UV-curable Waterborne Polyurethane:preparation And Application In Electrostatic Flocking

Acrylate electrostatic flocking adhesive has been widely used on the market due to its advantages such as strong adhesive strength of fibers, easy obtainment of the raw material, simple operation and low cost. However the adhesives that are currently in use mostly exist the problems of high baking temperature and excessive energy consumption.Meanwhile the cross-linking monomer of most products is N-hydroxymethyl acrylamide,and after cross-linking it will slowly releases formaldehyde, which has certain harm on the human body.This paper intends to develop a new kind of energy saving and environmental protection electrostatic flocking adhesive,which is synthesized by using multi cyanate ester, polyol,hydrophilic chain extender, end capping agent and the neutralizing agent as the main raw material.The whole content of this paper can be divided into the following three parts:1.Study the influence of various factors on the properties of aqueous polyurethane emulsion.2.Study the performance of different kinds UV curable polyurethane.3.Study the application of UV curable waterborne polyurethane on electrostatic flocking.In the first part, the influence of various factors on the properties of the waterborne polyurethane emulsion is discussed by experiments.The results indicate that the performance of waterborne polyurethane can achieve the expected effect by using IPDI,polyether polyol as raw material;the emulsion becomes blue and transparent liquid,and increases stability with the increase of the content of hydrophilic group by using DMPA as hydrophilic chain extender;when terminat-ing with hydroxyethyl acrylate,the methoxyphenol is chosen as inhibitor preferentially,and it has small impact on the appearance of the emulsion;TEA is selected as neutral agent preferentially;the emulsion changes from blue light into the milky liquid with the increase of the solid content of the emulsion.In the second part, FT-IR,TG,and DSC are employed to investigate the structures and thermal properties of the electrostatic flocking adhesive films and analyze the influence of various factors on the properties of water borne polyurethane and the curing speed.The results show that when using PTMG as polyol,the emulsion is blue and transparent,and the particle size is smaller than PPG,and has stable storage.The mechanical properties of the cured film is better than polyurethane of PPG,and when the molecular weight of the PTMG is 2000, the stress of curing film is 3.71 MPa and the strain is 343.33%;When the content of DMPA is 4.69%, the particle size of emulsion issmall,and has stable storage, and the performance of the cured film is excellent; when the dosage of methoxy-phenol is 0.1%,it has good effect of inhibition of polymerization and emulsion stability;when TEA is used as neutralizing agent, and the degree is 90%, the particle size of emulsion is small,and has stable storage;compared to the HEA, TMPDA has good performance as the capping agent,and can increase the cross-linking density of the cured film and improve the mechanical properties of the curing film;the maximum content of solid content of the emulsion can reach 40%,and it is hard to emulsify beyond 40 %;when using TMPDA as diluting agent and the dosage is 8%, the mechanical properties of curing film are the best;waterborne polyurethane curing film has good acid resistance and solvent resistance,but bad alkali resistance;when the dosage is 3%, with TPO as initiating agent, UV curing speed of the system is fastest, and the curing speed of other light triggered agent is almost same.In the third part,the effects of upper adhesive rate,pre drying time and the UV curing time on the performance of electrostatic flocking are measured by using home-made UV curable waterborne polyurethane.The results show that the best application process is that the upper adhesive rate is 300-350g/m2,pre drying time is 8 min at 80 centigrade, and the curing time is15s;at the optimum conditions of first step,the performance of flocking fabric is better with GMA as diluent,which the dry and wet rubbing fastness reach grade 5 and the wear resistance reaches15000 times;the performance of flocking fabric is better with TMPDA as blocking agent which the dry rubbing fastness reaches grade 5,the wet rubbing fastness reaches grade 4-5,the wear resistance reaches 13000 times.