Hexamethylene diamine carbamate

Amine Cross-Linking. Two commercially important, high performance elastomers which are not normally sulfur-cured are the fluoroelastomers (FKM) and the polyacrylates (ACM). Polyacrylates typically contain a small percent of a reactive monomer designed to react with amine curatives such as hexamethylene-diamine carbamate (Diak 1). Because the type and level of reactive monomer varies with ACM type, it is important to match the curative type to the particular ACM ia questioa. Sulfur and sulfur-beating materials can be used as cure retarders they also serve as age resistors (22). Fluoroelastomer cure systems typically utilize amines as the primary cross-linking agent and metal oxides as acid acceptors. 

FIGURE 3.5 Fourier Transform infrared (FTIR) spectra of acrylic rubber (ACM)-siUca hybrid nanocomposites. The numbers after ACM (10 and 50) indicate the wt% tetraethoxysilane (TEOS) concentration. The letters preceding the numbers indicate the ACM-silica samples cross-linked from benzoyl peroxide (B) and a mixed cross-linker hexamethylene diamine carbamate and ammonium benzoate (D). The numbers over the absorption peaks are the wave numbers corresponding to absorbance of those peaks. (From Bandyopadhyay, A., Bhowmick, A.K., and De Sarkar, M., J. Appl. Polym. Sci., 93, 2579, 2004. Courtesy of Wiley InterScience.)... 

Total a Hexamethylene diamine carbamate (curing agent). 138.0 136.2... 

Free diamines, used for cross-linking, are too reactive and can cause premature gelation. It is common practice, therefore, to add these diamine compounds in the form of carbamates, like ethylenediamine carbamate or hexamethylene diamine carbamate. The above fluoro elastomers exhibit good resistance to chemicals and maintain useful properties from —50 to -i-300°C. 

HMDA Carbamate [Hexamethylene diamine carbamate—Diak No. 1... 

Compound parts polymer, 100 Naugard 445 (substituted diphenylamine), 2 Armeen 18D (octadecylamine), 0.5 stearic acid, 1.5 Vanfre VAM (complex organic aUsyl acid), 1.0 FEF Carbon Black (N550), 60 DIAK 1 (hexamethylene-diamine carbamate), 1.5 and DOTG, 4. 

The early forms of VITON processed poorly and were hard to cure. The Kellogg chemists had discovered that their CTPE/VF2 elastomer could be cured with hexamethylene diamine carbamate which also was effective with VITON , but the compounds were very scorchy. Thermal stability of the cured products was good but poorer than the raw polymer because the curing reactions introduced olefinic bonds and a relatively unstable crosslink. More Importantly for critical sealing applications high temperature compression set fell far short of demands. Further research delivered delayed action amine type curing agents which improved processability. 

Copper inhibitor 65 containing di-salicylal propylene diamine has a retarding effect at processing temperature, but activates cure. Diak Nol (hexamethylene diamine carbamate) is the vulcanizing agent. 

The elastomers based on vinylidene fluoride are saturated and cannot be vulcanized with sulphur. As with other saturated rubbers cross-linking can be brought about by irradiation and by the use of peroxides but the only agents of commercial importance until the 1970s were diamines and certain of their derivatives. Of particular importance have been the amine carbamates which are somewhat less reactive and less likely to scorch (premature vulcanization) during processing. Typical materials of this class are ethylene diamine carbamate (IX), hexamethylene diamine carbamate (X) and N,N -dicinnamylidene-1,6-hexane diamine (XI) ... 

Vulcanization may be brought about by amines such as tetraethy-lene pentamine and hexamethylene diamine carbamate. It is believed that the process involves reaction of the diamine with the para fluorine atom on the aromatic ring ... 

The use of amine derivatives used for curing fluoroelastomers such as hexamethylene diamine carbamate and N,N -dicinnamylidine-1,6-hexane diamine has also been recommended. 

Vulcanization of the epichlorhydrin rubbers is normally brought about by reaction of the chloromethyl group with diamines and polyamines or their derivatives such as hexamethylene diamine carbamate, with 2-mercaptobenzimidazoline, with lead oxide and lead phosphite, and with ammonium salts. The processes are analogous to those used with the polychloroprenes and with those acrylic rubbers containing a halogenated cure site. A sulphur-curable grade was announced in late 1977. 

Struktol WB 42 at a 1 % level, combined with 1 % stearic acid, is a good combination for general purpose use in peroxide-cured AEM ethylene acrylic elastomer compounds. Vamac AEM stocks using hexamethylene diamine carbamate (Diak No. 1) as the curative, requires 1% stearic acid plus 0.3% of a stearamide such as Armeen 18D from Akzo and 0.8% of Struktol WS 180. These chemicals act as coagents for mill release. Struktol WB 42, Struktol WS 180, and Armeen 18D also serve as mold release agents. 

GL Glass fiber DIN, EDV) HMDAC Hexamethylene diamine carbamate... 

In this article we are told that SEC Gummimischungen GMBH of Germany, a specialty compound distributor, has developed a hexamethylene diamine carbamate curing agent, HMDC-Batch , which is designed for curing fluoroelastomers and ethylene acrylic elastomers. 

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