Adhesive sheet with release film

Abstract

To provide an adhesive sheet having an adhesive surface having high surface smoothness.SOLUTION: An adhesive sheet with a release film is provided which comprises: an adhesive sheet; and a release film laminated on an adhesive surface of the adhesive sheet. The maximum height Rz of the adhesive surface-side surface of the release film of the adhesive sheet with the release film is 400 nm or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an adhesive sheet with a release film.

Background Art

[0002] Generally, an adhesive (also referred to as a pressure-sensitive adhesive. The same applies hereinafter) exhibits a state of a soft solid (viscoelastic body) in a temperature range near room temperature and has the property of easily adhering to an adherend by pressure. Taking advantage of this property, adhesives are widely used in various industrial fields such as home appliances, automobiles, and OA equipment, typically in the form of an adhesive sheet including a layer of the adhesive.

[0003] Among the above-mentioned adhesive sheets, there are those that require a high degree of smoothness on the adhesive surface (the surface of the adhesive layer). As an example of such an adhesive sheet, an adhesive sheet for optical applications can be mentioned. For example, Patent Documents 1 and 2 describe setting the surface roughness (Ra) of the adhesive layer of an optical adhesive sheet within a predetermined range for the purpose of improving visibility. Patent Document 3 describes setting the ten-point average roughness of the adhesive surface of an adhesive sheet that can be used for optical applications to about 1000 nm or less. Furthermore, Patent Document 4 describes setting the surface roughness (Ra) of the release film disposed on the surface of the adhesive layer of an adhesive sheet to be pasted on an optical member such as a polarizing plate to 0.1 μm or less. Patent Document 5 describes setting the surface roughness (Ra) and the maximum protrusion height (Rp) of the release film within a predetermined range.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

[0005] In various products such as portable electronic devices, adhesive sheets can be used in areas that are visible from the outside. For example, adhesive sheets for portable electronic devices can be used not only on the image display surface of the device, but also on other surfaces (e.g., the back surface). Therefore, adhesive sheets used in this application are sometimes required to have high transparency so as not to be noticeable, and in addition, their adhesive surface may require high smoothness. If there are orange peel textures or streaks on the adhesive surface, visibility through the adhesive sheet will decrease, and the design, aesthetics, and sense of luxury of the adherend surface may be impaired.

[0006] While not particularly limited, one application where a highly smooth adhesive surface is desirable is the application of a film with a metallic or other specific color tone to the inside of a transparent casing that constitutes a portable electronic device, with the decorative side facing the transparent casing. For the adhesive sheet used to fix the transparent casing and the film, it is desirable that both adhesive surfaces have high smoothness, as both can affect visibility. Even adhesive sheets that previously met acceptable smoothness standards may exhibit optical distortion under more precise evaluation conditions, meaning they do not necessarily possess a satisfactory level of surface smoothness. Realizing an adhesive sheet with a higher level of smoothness would be practically beneficial as a bonding method that does not impair the design, aesthetics, or premium feel of the adherend.

[0007] This invention was created in view of the above circumstances, and aims to provide an adhesive sheet having an adhesive surface with high surface smoothness, protected by a release film. [Means for solving the problem]

[0008] This specification provides an adhesive sheet with a release film. This adhesive sheet with a release film comprises an adhesive sheet having an adhesive layer and a release film laminated on the adhesive surface of the adhesive sheet. Furthermore, the maximum height Rz of the adhesive surface side of the release film is 400 nm or less. According to the above configuration, the adhesive surface of the adhesive sheet is protected by the release film while in contact with the release film surface, which has a maximum height Rz of 400 nm or less, and therefore has high surface smoothness. Consequently, when attached to an object, the adhesive surface with the object has high surface smoothness, and adhesion with no optical distortion or suppressed optical distortion can be achieved.

[0009] In some preferred embodiments, the arithmetic mean roughness Ra of the surface of the release film is 30 nm or less. This configuration preferably provides an adhesive surface with high surface smoothness.

[0010] In some preferred embodiments, the peeling force of the release film from the adhesive sheet is 1 N / 50 mm or less. With this configuration, when the release film is removed from the adhesive surface during use of the adhesive sheet, the fine waviness of the adhesive surface caused by the so-called stick-slip phenomenon resulting from peeling from the release film is suppressed, making it easier to obtain a smoother adhesive surface.

[0011] In some preferred embodiments, the thickness of the release film is in the range of 50 to 125 μm. With this configuration, the release film has sufficient thickness, preventing phenomena such as impairing the smoothness of the adhesive sheet surface through the release film (dents). Such phenomena may be caused, for example, by foreign matter mixed in between the release film when winding the adhesive sheet with the release film onto a roll. Furthermore, by setting the thickness of the release film to below a predetermined value, removal from the adhesive sheet becomes smoother, and the adhesive surface of the adhesive sheet is more likely to maintain high surface smoothness even after the release film is removed.

[0012] In some preferred embodiments, the total light transmittance of the adhesive sheet is 85% or more, and the haze value is 1% or less. An adhesive sheet satisfying the above characteristics allows the adherend to be easily seen through the adhesive sheet and does not impair the visibility of the design or other features of the adherend.

[0013] In some embodiments, the adhesive sheet is a single-sided adhesive sheet having an adhesive layer and a support substrate laminated on one side of the adhesive layer. The effects of the technology disclosed herein can preferably be realized in embodiments using a single-sided adhesive sheet. In this embodiment, the support substrate may be a transparent substrate.

[0014] In some other embodiments, the adhesive sheet is a double-sided adhesive sheet having a first adhesive surface and a second adhesive surface. The adhesive sheet with a release film also includes a release film consisting of a first release film disposed on the first adhesive surface and a second release film disposed on the second adhesive surface. The maximum height Rz1 of the first release film's surface S1 on the first adhesive surface and the maximum height Rz2 of the second release film's surface S2 on the second adhesive surface are both 400 nm or less. Even in such configurations, the effects of the disclosed technology can be favorably realized. In this configuration, the arithmetic mean roughness Ra1 of the surface S1 of the first release film and the arithmetic mean roughness Ra2 of the surface S2 of the second release film are both preferably 30 nm or less. Furthermore, the peeling force of the first release film to the adhesive sheet and the peeling force of the second release film to the adhesive sheet may both be 1 N / 50 mm or less. Additionally, the thickness of the first release film and the thickness of the second release film may each be within the range of 50 to 125 μm.

[0015] In several other embodiments, the adhesive sheet is a double-sided adhesive sheet having a first adhesive surface and a second adhesive surface. The release film is a double-sided release film having a first release surface and a second release surface. The maximum height Rz1 of the first release surface and the maximum height Rz2 of the second release surface of the release film are both 400 nm or less. Even in such configurations, the effects of the technology disclosed herein can be preferably realized. In this configuration, the arithmetic mean roughness Ra1 of the first release surface and the arithmetic mean roughness Ra2 of the second release surface are both preferably 30 nm or less. The peeling force of the first release surface to the adhesive sheet and the peeling force of the second release surface to the adhesive sheet may both be 1 N / 50 mm or less.

[0016] In some preferred embodiments, the adhesive layer is an acrylic adhesive layer. With an acrylic adhesive, it is possible to achieve the target adhesive properties and viscoelastic properties with excellent impact resistance without using additive components such as softeners that may cause a decrease in transparency, or by limiting the amount of additives used, thus making it easier to achieve both transparency and adhesive and viscoelastic properties. In addition, acrylic adhesives tend to have better discoloration resistance compared to rubber-based adhesives, for example, and are advantageous in terms of maintaining transparency over a long period of time.

[0017] In some preferred embodiments, the gel fraction of the adhesive layer is 30 to 95% by weight. When the gel fraction of the adhesive layer is 95% by weight or less, the adhesive sheet tends to have excellent conformability to uneven surfaces. Therefore, it can adhere well to the surface of an object having steps. For example, when a logo or the like is printed on the surface of the object, the adhesive sheet can conform well to the unevenness of the print without impairing visibility. Furthermore, when the gel fraction of the adhesive layer is 30% by weight or more, it tends to exhibit good adhesive properties and viscoelastic properties. For example, a configuration having an adhesive layer with the above gel fraction tends to be less prone to dents and also exhibits excellent deformation resistance.

[0018] In some preferred embodiments, the storage modulus of the adhesive layer at 25°C is 4 × 10⁻⁶. 4 The storage modulus at 25°C is Pa or higher. The adhesive layer having the above 25°C storage modulus tends to have desirable heat resistance and easily exhibits good adhesive properties such as deformation resistance.

[0019] In some preferred embodiments, the thickness of the adhesive sheet is 5 to 100 μm. Adhesive sheets with a thickness of 5 μm or more tend to have excellent conformability to uneven surfaces and easily absorb deformation caused by foreign matter. Furthermore, by setting the thickness to 100 μm or less, the adhesive sheet is less prone to distortion and high adhesive surface smoothness can be easily obtained.

[0020] In some preferred embodiments, the adhesive sheet has an elastic modulus of 3.0 MPa or higher, as measured by the tensile test described below. By satisfying the above characteristics, the adhesive sheet can exhibit high deformation resistance. [Tensile test] The adhesive layer of the aforementioned adhesive sheet is exposed to an illuminance of 300 mW / cm². 2 , cumulative light intensity 3000 mJ / cm 2 The adhesive layer is irradiated with ultraviolet light under the specified conditions and aged at 50°C for 48 hours. After this, the adhesive layer is cut to a size of 10 mm in width and 150 mm in length to prepare a test specimen. In an environment of 23°C and 50% RH, a tensile test is performed on the test specimen using a tensile testing machine with a chuck distance of 120 mm and a tensile speed of 50 mm / min to obtain a stress-displacement curve, and the modulus of elasticity [MPa] is calculated from its initial slope.

[0021] In some preferred embodiments, the adhesive sheet has an impact resistance of 2.0 J / 10 mm² as measured by the following shear impact test. 2 This concludes the explanation. By satisfying the above characteristics, the adhesive sheet can exhibit high impact resistance. For example, an adhesive sheet that satisfies the elastic modulus characteristics determined by the tensile test and the above impact resistance characteristics can form a joint that is highly resistant to deformation and impact, and can therefore be preferably used for purposes such as joining and fixing members. [Shear impact test] A shear impact test will be performed using a pendulum-type adhesive shear impact tester based on JIS K6855. For the measurement sample, the first side of the 10 mm square adhesive sheet will be attached to the center of a 25 mm square, 1.7 mm thick chemically strengthened glass plate, and then the second side of the adhesive sheet will be attached to the center of a 40 mm square stainless steel plate (SUS304BA plate). The samples will be pressed together with a load of 5 N for 10 seconds, followed by autoclaving (50°C, 0.5 MPa, 15 minutes), and an illuminance of 300 mW / cm² will be applied from the glass plate side. 2 , cumulative light intensity 3000 mJ / cm 2 The product used will have been irradiated with ultraviolet light under these conditions, followed by aging at 50°C for 48 hours. The measurement sample is fixed with the stainless steel plate facing downwards, and the absorbed energy [J] is measured when a hammer is struck against the outer surface of the glass plate under the conditions of hammer energy 2.75J and hammer speed 3.5m / sec in an environment of 23℃ and 50%RH, thereby determining the impact resistance [J / 10mm]. 2 Find the answer to ].

[0022] In some preferred embodiments, the adhesive layer contains a polymer (A) and a photoreactive monomer (B). The photoreactive monomer (B) contains a compound B1 having a ring structure and two or more ethylenically unsaturated groups in its molecule, and it is more preferable that the molecular weight of compound B1 per ethylenically unsaturated group is 100 g / mol or more. An adhesive sheet having the above adhesive layer can suitably form a bond with high deformation resistance and high impact resistance.

[0023] The adhesive sheet with release film disclosed herein can be made to have an adhesive sheet with high surface smoothness on both adhesive surfaces, and is therefore preferably used in applications for fixing transparent members to members having an image display surface, decorative surface, or colored surface, where high visibility is often required. For example, in an application where the decorative surface of a decorative film is fixed to a transparent member, the adhesive sheet has suppressed optical distortion, making the decorative surface easily visible through the adhesive sheet, and it can function as a bonding means that does not impair the design, aesthetics, or high-quality feel of the decorative surface.

[0024] The adhesive sheet with a release film disclosed herein can be provided in the form of a roll of adhesive sheet with a release film around which said adhesive sheet with a release film is wound. Such a roll is easy to handle during storage and transportation and is also advantageous in terms of productivity.

Brief Description of the Drawings

[0025] [Figure 1] It is a schematic cross-sectional view showing an adhesive sheet with a release film according to an embodiment. [Figure 2] It is a schematic cross-sectional view showing an adhesive sheet with a release film according to another embodiment.

Mode for Carrying Out the Invention

[0026] Hereinafter, preferred embodiments of the present invention will be described. In addition, matters other than those specifically mentioned in this specification and necessary for the implementation of the present invention can be understood by those skilled in the art based on the teachings regarding the implementation of the invention described in this specification and the common technical knowledge at the time of filing. The present invention can be implemented based on the content disclosed in this specification and the common technical knowledge in the relevant field. Also, in the following drawings, members and parts having the same function may be denoted by the same reference numerals for description, and redundant descriptions may be omitted or simplified. In addition, the embodiments shown in the drawings are schematized for clearly explaining the present invention and do not necessarily accurately represent the size and scale of the actually provided product.

[0027] As described above, in this specification, the “adhesive” refers to a material that exhibits a soft solid (viscoelastic body) state in the temperature range near room temperature and has the property of easily adhering to an adherend by pressure. The adhesive referred to here is generally, as defined in “C. A. Dahlquist, “Adhesion : Fundamental and Practice”, McLaren & Sons, (1966) P. 143”, a complex tensile elastic modulus E * (1Hz)<10 7 dyne / cm 2It may be a material having properties that satisfy the above conditions (typically, a material having the above properties at 25°C).

[0028] In this specification, "acrylic polymer" refers to a polymer derived from a monomer component containing more than 50% by weight of acrylic monomers, and is also called an acrylic polymer. The above-mentioned acrylic monomer refers to a monomer having at least one (meth)acryloyl group in one molecule. In this specification, "(meth)acryloyl" comprehensively refers to acryloyl and methacryloyl. Similarly, "(meth)acrylate" comprehensively refers to acrylate and methacrylate, and "(meth)acrylic" comprehensively refers to acrylic and methacrylic. In this specification, "mass" and "weight" shall be considered synonymous.

[0029] In this specification, "photoreactive monomer" is a compound having at least one functional group (photoreactive functional group) in its molecule that can undergo a reaction upon irradiation with light, and is typically a compound having at least one ethylenically unsaturated group in its molecule as the above-mentioned photoreactive functional group. The photoreactive monomer referred to herein can be any monomer that can undergo a reaction, and may, for example, be a polymer such as an oligomer or polymer (for example, a polymer having at least one ethylenically unsaturated group in its molecule).

[0030] Furthermore, in this specification, "photocurable" refers to the property of hardening upon irradiation with light such as ultraviolet light. For example, a photocurable adhesive composition refers to a composition that hardens upon photocuring to become an adhesive or adhesive layer. A photocurable adhesive layer refers to an adhesive layer that can be hardened upon irradiation with light such as ultraviolet light, and is used to refer to the adhesive layer before photocuring treatment of an adhesive layer that hardens completely upon photocuring treatment. A photocurable adhesive sheet is used to refer to an adhesive sheet that has such a photocurable adhesive layer.

[0031] <Example of a configuration for an adhesive sheet with a release film> Figure 1 shows an example configuration of an adhesive sheet with a release film disclosed herein. This adhesive sheet with a release film 1 comprises a double-sided adhesive sheet 10, a first release film 21, and a second release film 22. The adhesive sheet 10 has a first adhesive surface 10a and a second adhesive surface 10b on the opposite side of the first adhesive surface 10a. The adhesive sheet 10 in this embodiment is a substrate-less double-sided adhesive sheet consisting of an adhesive layer 12, and therefore the first adhesive surface 10a and the second adhesive surface 10b are the first surface 12a and the second surface 12b of the adhesive layer 12, respectively. The first release film 21 is placed on the first adhesive surface 10a of the adhesive sheet 10, and one of its surfaces (first adhesive surface side surface S1) 21a is in peelable contact with the first adhesive surface 10a of the adhesive sheet 10. The second release film 22 is placed on the second adhesive surface 10b of the adhesive sheet 10, and one of its surfaces (second adhesive surface side surface S2) 22a is in peelable contact with the second adhesive surface 10b of the adhesive sheet 10. The first adhesive surface side surface (S1) 21a of the first release film 21 and the second adhesive surface side surface (S2) 22a of the second release film 22 are release surfaces having a release treatment layer, for example, a silicone-based release treatment agent. Thus, the adhesive sheet 1 with release films is configured such that the first adhesive surface 10a and the second adhesive surface 10b of the adhesive sheet 10 are protected by the first release film 21 and the second release film 22, respectively. When the adhesive sheet 10 is used, the first release film 21 and the second release film 22 are removed, exposing the first adhesive surface 10a and the second adhesive surface 10b, which are then attached to the adherend.

[0032] Furthermore, the adhesive sheet 1 with release film may be in the form of a roll (adhesive sheet roll with release film) 100 as shown in Figure 1. Such an adhesive sheet roll 100 has the adhesive sheet 1 with release film wound around a core (winding core) 50.

[0033] Figure 2 schematically shows the structure of an adhesive sheet with a release film according to another embodiment. The adhesive sheet with a release film 2 shown in Figure 2 comprises a single-sided adhesive sheet (single-sided adhesive sheet) 10 and a release film 21. The single-sided adhesive sheet 10 comprises an adhesive layer 12 and a support base material 14 that supports the adhesive layer 12, with one side (the first surface 12a of the adhesive layer 12) being the adhesive surface 10a and the other side being the back surface (non-adhesive surface). In this embodiment, the back surface of the adhesive sheet 10 is formed by one side 14b of the support base material 14 (the side opposite to the adhesive layer side surface 14a of the support base material 14). The second surface 12b of the adhesive layer 12 is fixed to the other side 14a of the support base material 14 (the adhesive layer side surface), and this adhesive layer side surface 14a can be said to be a non-peelable surface (non-peelable surface). Thus, the adhesive layer 12 is provided without the intention of separating it from the support base material 14. On the other hand, the surface (adhesive surface side surface S1) 21a of the release film 21 is a release surface, similar to the case of the first release film in Figure 1, and is in peelable contact with the adhesive surface 10a of the adhesive layer 12, protecting the adhesive surface 10a. This adhesive sheet 2 with release film can also be provided in the form of a roll (adhesive sheet roll) 200 as shown in Figure 2. The adhesive sheet roll 200 has an adhesive sheet 10 comprising an adhesive layer 12 and a support substrate 14, and an adhesive sheet 2 with release film 21 wound around a core (winding core).

[0034] Although Figure 1 illustrates a roll body 100 in which an adhesive sheet 1 with a release film is wound around a core 50, the roll body 100 may also be in a form without a core 50, that is, a so-called coreless type roll body in which the adhesive sheet 1 with a release film is wound alone. The same applies to the roll body 200 shown in Figure 2.

[0035] Furthermore, the adhesive sheet 1 (before use) shown in Figure 1 had a configuration in which the first adhesive surface 10a and the second adhesive surface 10b were protected by a first release film 21 and a second release film 22, respectively, with at least the adhesive surface side being a release surface. However, the second release film 22 may be omitted, and a release film 21 with release surfaces on both sides may be used. By winding the adhesive sheet 1 so that the second adhesive surface 10b comes into contact with the back surface of the release film 21, the second adhesive surface 10b may also be protected by the release film 21.

[0036] Furthermore, the adhesive sheet may be a substrate-less adhesive sheet as shown in Figure 1, a single-sided adhesive sheet with a substrate as shown in Figure 2, or even a double-sided adhesive sheet with a substrate. Specifically, the adhesive sheet may be an adhesive sheet with a non-peelable substrate embedded (embedded) within it. As the substrate, plastic film, paper, nonwoven fabric, etc., can be used. In addition, although Figures 1 and 2 illustrate a configuration in which the adhesive layer 10 has a single-layer structure, the composition of the adhesive layer 10 is not limited to this. For example, the adhesive layer may be composed of two or more sub-adhesive layers made of the same or different adhesives.

[0037] <Release film> (Maximum height Rz on the adhesive side surface) The release film disclosed herein has a maximum height Rz of 400 nm or less on the adhesive side surface. This allows the adhesive surface of the adhesive sheet to have high surface smoothness. Furthermore, in a configuration in which the first and second release films are arranged on each adhesive surface of the adhesive sheet, the maximum height Rz1 of the first adhesive side surface S1 of the first release film and the maximum height Rz2 of the second adhesive side surface S2 of the second release film are both 400 nm or less. As a result, each adhesive surface of the double-sided adhesive sheet has high surface smoothness, and both adhesive surfaces can exhibit high surface smoothness when attached to an adherend.

[0038] The maximum height Rz of the adhesive side surface of the release film (including the maximum height Rz1 of the first adhesive side surface S1 of the first release film and the maximum height Rz2 of the second adhesive side surface S2 of the second release film; the same applies hereinafter unless otherwise specified) is preferably about 340 nm or less, more preferably about 280 nm or less, and even more preferably about 240 nm or less, and may be less than 200 nm, less than 150 nm, or less than 120 nm. Furthermore, from the viewpoint of ease of manufacturing and handling of the release film, in some embodiments, the above maximum height Rz may be, for example, about 50 nm or more, about 80 nm or more, or about 100 nm or more. In embodiments comprising first and second release films, the maximum height Rz1 of the first adhesive side surface S1 of the first release film and the maximum height Rz2 of the second adhesive side surface S2 of the second release film may be the same or different.

[0039] (Arithmetic mean roughness Ra of the adhesive side surface) Furthermore, it is preferable from the viewpoint of achieving an adhesive surface with high surface smoothness that the arithmetic mean roughness Ra of the adhesive side surface of the release film is limited to a predetermined value or less (for example, approximately 100 nm or less, and even less than 50 nm). Also, in a configuration in which the first and second release films are arranged on each adhesive surface of the adhesive sheet, it is appropriate that the arithmetic mean roughness Ra1 of the surface S1 of the first release film and the arithmetic mean roughness Ra2 of the second adhesive side surface S2 of the second release film are limited to approximately 100 nm or less (and even less than 50 nm). In some embodiments, the arithmetic mean roughness Ra of the adhesive side surface of the release film (including the arithmetic mean roughness Ra1 of the first adhesive side surface S1 of the first release film and the arithmetic mean roughness Ra2 of the second adhesive side surface S2 of the second release film; the same applies hereinafter unless otherwise specified) is preferably approximately 30 nm or less, may be approximately 25 nm or less, may be approximately 20 nm or less, and may be approximately 18 nm or less. Furthermore, from the viewpoint of ease of manufacturing and handling of the release film, in some embodiments, the arithmetic mean roughness Ra may be, for example, approximately 5 nm or more, approximately 10 nm or more, or approximately 15 nm or more. In embodiments comprising first and second release films, the arithmetic mean roughness Ra1 of the first adhesive side surface S1 of the first release film and the arithmetic mean roughness Ra2 of the second adhesive side surface S2 of the second release film may be the same or different.

[0040] (Surface properties of the back) The maximum height Rz and arithmetic mean roughness Ra of the back surface (opposite the adhesive layer side) of the release film (including the first and second release films) are not particularly limited. The maximum height Rz of the back surface (opposite the adhesive layer side) of the release film may be greater than 400 nm (e.g., approximately 500 nm or more) or greater than 800 nm (e.g., 1000 nm or more) from the viewpoint of productivity, etc. The arithmetic mean roughness Ra of the back surface (opposite the adhesive layer side) of the release film may be greater than 30 nm (e.g., greater than 35 nm, and even greater than approximately 50 nm) from the viewpoint of productivity, etc.

[0041] The maximum height Rz and arithmetic mean roughness Ra of the release film surface can be adjusted by selecting the film material, molding method, surface treatment such as release treatment, etc. For example, this can be done by adjusting the smoothness of the layers constituting the release surface (antiblocking layer, hard coat layer, oligomer prevention layer, etc.), reducing or eliminating (particle-free) filler particles in the surface layer or release film substrate, and adjusting the stretching conditions.

[0042] The maximum height Rz and arithmetic mean roughness Ra of the release film surface are measured using a non-contact surface roughness measuring device. As the non-contact surface roughness measuring device, an optical interference type surface roughness measuring device is used, for example, a 3D optical profiler (product name "NewView7300", manufactured by ZYGO) or an equivalent can be used. For example, a glass plate (soda-lime glass plate manufactured by MATSUNAMI, 1.3 μm thick) can be attached to the surface of the release film opposite to the measurement surface using adhesive, and the surface shape can be measured using a 3D optical profiler (product name "NewView7300", manufactured by ZYGO) in an environment of 23°C and 50% RH. The same applies to the examples described later. The specific measurement conditions and calculation methods are the same as those for measuring the maximum height Rz and arithmetic mean roughness Ra of the adhesive surface of the adhesive sheet described in the examples described later.

[0043] The release film (including the first and second release films; the same applies hereinafter unless otherwise specified) may be selected and used if the maximum height Rz of the adhesive surface is 400 nm or less. Non-limiting examples of release films that can be used include release films having a release treatment layer on the surface of the release film substrate; and release films made of low-adhesion resins such as fluoropolymers (polytetrafluoroethylene, etc.) or polyolefin resins (polyethylene, polypropylene, etc.).

[0044] The release film disclosed herein preferably has a release treatment layer on a release film substrate. The release treatment layer may be formed by surface-treating the release film substrate with a release treatment agent. The release treatment agent may be a known release treatment agent such as a silicone-based release treatment agent, a long-chain alkyl-based release treatment agent, a fluorine-based release treatment agent, or molybdenum(IV) sulfide. In some embodiments, a release film having a release treatment layer made of a silicone-based release treatment agent may be preferably used. The thickness and formation method of the release treatment layer are not particularly limited and can be set so that appropriate release properties are exhibited on the adhesive side surface of the release film.

[0045] Various plastic films can be used as the release film substrate. In this specification, "plastic film" is typically a non-porous sheet and is a concept distinct from, for example, nonwoven fabrics (i.e., does not include nonwoven fabrics).

[0046] Examples of materials for the above-mentioned plastic film include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN); polyolefin resins such as polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, and ethylene-butene copolymer; cellulose resins such as triacetylcellulose; acetate resins; polysulfone resins; polyethersulfone resins; polycarbonate resins; polyamide resins; polyimide resins; norbornene resins; cyclic polyolefin resins; (meth)acrylic resins; polyvinyl chloride resins; polyvinylidene chloride resins; polystyrene resins; polyvinyl alcohol resins; ethylene-vinyl acetate copolymer resins; ethylene-vinyl alcohol copolymer resins; polyarylate resins; and polyphenylene sulfide resins. A release film substrate formed from one or more of these resins can be used. Among these, a polyester resin film (e.g., PET film) formed from a polyester resin is a preferred release film substrate.

[0047] The plastic film used as the release film substrate described above may be an unoriented film, a uniaxially oriented film, or a biaxially oriented film. Furthermore, the plastic film may have a single-layer structure or a multilayer structure including two or more sublayers. The plastic film may contain known additives that can be used in release film substrates for adhesive sheets, such as antioxidants, anti-aging agents, heat stabilizers, light stabilizers, UV absorbers, colorants such as pigments and dyes, lubricants, fillers, antistatic agents, and nucleating agents. In a multilayer plastic film, each additive may be incorporated into all sublayers or into only some of the sublayers.

[0048] In some preferred embodiments, the release film substrate (typically a plastic film) may preferably have a limited content of particles such as inorganic particles (which may be pigments, lubricants, fillers, etc.) in the layer on the release side, or may be substantially free of such particles. Here, substantially free means that the amount of particles (e.g., inorganic particles) in the layer is less than 1% by weight, preferably less than 0.1% by weight (e.g., 0 to 0.01% by weight). Release films equipped with such a release film substrate tend to have a low maximum height Rz and arithmetic mean roughness Ra of the release surface. When the release film substrate (typically a plastic film) has a multilayer structure, the particle content in the layer on the release side may be 1 / 10 or less (e.g., 1 / 50 or less) of the particle content in the layers other than the release side layer.

[0049] In embodiments comprising first and second release films, the first release film and the second release film may have the same material and structure, or they may have different materials and structures.

[0050] The thickness of the release film is not particularly limited and may be, for example, around 10 μm to 500 μm. From the viewpoint of the strength and dimensional stability of the release film, it is appropriate for the thickness of the release film to be 20 μm or more, preferably 30 μm or more, and may also be 35 μm or more, 40 μm or more, or 45 μm or more. In some preferred embodiments, the thickness of the release film is approximately 50 μm or more, may also be approximately 60 μm or more, or approximately 70 μm or more. This ensures that the release film has sufficient thickness and prevents the smoothness of the adhesive sheet surface from being impaired (dents) through the release film. Furthermore, from the viewpoint of the handling of the release film (e.g., ease of winding), it is appropriate for the thickness of the release film to be 300 μm or less, preferably 250 μm or less, and may also be 200 μm or less, 150 μm or less, or 130 μm or less. In some preferred embodiments, the thickness of the release film is approximately 125 μm or less, may be approximately 115 μm or less, approximately 105 μm or less, or approximately 90 μm or less. By setting the thickness of the release film to a predetermined value or less, winding marks are less likely to occur when the film is rolled, removal from the adhesive sheet becomes smoother, and the adhesive surface of the adhesive sheet is more likely to maintain high surface smoothness even after the release film is removed.

[0051] In embodiments comprising first and second release films, the thicknesses of the first and second release films may be the same or different. From the viewpoint of ease of peeling, it is preferable that the first and second release films have different thicknesses, and that the thickness of the thicker release film is approximately 1.1 times or more, for example, approximately 1.25 times or more, than the thickness of the thinner release film.

[0052] Furthermore, a carrier or auxiliary film may be attached to the back of the release film as needed. The presence of such a backing auxiliary film makes it easier to prevent dents, even when using a thin release film, and can improve workability in processes such as die-cutting. As such a backing auxiliary film, a known or conventional adhesive tape with a resin film base can be used.

[0053] <Release strength of release film> In the adhesive sheet with release film disclosed herein, it is preferable that the peeling force of the release film from the adhesive sheet is limited to a predetermined value or less. This suppresses the fine waviness of the adhesive surface caused by the so-called stick-slip phenomenon resulting from peeling from the release film when removing the release film from the adhesive surface during use of the adhesive sheet, making it easier to obtain a smoother adhesive surface. In some preferred embodiments, the peeling force of the release film is approximately 1 N / 50 mm or less, more preferably less than 0.90 N / 50 mm, even more preferably less than 0.70 N / 50 mm, particularly preferably less than 0.50 N / 50 mm, and may also be less than 0.40 N / 50 mm, less than 0.30 N / 50 mm, less than 0.20 N / 50 mm, or less than 0.10 N / 50 mm. The lower limit of the peeling force of the release film is, for example, 0.01 N / 50 mm or more, and may be 0.05 N / 50 mm or more from the viewpoint of protection by the release film and prevention of lifting. The peeling force of the release film can be adjusted by applying a peeling treatment to the surface of the release film.

[0054] In embodiments comprising first and second release films, it is preferable that the peeling force of the first release film and the peeling force of the second release film on the adhesive sheet differ from the viewpoint of peeling workability. For example, the peeling force of the heavily peeling side release film (e.g., the second release film) is appropriately set to be approximately 1.2 times or more the peeling force of the lightly peeling side release film (e.g., the first release film), preferably approximately 1.4 times or more, and may also be approximately 1.5 times or more, or approximately 1.8 times or more. From the viewpoint of maintaining light peelability, it is appropriate that the peeling force of the heavily peeling side release film (e.g., the second release film) is approximately 3 times or less the peeling force of the lightly peeling side release film (e.g., the first release film), and may also be approximately 2 times or less.

[0055] The peeling force of the release film is measured using an adhesive sheet with a release film attached, cut to a length of 150 mm and a width of 50 mm, under conditions of 23°C, 50% RH, a tensile speed of 300 mm / min, and a peeling angle of 180°. Specifically, it is measured using the method described in the examples below.

[0056] <Adhesive sheet> (Surface properties of the adhesive surface) The adhesive sheet disclosed herein has an adhesive surface in which the maximum height Rz is limited to a predetermined value or less. A configuration with an adhesive surface designed to have a low maximum height Rz allows for high surface smoothness, resulting in no optical distortion or suppressed optical distortion. Such an adhesive sheet can, for example, not impair the design of the adherend, or its aesthetic appeal or premium feel, when the adherend surface is viewed through the adhesive sheet. If the adhesive sheet is in the form of a double-sided adhesive sheet having adhesive surfaces on both sides, it is appropriate that the maximum height Rz of the first and second adhesive surfaces constituting the double-sided adhesive sheet is limited to a predetermined value or less. By having high surface smoothness on each adhesive surface of the double-sided adhesive sheet, adhesion with no optical distortion or highly suppressed optical distortion can be achieved. For example, if one adherend is a transparent member and the other is an adherend with a design, the design of the adherend can be clearly viewed through the adhesive sheet.

[0057] The maximum height Rz of the adhesive surface of the adhesive sheet (including the first and second adhesive surfaces; the same applies hereinafter unless otherwise specified) is preferably about 600 nm or less, more preferably about 500 nm or less, even more preferably about 450 nm or less, and particularly preferably about 400 nm or less, and may be less than 350 nm, less than 300 nm, or less than 250 nm. From the viewpoint of production efficiency, etc., in some embodiments, the maximum height Rz of the adhesive surface of the adhesive sheet may be, for example, about 10 nm or more, about 50 nm or more, about 100 nm or more, or about 200 nm or more. In embodiments in which the adhesive sheet has a first adhesive surface and a second adhesive surface, the maximum height Rz of the first adhesive surface and the maximum height Rz of the second adhesive surface may be about the same or different.

[0058] Preferably, the adhesive surface of the adhesive sheet disclosed herein has an arithmetic mean roughness Ra limited to a predetermined value or less. A configuration with an adhesive surface designed to have a low arithmetic mean roughness Ra makes it easier to suppress optical distortion to a high degree. When the adhesive sheet is in the form of a double-sided adhesive sheet having adhesive surfaces on both sides, it is appropriate that the arithmetic mean roughness Ra of the first adhesive surface and the second adhesive surface constituting the double-sided adhesive sheet is limited to a predetermined value or less. By having high surface smoothness on each adhesive surface of the double-sided adhesive sheet, it is possible to preferably achieve adhesion with no optical distortion or with highly suppressed optical distortion.

[0059] The arithmetic mean roughness Ra of the adhesive surface of the adhesive sheet is preferably about 70 nm or less, more preferably about 65 nm or less, and even more preferably about 55 nm or less, and may be less than 50 nm, less than 45 nm, or less than 40 nm. From the viewpoint of production efficiency, etc., in some embodiments, the arithmetic mean roughness Ra of the adhesive surface of the adhesive sheet may be, for example, about 10 nm or more, about 20 nm or more, or about 30 nm or more (for example, about 40 nm or more). In embodiments in which the adhesive sheet has a first adhesive surface and a second adhesive surface, the arithmetic mean roughness Ra of the first adhesive surface and the arithmetic mean roughness Ra of the second adhesive surface may be of the same magnitude or may be different.

[0060] The maximum height Rz and arithmetic mean roughness Ra of the adhesive surface of the adhesive sheet can be adjusted by the surface properties of the release film laminated on the adhesive surface, the peeling force of the release film from the adhesive sheet, the thickness of the adhesive layer, and so on.

[0061] Furthermore, the maximum height Rz of the adhesive surface of the adhesive sheet described above may be the maximum height Rz of the surface of the adhesive layer constituting the adhesive sheet. Similarly, the arithmetic mean roughness Ra of the adhesive surface of the adhesive sheet described above may be the arithmetic mean roughness Ra of the surface of the adhesive layer constituting the adhesive sheet. Therefore, the ranges and values ​​described above as the maximum height Rz and arithmetic mean roughness Ra of the adhesive surface of the adhesive sheet can be adopted, respectively.

[0062] Furthermore, the maximum height Rz and arithmetic mean roughness Ra of the adhesive surface of the adhesive sheet are measured on the adhesive surface of the adhesive sheet after the release film has been peeled off from the adhesive sheet with the release film attached, using a non-contact surface roughness measuring device. As the non-contact surface roughness measuring device, an optical interference type surface roughness measuring device is used, for example, a 3D optical profiler (product name "NewView7300", manufactured by ZYGO Corporation) or an equivalent product can be used. The specific measurement operation and measurement conditions can be set according to the measurement conditions described in the examples below, or to obtain results equivalent to or corresponding to those obtained by following those measurement conditions.

[0063] (Total light transmittance) In some embodiments, the total light transmittance of the adhesive sheet is appropriately approximately 50% or more, and preferably approximately 70% or more. From the viewpoint of visibility of the adherend through the adhesive sheet, in some preferred embodiments, the total light transmittance of the adhesive sheet is approximately 85% or more, and more preferably approximately 90% or more. Theoretically, the upper limit of the total light transmittance is the value obtained by subtracting the light loss due to reflection at the air interface (Fresnel loss) from 100%, and in practical terms, it may be approximately 95% or less, and may be approximately 94% or less (for example, 93% or less). With an adhesive sheet having such a total light transmittance, good visibility can be obtained through the adhesive sheet.

[0064] (Haze value) In some embodiments, the haze value of the adhesive sheet is, for example, approximately 10% or less, and preferably approximately 3% or less. From the viewpoint of visibility of the object to be adhered through the adhesive sheet, in some preferred embodiments, the haze value of the adhesive sheet is approximately 1% or less, more preferably approximately 0.8% or less, and even more preferably 0.5% or less. The lower limit of the above haze value is theoretically 0%, and in practice, it may be approximately greater than 0.0%. Note that "haze value" refers to the ratio of diffusely transmitted light to total transmitted light when visible light is irradiated onto the object to be measured. It is also called the cloudiness value. The haze value can be expressed by the following formula. Th[%] = Td / Tt × 100 In the above formula, Th is the haze value [%], Td is the scattered light transmittance, and Tt is the total light transmittance.

[0065] Furthermore, the total light transmittance and haze value of the adhesive sheet can be adjusted by the composition (base polymer type and additives), thickness, etc., of the adhesive sheet (typically the adhesive layer).

[0066] Furthermore, the total light transmittance of the adhesive sheet may be the total light transmittance of the adhesive layer constituting the adhesive sheet. Similarly, the haze value of the adhesive sheet may be the haze value of the adhesive layer constituting the adhesive sheet. Therefore, the ranges and values ​​described above for the total light transmittance and haze value of the adhesive sheet can be adopted as the ranges and values ​​for the total light transmittance and haze value of the adhesive layer, respectively.

[0067] Furthermore, the total light transmittance and haze value of the adhesive sheet can be measured by attaching the adhesive sheet to one side of a glass plate and using a haze meter. A haze meter such as the "HM-150N" manufactured by Murakami Color Technology Laboratory or an equivalent product can be used. Specifically, the measurements are performed using the method described in the examples below.

[0068] Adhesive sheets having the total light transmittance and haze value described above may be colored transparent or colorless transparent adhesive sheets. In this specification, "transparent" is used to include the concept of translucency. Furthermore, the optical distortion reduction effect of the adhesive sheet by the technology disclosed herein can be achieved in a configuration in which at least a part of the adhesive sheet surface has enough transparency to allow visibility through the adhesive sheet; therefore, the adhesive sheet does not need to be transparent or translucent.

[0069] (Adhesion to glass) The adhesive strength of the adhesive sheet disclosed herein is not particularly limited and can be set according to the purpose. In some embodiments, the adhesive strength of the adhesive sheet to the glass plate (adhesion to glass) is suitable to be, for example, approximately 1.0 N / 20 mm or more, and may be approximately 3.0 N / 20 mm or more (for example, approximately 5.0 N / 20 mm or more). From the viewpoint of bonding reliability, the above adhesion to glass is preferably approximately 7.0 N / 20 mm or more, more preferably approximately 8.0 N / 20 mm or more, even more preferably approximately 9.0 N / 20 mm or more, and may also be approximately 10.0 N / 20 mm or more, or approximately 11.0 N / 20 mm or more. An adhesive sheet having the above adhesion to glass can be preferably used for purposes such as joining and fixing members. Furthermore, from the viewpoint of easily balancing with other characteristics, the above-mentioned adhesive strength to glass may be, for example, approximately 20 N / 20 mm or less, approximately 16.0 N / 20 mm or less, or approximately 12.0 N / 20 mm or less. The above-mentioned adhesive strength to glass can be adjusted by selecting the composition and thickness of the adhesive layer, etc.

[0070] The adhesion strength to glass is determined by pressing the adhesive surface to be measured against a glass plate by moving a 2 kg rubber roller back and forth once, and then measuring the peel strength when peeling the adhesive sheet from the glass plate using a tensile testing machine in an environment of 23°C and 50% RH, in accordance with JIS Z 0237, under conditions of a peel angle of 180 degrees and a tensile speed of 300 mm / min. Specifically, it is measured by the method described in the examples below.

[0071] (Module of elasticity determined by tensile testing) In some preferred embodiments, the adhesive sheet has an elastic modulus (also called initial elastic modulus) of 3.0 MPa or higher as determined by a tensile test. Adhesive sheets with a higher elastic modulus tend to exhibit better deformation resistance. Such adhesive sheets with a high elastic modulus can be preferably used for purposes such as joining or fixing members. For example, in an embodiment where two members are joined via an adhesive sheet, the high deformation resistance of the adhesive sheet can help maintain the relative positions of the two members with high accuracy. Also, in an embodiment where a film member and another member are joined via an adhesive sheet, the high deformation resistance of the adhesive sheet can help suppress the phenomenon of changes in the appearance of the laminate due to localized pressure from the film member side (pressure deformation resistance). In an embodiment where the adherend is a transparent rigid member (e.g., a glass member), suppressing changes in appearance visible from the adherend side is particularly significant.

[0072] In some preferred embodiments of the adhesive sheet, the modulus of elasticity may be, for example, 5.0 MPa or higher, 7.0 MPa or higher, 10.0 MPa or higher, 15.0 MPa or higher, or 20.0 MPa or higher. Deformation resistance tends to improve with increasing modulus of elasticity. There is no particular upper limit to the modulus of elasticity. From the viewpoint of easily balancing with other properties (e.g., one or more properties selected from impact resistance, glass adhesion, haze value, etc.), it is advantageous for the modulus of elasticity to be 150 MPa or lower, preferably 120 MPa or lower, and may also be 100 MPa or lower, 80 MPa or lower, or 60 MPa or lower. The modulus of elasticity determined by the tensile test can be adjusted by selecting the composition of the adhesive sheet (typically the adhesive layer). The modulus of elasticity determined by the tensile test is measured by the tensile test described above. More specifically, it is measured by the method described in the examples described later.

[0073] (Impact resistance) The adhesive sheet disclosed herein has an impact resistance of 2.0 J / 10 mm 2The above is preferable. With the above impact-resistant adhesive sheet, a highly reliable bond can be formed. This can be an advantageous feature for adhesive sheets used, for example, for joining or fixing members. Such an adhesive sheet can withstand impacts such as drops or collisions and maintain a good bond between the member and the adherend.

[0074] In some preferred embodiments of adhesive sheets, the impact resistance is, for example, 2.1 J / 10 mm 2 The above is sufficient, 2.3J / 10mm 2 The above is also acceptable, 2.5J / 10mm 2 The above is also acceptable, 2.7J / 10mm 2 The above is also acceptable, 3.0J / 10mm 2 The above is also acceptable. The adhesive sheet disclosed herein has an impact resistance of 3.3J / 10mm 2 or larger or 3.5J / 10mm 2 The above-mentioned embodiments may also be preferably implemented. The upper limit of the above impact resistance is not particularly limited. From the viewpoint of easily balancing with other characteristics, the above impact resistance may be, for example, 20J / 10mm 2 The following are acceptable: 15J / 10mm 2 The following is also acceptable: 10J / 10mm 2 The following is also acceptable: 8.0J / 10mm 2 The following is also acceptable: 6.0J / 10mm 2 The following is also acceptable. Impact resistance can be adjusted by selecting the composition and thickness of the adhesive layer. Impact resistance is measured by the shear impact test described above. More specifically, it is measured by the method described in the examples below.

[0075] (thickness) The thickness of the adhesive sheet is appropriately set according to the purpose and manner of use and is not limited to a specific range. The thickness of the adhesive sheet may be, for example, about 1 μm to 500 μm, and may be, for example, about 3 μm to 500 μm. In some embodiments, the thickness of the adhesive sheet is suitable to be 5 μm or more, for example, it may be 10 μm or more, preferably 20 μm or more, more preferably 25 μm or more, and may exceed 25 μm. With thicker adhesive sheets, optical distortion is easily reduced due to the stress distribution ability of the adhesive layer. In addition, thicker adhesive sheets tend to have excellent step-following ability and easily absorb deformation caused by foreign matter, etc. Impact resistance also tends to be improved. The technology disclosed herein can preferably be implemented in embodiments in which the thickness of the adhesive sheet is 30 μm or more. The thickness of the above adhesive sheet may be 35 μm or more, 40 μm or more, 45 μm or more, 50 μm or more, 75 μm or more, or 90 μm or more. On the other hand, as the thickness of the adhesive sheet increases, the optical path passing through the adhesive sheet also becomes longer, making optical distortion more easily noticeable. For this reason, in some embodiments, the thickness of the adhesive sheet is appropriately set to, for example, 200 μm or less, but may also be 150 μm or less, 120 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, or 35 μm or less.

[0076] <Adhesive layer> In the technology disclosed herein, the type of adhesive constituting the adhesive layer contained in the adhesive sheet is not particularly limited. The adhesive layer may be composed of one or more adhesives selected from various known adhesives such as acrylic adhesives, rubber adhesives (natural rubber, synthetic rubber, mixtures thereof, etc.), silicone adhesives, polyester adhesives, urethane adhesives, polyether adhesives, polyamide adhesives, and fluorine-based adhesives. Here, acrylic adhesive refers to an adhesive whose base polymer is an acrylic polymer (the main component among the polymer components, i.e., a component contained in more than 50% by weight). The same meaning applies to rubber adhesives and other adhesives.

[0077] (Polymer (A)) In some embodiments, the adhesive layer contains polymer (A). Examples of materials that can be used as polymer (A) include polymers that exhibit rubber elasticity at room temperature, such as acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, and fluoropolymers, which are known in the field of adhesives. These can be used individually or in combination of two or more.

[0078] The weight percentage of polymer (A) in the total weight of the adhesive layer is appropriately 40% by weight or more, preferably 50% by weight or more, more preferably 60% by weight or more, and even more preferably 70% by weight or more, and may be approximately 80% by weight or more, approximately 90% by weight or more, and may be approximately 97% by weight or more (for example, approximately 99% by weight or more). Adhesives with a high polymer (A) content tend to have excellent transparency. In addition, the weight percentage of polymer (A) in the total weight of the adhesive layer is typically less than 100% by weight, and from the viewpoint of easily adjusting the balance of properties, it is advantageous to be 95% by weight or less, preferably 92% by weight or less, and may be 90% by weight or less, and may be 87% by weight or less.

[0079] One preferred example of polymer (A) is an acrylic polymer. The adhesive layer in the technology disclosed herein may be an acrylic adhesive layer containing an acrylic polymer as the base polymer (the main component of the polymer components, i.e., the component accounting for more than 50% by weight). Acrylic adhesives are preferred from the viewpoint of transparency and weather resistance, and they easily achieve viscoelastic properties with excellent impact resistance without relying heavily on additives such as softeners. The acrylic polymer as polymer (A) (hereinafter sometimes referred to as "acrylic polymer (A)") is preferably an acrylic polymer composed of monomer components containing 40% by weight or more of alkyl (meth)acrylate ester having a linear or branched alkyl group with 1 to 20 carbon atoms at the ester end. Hereinafter, alkyl (meth)acrylate ester having an alkyl group with X to Y carbon atoms at the ester end will be referred to as "(meth)acrylate C X-Y It is sometimes written as "alkyl ester".

[0080] In some embodiments, (meth)acrylic acid C is included in the entire monomer component of the acrylic polymer (A). 1-20 The proportion of alkyl esters is appropriately greater than 40% by weight, as it allows for a good balance of properties. For example, it may be 45% by weight or more, 50% by weight or more, 55% by weight or more, or 60% by weight or more. Among the monomer components, (meth)acrylic acid C 1-20 The proportion of alkyl ester can be 100% by weight, but it is appropriate to have 98% by weight or less to easily balance the properties, for example it may be 95% by weight or less, or even 90% by weight or less. In some embodiments, C is included in the total monomer component of the acrylic polymer (A). 1-20 The proportion of alkyl methacrylate may be, for example, 85% by weight or less, 80% by weight or less, 75% by weight or less, 70% by weight or less, 65% by weight or less, or 60% by weight or less, from the viewpoint of improving the cohesiveness of the adhesive layer.

[0081] (meth)acrylic acid C 1-20Non-specific examples of alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and i Examples include sooctyl, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate.

[0082] Of these, at least (meth)acrylic acid C 4-20 It is preferable to use an alkyl ester, and at least (meth)acrylic acid C 4-18 It is more preferable to use alkyl esters. Particularly preferred is (meth)acrylic acid C 4-18 Examples of alkyl esters include n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA). (meth)acrylate C is a preferred choice. 4-20 Other specific examples of alkyl esters include isononyl acrylate, n-butyl methacrylate (BMA), 2-ethylhexyl methacrylate (2EHMA), and isostearyl acrylate (iSTA). These (meth)acrylate C 4-20 Alkyl esters can be used individually or in combination of two or more types.

[0083] The monomer component preferably includes, for example, either n-butyl acrylate (BA) or 2-ethylhexyl acrylate (2EHA), or both. In some embodiments, the monomer component preferably includes at least BA. Here, examples of monomer components containing at least BA include monomer components with a composition that contains BA but does not contain 2EHA, and monomer components with a composition that contains both BA and 2EHA, but in which the 2EHA content is less than the BA content (for example, the 2EHA content is less than 0.5 or 0.3 times the BA content).

[0084] In some embodiments, the monomer component constituting the acrylic polymer (A) is (meth)acrylic acid C 4-18 It may contain alkyl esters in a proportion of 40% by weight or more. (meth)acrylate C in the monomer component. 4-18 The proportion of alkyl ester may be, for example, 50% by weight or more, 60% by weight or more, or 65% by weight or more. Furthermore, from the viewpoint of improving the cohesiveness of the adhesive layer, (meth)acrylic acid C is included in the monomer component. 4-18 The proportion of alkyl esters should be 99.5% by weight or less, but may also be 95% by weight or less, 85% by weight or less, or 75% by weight or less.

[0085] The monomer components constituting the acrylic polymer (A) may, optionally, include other monomers copolymerizable with the (meth)acrylate alkyl ester (copolymerizable monomers). Suitable copolymerizable monomers include monomers having polar groups (e.g., carboxyl groups, hydroxyl groups, nitrogen-containing rings, etc.) and monomers with relatively high glass transition temperatures (e.g., 10°C or higher) of the homopolymer. Monomers having polar groups can be useful for introducing crosslinking points into the acrylic polymer (A) or for increasing the cohesive strength of the adhesive. Copolymerizable monomers can be used individually or in combination of two or more.

[0086] Non-specific examples of copolymerizable monomers include the following: Carboxy group-containing monomers: For example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc. Monomers containing acid anhydride groups: For example, maleic anhydride, itaconic anhydride. Hydroxypropyl monomers: For example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, hydroxyalkyl (meth)acrylate such as (4-hydroxymethylcyclohexyl)methyl (meth)acrylate, etc. Monomers containing sulfonic acid groups or phosphate groups: for example, styrene sulfonic acid, allyl sulfonic acid, sodium vinyl sulfonate, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid, 2-hydroxyethylacryloyl phosphate, etc. Epoxy group-containing monomers: For example, epoxy group-containing acrylates such as glycidyl (meth)acrylate and 2-ethyl glycidyl ether (meth)acrylate, allyl glycidyl ether, glycidyl (meth)acrylate, etc. Cyano group-containing monomers: for example, acrylonitrile, methacrylonitrile, etc. Monomers containing isocyanate groups: for example, 2-isocyanate ethyl (meth)acrylate, etc. Amide group-containing monomers: for example, (meth)acrylamide; N,N-dialkyl(meth)acrylamides such as N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, N,N-di(t-butyl)(meth)acrylamide; N-alkyl(meth)acrylamides such as N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, Nn-butyl(meth)acrylamide; N-vinyl carboxylic acid amides such as N-vinylacetamide; monomers having a hydroxyl group and an amide group, for example, N-(2-hydroxyethyl)(meth)acrylamide N-hydroxyalkyl(meth)acrylamides such as N-(2-hydroxypropyl)(meth)acrylamide, N-(1-hydroxypropyl)(meth)acrylamide, N-(3-hydroxypropyl)(meth)acrylamide, N-(2-hydroxybutyl)(meth)acrylamide, N-(3-hydroxybutyl)(meth)acrylamide, and N-(4-hydroxybutyl)(meth)acrylamide; monomers having an alkoxy group and an amide group, for example, N-alkoxyalkyl(meth)acrylamides such as N-methoxymethyl(meth)acrylamide, N-methoxyethyl(meth)acrylamide, and N-butoxymethyl(meth)acrylamide; and others such as N,N-dimethylaminopropyl(meth)acrylamide and N-(meth)acryloylmorpholine. Amino group-containing monomers: for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate. Monomers containing epoxy groups: for example, glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, allyl glycidyl ether. Monomers having a nitrogen atom-containing ring: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-vinylmorpholine, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholindione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, N-vinylisothiazole, N-vinylpyridazine, etc. (for example, lactams such as N-vinyl-2-caprolactam). Monomers having a succinimide skeleton: for example, N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, N-(meth)acryloyl-8-oxyhexamethylenesuccinimide, etc. Maleimides: For example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, etc. Itaconimides: For example, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide, etc. (meth)acrylate aminoalkyls: for example, (meth)acrylate aminoethyl, (meth)acrylate N,N-dimethylaminoethyl, (meth)acrylate N,N-diethylaminoethyl, (meth)acrylate t-butylaminoethyl. Alkoxy group-containing monomers: For example, alkoxyalkyl (alkoxyalkyl (meth)acrylate) types such as 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, and ethoxypropyl (meth)acrylate; alkoxyalkylene glycol (e.g., alkoxypolyalkylene glycol (meth)acrylate) types such as methoxyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate. Alkoxysilyl group-containing monomers: For example, alkoxysilyl group-containing (meth)acrylates such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane, as well as alkoxysilyl group-containing vinyl compounds such as vinyltrimethoxysilane and vinyltriethoxysilane. Vinyl esters: For example, vinyl acetate, vinyl propionate, etc. Vinyl ethers: For example, vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether. Aromatic vinyl compounds: For example, styrene, α-methylstyrene, vinyltoluene, etc. Olefins: For example, ethylene, butadiene, isoprene, isobutylene, etc. (Meth)acrylic acid esters having alicyclic hydrocarbon groups: For example, alicyclic hydrocarbon group-containing (meth)acrylates such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and adamantyl (meth)acrylate. (Meth)acrylic acid esters having aromatic hydrocarbon groups: for example, aromatic hydrocarbon group-containing (meth)acrylates such as phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate. Other examples include heterocyclic (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate, halogen-containing (meth)acrylates such as vinyl chloride and fluorine-containing (meth)acrylates, silicon-containing (meth)acrylates such as silicone (meth)acrylate, and (meth)acrylic acid esters obtained from terpene compound derivative alcohols.

[0087] When using such copolymerizable monomers, the amount used is not particularly limited, but it is appropriate to use at least 0.01% by weight of the total monomer components. From the viewpoint of better demonstrating the effects of using copolymerizable monomers, the amount of copolymerizable monomer used may be 0.1% by weight or more of the total monomer components, or 0.5% by weight or more. Furthermore, from the viewpoint of easily balancing the adhesive properties, it is appropriate to use at least 50% by weight of the total monomer components, and preferably at least 40% by weight.

[0088] In some embodiments, the monomer components constituting the acrylic polymer (A) may include monomers having nitrogen atoms. The use of monomers having nitrogen atoms can enhance the cohesive force of the adhesive and preferably improve the peel strength after photocuring. A suitable example of a monomer having nitrogen atoms is a monomer having a nitrogen atom-containing ring. Examples of monomers having a nitrogen atom-containing ring include those exemplified above, for example, general formula (1): [ka] An N-vinyl cyclic amide represented by can be used. Here, in general formula (1), R 1 It is a divalent organic group, specifically -(CH2) n - is an integer between 2 and 7 (preferably 2, 3, or 4). Among these, N-vinyl-2-pyrrolidone can be preferably used. Another preferred example of a monomer having a nitrogen atom is (meth)acrylamide.

[0089] The amount of monomer containing nitrogen atoms (preferably monomers having a nitrogen atom-containing ring) used is not particularly limited and may be, for example, 1% or more by weight of the total monomer component, 3% or more by weight, or even 5% or more by weight or 7% or more by weight. In some embodiments, the amount of monomer containing nitrogen atoms used may be 10% or more by weight of the total monomer component, 15% or more by weight, or 20% or more by weight. Furthermore, it is appropriate for the amount of monomer containing nitrogen atoms to be, for example, 40% or less by weight of the total monomer component, but it may also be 35% or less by weight, 30% or less by weight, or 25% or less by weight. In some other embodiments, the amount of monomer containing nitrogen atoms used may be, for example, 20% or less by weight of the total monomer component, or 15% or less by weight.

[0090] In some embodiments, the monomer components constituting the acrylic polymer (A) may include hydroxyl group-containing monomers. The use of hydroxyl group-containing monomers can suitably adjust the cohesive force and degree of crosslinking (e.g., crosslinking with isocyanate crosslinking agents) of the adhesive. The amount of hydroxyl group-containing monomer used is not particularly limited, and may be, for example, 0.01% by weight or more of the total monomer component, 0.1% by weight or more, 0.5% by weight or more, 1% by weight or more, 5% by weight or more, or 10% by weight or more. Furthermore, from the viewpoint of suppressing the water absorption of the adhesive layer, in some embodiments, the amount of hydroxyl group-containing monomer used may be, for example, 40% by weight or less of the total monomer component, for example, 30% by weight or less, 25% by weight or less, or 20% by weight or less. In some other embodiments, the amount of hydroxyl group-containing monomer used may be, for example, 15% by weight or less of the total monomer component, for example, 10% by weight or less, or 5% by weight or less.

[0091] In some embodiments, the proportion of carboxyl group-containing monomers in the monomer component of the acrylic polymer (A) may be, for example, 2% by weight or less, 1% by weight or less, or 0.5% by weight or less (for example, less than 0.1% by weight). The acrylic polymer (A) may not substantially use carboxyl group-containing monomers as a monomer component. Here, substantially not using carboxyl group-containing monomers means not using them at least intentionally. An adhesive layer containing an acrylic polymer (A) in which the amount of carboxyl group-containing monomers used is limited as described above is preferred from the viewpoint of preventing metal corrosion. An adhesive sheet having such an adhesive layer can also be preferably used, for example, in a manner in which the adhesive layer is in contact with an adherend having a metal material.

[0092] In some embodiments, the monomer components constituting the acrylic polymer (A) may include alicyclic hydrocarbon group-containing (meth)acrylate. This can enhance the cohesive force of the adhesive and improve the peel strength after photocuring. Examples of alicyclic hydrocarbon group-containing (meth)acrylates that can be used include those exemplified above, and for example, cyclohexyl acrylate and isobornyl acrylate are preferably used. When using alicyclic hydrocarbon group-containing (meth)acrylate, the amount used is not particularly limited and can be, for example, 1% or more by weight, 3% or more by weight, or 5% or more by weight of the total monomer components. In some embodiments, the amount of alicyclic hydrocarbon group-containing (meth)acrylate used may be 10% or more by weight of the total monomer components, or 15% or more by weight. The upper limit of the amount of alicyclic hydrocarbon group-containing (meth)acrylate used is appropriately about 40% or less by weight, for example, it may be 30% or less by weight, or 25% or less by weight (for example, 15% or less by weight, and even 10% or less by weight).

[0093] The polymerization method used to form (synthesize) polymer (A) from monomer components is not particularly limited, and various conventionally known polymerization methods can be appropriately employed. For example, polymerization methods such as thermal polymerization (typically carried out in the presence of a thermal polymerization initiator), including solution polymerization, emulsion polymerization, and bulk polymerization; photopolymerization (typically carried out in the presence of a photopolymerization initiator), which is performed by irradiation with light such as ultraviolet light; and radiation polymerization (typically carried out by irradiation with radiation such as beta rays and gamma rays) can be appropriately employed. Two or more polymerization methods may also be combined (for example, in steps).

[0094] For solution polymerization, one solvent or a mixture of two or more solvents can be used as the solvent (polymerization solvent), for example, aromatic compounds such as toluene (typically aromatic hydrocarbons); esters such as ethyl acetate and butyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; halogenated alkanes such as 1,2-dichloroethane; lower alcohols such as isopropyl alcohol (e.g., monohydric alcohols with 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether; ketones such as methyl ethyl ketone; etc.

[0095] In polymerization, known or conventional thermal polymerization initiators or photopolymerization initiators may be used depending on the polymerization method and polymerization mode. Such polymerization initiators can be used individually or in appropriate combinations of two or more.

[0096] While not particularly limited, the following can be used as thermal polymerization initiators: azo polymerization initiators, peroxide initiators, redox initiators using a combination of peroxide and reducing agent, substituted ethane initiators, etc. More specifically, for example, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2-methylpropionamidine) disulfate, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis(N,N'-dimethyleneisobutylamidine), 2,2'-azobis[N-(2-carboxyethyl)-2- Examples of azo initiators include methylpropionamidine hydrate; persulfates such as potassium persulfate and ammonium persulfate; peroxide initiators such as benzoyl peroxide, t-butyl hydroperoxide, and hydrogen peroxide; substituted ethane initiators such as phenyl-substituted ethane; and redox initiators such as combinations of persulfates and sodium bisulfite, or peroxides and sodium ascorbate; but are not limited to these. Thermal polymerization can preferably be carried out at a temperature of, for example, 20 to 100°C (typically 40 to 80°C), but is not limited to this.

[0097] While not particularly limited, the following can be used as photopolymerization initiators: ketal-based photopolymerization initiators, acetophenone-based photopolymerization initiators, benzoin ether-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and the like.

[0098] The amount of polymerization initiator used can be the usual amount depending on the polymerization method and polymerization mode, and is not particularly limited. For example, approximately 0.001 to 5 parts by weight (typically approximately 0.01 to 2 parts by weight, for example, approximately 0.01 to 1 part by weight) of polymerization initiator can be used per 100 parts by weight of the monomer to be polymerized.

[0099] For the above polymerization, various conventionally known chain transfer agents (which may also be known as molecular weight modifiers or degree of polymerization modifiers) can be used as needed. As chain transfer agents, mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, thioglycolic acid, and α-thioglycerol can be used. Alternatively, chain transfer agents that do not contain sulfur atoms (non-sulfur chain transfer agents) may be used. Specific examples of non-sulfur chain transfer agents include anilines such as N,N-dimethylaniline and N,N-diethylaniline; terpenoids such as α-pinene and terpinolene; styrenes such as α-methylstyrene and α-methylstyrene dimer; compounds having a benzylidenyl group such as dibenzylideneacetone, cinnamyl alcohol, and cinnamylaldehyde; hydroquinones such as hydroquinone and naphthohydroquinone; quinones such as benzoquinone and naphthoquinone; olefins such as 2,3-dimethyl-2-butene and 1,5-cyclooctadiene; alcohols such as phenol, benzyl alcohol, and allyl alcohol; and benzyl hydrogens such as diphenylbenzene and triphenylbenzene. Chain transfer agents can be used individually or in combination of two or more. The technology disclosed herein can also be preferably implemented in a form that does not use chain transfer agents.

[0100] When using a chain transfer agent, the amount used can be approximately 0.005 to 1 part by weight per 100 parts by weight of monomer component. In some embodiments, from the viewpoint of impact resistance, the amount of chain transfer agent used per 100 parts by weight of monomer component can be, for example, 0.01 parts by weight or more, 0.03 parts by weight or more, 0.05 parts by weight or more, or 0.07 parts by weight or more. Also, in some embodiments, from the viewpoint of deformation resistance, the amount of chain transfer agent used per 100 parts by weight of monomer component can be, for example, 0.5 parts by weight or less, 0.2 parts by weight or less, 0.1 parts by weight or less, or less than 0.1 parts by weight (for example, 0.09 parts by weight or less).

[0101] In the technologies disclosed herein, the glass transition temperature (Tg) of polymer (A) is not particularly limited, but is suitable to be less than 0°C, preferably less than -10°C, and preferably less than -20°C. The impact resistance tends to improve as the Tg of polymer (A) decreases. In some embodiments, the Tg of polymer (A) may be less than -25°C or less than -30°C. Also, the Tg of polymer (A) is typically -80°C or higher, for example, may be -70°C or higher, may be -60°C or higher, or may be -55°C or higher. From the viewpoint of increasing the elastic modulus, in some embodiments, the Tg of polymer (A) is preferably -50°C or higher, more preferably -45°C or higher, may be -40°C or higher, may be -38°C or higher, or may be -35°C or higher.

[0102] Herein, in this specification, the Tg of a polymer refers to the Tg determined by Fox's formula based on the composition of the monomer components used in the preparation of the polymer. Fox's formula, as shown below, is a relationship between the Tg of a copolymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer. 1 / Tg = Σ(Wi / Tgi)

[0103] In Fox's equation above, Tg represents the glass transition temperature of the copolymer (unit: K), Wi represents the weight fraction of monomer i in the copolymer (weight-based copolymerization ratio), and Tgi represents the glass transition temperature of the monomer i homopolymer (unit: K). If the polymer for which Tg is to be specified is a homopolymer, the Tg of the homopolymer and the Tg of the target polymer are the same.

[0104] The glass transition temperature of the homopolymer used in calculating Tg shall be the value specified in publicly available documents. For example, for the monomers listed below, the following values ​​shall be used as the glass transition temperature of the homopolymer of the monomer. n-butyl acrylate -55℃ 2-Ethylhexyl acrylate -70℃ Isostearyl acrylate -18℃ Cyclohexyl acrylate 15℃ N-vinyl-2-pyrrolidone 54℃ 2-Hydroxyethyl acrylate -15℃ 4-Hydroxybutyl acrylate -40℃

[0105] For the glass transition temperatures of monomer homopolymers other than those exemplified above, the values ​​listed in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) shall be used. If multiple values ​​are listed in this document, the highest value shall be adopted.

[0106] The weight-average molecular weight (Mw) of polymer (A) is not particularly limited. From the viewpoint of achieving a good balance between deformation resistance and impact resistance, in some embodiments, the Mw of polymer (A) is, for example, approximately 10 × 10 4 The above is appropriate, 20 × 10 4 It is preferable that it be greater than 30 × 10 4 Super is fine, 40 x 10 4 Super is fine, 50 x 10 4 It can also be "super". Also, the upper limit of Mw for polymer (A) is approximately 500 × 10 4 The following is possible. In some embodiments, from the viewpoint of adhesion to the adherend and peel strength, the Mw of polymer (A) is, for example, 300 × 10 4 The following may be used: 150 × 10 4 The following is also acceptable: 100 x 10 4 The following is also acceptable: 90 x 10 4 The following is also acceptable: 75 x 10 4 The following is also acceptable. The above examples of Mw may apply to the Mw of polymer (A) in the adhesive layer of the adhesive sheet disclosed herein, or to the Mw of polymer (A) in the adhesive composition used to form the adhesive layer.

[0107] Mw refers to the value obtained by gel permeation chromatography (GPC) in terms of standard polystyrene equivalent. For the GPC device, for example, the "HLC-8220GPC" (manufactured by Tosoh Corporation) or an equivalent product can be used. The following methods are used as GPC measurement conditions. In the examples described later, Mw is measured using the following method. (GPC measurement conditions) Equipment: Tosoh Corporation, HLC-8220GPC column: Sample columns: Tosoh Corporation, TSKguardcolumn Super HZ-H (1 tube) + TSKgel Super HZM-H (2 tubes) Reference column: TSKgel Super H-RC (1 tube), manufactured by Tosoh Corporation. Flow rate: 0.6mL / min Injection volume: 10μL Column temperature: 40℃ Eluent:THF Injection sample concentration: 0.2% by weight Detector: Differential refractometer The weight-average molecular weight is calculated on a polystyrene basis.

[0108] (Photoreactive monomer (B)) In some preferred embodiments, the adhesive layer may include a photoreactive monomer (B) in addition to the polymer (A) described above (e.g., acrylic polymer (A)). As the photoreactive monomer (B), a compound having two or more ethylenically unsaturated groups (hereinafter also referred to as "number of functional groups") in the molecule can be used. There is no particular upper limit to the number of functional groups of the compound used as the photoreactive monomer (B). The number of functional groups may be, for example, 50 or less, 40 or less, 30 or less, 20 or less, or 15 or less. In some embodiments, a compound having, for example, 2 to 10 ethylenically unsaturated groups can be used, preferably a compound with 2 to 8 functional groups, and more preferably a compound with 2 to 6 functional groups. The photoreactive monomer (B) can be used alone or in combination of two or more.

[0109] The photoreactive monomer (B) contained in the adhesive layer can form a crosslinked structure by reacting with the ethylenically unsaturated groups after application to the substrate by irradiation with light (e.g., ultraviolet light). An adhesive sheet containing the photoreactive monomer (B) in the adhesive layer can have its deformation resistance improved by curing the adhesive layer with ultraviolet light after application to the substrate. This allows for a favorable balance between good conformability to the surface shape of the substrate during application and high deformation resistance after application.

[0110] The above examples of ethylenically unsaturated groups include, but are not limited to, acryloyl, methacryloyl, vinyl, and allyl groups. The two or more ethylenically unsaturated groups in the photoreactive monomer (B) may be the same group or two or more different groups. From the viewpoint of photoreactivity, preferred ethylenically unsaturated groups include acryloyl and methacryloyl groups. Among these, acryloyl groups are preferred.

[0111] The functional group equivalent of the compound used as the photoreactive monomer (B) is not particularly limited. The above functional group equivalent may be, for example, about 50 to 10,000 g / mol, about 50 to 8,000 g / mol, about 50 to 5,000 g / mol, about 50 to 3,000 g / mol, or about 50 to 2,000 g / mol. In some embodiments, from the viewpoint of photocurability, a compound having a functional group equivalent of about 60 to 800 g / mol (more preferably about 80 to 600 g / mol) can be preferably used as the photoreactive monomer (B).

[0112] The functional group equivalent of photoreactive monomer (B) is calculated by dividing the molecular weight [g / mol] of photoreactive monomer (B) by the number of ethylene unsaturated functional groups it possesses. The molecular weight of photoreactive monomer (B) can be obtained, for example, by the GPC method as the weight-average molecular weight on a standard polystyrene basis. Alternatively, the molecular weight [g / mol] of photoreactive monomer (B) may be the manufacturer's stated value or the molecular weight calculated from the molecular structure.

[0113] The molecular weight of the photoreactive monomer (B) is not particularly limited and can be selected so as to suitably exhibit the desired effect. For example, a photoreactive monomer (B) with a molecular weight of approximately 20,000 or less can be used. From the viewpoint of ease of preparation and coating properties of the adhesive composition, in some embodiments, the molecular weight of the photoreactive monomer (B) may be, for example, 16,000 or less, 10,000 or less, 4,000 or less, 1,500 or less, or 1,000 or less. The molecular weight of the photoreactive monomer (B) is, for example, 100 or more, and is typically 120 or more. From the viewpoint of processability and handling properties of the adhesive sheet, in some embodiments, the molecular weight of the photoreactive monomer (B) may be, for example, 150 or more, 200 or more, 280 or more, 350 or more, 420 or more, 480 or more, or 550 or more.

[0114] In the adhesive sheet disclosed herein, the amount of photoreactive monomer (B) contained in the adhesive layer is not particularly limited and can be appropriately set according to the target performance (e.g., the elastic modulus of the adhesive layer after photocuring). In some embodiments in which the adhesive layer contains polymer (A) and photoreactive monomer (B), the amount of photoreactive monomer (B) per 100 parts by weight of polymer (A) contained in the adhesive layer may be, for example, 1 part by weight or more, and preferably 3 parts by weight or more. From the viewpoint of making it easier to increase the elastic modulus of the adhesive layer after photocuring, the amount of photoreactive monomer (B) per 100 parts by weight of polymer (A) may be 5 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, or 20 parts by weight or more. Furthermore, from the viewpoint of the cohesiveness of the adhesive layer before photocuring and the handling (e.g., processability) of the adhesive sheet, the amount of photoreactive monomer (B) per 100 parts by weight of polymer (A) is appropriate to be 80 parts by weight or less, preferably 60 parts by weight or less, and may also be 50 parts by weight or less, 40 parts by weight or less, or 35 parts by weight or less.

[0115] In some embodiments, the adhesive layer preferably contains at least a compound B1 as the photoreactive monomer (B), which has a ring structure and two or more ethylenically unsaturated groups in its molecule. An adhesive layer containing a compound B1 with such a structure can effectively increase the deformation resistance of the adhesive layer upon light irradiation. The ring in the ring structure may be an aliphatic ring or an aromatic ring. The ring may also be a carbon ring or a heterocycle. The number of rings contained in one molecule of compound B1 may be one or two or more. There is no particular upper limit to the number of rings contained in compound B1; for example, it may be 100 or less, 70 or less, 50 or less, 30 or less, 15 or less, 8 or less, 6 or less, 5 or less, or 4 or less. If compound B1 contains two or more rings, these rings may or may not form a fused ring (typically a bicyclic or tricyclic fused ring). The above-mentioned ring is preferably included in the main chain of compound B1. That is, it is preferable that one ethylenically unsaturated group of compound B1 and at least one other ethylenically unsaturated group are linked via the above-mentioned ring structure. Compound B1 can be used alone or in combination of two or more types.

[0116] As compound B1, a compound having a ring structure and two or more ethylenically unsaturated groups within the molecule, and having a functional group equivalent of 100 g / mol or more, can preferably be used. An adhesive sheet containing compound B1 satisfying the above functional group equivalent in the adhesive layer can suitably form a bond with high deformation resistance and high impact resistance. The reason for obtaining such effects is not to be interpreted in a particularly restrictive way, but it is thought that compound B1 can effectively increase the elastic modulus of the adhesive layer after light irradiation due to the rigidity of the ring structure, thereby imparting deformation resistance, while the functional group equivalent of compound B1 being above a predetermined level maintains the distance between crosslinking points, thereby forming a crosslinked structure with high impact resistance. In some embodiments, the functional group equivalent of compound B1 may be, for example, 120 g / mol or more, 150 g / mol or more, 180 g / mol or more, 230 g / mol or more, 280 g / mol or more, 320 g / mol or more, or 350 g / mol or more. Impact resistance tends to improve with increasing functional group equivalent of compound B1. The functional group equivalent of compound B1 may be, for example, 10,000 g / mol or less, 8,000 g / mol or less, 5,000 g / mol or less, 3,000 g / mol or less, or 2,000 g / mol or less. In some embodiments, from the viewpoint of photocurability, etc., the functional group equivalent of compound B1 is preferably 800 g / mol or less, and more preferably 600 g / mol or less. In some embodiments, the functional group equivalent of compound B1 may be 500 g / mol or less, 400 g / mol or less, or 300 g / mol or less.

[0117] In some embodiments, the number of functional groups in compound B1 may be, for example, 2 to 50, 2 to 40, 2 to 30, 2 to 10, preferably 2 to 6, 2 to 4, or 2 to 3. In some embodiments, compound B1 having 2 functional groups may be preferred.

[0118] Compound B1 may have functional groups other than ethylenically unsaturated groups. Examples of functional groups other than ethylenically unsaturated groups include hydroxyl groups, carboxyl groups, and amino groups. Preferred examples of functional groups other than ethylenically unsaturated groups include hydroxyl groups and amino groups.

[0119] Examples of compound B1 include bisphenol A type epoxy (meth)acrylates such as bisphenol A glycidyl ether (meth)acrylic acid adduct, bisphenol A glycidylamine (meth)acrylic acid adduct, and bisphenol A glycidyl ester (meth)acrylic acid adduct; alkylene oxide modified bisphenol A (meth)acrylates such as ethylene oxide (EO) modified bisphenol A di(meth)acrylate and propylene oxide (PO) modified bisphenol A di(meth)acrylate; bisphenol F type epoxy (meth)acrylates such as bisphenol F glycidyl ether (meth)acrylic acid adduct, bisphenol F glycidylamine (meth)acrylic acid adduct, and bisphenol F glycidyl ester (meth)acrylic acid adduct; alkylene oxide modified bisphenol F (meth)acrylates such as EO modified bisphenol F di(meth)acrylate and PO modified bisphenol F di(meth)acrylate; bisphenol E glycidyl ether (meth)acrylic acid adduct, and bisphenol E Bisphenol E type epoxy (meth)acrylates such as glycidylamine (meth)acrylate adducts and bisphenol E glycidyl ester (meth)acrylate adducts; alkylene oxide modified bisphenol E (meth)acrylates such as EO-modified bisphenol E di(meth)acrylate and PO-modified bisphenol E di(meth)acrylate; 9,9-bis(4-hydroxyphenyl)full orange (meth)acrylate, 9,9-bis[4-(2-hydroxyethoxy)phenyl]full orange (meth)acrylate (Meth)acrylates containing a fluorene skeleton, such as rilate; tricyclodecane dimethanol di(meth)acrylate, hydrogenated bisphenol A type epoxy(meth)acrylate, hydrogenated bisphenol F type epoxy(meth)acrylate, hydrogenated bisphenol E type epoxy(meth)acrylate, hydrogenated phthalate type epoxy(meth)acrylate, hydrogenated terpenephenol(meth)acrylate, 1,4-cyclohexanedimethanol diglycidyl ether(meth)acrylate, etc., which may be aliphatic rings (or alicyclic condensed rings).Examples of (meth)acrylates having ); (meth)acrylic acid adducts of novolac-type epoxy resins; (meth)acrylic acid adducts of thioether-type epoxy resins; (meth)acrylic acid adducts of naphthalene-type epoxy resins; (meth)acrylic acid adducts of dicyclopentadiene-type epoxy resins; (meth)acrylic acid adducts of alkyldiphenol-type epoxy resins; (meth)acrylic acid adducts of biphenyl-type epoxy resins; (meth)acrylic acid adducts of terpenephenol resins; isocyanurate-type (meth)acrylates such as tris(2-hydroxyethyl)isocyanurate di(meth)acrylate and tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate; divinylbenzene; hydroquinone di(meth)acrylate; resorcinol di(meth)acrylate; modified versions of any of the above materials (e.g., amine-modified, acid-modified, halogen-modified); etc., but not limited to these. In some embodiments, compound B1 having an aromatic carbon ring can be preferably used. Preferred examples of compound B1 include compounds containing a bisphenol A structure, such as bisphenol A type epoxy (meth)acrylate, alkylene oxide-modified bisphenol A (meth)acrylate, and their modified products (e.g., amine-modified products).

[0120] Commercially available products that can be used as compound B1 include, but are not limited to, the following: "A-DCP" and "A-BPE-4" from Shin-Nakamura Chemical Industry Co., Ltd., "Viscote #540" and "Viscote #700HV" from Osaka Organic Chemical Industry Co., Ltd., "R-114F" from Nippon Kayaku Co., Ltd., "Epoxy Ester 3000A" and "Epoxy Ester 80MFA" from Kyoeisha Chemical Co., Ltd., and "EBECRYL 3700," "EBECRYL 3703," and "EBECRYL 3603" from Daicel Ornex Co., Ltd.

[0121] The amount of compound B1 per 100 parts by weight of polymer (A) contained in the adhesive layer is not particularly limited and can be, for example, 0.5 parts by weight or more. From the viewpoint of making it easier to obtain an adhesive layer that balances deformation resistance and impact resistance well, in some embodiments, the amount of compound B1 per 100 parts by weight of polymer (A) may be, for example, 1 part by weight or more, 3 parts by weight or more, 5 parts by weight or more, 7 parts by weight or more, 10 parts by weight or more, or 15 parts by weight or more. Furthermore, from the viewpoint of the cohesiveness of the adhesive layer before photocuring and the handling of the adhesive sheet, the amount of compound B1 per 100 parts by weight of polymer (A) is appropriate to be 80 parts by weight or less, preferably 60 parts by weight or less, may be 50 parts by weight or less, may be 40 parts by weight or less, may be 35 parts by weight or less, may be 25 parts by weight or less, or may be 15 parts by weight or less.

[0122] In some embodiments, the adhesive layer may contain, as the photoreactive monomer (B), compound B2 having two or more functional groups and no ring structure within the molecule. Compound B2 is preferably used in combination with compound B1. This adjusts the crosslinking structure of the adhesive layer, making it possible to form a bond that more favorably balances deformation resistance and impact resistance. Compound B2 can be used alone or in combination of two or more types.

[0123] The number of functional groups in compound B2 may be, for example, 50 or less, 40 or less, 30 or less, 20 or less, or 15 or less. In some embodiments, the number of functional groups in compound B2 may be, for example, 2 to 10, preferably 3 to 10, 3 to 8, or 4 to 6. For example, in embodiments where compound B1 is a compound with 2 functional groups, it may be advantageous to use compound B2 with 3 or more functional groups (preferably 4 or more, more preferably 5 or more, and even more preferably 6 or more).

[0124] The functional group equivalent of compound B2 is not particularly limited and may be, for example, 5000 g / mol or less, 2000 g / mol or less, or 1000 g / mol or less. In some embodiments, the functional group equivalent of compound B2 may be, for example, 600 g / mol or less, and may be 400 g / mol or less, 300 g / mol or less, 200 g / mol or less, 150 g / mol or less, or 100 g / mol or less from the viewpoint of improving photocurability and the hardness of the cured product. The functional group equivalent of compound B2 is typically 50 g / mol or more, preferably 60 g / mol or more, may be 70 g / mol or more, may be 80 g / mol or more, or may be 90 g / mol or more.

[0125] Examples of compounds that can be used as compound B2 include, but are not limited to, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, trimethylolethane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, neopentyl glycol di(meth)acrylate, hydroxypivalate neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, allyl(meth)acrylate, vinyl(meth)acrylate, EO-modified or PO-modified versions of any of the above materials, etc.

[0126] In embodiments using compound B2, the amount of compound B2 per 100 parts by weight of polymer (A) contained in the adhesive layer is not particularly limited and can be, for example, 0.1 parts by weight or more. From the viewpoint of making it easier to obtain an adhesive layer that balances deformation resistance and impact resistance well, in some embodiments, the amount of compound B2 per 100 parts by weight of polymer (A) may be, for example, 1 part by weight or more, 2 parts by weight or more, 4 parts by weight or more, 6 parts by weight or more, 10 parts by weight or more, or 12 parts by weight or more. Furthermore, from the viewpoint of suppressing a decrease in adhesion to the adherend due to excessive crosslinking, in some embodiments, the amount of compound B2 per 100 parts by weight of polymer (A) is, for example, suitable to be 25 parts by weight or less, preferably 17 parts by weight or less, may be 15 parts by weight or less, may be 13 parts by weight or less, or may be 9 parts by weight or less.

[0127] In embodiments where compound B1 and compound B2 are used in combination, compound B2 may preferably be a compound having 3 or more functional groups and having a smaller functional group equivalent than compound B1 used in combination with it. In some embodiments, the ratio of the functional group equivalent FE2 of compound B2 to the functional group equivalent FE1 of compound B1 (FE2 / FE1) may be, for example, 0.9 or less, 0.7 or less, 0.5 or less, or 0.4 or less. According to such embodiments, the effect of improving the elastic modulus by the photoreactive monomer (B) can be efficiently exerted. The lower limit of the above ratio (FE2 / FE1) is not particularly limited and may be, for example, 0.01 or more, 0.1 or more, or 0.2 or more.

[0128] In embodiments where compound B1 and compound B2 are used in combination, the weight ratio (W2 / W1) of the amount of compound B2 used W2 to the amount of compound B1 used W1 is not particularly limited. In some embodiments, the weight ratio (W2 / W1) may be, for example, 0.05 to 10, 0.1 to 5, 0.2 to 3, or 0.3 to 2. By setting the weight ratio (W2 / W1) to any of the above ranges, the effects of using compound B1 and compound B2 in combination tend to be favorably exhibited.

[0129] In some other embodiments using a photoreactive monomer (B) (typically compound B2), the amount of photoreactive monomer (B) (typically compound B2) used can be approximately 3% by weight or less of the monomer component of the polymer (A), preferably approximately 2% by weight or less, and more preferably approximately 1% by weight or less (e.g., approximately 0.5% by weight or less). The lower limit of the amount used when using photoreactive monomer (B) (typically compound B2) is not particularly limited, as long as it is greater than 0% by weight. It is appropriate to use an amount of photoreactive monomer (B) (typically compound B2) of approximately 0.001% by weight or more (e.g., approximately 0.01% by weight or more) of the monomer component.

[0130] In some embodiments, the photoreactive monomer (B) may be included in the adhesive layer in a free form. Such an adhesive layer can be suitably formed using an adhesive composition containing the photoreactive monomer (B) in a free form. Here, "free form" means that the photoreactive monomer (B) is not chemically bonded to other components (e.g., polymer (A)) contained in the adhesive layer or adhesive composition. Adhesive compositions containing the photoreactive monomer (B) in a free form may be advantageous in terms of ease of preparation and suppression of gelation.

[0131] In several other forms, at least a portion of the photoreactive monomer (B) may be included in the adhesive layer in a form chemically bonded to other components (e.g., polymer (A), crosslinking agent described later) in the adhesive layer or adhesive composition, from the viewpoint of improving the processability of the adhesive sheet. The above chemical bond may be, for example, a bond formed by the reaction of a functional group F1 other than an ethylenically unsaturated group that the photoreactive monomer (B) has in its molecule and a functional group F2 that has in the molecule of the other component and is capable of reacting with the functional group F1. The above other component may be a crosslinking agent, and the photoreactive monomer (B) may be bonded to polymer (A) via the crosslinking agent.

[0132] (Acrylic oligomers) The adhesive layer of the adhesive sheet disclosed herein may contain an acrylic oligomer for the viewpoint of improving cohesive force and adhesion to surfaces adjacent to the adhesive layer (for example, the surface of the support substrate in the adhesive sheet, the surface of the object to which the adhesive sheet is attached, etc.). The adhesive layer containing the acrylic oligomer can preferably be formed using an adhesive composition containing the acrylic oligomer. As the acrylic oligomer, one having a higher Tg than the polymer (A) described above can preferably be used.

[0133] The Tg of the above acrylic oligomer is not particularly limited and may be, for example, between approximately 20°C and 300°C. The above Tg may be, for example, above approximately 30°C, above approximately 40°C, above approximately 60°C, above approximately 80°C, or above approximately 100°C. Generally, as the Tg of the acrylic oligomer increases, the effect of improving cohesive force tends to increase. Furthermore, from the viewpoint of anchoring ability to the supporting substrate and shock absorption, the Tg of the acrylic oligomer may be, for example, below approximately 250°C, below approximately 200°C, below approximately 180°C, or below approximately 150°C. Note that the Tg of the acrylic oligomer is a value calculated based on Fox's formula, just like the Tg of polymer (A).

[0134] The Mw of the acrylic oligomer is not particularly limited; for example, it may be approximately 1000 or more, approximately 1500 or more is appropriate, approximately 2000 or more, or approximately 3000 or more. Furthermore, the Mw of the acrylic oligomer may be approximately less than 30000, approximately less than 10000 is appropriate, approximately less than 7000, or approximately less than 5000. When the Mw is within the above range, the effect of improving the cohesiveness of the adhesive layer and adhesion to adjacent surfaces is favorably exhibited. The Mw of the acrylic oligomer can be measured by GPC and determined as a value equivalent to standard polystyrene. Specifically, for example, it can be measured using an HPLC8020 manufactured by Tosoh Corporation with two TSKgelGMH-H(20) columns at a flow rate of approximately 0.5 mL / min using tetrahydrofuran solvent.

[0135] The monomer components that make up the acrylic oligomers are the various (meth)acrylic acid C compounds mentioned above. 1-20 Examples of (meth)acrylate monomers include alkyl esters; various alicyclic hydrocarbon group-containing (meth)acrylates mentioned above; various aromatic hydrocarbon group-containing (meth)acrylates mentioned above; and (meth)acrylates obtained from terpene compound derivative alcohols. These can be used individually or in combination of two or more.

[0136] From the viewpoint of improving adhesion, it is preferable that acrylic oligomers contain relatively bulky acrylic monomers as monomer units, such as alkyl(meth)acrylates with branched alkyl groups like isobutyl(meth)acrylate and t-butyl(meth)acrylate; alicyclic hydrocarbon group-containing(meth)acrylates; and aromatic hydrocarbon group-containing(meth)acrylates. Furthermore, when ultraviolet light is used during the synthesis of acrylic oligomers or the preparation of adhesive layers, monomers having saturated hydrocarbon groups at the ester terminus are preferred because they are less likely to inhibit polymerization. For example, alkyl(meth)acrylates with branched alkyl groups and saturated alicyclic hydrocarbon group-containing(meth)acrylates can be suitably used.

[0137] The proportion of (meth)acrylate monomers in the total monomer components constituting the acrylic oligomer is typically more than 50% by weight, preferably 60% by weight or more, more preferably 70% by weight or more (e.g., 80% by weight or more, and even more than 90% by weight or more). In some preferred embodiments, the acrylic oligomer has a monomer composition consisting substantially of only one or more (meth)acrylate monomers. The monomer components include alicyclic hydrocarbon group-containing (meth)acrylate and (meth)acrylic acid C 1-20 When alkyl esters are included, their weight ratio is not particularly limited. In some embodiments, alicyclic hydrocarbon group-containing (meth)acrylate / (meth)acrylic acid C 1-20The weight ratio of alkyl esters can be, for example, 10 / 90 or more, 20 / 80 or more, or 30 / 70 or more, and can also be 90 / 10 or less, 80 / 20 or less, or 70 / 30 or less.

[0138] In addition to the (meth)acrylate monomers mentioned above, functional group-containing monomers can be used as constituent monomers of acrylic oligomers as needed. Examples of functional group-containing monomers include monomers having nitrogen atom-containing heterocycles such as N-vinyl-2-pyrrolidone and N-acryloylmorpholine; monomers containing amino groups such as N,N-dimethylaminoethyl (meth)acrylate; monomers containing amide groups such as N,N-diethyl (meth)acrylamide; monomers containing carboxyl groups such as AA and MAA; and monomers containing hydroxyl groups such as 2-hydroxyethyl (meth)acrylate. These functional group-containing monomers can be used individually or in combination of two or more. When functional group-containing monomers are used, the proportion of functional group-containing monomers in the total monomer components constituting the acrylic oligomer can be, for example, 1% or more by weight, 2% or more by weight, or 3% or more by weight, and can also be, for example, 15% or less by weight, 10% or less by weight, or 7% or less by weight. Acrylic oligomers may also be those that do not use functional group-containing monomers.

[0139] Suitable acrylic oligomers include, for example, homopolymers of dicyclopentanyl methacrylate (DCPMA), cyclohexyl methacrylate (CHMA), isobornyl methacrylate (IBXMA), isobornyl acrylate (IBXA), dicyclopentanyl acrylate (DCPA), 1-adamantyl methacrylate (ADMA), and 1-adamantyl acrylate (ADA), as well as copolymers of DCPMA and MMA, copolymers of DCPMA and IBXMA, copolymers of ADA and methyl methacrylate (MMA), copolymers of CHMA and isobutyl methacrylate (IBMA), copolymers of CHMA and IBXMA, copolymers of CHMA and acryloylmorpholine (ACMO), copolymers of CHMA and diethylacrylamide (DEAA), copolymers of CHMA and AA, and the like.

[0140] Acrylic oligomers can be formed by polymerizing their constituent monomer components. The polymerization method and polymerization mode are not particularly limited, and various conventionally known polymerization methods (e.g., solution polymerization, emulsion polymerization, bulk polymerization, photopolymerization, radiation polymerization, etc.) can be employed in appropriate manner. The types of polymerization initiators that can be used as needed (e.g., azo polymerization initiators) are generally as exemplified for the synthesis of acrylic polymer (A), and the amount of polymerization initiator and the amount of chain transfer agent (e.g., mercaptans) used as needed are appropriately set based on common technical knowledge to achieve the desired molecular weight, so a detailed explanation is omitted.

[0141] When an acrylic oligomer is included in the adhesive layer or adhesive composition, its content can be, for example, 0.01 parts by weight or more per 100 parts by weight of polymer (A), and may be 0.05 parts by weight or more, or 0.1 parts by weight or more, or 0.2 parts by weight or more, from the viewpoint of obtaining a higher effect. Furthermore, from the viewpoint of compatibility with polymer (A), it is appropriate that the content of the acrylic oligomer per 100 parts by weight of polymer (A) be less than 50 parts by weight, preferably less than 30 parts by weight, more preferably 25 parts by weight or less, and may be, for example, 10 parts by weight or less, or 5 parts by weight or less, or 1 part by weight or less. An adhesive layer or adhesive composition that does not contain an acrylic oligomer is also acceptable.

[0142] (Crosslinking agent) A crosslinking agent may be used in the adhesive layer as needed. In the adhesive sheet disclosed herein, the crosslinking agent is typically included in the adhesive layer in the form after the crosslinking reaction. By using a crosslinking agent, the cohesive force of the adhesive layer can be appropriately adjusted. Furthermore, for example, in an adhesive sheet containing a photoreactive monomer (B) in the adhesive layer, by using a combination of the crosslinking agent and the photoreactive monomer (B), it is possible to suitably achieve both the flexibility of the adhesive layer before photocuring of the photoreactive monomer and the deformation resistance of the adhesive layer after photocuring.

[0143] The type of crosslinking agent is not particularly limited, and can be selected from conventionally known crosslinking agents, for example, depending on the composition of the adhesive composition, so that the crosslinking agent exhibits appropriate crosslinking function within the adhesive layer. Examples of crosslinking agents that can be used include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, carbodiimide-based crosslinking agents, melamine-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, hydrazine-based crosslinking agents, amine-based crosslinking agents, and the like. These can be used individually or in combination of two or more.

[0144] As isocyanate crosslinking agents, polyfunctional isocyanate compounds with two or more functions can be used. Examples include aromatic isocyanates such as tolylene diisocyanate, xylene diisocyanate, polymethylene polyphenyl diisocyanate, tris(p-isocyanatophenyl)thiophosphate, and diphenylmethane diisocyanate; alicyclic isocyanates such as isophorone diisocyanate; and aliphatic isocyanates such as hexamethylene diisocyanate. Examples of commercially available products include isocyanate adducts such as trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, product name "Coronate L"), trimethylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, product name "Coronate HL"), isocyanurate of hexamethylene diisocyanate (manufactured by Tosoh Corporation, product name "Coronate HX"), and trimethylolpropane / xylylene diisocyanate adduct (manufactured by Mitsui Chemicals, product name "Takenate D-110N").

[0145] As an epoxy crosslinking agent, any agent having two or more epoxy groups in one molecule can be used without particular limitation. Epoxy crosslinking agents having 3 to 5 epoxy groups in one molecule are preferred. Specific examples of epoxy crosslinking agents include N,N,N',N'-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, and polyglycerol polyglycidyl ether. Commercially available epoxy crosslinking agents include "TETRAD-X" and "TETRAD-C" from Mitsubishi Gas Chemical Company, "Epiclon CR-5L" from DIC Corporation, "Denacol EX-512" from Nagase ChemteX Corporation, and "TEPIC-G" from Nissan Chemical Industries, Ltd.

[0146] As an oxazoline crosslinking agent, any agent having one or more oxazoline groups in one molecule can be used without particular limitation. Examples of aziridine crosslinking agents include trimethylolpropantris[3-(1-aziridinyl)propionate] and trimethylolpropantris[3-(1-(2-methyl)aziridinylpropionate)]. As the carbodiimide crosslinking agent, low-molecular-weight or high-molecular-weight compounds having two or more carbodiimide groups can be used.

[0147] In some embodiments, peroxides may be used as crosslinking agents. Examples of peroxides include di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxyisobutyrate, and dibenzoyl peroxide. Among these, di(4-t-butylcyclohexyl)peroxydicarbonate, dilauroyl peroxide, and dibenzoyl peroxide are particularly excellent in crosslinking reaction efficiency. When peroxides are used as polymerization initiators, any remaining peroxide that is not used in the polymerization reaction can also be used in the crosslinking reaction. In that case, the amount of remaining peroxide should be quantified, and if the proportion of peroxide is less than a predetermined amount, peroxide should be added as needed to reach the predetermined amount. The quantification of peroxide can be carried out by the method described in Japanese Patent Publication No. 4971517.

[0148] The amount of crosslinking agent used (or the total amount if two or more crosslinking agents are used) is not particularly limited. From the viewpoint of realizing an adhesive that exhibits a good balance of adhesive properties such as adhesion and cohesiveness, it is appropriate to use approximately 5 parts by weight or less of crosslinking agent per 100 parts by weight of polymer (A), but it may also be 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, or less than 1 part by weight. In embodiments in which a crosslinking agent and a photoreactive monomer (B) are used in combination, from the viewpoint of making it easier to suitably exhibit the effects of such combination use, the amount of crosslinking agent used per 100 parts by weight of polymer (A) may be, for example, 0.80 parts by weight or less, 0.60 parts by weight or less, 0.30 parts by weight or less, or 0.10 parts by weight or less. The lower limit of the amount of crosslinking agent used is not particularly limited, and it may be used in an amount greater than 0 parts by weight per 100 parts by weight of polymer (A). In some embodiments, the amount of crosslinking agent used may be, for example, 0.001 parts by weight or more, 0.01 parts by weight or more, or 0.03 parts by weight or more, per 100 parts by weight of polymer (A).

[0149] The technologies disclosed herein can preferably be implemented in a manner in which at least an isocyanate-based crosslinking agent is used as the crosslinking agent. An isocyanate-based crosslinking agent may be used in combination with other crosslinking agents. In the embodiment in which an isocyanate-based crosslinking agent is used, the amount of isocyanate-based crosslinking agent used per 100 parts by weight of polymer (A) may be, for example, 0.005 parts by weight or more, 0.01 parts by weight or more, or 0.03 parts by weight or more. Alternatively, the amount of isocyanate-based crosslinking agent used per 100 parts by weight of polymer (A) may be, for example, 10 parts by weight or less, 5 parts by weight or less, 3 parts by weight or less, less than 2 parts by weight, less than 1 part by weight, less than 0.80 parts by weight, less than 0.60 parts by weight, less than 0.30 parts by weight, less than 0.10 parts by weight, or less than 0.08 parts by weight.

[0150] A crosslinking catalyst may be used to more effectively advance the crosslinking reaction. Examples of crosslinking catalysts include metal-based crosslinking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, ferric narcem, butyltin oxide, and dioctyltin dilaurate. Among these, tin-based crosslinking catalysts such as dioctyltin dilaurate are preferred. The amount of crosslinking catalyst used is not particularly limited. The amount of crosslinking catalyst used can be, for example, approximately 0.0001 parts by weight or more, approximately 0.001 parts by weight or more, approximately 0.005 parts by weight or more, or approximately 1 part by weight or less, approximately 0.1 parts by weight or less, approximately 0.05 parts by weight or less, per 100 parts by weight of polymer (A).

[0151] The adhesive composition used to form the adhesive layer may optionally contain a compound that induces keto-enol tautomerism as a crosslinking retarder. For example, in an adhesive composition containing an isocyanate crosslinking agent or an adhesive composition that may be used with an isocyanate crosslinking agent, a compound that induces keto-enol tautomerism can be preferably used. This can extend the pot life of the adhesive composition. Various β-dicarbonyl compounds can be used as compounds that exhibit keto-enol tautomerism. Specific examples include β-diketones such as acetylacetone and 2,4-hexanedione; acetoacetate esters such as methyl acetoacetate and ethyl acetoacetate; propionyl acetate esters such as ethyl propionylacetate; isobutyryl acetate esters such as ethyl isobutyrylacetate; and malonic acid esters such as methyl malonate and ethyl malonate. Among these, acetylacetone and acetoacetate esters are particularly preferred. The compounds exhibiting keto-enol tautomerism can be used individually or in combination of two or more. The amount of compound that produces keto-enol tautomerism may be, for example, 0.1 parts by weight or more and 20 parts by weight or less per 100 parts by weight of polymer (A), preferably 0.5 parts by weight or more and 15 parts by weight or less, for example 1 part by weight or more and 10 parts by weight or less, or 1 part by weight or more and 5 parts by weight or less.

[0152] (Silane coupling agent) The adhesive layer of the adhesive sheet disclosed herein may optionally contain a silane coupling agent. The use of a silane coupling agent can improve the peel strength of the adhesive sheet from the adherend (e.g., a glass plate). An adhesive layer containing a silane coupling agent can be suitably formed using an adhesive composition containing a silane coupling agent. In such an adhesive composition, the silane coupling agent is preferably included in the adhesive composition in a free form from the viewpoint of suppressing gelation, etc. Furthermore, in some embodiments, the silane coupling agent is preferably included in the adhesive layer of the adhesive sheet disclosed herein in a free form. A silane coupling agent included in the adhesive layer in such a form can effectively contribute to improving the peel strength. Herein, "free form" means that the silane coupling agent is not chemically bonded to other components contained in the adhesive composition or adhesive layer.

[0153] Examples of silane coupling agents include silicon compounds having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane; 3-chloropropyltrimethoxysilane; (meth)acrylic group-containing silane coupling agents such as acetoacetyl group-containing trimethoxysilane, 3-acryloxypropyltrimethoxysilane, and 3-methacryloxypropyltriethoxysilane; and isocyanate group-containing silane coupling agents such as 3-isocyanatetopropyltriethoxysilane. In some embodiments, the above-mentioned effects can be more preferably achieved by employing a silane coupling agent having a trialkoxysilyl group. Among the preferred silane coupling agents, 3-glycidoxypropyltrimethoxysilane and acetoacetyl group-containing trimethoxysilane are exemplified.

[0154] The amount of silane coupling agent used when using a silane coupling agent can be set to obtain the desired effect and is not particularly limited. In some embodiments, the amount of silane coupling agent used may be, for example, 0.001 parts by weight or more per 100 parts by weight of polymer (A), and from the viewpoint of obtaining a higher effect, it may be 0.01 parts by weight or more, 0.05 parts by weight or more, or 0.1 parts by weight or more. Furthermore, from the viewpoint of suppressing gelation of the adhesive composition, it is appropriate to use 3 parts by weight or less per 100 parts by weight of polymer (A), and it may be 1 part by weight or less, or 0.5 parts by weight or less.

[0155] (Photopolymerization initiator) The adhesive layer of the adhesive sheet disclosed herein may contain a photopolymerization initiator as needed for the purpose of improving or imparting photocurability. As the photopolymerization initiator, ketal-based photopolymerization initiators, acetophenone-based photopolymerization initiators, benzoin ether-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, etc., can be used, similar to the photopolymerization initiators exemplified for use in the synthesis of polymer (A). The photopolymerization initiators can be used individually or in appropriate combinations of two or more types.

[0156] Specific examples of ketal-based photopolymerization initiators include 2,2-dimethoxy-1,2-diphenylethane-1-one. Specific examples of acetophenone-based photopolymerization initiators include 1-hydroxycyclohexylphenyl ketone, 4-phenoxydichloroacetophenone, 4-t-butyldichloroacetophenone, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, and methoxyacetophenone. Specific examples of benzoin ether-based photopolymerization initiators include benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, and benzoin isobutyl ether, as well as substituted benzoin ethers such as anisole methyl ether. Specific examples of acylphosphine oxide-based photopolymerization initiators include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide. Specific examples of α-ketol-based photopolymerization initiators include 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one. Specific examples of aromatic sulfonyl chloride-based photopolymerization initiators include 2-naphthalenesulfonyl chloride. Specific examples of photoactive oxime-based photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime. Specific examples of benzoin-based photopolymerization initiators include benzoin. Specific examples of benzyl-based photopolymerization initiators include benzyl. Specific examples of benzophenone-based photopolymerization initiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone. Specific examples of thioxanthone-based photopolymerization initiators include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone.

[0157] The content of the photopolymerization initiator in the adhesive layer is not particularly limited and can be set so as to appropriately exhibit the desired effect. In some embodiments, the content of the photopolymerization initiator can be, for example, approximately 0.005 parts by weight or more, preferably 0.01 parts by weight or more, preferably 0.05 parts by weight or more, and may also be 0.10 parts by weight or more, 0.15 parts by weight or more, or 0.20 parts by weight or more, per 100 parts by weight of polymer (A) contained in the adhesive layer. Increasing the content of the photopolymerization initiator tends to improve the photocurability of the adhesive layer. Furthermore, the content of the photopolymerization initiator per 100 parts by weight of polymer (A) is appropriately 10 parts by weight or less, preferably 7 parts by weight or less, and may also be 5 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, or 1 part by weight or less. Not having too much photopolymerization initiator content can be advantageous from the viewpoint of improving the storage stability of the adhesive sheet (e.g., stability against photodegradation).

[0158] An adhesive layer containing a photopolymerization initiator can typically be formed using an adhesive composition containing the photopolymerization initiator (e.g., a solvent-based adhesive composition). The adhesive composition containing the photopolymerization initiator can be prepared, for example, by mixing the photopolymerization initiator with other components used in the composition. Furthermore, when preparing an adhesive composition using a polymer (A) synthesized (photopolymerized) in the presence of a photopolymerization initiator (e.g., an acrylic polymer (A)), the residue (unreacted material) of the photopolymerization initiator used in the synthesis of polymer (A) may be used as part or all of the photopolymerization initiator contained in the adhesive layer. The same applies when using an acrylic oligomer synthesized in the presence of a photopolymerization initiator, as needed. From the viewpoint of ease of manufacturing control, the adhesive layers disclosed herein can preferably be formed using an adhesive composition prepared by adding the above-described amount of photopolymerization initiator to other components.

[0159] The adhesive layer or adhesive composition of the adhesive sheet disclosed herein may optionally contain, as needed, various additives common in the field of adhesives, such as tackifying resins (e.g., rosin-based, petroleum-based, terpene-based, phenol-based, ketone-based, etc.), viscosity modifiers (e.g., thickeners), leveling agents, plasticizers, fillers, colorants such as pigments and dyes, stabilizers, preservatives, and anti-aging agents. Such additives can be conventionally used by conventional methods and do not particularly characterize the present invention, so a detailed explanation is omitted. Furthermore, the technology disclosed herein can exhibit good adhesive strength without using the tackifying resin described above. For this reason, in some embodiments, the content of the tackifying resin in the adhesive layer or adhesive composition may be, for example, less than 10 parts by weight, or even less than 5 parts by weight, per 100 parts by weight of polymer (A). The content of the tackifying resin may be less than 1 part by weight (for example, less than 0.5 parts by weight), or less than 0.1 parts by weight (0 parts by weight or more and less than 0.1 parts by weight). The adhesive layer or adhesive composition may not contain the tackifying resin.

[0160] From the viewpoint of transparency, it is preferable that the amount of components other than polymer (A) and the photoreactive monomer (B) used as needed in the adhesive layer (and by extension, the adhesive composition used to form the adhesive layer) is limited. In the technology disclosed herein, the amount of components other than polymer (A) and photoreactive monomer (B) in the adhesive layer is approximately 30% by weight or less, appropriately approximately 15% by weight or less, and preferably approximately 12% by weight or less (for example, approximately 10% by weight or less). In adhesive sheets according to some embodiments, the amount of components other than polymer (A) and photoreactive monomer (B) in the adhesive layer may be approximately 5% by weight or less, approximately 3% by weight or less, or approximately 1.5% by weight or less (for example, approximately 1% by weight or less).

[0161] <Form of adhesive composition> The adhesive layer can be formed using an adhesive composition containing monomer components having the above-described composition in the form of polymers, unpolymerized products (i.e., in a form where polymerizable functional groups are unreacted), or mixtures thereof. The above adhesive composition can take various forms, such as a composition containing an adhesive (adhesive component) in an organic solvent (solvent-type adhesive composition), a composition in which the adhesive is dispersed in an aqueous solvent (water-dispersible adhesive composition), a composition prepared to form an adhesive by curing with active energy rays such as ultraviolet light or radiation (active energy ray-curable adhesive composition), or a hot-melt type adhesive composition that is applied in a heated molten state and forms an adhesive when cooled to around room temperature. From the viewpoint of ease of preparation of the adhesive composition and ease of formation of the adhesive layer, solvent-type adhesive compositions can be preferably used in some embodiments. Solvent-type adhesive compositions can preferably be prepared using a polymer (A), which is a polymer obtained by solution polymerization of monomer components.

[0162] In this specification, "active energy rays" refers to energy rays that have the energy to trigger chemical reactions such as polymerization reactions, crosslinking reactions, and initiator decomposition. Examples of active energy rays include light such as ultraviolet rays, visible light, and infrared rays, as well as radiation such as alpha rays, beta rays, gamma rays, electron beams, neutron beams, and X-rays.

[0163] The above adhesive composition typically contains at least a portion of the monomer components of the composition (which may be a portion of the types of monomers or a portion of the quantities) in the form of a polymer. The polymerization method used to form the polymer is not particularly limited, and various conventionally known polymerization methods can be used as appropriate. For example, thermal polymerization such as solution polymerization, emulsion polymerization, and bulk polymerization (typically carried out in the presence of a thermal polymerization initiator); photopolymerization carried out by irradiation with light such as ultraviolet light (typically carried out in the presence of a photopolymerization initiator); and radiation polymerization carried out by irradiation with radiation such as beta rays and gamma rays can be used as appropriate. In these polymerization methods, the mode of polymerization is not particularly limited, and conventionally known monomer supply methods, polymerization conditions (temperature, time, pressure, light irradiation amount, radiation irradiation amount, etc.), and materials other than monomers used (polymerization initiators, surfactants, etc.) can be appropriately selected.

[0164] In polymerization, known or conventional photopolymerization initiators or thermal polymerization initiators may be used depending on the polymerization method and polymerization mode. Examples of photopolymerization initiators and thermal polymerization initiators are as described above, so redundant explanations will be omitted. Such polymerization initiators can be used individually or in appropriate combinations of two or more.

[0165] (An adhesive composition containing polymers and unpolymerized monomer components) Adhesive compositions according to several embodiments include a polymerization product of a monomer mixture containing at least a portion of the monomer components (raw material monomers) of the composition. Typically, the monomer components are contained in the form of a polymer, with the remainder in the form of an unpolymerized product (unreacted monomer). The polymerization product of the monomer mixture can be prepared by polymerizing the monomer mixture at least partially. The polymerization reaction product described above is preferably a partial polymer of the monomer mixture. Such a partial polymer is a mixture of polymers derived from the monomer mixture and unreacted monomers, and typically exhibits a syrup-like (viscous liquid) state. Hereinafter, a partial polymer with such properties may be referred to as "monomer syrup," "polymer syrup," or simply "syrup."

[0166] The polymerization method used to obtain the above-mentioned polymerization reaction product is not particularly limited, and various polymerization methods as described above can be appropriately selected and used. From the viewpoint of efficiency and simplicity, photopolymerization can be preferably employed. With photopolymerization, the polymerization conversion rate of the monomer mixture can be easily controlled by polymerization conditions such as the amount of light irradiation (light intensity).

[0167] The polymerization conversion rate (monomer conversion) of the monomer mixture in the above-mentioned partial polymer is not particularly limited. The polymerization conversion rate can be, for example, approximately 70% by weight or less, and is preferably approximately 60% by weight or less. From the viewpoint of ease of preparation and coating properties of the adhesive composition containing the above-mentioned partial polymer, the polymerization conversion rate is suitable at approximately 50% by weight or less, and is preferably approximately 40% by weight or less (for example, approximately 35% by weight or less). The lower limit of the polymerization conversion rate is not particularly limited, but is typically approximately 1% by weight or more, and is suitable at approximately 5% by weight or more.

[0168] An adhesive composition containing a partially polymerized product of the above monomer mixture can be easily obtained, for example, by partially polymerizing a monomer mixture containing all of the raw material monomers using a suitable polymerization method (e.g., photopolymerization). The adhesive composition containing the above partially polymerized product may contain other components as needed (e.g., photopolymerization initiators, polyfunctional monomers, crosslinking agents, acrylic oligomers described later, etc.). The method of incorporating such other components is not particularly limited; for example, they may be included in the monomer mixture beforehand or added to the above partially polymerized product.

[0169] Furthermore, the adhesive compositions disclosed herein may be in a form in which a complete polymer of a monomer mixture containing some types of monomers among the monomer components (raw material monomers) is dissolved in the remaining types of monomers or their partial polymers. Such forms of adhesive compositions are also included as examples of adhesive compositions containing polymers and unpolymerized monomer components. In this specification, "complete polymer" means a polymerization conversion rate of more than 95% by weight.

[0170] As a curing method (polymerization method) when forming an adhesive from an adhesive composition containing polymers and unpolymerized monomer components, photopolymerization can be preferably employed. In adhesive compositions containing polymerization reaction products prepared by photopolymerization, photopolymerization is particularly preferred as the curing method. Since the polymerization reaction product obtained by photopolymerization already contains a photopolymerization initiator, when further curing the adhesive composition containing this polymerization reaction product to form an adhesive, photocuring is possible without adding a new photopolymerization initiator. Alternatively, the adhesive composition may have a composition in which a photopolymerization initiator is added as needed to the polymerization reaction product prepared by photopolymerization. The added photopolymerization initiator may be the same as or different from the photopolymerization initiator used to prepare the polymerization reaction product. Adhesive compositions prepared by methods other than photopolymerization can be made photocurable by adding a photopolymerization initiator. Photocurable adhesive compositions have the advantage that even thick adhesive layers can be easily formed. In some preferred embodiments, photopolymerization when forming an adhesive from an adhesive composition can be carried out by ultraviolet irradiation. For ultraviolet irradiation, known high-pressure mercury lamps, low-pressure mercury lamps, metal halide lamps, etc., can be used.

[0171] (An adhesive composition containing monomer components in the form of a complete polymer) Adhesive compositions according to several other embodiments include the monomer component of the adhesive composition in the form of a complete polymer. Such adhesive compositions may take the form of, for example, a solvent-type adhesive composition containing an acrylic polymer, which is a complete polymer of the monomer component, in an organic solvent, or a water-dispersible adhesive composition in which the acrylic polymer is dispersed in an aqueous solvent.

[0172] (Thickness of the adhesive layer) The thickness of the adhesive layer is not particularly limited. The thickness of the adhesive layer may be, for example, about 1 μm to 500 μm, and may be, for example, about 3 μm to 500 μm. In some embodiments, the thickness of the adhesive layer is suitable to be 5 μm or more, for example, may be 10 μm or more, preferably 20 μm or more, more preferably 25 μm or more, and may be greater than 25 μm. As the thickness of the adhesive layer increases, the stress distribution ability of the adhesive layer tends to increase. This can advantageously contribute to the reduction of optical distortion. In addition, adhesive layers with greater thickness tend to have better step-following ability and can easily absorb deformation caused by foreign matter, etc. Impact resistance also tends to improve. The technology disclosed herein can preferably be implemented in an embodiment in which the thickness of the adhesive layer is, for example, 30 μm or more. The thickness of the adhesive layer may be 35 μm or more, 40 μm or more, 45 μm or more, 50 μm or more, 75 μm or more, or 90 μm or more. On the other hand, as the thickness of the adhesive layer increases, the optical path passing through the adhesive layer also becomes longer, making optical distortion more easily noticeable. For this reason, in some embodiments, the thickness of the adhesive layer is appropriately set to, for example, 200 μm or less, but may also be 150 μm or less, 120 μm or less, preferably 100 μm or less, more preferably 70 μm or less, even more preferably 50 μm or less, and may also be 35 μm or less. An adhesive layer having such a thickness can better suppress the deformation of the adhesive layer. According to the technology disclosed herein, a bond with high deformation resistance and high impact resistance can be formed with an adhesive layer having a thickness of, for example, 70 μm or less.

[0173] The thickness of the adhesive layer can be measured using a 1 / 1000 mm scale dial gauge with a flat measuring probe. For example, in the case of a release film / adhesive layer / release film configuration, the total thickness can be measured using a 1 / 1000 mm scale dial gauge with a flat measuring probe, and the thickness of the release film can be subtracted to calculate the total thickness.

[0174] (Peak top temperature of tanδ) The adhesive constituting the adhesive layer disclosed herein preferably has a peak top temperature of its loss tangent tanδ in the range of -50°C to 0°C. Adhesives with a tanδ peak top in the low-temperature region tend to provide good impact resistance. The peak top temperature of the loss tangent tanδ of the adhesive can be determined by the following method. That is, dynamic viscoelasticity measurements are performed under the same conditions as the measurement of the storage modulus at 25°C described below, and the storage modulus G' and loss modulus G'' are measured. Then, the loss tangent tanδ is calculated using the following equation: tanδ = G'' / G'; and by plotting its temperature dependence, the temperature corresponding to its peak top (the temperature at which the tanδ curve is maximum) can be determined.

[0175] (Storage modulus at 25°C) The storage modulus of the adhesive layer at 25°C (25°C storage modulus) is appropriately set according to the intended use and manner of use, and is not limited to a specific range. From the viewpoint of adhesive properties such as deformation resistance and heat resistance, the above 25°C storage modulus is approximately 4 × 10⁻⁶. 4 It is appropriate to set it to Pa or higher, preferably about 6 × 10 4 Pa or higher, more preferably approximately 8 × 10 4 It is above Pa, approximately 1.0 × 10⁻⁶ 5 It may be Pa or higher, approximately 1.2 × 10 5 Pa or higher is also acceptable, approximately 1.5 × 10 5 A value of Pa or higher is sufficient, approximately 1.8 × 10 5 It may be Pa or higher. The adhesive layer with a high storage modulus at 25°C tends to have excellent resistance to compressive deformation. Also, the storage modulus at 25°C can be, for example, 1 × 10⁻⁶. 7 It is less than Pa, approximately 1 × 10⁻⁶ 6 A value of Pa or less is appropriate. From the viewpoint of suitably exhibiting adhesive properties such as adhesion, the above 25°C storage modulus is preferably approximately 5.0 × 10⁻⁶. 5 Pa or less, more preferably approximately 3.0 × 10 5 Pa or less, more preferably about 2.0 × 10 5 It is less than Pa, approximately 1.4 × 10 5 It may be less than or equal to Pa, approximately 1.0 × 10 5It may be less than Pa. The storage modulus at 25°C of the adhesive sheet (typically a substrate-less adhesive sheet) is also preferably within the range exemplified above. The 25°C storage modulus can be adjusted by the molecular weight, molecular structure, concentration, degree of crosslinking, etc. of the base polymer. The 25°C storage modulus is measured by the following method. The same applies to the examples described later.

[0176] [Storage modulus at 25°C] An adhesive layer approximately 2 mm thick is prepared by stacking multiple adhesive sheets or adhesive layers to be measured. A sample of this adhesive layer, punched out into a 7.9 mm diameter disc, is sandwiched and fixed between parallel plates, and dynamic viscoelasticity measurements are performed using a viscoelasticity tester (e.g., ARES or equivalent manufactured by T.A. Instruments) under the following conditions to determine the storage modulus G'(25°C)[Pa] at 25°C. • Measurement mode: Shear mode Temperature range: -70℃ to 150℃ • Heating rate: 5°C / min ·Measurement frequency: 1Hz

[0177] (Gel fraction) The gel fraction of the adhesive layer is appropriately set according to the purpose and manner of use, and is not limited to a specific range. The gel fraction is, for example, approximately 99% by weight or less, and approximately 97% by weight or less is appropriate. From the viewpoint of step-following ability, in some preferred embodiments, the gel fraction is approximately 95% by weight or less, more preferably approximately 92% by weight or less, and may also be approximately 88% by weight or less, approximately 75% by weight or less, or approximately 65% ​​by weight or less. An adhesive layer having the above gel fraction can, for example, follow the irregularities of a print such as a logo mark formed on the surface of the adherend without impairing visibility. Furthermore, from the viewpoint of exhibiting good adhesive properties and viscoelastic properties, the gel fraction of the adhesive layer is, for example, approximately 10% by weight or more, and it is appropriate to set it to approximately 20% by weight or more. From the viewpoint of deformation resistance, etc., the gel fraction is preferably approximately 30% by weight or more, more preferably approximately 40% by weight, and may be approximately 50% by weight or more, approximately 65% ​​by weight or more, or approximately 75% by weight or more. It is also preferable that the gel fraction of the adhesive sheet (typically a substrate-less adhesive sheet) be within the range exemplified above. The gel fraction can be adjusted by the molecular weight, molecular structure, concentration, degree of crosslinking, etc. of the base polymer. The gel fraction is measured by the following method. The same applies to the examples described later.

[0178] [Gel fraction] A predetermined amount of adhesive sample (weight Wg1) is wrapped in a drawstring-like shape with a porous polytetrafluoroethylene membrane (weight Wg2) having an average pore size of 0.2 μm, and the opening is tied with string (weight Wg3). As the porous polytetrafluoroethylene (PTFE) membrane, the product name "Nitoflon (registered trademark) NTF1122" (average pore size 0.2 μm, porosity 75%, thickness 85 μm) or an equivalent product available from Nitto Denko Corporation is used. The package is immersed in a sufficient amount of ethyl acetate and kept at room temperature (typically 23°C) for 7 days to elute only the sol component in the adhesive layer from the film. Then the package is removed, the ethyl acetate adhering to the outer surface is wiped off, and the package is dried at 130°C for 2 hours. The weight of the package (Wg4) is then measured. The gel fraction of the adhesive layer can be determined by substituting each value into the following formula. Gel fraction (%) = [(Wg4 - Wg2 - Wg3) / Wg1] × 100

[0179] Furthermore, the adhesive sheets disclosed herein include adhesive sheets in which the adhesive layer is photocured after being bonded to a substrate. Therefore, for at least the photocurable adhesive sheet (for example, the adhesive sheet of Example 4 having adhesive C described later), an illuminance of 300 mW / cm² is required. 2 , cumulative light intensity 3000 mJ / cm 2 The measurement samples shall be irradiated with ultraviolet light under the specified conditions and aged at 50°C for 48 hours. The following measurements shall be performed on the sample: tanδ peak top temperature, 25°C storage modulus, gel fraction, total light transmittance, haze value, maximum height Rz of the adhesive surface, arithmetic mean roughness Ra, adhesive strength, modulus of elasticity by tensile test, and impact resistance. When the release film is transparent, it is preferable to perform the above ultraviolet light irradiation treatment with the adhesive sheet (typically the adhesive layer) sandwiched between transparent release films.

[0180] <Supporting base material> Adhesive sheets according to several embodiments may be in the form of an adhesive sheet with a support substrate, including a support substrate. The material of the support substrate is not particularly limited and can be appropriately selected according to the purpose and manner of use of the adhesive sheet. Non-limiting examples of support substrates that can be used include: resin films such as polyolefin films mainly composed of polyolefins such as polypropylene and ethylene-propylene copolymer, polyester films mainly composed of polyesters such as polyethylene terephthalate and polybutylene terephthalate, and polyvinyl chloride films mainly composed of polyvinyl chloride; foam sheets made of foams such as polyurethane foam, polyethylene foam, and polychloroprene foam; woven and nonwoven fabrics made by single or blended fibrous materials (which may be natural fibers such as hemp and cotton, synthetic fibers such as polyester and vinylon, and semi-synthetic fibers such as acetate); papers such as Japanese paper, fine paper, kraft paper, and crepe paper; and metal foils such as aluminum foil and copper foil. Support substrates may also be composed of a composite of these. Examples of such composite support substrates include, for example, a support substrate with a structure in which a metal layer (e.g., metal foil, continuous or discontinuous metal sputtered layer, metal vapor deposition layer, metal plating layer, etc.) or a metal oxide layer is laminated with the resin film, or a resin sheet reinforced with inorganic fibers such as glass cloth. The support substrate may also correspond to an optical component (e.g., an optical film) as described later, or it may be a transparent component formed from a transparent material (e.g., a transparent resin material or glass, etc.).

[0181] Various films (hereinafter also referred to as "support films") can be preferably used as the support substrate for the adhesive sheets disclosed herein. The support film may be a porous film such as a foam film or a nonwoven fabric sheet, a nonporous film, or a film with a structure in which a porous layer and a nonporous layer are laminated. In some embodiments, the support film may preferably include a resin film that is independently shape-retaining (self-supporting or independent) as a base film. Here, "resin film" means a resin film with a nonporous structure, which is typically substantially free of air bubbles (voidless). Therefore, the resin film is a concept distinct from foam films and nonwoven fabrics. The resin film may have a single-layer structure or a multilayer structure of two or more layers (for example, a three-layer structure).

[0182] As resin materials constituting the resin film, for example, polycycloolefins derived from monomers having an aliphatic ring structure such as polyester, polyolefins, norbornene structures, polyamides (PA) such as nylon 6, nylon 66, and partially aromatic polyamides, polyimides (PI), polyamide-imides (PAI), polyetheretherketones (PEEK), polyethersulfones (PES), polyphenylene sulfide (PPS), polycarbonate (PC), polyurethane (PU), ethylene-vinyl acetate copolymers (EVA), fluororesins such as polystyrene, polyvinyl chloride, polyvinylidene chloride, and polytetrafluoroethylene (PTFE), acrylic resins such as polymethyl methacrylate, cellulosic polymers such as diacetylcellulose and triacetylcellulose, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers, and epoxy polymers can be used. The above resin film may be formed using a resin material containing one of these resins alone, or it may be formed using a resin material blended with two or more of these resins. The above resin film may be unstretched or stretched (for example, uniaxially stretched or biaxially stretched).

[0183] Suitable examples of resin materials constituting resin films include polyester resins, PPS resins, and polyolefin resins. Here, a polyester resin refers to a resin containing polyester in a proportion of more than 50% by weight. Similarly, a PPS resin refers to a resin containing PPS in a proportion of more than 50% by weight, and a polyolefin resin refers to a resin containing polyolefin in a proportion of more than 50% by weight.

[0184] Typically, polyester resins are used that primarily contain polyester obtained by polycondensation of dicarboxylic acid and diol. Specific examples of polyester resins include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polybutylene naphthalate.

[0185] Polyolefin resins can be made using one type of polyolefin alone or in combination of two or more types of polyolefins. These polyolefins may include, for example, α-olefin homopolymers, copolymers of two or more α-olefins, or copolymers of one or more α-olefins with other vinyl monomers. Specific examples include polyethylene (PE), polypropylene (PP), poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene rubber (EPR), ethylene-propylene-butene copolymers, ethylene-butene copolymers, ethylene-vinyl alcohol copolymers, and ethylene-ethyl acrylate copolymers. Both low-density (LD) and high-density (HD) polyolefins are usable. Examples of polyolefin resin films include unoriented polypropylene (CPP) film, biaxially oriented polypropylene (OPP) film, low-density polyethylene (LDPE) film, linear low-density polyethylene (LLDPE) film, medium-density polyethylene (MDPE) film, high-density polyethylene (HDPE) film, polyethylene (PE) film made by blending two or more types of polyethylene (PE), and PP / PE blend film made by blending polypropylene (PP) and polyethylene (PE).

[0186] Specific examples of resin films that can be preferably used as a support substrate include PET film, PEN film, PPS film, PEEK film, CPP film, and OPP film. From the viewpoint of strength, PET film, PEN film, PPS film, and PEEK film are preferred examples. From the viewpoint of availability, dimensional stability, optical properties, etc., PET film is a preferred example.

[0187] The resin film may contain known additives such as light stabilizers, antioxidants, antistatic agents, colorants (dyes, pigments, etc.), fillers, slip agents, and antiblocking agents, as needed. The amount of additives is not particularly limited and can be set appropriately depending on the application of the adhesive sheet.

[0188] The method for manufacturing the resin film is not particularly limited. For example, conventionally known general resin film molding methods such as extrusion molding, inflation molding, T-die casting, and calender roll molding can be used as appropriate.

[0189] The above-mentioned support substrate may be a support film substantially composed of such a resin film. Furthermore, the above-mentioned support substrate may be a support film including an auxiliary layer in addition to the resin film. The auxiliary layer may be located on the adhesive layer side of the resin film, on the opposite side of the adhesive layer, or on both sides of the resin film. Examples of the auxiliary layer include optical property adjustment layers (e.g., coloring layers, anti-reflective layers), decorative layers that impart a desired appearance to the support substrate or adhesive sheet (e.g., printing layers, laminating layers, continuous or discontinuous metal layers, continuous or discontinuous metal oxide layers, etc.), conductive layers, antistatic layers, primer layers, release layers, and the like.

[0190] In some embodiments, the support substrate is preferably a transparent plastic film. In this embodiment, the total light transmittance of the support substrate is, for example, approximately 50% or more, and preferably approximately 70% or more. From the viewpoint of visibility of the adherend through the adhesive sheet, in some preferred embodiments, the total light transmittance of the support substrate is approximately 85% or more, and more preferably approximately 90% or more. The upper limit of the above total light transmittance may practically be approximately 95% or less, and may also be approximately 94% or less (for example, 93% or less). The total light transmittance of the support substrate can be measured using a haze meter. For the haze meter, the "HM-150N" model manufactured by Murakami Color Technology Laboratory, or an equivalent model, can be used.

[0191] The thickness of the support substrate is not particularly limited and can be selected according to the purpose and manner of use of the adhesive sheet. The thickness of the support substrate may be, for example, 1000 μm or less, and from the viewpoint of handling (e.g., ease of winding), it is appropriate to be 500 μm or less, preferably 300 μm or less, and may also be 100 μm or less, 70 μm or less, 50 μm or less, 25 μm or less, 10 μm or less, or 5 μm or less. As the thickness of the support substrate decreases, the flexibility of the adhesive sheet and its ability to conform to the surface shape of the adherend tend to improve. Also, from the viewpoint of handling and processability, the thickness of the support substrate may be, for example, 2 μm or more, and may be greater than 5 μm or greater than 10 μm. In some embodiments, the thickness of the support substrate may be, for example, 20 μm or more, 35 μm or more, or 55 μm or more.

[0192] The surface of the support substrate that is joined to the adhesive layer may be subjected to conventionally known surface treatments as needed, such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, application of a primer, or antistatic treatment. Such surface treatments may be intended to improve the adhesion between the support substrate and the adhesive layer, in other words, the anchoring ability of the adhesive layer to the support substrate. The composition of the primer is not particularly limited and can be appropriately selected from known primers. The thickness of the undercoat layer is not particularly limited, but approximately 0.01 μm to 1 μm is appropriate, and approximately 0.1 μm to 1 μm is preferred.

[0193] <Method for manufacturing adhesive sheets with release film> The method for manufacturing the adhesive sheet with release film disclosed herein is not particularly limited. For example, an adhesive sheet with release film can be obtained by applying an adhesive composition to the release surface of a release film and drying (e.g., heat drying) or curing it to form an adhesive layer on the release surface, and then laminating a different release film onto the surface of this adhesive layer opposite to the release surface. Alternatively, an adhesive sheet with release film can be formed by drying or curing an adhesive composition sandwiched between two release films to form an adhesive layer. In the case of an adhesive sheet having a support substrate, for example, a method can be employed in which an adhesive layer is formed by applying an adhesive composition to the support substrate and drying or curing it (direct method). Alternatively, a method can be employed in which an adhesive layer is formed on a surface that has release properties (release surface) by applying an adhesive composition and drying it, and then transferring the adhesive layer to the support substrate (transfer method).

[0194] The curing treatment may include crosslinking (for example, crosslinking by the reaction of the crosslinking agent described above), cooling, etc. When two or more curing treatments are performed, they can be carried out simultaneously or in stages. Various conventionally known methods can be used as the application method for the adhesive composition. Specifically, examples include roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and extrusion coating methods using die coaters, etc.

[0195] The adhesive sheet with a release film disclosed herein can be suitably manufactured by a method comprising drying or curing a liquid film of an adhesive composition on the release surface of the release film to form an adhesive layer. According to this method, the smoothness of the surface of the adhesive layer formed in contact with the release surface can be precisely controlled by drying or curing the fluid adhesive composition (liquid film) in contact with the release surface. The release surface typically has a maximum height (Rz) limited to a predetermined value or less, and by using a release film with such a release surface, a highly smooth adhesive surface can be manufactured stably (with good reproducibility).

[0196] The adhesive sheet with release film disclosed herein can preferably be manufactured by a method that includes curing a liquid film of the adhesive composition between the release surfaces of a first release film and a second release film to form an adhesive layer. As a method for arranging the liquid film of the adhesive composition between the release surfaces of the first release film and the second release film, one method can be employed in which a liquid adhesive composition is applied to the release surface of one release film, and then the other release film is placed over the liquid film of the adhesive composition. Another method is to supply the first release film and the second release film between a pair of rolls so that their release surfaces face each other, and to supply a liquid adhesive composition between their release surfaces. It is preferable to apply the adhesive composition at 80°C or below, and more preferably at 60°C or below (for example, 40°C or below). This suppresses roughness of the adhesive layer due to the difference in thermal expansion coefficients between the first release film, the second release film and the adhesive layer, and a smoother adhesive surface can be formed.

[0197] The total thickness of the adhesive sheet with release film disclosed herein is not particularly limited and may be, for example, about 30 μm to 1500 μm. Here, the total thickness of the adhesive sheet with release film refers to the total thickness of the adhesive sheet with release film, which consists of at least one release film (including a first release film and a second release film) and an adhesive sheet. In some embodiments, the total thickness of the adhesive sheet with release film may be, for example, 60 μm or more, 80 μm or more, 105 μm or more, 125 μm or more, or 140 μm or more. The total thickness of the adhesive sheet with release film may be, for example, 1000 μm or less, 500 μm or less, or 300 μm or less.

[0198] <Rolled form> This specification provides a roll containing an adhesive sheet with a release film as disclosed herein, wound in a manner. Such a roll typically includes a core and an adhesive sheet with a release film wound around the core. The shape of the core is not particularly limited and may be, for example, a solid cylinder, a hollow cylinder (i.e., cylindrical), a hollow or solid polygonal prism, etc. From the viewpoint of improving the handling of the roll, a hollow cylindrical or hollow polygonal prism core may be preferably used. A cylindrical core is particularly preferred.

[0199] <Attaching to the substrate> The method of attaching the adhesive sheet disclosed herein to an adherend is not particularly limited. Known or conventional pressing methods can be adopted according to the intended use and manner of use. In some preferred embodiments, the adhesive sheet may be used in a manner in which the adhesive sheet is attached to the adherend by a method that includes photocuring the adhesive layer after it has been attached to the adherend. By attaching the adhesive sheet to the adherend, an adherend in which the adhesive sheet is laminated is formed. By photocuring the adhesive layer of this adhesive sheet, a laminate is obtained in which the adhesive sheet with the cured adhesive layer and the adherend are obtained. Accordingly, this specification provides a method for attaching an adhesive sheet, comprising attaching one of the adhesive sheets disclosed herein to an adherend and photocuring the adhesive layer of the adhesive sheet by irradiating it with ultraviolet light, in this order.

[0200] <Application> The adhesive sheets disclosed herein can be used for applications such as fixing, joining, molding, decorating, protecting, and supporting components of various products. The material constituting at least the surface of the component may be, for example, glass such as alkali glass or alkali-free glass; metal materials such as stainless steel (SUS) or aluminum; resin materials such as acrylic resin, ABS resin, polycarbonate resin, polyimide resin, polyester resin such as PET, or polystyrene resin. The component may be, for example, a component of various portable devices, automobiles, home appliances, etc. Furthermore, the surface to which the adhesive sheet is attached may be a painted surface with paints such as acrylic, polyester, alkyd, melamine, urethane, acid epoxy crosslinked, or composites thereof (e.g., acrylic melamine, alkyd melamine), or a plated surface such as galvanized steel sheet. Furthermore, the component may be, for example, a resin film, or a resin film having a continuous or discontinuous inorganic layer (which may be a metal layer, a metal oxide layer, etc.).

[0201] One example of a preferred application is an optical application. More specifically, the adhesive sheet disclosed herein can be preferably used as an optical adhesive sheet for applications such as bonding optical components together (for bonding optical components) or for manufacturing products using the optical components (optical products).

[0202] The above-mentioned optical components refer to components that have optical properties (e.g., polarizing properties, light refraction properties, light diffraction properties, optical rotation properties, etc.). The above-mentioned optical components are not particularly limited as long as they have optical properties, but examples include components that make up devices (optical devices) such as display devices (image display devices) and input devices, or components used in such devices. Examples include polarizing plates, wave plates, phase difference plates, optical compensation films, brightness enhancement films, light guide plates, reflective films, anti-reflective films, hard coat (HC) films, shock-absorbing films, anti-fouling films, photochromic films, light-adjusting films, transparent conductive films (ITO films), and even components in which these are laminated (these may be collectively referred to as "functional films"). The above-mentioned "plates" and "films" include forms such as plate-like, film-like, and sheet-like, respectively, and for example, "polarizing film" includes "polarizing plates," "polarizing sheets," etc.

[0203] Examples of the above-mentioned display devices include liquid crystal displays, organic electroluminescent (EL) displays, PDPs (plasma display panels), and electronic paper. Examples of the above-mentioned input devices include touch panels.

[0204] The optical components mentioned above are not particularly limited, but examples include components made of glass, acrylic resin, polycarbonate, transparent polyimide, PET, etc. (for example, sheet-like, film-like, or plate-like components).

[0205] The manner in which optical members are bonded using the adhesive sheet disclosed herein is not particularly limited, but may include, for example, (1) bonding optical members to each other via the adhesive sheet disclosed herein, (2) bonding an optical member to a member other than an optical member via the adhesive sheet disclosed herein, or (3) a form in which the adhesive sheet disclosed herein includes an optical member and the adhesive sheet is bonded to an optical member or a member other than an optical member. In the embodiment of (3) above, the adhesive sheet that includes an optical member may be, for example, an adhesive sheet in which the support substrate is an optical member (e.g., an optical film). Such an adhesive sheet that includes an optical member as a support substrate can also be understood as an adhesive-type optical member (e.g., an adhesive-type optical film). Furthermore, if the adhesive sheet disclosed herein is an adhesive sheet of the type having a support substrate, and the functional film is used as the support substrate, the adhesive sheet disclosed herein can also be understood as an "adhesive-type functional film" having the adhesive layer disclosed herein on at least one side of the functional film.

[0206] The adhesive sheets disclosed herein can be preferably used for applications in which they are attached to decorative films. Here, a decorative film refers to a film having a design (including colors, tones, patterns, and even textual information such as logos; the same applies hereinafter) on its surface (decorative surface), and is also called a design film or decorative film. The above decorative film includes components that perform decorative and protective roles while maintaining the visibility of image display devices and input devices. Examples of decorative films include films having a decorative layer that gives a desired appearance (printed layer, laminate layer, colored layer, glossy layer, continuous or discontinuous inorganic layer (metal layer, metal oxide layer, etc.)). The above decorative film may exhibit good opacity while having a design on its surface.

[0207] The decorative film described above may have a decorative layer. Examples of the decorative layer include, for example, a printed layer, a laminate layer, a colored layer, a glossy layer, and a continuous or discontinuous inorganic layer that provides a desired appearance. Examples of continuous or discontinuous inorganic layers include a continuous or discontinuous metal layer, a continuous or discontinuous metal oxide layer, a laminate of a continuous or discontinuous metal layer and a metal oxide layer, and a continuous or discontinuous metal / metal oxide composite layer. Examples of the metal include aluminum, zinc, lead, copper, silver, and their alloys. Examples of the metal oxide include chromium oxide, indium oxide, zinc oxide, and titanium oxide. The metal layer and metal oxide layer can be formed by vapor deposition, sputtering, etc. A typical example of a decorative film is a metallic-looking film. A metallic-looking decorative film may have electromagnetic wave transmission properties in addition to metallic luster. Examples of such decorative films include electromagnetic wave-transmitting metallic glossy members as described in Japanese Patent Publication No. 2018-69462, Japanese Patent Publication No. 2019-123238, and Japanese Patent Publication No. 2019-188805.

[0208] Furthermore, the decorative film may specifically have a base layer, comprising a base layer and a decorative layer covering at least a portion of at least one surface of the base layer. Various resin films such as the plastic film mentioned above can be used as the base layer. Among these, resin films formed from polyester resins such as PET, polyolefin resins, polycarbonate resins, and (meth)acrylic resins are preferred. The thickness of the base layer is not particularly limited, and is, for example, about 5 to 250 μm. The decorative layer may be arranged on the adhesive sheet side of the base layer, on the opposite side from the adhesive sheet side, or on both sides of the base layer.

[0209] In a decorative film including a decorative layer, the thickness of the decorative layer is preferably in the range of approximately 1 to 1000 nm, for example, it may be about 1 to 300 nm or about 1 to 200 nm. Furthermore, the sheet resistance of the decorative layer is preferably 100 Ω / □ or more, for example, it may be 250 Ω / □ or more or 1000 Ω / □ or more. A decorative film having such a decorative layer can be radio wave transparent, and can therefore be preferably used in various applications where radio wave transparency is required, such as portable electronic devices. The upper limit of the sheet resistance of the decorative layer is not particularly limited, for example, 1 × 10 16 It may be less than or equal to Ω / □. The above sheet resistance can be measured based on the overcurrent measurement method described in JIS Z 2316.

[0210] The design-forming surface of the decorative film described above may have a flat plane, or it may have irregularities such as printed logos or engravings. The adhesive sheet disclosed herein may have excellent conformability to uneven surfaces, and can therefore adhere well to the surface of the decorative film having the irregularities.

[0211] Furthermore, the adhesive sheet disclosed herein can be preferably used for applications where it is attached to a transparent member or for fixing two members, at least one of which is a transparent member, because it can be used to obtain excellent visibility of the adherend based on its high surface smoothness. Examples of such member fixing applications include a configuration in which one member is a transparent member and the other member has an image display surface, a decorative surface, or a colored surface. In other words, the adhesive sheet disclosed herein is preferably used to fix a member having an image display surface, a decorative surface, or a colored surface to a transparent member. Examples of image display surfaces include the liquid crystal display surface, organic EL display surface, PDP, electronic paper, etc. Examples of decorative surfaces include the decorative surface of the decorative film. Examples of colored surfaces include the surface of a light-shielding film or an opaque film. Examples of transparent members include glass, acrylic resin, polycarbonate, PET, and other transparent materials. In such a configuration, for example, by using an adhesive sheet with a total light transmittance and haze value of a predetermined value or higher, the image display surface, decorative surface, or colored surface of the adherend can be clearly seen through the adhesive sheet and the transparent member.

[0212] The transparent member described above may be a flat plate, but it may also have irregularities such as printing or engraving on the adhesive sheet application surface, or the transparent member as a whole may have a three-dimensional shape. The adhesive sheet disclosed herein may have excellent step-following properties and can therefore adhere well to the surface of the transparent member having the irregularities. Furthermore, the transparent member having a three-dimensional shape may have a bent portion that bends in a straight line or a curved portion that curves in a curved shape in its cross-section in the thickness direction. The transparent member may have an adhesive sheet application surface that is bent or curved in any one direction, or it may have an adhesive sheet application surface that is bent or curved in two directions, in addition to the one direction mentioned above, in a direction that intersects (for example, perpendicular to) that one direction. In other words, the adhesive sheet application surface of the transparent member may have a two-dimensional or three-dimensional structure.

[0213] The adhesive sheet disclosed herein can be preferably used in portable electronic devices. In such portable electronic devices, it can be preferably used for applications where it is attached to a transparent member, or for applications where at least one of the members is a transparent member. Furthermore, in such portable electronic devices, it can be preferably used for applications where it is attached to an image display surface, a decorative surface, or a colored surface. For example, the adhesive sheet disclosed herein can be preferably used to fix an image display surface, a decorative surface, or a colored surface of a component (e.g., a decorative film) to the inside of a transparent housing, which is a transparent member. With such a configuration, the decorative surface, etc., can be seen from the outside of the housing, while, for example, in the case where a member having a colored surface is used, internal concealment can be achieved, making it particularly suitable as an exterior structure such as a case.

[0214] Non-limiting examples of the above-mentioned portable electronic devices include mobile phones, smartphones, tablet computers, notebook computers, various wearable devices (e.g., wristwear-type devices worn on the wrist like watches, modular devices attached to a part of the body with clips or straps, eyewear-type devices including glasses (monocular and binocular, including head-mounted types), clothing-type devices attached to shirts, socks, hats, etc. as accessories, earwear-type devices attached to the ears like earphones, etc.), digital cameras, digital video cameras, audio equipment (portable music players, IC recorders, etc.), calculators (calculators, etc.), portable game consoles, electronic dictionaries, electronic organizers, e-books, in-car information systems, portable radios, portable televisions, portable printers, portable scanners, portable modems, etc. In this specification, "portable" means not merely being able to carry, but having a level of portability that allows an individual (a typical adult) to carry it relatively easily.

[0215] The matters disclosed in this specification include the following: [1] comprising an adhesive sheet having an adhesive layer and a release film laminated on the adhesive surface of the adhesive sheet, An adhesive sheet with a release film, wherein the maximum height Rz of the adhesive side surface of the release film is 400 nm or less. [2] The adhesive sheet with release film according to [1], wherein the arithmetic mean roughness Ra of the adhesive side surface of the release film is 30 nm or less. [3] The adhesive sheet with a release film according to [1] or [2] above, wherein the release force of the release film on the adhesive sheet is 1 N / 50 mm or less. [4] The adhesive sheet with release film according to any one of [1] to [3] above, wherein the thickness of the release film is in the range of 50 to 125 μm. [5] The adhesive sheet with a release film according to any one of [1] to [4] above, wherein the total light transmittance of the adhesive sheet is 85% or more and the haze value is 1% or less. [6] The adhesive sheet with a release film according to any one of [1] to [5] above, wherein the adhesive sheet is a single-sided adhesive sheet having an adhesive layer and a support substrate laminated on one side of the adhesive layer. [7] The adhesive sheet is a double-sided adhesive sheet having a first adhesive surface and a second adhesive surface, The release film comprises a first release film disposed on the first adhesive surface and a second release film disposed on the second adhesive surface. The adhesive sheet with a release film according to any one of [1] to [5] above, wherein the maximum height Rz1 of the first adhesive surface S1 of the first release film and the maximum height Rz2 of the second adhesive surface S2 of the second release film are both 400 nm or less. [8] The adhesive sheet is a double-sided adhesive sheet having a first adhesive surface and a second adhesive surface, The release film is a double-sided release film having a first release surface and a second release surface. The adhesive sheet with a release film according to any one of [1] to [5] above, wherein the maximum height Rz1 of the first release surface of the release film and the maximum height Rz2 of the second release surface of the release film are both 400 nm or less. [9] The adhesive sheet with a release film according to any one of [1] to [8] above, wherein the adhesive layer is an acrylic adhesive layer.

[10] The adhesive sheet with a release film according to any one of [1] to [9] above, wherein the gel fraction of the adhesive layer is 30 to 95% by weight.

[11] The storage modulus of the adhesive sheet at 25°C is 4 × 10 4 An adhesive sheet with a release film as described in any of the above [1] to

[10] , having a Pa of 10 or higher.

[12] The adhesive sheet with a release film according to any one of [1] to

[11] above, wherein the thickness of the adhesive sheet is 5 to 100 μm.

[13] The adhesive sheet is an adhesive sheet with a release film as described in any of [1] to

[12] above, wherein the elastic modulus measured by the tensile test described below is 3.0 MPa or more. [Tensile test] The adhesive layer of the aforementioned adhesive sheet is exposed to an illuminance of 300 mW / cm². 2 , cumulative light intensity 3000 mJ / cm 2 The adhesive layer is irradiated with ultraviolet light under the specified conditions and aged at 50°C for 48 hours. After this, the adhesive layer is cut to a size of 10 mm in width and 150 mm in length to prepare a test specimen. In an environment of 23°C and 50% RH, a tensile test is performed on the test specimen using a tensile testing machine with a chuck distance of 120 mm and a tensile speed of 50 mm / min to obtain a stress-displacement curve, and the modulus of elasticity [MPa] is calculated from its initial slope.

[14] The adhesive sheet has an impact resistance of 2.0 J / 10 mm as measured by the following shear impact test. 2 The above is an adhesive sheet with a release film as described in any of [1] to

[13] above. [Shear impact test] A shear impact test will be performed using a pendulum-type adhesive shear impact tester based on JIS K6855. For the measurement sample, the first side of the 10 mm square adhesive sheet will be attached to the center of a 25 mm square, 1.7 mm thick chemically strengthened glass plate, and then the second side of the adhesive sheet will be attached to the center of a 40 mm square stainless steel plate (SUS304BA plate). The samples will be pressed together with a load of 5 N for 10 seconds, followed by autoclaving (50°C, 0.5 MPa, 15 minutes), and an illuminance of 300 mW / cm² will be applied from the glass plate side. 2 , cumulative light intensity 3000 mJ / cm 2After irradiating with ultraviolet rays under the conditions of , use the one that has been aged at 50 °C for 48 hours. Fix the measurement sample so that the stainless steel plate is on the lower side, and measure the absorption energy [J] when hitting the hammer on the outer peripheral side surface of the glass plate under the conditions of a hammer energy of 2.75 J and a hammer speed of 3.5 m / s in an environment of 23 °C and 50% RH, thereby obtaining the impact resistance [J / 10 mm 2 . 〔15〕 The adhesive layer of the adhesive sheet contains a polymer (A) and a photoreactive monomer (B), and is the adhesive sheet with a release film according to any one of the above 〔1〕~〔14〕. 〔16〕 The photoreactive monomer (B) includes a compound B1 having a ring structure and two or more ethylenically unsaturated groups in the molecule, and the molecular weight per ethylenically unsaturated group of the compound B1 is 100 g / mol or more. The adhesive sheet with a release film according to 〔15〕 above.

[0216] 〔17〕 The above compound B1 contains at least one structure selected from the group consisting of a bisphenol A structure, a bisphenol F structure, and a bisphenol E structure in the molecule. The adhesive sheet with a release film according to 〔16〕 above. 〔18〕 The above compound B1 contains an aliphatic ring structure as the above ring structure. The adhesive sheet with a release film according to 〔16〕 or 〔17〕 above. 〔19〕 The above compound B1 contains at least one structure selected from the group consisting of a hydroxyl group and an amino group in the molecule. The adhesive sheet with a release film according to any one of 〔16〕~〔18〕 above. 〔20〕 The content of the above compound B1 in the above adhesive layer is 0.5 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight of the above polymer (A). The adhesive sheet with a release film according to any one of 〔16〕~〔19〕 above. 〔21〕 The above adhesive layer contains, as the above photoreactive monomer (B), the above compound B1 and a compound B2 having 2 or more functional groups and no ring structure in the molecule. The adhesive sheet with a release film according to any one of 〔16〕~〔20〕 above.

[22] The adhesive sheet with a release film as described in

[21] , wherein the functional group equivalent of compound B2 is smaller than the functional group equivalent of compound B1.

[23] The adhesive sheet with a release film according to

[21] or

[22] above, wherein the functional group equivalent of compound B2 is 400 g / mol or less.

[24] The adhesive sheet with a release film according to any one of

[21] to

[23] , wherein the content of compound B2 in the adhesive layer is 25 parts by weight or less per 100 parts by weight of polymer (A).

[25] The adhesive sheet with a release film according to any one of

[15] to

[24] , wherein the content of the photoreactive monomer (B) in the adhesive layer is 1 part by weight or more and 80 parts by weight or less per 100 parts by weight of the polymer (A).

[26] The adhesive sheet with a release film according to any one of

[15] to

[25] above, wherein the polymer (A) is an acrylic polymer.

[27] The acrylic polymer comprising monomer components includes a monomer having a nitrogen atom-containing ring, as described in

[26] above, an adhesive sheet with a release film.

[28] An adhesive sheet with a release film according to any of

[15] to

[27] above, wherein the glass transition temperature of the polymer (A) is -45°C or higher and less than 0°C.

[29] The adhesive layer is crosslinked with a crosslinking agent, and the adhesive sheet with a release film is as described in any of

[15] to

[28] above.

[30] The adhesive layer contains a photopolymerization initiator, and the adhesive sheet with a release film is as described in any of

[15] to

[29] above.

[31] The adhesive layer contains a silane coupling agent, and the adhesive sheet with a release film is as described in any of

[15] to

[30] above.

[32] The adhesive sheet is an adhesive sheet with a release film as described in any of [1] to

[31] above, wherein the adhesive strength to glass is 1.0 N / 20 mm or more.

[0217]

[33] An adhesive sheet with a release film as described in any of [1] to

[32] above, used to fix a transparent member to a member having an image display surface, a decorative surface, or a colored surface.

[34] A roll of adhesive sheets with a release film, in which an adhesive sheet with a release film as described in any of [1] to

[33] above is wound.

[0218] The following describes several embodiments of the present invention, but it is not intended to limit the present invention to those shown in the embodiments. In the following description, "parts" and "%" are based on weight unless otherwise specified.

[0219] <Evaluation Method> [Total light transmittance and haze value] One release film is peeled off from an adhesive sheet with a release film attached, and it is bonded to a glass slide (manufactured by Matsunami Glass Industry Co., Ltd., product name "White Polishing No. 1", thickness 0.8-1.0 mm, total light transmittance 92%, haze value 0.2%). Next, the other release film is peeled off to prepare a test specimen with an adhesive sheet / glass slide layer structure. The total light transmittance and haze value of the test specimen obtained in this way are measured using a haze meter (device name "HM-150N", manufactured by Murakami Color Technology Research Institute). The above measurement is preferably performed with the glass plate to which the adhesive sheet is attached facing the light source.

[0220] [Adhesion to glass] A release-back adhesive sheet is cut to a length of 100 mm and a width of 20 mm. Next, one side of the release-back adhesive sheet is peeled off and a PET film (product name "Lumirror S-10", manufactured by Toray Industries, Inc., 25 μm thick) is backed onto it. Then, the release-back film on the other side (measurement surface side) is peeled off and pressed onto a glass plate (product name "Soda-Lime Glass #0050", manufactured by Matsunami Glass Industry Co., Ltd.) using a 2 kg roller, passing it back and forth once to create a test specimen consisting of the test plate, adhesive sheet, and PET film. The obtained test specimen is autoclaved (50°C, 0.5 MPa, 15 minutes), and then allowed to cool for 30 minutes in an atmosphere of 23°C and 50% RH. After cooling, a tensile testing machine (device name "Autograph AG-IS", manufactured by Shimadzu Corporation) is used to measure the peel strength when peeling the adhesive sheet (measurement side) from the test plate in accordance with JIS Z 0237, under conditions of 23°C, 50% RH atmosphere, tensile speed of 300 mm / min, and peel angle of 180°. This is defined as the adhesion strength to glass [N / 20mm]. Furthermore, in the case of adhesive sheets protected by a release film with release surfaces on both sides, or single-sided adhesive sheets, peeling off one side of the release film and backing with a PET film are not necessary.

[0221] [Release strength of release film] A release-back adhesive sheet is cut to a length of 150 mm and a width of 50 mm. This is fixed to a test plate, and a tensile testing machine (device name "Autograph AG-IS", manufactured by Shimadzu Corporation) is used to peel the release film from the adhesive sheet on the lightly peeled side under the conditions of 23°C, 50% RH atmosphere, tensile speed of 300 mm / min, and peeling angle of 180°. The maximum value in the following 50 mm section, excluding the 30 mm section from the start of peeling, is defined as the release film peeling force (lightly peeled side) [N / 50 mm]. The peeling force of the heavy-peel side release film is determined by peeling off the light-peel side release film protecting the adhesive sheet with the release film attached, backing it with a PET film (product name "Lumirror S-10", manufactured by Toray Industries, Inc., 25 μm thick), fixing the PET film side to a test plate, and using a tensile testing machine (device name "Autograph AG-IS", manufactured by Shimadzu Corporation) at 23°C, 50% RH, with a tensile speed of 300 mm / min and a peeling angle of 180°, to peel the heavy-peel side release film from the adhesive sheet. Excluding the section of 30 mm from the start of peeling, the maximum value in the following 50 mm section is defined as the release film peeling force (heavy-peel side) [N / 50 mm]. In the case of adhesive sheets protected by a release film with release surfaces on both sides, or adhesive sheets with adhesive on one side, the measurement can be performed on one of the release surfaces in the same way as the measurement of the release force of the release film on the easily release side, and a PET film backing is not necessary.

[0222] [Arithmetic mean roughness (Ra) and maximum height (Rz)] The arithmetic mean roughness (Ra) and maximum height (Rz) of the adhesive surface of the adhesive sheet are measured as follows: Under the above conditions for measuring the peeling force of the release film, the release film is peeled from the adhesive sheet with the release film attached at a peeling angle of 180° and a speed of 300 mm / min. After standing for 30 minutes, the surface shape of the exposed adhesive surface is measured using a 3D optical profiler (product name "NewView7300", manufactured by ZYGO) in an environment of 23°C and 50% RH. The arithmetic surface roughness Ra is calculated from the measured data in accordance with JIS B 0601-2001. The maximum height (Rz) is determined as the sum of the height Rp of the highest peak above the mean line of the roughness curve obtained from the above measurement and the depth Rv of the deepest valley below the mean line. The measurement conditions are as follows: Ra and Rz are measured 5 times (i.e., N=5), and their average values ​​are used. (Measurement conditions) Measurement area: 5.62mm x 4.22mm (Objective lens: 2.5x, Internal lens: 0.5x) Analysis mode: Remove: Cylinder Data Fill: ON (Max: 25) Remove Spikes: ON (xRMS:1) Filter: OFF

[0223] [Optical distortion evaluation] A commercially available mirror (2mm thick) made from plain glass using the silvering method is prepared, and it is confirmed to be distortion-free by visual inspection and by projecting a reflected image onto a screen using the same method as described below. In a clean room, after removing foreign matter from the surface of the mirror using a clean cloth, one side of the release film of the adhesive sheet with a release film is peeled off from the adhesive sheet, and the mirror is attached to the surface of the mirror with appropriate tension to prevent foreign matter, air bubbles, or deformation streaks from getting into it, and degassing is performed using a pressurized degassing device (autoclave) to remove the effects of minute air bubbles (processing conditions: 50℃, 0.5MPa, 15 minutes). After cooling at room temperature for 30 minutes or more, the other side of the release film is peeled off from the adhesive sheet to create an optical distortion evaluation sample (a laminate consisting of an adhesive sheet and a mirror). The evaluation sample is positioned with the adhesive sheet side facing the point light source, so that the angle with respect to the light ray from the point light source is approximately 45 degrees. A white screen is placed in front of the light ray and the reflected image is projected onto it. As a point light source, you can use the "Xenon Lamp C2577" manufactured by Hamamatsu Photonics, or an equivalent product. The point light source, evaluation sample, and screen should be positioned so that the distance between the evaluation sample and the point light source, and the distance between the evaluation sample and the screen, are both approximately 50 cm. By illuminating the point light source and visually observing the image projected onto the screen by reflecting the sample, the presence and degree of optical distortion are evaluated in the following three levels. E: No optical distortion is observed. A: Some optical distortion is present, but it is at a level that is practically acceptable. P: Clear optical distortion is observed.

[0224] [Module of elasticity determined by tensile testing] Prepare a test piece by cutting a pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer) with a release film into a size of 10 mm in width and 150 mm in length. In an environment of 23°C and 50% RH, peel off two release films to expose the pressure-sensitive adhesive layer, and use a tensile testing machine (device name: "Autograph AG-IS", manufactured by Shimadzu Corporation) to perform a tensile test on the above test piece under the conditions of a chuck distance of 120 mm and a tensile speed of 50 mm / min to obtain an S-S curve, and calculate the elastic modulus [MPa] from its initial slope (the elastic deformation region of the above S-S curve, specifically, the slope in the range where the displacement is less than approximately 5%).

[0225] In addition, the thickness of the test piece used in the above tensile test may be the same as or different from the thickness of the pressure-sensitive adhesive sheet (typically the pressure-sensitive adhesive layer) as described above. For example, when the thickness of the pressure-sensitive adhesive sheet is relatively small, for the purpose of improving operability, etc., the results obtained by performing the above tensile test using a test piece prepared to have a thickness of 5 μm or more (for example, about 5 μm to 200 μm) can be adopted as the elastic modulus of the above pressure-sensitive adhesive sheet. The thickness of the test piece can be adjusted, for example, for a photocurable pressure-sensitive adhesive sheet, by appropriately overlapping the pressure-sensitive adhesive layers before ultraviolet irradiation. Also, using the same pressure-sensitive adhesive composition as that used for forming the pressure-sensitive adhesive layer to be measured, a test piece with a thickness suitable for performing a tensile test is prepared, and the results obtained by performing the above tensile test on the test piece can be adopted as the elastic modulus of the pressure-sensitive adhesive layer. The above tensile test can be performed, for example, using a test piece with a thickness of about 10 μm to 50 μm (preferably about 15 μm to 25 μm).

[0226] [Impact Resistance] A shear impact test will be performed using a pendulum-type adhesive shear impact tester based on JIS K 6855. For the measurement sample, an adhesive sheet with a release film will be cut into 10 mm squares. One side of the release film will be peeled off to expose the first adhesive surface of the adhesive sheet. This first adhesive surface will be attached to the center of a 25 mm square, 1.7 mm thick chemically strengthened glass plate (manufactured by Corning). Then, the other side of the release film will be peeled off to expose the second adhesive surface of the adhesive sheet. This second adhesive surface will be attached to the center of a 40 mm square stainless steel plate (SUS304BA plate) and pressed with a load of 5 N for 10 seconds. Subsequently, autoclave treatment (50°C, 0.5 MPa, 15 minutes) will be performed, and an illuminance of 300 mW / cm² will be applied from the glass plate side using a high-pressure mercury lamp. 2 , cumulative light intensity 3000 mJ / cm 2 The product used will have been irradiated with ultraviolet light under these conditions, followed by aging at 50°C for 48 hours. The above measurement sample is fixed with the stainless steel plate facing downwards, and the absorbed energy [J] is measured when a hammer is struck against the outer surface of the glass plate under the conditions of hammer energy 2.75J and hammer speed (impact velocity) 3.5m / sec in an environment of 23℃ and 50%RH, thereby determining the impact resistance [J / 10mm]. 2 Calculate ]. Three measurements are taken, and the arithmetic mean is used. In the case of an adhesive sheet protected by a release film with peelable surfaces on both sides, the measurement can be performed in the same manner as described above, except that only one release film is peeled off.

[0227] Furthermore, the adhesive sheets disclosed herein include adhesive sheets in which the adhesive layer is photocured after being bonded to a substrate. Therefore, for at least the photocurable adhesive sheet (for example, the adhesive sheet of Example 4 having adhesive C described later), an illuminance of 300 mW / cm² is required. 2 , cumulative light intensity 3000 mJ / cm 2The above measurements (total light transmittance, haze value, adhesion to glass, arithmetic mean roughness (Ra) and maximum height (Rz) of the adhesive surface, optical distortion evaluation, and elastic modulus by tensile test) shall be performed using a measurement sample after irradiation with ultraviolet light under the specified conditions and aging at 50°C for 48 hours. For adhesion to glass, the measurement shall be performed after pressing the photocurable adhesive sheet (for example, the adhesive sheet of Example 4 having adhesive C described later) onto the test plate and irradiating it with ultraviolet light under the above conditions. Furthermore, if the release film is transparent, it is preferable to perform the above ultraviolet irradiation treatment with the adhesive sheet (typically the adhesive layer) sandwiched between transparent release films. It is preferable to measure the illuminance and light intensity of the light source by adjusting the actual distance between the light source and the sample using an industrial UV checker (model "UVR-T2", light receiving unit "UD-T36T2", manufactured by TOPCON).

[0228] <Example 1> (Preparation of adhesive composition) 57 parts of n-butyl acrylate (BA), 12 parts of cyclohexyl acrylate (CHA), 23 parts of 4-hydroxybutyl acrylate (4HBA), 8 parts of hydroxyethyl acrylate (HEA) as monomer components, and 0.075 parts of "Irgacure 651" (manufactured by BASF) and 0.075 parts of "Irgacure 184" (manufactured by BASF) as photopolymerization initiators were blended. This monomer mixture was then partially photopolymerized by exposing it to ultraviolet light under a nitrogen atmosphere to obtain a partially polymerized product (acrylic polymer syrup) with a polymerization rate of approximately 10%. 100 parts of the obtained acrylic polymer syrup were mixed uniformly with 0.14 parts of dipentaerythritol hexaacrylate (trade name "KAYARAD DPHA", manufactured by Nippon Kayaku Co., Ltd.) and 0.3 parts of a silane coupling agent (trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) to obtain acrylic adhesive composition A.

[0229] (Making adhesive sheets) As the first release film, a PET release film with a thickness of 75 μm was prepared, in which the first adhesive surface side surface S1, which is laminated on the first adhesive surface of the adhesive sheet, is a release surface treated with a silicone-based release agent, and the Ra of this surface S1 is 18 nm and the Rz is 223 nm. As the second release film, a PET release film with a thickness of 100 μm was prepared, in which the second adhesive surface side surface S2, which is laminated on the second adhesive surface of the adhesive sheet, is a release surface treated with a silicone-based release agent, and the Ra of this surface S2 is 18 nm and the Rz is 223 nm. The acrylic adhesive composition A obtained above was applied to the first adhesive side surface S1 of the first release film so that the thickness after the adhesive layer formation was 100 μm, thereby forming an adhesive composition layer. Next, the second release film was covered over the surface of the adhesive composition layer so that its second adhesive side surface S2 faced the adhesive composition layer. This shielded the adhesive composition layer from oxygen. Subsequently, the illuminance was set to 5 mW / cm². 2 , light intensity 2000mJ / cm 2 Under these conditions, ultraviolet irradiation was performed to photocur the adhesive composition layer, and a substrate-less double-sided adhesive sheet was prepared consisting only of an acrylic adhesive layer (also called adhesive A), with each side of the acrylic adhesive layer protected by first and second release films. The weight-average molecular weight (Mw) of the acrylic polymer used as the base polymer of the adhesive layer was 2 million.

[0230] <Example 2> As the first and second release films, release films having surfaces S1 and S2 with Ra and Rz as shown in Table 1 were used, respectively. In addition, the thickness of the adhesive layer was changed to 25 μm. The substrate-less double-sided adhesive sheet according to this example was prepared in the same manner as in Example 1 above.

[0231] <Example 3> An acrylic polymer syrup was prepared in the same manner as in Example 1, except that the monomer components were changed to 68 parts of 2-ethylhexyl acrylate (2EHA), 15 parts of N-vinyl-2-pyrrolidone (NVP), and 17 parts of HEA. An acrylic adhesive composition B was obtained in the same manner as in Example 1, except that the obtained acrylic polymer syrup was used. Using the obtained acrylic adhesive composition B, a substrate-less double-sided adhesive sheet according to this example was prepared in the same manner as in Example 2, except that the thickness of the adhesive layer (also called adhesive B) was set to 50 μm.

[0232] <Example 4> (Preparation of adhesive composition) In a reaction vessel equipped with a condenser, nitrogen inlet tube, thermometer, and stirrer, 60 parts BA, 6 parts CHA, 18 parts NVP, 1 part isostearyl acrylate (iSTA), and 15 parts 4HBA were added as monomer components, 0.085 parts α-thioglycerol as a chain transfer agent, 0.2 parts 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator, and ethyl acetate as the polymerization solvent until the monomer components reached 45%. Nitrogen gas was then introduced, and the mixture was purged with nitrogen for approximately 1 hour while stirring. Subsequently, the reaction vessel was heated to 60°C and reacted for 7 hours to obtain an acrylic polymer with a weight-average molecular weight (Mw) of 350,000. To this acrylic polymer solution (100 parts solids), 0.1 parts by solids of trimethylolpropane / xylylene diisocyanate adduct (manufactured by Mitsui Chemicals, trade name "Takenate D-110N", solids concentration 75%) was added as an isocyanate crosslinking agent; 0.01 parts of dioctyltin dilaurate (manufactured by Tokyo Fine Chemical Co., Ltd., trade name "Envirizer OL-1") was added as a crosslinking accelerator; 4 parts of acetylacetone was added as a crosslinking retarder; 0.3 parts of 3-glycidoxypropyltrimethoxysilane (trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a silane coupling agent; 8 parts of dipentaerythritol hexaacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., trade name "A-DPH") and 12 parts of tricyclodecanedimethanol diacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., trade name "A-DCP") were added as photoreactive monomers; and 1-hydroxycyclohexyl-phenyl-ketone (IGM) was added as a photopolymerization initiator. 0.7 parts of Regins' product, "Omnirad 184," were added and uniformly mixed to prepare adhesive composition C according to this example.

[0233] (Making adhesive sheets) As the first and second release films, release films having surfaces S1 and S2 with Ra and Rz as shown in Table 1 were used, respectively. The adhesive composition C obtained above was applied to the first adhesive side surface S1 of the first release film to a thickness of 20 μm after drying, and heated and dried at 60°C for 1 minute and 120°C for 3 minutes under normal pressure, followed by aging at 23°C for 120 hours to form a photocurable adhesive layer (substrate-less double-sided adhesive sheet). The second adhesive side surface S2 of the second release film was bonded to the surface of this photocurable adhesive layer for protection. In this way, a substrate-less double-sided adhesive sheet was produced consisting only of a photocurable acrylic adhesive layer (also called adhesive C), with each surface of the photocurable acrylic adhesive layer protected by the first and second release films.

[0234] <Example 5> As the first and second release films, release films having surfaces S1 and S2 with Ra and Rz as shown in Table 1 were used, respectively. In addition, the thickness of the adhesive layer was changed to 100 μm. The substrate-less double-sided adhesive sheet according to this example was prepared in the same manner as in Example 3 above.

[0235] <Examples 6-7> For the first and second release films, release films having surfaces S1 and S2 with Ra and Rz as shown in Table 1 were used, respectively. In Example 6, the thickness of the adhesive layer was changed to 25 μm. Otherwise, the substrate-less double-sided adhesive sheets for each example were prepared in the same manner as in Example 1 above.

[0236] <Rating> For each example, the adhesive sheet with release film was evaluated for total light transmittance [%], haze value [%], adhesion strength to glass [N / 20mm], release force of the release film [N / 50mm], arithmetic mean roughness (Ra) [nm] of the adhesive surface, maximum height (Rz) [nm], and optical distortion. The results are shown in Table 1. In addition, the elastic modulus of the adhesive sheet in Example 4 was measured by a tensile test, and impact resistance tests were performed on the adhesive sheets in Examples 1 to 4. Table 1 also shows an overview of each example (release surface Ra, Rz of the release film, adhesive type, adhesive sheet thickness [μm], storage modulus at 25°C [Pa], gel fraction [%]).

[0237] [Table 1]

[0238] As shown in Table 1, in Examples 1-5, the maximum height Rz of the adhesive side surface of the release film was 400 nm or less, and in these examples, no optical distortion was observed after peeling of the release film, or the optical distortion was within a practically acceptable range. Furthermore, the arithmetic mean roughness Ra of the adhesive side surface of the release film in these examples was 30 nm or less, and the peeling force of the release film was 1 N / 50 mm or less. On the other hand, in Examples 6-7, the maximum height Rz of the adhesive side surface of the release film exceeded 400 nm, and irregularities were observed in the optical distortion evaluation. The elastic modulus of the adhesive sheet in Example 4, as determined by tensile testing, was 3.0 MPa or higher, and the adhesive sheets in Examples 1-4 all had an impact resistance of 2.0 J / 10 mm. 2 That was all.

[0239] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. [Explanation of Symbols]

[0240] 1, 2 Adhesive sheets with release film 10 Adhesive Sheets 10a 1st adhesive side, adhesive side 10b 2nd adhesive side 12 Adhesive layer 12a 1st page 12b Side 2 14 Supporting base material 14a Adhesive layer side surface 14b Back 21. First release film, release film 21a First adhesive side surface S1 (peel surface), adhesive side surface (peel surface) 22. Second release film 22a 2nd adhesive side surface S2 (release surface) 50 cores 100, 200 rolls (adhesive sheet rolls)

Claims

1. The device comprises an adhesive sheet having an adhesive layer, and a release film laminated on the adhesive surface of the adhesive sheet, The adhesive sheet is a single-sided adhesive sheet having an adhesive layer and a support substrate laminated on one side of the adhesive layer. The total light transmittance of the adhesive sheet is 85% or more, and the haze value is 1% or less. An adhesive sheet with a release film, wherein the maximum height Rz of the adhesive side surface of the release film is 240 nm or less, and the arithmetic mean roughness Ra of the surface is 15 nm or more and less than 50 nm.

2. The adhesive sheet with release film according to claim 1, wherein the arithmetic mean roughness Ra of the surface of the release film is 15 nm or more and 30 nm or less.

3. The adhesive sheet with release film according to claim 1 or 2, wherein the peeling force of the release film on the adhesive sheet is 1 N / 50 mm or less.

4. The adhesive sheet with release film according to any one of claims 1 to 3, wherein the thickness of the release film is in the range of 50 to 125 μm.

5. The adhesive sheet with release film according to any one of claims 1 to 4, wherein the adhesive layer is an acrylic adhesive layer.

6. The adhesive sheet with release film according to any one of claims 1 to 5, wherein the gel fraction of the adhesive layer is 30 to 95% by weight.

7. The storage modulus of the adhesive layer at 25°C is 4 × 10 4 An adhesive sheet with a release film according to any one of claims 1 to 6, wherein the pressure is Pa or higher.

8. The adhesive sheet with a release film according to any one of claims 1 to 7, wherein the thickness of the adhesive sheet is 5 to 100 μm.

9. The adhesive sheet with a release film according to any one of claims 1 to 8, wherein the adhesive sheet has an elastic modulus of 3.0 MPa or more as measured by the following tensile test. [Tensile Test] The adhesive layer of the aforementioned adhesive sheet is exposed to an illuminance of 300 mW / cm². ２ , cumulative light intensity 3000 mJ / cm ２ The adhesive layer is irradiated with ultraviolet light under the specified conditions and aged at 50°C for 48 hours. After this, the adhesive layer is cut to a size of 10 mm in width and 150 mm in length to prepare a test specimen. In an environment of 23°C and 50% RH, a tensile test is performed on the test specimen using a tensile testing machine with a chuck distance of 120 mm and a tensile speed of 50 mm / min to obtain a stress-displacement curve, and the modulus of elasticity [MPa] is calculated from its initial slope.

10. The adhesive layer contains a polymer (A) and a photoreactive monomer (B), as described in any one of claims 1 to 9, for the adhesive sheet with a release film.

11. The photoreactive monomer (B) comprises a compound B1 having a ring structure and two or more ethylenically unsaturated groups in its molecule, wherein the compound B1 has a molecular weight of 100 g / mol or more per ethylenically unsaturated group, according to claim 10.

12. An adhesive sheet with a release film according to any one of claims 1 to 11, used for fixing a member having an image display surface, a decorative surface, or a colored surface to a transparent member.

13. A roll of adhesive sheet with a release film, in which an adhesive sheet with a release film according to any one of claims 1 to 12 is wound.

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