JP7706924B2 - Method for producing optical laminate - Google Patents

Description

The present invention relates to a method for producing an optical laminate having at least a polarizing plate, a separator, and a surface protection film. In particular, the present invention relates to a method for producing an optical laminate capable of suppressing curling.

Conventionally, polarizing plates have been used as a component material for liquid crystal display devices, organic EL display devices, and the like. In addition to a polarizing film, the polarizing plate includes a retardation film or the like depending on the application. The polarizing film is composed of, for example, a polarizer dyed with a dichroic substance such as iodine and a protective film that protects the polarizer. A long strip-shaped polarizing film is manufactured by laminating a long strip-shaped protective film to at least one side of a long strip-shaped polarizer. A long strip-shaped retardation film or the like is laminated to one side of the manufactured long strip-shaped polarizing film to manufacture a long strip-shaped polarizing plate. A long strip-shaped separator (release film) is laminated to one side of the manufactured long strip-shaped polarizing plate, and a long strip-shaped surface protective film is laminated to the other side to manufacture a long strip-shaped optical laminate. The lamination of these long strip-shaped films is usually performed by a roll-to-roll method or a roll-to-sheet method. The manufactured long strip-shaped optical laminate is cut to a size and shape depending on the application and used in a liquid crystal display device or the like. When used in a liquid crystal display device, the separator is peeled off and the remaining components of the optical laminate are attached to the liquid crystal display device.

8 is a flow diagram showing an example of a schematic process of a conventional method for producing an optical laminate. As shown in FIG. 8, the conventional method for producing an optical laminate includes a polarizing film production process ST1′, a retardation film attachment process ST2′, a separator attachment process ST3′, an inspection process ST4′, and a surface protection film attachment process ST5′.
In the polarizing film manufacturing process ST1', a long strip-shaped resin film is used as a raw film, and the raw film is immersed in various treatment baths while being transported in the longitudinal direction, and various treatments such as dyeing and stretching are performed to manufacture a long strip-shaped polarizer. A long strip-shaped protective film is then attached to at least one surface of the long strip-shaped polarizer to manufacture a long strip-shaped polarizing film.
In the retardation film laminating step ST2', a long strip-shaped retardation film (such as a half wave plate or a quarter wave plate) is laminated to one side of a long strip-shaped polarizing film to produce a long strip-shaped polarizing plate.

In the separator lamination step ST3', a long strip-shaped separator is coated with an adhesive while being transported in the longitudinal direction, and the coated adhesive is heated in an oven or the like to dry and harden to form an adhesive layer. Then, the adhesive layer side of this long strip-shaped separator (separator with adhesive layer) is laminated to one side of a long strip-shaped polarizing plate to produce a long strip-shaped intermediate in which the polarizing plate, the adhesive layer, and the separator are laminated.
In the inspection step ST4', the separator is peeled off while the adhesive layer between the separator and the polarizing plate is left on the polarizing plate side, and the polarizing plate is inspected. Examples of the inspection method for the polarizing plate include a transmission inspection, a crossed Nicol inspection, and a reflection inspection. In the inspection step ST4', after the polarizing plate is inspected, the peeled separator is attached to the polarizing plate again to return it to the original intermediate state.

In the surface protective film laminating step ST5', a long strip-shaped surface protective film is laminated to the surface of the long strip-shaped polarizing plate opposite to the surface to which the separator is laminated.
Through the above-described polarizing film manufacturing step ST1' to surface protective film bonding step ST5', a long strip-shaped optical laminate is manufactured.

However, the optical laminate produced as described above may suffer from curling (warping of the edges) that is problematic in use after being cut into a product size.
For example, Patent Document 1 proposes using a specific material for a protective film that protects a polarizer as a method for suppressing curling of a polarizing film, but the material of the protective film is limited and is not versatile. A method capable of suppressing curling without particularly changing the materials of the components of a conventionally used optical laminate is desired.

JP 2007-256568 A

The present invention has been made to solve the problems of the conventional technology described above, and aims to provide a method for manufacturing an optical laminate that can suppress curling.

In order to solve the above problem, the present inventors have conducted intensive research and found that the formation of an adhesive layer on a separator in a separator lamination step (ST3' in FIG. 8) in a conventional method for producing an optical laminate may be one of the causes of curling of the optical laminate. Specifically, it is considered that when the adhesive applied to the separator is heated and dried, the separator shrinks and unevenness occurs in its thickness direction. When the separator is laminated to a polarizing plate in the separator lamination step, or when the separator is laminated to a polarizing plate again in the inspection step (ST4' in FIG. 8), the separator is laminated in a state in which the unevenness generated in the separator is stretched by heating, but after a time has passed since lamination, a force acts on the separator to return to the contracted state, which is considered to cause curling in the optical laminate.
As a result of further intensive investigations focusing on the above-mentioned factors, the present inventors have found that performing the step of peeling off the separator and then laminating the separator as in the conventional inspection step after the surface protection film laminating step (ST5' in FIG. 8) is effective in suppressing the occurrence of curling. That is, since the laminate to which the surface protection film is laminated has higher rigidity than the laminate before the surface protection film is laminated, it has been found that if a separator with its irregularities stretched out is laminated to this highly rigid laminate, curling is unlikely to occur even if a force acts to return the separator to its contracted state.
The present invention has been completed based on the above findings of the present inventors.

That is, in order to solve the above-mentioned problem, the present invention provides a method for producing an optical laminate, comprising: a separator bonding step of bonding a long strip-shaped separator to a long strip-shaped polarizing plate via an adhesive layer formed on the separator; a second separator peeling/bonding step of peeling the long strip-shaped separator from the adhesive layer after the separator bonding step, and then bonding the long strip- shaped separator to the polarizing plate via the adhesive layer after the second separator peeling/bonding step; a surface protective film bonding step of bonding a long strip-shaped surface protective film to the side of the polarizing plate opposite to the side to which the separator is bonded after the second separator peeling/bonding step; and a first separator peeling/bonding step of peeling the long strip-shaped separator from the adhesive layer after the surface protective film bonding step, and then bonding the long strip-shaped separator to the polarizing plate via the adhesive layer.

In the first separator peeling/attaching step of the present invention, the peeled separator and the separator to be attached may be the same separator or different separators. That is, the first separator peeling/attaching step of the present invention includes a case where the separator is peeled from the adhesive layer (only the separator is peeled while the adhesive layer remains on the polarizing plate) and then the same separator is attached again to the polarizing plate via the adhesive layer. In addition, the first separator peeling/attaching step also includes a case where a new separator different from the peeled separator (i.e., a separator that is not heated to form an adhesive layer and therefore is unlikely to cause unevenness) is attached (reattached) to the polarizing plate via the adhesive layer.
According to the present invention, the first separator peeling/laminating step is included, so that the separator is peeled off and laminated. In other words, even if the separator to be laminated is the same as the separator to be peeled off, the separator is laminated to the polarizing plate in a state in which the irregularities of the separator are stretched out. Since the first separator peeling/laminating step is performed after the surface protection film laminating step, the separator in a state in which the irregularities are stretched out is laminated to the highly rigid laminate, and curling can be suppressed even if a force acts on the separator to return it to its contracted state.
In the second separator peeling/laminating step, the peeled separator and the separator to be laminated may be the same or different separators, as in the first separator peeling/laminating step. By including the second separator peeling/laminating step, the separator is peeled and laminated not only after the surface protective film laminating step, but also before the surface protective film laminating step. In other words, even if the separator to be laminated is the same as the separator to be peeled, the separator is laminated to the polarizing plate in a state in which the irregularities of the separator are stretched, so that curling can be further suppressed.

The separator lamination process includes, for example, an adhesive layer formation process in which an adhesive is applied to a long strip-shaped separator and the applied adhesive is heated and cured to form the adhesive layer.

Preferably, the second separator peeling/attaching step also serves as an inspection step of inspecting the polarizing plate after the long strip-shaped separator is peeled off.
According to the above-mentioned preferred method, the second separator peeling/bonding step also serves as an inspection step for the polarizing plate, which has the advantage that the manufacturing process is simpler than when the second separator peeling/bonding step and the inspection step are provided separately.

Preferably, in the first separator peeling/laminating step, the time from peeling the long strip separator to laminating the long strip separator is within one minute.
According to the above-mentioned preferred method, the time from peeling off the long strip separator to bonding the long strip separator, in other words, the time for the adhesive layer to be exposed, is short, so that even if the humidity in the first separator peeling/bonding process changes due to, for example, seasonal influences or daytime or nighttime influences, it is possible to suppress variations in curling caused by the polarizing plate absorbing moisture in the atmosphere from the adhesive layer side and swelling.
In addition, in the case where the present invention includes a second separator peeling/laminating step, it is also preferable that the time from peeling the long strip separator to laminating the long strip separator in the second separator peeling/laminating step is within 1 minute.

Preferably, in the first separator peeling/laminating process, the long strip separator and the polarizing plate are laminated together by a laminating roller, the separator has an approach angle to the laminating roller of less than 90°, and the polarizing plate has an approach angle to the laminating roller of less than 90°.

In the above-mentioned preferred method, the "approach angle of the separator to the lamination roller" means the angle between a vector perpendicular to a line passing through the rotation center of a pair of opposing rollers constituting the lamination roller, pointing to the exit side of the lamination roller, and a vector indicating the proceeding direction of the separator until it comes into contact with the lamination roller. Similarly, the "approach angle of the polarizing plate to the lamination roller" means the angle between a vector perpendicular to a line passing through the rotation center of a pair of rollers constituting the lamination roller, pointing to the exit side of the lamination roller, and a vector indicating the proceeding direction of the polarizing plate until it comes into contact with the lamination roller.
According to the findings of the inventors, when the approach angle of the separator to the lamination roller is large (90° or more), the curl in the TD direction (direction perpendicular to the transport direction (MD direction) of the long, strip-shaped optical laminate) and negative curl (curl in which the side where the separator is located is concave) becomes large, and when the approach angle of the polarizing plate to the lamination roller is large (90° or more), the curl in the TD direction and positive curl (curl in which the side where the separator is located is convex) becomes large.
According to the above-mentioned preferable method, by making both the approach angles of the separator and the polarizing plate to the lamination roller less than 90°, curling can be further suppressed.
In addition, when the present invention includes a second separator peeling/laminating step, it is similarly preferable that in the second separator peeling/laminating step, the long strip separator and the polarizing plate are bonded together by a laminating roller, the approach angle of the separator to the laminating roller is less than 90°, and the approach angle of the polarizing plate to the laminating roller is less than 90°.

Preferably, the lamination roller is composed of a first roller that contacts the separator and a second roller that contacts the polarizing plate, and one surface of the first roller and the second roller is formed from resin and the other surface is formed from metal.
If both the surface of the first roller and the surface of the second roller are made of metal, there is a risk of air bubbles being generated at the interface between the separator and the polarizing plate (the interface between the separator and the adhesive layer) when the separator and the polarizing plate are bonded together. If both the surface of the first roller and the surface of the second roller are made of resin, there is a risk of wrinkles being generated in the separator.
According to the above-described preferred method, the surface of one of the first roller and the second roller is formed from resin, and the surface of the other is formed from metal, thereby making it possible to suppress the risk of air bubbles or wrinkles being generated.
In addition, in the case where the present invention includes a second separator peeling/laminating step, similarly in the second separator peeling/laminating step, the laminating roller is composed of a first roller that contacts the separator and a second roller that contacts the polarizing plate, and it is preferable that one surface of the first roller and the second roller is formed from resin and the other surface is formed from metal.

Preferably, the surface of the first roller is made of metal, and the surface of the second roller is made of resin.
According to the above-mentioned preferred method, in addition to being able to reduce the risk of air bubbles and wrinkles occurring, since the surface of the second roller that comes into contact with the polarizing plate is formed from resin (and not from metal), it is possible to reduce the occurrence of appearance defects on the polarizing plate such as scratches and dents.
In addition, in the case where the present invention includes a second separator peeling/laminating step, it is preferable that the surface of the first roller is formed from a metal and the surface of the second roller is formed from a resin, similarly for the second separator peeling/laminating step.

According to the present invention, curling can be effectively suppressed without any particular changes to the materials of the components of conventionally used optical laminates.

1 is a cross-sectional view showing a schematic configuration of an optical laminate produced by a production method according to one embodiment of the present invention. FIG. 1 is a flow diagram showing schematic steps of a method for producing an optical laminate according to one embodiment of the present invention. 3 is a side view (as viewed from a horizontal direction perpendicular to the transport direction of each film) showing a schematic configuration example of an apparatus that performs the inspection process ST4 shown in FIG. 2. FIG. 3 is a side view (as viewed from a horizontal direction perpendicular to the conveying direction of each film) that illustrates a schematic configuration example of an apparatus that performs the first separator peeling/bonding step ST6 illustrated in FIG. 2 . 5 is an explanatory diagram illustrating lamination of the third intermediate M3 and the separator 4b by the laminating roller R7 shown in FIG. 4. FIG. 3 is a side view (as viewed from a horizontal direction perpendicular to the conveying direction of each film) that illustrates a schematic configuration example of an apparatus that performs a modified example of the first separator peeling/bonding step ST6 illustrated in FIG. 2 . FIG. 2 is an explanatory diagram for explaining a method for evaluating curl. FIG. 1 is a flow chart showing an example of schematic steps of a conventional method for producing an optical laminate.

Below, we will explain the manufacturing method of an optical laminate according to one embodiment of the present invention, with appropriate reference to the attached drawings. Please note that each figure is shown for reference only, and the dimensions, scale, and shapes of the optical laminate and device components shown in each figure may differ from the actual ones.

<Configuration of optical laminate>
First, the configuration of the optical laminate produced by the production method according to this embodiment will be described.
FIG. 1 is a cross-sectional view that illustrates a schematic configuration of an optical laminate produced by a production method according to this embodiment.
As shown in Fig. 1, the optical laminate 100 of this embodiment includes a polarizing film 1, a retardation film 2, a pressure-sensitive adhesive layer 3, a separator 4, and a surface protection film 5. A laminate of the polarizing film 1 and the retardation film 2 constitutes a polarizing plate 10. A laminate of the polarizing plate 10 and the pressure-sensitive adhesive layer 3 constitutes a first intermediate M1. A laminate of the first intermediate M1 and the separator 4 constitutes a second intermediate M2. A laminate of the first intermediate M1 and the surface protection film 5 constitutes a third intermediate M3. Each component of the optical laminate 100 will be described below.

[Polarizing film 1]
The polarizing film 1 is composed of a polarizer 11 and protective films 12 and 13 that protect the polarizer 11. In this embodiment, the protective films 12 and 13 are bonded to both sides of the polarizer 11, but this is not limited thereto, and it is sufficient that a protective film is bonded to at least one side of the polarizer 11.

(Polarizer 11)
The polarizer 11 is typically made of a resin film containing a dichroic material.
As the resin film, any appropriate resin film that can be used as a polarizer can be adopted. The resin film is typically a polyvinyl alcohol-based resin (hereinafter, referred to as a "PVA-based resin") film.

As the PVA-based resin forming the PVA-based resin film, any appropriate resin can be used. For example, polyvinyl alcohol and ethylene-vinyl alcohol copolymer can be mentioned. Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. Ethylene-vinyl alcohol copolymer can be obtained by saponifying ethylene-vinyl acetate copolymer.

The average degree of polymerization of the PVA-based resin can be appropriately selected depending on the purpose. The average degree of polymerization is usually 1,000 to 10,000, preferably 1,200 to 4,500, and more preferably 1,500 to 4,300. The average degree of polymerization can be determined in accordance with JIS K 6726-1994.

Examples of dichroic substances contained in the resin film include iodine and organic dyes. These can be used alone or in combination of two or more. Iodine is preferably used.

The resin film may be a single-layer resin film or a laminate of two or more layers.

A specific example of a polarizer composed of a single-layer resin film is a PVA-based resin film that has been subjected to a dyeing treatment with iodine and a stretching treatment (typically, a uniaxial stretching treatment). The dyeing treatment with iodine is performed, for example, by immersing the PVA-based film in an aqueous iodine solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching may be performed after dyeing or while dyeing. Also, dyeing may be performed after stretching. If necessary, the PVA-based resin film is subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, etc.

Specific examples of polarizers made of a laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer made of a laminate of a resin substrate and a PVA-based resin layer applied to the resin substrate. A polarizer made of a laminate of a resin substrate and a PVA-based resin layer applied to the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate, drying the resin substrate to form a PVA-based resin layer on the resin substrate, obtaining a laminate of the resin substrate and the PVA-based resin layer, and then stretching and dyeing the laminate to make the PVA-based resin layer into a polarizer. In this embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching may include, as necessary, stretching the laminate in the air at a high temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. The obtained resin substrate/polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate/polarizer laminate, and any suitable protective layer may be laminated on the peeled surface depending on the purpose. Details of the method for producing such a polarizer are described, for example, in JP 2012-73580 A. The entire disclosure of this publication is incorporated herein by reference.

The thickness of the polarizer 11 is preferably 15 μm or less, more preferably 1 μm to 12 μm, even more preferably 3 μm to 10 μm, and particularly preferably 3 μm to 8 μm.

The polarizer 11 preferably exhibits absorption dichroism at any wavelength within the range of 380 nm to 780 nm. The single transmittance of the polarizer 11 is preferably 40.0% to 45.0%, and more preferably 41.5% to 43.5%. The degree of polarization of the polarizer 11 is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.

(Protective films 12, 13)
Any suitable resin film is used as the protective films 12 and 13. Examples of materials for forming the resin film include (meth)acrylic resins, cellulose resins such as diacetyl cellulose and triacetyl cellulose, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, ester resins such as polyethylene terephthalate resins, polyamide resins, polycarbonate resins, and copolymer resins thereof. Note that "(meth)acrylic resin" means acrylic resin and/or methacrylic resin. The materials for forming the protective films 12 and 13 may be the same or different from each other.

The thickness of the protective films 12 and 13 is typically 10 μm to 100 μm, and preferably 20 μm to 40 μm. The thicknesses of the protective films 12 and 13 may be the same or different.

The surface of the protective films 12, 13 opposite the polarizer 11 may be subjected to a surface treatment such as a hard coat treatment, an anti-reflection treatment, an anti-sticking treatment, or an anti-glare treatment, if necessary. Furthermore, the surface of the protective films 12, 13 opposite the polarizer 11 may be subjected to a treatment to improve visibility when viewed through polarized sunglasses (typically, a treatment to impart (elliptical) polarization function, a treatment to impart ultra-high phase difference), if necessary. Note that when a surface treatment layer is formed by performing a surface treatment, the thickness of the protective films 12, 13 includes the thickness of the surface treatment layer.

The protective films 12 and 13 are laminated to the polarizer 11 via any suitable adhesive layer (not shown). Typical examples of the adhesive that constitutes the adhesive layer include a PVA-based adhesive or an activated energy ray-curable adhesive.

[Retardation film 2]
The retardation film 2 may be, for example, a compensation plate that provides a wide viewing angle, or a retardation plate (circular polarizing plate) such as a half-wave plate or a quarter-wave plate that is used together with a polarizing film to generate circularly polarized light. The thickness of the retardation film 2 is, for example, 1 to 200 μm.

The retardation film 2 is formed of, for example, a layer or resin formed by polymerizing a polymerizable liquid crystal. The polymerizable liquid crystal is a compound having a polymerizable group and liquid crystallinity. The polymerizable group means a group involved in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group means a group that can be involved in a polymerization reaction by an active radical or an acid generated from a photopolymerization initiator. Examples of the polymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferable, and an acryloyloxy group is more preferable. The liquid crystallinity of the polymerizable liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal, and when the thermotropic liquid crystal is classified by the degree of order, it may be a nematic liquid crystal or a smectic liquid crystal.
Examples of the resin forming the retardation film 2 include polyarylate, polyamide, polyimide, polyester, polyaryletherketone, polyamideimide, polyesterimide, polyvinyl alcohol, polyfumaric acid ester, polyethersulfone, polysulfone, norbornene resin, polycarbonate resin, cellulose resin, and polyurethane. These resins may be used alone or in combination.

The retardation film 2 is laminated to the polarizing film 1 (protective film 13) via any suitable adhesive layer or pressure-sensitive adhesive layer (not shown). Typical examples of the adhesive that constitutes the adhesive layer include a PVA-based adhesive or an activated energy ray-curable adhesive.

[Pressure-sensitive adhesive layer 3]
The adhesive layer 3 is formed by applying an adhesive to one surface of the separator 4 and then heating and drying the applied adhesive in an oven or the like to harden it.
The heating temperature of the adhesive is preferably set in the range of 100° C. to 160° C., and more preferably in the range of 140° C. to 160° C. Heating at this heating temperature is preferably performed for 20 seconds to 3 minutes, and more preferably for 1 minute to 3 minutes.

Specific examples of adhesives forming the adhesive layer 3 include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the type, number, combination, and compounding ratio of the monomers forming the base resin of the adhesive, as well as the compounding amount of the crosslinking agent, reaction temperature, reaction time, etc., an adhesive having the desired properties according to the purpose can be prepared. The base resin of the adhesive may be used alone or in combination of two or more types. From the viewpoints of transparency, processability, durability, etc., acrylic adhesives are preferred. Details of the adhesives constituting the adhesive layer are described in, for example, JP 2014-115468 A, and the description of this publication is incorporated herein by reference. The thickness of the adhesive layer can be, for example, 10 μm to 100 μm.

[Separator 4]
Any appropriate separator can be used as the separator 4. Specific examples include plastic films, nonwoven fabrics, and paper whose surfaces are coated with a release agent. Specific examples of the release agent include silicone-based release agents, fluorine-based release agents, and long-chain alkyl acrylate-based release agents. Specific examples of the plastic film include polyethylene terephthalate (PET) films, polyethylene films, and polypropylene films. The thickness of the separator 4 can be, for example, 10 μm to 100 μm.

[Surface protection film 5]
The surface protection film 5 typically has a substrate and a pressure-sensitive adhesive layer. In this embodiment, the thickness of the surface protection film 5 is, for example, 30 μm or more. The upper limit of the thickness of the surface protection film 5 is, for example, 150 μm. In this specification, the "thickness of the surface protection film" refers to the total thickness of the substrate and the pressure-sensitive adhesive layer.

The substrate can be made of any suitable resin film. Examples of materials for forming the resin film include ester-based resins such as polyethylene terephthalate-based resins, cycloolefin-based resins such as norbornene-based resins, olefin-based resins such as polypropylene, polyamide-based resins, polycarbonate-based resins, and copolymer resins of these resins. Ester-based resins (particularly polyethylene terephthalate-based resins) are preferred.

Any suitable adhesive can be used as the adhesive that forms the adhesive layer. Examples of the base resin of the adhesive include acrylic resin, styrene resin, silicone resin, urethane resin, and rubber resin.

<Production method according to this embodiment>
A method for producing the optical laminate 100 according to this embodiment for producing the optical laminate 100 having the configuration described above will be described below.
FIG. 2 is a flow diagram showing an outline of the steps of a method for producing the optical laminate 100 according to this embodiment.
2, the manufacturing method according to the present embodiment includes a polarizing film manufacturing process ST1, a retardation film bonding process ST2, a separator bonding process ST3, an inspection process ST4 (which also serves as the second separator peeling/bonding process of the present invention), a surface protection film bonding process ST5, and a first separator peeling/bonding process ST6. Each of the processes ST1 to ST6 will be described below.

[Polarizing film manufacturing process ST1]
In the polarizing film manufacturing process ST1, a long strip-shaped resin film is used as a raw film, and this raw film is immersed in various treatment baths while being transported in the longitudinal direction (MD direction) and subjected to various treatments such as dyeing and stretching to manufacture a long strip-shaped polarizer 11. Then, long strip-shaped protective films 12 and 13 are bonded to the long strip-shaped polarizer 11 to manufacture a long strip-shaped polarizing film 1.

[Retardation film bonding process ST2]
In the retardation film laminating step ST2, a long strip of retardation film 2 is laminated to one surface (protective film 13) of a long strip of polarizing film 1, thereby producing a long strip of polarizing plate 10.
In addition, when the optical laminate 100 does not include the retardation film 2 (when the polarizing plate 10 does not include the retardation film 2), the retardation film bonding step ST2 is not necessary.

[Separator lamination process ST3]
In the separator lamination process ST3, an adhesive is applied to the long strip separator 4 while it is being transported in the longitudinal direction (MD direction), and the applied adhesive is heated in an oven or the like to dry and harden, thereby forming an adhesive layer 3. Then, the separator 4 is laminated to the long strip polarizing plate 10 via the adhesive layer 3 formed on the long strip separator 4. Specifically, the adhesive layer 3 side of the long strip separator 4 (separator 4 with adhesive layer 3) is laminated to one side (phase difference film 2) of the long strip polarizing plate 10. In this way, a second intermediate M2 in which the polarizing plate 10, the adhesive layer 3, and the separator 4 are laminated is manufactured.

[Inspection step (second separator peeling/bonding step) ST4]
The inspection process ST4 of this embodiment is performed before the surface protection film bonding process ST5. In the inspection process ST4, the long strip-shaped separator 4 is peeled off from the adhesive layer 3 (only the separator 4 is peeled off while the adhesive layer 3 interposed between the separator 4 and the polarizing plate 10 is left on the polarizing plate 10 side), and then the polarizing plate 10 is inspected. Then, after inspecting the polarizing plate 10, the peeled separator 4 is bonded again to the polarizing plate 10 to return it to the original state of the second intermediate M2.

3 is a side view (as viewed from a horizontal direction perpendicular to the transport direction of each film) showing a schematic configuration example of an apparatus that performs the inspection process ST4. The arrows shown in FIG. 3 indicate the transport direction of each film.
In the inspection process ST4, the second intermediate M2 manufactured in the separator laminating process ST3 as described above is wound around the pay-out roller R1 shown in Fig. 3 and disposed on the most upstream side of the apparatus (the most upstream side in the conveying direction of the second intermediate M2). Then, the second intermediate M2 paid out from the pay-out roller R1 is conveyed toward the peeling roller R2. At the peeling roller R2, the separator 4 is peeled off from the second intermediate M2, and the peeled separator 4 is conveyed toward the laminating roller R3.

On the other hand, the first intermediate M1, which is a laminate of the polarizing plate 10 and the adhesive layer 3 obtained by peeling the separator 4 from the second intermediate M2 by the peeling roller R2, is inspected by the inspection device 20.
The inspection device 20 shown in Fig. 3 is a device that performs a transmission inspection, and includes a light source 20a, an imaging means 20b, and a calculation means (not shown). The imaging means 20b of the inspection device 20 receives light emitted from the light source 20a and transmitted through the first intermediate M1, forms an image, and outputs an electrical signal according to the amount of light as an imaging signal to the calculation means. The calculation means generates a transmission image based on the input imaging signal. Then, the calculation means applies known image processing, such as binarization, to the generated transmission image to extract pixel areas that have a different luminance value (pixel value) from other pixel areas, thereby detecting defects present in the first intermediate M1 (polarizing plate 10).
The inspection performed in the inspection process ST4 is not limited to the above-mentioned transmission inspection. It is also possible to adopt a cross-Nicol inspection in which a cross-Nicol image is generated by light passing through the inspection polarizing filter and the first intermediate M1 arranged to be in cross-Nicol with respect to the polarization axis of the polarizer 11 provided in the polarizing plate 10, and defects present in the first intermediate M1 (polarizing plate 10) are detected based on this cross-Nicol image. It is also possible to adopt a reflection inspection in which a reflection image is generated by light reflected by the first intermediate M1, and defects present in the first intermediate M1 (polarizing plate 10) are detected based on this reflection image. Furthermore, it is also possible to perform any combination of the transmission inspection, the cross-Nicol inspection, and the reflection inspection.

After being inspected by the inspection device 20, the first intermediate M1 is transported toward the lamination roller R3. The lamination roller R3 then re-laminates the separator 4 to the first intermediate M1. That is, the separator 4 is laminated to the polarizing plate 10 constituting the first intermediate M1 via the adhesive layer 3 constituting the first intermediate M1. This produces the second intermediate M2, which is then wound up by the winding roller R4. The separator 4 of the second intermediate M2 unwound from the unwound roller R1 and the separator 4 of the second intermediate M2 wound up by the winding roller R4 are both the same separator 4.

[Surface protection film attachment step ST5]
The surface protection film bonding step ST5 is performed before the first separator peeling/bonding step ST6. In the surface protection film bonding step ST5, a long strip-shaped surface protection film 5 is bonded to the long strip-shaped second intermediate M2. Specifically, the long strip-shaped surface protection film 5 is bonded to the surface of the polarizing plate 10 constituting the second intermediate M2 opposite to the side to which the separator 4 is bonded. In this way, a long strip-shaped optical laminate 100 is manufactured.

[First separator peeling/laminating step ST6]
In the first separator peeling/bonding process ST6, the long strip separator 4 is peeled from the adhesive layer 3 of the long strip optical laminate 100 (only the separator 4 is peeled off, leaving the adhesive layer 3 interposed between the separator 4 and the polarizing plate 10 on the polarizing plate 10 side), and then the long strip separator 4 is bonded to the polarizing plate 10 via the adhesive layer 3, thereby returning the long strip optical laminate 100 to its original state.

4 is a side view (as viewed from a horizontal direction perpendicular to the conveying direction of each film) showing a schematic configuration example of an apparatus for performing the first separator peeling/laminating step ST6. The arrows shown in FIG. 4 indicate the conveying direction of each film.
In the first separator peeling/laminating step ST6, the optical laminate 100 manufactured in the surface protective film laminating step ST5 as described above is wound around a pay-out roller R5 shown in Fig. 4 and disposed on the most upstream side of the apparatus (the most upstream side in the conveying direction of the optical laminate 100). Then, the optical laminate 100 paid out from the pay-out roller R5 is conveyed toward a peeling roller R6. In the peeling roller R6, the separator 4 is peeled off from the optical laminate 100, and the peeled separator 4 is conveyed toward a laminating roller R7.

On the other hand, the third intermediate M3, which is a laminate of the surface protective film 5, the polarizing plate 10, and the adhesive layer 3 obtained by peeling the separator 4 from the optical laminate 100 by the peeling roller R6, is also transported toward the laminating roller R7. Then, the separator 4 is again laminated to the third intermediate M3 by the laminating roller R7. That is, the separator 4 is laminated to the polarizing plate 10 constituting the third intermediate M3 via the adhesive layer 3 constituting the third intermediate M3. In this way, the optical laminate 100 is manufactured and taken up by the winding roller R8. The separator 4 of the optical laminate 100 unwound from the unwinding roller R5 and the separator 4 of the optical laminate 100 taken up by the winding roller R8 are the same separator 4.
The manufacturing method according to the present embodiment includes the first separator peeling/laminating step ST6, whereby the separator 4 is peeled off and laminated. In other words, even if the separator 4 to be laminated is the same as the separator 4 to be peeled off, the separator 4 is laminated to the polarizing plate 10 in a state in which the irregularities of the separator 4 are stretched out. Since the first separator peeling/laminating step ST6 is performed after the surface protective film laminating step ST5, the separator 4 in a state in which the irregularities are stretched out is laminated to the highly rigid laminate (third intermediate body M3), and curling can be suppressed even if a force acts to return the separator 4 to its contracted state.
In addition, the manufacturing method according to the present embodiment includes the inspection step ST4 as a second separator peeling/bonding step, and thus the separator 4 is peeled off and bonded not only after the surface protective film bonding step ST5 but also before the surface protective film bonding step ST5. This makes it possible to further suppress curling.

In this embodiment, in the first separator peeling/laminating step ST6, the time from peeling the long strip separator 4 to laminating the long strip separator 4 is within 1 minute, preferably within 45 seconds, and more preferably within 30 seconds. Specifically, as shown in Fig. 4, when the length of the transport path of the optical laminate 100 from the peeling roller R6 to the laminating roller R7 is L and the transport speed is V, the length L of the transport path and the transport speed V are set so that L/V ≦ 1 minute (preferably 45 seconds, more preferably 30 seconds).
As described above, in this embodiment, the time from peeling off the separator 4 to bonding the separator 4, in other words, the time during which the adhesive layer 3 is exposed, is short, so that even if the humidity in the first separator peeling/bonding process ST6 changes due to, for example, seasonal influences or daytime or nighttime influences, it is possible to suppress variations in curl that occur when the polarizing plate 10 absorbs moisture in the atmosphere from the adhesive layer 3 side and swells.

Hereinafter, the lamination of the third intermediate M3 and the separator 4 by the laminating roller R7 will be described in more detail.
5 is an explanatory diagram for explaining lamination of the third intermediate body M3 and the separator 4 by the lamination roller R7. As shown in FIG. 5, the lamination roller R7 is composed of a pair of opposing first and second rollers R71 and R72. The first roller R71 is a roller that contacts the separator 4 and transports the separator 4 between the first roller R71 and the second roller R72. The surface of the first roller R71 is made of metal (e.g., iron). The second roller R72 is a roller that contacts the third intermediate body M3 and transports the third intermediate body M3 between the first roller R71 and the second roller R72. The surface of the second roller R72 is made of resin (e.g., rubber).

As shown in FIG. 5, a straight line (virtual line) passing through the rotation center C1 of the first roller R71 and the rotation center C2 of the second roller R72 is defined as a straight line CL. A vector (virtual vector) perpendicular to the straight line CL and directed toward the exit side (right side of FIG. 5) of the lamination roller R7 is defined as a vector VC. At this time, the approach angle α of the separator 4 to the lamination roller R7 means the angle between the vector VC and the vector indicating the traveling direction of the separator 4 until it contacts the lamination roller R7. In addition, the approach angle β of the third intermediate M3 to the lamination roller R7 (corresponding to the approach angle of the polarizing plate 10 to the lamination roller R7) means the angle between the vector VC and the vector indicating the traveling direction of the third intermediate M3 until it contacts the lamination roller R7 (corresponding to the traveling direction of the polarizing plate 10).
In this embodiment, both the approach angle α and the approach angle β are set to less than 90°. In FIG. 4, for convenience, α=90° and β=0° are illustrated, but in reality, α<90° and β<90°, preferably 10°<α<80°, and more preferably 20°<α<50°. Also, preferably 0°<β<80°, and more preferably 0°<β<75°. By increasing the approach angle α, the transportability of the third intermediate M3 (polarizing plate 10) is improved.

According to the findings of the inventors, when the approach angle α of the separator 4 to the lamination roller R7 is large (90° or more), the curl in the TD direction and the negative curl (the curl in which the side where the separator 4 is located is concave) becomes large, and when the approach angle β of the third intermediate M3 (polarizing plate 10) to the lamination roller R7 is large (90° or more), the curl in the TD direction and the positive curl (the curl in which the side where the separator 4 is located is convex) becomes large.
Therefore, by making α<90° and β<90° as described above, curling can be further suppressed.

In the present embodiment, the case where the peeled separator 4 and the separator 4 to be bonded in the first separator peeling/laminating process ST6 are the same separator 4 have been described as an example, but the present invention is not limited to this. In the first separator peeling/laminating process ST6, the peeled separator 4 and the separator 4 to be bonded may be different separators 4. Below, a modified example of the first separator peeling/laminating process ST6 in which the peeled separator 4 and the separator 4 to be bonded are different will be described.

In a modified example of the first separator peeling/laminating process ST6, a new separator 4 different from the peeled separator 4 is laminated to the polarizing plate 10 via the adhesive layer 3. Hereinafter, the separator 4 to be peeled (the separator 4 laminated in the inspection process ST4) will be referred to as "separator 4a" and the new separator 4 laminated in the modified example of the first separator peeling/laminating process ST6 will be referred to as "separator 4b" to distinguish between the two.

6 is a side view (as viewed from a horizontal direction perpendicular to the conveying direction of each film) showing a schematic configuration example of an apparatus for performing a modified example of the first separator peeling/laminating step ST6. The arrows shown in FIG. 6 indicate the conveying direction of each film.
In a modified example of the first separator peeling/laminating step ST6, the optical laminate 100 manufactured in the surface protective film laminating step ST5 as described above is wound around a pay-out roller R9 shown in Fig. 6 and disposed on the most upstream side of the device (the most upstream side in the transport direction of the optical laminate 100). Then, the optical laminate 100 paid out from the pay-out roller R9 is transported toward a peeling roller R10. At the peeling roller R10, the separator 4a is peeled off from the optical laminate 100, and the peeled separator 4a is taken up by a take-up roller R11.

On the other hand, the third intermediate M3, which is a laminate of the surface protective film 5, the polarizing plate 10, and the adhesive layer 3 obtained by peeling the separator 4a from the optical laminate 100 by the peeling roller R10, is transported toward the lamination roller R12. In addition, a new separator 4b (i.e., a separator that is not heated to form the adhesive layer 3 and is therefore unlikely to cause unevenness) wound around the pay-out roller R13 is prepared, and this separator 4b is unwound from the pay-out roller R13 and transported toward the lamination roller R12. Then, the separator 4b is bonded to the third intermediate M3 by the lamination roller R12. That is, the separator 4b is bonded to the polarizing plate 10 constituting the third intermediate M3 via the adhesive layer 3 constituting the third intermediate M3. In this way, the optical laminate 100 is manufactured and taken up by the winding roller R14. The separator 4 of the optical laminate 100 fed from the feed roller R9 is separator 4a, whereas the separator 4 of the optical laminate 100 taken up by the take-up roller R14 is separator 4b.
According to the modified example of the first separator peeling/laminating step ST6, a new separator 4b different from the peeled separator 4a is laminated, so that curling can be further suppressed.
In this modification, the elastic modulus (elastic modulus in the TD direction) of the new separator 4b to be bonded to the polarizing plate 10 in the modification of the first separator peeling/laminating step ST6 is, for example, 6000 [N/ ^mm2 ] or more, while the elastic modulus (elastic modulus in the TD direction) of the separator laminating step ST3 after the pressure-sensitive adhesive layer forming step (i.e., after heating) is, for example, less than 6000 [N/ ^mm2 ], and the elastic modulus of the separator 4b is higher than that of the separator 4a. If the elastic modulus of the separator 4b is higher than that of the separator 4a, the new separator 4b bonded (replaced) in the modification of the first separator peeling/laminating step ST6 is less likely to shrink, and curling can be further suppressed. The upper limit of the elastic modulus (transverse direction elastic modulus) of separator 4b is not particularly limited, but is, for example, 7000 [N/ ^mm2 ] or less, and preferably 6500 [N/ ^mm2 ] or less. The lower limit of the elastic modulus (transverse direction elastic modulus) of separator 4a is not particularly limited, but is, for example, 5000 [N/ ^mm2 ] or more, and preferably 5500 [N/ ^mm2 ] or more.
The elastic modulus can be measured, for example, by using a tensile tester "Autograph" manufactured by Shimadzu Corporation. Specifically, a sample having a width (dimension in MD) of 10 mm and a length (dimension in TD) of 100 mm is cut out from each of the separators 4a and 4b alone, and the sample is set in the autograph and pulled in the TD direction at a speed of 50 mm/min. The elastic modulus can be calculated based on the force [N] applied to stretch the sample by a predetermined amount.

4 and 5, in the modified first separator peeling/laminating step ST6, the time from peeling the separator 4a with the peeling roller R10 to laminating the separator 4b with the laminating roller R12 is within 1 minute, preferably within 45 seconds, and more preferably within 30 seconds. Also, in the modified first separator peeling/laminating step ST6, the surface of the roller that contacts the separator 4b and transports the separator 4b between the pair of rollers is made of metal (e.g., iron) among the pair of opposing rollers that make up the laminating roller R12. The surface of the roller that contacts the third intermediate M3 and transports the third intermediate M3 between the pair of rollers is made of resin (e.g., rubber). Furthermore, even in the modified example of the first separator peeling/laminating step ST6, both the approach angle α of the separator 4b to the laminating roller R12 and the approach angle β of the third intermediate M3 (polarizing plate 10) to the laminating roller R12 are set to less than 90°. As a result, even in the modified example of the first separator peeling/laminating step ST6, curling can be further suppressed. The approach angle α of the separator 4b to the laminating roller R12 and the approach angle β of the third intermediate M3 (polarizing plate 10) to the laminating roller R12 are preferably 10°<α<80°, and more preferably 20°<α<50°. Also, preferably 0°<β<80°, and more preferably 0°<β<75°. By increasing the approach angle α, the transportability of the third intermediate M3 (polarizing plate 10) is improved.

3, the time from peeling the separator 4 with the peeling roller R2 to laminating the separator 4 with the laminating roller R3 is within 1 minute, preferably within 45 seconds, more preferably within 30 seconds, as in the first separator peeling and laminating step ST6 described with reference to Figs. 4 and 5. Also, in the inspection step ST4, the surface of the roller that contacts the separator 4 and transports the separator 4 between the pair of rollers, among the pair of opposing rollers that constitute the laminating roller R3, is made of metal (e.g., iron), as in the first separator peeling and laminating step ST6. The surface of the roller that contacts the first intermediate M1 and transports the first intermediate M1 between the pair of rollers is made of resin (e.g., rubber). Also, in the inspection process ST4, similarly to the first separator peeling/laminating process ST6, both the approach angle α of the separator 4 to the laminating roller R3 and the approach angle β of the first intermediate M1 (polarizing plate 10) to the laminating roller R3 are set to less than 90°. As a result, curling can be further suppressed in the inspection process ST4. Furthermore, in the inspection process ST4, similarly to the modified example of the first separator peeling/laminating process ST6 described with reference to FIG. 6, it is also possible to adopt a mode in which a new separator 4 different from the peeled separator 4 is laminated to the polarizing plate 10 after inspection. The approach angle α of the separator 4 to the laminating roller R3 and the approach angle β of the first intermediate M1 (polarizing plate 10) to the laminating roller R3 are preferably 10°<α<80°, more preferably 20°<α<50°. Also, preferably 0°<β<80°, more preferably 0°<β<75°. Increasing the approach angle α improves the transportability of the first intermediate M1 (polarizing plate 10).

The manufacturing method according to this embodiment described above makes it possible to effectively suppress curling without changing the materials of the components of the optical laminate 100 that have been conventionally used.

In this embodiment, the inspection process ST4 also serves as the second separator peeling and laminating process, but the present invention is not limited to this. It is also possible to perform the inspection process ST4 and the second separator peeling and laminating process separately. Alternatively, it is also possible to adopt a mode in which no inspection is performed in the inspection process ST4 (i.e., the second separator peeling and laminating process is simply performed to peel and laminate the separator 4). Alternatively, it is also possible to adopt a mode in which the inspection process ST4 itself is not performed (i.e., the separator 4 is peeled and laminated only in the first separator peeling and laminating process ST6).

In addition, in this embodiment, the polarizing plate 10 is a laminate of the polarizing film 1 and the retardation film 2, but the present invention is not limited to this. It is also possible to adopt an embodiment in which the polarizing plate 10 is a laminate of the polarizing film 1, the retardation film 2, and other components, an embodiment in which the retardation film 2 is not present and the polarizing plate 10 is a laminate of the polarizing film 1 and other components, or an embodiment in which only the polarizing film 1 is present in the polarizing plate 10.

Below, we will explain an example of the results of evaluating the curl of the optical laminate 100 manufactured by the manufacturing method (example) of this embodiment shown in Figure 2, and an example of the results of evaluating the curl of the optical laminate manufactured by the conventional manufacturing method (comparison example) shown in Figure 8.
The optical laminates 100 produced in the examples and comparative examples all had a configuration in which layers were laminated in the following order.
(1) Surface protection film 5 (substrate: PET, thickness 38 μm, adhesive layer: acrylic adhesive, thickness 10 μm)
(2) Cycloolefin-based protective film 12 (total thickness 32 μm) with hard coat layer (thickness 7 μm)
(3) Adhesive (4) Polyvinyl alcohol-based polarizer 11 (thickness 12 μm)
(5) Adhesive (6) Triacetyl cellulose-based protective film 13 (thickness 25 μm)
(7) Adhesive (8) Polymerizable liquid crystal type half-wave plate 2 (thickness 2.5 μm)
(9) Acrylic pressure-sensitive adhesive layer 3 (thickness: 20 μm)
(10) Separator 4 (PET, thickness 38 μm)
In addition, the optical laminate 100 manufactured in the embodiment was manufactured by bonding the same separator 4 as the peeled separator 4 to the polarizing plate 10 after inspection in the first separator peeling/bonding process ST6 and the inspection process ST4 (the separator 4 was not replaced in the first separator peeling/bonding process ST6 and the inspection process ST4).

FIG. 7 is an explanatory diagram for explaining a method for evaluating curl.
As shown in FIG. 7A, in the embodiment, a rectangular optical laminate 100S having a product size (148 mm long x 70 mm wide) was cut out along the TD direction of a long optical laminate 100. In FIG. 7A, three optical laminates 100S are shown for convenience, but in reality, 10 optical laminates 100S were cut out along the TD direction of one optical laminate 100. This was performed for a plurality of optical laminates 100, and a total of 500 optical laminates 100S were obtained. Then, curl was evaluated for 100 randomly selected from the 500 optical laminates 100S. Note that, as shown in FIG. 7B, when cutting out the optical laminate 100S, it was cut out obliquely so that the MD direction of the optical laminate 100 (corresponding to the direction of the absorption axis of the polarizer 11) was 45° to the long side and short side of the optical laminate 100S.

7(c), when evaluating curl, the optical laminate 100S was placed on a flat mounting table 30 so that the underside of the optical laminate 100S was convex (so that the warping of the four corners of the optical laminate 100S was directed vertically upward), and the vertical distance H from the upper surface of the mounting table 30 to each of the four corners of the optical laminate 100S was measured. The distance H was measured by setting up a scale extending vertically near the corners of the optical laminate 100S and visually reading the graduations of this scale.
When the optical laminate 100S was placed on the mounting table 30 so that the bottom side thereof was convex, a case in which the side of the optical laminate 100S where the separator 4 was located was on the bottom (the side where the surface protective film 5 was on the top) was considered to be a positive curl, and the measured distance H was calculated as the curl value as it was. On the other hand, when the optical laminate 100S was placed on the mounting table 30 so that the bottom side thereof was convex, a case in which the side of the optical laminate 100S where the separator 4 was located was on the top (the side where the surface protective film 5 was on the bottom) was considered to be a negative curl, and the measured distance H was multiplied by -1 to calculate the curl value.

Next, the separator 4 was peeled off from the optical laminate 100S to leave the third intermediate body M3. The curl values of the four corners of the third intermediate body M3 were then calculated using the same procedure as above.

If the curl values of the four corners of the optical laminate 100S and the curl values of the four corners of the third intermediate M3 all satisfied the condition -5 mm≦curl value≦5 mm, the product was deemed to have passed, and if they did not, the product was deemed to have failed.
For the comparative examples, the curl value was calculated in the same manner as in the examples described above, and a pass or fail judgment was made.

表１に示すように、比較例では、１００枚の光学積層体のうち４４枚が合格（合格率４４％）であったのに対し、実施例では、１００枚の光学積層体のうち９５枚が合格（合格率９５％）であり、カールが抑制されることが分かった。 Table 1 shows the evaluation results of curl for the Examples and Comparative Examples.

As shown in Table 1, in the comparative example, 44 out of 100 optical laminates passed (pass rate 44%), whereas in the example, 95 out of 100 optical laminates passed (pass rate 95%), demonstrating that curling was suppressed.

REFERENCE SIGNS LIST 1: Polarizing film 10: Polarizing plate 11: Polarizer 12, 13: Protective film 2: Retardation film 3: Pressure-sensitive adhesive layer 4: Separator 5: Surface protective film 100, 100S: Optical laminate ST1: Polarizing film manufacturing process ST2: Retardation film bonding process ST3: Separator bonding process ST4: Inspection process (second separator peeling/bonding process)
ST5: Surface protection film attachment step ST6: First separator peeling and attachment step

Claims (7)

a separator lamination step of laminating a long strip-shaped separator to a long strip-shaped polarizing plate via a pressure-sensitive adhesive layer formed on the separator;
a second separator peeling/sticking step of peeling the long strip separator from the pressure-sensitive adhesive layer after the separator sticking step, and then sticking the long strip separator to the polarizing plate via the pressure-sensitive adhesive layer;
a surface protection film laminating step of laminating a long strip-shaped surface protection film to a surface of the polarizing plate opposite to the surface to which the separator is laminated , after the second separator peeling/laminating step;
and a first separator peeling/sticking step of peeling a long strip-shaped separator from the pressure-sensitive adhesive layer after the surface protective film sticking step, and then sticking the long strip-shaped separator to the polarizing plate via the pressure-sensitive adhesive layer.
A method for producing an optical laminate. The separator laminating step includes a pressure-sensitive adhesive layer forming step of applying a pressure-sensitive adhesive to a long strip-shaped separator and heating and curing the applied pressure-sensitive adhesive to form the pressure-sensitive adhesive layer.
A method for producing the optical laminate according to claim 1 . The second separator peeling/bonding step also serves as an inspection step of inspecting the polarizing plate after peeling off the long strip-shaped separator.
A method for producing the optical laminate according to claim 1 or 2. In the first separator peeling/laminating step, the time from peeling the long strip separator to laminating the long strip separator is within 1 minute.
A method for producing the optical laminate according to claim 1 . In the first separator peeling/laminating step, a long strip-shaped separator and the polarizing plate are laminated together by a laminating roller;
an approach angle of the separator to the lamination roller being less than 90°, and an approach angle of the polarizing plate to the lamination roller being less than 90°;
A method for producing the optical laminate according to claim 1 . the lamination roller includes a first roller that contacts the separator and a second roller that contacts the polarizing plate,
one of the first roller and the second roller has a surface made of resin and the other has a surface made of metal;
A method for producing the optical laminate according to claim 5 . the first roller has a surface made of metal;
The second roller has a surface made of resin.
A method for producing the optical laminate according to claim 6.

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