Synthesis And Properties Of Hydroxylated Tung Oils Based Cationic Polyurethane Dispersion

Cationic polyurethane dispersion (CPUD) has been used in coatings, adhesives,textiles and paper due to its unique properties. The common CPUD, however, haspoor performance in heat resistance, water resistance and solvent resistance which arelimiting its wider application. Therefore, it is very necessary to introduce thecrosslinked structure or hydrophobic segment. In all of existing methods, vegetableoil modified CPUD has become one of the most potential methods because of the lowprice, hydrophobic properties and double bonds in vegetable oils. Among them, tungoil is China’s specialty and has three conjugated double bonds. Throughhydroxylation, the tung oil structure can be introduced to CPUD, forming thehydoxylated tung oil (HTO) based cationic polyurethane dispersion (HTO-CPUD).The performance of such modified CPUD is expected to be greatly improved.In this thesis, HTO-CPUD was synthesized based on HTO, N-methyldiethylamine (MDEA), and different polyether/polyester polyols and isocyanates.FTIR, NMR, DSC, DMA, laser particle size analyzer and TG were used tocharacterize its properties, respectively. The effect of diisocyanate, HTO and polyolstypes, preparation ways, MDEA content, neutralizer etc was also investigated. Themain results of the thesis are as follows:1. The stability of HTO-CPUD was mainly influenced by the content of MDEAand the degree of neutralization. The dispersion can be stable when the content ofMDEA was more than9%in total weight and the degree of neutralization was above85%.2. The particle size of HTO-CPUD was between8-71nm and it can be stable inacidic medium. Comparison with common CPUD, HTO-CPUD has much betterexcellent water resistance, solvent resistance and heat resistance. The mechanicalproperties of HTO-CPUD can also be enhanced with increasing the content of HTOand crosslinking density.3. The effects of different isocyanate, MDEA and soft segments on properties ofHTO-CPUD were very obvious. Compared to HTO-CPUD prepared by IPDI, HTO-CPUD prepared by HMDI exhibited smaller particle size and higher thermalstability. The thermal stability of HTO by alcoholysis was better than HTO byaminolysis; the particle size of HTO-CPUD with polyester polyols was larger thanHTO-CPUD polyether polyols.4. The studies on heat treatment to HTO-CPUD showed that the mechanicalproperties can be controlled and adjusted by different heat treatments. Withincreasing heat treatment temperature, the mechanical properties were improvedsignificantly, wherein the breaking strength increased from3.4MPa to34.9MPa.These changes are associated with further reaction of the conjugated double bondsand strengthening of intermolecular molecular interactions.Based on the above characteristics, HTO-CPUD is expected to be used inwater-based coatings and adhesives with high performance.