JP2010113116A - Method of peeling optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of peeling an optical film, in which the optical film is easily peeled off without a fear for breakage or flaw when peeling the optical film from a protective film. <P>SOLUTION: In the method of peeling optical film, a mother sheet is composed of: a first protective film; a plurality of optical films which are laminated on one surface of the first protective film and has lens shapes formed on one surface of the optical films; and a second protective film which is laminated on the surface opposite to the side facing the first protective film of the plurality of optical films. The mother sheet is subjected to the following processes 1 to 3 in order: (1) curving the mother sheet such that the second protective film side becomes protruded and peeling only the edge part of the optical films on the boundary between the first protective film and the optical films; (2) completely peeling the second protective film from the optical films; and (3) completely peeling the remainder of an adhesion portion of the first protective film from the optical films. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical film peeling method excellent in workability when each sheet is incorporated during production of a backlight for a liquid crystal display device.

  Liquid crystal display devices are used in various applications such as notebook computers and mobile phone devices, televisions, monitors, car navigation systems, and the like. The liquid crystal display device incorporates a backlight unit serving as a light source, and is configured to display by controlling light beams from the backlight unit through a liquid crystal cell. The characteristic required for this backlight unit is not only as a light source that emits light, but also to make the entire screen shine brightly and uniformly.

  The configuration of the backlight unit can be roughly divided into two. One is a method called a direct type backlight. This is a system that is preferably used for television applications that require large size and high brightness, but the basic configuration is characterized by a structure in which fluorescent tubes are arranged directly behind the screen. By arranging a plurality of linear or partially linear fluorescent tubes in parallel at the back of the screen, it is possible to cope with a large screen and to secure sufficient brightness. Another method is called a sidelight type backlight. This is a method mainly used for mobile phones, notebook computers, etc., which are required to be thin and small, for example, but is characterized by using a light guide plate as a basic configuration. In the case of a sidelight-type backlight, a fluorescent tube is installed on the side surface of the light guide plate, light is incident on the light guide plate from the side surface, and light is propagated throughout the surface while totally reflecting inside the light guide plate. A part of the light is removed from the total reflection condition by diffusing dots or the like applied to the back surface of the light, and the light is collected from the front surface of the light guide plate, thereby functioning as a backlight, that is, a surface light source. In the case of a sidelight type backlight, in addition to these configurations, a reflection film that functions to reflect and reuse light leaking from the back surface of the light guide plate, and a diffusion sheet that equalizes the light emitted from the front surface of the light guide plate Many types of optical films are used, such as a light collecting sheet represented by a prism sheet that improves the front brightness and a brightness improving sheet that improves the brightness on the liquid crystal panel (Patent Documents 1 and 2).

  When producing a backlight, for example, in the case of a cellular phone, a light guide plate is fitted into a frame, a reflection plate is laminated on one side, a diffusion sheet and a prism sheet are laminated on the other, and fixed with a frame-like tape called a rim tape.

  In order to prevent scratches, the sheets have a protective film on one side or both sides, and a process for peeling the protective film is required when the sheet is incorporated into a backlight.

In the case of a small liquid crystal display device, since the sheets are also small, a multi-sided sheet (in the present invention, this is called a mother sheet) on which a plurality of cut optical films are mounted using at least one protective film as a mount In general, it is used for backlight production.
Japanese Patent No. 2670518 JP-A-9-21908

However, if the protective film is too thin, the mother sheet itself does not have rigidity, so the handleability is poor, and when the optical film is cut, it becomes easy to punch out the protective film that becomes the mount, and the yield decreases. To do. Furthermore, when peeling off the optical film from the protective film, if the adhesion between the films is too strong, it becomes difficult to peel off the optical film, resulting in poor productivity, or the optical film is broken or scratched. It becomes easy to stick and the yield decreases.
On the contrary, if the thickness of the optical film is too thin, the above-described problems will be further enhanced. In other words, handling and productivity are inferior and, of course, breakage and scratches easily occur.

  Therefore, in view of the background of the conventional technology, the present invention provides an optical film peeling method and mother sheet excellent in mother sheet productivity and handleability.

The present invention employs the following means in order to solve such problems. That is, facing the first protective film, the plurality of optical films having a lens shape formed on one side of the first protective film, and the first protective film of the plurality of optical films In the mother sheet | seat comprised with the 2nd protective film laminated | stacked on the surface on the opposite side, it is the peeling method of the optical film which performs the next process in order of 1-3.
1. The mother sheet is curved so that the second protective film side is convex, and only the end of the optical film is peeled off at the interface between the first protective film and the optical film.
2. The second protective film is completely peeled from the optical film.
3. The first protective film is peeled off completely from the optical film.

  ADVANTAGE OF THE INVENTION According to this invention, there exists an advantage that the peeling method of the optical film which can be peeled easily can be provided, without fear of making a break and a damage | wound when peeling an optical film from a protective film.

The present invention is not only excellent in the above-mentioned problems, that is, productivity and handleability, but also intensively studied on a process that is not easily broken or scratched in the peeling operation. The first protective film and the first protective film A plurality of optical films having a lens shape formed on one surface and a second protective film laminated on the surface opposite to the side facing the first protective film of the plurality of optical films. In the mother sheet composed of the following, the following steps were unexpectedly solved by peeling the optical film in the order of 1 to 3, and the present invention was reached. is there.
1. The mother sheet is curved so that the second protective film side is convex, and only the end of the optical film is peeled off at the interface between the first protective film and the optical film.
2. The second protective film is completely peeled from the optical film.
3. The first protective film is peeled off completely from the optical film.

  The protective film will be described. Examples of the material for the protective film include polyethylene terephthalate, polyethylene-2,6-naphthalate, polypropylene terephthalate, polybutylene terephthalate, cyclohexanedimethanol copolymer polyester resin, isophthalic acid copolymer polyester resin, spiroglycol copolymer polyester resin, and fluorene. Polyester resins such as copolyester resins, polyolefin resins such as polyethylene, polypropylene, polymethylpentene and alicyclic olefin copolymer resins, acrylic resins such as polymethyl methacrylate, polycarbonate, polystyrene, polyamide, polyether, polyesteramide , Polyetheresters, polyvinyl chloride, copolymers containing these as components, or mixtures of these resins Sex resins. Among these, in terms of mechanical strength and workability, polyethylene, polypropylene, polyethylene terephthalate, copolymers with other components based on these, or polyester resins such as a mixture are more preferably used.

  About the thickness of a protective film, in the 1st protective film, Preferably it is 60-150 micrometers, More preferably, it is 70-130 micrometers. If the thickness is less than 60 μm, the first protective film may be punched out when half-cutting the optical film. Furthermore, it is not preferable because when the first protective film is peeled from the optical film, there is no need for bending. Moreover, in a 2nd protective film, Preferably it is 30-150 micrometers, More preferably, it is 30-100 micrometers, More preferably, it is 30-60 micrometers. When the thickness is 30 μm or less, workability at the time of peeling from the optical film is deteriorated and the optical film may be damaged. When the thickness is more than 100 μm, it is difficult to half-cut the optical film.

  The peel strength of the protective film to the optical film is the 180 ° peel peel strength at which the test angle is 180 ° and the test speed is 300 mm / min. The peel strength between the first protective film and the optical film is The peel strength between the protective film 2 and the optical film is preferably 0.1 N / 25 mm or less, but if it is smaller than 0.005 N / 25 mm, the adhesion to the optical film may be deteriorated.

  Further, when the mother sheet in the present invention is a mother sheet having a form in which the first protective film is larger than the optical film product and the second protective film is cut to the same size as the optical film product, the mother sheet More preferably, the optical film product is peeled off from the first protective film prior to the second protective film when the second protective film is bent outward.

  The protective film is preferably transparent so that appearance inspection of the optical film can be easily performed. Furthermore, it is preferable that the second protective film is colored so that it can be recognized when it is forgotten to peel off.

Next, a method for manufacturing a mother sheet will be described with reference to FIGS. The punching blade die 4 is attached to the press machine 5, the blade die is pressed from the second protective film 3 side, and the second protective film 3 and the optical film 2 are cut. There are pinnacle blades, Thomson blades, NC blades, and the like, but it is preferable to use pinnacle blades in terms of accuracy.
Next, the configuration of the mother sheet will be described. For example, when the optical film is a prism, the orientation of the prism surface may be either up or down as shown in FIG. 2, but it is preferable that the prism surface is directed upward in order to prevent mistakes when incorporated in the backlight. . Further, as shown in FIG. 3, (a) only half-cutting may be performed, (b) unnecessary portions may be removed after half-cutting, and a first protective film and an optical film are attached as shown in (c). The two protective films may be bonded after half-cutting and removing unnecessary portions after combining.

  Below, the measuring method and evaluation method of each Example and a comparative example are demonstrated. In each of the following measurements, each sample was evaluated with an average value of values obtained by performing the measurement three times. The following measurements were all performed under conditions of room temperature of 23 ° C. and humidity of 65%.

(Measurement and evaluation method)
A. Peeling force A sample of a laminated film having a two-layer structure in which a protective film and an optical film are laminated is cut to a width of 25 mm and a length of 180 mm. This sample was subjected to a peel test using an autograph (AGS-J, manufactured by Shimadzu Corporation) at a test speed of 300 mm / min and a test angle of 180 °, and the peel force was measured. The value is determined as the peel force by calculating the average value up to 150 mm after rejecting the data up to 20 mm from the beginning. However, if the length of 150 mm cannot be measured because the sample is small, a plurality of samples are measured so that the total exceeds 150 mm, and the average value is similarly calculated.

B. Cross-sectional observation A cross section of the optical film was cut out, and platinum-palladium was deposited on the cross section. This cross section was observed by taking a photograph at a magnification of 500 using a scanning electron microscope S-2100A manufactured by Hitachi, Ltd., and measuring the dimensions (height and pitch) of the convex shape formed on the surface.

Example 1
(Production of optical film)
Naphthalenedicarboxylic acid 12 mol% copolymerized PET dried at 170 ° C. for 3 hours was used as the surface layer resin, and PET dried at 180 ° C. for 3 hours was used as the core layer resin. Each was melted in a separate extruder at a temperature of 280 ° C., and the laminated resin extruded from the melted three-layer coextrusion die was closely cooled and solidified while applying an electrostatic charge to a cooling drum maintained at 25 ° C. Next, the cast film was stretched 3.0 times at 90 ° C. in the longitudinal direction by a roll type stretching machine, then introduced into a tenter, and transversely stretched 3.0 times at 110 ° C., and then controlled at 238 ° C. Heat treatment was performed in the temperature zone, and the film was cooled to room temperature to obtain a wound thermoplastic film 1. In the thermoplastic film 1, the thickness H of each surface layer was 7.5 μm, the thickness of the core layer was 23 μm, and the total was 38 μm.

Next, the following mold 1 and the thermoplastic film 1 were heated at 120 ° C. for 1 minute, and the mold 1 and the thermoplastic film 1 were pressure-bonded for 60 seconds at a pressure of 2 MPa while maintaining 120 ° C. Then, after cooling to 70 degreeC, the optical film 1 which has the pattern which reversed the shape of the following metal mold | die 1 on the thermoplastic film 1 surface was obtained by releasing a metal mold | die. The total thickness (from the top of the shaping surface to the back surface) of the optical film 1 was 32 μm. The shape of the optical film on one surface (lens surface) of the mold was p = 18 μm and h = 9 μm.
(Mold 1)
In-plane pattern: striped (FIG. 1 (a))
Individual shape: right-angled isosceles triangle (height d: 9 μm)
Pitch between adjacent patterns (p): 18 μm
Size: 100 mm × 100 mm (pattern area).

(Lamination of protective film)
Tretec 7721 (manufactured by Toray Film Processing Co., Ltd.) having a thickness of 100 μm was used as the first protective film, and L-7325 (manufactured by Hitachi Chemical Co., Ltd.) having a thickness of 40 μm was used as the second protective film. A laminated sheet 1 was obtained by simultaneously laminating L-7325 on the lens surface of the optical film and Tretec 7721 on the non-prism surface at a linear pressure of 5 kg / cm. When the peeling force was measured, L-7325 was 0.02 N / 25 mm, and Tretec 7721 was 0.02 N / 25 mm.

(Mother sheet production)
A 3 × 4 cm rectangular pinnacle blade mold was pressed from the L-7325 side of the laminated sheet 1 to cut L-7325 and the optical film 1 to obtain a mother sheet 1.

(Peeling method of optical film and protective film)
As shown in FIG. 4, the mother sheet 1 (a) was bent 90 ° with the first protective film, Tretec 7721 facing down, and the edge of the mother sheet 1 (a) was lifted at the interface between the Tretec 7721 and the optical film 1 b). Next, L-7325 can be peeled off by lifting the end of L-7325 so that L-7325, which is the second protective film, is concave when viewed from the optical film 1 from the part where the float has occurred ( c) The optical film 1 could be taken out easily. At this time, the optical film 1 was not broken or damaged.

(Example 2)
A 3 × 4 cm rectangular pinnacle blade mold was pressed from the L-7325 side of the laminated sheet 1 to cut L-7325 and the optical film 1, and unnecessary portions were removed to obtain a mother sheet 2.
When the peeling method of an optical film and a protective film was used with respect to the mother sheet 2 similarly to Example 1, the optical film 1 was able to be taken out easily. At this time, the optical film 1 was not broken or damaged.

(Example 3)
The laminated sheet 2 was obtained by laminating Tretec 7721 on the non-lens surface of the optical film 1 at a linear pressure of 5 kg / cm.
A 3 × 4 cm rectangular pinnacle blade mold is pressed from the prism surface of the laminated sheet 2, the optical film 1 is cut, and unnecessary portions are removed. The mother sheet 3 was obtained by laminating at / cm. When the peeling force was measured, the prism surface was 0.01 N / 25 mm, and the non-prism surface was 0.02 N / 25 mm.
When the peeling method of an optical film and a protective film was used with respect to the mother sheet 3 similarly to Example 1, the optical film 1 was able to be taken out easily. At this time, the optical film 1 was not broken or damaged.

(Comparative Example 1)
DP-1010 (manufactured by Hitachi Chemical Co., Ltd.) having a thickness of 60 μm was used as the first protective film, and L-7325 (manufactured by Hitachi Chemical Co., Ltd.) having a thickness of 40 μm was used as the second protective film. A laminated sheet 3 was obtained by simultaneously laminating L-7325 on the lens surface of the optical film and DP-1010 on the non-prism surface at a linear pressure of 5 kg / cm. When the peeling force was measured, L-7325 was 0.02 N / 25 mm, and DP-1010 was 0.17 N / 25 mm.
A mother sheet 4 was obtained in the same manner as in Example 1.
When the peeling method of an optical film and a protective film was used with respect to the mother sheet | seat 4 similarly to Example 1, when it tried to peel off the protective film 2, the protective film 2 and an optical film in the ratio of twice in 10 times The product could not be separated and could come off the mount. After that, even if the protective film 2 and the optical film were forcibly separated, the optical film product was broken or damaged, and was no longer usable for the backlight.

  The peeling method of the optical film of this invention is applicable to various fields, such as a member for liquid crystal display devices.

It is the schematic of the manufacturing method of a mother sheet | seat. (A) and (b) schematically illustrate the configuration of the mother sheet. (A)-(c) typically illustrates the structure of a mother sheet. It is the schematic of the peeling method of the optical film which is this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st protective film 2 Optical film 3 2nd protective film 4 Punching blade type | mold 5 Press machine

Claims (4)

A first protective film; a plurality of optical films having a lens shape formed on one side thereof laminated on one side of the first protective film; and a side of the plurality of optical films facing the first protective film In the mother sheet | seat comprised with the 2nd protective film laminated | stacked on the opposite surface, the peeling method of the optical film which performs the next process in order of 1-3.
1. The mother sheet is curved so that the second protective film side is convex, and only the end of the optical film is peeled off at the interface between the first protective film and the optical film.
2. The second protective film is completely peeled from the optical film.
3. The first protective film is peeled off completely from the optical film.   The thickness of the first protective film is 60 to 150 μm, and the 180 ° peel strength between the first protective film and the optical film is 0.1 N / 25 mm or less. 2. The method for peeling an optical film according to claim 1, wherein the thickness is 30 to 150 μm, and the 180 ° peel strength between the second protective film and the optical film is 0.1 N / 25 mm or less.   The method for peeling an optical film according to claim 1 or 2, wherein the thickness of the optical film is 60 µm or less.   The method for peeling an optical film according to any one of claims 1 to 3, wherein the lens surface of the optical film has a prism shape.

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