Adhesive, adhesive sheet, optical structural body, and display body

Abstract

This invention provides an adhesive containing an oxygen absorber for optical applications. When a laminate consisting of two 1.1 mm thick, 7.0 cm square soda-lime glass plates bonded together with a 250 μm thick adhesive layer formed by this adhesive is subjected to a durability condition of 100 hours in an atmosphere at 140°C, the chromaticity b of the adhesive layer before the durability condition, as defined by the CIE 1976 Lab colorimetric system, is set to b1, and the chromaticity b of the adhesive layer at the ends of the laminate after the durability condition, as defined by the CIE 1976 Lab colorimetric system, is set to b2. In this case, the absolute value of the ratio of b2 to b1 is 4.5 or less. According to this adhesive, yellowing at the ends of optical components can be suppressed.

Description

Technical Field

[0001] The present invention relates to adhesives and adhesive sheets, and optical structures and displays obtained using the adhesives and adhesive sheets. Background Technology

[0002] In recent years, various mobile electronic devices such as mobile phones, smartphones, and tablets have been equipped with displays, which use display modules containing liquid crystal elements, light-emitting diodes (LED elements), organic electroluminescent (organic EL) elements, etc.

[0003] In the displays described above, a protective panel is typically provided on the surface side of the display module. A gap is provided between the protective panel and the display module to prevent the deformed protective panel from colliding with the display module even if it deforms due to external force.

[0004] However, if the gaps, i.e. air layers, as described above exist, there will be problems such as large light reflection loss and reduced image quality caused by the refractive index difference between the protective panel and the air layer, as well as the refractive index difference between the air layer and the display module.

[0005] Therefore, a solution has been proposed to improve the image quality of the display by filling the gap between the protective panel and the display module with an adhesive layer (adhesive layer). For example, as an adhesive layer for filling the gap between the protective panel and the display module, Patent Document 1 discloses an adhesive layer with a shear storage modulus (G') of 1.0 × 10⁻⁶ at 25°C and 1 Hz. 5 Adhesive layers with a Pa value below 40% and a gel content of 40% or more.

[0006] In recent years, high durability has been particularly demanded for automotive applications. To meet such requirements, for example, Patent Document 2 discloses an optical adhesive comprising an acrylic copolymer (A) having a defined monomer composition and an isocyanate-based curing agent (B), and defining a ratio G'2 / G'1 of storage modulus at 175°C to storage modulus at 225°C. Existing technical documents Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2010-97070 Patent Document 2: Japanese Patent Application Publication No. 2023-102312 Summary of the Invention (a) Technical problems to be solved

[0008] However, if a display obtained using the adhesive layer described above is placed at high temperatures for an extended period, the adhesive layer may sometimes yellow at the ends of the display. The optical adhesive described in Patent Document 2 uses the degree of yellowing as a benchmark for heat resistance, but this yellowing is not judged based on the ends of the test piece.

[0009] The present invention was made in view of this actual situation, and its object is to provide an adhesive and adhesive sheet capable of suppressing yellowing at the ends of optical components, and an optical structure and display body capable of suppressing yellowing of the adhesive layer at the ends. (II) Technical Solution

[0010] To achieve the above objectives, firstly, the present invention provides an adhesive containing an oxygen absorber for optical applications. The adhesive is characterized in that, when a laminate consisting of two 1.1 mm thick, 7.0 cm square soda-lime glass plates bonded together with an adhesive layer of 250 μm thickness formed by the adhesive is placed under a durability condition of immersion in an atmosphere at 140°C for 100 hours, the adhesive layer before the durability condition is conformed to CIE (International Commission on Illumination) 1976L. a b The color b specified in the color system Let b be the value of b. 1, and the adhesive layer at the end of the laminate after the durability condition is determined by CIE1976L a b The color b specified in the color system Let b be the value of b. 2. At this time, the b 2 relative to b The absolute value of the ratio of 1 to 4.5 or less (Invention 1).

[0011] Second, the present invention provides an adhesive containing an oxygen absorber for optical applications. The adhesive is characterized in that, when a laminate consisting of two 1.1 mm thick, 7.0 cm square soda-lime glass plates bonded together with an adhesive layer of 250 μm thickness formed by the adhesive is subjected to a durability condition of immersion in an atmosphere at 140°C for 100 hours, the adhesive layer at the ends of the laminate after the durability condition is subjected to a CIE1976L standard. a b The color b specified in the color system Let b be the value of b. At time 2, the b The absolute value of 2 is less than 2.0 (Invention 2).

[0012] Third, the present invention provides an adhesive containing an oxygen absorber for optical applications, characterized in that, when a laminate consisting of two 1.1 mm thick, 7.0 cm square soda-lime glass plates bonded together with an adhesive layer of 250 μm thickness formed by the adhesive is subjected to a durability condition of immersion in an atmosphere at 140°C for 100 hours, the adhesive layer at the ends of the laminate after the durability condition is in CIE1976L... a b The color b specified in the color system Let b be the value of b. 2, and the adhesive layer in the central portion of the laminate after the durability condition is determined by CIE1976L a b The color b specified in the color system Let b be the value of b. 3. At this time, the b 2 relative to b The absolute value of the ratio of 3 is 2.5 or less (Invention 3).

[0013] By including an oxygen absorber in the adhesive of the above-mentioned inventions (Inventions 1-3), the oxygen absorber can deactivate oxygen in the adhesive, thereby suppressing the thermal oxidative degradation of the adhesive. In particular, the ends of optical components are easily exposed to oxygen and prone to thermal oxidative degradation; however, through the action of the oxygen absorber, thermal oxidative degradation can be effectively suppressed even at the ends of the optical components. As a result, yellowing of the ends of optical components bonded by the adhesive layer formed by the adhesive can be suppressed. Specifically, when the above-mentioned laminate is manufactured and placed under the above-mentioned durability conditions, yellowing of the ends after the durability conditions relative to the adhesive layer before the durability conditions can be suppressed (Invention 1), the degree of yellowing of the ends after the durability conditions can be suppressed to a low level (Invention 2), and yellowing of the ends after the durability conditions relative to the central portion after the durability conditions can be suppressed (Invention 3).

[0014] In the above inventions (Inventions 1 to 3), the oxygen absorbent is preferably a compound represented by the following general formula (I) (Invention 4). [Chemical Formula 1] In general formula (I), X and Y each independently represent chalcogen atoms, and R 1 R 2 R 7 and R 8Each independently represents any one of alkyl, alkenyl, aryl, and aralkyl groups having 1 to 6 carbon atoms, R 3 R 4 R 5 and R 6 Each of the following independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aryl group, or an aralkyl group. J represents a linking group consisting of an aliphatic hydrocarbon having 3 to 15 carbon atoms, wherein any carbon atom of the linking group may be optionally substituted with an oxygen atom, or the linking group may optionally have at least one substituent selected from the group consisting of a hydroxyl group, (meth)acryloyloxy group, styryloxy group, or an alkenyloxy group having 2 to 5 carbon atoms. n is any integer from 1 to 5. Furthermore, when multiple Y and R are present... 5 R 6 R 7 and R 8 When, they can be chosen to be different atoms or groups.

[0015] In the above inventions (Inventions 1 to 4), the oxygen absorbent is preferably a compound represented by the following general formula (II) (Invention 5). [Chemical Formula 2] In general formula (II), R 9 R represents a hydrogen atom or a methyl group. 10 R represents any one of hydroxyl, (meth)acryloyloxy, styryloxy, and olefinic groups having 2 to 5 carbon atoms. 11 R 12 R 13 and R 14 Each can independently represent any one of alkyl, alkenyl, aryl, and aralkyl groups having 1 to 6 carbon atoms.

[0016] In the above inventions (Inventions 1 to 5), the oxygen absorbent is preferably a compound represented by the following formula (III) (Invention 6). [Chemical Formula 3]

[0017] The adhesive used in the above inventions (Inventions 1-6) is preferably an acrylic adhesive (Invention 7).

[0018] In the above inventions (Inventions 1-7), the adhesive is preferably a (meth)acrylate polymer or its crosslinked product (Invention 8).

[0019] The adhesive used in the above inventions (Inventions 1-8) is preferably an adhesive that can be cured by active energy rays (Invention 9).

[0020] Fourth, the present invention provides an adhesive sheet having an adhesive layer for bonding two components together, characterized in that at least one of the components is an optical component, and the adhesive layer is composed of the adhesive (Invention 1-9) (Invention 10).

[0021] In the above invention (Invention 10), it is preferred that the adhesive sheet has two release tabs, and the adhesive layer is clamped by the release tabs in such a way that it contacts the release surfaces of the two release tabs (Invention 11).

[0022] Fifth, the present invention provides an optical component, which is an optical component formed by bonding at least two components together using an adhesive layer, characterized in that at least one of the components is an optical component, and the adhesive layer is formed by the adhesive (Invention 1-9) (Invention 12).

[0023] Sixth, the present invention provides a display body comprising: a display body component, another display body component, and an adhesive layer for bonding the one display body component and the other display body component together, wherein the display body is characterized in that the adhesive layer is formed from the adhesive layer of the adhesive sheet (Invention 10-11) (Invention 13).

[0024] In the above invention (Invention 13), it is preferred that both the one display body component and the other display body component are rigid plates (Invention 14). (III) Beneficial Effects

[0025] The adhesive and adhesive sheet of the present invention can suppress yellowing at the ends of optical components. Furthermore, the optical structure and display body of the present invention can suppress yellowing of the adhesive layer at the ends. Attached Figure Description

[0026] Figure 1 This is a cross-sectional view of an adhesive sheet according to one embodiment of the present invention. Figure 2 This is a cross-sectional view of a display body according to one embodiment of the present invention. Detailed Implementation

[0027] The following describes an embodiment of the present invention. [Adhesive] One embodiment of the adhesive of the present invention is used for optical applications and preferably contains an oxygen absorber. Furthermore, when a laminate consisting of two 1.1 mm thick, 7.0 cm square soda-lime glass plates bonded together with a 250 μm thick adhesive layer formed using the adhesive of this embodiment is subjected to a durability condition of immersion in an atmosphere at 140°C for 100 hours, the adhesive layer before the aforementioned durability condition is compared with CIE1976L... a b The color b specified in the color system Let b be the value of b. 1. The adhesive layer at the end of the laminate after the above-mentioned durability conditions is conformed to CIE1976L. a b The color b specified in the color system Let b be the value of b. 2. And the adhesive layer in the central portion of the laminate after the above-mentioned durability conditions is determined by CIE1976L. a b The color b specified in the color system Let b be the value of b. 3. At this point, the first: b 2 relative to b The ratio of 1 to (b) 2 / b 1) The absolute value is preferably below 4.5, second: b The absolute value of 2 is preferably less than 2.0. Third: b 2 relative to b The ratio of 3 (b) 2 / b 3) The absolute value is preferably 2.5 or less. Additionally, the chromaticity b in this specification... The determination method is shown in the experimental examples described below.

[0028] Here, the "adhesive layer" in the aforementioned "laminate formed by bonding adhesive layers" refers to an adhesive layer in the same state as the adhesive layer of the adhesive sheet when the adhesive is non-reactive energy radiation-curable. When the adhesive layer is reactive energy radiation-curable, it refers to an adhesive layer cured by reactive energy radiation after bonding. "Reactive energy radiation-cured adhesive layer" means that the adhesive layer has been completely cured by reactive energy radiation irradiation. Specifically, it means that when the reactive energy radiation-cured adhesive layer is further irradiated with reactive energy radiation using the same radiation dose (light intensity) as during reactive energy radiation curing, the increase rate of the gel fraction of the adhesive layer is less than 10%, and particularly less than 5%.

[0029] If the adhesive of this embodiment contains an oxygen absorber, the oxygen absorber can deactivate oxygen in the adhesive, thereby inhibiting thermal oxidative degradation of the adhesive. In particular, although the ends of optical components are easily exposed to oxygen and prone to thermal oxidative degradation, the oxygen absorber effectively inhibits thermal oxidative degradation even at the ends of the optical components. As a result, yellowing of the ends of optical components bonded by the adhesive layer formed by this adhesive can be suppressed. Specifically, when the above-described laminate is manufactured and placed under the above-described durability conditions, yellowing of the ends after the durability conditions relative to the adhesive layer before the durability conditions can be suppressed, or the degree of yellowing of the ends after the durability conditions can be reduced, or yellowing of the ends after the durability conditions relative to the central portion after the durability conditions can be suppressed.

[0030] Here, "end of the laminate" in this specification refers to a circular region with a radius of 2 mm, the center of which is located 3 mm inward from the central end face of any side of the laminate in the top view. Furthermore, "central part of the laminate" in this specification refers to a 10 mm square region with the top view center point as the same center point.

[0031] From the perspective of suppressing end yellowing, as mentioned above, b 2 / b The absolute value of 1 is preferably 4.5 or less, more preferably 3.0 or less, particularly preferably 2.5 or less, and even more preferably 2.0 or less. 2 / b The lower limit of the absolute value of 1 is preferably 1, but it is also preferably 1.1 or higher, and particularly preferably 1.2 or higher.

[0032] From the perspective of suppressing end yellowing, as mentioned above, b The absolute value of 2 is preferably less than 2.0, more preferably 1.6 or less, particularly preferably 1.2 or less, and even more preferably 1.0 or less. The lower limit of the absolute value of 2 is preferably 0 or more, more preferably 0.1 or more, particularly preferably 0.2 or more, and even more preferably 0.3 or more.

[0033] From the perspective of suppressing end yellowing, as mentioned above, b 2 / b The absolute value of 3 is preferably 2.5 or less, more preferably 2.2 or less, particularly preferably 2.0 or less, and even more preferably 1.8 or less. 2 / b The lower limit of the absolute value of 1 is preferably 1, but it is also preferably 1.1 or higher, and particularly preferably 1.2 or higher.

[0034] From the perspective of making the adhesive layer as colorless and transparent as possible, b 1 is preferably -10 to 10, more preferably -5 to 5, particularly preferably -1 to 1, and even more preferably -0.5 to 0.5.

[0035] Furthermore, from the perspective of making the adhesive layer as colorless and transparent as possible, and from the perspective of easily satisfying the aforementioned physical properties, b 3 is preferably -10 to 10, more preferably -5 to 5, particularly preferably -1 to 1, and even more preferably -0.5 to 0.5.

[0036] From the perspective of easily satisfying the above-mentioned physical properties, the oxygen absorbent of this embodiment is preferably a compound represented by the following general formula (I) (hereinafter sometimes referred to as "compound Q"). [Chemical Formula 1] In general formula (I), X and Y each independently represent a chalcogenide atom, and R 1 R 2 R 7 and R 8 Each independently represents any one of alkyl, alkenyl, aryl, and aralkyl groups having 1 to 6 carbon atoms, R 3 R 4 R 5 and R 6 Each of the following independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aryl group, or an aralkyl group. J represents a linking group consisting of an aliphatic hydrocarbon having 3 to 15 carbon atoms, wherein any carbon atom of the linking group may be optionally substituted with an oxygen atom, or the linking group may optionally have at least one substituent selected from the group consisting of a hydroxyl group, (meth)acryloyloxy group, styryloxy group, or an alkenyloxy group having 2 to 5 carbon atoms. n is any integer from 1 to 5. Furthermore, when multiple Y and R are present... 5 R 6 R 7 and R 8 When, they can be chosen to be different atoms or groups.

[0037] In general formula (I), from the perspective of the ease of obtaining raw materials, n is preferably 1 to 4, and more preferably 1 or 2.

[0038] In general formula (I), from the perspective of ease of manufacture of compound Q and improvement of oxygen absorption performance, X and Y are preferably oxygen atoms or sulfur atoms, and more preferably oxygen atoms.

[0039] R in general formula (I) 1 R 2 R7 and R 8 Alkyl groups having 1 to 6 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc.

[0040] R in general formula (I) 1 R 2 R 7 and R 8 Alkenes with 2 to 6 carbon atoms include, for example, vinyl, allyl, propenyl, isopropenyl, butenyl, isobutenyl, pentenyl, heptenyl, hexenyl, iso-3-hexenyl, cyclohexenyl, etc.

[0041] R in general formula (I) 1 R 2 R 7 and R 8 Aryl groups, for example, include phenyl, tolyl, xylyl, naphthyl, etc.

[0042] R in general formula (I) 1 R 2 R 7 and R 8 Aryl groups, for example, include benzyl, 2-phenylethyl, 2-naphthylethyl, diphenylmethyl, etc.

[0043] Of the above, R is preferred. 1 R 2 R 7 and R 8 Each is independently any one of an alkyl group having 1 to 6 carbon atoms and an alkenyl group having 2 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and even more preferably a methyl group.

[0044] R in general formula (I) 3 R 4 R 5 and R 6 Alkyl groups having 1 to 6 carbon atoms, alkenyl groups having 2 to 6 carbon atoms, aryl groups, and aralkyl groups can be used to illustrate the relationship with the above-mentioned R. 1 R 2 R 7 and R 8 Alkyl groups, alkenyl groups with 2 to 6 carbon atoms, aryl groups, and aralkyl groups are the same as those in the group.

[0045] Of the above, R is preferred. 3 R 4 R 5 and R 6Each of the following is independently selected from hydrogen atom, alkyl group having 1 to 3 carbon atoms, alkenyl group having 2 or 3 carbon atoms, and aryl group, more preferably hydrogen atom or methyl group, and even more preferably hydrogen atom. From the perspective of improving the oxygen absorption performance of compound Q, R is preferred. 3 and R 6 All are hydrogen atoms, preferably R 4 and R 5 Each is independently a hydrogen atom or a methyl group, or more preferably, a hydrogen atom.

[0046] In general formula (I), from the perspective of ease of operation of compound Q, the linking group J is preferably an aliphatic hydrocarbon group with 3 to 10 carbon atoms, and more preferably an aliphatic hydrocarbon group with 3 to 5 carbon atoms. The linking group J may optionally contain a styreneoxy group as a substituent, for example, 4-styreneoxy. Furthermore, the linking group J may optionally contain an olefinoxy group with 2 to 5 carbon atoms, such as an ethyleneoxy group with 2 to 5 carbon atoms. From the perspective of improving the oxygen absorption performance of compound Q, the optional substituents in the linking group J are preferably hydroxyl or (meth)acryloyloxy.

[0047] As a specific example of the linking group J, from the perspective of improving the oxygen absorption performance of compound Q, the linking group represented by the following general formula (J-1) is more preferred. Furthermore, the linking group in general formula (J-1) is... "" indicates the bond point with X or Y. [Chemical Formula 2] In the above general formula (J-1), R 9 Represents a hydrogen atom or a methyl group, preferably a hydrogen atom. R 10 The term refers to any one of hydroxyl, (meth)acryloyloxy, styryloxy, and olefinic groups having 2 to 5 carbon atoms, with hydroxyl and (meth)acryloyloxy being preferred. Alternatively, the olefinic group having 2 to 5 carbon atoms may be an ethyleneoxy group having 2 to 5 carbon atoms.

[0048] As a specific example of compound Q, from the perspective of oxygen absorption performance, it easily satisfies the aforementioned requirements and b. From the perspective of relevant physical properties, compounds represented by the following general formula (II) are preferred. [Chemical Formula 3] In general formula (II), R 9 R represents a hydrogen atom or a methyl group. 10 R represents any one of hydroxyl, (meth)acryloyloxy, styryloxy, and olefinic groups having 2 to 5 carbon atoms. 11 R 12 R13 and R 14 Each can independently represent any one of alkyl, alkenyl, aryl, and aralkyl groups having 1 to 6 carbon atoms.

[0049] R in general formula (II) 10 Preferably, it is hydroxyl or (meth)acryloyloxy. R 10 An olefinic group with 2 to 5 carbon atoms can be an ethyleneoxy group with 2 to 5 carbon atoms.

[0050] R in general formula (II) 11 R 12 R 13 and R 14 The preferred forms are respectively related to R in the above general formula (I). 1 R 2 R 7 and R 8 same.

[0051] The oxygen absorbent in this embodiment is particularly preferably a compound represented by the following formula (III) (hereinafter sometimes referred to as "compound S"). [Chemical Formula 3]

[0052] There is no particular limitation on the method for producing compound Q; it can be produced by using known methods or by combining known methods. As an example, compound S can be produced by reacting a compound such as epichlorohydrin, which can form a linking group J, with 3-methyl-2-buten-1-ol in the presence of a base such as potassium hydroxide. For optimal reaction conditions, stirring at a temperature of approximately 25–70°C for approximately 2–10 hours is preferred.

[0053] The oxygen absorbent content in the adhesive of this embodiment is preferably 0.01 to 30% by mass, more preferably 0.05 to 25% by mass, particularly preferably 0.1 to 20% by mass, even more preferably 0.5 to 15% by mass, and preferably 0.8 to 10% by mass. This effectively suppresses end yellowing. From the perspective of more effectively suppressing end yellowing, the lower limit of the oxygen absorbent content is preferably 1% by mass or more, more preferably 2% by mass or more, and particularly preferably 3% by mass or more. On the other hand, from the perspective of blister resistance, the upper limit of the oxygen absorbent content is preferably 8% by mass or less, more preferably 6% by mass or less, particularly preferably 4% by mass or less, and even more preferably 2% by mass or less.

[0054] The adhesive used in this embodiment is preferably a pressure-sensitive adhesive, but it is not limited to pressure-sensitive adhesives. The type of adhesive in this embodiment can be any of acrylic adhesives, polyester adhesives, polyurethane adhesives, rubber adhesives, silicone adhesives, etc. Furthermore, the adhesive can be any of emulsion type, solvent-based type, or solvent-free type, and can be any of crosslinked type or non-crosslinked type. Among these adhesives, acrylic adhesives with excellent pressure-sensitive adhesive properties and optical properties are preferred.

[0055] Acrylic adhesives can be cured by active energy rays, cured by inactive energy rays, crosslinked, or non-crosslinked, or can be a combination of these acrylic adhesives. Among them, acrylic adhesives that are cured by active energy rays are preferred from the perspective of easily obtaining excellent step followability and anti-foaming properties.

[0056] Regarding the adhesive of this embodiment, from the perspective of film-forming properties, the adhesive main agent preferably contains a (meth)acrylate polymer, and particularly preferably a crosslinked product containing a (meth)acrylate polymer. Furthermore, the adhesive of this embodiment also preferably contains the aforementioned adhesive main agent and an active energy ray curable component. The crosslinked product of the (meth)acrylate polymer is preferably a crosslinked product of the (meth)acrylate polymer and a crosslinking agent.

[0057] Specifically, the adhesive of this embodiment is preferably formed by crosslinking (preferably thermal crosslinking) of an adhesive composition (hereinafter sometimes referred to as "adhesive composition P") containing a (meth)acrylate polymer (A), a crosslinking agent (B), an oxygen absorber (C), and an active energy ray-curable component (D). Additionally, in this specification, (meth)acrylate refers to both acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, "polymer" also includes the concept of "copolymer".

[0058] (1) Each ingredient (1-1) (Meth)acrylate polymer (A) The (meth)acrylate polymer (A) preferably contains structural units derived from alkyl (meth)acrylates. This results in good pressure-sensitive adhesion. Furthermore, the alkyl (meth)acrylate does not contain the hard monomers described later.

[0059] From the perspective of pressure-sensitive adhesion, alkyl methacrylates with 1 to 20 carbon atoms in the alkyl group are preferred as (meth)acrylates. Examples of alkyl methacrylates with 1 to 20 carbon atoms in the alkyl group include methyl acrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate, n-decyl methacrylate, n-dodecyl methacrylate, myristyl methacrylate, palmitate methacrylate, and stearate methacrylate. These alkyl methacrylates can be used alone or in combination of two or more. Among the above, from the perspective of further improving pressure-sensitive adhesion, alkyl methacrylates with 1 to 14 carbon atoms in the alkyl group are preferred, alkyl methacrylates with 2 to 10 carbon atoms in the alkyl group are more preferred, and alkyl methacrylates with 3 to 8 carbon atoms in the alkyl group are particularly preferred. Specifically, methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate or isooctyl acrylate are preferred, n-butyl acrylate or 2-ethylhexyl acrylate are particularly preferred, and 2-ethylhexyl acrylate is even more preferred.

[0060] From the perspective of imparting pressure-sensitive adhesion, the (meth)acrylate polymer (A) preferably contains 30-99% by mass, more preferably 40-92% by mass, particularly preferably 50-86% by mass, and even more preferably 55-80% by mass of structural units derived from (meth)acrylate, wherein, preferably, it contains 60-75% by mass of structural units derived from (meth)acrylate. As a result, the adhesive readily meets the properties described later, and exhibits excellent anti-foaming properties and step-following characteristics.

[0061] The (meth)acrylate polymer (A) preferably has structural units derived from monomers containing reactive functional groups. Thus, the reactive functional groups from the monomers react with the crosslinking agent (B) to form a crosslinked structure (three-dimensional network structure), thereby obtaining an adhesive with the desired cohesive strength.

[0062] As monomers containing reactive groups, preferred examples include monomers with intramolecular hydroxyl groups (hydroxyl-containing monomers), monomers with intramolecular carboxyl groups (carboxyl-containing monomers), and monomers with intramolecular amino groups (amino-containing monomers). Among these monomers containing reactive groups, hydroxyl-containing monomers or carboxyl-containing monomers with excellent reactivity with crosslinking agent (B) are preferred.

[0063] Examples of hydroxyl-containing monomers include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 3-hydroxybutyl methacrylate, 4-hydroxybutyl methacrylate, and other hydroxyalkyl methacrylates. Among these, 2-hydroxyethyl methacrylate or 4-hydroxybutyl methacrylate is preferred from the perspective of reactivity with the crosslinking agent (B) and copolymerization with other monomers. These hydroxyl-containing monomers can be used alone or in combination of two or more.

[0064] Examples of carboxyl-containing monomers include olefinic unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among these, acrylic acid or methacrylic acid is preferred, with acrylic acid being particularly preferred, considering its reactivity with the crosslinking agent (B) and its copolymerization properties with other monomers. These carboxyl-containing monomers can be used alone or in combination of two or more.

[0065] From the perspective of cohesion, the content of structural units from monomers containing reactive functional groups in the (meth)acrylate polymer (A) is preferably 1 to 40% by mass, more preferably 3 to 34% by mass, particularly preferably 6 to 28% by mass, further preferably 9 to 24% by mass, and preferably 12 to 20% by mass.

[0066] The (meth)acrylate polymer (A) preferably contains structural units derived from a hard monomer having a glass transition temperature (Tg) of 70°C or higher as a homopolymer. Furthermore, the hard monomer does not include the aforementioned monomers containing reactive functional groups. By including the structural units derived from the hard monomer in the (meth)acrylate polymer (A), the cohesive strength of the resulting adhesive is improved, and excellent step-following properties and anti-foaming properties are easily obtained. In particular, when structural units of (meth)acrylate with 5 to 8 carbon atoms derived from alkyl groups are included, there is a tendency for the cohesive strength to decrease; therefore, it is preferable to include the structural units derived from the hard monomer. The glass transition temperature (Tg) of the aforementioned hard monomer as a homopolymer is preferably 75 to 200°C, particularly preferably 80 to 180°C, and even more preferably 90 to 150°C.

[0067] Examples of the aforementioned hard monomers include methyl methacrylate (Tg 105℃), isobornyl acrylate (Tg 94℃), isobornyl methacrylate (Tg 180℃), adamantyl acrylate (Tg 115℃), and adamantyl methacrylate (Tg 141℃). These hard monomers can be used alone or in combination of two or more.

[0068] Among the aforementioned hard monomers, from the perspective of preventing adverse effects on other properties such as pressure-sensitive adhesion or transparency and further enhancing the performance of the hard monomers, methyl methacrylate or isobornyl acrylate is preferred, and isobornyl acrylate, as a monomer having an alicyclic structure (containing alicyclic monomers), is particularly preferred.

[0069] When the (meth)acrylate polymer (A) contains the above-mentioned structural units derived from hard monomers, from the perspective of cohesion, step follow-through and anti-foaming properties, the content of structural units derived from hard monomers is preferably 1 to 30% by mass, more preferably 4 to 25% by mass, particularly preferably 8 to 20% by mass, and even more preferably 10 to 16% by mass.

[0070] The (meth)acrylate polymer (A) preferably contains structural units derived from monomers having nitrogen atoms within the molecule (nitrogen-containing monomers). In particular, when an alicyclic monomer, especially isobornyl acrylate, is used as the aforementioned hard monomer, it is preferable to contain structural units derived from nitrogen-containing monomers. By including structural units from nitrogen-containing monomers, a specific polarity can be imparted to the adhesive, resulting in superior adhesion.

[0071] As the aforementioned nitrogen-containing monomer, from the perspective of giving the (meth)acrylate polymer (A) a suitable rigidity, a monomer having a nitrogen-containing heterocycle is preferred. Furthermore, from the perspective of increasing the degree of freedom of the portion derived from the aforementioned nitrogen-containing monomer in the higher-order structure of the formed adhesive, this nitrogen-containing monomer preferably does not contain reactive unsaturated double bond groups other than the polymerizable group used to form the (meth)acrylate polymer (A).

[0072] Examples of monomers having nitrogen-containing heterocycles include N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acryloylpyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylaziridine, ethyl aziridine(meth)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimazole, N-vinylcarbazole, and N-vinylphthalimide. Among these, N-(meth)acryloylmorpholine is preferred for its superior adhesive properties, and N-acryloylmorpholine is particularly preferred. These monomers having nitrogen-containing heterocycles can be used alone or in combination of two or more.

[0073] When the (meth)acrylate polymer (A) contains structural units from nitrogen-containing monomers, from the perspective of better adhesion, the content of structural units from nitrogen-containing monomers is preferably 1 to 20% by mass, more preferably 2 to 16% by mass, particularly preferably 3 to 12% by mass, and even more preferably 4 to 8% by mass.

[0074] The (meth)acrylate polymer (A) may also contain structural units from other monomers as desired. As other monomers, monomers that do not contain reactive functional groups are preferred so as not to interfere with the function of monomers containing reactive groups. Examples of such other monomers include methoxyethyl methacrylate, ethoxyethyl methacrylate, alkoxyalkyl methacrylates, vinyl acetate, styrene, etc. These other monomers may be used alone or in combination of two or more.

[0075] (Meth)acrylate polymer (A) can be obtained by solution polymerization, solvent-free polymerization, or emulsion polymerization. Solution polymers obtained by solution polymerization are preferred. As a solution polymer, it is easier to obtain a high molecular weight polymer, and the resulting adhesive readily meets the physical properties described later, and also readily achieves superior step-following properties and anti-foaming properties.

[0076] The polymerization form of (meth)acrylate polymer (A) can be either a random copolymer or a block copolymer.

[0077] The weight-average molecular weight of the (meth)acrylate polymer (A) is preferably 100,000 to 3,000,000, more preferably 200,000 to 2,400,000, particularly preferably 300,000 to 1,800,000, further preferably 400,000 to 1,200,000, and most preferably 450,000 to 800,000. This allows the resulting adhesive to readily meet the physical properties described later, and also facilitates the acquisition of superior step-following properties and anti-foaming properties. Furthermore, the weight-average molecular weight in this specification is a value converted from standard polystyrene determined by gel permeation chromatography (GPC).

[0078] In addition, in the adhesive composition P, the (meth)acrylate polymer (A) can be used alone or in combination of two or more.

[0079] From the perspective of excellent film-forming properties and pressure-sensitive adhesion, the content of (meth)acrylate polymer (A) in the adhesive composition P of this embodiment is preferably 70 to 99.9% by mass, more preferably 75 to 99% by mass, particularly preferably 80 to 96% by mass, and from the perspective of excellent anti-foaming properties and step followability, it is even more preferably 82 to 94% by mass, wherein preferably 86 to 92% by mass.

[0080] (1-2) Crosslinking agent (B) The crosslinking agent (B) can crosslink the (meth)acrylate polymer (A) by heating the adhesive composition P, thereby forming a well-formed three-dimensional network crosslinked structure. Thus, an adhesive with a specified cohesive strength can be obtained.

[0081] As the aforementioned crosslinking agent (B), any crosslinking agent that reacts with the reactive functional groups (hydroxyl or carboxyl groups) of the (meth)acrylate polymer (A) can be used. Examples include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, and ammonium salt-based crosslinking agents. Here, when the (meth)acrylate polymer (A) contains structural units derived from hydroxyl-containing monomers, an isocyanate-based crosslinking agent with excellent reactivity with hydroxyl groups is preferably used as the crosslinking agent (B). Furthermore, one type of crosslinking agent (B) can be used alone, or two or more types can be used in combination.

[0082] Isocyanate-based crosslinking agents contain at least polyisocyanate compounds. Examples of polyisocyanate compounds include: aromatic polyisocyanates such as toluene diisocyanate (TDI), diphenylmethane diisocyanate, and phenylene diisocyanate (XDI); aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and biuret forms, isocyanurate forms, and adducts of these polyisocyanates as reactants with low-molecular-weight compounds containing active hydrogen, such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. From the perspective of reactivity with hydroxyl groups, trimethylolpropane-modified aromatic polyisocyanates are preferred, and trimethylolpropane-modified toluene diisocyanate or trimethylolpropane-modified phenylene diisocyanate are particularly preferred. From the perspective of seasoning, trimethylolpropane-modified toluene diisocyanate is particularly preferred.

[0083] The content of crosslinking agent (B) in the adhesive composition P is preferably 0.01 to 10 parts by weight relative to 100 parts by weight of (meth)acrylate polymer (A), more preferably 0.04 to 5 parts by weight, particularly preferably 0.08 to 1 part by weight, further preferably 0.1 to 0.6 parts by weight, and most preferably 0.12 to 0.3 parts by weight. This results in better cohesion, makes it easier for the resulting adhesive to meet the physical properties described later, and readily achieves excellent step follow-through and anti-foaming properties.

[0084] (1-3) Oxygen absorbent (C) The oxygen absorber (C) used in the adhesive composition P is the aforementioned oxygen absorber, and its specific components and content (mass %) in the adhesive are as described above. The amount of oxygen absorber (C) in the adhesive composition P relative to 100 parts by mass of the (meth)acrylate polymer (A) is preferably 0.01 to 30 parts by mass, more preferably 0.1 to 25 parts by mass, particularly preferably 0.5 to 20 parts by mass, further preferably 1 to 16 parts by mass, and most preferably 2 to 12 parts by mass. This more effectively suppresses end yellowing. On the other hand, from the perspective of anti-foaming properties, the upper limit of the above-mentioned amount of oxygen absorber (C) is preferably 9 parts by mass or less, more preferably 6 parts by mass or less, particularly preferably 4 parts by mass or less, and further preferably 2 parts by mass or less.

[0085] (1-4) Active energy ray curing component (D) By incorporating an active energy ray curable component (D) into the adhesive composition P, the resulting adhesive becomes an active energy ray curable adhesive. Based on the adhesive layer cured by active energy rays, excellent step follow-through and anti-bubbling properties can be easily obtained through post-bonding active energy ray curing.

[0086] The active energy ray curable component (D) is not particularly limited as long as it does not impair adhesion and is cured by irradiation with active energy rays. It can be any one of monomers, oligomers, or polymers, or a mixture thereof. Among them, polyfunctional acrylate monomers that are easy to obtain with superior step follow-through and anti-foaming properties are preferably listed.

[0087] Examples of multifunctional acrylate monomers include: 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, and hydroxypivalic acid neopentyl glycol di(meth)acrylate. Di(meth)acrylate, dicyclopentyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified di(meth)acrylate phosphate, di(acryloyloxyethyl)isocyanurate, allylated cyclohexyl di(meth)acrylate, ethoxylated bisphenol A diacrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene and other difunctional compounds; trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, etc. Trifunctional types include acrylates, pentaerythritol tri(meth)acrylates, propylene oxide-modified trimethylolpropane tri(meth)acrylates, tri(acryloyloxyethyl)isocyanurate, and ε-caprolactone-modified tri-(2-(meth)acryloyloxyethyl)isocyanurate; tetrafunctional types include diglycerol tetra(meth)acrylates and pentaerythritol tetra(meth)acrylates; pentafunctional types include propionic acid-modified dipentaerythritol penta(meth)acrylates; and hexafunctional types include dipentaerythritol hexa(meth)acrylates and caprolactone-modified dipentaerythritol hexa(meth)acrylates. Among the aforementioned multifunctional acrylate monomers, from the perspective of the resulting adhesive's step-following properties and anti-foaming properties, di(acryloyloxyethyl)isocyanurate, tri(acryloyloxyethyl)isocyanurate, and ε-caprolactone-modified tri-(2-(meth)acryloyloxyethyl)isocyanurate, which contain an isocyanurate structure within their molecules, are preferred. More preferably, multifunctional acrylate monomers with three or more functionalities and containing an isocyanurate structure within their molecules are preferred, and ε-caprolactone-modified tri-(2-(meth)acryloyloxyethyl)isocyanurate is particularly preferred. These multifunctional acrylate monomers can be used alone or in combination of two or more. Furthermore, from the perspective of the resulting adhesive easily exhibiting the desired viscoelasticity, the molecular weight of the multifunctional acrylate monomer is preferably less than 20,000, more preferably less than 10,000, and particularly preferably less than 5,000. Furthermore, from the perspective of compatibility with (meth)acrylate polymer (A) and the ease with which the resulting adhesive satisfies the physical properties described later, a molecular weight of less than 1000 is preferred.

[0088] When the adhesive composition P contains an active energy-curing component (D), the content of the active energy-curing component (D) relative to 100 parts by weight of the (meth)acrylate polymer (A) is preferably 0.1 to 40 parts by weight, more preferably 1 to 30 parts by weight, particularly preferably 2 to 20 parts by weight, further preferably 3 to 15 parts by weight, and most preferably 4 to 10 parts by weight. As a result, the adhesive readily meets the physical properties described later and readily achieves superior step-following properties and anti-foaming properties.

[0089] (1-5) Photopolymerization initiator (E) When the adhesive composition P contains an active energy ray curable component (D) and uses ultraviolet light as the active energy ray, it is preferable that the adhesive composition P contains a photopolymerization initiator (E). This allows for efficient curing of the active energy ray curable component (D) and reduces polymerization curing time and the amount of ultraviolet light irradiation.

[0090] Examples of photopolymerization initiators (E) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 4-(2-hydroxyethoxy) These photopolymerization initiators include 2-(hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzoyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, oligomeric [2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]acetone], 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, etc. These photopolymerization initiators (E) can be used alone or in combination of two or more.

[0091] Among the above-mentioned photopolymerization initiators (E), from the perspective of easily obtaining better step follow-through and anti-foaming properties, phosphine-based photopolymerization initiators such as 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, or mixtures of 1-hydroxycyclohexylphenyl ketone and diphenyl ketone, are preferred, with 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide being particularly preferred.

[0092] The content of photopolymerization initiator (E) in the adhesive composition P is preferably 1 to 30 parts by mass relative to 100 parts by mass of the active energy ray curable component (D), particularly preferably 5 to 22 parts by mass, and even more preferably 8 to 16 parts by mass. As a result, the adhesive readily meets the physical properties described later, and easily achieves superior step follow-through and anti-foaming properties.

[0093] (1-6) Silane coupling agent (F) The adhesive composition P preferably further contains a silane coupling agent (F). This improves the adhesion between the adhesive and a glass component if the adherend has such a component. Furthermore, even if the adherend is a plastic sheet, the adhesion between the adhesive and the plastic sheet is improved. Consequently, the resulting adhesive readily meets the physical properties described later and easily achieves superior step follow-through and anti-foaming properties.

[0094] As a silane coupling agent (F), an organosilicon compound having good compatibility with (meth)acrylate polymers (A) and being transparent, and having at least one alkoxysilyl group in the molecule, is preferred.

[0095] Examples of silane coupling agents (F) include: vinyltrimethoxysilane, vinyltriethoxysilane, methacryloyloxypropyltrimethoxysilane, and other silicon compounds containing polymerizable unsaturated groups; 3-glycidyl etheroxypropyltrimethoxysilane, 3-glycidyl etheroxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and other silicon compounds with epoxy structures; 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, etc. Silicate coupling agents (F) include mercapto-containing silicon compounds such as methyldimethoxymethylsilane; amino-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane; condensates of 3-chloropropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, or at least one thereof with alkyl-containing silicon compounds such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane. These silane coupling agents (F) can be used alone or in combination of two or more.

[0096] The content of silane coupling agent (F) in the adhesive composition P is preferably 0.01 to 10 parts by weight relative to 100 parts by weight of (meth)acrylate polymer (A), more preferably 0.04 to 5 parts by weight, particularly preferably 0.08 to 1 part by weight, further preferably 0.12 to 0.7 parts by weight, and most preferably 0.15 to 0.4 parts by weight. As a result, the adhesive exhibits excellent adhesion, and its step-following and anti-foaming properties are even better. Furthermore, the resulting adhesive readily meets the physical properties described later.

[0097] (1-7) Various additives The adhesive composition P may also contain, as required, various additives commonly used in acrylic adhesives, such as ultraviolet absorbers, light stabilizers, antistatic agents, tackifiers, colorants, infrared absorbers, rust inhibitors, antioxidants, light stabilizers, softeners, fillers, refractive index modifiers, etc.

[0098] (2) Manufacturing of adhesive compositions The adhesive composition P can be manufactured by: manufacturing a (meth)acrylate polymer (A), mixing the obtained (meth)acrylate polymer (A), a crosslinking agent (B) and an oxygen absorber (C), and adding, as needed, an active energy ray curable component (D), a photopolymerization initiator (E), a silane coupling agent (F), additives, etc.

[0099] (Meth)acrylate polymer (A) can be manufactured by polymerizing a mixture of monomers constituting the polymer using conventional free radical polymerization. The polymerization of (meth)acrylate polymer (A) is preferably carried out using a polymerization initiator and via solution polymerization, depending on the desired method. However, the invention is not limited thereto, and polymerization can also be performed under solvent-free conditions.

[0100] Examples of polymerization solvents include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone; two or more may be used simultaneously. Examples of polymerization initiators include azo compounds and organic peroxides; two or more may be used simultaneously. Furthermore, by incorporating chain transfer agents such as 2-mercaptoethanol during the polymerization process, the weight-average molecular weight of the resulting polymer can be adjusted.

[0101] After obtaining (meth)acrylate polymer (A), a crosslinking agent (B), an oxygen absorber (C), and, according to the desired active energy radiation curing component (D), a photopolymerization initiator (E), a silane coupling agent (F), additives, a diluent, etc., are added to the solution of (meth)acrylate polymer (A) and thoroughly mixed to obtain a solvent-diluted adhesive composition P (coating solution). Furthermore, if any of the above components are used as solid substances, or if precipitation occurs when any of the above components are mixed with other components in an undiluted state, the component can be pre-dissolved or diluted in a diluent before being mixed with the other components.

[0102] For example, the following can be used as diluents: aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and 1,2-dichloroethane; alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; and cellosolve solvents such as ethyl cellosolve.

[0103] The concentration and viscosity of the coating solution prepared in this way are not particularly limited as long as they are within a coatable range, and can be appropriately selected according to the situation. For example, the adhesive composition P can be diluted to a concentration of 10 to 60% by mass. Furthermore, the addition of a diluent is not necessary when obtaining the coating solution; as long as the adhesive composition P has a coatable viscosity, a diluent may not be added. In this case, the adhesive composition P becomes a coating solution in which the polymerization solvent of (meth)acrylate polymer (A) is directly used as the diluent.

[0104] (3) Manufacturing of adhesives After applying the above adhesive composition P to the desired object, crosslinking is performed to obtain the adhesive (adhesive layer).

[0105] Crosslinking of the adhesive composition P can be achieved by heat treatment. The drying process following coating of the adhesive composition P can also serve as the heat treatment. The heating temperature for the heat treatment is preferably 50 to 150°C, particularly preferably 70 to 120°C. Furthermore, the heating time is preferably 10 seconds to 10 minutes, particularly preferably 50 seconds to 2 minutes.

[0106] After heat treatment, a curing period of approximately 1 to 2 weeks can be set at room temperature (e.g., 23°C, 50%RH) as needed. If this curing period is required, an adhesive will form after the curing period; if no curing period is required, an adhesive will form after the heat treatment is completed. Additionally, in this specification, "relative humidity α%" is sometimes expressed as "α%RH (RH; Relative humidity)".

[0107] Through the above-mentioned heat treatment (and aging), a cross-linked product of (meth)acrylate polymer (A) is formed by cross-linking with cross-linking agent (B).

[0108] (4) Physical properties (gel fraction) The gel fraction of the adhesive in this embodiment is preferably 20-100%, more preferably 25-90%, particularly preferably 30-80%, further preferably 35-80%, and most preferably 41-70%. Therefore, when applied to the substrate, good pressure-sensitive adhesion, good anti-foaming properties, and good step-following properties are easily obtained. Furthermore, the method for determining the gel fraction in this specification is shown in the experimental examples described later.

[0109] When the adhesive in this embodiment is an active energy ray curable adhesive, the gel fraction of the adhesive after active energy ray curing is preferably 30-100%, more preferably 40-90%, particularly preferably 45-80%, further preferably 50-70%, and most preferably 55-64%. Therefore, the adhesion to the adhered objects is easily improved, and good anti-foaming properties and step-following properties are readily obtained.

[0110] Here, when the adhesive of this embodiment contains a crosslinking agent (B), a curing period is preferably set. However, 7 days after the adhesive of this embodiment forms a coating layer, the gel fraction (gel fraction G1) of the adhesive is preferably 20 to 100%, more preferably 25 to 90%, particularly preferably 30 to 80%, further preferably 35 to 70%, and preferably 41 to 60%.

[0111] Furthermore, 14 days after the adhesive of this embodiment forms the coating layer, the gel fraction (gel fraction G2) of the adhesive is preferably 20 to 100%, more preferably 25 to 90%, particularly preferably 30 to 80%, further preferably 35 to 70%, and preferably 42 to 60%.

[0112] Furthermore, the difference (G2-G1; percentage points) obtained by subtracting the gel fraction G1 (%) from the gel fraction G2 (%) is preferably 15 percentage points or less, more preferably 10 percentage points or less, more preferably 7 percentage points or less, particularly preferably 4 percentage points or less, more preferably 2 percentage points or less, and most preferably 1 percentage point or less. Thus, by keeping the difference between the gel fraction G2 and the gel fraction G1 small, excellent aging can be achieved.

[0113] When the adhesive of this embodiment is an active energy ray curable adhesive, the gel fraction (gel fraction G1c) of the adhesive that has been cured by active energy ray 7 days after the adhesive forms the coating layer is preferably 30 to 100%, more preferably 40 to 90%, particularly preferably 45 to 80%, further preferably 50 to 70%, and preferably 55 to 64%.

[0114] Furthermore, the gel fraction (gel fraction G2c) of the adhesive that has been cured by active energy rays 14 days after the formation of the above-mentioned adhesive coating is preferably 30 to 100%, more preferably 40 to 90%, particularly preferably 45 to 80%, further preferably 50 to 70%, and preferably 55 to 64%.

[0115] [Adhesive sheet] The adhesive sheet of this embodiment has an adhesive layer for bonding two components together. At least one of the aforementioned components is an optical component. The specific structure of the adhesive sheet and the optical component are described below.

[0116] The adhesive layer in the adhesive sheet of this embodiment is composed of the adhesive of the aforementioned embodiment.

[0117] From the perspectives of adhesion, step followability, and anti-bubbling properties, the thickness of the adhesive layer of the adhesive sheet in this embodiment (the value obtained by measurement according to JIS (Japanese Industrial Standards) K7130) is preferably 1 to 1000 μm, more preferably 10 to 600 μm, particularly preferably 20 to 300 μm, and preferably 30 to 150 μm, further preferably 40 to 100 μm, and most preferably 45 to 70 μm, from the perspective that end yellowing is less of a problem.

[0118] (1)Physical properties (1-1) Energy storage modulus G' In this embodiment, the storage modulus G' of the adhesive forming the bonded adhesive layer at 23°C is preferably 0.001~10 MPa, more preferably 0.010~1 MPa, more preferably 0.020~0.500 MPa, particularly preferably 0.030~0.100 MPa, and even more preferably 0.035~0.060 MPa. Therefore, the adhesive strength of the bonded component is easily improved, and good anti-bubbling and step-following properties are readily obtained. Furthermore, the method for determining the storage modulus G' in this specification is shown in the experimental examples described later.

[0119] In this embodiment, the storage modulus G' of the adhesive forming the bonded adhesive layer at 80°C is preferably 0.001~2 MPa, more preferably 0.003~1 MPa, more preferably 0.006~0.100 MPa, particularly preferably 0.010~0.050 MPa, and even more preferably 0.015~0.023 MPa. Therefore, the bonding strength at high temperatures after bonding the components is readily improved, and good anti-bubbling properties and step-following properties are easily obtained.

[0120] Here, the term "adhesive layer after bonding" in this specification refers to an adhesive layer in the same state as the adhesive layer of the adhesive sheet when the adhesive layer is non-reactive energy ray curable, and to an adhesive layer cured by active energy ray after bonding by irradiation with active energy rays when the adhesive layer is active energy ray curable.

[0121] (1-2) Adhesion In this embodiment, the adhesion strength of the bonded adhesive layer to soda-lime glass after bonding is preferably 1~100 N / 25 mm, more preferably 6~70 N / 25 mm, particularly preferably 12~60 N / 25 mm, even more preferably 18~50 N / 25 mm, and most preferably 24~44 N / 25 mm. This results in excellent step follow-through and anti-bubbling properties. The aforementioned adhesion strength is essentially the adhesion strength measured according to the 180-degree peel method of JIS Z0237:2009, and the specific test method is shown in the test examples described later.

[0122] (1-3) Total transmittance In this embodiment, the total light transmittance of the adhesive layer after bonding is preferably 80% or more, more preferably 90% or more, particularly preferably 95% or more, and even more preferably 99% or more. This results in very high transparency, suitable for optical applications (for displays). There is no particular upper limit to the total light transmittance; it can be 100%, or a value slightly exceeding 100% due to measurement requirements. The total light transmittance in this specification is a value measured according to JIS K7361-1:1997, and the specific test method is shown in the test examples described later.

[0123] (1-4) Haze value In this embodiment, the haze value of the adhesive layer after bonding is preferably 2% or less, and particularly preferably 1% or less. This results in very high transparency, suitable for optical applications (for displays). There is no particular limitation on the lower limit of the haze value; it can be 0%. The haze value in this specification is a value measured according to JIS K7136:2000, and the specific test method is shown in the test examples described later.

[0124] (1-5) Segment Follow-up Rate In this embodiment, the step follow rate (%) of the adhesive layer after bonding, as shown in the following formula, is preferably 20% or more, particularly preferably 30% or more, and even more preferably 40% or more. This ensures excellent step follow performance under high temperature and high humidity conditions, and also ensures excellent step follow performance in the initial stage (during bonding). Furthermore, there is no particular upper limit to the step follow rate; it is generally preferred to be 80% or less, and particularly preferably 70% or less. Step follow-through rate (%) = {(Step height (μm) that remains in landfill condition without bubbles, buoyancy, peeling, etc. after the specified durability test) / (Thickness of adhesive layer)} × 100 In addition, the experimental method for the step difference following rate is shown in the experimental example described later.

[0125] (2) Specific composition of adhesive sheet Figure 1 The specific structure of the adhesive sheet as an example of this embodiment is shown. like Figure 1 As shown, in one embodiment, the adhesive sheet 1 comprises two release sheets (release sheets 12a and 12b) and an adhesive layer 11, wherein the adhesive layer 11 is sandwiched between the two release sheets (release sheets 12a and 12b) in such a manner that it contacts the release surfaces of the two release sheets (release sheets 12a and 12b). Furthermore, in this specification, the release surface of a release sheet refers to the surface of the release sheet that exhibits release properties, including either a surface that has undergone a release treatment or a surface that, although not subjected to a release treatment, still exhibits release properties.

[0126] The adhesive layer 11 is composed of the adhesive of the aforementioned embodiment. Release tabs 12a and 12b protect the adhesive layer until the adhesive sheet is used, at which point the adhesive layer is peeled off. In the adhesive sheet 1 of this embodiment, one or both of release tabs 12a and 12b are not necessary.

[0127] As release sheets 12a and 12b, for example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate film, ionomer resin film, ethylene-(meth)acrylate copolymer film, ethylene-(meth)acrylate polymer film, polystyrene film, polycarbonate film, polyimide film, fluoropolymer film, etc. Furthermore, cross-linked films of these films can also be used. Further, laminated films of these films can also be used. In addition, from the perspective of SDGs (Sustainable Development Goals), materials with high biomass, materials that can be recycled or reused, and materials that have already been recycled or reused can be used as the materials constituting the release sheets.

[0128] It is preferable to perform a peeling treatment on the peeling surfaces (especially the surfaces in contact with the adhesive layer 11) of the release sheets 12a and 12b. Examples of release agents used in the peeling treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents.

[0129] There are no particular limitations on the thickness of the release strips 12a and 12b, which are usually around 20~150μm.

[0130] From an operational perspective, among the two peeling sheets (peeling sheet 12a and peeling sheet 12b), it is preferable to set one peeling sheet as a heavy-peeling peeling sheet with high peeling force and the other peeling sheet as a light-peeling peeling sheet with low peeling force.

[0131] (3) Manufacturing of adhesive sheets As an example of manufacturing adhesive sheet 1, a coating liquid of the adhesive composition P is applied to the release surface of a release sheet 12a (or release sheet 12b), and after heat treatment to thermally crosslink the adhesive composition P and form a coating layer, the release surface of another release sheet 12b (or release sheet 12a) is laminated onto this coating layer. If a curing period is required, a curing period is provided, thereby making the coating layer an adhesive layer 11; if a curing period is not required, the coating layer directly becomes the adhesive layer 11. Through the above processes, adhesive sheet 1 is obtained. The heat treatment and curing conditions are as described above.

[0132] Methods for applying the coating liquid as a coating adhesive composition P include, for example, rod coating, knife coating, roller coating, blade coating, die coating, gravure coating, etc.

[0133] (4) Applications The adhesive sheet in this embodiment is used to bond two components together, at least one of which is an optical component.

[0134] As optical components, in addition to the components constituting the display body (display body components) described later, examples include components constituting solar cells, moving bodies (vehicles, ships, aircraft, etc.), and components constituting buildings (windows, exterior materials, interior materials, etc.), which are usually components made of light-transmitting plastic sheets, plastic films, glass sheets, glass films, etc., or components containing the above-mentioned components.

[0135] The other component of the two components can be an optical component, or a component made of an opaque or translucent material. For example, it can be a component made of metal, ceramic, colored plastic, colored glass, graphite, paper, wood, stone, mortar, plaster, etc., or a component containing the above components.

[0136] [Optical Components] An optical component according to one embodiment of the present invention is formed by bonding at least two components together using an adhesive layer, at least one of which is an optical component. The adhesive layer is formed by the adhesive of the aforementioned embodiment or by the adhesive layer of the adhesive sheet of the aforementioned embodiment.

[0137] The thickness of the adhesive layer in this embodiment is the same as the thickness of the adhesive layer in the adhesive sheet of the aforementioned embodiment. Furthermore, the optical components are as described in the aforementioned embodiments.

[0138] In manufacturing the optical components of this embodiment, as an example, after applying the aforementioned adhesive coating liquid to a component to form an adhesive layer, other components are bonded to the adhesive layer. As another example, after attaching the aforementioned adhesive sheet adhesive layer to a component, other components are bonded to the adhesive layer.

[0139] Here, when the adhesive layer is curable by active energy rays, it is preferable to cure the adhesive layer by irradiating it with active energy rays through any component (the component through which the active energy rays pass) after the above-mentioned bonding.

[0140] Reactive energy rays refer to rays containing energy quanta within electromagnetic waves or charged particle beams; specifically, examples include ultraviolet light and electron beams. Among reactive energy rays, ultraviolet light, which is particularly easy to manipulate, is preferred.

[0141] Ultraviolet (UV) irradiation can be achieved using high-pressure mercury lamps, Heraeus H lamps, xenon lamps, etc. The preferred UV irradiation intensity is 50–1000 mW / cm². 2 Approximately. Furthermore, the optimal light intensity is 50~10000 mJ / cm². 2 More preferably 80~5000 mJ / cm 2 The preferred value is 300~2000 mJ / cm³. 2 On the other hand, electron beam irradiation can be performed using an electron beam accelerator or the like, and the preferred irradiation dose is around 10 to 1000 krad.

[0142] [Display Body] One embodiment of the present invention provides a display body comprising a display body component, another display body component, and an adhesive layer for bonding the one display body component and the other display body component together. This adhesive layer is formed from the adhesive layer of the adhesive sheet of the aforementioned embodiment.

[0143] At least one of the aforementioned display body components and another display body component may have a step difference on at least one side of the surface bonded by the aforementioned adhesive layer.

[0144] Both of the aforementioned display components can be rigid sheets. When two rigid sheets are bonded together, since these rigid sheets are hard and do not bend, by pressing the two rigid sheets vertically with the adhesive layer already attached to one rigid sheet, each rigid sheet is sealed to the adhesive layer, thereby bonding the two rigid sheets together.

[0145] The display body of one embodiment of the present invention will be described with reference to the accompanying drawings. like Figure 2 As shown, the display body 2 of this embodiment is constructed by having a first display body component 21 (one display body component), a second display body component 22 (another display body component) and an adhesive layer 11 located between the first display body component 21 and the second display body component 22 and bonding the first display body component 21 and the second display body component 22 together.

[0146] At least one of the first display body component 21 and the second display body component 22 may have a step at least on the side of the surface that is bonded by the adhesive layer 11. Figure 2 In the embodiment shown, the surface of the first display body component 21 on the adhesive layer 11 side has a step caused by the printing layer 3, etc.

[0147] The adhesive layer 11 in the display body 2 is either the adhesive layer 11 (non-active energy ray curable) of the aforementioned adhesive sheet 1 itself, or the adhesive layer 11 (active energy ray curable) of the aforementioned adhesive sheet 1 is cured by irradiation with active energy rays.

[0148] Display devices 2 can include, for example, liquid crystal displays (LCDs), light-emitting diode (LED) displays, organic electroluminescent (OLED) displays, electronic paper, and touch panels. Furthermore, LED displays also include those using miniature LEDs or micro LEDs.

[0149] The first display component 21, in addition to glass plates and plastic plates, is preferably a protective panel composed of a laminate including glass plates and plastic plates. In this case, the printed layer 3 is generally formed in a frame shape on the adhesive layer 11 side of the first display component 21.

[0150] There are no particular limitations on the glass plates mentioned above; examples include chemically tempered glass, alkali-free glass, quartz glass, soda-lime glass, barium / strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, and barium borosilicate glass. The thickness of the glass plate is not particularly limited, but is typically 0.1–5 mm, preferably 0.2–2 mm.

[0151] There are no particular limitations on the plastic sheet used, and examples include acrylic sheets and polycarbonate sheets. The thickness of the plastic sheet is not particularly limited, but is typically 0.2 to 5 mm, preferably 0.4 to 3 mm.

[0152] In addition, various functional layers (transparent conductive film, metal layer, silicon dioxide layer, hard coating, anti-glare layer, etc.) can be applied to one or both sides of the aforementioned glass or plastic plate, and optical components can also be stacked. Furthermore, the transparent conductive film and metal layer can be patterned.

[0153] The second display component 22 is preferably an optical component, a display module (e.g., a liquid crystal (LCD) module, a light-emitting diode (LED) module, an organic electroluminescent (OLED) module, an optical component that is part of the display module, or a laminate containing the display module that should be attached to the first display component 21.

[0154] Examples of such optical components include anti-scattering films, polarizers, polarizers, retardation plates, viewing angle compensation films, brightness enhancement films, contrast enhancement films, liquid crystal polymer films, diffusion films, semi-transparent reflective films, and transparent conductive films. As a transparent conductive film, an ITO-PET film with an indium tin oxide (ITO) layer formed on one side of a polyethylene terephthalate (PET) film is preferably cited as an example.

[0155] The material constituting the printed layer 3 is not particularly limited, and known materials used for printing can be used. The thickness of the printed layer 3, i.e., the height of the step, is preferably 0.5 to 50 μm, more preferably 1 to 30 μm, and particularly preferably 3 to 20 μm. By keeping the thickness of the printed layer 3 within the above range, the step following ability provided by the adhesive layer 11 can be effectively utilized, and the opacity intended for the printed layer 3 can be sufficiently ensured. In addition, the printed layer 3 is generally formed in a frame shape on the adhesive layer 11 side of the display component.

[0156] As an example, when manufacturing the display body 2, a peeling sheet 12a of the adhesive sheet 1 is peeled off, and the exposed adhesive layer 11 of the adhesive sheet 1 is attached to the side of the first display body component 21 where the printed layer 3 is present.

[0157] Next, another release sheet 12b is peeled off from the adhesive layer 11 of the self-adhesive sheet 1, and the exposed adhesive layer 11 of the self-adhesive sheet 1 is bonded to the second display body component 22 to obtain the display body. In addition, as another example, the bonding order of the first display body component 21 and the second display body component 22 can be interchanged.

[0158] Here, when the adhesive layer 11 is curable by active energy rays (containing active energy ray curable component (D)), it is preferable that after the first display body component 21 is bonded to the laminate of the adhesive layer 11 and the second display body component 22, the adhesive layer 11 is irradiated with active energy rays through the first display body component 21 and / or the second display body component 22 to cure the adhesive layer 11.

[0159] In the display body 2, since the adhesive constituting the adhesive layer 11 contains the aforementioned oxygen absorber, even when exposed to high temperature for a long time (for example, exposed to an atmosphere at 140°C for 100 hours), yellowing of the adhesive layer 11 at the end of the display body 2 can be suppressed.

[0160] The embodiments described above are provided for ease of understanding of the present invention and are not intended to limit the invention. Therefore, the elements disclosed in the above embodiments are intended to include all design changes or equivalents that fall within the scope of the present invention.

[0161] For example, either or both of the release tabs 12a and 12b in the adhesive sheet 1 can be omitted. Alternatively, the required optical components can be laminated to replace the release tabs 12a and / or 12b. Furthermore, the first display body component 21 may not have a step. Further, not only may the first display body component 21 have a step on the adhesive layer 11 side, but the second display body component 22 may also have a step on the adhesive layer 11 side.

[0162] Furthermore, in this specification, when referred to as "X~Y" (where X and Y are arbitrary numbers), unless otherwise specified, it includes the meaning of "X or more and Y or less" as well as "preferably greater than X" or "preferably less than Y". Similarly, when referred to as "X or more" (where X is any number), unless otherwise specified, it includes the meaning of "preferably greater than X", and when referred to as "Y or less" (where Y is any number), unless otherwise specified, it includes the meaning of "preferably less than Y". Example

[0163] The present invention will be further described in detail below through examples, etc., however, the scope of the present invention is not limited to these examples, etc.

[0164] [Example 1] 1. Preparation of (meth)acrylate polymers (Meth)acrylate polymer (A) was prepared by solution polymerization of 65 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of isobornyl acrylate, 5 parts by mass of N-acryloylmorpholine, and 15 parts by mass of 2-hydroxyethyl acrylate. The molecular weight of (meth)acrylate polymer (A) was determined by the method described later, and the weight-average molecular weight (Mw) was 500,000.

[0165] 2. Preparation of adhesive compositions The following are used: 100 parts by mass (solid content conversion value; the same below) of the (meth)acrylate polymer (A) obtained in step 1 above; 0.15 parts by mass of an isocyanate-based crosslinking agent (B1; manufactured by Mitsui Chemicals, Inc., product name "TAKENATE D-101E", isocyanate type: TDI) as a crosslinking agent (B); 1 part by mass of the compound represented by the following formula (III) as an oxygen absorber (C) (manufactured by KURARAY CO., LTD., product name "Diprenyl GlycerinEther (DPNG)"); and 6.9 parts by mass of ε-caprolactone-modified tri-(2-acryloyloxyethyl) isocyanurate (manufactured by SHIN-NAKAMURA CHEMICAL CO, LTD., product name "NK ESTER") as an active energy ray curing component (D). A-9300-1CL”), 0.69 parts by weight of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide as photopolymerization initiator (E) and 0.25 parts by weight of 3-glycidyl etheroxypropyltrimethoxysilane as silane coupling agent (F) are mixed, stirred thoroughly and diluted with methyl ethyl ketone to obtain a coating solution of adhesive composition. [Chemical Formula 4]

[0166] Table 1 shows the proportions (converted to solids content) of the adhesive composition when (meth)acrylate polymer (A) is set at 100 parts by weight. Details of the abbreviations, etc., listed in Table 1 are as follows. [(Meth)acrylate polymer (A)] 2EHA: 2-Ethylhexyl acrylate IBXA: Isoborneol Acrylate ACMO: N-Acryloylmorpholine HEA: 2-Hydroxyethyl acrylate [Crosslinking agent (B)] B1: Isocyanate-based crosslinking agent, manufactured by Mitsui Chemicals, Inc., product name "TAKENATE D-101E", isocyanate type = TDI B2: Isocyanate-based crosslinking agent, manufactured by Soken Chemical & Engineering Co., Ltd., product name "TD-75", isocyanate type = XDI

[0167] 3. Manufacturing of adhesive sheets Using a coating machine, the coating solution of the adhesive composition obtained in step 2 above is applied to the peeling treatment surface of a heavy-peel release sheet R1, which has undergone peeling treatment on one side of the polyethylene terephthalate film using a silicone-based release agent. Then, a coating layer is formed by heat treatment at 90°C for 1 minute. Next, the coating layer on the release sheet R1 is bonded to a light-peel release sheet R2 with the peeling treatment surface of R2 in contact with the coating layer, and cured for 7 days at 23°C and 50% RH. This produces an adhesive sheet with an adhesive layer of 50 μm thickness, i.e., an adhesive sheet composed of release sheet R1 / adhesive layer (thickness: 50 μm) / release sheet R2, where the light-peel release sheet R2 has undergone peeling treatment on one side of the polyethylene terephthalate film using a silicone-based release agent.

[0168] The thickness of the adhesive layer was measured according to JIS K7130 using a constant pressure thickness gauge (manufactured by TECLOCK, product name "PG-02"). Furthermore, regarding the peel force of the release liner R1 and release liner R2 in the obtained adhesive sheet, it was confirmed that the peel force of release liner R1 is greater than that of release liner R2.

[0169] [Examples 2-4, Comparative Example 1] Except for changing the type of crosslinking agent (B) and the amount of oxygen absorber (C) as shown in Table 1, the adhesive sheet was manufactured in the same manner as in Example 1.

[0170] Here, the aforementioned weight-average molecular weight (Mw) is the weight-average molecular weight converted from polystyrene determined using gel permeation chromatography (GPC) under the following conditions (GPC determination). <Measurement Conditions> • Measuring apparatus: Manufactured by TOSOH CORPORATION, HLC-8320 • GPC column (passes through in the following order): Manufactured by TOSOH CORPORATION TSK gel superH-H TSK gel superHM-H TSK gel superH2000 • Determination solvent: tetrahydrofuran • Measurement temperature: 40℃

[0171] [Experimental Example 1] (Determination of gel fraction / Aging evaluation) An adhesive layer with a thickness of 250 μm was prepared by stacking adhesive layers of the adhesive sheets manufactured in the multilayer examples and comparative examples (7 days after the formation of the coating layer). This adhesive layer (thickness: 250 μm) was cut into 70 mm × 150 mm pieces, wrapped in a polyester mesh (mesh size 200), and its mass was measured using a precision balance. The mass of the mesh alone was subtracted to calculate the mass of the adhesive only. This mass is designated as M1.

[0172] Next, the adhesive wrapped in the aforementioned polyester mesh was impregnated in ethyl acetate at room temperature (23°C) for 24 hours. Then, the adhesive was removed and air-dried at 23°C and 50% RH for 24 hours, followed by further drying in an oven at 80°C for 12 hours. After drying, its mass was measured using a precision balance, and the mass of the mesh alone was subtracted to calculate the mass of the adhesive alone. This mass is designated as M2. The gel fraction (%; G1) is expressed as (M2 / M1) × 100. The results are shown in Table 2.

[0173] Furthermore, an adhesive layer (thickness: 250 μm) prepared in the same manner as described above was irradiated with active energy rays (ultraviolet; UV) to cure the adhesive layer. The gel fraction (%; G1c) of the adhesive layer after curing with active energy rays was measured in the same manner as described above. The results are shown in Table 2. The irradiation conditions of the active energy rays are shown below.

[0174] <Conditions for Irradiation by Active Energy Rays> • Use a high-pressure mercury lamp Illuminance: 200mW / cm² 2 Light intensity: 1000 mJ / cm 2 • The UV illuminance / photometer used is the "UVPF-A1" manufactured by EYE GRAPHICS COMPANY.

[0175] On the other hand, the adhesive sheets manufactured in the examples and comparative examples were further cured for 7 days to obtain an adhesive layer 14 days after the formation of the coating layer. The gel fraction (%; G2) of this adhesive layer was measured in the same manner as described above. Furthermore, the adhesive layer 14 days after the formation of the coating layer was irradiated with active energy rays (ultraviolet; UV) in the same manner as described above to cure the adhesive layer. The gel fraction (%; G2c) of the adhesive layer cured by active energy rays was measured in the same manner as described above. The respective results are shown in Table 2.

[0176] Furthermore, the difference (G2-G1; percentage points) obtained by subtracting the gel fraction G1 (%) from the gel fraction G2 (%) was calculated, and aging was evaluated according to the following criteria. The results are shown in Table 2. The difference between …(G2-G1) is less than 5 percentage points. The difference between ×…(G2-G1) is more than 5 percentage points.

[0177] [Experimental Example 2] (Determination of Storage Modulus G') An adhesive layer with a thickness of 250 μm was prepared by stacking the adhesive layers of the adhesive sheets manufactured in the multilayer examples and comparative examples. This 250 μm adhesive layer was then irradiated with active energy rays (ultraviolet; UV) under the same conditions as in Test Example 1 to cure the adhesive layer. A cylinder with a diameter of 8 mm (height of 0.25 mm) was punched from the 250 μm adhesive layer after curing by active energy rays, and this cylinder was used as a sample.

[0178] For the above samples, according to JIS K7244-1, the dynamic viscoelasticity was determined using a viscoelasticity measuring apparatus (manufactured by Anton Paar, product name "MCR302") by torsional shear method under the following conditions, and the storage modulus G' (MPa) at 23°C and 80°C was observed. The results are shown in Table 2. Measurement frequency: 1Hz Measurement temperature range: 0℃~140℃ Heating rate: 4℃ / minute

[0179] [Experimental Example 3](b) (Determination / Evaluation of end yellowing) An adhesive layer with a thickness of 250 μm was prepared by laminating the adhesive layers of the adhesive sheets manufactured in the multilayer examples and comparative examples. Using this adhesive layer (thickness: 250 μm), two soda-lime glass plates (manufactured by Nippon Sheet Glass Co., Ltd., thickness: 1.1 mm, length 7.0 mm × width 7.0 mm) were bonded together to create a laminate (soda-lime glass plate / adhesive layer (250 μm) / soda-lime glass plate). During this bonding process, a high-pressure treatment was performed at 0.5 MPa and 50°C for 20 minutes using an autoclave manufactured by Kurihara Seisakusho Co., Ltd.

[0180] Next, the laminate was irradiated with active energy rays (ultraviolet; UV) under the same conditions as in Test Example 1 to cure the adhesive layer, and the laminate was used as a sample for testing.

[0181] For the obtained test samples, a simultaneous spectrophotometer (manufactured by NIPPON DENSHOKUINDUSTRIES Co., Ltd., product name "SQ2000") was used to measure the values ​​specified in CIE 1976L. a b The color b specified in the color system (color b) 1). Furthermore, since the soda-lime glass plate constituting the sample for measurement is colorless and transparent, the colorimetric b measured here... The color b of the adhesive layer (after curing) The results are shown in Table 2.

[0182] Next, the test samples were placed under a durability condition of immersion in an atmosphere at 140°C for 100 hours. The colorimetric values ​​(b) at the ends and center of the test samples after this durability condition were measured in the same manner as described above. (End point: chromaticity b) 2. Central section: Chromaticity b 3). The results are shown in Table 2. Here, the end of the sample for measurement refers to a circular area with a radius of 2 mm, the center of which is located 3 mm inward from the central end face of any side of the sample in the top view. Furthermore, the central part of the sample for measurement refers to a 10 mm square area with the top view center point of the sample as the same center point.

[0183] Calculate the above chromaticity b 2. Relative to the chromaticity b obtained above The ratio of 1 to (b) 2 / b 1) the absolute value, and the aforementioned chromaticity b 2 relative to chromaticity b The ratio of 3 (b) 2 / b 3) Absolute values. Based on the above measured and calculated values, the end yellowing was evaluated according to the following criteria. The results are shown in Table 2. <Benchmark 1> ◎…b 2 / b The absolute value of 1 is less than 2.5. 〇…b 2 / b The absolute value of 1 is greater than 2.5 and less than 4.5. ×…b 2 / b The absolute value of 1 is greater than 4.5. <Benchmark 2> ◎…b The absolute value of 2 is less than 1.0. 〇…b The absolute value of 2 is greater than 1.0 and less than 2.0. ×…b The absolute value of 2 is greater than 2.0. <Benchmark 3> ◎…b 2 / b The absolute value of 3 is less than 1.8. 〇…b 2 / b The absolute value of 3 is greater than 1.8 and less than 2.5. ×…b 2 / b The absolute value of 3 is greater than 2.5.

[0184] [Experimental Example 4] (Determination of Total Transmittance) The test sample was prepared in the same manner as in Test Example 3. Regarding this test sample, based on background measurement using a soda-lime glass plate, the total transmittance (%) was measured using a haze meter (manufactured by NIPPON DENSHOKU INDUSTRIES Co., Ltd., product name "NDH-5000") according to JIS K7361-1:1997. The results are shown in Table 2. Additionally, the total transmittance of the adhesive layer before curing with active energy rays was also measured, and the results were the same.

[0185] [Experimental Example 5] (Determination of Haze Value) The test sample was prepared in the same manner as in Test Example 3. For this test sample, based on background measurements using a soda-lime glass plate, the haze value (%) was measured using a haze meter (manufactured by NIPPON DENSHOKU INDUSTRIES Co., Ltd., product name "NDH-5000") according to JIS K7136:2000. The results are shown in Table 2. Additionally, the haze value of the adhesive layer before curing with active energy rays was also measured, and the results were the same.

[0186] [Experimental Example 6] (Determination of Adhesion) Peel off release sheet R2 from the adhesive sheet manufactured in the examples and comparative examples, and attach the exposed adhesive layer to an easy-adhesive layer of a polyethylene terephthalate (PET) film (manufactured by TOYOBO CO., LTD., product name "COSMOSHINE A4360", thickness: 100 μm) with easy-adhesive layers on both sides, to obtain a laminate of release sheet R1 / adhesive layer / PET film. Cut the laminate to a size of 25 mm wide and 100 mm long and use it as a sample.

[0187] Under conditions of 23°C and 50%RH, the release tab R1 was peeled off from the above sample, and the exposed adhesive layer was attached to soda-lime glass (manufactured by Nippon Sheet Glass Co., Ltd.). The mixture was then pressurized for 20 minutes at 0.5 MPa and 50°C using an autoclave manufactured by Kurihara Seisakusho. Then, through the soda-lime glass, the adhesive layer was irradiated with active energy rays (ultraviolet; UV) under the same conditions as in Test Example 1 to cure the adhesive layer.

[0188] Then, after being placed at 23°C and 50%RH for 24 hours, the adhesion (N / 25mm) was measured using a tensile testing machine (manufactured by ORIENTEC, TENSILON) at a peel speed of 300 mm / min and a peel angle of 180 degrees. Conditions not described here were measured according to JIS Z0237:2009. The results are shown in Table 2.

[0189] [Experimental Example 7] (Evaluation of Anti-foaming Properties) Peel off release tab R2 from the adhesive sheet manufactured in the examples and comparative examples, and attach the exposed adhesive layer (50 μm thick) to the PC board side of a plastic sheet (manufactured by MITSUBISHI GAS CHEMICAL COMPANY, INC., product name "Iupilon sheet MR58U", thickness: 0.7 mm) on which a polymethyl methacrylate (PMMA) layer is laminated on a polycarbonate (PC) board. Then, peel off release tab R1 from the adhesive layer to expose the adhesive layer, and attach a transparent conductive film (manufactured by OIKE&Co., Ltd., a laminate of PET film and ITO layer (ITO-PET film, total thickness 125 μm) with its ITO layer side in contact with the adhesive layer. Then, perform a heat treatment at 50°C and 0.5 MPa for 20 minutes.

[0190] The adhesive layer of the obtained laminate was cured by irradiating it with active energy rays (ultraviolet; UV) through the aforementioned transparent conductive film under the same conditions as in Example 1. It was then placed at ambient pressure, 23°C, and 50% RH for 24 hours and used as a sample.

[0191] The obtained samples were stored at 85°C and 85%RH for 72 hours. The interface between the adhesive layer and the substrate (plastic sheet) was then visually inspected, and the anti-foaming properties were evaluated using the following benchmarks. The results are shown in Table 2. ◎...No bubbles were produced or the bubbles floated. ○… It produces bubbles with a diameter of less than 5mm, which float up, but it is of a practically usable grade. The grade that produces bubbles larger than 5mm in diameter and floats is unusable in practice.

[0192] [Experimental Example 8] (Evaluation of Segment Followership) UV-curable ink (manufactured by Teikoku Printing Inks Mfg. Co., Ltd., product name "POS-911 BLACK") was screen-printed to a specified thickness onto the surface of a glass plate (manufactured by NSG Precision Cells, Inc., product name "Corning Glass EAGLE XG", 90mm long × 50mm wide × 0.5mm thick) in a frame shape (90mm long × 50mm wide × 0.5mm thick). Then, it was irradiated with ultraviolet light (80W / cm²). 2 Two metal halide lamps, each 15cm high, are used to cure the printed UV-curable ink, creating a glass plate with stepped heights (any of the following heights: 5μm, 10μm, 15μm, 20μm, or 25μm) caused by printing.

[0193] Peel release tab R2 from the adhesive sheet manufactured in the examples and comparative examples, and adhere the exposed adhesive layer (50 μm thick) to the easy-adhesive layer of a polyethylene terephthalate (PET) film (manufactured by TOYOBO CO., LTD., product name "COSMOSHINE A4360", thickness: 100 μm) with an easy-adhesive layer. Next, peel release tab R1 to expose the adhesive layer, and laminate it onto each stepped glass plate using a laminator (manufactured by Fujipla Inc., product name "LPD3214") so that the adhesive layer covers the entire frame-shaped printed surface. Then, perform a pressure heat treatment at 50°C and 0.5 MPa for 20 minutes, and place at atmospheric pressure, 23°C, and 50% RH for 24 hours.

[0194] Next, the adhesive layer was cured by irradiating it with active energy rays under the same conditions as in Example 1, through the aforementioned PET film. Then, it was stored at 85°C and 85%RH for 120 hours (durability test) to evaluate step followability. Step followability was judged by whether the printed steps were completely filled by the adhesive layer. When bubbles, floating, or peeling were observed at the interface between the printed steps and the adhesive layer, it was judged as failure to follow the printed steps. Here, the step followability rate (%) shown in the following formula was used to evaluate step followability. The results are shown in Table 2. Step follow-through rate (%) = {(Height of the step that remains in the landfill state without bubbles, buoyancy, peeling, etc. after the durability test (μm)) / (Thickness of the adhesive layer)} × 100 ○…The segment difference following rate is over 40%. ×… The segment difference following rate is less than 40%.

[0195] [Table 1]

[0196] [Table 2]

[0197] As shown in Table 2, the adhesive sheet manufactured in the examples can suppress yellowing of the adhesive layer at the ends of the laminate. Industrial applicability

[0198] The adhesives and adhesive sheets of the present invention can be suitably used, for example, in the manufacture of a display body to protect the bonding of display body components such as panels to the desired display body components. Explanation of reference numerals in the attached figures

[0199] 1: Adhesive sheet; 11: Adhesive layer; 12a, 12b: Release sheet; 2: Display body; 21: First display body component; 22: Second display body component; 3: Printed layer.

Claims

1. An adhesive containing an oxygen absorber and used for optical applications, characterized in that, When a laminate consisting of two 1.1 mm thick, 7.0 cm square soda-lime glass plates bonded together with a 250 μm thick adhesive layer formed by the adhesive is placed under a durability condition of immersion in an atmosphere at 140°C for 100 hours, the adhesive layer before the durability condition is compared with that of CIE1976L. a b The color b specified in the color system Let b be the value of b.

1. And the adhesive layer at the end of the laminate after the durability condition is determined by CIE1976L a b The color b specified in the color system Let b be the value of b.

2. At this time, the b 2 relative to b The absolute value of the ratio of 1 to 4.5 is less than 1.

2. An adhesive containing an oxygen absorber and used for optical applications, characterized in that, When a laminate consisting of two 1.1 mm thick, 7.0 cm square soda-lime glass plates bonded together with a 250 μm thick adhesive layer formed by the adhesive is placed in an atmosphere at 140°C for 100 hours under durability conditions, the adhesive layer at the ends of the laminate after the durability condition is compared with CIE1976L. a b The color b specified in the color system Let b be the value of b. At time 2, the b The absolute value of 2 is less than 2.

0.

3. An adhesive containing an oxygen absorber and used for optical applications, characterized in that, When a laminate consisting of two 1.1 mm thick, 7.0 cm square soda-lime glass plates bonded together with a 250 μm thick adhesive layer formed by the adhesive is placed in an atmosphere at 140°C for 100 hours under durability conditions, the adhesive layer at the ends of the laminate after the durability condition is compared with CIE1976L. a b The color b specified in the color system Let b be the value of b.

2. And the adhesive layer in the central portion of the laminate after the durability condition is determined by CIE1976L a b The color b specified in the color system Let b be the value of b.

3. At this time, the b 2 relative to b The absolute value of the ratio of 3 is less than 2.

5.

4. The adhesive according to any one of claims 1 to 3, characterized in that, The oxygen absorbent is a compound represented by the following general formula (I). [Chemical Formula 1] ， In general formula (I), X and Y each independently represent a chalcogenide atom, and R 1 R 2 R 7 and R 8 Each independently represents any one of alkyl, alkenyl, aryl, and aralkyl groups having 1 to 6 carbon atoms, R 3 R 4 R 5 and R 6 Each of the following independently represents any one of hydrogen atom, alkyl group having 1 to 6 carbon atoms, alkenyl group having 2 to 6 carbon atoms, aryl group, and aralkyl group; J represents a linking group consisting of an aliphatic hydrocarbon having 3 to 15 carbon atoms, wherein any carbon atom of the linking group is optionally replaced by an oxygen atom, or the linking group is optionally substituent for at least one of the group consisting of hydroxyl, (meth)acryloyloxy, styryloxy, and alkenyloxy having 2 to 5 carbon atoms; n is any integer from 1 to 5; and when multiple Y and R are present... 5 R 6 R 7 and R 8 When, they can be chosen to be different atoms or groups.

5. The adhesive according to any one of claims 1 to 3, characterized in that, The oxygen absorbent is a compound represented by the following general formula (II). [Chemical Formula 2] ， In general formula (II), R 9 R represents a hydrogen atom or a methyl group. 10 It represents any one of hydroxyl, (meth)acryloyloxy, styryloxy, and alkenyloxy with 2 to 5 carbon atoms; R 11 R 12 R 13 and R 14 Each can independently represent any one of alkyl, alkenyl, aryl, and aralkyl groups having 1 to 6 carbon atoms.

6. The adhesive according to any one of claims 1 to 3, characterized in that, The oxygen absorbent is a compound represented by the following formula (III). [Chemical Formula 3] 。 7. The adhesive according to any one of claims 1 to 3, characterized in that, The adhesive is an acrylic adhesive.

8. The adhesive according to any one of claims 1 to 3, characterized in that, The adhesive is a (meth)acrylate polymer or its crosslinked product.

9. The adhesive according to any one of claims 1 to 3, characterized in that, The adhesive is an adhesive that can be cured by active energy rays.

10. An adhesive sheet having an adhesive layer for bonding two components together, characterized in that, At least one of the components is an optical component. The adhesive layer is composed of the adhesive according to any one of claims 1 to 3.

11. The adhesive sheet according to claim 10, characterized in that, The adhesive sheet has two release tabs, and the adhesive layer is clamped by the release tabs in such a way that it contacts the release surfaces of the two release tabs.

12. An optical assembly comprising at least two components bonded together using an adhesive layer, characterized in that, At least one of the components is an optical component. The adhesive layer is formed from the adhesive according to any one of claims 1 to 3.

13. A display body comprising: A display body constitutes a component; Another display component; and An adhesive layer that bonds one display component to the other display component. The display body is characterized in that... The adhesive layer is formed from the adhesive layer of the adhesive sheet as described in claim 10.

14. The display body according to claim 13, characterized in that, Both the one display component and the other display component are made of rigid board.

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