JP7578422B2 - Optical laminate - Google Patents

Description

The present invention relates to an optical laminate including a polarizing plate.

Polarizing plates are widely used as polarized light supplying elements and polarized light detecting elements in display devices such as liquid crystal display devices and organic electroluminescence (EL) display devices. Conventionally, polarizing plates have been used in which a protective film is adhered to one or both sides of a polarizer.

Display devices equipped with polarizing plates are also being used in mobile devices such as notebook personal computers and mobile phones, and polarizing plates with areas of different transmittance are required due to the need for diversifying display purposes, clarifying display classifications, and decorative applications. In particular, in small and medium-sized mobile terminals such as smartphones and tablet terminals, a polarizing plate is sometimes attached to the entire surface to create a seamless design from the perspective of decorativeness. In this case, the polarizing plate overlaps the area of the camera lens and the area where icons and logos are printed at the bottom of the screen, which can cause problems such as poor camera sensitivity and poor design.

For this reason, it is known to perform processing such as forming holes in the polarizing plate to prevent a decrease in the sensitivity and design of the camera, and to perform chemical processing on the polarizer contained in the polarizing plate to form a non-polarized part so as not to adversely affect the camera performance (for example, Patent Documents 1 to 3).

JP 2017-194568 A JP 2018-28563 A JP 2018-31954 A

A polarizing plate having holes is attached to a member constituting a display device via an attachment layer such as a pressure sensitive adhesive layer or an adhesive layer. When attaching a polarizing plate having holes to the above-mentioned member, problems such as air bubbles being generated around the hollow hole or foreign matter being mixed into the hollow may occur.

The present invention aims to provide an optical laminate that can suppress defects such as the generation of air bubbles and the inclusion of foreign matter when laminating a polarizing plate to another member.

The present invention provides the following optical laminate.
[1] A polarizing plate including a polarizing layer and a protective layer provided on one or both sides of the polarizing layer, the polarizing layer having a hole penetrating the polarizing layer and the protective layer in a lamination direction,
The hole is filled with a light-transmitting filler.
[2] The optical laminate according to [1], wherein the filler is provided in the entire hole.
[3] The optical laminate according to [1] or [2], wherein the filler contains a resin.
[4] The optical laminate according to any one of [1] to [3], wherein the polarizing plate has a thickness of 15 μm or more.
[5] The optical laminate according to any one of [1] to [4], wherein the hole has a diameter of 0.5 mm or more and 20 mm or less.
[6] The optical laminate according to any one of [1] to [5], further comprising a first pressure-sensitive adhesive layer on one surface side of the polarizing plate.
[7] The optical laminate according to [6], further comprising a first release film on the side of the first pressure-sensitive adhesive layer opposite the polarizing plate.
[8] The optical laminate according to [6], further comprising an image display element layer on the side of the first pressure-sensitive adhesive layer opposite to the polarizing plate.
[9] The optical laminate according to any one of [6] to [8], further comprising a first functional layer between the polarizing plate and the first pressure-sensitive adhesive layer.
[10] The optical laminate according to [9], wherein the first functional layer includes at least one of an optical film and a touch sensor panel.
[11] The optical laminate according to any one of [6] to [10], further comprising a second pressure-sensitive adhesive layer on the other surface of the polarizing plate.
[12] The optical laminate according to [11], wherein the filler is the same adhesive as the adhesive constituting the second adhesive layer.
[13] The optical laminate according to [11] or [12], further comprising a second release film on the side of the second pressure-sensitive adhesive layer opposite the polarizing plate.
[14] The optical laminate according to [11] or [12], further comprising a second functional layer on the side of the second pressure-sensitive adhesive layer opposite the polarizing plate.
[15] The optical laminate according to [14], wherein the second functional layer includes at least one of a touch sensor panel and a cover member.

In this specification, the layer (first release film or image display element layer) provided on "the surface of the first pressure-sensitive adhesive layer opposite the polarizing plate" may or may not be in direct contact with the first pressure-sensitive adhesive layer. The same applies to the layer (second release film or second functional layer) provided on "the surface of the second pressure-sensitive adhesive layer opposite the polarizing plate".
In this specification, a layer provided "on a surface" refers to a layer that is in contact with the surface.

According to the present invention, it is possible to provide an optical laminate that is less susceptible to the generation of air bubbles and the inclusion of foreign matter, even if the laminate has a structure in which a polarizing plate having holes is laminated to another member.

FIG. 1 is a schematic plan view illustrating an example of an optical laminate of the present invention. This is an x-x' cross-sectional view of the optical laminate shown in Figure 1. FIG. 2 is a schematic cross-sectional view showing another example of the optical laminate of the present invention. FIG. 2 is a schematic cross-sectional view showing a further example of the optical laminate of the present invention. FIG. 2 is a schematic cross-sectional view showing a further example of the optical laminate of the present invention. 3A and 3B are schematic cross-sectional views showing still another example of the optical laminate of the present invention. FIG. 2 is a schematic cross-sectional view showing a further example of the optical laminate of the present invention.

Below, preferred embodiments of the optical laminate of the present invention will be described with reference to the drawings. In all of the drawings below, the scale of each component has been appropriately adjusted to make it easier to understand, and the scale of each component shown in the drawings does not necessarily match the scale of the actual component.

(Optical laminate)
Fig. 1 is a schematic plan view showing an example of the optical laminate of the present invention, and Fig. 2 is a cross-sectional view taken along line xx' of the optical laminate shown in Fig. 1.
The optical laminate 1 shown in FIG. 1 and FIG.
The polarizing plate 10 is formed by laminating a polarizing layer 11 and a protective layer 12 provided on one or both sides of the polarizing layer 11, and has a hole 15 penetrating the polarizing layer 11 and the protective layer 12 in the lamination direction.
The hole 15 is filled with a light-transmitting filling material.

In the optical laminate 1, the polarizing layer 11 is not present in the hole 15 of the polarizing plate 10, and the area where this hole 15 is located can be made into a non-polarized area. Therefore, when the optical laminate 1 is applied to a display device such as a liquid crystal display device or an organic EL display device deployed in a smartphone or tablet type terminal, a camera lens or a printed part such as an icon or logo can be placed in the area where the hole 15 is located, thereby preventing a decrease in camera sensitivity and a decrease in design.

In the optical laminate 1, the hole 15 of the polarizing plate 10 is filled with the filler 20, so that the hole 15 can be made solid and no voids are present. This makes it possible to prevent foreign matter from entering the hole 15 of the polarizing plate 10.
In addition, as described later, when an adhesive sheet or a functional layer (such as a cover member, a touch sensor panel, or an optical film, which will be described later) having an adhesive layer formed on a release film is laminated on the surface of the polarizing plate 10 on which the other side of the hole 15 is located, with one side of the hole 15 of the polarizing plate 10 blocked, it is possible to suppress the intrusion of foreign matter into the hole 15 or the intrusion of air bubbles around the hole 15. If the hole 15 is not filled with the filler 20, it is necessary to perform the lamination while also performing a heat treatment in a vacuum booth as necessary in order to suppress the intrusion of foreign matter or air bubbles. In contrast, by filling the hole 15 with the filler 20 as in this embodiment, the intrusion of foreign matter or air bubbles is easily suppressed even if the lamination is not performed under vacuum conditions or vacuum heating conditions.

The planar shape of the optical laminate 1 is not particularly limited, but is usually a quadrangle as shown in Fig. 1. The quadrangle constituting the optical laminate 1 may be a rectangle or a square, and at least one of the four corners may be rounded (a shape having an R).
1 is a sheet-like body, but may be a long body. The optical laminate 1 may be cut into a predetermined shape as necessary.

The optical laminate 1 may have a protective film on one or both sides. The protective film is provided to prevent scratches, stains, and the like from occurring on the surface of the polarizing plate 10 during the production of a product using the optical laminate 1, or during the production and transportation of the optical laminate 1. The protective film is provided on the polarizing plate 10 in a peelable manner.
The protective film may be a base film having an adhesive layer thereon, or may be a self-adhesive film.
The resin used for the base film of the protective film may be the resin used for the protective layer described below, and the adhesive layer may be the adhesive described below. The self-adhesive film may be formed using, for example, a polypropylene-based resin, a polyethylene-based resin, or the like.

(Polarizing plate)
As shown in FIG. 2, the polarizing plate 10 has a polarizing layer 11, and a first protective layer 12a and a second protective layer 12b provided on both sides of the polarizing layer 11, respectively.
The first protective layer 12a and the second protective layer 12b may be provided on the polarizing layer 11 via an attachment layer such as a pressure-sensitive adhesive layer or an adhesive layer, or may be provided directly on the polarizing layer 11 without an attachment layer.
The polarizing plate 10 may include only one of the first protective layer 12a and the second protective layer 12b shown in FIG.

As described above, the polarizing plate 10 has the hole 15 penetrating the polarizing layer 11, the first protective layer 12a, and the second protective layer 12b in the stacking direction. That is, the polarizing layer 11, the first protective layer 12a, and the second protective layer 12b each have a hole penetrating in their thickness direction.
The planar shape of the hole 15 is not particularly limited, but may be a circle; an ellipse; an oval; a polygon such as a triangle or a rectangle; a rounded polygon having at least one corner rounded (a shape having an R), or the like.

The diameter of the hole 15 is preferably 0.5 mm or more, may be 1 mm or more, may be 2 mm or more, or may be 3 mm or more. The diameter of the hole 15 is preferably 20 mm or less, may be 15 mm or less, may be 10 mm or less, or may be 7 mm or less.
In this specification, the diameter of a hole refers to the diameter of a circle when the shape of the hole in plan view is circular (perfect circle), and refers to the diameter of the circumscribing circle (perfect circle) of the hole in plan view when the shape of the hole in plan view is other than circular (perfect circle).

The thickness of the polarizing plate 10 is preferably 15 μm or more, more preferably 30 μm or more, and may be 50 μm or more, 60 μm or more, or 80 μm or more. The thickness of the polarizing plate 10 is usually 300 μm or less, and may be 250 μm or less, 200 μm or less, or 150 μm or less.

The holes 15 in the polarizing plate 10 can be formed by punching, cutting, machining, laser cutting, etc.

The polarizing plate 10 may have one hole 15 or may have two or more holes 15. When the polarizing plate 10 has two or more holes 15, the shapes and diameters of the holes 15 may be the same as each other or may be different from each other.

(Polarizing Layer)
The polarizing layer 11 is a linear polarizer that has the property of transmitting linearly polarized light having a vibration plane perpendicular to the absorption axis when unpolarized light is incident on the polarizing layer 11 .
The polarizing layer 11 may be, for example, a polyvinyl alcohol (hereinafter, sometimes referred to as "PVA") film that has been subjected to a dyeing process using a dichroic substance such as iodine or a dichroic dye, a stretching process, a crosslinking process, and the like.
The polarizing layer 11 may be a cured film obtained by aligning a dichroic dye in a polymerizable liquid crystal compound and polymerizing the polymerizable liquid crystal compound. Such a polarizing layer 11 can be obtained, for example, by applying a polarizer-forming composition containing a polymerizable liquid crystal compound and a dichroic dye onto a substrate film, and polymerizing and curing the polymerizable liquid crystal compound while maintaining the liquid crystal state.

The thickness of the polarizing layer 11 can be 40 μm or less, and is preferably 30 μm or less (e.g., 20 μm or less, further 15 μm or less, or even 10 μm or less or 8 μm or less). The thickness of the polarizing layer 11 is usually 2 μm or more, and may be 5 μm or more.

(Protective Layer)
The protective layer 12 (first protective layer 12a, second protective layer 12b) provided on one or both sides of the polarizing layer 11 is not limited as long as it is a resin layer that can transmit light, and may be a resin film or a coating layer formed by applying a composition containing a resin.

The resin used in the resin layer is preferably a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, stretchability, etc. Examples of such thermoplastic resins include cellulose-based resins such as triacetyl cellulose; polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate; polyethersulfone-based resins; polysulfone-based resins; polycarbonate-based resins; polyamide-based resins such as nylon and aromatic polyamide; polyimide-based resins; polyolefin-based resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; cyclic polyolefin-based resins having cyclo- and norbornene structures; (meth)acrylic-based resins; polyarylate-based resins; polystyrene-based resins; polyvinyl alcohol-based resins, and mixtures thereof.
When the protective layers 12 are laminated on both sides of the polarizing layer 11, the resin compositions of the protective layers 12 may be the same as or different from each other.

When the protective layer 12 is a resin film, the protective layer 12 can be provided on the polarizing layer 11 via an attachment layer. The pressure-sensitive adhesive and adhesive constituting the attachment layer can be the pressure-sensitive adhesive and adhesive described below.
When the protective layer 12 is a coating layer, it can be formed by coating the polarizing layer 11 with a composition containing the above-mentioned resin.

From the viewpoint of thinning, the thickness of the protective layer 12 is usually 200 μm or less, preferably 150 μm or less, more preferably 100 μm or less, and may be 80 μm or less, or may be 60 μm or less. The thickness of the protective layer 12 is usually 5 μm or more, may be 10 μm or more, or may be 20 μm or more. The protective layer 12 may or may not have a phase difference.
When the protective layers 12 are laminated on both sides of the polarizing layer 11, the protective layers 12 may have the same thickness or different thicknesses.

(Filling material)
The holes 15 of the polarizing plate 10 are filled with a filler 20. The filler 20 is usually provided so as to fill the entire holes 15.
The filler 20 has translucency. In this specification, translucency refers to a property that transmits 80% or more of visible light in the wavelength range of 400 nm to 700 nm. The translucency of the filler 20 may be such that 85% or more of visible light in the above wavelength range is transmitted, or 90% or more of the visible light is transmitted, or 95% or more of the visible light is transmitted.

There are no particular limitations on the filler 20 as long as it has light-transmitting properties and can fill the holes 15 in the polarizing plate 10, but it is preferable that the filler contains a resin.
The resin may be, for example, one or more selected from the group consisting of pressure sensitive adhesives, adhesives, and thermoplastic resins.

A pressure-sensitive adhesive exhibits adhesive properties when it is attached to an adherend, and is known as a pressure-sensitive adhesive.
Examples of the adhesive include those containing a polymer such as a (meth)acrylic polymer, a silicone polymer, a polyester polymer, a polyurethane polymer, a polyether polymer, or a rubber polymer as a main component. In this specification, the main component refers to a component that contains 50 mass% or more of the total solid content of the adhesive. The adhesive may be an active energy ray curable type or a heat curable type, and the degree of crosslinking or adhesive strength may be adjusted by irradiation with active energy rays or heating.
In this specification, "(meth)acrylic" means either acrylic or methacrylic.

The adhesive is preferably a (meth)acrylic adhesive from the viewpoints of transparency, adhesive strength, reliability, weather resistance, heat resistance, etc. For the (meth)acrylic adhesive, a (meth)acrylic polymer having a weight average molecular weight of 100,000 or more as the main component is useful, which is a mixture of a (meth)acrylic acid alkyl ester having an alkyl group with 20 or less carbon atoms, such as a methyl group, an ethyl group, or a n-, i-, or t-butyl group, and a functional group-containing (meth)acrylic monomer, such as (meth)acrylic acid or hydroxyethyl (meth)acrylate, so that the glass transition temperature is preferably 25°C or less, more preferably 0°C or less.

The adhesive is an adhesive that contains a curable resin component (so-called curable resin) and is an adhesive other than a pressure-sensitive adhesive (adhesive).
Examples of the adhesive include water-based adhesives in which a curable resin component is dissolved or dispersed in water, active energy ray-curable adhesives containing an active energy ray-curable compound, and thermosetting adhesives.

Examples of the resin component contained in the water-based adhesive include polyvinyl alcohol-based resins and urethane-based resins.
Examples of the active energy ray-curable adhesive include compositions that are cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, X-rays, etc. The composition that is cured by irradiation with active energy rays is preferably an ultraviolet ray-curable composition, and more preferably contains an epoxy-based compound that is cured by cationic polymerization as a curable component.
Examples of the thermosetting adhesive include those containing an epoxy resin, a silicone resin, a phenol resin, a melamine resin, or the like as a main component.

Examples of thermoplastic resins include polyolefin resins such as linear polyolefin resins (polypropylene resins, etc.) and cyclic polyolefin resins (norbornene resins, etc.); cellulose ester resins such as triacetyl cellulose and diacetyl cellulose; polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate resins; (meth)acrylic resins; and polystyrene resins. The thermoplastic resin may be, for example, a filament-like thermoplastic resin used in a 3D printer or the like.

The above-mentioned adhesive, adhesive, or thermoplastic resin can be injected into hole 15 of polarizing plate 10 in a fluid state such as liquid, particulate, or powder, and then, as necessary, dried or hardened if in liquid form after injection, or melted and solidified if in particulate or powder form, thereby filling hole 15 with filler 20.
Alternatively, the pressure-sensitive adhesive, adhesive, or thermoplastic resin may be molded in advance to match the shape of the hole 15, and the molded product may be fitted into the hole 15 of the polarizing plate 10 to fill the filler 20. In this case, it is preferable to form the molded product to have the same size as the shape of the hole 15, or to have a size that is more than 0 mm and not more than 0.2 mm smaller than the size of the hole 15.

(Another example of the optical laminate [1])
FIG. 3 is a schematic cross-sectional view showing another example of the optical laminate of the present invention.
The optical laminate 2 shown in FIG. 3 further includes a first pressure-sensitive adhesive layer 31 and a first release film 32 in this order on one surface side of the optical laminate 1 shown in FIG.
The first adhesive layer 31 may be provided on the second protective layer 12b of the polarizing plate 10 as shown in FIG. 3, or may be provided on the first protective layer 12a.
When the polarizing plate 10 has the protective layer 12 on only one side, the first pressure-sensitive adhesive layer 31 and the first release film 32 can be provided in this order on the protective layer 12 or on the polarizing layer 11 .
The first adhesive layer 31 may be provided so as to be in direct contact with the polarizing plate 10 as shown in FIG. 3, or may be provided so as to be in direct contact with a first functional layer (optical film, touch sensor panel, etc.) provided as a protective layer for the polarizing plate 10 as described below.

The first pressure-sensitive adhesive layer 31 can be used as an attachment layer for attaching to an image display element layer described later.
The first pressure-sensitive adhesive layer 31 may have a hole penetrating in the stacking direction of the layers in a region where the hole 15 of the polarizing plate 10 is located. In this case, in the optical laminate 2, the hole of the first pressure-sensitive adhesive layer 31 is preferably filled with a filler 20. In the optical laminate 2, the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 31 may be used as the filler 20 that fills the hole 15 of the polarizing plate 10.

The first release film 32 can be used to cover and protect the surface of the first pressure-sensitive adhesive layer 31 opposite to the polarizing plate 10. The first release film 32 is peelable from the first pressure-sensitive adhesive layer 31.
The first release film 32 does not have a hole in the area where the hole 15 of the polarizing plate 10 is located.

In the optical laminate 2, when the polarizing plate 10 has a protective layer on only one surface, it preferably has a protective layer (first protective layer 12a in FIG. 3) on the side on which the first pressure-sensitive adhesive layer 31 is not provided.
The optical laminate 2 does not necessarily have to have the first release film 32 .

The optical laminate 2 can be obtained, for example, by laminating a first adhesive sheet having a first adhesive layer 31 provided on a first release film 32 onto the polarizing plate 10 described above, and then filling the holes 15 with a filler material 20.

The optical laminate 2 can also be obtained by laminating the first adhesive sheet to a polarizing plate in which no hole 15 is formed, forming a hole 15 only in the polarizing plate, and filling the hole 15 with a filler 20.

The optical laminate 2 may be obtained by laminating the first adhesive sheet onto the optical laminate 1 (Figure 2).

The optical laminate 2 can also be obtained by the following procedure. First, a laminate (1) is obtained by laminating an adhesive sheet having a first adhesive layer 31 provided on a release film onto a polarizing plate in which no hole 15 is formed. Next, in order to form the hole 15 of the polarizing plate 10, a hole is formed penetrating the entire laminate (1) in the lamination direction, and then the release film is peeled off. A first release film 32 is laminated on the first adhesive layer 31 exposed by the peeling, thereby obtaining a laminate (2). Furthermore, the hole in the laminate (2) is filled with a filler 20 to obtain the optical laminate 2.

The optical laminate 2 can also be obtained by the following procedure. First, a protective film is laminated on the first protective layer 12a side of the polarizing plate 10 having a hole 15 that is not filled with a filler. Next, the material of the filler 20 is injected into the hole 15, and further, an adhesive for forming a first adhesive layer 31 is coated on the surface of the polarizing plate 10 opposite the protective film. Then, the coated adhesive and the material of the filler 20 are cured by heating at the same time. By this curing, a first adhesive layer 31 is formed on the surface of the polarizing plate 10 opposite the protective film, and a first release film 32 is laminated on the surface of the first adhesive layer 31 opposite the polarizing plate 10. The protective film laminated on the polarizing plate 10 can be peeled off and removed as necessary.
When the material constituting the filler 20 is an adhesive, the injection of the adhesive into the holes in the polarizing plate and the application of the adhesive to the polarizing plate may be performed simultaneously.

The first adhesive layer 31 is formed using an adhesive, and the adhesives that can be used are those described above.

The thickness of the first adhesive layer 31 is not particularly limited, and may be 10 μm or more, 15 μm or more, or 20 μm or more. The thickness of the first adhesive layer 31 is usually 50 μm or less, and may be 40 μm or less, 30 μm or less, or 25 μm or less.

As the first release film 32, for example, a resin film having a release treatment applied to the side in contact with the first pressure-sensitive adhesive layer 31 can be used.
Examples of the resin film include films made of polyethylene-based resins such as polyethylene, polypropylene-based resins such as polypropylene, and polyester-based resins such as polyethylene terephthalate.
The release treatment may be silicone coating or the like.

The thickness of the first release film 32 is not particularly limited and may be 20 μm or more, or 25 μm or more, and is usually 50 μm or less, and may be 40 μm or less, or 30 μm or less.

The release film can be the one exemplified as the first release film 32.

(Another example of the optical laminate [2])
FIG. 4 is a schematic cross-sectional view showing still another example of the optical laminate of the present invention.
The optical laminate 3 shown in Fig. 4 has a second pressure-sensitive adhesive layer 41 and a second release film 42, in this order, on the first protective layer 12a (the other surface of the polarizing plate 10) of the optical laminate 2 shown in Fig. 3. The second pressure-sensitive adhesive layer 41 is provided so as to be in direct contact with the polarizing plate 10 of the optical laminate 2.

The second adhesive layer 41 can be used as an attachment layer for attaching to the second functional layer (cover member, touch sensor panel, etc.) described below.

The second release film 42 can be used to cover and protect the surface of the second pressure-sensitive adhesive layer 41 opposite to the polarizing plate 10. The second release film 42 is peelable from the second pressure-sensitive adhesive layer 41.
The optical laminate 3 does not necessarily have to have the second release film 42 .

In the optical laminate 3 shown in FIG. 4, a filler 20 is provided in the hole 15 of the polarizing plate 10, so that problems such as peeling of the second adhesive layer 41 and light leakage can be suppressed when the optical laminate 3 is placed in a high-temperature environment (e.g., at a temperature of 85°C for 100 hours).

In the optical laminate 3, the filler 20 is preferably the same adhesive as the adhesive constituting the second adhesive layer 41. By using the same material for the adhesive constituting the filler 20 and the adhesive constituting the first adhesive layer 31, the optical laminate 3 can be manufactured efficiently. This makes it possible to suppress a decrease in camera sensitivity and a decrease in design when a camera lens or a printed part such as an icon or logo is placed in the area where the hole 15 is located when the optical laminate 3 is applied to a display device.

The optical laminate 3 can be obtained, for example, by laminating a second adhesive sheet having a second adhesive layer 41 provided on a second release film 42 onto the polarizing plate 10 of the optical laminate 2 described above.

Since the optical laminate 2 (Figure 3) is used to laminate the second adhesive sheet, it is possible to prevent foreign matter from entering the hole 15 or air bubbles from entering the area around the hole 15 when laminating the optical laminate 2 and the second adhesive sheet.
In particular, the optical laminate 2 is provided with a first adhesive layer 31 and a first release film 32, and one side of the hole 15 is blocked by the first adhesive layer 31 and the first release film 32. When laminating the optical laminate 2 having a hollow hole and the second adhesive sheet, it is necessary to laminate the optical laminate 2 and the second adhesive sheet under vacuum conditions or vacuum heating conditions so as not to introduce foreign matter into the hole or generate air bubbles around the hole. In contrast, when laminating the optical laminate 2 having the hole filled with the filler 20 and the second adhesive sheet, the introduction of foreign matter or air bubbles can be suppressed even if the lamination is not performed under vacuum conditions or vacuum heating conditions. However, in order to further suppress the introduction of foreign matter or air bubbles at the bonding surface between the optical laminate 2 and the second adhesive sheet, the optical laminate 2 and the second adhesive sheet may be laminated under vacuum conditions or vacuum heating conditions.

When the optical laminate 3 is a long body, the optical laminate 2 (FIG. 3) and the second adhesive sheet are usually laminated continuously. When an optical laminate having a hollow hole is used, the speed of laminating the second adhesive sheet needs to be slowed down so as to suppress the inclusion of the above-mentioned foreign matter and air bubbles, as compared with the case where an optical laminate without a hollow hole is used.
By using an optical laminate 2 in which the holes are filled with filler 20, the lamination of the optical laminate 2 and the second adhesive sheet can be performed at approximately the same speed as when an optical laminate without hollow holes is used.

The second adhesive layer 41 can be formed using an adhesive. The adhesives that can be used include those described above.

In the optical laminate 3, when the filler 20 is the same adhesive as the adhesive constituting the second adhesive layer 41, the optical laminate 2 (FIG. 3) and the second adhesive sheet are preferably laminated under heating conditions (for example, at a temperature of 50° C. to 70° C.). By laminating under heating conditions, the adhesive constituting the second adhesive layer 41 and the adhesive constituting the filler 20 are easily assimilated (integrated). This makes it difficult to distinguish the boundary between the second adhesive layer 41 and the filler 20, thereby suppressing changes in the refractive index at the portion where the filler 20 and the second adhesive layer 41 come into contact.

The optical laminate 3 can also be obtained by the following procedure.
First, a first adhesive sheet having a first adhesive layer 31 provided on a first release film 32 is laminated on a polarizing plate 10 having a hollow hole 15. Next, a material of a filler 20 is injected so as to fill the hole 15 of the polarizing plate 10, and further, an adhesive for forming a second adhesive layer 41 is applied to the surface side of the polarizing plate 10 opposite to the first adhesive sheet. Then, the applied adhesive and the material of the filler 20 are cured by heating at the same time. By this curing, a second adhesive layer 41 is formed on the surface side of the polarizing plate 10 opposite to the first adhesive sheet, and a second release film 42 is laminated on the surface side of the second adhesive layer 41 opposite to the polarizing plate 10.
When the material constituting the filler 20 is an adhesive, the injection of the adhesive into the holes in the polarizing plate and the application of the adhesive to form the second adhesive layer 41 may be performed simultaneously.

The optical laminate 3 can also be obtained by the following procedure.
First, a second adhesive sheet having a second adhesive layer 41 provided on a second release film 42 is laminated on a polarizing plate 10 having a hollow hole 15. Next, the material of the filler 20 is injected so as to fill the hole 15 of the polarizing plate 10, and further, an adhesive for forming a first adhesive layer 31 is applied to the surface side of the polarizing plate 10 opposite the second adhesive sheet. Then, the applied adhesive and the material of the filler 20 are cured by heating at the same time. By this curing, a first adhesive layer 31 is formed on the surface side of the polarizing plate 10 opposite the second adhesive sheet, and a first release film 32 is laminated on the surface side of the first adhesive layer 31 opposite the polarizing plate 10.
When the material constituting the filler 20 is an adhesive, the injection of the adhesive into the holes in the polarizing plate and the application of the adhesive to form the first adhesive layer 31 may be performed simultaneously.

The thickness of the second adhesive layer 41 is not particularly limited and may be 80 μm or more, 100 μm or more, or 120 μm or more. The thickness of the second adhesive layer 41 is usually 200 μm or less, and may be 180 μm or less, or 150 μm or less.

As the second release film 42, for example, a resin film having a release treatment applied to the side in contact with the second pressure-sensitive adhesive layer 41 can be used.
As the resin film and the release treatment, for example, those exemplified for the first release film 32 can be used.

The thickness of the second release film 42 is not particularly limited and may be 20 μm or more, 30 μm or more, and is usually 100 μm or less, may be 80 μm or less, or may be 60 μm or less.

(Another example of the optical laminate [3])
FIG. 5 is a schematic cross-sectional view showing another example of the optical laminate of the present invention.
The optical laminate 4 shown in Figure 5 is an optical laminate having the same laminate structure as the laminate obtained by peeling off the first release film 32 from the optical laminate 3 shown in Figure 4, and an image display element layer 33 is laminated on the first adhesive layer 31.
The optical laminate 4 does not necessarily have to have the second release film 42 .

Examples of the image display element layer 33 include a layer including a display element such as a liquid crystal display element, such as a liquid crystal panel included in a liquid crystal display device, or an organic EL element included in an organic EL display device.

The optical laminate 4 can be obtained, for example, by peeling off the first release film 32 from the optical laminate 3 (Figure 4) and then bonding the exposed first adhesive layer 31 to the image display element layer 33.

The optical laminate 4 can also be obtained by the following procedure.
First, a first adhesive sheet having a first adhesive layer 31 provided on a first release film 32 is laminated on a polarizing plate 10 having a hollow hole 15, and then the first release film 32 is peeled off. The first adhesive layer 31 exposed by peeling off the first release film 32 is bonded to the image display element layer 33, and then the hole 15 is filled with a filler 20. Further, a second adhesive sheet having a second adhesive layer 41 provided on a second release film 42 is laminated on the surface of the polarizing plate opposite to the first adhesive layer 31, thereby obtaining an optical laminate 4.

(Another example of the optical laminate [4])
6(a) and (b) are schematic cross-sectional views showing still another example of the optical laminate of the present invention.
The optical laminates 5a and 5b shown in Figures 6(a) and (b) include a first functional layer 34 between the polarizing plate 10 and the first pressure-sensitive adhesive layer 31 in the optical laminate 3 shown in Figure 4. Specifically, the optical laminates 5a and 5b have a second pressure-sensitive adhesive layer 41 and a second release film 42, in this order, on the first protective layer 12a side of the optical laminate 1 shown in Figure 2, and have a first functional layer 34, a first pressure-sensitive adhesive layer 31, and a first release film 32, in this order, on the second protective layer 12b side of the optical laminate 1.

In the optical laminates 5a and 5b, when the polarizing plate 10 has a protective layer on only one surface, it preferably has a protective layer (first protective layer 12a in FIG. 3) on the side on which the second pressure-sensitive adhesive layer 41 is provided.
The optical laminates 5 a and 5 b may not have the first release film 32 .
The optical laminates 5 a and 5 b may have an image display element layer on the first pressure-sensitive adhesive layer 31 instead of the first release film 32 .
The optical laminates 5 a and 5 b may not have the second release film 42 .

A bonding layer may be provided between the optical laminate 1 and the first functional layer 34. The bonding layer is an adhesive layer formed from an adhesive, or an adhesive layer formed from an adhesive. Examples of the adhesive and adhesive constituting the bonding layer include those described above.

The first functional layer 34 may be at least one of an optical film and a touch sensor panel. When the first functional layer 34 includes both an optical film and a touch sensor panel, it is preferable that the first functional layer 34 has the optical film and the touch sensor panel in this order from the polarizing plate 10 side. The optical laminates 5a and 5b may further have a hard coat layer in addition to the first functional layer 34. The first functional layer 34 of the optical laminates 5a and 5b may have a structure in which two or more optical films are laminated.

When an optical film is used as the first functional layer 34, the optical film may have a hole in the region where the hole 15 of the polarizing plate 10 is located. In this case, as shown in FIG. 6(b), it is preferable to provide a filler 20 in the hole of the optical film (first functional layer 34) in the optical laminate 5b.

In the optical laminates 5a and 5b shown in Figures 6(a) and (b), the holes 15 in the polarizing plate 10 are filled with the filler 20, so that problems such as peeling of the second adhesive layer 41 and light leakage can be suppressed when the laminate is left in a high-temperature environment (e.g., at a temperature of 85°C for 100 hours).

The optical laminate 5a shown in FIG. 6(a) can be obtained by the following procedure.
A first functional layer 34 is provided on a polarizing plate 10 having a hollow hole 15, and a first adhesive sheet having a first adhesive layer 31 provided on a first release film 32 is laminated on the first functional layer 34. The hole 15 is then filled with a filler 20 to obtain a laminate (3). Next, a second adhesive sheet having a second adhesive layer 41 provided on a second release film 42 is laminated on the polarizing plate 10 of the laminate (3) to obtain an optical laminate 5a.

The laminate (3) may be obtained by providing a first functional layer 34 on the optical laminate 1 (FIG. 2) described above, and laminating the first adhesive sheet described above on the first functional layer 34 in the resulting laminate (3).

The optical laminate 5b shown in FIG. 6(b) can be obtained by the following procedure.
First, a first functional layer 34 is provided on a polarizing plate having a polarizing layer 11 and a protective layer 12 provided on one or both sides thereof to obtain a laminate (4).
Furthermore, a hole is formed so as to penetrate the entire laminate (4) in the lamination direction, and a first adhesive sheet having a first adhesive layer 31 provided on a first release film 32 is laminated to obtain a laminate (5). After providing a filler 20 in the hole of the laminate (5), the above-mentioned second adhesive sheet is laminated on the surface of the polarizing plate 10 opposite to the first adhesive layer 31 to obtain an optical laminate 5b.
When the optical laminate 5 b is manufactured by the above procedure, holes are also formed in the first functional layer 34 , and these holes are also filled with the filling material 20 .
When holes are also provided in the first pressure-sensitive adhesive layer 31, the laminate (5) may be obtained by the following procedure: A pressure-sensitive adhesive sheet having the first pressure-sensitive adhesive layer 31 provided on a release film is laminated on the first functional layer 34 of the laminate (4) to obtain a laminate.
Next, a hole is formed so as to penetrate the entire laminate, and then the release film is peeled off and a first release film 32 is laminated, thereby obtaining the laminate (5).

The lamination of the second adhesive sheet may be performed under vacuum conditions. If the filler 20 of the optical laminates 5a and 5b is the same adhesive as that constituting the second adhesive layer 41, it is preferable to perform the lamination under heated conditions (for example, at a temperature of 50°C to 70°C).

As described above, by laminating the second adhesive sheet while the hole 15 of the polarizing plate 10 is filled with the filler 20, it is possible to prevent foreign matter from entering the hole 15 or air bubbles from entering the area around the hole 15.

Examples of the optical film include a retardation film (a resin film or a cured film obtained by aligning and polymerizing a polymerizable liquid crystal compound), a reflective film, a semi-transmissive reflective film, a brightness enhancing film, an optical compensation film, a film with an anti-glare function, etc. The optical film may be one layer or two or more layers, and when two or more layers are used, they may be the same optical film or different optical films.
The optical film may be a λ/4 wavelength plate, a laminated film of a λ/4 wavelength plate and a λ/2 wavelength plate, or a laminated film of a λ/4 wavelength plate with reverse wavelength dispersion and a positive C plate. When the optical film is a laminated film, an attachment layer (adhesive layer or pressure-sensitive adhesive layer) may be interposed between the films.

A touch sensor panel is a sensor that can detect a position touched by a finger, a touch pen, or the like. There are no particular limitations on the detection method of the touch sensor panel, and examples include touch sensor panels of the resistive film type, electrostatic capacitance coupling type, optical sensor type, ultrasonic type, electromagnetic induction coupling type, and surface acoustic wave type. Resistive film type and electrostatic capacitance coupling type touch sensor panels are preferably used because of their low cost.

Examples of hard coat layers include layers made of resins such as triacetyl cellulose and acrylic resins.

(Another example of the optical laminate [5])
FIG. 7 is a schematic cross-sectional view showing still another example of the optical laminate of the present invention.
The optical laminate 6 shown in Figure 7 is obtained by laminating a second functional layer 44 on the second adhesive layer 41 of the optical laminate obtained by peeling off the second release film 42 from the optical laminate 3 shown in Figure 4.

The optical laminate 6 does not necessarily have to have the first release film 32 .
The optical laminate 6 may have an image display element layer on the first pressure-sensitive adhesive layer 31 in place of the first release film 32 .

The second functional layer 44 may be at least one of a cover member and a touch sensor panel. When the second functional layer 44 includes both a cover member and a touch sensor panel, it is preferable that the second functional layer 44 has the touch sensor panel and the cover member in this order from the second adhesive layer 41 side.

The optical laminate 6 can be obtained by laminating the second functional layer 44 on the second adhesive layer 41 exposed by peeling off the second release film 42 of the optical laminate 3 shown in FIG. 4.

The cover member can be used as the outermost surface of a display device or the like. The cover member is a light-transmitting (preferably optically transparent) plate-like body. The cover member may have a single-layer structure or a multi-layer structure.

The cover member is preferably made of an inorganic material such as glass or reinforced glass, or a resin film having a Young's modulus of 2 GPa or more. Inorganic materials such as glass and reinforced glass, particularly resin films are suitable for flexible display applications in order to make them bendable, and among these, polyamide films, polyamideimide films, polyimide films, polyester films, olefin films, acrylic films, and cellulose films are preferred. It is also preferred to disperse inorganic particles such as silica, organic fine particles, rubber particles, etc. in the polymer film.
The bendable cover member made of a resin film may have a hard coat layer on at least one surface thereof The hard coat layer can be provided on the surface of the resin film by a known method.

Examples of touch sensor panels include those mentioned above.

(Uses of optical laminate)
The optical laminates 1 to 4, 5a, 5b, and 6 can be used in display devices such as liquid crystal display devices and organic EL display devices. Examples of the display devices include mobile devices such as smartphones and tablets, televisions, digital photo frames, electronic signboards, measuring instruments and gauges, office equipment, medical equipment, and computing equipment.
In the optical laminates 5a, 5b, and 6, when the laminated member is a touch sensor panel, it can be used in touch panel display devices such as smartphones and tablets.

1 to 4, 5a, 5b, 6 Optical laminate, 10 Polarizing plate, 11 Polarizing layer, 12 Protective layer, 12a First protective layer, 12b Second protective layer, 20 Filler, 31 First adhesive layer, 32 First release film, 33 Image display element layer, 34 First functional layer, 41 Second adhesive layer, 42 Second release film, 44 Second functional layer.

Claims (14)

a polarizing plate including a polarizing layer and a protective layer provided on one or both sides of the polarizing layer, the polarizing layer having a hole penetrating the polarizing layer and the protective layer in a lamination direction;
The hole is filled with a light-transmitting filling material,
A first pressure-sensitive adhesive layer is provided on one surface of the polarizing plate,
a first release film is provided on the surface of the first pressure-sensitive adhesive layer opposite to the polarizing plate;
a second pressure-sensitive adhesive layer in direct contact with the other surface of the polarizing plate;
a second release film is provided on the surface of the second pressure-sensitive adhesive layer opposite to the polarizing plate;
the first pressure-sensitive adhesive layer, the first release film, the second pressure-sensitive adhesive layer, and the second release film do not have a hole in a region where the hole of the polarizing plate is located,
The optical laminate , wherein the filler is provided throughout the hole of the polarizing plate . The optical laminate according to claim 1 , wherein the filler comprises a resin. The optical laminate according to claim 1 , wherein the polarizing plate has a thickness of 15 μm or more. 4. The optical laminate according to claim 1, wherein the hole of the polarizing plate has a diameter of 0.5 mm or more and 20 mm or less. The optical laminate according to any one of claims 1 to 4 , wherein the first pressure-sensitive adhesive layer is provided so as to be in direct contact with the polarizing plate. The optical laminate according to any one of claims 1 to 4 , further comprising a first functional layer between the polarizing plate and the first pressure-sensitive adhesive layer. The optical laminate according to claim 6 , wherein the first functional layer includes at least one of an optical film and a touch sensor panel. The first functional layer includes the optical film,
The optical laminate according to claim 7, wherein the optical film is a λ/4 wavelength plate, a laminate film of a λ/4 wavelength plate and a λ/2 wavelength plate, or a laminate film of a λ/4 wavelength plate having reverse wavelength dispersion and a positive C plate. the first functional layer has a hole formed in a region where the hole of the polarizing plate is located,
The optical laminate according to claim 6 , wherein the holes of the first functional layer are filled with the filler. The optical laminate according to any one of claims 1 to 9 , wherein the filler is the same adhesive as the adhesive constituting the second adhesive layer. The optical laminate according to any one of claims 1 to 10 , which is a long body. The optical laminate according to any one of claims 1 to 11 , wherein the protective layer is provided on both sides of the polarizing layer. The optical laminate according to any one of claims 1 to 12 , wherein the first pressure-sensitive adhesive layer covers the entirety of the one surface side of the polarizing plate. The optical laminate according to any one of claims 1 to 13 , wherein the second pressure-sensitive adhesive layer covers the entirety of the other surface of the polarizing plate.

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