Preparation And Properties Of Solvent-free Epoxy Non-isocyanate Polyurethane Anticorrosive Coatings

With the development of economy and the increasing awareness of environmental protection,the traditional coating of epoxy resin cannot meet the demand of the market and industrial protection due to failure to balance both the performance and environmental requirements.Solvent-free coating of nonisocyanate polyurethane has the characteristics of environmental protection and safety because it do not use the poisonous organic solvents and isocyanate as the raw material.At the same time,it combines the advantages of epoxy resin and polyurethane,with excellent corrosion resistance and good adhesion.Therefore,this is a kind of environmental-friendly coatings and has a good application prospect in the field of anticorrosive coating.The main research contents in this work are as follows:(1)To find the suitable epoxy resin and curing agent,the preparation and performance tests of epoxy resin coating were carried out,which laid a foundation for the modification of epoxy resin coating.The curing properties of epoxy resin(E-44,E-51 and NPEF-170)and three amine-based curing agents(D-230,T-403 and aliphatic amine)were investigated.The prepared coating of epoxy resin has a solid content of more than 95%,adhesion of 0 level,hardness of H,and salt-spray resistance time of 168 h.(2)Based on the preparation of epoxy resin coatings,three different kinds of silicone(Dow Corning DC-3074,Chen Guang Z-1,dihydroxydiphenylsilane(DHDPS))were used as raw materials,coupled with epoxy resin,dibutyltin dilaurate(DBTDL)acted as catalysts.They were reacted with each other at high temperature,and then modified epoxy resin by the organic silicone was prepared.The effects of reaction conditions,the reaction temperature,reaction time and the organic silicon resin type on product property were discussed.The results showed that the fineness of product is 20 ～ 25 μm,solid content is more than 95%,surface drying time is 25 minutes,the appearance of coating is smooth,the hardness is 2 H,adhesion is 0 and the time of salt-spray resistance is 432 h under the conditions of E-51 epoxy resin as the resin matrix,12.5% Dow Corning DC – 3074 as modifying agent of epoxy resin and 0.5% DBTDL as the catalyst,reacted at 120 ℃ for 3 h.(3)Because the non-isocyanate polyurethane did not need toxic isocyanate as raw material,and also could improve the salt-spray resistance property,therefore,in this research,cyclocarbonate is prepared with epoxy resin and carbon dioxide as raw materials,tetrabutylammonium bromide(TBAB)as catalyst at high temperature and high pressure.And the product was characterized by FTIR,and the effect of reaction temperature,reaction pressure,reaction time and catalyst amount on the fractional conversion were discussed.The results showed that the fractional conversion reached 97.48% at temperature of 100 ℃,the pressure of 1.5 MPa,the reaction time of 4 h and the usage of TBAB of 1.5%.(4)On the basis of the preparation of cyclocarbonate,solvent-free epoxy non-isocyanate polyurethane were prepared with modified epoxy resin and cyclocarbonate as the resin substrate and polyetheramine D-230 as the curing agent substrate.The formulation of solvent-free nonisocyanate polyurethane anticorrosive coating was as follows: component A: the resin base material E-51 of 50%,talc powder of 10-12%,titanium dioxide of 5%,sericite of 4-6%,gaseous silica of 0.5-1%,diluent of 15-20%,antifoaming agent of 0.5-1.5%,dispersant of 0.5-2.0%,leveling agent of 0.4-0.6%.Component B: the curing agent D-230 of 96%,defoaming agent of 0.5～1.5%,dispersant of 0.5～2.0%,leveling agent of 0.4～0.6%.In process of manufacture,component A and component B were mixed according to the mass ratio of 4:1.The mixed coating could be dried at 80 ℃ for 20 min,and the appearance of coating is smooth.After curing at room temperature for seven days,the results showed that the hardness could reach 2H,the adhesion level was 0,and the salt-spray resistance time was more than 1500 h.The solvent-free nonisocyanate polyurethane anticorrosive coating had the advantages of simple preparation,easy construction,wide range of application,good salt-spray resistance and low VOC emission.It is an environmental-friendly coating.