Photocurable composition and cured product thereof, photo-dissolvable resin composition, and adhesive set

Abstract

The present invention discloses a photocurable composition which contains a dithiol compound that has a disulfide bond, a compound that has two ethylenically unsaturated groups, a hydrogen abstraction type photoradical generator, and an intramolecular cleavage type photoradical generator.

Description

Technical Field

[0001] The present disclosure relates to a photocurable composition and a cured product thereof, a photo-melting resin composition, and an adhesive set.

Background Art

[0002] Photo-softening compositions that soften upon light irradiation are used in various applications. For example, Patent Document 1 discloses an image forming apparatus including a recording member having a photo-softening resin made of a photo-softening resin composition.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In general, for general adhesives and temporary fixing materials, characteristic control by heating is common, such as curing by heat for adhesion, softening by heat for peeling, or melting by heat plasticity for peeling. However, in characteristic control by heating, there are cases where damage is caused to the base material and cases where the process working time (tact time) becomes long. For temporary fixing materials, since there are generally many film products, it is difficult to temporarily fix a base material with steps, etc., and the peeling mechanism also often uses mechanisms such as curing shrinkage, foaming, and difference in thermal expansion coefficient (CTE), and it is common for stress to be applied to the base material. It is considered that such disadvantages are less likely to occur in a composition that cures with light and melts with light.

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

Means for Solving the Problems

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

[0007] Since the photocurable composition contains a dithiol compound having a disulfide bond, a compound having two ethylenically unsaturated groups, a hydrogen abstraction type photo radical generator, and an intramolecular cleavage type photo radical generator, a cured product that can be melted by light irradiation can be formed.

[0008] The mechanism by which such an effect is obtained is presumed as follows, for example, but is not limited thereto. First, when the photocurable composition is irradiated with the first light, the reaction (thiol-ene reaction) between the dithiol compound having a disulfide bond and the compound having two ethylenically unsaturated groups proceeds by the hydrogen abstraction type photo radical generator. As a result, a cured product of the photocurable composition containing a reaction product by the thiol-ene reaction and an intramolecular cleavage type photo radical generator is formed. When the cured product of the photocurable composition is irradiated with the second light, the photocured product can be softened. The mechanism by which the photocured product can be softened is not clear, but for example, the following mechanisms can be considered. However, it is not limited to these mechanisms. First, the disulfide bond in the photocured product is decomposed (cleaved) by the irradiation with the second light, and a thioyl radical is generated. At this time, if an intramolecular cleavage type photo radical generator is present in the photocured product, the thioyl radical reacts with the photo radical generator, and the thioyl radical is capped by the photo radical generator. As a result, a mechanism is considered in which the compound having a disulfide bond is reduced in molecular weight and the photocured product is softened. As another mechanism, a photoinduced radical derived from the intramolecular cleavage type photo radical generator directly reacts with the disulfide bond, formation of a photoinduced radical-thioether bond and generation of a thioyl radical occur, the thioyl radical reacts with another photoinduced radical, and a mechanism is also considered in which the compound itself having a disulfide bond is reduced in molecular weight and the photocured product is softened. The first light includes light having a wavelength different from that of the second light. The first light may include light on the longer wavelength side than the second light. The first light may include light having a wavelength of 405 nm. The second light may include light having a wavelength of 365 nm. It can be said that the reaction in which the disulfide bond is cleaved is 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 extinction coefficient at a wavelength of 405 nm of the hydrogen abstraction type photo radical generator may be 7 or more. The extinction coefficient at a wavelength of 405 nm of the intramolecular cleavage type photo radical generator may be 5 or less, and the extinction coefficient at a wavelength of 365 nm may be 49 or more.

[0011] The hydrogen abstraction type photo radical generator may contain at least one selected from the group consisting of fluorenone and benzyl. The intramolecular cleavage type photo radical generator may contain 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 photocurable composition. Another aspect of the present invention relates to a photo-melting resin composition containing a reaction product of a dithiol compound having a disulfide bond and a compound having two ethylenically unsaturated groups, and an intramolecular cleavage type photo radical generator.

[0013] Another aspect of the present invention relates to an adhesive set including 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 abstraction type photo radical generator, and at least one of the first component and the second component further contains an intramolecular cleavage type photo radical generator.

Advantages of the Invention

[0014] According to one aspect of the present invention, there is provided a photocurable composition capable of forming a cured product that can be melted by light irradiation. According to one aspect of the present invention, there are provided a cured product of the above photocurable composition, a photo-melting resin composition using the above photocurable composition, and an adhesive set.

Embodiments for Carrying Out the Invention

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

[0016] In this specification, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps as long as the intended function of the step is achieved. Also, the numerical range indicated using "~" represents a range that includes the numerical values described before and after "~" as the minimum value and the maximum value, respectively.

[0017] Also, in this specification, the content of each component in the composition, when there are a plurality of substances corresponding to each component in the composition, means the total amount of the plurality of substances present in the composition unless otherwise specified. Also, the exemplary materials may be used alone or in combination of two or more unless otherwise specified.

[0018] Also, in the numerical ranges described step by step in this specification, the upper limit value or the lower limit value of the numerical range at a certain step may be replaced with the upper limit value or the lower limit value of the numerical range at another step. Also, in the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. "A or B" means that either A or B may be included, or both may be included.

[0019] [Photocurable Composition] A photocurable composition according to one embodiment contains a dithiol compound having a disulfide bond (hereinafter sometimes referred to as component (A-1)), a compound having two ethylenically unsaturated groups (hereinafter sometimes referred to as component (A-2)), a hydrogen abstraction type photo radical generator (hereinafter sometimes referred to as component (B-1)), and an intramolecular cleavage type photo radical generator (hereinafter sometimes referred to as component (B-2)).

[0020] Component (A-1): A dithiol compound having a disulfide bond (Component (A-1) is a compound having a disulfide bond (-S-S-) and two thiol groups (-SH). Component (A-1) may be a high molecular weight component of a polymer or oligomer. Component (A-1) can also be said to be a compound composed of two thiol groups, a disulfide bond, and a group (first linking group) that links the two thiol groups.)

[0021] (The molecular weight or weight average molecular weight of component (A-1) may be 200 to 10,000,000, 200 to 3,000,000, 500 to 1,000,000, or 1,000 to 10,000. The weight average molecular weight is a polystyrene conversion value using a calibration curve with standard polystyrene by gel permeation chromatography (GPC).)

[0022] (Component (A-1) has one or more (two or more) disulfide bonds in the molecule. The number of disulfide bonds in component (A-1) may be, for example, 1 to 1,000, or 4 to 50.)

[0023] (Component (A-1) may be a compound (e.g., a polymer or oligomer) having a linear molecular chain and terminal groups, and having a disulfide bond in the molecular chain. In this case, the terminal group in component (A-1) may be a thiol group. When component (A-1) is such a compound, it becomes easier to form a cured product having excellent photo-melting properties. The molecular chain in component (A-1) may contain a disulfide bond and a polyether chain, and may consist of a disulfide bond and a polyether chain.)

[0024] (Component (A-1) may be, for example, a compound represented by formula (1): HS-(A-S-S) n1 -A-SH (compound (1)) or a compound obtained by chain-extending the compound. In the formula, A represents a polyether chain. A plurality of A's may be the same as or different from each other. n1 represents an integer of 1 or more. n1 may be, for example, 1 or more, or 4 or more, and may also be 1,000 or less. When component (A-1) is a compound represented by formula (1), -(A-S-S) n1The group represented by -A- is the first linking group. The compound obtained by chain-extending compound (1) may be, for example, a Michael adduct of compound (1) or a thiourethanized product of compound (1). The Michael adduct of compound (1) as component (A-1) is a reaction product of a compound (e.g., a diacrylate) having a group (e.g., an acryloyl group) capable of reacting with a thiol group to form a bond by a Michael addition reaction and compound (1), and is a compound having two thiol groups. The thiourethanized product of compound (1) as component (A-1) is a reaction product of a diisocyanate and compound (1), and is a compound having two thiol groups.

[0025] The polyether chain as A may be, for example, a polyoxyalkylene chain. The polyether chain as A may be, for example, -A 1 -O-A 2 -O-A 3 a group represented by -. A 1 ~A 3 may each independently be an alkylene group, and may be an alkylene group having 1 to 2 carbon atoms (e.g., a methylene group, an ethylene group). Examples of the polyether chain as A include -CH2CH2-O-CH2-O-CH2CH2- and the like.

[0026] Examples of commercially available products of component (A-1) include the Thiolcol LP series (dithiol having a disulfide bond, manufactured by Toray Fine Chemical Co., Ltd.) and the like. Component (A-1) may be used alone or in combination of two or more. Component (A-1) can also be obtained by converting the reactive functional group of a compound having a reactive functional group (e.g., a carboxy group, a hydroxy group) and a disulfide bond at the terminal into a thiol group. Examples of the compound having a reactive functional group and a disulfide bond at the terminal include 3,3'-dithiodipropionic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), dithiodiethanol, cystamine, and the like.

[0027] The content of the component (A-1) may be 50% by mass or more, 60% by mass or more, 70% by mass or more, 75% by mass or more, or 80% by mass or more, and may be 95% by mass or less, 90% by mass or less, or 85% by mass or less, based on the total mass of the photocurable composition.

[0028] Component (A-2): A compound having two ethylenically unsaturated groups Component (A-2) is a compound having two ethylenically unsaturated groups (C=C) in the molecule. Component (A-2) can also be said to be a compound composed of two ethylenically unsaturated groups and a group (second linking group) that links the two ethylenically unsaturated groups.

[0029] The second linking group is a group capable of linking two ethylenically unsaturated groups, and may be, for example, a substituted or unsubstituted divalent hydrocarbon group. Examples of the hydrocarbon group include divalent aromatic groups such as a phenylene group and an alkylene group. The substituted hydrocarbon group may be a group composed of the above hydrocarbon group and a group containing an oxygen atom. Examples of the group containing an oxygen atom include an oxy group (-O-), an ester group (-O-C(=O)-), etc. The group containing an oxygen atom may be a polyoxyalkylene group such as a polyoxyethylene group.

[0030] Component (A-2) may be, for example, a compound having two groups selected from the group consisting of an allyl group (H2C=CH-CH2-), a vinyloxy group (H2C=CH-O-), and a (meth)acryloyl group. From the viewpoint of further improving the photocurability and the viewpoint that the cured product becomes more easily liquefied by light irradiation, etc., it may contain a compound having two groups selected from the group consisting of an allyl group and a vinyloxy group. Component (A-2) may contain a compound having two allyl groups or a compound having two vinyloxy groups. From the viewpoint of further excellent curability, the compound having two ethylenically unsaturated groups may contain, for example, a compound having two vinyloxy groups. The (meth)acryloyl group is a methacryloyl group or an acryloyl group.

[0031] Examples of the component (A-2) include diallyl terephthalate, triethylene glycol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, diethylene glycol divinyl ether, 1,4-butanediol divinyl ether, etc. The component (A-2) may be used alone or in combination of two or more kinds.

[0032] The content of the component (A-2) may be 1.0% by mass or more, 2.0% by mass or more, 3.0% by mass or more, 3.5% by mass or more, or 4.0% by mass or more, and may be 30% by mass or less, 20.0% by mass or less, 10.0% by mass or less, or 5.0% by mass or less, based on the total mass of the photocurable composition.

[0033] The molar ratio of the component (A-1) to the component (A-2) ((A-1) component / (A-2) component) may be, for example, 0.8 to 1.2, or 0.9 to 1.1 or 0.98 to 1.02.

[0034] (B-1) component: Hydrogen abstraction type photo radical generator The component (B-1) is a compound that generates radicals by abstracting hydrogen from other molecules upon irradiation with light. As the component (B-1), compounds used as hydrogen abstraction type photo radical polymerization initiators can be used.

[0035] Examples of the component (B-1) include hexaaryl bisimidazole (HABI) compounds, benzophenone compounds, thioxanthone compounds, fluorenone compounds, α-diketone compounds, etc. The component (B-1) may be used alone or in combination of two or more kinds.

[0036] Examples of HABI compounds include 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, 2,2'-bis(o-nitrophenyl)-4,4',5,5'-tetraphenylbiimidazole, 2,2'-bis(o-methylphenyl)-4,4',5,5'-tetraphenylbiimidazole, and the like.

[0037] Examples of benzophenone compounds include 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, and the like.

[0038] Examples of thioxanthone compounds include thioxanthone, 2-isopropylthioxanthone, 2-dodecylthioxanthone, 2-cyclohexylthioxanthone, 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 1-phenoxythioxanthone, 1-methoxycarbonylthioxanthone, 2-ethoxycarbonylthioxanthone, 3-(2-methoxyethoxycarbonyl)-thioxanthone, 4-butoxycarbonylthioxanthone, 3-butoxycarbonyl-7-methylthioxanthone, 3,4-di-[2-(2-methoxyethoxy)-ethoxycarbonyl]-thioxanthone, 2-chlorothioxanthone, 1-ethoxycarbonyl-3-ethoxythioxanthone, 1-ethoxycarbonyl-3-chlorothioxanthone, 1-chloro-4-n-propoxythioxanthone, 2-methyl-6-dimethoxymethyl-thioxanthone, 2-methyl-6-(1,1-dimethoxybenzyl)-thioxanthone, 6-ethoxycarbonyl-2-methoxy-thioxanthone, 6-ethoxycarbonyl-2-methylthioxanthone, 1-ethoxycarbonyl-3-(1-methyl-1-morpholinoethyl)-thioxanthone, 2-morpholinomethylthioxanthone, 2-methyl-6-morpholinomethylthioxanthone, thioxanthone-2-carboxylic acid polyethylene glycol ester, and the like.

[0039] 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, and the like.

[0040] Examples of α-diketone compounds include compounds such as benzyl (also known as diphenylethane dione or dibenzoyl).

[0041] (Component (B-1) may be a compound that absorbs light with a wavelength of 405 nm. Component (B-1) may be a compound having a larger extinction coefficient at a wavelength of 405 nm than component (B-2).)

[0042] (The extinction coefficient of component (B-1) at a wavelength of 405 nm may be 7 or more. When the extinction coefficient of component (B-1) at a wavelength of 405 nm is within the above range, the effects of the present invention will be more significantly exhibited.)

[0043] In this specification, the extinction coefficients of Omnirad TPO (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide), Omnirad 754, and Omnirad MBF are values measured in acetonitrile, and the extinction coefficients of other compounds are values measured in methanol (unit: mL / g·cm).

[0044] Examples of component (B-1) having an extinction coefficient at a wavelength of 405 nm of 7 or more include 2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole, 9-fluorenone, and the like.

[0045] (The content of component (B-1) may be 0.5 part by mass or more, 1.5 parts by mass or more, 3 parts by mass or more, or 4 parts by mass or more with respect to 100 parts by mass of the photocurable composition. 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 with respect to 100 parts by mass of the photocurable composition.)

[0046] (Component (B-2): Intramolecular cleavage type photo radical generator) (Component (B-2) is a compound that undergoes photo-cleavage of itself upon irradiation with light to generate two radicals. As component (B-2), a compound that has been used as an intramolecular cleavage type photo radical polymerization initiator can be used.)

[0047] Examples of the intramolecular cleavage type photo radical generator include, for example, benzyl ketal type photo radical generators, α-aminoalkylphenone type photo radical generators, α-hydroxyalkylphenone type photo radical generators, α-hydroxyacetophenone type photo radical generators, and acylphosphine oxide type photo radical generators. Component (B-2) may be used alone or in combination of two or more.

[0048] Examples of the benzyl ketal type photo radical generator include 2,2-dimethoxy-1,2-diphenylethane-1-one (Omnirad651) and the like.

[0049] Examples of the α-aminoalkylphenone type photo radical generator include 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (Omnirad369), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (Omnirad907), 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butanone-1 (Omnirad379EG) and the like.

[0050] Examples of the α-hydroxyalkylphenone type photo radical generator include 1-hydroxy-cyclohexyl-phenyl-ketone (Omnirad184) and the like.

[0051] Examples of the α-hydroxyacetophenone type photo radical generator include 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl-propan-1-one (Omnirad127), 2-hydroxy-2-methyl-1-phenyl-propan-1-one (Omnirad1173) and the like.

[0052] Examples of acylphosphine oxide-based photo radical generators include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (Omnirad TPO H), bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Omnirad 819), and the like.

[0053] (Component B-2) may be a compound that absorbs light with a wavelength of 365 nm and substantially does not absorb light with a wavelength of 405 nm, or has an extinction coefficient at a wavelength of 405 nm smaller than that of (Component B-1). The extinction coefficient of (Component B-2) at a wavelength of 365 nm may be 49 or more. In this specification, "substantially does not absorb light with a wavelength of 405 nm" means that the extinction coefficient at a wavelength of 405 nm is 5 or less. (Component B-2) may be a compound having an extinction coefficient at a wavelength of 365 nm of 49 or more and an extinction coefficient at a wavelength of 405 nm of 5 or less. When the extinction coefficient of (Component B-2) at a wavelength of 405 nm and the extinction coefficient at a wavelength of 365 nm are within the above ranges, the effects of the present invention will be exhibited more remarkably.

[0054] Examples of (Component B-2) having an extinction coefficient at a wavelength of 365 nm of 49 or more and an extinction coefficient at a wavelength of 405 nm of 5 or less include, for example, Omnirad 651, Omnirad 1173, Omnirad 184, and the like.

[0055] (The content of Component B-2) 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 with respect to 100 parts by mass of the photocurable composition. The content of (Component B-2) 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 with respect to 100 parts by mass of the photocurable composition.

[0056] 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.

[0057] The photocurable composition may contain at least one hydrogen abstraction type photoinitiator selected from the group consisting of fluorenone and benzyl, and may contain one molecular cleavage type photoinitiator selected from the group consisting of 2,2-dimethoxy-1,2-diphenylethane-1-one and 2-hydroxy-2-methyl-1-phenylpropanone.

[0058] The photocurable composition may further contain other components other than component (A-1), component (A-2), component (B-1) and component (B-2). Examples of the other components include additives such as plasticizers, tackifiers such as tackifiers, antioxidants, leuco dyes, sensitizers, adhesion improvers such as coupling agents, polymerization inhibitors, light stabilizers, defoamers, fillers, chain transfer agents, thixotropy imparting agents, flame retardants, release agents, surfactants, lubricants, antistatic agents and the like. These additives can be known ones. The total content of the other components may be 0 to 95% by mass, 0.01 to 50% by mass, or 0.1 to 10% by mass based on the total amount of the photocurable composition.

[0059] The photocurable composition may be used as a varnish of the photocurable composition diluted with a solvent. Examples of the solvent component include aromatic hydrocarbons such as toluene, xylene, mesitylene, cumene, p - cymene; aliphatic hydrocarbons such as hexane, heptane; cyclic alkanes such as methylcyclohexane; cyclic ethers such as tetrahydrofuran, 1,4 - dioxane; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 4 - hydroxy - 4 - methyl - 2 - pentanone; esters such as methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, γ - butyrolactone; carbonates such as ethylene carbonate, propylene carbonate; amides such as N,N - dimethylformamide, N,N - dimethylacetamide, N - methyl - 2 - pyrrolidone (NMP), etc. The component (E) may be used alone or in combination of two or more. The content of the solid content in the varnish, that is, the total content other than the solvent in the varnish, may be 10 to 95% by mass, or 15 to 70% by mass, or 20 to 50% by mass based on the total mass of the varnish.

[0060] The photocurable composition can be prepared, for example, by a method comprising a step of mixing or kneading the components (A - 1), (A - 2), (B - 1), (B - 2), and (A - 3), and components added as required. Mixing and kneading can be appropriately carried out in combination with ordinary stirrers, dispersers such as high - shear mixers, three - roll mills, ball mills, bead mills, etc.

[0061] The photocurable composition can form a cured product by light irradiation. By irradiating the photocurable composition with light, the thiol - ene reaction with the components (A - 1) and (A - 2) proceeds. The thiol - ene reaction proceeds starting from the hydrogen abstraction of the hydrogen of the thiol group in the component (A - 1) by a hydrogen - abstraction type photo - radical generator when irradiated with light. The reaction product of the components (A - 1) and (A - 2) contains, for example, a compound represented by the following formula. The cured product contains the reaction product of the components (A - 1) and (A - 2) and an intramolecular cleavage type photo - radical generator.

[0062] [Chemical formula]

[0063] In the formula, X represents a first linking group, and Y represents a second linking group. m represents an integer of 1 or more. m may be, for example, 25 or more, or 50 or more, or 100 or more, or 250 or more.

[0064] For example, by irradiating the photocurable composition with first light containing light having a wavelength of 405 nm, a cured product of the photocurable composition can be formed. The exposure amount of the first light may be, for example, 20000 mJ / cm 2 or more. In this specification, the exposure amount means 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 may be performed through glass or the like. The light source used for light irradiation is not particularly limited, and examples thereof include 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.

[0065] The cured product of the photocurable composition can be formed into various shapes. For example, a cured product formed in a film shape (film shape) can be used as a resin film. A cured product formed in a block shape can be used as a resin block. The method for forming a cured product in a film shape (film shape) or a block shape is not particularly limited, and a known method can be applied.

[0066] The storage modulus at 25°C of the cured product of the photocurable composition may be 5000 Pa or more, or 7000 Pa or more, or 100000 Pa or more. The storage modulus at 25°C of the cured product of the photocurable composition is not particularly limited, but may be, for example, 1000 MPa or less. In this specification, the storage modulus at 25°C means the value measured by the method described in the examples.

[0067] The cured product has the property of being photo-melted by light irradiation. For example, the cured product can be melted by irradiating it with a second light containing light with a wavelength of 365 nm. The exposure amount of the second light may be, for example, 5000 mJ / cm 2 or more. The light irradiation may be performed directly on the object to be irradiated, or may be performed through glass or the like. The light source and the like when irradiating the light may be the same as those described above.

[0068] When irradiated with light, the intramolecular cleavage type photo radical generator cleaves the disulfide bond (-S-S-) in the reaction product of the (A-1) component and the (A-2) component. As a result, the reaction product of the (A-1) component and the (A-2) component is reduced in molecular weight and becomes a liquid (liquid state). Since the cured product of the above-described photocurable composition is melted by light irradiation, it can also be called a photo-melting composition. The photo-melting composition contains the reaction product of the (A-1) component and the (A-2) component and an intramolecular cleavage type photo radical generator.

[0069] The storage modulus at 25 °C of the cured product of the photocurable composition after light irradiation may be 100 Pa or less, 10 Pa or less, or 8.5 Pa or less. The storage modulus at 25 °C of the cured product of the photocurable composition is not particularly limited, but may be, for example, more than 0 MPa.

[0070] The photocurable composition of the present embodiment can be used in applications such as adhesives, temporary fixing materials, photoresists, resins for 3D printers, and resins for molding materials.

[0071] The adhesive set of the present embodiment includes a first component containing a dithiol compound ((A-1) component) having a disulfide bond and a second component containing a compound ((A-2) component) having two ethylenically unsaturated groups. At least one of the first component and the second component further contains a hydrogen abstraction type photo radical generator ((B-1) component), and at least one of the first component and the second component further contains an intramolecular cleavage type photo radical generator ((B-2) component). At least one of the first component and the second component may further contain the above-described other components.

[0072] When mixing the first component and the second component, the equivalent ratio (molar ratio) of the (A-1) component to the (A-2) component may be, for example, 0.8 to 1.2.

[0073] 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.

[0074] Examples of the method for mixing the first component and the second component include a method of manually mixing using a spatula or the like, a method of mixing by manual coating using a normal caulking gun, a method of using a quantitative pump (for example, a gear pump, a plunger pump, etc.) for feeding the raw materials in combination with a throttle valve, and a method of mixing using a mechanical rotary mixer, a static mixer, or the like.

[0075] The prepared adhesive composition can form a cured product of the adhesive composition by light irradiation and can act as an adhesive layer for adhering adherends to each other. For example, the adhesive composition can be cured by irradiating light containing light with a wavelength of 405 nm.

[0076] The adhesive composition containing the first component and the second component has adhesiveness, and the cured product of the adhesive composition has photo-melting properties by light irradiation. Therefore, the adhesive composition can also be used as an adhesive having reparability.

[0077] An adherend of one embodiment includes a first adherend, a second adherend, and an adhesive layer that adheres the first adherend and the second adherend to each other. The adhesive layer contains a cured product of a photocurable composition.

[0078] Examples of the first adherend and the second adherend include plastics such as polyolefin resin, polyamide resin, ABS, PC, PET, PPS, and acrylic resin, wood, rubber, or inorganic materials such as steel, stainless steel, aluminum, copper, nickel, chromium or its alloy, glass, and silicon wafer.

[0079] The adhesive body includes a step of bonding the first adherend and the second adherend via a photocurable composition. The curing conditions and the like may be the same as those described above.

[0080] A method for separating adherends according to one embodiment includes a step of irradiating light onto the adhesive layer of the adhesive body to separate the first adherend and the second adherend. Since the adhesive layer contains a cured product of the photocurable composition described above, by irradiating light, the cured product of the photocurable composition can be melted to easily separate the adherends from each other.

[0081] In the method for separating adherends, the type of light, light source, etc. when irradiating light may be the same as those described above.

Examples

[0082] Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

[0083] The following compounds were prepared. (Component (A-1)): · Thiol LP-55 (a dithiol compound having a disulfide bond, manufactured by Toray Fine Chemical Co., Ltd.) (Component (A-2)): · Diallyl terephthalate (number of allyl groups: 2, manufactured by Tokyo Chemical Industry Co., Ltd.) · Triethylene glycol divinyl ether (number of vinyl ether groups: 2, manufactured by Tokyo Chemical Industry Co., Ltd.) (Component (B-1)): · Fluorenone (manufactured by Fujifilm Wako Pure Chemical Corporation) · Benzyl (manufactured by Fujifilm Wako Pure Chemical Corporation) (Component of (B-2)) · 2,2-Dimethoxy-1,2-diphenylethan-1-one (manufactured by IGM Resins B.V., trade name Omnirad 651) · 2-Hydroxy-2-methyl-1-phenylpropan-1-one (manufactured by IGM Resins B.V., trade name Omnirad 1173)

[0084] [Preparation of Photopolymerizable Compound] The components (A-1), (A-2), (B-1), and (B-2) with the compositions and amounts (unit: parts by mass) shown in Table 1 were added to a 125 ml ointment pot, and mixed at 2000 rpm for 3 minutes using a planetary stirrer (manufactured by Shinki Co., Ltd., trade name: Aretaro ARE-310 with foam removal). Next, the entire ointment pot was heated at 90 °C for 1 hour using a box dryer, and then mixed again at 2000 rpm for 3 minutes using the planetary stirrer to obtain a photocurable composition.

[0085] Using a viscoelasticity measuring device (manufactured by TA Instruments, trade name: DHR-2), the change in storage modulus at 25 °C with respect to the light irradiation time was measured by irradiating the evaluation sample with ultraviolet light from the optically transparent bottom surface. The light irradiation was performed using an LED lamp (manufactured by Panasonic Device SUNX Co., Ltd., trade names: Aicure UJ30 / ANUJ6186 and ANUJ6189), and exposed at the wavelength and exposure amount shown in Table 1 as the first wavelength. Thereafter, it 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 light irradiation, after light irradiation at the first wavelength, and after the second light irradiation.

[0086]

Table 1

[0087] As shown in Table 1, it was shown that a photocurable composition containing a dithiol compound having a disulfide bond, a compound having two ethylenically unsaturated groups, a hydrogen abstraction type photo radical generator, and an intramolecular cleavage type photo radical generator can form a cured product that can be melted by light irradiation.

Claims

1. A dithiol compound having a disulfide bond, a compound having two ethylenically unsaturated groups, a hydrogen abstraction type photo radical generator, and an intramolecular cleavage type photo radical generator, a photocurable composition containing the same.

2. The 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.

3. The absorption coefficient of the hydrogen abstraction type photo radical generator at a wavelength of 405 nm is 7 or more, the absorption coefficient of the intramolecular cleavage type photo radical generator at a wavelength of 405 nm is 5 or less, and the absorption coefficient at a wavelength of 365 nm is 49 or more, the photocurable composition according to claim 1 or 2.

4. The photocurable composition according to any one of claims 1 to 3, wherein the hydrogen abstraction type photo radical generator contains at least one selected from the group consisting of fluorenone and benzyl.

5. The photocurable composition according to any one of claims 1 to 4, wherein the intramolecular cleavage type photo radical generator contains one selected from the group consisting of 2,2-dimethoxy-1,2-diphenylethane-1-one and 2-hydroxy-2-methyl-1-phenylpropanone.

6. The photocurable composition according to any one of claims 1 to 5, which is used as an adhesive.

7. A cured product of the photocurable composition according to any one of claims 1 to 6.

8. A reaction product of a dithiol compound having a disulfide bond and a compound having two ethylenically unsaturated groups, and a photo-melting resin composition containing an intramolecular cleavage type photo radical generator.

9. A first component containing a dithiol compound having a disulfide bond, and a second component containing a compound having two ethylenically unsaturated groups, including at least one of the first component and the second component further contains a hydrogen abstraction type photo radical generator, at least one of the first component and the second component further contains an intramolecular cleavage type photo radical generator, an adhesive set.

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