Method for producing optical laminate with pressure-sensitive adhesive layer subjected to cutting

Abstract

The present invention provides a method for simply and cheaply manufacturing an optical laminate with an adhesive layer that has been cut, wherein the poor peeling of the surface protective film of the optical laminate is suppressed, and the tapered shape of the cut surface is suppressed. The method for manufacturing an optical laminate with an adhesive layer that has been cut of the present invention includes the following steps: overlapping a plurality of optical laminates with an adhesive layer to form a workpiece; cutting the outer peripheral surface of the workpiece using an end mill with a spiral blade; and further cutting the outer peripheral surface of the cut workpiece using an end mill with a blade angle of 0°. The optical laminate with an adhesive layer includes an optical film, an adhesive layer, a separator, and a surface protective film, wherein the adhesive layer is arranged on one side of the optical film, the separator is temporarily bonded to the adhesive layer in a releasable manner, and the protective film is temporarily bonded to the other side of the optical film in a releasable manner. In the manufacturing method of the present invention, the optical laminate with an adhesive layer is overlapped to form a workpiece in such a manner that the separator is located in the chip discharge direction of the end mill with a spiral blade.

Description

Technical Field

[0001] The present invention relates to a method for producing a cut-processed pressure-sensitive adhesive layer-attached optical laminate. Background Art

[0002] In order to realize image display and / or improve the image display performance, image display devices such as mobile phones and notebook personal computers use various optical laminates (such as polarizers). Representatively, an adhesive layer is set as the outermost layer in the optical laminate, and the optical laminate can be attached to the image display device. In terms of practicality, the adhesive layer is temporarily bonded to the separator in a removable manner, and the adhesive layer can be protected until the actual use. Furthermore, the optical laminate is temporarily bonded to the surface protection film in a removable manner on the opposite side of the adhesive layer. In recent years, it is expected that the shape of the optical laminate is processed into a desired shape. As such a processing method, for example, end face cutting using an end mill can be cited.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-22140 Summary of the invention

[0006] Problems to be solved by the invention

[0007] Here, when the optical laminate is bonded to other optical components, the surface protective film is required to be easy to peel (hereinafter, sometimes referred to as peelability). In addition, in the case of end face cutting using an end mill, the cutting surface sometimes becomes tapered when viewed from the horizontal direction. The present invention is completed to solve such a problem, and its main purpose is to provide a method for simply and cheaply manufacturing an optical laminate with an adhesive layer after cutting, wherein the surface protective film of the optical laminate is prevented from peeling poorly, and the cutting surface is prevented from becoming tapered.

[0008] Means used to solve problems

[0009] The method for manufacturing a cut optical laminate with an adhesive layer of the present invention comprises the following steps: overlapping a plurality of optical laminates with an adhesive layer to form a workpiece; cutting the outer peripheral surface of the workpiece using an end mill with a spiral blade; and further cutting the outer peripheral surface of the cut workpiece using an end mill with a blade angle of 0°. The optical laminate with an adhesive layer comprises an optical film, an adhesive layer, a separator, and a surface protective film, wherein the adhesive layer is arranged on one side of the optical film, the separator is temporarily bonded to the adhesive layer in a releasable manner, and the surface protective film is temporarily bonded to the other side of the optical film in a releasable manner. In the manufacturing method of the present invention, the optical laminate with an adhesive layer is overlapped in such a manner that the separator is located in the chip discharge direction of the end mill with a spiral blade to form the workpiece.

[0010] In one embodiment, the end mill with a spiral blade is a right-handed right spiral or a left-handed left spiral, and the optical laminate with an adhesive layer is overlapped so that the separator is located on the upper side to form a workpiece. In another embodiment, the end mill with a spiral blade is a right-handed left spiral or a left-handed right spiral, and the optical laminate with an adhesive layer is overlapped so that the separator is located on the lower side to form a workpiece.

[0011] In one embodiment, the amount of cutting by the end mill having the spiral blade is 0.1 mm to 0.5 mm, and the amount of cutting by the end mill having the blade angle of 0° is 0.01 mm to 0.2 mm.

[0012] In one embodiment, the manufacturing method includes the step of causing the surface protection film to warp by cutting with the end mill having the spiral blade. In one embodiment, the amount of warping of the surface protection film is 1 μm to 1000 μm.

[0013] In one embodiment, the manufacturing method includes the following step: performing non-linear cutting on the outer peripheral surface of the workpiece. In one embodiment, the non-linear cutting includes the following step: forming a concave portion including a curved portion when the optical laminate with the adhesive layer is viewed from above. In one embodiment, the radius of the curved portion is 5 mm or less.

[0014] In one embodiment, the optical film is a polarizer or a polarizing plate.

[0015] Effects of the Invention

[0016] According to the present invention, a method for manufacturing an optical laminate with an adhesive layer is provided, the method comprising the following steps: overlapping a plurality of optical laminates with an adhesive layer to form a workpiece, and cutting the outer peripheral surface of the workpiece using an end mill, wherein the outer peripheral surface is cut using an end mill having a spiral blade, and then the cut surface is further cut using an end mill having a blade angle of 0°, and the optical laminates with an adhesive layer are overlapped to form a workpiece in such a manner that a partition is located in a chip discharge direction of the end mill having a spiral blade, and the formed workpiece is cut, thereby realizing a method for simply and cheaply manufacturing an optical laminate with an adhesive layer that has been cut, wherein poor peeling of the surface protective film of the optical laminate with an adhesive layer that has been cut is suppressed, and the cutting surface is suppressed from becoming tapered. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic cross-sectional view for explaining an example of an optical laminate with a pressure-sensitive adhesive layer that can be used in the production method of the present invention.

[0018] Figure 2 This is a schematic diagram for explaining a typical example of the structure of an end mill having a spiral blade that can be used in the manufacturing method of the present invention.

[0019] Figure 3 This is a schematic plan view for explaining the difference in cutting direction between when the end mill with a spiral blade that can be used in the manufacturing method of the present invention has a right-hand blade and when it has a left-hand blade.

[0020] Figure 4 (a) is a schematic front view of an important part for explaining a method for forming a workpiece in one embodiment of the present invention; Figure 4 (b) is a schematic front view of an important part for explaining a method for forming a workpiece according to another embodiment.

[0021] Figure 5 It is a perspective schematic diagram for explaining the cutting process in the manufacturing method of the present invention.

[0022] Figure 6 This is a schematic diagram for explaining the structure of an end mill having a spiral blade used for cutting in the manufacturing method of the present invention.

[0023] Figure 7 This is a schematic diagram for explaining the structure of an end mill with a cutting edge angle of 0° used for cutting in the manufacturing method of the present invention.

[0024] Figure 8 This is a schematic plan view showing an example of the shape of a pressure-sensitive adhesive layer-attached optical laminated body obtained by the production method of the present invention after cutting.

[0025] Fig. 9 (a) to (c) are schematic plan views for explaining a series of steps of cutting processing in the production method of the present invention. DETAILED DESCRIPTION

[0026] Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited to these embodiments. In addition, the accompanying drawings are schematically shown for ease of observation, and further, the ratios and angles of the length, width, thickness, etc. in the accompanying drawings are different from the actual ones.

[0027] The manufacturing method of the optical laminate with adhesive layer of the present invention comprises: overlapping a plurality of optical laminates with adhesive layer to form a workpiece; cutting the outer peripheral surface of the workpiece using an end mill with a spiral blade; and further cutting the outer peripheral surface of the workpiece cut using an end mill with a blade angle of 0°. The optical laminate with adhesive layer comprises an optical film, an adhesive layer, a separator and a surface protective film, wherein the adhesive layer is arranged on one side of the optical film, the separator is temporarily bonded to the adhesive layer in a removable manner, and the protective film is temporarily bonded to the other side of the optical film in a removable manner. In an embodiment of the present invention, the optical laminate with adhesive layer is overlapped in such a manner that the separator is located in the chip discharge direction of the end mill with a spiral blade to form the workpiece. For convenience, the specific structure of the optical laminate with adhesive layer that can be used in the manufacturing method of the optical laminate with adhesive layer of the present invention is first described, and then the manufacturing method of the optical laminate with adhesive layer of the present invention is described.

[0028] A. Optical laminate with adhesive layer

[0029] Figure 1It is a cross-sectional schematic diagram illustrating an example of an optical laminate with an adhesive layer that can be used in the manufacturing method of the present invention. The optical laminate 100 with an adhesive layer shown in the figure includes an optical film 10, an adhesive layer 20, a separator 30 and a surface protective film 40, the adhesive layer 20 is arranged on one side of the optical film 10, the separator 30 is temporarily bonded to the adhesive layer 20 in a removable manner, and the surface protective film 40 is temporarily bonded to the other side of the optical film 10 in a removable manner. When the optical laminate with an adhesive layer is applied to an image display device, the separator 30 is typically arranged on the image display unit side. When the optical laminate with an adhesive layer is actually used, the separator 30 is peeled off and removed, and the adhesive layer 20 can be used to bond the optical laminate with an adhesive layer to an image display device (substantially an image display unit). The surface protective film 40 typically has a substrate 41 and an adhesive layer 42. In addition, in order to distinguish it from the adhesive layer 20, the adhesive layer 42 of the surface protective film is sometimes referred to as a "PF adhesive layer". The surface protection film 40 is also peeled off and removed when the optical laminate with adhesive layer is actually used. In the embodiment of the present invention, by adopting the manufacturing method described below, it is possible to realize an optical laminate with adhesive layer that has been cut and processed and in which poor peeling of the surface protection film is suppressed. That is, according to the embodiment of the present invention, it is possible to suppress the problem that is unique to the optical laminate with adhesive layer including the adhesive layer, the separator and the surface protection film, that is, it is possible to suppress poor peeling of the surface protection film.

[0030] As the optical film 10, any suitable optical film that can be used for applications requiring cutting (particularly non-linear processing) can be listed. The optical film can be a film consisting of a single layer or a laminate. As a specific example of an optical film consisting of a single layer, for example, a polarizer and a phase difference film can be listed. As a specific example of an optical film consisting of a laminate, a polarizer (representatively a laminate of a polarizer and a protective film), a conductive film for a touch panel, a surface treatment film, and a laminate formed by appropriately stacking an optical film consisting of these single layers and / or an optical film consisting of a laminate according to the purpose (for example, a circular polarizer for anti-reflection, a polarizer with a conductive layer for a touch panel).

[0031] As the adhesive layer 20, any appropriate structure can be adopted. Specific examples of the adhesive constituting the adhesive layer include: acrylic adhesive, rubber adhesive, silicone adhesive, polyester adhesive, urethane adhesive, epoxy adhesive and polyether adhesive. By adjusting the monomer type, quantity, combination and mixing ratio of the base resin forming the adhesive, as well as the mixing amount of the cross-linking agent, reaction temperature, reaction time, etc., an adhesive having the desired properties corresponding to the purpose can be prepared. The base resin of the adhesive can be used alone or in combination of two or more. From the viewpoints of transparency, processability and durability, acrylic adhesive is preferred. The details of the adhesive constituting the adhesive layer are described in, for example, Japanese Patent Gazette No. 2014-115468, and this specification cites the contents of the gazette as a reference. The thickness of the adhesive layer 20 can be, for example, 10μm to 100μm. The storage modulus G' of the adhesive layer 20 at 25°C can be, for example, 1.0×10 4 (Pa)~1.0×10 6 (Pa) The storage modulus can be obtained, for example, by dynamic viscoelasticity measurement.

[0032] The separator 30 may be any appropriate separator. As specific examples, plastic films, nonwoven fabrics or papers coated with a release agent may be cited. As specific examples of release materials, silicone release agents, fluorine release agents, and long-chain alkyl acrylate release agents may be cited. As specific examples of plastic films, polyethylene terephthalate (PET) films, polyethylene films, and polypropylene films may be cited. The thickness of the separator may be, for example, 10 μm to 100 μm.

[0033] As described above, the surface protection film 40 typically has a substrate 41 and an adhesive layer 42. As the forming material of the substrate 41, for example, ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, and copolymer resins thereof can be cited. Ester resins (especially polyethylene terephthalate resins) are preferred. As long as such a material is used, it has the advantages of having a sufficiently high elastic modulus and being less likely to deform even when tension is applied during transportation and / or lamination.

[0034] The elastic modulus of the substrate 41 may be, for example, 2.2 kN / mm 2 ~4.8kN / mm 2 When the elastic modulus of the substrate is within such a range, there is an advantage that deformation is not easily caused even when tension is applied during transportation and / or lamination. The elastic modulus is measured in accordance with JIS K 6781.

[0035] The thickness of the substrate 41 is, for example, 30 μm to 70 μm.

[0036] The adhesive layer (PF adhesive layer) 42 can be of any appropriate composition. As specific examples, there can be cited: acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives and polyether adhesives. By adjusting the monomer type, quantity, combination and proportion of the base resin forming the adhesive, the amount of the cross-linking agent, the reaction temperature, the reaction time, etc., an adhesive having the desired properties corresponding to the purpose can be prepared. The base resin of the adhesive can be used alone or in combination of two or more. The adhesive constituting the PF adhesive layer has the following characteristics: the base resin contains a polymer having a functional group containing active hydrogen. As long as it is such a base resin, a PF adhesive layer with a desired storage modulus can be obtained. The details of the adhesive constituting the PF adhesive layer are recorded, for example, in Japanese Patent Publication No. 2018-123281, and this specification cites the contents of the publication as a reference. The thickness of the PF adhesive layer 42 can be, for example, 10μm to 100μm. The storage modulus G' of the PF adhesive layer 42 at 25°C may be, for example, 0.5×10 6 (Pa)~3.0×10 6 (Pa). As long as the storage modulus is within such a range, an adhesive layer (resulting in a surface protection film) having an excellent balance between adhesion and peelability can be obtained. Furthermore, by the manufacturing method described later, the surface protection film can be warped, and as a result, the warped portion can be used as a gripping edge to easily concentrate stress on the peeling point, thereby maintaining an acceptable adhesion and achieving a more excellent peelability.

[0037] The thickness of the surface protection film 40 may be, for example, 40 μm to 120 μm. The thickness of the surface protection film refers to the total thickness of the substrate and the PF adhesive layer.

[0038] In one embodiment, the peeling force between the separator 30 and the adhesive layer 20 (hereinafter also referred to as the peeling force of the separator) is smaller than the peeling force between the optical film 10 and the surface protective film 40 (substantially the PF adhesive layer 42) (hereinafter also referred to as the peeling force of the surface protective film). In most cases, the peeling force of the surface protective film is greater than the peeling force of the separator, which is prone to poor peeling of the surface protective film, but according to the manufacturing method described later, an optical laminate with an adhesive layer that has been cut and in which poor peeling of the surface protective film is suppressed can be obtained. More specifically, the peeling force of the separator is preferably 0.001N / 10mm~1.0N / 10mm, and the peeling force of the surface protective film is preferably 0.01N / 10mm~5.0N / 10mm. The peeling force of the separator is preferably 0.001~0.1N / 10mm, and more preferably 0.005~0.03N / 10mm. The peeling force of the surface protective film is preferably 0.01 to 0.5 N / 10 mm, more preferably 0.035 to 0.1 N / 10 mm. The difference between the peeling force of the separator and the peeling force of the surface protective film (peeling force of the surface protective film - peeling force of the separator) is preferably 0.01 N / 10 mm to 1.0 N / 10 mm. According to the manufacturing method described below, even if there is such a difference in peeling force, an optical laminate with an adhesive layer that has been cut and in which poor peeling of the surface protective film is suppressed can be obtained.

[0039] In one embodiment, the thickness of the surface protection film 40 is greater than the thickness of the separator 30. By the manufacturing method described later, even if the thickness of the surface protection film is very thick and a large peeling force is required as described above, excellent peeling properties can be achieved. The difference between the thickness of the surface protection film and the thickness of the separator (the thickness of the surface protection film-the thickness of the separator) is preferably 5μm to 60μm. According to the manufacturing method described later, even if there is such a difference in thickness, an optical laminate with an adhesive layer that has been cut and in which poor peeling of the surface protection film is suppressed can be obtained.

[0040] B. Method for producing an optical laminate with an adhesive layer

[0041] A typical example of a method for producing an optical laminate with a pressure-sensitive adhesive layer is described below. First, the relationship between the structure of an end mill with a spiral blade and the stacking state of the workpiece, which is a characteristic portion of the present invention, is described, and then the outline of the production method is described.

[0042] B-1. Relationship between the structure of the end mill and the stacking state of the workpiece

[0043] In the embodiment of the present invention, as described above, the optical laminate with the pressure-sensitive adhesive layer is stacked to form a workpiece so that the separator is located in the chip discharge direction of the end mill having a spiral blade, and the outer peripheral surface of the workpiece is cut. Figure 2 and Figure 3 The following will be described in detail. Figure 2 This is a schematic diagram for explaining a typical example of the structure of an end mill having a spiral blade that can be used in the manufacturing method of the present invention. Figure 3 This is a top view schematic diagram illustrating the difference in cutting direction when the end mill with a spiral blade is right-handed and left-handed. Figure 2 As shown in FIG. 1 , the structure of the end mill with spiral blades is roughly divided into right-edge right spiral, right-edge left spiral, left-edge right spiral, and left-edge left spiral. Figure 2 As shown in the figure, the right blade refers to the structure that can be cut when viewed from the upper side (handle side) and rotated clockwise; the left blade refers to the structure that can be cut when viewed from the upper side (handle side) and rotated counterclockwise. Figure 2 As further shown, a right spiral refers to a structure in which the blade tip extends obliquely upward to the right when viewed from the side; a left spiral refers to a structure in which the blade tip extends obliquely upward to the left when viewed from the side. The chip discharge direction of a right-blade right spiral and a left-blade left spiral is upward; the chip discharge direction of a right-blade left spiral and a left-blade right spiral is downward. Figure 3 As shown, the cutting direction of the right edge is typically counterclockwise, and the cutting direction of the left edge is typically clockwise.

[0044] In the embodiment of the present invention, as described above, the optical laminate with the adhesive layer is stacked so that the separator is located in the chip discharge direction of the end mill with a spiral blade to form a workpiece, and the outer peripheral surface of the workpiece is cut. For example, when the end mill with a spiral blade is a right-handed right spiral or a left-handed left spiral, as Figure 4 As shown in (a), the optical laminate with the adhesive layer is stacked so that the separator is located on the upper side to form a workpiece W. On the other hand, when the end mill is a right-edge left-hand helical or a left-edge right-hand helical, as shown in Figure 4As shown in (b), the optical laminate with an adhesive layer is overlapped in such a way that the separator is located on the lower side to form a workpiece W. The inventors have found that: depending on the relationship between the chip discharge direction of the end mill with a spiral blade and the configuration of the surface protective film of the optical laminate with an adhesive layer in the workpiece, there are situations where the surface protective film is warped and situations where it does not warp; further, by causing the surface protective film to warp, the problem of poor peeling of the surface protective film can be solved. As long as it is as described above, by cutting (or cutting down) the optical laminate with an adhesive layer from the surface protective film side toward the separator side, the surface protective film that is given a strong cutting force in the oblique direction can be caused to warp. Thus, a cut optical laminate with an adhesive layer in which poor peeling of the surface protective film is suppressed can be obtained. The warping amount of the surface protective film is preferably 1 μm or more, more preferably 20 μm or more, and further preferably 50 μm or more. On the other hand, the warping amount is preferably 1000 μm or less, more preferably 500 μm or less. As long as the amount of warping is within such a range, no other adverse conditions will occur, the appearance quality will be maintained within an allowable range, and good peelability of the surface protection film can be achieved. Warping will reduce the appearance quality, so in the art, warping is avoided as much as possible, but according to an embodiment of the present invention, by actively causing the surface protection film to warp, a technical concept that completely goes against the technical common sense in the art, an optical laminate with an adhesive layer that has been cut and in which poor peeling is suppressed can be obtained. In addition, if the relationship between the structure of the end mill with a spiral blade and the stacking state of the workpiece is reversed (that is, if the end mill with a spiral blade is a right-handed right-helical or a left-handed left-helical such as Figure 4 (b) and in the case where the end mill with a helical blade is a right-handed left-hand helical or a left-handed right-hand helical Figure 4 (a)), the separator will be lifted, but the surface protection film will not be lifted. As a result, the problem of poor peeling of the surface protection film may not be eliminated.

[0045] B-2. Workpiece Formation

[0046] Next, the outline of the cutting process will be described. Figure 5 This is a three-dimensional schematic diagram for explaining the cutting process in the manufacturing method of the present invention, in which a workpiece W is shown. Figure 5 As shown in FIG. 1 , a workpiece W is formed by stacking a plurality of optical laminates with adhesive layers. As described in item B-1, according to the structure of the end mill with a spiral blade, as shown in FIG. Figure 4 (a) or Figure 4(b) The stacking state of the workpiece W is set as shown. The optical laminate with an adhesive layer is typically cut into any appropriate shape when forming the workpiece. Specifically, the optical laminate with an adhesive layer can be cut into a rectangular shape, can be cut into a shape that is approximately rectangular, and can also be cut into an appropriate shape corresponding to the purpose (for example, a circle). The workpiece W has outer peripheral surfaces (cutting surfaces) 1a, 1b that are opposite to each other and outer peripheral surfaces (cutting surfaces) 1c, 1d that are orthogonal to them. The workpiece W is preferably clamped from top to bottom by a clamping mechanism (not shown). The total thickness of the workpiece is preferably 8mm to 20mm, more preferably 9mm to 15mm, and further preferably about 10mm. As long as it is such a thickness, it is possible to prevent damage caused by pressure caused by the clamping mechanism or by impact during cutting. For an optical laminate with an adhesive layer, the workpiece is overlapped to such a total thickness. The number of sheets of the optical laminate with an adhesive layer constituting the workpiece can be, for example, 10 to 50 sheets. The clamping mechanism (e.g., a fixture) may be made of a soft material or a hard material. When made of a soft material, its hardness (JISA) is preferably 60° to 80°. If the hardness is too high, there may be a case where an indentation caused by the clamping mechanism remains. If the hardness is too low, the deformation of the fixture may cause positional deviation and the cutting accuracy may become insufficient.

[0047] B-3. ​​Cutting

[0048] B-3-1. Cutting with an end mill having a spiral blade

[0049] Next, the outer peripheral surface of the workpiece W is cut by the end mill 60 having a spiral blade. Cutting is typically performed by bringing the cutting edge of the end mill into contact with the outer peripheral surface of the workpiece W. Cutting may be performed over the entire outer peripheral surface of the workpiece or only at a predetermined position.

[0050] like Figure 6As shown, the end mill 60 with a spiral blade has a rotation axis 61 and a cutting edge 62, the rotation axis 61 extends along the stacking direction (vertical direction) of the workpiece W, and the cutting edge 62 is configured as the outermost diameter of the body rotating around the rotation axis 61. In the example shown in the figure, the cutting edge 62 is configured as the outermost diameter of the spiral along the rotation axis 61, and shows a right-hand spiral. The cutting edge 62 includes a cutting edge 62a, a front cutting edge 62b and a retreat surface 62c. The number of blades of the cutting edge 62 can be appropriately set according to the purpose. The cutting edge in the example shown in the figure is composed of three pieces, but the number of blades can be a continuous piece, two pieces, four pieces, or more than five pieces. The blade angle of the end mill (the helix angle θ of the cutting edge in the example shown in the figure) is preferably 20° to 60°, and more preferably 30° to 45°. As long as it is such a blade angle, the surface protective film can be well raised by cutting. The retreat surface of the cutting edge is preferably roughened. The roughening treatment may be any appropriate treatment. A representative example is sandblasting. By roughening the retreat surface, it is possible to suppress adhesion of the adhesive to the cutting edge, resulting in suppression of sticking. The outer diameter of the end mill is preferably 3 mm to 20 mm. In addition, in this specification, "sticking" refers to the phenomenon that the optical stacks with adhesive layers in the workpiece are bonded to each other with adhesive at the end faces, and the chips of the adhesive attached to the end faces help the optical stacks with adhesive layers to stick to each other. In addition, the "outer diameter of the end mill" refers to the value obtained by multiplying the distance from the rotating shaft 61 to the blade tip 62a by two times. The end mill can be a single-sided fixed end mill held at one end (upper end), or a double-sided fixed end mill held at both ends (upper end and lower end).

[0051] In the embodiment of the present invention, cutting by a spiral-edged end mill can be equivalent to so-called rough cutting. First, cutting is performed by a spiral-edged end mill, and then the cutting surface is further cut (finished) using an end mill with a blade angle of 0° as described later, thereby preventing the surface protective film from peeling off poorly and preventing the cutting surface from becoming tapered. The cutting amount by the spiral-edged end mill is preferably about 0.1 mm to 0.5 mm.

[0052] B-3-2. Cutting with an end mill with a cutting edge angle of 0°

[0053] In the embodiment of the present invention, after cutting with an end mill having a spiral blade, Figure 7The end mill with a blade angle of 0° shown further cuts the cutting surface. This can be equivalent to so-called finishing. As long as it is such a structure, it is possible to suppress the poor peeling of the surface protection film and to suppress the cutting surface from becoming tapered. In more detail, by using an end mill with a spiral blade to cut in a prescribed manner, the surface protection film is caused to warp as described in the above-mentioned item B-1, and the poor peeling of the surface protection film can be suppressed. On the other hand, there is a situation where the cutting surface becomes tapered based on the cutting of the end mill with a spiral blade, but by further cutting the cutting surface with an end mill with a blade angle of 0°, such a tapered cutting surface can be eliminated. Furthermore, on the cutting surface side of the optical laminate with an adhesive layer based on the end mill with a spiral blade, the warping of the surface protection film may cause an unacceptable reduction in the appearance quality, but by cutting based on the end mill with a blade angle of 0°, such a portion with reduced appearance quality can be removed. In addition, by cutting based on the end mill with a blade angle of 0°, the amount of warping of the surface protection film generated by cutting based on the end mill with a spiral blade can be appropriately adjusted. The cutting amount based on the end mill with a blade angle of 0° is preferably about 0.01mm to 0.2mm. The cutting based on the end mill with a blade angle of 0° is fine cutting, and its cutting amount is typically significantly smaller than the cutting amount based on the end mill with a spiral blade (rough cutting amount). As a result, the amount of warping of the surface protection film can be appropriately adjusted, resulting in no other adverse conditions, and the good peelability of the surface protection film can be achieved while maintaining the appearance quality within an allowable range. Furthermore, the end mill with a spiral blade with high versatility can contribute to most of the cutting, so the manufacturing method of the present invention is also advantageous from a cost perspective. In addition, in this specification, "the blade angle is 0°" means that the blade tip 62a extends in a direction substantially parallel to the rotation axis, in other words, it means that the blade is not twisted about the rotation axis. In addition, "0°" means substantially 0°, and also includes slight angle twisting caused by processing errors, etc. In addition, "tapered cutting surface" means that when the cutting surface is observed from the horizontal direction, the cutting surface is offset and extended from the vertical direction to the oblique direction.

[0054] B-3-3. Others

[0055] In one embodiment, the manufacturing method of the present invention includes the following steps: performing non-linear cutting on the outer peripheral surface of the workpiece. Non-linear cutting, for example, Figure 8 The method includes the following steps: forming a concave portion 4c including a curved portion when the optical laminate with the adhesive layer is viewed from above. Figure 8When an optical laminate with an adhesive layer having the top view shape shown in the figure is formed, the periphery of the workpiece is linearly cut, and chamfered portions 4a and 4b are formed at two corners of the periphery of the workpiece, and a recess (including a recessed portion of a curved portion) 4c is formed in the central portion of the periphery where the chamfered portions 4a and 4b are formed. By forming such a recess, the surface protective film can be caused to warp near the recess. As a result, the peelability of the surface protective film when it is peeled off from the recess can be improved. Refer to Fig. 9 (a)~ Fig. 9 (c) An example of such cutting processing is described. Fig. 9 (a) shows the formation of Figure 8 The chamfered portion 4a is chamfered, and then Fig. 9 (b) The portion forming the chamfered portion 4b is chamfered. Fig. 9 As shown in (c), a concave portion (including a concave portion of a curved portion) 4c is cut to form. The radius of the curved portion is preferably 5 mm or less, more preferably 4 mm or less, and further preferably 3 mm or less. In addition, the formation order (cutting order) of the chamfered portions 4a and 4b and the concave portion 4c is not limited, and they can be formed in any appropriate order.

[0056] The conditions of the cutting process can be appropriately set according to the desired shape. The rotation speed of the end mill with a spiral blade and the end mill with a blade angle of 0° is preferably 1000rpm to 60000rpm, and more preferably 10000rpm to 40000rpm. The feed rate of the end mill with a spiral blade and the end mill with a blade angle of 0° is preferably 500mm / min to 10000mm / min, and more preferably 500mm / min to 2500mm / min. The number of cuttings at the cutting location can be one cutting, two cuttings, three cuttings or more.

[0057] The optical laminate with a pressure-sensitive adhesive layer obtained by the production method of the present invention can suppress the failure of the surface protective film to be peeled off and suppress the cut surface from becoming tapered.

[0058] Example

[0059] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. Evaluation items of the examples are as follows.

[0060] (1) The rate of warping of the surface protection film

[0061] An arbitrary number (preferably 100 or more) of optical laminates with adhesive layers after cutting were prepared, and the warping of the surface protective film was observed using a magnifying glass or a microscope. The entire periphery of each optical laminate with adhesive layer was observed, and if warping of 1 μm or more was observed, the optical laminate with adhesive layer was counted as a sample with warping, and the warping generation rate was calculated by "(samples with warping / number of observations)×100".

[0062] (2) Peeling success rate

[0063] 50 optical laminates with adhesive layers obtained in Examples and Comparative Examples were randomly selected and the surface protective films were peeled off (initial peeling force was 2.9 N). The number of times peeling was performed without problems among 50 peelings was expressed as a percentage and was defined as the peeling success rate.

[0064] (3) Warping amount

[0065] The amount of warping of the surface protective film in the cut pressure-sensitive adhesive layer-attached optical laminates obtained in Examples and Comparative Examples was measured using a magnifying glass or a microscope. The maximum value of the warping amount of one workpiece was defined as the warping amount.

[0066] (4) Cone

[0067] The cut surfaces of the pressure-sensitive adhesive layer-attached polarizing plates obtained in Examples and Comparative Examples were observed from the horizontal direction using a scanning electron microscope (SEM) (magnification: 500 times). The cut surfaces observed from the horizontal direction were evaluated according to the following criteria.

[0068] ○: The cutting surface extends substantially in the vertical direction

[0069] ×: The cutting surface deviates from the vertical direction to the oblique direction

[0070] <Example 1>

[0071] A polarizer with an adhesive layer having the structure of surface protection film (60μm) / cycloolefin protective film (47μm) / polarizer (5μm) / cycloolefin protective film (24μm) / adhesive layer (20μm) / separator in order from the visual confirmation side was prepared by conventional methods. In addition, a surface protective film having the structure of PET substrate (50μm) / PF adhesive layer (10μm) was prepared as a surface protective film and verified. At this time, the storage modulus of the adhesive layer (adhesive) was adjusted to 0.5MPa to 3.0MPa. The polarizer with an adhesive layer obtained in the above manner was punched into a size of 5.7 inches (length of 140mm and width of about 65mm), and then a plurality of punched polarizers were overlapped to form a workpiece (total thickness of about 10mm). While the obtained workpiece is clamped by a clamping device (clamp), chamfered portions are formed at two corners of the outer periphery of the workpiece by an end mill, and a concave portion (including a concave portion of a curved portion) is formed at the center of the outer periphery where the chamfered portion is formed, so that the following is obtained: Figure 8 The polarizer with an adhesive layer after cutting is shown. The cutting was performed twice, namely, rough cutting and finish cutting. Rough cutting (first cutting) was performed using an end mill with a right-handed right-hand spiral and a helix angle of 30° (the discharge direction of the cutting chips was upward), and the cutting amount was 0.2 mm. Finishing cutting (second cutting) was performed using an end mill with a blade angle of 0° and a cutting amount of 0.1 mm. The rate of warping of the surface protective film caused by cutting was 100%. The obtained polarizer with an adhesive layer after cutting was evaluated by the above (2) to (4). The results are shown in Table 1.

[0072] <Example 2>

[0073] Cutting was performed in the same manner as in Example 1 except that a right-handed right-hand helix end mill with a helix angle of 45° was used for rough cutting (first cutting). The cut pressure-sensitive adhesive layer-attached polarizing plate obtained was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0074] <Comparative Example 1>

[0075] The cutting process was performed in the same manner as in Example 1, except that the finishing cutting (second cutting) by the end mill with a cutting angle of 0° was not performed. The obtained cut pressure-sensitive adhesive layer-attached polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0076] <Comparative Example 2>

[0077] The cutting process was performed in the same manner as in Example 2 except that the finishing cutting (second cutting) by the end mill with a cutting angle of 0° was not performed. The obtained cut pressure-sensitive adhesive layer-attached polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0078] <Comparative Example 3>

[0079] The cutting process was performed in the same manner as in Example 1, except that an end mill with a blade angle of 0° was used for rough cutting (first cutting) and an end mill with a right-hand blade and a right-hand helix and a helix angle of 30° was used for finishing cutting (second cutting). The obtained cut polarizing plate with an adhesive layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0080] <Comparative Example 4>

[0081] The cutting process was performed in the same manner as in Example 2, except that an end mill with a blade angle of 0° was used for rough cutting (first cutting) and an end mill with a right-hand blade and a right-hand helix and a helix angle of 45° was used for finishing cutting (second cutting). The obtained cut polarizing plate with an adhesive layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0082] <Comparative Example 5>

[0083] Cutting was performed in the same manner as in Example 1, except that an end mill with a cutting angle of 0° was used for both rough cutting (first cutting) and finishing cutting (second cutting). The obtained cut pressure-sensitive adhesive layer-attached polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0084] <Comparative Example 6>

[0085] The cutting process was performed in the same manner as in Example 1, except that a right-handed right-hand helix end mill with a helix angle of 30° was used for both the rough cutting (first cutting) and the finishing cutting (second cutting). The obtained cut polarizing plate with an adhesive layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0086] <Comparative Example 7>

[0087] Cutting was performed in the same manner as in Example 1, except that a right-handed right-hand helix end mill with a helix angle of 45° was used for both rough cutting (first cutting) and finishing cutting (second cutting). The obtained cut polarizing plate with an adhesive layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0088] <Comparative Example 8>

[0089] Cutting was performed in the same manner as in Example 1 except that the workpiece was stacked so that the separator of the pressure-sensitive adhesive layer-attached polarizing plate was located at the bottom. The cut pressure-sensitive adhesive layer-attached polarizing plate obtained was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0090] <Comparative Example 9>

[0091] The cutting process was performed in the same manner as in Example 2 except that the workpiece was formed by stacking the separator of the pressure-sensitive adhesive layer-attached polarizing plate so as to be located at the bottom. The obtained cut pressure-sensitive adhesive layer-attached polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0092] Table 1

[0093]

[0094] <Evaluation>

[0095] It can be seen from Table 1 that according to an embodiment of the present invention, a method for manufacturing an optical laminate with an adhesive layer is provided, and the manufacturing method includes: overlapping a plurality of optical laminates with adhesive layers to form a workpiece, and cutting the outer peripheral surface of the workpiece using an end mill, wherein the outer peripheral surface is cut using an end mill with a spiral blade, and then the cutting surface is further cut using an end mill with a blade angle of 0°, and the optical laminates with adhesive layers are overlapped to form a workpiece in such a manner that the partition is located in the chip discharge direction of the end mill with a spiral blade, and the formed workpiece is cut, thereby making it possible to simply and inexpensively realize an optical laminate with an adhesive layer that is processed by cutting and in which poor peeling of the surface protective film is suppressed and the cutting surface is suppressed from becoming tapered.

[0096] Industrial Applicability

[0097] The manufacturing method of the present invention can be applied to the manufacture of an optical laminate with an adhesive layer that requires cutting processing (especially non-linear processing). The optical laminate with an adhesive layer obtained by the manufacturing method of the present invention can be applied to special-shaped image display parts represented by automobile instrument panels and smart watches.

[0098] Explanation of symbols

[0099] W Workpiece

[0100] 10 Optical film

[0101] 20 Adhesive layer

[0102] 30 Dividers

[0103] 40 Surface protection film

[0104] 60 End Mill

[0105] 100 Optical laminate with adhesive layer

Claims

1. A method for producing a cut optical laminate with an adhesive layer, comprising the following steps: Overlaying a plurality of optical laminates with adhesive layers to form a workpiece; cutting the outer peripheral surface of the workpiece using an end mill having a spiral blade; and The outer peripheral surface of the workpiece that has been cut is further cut using an end mill with a cutting angle of 0°. in, The optical laminate with adhesive layer comprises an optical film, an adhesive layer, a separator and a surface protection film, wherein the adhesive layer is arranged on one side of the optical film, the separator is temporarily bonded to the adhesive layer in a releasable manner, and the surface protection film is temporarily bonded to the other side of the optical film in a releasable manner. The end mill with spiral blades is a right-hand spiral or a left-hand spiral. The chip discharge direction of the end mill with spiral blades is upward. The optical laminate with pressure-sensitive adhesive layers is stacked so that the separator is located on the upper side to form a workpiece.

2. The manufacturing method according to claim 1, wherein: The cutting amount by the end mill with the spiral blade is 0.1 mm to 0.5 mm, and the cutting amount by the end mill with the blade angle of 0° is 0.01 mm to 0.2 mm.

3. The manufacturing method according to claim 1 or 2, wherein: Cutting by the end mill having the spiral blade causes the surface protection film to rise.

4. The manufacturing method according to claim 3, wherein: The warping amount of the surface protection film is 1 μm to 1000 μm. 5 . The manufacturing method according to claim 1 , comprising the step of performing non-linear cutting on the outer peripheral surface of the workpiece.

6. The manufacturing method according to claim 5, wherein: The non-linear cutting includes a step of forming a concave portion including a curved portion when the pressure-sensitive adhesive layer-attached optical laminate is viewed in plan.

7. The manufacturing method according to claim 6, wherein: The radius of the curved portion is 5 mm or less.

8. The manufacturing method according to claim 1 or 2, wherein: The optical film is a polarizer or a polarizing plate.

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