2-Cyanoacrylate adhesive composition

Abstract

The present invention provides a 2-cyanoacrylate adhesive composition that can achieve both shear bonding strength and flexibility of the cured product. [Solution] A 2-cyanoacrylate adhesive composition containing a 2-cyanoacrylate compound (A) represented by general formula (1) and a 2-cyanoacrylate compound (B) which includes methyl-2-cyanoacrylate, ethyl-2-cyanoacrylate, propyl-2-cyanoacrylate, etc. However, in general formula (1), L is independently -CH2CH2-, -CH2CH2CH2-, and -CH(R 1 )CH2- or -CH2CH(R 1 )- represents R 1 R represents a linear or branched alkyl group having 1 to 6 carbon atoms, which may have substituents. 2 represents a linear or branched alkyl group having 1 to 8 carbon atoms, which may have substituents. TIFF2026114189000009.tif40170

Description

[Technical Field]

[0001] This invention relates to a 2-cyanoacrylate-based adhesive composition. [Background technology]

[0002] 2-cyanoacrylate adhesive compositions, which primarily use 2-cyanoacrylate compounds as their adhesive component, initiate polymerization upon contact with even small amounts of moisture on the adherend surface, enabling them to firmly bond various materials in a short time. Therefore, 2-cyanoacrylate adhesive compositions are widely used as so-called instant adhesives in industrial, medical, and household applications.

[0003] For example, Patent Document 1 contains a 2-cyanoacrylate compound and a polyfunctional cyanoacrylate compound, and the storage modulus of a cured product obtained by homopolymerizing the 2-cyanoacrylate compound is 1.0 × 10⁻⁶ at 25°C. 7 A 2-cyanoacrylate adhesive composition with a Pa of 0.5 or less is disclosed.

[0004] Furthermore, Patent Document 1 states that the storage modulus of a hardened product obtained by homopolymerization is 1.0 × 10 at 25°C. 5 Pa or more 1.0×10 7 A cured product containing a 2-cyanoacrylate compound (excluding diethylene glycol monoethyl ether cyanoacrylate) with a Pa or less, or obtained by homopolymerization, has a storage modulus of 1.0 × 10⁻¹⁶ at 25°C. 7 Larger than Pa, 5.0 × 10 7 A curable composition for flexible articles is disclosed, which contains a 2-cyanoacrylate compound with a Pa of less than or equal to Pa and a polyfunctional cyanoacrylate compound. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2023 / 286710 [Patent Document 2] Japanese Patent Application Laid-Open No. 2024-83141

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, although the conventionally known 2-cyanoacrylate-based adhesive composition has flexibility of the cured product after curing, its shear adhesive strength is low. Therefore, the conventional 2-cyanoacrylate-based adhesive composition cannot enhance both the shear adhesive strength and the flexibility of the cured product, and there is room for improvement.

[0007] The present invention has been made in view of such problems, and aims to provide a 2-cyanoacrylate-based adhesive composition capable of achieving both high shear adhesive strength and flexibility of the cured product.

Means for Solving the Problems

[0008] The 2-cyanoacrylate-based adhesive composition according to the present invention is as follows.

[0009] [1] A 2-cyanoacrylate-based compound (A) represented by the following general formula (1), and a 2-cyanoacrylate-based compound (B) represented by the following general formula (2), are contained in a 2-cyanoacrylate-based adhesive composition. However, in the general formula (1), each L independently represents -CH2CH2-, -CH2CH2CH2-, -CH(R 1 )CH2- or -CH2CH(R 1 )-, R 1 represents a linear or branched alkyl group having 1 or more and 6 or less carbon atoms which may have a substituent, and R 2 represents a linear or branched alkyl group having 1 or more and 8 or less carbon atoms which may have a substituent. However, in the general formula (2), R 3 is an alkyl group, an alkenyl group or an alkoxyalkyl group having 1 or more and 10 or less carbon atoms.

[0010] [ka]

[0011] [ka]

[0012] [2] The storage modulus at 25°C of the cured product obtained by curing the 2-cyanoacrylate adhesive composition is 5.0 × 10⁻⁶. 6 Pa or more 3.2×10 8 It is less than or equal to Pa. [1] The 2-cyanoacrylate adhesive composition described above. [3] The maximum value of the loss loss tangent of the cured product obtained by curing the 2-cyanoacrylate adhesive composition is tanδ. max The temperature indicating this is 90°C or lower. A 2-cyanoacrylate adhesive composition as described in [1] or [2]. [4] The shear adhesive strength to the aluminum substrate, measured in accordance with JIS K 6861-1995, was 5.0 N / mm². 2 That's all. A 2-cyanoacrylate adhesive composition as described in any one of [1] to [3]. [5] The elongation rate in the stress-strain curve of the cured product obtained by curing the 2-cyanoacrylate adhesive composition is 100% or more. A 2-cyanoacrylate adhesive composition as described in any one of [1] to [4]. [6] The fracture stress in the stress-strain curve of the cured product obtained by curing the 2-cyanoacrylate adhesive composition is greater than 0.5 MPa and less than or equal to 20 MPa. A 2-cyanoacrylate adhesive composition as described in any one of [1] to [5]. [7] The 2-cyanoacrylate compound (B) comprises at least one compound selected from the group consisting of methyl-2-cyanoacrylate, ethyl-2-cyanoacrylate, propyl-2-cyanoacrylate, isopropyl-2-cyanoacrylate, butyl-2-cyanoacrylate, and isobutyl-2-cyanoacrylate. The content of the 2-cyanoacrylate compound (B) is 1% by mass or more and 30% by mass or less, relative to 100% by mass of the total amount of cyanoacrylate compounds contained in the composition. A 2-cyanoacrylate adhesive composition as described in any one of [1] to [6]. [8] The 2-cyanoacrylate compound (B) comprises at least one compound selected from the group consisting of methoxyethyl-2-cyanoacrylate, ethoxyethyl-2-cyanoacrylate, and methoxypropyl-2-cyanoacrylate. The content of the 2-cyanoacrylate compound (B) is 1% by mass or more and 90% by mass or less, relative to 100% by mass of the total amount of cyanoacrylate compounds contained in the composition. A 2-cyanoacrylate adhesive composition as described in any one of [1] to [7]. [Effects of the Invention]

[0013] The above-mentioned 2-cyanoacrylate adhesive composition has the above-mentioned structure. Therefore, the above-mentioned 2-cyanoacrylate adhesive composition can increase both shear adhesive strength and the flexibility of the cured product, and can achieve a balance between shear adhesive strength and the flexibility of the cured product. [Modes for carrying out the invention]

[0014] One embodiment of the present invention will be described below, but the present invention is not limited to the examples given in the following embodiments. Furthermore, the lower and upper limits of the numerical ranges shown below can be arbitrarily combined, including the values ​​described in the examples (details omitted below).

[0015] The 2-cyanoacrylate adhesive composition of this embodiment (hereinafter sometimes referred to as "this adhesive composition") contains a 2-cyanoacrylate compound (A) and a 2-cyanoacrylate compound (B). This adhesive composition will now be described in detail.

[0016] 1. Cyanoacrylate compounds 1.1 2-Cyanoacrylate compounds (A) This adhesive composition contains a cyanoacrylate compound (A) represented by the following general formula (1). This adhesive composition may contain only one type of 2-cyanoacrylate compound (A), or it may contain two or more types.

[0017] [ka]

[0018] In general formula (1), L is independently -CH2CH2-, -CH2CH2CH2-, and -CH(R 1 )CH2- or -CH2CH(R 1 )- represents -CH2CH2-, -CH(R 1 )CH2- or -CH2CH(R 1 It is preferable to represent -CH(R 1 )CH2- or -CH2CH(R 1 It is preferable to represent it as )-.

[0019] In general formula (1), R 1 R represents a linear or branched alkyl group having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms, which may have substituents. Examples of the substituents include aryl groups, halogen atoms, alkoxy groups, allyloxy groups, cyano groups, alkoxycarbonyl groups, allyloxycarbonyl groups, acyl groups, and acyloxy groups. 1Specifically, examples include methyl groups, ethyl groups, propyl groups, and butyl groups. From the viewpoint of ensuring a balance between shear adhesion strength and the flexibility of the cured product, methyl groups or ethyl groups are preferred, and methyl groups are more preferred.

[0020] In general formula (1), R 2 R represents a linear or branched alkyl group having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, and more preferably 1 to 3 carbon atoms, which may have substituents. 1 Examples of substituents mentioned above include R. 2 Specifically, the group is preferably a methyl group, an ethyl group, an n-propyl group, or an isopropyl group, more preferably a methyl or an ethyl group, and even more preferably a methyl group.

[0021] Specific examples of 2-cyanoacrylate compounds (A) represented by general formula (1) include 2-(2-methoxyethoxy)ethyl, 2-(2-methoxypropoxy)propyl, 2-(2-ethoxyethoxy)ethyl, 2-(2-propoxyethoxy)ethyl, 2-[2-(1-methylethoxy)ethoxy]ethyl, 2-[2-(2-methylpropoxy)ethoxy]ethyl, 2-[2-(1-methylpropoxy)ethoxy]ethyl, 2-[2-(1-ethylpropoxy)ethoxy]ethyl, 2-(2-methoxy-1-methylethoxy)ethyl, 2-(2-methyl Toxy-2-methylethoxy)ethyl, 2-(2-ethoxy-1-methylethoxy)ethyl, 2-(2-ethoxy-2-methylethoxy)ethyl, 1-(2-methoxyethoxy)propyl-2-yl, 2-(2-methoxyethoxy)propyl-1-yl, 1-(2-ethoxyethoxy)propyl-2-yl, 2-(2-ethoxyethoxy)propyl-1-yl, 1-(2-methoxy-1-methylethoxy)propyl-2-yl, 1-(2-methoxy-2-methylethoxy)propyl-2-yl, 2-(2-methoxy-1-methylethoxy)propyl-1 -yl, 2-(2-methoxy-2-methylethoxy)propyl-1-yl, 1-(2-ethoxy-1-methylethoxy)propyl-2-yl, 1-(2-ethoxy-2-methylethoxy)propyl-2-yl, 2-(2-ethoxy-1-methylethoxy)propyl-1-yl, 2-(2-ethoxy-2-methylethoxy)propyl-1-yl, 1-(2-propoxy-1-methylethoxy)propyl-2-yl, 1-(2-propoxy-2-methylethoxy)propyl-2-yl, 2-(2-propoxy-1-methylethoxy)propyl-1-yl, 2 -(2-propoxy-2-methylethoxy)propyl-1-yl, 1-(2-butoxy-1-methylethoxy)propyl-2-yl, 1-(2-butoxy-2-methylethoxy)propyl-2-yl, 2-(2-butoxy-1-methylethoxy)propyl-1-yl, 2-(2-butoxy-2-methylethoxy)propyl-1-yl, 1-(2-hexyloxy-1-methylethoxy)propyl-2-yl, 1-(2-hexyloxy-2-methylethoxy)propyl-2-yl, 2-(2-hexyloxy-1-methylethoxy)propyl-1-yl,Examples include 2-cyanoacrylate esters such as 2-(2-hexyloxy-2-methylethoxy)propyl-1-yl.

[0022] Among the above, from the viewpoint of ensuring a balance between shear adhesive strength and the flexibility of the cured product, 2-(2-methoxypropoxy)propyl, 2-(2-methoxyethoxy)ethyl 1-(2-methoxy-1-methylethoxy)propyl-2-yl, 1-(2-methoxy-2-methylethoxy)propyl-2-yl, 2-(2-methoxy-1-methylethoxy)propyl-1-yl, or 2-(2-methoxy-2-methylethoxy)propyl-1-yl 2-cyanoacrylate 2-(2-methoxypropoxy)propyl, 1-(2-methoxy-1-methylethoxy)propyl-2-yl, 1-(2-methoxy-2-methylethoxy)propyl-2-yl, 2-(2-methoxy-1-methylethoxy)propyl-1-yl, or 2-(2-methoxy-2-methylethoxy)propyl-1-yl 2-cyanoacrylate esters are preferred, and 2-(2-methoxypropoxy)propyl 2-cyanoacrylate esters are even more preferred.

[0023] The content of 2-cyanoacrylate compound (A) is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on 100% by mass of the total amount of cyanoacrylate compounds contained in the composition, from the viewpoint of ensuring a balance between shear adhesive strength and the flexibility of the cured product. The upper limit of the content of 2-cyanoacrylate compound (A) is not particularly limited, but for example, it can be 99% by mass or less, based on 100% by mass of the total amount of cyanoacrylate compounds contained in the composition.

[0024] Furthermore, if 2-cyanoacrylate compound (B) contains at least one compound selected from the group consisting of methyl-2-cyanoacrylate, ethyl-2-cyanoacrylate, propyl-2-cyanoacrylate, isopropyl-2-cyanoacrylate, butyl-2-cyanoacrylate, and isobutyl-2-cyanoacrylate (see details below), the content of 2-cyanoacrylate compound (A) is preferably 50% to 99% by mass, more preferably 70% to 99% by mass, and even more preferably 80% to 99% by mass, based on 100% by mass of the total amount of cyanoacrylate compounds contained in the composition.

[0025] The total amount of cyanoacrylate compounds refers to the sum of the amounts of 2-cyanoacrylate compound (A), 2-cyanoacrylate compound (B), and other cyanoacrylate compounds that may be included in this adhesive composition.

[0026] Furthermore, if 2-cyanoacrylate compound (B) contains at least one compound selected from the group consisting of methoxyethyl-2-cyanoacrylate, ethoxyethyl-2-cyanoacrylate, and methoxypropyl-2-cyanoacrylate (see details below), the content of 2-cyanoacrylate compound (A) is preferably 10% to 99% by mass, more preferably 10% to 95% by mass, and even more preferably 20% to 95% by mass, based on 100% by mass of the total amount of cyanoacrylate compounds contained in the composition.

[0027] 1.2 2-Cyanoacrylate compounds (B) This adhesive composition contains a cyanoacrylate compound (B) represented by the following general formula (2). This adhesive composition may contain only one type of 2-cyanoacrylate compound (B), or it may contain two or more types.

[0028] [ka]

[0029] In general formula (2), R 3 This is an alkyl group, alkenyl group, or alkoxyalkyl group having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms.

[0030] Specific examples of 2-cyanoacrylate esters represented by general formula (2) include, for example, methyl-2-cyanoacrylate, ethyl-2-cyanoacrylate, propyl-2-cyanoacrylate, isopropyl-2-cyanoacrylate, butyl-2-cyanoacrylate, isobutyl-2-cyanoacrylate, sec-butyl-2-cyanoacrylate, tert-butyl-2-cyanoacrylate, pentyl-2-cyanoacrylate, hexyl-2-cyanoacrylate, cyclohexyl-2-cyanoacrylate, octyl-2-cyanoacrylate, 2-ethylhexyl-2-cyanoacrylate, allyl-2-cyanoacrylate, benzyl-2-cyanoacrylate, methoxyethyl-2-cyanoacrylate, ethoxyethyl-2-cyanoacrylate, methoxypropyl-2-cyanoacrylate, and tetrahydrofurfuryl-2-cyanoacrylate. These may be used individually or in combination of two or more types.

[0031] The 2-cyanoacrylate compound (B) may include at least one compound selected from the group consisting of methyl-2-cyanoacrylate, ethyl-2-cyanoacrylate, propyl-2-cyanoacrylate, isopropyl-2-cyanoacrylate, butyl-2-cyanoacrylate, and isobutyl-2-cyanoacrylate, from the viewpoint of ensuring both shear adhesion strength and flexibility of the cured product. In this case, it is more preferable that the 2-cyanoacrylate compound (B) includes at least one compound selected from the group consisting of methyl-2-cyanoacrylate and ethyl-2-cyanoacrylate, from the viewpoint of ensuring improved shear adhesion strength.

[0032] Furthermore, in the above case, the content of 2-cyanoacrylate compound (B) is preferably 1% by mass or more and 50% by mass or less, more preferably 1% by mass or more and 30% by mass or less, and even more preferably 1% by mass or more and 20% by mass or less, based on 100% by mass of the total amount of cyanoacrylate compounds contained in the composition, from the viewpoint of ensuring both shear adhesive strength and flexibility of the cured product.

[0033] The 2-cyanoacrylate compound (B) may also include at least one compound selected from the group consisting of methoxyethyl-2-cyanoacrylate, ethoxyethyl-2-cyanoacrylate, and methoxypropyl-2-cyanoacrylate, from the viewpoint of ensuring a balance between shear adhesion strength and the flexibility of the cured product. In this case, it is more preferable that the 2-cyanoacrylate compound (B) includes at least one compound selected from the group consisting of methoxyethyl-2-cyanoacrylate and ethoxyethyl-2-cyanoacrylate, from the viewpoint of ensuring an improvement in shear adhesion strength.

[0034] Furthermore, in the above case, the content of 2-cyanoacrylate compound (B) is preferably 1% by mass or more and 90% by mass or less, more preferably 5% by mass or more and 80% by mass or less, based on 100% by mass of the total amount of cyanoacrylate compounds contained in the composition, from the viewpoint of ensuring both shear adhesive strength and flexibility of the cured product.

[0035] 1.3 Other ingredients This adhesive composition may contain other components besides 2-cyanoacrylate compound (A) and 2-cyanoacrylate compound (B), to the extent that it does not significantly impair its properties. Other components include 2-cyanoacrylate compounds other than 2-cyanoacrylate compound (A) and 2-cyanoacrylate compound (B), stabilizers, curing accelerators, plasticizers, thickeners, particles, colorants, fragrances, solvents, and strength enhancers.

[0036] Other 2-cyanoacrylate compounds besides 2-cyanoacrylate compounds (A) and 2-cyanoacrylate compound (B) include phenyl, n-dodecyl, 2,2,2-trifluoroethyl, hexafluoroisopropyl, chloroethyl, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, triethylene glycol monohexyl ether, triethylene glycol mono-2-ethylhexyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monobutyl ether, tripropylene glycol monopentyl ether, tripropylene glycol monohexyl ether, and tetrapropylene glycol monomethyl ether. Examples include 2-cyanoacrylate esters such as ethyl ether, tetrapropylene glycol monoethyl ether, tetrapropylene glycol monopropyl ether, tetrapropylene glycol monobutyl ether, and tetrapropylene glycol monohexyl ether; polyoxyalkylene polyols, polyester polyols, polycarbonate polyols, polyurethane polyols, polyamide polyols, polyester polyamide polyols, acrylic polyols, polybutadiene polyols, hydrogenated polybutadiene polyols, ethylene-butylene copolymer polyols, polyisoprene polyols, hydrogenated polyisoprene polyols, polyvinyl butyral, polyvinyl formal, polyvinyl alcohol, phenolic resins, silane compounds having hydroxyl groups at both ends, and siloxane compounds having hydroxyl groups at both ends. These 2-cyanoacrylate compounds may be used individually or in combination of two or more.

[0037] Examples of stabilizers include (1) aliphatic sulfonic acids such as sulfur dioxide and methanesulfonic acid, aromatic sulfonic acids such as p-toluenesulfonic acid, boron trifluoride complexes such as boron trifluoride methanol and boron trifluoride diethyl ether, anionic polymerization inhibitors such as HBF4 and trialkylborate, and (2) radical polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, t-butylcatechol, catechol, and pyrogallol. These may be used individually or in combination of two or more.

[0038] Any curing accelerator that promotes the anionic polymerization of the adhesive composition can be used. Examples of curing accelerators include polyether compounds, calixalenes, thiacalixalenes, pyrogallolalenes, and onium salts. These may be used individually or in combination of two or more.

[0039] Examples of plasticizers include triethyl acetyl citrate, tributyl acetyl citrate, dimethyl adipate, diethyl adipate, dimethyl sebacate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisodecyl phthalate, dihexyl phthalate, diheptyl phthalate, dioctyl phthalate, bis(2-ethylhexyl) phthalate, diisononyl phthalate, diisotridecyl phthalate, dipentadecyl phthalate, dioctyl terephthalate, diisononyl isophthalate, decyl toluate, bis(2-ethylhexyl) camphorate, 2-ethylhexylcyclohexyl carboxylate, diisobutyl fumarate, diisobutyl maleate, triglyceride caproate, 2-ethylhexyl benzoate, and dipropylene glycol dibenzoate. Among these, tributyl acetyl citrate, dimethyl adipate, dimethyl phthalate, 2-ethylhexyl benzoate, or dipropylene glycol dibenzoate are preferred from the viewpoint of good compatibility with 2-cyanoacrylate compounds and high plasticization efficiency. These may be used individually or in combination of two or more.

[0040] Examples of thickening agents include polymethyl methacrylate, copolymers of methyl methacrylate and acrylic acid esters, copolymers of methyl methacrylate and other methacrylic acid esters, acrylic rubber, polyvinyl acetate, polyvinyl chloride, polyurethane resin, polyamide resin, polystyrene, cellulose ester, polyalkyl-2-cyanoacrylate, and ethylene-vinyl acetate copolymer. These may be used individually or in combination of two or more.

[0041] Examples of particles include thermoplastic resins such as polyethylene, polypropylene, polymethylpentene, acrylic resin, polyvinyl chloride, polytetrafluoroethylene, polyethylene terephthalate, polybutylene terephthalate, polysulfone, and polyphenylene oxide; crosslinked resins such as unsaturated polyester, divinylbenzene polymer, divinylbenzene-styrene copolymer, divinylbenzene-(meth)acrylic acid ester copolymer, and diallyl phthalate polymer; inorganic compounds such as spherical silica, glass beads, and glass fibers; silicone compounds; and organic-inorganic composite particles comprising an organic polymer skeleton and a polysiloxane skeleton. These may be used individually or in combination of two or more.

[0042] While there are no particular restrictions on the content of other components, the content of 2-cyanoacrylate compounds other than 2-cyanoacrylate compound (A) and 2-cyanoacrylate compound (B) is preferably 50% by mass or less, and more preferably 20% by mass or less, relative to 100% by mass of the total amount of cyanoacrylate compounds contained in the composition. Furthermore, the content of other components other than the above-mentioned 2-cyanoacrylate compounds is preferably 20% by mass or less, and more preferably 10% by mass or less, relative to the total mass of the adhesive composition.

[0043] 2. Storage modulus of the cured product at 25°C The storage modulus (G') of the cured product of this adhesive composition at 25°C is 5.0 × 10⁻⁶. 6Pa or more 3.2×10 8 It is preferable that the pressure be Pa or less. This configuration ensures that the flexibility of the cured product is maintained.

[0044] The above storage modulus is set to 7.5 × 10⁻⁶ from the viewpoint of improving the holding power of the adhesive composition. 6 It is more preferable that it be Pa or higher, 1.0 × 10 7 It is even more preferable that the storage modulus be Pa or higher. 8 It is more preferably Pa or less, 1.1 × 10 8 It is even more preferable that it be less than or equal to Pa, 1.0 × 10 8 It is particularly preferable that the value be Pa or less.

[0045] The above storage modulus can be measured as follows. The adhesive composition is injected between the fixtures of a dynamic viscoelasticity measuring device coated with triethanolamine. The storage modulus is then measured using the dynamic viscoelasticity measuring device under the conditions of a frequency of 1 Hz, a temperature of 25°C, and a thickness of 300 μm. Confirmation that the storage modulus of the adhesive composition has stopped changing is made, and this is considered the cured product. Next, using the cured product, the storage modulus of the cured product due to shear is measured in the range of -30°C to 150°C under the conditions of a frequency of 1 Hz, a heating rate of 2°C / min, and a relative humidity of 50%, to determine the storage modulus of the cured product at 25°C. This is considered the storage modulus of the cured product at 25°C. Anton Paar's "MCR301" or a similar device can be used as the dynamic viscoelasticity measuring device.

[0046] 3. Maximum value of the loss tangent of the hardened material: tanδ max Temperatures that indicate This adhesive composition has a maximum value of tanδ, which is the loss tangent of the cured product obtained by curing this adhesive composition. max It is preferable that the temperature at which this occurs (hereinafter sometimes referred to as the loss tangent maximum temperature) is 90°C or lower. This configuration makes it possible to more reliably ensure the flexibility of the cured product.

[0047] The above loss tangent maximum temperature is more preferably 80°C or lower, even more preferably 70°C or lower, and particularly preferably 60°C or lower, from the viewpoint of the flexibility of the cured product. Furthermore, the above loss tangent maximum temperature can be 20°C or higher, from the viewpoint of improving the holding power of the adhesive composition.

[0048] The above loss tangent maximum temperature can be measured as follows. The adhesive composition is injected between the fixtures of a dynamic viscoelasticity measuring device coated with triethanolamine, and the storage modulus is measured using the dynamic viscoelasticity measuring device under the conditions of frequency 1 Hz, temperature 25°C, and thickness 300 μm. After confirming that the change in the storage modulus of the adhesive composition has stopped, this is considered the cured product obtained by curing the adhesive composition. Next, using the above cured product, the dynamic viscoelastic spectrum is obtained in the range of -30°C to 150°C under the conditions of frequency 1 Hz, heating rate 2°C / min, and relative humidity 50%, and the maximum value of the loss tangent (tanδ) is determined (tanδ). max The temperature at which this occurs is measured. This is the maximum value of the loss tangent tangent tanδ of the cured product formed by the curing of the adhesive composition. max The temperature at which this occurs (loss tangent maximum temperature) is defined as the temperature at which this occurs. If two or more peaks are observed in the dynamic viscoelastic spectrum, the loss tangent (tanδ) of the largest peak is defined as the maximum value (tanδ). max ) Furthermore, as the dynamic viscoelasticity measuring device, an Anton Paar "MCR301" or a device of comparable quality can be used.

[0049] 4. Shear bond strength This adhesive composition has a shear adhesive strength of 5.0 N / mm² to an aluminum substrate, as measured in accordance with JIS K 6861-1995. 2 The above configuration is preferable. This configuration ensures that shear adhesive strength is secured.

[0050] The above shear bond strength is set to 5.5 N / mm² from the perspective of ensuring sufficient bond strength. 2It is more preferable that the value be greater than or equal to 6.0 N / mm 2 It is even more preferable that the above is true. The upper limit of the above shear bonding strength is not particularly limited; for example, 15.0 N / mm². 2 The following is also acceptable.

[0051] The above shear bond strength can be measured as follows. A 2.0 mm thick aluminum plate (material specified in JIS A6061P) was used as a test specimen, bonded with this adhesive composition, and cured for one day at a temperature of 23°C and a relative humidity of 60% RH. Then, using a tensile testing machine, the tensile shear bond strength (N / mm²) was measured in accordance with JIS K 6861-1999 at a temperature of 23°C and a relative humidity of 60% at a tensile speed of 10.0 mm / min. 2 The following is measured: This will be taken as the shear adhesion strength to the aluminum substrate. A Shimadzu Corporation "Autograph AGX-V2" or a similar device can be used as the tensile testing machine.

[0052] 5. Elongation of the cured product Preferably, the elongation rate in the stress-strain curve of the cured product obtained by curing this adhesive composition is 100% or more. This configuration makes it possible to more reliably ensure the flexibility of the cured product.

[0053] The above elongation rate is more preferably 150% or more, and even more preferably 300% or more, from the viewpoint of the flexibility of the cured product. However, there is no particular upper limit to the above elongation rate, and it may be, for example, 2000% or less.

[0054] The above growth rate can be measured as follows. Add 1 μL of triethanolamine to 1 g of this adhesive composition and stir. Place this mixture on a release PET film and pour it into a 1 mm thick silicone rubber mold. Then, cover it with another release film, sandwich it between glass plates, and leave it undisturbed at 23°C for 24 hours to allow it to fully cure. After curing, remove the mold and release film to prepare a cured product with a width of 5 mm, a length of 50 mm, and a thickness of 1 mm. Next, measure the stress-strain curve of this cured product using a tensile testing machine and calculate the elongation at fracture. As the release PET film, you can use "Purex A31" manufactured by Toyobo Film Solutions Co., Ltd. or a similar product. As the tensile testing machine, you can use "Autograph AGX-V2" manufactured by Shimadzu Corporation or a similar device.

[0055] 6. Fracture stress of the cured material In this adhesive composition, it is preferable that the fracture stress in the stress-strain curve of the cured product obtained by curing the adhesive composition is greater than 0.5 MPa and less than or equal to 20 MPa. This configuration makes it possible to more reliably ensure the flexibility of the cured product.

[0056] The fracture stress is more preferably 1.0 MPa or higher, and even more preferably 1.5 MPa or higher, from the viewpoint of improving the holding power of the adhesive composition. The fracture stress is more preferably 15 MPa or lower, and even more preferably 10 MPa or lower, from the viewpoint of the flexibility of the cured product.

[0057] The above fracture stress can be measured as follows. Add 1 μL of triethanolamine to 1 g of this adhesive composition and stir. Place this mixture on a release PET film and pour it into a 1 mm thick silicone rubber mold. Then, cover it with another release film, sandwich it between glass plates, and leave it undisturbed at 23°C for 24 hours to allow it to fully cure. After curing, remove the mold and release film to prepare a cured product with a width of 5 mm, a length of 50 mm, and a thickness of 1 mm. Next, measure the stress-strain curve of this cured product using a tensile testing machine and calculate the fracture stress. As the release PET film, you can use "Purex A31" manufactured by Toyobo Film Solutions Co., Ltd. or a similar product. As the tensile testing machine, you can use "Autograph AGX-V2" manufactured by Shimadzu Corporation or a similar device.

[0058] 7.Applications This adhesive composition can be suitably used, for example, as a so-called instant adhesive. Because this adhesive composition achieves both shear bonding strength and flexibility of the cured product, and ensures flexibility of the cured product, it can be used in a wide range of fields, including industrial, medical, and household applications.

[0059] Furthermore, this adhesive composition can be suitably used on various substrates made of metal, resin, rubber, wood, ceramics, etc., is more suitably used on metals, and is particularly suitably used on aluminum substrates. [Examples]

[0060] The present invention will be described more specifically based on examples, but the present invention is not limited thereto. In the following, parts and % are based on mass unless otherwise specified.

[0061] <Preparation of 2-cyanoacrylate adhesive compositions> (Sample 1) A 2-cyanoacrylate adhesive composition of Sample 1 was prepared by adding 90 parts by mass of 2-(2-methoxypropoxy)propyl-2-cyanoacrylate as 2-cyanoacrylate compound (A) and 10 parts by mass of ethoxyethyl-2-cyanoacrylate as 2-cyanoacrylate compound (B), and stirring at 23°C for 1 hour. The chemical formula of 2-(2-methoxypropoxy)propyl-2-cyanoacrylate is shown below.

[0062] [ka]

[0063] (Samples 2-12, Sample 1C-3C) Samples 2 to 12 and 1C to 3C were prepared in the same manner as Sample 1, except that the composition of the 2-cyanoacrylate adhesive composition was changed as shown in Table 1.

[0064] <Various measurements> For each 2-cyanoacrylate adhesive composition prepared, the shear adhesive strength to the aluminum substrate, the storage modulus of the cured product at 25°C, and the maximum value of the loss tangent of the cured product (tanδ) were measured according to the measurement method described above. max The temperature at which the loss tangent of the cured material is maximized (the temperature at which the loss tangent of the cured material is maximized), the elongation of the cured material, and the fracture stress of the cured material were measured.

[0065] <Various evaluations> Based on the measurement results, the following (1) to (3) were evaluated. (1) Evaluation of shear bond strength Based on the measurement results of shear bond strength, the adhesive strength of the adhesive composition was evaluated according to the following criteria. The evaluation results are shown in Table 1. A: 6.0 N / mm 2 (The adhesive strength is sufficiently high.) B: 5.0 N / mm 2 More than 6.0N / mm 2 Less than (high adhesive strength) C: 5.0 N / mm 2 Less than (low adhesive strength) (2) Evaluation of the flexibility of the cured product Based on the measurement results of the elongation rate of the cured material, the flexibility of the cured material was evaluated according to the following criteria. The evaluation results are shown in Table 1. A: 300% or more (the cured product has very high flexibility) B: 100% or more but less than 300% (high flexibility of the cured product) C: Less than 100% (Poor flexibility of the cured product) (3) Overall evaluation Based on the evaluation results in (1) and (2) above, the balance between shear bonding strength and the flexibility of the cured product was evaluated according to the following criteria. The evaluation results are shown in Table 1. A+: Excellent balance between shear bonding strength and cured product flexibility. A: The balance between shear bonding strength and the flexibility of the cured product is good. B: Poor balance between shear bonding strength and cured product flexibility.

[0066] Table 1 summarizes the detailed composition, various measurement results, and evaluation results for each 2-cyanoacrylate adhesive composition.

[0067] [Table 1]

[0068] Table 1 shows the following: Samples 1C and 3C contain 2-cyanoacrylate compound (B) as cyanoacrylate compounds, but do not contain 2-cyanoacrylate compound (A). Therefore, while samples 1C and 3C were able to increase their shear adhesion strength, their elongation was low, and they could not achieve a balance with the flexibility of the cured product. Furthermore, the inferior flexibility of the cured product is related to the flexibility of the cured product, specifically the maximum value of the loss tangent of the cured product, tanδ, compared to the other samples. max This was further supported by the fact that the temperature at which the curing occurred was excessively high, the elongation of the cured material was excessively low, and the fracture stress of the cured material was excessively high.

[0069] Sample 2C contains 2-cyanoacrylate compound (A) but not 2-cyanoacrylate compound (B). Therefore, although the cured product of sample 2C was flexible, its shear adhesive strength was low, and it was not possible to achieve both flexibility and shear adhesive strength.

[0070] In contrast, samples 1 to 12 were able to achieve a balance between shear bonding strength and the flexibility of the cured product.

[0071] The present invention is not limited to the embodiments and examples described above, and various modifications are possible without departing from the spirit of the invention. Furthermore, each of the configurations shown in the embodiments and examples can be combined in any way.

Claims

1. A 2-cyanoacrylate compound (A) represented by the following general formula (1), A compound (B) of the 2-cyanoacrylate type represented by the following general formula (2) contains A 2-cyanoacrylate adhesive composition. 【Chemistry 1】 (However, in General Formula (1), each L is independently -CH ２ CH ２ -, -CH ２ CH ２ CH ２ -, -CH(R １ )CH ２ - or -CH ２ CH(R １ )-, R １ represents a linear or branched alkyl group having 1 to 6 carbon atoms which may have a substituent, and R ２ represents a linear or branched alkyl group having 1 to 8 carbon atoms which may have a substituent.) 【Chemistry 2】 (However, in general formula (2), R ３ (This is an alkyl group, alkenyl group, or alkoxyalkyl group having 1 to 10 carbon atoms.)

2. The storage modulus at 25°C of the cured product obtained by curing the 2-cyanoacrylate adhesive composition is 5.0 × 10⁻⁶. ６ Pa or more 3.2×10 ８ It is less than or equal to Pa. The 2-cyanoacrylate adhesive composition according to claim 1.

3. The maximum value of the loss tangent of the cured product obtained by curing the 2-cyanoacrylate adhesive composition is tanδ. ｍａｘ The temperature that indicates this is 90°C or lower. The 2-cyanoacrylate adhesive composition according to claim 1.

4. The shear adhesive strength to the aluminum substrate, measured in accordance with JIS K 6861-1995, was 5.0 N / mm². ２ That's all. The 2-cyanoacrylate adhesive composition according to claim 1.

5. The elongation rate in the stress-strain curve of the cured product obtained by curing the 2-cyanoacrylate adhesive composition is 100% or more. The 2-cyanoacrylate adhesive composition according to claim 1.

6. The fracture stress in the stress-strain curve of the cured product obtained by curing the 2-cyanoacrylate adhesive composition is greater than 0.5 MPa and less than or equal to 20 MPa. The 2-cyanoacrylate adhesive composition according to claim 1.

7. The 2-cyanoacrylate compound (B) comprises at least one compound selected from the group consisting of methyl-2-cyanoacrylate, ethyl-2-cyanoacrylate, propyl-2-cyanoacrylate, isopropyl-2-cyanoacrylate, butyl-2-cyanoacrylate, and isobutyl-2-cyanoacrylate. The content of the 2-cyanoacrylate compound (B) is 1% by mass or more and 30% by mass or less, relative to 100% by mass of the total amount of cyanoacrylate compounds contained in the composition. The 2-cyanoacrylate adhesive composition according to claim 1.

8. The 2-cyanoacrylate compound (B) comprises at least one compound selected from the group consisting of methoxyethyl-2-cyanoacrylate, ethoxyethyl-2-cyanoacrylate, and methoxypropyl-2-cyanoacrylate. The content of the 2-cyanoacrylate compound (B) is 1% by mass or more and 90% by mass or less, relative to 100% by mass of the total amount of cyanoacrylate compounds contained in the composition. The 2-cyanoacrylate adhesive composition according to claim 1.

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