Active energy ray curable adhesive sheet, adhesive sheet laminate with release film, laminate for image display device component, image display device, and method for manufacturing the laminate for image display device component.

Abstract

Proposed is a new actinic-ray-curable pressure-sensitive adhesive sheet which can have both excellent flowability and storage stability and which can exhibit such reliable freedom from bubble inclusion that the adhesive sheet does not come to include bubbles even when the adhesive sheet is laminated to an adherend and finally cured and the adherend thereafter changes dimensionally. The actinic-ray-curable pressure-sensitive adhesive sheet includes a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition including a (meth)acrylic polymer (A). The actinic-ray-curable pressure-sensitive adhesive sheet, in a given holding-power test (500 gf after 40°C, 10 minutes), has a position shift less than 2 mm. The actinic-ray-curable pressure-sensitive adhesive sheet of 0.8-1.5 mm in thickness, before final curing, has a creep strain of 40-1,500% after standing at 25°C for 3,600 seconds and, after final curing performed under given curing conditions, has a creep strain of 10% or greater after standing at 80°C for 180 seconds.

Description

[Technical Field]

[0001] The present invention relates to an active energy ray curable adhesive sheet having the property of curing by active energy rays, a laminate for an image display device using the same, an image display device, and a method for manufacturing the laminate for an image display device. [Background technology]

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

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

[0004] Furthermore, a method for filling the gaps between components of an image display device using an adhesive sheet is also known. For example, Patent Document 2 discloses a method for manufacturing a laminate for an image display device, which has a configuration in which image display device components are laminated on at least one side of a transparent double-sided adhesive sheet. This method involves bonding an adhesive sheet that has been primary crosslinked by ultraviolet light to the image display device components, and then irradiating the adhesive sheet with ultraviolet light through the image display device components to perform secondary curing.

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

[0006] (Patent Document 4) discloses a photocurable adhesive sheet used for bonding 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, which is characterized by having an adhesive layer (Y) having all of the following characteristics (1) to (3). (1) The gel fraction (referred to as "gel fraction X1 before light irradiation") 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 photocurability that cures by irradiation with light having a wavelength of 405 nm.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0008] In recent years, there has been a trend in image display devices such as mobile phones to have a design where almost the entire area of ​​the image display panel is used as the display, and consequently, cameras are increasingly being placed within the display area. There are two methods for placing a camera within the display: one is to make a hole in the image display panel itself and allow the camera lens to penetrate to just below the surface protective panel, and the other is to place the camera in the layer below the image display panel. In the latter method, since the camera needs to be placed through the image display panel, a functional layer such as a polarizing film or reflective film laminated on the surface of the image display panel is configured to have holes that match the position and size of the camera in order to ensure light transmission to the camera lens.

[0009] Furthermore, adhesive sheets used to bond together image display device components with such holes require properties (fluidity) that allow the adhesive to flow into the holes and fill every corner. On the other hand, while adhesive sheets require fluidity, this can lead to reduced storage stability. Therefore, there is a need to achieve a balance between these conflicting physical properties: fluidity and storage stability. Furthermore, stress tends to concentrate near holes in the components of an image display device as the dimensions of the component change. In particular, the adhesive filling the holes may peel off or foam, which may reduce light transmittance. Therefore, the adhesive sheet is required to have the property of not foaming even if the dimensions of the adherend change after it has been laminated and cured (foaming resistance reliability).

[0010] Furthermore, Patent Document 2 mentioned above uses an adhesive sheet that has been primary crosslinked by ultraviolet light, and it is assumed that storage stability is obtained because the adhesive sheet has been primary crosslinked. However, such an adhesive sheet is exposed to 1000 mJ / cm 2 Because the material is cross-linked by UV irradiation, its ability to conform to the inside of pores is still not satisfactory. Furthermore, Patent Document 3, mentioned above, uses an adhesive sheet containing an acrylic copolymer made of a graft copolymer with macromonomers as branch components, a crosslinking agent, and a photopolymerization initiator, to obtain an adhesive sheet without primary curing. However, such an adhesive sheet does not have sufficient fluidity.

[0011] Furthermore, in recent years, when image display device components equipped with holes for positioning cameras within the display are laminated via adhesive sheets, there is a demand to improve productivity by shortening the cycle time and lowering the hole-filling temperature. Therefore, the adhesive sheets in question require even greater fluidity than before. Thus, while there is a demand for adhesive sheets that excel in both fluidity (conformability) and storage stability, the fact that these are conflicting physical properties means that a satisfactory product has yet to be achieved.

[0012] The present invention aims to provide a novel active energy ray curable adhesive sheet, an adhesive sheet having the property of curing by active energy rays, a laminate for an image display device using the same, and a method for manufacturing the same, which can achieve both excellent fluidity and storage stability, and furthermore exhibit foam resistance reliability such as not foaming even if the adherend changes in size after being laminated and cured on the adherend. [Means for solving the problem]

[0013] The active energy ray curable adhesive sheet, adhesive sheet laminate with release film, laminate for image display device component, image display device, and method for manufacturing the laminate for image display device component proposed by the present invention have the following configuration in order to solve the above problems.

[0014] [1] A first aspect of the present invention is an active energy ray curable adhesive sheet comprising an adhesive layer formed from an adhesive composition containing a (meth)acrylic polymer (A), The aforementioned active energy ray-curable adhesive sheet exhibits a displacement of less than 2 mm in the following (1) retention strength test: When the thickness is 0.8 to 1.5 mm, the creep strain after 3600 seconds at 25°C before curing is between 40% and 1500%. This is an active energy ray curable adhesive sheet in which the creep strain after curing under the following curing conditions (2) at 80°C for 180 seconds is 10% or more. (1) Holding power test: An active energy ray curable adhesive sheet (25 mm wide x 100 mm long, in strip form) with polyethylene terephthalate film attached to one side is attached to a stainless steel plate (120 mm x 50 mm x 1.2 mm thick) using a hand roller to create a test specimen with an adhesive area of ​​25 mm x 20 mm. The test specimen is cured in a 40°C environment for 15 minutes, and then a 500 gf (4.9 N) weight is attached vertically to the other end of the adhesive sheet and left to stand. After 10 minutes, the length (mm) by which the adhesive sheet has shifted downward relative to the stainless steel plate is measured. (2) Curing conditions: 3000-4000 mJ / cm² under 365 nm ultraviolet light. 2 The process involves curing the substance by irradiating it with an accumulated amount of light within a certain range.

[0015] [2] A second aspect of the present invention is an active energy ray curable adhesive sheet, in the first aspect, wherein the adhesive composition further comprises a crosslinking agent (B) and an initiator (C). [3] A third aspect of the present invention is an active energy ray curable adhesive sheet in which the crosslinking agent (B) comprises a polyfunctional (meth)acrylate component (b-1) having two or more (meth)acryloyl groups. [4] A fourth aspect of the present invention is an active energy ray curable adhesive sheet in which, in the second or third aspect, the content of the crosslinking agent (B) in the adhesive composition is 0.2 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the (meth)acrylic polymer (A).

[0016] [5] A fifth aspect of the present invention is an active energy ray curable adhesive sheet having a multi-layer structure of two or more layers, according to any one of the first to fourth aspects. [6] A sixth aspect of the present invention is an active energy ray curable adhesive sheet in any one of the first to fifth aspects, wherein the (meth)acrylic polymer (A) is a block copolymer and / or a copolymer containing structural units derived from macromonomers as branch components. [7] A seventh aspect of the present invention is an active energy ray curable adhesive sheet in any one of the first to sixth aspects, wherein the (meth)acrylic polymer (A) is a copolymer containing structural units derived from macromonomers as branch components, and the copolymerization ratio of macromonomers is 1 to 10% by mass. [8] An eighth aspect of the present invention is the amount of 10 to 500 mJ / cm² in any one of the first to seventh aspects. 2 This is an active energy ray curable adhesive sheet, which is an adhesive sheet that has been partially cured by irradiation with active energy rays. [9] The ninth aspect of the present invention is an active energy ray curable adhesive sheet in any one of the first to eighth aspects, wherein the creep strain after 3600 seconds at 25°C before curing is 50% or more and 1500% or less when the thickness is 0.8 to 1.5 mm.

[0017]

[10] A tenth aspect of the present invention is an adhesive sheet laminate with a release film, comprising an active energy ray curable adhesive sheet according to any one of the first to ninth aspects and a release film laminated together.

[0018]

[11] An eleventh aspect of the present invention is an active energy ray curable adhesive sheet obtained by curing an active energy ray curable adhesive sheet according to any one of the first to ninth aspects.

[0019]

[12] A twelfth aspect of the present invention is a laminate for an image display device, comprising a configuration in which two image display device components are laminated with an adhesive sheet in between, The aforementioned adhesive sheet comprises an adhesive layer formed from an adhesive composition containing a (meth)acrylic polymer (A), and when the thickness is 0.8 to 1.5 mm, the creep strain after 3600 seconds at 25°C before curing is 40% or more and 1500% or less, and the creep strain after 180 seconds at 80°C after curing under the following curing conditions is 10% or more, and is an active energy ray curable adhesive sheet. At least one of the image display device components has a contact surface with the adhesive sheet, with a depth (mm) / bottom area (mm). 2 ) is 1.0 × 10 -5 ~3.0×10 -1 This is a laminate for an image display device, characterized by having a bottomed hole. Curing conditions: 365nm ultraviolet light at 3000-4000 mJ / cm² 2 The process involves curing the substance by irradiating it with an accumulated amount of light within a certain range.

[0020]

[13] A thirteenth aspect of the present invention is a laminate for an image display device, in the twelfth aspect, wherein the adhesive sheet has a thickness of 0.8 to 1.5 mm and the creep strain after 3600 seconds at 25°C before curing is 50% to 1500%.

[14] A fourteenth aspect of the present invention is, in the twelfth or thirteenth aspect, the adhesive sheet having a concentration of 10 to 500 mJ / cm². 2 This is a laminate for image display device components, which is an adhesive sheet that has been partially cured by irradiation with active energy rays.

[15] A fifteenth aspect of the present invention is a laminate for an image display device, in any one of the twelve to fourteen aspects, wherein the image display device component consists of one or more combinations of the group consisting of a touch panel, an image display panel, a surface protection panel, a polarizing film, and a phase difference film.

[0021]

[16] A sixteenth aspect of the present invention is an image display device configured using a laminate for image display device configuration according to any one of the twelve to fifteen aspects.

[0022]

[17] The 17th aspect of the present invention is a method for manufacturing a laminated body for an image display device configuration, comprising a configuration in which two image display device constituent members are laminated via an adhesive sheet after curing of an active energy ray-curable adhesive sheet according to any one of the 1st to 9th aspects, A bonded body is formed by bonding the adhesive sheet to one side of the first image display device constituent member, and the bonded surface of the second image display device constituent member having a bottomed hole on the bonded surface is faced to the adhesive sheet of the bonded body, and they are adhered and laminated under reduced pressure to form a laminated body, By subjecting the laminated body to a heat and pressure treatment to hot-melt the adhesive sheet, an adhesive composition is caused to flow into the bottomed hole of the second image display device constituent member, An active energy ray is irradiated to the adhesive sheet sandwiched between the first and second image display device constituent members to cure the adhesive sheet, which is a method for manufacturing a laminated body for an image display device configuration.

[0023]

[18] The 18th aspect of the present invention is, in the 17th aspect, the bottomed hole of the second image display device constituent member has a depth (mm) / bottom area (mm 2 ) of 1.0×10 -5 ~3.0×10 -1 which is a method for manufacturing a laminated body for an image display device configuration.

[19] The 19th aspect of the present invention is, in the 17th or 18th aspect, the cured adhesive sheet has a creep strain of 10% or more after 180 seconds at 80°C when the thickness is 0.8 to 1.5 mm, which is a method for manufacturing a laminated body for an image display device configuration.

[20] The 20th aspect of the present invention is, in any one of the 17th to 19th aspects, the heat and pressure treatment for the laminated body is performed at a temperature of 40°C or higher and 80°C or lower, and a pressure of 0.2 MPa or higher and 0.8 MPa or lower is applied to the laminated body, which is a method for manufacturing a laminated body for an image display device configuration.

Advantages of the Invention

[0024] The active energy ray-curable adhesive sheet proposed in this invention can be hot-melted by heating and pressurizing, exhibiting excellent fluidity. Therefore, the hot-melted adhesive composition can be allowed to flow into the pores of the adherend and fill every corner. Furthermore, by laminating the adhesive sheet between two adherends and curing it by irradiation with active energy rays, it is possible to join two adherends, particularly components of an image display device. Moreover, even if the dimensions of the adherends change, the adhesive filling the pores will not foam, exhibiting excellent foam resistance reliability. [Modes for carrying out the invention]

[0025] Next, the present invention will be described based on examples of embodiments. However, the present invention is not limited to the embodiments described below.

[0026] <This adhesive sheet> An example of an embodiment of the present invention (referred to as "the adhesive sheet") is an active energy ray curable adhesive sheet comprising an adhesive layer (referred to as "the adhesive layer") formed from an adhesive composition (referred to as "the adhesive composition") containing a (meth)acrylic polymer (A).

[0027] The aforementioned "active energy ray curable adhesive sheet" refers to an adhesive sheet that has the property of being curable by active energy rays, or in other words, an adhesive sheet that has active energy ray curability and retains the potential for curing by active energy rays. This adhesive sheet may be cured in a state where there is still room for further curing by active energy rays (also referred to as "partially cured"), or it may be uncured at all ("uncured") and capable of being cured by active energy rays. If the adhesive sheet is partially cured or uncured, after adhering it to the substrate, the adhesive sheet can be cured using active energy rays (also referred to as "final curing"), thereby increasing cohesive force and improving adhesion.

[0028] The adhesive layer constituting part or all of this adhesive sheet is preferably in an uncrosslinked state, i.e., a state with a gel fraction of 0%, before being cured by active energy rays, from the viewpoint of facilitating its flow into the bottomed pores on the adherend surface. On the other hand, from the viewpoint of obtaining excellent storage stability, it is preferable that the material be in a partially cross-linked, pre-cured state before full curing. From the viewpoint of balancing storage stability and fluidity, the gel fraction in the pre-cured state is preferably 50% or less, more preferably 40% or less, even more preferably 20% or less, and particularly preferably 10% or less. Among these, the most preferable is a pre-cured state in which almost no solvent-insoluble components are generated, i.e., the gel fraction is 5% or less, and especially 1% or less, because it can improve storage stability without impairing fluidity. The lower limit is 0% or more. When pre-curing this adhesive sheet, pre-curing may be done by heat or by active energy rays. From the viewpoint of easily controlling the gel fraction within a predetermined range, it is preferable that the adhesive sheet be pre-cured by irradiation with active energy rays. When this adhesive sheet is partially cured using activated energy rays, the energy charge is 10-500 mJ / cm². 2 Pre-curing is preferably achieved by irradiation with active energy rays. In such active energy ray irradiation, the preferred irradiation dose is, among others, 50 mJ / cm². 2 Above or above 450 mJ / cm 2 The following, and more preferably 100 mJ / cm² 2 Above or above, or 400 mJ / cm² 2 The following is particularly preferred: 150 mJ / cm 2 Above or above 350 mJ / cm² 2 More preferably, 200 mJ / cm 2 Above or above 300 mJ / cm² 2 The following applies: If the irradiation dose is within the above range, it tends to maintain fluidity while ensuring storage stability, which is preferable. Furthermore, when irradiating with active energy rays from both sides, the activated energy ray dose is the sum of the cumulative dose from one side and the cumulative dose from the other side.

[0029] This adhesive sheet may have a single-layer structure consisting of this adhesive layer, or it may have a multi-layer structure of two or more layers, each equipped with this adhesive layer. If the adhesive sheet has a multi-layer structure of two or more layers, it is preferable that at least the outermost layer, the innermost layer, or both of these layers are the adhesive layers. It is also possible that all layers are the adhesive layers.

[0030] The thickness of this adhesive sheet is preferably 10 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.

[0031] 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 accompanies the total thickness of the adhesive sheet to be 20-100%, and more preferably 30% or more or 95% or less, and more preferably 40% or more or 90% or less.

[0032] In the following holding strength test, it is preferable that the amount of displacement of this adhesive sheet is less than 2 mm. Holding power test: An active energy ray curable adhesive sheet (25 mm wide x 100 mm long, in strip form) with polyethylene terephthalate film attached to one side is attached to a stainless steel plate (120 mm x 50 mm x 1.2 mm thick) using a hand roller to create a test specimen with an adhesive area of ​​25 mm x 20 mm. The test specimen is cured in a 40°C environment for 15 minutes, then a 500 gf (4.9 N) weight is attached vertically to the other end of the adhesive sheet and left to stand. After 10 minutes, the length (mm) by which the adhesive sheet's attachment position relative to the stainless steel plate has shifted downwards is measured.

[0033] In this adhesive sheet, it is preferable if the amount of displacement in the above-mentioned holding power test is less than 2 mm, as this indicates excellent storage stability. From this viewpoint, it is even more preferable if the amount of displacement is 1.8 mm or less, and among those, 1.5 mm or less, and even more preferable if it is 1.0 mm or less. On the other hand, the lower limit of the displacement in the above holding force test is usually 0 mm and is not particularly limited. However, in order to facilitate the flow filling of the adhesive into uneven areas such as bottomed holes, the preferred lower limit of the displacement is 0.2 mm or more, more preferably 0.3 mm or more, even more preferably 0.4 mm or more, and particularly preferably 0.5 mm or more.

[0034] In this adhesive sheet, to adjust the amount of displacement in the above-mentioned retention force test to within the above-mentioned range, it is preferable to adjust the composition and molecular weight of the (meth)acrylic polymer (A), adjust the type and amount of the crosslinking agent (B) described later, or adjust the irradiation dose of the active energy rays. However, the method is not limited to this.

[0035] Preferably, when the thickness of this adhesive sheet is 0.8 to 1.5 mm, the creep strain after 3600 seconds at 25°C before curing is 40% or more and 1500% or less. In this adhesive sheet, it is preferable if the creep strain after 3600 seconds at 25°C is 40% or more, as this allows the adhesive to flow and fill into uneven areas such as bottomed holes upon heating. From this viewpoint, it is more preferable that the creep strain is 50% or more, even more preferable that it is 53% or more, and among those, 55% or more, and even more preferable that it is 60% or more. On the other hand, if the creep strain after 3600 seconds at 25°C is 1500% or less, it is preferable from the standpoint of excellent dimensional stability of the adhesive sheet. From this viewpoint, it is even more preferable that the creep strain is 1400% or less, and more preferably 1300% or less, particularly 1200% or less, even more preferably 800% or less, and especially 600% or less. In this adhesive sheet, to adjust the creep strain before curing to the above range, it is preferable to adjust the composition and molecular weight of the (meth)acrylic polymer (A), or to adjust the type and amount of the crosslinking agent (B) described later. Alternatively, the adhesive sheet may be pre-cured to adjust the creep strain. However, this method is not limited to this.

[0036] Preferably, when the thickness of this adhesive sheet is 0.8 to 1.5 mm, the creep strain after curing at 80°C for 180 seconds under the following curing conditions is 10% or more. Curing conditions: 365nm ultraviolet light at 3000-4000 mJ / cm² 2 The process involves curing the substance by irradiating it with an accumulated amount of light within a certain range. Furthermore, when ultraviolet light is irradiated from both sides, the accumulated light quantity is the sum of the accumulated light quantity from one side and the accumulated light quantity from the other side.

[0037] In this adhesive sheet, it is preferable that the creep strain after curing at 80°C for 180 seconds is 10% or more, as this prevents foaming and peeling at the interface with the adherend and allows it to follow the thermal dimensional changes of the adherend. From this viewpoint, it is even more preferable that the creep strain is 12% or more, and among those, 13% or more, and even more preferable that it is 15% or more. On the other hand, the upper limit of creep strain after 180 seconds at 80°C is not particularly limited. However, the upper limit is approximately 1000%, and the preferred upper limit of said creep strain is 500% or less, more preferably 300% or less, and particularly preferably 100% or less. If the creep strain is too high, the adhesive sheet may protrude from the end face of the bonded member in a high-temperature environment, causing the end face to become sticky, or the bonded member may shift position. In this adhesive sheet, to adjust the post-curing creep strain to the above range, it is preferable to adjust the composition and molecular weight of the (meth)acrylic polymer (A), adjust the type and amount of the crosslinking agent (B) described later, or adjust the irradiation dose of active energy rays during curing. However, the method is not limited to this.

[0038] As described above, the creep strain in this adhesive sheet is the value obtained when the thickness is 0.8 to 1.5 mm. 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. For this reason, it is necessary to adjust the adhesive sheet to a certain thickness range before measurement. By pre-adjusting the thickness of this adhesive sheet within the above range and then measuring the creep strain, the creep strain of this adhesive sheet can be accurately determined without being affected by the measurement jig.

[0039] Furthermore, the phrase "when the thickness is set to 0.8 to 1.5 mm" means that if the thickness of the adhesive sheet used as the measurement sample is less than this range, the thickness of the measurement sample should be adjusted to this range by stacking several sheets or similar means, and then the measurement should be taken. The same applies when the thickness of the measurement sample is specified in other tests.

[0040] It is preferable that this adhesive sheet has a gel fraction of 50% or more after curing under the following curing conditions. Curing conditions: 365nm ultraviolet light at 3000-4000 mJ / cm² 2 The process involves curing the substance by irradiating it with an accumulated amount of light within a certain range.

[0041] In this adhesive sheet, it is preferable that the gel fraction after curing is 50% or more, as this prevents foaming and peeling at the interface with the adherend, resulting in a highly reliable adhesive sheet. From this viewpoint, it is even more preferable that the gel fraction is 55% or more, and among those, 60% or more, and even more preferable that it is 65% or more. On the other hand, the upper limit of the gel fraction after curing is not particularly limited and is usually 100%, but from the viewpoint of following thermal dimensional changes, it is preferably 98% or less, more preferably 96% or less, even more preferably 93% or less, and particularly preferably 90% or less. In this adhesive sheet, to adjust the gel fraction after curing to the above range, it is preferable to adjust the composition and molecular weight of the main component, the (meth)acrylic polymer (A), or to adjust the type and amount of the crosslinking agent (B) described later, or to adjust the amount of active energy radiation irradiated during curing. However, the method is not limited to this.

[0042] <This adhesive composition> This adhesive composition comprises a (meth)acrylic polymer (A), and optionally a crosslinking agent (B) and an initiator (C), and optionally other components.

[0043] <(meth)acrylic polymer (A)> In this adhesive composition, the (meth)acrylic polymer (A) is preferably the main component. That is, it is preferably the component with the highest mass percentage among the components constituting this adhesive composition. In this case, the mass percentage of the (meth)acrylic polymer (A) among the components constituting this adhesive composition may be 50% by mass or more, of which 70% by mass or more, of which 80% by mass or more, or of which 90% by mass or more. The (meth)acrylic polymer (A) may also include two or more copolymers with different polymerization components.

[0044] The (meth)acrylic polymer (A) is preferably one that contains 50% by mass or more of a monomer component represented by the following formula 1 (wherein R1 represents a hydrogen atom or a methyl group, and R2 represents a linear or branched alkyl group having 4 to 18 carbon atoms) as a polymerization component.

[0045] In particular, the (meth)acrylic polymer (A) is more preferably one that contains 55% by mass or more of the monomer component as a polymerization component, and among these, one that contains 60% by mass or more is especially preferred.

[0046] In this invention, "(meth)acrylic" encompasses acrylic and methacrylic, "(meth)acryloyl" encompasses acryloyl and methacryloyl, and "(meth)acrylate" encompasses acrylate and methacrylate. "(co)polymer" encompasses polymers and copolymers.

[0047] [ka]

[0048] Examples of monomers represented by formula 1 include n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, and isononyl (meth)acrylate. Examples include 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, dicyclopentenyl (meth)acrylate, etc. These may be used individually or in combination of two or more. These can be used individually or in combination of two or more. Among the above, it is particularly preferable to include one or more alkyl(meth)acrylates having 4 to 18, preferably 4 to 15, alkyl groups such as n-butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, n-octyl(meth)acrylate, isooctyl(meth)acrylate, and lauryl(meth)acrylate.

[0049] The (meth)acrylic polymer (A) is preferably a copolymer having "other copolymerizable monomers" other than the monomer component as copolymer components.

[0050] The aforementioned "other copolymerizable monomers" are preferably present in the (meth)acrylic polymer (A) in an amount of 1 to 50% by mass, more preferably in an amount of 2% or more by mass or 40% or less by mass, more preferably in an amount of 3% or more by mass or 35% or less by mass, and even more preferably in an amount of 5% or more by mass or 30% or less by mass. The lower and upper limits of the content can be combined arbitrarily.

[0051] 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"), and (e) amide group-containing monomers (hereinafter also referred to as "copolymerizable monomer a5"). Examples include (f) vinyl monomers (hereinafter also referred to as "copolymerizable monomer a6"), (g) (meth)acrylate monomers with 1 to 3 carbon atoms in the alkyl group (hereinafter also referred to as "copolymerizable monomer a7"), (h) macromonomers (hereinafter also referred to as "copolymerizable monomer a8"), (i) aromatic monomers (hereinafter also referred to as "copolymerizable monomer a9"), and (j) other functional group-containing monomers (hereinafter also referred to as "copolymerizable monomer a10"). These can be used individually or in combination of two or more.

[0052] Examples of 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 individually or in combination of two or more.

[0053] Examples of copolymerizable monomer a2 include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. These may be used individually or in combination of two or more.

[0054] Examples of 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 such as N,N-dimethylaminoethyl(meth)acrylate and N,N-dimethylaminopropyl(meth)acrylate. These may be used individually or in combination of two or more.

[0055] Examples of copolymerizable monomer a4 include glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate glycidyl ether. These may be used individually or in combination of two or more.

[0056] Examples of 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 individually or in combination of two or more.

[0057] Examples of copolymerizable monomer a6 include compounds having a vinyl group in the molecule. Examples of such compounds include alkyl (meth)acrylates having 1 to 12 carbon atoms in the alkyl group, functional monomers having functional groups such as a hydroxyl group, an amide group, and an alkoxyalkyl group in the molecule, polyalkylene glycol di(meth)acrylates, vinyl ester monomers such as vinyl acetate, N-vinyl-2-pyrrolidone, vinyl propionate, and vinyl laurate, and aromatic vinyl monomers such as styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene, and other substituted styrenes. These may be used individually or in combination of two or more.

[0058] Examples of copolymerizable monomer a7 include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, etc. These may be used individually or in combination of two or more.

[0059] The macromonomer, as the copolymerizable monomer a8, is a high-molecular-weight monomer having terminal functional groups and a high-molecular-weight backbone component. The number-average molecular weight of the macromonomer is preferably 1000 or more, more preferably 1500 or more, and even more preferably 2000 or more. The upper limit of the number-average molecular weight is usually 10000. Furthermore, specific examples of copolymerizable monomer a8 include, for example, polymethyl methacrylate macromonomers.

[0060] By using copolymerizable monomer a8, a graft copolymer can be obtained in which structural units derived from macromonomers are introduced as branch components of the graft copolymer, and a (meth)acrylic polymer (A) can be obtained consisting of such a graft copolymer. Therefore, the properties of the graft copolymer can be altered by selecting copolymerizable monomer a8 and other monomers, as well as by changing their blending ratios. In particular, in the present invention, the copolymerization ratio of macromonomers in the (meth)acrylic polymer (A) is preferably 10% by mass or less in terms of imparting fluidity during hot melting, more preferably 2% by mass or more or 9% by mass or less, particularly preferably 3% by mass or more or 8% by mass or less, and especially preferably 4% by mass or more or 7% by mass or less.

[0061] The skeletal component of the macromonomer is preferably composed of a (meth)acrylic acid ester polymer or a vinyl polymer. Examples include linear or branched alkyl (meth)acrylates with 4 to 18 carbon atoms in the alkyl group, alicyclic alkyl (meth)acrylates, copolymerizable monomer a1, copolymerizable monomer a2, copolymerizable monomer a7, etc., which can be used individually or in combination of two or more.

[0062] Examples of copolymerizable monomer a9 include benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and nonylphenol EO-modified (meth)acrylate. These may be used individually or in combination of two or more.

[0063] Examples of copolymerizable monomer a10 include (meth)acrylic-modified silicones, fluorine-containing monomers such as 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)acrylate, and 1H,1H,2H,2H-tridecafluoro-n-octyl (meth)acrylate. These may be used individually or in combination of two or more.

[0064] The (meth)acrylic polymer (A) is preferably free from or substantially free from the "copolymerizable monomer a1" from the viewpoint of preventing metal corrosion and resistance to humid heat whitening. Furthermore, "not containing or substantially not containing copolymerizable monomer a1" means not only that it is completely absent, but also that copolymerizable monomer a1 may be present in the (meth)acrylic acid ester (co)polymer at a concentration of less than 0.5% by mass, preferably less than 0.1% by mass.

[0065] The (meth)acrylic polymer (A) is preferably composed of a hydroxyl group-containing monomer and / or a nitrogen atom-containing monomer, from the viewpoint of imparting adhesive strength and cohesive force to the adhesive. Therefore, the (meth)acrylic polymer (A) is particularly preferably composed of the "copolymerizable monomer a2" and a nitrogen atom-containing monomer, especially "copolymerizable monomer a5," as copolymer components.

[0066] The (meth)acrylic polymer (A) is preferably a block copolymer and / or a graft copolymer, and more preferably a graft copolymer, from the viewpoint of imparting hot-melt properties to the adhesive. Here, a block copolymer refers to a block copolymer having multiple polymer chains containing repeating units derived from (meth)acrylic acid esters, in which multiple polymer chains with different chemical structures are linked linearly. Here, it is preferable that the graft copolymer contains repeating units derived from (meth)acrylic acid ester as the trunk component and repeating units derived from macromonomers as the branch components of the graft copolymer.

[0067] In the present invention, the glass transition temperature of the (meth)acrylic polymer (A) is preferably -70°C to 0°C, and more preferably -65°C or higher or -5°C or lower, and more preferably -60°C or higher or -10°C or lower, and even more preferably -55°C or higher or -20°C or lower.

[0068] In this context, the glass transition temperature of the copolymer component refers to the value calculated using Fox's formula, based on the glass transition temperatures and composition ratios of the polymers obtained from the homopolymers of each copolymer component.

[0069] Fox's formula is a calculation that can be obtained using the following formula, and the values ​​listed in the Polymer Handbook [Polymer Handbook, J. Brandrup, Interscience, 1989] can be used to determine the value. 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 the monomer i homopolymer.]

[0070] When obtaining the above (meth)acrylic polymer (A), it is preferable that the glass transition temperature of at least one repeating unit derived from the (meth)acrylic acid ester in the acrylic polymer (A) is -70°C to 0°C. Examples of (meth)acrylic acid esters that constitute such repeating units include, but are not limited to, (meth)acrylic acid esters with alkyl groups having 4 to 20 carbon atoms, such as n-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, n-octyl acrylate, n-nonyl acrylate, n-decyl acrylate, 2-ethylhexyl methacrylate, 2-methylhexyl acrylate, isooctyl acrylate, isononyl acrylate, isodecyl acrylate, isodecyl methacrylate, isostearyl acrylate, isostearyl (meth)acrylate, branched stearyl acrylate, and branched stearyl (meth)acrylate.

[0071] Furthermore, it is preferable that the glass transition temperature of at least one repeating unit derived from (meth)acrylic acid ester in the acrylic polymer (A) is between 0°C and 120°C. Specifically, since this affects the hot melt temperature of the adhesive sheet, it is preferable that this glass transition temperature (Tg) is between 20°C and 120°C, more preferably between 30°C and 120°C, and even more preferably between 40°C or higher or 110°C or lower, and among those, between 50°C or higher or 100°C or lower. If repeating units with such a glass transition temperature (Tg) are available, excellent processability and storage stability can be maintained by adjusting the molecular weight, and the material can be adjusted to hot-melt at around 40°C to 80°C.

[0072] Examples of (meth)acrylic acid esters that constitute such repeating units include methyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n-butyl methcrete, t-butyl acrylate, isobutyl acrylate, isobutyl methacrylate, isobornyl acrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 1,4-cyclohexanedimethanol monoacrylate, tetrahydrofurfuryl methacrylate, benzyl acrylate, benzyl methacrylate, phenoxyethyl acrylate, phenoxyethyl methacrylate, and the like.

[0073] In the present invention, by using a block copolymer or a graft copolymer as the (meth)acrylic polymer (A), an adhesive sheet with excellent shape stability and hot-melt properties can be obtained. Block copolymers and graft copolymers can be produced by known methods. In particular, graft copolymers can be produced by using macromonomers as copolymer components, as described above.

[0074] When the (meth)acrylic polymer (A) is a copolymer containing structural units derived from macromonomers as branch components as described above, it is preferable that, from the viewpoint of imparting hot-melt properties, the (meth)acrylic polymer contains macromonomer-derived structural units in a proportion of 1% or more, 10% or less by mass, and more preferably 2% or more by mass, or 9% or less by mass. If the proportion of such macromonomer-derived structural units is 10% by mass or less, it is preferable in terms of imparting fluidity during hot melting. Furthermore, it is preferable that the amount of structural units derived from such macromonomers be 2% by mass or more, as this suppresses excessive flow during storage and hot melting. From this viewpoint, it is even more preferable that the amount of structural units derived from macromonomers be 3% by mass or more, and particularly preferable that it be 4% by mass or more. On the other hand, it is even more preferable that it be 9% by mass or less, particularly preferable that it be 8% by mass or less, and even more preferable that it be 7% by mass or less.

[0075] The glass transition temperature of the structural unit derived from the macromonomer is preferably 20°C to 150°C, more preferably 40°C to 130°C, and more preferably 60°C to 120°C.

[0076] The mass-average molecular weight of the acrylic polymer (A) is preferably 100,000 or more, more preferably 150,000 or more, and more preferably 200,000 or more, from the viewpoint of obtaining excellent durability. On the other hand, from the viewpoint of good coating suitability and conformability to uneven surfaces, it is preferably 1,000,000 or less, more preferably 900,000 or less, and more preferably 800,000 or less,

[0077] <Crosslinking agent (B)> The crosslinking agent (B) is not merely a diluent, but a compound or composition that undergoes polymerization or crosslinking reactions through radical reactions induced by active energy rays, thereby bonding with (meth)acrylic polymers or forming physical crosslinks. The inclusion of a crosslinking agent (B) in this adhesive composition can impart durability after curing. However, if the acrylic polymer (A) undergoes a hydrogen abstraction reaction through the action of an initiator (C) or the like, as described later, and can form a sufficient crosslinked structure within and / or between the copolymers, then the inclusion of a crosslinking agent (B) is not necessarily required.

[0078] From the viewpoint of ensuring that the adhesive sheet hardens when irradiated with active energy rays, the crosslinking agent (B) preferably contains a polyfunctional (meth)acrylate (b-1) having two or more (meth)acryloyl groups.

[0079] By including a polyfunctional (meth)acrylate (b-1) having two or more (meth)acryloyl groups as the crosslinking agent (B), the adhesive composition becomes more readily able to form a crosslinked structure, thereby promoting the crosslinking reaction of the (meth)acrylic polymer (A) and accelerating the curing of the adhesive composition. Furthermore, if necessary, in addition to the polyfunctional (meth)acrylate (b-1), a monofunctional (meth)acrylate (b-2) having one (meth)acryloyl group may be included to improve the ability to follow thermal dimensional changes of the adherend. In addition, by including a monofunctional (meth)acrylate (b-2) having one (meth)acryloyl group, the molecular weight between crosslinking points of the cured product can be increased, which increases the degree of freedom of movement of the molecular chains. As a result, when adherends are laminated via this adhesive sheet, even when the adherends undergo dimensional deformation due to repeated heating and cooling, the adhesive sheet made of this adhesive composition can deform in accordance with the deformation.

[0080] The crosslinking agent (B) content in this adhesive composition is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, per 100 parts by mass of (meth)acrylic polymer (A). The upper limit is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and more preferably 20 parts by mass or less.

[0081] Furthermore, the content of the polyfunctional (meth)acrylate (b-1) is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and particularly preferably 1.5 parts by mass or more, per 100 parts by mass of (meth)acrylic polymer (A), from the viewpoint of forming a cross-linked structure and imparting cohesive force after curing. The upper limit is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and particularly preferably 6 parts by mass or less.

[0082] Furthermore, when a monofunctional (meth)acrylate (b-2) is included, its content is preferably 2 parts by mass or more, more preferably 4 parts by mass or more, and particularly preferably 6 parts by mass or more, per 100 parts by mass of (meth)acrylic polymer (A), from the viewpoint of adjusting the crosslinking density and imparting appropriate flexibility to the cured product. The upper limit is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and particularly preferably 15 parts by mass or less.

[0083] The polyfunctional (meth)acrylate (b-1) is preferably a component whose glass transition temperature when formed as a homopolymer is higher than 0°C, more preferably 5°C or higher, and more preferably 10°C or higher. The upper limit is preferably 250°C or lower, more preferably 150°C or lower, and even more preferably 100°C or lower, from the viewpoint of obtaining flexibility. The "glass transition temperature when used as a homopolymer" mentioned above refers to the glass transition temperature of a homopolymer prepared by polymerizing only the polyfunctional (meth)acrylate (b-1). On the other hand, the monofunctional (meth)acrylate (b-2) is preferably a component whose glass transition temperature when it is a homopolymer is 0°C or lower, and more preferably -10°C or lower, and even more preferably -20°C or lower. The lower limit is usually -80°C.

[0084] Examples of polyfunctional (meth)acrylates (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 dimethacrylate, tricyclodecane dimethanol di(meth)acrylate, bisphenol A polyethoxy di(meth)acrylate, bisphenol A polypropoxy di(meth)acrylate, bisphenol F polyethoxy di(meth)acrylate, ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane trioxyethyl (meth)acrylate, ε-caprolactone modified tris( 2-Hydroxyethyl) isocyanurate tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propoxylated pentaerythritol tri(meth)acrylate, ethoxylated pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, polyethylene glycol di (meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, tris(acryloxyethyl) isocyanurate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol penta(meth)acrylate, neopentyl glycol di(meth)acrylate, neopentyl hydroxybivalate Examples include UV-curable polyfunctional (meth)acrylic monomers such as di(meth)acrylate of ε-caprolactone adducts of glycoglycol, trimethylolpropane tri(meth)acrylate, trimethylolpropane polyethoxytri(meth)acrylate, and ditrimethylolpropanetetra(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 individually or in combination of two or more.

[0085] Examples of monofunctional (meth)acrylates (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, dodecyl Isostearyl(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 Relate, norbornyl (meth)acrylate, adamantyl (meth)acrylate, tricyclodecane dimethanol acrylate, ethoxylated-o-phenylphenol acrylate, 2-hydroxy-o-phenylphenolpropyl acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, phenoxyethylene glycol (meth)acrylate, phenoxydiethylene glycol Recall (meth)acrylate, phenoxy polyethylene glycol (meth)acrylate, 2-hydroxy-o-phenylphenol propyl acrylate, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl tetrahydrophthalic acid, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 2-(meth)acryloyloxypropyl phthalic acid, 2-(meth)acryloyloxypropyl hydrophthalic acid, 2-(meth)acryloyloxypropyl hexahydrophthalic acid, 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, tricyclodecanedimethanol 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 individually or in combination of two or more.

[0086] <Initiator (C)> The initiator (C) can be any compound that generates radicals when exposed to active energy rays. Furthermore, if the acrylic polymer (A) has a structure that can be excited by irradiation with active energy rays, such as a benzophenone structure, and in that excited state can abstract hydrogen radicals from the system, or if an electron beam is used as the active energy ray, it is not necessarily required to include an initiator (C).

[0087] Initiators (C) are broadly classified into two types based on their radical generation mechanism: cleavage-type photoinitiators, which can generate radicals by cleaving and decomposing the single bonds of the initiator itself, and hydrogen abstraction-type photoinitiators, which form an excited complex with a hydrogen donor in the system and can transfer hydrogen from the hydrogen donor.

[0088] The initiator (C) may be either a cleavage-type photoinitiator or a hydrogen abstraction-type photoinitiator, and may be used individually or in combination with other initiators. Furthermore, one or more of each may be used in combination. In the present invention, hydrogen abstraction initiators are preferred because they can efficiently crosslink between molecules or within molecules. On the other hand, cleavage-type photoinitiators are preferable because, after light irradiation, they decompose into reaction products, thereby reducing the risk of discoloration caused by initiator residue after the photoreaction. In particular, cleavage-type photoinitiators that have absorption in the visible light range are preferable because they can be photocured with high efficiency, and after the photoreaction, they lose their absorption in the visible light range and become discolored.

[0089] Examples of cleavage-type photoinitiators include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexylphenyl 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-methylpropionyl)benzyl}phenyl]-2-methyl-propan-1-one, oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone), methyl phenylglyoxylate, and 2-benzyl-2-dimethylamino-1-(4 Examples include 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 their derivatives.

[0090] Examples of hydrogen abstraction type photoinitiators include benzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 4-(meth)acryloyloxybenzophenone, 2-methyl benzoylbenzoate, methyl benzoyl formate, 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 their derivatives.

[0091] The content of the initiator (C) is not particularly limited. As a guideline, it is preferable to include 0.1 to 10 parts by mass, more preferably 0.5 parts by mass or 5 parts by mass, and more preferably 1 part by mass or 3 parts by mass, per 100 parts by mass of (meth)acrylic polymer (A). The lower and upper limits of the initiator content can be combined arbitrarily.

[0092] <Other ingredients> Other components included in this adhesive composition may, as needed, include various additives such as tackifying resins, antioxidants, light stabilizers, metal deactivators, anti-aging agents, hygroscopic agents, polymerization inhibitors, ultraviolet absorbers, rust inhibitors, inorganic particles, and silane coupling agents. Furthermore, reaction catalysts such as tertiary amine compounds, quaternary ammonium compounds, and tin laurate compounds may be appropriately included as needed.

[0093] (Rust inhibitor) From the viewpoint of preventing corrosion of optical components, this adhesive composition may contain a rust inhibitor. Preferred rust inhibitors include triazoles and benzotriazoles. These may be used individually or in combination of two or more. The content of the rust inhibitor is preferably 0.01 to 5 parts by mass per 100 parts by mass of (meth)acrylic polymer (A), and more preferably 0.1 parts by mass or more, or 3 parts by mass or less. The lower and upper limits of the rust inhibitor content can be arbitrarily combined.

[0094] (Silane coupling agent) Silane coupling agents are organosilicon compounds containing one or more reactive functional groups and one or more alkoxy groups bonded to silicon atoms in their structure. Examples of the reactive functional groups include epoxy groups, (meth)acryloyl groups, mercapto groups, hydroxyl groups, carboxyl groups, amino groups, amide groups, and isocyanate groups. Among these, epoxy groups and mercapto groups are preferred in terms of the balance of durability.

[0095] The alkoxy group bonded to the silicon atom is preferably a carbon-1 to carbon-8 alkoxy group from the viewpoint of durability and storage stability, and is particularly preferably a methoxy group or an ethoxy group. The silane coupling agent may also have organic substituents other than the reactive functional group and the alkoxy group bonded to the silicon atom, such as alkyl groups and phenyl groups.

[0096] Examples of the silane coupling agent include monomer-type epoxy group-containing silane coupling agents such as silane compounds like 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, or the silane compound undergoes hydrolysis and condensation polymerization, or the silane compound is coupled with methyltriethoxysilane, ethyltriethoxysilane, etc. Oligomeric epoxy group-containing silane coupling agents which are silane compounds obtained by the co-condensation of alkyl group-containing silane compounds such as methyltrimethoxysilane and ethyltrimethoxysilane; monomeric mercapto group-containing silane coupling agents which are silane compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, γ-mercaptopropyldimethoxymethylsilane, and 3-mercaptopropylmethyldimethoxysilane; or in which a part of the silane compound undergoes hydrolysis and condensation polymerization, or the silane compound and methyl Oligomeric mercapto group-containing silane coupling agents, which are silane compounds formed by the co-condensation of alkyl group-containing silane compounds such as triethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane; (meth)acryloyl group-containing silane compounds such as 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-acryloxypropyltrimethoxysilane. Silane coupling agents containing amino groups such as N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, and N-phenyl-3-aminopropyltrimethoxysilane; silane coupling agents containing isocyanate groups such as 3-isocyanatetopropyltriethoxysilane;Examples include vinyl group-containing silane coupling agents such as vinyltrimethoxysilane and vinyltriethoxysilane. These can be used individually or in combination of two or more types.

[0097] Among these, epoxy group-containing silane coupling agents and mercapto group-containing silane coupling agents are preferred due to their superior durability, and epoxy group-containing silane coupling agents are preferred in particular.

[0098] The content of the silane coupling agent is preferably 0.005 to 10 parts by mass, particularly preferably 0.01 parts by mass or 5 parts by mass or less, and even more preferably 0.05 parts by mass or 1 part by mass or less, per 100 parts by mass of (meth)acrylic polymer (A). By using a predetermined amount of silane coupling agent, when this adhesive sheet is laminated onto an object having uneven surfaces, it can adhere firmly to and follow the uneven surfaces even when the object undergoes dimensional deformation due to repeated heating and cooling. The lower and upper limits of the silane coupling agent content can be arbitrarily combined.

[0099] (Block copolymer or graft copolymer) This adhesive composition may include block copolymers and / or graft copolymers as polymers other than the (meth)acrylic polymer (A) to impart hot-melt properties to the adhesive sheet. These copolymers preferably have at least one rubbery segment and at least one glassy segment.

[0100] Here, a block copolymer refers to a block copolymer having multiple polymer chains containing repeating units derived from a certain monomer, in which multiple polymer chains with different chemical structures are linked together linearly. Furthermore, a graft copolymer is a copolymer that contains repeating units derived from monomers as its trunk component, and repeating units derived from monomers different from the trunk component as its branch component.

[0101] The rubbery segment is the portion that exhibits a glass transition temperature (Tg) below room temperature, and the Tg of the rubbery segment is preferably less than 0°C, more preferably less than -10°C, and even more preferably less than -20°C. Examples of monomers constituting the rubbery segment include conjugated dienes and hydrogenated derivatives of conjugated dienes. Here, the conjugated diene preferably contains 4 to 15 carbon atoms. Examples of conjugated dienes include butadiene, isoprene, ethyl butadiene, phenyl butadiene, piperylene, pentadiene, hexadiene, ethylhexadiene, and dimethyl butadiene. 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 copolymer, and combinations thereof.

[0102] The glassy segment is the portion that exhibits a Tg above room temperature. 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 constituting the glassy segment include, but are not limited to, monovinyl aromatic monomers. Examples of monovinyl aromatic monomers include styrene, vinylpyridine, vinyltoluene, α-methylstyrene, methylstyrene, dimethylstyrene, ethylstyrene, diethylstyrene, t-butylstyrene, di-n-butylstyrene, isopropylstyrene, other alkylated styrenes, styrene analogs, and styrene analogs.

[0103] The content of block copolymers and / or graft copolymers other than (meth)acrylic polymer (A) is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and more preferably 5 parts by mass or more, per 100 parts by mass of (meth)acrylic polymer (A). The upper limit is preferably 100 parts by mass or less, more preferably 95 parts by mass or less, and more preferably 90 parts by mass or less.

[0104] (Plasticizer) This adhesive composition may contain a plasticizer to impart hot-melt properties to the adhesive sheet.

[0105] Examples of plasticizers are not limited to those listed above. For example, they could be selected from the group consisting of polyisobutylene, polyisoprene, polybutadiene, amorphous polyolefins and their copolymers, silicones, polyacrylates, oligomeric polyurethanes, ethylene propylene copolymers, or any combination or mixture thereof. Among these, polyisobutylene is preferred as the plasticizer. Examples of polyisobutylene plasticizers that can be used in this specification include those commercially available from BASF under the trade name OPPANOL, particularly those selected from the OPPANOLB series.

[0106] From an environmental protection standpoint, it is preferable that the volatile organic compound (VOC) value of the plasticizer used be low. When measured by thermogravimetric analysis, a value of less than 1000 ppm is preferred, less than 800 ppm is more preferred, less than 600 ppm is even more preferred, and less than 400 ppm is most preferred.

[0107] The content of the plasticizer is not particularly limited. It is preferably 0.1 to 20 parts by mass per 100 parts by mass of (meth)acrylic polymer (A), and more preferably 0.5 parts by mass or more, or 15 parts by mass or less. The lower and upper limits of the plasticizer content can be arbitrarily combined.

[0108] (Hydroxide tackifier) This adhesive composition may contain a hydrocarbon tackifier to impart hot-melt properties to the adhesive sheet. Examples of hydrocarbon tackifiers include terpene resins such as polyterpenes (e.g., α-pinene resins, β-pinene resins, and limonene resins) and aromatically modified polyterpene resins (e.g., phenol-modified polyterpene resins), coumaran-indene resins, petroleum 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 this adhesive composition.

[0109] The content of the hydrocarbon tackifier is not particularly limited. Preferably, it is 0.1 to 20 parts by mass per 100 parts by mass of (meth)acrylic polymer (A), and more preferably 0.5 parts by mass or more, or 15 parts by mass or less.

[0110] By including these plasticizers and hydrocarbon tackifiers, a suitable hot-melt adhesive composition with adhesive properties can be prepared.

[0111] <Method for preparing this adhesive composition> This adhesive composition can be obtained by mixing a (meth)acrylic polymer (A), and preferably further, a crosslinking agent (B), an initiator (C), and other components in predetermined amounts. The mixing method is not particularly limited, nor is the mixing order of the components particularly limited. Furthermore, a heat treatment step may be added during the manufacturing of this adhesive composition. In this case, it is desirable to mix each component of the adhesive composition beforehand before performing the heat treatment. A masterbatch made by concentrating various mixed components may also be used.

[0112] Furthermore, there are no particular restrictions on the equipment used for mixing; for example, a universal kneader, planetary mixer, Banbury mixer, kneader, gate mixer, pressure kneader, three-roll, or two-roll mixer can be used. A solvent may also be used for mixing as needed. Furthermore, this adhesive composition can be used as a solvent-free system. Using it as a solvent-free system offers the advantage of improved heat resistance and light resistance because no solvent remains.

[0113] <Layers other than the main adhesive layer> From the viewpoint of improving the storage stability, processability, and adhesive properties of the adhesive sheet, it is preferable that the adhesive sheet has a multi-layer structure of two or more layers. In such cases, it is preferable to have an intermediate layer as a layer other than the adhesive layer, and for example, the composition of the intermediate layer is arbitrary. However, from the viewpoint of further improving interlayer adhesion, it is preferable that the resin composition forming layers other than the adhesive layer also contains (meth)acrylic polymer (A) as a main component, and in particular, it is preferable that it contains the same (meth)acrylic polymer (A) as the adhesive layer as a main component. Furthermore, it is even more preferable that layers other than the adhesive layer also contain a crosslinking agent (B) and an initiator (C). In this case, it is even more preferable that the crosslinking agent (B) contains a polyfunctional (meth)acrylate (b-1).

[0114] If the adhesive sheet has a two-layer structure consisting of an outermost layer and an innermost layer, and the outermost and innermost layers have different hardnesses, it is possible to achieve both fluidity and storage stability, which are conflicting challenges, by functionally separating each layer. In other words, it is preferable to have a high-hardness layer to give the adhesive sheet rigidity, ensuring handling and storage stability, while having a flexible layer that can follow the irregularities of the adherend surface, such as bottomed holes. Furthermore, in the case of a three-layer structure comprising an outermost layer, an innermost layer, and an intermediate layer, if the intermediate layer and the outer and inner layers have different hardnesses, it is possible to achieve both fluidity and storage stability, which are conflicting challenges, by functionally separating each layer. In other words, it is preferable to have a high-hardness layer to give the adhesive sheet rigidity, ensuring handling and storage stability, while having a flexible layer that can follow the flow of irregularities on the adherend surface, such as bottomed holes. In particular, a configuration in which the intermediate layer has a higher hardness than the front and back layers is preferable because the flexible front and back layers can easily follow the irregularities of the adherend. When the adhesive sheet has a three-layer structure consisting of a front and back layer and an intermediate layer, the thickness ratio of each layer (outermost layer:intermediate layer:innermost layer) is preferably 1:0.5:1 to 1:10:1, more preferably 1:0.7:1 to 1:6:1, and particularly preferably 1:1:1 to 1:4:1.

[0115] This adhesive sheet has a tolerance of 10-500 mJ / cm². 2 It may be partially cured by irradiation with active energy rays. When irradiated with active energy rays from both sides, the total irradiation dose is the sum of the cumulative irradiation dose from one side and the cumulative irradiation dose from the other side. Partial curing refers to a state in which the material is slightly cross-linked while still having room for further curing; for example, in terms of gel fraction, it is a state of 0% to 50%. Because the adhesive sheet is pre-cured by irradiation with a small amount of active energy rays, particularly ultraviolet irradiation, it maintains high fluidity while also having good storage stability, whereas adhesive sheets with higher fluidity usually suffer from reduced storage stability. As mentioned above, there has been a demand for further improvements in the fluidity of adhesive sheets in recent years, but achieving both improved fluidity and reduced storage stability has become difficult. In this invention, it is preferable to cure the adhesive sheet by irradiation with a small amount of active energy rays in order to improve storage stability while maintaining high fluidity. Normally, it is thought that pre-irradiating with active energy rays would harden the adhesive sheet, causing problems such as a longer cycle time and a higher pore-filling temperature. However, when we deliberately tried irradiation with a small amount, we found that such problems did not occur, and it was possible to achieve both high fluidity and storage stability. Furthermore, if this adhesive sheet does not have high fluidity, it will have some degree of storage stability, and a small amount of irradiation is not necessary. If a small amount of irradiation were to be performed, it is thought that the fluidity would decrease, and the ability to conform to pores would decrease.

[0116] <How to use this adhesive sheet> This adhesive sheet can also be used as a standalone adhesive sheet. For example, the adhesive composition can be directly applied to a substrate to form a sheet, or the adhesive composition can be directly extruded or injected into a mold to use the adhesive sheet. Furthermore, the adhesive sheet can also be used by directly filling the spaces between components such as conductive members with the adhesive composition.

[0117] On the other hand, this adhesive sheet can also be used as a laminate of adhesive sheets with a release film, comprising this adhesive sheet and a release film. For example, the adhesive composition can be molded into a single-layer or multi-layer sheet on a release film to form an adhesive sheet with a release film.

[0118] Examples of materials for the release film include polyester film, polyolefin film, polycarbonate film, polystyrene film, acrylic film, triacetylcellulose film, and fluororesin film. Among these, polyester film and polyolefin film are particularly preferred.

[0119] The thickness of the release film is not particularly limited. However, from the viewpoint of processability and handling, for example, it is preferable that it be between 25 μm and 500 μm, and more preferably between 38 μm or more or 250 μm or less, and more preferably between 50 μm or more or 200 μm or less.

[0120] <This laminate> An example of an embodiment of the present invention is an image display device component laminate (referred to as "this laminate") which has a configuration in which this adhesive sheet is interposed between two image display device components, and the two image display device components are laminated via this adhesive sheet. This laminate can be bonded to two image display device components by irradiating the adhesive sheet with active energy rays, which causes the adhesive sheet to harden (the hardened adhesive sheet is referred to as the "hardened adhesive sheet").

[0121] In this case, the two image display device components include, at least one of which is a laminate consisting of one or more combinations of touch sensors, image display panels, surface protection panels, polarizing films, and phase difference films.

[0122] In particular, at least one of the two image display device components has a contact surface with the adhesive sheet with a depth (mm) / bottom area (mm 2 The ratio of ) is 1.0 × 10 -5 ~3.0×10 -1 , especially 5.0×10 -5 The above or 2.0 x 10 -1 Below, among them, 1.0 × 10 -4 The above or 1.0 × 10 -1 The adhesive sheet can be more effective if it has the following type of bottomed pore. In this case, the resin composition of the adhesive sheet can be filled into the bottomed hole, and the filling can be done so that there are no voids of at least 1 mm in diameter within the bottomed hole. The "diameter of the void" refers to the longest diameter when the void is non-spherical.

[0123] Specific examples of this laminate include configurations such as release film / this adhesive sheet or cured adhesive sheet / touch panel, image display panel / this adhesive sheet or cured adhesive sheet / touch panel, image display panel / this adhesive sheet or cured adhesive sheet / touch panel / this adhesive sheet or cured adhesive sheet / protective panel, polarizing film / this adhesive sheet or cured adhesive sheet / touch panel, and polarizing film / this adhesive sheet or cured adhesive sheet / touch panel / this adhesive sheet or cured adhesive sheet / protective panel.

[0124] The aforementioned touch panel includes structures in which a touch panel function is built into a protective panel, and structures in which a touch panel function is built into an image display panel. Therefore, the laminate may have a configuration such as release film / this adhesive sheet or cured adhesive sheet / protective panel, release film / this adhesive sheet or cured adhesive sheet / image display panel, or image display panel / this adhesive sheet or cured adhesive sheet / protective panel. Furthermore, the above-mentioned configurations include all configurations in which the conductive layer is interposed between the adhesive sheet or the cured adhesive sheet and adjacent components such as touch panels, protective panels, image display panels, and polarizing films. However, the examples of lamination are not limited to these.

[0125] The aforementioned touch panel can be of any type, such as resistive, capacitive, or electromagnetic induction. Among these, the capacitive type is preferred.

[0126] The material of the protective panel may be glass, or other plastics such as acrylic resin, polycarbonate resin, alicyclic polyolefin resin such as cycloolefin polymer, styrene resin, polyvinyl chloride resin, phenolic resin, melamine resin, or epoxy resin.

[0127] The image display panel consists of a polarizing film or other optical film such as a phase difference film, a liquid crystal material, and a backlight system (usually, the adhesive composition or adhesive article adheres to the image display panel as an optical film). Depending on the control method of the liquid crystal material, there are STN, VA, and IPS methods, and any of these methods may be used.

[0128] This 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.

[0129] <Manufacturing method for laminated structures for image display devices> Next, an example of a method for manufacturing this laminate will be described. However, the method for manufacturing this laminate is not limited to the method described below.

[0130] This laminate is formed by bonding this adhesive sheet to one side of a first image display device component to form a laminate, and then bonding the adhesive sheet of the bonded component to the bonded surface of a second image display device component, which has a bottomed hole on its bonded surface, facing each other and bonding them tightly under reduced pressure to form a laminate. Next, the laminate is subjected to a heat and pressure treatment to hot-melt the adhesive sheet, thereby allowing the adhesive composition to flow into the bottomed hole of the second image display device component. Finally, the adhesive sheet sandwiched between the first and second image display device components is irradiated with active energy rays to cure the adhesive sheet, thereby enabling the manufacturing process.

[0131] In this case, it is preferable to perform the heating and pressurizing treatment on the laminate by applying a pressure of 0.2 MPa to 0.8 MPa at a temperature of 40°C to 80°C. In particular, the above temperature is preferably 45°C or higher or 78°C or lower, and more preferably 50°C or higher or 75°C or lower. Furthermore, the above pressure is more preferably 0.25 MPa or higher or 0.75 MPa or lower, and more preferably 0.30 MPa or higher or 0.70 MPa or lower. Furthermore, the processing time, or in other words, the time for applying the pressure, is preferably 5 minutes or more, particularly preferably 5 minutes or more or 60 minutes or less, and even more preferably 10 minutes or more or 45 minutes or less.

[0132] In the present invention, ultraviolet light and visible light are preferred as the active energy rays in the above-mentioned active energy ray irradiation. Examples of light sources used when irradiating with active energy rays include high-pressure mercury lamps, low-pressure mercury lamps, metal halide lamps, xenon lamps, halogen lamps, LED lamps, fluorescent lamps, and electron beam irradiation devices. These can be selected according to the wavelength and amount of light to be irradiated. Furthermore, there are no particular limitations regarding irradiation time or irradiation method, but for example, if ultraviolet irradiation is used, the integrated light amount at a wavelength of 365 nm is 100 mJ / cm². 2 ~10000 mJ / cm 2 Preferably, and more preferably, 500 mJ / cm² 2 Above or above, or 8000 mJ / cm² 2 More preferably, 1000 mJ / cm² 2 Above or above, or 6000 mJ / cm² 2 The following is particularly preferred: 1500 mJ / cm² 2 Above or above, or 4000 mJ / cm² 2 The following applies: Furthermore, when ultraviolet light is irradiated from both sides, the accumulated light quantity is the sum of the accumulated light quantity from one side and the accumulated light quantity from the other side.

[0133] A preferred example of this laminate is an image display device component laminate comprising two image display device components laminated via a post-cured adhesive sheet having a thickness of 0.8 to 1.5 mm, wherein the creep strain after curing at 80°C for 180 seconds under predetermined curing conditions is 10% or more. The post-cured adhesive sheet is the sheet after the adhesive sheet has been cured. In this case, at least one of the image display device components has a contact surface with the adhesive sheet, as described above, with a depth (mm) / bottom area (mm). 2 ) is 1.0 × 10 -5 ~3.0×10 -1 Examples include those having a bottomed hole. In this case, the bottomed hole is filled with the aforementioned hardened adhesive sheet, and it is preferable that there are no voids of at least 1 mm in diameter within the bottomed hole. Furthermore, the "diameter of the void" refers to the longest diameter when the void is non-spherical.

[0134] <This image display device> An example of an embodiment of the present invention (also referred to as "this image display device") is an image display device equipped with a laminate for the configuration of this image display device. Specific examples of this image display device include liquid crystal displays, organic EL displays, inorganic EL displays, electronic paper, plasma displays, and microelectromechanical systems (MEMS) displays.

[0135] <Explanation of terms> In this invention, when expressed as "X~Y" (where X and Y are any numbers), unless otherwise specified, it includes the meaning of "greater than or equal to X and less than or equal to Y," as well as the meaning of "preferably greater than X" or "preferably less than Y." Furthermore, when we use expressions like "greater than or equal to X" (where X is any number) or "less than or equal to Y" (where Y is any number), we also imply that "greater than X is preferable" or "less than Y is preferable." Furthermore, in this invention, "sheet" conceptually encompasses sheets, films, and tapes. [Examples]

[0136] The present invention will be further explained below with reference to examples and comparative examples. However, the present invention is not limited to these examples.

[0137] <(meth)acrylic polymer> • (Meth)acrylic polymer A-1: ​​Acrylic graft copolymer (weight average molecular weight: 160,000, glass transition temperature: -36°C) obtained by copolymerizing 15 parts by mass of polymethyl methacrylate macromonomer with a number average molecular weight of 2400 (glass transition temperature 105°C), 81 parts by mass of butyl acrylate (glass transition temperature -55°C), and 4 parts by mass of acrylic acid (glass transition temperature 106°C). • (Meth)acrylic polymer A-2: Acrylic graft copolymer (weight average molecular weight: 300,000, glass transition temperature: -45°C) obtained by copolymerizing 6 parts by mass of polymethyl methacrylate macromonomer with a number average molecular weight of 2400 (glass transition temperature 105°C), 90 parts by mass of butyl acrylate (glass transition temperature -55°C), and 4 parts by mass of acrylic acid (glass transition temperature 106°C). • (Meth)acrylic polymer A-3: Acrylic graft copolymer (weight-average molecular weight: 300,000, glass transition temperature: -42°C) obtained by copolymerizing 9 parts by mass of polymethyl methacrylate macromonomer with a number-average molecular weight of 2400 (glass transition temperature 105°C), 87 parts by mass of butyl acrylate (glass transition temperature -55°C), and 4 parts by mass of acrylic acid (glass transition temperature 106°C). • (Meth)acrylic polymer A-4: An acrylic copolymer obtained by copolymerizing 64 parts by mass of 2-ethylhexyl acrylate (glass transition temperature -70°C), 19 parts by mass of methyl acrylate (glass transition temperature 10°C), and 17 parts by mass of hydroxyethyl acrylate (glass transition temperature -15°C) (weight-average molecular weight: 540,000, glass transition temperature -50°C).

[0138] The glass transition temperatures of each copolymer component in the above (meth)acrylic polymers are the literature values ​​for the glass transition temperatures obtained from homopolymers of the respective components. For macromonomers, the literature values ​​for the glass transition temperatures obtained from homopolymers of the components forming the high molecular weight skeleton within the macromonomer are listed. The glass transition temperature of a (meth)acrylic copolymer is a value calculated using Fox's formula based on the glass transition temperatures and composition ratios of each copolymer component.

[0139] <Crosslinking agent> • Crosslinking agent B-1: Propoxylated pentaerythritol triacrylate (glass transition temperature when homopolymerized: 62°C) Crosslinking agent B-2: 1,9-nonanediol diacrylate (glass transition temperature when homopolymerized: 38°C) Crosslinking agent B-3: Polytetramethylene glycol diacrylate (glass transition temperature when homopolymerized: -60°C) Crosslinking agent B-4: Mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate

[0140] The glass transition temperature of the above crosslinking agent when it is in the form of a homopolymer was measured as follows. To 100 g of the above crosslinking agent, 1 g of a photopolymerization initiator (IGM's "Esacure TZT") was added to obtain a mixture of the crosslinking agent and the photopolymerization initiator. A silicone resin sheet frame with an opening measuring 4 mm wide, 37 mm long, and 0.6 mm thick was laminated onto a 0.55 mm thick soda-lime glass, and the mixture was poured into the frame. Another 0.55 mm thick soda-lime glass was placed on top, and ultraviolet light with an integrated light intensity of 4000 mJ / cm² at 365 nm was applied. 2 The crosslinking agent was cured by irradiating it from both sides through soda-lime glass, thereby producing a homopolymer composed of the crosslinking agent. The prepared samples were subjected to dynamic viscoelasticity measurements using a viscoelasticity analyzer (DVA-200, manufactured by IT Measurement Control Co., Ltd.) under the conditions of frequency 1 Hz, heating rate: 3 °C / min, and measurement temperature -70 °C to 130 °C. The peak temperature of Tanδ obtained from the viscoelasticity curve was defined as the glass transition temperature (Tg).

[0141] <Initiator> • Photopolymerization initiator C-1: A mixture of 2,4,6-trimethylbenzophenone and 4-methylbenzophenone (IGM's "Esacure TZT") • Photopolymerization initiator C-2: Ethyl phenyl (2,4,6-trimethylbenzoyl) phosphinate (IGM's "Omnirad TPO-L")

[0142] <Other ingredients> • Rust inhibitor (D-1): 1,2,3-benzotriazole • Silane coupling agent (E-1): 3-glycidoxypropyltrimethoxysilane

[0143] [Example 1] 100 parts by mass of (meth)acrylic polymer A-2, 3 parts by mass of crosslinking agent B-3, 2.5 parts by mass of photopolymerization initiator C-1, and 0.5 parts by mass of rust inhibitor were prepared and used as raw materials for the adhesive layer. On the other hand, 100 parts by mass of (meth)acrylic polymer A-1, 3 parts by mass of crosslinking agent B-2, and 2.5 parts by mass of photopolymerization initiator C-1 were prepared and used as raw materials for the intermediate layer. The raw materials for the adhesive layer and the intermediate layer were supplied to two extruders, respectively, and co-extruded in a 2-type, 3-layer configuration (adhesive layer / intermediate layer / adhesive layer, thickness 1:1:1) to obtain an adhesive sheet.

[0144] Next, the adhesive sheet was sandwiched between two polyethylene terephthalate films with a release surface treatment (Mitsubishi Chemical's "Diafol MRV (V06)", 100 μm thick, and Mitsubishi Chemical's "Diafol MRQ", 75 μm thick), i.e., two release films, and hot-melt molded into a sheet with a thickness of 150 μm, thereby obtaining an adhesive sheet laminate consisting of release film / adhesive sheet 1 / release film. When the integrated light intensity at a wavelength of 365 nm is applied to such adhesive sheet laminate from both sides, it reaches 200 mJ / cm². 2 (The cumulative light intensity on one side is 100 mJ / cm²) 2 The total is 200 mJ / cm². 2 The material was slightly hardened by irradiating it with light from a high-pressure mercury lamp to create an adhesive sheet. Furthermore, adhesive sheet 1 was in a partially cured state and was a photocurable adhesive sheet that hardened when exposed to light.

[0145] [Example 2] ~4、6~ 10. Comparative Examples 1-2] As shown in Tables 1 and 2, the adhesive sheets 2~ were used in the same manner as in Example 1, except that the composition of each layer, the layer configuration, and the amount of ultraviolet irradiation were changed. 4 and 6~ 12 and adhesive sheet laminate 2~ 4 and 6~ I created 12. Note: Adhesive sheet 2~ 4 Materials 8-10 were in a partially cured state and were adhesive sheets with photocuring properties that would harden upon exposure to light. Adhesive sheets 6, 7, 11, and 12 were in an uncured state and were photocurable adhesive sheets that hardened when exposed to light.

[0146] [Physical property measurement and evaluation] Adhesive sheets 1~ prepared in the above examples and comparative examples 4 and 6~Regarding item 12, the following various measurements and evaluations were performed. The evaluation results are summarized in Tables 1 and 2.

[0147] <Creep test> (Pre-hardening creep) Multiple adhesive sheets prepared in the examples and comparative examples were used and laminated to a thickness of 0.8 to 1.5 mm, and then punched out in a circular shape with a diameter of 8 mm. Using a rheometer (TA Instruments "DHR-2"), the strain (%) after 3600 seconds was measured with a measurement jig: 8mm diameter parallel plate, temperature: 25°C, pressure: 1000Pa, torque: 100μN·m.

[0148] (Creep after full hardening) The adhesive sheets prepared in the examples and comparative examples were subjected to a high-pressure mercury lamp with an integrated light intensity of 3000 mJ / cm² at 365 nm. 2 To achieve this, the adhesive sheet was cured by irradiating it with ultraviolet light through a peel-treated polyethylene terephthalate film. However, for the adhesive sheet of Comparative Example 3, the ultraviolet light was applied with an integrated light intensity of 4000 mJ / cm² at 365 nm. 2 The adhesive sheet was fully cured by irradiating it in this manner. The fully cured adhesive sheets were layered to a thickness of 0.8 to 1.5 mm, and then punched out in a circular shape with a diameter of 8 mm to create the final product. Using a rheometer (TA Instruments "DHR-2"), the strain (%) after 180 seconds was measured with a measurement jig: 8mm diameter parallel plate, temperature: 80°C, pressure: 1000Pa, torque: 100μN·m.

[0149] <Hollowing properties (fluidity)> A polyethylene terephthalate film with an adhesive layer (total thickness 125 μm) was prepared by laminating a 25 μm thick double-sided adhesive sheet onto one side of a 100 μm thick polyethylene terephthalate film (Toyobo Co., Ltd.'s "Cosmoshine A4300") using a hand roll. The polyethylene terephthalate film with the adhesive layer was cut to 54 mm x 82 mm, and cylindrical closed holes with a diameter of 4 mm were made at the four corners of the cut film, with a distance of 6 mm from the edge to the center of the hole. Depth (mm) / bottom area (mm) of these closed holes 2 ) is 9.95 × 10 -3 That was the case. A substrate for evaluating pore-filling properties was prepared by roll-laminating the aforementioned film onto a 54mm x 82mm, 0.55mm thick soda-lime glass, resulting in four bottomed pores with a diameter of 4mm and a depth of 125μm.

[0150] In the examples and comparative examples, one release film was peeled off the adhesive sheet laminate, and the exposed adhesive surface was roll-pressed onto soda-lime glass (82 mm × 54 mm × 0.55 mm thick). Next, the remaining release film was peeled off, and the exposed adhesive surface was placed facing the side of the pore-filling performance evaluation substrate that has a bottomed hole, and pressed together using a vacuum laminating machine under reduced pressure (absolute pressure 2 kPa). The laminate was then heated and pressurized using an autoclave (60°C, gauge pressure 0.45 MPa, 20 minutes) to produce a pore-filling performance evaluation laminate.

[0151] The laminates were visually inspected, and those in which one or more voids with a diameter of 1 mm or more were observed inside the bottomed holes were classified as "poor," while those in which no such voids were observed were classified as "good." In the case of non-spherical voids, the diameter of the void was determined to be the longest diameter.

[0152] <Reliability (Reliability against foaming)> A polarizing plate with an adhesive layer (70 mm × 150 mm) having a thickness of 84 μm and a bottomed hole with a diameter of 4 mm was roll-laminated onto a 75 mm × 160 mm, 0.55 mm thick soda-lime glass sheet to prepare a substrate for reliability evaluation.

[0153] One of the release films of the adhesive sheet laminates prepared in the examples and comparative examples was peeled off, and the exposed adhesive surface was roll-pressed onto soda-lime glass (75 mm × 160 mm × 0.55 mm thick). Next, the remaining release film was peeled off, and the exposed adhesive surface was placed facing the side of the reliability evaluation substrate with a bottomed hole, and pressed together under reduced pressure (absolute pressure 2 kPa) using a vacuum laminating machine. After heating and pressurizing in an autoclave (60°C, gauge pressure 0.45 MPa, 20 minutes), ultraviolet light at 365 nm with an integrated intensity of 3000 mJ / cm² was applied through soda-lime glass. 2 The adhesive sheet was cured by irradiation to achieve the desired result, and a sample for reliability evaluation was prepared. However, for the adhesive sheet 7 of Comparative Example 2, ultraviolet light was irradiated through soda-lime glass to achieve an integrated light intensity of 4000 mJ / cm² at 365 nm. 2 The adhesive sheet was cured by irradiating it in this manner, and it was used as a sample for reliability evaluation.

[0154] This reliability evaluation sample was placed in a heat cycle tester and subjected to 200 cycles of 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.

[0155] After storage, the reliability evaluation samples were visually inspected. Samples with no bubbles visible in the pores were judged as "good," samples with one bubble less than 500 μm in diameter were judged as "fair," and samples with one bubble 500 μm or larger in diameter or two or more bubbles were judged as "poor." In the case of non-spherical bubbles, the diameter was determined by the longest diameter.

[0156] <Storage stability (evaluated by retention capacity)> Storage stability was determined by evaluating the retention capacity as follows. The adhesive sheets of the adhesive sheet laminates prepared in the examples and comparative examples were cut to 50 mm x 50 mm, the release film on one side was peeled off, and a polyethylene terephthalate film for backing (Mitsubishi Chemical Corporation, Diafoil S-100, 38 μm thick) was attached using a hand roller. This was then cut into strips 25 mm wide x 100 mm long. Next, the remaining release film was peeled off, and one end of the adhesive sheet was attached to a stainless steel plate (120mm x 50mm x 1.2mm thick) using a hand roller so that the adhesive area was 25mm x 20mm to create a test specimen. After curing the test specimen in a 40°C environment for 15 minutes, a 500gf (4.9N) weight was attached vertically to the other end of the adhesive sheet and left to stand. After 10 minutes, the length (mm) by which the adhesive sheet's position relative to the stainless steel plate had shifted downwards, i.e., the amount of displacement, was measured. A displacement of less than 2mm was judged as "good," and a displacement of 2mm or more was judged as "poor."

[0157] [Table 1] TIFF0007897252000002.tif252136

[0158] [Table 2]

[0159] <Gel fraction> (Gel fraction in the partially cured state) For Examples 1, 2, 3, 9, and 10, which are partially cured adhesive sheets, the gel fraction was measured as follows. The release film was removed from each adhesive sheet laminate, and these were used as samples. The sample was wrapped in a 150-mesh stainless steel wire mesh and immersed in ethyl acetate for 24 hours. It was then dried at 75°C for 4.5 hours. The mass of the adhesive was measured before and after ethyl acetate immersion, and the difference between the two weights was considered the weight of the insoluble adhesive remaining in the wire mesh. The percentage of the insoluble adhesive remaining in the wire mesh relative to the mass of the adhesive before ethyl acetate immersion was calculated as the gel fraction (X0) (%) in the partially cured state. The results are shown in Table 3. Samples with a gel fraction of 1% or less are indicated as "<1" in the table.

[0160] (Gel fraction in the fully cured state) The adhesive sheets prepared in Examples 1, 2, 3, 9, and 10 were subjected to a high-pressure mercury lamp, and the integrated light intensity at 365 nm was 3000 mJ / cm². 2 To achieve this, ultraviolet light is irradiated from both sides through the release film (the cumulative light intensity on one side is 1500 mJ / cm²). 2 That totals 3000 mJ / cm² 2 The adhesive sheet was then fully cured. The release film was removed from each adhesive sheet laminate, and these were used as samples. The sample was wrapped in a 150-mesh stainless steel wire mesh and immersed in ethyl acetate for 24 hours. It was then dried at 70°C for 4.5 hours. The mass of the adhesive was measured before and after ethyl acetate immersion, and the difference between the two weights was considered the weight of the insoluble adhesive remaining in the wire mesh. The mass percentage of the insoluble adhesive remaining in the wire mesh relative to the mass of the adhesive before ethyl acetate immersion was calculated as the gel fraction (X1) (%) in the cured state. The results are shown in Table 3.

[0161] [Table 3]

[0162] From the above examples and the test results conducted by the inventors to date, it is possible to hot-melt an adhesive sheet formed from an adhesive resin composition containing (meth)acrylic polymer (A) by applying heat and pressure treatment, provided that the sheet exhibits a predetermined amount of displacement and a predetermined creep strain before and after curing, thereby achieving excellent fluidity. Therefore, the hot-melted adhesive composition can be applied to pores present on the surface (adhesive surface) of the adherend, for example, in the area between the depth (mm) and bottom area (mm). 2 ) is 1.0 × 10 -5 ~3.0×10 -1It was found that the adhesive can flow into the bottomed holes and fill them completely without leaving any voids. Furthermore, it was found that the adhesive sheet of the present invention has good storage stability in addition to the above-mentioned fluidity. It was also found that even if the adherend changes size after the adhesive sheet has hardened, it is possible to prevent the adhesive filling the holes from foaming.

[0163] Comparative Example 1 exhibited significant displacement due to its holding strength before full curing, resulting in problems with adhesive leakage during storage. Comparative Example 2 exhibited a creep strain of 40% or less after 3600 seconds at 25°C before full curing. However, it could not completely fill the bottomed holes when poured in, and voids were observed within the holes, making it impractical. Furthermore, Comparative Example 2 exhibited a creep strain of 10% or less after 180 seconds at 80°C after full curing. In reliability tests, voids were observed within the bottomed holes, also making it impractical.

Claims

1. An active energy ray curable adhesive sheet comprising an adhesive layer formed from an adhesive composition containing a (meth)acrylic polymer (A), a crosslinking agent (B), and an initiator (C), The (meth)acrylic polymer (A) is the component with the highest mass percentage among the components constituting the adhesive composition, and the mass percentage of the (meth)acrylic polymer (A) is 50% by mass or more of the components constituting the adhesive composition. The crosslinking agent (B) comprises a polyfunctional (meth)acrylate component (b-1) having two or more (meth)acryloyl groups, The crosslinking agent (B) content is 0.2 parts by mass or more and 30 parts by mass or less per 100 parts by mass of (meth)acrylic polymer (A). The content of initiator (C) is 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of (meth)acrylic polymer (A). The aforementioned active energy ray-curable adhesive sheet exhibits a displacement of less than 2 mm in the following (1) holding strength test: When the thickness is 0.8 to 1.5 mm, the creep strain after 3600 seconds at 25°C before curing is between 40% and 1500%. An active energy ray curable adhesive sheet in which the creep strain after curing under the following curing conditions (2) at 80°C for 180 seconds is 10% or more. (1) Holding power test: An active energy ray curable adhesive sheet (25 mm wide x 100 mm long, in strip form) with polyethylene terephthalate film attached to one side is attached to a stainless steel plate (120 mm x 50 mm x 1.2 mm thick) using a hand roller to create a test specimen with an adhesive area of ​​25 mm x 20 mm. The test specimen is cured in a 40°C environment for 15 minutes, and then a 500 gf (4.9 N) weight is attached vertically to the other end of the adhesive sheet and left to stand. After 10 minutes, the length (mm) by which the adhesive sheet has shifted downward relative to the stainless steel plate is measured. (2) Curing conditions: 3000-4000 mJ / cm² under 365 nm ultraviolet light. ２ The process involves curing the substance by irradiating it with an accumulated amount of light within a certain range.

2. The active energy ray curable adhesive sheet according to claim 1, wherein the thickness of the adhesive sheet is 10 to 500 μm.

3. The active energy ray curable adhesive sheet according to claim 1, having a multi-layer structure of two or more layers.

4. The active energy ray curable adhesive sheet according to claim 1, wherein the (meth)acrylic polymer (A) is a block copolymer and / or a copolymer containing structural units derived from macromonomers as branch components.

5. The active energy ray curable adhesive sheet according to claim 1, wherein the (meth)acrylic polymer (A) is a copolymer containing structural units derived from macromonomers as branch components, and the copolymerization ratio of macromonomers is 1 to 10% by mass.

6. 10~500mJ / cm ２ The active energy ray curable adhesive sheet according to claim 1, which is an adhesive sheet that has been partially cured by irradiation with active energy rays.

7. The active energy ray curable adhesive sheet according to claim 1, wherein, when the thickness is 0.8 to 1.5 mm, the creep strain after 3600 seconds at 25°C before curing is 50% or more and 1500% or less.

8. A laminated adhesive sheet with a release film, comprising a structure in which an active energy ray-curable adhesive sheet according to any one of claims 1 to 7 and a release film are laminated together.

9. An active energy ray-curable adhesive sheet obtained by curing an active energy ray-curable adhesive sheet according to any one of claims 1 to 7.

10. A laminate for an image display device, having a configuration in which two image display device components are laminated together with an adhesive sheet in between, The adhesive sheet is an adhesive composition comprising a (meth)acrylic polymer (A), a crosslinking agent (B), and an initiator (C), The (meth)acrylic polymer (A) is the component with the highest mass percentage among the components constituting the adhesive composition, and the mass percentage of the (meth)acrylic polymer (A) is 50% by mass or more of the components constituting the adhesive composition. The crosslinking agent (B) comprises a polyfunctional (meth)acrylate component (b-1) having two or more (meth)acryloyl groups, and the content of the crosslinking agent (B) is 0.2 parts by mass or more and 30 parts by mass or less per 100 parts by mass of (meth)acrylic polymer (A), and The adhesive layer is formed from an adhesive composition in which the initiator (C) is present in an amount of 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of (meth)acrylic polymer (A). This is an active energy ray curable adhesive sheet with a thickness of 0.8 to 1.5 mm, wherein the creep strain after 3600 seconds at 25°C before curing is 40% or more and 1500% or less, and the creep strain after 180 seconds at 80°C under the following curing conditions is 10% or more. At least one of the image display device components has a contact surface with the adhesive sheet, with a depth (mm) / bottom area (mm). ２ ) is 1.0 × 10 －５ ~3.0 x 10 －１ A laminate for an image display device, characterized by having a bottomed hole. Curing conditions: 3000-4000 mJ / cm² under 365 nm ultraviolet light. ２ The process involves curing the substance by irradiating it with an accumulated amount of light within a certain range.

11. The aforementioned adhesive sheet has a flow rate of 10 to 500 mJ / cm². ２ The laminate for an image display device according to claim 10, which is an adhesive sheet that has been partially cured by irradiation with active energy rays.

12. The laminate for an image display device according to claim 10, wherein the image display device component consists of one or more combinations of the group consisting of a touch panel, an image display panel, a surface protection panel, a polarizing film, and a phase difference film.

13. An image display device configured using the laminate for image display device configuration described in any one of claims 10 to 12.

14. A method for manufacturing a laminate for an image display device, comprising a configuration in which two image display device components are laminated via a cured adhesive sheet of an active energy ray curable adhesive sheet as described in any one of claims 1 to 7, The adhesive sheet is attached to one side of the first image display device component to form a laminated body, and the adhesive sheet of the laminated body is placed facing the surface to be attached of the second image display device component, which has a bottomed hole on the surface to be attached, and is laminated by pressing them together under reduced pressure to form a laminated body. By applying heat and pressure treatment to the laminate to hot-melt the adhesive sheet, the adhesive composition is allowed to flow into the bottomed hole of the second image display device component. A method for manufacturing a laminate for an image display device, characterized by curing the adhesive sheet, which is sandwiched between the first and second image display device members, by irradiating the adhesive sheet with active energy rays.

15. The bottomed hole of the second image display device component has a depth (mm) / bottom area (mm ２ ) of 1.0×10 －５ to 3.0×10 －１ The method for manufacturing a laminate for an image display device according to claim 14, characterized in that it is as described above.

16. The method for manufacturing a laminate for an image display device according to claim 14, wherein the cured adhesive sheet has a thickness of 0.8 to 1.5 mm and exhibits a creep strain of 10% or more after 180 seconds at 80°C.

17. The method for manufacturing a laminate for an image display device according to claim 14, characterized in that the heat and pressurization treatment of the laminate is performed by applying a pressure of 0.2 MPa to 0.8 MPa to the laminate at a temperature of 40°C to 80°C.

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