Synthesis And Properties Of Epoxy/Polyurethane Blocked Cationic Resins

Epoxy resins are widely used with great varieties.However,the unmodified epoxy resin has defects such as brittleness,easy to be cracked,and poor impact resistance etc.Polyurethane,on the other hand,has the characteristics of high flexibility and adhesive force.By using the method of copolymerization to combine the above two resins,the strengths of them can be complemented.Meanwhile,new polyurethane epoxy material with different properties can be obtained.(1)Synthesize polycaprolactone glycol(PCL-2000)and isophorone diisocyanate into polyurethane prepolymer and conduct chain extension polymerization utilizing polyurethane prepolymer,piperazine and epoxy resin.By controlling the material ratio of copolymer to adjust the molecule mass of synthetic resin and flexibility and make series linear multi-block macromolecular resin.The structure of the synthetic resin was characterized by infrared spectrometer(FI-TR),gel permeation chromatograph(GPC),amine value measurement and hydroxyl value measurement.And the effect material ratio has on resin structure parameters and thermal stability has been studied.The result showed that adjusting material ratio can control the molecule mass of synthetic resin,amine value and the size of active hydrogen value.(2)The synthetic resin was neutralized and hydrated to prepare a resin emulsion.To test the waterborne resin's particle size,zeta potentiometer was adopted.The effect material ratio has on resin water dispersibility was explored.The test results show that the waterborne resin particle size can be adjusted from 55.26 nm to 107.1 nm.Mixing waterborne resin with curing agent,and the cured sample was obtained after being baked.To test the performance of resin water's cured property,electronic stretching machine and dynamic mechanical analysis(DMA)were adopted.The effect material ratio has on resin water's cured property was explored.The test result showed that the tensile intensity of cured material,fracture elongation rate and Tg can be adjusted from 10.46 MPa to 22.14 MPa,628% to 190%,and 22.3 ? to 44.7 ? respectively.(3)After the synthetic resin and the blocked isocyanate curing agent were co-emulsified in a certain proportion,a cathodic electrodeposition coating was prepared.The effect material ratio has on electrophoretic fluid performance was discussed by analyzing the properties of cathodic electrophoretic fluid particle size obtained from block copolymer resin,conductivity,mechanical stability,pH value.The result showed that the conductivity of electrophoretic fluid can be adjusted from 1947 ?S/cm to 2627 ?S/cm.pH value can be adjusted from 4.49 to 5.60.The obtained emulsion particle size and its distribution were relatively small.The mechanical and storage stability were both up to standard.The effect material ratio has on film properties was studied by using a set of international methods to test the property of electrophoresis coating.The result showed that material ration can affect the properties such as thickness,hardness,glossiness,water,acid and alkali resistance etc.The result also showed that the overall film performance was at the peak when Rt(28)1.25,H%(28)30w%.