JPS621429B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a 2-cyanoacrylate adhesive composition that has excellent storage stability, improved wetting properties during application, and provides good adhesive strength. 2-Cyanoacrylate is an adhesive that instantly hardens with trace amounts of moisture in the atmosphere, and is used to bond rubber, plastics, metals, wood, and the like. However, 2-cyanoacrylate adhesives have the disadvantage that during storage in a container, they begin to polymerize, increase in viscosity, and eventually harden. For this reason, various stabilizers for 2-cyanoacrylate adhesives have been studied, including acid gases such as SO ₂ , HF, and NO, and p-cyanoacrylate adhesives.
Toluenesulfonic acid, methanesulfonic acid, sultone, etc. are used. These stabilizers are 2
-It is effective as an anionic polymerization inhibitor for cyanoacrylate, but it has drawbacks such as slow curing speed when slightly excessive, and it also has the disadvantage of coloring the 2-cyanoacrylate adhesive during storage. be. When using instant adhesives, a prerequisite for obtaining good adhesive strength is that the surface of the adherend is quickly covered with adhesive and there are no chips before the adhesive is applied and cured. However, conventional stabilizers have been insufficient in terms of improving surface properties or wetting. The present inventors improved the surface properties or wetting properties of such 2-cyanoacrylate adhesives, and as a result of investigating various stabilizers with excellent storage stability, they found that certain sulfonic acids and carboxylic acids are excellent. The present invention was completed based on the discovery that That is, the present invention is an adhesive composition comprising 2-cyanoacrylate and at least one compound represented by the following general formula. General formula Rf−SO ₃ H, Rf−COOH,

【formula】

[Formula] However, Rf is a perfluoroalkyl group or pentafluorophenyl group whose alkyl group has 1 to 12 carbon atoms, and R′f is an alkylene group whose carbon number is 2 to 12.
12 perfluoroalkylene group or tetrafluorophenylene group. The adhesive composition of the present invention in which sulfonic acid or carboxylic acid represented by the above general formula is blended with 2-cyanoacrylate has the advantage of improved storage stability and wetting properties of the adhesive compared to conventional ones. It is something that you have. In addition, SO ₂ , which has been most commonly used in the past, has had the disadvantage of decreasing over time in adhesive compositions, but the sulfonic acid or carboxylic acid represented by the above general formula in the present invention does not decrease over time. No changes observed. Furthermore, in addition to the fact that the initial adhesion performance of the stabilizer does not change much even after storage, it also improves the permeability of the adhesive into the surface of the adherend, reduces the number of cracks, and reduces the amount of adhesive used per unit area. The surface chemical properties of the adhesive, such as increased adhesion speed, are significantly improved, and the adhesive of the present invention is excellent as an instant adhesive. Examples of the 2-cyanoacrylate in the present invention include the following esters. For example, methyl
Alkyl esters such as ethyl, propyl, butyl, heptyl, hexyl, octyl and dodecyl; cyclohexyl esters; alkenyl and alkynyl esters such as allyl, crotyl and propargyl; halogenated alkyl esters such as 2-chloroethyl and perfluoroalkyl; Examples include esters having an ether bond such as methoxyethyl, 2-ethoxyethyl, 3-methoxybutyl, and tetrahydrofurfuryl. The sulfonic acid or carboxylic acid used as a stabilizer in the present invention is represented by the following general formula. Rf− _SO3H , Rf−COOH,

【formula】

[Formula] Rf is a perfluoroalkyl group or pentafluorophenyl group whose alkyl group has 1 to 12 carbon atoms, and R′f is a perfluoroalkylene group or tetrafluorophenyl group whose alkylene group has 2 to 12 carbon atoms. It is a nylene group. Specifically, trifluoromethanesulfonic acid,
Pentafluorobenzenesulfonic acid, perfluorobutanesulfonic acid, trifluoroacetic acid, pentafluoropropionic acid, perfluorobutyric acid, perfluorooctanoitsuccinic acid, perfluorodocainoitsucnic acid, perfluorolauric acid, pentafluorobenzoic acid, Perfluorosuccinic acid (or its anhydride), difluorosuccinic acid (or its anhydride), perfluoroglutaric acid (or its anhydride), perfluoroadipic acid, tetrafluorophthalic acid (or its anhydride), etc. It will be done. In the present invention, it is not preferable that the alkyl group or alkylene group of the sulfonic acid or carboxylic acid represented by the above general formula has 13 or more carbon atoms because the solubility in 2-cyanoacrylate becomes poor. In the present invention, the sulfonic acid or carboxylic acid represented by the general formula is added in an amount of 0.1 to 1000 ppm, preferably 1 to 100 ppm, based on the 2-cyanoacrylate. If the amount added is less than this, polymerization tends to occur easily, and if it is added more than this, the adhesion speed tends to be slow. The adhesive composition of the present invention contains conventional SO ₂ , alkyl or aryl sulfonic acids,
It may be used in combination with sultone, etc. In addition, hydroquinone, hydroquinone monomethyl ether, catechol, etc. are often used in combination.
Also, to obtain a high viscosity adhesive, several percent of methyl methacrylate polymer or cellulose ester is added. The present invention will be specifically described below with reference to Examples. Example 1 0.002 g of trifluoroacetic acid and 0.01 g of hydroquinone were added to 100 g of ethyl 2-cyanoacrylate and mixed for 1 hour. When this was stored in a 20g polyethylene container at 23℃ and 60%RH for 6 months, the setting time of the iron was 10 to 20 seconds, and the hard PVC
The set time was 5 to 10 seconds, which was the same as at the beginning of the preparation. Tensile shear adhesive strength of iron (JIS
K6850) was 210Kgf/ ^cm2 . Example 2 100 g of methyl 2-cyanoacrylate, 0.0002 g of trifluoromethanesulfonic acid, 0.02 g of hydroquinone monomethyl ether, and 5 g of polymethyl methacrylate were mixed and stirred to prepare an adhesive having a viscosity of 200 cp. When filled in a 20g polyethylene container and stored at 23℃ and 60%RH for 6 months, the setting time for iron was 10 to 20 seconds, and the setting time for hard PVC was 5 to 10 seconds, which was almost unchanged from the initial stage of preparation. I hadn't done it. The tensile shear adhesive strength of iron was 250 Kgf/cm ² . Examples 3 to 10 and Comparative Examples 1 to 2 100 g of ethyl 2-cyanoacrylate, 0.01 g of hydroquinone, and the stabilizers shown in Table 1 were added and the stability and strength were measured in the same manner as in Example 1. The results were as follows: It is as shown in Table-1.

[Table] Examples 11 to 14 and Comparative Example 3 In order to investigate the excellent permeability of the adhesive of the present invention, a male-female mating adhesion test was conducted. That is,
Adhesives 3 to 4 made of methyl cyanoacrylate and the stabilizer shown in Table 2 were applied to aluminum female and brass male mold frames with a mating part diameter of 12 mm, depth of 23 mm, area of 8.7 cm ² and clearance of 20 μ. Drip flow, 23℃,
Table 2 shows the results of measuring the pull-out strength after curing at 60% RH for 24 hours. The strength values are the minimum and maximum values of five tests.

【table】

Claims (1)

[Scope of Claims] 1. An adhesive composition comprising 2-cyanoacrylate and at least one compound represented by the following general formula. General formula Rf-SO ₃ H, Rf-COOH, [Formula] [Formula] However, Rf is a perfluoroalkyl group or pentafluorophenyl group in which the alkyl group has 1 to 12 carbon atoms, and R′f is an alkylene group. The number of carbon atoms in the group is 2~
12 perfluoroalkylene group or tetrafluorophenylene group.