Optical film with adhesive layer and image display device having the same

Abstract

To provide an optical film with an adhesive layer, which significantly suppresses the problems of missing glue in a deformed portion thereof and separation in a high-temperature high-humidity environment.SOLUTION: An optical film with an adhesive layer according to the present invention comprises an optical film and an adhesive layer provided on one surface of the optical film. The optical film with the adhesive layer has a non-rectangular deformed portion, and the adhesive layer exhibits a creep value of 500 μm or less at 85°C.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive layer-attached optical film and an image display device including the pressure-sensitive adhesive layer-attached optical film. [Background technology]

[0002] Optical films are widely used in image display devices such as mobile phones and notebook personal computers to realize image display and / or improve the performance of the image display. Optical films are typically provided with a pressure-sensitive adhesive layer to form pressure-sensitive adhesive-layered optical films that can be attached to image display cells. In recent years, there have been cases where optical films are desired to be processed into shapes other than rectangular (deformed shapes: for example, the formation of notches and / or through holes). However, there is a problem in that the deformed portions of pressure-sensitive adhesive-layered optical films are prone to adhesive chipping (a phenomenon in which the edge of the pressure-sensitive adhesive layer is chipped). Furthermore, pressure-sensitive adhesive layers have the problem of peeling under high-temperature and high-humidity environments. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-090896 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made to solve the above-mentioned conventional problems, and its main object is to provide an optical film with a pressure-sensitive adhesive layer in which glue chipping in irregularly processed areas is significantly suppressed and peeling in high-temperature, high-humidity environments is significantly suppressed. [Means for solving the problem]

[0005] The pressure-sensitive adhesive layer-attached optical film of the present invention comprises an optical film and a pressure-sensitive adhesive layer on one side of the optical film, the pressure-sensitive adhesive layer having an irregular shape other than rectangular, and the pressure-sensitive adhesive layer having a creep value of 500 μm or less at 85° C. In one embodiment, the creep value is 5 μm or more. In one embodiment, the pressure-sensitive adhesive layer has a thickness of 2 μm to 20 μm. In one embodiment, a separator is temporarily and releasably attached to the surface of the pressure-sensitive adhesive layer opposite the optical film, and the peel strength of the separator is 0.04 N / 50 mm to 0.5 N / 50 mm. In one embodiment, the optical film includes a polarizer. In one embodiment, the optical film further includes a retardation layer. According to another aspect of the present invention, there is provided an image display device, which includes the pressure-sensitive adhesive layer-attached optical film. [Effects of the Invention]

[0006] According to an embodiment of the present invention, in an optical film with an adhesive layer having an irregular shape (irregularly shaped portion) other than rectangular, by setting the creep value of the adhesive layer at 85°C within a predetermined range, it is possible to realize an optical film with an adhesive layer in which glue chipping in the irregularly shaped portion is significantly suppressed and peeling in a high-temperature, high-humidity environment is significantly suppressed. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a schematic plan view illustrating an example of an irregular shape or irregularly processed portion in the pressure-sensitive adhesive layer-attached optical film according to an embodiment of the present invention. [Figure 2] 10A and 10B are schematic plan views illustrating modified examples of irregular shapes or irregularly processed portions in a pressure-sensitive adhesive layer-attached optical film according to an embodiment of the present invention. [Figure 3] FIG. 10 is a schematic plan view illustrating another modified example of the irregular shape or irregularly processed portion in the pressure-sensitive adhesive layer-attached optical film according to the embodiment of the present invention. [Figure 4]FIG. 10 is a schematic plan view illustrating another modified example of the irregular shape or irregularly processed portion in the pressure-sensitive adhesive layer-attached optical film according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] Specific embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. Note that the drawings are schematic for clarity, and the ratios of length, width, thickness, etc., as well as angles, etc., in the drawings are different from the actual ones.

[0009] A. Overview of optical film with adhesive layer A pressure-sensitive adhesive layer-attached optical film according to an embodiment of the present invention comprises an optical film and a pressure-sensitive adhesive layer on one side of the optical film. In an embodiment of the present invention, the pressure-sensitive adhesive layer-attached optical film has an irregular shape other than rectangular. In this specification, "having an irregular shape other than rectangular" refers to the pressure-sensitive adhesive layer-attached optical film having a shape other than rectangular (including rectangular shapes with chamfered corners) in plan view. The irregular shape is typically a deformed portion that has been deformed. Therefore, a "pressure-sensitive adhesive layer-attached optical film having an irregular shape other than rectangular" (hereinafter sometimes referred to as a "deformed optical film") includes not only an irregular optical film whose entire shape (i.e., the outer edge defining the film's shape in plan view) is other than rectangular, but also a rectangular optical film having an irregularly shaped portion formed in a portion spaced inward from the outer edge. While such irregularly shaped portions are prone to adhesive chipping, an embodiment of the present invention can significantly reduce such adhesive chipping. Examples of irregular shapes (irregularly shaped portions) include through holes and machined portions that become recesses in plan view, as shown in FIGS. 1 and 2. Representative examples of recesses include a boat-like shape, a V-shaped notch, and a U-shaped notch. Another example of an irregular shape (irregularly shaped portion) is a shape corresponding to an automobile meter panel, as shown in Figures 3 and 4. This shape includes a portion in which the outer edge is formed in an arc shape that follows the rotation direction of the meter needle and the outer edge forms a V-shape (including a rounded shape) that is convex inward in the planar direction. Needless to say, the shape of the irregular shape (irregularly shaped portion) is not limited to the illustrated example. For example, the shape of the through hole may be any appropriate shape (e.g., ellipse, triangle, rectangle, pentagon, hexagon, octagon) depending on the purpose, other than the approximately circular shape shown in the example. Furthermore, the through hole may be provided in any appropriate position depending on the purpose. The through-hole may be provided in the approximate center of the longitudinal end of the rectangular optical film as shown in Fig. 2, or at a predetermined position on the longitudinal end, or at a corner of the optical film; although not shown, it may also be provided in the lateral end of the rectangular optical film; or it may be provided in the center of the irregular optical film as shown in Fig. 3 or 4. Furthermore, the shapes of the illustrated examples may be appropriately combined depending on the purpose.For example, through holes may be formed at any position in the profiled optical film of Fig. 1, or V-shaped notches and / or U-shaped notches may be formed at any appropriate position on the outer edge of the profiled optical film of Fig. 3 or 4. Such profiled optical films may be suitably used in image display devices such as automobile instrument panels, smartphones, tablet PCs, and smartwatches.

[0010] In an embodiment of the present invention, the creep value of the pressure-sensitive adhesive layer at 85°C is 500 μm or less, preferably 5 μm to 500 μm. If the creep value of the pressure-sensitive adhesive layer is within this range, it is possible to realize an optical film with a pressure-sensitive adhesive layer in which glue chipping in contoured areas is significantly suppressed and peeling under high-temperature and high-humidity environments is significantly suppressed. The configuration of the pressure-sensitive adhesive layer will be specifically described in Section C below.

[0011] The amount of glue chipping in the adhesive layer (particularly the adhesive layer in the profiled portion) in the adhesive layer-attached optical film is preferably 80 μm or less, more preferably 65 μm or less, and even more preferably 50 μm or less. The smaller the amount of glue chipping, the better, and the lower limit may be, for example, 5 μm. In this specification, the "amount of glue chipping" refers to the maximum amount of the adhesive layer chipped inward in the planar direction from the outer edge of the optical film (including the outer edge of the through holes).

[0012] In one embodiment, a separator is temporarily and releasably attached to the surface of the pressure-sensitive adhesive layer opposite the optical film. Examples of the separator include plastic (e.g., polyethylene terephthalate (PET), polyethylene, polypropylene) films, nonwoven fabrics, and paper, whose surfaces are coated with a release agent such as a silicone-based release agent, a fluorine-based release agent, or a long-chain alkyl acrylate-based release agent. The thickness of the separator can be any appropriate thickness depending on the purpose. The thickness of the separator is, for example, 10 μm to 100 μm.

[0013] The peel strength of the separator is preferably 0.04 N / 50 mm to 0.5 N / 50 mm, and more preferably 0.07 N / 50 mm to 0.45 N / 50 mm. If the separator peel strength is within this range, the amount of adhesive chipping in the pressure-sensitive adhesive layer (particularly the pressure-sensitive adhesive layer in the profiled area) can be reduced. If the separator peel strength exceeds 0.5 N / 50 mm, the separator's releasability decreases, which can lead to process defects.

[0014] B. Optical Film The optical film may be a film composed of a single layer or a laminate. Specific examples of optical films composed of a single layer include window films, polarizers, and retardation films. Specific examples of optical films composed of a laminate include polarizing plates (typically, laminates of a polarizer and a protective film), conductive films for touch panels, surface-treated films, and laminates in which optical films composed of these single layers and / or optical films composed of laminates are appropriately laminated depending on the purpose (e.g., anti-reflection circular polarizing plates, polarizing plates with a conductive layer for touch panels). Polarizing plates and circular polarizing plates will be briefly described below as typical examples of optical films.

[0015] B-1. Polarizing plate A polarizing plate typically includes a polarizer and a protective layer provided on one or both sides of the polarizer.

[0016] B-1-1.Polarizer A polarizer is typically made of a resin film containing a dichroic material. Any appropriate resin film that can be used as a polarizer can be adopted as the resin film. A typical resin film is a polyvinyl alcohol resin (hereinafter referred to as a "PVA resin") film. The resin film may be a single-layer resin film or a laminate of two or more layers.

[0017] Specific examples of polarizers composed of a single-layer resin film include PVA-based resin films that have been subjected to a dyeing treatment with iodine and a stretching treatment (typically, uniaxial stretching). The dyeing with iodine is carried out, for example, by immersing the PVA-based film in an iodine aqueous solution. The stretching ratio in the uniaxial stretching is preferably 3 to 7 times. The stretching may be carried out after the dyeing treatment or while dyeing. Alternatively, the film may be dyed after stretching. If necessary, the PVA-based resin film may be subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, or the like. For example, by immersing the PVA-based resin film in water and washing it before dyeing, it is possible to clean off stains and antiblocking agents on the surface of the PVA-based film and also to swell the PVA-based resin film, thereby preventing uneven dyeing.

[0018] Specific examples of polarizers obtained using laminates include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying the resin substrate to form a PVA-based resin layer on the resin substrate, thereby obtaining a laminate of the resin substrate and the PVA-based resin layer, and then stretching and dyeing the laminate to convert the PVA-based resin layer into a polarizer. In this embodiment, stretching typically involves immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching can optionally further include in-air stretching the laminate at an elevated temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. The obtained resin substrate / polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate / polarizer laminate and any appropriate protective layer depending on the purpose may be laminated on the peeled surface. Details of such a polarizer manufacturing method are described in, for example, JP 2012-73580 A and Japanese Patent No. 6470455 A. The entire disclosures of these publications are incorporated herein by reference.

[0019] The thickness of the polarizer is preferably 25 μm or less, more preferably 1 μm to 12 μm, still more preferably 3 μm to 12 μm, and particularly preferably 3 μm to 8 μm. When the thickness of the polarizer is within this range, curling during heating can be well suppressed, and good appearance durability during heating can be obtained.

[0020] The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The single transmittance of the polarizer is preferably 43.0% to 46.0%, more preferably 44.5% to 46.0%. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.

[0021] B-1-2.Protective layer The protective layer is formed of any suitable film that can be used as a protective layer for a polarizer. Specific examples of materials that can be the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), and transparent resins such as polyesters, polyvinyl alcohols, polycarbonates, polyamides, polyimides, polyethersulfones, polysulfones, polystyrenes, polynorbornenes, polyolefins, (meth)acrylics, and acetates. Other examples include thermosetting or ultraviolet-curing resins such as (meth)acrylics, urethanes, (meth)acrylic urethanes, epoxy resins, and silicones. Other examples include glassy polymers such as siloxane polymers. Polymer films described in JP 2001-343529 A (WO 01 / 37007) can also be used. Examples of materials that can be used for this film include a resin composition containing a thermoplastic resin having substituted or unsubstituted imide groups in its side chains and a thermoplastic resin having substituted or unsubstituted phenyl and nitrile groups in its side chains, such as a resin composition containing an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer.The polymer film can be, for example, an extrusion molded product of the above resin composition.

[0022] The protective layer on the side opposite to the pressure-sensitive adhesive layer (outer protective layer) may be subjected to surface treatment such as hard coating treatment, anti-reflection treatment, anti-sticking treatment, anti-glare treatment, etc., as required.

[0023] In one embodiment, the protective layer on the pressure-sensitive adhesive layer side (inner protective layer) is preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane retardation Re(550) is 0 nm to 10 nm and the thickness direction retardation Rth(550) is -10 nm to +10 nm. In another embodiment, the inner protective layer may be a retardation film, a brightness enhancement film, a diffusion film, etc.

[0024] The protective layer may have any appropriate thickness. The thickness of the protective layer is preferably 5 μm to 200 μm, more preferably 15 μm to 45 μm, and even more preferably 20 μm to 40 μm. When a surface treatment is applied, the thickness of the protective layer includes the thickness of the surface treatment layer.

[0025] B-2.Circular polarizer A circular polarizing plate typically includes a polarizer and a retardation layer. In practice, the polarizer may be included in the circular polarizing plate as a polarizing plate with a protective layer on one or both sides. The retardation layer is typically disposed between the polarizing plate and the adhesive layer. The polarizer and the polarizing plate are as described in Section B-1 above.

[0026] The retardation layer may be a single layer or may have a laminated structure.

[0027] When the retardation layer is configured as a single layer, it can typically function as λ / 4. In this case, the in-plane retardation Re(550) of the retardation layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, and even more preferably 130 nm to 160 nm. The angle between the slow axis of the retardation layer and the absorption axis of the polarizer is preferably 40° to 50°, more preferably 42° to 48°, and even more preferably approximately 45°. The retardation layer may exhibit reverse dispersion wavelength characteristics in which the retardation value increases depending on the wavelength of the measurement light, positive wavelength dispersion characteristics in which the retardation value decreases depending on the wavelength of the measurement light, or flat wavelength dispersion characteristics in which the retardation value changes little depending on the wavelength of the measurement light. In one embodiment, the retardation layer exhibits reverse dispersion wavelength characteristics. In this case, Re(450) / Re(550) of the retardation layer is preferably 0.8 or more and less than 1, more preferably 0.8 or more and 0.95 or less.

[0028] When the retardation layer has a laminated structure, it typically has a two-layer structure consisting of a first retardation layer and a second retardation layer, in which case either the first retardation layer or the second retardation layer can function as a λ / 2 plate, and the other can function as a λ / 4 plate. For example, when the first retardation layer can function as a λ / 2 plate and the second retardation layer can function as a λ / 4 plate, the Re(550) of the first retardation layer is preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm, and even more preferably 250 nm to 280 nm, and the angle between its slow axis and the absorption axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, and even more preferably about 15°; the Re(550) of the second retardation layer 22 is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, and even more preferably 130 nm to 160 nm, and the angle between its slow axis and the absorption axis of the polarizer is preferably 70° to 80°, more preferably 72° to 78°, and even more preferably about 75°.

[0029] The retardation layer may be made of any suitable material as long as it satisfies the above-mentioned characteristics. For example, the retardation layer may be a resin film (typically a stretched film) or a liquid crystal compound alignment and solidification layer (liquid crystal alignment and solidification layer). Typical examples of resins constituting the resin film include polycarbonate-based resins, polyester carbonate-based resins, polyester-based resins, polyvinyl acetal-based resins, polyarylate-based resins, cyclic olefin-based resins, cellulose-based resins, polyvinyl alcohol-based resins, polyamide-based resins, polyimide-based resins, polyether-based resins, polystyrene-based resins, and acrylic-based resins. These resins may be used alone or in combination (e.g., blended or copolymerized). When the retardation layer is made of a resin film exhibiting reverse dispersion wavelength characteristics, polycarbonate-based resins or polyester carbonate-based resins (hereinafter sometimes simply referred to as polycarbonate-based resins) may be suitably used. Details of polycarbonate resins suitable for use in the retardation layer and methods for forming the retardation layer are described in, for example, JP 2014-10291 A, JP 2014-26266 A, JP 2015-212816 A, JP 2015-212817 A, and JP 2015-212818 A; specific examples of liquid crystal compounds and methods for forming the alignment solidification layer are described in, for example, JP 2006-163343 A. The descriptions in these publications are incorporated herein by reference.

[0030] C.Adhesive layer C-1. Characteristics of the adhesive layer As described above, the pressure-sensitive adhesive layer has a creep value at 85°C of 500 μm or less, preferably 5 μm to 500 μm. In one embodiment, the creep value is preferably 200 μm to 450 μm, and more preferably 220 μm to 420 μm. In another embodiment, the creep value is preferably 5 μm to 300 μm, more preferably 5 μm to 200 μm, even more preferably 10 μm to 100 μm, particularly preferably 15 μm to 70 μm, and especially preferably 20 μm to 50 μm. If the creep value is within this range, glue chipping in the irregularly processed portion can be significantly suppressed, and peeling in a high-temperature, high-humidity environment can be significantly suppressed. Even when the creep value is relatively large (for example, 200 μm or more), it is estimated that adhesive chipping can be suppressed by controlling the composition of the adhesive constituting the adhesive layer (for example, the type of base polymer (polarity, Tg, softness), molecular weight) and the crosslinking structure (for example, the type of crosslinking agent, the distance between crosslinking points (molecular weight between crosslinking points), crosslinking density, and the uncrosslinked component (sol content)). The creep value can be measured, for example, by the following procedure: A test sample cut out from an optical film with a pressure-sensitive adhesive layer is attached to a support plate at a bonding surface of 10 mm × 10 mm. With the support plate to which the test sample is attached being fixed, a load of 500 gf is applied vertically downward. The amount of deviation from the support plate is measured 1 second and 3600 seconds after the load is applied, and Cr1 and Cr2 are calculated, respectively. 3600 Let Cr1 and Cr 3600 The creep value is calculated by the following formula: ΔCr=Cr 3600 -Cr1

[0031] The pressure-sensitive adhesive layer preferably has a storage modulus at 85°C of 1.0 x 10 4 Pa or more, preferably 2.0 × 10 4 Pa or more, more preferably 5.0 × 10 4 Pa or more, and more preferably 1.0 × 10 5 If the storage modulus is in this range, the desired creep value can be easily achieved. On the other hand, the storage modulus is, for example, 3.0×10 6When the upper limit of the storage modulus is within this range, peeling of the pressure-sensitive adhesive layer in a high-temperature, high-humidity environment can be significantly suppressed.

[0032] The weight average molecular weight Mw (details will be described later) of the base polymer in the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer is, for example, 200,000 to 3,000,000, and preferably 1,000,000 to 2,500,000.

[0033] The gel fraction of the PSA layer is preferably 55% to 95%. In one embodiment, the gel fraction is preferably 60% to 93%, more preferably 80% to 91%. In this case, the weight-average molecular weight Mw (described below) of the high-molecular-weight component derived from the base polymer among the uncrosslinked components (sol components) of the PSA composition is, for example, 50,000 to 1,000,000, preferably 50,000 to 500,000, and more preferably 100,000 to 400,000. The gel fraction is determined by immersing the crosslinked PSA in a predetermined solvent (e.g., ethyl acetate) for 6 days and then drying, and is calculated as (dry weight after immersion / dry weight before immersion) × 100. The weight-average molecular weight Mw of the base polymer and the high-molecular-weight component derived from the base polymer among the uncrosslinked components (sol components) of the PSA composition can be determined, for example, by gel permeation chromatography (GPC) and calculated in terms of polystyrene.

[0034] The swelling degree of the pressure-sensitive adhesive layer is preferably 35 times or less, more preferably 10 to 30 times, even more preferably 11 to 28 times, and particularly preferably 12 to 20 times. If the swelling degree is within this range, glue chipping in the irregularly shaped processed portion can be significantly suppressed. The swelling degree is determined by immersing the crosslinked pressure-sensitive adhesive in a predetermined solvent (e.g., ethyl acetate) for 6 days and calculating (weight after immersion / dry weight after immersion).

[0035] The storage modulus, gel fraction, and swelling degree of the pressure-sensitive adhesive layer can be controlled by adjusting the composition of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer (e.g., the type (polarity, Tg, softness), and molecular weight of the base polymer), the crosslinking structure (e.g., the type of crosslinking agent, the distance between crosslinking points (molecular weight between crosslinking points), and the crosslinking density). More specifically, the type and combination of monomer components of the base polymer, the polymerization conditions for the base polymer, the type and amount of crosslinking agent used, etc. can be appropriately set.

[0036] The thickness of the adhesive layer is preferably 2 μm to 55 μm, more preferably 2 μm to 30 μm, even more preferably 2 μm to 20 μm, and particularly preferably 5 μm to 15 μm. If the thickness of the adhesive layer is within this range, glue chipping in the irregularly shaped processed portion can be significantly suppressed due to a synergistic effect with the effect of controlling the creep value.

[0037] The pressure-sensitive adhesive layer is typically formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer, a urethane polymer, a silicone polymer, or a rubber polymer as a base polymer. When a (meth)acrylic polymer is used as the base polymer, the pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing, for example, a (meth)acrylic polymer (A). The (meth)acrylic polymer (A) contains an alkyl (meth)acrylate as a main component.

[0038] C-2. (Meth)acrylic polymer (A) As described above, the (meth)acrylic polymer (A) contains alkyl (meth)acrylate as a main component. From the viewpoint of improving the adhesiveness of the pressure-sensitive adhesive layer, the alkyl (meth)acrylate preferably accounts for 50% by weight or more of all monomer components forming the (meth)acrylic polymer (A), and can be arbitrarily set as the remainder of the monomers other than the alkyl (meth)acrylate. Here, (meth)acrylate refers to acrylate and / or methacrylate.

[0039] The alkyl (meth)acrylate constituting the main skeleton of the (meth)acrylic polymer (A) may be a linear or branched alkyl group having 1 to 18 carbon atoms. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, hexyl, cyclohexyl, heptyl, 2-ethylhexyl, isooctyl, nonyl, decyl, isodecyl, dodecyl, isomyristyl, lauryl, tridecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl groups. The alkyl (meth)acrylates may be used alone or in combination. The average number of carbon atoms in the alkyl group is preferably 3 to 10.

[0040] The (meth)acrylic polymer (A) may contain, as a monomer component, a copolymerizable monomer such as a carboxyl group-containing monomer (a1) or a hydroxyl group-containing monomer (a2) in addition to the alkyl (meth)acrylate. The copolymerizable monomers may be used alone or in combination.

[0041] The carboxyl group-containing monomer (a1) is a compound containing a carboxyl group and a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group in its structure. Examples of the carboxyl group-containing monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Among these, acrylic acid is preferred from the viewpoints of copolymerizability, cost, and improving the adhesive properties of the adhesive layer.

[0042] When a carboxyl group-containing monomer (a1) is used as a monomer component, the content of the carboxyl group-containing monomer (a1) is usually 0.01% by weight or more and 10% by weight or less of the total monomer components forming the (meth)acrylic polymer (A).

[0043] The hydroxyl group-containing monomer (a2) is a compound containing a hydroxyl group and a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group in its structure. Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate; and (4-hydroxymethylcyclohexyl)-methyl acrylate. Among these, from the viewpoint of improving the durability of the pressure-sensitive adhesive layer, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred, and 4-hydroxybutyl (meth)acrylate is more preferred.

[0044] When the hydroxyl group-containing monomer (a2) is used as a monomer component, the content of the hydroxyl group-containing monomer (a2) is usually 0.01% by weight or more and 10% by weight or less of the total monomer components forming the (meth)acrylic polymer (A).

[0045] The (meth)acrylic polymer (A) preferably contains, as a monomer component, a monomer having an unsaturated carbon-carbon double bond that results in a homopolymer having a glass transition temperature of 0°C or higher. Examples of the monomer (a3) ​​having an unsaturated carbon-carbon double bond that results in a homopolymer having a glass transition temperature of 0°C or higher include alkyl (meth)acrylate monomers and (meth)acrylic acid. The monomer (a3) ​​is preferably a monomer having an unsaturated carbon-carbon double bond that results in a homopolymer having a glass transition temperature of 20°C or higher, and more preferably a monomer having an unsaturated carbon-carbon double bond that results in a homopolymer having a glass transition temperature of 40°C or higher.

[0046] The content of the monomer (a3) ​​in the (meth)acrylic polymer (A) is not particularly limited. The content is usually 0.1% by weight to 40% by weight, more preferably 1% by weight to 30% by weight. When two or more types of monomer (a3) ​​are used in combination, the content is the total content.

[0047] Examples of the monomer (a3) ​​include methyl acrylate (Tg: 8°C), methyl methacrylate (Tg: 105°C), ethyl methacrylate (Tg: 65°C), n-propyl acrylate (Tg: 3°C), n-propyl methacrylate (Tg: 35°C), n-pentyl acrylate (Tg: 22°C), n-tetradecyl acrylate (Tg: 24°C), n-hexadecyl acrylate (Tg: 35°C), n-hexadecyl methacrylate (Tg: 15°C), n-stearyl acrylate (Tg: 30°C), and n-stearyl methacrylate (Tg: 38°C). Examples of suitable alkyl (meth)acrylates include linear alkyl (meth)acrylates, branched alkyl (meth)acrylates such as t-butyl acrylate (Tg: 43° C.), t-butyl methacrylate (Tg: 48° C.), i-propyl methacrylate (Tg: 81° C.), and i-butyl methacrylate (Tg: 48° C.), cyclic alkyl (meth)acrylates such as cyclohexyl acrylate (Tg: 19° C.), cyclohexyl methacrylate (Tg: 65° C.), isobornyl acrylate (Tg: 94° C.), and isobornyl methacrylate (Tg: 180° C.), and acrylic acid (Tg: 106° C.). These may be used alone or in combination.

[0048] When the pressure-sensitive adhesive composition contains a crosslinking agent described below, the copolymerizable monomer serves as a reaction site with the crosslinking agent. Carboxyl group-containing monomers and hydroxyl group-containing monomers are highly reactive with the intermolecular crosslinking agent, and are therefore preferably used to improve the cohesiveness and heat resistance of the resulting pressure-sensitive adhesive layer. In addition, carboxyl group-containing monomers are preferred in terms of achieving both durability and reworkability, and hydroxyl group-containing monomers are preferred in terms of improving reworkability.

[0049] Other copolymerizable monomers (a4) may be further used as monomer components. The other copolymerizable monomers (a4) have a polymerizable functional group with an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group. By using the other copolymerizable monomers (a4), the adhesive properties and heat resistance of the pressure-sensitive adhesive layer can be improved. The other copolymerizable monomers (a4) can be used alone or in combination.

[0050] The adhesiveness of the pressure-sensitive adhesive layer can be improved by using an amino group-containing monomer or an amide group-containing monomer as the other copolymerizable monomer (a4). Examples of the amino group-containing monomer include N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate. Examples of the amide group-containing monomer include acrylamide-based monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, N-methyl(meth)acrylamide, N-butyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylol-N-propane(meth)acrylamide, aminomethyl(meth)acrylamide, aminoethyl(meth)acrylamide, mercaptomethyl(meth)acrylamide, and mercaptoethyl(meth)acrylamide; N-acryloyl heterocyclic monomers such as N-(meth)acryloylmorpholine, N-(meth)acryloylpiperidine, and N-(meth)acryloylpyrrolidine; and N-vinyl group-containing lactam-based monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam.

[0051] The other copolymerizable monomer (a4) may be a polyfunctional monomer. The use of a polyfunctional monomer allows for adjustment of the gel fraction and control of the cohesive strength of the pressure-sensitive adhesive layer. Examples of polyfunctional monomers include polyfunctional acrylates such as hexanediol di(meth)acrylate (1,6-hexanediol di(meth)acrylate), butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, epoxy acrylate, polyester acrylate, and urethane acrylate; and divinylbenzene. The polyfunctional acrylate is preferably 1,6-hexanediol diacrylate or dipentaerythritol hexa(meth)acrylate.

[0052] Examples of the other copolymerizable monomers (a4), in addition to those mentioned above, include (meth)acrylic acid alkoxyalkyl esters such as 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, and 4-ethoxybutyl (meth)acrylate; cyclopolymerizable monomers such as methyl 2-(allyloxymethyl)acrylate; epoxy group-containing monomers such as glycidyl (meth)acrylate and methylglycidyl (meth)acrylate; and sulfonic acid group-containing monomers such as sodium vinyl sulfonate. monomers; phosphate group-containing monomers; (meth)acrylic acid esters having an alicyclic hydrocarbon group such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; (meth)acrylic acid esters having an aromatic hydrocarbon group such as phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate; vinyl esters such as vinyl acetate and vinyl propionate; aromatic vinyl compounds such as styrene and vinyl toluene; olefins or dienes such as ethylene, propylene, butadiene, isoprene, and isobutylene; vinyl ethers such as vinyl alkyl ethers; and vinyl chloride can be used.

[0053] The content of the other copolymerizable monomer (a4) in the (meth)acrylic polymer is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 8% by mass or less, and particularly preferably 5% by mass or less.

[0054] C-3. Method for producing (meth)acrylic polymer (A) The (meth)acrylic polymer (A) can be produced by any appropriate method. Specific examples of the production method include radiation polymerization using electron beams, UV rays, etc., and various radical polymerizations such as solution polymerization, bulk polymerization, and emulsion polymerization. The resulting (meth)acrylic polymer (A) may be any of a random copolymer, a block copolymer, a graft copolymer, etc.

[0055] In solution polymerization, for example, ethyl acetate or toluene is used as a polymerization solvent. The reaction in solution polymerization is carried out by adding a polymerization initiator to the monomer components under a stream of an inert gas such as nitrogen, and usually at about 50°C to 70°C for about 5 hours to 30 hours.

[0056] The polymerization initiator, chain transfer agent, emulsifier, etc. used in the radical polymerization can be appropriately selected depending on the purpose. The weight average molecular weight of the (meth)acrylic polymer (A) can be controlled by the amounts of the polymerization initiator and chain transfer agent used and the reaction conditions, and the types and amounts used can be adjusted depending on the desired weight average molecular weight.

[0057] Examples of the polymerization initiator include azo initiators such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis(2-methylpropionamidine) disulfate, 2,2'-azobis(N,N'-dimethyleneisobutylamidine), and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate (VA-057, manufactured by Wako Pure Chemical Industries, Ltd.); persulfates such as potassium persulfate and ammonium persulfate; di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec- Examples of the initiator include peroxide initiators such as butyl peroxydicarbonate, t-butyl peroxyneodecanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, dibenzoyl peroxide, t-butyl peroxyisobutyrate, 1,1-di(t-hexylperoxy)cyclohexane, t-butyl hydroperoxide, and hydrogen peroxide; and redox initiators that combine a peroxide with a reducing agent, such as a combination of a persulfate and sodium hydrogen sulfite, or a combination of a peroxide and sodium ascorbate.

[0058] The polymerization initiators can be used alone or in combination. The total amount of the polymerization initiators used is preferably about 0.005 to 1 part by weight, and more preferably about 0.01 to 0.5 parts by weight, per 100 parts by weight of the monomer components.

[0059] Examples of chain transfer agents include lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, and 2,3-dimercapto-1-propanol. The chain transfer agents may be used alone or in combination. The total amount of chain transfer agents used is approximately 0.1 parts by weight or less per 100 parts by weight of the monomer components.

[0060] Examples of emulsifiers used in emulsion polymerization include anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, polyoxyethylene alkyl ether ammonium sulfate, and polyoxyethylene alkyl phenyl ether sodium sulfate, and nonionic emulsifiers such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene fatty acid esters, and polyoxyethylene-polyoxypropylene block polymers. These emulsifiers can be used alone or in combination.

[0061] Examples of reactive emulsifiers include emulsifiers having a radically polymerizable functional group such as a propenyl group or an allyl ether group introduced therein. Specific examples include Aqualon HS-10, HS-20, KH-10, BC-05, BC-10, and BC-20 (all manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and Adeka Reasoap SE10N (manufactured by ADEKA Corporation). Reactive emulsifiers are preferred because they are incorporated into the polymer chain after polymerization, improving water resistance. The amount of emulsifier used is preferably 0.3 to 5 parts by weight, more preferably 0.5 to 1 part by weight, per 100 parts by weight of the total amount of monomer components. When the amount of emulsifier used falls within this range, the polymerization stability and the mechanical stability of the resulting pressure-sensitive adhesive layer are excellent.

[0062] When the (meth)acrylic polymer (A) is produced by radiation polymerization, it can be produced by polymerizing the monomer components by irradiating them with radiation such as electron beams or UV. When the radiation polymerization is carried out by UV polymerization, a photopolymerization initiator can be added to the monomer components, which can shorten the polymerization time. When the radiation polymerization is carried out by electron beams, it is not particularly necessary to add a photopolymerization initiator to the monomer components.

[0063] Any appropriate photopolymerization initiator can be used as the photopolymerization initiator. Specific examples include benzoin ether-based, acetophenone-based, α-ketol-based, photoactive oxime-based, benzoin-based, benzil-based, benzophenone-based, ketal-based, and thioxanthone-based photopolymerization initiators. The amount of the photopolymerization initiator used is preferably 0.02 to 1.5 parts by weight, more preferably 0.1 to 1 part by weight, per 100 parts by weight of the total amount of the monomer components. The photopolymerization initiators can be used alone or in combination.

[0064] As described above, the weight-average molecular weight Mw of the (meth)acrylic polymer (A) is, for example, 200,000 to 3,000,000, preferably 1,000,000 to 2,500,000, and more preferably 1,200,000 to 2,500,000. When the weight-average molecular weight Mw is within this range, a pressure-sensitive adhesive layer with excellent durability (particularly heat resistance) can be obtained. If the weight-average molecular weight Mw exceeds 3,000,000, an increase in viscosity and / or gelation during polymer polymerization may occur.

[0065] The polydispersity (weight-average molecular weight (Mw) / number-average molecular weight (Mn)) of the (meth)acrylic polymer (A) is preferably 5.0 or less, more preferably 1.05 to 5.0, and even more preferably 1.05 to 4.0. When the polydispersity (Mw / Mn) is high (e.g., greater than 5.0), the adhesive layer contains a large amount of low-molecular-weight polymers. Even if the adhesive layer is formed to achieve the same creep value, the amount of uncrosslinked polymers and oligomers (sol components) will be large, reducing the toughness (weakness) of the adhesive layer and potentially causing adhesive chipping during processing into profile shapes or peeling under high-temperature, high-humidity conditions. The polydispersity (Mw / Mn), like the weight-average molecular weight, can be measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene.

[0066] C-4. Silane coupling agents containing reactive functional groups The pressure-sensitive adhesive composition may contain a reactive functional group-containing silane coupling agent. The reactive functional group of the reactive functional group-containing silane coupling agent is typically a functional group other than an acid anhydride group. Examples of functional groups other than an acid anhydride group include epoxy groups, mercapto groups, amino groups, isocyanate groups, isocyanurate groups, vinyl groups, styryl groups, acetoacetyl groups, ureido groups, thiourea groups, (meth)acrylic groups, heterocyclic groups, and combinations thereof. The reactive functional group-containing silane coupling agents may be used alone or in combination.

[0067] Examples of reactive functional group-containing silane coupling agents include epoxy group-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; mercapto group-containing silane coupling agents such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane; 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and 3-triethoxysilane; Examples of suitable silane coupling agents include amino group-containing silane coupling agents such as N-(1,3-dimethylbutylidene)propylamine and N-phenyl-γ-aminopropyltrimethoxysilane; isocyanate group-containing silane coupling agents such as 3-isocyanatepropyltriethoxysilane; vinyl group-containing silane coupling agents such as vinyltrimethoxysilane and vinyltriethoxysilane; styryl group-containing silane coupling agents such as p-styryltrimethoxysilane; and (meth)acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane. Among these, epoxy group-containing silane coupling agents and mercapto group-containing silane coupling agents are preferred. An example of an epoxy group-containing silane coupling agent commercially available is "KBM-403" manufactured by Shin-Etsu Chemical Co., Ltd.

[0068] As the reactive functional group-containing silane coupling agent, those having multiple alkoxysilyl groups in the molecule (oligomeric silane coupling agents) can also be used. Specific examples include epoxy group-containing oligomeric silane coupling agents manufactured by Shin-Etsu Chemical Co., Ltd., trade names "X-41-1053," "X-41-1059A," "X-41-1056," and "X-40-2651," and mercapto group-containing oligomeric silane coupling agents "X-41-1818," "X-41-1810," and "X-41-1805." Oligomeric silane coupling agents are less likely to volatilize, and because they have multiple alkoxysilyl groups, they can be effective in improving durability.

[0069] When a reactive functional group-containing silane coupling agent is blended into the pressure-sensitive adhesive composition, the amount of the reactive functional group-containing silane coupling agent blended is usually 0.001 parts by weight or more and 5 parts by weight or less per 100 parts by weight of the (meth)acrylic polymer (A).

[0070] C-5. Crosslinking Agent The pressure-sensitive adhesive composition may contain a crosslinking agent. Examples of crosslinking agents that can be used include organic crosslinking agents and polyfunctional metal chelates. Examples of organic crosslinking agents include isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, and imine crosslinking agents. Polyfunctional metal chelates are compounds in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, and Ti. Examples of atoms in the organic compound that form covalent or coordinate bonds include oxygen atoms, and examples of organic compounds include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds. Furthermore, when the pressure-sensitive adhesive composition is radiation-curable, a polyfunctional monomer can be used as the crosslinking agent. Examples of polyfunctional monomers include polyfunctional acrylates such as hexanediol di(meth)acrylate (1,6-hexanediol di(meth)acrylate), butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, epoxy acrylate, polyester acrylate, and urethane acrylate; and divinylbenzene. Polyfunctional acrylates are preferably 1,6-hexanediol diacrylate and dipentaerythritol hexa(meth)acrylate. The crosslinking agents may be used alone or in combination.

[0071] When the pressure-sensitive adhesive composition is a solvent-based composition, the crosslinking agent is preferably an isocyanate-based crosslinking agent and / or a peroxide-based crosslinking agent, and from the viewpoint of reducing adhesive chipping during processing, an isocyanate-based crosslinking agent is particularly preferred, and from the viewpoint of suppressing peeling in high-temperature, high-humidity environments, it is more preferred to use an isocyanate-based crosslinking agent and a peroxide-based crosslinking agent in combination.

[0072] As the isocyanate-based crosslinking agent, for example, a compound having at least two isocyanate groups (including isocyanate-regenerating functional groups in which the isocyanate groups are temporarily protected by a blocking agent or oligomerization, etc.) can be used. For example, any suitable aliphatic polyisocyanate, alicyclic polyisocyanate, aromatic polyisocyanate, etc. that can be used in a urethanization reaction can be used.

[0073] Examples of aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0074] Examples of alicyclic isocyanates include 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated tetramethylxylylene diisocyanate.

[0075] Examples of aromatic diisocyanates include phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, and xylylene diisocyanate.

[0076] Other examples of isocyanate-based crosslinking agents include polymers (dimers, trimers, pentamers, etc.) of the above diisocyanates, urethane-modified products obtained by reacting with polyhydric alcohols such as trimethylolpropane, urea-modified products, biuret-modified products, alphanate-modified products, isocyanurate-modified products, and carbodiimide-modified products.

[0077] Examples of commercially available isocyanate crosslinking agents include products manufactured by Tosoh Corporation under the trade names "Millionate MT," "Millionate MTL," "Millionate MR-200," "Millionate MR-400," "Coronate L," "Coronate HL," and "Coronate HX," and products manufactured by Mitsui Chemicals, Inc. under the trade names "Takenate D-110N," "Takenate D-120N," "Takenate D-140N," "Takenate D-160N," "Takenate D-165N," "Takenate D-170HN," "Takenate D-178N," "Takenate 500," and "Takenate 600."

[0078] As the isocyanate-based crosslinking agent, aromatic polyisocyanates and their modified aromatic polyisocyanate compounds, and aliphatic polyisocyanates and their modified aliphatic polyisocyanate compounds are preferred. Aromatic polyisocyanate-based compounds are preferably used because they have a good balance between crosslinking rate and pot life. As the aromatic polyisocyanate-based compound, tolylene diisocyanate and its modified compounds are particularly preferred.

[0079] Any appropriate peroxide-based crosslinking agent can be used as long as it generates radical active species upon heating or light irradiation to promote crosslinking of the base polymer ((meth)acrylic polymer (A)) of the pressure-sensitive adhesive composition. Peroxides having a one-minute half-life temperature of 80°C to 160°C are preferred, and peroxides having a one-minute half-life temperature of 90°C to 140°C are more preferred. Such peroxides have excellent workability and stability.

[0080] Examples of the peroxides include di(2-ethylhexyl)peroxydicarbonate (1-minute half-life temperature: 90.6°C), di(4-t-butylcyclohexyl)peroxydicarbonate (1-minute half-life temperature: 92.1°C), di-sec-butylperoxydicarbonate (1-minute half-life temperature: 92.4°C), t-butylperoxyneodecanoate (1-minute half-life temperature: 103.5°C), t-hexylperoxypivalate (1-minute half-life temperature: 109.1°C), t-butylperoxypivalate (1-minute half-life temperature: 110.3°C), dilauroylperoxy Examples include di(4-t-butylcyclohexyl)peroxide (1-minute half-life temperature: 116.4°C), di-n-octanoyl peroxide (1-minute half-life temperature: 117.4°C), 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (1-minute half-life temperature: 124.3°C), di(4-methylbenzoyl)peroxide (1-minute half-life temperature: 128.2°C), dibenzoyl peroxide (1-minute half-life temperature: 130.0°C), t-butylperoxyisobutyrate (1-minute half-life temperature: 136.1°C), and 1,1-di(t-hexylperoxy)cyclohexane (1-minute half-life temperature: 149.2°C). Among these, di(4-t-butylcyclohexyl)peroxydicarbonate, dilauroyl peroxide, and dibenzoyl peroxide are preferred because of their particularly excellent crosslinking reaction efficiency.

[0081] The half-life of a peroxide is an index that indicates the decomposition rate of the peroxide, and refers to the time it takes for the remaining amount of peroxide to be reduced to half. The decomposition temperature required to obtain the half-life at any time and the half-life time at any temperature are listed in manufacturer catalogs, for example, in NOF Corporation's "Organic Peroxide Catalog, 9th Edition (May 2003)."

[0082] When a crosslinking agent is blended into the pressure-sensitive adhesive composition, the amount of the crosslinking agent blended is usually 0.01 to 15 parts by weight per 100 parts by weight of the (meth)acrylic polymer (A).

[0083] When an isocyanate crosslinking agent is blended into the pressure-sensitive adhesive composition, the amount of the isocyanate crosslinking agent blended is usually 0.01 to 15 parts by weight per 100 parts by weight of the (meth)acrylic polymer.

[0084] When a peroxide is blended into the pressure-sensitive adhesive composition, the blending amount of the peroxide is usually 0.01 to 2 parts by weight per 100 parts by weight of the (meth)acrylic polymer. Within this range, it is easy to adjust the processability, crosslinking stability, etc.

[0085] C-6. Other ingredients The pressure-sensitive adhesive composition may contain a (meth)acrylic oligomer. The (meth)acrylic oligomer can be obtained by polymerizing one or more of the monomer components described in Section C-2 regarding the (meth)acrylic polymer. The type, number, combination, and polymerization molar ratio of the monomer components can be appropriately set depending on the purpose, desired properties, etc. The weight-average molecular weight Mw of the (meth)acrylic oligomer is preferably 1,000 to 8,000, more preferably 2,000 to 7,000, and even more preferably 3,000 to 6,000. When the (meth)acrylic oligomer is blended into the pressure-sensitive adhesive composition, the blending amount of the (meth)acrylic oligomer is preferably 5 to 35 parts by weight per 100 parts by weight of the (meth)acrylic polymer.

[0086] The pressure-sensitive adhesive composition may contain an ionic compound. Any appropriate ionic compound may be used as the ionic compound. Examples of ionic compounds include those described in JP 2015-4861 A. Among these, (perfluoroalkylsulfonyl)imide lithium salt is preferred, and bis(trifluoromethanesulfonylimide)lithium is more preferred. The amount of the ionic compound may be appropriately set depending on the purpose. For example, the amount of the ionic compound is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, even more preferably 3 parts by weight or less, and particularly preferably 1 part by weight or less, per 100 parts by weight of the (meth)acrylic polymer (A).

[0087] The pressure-sensitive adhesive composition may contain additives. Specific examples of additives include colorants, powders such as pigments, dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, antioxidants, antiaging agents, light stabilizers, UV absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particles, and foil-like materials. Furthermore, a redox system may be used by adding a reducing agent within a controllable range. The type, number, combination, and content of additives may be appropriately determined depending on the purpose. The content of the additive is preferably 5 parts by weight or less, more preferably 3 parts by weight or less, and even more preferably 1 part by weight or less, per 100 parts by weight of the (meth)acrylic polymer (A).

[0088] D. Image display device As described above, the pressure-sensitive adhesive layer-attached optical film according to an embodiment of the present invention can be suitably applied to an image display device. Accordingly, an image display device including a pressure-sensitive adhesive layer-attached optical film is also encompassed in an embodiment of the present invention. The image display device typically includes an image display cell and a pressure-sensitive adhesive layer-attached optical film bonded to the image display cell via a pressure-sensitive adhesive layer. Examples of image display devices include liquid crystal display devices, organic electroluminescence (EL) display devices, and quantum dot display devices. Organic EL display devices are preferred, as the effects of the pressure-sensitive adhesive layer-attached optical film are significant. [Example]

[0089] The present invention will be specifically described below using examples, but the present invention is not limited to these examples. The evaluation items in the examples are as follows. Unless otherwise specified, "parts" and "%" in the examples are by weight.

[0090] (1) Gel fraction The adhesives used in the examples and comparative examples were crosslinked, immersed in ethyl acetate for 6 days, and then dried. The gel fraction (%) was calculated using the following formula. Gel fraction (%) = (dry weight after immersion / dry weight before immersion) × 100 (2) Swelling degree The adhesives used in the examples and comparative examples were crosslinked and immersed in ethyl acetate for 6 days. The swelling degree (%) was calculated using the following formula. Swelling ratio (times) = weight after immersion / dry weight after immersion (3) Separator peeling force The pressure-sensitive adhesive layer-attached optical film (before profile processing) used in the examples and comparative examples was cut into a size of 50 mm × 150 mm to prepare a measurement sample. Using a tensile tester (Autograph SHIMAZU AG-1 50N), the separator was peeled from the measurement sample at a pulling angle of 180° and a pulling rate of 300 mm / min, and the peel strength of the separator was measured. (4) Creep value The pressure-sensitive adhesive layer-attached optical films obtained in the Examples and Comparative Examples were cut into 10 mm x 30 mm pieces to prepare test samples. The upper end portion of each test sample (10 mm x 10 mm) was attached to a SUS plate via the pressure-sensitive adhesive layer, and autoclaved for 15 minutes at 50°C and 5 atmospheres. A precision hot plate, with its heating surface oriented vertically, was heated to 85°C, and the SUS plate with the pressure-sensitive adhesive layer-attached optical film attached was placed so that the side without the pressure-sensitive adhesive layer was in contact with the heating surface of the hot plate. After heating the SUS plate at 85°C for 5 minutes, a load of 500 gf was applied vertically downward to the lower end of the pressure-sensitive adhesive layer-attached polarizing film. The amount of deviation between the pressure-sensitive adhesive layer-attached optical film and the SUS plate was measured 1 second and 3600 seconds after the load was applied, resulting in Cr1 and Cr3600 Cr1 and Cr 3600 The creep value was determined as ΔCr by the following formula: ΔCr=Cr 3600 -Cr1 (5) Amount of glue missing The cross-sectional state of the adhesive layer in the contoured portion of the adhesive layer-attached optical film obtained in the examples and comparative examples was observed with an optical microscope, and the length of the portion where the adhesive layer was missing the most from the outer edge inward in the surface direction was measured, and this length was taken as the amount of glue missing (μm). (6)Durability The pressure-sensitive adhesive layer-attached optical films obtained in the Examples and Comparative Examples were cut into test samples measuring 300 mm x 220 mm. The cutouts were performed so that the absorption axis of the polarizer was aligned along the long side. These test samples were then attached to alkali-free glass (manufactured by Corning Incorporated, product name "EG-XG") measuring 350 mm x 250 mm x 0.7 mm thick using a laminator. The test samples were then autoclaved at 50°C and 0.5 MPa for 15 minutes to adhere the pressure-sensitive adhesive layer to the glass. The test samples thus treated were then subjected to a 500-hour treatment in an atmosphere of 60°C / 95% RH. The appearance of the test samples after treatment was visually evaluated according to the following criteria. ○: No change in appearance such as foaming or peeling was observed. △: There is slight peeling or bubbling at the edge, but this does not pose a problem in practical use. ×: Significant peeling at the edge, causing problems in practical use.

[0091] <Production Example 1: Preparation of Acrylic Polymer A1> A four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser was charged with a monomer mixture containing 99 parts of butyl acrylate and 1 part of 4-hydroxybutyl acrylate. Furthermore, 0.1 parts of 2,2'-azobisisobutyronitrile as a polymerization initiator and 100 parts of ethyl acetate were charged to 100 parts of this monomer mixture. Nitrogen gas was introduced with gentle stirring to replace the atmosphere, and the liquid temperature in the flask was maintained at around 55°C, allowing the polymerization reaction to proceed for 8 hours to prepare a solution of acrylic polymer A1 with a weight average molecular weight (Mw) of 1.8 million and Mw / Mn = 4.8.

[0092] <Production Example 2: Preparation of Acrylic Polymer A2> A solution of acrylic polymer A2 having Mw of 2,300,000 and Mw / Mn = 3.9 was prepared in the same manner as in Production Example 1, except that a monomer mixture containing 94.9 parts of butyl acrylate, 0.1 parts of 2-hydroxyethyl acrylate, and 5 parts of acrylic acid was used.

[0093] <Production Example 3: Preparation of acrylic polymer (monomer partial polymer) A3> A four-neck flask equipped with a thermometer, nitrogen gas inlet tube, condenser, and a spindle connected to a Brookfield viscometer (rotational viscometer) was charged with a monomer mixture containing 65 parts of 2-ethylhexyl acrylate, 15 parts of N-vinylpyrrolidone, and 20 parts of 2-hydroxyethyl acrylate. Furthermore, 0.05 parts each of the photopolymerization initiators Omnirad 651 and Omnirad 184 were added to 100 parts of this monomer mixture. Next, nitrogen gas was introduced into the flask while rotating the spindle to replace the atmosphere with nitrogen. Photopolymerization was then carried out by irradiating with ultraviolet light until the viscosity of the polymerization system measured by the viscometer reached approximately 15 Pa·s, yielding acrylic polymer A3 containing a partial polymerization product of the monomer groups. The viscometer used was a Toki Sangyo BH model, with the spindle (rotor No. 5) rotating at 10 rpm. The liquid temperature in the flask was maintained at 30°C.

[0094] <Production Example 4: Preparation of Acrylic Polymer A4> A solution of acrylic polymer A4 having a Mw of 2,700,000 and a Mw / Mn of 3.8 was prepared in the same manner as in Production Example 1, except that a monomer mixture containing 91 parts of butyl acrylate, 6 parts of N-acryloylmorpholine, 0.3 parts of 4-hydroxybutyl acrylate, and 2.7 parts of acrylic acid was used.

[0095] <Production Example 5: Preparation of Acrylic Polymer A5> A solution of acrylic polymer A5 having Mw of 1,540,000 and Mw / Mn=2.8 was prepared in the same manner as in Production Example 1, except that the polymerization time was changed to 2 hours.

[0096] <Production Example 6: Preparation of acrylic oligomer B1> A four-neck flask equipped with a stirring blade, thermometer, nitrogen gas inlet, and condenser was charged with a monomer mixture containing 95 parts butyl acrylate, 2 parts acrylic acid, and 3 parts methyl acrylate. 100 parts of this monomer mixture were then charged with 0.1 parts 2,2'-azobisisobutyronitrile as a polymerization initiator and 140 parts toluene. Nitrogen gas was introduced with gentle stirring to thoroughly replace the atmosphere. The temperature in the flask was maintained at around 70°C, and the polymerization reaction was carried out for 8 hours to prepare a solution of acrylic oligomer B1. The oligomer had a Mw of 4500.

[0097] <Production Example 7: Preparation of acrylic oligomer B2> A monomer mixture containing 60 parts of dicyclopentanyl methacrylate and 40 parts of methyl methacrylate, 3.5 parts of α-thioglycerol as a chain transfer agent, and 100 parts of toluene as a polymerization solvent were mixed and stirred under a nitrogen atmosphere at 70°C for 1 hour. Next, 0.2 parts of AIBN was added as a thermal polymerization initiator, and the mixture was reacted at 70°C for 2 hours, then heated to 80°C and reacted for 2 hours. The reaction solution was then heated to 130°C, and the toluene, chain transfer agent, and unreacted monomers were dried and removed to obtain (meth)acrylic oligomer B2.

[0098] <Production Example 8: Preparation of polarizing plate> (Preparation of HC-added TAC film) A resin solution (DIC Corporation, product name: Unidic 17-806, solids concentration: 80%) containing a UV-curable resin monomer or oligomer primarily composed of urethane acrylate dissolved in butyl acetate was prepared. Five parts of a photopolymerization initiator (BASF Ltd., product name: IRGACURE 907) and 0.1 parts of a leveling agent (DIC Corporation, product name: GRANDIC PC4100) were added per 100 parts of solids in the solution. Cyclopentanone and propylene glycol monomethyl ether were added in a 45:55 ratio to the solution to adjust the solids concentration to 36%, thereby preparing a hard coat layer-forming material. This hard coat layer-forming material was applied to a TAC film (Fujifilm Corporation, product name: TJ40UL, thickness: 40 μm) to form a coating film, resulting in a hard coat layer thickness of 7 μm after curing. The coating was dried at 90°C for 1 minute and then irradiated with a high-pressure mercury lamp at an integrated light intensity of 300 mJ / cm 2 The coating film was cured by irradiating it with ultraviolet light to form a hard coat layer, and the resulting HC-added TAC film was then subjected to a saponification treatment.

[0099] (Preparation of polarizing plate) A 45 μm-thick polyvinyl alcohol film was stretched 3 times between rolls with different speed ratios while dyeing in a 0.3% iodine solution at 30°C for 1 minute. It was then immersed in an aqueous solution containing 4% boric acid and 10% potassium iodide at 60°C for 0.5 minutes, resulting in a total stretch ratio of 6 times. The film was then washed by immersion in an aqueous solution containing 1.5% potassium iodide at 30°C for 10 seconds, and then dried at 50°C for 4 minutes to obtain an 18 μm-thick polarizer. A polarizing plate was produced by bonding the HC-attached TAC film obtained above to one side of the polarizer and a saponified 40 μm-thick TAC film (KC4CT, manufactured by Konica Minolta) to the other side using a polyvinyl alcohol-based adhesive.

[0100] Example 1 (Preparation of Pressure-Sensitive Adhesive Composition) A solution of an acrylic pressure-sensitive adhesive composition was prepared by blending 30 parts of the acrylic oligomer B1 (solid content) obtained in Production Example 4, 0.02 parts of an isocyanate crosslinking agent (manufactured by Tosoh Corporation, trade name "Takenate D110N", trimethylolpropane / xylylene diisocyanate adduct), 1 part of a peroxide crosslinking agent (manufactured by Nippon Oil & Fats Corporation, trade name "Niper BMT"), and 0.2 parts of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403") with 100 parts of the solid content of the solution of acrylic polymer A1 obtained in Production Example 1.

[0101] (Preparation of polarizing plate with adhesive layer) The solution of the acrylic pressure-sensitive adhesive composition obtained above was applied to one side of a polyethylene terephthalate film (Mitsubishi Chemical Polyester Film Co., Ltd., product name "MRF38", separator film) treated with a silicone-based release agent so that the thickness of the pressure-sensitive adhesive layer after drying would be 50 μm, and the coating was dried at 155°C for 1 minute to form a pressure-sensitive adhesive layer on the surface of the separator film. Next, the pressure-sensitive adhesive layer formed on the separator film was attached to the TAC film (KC4CT) side of the polarizing plate produced in Production Example 8 to produce a pressure-sensitive adhesive layer-attached optical film (pressure-sensitive adhesive layer-attached polarizing plate). The obtained pressure-sensitive adhesive layer-attached optical film was subjected to profile processing. In this process, a laminate in which a surface protective film (Nitto Denko Corporation, product name "PPF-100T") was laminated on the HC-attached TAC film side of the obtained pressure-sensitive adhesive layer-attached optical film was used as the workpiece for profile processing. More specifically, the stack of laminates was stacked to a height of 10 mm, and the stack was fixed with a clamp. A through hole was drilled from the surface protective film side using an end mill with a blade diameter of 2.0 mm, and the hole was cut to a diameter of 2.5 mm (processed into a shape corresponding to the center of the bottom row in Figure 2). The cutting was performed at a blade rotation speed of 2500 rpm and a feed rate of 50 mm / min. The pressure-sensitive adhesive layer used to prepare the pressure-sensitive adhesive layer-attached optical film was evaluated in the above items (1) and (2). The pressure-sensitive adhesive layer-attached optical film before the profile processing was evaluated in the above item (3). The profile-processed pressure-sensitive adhesive layer-attached polarizing plate was evaluated in the above items (4) to (6). The results are shown in Table 1.

[0102] <Examples 2 to 6 and Examples 9 to 13> Deformed pressure-sensitive adhesive layer-attached optical films were produced in the same manner as in Example 1, except that the composition of the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer and the thickness of the pressure-sensitive adhesive layer were changed as shown in Table 1. The pressure-sensitive adhesive layer used in producing the pressure-sensitive adhesive layer-attached optical film, the pressure-sensitive adhesive layer-attached optical film having a separator, and the deformed pressure-sensitive adhesive layer-attached polarizing plate were subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[0103] Example 7 A pressure-sensitive adhesive layer-attached optical film subjected to profile processing was produced in the same manner as in Example 6, except that the separator was replaced once before profile processing. The pressure-sensitive adhesive layer used in producing the pressure-sensitive adhesive layer-attached optical film, the pressure-sensitive adhesive layer-attached optical film having a separator, and the pressure-sensitive adhesive layer-attached polarizing plate subjected to profile processing were subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[0104] Example 8 Except for replacing the separator twice, a pressure-sensitive adhesive layer-attached optical film subjected to profile processing was produced in the same manner as in Example 6. The pressure-sensitive adhesive layer used in producing the pressure-sensitive adhesive layer-attached optical film, the pressure-sensitive adhesive layer-attached optical film having a separator, and the pressure-sensitive adhesive layer-attached polarizing plate subjected to profile processing were subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[0105] Examples 14 and 15 (Preparation of Pressure-Sensitive Adhesive Composition) A mixture was prepared by blending 100 parts of the acrylic polymer (monomer partial polymer) A3 obtained in Production Example 3 with 10 parts of the (meth)acrylic oligomer B2 obtained in Production Example 7, 0.1 parts of a multifunctional monomer (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-HD-N", 1,6-hexanediol diacrylate) as a crosslinking agent, and 0.2 parts of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-403"). Next, the mixture was applied to the surface of a PET film (thickness 38 μm) serving as a base film (separator), and then another PET film was placed on top of the mixture coating, and the coating was sandwiched between the pair of PET films. Next, an illuminance of 4 mW / cm was applied. 2 and light intensity 1200mJ / cm 2The coating film was cured by irradiating it with ultraviolet light under the irradiation conditions described above, thereby forming pressure-sensitive adhesive layers (25 μm and 50 μm) with the thicknesses shown in Table 1. After the pressure-sensitive adhesive layer was formed, the additional PET film was peeled off to expose the pressure-sensitive adhesive layer, and a pressure-sensitive adhesive layer-attached optical film that had been contoured was produced in the same manner as in Example 1. The pressure-sensitive adhesive layer used to produce the pressure-sensitive adhesive layer-attached optical film, the pressure-sensitive adhesive layer-attached optical film having a separator, and the pressure-sensitive adhesive layer-attached polarizing plate that had been contoured were subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[0106] <Examples 16 to 19 and Comparative Example 1> Deformed pressure-sensitive adhesive layer-attached optical films were produced in the same manner as in Example 1, except that the composition of the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer and the thickness of the pressure-sensitive adhesive layer were changed as shown in Table 1. The pressure-sensitive adhesive layer used in producing the pressure-sensitive adhesive layer-attached optical film, the pressure-sensitive adhesive layer-attached optical film having a separator, and the deformed pressure-sensitive adhesive layer-attached polarizing plate were subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[0107] Example 20 A profile-processed pressure-sensitive adhesive layer-attached optical film was produced in the same manner as in Example 19, except that the separator was replaced once. The pressure-sensitive adhesive layer used in producing the pressure-sensitive adhesive layer-attached optical film, the pressure-sensitive adhesive layer-attached optical film having a separator, and the profile-processed pressure-sensitive adhesive layer-attached polarizing plate were subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[0108] <Example 21> (Preparation of polarizing plate) A long roll of 30 μm-thick polyvinyl alcohol film (manufactured by Kuraray, product name "PE3000") was uniaxially stretched in the longitudinal direction by a roll stretching machine to 5.9 times its original size while simultaneously undergoing swelling, dyeing, crosslinking, and washing treatments, and finally drying treatment to produce a 12 μm-thick polarizer. Specifically, the film was stretched 2.2 times while being swelled in pure water at 20°C. Then, the film was stretched 1.4 times while being dyed in a 30°C aqueous solution containing iodine and potassium iodide in a weight ratio of 1:7, with the iodine concentration adjusted so that the resulting polarizing film would have a transmittance of 45.0%. The crosslinking process was a two-stage process. In the first stage, the film was stretched 1.2 times while being treated in a 40°C aqueous solution containing boric acid and potassium iodide. The boric acid content of the aqueous solution used in the first stage was 5.0 wt % and the potassium iodide content was 3.0 wt %. In the second stage, the film was stretched 1.6 times while being treated in a 65°C aqueous solution containing boric acid and potassium iodide. The boric acid content of the aqueous solution used in the second stage was 4.3 wt % and the potassium iodide content was 5.0 wt %. The cleaning treatment was carried out with an aqueous potassium iodide solution at 20° C. The potassium iodide content of the aqueous solution used for the cleaning treatment was 2.6 wt %. Finally, the film was dried at 70° C. for 5 minutes to obtain a polarizer. A TAC film manufactured by Konica Minolta, Inc. (product name: KC2UA, thickness: 25 μm) and an HC-TAC film (thickness: 32 μm) having an HC layer on one side of the TAC film were bonded to both sides of the obtained polarizer via a polyvinyl alcohol-based adhesive, thereby obtaining polarizing plate 1 in which protective films were bonded to both sides of the polarizer.

[0109] (Preparation of Retardation Layer A) A liquid crystal composition (coating liquid) was prepared by dissolving 10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF, product name "Paliocolor LC242", represented by the following formula) and 3 g of a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by Ciba Specialty Chemicals, product name "Irgacure 907") in 40 g of toluene. [ka] The surface of a polyethylene terephthalate (PET) film (38 μm thick) was rubbed with a rubbing cloth to perform an alignment treatment. The alignment treatment conditions were: number of rubbings (number of rubbing rolls) 1, rubbing roll radius r 76.89 mm, rubbing roll rotation speed nr 1500 rpm, and film transport speed v 83 mm / sec.

[0110] The orientation direction was set to be -75° from the viewing side with respect to the absorption axis direction of the polarizer when attached to the polarizing plate. The above coating liquid was applied to this orientation-treated surface using a bar coater, and the liquid crystal compound was aligned by heating and drying at 90°C for 2 minutes. The liquid crystal layer thus formed was irradiated with 1 mJ / cm using a metal halide lamp. 2 The liquid crystal layer was cured by irradiating the PET film with light, thereby forming a retardation layer A on the PET film. The retardation layer A had a thickness of 2 μm and an in-plane retardation Re of 270 nm. Furthermore, the retardation layer A had a refractive index profile of nx>ny=nz.

[0111] (Preparation of Retardation Layer B) The surface of a polyethylene terephthalate (PET) film (38 μm thick) was rubbed with a rubbing cloth to perform an alignment treatment. The alignment direction was set to a -15° angle from the viewing side relative to the absorption axis of the polarizer when attached to a polarizing plate. The same liquid crystal coating solution as above was applied to this alignment-treated surface, and the liquid crystal was aligned and cured in the same manner as above to form a retardation layer B on the PET film. The retardation layer B had a thickness of 1.2 μm and an in-plane retardation Re of 140 nm. Furthermore, the retardation layer B had a refractive index distribution of nx > ny = nz.

[0112] (Preparation of polarizing plate with retardation layer) The TAC film surface of the polarizing plate and the retardation layer A were bonded together via an ultraviolet-curing adhesive so that the angle between the absorption axis of the polarizing plate and the slow axis of the retardation layer A was 75°. Next, the retardation layer A and the retardation layer B were bonded together via the same adhesive (thickness: 5 μm) as in Example 16 so that the angle between the absorption axis of the polarizing plate and the slow axis of the retardation layer B was 15°, thereby obtaining a polarizing plate with a retardation layer. Furthermore, adhesive layers similar to those in Examples 1 to 20 and Comparative Example 1 were formed on the outer side of the retardation layer B. The obtained polarizing plates with a retardation layer were subjected to profile processing in the same manner as in Example 1 and subjected to evaluation in the same manner as in Example 1. As a result, it was confirmed that, even in the polarizing plates with a retardation layer, those using adhesive layers corresponding to Examples 1 to 20 had good adhesive chipping and durability, while those using an adhesive layer corresponding to Comparative Example 1 had significant adhesive chipping.

[0113] [Table 1]

[0114] The abbreviations in Table 1 are as follows: The amount of each component in Table 1 is the number of parts per 100 parts of polymer. BA: butyl acrylate MMA: Methyl methacrylate MA: methyl acrylate AA: acrylic acid HBA: 4-hydroxybutyl acrylate HEA: 2-hydroxyethyl acrylate 2EHA: 2-ethylhexyl acrylate NVP: N-vinylpyrrolidone DCPM: dicyclopentanyl methacrylate ACMO: N-acryloylmorpholine D110N: Trimethylolpropane / xylylene diisocyanate adduct (manufactured by Tosoh Corporation, product name "Takenate D110N") C / L: Trimethylolpropane / tolylene diisocyanate adduct (manufactured by Tosoh Corporation, product name "Coronate L") Peroxide: peroxide crosslinking agent (manufactured by NOF Corporation, trade name "Niper BMT") A-HD-N: 1,6-hexaylenediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-HD-N") Si-cup agent: Epoxy group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-403") Antioxidant: pentaerythritol tetrakis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate) (manufactured by BASF, trade name "Irganox 1010")

[0115] <Evaluation> As is clear from Table 1, according to the examples of the present invention, adhesive chipping was significantly suppressed in the contoured areas, and an optical film with a pressure-sensitive adhesive layer was actually obtained in which peeling under high-temperature and high-humidity environments was suppressed. In Comparative Example 1, in which the creep value of the pressure-sensitive adhesive layer was large, the amount of adhesive chipping was large. Furthermore, in optical films with a pressure-sensitive adhesive layer having a separator, the amount of adhesive chipping was large when the peel strength of the separator was small (for example, comparison between Examples 6 and 8 and comparison between Examples 19 and 20). [Industrial Applicability]

[0116] The pressure-sensitive adhesive layer-attached optical film of the present invention can be suitably used in image display devices, and in particular, can be suitably used in image display devices having irregularly shaped parts, such as automobile instrument panels, smartphones, tablet PCs, or smart watches.

Claims

1. An optical film with a pressure-sensitive adhesive layer, comprising an optical film and a pressure-sensitive adhesive layer on one surface of the optical film, The pressure-sensitive adhesive layer-attached optical film has an irregular shape other than a rectangle, the pressure-sensitive adhesive layer has a creep value of 5 μm to 50 μm when a load of 500 gf is applied at 85°C and a swelling degree of 12 to 35 times; the amount of glue chipping of the pressure-sensitive adhesive layer in the irregular shape is 80 μm or less, the pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer obtained by radiation polymerization; Optical film with adhesive layer: Here, the swelling degree is determined by immersing the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer in ethyl acetate for 6 days and calculating (weight after immersion / dry weight after immersion); The amount of adhesive loss is determined by observing the cross section of the pressure-sensitive adhesive layer in the modified pressure-sensitive adhesive layer-attached optical film with an optical microscope, and is the length of the part where the pressure-sensitive adhesive layer is most missing from the outer edge inward in the planar direction.

2. An optical film with an adhesive layer as described in claim 1, wherein the (meth)acrylic polymer contains an amide group-containing monomer as a monomer component.

3. An optical film with an adhesive layer as described in claim 1 or 2, wherein the thickness of the adhesive layer is 2 μm to 20 μm.

4. The optical film with a pressure-sensitive adhesive layer according to claim 1, wherein the pressure-sensitive adhesive layer has a storage modulus at 85° C. of 1.0×10 4 Pa ​​to 1.0×10 6 Pa.

5. An optical film with an adhesive layer described in any one of claims 1 to 4, wherein the gel fraction of the adhesive layer is 55% to 95%.

6. An optical film with an adhesive layer described in any one of claims 1 to 5, wherein the optical film includes a polarizer.

7. An optical film with an adhesive layer as described in claim 6, wherein the optical film further comprises a retardation layer.

8. An image display device comprising an optical film with an adhesive layer described in any one of claims 1 to 7.

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