Synthesis And The Fixative Performance Of Waterborne Polyurethane Modified With Hydroxypropy Silicone Oil

Waterborne polyurethane(WPU) as textile auxiliary has the advantages of non-formaldehyde, pollution-free and non-toxic. In recent years, with the international competition gradually becoming fierce for textiles, the environmentally-friendly textile has been more needed. Further, the safety of textiles has been attached importance at home and abroad, which provides a good opportunity for the development of WPU textile auxiliaries.WPU as the fixing agent, the fastness to rubbing and the drying rate should also be considered. In order to prevent the shedding of WPU film, the good water resistance, adhesion and heat resistance properties should be required. The-NCO in the polymer chain can react with fabric of-NH2,-OH, which is a basic principle for WPU fixation. The content of-NCO in emulsion could be evaluated by the R value. Besides, the heat resistance and water resistance of the WPU fixing agent film can be affected by the value of R. In addition, the factors which can affect the film water resistance are the content of hydrophilic chain extender and neutralization degree. However, the key for improving the fabric rubbing fastness of the fabric is to improve the resistance to water. Furthermore, different synthetic approaches mean that the WPU fixative polymer chain structure is also different, which could lead to different performance of the WPU fixative. The performance of a series of waterborne polyurethane which had been synthesized by different methods, polyols with different the molecular weight, different content hydrophilic chain extender, neutralization degree and different R value had been studies. The better synthesis process for WPU fixing agent was found.When the R value is 1.1, the molecular weight of polyols 1000, the content of DMPA 5.5%, and the neutralization degree 100%, the ionic group in soft segment of WPU caking property, resistance to water and the drying rate is found better. The emulsion is transparent and stable. The viscosity of emulsion, evaporation rate, maximum water absorption of the WPU emulsion are 8.39%, 0.87, 142MPa?s, respectively. The bonding strength, tensile strength and elongation at break are 0.69 MPa, 4.18 MPa, 406.31%, respectively. In addition, when the content of the WPU fixing agent in emulsion is 50 g/L, the dry/wet rubbing fastness of the fabric was been improved.The development of the WPU fixing agent is limited by the disadvantages of the slow drying rate and the poor resistance to water. Because hydroxypropyl silicone oil has the low surface energy, it is used to improve the performance of WPU, which can make the WPU to have good resistance to water, and can make the emulsion drying rate increase. Furthermore, the rotary flexibility of Si-O bond can improve the fabric flexibility. Therefore, in the thesis, the hydroxypropyl silicone oil was introduced by the method of chemical copolymerization, and the siloxane modified WPU fixing agent was obtained.In conclusion, when the amount of hydroxypropyl silicone oil is 3%, the emulsion viscosity and bibulous rate are 230 MPa?s and 3.1%, respectively; the bonding strength, tensile strength and elongation at break are 0.60 MPa, 18.36 MPa, 598%, respectively. Moreover, when the hydroxypropyl silicone oil content reached 5%, the fabric dry/wet rubbing achieved the best performance. Compared with the non-finishing fabric, wet rubbing fastness of finishing fabric increased 2-3 grade.