JP7621081B2 - Method for producing optical laminate - Google Patents

Description

The present invention relates to a method for producing an optical laminate by laminating a long, laterally stretched first optical film and a long, laterally stretched second optical film with nip rollers while transporting them in the longitudinal direction. In particular, the present invention relates to a method for producing an optical laminate that can suppress the occurrence of wrinkles and surface scratches in the optical laminate and can suppress curling of the optical laminate after cutting to product size.

2. Description of the Related Art Conventionally, there has been known a method for producing an optical laminate by laminating a long first optical film and a long second optical film with nip rollers while transporting them in the longitudinal direction (see, for example, Patent Document 1).
In a manufacturing method of the optical laminate (laminate 4, polarizing plate in Patent Document 1) as described above, guide rollers (adjustment rolls 21, 22 in Patent Document 1) that guide the first optical film and the second optical film toward the nip roller are arranged upstream of the nip roller (lamination rolls 11, 12 in Patent Document 1) in the transport direction of the first optical film (transparent film 1 in Patent Document 1) and the second optical film (polarizing film 2 in Patent Document 1). In this case, the rotation axis of the guide roller and the rotation axis of the nip roller are generally parallel to each other.

Here, for example, when the first optical film is a protective film having a base layer formed from polyethylene terephthalate, and the first optical film is a film that has been stretched laterally (stretched in a direction perpendicular to the longitudinal direction), slack may occur at one end in the width direction of the first optical film. That is, slack may occur at one end that is longer in length after the first optical film is stretched laterally, as compared with the other end. For example, when the second optical film is a separator formed from polyethylene terephthalate, and the second optical film is a film that has been stretched laterally, slack may occur at one end in the width direction of the second optical film.

According to the investigations conducted by the present inventors, when slack is present at the widthwise ends of the first optical film and/or the second optical film as described above, if these films are guided by a guide roller having a rotation axis parallel to the rotation axis of the nip roller and laminated together by the nip roller, wrinkles and surface scratches (scratches) may occur in the optical laminate obtained by lamination due to the influence of the slack. In addition, curling (warping of the ends) may occur in the optical laminate after cutting to the product size due to the influence of the slack.

JP 2014-122967 A

The present invention has been made to solve the problems of the conventional technology as described above, and aims to provide a method for manufacturing an optical laminate that can suppress the occurrence of wrinkles and surface scratches on the optical laminate, and can suppress curling of the optical laminate after cutting to product size.

In order to solve the above problem, the inventors first considered adjusting the posture of the guide roller so that the rotation axis of the guide roller is inclined from a state in which it is parallel to the rotation axis of the nip roller toward the end of the first optical film and/or second optical film in the width direction on the side where slack occurs, toward the direction in which the guide roller approaches the end. This is because it was thought that by adjusting the posture of the guide roller as described above, the path length of the end on the side where slack occurs of the first optical film and/or second optical film from the guide roller to the nip roller becomes longer than the path length of the end on the opposite side, and therefore, when the first optical film and the second optical film are laminated together by the nip roller, the effect of slack occurring at the longer end is mitigated by the longer path length.

It was found that by adjusting the position of the guide roller as described above, it is possible to suppress the occurrence of wrinkles and surface scratches in the optical laminate.
However, it has also been found that curling occurring in the optical laminate after cutting into the product size cannot be sufficiently suppressed.

In light of the above considerations, the inventors conducted further intensive research and, as a result, contrary to the above considerations, considered adjusting the posture of the guide roller so that the rotation axis of the guide roller is inclined from a state in which it is parallel to the rotation axis of the nip roller toward the direction in which the guide roller moves away from the end of one of the widthwise ends of the first optical film and/or the second optical film on which slack has occurred.
The reason for this is that by making the above adjustments, the path length of the end portion opposite the side where slack occurs of the first optical film and/or second optical film from the guide roller to the nip roller is increased, so that the length of the opposite end portion approaches the length of the end portion on the side where slack occurs, thereby mitigating the effects of slackness.

It was found that by adjusting the position of the guide roller as described above, it is possible to suppress the occurrence of wrinkles and surface scratches in the optical laminate.
Moreover, it was found that curling that occurs in the optical laminate after cutting into the product size can also be suppressed.

The present invention has been completed based on the above-mentioned findings of the present inventors.
That is, in order to solve the above-mentioned problems, the present invention provides a method for producing an optical laminate by bonding a long first optical film that has been laterally stretched and a long second optical film that has been laterally stretched together using a nip roller while transporting them in the longitudinal direction, wherein a guide roller that guides the first optical film and/or the second optical film toward the nip roller is disposed upstream of the nip roller in the transport direction of the first optical film and/or the second optical film, and the posture of the guide roller is adjusted so that the rotation axis of the guide roller is inclined from a state in which it is parallel to the rotation axis of the nip roller toward a direction in which the guide roller moves away from one of both widthwise end portions of the first optical film and/or the second optical film where slack occurs.

In the present invention, "a state in which the rotation axis of the guide roller is inclined in a direction in which the guide roller moves away from the end portion on the side where slack is occurring, of both widthwise end portions of the first optical film and/or the second optical film" is not limited to a state in which the end portion of the rotation axis of the guide roller located on the end portion on the side where slack is occurring of the first optical film and/or the second optical film has moved in a direction away from the end portion on the side where slack is occurring of the first optical film and/or the second optical film, but is a concept including a state in which the end portion of the rotation axis of the guide roller located on the end portion opposite the end portion on the side where slack is occurring of the first optical film and/or the second optical film has moved in a direction approaching the end portion opposite the end portion on the side where slack is occurring of the first optical film and/or the second optical film. The concept also includes a combination of a state in which the end of the guide roller rotation shaft located at the end side on the side where slack in the first optical film and/or second optical film occurs has moved in a direction away from the end side on the side where slack in the first optical film and/or second optical film occurs, and a state in which the end of the guide roller rotation shaft located at the end side opposite the end side on the side where slack in the first optical film and/or second optical film occurs has moved in a direction approaching the end side opposite the end side on the side where slack in the first optical film and/or second optical film occurs. In other words, it refers to a state in which, of both ends of the rotation shaft of the guide roller, the end of the guide roller rotation shaft located at the end side on the side on which slack in the first optical film and/or second optical film occurs has moved in a direction relatively away from the end side on the side on which slack in the first optical film and/or second optical film occurs.
In the present invention, the term "transversely stretched" means stretched in a direction perpendicular to the longitudinal direction. The term "transversely stretched" is not limited to the case where only transverse stretching is performed, but is a concept including the case where at least transverse stretching is performed, such as the case where longitudinal stretching is also performed (i.e., longitudinal and transverse stretching).

According to the present invention, a guide roller that guides the first optical film and/or the second optical film toward the nip roller is disposed upstream of the nip roller in the transport direction of the first optical film and/or the second optical film. That is, in a first embodiment, a guide roller that guides the first optical film toward the nip roller (hereinafter, appropriately referred to as the "first guide roller") is disposed upstream of the first optical film in the transport direction. In a second embodiment, a guide roller that guides the second optical film toward the nip roller (hereinafter, appropriately referred to as the "second guide roller") is disposed upstream of the second optical film in the transport direction. Furthermore, in a third embodiment, guide rollers (first guide roller and second guide roller) that guide the first optical film and the second optical film toward the nip roller, respectively, are disposed upstream of the first optical film and the second optical film in the transport direction.
According to the present invention, the posture of the guide roller is adjusted so that the rotation axis of the guide roller is inclined from a state in which it is parallel to the rotation axis of the nip roller toward a direction in which the guide roller moves away from the end portion of the first optical film and/or the second optical film in the width direction on the side where slack occurs. That is, in the first aspect, the posture of the first guide roller is adjusted so that the rotation axis of the first guide roller is inclined toward a direction in which the first guide roller moves away from the end portion of the first optical film in the width direction on the side where slack occurs. In the second aspect, the posture of the second guide roller is adjusted so that the rotation axis of the second guide roller is inclined toward a direction in which the second guide roller moves away from the end portion of the second optical film in the width direction on the side where slack occurs. Furthermore, in the above-mentioned third aspect, the posture of the first guide roller is adjusted so that the rotation axis of the first guide roller is inclined in the direction in which the first guide roller moves away from the end of the first optical film on the side where slack occurs, and the posture of the second guide roller is adjusted so that the rotation axis of the second guide roller is inclined in the direction in which the second guide roller moves away from the end of the second optical film on the side where slack occurs,.
According to the present invention, as found by the present inventors, it is possible to suppress the occurrence of wrinkles and surface defects in the optical laminate, and also possible to suppress curling of the optical laminate after cutting into a product size.

In the present invention, when both the first optical film and the second optical film have an end portion on the side where slack occurs, it is preferable to bond the first optical film and the second optical film together with the nip roller so that the end portion on the side where slack occurs of the first optical film and the end portion on the side where slack occurs of the second optical film are laminated.

The above preferred method can further suppress the occurrence of wrinkles in the optical laminate.

The present invention is preferably used, for example, in a case where the first optical film is a protective film having a base layer and a pressure-sensitive adhesive layer, the second optical film is a separator, and the pressure-sensitive adhesive layer of the first optical film is bonded to the second optical film.
The optical laminate obtained as described above is used as a protective cover for the panel, for example, by attaching the pressure-sensitive adhesive layer to the front surface of an OLED (organic electroluminescence) panel or a liquid crystal panel after peeling off the separator.

The present invention makes it possible to prevent wrinkles and surface scratches on the optical laminate, and also to prevent curling of the optical laminate after cutting to product size.

FIG. 1 is a diagram for explaining a schematic configuration of a manufacturing apparatus for carrying out a conventional method for manufacturing an optical laminate. FIG. 2 is a cross-sectional view showing a schematic configuration of an optical laminate. FIG. 1 is a diagram for illustrating a schematic configuration of a manufacturing apparatus for carrying out a method for manufacturing an optical laminate according to a first embodiment. FIG. 13 is a diagram for illustrating a schematic configuration of a manufacturing apparatus for carrying out a method for manufacturing an optical laminate according to a second embodiment. FIG. 13 is a diagram for illustrating a schematic configuration of a manufacturing apparatus for carrying out a method for manufacturing an optical laminate according to a third embodiment. FIG. 11 is a diagram for explaining a method for measuring the amount of slack. FIG. 2 is a diagram for illustrating a schematic configuration of a manufacturing apparatus for carrying out a manufacturing method for an optical laminate S according to a reference example. FIG. 2 is a diagram for illustrating a method for evaluating curl of an optical laminate. 1 shows the evaluation results of the optical laminates produced by the production method according to Comparative Example 1 and the production method according to the reference example. 1 shows the evaluation results of the optical laminates produced by the production method according to Comparative Example 1 and the production method according to Example 1. 1 shows the evaluation results of the optical laminates produced by the production method according to Comparative Example 2 and the production method according to Example 2. 1 shows the evaluation results of the optical laminates produced by the production method according to Comparative Example 3 and the production method according to Example 3. The evaluation results of the optical laminate S produced by the production method according to Example 4 are shown.

The method for producing an optical laminate according to the first to third embodiments of the present invention will be described below with reference to the attached drawings.

<Conventional method for producing optical laminate>
Before describing the method for producing an optical laminate according to this embodiment (hereinafter, the first to third embodiments are collectively referred to as this embodiment), a conventional method for producing an optical laminate will first be described.
FIG. 1 is a diagram for explaining the schematic configuration of a manufacturing apparatus for carrying out a conventional method for manufacturing an optical laminate. FIG. 1(a) is a perspective view showing the schematic configuration of the manufacturing apparatus. FIG. 1(b) is a plan view showing the schematic configuration of the manufacturing apparatus. In FIG. 1, X indicates the width direction of the optical laminate S, Y indicates the longitudinal direction of the optical laminate S (the conveying direction of the optical laminate S), and Z indicates the vertical direction. In FIG. 1, OS indicates the operation side where various operations are performed, and DS indicates the drive side where the main drive source is provided. In FIG. 1(b), the first optical film F1, the second optical film F2, and the optical laminate S are omitted. The meanings of X, Y, X, OS, and DS are the same in FIGS. 2 to 7 described later.

[Optical laminate S]
First, the configuration of the optical laminate S manufactured by a conventional manufacturing apparatus will be described. The optical laminate S manufactured by the manufacturing apparatus of this embodiment and the manufacturing apparatus according to the reference example described later has the same configuration.
FIG. 2 is a cross-sectional view (XZ cross-sectional view) showing a schematic configuration of the optical laminate S.
2, the optical laminate S has a configuration in which a first optical film F1, which is a protective film, and a second optical film F2, which is a separator, are laminated together. The first optical film F1 has a base layer F11 and a pressure-sensitive adhesive layer F12, and the pressure-sensitive adhesive layer F12 is bonded to the second optical film F2, thereby laminating the first optical film F1 and the second optical film F2.

(Base layer F11 of first optical film F1)
The base material layer F11 may be composed of a single layer or may be composed of multiple layers. The base material layer F11 is stretched laterally. Specifically, the base material layer 11 is stretched longitudinally and transversely (biaxially stretched). That is, the base material layer 11 is stretched in the longitudinal direction and the width direction.

The thickness of the base layer F11 can be set to any appropriate thickness depending on the application. The thickness of the base layer F11 is preferably 20 μm to 150 μm, more preferably 25 μm to 125 μm, even more preferably 30 μm to 100 μm, and particularly preferably 35 μm to 75 μm.

The base material layer F11 is made of plastic. The base material layer F11 may be made of one type of plastic, or may be made of two or more types of plastic.
Examples of the plastics include polyester resins, polyamide resins, and polyolefin resins. Examples of the polyester resins include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Examples of the polyolefin resins include homopolymers of olefin monomers and copolymers of olefin monomers. Specific examples of the polyolefin resins include homopolypropylene; propylene copolymers such as block, random, and graft copolymers with an ethylene component as a copolymerization component; reactor TPO; ethylene polymers such as low density, high density, linear low density, and ultra-low density; ethylene copolymers such as ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, ethylene-methyl acrylate copolymers, ethylene-ethyl acrylate copolymers, ethylene-butyl acrylate copolymers, ethylene-methacrylic acid copolymers, and ethylene-methyl methacrylate copolymers; and the like.

The substrate layer F11 may contain any suitable additive as necessary. Examples of additives that may be contained in the substrate layer F11 include antioxidants, UV absorbers, light stabilizers, antistatic agents, fillers, and pigments. The type, number, and amount of additives that may be contained in the substrate layer F11 may be appropriately set according to the purpose. Since the material of the substrate layer F11 is plastic, it is preferable to contain some of the above additives for the purpose of preventing deterioration, etc. From the viewpoint of improving weather resistance, etc., particularly preferred additives include antioxidants, UV absorbers, light stabilizers, and fillers.

Any suitable antioxidant can be used as the antioxidant. Examples of such antioxidants include phenol-based antioxidants, phosphorus-based processing heat stabilizers, lactone-based processing heat stabilizers, sulfur-based heat stabilizers, and phenol-phosphorus-based antioxidants. The content of the antioxidant is preferably 1% by weight or less, more preferably 0.5% by weight or less, and even more preferably 0.01% by weight to 0.2% by weight, based on the base resin of the substrate layer F11 (if the substrate layer F11 is a blend, the blend is the base resin).

Any suitable ultraviolet absorber can be used as the ultraviolet absorber. Examples of such ultraviolet absorbers include benzotriazole-based ultraviolet absorbers, triazine-based ultraviolet absorbers, and benzophenone-based ultraviolet absorbers. The content of the ultraviolet absorber is preferably 2% by weight or less, more preferably 1% by weight or less, and even more preferably 0.01% by weight to 0.5% by weight, based on the base resin forming the substrate layer F11 (if the substrate layer F11 is a blend, the blend is the base resin).

Any suitable light stabilizer can be used as the light stabilizer. Examples of such light stabilizers include hindered amine light stabilizers and benzoate light stabilizers. The content of the light stabilizer is preferably 2% by weight or less, more preferably 1% by weight or less, and even more preferably 0.01% by weight to 0.5% by weight, based on the base resin forming the substrate layer F11 (if the substrate layer F11 is a blend, the blend is the base resin).

As the filler, any appropriate filler can be used. Examples of such fillers include inorganic fillers. Specific examples of inorganic fillers include carbon black, titanium oxide, and zinc oxide. The content of the filler is preferably 20% by weight or less, more preferably 10% by weight or less, and even more preferably 0.01% by weight to 10% by weight, based on the base resin forming the substrate layer F11 (when the substrate layer F11 is a blend, the blend is the base resin).

Furthermore, as additives, inorganic, low molecular weight and high molecular weight antistatic agents such as surfactants, inorganic salts, polyhydric alcohols, metal compounds and carbon are also preferred for the purpose of imparting antistatic properties. In particular, high molecular weight antistatic agents and carbon are preferred from the viewpoints of preventing contamination and maintaining adhesion.

(Pressure-sensitive adhesive layer F12 of first optical film F1)
The pressure-sensitive adhesive layer F12 may be composed of a single layer, or may be composed of multiple layers.

The thickness of the adhesive layer F12 can be set to any appropriate thickness depending on the application. The thickness of the adhesive layer F12 is preferably 5 μm to 50 μm, more preferably 6 μm to 40 μm, even more preferably 7 μm to 30 μm, and particularly preferably 8 μm to 20 μm.

Any suitable adhesive layer can be used as the adhesive layer F12. The adhesive layer F12 contains at least one adhesive selected from, for example, an acrylic adhesive, a urethane adhesive, a silicone adhesive, a polyester adhesive, and a rubber adhesive.

The content of the adhesive in the adhesive layer F12 (e.g., at least one adhesive selected from an acrylic adhesive, a urethane adhesive, a silicone adhesive, a polyester adhesive, and a rubber adhesive) is preferably 96% by weight to 100% by weight, more preferably 97% by weight to 100% by weight, even more preferably 98% by weight to 100% by weight, and particularly preferably 99% by weight to 100% by weight. By adjusting the content of the adhesive in the adhesive layer F12 to within the above range, it is possible to obtain an adhesive layer F12 that has, for example, excellent adhesive transfer prevention properties and reworkability.

As the acrylic adhesive, any suitable acrylic adhesive can be used, such as the known acrylic adhesives described in JP 2013-241606 A, for example.

As the silicone-based adhesive, any suitable silicone-based adhesive can be used, such as the known silicone-based adhesives described in JP 2014-47280 A, for example.

As the polyester-based adhesive, any suitable polyester-based adhesive can be used, such as the known polyester-based adhesives described in JP 2013-216875 A, for example.

As the rubber-based adhesive, any suitable rubber-based adhesive can be used, such as the known rubber-based adhesives described in JP 2011-236358 A, for example.

As the urethane-based adhesive, any appropriate urethane-based adhesive, such as a known urethane-based adhesive, can be used.
As the urethane-based adhesive, it is particularly preferable to contain a polyurethane-based resin.
The content of the polyurethane resin in the urethane adhesive is preferably 40% by weight or more, more preferably 50% by weight or more, even more preferably 55% by weight or more, even more preferably 60% by weight, particularly preferably 65% by weight, and most preferably 70% by weight. The upper limit is preferably 99.999% by weight or less, more preferably 99.99% by weight or less, even more preferably 99.9% by weight or less, even more preferably 99% by weight or less, particularly preferably 95% by weight or less, and most preferably 90% by weight or less. By adjusting the content of the polyurethane resin in the urethane adhesive to within the above range, for example, a urethane adhesive having excellent antistatic properties, excellent adhesive residue prevention properties, and excellent reworkability can be obtained.

(Second Optical Film F2)
The second optical film F2 may be composed of a single layer or may be composed of multiple layers. The second optical film F2 is transversely stretched. Specifically, the second optical film F2 is longitudinally and transversely stretched (biaxially stretched). That is, the second optical film F2 is stretched in the longitudinal direction and the width direction.

The thickness of the second optical film F2 can be set to any appropriate thickness depending on the application. The thickness of the second optical film F2 is preferably 20 μm to 100 μm, more preferably 25 μm to 90 μm, even more preferably 30 μm to 80 μm, and particularly preferably 35 μm to 70 μm.

The second optical film F2 is a plastic film, and the surface of the adhesive layer F12 side is preferably coated with a release agent. The second optical film F2 may be formed from one type of plastic, or may be formed from two or more types of plastic. Specific examples of plastic films include polyethylene terephthalate films, polyethylene films, and polypropylene films. Specific examples of release agents include silicone-based release agents, fluorine-based release agents, and long-chain alkyl acrylate-based release agents.

[Conventional manufacturing equipment]
Next, the configuration of a conventional manufacturing apparatus will be described.
The conventional manufacturing apparatus is an apparatus for manufacturing the optical laminate S having the configuration described above.
As shown in FIG. 1, the conventional manufacturing apparatus includes a nip roller 10 and guide rollers (a first guide roller 20 and a second guide roller 30).

The nip roller 10 is composed of a pair of rollers 11, 12 arranged opposite to each other, and is a roller for sandwiching and laminating a long first optical film F1 and a long second optical film F2, which are respectively transported in the longitudinal direction, between the pair of rollers 11, 12. In the example shown in Fig. 1, the rollers 11, 12 are arranged opposite to each other in the vertical direction (Z direction).
The first guide roller 20 is positioned upstream of the nip roller 10 in the transport direction of the first optical film F1 (shown by the white arrow in Figure 1 (a)), and is a roller that guides the first optical film F1 toward the nip roller 10 (specifically, toward the space between the pair of rollers 11, 12).
The second guide roller 30 is positioned upstream of the nip roller 10 in the transport direction of the second optical film F2 (shown by the white arrow in Figure 1 (a)), and is a roller that guides the second optical film F2 toward the nip roller 10 (specifically, toward the space between the pair of rollers 11, 12).

As shown in FIG. 1B, in the conventional manufacturing apparatus, the rotation axis (center of rotation) 20L of the first guide roller 20 is parallel to the rotation axis (center of rotation) 10L of the nip roller 10. In other words, the rotation axis 10L of the nip roller 10 is parallel to the width direction (X direction) of the optical laminate S, and the rotation axis 20L of the first guide roller 20 is also parallel to the width direction (X direction) of the optical laminate S. Note that the rotation axis 10L of the nip roller 10 actually has a rotation axis parallel to the width direction (X direction) of the optical laminate S for each of the rollers 11 and 12, but since the rollers 11 and 12 are arranged opposite to each other in the vertical direction (Z direction), in the plan view viewed from the vertical direction (Z direction) shown in FIG. 1B, it appears to have a common single rotation axis 10L.
Similarly, in the conventional manufacturing apparatus, the rotation axis (center of rotation) 30L of the second guide roller 30 is parallel to the rotation axis (center of rotation) 10L of the nip roller 10. In other words, the rotation axis 30L of the second guide roller 30 is parallel to the width direction (X direction) of the optical laminate S, like the rotation axis 10L of the nip roller 10.

Since the first optical film F1 and the second optical film F2 are laterally stretched films, slack may occur at either end in the width direction. Fig. 1(a) illustrates a case where slack occurs on the DS side of the first optical film F1 and slack occurs on the OS side of the second optical film F2.
When the first optical film F1 and/or the second optical film F2 have slack at the width direction end, as in the manufacturing method using the conventional manufacturing apparatus shown in FIG. 1, when these optical films F1 and F2 are guided by guide rollers 20 and 30 having rotation axes 20L and 30L parallel to the rotation axis 10L of the nip roller 10 and laminated together by the nip roller 10, wrinkles S1 and surface scratches (scratches) may occur in the optical laminate S obtained by lamination due to the influence of slack. In addition, curls (warping of the end) may occur in the optical laminate S after cutting to the product size due to the influence of slack. The manufacturing apparatus of the present embodiment and the manufacturing method using the same solve these problems.

<Method for producing optical laminate according to the first embodiment>
3 is a diagram for explaining a schematic configuration of a manufacturing apparatus for carrying out the manufacturing method of the optical laminate according to the first embodiment. Fig. 3(a) is a perspective view showing a schematic configuration of the manufacturing apparatus. Fig. 3(b) is a plan view showing a schematic configuration of the manufacturing apparatus. In Fig. 3(b), the first optical film F1, the second optical film F2, and the optical laminate S are omitted.
As shown in FIG. 3, the manufacturing apparatus of the first embodiment also includes a nip roller 10 and guide rollers (a first guide roller 20 and a second guide roller 30) like the conventional manufacturing apparatus shown in FIG.

The nip roller 10 is composed of a pair of rollers 11, 12 arranged opposite to each other, and is a roller for sandwiching and laminating a long first optical film F1 and a long second optical film F2, which are respectively transported in the longitudinal direction, between the pair of rollers 11, 12. In the example shown in Fig. 3, the rollers 11, 12 are arranged opposite to each other in the vertical direction (Z direction).
The first guide roller 20 is positioned upstream of the nip roller 10 in the transport direction of the first optical film F1, and is a roller that guides the first optical film F1 toward the nip roller 10 (specifically, toward the space between the pair of rollers 11, 12).
The second guide roller 30 is positioned upstream of the nip roller 10 in the transport direction of the second optical film F2, and is a roller that guides the second optical film F2 toward the nip roller 10 (specifically, toward the space between the pair of rollers 11, 12).
The configuration described above is the same as that of the conventional manufacturing apparatus shown in FIG.

However, in the manufacturing apparatus of the first embodiment, the posture of the first guide roller 20 is different from the posture of the first guide roller 20 shown in Fig. 1. As shown in Fig. 3B, in the manufacturing apparatus of the first embodiment, the rotation axis 20L of the first guide roller 20 is inclined from the parallel state (shown by the dashed line in Fig. 3B) to the rotation axis 10L of the nip roller 10.
Specifically, the example shown in Fig. 3(a) illustrates a case where slack occurs only on the DS side of the first optical film F1 (no slack occurs in the second optical film F2). For this reason, as shown in Fig. 3(b), in the manufacturing apparatus of the first embodiment, the posture of the first guide roller 20 is adjusted so that the rotation axis 20L of the first guide roller 20 is inclined from a state in which the rotation axis 20L of the first guide roller 20 is parallel to the rotation axis 10L of the nip roller 10 toward the direction in which the first guide roller 20 moves away from the end of the first optical film F1 on the DS side where slack occurs. More specifically, as can be seen from FIG. 3( a ), the first optical film F1 (not shown in FIG. 3( b )) is located below the first guide roller 20 (the lower side of the plane of the paper in FIG. 3( b )). However, as shown in FIG. 3( b ), the end (the DS-side end) of the rotation shaft 20L of the first guide roller 20 located at the end side of the DS side where slack is occurring in the first optical film F1 has moved by ΔY1 in a direction away from the end of the DS side where slack is occurring in the first optical film _F1 (upward in the Y direction shown in FIG. 3( b )).

In order to easily move the end of the rotation axis 20L of the first guide roller 20 as described above, a so-called take-up roller may be used as the first guide roller 20. The take-up roller is a roller that includes a roller body, a support means for fixing and supporting one end of the roller body (the end on the OS side in the example shown in FIG. 3), and a one-axis stage that supports the other end of the roller body (the end on the DS side in the example shown in FIG. 3) and moves in a direction perpendicular to the rotation axis 20L in the initial state (parallel to the rotation axis 10L of the nip roller 10) (the Y direction in the example shown in FIG. 3). By moving this one-axis stage, it is possible to easily move the other end of the roller body. In other words, it is possible to easily move the end of the rotation axis 20L of the first guide roller 20.

When slack occurs at the end of the first optical film F1 on the DS side as shown in FIG. 3(a), in the manufacturing method according to the first embodiment, the first optical film F1 is guided by a first guide roller 20 having a rotation axis 20L adjusted to be inclined in a specific direction relative to the rotation axis 10L of the nip roller 10, and is laminated by the nip roller 10. This makes it possible to suppress the occurrence of wrinkles S1 (see FIG. 1) and surface defects in the optical laminate S obtained by lamination, and also makes it possible to suppress curling of the optical laminate S after cutting to the product size.

<Method for producing optical laminate according to the second embodiment>
Fig. 4 is a diagram for explaining the schematic configuration of a manufacturing apparatus for carrying out the manufacturing method of the optical laminate according to the second embodiment. Fig. 4(a) is a perspective view showing the schematic configuration of the manufacturing apparatus. Fig. 4(b) is a plan view showing the schematic configuration of the manufacturing apparatus. In Fig. 4(b), the first optical film F1, the second optical film F2, and the optical laminate S are omitted.
As shown in Fig. 4, the manufacturing apparatus of the second embodiment also includes a nip roller 10 and guide rollers (a first guide roller 20 and a second guide roller 30) like the manufacturing apparatus of the first embodiment shown in Fig. 3. Below, differences from the manufacturing apparatus of the first embodiment will be mainly described, and descriptions of the same points will be omitted as appropriate.

In the manufacturing apparatus of the second embodiment, the posture of the second guide roller 30 is different from the posture of the second guide roller 30 shown in Fig. 1. As shown in Fig. 4B, in the apparatus of the second embodiment, the rotation axis 30L of the second guide roller 30 is inclined from the parallel state (shown by the dashed line in Fig. 4B) to the rotation axis 10L of the nip roller 10.
Specifically, the example shown in Fig. 4(a) illustrates a case where slack occurs only on the OS side of the second optical film F2 (no slack occurs in the first optical film F1). For this reason, as shown in Fig. 4(b), in the manufacturing apparatus of the second embodiment, the posture of the second guide roller 30 is adjusted so that the rotation axis 30L of the second guide roller 30 is inclined from a state in which the rotation axis 30L of the second guide roller 30 is parallel to the rotation axis 10L of the nip roller 10 toward the direction in which the second guide roller 30 moves away from the end of the OS side where slack occurs in the second optical film F2. More specifically, as can be seen from FIG. 4( a ), the second optical film F2 (not shown in FIG. 4( b )) is located below the second guide roller 30 (the lower side of the paper in FIG. 4( b )). However, as shown in FIG. 4( b ), the end (the OS-side end) of the rotation shaft 30L of the second guide roller 30 located at the end side of the OS side where slack is occurring in the second optical film F2 has moved by _ΔY2 in a direction away from the end side of the OS side where slack is occurring in the second optical film F2 (upward in the Y direction shown in FIG. 4( b )).

In order to easily move the end of the rotation axis 30L of the second guide roller 30 as described above, a so-called take-up roller may be used as the second guide roller 30. The take-up roller is a roller that includes a roller body, a support means for fixing and supporting one end of the roller body (the end on the DS side in the example shown in FIG. 4), and a uniaxial stage that supports the other end of the roller body (the end on the OS side in the example shown in FIG. 4) and moves in a direction perpendicular to the rotation axis 30L in the initial state (parallel to the rotation axis 10L of the nip roller 10) (the Y direction in the example shown in FIG. 4). By moving this uniaxial stage, it is possible to easily move the other end of the roller body. That is, it is possible to easily move the end of the rotation axis 30L of the second guide roller 30.

When slack occurs at the end of the second optical film F2 on the OS side as shown in FIG. 4(a), in the manufacturing method according to the second embodiment, the second optical film F2 is guided by a second guide roller 30 having a rotation axis 30L adjusted to be inclined in a specific direction relative to the rotation axis 10L of the nip roller 10, and is laminated by the nip roller 10. This makes it possible to suppress the occurrence of wrinkles S1 (see FIG. 1) and surface defects in the optical laminate S obtained by lamination, and also makes it possible to suppress curling of the optical laminate S after cutting to the product size.

<Method for producing optical laminate according to the third embodiment>
Fig. 5 is a diagram for explaining the schematic configuration of a manufacturing apparatus for carrying out the manufacturing method of the optical laminate according to the third embodiment. Fig. 5(a) is a perspective view showing the schematic configuration of the manufacturing apparatus. Fig. 5(b) is a plan view showing the schematic configuration of the manufacturing apparatus. In Fig. 5(b), the first optical film F1, the second optical film F2, and the optical laminate S are omitted.
As shown in Fig. 5, the manufacturing apparatus of the third embodiment also includes a nip roller 10 and guide rollers (first guide roller 20, second guide roller 30) like the manufacturing apparatus of the first embodiment shown in Fig. 3 and the manufacturing apparatus of the second embodiment shown in Fig. 4. Below, differences from the manufacturing apparatus of the first embodiment and the manufacturing apparatus of the second embodiment will be mainly described, and descriptions of the same points will be omitted as appropriate.

In the manufacturing apparatus of the third embodiment, the posture of the first guide roller 20 is different from that of the first guide roller 20 shown in FIG. 1. Also, the posture of the second guide roller 30 is different from that of the second guide roller 30 shown in FIG. 1. As shown in FIG. 5B, in the apparatus of the third embodiment, the rotation axis 20L of the first guide roller 20 is inclined from a parallel state (shown by a dashed line in FIG. 5B) to the rotation axis 10L of the nip roller 10. Also, in the manufacturing apparatus of the third embodiment, the rotation axis 30L of the second guide roller 30 is inclined from a parallel state (shown by a dashed line in FIG. 5B) to the rotation axis 10L of the nip roller 10.
Specifically, the example shown in Fig. 5(a) illustrates a case where slack occurs on the DS side of the first optical film F1 and the OS side of the second optical film F2. For this reason, as shown in Fig. 5(b), in the manufacturing device of the third embodiment, the posture of the first guide roller 20 is adjusted so that the rotation axis 20L of the first guide roller 20 is inclined from a state in which the rotation axis 20L of the first guide roller 20 is parallel to the rotation axis 10L of the nip roller 10 toward the direction in which the first guide roller 20 moves away from the end of the DS side where the slack occurs in the first optical film F1. In addition, in the manufacturing device of the third embodiment, the posture of the second guide roller 30 is adjusted so that the rotation axis 30L of the second guide roller 30 is inclined from a state in which the rotation axis 30L of the second guide roller 30 is parallel to the rotation axis 10L of the nip roller 10 toward the direction in which the second guide roller 30 moves away from the end of the OS side where the slack occurs in the second optical film F2. More specifically, as can be seen from FIG. 5( a ), the first optical film F1 (not shown in FIG. 5( b )) is located below the first guide roller 20 (the lower side of the plane of the paper in FIG. 5( b )). However, as shown in FIG. 5( b ), the end (the DS-side end) of the rotation shaft 20L of the first guide roller 20 located at the end side of the DS side where slack is occurring in the first optical film F1 has moved by ΔY1 in a direction away from the end of the DS side where slack is occurring in the first optical film _F1 (upward in the Y direction shown in FIG. 5( b )). As can be seen from FIG. 5( a ), the second optical film F2 (not shown in FIG. 5( b )) is located below the second guide roller 30 (the lower side of the paper in FIG. 5( b )). However, as shown in FIG. 5( b ), the end (the OS-side end) of the rotation shaft 30L of the second guide roller 30 located at the end side of the OS side where slack is occurring in the second optical film F2 has moved by _ΔY2 in a direction away from the end side of the OS side where slack is occurring in the second optical film F2 (upward in the Y direction shown in FIG. 5( b )).

In order to easily move the end of the rotation shaft 20L of the first guide roller 20 and the end of the rotation shaft 30L of the second guide roller 30 as described above, so-called take-up rollers can be used as the first guide roller 20 and the second guide roller 30. Details of the take-up rollers are as described above.

When slack is present at the DS-side end of the first optical film F1 and the OS-side end of the second optical film F2 as shown in FIG. 5(a), in the manufacturing method according to the third embodiment, the first optical film F1 is guided by a first guide roller 20 having a rotation axis 20L adjusted to be inclined in a specific direction relative to the rotation axis 10L of the nip roller 10, and the second optical film F2 is guided by a second guide roller 30 having a rotation axis 30L adjusted to be inclined in a specific direction relative to the rotation axis 10L of the nip roller 10, and the two films are bonded together by the nip roller 10. This makes it possible to suppress the occurrence of wrinkles S1 (see FIG. 1) and surface defects in the optical laminate S obtained by bonding, and also makes it possible to suppress curling of the optical laminate S after cutting to the product size.

In the above-described embodiment, the first optical film F1 is a protective film and the second optical film F2 is a separator, but the present invention is not limited to this. For example, the present invention can be applied to various combinations of the first optical film F1 and the second optical film F2, such as a case where the first optical film F1 is a polarizing film with a surface protective film and the second optical film F2 is a separator.

In addition, in this embodiment, an example has been described in which both the first guide roller 20 and the second guide roller 30 are disposed, but if slack occurs in only one of the first optical film F1 and the second optical film F2, it is also possible to dispose only the guide roller corresponding to the optical film in which slack occurs (for example, if slack occurs only in the first optical film F1, it is possible to dispose only the first guide roller 20).

Furthermore, in this embodiment, the end of the rotation shaft 20L of the first guide roller 20 (or the rotation shaft 30L of the second guide roller 30) located on the end side of the side where the slackness of the first optical film F1 (or the second optical film F2) occurs is adjusted to a state in which it moves in a direction away from the end of the side where the slackness of the first optical film F1 (or the second optical film F2) occurs, but the present invention is not limited to this. It is also possible to adjust the end of the rotation shaft 20L of the first guide roller 20 (or the rotation shaft 30L of the second guide roller 30) located on the end side opposite the end of the side where the slackness of the first optical film F1 (or the second optical film F2) occurs to a state in which it moves in a direction approaching the end of the side opposite the end of the side where the slackness of the first optical film F1 (or the second optical film F2) occurs. For example, in the first embodiment, as shown in FIG. 3, the end (DS side end) of the rotation shaft 20L of the first guide roller 20 is adjusted to a state in which it moves in a direction away from the DS side end where slack occurs in the first optical film F1, but this is not limited thereto, and it is also possible to adjust the end (OS side end) of the rotation shaft 20L of the first guide roller 20 to a state in which it moves in a direction approaching the OS side end opposite the DS side end where slack occurs in the first optical film F1.

Below, an example of the results of a test conducted to manufacture an optical laminate S using the manufacturing method for the optical laminate S according to this embodiment (Examples 1 to 3), the manufacturing method for the optical laminate S according to the comparative examples (Comparative Examples 1 to 3), and the manufacturing method for the optical laminate S according to the reference example will be described.

Example 1
An acrylic adhesive was applied to a long substrate layer F11 (thickness 75 μm) made of biaxially stretched polyethylene terephthalate so that the thickness after drying was 50 μm with a fountain roll, and this was dried to form an adhesive layer F12. In this way, a long first optical film F1 was produced as a protective film in which the substrate layer F11 and the adhesive layer F12 were laminated.
In the first optical film F1, slack occurred on the DS side, and the amount of slack _ΔS1 was 3 mm (see FIG. 3(a)).

FIG. 6 is a diagram for explaining a method for measuring the amount of slack _ΔS1 .
When measuring the amount of slack _ΔS1 , the first optical film F1 was first stretched between predetermined rolls under tension. In this state, as shown in Fig. 6, the position of the laser range finder 40 in the width direction (X direction) of the first optical film F1 was changed, and the distance to the surface of the first optical film F1 was measured by the laser range finder 40 at each position. The difference between the measured maximum and minimum distances was then calculated as the amount of slack _ΔS1 . The same applies to the method for measuring the amount of slack _ΔS2 of the second optical film F2 described below.

Meanwhile, one side of a long biaxially stretched polyethylene terephthalate film was surface-coated with a silicone-based release agent to produce a long second optical film F2, which was a separator with a thickness of 25 μm.

The first optical film F1 and the second optical film F2 prepared as described above were guided by the first guide roller 20 and the second guide roller 30, respectively, in the nip roller 10 so that the pressure-sensitive adhesive layer F12 of the first optical film F1 and the surface-coated surface of the second optical film F2 faced each other, and were bonded together by the nip roller 10 to produce an optical laminate S.
At this time, the end (DS side end) of the rotation shaft 20L of the first guide roller 20 was previously adjusted to a state in which it had moved 5 mm in a direction (upward in the Y direction shown in FIG. 3B) away from the end of the DS side where the slack in the first optical film F1 was occurring ( _ΔY1 =+5 mm, see FIG. 3A). As a result, the rotation shaft 20L of the first guide roller 20 was inclined by 0.15° from a state parallel to the rotation shaft 10L of the nip roller 10. The rotation shaft 30L of the second guide roller 30 was kept parallel to the rotation shaft 10L of the nip roller 10. In this specification, _ΔY1 is expressed as a positive value in the direction away from the first optical film F1 and as a negative value in the direction approaching the first optical film F1.

Example 2
As in Example 1, an acrylic adhesive was applied to a long substrate layer F11 (thickness 75 μm) made of biaxially stretched polyethylene terephthalate so that the thickness after drying was 50 μm with a fountain roll, and this was dried to form an adhesive layer F12. In this way, a long first optical film F1 was produced as a protective film in which the substrate layer F11 and the adhesive layer F12 were laminated.

On the other hand, one side of a long biaxially stretched polyethylene terephthalate film was surface-coated with a silicone-based release agent to prepare a long second optical film F2 serving as a separator having a thickness of 25 μm.
In the second optical film F2, slack was generated on the OS side, and the amount of slack _ΔS2 was 3 mm (see FIG. 4(a)).
The optical film in which slack occurs (the second optical film F2 in Example 2), the end portion on the side where slack occurs (the OS side in Example 2), and the amount of slack (3 mm in Example 2) are different from those in Example 1, which are believed to be due to the following reasons.
Usually, a biaxially stretched long polyethylene terephthalate film is manufactured by sequentially performing each process of melt extrusion, longitudinal stretching, and transverse stretching. Even if the raw materials are the same, differences occur in the molecular weight distribution of the resin, and therefore differences also occur in the melt viscosity, which may cause a change in the thickness distribution of the film during melt extrusion. For this reason, feedback control is usually performed to adjust the thickness during melt extrusion so that the thickness distribution after biaxial stretching is uniform, but as a result, the effective stretch ratio in the width direction changes slightly. Due to this, even if the raw materials are the same polyethylene terephthalate, it is thought that differences occur in the optical film where slack occurs, the end portion on the side where slack occurs, and the amount of slack. The same is true for Examples 3 and 4.

The first optical film F1 and the second optical film F2 prepared as described above were guided by the first guide roller 20 and the second guide roller 30, respectively, in the nip roller 10 so that the pressure-sensitive adhesive layer F12 of the first optical film F1 and the surface-coated surface of the second optical film F2 faced each other, and were bonded together by the nip roller 10 to produce an optical laminate S.
At this time, the end (the end on the OS side) of the rotation shaft 30L of the second guide roller 30 was previously adjusted to a state in which it had moved 5 mm in a direction (upward in the Y direction shown in FIG. 4(b)) away from the end on the OS side where the slack in the second optical film F2 had occurred ( _ΔY2 =+5 mm, see FIG. 4(a)). As a result, the rotation shaft 30L of the second guide roller 30 was inclined by 0.15° from a state parallel to the rotation shaft 10L of the nip roller 10. The rotation shaft 20L of the first guide roller 20 was kept parallel to the rotation shaft 10L of the nip roller 10. In this specification, _ΔY2 is expressed as a positive value in the direction away from the second optical film F2 and as a negative value in the direction approaching the second optical film F2.

Example 3
As in Example 1, an acrylic adhesive was applied to a long substrate layer F11 (thickness 75 μm) made of biaxially stretched polyethylene terephthalate so that the thickness after drying was 50 μm with a fountain roll, and this was dried to form an adhesive layer F12. In this way, a long first optical film F1 was produced as a protective film in which the substrate layer F11 and the adhesive layer F12 were laminated.
In the first optical film F1, slack was generated on the DS side, and the amount of slack _ΔS1 was 7 mm (see FIG. 5(a)).

On the other hand, one side of a long biaxially stretched polyethylene terephthalate film was surface-coated with a silicone-based release agent to prepare a long second optical film F2 serving as a separator having a thickness of 25 μm.
In the second optical film F2, slack was generated on the OS side, and the amount of slack _ΔS2 was 5 mm (see FIG. 5(a)).

The first optical film F1 and the second optical film F2 prepared as described above were guided by the first guide roller 20 and the second guide roller 30, respectively, in the nip roller 10 so that the pressure-sensitive adhesive layer F12 of the first optical film F1 and the surface-coated surface of the second optical film F2 faced each other, and were bonded together by the nip roller 10 to produce an optical laminate S.
At this time, the end (DS side end) of the rotation shaft 20L of the first guide roller 20 was previously adjusted to a state in which it had moved 8 mm in a direction (upward in the Y direction shown in FIG. 5(b)) away from the DS side end where slack has occurred in the first optical film F1 ( _ΔY1 =+8 mm, see FIG. 5(a)). As a result, the rotation shaft 20L of the first guide roller 20 was inclined by 0.25° from a state in which it was parallel to the rotation shaft 10L of the nip roller 10. In addition, the end (OS side end) of the rotation shaft 30L of the second guide roller 30 was previously adjusted to a state in which it had moved 3 mm in a direction (upward in the Y direction shown in FIG. 5(b)) away from the OS side end where slack has occurred in the second optical film F2 ( _ΔY2 =+3 mm, see FIG. 5(a)). As a result, the rotation axis 30L of the second guide roller 30 was inclined by 0.09° relative to the rotation axis 10L of the nip roller 10 from a state in which it was parallel to the axis 10L.
In Example 2, when the amount of slack _ΔS2 was 3 mm, _ΔY2 was adjusted to +5 mm, and in Example 3, when the amount of slack _ΔS2 was 5 mm, _ΔY2 was adjusted to +3 mm. That is, when the amount of slack _ΔS2 was small (Example 2), the amount of movement _ΔY2 was adjusted to be larger. This is because, although the amount of slack _ΔS2 measured by the method shown in Fig. 6 was smaller in Example 2, the distribution of slack in the width direction of the second optical film F2 was wider in Example 2. In this way, the movement amount ΔY ₁ of the end of the rotation shaft 20L of the first guide roller 20 (the inclination angle of the rotation shaft 20L of the first guide roller 20) and the movement amount ΔY ₂ of the end of the rotation shaft 30L of the second guide roller 30 (the inclination angle of the rotation shaft 30L of the second guide roller 30) are adjusted to appropriate values, taking into account not only the slack amount ΔS ₁ of the first optical film F1 and the slack amount ΔS ₂ of the second optical film F2, but also the distribution of slack in the width direction.

Example 4
As in Example 1, an acrylic adhesive was applied to a long substrate layer F11 (thickness 75 μm) made of biaxially stretched polyethylene terephthalate so that the thickness after drying was 50 μm with a fountain roll, and this was dried to form an adhesive layer F12. In this way, a long first optical film F1 was produced as a protective film in which the substrate layer F11 and the adhesive layer F12 were laminated.
In the first optical film F1, slack was generated on the OS side, and the amount of slack _ΔS1 was 3 mm.

On the other hand, one side of a long biaxially stretched polyethylene terephthalate film was surface-coated with a silicone-based release agent to prepare a long second optical film F2 serving as a separator having a thickness of 25 μm.
In the second optical film F2, slack was generated on the OS side, and the amount of slack _ΔS2 was 3 mm.

The first optical film F1 and the second optical film F2 produced as described above were guided by the first guide roller 20 and the second guide roller 30, respectively, in the nip roller 10 so that the pressure-sensitive adhesive layer F12 of the first optical film F1 and the surface-coated surface of the second optical film F2 faced each other, and were bonded together by the nip roller 10 to produce an optical laminate S. As described above, since slack occurs on the same OS side for both the first optical film F1 and the second optical film F2, an optical laminate S is produced in which the end portion on the side where slack occurs of the first optical film F1 and the end portion on the side where slack occurs of the second optical film F2 are laminated.
At this time, the end (OS side end) of the rotation shaft 20L of the first guide roller 20 was previously adjusted to a state in which it was moved by 5 mm in a direction away from the end of the OS side where the slack of the first optical film F1 was occurring (ΔY ₁ = +5 mm). As a result, the rotation shaft 20L of the first guide roller 20 was in a state in which it was inclined by 0.15° from a state in which it was parallel to the rotation shaft 10L of the nip roller 10. In addition, the end (OS side end) of the rotation shaft 30L of the second guide roller 30 was previously adjusted to a state in which it was moved by 5 mm in a direction away from the end of the OS side where the slack of the second optical film F2 was occurring (ΔY ₂ = +5 mm). As a result, the rotation shaft 30L of the second guide roller 30 was in a state in which it was inclined by 0.15° from a state in which it was parallel to the rotation shaft 10L of the nip roller 10.

<Comparative Example 1>
Similarly to Example 1, a first optical film F1 and a second optical film F2 each having a slack amount ΔS ₁ = 3 mm were guided by a first guide roller 20 and a second guide roller 30, respectively, in the nip roller 10 so that the pressure-sensitive adhesive layer F12 of the first optical film F1 and the surface-coated surface of the second optical film F2 faced each other, and bonded together by the nip roller 10 to produce an optical laminate S.
At this time, unlike the first embodiment, the rotation axis 20L of the first guide roller 20 was kept parallel to the rotation axis 10L of the nip roller 10.

<Comparative Example 2>
Similarly to Example 2, the first optical film F1 and the second optical film F2 having a slack amount ΔS ₂ = 3 mm were guided by the first guide roller 20 and the second guide roller 30, respectively, in the nip roller 10 so that the pressure-sensitive adhesive layer F12 of the first optical film F1 and the surface-coated surface of the second optical film F2 faced each other, and bonded together by the nip roller 10 to produce an optical laminate S.
At this time, unlike the second embodiment, the rotation axis 30L of the second guide roller 30 was kept parallel to the rotation axis 10L of the nip roller 10.

<Comparative Example 3>
As in Example 3, a first optical film F1 having a slack amount ΔS ₁ = 7 mm and a second optical film F2 having a slack amount ΔS ₂ = 5 mm were guided by a first guide roller 20 and a second guide roller 30, respectively, in the nip roller 10 so that the pressure-sensitive adhesive layer F12 of the first optical film F1 and the surface-coated surface of the second optical film F2 faced each other, and bonded together by the nip roller 10 to produce an optical laminate S.
At this time, unlike Example 3, the rotation axis 20L of the first guide roller 20 and the rotation axis 30L of the second guide roller 30 were kept parallel to the rotation axis 10L of the nip roller 10.

<Reference Example>
7A and 7B are diagrams for explaining the schematic configuration of a manufacturing apparatus for carrying out a manufacturing method of an optical laminate S according to a reference example. Fig. 7A is a perspective view showing the schematic configuration of the manufacturing apparatus. Fig. 7B is a plan view showing the schematic configuration of the manufacturing apparatus. In Fig. 7B, the first optical film F1, the second optical film F2, and the optical laminate S are omitted.
As shown in FIG. 7, the manufacturing apparatus of the reference example also includes a nip roller 10 and guide rollers (first guide roller 20, second guide roller 30), similar to the manufacturing apparatus of the first embodiment (Example 1) shown in FIG.

In the reference example, similarly to Example 1, a first optical film F1 and a second optical film F2 having a slack amount ΔS ₁ = 3 mm (see FIG. 7( a)) were guided by a first guide roller 20 and a second guide roller 30, respectively, in the nip roller 10 so that the pressure-sensitive adhesive layer F12 of the first optical film F1 and the surface-coated surface of the second optical film F2 faced each other, and bonded together by the nip roller 10 to produce an optical laminate S.
At this time, unlike Example 1, the end (the end on the DS side) of the rotation shaft 20L of the first guide roller 20 was previously adjusted to be moved 5 mm in a direction approaching the end on the DS side where slack occurs in the first optical film F1 (downward in the Y direction shown in Figure 7(b)) (ΔY ₁ = -5 mm, see Figure 7(a)).

<Evaluation content and results>
The optical laminates S produced by the production methods according to Examples 1 to 4, the production method according to the comparative example, and the production method according to the reference example described above were evaluated for wrinkles, surface defects, and curls.
Concerning wrinkles, the presence or absence of wrinkles was confirmed by visual inspection.
Regarding surface defects, the number of surface defects occurring per unit length of the optical laminate S was confirmed.

8A and 8B are diagrams for explaining a method for evaluating the curl of the optical laminate S. Fig. 8A is a plan view showing the optical laminate S after cutting into a product size. Fig. 8B is a diagram for explaining the curl value C.
When evaluating the curl of the optical laminate S, as shown in FIG. 8(a), the long optical laminate S was cut into a product size. In the example shown in FIG. 8(a), the optical laminate S was cut into a size of 1000 mm in the width direction (X direction) and 1500 mm in the length direction (Y direction). Then, as shown in FIG. 8(b), the optical laminate S after cutting was placed on a flat mounting table 40 so that the warpage of the four corners of the optical laminate S after cutting, which are surrounded by dashed lines in FIG. 8(a), faces upward in the vertical direction (Z direction), and the vertical distance from the upper surface of the mounting table 40 to the upper end ST of the warpage was measured for each corner. The vertical distance from the upper surface of the mounting table 40 to the upper end ST of the warpage was measured by setting up a scale extending vertically near the warpage and visually reading the scale graduations. This measured distance was evaluated as a curl value C indicating the degree of curl.

Fig. 9 shows the evaluation results of the optical laminate S produced by the production method according to Comparative Example 1 and the production method according to the Reference Example. Fig. 9(a) shows the amount of slack in the first optical film F1 and the second optical film F2 common to Comparative Example 1 and the Reference Example. Fig. 9(b) shows the amount of movement of the first guide roller 20 and the second guide roller 30, and the evaluation results for wrinkles, surface scratches, and curls of the optical laminate S.
In FIG. 9, the mark "◎" in the "Wrinkles of optical laminate" column means that no wrinkles were visible in the optical laminate S, the mark "◯" means that almost no wrinkles were visible in the optical laminate S, and the mark "×" means that wrinkles were clearly visible in the optical laminate S. In addition, the mark "◯" in the "Surface flaws of optical laminate" column means that the number of surface flaws per 1 m of the optical laminate S was 5 or less, and the mark "×" means that the number of surface flaws per 1 m of the optical laminate S was 6 or more. In addition, the mark "◯" in the "Curl of optical laminate" column means that the curl values C of the four corners of the optical laminate S after cutting into the product size were all 5 mm or less, and the mark "×" means that any of the curl values C of the four corners of the optical laminate S after cutting into the product size exceeded 5 mm. The meanings of "◯" and "×" in each column are the same for FIGS. 10 to 13 described later.

As shown in Figure 9, in the manufacturing method of Comparative Example 1, the wrinkles and surface defects of the optical laminate S on the DS side were marked "x", but in the manufacturing method of the Reference Example, these were improved to "o". However, curls remained marked "x" on both the OS and DS sides, and it can be seen that no improvement was made.

Fig. 10 shows the evaluation results of the optical laminate S produced by the production method of Comparative Example 1 and the production method of Example 1. Fig. 10(a) shows the amount of slack in the first optical film F1 and the second optical film F2 common to Comparative Example 1 and Example 1. Fig. 10(b) shows the amount of movement of the first guide roller 20 and the second guide roller 30, and the evaluation results for wrinkles, surface scratches, and curl of the optical laminate S.
10, it can be seen that the wrinkles and surface scratches of the optical laminate S on the DS side were marked "x" in the production method of Comparative Example 1, but were improved to "o" in the production method of Example 1. It can also be seen that curl was improved to "o" on both the OS side and the DS side.

Fig. 11 shows the evaluation results of the optical laminate S produced by the production method of Comparative Example 2 and the production method of Example 2. Fig. 11(a) shows the amount of slack in the first optical film F1 and the second optical film F2 common to Comparative Example 2 and Example 2. Fig. 11(b) shows the amount of movement of the first guide roller 20 and the second guide roller 30, and the evaluation results for wrinkles, surface scratches, and curling of the optical laminate S.
As shown in FIG. 11, in the manufacturing method of Comparative Example 2, the wrinkles, surface scratches, and curls of the optical laminate S on the OS side were marked as "X", whereas in the manufacturing method of Example 2, all of these were improved to "O".

Fig. 12 shows the evaluation results of the optical laminate S produced by the production method of Comparative Example 3 and the production method of Example 3. Fig. 12(a) shows the amount of slack in the first optical film F1 and the second optical film F2 common to Comparative Example 3 and Example 3. Fig. 12(b) shows the amount of movement of the first guide roller 20 and the second guide roller 30, and the evaluation results for wrinkles, surface scratches, and curl of the optical laminate S.
As shown in FIG. 12, in the manufacturing method of Comparative Example 3, the wrinkles, surface scratches, and curls of the optical laminate S were marked as "X" on both the OS side and the DS side, whereas in the manufacturing method of Example 3, all of these were improved to "O".

Fig. 13 shows the evaluation results of the optical laminate S produced by the production method according to Example 4. Fig. 13(a) shows the amount of slack in the first optical film F1 and the second optical film F2 used in Example 4. Fig. 13(b) shows the amount of movement of the first guide roller 20 and the second guide roller 30, and the evaluation results for wrinkles, surface scratches, and curling of the optical laminate S.
As shown in Fig. 13, in the manufacturing method according to Example 4, the wrinkles of the optical laminate S are marked with "◎" on both the OS side and the DS side. In the manufacturing method according to Example 3 shown in Fig. 12, the end (DS side end) of the first optical film F1 on the side where the slack occurs and the end (OS side end) of the second optical film F2 on the side where the slack occurs are located on different sides, but in the manufacturing method according to Example 4, the end (OS side end) of the first optical film F1 on the side where the slack occurs and the end (OS side end) of the second optical film F2 on the side where the slack occurs are located on the same side, and an optical laminate S is produced in which these ends are laminated. Therefore, it can be seen that the wrinkles of the optical laminate S, which were marked with "◯" in the manufacturing method according to Example 3, are improved to "◎" in the manufacturing method according to Example 4.

As described above, the manufacturing methods of Examples 1 to 4 can suppress the occurrence of wrinkles and surface scratches in the optical laminate S, which could not be suppressed by the manufacturing methods of Comparative Examples 1 to 3, and can also suppress curling of the optical laminate S after cutting to the product size, which could not be suppressed by the manufacturing method of the Reference Example.

10: Nip roller 20: First guide roller (guide roller)
30: Second guide roller (guide roller)
10L, 20L, 30L...rotation shaft F1...first optical film F2...second optical film S...optical laminate

Claims (3)

A method for producing an optical laminate by laminating a transversely stretched long first optical film and a transversely stretched long second optical film together with a nip roller while transporting them in a longitudinal direction, comprising:
a guide roller that guides the first optical film and/or the second optical film toward the nip roller is disposed upstream of the nip roller in a transport direction of the first optical film and/or the second optical film,
adjusting the attitude of the guide roller so that the rotation axis of the guide roller is inclined from a state in which the rotation axis of the guide roller is parallel to the rotation axis of the nip roller toward a direction in which the guide roller moves away from one of both width direction end portions of the first optical film and/or the second optical film, the end portion being on a side where slack has occurred;
A method for producing an optical laminate. When both the first optical film and the second optical film have an end portion on a side where slack occurs, the first optical film and the second optical film are bonded together by the nip roller so that the end portion on the side where slack occurs of the first optical film and the end portion on the side where slack occurs of the second optical film are laminated.
A method for producing the optical laminate according to claim 1 . the first optical film is a protective film having a base layer and a pressure-sensitive adhesive layer,
the second optical film is a separator,
The pressure-sensitive adhesive layer of the first optical film is bonded to the second optical film.
A method for producing the optical laminate according to claim 1 or 2.

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