Adhesive sheet and its use

Abstract

To provide an adhesive sheet that can form a joint with high deformation resistance and high impact resistance.SOLUTION: The present invention provides an adhesive sheet 2 which has an adhesive layer 10. In this adhesive sheet, the elastic modulus as determined by a tensile test is 3.0 MPa or more, and the impact resistance as determined by a shear impact test is 2.0 J / (10 mm)2 or more.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive sheet, a film member with a pressure-sensitive adhesive sheet, and a method for producing a laminate. [Background technology]

[0002] Generally, pressure-sensitive adhesives (also called pressure-sensitive adhesives; the same applies hereinafter) are in a soft solid (viscoelastic) state in a temperature range around room temperature, and have the property of easily adhering to an adherend when pressure is applied. Utilizing these properties, pressure-sensitive adhesives are widely used in a variety of fields, typically in the form of pressure-sensitive adhesive sheets containing a pressure-sensitive adhesive layer. Patent Document 1 is an example of a technical document relating to pressure-sensitive adhesive sheets. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-017113 Summary of the Invention [Problem to be solved by the invention]

[0004] Pressure-sensitive adhesives are required to have various properties depending on their application. Some of these properties are difficult to achieve at a high level, as an attempt to improve one property tends to decrease the other. Examples of properties that are difficult to achieve at the same time include the property of being resistant to deformation under stress (hereinafter also referred to as "deformation resistance") and the property of being able to withstand impact and maintain adhesion to the adherend (hereinafter also referred to as "impact resistance").

[0005] Therefore, an object of the present invention is to provide a pressure-sensitive adhesive sheet capable of forming a bond with high deformation resistance and high impact resistance. Another object of the present invention is to provide a film member with a pressure-sensitive adhesive sheet configured to include the pressure-sensitive adhesive sheet. Yet another object of the present invention is to provide a method for manufacturing a laminate using the pressure-sensitive adhesive sheet. [Means for solving the problem]

[0006] According to this specification, there is provided a pressure-sensitive adhesive sheet including a pressure-sensitive adhesive layer, which has the following properties (a) and (b): (a) The modulus of elasticity measured by the following tensile test is 3.0 MPa or more. (b) Impact resistance of 2.0 J / (10 mm) as measured by the following shear impact test 2 That's all. [Tensile test] The adhesive layer was exposed to an illumination intensity of 300 mW / cm 2 , cumulative light intensity 3000mJ / cm 2 After aging at 50°C for 48 hours, the pressure-sensitive adhesive layer is cut into a size of 10 mm wide and 150 mm long to prepare a test piece. A tensile test is performed on the test piece using a tensile tester under conditions of 23°C and 50% RH, with a chuck distance of 120 mm and a tensile speed of 50 mm / min, to obtain a stress-displacement curve (hereinafter also referred to as "SS curve"), and the elastic modulus [MPa] (hereinafter also referred to as tensile elastic modulus) is calculated from the initial slope. [Shear impact test] A shear impact test was performed using a pendulum-type adhesive shear impact tester based on JIS K6855. The measurement sample was prepared by bonding the first surface of a 10 mm square pressure-sensitive adhesive layer to the center of a 25 mm square, 1.7 mm thick chemically strengthened glass plate, and then bonding the second surface of the pressure-sensitive adhesive layer to the center of a 40 mm square stainless steel plate (SUS304BA plate) under pressure of 5 N for 10 seconds, followed by autoclaving (50°C, 0.5 MPa, 15 minutes), and then heating at an illuminance of 300 mW / cm from the glass plate side. 2 , cumulative light intensity 3000mJ / cm 2 After irradiating with ultraviolet light under the conditions above, the film is aged at 50°C for 48 hours before use. The measurement sample was fixed with the stainless steel plate facing downwards, and the impact resistance [J / (10 mm)] was measured by measuring the absorbed energy [J] when hitting the outer periphery of the glass plate with a hammer at a hammer energy of 2.75 J and a hammer speed (impact speed) of 3.5 m / s under an environment of 23°C and 50% RH. 2 ] is required.

[0007] By satisfying the above property (a), the pressure-sensitive adhesive layer can exhibit high deformation resistance, for example, when the pressure-sensitive adhesive sheet is in use. A pressure-sensitive adhesive sheet that satisfies the above properties (a) and (b) can form a bond that is highly resistant to deformation and highly resistant to impact, and therefore can be preferably used for the purpose of joining or fixing members, for example.

[0008] The present specification also provides a pressure-sensitive adhesive sheet including a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer containing a polymer (A) and a photoreactive monomer (B). In some embodiments of the pressure-sensitive adhesive sheet, the photoreactive monomer (B) includes a compound B1 having a ring structure and two or more ethylenically unsaturated groups in the molecule. The compound B1 preferably has a molecular weight per ethylenically unsaturated group of 100 g / mol or more. A pressure-sensitive adhesive sheet including such a pressure-sensitive adhesive layer can suitably form a bond that is highly resistant to deformation and impact.

[0009] The pressure-sensitive adhesive sheet according to any of the embodiments disclosed herein may satisfy the following characteristic (c): A pressure-sensitive adhesive sheet satisfying characteristic (c) may be preferably used for purposes such as joining or fixing members. (c) The peel strength measured by the following peel test is 1.0 N / 10 mm or more. [Peel test] The first surface of the pressure-sensitive adhesive layer was pressed against a glass plate by rolling a 2 kg rubber roller back and forth once, and the pressure-sensitive adhesive layer was then autoclaved (50°C, 0.5 MPa, 15 minutes). After that, the pressure-sensitive adhesive layer was exposed to light from the glass plate side at an illuminance of 300 mW / cm. 2 , cumulative light intensity 3000mJ / cm 2After aging at 50°C for 48 hours, the test piece is peeled from the glass plate using a tensile tester at a peel angle of 180° and a pulling rate of 60 mm / min in an environment of 23°C and 50% RH, and the peel strength is measured.

[0010] According to this specification, there is provided a film member with a pressure-sensitive adhesive sheet, comprising any of the pressure-sensitive adhesive sheets disclosed herein and a film member bonded to the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet. The film member with the pressure-sensitive adhesive sheet can suitably form a bond that is highly resistant to deformation and impact.

[0011] This specification provides a method for producing a laminate, which comprises, in this order, laminating any of the pressure-sensitive adhesive sheets disclosed herein to an adherend, and irradiating the pressure-sensitive adhesive sheet with ultraviolet light to photocure the pressure-sensitive adhesive layer. This method makes it possible to produce a laminate that favorably combines impact resistance and high deformation resistance.

[0012] In addition, any suitable combination of the above elements may also be included in the scope of the invention for which patent protection is sought through this patent application. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view schematically illustrating the configuration of a pressure-sensitive adhesive sheet according to one embodiment. [Figure 2] FIG. 10 is a cross-sectional view schematically illustrating the configuration of a pressure-sensitive adhesive sheet according to another embodiment. [Figure 3] 1 is a cross-sectional view schematically showing a film member with a pressure-sensitive adhesive sheet according to one embodiment, in which the pressure-sensitive adhesive sheet is attached to a film member. DETAILED DESCRIPTION OF THE INVENTION

[0014] Preferred embodiments of the present invention are described below. Matters necessary for carrying out the present invention other than those specifically mentioned in this specification can be understood by those skilled in the art based on the teachings for carrying out the invention described in this specification and the common general technical knowledge at the time of filing. The present invention can be carried out based on the contents disclosed in this specification and the common general technical knowledge in the relevant field. Furthermore, in the following drawings, components and parts that perform the same function may be denoted by the same reference numerals, and redundant explanations may be omitted or simplified. Furthermore, the embodiments shown in the drawings are schematic for the purpose of clearly explaining the present invention, and do not necessarily accurately represent the size or scale of the actual product provided.

[0015] In this specification, "acrylic polymer" refers to a polymer derived from a monomer component containing more than 50% by weight of an acrylic monomer, and is also referred to as an acrylic polymer. The acrylic monomer refers to a monomer having at least one (meth)acryloyl group in one molecule. In addition, in this specification, "(meth)acryloyl" refers to acryloyl and methacryloyl in a comprehensive sense. Similarly, "(meth)acrylate" refers to acrylate and methacrylate, and "(meth)acrylic" refers to acrylic and methacrylic in a comprehensive sense. In this specification, "mass" and "weight" have the same meaning.

[0016] In this specification, a "photoreactive monomer" is a compound having at least one functional group (photoreactive functional group) in the molecule that can undergo a reaction upon irradiation with light, and typically a compound having at least one ethylenically unsaturated group in the molecule as the photoreactive functional group. The photoreactive monomer referred to here may be any compound that can undergo a reaction as a monomer, and may itself be, for example, a polymer such as an oligomer or polymer (for example, a polymer having at least one ethylenically unsaturated group in the molecule).

[0017] <Adhesive sheet configuration example> FIG. 1 shows an example of the configuration of a pressure-sensitive adhesive sheet disclosed herein. This pressure-sensitive adhesive sheet 1 is configured as a single-sided pressure-sensitive adhesive sheet (a single-sided pressure-sensitive adhesive sheet with a support) including a pressure-sensitive adhesive layer 10, one surface 10A of which serves as the surface to be attached to an adherend (adhesive surface), and a support 20 laminated on the other surface 10B of the pressure-sensitive adhesive layer 10. The pressure-sensitive adhesive layer 10 is bonded to one surface 20A of the support 20. For example, a resin film such as a polyester film can be used as the support 20. The support 20 may also be an optical film such as a polarizing plate. In the example shown in FIG. 1, the pressure-sensitive adhesive layer 10 has a single-layer structure. Before use (before attachment to an adherend), the pressure-sensitive adhesive sheet 1 may be in the form of a release-liner-attached pressure-sensitive adhesive sheet 50, in which the adhesive surface 10A is protected by a release liner 30, at least the pressure-sensitive adhesive layer side of which serves as a release surface (release surface), as shown in FIG. 1, for example. Alternatively, the second surface 20B of the support 20 (the surface opposite to the first surface 20A, also called the back surface) may be the release surface, and the adhesive surface 10A may be protected by being wound or laminated so that the adhesive surface 10A abuts against the second surface 20B of the support 20.

[0018] The release liner is not particularly limited, and examples thereof include release liners in which the surface of a liner substrate such as a resin film or paper has been release-treated, and release liners made of low-adhesion materials such as fluorine-based polymers (e.g., polytetrafluoroethylene) and polyolefin-based resins (e.g., polyethylene and polypropylene). For the release treatment, for example, a silicone-based or long-chain alkyl-based release treating agent can be used. In some embodiments, a release-treated resin film can be preferably used as the release liner.

[0019] The PSA sheet disclosed herein may be in the form of a support-less double-sided PSA sheet comprising a PSA layer. As shown in Figure 2, the support-less double-sided PSA sheet 2 may, before use, be in a form in which each side 10A, 10B of the PSA layer 10 is protected by release liners 31, 32, with at least the PSA layer side serving as a releasable surface (release surface). Alternatively, the back surface of the release liner 31 (the surface opposite the PSA side) may be the release surface, and the PSA surface 10B may be protected by being wound or laminated so that the PSA surface 10B abuts against the back surface of the release liner 31. Such a support-less double-sided PSA sheet may be used, for example, by bonding a support to either surface of the PSA layer. The pressure-sensitive adhesive sheet disclosed herein may also be in the form of a supported, double-sided pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is laminated on each of one surface and the other surface of a sheet-like support. The support in such a pressure-sensitive adhesive sheet may be, for example, a resin film such as a polyester film, or an optical film such as a polarizing plate.

[0020] The pressure-sensitive adhesive sheet disclosed herein may be a component of a film member with a pressure-sensitive adhesive sheet, in which a film member is bonded to one surface of a pressure-sensitive adhesive layer. For example, the pressure-sensitive adhesive sheet 1 shown in Fig. 1 may be a component of a film member with a pressure-sensitive adhesive sheet 100, in which a film member 70 is bonded to one surface 10A of a pressure-sensitive adhesive layer 10, as shown in Fig. 3. The film member may be, for example, an electromagnetic wave-transmitting metallic gloss member such as that described in JP 2018-69462 A, a polarizing plate, or other optical film.

[0021] <Characteristics of adhesive sheets> (tensile modulus) In the pressure-sensitive adhesive sheet disclosed herein, the pressure-sensitive adhesive layer (which may be a pressure-sensitive adhesive layer formed using any of the pressure-sensitive adhesive compositions disclosed herein) preferably has a tensile modulus of 3.0 MPa or more. The tensile modulus is measured by the tensile test described above, more specifically, by the method described in the Examples below. A pressure-sensitive adhesive layer with a higher tensile modulus tends to exhibit better deformation resistance. The pressure-sensitive adhesive sheet with a high tensile modulus can be preferably used for purposes such as joining or fixing members. For example, in a laminate in which a member and an adherend are joined via a pressure-sensitive adhesive layer, high deformation resistance of the pressure-sensitive adhesive layer can be useful for accurately maintaining the relative position of the member with respect to the adherend. Furthermore, in a laminate in which a film member and an adherend are joined via a pressure-sensitive adhesive layer, high deformation resistance of the pressure-sensitive adhesive layer can be useful for suppressing changes in the appearance of the laminate caused by local pressure applied from the film member side. In a laminate in which the adherend is a transparent rigid member (e.g., a glass member), suppressing changes in appearance visible from the adherend side is particularly meaningful.

[0022] In some preferred embodiments of the pressure-sensitive adhesive sheet, the tensile modulus may be, for example, 5.0 MPa or more, 7.0 MPa or more, 10.0 MPa or more, 15.0 MPa or more, or 20.0 MPa or more. An increase in the tensile modulus tends to improve deformation resistance. There is no particular upper limit to the tensile modulus. From the viewpoint of easily achieving a balance with other properties (e.g., one or more properties selected from impact resistance, peel strength, haze value, etc.), the tensile modulus is usually advantageously 150 MPa or less, preferably 120 MPa or less, and may be 100 MPa or less, 80 MPa or less, or 60 MPa or less. The tensile modulus can be adjusted by selecting the composition of the pressure-sensitive adhesive layer, etc.

[0023] In the tensile test, the treatment of irradiating the pressure-sensitive adhesive layer with ultraviolet light is preferably carried out while the pressure-sensitive adhesive layer is sandwiched between transparent release liners. From the viewpoint of transparency, a polyester resin film (e.g., a release-treated polyethylene terephthalate resin (PET) film) having at least one surface treated for release can be preferably used as the release liner. Although not particularly limited, the thickness of the release liner may be, for example, about 10 μm to 125 μm, 10 μm to 75 μm, or 20 μm to 50 μm.

[0024] The thickness of the test piece used in the tensile test may be similar to or different from the thickness of the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet disclosed herein. For example, when the thickness of the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet is relatively small, the test piece may be prepared to have a thickness of 5 μm or more (e.g., approximately 5 μm to 200 μm) for the purpose of improving operability, and the result obtained by performing the tensile test on the test piece may be used as the tensile modulus of the pressure-sensitive adhesive layer. The thickness of the test piece can be adjusted, for example, by appropriately overlapping the pressure-sensitive adhesive layer before UV irradiation. Alternatively, a test piece having a thickness that facilitates tensile testing may be prepared using the same pressure-sensitive adhesive composition as that used to form the pressure-sensitive adhesive layer to be measured, and the result obtained by performing the tensile test on the test piece may be used as the tensile modulus of the pressure-sensitive adhesive layer. The tensile test may be performed, for example, using a test piece having a thickness of approximately 10 μm to 50 μm (preferably, approximately 15 μm to 25 μm).

[0025] (Impact resistance) The adhesive sheet disclosed herein has an impact resistance of 2.0 J / (10 mm). 2or more. The impact resistance is measured by the shear impact test described above, more specifically, by the method described in the Examples below. A highly impact-resistant PSA sheet can form a highly reliable bond. This can be an advantageous feature for PSA sheets used, for example, for joining or fixing components. Even when subjected to an impact due to, for example, a drop or a collision, such a PSA sheet can withstand the impact and maintain good bonding between the component and the adherend.

[0026] In some preferred embodiments of the PSA sheet, the impact resistance is, for example, 2.1 J / (10 mm) 2 It may be more than 2.3J / (10mm) 2 More than 2.5J / (10mm) is also acceptable. 2 More than 2.7J / (10mm) is also acceptable. 2 More than 3.0J / (10mm) is also acceptable. 2 The pressure-sensitive adhesive sheet disclosed herein has an impact resistance of 3.3 J / (10 mm) or more. 2 or more than 3.5J / (10mm) 2 The above embodiment can also be preferably implemented. The upper limit of the impact resistance is not particularly limited. From the viewpoint of easily balancing with other properties, the impact resistance is, for example, 20 J / (10 mm) 2 May be less than 15J / (10mm) 2 Less than 10J / (10mm) is also acceptable. 2 Less than 8.0J / (10mm) is also acceptable. 2 But 6.0J / (10mm) 2 The impact resistance can be adjusted by selecting the composition, thickness, etc. of the pressure-sensitive adhesive layer.

[0027] The PSA sheets disclosed herein include embodiments in which there is no limitation on the tensile modulus, and in such embodiments, the PSA sheets are not limited to those that satisfy the above-mentioned tensile modulus.Similarly, the PSA sheets disclosed herein include embodiments in which there is no limitation on the impact resistance, and in such embodiments, the PSA sheets are not limited to those that satisfy the above-mentioned impact resistance.

[0028] (peel strength) The peel strength of the pressure-sensitive adhesive sheet disclosed herein is not particularly limited and can be set according to the purpose. The peel strength is measured by the peel test described above, more specifically, by the method described in the Examples below. In some embodiments, the peel strength may be, for example, 0.5 N / 10 mm or more. From the viewpoint of bonding reliability, it is preferably 1.0 N / 10 mm or more, more preferably 1.5 N / 10 mm or more, and may be 2.0 N / 10 mm or more, 2.2 N / 10 mm or more, or 2.3 N / 10 mm or more. Furthermore, from the viewpoint of easily balancing other properties, the peel strength may be, for example, 10 N / 10 mm or less, 8.0 N / 10 mm or less, 6.0 N / 10 mm or less, 5.0 N / 10 mm or less, or 4.0 N / 10 mm or less. The peel strength can be adjusted by selecting the composition, thickness, etc. of the pressure-sensitive adhesive layer.

[0029] (Haze value) In the pressure-sensitive adhesive sheet disclosed herein, the haze value of the pressure-sensitive adhesive layer is not particularly limited. When transparency is required for the pressure-sensitive adhesive layer, the haze value of the pressure-sensitive adhesive layer may be, for example, 10% or less, 5.0% or less, 3.0% or less, or 1.0% or less. Non-limiting examples of usage modes requiring transparency for the pressure-sensitive adhesive layer include usage modes in which a member is bonded to a transparent adherend via the pressure-sensitive adhesive layer, and the member is visible through the pressure-sensitive adhesive layer from the adherend side, and usage modes in which a pressure-sensitive adhesive sheet having a support is bonded to a transparent adherend, and the support is visible through the pressure-sensitive adhesive layer from the adherend side. In some embodiments, the haze value of the pressure-sensitive adhesive layer may be less than 1.0%, less than 0.7%, or 0.5% or less (e.g., 0 to 0.5%).

[0030] Here, the "haze value" refers to the ratio of diffuse transmitted light to total transmitted light when visible light is irradiated onto the object to be measured. It is also called the cloudiness value. The haze value can be expressed by the following formula: Th[%]=Td / Tt×100 In the above formula, Th is the haze value [%], Td is the scattered light transmittance, and Tt is the total light transmittance.

[0031] The haze value was measured at an illumination intensity of 300 mW / cm 2 , cumulative light intensity 3000mJ / cm 2 The pressure-sensitive adhesive layer is irradiated with ultraviolet light under the conditions of (a) and (b) and aged at 50°C for 48 hours, and the resulting sample is used as a measurement sample, and the haze value can be measured using a haze meter (for example, "MR-100" manufactured by Murakami Color Research Laboratory). The haze value can be adjusted, for example, by selecting the composition and thickness of the pressure-sensitive adhesive layer. Note that the treatment of irradiating the pressure-sensitive adhesive layer with ultraviolet light is preferably carried out in a state where the pressure-sensitive adhesive layer is sandwiched between transparent release liners (for example, release-treated PET films), as in the tensile test for measuring the tensile modulus described above.

[0032] <Adhesive layer> The pressure-sensitive adhesive sheet in the technology disclosed herein (including pressure-sensitive adhesive sheets, film members with pressure-sensitive adhesive sheets, and laminate manufacturing methods; the same applies hereinafter) includes a pressure-sensitive adhesive layer. The configuration of the pressure-sensitive adhesive layer can be selected so as to form a bond that is highly resistant to deformation and impact.

[0033] (Polymer (A)) In some embodiments, the pressure-sensitive adhesive layer contains a polymer (A). Examples of materials that can be used as the polymer (A) include polymers that exhibit rubber elasticity at room temperature, such as acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, and fluorine-based polymers, which are well known in the field of pressure-sensitive adhesives. These can be used alone or in combination of two or more.

[0034] The weight proportion of polymer (A) in the total weight of the pressure-sensitive adhesive layer is usually 40% by weight or more, preferably 50% by weight or more, or may be 60% by weight or more, or may be 70% by weight or more, from the viewpoint of impact resistance, etc. The weight proportion of polymer (A) in the total weight of the pressure-sensitive adhesive layer is typically less than 100% by weight, and from the viewpoint of easily adjusting the balance of properties, it is usually advantageous to be 95% by weight or less, preferably 92% by weight or less, or may be 90% by weight or less, or may be 87% by weight or less.

[0035] An acrylic polymer is a suitable example of the polymer (A). The pressure-sensitive adhesive layer in the technology disclosed herein may be an acrylic pressure-sensitive adhesive layer containing an acrylic polymer as a base polymer (the main component of the polymer components, i.e., a component accounting for more than 50% by weight). The acrylic polymer (hereinafter sometimes referred to as "acrylic polymer (A)") as the polymer (A) is preferably an acrylic polymer composed of a monomer component containing 40% by weight or more of a (meth)acrylic acid alkyl ester having a linear or branched alkyl group having from 1 to 20 carbon atoms at the ester terminal. Hereinafter, a (meth)acrylic acid alkyl ester having an alkyl group having from X to Y carbon atoms at the ester terminal will be referred to as "(meth)acrylic acid C X-Y It is sometimes referred to as "alkyl ester."

[0036] In some embodiments, (meth)acrylic acid C is the total monomer component of the acrylic polymer (A). 1-20 The proportion of alkyl ester is preferably more than 40% by weight, since this makes it easier to balance the properties, and may be, for example, 45% by weight or more, 50% by weight or more, 55% by weight or more, or 60% by weight or more. 1-20The proportion of alkyl esters may be 100% by weight, but is usually suitably 98% by weight or less, for example, 95% by weight or less, or 90% by weight or less, in order to easily balance the properties. In some embodiments, the proportion of C in the total monomer components of the acrylic polymer (A) is 1-20 From the viewpoint of improving the cohesion of the pressure-sensitive adhesive layer, the proportion of the (meth)acrylic acid alkyl ester may be, for example, 85% by weight or less, 80% by weight or less, 75% by weight or less, 70% by weight or less, 65% by weight or less, or 60% by weight or less.

[0037] (Meth)acrylic acid C 1-20 Non-limiting examples of alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and isopropyl (meth)acrylate. Examples of the acrylate include isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate.

[0038] Among these, at least (meth)acrylic acid C 4-20 It is preferable to use alkyl esters, and at least (meth)acrylic acid C 4-18 It is more preferable to use alkyl esters. Particularly preferred (meth)acrylic acid C 4-18Examples of alkyl esters include n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA). (Meth)acrylic acid C that can be preferably used 4-20 Other specific examples of alkyl esters include isononyl acrylate, n-butyl methacrylate (BMA), 2-ethylhexyl methacrylate (2EHMA), isostearyl acrylate (iSTA), etc. 4-20 The alkyl esters can be used alone or in combination of two or more.

[0039] The monomer component preferably contains, for example, one or both of n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA). In some embodiments, the monomer component preferably contains at least BA. Here, examples of the monomer component containing at least BA include a monomer component containing BA but not 2EHA, and a monomer component containing BA and 2EHA, where the content of 2EHA is less than the content of BA (for example, the content of 2EHA is less than 0.5 or 0.3 times the content of BA).

[0040] In some embodiments, the monomer component constituting the acrylic polymer (A) is (meth)acrylic acid C 4-18 The monomer component may contain 40% by weight or more of alkyl ester. 4-18 The proportion of alkyl ester may be, for example, 50% by weight or more, 60% by weight or more, or 65% by weight or more. In addition, from the viewpoint of enhancing the cohesiveness of the adhesive layer, (meth)acrylic acid C in the monomer components 4-18 The proportion of alkyl ester is usually suitably 99.5% by weight or less, and may be 95% by weight or less, 85% by weight or less, or 75% by weight or less.

[0041] The monomer components constituting the acrylic polymer (A) may contain, in addition to the (meth)acrylic acid alkyl ester, other monomers (copolymerizable monomers) copolymerizable with the (meth)acrylic acid alkyl ester, as necessary. Suitable copolymerizable monomers include monomers having polar groups (e.g., carboxyl groups, hydroxyl groups, nitrogen atom-containing rings, etc.) and monomers whose homopolymers have relatively high glass transition temperatures (e.g., 10°C or higher). Monomers having polar groups can be useful for introducing crosslinking points into the acrylic polymer (A) or for increasing the cohesive strength of the adhesive. The copolymerizable monomers may be used alone or in combination of two or more.

[0042] Non-limiting examples of copolymerizable monomers include the following: Carboxy group-containing monomers: for example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc. Acid anhydride group-containing monomers: for example, maleic anhydride, itaconic anhydride. Hydroxyl group-containing monomers: for example, hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. Monomers containing a sulfonic acid group or a phosphoric acid group: for example, styrenesulfonic acid, allylsulfonic acid, sodium vinylsulfonate, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid, 2-hydroxyethyl acryloylphosphate, etc. Epoxy group-containing monomers: for example, epoxy group-containing acrylates such as glycidyl (meth)acrylate and 2-ethyl (meth)acrylate glycidyl ether, allyl glycidyl ether, glycidyl (meth)acrylate, etc. Cyano group-containing monomers: for example, acrylonitrile, methacrylonitrile, etc. Isocyanate group-containing monomers: for example, 2-isocyanatoethyl (meth)acrylate. Amide group-containing monomers: for example, (meth)acrylamide; N,N-dialkyl(meth)acrylamides such as N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, and N,N-di(t-butyl)(meth)acrylamide; N-alkyl(meth)acrylamides such as N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, and Nn-butyl(meth)acrylamide; N-vinylcarboxylic acid amides such as N-vinylacetamide; monomers having a hydroxyl group and an amide group, for example, N-(2-hydroxyethyl)(meth)acrylamide N-hydroxyalkyl (meth)acrylamides such as N-(2-hydroxypropyl) (meth)acrylamide, N-(1-hydroxypropyl) (meth)acrylamide, N-(3-hydroxypropyl) (meth)acrylamide, N-(2-hydroxybutyl) (meth)acrylamide, N-(3-hydroxybutyl) (meth)acrylamide, and N-(4-hydroxybutyl) (meth)acrylamide; monomers having an alkoxy group and an amide group, for example, N-alkoxyalkyl (meth)acrylamides such as N-methoxymethyl (meth)acrylamide, N-methoxyethyl (meth)acrylamide, and N-butoxymethyl (meth)acrylamide; and others such as N,N-dimethylaminopropyl (meth)acrylamide and N-(meth)acryloylmorpholine. Amino group-containing monomers: for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate. Monomers having an epoxy group: for example, glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, allyl glycidyl ether. Monomers having a nitrogen atom-containing ring: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, N-vinylisothiazole, N-vinylpyridazine, and the like (for example, lactams such as N-vinyl-2-caprolactam). Monomers having a succinimide skeleton: for example, N-(meth)acryloyloxymethylene succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, N-(meth)acryloyl-8-oxyhexamethylene succinimide, and the like. Maleimides: for example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, etc. Itaconimides: for example, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide, and the like. Aminoalkyl (meth)acrylates: for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate. Alkoxy group-containing monomers: for example, alkoxyalkyl (meth)acrylates (alkoxyalkyl (meth)acrylates) such as 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, and ethoxypropyl (meth)acrylate; alkoxyalkylene (meth)acrylates (for example, alkoxypolyalkylene glycol (meth)acrylates) such as methoxyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate. Alkoxysilyl group-containing monomers: for example, alkoxysilyl group-containing (meth)acrylates such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane; and alkoxysilyl group-containing vinyl compounds such as vinyltrimethoxysilane and vinyltriethoxysilane. Vinyl esters: for example, vinyl acetate, vinyl propionate, etc. Vinyl ethers: for example, vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether. Aromatic vinyl compounds: for example, styrene, α-methylstyrene, vinyltoluene, etc. Olefins: for example, ethylene, butadiene, isoprene, isobutylene, etc. (Meth)acrylic acid esters having an alicyclic hydrocarbon group: for example, (meth)acrylates containing an alicyclic hydrocarbon group such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and adamantyl (meth)acrylate. (Meth)acrylic acid esters having an aromatic hydrocarbon group: for example, (meth)acrylates containing an aromatic hydrocarbon group such as phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate. Other examples include heterocyclic ring-containing (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate, halogen atom-containing (meth)acrylates such as vinyl chloride and fluorine atom-containing (meth)acrylates, silicon atom-containing (meth)acrylates such as silicone (meth)acrylate, and (meth)acrylic acid esters obtained from terpene compound derivative alcohols.

[0043] When such a copolymerizable monomer is used, its amount is not particularly limited, but is usually 0.01% by weight or more of the total monomer components. From the viewpoint of better demonstrating the effect of using the copolymerizable monomer, the amount of the copolymerizable monomer used may be 0.1% by weight or more, or even 0.5% by weight or more of the total monomer components. Furthermore, from the viewpoint of easily balancing the adhesive properties, the amount of the copolymerizable monomer used is usually 50% by weight or less of the total monomer components, and preferably 40% by weight or less.

[0044] In some embodiments, the monomer component constituting the acrylic polymer (A) may contain a monomer having a nitrogen atom. The use of a monomer having a nitrogen atom can increase the cohesive strength of the pressure-sensitive adhesive and favorably improve the peel strength after photocuring. A suitable example of the monomer having a nitrogen atom is a monomer having a nitrogen atom-containing ring. The monomer having a nitrogen atom-containing ring can be one of those exemplified above, and for example, a monomer represented by the general formula (1): [ka] In the general formula (1), N-vinyl cyclic amides represented by the formula 1 is a divalent organic group, a specific example of which is -(CH2) nHere, n is an integer of 2 to 7 (preferably 2, 3, or 4). Of these, N-vinyl-2-pyrrolidone can be preferably used. Other suitable examples of monomers having a nitrogen atom include amide group-containing monomers such as (meth)acrylamide.

[0045] The amount of the nitrogen atom-containing monomer (preferably the nitrogen atom-containing ring-containing monomer) used is not particularly limited and may be, for example, 1% by weight or more, 3% by weight or more, or even 5% by weight or more, or 7% by weight or more of the total monomer components. In one embodiment, the amount of the nitrogen atom-containing monomer used may be 10% by weight or more, 15% by weight or more, or even 20% by weight or more of the total monomer components. Furthermore, the amount of the nitrogen atom-containing monomer used is suitably, for example, 40% by weight or less of the total monomer components, and may be 35% by weight or less, 30% by weight or less, or 25% by weight or less. In another embodiment, the amount of the nitrogen atom-containing monomer used may be, for example, 20% by weight or less, or 15% by weight or less of the total monomer components.

[0046] In some embodiments, the monomer components constituting the acrylic polymer (A) may contain a hydroxyl group-containing monomer. The use of a hydroxyl group-containing monomer allows for favorable adjustment of the cohesive strength and degree of crosslinking (e.g., crosslinking with an isocyanate crosslinking agent) of the PSA. When a hydroxyl group-containing monomer is used, the amount used is not particularly limited and may be, for example, 0.01 wt% or more, 0.1 wt% or more, 0.5 wt% or more, 1 wt% or more, 5 wt% or more, or 10 wt% or more of the total monomer components. Furthermore, from the viewpoint of suppressing the water absorption of the PSA layer, in some embodiments, the amount of the hydroxyl group-containing monomer used is suitably, for example, 40 wt% or less of the total monomer components, or alternatively, 30 wt% or less, 25 wt% or less, or 20 wt% or less. In another embodiment, the amount of the hydroxyl group-containing monomer used may be, for example, 15 wt% or less, 10 wt% or less, or 5 wt% or less of the total monomer components.

[0047] In some embodiments, the proportion of the carboxyl group-containing monomer in the monomer components of the acrylic polymer (A) may be, for example, 2 wt. % or less, 1 wt. % or less, or 0.5 wt. % or less (e.g., less than 0.1 wt. %). The acrylic polymer (A) may be substantially free of carboxyl group-containing monomers as a monomer component. Here, "substantially free of carboxyl group-containing monomers" means that carboxyl group-containing monomers are not used, at least intentionally. A pressure-sensitive adhesive layer containing an acrylic polymer (A) with a limited amount of carboxyl group-containing monomers as described above is preferred from the viewpoint of preventing metal corrosion. A pressure-sensitive adhesive sheet having such a pressure-sensitive adhesive layer may also be preferably used in an embodiment in which the pressure-sensitive adhesive layer is in contact with an adherend containing a metal material and / or a support (which may be a metal foil or a support film containing a metal material).

[0048] In some embodiments, the monomer component constituting the acrylic polymer (A) may contain an alicyclic hydrocarbon group-containing (meth)acrylate. This can increase the cohesive strength of the pressure-sensitive adhesive and improve peel strength after photocuring. Examples of the alicyclic hydrocarbon group-containing (meth)acrylate include those exemplified above. For example, cyclohexyl acrylate and isobornyl acrylate are preferred. When an alicyclic hydrocarbon group-containing (meth)acrylate is used, its amount is not particularly limited and can be, for example, 1% by weight or more, 3% by weight or more, or 5% by weight or more of the total monomer components. In one embodiment, the amount of the alicyclic hydrocarbon group-containing (meth)acrylate used may be 10% by weight or more, or even 15% by weight or more of the total monomer components. The upper limit of the amount of the alicyclic hydrocarbon group-containing (meth)acrylate used is suitably approximately 40% by weight or less, for example, 30% by weight or less, or 25% by weight or less (e.g., 15% by weight or less, or even 10% by weight or less).

[0049] The polymerization method for forming (synthesizing) the polymer (A) from the monomer components is not particularly limited, and various conventionally known polymerization methods can be appropriately employed. For example, thermal polymerization such as solution polymerization, emulsion polymerization, and bulk polymerization (typically carried out in the presence of a thermal polymerization initiator); photopolymerization carried out by irradiation with light such as ultraviolet light (typically carried out in the presence of a photopolymerization initiator); and radiation polymerization carried out by irradiation with radiation such as β rays and γ rays can be appropriately employed. Two or more polymerization methods may be combined (for example, stepwise) to carry out the polymerization.

[0050] The solvent for solution polymerization (polymerization solvent) can be any one solvent selected from the following, or a mixed solvent of two or more solvents: aromatic compounds (typically aromatic hydrocarbons) such as toluene; esters such as ethyl acetate and butyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; halogenated alkanes such as 1,2-dichloroethane; lower alcohols (for example, monohydric alcohols having 1 to 4 carbon atoms) such as isopropyl alcohol; ethers such as tert-butyl methyl ether; and ketones such as methyl ethyl ketone.

[0051] In the polymerization, a known or commonly used thermal polymerization initiator or photopolymerization initiator can be used depending on the polymerization method, polymerization mode, etc. Such polymerization initiators can be used alone or in appropriate combination of two or more.

[0052] The thermal polymerization initiator is not particularly limited, and examples thereof include azo polymerization initiators, peroxide initiators, redox initiators formed by combining peroxides with reducing agents, and substituted ethane initiators. More specifically, examples thereof include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2-methylpropionamidine) disulfate, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis(N,N'-dimethyleneisobutylamidine), 2,2'-azobis[N-(2-carboxyethyl)-2- Examples of initiators include, but are not limited to, azo initiators such as methylpropionamidine hydrate; persulfates such as potassium persulfate and ammonium persulfate; peroxide initiators such as benzoyl peroxide, t-butyl hydroperoxide, and hydrogen peroxide; substituted ethane initiators such as phenyl-substituted ethane; and redox initiators such as a combination of a persulfate and sodium hydrogen sulfite, or a combination of a peroxide and sodium ascorbate. Thermal polymerization can be preferably carried out at a temperature of, for example, about 20 to 100°C (typically 40 to 80°C), but is not limited thereto.

[0053] The photopolymerization initiator is not particularly limited, but examples of usable photopolymerization initiators include ketal-based photopolymerization initiators, acetophenone-based photopolymerization initiators, benzoin ether-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, and thioxanthone-based photopolymerization initiators.

[0054] The amount of the polymerization initiator used is not particularly limited and may be a normal amount depending on the polymerization method, polymerization mode, etc. For example, about 0.001 to 5 parts by weight (typically about 0.01 to 2 parts by weight, for example, about 0.01 to 1 part by weight) of the polymerization initiator can be used per 100 parts by weight of the monomer to be polymerized.

[0055] In the polymerization, various conventionally known chain transfer agents (which may also be understood as molecular weight regulators or polymerization degree regulators) may be used as needed. Examples of the chain transfer agent include mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, thioglycolic acid, and α-thioglycerol. Alternatively, a chain transfer agent that does not contain a sulfur atom (non-sulfur chain transfer agent) may be used. Specific examples of non-sulfur chain transfer agents include anilines such as N,N-dimethylaniline and N,N-diethylaniline; terpenoids such as α-pinene and terpinolene; styrenes such as α-methylstyrene and α-methylstyrene dimer; compounds having a benzylidenyl group such as dibenzylideneacetone, cinnamyl alcohol, and cinnamylaldehyde; hydroquinones such as hydroquinone and naphthohydroquinone; quinones such as benzoquinone and naphthoquinone; olefins such as 2,3-dimethyl-2-butene and 1,5-cyclooctadiene; alcohols such as phenol, benzyl alcohol, and allyl alcohol; and benzyl hydrogen compounds such as diphenylbenzene and triphenylbenzene. The chain transfer agents can be used alone or in combination of two or more. The technology disclosed herein can also be preferably implemented in an embodiment that does not use a chain transfer agent.

[0056] When a chain transfer agent is used, the amount used can be, for example, about 0.005 to 1 part by weight per 100 parts by weight of the monomer components. In some embodiments, from the viewpoint of impact resistance, the amount of chain transfer agent used per 100 parts by weight of the monomer components can be, for example, 0.01 parts by weight or more, or even 0.03 parts by weight or more, or even 0.05 parts by weight or more, or even 0.07 parts by weight or more. Furthermore, in some embodiments, from the viewpoint of deformation resistance, the amount of chain transfer agent used per 100 parts by weight of the monomer components can be, for example, 0.5 parts by weight or less, or even 0.2 parts by weight or less, or even even less than 0.1 part by weight (e.g., 0.09 parts by weight or less).

[0057] In the technology disclosed herein, the glass transition temperature (Tg) of the polymer (A) is not particularly limited, but is usually suitably less than 0°C, preferably less than -10°C, and more preferably less than -20°C. A decrease in the Tg of the polymer (A) tends to improve the impact resistance. In some embodiments, the Tg of the polymer (A) may be less than -25°C or less than -30°C. The Tg of the polymer (A) is typically -80°C or higher, for example, -70°C or higher, -60°C or higher, or -55°C or higher. From the viewpoint of increasing the tensile modulus, in some embodiments, the Tg of the polymer (A) is preferably -50°C or higher, more preferably -45°C or higher, and may be -40°C or higher, -38°C or higher, or -35°C or higher.

[0058] Here, in this specification, the Tg of a polymer refers to the Tg calculated by Fox's equation based on the composition of the monomer components used in preparing the polymer. The Fox's equation is a relational expression, as shown below, between the Tg of a copolymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer. 1 / Tg=Σ(Wi / Tgi)

[0059] In the above Fox formula, Tg represents the glass transition temperature (unit: K) of the copolymer, Wi represents the weight fraction of monomer i in the copolymer (copolymerization ratio on a weight basis), and Tgi represents the glass transition temperature (unit: K) of a homopolymer of monomer i. When the target polymer for specifying Tg is a homopolymer, the Tg of the homopolymer and the Tg of the target polymer will be the same.

[0060] The glass transition temperature of the homopolymer used to calculate Tg is determined based on the value described in the publicly available literature. For example, for the following monomers, the following values ​​are used as the glass transition temperatures of the homopolymers of the monomers: n-Butyl acrylate -55℃ Isostearyl acrylate -18℃ Cyclohexyl acrylate 15℃ N-vinyl-2-pyrrolidone 54℃ 4-Hydroxybutyl acrylate -40℃

[0061] For the glass transition temperatures of homopolymers of monomers other than those listed above, the values ​​given in "Polymer Handbook" (3rd Edition, John Wiley & Sons, Inc., 1989) shall be used. If multiple values ​​are given in this document, the highest value shall be used.

[0062] The weight average molecular weight (Mw) of the polymer (A) is not particularly limited. From the viewpoint of achieving a good balance between deformation resistance and impact resistance, in some embodiments, the Mw of the polymer (A) is, for example, about 10 × 10 4 It is appropriate that the value is 20 x 10 or more. 4 Preferably greater than 30 x 10 4 Ultra is also good, 40 x 10 4 Ultra is also good, 50 x 10 4 The upper limit of Mw of the polymer (A) is usually about 500 × 10 4 In view of adhesion to an adherend and peel strength, in some embodiments, the Mw of the polymer (A) may be, for example, 150×10 or less. 4 may be less than or equal to 100 x 10 4 Less than 90 x 10 is fine. 4 Less than 75 x 10 is also acceptable. 4 or less. Here, Mw refers to a value calculated in terms of standard polystyrene obtained by gel permeation chromatography (GPC). As a GPC apparatus, for example, a model named "HLC-8320GPC" (column: TSKgelGMH-H(S), manufactured by Tosoh Corporation) may be used. The same applies to the examples described below. The above examples of Mw may be applied to the Mw of the polymer (A) in the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein, or may be applied to the Mw of the polymer (A) in the pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive layer.

[0063] (Photoreactive monomer (B)) The pressure-sensitive adhesive layer in the technology disclosed herein may contain a photoreactive monomer (B) in addition to the polymer (A) (e.g., acrylic polymer (A)) described above. The photoreactive monomer (B) may be a compound having two or more ethylenically unsaturated groups in the molecule (hereinafter also referred to as the "number of functional groups"). The upper limit of the number of functional groups in the compound used as the photoreactive monomer (B) is not particularly limited. The number of functional groups may be, for example, 50 or less, 40 or less, 30 or less, 20 or less, or 15 or less. In some embodiments, a compound having 2 to 10 ethylenically unsaturated groups may be used; a compound having 2 to 8 functional groups is preferred, and a compound having 2 to 6 functional groups is more preferred. The photoreactive monomer (B) may be used singly or in combination of two or more.

[0064] The photoreactive monomer (B) contained in the pressure-sensitive adhesive layer can form a crosslinked structure by reacting the ethylenically unsaturated groups with light (e.g., ultraviolet) irradiation or the like after application to an adherend. A pressure-sensitive adhesive sheet containing the photoreactive monomer (B) in the pressure-sensitive adhesive layer can be cured by ultraviolet irradiation or the like after application to an adherend, thereby improving the deformation resistance of the pressure-sensitive adhesive layer. This can favorably achieve both good conformability to the surface shape of the adherend when applied to the adherend and high deformation resistance after application.

[0065] Examples of the ethylenically unsaturated group include, but are not limited to, an acryloyl group, a methacryloyl group, a vinyl group, and an allyl group. The two or more ethylenically unsaturated groups contained in the photoreactive monomer (B) molecule may be the same group or two or more different groups. From the viewpoint of photoreactivity, preferred ethylenically unsaturated groups include an acryloyl group and a methacryloyl group. Among these, an acryloyl group is preferred.

[0066] The functional group equivalent of the compound used as the photoreactive monomer (B) is not particularly limited. The functional group equivalent may be, for example, about 50 to 10,000 g / mol, about 50 to 8,000 g / mol, about 50 to 5,000 g / mol, about 50 to 3,000 g / mol, or about 50 to 2,000 g / mol. In some embodiments, from the viewpoint of photocurability, a compound having a functional group equivalent of about 60 to 800 g / mol (more preferably about 80 to 600 g / mol) can be preferably used as the photoreactive monomer (B).

[0067] The functional group equivalent weight of the photoreactive monomer (B) is calculated by dividing the molecular weight [g / mol] of the photoreactive monomer (B) by the number of ethylenically unsaturated functional groups contained in the photoreactive monomer (B). The molecular weight of the photoreactive monomer (B) can be obtained, for example, by gel permeation chromatography (GPC) as a weight average molecular weight converted to standard polystyrene. Alternatively, the molecular weight [g / mol] of the photoreactive monomer (B) may be the manufacturer's nominal value or a molecular weight calculated from the molecular structure.

[0068] The molecular weight of the photoreactive monomer (B) is not particularly limited and can be selected so as to optimally exhibit the desired effect. For example, a photoreactive monomer (B) having a molecular weight of approximately 20,000 or less can be used. From the viewpoint of ease of preparation and coatability of the pressure-sensitive adhesive composition, in some embodiments, the molecular weight of the photoreactive monomer (B) may be, for example, 16,000 or less, 10,000 or less, 4,000 or less, 1,500 or less, or 1,000 or less. The molecular weight of the photoreactive monomer (B) is, for example, 100 or more, typically 120 or more. From the viewpoint of processability and handleability of the pressure-sensitive adhesive sheet, in some embodiments, the molecular weight of the photoreactive monomer (B) may be, for example, 150 or more, 200 or more, 280 or more, 350 or more, 420 or more, 480 or more, or 550 or more.

[0069] In the pressure-sensitive adhesive sheet disclosed herein, the amount of photoreactive monomer (B) contained in the pressure-sensitive adhesive layer is not particularly limited and can be appropriately set depending on the target performance (e.g., the tensile modulus of the pressure-sensitive adhesive layer after photocuring). In some embodiments in which the pressure-sensitive adhesive layer contains a polymer (A) and a photoreactive monomer (B), the amount of photoreactive monomer (B) per 100 parts by weight of the polymer (A) contained in the pressure-sensitive adhesive layer may be, for example, 1 part by weight or more, and typically 3 parts by weight or more is appropriate. From the viewpoint of facilitating an increase in the tensile modulus of the pressure-sensitive adhesive layer after photocuring, the amount of photoreactive monomer (B) per 100 parts by weight of the polymer (A) may be 5 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, or 20 parts by weight or more. Furthermore, from the viewpoint of the cohesiveness of the adhesive layer before photocuring and the handleability (e.g., processability) of the adhesive sheet, the amount of photoreactive monomer (B) per 100 parts by weight of polymer (A) is usually appropriate to be 80 parts by weight or less, preferably 60 parts by weight or less, or may be 50 parts by weight or less, 40 parts by weight or less, or 35 parts by weight or less.

[0070] In some embodiments, the pressure-sensitive adhesive layer preferably contains, as the photoreactive monomer (B), at least a compound B1 having a ring structure and two or more ethylenically unsaturated groups in the molecule. A pressure-sensitive adhesive layer containing a compound B1 with such a structure can effectively improve the deformation resistance of the pressure-sensitive adhesive layer upon light irradiation. The ring in the ring structure may be an aliphatic ring or an aromatic ring. The ring may also be a carbocyclic ring or a heterocyclic ring. The number of rings contained in one molecule of compound B1 may be one or two or more. The upper limit of the number of rings contained in compound B1 is not particularly limited, and may be, for example, 100 or less, 70 or less, 50 or less, 30 or less, 15 or less, 8 or less, 6 or less, 5 or less, or 4 or less. When compound B1 contains two or more rings, these rings may or may not form a fused ring (typically a bicyclic or tricyclic fused ring) with one or more rings. The ring is preferably included in the main chain of compound B1. That is, it is preferable that one ethylenically unsaturated group in compound B1 and at least one other ethylenically unsaturated group are linked via the ring structure. Compound B1 can be used alone or in combination of two or more.

[0071] Compound B1 preferably has a ring structure and two or more ethylenically unsaturated groups in the molecule and a functional group equivalent of 100 g / mol or more. A pressure-sensitive adhesive sheet containing compound B1 satisfying the above-mentioned functional group equivalent in its adhesive layer can favorably form a bond with high deformation resistance and high impact resistance. The reason for this effect is not particularly limited, but it is believed that compound B1 effectively increases the tensile modulus of the adhesive layer after light irradiation due to the rigidity of the ring structure, thereby imparting deformation resistance, while the functional group equivalent of compound B1, which is a predetermined value or more, maintains the distance between crosslinking points, thereby forming a crosslinked structure with high impact resistance. In some embodiments, the functional group equivalent of compound B1 may be, for example, 120 g / mol or more, 150 g / mol or more, 180 g / mol or more, 230 g / mol or more, 280 g / mol or more, 320 g / mol or more, or 350 g / mol or more. The impact resistance tends to improve with an increase in the functional group equivalent weight of compound B1. The functional group equivalent weight of compound B1 may be, for example, 10,000 g / mol or less, 8,000 g / mol or less, 5,000 g / mol or less, 3,000 g / mol or less, or 2,000 g / mol or less. In some embodiments, from the viewpoint of photocurability, etc., the functional group equivalent weight of compound B1 is preferably 800 g / mol or less, more preferably 600 g / mol or less. In some embodiments, the functional group equivalent weight of compound B1 may be 500 g / mol or less, 400 g / mol or less, or 300 g / mol or less.

[0072] In some embodiments, the number of functional groups of compound B1 (i.e., the number of ethylenically unsaturated groups contained in the molecule) may be, for example, 2 to 50, 2 to 40, 2 to 30, or 2 to 10, and preferably, for example, 2 to 6, or 2 to 4, or 2 to 3. In some embodiments, compound B1 having 2 functional groups may be preferably used.

[0073] Compound B1 may have a functional group other than an ethylenically unsaturated group. Examples of the functional group other than an ethylenically unsaturated group include a hydroxyl group, a carboxyl group, and an amino group. Preferred examples of the functional group other than an ethylenically unsaturated group include a hydroxyl group and an amino group.

[0074] Examples of compound B1 include bisphenol A-type epoxy (meth)acrylates such as bisphenol A glycidyl ether (meth)acrylic acid adduct, bisphenol A glycidylamine (meth)acrylic acid adduct, and bisphenol A glycidyl ester (meth)acrylic acid adduct; alkylene oxide-modified bisphenol A (meth)acrylates such as ethylene oxide (EO)-modified bisphenol A di(meth)acrylate and propylene oxide (PO)-modified bisphenol A di(meth)acrylate; bisphenol F-type epoxy (meth)acrylates such as bisphenol F glycidyl ether (meth)acrylic acid adduct, bisphenol F glycidylamine (meth)acrylic acid adduct, and bisphenol F glycidyl ester (meth)acrylic acid adduct; alkylene oxide-modified bisphenol F (meth)acrylates such as EO-modified bisphenol F di(meth)acrylate and PO-modified bisphenol F di(meth)acrylate; bisphenol E glycidyl ether (meth)acrylic acid adduct, bisphenol E Bisphenol E type epoxy (meth)acrylates such as glycidylamine (meth)acrylic acid adduct and bisphenol E glycidyl ester (meth)acrylic acid adduct; alkylene oxide modified bisphenol E (meth)acrylates such as EO modified bisphenol E di(meth)acrylate and PO modified bisphenol E di(meth)acrylate; 9,9-bis(4-hydroxyphenyl)fluorene di(meth)acrylate, 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene di(meth)acrylate (meth)acrylates containing a fluorene skeleton, such as acrylate; and aliphatic rings (alicyclic fused rings) such as tricyclodecane dimethanol di(meth)acrylate, hydrogenated bisphenol A type epoxy (meth)acrylate, hydrogenated bisphenol F type epoxy (meth)acrylate, hydrogenated bisphenol E type epoxy (meth)acrylate, hydrogenated phthalic acid type epoxy (meth)acrylate, hydrogenated terpene phenol (meth)acrylate, and 1,4-cyclohexane dimethanol diglycidyl ether (meth)acrylate.(meth)acrylates having the following structure; (meth)acrylic acid adducts of novolac-type epoxy resins; (meth)acrylic acid adducts of thioether-type epoxy resins; (meth)acrylic acid adducts of naphthalene-type epoxy resins; (meth)acrylic acid adducts of dicyclopentadiene-type epoxy resins; (meth)acrylic acid adducts of alkyldiphenol-type epoxy resins; (meth)acrylic acid adducts of biphenyl-type epoxy resins; (meth)acrylic acid adducts of terpene phenol resins; isocyanurate-type (meth)acrylates such as tris(2-hydroxyethyl)isocyanurate di(meth)acrylate and tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate; divinylbenzene; hydroquinone di(meth)acrylate; resorcinol di(meth)acrylate; modified products of any of the above materials (e.g., amine-modified products, acid-modified products, halogen-modified products); and the like, but are not limited thereto. In some embodiments, a compound B1 having an aromatic carbon ring may be preferably used. Suitable examples of compound B1 include compounds containing a bisphenol A structure, such as bisphenol A type epoxy (meth)acrylate, alkylene oxide modified bisphenol A (meth)acrylate, and modified products thereof (for example, amine modified products).

[0075] Examples of commercially available products that can be used as compound B1 include, but are not limited to, products manufactured by Shin-Nakamura Chemical Co., Ltd. under the trade names "A-DCP" and "A-BPE-4," products manufactured by Osaka Organic Chemical Industry Co., Ltd. under the trade names "Viscoat #540" and "Viscoat #700HV," products manufactured by Nippon Kayaku Co., Ltd. under the trade names "Epoxy Ester 3000A" and "Epoxy Ester 80MFA" manufactured by Kyoeisha Chemical Co., Ltd., and products manufactured by Daicel Allnex under the trade names "EBECRYL 3700," "EBECRYL 3703," and "EBECRYL 3603."

[0076] The amount of compound B1 relative to 100 parts by weight of polymer (A) contained in the pressure-sensitive adhesive layer is not particularly limited and can be, for example, 0.5 parts by weight or more. From the viewpoint of easily obtaining a pressure-sensitive adhesive layer that achieves a good balance between deformation resistance and impact resistance, in some embodiments, the amount of compound B1 relative to 100 parts by weight of polymer (A) may be, for example, 1 part by weight or more, 3 parts by weight or more, 5 parts by weight or more, 7 parts by weight or more, 10 parts by weight or more, or 15 parts by weight or more. Furthermore, from the viewpoint of the cohesiveness of the pressure-sensitive adhesive layer before photocuring and the handleability of the pressure-sensitive adhesive sheet, the amount of compound B1 relative to 100 parts by weight of polymer (A) is usually suitably 80 parts by weight or less, preferably 60 parts by weight or less, and may be 50 parts by weight or less, 40 parts by weight or less, or 35 parts by weight or less.

[0077] In some embodiments, the pressure-sensitive adhesive layer may contain, as the photoreactive monomer (B), a compound B2 having two or more functional groups and no ring structure in the molecule. Compound B2 is preferably used in combination with compound B1. This adjusts the crosslinked structure of the pressure-sensitive adhesive layer, allowing for the formation of a bond that more suitably balances deformation resistance and impact resistance. Compound B2 may be used alone or in combination of two or more.

[0078] The number of functional groups of compound B2 may be, for example, 50 or less, 40 or less, 30 or less, 20 or less, or 15 or less. The number of functional groups of compound B2 used in some embodiments may be, for example, 2 to 10, preferably 3 to 10, or may be 3 to 8, or may be 4 to 6. For example, in an embodiment in which a compound having two functional groups is used as compound B1, it may be advantageous to use compound B2 having three or more functional groups (preferably four or more, more preferably five or more, and even more preferably six or more).

[0079] The functional group equivalent weight of compound B2 is not particularly limited and may be, for example, 5000 g / mol or less, 2000 g / mol or less, or 1000 g / mol or less. In some embodiments, the functional group equivalent weight of compound B2 may be, for example, 600 g / mol or less, and from the viewpoint of improving photocurability and hardness of the cured product, may be 400 g / mol or less, 300 g / mol or less, 200 g / mol or less, 150 g / mol or less, or 100 g / mol or less. The functional group equivalent weight of compound B2 is typically 50 g / mol or more, preferably 60 g / mol or more, 70 g / mol or more, 80 g / mol or more, or 90 g / mol or more.

[0080] Examples of compounds that can be used as compound B2 include, but are not limited to, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, trimethylolethane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, neopentyl glycol di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, EO-modified or PO-modified products of any of the above-mentioned materials, and the like.

[0081] In embodiments using compound B2, the amount of compound B2 relative to 100 parts by weight of polymer (A) contained in the pressure-sensitive adhesive layer is not particularly limited and can be, for example, 0.1 parts by weight or more. From the viewpoint of easily obtaining a pressure-sensitive adhesive layer that achieves a good balance between deformation resistance and impact resistance, in some embodiments, the amount of compound B2 relative to 100 parts by weight of polymer (A) may be, for example, 1 part by weight or more, 2 parts by weight or more, 4 parts by weight or more, 6 parts by weight or more, 10 parts by weight or more, or 12 parts by weight or more. Furthermore, from the viewpoint of suppressing a decrease in adhesion to the adherend due to excessive crosslinking, in some embodiments, the amount of compound B2 relative to 100 parts by weight of polymer (A) is, for example, suitably 25 parts by weight or less, preferably 17 parts by weight or less, or may be 15 parts by weight or less, 13 parts by weight or less, or may be 9 parts by weight or less.

[0082] In embodiments in which compounds B1 and B2 are used in combination, compound B2 may preferably be a compound having three or more functional groups and a functional group equivalent weight smaller than that of compound B1 used in combination therewith. In some embodiments, the ratio of the functional group equivalent weight FE2 of compound B2 to the functional group equivalent weight FE1 of compound B1 (FE2 / FE1) may be, for example, 0.9 or less, 0.7 or less, 0.5 or less, or 0.4 or less. In such embodiments, the effect of improving the tensile modulus of elasticity due to the photoreactive monomer (B) can be efficiently exerted. The lower limit of the ratio (FE2 / FE1) is not particularly limited and may be, for example, 0.01 or more, 0.1 or more, or 0.2 or more.

[0083] In embodiments in which Compound B1 and Compound B2 are used in combination, the weight ratio (W2 / W1) of the amount W2 of Compound B2 to the amount W1 of Compound B1 is not particularly limited. In some embodiments, the weight ratio (W2 / W1) may be, for example, 0.05 to 10, 0.1 to 5, 0.2 to 3, or 0.3 to 2. By setting the weight ratio (W2 / W1) to any of the above ranges, the effects of using Compound B1 and Compound B2 in combination tend to be more favorably exhibited.

[0084] In some embodiments of the pressure-sensitive adhesive sheet disclosed herein, the photoreactive monomer (B) may be contained in the pressure-sensitive adhesive layer in a free form. Such a pressure-sensitive adhesive layer can be suitably formed using a pressure-sensitive adhesive composition containing the photoreactive monomer (B) in a free form. Here, "free form" means that the photoreactive monomer (B) is not chemically bonded to other components (e.g., polymer (A)) contained in the pressure-sensitive adhesive layer or the pressure-sensitive adhesive composition. A pressure-sensitive adhesive composition containing the photoreactive monomer (B) in a free form may be advantageous in terms of ease of preparation and suppression of gelation.

[0085] In some other embodiments of the pressure-sensitive adhesive sheet disclosed herein, at least a portion of the photoreactive monomer (B) may be contained in the pressure-sensitive adhesive layer in a form chemically bonded to other components (e.g., polymer (A), a crosslinking agent described below, etc.) contained in the pressure-sensitive adhesive layer or the pressure-sensitive adhesive composition, from the viewpoint of improving the processability of the pressure-sensitive adhesive sheet. The chemical bond may be, for example, a bond formed by reaction between a functional group F1 other than an ethylenically unsaturated group contained in the molecule of the photoreactive monomer (B) and a functional group F2 contained in the molecule of the other component and capable of reacting with the functional group F1. The other component may be a crosslinking agent, and the photoreactive monomer (B) may be bonded to the polymer (A) via the crosslinking agent.

[0086] (acrylic oligomer) The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein may contain an acrylic oligomer from the viewpoint of improving cohesive strength and improving adhesion to a surface adjacent to the pressure-sensitive adhesive layer (for example, the surface of a support in a pressure-sensitive adhesive sheet, the surface of an adherend to which the pressure-sensitive adhesive sheet is attached, etc.). The pressure-sensitive adhesive layer containing an acrylic oligomer can be preferably formed using a pressure-sensitive adhesive composition containing the acrylic oligomer. As the acrylic oligomer, one having a higher Tg than the Tg of the above-mentioned polymer (A) can be preferably used.

[0087] The Tg of the acrylic oligomer is not particularly limited and may be, for example, about 20°C or higher and 300°C or lower. The Tg may be, for example, about 30°C or higher, about 40°C or higher, about 60°C or higher, about 80°C or higher, or about 100°C or higher. As the Tg of the acrylic oligomer increases, the effect of improving cohesive strength generally tends to increase. Furthermore, from the viewpoints of anchoring to the support and impact absorption, the Tg of the acrylic oligomer may be, for example, about 250°C or lower, about 200°C or lower, about 180°C or lower, or about 150°C or lower. The Tg of the acrylic oligomer, like the Tg of polymer (A), is a value calculated based on the Fox formula.

[0088] The Mw of the acrylic oligomer is not particularly limited and may be, for example, approximately 1,000 or more, typically approximately 1,500 or more, approximately 2,000 or more, or approximately 3,000 or more. The Mw of the acrylic oligomer may be, for example, less than approximately 30,000, typically approximately less than 10,000, or approximately less than 7,000 or approximately less than 5,000. When the Mw is within the above range, the effect of improving the cohesiveness of the pressure-sensitive adhesive layer and the adhesion to adjacent surfaces is easily achieved. The Mw of the acrylic oligomer can be measured by gel permeation chromatography (GPC) and calculated as a value equivalent to standard polystyrene. Specifically, for example, it can be measured using a Tosoh HPLC 8020 with two TSKgel GMH-H (20) columns at a flow rate of approximately 0.5 mL / min in tetrahydrofuran solvent.

[0089] Examples of the monomer components constituting the acrylic oligomer include the above-mentioned various (meth)acrylic acids C 1-20 Examples of (meth)acrylate monomers include alkyl esters, the various alicyclic hydrocarbon group-containing (meth)acrylates described above, the various aromatic hydrocarbon group-containing (meth)acrylates described above, and (meth)acrylates obtained from alcohols derived from terpene compounds. These can be used alone or in combination of two or more.

[0090] From the viewpoint of improving adhesiveness, it is preferable that the acrylic oligomer contains, as a monomer unit, an acrylic monomer having a relatively bulky structure, such as an alkyl (meth)acrylate in which the alkyl group has a branched structure, such as isobutyl (meth)acrylate or t-butyl (meth)acrylate; an alicyclic hydrocarbon group-containing (meth)acrylate; or an aromatic hydrocarbon group-containing (meth)acrylate. Furthermore, when ultraviolet light is used in synthesizing the acrylic oligomer or producing the pressure-sensitive adhesive layer, a monomer having a saturated hydrocarbon group at the ester end is preferred because it is less likely to cause polymerization inhibition. For example, an alkyl (meth)acrylate in which the alkyl group has a branched structure or a saturated alicyclic hydrocarbon group-containing (meth)acrylate can be suitably used.

[0091] The proportion of (meth)acrylate monomers in all monomer components constituting the acrylic oligomer is typically more than 50% by weight, preferably 60% by weight or more, more preferably 70% by weight or more (e.g., 80% by weight or more, or even 90% by weight or more). In a preferred embodiment, the acrylic oligomer has a monomer composition consisting essentially of one or more (meth)acrylate monomers. For example, the monomer components constituting the acrylic oligomer are an alicyclic hydrocarbon group-containing (meth)acrylate and (meth)acrylic acid C. 1-20 When the alicyclic hydrocarbon group-containing (meth)acrylate / (meth)acrylic acid C is contained, the weight ratio thereof is not particularly limited. 1-20 The weight ratio of the alkyl esters can be, for example, 10 / 90 or more, 20 / 80 or more, or 30 / 70 or more, and can be 90 / 10 or less, 80 / 20 or less, or 70 / 30 or less.

[0092] In addition to the (meth)acrylate monomers described above, functional group-containing monomers can be used as necessary as constituent monomer components of the acrylic oligomer. Examples of functional group-containing monomers include nitrogen-containing heterocyclic monomers such as N-vinyl-2-pyrrolidone and N-acryloylmorpholine; amino group-containing monomers such as N,N-dimethylaminoethyl (meth)acrylate; amide group-containing monomers such as N,N-diethyl (meth)acrylamide; carboxy group-containing monomers such as acrylic acid (AA) and methacrylic acid (MAA); and hydroxy group-containing monomers such as 2-hydroxyethyl (meth)acrylate. These functional group-containing monomers can be used alone or in combination of two or more. When a functional group-containing monomer is used, the proportion of the functional group-containing monomer in the total monomer components constituting the acrylic oligomer can be, for example, 1% by weight or more, 2% by weight or more, or 3% by weight or more, and can be, for example, 15% by weight or less, 10% by weight or less, or 7% by weight or less. The acrylic oligomer may not contain a functional group-containing monomer.

[0093] Suitable acrylic oligomers include, for example, homopolymers of dicyclopentanyl methacrylate (DCPMA), cyclohexyl methacrylate (CHMA), isobornyl methacrylate (IBXMA), isobornyl acrylate (IBXA), dicyclopentanyl acrylate (DCPA), 1-adamantyl methacrylate (ADMA), and 1-adamantyl acrylate (ADA), as well as copolymers of DCPMA and MMA, copolymers of DCPMA and IBXMA, copolymers of ADA and methyl methacrylate (MMA), copolymers of CHMA and isobutyl methacrylate (IBMA), copolymers of CHMA and IBXMA, copolymers of CHMA and acryloylmorpholine (ACMO), copolymers of CHMA and diethylacrylamide (DEAA), and copolymers of CHMA and AA.

[0094] The acrylic oligomer can be formed by polymerizing its constituent monomer components. The polymerization method and polymerization mode are not particularly limited, and various conventionally known polymerization methods (e.g., solution polymerization, emulsion polymerization, bulk polymerization, photopolymerization, radiation polymerization, etc.) can be used in an appropriate mode. The types of polymerization initiators (e.g., azo-based polymerization initiators) that can be used as needed are generally as exemplified for the synthesis of the acrylic polymer (A). The amount of polymerization initiator and the amount of an optionally used chain transfer agent (e.g., mercaptans) are appropriately set based on common technical knowledge so as to achieve the desired molecular weight, and therefore detailed explanations are omitted.

[0095] When an acrylic oligomer is contained in the pressure-sensitive adhesive layer or pressure-sensitive adhesive composition, the content thereof can be, for example, 0.01 parts by weight or more relative to 100 parts by weight of polymer (A). From the viewpoint of obtaining a higher effect, it may be 0.05 parts by weight or more, or 0.1 parts by weight or more, or 0.2 parts by weight or more. Furthermore, from the viewpoint of compatibility with polymer (A), the content of the acrylic oligomer relative to 100 parts by weight of polymer (A) is usually appropriate to be less than 50 parts by weight, preferably less than 30 parts by weight, and more preferably 25 parts by weight or less, for example, 10 parts by weight or less, 5 parts by weight or less, or 1 part by weight or less. The pressure-sensitive adhesive layer or pressure-sensitive adhesive composition may be free of an acrylic oligomer.

[0096] The PSA layer or PSA composition of the PSA sheet disclosed herein may optionally contain various additives common in the field of PSA, such as tackifying resins (e.g., rosin-based, petroleum-based, terpene-based, phenol-based, ketone-based, etc. tackifying resins), viscosity modifiers (e.g., thickeners), leveling agents, plasticizers, fillers, colorants such as pigments and dyes, stabilizers, preservatives, antioxidants, etc. These various additives can be conventionally known and can be used in the usual way, and are not particularly characteristic of the present invention, so detailed description thereof will be omitted. The technology disclosed herein can exhibit good adhesive strength without using the above-mentioned tackifier resin. Therefore, in some embodiments, the content of the tackifier resin in the PSA layer or PSA composition can be, for example, less than 10 parts by weight, or even less than 5 parts by weight, per 100 parts by weight of polymer (A). The content of the tackifier resin may be less than 1 part by weight (e.g., less than 0.5 parts by weight), or may be less than 0.1 parts by weight (0 parts by weight or more but less than 0.1 parts by weight). The PSA layer or PSA composition may not contain a tackifier resin.

[0097] When the pressure-sensitive adhesive sheet disclosed herein is used for optical applications, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet may have predetermined optical properties (e.g., transparency). From the viewpoint of such optical properties, it is preferable that the amount of components other than the polymer (A) and the photoreactive monomer (B), which is used as needed, in the pressure-sensitive adhesive layer (and thus the pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive layer) is limited. In the technology disclosed herein, the amount of components other than the polymer (A) and the photoreactive monomer (B) in the pressure-sensitive adhesive layer is usually about 30% by weight or less, suitably about 15% by weight or less, and preferably about 12% by weight or less (e.g., about 10% by weight or less). In the pressure-sensitive adhesive sheet according to one embodiment, the amount of components other than the polymer (A) and the photoreactive monomer (B) in the pressure-sensitive adhesive layer may be about 5% by weight or less, about 3% by weight or less, or about 1.5% by weight or less (e.g., about 1% by weight or less).

[0098] (Crosslinking agent) A crosslinking agent may be used in the pressure-sensitive adhesive layer as needed. In the pressure-sensitive adhesive sheet disclosed herein, the crosslinking agent is typically contained in the pressure-sensitive adhesive layer in a form after a crosslinking reaction. The use of a crosslinking agent makes it possible to appropriately adjust the cohesive strength, etc., of the pressure-sensitive adhesive layer. Furthermore, in a pressure-sensitive adhesive sheet containing a photoreactive monomer (B) in the pressure-sensitive adhesive layer, the use of a crosslinking agent in combination with the photoreactive monomer (B) makes it possible to favorably achieve both the flexibility of the pressure-sensitive adhesive layer before photocuring of the photoreactive monomer and the deformation resistance of the pressure-sensitive adhesive layer after photocuring.

[0099] The type of crosslinking agent is not particularly limited, and can be selected from conventionally known crosslinking agents so that the crosslinking agent exerts an appropriate crosslinking function within the pressure-sensitive adhesive layer, for example, depending on the composition of the pressure-sensitive adhesive composition. Examples of crosslinking agents that can be used include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, carbodiimide-based crosslinking agents, melamine-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, hydrazine-based crosslinking agents, and amine-based crosslinking agents. These can be used alone or in combination of two or more.

[0100] The isocyanate crosslinking agent may be a bifunctional or higher polyfunctional isocyanate compound, such as aromatic isocyanates such as tolylene diisocyanate, xylene diisocyanate, polymethylene polyphenyl diisocyanate, tris(p-isocyanatophenyl)thiophosphate, and diphenylmethane diisocyanate; alicyclic isocyanates such as isophorone diisocyanate; and aliphatic isocyanates such as hexamethylene diisocyanate. Examples of commercially available products include isocyanate adducts such as trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate L"), trimethylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate HL"), hexamethylene diisocyanate isocyanurate (manufactured by Tosoh Corporation, trade name "Coronate HX"), and trimethylolpropane / xylylene diisocyanate adduct (manufactured by Mitsui Chemicals, Inc., trade name "Takenate D-110N").

[0101] As the epoxy-based crosslinking agent, those having two or more epoxy groups per molecule can be used without particular limitation. Epoxy-based crosslinking agents having 3 to 5 epoxy groups per molecule are preferred. Specific examples of epoxy-based crosslinking agents include N,N,N',N'-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, polyglycerol polyglycidyl ether, etc. Commercially available epoxy-based crosslinking agents include "TETRAD-X" and "TETRAD-C" manufactured by Mitsubishi Gas Chemical Company, Inc., "Epicron CR-5L" manufactured by DIC Corporation, "Denacol EX-512" manufactured by Nagase ChemteX Corporation, and "TEPIC-G" manufactured by Nissan Chemical Industries, Ltd.

[0102] As the oxazoline-based crosslinking agent, any agent having one or more oxazoline groups in one molecule can be used without any particular limitation. Examples of the aziridine crosslinking agent include trimethylolpropane tris[3-(1-aziridinyl)propionate], trimethylolpropane tris[3-(1-(2-methyl)aziridinylpropionate)], and the like. As the carbodiimide crosslinking agent, a low molecular weight compound or a high molecular weight compound having two or more carbodiimide groups can be used.

[0103] In some embodiments, peroxides may be used as crosslinking agents. Examples of peroxides include di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxyisobutyrate, and dibenzoyl peroxide. Among these, peroxides that exhibit particularly excellent crosslinking reaction efficiency include di(4-t-butylcyclohexyl)peroxydicarbonate, dilauroyl peroxide, and dibenzoyl peroxide. When peroxides are used as the polymerization initiator, the remaining peroxides that are not used in the polymerization reaction can also be used in the crosslinking reaction. In this case, the remaining amount of peroxide should be quantified, and if the proportion of peroxide is less than the predetermined amount, peroxide should be added as necessary to reach the predetermined amount. The quantification of peroxide can be carried out by the method described in Japanese Patent No. 4971517.

[0104] When a crosslinking agent is used, the amount used (when two or more crosslinking agents are used, the total amount) is not particularly limited. From the viewpoint of realizing a pressure-sensitive adhesive that exhibits well-balanced adhesive properties such as adhesive strength and cohesive strength, the amount of crosslinking agent used is usually approximately 5 parts by weight or less per 100 parts by weight of polymer (A), and may be 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, or even less than 1 part by weight. In an embodiment in which a crosslinking agent and a photoreactive monomer (B) are used in combination, from the viewpoint of favorably exhibiting the effects of such combined use, the amount of crosslinking agent used per 100 parts by weight of polymer (A) may be, for example, 0.80 parts by weight or less, 0.60 parts by weight or less, 0.30 parts by weight or less, or 0.10 parts by weight or less. There is no particular lower limit on the amount of crosslinking agent used, and it may be used in an amount greater than 0 parts by weight per 100 parts by weight of polymer (A). In some embodiments, the amount of the crosslinking agent used can be, for example, 0.001 parts by weight or more, or may be 0.01 parts by weight or more, or may be 0.03 parts by weight or more, relative to 100 parts by weight of the polymer (A).

[0105] The technology disclosed herein can be preferably implemented in an embodiment using at least an isocyanate-based crosslinking agent as a crosslinking agent. The isocyanate-based crosslinking agent may be used in combination with other crosslinking agents. In an embodiment using an isocyanate-based crosslinking agent, the amount of the isocyanate-based crosslinking agent used relative to 100 parts by weight of polymer (A) may be, for example, 0.005 parts by weight or more, 0.01 parts by weight or more, or 0.03 parts by weight or more. Furthermore, the amount of the isocyanate-based crosslinking agent used relative to 100 parts by weight of polymer (A) may be, for example, 10 parts by weight or less, 5 parts by weight or less, 3 parts by weight or less, less than 2 parts by weight, less than 1 part by weight, less than 0.80 parts by weight, less than 0.60 parts by weight, less than 0.30 parts by weight, less than 0.10 parts by weight, or less than 0.08 parts by weight.

[0106] A crosslinking catalyst may be used to promote the crosslinking reaction more effectively. Examples of crosslinking catalysts include metal-based crosslinking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, nursem ferric, butyltin oxide, and dioctyltin dilaurate. Among these, tin-based crosslinking catalysts such as dioctyltin dilaurate are preferred. The amount of the crosslinking catalyst used is not particularly limited. The amount of the crosslinking catalyst used may be, for example, approximately 0.0001 parts by weight or more, approximately 0.001 parts by weight or more, or approximately 0.005 parts by weight or more, relative to 100 parts by weight of the polymer (A), and may be approximately 1 part by weight or less, approximately 0.1 parts by weight or less, or approximately 0.05 parts by weight or less.

[0107] The PSA composition used to form the PSA layer may optionally contain a compound that undergoes keto-enol tautomerization as a crosslinking retarder. For example, a compound that undergoes keto-enol tautomerization may be preferably used in a PSA composition containing an isocyanate-based crosslinking agent or a PSA composition that can be used by blending an isocyanate-based crosslinking agent. This can provide the effect of extending the pot life of the PSA composition. Various β-dicarbonyl compounds can be used as compounds that undergo keto-enol tautomerization. Specific examples include β-diketones such as acetylacetone and 2,4-hexanedione; acetoacetate esters such as methyl acetoacetate and ethyl acetoacetate; propionylacetate esters such as ethyl propionylacetate; isobutyrylacetate esters such as ethyl isobutyrylacetate; and malonate esters such as methyl malonate and ethyl malonate. Among these, acetylacetone and acetoacetate esters are particularly preferred. The compounds that undergo keto-enol tautomerization can be used alone or in combination of two or more. The amount of the compound that undergoes keto-enol tautomerization used may be, for example, 0.1 parts by weight or more and 20 parts by weight or less, and usually 0.5 parts by weight or more and 15 parts by weight or less, per 100 parts by weight of polymer (A), and can be, for example, 1 part by weight or more and 10 parts by weight or less, or may be 1 part by weight or more and 5 parts by weight or less.

[0108] (Silane coupling agent) The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein may optionally contain a silane coupling agent. The use of a silane coupling agent can improve the peel strength of the pressure-sensitive adhesive sheet from an adherend (e.g., a glass plate). A pressure-sensitive adhesive layer containing a silane coupling agent can be suitably formed using a pressure-sensitive adhesive composition containing a silane coupling agent. In such a pressure-sensitive adhesive composition, the silane coupling agent is preferably contained in the pressure-sensitive adhesive composition in a free form, from the viewpoint of inhibiting gelation, etc. In some embodiments, the silane coupling agent is preferably contained in a free form in the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein. The silane coupling agent contained in the pressure-sensitive adhesive layer in such a form can effectively contribute to improving the peel strength. Here, "free form" means that the silane coupling agent is not chemically bonded to other components contained in the pressure-sensitive adhesive composition or the pressure-sensitive adhesive layer.

[0109] Examples of silane coupling agents include silicon compounds having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)3-aminopropyltrimethoxysilane, N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane; 3-chloropropyltrimethoxysilane; acetoacetyl group-containing trimethoxysilane; (meth)acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane; isocyanate group-containing silane coupling agents such as 3-isocyanatepropyltriethoxysilane; etc. In some embodiments, by using a silane coupling agent having a trialkoxysilyl group, the above-mentioned effects can be more preferably exhibited. Among these, preferred silane coupling agents include 3-glycidoxypropyltrimethoxysilane and acetoacetyl group-containing trimethoxysilane.

[0110] When using a silane coupling agent, the amount used can be set so as to obtain the desired effect, and is not particularly limited. In some embodiments, the amount of silane coupling agent used may be, for example, 0.001 parts by weight or more relative to 100 parts by weight of polymer (A). From the viewpoint of obtaining a higher effect, it may be 0.01 parts by weight or more, 0.05 parts by weight or more, or even 0.1 parts by weight or more. Furthermore, from the viewpoint of suppressing gelation of the pressure-sensitive adhesive composition, the amount of silane coupling agent used relative to 100 parts by weight of polymer (A) is usually suitably 3 parts by weight or less, may be 1 part by weight or less, or may be 0.5 parts by weight or less.

[0111] (Photopolymerization initiator) The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein can contain a photopolymerization initiator as needed to improve or impart photocurability. As with the photopolymerization initiators exemplified as those usable in the synthesis of polymer (A), examples of usable photopolymerization initiators include ketal-based photopolymerization initiators, acetophenone-based photopolymerization initiators, benzoin ether-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, and thioxanthone-based photopolymerization initiators. The photopolymerization initiators can be used alone or in appropriate combinations of two or more.

[0112] Specific examples of ketal-based photopolymerization initiators include 2,2-dimethoxy-1,2-diphenylethan-1-one. Specific examples of acetophenone-based photopolymerization initiators include 1-hydroxycyclohexyl-phenyl-ketone, 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, and methoxyacetophenone. Specific examples of the benzoin ether-based photopolymerization initiator include benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, and benzoin isobutyl ether, and substituted benzoin ethers such as anisole methyl ether. Specific examples of the acylphosphine oxide photopolymerization initiator include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and the like. Specific examples of α-ketol-based photopolymerization initiators include 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one, etc. Specific examples of aromatic sulfonyl chloride-based photopolymerization initiators include 2-naphthalenesulfonyl chloride, etc. Specific examples of photoactive oxime-based photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime, etc. Specific examples of benzoin-based photopolymerization initiators include benzoin, etc. Specific examples of benzyl-based photopolymerization initiators include benzyl, etc. Specific examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexylphenyl ketone, and the like. Specific examples of the thioxanthone-based photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone.

[0113] The content of the photopolymerization initiator in the pressure-sensitive adhesive layer is not particularly limited and can be set so as to appropriately achieve the desired effect. In some embodiments, the content of the photopolymerization initiator can be, for example, approximately 0.005 parts by weight or more, typically 0.01 parts by weight or more, preferably 0.05 parts by weight or more, and may be 0.10 parts by weight or more, 0.15 parts by weight or more, or even 0.20 parts by weight or more, relative to 100 parts by weight of the polymer (A) contained in the pressure-sensitive adhesive layer. Increasing the content of the photopolymerization initiator tends to improve the photocurability of the pressure-sensitive adhesive layer. Furthermore, the content of the photopolymerization initiator relative to 100 parts by weight of the polymer (A) is typically 10 parts by weight or less, preferably 7 parts by weight or less, may be 5 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, or 1 part by weight or less. Not having an excessively high content of the photopolymerization initiator can be advantageous from the viewpoint of improving the storage stability (e.g., stability against photodegradation) of the pressure-sensitive adhesive sheet.

[0114] A pressure-sensitive adhesive layer containing a photopolymerization initiator can typically be formed using a pressure-sensitive adhesive composition (e.g., a solvent-based pressure-sensitive adhesive composition) containing the photopolymerization initiator. A pressure-sensitive adhesive composition containing a photopolymerization initiator can be prepared, for example, by mixing the photopolymerization initiator with other components used in the composition. When a pressure-sensitive adhesive composition is prepared using a polymer (A) (e.g., an acrylic polymer (A)) synthesized (photopolymerized) in the presence of a photopolymerization initiator, the residue (unreacted material) of the photopolymerization initiator used in synthesizing the polymer (A) may be used as part or all of the photopolymerization initiator contained in the pressure-sensitive adhesive layer. The same applies when an acrylic oligomer synthesized in the presence of a photopolymerization initiator is used as an optional acrylic oligomer. From the viewpoint of ease of production control, the pressure-sensitive adhesive layer disclosed herein can be preferably formed using a pressure-sensitive adhesive composition prepared by newly adding the above-mentioned amount of photopolymerization initiator to the other components.

[0115] In addition, the pressure-sensitive adhesive layer in the technology disclosed herein may contain, as needed, known additives that can be used in pressure-sensitive adhesives, such as leveling agents, plasticizers, softeners, colorants (dyes, pigments, etc.), fillers, antistatic agents, antioxidants, UV absorbers, antioxidants, light stabilizers, preservatives, etc. In pressure-sensitive adhesive sheets intended for applications that do not favor the inclusion of siloxane (e.g., applications in the manufacture of electronic devices), it is desirable to avoid the use of silicone-based additives (e.g., silicone-based leveling agents and antifoaming agents).

[0116] <Formation of adhesive layer> The pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet disclosed herein may be a cured layer of a pressure-sensitive adhesive composition containing the corresponding component. That is, the pressure-sensitive adhesive layer may be formed by applying (e.g., coating) the pressure-sensitive adhesive composition to a suitable surface, followed by appropriate curing treatments such as drying (e.g., heat drying), crosslinking (e.g., crosslinking by the reaction of the above-mentioned crosslinking agent), and cooling. When two or more curing treatments are performed, they may be performed simultaneously or stepwise.

[0117] In some embodiments, the pressure-sensitive adhesive composition contains at least any one of the polymers (A) described above. A preferred embodiment of the pressure-sensitive adhesive composition contains an acrylic polymer (A) as the polymer (A). The pressure-sensitive adhesive composition may contain the polymer (A) in the form of a precursor thereof. The pressure-sensitive adhesive composition preferably contains any one of the polymers (A) described above and any one of the photoreactive monomers (B) described above. The photoreactive monomer (B) preferably contains a compound B1 having a ring structure and two or more ethylenically unsaturated groups in the molecule. The compound B1 preferably has a molecular weight per ethylenically unsaturated group of 100 g / mol or more.

[0118] The form of the PSA composition is not particularly limited, and may be any of various conventionally known forms, such as a water-dispersed PSA composition in which a PSA (adhesive component) is dispersed in water, a solvent-based PSA composition in which a PSA is contained in an organic solvent, or a hot-melt PSA composition that is applied in a heated and molten state and forms a PSA upon cooling to around room temperature. In some embodiments, solvent-based PSA compositions are preferably used from the viewpoints of ease of preparation of the PSA composition and ease of formation of the PSA layer. Solvent-based PSA compositions are preferably prepared using a polymer (A) that is a polymer obtained by solution polymerization of monomer components.

[0119] The pressure-sensitive adhesive composition can be applied using a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, etc. In a pressure-sensitive adhesive sheet having a support, the method of providing a pressure-sensitive adhesive layer on the support may be a direct method in which the pressure-sensitive adhesive composition is directly applied to the support to form a pressure-sensitive adhesive layer, or a transfer method in which a pressure-sensitive adhesive layer formed on the release surface is transferred to the support.

[0120] The thickness of the pressure-sensitive adhesive layer is not particularly limited and may be, for example, approximately 3 μm to 500 μm. From the viewpoint of impact resistance, in some embodiments, the thickness of the pressure-sensitive adhesive layer is suitably 5 μm or more, preferably 10 μm or more, and more preferably 15 μm or more. Furthermore, in some embodiments, the thickness of the pressure-sensitive adhesive layer may be, for example, 200 μm or less, and from the viewpoint of suppressing deformation of the pressure-sensitive adhesive layer, it is preferably 120 μm or less, and may be 100 μm or less, 70 μm or less, 50 μm or less, or 35 μm or less. With the pressure-sensitive adhesive sheet disclosed herein, in an embodiment having a pressure-sensitive adhesive layer with a thickness of, for example, 70 μm or less, it is possible to form a bond that is highly resistant to deformation and highly resistant to impact.

[0121] <Support> The pressure-sensitive adhesive sheet according to some embodiments may be in the form of a pressure-sensitive adhesive sheet with a support, which includes a support bonded to a pressure-sensitive adhesive layer. The material of the support is not particularly limited and can be appropriately selected depending on the intended use and manner of use of the pressure-sensitive adhesive sheet. Non-limiting examples of usable supports include resin films such as polyolefin films primarily composed of polyolefins such as polypropylene and ethylene-propylene copolymers, polyester films primarily composed of polyesters such as polyethylene terephthalate and polybutylene terephthalate, and polyvinyl chloride films primarily composed of polyvinyl chloride; foam sheets made of foams such as polyurethane foam, polyethylene foam, and polychloroprene foam; woven and nonwoven fabrics made by spinning various fibrous materials (natural fibers such as hemp and cotton, synthetic fibers such as polyester and vinylon, and semi-synthetic fibers such as acetate), either alone or in combination; papers such as Japanese paper, fine paper, kraft paper, and crepe paper; and metal foils such as aluminum foil and copper foil. Supports having a composite structure of these materials are also possible. Examples of such a composite structure support include a support having a structure in which a metal layer (e.g., a metal foil, a continuous or discontinuous metal sputter layer, a metal vapor deposition layer, a metal plating layer, etc.) or a metal oxide layer is laminated with the resin film, and a resin sheet reinforced with inorganic fibers such as glass cloth. The support may be an optical member (e.g., an optical film) described below, or may be a transparent member formed from a transparent material (e.g., a transparent resin material, glass, etc.).

[0122] Various films (hereinafter also referred to as support films) can be preferably used as the support for the PSA sheet disclosed herein. The support film may be a porous film such as a foam film or a nonwoven fabric sheet, a nonporous film, or a film having a structure in which a porous layer and a nonporous layer are laminated. In some embodiments, the support film preferably includes a base film that is an independently shape-retaining (self-supporting or independent) resin film. Here, the term "resin film" refers to a resin film with a nonporous structure that is typically substantially bubble-free (void-free). Therefore, the resin film is a concept that is distinct from foam films and nonwoven fabrics. The resin film may have a single-layer structure or a multi-layer structure of two or more layers (e.g., a three-layer structure).

[0123] Examples of resin materials that can be used to form the resin film include polyesters, polyolefins, polycycloolefins derived from monomers having an alicyclic structure such as norbornene, polyamides (PA) such as nylon 6, nylon 66, and partially aromatic polyamides, polyimides (PI), polyamideimides (PAI), polyetheretherketone (PEEK), polyethersulfone (PES), polyphenylene sulfide (PPS), polycarbonate (PC), polyurethane (PU), ethylene-vinyl acetate copolymers (EVA), fluororesins such as polystyrene, polyvinyl chloride, polyvinylidene chloride, and polytetrafluoroethylene (PTFE), acrylic resins such as polymethyl methacrylate, cellulose-based polymers such as diacetyl cellulose and triacetyl cellulose, vinyl butyral-based polymers, arylate-based polymers, polyoxymethylene-based polymers, and epoxy-based polymers. The resin film may be formed using a resin material containing one of these resins alone, or a resin material containing a blend of two or more of them. The resin film may be unstretched or stretched (for example, uniaxially or biaxially stretched).

[0124] Suitable examples of resin materials constituting the resin film include polyester-based resin, PPS resin, and polyolefin-based resin. Here, polyester-based resin refers to a resin containing more than 50% by weight of polyester. Similarly, PPS resin refers to a resin containing more than 50% by weight of PPS, and polyolefin-based resin refers to a resin containing more than 50% by weight of polyolefin.

[0125] The polyester resin is typically a polyester resin containing, as a main component, a polyester obtained by polycondensation of a dicarboxylic acid and a diol. Specific examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polybutylene naphthalate.

[0126] The polyolefin resin can be a single polyolefin or a combination of two or more polyolefins. The polyolefin can be, for example, an α-olefin homopolymer, a copolymer of two or more α-olefins, or a copolymer of one or more α-olefins with other vinyl monomers. Specific examples include polyethylene (PE), polypropylene (PP), poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene copolymers such as ethylene-propylene rubber (EPR), ethylene-propylene-butene copolymers, ethylene-butene copolymers, ethylene-vinyl alcohol copolymers, and ethylene-ethyl acrylate copolymers. Both low-density (LD) and high-density (HD) polyolefins can be used. Examples of polyolefin resin films include unstretched polypropylene (CPP) film, biaxially oriented polypropylene (OPP) film, low-density polyethylene (LDPE) film, linear low-density polyethylene (LLDPE) film, medium-density polyethylene (MDPE) film, high-density polyethylene (HDPE) film, polyethylene (PE) film made by blending two or more types of polyethylene (PE), and PP / PE blend film made by blending polypropylene (PP) and polyethylene (PE).

[0127] Specific examples of resin films that can be preferably used as the support include PET film, PEN film, PPS film, PEEK film, CPP film, and OPP film. Preferred examples from the viewpoint of strength include PET film, PEN film, PPS film, and PEEK film. Preferred examples from the viewpoints of availability, dimensional stability, optical properties, etc. include PET film.

[0128] The resin film may contain known additives such as light stabilizers, antioxidants, antistatic agents, colorants (dyes, pigments, etc.), fillers, slip agents, antiblocking agents, etc. The amount of additives added is not particularly limited and can be set appropriately depending on the application of the PSA sheet, etc.

[0129] The method for producing the resin film is not particularly limited, and for example, conventionally known general resin film forming methods such as extrusion molding, inflation molding, T-die casting, and calendar roll molding can be appropriately used.

[0130] The support may be a support film substantially composed of such a resin film. Alternatively, the support may be a support film including an auxiliary layer in addition to the resin film. The auxiliary layer may be disposed on the pressure-sensitive adhesive layer side of the resin film, on the side opposite the pressure-sensitive adhesive layer, or on both sides of the resin film. Examples of the auxiliary layer include an optical property adjusting layer (e.g., a coloring layer, an anti-reflection layer), a decorative layer (e.g., a printing layer, a laminate layer, a continuous or discontinuous metal layer, a continuous or discontinuous metal oxide layer, etc.) that imparts a desired appearance to the support or pressure-sensitive adhesive sheet, a conductive layer, an antistatic layer, an undercoat layer, a release layer, etc.

[0131] The thickness of the support is not particularly limited and can be selected depending on the purpose and mode of use of the PSA sheet. The thickness of the support may be, for example, 1000 μm or less, 500 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, 25 μm or less, 10 μm or less, or 5 μm or less. As the thickness of the support decreases, the flexibility of the PSA sheet and its ability to conform to the surface shape of the adherend tend to improve. Furthermore, from the viewpoint of handleability and processability, the thickness of the support may be, for example, 2 μm or more, or may be greater than 5 μm or greater than 10 μm. In some embodiments, the thickness of the support may be, for example, 20 μm or more, 35 μm or more, or 55 μm or more.

[0132] The surface of the support that is to be bonded to the pressure-sensitive adhesive layer may be subjected to conventional surface treatments such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, application of a primer, and antistatic treatment, as necessary. Such surface treatments may be intended to improve the adhesion between the support and the pressure-sensitive adhesive layer, in other words, the anchoring ability of the pressure-sensitive adhesive layer to the support. The composition of the primer is not particularly limited and can be appropriately selected from known primers. The thickness of the primer layer is not particularly limited, but is generally approximately 0.01 μm to 1 μm, and preferably approximately 0.1 μm to 1 μm.

[0133] In a single-sided pressure-sensitive adhesive sheet with a support, the side of the support opposite to the side bonded to the pressure-sensitive adhesive layer (hereinafter also referred to as the back side) may be subjected to a conventionally known surface treatment such as a release treatment, an adhesion or tackiness improving treatment, or an antistatic treatment, as necessary. For example, by surface treating the back side of the support with a release agent, the unwinding force of the pressure-sensitive adhesive sheet wound into a roll can be reduced. Examples of release agents that can be used include silicone-based release agents, long-chain alkyl-based release agents, olefin-based release agents, fluorine-based release agents, fatty acid amide-based release agents, molybdenum sulfide, and silica powder.

[0134] <Laminate manufacturing method> The pressure-sensitive adhesive sheet disclosed herein can be preferably used in an embodiment in which it is attached to an adherend by a method including laminating the sheet to the adherend and then photocuring the pressure-sensitive adhesive layer. By laminating the pressure-sensitive adhesive sheet to the adherend, an adherend on which the pressure-sensitive adhesive sheet is laminated is formed. By photocuring the pressure-sensitive adhesive layer of this pressure-sensitive adhesive sheet, a laminate is obtained that includes the pressure-sensitive adhesive sheet with the cured pressure-sensitive adhesive layer and the adherend. Therefore, this specification provides a laminate manufacturing method that includes, in this order, laminating any of the pressure-sensitive adhesive sheets disclosed herein to an adherend, and irradiating the pressure-sensitive adhesive sheet with ultraviolet light to photocure the pressure-sensitive adhesive layer.

[0135] <Application> The pressure-sensitive adhesive sheets disclosed herein can be used for applications such as fixing, joining, molding, decorating, protecting, and supporting components constituting various products. The material constituting at least the surface of the component can be, for example, glass such as alkali glass or alkali-free glass; metal materials such as stainless steel (SUS) and aluminum; or resin materials such as acrylic resin, ABS resin, polycarbonate resin, and polystyrene resin. The component can be, for example, a component constituting various mobile devices (portable devices), automobiles, home appliances, etc. Furthermore, the surface of the component to which the pressure-sensitive adhesive sheet is attached can be a painted surface with an acrylic, polyester, alkyd, melamine, urethane, acid-epoxy crosslinked paint, or a composite of these (e.g., acrylic-melamine, alkyd-melamine), or a plated surface such as a zinc-plated steel sheet. Furthermore, the component can be any of the support films exemplified as materials that can be used as a support (e.g., a resin film, or a support film having a continuous or discontinuous inorganic layer (which can be a metal layer, a metal oxide layer, etc.) on a resin film). The pressure-sensitive adhesive sheet disclosed herein can be, for example, a component of a member with a pressure-sensitive adhesive sheet in which the member is bonded to at least one surface of the pressure-sensitive adhesive layer that constitutes the pressure-sensitive adhesive layer.

[0136] An example of a preferred application is an optical application. More specifically, the pressure-sensitive adhesive sheet disclosed herein can be preferably used as an optical pressure-sensitive adhesive sheet used for bonding optical members (for bonding optical members) or for manufacturing products (optical products) using the optical members.

[0137] The optical member refers to a member having optical properties (e.g., polarization, light refraction, light scattering, light reflectivity, light transmittance, light absorption, light diffraction, optical rotation, visibility, etc.). The optical member is not particularly limited as long as it has optical properties, and examples thereof include components constituting devices (optical devices) such as display devices (image display devices) and input devices, or components used in these devices, such as polarizing plates, wavelength plates, retardation plates, optical compensation films, brightness enhancement films, light guide plates, reflective films, anti-reflection films, hard coat (HC) films, impact absorbing films, antifouling films, photochromic films, light control films, transparent conductive films (ITO films), design films, decorative films, surface protection plates, prisms, lenses, color filters, transparent substrates, and further components in which these are laminated (these may be collectively referred to as "functional films"). The above "plate" and "film" respectively include plate-like, film-like, sheet-like and other forms. For example, "polarizing film" includes "polarizing plate", "polarizing sheet", and the like.

[0138] Examples of the display device include a liquid crystal display device, an organic EL (electroluminescence) display device, a PDP (plasma display panel), electronic paper, etc. Examples of the input device include a touch panel.

[0139] The optical member is not particularly limited, but examples thereof include members (e.g., sheet-, film-, or plate-shaped members) made of glass, acrylic resin, polycarbonate, polyethylene terephthalate, metal thin film, etc. In this specification, the term "optical member" also includes members (such as design films, decorative films, and surface protection films) that serve to decorate or protect a display device or input device while maintaining its visibility.

[0140] The embodiment of bonding optical members using the pressure-sensitive adhesive sheet disclosed herein is not particularly limited, and may be, for example, (1) a mode in which optical members are bonded to each other via the pressure-sensitive adhesive sheet disclosed herein, (2) a mode in which an optical member is bonded to a member other than an optical member via the pressure-sensitive adhesive sheet disclosed herein, or (3) a mode in which the pressure-sensitive adhesive sheet disclosed herein includes an optical member and the pressure-sensitive adhesive sheet is bonded to an optical member or a member other than an optical member. In the above-mentioned embodiment (3), the pressure-sensitive adhesive sheet including an optical member may be, for example, a pressure-sensitive adhesive sheet whose support is an optical member (e.g., an optical film). Such a pressure-sensitive adhesive sheet including an optical member as a support may also be understood as a pressure-sensitive adhesive optical member (e.g., a pressure-sensitive adhesive optical film). Furthermore, when the pressure-sensitive adhesive sheet disclosed herein is a pressure-sensitive adhesive sheet having a support and the above-mentioned functional film is used as the support, the pressure-sensitive adhesive sheet disclosed herein may also be understood as a "pressure-sensitive adhesive functional film" having the pressure-sensitive adhesive layer disclosed herein on at least one side of the functional film.

[0141] The matters disclosed in this specification include the following: (1) A pressure-sensitive adhesive sheet including a pressure-sensitive adhesive layer, The pressure-sensitive adhesive layer contains a polymer (A) and a photoreactive monomer (B), The photoreactive monomer (B) includes a compound B1 having two or more ethylenically unsaturated groups, The pressure-sensitive adhesive sheet, wherein the compound B1 has a molecular weight (functional group equivalent) per ethylenically unsaturated group of 100 g / mol or more. (2) The pressure-sensitive adhesive sheet according to (1) above, wherein the compound B1 contains a ring structure in the molecule. (3) The pressure-sensitive adhesive sheet according to (2) above, wherein the compound B1 contains at least one structure selected from the group consisting of a bisphenol A structure, a bisphenol F structure, and a bisphenol E structure in the molecule. (4) The pressure-sensitive adhesive sheet according to (2) or (3) above, wherein the compound B1 contains an aliphatic ring structure as the ring structure. (5) The pressure-sensitive adhesive sheet according to any one of (1) to (4) above, wherein the compound B1 contains, in the molecule, at least one structure selected from the group consisting of a hydroxyl group and an amino group. (6) The pressure-sensitive adhesive sheet according to any one of (1) to (5) above, wherein the content of the compound B1 in the pressure-sensitive adhesive layer is 0.5 parts by weight or more and 60 parts by weight or less per 100 parts by weight of the polymer (A). (7) The pressure-sensitive adhesive sheet according to any one of (2) to (5), wherein the pressure-sensitive adhesive layer contains, as the photoreactive monomer (B), the compound B1 and a compound B2 having two or more functional groups and not having a ring structure in the molecule. (8) The pressure-sensitive adhesive sheet according to (7) above, wherein the functional group equivalent of the compound B2 is smaller than the functional group equivalent of the compound B1. (9) The pressure-sensitive adhesive sheet according to (7) or (8) above, wherein the functional group equivalent of the compound B2 is 400 g / mol or less. (10) The pressure-sensitive adhesive sheet according to any one of (7) to (9) above, wherein the content of the compound B2 in the pressure-sensitive adhesive layer is 25 parts by weight or less per 100 parts by weight of the polymer (A). (11) The pressure-sensitive adhesive sheet according to any one of (1) to (10), wherein the content of the photoreactive monomer (B) in the pressure-sensitive adhesive layer is 1 part by weight or more and 80 parts by weight or less per 100 parts by weight of the polymer (A). (12) The pressure-sensitive adhesive sheet according to any one of (1) to (11) above, wherein the polymer (A) is an acrylic polymer. (13) The pressure-sensitive adhesive sheet according to (12) above, wherein the monomer component constituting the acrylic polymer includes a monomer having a nitrogen atom-containing ring. (14) The pressure-sensitive adhesive sheet according to any one of (1) to (13) above, wherein the glass transition temperature of the polymer (A) is -45°C or higher and lower than 0°C. (15) The pressure-sensitive adhesive sheet according to any one of (1) to (14) above, wherein the pressure-sensitive adhesive layer is crosslinked with a crosslinking agent. (16) The pressure-sensitive adhesive sheet according to any one of (1) to (15) above, wherein the pressure-sensitive adhesive layer contains a photopolymerization initiator. (17) The pressure-sensitive adhesive sheet according to any one of (1) to (14) above, wherein the pressure-sensitive adhesive layer contains a silane coupling agent. (18) The pressure-sensitive adhesive sheet according to any one of (1) to (17) above, which has a tensile modulus of elasticity of 3.0 MPa or more as measured by the tensile test. (19) Impact resistance measured by the above shear impact test is 2.0 J / (10 mm) 2 The pressure-sensitive adhesive sheet according to any one of (1) to (18) above. (20) The pressure-sensitive adhesive sheet according to any one of (1) to (19) above, which has a peel strength measured by the peel test of 1.0 N / 10 mm or more.

[0142] (21) A polymer (A) and a photoreactive monomer (B), The photoreactive monomer (B) includes a compound B1 having two or more ethylenically unsaturated groups, The pressure-sensitive adhesive composition, wherein the compound B1 has a molecular weight (functional group equivalent) per ethylenically unsaturated group of 100 g / mol or more. (22) The pressure-sensitive adhesive sheet according to (21) above, wherein the compound B1 contains a ring structure in the molecule. (23) The pressure-sensitive adhesive composition according to (22), wherein the compound B1 contains at least one structure selected from the group consisting of a bisphenol A structure, a bisphenol F structure, and a bisphenol E structure in the molecule. (24) The pressure-sensitive adhesive composition according to (2) or (23) above, wherein the compound B1 contains an aliphatic ring structure as the ring structure. (25) The pressure-sensitive adhesive composition according to any one of (21) to (24) above, wherein the compound B1 contains, in the molecule, at least one structure selected from the group consisting of a hydroxyl group and an amino group. (26) The pressure-sensitive adhesive composition according to any one of (21) to (25) above, wherein the content of the compound B1 in the pressure-sensitive adhesive layer is 0.5 parts by weight or more and 60 parts by weight or less per 100 parts by weight of the polymer (A). (27) The pressure-sensitive adhesive composition according to any one of (22) to (25), wherein the pressure-sensitive adhesive layer contains, as the photoreactive monomer (B), the compound B1 and a compound B2 having two or more functional groups and not having a ring structure in the molecule. (28) The pressure-sensitive adhesive composition according to (27) above, wherein the functional group equivalent of the compound B2 is smaller than the functional group equivalent of the compound B1. (29) The pressure-sensitive adhesive composition according to (27) or (28) above, wherein the functional group equivalent of the compound B2 is 400 g / mol or less. (30) The pressure-sensitive adhesive composition according to any one of (27) to (29) above, wherein the content of the compound B2 in the pressure-sensitive adhesive layer is 25 parts by weight or less per 100 parts by weight of the polymer (A). (31) The pressure-sensitive adhesive composition according to any one of (21) to (30), wherein the content of the photoreactive monomer (B) in the pressure-sensitive adhesive layer is 1 part by weight or more and 80 parts by weight or less per 100 parts by weight of the polymer (A). (32) The pressure-sensitive adhesive composition according to any one of (21) to (31) above, wherein the polymer (A) is an acrylic polymer. (33) The pressure-sensitive adhesive composition according to (32) above, wherein the monomer component constituting the acrylic polymer includes a monomer having a nitrogen atom-containing ring. (34) The pressure-sensitive adhesive composition according to any one of (21) to (33) above, wherein the glass transition temperature of the polymer (A) is −45° C. or higher and lower than 0° C. (35) The pressure-sensitive adhesive composition according to any one of (21) to (34) above, which contains a crosslinking agent. (36) The pressure-sensitive adhesive composition according to any one of (21) to (35) above, which contains a photopolymerization initiator. (37) The pressure-sensitive adhesive composition according to any one of (21) to (36) above, which contains a silane coupling agent. (38) The pressure-sensitive adhesive composition according to any one of (21) to (37) above, which is used to form a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of (1) to (20). (39) A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition according to any one of (21) to (37) above.

[0143] (40) A pressure-sensitive adhesive sheet including a pressure-sensitive adhesive layer, The tensile modulus measured by the tensile test is 3.0 MPa or more, and the impact resistance measured by the shear impact test is 2.0 J / (10 mm) 2 That's it, adhesive sheet. (41) The pressure-sensitive adhesive sheet according to (40) above, which has a peel strength measured by the peel test of 1.0 N / 10 mm or more. (42) The pressure-sensitive adhesive sheet according to any one of (40) to (41) above, wherein the pressure-sensitive adhesive layer is the pressure-sensitive adhesive layer according to any one of (1) to (17) above. (43) The pressure-sensitive adhesive sheet according to any one of (40) to (42) above, wherein the pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive composition according to any one of (21) to (37) above.

[0144] (44) The pressure-sensitive adhesive composition according to any one of (21) to (37) above, wherein the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition and having a thickness selected from the range of 5 μm to 200 μm (preferably the range of 15 μm to 25 μm) (for example, a pressure-sensitive adhesive layer having a thickness of 20 μm) has a tensile modulus of 3.0 MPa or more, as measured by the tensile test. (45) The pressure-sensitive adhesive composition has an impact resistance of 2.0 J / (10 mm) when measured by the shear impact test for a pressure-sensitive adhesive layer having the thickness described above formed from the pressure-sensitive adhesive composition. 2 The pressure-sensitive adhesive composition according to (44) above. (46) The pressure-sensitive adhesive composition according to (44) or (45) above, wherein a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition and having the above thickness has a peel strength of 1.0 N / 10 mm or more as measured by the peel test. (47) A film member with a pressure-sensitive adhesive sheet, comprising the pressure-sensitive adhesive sheet according to any one of (1) to (20) and (40) to (43) above, and a film member bonded to the pressure-sensitive adhesive layer. (48) A pressure-sensitive adhesive sheet according to any one of (1) to (20) and (40) to (43) above is attached to an adherend; irradiating the pressure-sensitive adhesive sheet with ultraviolet light to photocure the pressure-sensitive adhesive layer; A method for manufacturing a laminate, comprising the steps of:

[0145] Several examples of the present invention will be described below, but it is not intended that the present invention be limited to those shown in these examples. In the following description, "parts" and "%" are by weight unless otherwise specified.

[0146] <Synthesis of Polymer (A)> (Polymer P1) A reaction vessel equipped with a condenser, nitrogen inlet, thermometer, and stirrer was charged with the following monomer components: 60 parts n-butyl acrylate (BA), 6 parts cyclohexyl acrylate (CHA), 18 parts N-vinyl-2-pyrrolidone (NVP), 1 part isostearyl acrylate (iSTA), and 15 parts 4-hydroxybutyl acrylate (4HBA); 0.085 parts α-thioglycerol as a chain transfer agent; and 122 parts ethyl acetate as a polymerization solvent. 0.2 parts 2,2'-azobisisobutyronitrile (AIBN) was added as a thermal polymerization initiator, and solution polymerization was carried out under a nitrogen atmosphere to obtain a solution of polymer P1. The weight-average molecular weight (Mw) of polymer P1 was 300,000. The Tg of polymer P1 calculated from the composition of the above monomer components was -33°C.

[0147] (Polymer P2) A reaction vessel equipped with a condenser, nitrogen inlet, thermometer, and stirrer was charged with 64.5 parts of BA, 6 parts of CHA, 9.6 parts of NVP, 5 parts of iSTA, and 14.9 parts of 4HBA as monomer components, 0.07 parts of α-thioglycerol as a chain transfer agent, and 122 parts of ethyl acetate as a polymerization solvent. 0.2 parts of AIBN were added as a thermal polymerization initiator, and solution polymerization was carried out under a nitrogen atmosphere to obtain a solution of polymer P2. The Mw of polymer P2 was 600,000. The Tg of polymer P2 calculated from the composition of the above monomer components was -39 ° C.

[0148] <Preparation of Pressure-Sensitive Adhesive Composition> (Example 1) The solution of polymer P1 obtained above was mixed with 0.05 parts by solids of an isocyanate-based crosslinking agent X1 (trimethylolpropane / xylylene diisocyanate adduct (manufactured by Mitsui Chemicals, Inc., trade name: Takenate D-110N, solid content 75%), 0.01 parts by solids of dioctyltin dilaurate (manufactured by Tokyo Fine Chemicals, trade name: Envirizer OL-1) as a crosslinking accelerator, and acetylacetone as a crosslinking retarder, per 100 parts by solids of the monomer components used in preparing the solution. A solvent-based pressure-sensitive adhesive composition according to Example 1 was prepared by adding 4 parts of methyl acrylate (manufactured by IGM Regins, trade name: Omnirad 184) as a photopolymerization initiator, 0.4 parts of methyl acrylate (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM-403) as a silane coupling agent, 0.3 parts of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM-403) as a silane coupling agent, 8 parts of dipentaerythritol hexaacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name: A-DPH) and 12 parts of tricyclodecane dimethanol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name: A-DCP) as photoreactive monomers, and 0.72 parts of 1-hydroxycyclohexyl-phenyl-ketone (manufactured by IGM Regins, trade name: Omnirad 184) as a photopolymerization initiator and mixing them uniformly.

[0149] (Examples 2-3, 5-12) The solvent-based pressure-sensitive adhesive compositions of each example were prepared in the same manner as in the preparation of the solvent-based pressure-sensitive adhesive composition of Example 1, except that the type and amount of the photoreactive monomer, the amount of the crosslinking agent, and the amount of the photopolymerization initiator were as shown in Tables 1 and 2.

[0150] (Example 4) The solvent-based pressure-sensitive adhesive composition of this example was prepared in the same manner as in Example 3, except that the isocyanate-based crosslinking agent X1 was replaced with an isocyanate-based crosslinking agent X2 (trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name: Coronate L)).

[0151] (Example 13) The solvent-based pressure-sensitive adhesive composition of this example was prepared in the same manner as in the preparation of the solvent-based pressure-sensitive adhesive composition of Example 10, except that the solution of polymer P2 was used instead of the solution of polymer P1.

[0152] <Preparation of adhesive sheet> The solvent-based pressure-sensitive adhesive composition of each example prepared above was applied to the release surface of a 38 μm-thick release film R1 (Mitsubishi Plastics, Inc., MRF#38), one side of which was a polyester film, and dried at 130°C for 3 minutes to form a 20 μm-thick photocurable pressure-sensitive adhesive layer (supportless double-sided pressure-sensitive adhesive sheet). The surface of this pressure-sensitive adhesive layer was protected by bonding the release surface of a 38 μm-thick release film R2 (Mitsubishi Plastics, Inc., MRE#38), one side of which was a polyester film. In this way, a laminate sheet was obtained in which release film R1, a supportless double-sided pressure-sensitive adhesive sheet, and release film R2 were laminated in this order.

[0153] <Measurement and Evaluation> The resulting pressure-sensitive adhesive sheets were subjected to the following measurements and evaluations. (1) Measurement of tensile modulus The laminated sheet according to each example (a laminated sheet having a support-less adhesive layer sandwiched between two transparent release films) was exposed to light using a high-pressure mercury lamp at an illumination intensity of 300 mW / cm 2 , cumulative light intensity 3000mJ / cm 2 After irradiating the laminated sheet with UV light under these conditions and aging it at 50°C for 48 hours, the laminated sheet was cut into a size of 10 mm wide and 150 mm long. At 23°C and 50% RH, the release films R1 and R2 were peeled off to expose the adhesive layer. A tensile test was performed on the specimen using a tensile tester (Minebea Co., Ltd., universal tension and compression tester, model name "Tension and Compression Tester, TCM-1kNB") at a chuck distance of 120 mm and a tensile speed of 50 mm / min to obtain an SS curve. The tensile modulus [MPa] was calculated from the initial slope (the elastic deformation region of the SS curve, specifically, the slope in the range where the displacement is less than approximately 5%). Measurements were performed three times (i.e., n = 3), and the arithmetic mean values ​​are shown in Tables 1 and 2.

[0154] (2) Impact resistance measurement A shear impact test was carried out using a pendulum-type adhesive shear impact tester based on JIS K6855. For the measurement sample, the laminate sheet according to each example was cut into a 10 mm square, the release film R1 was peeled off to expose the first surface of the adhesive layer, and the first surface was attached to the center of a 25 mm square, 1.7 mm thick chemically strengthened glass plate (manufactured by Corning Incorporated). After that, the release film R2 was peeled off, and the second surface of the adhesive layer was attached to the center of a 40 mm square stainless steel plate (SUS304BA plate) and pressed with a load of 5 N for 10 seconds. Then, autoclaving (50°C, 0.5 MPa, 15 minutes) was carried out, and the irradiance was 300 mW / cm using a high-pressure mercury lamp from the glass plate side. 2 , cumulative light intensity 3000mJ / cm 2 After irradiating with ultraviolet light under the conditions of (1), the film was aged at 50°C for 48 hours and then used. The measurement sample was fixed with the stainless steel plate facing downwards, and the impact resistance [J / (10 mm)] was measured by measuring the absorbed energy [J] when hitting the outer periphery of the glass plate with a hammer at a hammer energy of 2.75 J and a hammer speed (impact speed) of 3.5 m / s in an environment of 23°C and 50% RH. 2 The measurements were carried out three times, and the arithmetic mean values ​​are shown in Tables 1 and 2.

[0155] (3) Peel strength The laminate sheet according to each example was cut to a size of 10 mm in width and 150 mm in length to prepare a test piece, and the first surface of the adhesive layer of the test piece was pressed against a glass plate (an alkali glass plate manufactured by Matsunami Glass Industry Co., Ltd., prepared by the float method, 1.35 mm thick, with a polished blue edge) by rolling a 2 kg rubber roller back and forth once. After autoclaving (50°C, 0.5 MPa, 15 minutes), the test piece was heated at an illuminance of 300 mW / cm using a high-pressure mercury lamp from the glass plate side. 2 , cumulative light intensity 3000mJ / cm 2The specimen was irradiated with ultraviolet light under the following conditions. After aging at 50°C for 48 hours, the specimen was peeled from the glass plate at a peel angle of 180° and a pulling rate of 60 mm / min using a tensile tester (Minebea Co., Ltd., universal tension and compression tester, model name "Tension and Compression Tester, TCM-1kNB") in an environment of 23°C and 50% RH, and the peel strength was measured. The measurement was performed three times, and the arithmetic average values ​​are shown in Tables 1 and 2.

[0156] The haze values ​​of the pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets of Examples 1, 6, 8, and 11 were measured by the method described above and were all 0.5% or less. The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets of Examples 6 and 8 exhibited particularly good transparency.

[0157] [Table 1]

[0158] [Table 2]

[0159] The photoreactive monomers used in Examples 1 to 13 are as follows: In Tables 1 and 2, each photoreactive monomer is shown by its abbreviation. DPHA: Dipentaerythritol hexaacrylate (Shin-Nakamura Chemical Co., Ltd., product name "A-DPH", functional group equivalent weight 96) A-DCP: Tricyclodecane dimethanol diacrylate (Shin-Nakamura Chemical Co., Ltd., trade name "A-DCP", functional group equivalent weight 152) #540: Bisphenol A diglycidyl ether acrylic acid adduct (Osaka Organic Chemical Industry, trade name "Biscoat #540", functional group equivalent weight 250) R115F: Bisphenol A diglycidyl ether acrylic acid adduct (Nippon Kayaku, trade name "KAYARAD R-115F", functional group equivalent 450) #700HV: Bisphenol A ethylene oxide 3.8 mole adduct diacrylate (Osaka Organic Chemical Industry, trade name "Biscoat #700HV", functional group equivalent weight 350) E3703: Amine-modified bisphenol A epoxy diacrylate (Daicel Allnex, trade name "EBECRYL 3703", functional group equivalent weight 425) APG400: Polypropylene glycol #400 diacrylate (Shin-Nakamura Chemical Co., Ltd., trade name "APG-400", functional group equivalent weight 268)

[0160] The pressure-sensitive adhesive sheets of Examples 1 to 9 shown in Table 1 had excellent deformation resistance due to their high tensile modulus and exhibited high impact resistance. On the other hand, the pressure-sensitive adhesive sheets of Examples 10, 12, and 13 shown in Table 2 had low deformation resistance, and the pressure-sensitive adhesive sheet of Example 11 had low peel strength.

[0161] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above. [Explanation of symbols]

[0162] 1,2 Adhesive sheet 10 adhesive layer 10A One surface (adhesive side) 10B Other surface 20 Support 20A front page 20B Second side (back) 30, 31, 32 Release liner 50 adhesive sheets with release liner 70 Film materials 100 Adhesive sheet attached material

Claims

1. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer contains an acrylic polymer (A) and a photoreactive monomer (B), The photoreactive monomer (B) includes a compound B1 having a ring structure and two or more ethylenically unsaturated groups in the molecule, and a compound B2 having no ring structure in the molecule but two or more ethylenically unsaturated groups, and the functional group equivalent FE of the compound B1 １ The functional group equivalent FE of the compound B2 ２ The ratio (FE ２ / FE １ ) is 0.5 or less, The elastic modulus measured by the following tensile test is 3.0 MPa or more, and the impact resistance measured by the following shear impact test is 2.0 J / (10 mm) ２ That's it, adhesive sheet. [Tensile test] The pressure-sensitive adhesive layer was exposed to an illuminance of 300 mW / cm ２ , cumulative light intensity 3000 mJ / cm ２ After aging at 50°C for 48 hours, the pressure-sensitive adhesive layer is cut into a size of 10 mm wide and 150 mm long to prepare a test piece. A tensile test is performed on the test piece using a tensile tester under conditions of 23°C and 50% RH, with a chuck distance of 120 mm and a tensile speed of 50 mm / min, to obtain a stress-displacement curve, and the elastic modulus [MPa] is calculated from the initial slope. [Shear impact test] A shear impact test is performed using a pendulum-type adhesive shear impact tester based on JIS K 6855. A measurement sample is prepared by bonding a first surface of the pressure-sensitive adhesive layer, 10 mm square, to the center of a 25 mm square, 1.7 mm thick chemically strengthened glass plate, and then bonding a second surface of the pressure-sensitive adhesive layer to the center of a 40 mm square stainless steel plate (SUS304BA plate) under pressure of 5 N for 10 seconds, followed by autoclaving (50°C, 0.5 MPa, 15 minutes), and then applying an illuminance of 300 mW / cm from the glass plate side. ２ , cumulative light intensity 3000 mJ / cm ２ After irradiating with ultraviolet light under the conditions of (1), the film is aged at 50° C. for 48 hours and then used. The measurement sample was fixed with the stainless steel plate facing downward, and a hammer was applied to the outer peripheral side surface of the glass plate under conditions of a hammer energy of 2.75 J and a hammer speed of 3.5 m / s in an environment of 23°C and 50% RH, and the absorbed energy [J] was measured to determine the impact resistance [J / (10 mm)]. ２ ] is required.

2. The pressure-sensitive adhesive sheet according to claim 1, which has a peel strength of 1.0 N / 10 mm or more as measured by the following peel test. [Peel test] The pressure-sensitive adhesive sheet was cut into a size of 10 mm in width and 150 mm in length to prepare a test piece, which was then pressed onto a glass plate by rolling a 2 kg rubber roller back and forth once, and then autoclaved (50°C, 0.5 MPa, 15 minutes). After that, the test piece was exposed to an illuminance of 300 mW / cm from the glass plate side. ２ , cumulative light intensity 3000 mJ / cm ２ After aging at 50°C for 48 hours, the test piece is peeled from the glass plate using a tensile tester at a peel angle of 180° and a pulling rate of 60 mm / min in an environment of 23°C and 50% RH, and the peel strength is measured.

3. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the compound B1 has a molecular weight per ethylenically unsaturated group of 100 g / mol or more.

4. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer contains an acrylic polymer (A) and a photoreactive monomer (B), The photoreactive monomer (B) includes a compound B1 having a ring structure and two or more ethylenically unsaturated groups in the molecule, and a compound B2 having no ring structure in the molecule but two or more ethylenically unsaturated groups, and the functional group equivalent FE of the compound B1 １ The functional group equivalent FE of the compound B2 ２ The ratio (FE ２ / FE １ ) is 0.5 or less, The compound B1 has a molecular weight per ethylenically unsaturated group of 100 g / mol or more.

5. The pressure-sensitive adhesive sheet according to claim 4, which has an elastic modulus of 3.0 MPa or more as measured by the following tensile test. [Tensile test] The pressure-sensitive adhesive layer was exposed to an illuminance of 300 mW / cm ２ , cumulative light intensity 3000 mJ / cm ２ After aging at 50°C for 48 hours, the pressure-sensitive adhesive layer is cut into a size of 10 mm wide and 150 mm long to prepare a test piece. A tensile test is performed on the test piece using a tensile tester under conditions of 23°C and 50% RH, with a chuck distance of 120 mm and a tensile speed of 50 mm / min, to obtain a stress-displacement curve, and the elastic modulus is calculated from the initial slope.

6. Impact resistance measured by the following shear impact test is 2.0 J / (10 mm) ２ The pressure-sensitive adhesive sheet according to claim 4 or 5, wherein the pressure-sensitive adhesive sheet is as described above. [Shear impact test] A shear impact test is performed using a pendulum-type adhesive shear impact tester based on JIS K 6855. A measurement sample is prepared by bonding a first surface of the pressure-sensitive adhesive layer, 10 mm square, to the center of a 25 mm square, 1.7 mm thick chemically strengthened glass plate, and then bonding a second surface of the pressure-sensitive adhesive layer to the center of a 40 mm square stainless steel plate (SUS304BA plate) under pressure of 5 N for 10 seconds, followed by autoclaving (50°C, 0.5 MPa, 15 minutes), and then applying an illuminance of 300 mW / cm from the glass plate side. ２ , cumulative light intensity 3000 mJ / cm ２ After irradiating with ultraviolet light under the conditions of (1), the film is aged at 50° C. for 48 hours and then used. The measurement sample was fixed with the stainless steel plate facing downward, and a hammer was applied to the outer peripheral side surface of the glass plate under conditions of a hammer energy of 2.75 J and a hammer speed of 3.5 m / s in an environment of 23°C and 50% RH, and the absorbed energy [J] was measured to determine the impact resistance [J / (10 mm)]. ２ ] is required.

7. A film member with a pressure-sensitive adhesive sheet, comprising: the pressure-sensitive adhesive sheet according to any one of claims 1 to 6; and a film member bonded to the pressure-sensitive adhesive layer.

8. A pressure-sensitive adhesive sheet according to any one of claims 1 to 6 attached to an adherend; irradiating the pressure-sensitive adhesive sheet with ultraviolet light to photocure the pressure-sensitive adhesive layer; A method for manufacturing a laminate, comprising the steps of:

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