2-cyanoacrylate adhesive composition

Abstract

A 2-cyanoacrylate adhesive composition comprising a 2-cyanoacrylate compound and a polyfunctional cyanoacrylate compound, wherein the storage modulus at 25°C of a cured product obtained by homopolymerization of the 2-cyanoacrylate compound is no higher than 1.0×107 Pa.

Description

[Technical Field]

[0001] The present disclosure relates to 2-cyanoacrylate adhesive compositions. [Background technology]

[0002] Adhesive compositions containing 2-cyanoacrylate compounds have the unique anionic polymerization property of 2-cyanoacrylate compounds, which initiate polymerization with weak anions, such as traces of moisture, adhering to the surface of the adherend, enabling them to firmly bond various materials in a short period of time. For this reason, they are used as so-called instant adhesives in a wide range of fields, including industrial, medical, and household applications.

[0003] For example, Japanese Patent No. 5267571 proposes an adhesive composition containing a 2-cyanoacrylic acid ester and a polyfunctional cyanoacrylic acid ester having two or more 2-cyanoacryloyl groups, in which the number average molecular weight of the (b) polyfunctional cyanoacrylic acid ester is 1,000 to 50,000, and the amount of the (b) polyfunctional cyanoacrylic acid ester is 1 part by mass to 400 parts by mass per 100 parts by mass of the 2-cyanoacrylic acid ester. Summary of the Invention [Problem to be solved by the invention]

[0004] Adhesive compositions containing 2-cyanoacrylate compounds have the problem that the cured product is hard and brittle and has no crosslinked structure, so while they have excellent shear bond strength, they have low peel bond strength. In recent years, adhesive compositions are required to have excellent peel bond strength when cured against various materials, for example, excellent peel bond strength against rubbers such as ethylene propylene diene rubber (EPDM).

[0005] The present inventors have found that the adhesive composition disclosed in Japanese Patent No. 5267571 leaves room for improvement in terms of peel adhesive strength of the cured product to rubber.

[0006] The present inventors have found that a cured product containing a 2-cyanoacrylate compound and a polyfunctional cyanoacrylate compound, obtained by homopolymerizing the 2-cyanoacrylate compound, has a storage modulus of 1.0 × 10 at 25°C. 7 It has been found that a 2-cyanoacrylate adhesive composition having a viscosity of 100 Pa or less has improved peel adhesion strength to rubber of the cured product, and also has a superior rate of increase in peel adhesion strength, compared to an adhesive composition that does not contain the above-mentioned polyfunctional cyanoacrylate compound.

[0007] Therefore, an object of the present disclosure is to provide a 2-cyanoacrylate adhesive composition that exhibits an excellent increase in peel strength of the cured product against rubbers such as EPDM. [Means for solving the problem]

[0008] The specific means for achieving the objectives are as follows: <1> A cured product obtained by homopolymerizing a 2-cyanoacrylate compound and a polyfunctional cyanoacrylate compound has a storage modulus of 1.0 × 10 at 25°C. 7 2-cyanoacrylate adhesive composition having a viscosity of 100 Pa or less. <2> A cured product of the 2-cyanoacrylate adhesive composition having a width of 5 mm, a length of 50 mm and a thickness of 1 mm is fixed to a tensile tester with a jig distance of 20 mm (L0), a mark is made at the jig fixing position, and the product is pulled at a pulling rate of 20 mm / min until the jig distance reaches 40 mm (L1), after which the jig is released from the tester and the length (L2) between the marks is measured after 1 minute has passed. The elongation recovery rate (%) calculated using the following formula is 70% or more. <1> 2. The 2-cyanoacrylate adhesive composition according to claim 1. Elongation recovery rate (%): {(L1-L2) / (L1-L0)}×100 <3> A cured product of the 2-cyanoacrylate adhesive composition having a width of 5 mm, a length of 50 mm and a thickness of 1 mm is fixed to a tensile tester with a jig distance of 20 mm (L0), a mark is made at the jig fixing position, and the product is pulled at a pulling rate of 20 mm / min until the jig distance reaches 40 mm (L1), after which the jig is released from the tester and the length (L3) between the marks is measured after 5 minutes have passed. The elongation recovery rate (%) calculated using the following formula is 80% or more. <1> or <2> 2. The 2-cyanoacrylate adhesive composition according to claim 1. Elongation recovery rate (%): {(L1-L3) / (L1-L0)}×100 <4> A cured product of the 2-cyanoacrylate adhesive composition having a width of 5 mm, a length of 50 mm and a thickness of 1 mm is fixed to a tensile tester with a jig distance of 20 mm (L0), a mark is made at the jig fixing position, and the product is pulled at a pulling rate of 20 mm / min until the jig distance reaches 40 mm (L1), after which the jig is released from the tester and the length (L4) between the marks is measured after 30 minutes have passed. The elongation recovery rate (%) calculated using the following formula is 95% or more. <1> ~ <3> 2-cyanoacrylate adhesive composition according to any one of the above. Elongation recovery rate (%): {(L1-L4) / (L1-L0)}×100 <5> The peel adhesive strength (N / cm) of the 2-cyanoacrylate adhesive composition to an ethylene propylene diene rubber (EPDM) substrate, measured in accordance with JIS K 6854-3:1999, is represented by As1. When the peel adhesive strength (N / cm) of the 2-cyanoacrylate adhesive composition obtained by removing the polyfunctional cyanoacrylate compound from the 2-cyanoacrylate adhesive composition from which the peel adhesive strength As1 was measured is defined as As2, the following formula is satisfied: <1> ~ <4> 2-cyanoacrylate adhesive composition according to any one of the above. (As1-As2 / As2)×100≧150% <6> The polyfunctional cyanoacrylate compound is contained in an amount of 0.01 to 50 parts by mass relative to 100 parts by mass of the 2-cyanoacrylate compound. <1> ~ <5> 2-cyanoacrylate adhesive composition according to any one of the above. <7> The 2-cyanoacrylate compound has an ether bond. <1> ~ <6> 2. The 2-cyanoacrylate adhesive composition according to any one of claims 1 to 10. <8> The 2-cyanoacrylate compound has two or more of the ether bonds. <7> 2. The 2-cyanoacrylate adhesive composition according to claim 1. <9> The 2-cyanoacrylate compound includes a compound represented by the following formula (1): <1> ~ <8> 2-cyanoacrylate adhesive composition according to any one of the above.

[0009] [ka]

[0010] In formula (1), L 1 are each independently -CH2CH2-, -CH2CH2CH2-, -CH(R 1 )CH2- or -CH2CH(R 1 )-, R 1 represents a linear or branched alkyl group having 1 to 6 carbon atoms which may have a substituent, R 2 represents a linear or branched alkyl group having 1 to 8 carbon atoms which may have a substituent, p represents an integer of 1 to 5; <10> The 2-cyanoacrylate compound has a maximum loss tangent (tanδ(max)) at a temperature of 65°C or lower. <1> ~ <9> 2-cyanoacrylate adhesive composition according to any one of the above. <11> The polyfunctional cyanoacrylate compound includes at least one of a biscyanoacrylate compound and a triscyanoacrylate compound. <1> ~ <10> 2-cyanoacrylate adhesive composition according to any one of the above. <12> The molecular weight or number average molecular weight of the polyfunctional cyanoacrylate compound is 200 to 50,000. <1> ~ <11> 2-cyanoacrylate adhesive composition according to any one of the above. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to provide a 2-cyanoacrylate adhesive composition that exhibits an excellent increase in peel adhesive strength of the cured product to rubbers such as EPDM. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments for carrying out the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. In the following embodiments, components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and do not limit the present disclosure.

[0013] In the present disclosure, numerical ranges indicated using "to" include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in the present disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with the value shown in the synthesis examples. Also, in the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.

[0014] (2-cyanoacrylate adhesive composition) The 2-cyanoacrylate adhesive composition of the present disclosure contains a 2-cyanoacrylate compound and a polyfunctional cyanoacrylate compound, and the cured product obtained by homopolymerizing the 2-cyanoacrylate compound has a storage modulus of 1.0 × 10 at 25°C. 7 Pa or less.

[0015] As a result of extensive research, the inventors have found that by adopting the above-mentioned configuration, it is possible to provide a 2-cyanoacrylate adhesive composition that exhibits an excellent increase in the peel adhesion strength of the cured product relative to rubbers such as EPDM. The mechanism of action of this excellent effect is not clear, but is presumed as follows. The storage modulus of the homopolymerized cured product of the 2-cyanoacrylate adhesive composition at 25°C is 1.0 × 10 7 By including a 2-cyanoacrylate compound (hereinafter, a cured product obtained by homopolymerizing a 2-cyanoacrylate compound) having a viscosity of 100 Pa or less (hereinafter, a cured product obtained by homopolymerizing a 2-cyanoacrylate compound is also referred to as a homopolymer) and a polyfunctional cyanoacrylate compound, the entropy elasticity of the cured product of the 2-cyanoacrylate adhesive composition of the present disclosure (hereinafter, simply referred to as the cured product) is improved, and therefore, it is presumed that the peel adhesion strength and its rate of increase of the cured product to rubbers such as EPDM are improved.

[0016] <2-cyanoacrylate compounds> The 2-cyanoacrylate adhesive composition of the present disclosure has a storage modulus at 25°C of 1.0 × 10 7 The 2-cyanoacrylate adhesive composition of the present disclosure may contain two or more types of the specific 2-cyanoacrylate compounds. The storage modulus of the homopolymerized cured product of the 2-cyanoacrylate adhesive composition at 25°C is 1.0 × 10 7 The elongation recovery rate of the cured product tends to be improved by containing a 2-cyanoacrylate compound (hereinafter, a cured product obtained by homopolymerizing a 2-cyanoacrylate compound is also referred to as a homopolymer) having a viscosity of 100 Pa or less and a polyfunctional cyanoacrylate compound. This is presumably because the entropy elasticity of the cured product of the 2-cyanoacrylate adhesive composition of the present disclosure (hereinafter, simply referred to as the cured product) is improved, which promotes deformation of the cured product to its pre-elongation state and improves the elongation recovery rate of the cured product.

[0017] From the viewpoint of the increase rate of peel adhesive strength of the cured product to rubbers such as EPDM and the elongation recovery rate of the cured product, the storage modulus of the homopolymer at 25°C is 9.0 × 10 6It is preferable that the pressure is 0.01 Pa or less. The lower limit of the storage modulus of the homopolymer at 25°C is not particularly limited, but may be, for example, 1.0 × 10 4 It can be set to Pa or more.

[0018] In the present disclosure, the storage modulus of a cured product obtained by homopolymerizing a specific 2-cyanoacrylate compound is measured as follows. The 2-cyanoacrylate compound is injected between the tools of a dynamic viscoelasticity measuring device coated with triethanolamine, and then the storage modulus is 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. Once it is confirmed that there is no change in the storage modulus of the 2-cyanoacrylate compound, this is taken as a cured product of the 2-cyanoacrylate compound. Next, using the above cured product, the storage modulus of the cured product is measured by shear in the range of -50°C to 150°C under conditions of a frequency of 1 Hz, a temperature rise rate of 2°C / min, and a relative humidity of 50%, and the storage modulus of the cured product at 25°C is determined. As the dynamic viscoelasticity measuring device, an MCR301 manufactured by Anton Paar or a device of the same level can be used.

[0019] From the viewpoint of the rate of increase in peel adhesive strength of the cured product against rubbers such as EPDM and the elongation recovery rate of the cured product, the temperature at which the maximum value of the loss tangent (tanδ(max)) of the cured product obtained by homopolymerizing the specific 2-cyanoacrylate compound is exhibited is preferably 65°C or lower, more preferably 55°C or lower, even more preferably 45°C or lower, and particularly preferably 40°C or lower. The lower limit of the temperature is not particularly limited, but can be, for example, −20° C. or higher.

[0020] In the present disclosure, the temperature at which the loss tangent of a specific 2-cyanoacrylate compound exhibits a maximum value is measured as follows. A specific 2-cyanoacrylate compound is injected between the tools of a dynamic viscoelasticity measuring device coated with triethanolamine, and then the storage modulus is 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. After confirming that the storage modulus of the specific 2-cyanoacrylate compound has ceased to change, this is designated as a cured product of the specific 2-cyanoacrylate compound. Using the cured product, a dynamic viscoelastic spectrum is obtained in the range of -50°C to 150°C under conditions of a frequency of 1 Hz and a heating rate of 2°C / min, and the temperature at which the loss tangent (tanδ) reaches its maximum is measured. If two or more peaks are observed, the loss tangent (tanδ) of the largest peak is designated as the maximum value. The dynamic viscoelasticity measuring device that can be used is as described above.

[0021] From the viewpoints of the increase rate of peel adhesive strength of the cured product to rubbers such as EPDM and the elongation recovery rate of the cured product, the specific 2-cyanoacrylate compound preferably has an ether bond. From the same viewpoints, the specific 2-cyanoacrylate compound preferably has two or more ether bonds, more preferably two to five, even more preferably two to four, and particularly preferably two or three. The 2-cyanoacrylate adhesive composition of the present disclosure may contain two or more specific 2-cyanoacrylate compounds having different numbers of ether bonds.

[0022] From the viewpoint of the increase rate of peel adhesive strength of the cured product to rubber such as EPDM and the elongation recovery rate of the cured product, the specific 2-cyanoacrylate compound preferably contains a compound represented by the following formula (1).

[0023] [ka]

[0024] In formula (1), L 1 are each independently -CH2CH2-, -CH2CH2CH2-, -CH(R 1)CH2- or -CH2CH(R 1 )-, and from the viewpoint of the increase rate of peel adhesive strength of the cured product to rubbers such as EPDM and the elongation recovery rate of the cured product, -CH2CH2-, -CH(R 1 )CH2- or -CH2CH(R 1 )-, and preferably represents -CH(R 1 )CH2- or -CH2CH(R 1 )- is more preferred.

[0025] In formula (1), R 1 R represents an alkyl group having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms, which may have a substituent, and may be a linear or branched alkyl group. Examples of the substituent include an aryl group, a halogen atom, an alkoxy group, an aryloxy group, a cyano group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyl group, and an acyloxy group. 1 Examples of such groups include a methyl group, an ethyl group, a propyl group, and a butyl group. From the viewpoint of the increase rate of the peel adhesive strength of the cured product relative to rubbers such as EPDM and the elongation recovery rate of the cured product, a methyl group or an ethyl group is preferred, and a methyl group is more preferred.

[0026] In formula (1), R 2 represents an alkyl group having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, which may have a substituent, and may be a linear or branched alkyl group. 1 Examples of the substituents include those mentioned above. R in Equation (1) 2 From the viewpoint of the rate of increase in peel adhesive strength of the cured product relative to rubber such as EPDM and the elongation recovery rate of the cured product, is more preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group, an ethyl group, an n-propyl group or an isopropyl group, even more preferably a methyl group or an ethyl group, and particularly preferably a methyl group.

[0027] In formula (1), p represents an integer of 1 to 5, and from the viewpoint of the increase rate of peel adhesive strength of the cured product to rubbers such as EPDM and the elongation recovery rate of the cured product, it is preferably an integer of 1 to 4, more preferably an integer of 1 to 3, and even more preferably 2 or 3.

[0028] Specific examples of the compound represented by formula (1) include 2-(2-methoxyethoxy)ethyl, 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-methoxy-2-methylethoxy)ethyl, 2-(2-ethoxy-1-methylethoxy)ethyl, )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, 2-(2-hexyloxy-2-methylethoxy)propyl-1-yl,Examples of 2-cyanoacrylate esters include 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, tetrapropylene glycol monomethyl ether, tetrapropylene glycol monoethyl ether, tetrapropylene glycol monopropyl ether, tetrapropylene glycol monobutyl ether, and tetrapropylene glycol monohexyl ether. Among the above, from the viewpoint of the increase in peel adhesive strength of the cured product against rubber such as EPDM and the elongation recovery rate of the cured product, 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-cyanoacrylates are preferred, and 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-cyanoacrylates are more preferred.

[0029] From the viewpoint of the increase rate of peel adhesive strength of the cured product against rubbers such as EPDM and the elongation recovery rate of the cured product, the content of the specific 2-cyanoacrylate compound relative to the total mass of the 2-cyanoacrylate adhesive composition is preferably 50 mass% or more, more preferably 60 mass% or more, even more preferably 70 mass% or more, and most preferably 80 mass% or more. The upper limit of the content of the specific 2-cyanoacrylate compound is not particularly limited, but can be, for example, 99.9 mass % or less.

[0030] When the specific 2-cyanoacrylate compound contains a compound represented by formula (1), from the viewpoints of the increase rate of peel adhesive strength of the cured product against rubbers such as EPDM and the elongation recovery rate of the cured product, the content of the compound represented by formula (1) relative to the total mass of the specific 2-cyanoacrylate compound contained in the 2-cyanoacrylate adhesive composition is preferably 70 mass% or more, more preferably 80 mass% or more, even more preferably 90 mass% or more, particularly preferably 95 mass% or more, and may even be 100 mass%.

[0031] <Multifunctional cyanoacrylate compounds> The 2-cyanoacrylate adhesive composition of the present disclosure contains a multifunctional cyanoacrylate compound. The 2-cyanoacrylate adhesive composition of the present disclosure may contain two or more types of multifunctional cyanoacrylate compounds. Furthermore, from the viewpoint of the increase rate of peel adhesive strength of the cured product relative to rubber such as EPDM and the elongation recovery rate of the cured product, the polyfunctional cyanoacrylate compound is preferably a polyfunctional 2-cyanoacrylate compound. In the present disclosure, a polyfunctional cyanoacrylate compound refers to a compound having two or more cyanoacryloyl groups.

[0032] Examples of polyfunctional cyanoacrylate compounds include 2-cyanoacrylate esters of 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. From the viewpoint of flexibility and toughness of the cured product, the polyfunctional cyanoacrylate compound preferably contains at least one selected from the group consisting of polyoxyalkylene polyols, polyester polyols, polycarbonate polyols, polyurethane polyols, polyamide polyols, polyester polyamide polyols, acrylic polyols, polybutadiene polyols, hydrogenated polybutadiene polyols, polyisoprene polyols, and hydrogenated polyisoprene polyols, and more preferably contains at least one 2-cyanoacrylate ester of a compound selected from the group consisting of polyoxyalkylene polyols, polyester polyols, polycarbonate polyols, polybutadiene polyols, hydrogenated polybutadiene polyols, polyisoprene polyols, and hydrogenated polyisoprene polyols. Among the above, the polyfunctional cyanoacrylate compound preferably contains polyoxyalkylene polyol, and more preferably contains polyoxypropylene glycol. The polyfunctional cyanoacrylate compound may also contain glycerin ether.

[0033] The polyoxyalkylene polyol is not particularly limited, but examples thereof include polyethylene glycol, polyethylene triol, polyethylene tetraol, polypropylene glycol, polypropylene triol, polypropylene tetraol, polytetramethylene glycol, and copolymers with polyols or other glycols. The polyester polyol is not particularly limited, but examples thereof include general polyester polyols produced by the reaction of a dibasic acid such as adipic acid with a glycol, triol, or the like, and polycaprolactone polyols obtained by ring-opening polymerization of caprolactone. The polycarbonate diol is not particularly limited, but may be a general polycarbonate diol derived from ethylene carbonate or a copolymer of carbonate and glycol. Furthermore, 2-cyanoacrylate esters of polybutadiene polyol, hydrogenated polybutadiene polyol, polyisoprene polyol, and hydrogenated polyisoprene polyol are preferred from the viewpoint of warm water resistance as well as flexibility and toughness of the cured product.

[0034] The polyfunctional cyanoacrylate preferably contains at least one of a biscyanoacrylate compound and a triscyanoacrylate compound. From the viewpoint of the increase rate of peel adhesive strength of the cured product to rubbers such as EPDM and the elongation recovery rate of the cured product, biscyanoacrylate compounds are preferred to triscyanoacrylate compounds. From the viewpoint of the increase rate of peel adhesive strength of the cured product to rubbers such as EPDM and the elongation recovery rate of the cured product, the biscyanoacrylate compound is preferably an alkanediol biscyanoacrylate compound or a polyoxyalkylene polyol biscyanoacrylate compound. From the viewpoint of the increase rate of peel adhesive strength of the cured product to rubber such as EPDM and the elongation recovery rate of the cured product, the triscyanoacrylate compound is preferably a polyoxyalkylene polyol tricyanoacrylate compound. The aliphatic group of the alkanediol biscyanoacrylate compound preferably has 2 to 18 carbon atoms, and more preferably has 4 to 12 carbon atoms. The aliphatic group may be linear, branched, or cyclic. Examples of the alkanediol biscyanoacrylate compound include 1,6-hexanediol biscyanoacrylate, 1,4-butanediol biscyanoacrylate, 1,8-octanediol biscyanoacrylate, 1,9-nonanediol biscyanoacrylate, 1,10-decanediol biscyanoacrylate, 1,12-dodecanediol biscyanoacrylate, 1,5-pentanediol biscyanoacrylate, 1,16-hexadecanediol biscyanoacrylate, and 1,18-octadecanediol biscyanoacrylate. Among the above, from the viewpoints of the increase rate of peel adhesive strength of the cured product relative to rubbers such as EPDM and the elongation recovery rate of the cured product, 1,6-hexanediol-biscyanoacrylate, 1,8-octanediol-biscyanoacrylate, 1,9-nonanediol-biscyanoacrylate, 1,10-decanediol-biscyanoacrylate, 1,12-dodecanediol-biscyanoacrylate, 1,16-hexadecanediol-biscyanoacrylate, and 1,18-octadecanediol-biscyanoacrylate are preferred, and 1,6-hexanediol-biscyanoacrylate or 1,10-decanediol-biscyanoacrylate is more preferred. Examples of polyoxyalkylene polyols that constitute the polyoxyalkylene polyol biscyanoacrylate compound or polyoxyalkylene polyol tricyanoacrylate compound include polyoxypropylene glycol (PPG), polyoxyethylene glycol, polyoxytetramethylene glycol, polyoxyethylene polyoxypropylene glycol, polyoxyethylene polyoxytetramethylene glycol, and polyoxypropylene polyoxytetramethylene glycol. Among the above, polyoxypropylene glycol (PPG)-biscyanoacrylate or polyoxypropylene glycol (PPG)-triscyanoacrylate is preferred from the viewpoint of the increase rate of peel adhesive strength of the cured product to rubbers such as EPDM and the elongation recovery rate of the cured product.

[0035] From the viewpoint of the increase rate of peel adhesive strength of the cured product to rubbers such as EPDM and the elongation recovery rate of the cured product, the molecular weight or number average molecular weight (Mn) of the polyfunctional cyanoacrylate compound is preferably 200 to 50,000, more preferably 200 to 25,000, and even more preferably 200 to 23,000. In the present disclosure, Mn is a value calculated in terms of standard polystyrene obtained by gel permeation chromatography (GPC).

[0036] From the viewpoint of the rate of increase in peel adhesive strength of the cured product against rubbers such as EPDM and the elongation recovery rate of the cured product, the content of the polyfunctional cyanoacrylate compound per 100 parts by mass of the 2-cyanoacrylate compound contained in the 2-cyanoacrylate adhesive composition of the present disclosure is preferably 0.01 parts by mass to 50 parts by mass, more preferably 0.1 parts by mass to 30 parts by mass, even more preferably 0.5 parts by mass to 20 parts by mass, and particularly preferably 0.7 parts by mass to 10 parts by mass.

[0037] When the polyfunctional cyanoacrylate contains at least one of a biscyanoacrylate compound and a triscyanoacrylate compound, from the viewpoints of the increase in peel adhesive strength of the cured product against rubbers such as EPDM and the elongation recovery rate of the cured product, the sum of the contents of the biscyanoacrylate compound and the triscyanoacrylate compound relative to the total mass of the polyfunctional cyanoacrylate contained in the 2-cyanoacrylate adhesive composition is preferably 70 mass% or more, more preferably 80 mass% or more, even more preferably 90 mass% or more, particularly preferably 95 mass% or more, and may even be 100 mass%.

[0038] <Other ingredients> The 2-cyanoacrylate adhesive composition of the present disclosure may contain components other than the specific 2-cyanoacrylate compound and the polyfunctional cyanoacrylate compound, provided that the properties of the adhesive composition are not impaired. Other components include 2-cyanoacrylate compounds other than the specific 2-cyanoacrylate compound, stabilizers, curing accelerators, plasticizers, thickeners, particles, colorants, fragrances, solvents, strength improvers, and the like.

[0039] Examples of 2-cyanoacrylate compounds other than the specific 2-cyanoacrylate compounds include esters of 2-cyanoacrylic acid such as methyl, ethyl, chloroethyl, n-propyl, i-propyl, allyl, propargyl, n-butyl, i-butyl, n-pentyl, n-hexyl, cyclohexyl, phenyl, tetrahydrofurfuryl, heptyl, 2-ethylhexyl, n-octyl, 2-octyl, n-nonyl, oxononyl, n-decyl, n-dodecyl, methoxyethyl, methoxypropyl, methoxyisopropyl, methoxybutyl, ethoxyethyl, ethoxypropyl, ethoxyisopropyl, propoxymethyl, propoxyethyl, isopropoxyethyl, propoxypropyl, butoxymethyl, butoxyethyl, butoxypropyl, butoxyisopropyl, butoxybutyl, 2,2,2-trifluoroethyl, and hexafluoroisopropyl. These 2-cyanoacrylate compounds may be used alone or in combination of two or more.

[0040] Examples of stabilizers include (1) sulfur dioxide and aliphatic sulfonic acids such as 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 HBF and trialkyl borates, and (2) radical polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, t-butylcatechol, catechol, and pyrogallol. These stabilizers may be used alone or in combination of two or more.

[0041] Any curing accelerator can be used as long as it accelerates the anionic polymerization of the 2-cyanoacrylate adhesive composition. Examples of the curing accelerator include polyether compounds, calixarenes, thiacalixarenes, pyrogallolarenes, onium salts, etc. These curing accelerators may be used alone or in combination of two or more.

[0042] Examples of the plasticizer 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-ethylhexyl cyclohexyl carboxylate, diisobutyl fumarate, diisobutyl maleate, triglyceride caproate, 2-ethylhexyl benzoate, and dipropylene glycol dibenzoate. Among these, acetyl tributyl citrate, dimethyl adipate, dimethyl phthalate, 2-ethylhexyl benzoate, and dipropylene glycol dibenzoate are preferred because they have good compatibility with 2-cyanoacrylate compounds and high plasticizing efficiency. These plasticizers may be used alone or in combination of two or more.

[0043] Examples of thickeners include polymethyl methacrylate, copolymers of methyl methacrylate and acrylic esters, copolymers of methyl methacrylate and other methacrylic esters, acrylic rubber, polyvinyl acetate, polyvinyl chloride, polyurethane resins, polyamide resins, polystyrene, cellulose esters, polyalkyl-2-cyanoacrylates, ethylene-vinyl acetate copolymers, etc. These thickeners may be used alone or in combination of two or more.

[0044] The 2-cyanoacrylate adhesive composition of the present disclosure may contain particles to the extent that the properties of the composition are not impaired. This allows the thickness of the adhesive layer formed by using the 2-cyanoacrylate adhesive composition to be adjusted. The average particle size of the particles is preferably 10 μm to 200 μm, more preferably 15 μm to 200 μm, and even more preferably 15 μm to 150 μm. The material of the particles is not particularly limited as long as it is insoluble in the 2-cyanoacrylate compound used and does not cause deterioration such as polymerization. Examples of the 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 fiber; silicone compounds; and organic-inorganic composite particles comprising an organic polymer skeleton and a polysiloxane skeleton. Furthermore, the particle content is not particularly limited, but from the standpoint of curing speed, adhesive strength, etc., the particle content relative to 100 mass parts of the 2-cyanoacrylate compound contained in the 2-cyanoacrylate adhesive composition of the present disclosure is preferably 0.1 to 10 mass parts, more preferably 1 to 5 mass parts, and even more preferably 1 to 3 mass parts. In the present disclosure, the average particle size of particles is a volume-based average value measured by a laser diffraction particle size distribution analyzer.

[0045] <Elongation Recovery Rate of the 2-Cyanoacrylate Adhesive Composition of the Present Disclosure> A cured product of the above-described 2-cyanoacrylate adhesive composition of the present disclosure, having a width of 5 mm, a length of 50 mm, and a thickness of 1 mm, is fixed to a tensile testing machine with a jig distance of 20 mm (L0), a mark is made at the jig fixing position, and the product is pulled at a pulling rate of 20 mm / min until the jig distance reaches 40 mm (L1). After that, the jig is released and the length between the marks (L2) is measured after 1 minute has passed. The elongation recovery rate (%) calculated using the following formula is preferably 70% or more, more preferably 80% or more, even more preferably 90% or more, and particularly preferably 95% or more. The elongation recovery rate is measured in an environment of 25°C and 50% relative humidity. Elongation recovery rate (%): {(L1-L2) / (L1-L0)}×100

[0046] A cured product of the above-described 2-cyanoacrylate adhesive composition of the present disclosure, having a width of 5 mm, a length of 50 mm, and a thickness of 1 mm, is fixed to a tensile testing machine with a jig distance of 20 mm (L0), a mark is made at the jig fixing position, and the product is pulled at a pulling rate of 20 mm / min until the jig distance reaches 40 mm (L1). After that, the jig is released and the length between the marks (L3) is measured after 5 minutes have passed. The elongation recovery rate (%) calculated using the following formula is preferably 80% or more, more preferably 90% or more, even more preferably 95% or more, and particularly preferably 97% or more. The elongation recovery rate is measured in an environment of 25°C and 50% relative humidity. Elongation recovery rate (%): {(L1-L3) / (L1-L0)}×100

[0047] A cured product of the above-described 2-cyanoacrylate adhesive composition of the present disclosure, having a width of 5 mm, a length of 50 mm, and a thickness of 1 mm, is fixed to a tensile testing machine with a jig distance of 20 mm (L0), a mark is made at the jig fixing position, and the product is pulled at a pulling rate of 20 mm / min until the jig distance reaches 40 mm (L1). After that, the jig is released and the length between the marks (L4) is measured after 30 minutes have passed. The elongation recovery rate (%) calculated using the following formula is preferably 95% or more, more preferably 97% or more, and even more preferably 99% or more. The elongation recovery rate is measured in an environment of 25°C and 50% relative humidity. Elongation recovery rate (%): {(L1-L4) / (L1-L0)}×100

[0048] The tensile tester used to measure the elongation recovery rate may be a Strograph V20-C manufactured by Toyo Seiki Seisakusho Co., Ltd. or a device of the same level. The cured product used in measuring the elongation recovery rate is produced as follows. First, a silicone rubber mold with a thickness of 1 mm is placed on a release polyethylene terephthalate (PET) film. Next, 1 μL of triethanolamine is added to 1 g of the 2-cyanoacrylate adhesive composition of the present disclosure, and after stirring, the mixture is poured into the mold. After pouring the 2-cyanoacrylate adhesive composition, the mold and the adhesive composition are covered with the release PET film prepared separately, and the mixture is sandwiched between glass plates. The mixture is then left to stand at 25°C and a relative humidity of 50% for 24 hours to allow it to completely harden. After curing, the mold and release PET film are removed to obtain a cured product measuring 5 mm in width, 50 mm in length, and 1 mm in thickness.

[0049] <Peel adhesion strength of the 2-cyanoacrylate adhesive composition of the present disclosure> The peel adhesion strength (N / cm) of the 2-cyanoacrylate adhesive composition of the present disclosure to an ethylene propylene diene rubber (EPDM) substrate, measured in accordance with JIS K 6854-3:1999, is represented by As1. When the peel adhesion strength (N / cm) of a 2-cyanoacrylate adhesive composition obtained by removing the polyfunctional cyanoacrylate compound from the above 2-cyanoacrylate adhesive composition from which the peel adhesion strength As1 was measured is defined as As2, it is preferable that the following formula (A) is satisfied, it is more preferable that the following formula (B) is satisfied, and it is even more preferable that the following formula (C) is satisfied. The increase rate of peel adhesive strength can be calculated using the following formulas (A) to (C). (As1-As2 / As2)×100≧150% (A) (As1-As2 / As2)×100≧200% (B) (As1-As2 / As2)×100≧250% (C)

[0050] More specifically, the peel adhesion strength is measured as follows. First, 1 g of the 2-cyanoacrylate adhesive composition of the present disclosure is applied to an EPDM substrate, and the composition is left to stand at a temperature of 23°C and a relative humidity of 50% for 7 days to allow it to cure completely. After curing, the T-peel adhesive strength (N / cm) is measured using a tensile tester in accordance with JIS K 6854-3:1999 at a pulling speed of 100 mm / min. The T-peel adhesive strength is measured in an environment of 25°C and 50% relative humidity. The tensile tester may be the same as that used to measure the elongation recovery rate.

[0051] <Uses of the 2-cyanoacrylate adhesive composition of the present disclosure> The 2-cyanoacrylate adhesive composition of the present disclosure can be used in a variety of applications, including construction applications, automotive applications, and electrical and electronic material applications. Examples of construction applications include elastic adhesives for construction, adhesives for double-glazing, adhesives for artificial marble, etc. Examples of electrical and electronic material applications include resins for sealing semiconductors, insulating materials for printed wiring boards, insulating coating materials for electric wires and cables, coating agents for electronic components, potting agents for electronic components, and sealers for electrical equipment. The 2-cyanoacrylate adhesive composition of the present disclosure can also be used for packings, O-rings, etc. Specific examples include waterproof gaskets, insect-proof gaskets, vibration-proof, sound-absorbing and air-sealing materials for cleaners, drip-proof covers for electric water heaters, waterproof gaskets, heater gaskets, electrode gaskets, safety valve diaphragms, solenoid valves, waterproof gaskets for steam oven ranges and jar rice cookers, water tank gaskets, water intake valves, water receiver gaskets, heat-retaining heater gaskets, oil gaskets for combustion equipment such as steam outlet seals, O-rings, drain gaskets, air supply and intake gaskets, vibration-proof rubber, oil filler port gaskets, oil gauge gaskets, diaphragm valves, speaker gaskets and speaker edges for audio equipment. In addition, in automotive-related applications, the adhesive composition can be used for body parts such as adhesive sealants for maintaining airtightness, vibration-proofing materials for glass, and vibration-damping materials for vehicle body parts, particularly wind seal gaskets and door glass gaskets. In engine parts, the adhesive composition can be used for adhesive sealants for engine oil, etc. Furthermore, the adhesive composition of the present invention can also be used in gasket methods [Mold-In-Place Gasket (MIPG), Formed-In-Place Gasket (FIPG), Cured-In-Place Gasket (CIPG)] in which a liquid sealant is automatically applied by a robot or the like on an assembly line for electric / electronic parts and automotive parts to form an adhesive seal.

[0052] Furthermore, the 2-cyanoacrylate adhesive composition of the present disclosure can be suitably used for adherends made of resin or metal, more suitably used for rubber, and particularly suitably used for EPDM. [Example]

[0053] The above-described embodiment will be specifically described below using examples, but the above-described embodiment is not limited to these examples. In the following, "parts" means "parts by mass" unless otherwise specified.

[0054] Various physical properties were measured as follows.

[0055] <Storage modulus at 25°C of a cured product obtained by homopolymerizing a 2-cyanoacrylate compound> The 2-cyanoacrylate compound was injected between the triethanolamine-coated dynamic viscoelasticity measuring jig, and then the storage modulus was measured using a dynamic viscoelasticity measuring device (manufactured by Anton Paar, product name "MCR301") under the conditions of a frequency of 1 Hz, a temperature of 25°C, and a thickness of 300 μm. After confirming that the storage modulus of the 2-cyanoacrylate compound had ceased to change, this was designated as a cured product of the 2-cyanoacrylate compound. Using the cured product, the storage modulus of the cured product was measured by shearing in the range of -50°C to 150°C under conditions of a frequency of 1 Hz, a heating rate of 2°C / min, and a relative humidity of 50%, and the storage modulus of the cured product at 25°C was calculated. Table 1 shows the storage modulus at 25°C of the cured product obtained by homopolymerizing the 2-cyanoacrylate compound used in each example and comparative example (referred to as the storage modulus of the 2-cyanoacrylate compound in the table).

[0056] <Temperature at which the loss tangent of 2-cyanoacrylate compounds exhibits its maximum value (tanδ(max))> The 2-cyanoacrylate compound was injected between the triethanolamine-coated dynamic viscoelasticity measuring jig, and then the storage modulus was measured using a dynamic viscoelasticity measuring device (manufactured by Anton Paar, product name "MCR301") under the conditions of a frequency of 1 Hz, a temperature of 25°C, and a thickness of 300 μm. After confirming that the storage modulus of the 2-cyanoacrylate compound had ceased to change, this was designated as a cured product of the 2-cyanoacrylate compound. Using the cured product, a dynamic viscoelastic spectrum was obtained in the range of -50°C to 150°C at a frequency of 1 Hz and a heating rate of 2°C / min, and the temperature at which the loss tangent (tanδ) reached its maximum was measured. When two or more peaks were observed, the loss tangent (tanδ) corresponding to the largest peak was designated as the maximum value.

[0057] (Examples 1 to 14) A 2-cyanoacrylate adhesive composition was produced by blending 100 parts of a 2-cyanoacrylate compound shown in Table 1 with a polyfunctional cyanoacrylate compound shown in Table 1 in an amount specified in Table 1, and stirring until homogenous.

[0058] (Comparative Example 1) The 2-cyanoacrylate compounds listed in Table 1 were used as adhesive compositions.

[0059] (Comparative Examples 2 to 5) An adhesive composition was produced by blending 100 parts of a 2-cyanoacrylate compound shown in Table 1 with a polyfunctional cyanoacrylate compound shown in Table 1 in an amount specified in Table 1, and stirring until homogenous.

[0060] (Comparative Example 6) The 2-cyanoacrylate compounds listed in Table 1 were used as adhesive compositions.

[0061] (Comparative Examples 7 to 10) An adhesive composition was produced by blending 100 parts of a 2-cyanoacrylate compound shown in Table 1 with a polyfunctional cyanoacrylate compound shown in Table 1 in an amount specified in Table 1, and stirring until homogenous.

[0062] (Comparative Examples 11 and 12) The 2-cyanoacrylate compounds listed in Table 1 were used as adhesive compositions.

[0063] Details of the abbreviations for the polyfunctional cyanoacrylates in Table 1 are as follows: HBCA: Bifunctional 2-cyanoacrylate compound (1,6-hexanediol-biscyanoacrylate), molecular weight: 276.29 DBCA: Bifunctional 2-cyanoacrylate compound (1,10-decanediol-biscyanoacrylate), molecular weight: 332.40 PPG4000TCA: Trifunctional 2-cyanoacrylate compound (PPG(Mn4000)-triscyanoacrylate), Mn4,640 PPG10000BCA: Bifunctional 2-cyanoacrylate compound (PPG(Mn10000)-biscyanoacrylate), Mn19,700

[0064] HBCA was synthesized by the following method. A 500 mL flask equipped with a stirrer, a thermometer, a Liebig condenser, a nitrogen inlet tube, and a dropping funnel was charged with 4.80 g (41.6 mmol) of cyanoacrylic acid chloride and 270 mL of benzene. The reaction system was then heated to 60°C, and a solution of 5.22 g of 1,6-hexanediol (reagent) dissolved in 5 mL of benzene was added while blowing nitrogen gas through the nitrogen inlet tube. The temperature was then maintained at 60°C and the mixture was stirred for 30 minutes. After cooling to 25°C, the benzene was distilled off under reduced pressure, and the mixture was recrystallized twice by cooling to -20°C in a 7 / 4 pentane / hexane mixture, yielding 5.02 g of a solid polyfunctional cyanoacrylate (HBCA). In addition, dry benzene was used as the benzene, and glassware was thoroughly dried by heating. The same applies to the following synthesis examples.

[0065] DBCA was synthesized by the following method. A 500 mL flask equipped with a stirrer, a thermometer, a Liebig condenser, a nitrogen inlet tube, and a dropping funnel was charged with 4.80 g (41.6 mmol) of cyanoacrylic acid chloride and 270 mL of benzene. The reaction system was then heated to 60°C, and a solution of 10.2 g of 1,10-decanediol (reagent) dissolved in 10 mL of benzene was added while blowing nitrogen gas through the nitrogen inlet tube. The temperature was then maintained at 60°C and the mixture was stirred for 30 minutes. After cooling to 25°C, the benzene was distilled off under reduced pressure, and the mixture was recrystallized twice by cooling to -20°C in a 7 / 4 pentane / hexane mixture, yielding 8.00 g of a solid polyfunctional cyanoacrylate (DBCA).

[0066] PPG4000TCA was synthesized by the following method. A 500 mL flask equipped with a stirrer, a thermometer, a Liebig condenser, a nitrogen inlet tube, and a dropping funnel was charged with 2.40 g (20.8 mmol) of cyanoacrylic acid chloride and 135 mL of benzene. The reaction system was then heated to 60°C, and a solution of 25.2 g of polyoxypropylene glycol (number average molecular weight: 4000 (catalog value), polyether triol type, manufactured by ADEKA Corporation, trade name "ADEKA Polyether G-4000") dissolved in 16 mL of benzene was added while blowing nitrogen gas through the nitrogen inlet tube. The temperature was then maintained at 60° C. and the mixture was stirred for 30 minutes. After that, the mixture was cooled to 25° C., and the benzene was distilled off under reduced pressure to obtain 28.1 g of a colorless, viscous oily polyfunctional cyanoacrylate (PPG4000TCA).

[0067] PPG10000BCA was synthesized by the following method. A 500 mL flask equipped with a stirrer, a thermometer, a Liebig condenser, a nitrogen inlet tube, and a dropping funnel was charged with 2.40 g (20.8 mmol) of cyanoacrylic acid chloride and 135 mL of benzene. The reaction system was then heated to 60°C, and a solution of 94.5 g of polyoxypropylene glycol [number average molecular weight: 10,000 (catalog value), both-terminal hydroxyl group type, manufactured by AGC, trade name "Preminol S-4011"] dissolved in 60 mL of benzene was added while blowing nitrogen gas through the nitrogen inlet tube. The temperature was then maintained at 60° C. and the mixture was stirred for 30 minutes. After that, the mixture was cooled to 25° C., and the benzene was distilled off under reduced pressure to obtain 97.8 g of a colorless, viscous, oily polyfunctional cyanoacrylate (PPG10000BCA).

[0068] <Evaluation of peel adhesion strength> 1 g of the adhesive composition produced in the above Examples and Comparative Examples was applied to an ethylene propylene diene rubber (EPDM) substrate (EPDM-5065 manufactured by Irumagawa Rubber Co., Ltd.), and left to stand at 23°C and a relative humidity of 50% for 7 days to allow it to completely cure. After curing, the T-peel adhesive strength (N / cm) was measured using the tensile tester in accordance with JIS K 6854-3:1999. The T-peel adhesive strength was measured in an environment of 25°C and 50% relative humidity, with a pulling speed of 100 mm / min. The measurement results are shown in Table 1.

[0069] The increase in peel adhesion strength (As1a) of the 2-cyanoacrylate adhesive composition produced in Example 1 to an EPDM substrate (As2a) of the adhesive composition produced in Comparative Example 11 to an EPDM substrate (As1a) was calculated as 270% ((As1a-As2a / As2a) x 100). The increase in peel adhesion strength was calculated in the same manner as above from the peel adhesion strength of the 2-cyanoacrylate adhesive compositions produced in Examples 2 to 7 to an EPDM substrate and the peel adhesion strength of the adhesive composition produced in Comparative Example 11 to an EPDM substrate, and the results were 242%, 247%, 201%, 278%, 163%, and 156%, respectively. Furthermore, the increase in peel adhesion strength ((As1b-As2b / As2b) x 100) was calculated from the peel adhesion strength (As1b) of the 2-cyanoacrylate adhesive composition produced in Example 8 to an EPDM substrate and the peel adhesion strength (As2b) of the adhesive composition produced in Comparative Example 12 to an EPDM substrate, and was found to be 372%. The increase in peel adhesion strength was calculated in the same manner as above from the peel adhesion strength of the 2-cyanoacrylate adhesive compositions produced in Examples 9 to 14 to an EPDM substrate and the peel adhesion strength of the adhesive composition produced in Comparative Example 12 to an EPDM substrate, and the results were 432%, 440%, 410%, 521%, 270%, and 206%, respectively. Furthermore, the increase in peel adhesion strength ((As1c-As2c / As2c) x 100) was calculated from the peel adhesion strength (As1c) of the adhesive composition produced in Comparative Example 1 to an EPDM substrate and the peel adhesion strength (As2c) of the adhesive composition produced in Comparative Example 2 to an EPDM substrate, and was found to be 2%. The increase in peel adhesion strength was calculated in the same manner as above from the peel adhesion strength to an EPDM substrate of the adhesive composition produced in Comparative Example 3 and the peel adhesion strength to an EPDM substrate of the adhesive composition produced in Comparative Example 1, and was found to be 8%. Furthermore, the increase in peel adhesion strength ((As1d-As2d / As2d) x 100) was calculated from the peel adhesion strength (As1d) of the adhesive composition produced in Comparative Example 7 to an EPDM substrate and the peel adhesion strength (As2d) of the adhesive composition produced in Comparative Example 6 to an EPDM substrate, and was found to be 137%. The increase in peel adhesion strength was calculated in the same manner as above from the peel adhesion strength to an EPDM substrate of the adhesive compositions produced in Comparative Examples 8 to 10 and the peel adhesion strength to an EPDM substrate of the adhesive composition produced in Comparative Example 6, and the results were 144%, 94%, and 81%, respectively.

[0070] From the above, it can be seen that the 2-cyanoacrylate adhesive compositions produced in the examples have an excellent rate of increase in peel adhesive strength to rubbers such as EPDM. The increase rate of peel adhesive strength for each example and comparative example is summarized in Table 1. In addition, Comparative Examples 1, 6, 11, and 12, which are the standards for peel adhesive strength, are all recorded as "1" in Table 1. In addition, for Comparative Examples 4 and 5, no increase in peel adhesive strength was observed, and therefore, they are entered as "-" in Table 1.

[0071] <Evaluation of elongation recovery rate> A silicone rubber mold frame with a thickness of 1 mm was placed on a release polyethylene terephthalate (PET) film (manufactured by Teijin Film Solutions Co., Ltd., product name "Purex (registered trademark) A31"). 1 μL of triethanolamine was added to 1 g of the adhesive composition produced in the above Examples and Comparative Examples, and after stirring, the mixture was poured into the above mold. After pouring the adhesive composition, the mold and the adhesive composition were covered with the above-mentioned release PET film, which had been prepared separately, and sandwiched between glass plates. The mixture was then left to stand at 25°C and a relative humidity of 50% for 24 hours to allow it to harden completely. After curing, the mold and release PET film were removed to obtain a cured product measuring 5 mm in width, 50 mm in length, and 1 mm in thickness.

[0072] Using a tensile testing machine (manufactured by Toyo Seiki Seisakusho, product name "Strograph V20-C"), the cured product was fixed at a jig distance of 20 mm (L0), and the jig fixing positions were marked. The cured product was then pulled at a tensile speed of 20 mm / min until the jig distance reached 40 mm (L1). After the jig was released, the length (L2) between the marks was measured 1 minute, 5 minutes, and 30 minutes later, and the elongation recovery rate (%) was calculated using the following formula. The calculation results are shown in Table 1. Elongation recovery rate (%): {(L1-L2) / (L1-L0)}×100

[0073] [Table 1]

[0074] Table 1 shows that the 2-cyanoacrylate adhesive compositions produced in the Examples have superior peel bond strength and peel bond strength increase rate to rubbers such as EPDM compared to the adhesive compositions produced in the Comparative Examples. It also shows that the 2-cyanoacrylate adhesive compositions produced in the Examples have superior elongation recovery rate of the cured product compared to the adhesive compositions produced in the Comparative Examples.

[0075] The disclosure of Japanese Patent Application No. 2021-115346, filed on July 12, 2021, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. Contains a 2-cyanoacrylate compound and a polyfunctional cyanoacrylate compound, The storage modulus at 25°C of the cured product obtained by homopolymerizing the 2-cyanoacrylate compound is 1.0 × 10 ７ Pa or less, the polyfunctional cyanoacrylate compound includes at least one selected from the group consisting of an alkanediol biscyanoacrylate compound and a 2-cyanoacrylic acid ester of a polyoxyalkylene polyol; 2-Cyanoacrylate adhesive compositions.

2. 2. The 2-cyanoacrylate adhesive composition according to claim 1, wherein a cured product of the 2-cyanoacrylate adhesive composition having a width of 5 mm, a length of 50 mm and a thickness of 1 mm is fixed to a tensile testing machine with a jig distance of 20 mm (L0), a mark is made at the jig fixing position, and the product is pulled at a pulling rate of 20 mm / min until the jig distance reaches 40 mm (L1), after which the jig is released from fixation and the length (L2) between the marks is measured after 1 minute has elapsed, and the elongation recovery rate (%) calculated using the following formula is 70% or more. Elongation recovery rate (%): {(L1-L2) / (L1-L0)}×100

3. 3. The 2-cyanoacrylate adhesive composition according to claim 1, wherein a cured product of the 2-cyanoacrylate adhesive composition having a width of 5 mm, a length of 50 mm and a thickness of 1 mm is fixed to a tensile tester with a jig distance of 20 mm (L0), a mark is made at the jig fixing position, and the product is pulled at a pulling rate of 20 mm / min until the jig distance reaches 40 mm (L1), after which the jig is released from fixation and the length (L3) between the marks is measured after 5 minutes have passed, and the elongation recovery rate (%) calculated using the following formula is 80% or more. Elongation recovery rate (%): {(L1-L3) / (L1-L0)}×100

4. 2. The 2-cyanoacrylate adhesive composition according to claim 1, wherein a cured product of the 2-cyanoacrylate adhesive composition having a width of 5 mm, a length of 50 mm and a thickness of 1 mm is fixed to a tensile tester with a jig distance of 20 mm (L0), a mark is made at the jig fixing position, and the product is pulled at a pulling rate of 20 mm / min until the jig distance reaches 40 mm (L1), after which the jig is released from fixation and the length (L4) between the marks is measured after 30 minutes have passed, and the elongation recovery rate (%) calculated using the following formula is 95% or more. Elongation recovery rate (%): {(L1-L4) / (L1-L0)}×100

5. The peel adhesive strength (N / cm) of the 2-cyanoacrylate adhesive composition to an ethylene propylene diene rubber substrate measured in accordance with JIS K 6854-3:1999 is designated as As1, 2. The 2-cyanoacrylate adhesive composition according to claim 1, wherein the following formula is satisfied when the peel adhesion strength (N / cm) of a 2-cyanoacrylate adhesive composition obtained by excluding the polyfunctional cyanoacrylate compound from the 2-cyanoacrylate adhesive composition from which the peel adhesion strength As1 has been measured is defined as As2: (As1-As2 / As2)×100≧150%

6. 2. The 2-cyanoacrylate adhesive composition according to claim 1, wherein the polyfunctional cyanoacrylate compound is contained in an amount of 0.01 to 50 parts by mass per 100 parts by mass of the 2-cyanoacrylate compound.

7. 2. The 2-cyanoacrylate adhesive composition according to claim 1, wherein the 2-cyanoacrylate compound has an ether bond.

8. 8. The 2-cyanoacrylate adhesive composition according to claim 7, wherein the 2-cyanoacrylate compound has two or more ether bonds.

9. 2. The 2-cyanoacrylate adhesive composition according to claim 1, wherein the 2-cyanoacrylate compound comprises a compound represented by the following formula (1): 【Chemical 1】 In formula (1), L １ are each 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, R ２ represents a linear or branched alkyl group having 1 to 8 carbon atoms which may have a substituent, p represents an integer of 1 to 5;

10. 2. The 2-cyanoacrylate adhesive composition according to claim 1, wherein the temperature at which the maximum value of the loss tangent (tan δ(max)) of a cured product obtained by homopolymerizing the 2-cyanoacrylate compound is 65°C or lower.

11. 2. The 2-cyanoacrylate adhesive composition according to claim 1, wherein the multifunctional cyanoacrylate compound comprises at least one of a biscyanoacrylate compound and a triscyanoacrylate compound.

12. 2. The 2-cyanoacrylate adhesive composition according to claim 1, wherein the polyfunctional cyanoacrylate compound has a molecular weight or number average molecular weight of 200 to 50,000.

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