Preparation And Properties Of Humic Acid Modified Waterborne Polyurethane Materials

With the progress of science and the development of technology,environmental consciousness has been increased day by day in people’s mind.Waterborne polyurethane(WPU)gradually comes into the sight of people instead of traditional solvent-based polyurethane with organic solvent as dispersion medium.Waterborne polyurethane(WPU)uses water instead of organic solvent based on keeping the excellent properties of solvent-based polyurethane and makes itself has some other advantages such as environmentally friendly,non-poisonous,nonflammable,low-cost and so on.Waterborne polyurethane(WPU)and waterborne acrylics(WPA)can compound to form waterborne polyurethane-acrylics which possess both advantages of two resins.UV-curing coating is a new type of green environmentally friendly coating.It has become one of the hot topics in the current research and has great prospect of development because of its advantages for small volatilization,little pollution,fast curing speed,less material consumption,etc.Humic acid(HA),a kind of natural organic polymer decomposed and synthesized by animal and plant residues under the chemical action of microorganisms and globe,exists widely in soil,lake,river,ocean,peat,lignite,weathered coal.Humic acid contains multiple functional groups such as hydroxyl,carboxyl,quinonyl,amidogen and etc.Because of these active groups,humic acid possess hydrophily,interfacial activity,cation exchange capacity,complexing action and adsorption-dispersion capacity and have wide applications in environment protection,oil extraction,agroforestry,medicine,chemical industry,battery industry,etc.This article mainly uses humic acid to modify waterborne polyurethane.The main work is divided into the following five system:(1)The first system adopted base-dissolving acidification method to extract humic acid from coals.Coals were pretreated before the extraction.Waterborne polyurethane modified by humic acid(HA-WPU)was synthesized with NJ-220(polyether polyol),DMPA(hydrophilic monomer),IPDI(isocyanate),HA(modifyingagent),TEA(neutralizer),ethane diamine(chain extender).Physical properties of emulsions such as apparent viscosity and surface tension were analysized.Mechanical properties,water resistance and thermostability of films were also analysized.When the content of HA was less than 0.08wt%,the emulsions all have good physical properties and storage stability.When the content of HA was 0.06wt%,films had the best mechanical properties and water resistance.The results show that HA extracted from coals can modify WPU effectively and improve the performance of WPU films.In addition,HA extraction is simply-operated and low-cost.Thus,it has a good application prospect.(2)The second system used polyether polyol NJ-220,hydrophilic monomer DMPA,isocyanate TDI instead of IPDI as raw materials to synthesis polyurethane.TDI type waterborne polyurethane modified with humic acid was synthesized with HA as modifying agent,TEA as neutralizer,ethane diamine as chain extender similarly.The formula of TDI type waterborne polyurethane was optimized.When the R value ratio was 2.3 and the content of DMPA was 8wt%,prepared waterborne polyurethane had good film-forming properties.Physical properties of emulsions such as apparent viscosity and surface tension were analysized.Mechanical properties,water resistance and thermostability of films were also analysized.When the content of HA was less than 0.08wt%,all the emulsions had good physical properties and storage stability.When the content of HA is 0.04wt%,films had the best mechanical properties and storage stability.Compared to the IPDI type waterborne polyurethane,the mechanical properties of films were improved while the physical properties of emulsions and water resistance got worse.(3)The third system used mixed polyether polyols NJ-220 and NJ-330 based on the best content of HA 0.06wt% in the first system.Waterborne polyurethane modified with HA was synthesized by changing the ratio of the two polyether polyols.Mechanical properties and water resistance of the films were mainly studied.When the ratio of NJ-220 and NJ-330 equaled 3:7,the mechanical properties and waterresistance of films reached the best.It also showed better performance compared with using NJ-220 or NJ-330 seperately.(4)The fourth system used HEMA to block the polyurethane chain with HA as modifier based on the first system.Reactive diluent BA and TPGDA was added to the system to modify the waterborne polyurethane.UV-curing waterborne polyurethane-acrylate was prepared by finally adding photoinitiator 1173 for UV-curing.The physical properties of emulsions were studied.Fracture surface morphology,mechanical properties,water resistance and thermostability of the films were also studied.When the content of HA is 0.04wt%,films had the best mechanical properties and water resistance.Compared to the non-UV-curing system,water resistance and thermostabilty were improved obviously.The results show that HA can improve the performance of UV-curable waterborne polyurethane and it has a good application prospect in the field of UV-curable waterborne polyurethane coating.(5)The fifth system adopted HA and Si O2 to doubly modify UV-curing polyurethane-acrylate.The content of HA was the optimum value 0.04wt% in the fourth system.Silicon dioxide sol prepared by hydrolysis of TEOS was used to secondly modify UV-curing polyurethane-acrylate via silane coupling agent KH-560.The physical properties of emulsions were studied.Fracture surface morphology,mechanical properties,water resistance and thermostability of the films were also studied.When the addition amount of TEOS was 0.3wt%,mechanical properties and water resistance of films achieve the optimum.Thermostability of films was also improved.It has a good application prospect in the field of UV-curable waterborne polyurethane coating.