2-Cyanoacrylate adhesive composition

Abstract

This invention provides a 2-cyanoacrylate-based adhesive composition with improved heat resistance for bonding. [Solution] A 2-cyanoacrylate adhesive composition containing a 2-cyanoacrylate compound including ethoxyethyl-2-cyanoacrylate, wherein the content of 2-ethoxyethanol is 0.1% by mass or less.

Description

Technical Field

[0001] The present disclosure relates to a 2-cyanoacrylate adhesive composition.

Background Art

[0002] Due to the specific anionic polymerization property of 2-cyanoacrylate ester, which is the main component of the 2-cyanoacrylate adhesive composition, polymerization is initiated by weak anions such as a small amount of moisture adhering to the surface of the adherent, and various materials can be firmly joined in a short time. Therefore, it is used as a so-called instant adhesive in a wide range of fields such as industrial, medical, and household applications.

[0003] Although the 2-cyanoacrylate adhesive composition is excellent in the property of firmly joining various materials in a short time (hereinafter referred to as "instant adhesiveness"), its cured product generally has a drawback of being inferior in heat resistance. For the purpose of improving the heat resistance of the cured product of the 2-cyanoacrylate adhesive composition, for example, Patent Document 1 describes a 2-cyanoacrylate instant adhesive in which a specific NBR-based polymer is blended with 2-cyanoacrylate, and Patent Document 2 describes a 2-cyanoacrylate-based composition in which the content of cyanoacetic acid ester is 600 mass ppm or less with respect to 100 mass parts of 2-cyanoacrylate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] While the 2-cyanoacrylate-based instant adhesive described in Patent Document 1 could increase the heat-resistant tensile shear strength, the instant adhesive properties could decrease depending on the additives used, and there were problems with the added cost of additives and the compounding process. In the 2-cyanoacrylate-based composition described in Patent Document 2, by focusing on impurities in the 2-cyanoacrylate and reducing the amount of cyanoacetic acid ester contained in the 2-cyanoacrylate, it was possible to improve the heat-resistant properties of the adhesive. However, the components other than cyanoacetic acid ester that affect the heat-resistant properties of the adhesive have not yet been clarified.

[0006] This disclosure has been made in view of the above-mentioned problems and aims to provide a 2-cyanoacrylate-based adhesive composition with improved adhesive heat resistance. [Means for solving the problem]

[0007] As a result of diligent research, the present inventors have found that it is possible to improve the heat resistance of adhesives by reducing the amount of 2-ethoxyethanol contained in a 2-cyanoacrylate adhesive composition containing ethoxyethyl-2-cyanoacrylate to a predetermined amount or less, and have completed this disclosure.

[0008] In other words, the 2-cyanoacrylate adhesive composition relating to this disclosure is as follows: 1. A 2-cyanoacrylate adhesive composition containing a 2-cyanoacrylate compound including ethoxyethyl-2-cyanoacrylate, wherein the content of 2-ethoxyethanol is 0.1% by mass or less. 2. The 2-cyanoacrylate adhesive composition described in 1. above, comprising 30% by mass or more of the ethoxyethyl-2-cyanoacrylate based on the total amount of the 2-cyanoacrylate compound. 3. A 2-cyanoacrylate adhesive composition according to 1. or 2. above, comprising an alkyl-2-cyanoacrylate having an alkyl group with 1 to 4 carbon atoms in the main chain. 4. A 2-cyanoacrylate adhesive composition for use with aluminum, as described in any of items 1 to 3 above. [Effects of the Invention]

[0009] According to this disclosure, it is possible to provide a 2-cyanoacrylate-based adhesive composition with improved heat resistance for bonding. [Modes for carrying out the invention]

[0010] One embodiment of this disclosure is described below, but this disclosure is not limited to this embodiment.

[0011] <2-Cyanoacrylate-based adhesive composition> The 2-cyanoacrylate adhesive composition of this disclosure (hereinafter also simply referred to as "the composition") is characterized by containing a 2-cyanoacrylate compound including ethoxyethyl-2-cyanoacrylate, and having a 2-ethoxyethanol content of 0.1% by mass or less. The details that define this disclosure are described below in detail.

[0012] 1,2-Cyanoacrylate compounds The 2-cyanoacrylate adhesive composition of this disclosure contains a 2-cyanoacrylate compound, including ethoxyethyl-2-cyanoacrylate, as the main adhesive component.

[0013] The content of ethoxyethyl-2-cyanoacrylate is preferably 30% by mass or more and less than 100% by mass, based on the total amount of the 2-cyanoacrylate compound, and more preferably 40% by mass or more and 90% by mass or less, and even more preferably 50% by mass or more and 70% by mass or less, from the viewpoint of adhesive heat resistance, peel strength, and flexibility of the cured product obtained.

[0014] The 2-cyanoacrylate compounds other than ethoxyethyl-2-cyanoacrylate contained in the compositions of this disclosure are not particularly limited as long as they can be used as adhesive components, but examples include alkyl-2-cyanoacrylates having an alkyl group with 1 to 4 carbon atoms.

[0015] (Alkyl-2-cyanoacrylate having an alkyl group with 1 to 4 carbon atoms) Various alkyl-2-cyanoacrylates having an alkyl group with 1 to 4 carbon atoms can be used as formulations. Specific examples include methyl-2-cyanoacrylate, ethyl-2-cyanoacrylate, n-propyl-2-cyanoacrylate, isopropyl-2-cyanoacrylate, n-butyl-2-cyanoacrylate, and isobutyl-2-cyanoacrylate. These can be used individually or in combination of two or more. Among these, at least one selected from the group consisting of n-butyl-2-cyanoacrylate, isobutyl-2-cyanoacrylate, isopropyl-2-cyanoacrylate, and ethyl-2-cyanoacrylate is preferred, with ethyl-2-cyanoacrylate being more preferred, from the viewpoint of easily improving adhesive heat resistance and bonding speed.

[0016] From the viewpoint of achieving both adhesive heat resistance and adhesive speed, the content of alkyl-2-cyanoacrylate having an alkyl group with 1 to 4 carbon atoms is preferably 5% by mass or more and less than 70% by mass, more preferably more than 10% by mass and less than 60% by mass, and even more preferably more than 30% by mass and less than 50% by mass, based on the total mass of the 2-cyanoacrylate compound.

[0017] (Other 2-cyanoacrylate compounds) In this disclosure, other 2-cyanoacrylate compounds may be used in combination with the above-mentioned 2-cyanoacrylate compounds, provided that the effects of this disclosure are not impaired. Examples of such other 2-cyanoacrylate compounds include alkyl-2-cyanoacrylates having an alkyl group with 5 or more carbon atoms, alkoxyalkyl-2-cyanoacrylates other than ethoxyethyl-2-cyanoacrylate, tetrahydrofurfuryl-2-cyanoacrylate, cyclohexyl-2-cyanoacrylate, cyclohexenyl cyanoacrylate, phenyl-2-cyanoacrylate, chloroethyl-2-cyanoacrylate, allyl-2-cyanoacrylate, propargyl-2-cyanoacrylate, benzyl-2-cyanoacrylate, 2,2,2-trifluoroethyl-2-cyanoacrylate, hexafluoroisopropyl-2-cyanoacrylate, and the like. These compounds may be used alone or in combination of two or more.

[0018] From the viewpoint of maintaining good adhesive heat resistance without impairing the curing rate, the content of the 2-cyanoacrylate compound in the composition of the present disclosure is preferably 50% by mass or more, more preferably 60% to 99.9% by mass, and even more preferably 65% to 99.9% by mass based on the total mass of the composition of the present disclosure.

[0019] 2.2-Ethoxyethanol In the 2-cyanoacrylate-based adhesive composition of the present disclosure, the content of 2-ethoxyethanol is 0.1% by mass or less. By setting the content of 2-ethoxyethanol to 0.1% by mass or less, the adhesive heat resistance of the 2-cyanoacrylate-based adhesive composition can be improved.

[0020] 2-Ethoxyethanol is a solvent widely used in commercial and industrial applications and is a compound contained as a manufacturing impurity in ethoxyethyl-2-cyanoacrylate.

[0021] In the 2-cyanoacrylate adhesive composition of the present disclosure, the content of 2-ethoxyethanol is preferably 0.1% by mass or less, more preferably 0.07% by mass or less, still more preferably 0.06% by mass or less, and particularly preferably 0.05% by mass or less from the viewpoint of improving adhesion heat resistance.

[0022] The method for reducing the content of 2-ethoxyethanol in the 2-cyanoacrylate adhesive composition of the present disclosure is not particularly limited. For example, in the case of distillation, the distillation method includes heating a 2-cyanoacrylate compound containing more than a predetermined amount of 2-ethoxyethanol using a packed distillation column, a tray distillation column, or a rectification column. When purifying using a distillation column, for example, the theoretical number of stages of the distillation column is preferably 3 or more. Also, after producing ethoxyethyl-2-cyanoacrylate in a kettle, thoroughly cleaning the kettle with an alkaline cleaning agent or the like before producing ethoxyethyl-2-cyanoacrylate or another 2-cyanoacrylate, and not reusing the solvent used during production can also suppress the mixing of 2-ethoxyethanol from the previous batch to the next batch and reduce the content of 2-ethoxyethanol.

[0023] The content of 2-ethoxyethanol in the 2-cyanoacrylate adhesive composition of the present disclosure can be measured by gas chromatography.

[0024] 3. Other components The 2-cyanoacrylate adhesive composition of this disclosure may contain anionic polymerization inhibitors such as sulfur dioxide, p-toluenesulfonic acid, methanesulfonic acid, propanesalton, and boron trifluoride complexes, or radical polymerization inhibitors such as hydroquinone, catechol, and pyrogallol, in order to improve storage stability. Furthermore, curing accelerators such as polyethylene glycol derivatives, crown ethers, and calixalene may be added to improve the bonding speed. In addition, depending on the purpose, thickeners, plasticizers, fillers, elastomers, thixotropes, adhesion promoters, crosslinking agents, dyes, fragrances, etc., may be added. The amount of these additives can be appropriately selected within a range that does not impair the effect of improving adhesive heat resistance by reducing 2-ethoxyethanol and the practicality or economic efficiency of the adhesive of this disclosure. The 2-cyanoacrylate-based compositions of this disclosure make it possible to improve the adhesive heat resistance of the composition itself without adding additives that improve adhesive heat resistance, such as carboxylic acids, tannins, sulfur-containing compounds, quinoid compounds, and NBR polymers. Furthermore, the compositions of this disclosure may be further improved by adding the aforementioned additives that improve adhesive heat resistance.

[0025] 4. Joined product and its manufacturing method The 2-cyanoacrylate adhesive composition of this disclosure has excellent heat resistance for bonding to metals, and is therefore suitable for use as an adhesive for bonding two parts, at least one of which is made of metal, in a manufacturing method for bonding two parts. Accordingly, according to this disclosure, a bonded product can be manufactured comprising at least a first metal part and a second part bonded thereto, wherein the first part and the second part are bonded together via the 2-cyanoacrylate adhesive composition of this disclosure. In this case, the 2-cyanoacrylate adhesive composition of this disclosure may be bonded directly to the metal surface of the first part, or it may be bonded to a metal surface that has been pre-primed. Aluminum is preferred as the metal constituting the first part. The material of the second part is not particularly limited and can be appropriately selected from metal, plastic, rubber, wood, concrete, etc.

[0026] Examples of the bonded products of this disclosure include laminates formed by overlapping and joining two sheet-like components, and laminates formed by covering and joining a linear component with other components. Examples include articles in which a metal component is attached to a resin molded product. More specifically, examples include printed circuit boards and their laminates, wire harnesses, connectors, insulated wires, etc. [Examples]

[0027] The present disclosure will be described in more detail below based on examples, but the disclosure is not limited thereto. In the following, parts and percentages are based on mass unless otherwise specified.

[0028] 1. Adhesion heat resistance test (1) Preparation of test specimens In accordance with JIS K 6861 "Test Method for α-Cyanoacrylate Adhesives," two substrates were bonded together using the obtained 2-cyanoacrylate adhesive composition under conditions of 23°C and 50% RH to prepare test specimens (AL / AL) for measuring tensile shear adhesive strength. • Base material: Aluminum test piece (material: A1050P, 3.0 x 25 x 50 mm) manufactured by Nippon Test Panel Co., Ltd., which was sandblasted and then degreased with ethanol. (2) Tensile shear test For the above test specimens, the tensile shear adhesive strength was measured initially, and after being placed in an oven set to 120°C for 3, 5, 10, or 15 days, and then removed and allowed to return to room temperature, in accordance with JIS K 6861 "Test Method for α-Cyanoacrylate Adhesives". • Oven: VT program temperature controller (manufactured by Isuzu Manufacturing Co., Ltd.) • Tensile shear testing apparatus: Autograph AGS-50kN Xplus (manufactured by Shimadzu Corporation) Test mode: Tensile shear Test speed: 10 mm / min

[0029] 2. Manufacturing of adhesive compositions (Example 1) A 2-cyanoacrylate adhesive composition according to Example 1 was obtained by blending 99.854 parts by mass of ethoxyethyl-2-cyanoacrylate with 0.064 parts by mass of 2-ethoxyethanol, and 0.002 parts by mass of BF3-diethyl ether complex and 0.080 parts by mass of hydroquinone as polymerization inhibitors, resulting in a 2-cyanoacrylate adhesive composition with a 2-ethoxyethanol content of 0.064% by mass. (Example 2) A 2-cyanoacrylate adhesive composition according to Example 2 was obtained by mixing ethoxyethyl-2-cyanoacrylate and ethyl-2-cyanoacrylate in a mass ratio of 8:2 in 99.957 parts by mass of a 2-cyanoacrylate mixture, adding 0.051 parts by mass of 2-ethoxyethanol, and 0.002 parts by mass of BF3-diethyl ether complex and 0.080 parts by mass of hydroquinone as polymerization inhibitors, resulting in a 2-cyanoacrylate adhesive composition with a 2-ethoxyethanol content of 0.051% by mass. (Example 3) A 2-cyanoacrylate adhesive composition according to Example 3 was obtained by mixing ethoxyethyl-2-cyanoacrylate and ethyl-2-cyanoacrylate in a mass ratio of 6:4 in 99.880 parts by mass of a 2-cyanoacrylate mixture, adding 0.038 parts by mass of 2-ethoxyethanol, and 0.002 parts by mass of BF3-diethyl ether complex and 0.080 parts by mass of hydroquinone as polymerization inhibitors, resulting in a 2-cyanoacrylate adhesive composition with a 2-ethoxyethanol content of 0.038% by mass. (Comparative Examples 1 and 2) Except for changing the amount of ethoxyethyl-2-cyanoacrylate to 99.418 parts by mass and 99.918 parts by mass, respectively, and changing the amount of 2-ethoxyethanol to 0.50 parts by mass and 1.0 part by mass, respectively, 2-cyanoacrylate-based adhesive compositions for Comparative Examples 1 and 2 were obtained in the same manner as in Example 1, with 2-ethoxyethanol content of 0.50% by mass and 1.0% by mass, respectively. (Comparative Examples 3 and 4) Except for changing the amounts of the 2-cyanoacrylate mixture to 99.418 parts by mass and 98.918 parts by mass, respectively, and changing the amounts of 2-ethoxyethanol to 0.50 parts by mass and 1.0 part by mass, respectively, 2-cyanoacrylate-based adhesive compositions for Comparative Examples 3 and 4 were obtained in the same manner as in Example 2, with 2-ethoxyethanol content of 0.50% by mass and 1.0% by mass, respectively. (Comparative Examples 5 and 6) Except for changing the amounts of the 2-cyanoacrylate mixture to 99.418 parts by mass and 99.498 parts by mass, respectively, and changing the amounts of 2-ethoxyethanol to 0.50 parts by mass and 1.0 part by mass, respectively, a 2-cyanoacrylate-based adhesive composition for Comparative Examples 5 and 6 was obtained in the same manner as in Example 3, with 2-ethoxyethanol content of 0.50% by mass and 1.0% by mass, respectively.

[0030] The 2-cyanoacrylate adhesive compositions obtained in Examples 1-3 and Comparative Examples 1-6 were used to perform the above-described adhesive heat resistance tests. The results are shown in Table 1.

[0031] [Table 1]

[0032] From the comparison between Example 1 and Comparative Examples 1 and 2, between Example 2 and Comparative Examples 3 and 4, and between Example 3 and Comparative Examples 5 and 6 in Table 1 above, it was found that the 2-cyanoacrylate adhesive composition in the example, in which the 2-ethoxyethanol content was within the range specified in this disclosure, did not experience a decrease in tensile shear adhesive strength even after being placed in a high-temperature environment of 120°C after bonding, and exhibited excellent adhesive heat resistance. In contrast, the 2-cyanoacrylate adhesive composition in the comparative example, in which the 2-ethoxyethanol content exceeded the range specified in this disclosure, tended to experience a decrease in tensile shear adhesive strength when placed in a high-temperature environment of 120°C after bonding, and exhibited poor adhesive heat resistance. [Industrial applicability]

[0033] The 2-cyanoacrylate adhesive composition obtained by this disclosure has improved heat resistance without impairing instantaneous adhesion due to the addition of additives, and is suitable for use as an instantaneous adhesive in applications requiring higher heat resistance in fields such as household and industrial use.

Claims

1. A 2-cyanoacrylate adhesive composition containing a 2-cyanoacrylate compound including ethoxyethyl-2-cyanoacrylate, wherein the content of 2-ethoxyethanol is 0.1% by mass or less.

2. The 2-cyanoacrylate adhesive composition according to claim 1, comprising 30% by mass or more of the ethoxyethyl-2-cyanoacrylate based on the total amount of the 2-cyanoacrylate compound.

3. The 2-cyanoacrylate adhesive composition according to claim 1, comprising an alkyl-2-cyanoacrylate having an alkyl group having 1 to 4 carbon atoms in the main chain.

4. A 2-cyanoacrylate adhesive composition according to claim 1, for use with aluminum.

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