Method for manufacturing multilayer optical film

Abstract

This method for manufacturing a multilayer optical film includes: a radiation step of radiating active energy rays onto a coated surface of a radically polymerizable curable composition on a first optical film to cure at least a part of the radically polymerizable curable composition, thereby producing a first optical film with a functional layer, the functional layer being laminated on the first optical film; a bonding step of bonding a functional layer surface of the first optical film with the functional layer to an adhesive composition coated surface of a second optical film; and an adhesion step of radiating active energy rays from a side of the first optical film with the functional layer or from a side of the second optical film to cure at least the adhesive composition and form an adhesive layer, thereby causing the first optical film with the functional layer to adhere to the second optical film via the adhesive layer.

Description

Manufacturing method for laminated optical films

[0001] This invention relates to a method for manufacturing a laminated optical film. The laminated optical film manufactured by this method can be used to form image display devices such as mobile phones, car navigation systems, personal computer monitors, and televisions.

[0002] Image display devices such as mobile phones, car navigation systems, computer monitors, and televisions are equipped with laminated optical films in which multiple optical films are laminated with adhesive or tack layers in between. Transparent resin films such as phase difference films, polarizers, and transparent protective films are used as optical films.

[0003] In recent years, there has been a strong demand for improved functionality, such as durability, for laminated optical films and the various optical films that constitute them. For example, Patent Document 1 below describes an optical laminate having a polarizer containing a polyvinyl alcohol-based resin and a phase difference body containing a cured polymerizable liquid crystal compound, wherein the optical laminate has a first adhesive layer provided in contact with the polarizer and a second adhesive layer provided in contact with the phase difference body between the polarizer and the phase difference body.

[0004] Japanese Patent Publication No. 2022-110684

[0005] As a result of diligent research by the present inventors, it has been found that the technology described in Patent Document 1 above has room for further improvement in terms of improving the functionality of the laminated optical film and the various optical films that constitute the laminated optical film.

[0006] In recent years, there has been a strong desire to manufacture laminated optical films with superior functionality and various optical films that constitute laminated optical films with high productivity, but the technology described in Patent Document 1 above does not adequately address this point.

[0007] This invention was developed in view of the above circumstances, and aims to provide a method for manufacturing laminated optical films that offers excellent productivity and can impart superior functionality.

[0008] The above problem can be solved by the following configuration. That is, the present invention relates to a method for manufacturing a laminated optical film in which at least a first optical film and a second optical film are laminated via an adhesive layer, wherein the adhesive layer is a cured layer of an adhesive composition, and the method for manufacturing a laminated optical film (1) includes: a first coating step of coating the first optical film with a radical polymerizable curable composition; a second coating step of coating the second optical film with the adhesive composition; an irradiation step of irradiating the coated surface of the first optical film with the radical polymerizable curable composition with active energy rays to cure at least a portion of the radical polymerizable curable composition, thereby manufacturing a first optical film with a functional layer laminated on the first optical film; a bonding step of bonding the functional layer surface of the first optical film with a functional layer and the coated surface of the second optical film with the adhesive composition; and an adhesion step of bonding the first optical film with a functional layer and the second optical film via an adhesive layer formed by irradiating from the side of the first optical film with a functional layer or the side of the second optical film with active energy rays to cure at least the adhesive composition.

[0009] In the above-described method for manufacturing a laminated optical film (1), the irradiation step is preferably a method for manufacturing a laminated optical film (2) in which the irradiation step is irradiated with the coated surface of the first optical film with the radical polymerizable curable composition using a UV-LED as the active energy ray, the light source having a maximum emission wavelength in the wavelength range of 280 to 420 nm.

[0010] In the above-described method for manufacturing a laminated optical film (1) or (2), the irradiation conditions of the UV-LED are 500 to 3000 mW / cm². ２ Illuminance range of 250-3000 mJ / cm ２ A method for manufacturing a laminated optical film within the light intensity range (3) is preferred.

[0011] In any of the above methods (1) to (3) for manufacturing a laminated optical film, method (4) is preferred, in which, in the first coating step of coating the first optical film with a radical polymerizable curable composition, the coating thickness when coating the first optical film with the radical polymerizable curable composition is less than 5 μm.

[0012] In any of the above methods (1) to (4) for manufacturing a laminated optical film, method (5) is preferred, in which, in the second coating step of coating the second optical film with the adhesive composition, the coating thickness when coating the second optical film with the adhesive composition is less than 5 μm.

[0013] In any of the above methods (1) to (5) for manufacturing a laminated optical film, method (6) is preferred, wherein in the irradiation step, the uncured portion of the radical polymerizable curable composition is 20% by mass or less.

[0014] In any of the above methods (1) to (6) for manufacturing a laminated optical film, method (7) in which the first optical film is an iodine-based polarizer is preferred.

[0015] In the above-mentioned method for manufacturing a laminated optical film (7), the method for manufacturing a laminated optical film (8) in which the thickness of the iodine-based polarizer is 8 μm or less is preferred.

[0016] In any of the above methods (1) to (8) for manufacturing a laminated optical film, method (9) in which the second optical film is a liquid crystal phase difference film is preferred.

[0017] In the above-mentioned method for manufacturing a laminated optical film (9), a method for manufacturing a laminated optical film (10) in which the thickness of the phase difference film is 5 μm or less is preferred.

[0018] In the method for manufacturing a laminated optical film according to the present invention, a functional layered first optical film is manufactured by curing at least a portion of a radical polymerizable curable composition, thereby laminating a functional layer on a first optical film. By appropriately adjusting the composition of the radical polymerizable curable composition depending on the type of first optical film, the function of the first optical film in the laminated optical film can be improved. For example, if the first optical film is an iodine-based polarizer, by appropriately adjusting the composition of the radical polymerizable curable composition, a barrier function can be provided that suppresses the elution and diffusion of iodine from the iodine-based polarizer. Furthermore, in the method for manufacturing a laminated optical film according to the present invention, at least a portion of the radical polymerizable curable composition is cured in an irradiation step in which the coated surface of the radical polymerizable curable composition of the first optical film is irradiated with active energy rays. In other words, at least a portion of the radical polymerizable curable composition can be controlled to remain in an unreacted state. Furthermore, in the method for manufacturing a laminated optical film according to the present invention, an adhesive layer is formed on the functional layer side of the first optical film using a cured adhesive composition layer. At least a portion of the unreacted radical polymerizable curable composition becomes compatible with the coated adhesive composition during the bonding process, thus improving the adhesion at the interface between the functional layer of the first optical film and the adhesive layer. For this reason, the adhesion between the first optical film with the functional layer and the second optical film can be improved. The degree of curing of the radical polymerizable curable composition in the irradiation process can be adjusted, for example, by irradiating the light source with a UV-LED having a maximum emission wavelength in the wavelength range of 280 to 420 nm under arbitrary conditions as the active energy ray during the irradiation process.

[0019] Furthermore, in the method for manufacturing a laminated optical film according to the present invention, if the first optical film is an iodine-based polarizer, for example, a barrier function can be imparted to the iodine-based polarizer that suppresses the elution and diffusion of iodine from the iodine-based polarizer. The barrier function, which is one of the functions that can be imparted to an iodine-based polarizer, will be described below.

[0020] Image display devices equipped with iodine-based polarizers may be used under high temperature and high humidity conditions. For example, if a laminated optical film in which at least an iodine-based polarizer (first optical film) and a phase difference film (second optical film) are laminated via an adhesive layer is incorporated into an image display device and exposed to high temperature and high humidity conditions, the iodine in the iodine-based polarizer may penetrate the adhesive layer and the phase difference film, either alone or via water, and eventually reach, for example, the panel or sensor of the image display device beyond the phase difference film, causing corrosion. As a result, the panel or sensor of the image display device may deteriorate, or the image display function may be significantly impaired. However, an optical film with a functional layer (in this specification, when the optical film is an iodine-based polarizer, it may be referred to as an "iodine-based polarizer with a barrier functional layer") manufactured by the method for manufacturing a laminated optical film according to the present invention has a functional layer (in this specification, it may be referred to as a "barrier functional layer") that exhibits a barrier function that significantly inhibits the movement of iodine. Therefore, iodine does not reach the panel or sensor of the image display device, and remains inside the polarizer. As a result, even when an image display device incorporating an iodine-based polarizer with a barrier layer is used under high temperature and high humidity conditions, corrosion of the panel or sensor of the image display device by iodine can be sufficiently prevented.

[0021] This figure shows an example of an image display device incorporating a laminated optical film equipped with an iodine-based polarizer with a barrier function layer, manufactured by the method for manufacturing a laminated optical film according to the present invention.

[0022] The present invention relates to a method for manufacturing a laminated optical film in which a first optical film with a functional layer and a second optical film are laminated via an adhesive layer. The first optical film on which the functional layer is provided is not particularly limited and can be, for example, an iodine-based polarizer, a phase difference film, a liquid crystal phase difference film, or a transparent protective film. In the present invention, when the first optical film is an iodine-based polarizer, it is preferable because it can provide the iodine-based polarizer with a barrier function that suppresses the elution and diffusion of iodine from the iodine-based polarizer.

[0023] <Iodine-based polarizers> In the present invention, iodine-based polarizers are not particularly limited and various types can be used. Examples of iodine-based polarizers include hydrophilic polymer films such as polyvinyl alcohol-based films, partially formalized polyvinyl alcohol-based films, and partially saponified ethylene-vinyl acetate copolymer films, to which iodine is adsorbed and then uniaxially stretched. The thickness of the polarizer can be, for example, 3 to 20 μm.

[0024] However, in this invention, from the viewpoint of improving heat resistance in harsh environments at high temperatures, it is preferable to use a thin polarizer with a thickness of 3 μm or more and 15 μm or less as the iodine-based polarizer. It is particularly preferable that the thickness be 12 μm or less, even more preferably 10 μm or less, and especially preferably 8 μm or less. Such thin polarizers have less thickness variation, excellent visibility, and excellent resistance to thermal shock due to minimal dimensional change.

[0025] Iodine-based polarizers, made by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching it, can be produced, for example, by dyeing the polyvinyl alcohol by immersing it in an aqueous solution of iodine and stretching it to 3 to 7 times its original length. Boric acid, zinc sulfate, zinc chloride, etc., may be included as needed, or the film may be immersed in an aqueous solution of potassium iodide, etc. Furthermore, if necessary, the polyvinyl alcohol-based film may be immersed in water and washed before dyeing. Washing the polyvinyl alcohol-based film with water removes dirt and anti-blocking agents from the film surface, and also prevents uneven dyeing by swelling the film. Stretching may be performed after dyeing with iodine, while dyeing, or after stretching. Stretching can also be performed in aqueous solutions of boric acid or potassium iodide, or even in a water bath.

[0026] Examples of thin iodine-based polarizers include thin polarizers described in Japanese Patent No. 4751486, Japanese Patent No. 4751481, Japanese Patent No. 4815544, Japanese Patent No. 5048120, International Publication No. 2014 / 077599, International Publication No. 2014 / 077636, etc., or thin polarizers obtained from the manufacturing methods described therein.

[0027] As for the thin polarizers, among manufacturing methods that include a step of stretching in a laminated state and a step of dyeing, those obtained by a manufacturing method that includes a step of stretching in a boric acid aqueous solution, as described in Japanese Patent No. 4751486, Japanese Patent No. 4751481, and Japanese Patent No. 4815544, are preferred because they can be stretched to a high magnification and their polarization performance can be improved. In particular, those obtained by a manufacturing method that includes a step of auxiliary air stretching before stretching in a boric acid aqueous solution, as described in Japanese Patent No. 4751481 and Japanese Patent No. 4815544, are preferred. These thin polarizers can be obtained by a manufacturing method that includes a step of stretching a polyvinyl alcohol-based resin (hereinafter also referred to as PVA-based resin) layer and a stretching resin substrate in a laminated state and a step of dyeing. With this manufacturing method, even if the PVA-based resin layer is thin, it is possible to stretch it without problems such as breakage due to stretching because it is supported by the stretching resin substrate.

[0028] The functional layer side of the iodine-based polarizer (the coated surface of the radically polymerizable curable composition) may be subjected to surface modification treatment before the formation of the functional layer. Examples of surface modification treatments include corona treatment, plasma treatment, and itro treatment, with corona treatment being particularly preferred. Corona treatment generates reactive functional groups such as carbonyl groups and amino groups on the polarizer surface, improving adhesion to the adhesive layer. In addition, the ashing effect removes foreign matter from the surface and reduces surface irregularities, making it possible to manufacture a laminated optical film with excellent appearance characteristics.

[0029] Also, on the surface on the functional layer side of the iodine-based polarizer (the coating surface of the radically polymerizable curable composition), an easy-adhesion layer may be formed by coating an easy-adhesion composition. Examples of the easy-adhesion composition include an aqueous solution containing a monofunctional radically polymerizable compound represented by the general formula (2) below, which is also a compound that can be blended into the radically polymerizable curable composition.

[0030] In the method for producing the laminated optical film according to the present invention, when the first optical film is an iodine-based polarizer, the second optical film laminated with the iodine-based polarizer is preferably a retardation film. However, the retardation film may be, for example, a retardation film provided with an easy-adhesion layer on the adhesive layer side, or a retardation film subjected to a surface modification treatment such as corona treatment on the adhesive layer side. The easy-adhesion layer and the surface modification treatment may be the same as those for the polarizer. Also, it may be a retardation film laminated with an acrylic film, a polycarbonate film, a triacetyl cellulose (TAC) film, a cycloolefin polymer film, etc. on the adhesive layer side. The retardation film will be described below.

[0031] <Retardation film> Examples of the retardation film include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, an alignment film of a liquid crystal polymer, and a film supporting an alignment layer of a liquid crystal polymer. The thickness of the film constituting the retardation film is not particularly limited, but is generally about 1 to 150 μm.

[0032] As the retardation film, the following formulas (1) to (3): 0.70 < Re

[450] / Re

[550] < 0.97... (1) 1.5×10 －３ <Δn<6×10 －３... (2) 1.13 < NZ < 1.50 ... (3) (wherein Re

[450] and Re

[550] are the in-plane phase difference values ​​of the phase difference film measured with light of wavelengths of 450 nm and 550 nm at 23°C, respectively; Δn is the in-plane birefringence nx-ny when the refractive indices in the slow phase axis direction and the fast phase axis direction of the phase difference film are nx and ny, respectively; and NZ is the ratio of the thickness-direction birefringence nx-nz to the in-plane birefringence nx-ny when nz is the refractive index in the thickness direction of the phase difference film) an inverse wavelength-dispersive type phase difference film that satisfies this condition may also be used.

[0033] When the laminated optical film according to the present invention includes a phase difference film as the second optical film, a liquid crystal phase difference film is preferred. Liquid crystal phase difference films are generally thin, for example, 5 μm or less in thickness. However, as mentioned above, even when the laminated optical film is exposed to high temperature and high humidity, the iodine contained in the iodine-based polarizer remains within the polarizer due to the barrier function of the adhesive layer. Therefore, even a thin liquid crystal phase difference film can sufficiently prevent corrosion of the panel or sensor of the image display device. When forming a liquid crystal phase difference film, a liquid crystalline compound is preferably used, and a solvent containing the liquid crystalline compound can be applied to the substrate using, for example, a wire bar, gap coater, comma coater, gravure coater, or slot die. In this case, the applied liquid crystalline solution may be air-dried or heat-dried. It is preferable that the liquid crystalline solution be applied at a concentration lower than the isotropic phase-liquid crystal phase transition concentration, i.e., in an isotropic phase state. In this case, it can be stably oriented by methods such as rubbing or photo-alignment.

[0034] <Transparent protective film> In the present invention, as a material constituting a transparent protective film that can be used as the first optical film on which a functional layer is laminated, or that can constitute a laminated optical film by being used in combination with an iodine-based polarizer (used as the second optical film), for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, etc. is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, cyclic polyolefin resins (norbornene-based resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The transparent protective film may contain one or more arbitrary appropriate additives. Examples of the additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, colorants, etc. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. When the content of the thermoplastic resin in the transparent protective film is 50% by weight or less, there is a possibility that the high transparency and the like inherent in the thermoplastic resin cannot be sufficiently exhibited.

[0035] Also, as a material for forming the transparent protective film, those excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, etc. are preferable, and particularly, the moisture permeability is 150 g / m ２ / 24 h or less is more preferable, 140 g / m ２ / 24 h or less is particularly preferable, and 120 g / m ２ / 24 h or less is even more preferable.

[0036] The transparent protective film may be provided with functional layers such as a hard coat layer, an anti-reflective layer, an anti-sticking layer, a diffusion layer, or an anti-glare layer. These functional layers, such as the hard coat layer, anti-reflective layer, anti-sticking layer, diffusion layer, and anti-glare layer, can be provided on the transparent protective film itself, or they can be provided separately from the transparent protective film.

[0037] The thickness of the transparent protective film can be determined as appropriate, but generally it is about 1 to 500 μm, preferably 1 to 300 μm, and more preferably 5 to 200 μm, considering factors such as strength, workability, and thinness. Furthermore, 10 to 200 μm is preferred, and 20 to 80 μm is preferred.

[0038] The method for manufacturing a laminated optical film according to the present invention includes: a first coating step of coating a first optical film with a radical polymerizable curable composition; a second coating step of coating a second optical film with the adhesive composition; an irradiation step of irradiating the coated surface of the first optical film with the radical polymerizable curable composition with active energy rays to cure at least a portion of the radical polymerizable curable composition, thereby manufacturing a first optical film with a functional layer laminated on the first optical film; a bonding step of bonding the functional layer surface of the first optical film with the functional layer and the coated surface of the adhesive composition of the second optical film; and an adhesion step of bonding the first optical film with the functional layer and the second optical film via an adhesive layer formed by irradiating from the side of the first optical film with the functional layer or the side of the second optical film with active energy rays to cure at least the adhesive composition. Each step will be described below. Steps other than the coating step and the irradiation step will be described later.

[0039] (First and Second Coating Processes) In the first and second coating processes, a radical polymerizable curable composition or adhesive composition capable of imparting various functions is coated onto the optical film. The method for coating the first optical film with the radical polymerizable curable composition, and further, the method for coating the second optical film with the adhesive composition, is appropriately selected depending on the viscosity of the composition and the desired thickness. Examples include reverse coaters, gravure coaters (direct, reverse, and offset), bar reverse coaters, roll coaters, die coaters, bar coaters, and rod coaters. The viscosity of the radical polymerizable curable composition and the adhesive composition is preferably 0.5 to 100 mPa·s. If the viscosity of the radical polymerizable curable composition and the adhesive composition is high, the surface smoothness after coating is poor and an appearance defect occurs, which is undesirable. For this reason, each composition can be heated or cooled to adjust the viscosity to a preferred range before application. When coating the first optical film with the radical polymerizable curable composition, the coating thickness is preferably less than 5 μm. Furthermore, when applying the adhesive composition to the second optical film, the coating thickness is preferably less than 5 μm, and more preferably less than 2 μm.

[0040] (Irradiation Process) In the irradiation process, the coated surface of the radical polymerizable curable composition of the first optical film is irradiated with active energy rays to cure at least a portion of the radical polymerizable curable composition, thereby producing a first optical film with a functional layer laminated on the first optical film. The irradiation direction of the active energy rays (electron beam, ultraviolet light, visible light, etc.) can be any appropriate direction.

[0041] In the irradiation step, when irradiating the coating surface of the radical-polymerizable curable composition of the first optical film with an active energy ray using a UV-LED having a maximum emission wavelength in the wavelength range of 280 to 420 nm as the light source, it is preferable because the thermal influence on the first optical film during irradiation can be reduced. In addition, in the irradiation step, while reducing thermal damage to the first optical film, etc., the degree of curing of the radical-polymerizable curable composition can be easily controlled. Therefore, when forming an adhesive layer with a cured product layer of an adhesive composition on the functional layer side of the first optical film, at least a part of the unreacted radical-polymerizable curable composition is compatible with the applied adhesive composition, and the adhesion at the interface can be improved. For this reason, the adhesion between the first optical film with a functional layer and the second optical film can be improved.

[0042] In the method for manufacturing a laminated optical film according to the present invention, in the first coating step, a radical-polymerizable curable composition is applied to the first optical film, and in the irradiation step, the coating surface of the radical-polymerizable curable composition of the first optical film is irradiated with an active energy ray to cure at least a part of the radical-polymerizable curable composition, thereby manufacturing a first optical film with a functional layer in which a functional layer is laminated on the first optical film. The radical-polymerizable curable composition will be described below.

[0043] In the present invention, in the radical-polymerizable curable composition, as a photoinitiator, a compound represented by the following general formula (1);

[0044] (In the formula, R １ and R ２ represent -H, -CH ２ CH ３ , -iPr or Cl, and R １ and R ２ may be the same or different). Among the compounds represented by the general formula (1), R １ and R ２ are -CH ２ CH ３Diethylthioxanthone is particularly preferred. The blending ratio of the compound represented by general formula (1) in the radical polymerizable curable composition is preferably 0.5 to 5 parts by mass, and more preferably 1 to 3.5 parts by mass, based on 100 parts by mass of the total amount of curable components.

[0045] Polymerizable components that can be incorporated into radical polymerizable compositions include electron beam curable, ultraviolet curable, and visible light curable radical polymerizable compounds. In this invention, active energy rays with a wavelength range of 10 nm to less than 380 nm are denoted as ultraviolet rays, and active energy rays with a wavelength range of 380 nm to 800 nm are denoted as visible light.

[0046] Furthermore, in the method for manufacturing a laminated optical film according to the present invention, if the first optical film is an iodine-based polarizer, for example, a barrier function can be imparted to the iodine-based polarizer that suppresses the elution and diffusion of iodine from the iodine-based polarizer. When imparting a barrier function to an iodine-based polarizer, it is preferable to incorporate (meth)acrylate (A), which has a cyclic hydrocarbon skeleton in its molecule, as a curable component in the radical polymerizable curable composition.

[0047] (Meth)acrylate (A) having a cyclic hydrocarbon skeleton is, for example, a (meth)acrylate having an alicyclic skeleton, and due to having a cyclic hydrocarbon skeleton, it can form a barrier functional layer with low mobility and low ion permeability. Therefore, by incorporating (meth)acrylate (A) having a cyclic hydrocarbon skeleton in its molecule as a curable component in a radical polymerizable curable composition, the movement of iodine from an iodine-based polarizer can be retained in the barrier functional layer. As a result, even when an image display device incorporating an iodine-based polarizer is used under high temperature and high humidity conditions, corrosion of the panel or sensor of the image display device by iodine can be sufficiently prevented. As for (meth)acrylate (A), a compound having 5 to 12 carbon atoms constituting the cyclic hydrocarbon skeleton in its molecule is preferable because it can more reliably retain the movement of iodine from an iodine-based polarizer in the barrier functional layer.

[0048] When a (meth)acrylate (A) having a cyclic hydrocarbon skeleton is used, it is preferable because the movement of iodine from the iodine-based polarizer can be more reliably retained in the barrier functional layer. Examples of bifunctional (meth)acrylates include the compound described in formula (A1) below, which will be described later.

[0049] (Meth)acrylate (A) having a cyclic hydrocarbon skeleton is given by the following formulas (A1) to (A5): It is preferable to use at least one compound selected from the group consisting of the compounds described in [reference] because it can more reliably retain the movement of iodine from the iodine-based polarizer within the barrier functional layer.

[0050] In order to effectively exert the barrier function against iodine in the barrier functional layer, it is preferable that the radical polymerizable curable composition contains 70 parts by mass or more of (meth)acrylate (A) having a cyclic hydrocarbon skeleton in its molecule, when the total amount of curable components in the radical polymerizable curable composition is 100 parts by mass. More preferably, it is 80 parts by mass or more, and even more preferably 85 parts by mass or more.

[0051] When forming a barrier functional layer on an iodine-based polarizer, it is preferable that the radical polymerizable curable composition contains, as a polymerizable component, (meth)acrylate (A) having a cyclic hydrocarbon skeleton in its molecule, and further contains (meth)acrylate (B) containing a hydroxyl group. The (meth)acrylate (B) containing a hydroxyl group has the effect of enhancing the adhesion function of the barrier functional layer to the iodine-based polarizer. However, in order to achieve both the barrier function of the iodine-based polarizer and the adhesion function to the iodine-based polarizer, it is preferable that, when the total amount of curable components in the radical polymerizable curable composition is 100 parts by mass, the amount of (meth)acrylate (A) having a cyclic hydrocarbon skeleton in its molecule is 70 parts by mass or more, and furthermore, the content of (meth)acrylate (A) relative to (meth)acrylate (B) is designed to be within the range of 2 to 6 times. To achieve a better balance between the barrier function of iodine-based polarizers and the adhesion function with iodine-based polarizers, it is more preferable to use 5 to 25 parts by mass of (meth)acrylate (B) when the total amount of (meth)acrylate compound is 100 parts by mass.

[0052] Examples of hydroxyl group-containing (meth)acrylates (B) include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate; hydroxyl group-containing (meth)acrylates such as [4-(hydroxymethyl)cyclohexyl]methyl acrylate, cyclohexanedimethanol mono(meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate; and N-hydroxyalkyl group-containing (meth)acrylamide derivatives such as N-methylol (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, and N-methylol-N-propane (meth)acrylamide.

[0053] In the method for producing an optical film with a functional layer according to the present invention, when the optical film is an iodine-based polarizer, or when it is another optical film, such as a phase difference film, a liquid crystal phase difference film, or a transparent protective film, the radical polymerizable curable composition may further contain the radical polymerizable compounds shown below as curable components.

[0054] Radical polymerizable compounds include compounds having a radically polymerizable functional group of a carbon-carbon double bond, such as a (meth)acrylic group or a vinyl group. These monomer components can be either monofunctional radical polymerizable compounds or polyfunctional radical polymerizable compounds having two or more polymerizable functional groups. Furthermore, these radical polymerizable compounds can be used individually or in combination of two or more. Among these radical polymerizable compounds, compounds having a (meth)acrylic group are preferred, for example.

[0055] Examples of monofunctional radical polymerizable compounds include (meth)acrylic acid derivatives. Examples of (meth)acrylic acid derivatives include alkoxy group or phenoxy group-containing (meth)acrylates such as 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethyl carbitol (meth)acrylate, phenoxyethyl (meth)acrylate, alkylphenoxy polyethylene glycol (meth)acrylate; cyclohexyl (meth)acrylate, 4-tert-butylcyclohexyl acrylate, and cyclopentyl Examples include cycloalkyl (meth)acrylates such as (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; polycyclic (meth)acrylates such as 2-isobornyl (meth)acrylate, 2-norbornylmethyl (meth)acrylate, 5-norbornen-2-ylmethyl (meth)acrylate, 3-methyl-2-norbornylmethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and dicyclopentanyl (meth)acrylate; and others.

[0056] Other examples of monofunctional radical polymerizable compounds include various (meth)acrylic acid derivatives having a (meth)acryloyloxy group. Specifically, examples include alkyl esters of (meth)acrylic acid (with 1-20 carbon atoms), such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, 2-methyl-2-nitropropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, t-pentyl (meth)acrylate, 3-pentyl (meth)acrylate, 2,2-dimethylbutyl (meth)acrylate, n-hexyl (meth)acrylate, cetyl (meth)acrylate, n-octyl (meth)acrylate, lauryl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, and n-octadecyl (meth)acrylate.

[0057] Other monofunctional radical polymerizable compounds include, for example, (meth)acrylamide derivatives having a (meth)acrylamide group. Specific examples of (meth)acrylamide derivatives include, for example, N-alkyl group-containing (meth)acrylamide derivatives such as N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, and N-hexyl(meth)acrylamide; N-aminoalkyl group-containing (meth)acrylamide derivatives such as aminomethyl(meth)acrylamide and aminoethyl(meth)acrylamide; N-alkoxy group-containing (meth)acrylamide derivatives such as N-methoxymethylacrylamide and N-ethoxymethylacrylamide; and N-mercaptoalkyl group-containing (meth)acrylamide derivatives such as mercaptomethyl(meth)acrylamide and mercaptoethyl(meth)acrylamide. Furthermore, examples of heterocyclic (meth)acrylamide derivatives in which the nitrogen atom of the (meth)acrylamide group forms a heterocycle include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, and N-acryloylpyrrolidine.

[0058] Furthermore, monofunctional radical polymerizable compounds include epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate glycidyl ether; halogen-containing (meth)acrylates such as 2,2,2-trifluoroethyl (meth)acrylate, 2,2,2-trifluoroethyl ethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, and 3-chloro-2-hydroxypropyl (meth)acrylate; and dimethylaminoethyl (meth)acrylate, etc. Alkylaminoalkyl (meth)acrylates; oxetane group-containing (meth)acrylates such as 3-oxetanylmethyl (meth)acrylate, 3-methyl-oxetanylmethyl (meth)acrylate, 3-ethyl-oxetanylmethyl (meth)acrylate, 3-butyl-oxetanylmethyl (meth)acrylate, and 3-hexyl-oxetanylmethyl (meth)acrylate; heterocyclic (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate and butyrolactone (meth)acrylate; or hydroxypivalate neopentyl glycol (meth)acrylic acid adducts, p-phenylphenol (meth)acrylate, etc. may be used.

[0059] Furthermore, as monofunctional radical polymerizable compounds, carboxyl group-containing monomers such as (meth)acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid may be used.

[0060] Furthermore, as monofunctional radical polymerizable compounds, for example, lactam-based vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; and vinyl monomers having nitrogen-containing heterocyclic rings such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine may be used.

[0061] Furthermore, as the monofunctional radical polymerizable compound, a radical polymerizable compound having an active methylene group may be used. A radical polymerizable compound having an active methylene group is a compound that has an active double bond group such as a (meth)acrylic group at its terminal or in the molecule, and also has an active methylene group. Examples of active methylene groups include an acetoacetyl group, an alkoxymalonyl group, or a cyanoacetyl group. It is preferable that the active methylene group is an acetoacetyl group. Specific examples of radical polymerizable compounds having an active methylene group include acetoacetoxyalkyl (meth)acrylates such as 2-acetoacetoxyethyl (meth)acrylate, 2-acetoacetoxypropyl (meth)acrylate, and 2-acetoacetoxy-1-methylethyl (meth)acrylate; 2-ethoxymalonyloxyethyl (meth)acrylate, 2-cyanoacetoxyethyl (meth)acrylate, N-(2-cyanoacetoxyethyl)acrylamide, N-(2-propionylacetoxybutyl)acrylamide, N-(4-acetoacetoxymethylbenzyl)acrylamide, and N-(2-acetoacetylaminoethyl)acrylamide. The radical polymerizable compound having an active methylene group is preferably an acetoacetoxyalkyl (meth)acrylate.

[0062] Furthermore, in the present invention, the radical polymerizable curable composition contains the following general formula (2): A monofunctional radical polymerizable compound represented by (where X is a reactive group, Y is a C1-C12 alkylene group which may have a branched chain, or a phenylene group which may have a substituent, R １ and R ２ Each of these may independently represent a hydrogen atom, an aliphatic hydrocarbon group which may have substituents, an aryl group, or a heterocyclic group.

[0063] In the monofunctional radical polymerizable compound represented by general formula (2), the aliphatic hydrocarbon group may be a linear or branched alkyl group having 1 to 20 substituents, a cyclic alkyl group having 3 to 20 substituents, or an alkenyl group having 2 to 20 substituents. The aryl group may be a phenyl group having 6 to 20 substituents, a naphthyl group having 10 to 20 substituents, etc. The heterocyclic group may be a 5-membered or 6-membered ring containing at least one heteroatom and having substituents. These may be linked to each other to form a ring. In general formula (1), R １ and R ２ Preferably, the member is a hydrogen atom, a linear or branched alkyl group having 1 to 3 carbon atoms, and most preferably, a hydrogen atom.

[0064] X in the monofunctional radical polymerizable compound represented by general formula (2) is a reactive group, a functional group that can react with the curable component in the radical polymerizable curable composition, and examples include hydroxyl group, amino group, aldehyde group, carboxyl group, vinyl group, (meth)acrylic group, styryl group, (meth)acrylamide group, vinyl ether group, epoxy group, oxetane group, α,β-unsaturated carbonyl group, mercapto group, halogen group, etc. It is preferable that the reactive group X is at least one reactive group selected from the group consisting of vinyl group, (meth)acrylic group, styryl group, (meth)acrylamide group, vinyl ether group, epoxy group, oxetane group, and mercapto group. It is more preferable that the reactive group X is at least one reactive group selected from the group consisting of (meth)acrylic group, styryl group, and (meth)acrylamide group, and it is even more preferable when the monofunctional radical polymerizable compound represented by general formula (2) has a (meth)acrylamide group, as this increases the reactivity and the copolymerization rate with the curable component in the functional layer. Furthermore, the high polarity of the (meth)acrylamide group and its excellent adhesive properties make it preferable in that the effects of the present invention can be efficiently obtained.

[0065] Preferred specific examples of monofunctional radical polymerizable compounds represented by general formula (2) include the following compounds (2a) to (2d). Note that R in general formulas (2a) and (2b) ３ This is either a hydrogen atom or a methyl group.

[0066] Examples of monofunctional radical polymerizable compounds represented by general formula (2) include, in addition to the examples given above, esters of (meth)acrylates and boric acid, such as esters of hydroxyethyl acrylamide and boric acid, methylol acrylamide and boric acid, esters of hydroxyethyl acrylate and boric acid, and esters of hydroxybutyl acrylate and boric acid.

[0067] Examples of polyfunctional radical polymerizable compounds having two or more polymerizable functional groups include tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol diacrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol diacrylate, 2-ethyl-2-butylpropanediol di(meth)acrylate, bisphenol A di(meth)acrylate, bisphenol A ethylene oxide adduct di(meth)acrylate, bisphenol A propylene oxide adduct di(meth)acrylate, bisphenol A diglycidyl ether di(meth)acrylate, and Examples include esters of (meth)acrylic acid with polyhydric alcohols such as opentyl glycol di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, cyclic trimethylolpropane formal(meth)acrylate, dioxane glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and EO-modified diglycerin tetra(meth)acrylate, as well as 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene. Specific examples include Light Acrylate 9EG-A (manufactured by Kyoeisha Chemical Co., Ltd.), Aronics M-220 (manufactured by Toagosei Co., Ltd.), Light Acrylate 1,9ND-A (manufactured by Kyoeisha Chemical Co., Ltd.), Light Acrylate DGE-4A (manufactured by Kyoeisha Chemical Co., Ltd.), Light Acrylate DCP-A (manufactured by Kyoeisha Chemical Co., Ltd.), SR-531 (manufactured by Sartomer), CD-536 (manufactured by Sartomer), and others.

[0068] In the present invention, the radical polymerizable curable composition may contain, in addition to the radical polymerizable compound, an acrylic oligomer obtained by polymerizing (meth)acrylic monomer and having no polymerizable groups. By including the acrylic oligomer in the radical polymerizable curable composition, curing shrinkage when the composition is irradiated and cured with active energy rays can be reduced, and interfacial stress between the functional layer and the polarizer and other optical films can be reduced. As a result, a decrease in adhesion between the functional layer and the polarizer and other optical films can be suppressed.

[0069] Radical polymerizable curable compositions are preferably low viscosity when considering workability and uniformity during coating. Therefore, acrylic oligomers obtained by polymerizing (meth)acrylic monomers and that do not have polymerizable groups are also preferably low viscosity. As acrylic oligomers that are low viscosity and can prevent curing shrinkage of the functional layer, those with a weight-average molecular weight (Mw) of 15,000 or less are preferred, those with a weight-average molecular weight (Mw) of 10,000 or less are preferred, and those with a weight-average molecular weight (Mw) of 5,000 or less are particularly preferred. On the other hand, in order to sufficiently suppress curing shrinkage of the functional layer, the weight-average molecular weight (Mw) of the acrylic oligomer is preferably 500 or more, more preferably 1,000 or more, and particularly preferred to be 1,500 or more. Examples of (meth)acrylic monomers that constitute acrylic oligomers include, specifically, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, 2-methyl-2-nitropropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, S-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, t-pentyl (meth)acrylate, 3-pentyl (meth)acrylate, 2,2-dimethylbutyl (meth)acrylate, n-hexyl (meth)acrylate, cetyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, N-octadecyl (meth)acrylate, and other alkyl (meth)acrylic acid (C1-20) esters, as well as, for example, cycloalkyl (meth)acrylates (e.g., cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, etc.), aralkyl (meth)acrylates (e.g., benzyl (meth)acrylate, etc.), polycyclic (meth)acrylates (e.g., 2-isobornyl (meth)acrylate, 2-norbornylmethyl (meth)acrylate, 5-norbornen-2-yl-methyl (meth)acrylate, 3-methyl-2-norbornylmethyl ( (meth)acrylates, etc.), hydroxyl group-containing (meth)acrylic acid esters (e.g., hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropylmethyl-butyl (meth)methacrylate, etc.), alkoxy group-containing (meth)acrylic acid esters (2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethyl carbitol (meth)acrylate, phenoxyethyl (meth)acrylate, etc.), epoxy group-containing (meth)acrylic acid esters (e.g., glycidyl (meth)acrylate, etc.), halogen-containing (meth)acrylic acid esters (e.g., 2,2,2-trifluoroethyl (meth)acrylate, 2,2Examples include 2-trifluoroethylethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, etc.), and alkylaminoalkyl (meth)acrylates (e.g., dimethylaminoethyl (meth)acrylate). These (meth)acrylates can be used alone or in combination of two or more types. Specific examples of acrylic oligomers (E) include "ARUFON" from Toagosei Co., Ltd., "Actflow" from Soken Chemical Co., Ltd., and "JONCRYL" from BASF Japan.

[0070] In the present invention, the radical polymerizable curable composition may contain cationic polymerizable compounds in addition to radical polymerizable compounds. Cationic polymerizable compounds are classified into monofunctional cationic polymerizable compounds having one cationic polymerizable functional group in the molecule, and polyfunctional cationic polymerizable compounds having two or more cationic polymerizable functional groups in the molecule. Monofunctional cationic polymerizable compounds have relatively low liquid viscosity, so including them in a composition can reduce the liquid viscosity of the composition. Furthermore, monofunctional cationic polymerizable compounds often have functional groups that exhibit various functions, and including them in a radical polymerizable curable composition can allow the cured product to exhibit various functions. Polyfunctional cationic polymerizable compounds can cause three-dimensional crosslinking of the cured product of the radical polymerizable curable composition.

[0071] Cationic polymerizable functional groups include epoxy groups, oxetanyl groups, and vinyl ether groups. Compounds containing epoxy groups include aliphatic epoxy compounds, alicyclic epoxy compounds, and aromatic epoxy compounds. Examples of alicyclic epoxy compounds include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, caprolactone-modified, trimethylcaprolactone-modified, and valerolactone-modified 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and specifically, Celoxide 2021, Celoxide 2021A, Celoxide 2021P, Celoxide 2081, Celoxide 2083, Celoxide 2085 (all manufactured by Daicel Chemical Industries, Ltd.), and Cyracure UVR-6105, Cyracure UVR-6107, Cyracure 30, R-6110 (all manufactured by Dow Chemical Japan Ltd.). Compounds containing an oxetanyl group have the effect of improving the curability of radical polymerizable curable compositions and reducing the liquid viscosity of the composition, therefore, they are included. It is preferable to include them. Examples of compounds having an oxetanyl group include 3-ethyl-3-hydroxymethyloxetane, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]benzene, 3-ethyl-3-(phenoxymethyl)oxetane, di[(3-ethyl-3-oxetanyl)methyl]ether, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, and phenol novolac oxetane. Aronoxetane OXT-101, Aronoxetane OXT-121, Aronoxetane OXT-211, Aronoxetane OXT-221, Aronoxetane OXT-212 (all manufactured by Toagosei Co., Ltd.) are commercially available. Compounds having a vinyl ether group are preferable to include because they have the effect of improving the curability of the cationic polymerizable adhesive composition and reducing the liquid viscosity of the composition.Compounds having a vinyl ether group include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, triethylene glycol divinyl ether, cyclohexanedimethanol divinyl ether, cyclohexanedimethanol monovinyl ether, tricyclodecane vinyl ether, cyclohexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, and pentaerythritol-type tetravinyl ether.

[0072] In this invention, a laminated optical film is manufactured using a first optical film with a functional layer. Furthermore, by incorporating this laminated optical film, an image display device and even an organic EL display device can be created.

[0073] In the method for manufacturing a laminated optical film according to the present invention, when the optical film is an iodine-based polarizer, and further when the optical film is an iodine-based polarizer and the second optical film is a phase difference film, when the laminated optical film is incorporated into an image display device, the barrier function layer exhibits a barrier function that significantly inhibits the movement of iodine. As a result, iodine does not reach the panel or sensor of the image display device and remains inside the polarizer. Consequently, even when an image display device incorporating an iodine-based polarizer with a barrier function layer is used under high temperature and high humidity conditions, corrosion of the panel or sensor of the image display device by iodine can be sufficiently prevented.

[0074] Figure 1 shows an example of an embodiment, illustrating an image display device incorporating a laminated optical film equipped with an iodine-based polarizer with a barrier function layer, manufactured by the method for manufacturing a laminated optical film according to the present invention. In the embodiment shown in Figure 1, the image display device A is an organic EL image display device equipped with an organic light-emitting diode panel 8, and includes an iodine-based polarizer 1 (iodine-based polarizer 1+2 with barrier function layer) equipped with a barrier layer 2. An adhesive layer 3 is provided on the barrier layer 2 side of the iodine-based polarizer 1 equipped with the barrier layer 2, and the laminated optical film 10 is formed by laminating the iodine-based polarizer 1+2 with barrier function layer and a phase difference film 4 via the adhesive layer 3. In this invention, the laminated optical film may be composed of three or more optical films, as long as it comprises at least an iodine-based polarizer 1 → barrier layer 2 → adhesive layer 3 → phase difference film 4 from the outer surface (visible surface) toward the inner surface. In the embodiment shown in Figure 1, the image display device A comprises, in order from the outermost surface toward the organic light-emitting diode panel 8, a transparent protective film 7 → second adhesive layer 6 → iodine-based polarizer 1 → barrier layer 2 → adhesive layer 3 → phase difference film 4 → adhesive layer 5 → organic light-emitting diode panel 8. As described above, even when the laminated optical film 10 manufactured in this embodiment is exposed to high temperature and high humidity, the iodine contained in the iodine-based polarizer 1+2 remains within the barrier layer 2 due to the barrier function of the barrier layer 2, thereby preventing iodine from penetrating the phase difference film 4 and adhesive layer 5, and furthermore, the organic light-emitting diode panel 8 or touch sensor (not shown), and thus sufficiently preventing corrosion of the panel or sensor of the image display device.

[0075] <Adhesive Layer> The adhesive layer may be formed by a cured layer of a radical polymerizable curable composition used to constitute the functional layer described above. However, the curable components such as radical polymerizable compounds and photopolymerization initiators may be appropriately changed depending on the type of first optical film and second optical film. From the viewpoint of thinning, the thickness of the adhesive layer is preferably 0.1 to 5 μm.

[0076] <Second Adhesive Layer> The second adhesive layer may also be formed by a cured layer of a radical polymerizable curable composition for constituting the functional layer described above. However, the curable components such as radical polymerizable compounds and photopolymerization initiators may be appropriately changed depending on the type of first optical film and second optical film. Alternatively, it may be formed by a radical polymerizable adhesive composition, a cationic polymerizable adhesive composition, or an aqueous adhesive composition known to those skilled in the art. As the aqueous adhesive composition, an aqueous solution of an aqueous adhesive such as an isocyanate adhesive, a polyvinyl alcohol adhesive, a gelatin adhesive, a vinyl latex adhesive, or an aqueous polyester adhesive (for example, with a solid content concentration of 0.5 to 60% by weight) is preferably used. From the viewpoint of thinning, the thickness of the second adhesive layer is preferably 0.1 to 5 μm.

[0077] The laminated optical film produced by the method for manufacturing a laminated optical film according to the present invention is bonded to an organic light-emitting diode panel or a touch sensor by providing an adhesive layer on the second optical film side (the phase difference film side in the embodiment shown in Figure 1).

[0078] <Adhesive Layer> The adhesive forming the adhesive layer is not particularly limited, but for example, an adhesive based on polymers such as acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyethers, fluorine-based or rubber-based polymers can be appropriately selected and used. In particular, adhesives that have excellent optical transparency, exhibit appropriate wettability, cohesiveness and adhesion properties, and have excellent weather resistance and heat resistance, such as acrylic adhesives, are preferably used.

[0079] For the exposed surface of the adhesive layer, a separator is temporarily attached and covered to prevent contamination until it is put into practical use. This prevents contact with the adhesive layer under normal handling conditions. As for the separator, except for the thickness conditions mentioned above, suitable thin materials such as plastic film, rubber sheet, paper, cloth, nonwoven fabric, net, foam sheet, metal foil, or laminates thereof can be used, and may be coated with a suitable release agent such as silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide as needed, in accordance with conventional methods.

[0080] In the present invention, the processes other than the coating process and the irradiation process in the method for manufacturing a laminated optical film are described below.

[0081] (Lamination process) The functional layer surface of the first optical film with the functional layer and the coated surface of the adhesive composition of the second optical film are laminated together. When laminating the first optical film with the functional layer and the second optical film via the adhesive composition, a roll laminator or the like is used for lamination.

[0082] (Bonding process) The first optical film with the functional layer (e.g., iodine-based polarizer) and the second optical film (e.g., phase difference film) are bonded together via an adhesive layer formed by curing at least the adhesive composition by irradiating with active energy rays from the side of the first optical film with the functional layer (e.g., iodine-based polarizer) or from the side of the second optical film (e.g., phase difference film). The irradiation direction of the active energy rays (electron beam, ultraviolet light, visible light, etc.) can be any suitable direction.

[0083] When irradiating with an electron beam, any suitable irradiation conditions can be adopted, as long as they are conditions that can at least cure the adhesive composition. For example, the acceleration voltage for electron beam irradiation is preferably 5 kV to 300 kV, and more preferably 10 kV to 250 kV. If the acceleration voltage is less than 5 kV, the electron beam may not reach the adhesive, resulting in insufficient curing. If the acceleration voltage exceeds 300 kV, the penetrating force through the sample may be too strong, potentially damaging the functional layer-attached first optical film (e.g., iodine-based polarizer) and the second optical film (e.g., phase difference film). The irradiation dose is 5 to 100 kGy, more preferably 10 to 75 kGy. If the irradiation dose is less than 5 kGy, the adhesive will not cure sufficiently. If it exceeds 100 kGy, the functional layer-attached first optical film (e.g., iodine-based polarizer) and the second optical film (e.g., phase difference film) will be damaged, resulting in a decrease in mechanical strength and yellowing, making it impossible to obtain the desired optical properties.

[0084] Electron beam irradiation is usually performed in an inert gas environment, but if necessary, it may be performed in air or under conditions with a small amount of oxygen introduced. Depending on the materials of the functional layered first optical film (e.g., iodine-based polarizer) and the second optical film (e.g., phase difference film), by appropriately introducing oxygen, oxygen inhibition can be intentionally caused on the surfaces of the functional layered first optical film (e.g., iodine-based polarizer) and the second optical film (e.g., phase difference film) that are first struck by the electron beam, thereby preventing damage to the functional layered first optical film (e.g., iodine-based polarizer) and the second optical film (e.g., phase difference film), and allowing the electron beam to be efficiently directed only at the adhesive.

[0085] In the method for manufacturing a laminated optical film according to the present invention, it is preferable to use an active energy ray that includes visible light in the wavelength range of 380 nm to 450 nm, and more particularly, an active energy ray that has the highest irradiation amount of visible light in the wavelength range of 380 nm to 450 nm. In the method for manufacturing a laminated optical film according to the present invention, as the active energy ray, a gallium-filled metal halide lamp or an LED light source that emits light in the wavelength range of 380 to 440 nm is preferred. Alternatively, a light source containing ultraviolet and visible light such as a low-pressure mercury lamp, medium-pressure mercury lamp, high-pressure mercury lamp, ultra-high-pressure mercury lamp, incandescent bulb, xenon lamp, halogen lamp, carbon arc lamp, metal halide lamp, fluorescent lamp, tungsten lamp, gallium lamp, excimer laser, or sunlight can be used, and ultraviolet light with wavelengths shorter than 380 nm can also be blocked using a bandpass filter. To improve the adhesion performance of the adhesive layer between the optical film and the second optical film while preventing curling of the laminated optical film, it is preferable to use a gallium-filled metal halide lamp and active energy rays obtained through a bandpass filter capable of blocking light with wavelengths shorter than 380 nm, or to use active energy rays with a wavelength of 405 nm obtained using an LED light source.

[0086] When manufacturing the laminated optical film according to the present invention on a continuous line, the line speed depends on the curing time of the adhesive composition, but is preferably 1 to 500 m / min, more preferably 5 to 300 m / min, and even more preferably 10 to 100 m / min. If the line speed is too low, productivity will be poor, or the damage to the optical film and the second optical film will be too great, making it impossible to produce a laminated optical film that can withstand durability tests. If the line speed is too high, the curing of the adhesive composition will be insufficient, and the desired adhesion may not be obtained.

[0087] (Laminated Optical Film) The laminated optical film produced by the method for manufacturing a laminated optical film according to the present invention can be preferably used for forming various image display devices such as organic EL displays and liquid crystal displays. The formation of organic EL displays and liquid crystal displays can be carried out in accordance with conventional methods. That is, liquid crystal displays are generally formed by assembling components such as liquid crystal cells, polarizing films or optical films, and lighting systems as needed, and incorporating a drive circuit. However, the present invention is not particularly limited except for the use of the laminated optical film according to the present invention, and can be carried out in accordance with conventional methods. Any type of liquid crystal cell can be used, for example, TN type, STN type, or π type.

[0088] Appropriate liquid crystal display devices can be formed, such as liquid crystal display devices in which optical laminates are arranged on one or both sides of a liquid crystal cell, or in which a backlight or reflector is used in the illumination system. In this case, the optical laminate according to the present invention can be installed on one or both sides of the liquid crystal cell. When optical laminates are provided on both sides, they may be the same or different. Furthermore, when forming a liquid crystal display device, appropriate components such as diffusers, anti-glare layers, anti-reflective films, protective plates, prism arrays, lens array sheets, light diffusers, and backlights can be arranged in appropriate positions in one or more layers.

[0089] The following describes some embodiments of the present invention, but the embodiments of the present invention are not limited to these.

[0090] <Iodine-based polarizer> A laminate in which a 9 μm thick PVA layer was formed on an amorphous PET substrate was stretched by air-assisted stretching at a stretching temperature of 130°C to produce a stretched laminate. Next, a colored laminate was produced by dyeing the stretched laminate, and then an optical film laminate containing a 5 μm thick PVA layer was produced by stretching the colored laminate in boric acid water at a stretching temperature of 65°C, so that the total stretching ratio was 5.94 times, integrally with the amorphous PET substrate. Through this two-stage stretching, an optical film laminate containing a 5 μm thick PVA layer (iodine-based polarizer) was obtained, in which the PVA molecules of the PVA layer formed on the amorphous PET substrate were highly oriented, and the iodine adsorbed by dyeing was highly oriented in one direction as a polyiodide ion complex, constituting a thin polarizer.

[0091] <Photopolymerizable Liquid Crystal Composition> A photopolymerizable liquid crystal compound exhibiting a nematic liquid crystal phase (BASF's "Paliocolor LC242") was dissolved in cyclopentanone to prepare a solution with a solid content of 30% by weight. A surfactant (BYK-360, Bic Chemie) and a photopolymerization initiator (Omnirad 907, IGM Resins) were added to this solution to prepare a liquid crystal composition solution. The amounts of surfactant and photopolymerization initiator added were 0.01 parts by weight and 3 parts by weight, respectively, per 100 parts by weight of the photopolymerizable liquid crystal compound.

[0092] <Phase Difference Film> Using a biaxially oriented norbornene-based film (Zeonor Film, manufactured by Nippon Zeon, thickness: 33 μm, frontal retardation: 135 nm) as a substrate, the above liquid crystal composition was applied to the substrate by a bar coater so that the phase difference was λ / 2, and the film was heated at 100°C for 3 minutes to orient the liquid crystals. After cooling to room temperature, the film was subjected to a nitrogen atmosphere with an integrated light intensity of 400 mJ / cm². ２ A laminate was obtained in which a homogeneous oriented liquid crystal layer (a liquid crystal phase difference film) was provided by photocuring by irradiation with ultraviolet light.

[0093] <Laminated Optical Film> The PVA layer surface of an optical film laminate containing a PVA layer (iodine-based polarizer) is treated with a corona treatment machine at a treatment density of 50 W・min / m ２Corona treatment was performed on the corona-treated surface. The radical polymerizable curable compositions used in Examples 1 to 9 and Comparative Example 1 were coated to a coating thickness of 4 μm using an MCD coater (manufactured by Fuji Machinery Co., Ltd.) (cell shape: honeycomb, gravure roll line count: 250 lines / inch, opening ratio of cells formed on the gravure roll: 40%, rotation speed 120% / line speed) (first coating step). The coating thickness was measured using a spectroscopic interferometry film thickness meter (manufactured by Ocean Optics: spectrometer "USB2000+", light source "HL-2000", fiber "OCF-103995").

[0094] In the irradiation step, the radical polymerizable curable composition used in Examples 1 to 9 was cured by irradiating the surface of the PVA layer (iodine-based polarizer) of an optical film laminate coated with a radical polymerizable curable composition with light having a maximum emission wavelength of 365 nm (or 405 nm) using a UV-LED device (manufactured by Iwasaki Electric Co., Ltd., product name "e-CURE") to produce an iodine-based polarizer with a barrier functional layer (thickness 4 μm) (irradiation step). After the irradiation step, the amorphous PET substrate was peeled off from the PVA layer (iodine-based polarizer). In Comparative Example 1, the irradiation step was not performed, and an iodine-based polarizer coated with an uncured radical polymerizable curable composition was used. In Examples 8 and 9, the film was heated before curing, and then light irradiation was performed.

[0095] The materials constituting the radical polymerizable curable compositions used in Examples 1 to 9 and Comparative Example 1 are as follows: ((Meth)acrylate (A)) Tricyclodecane dimethanol diacrylate: trade name "Light Acrylate DCP-A", manufactured by Kyoeisha Chemical Co., Ltd., compound described in (A-1) Isobornyl acrylate: trade name "IB-XA", manufactured by Osaka Organic Chemical Industry Co., Ltd., compound described in (A-2) ((Meth)acrylate (B)) 4-Hydroxybutyl acrylate: trade name "4-HBA", manufactured by Osaka Organic Chemical Industry Co., Ltd. (Initiator) Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide: trade name "Omnirad 819", manufactured by IGM Resins B. V. 1-Hydroxycyclohexyl-phenyl ketone: trade name "Omnirad 184", manufactured by IGM Resins B. V. 2,4-Diethylthioxanthone, manufactured by Nippon Kayaku Co., Ltd.: Product name "DETX-S", manufactured by Nippon Kayaku Co., Ltd.

[0096] For the homogeneous oriented liquid crystal layer (liquid crystal phase difference film) surface of a λ / 2 phase difference film, a corona treatment machine was used to perform a treatment at a density of 50 W・min / m². ２ Corona treatment was performed on the corona-treated surface. The adhesive compositions used in Examples 1 to 9 and Comparative Example 1 (in Tables 1 and 2, adhesive composition (1) is simply referred to as "adhesive (1)") were applied to a coating thickness of 1.1 μm using an MCD coater (manufactured by Fuji Machinery Co., Ltd.) (cell shape: honeycomb, gravure roll line count: 700 lines / inch, opening ratio of cells formed on the gravure roll: 40%, rotation speed 140% / line speed) (second coating step). Next, the λ / 2 phase difference films were bonded together using a roll machine so that the slow layer axis of the λ / 2 phase difference film was at a 15° angle to the transmission axis of the polarizer (bonding step). The bonding line speed was 15 m / min. After that, a visible light irradiation device (Heraeus Light HAMMER 10 Mark III, bulb: V bulb, peak illuminance: 1600 mW / cm²) was used from the phase difference film side. ２ Total irradiation dose: 1000 / mJ / cm² ２The illuminance and cumulative irradiation dose of the active energy rays were measured using a Power Puck 2 (manufactured by EIT, UVV measurement). The adhesive compositions used in Examples 1 to 9 and Comparative Example 1 were cured by irradiating them with active energy rays, thereby producing a laminated optical film in which the PVA layer (iodine-based polarizer) of the optical film laminate and the phase difference film were laminated via the adhesive layer. The thickness of the adhesive layer was 1 μm. After the bonding process, the substrate (biaxially oriented norbornene-based film) was peeled off from the phase difference film.

[0097] The materials constituting the adhesive composition (1) used in Examples 1 to 9 and Comparative Example 1 are as follows. The formulation table of adhesive (1) is shown in Table 1. ((Meth)acrylate) ・2-hydroxyethylacrylamide: trade name "HEAA", manufactured by KJ Chemicals ・Phenoxydiethylene glycol acrylate: trade name "Light Acrylate P2H-A", manufactured by Kyoeisha Chemicals ・1,9-nonanediol diacrylate: trade name "Light Acrylate 1,9ND-A", manufactured by Kyoeisha Chemicals (Acrylic oligomer) ・Acrylic oligomer: trade name "ARFUON UP-1190", manufactured by Toagosei Co., Ltd. (Initiator) ・2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone-1-one: trade name "Omnirad 907", manufactured by IGM Resins B. V. 2,4-Diethylthioxanthone, manufactured by Nippon Kayaku Co., Ltd.: Product name "DETX-S", manufactured by Nippon Kayaku Co., Ltd.

[0098]

[0099] The adhesion, iodine barrier properties in the adhesive layer, and optical durability of the laminated optical films produced in Examples 1 to 9 and Comparative Example 1 were evaluated by the methods described below.

[0100] (Adhesion of Laminated Optical Film) The amorphous PET substrate of the laminated optical film manufactured above was peeled off, and double-sided tape (No. 500, manufactured by Nitto Denko Corporation) was attached to the peeled surface (iodine-based polarizer surface). Furthermore, adhesive tape (No. 360, manufactured by Nitto Denko Corporation) was attached to the phase difference layer side for reinforcement, and then the film was cut to a size of 200 mm in the direction perpendicular to the stretching direction of the iodine-based polarizer and 15 mm in the direction parallel to it. After making an incision between the iodine-based polarizer and the phase difference layer with a utility knife, the release film of the double-sided tape was peeled off, and the adhesive side was attached to a glass plate. Next, the thin polarizer and transparent protective film were peeled off at a peeling speed of 20,000 mm / min in the 90-degree direction using an angle-adjustable adhesive / film peeling analyzer (VPA-2, manufactured by Kyowa Interface Chemical Co., Ltd.), and the peeling strength (N / 15 mm) was measured.

[0101] (Iodine barrier properties in the adhesive layer of a laminated optical film) In order to laminate an adhesive layer on the phase difference layer side of the laminated optical film manufactured above, the adhesive layer was manufactured by the following method.

[0102] <Adhesive Layer> A monomer mixture containing 99 parts by weight of butyl acrylate (BA) and 1 part by weight of 4-hydroxybutyl acrylate (HBA) was charged into a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser. Furthermore, 0.1 parts by weight of 2,2'-azobisisobutyronitrile was added to 100 parts by weight of the monomer mixture (solids) as a polymerization initiator along with ethyl acetate. After introducing nitrogen gas and purging with nitrogen while gently stirring, the polymerization reaction was carried out for 7 hours while maintaining the liquid temperature in the flask at around 55°C. Subsequently, ethyl acetate was added to the resulting reaction solution to prepare a solution of (meth)acrylic polymer A1 with a weight-average molecular weight of 1.6 million, with a solids content concentration of 30%. An acrylic adhesive composition was prepared by blending 0.1 parts by weight of an isocyanate crosslinking agent (trade name: Takenate D110N, trimethylolpropane xylylene diisocyanate, manufactured by Mitsui Chemicals, Inc.), 0.3 parts by weight of a peroxide crosslinking agent, benzoyl peroxide (trade name: Niper BMT, manufactured by Nippon Oil & Fats Co., Ltd.), and 0.08 parts by weight of a silane coupling agent (trade name: KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) with 100 parts by weight of the solid content of the obtained (meth)acrylic polymer A1 solution. The acrylic adhesive composition was uniformly coated onto the surface of a 38 μm thick polyethylene terephthalate film (release liner) treated with a silicone release agent using a fountain coater, and dried in a 155°C air-circulating constant temperature oven for 2 minutes to form a 20 μm thick adhesive layer on the surface of the release liner.

[0103] The adhesive-coated release liner prepared above was transferred to the phase difference layer side of the laminated optical film, and then the release liner was peeled off. Next, an evaluation sample was prepared by bonding the adhesive layer side of the laminated optical film to an alkali-free glass with a thickness of 0.7 mm and an aluminum vapor-deposited film attached. Using this evaluation sample, a corrosion test was conducted by exposing it to an environment of 60°C and 95% humidity for 240 hours. The presence or absence of corrosion was confirmed visually, and if light leakage occurred in the aluminum vapor-deposited film due to iodine penetrating from the iodine-based polarizer of the laminated optical film, corrosion was determined to be present.

[0104] (Optical durability of laminated optical film) A polarizing film (sample for humidification durability test evaluation) was prepared by laminating one side of an alkali-free glass 0.7 mm thick via an adhesive layer (thickness 20 μm). Using this sample, a humidification reliability test of the polarization characteristics was conducted in an environment of 60°C and 95% humidity. Details of the humidification reliability test are shown below. The obtained polarizing film was exposed to an environment of 60°C and 95% humidity for 240 hours, and the degree of polarization before and after exposure was measured using a spectrophotometer with an integrating sphere (V7100 manufactured by JASCO Corporation), and the change in the degree of polarization ΔPz (%) = |(degree of polarization before exposure (%)) - (degree of polarization after exposure (%))| was calculated.

[0105]

[0106] The results in Table 2 show that the laminated optical films according to Examples 1 to 9 exhibit excellent adhesion between the iodine-based polarizer and the phase difference film, and the barrier function of the adhesive layer against iodine is fully exercised, thus effectively preventing corrosion of the panel or sensor of the image display device even when used under high temperature and high humidity conditions. On the other hand, the laminated optical film according to Comparative Example 1 exhibits excellent adhesion between the iodine-based polarizer and the phase difference layer, but its barrier function against iodine is inferior, and therefore it cannot prevent corrosion of the panel or sensor of the image display device when used under high temperature and high humidity conditions. Furthermore, the laminated optical film according to Comparative Example 1 also exhibits inferior optical durability.

[0107] A. Image display device, 1. Iodine-based polarizer, 2. Barrier layer, 3. Adhesive layer, 4. Phase difference film, 5. Adhesive layer, 6. Second adhesive layer, 7. Transparent protective film, 8. Organic light-emitting diode panel, 10. Laminated optical film

Claims

1. A method for manufacturing a laminated optical film in which at least a first optical film and a second optical film are laminated via an adhesive layer, wherein the adhesive layer is a cured layer of an adhesive composition, the method comprising: a first coating step of coating the first optical film with a radical polymerizable curable composition; a second coating step of coating the second optical film with the adhesive composition; an irradiation step of irradiating the coated surface of the first optical film with the radical polymerizable curable composition with active energy rays to cure at least a portion of the radical polymerizable curable composition, thereby manufacturing a first optical film with a functional layer laminated on the first optical film; a bonding step of bonding the functional layer surface of the first optical film with the functional layer and the coated surface of the adhesive composition of the second optical film; and an adhesion step of bonding the first optical film with the functional layer and the second optical film via an adhesive layer formed by irradiating from the side of the first optical film with the functional layer or the side of the second optical film with active energy rays to cure at least the adhesive composition.

2. The method for manufacturing a laminated optical film according to claim 1, wherein the irradiation step is a step of irradiating the coated surface of the first optical film with the radical polymerizable curable composition using a UV-LED as the active energy ray, the light source having a maximum emission wavelength in the wavelength range of 280 to 420 nm.

3. The irradiation conditions for the UV-LED are 500 to 3000 mW / cm². ２ Illuminance range of 250-3000 mJ / cm ２ A method for manufacturing a laminated optical film according to claim 1 or 2, wherein the light intensity range is within the specified range.

4. A method for manufacturing a laminated optical film according to any one of claims 1 to 3, wherein in a first coating step of coating the first optical film with a radical polymerizable curable composition, the coating thickness when coating the first optical film with the radical polymerizable curable composition is less than 5 μm.

5. A method for manufacturing a laminated optical film according to any one of claims 1 to 4, wherein in a second coating step of coating the second optical film with the adhesive composition, the coating thickness when coating the second optical film with the adhesive composition is less than 5 μm.

6. The method for producing a laminated optical film according to any one of claims 1 to 5, wherein in the irradiation step, the uncured portion of the radical polymerizable curable composition is 20% by mass or less.

7. A method for manufacturing a laminated optical film according to any one of claims 1 to 6, wherein the first optical film is an iodine-based polarizer.

8. The method for manufacturing a laminated optical film according to claim 7, wherein the thickness of the iodine-based polarizer is 8 μm or less.

9. The method for manufacturing a laminated optical film according to any one of claims 1 to 8, wherein the second optical film is a liquid crystal phase difference film.

10. The method for manufacturing a laminated optical film according to claim 9, wherein the thickness of the phase difference film is 5 μm or less.

Images