CN118721939A

CN118721939A - Method for producing optical laminate and optical laminate

Info

Publication number: CN118721939A
Application number: CN202410346444.4A
Authority: CN
Inventors: 松本大辅; 铃木到; 藤井幹士
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2023-03-28
Filing date: 2024-03-26
Publication date: 2024-10-01
Also published as: JP2024144049A; KR20240145895A; JP7515680B1

Abstract

The invention provides a method for manufacturing an optical laminate and an optical laminate, wherein the optical laminate has excellent processability and transportation. An optical laminate (10) comprising two optical films (11, 12) and an adhesive layer (13) sandwiched between the two optical films, at least one of the two optical films being a polarizing plate, wherein a convex portion protruding in the planar direction is provided on the side surface of the two optical films, the portion of the side surface of the adhesive layer (13) at a position corresponding to the position of the tip of the convex portion is located at a position inside the position of the tip of the convex portion, the adhesive layer (13) has a tan delta at 70 ℃ of 0.30 to 0.80, the adhesive has a storage modulus at 25 ℃ of 0.05 to 0.40MPa, and the adhesive layer (13) has a thickness of 50 [ mu ] m or more, and in the method for manufacturing the optical laminate (10), the longitudinal optical laminate is cut by a knife having a shape corresponding to the convex portion while pressing the vicinity of the cut edge of the longitudinal optical laminate.

Description

Method for producing optical laminate and optical laminate

Technical Field

The present invention relates to a method for producing an optical laminate and an optical laminate.

Background

Patent document 1 discloses: the side surface of the optical laminate including the adhesive layer is formed into a repeating structure having irregularities by cutting with a dicing blade having the repeating structure having irregularities. This can prevent the adhesive exposed on the side surface from being pulled out.

Prior art literature

Patent literature

Patent document 1: japanese patent No. 3523118

Disclosure of Invention

Problems to be solved by the invention

However, merely providing the side surface of the optical laminate with irregularities does not necessarily prevent the adhesive from overflowing the optical laminate properly. For example, when an adhesive having a thickness such as OCA (Optical CLEAR ADHESIVE) is used as an adhesive constituting an adhesive layer included in an Optical laminate, it is difficult to appropriately prevent the adhesive from overflowing. Since the OCA included as the adhesive layer of the optical laminate is generally soft and thick, if only the side surface of the optical laminate is uneven, when a plurality of products (chips) are cut out from the optical laminate in a longitudinal shape, the products cannot be separated one by one due to adhesion to adjacent products, or adhesive contamination is caused by adhesion to a conveyor belt guide or friction at the time of conveyance. In this way, in the optical laminate, there is a possibility that problems may occur in processability and transportation.

The present invention has been made in view of the above, and an object thereof is to provide a method for producing an optical laminate excellent in processability and transportation properties, and an optical laminate.

Solution for solving the problem

In order to achieve the above object, the present invention provides a method for producing an optical laminate, wherein the optical laminate comprises two optical films and an adhesive layer sandwiched between the two optical films, at least one of the two optical films is a polarizing plate, protrusions protruding in the surface direction of the optical films are provided on the side surfaces of the two optical films, the protrusions on the side surfaces of the two optical films are located at positions opposed to each other, a portion of the side surfaces of the adhesive layer at a position corresponding to the position of the tip of the protrusions is located at a position inside the position of the tip of the protrusions, tan δ at 70 ℃ of an adhesive constituting the adhesive layer is 0.30 to 0.80, and the adhesive layer has a storage modulus at 25 ℃ of 0.05 to 0.40MPa, and the adhesive layer has a thickness of 50 μm or more, and the optical laminate in the lengthwise direction of the lengthwise optical laminate is cut by a knife having a shape corresponding to the protrusions in the vicinity of the cut side of the lengthwise optical laminate sandwiched between the two optical films.

In the optical laminate manufactured by the method for manufacturing an optical laminate of the present invention, since the side surface of the adhesive layer is located inside the position of the tip of the convex portion of the optical film, it is possible to appropriately prevent the adhesive from overflowing from the optical laminate. Thus, according to the method for producing an optical laminate of the present invention, an optical laminate excellent in processability and transportation can be provided.

In order to properly and reliably manufacture the optical laminate, the method for manufacturing the optical laminate may have the following configuration.

The longitudinal optical laminate may be cut in a state where tension is applied to the longitudinal optical laminate in a direction substantially perpendicular to the cut edge and along the surface direction of the longitudinal optical laminate.

The angle of the cutting edge of the cutter may be 40 ° or more.

The elongated optical laminate may be cut in the 1 st direction by two substantially parallel knives, and after the cutting in the 1 st direction, the cut may be performed in the 2 nd direction so that a cut surface intersecting the cut surface in the 1 st direction can be formed.

The present invention also provides an optical laminate comprising two optical films and an adhesive layer sandwiched between the two optical films, wherein at least one of the two optical films is a polarizing plate, protrusions protruding in the plane direction of the optical films are provided on the side surfaces of the two optical films, the protrusions on the side surfaces of the two optical films are located at positions opposed to each other, a portion of the side surfaces of the adhesive layer at a position corresponding to the position of the tip of the protrusion is located at a position inside the position of the tip of the protrusion, tan delta at 70 ℃ of an adhesive constituting the adhesive layer is 0.30 to 0.80, and the adhesive has a storage modulus at 25 ℃ of 0.05 to 0.40MPa, and the thickness of the adhesive layer is 50 [ mu ] m or more.

In order to make the processability and transportation of the optical laminate more excellent, the optical laminate may have the following structure.

A concave portion may be provided adjacent to the convex portions on the side surfaces of the two optical films.

The convex portion and the concave portion may be provided continuously.

The convex angle formed by each line connecting the tip of the convex and the two ends of the convex may be 170 to 120 °, and the convex protrusion length, which is the length of the protrusion, may be 0.1 to 0.5mm.

The maximum difference between the tip of the convex portion and the side surface of the adhesive layer in the direction in which the convex portion protrudes may be 20 to 100 μm.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, an optical laminate excellent in processability and transportation can be provided.

Drawings

Fig. 1 is a side view of an end portion of an optical laminate according to an embodiment of the present invention.

Fig. 2 is a view showing an end portion of the optical laminate according to the embodiment of the present invention when the optical laminate is viewed from the lamination direction.

Fig. 3 is a schematic view schematically showing cutting (manufacturing) of an optical laminate from an elongated optical laminate.

Fig. 4 is a view showing a part of the edge of a dicing blade for dicing the elongated optical laminate.

Fig. 5 is a schematic view showing a dicing blade for dicing a longitudinal optical laminate.

Fig. 6 is a view showing various examples of pressing members used for cutting a longitudinal optical laminate.

Description of the reference numerals

10. An optical laminate; 11. 12, an optical film; 13. an adhesive layer; 20. an elongated optical laminate; 21. 22, an optical film; 23. an adhesive layer; 100. a cutter; 110. a plate-like member; 120. a pressurizing member.

Detailed Description

Hereinafter, a method for producing an optical laminate and an embodiment of the optical laminate according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and repetitive description thereof will be omitted. The dimensional ratios in the drawings do not necessarily match the dimensional ratios described.

Fig. 1 and 2 show an optical laminate 10 according to the present embodiment. The optical laminate 10 is formed by laminating a plurality of optical films. The optical laminate 10 includes an adhesive layer sandwiched between two optical films among a plurality of optical films. At least one of the two optical films is a polarizing plate. The optical laminate 10 shown in fig. 1 and 2 includes two optical films 11 and 12 and an adhesive layer 13 sandwiched between the two optical films 11 and 12. The optical laminate 10 is, for example, substantially rectangular when viewed in the lamination direction of the optical films. That is, the optical stack 10 has a substantially rectangular main surface. However, the shape of the main surface of the optical laminate 10 is not necessarily substantially rectangular.

Fig. 1 is a view showing an end portion of a side surface of the optical laminate 10, that is, a view when the end portion of the optical laminate 10 is viewed from a direction perpendicular to a lamination direction. Fig. 2 is a view showing an end portion of the main surface of the optical film 11, which is one of the main surfaces of the optical laminate 10, that is, a view when the end portion of the optical laminate 10 is viewed from the lamination direction of the optical films. In fig. 2, a portion of the adhesive layer 13 (hidden by the optical film 11) is indicated by a cross-hatching.

The optical stack 10 is, for example, a component for a display. In this case, the optical film 11 is a polarizing plate, and the optical film 12 is a protective film or a barrier film. The adhesive constituting the adhesive layer 13 is OCA. The (part of the) optical stack 10 is combined with a cover glass and an OLED (organic light emitting diode) to constitute a display. When the display is configured, the adhesive layer 13 composed of OCA is used for bonding the polarizing plate (optical film 11) and the cover glass.

The adhesive constituting the adhesive layer 13 may be an adhesive other than OCA.

The polarizing plate includes at least a polarizing plate, and generally includes a thermoplastic resin film adhered to one or both sides thereof. The polarizing plate may include a protective film or a release film on the surface opposite to the surface on which the adhesive layer 13 is laminated.

The thermoplastic resin film may be a protective film for protecting a polarizing plate, or the like. The protective film may be a retardation film or may be provided with a resin layer such as an antireflection treatment layer described below.

The thermoplastic resin films are each independently a film made of a thermoplastic resin having light transmittance. The thermoplastic resin constituting the thermoplastic resin film may be an optically transparent thermoplastic resin. The thermoplastic resin constituting the thermoplastic resin film may be, for example, a polyolefin resin such as a linear polyolefin resin (polypropylene resin or the like) or a cyclic polyolefin resin (norbornene resin or the like); cellulose resins such as triacetylcellulose and diacetylcellulose; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; a polycarbonate resin; (meth) acrylic resins such as methyl methacrylate resins; a polystyrene resin; polyvinyl chloride resin; acrylonitrile-butadiene-styrene based resin; acrylonitrile-styrene resin; a polyvinyl acetate resin; polyvinylidene chloride-based resins; a polyamide resin; polyacetal resin; modified polyphenylene ether resin; polysulfone-based resin; polyether sulfone resin; polyarylate-based resins; a polyamideimide resin; polyimide resin, and the like.

The thermoplastic resin film may have a resin layer laminated on the surface thereof. Examples of the resin layer are a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, an antifouling layer, and the like. The thermoplastic resin film can be adhered to the polarizer via an adhesive layer or an adhesive layer.

The thickness of the polarizing plate is usually 25 μm or more and 500 μm or less.

The protective film and the release film are films for protecting the surface of the polarizing plate, and are peelably bonded to the surface of the polarizing plate. The protective film and the release film can be composed of a base film and an adhesive layer laminated thereon. In the case of peeling the protective film from the polarizing plate, both the base film and the adhesive layer are peeled from the polarizing plate. When the release film is peeled from the polarizing plate, only the base film is peeled, and the adhesive layer remains on the surface of the polarizing plate.

The base film may be made of, for example, a polyolefin resin such as a polyethylene resin, a polypropylene resin, or a cyclic polyolefin resin; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; a polycarbonate resin; and (meth) acrylic resins. The base film may have a single-layer structure or a multilayer structure. The adhesive layer may be composed of a (meth) acrylic adhesive, an epoxy adhesive, a urethane adhesive, a silicone adhesive, or the like. The protective film may be a self-adhesive resin film such as a polypropylene resin or a polyethylene resin. In this case, the protective film does not have an adhesive layer.

The side surfaces of the two optical films 11 and 12 sandwiching the pressure-sensitive adhesive layer 13 are provided with convex portions (mountain portions) protruding in the surface direction of the optical films, and the convex portions (mountain portions) of the side surfaces of the two optical films 11 and 12 are located at positions facing each other. A concave portion (valley portion) may be provided adjacent to the convex portion on the side surface of the two optical films 11, 12. The convex and concave portions may be provided continuously.

As shown in fig. 2, a convex portion 11a protruding in the surface direction of the optical film is provided on the side surface of the optical film 11 when viewed from the lamination direction. The tip of the protruding portion 11a is curved. The convex portions 11a are continuously and periodically provided, and portions between the convex portions 11a are concave portions. The recess is also curved. Thus, the side surface of the optical film 11 has a wave shape. The end of the optical film 12 facing the optical film 11 is also formed in the same shape as the end of the optical film 11.

The projection angle (angle θ1 shown in fig. 2) formed by the lines connecting the tip of the projection 11a and the two ends of the projection 11a may be 170 to 120 °, and the projection length of the projection 11a, that is, the projection length may be 0.1 to 0.5mm (length L1 shown in fig. 2).

The adhesive constituting the adhesive layer 13 has a tan delta (loss coefficient of viscoelasticity) at 70 ℃ of 0.30 to 0.80 and a storage modulus at 25 ℃ of 0.05 to 0.40MPa. The adhesive may have a tan delta at 70 ℃ of 0.30 to 0.60 or 0.30 to 0.50. The storage modulus of the adhesive at 25 ℃ may be 0.05 to 0.30MPa or 0.05 to 0.20MPa. The thickness of the adhesive layer 13 is 50 μm or more. The thickness of the pressure-sensitive adhesive layer 13 may be 75 μm or more, or may be 100 μm or more.

A cylindrical test piece of an adhesive to be measured having a diameter of 8mm and a thickness of 600 μm was prepared for tan. Delta. At 70℃of the adhesive, and the test piece was measured at a temperature of 70℃using a dynamic viscoelasticity measuring device (Dynamic Analyzer RDA II: REOMETRIC Co., ltd.) with an initial strain of 1N by a torsional shearing method at a frequency of 1 Hz.

In general, when the thickness of the adhesive layer 13 is 50 μm or more, when a plurality of products (chips) are cut out from a longitudinal optical laminate, the products cannot be separated one by one due to adhesion to adjacent products, or defects related to workability and conveyability such as adhesive contamination caused by adhesion to a conveyor belt guide or friction during conveyance occur, but according to the present embodiment, an optical laminate excellent in workability and conveyability can be provided even when the thickness of the adhesive layer 13 is 50 μm or more. In particular, the above-described drawbacks occur more remarkably when the thickness of the adhesive layer 13 is 100 μm or more, but according to the present embodiment, an optical laminate excellent in processability and transportation can be provided even when the thickness of the adhesive layer 13 is 100 μm or more.

As shown in fig. 1 and 2, a portion of the side surface of the adhesive layer 13 at a position corresponding to the position of the tip of the convex portion of the optical film 11, 12 is located inside the position of the tip of the convex portion. That is, the pressure-sensitive adhesive layer 13 is recessed from the optical films 11 and 12 at the portions corresponding to the convex portions of the optical films 11 and 12. The side surface of the optical laminate 10 shown in fig. 1 is the side surface (cross section) of the tip of the convex portion of the optical films 11, 12. As shown in fig. 1 (a), the side surface of the adhesive layer 13 of this portion may be curved recessed with respect to the protruding direction of the convex portion as it is away from the optical films 11, 12 in the lamination direction of the optical films 11, 12. Alternatively, as shown in fig. 1 (b), the side surface of the adhesive layer 13 at this portion may be linear at a position recessed from the position of the tip end of the optical films 11, 12 in the lamination direction of the optical films 11, 12.

The maximum difference between the tip of the convex portion and the side surface of the adhesive layer 13 in the direction in which the convex portion of the optical films 11, 12 protrudes may be 20 to 100 μm. When a plurality of products (chips) are cut out from a longitudinal optical laminate, the maximum difference is preferably 60 to 100 μm from the viewpoint of easy separation of the products one by one, because the products adhere to adjacent products.

The side surface of the pressure-sensitive adhesive layer 13 in this portion is located further inside than the position of the tip of the convex portion of the optical films 11, 12 in the entire lamination direction of the optical films 11, 12. For example, as shown in fig. 1 (c), even if there is a portion on the side surface of the pressure-sensitive adhesive layer 13 located on the inner side than the position of the tip of the convex portion of the optical films 11, 12, the optical laminate 10 of the present embodiment is not present if there is a portion on the side surface of the pressure-sensitive adhesive layer 13 that is flush with the tip of the convex portion of the optical films 11, 12 or a portion protruding from the tip.

The above-described structure of the side surface of the optical laminate 10 is a structure extending over the entire side surface. However, the structure of the side surface of the optical stack 10 may be a partial structure of the side surface.

The above-described structure of the side face of the optical laminate 10 serves to appropriately prevent the adhesive from overflowing from the adhesive layer 13. The optical laminate 10 of the present embodiment is manufactured by cutting out an elongated optical laminate as will be described later. The optical laminate 10 may be a single-sheet-like small piece cut out from a long optical laminate that is a large-sized piece.

If the adhesive overflows from the optical laminate as described above, the optical laminate cannot be separated one by bonding with the adjacent optical laminate at the time of the dicing, or the adhesive may be contaminated by bonding with the conveyor guide or by friction at the time of the conveyance. With the above-described structure of the side surface of the optical laminate 10, such problems as workability and conveyability can be prevented. From the above point of view, the numerical value of the optical laminate 10 is a numerical value for forming an appropriate optical laminate 10.

The above problems may occur even if the pressure-sensitive adhesive layer for a polarizing plate is 50 μm or more. That is, the above-described problems may occur when the optical laminate includes even one adhesive layer of 50 μm or more.

Since the side surface of the optical laminate 10 of the present embodiment has irregularities, the side surface of the optical laminate 10 needs to be flattened depending on the product manufactured using the optical laminate 10. In this case, the side surface of the optical laminate 10 may be polished. In this case, the optical laminate 10 may have a size including a polishing margin (for example, 1 mm).

The above-described structure of the side surface of the optical laminate 10 is realized by the manufacturing method of the present embodiment. Next, a method for manufacturing the optical laminate 10 according to the present embodiment will be described. In the present manufacturing method, a long optical laminate that can be cut out of the optical laminate 10 is prepared in advance. The elongated optical laminate has the same laminate structure as the optical laminate 10. That is, in the present embodiment, the elongated optical laminate includes two optical films and an adhesive layer sandwiched between the two optical films as members. The two optical films and the adhesive layer constituting the longitudinal optical laminate are respectively identical in material to the two optical films 11, 12 and the adhesive layer 13 constituting the optical laminate 10. The elongated optical laminate has a size that allows the optical laminate 10 to be cut out when viewed from the lamination direction (in a plane perpendicular to the lamination direction).

In the manufacturing method of the present embodiment, the optical laminate 10 is cut out from the elongated optical laminate, and the optical laminate 10 is manufactured. For example, 4 sides of the optical stack 10 having a substantially rectangular main surface are cut from the elongated optical stack. In addition, a plurality of optical stacks 10 may be cut out from a longitudinal optical stack. The cut-out plurality of optical stacks 10 may be adjacent to each other.

The optical laminate 10 is cut from the elongated optical laminate by cutting portions of each side of the optical laminate 10 with a cutter. For example, as shown in fig. 3, the optical laminate 10 is cut by pressing the plate-like member 110 to which the dicing blade 100 is attached against the longitudinal optical laminate 20 while conveying the longitudinal optical laminate 20 (raw material). In the example shown in fig. 3, two optical stacks 10 are cut adjacently.

The dicing of each side of the optical laminate 10 with respect to the longitudinal optical laminate 20 need not be performed simultaneously on all sides. In the example shown in fig. 3, first, two sides parallel to the conveying direction are cut, and then, two sides perpendicular to the conveying direction are cut. As shown in fig. 3, the cutter 100 may be attached to the plate-like member 110 at a position corresponding to the cut edge. As shown in fig. 3, by attaching in advance to the plate-like member 110 both the dicing blade 100 that cuts two sides parallel to the conveyance direction and the dicing blade 100 that cuts two sides perpendicular to the conveyance direction, the dicing of each optical laminate 10 can be performed simultaneously.

As described above, in the manufacturing method of the present embodiment, the elongated optical layered body 20 may be cut in the 1 st direction (for example, a direction parallel to the conveyance direction) by the two substantially parallel cutting blades 100, and then cut in the 2 nd direction (for example, a direction perpendicular to the conveyance direction) so that a cutting surface intersecting with the cutting surface in the 1 st direction can be formed after cutting in the 1 st direction.

The dicing blade 100 for dicing the side of the optical laminate 10 is a blade having a shape corresponding to the convex portions of the two optical films 11, 12 of the optical laminate 10. For example, the cutting blade 100 is a wave blade. Fig. 4 shows a part of the edge of the dicing blade 100 as a wave-shaped blade, as viewed from the direction of pressing the elongated optical laminate 20. As shown in fig. 4, the cutting edge of the dicing blade 100 has a structure in which projections and depressions corresponding to the projections and depressions of the two optical films 11 and 12 of the optical laminate 10 are repeatedly formed. For example, as shown in fig. 4, the repeated pitch P of the cutting blade 100 is 2mm, and the protruding length L2 of the convex portion with respect to the concave portion is 0.3mm.

Fig. 5 schematically illustrates a dicing blade 100 for dicing the elongated optical layered body 20. The elongated optical laminate 20 is a laminate of optical films 21, 22 and an adhesive layer 23, which become the optical films 11, 12 and the adhesive layer 13 of the optical laminate 10. Fig. 5 is a view of the cutting blade 100 as seen from the longitudinal direction thereof, and the cut edge is the depth direction of the drawing. The angle θ2 of the cutting edge of the cutting blade 100 shown in fig. 5 may be 40 ° or more. The angle may be any of 45 ° or more, 50 ° or more, and 60 ° or more. As shown by the arrows in fig. 5, when the longitudinal optical laminate 20 is cut by the cutter 100, a stress in the transverse direction (in the plane direction) is applied to the longitudinal optical laminate 20 due to the taper of the cutter 100 (the angle of the edge).

In the manufacturing method of the present embodiment, the dicing of the elongated optical layered body 20 by the dicing blade 100 is performed in a state in which the vicinity of the dicing side of the elongated optical layered body 20 is pressurized. The pressing in the vicinity of the cut edge of the longitudinal optical laminate 20 is performed by pressing two pressing members 120 against the longitudinal optical laminate 20 at both ends of the cutter 100, for example, as shown in fig. 5. The pressurizing member 120 is an elastic body such as a sponge, for example. The pressing member 120 is a member longer than the cutting blade 100 (the length in the depth direction in fig. 5). The dicing of the elongated optical stack 20 may be performed without pressurizing the periphery in the vicinity of the dicing side of the elongated optical stack 20. For example, the dicing of the elongated optical layered body 20 may be performed in a state where only the vicinity of the dicing side of the elongated optical layered body 20 is pressurized.

The hardness of the elastomer used in the pressurization can be measured by a rubber durometer according to the SRIS-0101 physical test method of the Japanese rubber Association Standard specification, and is 20 to 60, further 20 to 35.

The pressing member 120 may be attached to the plate member 110 in advance, similarly to the cutting blade 100. For example, two pressing members 120 are attached to the plate member 110 so as to sandwich the cutting blade 100 for each cutting blade 100. When the dicing blade 100 is pressed against the elongated optical laminate 20, the pressing member 120 is pressed against both ends of the dicing side. The pressing in the vicinity of the cut edge may be performed by a method other than the pressing by the pressing member 120.

The pressing region may be a region of 15mm or less on each side of the cut edge. The pressing area may be 10mm or less on both sides of the cut edge. The pressure area may be 3mm or more on both sides of the cut edge. The pressure area may be 5mm or more on both sides of the cut edge. The distance may be a distance from the long side of the dicing blade 100 (the long side of the cutting blade 100 shown in fig. 4) that is in contact with the longitudinal optical laminate 20, instead of the distance from the dicing side. The pressure area may be an area near the cutting edge, and the area around the pressure area may be an area where pressure is not applied.

By cutting each side of the optical laminate 10 from the elongated optical laminate 20 in this manner, the optical laminate 10 (each side surface) cut by the cutting becomes the above-described structure.

In the manufacturing method of the present embodiment, the elongated optical laminate 20 may be cut in a state where tension is applied in a direction substantially perpendicular to the cut edge and along the surface direction of the elongated optical laminate 20. The tension is applied to appropriately cut the adhesive layer 23 by the cutter blade 100 and prevent the cut optical laminate 10 from reattaching to the elongated optical laminate 20 or another optical laminate 10. The direction in which the tension is applied is the direction in which the cut elongated optical stacks 20 are separated from each other. For example, in fig. 5, tension is applied in the left-right direction. The tension is applied, for example, by: both ends of the elongated optical laminate 20 in the direction in which tension is applied are held and one or both of the held portions are pulled. The tension may be applied by any other conventional method.

The biasing of the elongated optical laminate 20 to properly cut the adhesive layer 23 and prevent reattachment of the cut optical laminate 10 may be performed by a pressing member 120 (e.g., the above-described elastic body) for pressing the vicinity of the cut edge of the elongated optical laminate 20. For example, in order to achieve the above, as shown in fig. 6 (a) to 6 (d), the pressing member 120 is formed in a shape that is further away from the cutting blade 100 than the root of the cutting blade 100. Fig. 6 is a view of the cutting blade 100 as seen in the longitudinal direction, as in fig. 5.

For example, as shown in fig. 6 (a), the surface of the pressing member 120 on the side of the cutting blade 100 may be inclined so as to be away from the cutting blade 100 as going toward the tip of the cutting blade 100. As shown in fig. 6 (b), the angle of the tip of the pressurizing member 120 on the side of the cutting blade 100 may be C-chamfered. As shown in fig. 6 (c), the angle of the tip of the pressurizing member 120 on the side of the cutting blade 100 may be R-chamfered. In addition to the shape of the pressing member 120 on the side of the cutting blade 100, the surface of the pressing member 120 on the side opposite to the cutting blade 100 may be inclined so as to be away from the cutting blade 100 as going toward the tip of the cutting blade 100 as shown in fig. 6 (d).

By forming the pressing member 120 into the above-described shape, as shown in fig. 6 (e), when the pressing member 120 is pressed against the elongated optical laminate 20 when the elongated optical laminate 20 is cut by the dicing blade 100, the pressing member 120 is deformed away from the dicing blade 100. By this deformation, a force directed outward from the cut edge is applied to the longitudinal optical laminate 20 from the pressing member 120. This makes it possible to appropriately cut the adhesive layer 23 and prevent reattachment of the cut optical laminate 10.

In order to perform appropriate cutting, the surface of the pressing member 120 on the side of the cutting blade 100 shown in fig. 6 (d) and the like may have an angle (angle between a straight line extending from the edge of the blade to the right downward direction and the surface of the pressing member 120) that is distant from the cutting blade 100 as going toward the tip of the cutting blade 100, and may be 0 ° to 30 °. Or the angle may be further 5 deg. to 20 deg. for proper cutting. When a sponge is used as the pressurizing member 120, if the angle exceeds 30 °, the pressurizing member 120 weakens the force of pressurizing the elongated optical layered body 20.

The numerical value of the above-described manufacturing method of the optical laminate 10 is a numerical value for appropriately manufacturing the optical laminate 10. The above is a method for manufacturing the optical laminate 10 according to the present embodiment.

In the optical laminate 10 of the present embodiment, the side surface of the adhesive layer 13 is located inside the position of the tip of the convex portion of the optical films 11, 12, so that the adhesive can be appropriately prevented from overflowing from the optical laminate 10. Thus, the optical laminate 10 of the present embodiment is excellent in processability and transportation. For example, when manufacturing the optical laminate 10, the optical laminate 10 can be easily separated one by one. In addition, adhesion to the belt guide, glue contamination, and the like during conveyance can be prevented. In addition, the sticky feel of the optical laminate 10 during handling can be eliminated.

In order to further improve the workability and the transportation property of the optical laminate 10, the optical laminate 10 may have the following structure as in the above-described embodiment.

A concave portion may be provided adjacent to the convex portion of the side surfaces of the two optical films 11, 12. In addition, in the optical films 11, 12, the convex portions and the concave portions may be provided continuously. That is, the side surfaces of the optical films 11 and 12 may have a wave shape in which the convex portions and the concave portions are continuous. However, the two optical films 11 and 12 of the optical laminate 10 may have a structure in which at least 1 convex portion is provided.

The convex angle of each line connecting the tip of the convex and the both ends of the convex in the optical films 11, 12 may be 170 to 120 °, and the convex protrusion length, which is the length of the protrusion, may be 0.1 to 0.5mm. However, the protrusion angle and protrusion protruding length may not be included in the above ranges.

The maximum difference between the tip of the convex portion and the side surface of the adhesive layer in the direction in which the convex portion of the optical film 11, 12 protrudes may be 20 to 100 μm. But the maximum difference may not be included in the above range.

In addition, according to the method of manufacturing the optical laminate 10 of the present embodiment, the optical laminate 10 of the present embodiment can be manufactured.

In order to properly and reliably manufacture the optical laminate 10, the method of manufacturing the optical laminate 10 may have the following configuration as in the above-described embodiment.

The elongated optical laminate 20 may be cut in a state where tension is applied in a direction substantially perpendicular to the cut edge and along the plane direction of the elongated optical laminate 20. With this configuration, the dicing side is easily cut at the time of dicing the elongated optical layered body 20, and the optical layered body 10 can be separated from the elongated optical layered body 20 more appropriately. But does not necessarily require tension to be applied during cutting.

The angle of the cutting edge of the cutter 100 may be 40 ° or more. With this configuration, the elongated optical layered body 20 can be cut appropriately and reliably. However, the angle of the cutting edge of the cutting blade 100 may not be included in the above range.

The elongated optical layered body 20 is cut in the 1 st direction by two substantially parallel cutting knives 100, and then cut in the 2 nd direction so that a cutting surface intersecting the cutting surface in the 1 st direction can be formed. With this configuration, the optical laminate 10 can be cut out from the elongated optical laminate 20 appropriately and reliably. However, the dicing blade 100 is not necessarily required to perform dicing as described above.

Next, examples and comparative examples of the present embodiment will be described. In examples and comparative examples, the elongated optical laminate was cut into a plurality of substantially rectangular single-sheet optical laminates using a cutter. Next, a pen having a cushion rubber and a double-sided tape attached to the tip thereof was adhered to the main surface of the cut single-sheet optical laminate, and the single-sheet optical laminate was lifted in the vertical direction and moved to another place. At this time, the following was confirmed: whether or not the moving monolithic optical laminate is capable of moving in a state of 1 sheet to 1 sheet separation without being bonded to the adjacent monolithic optical laminate.

The maximum difference between the tip of the convex portion and the side surface of the adhesive layer in the direction in which the convex portion of the optical film protrudes, that is, the amount of the concave portion of the adhesive layer in the sheet-like optical laminate was measured. The measurement was performed using a microscope (VHX-5000, manufactured by Kidney Co., ltd.).

As the storage modulus of the adhesive layer, a cylindrical sheet having a diameter of 8mm and a thickness of 1mm was used as a test piece, and the measurement was performed by a torsional shear method at a frequency of 1Hz using a dynamic viscoelasticity measuring device (Dynamic Analyzer RDA II: REOMETRIC Co., ltd.) at a temperature of 23℃and a temperature of 80 ℃.

First, a longitudinal optical laminate was produced as follows. To 100 parts of water, 3 parts of carboxyl group-modified polyvinyl alcohol (KL-318 manufactured by Coley Co., ltd.) was dissolved, and 1.5 parts of a polyamide epoxy additive (Sumirez Resin 650 (30) manufactured by Sumika Chemtex Co., ltd.) as a water-soluble epoxy compound was added to the aqueous solution to prepare an aqueous adhesive (water-soluble adhesive).

A polyvinyl alcohol film having a thickness of 30 μm (average polymerization degree: about 2400, saponification degree: 99.9 mol% or more) was uniaxially stretched to about 5 times by dry stretching, then immersed in pure water at 60 ℃ for 1 minute while maintaining a stretched state, and then immersed in an aqueous solution having a weight ratio of iodine/potassium iodide/water of 0.05/5/100 at 28 ℃ for 60 seconds. Thereafter, the mixture was immersed in an aqueous solution having a weight ratio of potassium iodide/boric acid/water of 8.5/8.5/100 at 72℃for 300 seconds. Then, the film was washed with pure water at 26℃for 20 seconds, and then dried at 65℃to obtain a polarizing plate having iodine adsorbed and oriented on a polyvinyl alcohol film and having a thickness of 12. Mu.m.

The polarizing plate was obtained by laminating a transparent protective film (KC 2UA, thickness 25 μm, manufactured by Konica Minolta Co., ltd.) comprising triacetyl cellulose on one surface of the produced polarizing plate, and a transparent protective film (trade name "ZF14", thickness 23 μm, manufactured by ZEON Co., ltd.) comprising cycloolefin polymer on the other surface, using the above aqueous adhesive, and then drying at 80℃for 5 minutes. Before lamination, the transparent protective film made of triacetyl cellulose was subjected to saponification treatment, and the adhesive surface between the transparent protective film made of cycloolefin polymer and the polarizing plate was subjected to corona treatment.

Next, a commercially available adhesive was prepared. The commercially available adhesive is an adhesive having a release treated surface of a release treated protective film having a thickness of 100 μm formed with an adhesive layer of 220 μm. The pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer sandwiched between two optical films in a longitudinal optical laminate to be produced. The protective film is an optical film in which an adhesive layer is sandwiched together with the polarizing plate in the produced elongated optical laminate.

The transparent protective film made of triacetyl cellulose of the produced polarizing plate was laminated with an adhesive layer with a protective film on the surface thereof, to produce a longitudinal optical laminate. The produced elongated optical laminate was a laminate of a polarizing plate, an adhesive layer, and a protective film (corresponding to the optical film 11, the adhesive layer 13, and the optical film 12 in fig. 1, respectively).

Further, the storage modulus at 25℃of the commercially available adhesive was 0.06MPa, and the tan delta (loss tangent) at 70℃was 0.36. Thus, a longitudinal optical laminate having a width of 600mm and a length of 100m was produced.

In examples and comparative examples, the following cutting dies were prepared as cutting blades for cutting out a sheet-like optical laminate from a longitudinal optical laminate.

Cutting die A: a cutter mold was prepared in which 4 cutters (NCEW, commercial code 338216, manufactured by Nakayama, inc.) having repeated structures of wave-shaped irregularities were arranged in parallel at 153mm intervals. As a structure for pressurizing the longitudinal optical layered body, a sponge having a rectangular cross section and a sponge hardness of 35 (hardness measured by a rubber durometer according to SRIS-0101 physical test method of standard specifications of japan rubber association, hereinafter the same applies) and a sponge width of 7mm were disposed at both ends of the blade. In addition, the sponge was set to protrude 1.4mm from the tip of the knife.

Cutting die B: a die in which 8 knives (NCEW, commercial code 338216, manufactured by Nakayama, inc.) having a repeating structure of wave-shaped irregularities were arranged in parallel at 168mm intervals was prepared. As a structure for pressurizing the longitudinal optical layered body, a sponge having a rectangular cross section, a sponge hardness of 35, and a sponge width of 7mm was disposed at both ends of the knife. In addition, the sponge was set to protrude 1.4mm from the tip of the knife.

Cutting die C: a cutter mold was prepared in which 4 cutters (NCEW, commercial code 338216, manufactured by Nakayama, inc.) having repeated structures of wave-shaped irregularities were arranged in parallel at 153mm intervals. As a structure for pressurizing the longitudinal optical layered body, a sponge having a sponge hardness of 35 and a sponge width of 7mm, which is inclined outward toward the edge of the blade in the cross section as shown in fig. 6 (d), was disposed at both ends of the blade. In addition, the sponge was set to protrude 1.4mm from the tip of the knife. The angle between the straight line from the edge to the right downward direction and the straight line of the cross section of the sponge inclined outward toward the edge is 10 °.

Cutting die D: a die in which 8 knives (NCEW, commercial code 338216, manufactured by Nakayama, inc.) having a repeating structure of wave-shaped irregularities were arranged in parallel at 168mm intervals was prepared. As a structure for pressurizing the longitudinal optical layered body, a sponge having a sponge hardness of 35 and a sponge width of 7mm, which is inclined outward toward the edge of the blade in the cross section as shown in fig. 6 (d), was disposed at both ends of the blade. In addition, the sponge was set to protrude 1.4mm from the tip of the knife. The angle between the straight line from the edge to the right downward direction and the straight line of the cross section of the sponge inclined outward toward the edge is 10 °.

Cutting die E: a cutter mold was prepared in which 4 cutters (NCEW, commercial code 338216, manufactured by Nakayama, inc.) having repeated structures of wave-shaped irregularities were arranged in parallel at 153mm intervals. As a structure for pressurizing the longitudinal optical layered body, a sponge having a rectangular cross section and a sponge hardness of 35 was disposed without a gap in a region where no knife was present. In addition, the sponge was set to protrude 1.4mm from the tip of the knife.

Cutting die F: a die in which 8 knives (NCEW, commercial code 338216, manufactured by Nakayama, inc.) having a repeating structure of wave-shaped irregularities were arranged in parallel at 168mm intervals was prepared. As a structure for pressurizing the longitudinal optical layered body, a sponge having a rectangular cross section and a sponge hardness of 35 was disposed without a gap in a region where no knife was present. In addition, the sponge was set to protrude 1.4mm from the tip of the knife.

Cutting die G: a cutter mold was prepared in which 4 cutters (NCEW, commercially available from Nakayama, inc. 338216) having a repeating structure of wave-shaped irregularities were arranged in parallel at 168mm intervals.

Cutting die H: a die in which 8 knives (NCEW, commercial code 338216, manufactured by Nakayama, inc.) having a repeating structure of wave-shaped irregularities were arranged in parallel at 168mm intervals was prepared.

The dies G and H are not provided with a structure for pressurizing the elongated optical layered body such as a sponge.

As example 1, the manufactured elongated optical laminate was cut using a cutting die a while being conveyed and stopped. As the knife of the knife mold a, a knife disposed parallel to the conveyance direction of the elongated optical layered body was used. Next, the elongated optical laminate is cut using a cutting die B. As the knife of the knife mold B, a knife disposed perpendicularly to the conveyance direction of the elongated optical layered body was used. The optical laminate thus cut was a substantially rectangular optical laminate of 153mm×168mm, and 21 sheets of optical laminate were obtained. All the optical laminates after cutting were not adhered to the adjacent optical laminate, and the produced optical laminate was excellent in separability. The adhesive layer has a recess of 20 to 50 [ mu ] m in the direction in which the convex portion of the optical film protrudes.

As example 2, the manufactured elongated optical laminate was cut using a cutting die C while being conveyed and stopped. As the knife of the knife mold C, a knife disposed parallel to the conveyance direction of the elongated optical layered body is used. Next, the elongated optical laminate is cut using a cutting die D. The knife of the die D is disposed so as to be perpendicular to the conveyance direction of the elongated optical layered body. The optical laminate thus cut was a substantially rectangular optical laminate of 153mm×168mm, and 21 sheets of optical laminate were obtained. All the optical laminates after cutting are not adhered to the adjacent optical laminates, and the separability of the manufactured optical laminate is better. The adhesive layer has a recess of 60 to 100 [ mu ] m in the direction in which the convex portion of the optical film protrudes.

As comparative example 1, the manufactured elongated optical laminate was cut using a cutting die E while being conveyed and stopped. As the knife of the knife mold E, a knife disposed parallel to the conveyance direction of the elongated optical layered body is used. Next, the elongated optical laminate is cut using a cutting die F. As the knife of the knife mold F, a knife disposed perpendicularly to the conveyance direction of the elongated optical layered body is used. The optical laminate thus cut was a substantially rectangular optical laminate of 153mm×168mm, and 21 sheets of optical laminate were obtained. All the optical laminates after cutting are in a state of being reattached to adjacent optical laminates and connected together, and the separability of the manufactured optical laminate is poor. The depressions of the adhesive layer in the direction in which the protrusions of the optical film protrude were not confirmed. As described above, since the plurality of optical stacks are connected together, the adhesive layer of the convex portion can be considered to be flush or protruding.

As comparative example 2, the manufactured elongated optical laminate was cut using a cutting die G in a state where the elongated optical laminate was conveyed and stopped. As the knife of the knife die G, a knife disposed parallel to the conveyance direction of the elongated optical layered body is used. Next, the elongated optical laminate is cut using a cutting die H. The knife of the knife mold H is disposed so as to be perpendicular to the conveyance direction of the elongated optical layered body. The optical laminate thus cut was not separated from the die after cutting, and therefore a substantially rectangular optical laminate of 153mm×168mm could not be recovered.

The method for producing an optical laminate and the optical laminate of the present invention have the following structures.

[1] A method for producing an optical laminate, wherein the optical laminate comprises two optical films and an adhesive layer sandwiched between the two optical films, at least one of the two optical films is a polarizing plate, protrusions protruding in the plane direction of the optical films are provided on the side surfaces of the two optical films, the protrusions on the side surfaces of the two optical films are located at positions opposed to each other, a portion of the side surfaces of the adhesive layer at a position corresponding to the position of the tip of the protrusions is located at a position inside the position of the tip of the protrusions, the adhesive layer has a tan delta at 70 ℃ of 0.30 to 0.80, the adhesive layer has a storage modulus at 25 ℃ of 0.05 to 0.40MPa, and the adhesive layer has a thickness of 50 [ mu ] m or more, and the optical laminate having a shape corresponding to the protrusions is cut in the longitudinal direction by a knife in the vicinity of the longitudinal optical laminate having a shape corresponding to the protrusions.

[2] The production method according to [1], wherein the elongated optical laminate is cut in a state in which tension is applied in a direction substantially perpendicular to the cut edge and along the surface direction of the elongated optical laminate.

[3] The production method according to [1] or [2], wherein the angle of the edge of the blade is 40 ° or more.

[4] The production method according to any one of [1] to [3], wherein the elongated optical laminate is cut in the 1 st direction by two substantially parallel knives, and after the cutting in the 1 st direction, the elongated optical laminate is cut in the 2 nd direction so that a cut surface intersecting the cut surface in the 1 st direction can be formed.

[5] An optical laminate comprising two optical films and an adhesive layer sandwiched between the two optical films, wherein at least one of the two optical films is a polarizing plate, protrusions protruding in the plane direction of the optical films are provided on the side surfaces of the two optical films, the protrusions on the side surfaces of the two optical films are located at positions opposed to each other, a portion of the side surfaces of the adhesive layer at a position corresponding to the position of the tip of the protrusion is located at a position on the inner side than the position of the tip of the protrusion, tan delta at 70 ℃ of an adhesive constituting the adhesive layer is 0.30 to 0.80, storage modulus at 25 ℃ of the adhesive is 0.05 to 0.40MPa, and the thickness of the adhesive layer is 50 [ mu ] m or more.

[6] The optical laminate according to [5], wherein a concave portion is provided adjacent to the convex portion of the side surfaces of the two optical films.

[7] The optical laminate according to [6], wherein the convex portion and the concave portion are continuously provided.

[8] The optical laminate according to any one of [5] to [7], wherein a convex angle formed by each line connecting the tip of the convex portion and both ends of the convex portion is 170 to 120 °, and a convex protrusion length, which is a length of protrusion of the convex portion, is 0.1 to 0.5mm.

[9] The optical laminate according to any one of [5] to [8], wherein a maximum difference between a tip of the convex portion and a side surface of the adhesive layer in a direction in which the convex portion protrudes is 20 to 100 μm.

Claims

1. A method for producing an optical laminate, wherein,

The optical laminate comprises two optical films and an adhesive layer sandwiched by the two optical films,

At least one of the two optical films is a polarizing plate,

The side surfaces of the two optical films are provided with convex parts protruding towards the surface direction of the optical films, the convex parts of the side surfaces of the two optical films are positioned at the opposite positions,

A portion of the side surface of the adhesive layer at a position corresponding to the position of the tip of the convex portion is located at a position inside the position of the tip of the convex portion,

The adhesive agent constituting the adhesive agent layer has a tan delta at 70 ℃ of 0.30 to 0.80 and a storage modulus at 25 ℃ of 0.05 to 0.40MPa,

The thickness of the adhesive layer is 50 μm or more,

The elongated optical laminate is cut in the lamination direction of the elongated optical laminate by a knife having a shape corresponding to the convex portion in a state where the vicinity of the cut edge of the elongated optical laminate including the two optical films and the adhesive layer sandwiched between the two optical films is pressurized.

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

The longitudinal optical laminate is cut in a state where tension is applied in a direction substantially perpendicular to the cut edge and along a plane direction of the longitudinal optical laminate.

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

The angle of the knife tip of the knife is more than 40 degrees.

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

The elongated optical laminate is cut in the 1 st direction by two substantially parallel knives, and after the cutting in the 1 st direction, the elongated optical laminate is cut in the 2 nd direction so that a cut surface intersecting the cut surface in the 1 st direction can be formed.

5. An optical laminate comprising two optical films and an adhesive layer sandwiched by the two optical films, wherein,

At least one of the two optical films is a polarizing plate,

The thickness of the adhesive layer is 50 μm or more.

6. The optical stack according to claim 5, wherein,

A concave portion is provided adjacent to the convex portion of the side surfaces of the two optical films.

7. The optical stack according to claim 6, wherein,

The convex portion and the concave portion are provided continuously.

8. The optical stack according to any one of claims 5 to 7, wherein,

The angle of the convex portion formed by each line connecting the tip of the convex portion and the two ends of the convex portion is 170-120 DEG, and the protruding length of the convex portion is 0.1-0.5 mm.

9. The optical stack according to any one of claims 5 to 7, wherein,

The maximum difference between the tip of the convex portion and the side surface of the adhesive layer in the direction in which the convex portion protrudes is 20 to 100 μm.