Synthesis And Properties Of Vegetable Oil Modified Cationic Waterborne Polyurethane

Since the21st century, along with the improvement of the consciousness of people’s environmental protection and various environmental laws and regulations,the negative effects caused by the organic solvent contained in the solvent-based polyurethane are becoming more and more obvious. Therefore, the development of waterborne polyurethane (WPU) which has many advantages such as non-toxic、pollution-free and low organic volatile content etc, has a very important significance. In the process of polyurethane prepolymer formation, small molecule chain extender with the performance of hydrophilic is added, at the end of the reaction, the neutralizer and salt-forming agent are added, after emulsion with water, the waterborne polyurethane emulsion is prepared. This is the generic self-emulsification method.The general principle of self-emulsification method is that the hydrophilic group is introduced into the side chain or the main chain of the polyurethane molecule, thus without adding an emulsifier, the polyurethane pre-polymer can be dispersed in water, small emulsion particle size、excellent performance of the film and long-term stability can be achieved. Another method of preparing water-borne polyurethane is to add the emulsifier in the process of emulsification, forcibly dispersed using the high-speed stirring method,making the particle size of the emulsion larger and the stability poorer. The solid content can reach more than50%, the external emulsification method is not commonly used.The waterborne polyurethane now widely used in industries such as leather finishing agent、wood lacquer、 adhesive、coating etc, has begun to replace solvent-based polyurethane gradually. In these applications, the anionic waterborne polyurethane has been widely used,many researches in this area have been reported,while the cationic waterborne polyurethane research is less.This is mainly because in the preparation process of cationic aqueous polyurethane, the process of quaternary ammonium salt of the pre-polymer is complex, in addition, the cost is quite high,the stability of the emulsion products are worse than the anionic waterborne polyurethane. Compared with anionic waterborne polyurethane,cationic waterborne polyurethane has its unique properties, and has great application value,the development of novel cationic waterborne polyurethane has important research significance. With increasing depletion of oil resources and higher prices of petrochemical products, research about renewable energy has been imperative. Production of polyurethane with biomass polyols instead of petrochemical raw materials is a viable trend.The biomass polyol mainly includes vegetable oil、plant cellulose、lignin etc,it has been reported that, compared to petroleum polyols, biomass polyol reduced energy consumption to around23%, non-renewable energy consumption was reducesd by61%, the use of lkg of biomass polyurethane let off less1.2kg of carbon dioxide emissions into the atmosphere. This paper mainly discussed the vegetable oil-modified cationic waterbrne polyurethane.A series of waterborne polyurethane emulsions modified by KESO were synthesized using the method of three steps, adopting polyether diols(N-210)、 isophorone diisocyanate(IPDI)、N-methyl diethanolamine (MDEA)-、 diethylene glycol(DEG) as the principal raw materials. The influence of the amount of KESO on the performance of polyurethane emulsion and film were studied by emulsion particle size、infrared spectrum、 mechanical propertie、s hardness、thermal properties、water resistance、acid and alkali resistance etc. tests. The results showed that, stable cationic waterborne polyurethane emulsion can be synthesized when the mass content of KESO belows20.4%; with the increase of the content of KESO, the emulsion particle size became larger; because the KESO contains three hydroxyl groups, the polyurethane molecular structure turned into three-dimensional net-like structure, the mechanical properties of the film were improved, and thermal stability can also be improved to some extent.The cationic waterborne polyurethane modified by caster oil were synthesised by caster oil(C.O.)s isophorone diisocyanate(IPDI)、 N-methyl diethanolamine (MDEA)、diethylene glycol(DEG)、polyether diols(N-210)、 poly-1,4-butylene adipate glycol(PBA) trimethylolpropane(TMP) etc. The influence of the amount of C.O on the performance of polyurethane such as emulsion stability、water resistance、 thermal properties、hardness and mechanical properties were studied by infrared spectrum、water absorption、 thermogravimetric analysis、 rocker hardness、tensile experiment etc. tests.The test results indicated that, with the addition of C.O, the polyurethane emulsion particle size became larger and stability of polyurethane emulsions were reduced; while tensile strength and thermal stability of materials were improved, and can make the films had good elongation at break on the premise of good tensile strength. When the c.o content was up to8.3%, the tensile strength of the film can reach 20.1Mpa, the thermal stability was improved. The water absorption of the polyurethane films can reduce to about1%at most.Using the polyester type cationic waterborne polyurethane and the polyether type cationic waterborne polyurethane,adding a certain percentage of additives,the cationic water-based adhesives can be made, then compared with anionic waterborne polyurethane adhesives.The results showed,each performance of polyester adhesives was better than that of polyether adhesives, and the performance was very close to the anionic waterborne polyurethane. The T-type peeling strength can reach up to3.21N/mm,the softening point can reach65℃, the water absorption of72hours was9.8%.