Dicyanodiamides amines

In Chapter 2 the DSC technique is discussed in terms of instruments, experimental methods, and ways of analysing the kinetic data. Chapter 3 provides a brief summary of epoxy resin curing reactions. Results of studies on the application of DSC to the cure of epoxy resins are reviewed and discussed in Chapter 4. These results are concerned with the use of carboxylic acid anhydrides, primary and secondary amines, dicyanodiamide, and imidazoles as curing agents. 

CAS 461-58-5 EINECS/ELINCS 207-312-8 Synonyms Cyanoguanidine N-Cyanoguanidine DCD Dicy Dicyandi-amin Dicyanodiamide Classification Aliphatic organic compd. 

Chemical clusters can be obtained also with two monomers, when two reaction mechanisms are in competition, favoring formation of regions of higher and lower crosslink densities. This situation is more complex and more difficult to control. It is certainly the case for dicyanodiamide (Dicy)-cured epoxies with this hardener an accelerator is always used and a competition between step (epoxy-amine addition) and chain (epoxy homopolymerization) occurs (Chapter 2), leading to inhomogeneous networks. 

Also, N-trimethylsilyl-N -phenylcarbonylcarbodiimide is obtained from PhCONHCN and trimethylchlorosilane." Bis(trimethylsilyl)amine or 2,4,6-tris(trimethylsilylamino)-l,3,5-triazine react with dicyanodiamide to give bis(trimethylsilyl)carbodiimide. ... 

Adhesives which are meant to cure at temperatures of 120 or 171°C require curatives which are latent at room temperature, but react quickly at the cure temperatures. Dicyanodiamide [461-58-5], (TH INI is one such latent curative for epoxy resins. It is insoluble in the epoxy at room temperature but rapidly solubilizes at elevated temperatures. Other latent curatives for 171°C are complexes of imidazoles with transition metals, complexes of Lewis acids (eg, boron trifluoride and amines), and diaminodiphenylsulfone, which is also used as a curing agent in high performance composites. For materials which cure at lower temperatures (120°C), these curing agents can be made more soluble by alkylation of dicyanodiamide. Other materials providing latency at room temperature but rapid cure at 120°C are the blocked isocyanates, such as the reaction products of toluene diisocyanate and amines. At 120°C the blocked isocyanate decomposes to regenerate the isocyanate and liberate an amine which can initiate polymerization of the epoxy resin. Materials such as Monuron can also be used to accelerate the cure of dicyanodiamide so that it takes place at 120°C. 

Dicyanodiamide also reacts with several other functional groups, such as amidines,371 cyanamides,384 amines,385 guanidines,380 urea,387 cyanates,388 and ammonia,389 to form 1,3,5-triazines (cf. Houben-Weyl, Vol. E5, p 1382 ff Vol. E4, p 1072 ff). 

In 1909, 4-amino-6-methyl-l,3,5-triazin-2-ol was obtained by cyclization of (acetylcarbamimi-doyl)urca under basic conditions.443 Subsequently, several new processes based on acylated dicyanodiamides were developed.444-447,449 Thus, when acyldicyanodiamides 1 are heated to reflux in 2-ethoxyethanol, 4-amino-1,3,5-triazin-2-ols 2 are obtained in crude yields of 60 to 100%.444,445 Catalytic amounts of amine salts significantly accelerate this reaction. After selective acid hydrolysis of acyldicyanodiamides, (acylcarbamimidoyl)ureas 3 are obtained which can also be cyclized to the 1,3,5-triazines 2. These reactions are carried out in excess sodium hydroxide solution and provide the triazines in 90 to 99% yield.443,444,446 447 Cyclization of 1-acylbiurets 4, prepared by acid hydrolysis of (acylcarbamimidoyl)ureas 3, is effected by treatment with potassium hydroxide solution.444,448 While the benzoyl derivative 3 (R = Ph) yields the corresponding l,3,5-triazine-2,4-diol 5 (R = Ph) in quantitative yield, the acetyl derivative 3 (R = Me) cyclizes only partially to the corresponding triazinediol 5 (R = Me).448... 

Adding ammonia derivatives to cyanamide leads to guanidines. Salts of unsubstituted guanidine are obtained by melting dicyanodiamide with ammonium salts, e.g., with ammonium nitrate.43 Amines react smoothly with cyan-amide only if presented as hydrochlorides the components are boiled in anhydrous ethanol under reflux.44 This process fails with too feebly basic amines, e.g., with nitroanilines however, even in such cases almost quantitative yields of guanidines can be obtained by melting the amine with an excess of cyanamide and treating the product with an excess of concentrated hydrochloric acid.45... 

Discuss the chemistry of epoxy resins based on diglycidyl ethers of bisphenol A, their preparations, and crosslinking reactions with amines, dianhydrides, and dicyanodiamide. 

These prepolymers, which have been called ethoxylenes, are now called epoxy resins. Castan [41 crosslinked these polyethers by heating them with phthalic anhydride. Dicyanodiamide and ditolylguanidine were also used as crosslinking agents, and patents were granted for the use of amines and reaction products of dimerized fatty acids and aliphatic polyamines (Versamids) [5]. 

---