The Study On Dispersion And Stability Of Organic Pigments

Water-based pigment ink is an environmentally friendly and non-polluting printing supplies,which has the very broad market prospect.The dispersion stability of organic pigments in aqueous systems is the key to the development of water-based pigment inks.In our research,the edible organic pigment(C.I.Pigment Blue 78)is the main research object,and the influence of grinding conditions on the pigment dispersibility was discussed.Besides,the effect of the kinds and amount of dispersant,the amount of thickener,the system pH and temperature changes and other factors on the dispersion stability of the pigment was also studied.We prepared a pigment paste with an average particle size of about 300 nm and studied the properties of the paste after it was formulated into an ink.During my master study,the achievements are summarized as follows:Firstly,the pigment grinding process was studied.When the speed was4000-4100r/min,the grinding time was 60 min,the mass ratio of grinding media to pigment paste is 2,the dispersion effect of pigment is the best,and the average particle size of pigment can be milled to 296 nm.Secondly,the dispersion and stability of pigments were discussed.For anionic dispersion,when the mass ratio of pigment / dispersant is 5-7.5,the specific absorbance of pigment paste was the highest,and the dispersion stability was the best.Among them,KD24 had the highest dispersion stability and the absorbency ratio was 79.6%.In addition,for polymer dispersant,when the mass ratio of pigment / dispersant was 1.5,the dispersion stability was the best.Among them,KD6 had the best dispersion stability and the absorbency ratio was 83.9%.Additionally,thickener PVP-K30 in the pigment content of1/10 to 1/12,the pigment has the best dispersion stability.Besides,the p H of the system also has some influence on the dispersion stability of the pigment.For the anionic dispersant KD24,the dispersion stability of the pigment pasteis the best when the p H is about 9.Overall,polymer dispersants have better temperature resistance than anionic dispersants.Where,the polymer dispersant KD6 was the best temperature resistance.After aging test,its particle size change smallest with an increase of only 9.2 nm.However,the anionic dispersant SDS has the worst temperature resistance and the largest particle size change with 30.3nm.Finally,we discuss the effects of resin,glycerol and diethylene glycol on the viscosity and surface tension properties of the ink.We demonstrate that the viscosity of the ink was increased,with the increase of the amount of the resin,glycerol and / or diethylene glycol.Among them,glycerin makes the viscosity of ink increased most obviously.Besides,they can make the surface tension of the ink slightly decreased with the small magnitude.