Photocurable composition and its cured product, photomeltable resin composition, and adhesive set

Abstract

A photocurable composition is disclosed comprising a dithiol compound having a disulfide bond, a compound having two ethylenically unsaturated groups, a hydrogen extraction type photoradical generator, and an intramolecular cleavage type photoradical generator.

Description

Technology Field

[0001] The present disclosure relates to a photocurable composition and its cured product, a photomeltable resin composition, and an adhesive set. Background Technology

[0002] Photo-softening compositions that soften upon light irradiation are used for various purposes. For example, Patent Document 1 discloses an image forming device having a recording member having a photo-softening resin composed of a photo-softening resin composition. Prior art literature

[0003] Patent Document 1: Japanese Published Patent Application No. Hei 11-190883 The problem to be solved

[0004] General adhesives and temporary fixing materials typically control their properties through heating, such as by curing with heat for adhesion, softening with heat for peeling, or melting with thermoplastics for peeling. However, in the case of property control through heating, damage to the substrate and prolonged process time (takt time) have occurred. Regarding temporary fixing materials, since film products are common, it is difficult to temporarily fix substrates with steps, and peeling mechanisms often utilize curing shrinkage, foaming, or differences in coefficient of thermal expansion (CTE), which generally results in stress being applied to the substrate. It is believed that if a composition is cured and melted by light, the aforementioned problems are unlikely to occur.

[0005] One aspect of the present invention aims to provide a photocurable composition capable of forming a curable product that can be melted by light irradiation. means of solving the problem

[0006] One aspect of the present invention relates to a photocurable composition comprising a dithiol compound having a disulfide bond, a compound having two ethylenically unsaturated groups, a hydrogen extraction type photoradical generator, and an intramolecular cleavage type photoradical generator.

[0007] The photocurable composition can form a cured product that can be melted by light irradiation because it contains a dithiol compound having a disulfide bond, a compound having two ethylenically unsaturated groups, a hydrogen extraction type photoradical generator, and an intramolecular cleavage type photoradical generator.

[0008] The mechanism by which such effects are obtained is speculated to be, for example, as follows, but is not limited thereto. First, when a first light is irradiated onto a photocurable composition, a reaction (thiol-ene reaction) between a dithiol compound having a disulfide bond and a compound having two ethylenically unsaturated groups proceeds through a hydrogen extraction type photoradical generator. As a result, a cured product of the photocurable composition is formed, comprising the reaction product from the thiol-ene reaction and an intramolecular cleavage type photoradical generator. When a second light is irradiated onto the cured product of the photocurable composition, the photocurable can be softened. The mechanism by which the photocurable can be softened is not clear, but, for example, the following mechanism is conceived. However, it is not limited to these mechanisms. First, upon irradiation with the second light, the disulfide bonds in the photocurable are decomposed (cleaved), and thiyl radicals are generated. At this time, if an intramolecular cleavage type photoradical generator is present in the photocurable, the thiyl radical reacts with the photoradical generator, and the thiyl radical is capped by the photoradical generator. Through this, a mechanism is conceived in which the compound having a disulfide bond is reduced in molecular weight, and the photocurable is softened. As another mechanism, a photo-starting radical originating from an intramolecular cleavage type photoradical generator directly reacts with the disulfide bond, and the formation of a photo-starting radical-thioether bond and the generation of a thiyl radical occur, and the thiyl radical reacts with another photo-starting radical, and the compound having the disulfide bond itself is reduced in molecular weight, and the photocurable is softened. The first light includes light of a different wavelength from the second light. The first light may include light on the longer wavelength side than the second light. The first light may include light of a wavelength of 405 nm. The second light may include light with a wavelength of 365 nm. The reaction in which the disulfide bond is cleaved can be considered an irreversible reaction.

[0009] The compound having two ethylenically unsaturated groups may be at least one compound selected from the group consisting of a compound having two allyl groups or a compound having two vinyloxy groups.

[0010] The absorption coefficient of a hydrogen extraction type photoradical generator at a wavelength of 405 nm may be 7 or higher. The absorption coefficient of an intramolecular cleavage type photoradical generator at a wavelength of 405 nm may be 5 or lower, and the absorption coefficient at a wavelength of 365 nm may be 49 or higher.

[0011] The hydrogen extraction type photoradical generator may include at least one selected from the group consisting of fluorenone and benzyl. The intramolecular cleavage type photoradical generator may include one selected from the group consisting of 2,2-dimethoxy-1,2-diphenylethane-1-one and 2-hydroxy-2-methyl-1-phenylpropanone. The photocurable composition may be an adhesive.

[0012] Another aspect of the present invention relates to a cured product of the above-mentioned photocurable composition. Another aspect of the present invention relates to a photomeltable resin composition comprising a reaction product of a dithiol compound having a disulfide bond and a compound having two ethylenically unsaturated groups, and an intramolecular cleavage type photoradical generator.

[0013] Another aspect of the present invention relates to an adhesive set comprising a first component containing a dithiol compound having a disulfide bond and a second component containing a compound having two ethylenically unsaturated groups, wherein at least one of the first component and the second component further contains a hydrogen extraction type photoradical generator and at least one of the first component and the second component further contains an intramolecular cleavage type photoradical generator. Effects of the invention

[0014] According to one aspect of the present invention, a photocurable composition capable of forming a curable product that can be melted by light irradiation is provided. According to one aspect of the present invention, a cured product of the photocurable composition, a photomeltable resin composition using the photocurable composition, and an adhesive set are provided. Specific details for implementing the invention

[0015] Embodiments of the present invention will be described in detail below. However, the present invention is not limited to the following embodiments.

[0016] In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, provided that the intended function of the process is achieved. Additionally, numerical ranges indicated by "~" represent a range that includes the values ​​listed before and after "~" as the minimum and maximum values, respectively.

[0017] In addition, in this specification, the content of each component in the composition refers to the total amount of said multiple substances present in the composition, unless specifically explained otherwise, when multiple substances corresponding to each component exist in the composition. Also, unless specifically explained otherwise, the exemplary materials may be used alone or in combination of two or more types.

[0018] Furthermore, regarding numerical ranges described stepwise in this specification, the upper or lower limit of a numerical range in a given step may be substituted with the upper or lower limit of a numerical range in another step. Also, regarding numerical ranges described in this specification, the upper or lower limit of said numerical range may be substituted with the value shown in the example. "A or B" may include either A or B, or both.

[0019] [Photocurable composition]

[0020] A photocurable composition of one embodiment contains a dithiol compound having a disulfide bond (hereinafter referred to as component (A-1)), a compound having two ethylenically unsaturated groups (hereinafter referred to as component (A-2)), a hydrogen extraction type photoradical generator (hereinafter referred to as component (B-1)), and an intramolecular cleavage type photoradical generator (hereinafter referred to as component (B-2)).

[0021] (A-1) Component: Dithiol compound having a disulfide bond

[0022] (A-1) The component is a compound having a disulfide bond (-SS-) and also having two thiol groups (-SH). (A-1) The component may be a high molecular weight component of a polymer or oligomer. (A-1) The component may also be a compound comprising two thiol groups and a group (first linker) that includes a disulfide bond and connects the two thiol groups.

[0023] (A-1) The molecular weight or weight average molecular weight of the component may be 200 to 10000000, 200 to 3000000, 500 to 1000000, or 1000 to 10000. In addition, the weight average molecular weight is a polystyrene equivalent value using a calibration curve of standard polystyrene by gel permeation chromatography (GPC).

[0024] (A-1) The component has one or more (two or more) disulfide bonds within the molecule. The number of disulfide bonds in the component (A-1) may be, for example, 1 to 1000 or 4 to 50.

[0025] (A-1) The component may be a compound having a linear molecular chain and terminal groups, and having disulfide bonds within the molecular chain (e.g., a polymer or an oligomer). In this case, the terminal groups in the component (A-1) may be thiol groups. When the component (A-1) is such a compound, it becomes even easier to form a cured product having excellent photomeltability. The molecular chain in the component (A-1) may include disulfide bonds and polyether chains, or may consist of disulfide bonds and polyether chains.

[0026] (A-1) The component is, for example, Formula (1): HS-(ASS) n1 - It may be a compound represented by -A-SH (compound (1)) or a compound formed by chain extension of said compound. In the formula, A represents a polyether chain. Multiple A may be identical or different from each other. n1 represents an integer greater than or equal to 1. n1 may be, for example, greater than or equal to 1, or greater than or equal to 4, or less than or equal to 1000. If the (A-1) component is a compound represented by formula (1), -(ASS) n1 The group represented by -A- is the first linker. The compound obtained by chain extension of compound (1) may be, for example, a Michael adduct of compound (1) or a thiourethate of compound (1). The Michael adduct of compound (1) as component (A-1) is a compound having two thiol groups, which is a reactant of compound (1) and a compound having a group (e.g., acryloyl group) capable of reacting with a thiol group to form a bond by a Michael addition reaction (e.g., acrylate). The thiourethate of compound (1) as component (A-1) is a compound having two thiol groups, which is a reactant of diisocyanate and compound (1).

[0027] The polyether chain as A may be, for example, a polyoxyalkylene chain. The polyether chain as A may be, for example, -A 1 -OA2 -OA 3 It also becomes a contribution expressed as -. A 1 ~A 3 Each may independently be an alkylene group or an alkylene group having 1 to 2 carbon atoms (e.g., a methylene group, an ethylene group). Examples of polyether chains as A include -CH2CH2-O-CH2-O-CH2CH2- etc.

[0028] (A-1) As commercially available products of the component, examples include the Thiokol LP series (a disthiol having a disulfide bond, manufactured by Toray Fine Chemical Co., Ltd.). (A-1) The component may be used as a single type or in combination of two or more types. (A-1) The component may also be obtained by converting the reactive functional group of a compound having a reactive functional group (e.g., carboxyl group, hydroxyl group) and a disulfide bond at the terminal end into a thiol group. Examples of compounds having a reactive functional group and a disulfide bond at the terminal end include 3,3'-dithiodipropionic acid (manufactured by Tokyo Kasei High School Co., Ltd.), disthiodiethanol, cystamine, etc.

[0029] (A-1) The content of the component may be 50 mass% or more, 60 mass% or more, 70 mass% or more, 75 mass% or more, or 80 mass% or more, based on the total mass of the photocurable composition, or 95 mass% or less, 90 mass% or less, or 85 mass% or less.

[0030] (A-2) Component: A compound having two ethylenically unsaturated groups

[0031] (A-2) The component is a compound having two ethylenically unsaturated groups (C=C) within the molecule. (A-2) The component may also be a compound consisting of two ethylenically unsaturated groups and a group (second linker) connecting the two ethylenically unsaturated groups.

[0032] The second linker is a group capable of linking two ethylenically unsaturated groups, and may be, for example, a substituted or unsubstituted divalent hydrocarbon group. Examples of hydrocarbon groups include divalent aromatic groups such as phenylene groups and alkylene groups. The substituted hydrocarbon group may be a group consisting of the above hydrocarbon group and a group containing an oxygen atom. Examples of groups containing an oxygen atom include oxy groups (-O-) and ester groups (-OC(=O)-). The group containing an oxygen atom may be a polyoxyalkylene group such as a polyoxyethylene group.

[0033] (A-2) The component may be a compound having two groups selected from the group consisting of, for example, allyl groups (H2C=CH-CH2-), vinyloxy groups (H2C=CH-O-), and (meth)acryloyl groups. It may also include a compound having two groups selected from the group consisting of allyl groups and vinyloxy groups, for the sake of further improving photocurability and for the cured product to be more easily liquefied by light irradiation. (A-2) The component may include a compound having two allyl groups or a compound having two vinyloxy groups. For the sake of better curability, the compound having two ethylenically unsaturated groups may include, for example, a compound having two vinyloxy groups. The (meth)acryloyl group is a methacryloyl group or an acryloyl group.

[0034] (A-2) Examples of components include diallyl terephthalate, triethylene glycol divinyl ether, 1,4-cyclohexane dimethanol divinyl ether, diethylene glycol divinyl ether, 1,4-butanediol divinyl ether, etc. (A-2) Components may be used alone or in combination of two or more types.

[0035] (A-2) The content of the component may be 1.0 mass% or more, 2.0 mass% or more, 3.0 mass% or more, 3.5 mass% or more, or 4.0 mass% or more, based on the total mass of the photocurable composition, or 30 mass% or less, 20.0 mass% or less, 10.0 mass% or less, or 5.0 mass% or less.

[0036] The molar ratio of component (A-1) to component (A-2) (component (A-1) / component (A-2)) may be, for example, 0.8 to 1.2, or 0.9 to 1.1 or 0.98 to 1.02.

[0037] (B-1) Ingredient: Hydrogen extraction type photoradical generator

[0038] (B-1) Component is a compound that generates radicals by extracting hydrogen from other molecules upon irradiation with light. As (B-1) Component, a compound used as a hydrogen extraction type photoradical polymerization initiator may be used.

[0039] (B-1) Examples of components include hexaarylbisimidazole (HABI) compounds, benzophenone compounds, thioxantone compounds, fluorenone compounds, α-diketone compounds, etc. (B-1) components may be used alone or in combination of two or more types.

[0040] As HABI compounds, 2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole (e.g., 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole), 2,2'-bis(o-bromophenyl)-4,4',5,5'-tetraphenylbiimidazole, 2,2'-bis(o,p-dichlorophenyl)-4,4',5,5'-tetraphenylbiimidazole, 2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetra(m-methoxyphenyl)biimidazole, 2,2'-bis(o,o'-dichlorophenyl)-4,4',5,5'-tetraphenylbiimidazole, Examples include 2,2'-bis(o-nitrophenyl)-4,4',5,5'-tetraphenylbiimidazole, 2,2'-bis(o-methylphenyl)-4,4',5,5'-tetraphenylbiimidazole, etc.

[0041] Examples of benzophenone compounds include 4,4'-bis(dimethylamino)benzophenone and 4,4'-bis(diethylamino)benzophenone.

[0042] As thioxantone compounds, thioxantone, 2-isopropylthioxantone, 2-dodecylthioxantone, 2-cyclohexylthioxantone, 2,4-diethylthioxantone, 2,4-dimethylthioxantone, 1-phenoxythioxantone, 1-methoxycarbonylthioxantone, 2-ethoxycarbonylthioxantone, 3-(2-methoxyethoxycarbonyl)-thioxantone, 4-butoxycarbonylthioxantone, 3-butoxycarbonyl-7-methylthioxantone, 3,4-di-[2-(2-methoxyethoxy)-ethoxycarbonyl]-thioxantone, 2-chlorothioxantone, 1-ethoxycarbonyl-3-ethoxythioxantone, Examples include 1-ethoxycarbonyl-3-chlorothioxantone, 1-chloro-4-n-propoxythioxantone, 2-methyl-6-dimethoxymethyl-thioxantone, 2-methyl-6-(1,1-dimethoxybenzyl)-thioxantone, 6-ethoxycarbonyl-2-methoxy-thioxantone, 6-ethoxycarbonyl-2-methylthioxantone, 1-ethoxycarbonyl-3-(1-methyl-1-morphoethyl)-thioxantone, 2-morphomethylthioxantone, 2-methyl-6-morphomethylthioxantone, thioxantone-2-carboxylic acid polyethylene glycol ester, etc.

[0043] Examples of fluorenone compounds include 9-fluorenone, 3,4-benzo-9-fluorenone, 2-dimethylamino-9-fluorenone, 2-methoxy-9-fluorenone, 2-chloro-9-fluorenone, 2,7-dichloro-9-fluorenone, 2-bromo-9-fluorenone, 2,7-dibromo-9-fluorenone, 2-nitro-9-fluorenone, 2-acetoxy-9-fluorenone, etc.

[0044] Examples of α-diketone compounds include benzyl (also called diphenylethanedione or dibenzoyl).

[0045] (B-1) component may be a compound that absorbs light of wavelength 405 nm, for example. (B-1) component may be a compound whose absorption coefficient at wavelength 405 nm is greater than that of (B-2) component.

[0046] The absorption coefficient of component (B-1) at a wavelength of 405 nm may be 7 or higher. When the absorption coefficient of component (B-1) at a wavelength of 405 nm is within the above range, the effect of the present invention becomes even more pronounced.

[0047] In this specification, the absorption coefficients of Omnirad TPO (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide), Omnirad 754, and Omnirad MBF are values ​​measured in acetonitrile, and the absorption coefficients of other compounds are values ​​measured in methanol (unit: mL / g·cm).

[0048] Examples of (B-1) components having an absorption coefficient of 7 or higher at a wavelength of 405 nm include 2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole, 9-fluorenone, etc.

[0049] (B-1) The content of component (B-1) may be 0.5 parts by mass or more, 1.5 parts by mass or more, 3 parts by mass or more, or 4 parts by mass or more per 100 parts by mass of the photocurable composition. (B-1) The content of component (B-1) may be 20 parts by mass or less, 15 parts by mass or less, 10 parts by mass or less, or 7 parts by mass or less per 100 parts by mass of the photocurable composition.

[0050] (B-2) Component: Intramolecular cleavage photoradical generator

[0051] (B-2) The component is a compound that itself undergoes photolysis upon irradiation with light to generate two radicals. As the (B-2) component, a compound used as an intramolecular cleavage type photoradical polymerization initiator may be used.

[0052] Examples of intramolecular cleavage type photoradical generators include benzyl ketal-based photoradical generators, α-aminoalkylphenone-based photoradical generators, α-hydroxyalkylphenone-based photoradical generators, α-hydroxyacetophenone-based photoradical generators, and acylphosphine oxide-based photoradical generators. (B-2) The component may be used as a single type or in combination of two or more types.

[0053] Examples of benzyl ketal-based photoradical generators include 2,2-dimethoxy-1,2-diphenylethane-1-one (Omnirad 651).

[0054] Examples of α-aminoalkylphenone photoradical generators include 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (Omnirad 369), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (Omnirad 907), and 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butanone-1-one (Omnirad 379EG).

[0055] Examples of α-hydroxyalkylphenone-based photoradical generators include 1-hydroxy-cyclohexyl-phenyl-ketone (Omnirad 184).

[0056] Examples of α-hydroxyacetophenone-based photoradical generators include 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl-propan-1-one (Omnirad 127), 2-hydroxy-2-methyl-1-phenyl-propan-1-one (Omnirad 1173), etc.

[0057] Examples of acylphosphine oxide-based photoradical generators include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (Omnirad TPO H) and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Omnirad 819).

[0058] (B-2) Component may be a compound that absorbs light of wavelength 365 nm and does not substantially absorb light of wavelength 405 nm, or has an absorption coefficient of wavelength 405 nm smaller than that of component (B-1). The absorption coefficient of component (B-2) at wavelength 365 nm may be 49 or higher. In this specification, "does not substantially absorb light of wavelength 405 nm" means that the absorption coefficient at wavelength 405 nm is 5 or lower. Component (B-2) may be a compound that has an absorption coefficient of wavelength 365 nm of 49 or higher and an absorption coefficient at wavelength 405 nm of 5 or lower. When the absorption coefficients at wavelength 405 nm and wavelength 365 nm of component (B-2) are within the above ranges, the effects of the present invention become even more pronounced.

[0059] Examples of (B-2) components that have an absorption coefficient of 49 or higher at a wavelength of 365 nm and an absorption coefficient of 5 or lower at a wavelength of 405 nm include, for example, Omnirad 651, Omnirad 1173, Omnirad 184, etc.

[0060] (B-2) The content of the component may be 1 part by mass or more, 3 parts by mass or more, 5 parts by mass or more, 10 parts by mass or more, 15 parts by mass or more, or 25 parts by mass or more, per 100 parts by mass of the photocurable composition. (B-2) The content of the component may be 50 parts by mass or less, 40 parts by mass or less, 35 parts by mass or less, or 30 parts by mass or less, per 100 parts by mass of the photocurable composition.

[0061] The combination of component (B-1) and component (B-2) may be a combination of fluorenone and 2,2-dimethoxy-1,2-diphenylethane-1-one, a combination of benzyl and 2-hydroxy-2-methyl-1-phenylpropanone, a combination of benzyl and 2,2-dimethoxy-1,2-diphenylethane-1-one, or a combination of benzyl and 1-hydroxy-cyclohexyl-phenyl-ketone.

[0062] The photocurable composition may comprise at least one hydrogen extraction type photoradical generator selected from the group consisting of fluorenone and benzyl, and may also comprise one intramolecular cleavage type photoradical generator selected from the group consisting of 2,2-dimethoxy-1,2-diphenylethane-1-one and 2-hydroxy-2-methyl-1-phenylpropanone.

[0063] The photocurable composition may further include other components other than component (A-1), component (A-2), component (B-1), and component (B-2). Examples of other components include additives such as plasticizers, tackifiers and other tackifiers, antioxidants, leuco dyes, sensitizers, coupling agents and other adhesion enhancers, polymerization inhibitors, light stabilizers, defoaming agents, fillers, chain transfer agents, thixotropy imparters, flame retardants, release agents, surfactants, lubricants, and antistatic agents. Known additives may be used. The total content of other components may be 0 to 95 mass%, 0.01 to 50 mass%, or 0.1 to 10 mass% based on the total amount of the photocurable composition.

[0064] The photocurable composition may be used as a varnish of a photocurable composition diluted with a solvent. As a solvent component, for example, aromatic hydrocarbons such as toluene, xylene, mesitylene, cumene, p-cymene, etc.; aliphatic hydrocarbons such as hexane, heptane, etc.; cyclic alkanes such as methylcyclohexane, etc.; cyclic ethers such as tetrahydrofuran, 1,4-dioxane, etc.; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone, etc.; esters such as methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, γ-butyrolactone, etc.; carbonate esters such as ethylene carbonate, propylene carbonate, etc. Examples include amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone (NMP). (E) The component may be used as a single type or in combination of two or more types. The content of solids in the varnish, that is, the total content of substances other than solvents in the varnish, may be 10 to 95 mass%, or 15 to 70 mass%, or 20 to 50 mass% based on the total mass of the varnish.

[0065] A photocurable composition can be prepared by a method comprising, for example, a process of mixing or kneading component (A-1), component (A-2), component (B-1), component (B-2), and component (A-3), and an additional component as needed. Mixing and kneading can be performed by appropriately combining a dispersion device such as a conventional stirrer, a blaster, a three-roll mill, a ball mill, or a bead mill.

[0066] The photocurable composition can form a cured product upon light irradiation. By irradiating the photocurable composition with light, a thiol-ene reaction of component (A-1) and component (A-2) proceeds. The thiol-ene reaction proceeds starting from the point where a hydrogen-extracting photoradical generator extracts hydrogen from the thiol group in component (A-1) upon light irradiation. The reaction product of component (A-1) and component (A-2) includes, for example, a compound represented by the following formula. The cured product contains the reaction product of component (A-1) and component (A-2) and an intramolecular cleavage-type photoradical generator.

[0067] [Chemical Formula 1]

[0068]

[0069] In the expression, X represents the first connector and Y represents the second connector. m represents an integer greater than or equal to 1. m may be, for example, 25 or greater, or 50 or greater, or 100 or greater, or 250 or greater.

[0070] For example, a cured product of a photocurable composition can be formed by irradiating a photocurable composition with first light comprising light of a wavelength of 405 nm. The exposure amount of the first light is, for example, 20,000 mJ / cm² 2 The above may be sufficient. In this specification, the amount of light exposure refers to the product of the illuminance and the irradiation time (seconds). The irradiation of light may be performed directly on the object to be irradiated, or through a glass or the like. The light source used for light irradiation is not particularly limited and may be, for example, an LED lamp, a mercury lamp (low pressure, high pressure, ultra-high pressure, etc.), a metal halide lamp, an excimer lamp, a xenon lamp, etc., and preferably, an LED lamp, a mercury lamp, a metal halide lamp, etc.

[0071] The cured product of the photocurable composition can be formed into various shapes. For example, a cured product formed in the form of a film can be used as a resin film. A cured product formed in the form of a block can be used as a resin block. The method of forming the film-shaped or block-shaped cured product is not particularly limited, and known methods may be applied.

[0072] The storage modulus of the cured product of the photocurable composition at 25°C may be 5,000 Pa or more, 7,000 Pa or more, or 100,000 Pa or more. The storage modulus of the cured product of the photocurable composition at 25°C is not particularly limited, but may be, for example, 1,000 MPa or less. In this specification, the storage modulus at 25°C refers to a value measured by the method described in the examples.

[0073] The cured material has the property of photomelting upon light irradiation. For example, the cured material can be melted by irradiating it with a second light containing light of a wavelength of 365 nm. The exposure dose of the second light is, for example, 5000 mJ / cm² 2 The above may be sufficient. Light irradiation may be performed directly on the object to be irradiated, or through a glass or the like. The light source, etc. used for light irradiation may be the same as above.

[0074] When irradiated with light, an intramolecular cleavage type photoradical generator cleaves the disulfide bonds (-SS-) in the reaction products of component (A-1) and component (A-2). As a result, the reaction products of component (A-1) and component (A-2) are reduced in molecular weight and become a liquid (liquid phase). The cured product of the above-described photocurable composition may also be referred to as a photomeltable composition in that it melts upon irradiation with light. The photomeltable composition contains the reaction products of component (A-1) and component (A-2) and an intramolecular cleavage type photoradical generator.

[0075] The storage modulus of the cured product of the photocurable composition at 25°C after light irradiation may be 100 Pa or less, 10 Pa or less, or 8.5 Pa or less. The storage modulus of the cured product of the photocurable composition at 25°C is not particularly limited, but, for example, may be greater than 0 MPa.

[0076] The photocurable composition of the present embodiment can be used for purposes such as adhesives, temporary fixing materials, photoresists, resins for 3D printers, resins for molding materials, etc.

[0077] The adhesive set of the present embodiment comprises a first component containing a dithiol compound having a disulfide bond (component (A-1)) and a second component containing a compound having two ethylenically unsaturated groups (component (A-2)). At least one of the first component and the second component further contains a hydrogen extraction type photoradical generator (component (B-1)), and at least one of the first component and the second component further contains an intramolecular cleavage type photoradical generator (component (B-2)). At least one of the first component and the second component may further contain other components as described above.

[0078] When mixing the first component and the second component, the equivalent ratio (molar ratio) of component (A-1) to component (A-2) may be, for example, 0.8 to 1.2.

[0079] The adhesive set of the present embodiment can prepare an adhesive composition by mixing the first component and the second component. The temperature and time for mixing the first component and the second component may be, for example, 10 to 35°C and 0.1 to 60 minutes.

[0080] Methods for mixing the first component and the second component include, for example, mixing manually using a spatula, mixing by hand using a conventional caulking gun, and mixing using a mechanical rotary mixer, static mixer, etc., in combination with a throttle valve and a pump capable of quantitative transfer of raw materials (e.g., a gear pump, a plunger pump, etc.).

[0081] The prepared adhesive composition can form a cured product of the adhesive composition by light irradiation and can act as an adhesive layer that bonds substrates together. For example, the adhesive composition can be cured by irradiating light including light with a wavelength of 405 nm.

[0082] An adhesive composition comprising a first component and a second component has adhesive properties, and a cured product of the adhesive composition has photomelting properties upon light irradiation. Therefore, the adhesive composition can also be used as an adhesive having repair properties.

[0083] An adhesive of one embodiment comprises a first substrate, a second substrate, and an adhesive layer that bonds the first substrate and the second substrate to each other. The adhesive layer contains a cured product of a photocurable composition.

[0084] Examples of the first and second adherends include plastics such as polyolefin resin, polyamide resin, ABS, PC, PET, PPS, acrylic resin, wood, rubber, or inorganic materials such as steel, stainless steel, aluminum, copper, nickel, chromium or their alloys, glass, silicon wafer, etc.

[0085] The adhesive comprises a process of bonding a first substrate and a second substrate by interposing a photocurable composition. The curing conditions, etc., may be the same as those above.

[0086] A method for separating adherents according to one embodiment comprises a process of separating a first adherent and a second adherent by irradiating light onto an adhesive layer of an adhesive. Since the adhesive layer contains a cured product of the photocurable composition described above, the cured product of the photocurable composition can be melted by irradiating light, thereby allowing the adherents to be easily separated from each other.

[0087] In the method for separating the adherend, the type of light, light source, etc. when irradiating light may be the same as above.

[0088] Examples

[0089] The present invention will be explained in more detail below with reference to examples. However, the present invention is not limited to these examples.

[0090] The compounds shown below were prepared.

[0091] (A-1) Ingredient:

[0092] · Thiokol LP-55 (Dithiol compound having a disulfide bond, manufactured by Toray Fine Chemicals, Inc.)

[0093] (A-2) Ingredients:

[0094] · Diallyl terephthalate (Allyl number: 2, manufactured by Tokyo Kasei High School Co., Ltd.)

[0095] · Triethylene glycol divinyl ether (Vinyl ether number: 2, manufactured by Tokyo Kasei High School Co., Ltd.)

[0096] (B-1) Ingredient:

[0097] · Fluorenumon (manufactured by Fujifilm Wako Junyaku Co., Ltd.)

[0098] · Benzyl (manufactured by Fujifilm Wako Junyaku Co., Ltd.)

[0099] (B-2) Ingredients:

[0100] ·2,2-Dimethoxy-1,2-Diphenylethane-1-one (IGM Resins BV, trade name Omnirad 651)

[0101] · 2-hydroxy-2-methyl-1-phenylpropanone (IGM Resins BV, trade name Omnirad 1173)

[0102] [Preparation of Photopolymerizable Compounds]

[0103] Ingredients (A-1), (A-2), (B-1), and (B-2) listed in Table 1 in their respective amounts (unit: parts by mass) were added to a 125ml ointment container, and mixed at 2000 rpm for 3 minutes using a self-rotating stirrer (Shinky Co., Ltd., trade name: Awatori Rentaro ARE-310). Subsequently, each ointment container was heated at 90°C for 1 hour using a box-type dryer, and then mixed again at 2000 rpm for 3 minutes using a self-rotating stirrer to obtain a photocurable composition.

[0104] Using a viscoelasticity measuring device (manufactured by TA Instruments, product name: DHR-2), the change in storage modulus at 25°C with respect to irradiation time was measured by irradiating an evaluation sample with ultraviolet light from a light-transmitting bottom surface. For irradiation, LED lamps (manufactured by Panasonic Device SUNX Co., Ltd., product names: AicureUJ30 / ANUJ6186 and ANUJ6189) were used to expose the sample at the wavelength and exposure amount shown in Table 1 as the first wavelength. Subsequently, the sample was exposed at the wavelength and exposure amount shown in Table 1 as the second wavelength. Table 1 shows the results of the storage modulus at 25°C before irradiation, after irradiation at the first wavelength, and after irradiation at the second wavelength.

[0105] [Table 1]

[0106]

[0107] As shown in Table 1, it was found that a photocurable composition containing a dithiol compound having a disulfide bond, a compound having two ethylenically unsaturated groups, a hydrogen extraction type photoradical generator, and an intramolecular cleavage type photoradical generator can form a curable product that can be melted by light irradiation.

Claims

Claim 1 A photocurable composition comprising a dithiol compound having a disulfide bond, a compound having two ethylenically unsaturated groups, a hydrogen extraction type photoradical generator, and an intramolecular cleavage type photoradical generator. Claim 2 A photocurable composition according to claim 1, wherein the compound having two ethylenically unsaturated groups is a compound having two allyl groups or a compound having two vinyloxy groups. Claim 3 A photocurable composition according to claim 1 or claim 2, wherein the absorption coefficient of the hydrogen extraction type photoradical generator at a wavelength of 405 nm is 7 or higher, the absorption coefficient of the intramolecular cleavage type photoradical generator at a wavelength of 405 nm is 5 or lower, and the absorption coefficient at a wavelength of 365 nm is 49 or higher. Claim 4 A photocurable composition according to claim 1 or claim 2, wherein the hydrogen extraction type photoradical generator comprises at least one selected from the group consisting of fluorenone and benzyl. Claim 5 A photocurable composition according to claim 1 or claim 2, wherein the intramolecular cleavage type photoradical generator comprises one selected from the group consisting of 2,2-dimethoxy-1,2-diphenylethane-1-one and 2-hydroxy-2-methyl-1-phenylpropanone. Claim 6 A photocurable composition used in an adhesive, according to claim 1 or claim 2. Claim 7 A cured product of the photocurable composition described in claim 1 or claim 2. Claim 8 An adhesive set comprising a first component containing a dithiol compound having a disulfide bond, and a second component containing a compound having two ethylenically unsaturated groups, wherein at least one of the first component and the second component further contains a hydrogen extraction type photoradical generator, and at least one of the first component and the second component further contains an intramolecular cleavage type photoradical generator. Claim 9 delete

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