Active energy ray-curable adhesive sheet, adhesive sheet laminate with release film, adhesive sheet, laminate for constituting image display device, and image display device

Abstract

An adhesive sheet curable by active energy rays that does not readily soften or swell even when penetrated by an oily component such as sebum, that moreover can exhibit exceptional fluidity when affixed to an adherend, and that furthermore can exhibit reliable foaming resistance after having been laminated on an adherend and cured. Proposed by the present invention as said adhesive sheet is an adhesive sheet curable by active energy rays that comprises an adhesive agent layer containing a (meth)acrylic polymer (A) and that satisfies requirements (1) and (2).　(1) The thickness is 0.8-1.5 m, and the strain (creep strain) after a pressure of 1,000 Pa has been applied for 1,200 seconds at a temperature of 50°C is 150-1,500%.　(2) The oil and fat swelling rate derived according to formula (i) is 30% or less, where So is the initial surface area of the adhesive sheet, and St is the surface area after the adhesive sheet has been immersed in an artificial sebum liquid (a mixture in which squalene / oleic acid = 1 / 1) for four days at 25°C.　Formula (i): (Oil and fat swelling rate (%))=(St−So) / So×100

Description

[Technical Field]

[0001] The present invention relates to an active energy ray-curable pressure-sensitive adhesive sheet that has the property of being cured by active energy rays, a pressure-sensitive adhesive sheet laminate with a release film that uses the same, a pressure-sensitive adhesive sheet, a laminate for constituting an image display device, and 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 pressure-sensitive adhesive composition containing an ultraviolet-curable resin is filled into the gap, and then the liquid adhesive composition is cured by irradiating it 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 a pressure-sensitive adhesive sheet containing a pressure-sensitive adhesive 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 pressure-sensitive adhesive 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.

[0007] Furthermore, in recent years, the following problems have arisen when using laptops, tablets, and smartphones. Specifically, there are many opportunities for people's fingers and other objects to come into contact with the housing or image display screen, and in addition to sweat, oily components such as sebum and cosmetics are present on the surface of the skin. Over long periods of use, these components can gradually seep in, for example, from the edge of the joint between the protective panel and the housing, and may even penetrate into the adhesive layer of the double-sided adhesive tape. Furthermore, because oily components have the effect of softening and swelling the adhesive, problems such as the adhesive composition of the adhesive sheet spilling over the edge of the adherend occur.

[0008] To address this problem, Patent Document 5 discloses an oil-resistant double-sided pressure-sensitive adhesive tape in which the pressure-sensitive adhesive is resistant to softening and swelling even when penetrated by oily components such as sebum. The pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive tape is made of an acrylic pressure-sensitive adhesive composition containing an acrylic copolymer having, as monomer components, n-butyl acrylate and a vinyl monomer having a polar group, and the content of n-butyl acrylate in the monomer components forming the acrylic copolymer is 70 mass % or more. [Prior art documents] [Patent documents]

[0009] [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 [Patent Document 5] Japanese Patent Application Laid-Open No. 2009-215355 Summary of the Invention [Problem to be solved by the invention]

[0010] In the above Patent Documents 1 to 4, it is possible to fill gaps between components that constitute an image display device (also referred to as "image display device components") and obtain step absorption properties, but there is a demand for step absorption properties for image display device components that have even greater unevenness. That is, the surfaces of components of image display devices may be uneven due to wiring, printing, pattern development, etching, hole-punching, surface treatment, etc. In recent years, there has been a trend in designs for image display devices such as mobile phones in which almost the entire area of ​​the image display panel is used as a display, and as a result, cameras have come to be placed within the display area. To place a camera within the display, holes are formed in functional layers such as polarizing films and reflective films laminated on the surface of the image display panel in accordance with the position and size of the camera. Pressure-sensitive adhesive sheets for bonding image display device components having such holes are required to have the property of allowing the pressure-sensitive adhesive to flow into the holes and fill every corner (high fluidity). Furthermore, the above Patent Documents 1 to 4 do not improve the penetration of oily components such as sebum, and are insufficient in achieving both high fluidity and oil resistance. Furthermore, although Patent Document 5 has some oil resistance, it is still not satisfactory in terms of compatibility with high fluidity. An adhesive sheet for bonding components of an image display device having such stepped portions must be able to conform to the unevenness and fill every corner, otherwise air bubbles will form inside the adhesive layer and distortion or deformation will occur in the components of the image display device. Therefore, the adhesive sheet is required to have high fluidity. However, it has been difficult to achieve high fluidity during lamination while suppressing softening and swelling due to penetration of oily components.

[0011] Therefore, the present invention provides an active energy ray-curable adhesive sheet that has such excellent oil resistance that it does not soften or swell and protrude beyond the edge of an adherend even when penetrated by oily components such as sebum, and that can flow into and absorb unevenness even if the adherend has unevenness in the adherend surface, such as bottomed holes, and also provides a laminate for use in constituting an image display device and an image display device that use the same. [Means for solving the problem]

[0012] The present invention proposes an active energy ray-curable pressure-sensitive adhesive sheet that includes a pressure-sensitive adhesive layer containing a (meth)acrylic polymer (A) and satisfies the following requirements (1) and (2). (1) The thickness is 0.8 to 1.5 mm, and the strain (creep strain) after applying a pressure of 1000 Pa at a temperature of 50°C for 1200 seconds is 150% or more and 1500% or less. (2) When the initial area of ​​the adhesive sheet is So and the area of ​​the adhesive sheet after immersion in an artificial sebum liquid (a 1:1 mixture of squalene and oleic acid) at 25°C for 4 days is St, the oil swelling rate calculated by the following formula (i) is 30% or less. Oil swelling rate (%) = [(St-So) / So] × 100 (i)

[0013] The present invention also proposes a pressure-sensitive adhesive sheet laminate with a release film, which has a configuration in which the active energy ray-curable pressure-sensitive adhesive sheet proposed by the present invention and a release film are laminated together.

[0014] The present invention also provides a laminate for constituting an image display device, which has a configuration in which two image display device constituent members are laminated via an active energy ray-curable pressure-sensitive adhesive sheet having an oil swelling ratio calculated by the following formula (i) of 30% or less, The present invention proposes a laminate for use in constituting an image display device, in which the pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive resin composition containing a (meth)acrylic polymer (A), has a thickness of 0.8 to 1.5 mm, and exhibits a strain (creep strain) of 150% or more and 1500% or less after application of a pressure of 1000 Pa at a temperature of 50°C for 1200 seconds. Oil swelling rate (%) = [(St-So) / So] × 100 (i) In formula (i), So is the initial area of ​​the adhesive sheet, and St is the area after the adhesive sheet has been immersed in an artificial sebum liquid (a 1:1 mixture of squalene and oleic acid) at 25°C for 4 days.

[0015] The present invention also provides a laminate for constituting an image display device, comprising two image display device constituent members laminated together via a cured adhesive sheet obtained by curing an active energy ray-curable adhesive sheet having an oil swelling ratio of 30% or less as determined by the following formula (i): The present invention proposes a laminate for use in constituting an image display device, wherein the pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer (A), has a thickness of 0.8 to 1.5 mm, and exhibits a distortion (creep strain) of 5% or more and 220% or less after application of a pressure of 1000 Pa at a temperature of 80°C for 180 seconds. Oil swelling rate (%) = [(St-So) / So] × 100 (i) In formula (i), So is the initial area of ​​the adhesive sheet, and St is the area after the adhesive sheet has been immersed in an artificial sebum liquid (a 1:1 mixture of squalene and oleic acid) at 25°C for 4 days.

[0016] The present invention also proposes an image display device constructed using the laminate for constituting an image display device. [Effects of the Invention]

[0017] The active energy ray-curable adhesive sheet proposed by the present invention has excellent oil resistance, and even when penetrated by oily components such as sebum, it does not soften or swell and does not protrude from the edge of the adherend. Furthermore, the active energy ray-curable adhesive sheet proposed by the present invention can exhibit excellent fluidity when heated and is attached to an adherend, and even if the adherend surface has irregularities, such as bottomed holes, the adhesive can flow into the irregularities and absorb the irregularities. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will now be described based on embodiments, although the present invention is not limited to the embodiments described below.

[0019] <This adhesive sheet> An adhesive sheet according to one embodiment of the present invention (referred to as "the adhesive sheet") is an energy ray-curable adhesive sheet having an adhesive layer (referred to as "the adhesive layer") containing a (meth)acrylic polymer (A) as a main component resin.

[0020] <Present adhesive layer> The pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet can be formed from a pressure-sensitive adhesive composition (referred to as the "pressure-sensitive adhesive composition") that contains, for example, a (meth)acrylic polymer (A), and optionally a crosslinking agent (B) and / or a polymerization initiator (C), and optionally other components. The pressure-sensitive adhesive composition preferably contains the (meth)acrylic polymer (A) as a main component resin.

[0021] 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, the adhesive sheet can be cured (also referred to as "full curing") with active energy rays before or after being attached to an adherend, thereby increasing the cohesive strength and improving the adhesiveness.

[0022] The "main component resin" refers to the resin with the highest mass percentage among the resins constituting the present pressure-sensitive adhesive layer or the present pressure-sensitive adhesive composition. The content of the main component resin may account for 50 mass% or more, particularly 60 mass% or more, 70 mass% or more, or 75 mass% or more (including 100 mass%) of the resins constituting the present pressure-sensitive adhesive layer or the present pressure-sensitive adhesive composition.

[0023] (gel fraction) Before being cured by active energy rays, the present pressure-sensitive adhesive sheet is in a non-crosslinked or slightly crosslinked state, that is, in a state in which the gel fraction is 0% or more and 20% or less. From the viewpoint of conformability to irregularities on the adherend surface, the gel fraction is preferably 10% or less, more preferably 8% or less, and even more preferably 5% or less.

[0024] In addition, this adhesive sheet can emit active energy rays with a wavelength of 365 nm at an integrated light intensity of 4000 mJ / cm 2 When the composition is cured by irradiation, the gel fraction increases compared to before curing, and the gel fraction is preferably 10% or more and 80% or less. By ensuring that the gel fraction is 10% or more after curing with active energy rays, it is possible to provide the pressure-sensitive adhesive sheet with shape stability, and when formed into a laminate, shape stability and durability can be imparted. From this perspective, the gel fraction after curing with active energy rays is preferably 10% or more, more preferably 30% or more, even more preferably 40% or more, and even more preferably 50% or more. On the other hand, the gel fraction after curing with active energy rays is preferably 80% or less. A gel fraction of 80% or less allows the laminate for constituting an image display device to have appropriate flexibility even after curing with active energy rays, and can follow dimensional changes in components for the image display device without foaming when stored in high or low temperature environments. From this perspective, a gel fraction of 75% or less is more preferable, and of these, a gel fraction of 70% or less is even more preferable.

[0025] In order to adjust the gel fraction after curing of the present pressure-sensitive adhesive sheet to fall within the above range, it is preferable to adjust the composition or molecular weight of the (meth)acrylic polymer (A) as the base polymer, adjust the amount of crosslinking agent (B) added, or adjust the intensity or integrated light amount of the active energy rays to be irradiated, although this is not a limitation.

[0026] <Layer structure> 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.

[0027] <Thickness> The thickness of the present 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.

[0028] 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.

[0029] <Creep properties> The pressure-sensitive adhesive sheet preferably has a thickness of 0.8 to 1.5 mm, and exhibits a distortion (creep distortion) of 150% or more and 1500% or less after application of a pressure of 1000 Pa at a temperature of 50° C. for 1200 seconds. In the present pressure-sensitive adhesive sheet, the creep strain at 50°C of 150% or more indicates that the sheet is easily deformed in a heated state, which is preferable in that the pressure-sensitive adhesive resin can flow and fill uneven portions such as bottomed holes upon heating. From this perspective, the strain is more preferably 160% or more, more preferably 180% or more, and even more preferably 200% or more. On the other hand, if the creep strain at 50°C is 1500% or less, it is preferable from the viewpoint of excellent dimensional stability of the PSA sheet. From this viewpoint, the strain is more preferably 1400% or less, of which 1300% or less, and of which 1200% or less is even more preferable.

[0030] 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.

[0031] The above-mentioned "thickness of 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 fall within this range by stacking several sheets, etc. The same applies when the thickness of the measurement sample is specified in other tests.

[0032] In the present pressure-sensitive adhesive sheet, the creep strain can be adjusted to the above range preferably by adjusting the composition or molecular weight of the (meth)acrylic polymer (A) which is the base polymer described below, or by adjusting the amount of crosslinking agent (B) added, although this is not limitative.

[0033] In addition, this adhesive sheet can emit active energy rays with a wavelength of 365 nm at an integrated light intensity of 4000 mJ / cm 2 When cured by irradiation, the adhesive sheet after curing preferably has a thickness of 0.8 to 1.5 mm and exhibits a distortion (creep distortion) of 5% to 220% after application of a pressure of 1000 Pa at a temperature of 80°C for 180 seconds. In this adhesive sheet, the distortion (creep distortion) after application of a pressure of 1000 Pa for 180 seconds at a temperature of 80°C after curing is 5% or more, which indicates that the sheet is easily deformed at high temperatures even after curing and has excellent stress relaxation properties.Therefore, even if the dimensions of the adherend change due to temperature changes after being attached to the adherend, the sheet can follow the change without causing foaming or peeling at the interface with the adherend, which is preferable in that it provides excellent durability. From this viewpoint, the creep strain after curing with active energy rays is more preferably 7% or more, more preferably 10% or more, and even more preferably 15% or more. On the other hand, if the upper limit of the strain (creep strain) after curing is too high, there is a risk that the adhesive sheet will protrude from the end face of the laminate in a high temperature environment, causing the end face to become sticky. Therefore, the creep strain after curing with active energy rays is preferably 220% or less, more preferably 100% or less, even more preferably 80% or less, and even more preferably 60% or less, 40% or less, or 30% or less. By setting the upper limit of the strain (creep strain) after curing to 80% or less, durability in high-temperature and low-temperature environments can be achieved, and the adhesive extrusion at the edges of the pressure-sensitive adhesive sheet and the occurrence of in-plane bubbles can be suppressed. From this perspective, the upper limit is preferably 70% or less, more preferably 60% or less, even more preferably 40% or less, and particularly preferably 30% or less.

[0034] As described above, the creep strain of the adhesive sheet after curing with active energy rays was measured after adjusting the thickness of the adhesive sheet to 0.8 mm to 1.5 mm. However, as described above, this was done to take into account the influence of the measuring tool, and it is not intended that the thickness of the adhesive sheet must be within the above range.

[0035] In order to adjust the creep strain of the present pressure-sensitive adhesive sheet after curing with active energy rays to fall within the above range, it is preferable to adjust the composition or molecular weight of the (meth)acrylic polymer (A) which is the main component resin, adjust the type or amount of the crosslinking agent (B) added, or adjust the dose of active energy rays, although this is not limitative.

[0036] <Oil swelling rate> The pressure-sensitive adhesive sheet preferably has an oil swelling rate of 30% or less, as calculated by the following formula (i), where So is its initial area and St is the area of ​​the pressure-sensitive adhesive sheet after immersion in an artificial sebum liquid (a 1:1 mixture of squalene and oleic acid) at 25°C for 4 days. Oil swelling rate (%) = [(St-So) / So] × 100 (i)

[0037] The pressure-sensitive adhesive sheet used for measuring the oil swelling ratio may have any shape. As a method for measuring the area, for example, if the pressure-sensitive adhesive sheet is polygonal or circular, the area can be calculated from the perimeter dimensions, etc. Alternatively, the area can be determined by subjecting the pressure-sensitive adhesive sheet to be measured to image processing and analysis, etc.

[0038] If the oil swelling ratio of the present pressure-sensitive adhesive sheet is 30% or less, it is unlikely to soften or swell even when oily components such as sebum penetrate into it, and it is possible to exhibit excellent oil resistance. From this viewpoint, the oil swelling ratio of the present pressure-sensitive adhesive sheet is more preferably 25% or less, even more preferably 20% or less, even more preferably 15% or less, even more preferably 10% or less.

[0039] In addition, this adhesive sheet can emit active energy rays with a wavelength of 365 nm at an integrated light intensity of 4000 mJ / cm2 When irradiated and cured, the oil swelling rate after curing is preferably 30% or less. If the oil swelling rate after curing is 30% or less, even if oily components such as sebum penetrate, the film is unlikely to soften or swell, and excellent oil resistance can be exhibited. From this viewpoint, the oil swelling ratio of the present pressure-sensitive adhesive sheet after curing is preferably 30% or less, more preferably 28% or less, and even more preferably 25% or less.

[0040] In the present pressure-sensitive adhesive sheet, the oil swelling ratio can be adjusted to the above range by, for example, adjusting the composition of the (meth)acrylic polymer (A) which is the base polymer described below, for example, the composition ratio of a vinyl monomer having a polar group to an alkyl (meth)acrylate such as butyl acrylate, in which the number of carbon atoms in the alkyl group is relatively short (for example, 6 or less), adjusting the structure or amount of the crosslinking agent (B) added, or adjusting the amount of active energy ray irradiation, etc. However, the method is not limited to these.

[0041] <Adhesive strength> The adhesive strength of the adhesive sheet to soda-lime glass, i.e., when the adhesive sheet is roll-pressed onto soda-lime glass by rolling it back and forth once, and then cured at 60°C for 30 minutes, the adhesive sheet is peeled off from the soda-lime glass at 23°C, 40% RH, with a peel angle of 180° and a peel rate of 60 mm / min, and the 180° peel force to the glass is preferably 2 N / cm or more. If the peel strength is 2 N / cm, it becomes easy to position and temporarily fix the image display device components (described later) when they are bonded together, and it also has the effect of suppressing the penetration of oily components such as sebum. From this viewpoint, the 180° peel strength is preferably 2 N / cm or more, more preferably 4 N / cm or more, even more preferably 5 N or more, and even more preferably 10 N / cm or more. There is no particular upper limit to the peel strength, but it is usually 20 N / cm.

[0042] The adhesive strength of this pressure-sensitive adhesive sheet when it is stuck to soda-lime glass and then cured is measured. In other words, the pressure-sensitive adhesive sheet is roll-pressed onto soda-lime glass by rolling it back and forth once, and after curing at 60°C for 30 minutes, it is exposed to an active energy ray with a wavelength of 365 nm at an integrated light intensity of 4000 mJ / cm. 2 The adhesive sheet is cured by irradiating the sheet with light so that the temperature is such that the adhesive sheet hardens, and after aging at 23°C for 15 hours, the adhesive sheet is peeled from the soda lime glass at 23°C, 40% RH, a peel angle of 180°, and a peel rate of 60 mm / min, and the 180° peel force against the glass is preferably 2 N / cm or more. If the peeling force is 2 N / cm, when the laminate is bonded to a component of an image display device described later, penetration of oily components such as sebum is suppressed and durability is improved, which is preferable. From this viewpoint, the peel strength when irradiated with active energy rays after being bonded to soda lime glass is preferably 2 N / cm or more, more preferably 3 N / cm or more, even more preferably 5 N / cm or more, and even more preferably 10 N / cm or more. The upper limit of the peel strength is not particularly limited, but is usually 20 N / cm.

[0043] <Present Pressure-Sensitive Adhesive Composition> The present pressure-sensitive adhesive composition is a composition that contains, in addition to the (meth)acrylic polymer (A), preferably a crosslinking agent (B) and / or a polymerization initiator (C), and further, if necessary, a silane coupling agent (D) and other components.

[0044] ((Meth)acrylic polymer (A)) The pressure-sensitive adhesive composition contains a (meth)acrylic polymer (A), particularly as a main component resin. That is, it is the resin with the highest mass proportion among the resins constituting the pressure-sensitive adhesive composition. In this case, the mass proportion of the (meth)acrylic polymer (A) among the resins constituting the pressure-sensitive adhesive 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%).

[0045] The (meth)acrylic polymer (A) preferably contains a structural unit derived from a compound 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 or an alicyclic hydrocarbon group having 1 to 18 carbon atoms), and is obtained by polymerizing a polymerization component containing 35 mass % or more of the monomer component.

[0046] Among these, the (meth)acrylic polymer (A) is more preferably one polymerized containing 40% by mass or more of the above-mentioned monomer components as polymerization components, more preferably one polymerized containing 50% by mass or more, and particularly preferably one polymerized containing 60% by mass or more of the above-mentioned monomer components as polymerization components.

[0047] 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.

[0048] TIFF0007740267000001.tif20150

[0049] Examples of the monomer represented by the formula 1 include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, 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, and isooctyl (meth)acrylate. Examples of suitable acrylates include acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, t-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.

[0050] Among these, from the viewpoint of imparting durability to oily components to the PSA, it is preferred to include alkyl (meth)acrylates having an alkyl group carbon number of 6 or less, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, 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, and cyclohexyl (meth)acrylate, and particularly methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, and i-propyl (meth)acrylate. More preferably, the acrylate contains an alkyl (meth)acrylate having 5 or less carbon atoms in the alkyl group, such as ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, or neopentyl (meth)acrylate, and even more preferably, it contains an alkyl (meth)acrylate having 2 or more but 4 carbon atoms in the alkyl group, such as ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, or t-butyl (meth)acrylate, and among these, n-butyl (meth)acrylate is preferred.

[0051] The (meth)acrylic polymer (A) is preferably a copolymer having, as a copolymerization component, "another copolymerizable monomer" other than the above-mentioned monomer components.

[0052] The "other copolymerizable monomer" is preferably contained in the (meth)acrylic polymer (A) in an amount of 1 to 60% by mass, more preferably 2% by mass or more or 50% by mass or less, and even more preferably 3% by mass or more or 40% by mass or less.

[0053] Examples of the "other copolymerizable monomers" include (a) carboxyl group-containing monomers (hereinafter also referred to as "copolymerizable monomer a1"), (b) hydroxyl group-containing monomers (hereinafter also referred to as "copolymerizable monomer a2"), (c) amino group-containing monomers (hereinafter also referred to as "copolymerizable monomer a3"), (d) epoxy group-containing monomers (hereinafter also referred to as "copolymerizable monomer a4"), (e) amide group-containing monomers (hereinafter also referred to as "copolymerizable monomer a5"), (f) vinyl monomers (hereinafter also referred to as "copolymerizable monomer a6"), (g) macromonomers (hereinafter also referred to as "copolymerizable monomer a7"), (h) aromatic group-containing monomers (hereinafter also referred to as "copolymerizable monomer a8"), and (i) other functional group-containing monomers (hereinafter also referred to as "copolymerizable monomer a9"). These may be used alone or in combination of two or more.

[0054] 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.

[0055] Examples of the copolymerizable monomer a2 include hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-1-methylethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycerin mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polyethylene glycol polypropylene glycol mono(meth)acrylate, polyethylene glycol polybutylene glycol mono(meth)acrylate, polypropylene glycol polybutylene glycol mono(meth)acrylate, and hydroxyphenyl (meth)acrylate. These may be used alone or in combination of two or more.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] The copolymerizable monomer a6 may be a compound having a vinyl group in the molecule. Examples of such compounds include functional monomers having a functional group such as an alkoxyl alkyl group, such as ethoxydiethylene glycol acrylate, methoxytriethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxydipropylene glycol acrylate, and methoxypolypropylene glycol acrylate; 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.

[0060] The macromonomer as the copolymerizable monomer a7 is a polymer monomer having a terminal radically polymerizable unsaturated 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.

[0061] By using the copolymerizable monomer a7, a macromonomer can be introduced as a branch component of the graft copolymer, and the (meth)acrylic acid ester copolymer can be made into a graft copolymer. For example, a (meth)acrylic polymer (A) can be obtained, which is a graft copolymer having a macromonomer as a branch component. Therefore, the properties of the graft copolymer can be changed by selecting and blending ratios of copolymerizable monomer a7 and other monomers. In particular, in the present invention, the copolymerization ratio of the macromonomer in the (meth)acrylic polymer (A) is preferably 10 parts by mass or less relative to 100 parts by mass of the copolymer in terms of imparting fluidity during hot melting, more preferably 3 parts by mass or more or 9 parts by mass or less, and particularly preferably 4 parts by mass or more or 8 parts by mass or less.

[0062] 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 in which the alkyl group has 1 to 18 carbon atoms, alicyclic (meth)acrylates, the copolymerizable monomers a1, a2, a6, and the copolymerizable monomer a8 described below, which can be used alone or in combination of two or more.

[0063] Examples of the copolymerizable monomer a8 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.

[0064] Examples of the copolymerizable monomer a9 include (meth)acrylic-modified silicones and fluorine-containing monomers such as 2-acryloyloxyethyl acid phosphate, 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.

[0065] From the viewpoints of metal corrosion prevention and yellowing resistance, 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.

[0066] From the viewpoint of imparting durability to oily components, adhesive strength, and cohesive strength to the PSA, the (meth)acrylic polymer (A) preferably contains a vinyl monomer having a polar group, and particularly preferably contains a hydroxyl group-containing monomer and / or a nitrogen atom-containing monomer. That is, the (meth)acrylic polymer (A) is particularly preferably one having the above-mentioned "copolymerizable monomer a2," "copolymerizable monomer a3," or "copolymerizable monomer a5," especially "copolymerizable monomer a2," as a copolymerization component.

[0067] The (meth)acrylic polymer (A) is preferably a block copolymer and / or a graft copolymer from the viewpoint of imparting hot-melt properties to the pressure-sensitive adhesive. 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, and among these, one containing a graft copolymer is preferred.

[0068] 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.

[0069] 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.

[0070] 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.]

[0071] When obtaining the (meth)acrylic copolymer (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, but are not limited to, 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 methacrylate, multi-branched stearyl acrylate, and multi-branched stearyl methacrylate.

[0072] Furthermore, at least one of the repeating units derived from a (meth)acrylic acid ester contained in the acrylic copolymer (A) preferably has a glass transition temperature of 5 to 140° C. Specifically, since this affects the hot melt temperature of the pressure-sensitive adhesive sheet, this glass transition temperature (Tg) is preferably 5 to 140° C., more preferably 30 to 130° C., and even more preferably 40° C. or higher or 120° C. or lower, and even more preferably 50° C. or higher or 110° 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 so that it becomes hot-melt at a predetermined temperature, for example, around 20 to 80°C.

[0073] Examples of (meth)acrylic acid esters constituting such repeating units include methyl (meth)acrylate, ethyl methacrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl methcrete, t-butyl (meth)acrylate, isobutyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, 1,4-cyclohexanedimethanol mono(meth)acrylate, tetrahydrofurfuryl methacrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, and the copolymerizable monomer a7.

[0074] 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.

[0075] Here, the block copolymer refers to a 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. It is preferable that some blocks of the block copolymer contain repeating units derived from a macromonomer. On the other hand, a graft copolymer is a copolymer containing a repeating unit derived from a (meth)acrylic acid ester as the backbone component, and depending on the method of introducing the branch components, it has a structure such as a comb polymer, brush polymer, star polymer, palm polymer, or dumbbell polymer. The graft copolymer preferably contains a repeating unit derived from a macromonomer as a branch component.

[0076] When the (meth)acrylic polymer (A) is a copolymer containing structural units derived from a macromonomer as described above, it preferably contains 3 to 10 parts by mass of the macromonomer per 100 parts by mass of the copolymer from the viewpoint of imparting hot-melt properties. A copolymerization ratio of 3 parts by mass or more of the macromonomer per 100 parts by mass of the copolymer is preferred from the viewpoint of suppressing excessive flow during storage or hot-melting, while a copolymerization ratio of 10 parts by mass or less is preferred from the viewpoint of imparting fluidity during hot-melting. From this viewpoint, the copolymerization ratio of the macromonomer is preferably 3 parts by mass or more, more preferably 4 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 9 parts by mass or less, even more preferably 8 parts by mass or less, and even more preferably less than 7 parts by mass.

[0077] The glass transition temperature of the repeating 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. When the (meth)acrylic polymer (A) is a block copolymer and / or a graft copolymer, the content of the copolymerization component having a glass transition temperature within the above range is, for the same reasons as above, preferably 3 parts by mass or more, more preferably 4 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic polymer (A), and on the other hand, preferably 10 parts by mass or less, more preferably 9 parts by mass or less, even more preferably 8 parts by mass or less, and even more preferably less than 7 parts by mass.

[0078] The (meth)acrylic polymer (A) preferably contains, as monomer components, an "alkyl (meth)acrylate having an alkyl group with 6 or less carbon atoms" and a "vinyl monomer having a polar group." In this case, the content of "alkyl (meth)acrylate having an alkyl group with 6 or less carbon atoms" in the monomer components forming the acrylic polymer (A) is preferably 40% by mass or more, and the content of "vinyl monomer having a polar group" is preferably 10% by mass or more. 40% by mass or less It is preferable that: To improve oil resistance, i.e., to suppress penetration of oily components and swelling caused by oily components, it is preferable to include a "vinyl monomer containing a polar group" as a monomer component forming the acrylic copolymer (A). On the other hand, as the number of polar groups in the (meth)acrylic polymer (A) increases, the cohesive strength of the PSA sheet increases, and hot-melt properties tend to decrease. Furthermore, the polar groups may react with each other or with other components due to heating, gradually causing gelation, which may impair the quality stability of the PSA sheet. Thus, it is difficult to achieve both oil resistance and hot-melt properties at a high level of quality. However, if the (meth)acrylic polymer (A) has such a composition, it is preferable because it is possible to suppress the penetration of oily components into the pressure-sensitive adhesive sheet and the swelling of the pressure-sensitive adhesive sheet due to the oily components while simultaneously achieving hot-melt properties. From this viewpoint, the content of "alkyl (meth)acrylate having an alkyl group with 6 or less carbon atoms" in the monomer components forming the (meth)acrylic polymer (A) is preferably 40% by mass or more, more preferably 90% by mass or less, and even more preferably 45% by mass or more or 85% by mass or less. The content of the "vinyl monomer having a polar group" is, relative to 100 parts by mass of the (meth)acrylic polymer (A). 10 It is particularly preferable that the amount is 40 parts by mass or more. Preferably, Of these, it is particularly preferable that the amount is 35 parts by mass or less, more particularly 30 parts by mass or less, and even more particularly 25 parts by mass or less.

[0079] (Crosslinking agent (B)) The crosslinking agent (B) is a compound or composition that can undergo a polymerization reaction or a crosslinking reaction through a radical reaction caused by active energy rays, and can bond with the (meth)acrylic polymer. The crosslinking agent (B) is a compound having two or more crosslinkable functional groups. By including the crosslinking agent (B) in the pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition forms a crosslinked structure, and the durability and oil resistance of the pressure-sensitive adhesive sheet can be improved.

[0080] The crosslinking agent (B) is preferably a polyfunctional (meth)acrylate having a cyclic structure, from the viewpoint of suppressing swelling due to oily components after the formation of a crosslinked structure.

[0081] The crosslinking agent (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 can be 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.

[0082] The pressure-sensitive adhesive composition contains a polyfunctional (meth)acrylate component (b-1) having two or more (meth)acryloyl groups as the crosslinking agent (B), which allows the pressure-sensitive adhesive 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 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, thereby 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 composition can deform accordingly.

[0083] From this viewpoint, it is preferable to contain a polyfunctional (meth)acrylate component (b-1) and a monofunctional (meth)acrylate component (b-2). In such a 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 sufficient conformity to the adherend can be achieved.

[0084] Also, When the crosslinking agent (B) is contained,The content by mass of the crosslinking agent (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). is 2 It is more preferable that the amount is 0 parts by mass or less. Also, When the crosslinking agent (B) is contained, 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, even more preferably 1.5 parts by mass or more, and even more preferably 6 parts by mass or more, per 100 parts by mass of the (meth)acrylic polymer (A), from the viewpoint of forming a crosslinked structure and imparting resistance to swelling by oily components and cohesive strength after curing. The upper limit is preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less.

[0085] 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.

[0086] 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 glycidyl ether di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, adamantanediol di(meth)acrylate, adamantane dimethanol di(meth)acrylate, and dicyclo Pentadiene di(meth)acrylate, adamantanetriol tri(meth)acrylate, adamantanetrimethanol tri(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, dioxane glycol di(meth)acrylate, spiroglycol di(meth)acrylate, fluorene 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 Acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(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,Examples of suitable (meth)acrylic monomers include ultraviolet-curable polyfunctional (meth)acrylic monomers such as di(meth)acrylate of ε-caprolactone adduct of hydroxypivalic acid neopen glycol, trimethylolpropane tri(meth)acrylate, trimethylolpropane polyethoxy tri(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.

[0087] Among these, from the viewpoint of preventing swelling due to oily components, tricyclodecane dimethanol di(meth)acrylate, adamantanediol di(meth)acrylate, adamantane dimethanol di(meth)acrylate, dicyclopentadiene di(meth)acrylate, adamantanetriol tri(meth)acrylate, adamantane trimethanol tri(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, dioxane glycol di(meth)acrylate, spiroglycol di(meth)acrylate, fluorene di(meth)acrylate, bisphenol A polyethoxydi(meth)acrylate, bisphenol A polypropoxydi(meth)acrylate, bisphenol F polyethoxydi(meth)acrylate, ε-caprolactone-modified tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, tris(acryloxyethyl) (Meth)acrylates having a cyclic structure such as cyclohexanediol di(meth)acrylate, cyclohexanediol di(meth)acrylate, dioxane glycol di(meth)acrylate, and spiroglycol di(meth)acrylate are preferred, and among these, those having an alicyclic structure or a heterocyclic structure, such as tricyclodecane dimethanol di(meth)acrylate, adamantanediol di(meth)acrylate, adamantane dimethanol di(meth)acrylate, and dicyclopentadiene di(meth)acrylate, are more preferred, and among these, those having an alicyclic structure, such as tricyclodecane dimethanol di(meth)acrylate, adamantanediol di(meth)acrylate, adamantane dimethanol di(meth)acrylate, and dicyclopentadiene di(meth)acrylate are even more preferred.

[0088] 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.

[0089] <Polymerization initiator (C)> The polymerization initiator (C) may be any compound that generates radicals when exposed to active energy rays. Polymerization 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 a hydrogen donor in the system and can transfer hydrogen from the hydrogen donor.

[0090] The polymerization 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.

[0091] 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.

[0092] 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.

[0093] The content of the polymerization 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).

[0094] <Silane coupling agent (D)> The silane coupling agent (D) can improve adhesiveness, particularly adhesive strength to glass materials.

[0095] 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.

[0096] 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, per 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.

[0097] <Other ingredients> As "other components" other than those described above, the present pressure-sensitive adhesive composition may contain, as needed, various additives such as a tackifying 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. If necessary, a reaction catalyst such as a tertiary amine compound, a quaternary ammonium compound, or a tin laurate compound may be appropriately contained.

[0098] (Block copolymer or graft copolymer) In order to impart hot-melt properties to the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive composition may contain a block copolymer and / or a graft copolymer as a polymer other than the (meth)acrylic polymer (A). These copolymers preferably have at least one rubbery segment and one glassy segment.

[0099] 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 together. 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.

[0100] 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 12 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.

[0101] 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.

[0102] 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.

[0103] (plasticizer) The present pressure-sensitive adhesive composition may contain a plasticizer in order to impart hot-melt properties to the present pressure-sensitive adhesive sheet.

[0104] 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.

[0105] 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.

[0106] The mass content of the plasticizer is not particularly limited, but is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, per 100 parts by mass of the (meth)acrylic polymer (A).

[0107] (hydrocarbon tackifier) The present pressure-sensitive adhesive composition may contain a hydrocarbon tackifier in order to impart hot-melt properties to the present pressure-sensitive 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. The hydrocarbon tackifier is preferably compatible with the pressure-sensitive adhesive composition.

[0108] The content by mass of the hydrocarbon tackifier is not particularly limited, but is preferably 0.1 to 40 parts by mass, more preferably 0.5 to 20 parts by mass, per 100 parts by mass of the (meth)acrylic polymer (A).

[0109] By including these plasticizers and hydrocarbon tackifiers, a hot-melt pressure-sensitive adhesive composition having adhesive properties can be suitably produced.

[0110] <Method for preparing the present pressure-sensitive adhesive composition> The present pressure-sensitive adhesive composition can be obtained by mixing, in addition to the (meth)acrylic polymer (A), preferably a crosslinking agent (B) and / or a polymerization initiator (C), and further, 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 composition. In this case, it is desirable to mix the components of the pressure-sensitive adhesive composition in advance and then perform the heat treatment. A master batch prepared by concentrating various mixed components may also be used.

[0111] 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 composition can be used as a solvent-free system, which does not contain a solvent. When used as a solvent-free system, no solvent remains, which has the advantage of improving heat resistance and light resistance.

[0112] <Layers other than the present adhesive layer> In the present invention, if the pressure-sensitive adhesive sheet has a multi-layer structure of two or more layers, this is preferred 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, the pressure-sensitive adhesive composition forming the layer other than the pressure-sensitive adhesive layer also preferably contains the (meth)acrylic polymer (A) as a main component resin, and in particular, it is preferable to contain 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 crosslinking agent (B) and the polymerization initiator (C).In this case, it is more preferable that the crosslinking agent (B) contains a polyfunctional (meth)acrylate component (b-1) and a monofunctional (meth)acrylate component (b-2).

[0113] <Method of producing and using the adhesive sheet> The present pressure-sensitive adhesive sheet can also be used as a stand-alone pressure-sensitive adhesive sheet. For example, the present pressure-sensitive adhesive sheet can be produced by directly applying the present pressure-sensitive adhesive composition to an adherend to form a sheet, or by directly extruding the present pressure-sensitive adhesive composition or injecting it into a mold. Furthermore, the present pressure-sensitive adhesive sheet can also be produced by directly filling the present pressure-sensitive adhesive composition between components such as conductive components.

[0114] On the other hand, the present PSA sheet can also be produced as a PSA sheet laminate with a release film, comprising a PSA layer formed from the present PSA composition and a release film. For example, the present PSA composition can be formed into a single-layer or multi-layer PSA sheet on a release film.

[0115] 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.

[0116] 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.

[0117] <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. By irradiating the adhesive sheet with active energy rays, the adhesive sheet of the present laminate is cured (the adhesive sheet after curing is referred to as the "cured adhesive sheet"), allowing two components for an image display device to be bonded together.

[0118] 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.

[0119] When at least one of the two image display device components has irregularities on the surface that comes into contact with the pressure-sensitive adhesive sheet, the ratio of 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 bottomed holes can be filled with the pressure-sensitive adhesive composition of the pressure-sensitive adhesive sheet, and the bottomed holes can be filled so that no voids with a diameter of at least 1 mm or more exist in the holes. Note that the "pore diameter" refers to the longest diameter in the case of non-spherical voids.

[0120] 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.

[0121] 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 surface protection panel, an image display panel, a polarizing film, a retardation film, etc. can be mentioned, however, the present invention is not limited to these lamination examples.

[0122] The touch panel may be of a resistive type, a capacitance type, an electromagnetic induction type, etc. Among these, the capacitance type is preferred.

[0123] The material of the protective panel may be glass, or may be 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 polyimide resin, a phenolic resin, a melamine resin, or an epoxy resin.

[0124] 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 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.

[0125] 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.

[0126] <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.

[0127] This laminate is formed by laminating this adhesive sheet to one side of a first image display device component to form a laminate, and then laminating the adhesive sheet of the laminate to the surface to be laminated of a second image display device component, with the adhesive sheet of the laminate facing the surface to be laminated. As the lamination method, known methods such as roll lamination, press lamination using parallel flat plates, and diaphragm lamination can be used. The lamination environment includes an atmospheric lamination method in which lamination is performed under normal pressure and a vacuum lamination method in which lamination is performed under reduced pressure. From the viewpoint of preventing air bubbles during lamination, a lamination method using parallel flat plates under a reduced pressure environment is preferred.

[0128] Next, the laminate is heated to hot-melt the pressure-sensitive adhesive sheet. That is, the laminate is heated to 40°C or higher and 80°C or lower to hot-melt the pressure-sensitive adhesive sheet, while the pressure-sensitive adhesive composition is allowed to blend into the surface of the adherend. If the second image display device component has uneven portions, the pressure-sensitive adhesive composition is allowed to flow into the uneven portions. The heating temperature at this time is preferably 40°C or higher and 80°C or lower, more preferably 45°C or higher or 75°C or lower, and even more preferably 50°C or higher or 70°C or lower. Additionally, a pressure treatment may be carried out in conjunction with the heat treatment, and the laminate may be subjected to an air pressure of 0.2 MPa to 0.8 MPa, preferably 0.2 MPa to 0.8 MPa, more preferably 0.25 MPa to 0.75 MPa, and even more preferably 0.30 MPa to 0.70 MPa. The treatment time is preferably 5 minutes or more, particularly 5 minutes or more or 60 minutes or less, and more preferably 10 minutes or more or 45 minutes or less.

[0129] Next, the pressure-sensitive adhesive sheet sandwiched between the first and second image display components is irradiated with active energy rays to cure the pressure-sensitive adhesive sheet, thereby producing the laminate. In the above, the second image display device component may be a component having an uneven portion, such as a bottomed hole, on the contact surface with the adhesive sheet, and the present invention allows the adhesive composition to flow sufficiently into the bottomed hole of the second image display device component.

[0130] 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 2 is 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.

[0131] A preferred example of the present laminate is a laminate for constituting an image display device, which comprises two image display device components laminated together via a post-curing adhesive sheet having a thickness of 0.8 to 1.5 mm and a creep strain of 10% or more after 180 seconds at 80°C after curing under predetermined curing conditions. The post-curing adhesive sheet is the sheet obtained after the present adhesive sheet has been photocured. In this case, at least one of the components of the image display device has irregularities, for example, a depth (mm) / base area (mm 2 ) is 1.0 × 10 -5 ~3.0×10 -1In 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.

[0132] <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.

[0133] <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]

[0134] The present invention will be further explained by the following examples, but the present invention should not be construed as being limited to the examples shown below.

[0135] First, the raw materials of the pressure-sensitive adhesive compositions prepared in the examples will be described in detail.

[0136] <(Meth)acrylic polymer (A)> (Meth)acrylic polymer (A-1): an acrylic graft copolymer (mass average molecular weight: 330,000, Tg -42°C) obtained by random copolymerization of 6 parts by mass of polymethyl methacrylate macromonomer (Tg 105°C) having a number average molecular weight of 2,800, 74 parts by mass of butyl acrylate (Tg -55°C), and 20 parts by mass of 2-hydroxyethyl acrylate (Tg -15°C). (Meth)acrylic polymer (A-2): an acrylic graft copolymer (mass average molecular weight: 160,000, Tg -36°C) obtained by random copolymerization of 15 parts by mass of polymethyl methacrylate macromonomer (Tg 105°C) having a number average molecular weight of 2800, 81 parts by mass of butyl acrylate (Tg -50°C), and 4 parts by mass of acrylic acid (Tg 106°C).

[0137] The glass transition temperatures of the copolymerized components in the (meth)acrylic polymer are literature values ​​of the glass transition temperatures obtained from homopolymers of the components. For the macromonomer, the literature values ​​of the glass transition temperatures obtained from homopolymers of the components that form the high molecular weight skeleton in the macromonomer are listed. The glass transition temperature of the acrylic copolymer is shown as a theoretical Tg calculated by Fox's formula from the glass transition temperatures and composition ratios of the above-mentioned copolymer components.

[0138] <Crosslinking agent (B)> Crosslinking agent (B-1): Tricyclodecane dimethanol dimethacrylate Crosslinking agent (B-2): Propoxylated pentaerythritol triacrylate

[0139] <Polymerization initiator (C)> Initiator (C-1): A mixture of 2,4,6-trimethylbenzophenone and 4-methylbenzophenone (IGM "Esacure TZT")

[0140] [Example 1] A pressure-sensitive adhesive composition was prepared by uniformly mixing 100 parts by mass of the (meth)acrylic polymer (A-1), 5 parts by mass of the crosslinking agent (B-1), and 1.5 parts by mass of the initiator (C-1). The pressure-sensitive adhesive composition was spread in a sheet shape to a thickness of 100 μm on a silicone release-treated release film (PET film manufactured by Mitsubishi Chemical Corporation) having a thickness of 100 μm.

[0141] Next, a 75 μm thick release film (PET film manufactured by Mitsubishi Chemical Corporation) treated with silicone release agent was laminated on top of the sheet-shaped adhesive composition to form a laminate, thereby obtaining an adhesive sheet 1 with release film consisting of release film / adhesive sheet 1 / release film. The adhesive sheet 1 was an active energy ray-curable adhesive sheet having active energy ray-curability, which means that it is cured by irradiation with active energy rays.

[0142] [Examples 2 to 5, Comparative Examples 1 and 2] Pressure-sensitive adhesive sheets 2 to 7 were produced in the same manner as in Example 1, except that the formulation was changed as shown in Table 1.

[0143] Comparative Example 3 The (meth)acrylic polymer (A), crosslinking agent (B), and initiator (C) were mixed uniformly according to the formulation shown in Table 2 to obtain a pressure-sensitive adhesive composition, which was then spread into a sheet on a 100 μm-thick release film (PET film manufactured by Mitsubishi Chemical Corporation) that had been treated with silicone release agent to give a thickness of 100 μm. Next, a 75 μm thick release film (PET film manufactured by Mitsubishi Chemical Corporation) treated with silicone release agent was laminated on top of the sheet-shaped adhesive composition to form a laminate, thereby obtaining an intermediate layer adhesive sheet α1 with release film consisting of release film / adhesive sheet α1 / release film (thickness: 100 μm). In addition, the same procedure was carried out as above to obtain a release film-attached adhesive sheet β1 (thickness: 25 μm) for the surface layer consisting of release film / adhesive sheet β1 / release film, and a release film-attached adhesive sheet β'1 (thickness: 25 μm) for the back layer consisting of release film / adhesive sheet β'1 / release film. The release films on both sides of the adhesive sheet α1 with release film were sequentially peeled and removed, and the release films of the surface adhesive sheet β1 with release film and the backing adhesive sheet β'1 with release film were sequentially peeled and removed, thereby sequentially bonding the surface adhesive sheet β1 and the backing adhesive sheet β'1 to the front and back surfaces of the adhesive sheet α1, thereby obtaining an adhesive sheet 8 with release film consisting of release film / adhesive sheet 8 / release film, with an adhesive sheet 8 having a thickness of 150 μm consisting of (β1) / (α1) / (β'1). The adhesive sheet 8 was an active energy ray-curable adhesive sheet having active energy ray-curability, which is cured by irradiation with active energy rays.

[0144] [Physical property measurement and evaluation] The following various measurements and evaluations were carried out on the pressure-sensitive adhesive sheets 1 to 8 produced in the above Examples and Comparative Examples. The evaluation results are summarized in Tables 1 and 2.

[0145] <Creep test> Using multiple adhesive sheets prepared in each of the examples and comparative examples, the release films were peeled off and the adhesive sheets were stacked to a thickness of approximately 0.9 mm, and then an adhesive sheet with a release film consisting of release film / adhesive sheet stacked to a thickness of approximately 0.9 mm / release film was prepared, and this was then punched out into circles with a diameter of 8 mm using a punching machine. Using a rheometer (TA Instruments "DHR-2"), the strain (%) was measured after applying a measuring jig: 8 mm diameter parallel plates, a temperature: 50°C, and a pressure: 1000 Pa for 1200 seconds.

[0146] <Creep test (after hardening)> The pressure-sensitive adhesive sheets with release film prepared in the examples and comparative examples were irradiated with a high-pressure mercury lamp at a cumulative light intensity of 4000 mJ / cm at 365 nm. 2 The adhesive sheet was irradiated with ultraviolet light through a release-treated polyethylene terephthalate film to cure the adhesive sheet. The cured adhesive sheets were laminated to a thickness of approximately 0.9 mm and punched out into a circle with a diameter of 8 mm. Using a rheometer (TA Instruments "DHR-2"), the strain (%) was measured after applying a measuring jig: 8 mm diameter parallel plates, a temperature: 80°C, and a pressure: 1000 Pa for 180 seconds.

[0147] <Gel fraction> Approximately 0.1 g of adhesive sheet pieces were taken from each of the adhesive sheets produced in the Examples and Comparative Examples. The collected adhesive sheet pieces were wrapped in a bag-shaped SUS mesh (#150) with a mass (X), and the bag was closed to prepare a sample, and the mass (Y) of the sample was measured. The sample was immersed in ethyl acetate and stored in a dark place at 23°C for 24 hours, and then the sample was removed and heated at 70°C for 4.5 hours to evaporate the ethyl acetate, and the mass (Z) of the dried sample was measured. The gel fraction was calculated from each measured mass using the following formula: Gel fraction (%) = [(ZX) / (YX)] × 100

[0148] The pressure-sensitive adhesive sheets with release film prepared in the examples and comparative examples were irradiated with a high-pressure mercury lamp at a cumulative light intensity of 4000 mJ / cm at 365 nm. 2 The adhesive sheet was irradiated with ultraviolet light through the release film to cure the adhesive sheet. The gel fraction of the cured pressure-sensitive adhesive sheet after curing with active energy rays was determined in the same manner as in the gel fraction evaluation procedure described above.

[0149] <Adhesive strength> 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 then peeled off to expose the adhesive surface, which was then rolled back and forth against a soda lime glass to roll-press the adhesive sheet, which was then cured at 60°C for 30 minutes to complete the finish application. The adhesive strength measurement sample was peeled off from glass at a peel angle of 180° and a peel rate of 60 mm / min in an environment of 23°C and 40% RH, and the peel strength (N / cm) was measured.

[0150] <Adhesive strength (after curing)> One of the release films was peeled off from the adhesive sheets with release films prepared 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 the 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 23°C, and then cured for 15 hours to obtain a sample for measuring adhesive strength. 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.

[0151] <Oil resistance> The pressure-sensitive adhesive sheets with release films prepared in the Examples and Comparative Examples were cut into 10 mm x 10 mm squares, and one of the release films was peeled off to expose the surface of the pressure-sensitive adhesive sheet, which was used as a sample for measuring the oil swelling ratio. The oil swelling ratio measurement sample was immersed in an artificial sebum liquid (oleic acid:squalene=1:1) for 4 days in an environment of 25° C. The area of ​​the oil swelling ratio measurement sample before immersion in the artificial sebum liquid was designated as So, and the area of ​​the oil swelling ratio measurement sample after immersion in the artificial sebum liquid was designated as St, and the oil swelling ratio was calculated by the following formula (i). Oil swelling rate (%) = [(St-So) / So] × 100 (i)

[0152] <Hot melt properties> A 20 μm-thick double-sided adhesive sheet was hand-rolled onto one side of a 50 μm-thick polyethylene terephthalate film (Mitsubishi Chemical Corporation's "S-100, 50 μm thick") 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 4 mm-diameter bottomed holes were punched in the four corners of the cut film, with the distance from the edge to the hole center being 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.

[0153] One release film was removed from each of the pressure-sensitive adhesive sheets with release films 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 sheets were 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 hot-melt properties.

[0154] The laminate was visually observed, and if a void of 1 mm or more in diameter was found inside one or more bottomed holes, it was rated as "x (poor)", and otherwise it was rated as "◯ (good)". When the voids were non-spherical, the diameter of the voids was determined as the longest diameter.

[0155] <Storability> One release film was peeled off from the adhesive sheets with release films prepared in the Examples and Comparative Examples, and the adhesive sheets were cut into 30 mm x 30 mm squares. A release film was placed on top of the cut sheet, and a marking line corresponding to the dimensions of the adhesive sheet (30 mm x 30 mm square) was made in the release film (half cut). In this state, the adhesive sheet was stored in an environment of 40°C for 200 hours. The maximum amount of adhesive protrusion from the marking line was measured on each side of the adhesive sheet, and the average value of the four sides was taken as the adhesive protrusion distance (mm). A glue protrusion distance of less than 0.3 mm was judged as "◯ (good)", and a glue protrusion distance of 0.3 mm or more was judged as "× (poor)".

[0156] <Durability> The adhesive surface of an 87 μm thick polarizing plate (70 mm × 150 mm) with an adhesive layer was roll-bonded to a 75 mm × 155 mm, 0.55 mm thick soda lime glass sheet to prepare a substrate for durability evaluation consisting of a polarizing plate with an adhesive layer / soda lime glass sheet.

[0157] One release film was peeled off from each of the pressure-sensitive adhesive sheets with release films 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). Next, the remaining release film was peeled off, and the exposed adhesive surface was placed opposite the polarizing plate surface of the durability evaluation substrate, and the sheets 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 durability evaluation.

[0158] 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.

[0159] The reliability evaluation samples after storage were visually inspected, and samples that showed no glue overflow at the edge or air bubbles within the surface were judged as "○ (good)", and samples that showed glue overflow at the edge and / or air bubbles within the surface were judged as "× (poor)".

[0160] [Table 1]

[0161] [Table 2]

[0162] The pressure-sensitive adhesive sheets of the examples had creep characteristics and oil swelling ratios within the specified ranges, and were excellent in hot-melt properties, oil resistance, storage stability and durability. The adhesive sheets of Examples 1 to 4 contained a crosslinking agent, and had creep strains of 80% or less after curing at 80°C for 180 seconds. Therefore, they had superior durability in high and low temperature environments compared to the adhesive sheet of Example 5, which did not contain a crosslinking agent. On the other hand, the pressure-sensitive adhesive sheet 6 of Comparative Example 1 had a high oil swelling coefficient and poor oil resistance.In addition, the creep strain after 1200 seconds at 50°C was large, and the storage stability was poor. The pressure-sensitive adhesive sheet 7 of Comparative Example 2 had a high oil-induced swelling coefficient and poor oil resistance. In addition, the creep strain after 1200 seconds at 50° C. was small, and the hot-melt properties were insufficient. The adhesive sheet 8 of Comparative Example 3 satisfied the creep strain amount after 1200 seconds at 50°C, but had a high oil expansion coefficient and poor oil resistance. From the above, it is clear that it is difficult to achieve oil resistance, fluidity, and hot melt properties at the same time.

Claims

1. A pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer (A) and a polymerization initiator (C), or a pressure-sensitive adhesive composition containing a (meth)acrylic polymer (A), a crosslinking agent (B) and a polymerization initiator (C), the (meth)acrylic polymer (A) contains, as monomer components, an alkyl(meth)acrylate having an alkyl group with 6 or less carbon atoms and a vinyl monomer having a polar group, and the content of the vinyl monomer having a polar group is 10 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the acrylic polymer (A); the crosslinking agent (B) contains a polyfunctional (meth)acrylate, and the content of the crosslinking agent (B) is 20 parts by mass or less relative to 100 parts by mass of the (meth)acrylic polymer (A); An active energy ray-curable adhesive sheet that satisfies the following requirements (1) and (2): (1) The thickness is 0.8 to 1.5 mm, and the distortion (creep strain) after applying a pressure of 1000 Pa at a temperature of 50° C. for 1200 seconds is 150% or more and 1500% or less. (2) When the initial area of ​​the pressure-sensitive adhesive sheet is So and the area of ​​the pressure-sensitive adhesive sheet after immersion in an artificial sebum liquid (a 1:1 mixture of squalene and oleic acid) at 25°C for 4 days is St, the oil swelling rate calculated by the following formula (i) is 30% or less. Oil swelling rate (%) = [(St - So) / So] × 100 (i)

2. The active energy ray-curable pressure-sensitive adhesive sheet according to claim 1 , wherein the (meth)acrylic polymer (A) is a block copolymer and / or a graft copolymer.

3. The active energy ray-curable adhesive sheet according to claim 2, wherein the (meth)acrylic polymer (A) is a copolymer containing a structural unit derived from a macromonomer, and the copolymerization ratio of the macromonomer is 3 to 10 parts by mass per 100 parts by mass of the polymer (A).

4. The active energy ray-curable adhesive sheet according to any one of claims 1 to 3, wherein the (meth)acrylic polymer (A) has a content of alkyl (meth)acrylate in which the alkyl group has 6 or less carbon atoms in the monomer components forming the acrylic polymer (A) of 40 mass% or more.

5. The active energy ray-curable adhesive sheet according to any one of claims 1 to 4, excluding those in which the adhesive layer contains an ultraviolet absorber and a photopolymerization initiator having a molar absorption coefficient of 10 or more at a wavelength of 405 nm.

6. The active energy ray-curable adhesive sheet according to claim 5, wherein the crosslinking agent (B) is a polyfunctional (meth)acrylate (b-1) having a cyclic structure.

7. The active energy ray-curable adhesive sheet according to claim 5 or 6, wherein the content of the polyfunctional (meth)acrylate (b-1) is 0.5 parts by mass or more and 20 parts by mass or less relative to 100 parts by mass of the (meth)acrylic polymer (A).

8. The active energy ray-curable adhesive sheet according to any one of claims 1 to 7, wherein the gel fraction is 0% or more and 20% or less.

9. Active energy rays with a wavelength of 365 nm are used with an integrated light intensity of 4000 mJ / cm ２ The active energy ray-curable adhesive sheet according to any one of claims 1 to 8, wherein when the sheet is cured by irradiation, the gel fraction increases compared to before curing, and the gel fraction becomes 10% or more and 80% or less.

10. Active energy rays with a wavelength of 365 nm are used with an integrated light intensity of 4000 mJ / cm ２ 10. The active energy ray-curable adhesive sheet according to any one of claims 1 to 9, wherein when irradiated and cured, the active energy ray-curable adhesive sheet has a thickness of 0.8 to 1.5 mm and exhibits a distortion (creep strain) of 5% or more and 80% or less after application of a pressure of 1000 Pa at a temperature of 80°C for 180 seconds.

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, comprising two image display device constituent members laminated together via an active energy ray-curable adhesive sheet having an oil swelling rate of 30% or less as determined by the following formula (i): the pressure-sensitive adhesive sheet comprises a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer (A) and a polymerization initiator (C), or a pressure-sensitive adhesive resin composition containing a (meth)acrylic polymer (A), a crosslinking agent (B), and a polymerization initiator (C), the (meth)acrylic polymer (A) contains, as monomer components, an alkyl(meth)acrylate having an alkyl group with 6 or less carbon atoms and a vinyl monomer having a polar group, and the content of the vinyl monomer having a polar group is 10 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the acrylic polymer (A); the crosslinking agent (B) contains a polyfunctional (meth)acrylate, and the content of the crosslinking agent (B) is 20 parts by mass or less relative to 100 parts by mass of the (meth)acrylic polymer (A); The laminate for constituting an image display device has a thickness of 0.8 to 1.5 mm, and exhibits a distortion (creep strain) of 150% or more and 1500% or less after application of a pressure of 1000 Pa at a temperature of 50° C. for 1200 seconds. Oil swelling rate (%) = [(St - So) / So] × 100 (i) In formula (i), So is the initial area of ​​the adhesive sheet, and St is the area after the adhesive sheet has been immersed in an artificial sebum liquid (a 1:1 mixture of squalene and oleic acid) at 25°C for 4 days.

14. A laminate for constituting an image display device, comprising two image display device constituent members laminated together via a cured adhesive sheet obtained by curing an active energy ray-curable adhesive sheet having an oil swelling rate of 30% or less as determined by the following formula (i): the pressure-sensitive adhesive sheet comprises a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer (A) and a polymerization initiator (C), or a pressure-sensitive adhesive resin composition containing a (meth)acrylic polymer (A), a crosslinking agent (B), and a polymerization initiator (C), the (meth)acrylic polymer (A) contains, as monomer components, an alkyl(meth)acrylate having an alkyl group with 6 or less carbon atoms and a vinyl monomer having a polar group, and the content of the vinyl monomer having a polar group is 10 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the acrylic polymer (A); the crosslinking agent (B) contains a polyfunctional (meth)acrylate, and the content of the crosslinking agent (B) is 20 parts by mass or less relative to 100 parts by mass of the (meth)acrylic polymer (A); The laminate for constituting an image display device has a thickness of 0.8 to 1.5 mm, and exhibits a distortion (creep distortion) of 5% or more and 220% or less after application of a pressure of 1000 Pa at a temperature of 80° C. for 180 seconds. Oil swelling rate (%) = [(St - So) / So] × 100 (i) In formula (i), So is the initial area of ​​the adhesive sheet, and St is the area after the adhesive sheet has been immersed in an artificial sebum liquid (a 1:1 mixture of squalene and oleic acid) at 25°C for 4 days.

15. 15. The laminate for constituting an image display device according to claim 13 or 14, excluding those in which the pressure-sensitive adhesive sheet contains an ultraviolet absorber and has a pressure-sensitive adhesive layer containing a photopolymerization initiator having a molar absorption coefficient of 10 or more at a wavelength of 405 nm.

16. The laminate for constituting an image display device according to any one of claims 13 to 15, wherein the pressure-sensitive adhesive sheet has a multi-layer structure of two or more layers.

17. 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 The laminate for constituting an image display device according to any one of claims 13 to 16, having bottomed holes of the formula:

18. The image display device constituent member according to any one of claims 13 to 17, wherein the image display device constituent member is a laminate comprising any one or a combination of two or more of the group consisting of a touch panel, an image display panel, a surface protection panel, a polarizing film, and a retardation film. The laminate for constituting an image display device according to any one of claims 13 to 17.

19. An image display device constructed using the laminate for constituting an image display device according to any one of claims 13 to 18.

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