The Effect Of Dye Concentration And Polyol On The Performance Of Reactive Dye Solution Inkjet Printing

The aggregation behavior of dye molecules becomes a more common phenomenon because of the molecular interaction,especially highly concentrated reactive dye ink.And the aggregates have a crucial influence on the properties of ink.Meanwhile,the viscosity and surface tension of the solutions are also important factors determining the properties of the ink.And the quality of ink determines the quality of digital printing products.Therefore,this paper studied three kinds of reactive dyes: C.I.Reactive Orange 13(O-13),C.I.Reactive Red 24:1(R-24:1),and C.I.Reactive Red 218(R-218),the effect of dye concentration on the molecular aggregation,viscosity and surface tension of the dye solution was studied by combining the UV-Vis spectrophotometry and the curve deconvolution Gaussian peak;on this basis,the effects of three common organic solvents of ethylene glycol,1,3-propanediol and 1,4-butanediol on the inkjet printing performance of the dye solution were studied.The experimental results show that the dye molecules in the solution aggregate with the increase of dye concentration.The structure of the dye also has a certain effect on the degree of aggregation.since the non-conjugated part of Active Orange 13 is at the ? position of the naphthalene ring,the non-conjugated parts of Reactive Red 24:1 and Reactive Red 218 are both at the ? position of the naphthalene ring,resulting in the strongest aggregation of active Orange 13;however,because the conjugated part of Reactive Red 218 has one more benzene ring than Reactive Red 24:1,its solubility is relatively poor and its aggregation is relatively large.For the viscosity,the distance between the dye molecules is shortened due to the increased concentration,and the internal friction between the molecules is increased,which increases the viscosity of the solution.Among them,Reactive Red 218 has the largest relative molecular mass,resulting in the highest viscosity;Reactive Orange 13 has the smallest relative molecular mass and the lowest viscosity.For surface tension,the concentration increases and the surface tension decreases,which was related to the position and hydrophobicity of the water-soluble groups on the dye molecule.It is difficult for Reactive Orange 13 to form a two-phase structure at the gas-liquid interface because the water-soluble groups were evenly distributed on both sides of the molecule.The hydrophobic groups of Reactive Red 218 and Reactive Red 24:1 are located on one side of the molecule,but Reactive Red 218 was more hydrophobic than Reactive Red 24:1,and has a stronger adsorption capacity at the gas-liquid interface.As a result,the decrease of surface tension of Reactive Orange 13 was the smallest and that of Reactive Red 218 was the largest.Polyols of different contents were added into the dye solution with high concentration,dye molecules dis-aggregate,solution viscosity increases,and stability and surface tension decrease.As the mass fraction of the polyol increases,the dis-aggregation ability of the dye molecules increases,the viscosity of the solution increases,and the surface tension becomes smaller.The droplet morphology of the solution is affected by the viscosity and surface tension.When the viscosity increases and the surface tension decreases,the droplet will form small satellite droplets and the breaking speed will slow down.The K/S value of the inkjet printing patch is affected by the alcoholysis of the dye.When the polyol is added,the K/S value decreases.With the increase of polyol content,alcoholysis strengthens,and the decrease of K/S value increases.