2-Cyanoacrylate-based adhesive composition and thickener

Abstract

The present invention provides a 2-cyanoacrylate-based adhesive composition that can suppress excessive thickening over time and has good storage stability, as well as a suitable thickener for use in this 2-cyanoacrylate-based adhesive composition. [Solution] The 2-cyanoacrylate adhesive composition contains a 2-cyanoacrylate compound and a sulfide compound, with a sulfide compound content of 2.0 × 10 -8 The concentration is mol / g or less. The 2-cyanoacrylate adhesive composition may further contain a thickener. The sulfide compound may be derived from the thickener. The thickener for the 2-cyanoacrylate adhesive composition contains a sulfide compound, and the sulfide compound content is 8.0 × 10⁻⁶. -8 It is less than or equal to mol / g.

Description

[Technical Field]

[0001] This invention relates to a 2-cyanoacrylate adhesive composition and a thickening agent. [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 strong bonding of 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] In 2-cyanoacrylate adhesive compositions, the monomer 2-cyanoacrylate compound has extremely low viscosity. Therefore, the 2-cyanoacrylate compound penetrates porous materials such as wood and foam, as well as fibers, paper, and leather. For this reason, various thickeners, such as resins, are added to the 2-cyanoacrylate adhesive composition as needed to adjust the viscosity of the composition.

[0004] For example, Patent Document 1 describes using a methacrylic resin composition containing 90% by mass or more of a methacrylic resin having a specific structural formula in at least a portion of the monomer units constituting the polymer ends as a thickener for adhesives.

[0005] Furthermore, for example, Patent Document 2 discloses an α-cyanoacrylate-based adhesive composition comprising: (a) 100 parts by weight of α-cyanoacrylate; (b) 10 to 20 parts by weight of polyalkyl methacrylate or copolymer of alkyl methacrylate and other methacrylic acid esters or acrylic acid esters having a weight-average molecular weight of 10 to 300,000; (c) 2 to 20 parts by weight of ultrafine powdered anhydrous silica; and (d) 0 to 20 parts by weight of a rapid-curing additive. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2018-178076 [Patent Document 2] Japanese Patent Application Publication No. 8-53651 [Overview of the project] [Problems that the invention aims to solve]

[0007] Incidentally, 2-cyanoacrylate adhesive compositions may experience an excessive increase in viscosity (thickening) during storage compared to their initial viscosity when prepared as an adhesive composition. Excessive thickening during storage leads to a decrease in the storage stability of the adhesive composition.

[0008] The present invention has been made in view of the above problems, and aims to provide a 2-cyanoacrylate adhesive composition that can suppress excessive thickening over time and has good storage stability, as well as a thickening agent suitable for use in this 2-cyanoacrylate adhesive composition. [Means for solving the problem]

[0009] The 2-cyanoacrylate adhesive composition and thickener according to the present invention are as follows.

[0010] [1] It contains 2-cyanoacrylate compounds and sulfide compounds, The content of the aforementioned sulfide compound is 2.0 × 10 -8 It is mol / g or less. A 2-cyanoacrylate adhesive composition. [2] Furthermore, it contains a thickening agent. [1] The 2-cyanoacrylate adhesive composition described above. [3] The sulfide compound is derived from the thickener. [2] The 2-cyanoacrylate adhesive composition described above. [4] The thickener contains at least a (meth)acrylic resin. The 2-cyanoacrylate-based adhesive composition according to [2] or [3]. [5] The thickener contains at least one selected from the group consisting of polymethyl methacrylate, a copolymer of methyl methacrylate and an acrylate ester, a copolymer of methyl methacrylate and other methacrylate esters, and an acrylic rubber. The 2-cyanoacrylate-based adhesive composition according to any one of [2] to [4]. [6] The sulfide compound has at least one alkyl group having 1 to 25 carbon atoms. The 2-cyanoacrylate-based adhesive composition according to any one of [1] to [5]. [7] The 2-cyanoacrylate-based compound contains a 2-cyanoacrylate ester represented by the following general formula (1). The 2-cyanoacrylate-based adhesive composition according to any one of [1] to [6]. However, in the general formula (1), R is an alkyl group, an alkenyl group or an alkoxyalkyl group having 1 to 10 carbon atoms.

[0011]

Chemical formula

[0012] [8] The content of the thickener is 0.1 part by mass or more and 25 parts by mass or less with respect to 100 parts by mass of the 2-cyanoacrylate-based compound. The 2-cyanoacrylate-based adhesive composition according to any one of [2] to [7]. <00001​​​​​​​​​​Thickening agent. The thickening agent can be used in any one of the 2-cyanoacrylate adhesive compositions described in [1] to [8]. [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 suppress excessive thickening over time and can have good storage stability.

[0014] Furthermore, the thickener for the 2-cyanoacrylate adhesive composition described above has the above configuration. Therefore, even when the thickener for the 2-cyanoacrylate adhesive composition is incorporated into the 2-cyanoacrylate adhesive composition for thickening purposes, it can suppress excessive thickening of the 2-cyanoacrylate adhesive composition over time, thereby improving the storage stability of the 2-cyanoacrylate adhesive composition. [Modes for carrying out the invention]

[0015] 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).

[0016] 1. 2-Cyanoacrylate adhesive composition The 2-cyanoacrylate adhesive composition of this embodiment (hereinafter sometimes referred to as "this adhesive composition") contains a 2-cyanoacrylate compound and a sulfide compound. This adhesive composition will be described in detail below.

[0017] 1.1 2-Cyanoacrylate Compounds In this adhesive composition, 2-cyanoacrylate compounds are important adhesive components for exhibiting adhesive properties. This adhesive composition may contain only one type of 2-cyanoacrylate compound, or it may contain two or more types.

[0018] The 2-cyanoacrylate compound preferably includes a 2-cyanoacrylate ester represented by the following general formula (1), and more preferably a 2-cyanoacrylate ester represented by the following general formula (1).

[0019] [ka]

[0020] In general formula (1), R is an alkyl group, alkenyl group, or alkoxyalkyl group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms.

[0021] Specific examples of 2-cyanoacrylate esters represented by general formula (1) 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.

[0022] Of these, alkyl-2-cyanoacrylate is preferred from the viewpoint of instantaneous adhesion and adhesive strength, and methyl-2-cyanoacrylate, ethyl-2-cyanoacrylate, propyl-2-cyanoacrylate, and isopropyl-2-cyanoacrylate are more preferred.

[0023] In this adhesive composition, the content of the 2-cyanoacrylate compound is preferably 40% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more, from the viewpoint of curability, bonding speed, and bonding strength.

[0024] 1.2 Sulfide Compounds In this adhesive composition, sulfide compounds are impurities that should be restricted from the viewpoint of suppressing excessive thickening of the adhesive composition over time.

[0025] Sulfide compounds may have a structure in which two organic groups are bonded to one sulfur atom (a structure having a monosulfide bond), such as RS-R' (where R and R' are the same or different organic groups), or they may have a structure in which an organic group is bonded to one and the other of two sulfur atoms bonded to each other (a structure having a disulfide bond), such as RSS-R' (where R and R' are the same or different organic groups), and RS x The adhesive composition may have a structure in which organic groups are bonded to one end and the other end of x sulfur atoms that are bonded to each other, such as -R' (where R and R' are the same or different organic groups, x>2) (a structure having a polysulfide bond, for example, a structure having a trisulfide bond when x=3). Monosulfide bonds, disulfide bonds, and polysulfide bonds are collectively called sulfide bonds. This adhesive composition may contain only one sulfide compound or two or more.

[0026] This adhesive composition contains a sulfide compound with a content of 2.0 × 10 -8It is 2.0 × 10 -8 mol / g or less. In this adhesive composition, the content of the sulfide compound means the molar amount of the sulfide compound with respect to the mass of the 2-cyanoacrylate compound. In the adhesive composition containing the sulfide compound as an impurity, by regulating the content of the sulfide compound to 2.0 × 10

[0027] mol / g or less, excessive thickening over time can be suppressed, and the storage stability can be made good.

[0028] From the viewpoint of improving the effect of suppressing excessive thickening over time and the like, the content of the sulfide compound is preferably 1.8 × 10 -8 mol / g or less, more preferably 1.5 × 10 -8 [[ID=I4]]mol / g or less, still more preferably 1.0 × 10 -8 mol / g or less, even more preferably 0.3 × 10 -8 mol / g or less, even more preferably 0.1 × 10 -8 mol / g or less, and most preferably 0.1 × 10

[0029] The content of sulfide compounds can be measured using gas chromatography-time-of-flight mass spectrometry (GC / TOF-MS) or pyrolysis gas chromatography-mass spectrometry (pyrolysis GC / MS). Specifically, low molecular weight sulfide compounds can be measured by GC / TOF-MS after diluting the adhesive composition with a suitable solvent selected from alcoholic solvents, hydrocarbon solvents, acetone, ethyl acetate, dichloromethane, acetonitrile, carbon disulfide, tetrahydrofuran, and chloroform. Sulfide compounds attached to polymer ends, etc., can be measured by pyrolysis GC / MS. Measurement by pyrolysis GC / MS can be performed as follows: The adhesive composition is decomposed at a suitable pyrolysis temperature set within the range of 300°C to 600°C to obtain low molecular weight sulfide compounds, and these compounds are used as standards to create a calibration curve. Assuming 100% decomposition by pyrolysis GC / MS, this can be quantified from the calibration curve.

[0030] Examples of sulfide compounds include sulfide compounds having at least one alkyl group with 1 to 25 carbon atoms. Specifically, examples of sulfide compounds having at least one alkyl group with 1 to 25 carbon atoms include those having an alkyl group with 1 to 25 carbon atoms as one of the organic groups of the sulfide bond. In this case, the other organic group of the sulfide bond is not particularly limited, but examples include polymers containing constituent units derived from (meth)acrylate, such as polymers of (meth)acrylate. Examples of (meth)acrylate include alkyl (meth)acrylate. Note that (meth)acrylate means methacrylate and / or acrylate.

[0031] In this adhesive composition, the sulfide compound may originate from a thickener described later, from the viewpoint that it can efficiently thicken using a thickener with a narrow molecular weight distribution. The reason why sulfide compounds may be present in thickeners is not clear, but it is presumed that they are introduced due to some factor during the manufacturing or purification process of the thickener. When such a thickener is incorporated into this adhesive composition, the sulfide compound contained in this adhesive composition will originate from the thickener. Here, an example has been given of the case where the sulfide compound originates from the thickener, but in this adhesive composition, the sulfide compound may also originate from other additives other than thickeners.

[0032] 1.3 Thickening agents In addition to 2-cyanoacrylate compounds and sulfide compounds, this adhesive composition may also contain a thickening agent. The thickening agent is an additive that, when added to this adhesive composition, can increase the viscosity of the composition. By further containing a thickening agent, this adhesive composition can improve adhesion to substrates that are easily penetrated by 2-cyanoacrylate compounds, such as wood, porous materials like foam, fibers, paper, and leather.

[0033] As a thickening agent, it may contain, for example, at least (meth)acrylic resin, from the viewpoint of good compatibility with 2-cyanoacrylate compounds, uniform mixing, and maintaining transparency. The (meth)acrylic resin constituting the thickening agent may be of one type only, or two or more types may be used in combination. Note that (meth)acrylic resin means methacrylic resin and / or acrylic resin. Furthermore, the thickening agent may be of one type only, or two or more types may be used in combination.

[0034] Examples of thickening agents include polymethyl methacrylate, copolymers of methyl methacrylate and acrylic acid esters, copolymers of methyl methacrylate and other methacrylic acid esters, and acrylic rubber. These may be used individually or in combination of two or more.

[0035] Examples of acrylic acid esters used in copolymers of methyl methacrylate and acrylic acid esters include methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, n-hexyl acrylate, n-heptyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, methoxyethyl acrylate, methoxypropyl acrylate, ethoxyethyl acrylate, and ethoxypropyl acrylate. These may be used individually or in combination of two or more.

[0036] In copolymers of methyl methacrylate and other methacrylate esters, the other methacrylate esters are methacrylate esters other than methyl methacrylate, specifically including ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, n-hexyl methacrylate, n-heptyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, methoxyethyl methacrylate, methoxypropyl methacrylate, ethoxyethyl methacrylate, and ethoxypropyl methacrylate. These may be used individually or in combination of two or more.

[0037] In this adhesive composition, the content of the thickening agent is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of the 2-cyanoacrylate compound, from the viewpoint of ensuring a reliable thickening effect. On the other hand, the content of the thickening agent is preferably 25 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less, per 100 parts by mass of the 2-cyanoacrylate compound, from the viewpoint of instantaneous adhesion and adhesive strength.

[0038] 1.4 Other ingredients In addition to 2-cyanoacrylate compounds and sulfide compounds, this adhesive composition may contain thickeners as described above. Furthermore, it may also contain, as necessary, various additives conventionally used in 2-cyanoacrylate adhesive compositions.

[0039] Examples of the above-mentioned additives include stabilizers, plasticizers, anionic polymerization accelerators, fillers (such as silica particles), colorants, fragrances, solvents, and strength enhancers. These may be used individually or in combination of two or more.

[0040] Examples of stabilizers include 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, HBF4, and anionic polymerization inhibitors such as trialkylborates; and 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.

[0041] 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, and 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.

[0042] The plasticizer content is preferably 0.0001 parts by mass or more and 20 parts by mass or less, more preferably 0.001 parts by mass or more and 10 parts by mass or less, and even more preferably 0.01 parts by mass or more and 7 parts by mass or less, per 100 parts by mass of the 2-cyanoacrylate compound.

[0043] Examples of anionic polymerization accelerators include polyalkylene oxides, crown ethers, silacrown ethers, calixalenes, cyclodextrins, and pyrogallol-based cyclic compounds. These may be used individually or in combination of two or more.

[0044] 1.5 Application This adhesive composition can be suitably used, for example, as a so-called instant adhesive. Because this adhesive composition can suppress excessive thickening over time and has good storage stability, it can be used in a wide range of fields, including industrial, medical, and household applications.

[0045] Furthermore, this adhesive composition can be suitably used on various substrates made of metal, resin, rubber, wood, ceramics, and the like.

[0046] 1.6 Manufacture of this adhesive composition This adhesive composition contains 2.0 × 10⁻⁶ sulfide compounds in a 2-cyanoacrylate adhesive composition. -8 Although it is also possible to produce it by adding a sulfide compound to a 2-cyanoacrylate compound so that the concentration is mol / g or less, the following production method is preferred.

[0047] In other words, this adhesive composition, for example, has a sulfide compound content of 2.0 × 10 in a 2-cyanoacrylate-based adhesive composition. -8 It is preferable to manufacture the adhesive by blending and preparing various additives, such as thickeners containing sulfide compounds, so that the sulfide compound content is 2.0 × 10⁻⁶ or less. As mentioned above, although this adhesive composition contains sulfide compounds, this manufacturing method does not require the active addition of sulfide compounds themselves, which should be regulated as impurities, and the sulfide compound content in the 2-cyanoacrylate adhesive composition is 2.0 × 10⁻⁶. -8 This offers the advantage of being able to control the quality of the adhesive composition by managing the amount of sulfide compounds contained in the additives so that it does not exceed mol / g.

[0048] 2. Thickener for 2-cyanoacrylate adhesive compositions The thickener for the 2-cyanoacrylate adhesive composition of this embodiment (hereinafter sometimes referred to as "this thickener") contains a sulfide compound.

[0049] In this thickening agent, the sulfide compound content is 8.0 × 10 -8The amount is specified as mol / g or less. In this thickener, the sulfide compound content refers to the amount of moles of the sulfide compound relative to the mass of the thickener. This allows for the preparation of an adhesive composition in which a predetermined amount of the thickener is added to suppress excessive thickening over time.

[0050] Furthermore, when this adhesive composition contains a thickener, the less sulfide compound it contains, the better, from the viewpoint of suppressing excessive thickening over time. Therefore, there is no particular lower limit to the sulfide compound content in this thickener. However, as mentioned above, since this thickener is based on the premise that it contains a sulfide compound, the sulfide compound content is greater than 0 mol / g.

[0051] The sulfide compound content in this thickener is set at 8.0 × 10⁻⁶ to ensure the suppression of excessive thickening over time in this adhesive composition. -8 It is preferable that the amount is mol / g or less, and 6.0 × 10 -8 It is more preferable that the value be mol / g or less, and 4.0 × 10 -8 It is even more preferable that the concentration be mol / g or less.

[0052] The sulfide compound content in this thickener can be measured using gas chromatography-time-of-flight mass spectrometry (GC / TOF-MS) or pyrolysis gas chromatography-mass spectrometry (pyrolysis GC / MS), in the same manner as the sulfide compound content in the adhesive composition described above. Specifically, low molecular weight sulfide compounds can be measured by GC / TOF-MS after dissolving the thickener in a suitable solvent selected from alcoholic solvents, hydrocarbon solvents, acetone, ethyl acetate, dichloromethane, acetonitrile, carbon disulfide, tetrahydrofuran, and chloroform. Sulfide compounds attached to polymer ends, etc., can be measured by pyrolysis GC / MS. Measurement by pyrolysis GC / MS can be performed as follows: The thickener is decomposed at a suitable pyrolysis temperature set within the range of 300°C to 600°C to obtain low molecular weight sulfide compounds, and a calibration curve is drawn using these compounds as standards. Assuming 100% decomposition by pyrolysis GC / MS, this can be quantified from the calibration curve.

[0053] For details regarding the sulfide compounds in this thickener, please refer to the description of sulfide compounds in "1. 2-Cyanoacrylate-based Adhesive Compositions" above, and a detailed explanation is omitted here.

[0054] Furthermore, the descriptions above for "1. 2-Cyanoacrylate-based adhesive compositions" and "2. Thickeners for 2-Cyanoacrylate-based adhesive compositions" can be referenced from each other as needed, and the components described in each description can be applied individually or in any combination as necessary. [Examples]

[0055] The present invention will be described more specifically based on examples, but the present invention is not limited thereto. In the following, parts, %, and ppm are based on mass unless otherwise specified.

[0056] <Preparation of 2-cyanoacrylate adhesive compositions> (Sample 1) 10 parts by mass of tributyl acetylcitrate (hereinafter sometimes referred to as ATBC) were mixed with 0.1 parts by mass of dodecyl methyl sulfide and stirred until homogeneous. The resulting ATBC solution contained 0.005 × 10⁶ dodecyl methyl sulfide in the composition. -8 The 2-cyanoacrylate was added to ethyl-2-cyanoacrylate to a concentration of mol / g, and the mixture was stirred until homogeneous. This prepared the 2-cyanoacrylate adhesive composition of Sample 1.

[0057] (Samples 2-3, Sample 1C) Following the procedure for Sample 1, an ATBC solution of dodecylmethyl sulfide was prepared so that the amount of sulfide compound to be incorporated into the 2-cyanoacrylate adhesive composition was the predetermined amount shown in Tables 1 and 2. This solution was then added to ethyl-2-cyanoacrylate and stirred. This resulted in the preparation of the 2-cyanoacrylate adhesive compositions of Samples 2-3 and Sample 1C.

[0058] (Sample 4) 10 parts by mass of tributyl acetyl citrate (ATBC) were mixed with 0.2 parts by mass of 2-(methylthio)ethanol and stirred until homogeneous. The resulting ATBC solution contained 0.3 × 10⁶ parts of 2-(methylthio)ethanol. -8 The 2-cyanoacrylate was added to ethyl-2-cyanoacrylate to a concentration of mol / g, and the mixture was stirred until homogeneous. This prepared the 2-cyanoacrylate adhesive composition of sample 4.

[0059] (Samples 5-10, Sample 2C) Following the procedure for Sample 4, an ATBC solution of 2-(methylthio)ethanol was prepared so that the amount of sulfide compound to be incorporated into the 2-cyanoacrylate adhesive composition was the predetermined amount shown in Tables 1 and 2. This solution was then added to ethyl-2-cyanoacrylate and stirred. This resulted in the preparation of the 2-cyanoacrylate adhesive compositions of Samples 5 to 10 and Sample 2C.

[0060] (Sample 11) Ethyl-2-cyanoacrylate was mixed with a thickening agent and stirred overnight at 60°C to dissolve and obtain a thickened solution of ethyl-2-cyanoacrylate. Next, 0.2 parts by mass of 2-(methylthio)ethanol was added to 10 parts by mass of tributyl acetyl citrate (ATBC) and stirred until homogeneous. The resulting ATBC solution contained 1.1 × 10⁶ units of 2-(methylthio)ethanol in the composition. -8 The 2-cyanoacrylate adhesive composition of sample 11 was prepared by adding it to a thickening solution of ethyl-2-cyanoacrylate to a concentration of mol / g and stirring until homogeneous.

[0061] (Sample 1R) The ethyl-2-cyanoacrylate itself, which does not contain sulfide compounds, used in the 2-cyanoacrylate adhesive composition of Sample 1, was used as the 2-cyanoacrylate adhesive composition of Sample 1R. Sample 1R is a reference example of a 2-cyanoacrylate adhesive composition that does not contain sulfide compounds.

[0062] <Content of sulfide compounds> The sulfide compound content of each 2-cyanoacrylate adhesive composition prepared was measured according to the measurement method described above, and the results are shown in Tables 1 and 2.

[0063] <Viscosity> The viscosity of each prepared 2-cyanoacrylate adhesive composition was measured at 25°C using an E-type viscometer (cone-plate viscometer). In this experiment, the viscosity of the 2-cyanoacrylate adhesive composition immediately after preparation was defined as the initial viscosity. The prepared 2-cyanoacrylate adhesive composition was then stored at 80°C for 14 days, and its viscosity was measured at 25°C afterward. This was defined as the viscosity after 80°C × 14 days. The above storage was performed by sealing 3.0g of the 2-cyanoacrylate adhesive composition in a 4g aluminum container. The viscosity change rate was calculated using the formula: (viscosity after 80°C × 14 days) / initial viscosity.

[0064] <Storage stability> When the viscosity change rate was 35 times or less, it was determined that excessive thickening over time could be suppressed, and good storage stability could be ensured. In Tables 1 and 2, cases where the viscosity change rate was 2.5 times or less were indicated as "A", cases where it was between 2.5 times and 10 times were indicated as "B", and cases where it was between 10 times and 35 times were indicated as "C". Furthermore, when the viscosity change rate exceeded 35 times, excessive thickening over time occurred, resulting in poor storage stability, and this was indicated as "D" in Tables 1 and 2.

[0065] The detailed composition, various measurement results, and evaluation results for each 2-cyanoacrylate adhesive composition are summarized in Tables 1 and 2.

[0066] [Table 1]

[0067] [Table 2]

[0068] Tables 1 and 2 show the following: Sample 1C has a sulfide compound (dodecylmethyl sulfide) content of 2.0 × 10⁻⁶ in its 2-cyanoacrylate adhesive composition. -8 The concentration was greater than mol / g. As a result, sample 1C underwent excessive thickening over time, resulting in poor storage stability.

[0069] Sample 2C has a sulfide compound (2-(methylthio)ethanol) content of 2.0 × 10⁻¹⁰ in its 2-cyanoacrylate adhesive composition. -8 The concentration was greater than mol / g. Therefore, like sample 1C, sample 2C underwent excessive thickening over time, resulting in poor storage stability.

[0070] In contrast, samples 1 to 11 have a sulfide compound content of 2.0 × 10 in their 2-cyanoacrylate adhesive compositions. -8The limit is mol / g or less. Therefore, samples 1 to 11 were able to suppress excessive thickening over time and ensure good storage stability.

[0071] In this example, in order to investigate the effect of sulfide compounds on the viscosity change of 2-cyanoacrylate adhesive compositions, a sulfide compound was dissolved in tributyl acetylcitrate and intentionally added to the 2-cyanoacrylate compound to prepare a 2-cyanoacrylate adhesive composition. This does not mean that it is essential to add the sulfide compound itself in the actual production of 2-cyanoacrylate adhesive compositions. As mentioned above, the sulfide compound may originate from various additives added to the 2-cyanoacrylate adhesive composition, such as a thickener. In other words, a 2-cyanoacrylate adhesive composition containing both a 2-cyanoacrylate compound and a sulfide compound may be prepared by adding an additive such as a thickener containing a sulfide compound to the 2-cyanoacrylate compound.

[0072] 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. It contains 2-cyanoacrylate compounds and sulfide compounds, The content of the aforementioned sulfide compound is 2.0 × 10 －８ It is less than or equal to mol / g. A 2-cyanoacrylate adhesive composition.

2. Furthermore, it contains a thickening agent. The 2-cyanoacrylate adhesive composition according to claim 1.

3. The sulfide compound is derived from the thickener. The 2-cyanoacrylate adhesive composition according to claim 2.

4. The aforementioned thickener comprises at least a (meth)acrylic resin. The 2-cyanoacrylate adhesive composition according to claim 2.

5. The thickening agent comprises at least one selected from the group consisting of polymethyl methacrylate, a copolymer of methyl methacrylate and an acrylic acid ester, a copolymer of methyl methacrylate and another methacrylic acid ester, and acrylic rubber. The 2-cyanoacrylate adhesive composition according to claim 2.

6. The sulfide compound has at least one alkyl group having 1 to 25 carbon atoms. The 2-cyanoacrylate adhesive composition according to claim 1.

7. The aforementioned 2-cyanoacrylate compound includes a 2-cyanoacrylate ester represented by the following general formula (1): The 2-cyanoacrylate adhesive composition according to claim 1. 【Chemistry 1】 (However, in general formula (1), R is an alkyl group, alkenyl group, or alkoxyalkyl group having 1 to 10 carbon atoms.)

8. The content of the thickening agent is 0.1 parts by mass or more and 25 parts by mass or less per 100 parts by mass of the 2-cyanoacrylate compound. The 2-cyanoacrylate adhesive composition according to claim 2.

9. A thickening agent for 2-cyanoacrylate adhesive compositions, It contains sulfide compounds, The content of the aforementioned sulfide compound is 8.0 × 10 －８ It is less than or equal to mol / g. Thickening agent.

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