Adhesive sheet with release film

Abstract

The invention relates to an adhesive sheet with a release film. Provided is an adhesive sheet with a release film. Provided is an adhesive sheet having an adhesive surface having high surface smoothness. According to the present specification, provided is an adhesive sheet with a release film, which is provided with an adhesive sheet and a release film laminated on the 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 less than 400 nm.

Description

[0001] This application is a divisional application of an application with the application number 202110342365.2, the application date of March 30, 2021, and the title of “Adhesive sheet with release film”. TECHNICAL FIELD

[0002] The present application relates to an adhesive sheet with a release film. BACKGROUND

[0003] Generally, an adhesive (also referred to as a pressure-sensitive adhesive. The same applies hereafter.) has a property of exhibiting a soft solid (viscoelastic body) state in a temperature range around room temperature, and easily adhering to an adherend by pressure. By virtue of this property, the adhesive is widely used in various industrial fields such as home electric appliances, automobiles, OA equipment, and the like, in the form of an adhesive sheet including a layer of the adhesive.

[0004] Among the above-mentioned adhesive sheets, sometimes a high smoothness is required for the adhesive surface (surface of the adhesive layer). As an example of such an adhesive sheet, an adhesive sheet for optical use can be cited. For example, in Japanese Patent No. 4673344 and Japanese Patent No. 4805999, it is described that the surface roughness (Ra) of the adhesive layer of an optical adhesive sheet is set to a prescribed range with the purpose of improving visual recognition. In addition, in Japanese Patent Application Laid-Open No. 2017-105974, it is described that the ten-point average roughness of the adhesive surface of an adhesive sheet usable for optical use is set to about 1000 nm or less. Furthermore, in Japanese Patent No. 4069625, it is described that in an adhesive sheet to be attached to an optical member such as a polarizing plate, the surface roughness (Ra) of a release film disposed on the surface of the adhesive layer is set to 0.1 μm or less. In Japanese Patent No. 6300788, it is described that the surface roughness (Ra) and the maximum protrusion height (Rp) of a release film are set to a prescribed range. SUMMARY

[0005] In various products such as portable electronic devices, an adhesive sheet can be used in a region to be visually recognized from the outside. For example, an adhesive sheet for a portable electronic device can be used not only on an image display surface of the electronic device but also on a surface other than the same (for example, a back surface). Therefore, for an adhesive sheet used in such a use, sometimes a high transparency not to be felt as its existence is required, and furthermore, a high smoothness can be required for the adhesive surface. If orange peel and streaks exist on the adhesive surface, the visual recognition through the adhesive sheet is reduced, and sometimes the appearance design, the beauty, and the high-class feeling possessed by the surface of the adherend are impaired.

[0006] While not particularly limited, as one use in which it is desired to have a highly smooth adhesive surface, the following use can be cited: attaching a film in which a design including a specific color tone such as a metallic color tone is implemented to the inner side of a transparent case constituting a portable electronic device, so that the design formation surface (decorative surface) thereof becomes the transparent case side. With respect to the adhesive sheet used for the fixation of the above-described transparent case and film, since both adhesive surfaces can affect visual recognition, it is desirable that both adhesive surfaces have high smoothness. Even with an adhesive sheet having a smoothness that has been considered to be a level of acceptance in the past, optical distortion and the like are observed under more highly accurate evaluation conditions, and it cannot necessarily be said that the surface smoothness thereof is at a satisfactory level. If an adhesive sheet having an adhesive surface with higher smoothness can be achieved, it is practically advantageous as a joining means that does not impair the design, beauty, and high-class feel of the adherend.

[0007] The present application was made in view of the above-described circumstances, and aims to provide an adhesive sheet having an adhesive surface with high surface smoothness in a state protected by a release film.

[0008] According to the present specification, a release film-equipped adhesive sheet is provided. The release film-equipped adhesive sheet has: an adhesive sheet having an adhesive layer, and a release film layered on the adhesive surface of the adhesive sheet. In addition, the maximum height Rz of the adhesive surface side surface of the aforementioned release film is 400 nm or less.

[0009] According to the above-described configuration, the adhesive surface of the adhesive sheet is protected by the release film in a state 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 attached to an adherend, the adhesive surface has high surface smoothness with respect to the adherend, and adhesive bonding without optical distortion or with optical distortion suppressed can be achieved.

[0010] In some preferred modes, the arithmetic average roughness Ra of the aforementioned surface of the aforementioned release film is 30 nm or less. According to this configuration, a configuration in which the adhesive surface has high surface smoothness can be preferably achieved.

[0011] In some preferred modes, the release force of the aforementioned release film with respect to the aforementioned adhesive sheet is 1 N / 50 mm or less. With this configuration, when the release film is removed from the adhesive surface at the time of use of the adhesive sheet, fine corrugations of the adhesive surface based on so-called stick-slip phenomena caused by release from the release film are suppressed, and thus a smoother adhesive surface is easily obtained.

[0012] In several preferred embodiments, the aforementioned release film has a thickness in the range of 50 to 125 μm. With such a configuration, the release film has a sufficient thickness, and it is possible to prevent an event (dishing) in which the smoothness of the adhesive sheet surface is damaged beyond the release film. Such an event can be caused by a foreign object interposed between the release films when the adhesive sheet with the release film is taken up into a roll, for example. In addition, by setting the thickness of the release film to a value below the prescribed value, removal of the adhesive sheet becomes smooth, and the adhesive surface of the adhesive sheet is also easily maintained in a high surface smoothness after the release film is removed.

[0013] In several preferred embodiments, the aforementioned adhesive sheet has a total light transmittance of 85% or more and a haze value of 1% or less. With the adhesive sheet satisfying the aforementioned characteristics, it is easy to visually recognize the adherend through the adhesive sheet without impairing the visual recognition of the appearance design or the like possessed by the adherend.

[0014] In several embodiments, the aforementioned adhesive sheet is a single-coated adhesive sheet having the aforementioned adhesive layer and a support substrate laminated on one face of the adhesive layer. The effects obtained by the technology disclosed herein can be preferably achieved in the embodiments in which the single-coated adhesive sheet is used. In this embodiment, the support substrate can be a transparent substrate.

[0015] In other several embodiments, the aforementioned adhesive sheet is a double-coated adhesive sheet having a first adhesive face and a second adhesive face. In addition, in the adhesive sheet with the release film, as the release film, there are a first release film disposed on the aforementioned first adhesive face and a second release film disposed on the aforementioned second adhesive face. Furthermore, the maximum height Rz1 of the aforementioned first adhesive face side surface S1 of the aforementioned first release film and the maximum height Rz2 of the aforementioned second adhesive face side surface S2 of the aforementioned second release film are each 400 nm or less. In this configuration as well, the effects obtained by the technology disclosed herein can be preferably achieved. In this configuration, it is preferable that the arithmetic mean roughness Ra1 of the aforementioned surface S1 of the aforementioned first release film and the arithmetic mean roughness Ra2 of the aforementioned surface S2 of the aforementioned second release film are each 30 nm or less. In addition, the release force of the aforementioned first release film with respect to the aforementioned adhesive sheet and the release force of the aforementioned second release film with respect to the aforementioned adhesive sheet can each be 1 N / 50 mm or less. Furthermore, the thickness of the aforementioned first release film and the thickness of the aforementioned second release film can each be in the range of 50 to 125 μm.

[0016] In some other embodiments, the aforementioned adhesive sheet is a double-sided adhesive sheet having a first adhesive surface and a second adhesive surface. In addition, the aforementioned release film is a double-sided release film having a first release surface and a second release surface. Furthermore, the maximum height Rz1 of the aforementioned first release surface of the aforementioned release film and the maximum height Rz2 of the aforementioned second release surface of the aforementioned release film are each 400 nm or less. In this configuration, the effects disclosed herein can be preferably achieved. In this configuration, it is preferable that the arithmetic mean roughness Ra1 of the aforementioned first release surface and the arithmetic mean roughness Ra2 of the aforementioned second release surface are each 30 nm or less. In addition, the release force of the aforementioned first release surface with respect to the aforementioned adhesive sheet and the release force of the aforementioned second release surface with respect to the aforementioned adhesive sheet can each be 1 N / 50 mm or less.

[0017] In some preferred embodiments, the aforementioned adhesive layer is an acrylic adhesive layer. When an acrylic adhesive is used, it is possible to achieve the target adhesive properties, viscoelastic properties excellent in impact resistance, without using an additive ingredient such as a softening agent that can be a cause of reduction in transparency, or limiting the amount of additive, thus easily achieving both transparency and adhesive properties, viscoelastic properties. In addition, acrylic adhesives have a tendency to be excellent in color change resistance compared to, for example, rubber-based adhesives, and are also advantageous from the viewpoint of maintaining transparency over a long period of time.

[0018] In some preferred embodiments, the gel fraction of the aforementioned adhesive layer is 30 to 95% by weight. By making the gel fraction of the adhesive layer 95% by weight or less, the adhesive sheet has a tendency to be excellent in height difference followability. Thus, it is possible to adhere to a surface of an adherend having a height difference. For example, in the case where a print such as a mark is formed on the surface of the adherend, the adhesive sheet is able to follow the unevenness of the print well without impairing visual recognition. In addition, by making the gel fraction of the adhesive layer 30% by weight or more, there is a tendency to easily achieve good adhesive properties, viscoelastic properties. For example, when a configuration is employed in which the adhesive layer has the aforementioned gel fraction, there is a tendency to be less likely to cause dents, and also excellent in deformation resistance.

[0019] In some preferred embodiments, the storage modulus at 25°C of the aforementioned adhesive layer is 4 x 10 4 Pa or more. The adhesive layer having the aforementioned storage modulus at 25°C has a tendency to have preferable heat resistance, and easily achieves good adhesive properties such as deformation resistance.

[0020] In some preferred embodiments, the thickness of the aforementioned adhesive sheet is 5 to 100 μm. The adhesive sheet having a thickness of 5 μm or more has a tendency to be excellent in height difference followability, and easily absorbs deformation caused by foreign matter or the like. In addition, by making the aforementioned thickness 100 μm or less, the adhesive sheet is less likely to be strained, and high adhesive surface smoothness is easily achieved.

[0021] In some preferred embodiments, the aforementioned adhesive sheet has an elastic modulus of 3.0 MPa or more as determined by the following tensile test. By satisfying the aforementioned properties, the adhesive sheet can exhibit high resistance to deformation.

[0022] [Tensile test]

[0023] For the aforementioned adhesive sheet, the adhesive layer was irradiated with ultraviolet rays under conditions of an irradiance of 300 mW / cm 2 , a cumulative light amount of 3000 mJ / cm 2 , and was allowed to cure for 48 hours at 50°C, and then the aforementioned adhesive layer was cut into a size of 10 mm in width and 150 mm in length, thereby producing a test piece. A tensile test of the aforementioned test piece was performed using a tensile testing machine under conditions of a chuck distance of 120 mm and a tensile speed of 50 mm / minute in an environment of 23°C and 50% RH, and a stress-displacement curve was obtained, from which an elastic modulus [MPa] was calculated.

[0024] In some preferred embodiments, the aforementioned adhesive sheet has an impact resistance of 2.0 J / 10 mm 2 or more as determined by the following shear impact test. By satisfying the aforementioned properties, the adhesive sheet can exhibit high impact resistance. For example, an adhesive sheet that satisfies the modulus properties based on the aforementioned tensile test and the impact resistance properties described above can be preferably used for the purpose of joining and fixing of members, for example, because of high resistance to deformation and the ability to form a joint with high impact resistance.

[0025] [Shear impact test]

[0026] A shear impact test was performed using a pendulum-type adhesive shear impact testing machine based on JIS K6855. As a measurement sample, a sample was used that was obtained by adhering the first face of a 10 mm square of the aforementioned adhesive sheet to the central portion of a 25 mm square chemical-strengthened glass plate having a thickness of 1.7 mm, and then adhering the second face of the aforementioned adhesive sheet to the central portion of a 40 mm square stainless steel plate (SUS304BA plate) with a 10 second press bonding at a load of 5 N, followed by autoclave treatment (50°C, 0.5 MPa, 15 minutes), and then irradiating the aforementioned glass plate side with ultraviolet rays under conditions of an irradiance of 300 mW / cm 2 , a cumulative light amount of 3000 mJ / cm 2 , and then allowing to cure for 48 hours at 50°C.

[0027] The aforementioned measurement sample was fixed with the aforementioned stainless steel plate as the lower side, and the absorbed energy [J] when a hammer was struck against the outer peripheral side face of the aforementioned glass plate at a hammer energy of 2.75 J and a hammer speed of 3.5 m / second was measured in an environment of 23°C and 50% RH, thereby calculating the impact resistance [J / 10 mm 2].

[0028] In several preferred modes, the aforementioned adhesive layer contains the polymer (A) and the photoreactive monomer (B). Further, more preferably, the aforementioned photoreactive monomer (B) comprises a compound B1 having a ring structure and 2 or more ethylenically unsaturated groups in the molecule, the molecular weight of the compound B1 being 100 g / mol or more per 1 ethylenically unsaturated group. With the adhesive sheet having the aforementioned adhesive layer, the resistance to deformation is high and the joining with high impact resistance can be suitably formed.

[0029] With the adhesive sheet with a release film disclosed herein, an adhesive sheet in which both of the adhesive surfaces have high surface smoothness can be realized, and thus is preferably used for a use of fixing a member having an image display surface, a decorative surface, or a colored surface, which often requires high visual recognition, to a transparent member. For example, in a mode of fixing a decorative surface of a decorative film to a transparent member, and the like, the adhesive sheet suppresses optical distortion, and thus the decorative surface is easily visually recognized through the adhesive sheet, and can function as a joining means which does not impair the appearance design, the beauty, and the high-class feeling of the decorative surface.

[0030] The adhesive sheet with a release film disclosed herein can be provided in the form of an adhesive sheet with a release film roll in which the adhesive sheet with a release film is wound. Such a roll is easy to handle at the time of storage and transportation, and is also advantageous in terms of productivity. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 A cross-sectional view of an adhesive sheet with a release film of an embodiment is shown.

[0032] Figure 2 A cross-sectional view of an adhesive sheet with a release film of another embodiment is shown. DETAILED DESCRIPTION

[0033] Suitable embodiments of the present application are described below. Note that matters other than those specifically mentioned in this specification and matters necessary for the implementation of the present application can be understood by those skilled in the art from the teachings of the present specification regarding the implementation of the application and the technical common sense at the time of filing. The present application can be implemented in accordance with the content disclosed in the present specification and the technical common sense in the field. In addition, in the following drawings, sometimes the same symbol is given to members / positions that function in the same manner to describe them, and sometimes repeated descriptions are omitted or simplified. In addition, the embodiments described in the drawings are schematically shown for the purpose of clearly illustrating the present application, and do not necessarily accurately show the dimensions, scales of actually provided products.

[0034] In this specification, "adhesive" means, as previously described, a material that exhibits a soft solid state (viscoelasticity) in a temperature range near room temperature and readily bonds to substrates under pressure. The adhesive referred to here, as defined in "CA Dahlquist, 'Adhesion: Fundamental and Practice', McLaren & Sons, (1966) p. 143", is generally a material that satisfies the complex tensile modulus E * (1Hz) <10 7 dyne / cm 2 Materials with the above properties (representatively, materials that have the above properties at 25°C).

[0035] In this specification, "acrylic polymer" refers to a polymer derived from a monomeric component containing more than 50% by weight of an acrylic monomer, also known as an acrylic class polymer. The aforementioned acrylic monomer refers to a monomer having at least one (meth)acryloyl group in one molecule. Furthermore, in this specification, "(meth)acryloyl" refers to both acryloyl and methacryloyl groups. Similarly, "(meth)acrylate" refers to both acrylate and methacrylate; and "(meth)acrylic acid" refers to both acrylic acid and (meth)acrylic acid.

[0036] It should be noted that in this instruction manual, "mass" and "weight" have the same meaning.

[0037] In this specification, a "photoreactive monomer" is a compound having at least one functional group (photoreactive functional group) within its molecule that can undergo a reaction by light irradiation. Typically, a compound having at least one olefinic unsaturated group as the aforementioned photoreactive functional group is a typical example. The photoreactive monomer referred to here only needs to be capable of reacting as a monomer; for example, it can itself be an oligomer, polymer, or other polymer (e.g., a polymer having at least one olefinic unsaturated group within its molecule).

[0038] In addition, in this specification, "photocurable" refers to the property of curing by irradiation with light such as ultraviolet light. For example, a photocurable adhesive composition refers to a composition that is cured by light curing to become an adhesive or adhesive layer. Furthermore, a photocurable adhesive layer refers to an adhesive layer that can be cured by irradiation with light such as ultraviolet light. This term is used to refer to the adhesive layer before the light curing treatment, which is an adhesive layer that has been fully cured by light curing. A photocurable adhesive sheet is used to refer to an adhesive sheet having such a photocurable adhesive layer.

[0039] <Example of the construction of an adhesive sheet with a release film>

[0040] An example of a configuration of the adhesive sheet with a release film disclosed herein is given below. Figure 1 The adhesive sheet 1 with a release film 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 located on the opposite side of the first adhesive surface 10a. In this embodiment, the adhesive sheet 10 is a substrate-free double-sided adhesive sheet composed of an adhesive layer 12; 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 of the first release film 21 is in contact with the first adhesive surface 10a of the adhesive sheet 10 in a peelable manner. 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 peelable manner. The first adhesive side surface (S1) 21a of the first release film 21 and the second adhesive side surface (S2) 22a of the second release film 22 become release surfaces having a release treatment layer based on, for example, an organosilicon-based release agent. In this way, the adhesive sheet 1 with the release film is in a form where 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. Furthermore, when the adhesive sheet 10 is used, the first release film 21 and the second release film 22 are removed, exposing the first adhesive surface 10a and the second adhesive surface 10b, which are then adhered to the object to be bonded.

[0041] Additionally, the adhesive sheet 1 with a release film can be Figure 1 The roll (adhesive sheet roll with release film) 100 is in the form shown. The adhesive sheet roll 100 is formed by winding the adhesive sheet 1 with release film around the core (core) 50.

[0042] The structure of an adhesive sheet with a release film according to another embodiment is schematically shown in [the diagram]. Figure 2 . Figure 2The adhesive sheet 2 with a release film shown 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 (the first side 12a of the adhesive layer 12) of which is the adhesive surface 10a, and the other side is the back side (non-adhesive surface). In this embodiment, the back side of the adhesive sheet 10 is formed by one side of the support substrate 14 (the side of the support substrate 14 opposite to the adhesive layer side surface 14a) 14b. The second side 12b of the adhesive layer 12 is fixed on the other side (adhesive layer side surface) 14a of the support substrate 14, which can be considered a non-peelable surface (non-peelable surface). Thus, the adhesive layer 12 is provided in a manner that does not intend to separate from the support substrate 14. On the other hand, the surface (adhesive side surface S1) 21a of the release film 21 and Figure 1 The first peel film also becomes the peel surface, contacting the adhesive surface 10a of the adhesive layer 12 in a peelable manner, protecting the adhesive surface 10a. This adhesive sheet 2 with the peel film can also be... Figure 2 The form of the wound body (adhesive sheet roll) 200 shown is provided. The adhesive sheet roll 200 has the form of an adhesive sheet 2 with a release film wound around a core (core) 50, the adhesive sheet 2 with the release film having an adhesive sheet 10 and a release film 21, the adhesive sheet 10 having an adhesive layer 12 and a support substrate 14.

[0043] It should be noted that, Figure 1 An example is a wound body 100 formed by winding an adhesive sheet 1 with a release film around a core 50. However, the wound body 100 can also be considered as a so-called coreless wound body that does not have a core 50, i.e., is formed by winding the adhesive sheet 1 with a release film alone. For Figure 2 The same applies to the coil 200 shown.

[0044] in addition, Figure 1 The adhesive sheet 1 shown (before use) has the following configuration: the first adhesive surface 10a and the second adhesive surface 10b are respectively protected by a first release film 21 and a second release film 22, which are at least peelable surfaces (peel surfaces) on the adhesive surface side. However, it is also possible to adopt the following configuration: the second release film 22 is omitted, and a film with peel surfaces on both sides is used as the release film 21. The adhesive sheet 1 is wound so that the second adhesive surface 10b abuts against the back of the release film 21, thereby protecting the second adhesive surface 10b as well as the release film 21.

[0045] In addition, adhesive sheets can be Figure 1 The substrate-free adhesive sheet shown can also be Figure 2The single-sided adhesive sheet with a substrate shown can also be in the form of a double-sided adhesive sheet with a substrate. Specifically, the adhesive sheet can be a substrate-containing adhesive sheet with a non-peelable substrate embedded within it. The substrate can be plastic film, paper, non-woven fabric, etc. Figure 1 , 2 The example illustrates an adhesive layer 10 as a single-layer structure, but the composition of the adhesive layer 10 is not limited to this. For example, the adhesive layer may also consist of two or more sub-adhesive layers formed of the same or different adhesives.

[0046] <Peeling off the film>

[0047] (Maximum height Rz of the adhesive side surface)

[0048] The maximum height Rz of the adhesive side surface of the release film disclosed herein is 400 nm or less. Therefore, the adhesive surface of the adhesive sheet can have high surface smoothness. Furthermore, in the configuration where a first release film and a second release film are respectively disposed on each adhesive surface of the adhesive sheet, the maximum height Rz1 of the first adhesive side surface S1 of the first release film and the maximum height Rz2 of the second adhesive side surface S2 of the second release film are both 400 nm or less. Therefore, each adhesive surface of the double-sided adhesive sheet has high surface smoothness, and both adhesive surfaces exhibit high surface smoothness when bonded to an adherend.

[0049] The maximum height Rz of the adhesive side surface of the release film (including the maximum height Rz1 of the first adhesive side surface S1 of the first release film and the maximum height Rz2 of the second adhesive side surface S2 of the second release film; unless otherwise specified, the same applies below) is preferably about 340 nm or less, more preferably about 280 nm or less, and even more preferably about 240 nm or less, and may be less than 200 nm, less than 150 nm, or less than 120 nm. Furthermore, from the viewpoint of ease of manufacture and processability of the release film, in several embodiments, the aforementioned maximum height Rz may be, for example, about 50 nm or more, about 80 nm or more, or about 100 nm or more. In embodiments comprising a first release film and a second release film, the maximum height Rz1 of the first adhesive side surface S1 of the first release film and the maximum height Rz2 of the second adhesive side surface S2 of the second release film may be at the same level or different.

[0050] (Arithmetic mean roughness Ra of the bonding surface)

[0051] Furthermore, for the release film, from the viewpoint of achieving an adhesive surface with high surface smoothness, it is preferable that the arithmetic mean roughness Ra of the adhesive surface side surface is limited to a specified value or less (e.g., about 100 nm or less, and even less than 50 nm). Additionally, in configurations where a first release film and a second release film are respectively disposed on each adhesive surface of the adhesive sheet, it is appropriate that the arithmetic mean roughness Ra1 of the surface S1 of the first release film and the arithmetic mean roughness Ra2 of the second adhesive surface side surface S2 of the second release film are limited to, for example, about 100 nm or less (and even less than 50 nm). In several embodiments, the arithmetic mean roughness Ra of the adhesive surface side surface of the release film (including the arithmetic mean roughness Ra1 of the first adhesive surface side surface S1 of the first release film and the arithmetic mean roughness Ra2 of the second adhesive surface side surface S2 of the second release film; unless otherwise specified, the same applies below) is preferably about 30 nm or less, can be about 25 nm or less, can be about 20 nm or less, or can be about 18 nm or less. Furthermore, from the viewpoint of ease of manufacturing and processability of the release film, in several embodiments, the aforementioned arithmetic mean roughness Ra can be, for example, about 5 nm or more, about 10 nm or more, or about 15 nm or more. In embodiments comprising a first release film and a second release film, the arithmetic mean roughness Ra1 of the first adhesive surface S1 of the first release film and the arithmetic mean roughness Ra2 of the second adhesive surface S2 of the second release film can be at the same level or different.

[0052] (Surface characteristics of the back side)

[0053] The maximum height Rz and arithmetic mean roughness Ra of the back side (opposite to the adhesive layer side) of the release film (including the first release film and the second release film) are not particularly limited. From a productivity perspective, the maximum height Rz of the back side (opposite to the adhesive layer side) of the release film can exceed 400 nm (e.g., about 500 nm or more) or 800 nm (e.g., 1000 nm or more). The arithmetic mean roughness Ra of the back side (opposite to the adhesive layer side) of the release film can exceed 30 nm (e.g., more than 35 nm, and further, about 50 nm or more) from a productivity perspective.

[0054] The maximum height Rz and arithmetic mean roughness Ra of the release film surface can be adjusted by the selection of film material, forming method, surface treatment such as release treatment. For example, the smoothness of the layers constituting the release surface (anti-adhesion layer, hard coating, anti-oligomery layer, etc.) can be adjusted; the amount of filler particles in the surface layer and the release film substrate can be reduced or eliminated (no particles); and the stretching conditions can be adjusted.

[0055] The maximum height Rz and arithmetic mean roughness Ra of the peeled film surface were measured using a non-contact surface roughness measuring device. As a non-contact surface roughness measuring device, an optical interferometry surface roughness measuring device was used, such as a three-dimensional optical profilometer (trade name "NewView7300", manufactured by ZYGO) or its equivalent. For example, a glass plate (1.3 μm thick, soda-lime glass plate manufactured by MATSUNAMI) was adhered and fixed to the side of the peeled film opposite to the measurement surface, and the surface shape was measured using a three-dimensional optical profilometer (trade name "NewView7300", manufactured by ZYGO) at 23°C and 50%RH. The same method was used in the embodiments described later. The specific measurement conditions and calculation methods were the same as those for measuring the maximum height Rz and arithmetic mean roughness Ra of the adhesive sheet bonding surface described in the embodiments described later.

[0056] The release film (including the first release film and the second release film; unless otherwise specified, the same applies below) may be selected from release films with a maximum height Rz of 400 nm or less on the adhesive side surface. 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 formed from low-adhesion resins such as fluoropolymers (polytetrafluoroethylene, etc.) and polyolefin resins (polyethylene, polypropylene, etc.).

[0057] As the release film disclosed herein, a release film having a release treatment layer on the release film substrate is preferably used. The release treatment layer can be formed by surface treatment of the release film substrate with a release treatment agent. The release treatment agent can be a known release treatment agent such as a silicone-based release treatment agent, a long-chain alkyl-based release treatment agent, a fluorinated release treatment agent, or molybdenum sulfide (IV). Among several embodiments, a release film having a release treatment layer based on a silicone-based release treatment agent is preferred. The thickness and formation method of the release treatment layer are not particularly limited, and can be set in a manner that provides appropriate peelability on the adhesive side surface of the release film.

[0058] Various plastic films can be used as the substrate for release films. In this specification, plastic film refers to non-porous sheets and is a concept to distinguish it from, for example, nonwoven fabrics (i.e., excluding nonwoven fabrics).

[0059] Examples of materials used for the aforementioned plastic films 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 cellulose triacetate; acetate resins; polysulfone resins; polyethersulfone resins; polycarbonate resins; polyamide resins; polyimide resins; norbornene resins; cyclic polyolefin resins such as (meth)acrylic acid 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 any one or a mixture of two or more of these resins can be used. A preferred release film substrate is a polyester resin film (e.g., PET film) formed from a polyester resin.

[0060] The plastic film used as the release film substrate can be any of unstretched film, uniaxially stretched film, or biaxially stretched film. Furthermore, the plastic film can be a single-layer structure or a multi-layer structure containing two or more sub-layers. The plastic film may contain known additives suitable for release film substrates used in adhesive sheets, such as antioxidants, anti-aging agents, heat stabilizers, light stabilizers, ultraviolet absorbers, colorants such as pigments or dyes, lubricants, fillers, antistatic agents, and nucleating agents. In multi-layer plastic films, each additive may be mixed in all sub-layers or only in a portion of the sub-layers.

[0061] In several preferred embodiments, the release film substrate (typically a plastic film) is preferably one in which the content of inorganic particles (e.g., pigments, lubricants, fillers, etc.) in the layer on its release surface side is limited or substantially free of such particles. Here, "substantially free" means that the amount of particles (e.g., inorganic particles) in that layer is less than 1% by weight, preferably less than 0.1% by weight (e.g., 0 to 0.01% by weight). For a release film having such a release film substrate, the maximum height Rz of the release surface and the arithmetic mean roughness Ra tend to be lower. When the release film substrate (typically a plastic film) has a multilayer structure, the particle content in the layer on the release surface side can be less than 1 / 10 (e.g., less than 1 / 50) of the particle content in layers other than the layer on the release surface side.

[0062] In a configuration having a first release film and a second release film, the first release film and the second release film may have the same material and structure, or they may have different materials and structures.

[0063] The thickness of the release film is not particularly limited, and can be, for example, around 10 μm to 500 μm. From the viewpoint of the strength and dimensional stability of the release film, a thickness of 20 μm or more is appropriate, preferably 30 μm or more, and can be 35 μm or more, or 40 μm or more, or 45 μm or more. In several preferred embodiments, the thickness of the release film is about 50 μm or more, about 60 μm or more, or about 70 μm or more. Thus, the release film has sufficient thickness to prevent events (dents) that damage the smoothness of the adhesive sheet surface by extending beyond the release film. Furthermore, from the viewpoint of the processability of the release film (e.g., ease of winding), a thickness of 300 μm or less is appropriate, preferably 250 μm or less, and can be 200 μm or less, or 150 μm or less, or 130 μm or less. In several preferred embodiments, the thickness of the release film is about 125 μm or less, or about 115 μm or less, or about 105 μm or less, or about 90 μm or less. By setting the thickness of the release film to a specified value or less, roll marks are less likely to occur when forming the roll, the removal of the self-adhesive sheet becomes smoother, and the adhesive surface of the adhesive sheet easily maintains a high surface smoothness after the release film is removed.

[0064] In the configuration of having a first release film and a second release film, the thicknesses of the first release film and the second release film may be the same or different. From the viewpoint of ease of peeling operation, it is preferable that the first release film and the second release film have different thicknesses, and preferably the thickness of the thicker release film is at least 1.1 times, for example, at least 1.25 times, the thickness of the thinner release film.

[0065] It should be noted that a carrier or auxiliary film can be adhered to the back of the release film as needed. The presence of this back auxiliary film makes it easier to prevent dents, even when using a thin release film, and improves operability in processes such as die-cutting. Known or conventional adhesive tapes with resin film substrates can be used as this back auxiliary film.

[0066] <Peeling force of the peeling film>

[0067] Preferably, in the adhesive sheet with a release film disclosed herein, the peeling force of the release film on the adhesive sheet is limited to a specified value or less. Therefore, when the release film is removed from the adhesive surface during use of the adhesive sheet, fine ripples on the adhesive surface caused by the peeling of the release film due to a so-called stick-slip phenomenon are suppressed, resulting in a smoother adhesive surface. In several 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 from the viewpoint of protecting the release film and preventing it from lifting, it can be 0.05 N / 50 mm or more. The peeling force of the peeling film can be adjusted by peeling treatment of the peeling film surface, etc.

[0068] In the configuration of having a first release film and a second release film, from the viewpoint of peeling operability, it is preferable that the peeling force of the first release film on the adhesive sheet and the peeling force of the second release film on the adhesive sheet are different. For example, it is appropriate, preferably about 1.4 times or more, about 1.5 times or more, or about 1.8 times or more of the peeling force of the release film on the light peeling side (e.g., the first release film) from the viewpoint of maintaining light peelability, it is appropriate, preferably about 3 times or less, of the peeling force of the release film on the light peeling side (e.g., the first release film) from the viewpoint of maintaining light peelability, or about 2 times or less.

[0069] The peel force of the release film was measured as follows: an adhesive sheet with a release film, 150 mm long and 50 mm wide, was prepared and measured at 23°C, 50%RH, a stretching speed of 300 mm / min, and a peel angle of 180°. Specifically, the measurement was performed using the method described in the examples below.

[0070] <Adhesive Sheet>

[0071] (Surface properties of the adhesive surface)

[0072] The adhesive sheet disclosed herein has an adhesive surface whose maximum height Rz is limited to a specified value. When the adhesive surface is designed to minimize the maximum height Rz, high surface smoothness is achieved, resulting in zero or suppressed optical distortion. This adhesive sheet allows for visual identification of the surface of the adhered object without compromising its appearance, such as its aesthetics or premium feel, for example, when the surface of the adhered object is visually recognized through the adhesive sheet. When the adhesive sheet is a double-sided adhesive sheet with adhesive surfaces on both sides, it is appropriate that the maximum height Rz of the first and second adhesive surfaces constituting the double-sided adhesive sheet is limited to a specified value. The high surface smoothness of each adhesive surface of the double-sided adhesive sheet enables adhesion with zero or highly suppressed optical distortion. For example, when one side of the adhered object is transparent and the other side has an appearance design, the appearance design of the adhered object can be clearly visually identified through the adhesive sheet.

[0073] The maximum height Rz of the adhesive surface of the adhesive sheet (including the first adhesive surface and the second adhesive surface; unless otherwise specified, the same applies below) is preferably about 600 nm or less, more preferably about 500 nm or less, further preferably about 450 nm or less, particularly preferably about 400 nm or less, and may be less than 350 nm, less than 300 nm, or less than 250 nm. From the viewpoint of production efficiency, in several embodiments, the maximum height Rz of the adhesive surface of the adhesive sheet may be, for example, about 10 nm or more, about 50 nm or more, about 100 nm or more, or about 200 nm or more. In the embodiment where 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 at the same level or different.

[0074] The adhesive surface of the adhesive sheet disclosed herein preferably has an arithmetic mean roughness Ra that is limited to a specified value or below. When a configuration is used that has an adhesive surface designed to have a low arithmetic mean roughness Ra, optical distortion is easily suppressed. When the adhesive sheet is in the form of a double-sided adhesive sheet with adhesive surfaces on both sides, it is appropriate that the arithmetic mean roughness Ra of the first and second adhesive surfaces constituting the double-sided adhesive sheet is limited to a specified value or below. By ensuring high surface smoothness on each adhesive surface of the double-sided adhesive sheet, adhesion with no optical distortion or with highly suppressed optical distortion can preferably be achieved.

[0075] The arithmetic mean roughness Ra of the bonding surface of the adhesive sheet is preferably about 70 nm or less, more preferably about 65 nm or less, 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, in several embodiments, the arithmetic mean roughness Ra of the bonding 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 (e.g., about 40 nm or more). In the embodiment where the adhesive sheet has a first bonding surface and a second bonding surface, the arithmetic mean roughness Ra of the first bonding surface and the arithmetic mean roughness Ra of the second bonding surface may be at the same level or different.

[0076] It should be noted that the maximum height Rz and arithmetic mean roughness Ra of the adhesive surface can be adjusted by the surface properties of the release film stacked on the adhesive surface, the peeling force of the release film on the adhesive sheet, and the thickness of the adhesive layer.

[0077] Furthermore, the maximum height Rz of the bonding surface of the aforementioned adhesive sheet can be the maximum height Rz of the adhesive layer surface constituting the adhesive sheet. Similarly, the arithmetic mean roughness Ra of the bonding surface of the aforementioned adhesive sheet can be the arithmetic mean roughness Ra of the adhesive layer surface constituting the adhesive sheet. Therefore, the range and value of the maximum height Rz and the arithmetic mean roughness Ra of the adhesive layer surface can be respectively adopted from the range and value recorded as the maximum height Rz and the arithmetic mean roughness Ra of the bonding surface of the aforementioned adhesive sheet.

[0078] Furthermore, the maximum height Rz and arithmetic mean roughness Ra of the adhesive surface of the adhesive sheet are measured as follows: The adhesive surface of the adhesive sheet after the release film has been peeled off from the adhesive sheet with the release film is measured using a non-contact surface roughness measuring device. As a non-contact surface roughness measuring device, an optical interferometry surface roughness measuring device is used, for example, a three-dimensional optical profilometer (trade name "NewView7300", manufactured by ZYGO Corporation) or its equivalent can be used. Specific measurement operations and conditions can be set according to the measurement conditions described in the embodiments described later, or in a manner that yields results equivalent to or corresponding to those obtained under those measurement conditions.

[0079] (Total transmittance)

[0080] In several embodiments, it is appropriate for the total light transmittance of the adhesive sheet to be, for example, about 50% or more, or, for example, about 70% or more. From the viewpoint of visual recognizability of the adhered object through the adhesive sheet, in several preferred embodiments, the total light transmittance of the adhesive sheet is about 85% or more, more preferably about 90% or more. The upper limit of the above-mentioned total light transmittance is theoretically a value obtained by subtracting the light loss (Fresnel loss) caused by reflection at the air interface from 100%, and practically it can be about 95% or less, or about 94% or less (e.g., 93% or less). When using an adhesive sheet with such a total light transmittance, good visual recognizability can be obtained through the adhesive sheet.

[0081] (Haze value)

[0082] In several embodiments, the haze value of the adhesive sheet may be, for example, about 10% or less, or about 3% or less. From the viewpoint of visual recognizability of the adhered object through the adhesive sheet, in several preferred embodiments, the haze value of the adhesive sheet is about 1% or less, more preferably about 0.8% or less, and even more preferably about 0.5% or less. The lower limit of the above haze value is theoretically 0%, and practically it can exceed about 0.0%. It should be noted that "haze value" refers to the ratio of diffuse transmitted light to total transmitted light when visible light is irradiated onto the object being measured. It is also called the haze value. The haze value can be expressed by the following formula.

[0083] Th[%]=Td / Tt×100

[0084] In the above formula, Th is the haze value [%], Td is the scattered light transmittance, and Tt is the total transmittance.

[0085] It should be noted that the total light transmittance and haze value of the adhesive sheet can be adjusted by the composition (base polymer type, added components) and thickness of the adhesive sheet (representatively the adhesive layer).

[0086] Furthermore, the total light transmittance of the aforementioned adhesive sheet can be the total light transmittance of the adhesive layer constituting the adhesive sheet. Similarly, the haze value of the aforementioned adhesive sheet can be the haze value of the adhesive layer constituting the adhesive sheet. Therefore, the range and value of the total light transmittance and haze value of the adhesive layer can be respectively adopted from the range and value recorded as the total light transmittance and haze value of the aforementioned adhesive sheet.

[0087] Furthermore, the total light transmittance and haze value of the adhesive sheet can be measured by attaching the adhesive sheet to one side of a glass plate and using a haze meter. The haze meter can be the "HM-150N" device manufactured by Murakami Color Technology Research Institute or an equivalent. Specifically, the measurement is performed using the method described in the examples below.

[0088] The adhesive sheet having the aforementioned total transmittance and haze value can be a colored transparent or colorless transparent adhesive sheet. It should be noted that in this specification, "transparent" is used to include the concept of translucency. Furthermore, the optical distortion reduction effect achieved by the adhesive sheet utilizing the technology disclosed herein can be achieved by a configuration in which at least a portion of the adhesive sheet surface has a level of transmittance sufficient for visual recognition through the adhesive sheet; therefore, the adhesive sheet does not need to be transparent or translucent.

[0089] (Adhesion to glass)

[0090] The adhesive force of the adhesive sheet disclosed herein is not particularly limited and can be set according to the target. In several ways, the adhesive force of the adhesive sheet to the glass plate (adhesive force to glass) is, for example, suitable to be about 1.0 N / 20 mm or more, and can be about 3.0 N / 20 mm or more (e.g., about 5.0 N / 20 mm or more). From the viewpoint of bonding reliability, the above-mentioned adhesive force to glass is preferably about 7.0 N / 20 mm or more, more preferably about 8.0 N / 20 mm or more, further preferably about 9.0 N / 20 mm or more, can be about 10.0 N / 20 mm or more, and can also be about 11.0 N / 20 mm or more. The adhesive sheet having the above-mentioned adhesive force to glass can be preferably used for purposes such as joining and fixing components. Furthermore, from the viewpoint of easily achieving a balance with other characteristics, the above-mentioned adhesive force to glass can 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 the glass can be adjusted by selecting the composition and thickness of the adhesive layer.

[0091] The adhesive strength of the glass was determined as follows: For the adhesive surface of the test object, a 2kg rubber roller was pressed against the glass plate once. At 23°C and 50%RH, a tensile testing machine was used to peel the adhesive sheet from the glass plate at a peel angle of 180 degrees and a tensile speed of 300mm / min, according to JIS Z 0237. The peel strength was then measured to determine the adhesive strength. Specifically, the method described in the following examples was used for determination.

[0092] (Elastic modulus based on tensile test)

[0093] In several preferred embodiments, the elastic modulus of the adhesive sheet based on a tensile test (also known as the initial elastic modulus) is 3.0 MPa or higher. Adhesive sheets with higher elastic modulus tend to exhibit better resistance to deformation. Such adhesive sheets with high elastic modulus are preferably used for purposes such as joining and fixing components. For example, in a method where two components are joined using an adhesive sheet, the high resistance to deformation of the adhesive sheet helps to maintain the relative position of the two components with good accuracy. Furthermore, in a method where a film component is joined to other components using an adhesive sheet, the high resistance to deformation of the adhesive sheet helps to suppress events that cause changes in the appearance of the laminate due to localized pressing from the film component side (resistance to pressing deformation). In methods where the adhered object is a rigid component with transparency (e.g., a glass component), suppressing changes in appearance visually perceived from the adhered object side is particularly meaningful.

[0094] In several preferred embodiments of the adhesive sheet, the aforementioned elastic modulus can 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. There is a tendency for increased elastic modulus to improve deformation resistance. There is no particular limitation on the upper limit of the aforementioned elastic modulus. From the viewpoint of easily achieving a balance with other properties (e.g., one or more properties selected from impact resistance, glass adhesion, haze value, etc.), an elastic modulus of 150 MPa or less is advantageous, preferably 120 MPa or less, and can be 100 MPa or less, 80 MPa or less, or 60 MPa or less. The aforementioned elastic modulus based on tensile testing can be adjusted by selecting the composition of the adhesive sheet (typically the adhesive layer), etc. The elastic modulus based on tensile testing is determined by the aforementioned tensile test. More specifically, it is determined by the method described in the embodiments described later.

[0095] (Impact resistance)

[0096] The adhesive sheet disclosed herein preferably has an impact resistance of 2.0 J / 10 mm. 2 The above describes how highly impact-resistant adhesive sheets can be used to form highly reliable bonds. This is an advantageous feature for adhesive sheets used, for example, for joining or fixing components. The adhesive sheet can withstand impacts such as drops or collisions, maintaining a good bond between the component and the adhered object.

[0097] In several preferred embodiments of the adhesive sheet, the aforementioned impact resistance can be, for example, 2.1 J / 10 mm. 2 The above, or 2.3J / 10mm 2 The above, or 2.5J / 10mm 2The above, or 2.7J / 10mm 2 The above, or 3.0J / 10mm 2 That's all. The adhesive sheet disclosed herein can also have the aforementioned impact resistance of 3.3 J / 10 mm. 2 or above 3.5J / 10mm 2 The above method is preferably implemented. There is no particular limitation on the upper limit of the impact resistance. From the viewpoint of easily achieving a balance with other properties, the impact resistance can, for example, be 20 J / 10 mm. 2 The following can also be 15J / 10mm 2 The following can also be 10J / 10mm 2 The following can also be 8.0J / 10mm 2 The following can also be 6.0J / 10mm 2 The impact resistance can be adjusted by selecting the composition and thickness of the adhesive layer. Impact resistance is determined by the shear impact test described above. More specifically, it is determined by the method described in the examples below.

[0098] (thickness)

[0099] The thickness of the adhesive sheet is appropriately set according to the intended use and application method, and is not limited to a specific range. For example, the thickness of the adhesive sheet can be approximately 1 μm to 500 μm, or approximately 3 μm to 500 μm. In several cases, a thickness of 5 μm or more is appropriate, for example, 10 μm or more, preferably 20 μm or more, more preferably 25 μm or more, and may also exceed 25 μm. In adhesive sheets with greater thickness, optical distortion is easily reduced due to the stress dispersion ability of the adhesive layer. Furthermore, adhesive sheets with greater thickness tend to have excellent height difference tracking properties and easily absorb deformation caused by foreign objects. Impact resistance also tends to be improved. The technology disclosed herein is preferably implemented with an adhesive sheet thickness of 30 μm or more. The thickness of the aforementioned adhesive sheet can 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 sheet increases, the light path through the adhesive sheet also becomes longer, thus making the optical distortion easier to visually detect. Therefore, in several ways, it is appropriate to set the thickness of the adhesive sheet to be less than 200 μm, for example, less than 150 μm, less than 120 μm, less than 100 μm, less than 70 μm, less than 50 μm, or less than 35 μm.

[0100] <Adhesive layer>

[0101] In the technology disclosed herein, the type of adhesive constituting the adhesive layer in the adhesive sheet is not particularly limited. The adhesive layer may, for example, be an adhesive layer comprising one or more adhesives selected from a variety of known adhesives, such as acrylic adhesives, rubber adhesives (natural rubber, synthetic rubber, mixtures thereof, etc.), silicone adhesives, polyester adhesives, urethane adhesives, polyether adhesives, polyamide adhesives, and fluorinated adhesives. Here, acrylic adhesives refer to adhesives based on acrylic polymers (the main component of the polymer composition, i.e., a component with a content exceeding 50% by weight). The same meaning applies to rubber adhesives and other adhesives.

[0102] (Polymer (A))

[0103] In several ways, the adhesive layer described above contains a polymer (A). Examples of materials that can be used as polymer (A) include acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, fluoropolymers, and other polymers known in the field of adhesives that exhibit rubber elasticity in the room temperature range. They can be used alone or in combination of two or more.

[0104] From the viewpoint of adhesive properties such as impact resistance, it is appropriate for the polymer (A) to account for 40% or more of the total weight of the adhesive layer, preferably 50% or more, more preferably 60% or more, further preferably 70% or more, and it can be about 80% or more, about 90% or more, or about 97% or more (e.g., about 99% or more). When using an adhesive with a high proportion of polymer (A), there is a tendency for excellent transparency. In addition, it is representative for the polymer (A) to account for less than 100% of the total weight of the adhesive layer. From the viewpoint of easily adjusting the balance of properties, it is advantageous for it to be 95% or less, preferably 92% or less, and it can be 90% or less or 87% or less.

[0105] As a preferred example of polymer (A), an acrylic polymer can be cited. The adhesive layer in the technology disclosed herein can be an acrylic adhesive layer containing an acrylic polymer as the base polymer (the main component of the polymer composition, i.e., a component with a content exceeding 50% by weight). Acrylic adhesives are preferred from the viewpoints of transparency and weather resistance, and they readily achieve viscoelastic properties with excellent impact resistance without heavily relying on additives such as softeners. The acrylic polymer as polymer (A) (hereinafter sometimes referred to as "acrylic polymer (A)") is preferably an acrylic polymer composed of a monomer component comprising a (meth)acrylate alkyl ester having a straight-chain or branched alkyl group having 1 or more and 20 or fewer carbon atoms at the ester terminus. Hereinafter, (meth)acrylate alkyl esters having an alkyl group having X or more and 9 or fewer carbon atoms at the ester terminus are sometimes referred to as "(meth)acrylate C". X-Y Alkyl esters.

[0106] Among several approaches, from the perspective of easily achieving a balance of properties, the monomer component of acrylic polymer (A) as a whole contains (meth)acrylic acid C. 1-20 The proportion of alkyl esters is appropriate to be more than 40% by weight, for example, it can be more than 45% by weight, more than 50% by weight, more than 55% by weight, or more than 60% by weight. Among the monomer components, (meth)acrylic acid C... 1-20 The proportion of alkyl esters can be 100% by weight, but from the perspective of easily achieving a balance of properties, 98% by weight or less is appropriate, for example, 95% by weight or less, or 90% by weight or less. In several ways, from the viewpoint of improving the cohesiveness of the adhesive layer, the total monomer composition of the acrylic polymer (A) contains (meth)acrylic acid C. 1-20 The proportion of alkyl esters can be, for example, less than 85% by weight, less than 80% by weight, less than 75% by weight, less than 70% by weight, less than 65% by weight, or less than 60% by weight.

[0107] As (meth)acrylic acid C 1-20Non-limiting specific examples of alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, and so on. Nonyl acrylate, isononyl acrylate, decyl acrylate, isodecyl acrylate, undecyl acrylate, dodecyl acrylate, tridecyl acrylate, tetradecyl acrylate, pentadecyl acrylate, hexadecyl acrylate, heptadecanyl acrylate, stearyl acrylate, isostearyl acrylate, nonadecanyl acrylate, eicosyl acrylate, etc.

[0108] Among them, it is preferred to use at least (meth)acrylic acid C. 4-20 Alkyl esters, more preferably using at least (meth)acrylic acid C 4-18 Alkyl esters. C(meth)acrylate is a particularly preferred option. 4-18 Alkyl esters, such as n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA), are preferred. 4-20 Other specific examples of alkyl esters include isononyl acrylate, n-butyl methacrylate (BMA), 2-ethylhexyl methacrylate (2EHMA), and isostearyl acrylate (iSTA). These (meth)acrylates... 4-20 Alkyl esters can be used alone or in combination of two or more.

[0109] The aforementioned monomeric components preferably include at least one or both of, for example, n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA). In several embodiments, the aforementioned monomeric components preferably include at least BA. Examples of monomeric components that include at least BA include: monomeric components comprising BA but not 2EHA, and monomeric components comprising BA and 2EHA in a content of less than the content of BA (e.g., the content of 2EHA is less than 0.5 times or less than 0.3 times the content of BA).

[0110] In several ways, the monomer components constituting the acrylic polymer (A) may include (meth)acrylic acid C in a proportion of 40% by weight or more. 4-18 Alkyl ester. (Meth)acrylic acid C in the monomer component. 4-18The proportion of alkyl esters can be, for example, 50% or more by weight, 60% or more by weight, or 65% or more by weight.

[0111] Furthermore, from the viewpoint of improving the cohesiveness of the adhesive layer, the monomer component (meth)acrylic acid C 4-18 It is appropriate for the proportion of alkyl esters to be 99.5% by weight or less, but it can be 95% by weight or less, 85% by weight or less, or 75% by weight or less.

[0112] The monomer components constituting the acrylic polymer (A) may, along with the alkyl methacrylate, include other monomers (copolymeric monomers) that can copolymerize with the alkyl methacrylate, as needed. Suitable copolymeric monomers include monomers with polar groups (e.g., carboxyl, hydroxyl, nitrogen-containing rings, etc.) and monomers with relatively high glass transition temperatures (e.g., above 10°C) in homopolymers. Monomers with polar groups can help introduce crosslinking points into the acrylic polymer (A) or improve the cohesive strength of the adhesive. One copolymeric monomer may be used alone or in combination of two or more.

[0113] The following monomers can be listed as non-limiting examples of copolymerizable monomers.

[0114] Carboxyl-containing monomers: such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc.

[0115] Monomers containing anhydride groups: for example, maleic anhydride and itaconic anhydride.

[0116] Hydroxyl-containing monomers: for example, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 6-hydroxyhexyl methacrylate, 8-hydroxyoctyl methacrylate, 10-hydroxydecyl methacrylate, 12-hydroxylaurate methacrylate, methyl methacrylate (4-hydroxymethylcyclohexyl) methacrylate, etc., hydroxyalkyl methacrylates, etc.

[0117] Monomers containing sulfonic acid or phosphoric acid groups: for example, styrene sulfonic acid, allyl sulfonic acid, sodium vinyl sulfonate, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamide propanesulfonic acid, (meth)acrylate sulfonyl propane, (meth)acryloyloxynaphthalene sulfonic acid, 2-hydroxyethylacryloyl phosphate, etc.

[0118] Epoxy-containing monomers: For example, glycidyl acrylate (meth)acrylate, 2-ethyl glycidyl ether (meth)acrylate and other epoxy-containing acrylates, allyl glycidyl ether, glycidyl ether (meth)acrylate, etc.

[0119] Cyano-containing monomers: for example, acrylonitrile, methacrylonitrile, etc.

[0120] Monomers containing isocyanate groups: for example, ethyl 2-isocyanate of (meth)acrylate, etc.

[0121] Amide-containing monomers: such as (meth)acrylamide; N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N,N-dipropyl (meth)acrylamide, N,N-diisopropyl (meth)acrylamide, N,N-di-n-butyl (meth)acrylamide, N,N-di-tert-butyl (meth)acrylamide, etc.; N-alkyl (meth)acrylamides such as N-ethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-butyl (meth)acrylamide, N-n-butyl (meth)acrylamide, etc.; N-vinylacetamide and other N-vinylcarboxylic acid amides; monomers with hydroxyl and amide groups, such as N-(2-hydroxyethyl)(methyl)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 alkoxy and amide groups, such as N-methoxymethyl (meth)acrylamide, N-methoxyethyl (meth)acrylamide, and N-butoxymethyl (meth)acrylamide; and N-alkoxyalkyl (meth)acrylamides, such as N,N-dimethylaminopropyl (meth)acrylamide and N-(meth)acryloylmorpholine.

[0122] Amino-containing monomers: such as aminoethyl methacrylate, N,N-dimethylaminoethyl methacrylate, and tert-butylaminoethyl methacrylate.

[0123] Monomers with epoxy groups: for example, glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, and allyl glycidyl ether.

[0124] Monomers having a nitrogen-containing ring: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrrazine, N-vinylpyrrole, N-vinylimidazolium, 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-vinylisooxazole, N-vinylthiazole, N-vinylisothiazole, N-vinylpyridazine, etc. (e.g., N-vinyl-2-caprolactam and other lactams).

[0125] Monomers having a succinimide skeleton: for example, N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, N-(meth)acryloyl-8-oxyhexamethylenesuccinimide, etc.

[0126] Maleimides: For example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, etc.

[0127] Itaconimides: For example, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide, etc.

[0128] Aminoalkyl esters of (meth)acrylate: for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, and tert-butylaminoethyl (meth)acrylate.

[0129] Alkoxy-containing monomers: for example, alkoxyalkyl esters of (meth)acrylates such as 2-methoxyethyl acrylate, 3-methoxypropyl acrylate, 2-ethoxyethyl acrylate, propoxyethyl acrylate, butoxyethyl acrylate, ethoxypropyl acrylate, etc.; alkoxyalkylene glycol (meth)acrylates such as methoxyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, etc. (e.g., alkoxypolyalkylene glycol (meth)acrylate).

[0130] Alkoxysilyl monomers: such as 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane and other alkoxysilyl-containing (meth)acrylates, vinyltrimethoxysilane, vinyltriethoxysilane and other alkoxysilyl-containing vinyl compounds, etc.

[0131] Vinyl esters: such as vinyl acetate, vinyl propionate, etc.

[0132] Vinyl ethers: For example, vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether.

[0133] Aromatic vinyl compounds: for example, styrene, α-methylstyrene, vinyltoluene, etc.

[0134] Olefins: such as ethylene, butadiene, isoprene, isobutene, etc.

[0135] (Meth)acrylates containing alicyclic hydrocarbon groups: for example, cyclopentyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, dicyclopentyl methacrylate, adamantane methacrylate, etc.

[0136] (Meth)acrylates containing aromatic hydrocarbon groups: for example, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, and other (meth)acrylates containing aromatic hydrocarbon groups.

[0137] In addition, there are heterocyclic (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate, halogen-containing (meth)acrylates such as those containing vinyl chloride or fluorine atoms, silicon-containing (meth)acrylates such as organosilicon (meth)acrylates, and (meth)acrylates derived from alcohols derived from terpene compounds.

[0138] When using this type of comonomer, there is no particular limitation on its amount; setting it to 0.01% by weight or more of the total monomer component is appropriate. From the viewpoint of better utilizing the comonomer, the amount of comonomer can be set to 0.1% by weight or more of the total monomer component, or even 0.5% by weight or more. Furthermore, from the viewpoint of easily achieving a balance of adhesive properties, setting the amount of comonomer to 50% by weight or less of the total monomer component is appropriate, and preferably 40% by weight or less.

[0139] In several ways, the monomer component constituting the acrylic polymer (A) may include a monomer having nitrogen atoms. By using a monomer having nitrogen atoms, the cohesive force of the adhesive can be improved, and preferably the peel strength after photocuring can be improved. As a preferred example of a monomer having nitrogen atoms, a monomer having a nitrogen-containing ring can be listed. As a monomer having a nitrogen-containing ring, monomers such as those described above can be used, for example, an N-vinyl cyclic amide represented by general formula (1) can be used.

[0140]

[0141] Here, in general formula (1), R 1 It is a divalent organic group, specifically -(CH2). n - n is an integer from 2 to 7 (preferably 2, 3 or 4). N-vinyl-2-pyrrolidone is preferably used. Other preferred examples of monomers having a nitrogen atom include (meth)acrylamide.

[0142] The amount of the monomer containing nitrogen atoms (preferably a monomer containing a nitrogen-containing ring) is not particularly limited; for example, it can be 1% or more, 3% or more, 5% or more, or 7% or more of the total monomer component. In some embodiments, the amount of the monomer containing nitrogen atoms can be 10% or more, 15% or more, or 20% or more of the total monomer component. Furthermore, it is appropriate to set the amount of the monomer containing nitrogen atoms to be, for example, 40% or less of the total monomer component; it can be 35% or less, 30% or less, or 25% or less. In several other embodiments, the amount of the monomer containing nitrogen atoms can be, for example, 20% or less, or 15% or less of the total monomer component.

[0143] In several embodiments, the monomeric component constituting the acrylic polymer (A) may include a hydroxyl-containing monomer. By using a hydroxyl-containing monomer, the cohesive strength and degree of crosslinking (e.g., crosslinking based on isocyanate crosslinking agents) of the adhesive can be appropriately adjusted. There are no particular limitations on the amount of hydroxyl-containing monomer used; for example, it can be 0.01% by weight or more, 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 of the total monomer component. Furthermore, from the viewpoint of suppressing the water absorption of the adhesive layer, in several embodiments, it is appropriate to set the amount of hydroxyl-containing monomer to, for example, 40% by weight or less of the total monomer component; it can be set to 30% by weight or less, 25% by weight or less, or 20% by weight or less. In other embodiments, the amount of hydroxyl-containing monomer can be set to, for example, 15% by weight or less, 10% by weight or less, or 5% by weight or less of the total monomer component.

[0144] In several ways, the proportion of carboxyl-containing monomers in the monomer component of the acrylic polymer (A) may be, for example, less than 2% by weight, less than 1% by weight, or less than 0.5% by weight (e.g., less than 0.1% by weight). Carboxyl-containing monomers may also be substantially not used as a monomer component of the acrylic polymer (A). Here, "substantially not using carboxyl-containing monomers" means, at least, that carboxyl-containing monomers are not intentionally used. An adhesive layer comprising the acrylic polymer (A) with the amount of carboxyl-containing monomers limited as described above is preferred from the viewpoint of preventing metal corrosion. Adhesive sheets having said adhesive layer are also preferably used, for example, in a manner where the adhesive layer contacts an adherend having a metallic material.

[0145] In several embodiments, the monomer component constituting the acrylic polymer (A) may include a (meth)acrylate containing an alicyclic hydrocarbon group. This improves the cohesive strength of the adhesive and enhances the peel strength after photocuring. Substances such as those described above that contain an alicyclic hydrocarbon group and are used as (meth)acrylates can be preferred, for example, cyclohexyl acrylate and isobornyl acrylate. There is no particular limitation on the amount of (meth)acrylate containing an alicyclic hydrocarbon group used; for example, it can be set to 1% or more, 3% or more, or 5% or more of the total monomer component. In several embodiments, the amount of (meth)acrylate containing an alicyclic hydrocarbon group can be 10% or more, or 15% or more of the total monomer component. Setting the upper limit of the amount of (meth)acrylate containing an alicyclic hydrocarbon group to about 40% or less is appropriate; for example, it can be 30% or less, or 25% or less (e.g., 15% or less, and further 10% or less).

[0146] There are no particular limitations on the polymerization method used to form (synthesize) polymer (A) from monomer components, and various existing and well-known polymerization methods can be appropriately employed. For example, suitable methods include thermal polymerization such as solution polymerization, emulsion polymerization, and bulk polymerization (typically carried out in the presence of a thermal polymerization initiator); photopolymerization by irradiation with ultraviolet light (typically carried out in the presence of a photopolymerization initiator); and radiation polymerization by irradiation with beta rays, gamma rays, etc. Two or more polymerization methods can also be combined (e.g., stepwise).

[0147] As a solvent for solution polymerization (polymerization solvent), for example, any one or a mixture of two or more solvents can be used, selected from aromatic compounds such as toluene (representative aromatic hydrocarbons); esters such as ethyl acetate and butyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; haloalkanes such as 1,2-dichloroethane; lower alcohols such as isopropanol (e.g., monohydric alcohols with 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether; ketones such as methyl ethyl ketone.

[0148] During polymerization, depending on the polymerization method and process, known or commonly used thermal polymerization initiators or photopolymerization initiators can be used. One such initiator can be used alone, or two or more can be used in combination.

[0149] While there are no particular limitations, azo polymerization initiators, peroxide initiators, redox initiators obtained from combinations of peroxides and reducing agents, and substituted ethane initiators can be used. More specifically, examples include azo-based initiators such as 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2-methylpropanediamine) disulfate, 2,2'-azobis(2-amidinepropane) dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis(N,N'-dimethyleneisobutylamidine), and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropanediamine] hydrate; persulfates such as potassium persulfate and ammonium persulfate; peroxide-based initiators such as benzoyl peroxide, tert-butyl hydroperoxide, and hydrogen peroxide; substituted ethane-based initiators such as phenyl-substituted ethane; and redox initiators such as combinations of persulfates and sodium bisulfite, and combinations of peroxides and sodium ascorbate, but are not limited to these. Thermal polymerization can preferably be carried out at temperatures of around 20 to 100°C (typically 40 to 80°C), but is not limited thereto.

[0150] While there are no particular limitations, photopolymerization initiators such as ketal photopolymerization initiators, acetophenone photopolymerization initiators, benzoin ether photopolymerization initiators, acylphosphine oxide photopolymerization initiators, α-keto alcohol photopolymerization initiators, aromatic sulfonyl chloride photopolymerization initiators, photoactive oxime photopolymerization initiators, benzoin photopolymerization initiators, benzoyl photopolymerization initiators, benzophenone photopolymerization initiators, and thioxanone photopolymerization initiators can be used.

[0151] The amount of polymerization initiator used can be the usual amount corresponding to the polymerization method and polymerization mode, without any particular limitation. For example, relative to 100 parts by weight of the monomer to be polymerized, about 0.001 to 5 parts by weight of polymerization initiator can be used (typically about 0.01 to 2 parts by weight, for example about 0.01 to 1 part by weight).

[0152] In the above polymerization, various known chain transfer agents (which can also be understood as molecular weight regulators or degree of polymerization regulators) can be used as needed. As chain transfer agents, thiols such as n-dodecyl mercaptan, tert-dodecyl mercaptan, mercaptoacetic acid, and α-thioglycerol can be used. Alternatively, chain transfer agents without sulfur atoms (non-sulfur chain transfer agents) can also be used. Specific examples of non-sulfur chain transfer agents include anilines such as N,N-dimethylaniline and N,N-diethylaniline; terpenes such as α-pinene and terpinene; styrene compounds such as α-methylstyrene and α-methylstyrene dimers; compounds containing benzyl groups such as dibenzylidene acetone, cinnamyl alcohol, and cinnamaldehyde; hydroquinones such as hydroquinone and naphthol; quinones such as benzoquinone and naphthoquinone; alkenes such as 2,3-dimethyl-2-butene and 1,5-cyclooctadiene; alcohols such as phenol, benzyl alcohol, and allyl alcohol; and benzyl hydrogen compounds such as diphenylbenzene and triphenylbenzene. Chain transfer agents can be used alone or in combination of two or more. It should be noted that the techniques disclosed herein can also be preferably implemented without the use of chain transfer agents.

[0153] The amount of chain transfer agent used relative to 100 parts by weight of the monomer component can be set to, for example, about 0.005 parts by weight to 1 part by weight. In several embodiments, from the viewpoint of impact resistance, the amount of chain transfer agent relative to 100 parts by weight of the monomer component can be, for example, 0.01 parts by weight or more, 0.03 parts by weight or more, 0.05 parts by weight or more, or 0.07 parts by weight or more. Furthermore, in several embodiments, from the viewpoint of deformation resistance, the amount of chain transfer agent relative to 100 parts by weight of the monomer component can be, for example, 0.5 parts by weight or less, 0.2 parts by weight or less, 0.1 parts by weight or less, or even less than 0.1 parts by weight (for example, 0.09 parts by weight or less).

[0154] In the technology disclosed herein, the glass transition temperature (Tg) of polymer (A) is not particularly limited; less than 0°C is suitable, less than -10°C is preferred, and less than -20°C is even more desirable. By lowering the Tg of polymer (A), there is a tendency to improve the aforementioned impact resistance. In several embodiments, the Tg of polymer (A) may be less than -25°C or less than -30°C. Furthermore, the Tg of polymer (A) is typically -80°C or higher, for example, it may be -70°C or higher, -60°C or higher, or -55°C or higher. From the viewpoint of improving the aforementioned elastic modulus, in several embodiments, the Tg of 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.

[0155] In this specification, the Tg of a polymer refers to the Tg calculated using the Fox formula based on the composition of the monomers used in the preparation of the polymer. The Fox formula, as shown below, expresses the relationship between the Tg of the copolymer and the glass transition temperature Tgi of the homopolymer formed by homopolymerizing the monomers constituting the copolymer.

[0156] 1 / Tg = Σ(Wi / Tgi)

[0157] In the Fox formula above, Tg represents the glass transition temperature of the copolymer (in K), Wi represents the weight fraction of monomer i in the copolymer (weight-based copolymerization ratio), and Tgi represents the glass transition temperature of the homopolymer of monomer i (in K). When the polymer to which Tg is to be determined is a homopolymer, the Tg of the homopolymer is consistent with the Tg of the polymer to which Tg is to be determined.

[0158] The glass transition temperature (Tg) of the homopolymer used in the calculation is the value recorded in known sources. For example, for the monomers listed below, the following values ​​are used as the glass transition temperature of the homopolymer of that monomer.

[0159] n-Butyl acrylate -55℃

[0160] 2-Ethylhexyl acrylate -70℃

[0161] Isostearyl acrylate -18℃

[0162] Cyclohexyl acrylate 15℃

[0163] N-Vinyl-2-pyrrolidone 54℃

[0164] 2-Hydroxyethyl Acrylate -15℃

[0165] 4-Hydroxybutyl acrylate -40℃

[0166] For the glass transition temperatures of homopolymers of monomers other than those in the examples above, the values ​​described in the "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) are used. In cases where multiple values ​​are described in this document, the highest value is used.

[0167] The weight-average molecular weight (Mw) of polymer (A) is not particularly limited. From the viewpoint of achieving a more balanced combination of deformation resistance and impact resistance, in several ways, the Mw of polymer (A) is, for example, about 10 × 10⁻⁶. 4 The above is appropriate and preferred, exceeding 20×10 4 It can exceed 30×10 4 It can also exceed 40×10 4 It can also exceed 50×10 4 Additionally, the upper limit of Mw for polymer (A) can be approximately 500 × 10⁻⁶. 4 Below. From the viewpoint of adhesion and peel strength of the adhered materials, in several ways, the Mw of polymer (A) can be, for example, 300 × 10. 4 The following can also be 150×10 4 The following can also be 100×10 4 The following can also be 90×10 4 The following can also be 75×10 4 the following.

[0168] The example of Mw described above can also be applied to the Mw of polymer (A) in the adhesive layer of the adhesive sheet disclosed herein, and can also be applied to the Mw of polymer (A) in the adhesive composition used to form the adhesive layer.

[0169] It should be noted that Mw refers to the value converted from standard polystyrene obtained by gel permeation chromatography (GPC). As the GPC apparatus, for example, the model name "HLC-8220GPC" (manufactured by Tosoh Corporation) or its equivalent can be used. As the determination conditions for GPC, the following methods can be employed, for example. In the examples described below, Mw was determined by the following method.

[0170] (GPC measurement conditions)

[0171] Device: Made by Tosoh Corporation, HLC-8220GPC

[0172] column:

[0173] Sample column; manufactured by Tosoh Corporation, TSKguardcolumn Super HZ-H (1 piece) + TSKgel SuperHZM-H (2 pieces)

[0174] Reference column; Tosoh Corporation, TSKgel Super H-RC (1 column)

[0175] Flow rate: 0.6 mL / min

[0176] Injection volume: 10 μL

[0177] Column temperature: 40℃

[0178] Elution buffer: THF

[0179] Injected sample concentration: 0.2% by weight

[0180] Detector: Differential refractometer

[0181] The weight-average molecular weight is calculated using polystyrene conversion.

[0182] (Photoreactive monomer (B))

[0183] In several preferred embodiments, the adhesive layer may contain a photoreactive monomer (B) in addition to the polymer (A) described above (e.g., an acrylic polymer (A)). The photoreactive monomer (B) may be a compound containing 2 or more olefinic unsaturated groups (hereinafter also referred to as "functional group number"). There is no particular upper limit on the number of functional groups of the compound used as the photoreactive monomer (B). The number of functional groups may be, for example, 50 or less, 40 or less, 30 or less, 20 or less, or 15 or less. In several embodiments, compounds with olefinic unsaturated groups having, for example, 2 to 10 functional groups may be used; compounds with 2 to 8 functional groups are preferred; and compounds with 2 to 6 functional groups are more preferred. One photoreactive monomer (B) may be used alone or in combination of two or more.

[0184] The photoreactive monomer (B) contained in the adhesive layer can react with the olefinic unsaturated groups to form a cross-linked structure after being bonded to the substrate by light (e.g., ultraviolet light). Adhesive sheets containing the photoreactive monomer (B) in the adhesive layer can have their adhesive layer cured by ultraviolet light or similar methods after being bonded to the substrate, thereby improving the deformation resistance of the adhesive layer. Thus, it is possible to suitably combine good conformability to the surface shape of the substrate during bonding with high deformation resistance after bonding.

[0185] Examples of the aforementioned olefinic unsaturated groups include acryloyl, methacryloyl, vinyl, and allyl, but are not limited to these. The photoreactive monomer (B) may have two or more olefinic unsaturated groups within its molecule that are identical or different groups. Acryloyl and methacryloyl are examples of olefinic unsaturated groups preferred from the viewpoint of photoreactivity. Acryloyl is preferred.

[0186] The functional group equivalent of the compound used as the photoreactive monomer (B) is not particularly limited. For example, the functional group equivalent can be about 50-10000 g / mol, about 50-8000 g / mol, about 50-5000 g / mol, about 50-3000 g / mol, or about 50-2000 g / mol. In several embodiments, from the viewpoint of photocurability, compounds with a functional group equivalent of about 60-800 g / mol (more preferably about 80-600 g / mol) are preferred as the photoreactive monomer (B).

[0187] It should be noted that 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 olefinic unsaturated functional groups possessed by the photoreactive monomer (B). The molecular weight of the photoreactive monomer (B) can be obtained, for example, by the GPC method, in the form of weight-average molecular weight converted to standard polystyrene. Alternatively, the molecular weight [g / mol] of the photoreactive monomer (B) can also be the manufacturer's nominal value or the molecular weight calculated from the molecular structure.

[0188] The molecular weight of the photoreactive monomer (B) is not particularly limited and can be selected in a manner suitable for achieving the desired effect. For example, a monomer with a molecular weight of about 20,000 or less can be used as the photoreactive monomer (B). From the viewpoint of ease of preparation and coatability of the adhesive composition, the molecular weight of the photoreactive monomer (B) can be, for example, 16,000 or less, 10,000 or less, 4,000 or less, 1,500 or less, or 1,000 or less in several ways. The molecular weight of the photoreactive monomer (B) can be, for example, 100 or more, and representatively 120 or more. From the viewpoint of processability and handleability of the adhesive sheet, the molecular weight of the photoreactive monomer (B) can 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 in several ways.

[0189] In the adhesive sheet disclosed herein, the amount of photoreactive monomer (B) contained in the adhesive layer is not particularly limited and can be appropriately set according to the target performance (e.g., the elastic modulus of the adhesive layer after photocuring). Among several ways in which the adhesive layer comprises a polymer (A) and a photoreactive monomer (B), the amount of photoreactive monomer (B) relative to 100 parts by weight of the polymer (A) contained in the adhesive layer can be, for example, 1 part by weight or more, or 3 parts by weight or more. From the viewpoint of easily improving the elastic modulus of the adhesive layer after photocuring, the amount of photoreactive monomer (B) relative to 100 parts by weight of the polymer (A) can be 5 parts by weight or more, or 10 parts by weight or more, or 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 processability (e.g., processability) of the adhesive sheet, it is appropriate to set the amount of photoreactive monomer (B) to 80 parts by weight or less relative to 100 parts by weight of polymer (A), preferably to 60 parts by weight or less, and it can be 50 parts by weight or less, or 40 parts by weight or less, or 35 parts by weight or less.

[0190] In several embodiments, the adhesive layer preferably contains at least compound B1, which has an intramolecular ring structure and two or more olefinic unsaturated groups, as the photoreactive monomer (B). When using an adhesive layer containing compound B1 with this structure, the deformation resistance of the adhesive layer can be effectively improved by light irradiation. The ring in the ring structure can be an aliphatic ring or an aromatic ring. Furthermore, the ring can be a carbocyclic ring or a heterocyclic ring. The number of rings contained in one molecule of compound B1 can be one or more. There is no particular upper limit to the number of rings contained in compound B1; for example, it can be less than 100, less than 70, less than 50, less than 30, less than 15, less than 8, less than 6, less than 5, or less than 4. When compound B1 contains two or more rings, these rings can form fused rings (typically bicyclic or tricyclic fused rings) or not. The rings are preferably contained in the main chain of compound B1. Preferably, one olefinic unsaturated group of compound B1 is linked to at least one other olefinic unsaturated group via the aforementioned ring structure. Compound B1 can be used alone or in combination with two or more other compounds.

[0191] As compound B1, compounds having a ring structure and two or more olefinic unsaturated groups within the molecule, and a functional group equivalent of 100 g / mol or more, are preferably used. When an adhesive sheet containing compound B1 with the aforementioned functional group equivalent in the adhesive layer is used, high deformation resistance and a bond with high impact resistance can be appropriately formed. While not specifically limiting, it can be understood that when compound B1 is used, the rigidity of the ring structure effectively increases the elastic modulus of the adhesive layer after light irradiation, imparting deformation resistance. On the other hand, the specified or higher functional group equivalent of compound B1 maintains the distance between crosslinking points, forming a crosslinked structure with high impact resistance. In several embodiments, the functional group equivalent of compound B1 can 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. Increasing the functional group equivalent of compound B1 tends to improve impact resistance. Furthermore, the functional group equivalent of compound B1 can be, for example, 10000 g / mol or less, 8000 g / mol or less, 5000 g / mol or less, 3000 g / mol or less, or 2000 g / mol or less. In several embodiments, from the viewpoint of photocurability, the functional group equivalent of compound B1 is preferably 800 g / mol or less, more preferably 600 g / mol or less. In several embodiments, the functional group equivalent of compound B1 can be 500 g / mol or less, 400 g / mol or less, or 300 g / mol or less.

[0192] In several embodiments, the number of functional groups in compound B1 can be, for example, 2 to 50, 2 to 40, 2 to 30, or 2 to 10, preferably 2 to 6, 2 to 4, or 2 to 3. In several embodiments, compound B1 with 2 functional groups is preferred.

[0193] Compound B1 may also have functional groups other than olefinic unsaturated groups. Examples of functional groups other than olefinic unsaturated groups include hydroxyl, carboxyl, and amino groups. Preferred examples of functional groups other than olefinic unsaturated groups include hydroxyl and amino groups.

[0194] Examples of compound B1 include bisphenol A type epoxy (meth)acrylates such as bisphenol A glycidyl ether (meth)acrylate adduct, bisphenol A glycidylamine (meth)acrylate adduct, and bisphenol A glycidyl ester (meth)acrylate adduct; epoxy alkyl ester 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; and bisphenol F type epoxy (meth)acrylates such as bisphenol F glycidyl ether (meth)acrylate adduct, bisphenol F glycidylamine (meth)acrylate adduct, and bisphenol F glycidyl ester (meth)acrylate adduct. EO-modified bisphenol F di(meth)acrylate, PO-modified bisphenol F di(meth)acrylate, and other epoxy-modified bisphenol F (meth)acrylates; bisphenol E type epoxy (meth)acrylates such as bisphenol E glycidyl ether (meth)acrylate adduct, bisphenol E glycidylamine (meth)acrylate adduct, and bisphenol E glycidyl ester (meth)acrylate adduct; EO-modified bisphenol E di(meth)acrylate, PO-modified bisphenol E di(meth)acrylate, and other epoxy-modified bisphenol E (meth)acrylates; 9,9-bis(4-hydroxyphenyl)fluorene di(meth)acrylate, 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene di(meth)acrylate... (Meth)acrylates containing a fluorene backbone, such as acrylates; (meth)acrylates with aliphatic rings (which may be alicyclic fused rings), such as tricyclodecanediethanol 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-cyclohexanediethanol diglycidyl ether (meth)acrylate; (meth)acrylate adducts of phenolic varnish type epoxy resins; (meth)acrylate adducts of thioether type epoxy resins; and (meth)acrylate adducts of naphthalene type epoxy resins. Acrylic acid adducts; (meth)acrylic acid adducts of dicyclopentadiene-type epoxy resins; (meth)acrylic acid adducts of alkyl diphenol-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; and modified forms of any of the above materials (e.g., amine modified forms, acid modified forms, halogen modified forms), etc., but not limited to them. In several embodiments, compound B1 having an aromatic carbocyclic ring may be preferred. Preferred examples of compound B1 include bisphenol A type epoxy (meth)acrylates, epoxy alkyl modified bisphenol A (meth)acrylates, and their modifiers (e.g., amine modifiers), as well as compounds containing the bisphenol A structure.

[0195] Commercially available products that can be used as compound B1 include, but are not limited to, products manufactured by Shin-Nakamura Chemical Industry Co., Ltd. under the trade names "A-DCP" and "A-BPE-4", Osaka Organic Chemical Industry Co., Ltd. under the trade names "Viscoat #540" and "Viscoat #700HV", Nippon Kayaku Co., Ltd. under the trade name "R-114F", Kyoeisha Chemical Co., Ltd. under the trade names "EpoxyEster 3000A" and "Epoxy Ester 80MFA", and DAICEL-ALLNEX LTD. under the trade names "EBECRYL 3700", "EBECRYL 3703", and "EBECRYL 3603".

[0196] 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 has both balanced deformation resistance and impact resistance, in several ways, the amount of compound B1 relative to 100 parts by weight of polymer (A) can 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 processability of the adhesive sheet, it is appropriate to set the amount of compound B1 relative to 100 parts by weight of polymer (A) to be 80 parts by weight or less, preferably 60 parts by weight or less, and can 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.

[0197] In several embodiments, the adhesive layer described above may contain compound B2, which has two or more functional groups and does not have an intramolecular ring structure, as the photoreactive monomer (B). Compound B2 is preferably used in combination with compound B1. This adjusts the crosslinking structure of the adhesive layer, resulting in a bond that is more suitable for both deformation resistance and impact resistance. Compound B2 may be used alone or in combination with two or more compounds.

[0198] The number of functional groups in compound B2 can be, for example, 50 or less, 40 or less, 30 or less, 20 or less, or 15 or less. In several embodiments, the number of functional groups in compound B2 can be, for example, 2 to 10, preferably 3 to 10, or 3 to 8, or 4 to 6. For example, in embodiments where a compound with 2 functional groups is used as compound B1, it becomes advantageous to use compound B2 with 3 or more functional groups (preferably 4 or more, more preferably 5 or more, and even more preferably 6 or more).

[0199] The functional group equivalent of compound B2 is not particularly limited, and can be, for example, less than 5000 g / mol, less than 2000 g / mol, or less than 1000 g / mol. In some embodiments, the functional group equivalent of compound B2 can be, for example, less than 600 g / mol. From the viewpoint of photocurability and improved hardness of the cured product, it can be less than 400 g / mol, less than 300 g / mol, less than 200 g / mol, less than 150 g / mol, or less than 100 g / mol. A representative functional group equivalent of compound B2 is 50 g / mol or more, preferably 60 g / mol or more, and can be 70 g / mol or more, 80 g / mol or more, or 90 g / mol or more.

[0200] 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, neopentyl glycol di(meth)acrylate with hydroxypentanoic acid, pentaerythritol di(meth)acrylate, allyl methacrylate, vinyl methacrylate, EO-modified and / or PO-modified versions of any of the above materials.

[0201] In the use of compound B2, the amount of compound B2 relative to 100 parts by weight of polymer (A) contained in the adhesive layer is not particularly limited, and can be set to 0.1 parts by weight or more, for example. From the viewpoint of easily obtaining an adhesive layer that has both balanced deformation resistance and impact resistance, in several methods, the amount of compound B2 relative to 100 parts by weight of polymer (A) can 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 the reduction of adhesion to the adherend caused by excessive crosslinking, in several methods, the amount of compound B2 relative to 100 parts by weight of polymer (A) is, for example, appropriate to be 25 parts by weight or less, preferably 17 parts by weight or less, 15 parts by weight or less, 13 parts by weight or less, or 9 parts by weight or less.

[0202] In the combination of compound B1 and compound B2, compound B2 is preferably a compound with 3 or more functional groups and a functional group equivalent that is smaller than that of compound B1. In several embodiments, the ratio of the functional group equivalent FE2 of compound B2 to the functional group equivalent FE1 of compound B1 (FE2 / FE1) can be, for example, 0.9 or less, 0.7 or less, 0.5 or less, or 0.4 or less. Using this method, the elastic modulus enhancement effect brought about by the photoreactive monomer (B) can be effectively utilized. The lower limit of the above ratio (FE2 / FE1) is not particularly limited, and can be, for example, 0.01 or more, 0.1 or more, or 0.2 or more.

[0203] In the combination of compound B1 and compound B2, the weight ratio (W2 / W1) of compound B2 (W2) to compound B1 (W1) is not particularly limited. In several embodiments, the weight ratio (W2 / W1) may be, for example, 0.05 to 10, 0.1 to 5, 0.2 to 3, or 0.3 to 2. By setting the weight ratio (W2 / W1) within any of the above ranges, there is a tendency to achieve the desired effect of the combination of compound B1 and compound B2.

[0204] In several other ways of using the photoreactive monomer (B) (representatively compound B2), the amount of photoreactive monomer (B) (representatively compound B2) can be set to about 3% by weight or less, preferably about 2% by weight or less, and more preferably about 1% by weight or less (e.g., about 0.5% by weight or less) of the monomer component of the polymer (A). The lower limit of the amount of photoreactive monomer (B) (representatively compound B2) used is only required to be greater than 0% by weight, and there is no particular limitation. Setting the amount of photoreactive monomer (B) (representatively compound B2) to about 0.001% by weight or more (e.g., about 0.01% by weight or more) of the monomer component is appropriate.

[0205] In several ways, the photoreactive monomer (B) can be included in the adhesive layer in a free form. The adhesive layer can be suitably formed using an adhesive composition that includes the photoreactive monomer (B) in a free form. Here, "free form" means that the photoreactive monomer (B) is not chemically bonded to other components (e.g., polymer (A)) contained in the adhesive layer or adhesive composition. Adhesive compositions that include the photoreactive monomer (B) in a free form are advantageous from the viewpoints of ease of preparation and gelation inhibition.

[0206] In several other forms, from the viewpoint of improving the processability of the adhesive sheet, at least a portion of the photoreactive monomer (B) can be included in the adhesive layer in a form that is chemically bonded to other components contained in the adhesive layer or adhesive composition (e.g., polymer (A), crosslinking agent, etc., described later). This chemical bonding can be, for example, a bond formed through a reaction between a functional group F1 (excluding olefinic unsaturated groups) present in the molecule of the photoreactive monomer (B) and a functional group F2 present in the molecule of the other components that can react with the aforementioned functional group F1. The other components can be crosslinking agents, with the photoreactive monomer (B) bonded to the polymer (A) by means of these crosslinking agents.

[0207] (Acrylic oligomers)

[0208] The adhesive layer of the adhesive sheet disclosed herein may contain acrylic oligomers from the viewpoint of improving cohesion and adhesion to surfaces adjacent to the adhesive layer (e.g., the surface of the supporting substrate in the adhesive sheet, the surface of the object to which the adhesive sheet is bonded). The adhesive layer containing the acrylic oligomers is preferably formed using an adhesive composition containing such acrylic oligomers. As the acrylic oligomers, it is preferable to use a substance with a higher Tg than the polymer (A) described above.

[0209] The temperature gradient (Tg) of the aforementioned acrylic oligomers is not particularly limited, and can be, for example, above about 20°C and below 300°C. The aforementioned Tg can be, for example, above about 30°C, above about 40°C, above about 60°C, above about 80°C, or above about 100°C. As the Tg of the acrylic oligomer increases, the effect of improving cohesive strength generally tends to increase. Furthermore, from the viewpoint of anchoring to the supporting substrate and shock absorption, the Tg of the acrylic oligomer can be, for example, below about 250°C, below about 200°C, below about 180°C, or below about 150°C. It should be noted that the Tg of the acrylic oligomer and the Tg of polymer (A) are both calculated based on the Fox formula.

[0210] The Mw of acrylic oligomers is not particularly limited; for example, it can be more than 1,000, more than 1,500, more than 2,000, or more than 3,000. Alternatively, the Mw of acrylic oligomers can be less than 30,000, less than 10,000, less than 7,000, or less than 5,000. When the Mw is within the above range, it is easy to achieve the effect of improving the cohesiveness of the adhesive layer and the adhesion to adjacent surfaces. The Mw of acrylic oligomers can be determined by GPC, expressed as a value converted from standard polystyrene. Specifically, for example, it can be determined using a TSKgelGMH-H (20) × 2 column in an HPLC 8020 manufactured by Tosoh Corporation, with tetrahydrofuran solvent at a flow rate of approximately 0.5 mL / min.

[0211] As monomeric components constituting acrylic oligomers, various (meth)acrylic acids C can be listed above. 1-20 Alkyl esters; various (meth)acrylates containing alicyclic hydrocarbon groups as described above; various (meth)acrylates containing aromatic hydrocarbon groups as described above; (meth)acrylate monomers such as (meth)acrylates derived from terpene compounds. They can be used alone or in combination of two or more.

[0212] From the viewpoint of improving adhesion, it is preferable that the acrylic oligomer contains acrylic monomers with a large-volume structure, such as isobutyl methacrylate and tert-butyl methacrylate, alkyl methacrylates with branched alkyl groups, alicyclic methacrylates, and aromatic methacrylates, as monomer units. Furthermore, when ultraviolet light is used during the synthesis of the acrylic oligomer and the preparation of the adhesive layer, monomers with saturated hydrocarbon groups at the ester terminus are preferred to minimize polymerization inhibition; for example, alkyl methacrylates with branched alkyl groups and methacrylates containing saturated alicyclic hydrocarbon groups can be suitable.

[0213] The proportion of (meth)acrylate monomers in the total monomer composition of the acrylic oligomer is typically more than 50% by weight, preferably more than 60% by weight, and more preferably more than 70% by weight (e.g., more than 80% by weight, and further more than 90% by weight). In several preferred embodiments, the acrylic oligomer is composed of monomers that are substantially composed of only one or more (meth)acrylate monomers. The monomer composition includes (meth)acrylates containing alicyclic hydrocarbon groups and (meth)acrylate C. 1-20 In the case of alkyl esters, their weight ratio is not particularly limited. In several ways, the ratio of (meth)acrylates containing alicyclic hydrocarbon groups to (meth)acrylate C is... 1-20The weight ratio of alkyl esters can be set to, for example, 10 / 90 or more, 20 / 80 or more, or 30 / 70 or more, and can be set to 90 / 10 or less, 80 / 20 or less, or 70 / 30 or less.

[0214] In addition to the aforementioned (meth)acrylate monomers, functionalized monomers may also be used as constituent monomers in acrylic oligomers, depending on the requirements. Examples of functionalized monomers include monomers with nitrogen-containing heterocycles such as N-vinyl-2-pyrrolidone and N-acryloylmorpholine; amino monomers such as N,N-dimethylaminoethyl methacrylate; amide monomers such as N,N-diethyl(meth)acrylamide; carboxyl monomers such as AA and MAA; and hydroxyl monomers such as 2-hydroxyethyl methacrylate. These functionalized monomers may be used individually or in combination of two or more. When using functionalized monomers, the proportion of functionalized monomers in the total monomer composition of the acrylic oligomer may be, for example, 1% or more by weight, 2% or more by weight, or 3% or more by weight, and may be, for example, 15% or less by weight, 10% or less by weight, or 7% or less by weight. Acrylic oligomers may also be produced without functionalized monomers.

[0215] Suitable acrylic oligomers include, for example, homopolymers of dicyclopentyl methacrylate (DCPMA), cyclohexyl methacrylate (CHMA), isobornyl methacrylate (IBXMA), isobornyl acrylate (IBXA), dicyclopentyl acrylate (DCPA), 1-adamantane methacrylate (ADMA), and 1-adamantane 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 acrylamide morpholine (ACMO), copolymers of CHMA and diethylacrylamide (DEAA), and copolymers of CHMA and AA.

[0216] Acrylic oligomers can be formed by polymerizing their constituent monomer components. There are no particular limitations on the polymerization method or mode; various well-known polymerization methods (e.g., solution polymerization, emulsion polymerization, bulk polymerization, photopolymerization, radiation polymerization, etc.) can be employed in a suitable manner. The types of polymerization initiators (e.g., azo polymerization initiators) that can be used as needed are basically as exemplified in the synthesis of acrylic polymer (A). The amount of polymerization initiator and the amount of optional chain transfer agent (e.g., thiols) are appropriately set according to common sense in order to achieve the desired molecular weight, and therefore detailed descriptions are omitted.

[0217] When the adhesive layer or adhesive composition contains acrylic oligomers, their content relative to 100 parts by weight of polymer (A) can be, for example, 0.01 parts by weight or more, and from the viewpoint of obtaining better results, it can be set to 0.05 parts by weight or more, or 0.1 parts by weight or more, or 0.2 parts by weight or more. Furthermore, from the viewpoint of compatibility with polymer (A), it is appropriate for the content of acrylic oligomers relative to 100 parts by weight of polymer (A) to be less than 50 parts by weight, preferably less than 30 parts by weight, more preferably 25 parts by weight or less, for example, it can be 10 parts by weight or less, or 5 parts by weight or less, or 1 part by weight or less. An adhesive layer or adhesive composition that does not contain acrylic oligomers may also be used.

[0218] (Cross-linking agent)

[0219] A crosslinking agent may be used in the adhesive layer as needed. In the adhesive sheet disclosed herein, the crosslinking agent is typically contained in the adhesive layer in a crosslinked form. By using the crosslinking agent, the cohesive strength of the adhesive layer can be appropriately adjusted. Furthermore, in an adhesive sheet containing a photoreactive monomer (B) in the adhesive layer, for example, by using the crosslinking agent and the photoreactive monomer (B) in combination, it is possible to appropriately combine the flexibility of the adhesive layer before photocuring of the aforementioned photoreactive monomer with the deformation resistance of the adhesive layer after photocuring.

[0220] There are no particular limitations on the type of crosslinking agent. For example, it can be selected from existing known crosslinking agents according to the composition of the adhesive composition, in a way that the crosslinking agent performs an appropriate crosslinking function within the adhesive layer. Examples of usable crosslinking agents 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. They can be used alone or in combination of two or more.

[0221] As isocyanate-based crosslinking agents, polyfunctional isocyanate compounds with two or more functions can be used. Examples include aromatic isocyanates such as toluene diisocyanate, xylene diisocyanate, polymethylene polyphenyl diisocyanate, tris(p-isocyanate phenyl)thiophosphate, and diphenylmethane diisocyanate; alicyclic isocyanates such as isophorone diisocyanate; and aliphatic isocyanates such as hexamethylene diisocyanate. Examples of commercially available products include trimethylolpropane / toluene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate L"), trimethylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate HL"), isocyanurate form of hexamethylene diisocyanate (manufactured by Tosoh Corporation, trade name "Coronate HX"), and trimethylolpropane / phenylenediamine diisocyanate adduct (manufactured by Mitsui Chemicals, trade name "Takenate D-110N"), among other isocyanate adducts.

[0222] As epoxy crosslinking agents, substances having two or more epoxy groups per molecule can be used without particular limitation. Epoxy crosslinking agents having three to five epoxy groups per molecule are preferred. Specific examples of epoxy crosslinking agents include N,N,N',N'-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, and polyglycerol polyglycidyl ether. Commercially available epoxy crosslinking agents include those manufactured under the trade names "TETRAD-X" and "TETRAD-C" by Mitsubishi Gas Chemical Co., Ltd., "Epichlone CR-5L" by DIC Co., Ltd., "DENACOL EX-512" by Nagase ChemteX Corporation, and "TEPIC-G" by Nissan Chemical Industries, Ltd.

[0223] As an oxazoline crosslinking agent, substances having more than one oxazoline group within one molecule can be used without particular restrictions.

[0224] Examples of aziridine-based crosslinking agents include trimethylolpropane tris[3-(1-aziridine)propionate] and trimethylolpropane tris[3-(1-(2-methyl)aziridine propionate)].

[0225] As a carbodiimide-based crosslinking agent, low-molecular-weight compounds or high-molecular-weight compounds having two or more carbodiimide groups can be used.

[0226] In several methods, peroxides can also be used as crosslinking agents. Examples of peroxides include di(2-ethylhexyl) peroxide dicarbonate, di(4-tert-butylcyclohexyl) peroxide dicarbonate, disec-butyl peroxide dicarbonate, tert-butyl peroxyneodecanate, tert-hexyl peroxynepentanoate, tert-butyl peroxynepentanoate, dilauroyl peroxide, dioctanoyl peroxide, 1,1,3,3-tetramethylbutyl peroxide, and benzoyl peroxide. Among these, di(4-tert-butylcyclohexyl) peroxide dicarbonate, dilauroyl peroxide, and benzoyl peroxide are examples of peroxides with particularly excellent crosslinking efficiency. It should be noted that when using peroxides as the polymerization initiator, the peroxides remaining from the polymerization reaction can also be used in the crosslinking reaction. In this case, the residual amount of peroxide is quantified, and if the proportion of peroxide does not meet the specified amount, peroxide can be added as needed to achieve the specified amount. The quantification of peroxides can be performed using the method described in Japanese Patent No. 4971517.

[0227] There is no particular limitation on the amount of crosslinking agent used (the total amount when using two or more crosslinking agents). From the viewpoint of achieving a balanced adhesive property such as adhesion and cohesion, it is appropriate for the amount of crosslinking agent to be about 5 parts by weight or less per 100 parts by weight of polymer (A), and it can be 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, or even less than 1 part by weight. In the combination of crosslinking agent and photoreactive monomer (B), from the viewpoint of easily and appropriately exerting the effect brought about by the combination, the amount of crosslinking agent per 100 parts by weight of polymer (A) can 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. There is no particular limitation on the lower limit of the amount of crosslinking agent, and it can be used in an amount more than 0 parts by weight per 100 parts by weight of polymer (A). In several ways, the amount of crosslinking agent relative to 100 parts by weight of polymer (A) may be, for example, 0.001 parts by weight or more, 0.01 parts by weight or more, or 0.03 parts by weight or more.

[0228] The technology disclosed herein is preferably implemented by using at least an isocyanate-based crosslinking agent as the crosslinking agent. It is also possible to use an isocyanate-based crosslinking agent in combination with other crosslinking agents. In the method of using an isocyanate-based crosslinking agent, the amount of isocyanate-based crosslinking agent relative to 100 parts by weight of polymer (A) can 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. Furthermore, the amount of isocyanate-based crosslinking agent relative to 100 parts by weight of polymer (A) can 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.

[0229] To make the crosslinking reaction proceed more efficiently, a crosslinking catalyst can also be used. Examples of crosslinking catalysts include tetrabutyl titanate, tetraisopropyl titanate, iron acetylacetone (NACEM® Iron (Ⅲ)), butyltin oxide, and dioctyltin laurate, among other metal-based crosslinking catalysts. Tin-based crosslinking catalysts, such as dioctyltin laurate, are preferred. There is no particular limitation on the amount of crosslinking catalyst used. The amount of crosslinking catalyst relative to 100 parts by weight of polymer (A) 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, etc. Furthermore, it can be set to about 1 part by weight or less, about 0.1 parts by weight or less, about 0.05 parts by weight or less, etc.

[0230] In the adhesive composition used to form the adhesive layer, a compound that undergoes keto-enol tautomerism may be included as a crosslinking delay agent, depending on the desired purpose. For example, in adhesive compositions containing isocyanate-based crosslinking agents or adhesive compositions that can be mixed with isocyanate-based crosslinking agents, a compound that undergoes keto-enol tautomerism is preferably used. This can extend the pot life of the adhesive composition.

[0231] Various β-dicarbonyl compounds can be used as compounds that undergo keto-enol tautomerism. Specific examples include β-diketones such as acetylacetone and 2,4-hexanedione; acetoacetate esters such as methyl acetoacetate and ethyl acetoacetate; propionyl acetate esters such as ethyl propionyl; isobutyryl acetate esters such as ethyl isobutyryl; and malonates such as methyl malonate and ethyl malonate. Suitable compounds among these include acetylacetone and acetoacetate esters. One type of keto-enol tautomerism compound can be used alone, or in combination of two or more.

[0232] The amount of the compound that will undergo keto-enol tautomerism relative to 100 parts by weight of polymer (A) may be, for example, more than 0.1 parts by weight and less than 20 parts by weight, more than 0.5 parts by weight and less than 15 parts by weight, more than 1 part by weight and less than 10 parts by weight, or more than 1 part by weight and less than 5 parts by weight.

[0233] (Silane coupling agent)

[0234] The adhesive layer of the adhesive sheet disclosed herein may contain a silane coupling agent as desired. The use of the silane coupling agent improves the peel strength of the adhesive sheet from the adhered object (e.g., a glass plate). The adhesive layer containing the silane coupling agent can be suitably formed using an adhesive composition containing the silane coupling agent. In the adhesive composition, from the viewpoint of inhibiting gelation, the silane coupling agent is preferably contained in a free form. Furthermore, in several ways, the silane coupling agent is preferably contained in a free form in the adhesive layer of the adhesive sheet disclosed herein. The silane coupling agent contained in the adhesive layer in this form can effectively contribute to improving peel strength. It should be noted that "free form" here means that the silane coupling agent is not chemically bonded to any other components contained in the adhesive composition or adhesive layer.

[0235] Examples of silane coupling agents include silicon compounds with epoxy structures such as 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropylmethyldimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane; 3-chloropropyltrimethoxysilane; silane coupling agents containing (meth)acrylic acid groups such as acetoacetyltrimethoxysilane, 3-acryloyloxypropyltrimethoxysilane, and 3-methacryloyloxypropyltriethoxysilane; and isocyanate-containing silane coupling agents such as 3-isocyanatepropyltriethoxysilane. In several embodiments, the aforementioned effects can be more preferably achieved by using a silane coupling agent having a trialkoxysilyl group. Examples of preferred silane coupling agents include 3-epoxypropoxypropyltrimethoxysilane and trimethoxysilane containing acetylacetyl groups.

[0236] The amount of silane coupling agent used can be set in a way that achieves the desired effect, and there is no particular limitation. In some cases, the amount of silane coupling agent relative to 100 parts by weight of polymer (A) can be, for example, 0.001 parts by weight or more. From the viewpoint of obtaining a higher effect, it can be 0.01 parts by weight or more, 0.05 parts by weight or more, or 0.1 parts by weight or more. Furthermore, from the viewpoint of inhibiting gelation of the adhesive composition, it is appropriate to set the amount of silane coupling agent relative to 100 parts by weight of polymer (A) to 3 parts by weight or less, or it can be 1 part by weight or less, or 0.5 parts by weight or less.

[0237] (Photopolymerization initiator)

[0238] The adhesive layer of the adhesive sheet disclosed herein may contain a photopolymerization initiator as needed for purposes such as improving or imparting photocurability. As the photopolymerization initiator, similar to the photopolymerization initiators exemplified as those used in the synthesis of polymer (A), ketal-based photopolymerization initiators, acetophenone-based photopolymerization initiators, benzoin ether-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, α-keto alcohol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzoyl photopolymerization initiators, thioxanone-based photopolymerization initiators, etc., may be used alone or in combination of two or more suitable initiators.

[0239] Specific examples of ketal-based photopolymerization initiators include 2,2-dimethoxy-1,2-diphenylethane-1-one, etc.

[0240] Specific examples of acetophenone-based photopolymerization initiators include 1-hydroxycyclohexylphenyl-one, 4-phenoxydichloroacetophenone, 4-tert-butyldichloroacetophenone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, methoxyacetophenone, etc.

[0241] Specific examples of benzoin ether-based photopolymerization initiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and other benzoin ethers, as well as substituted benzoin ethers such as methyl anisole.

[0242] Specific examples of acylphosphine oxide photopolymerization initiators include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide.

[0243] Specific examples of α-ketool-based photopolymerization initiators include 2-methyl-2-hydroxyphenylacetone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropane-1-one. Specific examples of aromatic sulfonyl chloride-based photopolymerization initiators include 2-naphthalenesulfonyl chloride. Specific examples of photoactive oxime-based photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(O-ethoxycarbonyl)-oxime. Specific examples of benzoin-based photopolymerization initiators include benzoin. Specific examples of benzoin-based photopolymerization initiators include benzoin.

[0244] Specific examples of benzophenone-based photopolymerization initiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinyl benzophenone, and α-hydroxycyclohexylphenyl ketone.

[0245] Specific examples of thioxanthone-based photopolymerization initiators include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone, etc.

[0246] The content of the photopolymerization initiator in the adhesive layer is not particularly limited and can be set in a way that appropriately achieves the desired effect. In several ways, the content of the photopolymerization initiator relative to 100 parts by weight of the polymer (A) contained in the adhesive layer can be, for example, about 0.005 parts by weight or more, 0.01 parts by weight or more is appropriate, preferably 0.05 parts by weight or more, 0.10 parts by weight or more, 0.15 parts by weight or more, or 0.20 parts by weight or more. Increasing the content of the photopolymerization initiator tends to improve the photocurability of the adhesive layer. Furthermore, the content of the photopolymerization initiator relative to 100 parts by weight of the polymer (A) is appropriate, preferably 7 parts by weight or less, 5 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, or 1 part by weight or less. From the viewpoint of improving the storage stability of the adhesive sheet (e.g., stability against photodegradation), it is advantageous to keep the content of the photopolymerization initiator moderate.

[0247] An adhesive layer containing a photopolymerization initiator is typically formed using an adhesive composition (e.g., a solvent-based adhesive composition) containing the photopolymerization initiator. An adhesive composition containing a photopolymerization initiator can be prepared, for example, by mixing other components used in the composition with the photopolymerization initiator. Furthermore, when preparing an adhesive composition using a polymer (A) synthesized (photopolymerized) in the presence of a photopolymerization initiator (e.g., an acrylic polymer (A)), the residue (unreacted material) of the photopolymerization initiator used in the synthesis of the polymer (A) can be used as part or all of the photopolymerization initiator contained in the adhesive layer. The same applies when using an acrylic oligomer synthesized in the presence of a photopolymerization initiator as needed. From the viewpoint of ease of manufacturing management, the adhesive layer disclosed herein is preferably formed using an adhesive composition prepared by adding the aforementioned amount of photopolymerization initiator to other constituent components.

[0248] The adhesive layer or adhesive composition of the adhesive sheet disclosed herein may, as needed, include tackifying resins (e.g., rosin-based, petroleum-based, terpene-based, phenolic, ketone-based, etc.), viscosity modifiers (e.g., thickeners), leveling agents, plasticizers, fillers, colorants such as pigments and dyes, stabilizers, preservatives, anti-aging agents, and various other additives commonly used in the field of adhesives as optional components. Such additives can be obtained using conventional methods from existing known substances and are not particularly characteristic of this invention; therefore, detailed descriptions are omitted.

[0249] It should be noted that the technology disclosed herein can achieve good adhesive strength without the use of the aforementioned tackifying resin. Therefore, in several embodiments, the content of the aforementioned tackifying resin in the adhesive layer or adhesive composition may, for example, be less than 10 parts by weight, and further less than 5 parts by weight, relative to 100 parts by weight of polymer (A). The content of the aforementioned tackifying resin may be less than 1 part by weight (e.g., less than 0.5 parts by weight) or less than 0.1 parts by weight (more than 0 parts by weight but less than 0.1 parts by weight). The aforementioned adhesive layer or adhesive composition may not contain the tackifying resin.

[0250] From a transparency perspective, the amount of components other than the polymer (A) and the aforementioned photoreactive monomer (B) used as required in the adhesive layer (or the adhesive composition used to form the adhesive layer) is preferably limited. In the art disclosed herein, it is suitable for the amount of components other than the polymer (A) and the photoreactive monomer (B) in the adhesive layer to be about 30% by weight or less, about 15% by weight or less, and preferably about 12% by weight or less (e.g., about 10% by weight or less). In several types of adhesive sheets, the amount of components other than the polymer (A) and the photoreactive monomer (B) in the 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).

[0251] <Form of Adhesive Composition>

[0252] The adhesive layer can be formed using an adhesive composition containing monomer components with the aforementioned composition in the form of a polymer, an unpolymer (i.e., a form in which polymeric functional groups are unreacted), or a mixture thereof. The adhesive composition can take various forms, including: a composition containing the adhesive (adhesive component) in an organic solvent (solvent-based adhesive composition); a composition in which the adhesive is dispersed in an aqueous solvent (water-dispersible adhesive composition); a composition prepared by curing using active energy rays such as ultraviolet light or radiation to form an adhesive (active energy ray curable adhesive composition); and a hot-melt adhesive composition formed by coating in a molten state and cooling to near room temperature. From the viewpoints of ease of preparation of the adhesive composition and ease of forming the adhesive layer, solvent-based adhesive compositions are preferred in several ways. Solvent-based adhesive compositions are preferably prepared using polymer (A), which is a polymer obtained by solution polymerization of monomer components.

[0253] It should be noted that, in this specification, "active energy rays" refers to energy rays that possess the energy to initiate chemical reactions such as polymerization, cross-linking, and decomposition of initiators. Examples of active energy rays mentioned here include light such as ultraviolet rays, visible light, and infrared rays, as well as radiation such as alpha rays, beta rays, gamma rays, electron beams, neutron beams, and X-rays.

[0254] The aforementioned adhesive composition typically comprises at least a portion (either a portion of the monomer components or a portion of the monomer type) in polymer form. The polymerization method used to form the polymer is not particularly limited, and various known polymerization methods can be appropriately employed. For example, thermal polymerization such as solution polymerization, emulsion polymerization, and bulk polymerization (typically carried out in the presence of a thermal polymerization initiator) can be appropriately employed; photopolymerization by irradiation with ultraviolet light (typically carried out in the presence of a photopolymerization initiator); and radiation polymerization by irradiation with beta rays, gamma rays, etc. In these polymerization methods, the polymerization mode is not particularly limited, and existing known monomer supply methods, polymerization conditions (temperature, time, pressure, light irradiation, radiation irradiation, etc.), and materials used other than monomers (polymerization initiators, surfactants, etc.) can be appropriately selected.

[0255] During polymerization, known or conventional photopolymerization initiators and thermal polymerization initiators may be used, depending on the polymerization method and polymerization mode. Examples of photopolymerization initiators and thermal polymerization initiators have been described above, and therefore, repeated descriptions are omitted. One such polymerization initiator may be used alone, or two or more may be used in combination as appropriate.

[0256] (Adhesive compositions comprising monomeric components and unpolymerized components)

[0257] Several types of adhesive compositions comprise: a polymerization product of a monomer mixture containing at least a portion of the monomeric components (starter monomers) of the composition. Typically, a portion of the monomeric components is contained in polymer form, while the remainder is contained in unpolymerized (unreacted) form. The polymerization product of the monomer mixture can be prepared by polymerizing at least a portion of the monomer mixture.

[0258] The polymerization product is preferably a partial polymer of the monomer mixture described above. This partial polymer is a mixture of polymer derived from the monomer mixture and unreacted monomers, and is typically in the form of a slurry (a viscous liquid). Hereinafter, this partial polymer is sometimes referred to as a "monomer slurry," "polymer slurry," or simply "slurry."

[0259] There are no particular limitations on the polymerization method used to obtain the above-described polymerization products; various polymerization methods described above can be appropriately selected. From the viewpoint of efficiency and simplicity, photopolymerization is preferred. When using photopolymerization, the polymerization conversion rate of the monomer mixture can be easily controlled by using polymerization conditions such as the amount of light irradiation (light intensity).

[0260] The polymerization conversion rate (monomer conversion rate) of the monomer mixture in the aforementioned polymer is not particularly limited. For example, the polymerization conversion rate can be set to about 70% by weight or less, preferably about 60% by weight or less. From the viewpoint of ease of preparation and coatability of the adhesive composition containing the aforementioned polymer, a polymerization conversion rate of about 50% by weight or less is suitable, and preferably about 40% by weight or less (e.g., about 35% by weight or less). There is no particular limitation on the lower limit of the polymerization conversion rate; typically, about 1% by weight or more, and about 5% by weight or more, are suitable.

[0261] An adhesive composition comprising a partial polymer of the monomer mixture described above can be readily obtained, for example, by partially polymerizing the monomer mixture containing all the raw material monomers using a suitable polymerization method (e.g., photopolymerization). Other components (e.g., photopolymerization initiators, multifunctional monomers, crosslinking agents, acrylic oligomers described later) may be compounded into the adhesive composition comprising the partial polymer as needed. The method of compounding such other components is not particularly limited; for example, they may be pre-included in the monomer mixture or added to the partial polymer.

[0262] Alternatively, the adhesive composition disclosed herein may also be a form in which a complete polymer of a monomer mixture comprising a portion of the monomers (raw monomers) is dissolved in the remaining monomers or a portion thereof. Such adhesive compositions also include examples of adhesive compositions comprising both monomeric components and unpolymerized polymers. It should be noted that, in this specification, "complete polymer" means a polymerization conversion exceeding 95% by weight.

[0263] Photopolymerization is a preferred curing method (polymerization method) for adhesives formed from polymers and unpolymerized adhesive compositions containing monomeric components. Photopolymerization is particularly suitable as a curing method for adhesive compositions containing polymerization products prepared by photopolymerization. Since the polymerization products obtained by photopolymerization already contain a photopolymerization initiator, photopolymerization can be performed even without adding a new photopolymerization initiator when the adhesive composition containing this polymerization product is further cured to form an adhesive. Alternatively, an adhesive composition in which a photopolymerization initiator is added to the polymerization product prepared by photopolymerization as needed can also be used. The added photopolymerization initiator can be the same as or different from the photopolymerization initiator used in the preparation of the polymerization product. Adhesive compositions prepared by methods other than photopolymerization can be photocurable by adding a photopolymerization initiator. Photocurable adhesive compositions have the advantage of being easily formed even in relatively thick adhesive layers. In several preferred embodiments, photopolymerization when forming an adhesive from an adhesive composition can be carried out by ultraviolet irradiation. Known high-pressure mercury lamps, low-pressure mercury lamps, metal halide lamps, etc., can be used for ultraviolet irradiation.

[0264] (An adhesive composition containing monomer components in the form of a complete polymer)

[0265] Other types of adhesive compositions contain monomeric components of the adhesive composition in the form of a complete polymer. Such adhesive compositions may be, for example, solvent-based adhesive compositions in which the complete polymer of an acrylic polymer as a monomeric component is contained in an organic solvent, or water-dispersible adhesive compositions in which the aforementioned acrylic polymer is dispersed in an aqueous solvent.

[0266] (Thickness of the adhesive layer)

[0267] The thickness of the adhesive layer is not particularly limited. The thickness of the adhesive layer can be, for example, about 1 μm to 500 μm, or, for example, about 3 μm to 500 μm. In several embodiments, a thickness of 5 μm or more is suitable, for example, 10 μm or more, preferably 20 μm or more, more preferably 25 μm or more, and may also exceed 25 μm. When the thickness of the adhesive layer increases, there is a tendency for the stress dispersion ability in the adhesive layer to increase. This can advantageously contribute to the reduction of optical distortion. Furthermore, a thicker adhesive layer tends to have excellent height difference following properties and easily absorbs deformation caused by foreign objects, etc. There is also a tendency for improved impact resistance. The technology disclosed herein can preferably be implemented with an adhesive layer thickness of, for example, 30 μm or more. The aforementioned adhesive layer thickness can be 35 μm or more, or 40 μm or more, or 45 μm or more, or 50 μm or more, or 75 μm or more, or 90 μm or more. On the other hand, as the thickness of the adhesive layer increases, the light path passing through it also becomes longer, making optical distortion easier to observe. Therefore, in several ways, it is appropriate for the adhesive layer thickness to be, for example, 200 μm or less; it can be 150 μm or less; it can also be 120 μm or less; preferably 100 μm or less; more preferably 70 μm or less; even more preferably 50 μm or less; and it can also be 35 μm or less. An adhesive layer with this thickness will better suppress deformation of the adhesive layer. Using the technology disclosed herein, by having an adhesive layer with a thickness of, for example, 70 μm or less, high deformation resistance and high impact resistance can be formed.

[0268] It should be noted that the thickness of the adhesive layer can be measured using a 1 / 1000mm dial indicator on a planar measuring instrument. For example, in the case of a structure consisting of a release film / adhesive layer / release film, the total thickness can be measured using a 1 / 1000mm dial indicator on a planar measuring instrument, and the thickness of the release film can be subtracted to calculate the thickness.

[0269] (Peak temperature of tanδ)

[0270] The adhesive constituting the adhesive layer disclosed herein preferably has a peak temperature of the loss tangent tanδ in the range of -50°C to 0°C. Good impact resistance is readily obtained when using an adhesive with a tanδ peak in the low-temperature region. The peak temperature of the adhesive's loss tangent tanδ can be determined by the following method: A dynamic viscoelasticity measurement is performed under the same conditions as the measurement of the storage modulus at 25°C described below, and the storage modulus G' and loss modulus G'' are measured. Then, the loss tangent tanδ is calculated using the following formula: tanδ = G'' / G', and its temperature dependence is plotted to determine the temperature corresponding to its peak (the temperature at which the tanδ curve reaches its maximum).

[0271] (Storage modulus at 25℃)

[0272] The storage modulus of the adhesive layer at 25°C (storage modulus at 25°C) is appropriately set according to the intended use and application method, and is not limited to a specific range. From the viewpoint of adhesive properties such as deformation resistance and heat resistance, the aforementioned storage modulus at 25°C is set to approximately 4 × 10⁻⁶. 4 Pa or higher is appropriate, preferably about 6 × 10 Pa. 4 Pa or higher, more preferably about 8 × 10 Pa 4 Pa or higher, approximately 1.0 × 10 5 Pa or higher, or approximately 1.2 × 10⁻⁶. 5 Pa or above, or approximately 1.5 × 10 5 Pa or higher, or approximately 1.8 × 10⁻⁶. 5 Pa or higher. The aforementioned adhesive layer with a high storage modulus at 25°C tends to exhibit excellent resistance to compressive deformation. However, the aforementioned storage modulus at 25°C is, for example, less than 1 × 10⁻⁶. 7 Pa, approximately 1 × 10 6 Pa or less is appropriate. From the viewpoint of suitably exhibiting adhesive properties such as tackiness, the above-mentioned storage modulus at 25°C is preferably about 5.0 × 10⁻⁶. 5 Pa or less, more preferably about 3.0 × 10 Pa 5 Pa or less, more preferably about 2.0 × 10 Pa 5 Below Pa, it can be approximately 1.4 × 10⁻⁶. 5 Below Pa, or approximately 1.0 × 10⁻⁶. 5 Below Pa. The storage modulus of the adhesive sheet (typically a substrate-free adhesive sheet) at 25°C is also preferably set within the range of the examples described 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 determined by the method described below. The same applies to the examples described later.

[0273] [Storage Modulus at 25℃]

[0274] Multiple adhesive sheets or adhesive layers to be tested are overlapped to create an adhesive layer with a thickness of approximately 2 mm. This adhesive layer is then punched into a disc shape with a diameter of 7.9 mm. The resulting sample is clamped and fixed with parallel plates, and dynamic viscoelasticity is measured using a viscoelastic testing machine (e.g., TA Instruments, Inc., ARES, or equivalent) under the following conditions to determine the storage modulus G´(25℃) [Pa] at 25℃.

[0275] Measurement mode: Shear mode

[0276] Temperature range: -70℃ to 150℃

[0277] Heating rate: 5℃ / min

[0278] Measurement frequency: 1Hz

[0279] (Gel ratio)

[0280] The gelation rate of the adhesive layer is appropriately set according to the intended use and application method, and is not limited to a specific range. For example, a gelation rate of about 99% by weight or less, or about 97% by weight or less, is suitable. From the viewpoint of height difference tracking, among several preferred embodiments, the gelation rate is about 95% by weight or less, more preferably about 92% by weight or less, and can be about 88% by weight or less, or about 75% by weight or less, or about 65% by weight or less. An adhesive layer with the above gelation rate, for example, when a mark or other printing is formed on the surface of the adhered object, can well follow the unevenness of the printing without impairing visual recognizability. Furthermore, from the viewpoint of exhibiting good adhesive and viscoelastic properties, a gelation rate of the adhesive layer of, for example, about 10% by weight or more, or about 20% by weight or more, is suitable. From the viewpoint of deformation resistance, the gelation rate is preferably about 30% by weight or more, more preferably about 40% by weight, and can be about 50% by weight or more, or about 65% by weight or more, or about 75% by weight or more. The gel ratio of the adhesive sheet (typically a substrate-free adhesive sheet) is preferably set within the range described above. The gel ratio can be adjusted by the molecular weight, molecular structure, concentration, and degree of crosslinking of the base polymer. The gel ratio is determined by the method described below. The same applies to the examples described later.

[0281] [Gel ratio]

[0282] A specified amount of adhesive sample (weight Wg1) was wrapped in a porous polytetrafluoroethylene membrane (weight Wg2) with an average pore size of 0.2 μm and tied with cotton thread (weight Wg3). The porous polytetrafluoroethylene (PTFE) membrane used was the product "Nitoflon (registered trademark) NTF1122" (average pore size 0.2 μm, porosity 75%, thickness 85 μm) or an equivalent product available from Nitto Denko Corporation.

[0283] The package was immersed in a sufficient amount of ethyl acetate and kept at room temperature (typically 23°C) for 7 days, allowing only the sol component in the adhesive layer to dissolve to the outside of the membrane. The package was then removed, the ethyl acetate adhering to the outer surface was wiped off, and the package was dried at 130°C for 2 hours. The weight of the package (Wg4) was measured. The gelation rate of the adhesive layer was calculated by substituting the values ​​into the following formula.

[0284] Gelation rate (%) = [(Wg4 - Wg2 - Wg3) / Wg1] × 100

[0285] It should be noted that the adhesive sheet disclosed herein includes adhesive sheets in the form of adhesive layers that are light-cured after being adhered to the substrate. Therefore, at least for light-curable adhesive sheets (such as the adhesive sheet of Example 4 having adhesive C described later), an illuminance of 300 mW / cm² is used. 2 Cumulative light intensity 3000 mJ / cm 2 Samples subjected to ultraviolet irradiation and curing at 50°C for 48 hours were tested for tanδ peak temperature, storage modulus at 25°C, gelation rate, total transmittance, haze value, maximum height Rz of the adhesive surface, arithmetic mean roughness Ra, adhesive force, elastic modulus based on tensile test, and impact resistance. For the above ultraviolet irradiation treatment, when the release film is transparent, it is preferable to perform the treatment while the adhesive sheet (representatively the adhesive layer) is sandwiched between the transparent release film.

[0286] <Supporting substrate>

[0287] Several types of adhesive sheets can be in the form of adhesive sheets with a supporting substrate. The material of the supporting substrate is not particularly limited and can be selected appropriately based on the intended use and application method of the adhesive sheet. Non-limiting examples of usable supporting substrates include polyolefin films with polyolefins such as polypropylene and ethylene-propylene copolymer as the main component; polyester films with polyesters such as polyethylene terephthalate and polybutylene terephthalate as the main component; polyvinyl chloride films with polyvinyl chloride as the main component; foamed sheets formed from foams such as polyurethane foam, polyethylene foam, and polychloroprene foam; fabrics and nonwovens formed from various fibrous materials (such as natural fibers like hemp and cotton, synthetic fibers like polyester and vinylon, and semi-synthetic fibers like cellulose acetate) alone or through blending; paper types such as Japanese paper, high-quality paper, kraft paper, and crepe paper; and metal foils such as aluminum foil and copper foil. Supporting substrates composed of these composite materials can also be used. Examples of supporting substrates for such composite structures include supporting substrates consisting of metal layers (e.g., metal foil, continuous or discontinuous metal sputtered layers, metal vapor-deposited layers, metal plating layers, etc.), metal oxide layers laminated with the aforementioned resin films, and resin sheets reinforced with inorganic fibers such as glass cloth. These supporting substrates can correspond to optical components (e.g., optical films) described later, or they can be transparent components formed from transparent materials (e.g., transparent resin materials, glass, etc.).

[0288] As the supporting substrate for the adhesive sheet disclosed herein, various films (hereinafter also referred to as supporting films) can preferably be used. The supporting film can be a porous film such as a foamed film or a non-woven fabric sheet, or it can be a non-porous film, or a film with a structure consisting of layers of porous and non-porous materials. In several embodiments, the supporting film preferably uses a supporting film comprising a resin film that can independently maintain its shape (self-supporting or independent) as the base film. Here, "resin film" refers to a non-porous structure, typically a resin film that is substantially free of air bubbles (non-porous). Therefore, the resin film is a concept distinct from foamed films and non-woven fabrics. The resin film can be a single-layer structure or a multi-layer structure with two or more layers (e.g., a three-layer structure).

[0289] Resin materials constituting the resin film can be, for example, polyester, polyolefins, polycyclic olefins derived from monomers having aliphatic ring structures such as norbornene, nylon 6, nylon 66, polyamides (PA) such as partially aromatic polyamides, polyimides (PI), polyamide-imides (PAI), polyetheretherketones (PEEK), polyethersulfones (PES), polyphenylene sulfide (PPS), polycarbonate (PC), polyurethane (PU), ethylene-vinyl acetate copolymers (EVA), polystyrene, polyvinyl chloride, polyvinylidene chloride, polytetrafluoroethylene (PTFE) and other fluororesins, acrylic resins such as polymethyl methacrylate, cellulose polymers such as cellulose diacetate and cellulose triacetate, vinyl butyral polymers, acrylate polymers, polyoxymethylene polymers, epoxy polymers, and other resins. The above-mentioned resin film can be formed using a resin material containing only one such resin, or it can be formed using a blend of two or more resin materials. The above-mentioned resin film can be unstretched or stretched (e.g., uniaxially stretched or biaxially stretched).

[0290] Preferred examples of resin materials constituting resin films include polyester resins, PPS resins, and polyolefin resins. Here, polyester resin refers to a resin containing polyester in a proportion exceeding 50% by weight. Similarly, PPS resin refers to a resin containing PPS in a proportion exceeding 50% by weight, and polyolefin resin refers to a resin containing polyolefin in a proportion exceeding 50% by weight.

[0291] A representative example of polyester resins is one that uses polyester, obtained by polycondensation of dicarboxylic acid and diol, as its main component. Specific examples of polyester resins include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polybutylene naphthalate.

[0292] As a polyolefin resin, a single polyolefin or a combination of two or more polyolefins can be used. This polyolefin can be, for example, a homopolymer of α-olefin, a copolymer of two or more α-olefins, or a copolymer of one or more α-olefins with other vinyl monomers. Specific examples include polyethylene (PE), polypropylene (PP), poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene 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) and high-density (HD) polyolefins can be used. Examples of polyolefin resin films include unstretched polypropylene (CPP) film, biaxially stretched 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 from a blend of two or more types of polyethylene (PE), and PP / PE blend film made from a blend of polypropylene (PP) and polyethylene (PE).

[0293] Specific examples of resin films that are preferably used as support substrates include PET film, PEN film, PPS film, PEEK film, CPP film, and OPP film. Examples preferred from a strength perspective include PET film, PEN film, PPS film, and PEEK film. Examples preferred from the viewpoints of ease of acquisition, dimensional stability, and optical properties include PET film.

[0294] Resin films can be formulated with known additives such as light stabilizers, antioxidants, antistatic agents, colorants (dyes, pigments, etc.), fillers, slip agents, and antiblocking agents as needed. The amount of additives used is not particularly limited and can be appropriately determined based on the intended use of the adhesive film.

[0295] There are no particular limitations on the manufacturing method of resin films. For example, existing and well-known common resin film forming methods such as extrusion molding, blow molding, T-die casting, and calendering roll forming can be used.

[0296] The aforementioned support substrate can be a support film substantially composed of such a resin film. Alternatively, the aforementioned support substrate can also be a support film that includes auxiliary layers in addition to the aforementioned resin film. The auxiliary layers can be disposed on the adhesive layer side of the resin film, on the side opposite to the adhesive layer, or on both sides of the resin film. Examples of the aforementioned auxiliary layers include optical property adjustment layers (e.g., coloring layers, anti-reflective layers), decorative layers that impart a desired appearance to the support substrate or adhesive sheet (e.g., printed layers, laminated layers, continuous or discontinuous metal layers, continuous or discontinuous metal oxide layers, etc.), conductive layers, antistatic layers, primer layers, release layers, etc.

[0297] In several embodiments, the support substrate is preferably a transparent plastic film. In this embodiment, the total light transmittance of the support substrate is, for example, about 50% or more, or, for example, about 70% or more. From the viewpoint of visual recognizability of the adhered object through the adhesive sheet, in several preferred embodiments, the total light transmittance of the support substrate is about 85% or more, more preferably about 90% or more. The upper limit of the aforementioned total light transmittance can, in practical terms, be about 95% or less, or about 94% or less (e.g., 93% or less).

[0298] It should be noted that the total light transmittance of the supporting substrate can be measured using a haze meter. The haze meter can be the "HM-150N" or an equivalent manufactured by the Murakami Color Technology Research Institute.

[0299] The thickness of the support substrate is not particularly limited and can be selected according to the intended use and application method of the adhesive sheet. For example, the thickness of the support substrate can be 1000 μm or less. From the viewpoint of processability (e.g., ease of winding), 500 μm or less is appropriate, preferably 300 μm or less, and can 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 decreases, the flexibility of the adhesive sheet and its ability to follow the surface shape of the adhered object tend to improve. Furthermore, from the viewpoint of processability and workability, the thickness of the support substrate can be, for example, 2 μm or more, or more than 5 μm or more than 10 μm. In some cases, the thickness of the support substrate can be, for example, 20 μm or more, 35 μm or more, or 55 μm or more.

[0300] For the side of the support substrate that contacts the adhesive layer, existing known surface treatments such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, application of a primer, and antistatic treatment can be applied as needed. This surface treatment can be used to improve the adhesion between the support substrate and the adhesive layer, in other words, the anchoring effect of the adhesive layer on the support substrate. The composition of the primer is not particularly limited and can be appropriately selected from known compositions. The thickness of the primer layer is not particularly limited, but approximately 0.01 μm to 1 μm is appropriate, and preferably approximately 0.1 μm to 1 μm.

[0301] <Method for manufacturing adhesive sheets with release film>

[0302] The method for manufacturing the adhesive sheet with a release film disclosed herein is not particularly limited. For example, an adhesive composition can be applied to the release surface of the release film, and then dried (e.g., by heat drying) or cured to form an adhesive layer on the release surface. Different release films can then be laminated on the surface of the adhesive layer opposite to the release surface to obtain an adhesive sheet with a release film. Alternatively, an adhesive composition sandwiched between two release films can be dried or cured to form an adhesive layer, thereby forming an adhesive sheet with a release film. For adhesive sheets having a support substrate, for example, a method can be used whereby an adhesive composition is applied to the support substrate and dried or cured to form an adhesive layer (direct method). Alternatively, a method can be used where an adhesive composition is applied to a release surface (release surface) and dried to form an adhesive layer on that surface, and then the adhesive layer is transferred to the support substrate (transfer method).

[0303] The curing process may include crosslinking (e.g., crosslinking based on the reaction of the aforementioned crosslinking agent), cooling, etc. When two or more curing processes are performed, they can be carried out simultaneously or sequentially. Various methods known in the art can be used as the coating method for the adhesive composition. Specifically, examples include, for instance, roller coating, licker coating, gravure coating, reverse coating, roller brush coating, spray coating, dip roller coating, bar coating, doctor blade coating, air knife coating, curtain coating, lip coating, and extrusion coating based on a die-casting machine.

[0304] The adhesive sheet with a release film disclosed herein can be suitably manufactured by a method comprising drying or curing a liquid film of an adhesive composition on the release surface of the release film to form an adhesive layer. Using this method, the adhesive composition (liquid film) in a fluid state is dried or cured in contact with the release surface, thereby enabling precise control over the smoothness of the adhesive layer surface formed in contact with the release surface. The release surface is characterized by a maximum height (Rz) limited to a specified value; by using a release film having such a release surface, a highly smooth adhesive surface can be stably (reproducibly) manufactured.

[0305] The adhesive sheet with a release film disclosed herein can preferably be manufactured by a method comprising: curing a 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 distributing 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 that involves coating a liquid adhesive composition onto the release surface of one release film, and then covering the liquid film of the adhesive composition with another release film. Other methods include supplying the first release film and the second release film to a pair of rollers with their release surfaces facing each other, and supplying a liquid adhesive composition between their release surfaces. It should be noted that the coating of the adhesive composition is preferably performed at 80°C or below, more preferably at 60°C or below (e.g., 40°C or below). This suppresses the roughness of the adhesive layer caused by the difference in the coefficients of thermal expansion between the first release film, the second release film, and the adhesive layer, resulting in a smoother adhesive surface.

[0306] The total thickness of the adhesive sheet with release film disclosed herein is not particularly limited, and can be, for example, approximately 30 μm to 1500 μm. Here, the total thickness of the adhesive sheet with release film refers to the combined thickness of the adhesive sheet with release film, which consists of at least one release film (including a first release film and a second release film) and the adhesive sheet. In several embodiments, the total thickness of the adhesive sheet with release film can be, for example, 60 μm or more, 80 μm or more, 105 μm or more, 125 μm or more, or 140 μm or more. The total thickness of the adhesive sheet with release film can be, for example, 1000 μm or less, 500 μm or less, or 300 μm or less.

[0307] <Wound Body>

[0308] According to this specification, a wound body (adhesive sheet roll with release film) comprising the adhesive sheet with release film disclosed herein in a wound form is provided. Such a wound body is typically composed of a core (wound core) and an adhesive sheet with release film wound around the core. The shape of the core is not particularly limited, and can be, for example, a solid cylindrical shape, a hollow cylindrical shape (i.e., a cylindrical shape), a hollow or solid polygonal prism shape, etc. From the viewpoint of improving the processability of the wound body, a hollow cylindrical or hollow polygonal prism-shaped core is preferred. A cylindrical core is particularly preferred.

[0309] <Paste to the object>

[0310] The method of attaching the adhesive sheet disclosed herein to the substrate is not particularly limited. Known or conventional crimping methods can be used depending on the intended use and method of application. In several preferred embodiments, the adhesive sheet can be used by a method including light-curing the adhesive layer after it has been attached to the substrate. By attaching the adhesive sheet to the substrate, a substrate with the adhesive sheet laminated is formed. By light-curing the adhesive layer of the adhesive sheet, a laminate containing the adhesive sheet with the cured adhesive layer and the substrate is obtained. Therefore, according to this specification, a method for attaching an adhesive sheet is provided, which sequentially includes: attaching any adhesive sheet disclosed herein to the substrate, and irradiating the adhesive sheet with ultraviolet light to light-cur the adhesive layer.

[0311] <Uses>

[0312] The adhesive sheet disclosed herein can be used for fixing, joining, molding, decorating, protecting, and supporting components of various products. The material of at least the surface of the aforementioned components can be, for example, glass such as alkali glass or alkali-free glass; metal materials such as stainless steel (SUS) or aluminum; resin materials such as acrylic resin, ABS resin, polycarbonate resin, polyimide resin, polyester resin such as PET, and polystyrene resin. These components can be, for example, components constituting various mobile devices (portable devices), automobiles, and home appliances. Furthermore, the surface on which the adhesive sheet is adhered can be a coated surface based on acrylic, polyester, alkyd, melamine, urethane, acid-epoxy cross-linked, or composite systems (e.g., acrylic-melamine, alkyd-melamine), or a plated surface of galvanized steel sheet. Additionally, the aforementioned components can be, for example, a resin film or an object having a continuous or discontinuous inorganic layer (which can be a metal layer, metal oxide layer, etc.) on the resin film.

[0313] As an example of preferred applications, optical applications can be cited. More specifically, for example, the adhesive sheet disclosed herein can be preferably used for optical applications such as bonding optical components (optical component bonding) and manufacturing products using the aforementioned optical components (optical products).

[0314] The aforementioned optical components refer to components possessing optical properties (e.g., polarization, refractivity, diffraction, optical rotation, etc.). There is no particular limitation on the term "optical component" as long as it possesses optical properties. Examples include components constituting display devices (image display devices), input devices, and other equipment (optical devices), or components used in these devices. Examples include polarizing plates, wavelength plates, phase retardation plates, optical compensation films, brightness enhancement films, light guide plates, reflective films, anti-reflective films, hard-coated (HC) films, impact-absorbing films, anti-fouling films, photochromic films, dimming films, transparent conductive films (ITO films), and components in which these are stacked (sometimes collectively referred to as "functional films"). It should be noted that the terms "plate" and "film" include plate-like, film-like, and sheet-like forms, respectively. For example, "polarizing film" includes "polarizing plate" and "polarizing sheet," etc.

[0315] Examples of display devices include liquid crystal displays, organic EL (electroluminescent) displays, PDP (plasma display panels), and electronic paper. Additionally, examples of input devices include touch panels.

[0316] The optical components mentioned above are not particularly limited, and for example, components made of glass, acrylic resin, polycarbonate, transparent polyimide, PET, etc. (e.g., sheet-like, film-like, plate-like components) can be listed.

[0317] There are no particular limitations on the method of using the adhesive sheet disclosed herein to bond optical components. For example, it can be (1) bonding optical components to each other using the adhesive sheet disclosed herein, (2) bonding optical components to components other than optical components using the adhesive sheet disclosed herein, or (3) bonding the adhesive sheet disclosed herein to an optical component or a component other than an optical component, where the adhesive sheet disclosed herein is in the form of containing an optical component. It should be noted that in the above-mentioned (3) method, the adhesive sheet in the form of containing an optical component can be, for example, an adhesive sheet whose supporting substrate is an optical component (e.g., an optical film). Such an adhesive sheet in the form of containing an optical component as a supporting substrate can also be understood as an adhesive optical component (e.g., an adhesive optical film). In addition, the adhesive sheet disclosed herein is an adhesive sheet of the type having a supporting substrate. When the above-mentioned functional film is used as the above-mentioned supporting substrate, the adhesive sheet disclosed herein can also be understood as an "adhesive functional film" having an adhesive layer disclosed herein on at least one side of the functional film.

[0318] The adhesive sheet disclosed herein is preferably used for attaching decorative films. Here, a decorative film refers to a film having an appearance design (including color, tone, pattern, and even textual information such as logos on its surface (decorative surface), also called an appearance design film or decorative film. The aforementioned decorative film includes components that serve both decorative and protective functions while maintaining the visual recognizability of image display devices and input devices. Examples of decorative films include, for instance, films having a decorative layer (printed layer, laminated layer, colored layer, gloss layer, continuous or discontinuous inorganic layer (metal layer, metal oxide layer, etc.) that imparts a desired appearance. Such decorative films can have an appearance design on their surface and provide good shielding properties.

[0319] The aforementioned decorative film may have a decorative layer. Examples of such decorative layers include printed layers, laminated layers, colored layers, gloss layers, and continuous or discontinuous inorganic layers that impart a desired appearance. Examples of continuous or discontinuous inorganic layers include continuous or discontinuous metal layers, continuous or discontinuous metal oxide layers, laminates of continuous or discontinuous metal layers and metal oxide layers, and continuous or discontinuous metal / metal oxide composite layers. Examples of such metals include aluminum, zinc, lead, copper, silver, and their alloys. Examples of such metal oxides include chromium oxide, indium oxide, zinc oxide, and titanium oxide. Metal layers and metal oxide layers can be formed by vapor deposition, sputtering, etc. As a representative example of a decorative film, a metallic-toned film can be described. A metallic-toned decorative film may possess electromagnetic wave transmittance in addition to a metallic luster. Examples of such decorative films include electromagnetic wave-transmitting metallic luster components described in Japanese Patent Application Publication No. 2018-69462, Japanese Patent Application Publication No. 2019-123238, and Japanese Patent Application Publication No. 2019-188805.

[0320] Furthermore, the decorative film specifically includes a substrate layer, and may have both a substrate layer and a decorative layer, with the decorative layer covering at least a portion of at least one surface of the substrate layer. As the substrate layer, various resin films, such as the aforementioned plastic film, can be used. Preferably, a resin film formed from polyester resins such as PET, polyolefin resins, polycarbonate resins, or (meth)acrylic resins is preferred. The thickness of the substrate layer is not particularly limited, but is, for example, approximately 5 to 250 μm. The decorative layer may be disposed on the adhesive side of the substrate layer, on the side opposite to the adhesive side, or on both sides of the substrate layer.

[0321] In decorative films containing decorative layers, the thickness of the decorative layer is preferably in the range of about 1 to 1000 nm, for example, about 1 to 300 nm or about 1 to 200 nm. Furthermore, a sheet resistance of 100 Ω / □ or higher is suitable, for example, 250 Ω / □ or higher, or 1000 Ω / □ or higher. Decorative films having such decorative layers can become radio-transparent films, and therefore are preferably used, for example, in various applications requiring radio-transparent properties, such as portable electronic devices. The upper limit of the sheet resistance of the decorative layer is not particularly limited, for example, it can be 1 × 10⁻⁶. 16 Below Ω / □. It should be noted that the above-mentioned sheet resistance can be measured according to the overcurrent test method described in JIS Z 2316.

[0322] The surface of the decorative film can be a flat plane or it can have printed markings or other textures caused by engraving. The adhesive sheet disclosed herein can be an adhesive sheet with excellent height difference following properties, thus enabling good adhesion to decorative film surfaces with the aforementioned textures.

[0323] Furthermore, the adhesive sheet disclosed herein is preferred for applications involving bonding transparent components or fixing two components, at least one of which is transparent, due to its excellent visual visibility of the adhered object based on its high surface smoothness. Examples of such component fixing applications include one component being transparent and the other 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 components having image display surfaces, decorative surfaces, or colored surfaces to transparent components. Examples of image display surfaces include liquid crystal display surfaces, organic EL display surfaces, PDPs, and electronic paper. Examples of decorative surfaces include the decorative surfaces of decorative films. Examples of colored surfaces include the surfaces of light-shielding films and opaque films. Transparent components can be made from transparent materials including resins such as glass, acrylic resins, polycarbonate, and PET. In this configuration, by using an adhesive sheet with a total light transmittance and haze value of at least a specified value, the image display surface, decorative surface, or colored surface of the adhered component can be clearly visually identified through the adhesive sheet and the transparent component.

[0324] The aforementioned transparent component can be a flat plate, or it can have printing, engraving, or other raised or recessed features on the adhesive surface. Alternatively, the transparent component can be a single, three-dimensional structure. The adhesive sheet disclosed herein can be an adhesive sheet with excellent height difference tracking, thus ensuring good adhesion even to the surface of the aforementioned raised or recessed transparent component. Furthermore, the three-dimensional transparent component can have a straight or curved section in its thickness direction. The aforementioned transparent component can have an adhesive surface that is bent or curved in any direction, or it can have a shape that is bent or curved in both directions: one direction and a direction intersecting (e.g., orthogonal) to that direction. In other words, the adhesive surface of the aforementioned transparent component can have a two-dimensional or three-dimensional structure.

[0325] The adhesive sheet disclosed herein is preferably used in portable electronic devices. In these portable electronic devices, it is preferably used for attaching to transparent components or for fixing components, at least one of which is transparent. Furthermore, in these portable electronic devices, it is preferably used for attaching to image display surfaces, decorative surfaces, or colored surfaces. For example, the adhesive sheet disclosed herein can be preferably used to fix the image display surface, decorative surface, or colored surface of a component (e.g., a decorative film) to the inside of a transparent housing that is a transparent component. With this configuration, decorative surfaces, etc., can be visually identified from the outside of the housing; on the other hand, for example, when using a component with a colored surface, internal shielding can be provided, making it particularly suitable as an outer casing or other external structure.

[0326] The aforementioned examples of portable electronic devices, without limitation, include mobile phones, smartphones, tablet PCs, laptop PCs, various wearable devices (such as wristwatches, modular devices worn on the wrist, and those attached to the body via clips or straps; eyewear (monocular, binocular, and helmet-type); clothing devices attached to shirts, socks, hats, etc., as accessories; and earwear such as headphones), digital cameras, digital camcorders, audio equipment (portable music players, voice recorders, etc.), calculators (desktop calculators, etc.), portable gaming devices, electronic dictionaries, electronic notebooks, e-books, in-vehicle information devices, portable radios, portable televisions, portable printers, portable scanners, portable modems, etc. It should be noted that in this specification, "portable" is not adequately interpreted as merely being able to carry; it refers to a level of portability that allows a standard adult to move it relatively easily.

[0327] It should be noted that the matters disclosed in this specification include the following solutions.

[0328] [1] An adhesive sheet with a release film, comprising: an adhesive sheet having an adhesive layer, and a release film laminated on the adhesive surface of the adhesive sheet.

[0329] The maximum height Rz of the adhesive side surface of the aforementioned release film is less than 400 nm.

[0330] [2] The adhesive sheet with a release film according to [1] above, wherein the arithmetic mean roughness Ra of the adhesive side surface of the release film is 30 nm or less.

[0331] [3] The adhesive sheet with a release film according to [1] or [2] above, wherein the release film has a peeling force of 1 N / 50 mm or less on the adhesive sheet.

[0332] [4] An adhesive sheet with a release film according to any one of [1] to [3] above, wherein the thickness of the release film is in the range of 50 to 125 μm.

[0333] [5] An adhesive sheet with a release film according to any one of [1] to [4] above, wherein the total light transmittance of the aforementioned adhesive sheet is 85% or more and the haze value is 1% or less.

[0334] [6] An adhesive sheet with a release film according to any one of [1] to [5] above, wherein the adhesive sheet is an adhesive sheet having the aforementioned adhesive layer and a supporting substrate laminated on one side of the adhesive layer with one-sided adhesiveness.

[0335] [7] An adhesive sheet with a release film according to any one of [1] to [5] above, wherein the aforementioned adhesive sheet is an adhesive sheet having double-sided adhesive properties having a first adhesive surface and a second adhesive surface.

[0336] The aforementioned release film includes a first release film disposed on the first adhesive surface and a second release film disposed on the second adhesive surface.

[0337] The maximum height Rz1 of the first adhesive side surface S1 of the first peeling film and the maximum height Rz2 of the second adhesive side surface S2 of the second peeling film are both below 400 nm.

[0338] [8] An adhesive sheet with a release film according to any one of [1] to [5] above, wherein the aforementioned adhesive sheet is an adhesive sheet having double-sided adhesive properties having a first adhesive surface and a second adhesive surface.

[0339] The aforementioned release film is a double-sided release film with a first release surface and a second release surface.

[0340] The maximum height Rz1 of the first peeling surface of the aforementioned peeling film and the maximum height Rz2 of the second peeling surface of the aforementioned peeling film are both below 400 nm.

[0341] [9] An adhesive sheet with a release film according to any one of [1] to [8] above, wherein the aforementioned adhesive layer is an acrylic adhesive layer.

[0342]

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

[0343]

[11] An adhesive sheet with a release film according to any one of [1] to

[10] above, wherein the storage modulus of the aforementioned adhesive sheet at 25°C is 4 × 10⁻⁶. 4 Pa or above.

[0344]

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

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

[0345]

[13] An adhesive sheet with a release film according to any one of [1] to

[12] above, wherein the elastic modulus of the aforementioned adhesive sheet, as determined by the tensile test described below, is 3.0 MPa or more.

[0346] [Tension Test]

[0347] Regarding the adhesive layer of the aforementioned adhesive sheet, with an illuminance of 300 mW / cm² 2 Cumulative light intensity 3000 mJ / cm 2 After being irradiated with ultraviolet light and cured at 50°C for 48 hours, the aforementioned adhesive layer was cut into pieces with a width of 10 mm and a length of 150 mm to prepare test specimens. Tensile tests were conducted on the specimens using a tensile testing machine at 23°C and 50%RH with a chuck spacing of 120 mm and a tensile speed of 50 mm / min. The stress-displacement curve was obtained, and the elastic modulus [MPa] was calculated from its initial slope.

[0348]

[14] An adhesive sheet with a release film according to any one of [1] to

[13] above, wherein the impact resistance of the aforementioned adhesive sheet, as determined by the following shear impact test, is 2.0 J / 10 mm. 2 above.

[0349] [Shear Impact Test]

[0350] Shear impact tests were performed using a pendulum-type adhesive shear impact testing machine based on JIS K6855. The following sample was used as the test specimen: a 10mm square piece of the aforementioned adhesive sheet was bonded to the center of a 25mm square, 1.7mm thick chemically strengthened glass plate. Then, the second side of the aforementioned adhesive sheet was bonded to the center of a 40mm square stainless steel plate (SUS304BA plate) and pressed under a 5N load for 10 seconds. Following this, the plate was autoclaved (50°C, 0.5MPa, 15 minutes) with an illuminance of 300mW / cm² from the glass plate side. 2 Cumulative light intensity 3000 mJ / cm 2 The sample was obtained by irradiating it with ultraviolet light under certain conditions and then curing it at 50°C for 48 hours.

[0351] The aforementioned test sample was fixed with the stainless steel plate as the lower side. The absorbed energy [J] when the glass plate was struck by a hammer with a hammer energy of 2.75 J and a hammer speed of 3.5 m / s at 23°C and 50% RH was measured. The impact resistance [J / 10mm] was then determined. 2 ].

[0352]

[15] An adhesive sheet with a release film according to any one of [1] to

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

[0353]

[16] According to the adhesive sheet with a release film described in

[15] above, wherein the aforementioned photoreactive monomer (B) comprises a compound B1 having an intramolecular ring structure and two or more olefinic unsaturated groups, wherein the molecular weight of the compound B1 relative to each of the aforementioned olefinic unsaturated groups is 100 g / mol or more.

[0354]

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

[16] above, wherein the compound B1 contains at least one structure selected from the group consisting of bisphenol A, bisphenol F and bisphenol E within the molecule.

[0355]

[18] An adhesive sheet with a release film according to

[16] or

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

[0356]

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

[16] to

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

[0357]

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

[16] to

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

[0358]

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

[16] to

[20] above, wherein the adhesive layer comprises the above-mentioned compound B1 and compound B2 having two or more functional groups and no intramolecular ring structure as the above-mentioned photoreactive monomer (B).

[0359]

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

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

[0360]

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

[21] or

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

[0361]

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

[21] to

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

[0362]

[25] An 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 adhesive layer is 1 part by weight or more and 80 parts by weight or less relative to 100 parts by weight of the polymer (A).

[0363]

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

[15] to

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

[0364]

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

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

[0365]

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

[15] to

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

[0366]

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

[15] to

[28] above, wherein the adhesive layer is cross-linked using a cross-linking agent.

[0367]

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

[15] to

[29] above, wherein the adhesive layer comprises a photopolymerization initiator.

[0368]

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

[15] to

[30] above, wherein the adhesive layer comprises a silane coupling agent.

[0369]

[32] An adhesive sheet with a release film according to any one of [1] to

[31] above, wherein the adhesive sheet has an adhesive force of 1.0 N / 20 mm or more to glass.

[0370]

[33] An adhesive sheet with a release film according to any one of [1] to

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

[0371]

[34] An adhesive sheet roll with a release film is formed by winding the adhesive sheet with a release film as described in any one of [1] to

[33] above.

[0372] Example

[0373] The following describes several embodiments of the present invention, but it is not intended to limit the invention to the solutions shown in the embodiments. It should be noted that, in the following description, "parts" and "%" are based on weight unless otherwise specified.

[0374] <Evaluation Methods>

[0375] [Total transmittance and haze value]

[0376] Peel off one side of the release film from the adhesive sheet with the release film attached, and attach it to a glass slide (Matsunami Glass Industry Co., Ltd., trade name "Shiromazuki No.1", thickness 0.8~1.0 mm, total transmittance 92%, haze value 0.2%). Next, peel off the release film from the other side to prepare a test piece with the adhesive sheet / glass slide layer. Measure the total transmittance and haze value of the obtained test piece using a haze meter (device name "HM-150N", manufactured by Murakami Color Technology Research Institute). For the above measurements, the glass plate with the adhesive sheet attached can be configured such that the adhesive sheet is the light source side.

[0377] [Adhesion to glass]

[0378] The adhesive sheet with the release film was cut into pieces 100 mm long and 20 mm wide. Next, the release film was peeled off from one side of the adhesive sheet, and a PET film (trade name "Lumirror S-10", manufactured by Toray Industries, Ltd., 25 μm thick) was used as a backing. Then, the release film was peeled off from the other side (the testing side), and a 2 kg roller was used to press it onto a glass plate (trade name "Soda-lime Glass") used as a test plate. On a test plate (0050”, manufactured by Matsunami Glass Industry Co., Ltd.), a test piece consisting of a test plate, adhesive sheet, and PET film was prepared. The obtained test piece was subjected to autoclaving (50°C, 0.5MPa, 15 minutes), and then cooled for 30 minutes at 23°C and 50%RH. After cooling, the peel strength when peeling the adhesive sheet (test side) from the test plate was determined using a tensile testing machine (equipment name "Autograph AG-IS", manufactured by Shimadzu Corporation) according to JIS Z 0237, at 23°C and 50%RH, with a tensile speed of 300 mm / min and a peel angle of 180°. This was taken as the glass adhesion force [N / 20mm].

[0379] It should be noted that in the case of adhesive sheets protected by release films that are on both sides as peel surfaces, and in the case of single-sided adhesive sheets, there is no need for peeling of the release film on one side and the backing of the PET film.

[0380] [Peeling force of the peeling film]

[0381] The adhesive sheet with the release film was cut into pieces 150 mm long and 50 mm wide, fixed to a test plate, and the release film on the light peel side was peeled off from the adhesive sheet using a tensile testing machine (Autograph AG-IS, manufactured by Shimadzu Corporation) at 23°C and 50%RH, at a tensile speed of 300 mm / min and a peel angle of 180°. The highest value of the next 50 mm interval after the start of peeling was taken as the peel force (light peel side) [N / 50 mm].

[0382] Regarding the peel force of the release film on the heavily peeled side, the release film on the lightly peeled side of the adhesive sheet with the release film of the protective tape was peeled off. A PET film (trade name "Lumirror S-10", manufactured by Toray Industries, Ltd., thickness 25μm) was used as a backing. The PET film side was fixed to the test plate, and the release film on the heavily peeled side was peeled off from the adhesive sheet using a tensile testing machine (device name "Autograph AG-IS", manufactured by Shimadzu Corporation) at 23°C, 50%RH atmosphere, tensile speed of 300mm / min, and peel angle of 180°. The highest value of the next 50mm interval after the start of peeling was excluded as the peel force of the release film (heavily peeled side) [N / 50mm].

[0383] It should be noted that, in the case of adhesive sheets protected by release films that are on both sides as peel surfaces, and in the case of single-sided adhesive sheets, the peel force of the release film on one side can be measured in the same way as the peel force measurement of the release film on the light peel side, without the need for a PET film backing.

[0384] [Arithmetic mean roughness (Ra) and maximum height (Rz)]

[0385] The arithmetic mean roughness (Ra) and maximum height (Rz) of the adhesive surface of the adhesive sheet were measured as follows. Under the above-mentioned conditions for measuring the peel force of the release film, the release film was peeled from the adhesive sheet with the release film at a peel angle of 180° and a speed of 300 mm / min. After standing for 30 minutes, the surface shape of the exposed adhesive surface was measured using a three-dimensional optical profilometer (trade name "NewView7300", manufactured by ZYGO) at 23°C and 50%RH.

[0386] The arithmetic surface roughness Ra was calculated from the measured data according to JIS B 0601-2001. Furthermore, the maximum height (Rz) was calculated as the sum of the height Rp of the highest peak on the upper side of the roughness curve (from the average line of the roughness curve) and the depth Rv of the deepest valley on the lower side of the average line. The measurement conditions were as follows: Ra and Rz were measured 5 times (i.e., N=5), and their average values ​​were used.

[0387] (Measurement conditions)

[0388] Measurement area: 5.62mm × 4.22mm

[0389] (Objective lens: 2.5x, Endoscope: 0.5x)

[0390] Analysis Mode:

[0391] Remove: Cylinder

[0392] Data Fill: ON (Max: 25)

[0393] Remove Spikes: ON (xRMS: 1)

[0394] Filter: OFF

[0395] [Optical Distortion Evaluation]

[0396] A commercially available mirror (2mm thick) was prepared and manufactured on a plain glass plate using a silver-spraying method. The mirror was visually verified to be free of distortion, and a reflected image was projected onto a screen using the same method described later, confirming the absence of distortion. In a clean room, after removing foreign matter from the surface of the mirror with a clean cloth, the release film on one side of the adhesive sheet was peeled off. Appropriate tension was applied to adhere it to the surface of the mirror, ensuring no foreign matter, air bubbles, or distorted streaks were introduced. To remove the influence of micro-air bubbles, a degassing process was performed using a pressure degassing device (autoclave) (processing conditions: 50°C, 0.5MPa, 15 minutes). After cooling at room temperature for at least 30 minutes, the release film on the other side was peeled off from the adhesive sheet, creating an optical distortion evaluation sample (a laminate formed by the adhesive sheet and the mirror). The evaluation sample was positioned such that its adhesive sheet side faced the point light source side at an angle of approximately 45 degrees relative to the light from the point light source. A white screen was placed in front of the light source to project the reflected image. As a point light source, the product "Xenon Lamp C2577" manufactured by Hamamatsu Photonics KK or an equivalent can be used. The point light source, the evaluation sample, and the screen are arranged such that the distance from the evaluation sample to the point light source and the distance from the evaluation sample to the screen are both approximately 50 cm.

[0397] The point light source is lit, and the image reflected from the sample and projected onto the screen is visually observed. The presence and level of optical distortion are then evaluated using the following three levels.

[0398] E: No optical distortion was observed.

[0399] A: Slight optical distortion was observed, but it is at a practically acceptable level.

[0400] P: Obvious optical distortion was observed.

[0401] [Elastic modulus based on tensile test]

[0402] Prepare test pieces by cutting adhesive sheets (adhesive layers) with release films into sizes of 10 mm wide and 150 mm long. Under an environment of 23°C and 50%RH, peel off two release films to expose the adhesive layer. Perform tensile tests on the test pieces using a tensile testing machine (device name "Autograph AG-IS", manufactured by Shimadzu Corporation) with a chuck distance of 120 mm and a tensile speed of 50 mm / min. Calculate the SS curve and the elastic modulus [MPa] from its initial slope (the elastic deformation region of the SS curve, specifically the slope within the range of displacement less than about 5%).

[0403] It should be noted that the thickness of the specimen used in the tensile test can be the same as or different from the thickness of the adhesive sheet (typically the adhesive layer). For example, if the thickness of the adhesive sheet is relatively small, to improve operability, the result of the tensile test can be obtained by using a specimen prepared with a thickness of 5 μm or more (e.g., about 5 μm to 200 μm) as the elastic modulus of the adhesive sheet. Regarding the thickness of the specimen, for example, for a photocurable adhesive sheet, it can be adjusted by appropriately overlapping the adhesive layer before UV irradiation. Alternatively, a specimen with a thickness suitable for tensile testing can be prepared using the same adhesive composition as that used to form the adhesive layer of the test object, and the result of the tensile test can be obtained as the elastic modulus of the adhesive layer. For example, a specimen with a thickness of about 10 μm to 50 μm (preferably about 15 μm to 25 μm) can be used for the tensile test.

[0404] [Impact resistance]

[0405] Shear impact tests were performed using a pendulum-type adhesive shear impact testing machine based on JIS K 6855. The following sample was used as the test specimen: an adhesive sheet with a release film was cut into 10mm squares. One side of the release film was peeled off to expose the first adhesive surface. This first adhesive surface was then attached to the center of a 25mm square, 1.7mm thick chemically strengthened glass plate (made by Corning Incorporated). The other side of the release film was then peeled off to expose the second adhesive surface. This second adhesive surface was then attached to the center of a 40mm square stainless steel plate (SUS304BA plate) and pressed under a 5N load for 10 seconds. Following this, an autoclave treatment was performed (50°C, 0.5MPa, 15 minutes). A high-pressure mercury lamp with an illuminance of 300mW / cm² was used from the glass plate side. 2 Cumulative light intensity 3000 mJ / cm 2 The sample was obtained by irradiating it with ultraviolet light under certain conditions and then curing it at 50°C for 48 hours.

[0406] The test sample was fixed with the stainless steel plate as the bottom side. Under conditions of 23°C and 50% RH, the absorbed energy [J] was measured when a hammer struck the outer periphery of the glass plate with a hammer energy of 2.75 J and a hammer velocity (impact velocity) of 3.5 m / s. The impact resistance [J / 10mm] was then determined. 2 The measurement was performed three times, and the arithmetic mean of the measurements was used.

[0407] It should be noted that in the case of adhesive sheets protected by a release film that serves as the peeling surface on both sides, the measurement can be performed in the same manner as described above, except that the peeling release film is a single sheet.

[0408] It should be noted that the adhesive sheet disclosed herein includes adhesive sheets in the form of adhesive layers that are light-cured after being bonded to the substrate. Therefore, at least for light-curable adhesive sheets (such as the adhesive sheet of Example 4 having adhesive C described later), an illuminance of 300 mW / cm² is used. 2 Cumulative light intensity 3000 mJ / cm 2 The above measurements (total transmittance, haze value, adhesion to glass, arithmetic mean roughness (Ra) and maximum height (Rz) of the bonded surface, optical distortion evaluation, and elastic modulus based on tensile test) were performed on the sample after it was irradiated with ultraviolet light under the above conditions. Regarding the adhesion to glass, the measurements were performed after the photocurable adhesive sheet (e.g., the adhesive sheet of Example 4 with adhesive C described later) was pressed onto the test plate and then irradiated with ultraviolet light under the above conditions. In addition, when the release film is transparent, the above ultraviolet irradiation treatment is preferably performed when the adhesive sheet (typically the adhesive layer) is sandwiched between the transparent release film.

[0409] Regarding the illuminance / light intensity of the light source, ideally, an industrial UV inspector (model "UVR-T2", light-receiving part "UD-T36T2", manufactured by TOPCON) should be used to measure the actual distance between the light source and the sample.

[0410] <Example 1>

[0411] (Preparation of adhesive composition)

[0412] 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), and 0.075 parts of the photopolymerization initiators "Irgacure 651" (manufactured by BASF) and "Irgacure 184" (manufactured by BASF) were mixed and then exposed to ultraviolet light under a nitrogen atmosphere to undergo partial photopolymerization, thereby obtaining a partial polymer (acrylic polymer slurry) with a polymerization rate of approximately 10%. 0.14 parts of dipentaerythritol hexaacrylate (trade name "KAYARAD DPHA", manufactured by Nippon Kayaku Co., Ltd.) and 0.3 parts of silane coupling agent (trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) were added to 100 parts of the obtained acrylic polymer slurry and mixed uniformly to obtain acrylic adhesive composition A.

[0413] (Making of adhesive sheets)

[0414] As the first release film, a PET release film with a thickness of 75 μm, consisting of a surface S1 (first adhesive surface side surface) prepared to be laminated onto the first adhesive surface of the adhesive sheet, is prepared to be a release surface based on a silicone-based release agent. This surface S1 has a Ra of 18 nm and a Rz of 223 nm. As the second release film, a PET release film with a thickness of 100 μm, consisting of a surface S2 (second adhesive surface side surface) prepared to be laminated onto the second adhesive surface of the adhesive sheet, is prepared to be a release surface based on a silicone-based release agent. This surface S2 has a Ra of 18 nm and a Rz of 223 nm.

[0415] The aforementioned acrylic adhesive composition A is applied to the first adhesive-side surface S1 of the first release film, with a thickness of 100 μm after adhesive layer formation, to form an adhesive composition layer. Then, the second release film is covered on the surface of this adhesive composition layer with its second adhesive-side surface S2 becoming the adhesive composition layer side. This isolates the adhesive composition layer from oxygen. Then, an illuminance of 5 mW / cm² is applied. 2 Light intensity 2000mJ / cm 2 The adhesive composition layer is photocured under ultraviolet light under specific conditions to produce a substrate-free double-sided adhesive sheet consisting only of an acrylic adhesive layer (also known as Adhesive A) and with each side of the acrylic adhesive layer protected by a first release film and a second release film. It should be noted that the weight-average molecular weight (Mw) of the acrylic polymer used as the base polymer in the adhesive layer is 2 million.

[0416] <Example 2>

[0417] As the first and second release films, release films having surfaces S1 and S2 having Ra and Rz as shown in Table 1 were used respectively. Additionally, the thickness of the adhesive layer was changed to 25 μm. Otherwise, the substrate-free double-sided adhesive sheet of this example was fabricated using the same procedure as in Example 1 above.

[0418] <Example 3>

[0419] The monomer composition was changed to 68 parts of 2-ethylhexyl acrylate (2EHA), 15 parts of N-vinyl-2-pyrrolidone (NVP), and 17 parts of HEA. Otherwise, the same procedure as in Example 1 was followed to prepare an acrylic polymer slurry. Using this acrylic polymer slurry, the same procedure as in Example 1 was followed to obtain acrylic adhesive composition B. Using the obtained acrylic adhesive composition B, the thickness of the adhesive layer (also called adhesive B) was set to 50 μm. Otherwise, the same procedure as in Example 2 was followed to prepare the substrate-free double-sided adhesive sheet of this example.

[0420] <Example 4>

[0421] (Preparation of adhesive composition)

[0422] In a reaction vessel equipped with a cooling pipe, a nitrogen inlet pipe, a thermometer, and a stirring device, 60 parts of BA, 6 parts of CHA, 18 parts of NVP, 1 part of isostearyl acrylate (iSTA), and 15 parts of 4HBA were added 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, making the monomer composition 45%. Nitrogen gas was purged while stirring for approximately 1 hour. Then, the reaction vessel was heated to 60°C and the reaction was carried out for 7 hours to obtain an acrylic polymer with a weight-average molecular weight (Mw) of 350,000. In a solution of the acrylic polymer (100 parts solids), 0.1 parts of trimethylolpropane / phenylenediamine diisocyanate adduct (manufactured by Mitsui Chemicals Co., Ltd., trade name "Takenate D-110N", solids concentration 75%) as an isocyanate-based crosslinking agent and dioctyltin dilaurate (Tokyo Fine Chemical Co., Ltd., trade name "EMBILIZER") as a crosslinking accelerator were added. The adhesive composition C of this example is prepared by uniformly mixing 0.01 parts of OL-1, 4 parts of acetylacetone as a crosslinking delay agent, 0.3 parts of 3-epoxypropoxypropyltrimethoxysilane (trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent, 8 parts of dipentaerythritol hexaacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name "A-DPH") and 12 parts of tricyclodecanediethanol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name "A-DCP") as a photoreactive monomer, and 0.7 parts of 1-hydroxycyclohexylphenyl ketone (manufactured by IGM Regins, trade name "Omnirad184") as a photopolymerization initiator.

[0423] (Making of adhesive sheets)

[0424] As the first and second release films, release films having surfaces S1 and S2 having Ra and Rz as shown in Table 1 are used respectively.

[0425] The obtained adhesive composition C is coated onto the first adhesive side surface S1 of the first release film to a dried thickness of 20 μm. It is then heated and dried at 60°C for 1 minute under normal pressure and at 120°C for 3 minutes, followed by curing at 23°C for 120 hours to form a photocurable adhesive layer (substrate-free double-sided adhesive sheet). The second adhesive side surface S2 of the second release film is then bonded to the surface of this photocurable adhesive layer for protection. Thus, a substrate-free double-sided adhesive sheet is prepared, consisting only of a photocurable acrylic adhesive layer (also called adhesive C) and with each side of the photocurable acrylic adhesive layer protected by the first and second release films.

[0426] <Example 5>

[0427] As the first and second release films, release films having surfaces S1 and S2 having Ra and Rz as shown in Table 1 were used respectively. Additionally, the thickness of the adhesive layer was changed to 100 μm. Otherwise, the substrate-free double-sided adhesive sheet of this example was fabricated using the same procedure as in Example 3 above.

[0428] <Examples 6~7>

[0429] As the first and second release films, release films having surfaces S1 and S2 having Ra and Rz as shown in Table 1 were used respectively. Furthermore, for Example 6, the thickness of the adhesive layer was changed to 25 μm. Otherwise, the substrate-free double-sided adhesive sheets for each example were fabricated using the same procedure as in Example 1.

[0430] <Evaluation>

[0431] For each example of the adhesive sheet with a release film, the total transmittance [%], haze value [%], adhesion force to glass [N / 20mm], peel force of the release film [N / 50mm], arithmetic mean roughness (Ra) of the adhesive surface [nm], maximum height (Rz) [nm], and optical distortion were evaluated. The results are shown in Table 1. In addition, the elastic modulus based on tensile testing was measured for the adhesive sheet of Example 4, and impact resistance testing was performed on the adhesive sheets of Examples 1 to 4. A summary of each example is also shown in Table 1 (release surface Ra, Rz of the release film, type of adhesive, thickness of the adhesive sheet [μm], storage modulus at 25°C [Pa], gelation rate [%]).

[0432] Table 1

[0433]

[0434] As shown in Table 1, in Examples 1-5, the maximum height Rz of the adhesive side surface of the release film was 400 nm or less. For these examples, no optical distortion was observed after the release film was peeled off, or the optical distortion was within a practically acceptable range. Furthermore, the arithmetic mean roughness Ra of the adhesive side surface of the release film in these examples was 30 nm or less, and the peeling force of the release film was 1 N / 50 mm or less. On the other hand, in Examples 6-7, the maximum height Rz of the adhesive side surface of the release film exceeded 400 nm, and unevenness was observed in the optical distortion evaluation. It should be noted that the elastic modulus of the adhesive sheet in Example 4, based on the tensile test, was 3.0 MPa or more, and the impact resistance of the adhesive sheets in Examples 1-4 was 2.0 J / 10 mm. 2 above.

[0435] The specific examples of the present invention have been described in detail above, but they are merely examples and do not limit the scope of the claims. The solutions described in the claims include solutions derived from various modifications and alterations of the specific examples described above.

Claims

1. An adhesive sheet with a release film, comprising: an adhesive sheet having an adhesive layer, and a release film laminated on the adhesive surface of the adhesive sheet. in, The adhesive sheet is an adhesive sheet with one-sided adhesive properties, having the adhesive layer and a supporting substrate laminated on one side of the adhesive layer. The total light transmittance of the adhesive sheet is above 85%, and the haze value is below 1%. The maximum height Rz of the adhesive side surface of the release film is below 240 nm.

2. The adhesive sheet with a release film according to claim 1, wherein, The arithmetic mean roughness Ra of the surface of the peeling film is less than 30 nm.

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

4. The adhesive sheet with a release film according to claim 1 or 2, wherein, The thickness of the release film is in the range of 50~125μm.

5. The adhesive sheet with a release film according to claim 1 or 2, wherein, The adhesive layer is an acrylic adhesive layer.

6. The adhesive sheet with a release film according to claim 1 or 2, wherein, The gelation rate of the adhesive layer is 30-95% by weight.

7. The adhesive sheet with a release film according to claim 1 or 2, wherein, The energy storage modulus of the adhesive layer at 25°C is 4×10⁻⁶. 4 Pa or above.

8. The adhesive sheet with a release film according to claim 1 or 2, wherein, The thickness of the adhesive sheet is 5~100μm.

9. The adhesive sheet with a release film according to claim 1 or 2, wherein, The elastic modulus of the adhesive sheet, as determined by the following tensile test, is 3.0 MPa or higher. The tensile test is as follows: For the adhesive layer of the adhesive sheet, with an illuminance of 300 mW / cm² 2 Cumulative light intensity 3000 mJ / cm 2 After being irradiated with ultraviolet light and cured at 50°C for 48 hours, the adhesive layer was cut into pieces with a width of 10 mm and a length of 150 mm to make test pieces. The test pieces were subjected to tensile tests using a tensile testing machine at 23°C and 50%RH with a chuck spacing of 120 mm and a tensile speed of 50 mm / min. The stress-displacement curve was obtained, and the elastic modulus [MPa] was calculated from its initial slope.

10. The adhesive sheet with a release film according to claim 1 or 2, wherein, The adhesive layer contains a polymer (A) and a photoreactive monomer (B).

11. The adhesive sheet with a release film according to claim 10, wherein, The photoreactive monomer (B) comprises a compound B1 having an intramolecular ring structure and two or more olefinic unsaturated groups, wherein the molecular weight of compound B1 relative to each of the olefinic unsaturated groups is 100 g / mol or more.

12. The adhesive sheet with a release film according to claim 1 or 2, used to fix a component having an image display surface, a decorative surface or a colored surface to a transparent component.

13. A roll of adhesive sheet with a release film, which is formed by winding the adhesive sheet with a release film according to any one of claims 1 to 12.

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