CN118721939A - Method for producing optical laminate and optical laminate - Google Patents

Abstract

The present invention provides a method for manufacturing an optical laminate and an optical laminate, which has excellent processability and transportability. The optical laminate (10) comprises two optical films (11, 12) and an adhesive layer (13) sandwiched by the two optical films, at least one of the two optical films is a polarizing plate, convex portions protruding in the surface direction are provided on the side surfaces of the two optical films, a portion of the side surface of the adhesive layer (13) corresponding to the position of the top of the convex portion is located at a position closer to the inside than the position of the top of the convex portion, the adhesive constituting the adhesive layer (13) has a tanδ of 0.30 to 0.80 at 70°C, and a storage modulus of 0.05 to 0.40 MPa at 25°C, and the thickness of the adhesive layer (13) is 50 μm or more. 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 pressurizing 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 layered body and the optical layered body.

Background Art

Patent Document 1 discloses that the side surface of an optical laminate including an adhesive layer has a repetitive structure of projections and recesses by cutting with a cutter having a repetitive structure of projections and recesses, thereby preventing the adhesive exposed at the side surface from being pulled out.

Prior art literature

Patent Literature

Patent Document 1: Japanese Patent No. 3523118

Summary of the invention

Problem that the invention aims to solve

However, simply making the side of the optical stack concavoconvex may not be able to properly prevent the adhesive from overflowing from the optical stack. For example, when using an adhesive having a thickness such as OCA (Optical Clear Adhesive) as the adhesive constituting the adhesive layer included in the optical stack, it is difficult to properly prevent the adhesive from overflowing. OCA included as the adhesive layer of the optical stack is generally soft and thick. Therefore, if the side of the optical stack is simply made concavoconvex, when multiple products (small pieces) are cut out from the longitudinal optical stack, they will not be able to be separated one by one due to adhesion to adjacent products, or they will adhere to the conveyor belt guide or cause adhesive contamination due to friction during transportation. In this way, problems may arise in the processability and conveyance of the optical stack.

The present invention has been made in view of the above, and an object of the present invention is to provide a method for producing an optical layered body having excellent processability and conveyability, and an optical layered body.

Solutions for solving problems

In order to achieve the above-mentioned purpose, the present invention provides a method for manufacturing 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, and convex portions protruding in the surface direction of the optical films are provided on the sides of the two optical films, the convex portions on the sides of the two optical films are located relative to each other, and a portion of the side of the adhesive layer at a position corresponding to the position of the top of the convex portion is located closer to the inside than the position of the top of the convex portion, the adhesive constituting the adhesive layer has a tanδ of 0.30 to 0.80 at 70°C, and a storage modulus of 0.05 to 0.40 MPa at 25°C, and a thickness of the adhesive layer is greater than 50 μm, and while pressurizing the vicinity of the cutting edge of the longitudinal optical laminate comprising the two optical films and the adhesive layer sandwiched by the two optical films, the longitudinal optical laminate is cut along the stacking direction of the longitudinal optical laminate using a knife having a shape corresponding to the convex portion.

In the optical laminate manufactured by the manufacturing method of the optical laminate of the present invention, since the side surface of the adhesive layer is located at a position closer to the inside than the top of the convex portion of the optical film, it is possible to appropriately prevent the adhesive from overflowing from the optical laminate. Therefore, according to the manufacturing method of the optical laminate of the present invention, an optical laminate with excellent processability and transportability can be provided.

In order to appropriately and reliably manufacture the optical layered body, the method for manufacturing the optical layered body may have the following structure.

The longitudinal optical layered body may be cut while tension is applied in a direction substantially perpendicular to the cutting side and along the surface direction of the longitudinal optical layered body.

The angle of the blade tip of the knife may be 40° or more.

The longitudinal optical layered body may be cut in the first direction by two substantially parallel knives, and after cutting in the first direction, cut in the second direction so as to form a cut surface intersecting with the cut surface in the first direction.

In addition, the present invention provides an optical laminate, which includes 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, and convex portions protruding in the surface direction of the optical films are provided on the side surfaces of the two optical films, the convex portions on the side surfaces of the two optical films are located relative to each other, and a portion of the side surface of the adhesive layer corresponding to the position of the top end of the convex portion is located closer to the inside than the position of the top end of the convex portion, the adhesive constituting the adhesive layer has a tanδ of 0.30 to 0.80 at 70°C, and a storage modulus of 0.05 to 0.40 MPa at 25°C, and the thickness of the adhesive layer is greater than 50 μm.

In order to make the processability and conveyability of the optical layered body more excellent, the optical layered body may have the following structure.

The recessed portions may be provided adjacent to the raised 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 top end of the convex portion and both ends of the convex portion may be 170 to 120 degrees, and the convex protrusion length, which is the length of the convex portion protruding, may be 0.1 to 0.5 mm.

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

Effects of the Invention

According to the present invention, an optical layered body having excellent processability and transportability can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an end portion of an optical layered body according to an embodiment of the present invention when viewed from the side.

FIG. 2 is a diagram showing an end portion of the optical layered body according to the embodiment of the present invention when viewed from the lamination direction.

FIG. 3 is a diagram schematically showing cutting (manufacturing) of an optical layered body from a longitudinal optical layered body.

FIG. 4 is a diagram showing a part of the blade tip of a cutting knife used for cutting the longitudinal optical layered body.

FIG. 5 is a diagram schematically showing a cutting knife when cutting a longitudinal optical layered body.

FIG. 6 is a diagram showing various examples of a pressurizing member used for cutting a longitudinal optical layered body.

Description of Reference Numerals

10. Optical laminate; 11, 12. Optical film; 13. Adhesive layer; 20. Long optical laminate; 21, 22. Optical film; 23. Adhesive layer; 100. Cutting knife; 110. Plate-shaped member; 120. Pressurizing member.

DETAILED DESCRIPTION

Hereinafter, the manufacturing method of the optical laminate of the present invention and the embodiment of the optical laminate are described in detail in conjunction with the accompanying drawings. In addition, in the description of the accompanying drawings, the same reference numerals are marked on the same elements, and repeated descriptions are omitted. In addition, the dimensional ratios of the accompanying drawings are not necessarily consistent with the dimensional ratios of the description.

An optical laminate 10 of the present embodiment is shown in FIGS. 1 and 2 . The optical laminate 10 is formed by laminating a plurality of optical films. The optical laminate 10 includes an adhesive layer sandwiched by two of the plurality of optical films. At least one of the two optical films is a polarizing plate. The optical laminate 10 shown in FIGS. 1 and 2 includes two optical films 11, 12 and an adhesive layer 13 sandwiched by the two optical films 11, 12. The optical laminate 10 is, for example, roughly rectangular when viewed from the lamination direction of the optical films. That is, the optical laminate 10 has a roughly rectangular main surface. However, the shape of the main surface of the optical laminate 10 is not necessarily roughly rectangular.

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

The optical laminate 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 an isolation film. The adhesive constituting the adhesive layer 13 is OCA. The optical laminate 10 (part of it) is combined with a glass cover and an OLED (organic light emitting diode) to form a display. When constituting a display, the adhesive layer 13 composed of OCA is used to bond the polarizing plate (optical film 11) to the glass cover.

In addition, 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 further includes a thermoplastic resin film bonded to one or both sides thereof. In addition, the polarizing plate may include a protective film or a separator 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, etc. The protective film may be a retardation film, and may be provided with a resin layer such as an antireflection treatment layer described below.

The thermoplastic resin film is independently a film composed 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 chain polyolefin resin (polypropylene resin, etc.) and a cyclic polyolefin resin (norbornene resin, etc.); a cellulose resin such as triacetyl cellulose and diacetyl cellulose; a polyester resin such as polyethylene terephthalate and polybutylene terephthalate; a polycarbonate resin; a (meth) acrylic resin such as methyl methacrylate resin; a polystyrene resin; a polyvinyl chloride resin; an acrylonitrile-butadiene-styrene resin; an acrylonitrile-styrene resin; a polyvinyl acetate resin; a polyvinylidene chloride resin; a polyamide resin; a polyacetal resin; a modified polyphenylene ether resin; a polysulfone resin; a polyethersulfone resin; a polyarylate resin; a polyamideimide resin; a polyimide resin, etc.

The thermoplastic resin film may have a resin layer laminated on its surface. Examples of the resin layer are a hard coat layer, an anti-glare layer, an anti-reflection layer, an antistatic layer, an antifouling layer, etc. The thermoplastic resin film can be bonded to the polarizer via an adhesive layer or a pressure-sensitive adhesive layer.

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

The protective film and the isolation film are films for protecting the surface of the polarizing plate, and are releasably adhered to the surface of the polarizing plate. The protective film and the isolation film can be composed of a substrate film and an adhesive layer laminated thereon. When the protective film is peeled off from the polarizing plate, both the substrate film and the adhesive layer are peeled off from the polarizing plate. When the isolation film is peeled off from the polarizing plate, only the substrate film is peeled off, and the adhesive layer remains on the surface of the polarizing plate.

The substrate film may be composed of, for example, polyolefin resins such as polyethylene resins, polypropylene resins, and cyclic polyolefin resins; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polycarbonate resins; (meth) acrylic resins, etc. The substrate film may be a single-layer structure or a multi-layer structure. The adhesive layer may be composed of (meth) acrylic adhesives, epoxy adhesives, urethane adhesives, silicone adhesives, etc. In addition, the protective film may be a self-adhesive resin film such as polypropylene resins and polyethylene resins. 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 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) on the side surfaces of the two optical films 11 and 12 are located at positions opposite to each other. Concave portions (valley portions) may also be provided adjacent to the convex portions on the side surfaces of the two optical films 11 and 12. The convex portions and the concave portions may be provided continuously.

As shown in FIG. 2 , when viewed from the stacking direction, a convex portion 11a protruding toward the surface direction of the optical film is provided on the side surface of the optical film 11. The top of the convex portion 11a is in a curved shape. The convex portions 11a are provided continuously and periodically, and the portion between the convex portions 11a is a concave portion. The concave portion is also in a curved shape. In this way, the side surface of the optical film 11 is in a wave-like shape. In addition, the end portion of the optical film 12 opposite to the optical film 11 is also in the same shape as the end portion of the optical film 11.

The convex angle formed by the lines connecting the top of the convex portion 11a and the two ends of the convex portion 11a (angle θ1 shown in Figure 2) can be 170~120°, and the protruding length of the convex portion 11a, that is, the convex protrusion length, can be 0.1~0.5mm (length L1 shown in Figure 2).

The tanδ (loss coefficient of viscoelasticity) of the adhesive constituting the adhesive layer 13 at 70°C is 0.30 to 0.80, and the storage modulus of the adhesive at 25°C is 0.05 to 0.40 MPa. The tanδ of the adhesive at 70°C can be 0.30 to 0.60, or 0.30 to 0.50. The storage modulus of the adhesive at 25°C can be 0.05 to 0.30 MPa, or 0.05 to 0.20 MPa. The thickness of the adhesive layer 13 is 50 μm or more. The thickness of the adhesive layer 13 can be 75 μm or more, or 100 μm or more.

Regarding the tanδ of the adhesive at 70°C, a cylindrical test piece of 8 mm in diameter × 600 μm in thickness consisting of the adhesive to be measured was prepared, and the measurement was performed using a dynamic viscoelasticity measuring apparatus (Dynamic Analyzer RDA II: manufactured by REOMETRIC Co., Ltd.) using a torsional shear method with a frequency of 1 Hz and an initial strain of 1 N at a temperature of 70°C.

Generally, when the thickness of the adhesive layer 13 is 50 μm or more, when a plurality of products (small pieces) are cut out from a longitudinal optical laminate, 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 during transportation, etc., which may cause problems related to processability and transportability. However, according to this embodiment, even if the thickness of the adhesive layer 13 is 50 μm or more, an optical laminate with excellent processability and transportability can be provided. In particular, when the thickness of the adhesive layer 13 is 100 μm or more, the above-mentioned problems occur more significantly, but according to this embodiment, even if the thickness of the adhesive layer 13 is 100 μm or more, an optical laminate with excellent processability and transportability can be provided.

As shown in Fig. 1 and Fig. 2, the part of the side surface of the adhesive layer 13 corresponding to the position of the top of the convex portion of the optical films 11 and 12 is located at a position closer to the inside than the position of the top of the convex portion. That is, in the part corresponding to the convex portion of the optical films 11 and 12, the adhesive layer 13 is recessed compared to 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 top of the convex portion of the optical films 11 and 12. As shown in Fig. 1 (a), the side surface of the adhesive layer 13 of this part can be recessed in a curve relative to the protruding direction of the convex portion as it moves away from the optical films 11 and 12 in the stacking direction of the optical films 11 and 12. Alternatively, as shown in Fig. 1 (b), the side surface of the adhesive layer 13 of this part can be straight at a position recessed from the top of the optical films 11 and 12 in the stacking direction of the optical films 11 and 12.

The maximum difference between the top of the convex portion of the optical film 11, 12 and the side surface of the adhesive layer 13 in the direction of the convex portion protruding can be 20 to 100 μm. When a plurality of products (small pieces) are cut out from the longitudinal optical laminate, they will adhere to adjacent products. Therefore, from the viewpoint of easy separation of products one by one, the above-mentioned maximum difference is preferably 60 to 100 μm.

The side surface of the adhesive layer 13 in this part is located inside the top of the convex portion of the optical films 11 and 12 in the entire lamination direction of the optical films 11 and 12. For example, as shown in FIG1(c), even if there is a part located inside the top of the convex portion of the optical films 11 and 12 on the side surface of the adhesive layer 13, as long as there is a part flush with the top of the convex portion of the optical films 11 and 12 on the side surface of the adhesive layer 13 or a part protruding from the top, it is not the optical laminated body 10 of the present embodiment.

The above-mentioned structure of the side surface of the optical layered body 10 is a structure extending over the entire side surface. However, the above-mentioned structure of the side surface of the optical layered body 10 may be a structure of only a part of the side surface.

The above-mentioned structure of the side of the optical laminate 10 is used to appropriately prevent the adhesive from overflowing from the adhesive layer 13. The optical laminate 10 of this embodiment is manufactured by cutting out from the longitudinal optical laminate as described later. The optical laminate 10 can also be a single-piece small piece cut out from the longitudinal optical laminate as a large-size piece.

If the adhesive overflows from the optical laminate as described above, the optical laminate cannot be separated one by one due to adhesion to the adjacent optical laminate when cutting, or adhesive contamination is caused by adhesion to the conveyor belt guide or friction during transportation. The above structure of the side surface of the optical laminate 10 can prevent such problems of processability and transportability. From the above viewpoint, the numerical values of the optical laminate 10 are numerical values for forming an appropriate optical laminate 10.

Even if the pressure-sensitive adhesive layer for the polarizing plate is 50 μm or more, the above-mentioned problem may occur. In other words, if the optical laminate includes even one pressure-sensitive adhesive layer of 50 μm or more, the above-mentioned problem may occur.

Since the side surface of the optical laminate 10 in the present embodiment has projections and depressions, it is necessary to make the side surface of the optical laminate 10 flat, depending on the product manufactured using the optical laminate 10. In this case, it is sufficient to grind the side surface of the optical laminate 10. In this case, the size of the optical laminate 10 only needs to include the grinding allowance (e.g., 1 mm).

The above-mentioned structure of the side of the optical stack 10 is achieved by the manufacturing method of the present embodiment. Next, the manufacturing method of the optical stack 10 of the present embodiment is described. In the present manufacturing method, a longitudinal optical stack from which the optical stack 10 can be cut out is prepared in advance. The longitudinal optical stack has the same stacking structure as the optical stack 10. That is, in the present embodiment, the longitudinal optical stack includes two optical films and an adhesive layer sandwiched by the two optical films as components. The two optical films and the adhesive layer constituting the longitudinal optical stack are respectively the same in material as the two optical films 11, 12 and the adhesive layer 13 constituting the optical stack 10. The longitudinal optical stack has a size that allows the optical stack 10 to be cut out when observed from the stacking direction (in a plane perpendicular to the stacking direction).

In the manufacturing method of this embodiment, the optical stack 10 is cut out from the longitudinal optical stack to manufacture the optical stack 10. For example, the four sides of the optical stack 10 of the substantially rectangular main surface are cut out from the longitudinal optical stack. In addition, a plurality of optical stacks 10 may be cut out from the longitudinal optical stack. The cut plurality of optical stacks 10 may be adjacent to each other.

The optical stack 10 is cut out from the longitudinal optical stack by cutting the portions of the sides of the optical stack 10 with the cutting knife. For example, as shown in Fig. 3, the optical stack 10 is cut out by pressing a plate-like member 110 with the cutting knife 100 attached to the longitudinal optical stack 20 while conveying the longitudinal optical stack 20 (raw material). In the example shown in Fig. 3, two optical stacks 10 are cut out adjacent to each other.

The cutting of each side of the optical stack 10 relative to the longitudinal optical stack 20 does not have to be carried out on all sides at the same time. In the example shown in FIG3, first, the two sides parallel to the conveying direction are cut, and then the two sides perpendicular to the conveying direction are cut. As shown in FIG3, it is sufficient as long as a cutting knife 100 is installed at a position of the plate-like member 110 corresponding to the edge to be cut. As shown in FIG3, by pre-installing a cutting knife 100 for cutting two sides parallel to the conveying direction and a cutting knife 100 for cutting two sides perpendicular to the conveying direction on the plate-like member 110, it is possible to cut each optical stack 10 at the same time.

Thus, in the manufacturing method of this embodiment, the longitudinal optical layered body 20 can be cut along a first direction (for example, a direction parallel to the conveying direction) using two approximately parallel cutting knives 100, and after cutting along the first direction, it can be cut along a second direction (for example, a direction perpendicular to the conveying direction) in a manner that can form a cutting surface that intersects with the cutting surface in the first direction.

The cutting knife 100 used for cutting the edge of the optical laminate 10 is a knife having a shape corresponding to the convex parts of the two optical films 11 and 12 of the optical laminate 10. For example, the cutting knife 100 is a corrugated knife. FIG4 shows a part of the tip of the cutting knife 100 as a corrugated knife observed from the direction of pressing toward the longitudinal optical laminate 20. As shown in FIG4, the tip of the cutting knife 100 has a structure in which convex and concave parts corresponding to the convex and concave parts of the two optical films 11 and 12 of the above-mentioned optical laminate 10 are repeated. For example, as shown in FIG4, the repetition pitch P of the cutting knife 100 is 2 mm, and the protruding length L2 of the convex part relative to the concave part is 0.3 mm.

FIG5 schematically shows a cutting knife 100 for cutting a longitudinal optical laminate 20. The longitudinal optical laminate 20 is a laminate of optical films 21, 22 and an adhesive layer 23 that constitute the optical films 11, 12 and the adhesive layer 13 of the optical laminate 10. FIG5 is a diagram observed from the length direction of the cutting knife 100, and the cut edge becomes the depth direction of the drawing. The angle θ2 of the tip of the cutting knife 100 shown in FIG5 can be greater than 40°. In addition, the angle can also be any one of greater than 45°, greater than 50°, and greater than 60°. As shown by the arrow in FIG5, when the longitudinal optical laminate 20 is cut by the cutting knife 100, a lateral (surface direction) stress is applied to the longitudinal optical laminate 20 due to the taper (angle of the tip) of the cutting knife 100.

In the manufacturing method of the present embodiment, the cutting of the longitudinal optical stack 20 by the cutting knife 100 is performed in a state where pressure is applied near the cutting edge of the longitudinal optical stack 20. The pressure applied near the cutting edge of the longitudinal optical stack 20 is performed, for example, by pressing two pressure members 120 at both ends of the cutting knife 100 toward the longitudinal optical stack 20 as shown in FIG5 . The pressure members 120 are, for example, elastic bodies such as sponges. The pressure members 120 are longer (length in the depth direction in FIG5 ) than the cutting knife 100. The cutting of the longitudinal optical stack 20 can be performed in a state where pressure is not applied around the cutting edge of the longitudinal optical stack 20. For example, the cutting of the longitudinal optical stack 20 can be performed in a state where pressure is applied only near the cutting edge of the longitudinal optical stack 20.

The hardness of the elastic body used for pressurization can be 20 to 60, and further 20 to 35, as measured by a rubber hardness meter in accordance with the SRIS-0101 physical testing method of the Rubber Society of Japan standard.

The pressurizing member 120 may be pre-installed on the plate-like member 110 in the same manner as the cutting blade 100. For example, two pressurizing members 120 may be installed on the plate-like member 110 to sandwich the cutting blade 100 for each cutting blade 100. When the cutting blade 100 is pressed against the longitudinal optical laminate 20, the pressurizing member 120 presses both ends of the cutting edge. In addition, the pressurization near the cutting edge may be performed by a method other than pressing with the pressurizing member 120.

The pressurized area may be an area of less than 15 mm on both sides of the cutting edge. Furthermore, the pressurized area may be an area of less than 10 mm on both sides of the cutting edge. In addition, (the lower limit of) the pressurized area may be more than 3 mm on both sides of the cutting edge. Furthermore, (the lower limit of) the pressurized area may be more than 5 mm on both sides of the cutting edge. In addition, the above distance may not be the distance from the cutting edge, but the distance from the long side of the cutting knife 100 (the long side of the tip of the cutting knife 100 shown in FIG. 4 ) in contact with the longitudinal optical laminate 20. The above pressurized area may be an area near the cutting edge, and the surrounding area may be an unpressurized area.

By cutting out each side of the optical layered body 10 from the longitudinally long optical layered body 20 in this manner, (each side surface of) the cut optical layered body 10 has the above-described structure.

In the manufacturing method of the present embodiment, the longitudinal optical stack 20 can be cut while tension is applied in a direction substantially perpendicular to the cutting edge and along the surface direction of the longitudinal optical stack 20. The tension is applied in order to properly cut the adhesive layer 23 with the cutting knife 100 and prevent the cut optical stack 10 from reattaching to the longitudinal optical stack 20 or another optical stack 10. The direction in which the tension is applied is the direction in which the cut longitudinal optical stack 20 is separated from each other. For example, in FIG. 5 , tension is applied in the left-right direction. The tension is applied, for example, by holding both ends of the longitudinal optical stack 20 in the direction in which the tension is applied and pulling one or both of the held portions. In addition, the tension may be applied by any conventional method other than this.

The force applied to the longitudinal optical laminate 20 for properly cutting the adhesive layer 23 and preventing the cut optical laminate 10 from reattaching can be implemented by a pressurizing member 120 (for example, the above-mentioned elastic body) for pressurizing the vicinity of the cut edge of the longitudinal optical laminate 20. For example, in order to achieve the above, as shown in (a) to (d) of FIG. 6, the shape of the pressurizing member 120 is made to be farther away from the base of the cutting knife 100. In addition, similar to FIG. 5, FIG. 6 is a view observed from the longitudinal direction of the cutting knife 100.

For example, as shown in FIG6(a), the surface of the pressurizing member 120 on the cutting blade 100 side may be inclined so as to move away from the cutting blade 100 as it moves toward the tip of the cutting blade 100. Also, as shown in FIG6(b), the corner of the tip of the pressurizing member 120 on the cutting blade 100 side may be C-chamfered. Also, as shown in FIG6(c), the corner of the tip of the pressurizing member 120 on the cutting blade 100 side may be R-chamfered. Also, in addition to the shape of the pressurizing member 120 on the cutting blade 100 side, the surface of the pressurizing member 120 on the side opposite to the cutting blade 100 may be inclined so as to move away from the cutting blade 100 as it moves toward the tip of the cutting blade 100, as shown in FIG6(d).

By making the pressurizing member 120 into the above-mentioned shape, as shown in FIG6(e), when the pressurizing member 120 is pressed against the longitudinal optical laminate 20 when the longitudinal optical laminate 20 is cut by the cutting blade 100, the pressurizing member 120 is deformed so as to be away from the cutting blade 100. Due to this deformation, a force from the cut edge toward the outside is applied to the longitudinal optical laminate 20 from the pressurizing member 120. Thus, the adhesive layer 23 can be appropriately cut and the cut optical laminate 10 can be prevented from being attached again.

In order to perform appropriate cutting, the angle of the surface of the pressurizing member 120 on the cutting knife 100 side shown in FIG. 6 (d) and the like, which moves away from the cutting knife 100 as it moves toward the tip of the cutting knife 100 (the angle between a straight line going directly downward from the tip of the knife and the surface of the pressurizing member 120) may be 0° to 30°. Alternatively, in order to perform appropriate cutting, the angle may be further 5° to 20°. In the case of using a sponge as the pressurizing member 120, if the angle exceeds 30°, the force of the pressurizing member 120 to pressurize the longitudinal optical laminate 20 becomes weak.

The numerical values of the method for producing the optical layered body 10 described above are numerical values for appropriately producing the optical layered body 10. The above is the method for producing the optical layered body 10 of the present embodiment.

In the optical laminate 10 of the present embodiment, since the side surface of the adhesive layer 13 is located at a position inside the top of the convex portion of the optical film 11, 12, it is possible to appropriately prevent the adhesive from overflowing from the optical laminate 10. Therefore, the optical laminate 10 of the present embodiment has excellent processability and transportability. For example, when manufacturing the optical laminate 10, the optical laminate 10 can be easily separated one by one. In addition, it is possible to prevent adhesion and adhesive contamination with respect to the conveyor belt guide during transportation. In addition, the sticky feeling during the handling of the optical laminate 10 can be eliminated.

In order to make the processability and conveyability of the optical layered body 10 more excellent, the optical layered body 10 may have the following structure as in the above-mentioned embodiment.

A recessed portion may be provided adjacent to the convex portion of the side surface of the two optical films 11 and 12. In addition, the convex portion and the recessed portion may be provided continuously in the optical films 11 and 12. That is, the side surface of the optical films 11 and 12 may be in a wave shape in which the convex portion and the recessed portion are continuous. However, the two optical films 11 and 12 of the optical laminate 10 may also be provided with at least one convex portion.

The convex angle formed by the lines connecting the top of the convex portion and the two ends of the convex portion in the optical films 11 and 12 can be 170 to 120 degrees, and the convex protrusion length, which is the length of the convex protrusion, can be 0.1 to 0.5 mm. However, the convex angle and the convex protrusion length may not be within the above ranges.

The maximum difference between the tip of the convex portion and the side surface of the pressure-sensitive adhesive layer in the protruding direction of the convex portion of the optical films 11 and 12 may be 20 to 100 μm. However, the maximum difference may not be within the above range.

Moreover, according to the manufacturing method of the optical layered body 10 of this embodiment, the optical layered body 10 of this embodiment can be manufactured.

In order to appropriately and reliably manufacture the optical layered body 10 , the method for manufacturing the optical layered body 10 may have the following configuration as in the above-mentioned embodiment.

The longitudinal optical stack 20 can be cut while tension is applied in a direction substantially perpendicular to the cutting edge and along the surface direction of the longitudinal optical stack 20. According to this structure, the cutting edge is easily cut when the longitudinal optical stack 20 is cut, and the optical stack 10 can be more appropriately separated from the longitudinal optical stack 20. However, it is not necessarily necessary to apply tension when cutting.

The angle of the blade tip of the cutting knife 100 may be 40° or more. According to this structure, the longitudinal optical laminate 20 can be appropriately and reliably cut. However, the angle of the blade tip of the cutting knife 100 may not be within the above range.

The longitudinal optical stack 20 is cut along the first direction by two substantially parallel cutting knives 100, and after cutting along the first direction, it is cut along the second direction so as to form a cutting surface intersecting with the cutting surface in the first direction. According to this structure, the optical stack 10 can be appropriately and reliably cut out from the longitudinal optical stack 20. However, it is not necessarily necessary to cut with the cutting knife 100 as described above.

Next, the examples and comparative examples of the present embodiment are described. In the examples and comparative examples, a cutting knife is used to cut a longitudinal optical stack into a plurality of roughly rectangular single-sheet optical stacks. Next, a pen having a cushioning rubber and a double-sided tape attached to the top is adhered to the main surface of the cut single-sheet optical stack, and the single-sheet optical stack is lifted in a vertical direction and moved to another place. At this time, the following situation is confirmed: whether the moved single-sheet optical stack can move in a state of being separated from each other without being combined with the adjacent single-sheet optical stack.

The maximum difference between the top of the convex portion and the side surface of the adhesive layer in the protruding direction of the convex portion of the optical film in the single-sheet optical laminate, that is, the depression amount of the adhesive layer was measured using a microscope (VHX-5000, manufactured by KEYENCE Corporation).

The storage modulus of the adhesive layer was measured at 23°C and 80°C using a dynamic viscoelasticity measuring apparatus (Dynamic Analyzer RDA II: manufactured by REOMETRIC Corporation) using a cylindrical piece with a diameter of 8 mm and a thickness of 1 mm as a test piece by a torsional shear method with a frequency of 1 Hz.

First, a longitudinal optical laminate was prepared as follows: 3 parts of carboxyl-modified polyvinyl alcohol [KL-318 manufactured by Kuraray Co., Ltd.] were dissolved in 100 parts of water, and 1.5 parts of a polyamide epoxy additive as a water-soluble epoxy compound [Sumirez Resin 650 (30) manufactured by Sumika Chemtex Co., Ltd., an aqueous solution having a solid content concentration of 30%] were added to the aqueous solution to prepare a water-based adhesive (water-soluble adhesive).

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

On one side of the prepared polarizer, a transparent protective film composed of triacetyl cellulose [KC2UA made by Konica Minolta (Co., Ltd.), thickness 25 μm] was laminated using the above-mentioned water-based adhesive, and on the other side, a transparent protective film composed of cycloolefin polymer [trade name "ZF14" made by Japan ZEON (Co., Ltd.), thickness 23 μm] was laminated using the above-mentioned water-based adhesive, and then dried at 80° C. for 5 minutes, thereby obtaining a polarizing plate. In addition, before lamination, the transparent protective film composed of triacetyl cellulose was subjected to saponification treatment, and the bonding surface between the transparent protective film composed of cycloolefin polymer and the polarizer was subjected to corona treatment.

Next, a commercially available adhesive is prepared. The commercially available adhesive is an adhesive having a 220 μm adhesive layer formed on the release-treated surface of a release-treated protective film having a thickness of 100 μm. The adhesive layer is an adhesive layer sandwiched between two optical films in the manufactured longitudinal optical laminate. The protective film is an optical film sandwiching an adhesive layer together with the polarizing plate in the manufactured longitudinal optical laminate.

A longitudinal optical laminate is prepared by laminating an adhesive layer with a protective film on the transparent protective film surface of the prepared polarizing plate made of triacetyl cellulose. The prepared longitudinal optical laminate becomes a laminate of polarizing plate/adhesive layer/protective film (corresponding to optical film 11/adhesive layer 13/optical film 12 in FIG. 1 , respectively).

The commercially available adhesive had a storage elastic modulus of 0.06 MPa at 25° C. and a tan δ (loss tangent) of 0.36 at 70° C. In this manner, a longitudinal optical layered body having a width of 600 mm and a length of 100 m was produced.

In the examples and comparative examples, the following knife dies were prepared as cutting knives for cutting out individual optical layered bodies from the longitudinal optical layered body.

Knife die A: A knife die was prepared in which four knives (NCEW07 manufactured by Nakayama Co., Ltd., product code 338216) with a repeated structure of wave-shaped concave and convex were arranged in parallel at intervals of 153 mm. As a structure for pressurizing the longitudinal optical laminate, sponges with a rectangular cross-section and a sponge hardness of 35 (the hardness is measured by a rubber hardness meter according to the SRIS-0101 physical test method of the Japanese Rubber Association standard specification, and the same applies below) and a sponge width of 7 mm were arranged at both ends of the knife. In addition, the sponge was set in a manner that protruded 1.4 mm from the top of the knife.

Knife die B: A knife die was prepared in which eight knives having a repeated structure of wave-shaped concave and convex (NCEW07 manufactured by Nakayama Co., Ltd., product code 338216) were arranged in parallel at intervals of 168 mm. As a structure for pressurizing the longitudinal optical laminate, sponges with a rectangular cross-section, a sponge hardness of 35, and a sponge width of 7 mm were arranged at both ends of the knife. In addition, the sponge was arranged so as to protrude 1.4 mm from the tip of the knife.

Knife die C: A knife die was prepared in which four knives (NCEW07 manufactured by Nakayama Co., Ltd., product code 338216) having a repeated structure of wave-shaped projections and depressions were arranged in parallel at intervals of 153 mm. As a structure for pressurizing the longitudinal optical laminate, a sponge with a sponge hardness of 35 and a sponge width of 7 mm, whose cross section was inclined outward toward the tip of the knife as shown in (d) of Figure 6, was arranged at both ends of the knife. In addition, the sponge was arranged in a manner protruding 1.4 mm from the top of the knife. The angle formed by the straight line from the tip of the knife toward the downward direction and the straight line of the cross section of the sponge inclined outward toward the tip of the knife was 10°.

Knife die D: A knife die was prepared in which eight knives (NCEW07 manufactured by Nakayama Co., Ltd., product code 338216) having a repeated structure of wave-shaped projections and depressions were arranged in parallel at intervals of 168 mm. As a structure for pressurizing the longitudinal optical laminate, a sponge with a sponge hardness of 35 and a sponge width of 7 mm, whose cross section was inclined outward toward the knife tip as shown in (d) of Figure 6, was arranged at both ends of the knife. In addition, the sponge was arranged in a manner protruding 1.4 mm from the top of the knife. The angle formed by the straight line from the knife tip toward the downward direction and the straight line of the cross section of the sponge inclined outward toward the knife tip was 10°.

Knife die E: A knife die was prepared in which four knives (NCEW07, product code 338216, manufactured by Nakayama Co., Ltd.) having a repeated structure of wave-shaped concave and convex were arranged in parallel at intervals of 153 mm. As a structure for pressurizing the longitudinal optical laminate, a sponge with a rectangular cross section and a sponge hardness of 35 was arranged without gaps in the area without the knife. In addition, the sponge was arranged so as to protrude 1.4 mm from the tip of the knife.

Knife die F: A knife die was prepared in which eight knives (NCEW07, product code 338216, manufactured by Nakayama Co., Ltd.) having a repeated structure of wave-shaped concave and convex were arranged in parallel at intervals of 168 mm. As a structure for pressurizing the longitudinal optical laminate, a sponge with a rectangular cross section and a sponge hardness of 35 was arranged without gaps in the area without the knives. In addition, the sponge was arranged so as to protrude 1.4 mm from the tip of the knife.

Knife die G: A knife die was prepared in which four knives having a repeated structure of wave-like concave and convex shapes (NCEW07 manufactured by Nakayama Co., Ltd., product code 338216) were arranged in parallel at intervals of 168 mm.

Knife die H: A knife die was prepared in which eight knives having a repeated structure of wave-like concave and convex shapes (NCEW07 manufactured by Nakayama Co., Ltd., product code 338216) were arranged in parallel at intervals of 168 mm.

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

As Example 1, while the manufactured longitudinal optical stack is being conveyed and stopped, the longitudinal optical stack is cut using knife die A. For the knife of knife die A, a knife arranged in parallel with the conveying direction of the longitudinal optical stack is used. Next, the longitudinal optical stack is cut using knife die B. For the knife of knife die B, a knife arranged in perpendicular to the conveying direction of the longitudinal optical stack is used. The optical stack cut in this way is a roughly rectangular optical stack of 153 mm × 168 mm, and 21 optical stacks can be obtained. All the optical stacks after cutting are not attached to adjacent optical stacks, and the separability of the manufactured optical stack is good. The depression amount of the adhesive layer in the direction of the protruding convex part of the optical film is 20 to 50 μm.

As Example 2, while the manufactured longitudinal optical stack is being conveyed and stopped, the longitudinal optical stack is cut using a knife die C. For the knife of the knife die C, a knife arranged in parallel with the conveying direction of the longitudinal optical stack is used. Next, the longitudinal optical stack is cut using a knife die D. For the knife of the knife die D, a knife arranged in perpendicular to the conveying direction of the longitudinal optical stack is used. The optical stack cut in this way is a roughly rectangular optical stack of 153 mm × 168 mm, and 21 optical stacks can be obtained. All the optical stacks after cutting are not attached to adjacent optical stacks, and the separability of the manufactured optical stack is better. The depression amount of the adhesive layer in the direction of the protrusion of the convex part of the optical film is 60 to 100 μm.

As Comparative Example 1, while the manufactured longitudinal optical laminate is being conveyed and stopped, the longitudinal optical laminate is cut using die cutter E. For the blade of die cutter E, a blade arranged in parallel with the conveying direction of the longitudinal optical laminate is used. Next, the longitudinal optical laminate is cut using die cutter F. For the blade of die cutter F, a blade arranged in perpendicular to the conveying direction of the longitudinal optical laminate is used. The optical laminate cut in this way is a roughly rectangular optical laminate of 153 mm × 168 mm, and 21 optical laminates can be obtained. After cutting, all the optical laminates are attached to the adjacent optical laminates again and connected together, and the separability of the manufactured optical laminate is not good. No depression of the adhesive layer in the direction of the protruding convex portion of the optical film is confirmed. As described above, since a plurality of optical laminates are connected together, it can be considered that the adhesive layer of the convex portion is flush or protruding.

As Comparative Example 2, while the manufactured longitudinal optical stack is being conveyed and stopped, the longitudinal optical stack is cut using a knife die G. For the knife of the knife die G, a knife arranged in parallel with the conveying direction of the longitudinal optical stack is used. Next, the longitudinal optical stack is cut using a knife die H. For the knife of the knife die H, a knife arranged in perpendicular to the conveying direction of the longitudinal optical stack is used. The optical stack cut in this way is not separated from the knife die after cutting, so the roughly rectangular optical stack of 153 mm × 168 mm cannot be recovered.

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

[1] A manufacturing method, which is a manufacturing method for 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, and convex portions protruding in the surface direction of the optical films are provided on the side surfaces of the two optical films, the convex portions on the side surfaces of the two optical films are located at positions opposite to each other, and a portion of the side surface of the adhesive layer at a position corresponding to the position of the top of the convex portion is located at a position inner than the position of the top of the convex portion, the adhesive constituting the adhesive layer has a tan δ of 0.30 to 0.80 at 70°C, and a storage modulus of 0.05 to 0.40 MPa at 25°C, and a thickness of the adhesive layer is 50 μm or more, and the longitudinal optical laminate comprising the two optical films and the adhesive layer sandwiched by the two optical films is cut along the stacking direction of the longitudinal optical laminate using a knife having a shape corresponding to the convex portion while applying pressure near the cutting edge thereof.

[2] The manufacturing method according to [1], wherein the longitudinal optical layered body is cut while tension is applied in a direction substantially perpendicular to the cutting edge and along the surface direction of the longitudinal optical layered body.

[3] The manufacturing method according to [1] or [2], wherein the angle of the blade tip of the knife is greater than 40°.

[4] A manufacturing method according to any one of [1] to [3], wherein the longitudinal optical layered body is cut along a first direction using two substantially parallel knives, and after cutting in the first direction, it is cut along a second direction in a manner capable of forming a cutting surface that intersects with the cutting surface in the first direction.

[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, and the sides of the two optical films are provided with convex portions protruding in the surface direction of the optical films, the convex portions on the sides of the two optical films are located relative to each other, and a portion of the side of the adhesive layer at a position corresponding to the position of the top of the convex portion is located more inner than the position of the top of the convex portion, the adhesive constituting the adhesive layer has a tanδ of 0.30 to 0.80 at 70°C, and a storage modulus of 0.05 to 0.40 MPa at 25°C, and the thickness of the adhesive layer is 50 μm or more.

[6] The optical layered body according to [5], wherein a recessed portion is provided adjacent to the raised portion on the side surfaces of the two optical films.

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

[8] An optical laminate according to any one of [5] to [7], wherein the convex angle formed by the lines connecting the top of the convex portion and the two ends of the convex portion is 170 to 120°, and the convex protrusion length, which is the length of the convex protrusion, is 0.1 to 0.5 mm.

[9] The optical layered body according to any one of [5] to [8], wherein the maximum difference between the tip of the convex portion and the side surface of the pressure-sensitive adhesive layer in the protruding direction of the convex portion is 20 to 100 μm.

Claims (9)

1. A method for producing an optical layered body, comprising: The optical laminate includes two optical films and a pressure-sensitive adhesive layer sandwiched between 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 portions protruding toward the surface direction of the optical films, and the convex portions on the side surfaces of the two optical films are located at positions facing each other. The portion of the side surface of the adhesive layer at a position corresponding to the position of the top end of the convex portion is located inside the position of the top end of the convex portion. The adhesive constituting the adhesive layer has a tan δ of 0.30 to 0.80 at 70°C and a storage modulus of 0.05 to 0.40 MPa at 25°C. The thickness of the adhesive layer is 50 μm or more, The long optical layered body including two optical films and a pressure-sensitive adhesive layer sandwiched between the two optical films is pressurized near the cut edge, and the long optical layered body is cut along the laminating direction of the long optical layered body using a knife having a shape corresponding to the convex portion. 2. The manufacturing method according to claim 1, wherein: The longitudinal optical layered body is cut while tension is applied in a direction substantially perpendicular to the cutting side and along the surface direction of the longitudinal optical layered body. 3. The manufacturing method according to claim 1 or 2, wherein: The angle of the knife tip is greater than 40°. 4. The manufacturing method according to claim 1 or 2, wherein: The longitudinal optical layered body is cut in a first direction by two substantially parallel knives, and after the cutting in the first direction, it is cut in a second direction so as to form a cut surface intersecting with the cut surface in the first direction. 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, The side surfaces of the two optical films are provided with convex portions protruding toward the surface direction of the optical films, and the convex portions on the side surfaces of the two optical films are located at positions facing each other. The portion of the side surface of the adhesive layer at a position corresponding to the position of the top end of the convex portion is located inside the position of the top end of the convex portion. The adhesive constituting the adhesive layer has a tan δ of 0.30 to 0.80 at 70°C and a storage modulus of 0.05 to 0.40 MPa at 25°C. The adhesive layer has a thickness of 50 μm or more. 6. The optical layered body according to claim 5, wherein: A concave portion is provided adjacent to the convex portion on the side surfaces of the two optical films. 7. The optical layered body according to claim 6, wherein: The convex portion and the concave portion are provided continuously. 8. The optical layered body according to any one of claims 5 to 7, wherein The convex angle formed by each line connecting the tip of the convex portion and both ends of the convex portion is 170 to 120 degrees, and the convex protrusion length, which is the length of the convex portion protruding, is 0.1 to 0.5 mm. 9. The optical layered body 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 protruding direction of the convex portion is 20 to 100 μm.