Study On The Stability And Rheology Of Water-based Ceramic Ink

Ink-jet printing is the mainstream technology for printing images onto ceramics without patterning or etching processes.The key to this technology is the performance of the ceramic ink.In particular,the ink is required to have good suspension stability,to avoid the occurrence of particle agglomeration and precipitation and blockage of the nozzle.Currently,organic solvents with low surface tension and dielectric constant help to improve the dispersion and suspension stability of ceramic inks.However,organic solvents are volatile.There is a risk of combustion and toxicity in production.Therefore,the market is eagerly seeking highly stable water-based ceramic inks.However,there are relatively few water-soluble dispersants and stabilizers.It is difficult to obtain a water-based ceramic ink with good stability and spreadability expected.According to the Stocks law,increasing the viscosity of water-based ink helps reduce the sedimentation of ceramic powders.In order to maintain the stability of the water-based ceramic ink and have good inkjet printing performance,this paper proposes to add a guar gum solution with high shear thinning performance to the water-based ink.On the one hand,the macromolecules of guar gum can be used to make the ink have a high viscosity in a static state,so as to obtain high suspension stability of the ink.On the other hand,with the shear thinning effect of guar gum solution,the ink in the sprayed state has a very low viscosity,which can meet the spraying requirements.Experimental results show that: For vanadium blue ink,when the solid content of the colorant is 30wt%,the dispersant chooses super dispersant C-08 and the amount is 1%,the ink viscosity is 19.5m Pa·s,and the ink does not precipitate for 12h;For the scarlet ink,when the colorant content is 25wt%,the dispersant selects the carboxylic acid-containing polyelectrolyte dispersant CE-64 and the amount is 0.4%,the ink viscosity is 18.53 m Pa·s,and the ink will not precipitate for 20 h.After adding the guar gum solution,when the amount is ? 1%,both inks have strong suspension stability,and no precipitation occurs after 60 days of standing.It can meet the stability requirements of ceramic ink,and the ink can be sprayed normally.After adding the guar gum solution,the ceramic ink shows special rheological properties.Based on the Windhab model,the Casson equation is introduced to correct the change of the flow curve caused by the addition of powder to establish the slip rheological model.The equation of the model is (?),where the parameter of the correction term represents the viscosity influenced by theinteraction between the particles after adding the colorant.The parameter ?'? is the viscosity of the particle-molecule combination at high shear rate affected by the entanglement between the GG molecules and the formation of the slip layer,and the parameter ?a is related to the concentration of guar gum(the number of GG molecules)and the solid content of the ink(the number of pigment particles).This model can be applied when the ink system is laminar flow,when the ink system is turbulent,a slight deviation will occur.