Лако-красочные материалы — производство

A large number of variations are possible for anaerobic curing products, but all will consist of the following components:

1. Monomer. Methacrylate esters are used in almost all anaerobic products. Acrylates, acrylic and methacrylic acids, and few other vinyl polymerizable monomers may be used for special purposes.

2. Initiator. A hydroperoxide (typically, cumene hydroperoxide) is almost always used as an initiator, although there are some variations and it is also possible to take advantage of small amounts of ‘‘native’’ hydroperoxide present in the methacrylate monomers.

3. Accelerator. A large number of chemical accelerators have been developed which can catalyze the anaerobic cure and reduce the large differences in cure speed on different surfaces. The most commonly used accelerators are saccharin [benzoic sulfimide (II)] and aromatic amines such as N, N-dimethyl-p-toluidine (III) and 1,2,3,4-tetrahydroquinoline (IV).

4. Stabilizers. All methacrylate monomers must contain some free-radical inhibitor if they are to be shipped and stored safely. Hydroquinone and p-methoxyphenol are most commonly used for this purpose. Most formulations will also contain benzoquinone, naphthoquinone, and similar stabilizers. Since the anaerobic compositions are strongly catalyzed by traces of metals, many formulators have found it advantageous to add chelators such as tetrasodium ethylenediaminetetraacetic acid (EDTA) (V).

5. Modifiers. A very large number of modifications in the cured and uncured properties of anaerobic formulations can be brought about by the addition of components that have little or no effect on the fundamental anaerobic cure chemistry. These modifiers can increase the viscosity, control thixotropy, add color or fluorescence, increase sealing effectiveness, reduce strength, increase toughness, increase heat resistance, provide lubri­cation, and reduce settling of fillers.

6. Surface activators. In some applications anaerobic sealants will cure more rapidly if the surface is treated with a solution containing a metal salt or other chemical that will catalyze the polymerization. These substances will often be components that could not be added to the sealant without causing premature gellation.