CN113462313A

CN113462313A - Pressure-sensitive adhesive sheet with release film

Info

Publication number: CN113462313A
Application number: CN202110342365.2A
Authority: CN
Inventors: 形见普史; 西丸步; 野中崇弘
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2020-03-31
Filing date: 2021-03-30
Publication date: 2021-10-01
Also published as: JP2021161192A; KR20210122175A; SG10202103241WA; TW202138512A

Abstract

Provided is an adhesive sheet with a release film. Provided is an adhesive sheet having an adhesive surface with high surface smoothness. According to the present specification, there is provided a release film-equipped adhesive sheet comprising an adhesive sheet and a release film laminated on the adhesive surface of the adhesive sheet. The maximum height Rz of the pressure-sensitive adhesive surface side of the release film-equipped pressure-sensitive adhesive sheet is 400nm or less.

Description

Pressure-sensitive adhesive sheet with release film

Technical Field

The present invention relates to a pressure-sensitive adhesive sheet with a release film.

Background

In general, an adhesive (also referred to as a pressure-sensitive adhesive, hereinafter the same) 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 utilizing such properties, adhesives are widely used in various industrial fields such as home electric appliances, automobiles, OA equipment, and the like, typically in the form of an adhesive sheet comprising a layer of the adhesive.

In the above-mentioned pressure-sensitive adhesive sheet, a high degree of smoothness is sometimes required for the pressure-sensitive adhesive surface (surface of the pressure-sensitive adhesive layer). As an example of such a pressure-sensitive adhesive sheet, a pressure-sensitive adhesive sheet for optical use is cited. For example, japanese patent nos. 4673344 and 4805999 disclose that the surface roughness (Ra) of the pressure-sensitive adhesive layer of an optical pressure-sensitive adhesive sheet is in a predetermined range for the purpose of improving the visibility. Further, Japanese patent application laid-open No. 2017-105974 discloses that the ten-point average roughness of the pressure-sensitive adhesive surface of a pressure-sensitive adhesive sheet useful for optical applications is about 1000nm or less. Further, japanese patent No. 4069625 discloses 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 0.1 μm or less. Japanese patent No. 6300788 discloses that the surface roughness (Ra) and the maximum protrusion height (Rp) of the release film are within predetermined ranges.

Disclosure of Invention

In various products such as portable electronic devices, the adhesive sheet is used in a region visually recognized from the outside. For example, the adhesive sheet for portable electronic equipment may be used not only on the image display surface of the electronic equipment but also on a surface other than the image display surface (for example, the back surface). Therefore, the pressure-sensitive adhesive sheet used for this application is sometimes required to have high transparency so that the presence thereof is not perceived, and moreover, the pressure-sensitive adhesive surface is also required to have high smoothness. If orange peel or stripes are present on the pressure-sensitive adhesive surface, the visibility through the pressure-sensitive adhesive sheet is reduced, and the appearance design, the beauty and the high-grade feeling of the adherend surface may be impaired.

Although not particularly limited, one application in which a highly smooth adhesive surface is desired is as follows: a film having a design including a specific color tone such as a metal color tone is attached to the inside of a transparent case constituting a portable electronic device so that a design forming surface (decorative surface) thereof is on the transparent case side. In the pressure-sensitive adhesive sheet used for fixing the transparent case and the film, both pressure-sensitive adhesive surfaces are preferably highly smooth because both pressure-sensitive adhesive surfaces can affect the visibility. Even in the case of a pressure-sensitive adhesive sheet having smoothness which has been regarded as acceptable, optical distortion and the like are observed under more accurate evaluation conditions, and it cannot be said that the pressure-sensitive adhesive sheet has satisfactory surface smoothness. If a pressure-sensitive adhesive sheet having a more smooth pressure-sensitive adhesive surface can be realized, it is practically useful as a joining means which does not impair the appearance design, appearance and quality of an adherend.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an adhesive sheet having an adhesive surface with high surface smoothness in a form protected by a release film.

According to the present specification, there is provided an adhesive sheet with a release film. The pressure-sensitive adhesive sheet with a release film comprises: the pressure-sensitive adhesive sheet comprises a pressure-sensitive adhesive layer and a release film laminated on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet. The maximum height Rz of the pressure-sensitive adhesive surface side surface of the release film is 400nm or less.

According to the above configuration, the pressure-sensitive adhesive sheet has high surface smoothness because the pressure-sensitive adhesive surface is protected by the release film in a state of being in contact with the surface of the release film having a maximum height Rz of 400nm or less. Therefore, when the adhesive sheet is attached to an adherend, the surface to be adhered to the adherend has high surface smoothness, and adhesion free from optical distortion or suppressed in optical distortion can be realized.

In some preferred embodiments, the arithmetic average roughness Ra of the surface of the release film is 30nm or less. According to this configuration, a configuration having a pressure-sensitive adhesive surface with high surface smoothness can be preferably realized.

In some preferred embodiments, the peeling force of the peeling film to the pressure-sensitive adhesive sheet is 1N/50mm or less. With such a configuration, when the release film is removed from the pressure-sensitive adhesive surface during use of the pressure-sensitive adhesive sheet, fine waviness of the pressure-sensitive adhesive surface due to a so-called stick-slip phenomenon caused by peeling of the self-release film is suppressed, and thus a smoother pressure-sensitive adhesive surface is easily obtained.

In some preferred embodiments, the thickness of the release film is in the range of 50 to 125 μm. With such a configuration, the release film has a sufficient thickness, and an event (dent) that impairs the smoothness of the surface of the psa sheet beyond the release film can be prevented. Such an event may be caused by, for example, foreign matter mixed between the release films when the adhesive sheet with the release film is wound up into a roll. Further, by setting the thickness of the release film to a predetermined value or less, the removal from the adhesive sheet becomes smooth, and the adhesive surface of the adhesive sheet is likely to maintain high surface smoothness even after the release film is removed.

In some preferred embodiments, the total light transmittance of the pressure-sensitive adhesive sheet is 85% or more, and the haze value is 1% or less. The pressure-sensitive adhesive sheet satisfying the above characteristics is easy to visually recognize an adherend through the pressure-sensitive adhesive sheet, and does not impair the visual recognition such as appearance design of the adherend.

In some embodiments, the pressure-sensitive adhesive sheet is a one-sided adhesive pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer and a support base laminated on one side of the pressure-sensitive adhesive layer. The effects obtained by the techniques disclosed herein can be preferably achieved in a mode using a pressure-sensitive adhesive sheet having single-sided adhesiveness. In this embodiment, the support substrate may be a transparent substrate.

In some other embodiments, the psa sheet is a double-sided adhesive psa sheet having a 1 st adhesive surface and a 2 nd adhesive surface. The pressure-sensitive adhesive sheet with a release film includes, as release films, a 1 st release film disposed on the 1 st pressure-sensitive adhesive surface and a 2 nd release film disposed on the 2 nd pressure-sensitive adhesive surface. Further, the maximum height Rz of the 1 st adhesive surface side surface S1 of the 1 st release film₁And the maximum height Rz of the 2 nd adhesive surface side surface S2 of the 2 nd release film₂All of them are 400nm or less. The effects obtained by the techniques disclosed herein can also be preferably achieved in such a configuration. In this configuration, it is preferable that the arithmetic average roughness Ra of the surface S1 of the 1 st release film is₁And the arithmetic average roughness Ra of the surface S2 of the 2 nd release film₂All of them are 30nm or less. Further, the peeling force of the 1 st peeling film to the pressure-sensitive adhesive sheet and the peeling force of the 2 nd peeling film to the pressure-sensitive adhesive sheetThe peeling force of the pressure-sensitive adhesive sheet may be 1N/50mm or less. Further, the thickness of the 1 st release film and the thickness of the 2 nd release film may be in the range of 50 to 125 μm, respectively.

In still other aspects, the psa sheet is a double-sided adhesive psa sheet having a 1 st adhesive surface and a 2 nd adhesive surface. The release film has a double-sided releasability having a 1 st release surface and a 2 nd release surface. Further, the maximum height Rz of the first release surface 1 of the release film₁And the maximum height Rz of the 2 nd release surface of the release film₂All of them are 400nm or less. The effects obtained by the techniques disclosed herein can also be preferably achieved in such a configuration. In this configuration, it is preferable that the arithmetic average roughness Ra of the 1 st peeling surface₁And the arithmetic average roughness Ra of the 2 nd release surface₂All of them are 30nm or less. Further, the peeling force of the 1 st peeling surface with respect to the adhesive sheet and the peeling force of the 2 nd peeling surface with respect to the adhesive sheet may be both 1N/50mm or less.

In some preferred embodiments, the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer. When an acrylic pressure-sensitive adhesive is used, the intended adhesive properties and viscoelastic properties with excellent impact resistance can be achieved without using an additive component such as a softening agent which may cause a decrease in transparency or limiting the amount of the additive used, and thus transparency, adhesive properties and viscoelastic properties can be easily combined. Further, acrylic adhesives tend to have superior discoloration resistance compared to, for example, rubber adhesives, and are advantageous from the viewpoint of maintaining transparency for a long period of time.

In some preferred embodiments, the gel fraction of the pressure-sensitive adhesive layer is 30 to 95 wt%. When the gel fraction of the pressure-sensitive adhesive layer is 95 wt% or less, the pressure-sensitive adhesive sheet tends to have excellent level difference following properties. Therefore, the adhesive can be favorably adhered to the surface of an adherend having a level difference. For example, when a print such as a logo is formed on the surface of an adherend, the pressure-sensitive adhesive sheet can satisfactorily follow the unevenness of the print without impairing the visual recognition. Further, when the gel fraction of the pressure-sensitive adhesive layer is 30 wt% or more, good adhesive properties and viscoelastic properties tend to be easily exhibited. For example, when the pressure-sensitive adhesive layer having the above gel fraction is used, there is a tendency that dents are not easily generated and the deformation resistance is also excellent.

In some preferred embodiments, the storage modulus at 25 ℃ of the pressure-sensitive adhesive layer is 4 × 10⁴Pa or above. The pressure-sensitive adhesive layer having the storage modulus at 25 ℃ tends to have preferable heat resistance, and easily exhibits good pressure-sensitive adhesive properties such as deformation resistance.

In some preferred embodiments, the thickness of the pressure-sensitive adhesive sheet is 5 to 100 μm. The pressure-sensitive adhesive sheet having a thickness of 5 μm or more tends to have excellent level difference following properties and is likely to absorb deformation due to foreign matter or the like. Further, by setting the thickness to 100 μm or less, the adhesive sheet is less likely to be strained and high smoothness of the adhesive surface is easily obtained.

In some preferred embodiments, the adhesive sheet has an elastic modulus of 3.0MPa or more as measured by the following tensile test. By satisfying the above characteristics, the adhesive sheet can exhibit high deformation resistance.

[ tensile test ]

The adhesive layer of the adhesive sheet was irradiated with light at an illuminance of 300mW/cm²And a cumulative light amount of 3000mJ/cm²The adhesive layer was cut into a size of 10mm in width and 150mm in length after curing at 50 ℃ for 48 hours under irradiation with ultraviolet rays, thereby producing a test piece. The tensile test of the test piece was carried out under an environment of 23 ℃ and 50% RH using a tensile tester at a chuck-to-chuck distance of 120mm and a tensile speed of 50 mm/min to obtain a stress-displacement curve, and the elastic modulus [ MPa ] was calculated from the initial slope]。

In some preferred embodiments, the adhesive sheet has an impact resistance of 2.0J/10mm as measured by the shear impact test described below²The above. By satisfying the above characteristics, the adhesive sheet can exhibit high impact resistance. For example, an adhesive sheet satisfying the modulus property and the impact resistance property in the tensile test is preferably used for the purpose of, for example, bonding and fixing members because it has high deformation resistance and can form a bond having high impact resistance。

[ shear impact test ]

The shear impact test was carried out using a pendulum type bonding shear impact tester according to JIS K6855. As the measurement samples, the following samples were used: a10 mm square first surface of the adhesive sheet was bonded to a center portion of a 25mm square chemically strengthened glass plate having a thickness of 1.7mm, and a second surface of the adhesive sheet was bonded to a center portion of a 40mm square stainless steel plate (SUS304BA plate) and pressure-bonded under a load of 5N for 10 seconds, followed by autoclave treatment (50 ℃, 0.5MPa, 15 minutes) to obtain a sheet having an illuminance of 300mW/cm from the glass plate side²And a cumulative light amount of 3000mJ/cm²The conditions (2) were irradiated with ultraviolet rays, and then, aging was performed at 50 ℃ for 48 hours, thereby obtaining a sample.

The measurement sample was fixed so that the stainless steel plate was positioned on the lower side, and the energy absorption [ J ] of a hammer impact applied to the outer peripheral surface of the glass plate under conditions of a hammer energy of 2.75J and a hammer speed of 3.5 m/sec was measured at 23 ℃ and 50% RH]Thus, the impact resistance [ J/10mm ] was determined²]。

In some preferred embodiments, the pressure-sensitive adhesive layer contains a polymer (a) and a photoreactive monomer (B). More preferably, the photoreactive monomer (B) contains a compound B1 having a cyclic structure and 2 or more ethylenically unsaturated groups in a molecule, and the molecular weight of the compound B1 is 100g/mol or more per 1 ethylenically unsaturated group. When the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer is used, the pressure-sensitive adhesive sheet has high deformation resistance and can be suitably bonded with high impact resistance.

When the release film-equipped adhesive sheet disclosed herein is used, an adhesive sheet having both adhesive surfaces with high surface smoothness can be realized, and therefore, the release film-equipped adhesive sheet is preferably used for fixing a member having an image display surface, a decorative surface or a colored surface, which is often required to have high visibility, to a transparent member. For example, in a system of fixing a decorative surface of a decorative film to a transparent member, since optical distortion is suppressed by the adhesive sheet, the decorative surface is easily visually recognized through the adhesive sheet, and the adhesive sheet can function as a joining means which does not impair the design of the decorative surface and the appearance and high-quality feeling thereof.

The release film-equipped adhesive sheet disclosed herein may be provided in the form of a release film-equipped adhesive sheet roll obtained by winding the release film-equipped adhesive sheet. Such a wound body is easy to handle during storage and transportation, and is advantageous in terms of productivity.

Drawings

Fig. 1 is a schematic cross-sectional view showing a release film-attached adhesive sheet according to an embodiment.

Fig. 2 is a schematic cross-sectional view showing a release film-attached adhesive sheet according to another embodiment.

Detailed Description

Preferred embodiments of the present invention will be described below. It is to be noted that matters other than the matters specifically mentioned in the present specification and matters necessary for the practice of the present invention can be understood by those skilled in the art from the teaching of the practice of the invention described in the present specification and the technical common general knowledge at the time of application. The present invention can be implemented according to the contents disclosed in the present specification and the common technical knowledge in the field. In the following drawings, members and portions that exhibit the same function are sometimes described with the same reference numerals, and redundant description may be omitted or simplified. In addition, the embodiments described in the drawings are schematically illustrated for clearly explaining the present invention, and do not necessarily accurately show the size and scale of the product actually provided.

In the present specification, the "pressure-sensitive adhesive" refers to a material having 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 as described above. As used herein, an adhesive is exemplified by "C.A. Dahlquist," Adhesion: Fundamental and Practice, "McLaren&Sons, (1966) P.143 ", as defined above, can generally be such that the complex tensile modulus E is satisfied^*(1Hz)＜10⁷dyne/cm²A material having the above properties (typically, a material having the above properties at 25 ℃).

In the present specification, the "acrylic polymer" refers to a polymer derived from a monomer component containing more than 50% by weight of an acrylic monomer, and is also referred to as an acrylic polymer. The acrylic monomer is a monomer having at least 1 (meth) acryloyl group in 1 molecule. In the present specification, "(meth) acryloyl group" is used to generally mean an acryloyl group and a methacryloyl group. Likewise, "(meth) acrylate" is used in a generic sense to refer to both acrylates and methacrylates; "(meth) acrylic acid" is used in a generic sense to refer to both acrylic acid and (meth) acrylic acid.

In the present specification, "mass" and "weight" have the same meaning.

In the present specification, the "photoreactive monomer" is a compound having at least 1 functional group (photoreactive functional group) capable of being reacted by irradiation with light in a molecule, and typically a compound having at least 1 ethylenically unsaturated group in a molecule as the photoreactive functional group. The photoreactive monomer as referred to herein may be any monomer as long as it can react as a monomer, and may be a polymer such as an oligomer or a polymer (for example, a polymer having at least 1 ethylenically unsaturated group in the molecule).

In the present specification, "photocurable" refers to a property of being cured by irradiation with light such as ultraviolet light, and for example, a photocurable adhesive composition refers to a composition which is cured by photocuring to form an adhesive or an adhesive layer. The photocurable pressure-sensitive adhesive layer refers to a pressure-sensitive adhesive layer that can be cured by irradiation with light such as ultraviolet light, and is used as a term for the pressure-sensitive adhesive layer before photocuring of the pressure-sensitive adhesive layer that is completely cured by the photocuring. A photocurable adhesive sheet is used as a term referring to an adhesive sheet provided with such a photocurable adhesive layer.

< example of construction of pressure-sensitive adhesive sheet with Release film >

Fig. 1 illustrates a structure of the release film-attached pressure-sensitive adhesive sheet disclosed herein. The release film-attached pressure-sensitive adhesive sheet 1 includes a double-sided adhesive pressure-sensitive adhesive sheet 10, a 1 st release film 21, and a 2 nd release film 22. The adhesive sheet 10 has a 1 st adhesive surface 10a and a 2 nd adhesive surface 10b located on the opposite side of the 1 st adhesive surface 10 a. Since the psa sheet 10 of this embodiment is a substrate-less double-sided adhesive psa sheet comprising a psa layer 12, the 1 st psa surface 10a and the 2 nd psa surface 10b are the 1 st psa surface 12a and the 2 nd psa surface 12b, respectively, of the psa layer 12. The 1 st release film 21 is disposed on the 1 st adhesive surface 10a of the adhesive sheet 10, and one surface (the 1 st adhesive surface side surface S1)21a thereof is in releasable contact with the 1 st adhesive surface 10a of the adhesive sheet 10. The 2 nd release film 22 is disposed on the 2 nd adhesive surface 10b of the adhesive sheet 10, and one surface (the 2 nd adhesive surface side surface S2)22a thereof is in releasable contact with the 2 nd adhesive surface 10b of the adhesive sheet 10. The 1 st adhesive surface side (S1)21a of the 1 st release film 21 and the 2 nd adhesive surface side (S2)22a of the 2 nd release film 22 are release surfaces having a release treatment layer by, for example, a silicone-based release treatment agent. In this way, the release film-coated pressure-sensitive adhesive sheet 1 is in a form in which the 1 st pressure-sensitive adhesive surface 10a and the 2 nd pressure-sensitive adhesive surface 10b of the pressure-sensitive adhesive sheet 10 are protected by the 1 st release film 21 and the 2 nd release film 22, respectively. When the pressure-sensitive adhesive sheet 10 is used, the 1 st and 2

nd release films

21 and 22 are removed, and the 1 st and 2 nd pressure-

sensitive adhesive surfaces

10a and 10b are exposed and adhered to an adherend.

The release film-attached pressure-sensitive adhesive sheet 1 may be in the form of a roll (release film-attached pressure-sensitive adhesive sheet roll) 100 as shown in fig. 1. The pressure-sensitive adhesive sheet roll 100 is provided in a form in which the pressure-sensitive adhesive sheet 1 with a release film is wound around a core (core) 50.

Fig. 2 schematically shows the structure of a release film-equipped adhesive sheet according to another embodiment. The release film-attached pressure-sensitive adhesive sheet 2 shown in fig. 2 includes a single-sided adhesive pressure-sensitive adhesive sheet (single-sided pressure-sensitive adhesive sheet) 10 and a release film 21. The single-sided pressure-sensitive adhesive sheet 10 includes a pressure-sensitive adhesive layer 12 and a support base 14 supporting the pressure-sensitive adhesive layer 12, and has one surface (the 1 st surface 12a of the pressure-sensitive adhesive layer 12) serving as a pressure-sensitive adhesive surface 10a and the other surface serving as a back surface (non-pressure-sensitive adhesive surface). In this embodiment, the back surface of the adhesive sheet 10 is constituted by one surface (surface of the support substrate 14 opposite to the pressure-sensitive adhesive layer side surface 14 a) 14b of the support substrate 14. The 2 nd surface 12b of the pressure-sensitive adhesive layer 12 is fixed to the other surface (pressure-sensitive adhesive layer-side surface) 14a of the support base 14, and the pressure-sensitive adhesive layer-side surface 14a can be said to be a non-releasable surface (non-releasable surface). As such, the adhesive layer 12 is provided in a manner that is not intended to be separated from the support substrate 14. On the other hand, the surface (pressure-sensitive adhesive surface side surface S1)21a of the release film 21 serves as a release surface as in the case of the 1 st release film of fig. 1, and is in releasable contact with the pressure-sensitive adhesive surface 10a of the pressure-sensitive adhesive layer 12 to protect the pressure-sensitive adhesive surface 10 a. The psa sheet 2 with a release film may be provided in the form of a roll (psa sheet roll) 200 as shown in fig. 2. The pressure-sensitive adhesive sheet roll 200 has a form in which a pressure-sensitive adhesive sheet 2 with a release film is wound around a core (core) 50, the pressure-sensitive adhesive sheet 2 with a release film including a pressure-sensitive adhesive sheet 10 and a release film 21, the pressure-sensitive adhesive sheet 10 including a pressure-sensitive adhesive layer 12 and a support base 14.

Fig. 1 illustrates a roll 100 in which the psa sheet 1 with a release film is wound around a core 50, but the roll 100 may be in a form without the core 50, that is, in a so-called coreless roll in which the psa sheet 1 with a release film is wound alone. The same applies to the roll 200 shown in fig. 2.

The adhesive sheet 1 shown in fig. 1 (before use) has the following configuration: the 1 st adhesive surface 10a and the 2 nd adhesive surface 10b are protected by the 1 st release film 21 and the 2 nd release film 22, respectively, which have surfaces (release surfaces) having releasability at least on the adhesive surface side, but the following configuration may be adopted: the 2 nd release film 22 is omitted, and a film having both surfaces serving as release surfaces is used as the release film 21, and the pressure-sensitive adhesive sheet 1 is wound so that the 2 nd adhesive surface 10b is in contact with the back surface of the release film 21, whereby the 2 nd adhesive surface 10b is also protected by the release film 21.

The pressure-sensitive adhesive sheet may be a substrate-free pressure-sensitive adhesive sheet as shown in fig. 1, a substrate-attached one-sided pressure-sensitive adhesive sheet as shown in fig. 2, or a substrate-attached double-sided pressure-sensitive adhesive sheet. Specifically, the pressure-sensitive adhesive sheet may be a substrate-containing pressure-sensitive adhesive sheet in which a non-peelable substrate is embedded (embedded). As the substrate, a plastic film, paper, nonwoven fabric, or the like can be used. Further, although the pressure-sensitive adhesive layer 10 has a single-layer structure as illustrated in fig. 1 and 2, the structure of the pressure-sensitive adhesive layer 10 is not limited thereto. For example, the pressure-sensitive adhesive layer may include 2 or more sub pressure-sensitive adhesive layers formed of the same or different pressure-sensitive adhesives.

< peeling film >

(maximum height of adhesive surface side surface Rz)

The maximum height Rz of the pressure-sensitive adhesive surface side surface of the release film disclosed herein is 400nm or less. Thereby, the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet can have high surface smoothness. In the form in which the 1 st and 2 nd release films are disposed on the pressure-sensitive adhesive surfaces of the pressure-sensitive adhesive sheet, respectively, the maximum height Rz of the 1 st release film, i.e., the 1 st pressure-sensitive adhesive surface side surface S1₁And the maximum height Rz of the 2 nd adhesive surface side surface S2 of the 2 nd release film₂All of them are 400nm or less. Thus, each pressure-sensitive adhesive surface of the double-sided pressure-sensitive adhesive sheet has high surface smoothness, and both pressure-sensitive adhesive surfaces can exhibit high surface smoothness when attached to an adherend.

Maximum height Rz of the adhesive surface side surface of the release film (maximum height Rz of the 1 st adhesive surface side surface S1 including the 1 st release film)₁And the maximum height Rz of the 2 nd adhesive surface side surface S2 of the 2 nd release film₂. The same applies to the case where no particular description is given. ) Preferably about 340nm or less, more preferably about 280nm or less, and still more preferably about 240nm or less, and may be less than 200nm, may be less than 150nm, or may be less than 120 nm. In some embodiments, the maximum height Rz may be, for example, about 50nm or more, about 80nm or more, or about 100nm or more, from the viewpoint of ease of production of a release film, handleability, and the like. In the embodiment including the 1 st release film and the 2 nd release film, the maximum height Rz of the 1 st pressure-sensitive adhesive surface side surface S1 of the 1 st release film₁Maximum height Rz of the 2 nd adhesive surface side surface S2 of the 2 nd release film₂The levels may be the same or different.

(arithmetic average roughness Ra of adhesive surface side surface)

In addition, from the viewpoint of realizing a pressure-sensitive adhesive surface having high surface smoothness, the release film is preferably limited to have an arithmetic average roughness Ra of the pressure-sensitive adhesive surface side surface of a predetermined value or less (for example, about 100nm or less, and further less than 50 nm). In addition, in the adhesionIn the form of the 1 st and 2 nd release films disposed on the adhesive surfaces of the sheet, the arithmetic average roughness Ra of the 1 st release film surface S1₁And the arithmetic average roughness Ra of the 2 nd adhesive surface side surface S2 of the 2 nd release film₂It is suitable to be limited to, for example, about 100nm or less (and further less than 50 nm). In some aspects, the arithmetic average roughness Ra of the adhesive surface side surface of the release film (including the arithmetic average roughness Ra of the 1 st adhesive surface side surface S1 of the 1 st release film)₁And the arithmetic average roughness Ra of the 2 nd adhesive surface side surface S2 of the 2 nd release film₂. The same applies to the case where no particular description is given. ) Preferably about 30nm or less, may be about 25nm or less, may be about 20nm or less, and may be about 18nm or less. In some embodiments, the arithmetic average roughness Ra may be, for example, about 5nm or more, about 10nm or more, or about 15nm or more, from the viewpoint of ease of manufacturing a release film, handleability, and the like. In the embodiment comprising the 1 st release film and the 2 nd release film, the arithmetic average roughness Ra of the 1 st adhesive surface side surface S1 of the 1 st release film₁Arithmetic average roughness Ra of surface S2 of 2 nd adhesive surface of 2 nd release film₂The levels may be the same or different.

(surface Property of the Back surface)

The maximum height Rz and the arithmetic average roughness Ra of the back surface (the opposite surface to the pressure-sensitive adhesive layer side) of the release film (including the 1 st release film and the 2 nd release film) are not particularly limited. The maximum height Rz of the back surface of the release film (the surface opposite to the pressure-sensitive adhesive layer) may be more than 400nm (for example, about 500nm or more) or more than 800nm (for example, 1000nm or more) from the viewpoint of productivity and the like. The arithmetic average roughness Ra of the back surface of the release film (the surface opposite to the pressure-sensitive adhesive layer) may be more than 30nm (for example, more than 35nm, and further, about 50nm or more) from the viewpoint of productivity and the like.

The maximum height Rz and the arithmetic average roughness Ra of the surface of the peeled film can be adjusted by selecting a film material, a molding method, a surface treatment such as a peeling treatment, and the like. For example, there are mentioned adjustment of the smoothness of a layer (anti-blocking layer, hard coat layer, oligomer-preventing layer, etc.) constituting the releasable surface; reduction or non-use (non-particulation) of filler particles in the surface layer, release film substrate; and adjustment of stretching conditions.

The maximum height Rz and the arithmetic average roughness Ra of the surface of the peeled film were measured by using a non-contact surface roughness measuring apparatus. As the noncontact surface roughness measuring device, a surface roughness measuring device using an optical interference system, for example, a three-dimensional optical profiler (trade name "new view 7300", manufactured by ZYGO) or a product equivalent thereof can be used. For example, a glass plate (soda lime glass plate manufactured by MATSUNAMI, thickness 1.3 μm) was bonded and fixed to the surface of the release film opposite to the measurement surface with an adhesive, and the surface shape was measured using a three-dimensional optical profilometer (trade name "NewView 7300", manufactured by ZYGO) under an atmosphere of 23 ℃ and 50% RH. The same applies to the embodiments described later. The specific measurement conditions and calculation method are the same as those for the maximum height Rz and arithmetic mean roughness Ra of the pressure-sensitive adhesive sheet adhesive surface described in the examples below.

The release film (including the 1 st release film and the 2 nd release film, the same applies hereinafter unless otherwise specified) may be selected from those having a maximum height Rz of the adhesive surface side surface of 400nm or less. Non-limiting examples of release films that can be used include: a release film having a release treatment layer on a surface of a release film base; and a release film made of a low-adhesion resin such as a fluorine-based polymer (e.g., polytetrafluoroethylene) or a polyolefin-based resin (e.g., polyethylene or polypropylene).

As the release film disclosed herein, a release film having a release treatment layer on a release film base material can be preferably used. The release treatment layer may be formed by surface-treating a release film base with a release treatment agent. The release agent may be a known release agent such as a silicone release agent, a long chain alkyl release agent, a fluorine release agent, or molybdenum (IV) sulfide. In some embodiments, a release film having a release treatment layer based on a silicone-based release treatment agent is preferably used. The thickness and the forming method of the release treatment layer are not particularly limited, and may be set so as to exhibit appropriate releasability on the pressure-sensitive adhesive surface side of the release film.

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

Examples of the material of the plastic film include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), polyolefin resins such as Polyethylene (PE), polypropylene (PP), ethylene-propylene copolymers, and ethylene-butene copolymers, cellulose resins such as cellulose triacetate, acetate resins, polysulfone resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, cyclic polyolefin resins such as norbornene resins, (meth) acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl alcohol resins, ethylene-vinyl acetate copolymer resins, ethylene-vinyl alcohol copolymer resins, polyarylate resins, and the like, Polyphenylene sulfide resins, and the like. A release film substrate formed of a mixture of 1 or 2 or more of any of these resins may be used. Among them, preferable examples of the release film substrate include a polyester resin film (for example, a PET film) made of a polyester resin.

The plastic film used as the base material of the release film may be any of an unstretched film, a uniaxially stretched film, and a biaxially stretched film. The plastic film may have a single-layer structure or a multilayer structure including 2 or more sublayers. The plastic film may contain known additives useful for a release film substrate of an adhesive sheet, such as an antioxidant, an anti-aging agent, a heat stabilizer, a light stabilizer, an ultraviolet absorber, a colorant such as a pigment or a dye, a lubricant, a filler, an antistatic agent, and a nucleating agent. In the multilayer-structured plastic film, each additive may be compounded in all of the sub-layers, or may be compounded in only a part of the sub-layers.

In some preferred embodiments, the release film base (typically, a plastic film) is preferably a release film base in which the content of particles such as inorganic particles (for example, pigments, lubricants, fillers, and the like) in a layer on the release surface side is limited or substantially free of such particles. The term "substantially free" means that the amount of particles (for example, inorganic particles) in the layer is less than 1 wt%, preferably less than 0.1 wt% (for example, 0 to 0.01 wt%). In the release film provided with such a release film base material, the maximum height Rz and the arithmetic mean roughness Ra of the release surface tend to be low. In the case where the release film substrate (typically, a plastic film) has a multilayer structure, the content of particles in the layer on the release surface side may be 1/10 or less (for example, 1/50 or less) of the content of particles in the layers other than the release surface side layer.

In the embodiment including the 1 st release film and the 2 nd release film, the 1 st release film and the 2 nd release film may have the same material and composition or may have different materials and compositions.

The thickness of the release film is not particularly limited, and may be, for example, about 10 μm to 500. mu.m. From the viewpoint of strength and dimensional stability of the release film, the thickness of the release film is suitably 20 μm or more, preferably 30 μm or more, and may be 35 μm or more, and may be 40 μm or more, and may be 45 μm or more. In some preferred embodiments, the thickness of the release film is about 50 μm or more, may be about 60 μm or more, and may be about 70 μm or more. Thus, the release film has a sufficient thickness, and the occurrence of a defect (dent) in the smoothness of the surface of the pressure-sensitive adhesive sheet beyond the release film can be prevented. From the viewpoint of handling properties (e.g., ease of winding) of the release film, the thickness of the release film is preferably 300 μm or less, more preferably 250 μm or less, and may be 200 μm or less, 150 μm or less, and 130 μm or less. In some preferred embodiments, the thickness of the release film is about 125 μm or less, may be about 115 μm or less, may be about 105 μm or less, and may be about 90 μm or less. When the thickness of the release film is set to a predetermined value or less, a curl mark is less likely to occur when the release film is rolled up, the release from the adhesive sheet is smooth, and the adhesive surface of the adhesive sheet is likely to maintain high surface smoothness even after the release film is removed.

In the embodiment including the 1 st release film and the 2 nd release film, the thicknesses of the 1 st release film and the 2 nd release film may be the same or different. From the viewpoint of peeling workability, the 1 st release film and the 2 nd release film preferably have different thicknesses, and the thicker release film preferably has a thickness of about 1.1 times or more, for example, about 1.25 times or more, the thickness of the thinner release film.

On the back surface of the release film, a carrier or auxiliary film may be attached as necessary. The presence of such a back surface auxiliary film makes it easy to prevent dents even in a system using a thin release film, for example, and improves workability in punching and the like. As such a back auxiliary film, a known or conventional adhesive tape with a resin film substrate can be used.

< peeling force to peel off film >

In the release film-equipped pressure-sensitive adhesive sheet disclosed herein, the peel strength of the release film with respect to the pressure-sensitive adhesive sheet is preferably limited to a predetermined value or less. Thus, when the release film is removed from the pressure-sensitive adhesive surface during use of the pressure-sensitive adhesive sheet, fine waviness of the pressure-sensitive adhesive surface due to a so-called stick-slip phenomenon caused by the release of the self-release film is suppressed, and a smoother pressure-sensitive adhesive surface is easily obtained. In some preferred embodiments, the peeling force of the release film is about 1N/50mm or less, more preferably less than 0.90N/50mm, still more preferably less than 0.70N/50mm, particularly preferably less than 0.50N/50mm, and may be less than 0.40N/50mm, or less than 0.30N/50mm, or less than 0.20N/50mm, or less than 0.10N/50 mm. The lower limit of the peeling force of the peeling film is, for example, 0.01N/50mm or more, and may be 0.05N/50mm or more from the viewpoint of protection and prevention of floating of the peeling film. The peeling force of the release film can be adjusted by a peeling treatment or the like of the surface of the release film.

In the embodiment including the 1 st release film and the 2 nd release film, it is preferable that the peeling force of the 1 st release film with respect to the pressure-sensitive adhesive sheet and the peeling force of the 2 nd release film with respect to the pressure-sensitive adhesive sheet are different from each other from the viewpoint of peeling workability. For example, the peeling force of the peeling film on the heavy peeling side (for example, the 2 nd peeling film) is suitably about 1.2 times or more, preferably about 1.4 times or more, and may be about 1.5 times or more, and may be about 1.8 times or more, the peeling force of the peeling film on the light peeling side (for example, the 1 st peeling film). From the viewpoint of maintaining the light peelability, the peeling force of the peeling film on the heavy peeling side (for example, the 2 nd peeling film) is suitably about 3 times or less, and may be about 2 times or less, as compared with the peeling force of the peeling film on the light peeling side (for example, the 1 st peeling film).

The peel force of the release film was measured by preparing an adhesive sheet with a peel film cut to a length of 150mm and a width of 50mm, and measuring the peel force at a tensile rate of 300 mm/min and a peel angle of 180 ℃ in an atmosphere of 23 ℃ and 50% RH. Specifically, the measurement was carried out by the method described in the examples below.

< adhesive sheet >

(surface Property of adhesive surface)

The adhesive sheet disclosed herein has an adhesive surface whose maximum height Rz is limited to a predetermined value or less. When the adhesive surface is designed so that the maximum height Rz is low, the surface smoothness is high, and optical distortion is not generated or suppressed. Such a pressure-sensitive adhesive sheet can be used, for example, for visually recognizing the surface of an adherend through the pressure-sensitive adhesive sheet without impairing the design of the adherend, for example, its appearance and high-grade appearance. In the case where the pressure-sensitive adhesive sheet is in the form of a double-sided pressure-sensitive adhesive sheet having pressure-sensitive adhesive surfaces on both sides, it is preferable that the maximum height Rz of the 1 st pressure-sensitive adhesive surface and the 2 nd pressure-sensitive adhesive surface constituting the double-sided pressure-sensitive adhesive sheet is limited to a predetermined value or less. The double-sided adhesive sheet has high surface smoothness on each adhesive surface, and thus can be bonded without optical distortion or with highly suppressed optical distortion. For example, in the case of an adherend having a transparent member on one side and a design on the other side, the design of the adherend can be visually recognized through the pressure-sensitive adhesive sheet with good visibility.

The maximum height Rz of the pressure-sensitive adhesive surface (including the 1 st pressure-sensitive adhesive surface and the 2 nd pressure-sensitive adhesive surface, unless otherwise specified, the same applies hereinafter) of the pressure-sensitive adhesive sheet is preferably about 600nm or less, more preferably about 500nm or less, still more preferably about 450nm or less, particularly preferably about 400nm or less, and may be less than 350nm, less than 300nm, or less than 250 nm. In some embodiments, the maximum height Rz of the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet may be, for example, about 10nm or more, or about 50nm or more, or about 100nm or more, or about 200nm or more, from the viewpoint of production efficiency and the like. In the embodiment of the psa sheet having the 1 st psa surface and the 2 nd psa surface, the maximum height Rz of the 1 st psa surface and the maximum height Rz of the 2 nd psa surface may be the same level or different levels.

The adhesive surface of the adhesive sheet disclosed herein is preferably limited to a predetermined value or less in arithmetic mean roughness Ra. When the structure including the adhesive surface designed to have a low arithmetic average roughness Ra is used, it is easy to highly suppress optical distortion. In the case where the pressure-sensitive adhesive sheet is in the form of a double-sided pressure-sensitive adhesive sheet having pressure-sensitive adhesive surfaces on both sides, it is preferable that the arithmetic average roughness Ra of the 1 st pressure-sensitive adhesive surface and the 2 nd pressure-sensitive adhesive surface constituting the double-sided pressure-sensitive adhesive sheet is limited to a predetermined value or less. By having high surface smoothness of each pressure-sensitive adhesive surface of the double-sided pressure-sensitive adhesive sheet, it is possible to preferably realize bonding free from optical distortion or highly suppressed in optical distortion.

The arithmetic average roughness Ra of the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet is preferably about 70nm or less, more preferably about 65nm or less, further preferably about 55nm or less, and may be less than 50nm, 45nm or 40 nm. In some embodiments, the arithmetic average roughness Ra of the pressure-sensitive adhesive sheet on the pressure-sensitive adhesive surface may be, for example, about 10nm or more, about 20nm or more, or about 30nm or more (e.g., about 40nm or more), from the viewpoint of production efficiency and the like. In the embodiment of the psa sheet having the 1 st psa surface and the 2 nd psa surface, the arithmetic average roughness Ra of the 1 st psa surface and the arithmetic average roughness Ra of the 2 nd psa surface may be on the same level or different levels.

The maximum height Rz and the arithmetic mean roughness Ra of the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet can be adjusted by the surface properties of the release film laminated on the pressure-sensitive adhesive surface, the peeling force of the release film from the pressure-sensitive adhesive sheet, the thickness of the pressure-sensitive adhesive layer, and the like.

The maximum height Rz of the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet may be the maximum height Rz of the pressure-sensitive adhesive layer surface constituting the pressure-sensitive adhesive sheet. Similarly, the arithmetic average roughness Ra of the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet may be the arithmetic average roughness Ra of the pressure-sensitive adhesive layer surface constituting the pressure-sensitive adhesive sheet. Therefore, the ranges and values of the maximum height Rz and the arithmetic mean roughness Ra of the surface of the pressure-sensitive adhesive layer can be the ranges and values described as the maximum height Rz and the arithmetic mean roughness Ra of the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet.

In addition, the maximum height Rz and arithmetic average roughness Ra of the pressure-sensitive adhesive sheet on the adhesive surface were measured as follows: the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet after the release film was peeled from the pressure-sensitive adhesive sheet with a release film was measured using a noncontact surface roughness measuring apparatus. As the noncontact surface roughness measuring device, a surface roughness measuring device using an optical interference system, for example, a three-dimensional optical profiler (trade name "new view 7300", manufactured by ZYGO) or a product equivalent thereof can be used. The specific measurement operation and the measurement conditions may be set in accordance with the measurement conditions described in the examples below, or in such a manner that results equivalent to or corresponding to the case of the measurement conditions can be obtained.

(Total light transmittance)

In some embodiments, it is suitable that the total light transmittance of the adhesive sheet is, for example, about 50% or more, for example, about 70% or more. In some preferred embodiments, the total light transmittance of the pressure-sensitive adhesive sheet is about 85% or more, more preferably about 90% or more, from the viewpoint of visual recognition through an adherend of the pressure-sensitive adhesive sheet. The upper limit of the total light transmittance is theoretically a value obtained by subtracting the light loss (fresnel loss) due to reflection generated at the air interface from 100%, and may be practically about 95% or less, or about 94% or less (e.g., 93% or less). When the pressure-sensitive adhesive sheet having such a total light transmittance is used, good visibility can be obtained by allowing the pressure-sensitive adhesive sheet to pass through.

(haze value)

In some embodiments, the haze value of the adhesive sheet may be suitably about 10% or less, for example, about 3% or less. In some preferred embodiments, the haze value of the pressure-sensitive adhesive sheet is about 1% or less, more preferably about 0.8% or less, and still more preferably 0.5% or less, from the viewpoint of visual recognition through an adherend of the pressure-sensitive adhesive sheet. The lower limit of the haze value is theoretically 0% and may practically exceed about 0.0%. The "haze value" refers to a ratio of diffuse transmitted light to total transmitted light when visible light is irradiated to a measurement object. Also known as the Haze value. The haze value can be represented by the following formula.

Th[％]＝Td/Tt×100

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

The total light transmittance and haze value of the adhesive sheet can be adjusted by the composition (base polymer type, additive component), thickness, and the like of the adhesive sheet (typically, adhesive layer).

In addition, the total light transmittance of the adhesive sheet may be the total light transmittance of an adhesive layer constituting the adhesive sheet. Similarly, the haze value of the adhesive sheet may be a haze value of an adhesive layer constituting the adhesive sheet. Therefore, as the ranges and values of the total light transmittance and the haze value of the pressure-sensitive adhesive layer, the ranges and values described as the total light transmittance and the haze value of the pressure-sensitive adhesive sheet can be used, respectively.

The total light transmittance and haze value of the pressure-sensitive adhesive sheet can be measured by sticking the pressure-sensitive adhesive sheet to be measured to one surface of a glass plate and measuring the result with a haze meter. As the haze meter, the device name "HM-150N" manufactured by color technology research on village or its equivalent may be used. Specifically, the measurement was carried out by the method described in the examples below.

The pressure-sensitive adhesive sheet having the total light transmittance and haze value as described above may be a colored transparent or colorless transparent pressure-sensitive adhesive sheet. In this specification, "transparent" is used in a concept including translucency. In addition, the optical distortion reducing effect of the adhesive sheet using the technology disclosed herein can be exhibited in a configuration in which at least a part of the adhesive sheet surface has a level of transparency that can be visually recognized through the adhesive sheet, and therefore the adhesive sheet does not need to be transparent or translucent.

(adhesion to glass)

The adhesive strength of the adhesive sheet disclosed herein is not particularly limited, and may be set according to the purpose. In some embodiments, the adhesion of the adhesive sheet to the glass plate (adhesion to glass) is suitably, for example, about 1.0N/20mm or more, and may be about 3.0N/20mm or more (e.g., about 5.0N/20mm or more). From the viewpoint of bonding reliability, the adhesion to glass is preferably about 7.0N/20mm or more, more preferably about 8.0N/20mm or more, further preferably about 9.0N/20mm or more, may be about 10.0N/20mm or more, and may be about 11.0N/20mm or more. The adhesive sheet having the above adhesion to glass can be preferably used for purposes such as joining, fixing, and the like of members. From the viewpoint of easy achievement of balance with other characteristics, the adhesion to glass may be, for example, about 20N/20mm or less, about 16.0N/20mm or less, or about 12.0N/20mm or less. The above adhesion to glass can be adjusted by selecting the composition, thickness, etc. of the adhesive layer.

The adhesion to glass was determined as follows: the adhesive surface to be measured was measured by pressing a 2kg rubber roller against a glass plate while reciprocating once, and peeling the adhesive sheet from the glass plate under conditions of a peeling angle of 180 degrees and a tensile rate of 300 mm/min in accordance with JIS Z0237 using a tensile tester at 23 ℃ and 50% RH, and measuring the peel strength at that time. Specifically, the measurement was carried out by the method described in the examples below.

(modulus of elasticity based on tensile test)

In some preferred embodiments, the elastic modulus (also referred to as initial elastic modulus) of the pressure-sensitive adhesive sheet in the tensile test is 3.0MPa or more. The pressure-sensitive adhesive sheet having a higher elastic modulus tends to exhibit better deformation resistance. The above-described adhesive sheet having a high elastic modulus can be preferably used for purposes such as joining and fixing of members. For example, in the case of a system in which 2 members are joined via an adhesive sheet, the adhesive sheet has high deformation resistance, which contributes to maintaining the relative positions of the two members with high accuracy. In addition, for example, in the case where the film member and another member are joined together via the adhesive sheet, the adhesive sheet has high deformation resistance, which contributes to suppressing occurrence of a change in the appearance of the laminate (press deformation resistance) due to partial pressing from the film member side. In the case where the adherend is a transparent rigid member (e.g., a glass member), it is particularly significant to suppress a change in appearance visually recognized from the adherend side.

In some preferred psa sheets, the elastic modulus may be, for example, 5.0MPa or more, 7.0MPa or more, 10.0MPa or more, 15.0MPa or more, or 20.0MPa or more. The elastic modulus tends to increase and the deformation resistance tends to increase. The upper limit of the above elastic modulus is not particularly limited. The elastic modulus is advantageously 150MPa or less, preferably 120MPa or less, may be 100MPa or less, may be 80MPa or less, or may be 60MPa or less, from the viewpoint of facilitating the balance with other characteristics (for example, 1 or 2 or more characteristics selected from impact resistance, adhesion to glass, haze value, and the like). The elastic modulus based on the tensile test can be adjusted by selection of the composition of the adhesive sheet (typically, the adhesive layer) or the like. The elastic modulus based on the tensile test was determined by the tensile test described above. More specifically, the measurement was carried out by the method described in the examples below.

(impact resistance)

The adhesive sheet disclosed herein preferably has an impact resistance of 2.0J/10mm²The above. When the pressure-sensitive adhesive sheet having high impact resistance is used, a highly reliable bond can be formed. This may be an advantageous feature for adhesive sheets, e.g. for joining, fixing, etc. of components. The pressure-sensitive adhesive sheet can withstand an impact caused by, for example, dropping, collision, or the like, and can satisfactorily maintain the bonding of a member to an adherend.

In some preferred embodiments of the pressure-sensitive adhesive sheet, the impact resistance may be, for example, 2.1J/10mm²Above, 2.3J/10mm²Above, 2.5J/10mm²Above, 2.7J/10mm²Above, 3.0J/10mm²The above. The pressure-sensitive adhesive sheet disclosed herein may have an impact resistance of 3.3J/10mm²Above or 3.5J/10mm²The above manner is preferably implemented. The upper limit of the impact resistance is not particularly limited. From the viewpoint of easy achievement of balance with other characteristics, the impact resistance may be, for example, 20J/10mm²The thickness may be 15J/10mm or less²The thickness may be 10J/10mm or less²The thickness of the film may be 8.0J/10mm or less²The thickness of the film may be 6.0J/10mm or less²The following. Impact resistance can be adjusted by selecting the composition, thickness, etc. of the adhesive layer. Impact resistance is measured by the shear impact test described above. More specifically, the measurement was carried out by the method described in the examples below.

(thickness)

The thickness of the adhesive sheet is appropriately set according to the intended use and the mode of use, and is not limited to a specific range. The thickness of the pressure-sensitive adhesive sheet may be, for example, about 1 μm to 500 μm, and may be, for example, about 3 μm to 500 μm. In some embodiments, the thickness of the pressure-sensitive adhesive sheet is suitably 5 μm or more, and may be, for example, 10 μm or more, preferably 20 μm or more, more preferably 25 μm or more, or may exceed 25 μm. In a thick pressure-sensitive adhesive sheet, optical distortion is easily reduced by the stress dispersion capability of the pressure-sensitive adhesive layer. In addition, a thick adhesive sheet tends to have excellent level difference following properties, and is likely to absorb deformation due to foreign matter or the like. Impact resistance tends to be improved. The technique disclosed herein can be preferably implemented in such a manner that the thickness of the adhesive sheet is 30 μm or more. The thickness of the pressure-sensitive adhesive sheet may be 35 μm or more, may be 40 μm or more, may be 45 μm or more, may be 50 μm or more, may be 75 μm or more, and may be 90 μm or more. On the other hand, when the thickness of the adhesive sheet is increased, the optical path through the adhesive sheet is also increased, and thus optical distortion becomes easily visible. Therefore, in some embodiments, the thickness of the pressure-sensitive adhesive sheet is suitably 200 μm or less, for example, 150 μm or less, 120 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, or 35 μm or less.

< adhesive layer >

In the technique disclosed herein, the type of the adhesive constituting the adhesive layer included in the adhesive sheet is not particularly limited. The pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer containing 1 or 2 or more kinds of pressure-sensitive adhesives selected from known various pressure-sensitive adhesives such as acrylic pressure-sensitive adhesives, rubber pressure-sensitive adhesives (natural rubber-based, synthetic rubber-based, and mixed systems thereof), silicone pressure-sensitive adhesives, polyester pressure-sensitive adhesives, urethane pressure-sensitive adhesives, polyether pressure-sensitive adhesives, polyamide pressure-sensitive adhesives, and fluorine pressure-sensitive adhesives. Here, the acrylic adhesive is an adhesive containing an acrylic polymer as a base polymer (a main component of the polymer component, that is, a component having a content of more than 50% by weight). The same applies to rubber-based adhesives and other adhesives.

(Polymer (A))

In some embodiments, the pressure-sensitive adhesive layer contains a polymer (a). Examples of the material that can be used as the polymer (a) include polymers that exhibit rubber elasticity at room temperature, such as acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, and fluorine polymers, which are known in the field of adhesives. These can be used alone in 1 or a combination of 2 or more.

From the viewpoint of the adhesive properties such as impact resistance, the weight ratio of the polymer (a) in the entire weight of the pressure-sensitive adhesive layer is preferably 40% by weight or more, preferably 50% by weight or more, more preferably 60% by weight or more, further preferably 70% by weight or more, and may be about 80% by weight or more, or may be about 90% by weight or more, or may be about 97% by weight or more (e.g., about 99% by weight or more). When a binder having a high content of the polymer (a) is used, the transparency tends to be excellent. The weight ratio of the polymer (a) in the entire weight of the pressure-sensitive adhesive layer is typically less than 100% by weight, and is preferably 95% by weight or less, preferably 92% by weight or less, may be 90% by weight or less, and may be 87% by weight or less, from the viewpoint of ease of adjustment of the balance of properties.

A preferable example of the polymer (a) is an acrylic polymer. The adhesive layer in the technology disclosed herein may be an acrylic adhesive layer containing an acrylic polymer as a base polymer (a main component among polymer components, i.e., a component having a content of more than 50% by weight). An acrylic pressure-sensitive adhesive is preferable from the viewpoint of transparency, weather resistance, and the like, and easily realizes viscoelastic characteristics excellent in impact resistance without depending heavily on additives such as a softening agent. The acrylic polymer (hereinafter, sometimes referred to as "acrylic polymer (a)") as the polymer (a) is preferably an acrylic polymer composed of a monomer component containing 40% by weight or more of an alkyl (meth) acrylate having a linear or branched alkyl group having 1 to 20 carbon atoms at an ester end. Hereinafter, an alkyl (meth) acrylate having an alkyl group having not less than X and not more than Y carbon atoms at the ester end may be referred to as "(meth) acrylic acid C_X-YAlkyl ester ".

In some embodiments, (meth) acrylic acid C is contained in the entire monomer components of the acrylic polymer (A) from the viewpoint of easy balance of the properties_1-20The proportion of the alkyl ester is preferably more than 40% by weight, and may be, for example, 45% by weight or more, 50% by weight or more, 55% by weight or more, or 60% by weight or more. (meth) acrylic acid C among monomer components_1-20The proportion of the alkyl ester may be 100% by weight, but is preferably 98% by weight or less, for example, 95% by weight or less, or 90% by weight or less, from the viewpoint of easy balance of properties. In some embodiments, (meth) acrylic acid C is contained in the entire monomer component of the acrylic polymer (a) from the viewpoint of improving the cohesive property of the pressure-sensitive adhesive layer_1-20The proportion of the alkyl ester may be 85 wt% or less, 80 wt% or less, 75 wt% or less, 70 wt% or less, 65 wt% or less, or 60 wt% or less, for example.

As (methyl)) Acrylic acid C_1-20Non-limiting specific examples of the alkyl ester 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, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, dodecyl (meth) acrylate, and the like, Tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, and the like.

Among them, it is preferable to use at least (meth) acrylic acid C_4-20Alkyl esters, more preferably at least (meth) acrylic acid C_4-18An alkyl ester. (meth) acrylic acid C is particularly preferred_4-18As the alkyl ester, n-Butyl Acrylate (BA) and 2-ethylhexyl acrylate (2EHA) are listed. (meth) acrylic acid C which can be preferably used_4-20Other specific examples of the alkyl ester include isononyl acrylate, n-Butyl Methacrylate (BMA), 2-ethylhexyl methacrylate (2EHMA), isostearyl acrylate (iSTA) and the like. These (meth) acrylic acids C_4-20The alkyl ester may be used alone in 1 kind or in combination of 2 or more kinds.

The above monomer component preferably contains, for example, at least one or both of n-Butyl Acrylate (BA) and 2-ethylhexyl acrylate (2 EHA). In some embodiments, the monomer component preferably contains at least BA. Here, examples of the monomer component containing at least BA include: a monomeric component of a composition that includes BA and does not include 2EHA, a monomeric component of a composition that includes BA and 2EHA and has a content of 2EHA that is less than a content of BA (e.g., a content of 2EHA that is less than 0.5 times or less than 0.3 times the content of BA).

In some embodiments, the monomer component constituting the acrylic polymer (a) may contain (meth) acrylic acid C in a proportion of 40% by weight or more_4-18An alkyl ester. (meth) acrylic acid C in monomer component_4-18The proportion of the alkyl ester may be, for example, 50% by weight or more, 60% by weight or more, or 65% by weight or more.

In addition, from the viewpoint of improving the cohesive property of the pressure-sensitive adhesive layer, (meth) acrylic acid C in the monomer component_4-18The proportion of the alkyl ester is preferably 99.5% by weight or less, and may be 95% by weight or less, 85% by weight or less, or 75% by weight or less.

The monomer component constituting the acrylic polymer (a) may contain, together with the alkyl (meth) acrylate, if necessary, another monomer (copolymerizable monomer) copolymerizable with the alkyl (meth) acrylate. As the copolymerizable monomer, a monomer having a polar group (for example, a carboxyl group, a hydroxyl group, a nitrogen atom-containing ring, etc.) or a monomer having a relatively high glass transition temperature (for example, 10 ℃ or higher) of a homopolymer can be suitably used. The monomer having a polar group may contribute to introduction of a crosslinking point to the acrylic polymer (a) or increase the cohesive force of the adhesive. The copolymerizable monomer may be used alone in 1 kind or in combination of 2 or more kinds.

Specific non-limiting examples of the copolymerizable monomer include the following monomers.

Carboxyl group-containing monomer: for example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and the like.

Acid anhydride group-containing monomer: for example maleic anhydride, itaconic anhydride.

Hydroxyl group-containing monomer: for example, hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and (4-hydroxymethylcyclohexyl) methyl (meth) acrylate.

Sulfonic acid group-or phosphoric acid group-containing monomer: for example, styrenesulfonic acid, allylsulfonic acid, sodium vinylsulfonate, 2- (meth) acrylamido-2-methylpropanesulfonic acid, (meth) acrylamidopropanesulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalenesulfonic acid, 2-hydroxyethylacryloyl phosphate, and the like.

Epoxy group-containing monomer: examples of the epoxy group-containing acrylate include glycidyl (meth) acrylate, 2-ethyl glycidyl (meth) acrylate, allyl glycidyl ether, and glycidyl (meth) acrylate.

A cyano group-containing monomer: for example, acrylonitrile, methacrylonitrile, and the like.

Isocyanate group-containing monomer: for example, 2-isocyanatoethyl (meth) acrylate and the like.

Amide group-containing monomer: such as (meth) acrylamide; n, N-dialkyl (meth) acrylamides such as N, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N-dipropyl (meth) acrylamide, N-diisopropyl (meth) acrylamide, N-di-N-butyl (meth) acrylamide, and N, N-di-t-butyl (meth) acrylamide; n-alkyl (meth) acrylamides such as N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, and N-N-butyl (meth) acrylamide; n-vinylcarboxylic acid amides such as N-vinylacetamide; a monomer having a hydroxyl group and an amide group, for example, N-hydroxyalkyl (meth) acrylamides such as N- (2-hydroxyethyl) (meth) acrylamide, N- (2-hydroxypropyl) (meth) acrylamide, N- (1-hydroxypropyl) (meth) acrylamide, N- (3-hydroxypropyl) (meth) acrylamide, N- (2-hydroxybutyl) (meth) acrylamide, N- (3-hydroxybutyl) (meth) acrylamide, and N- (4-hydroxybutyl) (meth) acrylamide; monomers having an alkoxy group and an amide group, for example, N-alkoxyalkyl (meth) acrylamides such as N-methoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, and N-butoxymethyl (meth) acrylamide; further, N-dimethylaminopropyl (meth) acrylamide, N- (meth) acryloylmorpholine and the like.

Amino group-containing monomers: for example, aminoethyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylate, tert-butylaminoethyl (meth) acrylate.

Monomer having epoxy group: such as glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, allyl glycidyl ether.

Monomer having nitrogen atom-containing ring: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N- (meth) acryloyl-2-pyrrolidone, N- (meth) acryloylpiperidine, N- (meth) acryloylpyrrolidine, N-vinylmorpholine, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1, 3-oxazin-2-one, N-vinyl-3, 5-morpholinodione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, N-vinylisothiazole, N-vinylpyridazine, etc. (e.g., lactams such as N-vinyl-2-caprolactam).

Monomer having succinimide skeleton: for example, N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyhexamethylene succinimide, and the like.

Maleimide group: for example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide and the like.

Itaconimides: for example, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-lauryl itaconimide, etc.

Aminoalkyl (meth) acrylates: for example, aminoethyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylate, N-diethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate.

Alkoxy group-containing monomers: alkoxyalkyl (meth) acrylates (alkoxyalkyl (meth) acrylates) such as 2-methoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, and ethoxypropyl (meth) acrylate; alkoxyalkylene glycol (meth) acrylates (for example, alkoxypolyalkylene glycol (meth) acrylates) such as methoxyethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, and methoxypolypropylene glycol (meth) acrylate.

Alkoxysilyl group-containing monomer: for example, alkoxysilyl group-containing (meth) acrylates such as 3- (meth) acryloyloxypropyltrimethoxysilane, 3- (meth) acryloyloxypropyltriethoxysilane, 3- (meth) acryloyloxypropylmethyldimethoxysilane and 3- (meth) acryloyloxypropylmethyldiethoxysilane, and alkoxysilyl group-containing vinyl compounds such as vinyltrimethoxysilane and vinyltriethoxysilane.

Vinyl esters: for example, vinyl acetate, vinyl propionate, and the like.

Vinyl ethers: for example, vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether.

Aromatic vinyl compound: for example, styrene, alpha-methylstyrene, vinyltoluene, and the like.

Olefins: for example, ethylene, butadiene, isoprene, isobutylene, and the like.

(meth) acrylate having alicyclic hydrocarbon group: examples of the (meth) acrylic acid ester include alicyclic hydrocarbon group-containing (meth) acrylic acid esters such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and adamantyl (meth) acrylate.

(meth) acrylate having an aromatic hydrocarbon group: for example, aromatic hydrocarbon group-containing (meth) acrylates such as phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, and benzyl (meth) acrylate.

And heterocyclic ring-containing (meth) acrylates such as tetrahydrofurfuryl (meth) acrylate, halogen atom-containing (meth) acrylates such as vinyl chloride-and fluorine atom-containing (meth) acrylates, silicon atom-containing (meth) acrylates such as silicone (meth) acrylates, and (meth) acrylates derived from alcohols derived from terpene compounds.

When such a copolymerizable monomer is used, the amount thereof is not particularly limited, and is preferably 0.01% by weight or more of the entire monomer components. From the viewpoint of more effectively exhibiting the effect of using the copolymerizable monomer, the amount of the copolymerizable monomer to be used may be 0.1% by weight or more, or may be 0.5% by weight or more of the entire monomer components. From the viewpoint of easily obtaining the balance of the adhesive properties, the amount of the copolymerizable monomer to be used is preferably 50% by weight or less, more preferably 40% by weight or less, of the entire monomer components.

In some embodiments, the monomer component constituting the acrylic polymer (a) may contain a monomer having a nitrogen atom. By using a monomer having a nitrogen atom, the cohesive force of the adhesive can be increased, and preferably the peel strength after photocuring is improved. As a preferred example of the monomer having a nitrogen atom, a monomer having a ring containing a nitrogen atom is mentioned. As the monomer having a nitrogen atom-containing ring, the above-exemplified monomers and the like can be used, and for example, an N-vinyl cyclic amide represented by the general formula (1) can be used.

Here, in the general formula (1), R¹Is an organic radical having a valence of 2, in particular- (CH)₂)_n-. n is an integer of 2 to 7 (preferably 2,3 or 4). Among them, N-vinyl-2-pyrrolidone can be preferably used. Other preferable examples of the monomer having a nitrogen atom include (meth) acrylamide.

The amount of the monomer having a nitrogen atom (preferably, a monomer having a ring containing a nitrogen atom) to be used is not particularly limited, and may be, for example, 1% by weight or more, 3% by weight or more, and further 5% by weight or more, or 7% by weight or more of the entire monomer components. In some embodiments, the amount of the monomer having a nitrogen atom may be 10% by weight or more, 15% by weight or more, or 20% by weight or more of the entire monomer components. The amount of the monomer having a nitrogen atom to be used is, for example, preferably 40% by weight or less, and may be 35% by weight or less, 30% by weight or less, or 25% by weight or less of the entire monomer component. In some other embodiments, the amount of the monomer having a nitrogen atom to be used may be, for example, 20 wt% or less, or 15 wt% or less of the entire monomer component.

In some embodiments, the monomer component constituting the acrylic polymer (a) may contain a hydroxyl group-containing monomer. By using the hydroxyl group-containing monomer, the cohesive force of the adhesive, the degree of crosslinking (e.g., crosslinking based on an isocyanate crosslinking agent) can be adjusted as appropriate. The amount of the hydroxyl group-containing monomer used is not particularly limited, and may be, for example, 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 whole monomer component. In some embodiments, the amount of the hydroxyl group-containing monomer used is, for example, suitably 40% by weight or less, and may be 30% by weight or less, 25% by weight or less, or 20% by weight or less of the entire monomer components, from the viewpoint of suppressing the water absorption of the pressure-sensitive adhesive layer. In some other embodiments, the amount of the hydroxyl group-containing monomer used may be, for example, 15 wt% or less, 10 wt% or less, or 5 wt% or less of the entire monomer component.

In some embodiments, the ratio of the carboxyl group-containing monomer in the monomer component of the acrylic polymer (a) may be, for example, 2 wt% or less, 1 wt% or less, or 0.5 wt% or less (for example, less than 0.1 wt%). The monomer component of the acrylic polymer (a) may be substantially free of a carboxyl group-containing monomer. Herein, the substantial absence of the carboxyl group-containing monomer means that at least the carboxyl group-containing monomer is not intentionally used. The adhesive layer containing the acrylic polymer (a) in which the amount of the carboxyl group-containing monomer is limited as described above is preferable from the viewpoint of preventing metal corrosion. The pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer can also be preferably used in a mode in which the pressure-sensitive adhesive layer is brought into contact with an adherend having a metal material, for example.

In some 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 improves the peel strength after photocuring. The (meth) acrylate containing an alicyclic hydrocarbon group exemplified above can be used, and for example, cyclohexyl acrylate and isobornyl acrylate can be preferably used. The amount of the alicyclic hydrocarbon group-containing (meth) acrylate to be used is not particularly limited, and may be, for example, 1% by weight or more, 3% by weight or more, or 5% by weight or more of the whole monomer components. In some embodiments, the amount of the alicyclic hydrocarbon group-containing (meth) acrylate used may be 10% by weight or more, or 15% by weight or more of the entire monomer components. The upper limit of the amount of the alicyclic hydrocarbon group-containing (meth) acrylate to be used is preferably about 40% by weight or less, and may be, for example, 30% by weight or less, or may be 25% by weight or less (for example, 15% by weight or less, or further 10% by weight or less).

The polymerization method for forming (synthesizing) the polymer (a) from the monomer components is not particularly limited, and various conventionally known polymerization methods can be suitably used. For example, thermal polymerization such as solution polymerization, emulsion polymerization, and bulk polymerization (typically, in the presence of a thermal polymerization initiator); photopolymerization by irradiation with light such as ultraviolet rays (typically in the presence of a photopolymerization initiator); a polymerization method such as radiation polymerization by irradiation with radiation such as β -rays and γ -rays. It is also possible to carry out the polymerization in combination with 2 or more polymerization methods (e.g., stepwise).

As the solvent (polymerization solvent) for the solution polymerization, for example, aromatic compounds (typically aromatic hydrocarbons) selected from toluene and the like; esters such as ethyl acetate and butyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; halogenated alkanes such as 1, 2-dichloroethane; lower alcohols (e.g., monohydric alcohols having 1 to 4 carbon atoms) such as isopropyl alcohol; ethers such as t-butyl methyl ether; any one solvent or a mixed solvent of 2 or more kinds of ketones such as methyl ethyl ketone.

In the polymerization, a known or customary thermal polymerization initiator or photopolymerization initiator can be used depending on the polymerization method, polymerization system, and the like. Such polymerization initiators may be used in 1 kind alone or in appropriate combinations of 2 or more kinds.

The thermal polymerization initiator is not particularly limited, but for example, an azo polymerization initiator, a peroxide initiator, a redox initiator obtained by combining a peroxide and a reducing agent, a substituted ethylene initiator, and the like can be used. More specifically, examples of the azo initiator include 2,2 ' -Azobisisobutyronitrile (AIBN), 2 ' -azobis (2-methylpropionamidine) disulfate, 2 ' -azobis (2-amidinopropane) dihydrochloride, 2 ' -azobis [2- (5-methyl-2-imidazolin-2-yl) propane ] dihydrochloride, 2 ' -azobis (N, N ' -dimethyleneisobutylamidine), and 2,2 ' -azobis [ N- (2-carboxyethyl) -2-methylpropionamidine ] hydrate; persulfates such as potassium persulfate and ammonium persulfate; peroxide initiators such as benzoyl peroxide, t-butyl hydroperoxide and hydrogen peroxide; substituted ethane-based initiators such as phenyl-substituted ethane; examples of the redox initiator include, but are not limited to, a combination of a persulfate and sodium bisulfite and a combination of a peroxide and sodium ascorbate. The thermal polymerization can be preferably carried out at a temperature of, for example, about 20 to 100 ℃ (typically about 40 to 80 ℃), but is not limited thereto.

The photopolymerization initiator is not particularly limited, and examples thereof include ketal photopolymerization initiators, acetophenone photopolymerization initiators, benzoin ether photopolymerization initiators, acylphosphine oxide photopolymerization initiators, α -ketol photopolymerization initiators, aromatic sulfonyl chloride photopolymerization initiators, photoactive oxime photopolymerization initiators, benzoin photopolymerization initiators, benzil photopolymerization initiators, benzophenone photopolymerization initiators, and thioxanthone photopolymerization initiators.

The amount of the polymerization initiator to be used is not particularly limited, and may be any amount generally used in accordance with the polymerization method, polymerization system, etc. For example, the polymerization initiator may be used in an amount of about 0.001 to 5 parts by weight (typically about 0.01 to 2 parts by weight, for example about 0.01 to 1 part by weight) based on 100 parts by weight of the monomer to be polymerized.

In the above polymerization, various conventionally known chain transfer agents (also understood as a molecular weight regulator or a polymerization degree regulator) may be used as necessary. As the chain transfer agent, mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, thioglycolic acid and α -thioglycerol can be used. Alternatively, a chain transfer agent containing no sulfur atom (non-sulfur chain transfer agent) may be used. Specific examples of the non-sulfur chain transfer agent include anilines such as N, N-dimethylaniline and N, N-diethylaniline; terpenes such as α -pinene and terpinolene; styrenes such as α -methylstyrene and α -methylstyrene dimer; compounds having benzylidene group such as dibenzylidene acetone, cinnamyl alcohol and cinnamyl aldehyde; hydroquinones such as hydroquinone and naphthalenediol; quinones such as benzoquinone and naphthoquinone; olefins such as 2, 3-dimethyl-2-butene and 1, 5-cyclooctadiene; alcohols such as phenol, benzyl alcohol, and allyl alcohol; and benzyl hydrides such as diphenylbenzene and triphenylbenzene. The chain transfer agent may be used alone in 1 kind or in combination of 2 or more kinds. It should be noted that the technique disclosed herein can also be preferably carried out without using a chain transfer agent.

The amount of the chain transfer agent used may be, for example, about 0.005 to 1 part by weight based on 100 parts by weight of the monomer component. In some embodiments, the amount of the chain transfer agent used may 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, relative to 100 parts by weight of the monomer component, from the viewpoint of impact resistance. In some embodiments, the amount of the chain transfer agent used may be, for example, 0.5 parts by weight or less, 0.2 parts by weight or less, 0.1 parts by weight or less, or less than 0.1 parts by weight (for example, 0.09 parts by weight or less) relative to 100 parts by weight of the monomer component, from the viewpoint of the deformation resistance.

In the technique disclosed herein, the glass transition temperature (Tg) of the polymer (A) is not particularly limited, but is suitably less than 0 ℃ and preferably less than-10 ℃ and preferably less than-20 ℃. By lowering the Tg of the polymer (A), the impact resistance tends to be improved. In several ways, the Tg of the polymer (A) may be less than-25 ℃ or less than-30 ℃. The Tg of the polymer (A) is typically-80 ℃ or higher, and may be, for example, -70 ℃ or higher, may be-60 ℃ or higher, or may be-55 ℃ or higher. From the viewpoint of improving the above elastic modulus, the Tg of the polymer (A) may be, in some embodiments, preferably-50 ℃ or higher, more preferably-45 ℃ or higher, may be-40 ℃ or higher, may be-38 ℃ or higher, or may be-35 ℃ or higher.

Herein, the Tg of a polymer in the present specification means the Tg obtained by the Fox equation based on the composition of the monomer component used for the preparation of the polymer. The above Fox formula is a relational expression between Tg of a copolymer and glass transition temperature Tgi of a homopolymer obtained by homopolymerizing monomers constituting the copolymer, as shown below.

1/Tg＝Σ(Wi/Tgi)

In the above Fox formula, Tg represents the glass transition temperature (unit: K) of the copolymer, Wi represents the weight fraction (copolymerization ratio on a weight basis) of the monomer i in the copolymer, and Tgi represents the glass transition temperature (unit: K) of the homopolymer of the monomer i. When the polymer to be subjected to determination of Tg is a homopolymer, Tg of the homopolymer coincides with Tg of the polymer to be subjected.

The glass transition temperature of the homopolymer used for calculation of Tg was the value described in the publicly known data. For example, the following values are used for the glass transition temperatures of the homopolymers of the monomers listed below.

For the glass transition temperature of the homopolymer of the monomer other than the above examples, the value described in "Polymer Handbook" (3 rd edition, John Wiley & Sons, Inc.,1989) was used. When a plurality of values are described in this document, the highest value is used.

The weight average molecular weight (Mw) of the polymer (a) is not particularly limited. In some embodiments, the Mw of the polymer (A) is, for example, about 10X 10 from the viewpoint of achieving a more balanced combination of the deformation resistance and the impact resistance⁴The above is appropriate, preferably more than 20X 10⁴May exceed 30X 10⁴Or more than 40X 10⁴Or more than 50X 10⁴. Further, the upper limit of Mw of the polymer (A) may be about 500X 10⁴The following. In some embodiments, the Mw of the polymer (a) may be, for example, 300 × 10 from the viewpoint of adhesion to an adherend and peel strength⁴Hereinafter, the number may be 150 × 10⁴Hereinafter, the number of layers may be 100 × 10⁴Hereinafter, the value may be 90 × 10⁴Hereinafter, the value may be 75 × 10⁴The following.

The above-described examples of Mw are also applicable to Mw of the polymer (a) in the adhesive layer of the adhesive sheet disclosed herein, and also to Mw of the polymer (a) in the adhesive composition used for formation of the adhesive layer.

The Mw is a value obtained by Gel Permeation Chromatography (GPC) in terms of standard polystyrene. As the GPC apparatus, for example, the model name "HLC-8220 GPC" (manufactured by Tosoh corporation) or its equivalent can be used. As the measurement conditions of GPC, for example, the following method can be employed. Mw in the examples described below was measured by the following method.

(GPC measurement conditions)

The device comprises the following steps: HLC-8220GPC, manufactured by Tosoh corporation

Column:

a sample column; TSKguardcolumn Super HZ-H (1 root) + TSKgel Super HZM-H (2 roots) manufactured by Tosoh corporation

A reference column; TSKgel Super H-RC (1 root) manufactured by Tosoh corporation

Flow rate: 0.6mL/min

Injection amount: 10 μ L

Column temperature: 40 deg.C

Eluent: THF (tetrahydrofuran)

Concentration of injected sample: 0.2% by weight

A detector: differential refractometer

The weight average molecular weight was calculated by polystyrene conversion.

(photoreactive monomer (B))

In some preferred embodiments, the adhesive layer may contain a photoreactive monomer (B) in addition to the polymer (a) (e.g., acrylic polymer (a)) as described above. As the photoreactive monomer (B), a compound having 2 or more ethylenically unsaturated groups contained in a molecule (hereinafter also referred to as "functional group number") can be used. The upper limit of the number of functional groups of the compound used as the photoreactive monomer (B) is not particularly limited. The number of the functional groups may be, for example, 50 or less, 40 or less, 30 or less, 20 or less, or 15 or less. In some embodiments, a compound having an ethylenically unsaturated group with a functional group number of, for example, 2 to 10, preferably 2 to 8, and more preferably 2 to 6, may be used. The photoreactive monomer (B) may be used alone in 1 kind or in combination of 2 or more kinds.

The photoreactive monomer (B) contained in the pressure-sensitive adhesive layer may be bonded to an adherend and then the ethylenically unsaturated group may be reacted by irradiation with light (e.g., ultraviolet light) or the like to form a crosslinked structure. The pressure-sensitive adhesive sheet containing the photoreactive monomer (B) in the pressure-sensitive adhesive layer is cured by ultraviolet irradiation or the like after being attached to an adherend, thereby improving the deformation resistance of the pressure-sensitive adhesive layer. This makes it possible to suitably combine good conformability to the surface shape of an adherend when the adherend is adhered to the adherend and high deformation resistance after adhesion.

Examples of the above ethylenically unsaturated group include, but are not limited to, acryloyl, methacryloyl, vinyl and allyl groups. The photoreactive monomer (B) may have 2 or more ethylenically unsaturated groups in the molecule, which are the same as each other, or may have 2 or more different groups. Preferred ethylenically unsaturated groups from the viewpoint of photoreactivity include acryloyl and methacryloyl groups. Among them, acryloyl is preferable.

The functional group equivalent of the compound used as the photoreactive monomer (B) is not particularly limited. The functional group equivalent may be, for example, about 50 to 10000g/mol, about 50 to 8000g/mol, about 50 to 5000g/mol, about 50 to 3000g/mol, or about 50 to 2000 g/mol. In some embodiments, the photoreactive monomer (B) is preferably a compound having a functional group equivalent of about 60 to 800g/mol (more preferably about 80 to 600 g/mol) from the viewpoint of photocurability.

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

The molecular weight of the photoreactive monomer (B) is not particularly limited, and may be selected so as to exhibit a desired effect as appropriate. For example, as the photoreactive monomer (B), a monomer having a molecular weight of about 20000 or less can be used. In some embodiments, the molecular weight of the photoreactive monomer (B) may be, for example, 16000 or less, 10000 or less, 4000 or less, 1500 or less, or 1000 or less, from the viewpoint of ease of preparation of the adhesive composition, coatability, and the like. The molecular weight of the photoreactive monomer (B) is, for example, 100 or more, typically 120 or more. In some embodiments, the molecular weight of the photoreactive monomer (B) may be, for example, 150 or more, 200 or more, 280 or more, 350 or more, 420 or more, 480 or more, or 550 or more, from the viewpoint of processability, handleability, and the like of the psa sheet.

In the adhesive sheet disclosed herein, the amount of the photoreactive monomer (B) contained in the adhesive layer is not particularly limited, and may be appropriately set according to the target performance (for example, the elastic modulus of the adhesive layer after photocuring). In some embodiments in which the adhesive layer contains the polymer (a) and the photoreactive monomer (B), the amount of the photoreactive monomer (B) may be, for example, 1 part by weight or more and 3 parts by weight or more per 100 parts by weight of the polymer (a) contained in the adhesive layer. From the viewpoint of easily improving the elastic modulus of the pressure-sensitive adhesive layer after photocuring, the amount of the photoreactive monomer (B) may be 5 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, or 20 parts by weight or more, relative to 100 parts by weight of the polymer (a). From the viewpoint of the cohesive property of the pressure-sensitive adhesive layer before photocuring and the handling property (e.g., processability) of the pressure-sensitive adhesive sheet, the amount of the photoreactive monomer (B) is preferably 80 parts by weight or less, more preferably 60 parts by weight or less, and may be 50 parts by weight or less, and may be 40 parts by weight or less, and may be 35 parts by weight or less, based on 100 parts by weight of the polymer (a).

In some embodiments, the adhesive layer preferably contains at least a compound B1 having a ring structure and 2 or more ethylenically unsaturated groups in a molecule as the photoreactive monomer (B). When the adhesive layer containing the compound B1 having such a structure is used, the deformation resistance of the adhesive layer can be effectively improved by light irradiation. The ring in the above ring structure may be an aliphatic ring or an aromatic ring. The ring may be a carbocyclic ring or a heterocyclic ring. The number of rings contained in one molecule of compound B1 may be 1, or 2 or more. The upper limit of the number of rings contained in the compound B1 is not particularly limited, and may be, for example, 100 or less, 70 or less, 50 or less, 30 or less, 15 or less, 8 or less, 6 or less, 5 or less, or 4 or less. When the compound B1 contains 2 or more rings, these rings may or may not form a fused ring (typically, a bicyclic or tricyclic fused ring) formed by 2 or more rings. The above-mentioned ring is preferably contained in the main chain of compound B1. That is, it is preferable that one ethylenically unsaturated group of the compound B1 and at least one other ethylenically unsaturated group are linked via the above-mentioned ring structure. The compound B1 may be used alone in 1 kind or in combination of 2 or more kinds.

As the compound B1, a compound having a cyclic structure and 2 or more ethylenically unsaturated groups in the molecule and having a functional group equivalent of 100g/mol or more can be preferably used. When a pressure-sensitive adhesive sheet containing the compound B1 satisfying the functional group equivalent in the pressure-sensitive adhesive layer is used, the pressure-sensitive adhesive sheet has high deformation resistance and can suitably form a joint having high impact resistance. Although the reason why such an effect is obtained is not particularly limited, it is considered that the compound B1 can effectively increase the elastic modulus of the pressure-sensitive adhesive layer after light irradiation by the rigidity of the ring structure to impart deformation resistance, and the compound B1 has a predetermined or more equivalent functional group, so that a crosslinked structure having high resistance to impact can be formed while maintaining the distance between crosslinking points. In some embodiments, the functional group equivalent of compound B1 may be, for example, 120g/mol or more, or may be 150g/mol or more, or may be 180g/mol or more, or may be 230g/mol or more, or may be 280g/mol or more, or may be 320g/mol or more, or may be 350g/mol or more. The increase in the functional group equivalent of the compound B1 tends to improve the impact resistance. The functional group equivalent of the compound B1 may be, for example, 10000g/mol or less, 8000g/mol or less, 5000g/mol or less, 3000g/mol or less, or 2000g/mol or less. In some embodiments, the functional group equivalent of the compound B1 is preferably 800g/mol or less, more preferably 600g/mol or less, from the viewpoint of photocurability and the like. In some embodiments, the functional group equivalent of compound B1 may be 500g/mol or less, or 400g/mol or less, or 300g/mol or less.

In some embodiments, the number of functional groups of the compound B1 may be, for example, 2 to 50, 2 to 40, 2 to 30, 2 to 10, for example, 2 to 6, 2 to 4, or 2 to 3. Among the several ways, compound B1 having a functional group number of 2 can be preferably used.

The compounds B1 may also have functional groups other than ethylenically unsaturated groups. Examples of the functional group other than the ethylenically unsaturated group include a hydroxyl group, a carboxyl group, and an amino group. Preferred examples of the functional group other than the ethylenically unsaturated group include a hydroxyl group and an amino group.

Examples of the compound B1 include bisphenol a type epoxy (meth) acrylates such as bisphenol a glycidyl ether (meth) acrylic acid adducts, bisphenol a glycidyl amine (meth) acrylic acid adducts, bisphenol a glycidyl ester (meth) acrylic acid adducts, and the like; alkylene oxide-modified bisphenol a (meth) acrylates such as Ethylene Oxide (EO) -modified bisphenol a di (meth) acrylate and Propylene Oxide (PO) -modified bisphenol a di (meth) acrylate; bisphenol F type epoxy (meth) acrylates such as bisphenol F glycidyl ether (meth) acrylic acid adducts, bisphenol F glycidyl amine (meth) acrylic acid adducts, bisphenol F glycidyl ester (meth) acrylic acid adducts, and the like; alkylene oxide-modified bisphenol F (meth) acrylates such as EO-modified bisphenol F di (meth) acrylate and PO-modified bisphenol F di (meth) acrylate; bisphenol E type epoxy (meth) acrylates such as bisphenol E glycidyl ether (meth) acrylic acid adducts, bisphenol E glycidyl amine (meth) acrylic acid adducts, bisphenol E glycidyl ester (meth) acrylic acid adducts, and the like; alkylene oxide-modified bisphenol E (meth) acrylates such as EO-modified bisphenol E di (meth) acrylate and PO-modified bisphenol E di (meth) acrylate; (meth) acrylates having a fluorene skeleton such as 9, 9-bis (4-hydroxyphenyl) fluorene di (meth) acrylate and 9, 9-bis [4- (2-hydroxyethoxy) phenyl ] fluorene di (meth) acrylate; (meth) acrylates having an aliphatic ring (which may be an alicyclic fused ring.) such as tricyclodecane dimethanol di (meth) acrylate, hydrogenated bisphenol a type epoxy (meth) acrylate, hydrogenated bisphenol F type epoxy (meth) acrylate, hydrogenated bisphenol E type epoxy (meth) acrylate, hydrogenated phthalic acid type epoxy (meth) acrylate, hydrogenated terpene phenol (meth) acrylate, 1, 4-cyclohexanedimethanol diglycidyl ether (meth) acrylate, and the like; (meth) acrylic acid adducts of novolak-type epoxy resins; (meth) acrylic acid adducts of thioether type epoxy resins; (meth) acrylic acid adducts of naphthalene type epoxy resins; (meth) acrylic acid adducts of dicyclopentadiene type epoxy resins; (meth) acrylic acid adducts of alkyldiphenol type epoxy resins; (meth) acrylic acid adducts of biphenyl type epoxy resins; (meth) acrylic acid adducts of terpene phenol resins; isocyanurate type (meth) acrylates such as tris (2-hydroxyethyl) isocyanurate di (meth) acrylate and tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate; divinylbenzene; hydroquinone di (meth) acrylate; resorcinol di (meth) acrylate; modified products of any of the above materials (for example, amine-modified products, acid-modified products, and halogen-modified products) and the like, but are not limited thereto. Among several ways, it may be preferable to use the compound B1 having an aromatic carbocyclic ring. Preferred examples of the compound B1 include compounds having a bisphenol a structure such as bisphenol a-type epoxy (meth) acrylate, alkylene oxide-modified bisphenol a (meth) acrylate, and modified products thereof (e.g., amine-modified products).

Examples of commercially available products that can be used as compound B1 include, but are not limited to, the trade names "A-DCP", "A-BPE-4" available from Ningzhou chemical industries, the trade names "Viscoat # 540", "Viscoat #700 HV", the trade names "R-114F" available from Nippon chemical Co., Ltd, the trade names "Epoxy Ester 3000A", "Epoxy Ester80 MFA" available from Kakko chemical Co., Ltd, the trade names "EBECRYL 3700", "EBECRYL 3703", and "EBECRYL 3603" available from DAICEL-ALLNEX LTD.

The amount of the compound B1 relative to 100 parts by weight of the polymer (a) contained in the pressure-sensitive adhesive layer is not particularly limited, and may be, for example, 0.5 parts by weight or more. In some embodiments, the amount of compound B1 relative to 100 parts by weight of polymer (a) may be, for example, 1 part by weight or more, 3 parts by weight or more, 5 parts by weight or more, 7 parts by weight or more, 10 parts by weight or more, or 15 parts by weight or more, from the viewpoint of easily obtaining a pressure-sensitive adhesive layer having both deformation resistance and impact resistance in a balanced manner. From the viewpoint of the cohesive property of the pressure-sensitive adhesive layer before photocuring and the handling property of the pressure-sensitive adhesive sheet, the amount of the compound B1 is preferably 80 parts by weight or less, more preferably 60 parts by weight or less, and may be 50 parts by weight or less, and may be 40 parts by weight or less, and may be 35 parts by weight or less, and may be 25 parts by weight or less, and may be 15 parts by weight or less, based on 100 parts by weight of the polymer (a).

In some embodiments, the pressure-sensitive adhesive layer may contain, as the photoreactive monomer (B), a compound B2 having a functional group number of 2 or more and no ring structure in a molecule. Compound B2 is preferably used in combination with compound B1. By this, the crosslinked structure of the pressure-sensitive adhesive layer is adjusted, and a joint having both deformation resistance and impact resistance can be formed more suitably. The compound B2 may be used alone in 1 kind or in combination of 2 or more kinds.

The number of functional groups of compound B2 may be, for example, 50 or less, 40 or less, 30 or less, 20 or less, or 15 or less. The number of functional groups of the compound B2 used in the above-mentioned embodiments may be, for example, 2 to 10, preferably 3 to 10, 3 to 8, or 4 to 6. For example, in the embodiment using a compound having a functional group number of 2 as compound B1, it is advantageous to use compound B2 having a functional group number of 3 or more (preferably 4 or more, more preferably 5 or more, and still more preferably 6 or more).

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

Examples of the compound that can be used as compound B2 include, but are not limited to, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, trimethylolethane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, neopentyl glycol di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, EO-modified products and/or PO modified products of any of the above materials, and the like.

In the embodiment using 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 may be, for example, 0.1 part by weight or more. In some embodiments, the amount of compound B2 relative to 100 parts by weight of polymer (a) may be, for example, 1 part by weight or more, 2 parts by weight or more, 4 parts by weight or more, 6 parts by weight or more, 10 parts by weight or more, or 12 parts by weight or more, from the viewpoint of easily obtaining a pressure-sensitive adhesive layer having both deformation resistance and impact resistance in a balanced manner. In some embodiments, the amount of the compound B2 is, for example, 25 parts by weight or less, preferably 17 parts by weight or less, and may be 15 parts by weight or less, 13 parts by weight or less, or 9 parts by weight or less, based on 100 parts by weight of the polymer (a), from the viewpoint of suppressing a decrease in adhesion to an adherend due to excessive crosslinking.

In the embodiment using the compound B1 and the compound B2 in combination, the compound B2 preferably has a functional group number of 3 or more and a functional group equivalent smaller than that of the compound B1 used in combination therewith. In several ways, the functional group equivalent FE of the compound B2₂Functional group equivalent FE relative to Compound B1₁Ratio of (FE)₂/FE₁) For example, it may be 0.9 or less, 0.7 or less, 0.5 or less, or 0.4 or less. In this case, the elastic modulus-improving effect of the photoreactive monomer (B) can be effectively exhibited. The above ratio (FE)₂/FE₁) The lower limit of (B) is not particularly limited, and may be, for example, 0.01 or more, 0.1 or more,The concentration may be 0.2 or more.

In the manner of using the compound B1 in combination with the compound B2, the amount W of the compound B2₂Amount W used relative to Compound B1₁Weight ratio of (W)₂/W₁) There is no particular limitation. In some aspects, the weight ratio (W) is₂/W₁) For example, the amount of the organic solvent may be 0.05 to 10, 0.1 to 5, 0.2 to 3, or 0.3 to 2. By mixing the weight ratio (W)₂/W₁) Within any of the above ranges, the effect of the combined use of compound B1 and compound B2 tends to be exhibited as appropriate.

In some other embodiments using the photoreactive monomer (B) (typically, compound B2), the amount of the photoreactive monomer (B) (typically, compound B2) to be used may be about 3 wt% or less, preferably about 2 wt% or less, and more preferably about 1 wt% or less (e.g., about 0.5 wt% or less) of the monomer components of the polymer (a). The lower limit of the amount of the photoreactive monomer (B) (typically, the compound B2) used is not particularly limited as long as it is more than 0% by weight. The amount of the photoreactive monomer (B) (typically, the compound B2) is preferably about 0.001 wt% or more (e.g., about 0.01 wt% or more) based on the monomer component.

In several ways, the photoreactive monomer (B) may be included in the adhesive layer in a free form. The adhesive layer may be suitably formed using an adhesive composition containing the photoreactive monomer (B) in a free form. The "free form" herein means that the photoreactive monomer (B) is not chemically bonded to the adhesive layer or other components (e.g., the polymer (a)) contained in the adhesive composition. The adhesive composition containing the photoreactive monomer (B) in a free form is advantageous from the viewpoint of ease of preparation and suppression of gelation.

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

(acrylic acid oligomer)

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein may contain an acrylic oligomer from the viewpoints of improving the cohesive strength, improving the adhesiveness to the surface adjacent to the pressure-sensitive adhesive layer (for example, the surface of a support substrate in the pressure-sensitive adhesive sheet, the surface of an adherend to which the pressure-sensitive adhesive sheet is adhered), and the like. The adhesive layer including the acrylic oligomer may be preferably formed using an adhesive composition including the acrylic oligomer. As the acrylic oligomer, a substance having a higher Tg than the Tg of the polymer (a) is preferably used.

The Tg of the acrylic oligomer is not particularly limited, and may be, for example, about 20 ℃ to 300 ℃. The Tg may be, for example, about 30 ℃ or higher, about 40 ℃ or higher, about 60 ℃ or higher, about 80 ℃ or higher, or about 100 ℃ or higher. When the Tg of the acrylic oligomer is high, the effect of improving the cohesive force tends to be generally high. From the viewpoint of anchorage to the support base material, impact absorbability, and the like, the Tg of the acrylic oligomer may be, for example, about 250 ℃ or less, about 200 ℃ or less, about 180 ℃ or less, or about 150 ℃ or less. The Tg of the acrylic oligomer is a value calculated based on the Fox equation, similarly to the Tg of the polymer (a).

The Mw of the acrylic oligomer is not particularly limited, and may be, for example, about 1000 or more, suitably about 1500 or more, about 2000 or more, or about 3000 or more. The Mw of the acrylic oligomer may be, for example, suitably less than about 30000 and less than about 10000, or may be less than about 7000 and less than about 5000. When Mw is within the above range, the effect of improving the cohesive property of the pressure-sensitive adhesive layer and the adhesiveness to the adjacent surface can be easily and suitably exhibited. The Mw of the acrylic oligomer can be determined as a value in terms of standard polystyrene by GPC measurement. Specifically, for example, the measurement can be performed by using TSKgelGMH-H (20). times.2 columns in HPLC8020 manufactured by Tosoh corporation, and tetrahydrofuran solvent at a flow rate of about 0.5 mL/min.

Examples of the monomer component constituting the acrylic oligomer include the various (meth) acrylic acids C_1-20An alkyl ester; the above-mentioned various alicyclic hydrocarbon group-containing (meth) acrylates; the above various aromatic hydrocarbon group-containing (meth) acrylates; a (meth) acrylate monomer such as a (meth) acrylate derived from an alcohol derived from a terpene compound. These can be used alone in 1 or a combination of 2 or more.

From the viewpoint of improving adhesiveness, it is preferable that the acrylic oligomer contains, as a monomer unit, an acrylic monomer having a bulky structure represented by an alkyl (meth) acrylate having a branched structure in an alkyl group such as isobutyl (meth) acrylate or tert-butyl (meth) acrylate, a (meth) acrylate having an alicyclic hydrocarbon group, a (meth) acrylate having an aromatic hydrocarbon group, or the like. In addition, in the case of using ultraviolet light during the synthesis of the acrylic oligomer or the production of the pressure-sensitive adhesive layer, a monomer having a saturated hydrocarbon group at the ester end is preferable from the viewpoint that inhibition of polymerization is not likely to occur, and for example, an alkyl (meth) acrylate having an alkyl group with a branched structure or a (meth) acrylate containing a saturated alicyclic hydrocarbon group can be suitably used.

The proportion of the (meth) acrylate monomer in the total monomer components constituting the acrylic oligomer is typically more than 50% by weight, preferably 60% by weight or more, and more preferably 70% by weight or more (for example, 80% by weight or more, and further 90% by weight or more). In some preferred embodiments, the acrylic oligomer has a monomer composition consisting essentially of only 1 or 2 or more (meth) acrylate monomers. The monomer component comprises a (meth) acrylate containing an alicyclic hydrocarbon group and a (meth) acrylic acid C_1-20In the case of the alkyl ester, the weight ratio thereof is not particularly limited. At a plurality ofIn the embodiment (2), the (meth) acrylate containing an alicyclic hydrocarbon group/(meth) acrylic acid C_1-20The weight ratio of the alkyl ester may be, for example, 10/90 or more, 20/80 or more, or 30/70 or more, and 90/10 or less, 80/20 or less, or 70/30 or less.

As the constituent monomer component of the acrylic oligomer, a functional group-containing monomer may be used as needed in addition to the above (meth) acrylate monomer. Examples of the functional group-containing monomer include monomers having a nitrogen atom-containing heterocycle such as N-vinyl-2-pyrrolidone and N-acryloylmorpholine; amino group-containing monomers such as N, N-dimethylaminoethyl (meth) acrylate; amide group-containing monomers such as N, N-diethyl (meth) acrylamide; AA. Carboxyl group-containing monomers such as MAA; hydroxyl group-containing monomers such as 2-hydroxyethyl (meth) acrylate. These functional group-containing monomers may be used alone in 1 kind or in combination of 2 or more kinds. When the functional group-containing monomer is used, the proportion of the functional group-containing monomer in the total monomer components constituting the acrylic oligomer may be, for example, 1% by weight or more, 2% by weight or more, or 3% by weight or more, and may be, for example, 15% by weight or less, 10% by weight or less, or 7% by weight or less. The acrylic oligomer may not use a functional group-containing monomer.

Examples of suitable acrylic oligomers include homopolymers of dicyclopentyl methacrylate (DCPMA), cyclohexyl methacrylate (CHMA), isobornyl methacrylate (IBXMA), isobornyl acrylate (IBXA), dicyclopentyl acrylate (DCPA), 1-adamantyl methacrylate (ADMA), and 1-adamantyl acrylate (ADA), copolymers of DCPMA and MMA, copolymers of DCPMA and IBXMA, copolymers of ADA and Methyl Methacrylate (MMA), copolymers of CHMA and isobutyl methacrylate (IBMA), copolymers of CHMA and IBXMA, copolymers of CHMA and Acryloylmorpholine (ACMO), copolymers of CHMA and Diethylacrylamide (DEAA), and copolymers of CHMA and AA.

The acrylic oligomer can be formed by polymerizing its constituent monomer components. The polymerization method and polymerization method are not particularly limited, and various conventionally known polymerization methods (for example, solution polymerization, emulsion polymerization, bulk polymerization, photopolymerization, and radiation polymerization) can be used in a suitable manner. The type of the polymerization initiator (e.g., azo polymerization initiator) that can be used as needed is basically as exemplified with respect to the synthesis of the acrylic polymer (a), and the amount of the polymerization initiator and the amount of the chain transfer agent (e.g., thiol) that is optionally used are appropriately set according to the technical common knowledge so as to have a desired molecular weight, and thus detailed description is omitted.

When the acrylic oligomer is contained in the pressure-sensitive adhesive layer or the pressure-sensitive adhesive composition, the content thereof may be, for example, 0.01 parts by weight or more relative to 100 parts by weight of the polymer (a), and may be 0.05 parts by weight or more, or 0.1 parts by weight or more, or 0.2 parts by weight or more from the viewpoint of obtaining higher effects. From the viewpoint of compatibility with the polymer (a), the content of the acrylic oligomer per 100 parts by weight of the polymer (a) is preferably less than 50 parts by weight, more preferably less than 30 parts by weight, even more preferably 25 parts by weight or less, and may be, for example, 10 parts by weight or less, or may be 5 parts by weight or less, or 1 part by weight or less. An adhesive layer or an adhesive composition containing no acrylic oligomer may be used.

(crosslinking agent)

In the adhesive layer, a crosslinking agent may be used as needed. In the pressure-sensitive adhesive sheet disclosed herein, the crosslinking agent is typically contained in the pressure-sensitive adhesive layer in a form after a crosslinking reaction. The cohesive force of the adhesive layer and the like can be appropriately adjusted by using the crosslinking agent. In addition, for example, in the case of an adhesive sheet in which the adhesive layer contains the photoreactive monomer (B), by using a crosslinking agent in combination with the photoreactive monomer (B), it is possible to suitably achieve both flexibility of the adhesive layer before photocuring of the photoreactive monomer and deformation resistance of the adhesive layer after photocuring.

The type of the crosslinking agent is not particularly limited, and may be selected from conventionally known crosslinking agents, for example, depending on the composition of the adhesive composition, so that the crosslinking agent can exert an appropriate crosslinking function in the adhesive layer. Examples of the crosslinking agent that can be used include an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an oxazoline-based crosslinking agent, an aziridine-based crosslinking agent, a carbodiimide-based crosslinking agent, a melamine-based crosslinking agent, a urea-based crosslinking agent, a metal alkoxide-based crosslinking agent, a metal chelate-based crosslinking agent, a metal salt-based crosslinking agent, a hydrazine-based crosslinking agent, and an amine-based crosslinking agent. These can be used alone in 1 or a combination of 2 or more.

As the isocyanate-based crosslinking agent, a polyfunctional isocyanate compound having 2 or more functions can be used. Examples thereof include aromatic isocyanates such as toluene diisocyanate, xylene diisocyanate, polymethylene polyphenyl diisocyanate, tris (p-isocyanatophenyl) thiophosphate, and diphenylmethane diisocyanate; alicyclic isocyanates such as isophorone diisocyanate; aliphatic isocyanates such as hexamethylene diisocyanate, and the like. Examples of commercially available products include isocyanate adducts such as trimethylolpropane/tolylene diisocyanate trimer adduct (product name "Coronate L" manufactured by Tosoh corporation), trimethylolpropane/hexamethylene diisocyanate trimer adduct (product name "Coronate HL" manufactured by Tosoh corporation), isocyanurate of hexamethylene diisocyanate (product name "Coronate HX" manufactured by Tosoh corporation), trimethylolpropane/xylylene diisocyanate adduct (product name "Takenate D-110N" manufactured by Mitsui chemical corporation), and the like.

As the epoxy crosslinking agent, a substance having 2 or more epoxy groups in 1 molecule can be used without particular limitation. Preferably an epoxy crosslinking agent having 3 to 5 epoxy groups in 1 molecule. Specific examples of the epoxy-based crosslinking agent include N, N' -tetraglycidyl-m-xylylenediamine, 1, 3-bis (N, N-diglycidylaminomethyl) cyclohexane, 1, 6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, and polyglycerol polyglycidyl ether. Commercially available products of the epoxy-based crosslinking agent include trade names "TETRAD-X" and "TETRAD-C" manufactured by Mitsubishi gas chemical, trade name "Epichlone CR-5L" manufactured by DIC, trade name "DENACOL EX-512" manufactured by Nagase ChemteX Corporation, and trade name "TEPIC-G" manufactured by Nissan chemical industries, Ltd.

As the oxazoline-based crosslinking agent, a substance having 1 or more oxazoline groups in 1 molecule can be used without particular limitation.

Examples of the aziridine-based crosslinking agent include trimethylolpropane tris [3- (1-aziridinyl) propionate ], trimethylolpropane tris [3- (1- (2-methyl) aziridinyl propionate ], and the like.

As the carbodiimide-based crosslinking agent, a low molecular weight compound or a high molecular weight compound having 2 or more carbodiimide groups can be used.

In several ways, peroxides can also be used as crosslinking agents. Examples of the peroxide include di (2-ethylhexyl) peroxydicarbonate, di (4-tert-butylcyclohexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-hexyl peroxypivalate, tert-butyl peroxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,3, 3-tetramethylbutyl peroxyisobutyrate, and dibenzoyl peroxide. Among them, peroxides having particularly excellent crosslinking reaction efficiency include bis (4-t-butylcyclohexyl) peroxydicarbonate, dilauroyl peroxide, and dibenzoyl peroxide. When a peroxide is used as the polymerization initiator, the peroxide remaining in the polymerization reaction without being used may be used for the crosslinking reaction. In this case, the residual amount of the peroxide is determined quantitatively, and when the proportion of the peroxide does not satisfy a predetermined amount, the peroxide may be added to the solution in a predetermined amount as needed. The peroxide can be quantified by the method described in Japanese patent application No. 4971517.

The amount of the crosslinking agent used (the total amount of 2 or more crosslinking agents used) is not particularly limited. From the viewpoint of achieving a pressure-sensitive adhesive that exhibits adhesive properties such as adhesive strength and cohesive strength in a balanced manner, the amount of the crosslinking agent to be used is preferably about 5 parts by weight or less, and may be 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, or less than 1 part by weight, based on 100 parts by weight of the polymer (a). In the case of using the crosslinking agent and the photoreactive monomer (B) in combination, the amount of the crosslinking agent to be used may be, for example, 0.80 parts by weight or less, 0.60 parts by weight or less, 0.30 parts by weight or less, or 0.10 parts by weight or less based on 100 parts by weight of the polymer (a) from the viewpoint of easily and appropriately exerting the effects of the combined use. The lower limit of the amount of the crosslinking agent is not particularly limited, and it may be used in an amount of more than 0 part by weight relative to 100 parts by weight of the polymer (a). In some embodiments, the amount of the crosslinking agent to be used may be, for example, 0.001 parts by weight or more, 0.01 parts by weight or more, or 0.03 parts by weight or more, based on 100 parts by weight of the polymer (a).

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

In order to allow the crosslinking reaction to proceed more efficiently, a crosslinking catalyst may also be used. As the crosslinking catalyst, tetra-n-butyl titanate, tetra-isopropyl titanate, iron acetylacetonate (B)

Iron (III)), butyltin oxide, dioctyltin laurate, and other metal-based crosslinking catalysts. Among them, tin-based crosslinking catalysts such as dioctyltin laurate are preferable. The amount of the crosslinking catalyst used is not particularly limited. The crosslinking catalyst may be used in an amount of, for example, about 0.0001 part by weight or more per 100 parts by weight of the polymer (A),About 0.001 part by weight or more and about 0.005 part by weight or more. The amount of the organic solvent may be about 1 part by weight or less, about 0.1 part by weight or less, about 0.05 part by weight or less, or the like.

The adhesive composition used for forming the adhesive layer may contain a compound that causes keto-enol tautomerism as a crosslinking retarder, if desired. For example, in an adhesive composition containing an isocyanate-based crosslinking agent or an adhesive composition which can be used by adding an isocyanate-based crosslinking agent, a compound which causes keto-enol tautomerism can be preferably used. This can exert an effect of extending the pot life of the adhesive composition.

As the compound in which keto-enol tautomerism occurs, various β -dicarbonyl compounds can be used. Specific examples thereof include β -diketones such as acetylacetone and 2, 4-hexanedione; acetoacetic acid esters such as methyl acetoacetate and ethyl acetoacetate; propionyl acetates such as propionyl ethyl acetate; isobutyrylacetic acid esters such as isobutyrylacetic acid ethyl ester; malonic esters such as methyl malonate and ethyl malonate. Among these compounds, acetylacetone and acetoacetates are suitable. The compounds which cause keto-enol tautomerism may be used in 1 kind alone or in combination of 2 or more kinds.

The amount of the compound which causes keto-enol tautomerism may be, for example, 0.1 to 20 parts by weight, or 0.5 to 15 parts by weight, or 1 to 10 parts by weight, or 1 to 5 parts by weight, based on 100 parts by weight of the polymer (a).

(silane coupling agent)

The adhesive layer of the adhesive sheet disclosed herein may contain a silane coupling agent as desired. The use of the silane coupling agent can improve the peel strength of the pressure-sensitive adhesive sheet from an adherend (e.g., a glass plate). The adhesive layer containing a silane coupling agent may be suitably formed using an adhesive composition containing a silane coupling agent. In the pressure-sensitive adhesive composition, the silane coupling agent is preferably contained in a free form in the pressure-sensitive adhesive composition from the viewpoint of gel inhibition and the like. In addition, in some aspects, 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 an increase in peel force. Here, "free form" means that the silane coupling agent is not chemically bonded to other components contained in the adhesive composition or the adhesive layer.

Examples of the silane coupling agent include silicon compounds having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane and 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane; amino-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane and N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane; 3-chloropropyltrimethoxysilane; (meth) acrylic group-containing silane coupling agents such as acetoacetyl group-containing trimethoxysilane, 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane; and isocyanate group-containing silane coupling agents such as 3-isocyanatopropyltriethoxysilane. In some embodiments, the above-described effect can be more preferably exerted by using a silane coupling agent having a trialkoxysilyl group. As preferred silane coupling agents among them, 3-glycidoxypropyltrimethoxysilane and acetoacetyl group-containing trimethoxysilane can be exemplified.

The amount of the silane coupling agent to be used is not particularly limited, and may be set so as to obtain a desired effect. In some embodiments, the amount of the silane coupling agent to be used may be, for example, 0.001 parts by weight or more per 100 parts by weight of the polymer (a), and from the viewpoint of obtaining higher effects, may be 0.01 parts by weight or more, may be 0.05 parts by weight or more, and may be 0.1 parts by weight or more. From the viewpoint of gel inhibition of the adhesive composition, the amount of the silane coupling agent to be used is preferably 3 parts by weight or less, and may be 1 part by weight or less, or may be 0.5 part by weight or less, relative to 100 parts by weight of the polymer (a).

(photopolymerization initiator)

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein may contain a photopolymerization initiator as necessary for the purpose of improving or imparting photocurability. As the photopolymerization initiator, as with the photopolymerization initiator exemplified as the photopolymerization initiator usable for the synthesis of the polymer (a), a ketal-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, a benzoin ether-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, an α -keto alcohol-based photopolymerization initiator, an aromatic sulfonyl chloride-based photopolymerization initiator, a photoactive oxime-based photopolymerization initiator, a benzoin-based photopolymerization initiator, a benzil-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, a thioxanthone-based photopolymerization initiator, and the like can be used. The photopolymerization initiator may be used alone in 1 kind or in an appropriate combination of 2 or more kinds.

Specific examples of the ketal-based photopolymerization initiator include 2, 2-dimethoxy-1, 2-diphenylethan-1-one and the like.

Specific examples of the acetophenone photopolymerization initiator include 1-hydroxycyclohexyl-phenyl-ketone, 4-phenoxydichloroacetophenone, 4-tert-butyl-dichloroacetophenone, 1- [4- (2-hydroxyethoxy) -phenyl ] -2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, methoxyacetophenone and the like.

Specific examples of the benzoin ether-based photopolymerization initiator include benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, and benzoin isobutyl ether, and substituted benzoin ethers such as methyl anisole.

Specific examples of the acylphosphine oxide-based photopolymerization initiator 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, bis (2, 6-dimethoxybenzoyl) -2,4, 4-trimethylpentylphosphine oxide, and the like.

Specific examples of the α -ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone and 1- [4- (2-hydroxyethyl) phenyl ] -2-methylpropan-1-one. Specific examples of the aromatic sulfonyl chloride-based photopolymerization initiator include 2-naphthalenesulfonyl chloride and the like. Specific examples of the optically active oxime-based photopolymerization initiator include 1-phenyl-1, 1-propanedione-2- (O-ethoxycarbonyl) -oxime and the like. Specific examples of the benzoin-based photopolymerization initiator include benzoin and the like. Specific examples of the benzil-based photopolymerization initiator include benzil and the like.

Specific examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3' -dimethyl-4-methoxybenzophenone, polyvinyl benzophenone (polyvinylbenzophenone), and α -hydroxycyclohexyl phenyl ketone.

Specific examples of the thioxanthone-based photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2, 4-dimethylthioxanthone, isopropylthioxanthone, 2, 4-dichlorothioxanthone, 2, 4-diethylthioxanthone, isopropylthioxanthone, 2, 4-diisopropylthioxanthone, and dodecylthioxanthone.

The content of the photopolymerization initiator in the pressure-sensitive adhesive layer is not particularly limited, and may be set so as to exhibit a desired effect as appropriate. In some embodiments, the content of the photopolymerization initiator may be, for example, about 0.005 parts by weight or more, preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, and may be 0.10 parts by weight or more, or may be 0.15 parts by weight or more, or may be 0.20 parts by weight or more, based on 100 parts by weight of the polymer (a) contained in the pressure-sensitive adhesive layer. The increase in the content of the photopolymerization initiator tends to improve the photocurability of the adhesive layer. The content of the photopolymerization initiator is preferably 10 parts by weight or less, more preferably 7 parts by weight or less, and may be 5 parts by weight or less, and may be 3 parts by weight or less, 2 parts by weight or less, and may be 1 part by weight or less, based on 100 parts by weight of the polymer (a). From the viewpoint of improving the storage stability (e.g., stability against photodegradation) of the adhesive sheet, it is advantageous not to contain an excessive amount of the photopolymerization initiator.

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

The pressure-sensitive adhesive layer or the pressure-sensitive adhesive composition of the pressure-sensitive adhesive sheet disclosed herein may contain, as other optional components, various additives commonly used in the field of pressure-sensitive adhesives, such as a tackifier resin (e.g., rosin-based, petroleum-based, terpene-based, phenol-based, or ketone-based tackifier resin), a viscosity modifier (e.g., thickener), a leveling agent, a plasticizer, a filler, a colorant such as a pigment or a dye, a stabilizer, an antiseptic, and an anti-aging agent, as required. For such various additives, conventionally known substances can be used by conventional methods, and are not particularly characterized in the present invention, and therefore, detailed descriptions thereof are omitted.

The technology disclosed herein can exhibit good adhesion without using the above tackifier resin. Therefore, in some embodiments, the content of the tackifier resin in the pressure-sensitive adhesive layer or the pressure-sensitive adhesive composition may be, for example, less than 10 parts by weight, and further less than 5 parts by weight, based on 100 parts by weight of the polymer (a). The content of the tackifier resin may be less than 1 part by weight (for example, less than 0.5 part by weight) or less than 0.1 part by weight (0 part by weight or more and less than 0.1 part by weight). The adhesive layer or the adhesive composition may contain no tackifying resin.

From the viewpoint of transparency, the amount of the components other than the polymer (a) and the photoreactive monomer (B) used as needed in the pressure-sensitive adhesive layer (or the pressure-sensitive adhesive composition used for forming the pressure-sensitive adhesive layer) is preferably limited. In the technique disclosed herein, the amount of the components other than the polymer (a) and the photoreactive monomer (B) in the adhesive layer is suitably 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 the psa sheets of several embodiments, the amount of components other than the polymer (a) and the photoreactive monomer (B) in the psa layer may be about 5 wt% or less, about 3 wt% or less, or about 1.5 wt% or less (e.g., about 1 wt% or less).

< morphology of adhesive composition >

The pressure-sensitive adhesive layer can be formed using a pressure-sensitive adhesive composition containing a monomer component having the above-described composition in the form of a polymer, an unpolymerized product (i.e., a product in which polymerizable functional groups are not reacted), or a mixture thereof. The adhesive composition may be in various forms such as: a composition (solvent-based adhesive composition) in which an adhesive (adhesive component) is contained in an organic solvent; a composition in which a binder is dispersed in an aqueous solvent (water-dispersible binder composition); a composition prepared so as to be cured by an active energy ray such as ultraviolet ray or radiation to form a pressure-sensitive adhesive (active energy ray-curable pressure-sensitive adhesive composition), a hot-melt pressure-sensitive adhesive composition which is applied in a molten state under heating and forms a pressure-sensitive adhesive when cooled to around room temperature, and the like. From the viewpoints of ease of preparation of the adhesive composition, ease of formation of the adhesive layer, and the like, a solvent-based adhesive composition is preferably used in some embodiments. The solvent-based adhesive composition can be preferably prepared using the polymer (a) as a polymer obtained by solution polymerization of monomer components.

In the present specification, the term "active energy ray" refers to an energy ray having energy capable of initiating a chemical reaction such as a polymerization reaction, a crosslinking reaction, or decomposition of an initiator. Examples of the active energy rays include light such as ultraviolet rays, visible rays, and infrared rays, radiation such as α rays, β rays, γ rays, electron beams, neutron beams, and X-rays, and the like.

The adhesive composition typically contains at least a part (may be a part of the monomer species or a part of the amount) of the monomer components of the composition in the form of a polymer. The polymerization method for forming the polymer is not particularly limited, and various conventionally known polymerization methods can be suitably used. For example, thermal polymerization such as solution polymerization, emulsion polymerization, and bulk polymerization (typically, in the presence of a thermal polymerization initiator); photopolymerization by irradiation with light such as ultraviolet rays (typically in the presence of a photopolymerization initiator); radiation polymerization by irradiation with radiation such as β -rays and γ -rays. In these polymerization methods, the mode of polymerization is not particularly limited, and the polymerization can be carried out by appropriately selecting conventionally known monomer supply methods, polymerization conditions (temperature, time, pressure, light irradiation amount, radiation irradiation amount, and the like), materials used other than the monomers (polymerization initiator, surfactant, and the like), and the like.

In the polymerization, a known or conventional photopolymerization initiator or thermal polymerization initiator can be used depending on the polymerization method, polymerization system, and the like. Examples of the photopolymerization initiator and the thermal polymerization initiator are as described above, and therefore, a repetitive description thereof will be omitted. Such polymerization initiators may be used in 1 kind alone or in appropriate combinations of 2 or more kinds.

(adhesive composition comprising a Polymer of monomer Components and an unpolymerized)

Several ways of adhesive compositions comprise: a polymerization reaction product of a monomer mixture containing at least a portion of the monomer components (starting monomers) of the composition. Typically, a part of the monomer component is contained in the form of a polymer, and the remaining part is contained in the form of an unreacted monomer. The polymerization reaction product of the above monomer mixture may be prepared by polymerizing at least a portion of the monomer mixture.

The polymerization reaction product is preferably a partial polymer of the monomer mixture. Such a partial polymer is a mixture of a polymer derived from the above monomer mixture and an unreacted monomer, and is typically in a slurry state (liquid state having viscosity). Hereinafter, the partial polymer having such a property may be referred to as "monomer slurry", "polymer slurry" or simply "slurry".

The polymerization method for obtaining the polymerization reaction product is not particularly limited, and various polymerization methods such as those described above can be appropriately selected and used. From the viewpoint of efficiency and simplicity, a photopolymerization method is preferably employed. When photopolymerization is used, the polymerization conversion rate of the monomer mixture can be easily controlled by using polymerization conditions such as the amount of light irradiation (light amount).

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

The adhesive composition containing a partial polymer of the above monomer mixture can be easily obtained by, for example, partially polymerizing a monomer mixture containing all raw material monomers by an appropriate polymerization method (e.g., photopolymerization method). The pressure-sensitive adhesive composition containing the partial polymer may contain other components (for example, a photopolymerization initiator, a polyfunctional monomer, a crosslinking agent, an acrylic oligomer described later) used as needed. The method for compounding such other components is not particularly limited, and may be, for example, previously contained in the monomer mixture or added to the partial polymer.

The pressure-sensitive adhesive composition disclosed herein may be in a form in which a complete polymer of a monomer mixture containing a part of the monomers among the monomer components (raw material monomers) is dissolved in the remaining monomers or a partial polymer thereof. Adhesive compositions of this morphology are also included in the example of polymeric and non-polymeric adhesive compositions containing monomeric components. In the present specification, the term "complete polymer" means that the polymerization conversion rate exceeds 95% by weight.

As a curing method (polymerization method) in forming the adhesive from the adhesive composition containing the polymer and the non-polymer of the monomer component as described above, a photopolymerization method can be preferably employed. For the adhesive composition containing the polymerization reaction product prepared by the photopolymerization method, the photopolymerization method is particularly suitably employed as the curing method thereof. Since the polymerization reaction product obtained by the photopolymerization method already contains a photopolymerization initiator, when the adhesive composition containing the polymerization reaction product is further cured to form an adhesive, photocuring can be performed without adding a new photopolymerization initiator. Alternatively, a pressure-sensitive adhesive composition having a composition in which a photopolymerization initiator is added to a polymerization reaction product produced by a photopolymerization method as needed may be used. The additional photopolymerization initiator may be the same as or different from the photopolymerization initiator used for the preparation of the polymerization reaction product. The adhesive composition prepared by a method other than photopolymerization can be made photocurable by adding a photopolymerization initiator. The photocurable adhesive composition has an advantage that even a thick adhesive layer can be easily formed. In some preferred embodiments, photopolymerization in forming the adhesive from the adhesive composition may be performed by ultraviolet irradiation. The ultraviolet irradiation may be performed using a known high-pressure mercury lamp, low-pressure mercury lamp, metal halide lamp, or the like.

(adhesive composition comprising monomer component in the form of complete polymer)

Several other forms of adhesive compositions comprise the monomeric components of the adhesive composition in a fully polymeric form. Such a pressure-sensitive adhesive composition may be in the form of, for example, a solvent-type pressure-sensitive adhesive composition containing an acrylic polymer as a complete polymer of a monomer component in an organic solvent, or a water-dispersion type pressure-sensitive adhesive composition in which the acrylic polymer is dispersed in an aqueous solvent.

(thickness of adhesive layer)

The thickness of the adhesive layer is not particularly limited. The thickness of the pressure-sensitive adhesive layer may be, for example, about 1 μm to 500 μm, and may be, for example, about 3 μm to 500 μm. In some embodiments, the thickness of the pressure-sensitive adhesive layer is suitably 5 μm or more, and may be, for example, 10 μm or more, preferably 20 μm or more, more preferably 25 μm or more, or may exceed 25 μm. When the thickness of the pressure-sensitive adhesive layer is increased, the stress dispersion ability in the pressure-sensitive adhesive layer tends to be increased. This may advantageously contribute to a reduction of optical distortions. In addition, a thick pressure-sensitive adhesive layer tends to have excellent level difference following properties, and is likely to absorb deformation due to foreign matter or the like. Impact resistance tends to be improved. The technique disclosed herein can be preferably implemented in such a manner that the thickness of the adhesive layer is, for example, 30 μm or more. The thickness of the pressure-sensitive adhesive layer may be 35 μm or more, may be 40 μm or more, may be 45 μm or more, may be 50 μm or more, may be 75 μm or more, and may be 90 μm or more. On the other hand, when the thickness of the pressure-sensitive adhesive layer is increased, the optical path through the pressure-sensitive adhesive layer is also increased, and thus optical distortion is easily observed. Therefore, in some embodiments, the thickness of the pressure-sensitive adhesive layer is suitably 200 μm or less, for example, 150 μm or less, or 120 μm or less, or preferably 100 μm or less, or more preferably 70 μm or less, or even more preferably 50 μm or less, or even 35 μm or less. An adhesive layer having such a thickness more favorably suppresses deformation of the adhesive layer. In the case of the technique disclosed herein, a bonding having high deformation resistance and high impact resistance can be formed by a configuration including a pressure-sensitive adhesive layer having a thickness of, for example, 70 μm or less.

The thickness of the adhesive layer can be measured by an 1/1000mm gauge dial gauge of a planimeter. For example, in the case of the structure of the release film/adhesive layer/release film, the total thickness is measured by an 1/1000mm gauge dial gauge of a planimeter, and the thickness of the release film is subtracted therefrom to calculate the thickness.

(peak temperature of tan. delta.)

The adhesive constituting the adhesive layer disclosed herein preferably has a loss tangent tan δ peak top temperature in the range of-50 ℃ to 0 ℃. When a binder having a peak of tan δ in a low temperature region is used, good impact resistance is easily obtained. The peak top temperature of the loss tangent tan δ of the adhesive can be determined by the following method. That is, the storage modulus G' and the loss modulus G ″ were measured by performing dynamic viscoelasticity measurement under the same conditions as the measurement of the storage modulus at 25 ℃. Then, the following formula: the loss tangent tan δ was calculated as G "/G', and the temperature dependence thereof was plotted, whereby the temperature corresponding to the peak top thereof (the temperature at which the tan δ curve becomes maximum) was obtained.

(storage modulus at 25 ℃ C.)

The storage modulus at 25 ℃ (storage modulus at 25 ℃) of the pressure-sensitive adhesive layer is appropriately set depending on the intended use, the mode of use, and the like, and is not limited to a specific range. The storage modulus at 25 ℃ is about 4X 10 from the viewpoints of adhesion characteristics such as deformation resistance, heat resistance and the like⁴Pa or more is suitably about 6X 10⁴Pa or more, more preferably about 8X 10⁴Pa or more, and may be about 1.0X 10⁵Pa or more, and may be about 1.2X 10⁵Pa or more, and may be about 1.5X 10⁵Pa or more, and may be about 1.8X 10⁵Pa or above. The pressure-sensitive adhesive layer having a high storage modulus at 25 ℃ tends to have excellent press deformation resistance. The storage modulus at 25 ℃ is, for example, less than 1X 10⁷Pa, about 1X 10⁶Pa or less is suitable. The storage modulus at 25 ℃ is preferably about 5.0X 10 from the viewpoint of suitably exhibiting adhesive properties such as adhesiveness⁵Pa or less, more preferably about 3.0X 10⁵Pa or less, and more preferably about 2.0X 10⁵Pa or less, and may be about 1.4X 10⁵Pa or less, or about 1.0X 10⁵Pa or less. The storage modulus at 25 ℃ of the pressure-sensitive adhesive sheet (typically, a substrate-free pressure-sensitive adhesive sheet) is also preferably set to the above-exemplified range. The storage modulus at 25 ℃ can be adjusted by the molecular weight, molecular structure, concentration, degree of crosslinking, etc. of the base polymer. The storage modulus at 25 ℃ was measured by the following method. The same applies to the embodiments described later.

[ storage modulus at 25 ]

A plurality of pressure-sensitive adhesive sheets or pressure-sensitive adhesive layers to be measured were stacked to prepare a pressure-sensitive adhesive layer having a thickness of about 2 mm. The pressure-sensitive adhesive layer was punched out into a disk shape having a diameter of 7.9mm, the obtained sample was held and fixed by parallel plates, and dynamic viscoelasticity measurement was performed under the following conditions using a viscoelasticity tester (for example, TA Instruments, manufactured by inc., ARES, or equivalent thereof) to obtain a storage modulus G' (25 ℃) at 25 ℃ (Pa).

Measurement mode: shear mode

Temperature range: -70 ℃ to 150 DEG C

Temperature increase rate: 5 ℃/min

Measurement frequency: 1Hz

(gel fraction)

The gel fraction of the pressure-sensitive adhesive layer is appropriately set according to the intended use, the mode of use, and the like, and is not limited to a specific range. The gel fraction is preferably about 99% by weight or less, and about 97% by weight or less, for example. In some preferred embodiments, the gel fraction is about 95 wt% or less, more preferably about 92 wt% or less, and may be about 88 wt% or less, or may be about 75 wt% or less, or may be about 65 wt% or less, from the viewpoint of level difference following ability and the like. The pressure-sensitive adhesive layer having the gel fraction described above can satisfactorily follow the unevenness of a print, for example, when the print such as a logo is formed on the surface of an adherend, without impairing the visual recognition. From the viewpoint of exhibiting good adhesive properties and viscoelastic properties, the gel fraction of the adhesive layer is preferably, for example, about 10 wt% or more and about 20 wt% or more. From the viewpoint of deformation resistance and the like, the gel fraction is preferably about 30% by weight or more, more preferably about 40% by weight, and may be about 50% by weight or more, may be about 65% by weight or more, and may be about 75% by weight or more. The gel fraction of the pressure-sensitive adhesive sheet (typically, a substrate-free pressure-sensitive adhesive sheet) is also preferably within the above-described range. The gel fraction can be adjusted by the molecular weight, molecular structure, concentration, degree of crosslinking, etc. of the base polymer. The gel fraction was measured by the following method. The same applies to the embodiments described later.

[ gel fraction ]

A prescribed amount of the adhesive sample (weight Wg)₁) With a porous polytetrafluoroethylene membrane having an average pore diameter of 0.2 μm (weight Wg)₂) Wrapping into a bag with cotton thread (weight Wg)₃) And (6) tying the mouth. As the porous Polytetrafluoroethylene (PTFE) membrane, a product of "Nitoflon (registered trademark) NTF 1122" (average pore diameter 0.2 μm, porosity 75%, thickness 85 μm) available from Ninto electric corporation or a product equivalent thereof was used.

The coating was immersed in a sufficient amount of ethyl acetate and kept at room temperature (typically 23 ℃) for 7 days to elute only the sol component in the pressure-sensitive adhesive layer to the outside of the film, and then the coating was taken out, ethyl acetate adhering to the outer surface was wiped off, the coating was dried at 130 ℃ for 2 hours, and the weight (Wg) of the coating was measured₄). The gel fraction of the pressure-sensitive adhesive layer was determined by substituting each value into the following equation.

Gel fraction (%) [ (Wg)₄-Wg₂-Wg₃)/Wg₁]×100

The pressure-sensitive adhesive sheet disclosed herein includes a pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is photo-cured after being adhered to an adherend, and therefore, at least a photocurable pressure-sensitive adhesive sheet (for example, a pressure-sensitive adhesive sheet of example 4 having a pressure-sensitive adhesive C described later) is used at an illuminance of 300mW/cm²And a cumulative light amount of 3000mJ/cm²The test specimen was cured at 50 ℃ for 48 hours under irradiation with ultraviolet light, and the peak temperature of tan δ, the storage modulus at 25 ℃, the gel fraction, the total light transmittance, the haze value, the maximum height Rz of the adhesive surface, the arithmetic average roughness Ra, the adhesive force, the elastic modulus by the tensile test, and the impact resistance were measured. In the case where the release film is transparent, the ultraviolet irradiation treatment is preferably performed in a state where the pressure-sensitive adhesive sheet (typically, a pressure-sensitive adhesive layer) is sandwiched between transparent release films.

< support substrate >

The pressure-sensitive adhesive sheet of the present invention may be in the form of a pressure-sensitive adhesive sheet with a support substrate. The material of the support substrate is not particularly limited, and may be appropriately selected depending on the intended use, the mode of use, and the like of the adhesive sheet. Non-limiting examples of the support substrate that can be used include resin films such as polyolefin films mainly composed of polyolefins such as polypropylene and ethylene-propylene copolymers, polyester films mainly composed of polyesters such as polyethylene terephthalate and polybutylene terephthalate, and polyvinyl chloride films mainly composed of polyvinyl chloride; foam sheets formed of foams such as polyurethane foam, polyethylene foam, and polychloroprene foam; woven and nonwoven fabrics formed from various fibrous materials (natural fibers such as hemp and cotton, synthetic fibers such as polyester and vinylon, and semi-synthetic fibers such as acetate fibers, etc.) alone or by blending; paper such as japanese paper, fine paper, kraft paper, crepe paper, and the like; metal foils such as aluminum foil and copper foil. The support base material may be a composite of these. Examples of the support substrate having such a composite structure include a metal layer (e.g., a metal foil, a continuous or discontinuous metal sputtering layer, a metal deposition layer, a metal plating layer, etc.), a support substrate having a structure in which a metal oxide layer and the resin film are laminated, and a resin sheet reinforced with inorganic fibers such as glass cloth. The support base may correspond to an optical member (for example, an optical film) described later, or may be a transparent member formed of a transparent material (for example, a resin material having transparency, glass, or the like).

As the support substrate of the pressure-sensitive adhesive sheet disclosed herein, various films (hereinafter also referred to as support films) can be preferably used. The support film may be a porous film such as a foam film or a nonwoven fabric sheet, a non-porous film, or a film having a structure in which a porous layer and a non-porous layer are laminated. In some embodiments, as the supporting film, a supporting film including a resin film capable of independently maintaining a shape (a self-supporting type or an independent type) as a base film can be preferably used. Here, the "resin film" is a non-porous structure and typically a (non-porous) resin film substantially free of bubbles. Therefore, the resin film is a concept different from a foam film and a nonwoven fabric. The resin film may have a single-layer structure or a multilayer structure (for example, a three-layer structure) having two or more layers.

Examples of the resin material constituting the resin film include polyester, polyolefin, polycycloolefin derived from a monomer having an aliphatic ring structure such as a norbornene structure, nylon 6, nylon 66, Polyamide (PA) such as partially aromatic polyamide, Polyimide (PI), Polyamideimide (PAI), polyether ether ketone (PEEK), polyether sulfone (PES), polyphenylene sulfide (PPS), Polycarbonate (PC), and Polyurethane (PU), and resins such as fluorine resins such as ethylene-vinyl acetate copolymers (EVA), polystyrene, polyvinyl chloride, polyvinylidene chloride, and Polytetrafluoroethylene (PTFE), acrylic resins such as polymethyl methacrylate, cellulose polymers such as cellulose diacetate and cellulose triacetate, vinyl butyral polymers, acrylate polymers, polyoxymethylene polymers, and epoxy polymers. The resin film may be formed using a resin material containing 1 kind of such resin alone, or may be formed using a resin material obtained by blending 2 or more kinds of such resins. The resin film may be unstretched or stretched (for example, uniaxially stretched or biaxially stretched).

Preferred examples of the resin material constituting the resin film include a polyester resin, a PPS resin, and a polyolefin resin. The polyester resin is a resin containing a polyester in a proportion of more than 50% by weight. Similarly, the PPS resin refers to a resin containing PPS in a proportion of more than 50 wt%, and the polyolefin resin refers to a resin containing polyolefin in a proportion of more than 50 wt%.

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

As the polyolefin resin, 1 kind of polyolefin alone or 2 or more kinds of polyolefins in combination may be used. The polyolefin may be, for example, a homopolymer of an α -olefin, a copolymer of 2 or more α -olefins, a copolymer of 1 or 2 or more α -olefins with other vinyl monomers, or the like. Specific examples thereof include ethylene-propylene copolymers such as Polyethylene (PE), polypropylene (PP), poly-1-butene, poly-4-methyl-1-pentene and ethylene-propylene rubber (EPR), ethylene-propylene-butene copolymers, ethylene-vinyl alcohol copolymers and ethylene-ethyl acrylate copolymers. Both Low Density (LD) polyolefins and High Density (HD) polyolefins may be used. Examples of the polyolefin resin film include an unstretched polypropylene (CPP) film, a biaxially stretched polypropylene (OPP) film, a Low Density Polyethylene (LDPE) film, a Linear Low Density Polyethylene (LLDPE) film, a Medium Density Polyethylene (MDPE) film, a High Density Polyethylene (HDPE) film, a Polyethylene (PE) film obtained by blending 2 or more kinds of Polyethylenes (PE), and a PP/PE blend film obtained by blending polypropylene (PP) and Polyethylene (PE).

Specific examples of the resin film that can be preferably used as the support base material include a PET film, a PEN film, a PPS film, a PEEK film, a CPP film, and an OPP film. Preferable examples of the film from the viewpoint of strength include a PET film, a PEN film, a PPS film, and a PEEK film. A PET film is a preferable example from the viewpoint of acquisition easiness, dimensional stability, optical characteristics, and the like.

The resin film may contain, as necessary, known additives such as a light stabilizer, an antioxidant, an antistatic agent, a colorant (dye, pigment, etc.), a filler, a slip agent, and an antiblocking agent. The amount of the additive to be blended is not particularly limited, and may be appropriately set according to the use of the pressure-sensitive adhesive sheet and the like.

The method for producing the resin film is not particularly limited. For example, conventionally known common resin film forming methods such as extrusion molding, inflation molding, T-die casting molding, calender roll molding, and the like can be suitably used.

The support base may be a support film substantially composed of such a resin film. The support base may be a support film including an auxiliary layer in addition to the resin film. The auxiliary layer may be disposed on the pressure-sensitive adhesive layer side of the resin film, may be disposed on the opposite side of the pressure-sensitive adhesive layer, or may be disposed on both sides of the resin film. Examples of the auxiliary layer include an optical property adjusting layer (for example, a colored layer and an antireflection layer), a decorative layer (for example, a printed layer, a laminated layer, a continuous or discontinuous metal oxide layer, or the like) for imparting a desired appearance to a support substrate or an adhesive sheet, a conductive layer, an antistatic layer, an undercoat layer, and a release layer.

In several aspects, the support substrate is preferably a plastic film having transparency. In this embodiment, the total light transmittance of the support base material is preferably, for example, about 50% or more, for example, about 70% or more. In some preferred embodiments, the total light transmittance of the support base material is about 85% or more, more preferably about 90% or more, from the viewpoint of visual recognition of an adherend through the pressure-sensitive adhesive sheet. The upper limit of the total light transmittance may be practically about 95% or less, or about 94% or less (e.g., 93% or less).

The total light transmittance of the support substrate can be measured using a haze meter. As the haze meter, the device name "HM-150N" manufactured by color technology research on village or its equivalent may be used.

The thickness of the support substrate is not particularly limited, and may be selected according to the intended use, the mode of use, and the like of the adhesive sheet. The thickness of the support base material may be, for example, 1000 μm or less, and is suitably 500 μm or less, preferably 300 μm or less, and may be 100 μm or less, and may be 70 μm or less, and may be 50 μm or less, and may be 25 μm or less, and may be 10 μm or less, and may be 5 μm or less, from the viewpoint of handling properties (e.g., ease of winding). When the thickness of the support substrate is reduced, the flexibility of the pressure-sensitive adhesive sheet and the following property to the surface shape of the adherend tend to be improved. The thickness of the support base material may be, for example, 2 μm or more, or more than 5 μm or more than 10 μm, from the viewpoint of handling property, processability, and the like. In some embodiments, the thickness of the support base material may be, for example, 20 μm or more, 35 μm or more, or 55 μm or more.

The surface of the support substrate on the side in contact with the pressure-sensitive adhesive layer may be subjected to conventionally known surface treatment such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, coating with a primer (primer), antistatic treatment, or the like, as necessary. Such surface treatment may be treatment for improving adhesion between the support base material and the adhesive layer, in other words, anchoring properties of the adhesive layer to the support base material. The composition of the primer is not particularly limited, and may be appropriately selected from known compositions. The thickness of the undercoat layer is not particularly limited, and is suitably about 0.01 to 1 μm, preferably about 0.1 to 1 μm.

< method for producing pressure-sensitive adhesive sheet with release film >

The method for producing the release film-equipped adhesive sheet disclosed herein is not particularly limited. For example, a pressure-sensitive adhesive layer is formed on a release surface of a release film by applying a pressure-sensitive adhesive composition to the release surface and drying (for example, heat drying) or curing the pressure-sensitive adhesive composition, and a different release film is laminated on a surface of the pressure-sensitive adhesive layer opposite to the release surface, thereby obtaining a release film-equipped pressure-sensitive adhesive sheet. Alternatively, the pressure-sensitive adhesive composition sandwiched between 2 sheets of release films may be dried or cured to form a pressure-sensitive adhesive layer, thereby forming a pressure-sensitive adhesive sheet with a release film. For example, the following methods can be employed for a pressure-sensitive adhesive sheet having a structure of a support substrate: a method in which an adhesive composition is applied to the supporting base material and dried or cured to form an adhesive layer (direct method). In addition, the following method may be adopted: a method (transfer method) in which a pressure-sensitive adhesive layer is formed on a surface having releasability (release surface) by applying a pressure-sensitive adhesive composition to the surface and drying the pressure-sensitive adhesive composition, and the pressure-sensitive adhesive layer is transferred to a supporting substrate.

The curing treatment may include crosslinking (e.g., crosslinking based on the reaction of the above-mentioned crosslinking agent), cooling, and the like. In the case of performing 2 or more curing treatments, they may be performed simultaneously or stepwise. As a method for applying the adhesive composition, various conventionally known methods can be used. Specific examples thereof include roll coating, roll lick coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, blade coating, air knife coating, curtain coating, lip coating, and extrusion coating using a die coater or the like.

The release film-attached adhesive sheet disclosed herein can be suitably produced by a method comprising: the pressure-sensitive adhesive layer is formed by drying or curing a liquid film of the pressure-sensitive adhesive composition on the release surface of the release film. In this method, the adhesive composition (liquid film) in a fluid state is dried or cured in contact with the release surface, and the smoothness of the surface of the adhesive layer formed in contact with the release surface can be accurately controlled. The release surface is typically limited to a maximum height (Rz) of a predetermined value or less, and a highly smooth pressure-sensitive adhesive surface can be stably (with good reproducibility) produced by using a release film having such a release surface.

The release film-attached adhesive sheet disclosed herein can be preferably produced by a method comprising: the liquid film of the pressure-sensitive adhesive composition was cured between the release surfaces of the 1 st release film and the 2 nd release film to form a pressure-sensitive adhesive layer. As a method for disposing a liquid film of the pressure-sensitive adhesive composition between the release surfaces of the 1 st release film and the 2 nd release film, the following method can be employed: a method of applying a liquid pressure-sensitive adhesive composition to the release surface of one release film and then covering the other release film on the liquid film of the pressure-sensitive adhesive composition. As another method, the following methods can be mentioned: a method in which the 1 st release film and the 2 nd release film are supplied between a pair of rollers so that release surfaces thereof face each other, and a liquid adhesive composition is supplied between the release surfaces. The application of the adhesive composition is preferably performed at 80 ℃ or lower, and more preferably at 60 ℃ or lower (for example, 40 ℃ or lower). This suppresses roughening of the pressure-sensitive adhesive layer due to the difference in thermal expansion coefficient between the 1 st release film and the 2 nd release film, and the pressure-sensitive adhesive layer, and enables formation of a pressure-sensitive adhesive surface having higher smoothness.

The total thickness of the pressure-sensitive adhesive sheet with a release film disclosed herein is not particularly limited, and may be, for example, about 30 μm to 1500 μm. Here, the total thickness of the release film-attached pressure-sensitive adhesive sheet is the total thickness of the release film-attached pressure-sensitive adhesive sheet composed of at least 1 release film (including the 1 st release film and the 2 nd release film) and the pressure-sensitive adhesive sheet. In some embodiments, the total thickness of the pressure-sensitive adhesive sheet with a release film may be 60 μm or more, 80 μm or more, 105 μm or more, 125 μm or more, or 140 μm or more, for example. The total thickness of the pressure-sensitive adhesive sheet with a release film may be, for example, 1000 μm or less, 500 μm or less, or 300 μm or less.

< roll body >

According to the present specification, a roll of the release film-equipped adhesive sheet disclosed herein (release film-equipped adhesive sheet roll) is provided in a rolled form. Such a wound body is typically an adhesive sheet including a core (core of a roll) and a release film wound around the core. The shape of the core is not particularly limited, and may be, for example, a solid cylindrical shape, a hollow cylindrical shape (i.e., a cylindrical shape), a hollow or solid polygonal columnar shape, or the like. From the viewpoint of improving handling properties of the roll, a hollow cylindrical or hollow polygonal prism-shaped core is preferably used. A cylindrical core is particularly preferred.

< attachment to adherend >

The method for attaching the pressure-sensitive adhesive sheet disclosed herein to an adherend is not particularly limited. A known or customary crimping method can be employed depending on the intended use and the manner of use. In some preferred embodiments, the pressure-sensitive adhesive sheet is used in a method of attaching to an adherend by a method including photocuring the pressure-sensitive adhesive layer after the pressure-sensitive adhesive sheet is attached to the adherend. An adherend having a pressure-sensitive adhesive sheet laminated thereon is formed by attaching the pressure-sensitive adhesive sheet to the adherend. The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is photocured to obtain a laminate comprising the pressure-sensitive adhesive sheet with the cured pressure-sensitive adhesive layer and the adherend. Therefore, according to the present specification, there is provided a method of attaching an adhesive sheet, which comprises in order: the pressure-sensitive adhesive sheet disclosed herein is bonded to an adherend, and the pressure-sensitive adhesive layer is photocured by irradiating the pressure-sensitive adhesive sheet with ultraviolet light.

< use >)

The adhesive sheet disclosed herein can be used for fixing, joining, molding, decorating, protecting, supporting, etc. members constituting various products. The material constituting at least the surface of the member may be, for example, glass such as alkali glass or alkali-free glass; metal materials such as stainless steel (SUS) and aluminum; and resin materials such as acrylic resins, ABS resins, polycarbonate resins, polyimide resins, polyester resins such as PET, and polystyrene resins. The member may be a member constituting various mobile devices (portable devices), automobiles, home electric appliances, and the like. The surface of the member to which the adhesive sheet is attached may be a coated surface based on a coating material such as an acrylic, polyester, alkyd, melamine, urethane, acid epoxy crosslinking, or a composite thereof (for example, acrylic melamine or alkyd melamine), or a coated surface of a galvanized steel sheet. The member may be, for example, a resin film or an object having a continuous or discontinuous inorganic layer (which may be a metal layer, a metal oxide layer, or the like) on the resin film.

As an example of preferable applications, optical applications are cited. More specifically, the pressure-sensitive adhesive sheet disclosed herein can be preferably used, for example, as a pressure-sensitive adhesive sheet for optical use used for applications of bonding optical members (for bonding optical members), applications of manufacturing products (optical products) using the optical members, and the like.

The optical member is a member having optical characteristics (e.g., polarization, photorefractive, light diffraction, optical rotation, etc.). The optical member is not particularly limited as long as it has optical properties, and examples thereof include members constituting devices (optical devices) such as display devices (image display devices) and input devices, and members used in these devices, such as a polarizing plate, a wavelength plate, a retardation plate, an optical compensation film, a brightness enhancement film, a light guide plate, a reflection film, an antireflection film, a Hard Coat (HC) film, an impact absorption film, an antifouling film, a photochromic film, a light control film, a transparent conductive film (ITO film), and a member in which these are laminated (these may be collectively referred to as a "functional film"). The "plate" and the "film" include plate-like, film-like, sheet-like forms, and the like, and the "polarizing film" includes, for example, "polarizing plate" and "polarizer".

Examples of the display device include a liquid crystal display device, an organic EL (electroluminescence) display device, a PDP (plasma display panel), and electronic paper. The input device may be a touch panel.

The optical member is not particularly limited, and examples thereof include members (e.g., sheet-like, film-like, and plate-like members) made of glass, acrylic resin, polycarbonate, transparent polyimide, PET, and the like.

The method of bonding the optical members using the adhesive sheet disclosed herein is not particularly limited, and examples thereof include (1) a method of bonding the optical members to each other via the adhesive sheet disclosed herein, (2) a method of bonding the optical members to members other than the optical members via the adhesive sheet disclosed herein, and (3) a method of bonding the adhesive sheet to the optical members or members other than the optical members in a form including the optical members. In the aspect (3), the pressure-sensitive adhesive sheet in the form including an optical member may be, for example, a pressure-sensitive adhesive sheet in which the supporting substrate is an optical member (for example, an optical film). The pressure-sensitive adhesive sheet including the optical member as a support substrate in this manner can also be understood as a pressure-sensitive adhesive optical member (e.g., a pressure-sensitive adhesive optical film). The pressure-sensitive adhesive sheet disclosed herein is a type of pressure-sensitive adhesive sheet having a support substrate, and when the functional film is used as the support substrate, the pressure-sensitive adhesive sheet disclosed herein can be understood as an "adhesive type functional film" having a pressure-sensitive adhesive layer disclosed herein on at least one side of the functional film.

The adhesive sheet disclosed herein can be preferably used for application to a decorative film. The decorative film is a film having design (including character information such as color, hue, pattern, and logo) on the surface (decorative surface), and is also referred to as a design film or a decorative film. The decorative film includes a member that plays a role of decoration and protection while maintaining the visibility of the image display device and the input device. Examples of the decorative film include a film having a decorative layer (a printed layer, a laminated layer, a colored layer, a glossy layer, a continuous or discontinuous inorganic layer (a metal layer, a metal oxide layer, or the like)) for imparting a desired appearance.

The decorative film may have a decorative layer. Examples of the decorative layer include a printed layer, a laminated layer, a colored layer, a glossy layer, and a continuous or discontinuous inorganic layer that give a desired appearance. Examples of the continuous or discontinuous inorganic layer include a continuous or discontinuous metal layer, a continuous or discontinuous metal oxide layer, a laminate of a continuous or discontinuous metal layer and a metal oxide layer, a continuous or discontinuous metal/metal oxide composite layer, and the like. Examples of the metal include aluminum, zinc, lead, copper, silver, and alloys thereof. Examples of the metal oxide include chromium oxide, indium oxide, zinc oxide, and titanium oxide. The metal layer and the metal oxide layer can be formed by evaporation, sputtering, or the like. As a representative example of the decorative film, a metallic tone film is cited. The metallic-tone decorative film may have electromagnetic wave permeability in addition to metallic luster. Examples of such decorative films include electromagnetic wave-transmitting metallic luster members described in japanese patent application laid-open No. 2018-69462, japanese patent laid-open No. 2019-123238, and japanese patent laid-open No. 2019-188805.

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

In the decorative film including the decorative layer, the thickness of the decorative layer is preferably in the range of about 1 to 1000nm, for example, about 1 to 300nmThe particle size may be about 1 to 200 nm. The decorative layer preferably has a sheet resistance of 100 Ω/□ or more, for example, 250 Ω/□ or more, or 1000 Ω/□ or more. The decorative film having such a decorative layer can be a decorative film having radio wave permeability, and therefore can be preferably used for various applications requiring radio wave permeability, such as portable electronic devices. The upper limit of the sheet resistance of the decorative layer is not particularly limited, and may be, for example, 1 × 10¹⁶Omega/□ or less. The sheet resistance can be measured by an overcurrent measurement method described in JIS Z2316.

The design forming surface of the decorative film may have a flat surface, or may have a printed matter such as a logo, or unevenness due to imprinting or the like. The pressure-sensitive adhesive sheet disclosed herein may be a pressure-sensitive adhesive sheet having excellent level difference following properties, and therefore can be favorably adhered to the surface of the decorative film having the above-described irregularities.

The pressure-sensitive adhesive sheet disclosed herein is excellent in visibility for an adherend having high surface smoothness, and therefore can be preferably used for application to a transparent member and application for fixing 2 members at least one of which is a transparent member. As such a member fixing application, there is an embodiment in which one member is a transparent member and the other member is a member having an image display surface, a decorative surface, and a colored surface. In other words, the adhesive sheet disclosed herein is preferably used for fixing a member having an image display surface, a decorative surface, and a colored surface to a transparent member. Examples of the image display surface include the liquid crystal display surface, the organic EL display surface, the PDP, and the electronic paper. The decorative surface may be the decorative surface of the decorative film. The colored surface may be the surface of a light-shielding film or a masking film. As the transparent member, a member formed of a transparent material containing a resin such as glass, acrylic resin, polycarbonate, PET, or the like can be used. In such a configuration, for example, by using a pressure-sensitive adhesive sheet having a total light transmittance and a haze value of not less than predetermined values, the image display surface, the decorative surface, or the colored surface of the member to be adhered can be visually recognized satisfactorily through the pressure-sensitive adhesive sheet and the transparent member.

The transparent member may be flat and flat, but may have irregularities such as printing or embossing on the pressure-sensitive adhesive sheet-adhering surface, or may have a three-dimensional shape as a whole. The pressure-sensitive adhesive sheet disclosed herein can be a pressure-sensitive adhesive sheet having excellent level difference following properties, and therefore can be favorably adhered to the surface of a transparent member having the above-described irregularities. The transparent member having a three-dimensional shape may have a bent portion that is bent linearly or a bent portion that is bent in a curved shape in a cross section in the thickness direction. The transparent member may have a shape in which the adhesive sheet attachment surface is bent or curved in any direction, or may have a shape in which the adhesive sheet attachment surface is bent or curved in both directions, i.e., in the one direction and in a direction intersecting (e.g., orthogonal to) the one direction. In other words, the adhesive sheet attachment surface of the transparent member may have a two-dimensional structure or a three-dimensional structure.

The adhesive sheet disclosed herein can be preferably used for portable electronic devices. In the above-described portable electronic device, the present invention can be preferably used for application to a transparent member and for fixing a member at least one of which is a transparent member. In addition, the portable electronic device can be preferably used for application to an image display surface, a decorative surface, or a coloring surface. For example, the adhesive sheet disclosed herein can be preferably used for fixing an image display surface, a decorative surface, and a colored surface of a component (e.g., a decorative film) to the inside of a transparent case as a transparent member. With this configuration, the decorative surface and the like can be visually recognized from the outside of the case, and on the other hand, for example, in the case of using a member having a colored surface, the interior shielding property can be provided, and therefore, the present invention is particularly suitable as an exterior structure such as a housing.

Non-limiting examples of the portable electronic device include a mobile phone, a smart phone, a tablet personal computer, a notebook personal computer, various wearable devices (e.g., a wrist-worn type such as a wristwatch, a modular type worn on a part of the body with a clip, a band, or the like, an eye-worn (eyewear) type including a spectacle type (a single-eye type, a double-eye type, or a helmet type), a clothing type attached to a shirt, a sock, a hat, or the like in the form of an ornament, an ear-worn type such as an earphone), a digital camera, a digital video camera, an audio device (a portable music player, a recording pen, or the like), a calculator (a desktop calculator, or the like), a portable game device, an electronic dictionary, an electronic notebook, an electronic book, an in-car information device, a portable radio, a portable television, a portable printer, a portable music player, a portable music recorder, an electronic book, an in-car information device, a portable radio, a portable television, a portable printer, a portable information device, a portable information terminal, portable scanners, portable modems, and the like. It should be noted that "portable" in this specification is interpreted as being insufficient if it is merely portable, which means having a level of portability at which an individual (a standard adult) can relatively easily move.

The matters disclosed in the present specification include the following.

[ 1 ] an adhesive sheet with a release film, comprising: a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer, and a release film laminated on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet,

the maximum height Rz of the pressure-sensitive adhesive surface side surface of the release film is 400nm or less.

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

[3 ] the pressure-sensitive adhesive sheet with a release film according to the above [ 1 ] or [2 ], wherein a peeling force of the release film with respect to the pressure-sensitive adhesive sheet is 1N/50mm or less.

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

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

[ 6 ] the release film-attached pressure-sensitive adhesive sheet according to any one of [ 1 ] to [ 5 ] above, wherein the pressure-sensitive adhesive sheet is a one-sided adhesive sheet having the pressure-sensitive adhesive layer and a support substrate laminated on one surface of the pressure-sensitive adhesive layer.

[ 7 ] the pressure-sensitive adhesive sheet with a release film according to any one of [ 1 ] to [ 5 ] above, wherein the pressure-sensitive adhesive sheet is a double-sided adhesive sheet having a 1 st adhesive surface and a 2 nd adhesive surface,

the release film includes a 1 st release film disposed on the 1 st adhesive surface and a 2 nd release film disposed on the 2 nd adhesive surface,

the maximum height Rz of the 1 st adhesive surface side surface S1 of the 1 st release film₁And the maximum height Rz of the 2 nd adhesive surface side surface S2 of the 2 nd release film₂All of them are 400nm or less.

[ 8 ] the pressure-sensitive adhesive sheet with a release film according to any one of [ 1 ] to [ 5 ] above, wherein the pressure-sensitive adhesive sheet is a double-sided adhesive sheet having a 1 st adhesive surface and a 2 nd adhesive surface,

the release film is a double-sided release film having a 1 st release surface and a 2 nd release surface,

the maximum height Rz of the 1 st release surface of the release film₁And the maximum height Rz of the 2 nd release surface of the release film₂All of them are 400nm or less.

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

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

[ 11 ] the pressure-sensitive adhesive sheet with a release film according to any one of [ 1 ] to [ 10 ] above, wherein the pressure-sensitive adhesive sheet has a storage modulus at 25 ℃ of 4X 10⁴Pa or above.

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

[ 13 ] the pressure-sensitive adhesive sheet with a release film according to any one of [ 1 ] to [ 12 ] above, wherein the pressure-sensitive adhesive sheet has an elastic modulus of 3.0MPa or more as measured by the following tensile test.

[ tensile test ]

[ 14 ] the pressure-sensitive adhesive sheet with a release film according to any one of [ 1 ] to [ 13 ] above, wherein the pressure-sensitive adhesive sheet has an impact resistance of 2.0J/10mm as measured by the following shear impact test²The above.

[ shear impact test ]

[ 15 ] the pressure-sensitive adhesive sheet with a release film according to any one of [ 1 ] to [ 14 ] above, wherein the pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer containing a polymer (A) and a photoreactive monomer (B).

[ 16 ] the pressure-sensitive adhesive sheet with a release film according to [ 15 ] above, wherein the photoreactive monomer (B) comprises a compound B1 having a cyclic structure and 2 or more ethylenically unsaturated groups in the molecule, and the molecular weight of the compound B1 is 100g/mol or more per 1 ethylenically unsaturated group.

[ 17 ] the pressure-sensitive 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 a bisphenol A structure, a bisphenol F structure and a bisphenol E structure in a molecule.

[ 18 ] the pressure-sensitive adhesive sheet with a release film according to the above [ 16 ] or [ 17 ], wherein the compound B1 contains an aliphatic ring structure as the ring structure.

[ 19 ] the pressure-sensitive adhesive sheet with a release film according to any one of [ 16 ] to [ 18 ] above, wherein the compound B1 contains at least one structure selected from the group consisting of a hydroxyl group and an amino group in the molecule.

[ 20 ] the pressure-sensitive adhesive sheet with a release film according to any one of [ 16 ] to [ 19 ], wherein a content of the compound B1 in the pressure-sensitive adhesive layer is 0.5 to 60 parts by weight based on 100 parts by weight of the polymer (A).

[ 21 ] the pressure-sensitive adhesive sheet with a release film according to any one of [ 16 ] to [ 20 ] above, wherein the pressure-sensitive adhesive layer contains the compound B1 and a compound B2 having a functional group number of 2 or more and containing no ring structure in a molecule as the photoreactive monomer (B).

The pressure-sensitive adhesive sheet with a release film according to [ 21 ] above, wherein the functional group equivalent of the compound B2 is smaller than the functional group equivalent of the compound B1.

[ 23 ] the pressure-sensitive adhesive sheet with a release film according to [ 21 ] or [ 22 ] above, wherein the functional group equivalent of the compound B2 is 400g/mol or less.

[ 24 ] the pressure-sensitive adhesive sheet with a release film according to any one of [ 21 ] to [ 23 ] above, wherein the content of the compound B2 in the pressure-sensitive adhesive layer is 25 parts by weight or less based on 100 parts by weight of the polymer (A).

[25 ] the pressure-sensitive adhesive sheet with a release film according to any one of [ 15 ] to [ 24 ], wherein a content of the photoreactive monomer (B) in the pressure-sensitive adhesive layer is 1 to 80 parts by weight based on 100 parts by weight of the polymer (A).

[ 26 ] the pressure-sensitive adhesive sheet with a release film according to any one of [ 15 ] to [25 ], wherein the polymer (A) is an acrylic polymer.

[ 27 ] the pressure-sensitive adhesive sheet with a release film according to [ 26 ], wherein the monomer component constituting the acrylic polymer contains a monomer having a nitrogen atom-containing ring.

[ 28 ] the pressure-sensitive adhesive sheet with a release film according to any one of [ 15 ] to [ 27 ], wherein the polymer (A) has a glass transition temperature of-45 ℃ or more and less than 0 ℃.

The pressure-sensitive adhesive sheet with a release film according to any one of [ 15 ] to [ 28 ], wherein the pressure-sensitive adhesive layer is crosslinked with a crosslinking agent.

[ 30 ] the pressure-sensitive adhesive sheet with a release film according to any one of [ 15 ] to [ 29 ], wherein the pressure-sensitive adhesive layer contains a photopolymerization initiator.

[ 31 ] the pressure-sensitive adhesive sheet with a release film according to any one of [ 15 ] to [ 30 ], wherein the pressure-sensitive adhesive layer contains a silane coupling agent.

[ 32 ] the pressure-sensitive adhesive sheet with a release film according to any one of [ 1 ] to [ 31 ], wherein the pressure-sensitive adhesive sheet has an adhesion to glass of 1.0N/20mm or more.

[ 33 ] the pressure-sensitive adhesive sheet with a release film according to any one of [ 1 ] to [ 32 ] above, which is used for fixing a member having an image display surface, a decorative surface or a colored surface to a transparent member.

[ 34 ] A roll of pressure-sensitive adhesive sheet with release film obtained by winding the pressure-sensitive adhesive sheet with release film according to any one of [ 1 ] to [ 33 ].

Examples

The present invention will be described below with reference to some examples, but the present invention is not intended to be limited to the embodiments shown in the examples. In the following description, "part" and "%" are based on weight unless otherwise specified.

< evaluation method >

[ Total light transmittance and haze value ]

The release film on the side peeled from the pressure-sensitive adhesive sheet with the release film was bonded to a glass slide (trade name "white polished No. 1" manufactured by Sonlang Nitzzi industries Co., Ltd., thickness of 0.8 to 1.0mm, total light transmittance of 92%, haze value of 0.2%). Then, the other side of the release film was peeled off to prepare a test piece having a layer of an adhesive sheet/glass slide. The total light transmittance and haze value of the thus-obtained test piece were measured by a haze meter (device name "HM-150N", manufactured by color technical research in village). In the measurement, the glass plate to which the adhesive sheet is attached may be arranged so that the adhesive sheet is on the light source side.

[ adhesion to glass ]

The pressure-sensitive adhesive sheet with a release film was cut into a length of 100mm and a width of 20 mm. Next, the release film on one side of the release film-equipped adhesive sheet was peeled off and backed with a PET film (trade name "Lumiror S-10", manufactured by Toray corporation, thickness: 25 μm). Then, the other side (measurement surface side) of the release film was peeled off, and the peeled film was pressure-bonded to a glass plate (trade name "soda lime glass # 0050", manufactured by Sonlang Nitro industries, Ltd.) as a test plate by reciprocating a 2kg roller once to prepare a test piece composed of a test plate/adhesive sheet/PET film. The obtained test piece was autoclaved (50 ℃ C., 0.5MPa, 15 minutes) and then allowed to cool at 23 ℃ C., 50% RH for 30 minutes. After cooling, the peel strength at the time of peeling the adhesive sheet (measurement surface side) from the test plate was measured using a tensile tester (equipment name "Autograph AG-IS", Shimadzu corporation) under an atmosphere of 23 ℃ and 50% RH at a tensile rate of 300 mm/min and a peel angle of 180 ℃ in accordance with JIS Z0237. This was used as the adhesion to glass [ N/20mm ].

In the case of a pressure-sensitive adhesive sheet protected by a release film having both sides serving as release surfaces, or in the case of a one-sided adhesive pressure-sensitive adhesive sheet, the release of one release film and the backing of a PET film are not required.

[ peeling force of peeling film ]

The pressure-sensitive adhesive sheet with a release film was cut into a length of 150mm and a width of 50mm, fixed to a test plate, and the release film on the light release side was peeled from the pressure-sensitive adhesive sheet at a tensile rate of 300 mm/min and a peel angle of 180 ° under an atmosphere of 23 ℃ and 50% RH using a tensile tester (product name "Autograph AG-IS", manufactured by shimadzu corporation). The 30mm interval from the start of peeling was planed, and the maximum value of the next 50mm interval was defined as the peeling force (light peeling side) [ N/50mm ].

The peeling force of the peeling film on the heavy peeling side was determined by peeling the peeling film on the light peeling side of the pressure-sensitive adhesive sheet of the protective tape peeling film, fixing the PET film side to a test board by backing with a PET film (trade name "Lumiror S-10", manufactured by Toray corporation, thickness 25 μm), and peeling the peeling film on the heavy peeling side from the pressure-sensitive adhesive sheet at a tensile speed of 300 mm/min and a peeling angle of 180 DEG under an atmosphere of 23 ℃ and 50% RH using a tensile tester (apparatus name "Autograph AG-IS", manufactured by Shimadzu corporation). The 30mm interval from the start of peeling was planed, and the maximum value of the next 50mm interval was defined as the peeling force (heavy peeling side) [ N/50mm ] of the peeling film.

In the case of an adhesive sheet protected by a release film having both sides serving as release surfaces, or in the case of a one-sided adhesive sheet, the measurement of the release force of the release film on the light release side may be performed on one release surface in the same manner as the measurement of the release force of the release film on the light release side, and a backing of a PET film is not required.

[ arithmetic average roughness (Ra) and maximum height (Rz) ]

The arithmetic average roughness (Ra) and the maximum height (Rz) of the adhesive surface of the adhesive sheet were measured as follows. After the release film was peeled from the pressure-sensitive adhesive sheet with a release film at a peeling angle of 180 ° at a rate of 300 mm/min under the conditions for measuring the peeling force of the release film, the surface shape of the exposed pressure-sensitive adhesive surface after standing for 30 minutes was measured using a three-dimensional optical profilometer (trade name "NewView 7300", manufactured by ZYGO) under an environment of 23 ℃ and 50% RH.

The arithmetic surface roughness Ra was calculated from the data obtained by the measurement in accordance with JIS B0601-2001. The maximum height (Rz) is obtained as follows: the sum of the height Rp of the highest peak on the upper side from the average line of the roughness curve and the depth Rv of the deepest valley on the lower side from the average line is calculated for the data (roughness curve) obtained by the above measurement. The measurement conditions were as follows. Ra and Rz were measured 5 times (i.e., N is 5), and their average value was used.

(measurement conditions)

Area measurement: 5.62mm × 4.22mm

(Objective: 2.5 times, endoscope: 0.5 times)

Analysis mode:

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[ evaluation of optical distortion ]

A commercially available mirror (thickness 2mm) produced by a silver-blasting method on a plain glass plate was prepared, and no distortion was visually observed, and a reflection image was projected on a screen by a separate mirror in the same manner as described below to confirm no distortion. After removing foreign matter and the like from the surface of the mirror with clean cloth in a clean room, the release film on the side of the adhesive sheet with the release film was peeled from the adhesive sheet, adhered to the surface of the mirror with an appropriate tension so as not to mix in foreign matter, air bubbles, and deformed stripes, and subjected to defoaming treatment (treatment conditions: 50 ℃, 0.5MPa, 15 minutes) with a pressure defoaming device (autoclave) in order to remove the influence of fine air bubbles. After cooling at room temperature for 30 minutes or more, the other side release film was peeled from the adhesive sheet to prepare an optical distortion evaluation sample (a laminate composed of an adhesive sheet and a mirror). The evaluation sample was disposed so that the pressure-sensitive adhesive sheet side thereof faced the point light source side and the angle with respect to the light beam from the point light source was about 45 degrees. A white screen is provided at the front end of the light to reflect the reflected image. As the point light source, a trade name "Xenon Lamp C2577" manufactured by Hamamatsu Photonics k.k. or a product equivalent thereto can be used. The point light source, the evaluation sample, and the screen were disposed at positions where the distance from the evaluation sample to the point light source and the distance from the evaluation sample to the screen were about 50cm, respectively.

The point light source was turned on, and the image reflected by the sample and projected on the screen was visually observed, whereby the presence or absence and level of optical distortion were evaluated in the following three levels.

E: no optical distortion was observed.

A: slight optical distortion is observed, but at a practically allowable level.

P: significant optical distortion was observed.

[ elastic modulus based on tensile test ]

A test piece obtained by cutting a pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer) with a release film into a size having a width of 10mm and a length of 150mm was prepared, and the pressure-sensitive adhesive layer was exposed by peeling 2 sheets of the release film in an environment of 23 ℃ and 50% RH, and a tensile test of the test piece was performed using a tensile tester (product name "Autograph AG-IS", manufactured by shimadzu corporation) under conditions of a distance between chucks of 120mm and a tensile speed of 50 mm/min to obtain an S-S curve, and an elastic modulus [ MPa ] was calculated from an initial slope thereof (a slope in a range where an elastic deformation region of the S-S curve, specifically, a displacement IS less than about 5%).

The thickness of the test piece used in the tensile test may be the same as or different from the thickness of the pressure-sensitive adhesive sheet (typically, the pressure-sensitive adhesive layer) as described above. For example, when the thickness of the pressure-sensitive adhesive sheet is relatively small, the elastic modulus of the pressure-sensitive adhesive sheet can be determined as a result of the tensile test using a test piece prepared so that the thickness becomes 5 μm or more (for example, about 5 μm to 200 μm) for the purpose of improving the workability. The thickness of the test piece can be adjusted by appropriately laminating the pressure-sensitive adhesive layer before the irradiation of ultraviolet rays, for example, in the case of a photocurable pressure-sensitive adhesive sheet. In addition, the elastic modulus of the pressure-sensitive adhesive layer can be determined as a result of preparing a test piece having a thickness that facilitates a tensile test using the same pressure-sensitive adhesive composition as that used for forming the pressure-sensitive adhesive layer to be measured and subjecting the test piece to the tensile test. The tensile test can be carried out, for example, using a test piece having a thickness of about 10 to 50 μm (preferably about 15 to 25 μm).

[ impact resistance ]

The shear impact test was performed using a pendulum type bonding shear impact tester according to JIS K6855. As the measurement samples, the following samples were used: the pressure-sensitive adhesive sheet with a release film was cut into a 10mm square, one side of the release film was peeled off to expose the 1 st adhesive surface of the pressure-sensitive adhesive sheet, the 1 st adhesive surface was bonded to the center of a chemically strengthened glass plate (manufactured by Corning Incorporated) having a thickness of 1.7mm in a 25mm square, the other side of the release film was peeled off to expose the 2 nd adhesive surface of the pressure-sensitive adhesive sheet, the 2 nd adhesive surface was bonded to the center of a 40mm square stainless steel plate (SUS304BA plate) and pressure-bonded under a load of 5N for 10 seconds, and then autoclave treatment (50 ℃, 0.5MPa, 15 minutes) was performed at an illuminance of 300mW/cm from the glass plate side using a high-pressure mercury lamp²And a cumulative light amount of 3000mJ/cm²The conditions (2) were irradiated with ultraviolet rays, and then, aging was performed at 50 ℃ for 48 hours, thereby obtaining a sample.

The measurement sample was fixed such that the stainless steel plate was positioned on the lower side, and the energy absorption [ J ] when a hammer was applied to the outer peripheral surface of the glass plate under conditions of a hammer energy of 2.75J and a hammer velocity (impact velocity) of 3.5 m/sec was measured in an environment of 23 ℃ and 50% RH]Thus, the impact resistance [ J/10mm ] was determined²]. The measurement was performed 3 times, and the arithmetic mean of them was used.

In the case of the pressure-sensitive adhesive sheet protected by the release film having both surfaces serving as release surfaces, the measurement can be performed in the same manner as described above except that one release film is used for the release.

The pressure-sensitive adhesive sheet disclosed herein includes a pressure-sensitive adhesive in a form in which a pressure-sensitive adhesive layer is photocured after being bonded to an adherendTherefore, at least a photocurable pressure-sensitive adhesive sheet (for example, a pressure-sensitive adhesive sheet of example 4 having a pressure-sensitive adhesive C described later) was used at an illuminance of 300mW/cm²And a cumulative light amount of 3000mJ/cm²The above measurements (total light transmittance, haze value, adhesion to glass, arithmetic average roughness (Ra) and maximum height (Rz) of the adhesion surface, optical distortion evaluation, and elastic modulus by tensile test) were carried out on a measurement sample aged at 50 ℃ for 48 hours under the conditions of (1). The adhesion to glass was measured by irradiating a photocurable adhesive sheet (for example, the adhesive sheet of example 4 having the adhesive C described later) with ultraviolet light under the above-described conditions after it was pressed against a test plate. In the case where the release film is transparent, the ultraviolet irradiation treatment is preferably performed in a state where the pressure-sensitive adhesive sheet (typically, a pressure-sensitive adhesive layer) is sandwiched between transparent release films.

The illuminance/light amount of the light source is preferably measured by adjusting the actual distance between the light source and the sample using an industrial UV detector (model "UVR-T2," light receiver "UD-T36T 2," TOPCON).

< example 1 >

(preparation of adhesive composition)

After 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), 0.075 part of Irgacure651 (manufactured by BASF) and 0.075 part of Irgacure184 (manufactured by BASF) as a photopolymerization initiator were mixed together, the monomer mixture was exposed to ultraviolet light in a nitrogen atmosphere to partially polymerize the polymer, thereby obtaining a partial polymer (acrylic polymer slurry) having a polymerization rate of about 10%. To 100 parts of the obtained acrylic polymer slurry, 0.14 part of dipentaerythritol hexaacrylate (trade name "KAYARAD DPHA", manufactured by Nippon chemical Co., Ltd.) and 0.3 part of a silane coupling agent (trade name "KBM-403", manufactured by shin-Etsu chemical Co., Ltd.) were added and mixed uniformly to obtain an acrylic adhesive composition A.

(preparation of adhesive sheet)

As the 1 st release film, a release film made of PET having a thickness of 75 μm, in which the 1 st pressure-sensitive adhesive surface side surface S1, which is a surface laminated on the 1 st pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet, was a release surface formed by a silicone-based release treatment agent, and the Ra of the surface S1 was 18nm and Rz was 223nm, was prepared. As the 2 nd release film, a 100 μm thick PET release film was prepared in which the 2 nd pressure-sensitive adhesive surface side surface S2, which is a surface laminated on the 2 nd pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet, was a release surface formed by a silicone-based release treatment agent, and the Ra of the surface S2 was 18nm and Rz was 223 nm.

The obtained acrylic pressure-sensitive adhesive composition a was applied to the 1 st pressure-sensitive adhesive surface side S1 of the 1 st release film so that the thickness after the pressure-sensitive adhesive layer was formed became 100 μm to form a pressure-sensitive adhesive composition layer, and then the 2 nd release film was covered on the surface of the pressure-sensitive adhesive composition layer so that the 2 nd pressure-sensitive adhesive surface side S2 became the pressure-sensitive adhesive composition layer side. Thereby, the adhesive composition layer is shielded from oxygen. Then, the illuminance was 5mW/cm²Light quantity 2000mJ/cm²The pressure-sensitive adhesive composition layer was photo-cured by ultraviolet irradiation under the conditions described above, to produce a substrate-less double-sided pressure-sensitive adhesive sheet consisting of only an acrylic pressure-sensitive adhesive layer (also referred to as a pressure-sensitive adhesive a) and having each surface of the acrylic pressure-sensitive adhesive layer protected by a 1 st release film and a 2 nd release film. The weight average molecular weight (Mw) of the acrylic polymer as the base polymer of the pressure-sensitive adhesive layer was 200 ten thousand.

< example 2 >

As the 1 st release film and the 2 nd release film, release films having surfaces S1 and S2 having Ra and Rz shown in table 1 were used, respectively. In addition, the thickness of the adhesive layer was changed to 25 μm. Except for this, the substrate-less double-sided pressure-sensitive adhesive sheet of this example was produced in the same manner as in example 1.

< example 3 >

An acrylic polymer slurry was prepared in the same manner as in example 1 except that the monomer components were changed to 68 parts of 2-ethylhexyl acrylate (2EHA), 15 parts of N-vinyl-2-pyrrolidone (NVP), and 17 parts of HEA, and an acrylic adhesive composition B was obtained in the same manner as in example 1 except that the obtained acrylic polymer slurry was used. The substrate-less double-sided adhesive sheet of this example was prepared in the same manner as in example 2, except that the obtained acrylic adhesive composition B was used and the thickness of the adhesive layer (also referred to as adhesive B) was set to 50 μm.

< example 4 >

(preparation of adhesive composition)

In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, 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 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 for making the monomer components 45%, nitrogen gas was passed through the vessel, and nitrogen substitution was performed for about 1 hour while stirring. Then, the reaction vessel was heated to 60 ℃ to conduct a reaction for 7 hours, thereby obtaining an acrylic polymer having a weight-average molecular weight (Mw) of 35 ten thousand. To the solution of the acrylic polymer (100 parts of solid content) were added 0.1 parts of trimethylolpropane/xylylene diisocyanate adduct (trade name "Takenate D-110N", manufactured by Mitsui Chemical Co., Ltd., solid content concentration 75%) as an isocyanate-based crosslinking agent, 0.01 parts of dioctyltin dilaurate (Tokyo Fine Chemical CO., LTD., trade name "EMBILIZER OL-1") as a crosslinking accelerator, 4 parts of acetylacetone as a crosslinking retarder, 0.3 parts of 3-glycidoxypropyltrimethoxysilane (trade name "KBM-403", manufactured by shin-Etsu Chemical Co., Ltd.) as a silane coupling agent, 8 parts of dipentaerythritol hexaacrylate (trade name "A-DPH" manufactured by Nikkiso Chemical Co., Ltd.) as a photoreactive monomer, and tricyclodecane dimethanol diacrylate (manufactured by Mitsuma Chemical Co., Ltd.; Ltd., product of Mitsui Chemical Co., Ltd., product of Japan, trade name "C.," Doku Kogyo Co., Ltd., "Co., Ltd."), Trade name "A-DCP") 12 parts and 1-hydroxycyclohexyl phenyl ketone (trade name "Omnirad 184", manufactured by IGM registers) 0.7 part as a photopolymerization initiator were uniformly mixed to prepare an adhesive composition C of this example.

(preparation of adhesive sheet)

As the 1 st release film and the 2 nd release film, release films having surfaces S1 and S2 having Ra and Rz shown in table 1 were used, respectively.

The pressure-sensitive adhesive composition C obtained above was applied to the 1 st pressure-sensitive adhesive surface side surface S1 of the 1 st release film so that the dried thickness became 20 μm, and was dried by heating at 60 ℃ for 1 minute under normal pressure and at 120 ℃ for 3 minutes, and further cured at 23 ℃ for 120 hours to form a photocurable pressure-sensitive adhesive layer (substrate-less double-sided pressure-sensitive adhesive sheet). The 2 nd pressure-sensitive adhesive surface side surface S2 of the 2 nd release film was bonded to and protected by the surface of the photocurable pressure-sensitive adhesive layer. In this manner, a substrate-less double-sided adhesive sheet was prepared which consisted of only a photocurable acrylic adhesive layer (also referred to as adhesive C) and each side of the photocurable acrylic adhesive layer was protected by the 1 st release film and the 2 nd release film.

< example 5 >

As the 1 st release film and the 2 nd release film, release films having surfaces S1 and S2 having Ra and Rz shown in table 1 were used, respectively. In addition, the thickness of the adhesive layer was changed to 100 μm. Except for this, the substrate-less double-sided pressure-sensitive adhesive sheet of this example was produced in the same manner as in example 3.

< example 6 to 7 >

As the 1 st release film and the 2 nd release film, release films having surfaces S1 and S2 having Ra and Rz shown in table 1 were used, respectively. In example 6, the thickness of the pressure-sensitive adhesive layer was changed to 25 μm. Except for this, the substrate-less double-sided pressure-sensitive adhesive sheets of the respective examples were produced in the same manner as in example 1.

< evaluation >

The pressure-sensitive adhesive sheets with release films of the examples were evaluated for total light transmittance [% ], haze value [% ], glass adhesion [ N/20mm ], release force of the release film [ N/50mm ], arithmetic average roughness (Ra) nm, maximum height (Rz) nm, and optical distortion. The results are shown in Table 1. Further, the adhesive sheet of example 4 was subjected to a tensile test to measure the elastic modulus, and the adhesive sheets of examples 1 to 4 were subjected to an impact resistance test. Table 1 also shows the outline of each example (release surfaces Ra and Rz of the release film, type of adhesive, thickness [ μm ] of the pressure-sensitive adhesive sheet, storage modulus [ Pa ] at 25 ℃ and gel fraction [% ]).

[ TABLE 1 ]

TABLE 1

As shown in table 1, in examples 1 to 5, the maximum height Rz of the pressure-sensitive adhesive surface side surface of the release film was 400nm or less, and in the pressure-sensitive adhesive sheets of these examples, no optical distortion was observed after the release film was peeled, or the optical distortion was within a practically allowable range. In addition, the arithmetic average roughness Ra of the pressure-sensitive adhesive surface side surface of the release films of these examples is 30nm or less, and the peeling force of the release film is 1N/50mm or less. On the other hand, in examples 6 to 7, the maximum height Rz of the pressure-sensitive adhesive surface side surface of the release film exceeded 400nm, and unevenness was observed in the optical distortion evaluation. The adhesive sheet of example 4 had an elastic modulus of 3.0MPa or more in a tensile test, and the adhesive sheets of examples 1 to 4 all had an impact resistance of 2.0J/10mm²The above.

Specific examples of the present invention have been described above in detail, but these are merely examples and do not limit the scope of the claims. The embodiments described in the claims include various modifications and changes made to the specific examples described above.

Claims

1. A release film-equipped adhesive sheet comprising: a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer, and a release film laminated on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet,

2. The release film-equipped adhesive sheet according to claim 1, wherein the arithmetic average roughness Ra of the surface of the release film is 30nm or less.

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

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

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

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

7. The release film-equipped adhesive sheet according to any one of claims 1 to 5, wherein the adhesive sheet is a double-sided adhesive sheet having a 1 st adhesive surface and a 2 nd adhesive surface,

the maximum height Rz of the 1 st adhesive surface side surface S1 of the 1 st release film₁And a maximum height Rz of the 2 nd adhesive surface side surface S2 of the 2 nd release film₂All of them are 400nm or less.

8. The release film-equipped adhesive sheet according to any one of claims 1 to 5, wherein the adhesive sheet is a double-sided adhesive sheet having a 1 st adhesive surface and a 2 nd adhesive surface,

the peeling film is a double-sided peeling film having a 1 st peeling surface and a 2 nd peeling surface,

maximum height Rz of the 1 st release surface of the release film₁And a maximum height Rz of the 2 nd release surface of the release film₂All of them are 400nm or less.

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

10. The release film-equipped adhesive sheet according to any one of claims 1 to 9, wherein the adhesive layer has a gel fraction of 30 to 95 wt%.

11. The release film-equipped adhesive sheet according to any one of claims 1 to 10, wherein the adhesive layer has a storage modulus at 25 ℃ of 4 x 10⁴Pa or above.

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

13. The release film-equipped adhesive sheet according to any one of claims 1 to 12, wherein the adhesive sheet has an elastic modulus of 3.0MPa or more as measured by the following tensile test,

the tensile test was:

the adhesive sheet had an adhesive layer with an illuminance of 300mW/cm²And a cumulative light amount of 3000mJ/cm²The adhesive layer was cut into a size of 10mm in width and 150mm in length after curing at 50 ℃ for 48 hours under irradiation with ultraviolet rays to prepare a test piece, and a tensile test of the test piece was carried out under an environment of 23 ℃ and 50% RH at a chuck-to-chuck distance of 120mm and a tensile speed of 50 mm/minute using a tensile tester to obtain a stress-displacement curve, and the elastic modulus [ MPa ] was calculated from the initial slope thereof]。

14. The release film-equipped adhesive sheet according to any one of claims 1 to 13, wherein the adhesive sheet has an impact resistance of 2.0J/10mm as measured by the shear impact test²In the above-mentioned manner,

the shear impact test is as follows:

a shear impact test was performed using a pendulum type bonding shear impact tester based on JIS K6855; as the measurement samples, the following samples were used: bonding a first surface of the adhesive sheet of 10mm square to a center portion of a chemically strengthened glass plate of 25mm square and 1.7mm thickness, bonding a second surface of the adhesive sheet to a center portion of a stainless steel plate of 40mm square, and pressure-bonding under a load of 5N for 10 seconds, followed by autoclave treatment at 50 ℃ and 0.5MPa for 15 minutes from the glass plate side with illuminance of 300mW/cm²And a cumulative light amount of 3000mJ/cm²The conditions of (1) irradiating ultraviolet rays, and then, aging at 50 ℃ for 48 hours, thereby obtaining a sample, the stainless steel plate being a SUS304BA plate;

the measurement sample was fixed so that the stainless steel plate was positioned on the lower side, and the absorption energy [ J ] when a hammer was hit against the outer peripheral surface of the glass plate under conditions of a hammer energy of 2.75J and a hammer speed of 3.5 m/sec was measured at 23 ℃ and 50% RH]Thus, the impact resistance [ J/10mm ] was determined²]。

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

16. The adhesive sheet with a release film according to claim 15, wherein the photoreactive monomer (B) comprises a compound having a ring structure and 2 or more ethylenically unsaturated groups in a molecule, and the molecular weight of the compound B1 is 100g/mol or more per 1 ethylenically unsaturated group.

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

18. A release film-equipped adhesive sheet roll obtained by winding the release film-equipped adhesive sheet according to any one of claims 1 to 17.