2-Cyanoacrylate adhesive composition

Abstract

To provide a 2-cyanoacrylate-based adhesive composition that has excellent adhesive strength to metals such as aluminum and copper.SOLUTION: Provided is a 2-cyanoacrylate-based adhesive composition, which is an adhesive composition containing a 2-cyanoacrylate compound, and a compound of (1) a carboxylic acid with a cyano group at the α-position having a particular structure represented by 1-cyano-1-cyclopropanecarboxylic acid or (2) a carboxylic acid with an oxo group at the α-position having a particular structure represented by pyruvic acid, and in which the carboxylic acid compound is contained in an amount sufficient to have a higher adhesive strength to the aluminum substrate measured in accordance with JIS K 6849 than the adhesive composition excluding the carboxylic acid compound.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a 2-cyanoacrylate adhesive composition that has excellent adhesive strength to metals such as copper and aluminum. [Background technology]

[0002] 2-cyanoacrylate adhesive compositions, due to the unique anionic polymerization property of the main component 2-cyanoacrylate, initiate polymerization with weak anions such as traces of moisture adhering to the surface of the adherend, and can firmly bond various materials in a short time. For this reason, they are widely used as so-called instant adhesives in various industries such as electronics, electrical and automotive, leisure fields and ordinary households.

[0003] In recent years, 2-cyanoacrylate adhesive compositions have been used in the production of electric and electronic parts containing metal wiring, such as printed wiring boards and wire harnesses, and there is a demand for improved adhesion to metals. Patent Documents 1 to 3 disclose adhesive compositions that exhibit excellent adhesion speed to metals and thermoplastic elastomers with low polarity, as well as excellent appearance and storage stability of the cured product, by blending an onium salt having a specific structure with a 2-cyanoacrylate compound.

[0004] However, in recent years, there has been a demand for further improvement in the adhesion, particularly adhesive strength, of 2-cyanoacrylate adhesive compositions to metals, particularly to copper and aluminum used in the production of electric and electronic components.

[0005] Patent Document 4 proposes an impregnation composition that exhibits excellent impregnation and curing properties for wood-based materials and foamed materials by blending a 2-cyanoacrylate compound with a 2-cyanoacrylate-soluble carboxylic acid having a pKa of 1.2 to 4.0 and an anionic polymerization accelerator. However, this document only examines the improvement of the curing speed and does not disclose any improvement in adhesive strength, much less any improvement in adhesive strength to metals such as copper and aluminum. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2014 / 042082 [Patent Document 2] International Publication No. 2015 / 137156 [Patent Document 3] International Publication No. 2018 / 003682 [Patent Document 4] JP 2000-53924 A Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a 2-cyanoacrylate adhesive composition which has excellent adhesive strength to metals such as aluminum and copper and is suitable for the production of electric / electronic components and the like which include wiring of such metals. [Means for solving the problem]

[0008] The present inventors discovered that by adding a specific carboxylic acid compound to a 2-cyanoacrylate compound, a 2-cyanoacrylate adhesive composition having superior adhesive strength to metals such as aluminum and copper compared to conventional compositions can be obtained, and thus completed the present invention.

[0009] According to one aspect of the present invention, there is provided an adhesive composition comprising: The composition contains a 2-cyanoacrylate compound and at least one carboxylic acid compound selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2), The present invention provides a 2-cyanoacrylate adhesive composition containing the carboxylic acid compound in an amount sufficient to provide an adhesive strength to an aluminum substrate, measured in accordance with JIS K 6849, that is higher than that of an adhesive composition obtained by excluding the carboxylic acid compound.

[0010] [ka] (In formula (1), n ​​represents an integer of 1 or 2; each R1 independently represents a hydrogen atom or a hydrocarbon group having 1 to 13 carbon atoms; the bond a may be a single bond or a double bond; and two R1 may be bonded to each other to form a cyclic hydrocarbon group.)

[0011] [ka] (In formula (2), R2 represents a hydrocarbon group having 1 to 10 carbon atoms.)

[0012] According to a preferred embodiment of the present invention, the adhesive composition of the present invention contains the carboxylic acid compound in an amount sufficient to ensure that the adhesive strength to an aluminum substrate, measured in accordance with JIS K 6849, is at least 15% higher than that of an adhesive composition obtained by excluding the carboxylic acid compound from the adhesive composition. According to a further preferred embodiment of the present invention, the adhesive composition of the present invention contains the carboxylic acid compound in an amount sufficient to ensure that the adhesive strength to a copper substrate, measured in accordance with JIS K 6849, is at least 10% higher than that of an adhesive composition obtained by excluding the carboxylic acid compound from the adhesive composition.

[0013] According to another preferred embodiment of the present invention, the adhesive composition of the present invention contains the carboxylic acid compound in an amount of 80 ppm or more relative to 100 parts by mass of the 2-cyanoacrylate compound. According to another preferred embodiment of the present invention, the adhesive composition of the present invention contains the carboxylic acid compound in an amount of 6000 ppm or less per 100 parts by mass of the 2-cyanoacrylate compound.

[0014] According to another preferred embodiment of the present invention, R1 in the formula (1) is each independently a hydrogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, an allyl group, or an aryl group, or two R1 are bonded to each other to form a cyclic hydrocarbon group. According to another preferred embodiment of the present invention, R2 in the formula (2) is a linear or branched alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, an allyl group, or an aryl group.

[0015] According to another aspect, the present invention provides a bonded article comprising at least a first metal part and a second metal part bonded thereto, the first part and the second part being bonded together via an adhesive, wherein the adhesive is the 2-cyanoacrylate-based adhesive composition of the present invention described above.

[0016] According to yet another aspect, the present invention provides a method for producing a bonded article, which comprises bonding two parts, at least one of which is made of metal, via the above-mentioned 2-cyanoacrylate adhesive composition of the present invention.

[0017] According to yet another aspect, the present invention provides an agent for improving the adhesive strength of a 2-cyanoacrylate adhesive composition to metal, comprising at least one carboxylic acid compound selected from the group consisting of compounds represented by the above formula (1) and compounds represented by the above formula (2).

[0018] According to still another aspect, the present invention provides a method for improving the adhesive strength of a 2-cyanoacrylate adhesive composition, comprising adding to the 2-cyanoacrylate adhesive composition at least one carboxylic acid compound selected from the group consisting of the compounds represented by formula (1) above and the compounds represented by formula (2) above in an amount sufficient to increase the adhesive strength of the adhesive composition to an aluminum substrate, as measured in accordance with JIS K 6849. Effect of the Invention

[0019] According to the present invention, at least one carboxylic acid compound selected from the group consisting of the compounds represented by the above formula (1) and the compounds represented by the above formula (2) is blended with a 2-cyanoacrylate compound, thereby obtaining a 2-cyanoacrylate adhesive composition having superior adhesive strength to metals such as aluminum and copper compared to conventional compositions. Furthermore, according to the present invention, it has been made clear that a similar carboxylic acid compound can be used to improve the adhesive strength of an existing 2-cyanoacrylate adhesive composition to metals. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described, but the present invention is not limited thereto.

[0021] 1. 2-Cyanoacrylate compounds The 2-cyanoacrylate adhesive composition of the present invention contains a 2-cyanoacrylate compound as the main adhesive component. The 2-cyanoacrylate compound used in the present invention is not particularly limited as long as it can be used as an adhesive component, and examples thereof include alkyl-2-cyanoacrylate and 2-cyanoacrylate having an ether bond in the ester residue.

[0022] 1-1. Alkyl-2-cyanoacrylate Various alkyl-2-cyanoacrylates can be used. The upper limit of the number of carbon atoms in the alkyl group corresponding to the ester residue of the alkyl-2-cyanoacrylate is not particularly limited, but can be, for example, 12 or less, and preferably 7 or less. Specific examples of alkyl-2-cyanoacrylates include methyl-2-cyanoacrylate, ethyl-2-cyanoacrylate, n-propyl-2-cyanoacrylate, isopropyl-2-cyanoacrylate, n-butyl-2-cyanoacrylate, sec-butyl-2-cyanoacrylate, isobutyl-2-cyanoacrylate (2-methylpropyl-2-cyanoacrylate), n-pentyl-2-cyanoacrylate, n-hexyl-2-cyanoacrylate, n-hexyl-2-cyanoacrylate, and n-hexyl-2-cyanoacrylate. butyl-2-cyanoacrylate, 1-methylpentyl-2-cyanoacrylate, n-octyl-2-cyanoacrylate, 2-octyl-2-cyanoacrylate, 2-ethylhexyl-2-cyanoacrylate, n-nonyl-2-cyanoacrylate, isononyl-2-cyanoacrylate, n-decyl-2-cyanoacrylate, isodecyl-2-cyanoacrylate, n-undecyl-2-cyanoacrylate, n-dodecyl-2-cyanoacrylate, etc. These may be used alone or in combination of two or more.

[0023] Among these, alkyl-2-cyanoacrylates having an alkyl group with 1 to 6 carbon atoms are preferred, and specific examples thereof include at least one compound selected from the group consisting of methyl-2-cyanoacrylate, ethyl-2-cyanoacrylate, n-propyl-2-cyanoacrylate, isopropyl-2-cyanoacrylate, n-butyl-2-cyanoacrylate, sec-butyl-2-cyanoacrylate, isobutyl-2-cyanoacrylate, n-pentyl-2-cyanoacrylate, and n-hexyl-2-cyanoacrylate. When alkyl-2-cyanoacrylates having an alkyl group with 2 to 6 carbon atoms are included, the heat resistance of the resulting cured product is improved, which is preferable, and at least one selected from the group consisting of alkyl-2-cyanoacrylates having an alkyl group with 2 or 3 carbon atoms and n-butyl-2-cyanoacrylate is more preferred in terms of obtaining higher adhesive strength.

[0024] 1-2. 2-Cyanoacrylate with an ether bond in the ester residue Examples of 2-cyanoacrylates having an ether bond in the ester residue include alkoxyalkyl-2-cyanoacrylates and cyclic alkyl ether 2-cyanoacrylates. In the present invention, the "ester residue" refers to the portion of the compound other than the ester bond, i.e., the portion represented by -R in the group represented by -CO-OR that is ester-bonded to 2-cyanoacrylate.

[0025] As the alkoxyalkyl-2-cyanoacrylate, the alkoxyalkyl group preferably has 2 to 12 carbon atoms, more preferably has 2 to 10 carbon atoms, and even more preferably has 2 to 8 carbon atoms. Specific examples of alkoxyalkyl-2-cyanoacrylates include methoxyethyl-2-cyanoacrylate, ethoxyethyl-2-cyanoacrylate, propoxyethyl-2-cyanoacrylate, isopropoxyethyl-2-cyanoacrylate, butoxyethyl-2-cyanoacrylate, hexyloxyethyl-2-cyanoacrylate, 2-ethylhexyloxyethyl-2-cyanoacrylate, butoxyethoxyethyl-2-cyanoacrylate, hexyloxyethoxyethyl-2-cyanoacrylate, 2-ethylhexyloxyethoxyethyl-2-cyanoacrylate, methoxypropyl-2-cyanoacrylate, methoxypropoxypropyl-2-cyanoacrylate, methoxypropoxypropoxypropyl-2-cyanoacrylate, ethoxypropyl-2-cyanoacrylate, and ethoxypropoxypropyl-2-cyanoacrylate. A specific example of the cyclic alkyl ether 2-cyanoacrylate is tetrahydrofurfuryl-2-cyanoacrylate. The 2-cyanoacrylate having an ether bond in the ester residue may be used alone or in combination of two or more kinds.

[0026] Among these, alkoxyethyl-2-cyanoacrylates having an alkoxy group with 1 to 8 carbon atoms, such as methoxyethyl-2-cyanoacrylate, ethoxyethyl-2-cyanoacrylate, and butoxyethyl-2-cyanoacrylate, are preferably used because they are easily available and have excellent stability, and ethoxyethyl-2-cyanoacrylate is particularly preferred.

[0027] 1-3. Other 2-cyanoacrylate compounds Other usable 2-cyanoacrylate compounds include cyclohexyl-2-cyanoacrylate, phenyl-2-cyanoacrylate, chloroethyl-2-cyanoacrylate, allyl-2-cyanoacrylate, propargyl-2-cyanoacrylate, benzyl-2-cyanoacrylate, 2,2,2-trifluoroethyl-2-cyanoacrylate, hexafluoroisopropyl-2-cyanoacrylate, etc. These compounds may be used alone or in combination of two or more.

[0028] 2. Carboxylic acid compounds The 2-cyanoacrylate adhesive composition of the present invention contains at least one carboxylic acid compound selected from the group consisting of the compounds represented by the above formula (1) and the compounds represented by the above formula (2).

[0029] Specific examples of the compound represented by the above formula (1) include cyanoacrylic acid (2-cyanopropenoic acid), cyanoacetic acid, 2-cyanopropionic acid, 2-cyanobutanoic acid, 2-cyanopentanoic acid, 2-cyanohexanoic acid, 2-cyanoheptanoic acid, 2-cyanooctanoic acid, 2-cyanononanoic acid, 2-cyanodecanoic acid, 2-cyanododecanoic acid, 2-cyano-2-cyclohexylideneacetic acid, 2-cyano-2-cycloheptylacetic acid, 2-cyano-3-phenylpropionic acid, 2-cyano-3,3-diphenylacrylic acid, and 2-cyano-3-methyl-2-butenoic acid.

[0030] Among the compounds represented by the above formula (1), specific examples of compounds in which two R1 are bonded to each other to form a cyclic hydrocarbon group include compounds in which two R1 are bonded to each other to form a cyclic hydrocarbon group having 3 to 6 carbon atoms, such as 1-cyano-1-cyclopropanecarboxylic acid, 1-cyano-1-cyclobutanecarboxylic acid, 1-cyano-1-cyclopentanecarboxylic acid, and 1-cyano-1-cyclohexanecarboxylic acid.

[0031] Among these compounds, compounds in which R1 in the formula (1) is each independently a hydrogen atom, a linear or side-chain alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, an allyl group, or an aryl group, or two R1 are bonded to each other to form a cyclic hydrocarbon group are preferred, and cyanoacrylic acid represented by the following formula (1-1), cyanoacetic acid represented by the following formula (1-2), and 1-cyano-1-cyclopropanecarboxylic acid represented by the following formula (1-3) are more preferred, since they improve adhesion to metals even when added in an extremely small amount.

[0032] [ka]

[0033] [ka]

[0034] [ka]

[0035] Specific examples of the compound represented by the above formula (2) include pyruvic acid (2-oxopropanoic acid), 2-oxobutyric acid (2-oxobutanoic acid), 2-oxovaleric acid (2-oxopentanoic acid), α-ketoisovaleric acid (3-methyl-2-oxobutanoic acid), 4-methyl-2-oxovaleric acid (4-methyl-2-oxopentanoic acid), 3-methyl-2-oxovaleric acid (3-methyl-2-oxopentanoic acid), phenylglyoxylic acid, 2-cyclohexyl-2-oxoacetic acid, and 2-oxo-4-phenyl-3-butenoic acid. Among these compounds, preferred are compounds in which R2 in the formula (2) is a linear or side-chain alkyl group, cycloalkyl group, allyl group, or aryl group having 1 to 10 carbon atoms, and more preferred is pyruvic acid represented by the following formula (2-1), since the addition of an extremely small amount of the compound improves adhesion to metals.

[0036] [ka]

[0037] 3. 2-Cyanoacrylate adhesive composition The present invention is based on the discovery that when a 2-cyanoacrylate compound contains a specific carboxylic acid compound, the adhesion to metals such as aluminum and copper is significantly improved compared to when the 2-cyanoacrylate compound does not contain the carboxylic acid compound. Therefore, according to the present invention, the content of the carboxylic acid compound is set to an amount sufficient to make the adhesive strength to an aluminum substrate, measured in accordance with JIS K 6849, higher than that in the case where the carboxylic acid compound is not added.

[0038] Preferably, the content of the carboxylic acid compound in the adhesive composition of the present invention is an amount that provides a significant improvement in the adhesion of the 2-cyanoacrylate compound to aluminum substrates and / or copper substrates. In the present invention, a "significantly improving effect on adhesion" means, in the case of adhesion to aluminum substrates, that the adhesive strength to aluminum substrates, measured in accordance with JIS K 6849, is preferably 15% or more, more preferably 17% or more, and even more preferably 20% or more higher than that of an adhesive composition excluding the carboxylic acid compound, and in the case of adhesion to copper substrates, that the adhesive strength to copper substrates, measured in accordance with JIS K 6849, is preferably 10% or more, more preferably 11% or more, and even more preferably 15% or more higher than that of an adhesive composition excluding the carboxylic acid compound.

[0039] The appropriate content of the carboxylic acid compound in the adhesive composition of the present invention varies depending on the types of 2-cyanoacrylate compound and carboxylic acid compound, but it is preferable to set the lower limit of the content as a value that provides the above-mentioned "significant improvement effect in adhesion." The lower limit of the above content is usually 80 ppm or more, preferably 200 ppm or more, more preferably 300 ppm or more, even more preferably 500 ppm or more, even more preferably 1200 ppm or more, and particularly preferably 2100 ppm or more, relative to 100 parts by mass of the 2-cyanoacrylate compound. The upper limit of the content is not particularly limited as long as it is an amount that does not impair the practicality or economical efficiency of the adhesive of the present invention, and is preferably 6000 ppm or less. The content of the carboxylic acid compound in the adhesive composition of the present invention can be measured, for example, by liquid chromatography.

[0040] The 2-cyanoacrylate compound used in the present invention preferably has a purity of 99% or more, more preferably 99.5% or more. If the purity of the 2-cyanoacrylate is 99% or more, it is preferable because it has excellent instantaneous adhesion, storage stability, and adhesive heat resistance.

[0041] In order to improve storage stability, the 2-cyanoacrylate adhesive composition of the present invention may contain an anionic polymerization inhibitor such as sulfur dioxide, paratoluenesulfonic acid, methanesulfonic acid, propanesultone, or boron trifluoride complex, or a radical polymerization inhibitor such as hydroquinone, catechol, or pyrogallol. In addition, in order to improve adhesion speed, a curing accelerator such as polyethylene glycol derivatives, crown ether, or calixarene may be added. Furthermore, thickeners, plasticizers, fillers, elastomers, thixotropic agents, adhesion agents, crosslinking agents, dyes, fragrances, and the like may be added depending on the purpose. The amount of these additives added may be appropriately selected within a range that does not impair the effect of improving adhesive strength by adding the carboxylic acid compound of the present invention and the practicality or economics of the adhesive of the present invention.

[0042] 4. Joints and their manufacturing methods The 2-cyanoacrylate adhesive composition of the present invention has excellent adhesive strength to metals, and can be suitably used as an adhesive for bonding two parts, at least one of which is made of metal, in a manufacturing method for bonding the two parts. Therefore, according to the present invention, a bonded product can be manufactured that includes at least a first part made of metal and a second part bonded thereto, and the first part and the second part are bonded via the 2-cyanoacrylate adhesive composition of the present invention. In this case, the 2-cyanoacrylate adhesive composition of the present invention may be directly bonded to the metal surface of the first part, or may be bonded to a metal surface that has been previously treated with a primer. The metal constituting the first part is preferably aluminum or copper. The material of the second part is not particularly limited and can be appropriately selected from metal, plastic, rubber, wood, concrete, etc.

[0043] The bonded article of the present invention may, for example, be a laminate in which two sheet-like parts are superimposed and bonded together, or a laminate in which a linear part is covered with another part and bonded together. For example, the bonded article may be an article in which a metal part is attached to a resin molded article. More specifically, the bonded article may include a printed wiring board and a laminate thereof, a fire harness, a connector, a coated electric wire, etc. EXAMPLES

[0044] The present invention will be specifically described below based on examples. Note that the present invention is not limited to these examples. In the following, "parts" and "%" mean "parts by mass" and "% by mass", respectively, unless otherwise specified.

[0045] Examples 1 to 13 and Comparative Examples 1 to 4 The components shown in Table 1 were mixed in the proportions shown in Table 1 by a conventional method to prepare adhesive compositions, which were then evaluated as described below.

[0046] evaluation The tensile adhesive strength of the obtained adhesive composition to an aluminum substrate and a copper substrate at room temperature was measured in accordance with JIS K 6861. The increase rate of adhesive strength was also calculated relative to a comparative example not containing a carboxylic acid compound. The results are shown in Table 1.

[0047] [Table 1]

[0048] As shown in Table 1, in the case of Examples 1 to 13, which contained a carboxylic acid compound, the adhesive strength to the aluminum substrate showed an increase of 15% or more compared to the comparative example, and the adhesive strength to the copper substrate showed an increase of 10% or more compared to the comparative example. [Industrial Applicability]

[0049] The 2-cyanoacrylate adhesive composition of the present invention has excellent adhesive strength to metals such as aluminum and copper, and is therefore suitable for the manufacture of electrical and electronic components that include metal wiring, and can also be widely used in other industrial fields where metal is used as an adherend.

Claims

1. 1. An adhesive composition comprising: The composition contains at least one 2-cyanoacrylate compound selected from the group consisting of alkyl-2-cyanoacrylate having an alkyl group having 2 or 3 carbon atoms, n-butyl-2-cyanoacrylate, methoxyethyl-2-cyanoacrylate, ethoxyethyl-2-cyanoacrylate, and butoxyethyl-2-cyanoacrylate, and at least one carboxylic acid compound selected from the group consisting of compounds represented by the following formula (1): The 2-cyanoacrylate adhesive composition contains the carboxylic acid compound in an amount of 80 ppm or more and 6000 ppm or less relative to 100 parts by mass of the 2-cyanoacrylate compound. 【Chemistry 1】 (In formula (1), n ​​represents an integer of 1 to 2, and R １ each independently represents a hydrogen atom or a hydrocarbon group having 1 to 13 carbon atoms (except when all of R 1 are hydrogen atoms), the bond a may be a single bond or a double bond, and two R １ may be bonded to each other to form a cyclic hydrocarbon group.

2. R in the formula (1) １ are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, an allyl group, or an aryl group (excluding the case where all of R 1 are hydrogen atoms), １ The 2-cyanoacrylate adhesive composition according to claim 1, wherein are bonded to each other to form a cyclic hydrocarbon group.

3. A bonded article comprising at least a first metal component and a second metal component bonded thereto, the first metal component and the second metal component being bonded together via an adhesive, the adhesive being the 2-cyanoacrylate adhesive composition according to claim 1 or 2.

4. A method for producing a bonded article, comprising bonding two parts, at least one of which is made of metal, via the 2-cyanoacrylate adhesive composition according to claim 1 or 2.

5. 1. An agent for improving the adhesive strength of a 2-cyanoacrylate adhesive composition to metal, comprising at least one carboxylic acid compound selected from the group consisting of compounds represented by the following formula (1): wherein the 2-cyanoacrylate adhesive composition comprises at least one 2-cyanoacrylate compound selected from the group consisting of alkyl-2-cyanoacrylate having an alkyl group having 2 or 3 carbon atoms, n-butyl-2-cyanoacrylate, methoxyethyl-2-cyanoacrylate, ethoxyethyl-2-cyanoacrylate, and butoxyethyl-2-cyanoacrylate, and the carboxylic acid compound is prepared so as to be added in an amount of 80 ppm or more and 6000 ppm or less relative to 100 parts by mass of the 2-cyanoacrylate compound: 【Chemistry 3】 (In formula (1), n ​​represents an integer of 1 to 2, and R １ each independently represents a hydrogen atom or a hydrocarbon group having 1 to 13 carbon atoms (except when all of R 1 are hydrogen atoms), the bond a may be a single bond or a double bond, and two R １ may be bonded to each other to form a cyclic hydrocarbon group.

6. A method for improving the adhesive strength of a 2-cyanoacrylate adhesive composition, comprising adding to the 2-cyanoacrylate adhesive composition containing at least one 2-cyanoacrylate compound selected from the group consisting of alkyl-2-cyanoacrylate having an alkyl group having 2 or 3 carbon atoms, n-butyl-2-cyanoacrylate, methoxyethyl-2-cyanoacrylate, ethoxyethyl-2-cyanoacrylate, and butoxyethyl-2-cyanoacrylate, at least one carboxylic acid compound selected from the group consisting of compounds represented by the following formula (1) in an amount of 80 ppm to 6,000 ppm per 100 parts by mass of the 2-cyanoacrylate compound: 【Chemistry 5】 (In formula (1), n ​​represents an integer of 1 to 2, and R １ each independently represents a hydrogen atom or a hydrocarbon group having 1 to 13 carbon atoms (except when all of R 1 are hydrogen atoms), the bond a may be a single bond or a double bond, and two R １ may be bonded to each other to form a cyclic hydrocarbon group.

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