CN107033793B - Adhesive sheet and adhesive sheet with release film - Google Patents

Abstract

The present invention relates to an adhesive sheet and an adhesive sheet with a release film. The invention provides an adhesive sheet comprising an adhesive layer. The adhesive sheet has a first side and a second side. The first surface is a first adhesive surface formed of one surface of the adhesive layer. The first adhesive surface has a ten-point average roughness of 1000nm or less. The adhesive layer has a storage modulus at 100 ℃ of 0.08MPa or more.

Description

Adhesive sheet and adhesive sheet with release film

Technical Field

This application claims priority based on Japanese patent application 2015-232149, filed on 27/11/2015 and Japanese patent application 2016-139538, filed on 14/2016, which are incorporated herein by reference in their entirety.

The present invention relates to an adhesive sheet and an adhesive sheet with a release film.

Background

In general, an adhesive (also referred to as a pressure-sensitive adhesive hereinafter) is in a soft solid (viscoelastic material) state in a temperature range around room temperature, and has a property of being easily adhered to an adherend by pressure. In view of the above properties, adhesives are widely used in various industrial fields such as home electric appliances, automobiles, Office Automation (OA) equipment, and the like, typically in the form of an adhesive sheet including a layer containing the adhesive.

In the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive surface (surface of the pressure-sensitive adhesive layer) is required to have high smoothness. As an example of such a pressure-sensitive adhesive sheet, a pressure-sensitive adhesive sheet for optical use is cited.

As a technical document relating to prevention of generation of unevenness on the surface of an adhesive layer, japanese patent application laid-open No. 2014-189778 is cited. International publication No. 2014/156335 is a technical document relating to a double-sided pressure-sensitive adhesive sheet having a release film with high surface smoothness.

Disclosure of Invention

In general, from the viewpoint of ease of distribution and productivity, pressure-sensitive adhesive sheets (particularly industrial pressure-sensitive adhesive sheets) are often produced in the form of a long tape-like pressure-sensitive adhesive sheet wound in a spiral or in the form of a sheet having a large area. Thereafter, the pressure-sensitive adhesive sheet may be subjected to various processes or treatments before finally being affixed to the respective adherends. Examples of the processing or treatment include processing for fitting the outer shape of the pressure-sensitive adhesive sheet to the shape of the adherend by punching, cutting, or the like, and processing for preparing the pressure-sensitive adhesive sheet into a form suitable for enhancing the efficiency and accuracy of the operation of attaching the pressure-sensitive adhesive sheet to the adherend.

In the course of such processing or treatment, a release film for protecting the adhesive surface of the adhesive sheet may be replaced. That is, one release film may be removed from the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet, and the release surface of another release film may be bonded to the exposed pressure-sensitive adhesive surface. Therefore, the release film present on the adhesive surface of the pressure-sensitive adhesive sheet immediately before the pressure-sensitive adhesive sheet is attached to the adherend may be a release film different from the release film present on the adhesive surface at the time of initially manufacturing the pressure-sensitive adhesive sheet. With the recent diversification, miniaturization, large screen size, improvement in appearance, and the like of optical products, there is a tendency that the timing of replacing the release film on the pressure-sensitive adhesive surface and the necessity thereof are increased until the pressure-sensitive adhesive sheet to be produced is adhered to an adherend. However, as described above, since the pressure-sensitive adhesive is a viscoelastic body, even if the pressure-sensitive adhesive sheet is initially produced so as to have a highly smooth pressure-sensitive adhesive surface, the smoothness of the pressure-sensitive adhesive surface is reduced (roughened) by subsequent processing. For example, when a release film for protecting a highly smooth pressure-sensitive adhesive surface is replaced with another release film, the smoothness of the pressure-sensitive adhesive surface may be reduced by the replacement release film.

Accordingly, an object of the present invention is to provide an adhesive sheet having a highly smooth adhesive surface, the smoothness of which is not easily impaired. Another object of the present invention is to provide a release film-equipped pressure-sensitive adhesive sheet having a release film on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet.

The inventors of the present invention found that: the present inventors have found that the above problems can be solved by focusing attention on the storage modulus at 100 ℃ (storage modulus at 100 ℃) of the pressure-sensitive adhesive layer constituting the highly smooth pressure-sensitive adhesive surface, and thus have completed the present invention.

According to the present specification, an adhesive sheet comprising an adhesive layer is provided. The adhesive sheet has a first side and a second side. The first surface is a first adhesive surface formed of one surface of the adhesive layer. A ten-point average roughness (Rz) of the first adhesive surface_A1) About 1000nm or less. Storage modulus at 100 ℃ (G ') of the adhesive layer'₁₀₀) Is about 0.08MPa or more. The adhesive sheet has a highly smooth first adhesive surface and G 'of an adhesive layer constituting the first adhesive surface'₁₀₀Therefore, the smoothness of the first adhesive surface tends not to be easily impaired. Therefore, the pressure-sensitive adhesive sheet is suitable for applications (for example, optical applications) requiring a highly smooth pressure-sensitive adhesive surface.

In one embodiment of the technology disclosed herein, the adhesive layer has a storage modulus at 100 ℃ (G'₁₀₀) Is the storage modulus at 23 ℃ of the adhesive layer (storage modulus at 23 ℃; g'₂₃) About 35% or more. Namely, the storage modulus ratio (G ') at 100 ℃/23 ℃ of the pressure-sensitive adhesive layer'₁₀₀/G'₂₃) About 35% or more. When the pressure-sensitive adhesive sheet having such a pressure-sensitive adhesive layer is used, the performance of maintaining the smoothness of the first pressure-sensitive adhesive surface and the workability of application at room temperature tend to be suitably compatible with each other. G'₁₀₀/G'₂₃The upper limit of (b) is not particularly limited, but is usually about 100% or less.

In one embodiment of the technology disclosed herein, the adhesive layer has a storage modulus (G ') at 23 ℃'₂₃) Less than about 0.30 MPa. The pressure-sensitive adhesive sheet having such a pressure-sensitive adhesive layer tends to exhibit good initial adhesiveness at room temperature.

In one embodiment of the technology disclosed herein, the second surface of the adhesive sheet is a second adhesive surface. That is, the pressure-sensitive adhesive sheet of this embodiment is configured as a double-sided pressure-sensitive adhesive sheet in which both the first side and the second side are pressure-sensitive adhesive surfaces. Such a double-sided adhesive sheet can be preferably used for purposes such as joining, fixing, and the like of members. In one embodiment, the second adhesive surface has a ten-point average roughness (Rz)_A2) And may be about 2000nm or less (preferably about 1000nm or less). The double-sided adhesive sheet having such a second adhesive surface is suitable for applications requiring a highly smooth adhesive surface.

In one embodiment of the technology disclosed herein, the second surface may be a second adhesive surface formed of the other surface of the adhesive layer. That is, one surface and the other surface of the adhesive layer constitute a first adhesive surface and a second adhesive surface of the adhesive sheet, respectively. The pressure-sensitive adhesive sheet of this embodiment has a simple structure, and is therefore suitable for improving optical characteristics (e.g., transparency). In one embodiment, the second adhesive surface of the second adhesive surface has a ten-point average roughness (Rz)_A2) And may be about 2000nm or less (e.g., about 1000nm or less). The adhesive sheet has a highly smooth second adhesive surface and is G 'of the adhesive layer constituting the second adhesive surface'₁₀₀Therefore, the smoothness of the second surface tends not to be easily impaired. And thus is suitable for applications requiring a highly smooth adhesive surface.

According to the present specification, there is also provided a release film-equipped adhesive sheet comprising any of the adhesive sheets disclosed herein and a first release film disposed on the first adhesive surface of the adhesive sheet. The pressure-sensitive adhesive sheet constituting such a release film-equipped pressure-sensitive adhesive sheet can be suitably used in a form of being attached to an adherend through a process of replacing (pasting) the first release film with another release film as desired.

In this manner, the release film-equipped pressure-sensitive adhesive sheet having the first release film on the first pressure-sensitive adhesive surface is preferably a ten-point average roughness (Rz) of the release surface of the first release film in contact with the first pressure-sensitive adhesive surface_R1) A ten-point average roughness (Rz) of the first adhesive surface_A1) The difference is within 250 nm. I.e., | Rz_R1-Rz_A1| is preferably 250nm or less. In such a release film-equipped pressure-sensitive adhesive sheet, the release surface of the first release film has good adhesion to the first pressure-sensitive adhesive surface, and therefore the pressure-sensitive adhesive sheet tends to have excellent appearance quality. Hereinafter, the release surface in contact with the first pressure-sensitive adhesive surface may be referred to as a "first release surface". The release surface in contact with the second adhesive surface may be referred to as a "second release surface".

According to the present specification, there is also provided a release-coated adhesive sheet comprising any of the double-sided adhesive sheets disclosed herein, a first release film disposed on the first adhesive side of the adhesive sheet, and a second release film disposed on the second adhesive side of the adhesive sheet. The double-sided pressure-sensitive adhesive sheet constituting such a release film-equipped pressure-sensitive adhesive sheet can be suitably used in a form of being attached to an adherend through a process of replacing one or both of the first release film and the second release film with another release film as desired.

In this manner, the release film-attached pressure-sensitive adhesive sheet (release film-attached double-sided pressure-sensitive adhesive sheet) including the double-sided pressure-sensitive adhesive sheet, the first release film, and the second release film may be, in a preferred embodiment: a ten-point average roughness (Rz) of the first release surface of the first release film_R1) A ten-point average roughness (Rz) of the first adhesive surface_A1) The difference between the first and second release films is 250nm or less, and the second release surface of the second release film has a ten-point average roughness (Rz)_R2) A ten-point average roughness (Rz) of the second adhesive surface_A2) The difference is within 250 nm. That is, | Rz can be_R1-Rz_A1| is 250nm or less and | Rz_R2-Rz_A2And | is within 250 nm. In the release film-equipped pressure-sensitive adhesive sheet of the above-described aspect, the adhesiveness between the release surface of the first release film and the first pressure-sensitive adhesive surface and the adhesiveness between the release surface of the second release film and the second pressure-sensitive adhesive surface are both good, and therefore, the pressure-sensitive adhesive sheet tends to have excellent appearance quality.

Drawings

Fig. 1 is a schematic cross-sectional view showing a pressure-sensitive adhesive sheet with a release film including a pressure-sensitive adhesive sheet (double-sided pressure-sensitive adhesive sheet without a substrate) according to an embodiment.

Fig. 2 is a schematic cross-sectional view showing a pressure-sensitive adhesive sheet with a release film including a pressure-sensitive adhesive sheet (single-sided pressure-sensitive adhesive sheet with a substrate) according to another embodiment.

Description of the reference numerals

1,2 adhesive sheet

1A first side (first adhesive side)

1B second side (second adhesive side)

2A first side (first adhesive side)

2B second side (non-adhesive side)

11 adhesive layer

11A one surface

11B another surface

15 supporting the substrate

15A first side

15B second side

21 first Release film

21A surface (first stripping surface)

21B back surface

22 second Release film

22A surface (second stripping surface)

100, 200 PRESSURE-SENSITIVE ADHESIVE SHEET WITH RELEASE FILM

Detailed Description

Suitable embodiments of the present invention are described below. It is to be noted that matters necessary for carrying out the present invention other than the matters specifically mentioned in the present specification can be understood by those skilled in the art based on the teaching of the practice of the invention described in the present specification and the common general knowledge at the time of application. The present invention can be implemented based on the contents disclosed in the present specification and the common general knowledge in the art. In the drawings, members and portions that exhibit the same functions are sometimes described with the same reference numerals, and redundant description may be omitted or simplified. The embodiments shown in the drawings are illustrated for clarity of the present invention, and do not necessarily show the size or scale of the product actually provided.

This specificationThe "pressure-sensitive adhesive" is a material that exhibits a soft solid (viscoelastic material) state in a temperature range around room temperature and has a property of easily adhering to an adherend by pressure as described above. As used herein, an adhesive such as "c.a. dahlquist," bonding: basis and Practice ("Adhesion: Fundamental and Practice"), McLaren&Sons, (1966) P.143 ", generally speaking, can be a compound having a complex tensile modulus E (1Hz)<107dyne/cm²A material having the above properties (typically, a material having the above properties at 25 ℃).

The "pressure-sensitive adhesive surface" in the present specification means a surface having a peel strength of 0.1N/20mm or more when peeled in a 180-degree direction at a tensile rate of 300 mm/min after 30 minutes by using a SUS304 stainless steel plate as an adherend and reciprocating a 2kg roller 1 time under a measurement environment of 23 ℃ to pressure-bond the adherend based on JIS Z0237 (2004). The term "non-adhesive surface" as used herein means a surface not belonging to the adhesive surface, and typically means a surface having a peel strength of less than 0.1N/20 mm. A surface which is not stuck to a SUS304 stainless steel plate (a surface which does not substantially show adhesiveness) when the roll of 2kg is pressed against the stainless steel plate by reciprocating 1 time under a measurement environment of 23 ℃ is a typical example included in the concept of the non-sticking surface mentioned here.

< adhesive sheet >

The adhesive sheet disclosed herein is formed into a sheet shape having a first side and a second side (meaning including a strip-like shape of equal length). The adhesive sheet includes at least an adhesive layer. The pressure-sensitive adhesive sheet disclosed herein may be composed of only the pressure-sensitive adhesive layer, or may include components other than the pressure-sensitive adhesive layer.

The first surface of the adhesive sheet disclosed herein is an adhesive surface (first adhesive surface) constituted by one surface of the adhesive layer. The second surface of the pressure-sensitive adhesive sheet may be an adhesive surface or a non-adhesive surface. In one embodiment, the second surface of the psa sheet is a psa surface (second psa surface) formed by the other surface of the psa layer. That is, one surface and the other surface of one adhesive layer constitute a first adhesive face and a second adhesive face of the adhesive sheet, respectively. Fig. 1 shows an example of the structure of the psa sheet of this embodiment.

The adhesive sheet 1 shown in fig. 1 is a substrate-less double-sided adhesive sheet including an adhesive layer 11. The first side 1A of the adhesive sheet 1 is a first adhesive side constituted by one surface 11A of the adhesive layer 11, and the second side 1B of the adhesive sheet 1 is a second adhesive side constituted by the other surface 11B of the adhesive layer 11. The adhesive layer 11 may have a single-layer structure, or may have a multilayer structure including 2 or more sub-adhesive layers. The sub adhesive layers constituting the multilayer structure may have the same or different structures (materials, thicknesses, etc.). From the viewpoint of productivity and transparency, a mode in which the pressure-sensitive adhesive layer 11 has a single-layer structure is preferably employed.

Here, the substrate-less double-sided adhesive sheet refers to a double-sided adhesive sheet that does not include a non-releasable support substrate between the first adhesive surface and the second adhesive surface. The support substrate is a substrate that can independently maintain its shape. In addition, the non-releasable support substrate refers to a support substrate that is not intended to be separated from the adhesive layer during use of the adhesive sheet including the support substrate.

For example, as shown in fig. 1, the psa sheet 1 before use (i.e., before being adhered to an adherend) may be in a form in which the first adhesive surface 1A and the second adhesive surface 1B are protected by the first release film 21 and the second release film 22, respectively. Both the surface 21A of the first release film 21 in contact with the first adhesive surface 11A and the surface 22A of the second release film 22 in contact with the second adhesive surface 11B are release surfaces (releasable surfaces, i.e., surfaces from which the adhesive layer can be released). The psa sheet 1 of this embodiment can also be understood as a component of a release-film-attached psa sheet (release-film-attached double-sided psa sheet) 100 that includes the psa sheet 1, a first release film 21 disposed such that a surface (first release surface) 21A contacts the first psa surface 11A, and a second release film 22 disposed such that a surface (second release surface) 22A contacts the second psa surface 12A. The pressure-sensitive adhesive sheet with a release film 100 may be spirally wound. As another embodiment of the psa sheet 1 before use, the following embodiments may be exemplified: the release film 22 shown in fig. 1 is omitted, and the release film 21 having both the front surface 21A and the back surface 21B is stacked on the pressure-sensitive adhesive sheet 1 and spirally wound, so that the second pressure-sensitive adhesive surface 11B is in contact with the back surface 21B of the release film 21.

Fig. 2 shows an example of the configuration of an adhesive sheet having a non-adhesive surface as a second surface. The pressure-sensitive adhesive sheet 2 shown in fig. 2 is configured as a substrate-attached one-sided pressure-sensitive adhesive sheet including a support substrate 15 having a first surface 15A and a pressure-sensitive adhesive layer 11 disposed on the first surface 15A of the support substrate 15. Here, the first surface 15A of the support base 15 is a non-peelable surface which is a non-peelable surface. The first side 2A of the adhesive sheet 2 is a first adhesive side constituted by one surface 11A of the adhesive layer 11, and the second side 2B of the adhesive sheet 2 is a non-adhesive side constituted by the second side 15B of the support substrate 15. The second surface 15B may be a release surface or a non-release surface.

For example, as shown in fig. 2, the psa sheet 2 before use may be in a form in which the first pressure-sensitive adhesive surface 11A is protected by a first release film 21. The psa sheet 2 of this embodiment can be understood as a component of a release film-attached psa sheet (release film-attached single-sided psa sheet) 200 including the psa sheet 2 and a first release film 21 disposed so that the surface (first release surface) 21A is in contact with the first psa surface 11A. The pressure-sensitive adhesive sheet with release film 200 may be spirally wound.

Examples of other configurations of the pressure-sensitive adhesive sheet disclosed herein include: the double-sided pressure-sensitive adhesive sheet with a base material is provided with a support base material having a first surface and a second surface both of which are non-peelable, wherein the first surface of the support base material is provided with a first pressure-sensitive adhesive layer, and the second surface of the support base material is provided with a second pressure-sensitive adhesive layer. In the double-sided pressure-sensitive adhesive sheet with a substrate, the first surface of the double-sided pressure-sensitive adhesive sheet is a first pressure-sensitive adhesive surface constituted by the surface of the first pressure-sensitive adhesive layer, and the second surface of the double-sided pressure-sensitive adhesive sheet is a second pressure-sensitive adhesive surface constituted by the surface of the second pressure-sensitive adhesive layer. The composition and constitution of the first adhesive layer and the second adhesive layer may be the same, and one or both of the composition and constitution may be different. As an example of the mode in which the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer have the same composition and have different structures, there is a mode in which the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are pressure-sensitive adhesive layers having different thicknesses and composed of pressure-sensitive adhesive compositions having the same composition. The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may each independently have a single-layer structure, or may have a multilayer structure including 2 or more sub-pressure-sensitive adhesive layers. From the viewpoint of productivity and transparency, a mode in which both the first adhesive layer and the second adhesive layer have a single-layer structure is preferably employed.

The double-sided psa sheet with a substrate before use may be in the form of a first psa surface (the surface of the first psa layer) and a second psa surface protected by a first release film and a second release film, respectively, as in the double-sided psa sheet without a substrate 1 shown in fig. 1. The double-sided pressure-sensitive adhesive sheet with a substrate in this form is understood to be a constituent element of a release film-equipped pressure-sensitive adhesive sheet including the pressure-sensitive adhesive sheet, a first release film and a second release film. The pressure-sensitive adhesive sheet with a release film may be in a spirally wound form. The double-sided pressure-sensitive adhesive sheet with a substrate before use may be in a form in which a release film having a release surface on both sides is laminated on the pressure-sensitive adhesive sheet and spirally wound.

The pressure-sensitive adhesive sheet in the form including a support substrate, such as the substrate-attached single-sided pressure-sensitive adhesive sheet and the substrate-attached double-sided pressure-sensitive adhesive sheet, is not particularly limited in the material of the support substrate. Examples of the supporting substrate include plastic films, paper, woven fabrics, nonwoven fabrics, rubber sheets, foam sheets, metal foils, glass, and composites thereof. The surface of the supporting substrate on which the pressure-sensitive adhesive layer is provided may be subjected to surface treatment such as coating with a primer, corona discharge treatment, or plasma treatment. In the present specification, the plastic film is typically a non-porous sheet, and is a concept different from, for example, a nonwoven fabric (i.e., a concept not including a nonwoven fabric).

In one embodiment, various plastic films can be preferably used as the support base material for the reason of easily achieving a highly smooth first adhesive surface. Examples of the material of the plastic film include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, cellulose resins such as triacetylcellulose, acetate resins, polysulfone resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, cyclic polyolefin resins (norbornene resins, etc.), (meth) acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl alcohol resins, polyarylate resins, polyphenylene sulfide resins, and mixtures thereof. Among them, preferable materials include polyester resins, cellulose resins, polyimide resins, and polyether sulfone resins. The plastic film used as the support substrate may contain known additives in the same manner as the plastic film for releasing the film substrate described later. A transparent plastic film is preferable.

The thickness of the support base is not particularly limited and may be appropriately selected according to the purpose. In one embodiment, the support substrate may have a thickness of from about 10 μm to about 500 μm, and typically suitably from about 10 μm to about 300 μm. In one embodiment, a support substrate (e.g., the transparent plastic film described above) having a thickness of about 15 μm to about 200 μm may be preferably used.

(ten point roughness average)

The adhesive sheet disclosed herein preferably has a ten-point average roughness (Rz) of the first adhesive surface_A1) About 1000nm or less. The pressure-sensitive adhesive sheet having such a first pressure-sensitive adhesive surface is suitable for applications requiring a highly smooth pressure-sensitive adhesive surface. For example, the first adhesive surface may be preferably used so as to be stuck to the optical member. Rz from the viewpoint of providing a more smooth adhesive surface_A1It may be preferably about 700nm or less, more preferably about 500nm or less, and further preferably about 300nm or less (e.g., about 200nm or less). Rz_A1The lower limit of (b) is not particularly limited. In one embodiment, Rz can be_A1Is set to about 30nm or more (e.g., about 50nm or more).

Here, the ten-point average roughness in the present specification means a ten-point average roughness obtained by using a noncontact surface roughness measurement device unless otherwise specified. As the noncontact surface roughness measuring device, a surface roughness measuring device of an optical interference system is used. As a specific measuring apparatus, Wyko NT-9 manufactured by Veeco corporation can be used₁₀₀Or an equivalent thereof. Specific measurement procedures and measurement conditions may be carried out as described belowThe measurement conditions described in the examples, or the results obtained are set to be equivalent to or corresponding to the case of the measurement conditions. The ten-point average roughness is an average value of absolute values of differences between Yp1 to Yp10 and Yv1 to Yv10, which are obtained by measuring the elevations of the peaks from the highest peak to the 10 th position (Yp1 to Yp10) and the elevations of the valleys from the lowest valley to the 10 th position (Yv1 to Yv10) in a roughness curve obtained by the surface roughness measurement.

In the case where the psa sheet disclosed herein is in the form of a double-sided psa sheet (i.e., a psa sheet having a first psa surface and a second psa surface), the ten-point average roughness (Rz) of the second psa surface_A2) There is no particular limitation. In a preferred mode, Rz_A2It is set to about 2000nm or less (typically about 1000nm or less, preferably about 700nm or less, more preferably about 500nm or less, still more preferably about 300nm or less, for example, about 200nm or less). Rz_A2The lower limit of (b) is not particularly limited. In one embodiment, Rz can be_A2Is set to about 30nm or more (e.g., about 50nm or more). The second adhesive surface may be the other surface of the adhesive layer of which one surface constitutes the first adhesive surface, or may be a surface of an adhesive layer different from the adhesive layer constituting the first adhesive layer.

(storage modulus)

The adhesive sheet disclosed herein preferably has a storage modulus at 100 ℃ (G ') of the adhesive layer constituting the first adhesive surface'₁₀₀) Is about 0.08MPa or more. The adhesive sheet having such an adhesive layer is less likely to lose the smoothness of the first adhesive surface after the production of the adhesive sheet. For example, even if the release film on the first pressure-sensitive adhesive surface is replaced with a release film having a lower smoothness during the period from the time when the pressure-sensitive adhesive sheet is produced to the time when the pressure-sensitive adhesive sheet is attached to the adherend, the decrease in smoothness of the first pressure-sensitive adhesive surface tends to be suppressed. This is believed to be due to: when the deformation of the pressure-sensitive adhesive layer after the peeling of the film of the temporarily produced pressure-sensitive adhesive sheet is performed at a low speed, the behavior of the pressure-sensitive adhesive layer against the low-speed plastic deformation can be appropriately grasped from the 100 ℃ storage modulus of the pressure-sensitive adhesive layer (time-temperature conversion method), and the 100 ℃ storage modulus is usedThe amount is set to a predetermined value or more, and it is possible to effectively realize an adhesive sheet in which the smoothness of the first adhesive surface is not easily degraded by replacing the release film.

Of the techniques disclosed herein, G'₁₀₀May be about 0.09MPa or more, may be about 0.10MPa or more, or may be about 0.11MPa or more (for example, about 0.12MPa or more). By increasing G'₁₀₀The smoothness of the first adhesive surface tends to be maintained more favorably. The upper limit of G'100 is not particularly limited, and may be, for example, about 1.5MPa or less (typically about 1.0MPa or less). G 'from the viewpoint of adhesion to an adherend, etc'₁₀₀Generally, less than about 0.50MPa is suitable, preferably less than about 0.40MPa, more preferably less than about 0.30 MPa. G'₁₀₀The composition of the adhesive layer (for example, the composition, molecular weight, crosslinking mode, crosslinking density, whether or not an additive is used and the amount used in the case of using the additive), production method, and the like can be adjusted.

In one embodiment of the technology disclosed herein, the adhesive layer constituting the first adhesive surface of the adhesive sheet may have a storage modulus (G') at 23 ℃.₂₃) Is set to less than about 0.30 MPa. A pressure-sensitive adhesive sheet having such a pressure-sensitive adhesive layer tends to exhibit good initial adhesiveness to an adherend at room temperature. This is preferable from the viewpoint of workability (e.g., handling efficiency and joining accuracy) of joining the pressure-sensitive adhesive sheet. In one embodiment, G'₂₃It may be about 0.29MPa or less, about 0.27MPa or less, or about 0.25MPa or less. By reducing G'₂₃The initial adhesiveness of the pressure-sensitive adhesive sheet tends to be improved. G'₂₃The lower limit of (B) is not particularly limited, and may be, for example, about 0.05MPa or more. From the viewpoint of easily satisfying G '100 of a predetermined level or more, usually G'₂₃It is preferably about 0.08MPa or more, more preferably about 0.10MPa or more, and still more preferably about 0.15MPa or more (for example, about 0.17MPa or more). G'₂₃May be adjusted by the composition of the adhesive layer, the manufacturing method, and the like.

In the technique disclosed herein, the storage modulus (G ') at 100 ℃ as the adhesive layer'₁₀₀) And storage modulus at 23 ℃ (G'₂₃) Can use the constitutionThe values of storage modulus at 100 ℃ and 23 ℃ obtained by dynamic viscoelasticity measurement of the adhesive layer. As a specific measurement device, ARES manufactured by TA Instruments co., ltd., or its equivalent 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 may be set so as to obtain results equivalent to or corresponding to the case where the measurement conditions are used.

The technique disclosed herein may be applied in accordance with the 100 ℃/23 ℃ storage modulus ratio (G 'of the adhesive layer constituting the first adhesive surface'₁₀₀/G'₂₃) More than about 30% (e.g., about 31% or more) is preferably performed. G 'from the viewpoint of more suitably satisfying both of the performance of maintaining the smoothness of the first adhesive surface and the pasting workability at room temperature'₁₀₀/G'₂₃The content may be about 35% or more, about 40% or more, or about 50% or more (e.g., about 55% or more). G'₁₀₀/G'₂₃The upper limit of (b) is not particularly limited, but is usually about 100% or less, typically less than about 100%. G 'from the viewpoint of further improving the pasting workability at room temperature'₁₀₀/G'₂₃May be about 90% or less, or may be about 80% or less (e.g., about 70% or less). In one embodiment, G'₁₀₀/G'₂₃Can be set to about 35% to about 50%. Such an adhesive layer tends to easily form a highly smooth first adhesive surface.

In one embodiment of the technology disclosed herein, the adhesive layer constituting the first adhesive surface has a storage modulus at 100 ℃ (G'₁₀₀) Thickness (T) of the adhesive layer_A1) The ratio of (A) to (B) may be about 9MPa/mm or less. Has G 'like this'₁₀₀/T_A1A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer of not more than a predetermined value and G'₁₀₀/T_A1A larger pressure-sensitive adhesive layer is preferable because it tends to exhibit good adhesion for a longer period of time. For example, if G 'is used'₁₀₀Is about 0.08MPa or more (typically about 0.08MPa or more and less than about 0.50MPa) and G'₁₀₀/T_A1An adhesive layer of about 9MPa/mm or less, the following adhesive sheet can be realized: even if the release film on the first pressure-sensitive adhesive surface is replaced with a release film having a lower smoothnessThe release film is less likely to deteriorate the smoothness of the first pressure-sensitive adhesive surface and has excellent long-term adhesion to an adherend. In one embodiment, G 'may be substituted for'₁₀₀/T_A1Is set to about 7.0MPa/mm or less. The techniques disclosed herein may be followed, for example, as G'₁₀₀/T_A1Preferably about 5.0MPa/mm or less (e.g., about 3.0MPa/mm or less). G'₁₀₀/T_A1The lower limit of (B) is not particularly limited, but is preferably about 0.1MPa/mm or more.

In the technique disclosed herein, the thickness (T) of the adhesive layer constituting the first adhesive surface_A1) There is no particular limitation. T is_A1And may be, for example, from about 1 μm to about 500 μm (typically from about 1 μm to about 250 μm). In one mode T_A1It may be about 5 μm or more, or about 15 μm or more. If T_A1When the thickness is large, the smoothness of the first pressure-sensitive adhesive surface tends to be easily reduced by replacing the release film on the first pressure-sensitive adhesive surface with a release film having low smoothness. Therefore, it is more important to apply the technique disclosed herein to suppress the reduction in smoothness of the first pressure-sensitive adhesive surface. From this point of view, the techniques disclosed herein may be in terms of T_A1More than about 20 μm (more preferably about 25 μm or more, further preferably about 30 μm or more, for example about 40 μm or more) is preferably used. In addition, if T_A1When the thickness of the pressure-sensitive adhesive sheet is small, the smoothness of the first pressure-sensitive adhesive surface tends to largely affect the properties of the pressure-sensitive adhesive sheet as a whole. From this point of view, the techniques disclosed herein may be in terms of T_A1Preferably about 250 μm or less (more preferably about 150 μm or less, for example about 100 μm or less). In one mode T_A1It may be about 60 μm or less (e.g., about 50 μm or less).

In one embodiment of the technology disclosed herein, the adhesive layer constituting the first adhesive surface has a storage modulus (G ') at 23 ℃'₂₃) Thickness (T) of the adhesive layer_A1) The ratio of (A)/(B) may be less than about 10 MPa/mm. And with greater G'₂₃/T_A1Has G 'as compared with the pressure-sensitive adhesive layer'₂₃/T_A1The pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer of less than a predetermined value has a pressure-sensitive adhesive strength to an adherendThe initial adhesiveness tends to be better. For example, if G 'is used'₁₀₀Is about 0.08MPa or more (typically about 0.08MPa or more and less than about 0.50MPa) and G'₂₃/T_A1A pressure-sensitive adhesive layer of less than about 10MPa/mm makes it possible to realize a pressure-sensitive adhesive sheet in which the smoothness of the first pressure-sensitive adhesive surface is not easily impaired and the initial adhesiveness to an adherend is good even when the release film on the first pressure-sensitive adhesive surface is replaced with a release film having a lower smoothness. In one embodiment, G 'is used from the viewpoint of obtaining a more preferable effect'₂₃/T_A1Can be set to about 8.0MPa/mm or less. The techniques disclosed herein may be followed, for example, as G'₂₃/T_A1Preferably about 6.0MPa/mm or less (e.g., about 5.0MPa/mm or less). G'₂₃/T_A1The lower limit of (B) is not particularly limited, but is preferably about 0.2MPa/mm or more.

In the case where the pressure-sensitive adhesive sheet disclosed herein is in the form of a double-sided pressure-sensitive adhesive sheet, the second pressure-sensitive adhesive surface may be the other surface of the pressure-sensitive adhesive layer constituting the first pressure-sensitive adhesive surface. The double-sided adhesive sheet (substrate-less double-sided adhesive sheet) of this type has a simple structure and is therefore suitable for improving optical characteristics (e.g., transparency). The second pressure-sensitive adhesive surface may be a surface of a second pressure-sensitive adhesive layer which is a pressure-sensitive adhesive layer different from the pressure-sensitive adhesive layer constituting the first pressure-sensitive adhesive surface. The double-sided adhesive sheet of this embodiment is typically in the form of a double-sided adhesive sheet with a substrate, and various performances can be realized depending on the composition and composition of the first adhesive layer and the second adhesive layer, the combination of the compositions, and the selection of the support substrate. In one embodiment, the second pressure-sensitive adhesive layer may satisfy the above-described various properties (for example, G'₁₀₀、G'₂₃、G'₁₀₀/G'₂₃、T_A1、G'₁₀₀/T_A1、G'₂₃/T_A1Haze value, etc.) of the same or more than 1 kind or 2 kinds.

< adhesive >

In the technique disclosed herein, the type of the adhesive constituting the adhesive layer is not particularly limited. For example, the pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer composed of 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 pressure-sensitive adhesive refers to a pressure-sensitive adhesive containing a (meth) acrylic polymer as a base polymer (a component containing more than 50 mass% of the main component in the polymer component). The same is true for rubber-based adhesives and other adhesives. From the viewpoint of transparency, weather resistance, and the like, a preferable pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer containing an acrylic pressure-sensitive adhesive in a proportion of 50 wt% or more, more preferably 70 wt% or more, and still more preferably 90 wt% or more. The content of the acrylic pressure-sensitive adhesive may be more than 98% by weight, or may be a pressure-sensitive adhesive layer substantially composed of the acrylic pressure-sensitive adhesive.

Here, "(meth) acrylic acid" in the present specification means a meaning including acrylic acid and methacrylic acid. Likewise, "(meth) acryl" is intended to have a meaning including acryl and methacryl, and "(meth) acrylate" is intended to have a meaning including acrylate and methacrylate.

In the present specification, the term (meth) acrylic polymer refers to a polymer containing a (meth) acrylic monomer as a monomer component constituting the (meth) acrylic polymer. That is, it means a polymer containing a monomer unit derived from a (meth) acrylic monomer. The (meth) acrylic monomer herein means a monomer having at least 1 (meth) acryloyl group in 1 molecule.

In one embodiment of the technology disclosed herein, the pressure-sensitive adhesive layer may be suitably prepared using a pressure-sensitive adhesive composition containing a monomer component constituting the (meth) acrylic polymer, although not particularly limited. Hereinafter, such a pressure-sensitive adhesive composition is sometimes referred to as a "(meth) acrylic pressure-sensitive adhesive composition". The term "monomer component constituting a (meth) acrylic polymer" as used herein refers to a monomer component constituting a (meth) acrylic polymer in a pressure-sensitive adhesive obtained from a (meth) acrylic pressure-sensitive adhesive composition. The monomer component may be contained in the (meth) acrylic pressure-sensitive adhesive composition as an unreacted monomer (i.e., in the form of a raw material monomer in which the polymerizable functional group is not reacted), may be contained in the form of a polymer (i.e., as a monomer unit), or may be contained in the form of both of them.

< monomer component >

In one embodiment of the technology disclosed herein, the pressure-sensitive adhesive layer can be formed using a pressure-sensitive adhesive composition containing the following component (a) as a monomer component constituting the (meth) acrylic polymer. In a preferred embodiment, the pressure-sensitive adhesive layer can be suitably formed using a (meth) acrylic pressure-sensitive adhesive composition containing, as monomer components constituting the (meth) acrylic polymer, at least the following component (a), and if necessary, one or both of the following component (B) and the following component (C).

(component (A))

The component (A) is an alkyl (meth) acrylate having an alkyl group with 2 to 18 carbon atoms at the ester end. Hereinafter, an alkyl (meth) acrylate having an alkyl group with a carbon number of X or more and Y or less at the ester end may be referred to as "(meth) acrylic acid C_X-YAlkyl ester ". (meth) acrylic acid C_2-18C in alkyl esters_2-18The structure of the alkyl group is not particularly limited, and any of a straight-chain alkyl group and a branched-chain alkyl group can be used as the alkyl group. As the component (A), the (meth) acrylic acid C may be used alone_2-181 or more of the alkyl esters may be used in combination.

(meth) acrylic acid C having a straight-chain alkyl group at the end of ester_2-18Examples of the alkyl ester include ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, n-nonyl (meth) acrylate, n-decyl (meth) acrylate, n-undecyl (meth) acrylate, n-dodecyl (meth) acrylate, and (meth) propyleneN-tridecyl acid, n-tetradecyl (meth) acrylate, n-pentadecyl (meth) acrylate, n-hexadecyl (meth) acrylate, n-heptadecyl (meth) acrylate, and n-octadecyl (meth) acrylate. (meth) acrylic acid C having a branched alkyl group at the ester end_3-18Examples of the alkyl ester include isopropyl (meth) acrylate, tert-butyl (meth) acrylate, isobutyl (meth) acrylate, isoamyl (meth) acrylate, tert-amyl (meth) acrylate, neopentyl (meth) acrylate, isohexyl (meth) acrylate, isoheptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, isodecyl (meth) acrylate, 2-propylheptyl (meth) acrylate, isoundecyl (meth) acrylate, isododecyl (meth) acrylate, isotridecyl (meth) acrylate, isomyristyl (meth) acrylate, isotentadecyl (meth) acrylate, isocetyl (meth) acrylate, isoheptadecyl (meth) acrylate, tert-butyl (meth) acrylate, isobutyl (meth) acrylate, isoamyl (meth) acrylate, isopropyl (, Isostearyl (meth) acrylate, and the like. The technique disclosed herein may comprise acrylic acid C as the component (A)_4-91 or 2 or more of the alkyl esters are preferably used. As acrylic acid C_4-9Suitable examples of alkyl esters are n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate and isononyl acrylate.

(component (B))

The component (B) is an alicyclic monomer. In the embodiment in which the component (B) is used in combination with the component (a), a pressure-sensitive adhesive layer can be suitably realized which has the preferable storage modulus and other pressure-sensitive adhesive properties (for example, adhesiveness to an adherend) disclosed herein in a well-balanced manner.

The alicyclic monomer is not particularly limited and a monomer having an alicyclic structure-containing group and a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group can be used. As the component (B), 1 kind of such alicyclic monomer may be used alone or 2 or more kinds may be used in combination. Here, the "alicyclic structure-containing group" means a moiety including at least one alicyclic structure. Further, "alicyclic structure" means a saturated or unsaturated carbocyclic structure having no aromaticity. In this specification, a group having an alicyclic structure may be simply referred to as an "alicyclic group". Suitable examples of the alicyclic group include a hydrocarbon group and a hydrocarbyloxy group each having an alicyclic structure.

As an example of a preferable alicyclic monomer in the technology disclosed herein, an alicyclic (meth) acrylate having an alicyclic group and a (meth) acryloyl group can be cited. Specific examples of the alicyclic (meth) acrylate include cyclopropyl (meth) acrylate, cyclobutyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, cyclooctyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and the like, and HPMPA, TMA-2, HCPA and the like represented by the following chemical formulae.

The number of carbons of the alicyclic group (in the case of an alicyclic (meth) acrylate, a portion obtained by removing a (meth) acryloyl group from the alicyclic (meth) acrylate) in the alicyclic monomer is not particularly limited. For example, an alicyclic monomer having an alicyclic group with 4 to 24 (preferably 5 to 18, more preferably 5 to 12) carbon atoms can be used. Among them, cyclohexyl acrylate (CHA), cyclohexyl methacrylate, isobornyl acrylate (IBXA) and isobornyl methacrylate are preferable, CHA and IBXA are more preferable, and CHA is particularly preferable.

(component (C))

The component (C) is a monomer having at least one of a hydroxyl group and a carboxyl group.

As the hydroxyl group-containing monomer, a monomer having a hydroxyl group and having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group can be used without particular limitation. The hydroxyl group-containing monomers may be used alone in 1 kind or in combination of 2 or more kinds. Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, and 12-hydroxylauryl (meth) acrylate; hydroxyalkyl cycloalkyl (meth) acrylates such as (4-hydroxymethylcyclohexyl) methyl (meth) acrylate. In addition, hydroxyethyl (meth) acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, and the like can be cited. Among these, hydroxyalkyl (meth) acrylates are preferable. For example, a hydroxyalkyl (meth) acrylate having a hydroxyalkyl group having 2 to 6 carbon atoms can be preferably used. In a preferred mode, 1 or more than 2 selected from the group consisting of 2-hydroxyethyl acrylate (2HEA), 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate (4HBA) and 4-hydroxybutyl methacrylate may be used as the hydroxyl group-containing monomer. The hydroxyl-containing monomer used in a suitable manner of the technology disclosed herein can be 4HBA alone, 2HEA alone, or a combination of 4HBA and 2 HEA.

As the carboxyl group-containing monomer, a monomer having a carboxyl group and having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group can be used without particular limitation. The carboxyl group-containing monomers may be used alone in 1 kind or in combination of 2 or more kinds. Examples of the carboxyl group-containing monomer include ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, carboxyethyl (meth) acrylate, and (meth) carboxypentyl ester; ethylenically unsaturated dicarboxylic acids such as itaconic acid, maleic acid, fumaric acid, and citraconic acid; metal salts (e.g., alkali metal salts) thereof; anhydrides of the above ethylenically unsaturated dicarboxylic acids such as maleic anhydride and itaconic anhydride, and the like. Among these, acrylic acid and methacrylic acid are preferable, and acrylic acid is particularly preferable.

The technique disclosed herein can be preferably carried out in such a manner that the component (C) contains a hydroxyl group-containing monomer. That is, the component (C) preferably contains only a hydroxyl group-containing monomer, or contains a hydroxyl group-containing monomer and a carboxyl group-containing monomer. (C) When the component (C) contains a hydroxyl group-containing monomer and a carboxyl group-containing monomer, the proportion of the hydroxyl group-containing monomer in the entire component (C) is preferably more than about 50% by weight, and more preferably about 80% by weight or more (for example, about 90% by weight or more). Increasing the proportion of the hydroxyl group-containing monomer in the component (C) is preferable from the viewpoint of reducing metal corrosion or the like due to carboxyl groups. The technique disclosed herein can be preferably carried out in such a manner that the monomer component does not substantially contain a carboxyl group-containing monomer. For example, the proportion of the carboxyl group-containing monomer in the monomer component may be set to less than about 1% by weight, preferably less than about 0.5% by weight, and more preferably less than about 0.2% by weight.

The ratio of the component (A) to the whole monomer component is not particularly limited. From ready to get G'₁₀₀And G'₁₀₀/G'₂₃In the case of a pressure-sensitive adhesive layer in which one or both of the components are suitable values, the proportion of the component (a) is suitably about 90 wt% or less, preferably about 85 wt% or less, and more preferably about 70 wt% or less. In a preferred embodiment, the proportion of the component (a) may be about 60 wt% or less (further about 50 wt% or less, for example, less than about 50 wt%). The proportion of the component (a) is preferably about 30% by weight or more, more preferably about 35% by weight or more, from the viewpoint of initial adhesiveness to an adherend, and the like. In one embodiment, the proportion of the component (A) in the entire monomer component may be, for example, about 30 to 70 wt%.

When the component (B) is contained as the monomer component, the ratio of the component (B) to the whole monomer component is not particularly limited. From ready to get G'₁₀₀And G'₁₀₀/G'₂₃In the case of a pressure-sensitive adhesive layer or the like in which one or both of them are suitable values, the proportion of the component (B) is usually suitably about 3% by weight or more, preferably about 5% by weight or more, and more preferably about 8% by weight or more (for example, about 10% by weight or more). From the viewpoint of initial adhesiveness to an adherend, the proportion of the component (B) is suitably about 65% by weight or less, preferably about 60% by weight or less, and more preferably about 55% by weight or less (further about 50% by weight or less, for example, less than about 50% by weight). In a preferred embodiment, the component (B)The proportion of the monomer component in the whole monomer component may be about 15% by weight or more, about 20% by weight or more, about 25% by weight or more, or about 30% by weight or more (for example, about 35% by weight or more). In one embodiment, the proportion of the component (B) in the entire monomer component may be, for example, about 20 to 50% by weight.

When the component (C) is contained as the monomer component, the ratio of the component (C) to the whole monomer component is not particularly limited. The proportion of the component (C) is typically about 3% by weight or more, preferably about 5% by weight or more, and more preferably about 8% by weight or more (for example, about 10% by weight or more) from the viewpoint of initial adhesiveness to an adherend, and the like. Further, G 'is easily obtained'₁₀₀And G'₁₀₀/G'₂₃In view of the pressure-sensitive adhesive layer in which one or both of the components are suitable values, the proportion of the component (C) is preferably about 35 wt% or less, more preferably about 30 wt% or less, and still more preferably about 25 wt% or less. In one embodiment, the proportion of the component (C) may be, for example, about 15 to 30% by weight.

(optional monomer)

The monomer component in the technology disclosed herein may contain a monomer (hereinafter, also referred to as "arbitrary monomer") other than the above-mentioned component (a), component (B), and component (C).

Examples of such an arbitrary monomer include a heterocyclic ring-containing monomer such as a cyclic nitrogen-containing monomer and a cyclic ether group-containing monomer. Such heterocyclic-containing monomers, as with component (B) above, can help to achieve an adhesive layer that has a good balance of the preferred storage modulus and other adhesive properties or other characteristics disclosed herein. In addition, it may contribute to improvement in adhesion and cohesion of the adhesive. The heterocyclic ring-containing monomers may be used alone in 1 kind or in combination of 2 or more kinds.

As the cyclic nitrogen-containing monomer, a monomer having a nitrogen-containing heterocyclic ring structure and having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group can be used without particular limitation. The nitrogen-containing heterocyclic structure preferably has a nitrogen atom in a cyclic structure. Examples of the cyclic nitrogen-containing monomer include lactam-based vinyl monomers such as N-vinylpyrrolidone, N-vinyl-epsilon-caprolactam and methyl vinylpyrrolidone; oxazoline group-containing monomers such as 2-vinyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, and 2-isopropenyl-2-oxazoline; and cyclic nitrogen-containing vinyl monomers such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole and vinylmorpholine. Other examples of the monomer having a nitrogen-containing heterocyclic ring include (meth) acrylic monomers having a nitrogen-containing heterocyclic ring such as a morpholine ring, a piperidine ring, a pyrrolidine ring, a piperazine ring, or an aziridine ring. Specific examples thereof include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine, and N-acryloylaziridine. Among the above cyclic nitrogen-containing monomers, lactam-based vinyl monomers are preferable, and N-vinylpyrrolidone is more preferable, from the viewpoint of cohesiveness and the like.

As the monomer having a cyclic ether group, a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a cyclic ether group such as an epoxy group or an oxetanyl group can be used without particular limitation. Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, 3, 4-epoxycyclohexylmethyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate glycidyl ether. Examples of the oxetanyl group-containing monomer include 3-oxetanylmethyl (meth) acrylate, 3-methyl-oxetanylmethyl (meth) acrylate, 3-ethyl-oxetanylmethyl (meth) acrylate, 3-butyl-oxetanylmethyl (meth) acrylate, and 3-hexyl-oxetanylmethyl (meth) acrylate.

Other examples of the optional monomer include alkyl (meth) acrylates not belonging to the component (a), that is, alkyl (meth) acrylates having an alkyl group of 1 or 19 or more (for example, 19 to 24) carbon atoms. Specific examples of such alkyl (meth) acrylates include methyl (meth) acrylate, n-nonadecyl (meth) acrylate, iso-nonadecyl (meth) acrylate, n-eicosyl (meth) acrylate, and iso-eicosyl (meth) acrylate. These may be used alone in 1 kind or in combination of 2 or more kinds.

As another example of the arbitrary monomer, a monomer having a functional group other than a hydroxyl group and a carboxyl group can be cited. Such a functional group-containing monomer can be used for introducing a crosslinking point into the (meth) acrylic polymer or for improving the cohesive force of the (meth) acrylic polymer. Examples of the functional group-containing monomer include amide group-containing monomers such as (meth) acrylamide, N-dimethyl (meth) acrylamide, and N-methylol (meth) acrylamide; cyano group-containing monomers such as acrylonitrile and methacrylonitrile; sulfonic acid group-containing monomers such as styrenesulfonic acid, allylsulfonic acid, and 2- (meth) acrylamido-2-methylpropanesulfonic acid; phosphoric acid group-containing monomers such as 2-hydroxyethylacryloyl phosphate; ketone group-containing monomers such as diacetone (meth) acrylamide, diacetone (meth) acrylate, vinyl methyl ketone, and vinyl acetoacetate; isocyanate group-containing monomers such as 2- (meth) acryloyloxyethyl isocyanate; alkoxy group-containing monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; for example, alkoxysilyl group-containing monomers such as 3- (meth) acryloyloxypropyltrimethoxysilane and 3- (meth) acryloyloxypropyltriethoxysilane, and the like. These may be used alone in 1 kind or in combination of 2 or more kinds.

In the monomer components of the technology disclosed herein, in order to adjust Tg of the (meth) acrylic polymer, improve cohesive strength, and the like, any of the above monomers may include copolymerizable monomers other than the above examples, which are copolymerizable with the above components (a), (B), and (C). Examples of such copolymerizable monomers include vinyl carboxylates such as vinyl acetate and vinyl propionate; aromatic vinyl compounds such as styrene, substituted styrene (. alpha. -methylstyrene, etc.), vinyl toluene, etc.; aromatic ring-containing (meth) acrylates such as aryl (meth) acrylates (e.g., phenyl (meth) acrylate), aryloxyalkyl (meth) acrylates (e.g., phenoxyethyl (meth) acrylate), and arylalkyl (meth) acrylates (e.g., benzyl (meth) acrylate); olefin monomers such as ethylene, propylene, isoprene, butadiene, and isobutylene; chlorine-containing monomers such as vinyl chloride and vinylidene chloride; vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether; and macromonomers having a radical polymerizable vinyl group at the terminal of a monomer obtained by polymerizing a vinyl group. These may be used alone in 1 kind or in combination of 2 or more kinds.

The amount of any of these monomers is not particularly limited and may be determined as appropriate. Generally, the total amount of any monomer used is suitably set to less than about 50% by weight, preferably to about 30% by weight or less, more preferably to about 20% by weight or less of the monomer components. The techniques disclosed herein can be preferably practiced in such a way that the total amount of any monomer used is less than about 10 weight percent (e.g., less than about 5 weight percent) of the monomer composition. When any monomer is used, the amount of the monomer is preferably about 0.5% by weight or more, preferably about 0.8% by weight or more, based on the monomer component, from the viewpoint of suitably exerting the effect of improving the adhesive strength and the cohesive strength. The technique disclosed herein can also be preferably carried out in such a manner that substantially no arbitrary monomer is used (for example, in such a manner that the amount of the arbitrary monomer is about 0.3% by weight or less, typically about 0.1% by weight or less of the monomer component).

The above-mentioned component (A), component (B), component (C) and any monomer are typically monofunctional monomers. In addition to such a monofunctional monomer, the monomer component may contain an appropriate amount of a polyfunctional monomer as needed for the purpose of adjusting the storage modulus of the pressure-sensitive adhesive layer. Here, in the present specification, the monofunctional monomer means a monomer having only 1 polymerizable functional group (typically, a radical polymerizable functional group) having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group. In contrast, the polyfunctional monomer means a monomer having at least 2 such polymerizable functional groups as described later.

(polyfunctional monomer)

The polyfunctional monomer is a monomer having a polymerizable functional group (typically, a radical polymerizable functional group) having at least 2 (meth) acryloyl groups, vinyl groups, or the like, and an unsaturated double bond. Examples of the polyfunctional monomer include esters of (meth) acrylic acid with polyhydric alcohols such as ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1, 2-ethylene glycol di (meth) acrylate, 1, 4-butanediol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, 1, 12-dodecanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and tetramethylolmethane tri (meth) acrylate; allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, and the like. Suitable examples of these include trimethylolpropane tri (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, and dipentaerythritol hexa (meth) acrylate. Among them, 1, 6-hexanediol di (meth) acrylate is a preferred example. The polyfunctional monomers may be used alone in 1 kind or in combination of 2 or more kinds. From the viewpoint of reactivity and the like, a polyfunctional monomer having 2 or more acryloyl groups is generally preferable.

The amount of the polyfunctional monomer to be used is not particularly limited, and may be suitably set in such a manner as to achieve the intended use of the polyfunctional monomer. In one embodiment, the amount of the polyfunctional monomer used may be about 3% by weight or less, preferably about 2% by weight or less, and more preferably about 1% by weight or less (e.g., about 0.5% by weight or less) of the monomer component, from the viewpoint of achieving a good balance between the preferred storage modulus and other adhesive properties and other characteristics disclosed herein. The lower limit of the amount of the polyfunctional monomer used is not particularly limited as long as it is more than 0% by weight. The effect of the polyfunctional monomer in use can be suitably exhibited by setting the amount of the polyfunctional monomer to about 0.001% by weight or more (for example, about 0.01% by weight or more) of the monomer component.

The total amount of the component (a), the component (B) and the component (C) is typically more than about 50% by weight, preferably about 70% by weight or more, more preferably about 80% by weight or more, and still more preferably about 90% by weight or more of the whole monomer components, although not particularly limited. The technique disclosed herein can be preferably carried out in such a manner that the ratio of the above-mentioned total amount is about 95% by weight or more (e.g., about 99% by weight or more). The proportion of the above total amount may also be 100% by weight. The technique disclosed herein can be preferably carried out so that the total amount of the above monomers accounts for 99.999 wt% or less (for example, 99.99 wt% or less) of the total amount of the above monomers.

The Tg of the copolymer corresponding to the composition of the monomer component is preferably about-20 ℃ or less, more preferably about-25 ℃ or less, from the viewpoint of adhesiveness, low temperature characteristics, and the like of the adhesive sheet, although not particularly limited. Further, G 'is easily obtained'₁₀₀And G'₁₀₀/G'₂₃The Tg of the copolymer is suitably about-55 ℃ or higher, preferably about-50 ℃ or higher, and more preferably about-45 ℃ or higher, for an adhesive layer or the like in which one or both of them are suitable values. The techniques disclosed herein can also be preferably practiced in such a way that the Tg of the above-described copolymers is above about-40 deg.C (e.g., above about-35 deg.C).

Here, the Tg of the copolymer corresponding to the composition of the monomer component means the Tg obtained by the Fox equation based on the composition of the monomer component. The 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.

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 (weight-based copolymerization ratio) of the monomer i in the copolymer, and Tgi represents the glass transition temperature (unit: K) of the homopolymer of the monomer i. However, in the present specification, the calculation of Tg is performed in consideration of only the monofunctional monomer. Therefore, when the monomer component contains a polyfunctional monomer, the total amount of the monofunctional monomers contained in the monomer component is defined as 100% by weight, and the Tg is calculated based on the Tg of the homopolymer of each monofunctional monomer and the weight fraction of the monofunctional monomer with respect to the total amount.

The glass transition temperature of the homopolymer used for calculating Tg was the value described in the publicly known data. For example, the following monomers are used as the glass transition temperature of the homopolymer of the monomer.

Regarding the glass transition temperature of the homopolymer of the monomer other than those exemplified above, the value described in Polymer Handbook ("Polymer Handbook") (3 rd edition, John Wiley & Sons, Inc, 1989) was used. The highest value is used for monomers having various numerical values described in this document.

As for the monomer having no description of the glass transition temperature of the homopolymer in the above-mentioned handbook of polymers, the following measurement method was used (see Japanese patent application laid-open No. 2007-51271). Specifically, 100 parts by weight of a monomer, 0.2 parts by weight of azobisisobutyronitrile and 200 parts by weight of ethyl acetate as a polymerization solvent were put into a reactor equipped with a thermometer, a stirrer, a nitrogen introduction tube and a reflux condenser, and stirred for 1 hour while flowing nitrogen. After removing oxygen from the polymerization system in this manner, the temperature was raised to 63 ℃ and the reaction was carried out for 10 hours. Then, the mixture was cooled to room temperature to obtain a homopolymer solution having a solid content of 33% by weight. This homopolymer solution was cast and coated on a release film, and dried to prepare a test sample (sheet-like homopolymer) having a thickness of about 2 mm. The test sample was punched out into a disk shape having a diameter of 7.9mm, and sandwiched between parallel plates, and viscoelasticity was measured in a shear mode at a temperature rise rate of 5 ℃/min in a temperature range of-70 to 150 ℃ while applying shear strain having a frequency of 1Hz using a viscoelasticity test apparatus (TA Instruments co., ltd., inc., ARES), and the peak top temperature of tan δ (loss tangent) was taken as the glass transition temperature.

< adhesive composition >

The adhesive layer disclosed herein can be formed using an adhesive composition containing a monomer component of the above-described composition in the form of a polymer, an unpolymerized (i.e., a form 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 form a pressure-sensitive adhesive by curing with an active energy ray such as an ultraviolet ray or a radiation ray (active energy ray-curable pressure-sensitive adhesive composition); hot melt adhesive compositions which form an adhesive when coated in a molten state under heating and cooled to around room temperature, and the like.

Here, the "active energy ray" in the present specification means an energy ray having energy capable of causing a chemical reaction such as a polymerization reaction, a crosslinking reaction, and decomposition of an initiator. Examples of the active energy rays mentioned herein include light such as ultraviolet rays, visible rays, infrared rays and the like; radiation rays such as α rays, β rays, γ rays, electron rays, neutron rays, and X rays.

The adhesive composition typically contains at least a part of the monomer components of the composition in the form of a polymer (may be a part of the monomer species or a part of the weight). 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 (typically, in the presence of a thermal polymerization initiator), such as solution polymerization, emulsion polymerization, or bulk polymerization; photopolymerization by irradiation with light such as ultraviolet light (typically, in the presence of a photopolymerization initiator); radiation polymerization by irradiation with radiation such as β -rays and γ -rays. Among them, photopolymerization is preferable. 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 customary photopolymerization initiator or thermal polymerization 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 combination of 2 or more kinds.

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.

Specific examples of the ketal-based photopolymerization initiator include 2, 2-dimethoxy-1, 2-diphenylethan-1-one (for example, product name "Irgacure 651" manufactured by BASF corporation), and the like.

Specific examples of the acetophenone-based photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone (for example, trade name "Irgacure 184" manufactured by BASF), 4-phenoxydichloroacetophenone, 4-tert-butyldichloroacetophenone, 1- [4- (2-hydroxyethoxy) -phenyl ] -2-hydroxy-2-methyl-1-propan-1-one (for example, trade name "Irgacure 2959" manufactured by BASF), 2-hydroxy-2-methyl-1-phenyl-propan-1-one (for example, trade name "Darocure 1173" manufactured by BASF), methoxyacetophenone, and the like.

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

Specific examples of the acylphosphine oxide-based photopolymerization initiator include bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide (for example, trade name "Irgacure 819" manufactured by BASF), bis (2,4, 6-trimethylbenzoyl) -2, 4-di-n-butoxyphenylphosphine oxide, 2,4, 6-trimethylbenzoyldiphenylphosphine oxide (for example, trade name "Lucirin TPO" manufactured by BASF), 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, polyvinylbenzophenone, α -hydroxycyclohexylphenylketone, and the like.

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

The thermal polymerization initiator is not particularly limited, and for example, an azo polymerization initiator, a peroxide initiator, a redox initiator comprising a combination of a peroxide and a reducing agent, a substituted ethylene initiator, and the like can be used. More specifically, azo initiators such as 2,2 ' -azobisisobutyronitrile, 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 is preferably carried out at a temperature of, for example, about 20 to 100 ℃ (typically about 40 to 80 ℃).

The amount of the thermal polymerization initiator or the photopolymerization initiator is not particularly limited, and may be a usual amount in accordance with the polymerization method, polymerization system, or the like. 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.

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

One preferred embodiment of the adhesive composition comprises the polymerization reaction of a monomer mixture comprising at least a portion of the monomeric content (starting monomers) of the composition. Typically, a part of the monomer component is contained in the form of a polymer, and the remaining monomer is contained in the form of an unreacted monomer. The polymerization reactants of the above monomer mixture may be prepared by polymerizing at least a portion of the monomer mixture.

The polymerization reactant 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 typically, is in a slurry state (viscous liquid state). Hereinafter, the partial polymer having the above-described properties may be referred to as a "monomer slurry" or simply as a "slurry".

The polymerization method for obtaining the above-mentioned 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 polymerization conditions such as the amount of light irradiation (light amount).

The polymerization conversion rate (monomer conversion) of the monomer mixture in the partial polymer is not particularly limited. The polymerization conversion rate may be, for example, about 70% by weight or less, and preferably about 60% by weight or less. From the viewpoint of ease of preparation, coatability, and the like of the adhesive composition containing the above partial polymer, the polymerization conversion rate is generally suitably about 50% by weight or less, 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 is usually 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 of the raw material monomers by an appropriate polymerization method (e.g., photopolymerization method). The pressure-sensitive adhesive composition containing the above partial polymer may be blended with other components (for example, a photopolymerization initiator, a polyfunctional monomer, a crosslinking agent, an acrylic oligomer described later, and the like) used as needed. The method of compounding such other components is not particularly limited, and for example, they may be contained in the monomer mixture in advance or may be added to the partial polymer.

The adhesive composition disclosed herein may be in a form in which a complete polymer of a monomer mixture containing a part of the types of monomers in the monomer components (raw material monomers) is dissolved in the remaining types of 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, "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 of the monomer component and the non-polymer in this way, a photopolymerization method can be preferably used. As for the adhesive composition containing the polymerization reactant 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 pressure-sensitive adhesive composition containing the polymerization reaction product is further cured to form a pressure-sensitive adhesive, photocuring can be performed without adding a new photopolymerization initiator. Alternatively, the pressure-sensitive adhesive composition may have a composition in which a photopolymerization initiator is added to a polymerization reaction product prepared by a photopolymerization method as needed. The additional photopolymerization initiator may be the same as or different from the photopolymerization initiator used to prepare 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 a preferred embodiment, photopolymerization in forming the adhesive from the adhesive composition can 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)

Another preferred embodiment of the adhesive composition comprises the monomer components of the adhesive composition in the form of a complete polymer. Such an adhesive composition may be in the form of, for example, a solvent-based adhesive composition containing a (meth) acrylic polymer as a complete polymer of a monomer component in an organic solvent, or an aqueous dispersion-type adhesive composition in which the (meth) acrylic polymer is dispersed in an aqueous solvent.

(crosslinking agent)

The adhesive compositions disclosed herein may contain a crosslinking agent. As the crosslinking agent, a crosslinking agent known or customary in the art of adhesives can be used. Examples of the crosslinking agent include epoxy crosslinking agents, isocyanate crosslinking agents, silicone crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, silane crosslinking agents, alkyl ether melamine crosslinking agents, and metal chelate crosslinking agents. These may be used alone in 1 kind or in combination of 2 or more kinds.

The content of the crosslinking agent (the total amount of 2 or more crosslinking agents when included) is not particularly limited. From the viewpoint of realizing an adhesive agent that exhibits adhesive properties such as adhesive strength and cohesive strength in a well-balanced manner, the content of the crosslinking agent is usually suitably about 5 parts by weight or less, preferably about 0.001 to 5 parts by weight, more preferably about 0.001 to 4 parts by weight, and still more preferably about 0.001 to 3 parts by weight, relative to 100 parts by weight of the monomer component contained in the adhesive agent composition. Alternatively, the pressure-sensitive adhesive composition may be one which does not contain such a crosslinking agent.

((meth) acrylic oligomer)

The pressure-sensitive adhesive composition disclosed herein may contain a (meth) acrylic oligomer from the viewpoint of improving the adhesive strength and the like. As the (meth) acrylic oligomer, it is preferable to use a polymer having a Tg higher than that of a copolymer corresponding to the composition of the above monomer component (typically, approximately corresponding to the Tg of a (meth) acrylic polymer contained in an adhesive formed of the adhesive composition). The adhesive strength of the adhesive can be improved by containing the (meth) acrylic oligomer.

The (meth) acrylic oligomer preferably has a Tg of about 0 ℃ or higher and about 300 ℃ or lower, preferably about 20 ℃ or higher and about 300 ℃ or lower, and more preferably about 40 ℃ or higher and about 300 ℃ or lower. When Tg is in the above range, the adhesive strength can be suitably improved. The Tg of the (meth) acrylic oligomer is calculated based on the Fox equation, similarly to the Tg of the copolymer corresponding to the composition of the monomer component.

The weight average molecular weight (Mw) of the (meth) acrylic oligomer is typically about 1000 or more and less than about 30000, preferably about 1500 or more and less than about 20000, and more preferably about 2000 or more and less than about 10000. When Mw is within the above range, favorable adhesion and holding characteristics can be obtained, which is preferable. The Mw of the (meth) acrylic oligomer can be measured by Gel Permeation Chromatography (GPC) and determined as a value in terms of standard polystyrene. Specifically, HPLC8020 manufactured by Tosoh corporation used 2 TSK gelGMH-H (20) columns, and the measurement was carried out with tetrahydrofuran solvent at a flow rate of about 0.5 ml/min.

Examples of the monomer constituting the (meth) acrylic oligomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, alkyl (meth) acrylates such as 2-ethylhexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, and dodecyl (meth) acrylate; esters of (meth) acrylic acid and alicyclic alcohols such as cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate; aryl (meth) acrylates such as phenyl (meth) acrylate and benzyl (meth) acrylate; (meth) acrylic acid esters derived from alcohols derived from terpene compounds, and the like. Such (meth) acrylates may be used in 1 kind alone or in combination of 2 or more kinds.

From the viewpoint of further improving the adhesiveness of the pressure-sensitive adhesive layer, the (meth) acrylic oligomer preferably contains, as a monomer unit, an alkyl (meth) acrylate having a branched structure with an alkyl group such as isobutyl (meth) acrylate or tert-butyl (meth) acrylate; esters of (meth) acrylic acid and alicyclic alcohols such as cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate; acrylic monomers having a bulky structure typified by (meth) acrylates having a cyclic structure such as phenyl (meth) acrylate and aryl (meth) acrylates such as benzyl (meth) acrylate. In addition, when ultraviolet light is used for synthesizing the (meth) acrylic oligomer or for producing the pressure-sensitive adhesive layer, it is preferable that the monomer has a saturated bond and an alkyl (meth) acrylate in which an alkyl group has a branched structure or an ester of (meth) acrylic acid and an alicyclic alcohol can be suitably used as a monomer constituting the (meth) acrylic oligomer, from the viewpoint of preventing polymerization from being easily inhibited.

From such a viewpoint, examples of suitable (meth) 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), and copolymers of CHMA and isobutyl methacrylate (IBMA), copolymers of CHMA and IBXMA, copolymers of CHMA and Acryloylmorpholine (ACMO), copolymers of CHMA and Diethylacrylamide (DEAA), copolymers of ADA and Methyl Methacrylate (MMA), copolymers of DCPMA and IBXMA, and copolymers of DCPMA and MMA.

When the (meth) acrylic oligomer is contained in the adhesive composition disclosed herein, the content thereof is not particularly limited. From the viewpoint of easily realizing the pressure-sensitive adhesive layer having a preferred storage modulus disclosed herein, the content of the (meth) acrylic oligomer is generally preferably about 20 parts by weight or less, more preferably about 15 parts by weight or less, and still more preferably about 10 parts by weight or less, relative to 100 parts by weight of the monomer component contained in the pressure-sensitive adhesive composition. The technology disclosed herein can be preferably carried out even without using a (meth) acrylic oligomer.

In addition, the adhesive composition disclosed herein may contain various additives known in the field of adhesives as needed. For example, colorants such as dyes and pigments, antistatic agents, surfactants, plasticizers, tackifier resins, surface lubricants, leveling agents, softeners, antioxidants, light stabilizers, ultraviolet absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particulates, foils, and the like may be added as appropriate depending on the application.

In the technique disclosed herein, an active energy ray-curable adhesive composition (typically, a photocurable adhesive composition) can be preferably used as the adhesive composition used for forming the adhesive layer. The active energy ray-curable adhesive composition is preferably a composition substantially free of an organic solvent from the viewpoint of environmental hygiene and the like. For example, adhesive compositions having an organic solvent content of about 5 wt% or less (more preferably about 3 wt% or less, e.g., about 0.5 wt% or less) are preferred. Further, as described below, since the pressure-sensitive adhesive layer is suitable for forming a form in which a liquid film of the pressure-sensitive adhesive composition is cured between the release surfaces of the pair of release films, a pressure-sensitive adhesive composition substantially free of a solvent (meaning containing an organic solvent and an aqueous solvent) is preferred. For example, an adhesive composition having a solvent content of about 5 wt% or less (more preferably about 3 wt% or less, for example about 0.5 wt% or less) is preferred. Here, the solvent refers to a volatile component to be removed in the process of forming the pressure-sensitive adhesive layer, that is, a volatile component which is not intended to be a constituent component of the finally formed pressure-sensitive adhesive layer.

< method for producing adhesive sheet >

The method for producing the adhesive sheet disclosed herein is not particularly limited. For example, a substrate-less double-sided adhesive sheet including an adhesive layer can be obtained by applying any of the adhesive compositions disclosed herein to a release surface of a release film and drying or curing the adhesive layer to form the adhesive layer. The pressure-sensitive adhesive layer formed on the release film in this manner is bonded (transferred) to the non-release surface of the support substrate, whereby a single-sided pressure-sensitive adhesive sheet with a substrate can be obtained. As another method for producing a single-sided pressure-sensitive adhesive sheet with a substrate, there is a method in which a pressure-sensitive adhesive composition is directly applied to a non-release surface of a support substrate and dried or cured. The double-sided pressure-sensitive adhesive sheet with a substrate can be produced by a method of transferring a pressure-sensitive adhesive layer formed on a release film onto a support substrate, a method of directly applying a pressure-sensitive adhesive composition onto a support substrate and drying or curing the pressure-sensitive adhesive composition, a method of combining these, or the like.

As a method for applying the adhesive composition, various conventionally known methods can be used. Specific examples thereof include roll coating methods, roll-and-lick coating methods, gravure coating methods, reverse coating methods, roll brushing methods, spray coating methods, dip roll coating methods, bar coating methods, blade coating methods, air knife coating methods, curtain coating methods, lip coating methods, extrusion coating methods using a die coater, and the like.

The pressure-sensitive adhesive sheet disclosed herein can be suitably produced by a method comprising drying or curing a liquid film of a pressure-sensitive adhesive composition on a release surface of a release film to form a pressure-sensitive adhesive layer having a first pressure-sensitive adhesive surface as a cured surface on the release surface. By this method, the adhesive composition (liquid film) in a fluid state can be dried or cured by being brought into contact with the release surface, and the smoothness of the surface of the adhesive layer formed by being brought into contact with the release surface can be controlled with high accuracy. For example, by using a release film having a release surface with appropriate smoothness, the first pressure-sensitive adhesive surface with desired smoothness can be stably (with good reproducibility).

The pressure-sensitive adhesive sheet disclosed herein can be preferably produced by a method including forming a pressure-sensitive adhesive layer by curing a liquid film of the pressure-sensitive adhesive composition between release surfaces of a pair of release films. This method is suitable as a method for producing a substrate-less double-sided adhesive sheet in which the ten-point average roughness of the first adhesive surface and the ten-point average roughness of the second adhesive surface are both within the preferred ranges disclosed herein. The double-sided pressure-sensitive adhesive sheet without a substrate obtained in this way is also preferably used for the production of a single-sided pressure-sensitive adhesive sheet with a substrate and a double-sided pressure-sensitive adhesive sheet with a substrate by sticking the double-sided pressure-sensitive adhesive sheet without a substrate to the non-release surface of a support substrate. As a method of disposing a liquid film of the adhesive composition between the release surfaces of the pair of release films, a method of applying a liquid adhesive composition to the release surface of the first release film and then covering the liquid film of the adhesive composition with the second release film may be employed. As another method, a method may be mentioned in which the first release film and the second release film are supplied between a pair of rollers with their release surfaces facing 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 can suppress the roughening of the pressure-sensitive adhesive layer due to the difference in thermal expansion coefficient between the release film and the pressure-sensitive adhesive layer, and can form a pressure-sensitive adhesive surface having higher smoothness.

The gel fraction of the pressure-sensitive adhesive layer disclosed herein is not particularly limited, and is usually preferably 99.5 wt% or less, more preferably 20 to 99.5 wt%, and still more preferably 50 to 99.5 wt%. When the pressure-sensitive adhesive composition contains a crosslinking agent, the gel fraction can be controlled by adjusting the amount of the crosslinking agent to be added and considering the influence of the crosslinking temperature and the crosslinking time.

Although not particularly limited, the haze value of the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet disclosed herein, which has a thickness of 50 μm, is preferably 2% or less. The above haze value of the adhesive layer for optical use is particularly significant to be 2% or less. The haze value of the adhesive layer is preferably 0 to 1.5%, more preferably 0 to 1%. The haze value can be measured by attaching a pressure-sensitive adhesive layer formed so as to have a thickness of about 50 μm to one surface of an alkali glass plate and using a haze meter. As the haze meter, MR-100 manufactured by village color technology research or its equivalent can be used. In the measurement, the alkali glass plate to which the pressure-sensitive adhesive layer was attached was disposed so that the pressure-sensitive adhesive layer became the light source side. When the alkali glass itself has a haze value, the haze value of the alkali glass plate itself is subtracted from the measured value to obtain a value, which is used as the haze value of the adhesive layer.

< peeling film >

The release film in the technique disclosed herein is not particularly limited, and may be appropriately selected according to the purpose. Non-limiting examples of release films that can be used include: a release film having a release treatment layer on one or both surfaces of a release film substrate, the release treatment layer having a release surface on the surface thereof; 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 substrate, a plastic film, paper (resin-impregnated paper, resin-laminated paper, or the like) or the like can be used. The release treatment layer may be formed by surface-treating the release film base with a release treatment agent. Examples of the release treatment agent include a silicone release treatment agent, a long-chain alkyl release treatment agent, a fluorine release treatment agent, molybdenum (IV) sulfide, and the like. In one embodiment, a release film having a release treatment layer obtained by using a silicone release treatment agent can be preferably used.

As the release film disclosed herein, a release film having a release treatment layer on the surface of a plastic film as a release film base material can be preferably used. The material constituting such a plastic film may be arbitrarily selected from the same materials as exemplified as the plastic film for the supporting base material. From the viewpoint of dimensional stability and strength, a plastic film comprising a polyester resin film (typically, a polyethylene terephthalate film) can be preferably used. Preferably a plastic film having transparency at least in a part of the area.

In the technique disclosed herein, the plastic film used as the support substrate or the release film substrate may be any of a non-stretched film, a uniaxially stretched film, and a biaxially stretched film. The plastic film may have a single-layer structure or a multilayer structure including 2 or more sub-layers. The plastic film may contain known additives that can be used in a support substrate of a pressure-sensitive adhesive sheet or a release film substrate, such as an antioxidant, 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 plastic film, the additives may be mixed in all of the sub-layers or only a part of the sub-layers.

As the release film in the technology disclosed herein, a release film having a release treatment layer on the surface of a plastic film (release film substrate) and having no particles or particles having a diameter of 5 μm or less can be preferably used. Particles (particularly inorganic particles) having a diameter of more than 5 μm contained in the release film can reduce the smoothness of the release surface in a free state of the release film. Further, even if the release film containing particles having a diameter of more than 5 μm has high smoothness in a free state, the particles may protrude from the release film due to bending deformation, stretching deformation, compression in the thickness direction, or the like of the release film, thereby reducing the smoothness of the release surface and further reducing the smoothness of the pressure-sensitive adhesive surface in contact with the release surface. In one embodiment, a release film substantially free of particles having a diameter of more than 5 μm, that is, a release film free of particles having a diameter of more than 5 μm except for impurities and the like which are not intentionally mixed may be used.

The particles having a diameter of more than 5 μm may be inorganic particles that can be blended in the release film base material for the purpose of, for example, a lubricant, a pigment, a filler, or the like. Non-limiting examples of the inorganic particles may include silica, alumina, kaolin, talc, mica, calcium carbonate, and the like.

The thickness of the release film is not particularly limited. In view of achieving both strength and flexibility, it is generally preferable to use a release film having a thickness of about 10 μm to about 500 μm. The thickness of the release film is preferably about 20 μm or more, and more preferably about 25 μm or more (e.g., about 30 μm or more), from the viewpoint of suppressing a decrease in smoothness of the pressure-sensitive adhesive surface due to an external force applied through the release film (e.g., a decrease in smoothness due to impurities that may be mixed in when the pressure-sensitive adhesive sheet with the release film is spirally wound onto the pressure-sensitive adhesive surface via the release film). From the viewpoint of handling properties (e.g., ease of winding) of the release film itself or the pressure-sensitive adhesive sheet with a release film, the thickness of the release film is usually preferably about 250 μm or less, more preferably about 125 μm or less (e.g., about 100 μm or less), and still more preferably about 80 μm or less. In one embodiment, a release film having a thickness of about 75 μm or less (e.g., about 50 μm or less) can be preferably used.

With respect to the release film-equipped adhesive sheet disclosed herein, the ten-point average roughness (Rz) of the release surface of the first release film in contact with the first adhesive surface of the adhesive sheet_R1) For example, about 2000nm or less can be set. Rz is from the viewpoint of suppressing reduction in smoothness of the first pressure-sensitive adhesive surface during storage of the pressure-sensitive adhesive sheet with a release film_R1Suitably about 1500nm or less, preferably about 1000nm or less, more preferably about 500nm or less, and still more preferably about 300nm or less (e.g., about 250nm or less). When the first pressure-sensitive adhesive surface is a surface of a pressure-sensitive adhesive layer formed of a liquid pressure-sensitive adhesive composition on a release surface of a first release film, Rz is preferably used as the first release film_R1A release film having a thickness of about 1200nm or less (typically about 700nm or less, more preferably about 500nm or less, still more preferably about 400nm or less, for example, about 300nm or less). Rz_R1The lower limit of (b) is not particularly limited. Ease of manufacture and handling of the release film from the firstFrom the viewpoint of workability, etc., Rz can be preferably used in one embodiment_R1A first release film of about 50nm or more (e.g., about 100nm or more).

When the release film-equipped pressure-sensitive adhesive sheet disclosed herein is in the form of a release film-equipped double-sided pressure-sensitive adhesive sheet comprising a double-sided pressure-sensitive adhesive sheet, a first release film and a second release film, the ten-point average roughness (Rz) of the release surface of the second release film in contact with the second pressure-sensitive adhesive surface of the double-sided pressure-sensitive adhesive sheet is_R2) The thickness is not particularly limited, and may be, for example, about 3000nm or more. In one embodiment, Rz can be preferably used_R2A second release film of less than about 3000nm, preferably less than about 2000 nm. Ten-point average roughness Rz of the second adhesive surface_A2In the mode of 1000nm or less, Rz is considered to be the one which suppresses the reduction in smoothness of the second pressure-sensitive adhesive surface_R2Suitably about 2000nm or less (typically about 1500nm or less, preferably about 1000nm or less, more preferably about 500nm or less, even more preferably about 300nm or less, for example about 250nm or less). When the second pressure-sensitive adhesive surface is a surface of a pressure-sensitive adhesive layer formed of a liquid pressure-sensitive adhesive composition on a release surface of a second release film, Rz is preferably used as the second release film_R2A release film having a thickness of about 1200nm or less (typically about 700nm or less, more preferably about 500nm or less, still more preferably about 400nm or less, for example, about 300nm or less). Rz_R2The lower limit of (b) is not particularly limited. In one embodiment, Rz can be preferably used_R2A second release film of about 50nm or more (e.g., about 100nm or more).

In the technique disclosed herein, the release surface of the release film constituting the release film-equipped pressure-sensitive adhesive sheet preferably has smoothness similar to the smoothness of the pressure-sensitive adhesive surface with which the release film is in contact. This makes it possible to more effectively suppress the change in smoothness of the pressure-sensitive adhesive surface during storage of the pressure-sensitive adhesive sheet with a release film, and to improve the performance stability of the pressure-sensitive adhesive sheet. In one embodiment of the release film-attached pressure-sensitive adhesive sheet, the difference in the ten-point average roughness between the first pressure-sensitive adhesive surface and the first release surface in contact with the first pressure-sensitive adhesive surface is, | Rz_R1-Rz_A1The |(s) may be set to about 300nm or less (e.g., about 250nm or less), and are preferably set toAbout 150nm or less, more preferably about 100nm or less. In addition, from the viewpoint of the performance stability of the psa sheet, the ten-point average roughness of the first psa surface is preferably smaller than the ten-point average roughness of the first release surface. That is, Rz is preferable_A1＜Rz_R1Satisfying the above | Rz_R1-Rz_A1The value of |, and Rz_A1＜Rz_R1The release film-attached pressure-sensitive adhesive sheet of at least one (preferably both) of (a) and (b) can be suitably produced by a method including drying or curing a liquid film of a pressure-sensitive adhesive composition on a release surface of a first release film constituting the release film-attached pressure-sensitive adhesive sheet, for example.

In the case where the release film-equipped pressure-sensitive adhesive sheet disclosed herein is in the form of a release film-equipped double-sided pressure-sensitive adhesive sheet including a double-sided pressure-sensitive adhesive sheet, a first release film and a second release film, in one embodiment, | Rz, which is the difference in ten-point average roughness between the second pressure-sensitive adhesive surface and the second release surface in contact with the second pressure-sensitive adhesive surface_R2The value of-RzA 2| may be set to about 300nm or less (e.g., about 250nm or less), preferably about 150nm or less, and more preferably about 100nm or less. In addition, from the viewpoint of the performance stability of the psa sheet, the ten-point average roughness of the second psa surface is preferably smaller than the ten-point average roughness of the second release surface. That is, Rz is preferable_A2＜Rz_R2. Satisfies the above-mentioned | Rz_R2-Rz_A2The value of |, and Rz_A2＜Rz_R2The release film-attached pressure-sensitive adhesive sheet of at least one (preferably both) of (a) and (b) can be suitably produced by a method including, for example, curing a liquid film of a pressure-sensitive adhesive composition between a release surface of a first release film and a release surface of a second release film as described later.

The smoothness of the back surface (i.e., the surface opposite to the release surface) of the release film constituting the release film-equipped adhesive sheet is not particularly limited. In the pressure-sensitive adhesive sheet with a release film that can be wound in a spiral shape, the ten-point average roughness of the back surface of the release film is preferably set to about 5000nm or less (preferably about 4000nm or less, for example, about 3000nm or less) from the viewpoint of preventing a reduction in smoothness of the pressure-sensitive adhesive surface due to the irregularities on the back surface in the wound form.

Bonding as disclosed hereinThe sheet (may be a pressure-sensitive adhesive sheet included in a pressure-sensitive adhesive sheet with a release film, the same applies hereinafter) may be preferably used in such a manner that the release film on the first pressure-sensitive adhesive surface is replaced with another release film until the pressure-sensitive adhesive sheet is attached to an adherend. Hereinafter, the replaced release film is also referred to as a "replacement film". The ten-point average roughness (Rz) of the first release surface (i.e., the release surface disposed in contact with the first adhesive surface) of the replacement film_E1) The wavelength is not particularly limited, and may be, for example, about 50nm or more (typically about 100nm or more). In one embodiment, Rz can be preferably used_E1Replacement films exceeding about 250nm (more preferably exceeding about 500nm, e.g., exceeding about 700 nm). Use of the adhesive sheet disclosed herein in Rz_E1The effect of suppressing the reduction in smoothness of the first pressure-sensitive adhesive surface can be effectively exhibited even in the use mode of the replacement film of about 1000nm or more (further about 1200nm or more, for example, about 1500nm or more). Rz_E1The upper limit of (b) is not particularly limited. It is generally preferred to use Rz_E1A replacement film of about 3000nm or less (typically about 2000nm or less). Changing Rz of thin films in one mode_E1May be about 1500nm or less, or about 1000nm or less. As the replacement film, a film having the same composition (material, thickness, surface roughness, etc.) as the peeled film before replacement may be used, or a film having a different composition may be used.

In a preferred embodiment, Rz can be used as the replacement film_E1The value is larger than the ten-point average roughness (Rz) of the first release surface of the release film before replacement (which may be the release film produced initially)_R1) Large thin films. In one approach Rz may be used_E1/Rz_R1About 2 or more (preferably about 3 or more) replacement film. The adhesive sheet disclosed herein is used, for example, in Rz_E1/Rz_R1Even in the use form of the replacement film of about 5 or more (further about 7 or more), the effect of suppressing the reduction in smoothness of the first pressure-sensitive adhesive surface can be effectively exhibited. Rz_E1/Rz_R1The upper limit of (b) is not particularly limited, but is usually suitably about 20 or less (typically about 15 or less, for example about 10 or less).

< use >)

The pressure-sensitive adhesive layer or the pressure-sensitive adhesive sheet disclosed herein has high smoothness of the pressure-sensitive adhesive surface, and the smoothness of the pressure-sensitive adhesive surface is not easily impaired, and therefore is suitable for optical applications. For example, an adhesive optical member using an optical member as the supporting base material is useful. Such an adhesive optical member may be understood as a single-sided adhesive sheet with a substrate in the form of an optical member as a supporting substrate on the first adhesive side or the second adhesive side of any of the double-sided adhesive sheets disclosed herein. Preferably, the second adhesive surface has an optical member. In this aspect, a release film-equipped pressure-sensitive adhesive optical member having a release film on the first pressure-sensitive adhesive surface can be configured.

When an optical film is used as the optical member, the pressure-sensitive adhesive optical member can be used as an optical film with a pressure-sensitive adhesive layer. As the optical film, a polarizing plate, a retardation plate, an optical compensation film, a brightness enhancement film, a Hard Coat (HC) film, an antireflection film, an impact absorption film, an anti-fouling film, a photochromic film, a light control film, a wavelength selective absorption film, a wavelength conversion film, a film obtained by laminating these films, and the like can be used. The adhesive layer or sheet disclosed herein is also suitable for use in the ophthalmic field. The pressure-sensitive adhesive layer or the pressure-sensitive adhesive sheet of the present invention is not limited to the optical use and the ophthalmic use described above, and can be applied to various uses in the form of a pressure-sensitive adhesive sheet having a support such as a stain-resistant film, a heat-insulating film, or a buffer absorbing film, which is generally used.

Matters disclosed according to the present specification include the following.

(1) An adhesive sheet comprising an adhesive layer,

the adhesive sheet has a first side and a second side,

the first surface is a first adhesive surface formed of one surface of the adhesive layer,

a ten-point average roughness (Rz) of the first adhesive surface_A1) Is a molecular weight of about 1000nm or less,

storage modulus at 100 ℃ (G ') of the adhesive layer'₁₀₀) Is about 0.08MPa or more.

(2) The adhesive sheet according to the item (1), wherein the adhesive layer has a storage modulus at 100 ℃ (G'₁₀₀) And storage modulus at 23 ℃ (G'₂₃) The ratio of the ratio is about 35% or more.

(3) The adhesive sheet according to the item (1) or (2), wherein the adhesive layer has a storage modulus at 23 ℃ (G'₂₃) Less than about 0.30 MPa.

(4) The adhesive sheet according to any one of the above (1) to (3), wherein the double-sided adhesive sheet is configured such that the second surface is a second adhesive surface.

(5) The adhesive sheet according to the item (4), wherein the second adhesive surface has a ten-point average roughness (Rz)_A2) Is about 2000nm or less (e.g., about 1000nm or less).

(6) The adhesive sheet according to the above (4) or (5), wherein the second adhesive surface is formed by the other surface of the adhesive layer.

(7) The adhesive sheet according to any one of the items (4) to (6), wherein the first adhesive surface has a ten-point average roughness (Rz)_A1) And a ten-point average roughness (Rz) of the second adhesive surface_A2) Is about 500nm or less.

(8) The adhesive sheet according to any one of the items (4) to (7), wherein the first adhesive surface has a ten-point average roughness (Rz)_A1) And a ten-point average roughness (Rz) of the second adhesive surface_A2) All below about 500 nm.

(9) The adhesive sheet according to any one of the items (4) to (8), wherein the first adhesive surface has a ten-point average roughness (Rz)_A1) A ten-point average roughness (Rz) of the second adhesive surface_A2) Difference (| Rz)_A1-Rz_A2I) is about 250nm or less.

(10) The adhesive sheet according to any one of the above (1) to (9), wherein the adhesive sheet is a substrate-less double-sided adhesive sheet comprising a single-layer adhesive layer.

(11) The adhesive sheet according to any one of the above (1) to (10), wherein the adhesive layer contains a (meth) acrylic polymer in a proportion of more than 50% by weight of a polymer component contained in the adhesive layer.

(12) The pressure-sensitive adhesive sheet according to the item (11), wherein the (meth) acrylic polymer contains, as monomer components constituting the (meth) acrylic polymer, the following component (a):

an alkyl (meth) acrylate having an alkyl group having 2 to 18 carbon atoms at the ester end.

(13) The adhesive sheet according to the item (11) or (12), wherein the component (A) accounts for about 30 to about 70 wt% of the entire monomer component.

(14) The adhesive sheet according to any one of the above (11) to (13), wherein the (meth) acrylic polymer further contains, as a monomer component constituting the (meth) acrylic polymer, the following component (B): an alicyclic monomer.

(15) The adhesive sheet according to any one of the above (11) to (14), wherein the component (B) is at least 1 selected from the group consisting of cyclopropyl (meth) acrylate, cyclobutyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, cyclooctyl (meth) acrylate, isobornyl (meth) acrylate, and dicyclopentanyl (meth) acrylate.

(16) The adhesive sheet according to any one of the above (11) to (15), wherein the proportion of the component (B) in the entire monomer component is about 20% by weight to about 50% by weight.

(17) The adhesive sheet according to any one of the above (11) to (16), wherein the (meth) acrylic polymer further contains, as a monomer component constituting the (meth) acrylic polymer, the following component (C): a monomer having at least any one of a hydroxyl group and a carboxyl group.

(18) The adhesive sheet according to any one of the above (11) to (17), wherein the proportion of the component (C) in the entire monomer component is about 15% by weight to about 30% by weight.

(19) The adhesive sheet according to any one of the above (11) to (18), wherein the (meth) acrylic polymer further contains a polyfunctional monomer as a monomer component constituting the (meth) acrylic polymer, and the ratio of the polyfunctional monomer to the entire monomer component is about 3% by weight or less.

(20) The adhesive sheet according to any one of the above (11) to (19), wherein the (meth) acrylic polymer is an ultraviolet polymer of the monomer component.

(21) A method for producing the adhesive sheet according to any one of (11) to (20), which comprises forming the adhesive layer by using an adhesive composition containing at least a part of the monomer component in the form of a polymer.

(22) The method for producing a pressure-sensitive adhesive sheet according to the item (21), wherein the forming of the pressure-sensitive adhesive layer comprises applying the pressure-sensitive adhesive composition to a release surface of a release film and drying or curing the pressure-sensitive adhesive composition on the release surface.

(23) The method for producing an adhesive sheet according to the item (21) or (22), wherein the organic solvent content of the adhesive composition is about 5% by weight or less.

(24) The method for producing a pressure-sensitive adhesive sheet according to any one of (21) to (23), wherein the forming of the pressure-sensitive adhesive layer comprises forming the pressure-sensitive adhesive layer by curing a liquid film of the pressure-sensitive adhesive composition between release surfaces of a pair of release films.

(25) An adhesive sheet with a release film, comprising:

the adhesive sheet according to any one of (1) to (20) above, and

a first release film disposed on the first adhesive surface.

(26) An adhesive sheet with a release film, comprising:

the adhesive sheet according to any one of (4) to (20) above,

A first release film disposed on the first adhesive surface, and

and a second release film disposed on the second adhesive surface.

(27) The pressure-sensitive adhesive sheet with a release film according to the above (25) or (26)Wherein a release surface of the first release film in contact with the first adhesive surface has a ten-point average roughness (Rz)_R1) A ten-point average roughness (Rz) of the first adhesive surface_A1) The difference is within about 250 nm.

(28) The pressure-sensitive adhesive sheet with a release film as described in the above (26) or (27), wherein Rz is satisfied_A1＜Rz_R1And Rz_A2＜Rz_R2。

(29) The pressure-sensitive adhesive sheet with a release film according to any one of the above (25) to (28), wherein the first release film contains at least 1 kind of inorganic particles selected from the group consisting of silica, alumina, kaolin, talc, mica and calcium carbonate.

(30) The release film-equipped adhesive sheet according to any one of the items (25) to (29), wherein the first release film has a thickness of about 10 μm or more and about 500 μm or less (preferably about 20 μm or more and about 100 μm or less, more preferably about 25 μm or more and about 80 μm or less).

(31) An adhesive optical member comprising:

the adhesive sheet according to any one of (4) to (20) above, and

and an optical member disposed on the second pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet.

(32) A method for manufacturing an article with an adhesive sheet, comprising:

preparing the pressure-sensitive adhesive sheet with a release film according to any one of (26) to (30) above;

a release surface for peeling the first release film from the first adhesive surface and attaching another release film to the exposed first adhesive surface; and

the second adhesive surface is adhered to an article to be adhered.

(33) The method for producing an article with an adhesive sheet according to the item (32), wherein the other release film is a film having a ten-point average roughness (Rz) of the release surface of the other release film_E1) Greater than the ten-point average roughness (Rz) of the release surface of the first release film in contact with the first adhesive surface_R1) Is/are as followsA film.

Examples

Several examples of the present invention will be described below, but the present invention is not limited to the embodiments shown in the examples.

< preparation of adhesive composition >

(adhesive composition C1)

40 parts by weight of n-butyl acrylate, 41 parts by weight of cyclohexyl acrylate, 19 parts by weight of 4-hydroxybutyl acrylate, 0.05 part by weight of 2, 2-dimethoxy-1, 2-diphenylethan-1-one (product name "Irgacure 651" manufactured by BASF) as a photopolymerization initiator and 0.05 part by weight of 1-hydroxycyclohexylphenylketone (product name "Irgacure 184" manufactured by BASF) were mixed and irradiated with ultraviolet light under a nitrogen atmosphere to prepare a partial polymer (monomer slurry). To the resulting monomer slurry, 0.1 part by weight of 1, 6-hexanediol diacrylate was added and uniformly mixed to prepare adhesive composition C1.

(adhesive compositions C2-C4)

In the preparation of adhesive composition C1, the amount of 1, 6-hexanediol diacrylate added was changed to 0.3 part by weight in adhesive composition C2, 0.05 part by weight in adhesive composition C3, and 0 part by weight in adhesive composition C4. Otherwise, adhesive compositions C2 to C4 were prepared by the same operation as that for the preparation of adhesive composition C1.

The adhesive compositions C1 to C4 were all solvent-free compositions. Specifically, the content of the solvent in each of the adhesive compositions C1 to C4 was less than 5% by weight, more specifically less than 1% by weight.

< production of adhesive sheet >

Preparing: a release film R1 having a release treatment layer obtained from a silicone release treatment agent a1 on one side of a polyethylene terephthalate (PET) film F1 having a thickness of 38 μm and having a ten-point average roughness of 211nm on the release surface (surface of the release treatment layer); a release film R2 having a release treatment layer obtained from a silicone release treatment agent A1 on one side of a PET film F2 having a thickness of 38 μm and having a ten-point average roughness of the release surface of 1610 nm; the PET film F2 had a release-treated layer obtained from a silicone release treating agent a2 on one side, and the release film R3 had a ten-point average roughness of the release surface of 1610 nm. The release surface of the release film R3 was formed so that the peel strength of the release film from the pressure-sensitive adhesive layer was higher than that of the release films R1 and R2. Using these release films, a pressure-sensitive adhesive sheet was produced in the following manner.

The ten-point average roughness of each release surface of the release films R1, R2, and R3 was measured as follows: measured values were obtained in the same manner as the surface smoothness measurement of the first adhesive surface described below except that the back surface (non-release-treated surface) of each release film was disposed in close contact with the slide glass by 1 drop of water dropped on the slide glass s1112no.2 (manufactured by sonlang nit industries) by a dropper.

(example 1)

The pressure-sensitive adhesive composition C1 prepared above was applied to the release surface of the release film R1, and a liquid film of the pressure-sensitive adhesive composition was formed on the release surface. The amount of the adhesive composition applied was adjusted so that the thickness of the adhesive layer finally formed became 50 μm. Then, the liquid film was covered with a release film R3 so that the release surface of the release film R3 was in contact with the liquid film, thereby blocking the liquid film from oxygen. In the state where both surfaces (first and second surfaces) of the liquid film of the adhesive composition C1 were brought into contact with the release surfaces of the release films R1 and R3, respectively, the film was irradiated with a chemical lamp (manufactured by Toshiba, Ltd.) for 360 seconds at an illuminance of 5mW/cm²The liquid film was cured by polymerization reaction with ultraviolet rays to form a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive sheet S1 of example 1 including the pressure-sensitive adhesive layer (i.e., the ultraviolet cured product of the liquid film) was obtained. The psa sheet S1 constitutes a release film R1 used for producing the psa sheet S1, and a psa sheet with a release film in which the release surface of R3 is in contact with the first surface (first psa surface) and the second surface (second psa surface), respectively.

The numerical value of the illuminance is a value measured by an industrial UV detector (product name "UVR-T1" manufactured by TOPCON CORPORATION, light receiving part model number UD-T36) having a peak sensitivity wavelength of about 350 nm.

(examples 2 and 3)

Psa sheets S2 and S3 of examples 2 and 3 were obtained in the same manner as in the preparation of psa sheet S1 of example 1, except that psa compositions C2 and C3 were used instead of psa composition C1, respectively. The pressure-sensitive adhesive sheets S2 and S3 constitute pressure-sensitive adhesive sheets with release films in which the release surfaces of the release films R1 and R3 used for producing the pressure-sensitive adhesive sheets are in contact with the first pressure-sensitive adhesive surface and the second pressure-sensitive adhesive surface, respectively.

Comparative example 1

In the production of the adhesive sheet S2 of example 2, a release film R2 was used in place of the release film R1. That is, the pressure-sensitive adhesive composition C2 was applied to the release surface of the release film R2 to form a liquid film of the pressure-sensitive adhesive composition, and the release film R3 was covered on the liquid film so that the release surface of the release film was in contact with the liquid film. A psa sheet S4 of comparative example 1 was obtained in the same manner as in example 2, except that the psa composition C2 was irradiated with ultraviolet light on the release surfaces where both sides of the liquid film were in contact with the release films R2 and R3, respectively. The psa sheet S4 constitutes a psa sheet with a release film in which the release surfaces of the release films R2 and R3 used for producing the psa sheet S4 are in contact with the first psa surface and the second psa surface, respectively.

Comparative example 2

A psa sheet S5 of comparative example 2 was obtained in the same manner as in the preparation of psa sheet S1 of example 1, except that psa composition C4 was used instead of psa composition C1. The psa sheet S5 constitutes a release film-attached psa sheet having a release film R1 used for producing the psa sheet S5 and a release surface of R3 in contact with the first psa surface and the second psa surface, respectively.

The pressure-sensitive adhesive sheets of the respective examples were stored in the form of the pressure-sensitive adhesive sheet with a release film at 23 ℃ and 50% RH for 7 days after production, and then subjected to the following measurement and test.

< determination of storage modulus >

An adhesive layer having a thickness of about 2mm was prepared by stacking a plurality of adhesive sheets (adhesive layers having a thickness of about 50 μm) according to each example. Clamping and fixing the adhesive with parallel platesThe layer was punched out into a disk-like shape having a diameter of 7.9mm, and dynamic viscoelasticity was measured under the following conditions using a viscoelasticity tester (TA Instruments Co., Ltd., manufactured by Ltd., ARES) to determine a storage modulus (G'₂₃) And storage modulus at 100 ℃ (G'₁₀₀)。

Measurement mode: shear mode

Temperature range: -70 ℃ to 150 DEG C

Temperature increase rate: 5 ℃ per minute

Measurement frequency: 1Hz

< ten-point average roughness of first adhesive surface in initial constitution >

The release film on the second adhesive surface of each adhesive sheet was removed under an atmosphere of 23 ℃ and 50% RH, and the exposed second adhesive surface was adhered to a slide glass s1112no.2 (manufactured by sonlang nit industries). Then, the release film on the first pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet adhered to the slide glass was peeled by hand in the 180-degree direction at a peeling speed of about 10 m/min, and the ten-point average roughness of the first pressure-sensitive adhesive surface exposed by this operation was measured by a surface roughness measuring apparatus of the optical interference system (manufactured by Veeco, Wyko NT-9100). The measurement was performed within 10 minutes after the release film was removed from the first pressure-sensitive adhesive surface. The measurement conditions are as follows.

Area/time of measurement: 622 μm.times.467 μm

(Objective lens: 10 times, FOV (internal lens): 1.0 times)

Measurement mode: VSI (Vertical Scan interference, Vertical scanning type interference)

Back scan (back scan): 5 μm

Measurement distance: 10 μm

Threshold value: 0.1 percent of

Scanning speed: 1 time (Single scan)

The highest peak in the measurement plane was taken from the data set obtained by the measurement, and the level of the peak top was designated as H1. The range of 11 × 11 pixels around H1 was masked, the highest peak was taken except for the masked range, and the peak top level was designated as H2. This operation was repeated to determine H3 to H10.The altitudes from the highest peak to the 10 th peak were obtained in this manner (H1 to H10). In the same manner, the heights of the bottom portions from the lowest bottom to the 10 th bottom in the measurement plane were obtained (L1 to L10). Rz is calculated based on their values using the following formula. In the formula, H_jThe height (elevation) of each peak top, L_jThe depth (elevation) of each valley bottom is shown.

[ number 1]

The measurement was performed 5 times (i.e., N is 5), and the average value of these measurements was obtained.

< ten point average roughness of first adhesive surface after replacement of release film >

(test example 1)

The release film R1 was peeled by hand from the first adhesive surface of the adhesive sheet S1 of example 1 at a peeling speed of about 10 m/min in a 180-degree direction under an atmosphere of 23 ℃ and 50% RH. Immediately after this operation, a 2kg roller was reciprocated 1 time at a moving speed of about 300 mm/min to attach another release film R1 to the exposed first adhesive surface. In this way, the release film R1 for protecting the first pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet of example 1 was replaced (pasted) with another release film R1. After holding the pressure-sensitive adhesive sheet at 23 ℃ and 50% RH for 2 hours, the exchanged release film R1 was peeled off by hand in the 180-degree direction at a peeling speed of about 10 m/min, and the ten-point average roughness of the exposed first pressure-sensitive adhesive surface was measured in the same manner as described above.

(test example 2)

In this test example, the release film R1 on the first pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet S2 of example 2 was replaced with a release film R2. Otherwise, the ten-point average roughness of the first pressure-sensitive adhesive surface exposed by removing the replaced release film R2 was measured by the same operation as in test example 1.

(test example 3)

In this test example, the release film R1 on the first pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet S3 of example 3 was replaced with a release film R2. Otherwise, the ten-point average roughness of the first pressure-sensitive adhesive surface exposed by peeling the replaced release film R2 was measured by the same operation as in test example 1.

(test example 4)

In this test example, the release film R1 on the first pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet S4 of comparative example 1 was replaced with a release film R2. Otherwise, the ten-point average roughness of the first pressure-sensitive adhesive surface exposed by peeling the replaced release film R2 was measured by the same operation as in test example 1.

(test example 5)

In this test example, the release film R2 on the first pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet S4 of comparative example 1 was replaced with a release film R1. Otherwise, the ten-point average roughness of the first pressure-sensitive adhesive surface exposed by peeling the replaced release film R1 was measured by the same operation as in test example 1.

(test example 6)

In this test example, the release film R2 on the first pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet S5 of comparative example 2 was replaced with another release film R2. Otherwise, the ten-point average roughness of the first pressure-sensitive adhesive surface exposed by peeling the replaced release film R2 was measured by the same operation as in test example 1.

Table 1 shows the results obtained.

[ Table 1]

As shown in table 1, it was confirmed that the ten-point average roughness of the first pressure-sensitive adhesive surface was 1000nm or less: by setting the 100 ℃ storage modulus of the pressure-sensitive adhesive layer constituting the first pressure-sensitive adhesive surface to 0.08MPa or more, a decrease in smoothness of the first pressure-sensitive adhesive surface due to replacement of the release film is significantly suppressed. In addition, in the case of manufacturing the pressure-sensitive adhesive sheet S4 having the first pressure-sensitive adhesive surface with low smoothness in the initial configuration, even when the release film on the first pressure-sensitive adhesive surface was changed to a more smooth one thereafter, improvement in smoothness of the first pressure-sensitive adhesive surface was not observed.

Specific examples of the present invention have been described in detail, but these are merely examples and do not limit the claims. The techniques claimed in the claims include those obtained by variously changing or modifying the specific examples shown in the above examples.

Claims (17)

1. An adhesive sheet comprising an adhesive layer,

the adhesive sheet has a first side and a second side,

the first face is a first adhesive face constituted by one surface of the adhesive layer,

the first adhesive surface has a ten-point average roughness of 1000nm or less,

the adhesive layer has a storage modulus at 100 ℃ of 0.08MPa or more,

the adhesive layer has a storage modulus at 23 ℃ of 0.15MPa or more,

the adhesive layer contains a (meth) acrylic polymer in a proportion of more than 50% by weight of a polymer component contained in the adhesive layer,

the (meth) acrylic polymer contains 15 to 30 wt% of a monomer having at least either one of a hydroxyl group and a carboxyl group as a monomer component constituting the (meth) acrylic polymer,

the ten-point average roughness is an average value of absolute values of differences between Yp1 to Yp10 and Yv1 to Yv10, which are obtained by measuring the elevations of the peak top from the highest peak top to the 10 th position, that is, Yp1 to Yp10, and the elevations of the valley bottom from the lowest valley bottom to the 10 th position, that is, Yv1 to Yv10, on a roughness curve obtained by surface roughness measurement,

the 100 ℃ storage modulus of the adhesive layer was determined by: a sample obtained by punching the pressure-sensitive adhesive layer into a disk shape having a diameter of 7.9mm was held and fixed by parallel plates, and dynamic viscoelasticity was measured under the following conditions by a viscoelasticity tester ARES manufactured by TA Instruments Co., Ltd. to obtain a storage modulus G'100 at 100 ℃,

measurement mode: shear mode

Temperature range: -70 ℃ to 150 DEG C

Temperature increase rate: 5 ℃ per minute

Measurement frequency: 1 Hz.

2. The adhesive sheet according to claim 1, wherein the ratio of the 100 ℃ storage modulus to the 23 ℃ storage modulus of the adhesive layer is 35% or more.

3. The adhesive sheet according to claim 1 or 2, wherein the adhesive layer has a storage modulus at 23 ℃ of less than 0.30 MPa.

4. The adhesive sheet according to claim 1, wherein the (meth) acrylic polymer comprises, as a monomer component constituting the (meth) acrylic polymer, an alkyl (meth) acrylate having an alkyl group having 2 to 18 carbon atoms at an ester end.

5. The adhesive sheet according to claim 4, wherein the alkyl (meth) acrylate having an alkyl group with 2 to 18 carbon atoms at an ester end accounts for 30% by weight or more and 70% by weight or less of the entire monomer component.

6. The adhesive sheet according to claim 1, wherein the (meth) acrylic polymer further comprises an alicyclic monomer as a monomer component constituting the (meth) acrylic polymer.

7. The adhesive sheet according to claim 6, wherein the alicyclic monomer accounts for 20% by weight or more and 50% by weight or less of the entire monomer component.

8. The adhesive sheet according to claim 1, wherein the (meth) acrylic polymer further comprises a polyfunctional monomer as a monomer component constituting the (meth) acrylic polymer,

the proportion of the polyfunctional monomer in the whole monomer component is 3 wt% or less.

9. The adhesive sheet according to claim 1, wherein the (meth) acrylic polymer is an ultraviolet polymer of the monomer component.

10. The adhesive sheet according to claim 1 or 2, wherein the second side is a second adhesive side.

11. The adhesive sheet according to claim 10, wherein the second adhesive surface has a ten-point average roughness of 2000nm or less.

12. The adhesive sheet according to claim 11, wherein the second adhesive surface has a ten-point average roughness of 1000nm or less.

13. The adhesive sheet according to claim 10, wherein any one of a ten-point average roughness of the first adhesive surface and a ten-point average roughness of the second adhesive surface is 500nm or less.

14. The adhesive sheet according to claim 10, wherein the second adhesive surface is constituted by the other surface of the adhesive layer.

15. An adhesive sheet with a release film, comprising:

the adhesive sheet according to any one of claims 1 to 14, and

a first release film disposed on the first adhesive surface.

16. The release film-equipped adhesive sheet according to claim 15, wherein the second side is a second adhesive side,

the release film-attached pressure-sensitive adhesive sheet further comprises a second release film disposed on the second pressure-sensitive adhesive surface.

17. The release film-equipped adhesive sheet according to claim 15 or 16, wherein the first release film has a release surface in contact with the first adhesive surface,

the difference between the ten-point average roughness of the release surface and the ten-point average roughness of the first adhesive surface is within 250 nm.

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