JP2008176280A - Method for producing optical film laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a yield, and to efficiently manufacture an optical film laminate in the manufacturing of the optical film laminate composed of a laminate of a plurality of optical films with their optical orienting axes forming a prescribed angle. <P>SOLUTION: A method for producing the optical film laminate, including performing lamination of a portion of a first optical film produced in a continuous form and provided with an optical orienting axis and a portion of a second optical film produced in a continuous form and provided with an optical orienting axis in a manner such that the orienting axes make a prescribed angle to thereby obtain a laminate intermediate and thereafter cutting the laminate intermediate to thereby obtain an optical film laminate composed of a laminate of the first and the second optical films, is characterized in that at least either the first optical film or the second optical film is cut by a cutting line parallel to or identical with any of the sides constituting the contour of the optical film laminate to obtain a cut piece, followed by lamination of the cut piece and the other optical film, to thereby obtain the laminate intermediate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention mainly relates to a method for producing an optical film laminate, and more particularly, to a method for producing an optical film laminate in which optical films such as a polarizing film and an optical compensation film are laminated.

  In recent years, in a liquid crystal display device, not only a polarizing film but also various optical compensation films have been used in order to improve the visibility defect due to the birefringence of the liquid crystal cell used. In many cases, an optical film laminate in which a compensation film is laminated constitutes a part of the liquid crystal display device.

  By the way, the optical film laminate is manufactured by individually laminating individual optical films such as a polarizing film and an optical compensation film, and bonding them together and cutting them into predetermined dimensions and shapes. As a specific problem in the optical film laminate, each optical film individually has a predetermined optical directivity axis, and when the optical film laminate is produced, the optical film In other words, the target directing axes must be stacked so as to form a predetermined angle.

  Further, when such an optical film laminate is used as a member of a liquid crystal display device, the optical film laminate is cut into a size and shape corresponding to the size and shape of the liquid crystal display device. Even in this case, it is necessary to adjust the optical directional axis of each optical film so as to face a predetermined direction with respect to the shape of the optical film laminate.

  For example, a case where an optical film laminate for a liquid crystal display device in which a polarizing film and a retardation film are laminated and cut into a rectangular shape will be described. One side forming a rectangular outline of the optical film laminate In addition, the absorption axis of the polarizing film and the slow axis of the retardation film must be configured to form a predetermined angle.

  Conventionally, as a method for producing this type of optical film laminate, for example, a method as described in Patent Document 1 below is known. As shown in FIGS. 6 and 7, the method described in Patent Document 1 includes one optical film 101 (for example, a retardation film) formed in a long shape and another optical film formed in a long shape. 102 (for example, a polarizing film) is laminated to form a laminated intermediate 103, and then the laminated intermediate 103 is cut into chips 104 having a predetermined shape (for example, a minute rectangular shape). Here, when the one optical film 101 and the other optical film 102 are laminated, the one optical film 101 and the other optical film 102 have a predetermined angle, that is, the slow axis of the retardation film 101. In consideration of the lamination such that X and the absorption axis Y of the polarizing film form a predetermined angle, the one optical film 101 is formed into a parallelogram-shaped cut piece 101a so that the ends of the two overlapping films coincide. It is characterized by cutting. In this specification, the method is referred to as a conventional A method for convenience.

JP-A-11-231129

  Such a conventional A-type manufacturing method is an earlier conventional method, that is, a method in which one optical film and another optical film are separately cut into chips, and then chip-shaped films are bonded together. Compared with this, work efficiency can be improved.

  Moreover, the following methods are also examined as a manufacturing method of the optical film laminated body different from the conventional type A system. That is, as shown in FIGS. 8 and 9, one optical film 201 (for example, a retardation film) formed in a long shape and another optical film 202 (for example, a polarizing film) formed in a long shape. Are laminated to form a laminated intermediate 203, and then the laminated intermediate 203 is cut into chips 204 having a predetermined shape (for example, a minute rectangular shape), the one optical film 201 and another optical film. When the two optical films 202 are laminated, the one optical film 201 is cut in advance into a rectangular cut piece 201a having a predetermined length, and the cut piece 201a is placed on another optical film 202 at a predetermined angle, that is, the position. Lamination is performed such that the slow axis X of the phase difference film 201 and the absorption axis Y of the polarizing film form a predetermined angle, and a part of one optical film protruding from the other optical film is cut to form an unlaminated portion. In which the laminate of intermediate 203 by laminating moved further cutting the laminate intermediate 203 minute rectangular chip 204. In this specification, the method is referred to as a conventional B method for convenience.

  Such a conventional type B method is one in which when the lamination angle between the longitudinal direction of one optical film and the longitudinal direction of another optical film is shallow, the conventional type A method has an extremely long parallelogram shape. This is made in view of the fact that the optical film must be cut, and such a cutting operation and handling of the film after cutting become difficult. That is, in the conventional type B system, one optical film is cut into a rectangular shape without considering the stacking angle with the other optical film, so that the cutting operation and cutting after the one optical film are performed. It is intended to improve the yield by making effective use of the protruding part by lamination while facilitating the handling of the film piece.

However, in any of the conventional A method and the conventional B method, a step of laminating the laminated intermediate again after laminating one optical film and another film to obtain a laminated intermediate. In the cutting process, an excessive portion that does not satisfy the product shape is inevitably generated, and there is a problem that the yield is lowered.
In other words, in both of the conventional A method and the conventional B method, a portion where a predetermined product shape cannot be secured remains in the vicinity of the periphery of the laminated intermediate, and that portion must be discarded. There is no.

  The present invention has been made in view of such problems of the prior art, and in the case of manufacturing an optical film laminate in which a plurality of optical films are laminated such that the optical directional axis forms a predetermined angle. Therefore, it is an object to improve the yield. Another object of the present invention is to efficiently produce such an optical film laminate.

  The present invention includes a part of a first optical film formed in an elongated shape and having an optical directivity axis, and a part of a second optical film formed in an elongated shape and having an optical directivity axis. Then, after laminating the directional axes to form a predetermined angle to form a laminated intermediate, the laminated intermediate is cut to produce an optical film laminate in which the first and second optical films are laminated. A method for producing an optical film laminate, wherein at least one of the first optical film and the second optical film is parallel to any side constituting the contour of the optical film laminate, or Provided is a method for producing an optical film laminate, wherein the cut piece and the other optical film are laminated by cutting along a matching cutting line to form the laminated intermediate.

According to the method for producing an optical film laminate of the present invention having such a configuration, at least one of the first optical film and the second optical film is used to form an outline of the optical film laminate. After cutting with a cutting line parallel or coincident with the side (hereinafter, this cutting step is also referred to as "first cutting step") to a cut piece, the cut piece and the other optical film are laminated, By using the laminated intermediate, the laminated intermediate is then cut (hereinafter, this cutting step is also referred to as “second cutting step”) to form an optical film laminated body. It is possible to greatly reduce the cutting edge generated in the vicinity.
That is, in any of the manufacturing methods of the conventional type A method and the conventional type B method described above, as in the present invention, the optical film lamination that is a product through the steps of the first cutting step, the laminating step, and the second cutting step. Although the body was created, the cutting lines that cut the film in these first and second cutting steps were not coincident or parallel, so there were many pieces that would not become products. However, according to the present invention, since the cutting lines in the first cutting step and the second cutting step are coincident or parallel to each other, it is possible to greatly reduce the occurrence of a piece that does not become a product.

  In addition, according to the method for producing an optical film laminate according to the present invention, the cutting line in the first cutting step and the cutting line in the second cutting step are coincident or parallel to each other. There is an effect that it is easy to determine a cutting line when cutting the intermediate.

As described above, according to the method for producing an optical film laminate according to the present invention, in the case of producing an optical film laminate in which a plurality of optical films are laminated such that the optical directivity axis forms a predetermined angle. It becomes possible to improve the yield.
Further, according to the present invention, the cutting line in the first cutting step and the cutting line in the second cutting step are coincident or parallel, so that the cutting line can be easily and accurately determined in the second cutting. It becomes possible to manufacture a film laminated body efficiently.

  1-5 is the conceptual diagram which showed one Embodiment of the manufacturing method of the optical film laminated body which concerns on this invention. In this embodiment, the retardation film 1 is used as a first optical film that is formed in a long shape and has an optical directivity axis, and is a second optical film that is formed in a long shape and has an optical directivity axis. A polarizing film 2 is used. Further, in the present embodiment, these optical films are laminated at a predetermined angle to form a rectangular shape composed of a pair of opposed long sides 41 and a pair of opposed short sides 42 as shown in FIG. The case where the optical film laminated body 4 of this is manufactured is demonstrated.

  As shown in FIGS. 1-4, the manufacturing method of the optical film laminated body which concerns on this embodiment is the 1st cutting process (cut | disconnecting the phase difference film 1 which is the 1st optical film formed in the elongate shape ( 1) and a laminating step (layered intermediate 3) by laminating the retardation film 1a cut by the first cutting step on the polarizing film 2 which is the second optical film formed in a long shape. 2) and a second cutting step (FIG. 4) in which the laminated intermediate body 3 is cut to form a plurality of rectangular optical film laminates 4 in which the retardation film 1 and the polarizing film 2 are laminated. It is equipped with.

  Here, the retardation film 1 as the first optical film is a film in which the refractive index of the transmitted light differs depending on the direction in the film plane, and has the maximum refractive index and the most delayed phase of the transmitted light. And a direction (referred to as a fast axis) in which the refractive index is minimum and the phase of transmitted light is most advanced. In this embodiment, the retardation film 1 in which the slow axis is formed in parallel with the long axis of the film formed in a long shape is used as the first optical film, and the slow axis (“X” in the figure) Is an optical directional axis in the first optical film 1.

  Moreover, the polarizing film 2 which is a 2nd optical film has the direction (it is called an absorption axis) which does not permeate | transmit the wavelength of transmitted light in the film surface, and the direction (it is called a transmission axis) which permeate | transmits. In this embodiment, the polarizing film 2 in which an absorption axis is formed in parallel with the long axis of the film formed in a long shape is used as the second optical film, and the absorption axis (indicated by “Y” in the figure). ) As the optical orientation axis in the second optical film.

Furthermore, this embodiment explains the case where the rectangular optical film laminated body 4 by which an outline is comprised by the long side 41 and the short side 42 is created, and the direction parallel to the said long side 41 is used as a reference | standard. An axis (indicated by “Z” in the figure). In addition, an angle formed by the reference axis Z and the slow axis X is expressed as θ1, and an angle formed by the reference axis Z and the absorption axis Y is expressed by θ2.
More specifically, in this embodiment, the angle θ1 formed by the reference axis Z and the slow axis X is 65 °, and the angle θ2 formed by the reference axis Z and the absorption axis Y is 45 °. The case where such an optical film laminated body 4 is produced is demonstrated.

  As shown in FIG. 1, the first cutting step is a step of cutting the retardation film 1, which is the first optical film, into cut pieces 1 a having a desired length L. In the present invention, the film cutting line 11 in the first cutting step is made to coincide with or parallel to any side constituting the outline of the optical film laminate 4 to be created. Here, the sides constituting the contour of the optical film laminate 4 can have any shape depending on the application of the optical film laminate 4, and may be either linear or curved. The cutting line 11 in the first cutting step is determined by selecting an arbitrary side from the sides constituting the contour of the optical film laminate 4 and using the side as a reference. Specifically, it is assumed to coincide with or be parallel to the side.

In this embodiment, the cutting line 11 of the film in the first cutting step is based on the long side 41 among the long side 41 and the short side 42 constituting the outline of the rectangular optical film laminate 4, It is set to be parallel to the long side 41.
Here, the long side 41 is parallel to the reference axis Z in the optical film laminate 4, and the reference axis Z forms an angle θ1 with the slow axis X of the retardation film 1 in the optical film laminate 4. is there. Therefore, the cutting line 11 of the optical film in the first cutting step can be set so as to form an angle θ1 with the slow axis X of the retardation film 1.

  For example, as in the present embodiment, when the angle θ1 formed by the reference axis Z and the slow axis X is 65 ° in the rectangular optical film laminate 4 (shown in FIG. 5) to be created, The angle formed by the cutting line 11 of the retardation film 4 and the slow axis X in one cutting step may be 65 °.

  In addition, the cutting length L of the retardation film 1 in the first cutting step is not particularly limited, and is appropriately set in consideration of the ease of work in cutting the film and handling the film after cutting. Is possible.

  As shown in FIG. 2, the laminating step is a step of laminating the cut piece 1a of the retardation film 1 cut by the first cutting step on the polarizing film 2 as the second optical film. When laminating both films, so as to satisfy the angle formed by the optical orientation axis X of the first optical film and the optical orientation axis Y of the second optical film in the optical film laminate 4 to be prepared, Laminate both films.

In the present embodiment, as shown in FIG. 5, the angle θ formed by the slow axis X and the absorption axis Y in the rectangular optical film laminate 4 to be created is θ1−θ2, so that the slow axis The polarizing film 2 and the retardation film cut piece 1a are laminated so that X and the absorption axis Y form an angle θ1-θ2.
For example, when the angle θ1-θ2 formed by the slow axis X and the absorption axis Y is 20 ° in the rectangular optical film laminate 4 to be created as in this embodiment, in the lamination step, Both films are laminated so as to have such an angle.

  In the present invention, the cutting line 11 in the first cutting step is coincident with or parallel to any side (that is, the reference axis Z) of the optical film laminate 4 to be created. Therefore, the angle between the cutting line 11 and the optical directional axis Y of the second optical film (in this embodiment, the absorption axis Y of the polarizing film) is θ2 (45 ° in this embodiment). You may laminate | stack both films by adjusting an angle.

Furthermore, in this embodiment, after this lamination process, among the laminated retardation film cut pieces 1a, the portion 1b protruding from the polarizing film 2 is cut, and the cut portion 1b is placed in the polarizing film 2. It is set as the lamination | stacking intermediate body by the process laminated | stacked on the non-lamination part of the phase difference film cutting piece 1a. Specifically, as shown in FIG. 3, among the laminated retardation film cut pieces 1a, a triangular portion 1b protruding from the polarizing film 2 is cut, and the cut triangular portion 1b is cut into the first portion. The laminated intermediate is processed by moving parallel to the cutting line 11 in the cutting step and laminating the polarizing film 2 on the portion where the retardation film cut pieces 1a are not laminated.
By such a method, it is possible to effectively use the portion of the retardation film 1 that protrudes from the polarizing film 2 and further improve the yield.

As shown in FIG. 4, the second cutting step is a step of cutting the laminated intermediate body 3 created by the laminating step into a predetermined product shape and dimensions. The product shape and dimensions of the optical film laminate 4 produced by cutting are not particularly limited, and can be appropriately set according to the application of the product.
In the present invention, in the first cutting step, the film cutting line 11 is determined so as to coincide with or be parallel to any side constituting the contour of the optical film laminate 4 to be created. Therefore, in the second cutting step, it is possible to employ a cutting line 21 set so as to coincide with or be parallel to the cutting line 11 cut in the first cutting step.

  In the present embodiment, as shown in FIG. 4, a plurality of cutting lines 21 parallel to the cutting lines 11 cut by the first cutting step and a plurality of cutting lines 22 perpendicular to the cutting lines 21 are used. A plurality of rectangular optical film laminates 4 are created by cutting the laminate intermediate 3.

According to the manufacturing method of the optical film laminated body which concerns on this embodiment, in a 1st cutting process, it corresponds with any side which comprises the outline of the optical film laminated body 4 which should be created, or it becomes parallel. Since the cutting line 11 of the film is determined, when the laminated intermediate 3 is cut into a predetermined product shape and dimensions in the second cutting step, excess pieces that do not satisfy the product shape around the laminated intermediate 3 The generation amount can be reduced, and the yield of the optical film laminate 4 as a product can be increased.
Specifically, as shown in FIG. 4, at the both ends in the width direction of the polarizing film 2 around the laminated intermediate 3, there are generated surplus pieces that do not satisfy the product shape as in the conventional case, but the polarizing film 2. At both ends in the longitudinal direction, excess pieces hardly occur.

  In other words, in both the conventional A method and the conventional B method as described above, when a laminated intermediate formed by laminating optical films is cut to produce an optical film laminate having a predetermined shape, the cutting line is Since the side (cutting line) of the laminated optical film does not coincide with and is not parallel, a large amount of surplus pieces are formed in the peripheral portion of the laminated intermediate after being cut into the optical film laminated body having a predetermined shape. However, in the present invention, the generation of such surplus pieces can be greatly suppressed.

Further, in the first cutting step, the cutting line of the film is determined so as to be coincident with or parallel to any side constituting the contour of the optical film laminate to be created, so that the second cutting When the laminated intermediate is cut in the process, the cutting line can be easily determined, and there is an advantage that the cutting operation is easy and accurate.
That is, in both the conventional A method and the conventional B method as described above, the cutting line constituting the outline of the product is the side of the laminated optical film (the cutting line at the time of film cutting). Therefore, when cutting the laminated intermediate, the cutting line must be determined again with reference to the optical orientation axis of the optical film, and the cutting operation is complicated and erroneous. However, in the present invention, it is easy to determine such a cutting line, and it is possible to prevent an erroneous angle from being set. it can.

In addition, in the said embodiment, although the case where a retardation film and a polarizing film were used as an optical film was demonstrated, as an optical film in this invention, it is not limited to these polarizing films and retardation films, An optical directional axis | shaft Any film having can be employed. Specifically, examples of the optical film having an optical directivity axis in the present invention include a polarizing film and a retardation film, as well as a brightness enhancement film.
Brightness-enhancement film has the property of reflecting linearly polarized light with a predetermined polarization axis or circularly polarized light in a predetermined direction, and transmitting other light, among natural light incident by reflection from a backlight or back side of a liquid crystal display device or the like. It is shown. That is, a polarizing plate in which a brightness enhancement film is laminated with a polarizing plate composed of a polarizer and a protective layer allows light from a light source such as a backlight to enter to obtain transmitted light in a predetermined polarization state, and other than the predetermined polarization state. The reflected light is reflected without being transmitted, and the reflected light is further inverted through a reflective layer provided on the rear side of the reflected light and re-incident on the brightness enhancement plate, thereby increasing the amount of light transmitted through the brightness enhancement film. In addition, the luminance can be improved by supplying polarized light that is not easily absorbed by the polarizer and increasing the amount of light that can be used for liquid crystal image display or the like.

  Moreover, as an optical film in this invention, you may use the optical film formed by laminating | stacking the said film which has an optical directional axis, and the other film which does not have an optical directional axis.

Further, the angle θ formed by the first optical film and the second optical film is not particularly limited, and the direction of the optical directional axis in these optical films and the optical film laminate as a product It can be set as appropriate according to the optical characteristics to be satisfied.
However, an optical film laminate in which the angle θ formed by the longitudinal direction of the first optical film and the longitudinal direction of the second optical film is in the range of 0 ° <θ ≦ 35 ° is manufactured. In the case of the conventional type A method, it is necessary to handle an extremely long optical film cut piece, and it has been difficult to perform a cutting operation and a handling operation after the cutting. Even so, the optical film can be cut to a length that is easy to handle, and there is an advantage that workability does not deteriorate.

  Moreover, in the lamination process in the said embodiment, although the case where it laminates | stacks with a 1st optical film without cut | disconnecting the elongate 2nd optical film was demonstrated, this invention is limited to such an embodiment. Instead of cutting the long second optical film into a predetermined length, the cut pieces may be laminated. In the case where the second optical film is cut in advance, the cutting line is preferably made to coincide with or parallel to any side constituting the contour of the optical film laminate to be prepared.

  Moreover, although the said embodiment demonstrated the case where the optical film laminated body formed by laminating | stacking two optical films was demonstrated, this invention is not limited to this, In addition to the process demonstrated in the said embodiment, others It is also possible to create an optical film laminate in which three or more optical films are laminated by further comprising the step of laminating the optical film.

  In the present invention, the means for laminating and integrating the optical films is not particularly limited, and any method such as a method using an adhesive or a pressure sensitive adhesive can be employed.

  When an optical film laminate is created by the method for producing an optical film laminate shown in the above embodiment, and when an optical film laminate is created by a method for producing an optical film laminate of a conventional A method and a conventional B method Yield contrast was calculated by simulation. As calculation conditions, a retardation film and a polarizing film having a width of about 630 mm are laminated so as to form angles of 5 °, 20 °, 35 °, and 40 ° to form a laminated intermediate, and a product size of 30 mm from each laminated intermediate. The case of cutting a 40 mm optical film laminate was assumed. The width of the retardation film is determined by cutting the portion protruding from the polarizing film, and laminating the cut portion on the retardation film non-laminated portion of the polarizing film. It was determined to have a parallelogram shape so that there was no extra length in the width direction. The calculation results are shown in Table 1 below.

  As shown in Table 1, in the embodiment of the present invention, it is recognized that the length of the cut piece is shortened and the working efficiency is improved as compared with the conventional method, and the yield is also improved.

The conceptual diagram which showed the 1st cutting process which cut | disconnects the phase difference film 1 which is a 1st optical film in the manufacturing method of the optical film laminated body which concerns on one Embodiment of this invention. In the manufacturing method of the optical film laminated body which concerns on one Embodiment of this invention, the lamination process which laminates | stacks the retardation film cutting piece 1a cut | disconnected by the 1st cutting process on the polarizing film 2 which is a 2nd optical film. The conceptual diagram shown. In the method for producing an optical film laminate according to an embodiment of the present invention, a portion 1b of the retardation film cut piece 1a protruding from the polarizing film 2 by the laminating process is cut, and the retardation film in the polarizing film 2 is not yet formed. The conceptual diagram which showed the process laminated | stacked on a lamination | stacking part. The manufacturing method of the optical film laminated body which concerns on one Embodiment of this invention WHEREIN: The 2nd cutting process which cut | disconnects the lamination | stacking intermediate body 3 created by the said lamination process into the optical film laminated body 4 of a predetermined | prescribed product shape is shown. Conceptual diagram. The top view (a) and sectional drawing (b) which expanded and showed the optical film laminated body 4 created by the manufacturing method of the optical film laminated body which concerns on one Embodiment of this invention. The conceptual diagram which showed the process of cut | disconnecting the one optical film 101, and the process of laminating the cut | disconnected cutting piece 101a on the other optical film 102, and making it the lamination | stacking intermediate body 103 in the manufacturing method of the conventional A system. The conceptual diagram which showed the process which cut | disconnects the lamination | stacking intermediate body 103 and makes it the optical film laminated body 104 of a predetermined shape in the manufacturing method of the conventional A system. The conceptual diagram which showed the process of cut | disconnecting the one optical film 201 in the manufacturing method of the conventional B system, and the process of laminating | stacking the cut piece 201a on the other optical film 202, and setting it as the lamination | stacking intermediate body 203. FIG. The conceptual diagram which showed the process which cut | disconnects the lamination | stacking intermediate body 203 and makes it the optical film laminated body 204 of a predetermined shape in the manufacturing method of the conventional type B system.

Explanation of symbols

1 First optical film (retardation film)
1a Cut piece 2 of first optical film 2nd optical film (polarizing film)
3 Laminated Intermediate 4 Optical Film Laminated Body 11 Cutting Line X Optical Directional Axis (Slow Axis) in First Optical Film (Retardation Film)
Y Optical orientation axis (absorption axis) in the second optical film (polarizing film)
Z Reference axis

Claims (4)

A part of the first optical film having an optical directivity axis formed in a long shape and a part of the second optical film having an optical directivity axis formed in an elongated shape are combined with the directivity axis. An optical film laminate for producing an optical film laminate in which the first and second optical films are laminated by laminating the laminated intermediate so as to form a laminated intermediate and then cutting the laminated intermediate A method for manufacturing a body,
Cutting at least one of the first optical film and the second optical film by a cutting line parallel to or coincident with any side constituting the outline of the optical film laminate, Then, the cut piece and the other optical film are laminated to form the laminated intermediate, thereby producing an optical film laminate.   2. The optical film laminate according to claim 1, wherein an angle θ between the longitudinal direction of the first optical film and the longitudinal direction of the second optical film is 0 ° <θ ≦ 35 °. Manufacturing method.   3. The optical film laminate according to claim 1, wherein one of the first and second optical films is a polarizing film, and the other is a retardation film or a brightness enhancement film. Production method.   When the cut piece is laminated on the other optical film, the portion protruding from the other optical film is further cut and laminated on the non-laminated portion of one optical film in the other optical film, thereby The manufacturing method of the optical film laminated body in any one of Claims 1-3 characterized by the above-mentioned.

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