JPH10176142A - Cyanoacrylate adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive having excellent instant adhesiveness by using an alkoxyalkyl 2-cyanoacrylate or tetrahydrofurfuryl 2cyanoacrylate as the principal component, using BF3 or a BF3 complex salt as the anionic polymerization inhibitor and specifying the acid component content. SOLUTION: An alkoxyalkyl 2-cyanoacrylate or tetrahydrofurfuryl 2- cyanoacrylate is used as the principal component of a cyanoacrylate adhesive. This compound is mixed with 50-100ppm of an anionic polymerization inhibitor being BF3 or a BF3 complex salt such as a BF3/ether complex salt, a cure accelerator being 0.001-1wt.% compound selected among crown ethers and their analogues or 0.01-10wt.% compound selected among polyalkylene oxides of a molecular weight of 100-10,000 and their derivatives and 5-40wt.% flexibilizer to obtain an adhesive composition having an acid component content of 0.5×10<-6> g equivalent/g.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cyanoacrylate-based adhesive composition having the characteristics that no whitening phenomenon is observed and no irritating odor, and also has excellent storage stability and instant adhesiveness. In addition, the present invention belongs to various technologies using an adhesive, particularly to an adhesive manufacturing technology.

[0002]

2. Description of the Related Art A cyanoacrylate-based adhesive containing 2-cyanoacrylate as a main component is easily anionically polymerized and rapidly cured due to the presence of a small amount of water or a basic substance. It has been widely used in various industries, medical fields, leisure fields, and even general households as an instant adhesive. However, generally commercially available cyanoacrylate-based adhesives have the convenient property of instantaneously bonding glass, metal, plastic, wood, textile, paper, etc., but generally have the following various properties. There are potential drawbacks. <Defect 1> Due to a pungent odor, in a bonding operation using a large amount of an adhesive, if ventilation is poor, the user may feel discomfort. <Defect 2> Volatilized 2-cyanoacrylate polymerizes with atmospheric moisture and becomes a white powder and adheres to the periphery of the adherend of the adherend (whitening phenomenon), impairing the appearance of the adherend or producing electricity. -When applied to the bonding of electronic components, the adhesion of white powder to the contact portion may cause a contact failure. <Defect 3> Since the cured product is hard, the bending of the adherend may be hindered when the adherend is flexible.

Various proposals have been made in the past to solve these drawbacks. To improve the pungent odor and the whitening phenomenon, methoxyethyl 2-cyanoacrylate and ethoxyethyl 2-cyanoacrylate were used as 2-cyanoacrylates as raw materials. It has been proposed to use alkoxyalkyl 2-cyanoacrylates, etc., and tetrahydrofurfuryl 2-cyanoacrylates. For example, a method of using an alkylalkyl 2-cyanoacrylate in combination with an alkoxyalkyl 2-cyanoacrylate (Japanese Patent Publication No. 1-24190), a method of using a trichlorotrifluoroethane with an alkoxyalkyl2-cyanoacrylate or tetrahydrofurfuryl 2-cyanoacrylate ( Tokiko Sho 62-4746
2) water in an alkoxyalkyl 2-cyanoacrylate or tetrahydrofurfuryl 2-cyanoacrylate,
A method in which a radical polymerization inhibitor and an anion polymerization inhibitor are used in combination (Japanese Patent Publication No. 58-53676), a cyanoacetate content of 5% by weight or less, an alcohol content of 5% by weight or less, and a water content of 0.02 to 0.2% by weight Alkoxyalkyl 2-cyanoacrylate or tetrahydrofurfuryl
A method in which an anionic polymerization inhibitor is used in combination with 2-cyanoacrylate (Japanese Unexamined Patent Publication (Kokai) No. 55-151074), wherein an alkoxy having 2-alkoxyethyl cyanoacetate content of 0 to 5% by weight and 2-alkoxyethanol content of 0 to 5% by weight is used. A method in which an alkyl 2-cyanoacrylate is used in combination with a radical polymerization inhibitor and an anion polymerization inhibitor (JP-A-54-1979)
97636) and the like, and some cyanoacrylate-based adhesives with reduced pungent odor and whitening phenomenon have been put on the market. However, alkoxyalkyl
2-cyanoacrylate or tetrahydrofurfuryl 2-
A cyanoacrylate-based adhesive containing cyanoacrylate as a component does not have good storage stability compared to other or general-purpose cyanoacrylate-based adhesives containing 2-cyanoacrylate as a component.

On the other hand, as a method for improving the stability of the cyanoacrylate adhesive composition, various stabilizers and polymerization inhibitors have been proposed, among which boron trifluoride and boron trifluoride complex salt (hereinafter referred to as boron trifluoride complex salt). A method using a compound selected from BF ₃ and BF ₃ complex salt, an acidic gas other than BF ₃ and a specific compound (JP-A-62-1005).
68), a method using borofluoric acid (JP-A-3-7
786) have been proposed, but these methods are not necessarily effective for a cyanoacrylate-based adhesive containing an alkoxyalkyl 2-cyanoacrylate as a component. Accordingly, cyanoacrylate-based adhesives containing an alkoxyalkyl 2-cyanoacrylate are expected to improve the irritating odor and whitening phenomenon, but have a lower storage stability than general-purpose instant adhesives. Was remarkably limited, and the use had to remain for industrial use.

Further, as a method for imparting flexibility to a cyanoacrylate-based adhesive, a plasticizer (JP-A-2-34) is also used.
678), polymers (JP-A-2-34678, JP-A-5-346).
247409) or a polyfunctional compound (JP-A-6-1456)
05, JP-A-6-145606) and the like, a method of adding a softening agent has been proposed. In order to simultaneously solve the pungent odor, the whitening phenomenon, and the flexibility, it is conceivable to combine the above-described techniques into a cyanoacrylate-based adhesive,
As described above, a cyanoacrylate-based adhesive containing an alkoxyalkyl 2-cyanoacrylate as a component is not itself excellent in storage stability, and an adhesive obtained by adding a compound such as the above has storage stability. In addition to the worsening, the fact that the bonding speed is slightly slower is added, and the users and sales methods of the adhesive are further limited than those described above, and the use has to be limited to industrial use.

[0006]

The cyanoacrylate adhesive is used not only for industrial purposes but also for general consumers as an instant adhesive, and is an instant adhesive having no irritating odor and whitening phenomenon. Is an instant adhesive whose cured product is flexible, which is expected not only for industrial use but also for general consumers, and further improvement in storage stability and bonding speed is required in the industrial industry. is there. The present inventors have solved a problem of conventional 2-cyanoacrylate, irritating odor and whitening phenomenon, and have excellent properties of storage stability and adhesion speed. The research was conducted with the object of providing a cyanoacrylate-based instant adhesive having a flexible material.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that an alkoxyalkyl 2-cyanoacrylate or tetrahydrofurfuryl 2-cyano compound containing a specific anionic polymerization inhibitor is blended. A cyanoacrylate-based adhesive composition comprising acrylate and having a low acid content is a composition that solves the problem of pungent odor and whitening, and has excellent storage stability and instant adhesive properties. I found it. Further, they have found that the cured product becomes a flexible cyanoacrylate-based adhesive by further blending a softening agent, thereby completing the present invention.

That is, the present invention relates to a method comprising the steps of the following: comprising an alkoxyalkyl 2-cyanoacrylate or tetrahydrofurfuryl 2-cyanoacrylate as a main component and boron trifluoride or a boron trifluoride complex salt as an anionic polymerization inhibitor. A cyanoacrylate adhesive composition characterized by having an acid content of 0.5 × 10 ⁻⁶ gram equivalent number / g or less. [Method of measuring acid content] A sample obtained by mixing 3 g of the adhesive composition with 90 ml of acetone and further adding 3 ml of distilled water was used to obtain a sample having a pH of 4.5 to 5.5.
Neutralization titration is carried out with a 1 / 100N aqueous NaOH solution using an indicator having a discoloration range of 0. Further, the present invention provides a cyanoacrylate-based adhesive composition characterized in that a curing accelerator is used in combination with the composition, and a cyanoacrylate-based adhesive composition characterized in that a softening agent is used in combination. It is about.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The adhesive composition of the present invention will be described below. Specific examples of the alkoxyalkyl 2-cyanoacrylate which is a component of the composition used in the present invention include the following. That is, methoxyethyl, ethoxyethyl, propoxyethyl, isopropoxyethyl, butoxyethyl, hexyloxyethyl, 2-ethylhexyloxyethyl, butoxyethoxyethyl, hexyloxyethoxyethyl, 2-ethylhexyl as an ester of 2-cyanoacrylic acid. Siloxyethoxyethyl,
Esters such as, but not limited to, methoxypropyl, methoxypropoxypropyl, methoxypropoxypropoxypropyl, ethoxypropyl, and ethoxypropoxypropyl. Preferred alkoxyalkyl 2-cyanoacrylates used in the present invention are methoxyethyl 2-cyanoacrylate and ethoxyethyl 2-cyanoacrylate.

The following are specific examples of the boron trifluoride complex salt which is an anionic polymerization inhibitor used in the present invention. That is, complex salts of water, acetic acid, dimethyl ether, diethyl ether, dibutyl ether, t-butyl methyl ether, methanol, ethanol, propanol, isopropanol, phenol, methyl sulfide, and the like with boron trifluoride, but are not limited thereto. They can be used as a mixture. Among the boron trifluoride complex salts as anionic polymerization inhibitors used in the present invention, those preferred for the present invention are boron trifluoride alcohol complex salts and boron trifluoride ether complex salts. In the present invention, the compounding amount of the anionic polymerization inhibitor is 50 to 100 with respect to the adhesive composition.
When the amount of the anionic polymerization inhibitor is less than 50 ppm, the viscosity tends to deteriorate. On the other hand, when the amount exceeds 100 ppm, the adhesive speed tends to deteriorate, so that sufficient storage stability cannot be obtained.

[0011] The curing accelerator used in the present invention includes:
Crown ethers and their analogs (hereinafter referred to as "crown compounds") and polyalkylene oxides and derivatives thereof (hereinafter referred to as "alkylene oxide derivatives") are preferred, and one or more selected from those compounds are used. . The curing accelerator will be described in detail below. Crown compound The oxygen atom of crown ether has the property of being arranged inside the ring and taking in a metal ion or an organic ion at the center or above and below it by coordination bonds. The most typical crown ether is 18-crown-6 (a cyclic hexamer of ethylene oxide). Here, 18 indicates the number of rings, and 6
Indicates the number of oxygen. Representative crown ether compounds and their structures are reviewed in Chemical Review (James J
Christensen, Delbert J Eatough, Reed M Izatt, Cemi
cal Reviews 1974, Vol. 74, No. 3, 351-384). In the present invention, all of these compounds can be used, and in addition to these, compounds having a macrocyclic polyether structure and a so-called broad crown compound having a structure capable of selectively taking in metal ions and organic ions can be used. If available, it can be used. Further, compounds obtained by partially or completely substituting the oxygen of crown ethers with nitrogen, sulfur, phosphorus, boron or the like, such as dithia-15-crown, can also be used as the crown compound of the present invention. In addition, the portion of the ethylene group of the crown ether is not necessarily limited to only the ethylene group. , A part thereof may be substituted by a trimethylene group, a tetramethylene group, a pentamethylene group, or a part of the hydrogen of the ethylene group may be a methyl group, an ethyl group, a propyl group, a butyl group, an acetyl group, a phenyl group. It may be an analog substituted by a group, an oxygen group or a fluoro group. For example, Japanese Unexamined Patent Publication
All crown ethers and silacrown compounds disclosed in JP-A-331422 as anionic polymerization accelerators can be used as the curing accelerator of the present invention.

Alkylene Oxide Derivative In the present invention, various polyalkylene oxides and derivatives thereof can be used without any particular limitation. For example, the polyalkylene oxides and derivatives thereof disclosed in JP-B-60-26513, JP-B-1-43790, JP-A-63-128088, and JP-A-3-167279 can all be used. is there. Specific examples thereof include the following. [Polyalkylene oxide] diethylene glycol,
Triethylene glycol, tetraethylene glycol,
Polyethylene glycol, polypropylene glycol,
Poly 1,3-propylene glycol, polytrimethylene oxide, polytetramethylene oxide, polyepichlorohydrin, poly 3,3-bis (chloromethyl) butylene oxide, polytetramethylene ether glycol, poly 1,3-
Dioxolan, poly 2,2-bis (chloromethyl) propylene oxide, ethylene oxide-propylene oxide block polymer, diglycerin, triglycerin,
Polyglycerin such as tetraglycerin, formaldehyde condensate, acetaldehyde condensate, trioxane polymer and the like. Further, various polyalkylene oxides which are commercially available as polyether type urethane curing polyols can also be used as the curing accelerator of the present invention. [Polyalkylene oxide derivative] Representative examples of the polyalkylene oxide derivative include esters of the above-mentioned polyalkylene oxide and acid, ethers of the above-mentioned polyalkylene oxide and a hydroxy group-containing compound, and they are preferably used. In addition, Japanese Unexamined Patent Publication No.
The compounds disclosed in 248886, for example, polyalkylene oxide derivatives such as reaction products of isocyanatoethyl methacrylate and polyethylene glycol are also suitably used as the curing accelerator of the present invention.
Furthermore, without limitation, those having a polyalkylene oxide structure inside the molecule, such as those having various substituents at the molecular terminal, those having other bonding portions inside the polyalkylene oxide, etc. It can be used as a curing accelerator of the invention. Acids that can constitute the ester include acetic acid, propionic acid, butyric acid, isobutyric acid, pivalic acid, pentanoic acid, n-hexanoic acid, 2-
Methylpentanoic acid, n-octanoic acid, n-decanoic acid, lauric acid, palmitic acid, stearic acid, oleic acid, cyclohexylcarboxylic acid, cyclopentylcarboxylic acid, cyclopropylcarboxylic acid, acrylic acid, methacrylic acid, maleic acid, Itaconic acid, naphthenic acid, benzoic acid, β-naphthylcarboxylic acid, p-toluenecarboxylic acid, furancarboxylic acid, p-chlorobenzoic acid, monochloroacetic acid, cyanoacetic acid, glycolic acid, lactic acid, phenyloxypropionic acid, succinic acid, Glutaric acid, adipic acid, sebacic acid, butanetetracarboxylic acid, aconitic acid, propane-1,2,3-tricarboxylic acid, citric acid,
Examples include orthophthalic acid, isophthalic acid, trimellitic acid, and pyromellitic acid. The following are specific examples of the ester as the polyalkylene oxide derivative. [1] polyethylene glycol monoalkyl ester,
Polyethylene glycol dialkyl ester, polypropylene glycol dialkyl ester and the like (for example, esters such as acetate, trifluoroacetate, laurate, stearate, oleate and methacrylate). [2] Of bisphenol A, hydrogenated bisphenol A, trimethylolpropane, glycerin, adipic acid, trimellitic acid, isocyanate compound, phosphoric acid, silicic acid,
Polyalkylene oxide adducts and the like (alkylenes include, for example, ethylene and propylene). [3] Polyoxyethylene sorbitan ester, tetraoleic acid-polyoxyethylene sorbite, (polyoxyalkylene) polysilalate, (polyoxyalkylene) polyphosphate and the like (alkylene is, for example, ethylene, propylene and the like). Further, as the hydroxy group-containing compound that can constitute the ether, methanol, ethanol, propanol,
Isobutanol, hexanol, cyclohexanol,
2-ethyloctanol, decanol, lauryl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, phenol, α-naphthol, β-naphthol, cresol, t-butylphenol, octylphenol, nonylphenol, p-chlorophenol, resole, bisphenol A, 2 -Chloroethanol, ethylene cyanohydrin, trifluoroethanol, benzyl alcohol, 1,4-butanediol, 1,6-hexanediol, glycerin, sorbitol, hydrogenated bisphenol A, trimethylolpropane and the like.
Specific examples of the ether as the polyalkylene oxide derivative include, for example, the following. [1] Diethylene glycol monoalkyl ether, diethylene glycol dialkyl ether, dipropylene glycol monoalkyl ether, dipropylene glycol dialkyl ether and the like (alkyl is, for example, methyl, ethyl, propyl, butyl and the like). [2] polyethylene glycol monoalkyl ether,
Polyethylene glycol dialkyl ether and the like (as alkyl, for example, methyl, ethyl, propyl, butyl,
Lauryl, cecil, stearyl, oleyl and the like); polypropylene glycol monoalkyl ether, polypropylene glycol dialkyl ether and the like (alkyl is, for example, methyl, ethyl, propyl, butyl, lauryl, cecil, stearyl, oleyl, perfluoroalkyl and the like). [3] polyethylene glycol monoaryl ether,
Polyethylene glycol diaryl ether and the like (aryl is, for example, octylphenyl, nonylphenyl and the like). As these polyalkylene oxides and derivatives thereof, those having a molecular weight in the range of 100 to 10,000 are preferable. This is because a compound having a molecular weight of less than 100 has a small curing promoting effect, and a compound having a molecular weight of more than 10,000 is difficult to dissolve in 2-cyanoacrylate, so that the curing promoting effect is reduced.

In the adhesive composition of the present invention, the preferable addition amount of the curing accelerator is 0.001-1% (more preferably 0.01-0.1%) when the above-mentioned crown compound is used.
%), And 0.01 to 10% (more preferably 0.1 to 1%) when the above alkylene oxide derivative is used. If the addition amount of the curing accelerator is less than the above range, the rapid curability may be insufficient, and if the addition amount exceeds the above range, the storage stability of the composition may decrease.

Other examples of the curing accelerator that can be used include, for example, cyclic sulfur compounds having a polysulfide bond and an ether bond in the molecule described in JP-A-59-64681. When this cyclic sulfur compound is used as a curing accelerator, its addition amount is 0.001 to 5% (more preferably 0.01 to 0.5%).
It is preferable that

Examples of the softening agent used in the present invention include those which do not particularly adversely affect the performance of the cyanoacrylate-based adhesive, and specific examples include, but are not limited to, the following compounds. . [Plasticizer] Phosphate esters include tributyl phosphate, tri-2-ethylhexyl phosphate, triphenyl phosphate, tricresyl phosphate, and the like. Phthalate esters include dimethyl phthalate, diethyl phthalate, and dibutyl phthalate. , Diheptyl phthalate, di-n-octyl phthalate, di-2-ethylhexyl phthalate, diisononyl phthalate, octyl decyl phthalate, diisodecyl phthalate, butyl pentyl phthalate, etc., and dibutyl sebacate as a sebacate ester system And 2-ethylhexyl sebacate, and the like, and oxyacid esters such as acetyl citrate.

[Polyfunctional compound] As an ester having a dipentaerythritol residue as an alcohol residue and an acrylic acid or methacrylic acid residue as an acid residue,
Dipentaerythritol triacrylate (KAYARAD D-330 as a commercial product; manufactured by Nippon Kayaku Co., Ltd.), dipentaerythritol tetraacrylate (KA as a commercial product
YARAD D-320; Nippon Kayaku Co., Ltd.), dipentaerythritol pentaacrylate (KAYARAD D-3 as a commercial product)
10; Nippon Kayaku Co., Ltd.) and dipentaerythritol hexaacrylate (commercially available KAYARAD DPHA
; Nippon Kayaku Co., Ltd.) and modified dipentaerythritol hexaacrylate obtained by modifying dipentaerythritol with caprolactone (KAYARAD DP as a commercial product)
CA-20, KAYARAD DPCA-30, KAYARAD DPCA-60, KAYARAD
DPCA-120; manufactured by Nippon Kayaku Co., Ltd.). Acryloyl group or methacryloyl group (both below
(Meth) acryloyl group and ester based on it
Specific examples of the polyfunctional compound having three or more (meth) acrylates in the molecule include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra
(Meth) acrylate, urethane (meth) acrylate having three or more (meth) acryloyl groups, epoxy (meth)
Acrylate and pentaerythritol-modified poly (meth) acrylate.

[Polymer] polycarbonate diol,
And polyester polyols. Of these,
Preferred softening agents are dimethyl phthalate, diethyl phthalate, dibutyl phthalate and acetyl tributyl citrate. The amount of the softening agent used in the present invention in the 2-cyanoacrylate is preferably 5% by weight to 40% by weight, more preferably 1% by weight, based on the total amount of both.
0% to 30% by weight. If the amount of the plasticizer is less than 5% by weight, a sufficient reinforcing effect cannot be obtained due to poor flexibility, while if it exceeds 40% by weight, the adhesion speed is delayed and the strength is poor.

The cyanoacrylate adhesive composition of the present invention has an acid content of 0.5 × 10 ^-6 as measured by the following method.
Gram equivalent number / g or less (more preferably 0.4 × 10 ⁻⁶ gram equivalent number / g or less). [Method for measuring acid content] A sample obtained by mixing 3 g of the adhesive composition with 90 ml of acetone and further adding 3 ml of distilled water was used as an indicator.
Using a material having a discoloration range of 4.5 to 5.0,
Neutralize and titrate with 100N NaOH aqueous solution. Acid content is 0.
A cyanoacrylate adhesive composition having a content of 5 × 10 ⁻⁶ gram equivalent / g or less has a higher rapid curing property and storage stability than an adhesive composition having a content of more than 0.5 × 10 ⁻⁶ gram equivalent / g. Is also good. It is considered that this is because the acid derived from the acid component promotes the hydrolysis of cyanoacrylate. The lower limit of the acid content is not particularly limited, but if the acid content is reduced more than necessary, the production cost may increase, or the viscosity stability of the composition may decrease.
It is preferred to be 10 ^-6 gram equivalent / g or more.

The specific method of reducing the acid content of the adhesive composition is not particularly limited, as long as the acid content of the composition obtained by any of the various production methods eventually falls below a predetermined value.
For example, in the production of the 2-cyanoacrylate monomer, a method of improving the distillation conditions based on the acid content as a selection criterion, rather than simply selecting the condition in which the total amount of impurities is reduced, may be mentioned.

The indicator used to determine the end point of neutralization when measuring the acid content of the composition is pH 4.5 to 4.5.
It has a discoloration range of 5.0, and specific examples thereof include an indicator such as bromophenol blue, bromocresol blue, and methyl yellow, or a mixed indicator thereof. The use of an indicator having a discoloration range of pH 4.5 to 5.0 excludes an acid component that does not have a particularly bad influence on the cyanoacrylate-based adhesive composition, and accurately grasps only the problematic acid component. It is. Incidentally, the method for measuring the acid content in the present invention is as described above, but if it is difficult to use the indicator, the end point of the neutralization titration should be p.
H may be 4.5 to 5.0, and the neutralization end point may be obtained by an electric method. Furthermore, even if the ratios of cyanoacrylate, acetone and distilled water are slightly different from the numerical values described above, substantially the same values can be obtained as a result.

The following radical polymerization inhibitors, initiators, thickeners, and other additives as desired components can be appropriately added to the cyanoacrylate-based adhesive according to a conventional method. [Radical polymerization inhibitor] As a radical polymerization inhibitor for improving storage stability, for example, hydroquinone or hydroquinone monomethyl ether is added. [Initiator] As a radical initiator, an organic peroxide such as hydroperoxide, peroxyester, ketone peroxide, peroxyketal, dialkyl peroxide, diacyl peroxide, peroxydicarbonate is added. [Thickeners] As thickeners, for example, homopolymers or copolymers of various (meth) acrylates, acrylic rubbers,
A viscous liquid or a liquid having a thixotropic property can be obtained by dissolving or dispersing a cellulose derivative, silica, or the like. [Other additives] Other dyes, pigments, diluents and the like can be added.

The principle that the adhesive composition of the present invention comprising an alkoxyalkyl 2-cyanoacrylate or the like specifically has good storage stability is considered as follows. [Specification of Anion Polymerization Inhibitor] The time-dependent change of the cyanoacrylate-based adhesive composition is mainly caused by the deterioration of viscosity due to polymerization of cyanoacrylate and the deterioration of bonding speed due to hydrolysis of cyanoacrylate. In order to suppress this deterioration, a radical polymerization inhibitor and an anionic polymerization inhibitor are generally blended as stabilizers. The anionic polymerization inhibitor is generally an acidic substance and suppresses viscosity deterioration. However, if the blending amount is too large, hydrolysis is promoted, so that the deterioration of the bonding speed is promoted. On the other hand, if the amount is too small, the deterioration of viscosity cannot be suppressed. Therefore, the compounding amount is determined from the amount which suppresses the viscosity deterioration and hardly causes the adhesion speed deterioration. Known anionic polymerization inhibitors require a relatively small amount of alkyl 2-cyanoacrylate to suppress the viscosity deterioration over a long period of time. Thus, an adhesive composition having good storage stability can be prepared. However, in an alkoxyalkyl 2-cyanoacrylate or the like, such a relationship does not hold.
Addition of an anion polymerization inhibitor other than the present invention as an anion polymerization inhibitor such as 2-cyanoacrylate in an amount necessary to suppress the viscosity deterioration over a long period of time significantly accelerates the adhesion speed deterioration. Conversely, if the compounding amount is reduced in order to suppress the deterioration of the bonding speed over a long period of time, the viscosity deteriorates remarkably quickly. Therefore, even if a balanced blending amount is determined, the storage stability of the adhesive composition is not good. On the other hand, in the specific anion polymerization inhibitor described above, there is an amount that suppresses the viscosity deterioration with respect to the alkoxyalkyl 2-cyanoacrylate and the like, and that the adhesion speed deterioration hardly occurs. Using the agent,
Only by controlling the amount of the acid content below a certain level, a cyanoacrylate-based adhesive mainly composed of alkoxyalkyl 2-cyanoacrylate having good storage stability can be prepared.

[Reduction of Acid Content] During the production of 2-cyanoacrylate, 2-cyanoacrylic acid and cyanoacetic acid are by-produced. 2-Cyanoacrylic acid can be generated by hydrolysis of a 2-cyanoacrylate monomer and the like. Cyanoacetic acid also
Cyanoacetate, one of the raw materials used in a general method for producing a 2-cyanoacrylate monomer,
Hydrolysis may occur during the production or purification stage of the 2-cyanoacrylate monomer. The purification method of 2-cyanoacrylate is generally performed by distillation, but since alkoxyalkyl 2-cyanoacrylate and the like have a high boiling point, distillation of alkoxyalkyl 2-cyanoacrylate and the like is performed at a higher temperature than alkyl 2-cyanoacrylate. Will be Therefore, the above acidic component is alkyl 2-
It is more likely to occur in the production of alkoxyalkyl 2-cyanoacrylate and the like than in cyanoacrylate. These acids acted as catalysts for accelerating the hydrolysis of 2-cyanoacrylate and hindered the storage stability of cyanoacrylate-based adhesives containing alkoxyalkyl 2-cyanoacrylate or the like as a main component. These acidic components can be measured by the above-described method, and it is necessary to suppress the amount to 0.5 × 10 ⁻⁶ gram equivalent number / g or less in order to stabilize the adhesive composition. As a result, as described above, the storage stability of the cyanoacrylate-based adhesive containing alkoxyalkyl 2-cyanoacrylate or the like as a main component could be improved.

[0024]

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. Examples 1 to 16, Comparative Examples 1 to 8 O Storage stability test An adhesive having the composition shown in Tables 1 and 2 was prepared by a conventional method, and the storage stability was evaluated as follows. [Forced Deterioration Test] Adhesive was put in a polyethylene container, aluminum-packed, then placed in a thermostat at 60 ° C. and left for 20 days to be forcibly degraded. The results are shown in Tables 1 and 2 together with those before the forced deterioration. [Adhesion speed] Hard vinyl chloride was used as a test piece and JI
The measurement was performed according to the SK6861 set time test method. [Viscosity] The viscosity at 25 ° C. was measured with an E-type viscometer.

[0025]

[Table 1]

[0026]

[Table 2]

As is clear from Tables 1 and 2, the composition of the present invention has a high initial adhesion speed, the same adhesion speed and viscosity after storage stability test as those of the initial stage, and good storage stability. I understand. On the other hand, the composition shown in Comparative Example
The initial bonding speed is low, the bonding speed after the storage stability test is low, the viscosity is inferior to the composition of the present invention such as thickening, and the composition of the present invention is superior to the comparative example. It turns out there is.

Measurement of cured product hardness, pungent odor, adhesive strength, and adhesive speed An adhesive having the composition shown in Table 3 was prepared by a conventional method, and the properties thereof were measured by the following methods. And the composition of the present invention was evaluated. [Hardness of cured product and irritating odor] Regarding the irritating odor, a circle was given in a case where the odor was better than that of the comparative example. The hardness was evaluated using a Shore hardness meter D type. [Adhesion speed] Hard vinyl chloride was used as a test piece and JI
The measurement was performed according to the SK6861 set time test method. [Adhesive strength] Chloroprene rubber was used as a test piece.
It was measured in accordance with the ISK6861 tensile shear bond strength test method. In the table, x indicates substrate failure, and Δ indicates partial substrate failure.

[0029]

[Table 3]

As is clear from Table 3, the composition of the present invention has a low pungent odor, and the composition containing a softening agent exhibits a flexibility of about 50 or less in Shore hardness D. Furthermore, the adhesive speed is high, and the adhesive strength of the chloroprene rubber is such that the substrate is broken or partially broken, indicating that it is excellent. On the other hand, the composition shown in Comparative Example had a large irritating odor and was inferior to the composition of the present invention, indicating that the composition of the present invention was superior to the comparative example.

[0031]

Industrial Applicability The cyanoacrylate adhesive composition of the present invention solves the pungent odor and the whitening phenomenon, and has excellent storage stability and instant adhesiveness, and further imparts flexibility. You can also. Instantaneous adhesives having such properties are widely used in more applications than conventional ones, and are very effective not only in various industries but also in ordinary households.

Claims (5)

[Claims] 1. An alkoxyalkyl 2-cyanoacrylate or tetrahydrofurfuryl 2-cyanoacrylate as a main component, containing boron trifluoride or a boron trifluoride complex salt as an anionic polymerization inhibitor, and measured by the following method. A cyanoacrylate adhesive composition having an acid content of 0.5 × 10 ⁻⁶ gram equivalent / g or less. [Method of measuring acid content] A sample obtained by mixing 3 g of the adhesive composition with 90 ml of acetone and further adding 3 ml of distilled water was used to obtain a sample having a pH of 4.5 to 5.5.
Neutralization titration is carried out with a 1 / 100N aqueous NaOH solution using an indicator having a discoloration range of 0. 2. The cyanoacrylate adhesive composition according to claim 1, wherein the boron trifluoride complex salt is an alcohol salt or an ether salt. 3. The cyanoacrylate adhesive composition according to claim 1, further comprising a curing accelerator. 4. The method according to claim 3, wherein the curing accelerator is selected from crown ethers and their analogs, polyalkylene oxides and their derivatives.
A cyanoacrylate adhesive composition. 5. The cyanoacrylate adhesive composition according to claim 1, further comprising a softening agent.