Quality Improvement And Rheological Characterization Of Carbon Black Gel Ink

The effect of defoaming agent of the acetylenic-modified polysiloxane emulsion on the surface tension, density, viscosity, pH value and writing performance of the carbon black gel ink was investigated. The results showed that the surface tension of the gel ink decreased slightly and the viscosity and pH value of the gel ink were not affected by the defoaming agent. The optimizational dosage of defoaming agent was 0.042wt%-0.043wt%. The pens filled with such gel ink containing defoaming agent behave good writing performance. And the writing uniformity of the gel ink pen was improved.The rheological properties of gel ink were studied. The results showed that carbon black gel ink has the characterization of pseudoplasticity. The value of power (shear thinning) index is between 0.3 to 0.6. Carbon black gel ink imported from Japan matching for needle shaped pen nib is pure viscous fluid, and the gel ink matching for bullet shaped nib is viscoelastic fluid. The storage stability predicted by dynamic time sweep is agreed with the structure stability predicted by shear stress sweep. Structure stability is the key way to understand the storage stability.The dispersity of carbon black suspension and gel ink was tested by TEM, AFM and dynamic light scattering. The stability of carbon black suspension and gel ink was studied by high speed centrifugal and rotation rheology. The results showed that the quality of carbon black suspension highly affected the stability of gel ink. The particle size has a great impact on the result of the test of centrifugal. The information of structure of gel ink can be revealed by linear viscoelastic region test.