JP7257809B2 - Method for producing cut optical laminate with pressure-sensitive adhesive layer - Google Patents

Description

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

Various optical laminates (e.g., polarizing plates) are used in image display devices such as mobile phones and notebook personal computers to realize image display and/or improve the performance of the image display. . Typically, the optical layered body is provided with a pressure-sensitive adhesive layer as the outermost layer so that the optical layered body can be attached to the image display cell. Practically, a separator is temporarily attached to the pressure-sensitive adhesive layer in a releasable manner to protect the pressure-sensitive adhesive layer until it is actually used. Further, on the side of the optical layered body opposite to the pressure-sensitive adhesive layer, a surface protection film is temporarily adhered in a detachable manner. In recent years, it has been desired to process the shape of the optical layered body into a desired shape. Such a processing method includes, for example, end face cutting using an end mill.

Japanese Unexamined Patent Application Publication No. 2018-22140

Here, when the optical layered body is attached to another optical member, the ease of peeling of the surface protective film (hereinafter sometimes simply referred to as peelability) is required. Moreover, in end face cutting using an end mill, the cut surface may become tapered when viewed from the lateral direction. The present invention was made to solve such problems, and its main purpose is to suppress the peeling failure of the surface protective film and to suppress the taper of the cut surface. An object of the present invention is to provide a method for easily and inexpensively producing a pressure-sensitive adhesive layer-attached optical layered body.

In the method for manufacturing a machined pressure-sensitive adhesive layer-attached optical layered body of the present invention, a plurality of pressure-sensitive adhesive layer-attached optical layered bodies are laminated to form a work; and further cutting the outer peripheral surface of the cut work using an end mill with a blade angle of 0°. The pressure-sensitive adhesive layer-attached optical laminate comprises an optical film, a pressure-sensitive adhesive layer disposed on one side of the optical film, a separator temporarily attached to the pressure-sensitive adhesive layer in a peelable manner, and another layer of the optical film. and a surface protection film releasably temporarily adhered to one side. In the manufacturing method of the present invention, the work is formed by stacking the pressure-sensitive adhesive layer-attached optical layered body so that the separator is positioned in the discharge direction of the shavings of the end mill having the helical blade.
In one embodiment, the end mill having the twisted blade has a right-handed right-handed blade or a left-handed left-handed blade, and the pressure-sensitive adhesive layer-attached optical layered body is superimposed so that the separator is positioned on the upper side, and a workpiece is formed. is formed. In another embodiment, the end mill having a twisted blade is a right-handed left-handed blade or a left-handed right-handed blade, and the pressure-sensitive adhesive layer-attached optical layered body is superimposed such that the separator is positioned on the lower side, A workpiece is formed.
In one embodiment, the amount of cutting by the end mill having the helical edge is 0.1 mm to 0.5 mm, and the amount of cutting by the end mill with the blade angle of 0° is 0.01 mm to 0.2 mm.
In one embodiment, the manufacturing method causes the surface protective film to float by cutting with the end mill having the helical blade. In one embodiment, the floating amount of the surface protective film is 1 μm to 1000 μm.
In one embodiment, the manufacturing method includes cutting the outer peripheral surface of the workpiece non-linearly. In one embodiment, the nonlinear cutting includes forming a concave portion including a curved portion when the pressure-sensitive adhesive layer-attached optical layered body is viewed from above. In one embodiment, the curved portion has a radius of 5 mm or less.
In one embodiment, the optical film is a polarizer or polarizing plate.

According to the present invention, in a method for producing an optical laminate with an adhesive layer, the method includes forming a work by stacking a plurality of optical laminates with an adhesive layer, and cutting the outer peripheral surface of the work with an end mill, After cutting the outer peripheral surface using an end mill having a helical blade, the cut surface is further cut using an end mill with a blade angle of 0°, and the separator is positioned in the discharge direction of the shavings of the end mill having a helical blade. By cutting the workpiece formed by stacking the pressure-sensitive adhesive layer-attached optical laminate in this way, the peeling failure of the surface protective film is suppressed, and the cut surface is suppressed from becoming tapered. It is possible to realize a method for easily and inexpensively producing an optical layered body with a pressure-sensitive adhesive layer.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing explaining an example of the optical laminated body with an adhesive layer which can be used for the manufacturing method of this invention. 1 is a schematic diagram illustrating a representative example of the configuration of an end mill having a helical blade that can be used in the manufacturing method of the present invention; FIG. FIG. 4 is a schematic plan view for explaining the difference in cutting direction between a right-handed end mill and a left-handed end mill having a helical edge that can be used in the manufacturing method of the present invention. (a) is a schematic front view of a main part explaining a method of forming a workpiece in one embodiment of the present invention; (b) is a schematic front view of a main part explaining a method of forming a workpiece in another embodiment; is. It is a schematic perspective view for demonstrating cutting in the manufacturing method of this invention. FIG. 2 is a schematic diagram for explaining the structure of an end mill having a helical edge used for cutting in the manufacturing method of the present invention; It is a schematic diagram for explaining the structure of an end mill with a blade angle of 0° used for cutting in the manufacturing method of the present invention. FIG. 2 is a schematic plan view showing an example of the shape of a cut pressure-sensitive adhesive layer-carrying optical layered body obtained by the production method of the present invention. (a) to (c) are schematic plan views for explaining a series of steps of cutting in the manufacturing method of the present invention.

Specific embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. The drawings are shown schematically for the sake of clarity, and the ratios of length, width, thickness, etc., and angles, etc. in the drawings are different from the actual ones.

The method for producing the pressure-sensitive adhesive layer-attached optical layered body of the present invention includes stacking a plurality of pressure-sensitive adhesive layer-attached optical layered bodies to form a work; and cutting the outer peripheral surface of the work using an end mill having a twisted blade. and further cutting the cut outer peripheral surface of the work using an end mill with a blade angle of 0°. The pressure-sensitive adhesive layer-attached optical laminate comprises an optical film, a pressure-sensitive adhesive layer disposed on one side of the optical film, a separator releasably temporarily attached to the pressure-sensitive adhesive layer, and a separator on the other side of the optical film. and a surface protection film that is releasably attached temporarily. In an embodiment of the present invention, the work is formed by stacking the pressure-sensitive adhesive layer-carrying optical layered body so that the separator is positioned in the discharge direction of the shavings of an end mill having a helical blade. For convenience, first, a specific configuration of the pressure-sensitive adhesive layer-attached optical layered body that can be used in the method for producing the pressure-sensitive adhesive layer-attached optical layered body of the present invention will be described, and then the pressure-sensitive adhesive layer-attached optical layered body of the present invention will be described. A manufacturing method will be described.

A. 1. Optical Layered Body with Adhesive Layer FIG. 1 is a schematic cross-sectional view illustrating an example of an optical layered body with an adhesive layer that can be used in the production method of the present invention. The adhesive layer-attached optical laminate 100 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 in a detachable manner. , and a surface protection film 40 releasably temporarily attached to the other side of the optical film 10 . When the pressure-sensitive adhesive layer-attached optical layered body is applied to an image display device, the separator 30 is typically arranged on the image display cell side. When the pressure-sensitive adhesive layer-attached optical laminate is actually used, the separator 30 is removed by peeling, and the pressure-sensitive adhesive layer 20 is used to bond the pressure-sensitive adhesive layer-attached optical laminate to an image display device (substantially, an image display cell). can be used for The surface protective film 40 typically has a substrate 41 and an adhesive layer 42 . In order to distinguish from the adhesive layer 20, the adhesive layer 42 of the surface protection film may be referred to as "PF adhesive layer". The surface protective film 40 is also peeled off when the pressure-sensitive adhesive layer-attached optical laminate is actually used. In the embodiment of the present invention, by adopting the manufacturing method described later, it is possible to realize a machined pressure-sensitive adhesive layer-attached optical layered body in which peeling defects of the surface protective film are suppressed. That is, according to the embodiment of the present invention, it is possible to suppress peeling failure of the surface protective film, which is a problem peculiar to the pressure-sensitive adhesive layer-attached optical laminate including the pressure-sensitive adhesive layer, the separator, and the surface protective film.

The optical film 10 includes any suitable optical film that can be used for applications that require cutting (especially non-linear processing). The optical film may be a film composed of a single layer, or may be a laminate. Specific examples of optical films composed of a single layer include polarizers and retardation films. Specific examples of the optical film configured as a laminate include a polarizing plate (typically, a laminate of a polarizer and a protective film), a conductive film for a touch panel, a surface treatment film, and a single layer thereof. Optical films and/or laminates (for example, antireflection circularly polarizing plates, polarizing plates with conductive layers for touch panels) in which optical films are appropriately laminated according to the purpose are exemplified.

Any appropriate configuration can be adopted as the pressure-sensitive adhesive layer 20 . Specific examples of adhesives constituting the adhesive layer include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. is mentioned. By adjusting the type, number, combination and compounding ratio of the monomers forming the base resin of the adhesive, as well as the compounding amount of the cross-linking agent, the reaction temperature, the reaction time, etc., an adhesive having desired properties according to the purpose. can be prepared. The base resin of the adhesive may be used alone or in combination of two or more. Acrylic pressure-sensitive adhesives are preferred from the viewpoint of transparency, workability, durability, and the like. Details of the adhesive constituting the adhesive layer are described, for example, in JP-A-2014-115468, and the description of the publication is incorporated herein by reference. The thickness of the adhesive layer 20 can be, for example, 10 μm to 100 μm. The storage modulus G' of the pressure-sensitive adhesive layer 20 at 25°C can be, for example, 1.0 x ¹⁰⁴ (Pa) to 1.0 x ¹⁰⁶ (Pa). Note that the storage modulus can be obtained, for example, from dynamic viscoelasticity measurement.

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

The surface protection film 40 typically has the substrate 41 and the adhesive layer 42 as described above. Materials for forming the substrate 41 include, for example, ester-based resins such as polyethylene terephthalate-based resins, cycloolefin-based resins such as norbornene-based resins, olefin-based resins such as polypropylene, polyamide-based resins, polycarbonate-based resins, and copolymers thereof. Coalescing resins may be mentioned. Ester-based resins (especially polyethylene terephthalate-based resins) are preferred. Such a material has a sufficiently high elastic modulus, and has the advantage of being resistant to deformation even when tension is applied during transportation and/or lamination.

The modulus of elasticity of the substrate 41 can be, for example, 2.2 kN/mm ² to 4.8 kN/mm ² . If 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 lamination. The elastic modulus is measured according to JIS K6781.

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

Any appropriate configuration can be adopted as the adhesive layer (PF 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 compounding ratio of the monomers forming the base resin of the adhesive, as well as the compounding amount of the cross-linking agent, the reaction temperature, the reaction time, etc., an adhesive having desired properties according to the purpose. can be prepared. The base resin of the 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 adhesive constituting the PF adhesive layer are described, for example, in JP-A-2018-123281, and the description of the publication is incorporated herein by reference. The thickness of the PF adhesive layer 42 can be, for example, 10 μm to 100 μm. The storage modulus G′ of the PF adhesive layer 42 at 25° C. can be, for example, 0.5×10 ⁶ (Pa) to 3.0×10 ⁶ (Pa). If the storage elastic modulus is within such a range, it is possible to obtain a pressure-sensitive adhesive layer (as a result, a surface protective film) with an excellent balance between pressure-sensitive adhesiveness and peelability. Furthermore, according to the production method described later, it is possible to cause the surface protective film to float, and as a result, it becomes easy to concentrate the stress on the peeling point by using the floated part as a gripping margin, so that the adhesiveness is acceptable. While maintaining the above, more excellent peelability can be achieved.

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

In one embodiment, the peeling force between the separator 30 and the adhesive layer 20 (hereinafter also referred to as the peeling force of the separator) is the optical film 10 and the surface protective film 40 (substantially, the PF adhesive layer 42) It is smaller than the peeling force (hereinafter also referred to as the peeling force of the surface protective film). In many cases, the peeling force of the surface protective film is greater than the peeling force of the separator, and poor peeling of the surface protective film is likely to occur. A processed optical laminate with an adhesive layer can be obtained. More specifically, the peel force of the separator is preferably 0.001 N/10 mm to 1.0 N/10 mm, and the peel force of the surface protection film is preferably 0.01 N/10 mm to 5.0 N/10 mm. The peeling force of the separator is more preferably 0.001 to 0.1 N/10mm, still more preferably 0.005 to 0.03N/10mm. The peeling force of the surface protective film is more preferably 0.01 to 0.5 N/10 mm, still more preferably 0.035 to 0.1 N/10 mm. The difference between the peel strength of the separator and the peel strength of the surface protective film (the peel strength of the surface protective film - the peel strength of the separator) is preferably 0.01 N/10 mm to 1.0 N/10 mm. According to the manufacturing method described later, even if there is such a difference in peel strength, it is possible to obtain a machined pressure-sensitive adhesive layer-carrying optical layered body in which peeling defects of the surface protective film are suppressed.

In one embodiment, the thickness of surface protection film 40 is greater than the thickness of separator 30 . According to the manufacturing method described below, excellent peelability can be achieved even when the thickness of the surface protective film is large and a large peeling force is required. The difference between the thickness of the surface protection film and the thickness of the separator (thickness of surface protection film - thickness of separator) is preferably 5 µm to 60 µm. According to the manufacturing method described later, even if there is such a difference in thickness, it is possible to obtain a cut optical layered body with an adhesive layer in which peeling defects of the surface protective film are suppressed.

B. Method for Producing Optical Layered Body with Adhesive Layer Hereinafter, a representative example of the method for producing an optical layered body with an adhesive layer will be described. First, the relationship between the configuration of the end mill having a helical blade, which is a characteristic part of the present invention, and the lamination state of the workpieces will be described, and then the outline of the manufacturing method will be described.

B-1. Relationship Between Configuration of End Mill and Lamination State of Work In an embodiment of the present invention, as described above, an optical layered body with an adhesive layer is formed such that the separator is positioned in the discharge direction of the cutting waste of the end mill having a twisted blade. A workpiece is formed by overlapping, and the outer peripheral surface of the workpiece is cut. A specific description will be given with reference to FIGS. 2 and 3. FIG. FIG. 2 is a schematic diagram illustrating a representative example of the configuration of an end mill having a helical edge that can be used in the manufacturing method of the present invention. FIG. 3 is a schematic plan view for explaining the difference in cutting direction between a right-handed end mill and a left-handed end mill having a helical blade. As shown in FIG. 2, the configurations of end mills having helical blades are broadly classified into right-hand twisted blades, left-hand twisted right blades, right-hand twisted left blades, and left-hand twisted left blades. As shown in FIG. 2, the right blade refers to a configuration that can cut when rotated clockwise when viewed from the upper side (shank side); A configuration that can be cut when rotated to As further shown in FIG. 2, a right twist refers to a configuration in which the cutting edge extends diagonally upward to the right when viewed from the side; a left twist refers to a configuration in which the cutting edge extends diagonally upward to the left when viewed from the side. In the case of the right-handed blade right twist and the left-handed blade left-handed twist, the cutting waste discharge direction is upward; As shown in FIG. 3, the cutting direction of the right blade is typically counterclockwise, and the cutting direction of the left blade is typically clockwise.

In the embodiment of the present invention, as described above, the pressure-sensitive adhesive layer-attached optical layered body is stacked to form a work so that the separator is positioned in the discharge direction of cutting waste of an end mill having a twisted blade, and the outer periphery of the work is formed. Cut the surface. For example, when the end mill having a twisted blade is a right-handed right-handed blade or a left-handed left-handed blade, as shown in FIG. A workpiece W is formed by stacking them. On the other hand, when the end mill is a right-handed left-handed blade or a left-handed right-handed blade, as shown in FIG. form W. The inventors of the present invention have found that the surface protective film may or may not lift depending on the relationship between the discharge direction of the cutting debris of the end mill having a twisted blade and the arrangement of the surface protective film of the pressure-sensitive adhesive layer-attached optical laminate on the workpiece. Furthermore, it was found that the problem of poor peeling of the surface protective film can be solved by causing the surface protective film to float. With the above configuration, the pressure-sensitive adhesive layer-attached optical layered body is scraped up (or scraped down) from the surface protection film side toward the separator side, and as a result, a strong cutting force is imparted in an oblique direction. It is possible to generate floating on the surface protection film. As a result, it is possible to obtain an optical layered body with a pressure-sensitive adhesive layer which is cut and in which defective peeling of the surface protective film is suppressed. The floating amount of the surface protection film is preferably 1 μm or more, more preferably 20 μm or more, and still more preferably 50 μm or more. On the other hand, the floating amount is preferably 1000 μm or less, more preferably 500 μm or less. If the floating amount is within such a range, it is possible to achieve good releasability of the surface protection film without causing other problems and maintaining the appearance quality within an allowable range. Floating lowers the quality of the appearance and is therefore avoided as much as possible in the industry. However, according to the embodiment of the present invention, the surface protective film is actively caused to float, which is completely different from the common technical knowledge in the industry. A technical concept in the opposite direction makes it possible to obtain an optical layered body with a pressure-sensitive adhesive layer which is cut and in which defective peeling is suppressed. In addition, if the relationship between the configuration of the end mill having a helical blade and the stacking state of the workpiece is reversed (that is, if the end mill having a helical blade is a right-handed or left-handed left-handed twisted blade, as shown in FIG. 4(b) When the work is formed as shown in Fig. 4 (a) when the end mill having a helical blade is a right-handed left-handed blade or a left-handed right-handed blade), the separator floats while the surface Floating does not occur on the protective film. As a result, it may not be possible to solve the problem of peeling failure of the surface protective film.

B-2. Formation of Work Next, an outline of cutting will be described. FIG. 5 is a schematic perspective view for explaining cutting in the manufacturing method of the present invention, in which a workpiece W is shown. As shown in FIG. 5, a workpiece W is formed by stacking a plurality of pressure-sensitive adhesive layer-attached optical laminates. As described in section B-1, the stacked state of the workpieces W is set as shown in FIG. 4(a) or 4(b) according to the configuration of the end mill having the helical blade. The pressure-sensitive adhesive layer-attached optical layered body is typically cut into any appropriate shape when forming a work. Specifically, the pressure-sensitive adhesive layer-attached optical layered body may be cut into a rectangular shape, may be cut into a shape similar to the rectangular shape, or may be cut into an appropriate shape (for example, a circle) according to the purpose. It may be disconnected. The workpiece W has outer peripheral surfaces (cutting surfaces) 1a and 1b facing each other and outer peripheral surfaces (cutting surfaces) 1c and 1d orthogonal thereto. The workpiece W is preferably clamped from above and below by clamping means (not shown). The total thickness of the work is preferably 8 mm to 20 mm, more preferably 9 mm to 15 mm, still more preferably about 10 mm. With such a thickness, it is possible to prevent damage due to pressure from the clamping means or impact during cutting. The pressure-sensitive adhesive layer-attached optical layered body is stacked so that the works have such a total thickness. The number of pressure-sensitive adhesive layer-attached optical layered bodies constituting the work may be, for example, 10 to 50 sheets. The clamping means (e.g., jig) may be composed 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, there may be impressions left by the clamping means. If the hardness is too low, the deformation of the jig may cause misalignment, resulting in insufficient cutting accuracy.

B-3. Cutting B-3-1. Cutting with an End Mill Having a Twisted Edge Next, the outer peripheral surface of the workpiece W is cut with an end mill 60 having a helical edge. Cutting is typically performed by bringing a cutting edge of an end mill into contact with the outer peripheral surface of the workpiece W. As shown in FIG. Cutting may be performed over the entire circumference of the outer peripheral surface of the work, or may be performed only at predetermined positions.

As shown in FIG. 6, an end mill 60 having a helical edge has a rotating shaft 61 extending in the stacking direction (vertical direction) of the workpiece W, and a cutting blade having an outermost diameter of a main body that rotates around the rotating shaft 61. 62 and . In the illustrated example, the cutting edge 62 is configured as an outermost diameter that is twisted along the axis of rotation 61, exhibiting a right edge right helix. The cutting blade 62 includes a cutting edge 62a, a rake face 62b, and a relief face 62c. The number of cutting blades 62 can be appropriately set according to the purpose. In the illustrated example, there are three cutting blades, but the number of blades may be one, two, four, or five or more. good. The blade angle of the end mill (helix angle θ of the cutting blade in the illustrated example) is preferably 20° to 60°, more preferably 30° to 45°. With such a blade angle, the surface protective film can be satisfactorily lifted by cutting. The relief surface of the cutting edge is preferably roughened. Any appropriate treatment can be adopted as the roughening treatment. A typical example is blasting. By roughening the relief surface, adhesion of the adhesive to the cutting blade is suppressed, and as a result, blocking can be suppressed. The outer diameter of the end mill is preferably 3 mm to 20 mm. In this specification, the term “blocking” refers to a phenomenon in which optical laminates with an adhesive layer adhere to each other with the adhesive on the end surfaces of a work, and the shavings of the adhesive adhered to the end surfaces are the optical laminate with an adhesive layer. It contributes to adhesion between bodies. Also, the "outer diameter of the end mill" refers to the distance from the rotating shaft 61 to the cutting edge 62a doubled. The end mill may be a cantilever end mill with one end (upper end) held, or a double end mill with both ends (upper end and lower end) held.

In embodiments of the present invention, cutting with an end mill having a helical edge can correspond to so-called rough cutting. First, it is cut with an end mill having a helical blade, and then, as described later, an end mill with a blade angle of 0° is used to further cut (finish) the cut surface, thereby suppressing poor peeling of the surface protective film. Moreover, it is possible to prevent the cutting surface from becoming tapered. The amount of cutting by an end mill having a helical edge is preferably about 0.1 mm to 0.5 mm.

B-3-2. Cutting with an End Mill with a Blade Angle of 0° In an embodiment of the present invention, after cutting with an end mill having a helical blade, the cut surface is further cut with an end mill with a blade angle of 0° as shown in FIG. This can correspond to a so-called finishing cut. With such a configuration, it is possible to suppress the peeling failure of the surface protection film and to suppress the tapered shape of the cut surface. More specifically, by cutting in a predetermined manner using an end mill having a twisted blade, the surface protective film is floated as described in section B-1 above, thereby suppressing poor peeling of the surface protective film. can do. On the other hand, when cutting with an end mill with a helical blade, the cut surface may become tapered, but by further cutting the cut surface with an end mill with a blade angle of 0°, such a tapered cut surface is eliminated. can do. Furthermore, on the cut surface side of the pressure-sensitive adhesive layer-attached optical laminate with an end mill having a twisted blade, there is a possibility that unacceptable deterioration in appearance quality may occur due to floating of the surface protective film. By cutting with an end mill, it is possible to remove such portions where the appearance quality has deteriorated. In addition, by cutting with an end mill having a blade angle of 0°, it is possible to appropriately adjust the floating amount of the surface protective film generated by cutting with an end mill having a helical blade. The amount of cutting by an end mill with a blade angle of 0° is preferably about 0.01 mm to 0.2 mm. Cutting with an end mill having a blade angle of 0° is finish cutting, and the cutting amount is typically significantly smaller than the cutting amount with an end mill having a helical edge (cutting amount for rough cutting). As a result, the floating amount of the surface protective film can be adjusted appropriately, and as a result, the surface protective film can be improved while maintaining the appearance quality within an allowable range without causing other problems. Peelability can be achieved. In addition, the production method of the present invention is also advantageous in terms of cost, since the end mill having a helical blade with high versatility contributes to most of the cutting. In this specification, "the blade angle is 0°" means that the blade edge 62a extends in a direction substantially parallel to the rotation axis, in other words, the blade is not twisted with respect to the rotation axis. . It should be noted that "0°" means substantially 0°, and includes the case where there is a slight angle twist due to processing error or the like. The term "tapered cut surface" means that the cut surface extends obliquely from the vertical direction when the cut surface is viewed from the lateral direction.

B-3-3. Others In one embodiment, the manufacturing method of the present invention includes cutting the outer peripheral surface of the workpiece non-linearly. Non-linear cutting includes forming recesses 4c including curved portions when the pressure-sensitive adhesive layer-attached optical layered body is viewed from above, for example, as shown in FIG. When producing an optical layered body with an adhesive layer having a planar view shape as shown in FIG. 8, the outer periphery of the work is cut linearly, and chamfered portions 4a and 4b are formed at two corners of the outer periphery of the work. A concave portion (a concave portion including a curved portion) 4c is formed in the central portion of the outer peripheral surface on which the chamfered portions 4a and 4b are formed. By forming such recesses, it is possible to cause the surface protective film to float in the vicinity of the recesses. As a result, it is possible to improve the peelability when peeling and removing the surface protective film from the concave portion. An example of such cutting will be described with reference to FIGS. 9(a) to 9(c). First, as shown in FIG. 9(a), the portion where the chamfered portion 4a of FIG. 8 is formed is chamfered, and then, as shown in FIG. 9(b), the portion where the chamfered portion 4b is formed is chamfered. processed. Finally, as shown in FIG. 9(c), recesses (recesses including curved portions) 4c are formed by cutting. The radius of the curved portion is preferably 5 mm or less, more preferably 4 mm or less, still more preferably 3 mm or less. The formation order (cutting order) of the chamfered portions 4a and 4b and the recessed portion 4c is not limited, and these may be formed in any appropriate order.

Cutting conditions can be appropriately set according to the desired shape. The rotation speed of the end mill having a helical blade and the end mill having a blade angle of 0° is preferably 1000 rpm to 60000 rpm, and more preferably 10000 rpm to 40000 rpm. The feed speed of the end mill with a helical blade and the end mill with a blade angle of 0° is preferably 500 mm/min to 10000 mm/min, more preferably 500 mm/min to 2500 mm/min. The number of cuts at the cut location can be one cut, two cuts, three cuts or more.

As described above, the cut optical layered body with an adhesive layer can be obtained. In the pressure-sensitive adhesive layer-attached optical layered body obtained by the production method of the present invention, peeling failure of the surface protective film is suppressed, and tapering of the cut surface is suppressed.

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

(1) Occurrence of Lifting of Surface Protective Film An arbitrary number (preferably 100 or more) of pressure-sensitive adhesive layer-attached optical laminates after cutting was prepared, and lifting of the surface protective film was observed using a magnifying glass or a microscope. The entire periphery of each adhesive layer-attached optical layered body was observed, and if a float of 1 μm or more was observed, the adhesive layer-attached optical layered body was counted as a sample with floatation, and "(sample with float/observed number). × 100" to calculate the floating rate.
(2) Peeling success rate Fifty optical laminates with pressure-sensitive adhesive layers obtained in Examples and Comparative Examples were randomly extracted, and the surface protective film was peeled off for each (triggering peeling force of 2 .9N). The number of times of peeling without problems out of 50 times of peeling was expressed as a percentage, and was defined as the peeling success rate.
(3) Floating amount The floating amount of the surface protective film in the cut optical laminates with pressure-sensitive adhesive layers obtained in Examples and Comparative Examples was measured with a magnifying glass or a microscope. The maximum value of the floating amount in one work was taken as the floating amount.
(4) Taper The cut surfaces of the pressure-sensitive adhesive layer-attached polarizing plates obtained in Examples and Comparative Examples were observed laterally with a scanning electron microscope (SEM) (magnification: 500). The cutting surface viewed from the lateral direction was evaluated according to the following criteria.
○: The cut surface was substantially extended in the vertical direction ×: The cut surface was shifted obliquely from the vertical direction

<Example 1>
According to a conventional method, the structure of surface protective film (60 μm) / cycloolefin protective film (47 μm) / polarizer (5 μm) / cycloolefin protective film (24 μm) / adhesive layer (20 μm) / separator in order from the viewing side. A polarizing plate with an adhesive layer was produced. As the surface protective film, a surface protective film having a configuration of PET substrate (50 μm)/PF adhesive layer (10 μm) was produced and verified. At that time, the storage elastic modulus of the adhesive layer (adhesive) was adjusted to 0.5 MPa to 3.0 MPa. The pressure-sensitive adhesive layer-attached polarizing plate obtained as described above was punched into a size of 5.7 inches (approximately 140 mm long and 65 mm wide), and a plurality of punched polarizing plates were laminated to form a work (total thickness of about 10 mm). The obtained workpiece is sandwiched between clamps (jigs), and an end mill is used to form chamfered portions at two corners of the outer periphery of the workpiece, and a concave portion (curved line) is formed at the center of the outer peripheral surface where the chamfered portions are formed A polarizing plate with a pressure-sensitive adhesive layer was obtained by forming a recessed portion including a recessed portion, and cutting the polarizing plate with an adhesive layer as shown in FIG. Cutting was performed twice for roughing and finishing. Rough cutting (first cutting) was performed using an end mill with a right-handed blade having a right-handed twist and a helix angle of 30° (discharge direction of cutting waste was upward), and the cutting amount was 0.2 mm. For finish cutting (second cutting), an end mill with a blade angle of 0° was used, and the cutting amount was 0.1 mm. The floating occurrence rate of the surface protection film by cutting was 100%. The evaluations (2) to (4) above were performed on the obtained cut polarizing plate with an adhesive layer. Table 1 shows the results.

<Example 2>
Cutting was performed in the same manner as in Example 1, except that an end mill with a right edge, right twist, and a twist angle of 45° was used for rough cutting (first cutting). The obtained cut polarizing plate with an adhesive layer was evaluated in the same manner as in Example 1. Table 1 shows the results.

<Comparative Example 1>
Cutting was performed in the same manner as in Example 1, except that finish cutting (second cutting) was not performed with an end mill having an edge angle of 0°. The obtained cut polarizing plate with an adhesive layer was evaluated in the same manner as in Example 1. Table 1 shows the results.

<Comparative Example 2>
Cutting was performed in the same manner as in Example 2, except that finish cutting (second cutting) was not performed with an end mill having an edge angle of 0°. The obtained cut polarizing plate with an adhesive layer was evaluated in the same manner as in Example 1. Table 1 shows the results.

<Comparative Example 3>
In the same manner as in Example 1, except that an end mill with a blade angle of 0° was used for rough cutting (first cutting), and an end mill with a right-hand edge right-hand twist and a helix angle of 30 ° was used for finishing (second cutting). I did cutting. The obtained cut polarizing plate with an adhesive layer was evaluated in the same manner as in Example 1. Table 1 shows the results.

<Comparative Example 4>
In the same manner as in Example 2, except that an end mill with a blade angle of 0° was used for rough cutting (first cutting), and an end mill with a right edge right twist and a helix angle of 45 ° was used for finishing (second cutting). I did cutting. The obtained cut polarizing plate with an adhesive layer was evaluated in the same manner as in Example 1. Table 1 shows the results.

<Comparative Example 5>
Cutting was performed in the same manner as in Example 1, except that an end mill with an edge angle of 0° was used for both rough cutting (first cutting) and finishing cutting (second cutting). The obtained cut polarizing plate with an adhesive layer was evaluated in the same manner as in Example 1. Table 1 shows the results.

<Comparative Example 6>
Cutting was performed in the same manner as in Example 1, except that an end mill with a right edge, right twist, and a twist angle of 30° was used for both rough cutting (first cutting) and finishing cutting (second cutting). The obtained cut polarizing plate with an adhesive layer was evaluated in the same manner as in Example 1. Table 1 shows the results.

<Comparative Example 7>
Cutting was performed in the same manner as in Example 1, except that an end mill with a right-hand edge, right-hand twist, and a twist angle of 45° was used for both rough cutting (first cutting) and finish cutting (second cutting). The obtained cut polarizing plate with an adhesive layer was evaluated in the same manner as in Example 1. Table 1 shows the results.

<Comparative Example 8>
Cutting was performed in the same manner as in Example 1, except that the polarizing plate with the pressure-sensitive adhesive layer was superimposed so that the separator was located on the lower side to form a work. The obtained cut polarizing plate with an adhesive layer was evaluated in the same manner as in Example 1. Table 1 shows the results.

<Comparative Example 9>
Cutting was performed in the same manner as in Example 2, except that the polarizing plate with the pressure-sensitive adhesive layer was superimposed so that the separator was located on the lower side to form a work. The obtained cut polarizing plate with an adhesive layer was evaluated in the same manner as in Example 1. Table 1 shows the results.

<Evaluation>
As is clear from Table 1, according to the examples of the present invention, a work is formed by stacking a plurality of optical laminates with pressure-sensitive adhesive layers, and an end mill is used to cut the outer peripheral surface of the work. In the method for manufacturing an optical laminate with an agent layer, after cutting the outer peripheral surface using an end mill having a helical blade, the cut surface is further cut using an end mill having a blade angle of 0°, and the end mill has a helical blade. By cutting the workpiece formed by stacking the adhesive layer-attached optical laminate so that the separator is positioned in the discharge direction of the cutting shavings, peeling failure of the surface protective film is suppressed and the cut surface is tapered. It is possible to easily and inexpensively realize a cut optical layered body with an adhesive layer, which is suppressed from becoming.

The manufacturing method of the present invention can be suitably used for manufacturing an optical layered body with a pressure-sensitive adhesive layer that requires cutting (especially non-linear processing). The pressure-sensitive adhesive layer-carrying optical layered body obtained by the production method of the present invention can be suitably used for an irregular-shaped image display part typified by automobile instrument panels and smart watches.

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

Claims (9)

forming a work by stacking a plurality of optical laminates with pressure-sensitive adhesive layers;
Cutting the outer peripheral surface of the work using an end mill having a helical blade; and
further cutting the outer peripheral surface of the cut work using an end mill with a blade angle of 0°;
including
The pressure-sensitive adhesive layer-attached optical laminate comprises an optical film, a pressure-sensitive adhesive layer disposed on one side of the optical film, a separator temporarily attached to the pressure-sensitive adhesive layer in a peelable manner, and another layer of the optical film. a surface protection film releasably temporarily attached to one side,
forming the workpiece by stacking the pressure-sensitive adhesive layer-attached optical layered body so that the separator is positioned in the discharge direction of the shavings of the end mill having the helical blade;
Cutting with an end mill having a helical blade causes the surface protective film to float ,
A method for producing a cut optical laminate with an adhesive layer. The end mill having the helical blade is a right-handed blade right-handed blade or a left-handed blade left-handed blade,
A work is formed by stacking the pressure-sensitive adhesive layer-attached optical layered body so that the separator is positioned on the upper side.
The manufacturing method according to claim 1. The end mill having the helical blade is a right-handed blade with a left-handed twist or a left-handed blade with a right-handed twist,
A workpiece is formed by stacking the pressure-sensitive adhesive layer-attached optical layered body so that the separator is located on the lower side.
The manufacturing method according to claim 1. 4. Any one of claims 1 to 3, wherein the cutting amount by the end mill having the helical blade is 0.1 mm to 0.5 mm, and the cutting amount by the end mill with the blade angle of 0° is 0.01 mm to 0.2 mm. Method of manufacture as described. The manufacturing method according to any one of claims 1 to 4 , wherein the floating amount of the surface protective film is 1 µm to 1000 µm. 6. The manufacturing method according to any one of claims 1 to 5 , comprising cutting the outer peripheral surface of the workpiece non-linearly. 7. The manufacturing method according to claim 6 , wherein the non-linear cutting includes forming a concave portion including a curved portion when the pressure-sensitive adhesive layer-attached optical layered body is viewed from above. 8. The manufacturing method according to claim 7 , wherein the curved portion has a radius of 5 mm or less. The manufacturing method according to any one of claims 1 to 8 , wherein the optical film is a polarizer or a polarizing plate.

Images