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 a pressure-sensitive adhesive sheet with a release film. [Background technology]

[0002] Generally, adhesives (also called pressure-sensitive adhesives; the same applies below) are in a soft solid (viscoelastic) state at temperatures around room temperature and have the property of easily adhering to an adherend by pressure. Taking advantage of this property, adhesives are typically in the form of adhesive sheets containing a layer of the adhesive, and are widely used in various industrial fields, from home appliances to automobiles and office automation equipment.

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

[0004] [Patent Document 1] Patent No. 4673344 [Patent Document 2] Patent No. 4805999 [Patent Document 3] JP 2017-105974 A [Patent Document 4] Patent No. 4069625 [Patent Document 5] Patent No. 6300788 Summary of the Invention [Problem to be solved by the invention]

[0005] In various products such as portable electronic devices, the pressure-sensitive adhesive sheet can be used in an area that is visible from the outside. For example, the pressure-sensitive adhesive sheet for portable electronic devices can be used not only on the image display surface of the electronic device, but also on other surfaces (e.g., the back surface). Therefore, the pressure-sensitive adhesive sheet used for this purpose may be required to have high transparency that makes its presence unnoticeable, and the adhesive surface may also be required to have high smoothness. If the adhesive surface has orange peel or streaks, the visibility through the pressure-sensitive adhesive sheet may be reduced, and the design, beauty, and luxury of the adherend surface may be impaired.

[0006] Although not particularly limited, one application in which a highly smooth adhesive surface is desirable is the application of attaching a film with a design including a specific color tone such as a metallic tone to the inside of a transparent housing constituting a portable electronic device, with the design forming surface (decoration surface) facing the transparent housing. Since both adhesive surfaces of the adhesive sheet used to fix the transparent housing and the film may affect visibility, it is desirable that both adhesive surfaces have high smoothness. Even adhesive sheets with smoothness that have been considered to be at an acceptable level in the past do not necessarily have a satisfactory level of surface smoothness, as optical distortion is observed under more accurate evaluation conditions. If an adhesive sheet with an adhesive surface with higher smoothness can be realized, it would be practically useful as a bonding means that does not impair the design, aesthetics, or luxury of the adherend.

[0007] The present invention has been made in view of the above circumstances, and has an object to provide a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive surface with high surface smoothness, protected by a release film. [Means for solving the problem]

[0008] According to this specification, a pressure-sensitive adhesive sheet with a release film is provided. This pressure-sensitive adhesive sheet with a release film includes a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer and a release film laminated on the adhesive surface of the pressure-sensitive adhesive sheet. The maximum height Rz of the adhesive surface 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 surface of the release film having a maximum height Rz of 400 nm or less, and thus has high surface smoothness. Therefore, when the adhesive sheet is attached to the adherend, the adhesive surface with the adherend has high surface smoothness, and adhesion with no optical distortion or suppressed optical distortion can be achieved.

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

[0010] In some preferred embodiments, the peeling force of the release film with respect to the pressure-sensitive adhesive sheet is 1 N / 50 mm or less. By configuring in this manner, when the release film is removed from the adhesive surface during use of the pressure-sensitive adhesive sheet, fine wavy patterns on the adhesive surface due to the so-called stick-slip phenomenon caused by peeling from the release film are suppressed, making it easier to obtain a smoother adhesive surface.

[0011] In some preferred embodiments, the thickness of the release film is within the range of 50 to 125 μm. By configuring in this way, the release film has a sufficient thickness, and it is possible to prevent an event (dent) in which the smoothness of the surface of the adhesive sheet is impaired through the release film. Such an event may be caused, for example, by foreign matter mixed between the release films when the adhesive sheet with the release film is wound into a roll. In addition, by setting the thickness of the release film to a predetermined value or less, removal from the adhesive sheet becomes smooth, and the adhesive surface of the adhesive sheet is likely to maintain high surface smoothness even after the release film is removed.

[0012] In some preferred embodiments, the pressure-sensitive adhesive sheet has a total light transmittance of 85% or more and a haze value of 1% or less. A pressure-sensitive adhesive sheet satisfying the above characteristics allows the adherend to be easily viewed through the pressure-sensitive adhesive sheet, and does not impair the visibility of the design or the like of the adherend.

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

[0014] In some other embodiments, the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet having a first adhesive surface and a second adhesive surface. The pressure-sensitive adhesive sheet with a release film has, as release films, a first release film arranged on the first adhesive surface and a second release film arranged on the second adhesive surface. The maximum height Rz of the first adhesive surface side surface S1 of the first release film is 1 and the maximum height Rz of the second adhesive surface S2 of the second release film 2 In this configuration, the effect of the technique disclosed herein can be preferably realized. In this configuration, the arithmetic mean roughness Ra 1 and the arithmetic mean roughness Ra of the surface S2 of the second release film 2 is preferably 30 nm or less. The peel strength of the first release film to the pressure-sensitive adhesive sheet and the peel strength of the second release film to the pressure-sensitive adhesive sheet may both be 1 N / 50 mm or less. Furthermore, the thickness of the first release film and the thickness of the second release film may each be within a range of 50 to 125 μm.

[0015] In still other embodiments, the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive 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 Rz of the first release surface of the release film is 1 and the maximum height Rz of the second release surface of the release film 2 In this configuration, the effects of the technology disclosed herein can be preferably realized. 1 and the arithmetic mean roughness Ra of the second peeled surface 2 Preferably, each of the peel strengths of the first release surface to the pressure-sensitive adhesive sheet and the second release surface to the pressure-sensitive adhesive sheet is 1 N / 50 mm or less.

[0016] In some preferred embodiments, the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer.Acrylic pressure-sensitive adhesives can achieve the desired adhesive properties and viscoelastic properties with excellent impact resistance without using additives such as softeners that can cause a decrease in transparency, or by limiting the amount of additives used, so that transparency, adhesive properties, and viscoelastic properties can be easily achieved.In addition, acrylic pressure-sensitive adhesives tend to have excellent discoloration resistance compared to, for example, rubber pressure-sensitive adhesives, and are also advantageous in terms of maintaining transparency over a long period of time.

[0017] In some preferred embodiments, the gel fraction of the pressure-sensitive adhesive layer is 30 to 95% by weight. When the gel fraction of the pressure-sensitive adhesive layer is 95% by weight or less, the pressure-sensitive adhesive sheet tends to have excellent step-following properties. Therefore, it can be well adhered to the surface of an adherend having steps. For example, when a logo mark or the like is printed on the surface of the adherend, the pressure-sensitive adhesive sheet can well follow the unevenness of the print without impairing visibility. In addition, when the gel fraction of the pressure-sensitive adhesive layer is 30% by weight or more, it tends to easily exhibit good adhesive properties and viscoelastic properties. For example, when the pressure-sensitive adhesive layer has the above gel fraction, it is less likely to cause dents and also tends to have excellent deformation resistance.

[0018] In some preferred embodiments, the pressure-sensitive adhesive layer has a storage modulus of 4×10 at 25° C. 4 The pressure-sensitive adhesive layer having the above storage modulus at 25° C. tends to have favorable heat resistance, and is likely to exhibit favorable adhesive properties such as deformation resistance.

[0019] In some preferred embodiments, the thickness of the pressure-sensitive adhesive sheet is 5 to 100 μm. Pressure-sensitive adhesive sheets having a thickness of 5 μm or more tend to have excellent conformability to unevenness and are easy to absorb deformation caused by foreign matter, etc. Furthermore, by setting the thickness to 100 μm or less, the pressure-sensitive adhesive sheet is less likely to warp, and a high adhesive surface smoothness is easily obtained.

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

[0021] In some preferred embodiments, the PSA sheet has an impact resistance of 2.0 J / 10 mm as measured by the following shear impact test. 2 That's all. By satisfying the above characteristics, the pressure-sensitive adhesive sheet can exhibit high impact resistance. For example, a pressure-sensitive adhesive sheet that satisfies the elastic modulus characteristics by the tensile test and the impact resistance characteristics can form a bond that is highly resistant to deformation and highly resistant to impact, and can therefore be preferably used for the purpose of joining or fixing members, for example. [Shear impact test] A shear impact test is performed using a pendulum type adhesive shear impact tester based on JIS K6855. As a measurement sample, the first surface of the 10 mm square adhesive sheet is attached to the center of a 25 mm square, 1.7 mm thick chemically strengthened glass plate, and then the second surface of the adhesive sheet is 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, then autoclaved (50°C, 0.5 MPa, 15 minutes), and the illuminance from the glass plate side is 300 mW / cm. 2 , Accumulated light intensity 3000mJ / cm 2 After irradiating ultraviolet light under the above conditions, the film is aged at 50°C for 48 hours before use. The measurement sample was fixed so that the stainless steel plate was on the bottom side, and a hammer was applied to the outer peripheral side of the glass plate at a hammer energy of 2.75 J and a hammer speed of 3.5 m / sec in an environment of 23°C and 50% RH. The absorbed energy [J] was measured to determine the impact resistance [J / 10 mm 2 ] is required.

[0022] In some preferred embodiments, the pressure-sensitive 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 the molecule, and the compound B1 more preferably has a molecular weight of 100 g / mol or more per ethylenically unsaturated group. The pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer can suitably form a bond having high deformation resistance and high impact resistance.

[0023] According to the adhesive sheet with release film disclosed herein, it is possible to realize an adhesive sheet with high surface smoothness on both adhesive surfaces, and therefore it is preferably used for fixing a transparent member to a member having an image display surface, a decorative surface, or a colored surface, which tend to require high visibility. For example, in an embodiment in which the decorative surface of a decorative film is fixed to a transparent member, the adhesive sheet has suppressed optical distortion, so that the decorative surface can be easily viewed through the adhesive sheet, and can function as a joining means that does not impair the design, beauty, or luxury of the decorative surface.

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

[0025] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a pressure-sensitive adhesive sheet with a release film according to one embodiment. [Diagram 2] FIG. 4 is a schematic cross-sectional view showing a pressure-sensitive adhesive sheet with a release film according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] A preferred embodiment of the present invention will be described below. Note that matters other than those specifically mentioned in this specification and necessary for carrying out the present invention can be understood by a person skilled in the art based on the teachings on carrying out the invention described in this specification and the common general knowledge at the time of filing. The present invention can be carried out based on the contents disclosed in this specification and the common general knowledge in the field. In addition, in the following drawings, components and parts having the same function may be described by using the same reference numerals, and duplicated descriptions may be omitted or simplified. In addition, the embodiments described in the drawings are schematic in order to clearly explain the present invention, and do not necessarily accurately represent the size or scale of the product actually provided.

[0027] In this specification, the term "adhesive" refers to a material that exhibits a soft solid (viscoelastic) state at temperatures near room temperature and that has the property of easily adhering to an adherend by pressure, as described above. The adhesive referred to here is generally a material having a complex tensile modulus E * (1Hz)<10 7 dyne / cm 2The material may be a material having the properties satisfying the above (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 an acrylic monomer, and is also called an acrylic polymer. The acrylic monomer refers to a monomer having at least one (meth)acryloyl group in one molecule. In this specification, "(meth)acryloyl" refers to acryloyl and methacryloyl in a comprehensive sense. Similarly, "(meth)acrylate" refers to acrylate and methacrylate, and "(meth)acrylic" refers to acrylic and methacrylic in a comprehensive sense. In this specification, the terms "mass" and "weight" are synonymous.

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

[0030] In addition, in this specification, "photocurable" refers to the property of being cured by irradiation with light such as ultraviolet light. For example, a photocurable adhesive composition refers to a composition that is cured by photocuring to become an adhesive or an adhesive layer. A photocurable adhesive layer refers to an adhesive layer that can be cured by irradiation with light such as ultraviolet light, and is used as a term indicating an adhesive layer before photocuring treatment of an adhesive layer that is completely cured by carrying out a photocuring treatment. A photocurable adhesive sheet is used as a term indicating an adhesive sheet having such a photocurable adhesive layer.

[0031] <Example of the composition of adhesive sheets with release film> One configuration example of the adhesive sheet with a release film disclosed herein is shown in FIG. 1. This adhesive sheet with a release film 1 includes 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 of this embodiment is a substrate-less double-sided adhesive sheet made 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 disposed on the first adhesive surface 10a of the adhesive sheet 10, and one surface (first adhesive surface side surface S1) 21a is in releasable contact with the first adhesive surface 10a of the adhesive sheet 10. The second release film 22 is disposed on the second adhesive surface 10b of the adhesive sheet 10, and one surface (second adhesive surface side surface S2) 22a of the second release film 22 is in contact with the second adhesive surface 10b of the adhesive sheet 10 in a releasable manner. 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 made of, for example, a silicone-based release treatment agent. In this way, the adhesive sheet 1 with release film is in a form in which 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, and the first adhesive surface 10a and the second adhesive surface 10b are exposed and attached to an adherend.

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

[0033] FIG. 2 shows a schematic structure of an adhesive sheet with a release film according to another embodiment. The adhesive sheet with a release film 2 shown in FIG. 2 includes a single-sided adhesive sheet (single-sided adhesive sheet) 10 and a release film 21. The single-sided adhesive sheet 10 includes an adhesive layer 12 and a support substrate 14 supporting the adhesive layer 12, one side of which (first side 12a of the adhesive layer 12) is an adhesive surface 10a, and the other side is a 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 substrate 14 (the surface opposite to the adhesive layer side surface 14a of the support substrate 14). The second side 12b of the adhesive layer 12 is fixed to the other side (adhesive layer side surface) 14a of the support substrate 14, and the adhesive layer side surface) 14a can be said to be a non-peeling surface (non-peeling surface). In this manner, the adhesive layer 12 is provided without any intention of separating it from the support substrate 14. On the other hand, surface (adhesive surface S1) 21a of release film 21 is a release surface similar to the first release film in Fig. 1, and is in releasable contact with adhesive surface 10a of adhesive layer 12 to protect 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 Fig. 2. Adhesive sheet roll 200 has adhesive sheet 10 including adhesive layer 12 and support substrate 14, and adhesive sheet 2 with release film having release film 21, wound around core (winding core) 50.

[0034] 1 shows an example of roll 100 in which adhesive sheet 1 with a release film is wound around core 50, roll 100 may be in a form not including core 50, i.e., a so-called coreless type roll in which adhesive sheet 1 with a release film is wound alone. The same applies to roll 200 shown in FIG. 2.

[0035] In addition, the adhesive sheet 1 (before use) shown in Figure 1 has a configuration in which the first adhesive surface 10a and the second adhesive surface 10b are protected by a first release film 21 and a second release film 22, at least the adhesive surface side of which is a surface (release surface) having releasability, respectively. However, it is also possible to omit the second release film 22 and use a release film 21 that has release surfaces on both sides, and roll up the adhesive sheet 1 to abut the second adhesive surface 10b against the back surface of the release film 21, so that the second adhesive surface 10b is also protected by the release film 21.

[0036] The adhesive sheet may be a substrate-less adhesive sheet as shown in FIG. 1, a substrate-attached single-sided adhesive sheet as shown in FIG. 2, or a substrate-attached double-sided adhesive sheet. Specifically, the adhesive sheet may be an adhesive sheet with a substrate in which a non-peeling substrate is built in (embedded). As the substrate, a plastic film, paper, nonwoven fabric, etc. may be used. Furthermore, although FIGS. 1 and 2 show an example in which the adhesive layer 10 has a single-layer structure, the configuration of the adhesive layer 10 is not limited thereto. For example, the adhesive layer may be configured to include two or more sub-adhesive layers made of the same or different adhesives.

[0037] <Release film> (Maximum height of adhesive surface Rz) The release film disclosed herein has a maximum height Rz of the adhesive side surface of 400 nm or less. This allows the adhesive surface of the adhesive sheet to have high surface smoothness. In addition, in a configuration in which a first and a second release film are disposed on each adhesive surface of the adhesive sheet, the maximum height Rz of the first adhesive side surface S1 of the first release film is 400 nm or less. 1 and the maximum height Rz of the second adhesive surface S2 of the second release film 2 In this way, each adhesive surface of the double-sided pressure-sensitive adhesive sheet has high surface smoothness, and when attached to an adherend, both adhesive surfaces can exhibit high surface smoothness.

[0038] The maximum height Rz of the adhesive side surface of the release film (the maximum height Rz of the first adhesive side surface S1 of the first release film 1 and the maximum height Rz of the second adhesive surface S2 of the second release film 2 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. In addition, from the viewpoint of ease of production 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 an embodiment having a first and second release film, the maximum height Rz of the first adhesive surface side surface S1 of the first release film 1 and the maximum height Rz of the second adhesive surface S2 of the second release film 2 may be the same or may be different.

[0039] (Arithmetic mean roughness Ra of adhesive side surface) In addition, it is preferable that the arithmetic mean roughness Ra of the adhesive surface of the release film is limited to a predetermined value or less (for example, approximately 100 nm or less, or even less than 50 nm) from the viewpoint of realizing an adhesive surface with high surface smoothness. In addition, in a configuration in which a first and a second release film are disposed on each adhesive surface of the adhesive sheet, the arithmetic mean roughness Ra of the first release film surface S1 is 1 and the arithmetic mean roughness Ra of the second adhesive surface S2 of the second release film 2 is suitably limited to, for example, about 100 nm or less (or even less than 50 nm). In some embodiments, the arithmetic mean roughness Ra of the adhesive side surface of the release film (the arithmetic mean roughness Ra of the first adhesive side surface S1 of the first release film) 1 and the arithmetic mean roughness Ra of the second adhesive surface S2 of the second release film 2The same applies hereinafter unless otherwise specified.) is preferably about 30 nm or less, and may be about 25 nm or less, about 20 nm or less, or about 18 nm or less. From the viewpoint of ease of production and handling of the release film, in some embodiments, the arithmetic mean roughness Ra may be, for example, about 5 nm or more, about 10 nm or more, or about 15 nm or more. In an embodiment having a first and second release film, the arithmetic mean roughness Ra of the first adhesive side surface S1 of the first release film is 1 and the arithmetic mean roughness Ra of the second adhesive surface S2 of the second release film 2 may be the same or may be different.

[0040] (Surface properties on the back) The maximum height Rz and arithmetic mean roughness Ra of the back surface (opposite side to the adhesive layer) of the release film (including the first release film and the second release film) are not particularly limited. The maximum height Rz of the back surface (opposite side to the adhesive layer) of the release film may be more than 400 nm (e.g., about 500 nm or more) or more 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 side to the adhesive layer) of the release film may be more than 30 nm (e.g., more than 35 nm, or even about 50 nm or more) 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 the selection of the film material, the molding method, surface treatment such as release treatment, etc. For example, adjustment of the smoothness of the layer constituting the release surface (antiblocking layer, hard coat layer, oligomer prevention layer, etc.), reduction or elimination of filler particles in the surface layer or release film substrate (particle-free), and adjustment of stretching conditions can be mentioned.

[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, a light interference type surface roughness measuring device is used, for example, a three-dimensional optical profiler (trade name "NewView7300", manufactured by ZYGO) or an equivalent product can be used. For example, a glass plate (a soda lime glass plate manufactured by MATSUNAMI, thickness 1.3 μm) is bonded and fixed with an adhesive to the surface opposite to the measurement surface of the release film, and the surface shape can be measured using a three-dimensional optical profiler (trade name "NewView7300", manufactured by ZYGO) under an environment of 23°C and 50% RH. The same applies to the examples described later. The specific measurement conditions and calculation method are the same as the measurement conditions for 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 release film and the second release film; the same applies hereinafter unless otherwise specified) may be selected from those having a maximum height Rz of the adhesive side surface of 400 nm or less. Non-limiting examples of release films that may 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 fluorine-based polymers (polytetrafluoroethylene, etc.) and polyolefin-based resins (polyethylene, polypropylene, etc.).

[0044] The release film disclosed herein may preferably have a release treatment layer on the 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 preferably be used. The thickness and method of forming the release treatment layer are not particularly limited, and may be set so that the adhesive surface of the release film exhibits appropriate releasability.

[0045] As the release film substrate, various plastic films can be used. In this specification, the plastic film is typically a non-porous sheet, and is a concept that is distinguished from, for example, nonwoven fabric (i.e., does not include nonwoven fabric).

[0046] Examples of the material of the 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 triacetyl cellulose, acetate resins, polysulfone resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, and cyclic polyolefin resins such as norbornene 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 a mixture of two or more of these resins can be used. Among them, a preferred release film substrate is a polyester resin film (e.g., a PET film) formed from a polyester resin.

[0047] The plastic film used as the release film substrate may be any of a non-stretched film, a uniaxially stretched film, and a biaxially stretched film. The plastic film may be a single-layer structure or a multi-layer structure including two or more sub-layers. The plastic film may contain known additives that can be used in the release film substrate of the pressure-sensitive adhesive sheet, such as antioxidants, antiaging agents, heat stabilizers, light stabilizers, ultraviolet absorbers, colorants such as pigments and dyes, lubricants, fillers, antistatic agents, and nucleating agents. In a multi-layered plastic film, each additive may be contained in all sub-layers, or may be contained in only some of the sub-layers.

[0048] In some preferred embodiments, the release film substrate (typically a plastic film) may preferably be one in which the content of particles such as inorganic particles (e.g., pigments, lubricants, fillers, etc.) in the layer on the release surface side is limited, or one that does not substantially contain such particles. Here, "substantially does not contain" 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). A release film having such a release film substrate tends 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 surface side may be 1 / 10 or less (e.g., 1 / 50 or less) of the particle content in layers other than the layer on the release surface side.

[0049] In embodiments having first and second release films, the first release film and the second release film may be made of the same material and have the same configuration, or may be made of different materials and have different configurations.

[0050] The thickness of the release film is not particularly limited, and may be, for example, about 10 μm to 500 μm. From the viewpoint of the strength and dimensional stability of the release film, the thickness of the release film is suitably 20 μm or more, preferably 30 μm or more, and may 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 about 50 μm or more, may be about 60 μm or more, or may be about 70 μm or more. This allows the release film to have a sufficient thickness, and can prevent the phenomenon (dents) in which the smoothness of the pressure-sensitive adhesive sheet surface is impaired through the release film. In addition, from the viewpoint of the handleability of the release film (for example, ease of rolling), the thickness of the release film is suitably 300 μm or less, preferably 250 μm or less, may be 200 μm or less, may be 150 μm or less, or may be 130 μm or less. In some preferred embodiments, the thickness of the release film is about 125 μm or less, may be about 115 μm or less, may be about 105 μm or less, or may be about 90 μm or less. By making the thickness of the release film equal to or less than a predetermined value, it is difficult for the film to leave a rolling mark when rolled, it is easy to remove from the pressure-sensitive adhesive sheet, and the adhesive surface of the pressure-sensitive adhesive sheet is likely to maintain a high surface smoothness even after the release film is removed.

[0051] In an embodiment having a first and a second release film, the first release film and the second release film may have the same thickness or different thicknesses. From the viewpoint of peeling workability, etc., it is preferable that the first release film and the second release film have different thicknesses, and it is preferable that the thickness of the thicker release film is about 1.1 times or more, for example about 1.25 times or more, the thickness of the thinner release film.

[0052] In addition, a carrier or auxiliary film may be attached to the back of the release film as necessary. The presence of such a back auxiliary film makes it easier to prevent dents even in an embodiment in which a thin release film is used, and can improve the workability of punching and other processes. As such a back auxiliary film, a known or commonly used adhesive tape with a resin film substrate can be used.

[0053] <Release film peel strength> The adhesive sheet with a release film disclosed herein preferably has a peeling force of the release film against the adhesive sheet limited to a predetermined value or less. This suppresses fine waving of the adhesive surface due to the so-called stick-slip phenomenon caused by peeling from the release film when the release film is removed 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 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 the protection and lifting prevention of the release film. The release strength of the release film can be adjusted by, for example, subjecting the surface of the release film to a release treatment.

[0054] In the embodiment having the first and second release films, the release force of the first release film and the release force of the second release film with respect to the adhesive sheet are preferably different from the viewpoint of peeling workability. For example, the release force of the release film on the heavy release side (e.g., the second release film) is suitably about 1.2 times or more than the release force of the release film on the light release side (e.g., the first release film), preferably about 1.4 times or more, may be about 1.5 times or more, or may be about 1.8 times or more. From the viewpoint of maintaining light release properties, the release force of the release film on the heavy release side (e.g., the second release film) is suitably about 3 times or less than the release force of the release film on the light release side (e.g., the first release film), and may be about 2 times or less.

[0055] The peel strength of the release film is measured by preparing a pressure-sensitive adhesive sheet with a release film cut to a length of 150 mm and a width of 50 mm, and measuring the peel strength under conditions of 23°C, 50% RH, a pulling speed of 300 mm / min, and a peel angle of 180°. Specifically, the peel strength is measured by the method described in the Examples below.

[0056] <Adhesive sheet> (Surface properties of adhesive surface) The adhesive sheet disclosed herein has an adhesive surface with a maximum height Rz limited to a predetermined value or less. A configuration with an adhesive surface designed to have a low maximum height Rz can have high surface smoothness and can be free of optical distortion or can have optical distortion suppressed. Such an adhesive sheet can be one that does not impair the design of the adherend, for example, its aesthetic appearance and luxurious feel, when the adherend surface is viewed through the adhesive sheet. 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 maximum heights Rz of the first adhesive surface and the second adhesive surface constituting the double-sided adhesive sheet are limited to a predetermined value or less. By having each adhesive surface of the double-sided adhesive sheet have high surface smoothness, adhesion can be achieved with no optical distortion or with optical distortion highly suppressed. For example, when one of the adherends is a transparent member and the other is an adherend having a design, the design of the adherend can be well viewed through the adhesive sheet.

[0057] The maximum height Rz of the adhesive surface of the adhesive sheet (including the first adhesive surface and the second adhesive surface; 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, particularly preferably about 400 nm or less, and may be less than 350 nm, may be less than 300 nm, or may be 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, may be about 50 nm or more, may be about 100 nm or more, or may be about 200 nm or more. In an embodiment 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] The adhesive surface of the adhesive sheet disclosed herein is preferably limited to a predetermined value or less in arithmetic mean roughness Ra. By providing an adhesive surface designed to have a low arithmetic mean roughness Ra, optical distortion can be highly suppressed. 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 are limited to a predetermined value or less. By having each adhesive surface of the double-sided adhesive sheet have high surface smoothness, adhesion without optical distortion or with optical distortion highly suppressed can be preferably realized.

[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 an embodiment 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 about the same or different.

[0060] The maximum height Rz and arithmetic mean roughness Ra of the adhesive surface of the adhesive sheet can be adjusted depending on 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, etc.

[0061] In addition, the maximum height Rz of the adhesive surface of the pressure-sensitive adhesive sheet can be the maximum height Rz of the surface of the adhesive layer constituting the pressure-sensitive adhesive sheet. Similarly, the arithmetic mean roughness Ra of the adhesive surface of the pressure-sensitive adhesive sheet can be the arithmetic mean roughness Ra of the surface of the adhesive layer constituting the pressure-sensitive 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 pressure-sensitive adhesive sheet can be adopted as the ranges and values ​​of the maximum height Rz and arithmetic mean roughness Ra of the surface of the adhesive layer.

[0062] In addition, the maximum height Rz and the arithmetic mean roughness Ra of the adhesive surface of the adhesive sheet are measured by using a non-contact surface roughness measuring device on the adhesive surface of the adhesive sheet after the release film is peeled off from the adhesive sheet with the release film. As the non-contact surface roughness measuring device, a surface roughness measuring device of the optical interference type is used, and for example, a three-dimensional optical profiler (trade name "NewView7300", manufactured by ZYGO) or its equivalent 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 when the measurement conditions are followed.

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

[0064] (Haze value) In some embodiments, the haze value of the pressure-sensitive adhesive sheet is, for example, about 10% or less, and is suitably about 3% or less. From the viewpoint of visibility of the adherend through the pressure-sensitive adhesive sheet, in some preferred embodiments, the haze value of the pressure-sensitive adhesive sheet is about 1% or less, more preferably about 0.8% or less, and even more preferably 0.5% or less. The lower limit of the haze value is theoretically 0%, and in practice, it may be more than about 0.0%. The "haze value" refers to the ratio of diffuse transmitted light to the total transmitted light when visible light is irradiated onto the measurement target. 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] The total light transmittance and haze value of the pressure-sensitive adhesive sheet can be adjusted by the composition (type of base polymer and added components), thickness, etc. of the pressure-sensitive adhesive sheet (typically the pressure-sensitive adhesive layer).

[0066] In addition, the total light transmittance of the pressure-sensitive adhesive sheet may be the total light transmittance of the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet.Similarly, the haze value of the pressure-sensitive adhesive sheet may be the haze value of the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet.Therefore, the ranges and values ​​described as the total light transmittance and haze value of the pressure-sensitive adhesive layer can be adopted, respectively.

[0067] The total light transmittance and haze value of the pressure-sensitive adhesive sheet can be measured by attaching the pressure-sensitive adhesive sheet to one side of a glass plate and using a haze meter. The haze meter can be a device named "HM-150N" manufactured by Murakami Color Research Laboratory or an equivalent device. Specifically, the measurements are performed by the method described in the examples below.

[0068] The adhesive sheet having the total light transmittance and haze value as described above may be a colored transparent or colorless transparent adhesive sheet. In this specification, the term "transparent" is used as a concept including translucency. In addition, the optical distortion reduction effect of the adhesive sheet according to the technology disclosed herein can be exhibited in a configuration in which at least a part of the adhesive sheet surface has a transparency to such an extent that it can be seen through the adhesive sheet, so 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 a glass plate (adhesive strength to glass) is, for example, about 1.0 N / 20 mm or more, and may be about 3.0 N / 20 mm or more (for example, about 5.0 N / 20 mm or more). From the viewpoint of bonding reliability, the adhesive strength to glass is preferably about 7.0 N / 20 mm or more, more preferably about 8.0 N / 20 mm or more, even more preferably about 9.0 N / 20 mm or more, and may be about 10.0 N / 20 mm or more, or may be about 11.0 N / 20 mm or more. The adhesive sheet having the above adhesive strength to glass can be preferably used for purposes such as bonding and fixing of members. From the viewpoint of easily achieving a balance with other properties, the adhesive strength to glass may be, for example, about 20 N / 20 mm or less, about 16.0 N / 20 mm or less, or about 12.0 N / 20 mm or less. The adhesive strength to glass can be adjusted by selecting the composition, thickness, etc. of the pressure-sensitive adhesive layer.

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

[0071] (Elastic modulus by tensile test) In some preferred embodiments, the adhesive sheet has a modulus of elasticity (also referred to as initial modulus of elasticity) of 3.0 MPa or more in a tensile test. An adhesive sheet with a higher modulus of elasticity tends to exhibit better deformation resistance. The adhesive sheet with the high modulus of elasticity can be preferably used for purposes such as joining and fixing members. For example, in an embodiment in which two members are joined via an adhesive sheet, the high deformation resistance of the adhesive sheet can be useful for precisely maintaining the relative positions of the two members. In addition, in an embodiment in which a film member and another member are joined via an adhesive sheet, the high deformation resistance of the adhesive sheet can be useful for suppressing a phenomenon in which the appearance of the laminate changes due to local pressure from the film member side (pressure deformation resistance). In an embodiment in which the adherend is a rigid member having transparency (for example, a glass member), it is particularly meaningful to suppress a change in appearance visually recognized from the adherend side.

[0072] In some preferred embodiments of the pressure-sensitive adhesive sheet, the elastic modulus may be, for example, 5.0 MPa or more, 7.0 MPa or more, 10.0 MPa or more, 15.0 MPa or more, or 20.0 MPa or more. The increase in the elastic modulus tends to improve the deformation resistance. The upper limit of the elastic modulus is not particularly limited. From the viewpoint of easily achieving a balance with other properties (for example, one or more properties selected from impact resistance, adhesion to glass, haze value, etc.), the elastic modulus is advantageously 150 MPa or less, preferably 120 MPa or less, may be 100 MPa or less, may be 80 MPa or less, or may be 60 MPa or less. The elastic modulus measured by the tensile test can be adjusted by selecting the composition of the pressure-sensitive adhesive sheet (typically the pressure-sensitive adhesive layer), etc. The elastic modulus measured by the tensile test is measured by the above-mentioned tensile test. More specifically, it is measured by the method described in the Examples below.

[0073] (Impact resistance) The adhesive sheet disclosed herein has an impact resistance of 2.0 J / 10 mm 2It is preferable that the above-mentioned pressure-sensitive adhesive sheet has a high impact resistance, and thus a highly reliable bond can be formed. This can be an advantageous feature of a pressure-sensitive adhesive sheet used for joining or fixing members, for example. Even if such a pressure-sensitive adhesive sheet is subjected to an impact due to, for example, a fall or a collision, it can withstand the impact and maintain a good bond between the member and the adherend.

[0074] In some preferred embodiments of the pressure-sensitive adhesive sheet, the impact resistance is, for example, 2.1 J / 10 mm 2 It may be more than 2.3J / 10mm 2 More than 2.5J / 10mm is fine. 2 More than 2.7J / 10mm is fine. 2 More than 3.0J / 10mm is also acceptable. 2 The pressure-sensitive adhesive sheet disclosed herein has an impact resistance of 3.3 J / 10 mm or more. 2 or more than 3.5J / 10mm 2 The embodiment above can also be preferably carried out. The upper limit of the impact resistance is not particularly limited. From the viewpoint of easily achieving a balance with other properties, the impact resistance is, for example, 20 J / 10 mm 2 It may be less than 15J / 10mm 2 Less than 10J / 10mm is also acceptable. 2 Less than 8.0J / 10mm is also acceptable. 2 Less than 6.0J / 10mm is also acceptable. 2 The impact resistance can be adjusted by selecting the composition, thickness, etc. of the pressure-sensitive adhesive layer. The impact resistance is measured by the above-mentioned shear impact test. 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 mode 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 suitably 5 μm or more, and may be, for example, 10 μm or more, preferably 20 μm or more, more preferably 25 μm or more, and may be more than 25 μm. In a thick adhesive sheet, optical distortion is likely to be reduced due to the stress dispersion ability of the adhesive layer. In addition, a thick adhesive sheet tends to have excellent step conformability and is likely to absorb deformation due to foreign matter, etc. Impact resistance also tends to be improved. The technology disclosed herein can be preferably implemented in an embodiment in which the thickness of the adhesive sheet is 30 μm or more. The thickness of the 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, when the thickness of the pressure-sensitive adhesive sheet is increased, the optical path that passes through the pressure-sensitive adhesive sheet is also increased, so that optical distortion is easily recognized. Therefore, in some embodiments, the thickness of the pressure-sensitive adhesive sheet is suitably set to, for example, 200 μm or less, and may 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 an adhesive layer composed of one or more types of adhesive selected from various known adhesives such as acrylic adhesives, rubber adhesives (natural rubber-based, synthetic rubber-based, and mixtures thereof), silicone adhesives, polyester adhesives, urethane adhesives, polyether adhesives, polyamide adhesives, and fluorine-based adhesives. Here, the acrylic adhesive refers to an adhesive having an acrylic polymer as the base polymer (the main component of the polymer component, i.e., a component contained in an amount of more than 50% by weight). The same applies to rubber adhesives and other adhesives.

[0077] (Polymer (A)) In some embodiments, the pressure-sensitive adhesive layer contains a polymer (A). Examples of materials that can be used as the 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 fluorine polymers, which are known in the field of pressure-sensitive adhesives. These can be used alone or in combination of two or more.

[0078] The weight ratio of the polymer (A) to the total weight of the adhesive layer is suitably 40% by weight or more from the viewpoint of adhesive properties such as impact resistance, 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 about 80% by weight or more, about 90% by weight or more, or about 97% by weight or more (for example, about 99% by weight or more). Adhesives with a high content of polymer (A) tend to have excellent transparency. In addition, the weight ratio of the polymer (A) to 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, or may be 87% by weight or less.

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

[0080] In some embodiments, (meth)acrylic acid C is the most abundant monomer component of the acrylic polymer (A). 1-20 The proportion of the alkyl ester is preferably more than 40% by weight, since this makes it easier to balance the properties, and may be, for example, 45% by weight or more, 50% by weight or more, 55% by weight or more, or 60% by weight or more. 1-20 The proportion of the alkyl ester may be 100% by weight, but is preferably 98% by weight or less in order to easily balance the properties, and may be, for example, 95% by weight or less, or may be 90% by weight or less. In some embodiments, the proportion of C in the total monomer components of the acrylic polymer (A) is 1-20 From the viewpoint of improving the cohesiveness of the pressure-sensitive adhesive layer, the proportion of the (meth)acrylic acid alkyl ester 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.

[0081] (Meth)acrylic acid C 1-20Non-limiting 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 ... and isopropyl (meth)acrylate. Examples of such acrylates include isooctyl, 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] Among 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 (meth)acrylic acid C 4-18 Examples of alkyl esters include n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA). 4-20 Other specific examples of alkyl esters include isononyl acrylate, n-butyl methacrylate (BMA), 2-ethylhexyl methacrylate (2EHMA), isostearyl acrylate (iSTA), etc. 4-20 The alkyl esters can be used alone or in combination of two or more.

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

[0084] In some embodiments, the monomer component constituting the acrylic polymer (A) is (meth)acrylic acid C 4-18 The monomer component may contain 40% by weight or more of alkyl ester. 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. In addition, from the viewpoint of enhancing the cohesiveness of the adhesive layer, (meth)acrylic acid C in the monomer components 4-18 The proportion of alkyl ester is suitably 99.5% by weight or less, may be 95% by weight or less, may be 85% by weight or less, or may be 75% by weight or less.

[0085] The monomer components constituting the acrylic polymer (A) may contain, in addition to the (meth)acrylic acid alkyl ester, other monomers (copolymerizable monomers) that are copolymerizable with the (meth)acrylic acid alkyl ester, if necessary. As the copolymerizable monomer, a monomer having a polar group (e.g., a carboxyl group, a hydroxyl group, a nitrogen atom-containing ring, etc.) or a monomer having a relatively high homopolymer glass transition temperature (e.g., 10°C or higher) can be suitably used. The monomer having a polar group can be useful for introducing a crosslinking point into the acrylic polymer (A) or for increasing the cohesive strength of the adhesive. The copolymerizable monomers can be used alone or in combination of two or more.

[0086] Non-limiting 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, and the like. Acid anhydride group-containing monomers: for example, maleic anhydride, itaconic anhydride. Hydroxyl group-containing monomers: for example, hydroxyalkyl (meth)acrylates such as 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, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. Monomers containing a sulfonic acid group or a phosphoric acid group: for example, styrene sulfonic acid, allyl sulfonic acid, sodium vinyl sulfonate, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid, 2-hydroxyethyl acryloyl 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, and glycidyl ether (meth)acrylate. Cyano group-containing monomers: for example, acrylonitrile, methacrylonitrile, etc. Isocyanate group-containing monomers: for example, 2-isocyanatoethyl (meth)acrylate. 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, and 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, and 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)acrylamide such as N-methoxymethyl (meth)acrylamide, N-methoxyethyl (meth)acrylamide, and N-butoxymethyl (meth)acrylamide; and others, N,N-dimethylaminopropyl (meth)acrylamide, N-(meth)acryloylmorpholine, and the like. Amino group-containing monomers: for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate. Monomers having an epoxy group: for example, glycidyl (meth)acrylate, methyl glycidyl (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-morpholinedione, 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)acryloyloxymethylene succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, N-(meth)acryloyl-8-oxyhexamethylene succinimide, and the like. Maleimides: for example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, and the like. Itaconimides: for example, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide, and the like. Aminoalkyl (meth)acrylates: for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate. Alkoxy group-containing monomers: for example, alkoxyalkyl (meth)acrylates (alkoxyalkyl (meth)acrylates) 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 (meth)acrylates (for example, alkoxypolyalkylene glycol (meth)acrylates) 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; alkoxysilyl group-containing vinyl compounds such as vinyltrimethoxysilane and vinyltriethoxysilane; and the like. 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 an alicyclic hydrocarbon group: for example, (meth)acrylates containing an alicyclic hydrocarbon group such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and adamantyl (meth)acrylate. (Meth)acrylic acid esters having an aromatic hydrocarbon group: for example, (meth)acrylates containing an aromatic hydrocarbon group such as phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate. Other examples include heterocyclic ring-containing (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate, halogen atom-containing (meth)acrylates such as vinyl chloride and fluorine atom-containing (meth)acrylates, silicon atom-containing (meth)acrylates such as silicone (meth)acrylate, and (meth)acrylic acid esters obtained from alcohols derived from terpene compounds.

[0087] When such a copolymerizable monomer is used, the amount of the copolymerizable monomer is not particularly limited, but is suitably 0.01% by weight or more of the total monomer components. From the viewpoint of better exerting the effect of using the copolymerizable monomer, the amount of the copolymerizable monomer may be 0.1% by weight or more of the total monomer components, or may be 0.5% by weight or more. Also, from the viewpoint of easily balancing the adhesive properties, the amount of the copolymerizable monomer is suitably 50% by weight or less of the total monomer components, and preferably 40% by weight or less.

[0088] In some embodiments, the monomer component constituting the acrylic polymer (A) may contain a monomer having a nitrogen atom. The use of a monomer having a nitrogen atom can increase the cohesive strength of the adhesive and favorably improve the peel strength after photocuring. A suitable example of the monomer having a nitrogen atom is a monomer having a nitrogen atom-containing ring. As the monomer having a nitrogen atom-containing ring, those exemplified above can be used, and for example, a monomer represented by the general formula (1): [ka] In the general formula (1), N-vinyl cyclic amide represented by the formula: 1 is a divalent organic group, specifically -(CH 2 ) n n is an integer of 2 to 7 (preferably 2, 3 or 4). Among them, N-vinyl-2-pyrrolidone can be preferably used. Another suitable example of the monomer having a nitrogen atom is (meth)acrylamide.

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

[0090] In some embodiments, the monomer components constituting the acrylic polymer (A) may contain a hydroxyl group-containing monomer. By using a hydroxyl group-containing monomer, the cohesive strength of the adhesive and the degree of crosslinking (for example, crosslinking by an isocyanate crosslinking agent) can be suitably adjusted. When using a hydroxyl group-containing monomer, the amount used is not particularly limited, and may be, for example, 0.01% by weight or more of the total monomer components, 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. In addition, from the viewpoint of suppressing the water absorption of the adhesive layer, in some embodiments, the amount of the hydroxyl group-containing monomer used is suitably, for example, 40% by weight or less of the total monomer components, and may be 30% by weight or less, 25% by weight or less, or 20% by weight or less. In some other embodiments, the amount of the hydroxyl group-containing monomer used may be, for example, 15% by weight or less, 10% by weight or less, or 5% by weight or less of the total monomer components.

[0091] In some embodiments, the ratio of the carboxyl group-containing monomer in the monomer components 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 a carboxyl group-containing monomer as a monomer component. Here, substantially not using a carboxyl group-containing monomer means that at least intentionally not using a carboxyl group-containing monomer. The pressure-sensitive adhesive layer containing the acrylic polymer (A) in which the amount of the carboxyl group-containing monomer used is limited as described above is preferable from the viewpoint of preventing metal corrosion. The pressure-sensitive adhesive sheet having such a pressure-sensitive adhesive layer may also be preferably used in an embodiment in which the pressure-sensitive adhesive layer contacts an adherend having a metal material, for example.

[0092] In some embodiments, the monomer component constituting the acrylic polymer (A) may contain an alicyclic hydrocarbon group-containing (meth)acrylate. This can increase the cohesive force of the adhesive and improve the peel strength after photocuring. As the alicyclic hydrocarbon group-containing (meth)acrylate, the above-mentioned examples can be used, and for example, cyclohexyl acrylate and isobornyl acrylate can be preferably used. When using an alicyclic hydrocarbon group-containing (meth)acrylate, the amount used is not particularly limited, and can be, for example, 1% by weight or more, 3% by weight or more, or 5% by weight or more of the entire monomer component. In some embodiments, the amount used of the alicyclic hydrocarbon group-containing (meth)acrylate may be 10% by weight or more, or 15% by weight or more of the entire monomer component. The upper limit of the amount used of the alicyclic hydrocarbon group-containing (meth)acrylate is suitably about 40% by weight or less, and may be, for example, 30% by weight or less, or 25% by weight or less (for example, 15% by weight or less, or even 10% by weight or less).

[0093] The polymerization method for forming (synthesizing) the polymer (A) from the monomer components is not particularly limited, and various conventionally known polymerization methods can be appropriately adopted. 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 irradiating light such as ultraviolet light (typically carried out in the presence of a photopolymerization initiator); radiation polymerization carried out by irradiating radiation such as β rays and γ rays; and other polymerization methods can be appropriately adopted. Two or more polymerization methods may be combined (for example, stepwise) to be carried out.

[0094] As the solvent for solution polymerization (polymerization solvent), for example, any one solvent selected from 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 (for example, monohydric alcohols having 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether; and ketones such as methyl ethyl ketone; or a mixed solvent of two or more of them can be used.

[0095] In the polymerization, a known or commonly used thermal polymerization initiator or photopolymerization initiator may be used depending on the polymerization method, polymerization mode, etc. Such polymerization initiators may be used alone or in appropriate combination of two or more.

[0096] The thermal polymerization initiator is not particularly limited, and examples thereof include azo polymerization initiators, peroxide initiators, redox initiators formed by combining peroxides with reducing agents, and substituted ethane initiators. More specifically, examples thereof include 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 initiators include, but are not limited to, azo initiators such as 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; redox initiators such as a combination of a persulfate and sodium hydrogen sulfite, and a combination of a peroxide and sodium ascorbate. Thermal polymerization can be preferably carried out at a temperature of, for example, about 20 to 100°C (typically 40 to 80°C), but is not limited thereto.

[0097] The photopolymerization initiator is not particularly limited, but examples of the photopolymerization initiator that can be used include 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, and thioxanthone-based photopolymerization initiators.

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

[0099] In the above polymerization, various conventionally known chain transfer agents (which may also be understood as molecular weight regulators or polymerization degree regulators) may be used as necessary. As the chain transfer agent, mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, thioglycolic acid, and α-thioglycerol may be used. Alternatively, a chain transfer agent that does not contain a sulfur atom (non-sulfur chain transfer agent) 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 benzylidene 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; benzyl hydrogens such as diphenylbenzene and triphenylbenzene; and the like. The chain transfer agent can be used alone or in combination of two or more. The technology disclosed herein can also be preferably implemented in an embodiment in which no chain transfer agent is used.

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

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

[0102] In this specification, the Tg of a polymer refers to the Tg calculated by the Fox formula based on the composition of the monomer components used in the preparation of the polymer. The Fox formula is a relational expression 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, as shown below. 1 / Tg=Σ(Wi / Tgi)

[0103] In the above Fox formula, Tg represents the glass transition temperature (unit: K) of the copolymer, Wi represents the weight fraction (copolymerization ratio by weight) of monomer i in the copolymer, and Tgi represents the glass transition temperature (unit: K) of a homopolymer of monomer i. When the target polymer for which Tg is 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 to calculate Tg is a value described in a publicly known document. For example, for the monomers listed below, the following values ​​are used as the glass transition temperatures of the homopolymers of the monomers. 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 homopolymers of monomers other than those listed above, the values ​​given in "Polymer Handbook" (3rd Edition, John Wiley & Sons, Inc., 1989) shall be used. When multiple values ​​are given in this document, the highest value shall be used.

[0106] The weight average molecular weight (Mw) of the 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 the polymer (A) is, for example, about 10 × 10 4 It is appropriate that the value is 20 x 10 or more. 4 More preferably, it is greater than 30×10 4 Ultra-fine, 40 x 10 4 Ultra-fine, even 50 x 10 4 The upper limit of Mw of the polymer (A) is about 500×10 4 From the viewpoint of adhesion to an adherend and peel strength, in some embodiments, the Mw of the polymer (A) can be, for example, 300×10 4 may be less than or equal to 150 x 10 4 Less than 100 x 10 4 Less than 90×10 is fine. 4 Less than 75×10 is fine. 4 The following is also fine. The above examples of Mw may be applied to the Mw of polymer (A) in the adhesive layer of the adhesive sheet disclosed herein, or may be applied to the Mw of polymer (A) in the adhesive composition used to form the adhesive layer.

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

[0108] (Photoreactive monomer (B)) In some preferred embodiments, the pressure-sensitive adhesive layer may contain a photoreactive monomer (B) in addition to the polymer (A) (for example, acrylic polymer (A)) as described above. As the photoreactive monomer (B), a compound having 2 or more ethylenically unsaturated groups in the molecule (hereinafter also referred to as "functional group number"). The upper limit of the functional group number of the compound used as the photoreactive monomer (B) is not particularly limited. The functional group number 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 an ethylenically unsaturated group with a functional group number of, for example, 2 to 10 may be used, a compound with a functional group number of 2 to 8 is preferably used, and a compound with a functional group number of 2 to 6 is more preferably used. The photoreactive monomer (B) may 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 the ethylenically unsaturated group with light (e.g., ultraviolet) irradiation or the like after application to an adherend. The adhesive sheet containing the photoreactive monomer (B) in the adhesive layer can increase the deformation resistance of the adhesive layer by curing the adhesive layer by ultraviolet irradiation or the like after application to an adherend. This can suitably achieve both good conformability to the surface shape of the adherend when applied to the adherend and high deformation resistance after application.

[0110] Examples of the ethylenically unsaturated group include, but are not limited to, an acryloyl group, a methacryloyl group, a vinyl group, and an allyl group. The two or more ethylenically unsaturated groups that the photoreactive monomer (B) has in its molecule may be the same group, or may be two or more different groups. From the viewpoint of photoreactivity, preferred ethylenically unsaturated groups include an acryloyl group and a methacryloyl group. Among them, an acryloyl group is preferred.

[0111] The functional group equivalent of the compound used as the photoreactive monomer (B) is not particularly limited. The 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) may be preferably used as the photoreactive monomer (B).

[0112] The functional group equivalent of the photoreactive monomer (B) is calculated by dividing the molecular weight [g / mol] of the photoreactive monomer (B) by the number of ethylenically unsaturated functional groups contained in the photoreactive monomer (B). The molecular weight of the photoreactive monomer (B) can be obtained, for example, by the GPC method as a weight average molecular weight converted into standard polystyrene. In addition, the molecular weight [g / mol] of the photoreactive monomer (B) may be the manufacturer's nominal value or a molecular weight calculated from the molecular structure.

[0113] The molecular weight of the photoreactive monomer (B) is not particularly limited and may be selected so that the desired effect is suitably exhibited. For example, a photoreactive monomer (B) having a molecular weight of about 20,000 or less can be used. From the viewpoint of preparation ease and coatability of the pressure-sensitive 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, typically 120 or more. From the viewpoint of processability and handleability of the pressure-sensitive 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 pressure-sensitive adhesive sheet disclosed herein, the amount of the photoreactive monomer (B) contained in the pressure-sensitive adhesive layer is not particularly limited, and can be appropriately set according to the target performance (for example, the elastic modulus of the pressure-sensitive adhesive layer after photocuring). In some embodiments in which the pressure-sensitive adhesive layer contains a polymer (A) and a photoreactive monomer (B), the amount of the photoreactive monomer (B) relative to 100 parts by weight of the polymer (A) contained in the pressure-sensitive adhesive layer may be, for example, 1 part by weight or more, and is suitably 3 parts by weight or more. From the viewpoint of easily increasing the elastic modulus of the pressure-sensitive adhesive layer after photocuring, the amount of the photoreactive monomer (B) relative to 100 parts by weight of the 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 handleability (e.g., processability) of the adhesive sheet, the amount of photoreactive monomer (B) per 100 parts by weight of polymer (A) is suitably 80 parts by weight or less, preferably 60 parts by weight or less, or may 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 pressure-sensitive adhesive layer preferably contains at least a compound B1 having a ring structure and two or more ethylenically unsaturated groups in the molecule as the photoreactive monomer (B). The pressure-sensitive adhesive layer containing the compound B1 of such a structure can effectively increase the deformation resistance of the pressure-sensitive adhesive layer by light irradiation. The ring in the ring structure may be an aliphatic ring or an aromatic ring. The ring may be a carbon ring or a heterocycle. The number of rings contained in one molecule of compound B1 may be 1 or 2 or more. The upper limit of the number of rings contained in compound B1 is not particularly limited, and may be, for example, 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. When compound B1 contains two or more rings, the rings may or may not form a condensed ring (typically a bicyclic or tricyclic condensed ring) by two or more rings. The 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 ring structure. Compound B1 can be used alone or in combination of two or more.

[0116] Compound B1 may preferably be a compound having a ring structure and two or more ethylenically unsaturated groups in the molecule and a functional group equivalent of 100 g / mol or more. A pressure-sensitive adhesive sheet containing compound B1 satisfying the above-mentioned functional group equivalent in the pressure-sensitive adhesive layer can suitably form a bond with high deformation resistance and high impact resistance. The reason for obtaining such an effect is not particularly limited, but it is considered that compound B1 can effectively increase the elastic modulus of the pressure-sensitive adhesive layer after light irradiation due to the rigidity of the ring structure, and can impart deformation resistance, while the functional group equivalent of compound B1 is a predetermined value or more, so that the distance between crosslinking points is maintained, and a crosslinked structure with high impact resistance can be formed. 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. The impact resistance tends to improve by increasing the functional group equivalent of compound B1. In addition, the functional group equivalent of compound B1 may be, for example, 10000g / mol or less, 8000g / mol or less, 5000g / mol or less, 3000g / mol or less, or 2000g / mol or less. In some embodiments, from the viewpoint of photocurability, etc., the functional group equivalent of compound B1 is preferably 800g / mol or less, more preferably 600g / mol or less. In some embodiments, the functional group equivalent of compound B1 may be 500g / mol or less, 400g / mol or less, or 300g / mol or less.

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

[0118] Compound B1 may have a functional group other than the ethylenically unsaturated group. Examples of the functional group other than the ethylenically unsaturated group include a hydroxyl group, a carboxyl group, and an amino group. Suitable examples of the functional group other than the ethylenically unsaturated group include a hydroxyl group and an amino group.

[0119] Examples of the compound B1 include bisphenol A type epoxy (meth)acrylates such as bisphenol A glycidyl ether (meth)acrylic acid adduct, bisphenol A glycidyl amine (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 glycidyl amine (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, bisphenol E Bisphenol E type epoxy (meth)acrylates such as glycidylamine (meth)acrylic acid adduct and bisphenol E glycidyl ester (meth)acrylic acid adduct; 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)fluoren-di(meth)acrylate, 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluoren-di(meth)acrylate (meth)acrylates containing a fluorene skeleton, such as acrylate; aliphatic rings (alicyclic condensed rings), such as 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 phthalic acid type epoxy (meth)acrylate, hydrogenated terpene phenol (meth)acrylate, and 1,4-cyclohexane dimethanol diglycidyl ether (meth)acrylate.(Meth)acrylates having the above structure; (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 terpene phenol 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 products of any of the above materials (e.g., amine modified products, acid modified products, halogen modified products); and the like, but are not limited thereto. In some embodiments, a compound B1 having an aromatic carbon ring may be preferably employed. Suitable examples of the 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 modified products thereof (eg, amine modified products).

[0120] Examples of commercially available products that can be used as compound B1 include, but are not limited to, products manufactured by Shin-Nakamura Chemical Co., Ltd. under the trade names "A-DCP" and "A-BPE-4", products manufactured by Osaka Organic Chemical Industry Co., Ltd. under the trade names "Viscoat #540" and "Viscoat #700HV", products manufactured by Nippon Kayaku Co., Ltd. under the trade names "Epoxy Ester 3000A" and "Epoxy Ester 80MFA" manufactured by Kyoeisha Chemical Co., Ltd., and products manufactured by Daicel Allnex under the trade names "EBECRYL 3700", "EBECRYL 3703", and "EBECRYL 3603".

[0121] The amount of compound B1 relative to 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 easily obtaining an adhesive layer that balances deformation resistance and impact resistance, in some embodiments, the amount of compound B1 relative to 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. In addition, from the viewpoint of the cohesiveness of the adhesive layer before photocuring and the handleability of the adhesive sheet, the amount of compound B1 relative to 100 parts by weight of polymer (A) is suitably 80 parts by weight or less, preferably 60 parts by weight or less, and may be 50 parts by weight or less, 40 parts by weight or less, 35 parts by weight or less, 25 parts by weight or less, or 15 parts by weight or less.

[0122] In some embodiments, the pressure-sensitive adhesive layer may contain, as the photoreactive monomer (B), a compound B2 having two or more functional groups and no ring structure in the molecule. Compound B2 is preferably used in combination with compound B1. This can adjust the crosslinked structure of the pressure-sensitive adhesive layer to form a bond that more suitably balances deformation resistance and impact resistance. Compound B2 can be used alone or in combination of two or more.

[0123] The number of functional groups of compound B2 may be, for example, 50 or less, 40 or less, 30 or less, 20 or less, or 15 or less. The number of functional groups of compound B2 used in some embodiments may be, for example, 2 to 10, preferably 3 to 10, 3 to 8, or 4 to 6. For example, in an embodiment in which a compound having 2 functional groups is used as compound B1, it may be advantageous to use compound B2 having 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 the 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 the compound B2 may be, for example, 600 g / mol or less, and from the viewpoint of improving the photocurability and hardness of the cured product, 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. The functional group equivalent of the compound B2 is typically 50 g / mol or more, preferably 60 g / mol or more, 70 g / mol or more, 80 g / mol or more, or 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, hydroxypivalic acid neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, EO modified products or PO modified products of any of the above-mentioned materials, and the like.

[0126] In the embodiment using the compound B2, the amount of the compound B2 relative to 100 parts by weight of the 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 easily obtaining an adhesive layer that balances deformation resistance and impact resistance, in some embodiments, the amount of the compound B2 relative to 100 parts by weight of the 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. In addition, from the viewpoint of suppressing a decrease in adhesion to the adherend due to excessive crosslinking, in some embodiments, the amount of the compound B2 relative to 100 parts by weight of the polymer (A) is, for example, appropriate 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 an embodiment in which compound B1 and compound B2 are used in combination, compound B2 may preferably be a compound having three or more functional groups and a smaller functional group equivalent than that of compound B1 used in combination therewith. In some embodiments, the functional group equivalent FE 1 Functional group equivalent FE of compound B2 2 Ratio of (FE 2 / FE 1 ) may be, for example, 0.9 or less, 0.7 or less, 0.5 or less, or 0.4 or less. According to this embodiment, the effect of improving the elastic modulus by the photoreactive monomer (B) can be efficiently exhibited. The above ratio (FE 2 / FE 1 The lower limit of ) is not particularly limited, and may be, for example, 0.01 or more, 0.1 or more, or 0.2 or more.

[0128] In the embodiment in which compound B1 and compound B2 are used in combination, the amount of compound B1 used W 1 The amount of compound B2 used W 2 Weight ratio (W 2 / W 1 ) is not particularly limited. In some embodiments, the weight ratio (W 2 / W1 ) may be, for example, 0.05 to 10, 0.1 to 5, 0.2 to 3, or 0.3 to 2. 2 / W 1 ) in any of the above ranges, the effect of using Compound B1 and Compound B2 in combination tends to be favorably exhibited.

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

[0130] In some embodiments, the photoreactive monomer (B) may be contained in the pressure-sensitive adhesive layer in a free form. Such a pressure-sensitive adhesive layer may be suitably formed using a pressure-sensitive adhesive composition containing the photoreactive monomer (B) in a free form. Here, the term "free form" refers to the photoreactive monomer (B) not being chemically bonded to other components (e.g., polymer (A)) contained in the pressure-sensitive adhesive layer or the pressure-sensitive adhesive composition. A pressure-sensitive adhesive composition containing the photoreactive monomer (B) in a free form may be advantageous in terms of ease of preparation and suppression of gelation.

[0131] In some other embodiments, at least a part of the photoreactive monomer (B) may be included in the pressure-sensitive adhesive layer in a form chemically bonded to other components (e.g., polymer (A), a crosslinking agent described below, etc.) included in the pressure-sensitive adhesive layer or the pressure-sensitive adhesive composition from the viewpoint of improving the processability of the pressure-sensitive adhesive sheet. The chemical bond may be, for example, a bond formed by a reaction between a functional group F1 other than an ethylenically unsaturated group contained in the molecule of the photoreactive monomer (B) and a functional group F2 contained in the molecule of the other component and capable of reacting with the functional group F1. The other component may be a crosslinking agent, and the photoreactive monomer (B) may be bonded to the polymer (A) via the crosslinking agent.

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

[0133] The Tg of the acrylic oligomer is not particularly limited, and may be, for example, about 20°C or more and 300°C or less. The Tg may be, for example, about 30°C or more, about 40°C or more, about 60°C or more, about 80°C or more, or about 100°C or more. When the Tg of the acrylic oligomer is high, the effect of improving the cohesive force generally tends to be high. In addition, from the viewpoint of anchoring to the support substrate and impact absorption, the Tg of the acrylic oligomer may be, for example, about 250°C or less, about 200°C or less, about 180°C or less, or about 150°C or less. The Tg of the acrylic oligomer is a value calculated based on the Fox formula, like the Tg of the polymer (A).

[0134] The Mw of the acrylic oligomer is not particularly limited, and may be, for example, about 1000 or more, suitably about 1500 or more, about 2000 or more, or about 3000 or more. The Mw of the acrylic oligomer may be, for example, less than about 30000, suitably less than about 10000, less than about 7000, or less than about 5000. When the Mw is within the above range, the effect of improving the cohesiveness of the pressure-sensitive adhesive layer and the adhesion to the adjacent surface is easily exhibited. The Mw of the acrylic oligomer can be measured by GPC and calculated as a value converted into standard polystyrene. Specifically, for example, it can be measured using 2 columns of TSKgel GMH-H (20) on a HPLC 8020 manufactured by Tosoh Corporation, with a flow rate of about 0.5 mL / min in tetrahydrofuran solvent.

[0135] As the monomer component constituting the acrylic oligomer, the above-mentioned various (meth)acrylic acids C 1-20 Examples of (meth)acrylate monomers include alkyl esters, the various alicyclic hydrocarbon group-containing (meth)acrylates described above, the various aromatic hydrocarbon group-containing (meth)acrylates described above, and (meth)acrylates obtained from alcohols derived from terpene compounds. These can be used alone or in combination of two or more.

[0136] From the viewpoint of improving adhesiveness, it is preferable that the acrylic oligomer contains, as a monomer unit, an acrylic monomer having a relatively bulky structure, such as an alkyl (meth)acrylate having a branched structure such as isobutyl (meth)acrylate or t-butyl (meth)acrylate, an alicyclic hydrocarbon group-containing (meth)acrylate, or an aromatic hydrocarbon group-containing (meth)acrylate, etc. In addition, when ultraviolet light is used in synthesizing the acrylic oligomer or in preparing the adhesive layer, a monomer having a saturated hydrocarbon group at the ester end is preferable in terms of being less likely to cause polymerization inhibition, and for example, an alkyl (meth)acrylate having a branched structure such as an alkyl group or a saturated alicyclic hydrocarbon group-containing (meth)acrylate can be suitably used.

[0137] The proportion of (meth)acrylate monomers in all 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, or even 90% by weight or more). In some preferred embodiments, the acrylic oligomer has a monomer composition substantially consisting of one or more (meth)acrylate monomers. The monomer components are an alicyclic hydrocarbon group-containing (meth)acrylate and (meth)acrylic acid C. 1-20 When the alkyl ester is included, the weight ratio thereof is not particularly limited. In some embodiments, the alicyclic hydrocarbon group-containing (meth)acrylate / (meth)acrylic acid C 1-20 The weight ratio of the alkyl esters can be, for example, 10 / 90 or more, 20 / 80 or more, or 30 / 70 or more, and can be 90 / 10 or less, 80 / 20 or less, or 70 / 30 or less.

[0138] In addition to the above (meth)acrylate monomer, functional group-containing monomers can be used as monomer components constituting the acrylic oligomer, if necessary. Examples of functional group-containing monomers include monomers having nitrogen atom-containing heterocycles such as N-vinyl-2-pyrrolidone and N-acryloylmorpholine; amino group-containing monomers such as N,N-dimethylaminoethyl (meth)acrylate; amide group-containing monomers such as N,N-diethyl (meth)acrylamide; carboxy group-containing monomers such as AA and MAA; and hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate. These functional group-containing monomers can be used alone or in combination of two or more. When a functional group-containing monomer is used, the ratio of the functional group-containing monomer to the total monomer components constituting the acrylic oligomer can be, for example, 1% by weight or more, 2% by weight or more, or 3% by weight or more, and can be, for example, 15% by weight or less, 10% by weight or less, or 7% by weight or less. The acrylic oligomer may not use a functional group-containing monomer.

[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), and copolymers of CHMA and AA.

[0140] The acrylic oligomer can be formed by polymerizing its 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 used in an appropriate mode. The type of polymerization initiator (e.g., azo-based polymerization initiator) that can be used as necessary is generally as exemplified for the synthesis of the acrylic polymer (A), and the amount of the polymerization initiator and the amount of the chain transfer agent (e.g., mercaptans) that is optionally used are appropriately set based on technical common sense so as to obtain a desired molecular weight, so detailed explanations are omitted.

[0141] When the adhesive layer or adhesive composition contains an acrylic oligomer, the content can be, for example, 0.01 parts by weight or more relative to 100 parts by weight of the polymer (A), and from the viewpoint of obtaining a higher effect, it may be 0.05 parts by weight or more, 0.1 parts by weight or more, or 0.2 parts by weight or more. From the viewpoint of compatibility with the polymer (A), the content of the acrylic oligomer relative to 100 parts by weight of the polymer (A) is suitably 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, 5 parts by weight or less, or 1 part by weight or less. The adhesive layer or adhesive composition may not contain an acrylic oligomer.

[0142] (Crosslinking agent) A crosslinking agent may be used in the adhesive layer as necessary. In the adhesive sheet disclosed herein, the crosslinking agent is typically contained in the adhesive layer in a form after crosslinking reaction. By using a crosslinking agent, the cohesive strength of the adhesive layer can be appropriately adjusted. In addition, for example, in an adhesive sheet containing a photoreactive monomer (B) in the adhesive layer, by using a crosslinking agent in combination with 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 so that the crosslinking agent exerts an appropriate crosslinking function in the adhesive layer, for example, according to the composition of the adhesive composition. 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, and amine-based crosslinking agents. These can be used alone or in combination of two or more.

[0144] As the isocyanate-based crosslinking agent, a polyfunctional isocyanate compound having two or more functionalities can be used. For example, aromatic isocyanates such as tolylene diisocyanate, xylene diisocyanate, polymethylene polyphenyl diisocyanate, tris(p-isocyanatophenyl)thiophosphate, diphenylmethane diisocyanate, etc., alicyclic isocyanates such as isophorone diisocyanate, etc., aliphatic isocyanates such as hexamethylene diisocyanate, etc. can be mentioned. 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"), an isocyanurate of hexamethylene diisocyanate (manufactured by Tosoh Corporation, product name "Coronate HX"), and trimethylolpropane / xylylene diisocyanate adduct (manufactured by Mitsui Chemicals, Inc., product name "Takenate D-110N").

[0145] As the epoxy crosslinking agent, those having two or more epoxy groups in one molecule can be used without any particular limitation. An epoxy crosslinking agent having 3 to 5 epoxy groups in one molecule is preferable. Specific examples of the epoxy crosslinking agent include N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, polyglycerol polyglycidyl ether, and the like. Commercially available epoxy crosslinking agents include Mitsubishi Gas Chemical Company's product names "TETRAD-X" and "TETRAD-C", DIC Corporation's product name "Epicron CR-5L", Nagase ChemteX Corporation's product name "Denacol EX-512", Nissan Chemical Industries' product name "TEPIC-G", and the like.

[0146] As the oxazoline-based crosslinking agent, any agent having one or more oxazoline groups in one molecule can be used without any particular limitation. Examples of the aziridine crosslinking agent include trimethylolpropane tris[3-(1-aziridinyl)propionate], trimethylolpropane tris[3-(1-(2-methyl)aziridinylpropionate)], and the like. As the carbodiimide crosslinking agent, a low molecular weight compound or a high molecular weight compound 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, dilauroylperoxide, di-n-octanoylperoxide, 1,1,3,3-tetramethylbutylperoxyisobutyrate, and dibenzoylperoxide. Among these, examples of peroxides that are particularly excellent in crosslinking reaction efficiency include di(4-t-butylcyclohexyl)peroxydicarbonate, dilauroylperoxide, and dibenzoylperoxide. In addition, when peroxides are used as the polymerization initiator, it is also possible to use the remaining peroxides that are not used in the polymerization reaction in the crosslinking reaction. In this case, the remaining amount of peroxide is quantified, and if the ratio of peroxide is less than the predetermined amount, peroxide is added as necessary to reach the predetermined amount. The amount of peroxide can be quantified by the method described in Japanese Patent No. 4971517.

[0148] When a crosslinking agent is used, the amount used (when two or more crosslinking agents are used, the total amount of the crosslinking agents) is not particularly limited. From the viewpoint of realizing a pressure-sensitive adhesive that exhibits adhesive properties such as adhesive strength and cohesive strength in a well-balanced manner, the amount of the crosslinking agent used is suitably about 5 parts by weight or less relative to 100 parts by weight of the polymer (A), and may 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 an embodiment in which a crosslinking agent and a photoreactive monomer (B) are used in combination, from the viewpoint of favorably exhibiting the effects of such combined use, the amount of the crosslinking agent used relative to 100 parts by weight of the 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 the crosslinking agent used is not particularly limited, and it may be used in an amount greater than 0 parts by weight relative to 100 parts by weight of the polymer (A). In some embodiments, the amount of the crosslinking agent used can be, for example, 0.001 parts by weight or more, optionally 0.01 parts by weight or more, or optionally 0.03 parts by weight or more, relative to 100 parts by weight of the polymer (A).

[0149] The technology disclosed herein can be preferably implemented in an embodiment using at least an isocyanate-based crosslinking agent as a crosslinking agent. The isocyanate-based crosslinking agent may be used in combination with other crosslinking agents. In an embodiment using an isocyanate-based crosslinking agent, the amount of the isocyanate-based crosslinking agent used relative to 100 parts by weight of the 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. In addition, the amount of the isocyanate-based crosslinking agent used relative to 100 parts by weight of the 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 promote the crosslinking reaction more effectively. Examples of the crosslinking catalyst include metal-based crosslinking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, nursem ferric, butyltin oxide, and dioctyltin dilaurate. Among them, tin-based crosslinking catalysts such as dioctyltin dilaurate are preferred. The amount of the crosslinking catalyst used is not particularly limited. The amount of the crosslinking catalyst used can be, for example, about 0.0001 parts by weight or more, about 0.001 parts by weight or more, about 0.005 parts by weight or more, and about 1 part by weight or less, about 0.1 parts by weight or less, about 0.05 parts by weight or less, relative to 100 parts by weight of the polymer (A).

[0151] The adhesive composition used for forming the adhesive layer can contain a compound that generates keto-enol tautomerism as a crosslinking retarder, if desired. For example, a compound that generates keto-enol tautomerism can be preferably used in an adhesive composition that contains an isocyanate-based crosslinking agent or an adhesive composition that can be used by blending an isocyanate-based crosslinking agent. This can provide the effect of extending the pot life of the adhesive composition. As the compound that generates keto-enol tautomerism, various β-dicarbonyl compounds can be used. Specific examples include β-diketones such as acetylacetone and 2,4-hexanedione; acetoacetates such as methyl acetoacetate and ethyl acetoacetate; propionyl acetates such as ethyl propionyl acetate; isobutyryl acetates such as ethyl isobutyryl acetate; malonates such as methyl malonate and ethyl malonate; and the like. Among them, acetylacetone and acetoacetates are preferred. The compound that generates keto-enol tautomerism can be used alone or in combination of two or more. The amount of the compound that causes keto-enol tautomerization used may be, for example, 0.1 parts by weight or more and 20 parts by weight or less, and appropriately 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 may be 1 part by weight or more and 5 parts by weight or less, relative to 100 parts by weight of polymer (A).

[0152] (Silane coupling agent) The adhesive layer of the adhesive sheet disclosed herein may contain a silane coupling agent if desired. The use of a silane coupling agent can improve the peel strength of the adhesive sheet from an adherend (e.g., a glass plate). The 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 contained in the adhesive composition in a free form from the viewpoint of gelation inhibition and the like. In some embodiments, the silane coupling agent is preferably contained in the adhesive layer of the adhesive sheet disclosed herein in a free form. The silane coupling agent contained in the adhesive layer in such a form can effectively contribute to improving the peel strength. Here, the "free form" means that the silane coupling agent is not chemically bonded to other components contained in the adhesive composition or the adhesive layer.

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

[0154] The amount of the silane coupling agent used when using it can be set so as to obtain the desired effect of use, and is not particularly limited. In some embodiments, the amount of the silane coupling agent used may be, for example, 0.001 parts by weight or more relative to 100 parts by weight of the 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. In addition, from the viewpoint of suppressing gelation of the pressure-sensitive adhesive composition, the amount of the silane coupling agent used relative to 100 parts by weight of the polymer (A) is suitably 3 parts by weight or less, may be 1 part by weight or less, or may be 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 necessary for the purpose of improving or imparting photocurability. As the photopolymerization initiator, a ketal-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, a benzoin ether-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, an α-ketol-based photopolymerization initiator, an aromatic sulfonyl chloride-based photopolymerization initiator, a photoactive oxime-based photopolymerization initiator, a benzoin-based photopolymerization initiator, a benzyl-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, a thioxanthone-based photopolymerization initiator, etc., may be used, as well as the photopolymerization initiators exemplified as those usable in the synthesis of the polymer (A). The photopolymerization initiator may be used alone or in appropriate combination of two or more.

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

[0157] The content of the photopolymerization initiator in the adhesive layer is not particularly limited and can be set so that the desired effect is appropriately exhibited. In some embodiments, the content of the photopolymerization initiator can be, for example, about 0.005 parts by weight or more, suitably 0.01 parts by weight or more, preferably 0.05 parts by weight or more, may be 0.10 parts by weight or more, may be 0.15 parts by weight or more, or may be 0.20 parts by weight or more, relative to 100 parts by weight of the polymer (A) contained in the adhesive layer. The photocuring property of the adhesive layer tends to improve by increasing the content of the photopolymerization initiator. In addition, the content of the photopolymerization initiator relative to 100 parts by weight of the polymer (A) is suitably 10 parts by weight or less, preferably 7 parts by weight or less, may be 5 parts by weight or less, 3 parts by weight or less, may be 2 parts by weight or less, or may be 1 part by weight or less. It may be advantageous from the viewpoint of improving the storage stability (for example, stability against photodegradation) of the adhesive sheet if the content of the photopolymerization initiator is not too high.

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

[0159] The adhesive layer or adhesive composition of the adhesive sheet disclosed herein may contain, as necessary, various additives common in the field of adhesives, such as tackifier resins (e.g., rosin-based, petroleum-based, terpene-based, phenol-based, ketone-based, etc. tackifier resins), viscosity adjusters (e.g., thickeners), leveling agents, plasticizers, fillers, colorants such as pigments and dyes, stabilizers, preservatives, antiaging agents, etc., as other optional components. As for such various additives, those conventionally known can be used in the usual manner, and detailed explanations are omitted since they do not particularly characterize the present invention. The technology disclosed herein can exhibit good adhesive strength without using the tackifier resin. Therefore, in some embodiments, the content of the tackifier resin in the pressure-sensitive adhesive layer or pressure-sensitive adhesive composition can be, for example, less than 10 parts by weight, or even less than 5 parts by weight, relative to 100 parts by weight of the polymer (A). The content of the tackifier resin can 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 pressure-sensitive adhesive layer or pressure-sensitive adhesive composition can be one that does not contain a tackifier resin.

[0160] From the viewpoint of transparency, it is preferable that the amount of components other than the polymer (A) and the photoreactive monomer (B) used as necessary in the pressure-sensitive adhesive layer (and thus the pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive layer) is limited. In the technology disclosed herein, the amount of components other than the polymer (A) and the photoreactive monomer (B) in the pressure-sensitive adhesive layer is about 30% by weight or less, appropriately about 15% by weight or less, and preferably about 12% by weight or less (e.g., about 10% by weight or less). In the pressure-sensitive adhesive sheet according to some embodiments, the amount of components other than the polymer (A) and the photoreactive monomer (B) in the pressure-sensitive adhesive layer may be about 5% by weight or less, about 3% by weight or less, or about 1.5% by weight or less (e.g., about 1% by weight or less).

[0161] <Form of Pressure-Sensitive Adhesive Composition> The adhesive layer can be formed using an adhesive composition containing the monomer components of the above-mentioned composition in the form of a polymer, an unpolymerized product (i.e., a form in which the polymerizable functional group is unreacted), or a mixture thereof. The adhesive composition can be in various forms, such as a composition containing an adhesive (adhesive component) in an organic solvent (solvent-based adhesive composition), a composition in the form in which an adhesive is dispersed in an aqueous solvent (water-dispersed adhesive composition), a composition prepared to form an adhesive by curing with active energy rays such as ultraviolet rays or radiation (active energy ray-curable adhesive composition), and a hot melt adhesive composition that is applied in a heated and 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, a solvent-based adhesive composition can be preferably adopted in some embodiments. The solvent-based adhesive composition can be preferably prepared using a polymer (A) that is a polymer obtained by solution polymerization of a monomer component.

[0162] In this specification, the term "active energy rays" refers to energy rays having energy capable of inducing chemical reactions such as polymerization reactions, crosslinking reactions, decomposition of initiators, etc. Examples of active energy rays include light such as ultraviolet rays, visible light, and infrared rays, and radiation such as α rays, β rays, γ rays, electron beams, neutron beams, and X-rays.

[0163] The pressure-sensitive adhesive composition typically contains at least a part of the monomer components of the composition (which may be a part of the type of monomer or a part of the amount) in the form of a polymer. The polymerization method for forming the polymer is not particularly limited, and various conventionally known polymerization methods can be appropriately adopted. 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 irradiating light such as ultraviolet light (typically carried out in the presence of a photopolymerization initiator); radiation polymerization carried out by irradiating radiation such as β-rays and γ-rays; and the like can be appropriately adopted. In these polymerization methods, the mode of polymerization is not particularly limited, and the polymerization can be carried out by appropriately selecting a conventionally known monomer supply method, polymerization conditions (temperature, time, pressure, light irradiation amount, radiation irradiation amount, etc.), and materials used other than the monomer (polymerization initiator, surfactant, etc.), etc.

[0164] In the polymerization, a known or commonly used photopolymerization initiator or thermal polymerization initiator can be used depending on the polymerization method, polymerization mode, etc. Examples of photopolymerization initiators and thermal polymerization initiators are as described above, so duplicated explanations will be omitted. Such polymerization initiators can be used alone or in appropriate combination of two or more types.

[0165] (Adhesive composition containing polymerized and unpolymerized monomer components) The pressure-sensitive adhesive composition according to some embodiments contains a polymerization product of a monomer mixture containing at least a part of the monomer components (raw material monomers) of the composition. Typically, the composition contains a part of the monomer components in the form of a polymer, and the remaining part in the form of an unpolymerized product (unreacted monomer). The polymerization product of the monomer mixture can be prepared by at least partially polymerizing the monomer mixture. The polymerization reaction product is preferably a partial polymer of the monomer mixture. Such a partial polymer is a mixture of a polymer derived from the monomer mixture and an unreacted monomer, and typically has a syrup-like appearance (viscous liquid). Hereinafter, a partial polymer having such properties may be referred to as "monomer syrup", "polymer syrup", or simply as "syrup".

[0166] The polymerization method for obtaining the 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, a photopolymerization method can be preferably adopted. According to photopolymerization, the polymerization conversion rate of the monomer mixture can be easily controlled by the polymerization conditions such as the amount of light irradiation (light amount).

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

[0168] The adhesive composition containing the partial polymer of the monomer mixture can be easily obtained, for example, by partially polymerizing the monomer mixture containing all of the raw material monomers by an appropriate polymerization method (for example, photopolymerization method). The adhesive composition containing the partial polymer may contain other components (for example, photopolymerization initiator, polyfunctional monomer, crosslinking agent, acrylic oligomer described later, etc.) that are used as necessary. The method of adding such other components is not particularly limited, and for example, they may be contained in the monomer mixture in advance, or may be added to the partial polymer.

[0169] The adhesive composition 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 monomers) is dissolved in the remaining types of monomers or their partial polymers. Such a form of adhesive composition is also included in the examples of adhesive compositions containing polymerized and unpolymerized monomers of the monomer components. In this specification, the term "completely polymerized" refers to a polymerization conversion rate of more than 95% by weight.

[0170] A photopolymerization method can be preferably adopted as a curing method (polymerization method) when forming an adhesive from an adhesive composition containing a polymerized product and an unpolymerized product of a monomer component. In an adhesive composition containing a polymerization reactant prepared by a photopolymerization method, it is particularly preferable to adopt a photopolymerization method as a curing method. Since the polymerization reactant obtained by the photopolymerization method already contains a photopolymerization initiator, when the adhesive composition containing this polymerization reactant is further cured to form an adhesive, it can be photocured without adding a new photopolymerization initiator. Alternatively, the adhesive composition may be a composition in which a photopolymerization initiator is added as necessary to the polymerization reactant prepared by the photopolymerization method. The photopolymerization initiator to be added may be the same as or different from the photopolymerization initiator used in preparing the polymerization reactant. An adhesive composition prepared by a method other than photopolymerization can be made photocurable by adding a photopolymerization initiator. A photocurable adhesive composition has the advantage that even a thick adhesive layer can be easily formed. In some preferred embodiments, photopolymerization when forming an adhesive from the adhesive composition can be performed by ultraviolet irradiation. For the ultraviolet irradiation, a known high pressure mercury lamp, low pressure mercury lamp, metal halide lamp, or the like can be used.

[0171] (Adhesive composition containing monomer component in the form of a completely polymerized product) A PSA composition according to some other embodiments contains a monomer component of the PSA composition in the form of a complete polymer. Such a PSA composition may be in the form of, for example, a solvent-based PSA composition containing an acrylic polymer, which is a complete polymer of the monomer component, in an organic solvent, or a water-dispersed PSA composition in which the acrylic polymer is dispersed in an aqueous solvent.

[0172] (Adhesive layer thickness) 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 suitably 5 μm or more, and may be, for example, 10 μm or more, preferably 20 μm or more, more preferably 25 μm or more, and may be more than 25 μm. When the thickness of the adhesive layer is large, the stress dispersion ability of the adhesive layer tends to be high. This can advantageously contribute to reducing optical distortion. In addition, a thick adhesive layer tends to have excellent step conformability and easily absorbs deformation caused by foreign matter, etc. Impact resistance also tends to be improved. The technology disclosed herein can be preferably 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, when the thickness of the adhesive layer is increased, the optical path passing through the adhesive layer is also increased, so that optical distortion is easily recognized. For this reason, in some embodiments, the thickness of the adhesive layer is suitably set to, for example, 200 μm or less, and may 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 be 35 μm or less. An adhesive layer having such a thickness can be one in which deformation of the adhesive layer is better suppressed. According to the technology disclosed herein, a bond having high deformation resistance and high impact resistance can be formed in a configuration including an adhesive layer having a thickness of, for example, 70 μm or less.

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

[0174] (Tan δ peak top temperature) The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer disclosed herein preferably has a peak top temperature of its loss tangent tan δ in the range of -50°C to 0°C. A pressure-sensitive adhesive having a peak top of tan δ in the low temperature region is likely to provide good impact resistance. The peak top temperature of the loss tangent tan δ of the pressure-sensitive adhesive can be determined by the following method. That is, dynamic viscoelasticity measurement is carried out under the same conditions as the measurement of the 25°C storage modulus described below, and the storage modulus G' and loss modulus G" are measured. The loss tangent tan δ is then calculated by the following formula: tan δ=G" / G'; and the temperature dependency is plotted, whereby the temperature corresponding to the peak top (the temperature at which the tan δ curve is maximum) can be determined.

[0175] (25℃ storage modulus) The storage modulus at 25°C (25°C storage modulus) of the adhesive layer is appropriately set depending on the purpose and mode 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-mentioned 25°C storage modulus is about 4×10 4 It is appropriate to set the pressure to 6×10 Pa or more, and preferably to 6×10 4 Pa or more, more preferably about 8×10 4 Pa or more, approximately 1.0×10 5 Pa or more, and is approximately 1.2×10 5 Pa or more is acceptable, approximately 1.5×10 5 Pa or more is sufficient, approximately 1.8×10 5 The pressure-sensitive adhesive layer having a high storage modulus at 25° C. tends to have excellent resistance to deformation under pressure. 7 Pa or less, approximately 1×10 6 From the viewpoint of suitably exhibiting adhesive properties such as adhesion, the storage modulus at 25° C. is preferably about 5.0×10 Pa or less. 5 Pa or less, more preferably about 3.0×10 5 Pa or less, and more preferably about 2.0×10 5 Pa or less, approximately 1.4×10 5 Pa or less, and may be approximately 1.0×10 5Pa or less. The storage modulus at 25°C of the pressure-sensitive adhesive sheet (typically a substrate-less pressure-sensitive adhesive sheet) is also preferably within the range exemplified above. The storage modulus at 25°C can be adjusted by the molecular weight, molecular structure, concentration, degree of crosslinking, etc. of the base polymer. The storage modulus at 25°C is measured by the following method. The same applies to the examples described below.

[0176] [Storage modulus at 25℃] A pressure-sensitive adhesive layer with a thickness of about 2 mm is prepared by stacking multiple pressure-sensitive adhesive sheets or layers to be measured. A sample is punched out from this pressure-sensitive adhesive layer into a disk shape with a diameter of 7.9 mm, which is sandwiched between parallel plates and fixed. Dynamic viscoelasticity is measured under the following conditions using a viscoelasticity tester (e.g., ARES or equivalent, manufactured by TA Instruments) to determine the storage modulus G' (25°C) [Pa] at 25°C. Measurement mode: Shear mode Temperature range: -70℃~150℃ Heating rate: 5℃ / min ·Measurement frequency: 1Hz

[0177] (Gel fraction) The gel fraction of the adhesive layer is appropriately set according to the purpose of use, the mode of use, etc., and is not limited to a specific range. The gel fraction is, for example, about 99% by weight or less, and is suitably about 97% by weight or less. From the viewpoint of step conformability, etc., in some preferred embodiments, the gel fraction is about 95% by weight or less, more preferably about 92% by weight or less, and may be about 88% by weight or less, may be about 75% by weight or less, or may be about 65% by weight or less. For example, when a logo mark or other print is formed on the surface of the adherend, the adhesive layer having the gel fraction can well conform to the unevenness of the print without impairing visibility. In addition, from the viewpoint of good adhesive properties and viscoelastic properties, the gel fraction of the adhesive layer is, for example, about 10% by weight or more, and is suitably about 20% by weight or more. From the viewpoint of deformation resistance, the gel fraction is preferably about 30% by weight or more, more preferably about 40% by weight, and may be about 50% by weight or more, about 65% by weight or more, or about 75% by weight or more. The gel fraction of the adhesive sheet (typically a substrate-less adhesive sheet) is also preferably 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 below.

[0178] [Gel fraction] A given amount of adhesive sample (weight Wg 1 ) was applied to a porous polytetrafluoroethylene membrane (weight Wg 2 ) into a pouch shape, and the opening is closed with a string (weight Wg 3 As the porous polytetrafluoroethylene (PTFE) membrane, a product name "Nitoflon (registered trademark) NTF1122" (average pore size 0.2 μm, porosity 75%, thickness 85 μm) available from Nitto Denko Corporation or an equivalent product 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 dissolve only the sol component in the adhesive layer outside the film, and then the package is taken out and the ethyl acetate adhering to the outer surface is wiped off. The package is dried at 130° C. for 2 hours, and the weight (Wg 4The gel fraction of the pressure-sensitive adhesive layer is determined by substituting each value into the following formula. Gel fraction (%) = [(Wg 4 -Wg 2 -Wg 3 ) / Wg 1 ] x 100

[0179] The pressure-sensitive adhesive sheets disclosed herein include pressure-sensitive adhesive sheets in a form in which the pressure-sensitive adhesive layer is photocured after being attached to an adherend, and therefore, at least the photocurable pressure-sensitive adhesive sheets (e.g., the pressure-sensitive adhesive sheet of Example 4 having the pressure-sensitive adhesive C described below) are exposed to light with an illuminance of 300 mW / cm 2 , cumulative light intensity 3000mJ / cm 2 The measurement sample is irradiated with ultraviolet light under the conditions of and aged at 50° C. for 48 hours, and then the peak top temperature of tan δ, the storage modulus at 25° C., the gel fraction, the total light transmittance, the haze value, the maximum height Rz of the adhesive surface, the arithmetic mean roughness Ra, the adhesive strength, the modulus of elasticity by a tensile test, and the impact resistance are measured using the measurement sample. When the release film is transparent, the treatment of irradiating with ultraviolet light is preferably performed in a state where the pressure-sensitive adhesive sheet (typically the pressure-sensitive adhesive layer) is sandwiched between transparent release films.

[0180] <Supporting base material> The pressure-sensitive adhesive sheet according to some embodiments may be in the form of a pressure-sensitive adhesive sheet with a support substrate. The material of the support substrate is not particularly limited, and can be appropriately selected according to the purpose and mode of use of the pressure-sensitive adhesive sheet. Non-limiting examples of the support substrate that can be used include resin films such as polyolefin films mainly composed of polyolefins such as polypropylene and ethylene-propylene copolymers, 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 fabrics and nonwoven fabrics made by spinning various fibrous materials alone or in combination; papers such as Japanese paper, fine paper, craft paper, and crepe paper; metal foils such as aluminum foil and copper foil; and the like. The support substrate may be a composite of these. Examples of such a composite structure support substrate include a support substrate having a structure in which a metal layer (e.g., a metal foil, a continuous or discontinuous metal sputter layer, a metal vapor deposition layer, a metal plating layer, etc.) or a metal oxide layer is laminated with the above-mentioned resin film, a resin sheet reinforced with inorganic fibers such as glass cloth, etc. The support substrate may be an optical member (e.g., an optical film) described later, or may be a transparent member formed from a transparent material (e.g., a transparent resin material, glass, etc.).

[0181] As the support substrate of the pressure-sensitive adhesive sheet disclosed herein, various films (hereinafter, also referred to as support films) can be preferably used. The support film may be a porous film such as a foam film or a nonwoven fabric sheet, or may be a nonporous film, or may be a film having a structure in which a porous layer and a nonporous layer are laminated. In some embodiments, the support film may preferably be one that includes a resin film that can independently maintain its shape (self-supporting or independent) as a base film. Here, the term "resin film" refers to a resin film that has a nonporous structure and typically does not substantially contain air bubbles (voidless). Therefore, the resin film is a concept that is distinguished from foam films and nonwoven fabrics. The resin film may be a single-layer structure, or may be a multi-layer structure of two or more layers (for example, a three-layer structure).

[0182] Examples of resin materials constituting the resin film include polyester, polyolefin, polycycloolefin derived from a monomer having an aliphatic ring structure such as a norbornene structure, polyamide (PA) such as nylon 6, nylon 66, and partially aromatic polyamide, polyimide (PI), polyamideimide (PAI), polyetheretherketone (PEEK), polyethersulfone (PES), polyphenylene sulfide (PPS), polycarbonate (PC), polyurethane (PU), ethylene-vinyl acetate copolymer (EVA), polystyrene, fluororesins such as polyvinyl chloride, polyvinylidene chloride, and polytetrafluoroethylene (PTFE), acrylic resins such as polymethyl methacrylate, cellulose-based polymers such as diacetyl cellulose and triacetyl cellulose, vinyl butyral-based polymers, arylate-based polymers, polyoxymethylene-based polymers, and epoxy-based polymers. The resin film may be formed using a resin material containing one of these resins alone, or may be formed using a resin material in which two or more of them are blended. The resin film may be unstretched or stretched (for example, uniaxially or biaxially stretched).

[0183] Suitable examples of resin materials constituting the resin film include polyester-based resin, PPS resin, and polyolefin-based resin. Here, polyester-based resin refers to a resin containing more than 50% by weight of polyester. Similarly, PPS resin refers to a resin containing more than 50% by weight of PPS, and polyolefin-based resin refers to a resin containing more than 50% by weight of polyolefin.

[0184] As the polyester-based resin, typically, a polyester-based resin containing, as a main component, a polyester obtained by polycondensation of a dicarboxylic acid and a diol is used. Specific examples of the polyester-based resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate, etc.

[0185] As the polyolefin resin, one type of polyolefin can be used alone, or two or more types of polyolefins can be used in combination. The polyolefin can be, for example, a homopolymer of an α-olefin, a copolymer of two or more types of α-olefins, or a copolymer of one or more types of α-olefins and other vinyl monomers. Specific examples include polyethylene (PE), polypropylene (PP), poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene copolymers such as ethylene-propylene rubber (EPR), ethylene-propylene-butene copolymers, ethylene-butene copolymers, ethylene-vinyl alcohol copolymers, and ethylene-ethyl acrylate copolymers. Both low density (LD) polyolefins and high density (HD) polyolefins can be used. Examples of polyolefin resin films include non-oriented 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 the support substrate include PET film, PEN film, PPS film, PEEK film, CPP film, and OPP film. Preferred examples from the viewpoint of strength include PET film, PEN film, PPS film, and PEEK film. Preferred examples from the viewpoint of availability, dimensional stability, optical properties, etc. include PET film.

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

[0188] The method for producing the resin film is not particularly limited, and may be any of the conventionally known general resin film forming methods such as extrusion molding, inflation molding, T-die casting, and calendar roll molding.

[0189] The support substrate may be a support film substantially composed of such a resin film. The support substrate may also be a support film including an auxiliary layer in addition to the resin film. The auxiliary layer may be disposed on the adhesive layer side of the resin film, on the opposite side to the adhesive layer, or on both sides of the resin film. Examples of the auxiliary layer include an optical property adjusting layer (e.g., a colored layer, an anti-reflection layer), a decorative layer (e.g., a printed layer, a laminate layer, a continuous or discontinuous metal layer, a continuous or discontinuous metal oxide layer, etc.) that imparts a desired appearance to the support substrate or the adhesive sheet, a conductive layer, an antistatic layer, an undercoat layer, a peeling layer, etc.

[0190] In some embodiments, the supporting substrate is preferably a transparent plastic film. In this embodiment, the total light transmittance of the supporting substrate is, for example, about 50% or more, and is preferably, for example, about 70% or more. From the viewpoint of visibility of the adherend through the pressure-sensitive adhesive sheet, in some preferred embodiments, the total light transmittance of the supporting substrate is about 85% or more, more preferably about 90% or more. The upper limit of the total light transmittance may be, in practical terms, about 95% or less, or about 94% or less (for example, 93% or less). The total light transmittance of the supporting substrate can be measured using a haze meter, such as "HM-150N" manufactured by Murakami Color Research Laboratory or an equivalent product.

[0191] The thickness of the support substrate is not particularly limited and may be selected according to the purpose and mode of use of the pressure-sensitive adhesive sheet. The thickness of the support substrate may be, for example, 1000 μm or less, and from the viewpoint of handleability (e.g., ease of rolling), etc., it is appropriate to be 500 μm or less, and preferably 300 μm or less, and may 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. When the thickness of the support substrate is reduced, the flexibility of the pressure-sensitive adhesive sheet and its ability to follow the surface shape of the adherend tend to improve. In addition, from the viewpoint of handleability, processability, etc., the thickness of the support substrate may be, for example, 2 μm or more, or may be more than 5 μm or more 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 to be bonded to the pressure-sensitive adhesive layer may be subjected to a conventionally known surface treatment such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, application of an undercoat (primer), antistatic treatment, etc., as necessary. Such a surface treatment may be a treatment for improving the adhesion between the support substrate and the pressure-sensitive adhesive layer, in other words, the anchoring property of the pressure-sensitive adhesive layer to the support substrate. The composition of the primer is not particularly limited and can be appropriately selected from known ones. The thickness of the undercoat layer is not particularly limited, but is appropriately about 0.01 μm to 1 μm, and preferably about 0.1 μm to 1 μm.

[0193] <Method of manufacturing adhesive sheet with release film> The method for producing the adhesive sheet with a release film disclosed herein is not particularly limited. For example, an adhesive composition is applied to the release surface of a release film, and dried (e.g., dried by heating) or cured to form an adhesive layer on the release surface, and a different release film is laminated on the surface of the adhesive layer opposite to the release surface, thereby obtaining an adhesive sheet with a release film. Alternatively, an adhesive sheet with a release film may be formed by drying or curing an adhesive composition sandwiched between two release films to form an adhesive layer. For an adhesive sheet having a support substrate, for example, a method (direct method) can be adopted in which an adhesive composition is applied to the support substrate and dried or cured to form an adhesive layer. In addition, a method (transfer method) can be adopted in which an adhesive composition is applied to a surface (release surface) having releasability, and dried to form an adhesive layer on the surface, and the adhesive layer is transferred to a support substrate.

[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 types of curing treatment are performed, they can be performed simultaneously or stepwise. As a method for applying the pressure-sensitive adhesive composition, various conventionally known methods can be used. Specific 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, extrusion coating using a die coater, etc.

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

[0196] The adhesive sheet with a release film disclosed herein can be preferably manufactured by a method including curing the liquid film of the adhesive composition between the release surfaces of the first release film and the second release film to form an adhesive layer. As a method for disposing the liquid film of the adhesive composition between the release surfaces of the first release film and the second release film, a method can be adopted in which the liquid adhesive composition is applied to the release surface of one release film, and then the liquid film of the adhesive composition is covered with the other release film. As another method, a method can be mentioned in which the first release film and the second release film are supplied between a pair of rolls with their release surfaces facing each other, and the liquid adhesive composition is supplied between the release surfaces. The adhesive composition is preferably applied at 80° C. or less, more preferably at 60° C. or less (for example, 40° C. or less). This suppresses roughness of the adhesive layer due to the difference in thermal expansion coefficient between the first release film, the second release film, and the adhesive layer, and a more smooth adhesive surface can be formed.

[0197] The total thickness of the adhesive sheet with a 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 a release film refers to the total thickness of the adhesive sheet with a release film consisting 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 a 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 a release film may be, for example, 1000 μm or less, 500 μm or less, or 300 μm or less.

[0198] <Roll body> According to this specification, a roll body (adhesive sheet roll with release film) is provided that includes the adhesive sheet with release film disclosed herein in a wound form. Such a roll body typically includes a core (winding core) and an adhesive sheet with release film wound around the core. The shape of the core is not particularly limited, and may be, for example, a solid columnar shape, a hollow columnar shape (i.e., a cylindrical shape), a hollow or solid polygonal columnar shape, etc. From the viewpoint of improving the handleability of the roll body, a hollow columnar or hollow polygonal columnar core may be preferably used. A cylindrical core is particularly preferred.

[0199] <Attachment to the substrate> The method of attaching the adhesive sheet disclosed herein to an adherend is not particularly limited. Any known or conventional pressure-bonding method can be adopted according to the purpose and mode of use. In some preferred modes, the adhesive sheet can be used in a mode in which the adhesive sheet is attached to the adherend by a method including photocuring the adhesive layer after the sheet is attached to the adherend. By attaching the adhesive sheet to the adherend, an adherend on which the adhesive sheet is laminated is formed. By photocuring the adhesive layer of the adhesive sheet, a laminate including the adhesive sheet with the cured adhesive layer and the adherend is obtained. Thus, this specification provides a method of attaching an adhesive sheet, which includes, in this order, attaching any one of the adhesive sheets disclosed herein to an adherend and irradiating the adhesive sheet with ultraviolet light to photocuring the adhesive layer.

[0200] <Application> The pressure-sensitive adhesive sheet disclosed herein can be used for fixing, joining, forming, decorating, protecting, supporting, and the like of components constituting various products. The material constituting at least the surface of the above-mentioned component can be, for example, glass such as alkali glass or non-alkali glass; metal materials such as stainless steel (SUS) and aluminum; resin materials such as acrylic resin, ABS resin, polycarbonate resin, polyimide resin, polyester resin such as PET, polystyrene resin, and the like. The above-mentioned component can be, for example, a component constituting various mobile devices (portable devices), automobiles, home appliances, and the like. In addition, the surface of the above-mentioned component to which the pressure-sensitive adhesive sheet is attached can be a painted surface with a paint such as an acrylic-based, polyester-based, alkyd-based, melamine-based, urethane-based, acid-epoxy crosslinked, or a composite of these (for example, an acrylic-melamine-based, alkyd-melamine-based) paint, or a plated surface such as a zinc-plated steel sheet. In addition, the above-mentioned component can be, for example, a resin film, or a resin film having a continuous or discontinuous inorganic layer (which can be a metal layer, a metal oxide layer, and the like).

[0201] An 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 used for bonding optical members (for bonding optical members) or for manufacturing products (optical products) using the optical members.

[0202] The optical member refers to a member having optical properties (for example, polarizing, light refraction, light diffraction, optical rotation, etc.). The optical member is not particularly limited as long as it has optical properties, but examples thereof include members constituting devices (optical devices) such as display devices (image display devices) and input devices, or members used in these devices, such as polarizing plates, wave plates, retardation plates, optical compensation films, brightness improvement films, light guide plates, reflective films, anti-reflection films, hard coat (HC) films, impact absorbing films, antifouling films, photochromic films, light control films, transparent conductive films (ITO films), and further members in which these are laminated (these may be collectively referred to as "functional films"). The above "plate" and "film" are intended to include plate-like, film-like, sheet-like, and other forms, and for example, "polarizing film" is intended to include "polarizing plate", "polarizing sheet", and the like.

[0203] Examples of the display device include a liquid crystal display device, an organic EL (electroluminescence) display device, a PDP (plasma display panel), electronic paper, etc. Examples of the input device include a touch panel, etc.

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

[0205] The embodiment of bonding an optical member using the adhesive sheet disclosed herein is not particularly limited, and may be, for example, (1) an embodiment in which optical members are bonded to each other via the adhesive sheet disclosed herein, (2) an embodiment in which an optical member is bonded to a member other than an optical member via the adhesive sheet disclosed herein, or (3) an embodiment 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 above embodiment (3), the adhesive sheet having an optical member may be, for example, an adhesive sheet whose supporting substrate is an optical member (e.g., an optical film). In this way, an adhesive sheet having an optical member as a supporting substrate may also be understood as an adhesive-type optical member (e.g., an adhesive-type optical film). In addition, when the adhesive sheet disclosed herein is an adhesive sheet having a supporting substrate and the functional film is used as the supporting substrate, the adhesive sheet disclosed herein may also be understood as an "adhesive-type functional film" having an adhesive layer disclosed herein on at least one side of the functional film.

[0206] The adhesive sheet disclosed herein can be preferably used for applications in which it is attached to a decorative film. Here, the decorative film refers to a film having a design (including color, tone, pattern, and even text information such as a logo mark. The same applies below) on its surface (decorated surface), and is also called a design film or a decorative film. The decorative film includes a member that plays a role in decoration and protection while maintaining the visibility of an image display device or an input device. Examples of the decorative film include a film having a decorative layer (printed layer, laminate layer, colored layer, glossy layer, continuous or discontinuous inorganic layer (metal layer, metal oxide layer, etc.) that imparts a desired appearance. The decorative film can have a design on its surface and exhibit good concealment properties.

[0207] The decorative film may have a decorative layer. Examples of the decorative layer include a print layer, a laminate layer, a colored layer, a glossy layer, a continuous or discontinuous inorganic layer, etc., which impart a desired appearance. Examples of the continuous or discontinuous inorganic layer 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 alloys thereof. Examples of the metal oxide include chromium oxide, indium oxide, zinc oxide, titanium oxide, etc. The metal layer or metal oxide layer can be formed by deposition, sputtering, or the like. A typical example of a decorative film is a metallic film. A metallic decorative film may have electromagnetic wave transparency in addition to metallic luster. Examples of such decorative films include electromagnetic wave-transmitting metallic glossy members as described in JP-A-2018-69462, JP-A-2019-123238, and JP-A-2019-188805.

[0208] The decorative film may further include a substrate layer and a decorative layer covering at least a part of at least one surface of the substrate layer. As the substrate layer, various resin films such as the above-mentioned plastic films may be used. Among them, resin films formed from polyester resins such as PET, polyolefin resins, polycarbonate resins, and (meth)acrylic resins are preferred. The thickness of the substrate layer is not particularly limited, and is, for example, about 5 to 250 μm. The decorative layer may be disposed on the adhesive sheet side of the substrate layer, on the opposite side to the adhesive sheet side, or on both sides of the substrate layer.

[0209] In a decorative film including a decorative layer, the thickness of the decorative layer is preferably within the range of about 1 to 1000 nm, and may be, for example, about 1 to 300 nm, or may be, for example, about 1 to 200 nm. The sheet resistance of the decorative layer is suitably 100 Ω / □ or more, and may be, for example, 250 Ω / □ or more, or may be 1000 Ω / □ or more. A decorative film having such a decorative layer can have radio wave transparency, and can be preferably used in various applications requiring radio wave transparency, such as portable electronic devices. The upper limit of the sheet resistance of the decorative layer is not particularly limited, and may be, for example, 1×10 16 The sheet resistance can be measured based on the eddy current measurement method described in JIS Z 2316.

[0210] The design-forming surface of the decorative film may be flat or may have irregularities due to a printed matter such as a logo mark, an engraved mark, etc. The pressure-sensitive adhesive sheet disclosed herein may have excellent step conformability, and therefore can adhere well to the decorative film surface having the irregularities.

[0211] In addition, the adhesive sheet disclosed herein can have excellent visibility of the adherend based on the high surface smoothness, and therefore can be preferably used for applications in which the sheet is attached to a transparent member or for fixing two members, at least one of which is a transparent member. Examples of such member fixing applications include an embodiment in which one member is a transparent member and the other is a member having an image display surface, a decorative surface, or a colored surface. In other words, the adhesive sheet disclosed herein is preferably used for fixing a member having an image display surface, a decorative surface, or a colored surface to a transparent member. Examples of the image display surface include the above-mentioned liquid crystal display surface, organic EL display surface, PDP, electronic paper, etc. Examples of the decorative surface include the decorative surface of the above-mentioned decorative film. Examples of the colored surface include the surface of a light-shielding film or a concealing film. Examples of the transparent member include glass, or a member formed from a transparent material made of a resin such as an acrylic resin, polycarbonate, or PET. In such a configuration, for example, by using an adhesive sheet having a total light transmittance or haze value of a predetermined value or more, the image display surface, decorative surface, or colored surface of the adherend member can be well viewed through the adhesive sheet and the transparent member.

[0212] The transparent member may be flat, but the adhesive sheet attachment surface may have unevenness such as printing or engraving, or the transparent member may have a three-dimensional shape as a whole. The adhesive sheet disclosed herein may have excellent step-following properties, so it can adhere well to the uneven transparent member surface. In addition, the transparent member having a three-dimensional shape may have a bent portion that is bent linearly or a curved portion that is curved curved in a curved line in a cross section in the thickness direction. The transparent member may have a shape in which the adhesive sheet attachment surface is bent or curved in any one direction, or may have a shape in which the adhesive sheet attachment surface is bent or curved in two directions that intersect (for example, perpendicular to) the one direction in addition to the one direction. In other words, the adhesive sheet attachment 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 a portable electronic device. In the portable electronic device, the adhesive sheet can be preferably used for application to be attached to a transparent member or for application to fix a member at least one of which is a transparent member. In the portable electronic device, the adhesive sheet can be preferably used for application to be attached to an image display surface, a decorative surface, or a colored surface. For example, the adhesive sheet disclosed herein can be preferably used for application to fix an image display surface, a decorative surface, or a colored surface of a component member (e.g., a decorative film) to the inside of a transparent housing as a transparent member. According to such a configuration, while the decorative surface can be visually recognized from the outside of the housing, for example, in an embodiment using a member having a colored surface, it can have an internal concealment property, and therefore can be particularly suitable as an exterior structure such as a case.

[0214] Non-limiting examples of the portable electronic devices include mobile phones, smartphones, tablet computers, notebook computers, various wearable devices (for example, wristwear-type devices worn on the wrist like a wristwatch, modular-type devices worn on a part of the body with a clip or strap, eyewear-type devices including glasses-type devices (monocular and binocular types, including head-mounted types), clothing-type devices attached to shirts, socks, hats, etc. in the form of accessories, earwear-type devices attached to the ears like earphones, etc.), digital cameras, digital video cameras, audio devices (portable music players, IC recorders, etc.), calculators (calculators, etc.), portable game devices, electronic dictionaries, electronic organizers, electronic books, in-vehicle information devices, portable radios, portable televisions, portable printers, portable scanners, portable modems, etc. In this specification, "portable" does not mean that it is sufficient to simply be portable, but rather that it has a level of portability that allows an individual (average adult) to carry it relatively easily.

[0215] The matters disclosed in this specification include the following. [1] A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer and a release film laminated on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet, A pressure-sensitive adhesive sheet with a release film, wherein the maximum height Rz of the adhesive surface of the release film is 400 nm or less. [2] The pressure-sensitive adhesive sheet with a release film according to the above-mentioned [1], wherein the arithmetic mean roughness Ra of the adhesive surface of the release film is 30 nm or less. [3] The adhesive sheet with a release film according to the above [1] or [2], wherein the peeling strength of the release film from the adhesive sheet is 1 N / 50 mm or less. [4] The pressure-sensitive adhesive sheet with a release film according to any one of the above [1] to [3], wherein the release film has a thickness in the range of 50 to 125 μm. [5] The pressure-sensitive adhesive sheet with a release film according to any one of the above [1] to [4], wherein the pressure-sensitive adhesive sheet has a total light transmittance of 85% or more and a haze value of 1% or less. [6] The pressure-sensitive adhesive sheet with a release film according to any one of the above-mentioned [1] to [5], wherein the pressure-sensitive adhesive sheet is a single-sided pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer and a supporting substrate laminated on one side of the pressure-sensitive adhesive layer. [7] The pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet having a first adhesive surface and a second adhesive surface, The release film includes a first release film disposed on the first adhesive surface and a second release film disposed on the second adhesive surface, The maximum height Rz of the first adhesive surface S1 of the first release film 1 and the maximum height Rz of the second adhesive surface S2 of the second release film 2 The pressure-sensitive adhesive sheet with a release film according to any one of the above [1] to [5], wherein each of the thicknesses is 400 nm or less. [8] The pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet having a first pressure-sensitive adhesive surface and a second pressure-sensitive adhesive surface, The release film is a double-sided release film having a first release surface and a second release surface, The maximum height Rz of the first release surface of the release film 1 and the maximum height Rz of the second release surface of the release film 2 The pressure-sensitive adhesive sheet with a release film according to any one of the above [1] to [5], wherein each of the thicknesses is 400 nm or less. [9] The pressure-sensitive adhesive sheet with a release film according to any one of the above [1] to [8], wherein the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer.

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

[11] The pressure-sensitive adhesive sheet has a storage modulus of 4×10 at 25° C. 4 The pressure-sensitive adhesive sheet with a release film according to any one of the above [1] to

[10] , having a compressive strength of at least 1 Pa.

[12] The pressure-sensitive adhesive sheet with a release film according to any one of the above [1] to

[11] , wherein the pressure-sensitive adhesive sheet has a thickness of 5 to 100 μm.

[13] The pressure-sensitive adhesive sheet with a release film according to any one of the above [1] to

[12] , wherein the pressure-sensitive adhesive sheet has a modulus of elasticity of 3.0 MPa or more as measured by the following tensile test. [Tensile test] The adhesive layer of the adhesive sheet is exposed to an illuminance of 300 mW / cm 2 , cumulative light intensity 3000mJ / cm 2 After aging at 50° C. for 48 hours, the pressure-sensitive adhesive layer is cut to a size of 10 mm in width and 150 mm in length to prepare a test piece. A tensile test is performed on the test piece using a tensile tester under conditions of 23° C., 50% RH, 120 mm between-chuck distance, and 50 mm / min tensile speed to obtain a stress-displacement curve, and the elastic modulus [MPa] is calculated from the initial slope.

[14] The pressure-sensitive adhesive sheet has an impact resistance of 2.0 J / 10 mm as measured by the following shear impact test. 2 The pressure-sensitive adhesive sheet with a release film according to any one of the above items [1] to

[13] . [Shear impact test] A shear impact test is performed using a pendulum type adhesive shear impact tester based on JIS K6855. As a measurement sample, the first surface of the 10 mm square adhesive sheet is attached to the center of a 25 mm square, 1.7 mm thick chemically strengthened glass plate, and then the second surface of the adhesive sheet is 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, then autoclaved (50°C, 0.5 MPa, 15 minutes), and the illuminance from the glass plate side is 300 mW / cm. 2 , cumulative light intensity 3000mJ / cm 2 After irradiating ultraviolet light under the above conditions, the film is aged at 50°C for 48 hours before use. The measurement sample was fixed so that the stainless steel plate was on the bottom side, and a hammer was applied to the outer peripheral side of the glass plate at a hammer energy of 2.75 J and a hammer speed of 3.5 m / sec in an environment of 23°C and 50% RH. The absorbed energy [J] was measured to determine the impact resistance [J / 10 mm 2 ] is required.

[15] The pressure-sensitive adhesive sheet with a release film according to any one of the above [1] to

[14] , wherein the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet contains a polymer (A) and a photoreactive monomer (B).

[16] The pressure-sensitive adhesive sheet with a release film according to the above-mentioned

[15] , wherein the photoreactive monomer (B) comprises a compound B1 having a ring structure and two or more ethylenically unsaturated groups in the molecule, and the compound B1 has a molecular weight per one of the ethylenically unsaturated groups of 100 g / mol or more.

[0216]

[17] The pressure-sensitive adhesive sheet with a release film according to the above-mentioned

[16] , wherein the 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.

[18] The pressure-sensitive adhesive sheet with a release film according to the above

[16] or

[17] , wherein the compound B1 contains an aliphatic ring structure as the ring structure.

[19] The pressure-sensitive adhesive sheet with a release film according to any one of

[16] to

[18] above, wherein the compound B1 contains, in the molecule, at least one structure selected from the group consisting of a hydroxyl group and an amino group.

[20] The pressure-sensitive adhesive sheet with a release film according to any one of

[16] to

[19] above, wherein the content of the compound B1 in the pressure-sensitive adhesive layer is 0.5 parts by weight or more and 60 parts by weight or less per 100 parts by weight of the polymer (A).

[21] The pressure-sensitive adhesive sheet with a release film according to any one of

[16] to

[20] above, wherein the pressure-sensitive adhesive layer contains, as the photoreactive monomer (B), the compound B1 and a compound B2 having two or more functional groups and not having a ring structure in the molecule.

[22] The pressure-sensitive adhesive sheet with a release film according to the above-mentioned

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

[23] The pressure-sensitive adhesive sheet with a release film according to the above

[21] or

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

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

[21] to

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

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

[15] to

[24] above, wherein the content of the photoreactive monomer (B) in the pressure-sensitive 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 pressure-sensitive adhesive sheet with a release film according to any one of the above

[15] to

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

[27] The pressure-sensitive adhesive sheet with a release film according to the above-mentioned

[26] , wherein the monomer component constituting the acrylic polymer includes a monomer having a nitrogen atom-containing ring.

[28] The pressure-sensitive adhesive sheet with a release film according to any one of the above

[15] to

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

[29] The pressure-sensitive adhesive sheet with a release film according to any one of the above

[15] to

[28] , wherein the pressure-sensitive adhesive layer is crosslinked with a crosslinking agent.

[30] The pressure-sensitive adhesive sheet with a release film according to any one of

[15] to

[29] above, wherein the pressure-sensitive adhesive layer contains a photopolymerization initiator.

[31] The pressure-sensitive adhesive sheet with a release film according to any one of the above

[15] to

[30] , wherein the pressure-sensitive adhesive layer contains a silane coupling agent.

[32] The pressure-sensitive adhesive sheet with a release film according to any one of the above [1] to

[31] , wherein the pressure-sensitive adhesive sheet has an adhesive strength to glass of 1.0 N / 20 mm or more.

[0217]

[33] The pressure-sensitive adhesive sheet with a release film according to any one of the above [1] to

[32] , which is used for fixing a member having an image display surface, a decorative surface or a colored surface to a transparent member.

[34] A roll of an adhesive sheet with a release film, comprising the adhesive sheet with a release film according to any one of [1] to

[33] above wound thereon.

[0218] Some examples of the present invention will be described below, but it is not intended that the present invention be limited to those shown in the examples. In the following description, "parts" and "%" are by weight unless otherwise specified.

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

[0220] [Adhesion to glass] The adhesive sheet with release film is cut to a length of 100 mm and a width of 20 mm. Next, one of the release films of the adhesive sheet with release film is peeled off, and a PET film (trade name "Lumirror S-10", manufactured by Toray Industries, Inc., thickness 25 μm) is backed up. Next, the release film on the other side (measurement surface side) is peeled off, and a 2 kg roller is rolled back and forth once to press the glass plate (trade name "Soda Lime Glass #0050", manufactured by Matsunami Glass Industry Co., Ltd.) as a test plate, to prepare a test piece consisting of test plate / adhesive sheet / PET film. The obtained test piece is autoclaved (50°C, 0.5 MPa, 15 minutes), and then allowed to cool for 30 minutes under an atmosphere of 23°C and 50% RH. After cooling, the adhesive sheet (measurement surface side) is peeled off from the test plate using a tensile tester (machine name "Autograph AG-IS", manufactured by Shimadzu Corporation) in accordance with JIS Z 0237 under conditions of 23°C, 50% RH, tensile speed 300 mm / min, and peel angle 180°. This is the adhesion strength to glass [N / 20 mm]. In the case of a pressure-sensitive adhesive sheet protected by a release film having release surfaces on both sides, or in the case of a one-sided adhesive sheet, it is not necessary to peel off one of the release films or to back it with a PET film.

[0221] [Release film peel strength] The adhesive sheet with release film is cut to a length of 150 mm and a width of 50 mm, fixed to a test plate, and the release film on the light release side is peeled off from the adhesive sheet using a tensile tester (Autograph AG-IS, manufactured by Shimadzu Corporation) under conditions of 23°C, 50% RH, a tensile speed of 300 mm / min, and a peel angle of 180°. The maximum value in the following 50 mm section, excluding the section 30 mm from the start of peeling, is the release film peel force (light release side) [N / 50 mm]. The peeling force of the release film on the heavy release side is measured by peeling off the release film on the light release side that protects the adhesive sheet with the release film, backing it with a PET film (trade name "Lumirror S-10", manufactured by Toray Industries, Inc., thickness 25 μm), fixing the PET film side to a test plate, and using a tensile tester (device name "Autograph AG-IS", manufactured by Shimadzu Corporation) under conditions of 23 ° C, 50% RH atmosphere, tensile speed 300 mm / min, and peel angle 180 °, peeling the release film on the heavy release side from the adhesive sheet. The maximum value in the following 50 mm section, excluding the section 30 mm from the start of peeling, is the release film peeling force (heavy release side) [N / 50 mm]. In the case of an adhesive sheet protected by a release film with release surfaces on both sides, or in the case of a single-sided adhesive sheet, it is sufficient to carry out the measurement of the peel force of one of the release surfaces in the same manner as the measurement of the release force of the release film on the light release side described above, and no backing with a PET film is required.

[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-mentioned conditions for measuring the peel strength of the release film, the release film is peeled off from the adhesive sheet with release film at a peel angle of 180° at a speed of 300 mm / min, and the exposed adhesive surface is left to stand for 30 minutes, and the surface shape is measured using a three-dimensional optical profiler (product name "NewView7300", manufactured by ZYGO Corporation) 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 calculated as the sum of the height Rp of the highest peak above the mean line of the roughness curve and the depth Rv of the deepest valley below the mean line of the data (roughness curve) obtained by the above measurement. The measurement conditions are as follows. The measurements of Ra and Rz are carried out five times (i.e., N=5), and the 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 (2 mm thick) made of plain glass by silver coating is prepared, and the mirror is used after visual inspection and projecting a reflected image onto a screen using the same method as described below to confirm that there is no distortion. In a clean room, the surface of the mirror is cleaned with a clean cloth, and then one of the release films of the adhesive sheet with release film is peeled off from the adhesive sheet and attached to the surface of the mirror with an appropriate tension so that no foreign matter, air bubbles, or deformation lines are introduced, and a degassing process is performed using a pressurized degassing device (autoclave) to remove the influence of minute air bubbles (processing conditions: 50°C, 0.5 MPa, 15 minutes). After cooling at room temperature for 30 minutes or more, the other 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 placed so that the adhesive sheet side faces the point light source and the angle with respect to the light from the point light source is about 45 degrees. A white screen is placed at the end of the light beam to reflect the reflected image. The point light source may be a product named "Xenon Lamp C2577" manufactured by Hamamatsu Photonics KK or an equivalent product. The point light source, evaluation sample, and screen are 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 each approximately 50 cm. The point light source is turned on, and the image reflected by the sample and projected onto the screen is visually observed to evaluate the presence and degree of optical distortion according to the following three levels. E: No optical distortion is observed. A: Some optical distortion is observed, but is within the range of acceptable practical use. P: Obvious optical distortion is observed.

[0224] [Elastic modulus by tensile test] A test specimen was prepared by cutting an adhesive sheet (adhesive layer) with a release film to a size of 10 mm wide and 150 mm long. In an environment of 23°C and 50% RH, two release films were peeled off to expose the adhesive layer. A tensile test was then performed on the test specimen using a tensile testing machine (machine name "Autograph AG-IS", manufactured by Shimadzu Corporation) with a chuck distance of 120 mm and a tensile speed of 50 mm / min to obtain an SS curve, and the elastic modulus [MPa] was calculated from the initial slope (the elastic deformation region of the SS curve, specifically the slope in the range where the displacement is less than approximately 5%).

[0225] The thickness of the test piece used in the tensile test may be the same as or different from the thickness of the adhesive sheet (typically the adhesive layer) as described above. For example, when the thickness of the adhesive sheet is relatively small, the result obtained by carrying out the tensile test using a test piece prepared to have a thickness of 5 μm or more (for example, about 5 μm to 200 μm) for the purpose of improving operability, etc., can be adopted as the elastic modulus of the adhesive sheet. For example, the thickness of the test piece can be adjusted by appropriately overlapping the adhesive layer before ultraviolet irradiation in the case of a photocurable adhesive sheet. In addition, a test piece having a thickness that is easy to carry out a tensile test is prepared using the same adhesive composition as that used to form the adhesive layer to be measured, and the result obtained by carrying out the tensile test on the test piece can be adopted as the elastic modulus of the adhesive layer. The tensile test can be carried out, for example, using a test piece having a thickness of about 10 μm to 50 μm (preferably, about 15 μm to 25 μm).

[0226] [Impact resistance] A shear impact test is performed using a pendulum-type adhesive shear impact tester based on JIS K 6855. As a measurement sample, an adhesive sheet with a release film is cut into 10 mm squares, one release film is peeled off to expose a first adhesive surface of the adhesive sheet, and the first adhesive surface is attached to the center of a 25 mm square, 1.7 mm thick chemically strengthened glass plate (manufactured by Corning), the other release film is peeled off to expose a second adhesive surface of the adhesive sheet, and the second adhesive surface is 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, then autoclaved (50°C, 0.5 MPa, 15 minutes), and an illuminance of 300 mW / cm is applied from the glass plate side using a high-pressure mercury lamp. 2 , cumulative light intensity 3000mJ / cm 2 After irradiating ultraviolet light under the above conditions, the film is aged at 50°C for 48 hours before use. The measurement sample was fixed so that the stainless steel plate was on the bottom, and the impact resistance [J / 10 mm] was measured by measuring the absorbed energy [J] when a hammer hit the outer peripheral side of the glass plate under conditions of a hammer energy of 2.75 J and a hammer speed (impact speed) of 3.5 m / s in an environment of 23°C and 50% RH. 2 The measurement is carried out three times, and the arithmetic mean value is used. In the case of a pressure-sensitive adhesive sheet protected by a release film having release surfaces on both sides, the measurement can be carried out in the same manner as above, except that only one release film is peeled off.

[0227] The pressure-sensitive adhesive sheets disclosed herein include pressure-sensitive adhesive sheets in a form in which the pressure-sensitive adhesive layer is photocured after being attached to an adherend, and therefore, at least the photocurable pressure-sensitive adhesive sheets (e.g., the pressure-sensitive adhesive sheet of Example 4 having the pressure-sensitive adhesive C described below) are exposed to light with an illuminance of 300 mW / cm 2 , cumulative light intensity 3000mJ / 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, elastic modulus by tensile test) are carried out using a measurement sample after aging at 50 ° C for 48 hours. Regarding adhesion to glass, the photocurable adhesive sheet (for example, the adhesive sheet of Example 4 having adhesive C described later) is pressed onto a test plate, and then the measurement is carried out by irradiating ultraviolet rays under the above conditions. In addition, when the release film is transparent, the treatment of irradiating ultraviolet rays is preferably carried out in a state where the adhesive sheet (typically the adhesive layer) is sandwiched between transparent release films. It is advisable to measure the illuminance and light intensity of the light source using an industrial UV checker (model "UVR-T2", light receiving part "UD-T36T2", manufactured by TOPCON) by adjusting the actual distance between the light source and the sample.

[0228] <Example 1> (Preparation of Pressure-Sensitive Adhesive Composition) After mixing 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, 0.075 parts of "Irgacure 651" (BASF) and 0.075 parts of "Irgacure 184" (BASF) as photopolymerization initiators, this monomer mixture was exposed to ultraviolet light under a nitrogen atmosphere to partially photopolymerize, thereby obtaining a partially polymerized product (acrylic polymer syrup) with a polymerization rate of about 10%. 0.14 parts of dipentaerythritol hexaacrylate (trade name "KAYARAD DPHA", Nippon Kayaku Co., Ltd.) and 0.3 parts of a silane coupling agent (trade name "KBM-403", Shin-Etsu Chemical Co., Ltd.) were added to 100 parts of the obtained acrylic polymer syrup and mixed uniformly to obtain an acrylic adhesive composition A.

[0229] (Preparation of adhesive sheet) As the first release film, a PET release film having a thickness of 75 μm and a first adhesive surface S1, which is the surface to be laminated on the first adhesive surface of the adhesive sheet, being a release surface made of a silicone-based release treatment agent, and surface S1 having an Ra of 18 nm and an Rz of 223 nm, was prepared. As the second release film, a PET release film having a thickness of 100 μm and a second adhesive surface S2, which is the surface to be laminated on the second adhesive surface of the adhesive sheet, being a release surface made of a silicone-based release treatment agent, and surface S2 having an Ra of 18 nm and an Rz of 223 nm, was prepared. The acrylic adhesive composition A obtained above was applied onto the first adhesive surface S1 of the first release film so that the thickness after the adhesive layer was formed would be 100 μm to form an adhesive composition layer, and then the surface of the adhesive composition layer was covered with the second release film so that the second adhesive surface S2 was on the adhesive composition layer side. This blocked the adhesive composition layer from oxygen. Thereafter, the adhesive composition layer was exposed to light at an illuminance of 5 mW / cm 2 , light intensity 2000mJ / cm 2 The pressure-sensitive adhesive composition layer was photocured by irradiating with ultraviolet light under the above conditions to produce a substrate-less double-sided pressure-sensitive adhesive sheet consisting of only an acrylic pressure-sensitive adhesive layer (also referred to as pressure-sensitive adhesive A), each side of which was protected by a first and second release film. The weight-average molecular weight (Mw) of the acrylic polymer serving as the base polymer of the pressure-sensitive adhesive layer was 2,000,000.

[0230] <Example 2> The first and second release films used were release films having surfaces S1 and S2 with Ra and Rz shown in Table 1. The thickness of the adhesive layer was changed to 25 μm. Otherwise, the substrate-less double-sided adhesive sheet according to this example was produced 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 above, 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, and an acrylic pressure-sensitive adhesive composition B was obtained in the same manner as in Example 1 above, except that the obtained acrylic pressure-sensitive adhesive composition B was used and the thickness of the pressure-sensitive adhesive layer (also referred to as pressure-sensitive adhesive B) was 50 μm, and a substrate-less double-sided pressure-sensitive adhesive sheet according to this example was produced in the same manner as in Example 2 above.

[0232] <Example 4> (Preparation of Pressure-Sensitive Adhesive Composition) In a reaction vessel equipped with a cooling tube, nitrogen introduction tube, thermometer and stirrer, 60 parts of BA, 6 parts of CHA, 18 parts of NVP, 1 part of isostearyl acrylate (iSTA) and 15 parts of 4HBA as monomer components, 0.085 parts of α-thioglycerol as a chain transfer agent, 0.2 parts of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator, and ethyl acetate as a polymerization solvent were added so that the monomer components were 45%, and nitrogen gas was flowed and nitrogen replacement was performed for about 1 hour while stirring. After that, 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 on a solids basis of trimethylolpropane / xylylene diisocyanate adduct (manufactured by Mitsui Chemicals, Inc., product name "Takenate D-110N", solids concentration 75%) as an isocyanate crosslinking agent, 0.01 parts of dioctyltin dilaurate (manufactured by Tokyo Fine Chemicals, product name "Envirizer OL-1") as a crosslinking accelerator, 4 parts of acetylacetone as a crosslinking retarder, 0.3 parts of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-403") as a silane coupling agent, 8 parts of dipentaerythritol hexaacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-DPH") and 12 parts of tricyclodecane dimethanol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-DCP") as photoreactive monomers, and 1-hydroxycyclohexyl-phenyl-ketone (IGM) as a photopolymerization initiator were added. 0.7 parts of "Omnirad184" (manufactured by Regins) was added and mixed uniformly to prepare a pressure-sensitive adhesive composition C according to this example.

[0233] (Preparation of adhesive sheet) As the first release film and the second release film, release films having surfaces S1 and S2 having Ra and Rz shown in Table 1 were used, respectively. The adhesive composition C obtained above was applied onto the first adhesive surface S1 of the first release film so that the thickness after drying was 20 μm, and the adhesive composition C was dried by heating at normal pressure at 60° C. for 1 minute and at 120° C. for 3 minutes, and then aged at 23° C. for 120 hours to form a photocurable adhesive layer (substrate-less double-sided adhesive sheet). The second adhesive surface S2 of the second release film was attached to the surface of this photocurable adhesive layer for protection. In this way, a substrate-less double-sided adhesive sheet was produced, which was composed only of a photocurable acrylic adhesive layer (also referred to as adhesive C) and in which each side of the photocurable acrylic adhesive layer was protected by the first and second release films.

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

[0235] <Examples 6-7> The first and second release films used were release films having surfaces S1 and S2 with Ra and Rz shown in Table 1. The thickness of the adhesive layer was changed to 25 μm in Example 6. The rest of the process was the same as in Example 1 above to produce substrate-less double-sided adhesive sheets according to each example.

[0236] <Evaluation> The adhesive sheets with release film of each example were evaluated for total light transmittance [%], haze value [%], adhesion to glass [N / 20 mm], peeling force of the release film [N / 50 mm], 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 adhesive sheet of Example 4 was subjected to measurement of elastic modulus by tensile test, and the adhesive sheets of Examples 1 to 4 were subjected to impact resistance test. Table 1 also shows an overview of each example (release surface Ra and Rz of the release film, adhesive type, adhesive sheet thickness [μm], 25°C storage elastic modulus [Pa], gel fraction [%]).

[0237] [Table 1]

[0238] As shown in Table 1, in Examples 1 to 5, the maximum height Rz of the adhesive side surface of the release film was 400 nm or less, and in the pressure-sensitive adhesive sheets of these examples, after the release film was peeled off, no optical distortion was observed, 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 of 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 to 7, the maximum height Rz of the adhesive side surface of the release film exceeded 400 nm, and unevenness was observed in the optical distortion evaluation. The elastic modulus in the tensile test of the pressure-sensitive adhesive sheet of Example 4 was 3.0 MPa or more, and the pressure-sensitive adhesive sheets of Examples 1 to 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 examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples exemplified above. [Explanation of symbols]

[0240] 1, 2 Adhesive sheet with release film 10 Adhesive sheet 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 surface S1 (release surface), adhesive surface (release surface) 22 Second release film 22a 2nd adhesive side surface S2 (release surface) 50 cores 100, 200 rolls (adhesive sheet roll)

Claims

1. The adhesive sheet has a pressure-sensitive adhesive layer, and a release film laminated on the adhesive surface of the pressure-sensitive adhesive sheet. A pressure-sensitive adhesive sheet with a release film, wherein the maximum height Rz of the adhesive surface of the release film is 400 nm or less.

2. 2. The pressure-sensitive adhesive sheet with a release film according to claim 1, wherein the surface of the release film has an arithmetic mean roughness Ra of 30 nm or less.

3. 3. The pressure-sensitive adhesive sheet with a release film according to claim 1, wherein a peel strength of said release film from said pressure-sensitive adhesive sheet is 1 N / 50 mm or less.

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

5. The pressure-sensitive adhesive sheet with a release film according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive sheet has a total light transmittance of 85% or more and a haze value of 1% or less.

6. The pressure-sensitive adhesive sheet with a release film according to any one of claims 1 to 5, wherein the pressure-sensitive adhesive sheet is a single-sided pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer and a supporting substrate laminated on one side of the pressure-sensitive adhesive layer.

7. the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet having a first pressure-sensitive adhesive surface and a second pressure-sensitive adhesive surface, The release film includes a first release film disposed on the first adhesive surface and a second release film disposed on the second adhesive surface, The maximum height Rz of the first adhesive surface S1 of the first release film １ and the maximum height Rz of the second adhesive surface S2 of the second release film ２ The pressure-sensitive adhesive sheet with a release film according to any one of claims 1 to 5, wherein each of the thicknesses of the first and second electrodes is 400 nm or less.

8. the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet having a first pressure-sensitive adhesive surface and a second pressure-sensitive adhesive surface, The release film is a double-sided release film having a first release surface and a second release surface, The maximum height Rz of the first release surface of the release film １ and the maximum height Rz of the second release surface of the release film ２ The pressure-sensitive adhesive sheet with a release film according to any one of claims 1 to 5, wherein each of the thicknesses of the first and second electrodes is 400 nm or less.

9. The pressure-sensitive adhesive sheet with a release film according to any one of claims 1 to 8, wherein the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer.

10. The pressure-sensitive adhesive sheet with a release film according to any one of claims 1 to 9, wherein the pressure-sensitive adhesive layer has a gel fraction of 30 to 95% by weight.

11. The storage modulus of the pressure-sensitive adhesive layer at 25° C. is 4×10 4 The pressure-sensitive adhesive sheet with a release film according to any one of claims 1 to 10, wherein the elastic modulus is 1 Pa or more.

12. The pressure-sensitive adhesive sheet with a release film according to any one of claims 1 to 11, wherein the pressure-sensitive adhesive sheet has a thickness of 5 to 100 µm.

13. The pressure-sensitive adhesive sheet with a release film according to any one of claims 1 to 12, wherein the pressure-sensitive 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 adhesive sheet is exposed to an illuminance of 300 mW / cm ２ , cumulative light amount 3000 mJ / cm ２ After aging at 50° C. for 48 hours, the pressure-sensitive adhesive layer is cut to a size of 10 mm in width and 150 mm in length to prepare a test piece. A tensile test is performed on the test piece using a tensile tester under conditions of 23° C., 50% RH, 120 mm between-chuck distance, and 50 mm / min tensile speed to obtain a stress-displacement curve, and the elastic modulus [MPa] is calculated from the initial slope.

14. The pressure-sensitive adhesive sheet has an impact resistance of 2.0 J / 10 mm as measured by the following shear impact test. ２ The pressure-sensitive adhesive sheet with a release film according to any one of claims 1 to 13, wherein [Shear impact test] A shear impact test is performed using a pendulum-type adhesive shear impact tester based on JIS K6855. As a measurement sample, the first surface of the pressure-sensitive adhesive sheet of 10 mm square is attached to the center of a chemically strengthened glass plate of 25 mm square and 1.7 mm thick, and then the second surface of the pressure-sensitive adhesive sheet is attached to the center of a stainless steel plate (SUS304BA plate) of 40 mm square, and pressed with a load of 5 N for 10 seconds, and then autoclaved (50°C, 0.5 MPa, 15 minutes), and the illuminance from the glass plate side is 300 mW / cm. ２ , cumulative light amount 3000 mJ / cm ２ After irradiation with ultraviolet light under the above conditions, the film is aged at 50° C. for 48 hours before use. The measurement sample was fixed so that the stainless steel plate was on the lower side, and a hammer was applied to the outer peripheral side surface of the glass plate under conditions of a hammer energy of 2.75 J and a hammer speed of 3.5 m / sec in an environment of 23° C. and 50% RH, and the absorbed energy [J] was measured to determine the impact resistance [J / 10 mm ２ ] is required.

15. The pressure-sensitive adhesive sheet with a release film according to any one of claims 1 to 14, wherein the pressure-sensitive adhesive layer contains a polymer (A) and a photoreactive monomer (B).

16. 16. The pressure-sensitive adhesive sheet with a release film according to claim 15, wherein the photoreactive monomer (B) comprises a compound B1 having a ring structure and two or more ethylenically unsaturated groups in the molecule, and the compound B1 has a molecular weight per one ethylenically unsaturated group of 100 g / mol or more.

17. The pressure-sensitive adhesive sheet with a release film according to any one of claims 1 to 16, which is used for fixing a member having an image display surface, a decorative surface or a colored surface to a transparent member.

18. A pressure-sensitive adhesive sheet roll with a release film, comprising the pressure-sensitive adhesive sheet with a release film according to any one of claims 1 to 17 wound thereon.

Images