Fluid Behavior
Non-Newtonian fluid behavior causes liquid viscosity to decrease significantly as applied mechanical shear rate increases. Shear thinning rheology enables textile print pastes and liquid coatings to flow smoothly through fine screen meshes or micro-nozzles under high pressure, then instantly thicken once applied to the fabric surface. This reversible fluid behavior prevents ink spreading and maintains sharp design edges.
Application Dynamic
High squeegee forces inside a rotary printing screen subject the print paste to intense localized shear, temporarily lowering resistance to flow. Exhibiting shear thinning rheology allows the paste to transfer effortlessly into yarn intersections. Once the squeegee passes and shear forces drop to zero, the paste instantly recovers high static viscosity, stopping capillary bleed into surrounding unprinted areas.
Rheological Control
Formulators blend synthetic thickeners, carboxymethyl cellulose, or sodium alginate into dye liquors to adjust flow dynamics. Controlling shear thinning rheology is critical for high-resolution printing on smooth synthetic fabrics. Laboratory rotational viscometers measure paste viscosity across varying shear rates to ensure stable performance under dynamic mill printing conditions.
Viscosity Boundary
Newtonian fluids like un-thickened water solutions display constant viscosity regardless of shear, causing uncontrolled bleeding on textile substrates. Excessively high structural recovery speeds prevent print paste from leveling properly, causing uneven surface texture.
