ or cooled diethylene glycol solution (-30
To -20 ° C). When cooled in this way, the mixture of cellulose acetate and organic solvent solidifies. The cooling rate is preferably 4 ° C./min or more,
It is more preferably 8 ° C./min or higher, and most preferably 12 ° C./min or higher. The faster the cooling rate, the more preferable, but 10,000 ° C./sec is the theoretical upper limit,
1000 ° C / sec is the technical upper limit, and 100 ° C
/ Sec is a practical upper limit. The cooling rate is a value obtained by dividing the difference between the temperature at the start of cooling and the final cooling temperature by the time from the start of cooling until the final cooling temperature is reached.

Further, this is applied at 0 to 200 ° C. (preferably 0 to 150 ° C., more preferably 0 to 120 ° C.,
When heated to the most preferably 0 to 50 ° C., the cellulose acetate dissolves in the organic solvent. The temperature may be raised by leaving it at room temperature or by heating it in a warm bath. The heating rate is preferably 4 ° C / min or more, and 8 ° C / min.
It is more preferably at least minutes, and most preferably at 12 ° C./minute or more. The higher the heating rate, the more preferable, but 10000 ° C./sec is the theoretical upper limit,
0 ° C./sec is the technical upper limit and 100 ° C./sec is the practical upper limit. The heating rate is a value obtained by dividing the difference between the temperature at the start of heating and the final heating temperature by the time from the start of heating until the final heating temperature is reached. . A uniform solution is obtained as described above. If the dissolution is insufficient, the cooling and heating operations may be repeated. Whether or not the dissolution is sufficient can be judged only by visually observing the appearance of the solution.

In the cooling dissolution method, it is desirable to use a closed container in order to avoid mixing of water due to dew condensation during cooling. In the cooling and heating operation, pressure is applied during cooling,
If the pressure is reduced during heating, the dissolution time can be shortened. In order to carry out the pressurization and depressurization, it is desirable to use a pressure resistant container.

Cellulose acetate (degree of acetylation: 6
A solution of 20% by mass in which 0.9% and a viscosity average degree of polymerization: 299) was dissolved in methyl acetate by a cooling dissolution method is
According to differential scanning calorimetry (DSC), a pseudo phase transition point between a sol state and a gel state exists near 33 ° C., and at this temperature or lower, a uniform gel state is obtained. Therefore, this solution has a pseudo-phase transition temperature or higher, preferably a gel phase transition temperature plus 1
It is necessary to keep the temperature at about 0 ° C. However, this pseudo-phase transition temperature differs depending on the degree of acetylation of cellulose acetate, the viscosity average degree of polymerization, the solution concentration and the organic solvent used.

A cellulose acetate film is produced from the prepared cellulose acetate solution (dope) by the solvent casting method. The dope is cast on a drum or band and the solvent is evaporated to form a film. The dope before casting has a solid content of 18 to 35% by mass.
It is preferable to adjust the concentration so that The surface of the drum or band is preferably mirror-finished. Regarding the casting and drying methods in the solvent casting method, US Pat.
No. 7603, No. 2492078, No. 2492977
No. 2,492,978, No. 2,607,704, No. 27.
No. 39069, No. 2739070, British Patent 6407
No. 31, 736892, each specification, Japanese Examined Patent Publication No. 45-4
554, 49-5614, and JP-A-60-1768.
34, 60-203430, 62-11503.
It is described in each publication of No. 5.

The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or lower. After casting, it is preferable to apply air for 2 seconds or more to dry. It is also possible to strip the obtained film from the drum or band and further dry it with hot air whose temperature is successively changed from 100 to 160 ° C. to evaporate the residual solvent. The above method is described in Japanese Patent Publication No. 5-17844. According to this method, the time from casting to stripping can be shortened. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or band during casting.

Further, a cellulose acetate film may be produced by a solvent casting method in order to form a film by casting one or more layers using the prepared cellulose acetate solution (dope). The dope is cast on a drum or band and the solvent is evaporated to form a film. The dope before casting is preferably adjusted in concentration so that the solid content is 10-40%. The surface of the drum or band is preferably mirror-finished.

When a plurality of cellulose acetate solutions having two or more layers are cast, a solution containing cellulose acetate is cast from a plurality of casting ports provided at intervals in the traveling direction of the support. The film may be produced by laminating the films, and the methods described in, for example, JP-A-61-158414, JP-A-1-122419, and JP-A-11-198285 can be applied. The cellulose acetate solution may be cast from two casting ports to form a film, for example, Japanese Patent Publication No. 60-27562 and JP-A No. 61-9.
4724, JP-A-61-942245, JP-A-61
It can be carried out by the method described in JP-A-104813, JP-A-61-158413 and JP-A-6-134933. Also, a cellulose acetate film casting method described in JP-A-56-162617 may be used in which the flow of a high-viscosity cellulose acetate solution is wrapped with a low-viscosity cellulose acetate solution and the high- and low-viscosity cellulose acetate solutions are simultaneously extruded. .

Alternatively, by using two casting ports, the film cast on the support is peeled off by the first casting port, and the second casting is performed on the side in contact with the surface of the support. It is also possible to prepare a film, for example, Japanese Patent Publication No.
4-20235. The cellulose acetate solution to be cast may be the same solution,
Different cellulose acetate solutions may be used and are not particularly limited. In order to give a function to a plurality of cellulose acetate layers, a cellulose acetate solution corresponding to the function may be extruded from each casting port. Further, this cellulose acetate solution is used for other functional layers (eg, adhesive layer, dye layer, antistatic layer, antihalation layer, UV layer).
It is also possible to cast the absorbing layer, the polarizing layer, etc.) simultaneously.

In the monolayer solution, it is necessary to extrude a high-concentration and high-viscosity cellulose acetate solution in order to obtain a required film thickness. In that case, the stability of the cellulose acetate solution is poor and solid matters are not formed. It often occurs and causes a problem such as a bump failure or poor flatness. As a solution to this problem, by casting a plurality of cellulose acetate solutions through a casting port, a highly viscous solution can be simultaneously extruded onto a support, and flatness can be improved to produce an excellent planar film. Not only that, by using a concentrated cellulose acetate solution, it is possible to reduce the drying load and increase the film production speed.

A plasticizer may be added to the cellulose acetate film in order to improve the mechanical properties or the drying speed. As a plasticizer,
Phosphate esters or carboxylic acid esters are used. Examples of the phosphoric acid ester include triphenyl phosphate (TPP) and biphenyl diphenyl phosphate (BDP), tricresyl phosphate (TCP). Typical carboxylic acid esters are phthalic acid esters and citric acid esters. Examples of phthalates include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DB
P), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethylhexyl phthalate (DEHP). Examples of citrate esters include:
Includes O-acetyl triethyl citrate (OACTE) and O-acetyl tributyl citrate (OACTB). Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phthalates plasticizer (DMP, DEP, DBP, D
OP, DPP, DEHP) are preferably used. DE
P and DPP are particularly preferred. The addition amount of the plasticizer is preferably 0.1 to 25% by mass of the amount of cellulose ester, more preferably 1 to 20% by mass, and most preferably 3 to 15% by mass.

A deterioration inhibitor (eg, antioxidant, peroxide decomposer, radical inhibitor, metal deactivator, acid scavenger, amine) may be added to the cellulose acetate film. For the deterioration preventing agent, see JP-A-3-19920.
No. 1, No. 5-1907073, No. 5-194789
Nos. 5,271,471 and 6,107,854. The addition amount of the deterioration inhibitor is preferably 0.01 to 1% by mass of the solution (dope) to be prepared, and more preferably 0.01 to 0.2% by mass. If the addition amount is less than 0.01% by mass, the effect of the deterioration inhibitor is hardly recognized. Addition amount is 1% by mass
If it exceeds the range, bleed-out (bleeding) of the deterioration preventive agent on the film surface may be observed. Butylated hydroxytoluene (BHT) and tribenzylamine (TBA) can be mentioned as examples of particularly preferable deterioration preventing agents.

The cellulose acetate film may be provided with a mat layer containing a matting agent and a polymer on one side or both sides in order to improve the handling property during production.
For the matting agent and the polymer, see JP-A-10-443.
The materials described in No. 27 can be preferably used. The matting agent may be used as a mixture with the dope.

If necessary, various additives may be added to the cellulose acetate solution at any stage before the solution is prepared and after the solution is prepared. As additives, ultraviolet absorbers, silica, kaolin, talc, diatomaceous earth,
Examples thereof include inorganic fine particles such as quartz, calcium carbonate, barium sulfate, titanium oxide, and alumina, heat stabilizers such as salts of alkaline earth metals such as calcium and magnesium, antistatic agents, flame retardants, lubricants, and oil agents.

Further, a peeling accelerator may be added to reduce the load during peeling. Surfactants are effective for them, and phosphoric acid type, sulfonic acid type, carboxylic acid type,
There is no particular limitation such as nonionic or cationic. These are described, for example, in JP-A-61-243837.

[Surface Treatment of Retardation Plate] The retardation plate may be subjected to a surface treatment in order to maintain the adhesion to the polarizing plate. As a specific method, corona discharge treatment, glow discharge treatment, flame treatment, acid treatment, alkali treatment or ultraviolet irradiation treatment is carried out. From the viewpoint of maintaining the flatness of the film, the temperature of the cellulose acetate film is preferably Tg or lower in these treatments.

Particularly when used as a transparent protective film of a polarizing plate, it is particularly preferable to carry out acid treatment or alkali treatment, and more preferably alkali treatment, from the viewpoint of adhesiveness to the polarizing film. The alkali treatment is preferably carried out by a cycle of immersing the film surface in an alkali solution, neutralizing it with an acid solution, washing with water and drying.

Examples of the alkaline solution include potassium hydroxide solution and sodium hydroxide solution, and the normal concentration of hydroxide ion is preferably 0.1N to 3.0N, and 0.5N to 2.0N. Is more preferable. The temperature of the alkaline solution is preferably room temperature to 90 ° C, more preferably 40 ° C to 70 ° C. These alkaline solutions may be aqueous solutions or organic solvents. In the case of an organic solvent, a lower alcohol is preferred, more preferably an alcohol or glycol having 1 to 5 carbon atoms, more preferably ethanol, n-propanol, is.
o-Propanol, butanol, ethylene glycol, propylene glycol. More preferred are iso-propanol and propylene glycol. These may be mixed and used. Further, water or a surfactant may be added. Preferred examples include the following solutions in which alkali is dissolved. iso-propanol / propylene glycol / water (70/15/1
5: Volume ratio) iso-Propanol / water (85/15: Volume ratio) iso-Propanol / Propylene glycol (85/15: Volume ratio) iso-Propanol May be immersed in these alkaline solutions and applied (bar coating) , Curtain coating, etc.).

[Polarizing Plate] The polarizing plate comprises a polarizing film and two transparent protective films arranged on both sides of the polarizing film. The above-mentioned cellulose acetate film can be used as one protective film, or the long retardation plate of the present invention may be used. As the other protective film, an ordinary long cellulose acetate film may be used. The polarizing film includes an iodine-based polarizing film, a dye-based polarizing film using a dichroic dye, and a polyene-based polarizing film. The iodine type polarizing film and the dye type polarizing film are generally manufactured using a polyvinyl alcohol type film. The adhesive between the polarizing film and the protective layer is not particularly limited, but PVA-based resin (acetoacetyl group, sulfonic acid group,
(Including modified PVA such as a carboxyl group and an oxyalkylene group) and an aqueous solution of a boron compound, and the like. Among them, PV
A type resin is preferable. The thickness of the adhesive layer is 0.01 after drying.
To 10 μm is preferable, and 0.05 to 5 μm is particularly preferable. The relationship between the slow axis of the retardation plate and the absorption axis of the polarizing plate varies depending on the type of liquid crystal display device to be applied, but in the case of a reflective or semi-transmissive liquid crystal display device, it is arranged to be substantially 45 degrees Preferably.

The circularly polarizing plate of the present invention is a long circularly polarizing plate in which a long linear polarizing film and a long retardation plate of the present invention are laminated so that their longitudinal directions are parallel to each other. Is manufactured. A protective film may be further laminated on the side of the linear polarizing film opposite to the retardation plate.

[Image Display Device] The retardation plate and circularly polarizing plate of the present invention are advantageously used in a liquid crystal display device. The liquid crystal display device may be any of a transmissive type, a reflective type, and a semi-transmissive type, but the reflective type and the semi-transmissive type are particularly preferable. In that case, the liquid crystal display element is obtained by laminating the long circular polarizing plate of the present invention on a transparent substrate made of glass or plastic, and rolling the circular polarizing plate of the present invention on a mother glass cell filled with liquid crystal. It can be produced by laminating.

The liquid crystal cell is not particularly limited. Any liquid crystal display mode may be used, but in the reflective liquid crystal device, a TN (twisted nematic) type, a HAN (Hybrid) type are used.
Aligned Nematic) type, VA (Vertically Allignment)
Type or guest host display system is preferred. In the transflective liquid crystal display device, TN type, VA type, ECB type (Electric
aly Controlled Birefrigence) is preferably used.

The twist angle of the TN type liquid crystal cell is preferably 40 to 100 °, more preferably 50 to 90 °, and most preferably 60 to 80 °. The value (Δnd) of the refractive index anisotropy (Δn) of the liquid crystal layer and the thickness (d) of the liquid crystal layer is 0.1 to 0.5.
The thickness is preferably μm, more preferably 0.2 to 0.4 μm.

In the HAN type liquid crystal cell, it is preferable that the liquid crystal is substantially vertically aligned on one substrate and the pretilt angle on the other substrate is 0 to 45 °. The value (Δnd) of the refractive index anisotropy (Δn) of the liquid crystal layer and the thickness (d) of the liquid crystal layer is preferably 0.1 to 1.0 μm, and 0.3 to 0.8 μm. It is more preferable that there is. The substrate on the side of vertically aligning the liquid crystal may be the substrate on the reflection plate side or the substrate on the transparent electrode side.

In the VA type liquid crystal cell, rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied. The VA mode liquid crystal cell includes (1) a VA mode liquid crystal cell in a narrow sense in which rod-shaped liquid crystal molecules are aligned substantially vertically when no voltage is applied, and are aligned substantially horizontally when voltage is applied (Japanese Patent Laid-Open No. Hei 2-
176625 and Japanese Patent Publication No. 7-69536)
In addition to (2) the liquid crystal cell in which the VA mode is multi-domained is included in order to widen the viewing angle. Specifically, M
VA (SID97, Digest of tech. Papers (Proceedings)
28 (1997) 845, SID99, Digest of tec
h. Papers (Proceedings) 30 (1999) 206 and JP-A-11-258605), SURVAIVA
L (Monthly Display, Volume 6, Issue 3 (1999) 1
4), PVA (Asia Display98, Pro)
c.of the 18th Inter.Display res.Conf. (Proceedings) (1
998) 383), Para-A (LCD / PDP)
(Presented at International '99), DDVA
(SID98, Digest of tech. Papers (Proceedings) 29
(1998) 838), EOC (SID98, Dige
st of tech. Papers (Proceedings) 29 (1998) 319
), PSHA (SID98, Digest of tech.Paper
s (Proceedings) 29 (1998) 1081), RFF
MH (Asia Display98, Proc. Of the 18t
h Inter. Display res. Conf. (Proceedings) (1998) 3
75), HMD (SID98, Digest of tech. Pa
pers (Proceedings) 29 (1998) 702). In addition, (3) a mode (n-ASM mode) liquid crystal cell (IWD'98, Proc. Of the 5th Inter) in which rod-like liquid crystal molecules are substantially vertically aligned when no voltage is applied and twisted in a multi-domain alignment when a voltage is applied. .Display Wor
kshop. (Proceedings) (1998, 143))) is also included.

The ECB type liquid crystal cell is one which colors light by utilizing the birefringence effect of the liquid crystal layer and the polarization effect of the pair of polarizing plates without using a color filter. That is, the birefringence of the liquid crystal layer changes depending on the alignment state of the liquid crystal molecules depending on the voltage applied between the electrodes of both substrates of the liquid crystal cell, and the polarization state of each wavelength light incident on the other polarizing plate accordingly. Changes, the color of the colored light can be changed by controlling the voltage applied between the electrodes of the liquid crystal cell, and thus one pixel can display a plurality of colors.

A guest-host (GH) reflective liquid crystal cell is a so-called display type in which a dichroic dye mixed with a dichroic dye is used as a guest and a liquid crystal is used as a host, and a phase transition type (White-Taylor type) is used. ), A two-layer type and a λ / 4 type are known. The phase transition type is a system in which a chiral agent is added to a mixture of a liquid crystal and a dichroic dye, and switching is performed between a cholesteric phase and vertical alignment. This system can display black and white with one liquid crystal layer. However, there are problems that the contrast ratio is low, the driving voltage is high, and there is hysteresis, which makes gradation display difficult. The two-layer type is a system in which two layers of a mixture of liquid crystal and dichroic dye are provided. This method is characterized by a high contrast ratio. However, it is thick as a liquid crystal display element, and there is a problem that parallax occurs. Regarding the guest-host reflection type liquid crystal display device provided with a λ / 4 plate, JP-A-6-222350 and 6-222.
No. 351, No. 8-36174, No. 10-221688.
There is description in each bulletin of the issue

A circularly polarizing plate can be used for a touch panel or an organic EL display device. The touch panel is disclosed in Japanese Patent Laid-Open No. 5-
It can be applied to those described in No. 127822 and Japanese Patent Application No. 2000-236797. Further, organic EL display elements are disclosed in JP-A-11-305729 and 11-30.
No. 7250, those described in JP-A No. 2000-267097, and the like can be applied.

[0113]

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

(Measurement of Water Content) The water content was measured by the Karl Fischer method. Sample (0.9m × 4.5c
After removing the water droplets adhering to the surface, (2 m) was weighed, immediately put in a glass bottle with a polishing stopper, carried to a moisture meter, and measured within 3 minutes after sampling. The measurement was carried out using a vaporizer (VA-05 type manufactured by Mitsubishi Chemical) and a Karl Fischer moisture meter (CA-03 type manufactured by Mitsubishi Chemical), and the moisture in the sample was volatilized at 150 ° C and introduced into the moisture meter. It was measured. The water content was calculated by the water content (%) = 0.1 × (W / F), where W is the water content (μg) indicated by the water content meter and F (mg) is the weighed sample amount.

(Measurement of Retardation and NZ Factor) The retardation of the retardation plate is measured by an automatic birefringence meter (KOBR
A-21ADH / PR: Measured from the direction perpendicular to the sample film surface using Oji Scientific Instruments Co., Ltd. Of retarder
For the NZ factor, an automatic birefringence meter (KOBRA-21ADH / PR: manufactured by Oji Scientific Instruments) was used.
, The retardation was measured at a wavelength of 550 nm from a direction inclined by -40 degrees, and from the three Re values obtained, the refractive index nx in the slow axis direction and the refractive index ny in the direction perpendicular to the in-plane slow axis
And the refractive index nz in the thickness direction is calculated as (nx-nz) /
The value of (nx-ny) was calculated. The calculation was performed and averaged for each of the samples in the center and both ends in the width direction.

(Measurement of Haze) The haze of the obtained film was measured using a haze meter MODEL 1001DP (manufactured by Nippon Denshoku Industries Co., Ltd.). The measurement was performed for each of the samples in the center and both ends in the width direction and the results were averaged.

(Production of Cellulose Acetate Film 1) A cellulose acetate solution having the following composition was prepared.

[0118]

[Table 1]

[0119]

[Chemical 11]

The obtained dope was cast on a band for film formation and dried with a drying air at 80 ° C. The residual amount of solvent after drying was 30% by mass. The cellulose acetate film was peeled from the band, dried at 100 ° C. for 10 minutes, and then dried at 130 ° C. for 20 minutes to obtain a cellulose acetate film 1. The cellulose acetate film 1 had a width of 1340 mm and was wound into a roll. The residual solvent amount was 0.1% by mass, and the film thickness was 130 μm.

(Production of Cellulose Acetate Film 2) A cellulose acetate solution having the following composition was prepared.

[0122]

[Table 2]

The obtained dope was cast on a glass plate,
It was dried with a drying air of 80 ° C. The residual amount of solvent after drying is 3
It was 0 mass%. After peeling the cellulose acetate film from the glass and drying at 100 ° C. for 10 minutes,
It was dried at 0 ° C. for 30 minutes to obtain a cellulose acetate film 2. Cellulose acetate film 2 has a width of 108
It was wound into a roll at 0 mm. The residual solvent amount was 0.1% by mass, and the film thickness was 125 μm.

(Production of Cellulose Acetate Film 3): A cellulose acetate solution having the following composition was prepared.

[0125]

[Table 3]

Example 1 except that the obtained dope was used
A film was formed in the same manner as in 1. to obtain a cellulose acetate film 3 in a roll shape.

(Production of Cellulose Acetate Film 4) The 6-position acetyl group was substituted more than the 2-position and 3-position acetyl groups, and the 6-position, 2-position and 3-position acetylation degrees were 20. The same compounds as the materials used in the cellulose acetate film 1 were used except that 5%, 19.9% and 19.9% of cellulose acetate were used.

The dissolution method is as follows (cooling dissolution method). That is, the above compound was gradually added to the solvent with good stirring and allowed to swell at room temperature (25 ° C.) for 3 hours.
While slowly stirring the obtained swelling mixture, -8 ° C /
Cool to -30 ° C in minutes, then cool to -70 ° C 6
After a lapse of time, the temperature was raised at + 8 ° C./min, and the stirring of the content was started at the stage where the sol formation of the content had progressed to some extent. Fifty
The dope was obtained by heating to ℃.

The obtained dope was cast on a film forming band in the same manner as in Example 1 and dried at 85 ° C. The residual amount of solvent after drying was 25% by mass. The cellulose acetate film was peeled from the band, dried at 100 ° C. for 10 minutes, and then dried at 130 ° C. for 20 minutes to obtain a cellulose acetate film 4. The residual solvent amount was 0.3% by mass. The film thickness was 130 μm.

(Production of Retardation Plate 1) The long cellulose acetate film 1 obtained by film formation was slit at both ends so as to have a width of 920 mm, and attached to a stretching machine consisting of a water-containing step, a stretching step and a drying step. . In the water-containing step, the film was sent out into a stretching machine and immersed in a constant temperature water bath at 90 ° C. for 3 minutes. When a part of the sample was cut out and the water content was measured, it was 4.8% by mass. The hydrated cellulose acetate film was taken out of the water tank, and after removing water droplets with an air knife, it was sent to the stretching step shown in FIG. 2 in an atmosphere of 90 ° C., and stretched at 45 ° in the longitudinal direction. The draw ratio was 44.0%. After stretching, 12 in the drying process
It dried at 0 degreeC and obtained the phase difference plate. The water content was measured and found to be 1.5% by mass. The film thickness was 100 μm. Samples were cut out from the obtained retardation plate at the center and both ends in the width direction, the humidity was controlled for 2 hours in an atmosphere of 25 ° C. and 60% RH, and then the optical characteristics were measured. The results are shown in Table 4.

(Production of Retardation Plate 2) A long cellulose acetate film 1 obtained by film formation was slit at both ends to have a width of 920 mm, and sent out by a stretching machine consisting of a high humidity step, a stretching step and a drying step. Attached to the section. Temperature and humidity 8
The film was sent to a high humidity process set at 5 ° C. and 95% RH to absorb moisture for 5 minutes. A part of the sample was cut out and the water content was measured and found to be 4.6% by mass. The wet heat treated cellulose acetate film was sent to the stretching step shown in FIG.
It was stretched at 5 °. The draw ratio was 43.5%. After stretching, it was dried at 120 ° C. in a drying step to obtain a retardation plate. The water content was measured and found to be 1.5% by mass. The film thickness was 102 μm. Samples were cut out from the obtained retardation plate at the center and both ends in the width direction, the humidity was controlled for 2 hours in an atmosphere of 25 ° C. and 60% RH, and then the optical characteristics were measured. The results are shown in Table 4.

(Production of Retardation Plate 3) Roll-shaped cellulose acetate film 1 obtained by film formation was slit at both ends to have a width of 920 mm, and then attached to a stretching machine consisting of a water-containing step, a stretching step and a drying step. It was The water-containing step and the stretching step of the stretching machine were set in a constant temperature water tank, heated to 85 ° C, and kept constant. In the water-containing step, the film was sent out into a stretching machine and immersed in a constant temperature water bath for 3 minutes. Then, it was stretched at 45 ° with respect to the longitudinal direction in the stretching process shown in FIG. The draw ratio was 45%. After stretching, it was dried at 120 ° C. in a drying step to obtain a retardation plate. The water content was measured and found to be 1.5% by mass. The film thickness is 98μ
It was m. Samples were cut out from the obtained retardation plate at the center and both ends in the width direction, and the temperature was 25 ° C. and 60% RH.
After controlling the humidity for 2 hours in the atmosphere, the optical characteristics were measured.
The results are shown in Table 4.

(Production of Retardation Plate 4) The roll-shaped cellulose acetate film 2 obtained by film formation is slit at both ends to have a width of 920 mm, and the feeding section of a stretching machine comprising a high humidity step, a stretching step and a drying step. Attached to. Temperature and humidity 8
The film was sent to a high humidity process set at 5 ° C. and 95% RH to absorb moisture for 5 minutes. A part of the sample was cut out and the water content was measured and found to be 4.6% by mass. The wet heat treated cellulose acetate film was sent to the stretching step shown in FIG.
It was stretched at 5 °. The draw ratio was 43.5%. After stretching, it was dried at 120 ° C. in a drying step to obtain a retardation plate. The water content was measured and found to be 1.4% by mass. The film thickness was 100 μm. Samples were cut out from the obtained retardation plate at the center and both ends in the width direction, the humidity was controlled for 2 hours in an atmosphere of 25 ° C. and 60% RH, and then the optical characteristics were measured. The results are shown in Table 4.

(Production of Retardation Plate 5) The roll-shaped cellulose acetate film 3 obtained by film formation is slit at both ends to have a width of 920 mm, and the feeding section of a stretching machine comprising a high humidity step, a stretching step and a drying step. Attached to. Temperature and humidity 8
The film was sent to a high humidity process set at 5 ° C. and 95% RH to absorb moisture for 5 minutes. A part of the sample was cut out and the water content was measured and found to be 5.2% by mass. The wet heat treated cellulose acetate film was sent to the stretching step shown in FIG.
It was stretched at 5 °. The draw ratio was 44.5%. After stretching, it was dried at 120 ° C. in a drying step to obtain a retardation plate. The water content was measured and found to be 1.4% by mass. The film thickness was 98 μm. Samples were cut out from the obtained retardation plate at the center and both ends in the width direction, the humidity was controlled for 2 hours in an atmosphere of 25 ° C. and 60% RH, and then the optical characteristics were measured. The results are shown in Table 4.

(Production of Retardation Plate 6) The roll-shaped cellulose acetate film 2 obtained by film formation is slit at both ends to have a width of 920 mm, and the delivery part of a stretching machine comprising a high humidity step, a stretching step and a drying step. Attached to. Temperature and humidity 8
The film was sent to a high humidity process set at 5 ° C. and 95% RH to absorb moisture for 5 minutes. A part of the sample was cut out and the water content was measured and found to be 4.6% by mass. The wet-heat treated cellulose acetate film was sent to the stretching step shown in FIG. 2 in an atmosphere of 85 ° C. and 95% RH, and stretched at 45 ° in the longitudinal direction. The draw ratio was 44.5%. After stretching, it was dried at 120 ° C. in a drying step to obtain a retardation plate. The water content was measured and found to be 1.3% by mass. The film thickness was 101 μm. Samples were cut out from the obtained retardation plate at the center and both ends in the width direction, the humidity was controlled for 2 hours in an atmosphere of 25 ° C. and 60% RH, and then the optical characteristics were measured. The results are shown in Table 4.

(Production of Retardation Plate 7) The roll-shaped cellulose acetate film 1 obtained by film formation is slit at both ends to have a width of 920 mm, and the delivery part of a stretching machine comprising a humidity control step, a stretching step and a drying step. Attached to. Temperature and humidity 8
The film was sent out to the humidity control process set at 5 ° C. and 95% RH and allowed to absorb moisture for 8 minutes. A part of the sample was cut out and the water content was measured and found to be 5.2% by mass. The wet heat treated cellulose acetate film was sent to the stretching step shown in FIG.
It was stretched so as to be 0 °. The draw ratio was 42.5%. After stretching, it was dried at 120 ° C. in a drying step to obtain a retardation plate. The water content was measured and found to be 1.5% by mass. The film thickness was 101 μm. Samples were cut out from the obtained retardation plate at the center and both ends in the width direction, the humidity was controlled for 2 hours in an atmosphere of 25 ° C. and 60% RH, and then the optical characteristics were measured. The results are shown in Table 4.

(Preparation of Retardation Plate 8) The roll-shaped cellulose acetate film 1 obtained by film formation is slit at both ends to have a width of 920 mm, and the delivery part of a stretching machine comprising a humidity control step, a stretching step and a drying step. Attached to. Temperature and humidity 8
The film was sent out to the humidity control step set at 5 ° C. and 95% RH to absorb moisture for 5 minutes. A part of the sample was cut out and the water content was measured and found to be 4.6% by mass. The wet heat treated cellulose acetate film was sent to the stretching step shown in FIG.
It was stretched so as to be 0 °. The draw ratio was 45.2%. After stretching, it was dried at 120 ° C. in a drying step to obtain a retardation plate. The water content was measured and found to be 1.52% by mass. The film thickness was 99 μm. Samples were cut out from the obtained retardation plate at the center and both ends in the width direction, the humidity was controlled for 2 hours in an atmosphere of 25 ° C. and 60% RH, and then the optical characteristics were measured. The results are shown in Table 4.

[0138]

[Table 4]

(Preparation of linearly polarizing film) Average degree of polymerization: 400
Polyvinyl alcohol having a saponification degree of 0 and 99.8 mol% was dissolved in water to obtain a 4.0% aqueous solution. This solution was cast by a band, dried, stripped from the band, stretched in the casting direction by dry, and then immersed as it was in an aqueous solution of 0.5 g / l iodine and 50 g / l potassium iodide at 30 ° C. for 1 minute. ,
Then boric acid 100 g / l, potassium iodide 60 g / l
Was dipped in the aqueous solution of 70 ° C. for 5 minutes, further washed with water in a water-washed layer at 20 ° C. for 10 seconds, and dried at 80 ° C. for 5 minutes to obtain a long polarizing film, which was wound up on a roll. The film had a width of 960 mm and a thickness of 20 μm.

(Production of Circular Polarizing Plates 1, 4 to 8) Produced long retardation plates 1, 4 to 8, the long linear polarizing film produced above, and long roll of cellulose acetate. A transparent protective film made of a film (Fujitac, manufactured by Fuji Photo Film Co., Ltd.) was laminated in this order with a roll to roll to prepare circularly polarizing plates 1 and 4 to 8. When the optical properties of the obtained circularly polarizing plates 1 and 4 to 8 were examined, almost perfect circularly polarized light was achieved in a wide wavelength range (450 to 590 nm).

(Production of Liquid Crystal Display Device) A mother glass substrate provided with an ITO transparent electrode and a mother glass substrate provided with an aluminum reflective electrode having fine irregularities were prepared. A polyimide alignment film (SE-7992, manufactured by Nissan Chemical Industries, Ltd.) was formed on each of the two glass substrates on the electrode side, and a rubbing treatment was performed. Two substrates were stacked with the alignment films facing each other through a 1.7 μm spacer. The orientation of the substrate was adjusted so that the rubbing directions of the two alignment films intersect at an angle of 110 °. Liquid crystal (MLC-6252, manufactured by Merck) is injected into the gap between the substrates,
A liquid crystal layer was formed. In this way, the twist angle is 70
A TN type liquid crystal cell having a value of ° and Δnd of 269 nm was produced.

A long circular polarizing plate 1 was attached to the side of the glass substrate provided with the ITO transparent electrode and cut into a desired size to manufacture a reflection type liquid crystal display device. A rectangular wave voltage of 1 kHz was applied to the produced reflective liquid crystal display device. When visually evaluated with white display of 1.5 V and black display of 4.5 V, it was confirmed that there was no tint in both white display and black display, and neutral gray was displayed.

[0143]

According to the present invention, it is possible to manufacture a one-piece wide band λ / 4 plate having excellent viewing angle characteristics and excellent productivity. Further, by stretching the retardation film in a direction that is neither parallel nor perpendicular to the longitudinal direction of the film,
Two-roll bonding is possible, and a circularly polarizing plate with good yield and excellent display quality can be manufactured.
Furthermore, by using the circularly polarizing plate in a liquid crystal display device, a liquid crystal display device having excellent display quality (particularly a reflective liquid crystal display device,
A semi-transmissive liquid crystal display device) can be manufactured.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing an example of a method of obliquely stretching a polymer film.

FIG. 2 is a schematic plan view showing an example of a method of obliquely stretching a polymer film.

[Explanation of symbols]

(A) Film introducing direction (b) Film conveying direction to the next step (a) Step of introducing the film (b) Step of stretching the film (c) Step of sending the stretched film to the next step A1 Bite position and starting point of film stretching (substantially holding start point: right) B1 Biting position into holding means of film (left) C1 Starting point of film stretching (substantially holding start point: left) Cx Film release position and film Stretching end point reference position (substantially holding release point: left) Ay Film stretching end point reference position (substantially holding release point:
Right) | L1-L2 | Stroke difference between left and right film holding means W Substantial width θ at the end of the stretching process of the film θ Angle between the stretching direction and the film advancing direction 11 Center line of the introducing side film 12 Center of the film sent to the next process Line 13 Trajectory of film holding means (left) 14 Trajectory of film holding means (right) 15 Introducing film 16 Film 17 and 17 'sent to the next process Left and right film holding start (biting) points 18 and 18' Left and right Departure point from film holding means 21 Center line of introduction side film 22 Center line of film sent to next step 23 Trail of film holding means (left) 24 Trail of film holding means (right) 25 Introduction side film 26 Next step Films 27, 27 'to be fed Left and right film holding start (biting) points 28, 28' Left and right film holding means separating points

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) B29L 7:00 B29L 7:00 11:00 11:00 C08L 1:12 C08L 1:12 F term (reference) 2H049 BA02 BA03 BA06 BA07 BB03 BB33 BB49 BC03 BC09 BC22 2H091 FA11 FB02 FC08 FC30 FD07 FD14 GA01 GA17 KA02 LA03 LA11 LA12 LA16 4F071 AA09 AF29 AF35 AG31 AH19 BC01 4F210 AA01 AG01 AH73 QC01 QG01 QG18

Claims (3)

[Claims] 1. A long cellulose acetate film is adjusted so that the water content thereof is 2.0% by mass or more and 20.0% by mass or less, and the film is oriented in a direction that is neither parallel nor perpendicular to the longitudinal direction. By stretching, the retardation value (Re450) measured at a wavelength of 450 nm is 60 to 135 nm, the retardation value (Re590) measured at a wavelength of 590 nm is 100 to 170 nm, and 2 nm ≦ Re590-Re450 ≦ 100n.
A retardation plate manufacturing method, characterized in that the retardation plate satisfies the relationship of m. 2. A method for producing a long circular polarizing plate by laminating a long linear polarizing film and a long retardation plate so that their longitudinal directions are parallel to each other. The linear polarizing plate is a long linear polarizing film whose transmission axis is substantially parallel to its longitudinal direction, and the long retardation plate has a long cellulose acetate film whose water content is The retardation value (Re450) measured at a wavelength of 450 nm is adjusted by adjusting the content to 2.0% by mass or more and 20.0% by mass or less and stretching in a direction that is neither parallel nor perpendicular to the longitudinal direction. 60 to 135 nm, and the retardation value (Re590) measured at a wavelength of 590 nm is 100 to 170 n.
m is a retardation plate satisfying a relationship of 2 nm ≦ Re590−Re450 ≦ 100 nm, and a method of manufacturing a circularly polarizing plate. 3. A method of manufacturing an image display device, which comprises laminating a long circular polarizing plate prepared by the method of claim 2 on a transparent substrate made of glass or plastic.