Study On Modification Of Polyurea Material

Polyurea is a new type of non-solvent,non-polluting green polymer material developed by foreign companies in recent years,following low?non?pollution coatings,such as high solid coatings,water-based coatings,radiation curing coatings,powder coatings and so on.The difference between polyurethane urea and polyurea is that the amine component?R component?can contain polyether polyol and amino resin.The NCO group of the isocyanate component?component A?in the polyurethane/polyurea can be mixed and modified with a variety of resins,such as polyester,polyether,epoxy,silicone,acrylic,etc.,tomeetdifferentapplicationrequirements.Itcanobtain polyurethane/polyurea materials with excellent performance,wide range of uses and high cost performance to meet the diversified requirements of the national economy.The basic formulation of this project is:A component:NCO prepolymer 1,R component:amine-terminatedpolyether,polyetherpolyol,4,4'-bis-s-butylamino diphenylmethane,prepared polyurethane/Polyurea as a blank coating?HPU1?.On the basic formulation,HPU1 was modified with phenolic resin,epoxy resin,and silicone resin,respectively.The modified product was characterized by Fourier transform infrared spectroscopy?FTIR?,and then the coating gel time,surface dry time,mechanical properties,strong acid resistance?25%HCl,45%H₂SO₄,75%H₃PO₄?,and strong resistance,alkalinity?45%NaOH?,heat resistance,damping properties,and storage modulus E'and loss factor tan?master curves of the coating at a constant temperature of the coating were investigated.The phenolic resin was used as a modifier,and different amounts of phenolic resin were introduced into the R component to prepare phenolic resin modified polyurethane/polyurea coatings,which were respectively numbered as HPU2,HPU3,HPU4,and HPU5.The FTIR indicated that the phenolic resin had been successfully grafted into the polyurethane/polyurea molecular main chain,and then the coating was tested for its properties.The results show that when the content of phenolic resin in R component is about 50%,the comprehensive performance is better,the tensile strength is increased from 8.9MPa to 13.2MPa,the resistance to strong acidity is increased,the resistance to strong alkalinity is slightly poor,and the glass transition temperature?T_g?Increase from 12.6°C to 106°C;increase the damping performance;and predict the change of storage modulus?E'?and loss factor?tan??with frequency at 20°C.E-51 bisphenol A type epoxy resin was used as a modifier,and first the amino-terminated polyether and diethyltoluenediamine?DETDA?were respectively modified to obtain epoxy-terminated modified polyether and Epoxy-modified DETDA.The FTIR-terminated epoxy-modified polyether and the terminal epoxy-modified DETDA were characterized.The results showed that the epoxy-terminated modified polyether and the terminal epoxy modified DETDA were the products synthesized by the experiment.Then,the epoxy-terminated modified polyether and the epoxy-terminated modified DETDA are respectively introduced into the R component of the basic formulation,and thenreactedwiththeA componenttoobtainanepoxyresin-modified polyurethane/polyurea coating,respectively,and for HPU6,HPU7,HPU8,and performance testing of the coating.The results show that the mechanical properties of the polyurethane/polyurea coating modified by epoxy resin are good;after being soaked by high concentration of strong acid solution,the coating surface of HPU7 and HPU8 is not damaged;the introduction of epoxy resin is strong against the coating,Then,the epoxy-terminated modified polyether and the epoxy-terminated modified DETDA are respectively introduced into the R component of the basic formulation,and then reacted with the A component to obtain an epoxy resin-modified polyurethane/polyurea coating,respectively.For HPU6,HPU7,HPU8,and performance testing of the coating.The results show that the mechanical properties of the polyurethane/polyurea coating modified by epoxy resin are good;after being soaked by high concentration of strong acid solution,the coating surface of HPU7 and HPU8 is not damaged;the introduction of epoxy resin is strong against the coating alkaline properties did not affect.According to the thermogravimetry chart,HPU7 has the highest initial decomposition temperature(T₁₀)of334.1?,and the temperature(T₅₀)at 50%weight loss is 400.5?.From the tan?-T spectrum,HPU8 has the highest T_g of 96?,to improve thermal performance.obtained from the tan?-T spectrum,the modified coating's damping temperature range is broadened,the tan?peak value is increased,and the damping performance is improved;The trend of coating E'and tan?in the frequency range of several millions of degrees at 40?is predicted to provide guidance for the practice.Hydroxy silicone oil and epoxy resin were used as modifiers.Firstly,hydroxy silicone oil was used to modify diphenylmethane diisocyanate?MDI50?to obtain end NCO prepolymer 2;epoxy resin was used to modify DETDA and obtain end Epoxy-based modification of DETDA.The modified product was characterized by FTIR.The results showed that the end NCO prepolymer 2 and the terminal epoxy group modified DETDA were synthesized as predicted by the experiment.Then,the NCO prepolymer 2 was introduced into the A component at different ratios.The terminal epoxy group modified DETDA was added to the R component at a fixed content,and the obtained coatings were respectively numbered as:HPU9,HPU10,HPU11,HPU12,then to test the performance of the coating.The results show that the mechanical properties of HPU9,HPU10,and HPU11 are good;HPU10 has the highest T₁₀0 and T₅₀,which are 330.1?and 410.5?,respectively,as measured by TGA.At the same time,the T_g is higher than that of the blank sample.The coating damping temperature range is wider than that of HPU1,and the peak value of tan?is also higher than that of HPU1.The damping performance is significantly improved.The storage modulus?E'?and loss factor?tan??of the coating at 20?are predicted.In summary,the three types of modification experiments have excellent mechanical properties,and the formulations with good resistance to strong acid,and heat-resistant formulas for HPU4 and HPU7.In terms of strong alkali properties,only the phenolic resin modified coatings are used.In terms of strong alkali properties,only the phenolic resin modified coating performs slightly poorer;the silicone resin and epoxy resin mixed modified coating has excellent heat resistance,HPU10 formula is better;The damping performance of the modified epoxy resin coating is better,HPU6 has a wider damping temperature range?12?⁹0??,the peak value increased to 0.8.