Study On Synthsis And Property Of Polyurethane-acrylate Hybrid Emulsion

Water-based ink has been paid more attention as the continuous improvement of individual environmental awareness and the high requirements to the printing quality recently.However,the printing adaptability problems of water-based ink on flexible packaging film are hardly to be addressed such as slow drying rate,poor adhesion etc,which seriously restrict the application of ink to food,medicine and health fields.To integrate the respective virtues of polyurethane and polyacrylate,the preparation of polyurethane(PU)dispersion and polyurethane-acrylate(PUA)hybrid emulsion that were used into primary ink,was studied and the influence on water-based ink was also estimated.Polyurethane dispersions(WPU)and double emulsification polyurethane dispersions(HPU)were prepared by self-emulsification method with polypropylene glycol(PPG),polyethylene glycol(PEG),poly-1,4-butylene adipate glycol(PBA),isophorone diisocyanate(IPDI),dimethylol propionic acid(DMPA)and butanediol(BDO),respectively.The results indicated that the particle size of WPU is less than 100 nm with 5wt% DMPA and the surface tension of polyurethane dispersion that modifed withγ-aminopropyltriethoxysilane(KH550)was obviously decreased from 36.42 mN/m to35.43 mN/m.As the solid content of high-solid polyurethane(HPU)dispersion in the range of 30 % and 40 %,HPU dispersion showed Newton fluid behavior while it exhibited pseudoplastic fluid characteristics when the solid content in the range of 40 % and 50 %.WPU with PBA(Mn=2000 Da)is easier than that with PPG(Mn=2000 Da)to prepare HPU dispersion.PUA-Ⅰ and PUA-Ⅱ series emulsions were synthesized via emulsification method and monomer dilution method,respectively.The influence of synthesis process,ratio of PU/PA,dosage of emulsifier and molecular weight of PPG on emulsion particle size and distribution,water resistance and contact angle,rheological property,drying rate,adhesion were investigated.It was found that the synergistic effect between DMPA and emulsifier is superimposed to reduce the emulsion particle size.When the ratio of PU/PA is 90/10,the contact angle and water absorption reached the optimum value as 72.1° and 10.2 %,respectively.The drying rate and thermostability of emulsions were excellent as the molecular weight of PPG is 2000 Da.When the addition of emulsifier is 2 wt% of monomers,PUA-I emulsions approached to the characteristics of Newton fluid while theyexhibited pseudoplastic fluid behavior as the dosage of emulsifier is 3 wt% or 4 wt% of monomers.Besides,the adhesion of PUA-I emulsions on PVC and PA films is better than that on BOPP film.Stable primary inks were prepared via the mixture of dispersion(or hybrid emulsion)and pastes and the printing adaptability of based inks on flexible packaging film were investigated.The results show that the rheological behavior of primary inks was in accordance with PUA-II-e emulsion when the mixture ratio of PUA-II-e emulsion and paste is 1:1(EP-5)and 2:1(EP-6).Besides,EP-5 exhibted fastest drying rate and the adhesion of based inks on PVC and PET films is excellent but that on BOPP film is poor.