JPS6212279B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for bonding leather, wood materials, etc. using an α-cyanoacrylate adhesive. The purpose of this is to treat porous and acidic materials such as leather and wood materials with an α-cyanoacrylate adhesive beforehand by treating the surface to be adhered with a surfactant solution. By doing so, it is possible to accelerate the setting time and obtain strong adhesive strength. α-Cyanoacrylate adhesives have the feature that a small amount of moisture adhering to the surface of the adhered material acts as an anionic polymerization initiator, and it can firmly bond almost any material within a few seconds to a few minutes. Because of this, it is widely used in industries, industries, medical fields, cash registers, and general households. The demand for α-cyanoacrylate adhesives is growing steadily in various fields as described above, but when the adhered material is porous and acidic, such as leather or wood, α-cyanoacrylate The adhesive penetrates into the material, and the anionic polymerization reaction of the α-cyanoacrylate adhesive is hindered, making it impossible to achieve good adhesion. Leather is composed of collagen protein as its main component, and is inherently porous, as well as being acidic due to the tanning operations that include tannin and chromium during the leather manufacturing process. Furthermore, although wood is mainly composed of cellulose, hemicellulose, and lignin, it also contains other minor components such as fatty acids such as palmitic acid and stearic acid, so it is similarly acidic. α-cyanoacrylate adhesives are generally used as a means of preventing penetration of α-cyanoacrylate adhesives into porous materials.
A method using a thickened form of cyanoacrylate adhesive is used, but for the adherend material that is the object of the present invention, simply increasing the viscosity of α-cyanoacrylate adhesive is insufficient. cannot achieve the purpose. In the past, the present inventors had made various proposals regarding bonding methods for materials with difficult adhesive properties, but as a result of further improvements, the present invention was completed. This bonding method is characterized in that when bonding porous and acidic materials using a surfactant, the surface of the materials is treated in advance with a surfactant solution. Surfactants effective in the present invention include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants, and specific examples include the following. Examples of anionic surfactants include sodium oleate, potassium oleate, sodium lauryl sulfate, triethanolamine lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium dodecylnaphthalenesulfonate, formalin condensate of naphthalenesulfonate, Examples include sodium dialkyl sulfosuccinate and sodium polyoxyethylene lauryl ether sulfate. Examples of the cationic surfactant include laurylamine acetate, dodecyltrimethylammonium bromide, polyoxyethylene laurylamine, and the like. Examples of amphoteric surfactants include lauryl betaine and stearyl betaine. Examples of nonionic surfactants include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene nonylphenol ether, sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate, and Examples include oxyethylene sorbitan monolaurate, polyethylene glycol monolaurate, polyethylene glycol distearate, oxyethylene oxypropylene block polymer, glyceryl monostearate, and glyceryl monooleate. A surfactant solution is prepared by dissolving the above-mentioned surfactant in water, alcohol, or a mixture of water/alcohol at any ratio, but the concentration of the main component surfactant depends on the type. It's different though
The concentration needs to be 10% by weight or less, and preferably 0.1% by weight or more. If the concentration of the surfactant is too low, the treatment effect will be poor; if the concentration is too high, on the other hand, the amount of adsorption will increase, and if the concentration exceeds the saturation value, this will tend to impede adhesion, which is not preferred. The principles by which surfactants act effectively in surface treatment are thought to be due to improvements in adhesive wetting by lowering interfacial tension, improvement in affinity by alignment effects, and emulsifying effects of oils and fats. The α-cyanoacrylate monomer that is the base of the α-cyanoacrylate adhesive used in the present invention has the general formula

Represented by [Formula]. However, R is methyl, ethyl, n-propyl,
These include alkyl groups such as iso-butyl groups, cycloalkyl groups such as cyclohexyl groups, and aralkyl groups such as allyl groups. To these monomers, for example, trace amounts of hydroquinone and sulfur dioxide gas are added as polymerization inhibitors to improve storage stability. In addition, α-cyanoacrylate monomer is originally a colorless and transparent low-viscosity liquid, but it can be made into a viscous liquid by dissolving a thickener such as polymethyl methacrylate, acrylic rubber, or cellulose derivative. It is also possible to use dyes or dyes colored with specific dyes. In the present invention, the surface of porous and acidic materials such as leather and wood materials is treated with a surfactant solution, and the method is to wipe it with a cloth impregnated with a surfactant solution, or This is done by bringing the surface into contact with a surfactant solution, such as by immersing the surface in a surfactant solution. Usually, after treatment, the material is left to dry and then bonded with an α-cyanoacrylate adhesive. Thus, the present invention can provide excellent bond strength with fast set times even for bonding porous and acidic materials. The present invention will be specifically explained below using Examples and Comparative Examples. Note that % is based on weight. The test method is JISK6361 "α" described below.
- Test method for cyanoacrylate adhesives. (1) Set time (a) When the test piece is leather Leather (tanned) 0.5 thickness x 2.5 width x 50
Wipe both sides of the long mm-long adhesion surface with a cloth impregnated with a surfactant solution, leave it for about 1 minute, then apply cyanoacrylate adhesive to one side, overlap it by 10 mm, and bond it. A tensile shearing load of 1.25 kg/0.25 ^cm2
(5Kgf/cm ² ) was measured. (b) When the test piece is wood: Wood lauan or cypress 5 thickness x 25 width x 50 length mm
Wipe both sides of the plate surface with a cloth impregnated with a surfactant solution, leave it for about 1 minute, then apply cyanoacrylate adhesive to one side, overlap it by 10mm, and bond it.The tensile shearing load is 12.5Kg/cm ² (5Kgf). /
cm ² ) was measured. (2) Tensile shear adhesive strength The test piece used was leather. Adhesion was carried out in the same manner as in the case of the set time measurement, and after being left for 24 hours, measurement was performed using a Strograph W type universal testing machine at a loading rate of 50 mm/min. (3) Compression shear adhesive strength The test piece used was wood. Adhesion was carried out in the same manner as in the case of the set time measurement, and after being left for 24 hours, measurement was performed using a Strograph W type universal testing machine at a loading rate of 10 mm/min. The measurement conditions were 23±1°C and 60±2%RH. Example 1 and Comparative Example 1 Anionic surfactant sodium oleate,
The cationic surfactant polyoxyethylene laurylamine, the amphoteric surfactant lauryl betaine, and the nonionic surfactants polyoxyethylene lauryl ether and polyoxyethylene nonyl phenyl ether were dissolved in distilled water to give 0.1% or 1
% aqueous solution was prepared. Using this surfactant liquid, an adhesion test was conducted on the materials shown in Table 1 according to the test method described above. Note that Comparative Example 1 is a case where the adhesive was bonded without any treatment, and the test results are shown in Table 1.

[Table] Example 2 and Comparative Example 2 Anionic surfactant naphthalene sulfonic acid formalin condensate, cationic surfactant laurylamine acetate, amphoteric surfactant lauryl betaine, nonionic surfactant oxyethylene oxypropylene block A 1% ethanol solution of each of the polymers was prepared. Using this surfactant, an adhesion test was conducted on the materials shown in Table 2 according to the test method described above. Note that Comparative Example 2 is a case where the adhesive was bonded without any treatment, and the test results are shown in Table 2.

[Table] Example 3 The cationic surfactant polyoxyethylene laurylamine and the amphoteric surfactant lauryl betaine were dissolved in distilled water to give 10%, 5%, 0.5%, and 0.1%, respectively.
% of each aqueous solution was prepared. Using this surfactant composition liquid, an adhesion test was conducted on the materials shown in Table 3 according to the test method described above. The test results are shown in Table 3.

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Claims (1)

[Claims] 1. An adhesion method for adhering porous and acidic materials using an α-cyanoacrylate adhesive, which comprises treating the surface of the material in advance with a surfactant solution having a concentration of 10% by weight or less.