Study On Synthesis And Application Of Polyurethane Foaming Catalyst Bis(3-Dimethylaminopropyl) Isopropanolamine

Polyurethane is widely used in many fields.Amine is needed to promote the foaming process of polyurethane,and improve the application performance of the material.N,N-Bis(3-dimethylaminopropyl)isopropanolamine(BDMPAP)is an alcoholamine catalyst and also a tertiary amine catalyst.It can balance the gel reaction and the foaming reaction in the polyurethane foaming process,with low odor and excellent effects.One of the synthetic raw materials of BDMPAP is Bis[3-(dimethylamino)propyl]amine(BPA).From the perspective of green and safety,a new process for the synthesis of BPA by dehydration of alcohols and amines is proposed,which avoids the high hydrogen pressure and high toxicity of nitriles in the common hydrogenation process of nitriles and amines.In addition,propylene oxide is selected to react with BPA to obtain BDMPAP,which is simple,efficient,environment-friendly and avoids the production of inorganic salts in the reaction between halogenated hydrocarbons and BPA.First,a series of bimetallic nickel-based catalysts were prepared by the volumetric immersion method.Of all tested samples,In the reaction of dehydration of N,N-dimethyl-1,3-propanediamine and 3-(dimethylamino)-1-propanol to BPA,Ni(10%)-Sn(5%)/Al2O3 catalyst shows the excellent catalytic effect.After characterization and analysis of the catalyst,it is found that the NiSn alloy formed could provide more acid sites and facilitates the reaction.Secondly,the influence of various process factors on the synthesis of BPA was investigated,and the optimized process conditions were follows:the molar ratio of N,N-dimethyl-1,3-propanediamine and 3-(dimethylamino)-1-propanol is 1.2:1;the catalyst is Ni(10%)-Sn(5%)/Al2O3,catalyst dosage is 5%of the total mass of reaction raw materials;the reaction temperature is 180?;the hydrogen pressure is 0.5 MPa;the reaction time is 10 h.The conversion of 3-(dimethylamino)-1-propanol was 61.40%,and the reaction yield was 52.64%.The catalyst can still maintain a high reaction yield after repeated use for 5 times.By GC-MS,FT-IR,and NMR,the molecular structure of the product was determined to be consistent with the molecular structure of BPA.Third,the reaction conditions for the reaction of BPA and propylene oxide to obtain BDMPAP have been optimized:the molar ratio of propylene oxide and BPA is 0.95:1;catalyst is sodium hydroxide,catalyst dosage is 0.5%of the total mass of reaction raw materials;the single feeding amount of propylene oxide is 25%of the total;the reaction temperature is 120?.The conversion of BPA was 87.93%(theoretical maximum conversion rate is 95%),and the reaction yield was 83.21%.By GC-MS,FT-IR,and NMR,the molecular structure of the product was determined to be consistent with the molecular structure of BDMPAP.Finally,BDMPAP?BPA?BDMPAP synthetic crude products were applied to the preparation of polyurethane foam.It is found that when the dosage of BDMPAP is 0.5%,a better foaming effect could be achieved.The foam average pore diameter is about 380?m and the apparent density is 0.02853 g/cm3.The opening percentage is 32.5%,the foam structure is uniform and dense,and the resiliency is 17.5%.Meanwhile,the catalytic effect of BDMPAP synthetic crude product is roughly the same as that of BDMPAP,and there is no need to further separate by-products by distillation.