Regulating The Coating Morphology And Properties Of C.I. Pigment Red 170 By Surface Modification Via Hydrous Alumina

Organic pigments have many advantages,for instance,high brilliance,bright tone,excellent transparence,good photosensitivity,and low-toxicity,while inorganic pigments have other advantages,such as,good ultraviolet resistance,high thermal stability and excellent solvent resistance.Organic pigments surface modification with inorganic materials can combine all these advantages together and eventually obtain new composite pigments.In this paper,hydrous alumina was coated on the surface of Pigment Red170 particles by hydrolysis of Al₂?SO₄?₃,and hydrous alumina layers on Pigment Red 170 particles surface with different coating morphologies were obtained.In addition,the relationship between the coating morphologies and the properties of Pigment Red 170 were discussed.Specific work is as follows:The coating process was thoroughly studied.The effects of different pretreatment coating process for Pigment Red 170 dispersion were explored,as well as the effects of pH,temperature and feeding rate of Al₂?SO₄?₃ on the formation of hydrous alumina coating layers on the surface of Pigment Red 170 particles.Three types of coating morphologies:dots,floccules and films,were obtained,which were characterized by transmission electron microscopy?TEM?,scanning electronic microscopy?SEM?,?-potential analysis,ultraviolet-visible absorption spectroscopy?UV-vis?,ultraviolet visible diffuse reflectance spectroscopy?UV-vis DRS?,X-ray photoelectron spectroscopy?XPS?,X-ray powder diffraction spectrum?XRD?and thermogravimetric analyzer?TGA?.The relationship between the coating morphologies and the properties of Pigment Red 170 were explored.UV-vis spectroscopy,TGA and bleeding test indicated that the UV scattering property,thermal stability and solvent resistance all can be improved by the hydrous alumina coating layer.And the more continues and dense the coating is,the greater the improvement of UV scattering property,thermal stability and solvent resistance could be achieved,and which reveals that the consecutiveness and density of the coating layers should be the key factors for the improvement of the UV scattering property,thermal stability and solvent resistance of the organic pigments.