Zhou Chunlong

Properties of copper phthalocyanine microencapsulated in polystyrene by phase separation

Abstract Copper phthalocyanine (CuPc) was microencapsulated by liquid phase separation in an organic solvent using a polystyrene (PS) wall. Experimental results show that the molecular weight of PS effects properties of CuPc such as flowability, dispersing ability, wetting property and particle size. The wetting angle for the microcapsule is increased, and flowability and dispersing level (in toluene) of microencapsulated CuPc are improved significantly. A better pigment dispersion can be prepared by PS using a loading of 2–5%. Thus it is possible to reduce the viscosity of a dispersion coloured with microencapsulated CuPc and increase the solids loading of the dispersion system.

Modification study involving a Naphthol as red pigment

Abstract This paper is concerned with the modification study on a Naphthol red pigment (known in China as 808 Scarlet) synthesized by coupling aniline with Naphthol AS, on the surface of inorganic cores. We also report the use of Tobias acid to modify the aniline in the coupling step, producing a mixed coupling. As the size of the inorganic core decreases, surfaces of silica gel are fully covered with coupling component, and the resultant coated pigment is made by the naphthol coupling component reacting with the diazonium component on the inorganic core surface. The results of these experiments show that the resistance to heat, color strength, shade and dispersing stability (in aqueous media) of the modified pigment made by the “coated core” method and the mixing coupling technique are all increased.

An investigation of the thermal stability of some yellow and red azo pigments

Abstract A series of benzimidazolone and phthalimide derivatives has been synthesized. 2-Amino-5-nitrohenzonitrile was hydrolyzed during its diazotization with nitrosoylsulfuric acid at 70°C to give the diazonium salt of 2-carboamoyl-4-nitroaniline. A series of yellow and red pigments was prepared and their m.p., temperature of color change and TGA determined. The presence of cyano, amide, chloro and methoxy groups improved the thermal stability; methylation of the -NHCONH- and -CONHCO- groups had an adverse effect on the thermal stability, the decomposition temperature being lowered.

Properties of copper phthalocyanine blue (C.I. Pigment Blue 15:3) treated with poly(ethylene glycol)s

This paper is concerned with the surface treatment of copper phthalocyanine blue (C.I. Pigment Blue 15:3) by adsorption with poly(ethylene glycol)s of various molecular weights. The results from the experiments show that the contact angle for water, the flowability and the mean diameter of treated pigment particles decrease, and that the dispersing stability in aqueous media is increased after treatment. The effect of surface treatment depends largely on the molecular weights of the poly(ethylene glycol)s and on the amount of the poly(ethylene glycol)s used.

Synthesis of derivatives of Naphtol AS containing polar groups and modification used for C.I. Pigment Red 57

Abstract The synthesis of derivatives of Naphtol AS containing polar groups (–COOH, –SO3H) and factors affecting the reaction have been studied. Four derivatives of Naphtol AS containing –COOH or –SO3H groups in the 3- or 4- position of the phenyl ring were synthesized. Derivatives of Naphtol AS as the second coupling component were used in mixed coupling and the effect of its added amount on the colour strength, hue, flowability and dispersing extent (in water) of pigments was studied.

An investigation of complex modification of Benzidine Yellow G

Benzidine Yellow G (C.I. Pigment Yellow 12) was successively modified through mixed coupling with sulfo derivatives of acetoacetanilide and fatty amines. The hydrocarbon chain of the fatty amine enclosed the polar sulfo groups, and properties such as flowability, wettability, and dispersibility were greatly improved after the pigment was treated with stearylamine.

An investigation of organic dye-coloured nacreous pigments

The preparation of some coloured mica-titanium dioxide nacreous pigments has been investigated. The results showed that some mordant and direct dyes were the preferred precursor materials. The effects of reaction conditions, such as temperature, pH and reaction time, on the quality of the coloured nacreous pigments were also studied.