Research On The Jetting Performance Of Reactive Dye Solutions

As one of the most important consumables for digital inkjet printing,the properties of inkjet printing ink directly decides the quality of printed products.Reactive dye inks are widely used in the dyeing of cotton fibers and other cellulose fibers due to their advantages such as complete chromatography and good wash fastness.In this paper,four different reactive dyes including C.I.Reactive Orange 13,C.I.Reactive Red 218,C.I.Reactive Yellow 95 and C.I.Reactive Blue 49 were selected.UV/Visible absorption spectra of different concentration dye and electrolyte solutions were tested.Dynamic surface tension and viscosity of different concentrations dye solutions were tested,and droplet patterns for the four dye solutions were observed.It is found that with the increase of dye concentration,the dyes with uniform distribution of water-soluble groups and without isolated hydrophobic structure do not have obvious aggregation.On the contrary,dyes with uneven distribution of water-soluble groups and isolated hydrophobic are significantly aggregated.The higher the concentration of the electrolyte,the more the degree of aggregation the dye molecules have.Various metal ions' abilities of promoting the aggregation of dye molecules were different.The ability of different kinds of metal ions to promote the aggregation of dye molecules is different.The metal ions with more charge numbers and stronger ability to combine with water molecules to form hydrated metal ions could result in more obvious aggregation of dye molecules.Dye concentration and structure can affect the dynamic surface tension of the solution.The greater the dye concentration of the same dye solution,the more the surface tension drops in the same time.Dye molecules which have isolated hydrophobic structure and unifarm water-soluble groups,easily reduce the surface tension of the solution.The viscosity of the solution is affected by the dye concentration and the molecular structure of the dye.The greater the dye concentration is,the greater the viscosity the solution has.The greater the number of hydrogen bonds between dye molecules and the obvious aggregation of dye molecules,the greater the viscosity of the solution.The viscosity of the dye solution affects the location and shape of the droplets breaking at the nozzle.The dynamic surface tension affects the number of droplets formed during the ejection process.The greater the dynamic surface tension is,the greater the number of droplets is formed during the ejection.