JP2003177245A - Polarizing plate, method for manufacturing the same and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost and long polarizing plate comprising an obliquely stretched polarizing film with which an yield ratio in a polarizing plate stamping step is improved, which has high-performance and which has 650 mm or more working width, a method for manufacturing the same and a liquid crystal display device using the same. <P>SOLUTION: The polarizing plate has at least a polarizing film with polarizing property wherein an absorption axis of the polarizing film is neither parallel nor vertical to the longitudinal direction, has 80% or larger polarization degree at 550 nm, further has 35% or larger transmittance as a single plate at 550 nm and has 650 mm or more working width vertical to the longitudinal direction. The method for manufacturing the same and the liquid crystal display device using the same are proposed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wide and long polarizing plate having an effective width of 650 mm or more, which can obtain a polarizing plate with high yield.
The present invention relates to a method for manufacturing the long polarizing plate and a liquid crystal display device using the polarizing plate.

[0002]

2. Description of the Related Art A polarizing plate is a liquid crystal display device (hereinafter, LCD).
With the spread of, the demand is rapidly increasing. In the polarizing plate, a protective film is generally attached to both sides or one side of a polarizing layer having a polarizing ability via an adhesive layer. The material of the polarizing layer is polyvinyl alcohol (hereinafter PVA)
Is mainly used, and a PVA film is uniaxially stretched, and then dyed with iodine or a dichroic dye, or dyeed and then stretched, and further crosslinked with a boron compound to form a polarizing film for a polarizing layer. It is formed. As the protective film, cellulose triacetate is mainly used because it is optically transparent and has a small birefringence. Since the film is usually uniaxially stretched in the longitudinal direction, the absorption axis of the polarizing film is substantially parallel to the longitudinal direction.

In the conventional LCD, since the transmission axis of the polarizing plate is tilted by 45 ° with respect to the vertical or horizontal direction of the screen, in the punching process of the polarizing plate manufactured in the roll form, the roll longitudinal direction It was punched in the 45 ° direction. However, when punching in the direction of 45 °, there was a problem that a portion that could not be used was generated near the end of the roll, and particularly in a large-sized polarizing plate, the yield was low. Further, there is a problem that it is difficult to reuse the material of the polarizing plate after being bonded, and as a result, the amount of waste increases.

Further, the retardation film is used by being adhered to a polarizing plate or the like forming an LCD for the purpose of preventing coloration and optical compensation such as widening of viewing angle, and has various alignment axes with respect to the transmission axis of the polarizing plate. It is required to set the angle. Conventionally, a method of punching and cutting the periphery so that the orientation axis has a predetermined inclination angle with respect to the side from a film that is uniaxially stretched in the longitudinal or transverse direction, and the reduction of the yield is caused like the polarizing plate. It was a problem.

In order to solve this problem, some methods have been proposed in which the orientation axis of the polymer is tilted at a desired angle with respect to the film transport method. In Japanese Patent Laid-Open No. 2000-9912, while stretching a plastic film uniaxially in the transverse or longitudinal direction, the left and right of the stretching direction are stretched at different speeds in a longitudinal or transverse direction different from the preceding stretching direction to obtain an orientation axis. It has been proposed to incline with respect to the uniaxial stretching direction. However, in this method, for example, when the tenter method is used, a difference in the conveying speed must be provided on the left and right sides, and as a result, deviations, wrinkles, film deviations, etc. occur, and the desired inclination angle (45 ° for the polarizing plate).
Is difficult to obtain. If it is attempted to reduce the left-right speed difference, the stretching process must be lengthened, and the equipment cost becomes very large.

Further, in JP-A-3-182701, a plurality of pairs of left and right film holding points forming an angle of θ with the running direction are provided at both left and right ears of the continuous film, and each pair of film holding points is formed as the film runs. There has been proposed a method for producing a film having a stretching axis at an arbitrary angle θ with respect to the running direction of the film by a mechanism in which the points can be stretched in the direction of θ. However, even in this method, the film traveling speed changes depending on the left and right of the film, and thus the film is wrinkled or wrinkled. In order to alleviate this, it is necessary to make the stretching process extremely long, and there is a drawback that equipment costs increase.

Further, in Japanese Patent Laid-Open No. 2-113920, both ends of the film are gripped between two rows of chucks traveling on tenter rails 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 are generated when obliquely crossed, which is inconvenient for an optical film.

Korean Laid-Open Publication P2001-0051
No. 84 proposes a polarizing plate whose transmission axis is inclined by rubbing treatment. It is generally known that the alignment regulation by rubbing is effective only from the film surface up to the nano-order part, and as a result, the polarizer such as iodine or dichroic dye cannot be sufficiently aligned, resulting in It had the drawback of low polarization performance.

Further, in the conventional stretching method in the longitudinal direction of the roll, the larger the width of the stretched film, the more marked the curvature of the film edge at the high stretch ratio, and the difficulty of handling in the stretching process such as breakage of the film. . Further, when the stretching is performed by using the multi-stage stretching method, there is a difficulty in handling such as control of the roller rotation speed and control of shrinkage and bending of the end portion of the roll film.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polarizing film which is obliquely stretched, which makes it possible to improve the yield in a polarizing plate punching process, and has a high quality and an effective width of 650 m.
An object is to provide an inexpensive long polarizing plate having a length of m or more and a method for manufacturing the same. A further object of the present invention is to provide a liquid crystal display device using the above polarizing plate.

[0011]

Means for Solving the Problems As a result of intensive studies on the method for achieving the above-mentioned object, the inventors have optimized the tension in the longitudinal direction of a polymer film for a polarizing film at the time of stretching and the environmental humidity at the time of stretching. By optimizing the water content during dyeing of the polymer film for membranes and making the swelling ratio after stretching and drying lower than before stretching, the effective width is 650 mm or more without causing cracks, wrinkles, film deviation, etc. The inventors have found a method of obtaining the oblique orientation of. That is, according to the present invention, a polarizing plate and a liquid crystal display device having the following configurations are provided, and the above object of the present invention is achieved. 1. A long polarizing plate having at least a polarizing film having a polarizing ability, wherein the absorption axis of the polarizing film is neither parallel nor perpendicular to the longitudinal direction, the polarization degree is 80% or more at 550 nm, and the single plate transmittance is 35% at 550 nm. %, And the effective width perpendicular to the longitudinal direction is 650 mm or more. 2. A protective film is attached to at least one side,
The angle formed by the slow axis of the protective film and the absorption axis of the polarizing film is 10 °
The polarizing plate according to above 1, which is at least 90 °. 3. A step of forming a polarizing film by holding both ends of a continuously supplied polymer film for a polarizing film by holding means and applying tension while stretching the holding means while advancing in the longitudinal direction of the film to form a polarizing film The method for producing a polarizing plate as described in 1 or 2, wherein in the step of forming the polarizing film, (i) a substantial holding start point at one end of the polymer film to a substantial holding release point. Trajectory L1 of the holding means and the trajectory L2 of the holding means from the substantial holding start point at the other end of the polymer film to the substantial holding release point, and the distance W between the two substantial holding release points.
Satisfies the following formula (1), (ii) maintains the supportability of the polymer film, and has a state in which the volatile content is 5% or more,
Polymer film 100N / m or more 500N in the longitudinal direction
Polarized light according to the above 1 or 2, wherein a constant tension of / m or less is applied and the film is stretched in an atmosphere having an environmental humidity of 50% or more, and (iii) then contracted to reduce the volatile content. Method of manufacturing a plate. Formula (1): | L2-L1 |> 0.4W 4. 4. The method for producing a polarizing plate as described in 3 above, wherein the stretching is performed in an atmosphere having an environmental humidity of 80% or more. 5. The method for producing a polarizing plate as described in 3 or 4, wherein the polymer film for polarizing film is polyvinyl alcohol or modified polyvinyl alcohol. 6. The method according to any one of 3 to 6, which has a step of dyeing a polymer film for a polarizing film with a polarizer and a hardening agent, and sets the water content distribution of the polymer film after the step to 5% or less.
6. The method for producing a polarizing plate according to any one of 5 above. 7. The method for producing a polarizing plate according to any one of the above 3 to 6, wherein the contraction after stretching is performed by drying. 8. 8. The method for producing a polarizing plate as described in 7 above, wherein the swelling rate of the dried polymer film is lower than that before stretching. 9. 9. The method for producing a polarizing plate as described in 8 above, wherein the water content before stretching is 30% or more and the water content after drying is 10% or less. 10. 10. The method for producing a polarizing plate according to any one of 7 to 9 above, which comprises post-heating after adhering a protective film on at least one side of a polymer film stretched after or during drying. 11. 11. The method for producing a polarizing plate as described in 10 above, wherein each of the operations of stretching, drying, laminating a protective film, and post-heating is performed in a consistent continuous line. 12. A liquid crystal display device, wherein the polarizing plate described in 1 or 2 is used for at least one of polarizing plates arranged on both sides of a liquid crystal cell.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The polarizing plate of the present invention has a polarizing film having a polarizing ability, and usually a protective film (protective film) is provided on both sides or one side of the polarizing film via an adhesive layer. Also, usually, a long polarizing plate (usually roll form) is manufactured,
A practical polarizing plate can be obtained by punching it out according to the application. "Polarizing plate" in the present invention
Is used to mean both a long polarizing plate and the punched polarizing plate unless otherwise specified.

As described above, the polarizing plate of the present invention is a long polarizing plate in which the absorption axis is neither parallel nor perpendicular to the longitudinal direction (hereinafter, such a long polarizing plate is simply referred to as a “diagonally oriented” polarizing plate). Sometimes referred to). The angle formed by the longitudinal direction and the absorption axis direction is preferably 10 ° to 90 °, more preferably 20 ° to 70 °, further preferably 40 ° to 50 °, particularly preferably 44 to 46 °. Thereby, a single-plate polarizing plate can be obtained with high efficiency in the punching process from a long polarizing plate. In the present invention, the angle formed by the longitudinal direction and the absorption axis direction can be freely set. Therefore, the optimum angle can be selected even when used in combination with other optical members.

The polarizing plate of the present invention has a single plate transmittance of 5%.
35% or more at 50 nm and 80% at 550 nm polarization degree
The above is characterized. The single plate transmittance is preferably 40% or more, and the polarization degree is preferably 95.0% or more, more preferably 99% or more, and particularly preferably 99.
It is 9% or more. In this specification, unless otherwise specified, the transmittance is a single plate transmittance. Since the polarizing plate of the present invention has excellent single-plate transmittance and polarization degree, it is advantageous because it can increase the contrast when used as a liquid crystal display device. Further, the polarizing plate of the present invention has an effective width perpendicular to the longitudinal direction of 650 mm or more, preferably 1300 mm or more.

The obliquely oriented polarizing plate of the present invention can be easily obtained by the method described below. That is, while obtaining the oblique orientation by stretching the polymer film,
Optimization of longitudinal tension of the polymer film for polarizing film during stretching and environmental humidity during stretching, optimization of water content during dyeing of the polymer film for polarizing film, lowering of swelling ratio after stretching and drying than before stretching It is obtained by things. Furthermore,
It is also preferable to adjust the amount of foreign matter attached to the film before stretching. In the dyeing step, dyeing and dura mater may be performed simultaneously. In order to obtain a wide polarizing plate having an effective width of 650 mm or more according to the present invention, the water content after film dyeing, the environmental humidity during film stretching, the tension in the roll longitudinal direction, and the swelling ratio before and after stretching are optimized. Etc. are important. Each important item will be described below.

<Effective Width> The effective width in the present invention means a polarizing plate in a roll form after a polymer film for a polarizing film is stretched and dried, and a protective film is further attached thereto, and then biting ears are cut off. Means the width in the direction perpendicular to the longitudinal direction of. Since the polymer film for a polarizing film is bitten by the tenter clip, the unstretched bite is continuously left at the end of the film. Not only does the chewing band have no polarization performance, but it also makes it impossible to bond it to the protective film. Therefore, the bite part will be cut off,
In this case, the larger the edge trimming width, the smaller the effective width that can be used as a polarizing plate. In the present invention, the edge trimming width is preferably 10% or less of the film width after stretching, more preferably 5% or less, and particularly preferably 3% or less. The effective width of the polarizing plate of the present invention is 650.
mm or more, preferably 1300 mm or more, which allows the ratio of the edge trimming width to fall within the above range, the ratio of the polymer film for polarizing film that can be used increases, and the cost of the polarizing plate decreases.

<Humidity at Stretching> If the humidity at the time of stretching the film is insufficient, not only the film cannot be stretched, but also the tenter malfunctions. On the other hand, regarding high humidity during stretching,
It is very effective because no phenomenon such as deterioration of polarization performance is observed and the stretching becomes easy. When a film whose volatile content is water, such as polyvinyl alcohol and cellulose acylate, is stretched, it is needless to say that it may be stretched in a high humidity atmosphere. In the case of polyvinyl alcohol, it is preferably 50% or more, more preferably 8%.
It is 0% or more, more preferably 90% or more.

<Tension in the longitudinal direction> In the process of biting the polymer film, stretching and drying, it is necessary to continuously apply tension in the longitudinal direction. When the film is bitten, if the tension is not enough, the biting width becomes small and the film comes off the holding means during stretching. On the other hand, if too much tension is applied, there is a problem that the film cannot be placed on the holding means and the bite cannot be carried out, and the bite part after the biting is curled. In the present invention, it is preferable to perform stretching, drying and winding while applying a constant tension in the longitudinal direction of the film. In the present invention, when both ends of the film are held by the holding means, it is preferable that the film is stretched so as to be easily held. Specifically, a method in which a tension controller applies tension in the longitudinal direction to stretch the film is used.
The tension varies depending on the film state before stretching,
It is preferable that it is not loosened. The tensile strength in the longitudinal direction in the present invention has different suitability values depending on the type of polymer film, the film conveying speed in the longitudinal direction, and the like. As a method of knowing the proper tension, it is preferable to repeat a state in which the film edge is in contact with the roll or lifted up on the transport roll immediately before biting, and 100 N / m or more and 500 N / m or less are preferable, and 350 N / m or more are more preferable. 450N
/ M or less.

<Volume of Volatile Content> In the stretching step, as the difference between the left and right strokes occurs, the film becomes wrinkled and deviated. In order to solve this problem, in the present invention, it is extremely possible to maintain the supportability of the polymer film, to cause the polymer film to have a volatile content of 5% or more before being stretched before stretching, and then shrink it to lower the volatile content. preferable. The volatile content in the present invention represents the volume of the volatile component contained per unit volume of the film, and is the value obtained by dividing the volatile component volume by the film volume. In the present invention, it is preferable to provide at least one step of incorporating a volatile component before stretching the polymer film for polarizing plate. The step of containing a volatile component is to cast a film to contain a solvent, water, etc., a solvent,
It is carried out by dipping in water, coating, spraying, or the like. The dyeing step or the hardening agent addition liquid adding step described in the section of <Dyeing prescription, dyeing method> and <Addition of hardening agent / metal salt> described below may also serve as a step of incorporating volatile matter. When the dyeing step also serves, it is preferable to provide the step of adding the hardening agent-adding liquid before stretching. When the step of adding the hardening agent-adding liquid also serves, the dyeing step may be performed either before or after stretching. In addition, the dyeing step and the stretching step may be performed at the same time before the stretching.

The preferred volatile content depends on the type of polymer film. The maximum volatile content is possible as long as the support of the polymer film is maintained. For polyvinyl alcohol, the volatile content is preferably 10% to 100%.
Cellulose acylate is preferably 10% to 200%.

<Distribution Distribution of Volatile Components> When a long-sized, particularly roll-shaped polarizing plate is produced in an integrated process, it is necessary that there be no unevenness in dyeing or omission. If there is uneven distribution of the volatile components in the film before stretching (difference in the amount of volatile components depending on the location in the film surface), uneven dyeing and loss may occur. Therefore, the content distribution of the volatile component in the film before stretching is preferably small, and is preferably at least 5% or less. The content distribution of the volatile component means the ratio of the larger difference between the maximum value or the minimum value and the average volatile content to the average volatile content of the volatile content defined above. As a method for reducing the content distribution of volatile components, there are methods such as blowing the front and back surfaces of the film with uniform air, squeezing uniformly with a nip roller, and wiping with a wiper (blade, sponge wiping, etc.). Any method may be used as long as the distribution becomes uniform.
10 to 12 show an example of an air blow device, a nip device, and a blade device.

<Water Content, Water Content Distribution> The polymer for the polarizing film of the present invention is preferably polyvinyl alcohol, and in this case, water is preferred as the volatile component. The polarizing plate of the present invention, for the purpose of increasing the stretching ratio in the width direction,
It is preferable that the water content is rapidly lowered after the drawing is performed under high temperature and high humidity in a state where the water content is increased before the drawing. The water content in the present invention is 30% before stretching the polarizing plate.
The above is preferable, and the higher, the more preferable. On the other hand, drying is performed immediately after stretching, but the water content immediately after stretching is 50.
% Or less, and the earlier the water content decreases, the more preferable. Furthermore, when the polarizing film is dried and then bonded to the protective film, the water content is preferably 10% or less, and particularly preferably 5% or less. In the present invention, the water content means the volume of water contained per unit volume of the film, and is the value obtained by dividing the water volume by the film volume.

The water content distribution in the present invention refers to the ratio of the larger difference between the maximum or minimum water content and the average water content to the average water content in the width direction of the roll form film. For example, the minimum water content between both ends of the film is 44.
If the maximum value is 0% and 44.5%, the water content distribution is 0.5%. The water content distribution in the present invention is preferably within 20%, more preferably within 10%, and particularly preferably within 5%. If the water content distribution of the polymer film after the step of dyeing the polarizer and the hardening agent of the present invention is large, it causes unevenness and streaks.

<Consistent Step> In the present invention, after the film is stretched, it has a drying step of shrinking the film to reduce the volatile content, and after the drying or during the drying, a protective film is attached to at least one side of the film, followed by post-heating. It is preferable to have a process. As a specific method for attaching the protective film, during the drying step, the protective film is attached to the film with an adhesive while holding both ends, and then both ends are ear-picked, or after drying, the film is removed from both end holding portions. There is a method such as releasing the film, cutting the edges of the film, and then attaching a protective film. As a method of cutting the edges, a general technique such as a method of cutting with a cutter such as a blade or a method of using a laser can be used. After bonding, post-heating is preferably performed to dry the adhesive and to improve the polarization performance. The post-heating conditions vary depending on the adhesive, but in the case of an aqueous system, it is preferably 30 ° C or higher, more preferably 40 ° C or higher and 100 ° C or lower, and further preferably 50 ° C.
It is above 80 ° C. It is more preferable in terms of performance and production efficiency that these steps are performed on a consistent production line. Next, other requirements relating to the present invention will be described.

<Stretching Method> An example of the method of the present invention for obliquely stretching a polymer film is shown in FIGS. 1 and 2 as a schematic plan view. The stretching method of the present invention comprises a step of introducing a raw film shown in (a) in the direction of arrow (a), a width direction stretching step shown in (b), and a stretched film shown in (c) in the next step. That is, the step of sending in the (b) direction is included. Hereinafter, the term "stretching step" refers to the entire steps for carrying out the stretching method of the present invention, including these steps (a) to (c). The film is continuously introduced from the direction of (a), and B1 is attached to the holding means on the left side when viewed from the upstream side.
First held in terms. At this point, one film edge is not held yet, and no tension is generated in the width direction.
That is, the B1 point is the substantial holding start point of the present invention (hereinafter,
It does not correspond to the “substantial holding start point”). 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 the holding start point A1 on the more downstream side and the center line 11 of the introduction side film from A1.
(Fig. 1) or 21 (Fig. 2)
It is indicated by two points C1 intersecting the trajectory 13 (FIG. 1) or 23 (FIG. 2) of the holding means on the opposite side. 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 the both ends of the film are not the simple biting points 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 difference in left and right strokes by using a tenter type stretching machine as in the present invention, due to mechanical restrictions such as rail length, the biting point into the holding means and the substantial holding start point are often set. 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 satisfied, the object of the present invention is achieved.

In the above, the tilt angle of the orientation axis in the obtained stretched film is 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. can do. For polarizing plates and retardation films, films oriented at 45 ° with respect to the longitudinal direction are often required. In this case, in order to obtain an orientation angle close to 45 °, it is preferable that the following formula (2) is satisfied, and the formula (2): 0.9W <| L1-L2 | <1.1W is more preferable. It is preferable to satisfy 3). Formula (3): 0.97W <| L1-L2 | <1.03W

As long as the formula (1) is satisfied, the concrete structure of the stretching step can be arbitrarily designed in consideration of equipment cost and productivity as illustrated in FIGS.

The film introduction direction (a) into 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 °. For example, with the structure illustrated in FIGS. 1 and 4,
This value can be achieved. In such a method in which the film advancing direction does not substantially change, it is difficult to obtain an orientation angle of 45 ° with respect to the longitudinal direction, which is preferable as a polarizing plate or a retardation film, only by increasing the width of the holding means. .
Therefore, as shown in FIG. 1, | L1-L2 | can be increased by providing a step of once stretching and then contracting. The stretch ratio is preferably 1.1 to 10.0 times, more preferably 2 to 10 times, and the shrinkage ratio thereafter is preferably 10% or more. Further, as shown in FIG. 4, it is also preferable to repeat stretching and shrinking a plurality of times because | L1-L2 | can be increased.

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. From this point of view, as shown in FIGS. 2, 3 and 5, the angle between the film advancing direction at the exit of the step of holding both ends of the film and the substantial stretching direction of the film is inclined by 20 to 70 °. It is preferable to bend the film in a state where both ends of the film are held in the traveling direction.

In the present invention, a device for stretching the film by applying tension while holding both ends is so-called FIG.
A tenter device such as that of FIG. 5 is preferred. In addition to the conventional two-dimensional tenter, it is also possible to use a stretching step in which the gripping means at both ends is spirally provided with a path difference as shown in FIG.

In the case of a tenter type stretching machine, a chain to which a clip is fixed often goes along a rail,
When the stretching method is uneven as shown in FIGS. 1 and 2, as a result of the present invention, as shown in FIGS. 1 and 2, the rail ends are displaced at the process entrance and exit, and the left and right sides are not simultaneously bitten and disengaged. is there. In this case, the substantial process lengths L1 and L2 are not the simple bite-release distances as described above, but the strokes of the portions where the holding means holds both ends of the film, as already described. Be long.

If there is a difference in the advancing speed on the left and right of the film at the exit of the stretching process, wrinkles and 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.

<Elastic Modulus> As for the physical properties of the polymer film before stretching, if the elastic modulus is too low, the shrinkage factor after stretching during stretching becomes low and wrinkles are hard to disappear. On the other hand, if it is too high, the tension applied during stretching becomes large, and it becomes necessary to increase the strength of the portions holding both ends of the film, which increases the load on the machine. The elastic modulus of the film is preferably 0.1 Mpa or more and 500 Mpa or less, more preferably 1 Mpa or more and 100 Mpa or less in Young's modulus.

<Shrinkage: Shrinkage During Stretching and After Stretching> The shrinkage of the stretched polymer film may be carried out at any step during stretching and after stretching. The shrinkage may be such that wrinkles of the polymer film that occur when oriented in an oblique direction are eliminated, and means for shrinking the film include a method of removing volatile matter by applying temperature, but the film is Any means may be used as long as it contracts. A preferable shrinkage ratio of the film is that it shrinks by 1 / sin θ or more using the orientation angle θ with respect to the longitudinal direction.

<Distance from Wrinkle Generation to Wrinkle> The wrinkle of the polymer film generated when the film is oriented in an oblique direction has only to disappear until the substantial holding release point in the present invention. However, if it takes time from the generation of wrinkles to the disappearance of the wrinkles, variations in the stretching direction may occur, and it is preferable that the wrinkles disappear at a transition distance as short as possible from the point where the wrinkles occur. For this purpose, there is a method of increasing the volatilization rate of the volatile content.

<Drying: Drying Speed, Drying Point> Any drying condition may be used as long as the generated wrinkles disappear. However, it is preferable to adjust the drying point so that the drying point comes as short as possible after the desired orientation angle is obtained. From this, it is preferable that the drying rate is as high as possible.

<Drying temperature> The drying conditions may be any as long as the generated wrinkles disappear, but it depends on the film to be stretched. When a polarizing plate is prepared using a polyvinyl alcohol film by the method of the present invention, the temperature is preferably 20 ° C or higher and 100 ° C or lower, more preferably 40 ° C or higher and 90 ° C or lower.

<Swelling ratio> In the present invention, when the polymer film is polyvinyl alcohol and a hardening agent is used, in order to keep the stretched state in an oblique direction without relaxation,
It is preferable that the swelling ratio in water is different before and after stretching.
Specifically, it is preferable that the swelling rate before stretching is high and the swelling rate after stretching / drying is low. More preferably, the swelling ratio in water before stretching is 3% or more, and the swelling ratio after drying is preferably 3% or less.

<Refraction Part> In the present invention, a rail that regulates the locus of the holding means is often required to have a large bending rate.
For the purpose of avoiding interference between film gripping means due to abrupt bending or local stress concentration, it is desirable that the trajectory of the gripping means draws an arc at the bent portion.

<Stretching Speed> In the present invention, the speed at which the film is stretched is 1.1 in terms of the draw ratio per unit time.
Double / minute or more, preferably double / minute or more, and the earlier one is preferable. In addition, the traveling speed in the longitudinal direction is 0.1 m / min or more, preferably 1 m / min or more, and the higher speed is preferable from the viewpoint of productivity. In either case, the upper limit depends on the film to be stretched and the stretching machine.

<Foreign matter> In the present invention, if foreign matter adheres to the polymer film for a polarizing film before stretching, the surface becomes rough, so it is preferable to remove the foreign matter. The presence of foreign matter causes color unevenness and optical unevenness, especially when a polarizing plate is manufactured. Also, until the protective film is attached,
It is also important that foreign matter does not adhere, and it is preferable to manufacture in an environment where floating dust is minimized. The amount of foreign matter in the present invention is a value obtained by dividing the weight of foreign matter adhering to the film surface by the surface area, and represents the number of grams per square meter. The amount of foreign matter is preferably 1 g / m ² or less, more preferably 0.5 g / m ² or less, and the smaller the amount, the more preferable.

The method for removing foreign matter is not particularly limited,
Any method may be used as long as foreign matter can be removed without adversely affecting the polymer film for a polarizing film before stretching. For example, a method of scraping off the foreign matter by blowing a water stream, a method of scraping off the foreign matter by jetting a gas, a method of scraping off the foreign matter using a blade of cloth, rubber or the like can be mentioned.

<Temperature at Stretching> When a polymer film is stretched, if the ambient temperature is low, the polymer cannot be sufficiently stretched, and if it is high, the polymer can be stretched, but the film is cut off by a tenter and the film is cut. The phenomenon is likely to occur. In the present invention, the ambient temperature at the time of stretching the film may be at least the freezing point of the volatile components contained in the film. When the film is polyvinyl alcohol, the temperature is preferably 25 ° C or higher. Also,
When stretching polyvinyl alcohol soaked with iodine / boric acid for producing a polarizing film, the temperature is 25 ° C or higher and 90 ° C or higher.
C. or lower is preferable, and 40.degree. C. or higher and 90.degree. C. or lower is more preferable.

<Polarizing Film> The polymer film to be stretched in the present invention is not particularly limited, and a film made of an appropriate thermoplastic polymer can be used.
Examples of polymers include PVA, polycarbonate, cellulose acylate, polysulfone, and the like.

The thickness of the film before stretching is not particularly limited, but from the viewpoint of stability of film holding and homogeneity of stretching, it is preferably 1 μm to 1 mm, particularly preferably 20 to 200 μm.

When the present invention is used for producing a polarizing film, PVA is preferably used as the polymer. P
VA is usually saponified polyvinyl acetate, but may contain a component copolymerizable with vinyl acetate such as unsaturated carboxylic acid, unsaturated sulfonic acid, olefins, vinyl ethers. . Further, a modified PVA containing an acetoacetyl group, a sulfonic acid group, a carboxyl group, an oxyalkylene group or the like can also be used.

The degree of saponification of PVA is not particularly limited,
From the viewpoint of solubility and the like, 80 to 100 mol% is preferable,
90 to 100 mol% is particularly preferable. Although the degree of polymerization of PVA is not particularly limited, it is preferably 1000 to 10000, and particularly preferably 1500 to 5000.

<Dyeing Formulation, Dyeing Method> A polarizing film is obtained by dyeing a polymer film for a polarizing film, for example, a PVA film with a polarizer, and the dyeing step is carried out by gas phase or liquid phase adsorption. As an example of the case of performing in a liquid phase, when iodine is used as a polarizer, it is performed by immersing a polymer film for a polarizing film such as a PVA film in an iodine-potassium iodide aqueous solution. Further, a hardening agent / metal salt may be contained in this dyeing solution. Iodine is 0.1-20g /
1 and potassium iodide are preferably 1 to 200 g / l, and the weight ratio of iodine to potassium iodide is preferably 1 to 200. The dyeing time is preferably 10 to 5000 seconds, and the liquid temperature is preferably 5 to 60 ° C. As a dyeing method, not only dipping but also any means such as application or spraying of iodine or dye solution can be used. The dyeing step may be performed before or after the stretching step of the present invention, but it is particularly preferable to perform dyeing in a liquid phase before the stretching step because the film is appropriately swollen and the stretching is facilitated.

<Addition of Hardening Agent (Crosslinking Agent), Metal Salt> In the process of producing a polarizing film by stretching a polymer film for polarizing film, for example, a PVA film, it is preferable to use an additive that crosslinks the PVA film. In particular, when the oblique stretching method of the present invention is used, if the PVA film is not sufficiently hardened at the exit of the stretching step, the orientation of the PVA film may shift due to the tension of the step. It is preferable that the crosslinking agent is contained by dipping or coating the solution in the step. The means for applying the hardening agent (crosslinking agent) to the PVA film is not particularly limited, and the film may be dipped in a liquid, coated,
Although any method such as spraying can be used, a dipping method and a coating method are particularly preferable. As a coating means, any known means such as a roll coater, a die coater, a bar coater, a slide coater, and a curtain coater can be used. A method in which a cloth, cotton, or a porous material impregnated with the solution is brought into contact with the film is also preferable. As the hardener (crosslinking agent), those described in US Reissue Patent No. 232897 can be used, but boric acid and borax are practically preferably used. Further, metal salts such as zinc, cobalt, zirconium, iron, nickel and manganese can also be used together.

The hardening agent (crosslinking agent) may be applied before or after being bitten in the stretching machine, and the stretching in the width direction is substantially completed, as shown in FIGS. 1 and 2. It may be performed in any step up to the end of the step (b) in the above example.
A washing / water washing step may be provided after the addition of the hardener.

<Polarizer> It is also preferable to dye with a dichroic dye in addition to iodine. Specific examples of dichroic dyes include dye compounds such as azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes, and anthraquinone dyes. I can give you. Water-soluble compounds are preferable, but not limited thereto. Further, it is preferable that hydrophilic substituents such as sulfonic acid group, amino group and hydroxyl group are introduced into these dichroic molecules. Specific examples of the dichroic molecule include, for example, C.I. Eye. direct. Yellow 12, Sea. Eye. direct. Orange 39, C.I. Eye. direct. Orange 72, C.I. Eye. direct. Red 39, sea. Eye. direct. Red 79, sea. Eye. direct. Red 81, sea. Eye. direct. Red 83, sea. Eye. direct. Red 89, sea. Eye. direct.
Violet 48, C.I. Eye. direct. Blue 67, Sea. Eye. direct. Blue 90, Sea.
Eye. direct. Green 59, C. Eye. Acid. Red 37 and the like, and further, JP-A-62-1
070802, JP-A-1-161202, JP-A-1
-172906, JP-A-1-172907, JP-A-1-183602, JP-A-1-248105, JP-A-1-265205, and JP-A-7-261024. These dichroic molecules are free acids or alkali metal salts, ammonium salts,
Used as a salt of amines. By mixing two or more kinds of these dichroic molecules, a polarizer having various hues can be manufactured. As a polarizing element or a polarizing plate, a compound (dye) that exhibits a black color when the polarization axes thereof are orthogonal to each other or a mixture of various dichroic molecules that exhibits a black color is preferable because both the single plate transmittance and the polarization rate are excellent.

Further, a polyene structure is formed by dehydrating PVA or dehydrochlorinating polyvinyl chloride,
The stretching method of the present invention can also be preferably used for producing a so-called polyvinylene-based polarizing film that obtains polarized light by a conjugated double bond.

<Protective Film> The polarizing plate of the present invention is usually used by sticking a protective film (protective film) on both sides or one side of a polarizing film. The type of the protective film is not particularly limited, and cellulose esters such as cellulose acetate, cellulose acetate butyrate, and cellulose propionate, polycarbonate, polyolefin, polystyrene, polyester and the like can be used.

The protective film is usually supplied in a roll form, and it is preferable that the protective film is continuously attached to a long polarizing plate so that their longitudinal directions coincide with each other. Here, the orientation axis (slow axis) of the protective film may be in any direction, and the orientation axis of the protective film is preferably parallel to the longitudinal direction from the viewpoint of easy operation.

The angle between the slow axis (orientation axis) of the protective film and the absorption axis (stretching axis) of the polarizing film is not particularly limited, either.
It can be appropriately set according to the purpose of the polarizing plate. Since the long polarizing plate of the present invention has an absorption axis that is not parallel to the longitudinal direction, when a protective film whose alignment axis is parallel to the longitudinal direction is continuously attached to the long polarizing plate of the present invention, the A polarizing plate is obtained in which the absorption axis of the film and the orientation axis of the protective film are not parallel. A polarizing plate in which the absorption axis of the polarizing film and the orientation axis of the protective film are attached at an angle that is not parallel has an effect of excellent dimensional stability. This performance is preferably exhibited especially when used in a liquid crystal display device. In particular, the angle formed by the slow axis of the protective film and the absorption axis of the polarizing film is preferably 10 ° or more and less than 90 °, more preferably 40 ° or more and 50 or more.
When it is less than °, the dimensional stability effect is effectively exhibited.

Generally, the retardation of the protective film is preferably low. However, when the absorption axis of the polarizing film and the orientation axis of the protective film are not parallel to each other, especially when the retardation value of the protective film is a certain value or more, Since the axis and the orientation axis (slow axis) of the protective film are skewed,
Linearly polarized light changes to elliptically polarized light, which is not preferable. Therefore,
The retardation of the protective film is preferably 10 nm or less at 632.8 nm, and more preferably 5 nm or less. From the viewpoint of such low retardation, the polymer used as the protective film is particularly preferably cellulose triacetate. Also, Zeonex, Zeonor (both manufactured by Nippon Zeon Co., Ltd.), ARTON (JSR
Polyolefins such as those manufactured by Co., Ltd. are also preferably used. In addition, for example, a non-birefringent optical resin material as described in JP-A No. 8-110402 or JP-A No. 11-293116.

<Adhesive> The adhesive between the polarizing film and the protective layer is not particularly limited, but a PVA resin (acetoacetyl group,
(Including modified PVA having a sulfonic acid group, a carboxyl group, an oxyalkylene group, etc.), an aqueous solution of a boron compound, or the like, among which a PVA-based resin is preferable. The thickness of the adhesive layer after drying is preferably 0.01 to 10 μm, particularly preferably 0.05 to 5 μm.

<Punching> FIG. 7 shows an example of conventional polarizing plate punching, and FIG. 8 shows an example of punching the polarizing plate of the present invention.
In the conventional polarizing plate, as shown in FIG. 7, the absorption axis 71 of the polarized light, that is, the stretching axis coincides with the longitudinal direction 72, whereas the polarizing plate of the present invention, as shown in FIG. The absorption axis 81 of the polarized light, that is, the stretching axis is 4 with respect to the longitudinal direction 82.
It is inclined by 5 °, and this angle corresponds to the angle formed by the absorption axis of the polarizing plate when it is attached to the liquid crystal cell in the LCD and the vertical or horizontal direction of the liquid crystal cell itself. No punching is required. Moreover, as can be seen from FIG. 8, the polarizing plate of the present invention can be manufactured by slitting along the longitudinal direction without punching because the cutting is straight along the longitudinal direction.
Productivity is also outstanding.

<Uses, etc.> The polarizing plate of the present invention can be used for various purposes. However, the inclination angle of the alignment axis is 4 with respect to the longitudinal direction because of the characteristic that the alignment axis is inclined with respect to the longitudinal direction.
The polarizing film at 0 to 50 ° is a polarizing plate for LCD (for example, T
N, STN, OCB, ROCB, ECB, CPA, IP
S, VA, etc. in all liquid crystal modes), organic E
It is preferably used for an antireflection circularly polarizing plate of an L display. Also, various optical members such as λ / 4 plate and λ / 2
It is also suitable when used in combination with a retardation film such as a plate, a viewing angle widening film, an antiglare film, a hard coat film and the like.

[0063]

EXAMPLES In order to explain the present invention in detail, examples will be given below, but the present invention is not limited thereto.

Example 1 A PVA film was prepared by using iodine 1.
Immerse in an aqueous solution of 0 g / l and 120.0 g / l of potassium iodide at 40 ° C. for 90 seconds, and further in an aqueous solution of 40 g / l of boric acid and 30.0 g / l of potassium iodide at 40 ° C.
After soaking for 0 seconds, the tenter stretching machine having the configuration shown in FIG.
Temperature of 62 ° C and humidity of 9 while applying a constant tension of 70 N / m
After stretching once to 7.0 times in a 6% atmosphere, 5.3
The film was shrunk to double its length, and thereafter kept constant in width, dried at 60 ° C., and then removed from the tenter. The water content of the PVA film before the start of stretching was 42.3%, the water content distribution was 3.8%, the swelling ratio was 31.9%, the water content after drying was 4.8%, and the swelling ratio was 2. It was 0%. The difference in transport speed between the left and right tenter clips was less than 0.05%, and the angle between the center line of the film introduced and the center line of the film sent to the next step was 0 °. Where | L1-L2 | is 0.7
m and W were 0.7 m, and there was a relationship of | L1-L2 | = W. Wrinkles and film deformation at the tenter exit were not observed. Furthermore, PVA (PV manufactured by Kuraray Co., Ltd.
A-117H) 3% aqueous solution was used as an adhesive for saponification, Fuji Photo Film Co., Ltd. Fuji Fujic (Cellulose triacetate, retardation value 3.0 nm) was laminated, and dried at 80 ° C. to obtain polarized light having an effective width of 670 mm. I got a plate. The absorption axis direction of the obtained polarizing plate was inclined by 45 ° with respect to the longitudinal direction, and was also inclined by 45 ° with respect to the slow axis of FUJITAC. The transmittance at 550 nm of this polarizing plate was 43.0%, and the polarization degree was 99.94%.

Example 2 A PVA film was prepared by using iodine 1.
Immerse in an aqueous solution of 0 g / l and 120.0 g / l of potassium iodide at 40 ° C. for 90 seconds, and further in an aqueous solution of 40 g / l of boric acid and 30.0 g / l of potassium iodide at 40 ° C.
After soaking for 0 second, the film was introduced into the tenter stretching machine of the form shown in FIG.
Under a constant tension of 62 ° C. and a humidity of 96%, the film was once stretched to 7.0 times and then shrunk to 5.3 times, then kept constant in width, dried at 60 ° C., and then detached from the tenter. . The water content of the PVA film before the start of stretching was 43.1%, the water content distribution was 4.0%, and the swelling ratio was 32.
2%, the water content after drying was 4.2%, and the swelling ratio was 1.
It was 9%. The difference in transport speed between the left and right tenter clips is less than 0.05%, and the angle between the center line of the film introduced and the center line of the film sent to the next step is 0.
It was °. Here, | L1-L2 | was 0.7 m, W was 0.7 m, and there was a relationship of | L1-L2 | = W.
Wrinkles and film deformation at the tenter exit were not observed. Furthermore, PVA (PVA-11 manufactured by Kuraray Co., Ltd.)
7H) Laminated with Fujitac (cellulose triacetate, retardation value 3.0 nm) manufactured by Fuji Photo Film Co., Ltd., which was saponified with a 3% aqueous solution,
Further, it was dried at 80 ° C. to obtain a polarizing plate having an effective width of 680 mm. The absorption axis direction of the obtained polarizing plate was 4 with respect to the longitudinal direction.
It was tilted 5 degrees. The transmittance of this polarizing plate at 550 nm was 43.4%, and the polarization degree was 99.93%.

[Example 3] A PVA film was washed with a water stream of 2.0.
After washing with ion-exchanged water at L / min, air blowing to remove surface moisture and remove foreign substances, iodine 1.0 g
/ L, 40 in an aqueous solution of 120.0 g / l potassium iodide
Immerse at 90 ° C. for 90 seconds and further soak in an aqueous solution of 40 g / l boric acid and 30.0 g / l potassium iodide at 40 ° C. for 120 seconds, and then air blow with an air blower shown in FIG. And then introduced into the tenter stretching machine of the form shown in FIG. 1 and, while applying a constant tension of 375 N / m, at a temperature of 64 ° C. and a humidity of 91%, once stretched to 7.0 times and then up to 5.3 times. After shrinking, the width was kept constant, dried at 60 ° C., and then removed from the tenter. The water content of the PVA film before the start of stretching was 44.2%, the water content distribution was 4.3%, the swelling ratio was 32.7%, the water content after drying was 3.9%, and the swelling ratio was 1. It was 8%. The difference in transport speed between the left and right tenter clips was less than 0.05%, and the angle between the center line of the film introduced and the center line of the film sent to the next step was 0 °. Where | L
1-L2 | is 0.7 m, W is 0.7 m, and | L1-
There was a relationship of L2 | = W. Wrinkles and film deformation at the tenter exit were not observed. Furthermore, PVA
(PVA-117H manufactured by Kuraray Co., Ltd.) A 3% aqueous solution was used as an adhesive, and the product was laminated with Fuji Photo Film Co., Ltd. Fujitac (cellulose triacetate, retardation value 3.0 nm) saponified, and dried at 80 ° C. Thus, a polarizing plate having an effective width of 675 mm was obtained. The absorption axis direction of the obtained polarizing plate was inclined by 45 ° with respect to the longitudinal direction. The transmittance of this polarizing plate at 550 nm was 43.1%, and the polarization degree was 99.98%.

Example 4 A PVA film was washed with a water stream of 2.0.
After washing with ion-exchanged water at L / min, air blowing to remove surface moisture and remove foreign substances, iodine 1.0 g
/ L, 40 in an aqueous solution of 120.0 g / l potassium iodide
Immerse at 90 ° C. for 90 seconds, further soak in an aqueous solution of boric acid 40 g / l and potassium iodide 30.0 g / l at 40 ° C. for 120 seconds, and then blow air with a nip device shown in FIG. 11 to remove surface moisture. After flying, the film was introduced into the tenter stretching machine of the form shown in FIG. 1 while keeping the tension in the longitudinal direction of the film constant.
4. The film was stretched 7.0 times in an atmosphere of temperature 57 ° C. and humidity 95% while applying a constant tension of 360 N / m, and then 5.
The film was contracted up to 3 times, and thereafter the width was kept constant, dried at 60 ° C., and then removed from the tenter. The water content of the PVA film before the stretching was 44.7%, the water content distribution was 4.4%, the swelling ratio was 33.1%, and the water content after drying was 3.7%.
The swelling rate was 1.6%. The difference in transport speed between the left and right tenter clips was less than 0.05%, and the angle between the center line of the film introduced and the center line of the film sent to the next step was 0 °. Where | L1-L2 | is 0.7
m and W were 0.7 m, and there was a relationship of | L1-L2 | = W. Wrinkles and film deformation at the tenter exit were not observed. Furthermore, PVA (PV manufactured by Kuraray Co., Ltd.
A-117H) Fuji Photo Film Co., Ltd. Fujitac (cellulose triacetate, retardation value 3.0 nm) saponified with a 3% aqueous solution as an adhesive, and then dried at 80 ° C. and polarized with an effective width of 685 mm. I got a plate. The absorption axis direction of the obtained polarizing plate was inclined by 45 ° with respect to the longitudinal direction. The transmittance of this polarizing plate at 550 nm was 43.9%, and the polarization degree was 99.97%.

Example 5: Preparation of Liquid Crystal Display Device Next, as shown in FIG. 9, the iodine type polarizing plate 91 prepared in Example 2,
An LCD was prepared by bonding 92 to two polarizing plates sandwiching a liquid crystal cell 93 of the LCD, and using the polarizing plate 91 as a display side polarizing plate to the liquid crystal cell 93 via an adhesive. The LCD thus prepared exhibited excellent brightness, viewing angle characteristics, and visibility, and no deterioration in display quality was observed even after 1 month of use at 40 ° C. and 30% RH.

[Comparative Example 1] A PVA film was prepared by using iodine 1.
Immerse in an aqueous solution of 0 g / l and 120.0 g / l of potassium iodide at 40 ° C. for 90 seconds, and further in an aqueous solution of 40 g / l of boric acid and 30.0 g / l of potassium iodide at 40 ° C.
After soaking for 0 seconds, the tenter stretching machine having the configuration shown in FIG.
Temperature of 60 ℃ and humidity of 4 while applying a constant tension of 30 N / m
5.3 times after being stretched to 7.0 times in a 5% atmosphere
The film was shrunk to double its length, and thereafter kept constant in width, dried at 60 ° C., and then removed from the tenter. The water content of the PVA film before the start of stretching was 28.9%, the water content distribution was 7.3%, the swelling ratio was 29.1%, the water content after drying was 8.3%, and the swelling ratio was 6. It was 3%. The difference in transport speed between the left and right tenter clips was less than 0.05%, and the angle between the center line of the film introduced and the center line of the film sent to the next step was 0 °. Where | L1-L2 | is 0.7
m and W were 0.7 m, and there was a relationship of | L1-L2 | = W. Although no wrinkles or film deformation was observed at the tenter outlet, many irregularities were observed. Furthermore, PVA (PVA-117H manufactured by Kuraray Co., Ltd.) was bonded to Fujitac (cellulose triacetate, retardation value 3.0 nm) manufactured by Fuji Photo Film Co., Ltd., which was saponified with an aqueous solution of 3% as an adhesive.
A polarizing plate having an effective width of 450 mm was obtained by drying at 0 ° C. The absorption axis direction of the obtained polarizing plate was inclined by 45 ° with respect to the longitudinal direction. The transmittance of this polarizing plate at 550 nm is 4
The degree of polarization was 0.1% and the degree of polarization was 96.38%.

(Measurement of transmittance at 550 nm and degree of polarization) The transmittance was measured by Shimadzu's own spectrophotometer UV2100. Further, assuming that the transmittance is H0 (%) when two polarizing plates are overlapped with their absorption axes aligned, and the transmittance is H1 (%) when the absorption axes are orthogonal to each other, the polarization degree P is calculated by the following equation. (%) Was calculated. P = [(H0-H1) / (H0 + H1)] ^1/2 × 100

From the comparison between Comparative Example 1 and Examples 1 to 3, it is clear that a polarizing plate having an effective width of 650 mm or more can be obtained by controlling and optimizing the humidity during stretching and the tension in the longitudinal direction of the film. Is. Further, it is apparent from Example 4 that a polarizing plate having a further effective width can be obtained by optimizing the humidity during stretching, the tension in the longitudinal direction of the film, and the water content before and after stretching.

[0072]

EFFECTS OF THE INVENTION According to the present invention, an obliquely long polarizing plate having a high quality and an effective width of 650 mm or more, which is composed of an obliquely stretched polarizing film capable of significantly improving the yield in a polarizing plate punching step, is obtained. A plate and a method for manufacturing the same are provided. Further, a large-sized liquid crystal display device having an excellent display product is provided, which is provided with a low-cost polarizing plate punched from this long and wide polarizing plate.

[Brief description of drawings]

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

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

FIG. 3 is a schematic plan view showing an example of the method of the present invention for obliquely stretching a polymer film.

FIG. 4 is a schematic plan view showing an example of the method of the present invention for obliquely stretching a polymer film.

FIG. 5 is a schematic plan view showing an example of the method of the present invention for obliquely stretching a polymer film.

FIG. 6 is a schematic plan view showing an example of the method of the present invention for obliquely stretching a polymer film.

FIG. 7 is a schematic plan view showing how a conventional polarizing plate is punched out.

FIG. 8 is a schematic plan view showing how a polarizing plate of the present invention is punched out.

9 is a schematic plan view showing the layer structure of the liquid crystal display device of Example 5. FIG.

FIG. 10 is a schematic conceptual view of an air blowing device.

FIG. 11 is a schematic conceptual view of a nip device.

FIG. 12 is a schematic conceptual diagram of a blade device.

[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 detachment points 3 , 43, 53, 63 Trajectory of film holding means (left) 34, 44, 54, 64 Trajectory of film holding means (right) 35, 45, 55, 65 Introducing side film 36, 46, 56, 66 Send to next process Film 71 Absorption axis (stretching axis) 72 Longitudinal direction 81 Absorption axis (stretching axis) 82 Longitudinal direction 91, 92 Iodine type polarizing film (polarizing layer) 93 Liquid crystal cell 94 Backlight 101 Air blow device 111 Nip device 121 Blade device

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kentaro Shirato             Fuji Photo, 210 Nakanuma, Minamiashigara City, Kanagawa Prefecture             Within Film Co., Ltd. F-term (reference) 2H049 BA02 BA27 BB33 BB43 BB51                       BC03 BC09 BC14 BC22                 2H091 FA08X FA08Z FB02 FC08                       KA10 LA12

Claims (12)

[Claims] 1. A long polarizing plate having at least a polarizing film having a polarization ability, wherein the absorption axis of the polarizing film is neither parallel nor perpendicular to the longitudinal direction, and the polarization degree is 80% or more at 550 nm and single plate transmission. Rate 550
is 35% or more in nm, and the effective width perpendicular to the longitudinal direction is 6
A polarizing plate having a length of 50 mm or more. 2. A protective film is attached to at least one surface, and an angle formed by a slow axis of the protective film and an absorption axis of the polarizing film is 10 ° or more and less than 90 °. The polarizing plate described in. 3. A polarizing film is formed by holding both ends of a continuously supplied polymer film for a polarizing film by holding means and applying tension while stretching the holding means while advancing in the longitudinal direction of the film. The method for producing a polarizing plate according to claim 1 or 2, further comprising the step of: (i) from the substantial holding start point of one end of the polymer film in the step of forming the polarizing film. Trajectory L1 of the holding means to the substantial holding release point, trajectory L2 of the holding means from the substantial holding start point at the other end of the polymer film to the substantial holding release point, and two substantial holding release points The distance W satisfies the following formula (1), (ii) the support of the polymer film is maintained, the volatile content is 5% or more, and 100 N / m or more and 500 N / m or more in the longitudinal direction of the polymer film. 2. A lower constant tension is applied, and the film is stretched in an atmosphere having an ambient humidity of 50% or more, and (iii) then contracted to reduce the volatile content.
Alternatively, the method for producing a polarizing plate according to item 2. Formula (1): | L2-L1 |> 0.4W 4. The method for producing a polarizing plate according to claim 3, wherein the stretching is performed in an atmosphere having an environmental humidity of 80% or more. 5. The method for producing a polarizing plate according to claim 3, wherein the polymer film for polarizing film is polyvinyl alcohol or modified polyvinyl alcohol. 6. The method of dyeing a polymer film for a polarizing film with a polarizer and a hardening agent, wherein the water content distribution of the polymer film after the step is 5% or less. 6. The method for manufacturing a polarizing plate according to any one of 5 to 5. 7. The method for producing a polarizing plate according to claim 3, wherein the contraction after stretching is performed by drying. 8. The method for producing a polarizing plate according to claim 7, wherein the swelling rate of the dried polymer film is lower than that before stretching. 9. The method for producing a polarizing plate according to claim 8, wherein the water content before stretching is 30% or more and the water content after drying is 10% or less. 10. The polarizing plate according to claim 7, wherein after drying or after a protective film is attached to at least one surface of the polymer film stretched during drying, post-heating is performed. Production method. 11. The method for producing a polarizing plate according to claim 10, wherein the operations of stretching, drying, laminating a protective film, and post-heating are performed in a continuous continuous line. 12. A liquid crystal display device, wherein the polarizing plate according to claim 1 or 2 is used for at least one of polarizing plates arranged on both sides of a liquid crystal cell.