WO2021192391A1

WO2021192391A1 - Production method for adhesive layer-equipped optical layered body having through-hole

Info

Publication number: WO2021192391A1
Application number: PCT/JP2020/041297
Authority: WO
Inventors: 誠中市; 優樹山本
Original assignee: 日東電工株式会社
Priority date: 2020-03-25
Filing date: 2020-11-05
Publication date: 2021-09-30
Also published as: JPWO2021192391A1; TW202135957A; KR20220156536A; CN115315332A

Abstract

Provided is a method with which can be produced simply and inexpensively, an adhesive layer-equipped optical layered body having a through-hole and for which the loss of glue and the lifting of a separator and of a surface protection film have been suppressed. According to an embodiment of the present invention, the production method for the adhesive layer-equipped optical layered body having a through-hole comprises stacking a plurality of adhesive layer-equipped optical layered bodies to form a workpiece and forming the through-hole at a predetermined position on the workpiece by cutting using an end mill. The adhesive layer-equipped optical layered body comprises an optical film, an adhesive layer disposed on one side of the optical film, a separator adhered temporarily onto the adhesive layer in a releasable manner, and a surface protection film adhered temporarily onto the other side of the optical film in a releasable manner. The formation of the through-hole comprises pressing the end mill against an end surface of the hole and cutting while moving the end mill in either an upward or downward direction to perform the cutting.

Description

Method for manufacturing an optical laminate with an adhesive layer having through holes

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

Various optical laminates (for example, polarizing plates) are used in image display devices such as mobile phones and notebook personal computers in order to realize image display and / or enhance the performance of the image display. .. The optical laminate is typically configured as an optical laminate with an adhesive layer provided with an adhesive layer, and can be bonded to an image display cell. In recent years, with the rapid spread of smartphones and touch panel type information processing devices, image display devices equipped with cameras have come to be widely used. Correspondingly, an optical laminate with an adhesive layer having a through hole at a position corresponding to the camera portion has also been widely used. Such through holes can be formed, for example, by drilling with an end mill.

International Publication No. 2017/047510

However, in the drilling process of the optical laminate with the adhesive layer, so-called glue chipping (a phenomenon in which the edge of the adhesive layer is missing) and / or the floating of the surface protective film and / or the separator used in the manufacturing process occurs. May occur. The present invention has been made to solve such a problem, and its main purpose is to provide an optical laminate with an adhesive layer having through holes in which glue chipping and floating of a surface protective film and a separator are suppressed. It is an object of the present invention to provide a method which can be manufactured easily and inexpensively.

The method for manufacturing an optical laminate with an adhesive layer having through holes according to an embodiment of the present invention is to form a work by stacking a plurality of optical laminates with an adhesive layer and cutting the work using an end mill. Includes forming through holes in place of. The optical laminate with the pressure-sensitive adhesive layer includes an optical film, a pressure-sensitive adhesive layer arranged on one side of the optical film, a separator temporarily attached to the pressure-sensitive adhesive layer so as to be peelable, and the optical film. Includes a surface protective film that is temporarily attached to one side so that it can be peeled off. The formation of the through hole includes cutting by moving the end mill either upward or downward while pressing the end mill against the end face of the hole and cutting.
In one embodiment, the formation of the through hole is to form a pilot hole; while cutting by pressing the end mill against the end face of the pilot hole, the end mill is placed along the end face of the pilot hole. , The end mill is made to go around while moving from a predetermined position at the start of cutting to either the upper side or the lower side to form the next hole having a diameter larger than the diameter of the prepared hole by a predetermined amount; Returning to a predetermined position, the end mill is pressed against the end face of the next hole to cut, and the end mill is moved along the end face of the next hole and the end mill is moved upward or downward from the predetermined position. Making a round while moving to either one to form a further next hole having a diameter larger than the diameter of the next hole by a predetermined amount; and cutting along the end face of the hole by the circumference of the end mill is repeated a predetermined number of times. To form a through hole having a predetermined diameter;
In one embodiment, the formation of the through hole includes forming the pilot hole with a cantilevered end mill and forming a hole after the next hole with a double-sided end mill.
In one embodiment, the end mill has a torsion blade, and the vertical movement direction of the end mill in forming the through hole is a cutting chip discharge direction.
In one embodiment, the end mill forming the prepared hole and the end mill forming the hole after the next hole are the same end mill, and the end mill moves up and down in the formation of the hole after the next hole. The direction is upward.
In one embodiment, the thickness of the work is 10 mm or more.
In one embodiment, the optical film comprises a polarizer or a polarizing plate.

According to an embodiment of the present invention, in the formation of a through hole in the production of an optical laminate with an adhesive layer having a through hole, the end mill is cut while moving either upward or downward to cause glue chipping and It is possible to suppress the floating of the surface protective film and the separator.

It is schematic cross-sectional view explaining an example of the optical laminate with an adhesive layer which can be used in the manufacturing method by Embodiment of this invention. It is schematic cross-sectional view explaining an example of the through hole in the optical laminate with an adhesive layer which can be used in the manufacturing method by Embodiment of this invention. It is schematic cross-sectional view explaining another example of the through hole in the optical laminate with an adhesive layer which can be used in the manufacturing method by Embodiment of this invention. It is a schematic perspective view explaining the outline of the formation of the through hole in the manufacturing method according to the embodiment of this invention. It is a schematic diagram for demonstrating the structure of the end mill which has a torsion blade which can be used for forming a through hole in the manufacturing method by Embodiment of this invention. It is a schematic diagram explaining the relationship between the typical example of the structure of the end mill having a torsion blade which can be used in the manufacturing method by Embodiment of this invention, and the discharge direction and the rotation direction of cutting waste. It is a schematic plan view explaining the details of the formation of the through hole in the manufacturing method according to the embodiment of this invention. (A) is a schematic cross-sectional view for explaining the formation of a pilot hole in the formation of a through hole, and (b) is a schematic cross-sectional view for explaining the formation of holes after the next hole. It is a schematic plan view for demonstrating the cutting by an end mill in the formation of a through hole. (A) is a schematic plan view explaining the trajectory in the plane of the end mill in the formation of the through hole; (b) is a schematic view explaining the upward movement accompanying the movement of the end mill in the plane; (C) is a schematic view explaining the downward movement accompanying the movement of the end mill in a plane. It is the schematic explaining the vertical movement with the movement in the plane of the end mill in the comparative example 4. FIG.

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. The drawings are schematically shown for easy viewing, and the ratios of length, width, thickness, etc., angles, etc. in the drawings are different from the actual ones.

The method for manufacturing an optical laminate with an adhesive layer having through holes according to an embodiment of the present invention is to form a work by stacking a plurality of optical laminates with an adhesive layer and cutting the work by cutting with an end mill. Includes forming through holes in place. The optical laminate with the pressure-sensitive adhesive layer is formed on the optical film, the pressure-sensitive adhesive layer arranged on one side of the optical film, the separator temporarily attached to the pressure-sensitive adhesive layer so as to be peelable, and the other side of the optical film. Includes a surface protective film that is temporarily attached so that it can be peeled off. In embodiments of the present invention, the formation of through holes involves cutting while moving the end mill either upwards or downwards. For convenience, first, a specific configuration of an optical laminate with an adhesive layer that can be used in the manufacturing method according to the embodiment of the present invention will be described, and then an optical laminate with an adhesive layer having a through hole according to the embodiment of the present invention will be described. The method of manufacturing the body 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 according to the embodiment of the present invention. The optical laminate 100 with an adhesive layer of the illustrated example includes an optical film 10, an adhesive layer 20 arranged on one side of the optical film 10, and a separator 30 temporarily attached to the adhesive layer 20 so as to be peelable. , A surface protective film 40 that is temporarily attached to the other side of the optical film 10 so as to be peelable. 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 cell side. In the actual use of the optical laminate with the pressure-sensitive adhesive layer, the separator 30 is peeled off and removed, and the pressure-sensitive adhesive layer 20 is used to bond the optical laminate with the pressure-sensitive adhesive layer to an image display device (substantially, an image display cell). Can be used for. The surface protective film 40 typically has a base material 41 and an adhesive layer 42. In order to distinguish it from the pressure-sensitive adhesive layer 20, the pressure-sensitive adhesive layer 42 of the surface protective film may be referred to as a "PF pressure-sensitive adhesive layer". The surface protective film 40 is also peeled off during actual use of the optical laminate with an adhesive layer.

In the embodiment of the present invention, the optical laminate with the pressure-sensitive adhesive layer has a through hole 50 at a predetermined position. One through hole 50 may be formed as shown in FIG. 2A, two may be formed as shown in FIG. 2B, or three or more through holes 50 may be formed (not shown). For example, when two through holes are formed, they may be formed side by side in the short side direction, may be formed side by side in the long side direction, or may be formed randomly as shown in FIG. 2B. The formation position of the through hole can be appropriately set according to the purpose. The through hole is typically formed at or near the end of the optical laminate with an adhesive layer, and is preferably formed at a corner as shown in the illustrated example. By forming a through hole at or near the end of the optical laminate with an adhesive layer, the influence on the image display when the optical laminate with an adhesive layer is applied to an image display device is minimized. Can be done. In one embodiment, the through hole may be formed at a position corresponding to the camera portion of the image display device. As the plan view shape of the through hole, any suitable shape may be adopted depending on the purpose and the desired configuration of the image display device. A typical example is a substantially circular shape as shown in the illustrated example. The size of the through hole (diameter in the illustrated example) is, for example, 5 mm or less, preferably 1 mm to 5 mm, and more preferably 2 mm to 4 mm. The description of the through hole is omitted in FIG. According to an embodiment of the present invention, in forming a through hole, by cutting while moving the end mill either upward or downward, glue chipping and floating of the surface protective film and the separator are suppressed. can do. That is, according to the embodiment of the present invention, it is possible to solve a peculiar problem in a method for manufacturing an optical laminate with an adhesive layer including an adhesive layer, a separator, and a surface protective film.

Examples of the optical film 10 include any suitable optical film that can be used in applications that require through holes. The optical film may be a film composed of a single layer or a laminated body. 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 polarizing element and a protective film), a conductive film for a touch panel, a surface treatment film, and a single layer thereof. Examples thereof include a laminated body (for example, a circular polarizing plate for antireflection, a polarizing plate with a conductive layer for a touch panel) in which an optical film formed as an optical film and / or an optical film formed as a laminated body is appropriately laminated according to a purpose.

Any suitable configuration can be adopted as the pressure-sensitive adhesive layer 20. Specific examples of the adhesives constituting the adhesive layer include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. Can be mentioned. By adjusting the type, number, combination and blending ratio of the monomers forming the base resin of the pressure-sensitive adhesive, the blending amount of the cross-linking agent, the reaction temperature, the reaction time, etc., the pressure-sensitive adhesive having desired characteristics according to the purpose. Can be prepared. The base resin of the pressure-sensitive adhesive may be used alone or in combination of two or more. An acrylic adhesive is preferable from the viewpoint of transparency, processability, durability and the like. Details of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer are described in, for example, Japanese Patent Application Laid-Open No. 2014-115468, and the description of the publication is incorporated herein by reference. The thickness of the pressure-sensitive adhesive layer 20 can be, for example, 10 μm to 100 μm.

The pressure-sensitive adhesive layer 20 has a creep value at 85 ° C. of, for example, 500 μm or less, preferably 5 μm to 500 μm. In one embodiment, the creep value is preferably 200 μm to 450 μm, more preferably 220 μm to 420 μm. In another embodiment, the creep value is preferably 5 μm to 300 μm, more preferably 5 μm to 200 μm, and even more preferably 10 μm to 100 μm. When the creep value is in such a range, the glue chipping at the time of forming the through hole can be remarkably suppressed, and the peeling in a high temperature and high humidity environment can be remarkably suppressed. Even when the creep value is relatively large (for example, 200 μm or more), the composition of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer (for example, the type of base polymer (polarity, Tg, softness), molecular weight), It is presumed that adhesive chipping can be suppressed by controlling the cross-linked structure (for example, the type of the cross-linking agent, the distance between the cross-linking points (molecular weight between the cross-linking points), the cross-linking density, and the uncross-linked component (sol content)). The creep value can be measured, for example, by the following procedure: a test sample cut out from an optical laminate with an adhesive layer is attached to a support plate at a joint surface of 10 mm × 10 mm. With the support plate to which the test sample is attached fixed, a load of 500 gf is applied vertically downward. The amount of deviation from the support plate after 1 second and 3600 seconds after applying the load is measured and designated as _{Cr 1} _{and Cr 3600} , respectively. Let ΔCr obtained from Cr ₁ and Cr ₃₆₀₀ by the following formula be the creep value.
ΔCr = Cr _3600- Cr ₁

The pressure-sensitive adhesive layer 20 has a storage elastic modulus at 85 ° C. of preferably 1.0 × 10 ⁴ Pa or more, preferably 2.0 × 10 ⁴ Pa or more, and more preferably 5.0 × 10 ⁴ Pa or more. or more, further preferably 1.0 × ¹⁰ 5 Pa or more. When the storage elastic modulus is in such a range, it becomes easy to realize the desired creep value. On the other hand, the storage modulus is less for example 3.0 × ¹⁰ 6 Pa. The storage elastic modulus can be obtained from, for example, dynamic viscoelasticity measurement.

As the separator 30, any suitable separator can be adopted. Specific examples include plastic films, non-woven fabrics or paper surface-coated with a release agent. Specific examples of the release material include a silicone-based release agent, a fluorine-based release agent, and a long-chain alkyl acrylate-based release agent. Specific examples of the plastic film include polyethylene terephthalate (PET) film, polyethylene film, and polypropylene film. The thickness of the separator can be, for example, 10 μm to 100 μm.

As described above, the surface protective film 40 typically has a base material 41 and an adhesive layer 42. Examples of the material for forming the base material 41 include ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, and their common weights. Combined resin can be mentioned. An ester resin (particularly, a polyethylene terephthalate resin) is preferable. Such a material has an advantage that the elastic modulus is sufficiently high and deformation is unlikely to occur even if tension is applied during transportation and / or bonding.

The elastic modulus of the base material 41 can be, for example, 2.2 kN / mm ² to 4.8 kN / mm ² . When the elastic modulus of the base material is within such a range, there is an advantage that deformation is unlikely to occur even if tension is applied during transportation and / or bonding. The elastic modulus is measured according to JIS K 6781.

The thickness of the base material 41 can be, for example, 30 μm to 70 μm.

Any suitable configuration can be adopted as the pressure-sensitive adhesive layer (PF pressure-sensitive adhesive layer) 42. Specific examples include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the type, number, combination and blending ratio of the monomers forming the base resin of the pressure-sensitive adhesive, the blending amount of the cross-linking agent, the reaction temperature, the reaction time, etc., the pressure-sensitive adhesive having desired characteristics according to the purpose. Can be prepared. The base resin of the pressure-sensitive adhesive may be used alone or in combination of two or more. The pressure-sensitive adhesive constituting the PF pressure-sensitive adhesive layer is characterized in that the base resin contains a polymer having an active hydrogen-containing functional group. With such a base resin, a PF pressure-sensitive adhesive layer having a desired storage elastic modulus can be obtained. Details of the pressure-sensitive adhesive constituting the PF pressure-sensitive adhesive layer are described in, for example, JP-A-2018-123281, and the description of the publication is incorporated herein by reference. The thickness of the PF pressure-sensitive adhesive layer 42 can be, for example, 10 μm to 100 μm. The storage elastic modulus G'of the PF pressure-sensitive adhesive layer 42 at 25 ° C. can be, for example, 0.5 × 10 ⁶ (Pa) to 3.0 × 10 ⁶ (Pa). When the storage elastic modulus is in such a range, an adhesive layer (as a result, a surface protective film) having an excellent balance between adhesiveness and peelability can be obtained.

The thickness of the surface protective film 40 can be, for example, 40 μm to 120 μm. The thickness of the surface protective film means the total thickness of the base material and the PF adhesive layer.

B. Method for Manufacturing Optical Laminate with Adhesive Layer Hereinafter, a typical example of the method for manufacturing an optical laminate with a pressure-sensitive adhesive layer will be described.

B-1. Work formation First, the work is formed. FIG. 3 is a schematic perspective view illustrating the outline of formation of a through hole in the manufacturing method according to the embodiment of the present invention, and the work W is shown in this figure. As shown in FIG. 3, a work W in which a plurality of optical laminates with an adhesive layer are laminated is formed. The optical laminate with the pressure-sensitive adhesive layer is typically cut into an arbitrary suitable shape when the work is formed. Specifically, the optical laminate with the adhesive layer may be cut into a rectangular shape, may be cut into a shape similar to the rectangular shape, and may be cut into an appropriate shape (for example, a circle) according to the purpose. It may be disconnected. In one embodiment, the work 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 work W is preferably clamped from above and below by clamping means (not shown). The total thickness of the work is preferably 3 mm or more, more preferably 5 mm to 40 mm, and further preferably 10 mm to 30 mm. For example, when the diameter of the through hole is 2 mm to 3 mm, the total thickness of the work is preferably 10 mm to 25 mm. According to the embodiment of the present invention, in forming a through hole, the total thickness of the work can be increased by cutting while moving the end mill either upward or downward. As a result, the manufacturing efficiency of the optical laminate with the pressure-sensitive adhesive layer having through holes can be remarkably improved. The optical laminate with the pressure-sensitive adhesive layer is laminated so that the workpieces have such a total thickness. The number of optical laminates with an adhesive layer constituting the work can vary depending on the thickness of the optical laminate with an adhesive layer. The number of optical laminates with an adhesive layer is preferably 50 or more, more preferably 50 to 200, and even more preferably 75 to 150. According to the embodiment of the present invention, a work can be formed by stacking a significantly larger number of optical laminates with an adhesive layer than usual, and as a result, the optical laminate with an adhesive layer having through holes can be formed. The production efficiency can be remarkably improved. The clamping means (for example, a jig) may be made of a soft material or a hard material. When composed of a soft material, its hardness (JIS A) is preferably 60 ° to 80 °. If the hardness is too high, imprints may remain due to the clamping means. If the hardness is too low, the jig may be deformed and misaligned, resulting in insufficient cutting accuracy.

B-2. Formation of through holes Next, through holes are formed in the work (substantially, an optical laminate with an adhesive layer). The through hole can be formed by cutting with an end mill as shown in FIG. In addition, in FIG. 3, the pilot hole formed first and the through hole finally formed are schematically shown. Hereinafter, the end mill that can be used for forming the through hole will be described first, and then the specific procedure for forming the through hole will be described.

B-2-1. Configuration of End Mill The end mill 60 may have a twisted blade (may have a predetermined blade angle) or may have a blade angle of 0 °. The end mill 60 typically has a torsion blade as shown in FIGS. 3 and 4. By using an end mill having a twisted blade, the effect of cutting while moving the end mill either upward or downward (described later) becomes remarkable. This is because it is easy to match the direction of cutting chips with the direction of movement of the end mill. As shown in FIG. 4, the end mill 60 having a torsion blade has a rotating shaft 61 extending in the stacking direction (vertical direction) of the work W and a cutting blade configured as the outermost diameter of a main body rotating around the rotating shaft 61. 62 and. In the illustrated example, the cutting blade 62 is configured as the outermost diameter twisted along the rotating shaft 61, and shows a right-handed right-handed twist. The cutting blade 62 includes a cutting edge 62a, a rake surface 62b, and a relief surface 62c. The number of cutting blades 62 can be appropriately set according to the purpose. The cutting blade in the illustrated example has a configuration of three blades, but the number of blades may be one continuous blade, two blades, four blades, or five or more blades. good. The blade angle of the end mill (the helix angle θ of the cutting blade in the illustrated example) is preferably 10 ° to 40 °, more preferably 20 ° to 30 °. The rake angle is preferably 15 ° to 25 °, and the clearance angle is preferably 25 ° to 35 °. The relief surface of the cutting blade is preferably roughened. As the roughening treatment, any appropriate treatment can be adopted. A typical example is blasting. By applying the roughening treatment to the relief surface, the adhesion of the adhesive to the cutting blade can be suppressed, and as a result, blocking can be suppressed. The outer diameter of the end mill is preferably 0.5 mm to 10 mm, more preferably 0.8 mm to 5 mm, and even more preferably 1 mm to 3 mm. The effective length of the cutting blade of the end mill is preferably 10 mm to 50 mm, more preferably 20 mm to 40 mm. In the present specification, "blocking" refers to a phenomenon in which optical laminates with an adhesive layer adhere to each other with an adhesive on the end face, and the shavings of the adhesive adhering to the end face are the optical laminate with the adhesive layer. It will contribute to the adhesion between the bodies. Further, the "outer diameter of the end mill" means that the distance from the rotating shaft 61 to the cutting edge 62a is doubled.

Next, the relationship between the configuration of the end mill and the direction of discharge and rotation of cutting chips will be explained. FIG. 5 is a schematic view illustrating a typical example of the configuration of an end mill having a torsion blade that can be used in the manufacturing method according to the embodiment of the present invention. As shown in FIG. 5, the configuration of an end mill having a twisted blade is roughly classified into a right-handed right-handed twist, a right-handed left-handed twist, a left-handed right-handed twist, and a left-handed left-handed twist. As shown in FIG. 5, the right blade means a configuration that can be cut when rotated clockwise when viewed from the upper side (shank side); and the left blade means a counterclockwise direction when viewed from the upper side (shank side). A configuration that can be cut when rotated to. As further shown in FIG. 5, right-handed twist refers to a configuration in which the cutting edge extends diagonally upward to the right when viewed from the side; and left-handed twist refers to a configuration in which the cutting edge extends diagonally upward to the left when viewed from the side. Right-blade right-handed and left-blade left-handed twists have a cutting chip discharge direction upward; right-blade left-handed twist and left-blade right-handed twist have a cutting waste discharge direction downward.

B-2-2. Formation of Through Holes Hereinafter, typical examples of formation of through holes using the above-mentioned end mill will be described with reference to FIGS. 6 to 9.

First, as shown in FIG. 6, a pilot hole 51 is formed. As used herein, the term "prepared hole" refers to a hole that serves as a clue for forming a through hole at a correct position. The pilot hole 51 can be typically formed by an end mill 60 in a cantilever state (a state in which only one end is held), as shown in FIG. 7A. In the illustrated example, the end mill 60 holding the upper end is moved from the upper side to the lower side to form the pilot hole 51, but the end mill 60 holding the lower end may be moved from the lower side to the upper side to form the pilot hole 51. .. The diameter of the prepared hole 51 is substantially the same as the outer diameter of the end mill 60.

Next, as shown in FIG. 8, the end mill 60 is pressed against the end face of the prepared hole 51 to cut, and the end mill 60 is made to go around along the end face of the prepared hole 51. As a result, as shown in FIGS. 6 and 8, the next hole 52 having a diameter P larger than the diameter of the prepared hole 51 by a predetermined amount P is formed. In the embodiment of the present invention, the end mill 60 is moved around the end face of the prepared hole 51 while moving from a predetermined position A at the start of cutting to either the upper side or the lower side to form the next hole 52. As an example, as shown in FIG. 9 (a), starting from the cutting starting position A _S of the prepared hole 51 will be described the case of forming the next hole 52. In this case, the end mill 60 is outermost (cutting edge) is while cutting the end surface of the prepared hole 51, moves _{_{_{A S → A 1 → A 2}}} → A 3 → A 4 → A 1 → A S. Specifically, A _S → A ₁ starts cutting a predetermined pitch and moves along the orbit clockwise when viewed from above end mill, then, the end mill along the end face of the prepared hole 51 A ₁ → A ₂ → A ₃ → A ₄ → A ₁ goes around. _{When it reaches A 1} after making one lap, the end mill returns to As while cutting in a clockwise trajectory when viewed from above. Here, the end mill 60 (e.g., the midpoint M of the cutting edge as a positioning indicator) when is in a predetermined position T in the thickness direction of the work (the vertical direction), end mill _{_{_{A S → A 1 → A 2}}} → A 3 → as it moves with _{_{_{a 4 → a 1 → a S}}} , the position of the end mill, the figure in the case when moving the end mill upward changes as in FIG. 9 (b), to move the end mill downward It changes as in 9 (c). When one round cutting to the next hole 52 is formed at the position A _S, the end mill 60 is returned to the position T (this time, the cutting is not performed). In this specification, the predetermined amount P may be referred to as a cutting pitch.

Then, the end mill 60 from the position A _S, (no cutting between the mobile is performed) to further moved to the horizontal direction to the cutting start position B _S of the next hole 53. The following procedure is similar to the cutting of the pilot hole (formation of the next hole 52), and the end mill 60 is moved to either the upper side or the lower side to make a circuit along the end face of the next hole 52, and then the next hole is formed. Cut the end face of 52. As a result, as shown in FIG. 6, a further next hole 53 having a diameter P larger than the diameter of the next hole 52 by a predetermined amount P is formed. More specifically, as shown in FIG. 9 (a), the end mill 60, while the outermost (cutting edge) of cutting the end face of the next hole _{_{52, B S → B 1 →}} B 2 → B 3 → B 4 → B ₁ → B _S. Accordance end mill is moved _{_{_{B S → B 1 → B 2}}} → B 3 → B 4 → B 1 → B S, the position of the end mill, in the case of moving the end mill upward as shown in FIG. 9 (b) When it changes and the end mill is moved downward, it changes as shown in FIG. 9 (c). Further next hole 53 by one round cutting is formed at a position B _S, the end mill 60 is returned to the position T. Then, the end mill 60 from the position B _S, further moved in the horizontal direction to the cutting start position C _S of the next hole, by repeating the same procedure, to form a through-hole having a desired diameter.

The amount of movement of the end mill upward or downward in the formation of the through hole (U in FIG. 9B or D in FIG. 9C) is preferably 1 mm to 8 mm, more preferably 2 mm to 7 mm. More preferably, it is 3 mm to 5 mm. If the amount of movement is too small, chipping of glue or floating of the surface protective film or separator may not be sufficiently suppressed. The larger the amount of movement, the more preferable, and the upper limit can be limited by the effective length of the cutting blade of the end mill. The amount of movement can be, for example, 6% to 15% with respect to the effective length of the cutting blade of the end mill.

The moving direction of the end mill is preferably the direction of discharging cutting chips. That is, if the end mill is right-blade right-handed or left-blade left-handed, the direction of movement is upward; if the end mill is right-blade left-handed or left-blade right-handed, the direction of movement is downward. With such a configuration, the accumulation of cutting chips on the cutting edge of the rake face is remarkably suppressed, and the cutting chips are discharged extremely well. Alternatively, the pushing into the separator is remarkably suppressed, and as a result, the adhesive chipping and the floating of the surface protective film and the separator can be remarkably suppressed.

In one embodiment, it is preferable to blow air from the side opposite to the discharge side of the cutting chips in the discharge direction in the formation of the through hole (cutting process). With such a configuration, cutting chips are discharged more satisfactorily, so that glue chipping and floating of the surface protective film and separator can be further suppressed. The blowing pressure is, for example, 0.05Mpa to 1Mpa, the wind speed is, for example, 1,500 m / min to 15,000 m / min, and the air volume is, for example, 5 L / min to 1,000 L / min.

The holes after the next hole 52 can be typically formed by an end mill 60 in a double-sided state (a state in which both ends are held), as shown in FIG. 7 (b).

The end mill used for forming the next hole 52 and subsequent holes (hereinafter, may be referred to as cutting by orbit) may be the same as or different from the end mill used for forming the prepared hole 51. When the end mill used for the orbital cutting is the same as the end mill used for forming the pilot hole, the vertical movement direction of the end mill in the orbital cutting is preferably upward. More specifically, the pilot hole can be formed by moving the end mill in the cantilever state (holding the upper end) downward, as described above. In this case, the direction of discharging cutting chips is preferably upward from the viewpoint of suppressing adhesive chipping and floating of the surface protective film and the separator. Therefore, it is preferable that the vertical movement direction of the end mill in cutting by orbit is upward, which is the discharge direction of cutting chips. If the end mill used for orbital cutting is different from the end mill used for forming pilot holes, the vertical movement direction of the end mill during orbital cutting is upward corresponding to the end mill configuration (cutting waste discharge direction). It may be lower or lower.

The cutting pitch P can change according to the size of the through hole, the outer diameter of the end mill, and the number of turns of the end mill. The number of turns of the end mill can change depending on the size of the through hole, the outer diameter of the end mill, and the cutting pitch P. The cutting pitch is, for example, 5 μm to 20 μm, preferably 5 μm to 10 μm. For example, when the size of the through hole is 3 mm, the outer diameter of the end mill is 2 mm, and the cutting pitch P is 10 μm, the number of laps of the end mill is 50 times.

The cutting conditions for forming the through hole can be appropriately set according to the size of the through hole, the outer diameter of the end mill, the number of laps of the end mill, and the like. The rotation speed of the end mill is preferably 1000 rpm to 10000 rpm, and more preferably 1500 rpm to 4000 rpm. The feed rate of the end mill is preferably 50 mm / min to 2000 mm / min, more preferably 70 mm / min to 1000 mm / min, and even more preferably 70 mm / min to 400 mm / min.

By repeating the cutting along the end face of the hole by the end mill as described above (that is, by performing the cutting by the end mill a predetermined number of times), a through hole 50 having a predetermined diameter is formed. If necessary, the end face of the through hole may be subjected to finish cutting.

As described above, an optical laminate with an adhesive layer having through holes can be obtained. In the optical laminate with an adhesive layer that can be obtained by the production method according to the embodiment of the present invention, adhesive chipping and floating of the surface protective film and the separator are suppressed.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The evaluation items in the examples are as follows.

(1) Adhesive chipping Ten optical laminates with an adhesive layer were extracted from the work of the optical laminate with an adhesive layer having through holes obtained in Examples and Comparative Examples. The 10 optical laminates with an adhesive layer are one from the top and bottom optical laminates of the work, and one from the upper part and the lower part of the work divided into five in the thickness direction. , And two optical laminates with an adhesive layer randomly extracted from each of the three central portions. For the 10 optical laminates with an adhesive layer, observe the glue chipping in the through-hole portion using a loupe or a microscope, and if no adhesive chipping of 50 μm or more is observed, the optical laminate with an adhesive layer is It was counted as a "no glue chipping" sample. The ratio (%) of the "no glue chipping" sample out of 10 was used as the evaluation standard. For Example 5 and Comparative Example 3, 50 sets of workpieces were prepared and a total of 500 samples were evaluated.
A: "No glue chipping" sample is 90% or more B: "No adhesive chipping" sample is 60% or more and less than 90% C: "No adhesive chipping" sample is less than 60% (2) Floating surface protection film or separator In the same manner as in (1), the floating of the surface protective film or separator in the through hole portion was observed, and if no floating of 50 μm or more was observed, the optical laminate with the adhesive layer was counted as a “no floating” sample. The ratio (%) of the "no float" sample out of 10 was used as the evaluation standard. For Example 5 and Comparative Example 3, 50 sets of workpieces were prepared and a total of 500 samples were evaluated.
A: "No float" sample is 98% or more B: "No float" sample is 60% or more and less than 98% C: "No float" sample is less than 60% (3) Crack Similar to (1) above The cracks in the portion were observed, and if no cracks of 50 μm or more were observed, the optical laminate with the adhesive layer was counted as a “crack-free” sample. The ratio (%) of "no crack" samples out of 10 was used as the evaluation standard. For Example 5 and Comparative Example 3, 50 sets of workpieces were prepared and a total of 500 samples were evaluated.
A: "No crack" sample is 98% or more B: "No crack" sample is 60% or more and less than 98% C: "No crack" sample is less than 60%

<Example 1>
Polarized light with an adhesive layer having a structure of a surface protective film (58 μm) / HC-TAC protective film (32 μm) / polarizer (5 μm) / adhesive layer (15 μm) / separator (38 μm) in order from the visual side by a conventional method. A plate was made. The HC-TAC protective film is a film in which a hard coat (HC) layer (7 μm) is formed on a triacetyl cellulose (TAC) film (25 μm), and the TAC film is laminated so as to be on the polarizer side. As the surface protective film, a surface protective film having a composition of PET base material (38 μm) / PF pressure-sensitive adhesive layer (20 μm) was used. The creep value of the pressure-sensitive adhesive layer was 73 μm. The obtained polarizing plate with an adhesive layer was punched to a size of 5.7 inches (length 140 mm and width 65 mm), and 120 punched polarizing plates were stacked to form a work (total thickness about 18 mm). With the obtained work sandwiched between clamps (jigs), a through hole having a diameter of 3 mm was formed at a corner by end milling. More details were as follows. The end mill used to form the through hole has an outer diameter of 2.0 mm, an effective length of the cutting blade of 30 mm, a blade angle of 25 °, a rake angle of 20 °, a clearance angle of 30 °, and a right-handed twist of the cutting blade (cutting waste discharge direction is Above). Using this end mill, first, a pilot hole (diameter 2 μm) was formed by moving it downward from the surface protective film side (upper side) in a cantilevered state. Next, the end mill was held in a double-sided state, and as shown in FIG. 9A, the end mill was pressed against the end face of the pilot hole to cut the end mill, and the end mill was made to go around along the end face of the pilot hole. The cutting pitch was 10 μm. In this embodiment, the end mill was rotated once and moved upward by 4 mm. After circulation, after returning the end mill A _S position, by 4mm moved downward (i.e., by 4mm moved downward in a state that does not cut) was returned to the original position in the vertical direction. Then, the end mill is moved from A _S to B _S, it was cut by next lap of the end mill. By repeating such cutting by orbiting the end mill, a through hole having a diameter of 3 mm was formed. The horizontal movement speed of the end mill in the orbit was 250 mm / min, and the rotation speed was 2500 rpm. The obtained polarizing plates with an adhesive layer having through holes were evaluated in (1) to (3) above. The results are shown in Table 1.

<Example 2>
A polarizing plate with an adhesive layer having a through hole was produced in the same manner as in Example 1 except that the cutting process was performed by orbiting the end mill in a cantilevered state. The obtained polarizing plate with an adhesive layer having through holes was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Comparative example 1>
A polarizing plate with an adhesive layer having through holes was produced in the same manner as in Example 1 except that the end mill was not moved upward (moved only in the horizontal direction) in the cutting process by rotating the end mill. The obtained polarizing plate with an adhesive layer having through holes was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Comparative example 2>
A polarizing plate with an adhesive layer having a through hole was produced in the same manner as in Example 2 except that the end mill was not moved upward (moved only in the horizontal direction) in the cutting process by rotating the end mill. The obtained polarizing plate with an adhesive layer having through holes was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 3>
By the conventional method, the surface protective film (58 μm) / HC-TAC protective film (32 μm) / polarizer (12 μm) / TAC protective film (25 μm) / adhesive layer (1 μm) / first retardation layer in order from the visual side. A circularly polarizing plate with an adhesive layer having a structure of (thickness 2.5 μm) / adhesive layer (5 μm) / second retardation layer (thickness 1.5 μm) / adhesive layer (20 μm) / separator (38 μm). Made. Both the first retardation layer and the second retardation layer are orientation-solidified layers of liquid crystal compounds, the in-plane retardation of the first retardation layer is 240 nm, and the in-plane retardation of the second retardation layer is in-plane. The phase difference was 120 nm. Further, the angle formed by the slow axis of the first retardation layer and the absorption axis of the polarizer is 15 °, and the angle formed by the slow axis of the second retardation layer and the absorption axis of the polarizer is 75 °. It was °. The creep value of the pressure-sensitive adhesive layer was 73 μm. The obtained polarizing plate with an adhesive layer was punched to a size of 5.7 inches (length 140 mm and width 65 mm), and 90 punched polarizing plates were stacked to form a work (total thickness about 18 mm). Hereinafter, a circularly polarizing plate with an adhesive layer having a through hole was produced in the same manner as in Example 1 except that the moving speed in the horizontal direction in the circumference of the end mill was 70 mm / min. The obtained circularly polarizing plate with an adhesive layer having through holes was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 4>
A circularly polarizing plate with an adhesive layer having a through hole was produced in the same manner as in Example 3 except that the horizontal moving speed in the circumference of the end mill was 125 mm / min. The obtained circularly polarizing plate with an adhesive layer having through holes was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 5>
A circularly polarizing plate with an adhesive layer having a through hole was produced in the same manner as in Example 3 except that the horizontal moving speed in the circumference of the end mill was 250 mm / min. The obtained circularly polarizing plate with an adhesive layer having through holes was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Comparative example 3>
Same as in Example 5 except that the end mill was not moved upward (moved only in the horizontal direction) in the cutting process by the circuit of the end mill and the cutting process by the circuit of the end mill was performed in a cantilever state. A circularly polarizing plate with an adhesive layer having a through hole was produced. The obtained circularly polarizing plate with an adhesive layer having through holes was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Comparative example 4>
In the cutting process by rotating the end mill, the end mill was moved in the vertical direction like a sine curve as shown in FIG. Specifically, the end mill was moved by 2 mm in the vertical direction while making one round. Except for this, a circularly polarizing plate with an adhesive layer having through holes was produced in the same manner as in Comparative Example 3. The obtained circularly polarizing plate with an adhesive layer having through holes was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Evaluation>
As is clear from Table 1, according to the embodiment of the present invention, by moving the end mill either upward or downward during the orbiting of the end mill in the formation of the through hole of the optical laminate with the adhesive layer. , Glue chipping and floating of the surface protective film or separator can be remarkably suppressed.

The manufacturing method of the present invention can be suitably used for manufacturing an optical laminate with an adhesive layer that requires a through hole. The optical laminate with an adhesive layer obtained by the manufacturing method of the present invention is suitably used for an image display unit having a through hole represented by an automobile instrument panel, a smart watch, and an image display device having a camera unit. obtain.

W work 10 Optical film 20 Adhesive layer 30 Separator 40 Surface protection film 60 End mill 100 Optical laminate with adhesive layer

Claims

Forming a work by stacking a plurality of optical laminates with an adhesive layer, and forming a through hole at a predetermined position of the work by cutting with an end mill.
Including
The optical laminate with the pressure-sensitive adhesive layer includes an optical film, a pressure-sensitive adhesive layer arranged on one side of the optical film, a separator temporarily attached to the pressure-sensitive adhesive layer so as to be peelable, and the optical film. Includes a peelable surface protective film on one side,
The formation of the through hole involves moving the end mill either upward or downward while cutting by pressing the end mill against the end face of the hole.
A method for manufacturing an optical laminate with an adhesive layer having through holes.
The formation of the through hole
Forming a pilot hole;
While cutting by pressing the end mill against the end face of the prepared hole, move the end mill along the end face of the prepared hole and move the end mill either upward or downward from a predetermined position at the start of cutting. To form the next hole having a diameter larger than the diameter of the prepared hole by a predetermined amount;
While returning the end mill to the predetermined position and pressing the end mill against the end face of the next hole for cutting, the end mill is moved along the end face of the next hole and the end mill is moved from the predetermined position. Making a round while moving it either upward or downward to form a further hole having a diameter that is a predetermined amount larger than the diameter of the next hole;
Cutting along the end face of the hole by orbiting the end mill is repeated a predetermined number of times to form a through hole having a predetermined diameter;
The manufacturing method according to claim 1.
The production according to claim 2, wherein the formation of the through hole includes forming the pilot hole with a cantilevered end mill and forming a hole after the next hole with a double-sided end mill. Method.
The manufacturing method according to any one of claims 1 to 3, wherein the end mill has a torsion blade, and the vertical movement direction of the end mill in forming the through hole is a cutting waste discharge direction.
A claim that the end mill forming the prepared hole and the end mill forming the hole after the next hole are the same end mill, and the vertical movement direction of the end mill in forming the hole after the next hole is upward. Item 8. The production method according to any one of Items 2 to 4.
The manufacturing method according to any one of claims 1 to 5, wherein the thickness of the work is 10 mm or more.
The production method according to any one of claims 1 to 6, wherein the optical film includes a polarizer or a polarizing plate.