English

This invention relates to a process for curing polyepoxides. More particularly, this invention relates to a new process for curing polyepoxides, to novel curing agents used in the process, and to useful products obtained from the process.

The disclosed compounds are adducts of imidazole or derivatives thereof and sulfur dioxide. The adducts are apparently of the Lewis acid-Lewis base type, and are useful as latent curing agents for epoxide resins. The adducts are prepared by interacting the imidazole and sulfur dioxide under anhydrous conditions. Equimolar imidazole--SO.sub.2 adducts can serve as a source of sulfur dioxide at room temperature.

This invention relates to the reaction of organic substituted hydrazines with sulfur dioxide. In one specific aspect, it relates to a novel process for making organic substituted hydrazinium hydrazinesulfinates. In yet another aspect, it relates to the composition of matter produced thereby.

My invention relates to improvements in blowing agents for the manufacture of porous rubber and plastic articles. Foamed articles of plastics or rubber are prepared by various means including solution of nitrogen under high pressures and subsequent release of pressure. A simpler method is to incorporated in the rubber or plastic composition a suitable chemical agent which, on heating to vulcanization or molding temperatures, releases large quantities of gas and thus causes foaming of the composition.

Gaseous sulfurdioxide reacts with 1,1-dimethylhydrazine, N-aminopiperidine, N-aminohomopiperidine, and N-aminomorpholine to form 1:1 adducts. The adducts are formed between the nitrogen atom of the R2N group in the hydrazine and the sulfur atom in sulfurdioxide. Analytical, proton NMR and i.r. spectral data are given.

Some new cyanoacetates were synthesized and characterized. They are precursors for α-cyanoacrylates used as rapidly polymerized, cold-hardening adhesives.

An adhesive composition comprising monomeric methyl allyl methylenemalonate is useful for bonding together a wide range of materials.

Alicyclic mono and diacrylates from alpha-pinene and beta-pinene derivatives were synthesised and characterized spectroscopically. They were then compounded in alkyl 2-cyanoacrylate adhesives as crosslinkers. Their effect on the adhesive bond strengths after exposing the adhesive bonds to various temperatures, was studied.

Polyalkyl 2-cyanoacrylates begin to retropolymerize and deteriorate dramatically at temperatures above 80°C. They bond rapidly to the metal surfaces and readily lose strength even at ambient temperatures. These two drawbacks of the cyanoacrylates have made this class of adhesives unpopular as structural adhesives. Several attempts have been made to increase the thermal stability and the stability of the bond between the metal surfaces by adding chemicals like cyclopentadienoates and anhydrides to the cyanoacrylates.