Cyanoacrylate is a strong, fast-setting, instant adhesive. Easily bonds a variety of non-porous and water-containing materials. It sets in less than a minute and reaches maximum strength in two hours. The shear strength of the adhesive is low, therefore superglue is sometimes used as a thread lock or for temporary fastening of a workpiece on a lathe, etc.
"Superglue" is a liquid monomer of one or another cyanoacrylate (methyl-, ethyl- etc.) with the possible addition of up to 10% of plasticizers (for example, dibutyl phthalate in the domestic glue Cyacrin), activators (with insufficient joint moisture), stabilizers, retarders, as well as ultradispersed silicon oxide for thickening (gel superglue); the adhesive does not contain solvents.
Liquid cyanoacrylate is capable of anionic polymerization under the action of weakly alkaline agents, including ordinary water [4]. The continuous hardening of "superglue" in thin layers (within 0.05-0.1 mm) is caused by moisture adsorbed on the glued surfaces or contained in the surface layers of the material (which, along with the effect of animal amines, explains the excellent sticking of fingers). The harmful solidification of the glue mass during storage in a loosely closed container is caused not by the evaporation of the solvent, as in the case of nitrocellulose glue or PVA, but by the effect of atmospheric moisture (as is typical, for example, of silicone sealants); during production, the glue clogs up in a dry atmosphere. Also, according to the manufacturer's descriptions, there is a curing mechanism with an alkaline agent associated with the neutralization of the acid stabilizer.
For working with cyanoacrylate in thick layers, an amateur method is known with successive filling of the seam with baking soda moistened with superglue and playing in this case, the role of not only a filler, but also an alkaline polymerizing agent. The mixture hardens almost instantly, forming an acrylic-like filled plastic, and in some cases can successfully replace epoxy compositions, including those reinforced with glass mesh. You can also use finely ground plaster or concrete as filler, such as dust from drilling holes in such materials.
Although the initial setting of the adhesive does occur in seconds to minutes, manufacturers prescribe curing for the final curing connections in the air without work load for several (up to 24) hours.
Safety when working with adhesive
Attempting to glue materials containing cellulose (eg cotton) may result in an intense exothermic reaction. The released heat can cause burns if large amounts of cyanoacrylate are used.
The Material Safety Data Sheet for cyanoacrylate prohibits the wearing of cotton or wool clothing, especially cotton gloves, when handling the adhesive when handling or transporting cyanoacrylate.
Cyanoacrylate vapors, which are monomers, may irritate the mucous membranes of the eyes, nose and throat. But with sufficient concentration, they instantly polymerize under the influence of moisture and become inert. It is believed that the risk may be negligible if working in a well-ventilated area. With regular exposure to cyanoacrylate, about 5% of people experience flu-like symptoms. Cyanoacrylate can also irritate the skin and cause allergic skin reactions. In rare cases, inhalation of vapors can cause asthma.
For different cyanoacrylates, the toxicity can vary significantly.