Synthesis Of Silocon-oxygen Cardanol And Study On Its Modified Amine Expoxy Curing Agent

The cardanol, a cashew nut shell liquid extract is bio-renewable resources; its uniquemolecular structure endows cardanol with a variety of chemical properties, which can beapplied extensively to chemical industry and other realms; especially utilized in the fieldof epoxy reisn, acting as a modified epoxy-amine curing agent, thus making a significantbreakthrough in preparing cardanol amine. Cardanol amine has excellent corrosionresistance, and heat resistance, but it presents deficiency on account of its low brittleness,resistance to high and low temperatures and weather resistance, hence fails to meetdemanding requirements.Silicone, equipped with outstanding heat resistance, flexibility, weather resistance andlower surface tension etc., can serve to enhance the performances when siloxane group isintroduced to the former system.This thesis concentrates on preparing cardanol acetate by using purified cardanolwith acetic anhydride under certain circumstances, which effectively protects the phenolichydroxyl group in case of side reactions and poisoning catalysts in the latter reactions.Then innovative the silicone is grafted to the cardanol compound through thehydrosilylation reaction of unsaturated bond on the long side chain of cardanol acetateand hydrogen siloxane (heptamethyltrisiloxane), and siloxane cardanol is obtained afterhydrolysis to anti-protect. Then, silicon-containing cardanol amine, as epoxy curing agent,can be generated in light of Mannich reaction by siloxane cardanol, formaldehyde, anddiethylene triamine, and the curing agent performances are therefrom tested andcompared. The specific researches and conclusions are as follows:(1)Synthesis of cardanol acetate: it was formed by esterification of the purifiedcardanol and acetic anhydride under the certain conditions, and the yield was determinedby the gravimetric method; the experiments indicate that the climax yield is95.67%whenthe molar ratio of acetic anhydride and cardanol is1.2:1, the reaction temperature is130℃, and the reaction lastsabout3.5hours without the presence of catalyst.Correspondently, the product is primrose yellow clear liquid. (2)Preparation of heptamethyltrisiloxane cardanol acetate: it was obtained throughhydrosilylation of the prepared cardanol acetate and hydrogen-containing end-cappingheptamethyltrisiloxane under certain conditions. Furthermore, the iodine value ofreactants and products, infrared spectroscopy and mass spectrometry were measured tocharacterize the optimal reaction conditions. The results demonstrate that the feeding ofthe reaction is dripping heptamethyltrisiloxane when titanium cardanol ester and Karstedtcatalyst are heated to near the reaction temperature by bulk polymerization, and the yieldhits the peak, approxiamately80%when the reaction temperature is130℃, the reactionlasts6to8hours, the catalyst is added in an amount of silicone quality30ppm, and themolar ratio of raw titanium cardanol ester and heptamethyltrisiloxane is1.3:1.(3)Preparation of heptamethyltrisiloxane cardanol: hydrolysis test conducted on theheptamethylsilicone cardanol acetate by using hydrochloric acid solution, NaOH solution,ammonium acetate solution respectively, in different concentrations and reactiontemperatures. And the optimal hydrolysis conditions were determined through infraredanalysis and mass spectrometry testing. The results illuminate that the higher rate ofhydrolysis, approximately70%, when1mol/L hydrochloric acid solution is added twicethe amount reactants, the reaction temperature is about100℃, and the reaction lasts about6hours.(4)Preparation of silicon-containing cardanol amine: silicon-containing cardanolcuring agent was obtained by Mannich reaction of the heptamethyltrisiloxane cardanol,paraformaldehyde and diethylene triamine and the process is that phenol and amine wereheated to60℃to70℃, and paraformaldehyde was added batchwise. Then it underwentthe following reaction for2hours at80℃, successively for1hour at110℃. Eventually,the byproducts of water and some of the free amines were removed by distillation underreduced pressure at105to110℃. It’s found that the product acquires suitable amine valueand viscosity when n (phenol): n (amine): n(aldehyde)=1:1.8:1.5. Moreover, incomparison with the common cardanol amine, the performance of the modifiedcounterpart attains the increase in flexibility as1mm of its cured paint film with hardnesskeeping unchanged as3H overall, tensile and flexural properties slightly augmented and its resistance to weather intensified while it tends to be inferior in adhesion. What’s more,the rate of residue is24.8%at600℃, which is more than ordinarycardanolic amine as16.4%.