阅读说明：本技术 经切削加工的带粘合剂层的光学层叠体的制造方法 (Method for manufacturing optical laminate with adhesive layer by cutting ) 是由 高濑裕太 麓弘明 横内正 池内能满 伊崎章典 于 2019-11-15 设计创作，主要内容包括：本发明提供能够简便廉价地制造经切削加工的带粘合剂层的光学层叠体的方法,该光学层叠体的表面保护膜剥离不良得以抑制,并且切削面成为锥状得以抑制。本发明的经切削加工的带粘合剂层的光学层叠体的制造方法包括下述工序：将多片带粘合剂层的光学层叠体重叠而形成工件；使用具有螺旋刃的立铣刀对工件的外周面进行切削；以及使用刃角为0°的立铣刀对经切削的工件的外周面进一步进行切削。带粘合剂层的光学层叠体包含光学膜、粘合剂层、分隔件及表面保护膜,该粘合剂层配置于光学膜的一侧,该分隔件以可剥离方式与粘合剂层暂时粘合,保护膜以可剥离方式与光学膜的另一侧暂时粘合。本发明的制造方法中,以使分隔件位于具有螺旋刃的立铣刀的切屑排出方向的方式将带粘合剂层的光学层叠体重叠而形成工件。(The invention provides a method for simply and cheaply manufacturing an optical laminated body with a pressure-sensitive adhesive layer after cutting processing, wherein the surface protection film peeling failure of the optical laminated body is inhibited, and the cutting surface is inhibited from being tapered. The method for producing a cut optical laminate with an adhesive layer according to the present invention comprises the steps of: forming a work by overlapping a plurality of optical layered bodies with adhesive layers; cutting an outer peripheral surface of a workpiece using an end mill having a helical blade; and further cutting the outer peripheral surface of the cut workpiece using an end mill having an edge angle of 0 °. The optical laminate with an adhesive layer includes an optical film, an adhesive layer disposed on one side of the optical film, a separator temporarily bonded to the adhesive layer in a peelable manner, and a surface protective film temporarily bonded to the other side of the optical film in a peelable manner. In the manufacturing method of the present invention, the optical laminate with the adhesive layer is stacked so that the spacer is positioned in the chip discharge direction of the end mill having the helical blade, thereby forming the workpiece.)

1. A method for producing a cut optical laminate with an adhesive layer, comprising the steps of:

forming a work by overlapping a plurality of optical layered bodies with adhesive layers;

cutting the outer peripheral surface of the workpiece with an end mill having a helical blade; and

further cutting the outer peripheral surface of the cut workpiece with an end mill having an edge angle of 0 DEG,

wherein the optical laminate with the adhesive layer comprises an optical film, an adhesive layer, a separator and a surface protection film, the adhesive layer is arranged on one side of the optical film, the separator is temporarily bonded with the adhesive layer in a stripping manner, the surface protection film is temporarily bonded with the other side of the optical film in a stripping manner,

the work is formed by stacking the optical laminate with an adhesive layer so that the separator is positioned in the direction in which chips of the end mill having the helical blade are discharged.

2. The manufacturing method according to claim 1, wherein the end mill having the helical edge is a right-hand helix or a left-hand helix,

the optical laminate with the adhesive layer is stacked so that the separator is positioned on the upper side to form a work.

3. The manufacturing method according to claim 1, wherein the end mill having the helical edge is a right-hand left-handed helix or a left-hand right-handed helix,

the optical laminate with the adhesive layer is stacked such that the separator is positioned on the lower side to form a work.

4. The manufacturing method according to any one of claims 1 to 3, wherein a cutting amount by the end mill having the helical edge is 0.1mm to 0.5mm, and a cutting amount by the end mill having the edge angle of 0 ° is 0.01mm to 0.2 mm.

5. The manufacturing method according to any one of claims 1 to 4, wherein the surface protective film is turned up by cutting with the end mill having the helical edge.

6. The manufacturing method according to claim 5, wherein the amount of lift of the surface protective film is 1 μm to 1000 μm.

7. The manufacturing method according to any one of claims 1 to 6, comprising the steps of: and performing non-linear cutting on the outer peripheral surface of the workpiece.

8. The manufacturing method according to claim 7, wherein the non-linear cutting includes the steps of: and forming a concave portion including a curved portion in a plan view of the optical laminate with an adhesive layer.

9. The manufacturing method according to claim 8, wherein a radius of the curved portion is 5mm or less.

10. The manufacturing method according to any one of claims 1 to 9, wherein the optical film is a polarizer or a polarizing plate.

Technical Field

The present invention relates to a method for manufacturing a cut optical laminate with an adhesive layer.

Background

Image display devices such as mobile phones and notebook personal computers use various optical layered bodies (e.g., polarizing plates) in order to realize image display and/or improve the image display performance. Typically, the optical laminate may be bonded to an image display device by providing a pressure-sensitive adhesive layer as an outermost layer on the optical laminate. Practically speaking, temporary adhesion to the separator in a releasable manner on this adhesive layer can protect the adhesive layer until the time of actual use. Further, the optical laminate is temporarily bonded to a surface protective film typically in a releasable manner on the side opposite to the pressure-sensitive adhesive layer. In recent years, it has been desired to process the shape of an optical laminate into a desired shape. Examples of such a machining method include end face cutting using an end mill.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2018-22140

Disclosure of Invention

Problems to be solved by the invention

Here, when the optical laminate is bonded to another optical member, easy peelability of the surface protective film (hereinafter, sometimes simply referred to as peelability) is required. In the end face cutting process using an end mill, the cutting surface may be tapered when viewed in the lateral direction. The present invention has been made to solve the above problems, and has as its main object: provided is a method for simply and inexpensively producing an optical laminate with a pressure-sensitive adhesive layer, which is subjected to a cutting process, and in which a surface protective film peeling failure is suppressed and a taper of a cut surface is suppressed.

Means for solving the problems

The method for producing a cut optical laminate with an adhesive layer according to the present invention comprises the steps of: forming a work by overlapping a plurality of optical layered bodies with adhesive layers; cutting the outer peripheral surface of the workpiece with an end mill having a helical blade; and further cutting the outer peripheral surface of the cut workpiece by using an end mill having an edge angle of 0 °. The optical laminate with the 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 with the adhesive layer in a stripping manner, and the surface protection film is temporarily bonded with the other side of the optical film in a stripping manner. In the manufacturing method of the present invention, the work is formed by stacking the optical laminate with an adhesive layer so that the spacer is positioned in the chip discharge direction of the end mill having the helical blade.

In one embodiment, the end mill having the helical blade is a right-handed helix or a left-handed helix, and the optical layered body with the adhesive layer is stacked so that the separator is positioned on the upper side to form the work. In another embodiment, the end mill having the helical blade is a right-handed left-handed helix or a left-handed right-handed helix, and the optical layered body with the adhesive layer is stacked such that the separator is positioned on the lower side to form the work.

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

In one embodiment, the manufacturing method includes the steps of: the surface protection film is tilted by cutting with the end mill having the helical blade. In one embodiment, the amount of lift-off of the surface protective film is 1 μm to 1000 μm.

In one embodiment, the manufacturing method includes the steps of: and cutting the outer peripheral surface of the workpiece in a non-linear manner. In one embodiment, the non-linear cutting includes the steps of: and a concave portion including a curved portion when the optical laminate with the pressure-sensitive adhesive layer is viewed in a plan view. In one embodiment, the radius of the curved portion is 5mm or less.

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

Effects of the invention

According to the present invention, there is provided a method for producing an optical laminate with an adhesive layer, comprising the steps of: a method for simply and inexpensively producing a cut optical laminate with an adhesive layer, in which a plurality of optical laminates with an adhesive layer are stacked to form a workpiece, and the outer peripheral surface of the workpiece is cut with an end mill, wherein the outer peripheral surface is cut with an end mill having a helical blade, the cut surface is further cut with an end mill having a cutting edge angle of 0 DEG, and the cut workpiece is stacked to form a workpiece so that a separator is positioned in the chip discharge direction of the end mill having a helical blade, thereby enabling the production of a cut optical laminate with an adhesive layer in which the peeling failure of the surface protective film of the cut optical laminate is suppressed and the taper of the cut surface is suppressed.

Drawings

Fig. 1 is a schematic cross-sectional view illustrating an example of an optical laminate with an adhesive layer that can be used in the manufacturing method of the present invention.

Fig. 2 is a schematic view illustrating a typical example of the structure of an end mill having a helical cutting edge which can be used in the manufacturing method of the present invention.

Fig. 3 is a schematic plan view illustrating the difference in cutting direction between a right-hand edge and a left-hand edge of an end mill having a helical cutting edge, which can be used in the manufacturing method of the present invention.

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

Fig. 5 is a schematic perspective view for explaining the cutting process in the manufacturing method of the present invention.

Fig. 6 is a schematic view for explaining the structure of an end mill having a helical cutting edge used for cutting in the manufacturing method of the present invention.

Fig. 7 is a schematic view for explaining the structure of an end mill having an edge angle of 0 ° used for cutting in the manufacturing method of the present invention.

Fig. 8 is a schematic plan view showing an example of the shape of a cut optical laminate with an adhesive layer obtained by the production method of the present invention.

Fig. 9(a) to (c) are schematic plan views illustrating a series of steps of the cutting process in the manufacturing method of the present invention.

Detailed Description

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. Further, the drawings are schematically illustrated for the sake of easy observation, and further, the ratios of the length, width, thickness, and the like, and the angles and the like in the drawings are different from those in reality.

The method for producing an optical laminate with an adhesive layer according to the present invention comprises: forming a work by overlapping a plurality of optical layered bodies with adhesive layers; cutting the outer peripheral surface of the workpiece with an end mill having a helical blade; and further cutting the outer peripheral surface of the cut workpiece by using an end mill having an edge angle of 0 °. The optical laminate with an adhesive layer includes an optical film, an adhesive layer disposed on one side of the optical film, a separator temporarily bonded to the adhesive layer in a peelable manner, and a surface protective film temporarily bonded to the other side of the optical film in a peelable manner. In an embodiment of the present invention, the work is formed by stacking the optical layered body with an adhesive layer so that the spacer is positioned in the chip discharge direction of an end mill having a helical blade. For convenience, first, a specific configuration of the optical laminate with a pressure-sensitive adhesive layer which can be used in the method for producing an optical laminate with a pressure-sensitive adhesive layer of the present invention will be described, and then, a method for producing an optical laminate with a pressure-sensitive adhesive layer of the present invention will be described.

A. Optical laminate with adhesive layer

Fig. 1 is a schematic cross-sectional view 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 illustrated in the drawing includes an optical film 10, an adhesive layer 20, a separator 30, and a surface protection film 40, the adhesive layer 20 being disposed on one side of the optical film 10, the separator 30 being temporarily bonded to the adhesive layer 20 in a peelable manner, and the surface protection film 40 being temporarily bonded to the other side of the optical film 10 in a peelable manner. When the optical laminate with an adhesive layer is applied to an image display device, the separator 30 is typically disposed 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 attach the optical laminate with an adhesive layer to an image display device (substantially, an image display unit). The surface protection film 40 typically has a substrate 41 and an adhesive layer 42. In addition, the pressure-sensitive adhesive layer 42 of the surface protective film may be referred to as a "PF pressure-sensitive adhesive layer" for the sake of distinction from the pressure-sensitive adhesive layer 20. The surface protective film 40 is also peeled off and removed when the optical laminate with the adhesive layer is actually used. In the embodiment of the present invention, by adopting the manufacturing method described below, it is possible to realize a machined optical laminate with a pressure-sensitive adhesive layer in which a surface protective film peeling failure is suppressed. That is, according to the embodiments of the present invention, it is possible to suppress a problem unique to an optical laminate with an adhesive layer including an adhesive layer, a separator, and a surface protective film, that is, a surface protective film peeling failure.

The optical film 10 may be any suitable optical film that can be used for applications requiring cutting (particularly, nonlinear machining). The optical film may be a film composed of a single layer or a laminate. Specific examples of the optical film composed of a single layer include a polarizer and a retardation film. Specific examples of the optical film configured as a laminate include: a polarizing plate (typically a laminate of a polarizer and a protective film), a conductive film for a touch panel, a surface treatment film, and a laminate (for example, an antireflection circularly polarizing plate and a polarizing plate with a conductive layer for a touch panel) obtained by appropriately laminating an optical film composed of these single layers and/or an optical film composed of a laminate according to the purpose.

The pressure-sensitive adhesive layer 20 may have any suitable structure. Specific examples of the adhesive constituting the adhesive layer include: acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the kind, amount, combination and mixing ratio of the monomers forming the base resin of the adhesive, the mixing amount of the crosslinking agent, the reaction temperature, the reaction time and the like, an adhesive having desired characteristics according to the purpose can be prepared. The base resin of the binder may be used alone, or two or more thereof may be used in combination. From the viewpoint of transparency, processability, durability and the like, an acrylic adhesive is preferable. The details of the adhesive constituting the adhesive layer are described in, for example, japanese patent application laid-open No. 2014-115468, the contents of which are incorporated herein by reference. The thickness of the adhesive layer 20 may be, for example, 10 μm to 100 μm. The storage modulus G' of the adhesive layer 20 at 25 ℃ may be, for example, 1.0X 10⁴(Pa)～1.0×10⁶(Pa). The storage modulus can be determined by, for example, dynamic viscoelasticity measurement.

The separator 30 may employ any suitable separator. Specific examples thereof include plastic films, nonwoven fabrics, and papers having surfaces coated with a release agent. Specific examples of the release material include: silicone-based release agents, fluorine-based release agents, and long-chain alkyl acrylate-based release agents. Specific examples of the plastic film include: polyethylene terephthalate (PET) film, polyethylene film, polypropylene film. The thickness of the separator may be, for example, 10 to 100 μm.

As described above, the surface protective film 40 representatively has the base material 41 and the adhesive layer 42. Examples of the material for forming the substrate 41 include: ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene resins, polyamide resins, polycarbonate resins, and copolymer resins thereof. Ester-based resins (particularly polyethylene terephthalate-based resins) are preferred. Such a material has an advantage that the elastic modulus is sufficiently high and the material is not easily deformed even when tension is applied during transportation and/or attachment.

The elastic modulus of the substrate 41 may be, for example, 2.2kN/mm²～4.8kN/mm². When the elastic modulus of the base material is in such a range, there is an advantage that deformation is not easily generated even when tension is applied during transportation and/or bonding. The elastic modulus was measured in accordance with JIS K6781.

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

The pressure-sensitive adhesive layer (PF pressure-sensitive adhesive layer) 42 may have any suitable configuration. Specific examples thereof include: acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the kind, amount, combination and mixing ratio of the monomers forming the base resin of the adhesive, the mixing amount of the crosslinking agent, the reaction temperature, the reaction time and the like, an adhesive having desired characteristics according to the purpose can be prepared. The base resin of the binder may be used alone, or two or more thereof may be used in combination. Constituting PF adhesiveThe adhesive of the layer has the following characteristics: the base resin comprises a polymer having active hydrogen-containing functional groups. As long as such a base resin is used, a PF adhesive layer having a desired storage modulus can be obtained. The details of the adhesive constituting the PF adhesive layer are described in, for example, japanese patent application laid-open No. 2018-123281, the contents of which are incorporated herein by reference. The thickness of the PF adhesive layer 42 may be, for example, 10 to 100 μm. The PF adhesive layer 42 may have a storage modulus G' at 25 ℃ of 0.5 × 10, for example⁶(Pa)～3.0×10⁶(Pa). When the storage modulus is in such a range, a pressure-sensitive adhesive layer (and as a result, a surface protective film) having an excellent balance between adhesiveness and releasability can be obtained. Further, the surface protective film can be warped by the manufacturing method described later, and as a result, stress can be easily concentrated on the peeling point with the warped portion as a grasping edge, and therefore, more excellent peeling property can be achieved while maintaining the allowable adhesiveness.

The thickness of the surface protection film 40 may be, for example, 40 μm to 120 μm. The thickness of the surface protective film is the total thickness of the base material and the PF binder layer.

In one embodiment, the peeling force between the separator 30 and the pressure-sensitive 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 pressure-sensitive adhesive layer 42) (hereinafter also referred to as the peeling force of the surface protective film). In many cases, the surface protective film peeling failure is likely to occur because the peeling force of the surface protective film is larger than that of the separator, but according to the manufacturing method described later, a cut optical laminate with an adhesive layer in which the surface protective film peeling failure is suppressed can be obtained. More specifically, the peeling force of the separator is preferably 0.001N/10mm to 1.0N/10mm, and the peeling force of the surface protective film is preferably 0.01N/10mm to 5.0N/10 mm. The peeling force of the separator is preferably 0.001 to 0.1N/10mm, more preferably 0.005 to 0.03N/10 mm. The peel force of the surface protective film is preferably 0.01 to 0.5N/10mm, and more preferably 0.035 to 0.1N/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 0.01N/10mm to 1.0N/10 mm. According to the production method described later, even if there is such a difference in peeling force, a cut optical laminate with a pressure-sensitive adhesive layer in which surface protective film peeling failure is suppressed can be obtained.

In one embodiment, the thickness of the surface protective film 40 is greater than the thickness of the separator 30. By the manufacturing method described later, even when the thickness of the surface protective film is large and a large peeling force is required as described above, excellent peeling property can be achieved. The difference between the thickness of the surface protective film and the thickness of the separator (thickness of the surface protective film-thickness of the separator) is preferably 5 to 60 μm. According to the manufacturing method described later, even if there is such a difference in thickness, a machined optical laminate with a pressure-sensitive adhesive layer in which surface protection film peeling failure is suppressed can be obtained.

B. Method for producing optical laminate with adhesive layer

Hereinafter, a typical example of a method for producing an optical laminate with an adhesive layer will be described. First, a description will be given of a relationship between a structure of an end mill having a helical cutting edge, which is a characteristic portion of the present invention, and a stacked state of workpieces, and then an outline of a manufacturing method will be described.

B-1 relationship between the constitution of the end mill and the state of lamination of the workpiece

In the embodiment of the present invention, as described above, the optical layered body with the adhesive layer is stacked so that the spacer is positioned in the chip discharge direction of the end mill having the helical blade to form the workpiece, and the outer peripheral surface of the workpiece is cut. The following description will be specifically made with reference to fig. 2 and 3. Fig. 2 is a schematic view illustrating a typical example of the structure of an end mill having a helical cutting edge which can be used in the manufacturing method of the present invention. Fig. 3 is a schematic plan view illustrating the difference in cutting direction between the case where the end mill having the helical cutting edge is a right cutting edge and the case where the end mill has a left cutting edge. As shown in fig. 2, the end mill having the helical cutting edge is roughly divided into a right-hand right helix, a right-hand left helix, a left-hand right helix, and a left-hand left helix. As shown in fig. 2, the right blade means a configuration that can cut when viewed from the upper side (shank side) and rotated clockwise; the left blade is configured to be able to cut when it is rotated counterclockwise as viewed from above (shank side). As further shown in fig. 2, the right helix refers to a configuration in which the cutting edge extends obliquely upward to the right when viewed from the side; the left spiral is a structure in which the blade tip extends obliquely upward to the left when viewed from the side. The discharge direction of the cutting chips of the right-edge right spiral and the left-edge left spiral is upward; the chip discharge direction of the right-hand left-hand spiral and the left-hand right-hand spiral is downward. Further, as shown in fig. 3, the cutting direction of the right blade is typically counterclockwise rotation, and the cutting direction of the left blade is typically clockwise rotation.

In the embodiment of the present invention, as described above, the optical layered body with the adhesive layer is stacked so that the spacer is positioned in the chip discharge direction of the end mill having the helical blade to form the workpiece, and the outer peripheral surface of the workpiece is cut. For example, when the end mill having the helical blade is a right-handed helix or a left-handed helix, the work W is formed by stacking the optical layered bodies with the adhesive layer so that the separator is positioned on the upper side, as shown in fig. 4 (a). On the other hand, when the end mill is a right-handed left-handed or a left-handed right-handed screw, the work W is formed by stacking the optical layered bodies with the adhesive layer so that the spacer is positioned on the lower side, as shown in fig. 4 (b). The present inventors have found that: there are cases where the surface protective film is warped and cases where the warping is not generated, depending on the relationship between the chip discharge direction of an end mill having a helical blade and the arrangement of the surface protective film of the optical laminate with an adhesive layer in the workpiece; further, the problem of poor peeling of the surface protective film can be solved by causing the surface protective film to lift up. With the above-described configuration, the optical laminate with the pressure-sensitive adhesive layer is peeled (or chipped) from the surface protective film side toward the separator side, so that the surface protective film to which a strong cutting force is applied in an oblique direction can be lifted. Thus, a machined optical laminate with an adhesive layer, in which surface protection film peeling failure is suppressed, can be obtained. The amount of lift-off of the surface protective film is preferably 1 μm or more, more preferably 20 μm or more, and still more preferably 50 μm or more. On the other hand, the amount of lift is preferably 1000 μm or less, more preferably 500 μm or less. If the amount of lift-off is within such a range, good peelability of the surface protective film can be achieved while maintaining the appearance quality within an allowable range without causing other problems. Since the occurrence of lifting is avoided as much as possible in the art because lifting degrades the appearance quality, according to the embodiment of the present invention, a machined optical laminate with an adhesive layer in which peeling failure is suppressed can be obtained by positively lifting the surface protective film, which is a technical concept completely deviating from the technical common knowledge in the art. Further, if the relationship between the configuration of the end mill having the helical blade and the stacked state of the workpieces is reversed (that is, if the workpiece is formed as shown in fig. 4(b) in the case where the end mill having the helical blade is a right-handed helix or a left-handed helix and the workpiece is formed as shown in fig. 4(a) in the case where the end mill having the helical blade is a right-handed left-handed helix or a left-handed right-handed helix), the separator is tilted, but the surface protective film is not tilted. As a result, the problem of poor peeling of the surface protective film may not be solved.

B-2. formation of the workpiece

Next, an outline of the cutting process will be described. Fig. 5 is a schematic perspective view for explaining the cutting process in the manufacturing method of the present invention, and this view shows a workpiece W. As shown in fig. 5, a plurality of optical layered bodies with adhesive layers are stacked to form a work W. As described in the section B-1, the stacked state of the workpieces W is set as shown in fig. 4(a) or 4(B) depending on the configuration of the end mill having the helical blade. The optical laminate with the adhesive layer is typically cut into any suitable shape when forming a workpiece. Specifically, the optical laminate with the adhesive layer may be cut into a rectangular shape, a shape close to a rectangular shape, or an appropriate shape (e.g., a circular shape) according to the purpose. The workpiece W has outer peripheral surfaces (cutting surfaces) 1a and 1b facing each other and outer peripheral surfaces (cutting surfaces) 1c and 1d orthogonal to them. The workpiece W is preferably held from above and below by a holding mechanism (not shown). The total thickness of the workpiece is preferably 8mm to 20mm, more preferably 9mm to 15mm, and still more preferably about 10 mm. With such a thickness, it is possible to prevent damage due to pressing by the clamping mechanism or impact during cutting. In the case of an optical laminate with an adhesive layer, the work pieces are superposed to such a total thickness. The number of the optical layered bodies with adhesive layers constituting the work may be, for example, 10 to 50. The clamping mechanism (e.g., a clamp) may be made of a soft material or a hard material. When made of a soft material, the hardness (JISA) is preferably 60 ° to 80 °. If the hardness is too high, there is a case where an impression caused by the clamping mechanism remains. If the hardness is too low, the deformation of the jig may cause positional deviation, and the cutting accuracy may become insufficient.

B-3. cutting

B-3-1. cutting based on end mills with helical edges

Next, the outer peripheral surface of the workpiece W is cut by an end mill 60 having a helical blade. Typically, cutting is performed by bringing a cutting edge of the end mill into contact with the outer peripheral surface of the workpiece W. The cutting may be performed over the entire outer peripheral surface of the workpiece, or may be performed only at a predetermined position.

As shown in fig. 6, the end mill 60 having the helical cutting edge includes a rotation shaft 61 and a cutting edge 62, the rotation shaft 61 extends in the stacking direction (vertical direction) of the workpieces W, and the cutting edge 62 is configured as the outermost diameter of the body that rotates about the rotation shaft 61. In the illustrated example, the cutting edge 62 is formed in an outermost diameter that spirals along the rotation axis 61, and shows a right-handed spiral. The cutting edge 62 includes a tip 62a, a rake surface 62b, and a relief surface 62 c. The number of the cutting edges 62 may be set as appropriate according to the purpose. In the illustrated example, the number of cutting edges is three, but the number of cutting edges may be one continuous cutting edge, two continuous cutting edges, four continuous cutting edges, or five or more continuous cutting edges. The cutting edge angle (helix angle θ of the cutting edge in the illustrated example) of the end mill is preferably 20 ° to 60 °, and more preferably 30 ° to 45 °. If the cutting edge angle is such, the surface protective film can be satisfactorily lifted by cutting. The relief surface of the cutting edge is preferably roughened. Any suitable roughening treatment may be used. A typical example is sand blasting. By roughening the relief surface, the adhesion of the adhesive to the cutting edge can be suppressed, and as a result, blocking can be suppressed. The outer diameter of the end mill is preferably 3mm to 20 mm. In the present specification, "blocking" refers to a phenomenon in which optical layered bodies with an adhesive layer in a work are bonded to each other with an adhesive on end faces, and swarf of the adhesive attached to the end faces contributes to bonding of the optical layered bodies with an adhesive layer to each other. The "outer diameter of the end mill" is a value obtained by multiplying a distance from the rotation axis 61 to the cutting edge 62a by twice. The end mill may be a single-sided fixed end mill with one end (upper end) held, or a double-sided fixed end mill with both ends (upper and lower ends) held.

In the embodiment of the present invention, the cutting by the end mill having the helical blade may correspond to so-called roughing. By first cutting with an end mill having a helical blade and then further cutting (finishing) the cutting surface with an end mill having a cutting edge angle of 0 ° as described later, it is possible to suppress surface protection film peeling failure and to suppress the cutting surface from becoming tapered. The cutting amount by the end mill having the helical blade is preferably about 0.1mm to 0.5 mm.

B-3-2 cutting by means of an end mill with a cutting edge angle of 0 °

In the embodiment of the present invention, after the cutting by the end mill having the helical cutting edge, the cutting surface is further cut by the end mill having the cutting edge angle of 0 ° as shown in fig. 7. This may correspond to a so-called finish cut. With such a configuration, it is possible to suppress the surface protection film from peeling failure and to suppress the cut surface from becoming a tapered shape. More specifically, by cutting in a predetermined manner using an end mill having a helical blade, as described in the above item B-1, the surface protective film is lifted, and a surface protective film peeling failure can be suppressed. On the other hand, although the cutting surface may be tapered in the cutting by an end mill having a helical cutting edge, such a tapered cutting surface can be eliminated by further cutting the cutting surface by an end mill having a cutting edge angle of 0 °. Furthermore, the surface protective film may be warped on the cutting surface side of the optical laminate with an adhesive layer by an end mill having a helical blade, and the appearance quality may be lowered, but such a portion of lowered appearance quality can be removed by cutting with an end mill having a cutting edge angle of 0 °. Further, by cutting with an end mill having an edge angle of 0 °, the amount of lift of the surface protective film generated by cutting with an end mill having a helical edge can be appropriately adjusted. The cutting amount by an end mill having an edge angle of 0 ° is preferably about 0.01mm to 0.2 mm. Cutting by an end mill having an edge angle of 0 ° is finish cutting, and the cutting amount is typically significantly smaller than that by an end mill having a helical edge (cutting amount by rough cutting). Thus, the amount of lift-off of the surface protective film can be appropriately adjusted, and as a result, good peelability of the surface protective film can be achieved while maintaining the appearance quality within an allowable range without causing other problems. Further, the end mill having the helical cutting edge, which is highly versatile, can contribute to most of the cutting, and therefore the manufacturing method of the present invention is advantageous also in terms of cost. In the present specification, the phrase "the cutting edge angle is 0 °" means that the cutting edge 62a extends in a direction substantially parallel to the rotation axis, in other words, the cutting edge is not twisted with respect to the rotation axis. "0 °" means substantially 0 °, and includes slight angular twist due to machining errors and the like. The term "tapered cutting surface" means that the cutting surface extends obliquely from the vertical direction when viewed in the transverse direction.

B-3-3. others

In one embodiment, the manufacturing method of the present invention includes the steps of: the outer peripheral surface of the workpiece is cut non-linearly. The non-linear cutting includes, for example, the following steps as shown in fig. 8: the concave portion 4c including a curved portion is formed in a plan view of the optical laminate with an adhesive layer. In the production of the optical laminate with an adhesive layer in a plan view as shown in fig. 8, the outer periphery of the work is linearly cut, chamfered portions 4a and 4b are formed at two corner portions of the outer periphery of the work, and a recess (a recess including a curved portion) 4c is formed at a central portion of the outer peripheral surface where the chamfered portions 4a and 4b are formed. By forming such a recess, the surface protective film can be lifted up in the vicinity of the recess. As a result, the peelability of the surface protective film when peeled and removed from the recess can be improved. An example of such cutting will be described with reference to fig. 9(a) to 9 (c). First, as shown in fig. 9(a), the portion where the chamfered portion 4a of fig. 8 is formed is chamfered, and then, as shown in fig. 9(b), the portion where the chamfered portion 4b is formed is chamfered. Finally, as shown in fig. 9(c), a recess (a recess including a curved portion) 4c is formed by cutting. The radius of the curved portion is preferably 5mm or less, more preferably 4mm or less, and further preferably 3mm or less. The order of forming the chamfered portions 4a and 4b and the recess 4c (cutting order) is not limited, and they may be formed in any appropriate order.

The cutting conditions may be set as appropriate according to the desired shape. The rotation speeds of the end mill having the helical cutting edge and the end mill having a cutting edge angle of 0 ° are preferably 1000rpm to 60000rpm, and more preferably 10000rpm to 40000rpm, respectively. The feed rates of the end mill having the helical blade and the end mill having a blade angle of 0 ° are preferably 500 mm/min to 10000 mm/min, and more preferably 500 mm/min to 2500 mm/min, respectively. The number of cuts at the cut may be one cut, two cuts, three cuts or more.

In this manner, a cut optical laminate with an adhesive layer can be obtained. The optical laminate with a pressure-sensitive adhesive layer obtained by the production method of the present invention is suppressed in surface protection film peeling failure and is suppressed in taper of the cut surface.

Examples

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Evaluation items of examples are as follows.

(1) Lift-up generation rate of surface protective film

An arbitrary number (preferably 100 or more) of the optical layered bodies with the adhesive layer after the cutting process were prepared, and the lift of the surface protective film was observed using a magnifying glass or a microscope. When the whole periphery of each optical laminate with an adhesive layer was observed and a warpage of 1 μm or more was observed, the optical laminate with an adhesive layer was counted as a sample with a warpage, and the warpage generation rate was calculated from "(sample with warpage/observed number) × 100".

(2) Stripping success rate

50 pieces of the machined optical laminates with pressure-sensitive adhesive layers obtained in examples and comparative examples were randomly extracted, and the surface protective films were peeled off (initial peel force was 2.9N). The number of times of peeling was performed without any problem among 50 peeling was expressed as a percentage, and the success rate of peeling was determined.

(3) Amount of tilting

The amount of lifting of the surface protective film in the optical laminate with an adhesive layer obtained in examples and comparative examples after cutting was measured with a magnifier or a microscope. The maximum value of the amount of lift of one workpiece is taken as the amount of lift.

(4) Cone

The cut surfaces (magnification: 500 times) of the pressure-sensitive adhesive layer-attached polarizing plates obtained in examples and comparative examples were observed from the transverse direction with a Scanning Electron Microscope (SEM). The cut surface as viewed in the lateral direction was evaluated by the following criteria.

O: the cutting surface extends substantially vertically

X: the cutting surface being deviated obliquely from the vertical direction

< example 1 >

An adhesive layer-equipped polarizing plate having a structure of a surface protective film (60 μm)/a cycloolefin protective film (47 μm)/a polarizer (5 μm)/a cycloolefin protective film (24 μm)/an adhesive layer (20 μm)/a separator in this order from the visual confirmation side was obtained by a conventional method. Further, a surface protective film having a constitution of PET substrate (50 μm)/PF adhesive layer (10 μm) was produced as a surface protective film, and verified. In this case, the storage modulus of the pressure-sensitive adhesive layer (pressure-sensitive adhesive) was adjusted to 0.5MPa to 3.0 MPa. The adhesive layer-attached polarizing plate obtained in the above manner was punched out into a size of 5.7 inches (length of about 140mm and width of about 65 mm), and then a plurality of punched-out polarizing plates were overlapped to prepare a workpiece (total thickness of about 10 mm). The obtained work was clamped by a clamping device (jig) and then machined by an end mill to form chamfered portions at two corners of the outer periphery of the work and to form a recess (a recess including a curved portion) at the center of the outer periphery on which the chamfered portions were formed, thereby obtaining a polarizing plate with an adhesive layer which was cut as shown in fig. 8. The cutting was performed twice as rough and as fine. For rough cutting (first cutting), an end mill having a right-hand right helix and a helix angle of 30 ° (discharge direction of chips is upward) was used, and the cut amount was 0.2 mm. For finish cutting (second cutting), an end mill having an edge angle of 0 ° was used, and the cut amount was 0.1 mm. The lift-off generation rate of the surface protection film by cutting was 100%. The obtained polarizing plate with an adhesive layer after cutting was evaluated in the above-mentioned items (2) to (4). The results are shown in Table 1.

< example 2 >

Cutting was performed in the same manner as in example 1, except that an end mill having a right-hand right helix and a helix angle of 45 ° was used for roughing (first 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.

< comparative example 1 >

Cutting was performed in the same manner as in example 1, except that finish cutting (second cutting) was not performed by an end mill having an edge angle of 0 °. 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.

< comparative example 2 >

Cutting was performed in the same manner as in example 2, except that finish cutting (second cutting) was not performed by an end mill having an edge angle of 0 °. 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.

< comparative example 3 >

Cutting was performed in the same manner as in example 1, except that an end mill having an edge angle of 0 ° was used for rough cutting (first cutting) and an end mill having a right-handed right helix and a helix angle of 30 ° was used for finish 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.

< comparative example 4 >

Cutting was performed in the same manner as in example 2, except that an end mill having an edge angle of 0 ° was used for rough cutting (first cutting) and an end mill having a right-handed right helix and a helix angle of 45 ° was used for finish 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.

< comparative example 5 >

Cutting was performed in the same manner as in example 1, except that an end mill having an edge angle of 0 ° was used for both rough cutting (first cutting) and finish 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.

< comparative example 6 >

Cutting was performed in the same manner as in example 1, except that an end mill having a right-hand edge and a right helix and a helix angle of 30 ° was used for both rough cutting (first cutting) and finish 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.

< comparative example 7 >

Cutting was performed in the same manner as in example 1, except that an end mill having a right-hand edge and a right-hand helix and a helix angle of 45 ° was used for both rough cutting (first cutting) and finish 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.

< comparative example 8 >

A cutting process was performed in the same manner as in example 1, except that the work was formed by stacking the adhesive layer-attached polarizing plates such that the separator was located on the lower side. 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.

< comparative example 9 >

A cutting process was performed in the same manner as in example 2, except that the work was formed by stacking the adhesive layer-attached polarizing plates such that the separator was located on the lower side. 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.

TABLE 1

< evaluation >

As can be seen from Table 1: according to an embodiment of the present invention, there is provided a method of manufacturing an optical laminate with an adhesive layer, the method including: the optical laminate with an adhesive layer after cutting is formed by laminating a plurality of optical laminates with an adhesive layer and cutting the outer peripheral surface of the workpiece by using an end mill, wherein the outer peripheral surface is cut by using an end mill having a helical blade, the cutting surface is further cut by using an end mill having a cutting edge angle of 0 DEG, and the optical laminates with an adhesive layer are laminated so that a separator is positioned in the chip discharge direction of the end mill having a helical blade to form a workpiece, and the workpiece thus formed is cut, whereby the optical laminate with an adhesive layer after cutting in which surface protection film peeling failure is suppressed and taper of the cutting surface is suppressed can be simply and inexpensively realized.

Industrial applicability

The production method of the present invention can be suitably used for producing an optical laminate with an adhesive layer which requires cutting (particularly, nonlinear cutting). The optical laminate with an adhesive layer obtained by the production method of the present invention can be suitably used for a profile image display unit represented by an automobile instrument panel and a smart watch.

Description of the symbols

W workpiece

10 optical film

20 adhesive layer

30 divider

40 surface protective film

60 end mill

100 optical laminate with adhesive layer