JP2013164935A - Laminate cutting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate cutting method which is less likely to cause destruction of a barrier layer formed using an inorganic material.SOLUTION: A laminate cutting method comprises: a first step of arranging a laminate having a substrate formed using a resin material and a barrier layer formed so as to protect the substrate using an inorganic material; and a second step of cutting the laminate using a cutting die having a cutting blade. In the second step, the cutting blade enters the barrier layer and then enters the substrate.

Description

  The present invention relates to a cutting method for cutting a substrate having a laminated structure used in a display device such as an organic EL display device.

  A display device such as an organic EL display device is formed using a laminate including a substrate and a barrier layer that protects the substrate. A TFT device and an EL device for displaying an image are formed on the substrate. The barrier layer prevents deterioration of elements (TFT devices and EL devices) on the substrate. In many cases, the barrier layer contains an inorganic material and has a low water vapor transmission rate. As a result, the elements on the substrate are appropriately protected from water vapor.

  The laminate including the substrate and the barrier layer is cut into a predetermined shape. As a cutting method, punching is known (for example, Patent Documents 1 to 3).

JP 2011-5627 A JP 2002-11697 A JP 2004-154913 A

  As described above, since the barrier layer contains an inorganic material, if the laminate is cut using the above-described known punching technique, the barrier layer is easily brittlely broken. As a result of the brittle fracture of the barrier layer, peeled pieces generated from the barrier layer come into contact with elements on the substrate, causing an electrical failure of the display device. Further, water vapor enters from cracks generated in the barrier layer, and the deterioration of the elements on the substrate is promoted.

  An object of this invention is to provide the cutting method of the laminated body which does not cause destruction of the barrier layer formed using the inorganic material.

  A method for cutting a laminate according to one aspect of the present invention includes: a laminate having a substrate formed using a resin material; and a barrier layer formed using an inorganic material so as to protect the substrate. A first step of disposing, and a second step of cutting the laminate using a punching die having a cutting blade, wherein in the second step, the cutting blade enters the barrier layer And entering the substrate.

  The method for cutting a laminate according to the present invention can appropriately cut the laminate without substantially destroying the barrier layer.

It is a schematic flowchart showing the cutting method of a laminated body. It is a schematic sectional drawing of the laminated body produced in step S100 of the flowchart shown by FIG. It is the schematic of step S200 of the flowchart shown by FIG. It is the schematic of step S300 of the flowchart shown by FIG. It is the schematic of step S300 of the flowchart shown by FIG. It is the schematic of step S300 of the flowchart shown by FIG. It is a microscope picture around the cutting edge of the barrier layer of the laminated body cut | disconnected using the Thomson type | mold. FIG. 5B is a schematic trace diagram of the micrograph of FIG. 5A. It is a microscope picture around the cutting edge of the barrier layer of the laminated body cut | disconnected using the cutter. FIG. 6B is a schematic trace diagram of the micrograph of FIG. 6A. It is a microscope picture around the cutting edge of the barrier layer of the laminated body cut | disconnected using the scissors. It is a schematic trace figure of the micrograph of FIG. 7A. 4 shows a Thomson-type punching direction according to the cutting method shown in FIGS. 4A to 4C. It is a schematic sectional drawing of the laminated body punched in the direction opposite to the punching direction shown by FIG. 8A. It is a microscope picture around the cutting edge of the barrier layer obtained on the conditions shown by FIG. 8A. It is a schematic trace figure of the micrograph of FIG. 9A. It is a microscope picture around the cutting edge of the barrier layer obtained on the conditions shown by FIG. 8B. FIG. 10B is a schematic trace diagram of the micrograph of FIG. 10A. It is the schematic of a Thomson type cutting blade. It is the schematic of a Thomson type cutting blade. It is the schematic of a Thomson type cutting blade. It is the schematic of a Thomson type cutting blade. It is a microscope picture around the cutting edge of the barrier layer of the laminated body cut | disconnected using the cutting blade shown by FIG. 11A. It is a microscope picture around the cutting edge of the barrier layer of the laminated body cut | disconnected using the cutting blade shown by FIG. 11B. It is a microscope picture around the cutting edge of the barrier layer of the laminated body cut | disconnected using the cutting blade shown by FIG. 11C. It is a microscope picture around the cutting edge of the barrier layer of the laminated body cut | disconnected using the cutting blade shown by FIG. 11D. It is a schematic trace figure of the micrograph of FIG. 12A. FIG. 12B is a schematic trace diagram of the micrograph of FIG. 12B. 12D is a schematic trace diagram of the micrograph of FIG. 12C. FIG. FIG. 12D is a schematic trace diagram of the micrograph of FIG. 12D. It is a schematic sectional drawing of the other laminated body produced in step S100 of the flowchart shown by FIG. It is the schematic of step S200 of the flowchart shown by FIG. It is the schematic of step S300 of the flowchart shown by FIG. It is the schematic of step S300 of the flowchart shown by FIG. It is the schematic of step S300 of the flowchart shown by FIG. It is the schematic of step S300 of the flowchart shown by FIG.

  Hereinafter, the cutting method of a laminated body is demonstrated with reference to drawings. In the embodiment described below, the same reference numerals are given to the same components. For the sake of clarification of explanation, duplicate explanation is omitted as necessary. The structure, arrangement, or shape shown in the drawings and the description related to the drawings are intended to facilitate understanding of the principle of the method of cutting the laminate. Therefore, the principle of the method for cutting the laminate is not limited to these.

(Laminate cutting method)
FIG. 1 is a schematic flowchart showing a method for cutting a laminate. The method for cutting the laminate will be described with reference to FIG. Note that terms used in the following description to express directions such as “up” and “down” are for clarifying the principle of the present embodiment. Therefore, the principle of this embodiment is not limited to these terms.

(Step S100)
In step S100, a substrate formed using a resin material such as polyimide is prepared. Elements necessary for displaying an image such as a TFT device or an EL device are formed on the upper surface of the substrate. The substrate prepared in step S100 may have flexibility. In this case, the laminated body created in step S100 is used as a flexible substrate.

  In addition to polyimide, materials that can be used as flexible substrates include polyamideimide, polyimide benzoxazole, copolymers containing polyimide as a unit structure in addition to polyimide benzimidazole, polybenzoxazole, polyester, polytetrafluoroethylene, polyphenylene Polyolefin such as sulfide, polyamide, polycarbonate, polystyrene, polypropylene, polyethylene, polyvinyl chloride, polyethersulfone, polyethylene naphthalene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, cyclic polyolefin, modified polyolefin, polyvinyl chloride , Polyvinylidene chloride, acrylic resin, polymethyl methacrylate, acrylic-styrene copolymer, butadiene-styrene Polymer, ethylene-vinyl alcohol copolymer, polyether, polyetherketone, polyetheretherketone, polyetherimide, polyacetal, polyphenylene oxide, modified polyphenylene oxide, polyarylate, aromatic polyester, polytetrafluoroethylene, polyfluoride Examples include vinylidene. Moreover, the multilayer structure which combined 1 type (s) or 2 or more types among these materials may be sufficient.

  In step S100, a barrier layer is formed on the upper surface of the substrate using an inorganic material such as SiON. The barrier layer may be formed by a known method. Since the barrier layer contains an inorganic material, it has a low water vapor transmission rate. Therefore, the element on the upper surface of the substrate covered with the barrier layer is appropriately protected by the barrier layer from water vapor and other factors that degrade the performance of the element.

  In addition to silicon oxide (SiOx), silicon nitride (SiN) and mixtures thereof (SiON), inorganic materials that can be used as the barrier layer include at least Al, Ti, Zr, Ge, Ca, and Mg. An oxide or a nitride containing one as a constituent element can be given.

  As described above, the barrier layer contains an inorganic material. Therefore, the barrier layer is more susceptible to brittle fracture than a substrate formed using a resin material.

  Formation of the barrier layer on the upper surface of the substrate completes the stack. Thereafter, step S200 is executed.

(Step S200)
In step S200, the laminate is disposed below the Thomson type having a cutting blade. The laminated body may be appropriately fixed using, for example, a jig below the Thomson type. When the arrangement of the stacked bodies is completed, step S300 is executed. In the present embodiment, step S200 is exemplified as the first step.

(Step S300)
In step S300, the laminate is punched using a Thomson mold. As a result, the laminate is cut into a desired shape. In the present embodiment, the Thomson type is exemplified as a punching type. Alternatively, the punching die may be another die that can punch the laminate into a desired shape. Step S300 of this embodiment is illustrated as a 2nd process.

  FIG. 2 is a schematic cross-sectional view of the laminate 100 created in step S100 described with reference to FIG. The laminated body 100 is demonstrated using FIG.1 and FIG.2.

  In the present embodiment, a substrate 110 formed using polyimide is prepared. As described above, various elements (for example, a TFT device and an EL device) necessary for displaying an image are formed on the upper surface of the substrate 110. The substrate 110 has a thickness of 20 μm or more and 50 μm or less. In the present embodiment, the substrate 110 has a thickness of about 40 μm.

  In this embodiment, the barrier layer 120 is formed on the upper surface of the substrate 110 using SiON. The barrier layer 120 covers the above-described element formed on the upper surface of the substrate 110. As a result, the elements on the substrate 110 are appropriately protected from water vapor by the barrier layer 120. The barrier layer 120 has a thickness of 0.1 μm or more and 1 μm or less. In this embodiment, the barrier layer 120 has a thickness of about 1 μm.

  FIG. 3 is a schematic diagram of step S200 described with reference to FIG. Step S200 will be further described with reference to FIGS.

  As described above, in step S200, the stacked body 100 is disposed below the Thomson mold 200. The barrier layer 120 of the stacked body 100 faces the Thomson type 200.

  4A to 4C are schematic views of step S300 described with reference to FIG. Step S300 is further described with reference to FIGS. 1, 3 to 4C.

  3 to 4C schematically show a Thomson-type 200 cutting blade. As shown in FIGS. 3 to 4C, the Thomson die 200 has double-edged blades used as cutting blades. As shown in FIGS. 4A to 4C, the cutting blade of the Thomson die 200 is pushed into the laminate 100 in step S300.

  When step S300 is started, the Thomson die 200 descends and the cutting blade approaches the laminate 100 (see FIGS. 3 and 4A). As a result, as shown in FIG. 4A, the Thomson-type 200 cutting blade first enters the barrier layer 120.

  As shown in FIG. 4B, the Thomson die 200 is then further lowered, and the cutting blade of the Thomson die 200 enters the substrate 110. As shown in FIG. 4C, the cutting blade of the Thomson die 200 finally reaches the lower surface of the substrate 110. As a result, the laminate 100 is cut into a desired shape.

(Relationship between cutting method and barrier layer destruction)
This inventor cut | disconnected the laminated body using the Thomson type | mold, the cutter, and the scissors, and investigated the relationship between the cutting | disconnection system and destruction of a barrier layer. FIG. 5A is a photomicrograph around the cutting edge of the barrier layer of the laminate cut using the Thomson mold. FIG. 5B is a schematic trace of the micrograph of FIG. 5A. FIG. 6A is a photomicrograph around the cutting edge of the barrier layer of the laminate cut with a cutter. FIG. 6B is a schematic trace of the micrograph of FIG. 6A. FIG. 7A is a photomicrograph around the cutting edge of the barrier layer of the laminate cut with a scissors. FIG. 7B is a schematic trace of the micrograph of FIG. 7A. The relationship between the cutting method and the destruction of the barrier layer will be described with reference to FIGS. 4A to 7B.

  As shown in FIGS. 5A and 5B, cracks or delamination on the surface of the barrier layer of the laminate cut using the Thomson mold according to the cutting method described with reference to FIGS. 4A to 4C. Was hardly observed.

  As shown in FIG. 6A and FIG. 6B, a large number of cracks were observed around the cut edge of the barrier layer of the laminate cut with the cutter.

  As shown in FIGS. 7A and 7B, a large number of cracks were observed around the cut edge of the barrier layer of the laminate cut with the scissors.

  From the observation results on the surface of the barrier layer described above, it can be seen that the punching can minimize damage to the barrier layer of the laminate.

  This inventor measured the magnitude | size of the piece peeled from the barrier layer, and the distance from a cutting edge to the front-end | tip of a crack using the microscope picture. The table shown below represents the measurement results.

  Fragments having a size of 0 μm or more and less than 25 μm were observed in the micrographs around the cutting edge of the laminate cut using the scissors and the Thomson mold. On the other hand, fragments having a size of 25 μm or more were observed in the micrograph around the cutting edge of the laminate cut with the cutter. From the viewpoint of the size of the peeled piece, as a method for cutting the laminate, cutting using a Thomson type or scissors is more preferable than cutting using a cutter.

  A crack having a length of 150 μm or more was observed in a micrograph around the cutting edge of the laminate cut with the scissors and the cutter. On the other hand, the length of the crack observed in the micrograph around the cutting edge of the laminate cut using the Thomson mold was 0 μm or more and less than 150 μm. From the viewpoint of the length of cracks, as a method for cutting a laminate, cutting using a Thomson mold is more preferable than cutting using a scissors and a cutter.

(Relationship between punching direction and barrier layer destruction)
The inventor investigated the relationship between the Thomson-type punching direction and the barrier layer destruction.

  FIG. 8A shows the punching direction of the Thomson mold 200 according to the cutting method described with reference to FIGS. 4A to 4C. In the following description, the punching direction shown in FIG. 8A is referred to as a first direction.

  FIG. 8B is a schematic cross-sectional view of the laminated body 100 punched in the second direction opposite to the first direction by the Thomson mold 200. When the laminate 100 is punched in the second direction, the cutting blade of the Thomson die 200 enters the substrate 110 and then enters the barrier layer 120.

  FIG. 9A is a photomicrograph around the cutting edge of the barrier layer 120 obtained by punching in the first direction. FIG. 9B is a schematic trace of the micrograph of FIG. 9A. FIG. 10A is a photomicrograph around the cutting edge of the barrier layer 120 obtained by punching in the second direction. FIG. 10B is a schematic trace of the micrograph of FIG. 10A. The relationship between the punching direction and the breakage of the barrier layer 120 will be described with reference to FIGS. 8A to 10B.

  Referring to FIGS. 9A and 9B, it can be seen that if the stacked body 100 is punched in the first direction, the barrier layer 120 is hardly destroyed. On the other hand, referring to FIGS. 10A and 10B, it can be seen that if the laminate 100 is punched in the second direction, a number of cracks and delaminations occur in the barrier layer 120.

  As shown in FIG. 8A, if the laminate 100 is punched in the first direction, the force applied to the barrier layer 120 by the cutting blade of the Thomson die 200 acts as a compressive force on the boundary between the barrier layer 120 and the substrate 110. . On the other hand, as shown in FIG. 8B, if the laminate 100 is punched in the second direction, the force applied to the barrier layer 120 by the cutting blade of the Thomson die 200 acts to peel off the barrier layer 120 from the substrate 110. . As a result, it is considered that punching of the laminate 100 in the second direction causes cracking and peeling of the barrier layer 120.

(Relationship between cutting blade shape and barrier layer destruction)
11A to 11D schematically show the cutting blades 211, 212, 213, and 214 of the Thomson die 200, respectively. This inventor cut | disconnected the laminated body using the cutting blade 211,212,213,214, and investigated the relationship between the shape of a cutting blade, and destruction of a barrier layer.

  The cutting edge angle of the cutting blade 211 is 30 °. The cutting blade 211 is mirror-polished.

  Similar to the cutting blade 211, the cutting edge angle of the cutting blade 212 is 30 °. Unlike the cutting blade 211, the cutting blade 212 is not mirror-polished.

  Unlike the cutting blades 211 and 212, the cutting edge angle of the cutting blade 213 is 43 °. Similar to the cutting blade 211, the cutting blade 213 is mirror-polished.

  Similar to the cutting blade 213, the cutting edge angle of the cutting blade 214 is 43 °. Like the cutting blade 212, the cutting blade 214 is not mirror-polished.

  FIG. 12A is a photomicrograph around the cutting edge of the barrier layer of the laminate cut with the cutting blade 211. FIG. 13A is a schematic trace of the micrograph of FIG. 12A.

  FIG. 12B is a photomicrograph around the cutting edge of the barrier layer of the laminate cut with the cutting blade 212. FIG. 13B is a schematic trace of the micrograph of FIG. 12B.

  FIG. 12C is a photomicrograph around the cutting edge of the barrier layer of the laminate cut with the cutting blade 213. FIG. 13C is a schematic trace of the micrograph of FIG. 12C.

  FIG. 12D is a photomicrograph around the cutting edge of the barrier layer of the laminate cut with the cutting blade 214. FIG. 13D is a schematic trace of the micrograph of FIG. 12D.

  In the micrograph around the cutting edge of the barrier layer cut using the cutting blades 211 and 212, peeling of the barrier layer was not confirmed. On the other hand, in the micrograph around the cutting edge of the barrier layer cut using the cutting blades 213 and 214, a fragment peeled from the barrier layer was confirmed. The fragments generated from the barrier layer cut using the cutting blade 214 were larger than the fragments generated from the barrier layer cut using the cutting blade 213.

  From the above observation results, it can be seen that if a double-edged blade having a cutting edge angle of 30 ° or less is used as the cutting blade, the barrier layer is not easily destroyed. Moreover, it turns out that the mirror-polished cutting blade is hard to destroy a barrier layer.

(Structure of other laminates)
FIG. 14 is a schematic cross-sectional view of another stacked body 100A created in step S100 described with reference to FIG. The laminated body 100A will be described with reference to FIGS.

  Similar to the stacked body 100 described with reference to FIG. 2, the stacked body 100 </ b> A includes a substrate 110 and a barrier layer 120 that covers the upper surface of the substrate 110. The stacked body 100 </ b> A further includes a first protective layer 130 that covers the upper surface of the barrier layer 120, and a second protective layer 140 that covers the lower surface of the substrate 110.

  The materials and thicknesses of the first protective layer 130 and the second protective layer 140 are appropriately determined according to the barrier layer 120 and the substrate 110. In the present embodiment, the first protective layer 130 and the second protective layer 140 are formed using PET having a thickness of about 75 μm.

  FIG. 15 is a schematic diagram of step S200 described with reference to FIG. Step S200 will be described with reference to FIGS.

  In step S <b> 200, the stacked body 100 </ b> A is disposed below the Thomson mold 200. The first protective layer 130 of the stacked body 100 </ b> A faces the Thomson type 200.

  16A to 16D are schematic views of step S300 described with reference to FIG. Step S300 will be described with reference to FIGS. 1 and 15 to 16D.

  15 to 16D schematically show a cutting blade of a Thomson type 200. FIG. As shown in FIGS. 15 to 16D, the Thomson die 200 has double-edged blades used as cutting blades. As shown in FIGS. 16A to 16D, in step S300, the cutting blade of the Thomson die 200 is pushed into the laminate 100A.

  When step S300 is started, the Thomson die 200 is lowered and the cutting blade approaches the laminate 100A (see FIGS. 15 and 16A). As a result, as shown in FIG. 16A, the Thomson-type 200 cutting blade first enters the first protective layer 130.

  As shown in FIG. 16B, the Thomson die 200 is then further lowered, and the cutting blade of the Thomson die 200 enters the barrier layer 120.

  As shown in FIG. 16C, the Thomson die 200 is then further lowered, and the cutting blade of the Thomson die 200 enters the substrate 110.

  As shown in FIG. 16D, the Thomson die 200 is further lowered, and the cutting blade of the Thomson die 200 enters the second protective layer 140. The cutting blade of the Thomson mold 200 finally reaches the lower surface of the second protective layer 140. As a result, the laminated body 100A is cut into a desired shape.

(Effect of protective layer)
The inventor created the laminates 100 and 100A, and cut the laminates 100 and 100A using a Thomson mold. This inventor observed the damage of the barrier layer around the cutting edge of the laminated bodies 100 and 100A using a micrograph. In addition, the present inventor measured the size of the piece peeled from the barrier layer and the distance from the cutting edge to the tip of the crack. The table shown below represents the measurement results.

  No significant difference was found regarding the length of the crack between the laminates 100 and 100A. However, peeling pieces were observed in the laminate 100, whereas no peeling pieces were observed in the laminate 100A. Therefore, it can be seen that the first protective layer 130 and the second protective layer 140 are less likely to damage the barrier layer 120.

  The manufacturing method of the laminated body which concerns on one situation of embodiment mentioned above has the board | substrate formed using the resin material, and the barrier layer formed using the inorganic material so that the said board | substrate may be protected. A first step of arranging the laminate, and a second step of cutting the laminate using a punching die having a cutting blade, wherein the cutting blade is formed on the barrier layer. After entering, the substrate enters the substrate.

  According to the said structure, the laminated body which has the board | substrate formed using the resin material and the barrier layer formed using the inorganic material so that a board | substrate may be protected is arrange | positioned in a 1st process. In the second step, the laminate is cut by a punching die having a cutting blade. Since the cutting blade enters the substrate after entering the barrier layer, the barrier layer is not easily destroyed.

  In the above structure, the barrier layer is more susceptible to brittle fracture than the substrate.

  According to the above configuration, since the barrier layer is formed using an inorganic material, it is more susceptible to brittle fracture than a substrate formed using a resin material. However, since the cutting blade enters the substrate after entering the barrier layer in the second step, the barrier layer is not easily destroyed.

  The said structure WHEREIN: The said laminated body contains the 1st protective layer which covers the said barrier layer, and the 2nd protective layer which covers the said board | substrate, In the said 2nd process, the said cutting blade is a said 1st protective layer. After entering, it is preferable to enter the barrier layer and enter the substrate and then enter the second protective layer.

  According to the said structure, a laminated body contains the 1st protective layer which covers a barrier layer, and the 2nd protective layer which covers a board | substrate. Since the cutting blade enters the first protective layer, then enters the barrier layer, and enters the substrate and then enters the second protective layer, the first protective layer and the second protective layer enter the barrier layer. Relieve stress concentration. Therefore, the barrier layer is not easily destroyed.

  The said structure WHEREIN: It is preferable to push a double blade into the said laminated body as said cutting blade in a said 2nd process.

  According to the said structure, in a 2nd process, since both blades are pushed into a laminated body as a cutting blade, a barrier layer becomes difficult to be destroyed.

  In the above configuration, in the second step, it is preferable that a double-edged blade having a cutting edge angle of 30 ° or less is pushed into the laminate as the cutting blade.

  According to the said structure, in a 2nd process, since both the blades which have a blade edge angle of 30 degrees or less are pushed into a laminated body as a cutting blade, a barrier layer becomes difficult to be destroyed.

  In the above configuration, the substrate is preferably a flexible substrate.

  According to the said structure, the barrier layer laminated | stacked on the flexible substrate becomes difficult to be destroyed.

  In the above configuration, it is preferable that the barrier layer is formed using SiON, and the substrate is formed using polyimide.

  According to the said structure, since a board | substrate is formed using a polyimide, it becomes a suitable flexible substrate. Since the barrier layer is formed using SiON, the flexible substrate is appropriately protected.

  In the above configuration, the first protective layer and the second protective layer are preferably formed using PET.

  According to the said structure, since a 1st protective layer and a 2nd protective layer are formed using PET, the stress concentration added to a barrier layer in a 2nd process is relieve | moderated appropriately.

  The said structure WHEREIN: It is preferable that the said cutting blade is mirror-polished.

  According to the said structure, since the cutting blade is mirror-polished, a barrier layer becomes difficult to be destroyed.

  The principle according to the above-described embodiment is preferably applied to the cutting of a laminate including a substrate and a barrier layer.

100, 100A ... laminate 110 ... substrate 120 ... barrier layer 200 ... Thomson type 211- ···················································································· cutting blade 214

Claims (9)

A first step of disposing a laminate having a substrate formed using a resin material and a barrier layer formed using an inorganic material so as to protect the substrate;
A second step of cutting the laminate using a punching die having a cutting blade,
In the second step, the cutting blade enters the substrate after entering the barrier layer.   The cutting method according to claim 1, wherein the barrier layer is more susceptible to brittle fracture than the substrate. The laminate includes a first protective layer that covers the barrier layer, and a second protective layer that covers the substrate,
In the second step, the cutting blade enters the first protective layer, then enters the barrier layer, and enters the substrate, and then enters the second protective layer. The cutting method according to claim 1 or 2.   The cutting method according to any one of claims 1 to 3, wherein, in the second step, both blades are pushed into the laminated body as the cutting blade.   The cutting method according to any one of claims 1 to 3, wherein, in the second step, a double-edged blade having a cutting edge angle of 30 ° or less is pushed into the laminated body as the cutting blade.   The cutting method according to claim 1, wherein the substrate is a flexible substrate. The barrier layer is formed using SiON,
The cutting method according to claim 6, wherein the substrate is formed using polyimide.   The cutting method according to claim 3, wherein the first protective layer and the second protective layer are formed using PET.   The cutting method according to claim 1, wherein the cutting blade is mirror-polished.