JP7715744B2 - Optical film with pressure-sensitive adhesive layer and image display device including said optical film with pressure-sensitive adhesive layer - Google Patents

Description

The present invention relates to an optical film with a pressure-sensitive adhesive layer and an image display device including the optical film with a pressure-sensitive adhesive layer.

Optical films are widely used in image display devices such as mobile phones and notebook personal computers to display images and/or improve the performance of those images. Optical films are typically provided with a pressure-sensitive adhesive layer to form pressure-sensitive adhesive-coated 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 (contiguous shapes: for example, the formation of notches and/or through holes). However, there is a problem in that the contoured portions of pressure-sensitive adhesive-coated optical films are prone to adhesive chipping (a phenomenon in which the edges of the pressure-sensitive adhesive layer are chipped). Furthermore, the pressure-sensitive adhesive layer is susceptible to peeling in high-temperature, high-humidity environments.

JP 2017-090896 A

The present invention was made to solve the above-mentioned problems of the prior art, and its main objective is to provide an optical film with a pressure-sensitive adhesive layer that significantly reduces glue chipping in contoured areas and significantly reduces peeling in high-temperature, high-humidity environments.

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-attached optical film has an irregular shape other than rectangular, and the pressure-sensitive adhesive layer has 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.

According to an embodiment of the present invention, in an optical film with a pressure-sensitive adhesive layer having a non-rectangular irregular shape (irregularly shaped portion), by setting the creep value of the pressure-sensitive adhesive layer at 85°C within a predetermined range, it is possible to realize an optical film with a pressure-sensitive 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.

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. 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. 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. 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.

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 may differ from the actual ones.

A. Overview of the Pressure-Sensitive Adhesive Layer-Attached Optical Film The 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 a deformed optical film whose entire shape (i.e., the outer edge defining the planar shape of the film) is other than rectangular, but also a rectangular optical film whose deformed portion is formed in a portion spaced inward from the outer edge. While such deformed portions are prone to glue chipping, an embodiment of the present invention significantly reduces such glue chipping. Examples of irregular shapes (irregularly shaped processed portions) include through holes and machined portions that become recesses in plan view, as shown in Figures 1 and 2 . Typical examples of recesses include a boat-like shape, a V-shaped notch, and a U-shaped notch. Another example of irregular shapes (irregularly shaped processed portions) is a shape corresponding to an automobile meter panel, as shown in Figures 3 and 4 . This shape includes a portion whose outer edge is formed in an arc shape that follows the rotation direction of the meter needle and whose outer edge forms a V-shape (including a curved shape) that convex inward in the planar direction. Needless to say, the shape of the irregular shapes (irregularly shaped processed portions) 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, in addition to 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-holes may be formed in the approximate center of the longitudinal end of the rectangular optical film, at a predetermined position of the longitudinal end, or at a corner of the optical film, as shown in FIG. 2; or, although not shown, at the lateral end of the rectangular optical film; or, as shown in FIG. 3 or 4, at the center of the irregular optical film. Furthermore, the shapes shown in the illustrations may be appropriately combined depending on the purpose. For example, through-holes may be formed at any position in the irregular optical film of FIG. 1; or V-notches and/or U-notches may be formed at any appropriate position on the outer edge of the irregular optical film of FIG. 3 or 4. Such irregular optical films may be suitably used in image display devices such as automobile instrument panels, smartphones, tablet PCs, and smartwatches.

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 that significantly suppresses glue chipping in contoured areas and significantly suppresses peeling in high-temperature, high-humidity environments. The configuration of the pressure-sensitive adhesive layer will be described in detail in Section C below.

The amount of glue chipping in the adhesive layer of an adhesive-layered optical film (particularly the adhesive layer in the profiled area) 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 can be, for example, 5 μm. In this specification, "amount of glue chipping" refers to the maximum amount of glue chipping inward from the outer edge of the optical film (including the outer edge of the through holes) in the planar direction.

In one embodiment, a separator is temporarily and removably attached to the surface of the pressure-sensitive adhesive layer opposite the optical film. Examples of separators 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.

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 adhesive layer (particularly the adhesive layer in the profiled area) can be reduced. If the separator peel strength exceeds 0.5 N/50 mm, the separator's releasability will decrease, potentially resulting in process defects.

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 (e.g., anti-reflection circular polarizing plates, polarizing plates with a conductive layer for touch panels) in which optical films composed of these single layers and/or optical films composed of laminates are appropriately laminated depending on the purpose. Hereinafter, polarizing plates and circular polarizing plates will be briefly described as typical examples of optical films.

B-1. Polarizing Plate A polarizing plate typically has a polarizer and a protective layer provided on one or both sides of the polarizer.

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. The resin film is typically a polyvinyl alcohol-based resin (hereinafter referred to as a "PVA-based resin") film. The resin film may be a single-layer resin film or a laminate of two or more layers.

A specific example of a polarizer composed of a single-layer resin film is a PVA-based resin film that has been dyed with iodine and stretched (typically, uniaxially stretched). The iodine dyeing is performed, for example, by immersing the PVA-based film in an aqueous iodine solution. The stretching ratio for the uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing process or while dyeing. Alternatively, the film may be dyed after stretching. If necessary, the PVA-based resin film may be subjected to swelling, crosslinking, washing, drying, or other treatments. For example, immersing the PVA-based resin film in water and rinsing it before dyeing not only cleans off dirt and antiblocking agents from the PVA-based film surface, but also swells the PVA-based resin film to prevent uneven dyeing.

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 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 it to form a PVA-based resin layer on the resin substrate to obtain 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 to stretch 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 resulting 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 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 polarizer manufacturing methods are described, for example, in JP-A-2012-73580 and Japanese Patent No. 6,470,455. The entire disclosures of these publications are incorporated herein by reference.

The thickness of the polarizer is preferably 25 μm or less, more preferably 1 μm to 12 μm, even more preferably 3 μm to 12 μm, and particularly preferably 3 μm to 8 μm. A polarizer thickness within this range effectively suppresses curling when heated and provides good appearance durability when heated.

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%, and 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.

B-1-2. Protective Layer The protective layer is formed of any appropriate 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 silicone resins. 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 a substituted or unsubstituted imide group in its side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in its side chain, 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.

The protective layer on the side opposite the adhesive layer (outer protective layer) may be subjected to surface treatments such as hard coating, anti-reflection treatment, anti-sticking treatment, and anti-glare treatment, as needed.

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, brightness enhancement film, diffusion film, etc.

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. If a surface treatment has been applied, the thickness of the protective layer includes the thickness of the surface treatment layer.

B-2. Circularly Polarizing Plate A circularly polarizing plate typically includes a polarizer and a retardation layer. In practice, the polarizer may be included in the circularly polarizing plate as a polarizing plate having a protective layer on one or both sides. The retardation layer is typically disposed between the polarizing plate and the pressure-sensitive adhesive layer. The polarizer and the polarizing plate are as described above in Section B-1.

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

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 with the wavelength of the measurement light, positive wavelength dispersion characteristics in which the retardation value decreases with the wavelength of the measurement light, or flat wavelength dispersion characteristics in which the retardation value changes little with the wavelength of the measurement light. In one embodiment, the retardation layer exhibits reverse dispersion wavelength characteristics. In this case, the Re(450)/Re(550) of the retardation layer is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less.

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 this 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°.

The retardation layer can be made of any suitable material as long as it satisfies the above-mentioned characteristics. For example, the retardation layer can be a resin film (typically a stretched film) or a liquid crystal compound alignment layer (liquid crystal alignment layer). Typical examples of resins that make up 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 can be used alone or in combination (e.g., blends or copolymers). When the retardation layer is made of a resin film that exhibits reverse dispersion wavelength characteristics, polycarbonate-based resins or polyester carbonate-based resins (hereinafter sometimes simply referred to as polycarbonate-based resins) can be preferably used. Details of polycarbonate resins suitable for use in retardation layers and methods for forming retardation layers are described, for example, in JP-A Nos. 2014-10291, 2014-26266, 2015-212816, 2015-212817, and 2015-212818; specific examples of liquid crystal compounds and details of methods for forming alignment-solidified layers are described, for example, in JP-A No. 2006-163343. The disclosures of these publications are incorporated herein by reference.

C. Pressure-Sensitive Adhesive Layer C-1. Characteristics of the Pressure-Sensitive 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, 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 shaped 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 pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer (for example, the type (polarity, Tg, softness), and molecular weight of the base polymer), 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 1 second and 3600 seconds after applying the load is measured and designated _Cr1 and _Cr3600 , respectively. ΔCr, calculated from _Cr1 and _Cr3600 using the following formula, is designated the creep value.
ΔCr=Cr ₃₆₀₀ - Cr ₁

The pressure-sensitive adhesive layer has a storage modulus at 85°C of preferably 1.0 x 10 ⁴ Pa or more, preferably 2.0 x 10 ⁴ Pa or more, more preferably 5.0 x 10 ⁴ Pa or more, and even more preferably 1.0 x 10 ⁵ Pa or more. If the storage modulus is within this range, the desired creep value can be easily achieved. On the other hand, the storage modulus is, for example, 3.0 x 10 ⁶ Pa or less. If 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.

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

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 calculated by multiplying the weight of the crosslinked PSA by (dry weight after immersion/dry weight before immersion) x 100 after immersion in a specific solvent (e.g., ethyl acetate) for six days and then drying. 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 measured, for example, by gel permeation chromatography (GPC) and calculated in polystyrene equivalent terms.

The swelling degree of the adhesive layer is preferably 35 times or less, more preferably 10 to 30 times, even more preferably 11 to 28 times, and especially preferably 12 to 20 times. A swelling degree within this range significantly reduces glue chipping in contoured areas. The swelling degree is determined by immersing the crosslinked adhesive in a specified solvent (e.g., ethyl acetate) for six days and calculating (weight after immersion/dry weight after immersion).

The storage modulus, gel fraction, and degree of swelling of the adhesive layer can be controlled by adjusting the composition of the adhesive that makes up the adhesive layer (e.g., the type of base polymer (polarity, Tg, softness), and molecular weight), 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, etc. can be appropriately set.

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 especially preferably 5 μm to 15 μm. If the thickness of the adhesive layer is within this range, it can significantly reduce glue chipping in irregularly shaped areas due to the synergistic effect with the effect of controlling the creep value.

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 the 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.

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.

The alkyl (meth)acrylate that constitutes 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. 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.

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

The carboxyl group-containing monomer (a1) is a compound that contains a carboxyl group in its structure and a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group. Examples of carboxyl group-containing monomers 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 improved adhesive properties of the adhesive layer.

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

The hydroxyl group-containing monomer (a2) is a compound that contains a hydroxyl group in its structure and a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group. Examples of hydroxyl group-containing monomers 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, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred, with 4-hydroxybutyl (meth)acrylate being more preferred, from the viewpoint of improving the durability of the pressure-sensitive adhesive layer.

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

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 with 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 with a glass transition temperature of 0°C or higher include alkyl (meth)acrylate monomers and (meth)acrylic acid. Monomer (a3) is preferably a monomer having an unsaturated carbon-carbon double bond that results in a homopolymer with 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 with a glass transition temperature of 40°C or higher.

The proportion of monomer (a3) contained in (meth)acrylic polymer (A) is not particularly limited. The content is typically 0.1% to 40% by weight, and more preferably 1% to 30% by weight. Note that the content refers to the total content when two or more types of monomer (a3) are used in combination.

Examples of 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 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 can be used alone or in combination.

When the pressure-sensitive adhesive composition contains a crosslinking agent, as 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 intermolecular crosslinking agents and are therefore preferably used to improve the cohesiveness and heat resistance of the resulting pressure-sensitive adhesive layer. Furthermore, carboxyl group-containing monomers are preferred because they combine durability and reworkability, while hydroxyl group-containing monomers are preferred because they improve reworkability.

Another copolymerizable monomer (a4) may also be used as a monomer component. The other copolymerizable monomer (a4) has a polymerizable functional group with an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group. By using the other copolymerizable monomer (a4), the adhesive properties and heat resistance of the PSA layer can be improved. The other copolymerizable monomer (a4) can be used alone or in combination.

The adhesion 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 amino group-containing monomers include N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate. Examples of amide group-containing monomers include acrylamide 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 monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam.

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.

Other copolymerizable monomers (a4), in addition to those mentioned above, include, for example, (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 methyl glycidyl (meth)acrylate; sulfonic acid group-containing monomers such as sodium vinyl sulfonate. Examples of monomers that can be used include: monomers containing a phosphate group; (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.

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.

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.

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

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 amount of polymerization initiator and chain transfer agent used and the reaction conditions, and the type and amount used can be adjusted depending on the desired weight-average molecular weight.

Examples of polymerization initiators 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 initiators 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 peroxides with reducing agents, such as combinations of persulfates and sodium hydrogen sulfite, and combinations of peroxides and sodium ascorbate.

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

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. Chain transfer agents may be used alone or in combination of two or more. The total amount of chain transfer agent used is approximately 0.1 parts by weight or less per 100 parts by weight of the monomer components.

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.

Reactive emulsifiers include those incorporating radically polymerizable functional groups such as propenyl groups and allyl ether groups. Specific examples include Aqualon HS-10, HS-20, KH-10, BC-05, BC-10, and BC-20 (all manufactured by Dai-ichi 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, and more preferably 0.5 to 1 part by weight, per 100 parts by weight of the total amount of monomer components. Using an amount of emulsifier within this range ensures excellent polymerization stability and mechanical stability of the resulting adhesive layer.

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 rays. When radiation polymerization is performed using UV polymerization, a photopolymerization initiator can be added to the monomer components, which shortens the polymerization time. When radiation polymerization is performed using electron beams, it is not particularly necessary to add a photopolymerization initiator to the monomer components.

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

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. If 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.

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 contains a large amount of low-molecular-weight polymers. Even if the adhesive layer is formed so that the creep value is the same as above, 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 profile processing or peeling in high-temperature, high-humidity environments. Like the weight average molecular weight, the polydispersity (Mw/Mn) is measured by GPC (gel permeation chromatography) and calculated as a polystyrene equivalent.

C-4. Reactive Functional Group-Containing Silane Coupling Agent The PSA 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 acid anhydride groups 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 can be used alone or in combination.

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 a commercially available epoxy group-containing silane coupling agent is "KBM-403" manufactured by Shin-Etsu Chemical Co., Ltd.

Reactive functional group-containing silane coupling agents can also be used that contain multiple alkoxysilyl groups within the molecule (oligomeric silane coupling agents). 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 contain multiple alkoxysilyl groups, they can be effective in improving durability.

When a reactive functional group-containing silane coupling agent is blended into the pressure-sensitive adhesive composition, the amount of reactive functional group-containing silane coupling agent blended is typically 0.001 to 5 parts by weight per 100 parts by weight of the (meth)acrylic polymer (A).

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-based crosslinking agents, peroxide-based crosslinking agents, epoxy-based crosslinking agents, and imine-based 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. Preferred polyfunctional acrylates are 1,6-hexanediol diacrylate and dipentaerythritol hexa(meth)acrylate. The crosslinking agents may be used alone or in combination.

When the pressure-sensitive adhesive composition is solvent-based, the crosslinking agent is preferably an isocyanate-based crosslinking agent and/or a peroxide-based crosslinking agent, with isocyanate-based crosslinking agents being particularly preferred from the perspective of reducing adhesive chipping during processing, and using an isocyanate-based crosslinking agent in combination with a peroxide-based crosslinking agent is more preferred from the perspective of preventing peeling in high-temperature, high-humidity environments.

The isocyanate-based crosslinking agent can be, 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). For example, any suitable aliphatic polyisocyanate, alicyclic polyisocyanate, aromatic polyisocyanate, or the like that can be used in a urethanization reaction can be used.

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.

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.

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.

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

Commercially available isocyanate crosslinking agents include, for example, 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."

Preferred isocyanate-based crosslinking agents include aromatic polyisocyanates and their modified aromatic polyisocyanate compounds, and aliphatic polyisocyanates and their modified aliphatic polyisocyanate compounds. Aromatic polyisocyanate-based compounds are preferably used because they offer a good balance between crosslinking speed and pot life. Tolylene diisocyanate and its modified aromatic polyisocyanate compounds are particularly preferred.

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

Examples of 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-butyl peroxydicarbonate (1-minute half-life temperature: 92.4°C), t-butyl peroxyneodecanoate (1-minute half-life temperature: 103.5°C), t-hexyl peroxypivalate (1-minute half-life temperature: 109.1°C), t-butyl peroxypivalate (1-minute half-life temperature: 110.3°C), dilauroyl peroxy Examples of peroxybenzoates include tetramethylbutylperoxyisobutyrate (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 due to their particularly excellent crosslinking reaction efficiency.

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 given time, and the half-life time at any given temperature, are listed in manufacturer catalogs, for example, NOF Corporation's "Organic Peroxide Catalog, 9th Edition (May 2003)."

When a crosslinking agent is blended into the pressure-sensitive adhesive composition, the amount of crosslinking agent blended is typically 0.01 parts by weight or more and 15 parts by weight or less per 100 parts by weight of the (meth)acrylic polymer (A).

When an isocyanate-based crosslinking agent is blended into the pressure-sensitive adhesive composition, the amount of the isocyanate-based crosslinking agent blended is typically 0.01 parts by weight or more and 15 parts by weight or less per 100 parts by weight of the (meth)acrylic polymer.

When a peroxide is blended into the pressure-sensitive adhesive composition, the amount of peroxide blended is typically 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 processability, crosslinking stability, and other properties.

C-6. Other Components The PSA 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 a (meth)acrylic oligomer is blended into the PSA 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.

The pressure-sensitive adhesive composition may contain an ionic compound. Any appropriate ionic compound can 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 can 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).

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).

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. Therefore, an image display device including a pressure-sensitive adhesive layer-attached optical film is also included 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.

The present invention will be explained in more detail 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.

(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) x 100
(2) Swelling Degree The pressure-sensitive 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 degree (fold) = weight after immersion / dry weight after immersion (3) Separator peeling force The pressure-sensitive adhesive layer-attached optical films (before profile processing) used in the examples and comparative examples were cut into a size of 50 mm × 150 mm to prepare measurement samples. 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 separator peeling force 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. A 10 mm x 10 mm portion of the upper end of each test sample 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 displacement 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, and these values were designated Cr ₁ and Cr ₃₆₀₀ , respectively. The creep value was determined as ΔCr by the following formula using Cr ₁ and Cr ₃₆₀₀ .
ΔCr=Cr ₃₆₀₀ - Cr ₁
(5) Amount of glue chipping 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 most chipped from the outer edge inward in the planar direction was measured, and this length was taken as the amount of glue chipping (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 in the long-side direction. These test samples were then bonded 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 500 hours of 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 no practical problem.
×: Significant peeling at the edge, causing problems in practical use.

<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 with nitrogen, and the liquid temperature in the flask was maintained at around 55°C, allowing a polymerization reaction to occur for 8 hours to prepare a solution of acrylic polymer A1 having a weight average molecular weight (Mw) of 1,800,000 and Mw/Mn = 4.8.

<Production Example 2: Preparation of Acrylic Polymer A2>
A solution of acrylic polymer A2 having a Mw of 2,300,000 and a Mw/Mn of 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.

<Production Example 3: Preparation of acrylic polymer (monomer partial polymer) A3>
A four-neck flask equipped with a thermometer, a nitrogen gas inlet tube, a 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 photopolymerization initiators Omnirad 651 and Omnirad 184 were charged per 100 parts of this monomer mixture. Next, while rotating the spindle, nitrogen gas was introduced to replace the atmosphere inside the flask with nitrogen. Photopolymerization was then allowed to proceed by irradiating with ultraviolet light until the viscosity of the polymerization system measured by the viscometer reached approximately 15 Pa s, yielding an acrylic polymer A3 containing a partial polymer of the monomer groups. A Toki Sangyo BH-type viscometer was used, and the rotation speed of the spindle (rotor No. 5) was 10 rpm. The liquid temperature inside the flask was maintained at 30°C.

<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.

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

<Production Example 6: Preparation of acrylic oligomer B1>
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 95 parts of butyl acrylate, 2 parts of acrylic acid, and 3 parts of methyl acrylate. Furthermore, 0.1 parts of 2,2'-azobisisobutyronitrile as a polymerization initiator and 140 parts of toluene were charged to 100 parts of this monomer mixture. Nitrogen gas was introduced with gentle stirring to thoroughly replace the atmosphere with nitrogen. The liquid temperature in the flask was maintained at around 70°C, and a polymerization reaction was carried out for 8 hours to prepare a solution of acrylic oligomer B1. The Mw of the oligomer was 4,500.

<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 at 70°C for 1 hour under a nitrogen atmosphere. Next, 0.2 parts of AIBN was added as a thermal polymerization initiator, and the mixture was reacted at 70°C for 2 hours, and then the temperature was raised to 80°C and the mixture was reacted for 2 hours. Thereafter, the reaction solution was heated to 130°C, and the toluene, chain transfer agent, and unreacted monomers were dried and removed to obtain (meth)acrylic oligomer B2.

<Production Example 8: Preparation of polarizing plate>
(Preparation of HC-attached TAC film)
A resin solution (DIC Corporation, product name: Unidic 17-806, solids concentration: 80%) in which a UV-curable resin monomer or oligomer primarily composed of urethane acrylate was dissolved in butyl acetate was prepared. Five parts of a photopolymerization initiator (BASF Corporation, 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 to the solution in a ratio of 45:55 so that the solids concentration of the solution was 36%, to prepare 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) so that the thickness of the hard coat layer after curing was 7 μm, forming a coating film. The coating film was dried at 90°C for 1 minute and then irradiated with ultraviolet light from a high-pressure mercury lamp at an integrated light intensity of 300 mJ/ ^cm2 to harden the coating film and form a hard coat layer, thereby producing a TAC film with HC. The resulting TAC film with HC was subjected to a saponification treatment.

(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. Thereafter, the film was stretched to a total stretch ratio of 6 times while immersed in an aqueous solution containing 4% boric acid and 10% potassium iodide at 60°C for 0.5 minutes. 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 a polarizer with a thickness of 18 μm. The HC-attached TAC film obtained above was bonded to one side of the polarizer, and a saponified 40 μm thick TAC film (KC4CT, manufactured by Konica Minolta) was bonded to the other side with a polyvinyl alcohol-based adhesive, to produce a polarizing plate.

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 NOF 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.

(Preparation of Polarizing Plate with Pressure-Sensitive 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. At this time, 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 diameter was cut to 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.

<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.

Example 7
Except for replacing the separator once before the profile processing, a profile-processed pressure-sensitive adhesive layer-attached optical film 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 profile-processed pressure-sensitive adhesive layer-attached polarizing plate were subjected to evaluations in the same manner as in Example 1. The results are shown in Table 1.

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.

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 (1,6-hexanediol diacrylate, product name "A-HD-N" manufactured by Shin-Nakamura Chemical Co., Ltd.) as a crosslinking agent, and 0.2 parts of a silane coupling agent (product name "KBM-403" manufactured by Shin-Etsu Chemical Co., Ltd.). The mixture was then applied to the surface of a PET film (38 μm thick) serving as a substrate film (separator), and another PET film was placed on top of the mixture coating, sandwiching the coating between the pair of PET films. The coating was then cured by irradiating it with ultraviolet light at an illuminance of ⁴ mW/ ^cm² and a light intensity of 1200 mJ/cm², 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 subjected to profile processing was produced in the same manner as in Example 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 pressure-sensitive adhesive layer-attached polarizing plate subjected to profile processing were subjected to evaluations in the same manner as in Example 1. The results are shown in Table 1.

<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.

Example 20
Except for replacing the separator once, a pressure-sensitive adhesive layer-attached optical film subjected to profile processing was produced in the same manner as in Example 19. 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.

Example 21
(Preparation of polarizing plate)
A long roll of a polyvinyl alcohol film (manufactured by Kuraray, product name "PE3000") having a thickness of 30 μm was uniaxially stretched in the longitudinal direction by a roll stretching machine so as to be 5.9 times its original size in the longitudinal direction, while simultaneously undergoing swelling, dyeing, crosslinking, and washing treatments, and finally undergoing a drying treatment, thereby producing a polarizer having a thickness of 12 μm.
Specifically, the film was stretched 2.2 times while being treated with pure water at 20°C for the swelling treatment. Then, the film was stretched 1.4 times while being treated in an aqueous solution at 30°C containing iodine and potassium iodide at a weight ratio of 1:7, with the iodine concentration adjusted so that the resulting polarizing film would have a transmittance of 45.0%. Furthermore, the crosslinking treatment was a two-stage process. In the first stage, the film was stretched 1.2 times while being treated in an aqueous solution containing boric acid and potassium iodide at 40°C. 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 an aqueous solution containing boric acid and potassium iodide at 65°C. 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 (product name: KC2UA, thickness: 25 μm) manufactured by Konica Minolta, Inc. 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, respectively, to obtain a polarizing plate 1 in which protective films were bonded to both sides of the polarizer.

(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.
The surface of a polyethylene terephthalate (PET) film (thickness: 38 μm) was subjected to an alignment treatment by rubbing with a rubbing cloth under the following conditions: 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.

The orientation direction was set to -75° relative to the absorption axis of the polarizer when attached to the polarizing plate, as viewed from the viewing side. The above-mentioned 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 light of 1 mJ/ ^cm² using a metal halide lamp, and the liquid crystal layer was cured to form 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 distribution of nx > ny = nz.

(Preparation of Retardation Layer B)
The surface of a polyethylene terephthalate (PET) film (thickness: 38 μm) was rubbed with a rubbing cloth and subjected to an alignment treatment. The direction of the alignment treatment was set to a -15° angle from the viewing side with respect to the direction of 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.

(Preparation of polarizing plate with retardation layer)
The TAC film surface of the polarizing plate and the retardation layer A were bonded via a UV-curable 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 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 processed to a profile in the same manner as in Example 1 and subjected to the same evaluation 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.

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, trade name "Takenate D110N")
C/L: Trimethylolpropane/tolylene diisocyanate adduct (manufactured by Tosoh Corporation, trade 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., trade 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")

<Evaluation>
As is clear from Table 1, according to the examples of the present invention, adhesive chipping was significantly suppressed in the contoured portion, 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 force of the separator was small (for example, comparison between Examples 6 and 8 and comparison between Examples 19 and 20).

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 (7)

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.
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 . The optical film with a pressure-sensitive adhesive layer according to claim 1, wherein the pressure-sensitive adhesive layer has a thickness of 2 μm to 20 μm. 3. The pressure-sensitive adhesive layer-attached optical film 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. The optical film with a pressure-sensitive adhesive layer according to any one of claims 1 to 3, wherein the gel fraction of the pressure-sensitive adhesive layer is 55% to 95%. The pressure-sensitive adhesive layer-attached optical film according to claim 1 , wherein the optical film comprises a polarizer. The pressure-sensitive adhesive layer-attached optical film according to claim 5 , wherein the optical film further comprises a retardation layer. An image display device comprising the pressure-sensitive adhesive layer-attached optical film according to claim 1 .