CN117980099A

CN117980099A - Method for producing optical laminate with adhesive layer

Info

Publication number: CN117980099A
Application number: CN202280063709.9A
Authority: CN
Inventors: 松山裕纪; 村永佳奈子
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2021-09-21
Filing date: 2022-06-23
Publication date: 2024-05-03
Also published as: JP7312221B2; KR20240072120A; TW202332532A; JP2023044997A; JP2023090712A; WO2023047731A1

Abstract

The invention provides a simple method for manufacturing an optical laminate with an adhesive layer, wherein the warping of a release liner is suppressed. The method for producing an optical laminate with an adhesive layer according to an embodiment of the present invention includes: alternately overlapping the optical laminated body with the adhesive layers and the intermediate films to form a workpiece; and cutting the outer peripheral surface of the workpiece. In one embodiment, an optical stack with an adhesive layer comprises: an optical film; a first adhesive layer which is arranged on one side of the optical film and has a thickness of 50 [ mu ] m or more; a first release liner releasably temporarily adhered to the first adhesive layer; a second adhesive layer disposed on the other side of the optical film; and a second release liner releasably temporarily attached to the second adhesive layer.

Description

Method for producing optical laminate with adhesive layer

Technical Field

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

Background

Various optical laminates (e.g., polarizing plates) are used in image display devices such as mobile phones and notebook personal computers in order to realize image display and/or to improve the performance of the image display. Typically, an adhesive layer for bonding a front panel (e.g., cover glass) is provided as an outermost layer on one side of the optical laminate, and another adhesive layer for bonding the optical laminate to an image display panel is provided as an outermost layer on the other side. In actual use, a release liner is temporarily attached to the adhesive layers so as to be releasable, and the adhesive layers are protected during the period before actual use. 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.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2001-54845

Disclosure of Invention

Technical problem to be solved by the invention

However, in the end face cutting process of the optical laminate with the adhesive layer, there is a case where the temporarily attached release liner is lifted. The present invention has been made to solve the above-described problems, and a main object of the present invention is to provide a simple method for producing an optical laminate with an adhesive layer, which suppresses the lift-up of a release liner.

Technical scheme for solving technical problems

The method for producing an optical laminate with an adhesive layer according to an embodiment of the present invention includes: alternately overlapping the optical laminated body with the adhesive layers and the intermediate films to form a workpiece; and cutting the outer peripheral surface of the workpiece.

In one embodiment, the thickness of the intermediate film is 75 μm to 1000 μm.

In one embodiment, the intermediate film is made of a polyester resin.

In one embodiment, the optical laminate with an adhesive layer includes: an optical film; a first adhesive layer which is arranged on one side of the optical film and has a thickness of 50 [ mu ] m or more; a first release liner releasably temporarily attached to the first adhesive layer; a second adhesive layer disposed on the other side of the optical film; a second release liner releasably temporarily attached to the second adhesive layer; the first release liner has a release force greater than the release force of the second release liner. In one embodiment, the optical film includes a polarizing plate and a retardation layer in this order from the first adhesive layer side.

In one embodiment, the cutting of the workpiece includes: cutting by an end mill.

In one embodiment, the end mill has helical cutting edges, and the chip flute area of each cutting edge is 5mm ² or more.

In one embodiment, the end mill has an outer diameter of 10mm to 20mm.

In one embodiment, the cutting by the end mill includes: cutting with a helical file.

In one embodiment, the cutting by the end mill includes: rough cutting with an end mill having a helical blade, and finish cutting with a helical file.

Effects of the invention

According to the embodiment of the present invention, by alternately stacking the plurality of adhesive layer-attached optical laminates and the plurality of intermediate films to form a work and cutting the outer peripheral surface of the work, a simple method for manufacturing the adhesive layer-attached optical laminate can be realized in which the lift-up of the release liner is suppressed.

Drawings

Fig. 1 is a schematic front view of a main part of a method for forming a workpiece in a manufacturing method according to an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view illustrating an example of an optical laminate with an adhesive layer that can be used in the method for manufacturing an optical laminate according to the embodiment of the present invention.

Fig. 3 is a schematic perspective view illustrating the outline of the cutting process in the manufacturing method according to the embodiment of the present invention.

Fig. 4 is a schematic perspective view for explaining the structure of an end mill having a helical blade that can be used for cutting in the manufacturing method according to the embodiment of the present invention.

Fig. 5 is a schematic plan view, as viewed from the rotation axis direction, of the chip flute area of an end mill having a helical blade that can be used for cutting in the manufacturing method according to the embodiment of the present invention.

Fig. 6 is a schematic perspective view for explaining the structure of a helical file which can be used for end face processing in the manufacturing method according to the embodiment of the present invention.

Fig. 7 is a schematic view of a helical file having no relief angle in an embodiment of a manufacturing method according to an embodiment of the present invention.

Fig. 8 is a schematic cross-sectional view of a main portion for explaining the depth of concavity and convexity and the pitch of the file body in the helical file of fig. 6.

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. In addition, the drawings are schematically shown for easy viewing, and ratios of length, thickness, and the like, and angles and the like in the drawings are different from actual ones.

The method for producing an optical laminate with an adhesive layer according to an embodiment of the present invention includes: alternately overlapping the optical laminated body with the adhesive layers and the intermediate films to form a workpiece; and cutting the outer peripheral surface of the workpiece. In the embodiment of the present invention, the optical laminate with adhesive layers and the plurality of intermediate films are alternately stacked to form a work, whereby the optical laminate with adhesive layers, in which the lift-up of the release liner is suppressed (as a result, the occurrence of defects in the adhesive layers is suppressed), can be easily realized. The adhesive layer-attached optical laminate typically comprises: an optical film; a first adhesive layer which is arranged on one side of the optical film and has a thickness of 50 [ mu ] m or more; a first release liner releasably temporarily adhered to the first adhesive layer; a second adhesive layer disposed on the other side of the optical film; and a second release liner releasably temporarily attached to the second adhesive layer. In one embodiment, the peel force of the first release liner is greater than the peel force of the second release liner. The steps of the production method will be described in order.

A. Formation of a workpiece

A-1. Summary

First, a workpiece is formed. In the embodiment of the present invention, as shown in fig. 1, the optical layered bodies 100, … with the adhesive layers and the intermediate films 120, … are alternately stacked to form the work W. By forming the work by alternately stacking the optical laminate with the adhesive layer and the intermediate film, the lift-up of the release liner can be significantly suppressed. Particularly, the lift-up of the second release liner with a small release force (weak adhesive force) can be favorably suppressed. The optical laminate 100 with the adhesive layer may be stacked such that the first release liner 30 is on the upper side, or such that the second release liner 50 is on the upper side. The optical stack 100, preferably with an adhesive layer, is overlapped so that the first release liner 30 is on the upper side. With such a structure, the second release liner can be more favorably prevented from being lifted. The total thickness of the workpiece is, for example, 5mm to 50mm. The optical laminate with the adhesive layer and the intermediate film are stacked so that the work becomes such a total thickness. The number of sheets of the adhesive layer-attached optical laminate included in the work varies depending on the thickness of the adhesive layer-attached optical laminate. The number of sheets of the optical laminate with the adhesive layer is, for example, 5 to 100 sheets. The intermediate film 120 typically overlaps the upper and lower outermost layers of the workpiece as shown in fig. 1. That is, in the work, the number of sheets of the intermediate film 120 is 1 sheet more than that of the optical laminate 100 with the adhesive layer. With such a structure, the formation of an indentation of the optical laminate with the adhesive layer by the clamp at the time of cutting can be suppressed. In the embodiment of the present invention, since the intermediate film is included in the work, the number of sheets of the optical laminate with the adhesive layer obtained from the work having the same thickness is smaller than that of the conventional manufacturing method, but on the other hand, the lift-up of the release liner can be significantly suppressed, and as a result, the defect of the adhesive layer can be significantly suppressed. That is, the technical idea of the general manufacturing method is to increase the yield, and the embodiment of the present invention is based on the technical idea opposite to the general manufacturing method.

A-2 optical laminate with adhesive layer

Fig. 2 is a schematic cross-sectional view illustrating an example of an optical laminate with an adhesive layer. The optical laminate 100 with an adhesive layer illustrated in the figure includes: an optical film 10; a first adhesive layer 20 disposed on one side of the optical film 10; a first release liner 30 releasably temporarily attached to the first adhesive layer 20; a second adhesive layer 40 disposed on the other side of the optical film 10; and a second release liner 50 releasably and temporarily attached to the second adhesive layer. In the case where the adhesive layer-attached optical laminate is applied to an image display device, typically, the second release liner 50 (substantially the second adhesive layer 40) is disposed on the image display panel side. In practical use, the first release liner 30 and the second release liner 50 are peeled off and removed from the optical laminate with the adhesive layer. Typically, the first adhesive layer 20 can be used to attach a front panel (e.g., cover glass); the second adhesive layer 40 can be used to attach the adhesive layer-attached optical laminate to an image display device (essentially an image display panel).

The optical film 10 may be any suitable optical film that can be used for the application requiring cutting. The optical film may be a film formed of a single layer or may be a laminate. Specific examples of the optical film having a single layer include a polarizing plate and a retardation film. Specific examples of the optical film configured in the form of a laminate include a polarizing plate (typically, a laminate of a polarizing plate and a protective film), a conductive film for a touch panel, a surface-treated film, and a laminate in which an optical film configured of these single layers and/or an optical film configured in the form of a laminate are appropriately laminated according to the purpose (for example, an antireflection circular polarizing plate, a polarizing plate with a conductive layer for a touch panel). In the illustrated example, the optical film 10 includes a polarizing plate 11 and a retardation layer 12 in this order from the first adhesive layer 20 side. Therefore, the optical film 10 illustrated in the drawing may be an antireflection circular polarizing plate.

The storage elastic modulus G' of the first adhesive layer 20 at 25 ℃ is preferably 1.0×10 ⁵(Pa)～2.5×10⁵ (Pa), more preferably 1.1×10 ⁵(Pa)～2.3×10⁵ (Pa), and further preferably 1.2×10 ⁵(Pa)～2.0×10⁵ (Pa). The storage elastic modulus can be obtained by, for example, dynamic viscoelasticity measurement. The first adhesive layer 20 may have any suitable structure as long as it has adhesiveness and transparency that can be used for optical applications and has the above-described desired storage elastic modulus. Specific examples of the adhesive constituting the first adhesive layer include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, polyurethane adhesives, epoxy adhesives, and polyether adhesives. The adhesive having the above-mentioned desired storage elastic modulus can be prepared by adjusting the kind, amount, combination and blending ratio of the monomers of the base resin forming the adhesive, the blending amount of the crosslinking agent, the reaction temperature, the reaction time, and the like. The base resin of the binder may be used alone or in combination of 2 or more. Acrylic adhesives are preferred from the viewpoints of transparency, processability, durability, and the like. The 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, the description of which is incorporated herein by reference.

The thickness of the first pressure-sensitive adhesive layer 20 is 50 μm or more, preferably 70 μm to 1000 μm, more preferably 100 μm to 700 μm, and even more preferably 200 μm to 600 μm as described above.

The second adhesive layer 40 can have a structure known in the art and used conventionally. The thickness of the second adhesive layer 40 may be, for example, 10 μm to 50 μm, and may be, for example, 10 μm to 30 μm.

The first and second release liners 30 and 50 can each be any suitable release liner. Specific examples thereof include plastic films, nonwoven fabrics, and papers, which are surface-coated with a release agent. Specific examples of the release agent include silicone release agents, fluorine release agents, and long-chain alkyl acrylate release agents. Specific examples of the plastic film include polyethylene terephthalate (PET) film, polyethylene film, and polypropylene film. The thickness of the release liner may be, for example, 10 μm to 100 μm.

In one embodiment, the peel force of the first release liner 30 is greater than the peel force of the second release liner 50. With such a structure, the effect of the embodiment of the present invention (i.e., suppression of the lift-up of the release liner) is remarkable. The peel force of the first release liner 30 is preferably 0.05N/10mm to 0.5N/10mm; the peel force of the second release liner 50 is preferably 0.01N/10mm to 0.02N/10mm; the difference in peel force ("first release liner" - "second release liner") is preferably 0.03N/10mm to 0.45N/10mm.

A-3 intermediate film

The thickness of the intermediate film 120 is preferably 75 μm to 1000 μm, more preferably 150 μm to 750 μm, still more preferably 200 μm to 600 μm, particularly preferably 300 μm to 500 μm. If the intermediate film is too thin, the effect of suppressing warpage may be insufficient, and it may be difficult to alternately laminate the intermediate film and the optical laminate with the adhesive layer. If the intermediate film is too thick, productivity may be insufficient.

The intermediate film 120 may be any suitable resin film as long as the effects of the embodiments of the present invention can be obtained. The intermediate film is typically made of a polyester resin, preferably polyethylene terephthalate. In the case of such a structure, the intermediate film is prevented from being melted during cutting, so that contamination of the optical laminate with the adhesive layer due to the melted resin can be prevented. The intermediate film may be formed of a (meth) acrylic resin, a polyimide resin, a polyamide resin (for example, nylon), or the like.

The modulus of elasticity of the intermediate film may be, for example, 2.2kN/mm ²～4.8kN/mm². The elastic modulus was measured in accordance with JIS K6781.

B. Cutting of the outer peripheral surface of a workpiece

B-1. Summary

Next, the outer peripheral surface of the workpiece W is cut. Fig. 3 is a schematic perspective view illustrating the outline of cutting (hereinafter, sometimes referred to as "cutting process") of the outer peripheral surface. As described in item a-1 above with reference to fig. 1, the work W is formed as shown in fig. 3 by alternately stacking a plurality of adhesive-layer-attached optical laminates and a plurality of intermediate films. In the example shown in the figure, the work W has outer peripheral surfaces 1a, 1b facing each other and outer peripheral surfaces 1c, 1d orthogonal thereto. The workpiece W is preferably clamped from above and below by a clamping mechanism (not shown). The clamping mechanism (e.g., clamp) may be composed of a soft material or a hard material. In the case of being composed of a soft material, the hardness (JIS A) thereof is preferably 60 DEG to 80 deg. If the hardness is too high, there may be an indentation due to the residual clamp mechanism. If the hardness is too low, the jig may be deformed to shift its position, resulting in insufficient cutting accuracy. The optical laminate with the adhesive layer is cut into any suitable shape when forming a workpiece. Specifically, the optical laminate with the adhesive layer may be cut into a rectangular shape as in the example shown in the figure, may be cut into a shape similar to a rectangular shape (for example, a rectangular shape formed into a concave shape when viewed from the center of the long side), or may be cut into an appropriate shape (for example, a circular shape) that meets the purpose.

B-2 end mill

The cutting process can be performed by any suitable means. Specifically, the cutting process may be a so-called milling process or an end mill process as shown in fig. 3. An end mill machining is described below as a representative example of the cutting machining. First, an end mill that can be used for cutting is described.

The end mill may suitably use an end mill having a helical edge. Fig. 4 is a schematic perspective view for explaining the structure of an end mill having a helical blade. As shown in fig. 4, the end mill 60 having a helical blade includes: a rotation shaft 61 extending in the lamination direction (vertical direction) of the work W; and a cutting edge 62 configured to be the outermost diameter of the main body rotating around the rotation shaft 61. In the illustrated example, the cutting edge 62 is configured to have an outermost diameter twisted along the rotation shaft 61, and shows a right-hand edge right-hand spiral. The cutting edge 62 includes a cutting edge 62a, a rake surface 62b, and a flank surface 62c. The number of cutting edges 62 may be appropriately set according to the purpose. In the example shown in the figure, the number of cutting edges is 3, but the number of cutting edges may be 1, 2, 4, or 5 or more. The edge angle of the end mill (the helix angle θ of the cutting edge in the example of the figure) is preferably 20 ° to 70 °, more preferably 30 ° to 60 °. The relief surface of the cutting edge is preferably roughened. The roughening treatment may be any suitable treatment. Typical examples include sand blasting. By applying the roughening treatment to the flank surface, the adhesion of the adhesive to the cutting edge can be suppressed, and as a result, the blocking can be suppressed. The outer diameter of the end mill is preferably 5mm to 20mm, more preferably 10mm to 20mm. In the present specification, "blocking" refers to a phenomenon in which optical laminates with adhesive layers of a work are bonded to each other by an adhesive on end surfaces, and chipping of the adhesive attached to the end surfaces promotes adhesion of the optical laminates with adhesive layers to each other. The "outer diameter of the end mill" is a value obtained by multiplying the distance from the rotation axis 61 to the cutting edge 62a by 2 times. The end mill may be a single-sided fixed end mill with one end (upper end) fixed, or a double-sided fixed end mill with both ends (upper end and lower end) fixed.

The chip flute area of each blade of the end mill having the helical blade is preferably 5mm ² or more, more preferably 10mm ² or more, and still more preferably 11mm ²～40mm². The chip flute ratio of each blade of the end mill having the helical blade is preferably 35% to 55%, more preferably 38% to 52%, and even more preferably 42% to 50%. When the chip pocket area and the chip pocket ratio of each blade are within such a range, the lift-up of the release liner can be favorably suppressed. As shown in fig. 5, the chip flute area means: when the end mill is seen from the rotation axis direction, the difference between the area of an imaginary circle (a circle formed by the broken line in fig. 5) having the outer diameter of the end mill as the diameter and the projected area of the end mill body (the solid line portion in fig. 5) is obtained. The flute area of each blade can be found by dividing the flute area by the number of blades. The chip flute ratio can be obtained by dividing the chip flute area by the area of the imaginary circle. The chip flute area may be obtained by any suitable image processing. In addition, the chip flute area is affected by the outer diameter and the number of edges of the end mill, but in the embodiment of the present invention, the lift-up of the release liner can be favorably suppressed by optimizing the chip flute area regardless of the outer diameter and the number of edges.

Helical files may also be used as end mills. Fig. 6 is a schematic perspective view for explaining the structure of the helical file. The helical file 70 is typically constructed by attaching diamond particles to an end mill having helical blades, as shown in fig. 6. Specifically, the helical file 70 has: a rotation shaft 71 extending in the lamination direction (vertical direction) of the work W; and a cutting edge 72 configured to be the outermost diameter of the main body rotating around the rotation shaft 71. Diamond particles are attached to the cutting edge 72 to form a file portion 73. In the illustrated example, the cutting edge 72 is configured to have an outermost diameter twisted along the rotation shaft 71, and shows a right-hand edge right-hand spiral. The cutting edge 72 includes a cutting edge 72a, a rake surface 72b, and a flank surface 72c. The number of cutting edges 72 can be appropriately set according to the purpose. In the example shown in the figure, the number of cutting edges is 3, but the number of cutting edges may be 1,2, 4, or 5 or more. The helix angle θ is preferably 10 ° to 70 °, more preferably 30 ° to 60 °. The rake angle is preferably 1 ° to 25 °, more preferably 3 ° to 20 °, and still more preferably 3 ° to 10 °. In one embodiment, as shown in FIG. 7, the helical file 70 (essentially the cutting edge 72) has no relief. That is, the edge 72a has a flat surface, and the edge 72a can be brought into surface contact with the surface to be machined (cut) of the workpiece. With such a structure, an optical laminate with an adhesive layer that can suppress the occurrence of cracks even in a severe environment such as a thermal shock test can be obtained. The width B of the flat surface of the blade edge 72a is preferably 0.1mm or more, more preferably 0.2mm to 1.4mm, and even more preferably 0.4mm to 1.0mm. If the width is too small, the effect of suppressing the cracks may be insufficient. If the width is too large, the file may be substantially equivalent to a rod file, and the effect as a helical file may not be obtained. In addition, fig. 7 is a schematic view for convenient viewing, and does not correspond to the helical file of fig. 6.

The machining by the helical file may be performed by "normal machining" in which the rake face 72b side is the upstream side in the rotation direction, or by "back machining" in which the flank face 72c side (the back side of the blade) is the upstream side in the rotation direction. In the case of "back machining", even when the relief angle is provided (when the width B of the flat surface of the edge 72a is 0, for example, the relief angle may be 2 to 25 °), the edge 72a and the machined (cut) surface of the workpiece are in a state of being in surface contact with each other, so that a sufficient crack suppression effect can be obtained even when the relief angle is provided. The "back machining" can be achieved by, for example, the following means: reversing the rotation direction of the helical file; or the rotation direction of the helical file is made the same as in the case of the general machining and the installation is made opposite to that in the case of the general machining.

Fig. 8 is a schematic cross-sectional view of a main portion for explaining the uneven shape of the file body 73. The depth D of the irregularities of the file portion 73 is, for example, 5 μm to 120. Mu.m. The lower limit of the depth D is preferably 8 μm or more, more preferably 15 μm or more. The upper limit of the depth D is preferably 50 μm or less, more preferably 35 μm or less. The pitch P of the irregularities of the file portion 73 is, for example, 5 μm to 250 μm. The lower limit of the pitch P is preferably 10 μm or more, more preferably 25 μm or more. The upper limit of the pitch P is preferably 100 μm or less, more preferably 60 μm or less. The diameter (outer diameter) of the helical file 70 (substantially the cutting edge 72) may be, for example, 2mm to 12mm. The length L of the file portion 73 may be, for example, 10mm to 100mm. In the present specification, the "diameter of the helical file" is a value obtained by multiplying the distance from the rotation shaft 71 to the cutting edge 72a by 2 times, as in the case of the "diameter of the end mill" described above. The arithmetic average height (Sa) of the surface of the file portion 73 is preferably 1 μm to 15 μm, more preferably 3 μm to 10 μm. The maximum height (Sz) of the surface of the file portion 73 is preferably 10 μm to 100 μm, more preferably 25 μm to 80 μm. These surface roughnesses can be determined according to the "non-contact (optical probe)" evaluation method of ISO 25178. Specifically, the measurement can be performed by a laser microscope (manufactured by Keyence Co., ltd., product name "VK-X1000"). The diamond particles have a particle diameter of, for example, 1 μm to 100. Mu.m.

The granularity of the shank of the helical file may be, for example, #100 or more, preferably #200 or more, more preferably #500 or more. The granularity of the file portion may be, for example, #3000 or less, preferably #2500 or less, and more preferably #2200 or less. The particle size may be adjusted by the size of the diamond particles, etc.

B-3 specific step of cutting

Cutting is typically performed by rotating an end mill while bringing a cutting edge of the end mill into contact with an outer peripheral surface of a workpiece, and relatively moving the end mill and the workpiece. The cutting is performed by rotation and relative movement of the end mill. In the cutting process, only the end mill may be moved, only the workpiece may be moved, or both the end mill and the workpiece may be moved.

The cutting process may be performed only 1 time, or may be performed a plurality of times (for example, 2 times, 3 times, or 4 times or more). In one embodiment, the cutting process is performed only 1 time. In this case, the cutting process is typically performed using an end mill having a helical blade. In another embodiment, the cutting process is performed 2 times. At this time, the cutting process preferably includes: rough cutting with an end mill having a helical blade, and finish cutting with a helical file. By performing finish cutting with a helical file, a lack of adhesive (a state in which the end of the adhesive layer is missing) can be formed. As a result, so-called glue blocks can be significantly suppressed. The amount of the adhesive deficiency formed by the finish cutting of the helical file may be, for example, 10 μm to 500 μm. In the present specification, the term "glue block" means: the adhesive used to form the adhesive layer overflows from the end face during cutting, and the overflowed adhesive is granulated. The amount of cutting obtained with fine cutting is typically significantly lower than that obtained with rough cutting. With such a structure, the dimensional accuracy of the optical laminate with the adhesive layer can be maintained, and excellent quality (for example, suppression of warpage and interlayer peeling) can be maintained. For example, the cutting amount obtained by rough cutting is preferably about 0.1mm to 0.5 mm; the amount of cutting by finish cutting is preferably about 0.01mm to 0.05 mm.

The conditions for cutting can be appropriately set according to the purpose and the state of cutting. For example, as described above, the cutting process includes: in the case of rough cutting by an end mill having a helical blade and finish cutting by a helical file, the following cutting conditions can be adopted. The number of rotations of the end mill having the helical blade in rough cutting varies according to the outer diameter of the end mill. For example, when the outer diameter is 15mm, the rotation number is preferably 5000rpm to 15000rpm, more preferably 8000rpm to 10000rpm; for example, when the outer diameter is 6mm, the rotation number is preferably 1000rpm to 40000rpm, more preferably 15000rpm to 25000rpm. The peripheral speed (not affected by the outer diameter) of the end mill having the helical blade in rough cutting is preferably 200000 mm/min to 750000 mm/min, more preferably 250000 mm/min to 500000 mm/min. The feed speed of the end mill having the helical blade in rough cutting is preferably 500 mm/min to 2500 mm/min, more preferably 1000 mm/min to 2000 mm/min. The number of times of cutting the cutting portion in 1 rough cut may be 1, 2, 3 or more times. The number of revolutions of the helical file in finish cutting varies according to the outer diameter of the helical file. For example, when the outer diameter is 15mm, the rotation number is preferably 2000rpm to 6000rpm, more preferably 3000rpm to 4000rpm; for example, when the outer diameter is 6mm, the rotation number is preferably 5000rpm to 15000rpm, more preferably 7000rpm to 10000rpm. The peripheral speed of the helical file in finish cutting (independent of the outer diameter) is preferably 95000 mm/min to 300000 mm/min, more preferably 150000 mm/min to 200000 mm/min. The feed speed of the helical file in finish cutting is preferably 300 mm/min to 2000 mm/min, more preferably 500 mm/min to 1000 mm/min. The number of cutting times of the cutting part in the 1-time finish cutting can be 1 time, 2 times, 3 times or more.

Examples

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The measurement method of each characteristic of the examples is as follows.

(1) Thickness of (L)

The thickness of 10 μm or less was measured by using an interferometer (product name "MCPD-3000" manufactured by Katsukamu electronics Co., ltd.). Thicknesses greater than 10 μm were measured using a digital micrometer (product name "KC-351C" manufactured by Anritsu Co.).

(2) Lift-off of release liner

The optical laminate with the adhesive layer after the cutting processing is selected from the work, and the entire periphery of each optical laminate with the adhesive layer is observed using a magnifying glass or a microscope. The maximum amount of lift-off of the first and second release liners of the optical laminate with the predetermined number of adhesive layers was taken as "lift-off of the release liner", and evaluated as follows.

A (good): less than 100 μm

B: 100 μm or more and less than 500 μm

C: 500 μm or more and less than 900 μm

D (bad): 900 μm or more

Example 1

1. Production of optical laminate with adhesive layer

The polarizing plate was obtained by uniaxially stretching a long polyvinyl alcohol (PVA) -based resin film containing iodine in the longitudinal direction (MD direction) (thickness 12 μm). A long optical functional film (HC-TAC film) is bonded to one side of the polarizing plate so that the longitudinal directions of both are aligned. The HC-TAC film was a film in which a Hard Coat (HC) layer (2 μm) was formed on a triacetyl cellulose (TAC) film (25 μm), and the TAC film was laminated on the polarizing plate side to obtain a laminate of HC layer/protective layer (TAC film)/polarizing plate. In addition, a general acrylic adhesive (thickness: 5 μm) was used for lamination. Next, a polycarbonate resin film (refractive index characteristics: nx > ny=nz, in-plane retardation: about 140 nm) was laminated as a retardation layer on the surface of the polarizing plate of the obtained laminate. The lamination was performed such that the absorption axis of the polarizing plate and the slow axis of the retardation layer form an angle of 45 °. In addition, the lamination was carried out using a general acrylic pressure-sensitive adhesive (thickness: 5 μm) in the same manner as described above. A laminate of an HC layer/protective layer (TAC film)/polarizing plate/retardation layer was obtained according to the above manner. A first adhesive layer (storage elastic modulus: 1.2X10 ⁵ Pa, thickness: 500 μm) was formed on the HC layer surface of the obtained laminate, and a first release liner was temporarily adhered to the first adhesive layer. A second pressure-sensitive adhesive layer (storage elastic modulus: 1.25X10 ¹¹ Pa, thickness: 20 μm) was formed on the surface of the retardation layer of the laminate, and a second release liner was temporarily adhered to the second pressure-sensitive adhesive layer. An optical laminate with an adhesive layer was produced in the above manner.

2. Cutting process

The adhesive layer-attached optical laminate obtained in the above manner was punched into a rectangle of 330mm×140 mm. In this case, the polarizing plate is punched so that the absorption axis direction of the polarizing plate is the short side direction. On the other hand, a PET film having a thickness of 350 μm and having the same size as the punched optical laminate with the adhesive layer was prepared and used as an intermediate film. The punched optical laminate with the adhesive layer and the intermediate film are alternately stacked to form a work (thickness 5mm or more). Here, the optical laminate with the adhesive layer is overlapped with the intermediate film so that the upper and lower outermost layers of the work are intermediate films (that is, so that the intermediate film is 1 sheet more than the optical laminate with the adhesive layer). The entire outer peripheral end face of the obtained workpiece is cut by an end mill. The pitch angle of the end mill is 50 °, the rake angle is 5 °, and the relief angle is 15 °. The end mill had an outer diameter of 8mm, the number of blades of 4, an area of an imaginary circle having an outer diameter as a diameter (hereinafter, referred to as "cross-sectional area" for convenience) of 50.2mm ², a cross-sectional area of each blade of 12.6mm ², a chip pocket area of each blade of 6.4mm ², and a chip pocket ratio of each blade of 50.7%. As a cutting condition, the rotation number of the end mill was 15000rpm (circumferential speed: 38000 mm/min), and the feed speed was 1500 mm/min. The optical laminate with the adhesive layer after the cutting was subjected to the evaluation of (2) above. The results are shown in Table 1.

3. Glue block

After visually observing a workpiece (an optical laminate having a substantially adhesive layer) cut with an end mill, the presence of a glue block was confirmed. The workpiece is further subjected to cutting processing by a helical file. The diameter of the spiral file is 6mm, the number of blades is 4, the helix angle is 45 degrees, the front angle is 5 degrees, no back angle exists, the width of the flat surface of the cutter point is 0.6mm, and the granularity of the file body part is #1000. As a cutting condition, the rotation number of the helical file was 8000rpm (circumferential speed: 150000 mm/min), and the feed speed was 900 mm/min. After visually observing the work piece (the optical laminate with the adhesive layer substantially) cut with the helical file, the glue cake was removed to an unrecognizable extent.

Examples 2 to 8

A workpiece (substantially an optical laminate with an adhesive layer) was cut with an end mill in the same manner as in example 1 except that the outer diameter and the number of edges (as a result, the cross-sectional area, the chip flute area, and the chip flute ratio) of the end mill were changed as shown in table 1. The results are shown in Table 1.

For each of examples 2 to 8, after visually observing the work piece (the optical laminate having a substantially adhesive layer) cut with the end mill, the existence of the glue block was confirmed. Each workpiece is further subjected to cutting processing by a helical file. As a result, the glue cake can be removed to such an extent that it cannot be visually recognized.

Comparative example 1

A work was formed in the same manner as in example 1 except that the intermediate film was not used, that is, only the optical laminate with the adhesive layer was overlapped. The workpiece was cut with an end mill in the same manner as in example 2. The results are shown in Table 1. In addition, as shown in table 1, since the tilting of the present comparative example is poor, the cutting process (evaluation of the rubber mass) by the helical file was not performed.

TABLE 1

As is apparent from table 1, according to the examples of the present invention, the lift-up of the release liner can be suppressed by cutting a work piece formed by alternately overlapping the optical laminate with the adhesive layer and the interlayer film with an end mill. Further, by setting the chip flute area of the end mill to a predetermined value or more, the lift-up of the release liner can be significantly suppressed.

Industrial applicability

The adhesive layer-attached optical laminate obtained by the manufacturing method according to the embodiment of the present invention can be suitably used for an image display device.

Description of the reference numerals

W: a workpiece; 10: an optical film; 11: a polarizing plate; 12: a phase difference layer; 20: a first adhesive layer; 30: a first release liner; 40: a second adhesive layer; 50: a second release liner; 60: an end mill; 70: a helical file; 100: an optical laminate with an adhesive layer; 120: an intermediate film.

Claims

1. A method for producing an optical laminate with an adhesive layer, comprising:

Alternately overlapping the optical laminated body with the adhesive layers and the intermediate films to form a workpiece; and cutting the outer peripheral surface of the workpiece.

2. The manufacturing method according to claim 1, wherein,

The thickness of the intermediate film is 75-1000 mu m.

3. The manufacturing method according to claim 1 or 2, wherein,

The intermediate film is made of a polyester resin.

4. The manufacturing method according to any one of claims 1 to 3, wherein the adhesive layer-attached optical laminate comprises:

An optical film;

a first adhesive layer which is arranged on one side of the optical film and has a thickness of 50 [ mu ] m or more;

A first release liner releasably temporarily attached to the first adhesive layer;

A second adhesive layer disposed on the other side of the optical film;

a second release liner releasably temporarily attached to the second adhesive layer;

The first release liner has a release force greater than the release force of the second release liner.

5. The manufacturing method according to claim 4, wherein,

The optical film includes a polarizing plate and a retardation layer in this order from the first adhesive layer side.

6. The manufacturing method according to any one of claims 1 to 5, wherein,

Cutting the workpiece comprises: cutting by an end mill.

7. The manufacturing method according to claim 6, wherein,

The end mill has helical edges, and the chip flute area of each edge is more than 5mm ².

8. The manufacturing method according to claim 6 or 7, wherein,

The outer diameter of the end mill is 10 mm-20 mm.

9. The manufacturing method according to any one of claims 6 to 8, wherein,

The cutting with the end mill includes: cutting with a helical file.

10. The manufacturing method according to claim 9, wherein,

The cutting with the end mill includes: rough cutting with an end mill having a helical blade, and finish cutting with a helical file.