Photocurable adhesive composition, bonded body, and 2-cyanoacrylate composition for photocurable adhesive

Abstract

A photocurable adhesive composition containing: a 2-cyanoacrylate compound that has a phosphorus content derived from acidic phosphate ester compounds of 30 mass ppm or less; a group 8 transition metal metallocene compound; and a photoradical generator. A photocurable adhesive composition containing: a 2-cyanoacrylate compound that has an acidic phosphate ester compound content of 150 mass ppm or less; a group 8 transition metal metallocene compound; and a photoradical generator. A photocurable adhesive composition containing a 2-cyanoacrylate compound, a group 8 transition metal metallocene compound, and a photoradical generator, in which the phosphorus content derived from the acidic phosphate ester compounds is 30 mass ppm or less.

Description

Photocurable adhesive composition, bonded structure, and 2-cyanoacrylate composition for photocurable adhesive

[0001] [Cross-reference to related applications] This application claims priority to Japanese Patent Application No. 2023-150189 filed on September 15, 2023, and Japanese Patent Application No. 2023-212793 filed on December 18, 2023, both of which are incorporated herein by reference in their entireties. The present disclosure relates to a photocurable adhesive composition, a bonded structure, and a 2-cyanoacrylate composition for use in a photocurable adhesive, and more particularly to a cyanoacrylate-based photocurable adhesive composition, a bonded structure in which adherends are bonded together by means of the composition, and a 2-cyanoacrylate composition used in producing the cyanoacrylate-based photocurable adhesive composition.

[0002] Cyanoacrylate instant adhesives are one-component, solvent-free adhesives that cure in the presence of moisture in the air or on the surface of a substrate (moisture-curing properties) and cure instantly even at room temperature. Because of these characteristics, cyanoacrylate instant adhesives are widely used as industrial and general-purpose adhesives (see, for example, Patent Document 1).

[0003] In recent years, adhesive compositions have been proposed that combine the property of being cured by light irradiation (photocurability) with the conventional moisture curability (see, for example, Patent Document 2). Patent Document 2 discloses a photocurable adhesive composition containing a photoinitiator system selected from a ferrocene compound and an acylgermane compound, a cyanoacrylate compound, and an acid stabilizer compound selected from Lewis acids.

[0004] JP 2022-101160 A International Publication No. 2017 / 021785

[0005] The inventors of the present invention have conducted studies and found that photocurable adhesive compositions containing a Group 8 transition metal metallocene compound and a photoradical generator together with a 2-cyanoacrylate compound may experience deterioration in photocurability over time.

[0006] The present disclosure has been made in view of the above circumstances, and a primary object of the present disclosure is to provide a photocurable adhesive composition that can suppress deterioration of photocurability over time. Another object of the present disclosure is to provide a 2-cyanoacrylate composition for photocurable adhesives that can suppress deterioration of photocurability over time.

[0007] As a result of extensive research to solve the above problems, the present inventors have discovered that a specific compound is contained in the raw material 2-cyanoacrylate compound, and that the inclusion of this specific compound in a greater than predetermined amount causes deterioration of the photocurability of the photocurable adhesive composition over time. This discovery has led to the completion of the present disclosure. Specifically, the present disclosure provides the following photocurable adhesive composition, bonded structure, and 2-cyanoacrylate composition for photocurable adhesive.

[0008] [1] A photocurable adhesive composition comprising a 2-cyanoacrylate compound having a phosphorus content derived from an acidic phosphate ester compound of 30 ppm by mass or less, a Group 8 transition metal metallocene compound, and a photoradical generator. [2] The photocurable adhesive composition of [1] above, in which the content of the acidic phosphate ester compound in the 2-cyanoacrylate compound is 150 ppm by mass or less. [3] The photocurable adhesive composition of [1] or [2] above, in which the content of phosphorus derived from the acidic phosphate ester compound in the composition is 30 ppm by mass or less. [4] A photocurable adhesive composition comprising a 2-cyanoacrylate compound having a phosphorus content of 150 ppm by mass or less, a Group 8 transition metal metallocene compound, and a photoradical generator. [5] A photocurable adhesive composition containing a 2-cyanoacrylate compound, a Group 8 transition metal metallocene compound, and a photoradical generator, wherein the phosphorus content derived from the acidic phosphate ester compound is 30 ppm by mass or less. [6] The photocurable adhesive composition of any of [1] to [5] above, wherein the photoradical generator is at least one selected from the group consisting of an acylgermane compound and an acylphosphine oxide compound. [7] The photocurable adhesive composition of any of [1] to [6] above, wherein the acidic phosphate ester compound is at least one selected from the group consisting of a phosphoric acid monoester compound and a phosphoric acid diester compound. [8] A bonded body in which adherends are bonded together with the photocurable adhesive composition of any of [1] to [7] above. [9] A 2-cyanoacrylate composition for photocurable adhesives used in the production of a photocurable adhesive composition containing a 2-cyanoacrylate compound, the 2-cyanoacrylate composition for photocurable adhesives containing an acidic phosphate ester compound, and having a phosphorus content derived from the acidic phosphate ester compound of more than 0 ppm by mass and not more than 30 ppm by mass.

[10] The 2-cyanoacrylate composition for photocurable adhesives of [9], wherein the photocurable adhesive composition contains a Group 8 transition metal metallocene compound and a photoradical generator.

[0009] The photocurable adhesive composition of the present disclosure can suppress deterioration of photocurability over time. This makes it possible to obtain a photocurable adhesive composition that exhibits excellent photocurability regardless of time. Furthermore, the 2-cyanoacrylate composition of the present disclosure can obtain a photocurable adhesive in which deterioration of photocurability over time is suppressed.

[0010] Matters related to the present disclosure will be described in detail below. In this specification, a numerical range indicated by "to" includes the numerical values ​​before and after it as the upper and lower limits.

[0011] <Photocurable Adhesive Composition> The photocurable adhesive composition of the present disclosure (hereinafter also referred to as the "first composition") contains a 2-cyanoacrylate compound, a Group 8 transition metal metallocene compound, and a photoradical generator. By containing these components, the first composition allows the 2-cyanoacrylate compound to react with moisture in the air or on the surface of a substrate to instantaneously cure, and upon irradiation with active energy rays, curing proceeds in the unreacted portions with moisture. In other words, the first composition has both moisture-curing and photocuring properties. This allows the first composition to exhibit high adhesive performance and be applicable to a variety of applications.

[0012] In particular, the present disclosure focuses on the fact that in a photocurable adhesive composition containing a 2-cyanoacrylate compound, a Group 8 transition metal metallocene compound, and a photoradical generator, the photocurability of the photocurable adhesive composition may deteriorate over time due to impurities contained in the 2-cyanoacrylate compound, which is a raw material. The inventors speculated that the deterioration in photocurability over time is due to the acidic phosphate ester compound contained in the 2-cyanoacrylate compound, and found that by controlling the amount of the 2-cyanoacrylate compound and / or the acidic phosphate ester compound in the photocurable adhesive composition, the photocurability of the photocurable adhesive composition was improved, and it was possible to obtain a photocurable adhesive composition that can exhibit excellent photocurability over a long period of time.

[0013] Specifically, the first composition contains a 2-cyanoacrylate compound, a Group 8 transition metal metallocene compound, and a photoradical generator, and satisfies one or more of the following requirements 1, 2, and 3. Requirement 1: The 2-cyanoacrylate compound, which is a raw material for the photocurable adhesive composition, contains 30 ppm by mass or less of phosphorus derived from acidic phosphate ester compounds. Requirement 2: The 2-cyanoacrylate compound, which is a raw material for the photocurable adhesive composition, contains 150 ppm by mass or less of acidic phosphate ester compounds. Requirement 3: The photocurable adhesive composition contains 30 ppm by mass or less of phosphorus derived from acidic phosphate ester compounds.

[0014] The reason why acidic phosphate ester compounds are contaminated as impurities in 2-cyanoacrylate compound products is thought to be due to the manufacturing process of the 2-cyanoacrylate compound. Specifically, 2-cyanoacrylate compounds are generally produced by subjecting cyanoacetate and formaldehyde to a dehydration condensation reaction in the presence of a base catalyst, followed by heating and depolymerizing the resulting condensate. Furthermore, in the manufacturing process of 2-cyanoacrylate compounds, phosphoric acid compounds (e.g., phosphoric acid or diphosphorus pentoxide) are sometimes used as depolymerization catalysts and / or anionic polymerization inhibitors. In this case, the phosphoric acid compound reacts with decomposition products generated during polymerization (specifically, alcohols having a structure corresponding to the ester moiety of 2-cyanoacrylate), and the acidic phosphate ester compounds thus produced are thought to be present as impurities in the 2-cyanoacrylate compound products. Below, each component contained in the first composition is specifically described.

[0015] (2-Cyanoacrylate Compound) The 2-cyanoacrylate compound contained in the first composition includes a compound represented by the following formula (1): CH ２ =C(CN)-COOR １ ...(1) (In formula (1), R １represents a saturated or unsaturated linear hydrocarbon group having 1 to 20 carbon atoms which may have a halogen atom or an ether bond, a saturated or unsaturated branched hydrocarbon group having 3 to 20 carbon atoms which may have a halogen atom or an ether bond, a saturated or unsaturated alicyclic hydrocarbon group having 3 to 20 carbon atoms which may have a halogen atom or an ether bond, or an aromatic hydrocarbon group having 5 to 20 carbon atoms which may have a halogen atom or an ether bond.

[0016] Specific examples of 2-cyanoacrylate compounds include those in which the hydrogen atom in the carboxyl group of 2-cyanoacrylic acid is replaced with a methyl group, an ethyl group, a chloroethyl group, an n-propyl group, an i-propyl group, an allyl group, a propargyl group, an n-butyl group, an i-butyl group, an n-pentyl group, an n-hexyl group, an amyl group, a 2-methyl-3-butenyl group, a 3-methyl-3-butenyl group, a 2-pentenyl group, a 6-chlorohexyl group, a cyclohexyl group, a phenyl group, a tetrahydrofurfuryl group, a 2-hexenyl group, a 4-methylpentenyl group, a 3-methyl-2-cyclohexenyl group, a norbornyl group, a heptyl group, a cyclohexanemethyl group, a cycloheptyl group, a 1-methylcyclohexyl group, a 2-methylcyclohexyl group, a 3-methyl-cyclohexyl group, a 2-ethylhexyl group, an n-octyl group, a 2-octyl group, a cyclooctyl group, a cyclopenten ... and ester compounds in which each of the alkyl groups is substituted with a methyl group, a 2,3-dimethylcyclohexyl group, an n-nonyl group, an isononyl group, an oxononyl group, an n-decyl group, an isodecyl group, an n-dodecyl group, a 2-methoxyethyl group, a 2-ethoxyethyl group, a 2-ethoxy-2-ethoxyethyl group, a butoxyethoxyethyl group, a 1-(2-methoxy-1-methylethoxy)propyl group, a 2,2,2-trifluoroethyl group, a hexafluoroisopropyl group, a lauryl group, an isotridecyl group, a myristyl group, a cetyl group, a stearyl group, an oleyl group, a behenyl group, a hexyldecyl group, an octyldodecyl group, a benzyl group, a chlorophenyl group, a 2-pentyloxyethyl group, a 2-hexyloxyethyl group, a 2-cyclohexyloxyethyl group, a 2-(2-ethylhexyloxy)ethyl group, or a 2-phenoxyethyl group.

[0017] Among the above-mentioned 2-cyanoacrylate compounds, preferred are ester compounds in which the hydrogen atom in the carboxyl group of 2-cyanoacrylic acid is replaced with a saturated linear hydrocarbon group having 1 to 10 carbon atoms which may have an ether bond, a saturated branched chain hydrocarbon group having 3 to 10 carbon atoms which may have an ether bond, a saturated aliphatic cyclic hydrocarbon group having 3 to 12 carbon atoms which may have an ether bond, or an aromatic hydrocarbon group having 6 to 12 carbon atoms. Of these, the 2-cyanoacrylate compound is particularly preferably an ester compound in which the hydrogen atom in the carboxyl group of 2-cyanoacrylic acid is replaced with a methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, cyclohexyl group, phenyl group, tetrahydrofurfuryl group, 2-ethylhexyl group, n-octyl group, 2-octyl group, 2-methoxyethyl group, 2-ethoxyethyl group, or 1-(2-methoxy-1-methylethoxy)propyl group. The first composition may contain one type of 2-cyanoacrylate compound alone or two or more types.

[0018] In preparing the first composition, the 2-cyanoacrylate compound used as a raw material preferably satisfies the above-mentioned requirement 1. By using a 2-cyanoacrylate compound having a phosphorus content derived from an acidic phosphate ester compound of 30 ppm by mass or less, a photocurable adhesive composition can be obtained in which deterioration of photocurability over time is sufficiently suppressed. Note that when the 2-cyanoacrylate compound used as a raw material satisfies the above-mentioned requirement 1, the 2-cyanoacrylate compound may also satisfy requirement 2.

[0019] In the present disclosure, an acidic phosphate ester compound refers to a partial ester of an alcohol and phosphoric acid. The acidic phosphate ester compound contained in the 2-cyanoacrylate compound and / or the first composition is typically an impurity generated in the manufacturing process of the 2-cyanoacrylate compound. The acidic phosphate ester compound may be at least one selected from the group consisting of a phosphoric acid monoester compound and a phosphoric acid diester compound. Specific examples of the acidic phosphate ester compound include compounds represented by the following formula (2): (R ２ O) ｎ P(=O)(OH) ３－ｎ ...(2) (In formula (2), R ２ are the same or different and represent a saturated or unsaturated linear hydrocarbon group having 1 to 20 carbon atoms which may have a halogen atom or an ether bond, a saturated or unsaturated branched hydrocarbon group having 3 to 20 carbon atoms which may have a halogen atom or an ether bond, a saturated or unsaturated alicyclic hydrocarbon group having 3 to 20 carbon atoms which may have a halogen atom or an ether bond, or an aromatic hydrocarbon group having 5 to 20 carbon atoms which may have a halogen atom or an ether bond; and n represents 1 or 2.

[0020] Specific examples of the 2-cyanoacrylate compound and / or the acidic phosphate ester compound contained in the first composition include compounds represented by R ２ is a group corresponding to a 2-cyanoacrylate compound. The 2-cyanoacrylate compound and / or the acidic phosphate ester compound contained in the first composition may be a compound having an ester group in a 2-cyanoacrylate compound (R １Depending on the type of R, examples include monomethyl phosphate, dimethyl phosphate, monoethyl phosphate, diethyl phosphate, monopropyl phosphate, dipropyl phosphate, monobutyl phosphate, dibutyl phosphate, monooctyl phosphate, dioctyl phosphate, mono-2-ethylhexyl phosphate, monocyclohexyl phosphate, dicyclohexyl phosphate, mono-2-methoxyethyl phosphate, di-2-methoxyethyl phosphate, mono-2-ethoxyethyl phosphate, di-2-ethoxyethyl phosphate, monophenyl phosphate, diphenyl phosphate, monotetrahydrofurfuryl phosphate, ditetrahydrofurfuryl phosphate, etc. ２ However, a compound having a group different from the group corresponding to the 2-cyanoacrylate compound may be contained as an acidic phosphoric acid ester compound in the 2-cyanoacrylate compound and / or the first composition.

[0021] The phosphorus content derived from the acidic phosphate ester compound in the 2-cyanoacrylate compound is more preferably 20 ppm by mass or less, even more preferably 15 ppm by mass or less, even more preferably 10 ppm by mass or less, and even more preferably 5 ppm by mass or less, in order to sufficiently enhance the effect of suppressing deterioration over time of photocurability. Note that, in this specification, the phosphorus content derived from the acidic phosphate ester compound in the 2-cyanoacrylate compound is a value measured by high-frequency inductively coupled plasma (ICP) atomic emission spectrometry.

[0022] The content of the acidic phosphate ester compound in the 2-cyanoacrylate compound is preferably 150 ppm by mass or less. By ensuring that the content of the acidic phosphate ester compound in the 2-cyanoacrylate compound is 150 ppm by mass or less (i.e., satisfying the above-mentioned requirement 2), deterioration of the photocurability of the photocurable adhesive composition over time can be sufficiently suppressed. From this perspective, the content of the acidic phosphate ester compound in the 2-cyanoacrylate compound is more preferably 120 ppm by mass or less, even more preferably 100 ppm by mass or less, even more preferably 80 ppm by mass or less, and even more preferably 50 ppm by mass or less. In this specification, the content of the acidic phosphate ester compound in the 2-cyanoacrylate compound is a value measured by gas chromatography.

[0023] In the first composition, the content of the 2-cyanoacrylate compound is preferably 40 mass % or more, and more preferably 60 mass % or more, relative to the total amount of the photocurable adhesive composition, from the viewpoints of curability, curing speed, and strength of the cured product.

[0024] The phosphorus content derived from the acidic phosphate ester compound and the content of the acidic phosphate ester compound in the 2-cyanoacrylate compound can be adjusted, for example, by appropriately selecting the purification method and number of purification steps for the 2-cyanoacrylate compound. The method for purifying the 2-cyanoacrylate compound is not particularly limited. For example, when the 2-cyanoacrylate compound is purified by distillation, examples of the distillation method include a method in which a 2-cyanoacrylate compound containing more than a predetermined amount of impurities is heated using a packed distillation column, a plate distillation column, or a rectification column.

[0025] (Group 8 Transition Metal Metallocene Compound) The Group 8 transition metal metallocene compound is not particularly limited as long as it is a metallocene compound containing a Group 8 transition metal element of the periodic table. It is believed that when an active energy ray is irradiated onto a photocurable adhesive composition containing a Group 8 transition metal metallocene compound and a photoradical generator together with a 2-cyanoacrylate compound, radicals generated by the photoradical generator attack the Group 8 transition metal metallocene compound to generate anions, thereby accelerating the anionic polymerization of the 2-cyanoacrylate compound. Based on this mechanism, the Group 8 transition metal metallocene compound is also referred to as a "synergist."

[0026] Although the reason why the presence of an acidic phosphate ester compound affects the deterioration of the photocurability of the photocurable adhesive composition is unclear, one hypothesis is that the acidic phosphate ester compound contained as an impurity in the 2-cyanoacrylate compound coexists with the Group 8 transition metal metallocene compound after the preparation of the photocurable adhesive composition, causing the Group 8 transition metal metallocene compound to degrade. That is, the acidic phosphate ester compound degrades the Group 8 transition metal metallocene compound in the photocurable adhesive composition, which gradually reduces the amount of anions generated from the Group 8 transition metal metallocene compound, resulting in deterioration of the photocurability of the photocurable adhesive composition over time. Based on this speculation, the first composition used a 2-cyanoacrylate compound as a raw material in which the phosphorus content derived from the acidic phosphate ester compound and / or the content of the acidic phosphate ester compound was below a predetermined amount. This successfully suppressed deterioration of the photocurability over time in the photocurable adhesive composition.

[0027] Examples of Group 8 transition metal metallocene compounds include ferrocene compounds in which the transition metal is iron, osmocene compounds in which the transition metal is osmium, ruthenocene compounds in which the transition metal is ruthenium, and cobaltocene compounds in which the transition metal is cobalt.

[0028] Specific examples of the Group 8 transition metal metallocene compound include ferrocene, ethylferrocene, n-butylferrocene, benzoylferrocene, acetylferrocene, t-amylferrocene, 1,1'-dimethylferrocene, 1,1'-di-n-butylferrocene, 1,1'-dibenzoylferrocene, 1,1'-di(acetylcyclopentadienyl)iron, bis(pentamethylcyclopentadienyl)iron, bis(cyclopentadienyl)osmium, bis(pentamethylcyclopentadienyl)osmium, ruthenocene (bis(cyclopentadienyl)ruthenium), bis(pentamethylcyclopentadienyl)ruthenium, etc. Furthermore, as the Group 8 transition metal metallocene compound, a transition metal metallocene compound of Group 8 of the periodic table having an aromatic electron system ligand, as described in JP-A-2003-277422, can also be preferably used.

[0029] From the viewpoints of curability and storage stability, the Group 8 transition metal metallocene compound incorporated into the photocurable adhesive composition is preferably at least one selected from the group consisting of ferrocene compounds and ruthenocene compounds, and more preferably a ferrocene compound.

[0030] From the viewpoints of curability, curing speed, cost-effectiveness, and storage stability, the Group 8 transition metal metallocene compound is preferably at least one selected from the group consisting of ferrocene, ethylferrocene, n-butylferrocene, benzoylferrocene, and ruthenocene, and more preferably at least one selected from the group consisting of ferrocene, benzoylferrocene, and ruthenocene. The photocurable adhesive composition may contain one or more Group 8 transition metal metallocene compounds.

[0031] From the viewpoints of curability and storage stability, the content of the Group 8 transition metal metallocene compound in the first composition is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, and even more preferably 0.0015% by mass or more, relative to the total amount of the photocurable adhesive composition. Furthermore, the upper limit of the content of the Group 8 transition metal metallocene compound is preferably 5% by mass or less, more preferably 1% by mass or less, and even more preferably 0.2% by mass or less. The content of the Group 8 transition metal metallocene compound is preferably in the range of 0.0001 to 5% by mass, and more preferably 0.001 to 1% by mass.

[0032] (Photoradical Generator) Examples of photoradical generators contained in the photocurable adhesive composition include acylgermane compounds, acylphosphine oxide compounds, alkylphenone compounds, acetophenone compounds, benzoin compounds, etc. From the viewpoints of the curability, curing speed, and storage stability of the photocurable adhesive composition, the photoradical generator is preferably at least one selected from the group consisting of acylgermane compounds and acylphosphine oxide compounds, and from the viewpoint of storage stability, an acylgermane compound is more preferred.

[0033] The acylgermane compound is preferably at least one selected from the group consisting of monoacylgermane compounds and bisacylgermane compounds, of which bisacylgermane compounds are more preferred.

[0034] Specific examples of the acylgermane compound include dibenzoyldiethylgermanium, bis(4-methoxybenzoyl)dimethylgermanium, bis(4-methoxybenzoyl)diethylgermanium, ferrocenylacylgermanium, benzoyldimethylgermanium, bis(4-methylbenzoyl)diethylgermanium, bis(4-methylbenzoyl)dimethylgermanium, and dibenzoyldibutylgermanium.

[0035] As the acylphosphine oxide compound, at least one selected from the group consisting of monoacylphosphine oxide compounds and bisacylphosphine oxide compounds can be preferably used, and among these, monoacylphosphine oxide compounds are more preferred.

[0036] Preferred examples of the monoacylphosphine oxide compound include compounds represented by the following formula (A-1).

[0037] (In formula (A-1), R Ａ１ and R Ａ２ each independently represents an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a phenyl group, or a phenyl group in which 1 to 3 hydrogen atoms are substituted by an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms; R Ａ３ represents a linear alkyl group having 1 to 18 carbon atoms, a branched alkyl group, or a cycloalkyl group having 3 to 12 carbon atoms; a linear alkyl group having 1 to 18 carbon atoms, a branched alkyl group, or a cycloalkyl group having 3 to 12 carbon atoms substituted with an acetyloxy group; an aryl group; an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or an aryl group substituted with a halogen atom; or a group represented by the following formula (A-2):

[0038] (In formula (A-2), R Ａ４ and R Ａ５ each independently represents an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a phenyl group, or a phenyl group substituted with 1 to 3 alkyl groups having 1 to 8 carbon atoms or alkoxy groups having 1 to 8 carbon atoms; X Ａ１ represents a p-phenylene group.

[0039] Specific examples of the monoacylphosphine oxide compound include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, methyl isobutyroylmethylphosphinate, methyl isobutyroylphenylphosphinate, methyl pivaloylphosphinate, methyl-2-ethylhexanoylphosphinate, isopropyl-2-ethylhexanoylphenylphosphonate, methyl-p-tolylphenylphosphinate, methyl-o-tolyl-phenylphosphinate, methyl-2,4-dimethylbenzoylphosphinate, Examples of the diphenylphosphine oxide include benzoylphenylphosphine oxide, methyl acryloylphenylphosphine oxide, methyl acyloylphenylphosphonate, isobutyroyldiphenylphosphine oxide, 2-methylhexanoyldiphenylphosphine oxide, o-toluyldiphenylphosphine oxide, p-t-butylbenzoyldiphenylphosphine oxide, 3-polyzylcarbonyldiphenylphosphine oxide, acryloyldiphenylphosphine oxide, benzoyldiphenylphosphine oxide, and adiboylbis(diphenylphosphine oxide).

[0040] A preferred example of the bisacylphosphine oxide compound is a compound represented by the following formula (A-3).

[0041] (R in formula (A-3) ｐ are each independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkylthio group having 1 to 8 carbon atoms, or a halogen atom, and each R ｐ may be the same or different.)

[0042] R in formula (A-3) ｐ The alkyl group having 1 to 12 carbon atoms in formula (A-3) may be linear or branched, and examples thereof include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, hexyl, heptyl, octyl, nonyl, decyl, and dodecyl. The alkyl group having 1 to 12 carbon atoms preferably has 1 to 6 carbon atoms, and more preferably has 1 to 4 carbon atoms. R in formula (A-3) ｐThe alkylthio group having 1 to 8 carbon atoms in the formula (I) may be linear or branched, and examples thereof include a methylthio group, an ethylthio group, a propylthio group, an isopropylthio group, a butylthio group, a tert-butylthio group, a hexylthio group, and an octylthio group. Of these, a methylthio group is preferred. Examples of halogen atoms include a chlorine atom, a bromine atom, and an iodine atom. Of these, a chlorine atom is preferred.

[0043] Specific examples of the bisacylphosphine oxide compound include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and the like.

[0044] Examples of the acetophenone compound include 4-phenoxydichloroacetophenone, 4-t-butyldichloroacetophenone, 4-t-butyltrichloroacetophenone, and diethoxyacetophenone.

[0045] Examples of the benzoin compound include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyl methyl ketal, etc. The photocurable adhesive composition may contain one type of photoradical generator alone or two or more types.

[0046] From the viewpoints of the curability, curing rate, and storage stability of the photocurable adhesive composition, the content of the photoradical generator in the first composition is preferably 0.01 to 5 mass %, more preferably 0.02 to 2 mass %, and even more preferably 0.05 to 1 mass %, relative to the total amount of the photocurable adhesive composition.

[0047] In the first composition, the mass ratio of the photoradical initiator to the Group 8 transition metal metallocene compound (photoradical initiator / Group 8 transition metal metallocene compound) is preferably 10 to 1,000, more preferably 15 to 500, and even more preferably 15 to 90.

[0048] (Other Components) The first composition may further contain a component (hereinafter also referred to as "other component") other than the 2-cyanoacrylate compound, the Group 8 transition metal metallocene compound, and the photoradical generator. Examples of the other component include a thickener, an organic thixotropic agent, and silica.

[0049] Thickener The first composition may contain a thickener for the purpose of adjusting the viscosity of the photocurable adhesive composition. As the thickener, a compound known as an additive for imparting viscosity can be appropriately used.

[0050] Specific examples of thickeners include polymethyl methacrylate, copolymers of methyl methacrylate and acrylic esters, copolymers of methyl methacrylate and methacrylic esters other than methyl methacrylate, acrylic rubber, polyvinyl chloride, polystyrene, cellulose esters, polyalkyl-2-cyanoacrylates, ethylene-vinyl acetate copolymers, vinyl chloride-vinyl acetate copolymers, (meth)acrylic ester-butadiene-styrene copolymers, vinyl chloride-acrylonitrile copolymers, ethylene-vinyl acetate copolymers, lactic acid-caprolactone copolymers, cellulose acetate, cellulose acetate propionate, polyvinyl acetate, polyvinylpyrrolidone, etc. The photocurable adhesive composition may contain one type of thickener alone, or two or more types.

[0051] When a thickener is blended into the first composition, from the viewpoint of appropriately increasing the viscosity of the photocurable adhesive composition, the content of the thickener is preferably 2 mass % or more, more preferably 5 mass % or more, and even more preferably 8 mass % or more, based on the total amount of the photocurable adhesive composition. Furthermore, from the viewpoint of suppressing a decrease in the curability of the photocurable adhesive composition due to an excessive amount of thickener, the content of the thickener is preferably 30 mass % or less, more preferably 25 mass % or less, based on the total amount of the photocurable adhesive composition.

[0052] Organic thixotropic agents are optionally blended in order to adjust the flow behavior of the photocurable adhesive composition. Examples of organic thixotropic agents include hydrogenated castor oil, amine-modified hydrogenated castor oil, and polyamides. In the case of amine-modified hydrogenated castor oil, the amine compound used to modify the hydrogenated castor oil is preferably an aliphatic diamine. Specific examples of aliphatic diamines include 1,2-ethylenediamine, 1,3-propanediamine, and 1,6-hexanediamine.

[0053] When an organic thixotropic agent is blended into the first composition, the content of the organic thixotropic agent is, for example, 2 to 10 mass % relative to the total amount of the photocurable adhesive composition.

[0054] Silica Silica is an inorganic thixotropic agent that is optionally added to the photocurable adhesive composition to adjust its flow behavior. Examples of silica include hydrophobic fumed silica, precipitated silica, or a combination thereof. When silica is added to the first composition, the content of silica is, for example, 1 to 10 mass % based on the total amount of the photocurable adhesive composition.

[0055] In addition to the above, other components include, for example, a stabilizer (polymerization inhibitor), a plasticizer, an anionic polymerization accelerator, an inorganic filler, a colorant, a fragrance, a solvent, a strength improver, etc. The contents of these components can be appropriately set depending on the application of the first composition, etc., within a range that does not impair the effects of the present disclosure.

[0056] (Phosphorus Content Derived from Acidic Phosphate Ester) The phosphorus content derived from the acidic phosphate ester compound in the first composition is preferably 30 ppm by mass or less (i.e., satisfying the above-mentioned requirement 3). When the phosphorus content derived from the acidic phosphate ester compound in the photocurable adhesive composition is 30 ppm by mass or less, deterioration of the photocurability of the photocurable adhesive composition over time can be sufficiently suppressed, and a decrease in productivity due to poor photocurability can be suppressed. From the viewpoint of obtaining a photocurable adhesive composition that exhibits stable photocurability, the phosphorus content derived from the acidic phosphate ester compound in the first composition is more preferably 20 ppm by mass or less, even more preferably 15 ppm by mass or less, even more preferably 10 ppm by mass or less, and even more preferably 5 ppm by mass or less. Note that, in this specification, the phosphorus content derived from the acidic phosphate ester compound in the first composition is a value measured by ICP atomic emission spectroscopy.

[0057] The first composition is preferably a liquid composition comprising a mixture of a 2-cyanoacrylate compound, a Group 8 transition metal metallocene compound, a photoradical generator, and other optional components. The viscosity of the first composition is preferably 5 mPa·s or more, more preferably 10 mPa·s or more, and even more preferably 20 mPa·s or more. The viscosity of the first composition is preferably 5,000 mPa·s or less, more preferably 4,000 mPa·s or less, and even more preferably 3,000 mPa·s or less. By ensuring that the viscosity of the first composition falls within the above range, the coating properties and handleability of the composition on an adherend can be improved. In this specification, the viscosity of the photocurable adhesive composition is a value measured at 25°C using an E-type viscometer (cone-plate type viscometer).

[0058] (Uses) The first composition can be used as a so-called instant adhesive because it can instantly bond adherends together. Examples of the adherend include substrates formed from resin, metal, ceramic, rubber, glass, wood, cloth, porcelain, leather, or a combination of two or more of these. The adherend may further contain a reinforcing material such as carbon fiber or glass fiber, a colorant, or the like.

[0059] Among the above, examples of resins include vinyl chloride resins (polyvinyl chloride, ethylene-vinyl chloride copolymer, polyvinylidene chloride, etc.), polyvinyl acetate resin, polyurethane resin, polystyrene resin, AS resin (acrylonitrile-styrene copolymer), ABS resin (acrylonitrile-butadiene-styrene copolymer), AXS resin (styrene copolymer of a rubber component other than acrylonitrile-butadiene), acrylic resin, polymethyl methacrylate resin, polyester resin, polyamide resin, polybutylene terephthalate resin, polycarbonate resin, polyphenylene sulfide (PPS) resin, and polyether ether ketone (PEEK) resin.

[0060] Examples of metals include copper, aluminum, iron, gold, silver, titanium, nickel, zinc, tin, alloy steel (stainless steel, manganese steel, nickel steel, etc.), and composites of two or more of these.

[0061] The method for applying the first composition to the adherend is not particularly limited. For example, various methods can be used, such as dropping the first composition onto the adherend or applying the first composition to the adherend in a line, band, or dot pattern. The first composition may be applied to the entire surface of the adherend, or may be applied locally. The amount of the first composition to be applied is not particularly limited, but it is preferable to use an appropriately small amount to instantly develop high adhesive strength. The first composition containing a 2-cyanoacrylate compound, a Group 8 transition metal metallocene compound, and a photoradical generator can develop sufficiently high adhesive strength with a small amount. The specific application amount is typically 1 to 10 mg / cm. ２ and preferably 2 to 8 mg / cm ２ is.

[0062] After bonding the adherends together via the first composition, the first composition is irradiated with active energy rays, thereby causing a curing reaction of the 2-cyanoacrylate compound (i.e., unreacted monomer) in the composition that has not come into contact with moisture. Examples of active energy rays include ultraviolet light, visible light, and electron beams. Of these, ultraviolet light or visible light is preferred, and ultraviolet light or visible light with a wavelength of 300 to 550 nm is more preferred. The irradiation energy can be appropriately set depending on the type of active energy rays, the formulation of the photocurable adhesive composition, and the like.

[0063] The light source of the active energy rays is not particularly limited, and examples thereof include ultraviolet light-emitting diodes (UV-LEDs), high-pressure mercury lamps, halogen lamps, xenon lamps, and deuterium lamps. ２ More than 20 mJ / cm is preferable. ２ or more, and 50 mJ / cm ２ Furthermore, the upper limit of the cumulative light amount is set to 500 mJ / cm from the viewpoint of reducing energy. ２ Preferably, 300 mJ / cm or less ２ The following is more preferable: The illuminance and irradiation time of the ultraviolet light may be appropriately set so that the integrated light amount becomes a desired amount.

[0064] The above method can produce a bonded structure in which adherends are bonded together with the first composition. The first composition has photocurability and moisture curability, and exhibits excellent curing properties, making it suitable for use as an instant adhesive in a wide range of fields, including general, industrial, and medical applications. Specifically, the composition can be used for bonding, fixing, or coating between similar or different types of items, such as sealing electronic components; attaching reel seats or threading guides to fishing rods; fixing wires such as coils; fixing magnetic heads to bases; installing items in DIY projects; repairing everyday items and toys; filling agents used in dental treatment; and bonding and decorating artificial nails. Furthermore, the first composition can be used in the production and repair of items such as shelves, metal racks, boxes, plastic models, miniatures, and accessories, thereby improving the workability, precision, and quality of the production and repair work.

[0065] As a method for storing the first composition, a known method can be appropriately adopted. Considering that the first composition has moisture curing properties and photocuring properties, the first composition is preferably stored in an environment with low humidity and oxygen (for example, moisture and oxygen each being 0.01% by volume or less) and in a light-shielded state.

[0066] <2-Cyanoacrylate Composition> The 2-cyanoacrylate composition (hereinafter also referred to as the "second composition") of the present disclosure is used in producing a photocurable adhesive composition and is a composition for photocurable adhesives containing the 2-cyanoacrylate compound described above. The second composition also contains an acidic phosphate ester compound. In the second composition, the phosphorus content derived from the acidic phosphate ester compound is greater than 0 ppm by mass and not more than 30 ppm by mass. Specific examples of the 2-cyanoacrylate compound and the acidic phosphate ester compound, as well as preferred content ranges, are as described for the first composition. The second composition is advantageous in that its use as a material for producing a photocurable adhesive composition containing a Group 8 transition metal metallocene compound and a photoradical generator together with the 2-cyanoacrylate compound can suppress deterioration of the photocurability of the photocurable adhesive composition over time.

[0067] The present disclosure will be specifically described below based on examples. However, the present disclosure is not limited to these examples. In the following, "parts" and "%" mean "parts by mass" and "% by mass", respectively, unless otherwise specified.

[0068] <Production of 2-cyanoacrylate compound [1]> (Production Example 1) A condensate obtained by a dehydration condensation reaction of ethyl cyanoacetate and formaldehyde was depolymerized using diphosphorus pentoxide as a depolymerization catalyst (catalyst concentration relative to the condensate was 13 g / L) to obtain crude ethyl 2-cyanoacrylate. Subsequently, distillation using a rectification column was performed once to obtain ethyl 2-cyanoacrylate (referred to as (M-1)). The phosphorus content derived from acidic phosphate ester compounds (i.e., monoethyl phosphate and diethyl phosphate) in ethyl 2-cyanoacrylate (M-1) was measured by ICP atomic emission spectroscopy, and the content of acidic phosphate ester compounds in ethyl 2-cyanoacrylate (M-1) was measured by gas chromatography. As a result, both the phosphorus content and the acidic phosphate ester compound content were below the detection limits of the measuring device (5 ppm by mass, 20 ppm by mass).

[0069] Details of the measurement method are as follows. [Measurement of phosphorus content by ICP atomic emission spectroscopy] 1 g of sample was placed in a 100 mL quartz beaker, 4 mL of sulfuric acid was added, and the mixture was heated on a hot plate at 180 to 250°C to carbonize. Nitric acid and hydrogen peroxide solution were added in small amounts and heated repeatedly to decompose the carbonized material and dry it. After cooling to room temperature, 1 mL of nitric acid and 10 mL of ultrapure water were added, and the mixture was heated on a hot plate at 200°C for 15 minutes. After cooling to room temperature, the liquid was transferred to a 20 mL PFA (perfluoroalkoxyalkane) container and diluted to a total volume of 20 g with ultrapure water to prepare the test solution. The test solution was measured using an ICP mass spectrometer, and the phosphorus content was determined using the calibration curve method. Pretreatment environment: Clean room G (class 1000) and clean draft (class 100) Sulfuric acid, nitric acid: ultra-high purity reagent ULtrapur-100 (Kanto Chemical) Hydrogen peroxide solution: electronics industry grade (Kishida Chemical) ICP mass spectrometer: Spectro ARCOS SOP [Measurement of acidic phosphate ester compound content by gas chromatography] Gas chromatography measurement conditions Apparatus: Hitachi G-5000 model (FPD detector) Column: SPB-5 (Supelco) length 60 m, inner diameter 0.53 mm, film thickness 0.5 μm Temperature conditions: 120°C (5 min) -10°C / min -220°C -70°C / min -280°C (10 min) Injection port temperature: 300°C, detector temperature: 300°C Carrier gas: helium 110 kPa Internal standard substance: tri-n-butyl phosphate Sample preparation method: 0.5 g of sample was weighed out, 1 mL of a 99 / 1 (v / v) acetonitrile / acetic acid solution was added, and 10 μL of a 250 μg / mL tri-n-butyl phosphate standard solution was added as an internal standard using a microsyringe. 100 μL of acetonitrile was added to 20 μL of this mixture, followed by 50 μL of a 100 / 1 (v / v) N,O-bis(trimethylsilyl)trifluoroacetamide / trimethylchlorosilane solution, and the mixture was allowed to react at 90°C for 30 minutes. After allowing to cool, 1 μL of this solution was sampled and subjected to gas chromatography under the above conditions.

[0070] Production Example 2 Ethyl-2-cyanoacrylate (M-2) was obtained by adding 40 ppm by mass of a mixture of monoethyl phosphate and diethyl phosphate to ethyl-2-cyanoacrylate (M-1).

[0071] Comparative Production Examples 1 and 2 Ethyl-2-cyanoacrylates (M-3) and (M-4) were obtained by the same procedure as in Production Example 2, except that the amount of the mixture of monoethyl phosphate and diethyl phosphate added to ethyl-2-cyanoacrylate (M-1) was changed to 190 ppm by mass and 420 ppm by mass, respectively. The phosphorus content derived from the acidic phosphate ester compound and the acidic phosphate ester compound content in ethyl-2-cyanoacrylates (M-3) and (M-4) were measured, and the results are shown in Table 1.

[0072] Comparative Production Example 3 Crude ethyl 2-cyanoacrylate was obtained by the same procedure as in Production Example 1, and then simple distillation was carried out once to obtain ethyl 2-cyanoacrylate (M-5). The phosphorus content derived from the acidic phosphate ester compound and the acidic phosphate ester compound content in ethyl 2-cyanoacrylate (M-5) were measured, and the results are shown in Table 1.

[0073]

[0074] <Preparation and Evaluation of Photocurable Adhesive Composition [1]> (Example 1) (1) Preparation of Photocurable Adhesive Composition 84.9 parts by mass of ethyl-2-cyanoacrylate (M-1), ferrocene (FeCp) as a Group 8 transition metal metallocene compound (synergist), ２ ) as a photoradical generator, and 0.08 parts by mass of bis(4-methoxybenzoyl)diethylgermanium (a compound represented by the following formula) as a photoradical generator were mixed to prepare a photocurable adhesive composition (B-1). For the photocurable adhesive composition (B-1) obtained, the phosphorus content derived from the acidic phosphate ester compound in the photocurable adhesive composition was calculated from the phosphorus content derived from the acidic phosphate ester compound in the ethyl-2-cyanoacrylate (M-1) (measured by ICP atomic emission spectroscopy). The results are shown in Table 2.

[0075]

[0076] (2) Evaluation of photocurability The photocurable adhesive composition (B-1) was left at room temperature for 1 day in a light-shielded state, shielded from the outside air. Thereafter, a mold was placed on a glass slide, and the photocurable adhesive composition (B-1) was applied to a thickness of 1 mm. The photocurable adhesive composition (B-1) on the glass slide was subjected to a 405 nm wavelength, 20 mW / cm illuminance test. ２ The photocurability was evaluated according to the following criteria. The results are shown in Table 2. ○: Cured within 10 seconds after irradiation. △: Not cured within 10 seconds after irradiation, but cured within 30 seconds. ×: Not cured within 30 seconds after irradiation.

[0077] Example 2 and Comparative Examples 1 to 3 Photocurable adhesive compositions (B-2) to (B-5) were prepared in the same manner as in Example 1, except that the type of 2-cyanoacrylate compound was changed as shown in Table 2 below. Furthermore, photocurability was evaluated in the same manner as in Example 1 using the prepared photocurable adhesive compositions. The results are shown in Table 2. Table 2 also shows the phosphorus content derived from the acidic phosphate ester compound in the photocurable adhesive composition. For Example 2 and Comparative Examples 1 and 2, the phosphorus content derived from the acidic phosphate ester compound in the composition was calculated from the phosphorus content derived from the acidic phosphate ester compound in ethyl-2-cyanoacrylate (M-1) (measured by ICP atomic emission spectroscopy) and the amount of the mixture of monoethyl phosphate and diethyl phosphate added. For Comparative Example 3, the phosphorus content derived from the acidic phosphate ester compound in the photocurable adhesive composition was calculated from the phosphorus content derived from the acidic phosphate ester compound in ethyl-2-cyanoacrylate (M-5) (measured by ICP atomic emission spectroscopy).

[0078]

[0079] As shown in Table 2, the photocurable adhesive compositions of Examples 1 and 2 had better photocurability than those of Comparative Examples 1 to 3. In particular, the photocurable adhesive composition of Example 1 rapidly cured within 10 seconds after light irradiation. These results demonstrate that the 2-cyanoacrylate compound and / or the acidic phosphate ester compound in the photocurable adhesive composition affect the change over time in the photocurability of the photocurable adhesive composition, and that reducing the amount of the acidic phosphate ester compound is important for maintaining good photocurability over a long period of time.

[0080] <Production of 2-cyanoacrylate compound [2]> (Production Examples 3 and 4) A condensate obtained by a dehydration condensation reaction of ethoxyethyl-2-cyanoacetate and formaldehyde was depolymerized using diphosphorus pentoxide as a depolymerization catalyst (catalyst concentration relative to the condensate was 13 g / L) to obtain crude ethoxyethyl-2-cyanoacrylate. Subsequently, simple distillation was performed twice, and the distillate from the second run was divided into two parts, the first half and the second half, to obtain ethoxyethyl-2-cyanoacrylate. The second half of the second distillate was designated (M-6), and the first half was designated (M-7). The phosphorus contents derived from acidic phosphate ester compounds (i.e., monoethoxyethyl phosphate and diethoxyethyl phosphate) in the ethoxyethyl-2-cyanoacrylates (M-6) and (M-7) were measured by ICP atomic emission spectroscopy in the same manner as in Production Example 1. The contents of acidic phosphate ester compounds in ethoxyethyl-2-cyanoacrylate (M-6) and (M-7) were calculated from the phosphorus content. The results of measuring the phosphorus content derived from acidic phosphate ester compounds and the acidic phosphate ester compound content in ethoxyethyl-2-cyanoacrylate (M-6) and (M-7) are shown in Table 3.

[0081]

[0082] <Preparation and Evaluation of Photocurable Adhesive Compositions [2]> (Examples 3 and 4) Photocurable adhesive compositions (B-6) and (B-7) were prepared in the same manner as in Example 1, except that the type of 2-cyanoacrylate compound was changed as shown in Table 4 below. The photocurable adhesive compositions prepared were then used to evaluate photocurability in the same manner as in Example 1. The results are shown in Table 4. Table 4 also shows the phosphorus content derived from the acidic phosphate ester compound in the photocurable adhesive composition. The phosphorus content derived from the acidic phosphate ester compound in the composition was calculated from the phosphorus content (measured by ICP atomic emission spectroscopy).

[0083]

[0084] As shown in Table 4, the photocurable adhesive compositions of Examples 3 and 4 had good photocurability. In particular, the photocurable adhesive composition of Example 3 rapidly cured in about 5 seconds after light irradiation. These results also indicate that the 2-cyanoacrylate compound and / or the acidic phosphate ester compound in the photocurable adhesive composition affect the change over time in the photocurability of the photocurable adhesive composition, and that reducing the amount of the acidic phosphate ester compound is important for maintaining good photocurability over a long period of time.

[0085] The present invention is not limited to the above-described embodiments, and encompasses various modifications and equivalent modifications within the scope of the spirit of the present invention. Therefore, in light of the above teachings, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are to be understood as falling within the scope and spirit of the present invention.

Claims

1. A photocurable adhesive composition comprising: a 2-cyanoacrylate compound having a phosphorus content derived from an acidic phosphate ester compound of 30 mass ppm or less; a Group 8 transition metal metallocene compound; and a photoradical generator.

2. The photocurable adhesive composition according to claim 1, wherein the content of the acidic phosphate ester compound in the 2-cyanoacrylate compound is 150 ppm by mass or less.

3. A photocurable adhesive composition according to claim 1, wherein the phosphorus content derived from the acidic phosphate ester compound in the composition is 30 ppm by mass or less.

4. A photocurable adhesive composition comprising: a 2-cyanoacrylate compound having an acidic phosphate compound content of 150 ppm by mass or less; a Group 8 transition metal metallocene compound; and a photoradical generator.

5. A photocurable adhesive composition comprising a 2-cyanoacrylate compound, a Group 8 transition metal metallocene compound, and a photoradical generator, wherein the phosphorus content derived from the acidic phosphate ester compound is 30 ppm by mass or less.

6. A photocurable adhesive composition according to any one of claims 1 to 5, wherein the photoradical generator is at least one selected from the group consisting of acylgermane compounds and acylphosphine oxide compounds.

7. A photocurable adhesive composition according to any one of claims 1 to 5, wherein the acidic phosphate ester compound is at least one selected from the group consisting of a phosphate monoester compound and a phosphate diester compound.

8. A bonded body in which adherends are bonded to each other with the photocurable adhesive composition according to any one of claims 1 to 5.

9. A 2-cyanoacrylate composition for photocurable adhesives used in the manufacture of a photocurable adhesive composition containing a 2-cyanoacrylate compound, the composition containing an acidic phosphate ester compound, and having a phosphorus content derived from the acidic phosphate ester compound of more than 0 ppm by mass and not more than 30 ppm by mass.

10. The 2-cyanoacrylate composition for photocurable adhesives according to claim 9, wherein the photocurable adhesive composition contains a Group 8 transition metal metallocene compound and a photoradical generator.

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