Photoactivated adhesive composition, adhesive sheet, roll body, and method of using adhesive sheet

Abstract

To provide a photoactivated adhesive composition which is excellent in controllability of adhesive physical properties before and after light irradiation, when formed into a molding, and also to provide an adhesive sheet, a roll body, and a method of using an adhesive sheet, which employ the photoactivated adhesive composition.SOLUTION: A photoactivated adhesive composition contains (A) at least one resin selected from the group consisting of an acrylic resin, a polyester-based resin, and a rubber-based resin, and (B) an azobenzene derivative having a specific structure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a photoactivatable pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet, a roll, and a method for using the pressure-sensitive adhesive sheet. [Background technology]

[0002] Adhesives have been proposed that utilize the phenomenon in which compounds reversibly become fluid and non-fluid upon exposure to light, allowing for reversible bonding and detachment. These materials are attracting attention as environmentally friendly materials because they allow for the reuse or recycling of adherends after detachment.

[0003] As an example of such technology, Patent Document 1 discloses a photoresponsive adhesive whose main component is a sugar alcohol derivative having liquid crystallinity and into which an azobenzene derivative has been introduced as a photoresponsive moiety. Patent Document 2 also discloses a photoresponsive adhesive that uses a block copolymer polymer that is composed of a moiety made of a polymer liquid crystal compound containing an azobenzene moiety and a separate moiety made of a flexible polymer that is light-transmitting, non-photoresponsive, and has a glass transition point and melting point below room temperature. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2013 / 168712 [Patent Document 2] International Publication No. 2017 / 119412 Summary of the Invention [Problem to be solved by the invention]

[0005] From the viewpoint of reducing waste, photoresponsive adhesive sheets are expected to have a linerless structure that does not require a component (release liner) to protect the adhesive layer, and to have reworkability when aligning the application position. On the other hand, there is a demand for them to exhibit adhesive properties that allow them to firmly adhere to the adherend during use. However, conventional technologies have a problem in that it is difficult to control the adhesive properties before and after light irradiation.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a photoactivatable pressure-sensitive adhesive composition that, when formed into a molded product, has excellent control over adhesive properties before and after light irradiation, as well as a pressure-sensitive adhesive sheet and roll body using the same, and a method for using the pressure-sensitive adhesive sheet. [Means for solving the problem]

[0007] As a result of intensive research into achieving the above-mentioned object, the inventors discovered that a photoactivatable adhesive composition containing at least one resin selected from the group consisting of acrylic resins, polyester resins, and rubber resins, and a specific azobenzene derivative, led to the completion of the present invention.

[0008] That is, the present invention is as follows.

[0009] (1) The photoactivatable pressure-sensitive adhesive composition contains (A) at least one resin selected from the group consisting of acrylic resins, polyester resins, and rubber resins, and (B) an azobenzene derivative represented by formula (1).

[0010] [ka]

[0011] (In the formula, R 1 ~R 10 each independently represents a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen atom, an amino group, an acetyl group, a nitro group, or an unbranched or branched alkoxy group having 8 to 20 carbon atoms, provided that R1 ~R 10 At least one of the groups is an unbranched or branched alkoxy group having 8 to 20 carbon atoms.) (2) The photoactivatable pressure-sensitive adhesive composition according to (1), wherein the azobenzene derivative (B) is 1-phenyl-2-[4-(tetradecyloxy)phenyl]diazene. (3) The photoactivatable pressure-sensitive adhesive composition according to (1) or (2), wherein the mass ratio of the content of the azobenzene derivative (B) to the content of the resin (A) is 0.02 to 1. (4) (1) A pressure-sensitive adhesive sheet comprising a photoactivatable pressure-sensitive adhesive layer containing the photoactivatable pressure-sensitive adhesive composition described above. (5) The pressure-sensitive adhesive sheet according to (4) above has a photoactivatable pressure-sensitive adhesive layer on at least a portion of one or both sides of a non-releasable substrate, and is linerless, i.e., does not have a release liner on the surface of the photoactivatable pressure-sensitive adhesive layer. (6) The pressure-sensitive adhesive sheet according to (4) or (5), wherein the ratio (A2 / A1) of the adhesive strength A2 after ultraviolet irradiation to the adhesive strength A1 before ultraviolet irradiation is 10 or more. (7) A roll body in which the pressure-sensitive adhesive sheet according to (4) or (5) is wound around a core. (8) A method for using a pressure-sensitive adhesive sheet, comprising: a step of irradiating ultraviolet light onto at least a portion of the surface of the photoactivatable pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet described in (4) or (5) to develop or improve the adhesiveness of the photoactivatable pressure-sensitive adhesive layer; and a step of attaching the photoactivatable pressure-sensitive adhesive layer irradiated with ultraviolet light to the surface of an adherend. (9) A method for using a pressure-sensitive adhesive sheet, comprising: a step of contacting at least a portion of the surface of the photoactivatable pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet described in (4) or (5) with an adherend; and a step of irradiating with ultraviolet light at least a portion of the surface of the pressure-sensitive adhesive sheet opposite the contact surface with the adherend and / or at least a portion of the surface of the adherend opposite the contact surface with the pressure-sensitive adhesive sheet, thereby developing or improving the adhesiveness of at least a portion of the contact surface of the photoactivatable pressure-sensitive adhesive layer, thereby attaching the pressure-sensitive adhesive sheet to the adherend. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a photoactivatable pressure-sensitive adhesive composition that, when formed into a molded article, exhibits excellent control over adhesive properties before and after light irradiation, as well as a pressure-sensitive adhesive sheet and roll body using the same, and a method for using the pressure-sensitive adhesive sheet. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view showing an example of the pressure-sensitive adhesive sheet according to this embodiment. [Figure 2] FIG. 2 is a flow diagram showing a first method of using the pressure-sensitive adhesive sheet according to this embodiment. [Figure 3] FIG. 3 is a conceptual diagram illustrating an example of a first method of using the pressure-sensitive adhesive sheet according to this embodiment. [Figure 4] FIG. 4 is a flow diagram showing a second method of using the pressure-sensitive adhesive sheet according to this embodiment. [Figure 5] FIG. 5 is a conceptual diagram illustrating an example of a second method of using the pressure-sensitive adhesive sheet according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out by appropriately modifying it within the scope of its gist.

[0015] In the drawings, the same elements are given the same reference numerals, and redundant explanations will be omitted. Furthermore, unless otherwise specified, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to the ratios shown in the drawings.

[0016] Furthermore, unless otherwise specified, the term "sheet" in this specification also includes what is called a "film," etc. Similarly, the term "film" in this specification also includes what is called a "sheet," etc.

[0017] Furthermore, in this specification, unless otherwise specified, "(meth)acrylic" includes methacrylic and acrylic, and "(meth)acrylate" includes methacrylate and acrylate. For example, (meth)acrylic means methacrylic, acrylic, or both.

[0018] 1. Light-activatable adhesive composition

[0019] The photoactivatable pressure-sensitive adhesive composition according to the present embodiment contains (A) at least one resin selected from the group consisting of acrylic resins, polyester resins, and rubber resins (hereinafter, sometimes simply referred to as "(A) resin" or "(A) component"), and (B) an azobenzene derivative represented by formula (1) (hereinafter, sometimes simply referred to as "(B) azobenzene derivative" or "(B) component").

[0020] [ka]

[0021] (In the formula, R 1 ~R 10 each independently represents a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen atom, an amino group, an acetyl group, a nitro group, or an unbranched or branched alkoxy group having 8 to 20 carbon atoms, provided that R 1 ~R 10At least one of the groups is an unbranched or branched alkoxy group having 8 to 20 carbon atoms.)

[0022] The photoactivatable pressure-sensitive adhesive composition according to the present embodiment, when formed into a molded article, can exhibit or improve its adhesive strength by irradiation with ultraviolet light. A pressure-sensitive adhesive sheet using the photoactivatable pressure-sensitive adhesive composition having such properties can adhere to an adherend due to the exhibited or improved adhesive strength.

[0023] Unless otherwise specified, the term "molded article" as used herein refers to a molded article obtained from a photoactivatable pressure-sensitive adhesive composition, and the molding method is not limited. Thus, for example, when the photoactivatable pressure-sensitive adhesive composition itself is a solid or solid having a certain shape retention, the composition itself can also be included in the "molded article." Alternatively, when the photoactivatable pressure-sensitive adhesive composition has fluidity or is liquid due to the inclusion of a solvent as described below, a product obtained by molding the composition into a solid or solid form by, for example, distilling off the solvent from the composition is also included in the "molded article." Needless to say, examples of the "molded article" include film-like products, photoactivatable pressure-sensitive adhesive layers as described below, and pressure-sensitive adhesive sheets.

[0024] A preferred example of the photoactivatable pressure-sensitive adhesive composition according to this embodiment is one in which the photoactivatable pressure-sensitive adhesive composition or a molded product thereof has no or low adhesive strength before irradiation with ultraviolet light, and can exhibit or improve adhesive strength by irradiation with at least ultraviolet light, thereby exhibiting the desired adhesiveness.

[0025] The reason why the photoactivatable pressure-sensitive adhesive composition or molded article thereof according to the present embodiment exhibits or improves adhesive strength upon UV irradiation is unclear, but is thought to be as follows. Before UV irradiation, the photoactivatable pressure-sensitive adhesive composition or molded article is, for example, incompatible with the (A) resin and the (B) azobenzene derivative, or their compatibility is low. Therefore, their independent existence is thought to reduce adhesive strength. Then, upon UV irradiation, the (A) resin and the (B) azobenzene derivative become compatible with each other or their compatibility is improved, which is thought to enable the exhibiting or improvement of strong adhesive strength. This is thought to be because UV irradiation causes the (B) azobenzene derivative in the (A) resin to undergo a photoisomerization reaction, resulting in crystalline melting, or this is accelerated, thereby promoting compatibility with the (A) resin. As a result, the flexibility of the adhesive layer, etc., formed by the photoactivatable adhesive composition or molded article is also increased, and the ability to conform to the surface of the adherend (e.g., adhesion, etc.) is improved, which is thought to result in the development or improvement of adhesive strength (however, the actions and effects of this embodiment are not limited to these).

[0026] In a preferred aspect of this embodiment, the difference in adhesive strength between before and after UV irradiation can be increased. Therefore, before UV irradiation, the photoactivatable pressure-sensitive adhesive composition or its molded article can be stored in a state where the adhesive strength is reduced, and when it is desired to develop adhesiveness at the time of use, the desired adhesiveness can be developed by UV irradiation (however, the method of use according to this embodiment is not limited to this).

[0027] The photoactivatable pressure-sensitive adhesive composition according to the present embodiment can be photoactivated using energy rays such as ultraviolet light to develop or improve adhesive properties. The use of ultraviolet light can effectively develop or improve adhesive strength. This is presumably because, for example, it can efficiently promote the photoisomerization reaction of the (B) azobenzene derivative and improve the compatibility between the (A) resin and the (B) azobenzene derivative. Other advantages, such as being preferable from the standpoint of productivity and energy conservation compared to heating, can also be expected (although the functions and effects according to the present embodiment are not limited to these).

[0028] The type of ultraviolet light can be selected taking into consideration the intended use and the types of components contained in the photoactivatable pressure-sensitive adhesive composition, and examples thereof include near-ultraviolet light and far-infrared light. The wavelength of the ultraviolet light is not particularly limited, and is preferably selected taking into consideration the absorption wavelength of the substrate used and the components contained in the photoactivatable pressure-sensitive adhesive composition, but is typically preferably 10 to 450 nm. The lower limit of the wavelength is more preferably 250 nm or more, and even more preferably 300 nm or more. The upper limit of the wavelength is more preferably 420 nm or less, and even more preferably 400 nm or less. The source of the ultraviolet light is not particularly limited, and known light sources can be used. The light source is not particularly limited, and examples thereof include low-pressure mercury lamps, high-pressure mercury lamps, metal halide lamps, and UV-LED lamps.

[0029] Furthermore, since the photoactivatable pressure-sensitive adhesive composition according to this embodiment contains the resin (A), it can be easily molded into a sheet or the like, and therefore has excellent moldability. The method for molding into a sheet will be described later.

[0030] Each component of the pressure-sensitive adhesive composition according to this embodiment will be described below.

[0031] <(A) Resin>

[0032] The photoactivatable pressure-sensitive adhesive composition according to the present embodiment contains (A) at least one resin selected from the group consisting of acrylic resins, polyester resins, and rubber resins. The (A) resin preferably has adhesive strength at 23°C. From the viewpoint of compatibility with the (B) azobenzene derivative in the composition before and after UV irradiation, the (A) resin preferably does not contain an azobenzene structure. For example, the (A) resin preferably does not contain an azobenzene structure in the side chain of the polymer. Furthermore, the monomer constituting the (A) resin preferably does not contain an azobenzene structure. Furthermore, for example, a chemically crosslinked polymer compound can also be used as the resin.

[0033] Specific examples of acrylic resins include, but are not limited to, those containing (meth)acrylic acid, (meth)acrylic acid alkyl esters, and / or (meth)acrylonitrile as structural units. Examples of acrylic resins include homopolymers or copolymers of (meth)acrylic acid, (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, and (meth)acrylonitrile. Copolymers also include copolymers composed of two types of monomers and multi-component copolymers composed of three or more types of monomers.

[0034] When the acrylic resin is a copolymer, the above-mentioned (meth)acrylic acid, (meth)acrylic acid alkyl ester, and (meth)acrylonitrile preferably account for 50 mol% or more of all structural units. When two or more of (meth)acrylic acid, (meth)acrylic acid alkyl ester, and (meth)acrylonitrile are used in combination, the total amount thereof is preferably 50 mol% or more. Furthermore, when the acrylic resin is a copolymer, examples of monomers other than the above-mentioned (meth)acrylic acid, (meth)acrylic acid alkyl ester, and (meth)acrylonitrile include styrene-based monomers such as styrene, α-methylstyrene, and vinyltoluene, maleic acid, vinyl acetate, and vinyl ketone.

[0035] The polyester resin is not particularly limited, and examples thereof include aromatic polyester resins and aliphatic polyester resins. Polyester resins are produced, for example, by polycondensation of a polycarboxylic acid component and a polyol component in the presence of a catalyst. Examples of the polycarboxylic acid component include aliphatic and alicyclic dicarboxylic acids such as adipic acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, dodecenylsuccinic anhydride, fumaric acid, succinic acid, dodecanedioic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, maleic acid, maleic anhydride, itaconic acid, and citraconic acid; and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 2,2'-diphenyldicarboxylic acid, and 4,4'-diphenyletherdicarboxylic acid. Examples of the polyol component include dihydric alcohols and polyhydric alcohols such as aliphatic glycols and alicyclic glycols. Specific examples of aliphatic glycols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, neopentyl glycol, 3-methylpentanediol, 2,2,3-trimethylpentanediol, diethylene glycol, triethylene glycol, and dipropylene glycol. Specific examples of alicyclic glycols include 1,4-cyclohexanedimethanol and hydrogenated bisphenol A.

[0036] The rubber-based resin is not particularly limited, but examples thereof include synthetic rubber and natural rubber. Examples of synthetic rubber include thermoplastic elastomers such as styrene-isoprene-styrene copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-butadiene copolymer (SB), styrene-isoprene copolymer (SI), styrene-ethylene-butylene copolymer (SEB), styrene-ethylene-propylene copolymer (SEP), styrene-butadiene rubber (SBR), ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), and mixtures thereof (e.g., mixtures of polypropylene and ethylene-propylene-diene rubber (EPDM)); and synthetic rubbers such as isoprene rubber, polybutene rubber, butyl rubber, and acrylic rubber. Examples of synthetic rubbers that can be used include those used as synthetic rubber-based hot-melt adhesives. As the type of resin for the synthetic rubber-based hot melt adhesive, for example, the same type of resin as the above-mentioned synthetic rubber can be used.

[0037] These may be used alone or in combination of two or more.

[0038] (A) The glass transition temperature (T g) is not particularly limited, but is preferably -70°C to 20°C from the viewpoint of developing or improving adhesiveness after light irradiation. The lower limit is more preferably -40°C or higher, and even more preferably -30°C or higher. The upper limit is more preferably 10°C or lower, and even more preferably 0°C or lower. This allows for more effective control of the desired adhesive strength when the photoactivatable adhesive composition is made into an adhesive sheet. The glass transition temperature is the temperature at the maximum point of tan δ (loss modulus / storage modulus) when viscoelasticity is measured by the torsional shear method using a viscoelasticity measuring device ("MCR301" manufactured by Anton Paar) by heating a sample of the adhesive layer measuring 8 mm in diameter and 1 mm in thickness from -80 to 150°C at 1 Hz and a heating rate of 5°C / min.

[0039] (A) Among resins, the glass transition temperature (T g ) is more preferably -30°C to 0°C. In the case of polyester resins, the glass transition temperature (T g ) is more preferably -50°C to 0°C.

[0040] (A) The weight average molecular weight (M w ) is not particularly limited, but is usually preferably 50,000 to 1,000,000. The lower limit is more preferably 100,000 or more, and even more preferably 200,000 or more. The upper limit is more preferably 800,000 or less, and even more preferably 500,000 or less. In addition, the weight average molecular weight (M w The weight average molecular weight (M) is preferably 10,000 to 100,000. w ) are values ​​calculated as standard polystyrene molecular weights measured by gel permeation chromatography (GPC) unless otherwise specified.

[0041] The adhesive strength of the (A) resin at 23° C. is preferably 3 to 40 N / 25 mm. This adhesive strength is measured in accordance with JIS Z 0237:2009 when a test piece is peeled at an angle of 180° at a peel rate of 300 mm / min.

[0042] <(B) Azobenzene Derivative>

[0043] The photoactivatable pressure-sensitive adhesive composition according to this embodiment contains (B) an azobenzene derivative represented by formula (1).

[0044] [ka]

[0045] (In the formula, R 1 ~R 10 each independently represents a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen atom, an amino group, an acetyl group, a nitro group, or an unbranched or branched alkoxy group having 8 to 20 carbon atoms, provided that R 1 ~R 10 At least one of the groups is an unbranched or branched alkoxy group having 8 to 20 carbon atoms.)

[0046] The azobenzene derivative (B) represented by the above formula (1) is a compound that can undergo photoisomerization, polarity change, and / or molecular size change due to a photoisomerization reaction caused by ultraviolet irradiation. When the photoactivatable pressure-sensitive adhesive composition according to this embodiment is irradiated with ultraviolet light or the like, a photoisomerization reaction of the azobenzene derivative (B) occurs, which is thought to cause crystalline melting and improve compatibility with the resin (A) (however, the functions and effects according to this embodiment are not limited to these).

[0047] R in Equation (1) 1 ~R 10At least one of the R groups is an unbranched or branched alkoxy group having 8 to 20 carbon atoms. The upper limit of the number of carbon atoms in the alkoxy group is preferably 18 or less, more preferably 16 or less, and even more preferably 15 or less. The lower limit of the number of carbon atoms in the alkoxy group is preferably 9 or more, more preferably 10 or more, and even more preferably 11 or more. The alkoxy group may be either an unbranched alkoxy group or a branched alkoxy group, but is preferably an unbranched alkoxy group (the alkyl group is linear). R in formula (1) 1 ~R 10 When at least one of the groups is such an alkoxy group, the azobenzene derivative (B) has crystallinity and can be easily controlled to exist in a solid state in the resin (A) before UV irradiation.

[0048] In addition, R in Eq. (1) 1 ~R 10 are each independently a group selected from the group consisting of a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen atom, an amino group, an acetyl group, a nitro group, and an unbranched or branched alkoxy group having 8 to 20 carbon atoms. From the viewpoint that compatibility between (A) resin and (B) azobenzene derivative can be effectively exhibited or improved by a photoisomerization reaction due to ultraviolet irradiation, R 1 ~R 10 Among these, the group other than the unbranched or branched alkoxy group having 8 to 20 carbon atoms is preferably a hydrogen atom, a hydrocarbon group (for example, an alkyl group), or a halogen group, more preferably a hydrogen atom or an alkyl group.

[0049] Suitable examples of formula (1) include, for example, R 1 ~R 10 At least one of R is an unbranched or branched alkoxy group having 8 to 20 carbon atoms, and the other R 1 ~R 10 is preferably a hydrogen atom or an alkyl group; 1 ~R 10At least one of R is an unbranched alkoxy group having 8 to 20 carbon atoms, and the other R 1 ~R 10 is more preferably an azobenzene derivative in which R is a hydrogen atom or an alkyl group; 1 ~R 10 At least one of R is an unbranched alkoxy group having 11 to 15 carbon atoms, and the other R 1 ~R 10 More preferred are azobenzene derivatives in which is a hydrogen atom or an alkyl group.

[0050] In addition, R in Eq. (1) 1 ~R 10 When any of R is an alkoxy group, the number of alkoxy groups is preferably 1 or 2. For example, R 1 ~R 10 It is preferable that one or two of R is an alkoxy group. The position of the alkoxy group is determined by 3 and / or R 8 It is preferable that at least one of the groups is an alkoxy group.

[0051] Furthermore, R in formula (1) 1 ~R 10 When any of R is the above alkyl group, the number of alkyl groups is preferably 1 or 2. For example, R 1 ~R 10 When any of R is an alkyl group as described above, R 1 ~R 10 Preferably, one or two of R are alkyl groups. 1 ~R 10 When either of the above is an alkyl group, the alkyl group is preferably a methyl group, an ethyl group, or a propyl group.

[0052] When the structure of formula (1) takes on each of the above-mentioned structures, the photoisomerization reaction due to ultraviolet irradiation is effectively promoted, and the compatibility with the (A) resin can be further improved, so that the adhesive strength can be more effectively expressed or improved (however, the actions and effects of this embodiment are not limited to these).

[0053] The (B) azobenzene derivative is preferably at least one selected from the group consisting of 1-phenyl-2-[4-(tetradecyloxy)phenyl]diazene, 1-phenyl-2-[4-(octadecyloxy)phenyl]diazene, 1-phenyl-2-[4-(dodecyloxy)phenyl]diazene, 1-phenyl-2-[4-(decyloxy)phenyl]diazene, 1-phenyl-2-[4-(octyloxy)phenyl]diazene, and 4,4'-didodecyloxy-3-methylazobenzene, and more preferably 1-phenyl-2-[4-(tetradecyloxy)phenyl]diazene. By using such a compound, the (A) resin and the (B) azobenzene derivative become compatible or their compatibility is improved by irradiating the photoactivatable pressure-sensitive adhesive composition (or a molded product thereof) with ultraviolet light due to a photoisomerization reaction caused by ultraviolet light irradiation, thereby more effectively exhibiting or improving adhesive strength.

[0054] These may be used alone or in combination of two or more.

[0055] <(C) Crosslinking Agent>

[0056] The photoactivatable pressure-sensitive adhesive composition according to this embodiment may further contain a (C) crosslinking agent. As the (C) crosslinking agent, a polyfunctional compound reactive with the functional groups of the (A) resin or the like can be used. Specific examples of such polyfunctional compounds include isocyanate compounds, epoxy compounds, amine compounds, melamine compounds, aziridine compounds, hydrazine compounds, aldehyde compounds, oxazoline compounds, metal alkoxide compounds, metal chelate compounds, metal salts, ammonium salts, and reactive phenolic resins. Among these crosslinking agents, isocyanate compounds, epoxy compounds, and metal chelates are preferably used from the viewpoint of pot life. Examples of crosslinking agents containing an isocyanate compound include tolylene diisocyanate crosslinking agents, hexamethylene diisocyanate crosslinking agents, and paraxylene diisocyanate crosslinking agents.

[0057] <(D) Other additives>

[0058] The photoactivatable pressure-sensitive adhesive composition according to this embodiment may further contain (D) other additives, provided that the effects and advantages of this embodiment are not impaired. Examples of (D) other additives include known additives such as antistatic agents, antioxidants, softeners, fillers (e.g., fillers), colorants (e.g., pigments, dyes), tackifiers, reaction retarders, crosslinking accelerators, photosensitizers, and silane coupling agents.

[0059] Examples of tackifiers include rosin resins, hydrogenated rosin resins, terpene phenol resins, terpene resins, hydrogenated terpene resins, aromatic hydrocarbon-modified terpene resins, petroleum resins, coumarone-indene resins, styrene-based resins, phenol-based resins, xylene resins, etc. Among these, it is preferable to use one or more selected from rosin resins and terpene resins, which are plant-derived resins.

[0060] These additives may be used alone or in combination of two or more. When two or more types are used, the combination and ratio thereof may be selected arbitrarily. The content of the additive is not particularly limited and may be appropriately selected in consideration of the type, purpose, etc.

[0061] <(E) Solvent>

[0062] The photoactivatable pressure-sensitive adhesive composition according to this embodiment may further contain a solvent. Examples of the solvent include organic solvents. Specific examples of organic solvents include alcohols (e.g., methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-methyl-1-propanol, 2-butanol, 2-methyl-2-propanol, diacetone alcohol, and benzyl alcohol), ketones (e.g., acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone), ethers (e.g., diethyl ether, dioxane, and tetrahydrofuran), cellosolves (e.g., methyl cellosolve and ethyl cellosolve), esters (e.g., ethyl acetate, n-butyl acetate, ethyl butyrate, n-butyl glycolate, and diethylene glycol monoacetate), halogenated hydrocarbons (e.g., chloroform, dichloromethane, tetrachloroethylene, and carbon tetrachloride), and hydrocarbons (e.g., n-hexane, cyclohexane, toluene, xylene, and Solvesso).

[0063] The solvent may be used alone or in combination of two or more kinds.

[0064] <Content etc.>

[0065] The content of the (A) resin in the photoactivatable pressure-sensitive adhesive composition is not particularly limited, but from the viewpoints of compatibility with the (B) azobenzene derivative and shape retention of the photoactivatable pressure-sensitive adhesive composition or a molded article thereof (e.g., effective suppression of bleeding of the (B) azobenzene derivative when molded), it is preferably 60 to 99 mass% relative to 100 mass% of the total solid content. The lower limit is more preferably 70 mass% or more, even more preferably 80 mass% or more, and even more preferably 85 mass% or more. The upper limit is more preferably 96 mass% or less, even more preferably 95 mass% or less, and even more preferably 94 mass% or less.

[0066] Here, "100% by mass of total solid content" refers to the total amount of solid components excluding solvents and the like being 100% by mass. For example, in the case of a photoactivatable pressure-sensitive adhesive composition containing only components (A) and (B), this refers to the case where the total of components (A) and (B) is 100% by mass. For example, in the case of a photoactivatable pressure-sensitive adhesive composition containing only components (A), (B), and (C), this refers to the case where the total of components (A), (B), and (C) is 100% by mass.

[0067] From the viewpoints of compatibility with the azobenzene derivative (B) and the shape retention of the photoactivatable pressure-sensitive adhesive composition or a molded article thereof upon ultraviolet irradiation, the content of the resin (A) in the photoactivatable pressure-sensitive adhesive composition is preferably 60 to 99% by mass relative to 100% by mass of the total of the components (A) and (B). The lower limit is more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 85% by mass or more. The upper limit is more preferably 96% by mass or less, even more preferably 95% by mass or less, and even more preferably 94% by mass or less.

[0068] Alternatively, from the viewpoints of compatibility with the azobenzene derivative (B) and the shape retention of the photoactivatable pressure-sensitive adhesive composition or a molded article thereof upon ultraviolet irradiation, the content of the resin (A) in the photoactivatable pressure-sensitive adhesive composition is preferably 60 to 99% by mass relative to 100% by mass of the total of the components (A), (B), and (C). The lower limit is more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 85% by mass or more. The upper limit is more preferably 96% by mass or less, even more preferably 95% by mass or less, and even more preferably 94% by mass or less.

[0069] By setting the content of the (A) resin within the above-mentioned range, the adhesive strength of the composition or a molded article thereof due to ultraviolet irradiation can be more effectively exhibited or improved. Furthermore, since it is possible to suppress the adhesive strength of the composition or a molded article thereof before ultraviolet irradiation to a low level, it is expected that the difference in the degree of adhesive strength exhibited or improved by ultraviolet irradiation can be further increased.

[0070] The content of the (B) azobenzene derivative in the photoactivatable pressure-sensitive adhesive composition is not particularly limited, but from the viewpoints of compatibility with the (A) resin and the shape retention of the photoactivatable pressure-sensitive adhesive composition or a molded article thereof upon ultraviolet irradiation, it is preferably 1 to 40 mass% relative to 100 mass% of the total solid content. The lower limit of this content is more preferably 2 mass% or more, even more preferably 3 mass% or more, and even more preferably 4 mass% or more. The upper limit of this content is more preferably 35 mass% or less, even more preferably 30 mass% or less, and even more preferably 25 mass% or less.

[0071] Furthermore, from the viewpoints of compatibility with the (A) resin and shape retention of the photoactivatable pressure-sensitive adhesive composition or a molded article thereof upon ultraviolet irradiation, the content of the (B) azobenzene derivative in the photoactivatable pressure-sensitive adhesive composition is preferably 1 to 40% by mass relative to 100% by mass of the total of the (A) and (B) components. The lower limit of this content is more preferably 2% by mass or more, even more preferably 3% by mass or more, and even more preferably 4% by mass or more. The upper limit of this content is more preferably 35% by mass or less, even more preferably 30% by mass or less, and even more preferably 25% by mass or less.

[0072] Alternatively, the content of the (B) azobenzene derivative in the photoactivatable pressure-sensitive adhesive composition is preferably 1 to 40% by mass, relative to 100% by mass of the total of the (A), (B), and (C) components, from the viewpoints of compatibility with the (A) resin and shape retention of the photoactivatable pressure-sensitive adhesive composition or a molded article thereof upon ultraviolet irradiation. The lower limit of this content is more preferably 2% by mass or more, even more preferably 3% by mass or more, and even more preferably 4% by mass or more. The upper limit of this content is more preferably 35% by mass or less, even more preferably 30% by mass or less, and even more preferably 25% by mass or less.

[0073] By setting the content of the (B) azobenzene derivative within the above-mentioned range, the adhesive strength of the composition or a molded article thereof due to ultraviolet irradiation can be more effectively exhibited or improved. Furthermore, since it is possible to suppress the adhesive strength of the composition or a molded article thereof before ultraviolet irradiation to a low level, it is expected that the difference in the degree of adhesive strength exhibited or improved by ultraviolet irradiation can be further increased.

[0074] The mass ratio (B / A) of the content of the azobenzene derivative (B) to the content of the resin (A) is not particularly limited, but from the viewpoints of compatibility with the resin (A) and the shape retention of the photoactivatable pressure-sensitive adhesive composition or a molded article thereof upon ultraviolet irradiation, it is preferably 0.02 to 1. The lower limit of this mass ratio is more preferably 0.05 or more, even more preferably 0.07 or more, and even more preferably 0.08 or more. The upper limit of this mass ratio is more preferably 0.8 or less, even more preferably 0.6 or less, and even more preferably 0.4 or less.

[0075] By setting the mass ratio (B / A) of the content of the azobenzene derivative (B) to the resin (A) within this range, the adhesive strength of the composition or a molded article thereof due to UV irradiation can be more effectively exhibited or improved. Furthermore, since it is possible to keep the adhesive strength of the composition or a molded article thereof low before UV irradiation, it is expected that the difference in the degree of adhesive strength exhibited or improved by UV irradiation can be further increased.

[0076] Furthermore, the photoactivatable pressure-sensitive adhesive composition of the present embodiment can control the degree of adhesive strength so that the composition or a molded product thereof will have the desired adhesive strength upon ultraviolet irradiation by controlling the content of the (B) azobenzene derivative and the mass ratio (B / A) of the content of the (B) azobenzene derivative to the content of the (A) resin according to the desired application.

[0077] The content of (C) crosslinking agent in the photoactivatable pressure-sensitive adhesive composition is not particularly limited, but from the viewpoints of compatibility with (A) resin and shape retention of the photoactivatable pressure-sensitive adhesive composition or a molded article thereof upon UV irradiation, it is preferably 0.01 to 10 mass% relative to 100 mass% of the total solid content. The lower limit of this content is more preferably 0.03 mass% or more, even more preferably 0.05 mass% or more, and even more preferably 0.07 mass% or more. The upper limit of this content is more preferably 8 mass% or less, even more preferably 6 mass% or less, even more preferably 4 mass% or less, and even more preferably 3 mass% or less.

[0078] The content of the (C) crosslinking agent in the photoactivatable pressure-sensitive adhesive composition is not particularly limited, but from the viewpoints of compatibility with the (A) resin and the shape retention of the photoactivatable pressure-sensitive adhesive composition or a molded article thereof upon UV irradiation, it is preferably 0.01 to 10% by mass relative to 100% by mass of the total of the (A) and (B) components. The lower limit of this content is more preferably 0.03% by mass or more, even more preferably 0.05% by mass or more, and even more preferably 0.07% by mass or more. The upper limit of this content is more preferably 8% by mass or less, even more preferably 6% by mass or less, even more preferably 4% by mass or less, and even more preferably 3% by mass or less.

[0079] The content of the (C) crosslinking agent in the photoactivatable pressure-sensitive adhesive composition is not particularly limited, but from the viewpoints of compatibility with the (A) resin and the shape retention of the photoactivatable pressure-sensitive adhesive composition or a molded article thereof upon UV irradiation, it is preferably 0.01 to 10% by mass relative to 100% by mass of the total of the (A), (B), and (C) components. The lower limit of this content is more preferably 0.03% by mass or more, even more preferably 0.05% by mass or more, and even more preferably 0.07% by mass or more. The upper limit of this content is more preferably 8% by mass or less, even more preferably 6% by mass or less, even more preferably 4% by mass or less, and even more preferably 3% by mass or less.

[0080] By setting the content of (C) crosslinking agent within the above range, the adhesive strength of the composition or a molded article thereof can be more effectively expressed or improved by ultraviolet irradiation. Furthermore, since the adhesive strength of the composition or a molded article thereof before ultraviolet irradiation can be further reduced, it is expected that the difference in the degree of adhesive strength expressed or improved by ultraviolet irradiation will be further increased.

[0081] The photoactivatable pressure-sensitive adhesive composition can be obtained by mixing the above-mentioned components. If necessary, the mixture may be diluted with the above-mentioned solvent. The mixing method is not particularly limited, and known methods can be used.

[0082] For example, the resin (A) may be a resin present in a polymer solution containing a resin and an organic solvent. Commercially available polymer solutions may also be used. Examples include "Nissetsu PE121" manufactured by Nippon Carbide Industries Co., Ltd., which is a polymer solution containing an acrylic resin. Other examples include "Nichigo Polyester (registered trademark) SNT" manufactured by Mitsubishi Chemical Corporation, which is a polymer solution containing a polyester resin. In this case, the above-mentioned solvent may be further added, or no solvent may be added.

[0083] As described above, the photoactivatable pressure-sensitive adhesive composition according to this embodiment has the property that, when formed into a composition or a molded article, adhesive strength can be developed or improved by ultraviolet irradiation. Furthermore, it is also possible to form a suitable embodiment in which the composition or molded article exhibits no or low adhesiveness before ultraviolet irradiation and develops or improves adhesive strength after ultraviolet irradiation. Therefore, molded articles obtained from the photoactivatable pressure-sensitive adhesive composition according to this embodiment can be used in various applications that utilize these properties. As a suitable example, the composition can be suitably used as a pressure-sensitive adhesive sheet whose adhesive strength is developed or improved by ultraviolet irradiation. Hereinafter, a pressure-sensitive adhesive sheet will be described as an example of a molded article.

[0084] 2. Adhesive sheet

[0085] The pressure-sensitive adhesive sheet according to the present embodiment preferably comprises a photoactivatable pressure-sensitive adhesive layer containing a photoactivatable pressure-sensitive adhesive composition (hereinafter, the photoactivatable pressure-sensitive adhesive layer may be simply referred to as the "pressure-sensitive adhesive layer"). The pressure-sensitive adhesive sheet according to the present embodiment may or may not comprise a non-releasable substrate on at least a portion of one surface (one side) of the pressure-sensitive adhesive layer (hereinafter, the non-releasable substrate may be simply referred to as the "substrate"). Furthermore, when the pressure-sensitive adhesive sheet according to the present embodiment comprises the substrate on at least a portion of one side of the pressure-sensitive adhesive layer, the pressure-sensitive adhesive sheet may or may not further comprise a release liner on at least a portion of the surface opposite to the surface in contact with the substrate. Note that a pressure-sensitive adhesive sheet without a release liner is sometimes referred to as a "linerless pressure-sensitive adhesive sheet" or the like. Furthermore, the pressure-sensitive adhesive sheet according to the present embodiment may be configured to comprise a pressure-sensitive adhesive layer on at least a portion of both sides of a non-releasable substrate (a so-called double-sided pressure-sensitive adhesive sheet). Furthermore, when the pressure-sensitive adhesive sheet according to this embodiment is a pressure-sensitive adhesive sheet without a substrate or a double-sided pressure-sensitive adhesive sheet, it may have a configuration in which a release liner is provided on at least a portion of at least one surface of the pressure-sensitive adhesive layer (pressure-sensitive adhesive layer / release liner), or a configuration in which release liners are provided on at least a portion of both surfaces of the pressure-sensitive adhesive layer (release liner / pressure-sensitive adhesive layer / release liner).

[0086] The pressure-sensitive adhesive sheet according to the present embodiment is preferably stored, transported, and / or used as a roll in which the pressure-sensitive adhesive sheet is wound around a core. As described above, the photoactivatable pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet has no or low adhesiveness at 23°C before UV irradiation, and therefore can be used as a roll even without a non-releasable substrate and / or release sheet. For example, because the pressure-sensitive adhesive sheet has no or low adhesiveness before UV irradiation, adhesion between wound sheets can be effectively prevented.

[0087] FIG. 1 is a cross-sectional view showing an example of the pressure-sensitive adhesive sheet according to this embodiment.

[0088] The pressure-sensitive adhesive sheet 1 according to this embodiment is preferably a linerless pressure-sensitive adhesive sheet 1 that has a photoactivatable pressure-sensitive adhesive layer 12 (hereinafter sometimes simply referred to as "pressure-sensitive adhesive layer 12") on at least a portion of one or both sides of a non-releasable substrate 10, and does not have a release liner on the surface of the photoactivatable pressure-sensitive adhesive layer 12. Note that while Fig. 1 illustrates a case in which the pressure-sensitive adhesive layer 12 is formed over the entire surface of one surface of the substrate 10, the pressure-sensitive adhesive layer 12 may be formed only on a portion of the surface of the substrate 10, if necessary.

[0089] The pressure-sensitive adhesive layer 12 can be in a solid state or a solid form with a certain degree of shape retention before UV irradiation. Therefore, because the pressure-sensitive adhesive layer 12 itself has a certain degree of shape retention, the pressure-sensitive adhesive sheet 1 can also be configured as a linerless sheet, i.e., without a release liner. Because a linerless pressure-sensitive adhesive sheet 1 does not use a release liner, the amount of waste can be reduced.

[0090] Although details of the method of use will be described later, the adhesive sheet 1 according to the present embodiment can (i) develop or improve the adhesive strength of the adhesive layer 12 by directly irradiating the surface of the adhesive layer 12 with ultraviolet light, or (ii) develop or improve the adhesive strength of the adhesive layer 12 by irradiating the surface of the base material 10 with ultraviolet light so that the ultraviolet light reaches the adhesive layer 12 through the base material 10.

[0091] The ultraviolet light may be irradiated onto the entire surface of the pressure-sensitive adhesive layer 12 or the substrate 10, or onto at least a portion of the surface of the pressure-sensitive adhesive layer 12 or the substrate 10. When a specific portion on one side of the pressure-sensitive adhesive sheet 1 is irradiated with ultraviolet light, the adhesive strength of the irradiated portion of the pressure-sensitive adhesive layer 12 can be expressed or improved. By limiting the portion to be irradiated with ultraviolet light in this way, it is possible to activate the azobenzene derivative (B) contained in the pressure-sensitive adhesive layer 12 only in the specific portion, which can be suitably used, for example, for transporting microchips.

[0092] The adhesive strength of the pressure-sensitive adhesive layer 12 at 23°C before UV irradiation is preferably 5 N / 25 mm or less. The adhesive strength is more preferably less than 0.01 N / 25 mm. By having an adhesive strength of less than 0.01 N / 25 mm, the pressure-sensitive adhesive layer 12 can be made substantially tack-free before UV irradiation, allowing for a linerless configuration without a release liner. Furthermore, when the pressure-sensitive adhesive layer 12 before UV irradiation exhibits adhesiveness, the lower limit of the adhesive strength at 23°C is preferably 0.01 N / 25 mm or more, more preferably 0.05 N / 25 mm or more. The upper limit of this adhesive strength is more preferably 3 N / 25 mm or less, and even more preferably 1 N / 25 mm or less.

[0093] The adhesive strength of the pressure-sensitive adhesive layer 12 at 23°C after UV irradiation is preferably 6 to 50 N / 25 mm. The lower limit of this adhesive strength is more preferably 6.5 N / 25 mm or more, and even more preferably 7 N / 25 mm or more. The upper limit is more preferably 45 N / 25 mm or less, even more preferably 43 N / 25 mm or less, still more preferably 40 N / 25 mm or less, and even more preferably 38 N / 25 mm or less. By ensuring that the adhesive strength is within this range, the desired level of adhesiveness can be achieved as a pressure-sensitive adhesive sheet.

[0094] The adhesive strength can be measured in accordance with the method specified in JIS Z 0237:2009 by peeling the test piece at an angle of 180° at a peel rate of 300 mm / min. Specifically, the adhesive strength can be measured in accordance with the method described in the examples.

[0095] The ratio (A2 / A1) of the adhesive strength A2 after UV irradiation to the adhesive strength A1 before UV irradiation of the photoactivatable adhesive layer 12 in the adhesive sheet 1 according to this embodiment is preferably 10 or more. The lower limit of this adhesive strength ratio is more preferably 15 or more, even more preferably 20 or more, even more preferably 25 or more, and even more preferably 30 or more. The upper limit of this adhesive strength ratio is not particularly limited, but is preferably 120 or less, more preferably 110 or less, even more preferably 105 or less, even more preferably 100 or less, and even more preferably 95 or less. When the ratio of adhesive strengths before and after UV irradiation (A2 / A1) is within the above-mentioned range, the adhesive strength can be minimized before use of the adhesive sheet, and the adhesiveness can be controlled to a desired level during use, making this an ideal adhesive sheet.

[0096] The adhesive strength and adhesive strength ratio (A2 / A1) described above can be adjusted, for example, by adjusting the content of the azobenzene derivative (B) in the adhesive layer 12 to a desired amount. The adhesive strength (A1) before UV irradiation in the adhesive strength ratio (A2 / A1) described above is the adhesive strength at 23°C in accordance with JIS Z 0237:2009, measured at a peel angle of 180° and a peel speed of 300 mm / min. The adhesive strength A2 after UV irradiation is measured at 23°C, with a wavelength of 365 nm and an illuminance of 200 mW / mm. 2 , light intensity 600mJ / mm 2 The adhesive strength is measured after irradiating with ultraviolet light for 3 seconds under the following conditions: a peel angle of 180°, a peel speed of 300 mm / min. Specifically, the adhesive strength can be measured in accordance with the method described in the Examples.

[0097] <Non-peeling substrate>

[0098] The material of the non-releasable substrate 10 is not particularly limited, and a suitable material can be selected taking into consideration the intended use, etc. The substrate 10 may or may not be optically transparent. However, when the pressure-sensitive adhesive sheet 1 is brought into contact with an adherend and then ultraviolet light is irradiated toward the pressure-sensitive adhesive layer 12 through the substrate 10 from the side of the pressure-sensitive adhesive sheet 1 opposite to the side that contacts the adherend (i.e., the side of the non-releasable substrate 10), the substrate 10 preferably has optical transparency (transparency). In this case, the substrate 10 needs to be transparent to active energy rays.

[0099] The non-releasable substrate 10 may be made of, for example, a substrate containing a resin (such as a resin-based substrate). Examples of such resins include one or more selected from the group consisting of polyester, polyolefin, acetyl cellulose butyrate, polyvinyl alcohol, ethylene-vinyl acetate copolymer, polystyrene, polycarbonate, polymethylpentene, polysulfone, polyether ether ketone, polyether sulfone, polyamide, polyetherimide, polyimide, fluorine-based resin, acrylic resin, norbornene-based resin, and cycloolefin-based resin. Examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Examples of polyolefins include polyethylene and polypropylene.

[0100] Among these, polyester and polyolefin are preferred as the resin constituting the substrate 10 from the viewpoints of transparency, economy, and adhesion to the photoactivatable pressure-sensitive adhesive layer 12, with polyethylene terephthalate and polypropylene being more preferred. The resin may be a petrochemical-derived resin using petroleum as the starting material, or a carbon-neutral resin derived from plants such as sugarcane. For example, polyester derived from biomass materials, polyolefin derived from biomass materials, etc. may also be used.

[0101] The substrate 10 may further contain additives. The type of additive is not particularly limited, and known additives can be selected in consideration of the intended use, etc. Examples of additives include antistatic agents, tackifiers, antioxidants, light stabilizers, softeners, fillers, and refractive index adjusters.

[0102] Although not shown, the layer structure of the non-releasable substrate 10 is not particularly limited and may be a single-layer structure consisting of only one layer, or a multilayer structure consisting of two or more layers. For example, the substrate 10 may have a two-layer structure including a first substrate layer and a second substrate layer formed on the surface of the first substrate layer. The first substrate layer may contain one of the resins described above, and the second substrate layer may contain a resin different from that of the first substrate layer. Alternatively, for example, the substrate 10 may include a substrate layer (sometimes referred to as a base layer, etc.) and an intermediate layer formed between the substrate layer and the photoactivatable pressure-sensitive adhesive layer. The intermediate layer may be a coating layer or the like that imparts a desired function.

[0103] The average thickness of the non-releasable substrate 10 is not particularly limited as long as it can be used as a pressure-sensitive adhesive sheet, but is preferably, for example, 2 to 200 μm. The lower limit is more preferably 12 μm or more, and even more preferably 25 μm or more. The upper limit is more preferably 190 μm or less, and even more preferably 125 μm or less.

[0104] The non-releasable substrate 10 may be subjected to a surface treatment such as corona treatment, for example, to improve adhesion to the photoactivatable pressure-sensitive adhesive layer. The method and conditions for the surface treatment are not particularly limited, and known methods and conditions can be adopted depending on the purpose.

[0105] <Light activated adhesive layer>

[0106] The photoactivatable pressure-sensitive adhesive layer 12 is a layer containing a photoactivatable pressure-sensitive adhesive composition, and is exemplified by a layer formed by molding the photoactivatable pressure-sensitive adhesive composition. When the photoactivatable pressure-sensitive adhesive composition contains an organic solvent, a coating film formed by applying the composition to the substrate 10 or the like may be used. The adhesive strength of the pressure-sensitive adhesive sheet 1 can be expressed or improved by irradiating the photoactivatable pressure-sensitive adhesive layer 12 with ultraviolet light.

[0107] Regarding optical properties, the photoactivatable pressure-sensitive adhesive layer 12 is thought to have a high haze value before UV irradiation because the (B) azobenzene derivative is not compatible with the (A) resin but exists as a solid. When the pressure-sensitive adhesive layer 12 is irradiated with UV light, the (B) azobenzene derivative, which exists as a solid in the (A) resin, undergoes a photoisomerization reaction, undergoes crystalline melting, and becomes more compatible with the (A) resin, resulting in a decrease in the haze value. Therefore, according to this embodiment, it is expected that the transparency of the photoactivatable pressure-sensitive adhesive layer can be improved by UV irradiation. For example, the photoactivatable pressure-sensitive adhesive layer 12 can be made to have a haze value that decreases at least upon UV irradiation. However, it is also possible to make the photoactivatable pressure-sensitive adhesive layer 12 have a high haze value before UV irradiation and a lower haze value after UV irradiation, which is a more preferable embodiment (however, the functions and effects of this embodiment are not limited to these).

[0108] The haze value of the photoactivatable pressure-sensitive adhesive layer 12 before UV irradiation is not particularly limited, but is preferably 20 to 100%. The lower limit of this haze value is more preferably 30% or more, even more preferably 40% or more, and even more preferably 45% or more. The upper limit of this haze value is more preferably 99.9% or less, even more preferably 99% or less, and even more preferably 98% or less.

[0109] The haze value of the photoactivatable pressure-sensitive adhesive layer 12 after UV irradiation is not particularly limited, but is preferably 0.001 to 30%. The upper limit of this haze value is more preferably 20% or less, even more preferably 15% or less, even more preferably 10% or less, even more preferably 5% or less, even more preferably 3% or less, and even more preferably 1% or less. The lower limit of this haze value may be 0.01% or more, 0.05% or more, or even 0.1% or more. By adjusting the haze value of the photoactivatable pressure-sensitive adhesive layer 12 to the above-mentioned range by UV irradiation, a suitable compatibility state (compatibility) between the (A) resin and the (B) azobenzene derivative in the pressure-sensitive adhesive sheet can be effectively maintained, and the desired adhesive strength can be effectively exhibited.

[0110] The haze value can be measured using a haze meter in accordance with JIS K 7136:2000. Specifically, it can be measured in accordance with the method described in the examples.

[0111] The thickness of the photoactivatable pressure-sensitive adhesive layer 12 is preferably 2 to 100 μm. The lower limit is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more. The upper limit of this thickness is preferably 80 μm or less, more preferably 70 μm or less, even more preferably 60 μm or less, and even more preferably 50 μm or less. When the thickness of the pressure-sensitive adhesive layer 12 is within the above range, the desired adhesive strength can be effectively exhibited after ultraviolet irradiation.

[0112] <Functional layer>

[0113] Furthermore, although not shown, the pressure-sensitive adhesive sheet 1 may have a functional layer between the non-releasable substrate 10 and the photoactivatable pressure-sensitive adhesive layer 12 and / or on the surface of the non-releasable substrate 10 opposite to the surface facing the photoactivatable pressure-sensitive adhesive layer 12. Examples of such functional layers include a buffer layer, a light-blocking layer, a reinforcing layer, a colored layer, a heat-conductive layer, an antistatic layer, etc. for the non-releasable substrate and the photoactivatable pressure-sensitive adhesive layer.

[0114] The method for producing the pressure-sensitive adhesive sheet 1 is not particularly limited as long as it can form the above-mentioned photoactivatable pressure-sensitive adhesive layer 12 on the surface of the substrate 10. One suitable example is a method for producing the pressure-sensitive adhesive sheet 1, in which a photoactivatable pressure-sensitive adhesive composition contains the above-mentioned solvent, and the method includes a step of applying the photoactivatable pressure-sensitive adhesive composition onto the surface of the substrate 10 to form the photoactivatable pressure-sensitive adhesive layer 12.

[0115] The coating method is not particularly limited, and any known method can be selected, such as bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating.

[0116] In the coating step, the solvent is removed to form the photoactivatable pressure-sensitive adhesive layer 12. For example, heating at a temperature at which the above-mentioned solvent can be volatilized can be used. Furthermore, if necessary, a predetermined curing period may be allowed after coating.

[0117] <Release liner>

[0118] Although not shown, the pressure-sensitive adhesive sheet 1 is also preferably a lined pressure-sensitive adhesive sheet 1 that has a release liner on at least a portion of the surface of the photoactivatable pressure-sensitive adhesive layer 12. The release liner is not particularly limited as long as it is a layer that can be peeled off from the photoactivatable pressure-sensitive adhesive layer. Specific examples of release liners include plastic films that have been treated with a release agent or the like. Specific examples of plastic films include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; and polyolefin films such as polypropylene and polyethylene. Specific examples of release agents include silicone-based release agents, fluorine-based release agents, and long-chain alkyl-based release agents.

[0119] The thickness of the release liner is not particularly limited, but is usually 20 μm to 250 μm.

[0120] The adhesive surface of the pressure-sensitive adhesive sheet 1 can be protected by providing a release liner on the adhesive surface until the adhesive surface of the photoactivatable pressure-sensitive adhesive layer 12 is attached to an adherend.

[0121] 3. How to use the adhesive sheet

[0122] FIG. 2 is a flow diagram showing a first method of using the pressure-sensitive adhesive sheet according to this embodiment.

[0123] A first method of using the adhesive sheet 1 according to this embodiment preferably includes the steps of irradiating ultraviolet light onto at least a portion of the surface of the photoactivatable adhesive layer 12 of the adhesive sheet 1 to develop or improve the adhesiveness of the photoactivatable adhesive layer 12, and attaching the photoactivatable adhesive layer 12 irradiated with ultraviolet light to the surface of an adherend.

[0124] <Step 1 (S11)>

[0125] It is preferable to irradiate ultraviolet light onto at least a portion of the surface of the photoactivatable pressure-sensitive adhesive layer 12 of the pressure-sensitive adhesive sheet 1. As a result, the azobenzene derivative (B) contained in the photoactivatable pressure-sensitive adhesive layer 12 at the portion irradiated with ultraviolet light is isomerized, thereby exhibiting or improving adhesive strength.

[0126] The ultraviolet light is preferably irradiated using a light source such as an ultraviolet LED (UV-LED) lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, a fusion H lamp, a metal halide lamp, or a xenon lamp. The amount of ultraviolet light irradiation can be appropriately selected in consideration of the material and thickness of the object to be irradiated. Usually, the irradiance of ultraviolet light is 50 to 1000 mW / cm. 2 The lower limit is preferably 100 mW / cm 2 More preferably, it is 200 mW / cm or more. 2 The upper limit is 600 mW / cm. 2 More preferably, it is 400 mW / cm or less. 2 The energy amount (light amount) of the ultraviolet light is more preferably 150 to 3000 mJ / cm.2 The lower limit is preferably 300 mJ / cm 2 More preferably, it is 600 mJ / cm or more. 2 The upper limit is 1800 mJ / cm. 2 More preferably, it is 1200 mJ / cm or less. 2 It is more preferable that:

[0127] <Step 2 (S12)>

[0128] It is preferable to apply the photoactivatable adhesive layer 12, whose adhesive strength has been developed or improved, to an adherend. After UV irradiation in step 1 (S11), the photoactivatable adhesive layer 12 is preferably applied to an adherend within 1 minute. The upper limit is more preferably within 30 seconds, and even more preferably within 10 seconds. The azobenzene derivative (B) contained in the photoactivatable adhesive layer 12 isomerizes again over time and reprecipitates in the resin (A). Therefore, after the adhesive strength has been developed or improved, the adhesive strength decreases over time. However, by applying the photoactivatable adhesive layer 12 to an adherend within the aforementioned time after UV irradiation, the desired adhesive strength can be obtained more effectively.

[0129] As an example, the explanation here is given using an adhesive sheet 1 having a non-peelable substrate 10, but it goes without saying that the first method of use described above can be used in a similar manner when using an adhesive sheet that does not have a non-peelable substrate 10.

[0130] Fig. 3 is a conceptual diagram illustrating an example of a first method of using the pressure-sensitive adhesive sheet according to the present embodiment. Note that Fig. 3 shows an example of the method of use described in the flow diagram of Fig. 2 above, and it goes without saying that the method of use according to this embodiment is not limited to this.

[0131] First, as shown in FIG. 3(1a), the pressure-sensitive adhesive sheet 1 can be placed with the photoactivatable pressure-sensitive adhesive layer 12 facing upward.

[0132] Next, as shown in Figure 3(1b), it is preferable to irradiate ultraviolet light u from a light source L toward at least a part of the surface A of the photoactivatable pressure-sensitive adhesive layer 12. The ultraviolet light irradiation conditions can be the same as those described above.

[0133] After ultraviolet irradiation, preferably within 1 minute, the adhesive sheet 1 can be attached to the adherend 5 with surface B of the non-peelable substrate 10 facing upward and surface A of the photoactivatable adhesive layer 12 facing downward, as shown in Figure 3 (1c).

[0134] The attached adhesive sheet 1 is adhered to an adherend 5, for example, as shown in FIG. 3(1d).

[0135] FIG. 4 is a flow diagram showing a second method of using the adhesive sheet 1 according to this embodiment.

[0136] A second method of using the adhesive sheet 1 according to this embodiment preferably includes the steps of contacting at least a portion of the surface of the photoactivatable adhesive layer 12 of the adhesive sheet 1 with an adherend, and irradiating with ultraviolet light at least a portion of the surface of the adhesive sheet 1 opposite the contact surface with the adherend, and / or at least a portion of the surface of the adherend opposite the contact surface with the adhesive sheet 1, thereby expressing or improving the adhesiveness of at least a portion of the contact surface of the photoactivatable adhesive layer 12, thereby attaching the adhesive sheet 1 to the adherend.

[0137] <Step 1 (S21)>

[0138] First, it is preferable to place the pressure-sensitive adhesive sheet 1 so that at least a portion of the surface of the photoactivatable pressure-sensitive adhesive layer 12 is in contact with the adherend. In the second method of use, the pressure-sensitive adhesive sheet 1 is brought into contact with the adherend before UV irradiation, making it even easier to position the contact area on the adherend.

[0139] <Step 2 (S22)>

[0140] Next, it is preferable to irradiate with ultraviolet light at least a portion of the surface of the adhesive sheet 1 opposite the surface that comes into contact with the adherend, and / or at least a portion of the surface of the adherend opposite the surface that comes into contact with the adhesive sheet 1. This effectively develops or improves the adhesiveness of at least a portion of the contact surface of the photoactivatable adhesive layer 12, allowing the adhesive sheet 1 to be attached to the adherend.

[0141] When the non-releasable substrate 10 of the pressure-sensitive adhesive sheet 1 is optically transparent, it is preferable to irradiate the pressure-sensitive adhesive sheet 1 with ultraviolet light from the surface side of the substrate 10. Furthermore, when the adherend is made of an optically transparent material, it is preferable to irradiate the pressure-sensitive adhesive sheet 1 with ultraviolet light from the adherend side, via the adherend, as necessary. Furthermore, it is also preferable, for example, to irradiate the pressure-sensitive adhesive sheet 1 with ultraviolet light from both the surface side of the substrate 10 and the surface side of the adherend, towards the photoactivatable pressure-sensitive adhesive layer 12. The ultraviolet light irradiation conditions can be, for example, the same as those described in the first method of use.

[0142] Although the explanation here is given taking as an example a case where a pressure-sensitive adhesive sheet 1 having a non-releasable substrate 10 is used, when a pressure-sensitive adhesive sheet not having a non-releasable substrate 10 is used, for example, in step 2 (S22), it is preferable to irradiate ultraviolet light from the surface of the photoactivatable pressure-sensitive adhesive layer 12 opposite to the surface that comes into contact with the adherend, and / or from the adherend side. Needless to say, other usage methods can also be used that are similar to the second usage method described above.

[0143] Fig. 5 is a conceptual diagram illustrating an example of a second method of using the pressure-sensitive adhesive sheet according to the present embodiment. Note that Fig. 5 shows an example of the method of use described in the flow diagram of Fig. 4 above, and it goes without saying that the method of use according to this embodiment is not limited to this.

[0144] First, as shown in FIG. 5(2a), an adhesive sheet 1 is prepared.

[0145] Next, as shown in FIG. 5(2b), the pressure-sensitive adhesive sheet 1 is placed on the adherend 5 so that the surface D of the photoactivatable pressure-sensitive adhesive layer 12 of the pressure-sensitive adhesive sheet 1 comes into contact with the adherend 5.

[0146] Next, as shown in Figure 5 (2c), ultraviolet light u is irradiated from a light source L toward the adhesive sheet 1 from the side of the surface C of the non-releasable substrate 10 of the adhesive sheet 1 placed on the adherend 5. The ultraviolet light irradiation conditions may be, for example, the same as those described in the first method of use.

[0147] The attached adhesive sheet 1 is adhered to an adherend 5, for example, as shown in FIG. 5(2d).

[0148] Based on the above, the photoactivatable pressure-sensitive adhesive composition according to the present embodiment can be suitably used as a pressure-sensitive adhesive. The adhesiveness induced by UV irradiation of a pressure-sensitive adhesive sheet including a photoactivatable pressure-sensitive adhesive layer containing this photoactivatable pressure-sensitive adhesive composition is maintained, for example, until the molecular shape of the azobenzene derivative returns to the shape it had before UV irradiation. Therefore, the pressure-sensitive adhesive sheet according to the present embodiment is easier to position on an adherend than adhesives that cure immediately. Furthermore, in one aspect of the pressure-sensitive adhesive sheet according to the present embodiment, the photoactivatable pressure-sensitive adhesive layer does not exhibit adhesiveness before UV irradiation. For example, the photoactivatable pressure-sensitive adhesive layer can be brought into contact with any desired contact position on an adherend, followed by UV irradiation and application. Therefore, the pressure-sensitive adhesive sheet according to the present embodiment can also exhibit the advantage of easier positioning on an adherend than pressure-sensitive adhesive sheets that do not require UV irradiation and have inherently high adhesive strength. Furthermore, it can exhibit the advantage of easy storage and handling. The adhesive strength of this pressure-sensitive adhesive sheet can be expressed or improved not only by UV irradiation, but also by heating above the glass transition temperature of the photoactivatable pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet according to this embodiment can be suitably used as a pressure-sensitive adhesive sheet for various purposes, including, for example, optical laminates, various electronic components, packaging, wrapping, protection, various surface protection and masking applications, label and seal applications, bundling applications, and applications for fixing items during transportation or movement.

[0149] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples. [Example]

[0150] The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples. Note that percentages and the like are based on mass unless otherwise specified.

[0151] Example 1

[0152] (Preparation of Photoactivatable Pressure-Sensitive Adhesive Composition)

[0153] (A) Acrylic resin (manufactured by Nippon Carbide Industries Co., Ltd., product name: Nissetsu PE121, solid content 34%, T g The components were mixed so as to obtain a photoactivatable pressure-sensitive adhesive composition in proportions of 93.3 mass% of (A) 1-phenyl-2-[4-(tetradecyloxy)phenyl]diazene (see formula (i) below), 4.7 mass% of (B) 1-phenyl-2-[4-(tetradecyloxy)phenyl]diazene (see formula (i) below), and 2.0 mass% of a tolylene diisocyanate crosslinking agent (manufactured by Toyo Ink Co., Ltd., trade name: BHS8515, solids content 37.5%).

[0154] 1-Phenyl-2-[4-(tetradecyloxy)phenyl]diazene was synthesized by the following method. In a 200 mL recovery flask, 5 g of 4-phenylazophenol and 3.49 g (1 eq) of potassium carbonate were dissolved in 25 mL of dimethylformamide (DMF). Furthermore, 10.5 mg (0.0025 eq) of potassium iodide was added at room temperature, and 8.81 g (10.3 mL, d = 0.859 g / mL, 1.5 eq) of 1-chlorotetradecane was added dropwise. The mixture was then reacted at 110 °C for 24 hours. The mixture was then allowed to cool to room temperature, and the reaction solution was poured into 100 mL of diethyl ether. The resulting precipitate was washed with 30 mL of water and 30 mL of hexane and air-dried to obtain 6.8 g of 1-phenyl-2-[4-(tetradecyloxy)phenyl]diazene represented by the following formula (i).

[0155] [ka]

[0156] (Preparation of adhesive sheet)

[0157] The obtained photoactivatable pressure-sensitive adhesive composition was applied to one side of a polyethylene terephthalate (PET) film, which was a non-releasable substrate 10, so that the film thickness after drying would be 30 μm. An applicator was used for application. The PET film with the photoactivatable pressure-sensitive adhesive composition applied thereto was then dried at a drying temperature of 100°C for 2 minutes, thereby forming a photoactivatable pressure-sensitive adhesive layer 12 on the surface of the substrate 10 and obtaining a pressure-sensitive adhesive sheet 1 (see FIG. 1).

[0158] <Example 2>

[0159] A photoactivatable pressure-sensitive adhesive composition was prepared in the same manner as in Example 1, except that the contents of the respective components were changed to (A) 89.1% by mass of acrylic resin, (B) 8.9% by mass of 1-phenyl-2-[4-(tetradecyloxy)phenyl]diazene, and (C) 2.0% by mass of tolylene diisocyanate crosslinking agent. Then, a pressure-sensitive adhesive sheet 1 was obtained in the same manner as in Example 1 using the obtained photoactivatable pressure-sensitive adhesive composition.

[0160] Example 3

[0161] A photoactivatable pressure-sensitive adhesive composition was prepared in the same manner as in Example 1, except that the contents of the respective components were changed to (A) 78.6% by mass of acrylic resin, (B) 1-phenyl-2-[4-(tetradecyloxy)phenyl]diazene, and (C) 1.7% by mass of tolylene diisocyanate crosslinking agent. Then, using the obtained photoactivatable pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet 1 was obtained in the same manner as in Example 1.

[0162] Example 4

[0163] (Preparation of Photoactivatable Pressure-Sensitive Adhesive Composition)

[0164] (A) Polyester resin (manufactured by Mitsubishi Chemical Corporation, trade name: Nichigo Polyester (registered trademark) SNT, solid content 60%, T g The components were mixed so as to obtain a photoactivatable pressure-sensitive adhesive composition in proportions of 89.9 mass% of (A) 1-phenyl-2-[4-(tetradecyloxy)phenyl]diazene (−15°C), 9.0 mass% of (B) 1-phenyl-2-[4-(tetradecyloxy)phenyl]diazene, and 1.1 mass% of (C) tolylene diisocyanate-based crosslinking agent (manufactured by Toyo Ink Co., Ltd., product name: BHS8515, solids content 37.5%).

[0165] (Formation of adhesive sheet)

[0166] The photoactivatable pressure-sensitive adhesive composition prepared above was applied to one side of a PET film, which is a non-releasable substrate 10, so that the film would have a dry thickness of 30 μm. An applicator was used for application. The film coated with the solution containing the photoactivatable pressure-sensitive adhesive composition was then dried at a drying temperature of 100°C for 2 minutes, thereby forming a photoactivatable pressure-sensitive adhesive layer 12 on the surface of the substrate 10 and obtaining a pressure-sensitive adhesive sheet 1.

[0167] <Example 5>

[0168] (Preparation of Photoactivatable Pressure-Sensitive Adhesive Composition)

[0169] A resin containing 27% by mass (3.6 g) of a styrene-isoprene-styrene (SIS) resin (manufactured by Zeon Corporation, product name: Quintac 3421), 23% by mass (3.1 g) of an SIS resin (manufactured by Zeon Corporation, product name: Quintac 3520), and 50% by mass (6.67 g) of a terpene resin (manufactured by Yasuhara Chemical Co., Ltd., product name: YS Resin PX1150) was prepared as the (A) resin. 90.9% by mass of the (A) resin and 9.1% by mass of (B) 1-phenyl-2-[4-(tetradecyloxy)phenyl]diazene were dissolved in 20 g of toluene to obtain a solution containing a photoactivatable pressure-sensitive adhesive composition.

[0170] (Preparation of adhesive sheet)

[0171] The obtained photoactivatable pressure-sensitive adhesive composition was applied to one side of a PET film, which was a non-releasable substrate 10, so that the film would have a dry thickness of 30 μm. An applicator was used for application. The film to which the photoactivatable pressure-sensitive adhesive composition was applied was then dried at a drying temperature of 100° C. for 2 minutes, thereby forming a photoactivatable pressure-sensitive adhesive layer 12 on the surface of the substrate 10 and obtaining a pressure-sensitive adhesive sheet 1 (see FIG. 1).

[0172] <Comparative Example 1>

[0173] Photoactivatable pressure-sensitive adhesive compositions were prepared in the same manner as in Example 1, except that the amounts of each component added were changed to those shown in Table 1. In Comparative Example 1, no azobenzene derivative was added. Then, a pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 using the obtained photoactivatable pressure-sensitive adhesive composition.

[0174] <Comparative Example 2>

[0175] The procedure of Example 1 was repeated, except that (B) 1-phenyl-2-[4-(tetradecyloxy)phenyl]diazene in Example 1 was changed to 4-phenylazophenol (see formula (ii) below). Then, a pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 using the obtained photoactivatable pressure-sensitive adhesive composition.

[0176] [ka]

[0177] <Comparative Example 3>

[0178] The same procedure as in Example 1 was repeated, except that (B) 1-phenyl-2-[4-(tetradecyloxy)phenyl]diazene in Example 1 was changed to 6-(4-phenylazophenoxy)-1-hexanol (see formula (iii) below).

[0179] [ka]

[0180] Table 1 shows the compositions of the examples and comparative examples. The compositions below are the content (% by mass) of each component relative to 100% by mass of the total solid content. For example, Example 1 contains components (A), (B), and (C) as solid content, and the content (% by mass) of each component is shown when the total of components (A), (B), and (C) is 100% by mass.

[0181] [Table 1]

[0182] <Evaluation method>

[0183] The physical properties of the pressure-sensitive adhesive sheets of each Example and Comparative Example were evaluated according to the methods described below.

[0184] (Adhesive strength before UV exposure)

[0185] First, the pressure-sensitive adhesive sheet 1 was cut into a width of 25 mm and a length of 150 mm to prepare a test piece. Then, the pressure-sensitive adhesive sheet 1 was placed on the soda-lime glass substrate so that the photoactivatable pressure-sensitive adhesive layer 12 of the test piece (pressure-sensitive adhesive sheet 1) was in contact with the soda-lime glass substrate.

[0186] A rubber roller (mass 2 kg) was then reciprocated once on the surface of the non-releasable substrate 10 of the pressure-sensitive adhesive sheet 1 to press the pressure-sensitive adhesive sheet 1 onto the surface of the soda-lime glass. The sheet was then left for 24 hours. The test piece was then peeled from the adherend using a tensile tester (manufactured by Orientec Co., Ltd., "Tensilon") in accordance with JIS Z 0237:2009 at a peel angle of 180° and a peel speed of 300 mm / min, and the adhesive strength was measured.

[0187] (Adhesive strength after UV exposure)

[0188] First, the pressure-sensitive adhesive sheet 1 was cut into a width of 25 mm and a length of 150 mm to prepare a test piece. Then, a high-pressure mercury lamp was used to illuminate the surface of the photoactivatable pressure-sensitive adhesive layer 12 of the test piece (pressure-sensitive adhesive sheet 1) at 23°C with a wavelength of 365 nm and an illuminance of 200 mW / mm. 2 , light intensity 600mJ / mm 2 The sample was irradiated with ultraviolet light for 3 seconds under the conditions.

[0189] Within 10 seconds after irradiation, the adhesive sheet 1 was placed on the soda-lime glass substrate so that the photoactivatable adhesive layer 12 of the test piece (adhesive sheet 1) was in contact with the soda-lime glass substrate. A rubber roller (mass: 2 kg) was then reciprocated once on the surface of the non-releasable substrate 10 of the adhesive sheet 1 to press the adhesive sheet 1 onto the surface of the soda-lime glass. The adhesive sheet was then left for 24 hours. The test piece was then peeled from the adherend using a tensile tester (manufactured by Orientec Co., Ltd., "Tensilon") in accordance with JIS Z 0237:2009 at a peel angle of 180° and a peel speed of 300 mm / min, and its adhesive strength was measured.

[0190] (Adhesive strength ratio before and after UV irradiation)

[0191] Based on the results of the above-mentioned adhesive strength measurements, the ratio (A2 / A1) of the adhesive strength A2 after ultraviolet irradiation to the adhesive strength A1 before ultraviolet irradiation was determined as the adhesive strength ratio before and after ultraviolet irradiation.

[0192] (Hayes)

[0193] Using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH-2000"), the haze value of the sample before and after UV irradiation was measured in accordance with JIS K 7136: 2000. The haze value of the sample after UV irradiation was measured within 10 seconds after UV irradiation.

[0194] Table 2 shows the evaluation results for each example and each comparative example.

[0195] [Table 2]

[0196] *) Ratio of adhesive strength A2 after UV irradiation to adhesive strength A1 before UV irradiation (A2 / A1)

[0197] From the above, it was at least confirmed that this example can develop or improve adhesive strength by ultraviolet irradiation. [Explanation of symbols]

[0198] 1...adhesive sheet, 5...Adherend, 10...Non-peeling substrate, 12...light-activated adhesive layer, L...Light source, u...ultraviolet light, A, B, C, D…Surface

Claims

1. (A) at least one resin selected from the group consisting of acrylic resins, polyester resins, and rubber resins; (B) an azobenzene derivative represented by formula (1), Light-activatable adhesive composition. 【Chemical 1】 (In the formula, R １ ~R １０ each independently represents a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen atom, an amino group, an acetyl group, a nitro group, or an unbranched or branched alkoxy group having 8 to 20 carbon atoms. １ ~R １０ At least one of is an unbranched or branched alkoxy group having 8 to 20 carbon atoms.

2. The azobenzene derivative (B) is 1-phenyl-2-[4-(tetradecyloxy)phenyl]diazene. The photoactivatable pressure-sensitive adhesive composition of claim 1 .

3. a mass ratio of the content of the azobenzene derivative (B) to the content of the resin (A) is 0.02 to 1; The photoactivatable pressure-sensitive adhesive composition according to claim 1 or 2.

4. A photoactivatable adhesive layer comprising the photoactivatable adhesive composition of claim 1. Adhesive sheet.

5. A photoactivatable adhesive layer is provided on at least a portion of one or both sides of a non-releasable substrate; No release liner is provided on the surface of the photoactivatable pressure-sensitive adhesive layer. It is linerless, The pressure-sensitive adhesive sheet according to claim 4.

6. The ratio (A2 / A1) of the adhesive strength A2 after ultraviolet irradiation to the adhesive strength A1 before ultraviolet irradiation is 10 or more. The pressure-sensitive adhesive sheet according to claim 4 or 5.

7. A roll comprising the pressure-sensitive adhesive sheet according to claim 4 or 5 wound around a core.

8. A step of irradiating ultraviolet light onto at least a part of the surface of the photoactivatable pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to claim 4 or 5 to develop or improve the adhesiveness of the photoactivatable pressure-sensitive adhesive layer; a step of attaching the photoactivatable pressure-sensitive adhesive layer irradiated with ultraviolet light to a surface of an adherend; and a method for using the adhesive sheet.

9. A step of contacting at least a portion of the surface of the photoactivatable pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to claim 4 or 5 with an adherend; and a step of irradiating ultraviolet light onto at least a portion of the surface of the adhesive sheet opposite the surface that comes into contact with the adherend, and / or onto at least a portion of the surface of the adherend opposite the surface that comes into contact with the adhesive sheet, thereby developing or improving the adhesiveness of at least a portion of the contact surface of the photoactivatable adhesive layer, thereby attaching the adhesive sheet to the adherend.

Images