Anaerobic resins, those which will not cure in the presence of oxygen, but will cure in the presence of nitrogen or other inert gas, i.e., upon exclusion of oxygen, are well known in the art. Such resins generally contain: polyacrylics, such as diacrylates or triacrylates which polymerize by addition through a double bond; optional vinyl material or epoxy resin; an accelerator, usually a tertiary amine, for example, a N,N'-dialkylarylamine, such as N,N'-dimethyl-p-toluidine or N,N'-diethyl-p-toluidine; a coaccelerator, usually an organic sulfimide such as benzoic sulfimide; a free radical initiator, such as cumene hydroperoxide or t-butyl perbenzoate; and a stabilizer for the initiator, such as hydroquinone.
Smith et al., in U.S. Pat. Nos. 4,160,178 and 4,239,802, and Bich et al., in U.S. Pat. Nos. 4,442,138, utilized acrylic resin-vinyl monomer anaerobic type systems, catalyzed with cumene hydroperoxide, and cure accelerated with a combination of N,N'-dimethyl-p-toluidine and benzoic sulfimide. Both of these Smith at al. patents, as well as the Bich et al. patent, give a detailed description of anaerobic cure chemistry and the wide variety of useful monomers and other resin components, and reference may be made to them for such details.
It has been found that N,N'-dialkylarylamines, such an N,N'-dimethyl-p-toluidine and N,N'-diethyl-p-toluidine are among the few amine accelerators that give completely hard cured resins in flowing nitrogen. However, in using these accelerators, cure reactivity is reduced, causing longer resin gel times. Substituting basic aliphatic amides for the N,N'-dialkylarylamines, provides good gel activity but results in softer cured resins, lacking in tensile strength properties. It has also been found that organic sulfimides additionally help to limit reactivity and can cause phase separations and other solubility problems.
Others have tried different combinations of accelerators for anaerobic compositions, for example, Gruber et al. in U.S. Pat. No. 3,985,943 used disulfonamides aong with N,N'-dimethyl-p-toluidine or tri-n-butylamine, and Boeder, in U.S. Pat. No. 4,316,000 used a perfluoroalkyl sulfonanilide along with N,N'-dimethyl-p-toluidine. Although these teachings provide various good bonding and fast gel characteristics, what is needed are additional, improved, co-reactive materials specifically for tertiary amine accelerators in an anaerobic system, which will provide fast gel times as well as a hard cure.