Active energy ray-curable adhesive sheet, adhesive sheet, laminate for image display device, image display device, and method for producing laminate for constituting image display device

Abstract

Proposed is a novel active energy ray-curable adhesive sheet capable of achieving excellent flowability and also capable of achieving foaming reliability that, after being layered on an adherend and being cured, does not undergo foaming even when the adherend undergoes dimensional change. The active energy ray-curable adhesive sheet comprises an adhesive layer formed from an adhesive resin composition containing a (meth)acrylic polymer (A), wherein, when the thickness is from 0.8 to 1.5 mm, the creep strain, before curing, after 1200 seconds at 50°C is 150% or greater to less than 1500%, and the creep strain, after curing according to the following curing condition, after 180 seconds at 80°C is 10% or greater.　Curing condition: Curing by irradiation with 365-nm UV light in an accumulated light amount within the range from 3000 to 4000 mJ / cm2.

Description

[Technical Field]

[0001] The present invention relates to an active energy ray-curable pressure-sensitive adhesive sheet having the property of being cured by active energy rays, a laminate for an image display device using the same, an image display device, and a method for producing a laminate for constituting an image display device. [Background technology]

[0002] In recent years, in order to improve the visibility of image display devices, the gap between an image display panel such as a liquid crystal display (LCD), plasma display (PDP), or electroluminescence display (ELD) and a protective panel or touch panel member placed on the front side (viewing side) of the image display panel has been filled with an adhesive sheet, liquid adhesive, or the like to suppress reflection of incident light and outgoing light from the displayed image at the air layer interface.

[0003] As a method for filling a pressure-sensitive adhesive into a gap between components of such an image display device, for example, Patent Document 1 discloses a method in which a liquid adhesive resin composition containing an ultraviolet-curable resin is filled into the gap, and then the composition is cured by irradiating the composition with ultraviolet light.

[0004] Also known is a method of filling gaps between components of an image display device with a pressure-sensitive adhesive sheet. For example, Patent Document 2 discloses a method for manufacturing a laminate for constituting an image display device, which has a configuration in which components of an image display device are laminated on at least one side of a transparent double-sided pressure-sensitive adhesive sheet, in which a pressure-sensitive adhesive sheet that has been primarily cross-linked by ultraviolet light is attached to the components of the image display device, and then the pressure-sensitive adhesive sheet is irradiated with ultraviolet light through the components of the image display device for secondary curing.

[0005] Patent Document 3 discloses a method for adhering components of an image display device using an adhesive sheet containing an adhesive resin composition containing an acrylic copolymer made of a graft copolymer having a macromonomer as a branch component, a crosslinking agent, and a photopolymerization initiator, and then irradiating the sheet with active energy rays through the components of the image display device to crosslink the adhesive resin composition, thereby adhering the components of the image display device.

[0006] Patent Document 4 discloses a photocurable adhesive sheet used to bond a resin member (X) having a light transmittance of 10% or less at a wavelength of 365 nm and a light transmittance of 60% or more at a wavelength of 405 nm, the photocurable adhesive sheet being characterized by having an adhesive layer (Y) having all of the following properties (1) to (3): (1) The gel fraction (referred to as "pre-light irradiation gel fraction X1") is in the range of 0 to 60%. (2) The light transmittance at a wavelength of 390 nm is 89% or less, and the light transmittance at a wavelength of 410 nm is 80% or more. (3) It has photocuring properties, meaning it hardens when exposed to light with a wavelength of 405 nm. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2010 / 027041 [Patent Document 2] Patent No. 4971529 [Patent Document 3] International Publication No. 2015 / 137178 [Patent Document 4] Japanese Patent Application Publication No. 2019-210445 Summary of the Invention [Problem to be solved by the invention]

[0008] In recent years, there has been a trend in designs for image display devices such as mobile phones to use almost the entire area of ​​the image display panel as a display, and as a result, cameras have come to be placed within the display area. Methods for placing a camera within a display include drilling a hole in the image display panel itself and inserting the camera lens directly below the surface protection panel, and placing the camera below the image display panel. In the latter method, the camera must be placed through the image display panel, so in order to ensure light transmission to the camera lens, a hole is formed in a functional layer, such as a polarizing film or a reflective film, laminated on the surface of the image display panel, in accordance with the position and size of the camera.

[0009] An adhesive sheet for bonding together components of an image display device having such holes is required to have a property (fluidity) that allows the adhesive to flow into the holes and fill every corner. Furthermore, since stress tends to concentrate near holes in components of the image display device due to dimensional changes in the components, there is a risk that the adhesive filled inside the holes will peel off or foam, resulting in a decrease in light transmittance. Therefore, the adhesive constituting the adhesive sheet is required to have the property of not foaming even if the adherend changes in dimension after being laminated and cured on the adherend (foaming resistance reliability).

[0010] The present invention provides a new active energy ray-curable adhesive sheet that can exhibit excellent fluidity and, further, can exhibit foaming resistance reliability, i.e., does not foam even if the adherend undergoes dimensional changes after being laminated and cured on the adherend; an adhesive sheet that has the property of being cured by active energy rays; a laminate for an image display device that uses the same; and a method for producing the same. [Means for solving the problem]

[0011] The present invention provides an active energy ray-curable adhesive sheet that includes an adhesive layer formed from an adhesive resin composition containing a (meth)acrylic polymer (A), and that, when made 0.8 to 1.5 mm thick, exhibits a creep strain of 150% or more and less than 1500% after 1200 seconds at 50°C before curing, and a creep strain of 10% or more after 180 seconds at 80°C after curing under the following curing conditions. Curing conditions: 3000-4000mJ / cm with 365nm ultraviolet light 2 The resin is cured by irradiating it with an integrated amount of light within the range.

[0012] The present invention also provides a laminate for constituting an image display device, which is configured by laminating two image display device components via a pressure-sensitive adhesive sheet having a thickness of 0.8 to 1.5 mm, and which has a creep strain of 10% or more after curing at 80°C for 180 seconds under the following curing conditions, and at least one of the image display device components has a depth (mm) / base area (mm) ratio on the contact surface with the pressure-sensitive adhesive sheet. 2 ) is 1.0 × 10 -5 ~3.0×10 -1 The present invention proposes a laminate for use in an image display device, which has a bottomed hole of the above formula (1), and the bottomed hole is filled with the adhesive sheet after curing in a state where no voids with a diameter of 1 mm or more exist. Curing conditions: 3000-4000mJ / cm with 365nm ultraviolet light 2 The resin is cured by irradiating it with an integrated amount of light within the range.

[0013] The present invention also provides a laminate for constituting an image display device, comprising two image display device constituent members laminated together via a pressure-sensitive adhesive sheet having a thickness of 0.8 to 1.5 mm, which has a creep strain of 10% or more after curing at 80°C for 180 seconds under the following curing conditions: At least one of the components of the image display device has a depth (mm) / base area (mm 2 ) is 1.0 × 10 -5 ~3.0×10 -1The present invention proposes a laminate for use in an image display device, which has a bottomed hole of the above formula (1), and the bottomed hole is filled with the adhesive sheet after curing in a state where no voids with a diameter of 1 mm or more exist. Curing conditions: 3000-4000mJ / cm with 365nm ultraviolet light 2 The resin is cured by irradiating it with an integrated amount of light within the range.

[0014] The present invention further provides a method for producing a laminate for constituting an image display device, which has a configuration in which two image display device constituent members are laminated via the above-mentioned cured active energy ray-curable adhesive sheet, the method comprising: The pressure-sensitive adhesive sheet is bonded to one surface of a first image display device component to form a bonded body, a surface to be bonded of a second image display device component having a bottomed hole on the surface to be bonded and a pressure-sensitive adhesive sheet of the bonded body are brought into face-to-face contact with each other under reduced pressure to form a laminate; a pressure-sensitive adhesive resin composition is allowed to flow into the bottomed hole of the second image display device component by subjecting the laminate to a heating and pressurizing treatment to hot-melt the pressure-sensitive adhesive sheet; We propose a method for manufacturing a laminate for constituting an image display device, characterized in that the adhesive sheet sandwiched between first and second image display components is irradiated with active energy rays to harden the adhesive sheet. [Effects of the Invention]

[0015] The active energy ray-curable adhesive sheet proposed by the present invention can be hot-melted by heating and pressurizing, thereby exhibiting excellent fluidity. Therefore, the hot-melted adhesive resin composition can be flowed into the pores of an adherend, filling every corner. Furthermore, by laminating the adhesive sheet between two adherends and curing it by irradiating with active energy rays, not only can the two adherends, particularly components of an image display device, be joined, but the adhesive filled in the pores will not foam even if the adherends change in size, demonstrating excellent foaming resistance reliability. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention will now be described based on embodiments, although the present invention is not limited to the embodiments described below.

[0017] <This adhesive sheet> An adhesive sheet according to one embodiment of the present invention (referred to as "the adhesive sheet") is an active energy ray-curable adhesive sheet having an adhesive layer (referred to as "the adhesive layer") formed from an adhesive resin composition (referred to as "the adhesive resin composition") containing a (meth)acrylic polymer (A).

[0018] The "active energy ray-curable adhesive sheet" means an adhesive sheet that has the property of being curable by active energy rays, in other words, an adhesive sheet that has active energy ray-curability and has room to be cured by active energy rays. The pressure-sensitive adhesive sheet may be cured to a state where there is still room for curing by active energy rays (also referred to as "pre-cured"), or may be one that has not yet been cured at all (referred to as "uncured") and can be cured by active energy rays. If the adhesive sheet is pre-cured or uncured, after the adhesive sheet is attached to the adherend, the adhesive sheet can be cured (also referred to as "full curing") with active energy rays, thereby increasing the cohesive strength and improving the adhesiveness.

[0019] The pressure-sensitive adhesive layer forming the pressure-sensitive adhesive sheet may be in a slightly crosslinked state, i.e., a state in which the gel fraction is greater than 0% and less than 40%, before being cured by active energy rays, or may be in an uncrosslinked state, i.e., a state in which the gel fraction is 0%. From the viewpoint of flowability into the bottomed holes in the adherend surface, an uncrosslinked state is preferable.

[0020] The present pressure-sensitive adhesive sheet may have a single layer structure consisting of the present pressure-sensitive adhesive layer, or may have a multi-layer structure consisting of two or more layers each including the present pressure-sensitive adhesive layer. When the present pressure-sensitive adhesive sheet has a multi-layer structure of two or more layers, it is preferable that at least the outermost layer or the innermost layer, or both, are layers corresponding to the present pressure-sensitive adhesive layer, although all layers may be layers corresponding to the present pressure-sensitive adhesive layer.

[0021] The thickness of the pressure-sensitive adhesive sheet is preferably 10 μm to 500 μm, more preferably 15 μm or more or 400 μm or less, and even more preferably 20 μm or more or 350 μm or less.

[0022] When the adhesive sheet has a multi-layer structure of two or more layers, it is preferable that the thickness of the layer corresponding to the adhesive layer accounts for 20 to 100% of the total thickness of the adhesive sheet, and more preferably 30% or more or 95% or less, and even more preferably 40% or more or 90% or less.

[0023] When the pressure-sensitive adhesive sheet has a thickness of 0.8 to 1.5 mm, it is preferable that the creep strain after 1200 seconds at 50° C. before curing is 150% or more and less than 1500%. In the present pressure-sensitive adhesive sheet, if the creep strain after 1200 seconds at 50°C is 150% or more, it is preferable because the pressure-sensitive adhesive resin can flow and fill uneven portions such as bottomed holes by heating. From this viewpoint, it is more preferable that it is 160% or more, and even more preferable that it is 180% or more, and even more preferable that it is 200% or more. On the other hand, if the creep strain after 1200 seconds at 50°C is less than 1500%, it is preferable from the viewpoint of excellent dimensional stability of the PSA sheet. From this viewpoint, it is more preferable that it is 1400% or less, of which 1300% or less, and of which 1200% or less is even more preferable. In the present pressure-sensitive adhesive sheet, the creep strain before curing can be adjusted to the above range preferably by adjusting the composition or molecular weight of the (meth)acrylic polymer (A) which is the main component resin, or by adjusting the type or amount of the reactive diluent (B), although this is not limitative.

[0024] When the pressure-sensitive adhesive sheet has a thickness of 0.8 to 1.5 mm, it is preferable that the creep strain after curing at 80° C. for 180 seconds after curing under the following curing conditions is 10% or more. Curing conditions: 3000-4000mJ / cm with 365nm ultraviolet light 2 The resin is cured by irradiating it with an integrated amount of light within the range.

[0025] In the present pressure-sensitive adhesive sheet, if the creep strain after 180 seconds at 80°C after curing is 10% or more, it is preferable because it can follow the thermal dimensional changes of the adherend without causing foaming or peeling at the interface with the adherend. From this perspective, a creep strain of 12% or more is more preferable, and of these, a creep strain of 13% or more is even more preferable, and of these, a creep strain of 15% or more is even more preferable. On the other hand, the upper limit of the creep strain after 180 seconds at 80°C is not particularly limited. However, the upper limit is about 1000%, with a preferred upper limit of 500%, more preferably 300%, and particularly preferably 100%. If the creep strain is too high, the pressure-sensitive adhesive sheet may protrude from the edge of the bonded member in a high-temperature environment, causing the edge to become sticky, or the bonded members may become misaligned. In the present pressure-sensitive adhesive sheet, the creep strain after curing can be adjusted to the above range preferably by adjusting the composition or molecular weight of the (meth)acrylic polymer (A) which is the main component resin, adjusting the type or amount of the reactive diluent (B), or adjusting the dose of active energy rays, although this is not limitative.

[0026] As mentioned above, the creep strain of this adhesive sheet is a value when the thickness is 0.8 mm to 1.5 mm. However, in order to accurately measure the creep strain of this adhesive sheet, it is necessary to avoid fluctuations in the measurement results due to the influence of the measuring jig caused by insufficient thickness of the adhesive sheet. To do this, it is necessary to adjust the thickness of this adhesive sheet to a certain range before measuring. By measuring the creep strain after pre-adjusting the thickness of the pressure-sensitive adhesive sheet to fall within the above range, the creep strain of the pressure-sensitive adhesive sheet can be accurately determined without being affected by the measuring jig.

[0027] The above phrase "when the thickness is 0.8 to 1.5 mm" means that if the thickness of the PSA sheet used as the measurement sample is less than this range, the thickness of the measurement sample is adjusted to this range by stacking several sheets, etc. The same applies when the thickness of the measurement sample is specified in other tests.

[0028] <Present Pressure-Sensitive Adhesive Resin Composition> The present pressure-sensitive adhesive resin composition is a composition containing, in addition to a (meth)acrylic polymer (A), a reactive diluent (B) and an initiator (C), if necessary, and further, if necessary, a silane coupling agent (D) and other components.

[0029] <(Meth)acrylic polymer (A)> In the present pressure-sensitive adhesive resin composition, the (meth)acrylic polymer (A) is the main component resin. That is, it is the resin with the highest mass proportion among the resins constituting the present pressure-sensitive adhesive resin composition. In this case, the mass proportion of the (meth)acrylic polymer (A) among the resins constituting the present pressure-sensitive adhesive resin composition may be 50 mass% or more, preferably 70 mass% or more, more preferably 80 mass% or more, and even more preferably 90 mass% or more (including 100 mass%).

[0030] The (meth)acrylic polymer (A) preferably contains, as a polymerization component, 50% by mass or more of a monomer component represented by the following formula 1 (wherein R1 represents a hydrogen atom or a methyl group, and R2 represents a linear or branched alkyl group having 4 to 18 carbon atoms):

[0031] Among these, the (meth)acrylic polymer (A) is more preferably one containing 55% by mass or more of the above-mentioned monomer components as polymerization components, and particularly preferably one containing 60% by mass or more of these.

[0032] In the present invention, "(meth)acrylic" encompasses acrylic and methacrylic, "(meth)acryloyl" encompasses acryloyl and methacryloyl, "(meth)acrylate" encompasses acrylate and methacrylate, and "(co)polymer" encompasses polymers and copolymers.

[0033] TIFF0007753877000001.tif22170

[0034] Examples of the monomer represented by the formula 1 include n-butyl(meth)acrylate, isobutyl(meth)acrylate, sec-butyl(meth)acrylate, t-butyl(meth)acrylate, pentyl(meth)acrylate, isopentyl(meth)acrylate, neopentyl(meth)acrylate, hexyl(meth)acrylate, cyclohexyl(meth)acrylate, heptyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, n-octyl(meth)acrylate, isooctyl(meth)acrylate, nonyl(meth)acrylate, and isononyl(meth)acrylate. Examples of suitable acrylates include butylcyclohexyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, isobornyl (meth)acrylate, 3,5,5-trimethylcyclohexane (meth)acrylate, dicyclopentanyl (meth)acrylate, and dicyclopentenyl (meth)acrylate. These may be used alone or in combination of two or more. These may be used alone or in combination of two or more. Among the above, it is particularly preferable to use at least one alkyl (meth)acrylate having an alkyl group carbon number of 4 to 18, preferably 4 to 15, such as butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, and lauryl (meth)acrylate.

[0035] The (meth)acrylic polymer (A) is preferably a copolymer having, as a copolymerization component, "another copolymerizable monomer" other than the above-mentioned monomer components.

[0036] The "other copolymerizable monomer" is preferably contained in the (meth)acrylic polymer (A) in an amount of 1 to 30% by mass, more preferably 2% by mass or more or 25% by mass or less.

[0037] Examples of the "other copolymerizable monomer" include (a) a carboxyl group-containing monomer (hereinafter also referred to as "copolymerizable monomer a1"), (b) a hydroxyl group-containing monomer (hereinafter also referred to as "copolymerizable monomer a2"), (c) an amino group-containing monomer (hereinafter also referred to as "copolymerizable monomer a3"), (d) an epoxy group-containing monomer (hereinafter also referred to as "copolymerizable monomer a4"), (e) an amide group-containing monomer (hereinafter also referred to as "copolymerizable monomer a5"), (f) an amide group-containing monomer (hereinafter also referred to as "copolymerizable monomer a6"), (g) an amide group-containing monomer (hereinafter also referred to as "copolymerizable monomer a7"), (h) an amide group-containing monomer (hereinafter also referred to as "copolymerizable monomer a8"), (i) an amide group-containing monomer (hereinafter also referred to as "copolymerizable monomer a9"), (j) an amide group-containing monomer (hereinafter also referred to as "copolymerizable monomer a1"). Examples of the copolymerizable monomer include (f) vinyl monomers (hereinafter also referred to as "copolymerizable monomer a6"), (g) (meth)acrylate monomers having an alkyl group with 1 to 3 carbon atoms (hereinafter also referred to as "copolymerizable monomer a7"), (h) macromonomers (hereinafter also referred to as "copolymerizable monomer a8"), (i) aromatic-containing monomers (hereinafter also referred to as "copolymerizable monomer a9"), and (j) other functional group-containing monomers (hereinafter "copolymerizable monomer a10"). These can be used alone or in combination of two or more.

[0038] Examples of the copolymerizable monomer a1 include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypropyl (meth)acrylate, carboxybutyl (meth)acrylate, ω-carboxypolycaprolactone mono(meth)acrylate, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 2-(meth)acryloyloxypropyl hexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxypropyl phthalic acid, 2-(meth)acryloyloxyethyl maleic acid, 2-(meth)acryloyloxypropyl maleic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxypropyl succinic acid, crotonic acid, fumaric acid, maleic acid, and itaconic acid. These may be used alone or in combination of two or more.

[0039] Examples of the copolymerizable monomer a2 include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate, which may be used alone or in combination of two or more.

[0040] Examples of the copolymerizable monomer a3 include aminoalkyl(meth)acrylates such as aminomethyl(meth)acrylate, aminoethyl(meth)acrylate, aminopropyl(meth)acrylate, and aminoisopropyl(meth)acrylate, N-alkylaminoalkyl(meth)acrylates, and N,N-dialkylaminoalkyl(meth)acrylates such as N,N-dimethylaminoethyl(meth)acrylate and N,N-dimethylaminopropyl(meth)acrylate. These may be used alone or in combination of two or more.

[0041] Examples of the copolymerizable monomer a4 include glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate glycidyl ether. These may be used alone or in combination of two or more.

[0042] Examples of the copolymerizable monomer a5 include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylolpropane(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, diacetone(meth)acrylamide, maleic acid amide, and maleimide. These may be used alone or in combination of two or more.

[0043] Examples of the copolymerizable monomer a6 include compounds having a vinyl group in the molecule. Examples of such compounds include (meth)acrylic acid alkyl esters having an alkyl group with 1 to 12 carbon atoms, functional monomers having a functional group such as a hydroxyl group, an amide group, or an alkoxylalkyl group in the molecule, polyalkylene glycol di(meth)acrylates, vinyl ester monomers such as vinyl acetate, N-vinyl-2-pyrrolidone, vinyl propionate, and vinyl laurate, and aromatic vinyl monomers such as styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene, and other substituted styrenes. These may be used alone or in combination of two or more.

[0044] Examples of the copolymerizable monomer a7 include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

[0045] The macromonomer as the copolymerizable monomer a8 is a polymer monomer having a terminal functional group and a high molecular weight backbone component. The number average molecular weight of the macromonomer is preferably 1,000 or more, more preferably 1,500 or more, and even more preferably 2,000 or more. The upper limit of the number average molecular weight is usually 10,000.

[0046] By using the copolymerizable monomer a8, a graft copolymer can be obtained in which a structural unit derived from a macromonomer is introduced as a branch component of the graft copolymer, and a (meth)acrylic polymer (A) made of such a graft copolymer can be obtained. Therefore, the properties of the graft copolymer can be changed by selecting and blending ratios of copolymerizable monomer a8 and other monomers. In particular, in the present invention, the copolymerization ratio of the macromonomer in the (meth)acrylic polymer (A) is preferably 10% by mass or less in terms of imparting fluidity during hot melting, more preferably 2% by mass or more or 9% by mass or less, particularly preferably 3% by mass or more or 8% by mass or less, and especially preferably 4% by mass or more or 7% by mass or less.

[0047] The backbone component of the macromonomer is preferably composed of a (meth)acrylic acid ester polymer or a vinyl polymer. Examples thereof include linear or branched alkyl (meth)acrylates, alicyclic alkyl (meth)acrylates, copolymerizable monomers a1, a2, and a7, each of which has 4 to 18 carbon atoms in the alkyl group, and these may be used alone or in combination of two or more.

[0048] Examples of the copolymerizable monomer a9 include benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, nonylphenol EO-modified (meth)acrylate, etc. These may be used alone or in combination of two or more.

[0049] Examples of the copolymerizable monomer a10 include (meth)acrylic-modified silicones and fluorine-containing monomers such as 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)acrylate, and 1H,1H,2H,2H-tridecafluoro-n-octyl (meth)acrylate. These may be used alone or in combination of two or more.

[0050] From the viewpoints of metal corrosion prevention and resistance to wet heat whitening, the (meth)acrylic polymer (A) preferably does not contain or substantially does not contain the "copolymerizable monomer a1." The phrase "not containing or substantially containing copolymerizable monomer a1" not only means that the copolymerizable monomer a1 is completely absent, but also means that the (meth)acrylic acid ester (co)polymer contains less than 0.5% by mass, preferably less than 0.1% by mass, of copolymerizable monomer a1.

[0051] The (meth)acrylic polymer (A) preferably contains a hydroxyl group-containing monomer and / or a nitrogen atom-containing monomer from the viewpoint of imparting adhesive strength and cohesive strength to the PSA. Therefore, the (meth)acrylic polymer (A) is particularly preferably one having the "copolymerizable monomer a2" or a nitrogen atom-containing monomer, particularly the "copolymerizable monomer a5", as a copolymerization component.

[0052] From the viewpoint of imparting hot melt properties to the pressure-sensitive adhesive, the (meth)acrylic polymer (A) preferably contains a block copolymer and / or a graft copolymer, and more preferably contains a graft copolymer. Here, the block copolymer refers to a block copolymer having a plurality of polymer chains containing repeating units derived from a (meth)acrylic acid ester, in which these polymer chains with different chemical structures are linearly bonded. Here, the graft copolymer is preferably a copolymer containing a repeating unit derived from a (meth)acrylic acid ester as the backbone component and a repeating unit derived from a macromonomer as the branch component of the graft copolymer.

[0053] In the present invention, the glass transition temperature of the (meth)acrylic polymer (A) affects the flexibility of the pressure-sensitive adhesive sheet at room temperature and the wettability of the pressure-sensitive adhesive resin composition to an adherend, i.e., the adhesiveness. Therefore, in order for the pressure-sensitive adhesive resin composition to have appropriate adhesiveness (tackiness) at room temperature, the glass transition temperature of the (meth)acrylic polymer (A) is preferably from -70°C to 0°C, and particularly preferably from -65°C or higher or -5°C or lower, and of these, particularly preferably from -60°C or higher or -10°C or lower.

[0054] In this case, the glass transition temperature of the copolymer component means a value calculated by Fox's formula from the glass transition temperature of the polymer obtained from the homopolymer of each component of the copolymer and the composition ratio.

[0055] The Fox formula is a calculated value obtained by the following formula, and can be obtained using the values ​​described in Polymer Handbook [Polymer Handbook, J. Brandrup, Interscience, 1989]. 1 / (273+Tg)=Σ(Wi / (273+Tgi)) [In the formula, Wi represents the weight fraction of monomer i, and Tgi represents the Tg (°C) of a homopolymer of monomer i.]

[0056] When obtaining the (meth)acrylic polymer (A), it is preferable that at least one of the repeating units derived from a (meth)acrylic acid ester contained in the acrylic polymer (A) has a glass transition temperature of -70 to 0°C. Examples of (meth)acrylic acid esters constituting such repeating units include (meth)acrylic acid esters having an alkyl group containing 4 to 20 carbon atoms, such as n-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, n-nonyl acrylate, n-decyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, 2-methylhexyl acrylate, isooctyl acrylate, isononyl acrylate, isodecyl acrylate, isodecyl methacrylate, isostearyl acrylate, isostearyl (meth)acrylate, multi-branched stearyl acrylate, and multi-branched stearyl (meth)acrylate, but are not limited to these.

[0057] Furthermore, at least one of the repeating units derived from a (meth)acrylic acid ester contained in the acrylic polymer (A) preferably has a glass transition temperature of 20 to 120° C. Specifically, since this affects the hot melt temperature of the pressure-sensitive adhesive sheet, the glass transition temperature (Tg) is preferably 30 to 120° C., more preferably 40° C. or higher or 110° C. or lower, and even more preferably 50° C. or higher or 100° C. or lower. If a repeating unit having such a glass transition temperature (Tg) is present, by adjusting the molecular weight, it is possible to maintain excellent processability and storage stability, and also to adjust the polymer to become hot-melt at around 80°C.

[0058] Examples of (meth)acrylic acid esters constituting such repeating units include methyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl acrylate, isobutyl acrylate, isobutyl methacrylate, isobornyl acrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 1,4-cyclohexanedimethanol monoacrylate, tetrahydrofurfuryl methacrylate, benzyl acrylate, benzyl methacrylate, phenoxyethyl acrylate, and phenoxyethyl methacrylate.

[0059] In the present invention, when the (meth)acrylic polymer (A) is a block copolymer or a graft copolymer, a pressure-sensitive adhesive sheet having excellent shape stability and hot melt properties can be obtained. Block copolymers and graft copolymers can be produced by known methods, and graft copolymers in particular can be produced by using a macromonomer as a copolymerization component, as described above.

[0060] When the (meth)acrylic polymer (A) is a copolymer containing structural units derived from macromonomers as branch components as described above, the (meth)acrylic polymer preferably contains 10 mass % or less, more preferably 2 to 9 mass %, of the structural units derived from macromonomers relative to the (meth)acrylic polymer in order to impart hot-melt properties. If the structural units derived from macromonomers are 10 parts by mass or less, this is preferred in terms of imparting fluidity during hot-melt. Furthermore, if the structural units derived from macromonomers are 2 mass % or more, this is preferred in terms of suppressing excessive flow during storage or hot-melt. From this viewpoint, the structural units derived from the macromonomer are more preferably 3% by mass or more, and particularly preferably 4% by mass or more, while being more preferably 9% by mass or less, particularly preferably 9% by mass or less, especially preferably 8% by mass or less, and even more preferably 7% by mass or less.

[0061] The glass transition temperature of the structural unit derived from the macromonomer is preferably 20 to 150°C, more preferably 40°C or higher or 130°C or lower, and even more preferably 60°C or higher or 120°C or lower.

[0062] <Reactive diluent (B)> The reactive diluent (B) is not simply a diluent, but a compound or composition that undergoes a polymerization reaction or a crosslinking reaction by a radical reaction caused by active energy rays, and bonds with the (meth)acrylic polymer or forms a physical crosslink.

[0063] The reactive diluent (B) preferably contains a polyfunctional (meth)acrylate component (b-1) having two or more (meth)acryloyl groups to ensure that the pressure-sensitive adhesive sheet is cured by irradiation with active energy rays, and further contains a monofunctional (meth)acrylate component (b-2) having one (meth)acryloyl group to improve the ability to follow thermal dimensional changes of the adherend.

[0064] The pressure-sensitive adhesive resin composition contains a polyfunctional (meth)acrylate component (b-1) having two or more (meth)acryloyl groups as the reactive diluent (B), which allows the pressure-sensitive adhesive resin composition to form a crosslinked structure, accelerating the crosslinking reaction of the (meth)acrylic polymer (A) and accelerating the curing of the pressure-sensitive adhesive resin composition. Furthermore, the inclusion of a monofunctional (meth)acrylate component (b-2) having one (meth)acryloyl group increases the molecular weight between crosslink points of the cured product, increasing the degree of freedom of movement of the molecular chain. Therefore, when an adherend is laminated with the pressure-sensitive adhesive sheet interposed therebetween, even if the adherend undergoes dimensional deformation due to repeated heating and cooling, the pressure-sensitive adhesive sheet made of the pressure-sensitive adhesive resin composition can deform accordingly.

[0065] From this viewpoint, it is preferable that the reactive diluent (B) contains a polyfunctional (meth)acrylate component (b-1) and a monofunctional (meth)acrylate component (b-2), and in this case, the mass ratio of the components (b-1):(b-2) is preferably 1:0.1 to 1:9, more preferably 1:1 to 1:9, and even more preferably 1:2 to 1:9. When the content is within this range, the monofunctional (meth)acrylate component (b-2) is not too high, and there is no risk of reduced light sensitivity and reduced productivity, and the composition can sufficiently conform to the adherend.

[0066] The content of the reactive diluent (B) is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, relative to 100 parts by mass of the (meth)acrylic polymer (A). The upper limit is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less.

[0067] Furthermore, from the viewpoint of forming a crosslinked structure and imparting cohesive strength after curing, the content of the polyfunctional (meth)acrylate component (b-1) is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and particularly preferably 1.5 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic polymer (A). The upper limit is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and particularly preferably 6 parts by mass or less.

[0068] The content of the monofunctional (meth)acrylate component (b-2) is preferably 2 parts by mass or more, more preferably 4 parts by mass or more, and particularly preferably 6 parts by mass or more, per 100 parts by mass of the (meth)acrylic polymer (A) in order to adjust the crosslink density and impart appropriate flexibility to the cured product. The upper limit is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and particularly preferably 15 parts by mass or less.

[0069] The polyfunctional (meth)acrylate component (b-1) is preferably a component having a glass transition temperature of higher than 0°C when made into a homopolymer, more preferably 5°C or higher, and even more preferably 10°C or higher. The upper limit is usually 250°C. On the other hand, the monofunctional (meth)acrylate component (b-2) is preferably a component having a glass transition temperature of 0°C or lower when made into a homopolymer, more preferably -10°C or lower, and even more preferably -20°C or lower. The lower limit is usually -80°C. By including the monofunctional (meth)acrylate component (b-2) having a low glass transition temperature, the composition hardens slowly even after curing, and therefore deforms in response to dimensional changes in the adherend. This makes it possible to prevent peeling and bubbles from occurring, even in durability tests involving repeated heating and cooling. Here, the glass transition temperature means the maximum value of the loss tangent (tan δ) obtained by measuring dynamic viscoelasticity at a frequency of 1 Hz.

[0070] Examples of the polyfunctional (meth)acrylate component (b-1) include 1,4-butanediol di(meth)acrylate, glycerin di(meth)acrylate, neopentyl glycol di(meth)acrylate, glycerin glucidyl ether di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-Nonanediol di(meth)acrylate, tricyclodecane dimethacrylate, tricyclodecane dimethanol di(meth)acrylate, bisphenol A polyethoxydi(meth)acrylate, bisphenol A polypropoxydi(meth)acrylate, bisphenol F polyethoxydi(meth)acrylate, ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane trioxyethyl (meth)acrylate, ε- Caprolactone-modified tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propoxylated pentaerythritol tri(meth)acrylate, ethoxylated pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, dipentaerythritol Examples of the acrylic monomer include ultraviolet-curable polyfunctional (meth)acrylic monomers such as di(meth)acrylate, polyethylene glycol di(meth)acrylate, tris(acryloxyethyl)isocyanurate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol penta(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, di(meth)acrylate of an ε-caprolactone adduct of hydroxypivalic acid neopentyl glycol, trimethylolpropane tri(meth)acrylate, trimethylolpropane polyethoxytri(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate, as well as polyfunctional (meth)acrylic oligomers such as polyester(meth)acrylate, epoxy(meth)acrylate, urethane(meth)acrylate, and polyether(meth)acrylate. These may be used alone or in combination of two or more.

[0071] Examples of the monofunctional (meth)acrylate component (b-2) include ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, and decyl (meth)acrylate. Decyl (meth)acrylate, isododecyl (meth)acrylate, tetradecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, behenyl (meth)acrylate, cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, cyclooctyl (meth)acrylate, cyclononyl (meth)acrylate, cyclodecyl (meth)acrylate, isobornyl (meth)acrylate Acrylate, norbornyl (meth)acrylate, adamantyl (meth)acrylate, tricyclodecane dimethanol acrylate, ethoxylated-o-phenylphenol acrylate, 2-hydroxy-o-phenylphenol propyl acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, phenoxyethylene glycol (meth)acrylate, phenoxydiethylene glycol Licorice (meth)acrylate, phenoxy polyethylene glycol (meth)acrylate, 2-hydroxy-o-phenylphenol propyl acrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl tetrahydrophthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, 2-(meth)acryloyloxypropyl phthalate, 2-(meth)acryloyloxypropyl hydrophthalate, 2-(meth)acryloyloxypropyl hexahydrophthalate, etc. benzyl (meth)acrylate,Benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxyethylene glycol (meth)acrylate, 2-naphthyl (meth)acrylate, 9-anthracenyl (meth)acrylate, 1-pyrenylmethyl (meth)acrylate, benzyl (meth)acrylate, tricyclodecane dimethanol monoacrylate monocarboxylic acid, dicyclopentanyl acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, trimethylolpropane mono(meth)acrylate, glycerin mono(meth)acrylate, pentaerythritol mono(meth)acrylate, diglycerin mono(meth)acrylate, ditrimethylolpropane mono(meth)acrylate, di Examples include pentaerythritol mono(meth)acrylate, ethoxylated trimethylolpropane mono(meth)acrylate, propoxylated trimethylolpropane mono(meth)acrylate, ethoxylated glycerin mono(meth)acrylate, propoxylated glycerin mono(meth)acrylate, ethoxylated pentaerythritol mono(meth)acrylate, propoxylated pentaerythritol mono(meth)acrylate, ethoxylated ditrimethylolpropane mono(meth)acrylate, propoxylated ditrimethylolpropane mono(meth)acrylate, alkylene oxide-modified diglycerin mono(meth)acrylate, and alkylene oxide-modified dipentaerythritol mono(meth)acrylate, as well as monofunctional oligomers such as monofunctional urethane (meth)acrylate, monofunctional epoxy (meth)acrylate, and monofunctional polyester (meth)acrylate. These may be used alone or in combination of two or more.

[0072] <Initiator (C)> The initiator (C) may be any compound that generates radicals when exposed to active energy rays. Initiators (C) are broadly classified into two types based on the radical generation mechanism: cleavage-type photoinitiators, which can generate radicals by cleaving and decomposing the single bond of the initiator itself, and hydrogen abstraction-type photoinitiators, which form an exciplex between the excited initiator and the hydrogen donor in the system and can transfer hydrogen from the hydrogen donor.

[0073] The initiator (C) may be either a cleavage-type photoinitiator or a hydrogen-abstraction-type photoinitiator, and may be used either alone or in combination of two or more of them.

[0074] Examples of the cleavage-type photoinitiator include 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-(4-(2-hydroxyethoxy)phenyl)-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-[4-{4-(2-hydroxy-2-methyl-propionyl)benzyl}phenyl]-2-methyl-propan-1-one, oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone), methyl phenylglyoxylate, 2-benzyl-2-dimethylamino-1-(4 2-(4-morpholinophenyl)butan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)2,4,4-trimethylpentylphosphine oxide, and derivatives thereof can be given.

[0075] Examples of hydrogen abstraction photoinitiators include benzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 4-(meth)acryloyloxybenzophenone, methyl 2-benzoylbenzoate, methyl benzoylformate, bis(2-phenyl-2-oxoacetic acid)oxybisethylene, 4-(1,3-acryloyl-1,4,7,10,13-pentaoxotridecyl)benzophenone, thioxanthone, 2-chlorothioxanthone, 3-methylthioxanthone, 2,4-dimethylthioxanthone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, and derivatives thereof.

[0076] The content of the initiator (C) is not particularly limited, but as a guideline, it is preferably contained in an amount of 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, and even more preferably 1 to 3 parts by mass, per 100 parts by mass of the (meth)acrylic polymer (A).

[0077] <Silane coupling agent (D)> The silane coupling agent (D) can improve adhesiveness, particularly adhesive strength to glass materials.

[0078] Examples of the silane coupling agent include compounds having an unsaturated group such as a vinyl group, an acryloxy group, or a methacryloxy group, an amino group, an epoxy group, or the like, as well as a hydrolyzable functional group such as an alkoxy group. Specific examples of silane coupling agents include N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane. Of these, in the present pressure-sensitive adhesive layer, γ-glycidoxypropyltrimethoxysilane or γ-methacryloxypropyltrimethoxysilane can be preferably used from the viewpoints of good adhesiveness and little discoloration such as yellowing. The silane coupling agents can be used alone or in combination of two or more.

[0079] The content of the silane coupling agent (D) is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, based on 100 parts by mass of the (meth)acrylic polymer (A). Similar to the silane coupling agent, a coupling agent such as an organic titanate compound can also be effectively used.

[0080] <Other ingredients> As "other components" other than those described above contained in the present pressure-sensitive adhesive resin composition, for example, various additives such as a tackifier resin, an antioxidant, a light stabilizer, a metal deactivator, an anti-aging agent, a moisture absorber, a polymerization inhibitor, an ultraviolet absorber, a rust inhibitor, and inorganic particles can be appropriately contained as needed. If necessary, a reaction catalyst such as a tertiary amine compound, a quaternary ammonium compound, or a tin laurate compound may be appropriately contained.

[0081] (Block copolymer or graft copolymer) The present adhesive resin composition may contain a block copolymer and / or a graft copolymer as a polymer other than the (meth)acrylic polymer (A) in order to impart hot-melt properties to the present adhesive sheet. These copolymers preferably have at least one rubbery segment and one glassy segment.

[0082] Here, the term "block copolymer" refers to a block copolymer having a plurality of polymer chains containing repeating units derived from a certain monomer, and in which these polymer chains with different chemical structures are linearly bonded. The graft copolymer refers to a copolymer that contains a repeating unit derived from a monomer as the backbone component and a repeating unit derived from a monomer different from the backbone component as the branch component of the graft copolymer.

[0083] The rubbery segment is a portion that exhibits a glass transition temperature (Tg) below room temperature, and the Tg of the rubbery segment is preferably below 0°C, more preferably below -10°C, and even more preferably below -20°C. Examples of monomers constituting the rubbery segments include conjugated dienes and hydrogenated derivatives of conjugated dienes, where the conjugated dienes preferably contain 4 to 15 carbon atoms. Examples of conjugated dienes include butadiene, isoprene, ethylbutadiene, phenylbutadiene, piperylene, pentadiene, hexadiene, ethylhexadiene, and dimethylbutadiene. The polymerized conjugated dienes can be used individually or as copolymers with each other. In some embodiments, the conjugated diene is selected from the group consisting of isoprene, butadiene, ethylene butadiene copolymers, and combinations thereof.

[0084] The glassy segment is a portion that exhibits a Tg above room temperature, and the Tg of the glassy segment is 40°C or higher, preferably 60°C or higher, and more preferably 80°C or higher. Examples of monomers that make up the glassy segment include, but are not limited to, monovinyl aromatic monomers, such as styrene, vinylpyridine, vinyltoluene, α-methylstyrene, methylstyrene, dimethylstyrene, ethylstyrene, diethylstyrene, t-butylstyrene, di-n-butylstyrene, isopropylstyrene, other alkylated styrenes, styrene analogs, and styrene homologs.

[0085] The content by mass of the block copolymer and / or graft copolymer other than the (meth)acrylic polymer (A) is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 5 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic polymer (A). The upper limit is preferably 100 parts by mass or less, more preferably 95 parts by mass or less, and even more preferably 90 parts by mass or less.

[0086] (plasticizer) The present adhesive resin composition may contain a plasticizer in order to impart hot-melt properties to the present adhesive sheet.

[0087] Non-limiting examples of plasticizers include those selected from the group consisting of polyisobutylene, polyisoprene, polybutadiene, amorphous polyolefins and copolymers thereof, silicones, polyacrylates, oligomeric polyurethanes, ethylene propylene copolymers, and any combination or mixture thereof. Among these, the plasticizer is preferably polyisobutylene. Examples of polyisobutylene plasticizers that can be used herein include those commercially available from BASF under the trade name OPPANOL, particularly those selected from the OPPANOLB series.

[0088] From the viewpoint of environmental protection, it is preferable that the volatile organic compound (VOC) value of the plasticizer used is small, and when measured by thermogravimetric analysis, it is preferably less than 1000 ppm, more preferably less than 800 ppm, even more preferably less than 600 ppm, and most preferably less than 400 ppm.

[0089] The content of the plasticizer by mass is not particularly limited, but is preferably 0.1 to 20 parts by mass, more preferably 0.5 parts by mass or more or 15 parts by mass or less, per 100 parts by mass of the (meth)acrylic polymer (A).

[0090] (hydrocarbon tackifier) The adhesive resin composition may contain a hydrocarbon tackifier to impart hot-melt properties to the adhesive sheet. Examples of hydrocarbon tackifiers include terpene resins such as polyterpenes (e.g., α-pinene resins, β-pinene resins, and limonene resins) and aromatic-modified polyterpene resins (e.g., phenol-modified polyterpene resins), coumaran-indene resins, petroleum-based resins such as C5 hydrocarbon resins, C9 hydrocarbon resins, C5 / C9 hydrocarbon resins, and dicyclopentadiene resins, and rosins such as modified rosin, hydrogenated rosin, polymerized rosin, and rosin esters. Preferably, the hydrocarbon tackifier is compatible with the adhesive composition.

[0091] The content by mass of the hydrocarbon tackifier is not particularly limited, but is preferably 0.1 to 20 parts by mass, more preferably 0.5 parts by mass or more or 15 parts by mass or less, per 100 parts by mass of the (meth)acrylic polymer (A).

[0092] By including these plasticizers and hydrocarbon tackifiers, a hot-melt adhesive composition having adhesive properties can be suitably produced.

[0093] <Method for preparing the present pressure-sensitive adhesive resin composition> The present pressure-sensitive adhesive resin composition can be obtained by mixing, in addition to the (meth)acrylic polymer (A), preferably further a reactive diluent (B), an initiator (C), and, if necessary, a silane coupling agent (D), and other components in predetermined amounts. There are no particular limitations on the method for mixing these components, and there are no particular limitations on the order in which the components are mixed. A heat treatment step may be added during the production of the pressure-sensitive adhesive resin composition. In this case, it is desirable to mix the components of the pressure-sensitive adhesive resin composition in advance and then perform the heat treatment. A master batch prepared by concentrating various mixed components may also be used.

[0094] The mixing device is not particularly limited, and for example, a universal mixer, a planetary mixer, a Banbury mixer, a kneader, a gate mixer, a pressure kneader, a three-roll mill, or a two-roll mill can be used. If necessary, a solvent can be used in the mixing. The present pressure-sensitive adhesive resin composition can be used as a solvent-free system, which does not contain a solvent. By using it as a solvent-free system, no solvent remains, which has the advantage of improving heat resistance and light resistance.

[0095] <Layers other than the adhesive layer> In the present invention, the pressure-sensitive adhesive sheet preferably has a multi-layer structure of two or more layers from the viewpoint of improving the storage stability, processability, and adhesive properties of the pressure-sensitive adhesive sheet, and in such a case, it is preferable to have an intermediate layer as a layer other than the pressure-sensitive adhesive layer, and for example, the composition of the intermediate layer is optional. However, from the viewpoint of further improving interlayer adhesion, it is preferable that the resin composition forming the layer other than the pressure-sensitive adhesive layer also contains the (meth)acrylic polymer (A) as a main component resin, and in particular, it is preferable that it contains the same (meth)acrylic polymer (A) as the pressure-sensitive adhesive layer as a main component resin. Furthermore, it is more preferable that layers other than the pressure-sensitive adhesive layer also contain the reactive diluent (B) and the initiator (C).In this case, it is more preferable that the reactive diluent (B) contains a polyfunctional (meth)acrylate component (b-1) and a monofunctional (meth)acrylate component (b-2).

[0096] <Usage of this adhesive sheet> The present pressure-sensitive adhesive sheet can also be used as a single pressure-sensitive adhesive sheet. For example, the present pressure-sensitive adhesive resin composition can be directly applied to an adherend to form a sheet, or the present pressure-sensitive adhesive resin composition can be directly extruded or injected into a mold to form the pressure-sensitive adhesive sheet. Furthermore, the present pressure-sensitive adhesive sheet can also be used by directly filling the present pressure-sensitive adhesive resin composition between components such as conductive components.

[0097] On the other hand, the present PSA sheet can also be used as a PSA sheet laminate with a release film, which comprises a PSA layer formed from the present PSA resin composition and a release film. For example, the present PSA resin composition can be formed into a single-layer or multi-layer PSA sheet with a release film on a release film.

[0098] Examples of materials for the release film include polyester film, polyolefin film, polycarbonate film, polystyrene film, acrylic film, triacetyl cellulose film, fluororesin film, etc. Among these, polyester film and polyolefin film are particularly preferred.

[0099] The thickness of the release film is not particularly limited, but from the viewpoint of processability and handling, it is preferably 25 μm to 500 μm, more preferably 38 μm or more or 250 μm or less, and even more preferably 50 μm or more or 200 μm or less.

[0100] <This laminate> A laminate for an image display device (referred to as "the present laminate") according to one embodiment of the present invention is a laminate for constituting an image display device having a configuration in which the present adhesive sheet is interposed between two components for an image display device, and the two components for an image display device are laminated via the present adhesive sheet. When the adhesive sheet of the present laminate is irradiated with active energy rays, the adhesive sheet is cured (the adhesive sheet after curing is referred to as the "cured adhesive sheet"), and two components for an image display device can be bonded together.

[0101] In this case, at least one of the two image display device components can be a laminate consisting of one or a combination of two or more selected from the group consisting of a touch sensor, an image display panel, a surface protection panel, a polarizing film, and a retardation film.

[0102] In particular, at least one of the two image display device components has a depth (mm) / base area (mm 2 ) ratio is 1.0 × 10 -5 ~3.0×10 -1 , among which 5.0 × 10 -5 or more than 2.0 x 10 -1 Below, among them, 1.0 × 10 -4 or more than 1.0×10 -1 If the adhesive sheet has the following bottomed holes, the effects of the adhesive sheet can be more effectively enjoyed. In this case, the resin composition of the pressure-sensitive adhesive sheet can be filled into the bottomed holes so that no voids with a diameter of at least 1 mm or more are present in the bottomed holes. Note that the "diameter of the void" refers to the longest diameter in the case of non-spherical voids.

[0103] Specific examples of the present laminate include configurations such as release film / present adhesive sheet or present cured adhesive sheet / touch panel, image display panel / present adhesive sheet or present cured adhesive sheet / touch panel, image display panel / present adhesive sheet or present cured adhesive sheet / touch panel / present adhesive sheet or present cured adhesive sheet / protective panel, polarizing film / present adhesive sheet or present cured adhesive sheet / touch panel, and polarizing film / present adhesive sheet or present cured adhesive sheet / touch panel / present adhesive sheet or present cured adhesive sheet / protective panel.

[0104] The touch panel includes a structure in which a touch panel function is built into a protection panel, and a structure in which a touch panel function is built into an image display panel. Therefore, the present laminate may have a configuration such as release film / present adhesive sheet or present cured adhesive sheet / protective panel, release film / present adhesive sheet or present cured adhesive sheet / image display panel, or image display panel / present adhesive sheet or present cured adhesive sheet / protective panel. Furthermore, in the above-mentioned configuration, all configurations in which the conductive layer is interposed between the present pressure-sensitive adhesive sheet or the present cured pressure-sensitive adhesive sheet and an adjacent member such as a touch panel, a protective panel, an image display panel, a polarizing film, etc. can be mentioned, but the present invention is not limited to these lamination examples.

[0105] The touch panel may be of a resistive type, a capacitance type, an electromagnetic induction type, etc. Among these, the capacitance type is preferred.

[0106] The material of the protective panel may be glass or a plastic such as an acrylic resin, a polycarbonate resin, an alicyclic polyolefin resin such as a cycloolefin polymer, a styrene resin, a polyvinyl chloride resin, a phenolic resin, a melamine resin, or an epoxy resin.

[0107] The image display panel is composed of a polarizing film and other optical films such as retardation films, a liquid crystal material, and a backlight system (usually, the surface of the adhesive resin composition or adhesive article that is adhered to the image display panel is an optical film), and depending on the control method of the liquid crystal material, there are STN method, VA method, IPS method, etc., and any of these methods may be used.

[0108] The present laminate can be used as a component of image display devices such as liquid crystal displays, organic EL displays, inorganic EL displays, electronic paper, plasma displays, and microelectromechanical system (MEMS) displays.

[0109] <Method of manufacturing a laminate for constituting an image display device> Next, an example of a method for producing the present laminate will be described, although the method for producing the present laminate is not limited to the method described below.

[0110] The present laminate is produced by laminating the present pressure-sensitive adhesive sheet to one surface of a first image display device component to form a bonded body, and then bringing the adhesive sheet of the bonded body face-to-face with the surface to be bonded of a second image display device component having a bottomed hole on the bonded surface, and laminating them in close contact under reduced pressure to form a laminate. Next, the laminate is subjected to a heat and pressure treatment to hot-melt the present pressure-sensitive adhesive sheet, thereby flowing the pressure-sensitive adhesive resin composition into the bottomed hole of the second image display device component. Next, the present pressure-sensitive adhesive sheet sandwiched between the first and second image display device components is irradiated with active energy rays to cure the present pressure-sensitive adhesive sheet.

[0111] In this case, the heat and pressure treatment of the present laminate is preferably carried out at a temperature of 50° C. to 80° C. and at a pressure of 0.2 MPa to 0.8 MPa. In particular, the temperature is preferably 53°C or higher or 78°C or lower, and more preferably 55°C or higher or 75°C or lower. The pressure is preferably 0.25 MPa or more or 0.75 MPa or less, and more preferably 0.30 MPa or more or 0.70 MPa or less. The treatment time, in other words, the time for which the pressure is applied, is preferably 5 minutes or more, more preferably 5 minutes or more or 60 minutes or less, and even more preferably 10 minutes or more or 45 minutes or less.

[0112] In the present invention, ultraviolet light and visible light are suitable as the active energy rays in the above-mentioned active energy ray irradiation. Examples of light sources for irradiating active energy rays include high-pressure mercury lamps, metal halide lamps, xenon lamps, halogen lamps, LED lamps, and fluorescent lamps, and any of these can be used depending on the wavelength and dose of light to be irradiated. The irradiation time and irradiation means are not particularly limited. For example, in the case of ultraviolet irradiation, the cumulative light amount at a wavelength of 365 nm is 100 mJ / cm. 2 ~10,000mJ / cm 2is preferred, and more preferably 500 mJ / cm 2 ~8000mJ / cm 2 , and more preferably 1000 mJ / cm 2 ~6000mJ / cm 2 , particularly preferably 1500 mJ / cm 2 ~4000mJ / cm 2 is.

[0113] A preferred example of the present laminate is a laminate for constituting an image display device, which comprises two image display device components laminated via a cured pressure-sensitive adhesive sheet having a thickness of 0.8 to 1.5 mm, and which exhibits a creep strain of 10% or more after 180 seconds at 80°C after curing under specified curing conditions. The cured pressure-sensitive adhesive sheet is the pressure-sensitive adhesive sheet after photo-curing. At this time, as described above, at least one of the components of the image display device has a depth (mm) / base area (mm 2 ) is 1.0 × 10 -5 ~3.0×10 -1 In this case, the bottomed holes are filled with the pressure-sensitive adhesive sheet after curing, and it is preferable that the bottomed holes are filled in such a manner that no voids with a diameter of at least 1 mm or more exist. The "pore diameter" means the longest diameter when the pore is non-spherical.

[0114] <This image display device> An image display device according to an example of an embodiment of the present invention (also referred to as "the present image display device") is an image display device including the present image display device constituting laminate. Specific examples of the image display device include a liquid crystal display, an organic EL display, an inorganic EL display, electronic paper, a plasma display, and a microelectromechanical system (MEMS) display.

[0115] <Explanation of terms> In the present invention, when the expression "X to Y" (X and Y are any numbers) is used, unless otherwise specified, it means "X or more and Y or less," as well as "preferably larger than X" or "preferably smaller than Y." Furthermore, when it is expressed as "X or more" (X is any number) or "Y or less" (Y is any number), it also includes the intention that "it is preferable that it is greater than X" or "it is preferable that it is less than Y." In the present invention, the term "sheet" conceptually encompasses sheets, films, and tapes. [Example]

[0116] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0117] <(Meth)acrylic polymer> (Meth)acrylic polymer A-1: ​​an acrylic copolymer (mass average molecular weight: 160,000, glass transition temperature: -36°C) obtained by random copolymerization of 15 parts by mass of polymethyl methacrylate macromonomer (glass transition temperature: 105°C) having a number average molecular weight of 2400, 81 parts by mass of butyl acrylate (glass transition temperature: -55°C), and 4 parts by mass of acrylic acid (glass transition temperature: 106°C). (Meth)acrylic polymer A-2: an acrylic copolymer (mass average molecular weight: 220,000, glass transition temperature: -45°C) obtained by random copolymerization of 6 parts by mass of polymethyl methacrylate macromonomer (glass transition temperature: 105°C) having a number average molecular weight of 2400, 90 parts by mass of butyl acrylate (glass transition temperature: -55°C), and 4 parts by mass of acrylic acid (glass transition temperature: 106°C). (Meth)acrylic polymer A-3: an acrylic polymer (mass average molecular weight: 430,000, glass transition temperature: -50°C) consisting of 64 parts by mass of 2-ethylhexyl acrylate (glass transition temperature: -70°C), 17 parts by mass of 2-hydroxyethyl acrylate (glass transition temperature: -15°C), and 19 parts by mass of methyl acrylate (glass transition temperature: 8°C).

[0118] The glass transition temperature of each copolymer component in the (meth)acrylic polymer is a literature value of the glass transition temperature obtained from a homopolymer of the component. For the macromonomer, the literature value of the glass transition temperature obtained from a homopolymer of the component that forms the high molecular weight skeleton in the macromonomer is listed. The glass transition temperature of the (meth)acrylic copolymer is a value calculated by Fox's formula from the glass transition temperatures and constituent ratios of the above-mentioned respective copolymerization components.

[0119] <Reactive diluent> Reactive diluent b-1-1: propoxylated pentaerythritol triacrylate (glass transition temperature when homopolymerized: 62°C) Reactive diluent b-1-2: Nonanediol diacrylate (glass transition temperature when homopolymerized: 38°C) Reactive diluent b-1-3: Polytetramethylene glycol diacrylate (glass transition temperature when homopolymerized: -60°C) Reactive diluent b-2-1: 4-hydroxybutyl acrylate (glass transition temperature when homopolymerized: -57°C) Reactive diluent b-2-2: Propylene glycol skeleton-containing monofunctional urethane acrylate (AGC "PEM-X264", mass average molecular weight: 10,000, (glass transition temperature when homopolymerized: -62°C))

[0120] The glass transition temperature of the above reactive diluents when converted into homopolymers was measured as follows. To 100 g of the reactive diluent, 1 g of photopolymerization initiator (IGM's "Esacure TZT") was added. A silicone resin sheet frame with an opening of 4 mm in width, 37 mm in length, and 0.6 mm in thickness was laminated on a 0.55 mm thick soda lime glass, and the reactive diluent was poured into the frame. A 0.55 mm thick soda lime glass was placed on top of it, and ultraviolet light was applied at 365 nm with an integrated light intensity of 4000 mJ / cm. 2The reactive diluent was cured by irradiating it from both sides through soda-lime glass so that the cured polymer was a homopolymer composed of the reactive diluent. The resulting sample was subjected to dynamic viscoelasticity measurements using a viscoelasticity measuring device (IT Measurement & Control Co., Ltd., "DVA-200") at a frequency of 1 Hz, a heating rate of 3°C / min, and a measurement temperature range of -70°C to 130°C. The peak temperature of Tan δ obtained from the viscoelasticity curve was taken as the glass transition temperature (Tg).

[0121] <Initiator> Photopolymerization initiator C-1: A mixture of 2,4,6-trimethylbenzophenone and 4-methylbenzophenone (IGM "Esacure TZT") Photopolymerization initiator C-2: IGM "Esacure KTO46"

[0122] <Silane coupling agent> Silane coupling agent D-1: γ-glycidoxypropyltrimethoxysilane (Shin-Etsu Silicones "KBM403")

[0123] <Other ingredients> Hydrocarbon tackifier E-1: Terpene phenol resin (Yasuhara Chemical Co., Ltd. "YS Polystar G125") Hydrocarbon tackifier E-2: Terpene phenol resin (Yasuhara Chemical Co., Ltd. "YS Polystar T160")

[0124] [Example 1] 100 parts by mass of (meth)acrylic polymer A-1, 2.5 parts by mass of reactive diluent b-1-1, 7.5 parts by mass of reactive diluent b-2-1, 1.5 parts by mass of photopolymerization initiator C-1, and 0.3 parts by mass of silane coupling agent D-1 were prepared as raw materials for the adhesive layer. On the other hand, 100 parts by mass of (meth)acrylic polymer A-1, 0.5 parts by mass of reactive diluent b-1-1, 1.5 parts by mass of reactive diluent b-2-1, and 1.5 parts by mass of photopolymerization initiator C-1 were prepared as raw materials for the intermediate layer. The raw materials for the adhesive layer and the intermediate layer were fed into two extruders, respectively, and co-extruded in a layer structure of two types and three layers (adhesive layer / intermediate layer / adhesive layer, thickness 1:1:1) to obtain an adhesive sheet.

[0125] Next, the adhesive sheet was sandwiched between two polyethylene terephthalate films with release-treated surfaces (Diafoil MRV (V03) manufactured by Mitsubishi Chemical Corporation, thickness 100 μm, and Diafoil MRQ manufactured by Mitsubishi Chemical Corporation, thickness 75 μm), i.e., two release films, and hot-melt molded into a sheet with a thickness of 150 μm, to obtain an adhesive sheet laminate consisting of release film / adhesive sheet 1 / release film. The adhesive sheet 1 was a photocurable adhesive sheet that was cured by irradiation with light.

[0126] [Examples 2 to 11, Comparative Examples 1 to 3] As shown in Table 1, pressure-sensitive adhesive sheets 2 to 14 and pressure-sensitive adhesive sheet laminates were produced in the same manner as in Example 1, except that the composition and layer structure of each layer were changed.

[0127] [Physical property measurement and evaluation] The following various measurements and evaluations were carried out on the pressure-sensitive adhesive sheets 1 to 14 produced in the above Examples and Comparative Examples. The evaluation results are summarized in Table 1.

[0128] <Creep test> (pre-cure creep) A plurality of each of the pressure-sensitive adhesive sheets prepared in the examples and comparative examples were laminated to a thickness of 0.8 to 1.5 mm, and punched out into a circle with a diameter of 8 mm. Using a rheometer (TA Instruments "DHR-2"), the strain (%) after 1200 seconds was measured under the following conditions: measurement jig: 8 mm diameter parallel plates, temperature: 50°C, pressure: 1000 Pa, torque: 100 μN·m.

[0129] (Post-cure creep) The pressure-sensitive adhesive sheets produced in the examples and comparative examples were irradiated with a high-pressure mercury lamp at 365 nm with an integrated light intensity of 4000 mJ / cm2 The adhesive sheet was cured by irradiating it with ultraviolet light through a release-treated polyethylene terephthalate film so that the ultraviolet light was irradiated at 365 nm with an integrated light intensity of 4000 mJ / cm 2 for adhesive sheet 8 of Example 8 and adhesive sheet 11 of Example 11. 2 instead of 3000mJcm 2 The adhesive sheet was cured by irradiating it so that the temperature became The cured adhesive sheets were laminated to a thickness of 0.8 to 1.5 mm, and punched out into a circle with a diameter of 8 mm. Using a rheometer (TA Instruments "DHR-2"), the strain (%) after 180 seconds was measured under the following conditions: measurement jig: 8 mm diameter parallel plates, temperature: 80°C, pressure: 1000 Pa, torque: 100 μN·m.

[0130] <Adhesive strength> (Adhesive strength before curing) One release film was peeled off from the pressure-sensitive adhesive sheets produced in the Examples and Comparative Examples, and a 100 μm thick polyethylene terephthalate film (Cosmoshine A4300, manufactured by Toyobo Co., Ltd.) was attached as a backing film to prepare a laminate. The laminate was cut to a length of 150 mm and a width of 10 mm, and the remaining release film was peeled off to expose the adhesive surface, which was then roll-pressed onto a soda lime glass with a 2 kg roll going back and forth once to adhere the adhesive sheet to the surface. The adhesive sheet was then cured at 60°C for 30 minutes to complete the application. The adhesive strength (N / cm) of this adhesive strength measurement sample was measured when it was peeled off from the glass at a peel angle of 180° and a peel speed of 60 mm / min in an environment of 23°C and 40% RH, and the adhesive strength before curing was determined.

[0131] (Adhesive strength after curing) One release film was peeled off from the pressure-sensitive adhesive sheets produced in the Examples and Comparative Examples, and a 100 μm thick polyethylene terephthalate film (Cosmoshine A4300, manufactured by Toyobo Co., Ltd.) was attached as a backing film to prepare a laminate. The laminate was cut to a length of 150 mm and a width of 10 mm, and the remaining release film was peeled off to expose the adhesive surface. The adhesive sheet was roll-pressed onto a soda lime glass by rolling a 2 kg roll back and forth once. The laminate was then aged at 60°C for 30 minutes for finish application, and then exposed to ultraviolet light at 365 nm with an integrated light intensity of 4000 mJ / cm2 through the backing film. 2 The adhesive sheet was cured by irradiating it so that the temperature was such that the adhesive strength was measured. The adhesive sheet was then cured for 15 hours to prepare a sample for measuring adhesive strength. However, for the adhesive sheet 8 of Example 8 and the adhesive sheet 11 of Example 11, ultraviolet light was irradiated through soda lime glass at 365 nm with an integrated light intensity of 4000 mJ / cm 2 2 instead of 3000mJ / cm 2 The adhesive sheet was cured by irradiation so as to obtain a sample for reliability evaluation. The adhesive strength (N / cm) of this adhesive strength measurement sample was measured when it was peeled off from the glass at a peel angle of 180° and a peel speed of 60 mm / min in an environment of 23°C and 40% RH, and the adhesive strength after curing was determined.

[0132] <Hole filling ability> A 20 μm thick double-sided adhesive sheet was laminated onto one side of a 100 μm thick polyethylene terephthalate film (Cosmoshine A4300 manufactured by Toyobo Co., Ltd.) using a hand roll to prepare a polyethylene terephthalate film with an adhesive layer (total thickness 120 μm). The polyethylene terephthalate film with the adhesive layer was cut into a piece of 54 mm × 82 mm, and bottomed holes with a diameter of 4 mm were punched in the four corners of the cut film so that the distance from the edge to the center of the hole was 6 mm. The film was roll-attached to a soda lime glass sheet measuring 54 mm×82 mm and 0.55 mm thick to prepare a substrate for evaluating hole-filling properties having four bottomed holes each 4 mm in diameter and 120 μm deep.

[0133] One release film was removed from each of the pressure-sensitive adhesive sheet laminates prepared in the Examples and Comparative Examples, and the exposed adhesive surface was roll-pressed onto a soda-lime glass sheet (82 mm × 54 mm × 0.55 mm thick). The remaining release film was then removed, and the exposed adhesive surface was placed opposite the surface of the substrate for evaluating hole-filling properties, and the substrate was press-laminated under reduced pressure (2 kPa absolute pressure) using a vacuum laminator. Heat and pressure treatment was performed in an autoclave (65°C, 0.45 MPa gauge pressure, 20 minutes) to prepare a laminate for evaluating hole-filling properties.

[0134] The laminate was visually observed, and those in which voids of 1 mm or more in diameter were found inside one or more bottomed holes were rated as "poor," and others were rated as "good." When the voids were non-spherical, the diameter of the voids was determined as the longest diameter.

[0135] <Reliability (anti-foaming reliability)> Bottomed holes with a diameter of 4 mm were made in the four corners of an 87 μm thick polarizing plate (70 mm×150 mm) with an adhesive layer, with the distance from the edge to the center of the hole being 6 mm. The film was roll-attached to a soda lime glass plate measuring 75 mm×155 mm and 0.55 mm thick to prepare a substrate for reliability evaluation having four bottomed holes each having a diameter of 4 mm and a depth of 87 μm.

[0136] One release film was peeled off from each of the pressure-sensitive adhesive sheet laminates prepared in the Examples and Comparative Examples, and the exposed adhesive surface was roll-pressed onto a soda-lime glass (75 mm × 155 mm × 0.55 mm thick). The remaining release film was then peeled off, and the exposed adhesive surface was placed opposite the surface of the reliability evaluation substrate having the bottomed holes, and the two were press-laminated under reduced pressure (2 kPa absolute pressure) using a vacuum laminator. After heating and pressurizing in an autoclave (65°C, gauge pressure 0.45 MPa, 20 minutes), ultraviolet light of 365 nm was irradiated through soda lime glass at an integrated light intensity of 4000 mJ / cm. 2 The adhesive sheet was cured by irradiation so as to obtain a sample for reliability evaluation. However, for the adhesive sheet 8 of Example 8 and the adhesive sheet 11 of Example 11, ultraviolet light was irradiated through soda lime glass at 365 nm with an integrated light intensity of 4000 mJ / cm 2 2 instead of 3000mJ / cm 2 The adhesive sheet was cured by irradiation so as to obtain a sample for reliability evaluation.

[0137] This reliability evaluation sample was placed in a heat cycle tester and subjected to 100 high-temperature and low-temperature cycles (high temperature: 80°C, low temperature: -40°C, exposure time: 30 minutes at each temperature, temperature change rate: within 5 minutes) before being stored.

[0138] The reliability evaluation samples were visually inspected after storage, and samples with no bubbles found in the holes were judged as "good," samples with one bubble less than 500 μm in diameter found in the holes were judged as "fair," and samples with one bubble 500 μm or more in diameter found in the holes or two or more bubbles found in the holes were judged as "poor." When the bubble was non-spherical, the diameter of the bubble was determined as the longest diameter.

[0139] <Storability> The adhesive sheets of the adhesive sheet laminates produced in the Examples and Comparative Examples were cut into half-cut pieces of 30 mm x 30 mm squares and stored in a 40°C environment for 200 hours. For each side of the adhesive sheet, the maximum amount of adhesive protrusion from the half-cut marking was measured, and the average value of the four sides was taken as the adhesive protrusion distance (mm). Adhesive protrusion distances of less than 0.2 mm were rated as "good," and those of 0.2 mm or more were rated as "poor."

[0140] [Table 1]

[0141] From the above examples and the results of the tests conducted by the present inventors, it has been found that, if a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive resin composition containing a (meth)acrylic polymer (A) has a predetermined creep strain before and after curing, it can be hot-melted by heat and pressure treatment, and can exhibit excellent fluidity. Therefore, the hot-melted pressure-sensitive adhesive resin composition can be applied to the pores present on the surface (adhesion surface) of the adherend, for example, the depth (mm) / base area (mm 2 ) is 1.0 × 10 -5 ~3.0×10 -1 It was found that the adhesive agent could flow into the bottomed holes, filling every corner without leaving any voids. Furthermore, it was found that after the adhesive sheet hardened, even if the adherend changed in size, the adhesive agent filled inside the holes could be prevented from foaming.

[0142] In Comparative Example 1, the creep strain after 180 seconds at 80°C after curing was less than 10%, and foaming occurred from the adhesive, making it unsuitable for practical use. This foaming is thought to be caused by dimensional changes in the adherend during storage after curing. In Comparative Example 2, the creep strain after 1200 seconds at 50°C before curing was 1500% or more, and when stored in the form of a pressure-sensitive adhesive sheet laminate, there was a problem with adhesive extrusion. In Comparative Example 3, the creep strain after 1200 seconds at 50°C before hardening was 150% or less, and when poured into a bottomed hole, it was not able to fill every corner, and voids were observed in the bottomed hole, making it unsuitable for practical use.

Claims

1. a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive resin composition comprising a (meth)acrylic polymer (A) as a main component resin, a reactive diluent (B), and an initiator (C), wherein the reactive diluent (B) contains a polyfunctional (meth)acrylate component (b-1) having two or more (meth)acryloyl groups in an amount of 0.5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the (meth)acrylic polymer (A); An active energy ray-curable adhesive sheet having a thickness of 0.8 to 1.5 mm, in which the creep strain after 1200 seconds at 50°C before curing is 150% or more and less than 1500%, and the creep strain after 180 seconds at 80°C after curing under the following curing conditions is 10% or more. Curing conditions: 3000 to 4000 mJ / cm with 365 nm ultraviolet light ２ The resin is cured by irradiating it with an integrated amount of light within the range.

2. The active energy ray-curable adhesive sheet according to claim 1, wherein the reactive diluent (B) comprises a polyfunctional (meth)acrylate component (b-1) having two or more (meth)acryloyl groups and a monofunctional (meth)acrylate component (b-2) having one (meth)acryloyl group.

3. The active energy ray-curable adhesive sheet according to claim 2, wherein the polyfunctional (meth)acrylate component (b-1) is a component having a glass transition temperature of higher than 0°C when made into a homopolymer, and the monofunctional (meth)acrylate component (b-2) is a component having a glass transition temperature of 0°C or lower when made into a homopolymer.

4. The active energy ray-curable adhesive sheet according to claim 2 or 3, wherein the content mass ratio of the polyfunctional (meth)acrylate component (b-1) to the monofunctional (meth)acrylate component (b-2) is (b-1):(b-2) = 1:0.1 to 1:

9.

5. 5. The active energy ray-curable adhesive sheet according to claim 1, wherein the content of the reactive diluent (B) is 0.2 parts by mass or more and 30 parts by mass or less relative to 100 parts by mass of the (meth)acrylic polymer (A).

6. The active energy ray-curable adhesive sheet according to any one of claims 1 to 5, which has a multi-layer structure of two or more layers.

7. The active energy ray-curable adhesive sheet according to any one of claims 1 to 6, wherein the adhesive resin composition further contains a silane coupling agent (D).

8. The active energy ray-curable adhesive sheet according to any one of claims 1 to 7, wherein the (meth)acrylic polymer (A) is a block copolymer and / or a copolymer containing a structural unit derived from a macromonomer as a branch component.

9. The active energy ray-curable adhesive sheet according to any one of claims 1 to 7, wherein the (meth)acrylic polymer (A) is a copolymer containing a structural unit derived from a macromonomer as a branch component, and the copolymerization ratio of the macromonomer is 10 mass% or less.

10. The active energy ray-curable adhesive sheet according to any one of claims 1 to 9, wherein the adhesive resin composition contains a hydrocarbon tackifier.

11. A pressure-sensitive adhesive sheet laminate with a release film, comprising the active energy ray-curable pressure-sensitive adhesive sheet according to any one of claims 1 to 10 and a release film laminated together.

12. A pressure-sensitive adhesive sheet obtained by curing the active energy ray-curable pressure-sensitive adhesive sheet according to any one of claims 1 to 10.

13. A laminate for constituting an image display device, having a configuration in which two image display device components are laminated via an adhesive sheet, the pressure-sensitive adhesive sheet comprises a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive resin composition comprising a (meth)acrylic polymer (A) as a main component resin, a reactive diluent (B), and an initiator (C), wherein the reactive diluent (B) comprises a polyfunctional (meth)acrylate component (b-1) having two or more (meth)acryloyl groups in an amount of 0.5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the (meth)acrylic polymer (A); the pressure-sensitive adhesive sheet has a thickness of 0.8 to 1.5 mm, and exhibits a creep strain of 150% or more and less than 1500% at 50°C for 1200 seconds before curing, and exhibits a creep strain of 10% or more at 80°C for 180 seconds after curing under the following curing conditions: At least one of the components of the image display device has a depth (mm) / base area (mm ２ ) is 1.0 × 10 －５ ~3.0 x 10 －１ 1. A laminate for use in an image display device, comprising: a bottomed hole; Curing conditions: 3000 to 4000 mJ / cm with 365 nm ultraviolet light ２ The resin is cured by irradiating it with an integrated amount of light within the range.

14. A laminate for constituting an image display device, comprising two image display device constituent members laminated together via a pressure-sensitive adhesive sheet having a thickness of 0.8 to 1.5 mm, and having a creep strain of 10% or more after curing at 80°C for 180 seconds under the following curing conditions: The cured pressure-sensitive adhesive sheet is a cured pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive resin composition comprising a (meth)acrylic polymer (A) as a main component resin, a reactive diluent (B), and an initiator (C), wherein the reactive diluent (B) comprises a polyfunctional (meth)acrylate component (b-1) having two or more (meth)acryloyl groups in an amount of 0.5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the (meth)acrylic polymer (A), At least one of the components of the image display device has a depth (mm) / base area (mm ２ ) is 1.0 x 10 －５ ~3.0 x 10 －１ and the cured pressure-sensitive adhesive sheet is filled into the bottomed holes in a state in which no voids having a diameter of 1 mm or more exist. Curing conditions: 3000 to 4000 mJ / cm with 365 nm ultraviolet light ２ The resin is cured by irradiating it with an integrated amount of light within the range.

15. The laminate for use in constituting an image display device according to claim 14, wherein the pressure-sensitive adhesive sheet after curing has a multi-layer structure of two or more layers.

16. The image display device constituent member is a laminate comprising any one or a combination of two or more selected from the group consisting of a touch panel, an image display panel, a surface protection panel, a polarizing film, and a retardation film, according to any one of claims 13 to 15. The laminate for constituting an image display device according to any one of claims 13 to 15.

17. An image display device constructed using the laminate for constituting an image display device according to any one of claims 13 to 16.

18. A method for producing a laminate for constituting an image display device, comprising: two image display device constituent members laminated together via a cured active energy ray-curable adhesive sheet according to any one of claims 1 to 10; The pressure-sensitive adhesive sheet is bonded to one surface of a first image display device component to form a bonded body, a surface to be bonded of a second image display device component having a bottomed hole on the surface to be bonded and a pressure-sensitive adhesive sheet of the bonded body are brought into face-to-face contact with each other under reduced pressure to form a laminate; a pressure-sensitive adhesive resin composition is allowed to flow into the bottomed hole of the second image display device component by subjecting the laminate to a heating and pressurizing treatment to hot-melt the pressure-sensitive adhesive sheet; A method for producing a laminate for use in constructing an image display device, comprising irradiating the pressure-sensitive adhesive sheet sandwiched between first and second image display components with active energy rays to cure the pressure-sensitive adhesive sheet.

19. The bottomed hole of the second image display device component has a depth (mm) / bottom area (mm ２ ) is 1.0 x 10 －５ ~3.0 x 10 －１ 19. The method for producing a laminate for constituting an image display according to claim 18, wherein

20. The method for producing a laminate for constituting an image display device according to claim 18 or 19, wherein the adhesive sheet after curing has a thickness of 0.8 to 1.5 mm and exhibits a creep strain of 10% or more after 180 seconds at 80°C.

21. A method for manufacturing a laminate for constructing an image display according to any one of claims 18 to 20, characterized in that the heat and pressure treatment on the laminate is performed at a temperature of 50°C or higher and 80°C or lower, and a pressure of 0.2 MPa or higher and 0.8 MPa or lower is applied to the laminate.

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