Tham khảo tài liệu 'coatings technology handbook episode 2 part 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Organic Pigments 78-3 FIGURE Structure of copper phthalocyanine blue pigment blue 15 . Organic Blues Copper Phthalocyanine Blue The major blue used within the coatings industry is copper phthalocyanine blue PB 15 with its usage far outweighing other blues such as Indathrone blue PB 60 . Phthalocyanines are planar molecules with a tetrabenzotetraazoporphin structure as shown in Figure . Manufacture is comparatively easy despite the superficial complexity of the phthalocyanine molecule. Reaction of a phthalic acid derivative at temperatures approximating 190 C with a source of nitrogen such as urea and a metal or metal salt is usually all that is required to produce the appropriate metal phthalocyanine. Molybdate vanadates and certain compounds of titanium have been found to be useful catalysts for this condensation reaction. Figure illustrates the chemistry behind the production of copper phthalocyanine blue. This condensation reaction results in the formation of copper phthalocyanine in a crude nonpigmentary form. The product has thus to be finished or conditioned to give the pigment grade of choice. Typically crude phthalocyanine blue is characterized by a crystal size of the order of 50 pm a purity in excess of 92 and a poor pigmentary strength. Metal-free phthalocyanine blue PB 16 is normally manufactured via the sodium salt of phthalonitrile. Acid pasting is used to condition the crude and give the pigment. Copper phthalocyanine is commercially available in two crystal forms known as the a and p. The a form is described by the designations Pigment Blue 15 15 1 and 15 2 and is a bright red-shade blue pigment. The p form is described as Pigment Blue 15 3 and 15 4 and is a bright green or peacock shade. The a form is meta-stable and requires special treatment to stabilize the crystal against its tendency to O O NH NH O O O NH NH NH Copper Salt _ Copper Catalyst Complex Heat nC-Ị X C Cv ll n-Cu-n Il C M C N FIGURE Chemistry of .
