Method for manufacturing a laminated optical film, and method for transporting a laminated optical film.

Abstract

To provide a method of manufacturing a laminated optical film, which prevents scraps of a film from contaminating a conveyor line even when a liquid crystal-coated polarizer is used.SOLUTION: A method of manufacturing a laminated optical film is provided, comprising: a pasting step of introducing a first optical film 2 having a first optical functional layer 22 and a second optical functional layer 23, an adhesive layer 4, and a second optical film 3 arranged in the described order between a pair of turning pasting rollers to obtain a laminated optical film; and a conveying step of conveying the laminated optical film after peeling off a release base material film 21 therefrom. In the pasting step, a width W2 of the adhesive layer 4 is smaller than a width W1 of the second optical functional layer 23 and is smaller than a width W4 of the second optical film 3. In the conveying step, the laminated optical film after peeling off the release base material film 21 is conveyed such that conveying rollers do not come in contact with the first optical film side.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a laminated optical film and a method for transporting a laminated optical film. [Background technology]

[0002] Conventionally, polarizers have been used in image display devices such as liquid crystal displays and organic light-emitting diodes (OLEDs). In liquid crystal displays, linear polarizers or circular polarizers are used for image display and phase difference control, while in organic light-emitting diodes (OLEDs), circular polarizers are used to suppress ambient light reflection. As polarizers, which are components of polarizers, stretched films containing iodine as a dichroic dye have been widely used, but in recent years, liquid crystal coated polarizers formed by coating a composition containing a dichroic dye and a liquid crystal compound have been investigated (for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2020 / 179864 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Polarizing plates are laminated optical films made up of optical films with various functions stacked together. In the manufacture of polarizing plates, the optical films are bonded and separated to achieve the desired laminated configuration. This operation is generally performed while the optical films are being transported on a conveyor line.

[0005] When a liquid crystal coated polarizer is used as the polarizer, the transport line is sometimes contaminated with film scraps compared to when a conventional stretched film is used. According to the inventor's investigation, it was found that these scraps were torn off from the widthwise edges of the laminated optical film during transport. Therefore, the present invention aims to provide a manufacturing method for laminated optical films in which the transport line is not contaminated with film scraps, even when a liquid crystal coated polarizer is used. It also aims to provide a method for transporting laminated optical films. [Means for solving the problem]

[0006] According to the inventors' research, it was found that in laminated optical films, the edges in the width direction where the adhesive bonding the optical films together does not extend become unfixed free edges (hereinafter referred to as "edge flaps"), and these parts are prone to tearing and becoming scraps during transport. The thinner the edge flaps, the more easily they tear. For example, even if the adhesive does not extend to the edges in the width direction, if the film contains relatively thick films, it is less likely to tear. However, if the thicker films are peeled off during the transport process and only the thin films remain as edge flaps, the tendency for the edge flaps to tear becomes more pronounced.

[0007] Furthermore, further investigation by the inventors revealed that the edge fraying occurs when the transport roll comes into contact with the portion of the laminated optical film where edge fraying has occurred during transport.

[0008] Therefore, the present invention relates to a method for manufacturing a laminated optical film, comprising a lamination step of introducing a first optical film, an adhesive layer, and a second optical film between a pair of rotating lamination rolls in the order of arrangement in the direction connecting the pair of lamination rolls, and laminating the first optical film and the second optical film to obtain a laminated optical film, and a transport step of transporting the laminated optical film, wherein the first optical film comprises a release substrate film, a first optical functional layer, and a second optical functional layer in this order, and the second optical functional layer is a polarizer layer including a liquid crystal coated polarizer, and lamination The present invention provides a manufacturing method in which, during lamination in the process, the first optical film is positioned so that the side with the second optical functional layer faces the adhesive layer, the width of the adhesive layer is smaller than the width of the second optical functional layer and also smaller than the width of the second optical film, and the second optical functional layer and the second optical film are positioned so as to encompass the width of the adhesive layer, and in the transport process, the release substrate film is peeled off from the laminated optical film that has passed between a pair of lamination rolls, and after the release substrate film has been peeled off, the film is transported in such a way that the transport rolls do not come into contact with the side with the first optical functional layer.

[0009] In the lamination process, the first optical film and the second optical film are laminated with the adhesive layer being narrower than the second optical functional layer, which can result in edge fraying on the first optical film. However, in the transport process, after the release substrate film is peeled off, the transport roll is kept away from the first optical film, thus preventing tearing of the edge fraying even if it occurs.

[0010] During lamination, the width of the second optical functional layer may be smaller than the width of the first optical functional layer, and the first optical functional layer may be positioned to encompass the width of the second optical functional layer.

[0011] In the present invention, the thickness of the portion of the first optical film excluding the release substrate film may be 1 μm to 10 μm. Since edge strips of this thickness are particularly prone to tearing, this is a suitable application for the present invention.

[0012] In the present invention, the width of the pair of laminating rolls may be greater than the width of either the first optical film or the second optical film, and the pair of laminating rolls may be positioned to encompass the width of both the first and second optical films. This ensures that the pressure from the laminating rolls is evenly applied to the entire optical film being laminated.

[0013] In the present invention, the liquid crystal coated polarizer may be a cured product of a polymerizable liquid crystal composition comprising a dichroic dye and a polymerizable liquid crystal compound having at least one polymerizable group.

[0014] In the present invention, the first optical functional layer may be a hard coat layer. Furthermore, in the present invention, the first optical film may further comprise an overcoat layer coated on the second optical functional layer. Also, in the present invention, the second optical film may consist of a plurality of layers, and the plurality of layers may include a phase difference layer.

[0015] In the present invention, the adhesive is an active energy ray curing type adhesive, and the invention may include a curing step in which the adhesive is cured by irradiating the laminate that has passed between a pair of bonding rolls with active energy rays.

[0016] Furthermore, the present invention provides a method for transporting a long laminated optical film comprising a hard coat layer, a polarizer layer, an adhesive layer, and a phase difference layer in this order, wherein, with respect to the width in a direction perpendicular to the transport direction, the width of the adhesive layer is smaller than the width of the polarizer layer and also smaller than the width of the phase difference layer, the polarizer layer and the phase difference layer are positioned to encompass the width of the adhesive layer, the hard coat layer is the outermost layer, and the method provides a transport method for transporting the laminated optical film without the transport rolls coming into contact with the hard coat layer. [Effects of the Invention]

[0017] According to the present invention, as a method for manufacturing a laminated optical film, even when a liquid crystal coating type polarizer is adopted, it is possible to provide a manufacturing method in which the conveyance line is not contaminated by the cut ends of the film. Further, according to the present invention, a method for conveying a laminated optical film can be provided.

Brief Description of the Drawings

[0018] [Figure 1] It is a cross-sectional view of a laminated optical film manufactured by the manufacturing method of the present embodiment. [Figure 2] It is a cross-sectional view of a laminated optical film manufactured by the manufacturing method of the present embodiment. [Figure 3] It is a diagram showing the manufacturing method of the present embodiment. [Figure 4] It is a cross-sectional view taken along line IV-IV of FIG. 3, showing the laminated state during bonding.

Embodiments for Carrying Out the Invention

[0019] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same parts or corresponding parts are denoted by the same reference numerals, and duplicate descriptions are omitted. Also, the dimensional ratios in each drawing do not necessarily match the actual ones, and in particular, the thickness and width of the film are exaggeratedly drawn.

[0020] The manufacturing method of the laminated optical film of the present embodiment forms a part of the manufacturing process of a circular polarizing plate including a polarizer layer, a hard coat layer, an overcoat layer, and a retardation layer, and obtains a long laminated optical film by bonding two optical films with an adhesive using a pair of rotating bonding rolls.

[0021] <Laminated Optical Film> First, the structure of the laminated optical film will be described. As shown in Figure 1, the laminated optical film 1A manufactured by the manufacturing method of this embodiment is formed by laminating a first optical film 2A and a second optical film 3 with an adhesive layer 4. The laminated optical film 1B shown in Figure 2 is obtained by peeling the release substrate film 21 off the laminated optical film 1A. Below, the laminated optical film 1A shown in Figure 1 will be used as an example for explanation.

[0022] In the laminated optical film 1A, the first optical film 2A comprises a release substrate film 21, a hard coat layer (first optical functional layer) 22, a polarizer layer (second optical functional layer) 23, and an overcoat layer 24 in this order. These layers are formed by sequentially applying raw resin to the release substrate film 21 as a base material. The second optical film 3 consists of multiple layers, comprising a release substrate film 32 and a phase difference layer (third optical functional layer) 31. These layers are formed by applying the raw resin of the phase difference layer 31 to the release substrate film 32 as a base material. The first optical film 2A and the second optical film 3 are arranged so that the overcoat layer 24 and the phase difference layer 31 face each other, and are bonded together with an adhesive layer 4.

[0023] In the first optical film 2A, the release substrate film 21 and the hard coat layer 22 are of equal width and aligned at both ends, the width of the polarizer layer 23 is smaller than the width of the hard coat layer 22, and the polarizer layer 23 and the overcoat layer 24 are of equal width and aligned at both ends. In the second optical film, the release substrate film 32 and the phase difference layer 31 are of equal width and aligned at both ends. The width of the adhesive layer 4 is smaller than the width of the polarizer layer 23 and also smaller than the width of the phase difference layer 31. In this specification, the "width" of each film or layer refers to the width in the direction perpendicular to the transport direction of each film or layer during the manufacturing of the laminated optical film 1A, and the width in the direction of extension of the lamination roll. In other words, Figure 1 is a cross-sectional view taken in a direction perpendicular to the transport direction during manufacturing. In addition, the relative size relationship (wide / narrow relationship) of each film or layer is expressed as "larger" and "smaller".

[0024] The release substrate film 21, the hard coat layer 22, the polarizer layer 23, the overcoat layer 24, the adhesive layer 4, the phase difference layer 31, and the release substrate film 32 have their central axes in the width direction substantially aligned. That is, the lamination configuration is substantially symmetrical in the cross-sectional view shown in Figure 1.

[0025] The laminated optical film 1B shown in Figure 2 is obtained by peeling the release substrate film 21 off the laminated optical film 1A. The ends of the first optical film 2B in the width direction that are not reached by the adhesive layer 4 are end flaps 10. Since the end flaps 10 are not fixed by the adhesive layer 4, they can move freely.

[0026] Here, we will describe each film or layer. (Release film) Various resin materials can be used as the release substrate films 21 and 32, for example, polyethylene terephthalate (PET) resin, polypropylene resin, triacetylcellulose (TAC) resin, and polycarbonate resin. The thickness of the release substrate films 21 and 32 is preferably 20 to 500 μm, more preferably 30 to 300 μm, and even more preferably 35 to 200 μm.

[0027] (Hard coat layer) The hard coat layer 22 is provided to improve the hardness and scratch resistance of the surface of the polarizer layer 23. The hard coat layer 22 may contain an ultraviolet absorber. The hard coat layer 22 is, for example, a cured layer of an ultraviolet-curable resin, and examples of ultraviolet-curable resins include acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, epoxy resins, etc. A method for forming the hard coat layer 22 is to apply the raw material resin onto the release substrate film 21 and cure it.

[0028] The thickness of the hard coat layer 22 may be 1 μm to 20 μm, or 2 μm to 7 μm.

[0029] (Polarizer layer) The polarizer layer 23 has at least a liquid crystal coated polarizer (hereinafter simply referred to as "polarizer") as a component, and also has an alignment film. The alignment film is a film made of a polymer compound and has an alignment restricting force that causes polymerizable liquid crystal compounds to be liquid crystal aligned in a desired direction.

[0030] In this embodiment, the polarizer is obtained by coating the surface of an alignment film with a composition (polymerizable liquid crystal composition) containing a dichroic dye and a polymerizable liquid crystal compound having at least one polymerizable group, and polymerizing the polymerizable liquid crystal compound. Therefore, this polarizer is a cured product of the polymerizable liquid crystal composition, and is a film in which the dichroic dye is dispersed and oriented within a film composed of a polymer of the polymerizable liquid crystal compound.

[0031] From the viewpoint of the orientation of the polymerizable liquid crystal compound, the thickness of the polarizer is preferably 0.5 μm to 3 μm, and more preferably 1 μm to 3 μm. If the thickness of the polarizer is greater than the lower limit, the polymerizable liquid crystal compound is less likely to orient in the vertical orientation direction, so the orientation order tends to improve. Also, if the thickness of the polarizer is less than the upper limit, the polymerizable liquid crystal compound is less likely to orient randomly, so the orientation order tends to improve. The thickness of the polarizer can be measured using an interferometer, laser microscope, or stylus-type film thickness gauge.

[0032] A polymerizable liquid crystal compound is a compound that has at least one polymerizable group and exhibits liquid crystalline properties. A polymerizable group is a group that participates in the polymerization reaction, and it is preferably a photopolymerizable group. Here, a photopolymerizable group is a group that can participate in the polymerization reaction by active radicals or acids generated from a photopolymerization initiator, which will be described later. Examples of polymerizable groups include vinyl groups, vinyloxy groups, 1-chlorovinyl groups, isopropenyl groups, 4-vinylphenyl groups, acryloyloxy groups, methacryloyloxy groups, oxyranyl groups, and oxetanyl groups. Among these, acryloyloxy groups, methacryloyloxy groups, vinyloxy groups, oxyranyl groups, and oxetanyl groups are preferred, and acryloyloxy groups are more preferred. The liquid crystalline properties may be thermotropic liquid crystal or lyotropic liquid crystal.

[0033] Dichroic dyes are dyes that have different absorbances along the long axis and short axis of the molecule. Dichroic dyes with an absorption maximum wavelength (λMAX) in the range of 300 to 700 nm are preferred. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes, with azo dyes being preferred. Examples of azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakisazo dyes, and stilbenazo dyes, with bisazo and trisazo dyes being preferred. Dichroic dyes may be used individually or in combination of two or more, but a combination of three or more is preferred. In particular, a combination of three or more azo compounds is even more preferred.

[0034] The alignment film facilitates the liquid crystal alignment of polymerizable liquid crystal compounds. The state of liquid crystal alignment, such as horizontal alignment, vertical alignment, hybrid alignment, and tilted alignment, changes depending on the properties of the alignment film and the polymerizable liquid crystal compound, and any combination can be arbitrarily selected. The alignment film is preferably insoluble in the solvent used when forming polarizers on the alignment film, and also has heat resistance for solvent removal and heat treatment for liquid crystal alignment. Examples of alignment films include alignment films made of aligning polymers, photo-alignment films, and groove alignment films, with photo-alignment films being preferred. The thickness of the alignment film is usually in the range of 10 nm to 500 nm, preferably in the range of 10 nm to 200 nm, and more preferably in the range of 30 nm to 100 nm.

[0035] Of the first optical film 2A, the total thickness of the layers other than the outermost release substrate film 21 is preferably 1 μm to 10 μm, and more preferably 2 μm to 8 μm. In particular, the sum of the thickness of the hard coat layer 22 and the polarizer layer 23 is preferably 1 μm to 8 μm, and more preferably 2 μm to 6 μm. Even if the total thickness of each layer is as thin as within this range, according to the manufacturing method of this embodiment described later, even if the release substrate film 21 is peeled off and edge flap 10 is generated, the tearing of the edge flap 10 is suppressed, making this method suitable for application.

[0036] (Overcoat layer) The overcoat layer 24 is composed of a material with low compatibility with the dichroic dye contained in the polarizer, and is a layer that has the function of preventing the movement (diffusion) of the dichroic dye. The overcoat layer 24 can also protect the polarizer layer 23 and provide a barrier against oxygen and moisture. The overcoat layer 24 may be provided on both sides of the polarizer layer 23 or on one side. Figure 1 shows an embodiment in which it is provided on one side. The overcoat layer 24 can be formed by applying a material (composition) for forming the overcoat layer 24 onto the polarizer layer 23.

[0037] The overcoat layer 24 is preferably made of a material that is excellent in solvent resistance, transparency, mechanical strength, thermal stability, shielding properties, and isotropy. The overcoat layer 24 provided on one side of the polarizer layer 23 may be one layer or two or more layers. If there are two or more overcoat layers 24, the materials constituting each layer may be the same or different. Also, if the overcoat layer 24 is provided on both sides of the polarizer layer 23, each overcoat layer 24 may be made of the same material or different materials. Examples of materials constituting the overcoat layer 24 include photocurable resins and water-soluble polymers.

[0038] Examples of photocurable resins include (meth)acrylic resins, urethane resins, (meth)acrylic urethane resins, epoxy resins, and silicone resins. Examples of water-soluble polymers include poly(meth)acrylamide polymers; polyvinyl alcohol and vinyl alcohol polymers such as ethylene-vinyl alcohol copolymers, ethylene-vinyl acetate copolymers, and (meth)acrylic acid or its anhydride-vinyl alcohol copolymers; carboxyvinyl polymers; polyvinylpyrrolidone; starches; sodium alginate; and polyethylene oxide polymers.

[0039] The thickness of the overcoat layer 24 is not particularly limited, but is preferably 20 μm or less, more preferably 15 μm or less, even more preferably 10 μm or less, may be 5 μm or less, and may be 0.05 μm or more, or 0.5 μm or more.

[0040] (Light transmittance of the first optical film) With respect to the light transmittance of the first optical film 2A, it is preferable that the first optical film 2A comprising each of the above films or layers has a transmittance of 10% to 90% of ultraviolet light with a wavelength of 320 nm.

[0041] (phase contrast layer) The phase difference layer 31 may consist of one layer having a phase difference, or it may consist of two or more layers. If it consists of two or more layers, they may be positive A plates or positive C plates such as λ / 4 plates or λ / 2 plates. If it includes a positive C plate, the positive C plate may be stacked on the side closer to the polarizer layer 23, or on the side farther from the polarizer layer 23.

[0042] One method for forming the phase difference layer 31 is to first form an alignment film and then apply the polymerizable liquid crystal compound constituting the phase difference layer 31 on top of it. If there are two or more layers having a phase difference, the separately formed phase difference layers can be bonded together with an ultraviolet-curing adhesive. Depending on the type of phase difference layer to be formed, a horizontal alignment film or a vertical alignment film is used. A horizontal alignment film is an alignment film that has an alignment restricting force to align the polymerizable liquid crystal compound constituting the phase difference layer in the horizontal direction, while a vertical alignment film is an alignment film that has an alignment restricting force to align the polymerizable liquid crystal compound constituting the phase difference layer in the vertical direction.

[0043] The thickness of the phase difference layer 31 is, for example, 0.1 μm to 10 μm, preferably 0.5 μm to 8 μm, and more preferably 1 μm to 6 μm.

[0044] (Light transmittance of the second optical film) With respect to the light transmittance of the second optical film 3, it is preferable that the second optical film 3 comprising each of the above-mentioned films or layers has a transmittance of less than 10% of ultraviolet light with a wavelength of 320 nm.

[0045] (adhesive layer) The adhesive forming the adhesive layer 4 preferably contains an epoxy compound that does not contain an aromatic ring in its molecule, from the viewpoint of weather resistance, refractive index, cationic polymerizability, etc. The adhesive may also contain a radical polymerizable compound such as a compound having a (meth)acryloyl group. Furthermore, the adhesive is preferably an active energy ray curing adhesive that hardens upon irradiation with active energy rays (ultraviolet rays or heat rays).

[0046] Preferred epoxy compounds include, for example, hydrogenated epoxy compounds, alicyclic epoxy compounds, and aliphatic epoxy compounds. A polymerization initiator (for example, a photocationic polymerization initiator for polymerization by ultraviolet irradiation, or a thermal cationic polymerization initiator for polymerization by heat irradiation) and other additives (such as sensitizers) can be added to the epoxy compound to prepare a coating composition for use.

[0047] Alternatively, a water-based adhesive containing polyvinyl alcohol-based resin can be used as the adhesive.

[0048] The thickness of the adhesive layer 4 is preferably 0.1 μm to 5 μm, and more preferably 0.5 μm to 3 μm.

[0049] <Method for manufacturing laminated optical films> As shown in Figures 3 and 4, the manufacturing method for the laminated optical films 1A and 1B involves introducing the first optical film 2A, the adhesive layer 4, and the second optical film 3 between a pair of rotating laminating rolls 6a and 6b, arranged in that order in the direction connecting the laminating rolls 6a and 6b, and laminating the first optical film 2A and the second optical film 3 (laminating step). During lamination, the polarizer layer (second optical functional layer) 23 side of the first optical film 2A faces the adhesive layer 4 side. After lamination, ultraviolet light is irradiated from an ultraviolet irradiation device 7 to cure the adhesive layer 4 and obtain the laminated optical film 1A. Subsequently, the release substrate film 21 is peeled off while the laminated optical film 1A is being transported to obtain the laminated optical film 1B. The laminated optical film 1B is then transported so that the transport rolls do not come into contact with the surface from which the release substrate film 21 was peeled off (transportation step). The following describes each step of this manufacturing method.

[0050] The first optical film 2A and the second optical film 3 are manufactured separately and transported to a lamination roll 6a and 6b where they are joined. Upstream of the lamination rolls 6a and 6b, a coating machine 5 is positioned to apply adhesive to the phase difference layer 31 of the second optical film 3.

[0051] The manner in which each film or layer exists during lamination will now be explained. As shown in Figure 4, the widths of each film or layer between the lamination rolls 6a and 6b satisfy the following relationship. In the following relationship, in the first optical film 2A, the width of the release substrate film 21 and the width of the hard coat layer 22 are equal, so the width of the hard coat layer 22 (W3) is equivalent to the width of the first optical film 2A. Also, in the second optical film 3, the width of the release substrate film 32 and the width of the phase difference layer 31 are equal, so the width of the phase difference layer 31 (W4) is equivalent to the width of the second optical film 3. • The width W2 of the adhesive layer 4 is smaller than the width W1 of the polarizer layer 23. (W2 <W1) The width W2 of the adhesive layer 4 is smaller than the width W4 of the phase difference layer 31. (W2 <W4) The polarizer layer 23 and the phase difference layer 31 are positioned to encompass the width W2 of the adhesive layer 4.

[0052] Here, "internal" means that both ends of the wider member are located further outward in the width direction than both ends of the narrower member.

[0053] Furthermore, while not a mandatory requirement during lamination, the following relationships are also met. The width W1 of the polarizer layer 23 is smaller than the width W3 of the hard coat layer 22. (W1 <W3) The hard coat layer 22 is positioned to encompass the width W1 of the polarizer layer 23. The width W4 of the phase difference layer 31 is greater than the width W3 of the hard coat layer 22. (W4 > W3) • Width (W) of a pair of adhesive rolls 6a, 6b R1 ,W R2 ) are equal to each other. (W R1 =W R2 ) • Width (W) of a pair of adhesive rolls 6a, 6b R1 ,W R2 ) is greater than the width (W3) of the first optical film 2A and the width (W4) of the second optical film 3. (W R1 >W3, W R1>W4, W R2 >W3, W R2 >W4) · The pair of bonding rolls 6a and 6b are positioned so as to enclose the existing width (W3) of the first optical film 2A and the existing width (W4) of the second optical film 3.

[0054] Here, the "width of the bonding roll" means the total width of the portion that extends while maintaining the same diameter as the effective contact surface that contributes to bonding. For example, when there is a portion on the end side of the bonding rolls 6a and 6b where a part in the width direction has a reduced diameter and does not contact the first optical film 2A or the second optical film 3, the width of the portion excluding the reduced diameter part is taken as the total width of the bonding rolls 6a and 6b.

[0055] Also, as the dimensional difference in the width direction at the ends of each film or each layer, it is preferable that the following distance between the ends (horizontal distance) is as shown below. The distance between the ends shown below is half of the difference in the widths of each film or each layer when the central axes of each film or each layer are aligned. · Horizontal distance between the end of the hard coat layer 22 and the end of the polarizer layer 23 = 0.1 mm to 50 mm · Horizontal distance between the end of the polarizer layer 23 and the end of the adhesive layer 4 = 0.1 mm to 50 mm · Horizontal distance between the end of the retardation layer 31 and the end of the hard coat layer 22 = 0 mm to 50 mm

[0056] Note that the above values are shown as the distance between the ends during bonding, but it is preferable that the laminated optical film 1 shown in FIG. 1 also has a similar distance between the ends.

[0057] The laminate 8 formed by bonding on the bonding rolls 6a and 6b is in an uncured state of adhesive. Subsequently, when ultraviolet light is irradiated onto the laminate that has passed through the bonding rolls 6a and 6b from an ultraviolet irradiation device 7 located downstream of the bonding rolls 6a and 6b, the adhesive hardens and becomes the laminated optical film 1A shown in Figure 1 (curing process). Here, when the ultraviolet light transmittance of the first optical film 2A and the second optical film 3 satisfies the above value, it is preferable to irradiate from the first optical film 2A side.

[0058] The amount of ultraviolet radiation (integrated light in the UVA region (320-390 nm)) was 150 mJ / cm². 2 ~800 mJ / cm 2 It is preferable to irradiate in such a manner. The irradiation with ultraviolet light may be carried out in multiple stages, taking into consideration the degree of curing of the adhesive and the time required for curing. The ultraviolet light source is not particularly limited, but ultraviolet light having an emission distribution of wavelengths of 400 nm or less can be used, such as low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, metal halide lamps, etc.

[0059] Subsequently, while conveying the laminated optical film 1A, the release substrate film 21 is peeled off from the laminated optical film 1A to obtain the laminated optical film 1B. The laminated optical film 1B is then conveyed in such a way that the conveyor roll does not come into contact with the surface from which the release substrate film 21 was peeled off.

[0060] Here, the laminated optical film 1B (Figure 2) is a long film comprising, in this order, a hard coat layer 22 as the outermost layer, a polarizer layer 23, an adhesive layer 4, and a phase difference layer 31. The laminated optical film 1B maintains the width relationship of each component in the direction perpendicular to the transport direction, as described above during lamination. That is, the width of the adhesive layer 4 is smaller than the width of the polarizer layer 23 and also smaller than the width of the phase difference layer 3. Furthermore, the polarizer layer 23 and the phase difference layer 3 are positioned so as to encompass the width of the adhesive layer 4. During the transport of the laminated optical film 1B, the transport rolls do not come into contact with the hard coat layer 22, which is exposed as the outermost layer.

[0061] (effect) The manufactured laminated optical film 1B may subsequently undergo further film lamination or film delamination operations. For example, a protective film may be laminated onto the surface of the hard coat layer 22 exposed by peeling off the release substrate film 21. The protective film may be peelable from the hard coat layer 22.

[0062] Even when a liquid crystal coated polarizer is used as the polarizer in this embodiment, edge flaps 10 are generated when the laminated optical film 1B is formed, similar to the conventional method for manufacturing laminated optical films (Figure 2). That is, if the width of the adhesive layer 4 is less than or equal to the width of the polarizer layer 23, the portion of the hard coat layer 22, polarizer layer 23, and overcoat layer 24 that constitute the first optical film 2B remaining after the release substrate film 21 is peeled off, which extends beyond the width of the adhesive layer 4, becomes a free edge (edge ​​flaps 10). Since the edge flaps 10 are not fixed and move during transport, they are prone to tearing and becoming scraps during transport. The thinner the edge flaps 10 are, the more easily they tear, and this tendency becomes more pronounced when the total thickness of the hard coat layer 22, polarizer layer 23, and overcoat layer 24 is thin. According to the inventors' studies, when a liquid crystal coated polarizer is used, the polarizer layer 23 is particularly thin, so it was found that after the release substrate film 21 is peeled off, the edge flaps 10 tear into small pieces and contaminate the transport line.

[0063] In the manufacturing method of the present embodiment, in the conveying step of conveying the laminated optical film 1B, the laminated optical film 1B is conveyed so as not to contact the conveying roll with the exposed surface of the hard coat layer 22. Therefore, even when the end whiskers 10 are present, the end whiskers 10 are suppressed from being torn off. Therefore, according to the manufacturing method of the present embodiment, even when a liquid crystal coating type polarizer is adopted as the polarizer, the conveying line is not contaminated by the cut end of the film during the conveyance of the laminated optical film. In addition, when another film or layer (for example, the above-mentioned protective film) is laminated on the surface of the hard coat layer 22 thereafter, the end whiskers are fixed to the layer and do not move. Therefore, even if the conveying roll contacts the side of the layer, the end whiskers are not torn off.

[0064] As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments. For example, in the above embodiment, the aspect including the overcoat layer 24 is shown. However, an aspect not including the overcoat layer 24 may be adopted, or other layers may be provided instead. Further, in the above embodiment, the aspect in which the width W1 of the polarizer layer 23 is smaller than the width W3 of the hard coat layer 22 (W1 < W3) at the time of bonding is shown. However, these widths may be substantially equal. Further, the first optical film 2A may have both ends trimmed before being introduced into the bonding rolls 6a and 6b so that the widths of all of the release base film 21, the hard coat layer 22, the polarizer layer 23, and the overcoat layer 24 are equal.

[0065] Further, in the above embodiment, after obtaining the laminated optical film 1A, the release base film 21 is peeled off immediately on the same conveying line (FIG. 3). However, the laminated optical film 1A may be once wound into a roll. Thereafter, after feeding out the wound laminated optical film 1A, the release base film 21 is peeled off, and the laminated optical film 1B is conveyed. The conveyance at this time may be performed on another conveyance line.

Industrial Applicability

[0066] The present invention can be used in a method for manufacturing a polarizing plate including a liquid crystal coating type polarizer. [Explanation of Symbols]

[0067] 1A,1B...Laminated optical film, 2A,2B...First optical film, 3...Second optical film, 4...Adhesive layer, 5...Coating machine, 6a,6b...Laminating roll, 7...UV irradiation device, 8...Laminate, 10...Edge leaf, 21...Release substrate film, 22...Hard coat layer (first optical functional layer), 23...Polarizer layer (second optical functional layer), 24...Overcoat layer, 31...Phase difference layer (third optical functional layer), 32...Release substrate film, W1...Width of polarizer layer, W2...Width of adhesive layer, W3...Width of hard coat layer, W4...Width of phase difference layer, W R1 ,W R2 ...width of the laminating roll.

Claims

1. A method for manufacturing a laminated optical film, comprising: a lamination step of introducing a first optical film, an adhesive layer, and a second optical film between a pair of rotating lamination rolls in the order indicated in the direction connecting the pair of lamination rolls, thereby laminating the first optical film and the second optical film to obtain a laminated optical film; and a transport step of transporting the laminated optical film, The first optical film comprises a release substrate film, a first optical functional layer, and a second optical functional layer in this order. The second optical functional layer is a polarizer layer containing a liquid crystal coated polarizer, During the bonding process described above, The first optical film has the second optical functional layer side facing the adhesive layer side. The width of the adhesive layer is smaller than the width of the second optical functional layer and smaller than the width of the second optical film. The second optical functional layer and the second optical film are positioned to encompass the width of the adhesive layer. The width of the second optical functional layer is smaller than the width of the first optical functional layer. The first optical functional layer is positioned to encompass the width of the second optical functional layer. In the aforementioned transport process, The release substrate film is peeled off from the laminated optical film that has passed between the pair of laminating rolls. A manufacturing method comprising the following steps: after peeling off the release substrate film, the film is transported without the transport roll coming into contact with the first optical film.

2. The manufacturing method according to claim 1, wherein the thickness of the portion of the first optical film excluding the release substrate film is 1 μm to 10 μm.

3. The width of the pair of laminating rolls is greater than the width of either the first optical film or the second optical film. The manufacturing method according to claim 1 or 2, wherein the pair of laminating rolls are positioned to encompass the width of the first optical film and the second optical film.

4. The method for producing the liquid crystal coated polarizer according to any one of claims 1 to 3, wherein the liquid crystal coated polarizer is a cured product of a polymerizable liquid crystal composition comprising a dichroic dye and a polymerizable liquid crystal compound having at least one polymerizable group.

5. The manufacturing method according to any one of claims 1 to 4, wherein the first optical functional layer is a hard coat layer.

6. The manufacturing method according to any one of claims 1 to 5, wherein the first optical film further comprises an overcoat layer coated on the second optical functional layer.

7. The second optical film consists of multiple layers, The manufacturing method according to any one of claims 1 to 6, wherein the plurality of layers include a phase difference layer.

8. The aforementioned adhesive is an active energy ray curing type adhesive, The manufacturing method according to any one of claims 1 to 7, further comprising a curing step of curing the adhesive by irradiating the laminate that has passed between the pair of laminating rolls with active energy rays.

9. A method for transporting a long laminated optical film comprising a hard coat layer, a polarizer layer, an adhesive layer, and a phase difference layer in this order, Regarding the width in the direction perpendicular to the conveying direction, The width of the adhesive layer is smaller than the width of the polarizer layer and smaller than the width of the phase difference layer. The polarizer layer and the phase difference layer are positioned to encompass the width of the adhesive layer. The width of the polarizer layer is smaller than the width of the hard coat layer. The hard coat layer is positioned to encompass the width of the polarizer layer, The aforementioned hard coat layer is the outermost layer, A transport method for transporting a laminated optical film without the transport roll coming into contact with the hard coat layer.

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