JP2003311823A - Orienting and fixing method for long stretched sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an orienting and fixing method capable of easily obtaining a long stretched sheet having an optical axis in a direction oblique with respect to the longitudinal direction of a film by the use of a raw film having a uniform thickness. <P>SOLUTION: A long thermoplastic resin film is passed through a heating stretching zone and a cooling zone and stretched in an oblique direction having a desired angle with respect to the longitudinal direction of the long film to orient and fix the optical axis in the oblique direction. The boundary of the heating stretching zone and the cooling zone is almost parallel to an optical axis direction. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for fixing the orientation of a long stretched sheet. [0002] An elliptically polarizing plate used in a liquid crystal display device is manufactured by laminating a polarizing plate having optical anisotropy and a retardation plate. That is, it is manufactured by laminating and attaching with an adhesive so that the optical axis of the polarizing plate and the optical axis of the retardation plate have a predetermined angle. On the other hand, since a polarizing plate and a retardation plate are manufactured by stretching a thermoplastic resin film in a longitudinal direction or a transverse direction, an optical axis is in a flow direction of the thermoplastic resin film or a direction perpendicular thereto. Become. FIG. 4 shows an example of a conventional method of cutting a retardation plate, and FIG. 5 shows an example of a conventional method of cutting a polarizing plate. In FIG. 4, reference numeral 51 denotes a retardation film produced by stretching a thermoplastic resin film in the longitudinal uniaxial direction, and has an optical axis 52 in the stretching direction of the film. Therefore, the phase difference plates 53 are obtained by cutting in the direction perpendicular to the stretching direction. However, in general, the optical axis 52 is not always orthogonal to the cutting direction. Reference numeral 71 denotes a roll of a retardation film. In FIG. 5, reference numeral 54 denotes a polarizing film produced by stretching a thermoplastic resin film in a longitudinal uniaxial direction, and has an optical axis 55 in the stretching direction of the film. Accordingly, the polarizing plates 56, 56 are obtained by being cut obliquely in the stretching direction. Incidentally, reference numeral 74 denotes a roll of a polarizing film. As a result, the directions of the optical axes of the phase difference plate and the polarizing plate become different, so that when the phase difference plate 53 and the polarizing plate 56 are overlapped as shown in FIG. The directions of the optical axis 52 and the optical axis 55 of the polarizing plate 56 are different, and an elliptically polarizing plate is obtained. However, since the cutting directions of the stretched films are different from each other, it is necessary to separately perform three steps of a cutting step and a sticking step for each film, which complicates the work process, increases the work process loss, and increases the finish. There is a drawback that the efficiency is low and the manufacturing cost is high. Japanese Patent Application Laid-Open No. 2001-281452 discloses that a polyvinyl alcohol film is obliquely stretched in the direction of 10 to 80 degrees with respect to the MD direction so that the optical axis is inclined in the direction of 10 to 80 degrees with respect to the MD direction. A method for producing an optical film is described. It is considered that the use of the obliquely-aligned polarizing plate obtained by this method can eliminate the above-mentioned disadvantage. However, in this method, since the left and right sides are braked at different speeds, it is necessary to change the thickness of the raw film before stretching so as to correct the thickness difference, which is difficult to manufacture. In order to manufacture an optical film, it is necessary to prepare a raw material suitable for each, and it is considered that production efficiency is poor. Furthermore, there is no description about a method or an apparatus for fixing the orientation of a film stretched in an oblique direction, and it is considered that the orientation direction, that is, the direction of an optical axis tends to vary. SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, an object of the present invention is to use a raw film having a uniform thickness and a long stretched sheet having an optical axis oblique to the stretching direction. To provide an alignment fixing method that can easily obtain the alignment. According to the method for fixing the orientation of a long stretched sheet of the present invention, a long thermoplastic resin film is passed through a heating stretching zone and a cooling zone so as to extend in the longitudinal direction of the long film. By stretching in an oblique direction having a desired angle, the orientation is fixed so that the optical axis is in an oblique direction, wherein the boundary between the heating stretching zone and the cooling zone is substantially parallel to the optical axis direction. It is a feature. As the thermoplastic resin used in the present invention, any resin conventionally used for an optical film can be used, and an optically transparent resin is preferable. For example, polycarbonate, polysulfone, polyethersulfone ,
Examples include polystyrene, polyolefin, polyvinyl alcohol, polyvinylidene fluoride, poly (meth) acrylate, polyethylene terephthalate, cellulose ester, and polynorbornene. The thickness of the thermoplastic resin film is not particularly limited, but a film having a thickness of 40 to 100 μm is generally used. Next, the present invention will be described with reference to the drawings.
FIG. 1 is a plan view showing an example of a stretching apparatus used in the method for fixing the orientation of a long stretched sheet of the present invention. In the drawing, reference numeral 1 denotes a heating device, which is a preheating zone 1
1. The heating and stretching zone 12 and the cooling zone 13 are connected and formed. Heat stretching zone 12 and cooling zone 1
Reference numeral 3 indicates that the boundary is connected substantially parallel to the optical axis direction of the long stretched film to be manufactured. Reference numerals 2 and 21 denote rails provided on the left and right sides of the heating device 1, and jigs 3 and 3 for holding the ends of the long thermoplastic resin film on the respective rails 2 and 21.
1 is movably mounted. Although the rail 2 is straight, the rail 21 has a wavy shape in the heating and stretching zone 12 as shown in the schematic front view of FIG. Are the same for the heating stretching distances 12a and 12b. Therefore,
When the jigs 3 and 31 move at the same speed, the jig 31 moves the heating extension distance 12b while the jig 3 moves the heating extension distance 12a. Reference numeral 6 denotes a roll on which the long thermoplastic resin film raw material 4 is wound, and 7 denotes a roll on which the long stretched sheet 5 is wound. The long thermoplastic resin film raw material 4 supplied from the roll 6 is gripped by jigs 3 and 31, preheated in a preheating zone 11, and sent to a heating stretching zone 12.
In the heating and stretching zone 2, the jig 31 moves by a distance of 12b while the jig 3 moves by a distance of 12a, so that the raw long thermoplastic resin film 4 is stretched in the direction of arrow A. The temperature of the heating stretching zone 12 may be approximately the same as the glass transition temperature of the thermoplastic resin film to be stretched, and may be appropriately determined according to the required performance of the optical film to be manufactured. The temperature of the cooling zone 13 may be any temperature at which the orientation of the thermoplastic resin film by stretching can be fixed, and is generally set to be equal to or lower than the glass transition temperature of the stretched thermoplastic resin film. The cooling means of the cooling zone 13 is not particularly limited as long as it can perform cooling substantially in parallel to the orientation of the film.
Examples include a heating device such as a halogen heater, a pipe through which a heat medium or a refrigerant passes, and a heating and stretching zone 12 and a cooling zone 1.
A hot-air heating device capable of accurately controlling the temperature at the boundary of No. 3 is preferable. The heating and stretching zone 12 and the cooling zone 13
Means a zone in which the thermoplastic resin film is substantially stretched and a zone in which the orientation generated by the stretching is cooled and fixed, and does not mean a mechanically and structurally independent zone. It means a zone where the temperature is equal to or higher than the stretchable temperature and a zone where the temperature is equal to or lower than the temperature. The elongated stretched sheet 5 stretched and fixed in orientation by cooling is discharged from the cooling zone 13 and rolled.
It is wound around. FIG. 3 is a plan view showing an example of a long stretched sheet manufactured by the method for fixing the orientation of a long stretched sheet according to the present invention. In the figure, reference numeral 5 denotes a long stretched sheet, and an optical axis 8
Is parallel to the boundary direction between the heating stretching zone 12 and the cooling zone 13. Therefore, in order to cut the optical plate 9 from the long stretched sheet 5, it may be cut so as to be orthogonal to the longitudinal direction of the stretched sheet 5 as shown in FIG. Hereinafter, the present invention will be described in detail with reference to examples. Example 1 A polynorbornene film (glass transition temperature: 170 ° C.) having a width of 600 mm, a thickness of 60 μm, and a length of 50 m was drawn using the drawing apparatus shown in FIG. The boundary between the heating and stretching zone 12 and the cooling zone 13 was 45 degrees with respect to the transport direction of the film. The preheating zone 11 and the heating and stretching zone 12 are set at 172 ° C. by a hot air heating method, and the cooling zone 13 is set.
Is set to 160 ° C by the hot air heating method,
It was transported at a speed of m / min. Further, the film is gripped at both ends by jigs 3 and 31, and the jigs 3 and 31 move 2 m / m on rails 2 and 21.
It was stretched by moving at a speed of min. The stretching test was performed 10 times to obtain 10 stretched films. (Comparative Example 1) Ten stretched films were obtained in the same manner as in Example 1 except that the boundary between the heating stretching zone and the cooling zone was perpendicular to the transport direction of the film. Measurement of maximum deviation angle The central portion 40 of each of the obtained ten stretched films was
Between 0 mm, 10 points in the width direction of the film were measured in the optical axis direction, the deviation angle from 45 degrees was measured, and the difference between the largest and smallest angles was shown in Table 1 as the maximum deviation angle. . The measurement was performed using the Otsuka Electronics product name “RET”.
S-2000 ". [Table 1] Since the configuration of the method for fixing the orientation of a long stretched sheet of the present invention is as described above, the optical axis is adjusted to the stretching direction of the long thermoplastic resin film using a uniform raw material. Different optical films can be easily obtained. [0035]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view showing an example of a stretching apparatus used for the method for fixing the orientation of a long stretched sheet of the present invention. FIG. 2 is a schematic front view of a rail 21. FIG. 3 is a plan view showing an example of a long stretched sheet manufactured by the method for fixing the orientation of a long stretched sheet of the present invention. FIG. 4 is a plan view showing an example of a conventional method for cutting a retardation plate. FIG. 5 is a plan view showing an example of a conventional polarizing plate cutting method. FIG. 6 is a plan view illustrating an example of an elliptically polarizing plate. [Description of Signs] 1 stretching apparatus 11 preheating zone 12 heating stretching zones 12a, 12b heating stretching distance 13 cooling zone 2, 21 rail 3, 31 jig 4 long thermoplastic resin film 5 long stretching sheet 8 optical axis

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Masakatsu Tagami             2-1 Hyakuyama, Shimamoto-cho, Mishima-gun, Osaka Sekisui Chemical             Industrial Co., Ltd. F term (reference) 2H049 BA02 BA06 BA25 BC03 BC13                       BC22                 4F210 AA12 AG01 AH73 QA02 QC03                       QD13 QG01 QG17 QL01 QL04                       QL17 QL18

Claims (1)

Claims: 1. A long thermoplastic resin film is passed through a heating stretching zone and a cooling zone, and is stretched in an oblique direction having a desired angle with respect to the longitudinal direction of the long film. A method for fixing the orientation of the elongated stretched sheet so that the optical axis is oblique, wherein the boundary between the heating stretching zone and the cooling zone is substantially parallel to the optical axis direction.