JP2012030243A - Method for cutting polarizing plate, and polarizing plate cut by the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for cutting, in cutting a polarizing plate by using a laser light, a polarizing plate with no deformation in the cut surface, the polarizing plate including a film layer whose average rate of absorption of laser light in the emission wavelength range of the radiated laser light is 2% or less.SOLUTION: The method is provided for cutting a polarizing plate including a film layer whose average rate of absorption of laser light in the emission wavelength range of the radiated laser light is 2% or less. The method includes: a groove-forming step for forming a groove in the film by radiating a laser light having a regulated output and/or rate of traversing; and a tearing step for tearing the polarizing plate along the groove after the groove-forming step while regulating the tearing angle and the tension applied to the polarizing plate.

Description

  The present invention relates to a polarizing plate cutting method and a polarizing plate cut by the method. Specifically, the present invention relates to a method of cutting a polarizing plate including a film layer having an average absorption rate of laser light of 2% or less in the oscillation wavelength range of the irradiated laser light, and a polarizing plate cut by the method.

  In the field of using a polarizing plate, it is necessary to cut the polarizing plate to a desired length or size. When a long polarizing plate is cut using a cutting blade (for example, a round blade or a Thomson blade), there are the following problems.

  (1) By continuing to cut the polarizing plate, spilling (chipping) occurs on the cutting blade, or the cutting blade is worn. For this reason, in order to ensure a certain sharpness, it is necessary to periodically replace the cutting blade in which chipping or wear has occurred, resulting in an increase in running cost.

  (2) By cutting the polarizing plate, foreign matters such as film scraps and glue adhere to the cutting blade. As a result, the sharpness of the cutting blade is lowered and the cutting speed is changed.

  (3) When using a cutting blade, apply stress to cut the polarizing plate. For this reason, when the laminated polarizing plate to which the protective film is bonded is cut using a cutting blade, the end of the protective film is peeled off. Further, since the cut surface is easily cracked, the end of the laminated polarizing plate is easily cracked or broken. As a result, the durability of the laminated polarizing plate is reduced.

  Therefore, a method of cutting the polarizing plate by irradiating laser light has been proposed to solve the above-described problems caused by cutting the polarizing plate using a cutting blade.

  For example, Patent Document 1 describes that a polarizing plate can be cut by irradiating a laser beam. Specifically, a pair of triacetyl cellulose (TAC) films are bonded to both sides of a polyvinyl alcohol (PVA) film, and further, one TAC film side is covered with polyethylene terephthalate (PET) via an acrylic adhesive layer. ) A separator made of film is provided, and on the other TAC film side, a polarizing plate provided with a surface protective film made of PET film through an acrylic pressure-sensitive adhesive layer is cut by irradiating laser light. Yes. When the polarizing plate is cut by irradiating laser light, the problems (1) to (3) described above do not occur.

JP 2008-284572 A (released November 27, 2008)

  The polarizing plate which is a cutting target in Patent Document 1 is a film having an average absorption rate of laser light higher than 2% in the oscillation wavelength range of the irradiated laser light (hereinafter also referred to as “high absorption rate film”). It is laminated. A laminated polarizing plate made of such a high absorption rate film can be cut well by a conventional method as shown in Patent Document 1 without causing the cut surface of the polarizing plate to be deformed.

  However, in the conventional method as shown in Patent Document 1, a film having an average absorptance of laser light in the oscillation wavelength range of irradiated laser light of 2% or less (hereinafter also referred to as “low-absorbance film”). When a laminated polarizing plate including a layer (for example, a cycloolefin polymer film, a polypropylene film, a polymethyl methacrylate film, etc.) is cut, if the output of the laser beam is small, the high absorptivity film of the laminated polarizing plate Although the layer can be cut, the layer of the low absorptivity film cannot be cut. On the other hand, when the output of the laser beam is increased, it is possible to cut not only the layer of the high absorptivity film of the laminated polarizing plate but also the layer of the low absorptivity film. However, in this case, excessive heat is applied to the layer of the high absorptivity film, so that the end portion of the cut polarizing plate is melted and the cut end portion is deformed (see FIG. 6). A polarizing plate having a deformed cut surface has a reduced cross-sectional quality. Furthermore, various problems may occur due to the deterioration of the cross-sectional quality. For example, when a polarizing plate is bonded to a glass substrate, high adhesion is required. However, there is a problem that air bubbles are caught in the bonding surface with the glass substrate due to the unevenness of the cut surface of the polarizing plate.

  The present invention has been made in view of the above-mentioned conventional problems, and its main purpose is to obtain an average absorptance of laser light in the oscillation wavelength range of the irradiated laser light when the polarizing plate is cut using laser light. An object of the present invention is to provide a method of cutting a polarizing plate including a film layer having a thickness of 2% or less without causing deformation of the cut surface.

  In order to solve the above problems, the present invention is a method of cutting a polarizing plate including a film layer having an average absorption rate of laser light of 2% or less in the oscillation wavelength range of the irradiated laser light, By irradiating laser light with adjusted output and / or moving speed, a groove forming step for forming grooves in the film, and adjusting the tear angle and tension applied to the polarizing plate while adjusting the tension, A tearing step of tearing the polarizing plate after the groove forming step.

  In the method according to the present invention, in the groove forming step, the layer of the high absorptivity film is cut by laser light, and the groove is formed in the layer of the low absorptance film by laser light. And in the said tearing process, by applying force to the said groove | channel, a low absorptivity film is torn along a groove | channel and cut | disconnected. In the method according to the present invention, unlike the conventional laser cutting method, the output of the laser beam is increased so that the low absorption rate film is not cut by heat. Therefore, in the cutting of the polarizing plate using laser light, the polarizing plate including the layer of the low absorptivity film can be cut without causing deformation on the cut surface.

  In the method according to the present invention, it is preferable that grooves are formed on both surfaces of the film in the groove forming step.

  By forming grooves on both surfaces of the low absorptivity film in the groove forming step, the low absorptivity film can be efficiently torn in the subsequent tearing step.

  In the method according to the present invention, in the groove forming step, it is preferable that the output of the laser light is set in a range of 24 W to 77 W and the moving speed is set in a range of 300 mm / second to 1000 mm / second.

  If the output and moving speed of the laser beam in the groove forming step are the above values, the groove can be efficiently formed in the low absorptivity film of the polarizing plate.

  In the method according to the present invention, in the tearing step, it is preferable to set the tear angle of the polarizing plate to 10 ° or more and the tension to 0.1 N / mm or more.

  If the tear angle and tension in the tearing step are the above values, the low-absorbency film in which the groove is formed in the groove forming step can be torn and cut.

  In the method according to the present invention, the film may be a cycloolefin polymer film, a polypropylene film, or a polymethyl methacrylate film.

  In the method according to the present invention, in polarizing plate cutting using laser light, a polarizing plate including a layer of a low absorptivity film can be cut without causing deformation in the cut surface. Therefore, according to the method according to the present invention, even when the object to be cut is a polarizing plate including a layer of a cycloolefin polymer film, a polypropylene film, or a polymethyl methacrylate film as a low absorptivity film, The polarizing plate can be cut without causing deformation.

  In the method according to the present invention, the polarizing plate may be a polarizing plate including a film layer having an average absorption rate of laser light of 1% or less in the oscillation wavelength range of the irradiated laser light.

  In the method according to the present invention, even when the cutting target is a polarizing plate including a film layer having an average absorption rate of laser light of 1% or less in the oscillation wavelength range of the irradiated laser light, the cutting surface is deformed. It can cut | disconnect without producing.

  The polarizing plate according to the present invention is characterized by being cut by the above-described method according to the present invention.

  As described above, the method according to the present invention includes a film layer in which the average absorption rate of the laser beam in the oscillation wavelength range of the irradiated laser beam is 2% or less in the cutting of the polarizing plate using the laser beam. The polarizing plate can be cut without causing deformation on the cut surface. For this reason, the polarizing plate cut by the method according to the present invention has no deformation on the cut surface. Therefore, the polarizing plate according to the present invention can be a polarizing plate having high cross-sectional quality.

  As described above, the method according to the present invention is a method of cutting a polarizing plate including a film layer having an average absorption rate of laser light of 2% or less in the oscillation wavelength range of the irradiated laser light, and the output And / or a groove forming step for forming a groove in the film by irradiating a laser beam adjusted in moving speed, and adjusting the tear angle and tension applied to the polarizing plate while adjusting the groove along the groove. A tearing step of tearing the polarizing plate after the forming step.

  Moreover, the polarizing plate which concerns on this invention is a polarizing plate cut | disconnected by the method which concerns on this invention mentioned above.

  In the method according to the present invention, unlike the conventional laser cutting method, the layer of the low absorptivity film included in the polarizing plate is not cut by heat by increasing the output of the laser beam. Therefore, in cutting of a polarizing plate using laser light, a polarizing plate including a film layer having an average absorption rate of laser light of 2% or less in the oscillation wavelength range of the irradiated laser light is deformed on the cut surface. There exists an effect that it can cut, without making it occur. And the polarizing plate cut | disconnected by the method based on this invention has not produced the deformation | transformation in the cut surface. Therefore, the polarizing plate according to the present invention can be a polarizing plate having high cross-sectional quality.

It is a side view showing the composition of the outline of the slitter machine concerning this embodiment. It is a graph which shows the transmittance | permeability (%) in various films when the light of each wavelength is irradiated, (a) shows the transmittance | permeability (%) in a TAC film, a COP film, a PET film, and a PVA film, b) has shown the transmittance | permeability (%) in the TAC film (n-TAC) and PMMA film which provided phase difference performance. 2 is a side view showing a COP polarizing plate after being irradiated with laser light in Example 1. FIG. 3 is a side view showing the COP polarizing plate after the tearing process of Example 1. FIG. 1 is a front view showing a COP polarizing plate bonded to a glass substrate of Example 1. FIG. 6 is a side view showing a COP polarizing plate after laser light irradiation of Comparative Example 1. FIG. It is a front view which shows the COP polarizing plate bonded by the glass substrate of the comparative example 1. FIG. It is a graph which shows the relationship between the output of a laser beam and the moving speed on the conditions which can form a groove | channel in a COP polarizing plate.

  Hereinafter, an example of an embodiment according to the present invention will be described in detail. However, the present invention is not limited to this, and can be implemented in a mode in which various modifications are made within the described range. Moreover, all the academic literatures and patent literatures described in this specification are incorporated herein by reference. Unless otherwise specified in this specification, “A to B” indicating a numerical range means “A or more and B or less”.

[1. Method according to the present invention]
The method according to the present invention is a method of cutting a polarizing plate including a layer of a film (low absorptivity film) in which an average absorption rate of laser light in an oscillation wavelength range of irradiated laser light is 2% or less, By irradiating laser light with adjusted output and / or moving speed, a groove forming step for forming grooves in the film, and adjusting the tear angle and tension applied to the polarizing plate while adjusting the tension, A tearing step of tearing the polarizing plate after the groove forming step.

  Here, the “average absorption rate (%) of the laser beam in the oscillation wavelength range of the irradiated laser beam” can be measured using a conventionally known ATR (Attenuated total reflection) method. The “ATR method” refers to the absorption spectrum on the surface of the measurement target by irradiating the measurement target with light (laser light) having an arbitrary wavelength and measuring the light totally reflected on the surface of the measurement target. How to get. By measuring the absorptance of light having an arbitrary wavelength within the oscillation wavelength range of the irradiated laser light using the ATR method, and calculating the average value of the obtained absorptance, the “irradiated” The average absorption rate (%) of the laser beam in the oscillation wavelength range of the laser beam can be obtained.

  Examples of such a low absorption rate film include a cycloolefin polymer (COP) film, a polypropylene (PP) film, and a polymethyl methacrylate (PMMA) film.

  In the method according to the present invention, even when the cutting target is a polarizing plate including a film layer having an average absorption rate of laser light of 1% or less in the oscillation wavelength range of the irradiated laser light, the cutting surface is deformed. It can cut | disconnect without producing.

  A polarizing plate to be cut by the method according to the present invention (hereinafter, also referred to as “cutting target polarizing plate” or simply “cutting target”) includes a plurality of films including a low-absorption film as described above, and an adhesive. It is the polarizing plate laminated | stacked through the layer or the adhesive bond layer. That is, a polarizing plate including a layer of a high absorptivity film such as a polyethylene terephthalate (PET) film, a polyvinyl alcohol (PVA) film, or a triacetyl cellulose (TAC) film is intended in addition to the above-described low absorptivity film. Examples of such a polarizing plate include the COP polarizing plate used in Examples described later, but the present invention is not limited thereto.

  In addition, in the Example mentioned later, although the COP polarizing plate whose layer thickness of a COP film is 70 micrometers is used as a cutting object polarizing plate, the cutting object of the method which concerns on this invention is not limited to this. In the method according to the present invention, the groove can be formed in the low absorption film constituting the polarizing plate by adjusting the output and / or moving speed of the laser beam according to the thickness of the low absorption film. it can. Therefore, according to the method of the present invention, the polarizing plate can be cut regardless of the thickness of the low absorptivity film.

  The “groove forming step” and the “tear step” will be specifically described below.

(1) Groove forming step The groove forming step irradiates a laser beam with adjusted output and / or moving speed, thereby cutting the layer of the high absorptivity film constituting the polarizing plate with the laser beam, and And a step of forming grooves in the layer of the low absorptivity film by laser light. Here, “to form grooves in the film” means that the thickness of the film irradiated with the laser light is made thinner than the thickness of the other part, that is, the part irradiated with the laser light is so-called thin. It is pointing to the state of. More specifically, it refers to forming a groove of “U” shape or “V” shape as shown in FIG. In the groove forming step, it is only necessary to form a groove having such a depth that the portion irradiated with the laser beam is thin enough to tear the low absorptivity film by applying force in the subsequent tearing step. It is preferable to form a groove having a depth of 1/3 or more of the thickness of the low absorptivity film. By forming a groove having a depth of 1/3 or more of the thickness of the low absorptivity film, the low absorptivity film can be easily torn in the subsequent tearing step.

  In the polarizing plate shown in FIG. 3, grooves are formed on both surfaces of the COP film as a low absorption rate film. However, in the groove formation step, the grooves may be formed on at least one surface of the low absorption rate film. Further, in this specification, “output” of laser light refers to a numerical value represented by a unit “W”, for example. Further, the “moving speed” of the laser beam refers to a speed (speed) of moving the laser beam relative to the polarizing plate to be cut, and is expressed by a unit “mm / second”, for example. Point to a number.

  In the groove forming step, the output and / or moving speed of the laser light applied to the polarizing plate is such that a suitable groove can be formed in the layer of the low absorption rate film included in the polarizing plate to be cut. It can be adjusted appropriately. That is, both the output and moving speed of the laser light applied to the polarizing plate may be adjusted within the range in which grooves can be formed in the low absorptivity film, or only the output of the laser light may be adjusted. Alternatively, only the moving speed of the laser beam may be adjusted.

  Specifically, as shown in the examples described later, specifically, the output of the laser beam is appropriately adjusted according to the moving speed of the laser beam, or the moving speed of the laser beam is appropriately adjusted according to the output of the laser beam. By doing, a groove | channel can be formed in the low absorptivity film contained in the cutting object polarizing plate.

However, if the moving speed of the laser beam is too slow, the productivity is lowered. On the other hand, if the moving speed of the laser beam is too fast, it is necessary to increase the output of the laser beam. Therefore, for example, when a laser beam having an oscillation wavelength of 9.4 ± 0.2 μm is irradiated using a carbon dioxide laser (CO ₂ laser), the output of the laser beam is in the range of 24 W to 77 W, and In the range of 300 mm / sec to 1000 mm / sec, the moving speed of the laser beam is adjusted to the output and / or moving speed to efficiently groove the low absorptivity film included in the polarizing plate to be cut. Can be formed.

  The moving speed of the laser light may be adjusted by changing the speed of moving the cutting target polarizing plate relative to the laser light irradiation apparatus. You may adjust by changing the speed which moves relatively.

The laser beam can be irradiated using a conventionally known laser irradiation apparatus. Specifically, for example, a CO ₂ laser.

  Laser light irradiation conditions other than the moving speed and output of the laser light can also be set as needed. For example, the groove width can be controlled by adjusting the spot diameter of the laser beam. The spot diameter of the laser beam is usually 40 μm to 50 μm.

Further, the wavelength of the laser beam to be irradiated can be appropriately selected according to the type of the laser irradiation apparatus. In the examples described later, a CO ₂ laser is used to irradiate laser light having an oscillation wavelength of 9.4 ± 0.2 μm. However, the present invention is not limited to this. However, from the viewpoint of efficiently forming grooves in the low absorptivity film contained in the polarizing plate to be cut, a high absorptivity film other than the low absorptive film contained in the polarizing plate to be cut (for example, a PET film, (PVA film, TAC film, etc.) It is preferable to irradiate laser light having an oscillation wavelength that increases the absorption rate. For example, a CO ₂ laser can irradiate laser light having a wavelength of around 10 μm, but as shown in FIG. 2, the absorption rate of laser light in various films varies depending on the wavelength of the irradiated light. For this reason, from the viewpoint of further increasing the absorptance of laser light in the high absorptivity film, when using a CO ₂ laser, it is preferable to irradiate laser light having an oscillation wavelength of 9.2 μm to 10.8 μm.

  The length from the upper surface of the cutting target polarizing plate on the side irradiated with laser light to the focal point of the laser light (hereinafter also referred to as “focal length”) is not particularly limited, but is included in the cutting target polarizing plate. From the viewpoint of efficiently forming grooves in the low absorptivity film, the “focal length” is equal to or greater than the thickness from the upper surface of the polarizing plate to be cut to the laser light irradiation side to the upper surface of the layer of the low absorptivity film. And it is preferable to adjust the laser light irradiation conditions so that the thickness from the upper surface on the laser light irradiation side of the polarizing plate to be cut to the lower surface of the layer of the low absorptivity film is less than or equal to .

  In the groove forming step, the groove can be formed in the low absorptivity film included in the cutting target polarizing plate, regardless of which side of the surface of the cutting target polarizing plate is irradiated with the laser beam. In the examples described later, the grooves are formed in the low absorptivity film (CPO film) included in the polarizing plate by irradiating laser light from the protective film side of the polarizing plate. Also when the laser beam is irradiated from the above, grooves can be formed in the low absorptivity film contained in the polarizing plate.

(2) Tear process A tear process is a process of tearing the low absorption rate film after a groove formation process along the groove | channel formed in the groove formation process, adjusting the tear angle and the tension | tensile_strength given to a cutting object polarizing plate.

  In one embodiment, the cutting target polarizing plate after the groove forming step can be torn using a slitter machine in which the tear angle and the tension applied to the cutting target polarizing plate are adjusted. Below, the method using a slitter machine is demonstrated based on FIG. 1 as an example of the method of tearing the polarizing plate to be cut | disconnected. FIG. 1 is a side view showing a schematic configuration of a slitter machine 5 according to the present embodiment, and shows a state where a polarizing plate (a polarizing plate to be cut) 3 is being wound up. The arrows in FIG. 1 indicate the tearing direction of the polarizing plate 3.

  The slitter machine 5 includes a conveying roller 1 (1a, 1b, 1c and 1d) and a winding shaft 2 (2a and 2b).

  The polarizing plate 3 after the groove forming step is introduced into the slitter machine 5 so that the tearing direction (groove forming direction) of the polarizing plate 3 and the conveying direction of the polarizing plate 3 are parallel to each other, and the conveying rollers 1 (1a, 1b, 1c and 1d). Then, one polarizing plate is wound around the winding shaft 2a with respect to the groove formed in the polarizing plate 3, and the other polarizing plate is wound around the winding shaft 2b, so that the polarizing plate 3 follows the groove. Torn.

  In the slitter machine 5 shown in FIG. 1, the winding shafts 2a and 2b are arranged so as to form a predetermined tear angle so that the polarizing plate 3 can be torn, and the winding tension becomes a predetermined value. Have been adjusted so that. Here, in the present specification, the above “tear angle” refers to an angle α formed by one tear side A of the polarizing plate 3 and the other tear side B. The “corner apex C” is the tear point of the polarizing plate 3. The “tension” refers to the tension applied to the polarizing plate 3 in a direction parallel to the tear direction.

  In the tearing step, the “tear angle” and the “tension” are not particularly limited as long as the polarizing plate 3 can be torn along the groove, but the “tear angle” is 10 ° or more, and the “tension” "Is 0.1 N / mm or more, the polarizing plate can be torn well. The greater the “tear angle”, the greater the shear stress, and the easier it is to tear the polarizing plate. For this reason, it is preferable that the “tear angle” is 30 ° or more.

  The transport rollers 1 (1a, 1b, 1c, and 1d) are disposed along the transport path of the polarizing plate 3, and the transport rollers 1a are disposed so as to press the polarizing plate 3 against the transport rollers 1b. The conveyance roller 1 and the winding shaft 2 are not particularly limited, and known ones can be used.

  In the method according to the present invention, a cutting blade (for example, a round blade or a Thomson blade conventionally used in this field) may be used in combination as necessary. For example, in the groove forming step, after the grooves are formed in the low absorption rate film by laser light irradiation, the groove portions may be cut using a cutting blade.

[2. Polarizing plate according to the present invention]
The polarizing plate according to the present invention is characterized by being cut by the method according to the present invention. The method according to the present invention has been described in the above section “1. Method according to the present invention”, and is therefore omitted here.

  As described above, in the method according to the present invention, in polarizing plate cutting using laser light, a polarizing plate including a layer of a low absorptivity film can be cut without causing deformation of the cut surface. . For this reason, the polarizing plate cut by the method according to the present invention has no deformation on the cut surface. Therefore, the polarizing plate according to the present invention can be a polarizing plate having high cross-sectional quality.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these examples.

(Measurement of absorption rate in various films)
The transmittance (%) in various films was measured by a conventionally known ATR method. Since the “ATR method” has been described in the above section “1. Method according to the present invention”, the description thereof is omitted here.

  The results are shown in FIG. FIG. 2 is a graph showing transmittance (%) in various films when irradiated with light of each wavelength. (A) of FIG. 2 shows the transmittance (%) in a TAC film, a COP film, a PET film, and a PVA film, and (b) of FIG. 2 shows a TAC film (n-TAC) imparted with retardation performance, It is a graph which shows the transmittance | permeability (%) in a PMMA film. The n-TAC film is a film in which contrast performance is improved by substituting a part of TAC acetate with propionate, adding an additive, and stretching.

Table 1 shows the results of calculating the average transmittance and average absorptance of each film in the range of the oscillation wavelength of the CO ₂ laser (9.2 μm to 10.8 μm). The average absorption rate (%) was obtained by subtracting the average transmittance (%) from 100%.

As shown in Table 1, in the CO ₂ laser oscillation wavelength range (9.2 μm to 10.8 μm), the TAC film, the n-TAC film, the PVA film, and the PET film have a laser light absorption rate of 2%. It was confirmed that it was higher. On the other hand, it was confirmed that the COP film and the PMMA film have a laser light absorption rate of 2% or less.

[Example 1]
As a cutting target, a cycloolefin polymer (COP) polarizing plate (SRD341 mass production raw material) was used. From the top, the COP polarizing plate is a PET film (58 μm), a TAC film (80 μm) as a protective film, a PVA film (25 μm) as a polarizer, a COP film (70 μm), an adhesive layer (25 μm), and a separate film. The PET film (38 μm) is laminated.

(Groove formation process)
In the groove forming process of Example 1, a laser beam irradiation device (CO ₂ laser, model number: Diamond E-400i, manufacturer: manufactured by Coherent, USA) was used, and the moving speed was adjusted to 300 mm / second and the output was adjusted to 25 W. By irradiating the COP polarizing plate with light (oscillation wavelength: 9.4 ± 0.2 μm), the TAC film layer, the PVA film layer, the adhesive layer and the PET film layer constituting the COP polarizing plate are cut, Grooves were formed in the COP film layer. Other laser light irradiation conditions are as shown in Table 2. The “focal point” shown in Table 2 represents the length from the upper surface of the protective film layer to the focal point of the laser beam.

  The COP polarizing plate after laser light irradiation is shown in FIG. The COP polarizing plate of FIG. 3 is shown such that the width direction is the horizontal direction, and the cut surface is located at the center. As shown in FIG. 3, the protective film layer 6 (PET film layer), TAC film layer 7, PVA film layer 8, pressure-sensitive adhesive layer 10 and separate film layer 11 (PET film layer) of the COP polarizing plate It was cut by irradiation. On the other hand, the COP film layer 9 has grooves formed on the upper and lower surfaces of the film. The groove formed on the upper surface of the COP film layer 9 had a depth of 22 μm, and the groove formed on the lower surface of the COP film layer 9 had a depth of 22 μm.

(Tear process)
Next, using the slitter machine 5 shown in FIG. 1, the COP polarizing plate after the groove forming step as the polarizing plate 3 was torn. Specifically, the COP polarizing plate after the groove forming step was introduced into the slitter machine 5 and adjusted so that the tear angle α of the COP polarizing plate was 40 ° and the tension applied to the COP polarizing plate was 0.6 N / mm. While winding the COP polarizing plate with the winding shafts 2a and 2b, the COP polarizing plate was torn.

  The COP polarizing plate after the tearing process is shown in FIG. The COP polarizing plate of FIG. 4 is shown such that the width direction is the horizontal direction, and the cut surface is located on the right side. As shown in FIG. 4, no deformation was observed in the cut end portion of the COP film layer 9 on the cut surface (cut end portion) of the COP polarizing plate.

  Furthermore, the state which peeled the separate film from the cut | disconnected COP polarizing plate, and bonded the COP polarizing plate to the glass substrate is shown in FIG. FIG. 5 is a front view showing a COP polarizing plate bonded to a glass substrate. In FIG. 5, the bonding surface is observed at a magnification of 50 times. The glass substrate is arrange | positioned in the figure lower side, and the COP polarizing plate is bonded through the 25-micrometer adhesive layer. As shown in FIG. 5, the COP polarizing plate of Example 1 and the glass substrate were bonded together in a state where air bubbles were not caught. This is considered to be because the cutting end portion was not deformed and the flat state was maintained when the COP polarizing plate in Example 1 was cut.

[Comparative Example 1]
In Comparative Example 1, the COP polarizing plate used in Example 1 was used as a cutting target. Except for completely cutting the COP polarizing plate by irradiating the COP polarizing plate with laser light (oscillation wavelength: 9.4 ± 0.2 μm) adjusted to a moving speed of 300 mm / second and an output of 45 W. The same laser light irradiation conditions as in Example 1 were used.

  The COP polarizing plate after laser beam irradiation is shown in FIG. The COP polarizing plate of FIG. 6 is shown such that the width direction is the horizontal direction, and the cut surface is located on the left side. When the COP polarizing plate was cut only by laser light irradiation as in Comparative Example 1, the COP film layer 9 of the COP polarizing plate was deformed by the influence of heat, as shown in FIG.

  Furthermore, the state which peeled the separate film from the cut | disconnected COP polarizing plate and bonded the COP polarizing plate to the glass substrate similarly to Example 1 is shown in FIG. FIG. 7 is a front view showing a COP polarizing plate bonded to a glass substrate. The glass substrate is arrange | positioned at the lower side in the figure, and the COP polarizing plate is bonded through the adhesive layer. 7 and 5 observe the bonding surface at the same magnification (magnification 50 times).

  As shown in FIG. 7, the COP polarizing plate of Comparative Example 1 and the glass substrate were bonded in a state where air bubbles were bitten. This is presumably because the COP film layer was deformed by the influence of heat when the COP polarizing plate was cut in Comparative Example 1, and the cut end portion was deformed.

  From the result of the cut COP polarizing plate in Example 1 and Comparative Example 1, even if it is a polarizing plate including a layer of a low absorptivity film, the cut surface is deformed by using the method according to the present invention. It was confirmed that it could be cut without causing it.

[Example 2]
FIG. 8 shows the relationship between the laser beam output and the moving speed under conditions that allow grooves to be formed in the COP polarizing plate. The graph of FIG. 8 shows the output range (upper limit and lower limit) of the laser beam with respect to the moving speed of the laser beam. The same COP polarizing plate as in Example 1 was used, and the laser beam irradiation conditions other than the laser beam output and moving speed were the same as those in Example 1.

  As shown in FIG. 8, even when the moving speed of the laser beam is changed, the groove is formed in the COP film layer constituting the COP polarizing plate by adjusting the output of the laser beam. I was able to confirm that In other words, the polarizing plate is configured by appropriately adjusting the output of the laser light according to the moving speed of the laser light or by appropriately adjusting the moving speed of the laser light according to the output of the laser light. It can be said that it was confirmed that grooves could be formed in the low-absorption rate film. Thus, the COP polarizing plate in which the groove is formed in the low-absorption coefficient film by adjusting the output and / or moving speed of the laser light is torn in the tearing process, so that the COP is not deformed on the cut surface. The polarizing plate can be cut.

  According to the method of the present invention, even a polarizing plate including a film layer having an average absorption rate of laser light of 2% or less in the oscillation wavelength range of the irradiated laser light is deformed on the cut surface. It can be cut without causing it to occur. For this reason, this invention can be utilized suitably in the field | area which uses a polarizing plate.

DESCRIPTION OF SYMBOLS 1 Conveyance roller 1a Conveyance roller 1b Conveyance roller 1c Conveyance roller 1d Conveyance roller 2 Winding shaft 2a Winding shaft 2b Winding shaft 3 Polarizing plate 5 Slitting machine 6 Protective film layer (PET film layer)
7 TAC film layer 8 PVA film layer 9 COP film layer 10 Adhesive layer 11 Separate film layer (PET film layer)
A Tear edge B Tear edge C Angle vertex α Tear angle

Claims (7)

A method of cutting a polarizing plate including a film layer having an average absorption rate of laser light of 2% or less in the oscillation wavelength range of the irradiated laser light,
A groove forming step of forming grooves in the film by irradiating laser light with adjusted output and / or moving speed;
While adjusting the tear angle and the tension applied to the polarizing plate, tearing the polarizing plate after the groove forming step along the groove,
A method comprising the steps of:   The method according to claim 1, wherein in the groove forming step, grooves are formed on both surfaces of the film.   3. The method according to claim 1, wherein in the groove forming step, an output of laser light is set in a range of 24 W to 77 W, and a moving speed is set in a range of 300 mm / second to 1000 mm / second.   The method according to any one of claims 1 to 3, wherein, in the tearing step, the tear angle of the polarizing plate is set to 10 ° or more and the tension is set to 0.1 N / mm or more.   The method according to claim 1, wherein the film is a cycloolefin polymer film, a polypropylene film, or a polymethyl methacrylate film.   6. The polarizing plate according to claim 1, wherein the polarizing plate includes a film layer having an average absorption rate of laser light of 1% or less in an oscillation wavelength range of the irradiated laser light. The method according to item.   The polarizing plate cut | disconnected by the method of any one of Claims 1-6.