PAINTS, PIGMENTS AND COATINGS

- Ma. Loutchelle A. Besabella

BS ChE 3

Pigments • usually inorganic in nature

• may also be pure, insoluble organic dye known as toner

• provide pleasing aesthetic appeal by making a colored surface

• reflect many of the destructive light rays, and thus help to prolong the life of the paint

considerations:

• opaque

• chemically inert

• non-toxic

• must be wet

• be of low cost

uses and applications:

• ink industries

• plastic industry

• rubber industry

• ceramic industry

• pulp and paper industry

• linoleum industries

Pigments for Surface Coatings White pigments

• Titanium dioxide

• Zinc oxide

• Lithopone

• Antimony oxide

Black pigments

• Carbon black

• Graphite

• Iron black

Blue pigments

• Ultramarine

• Copper phthalocyanine

• Iron blues

Metallics

• Aluminum

• Zinc dust

• Bronze powder

Red Pigments

• Red lead

• Iron oxides

• Cadmium reds

• Toners and lakes

Yellow Pigments

• Litharge

• Ocher

• Hansa yellows

• Ferrite yellows

• Cadmium lithopone

Orange pigments

• Lead cromate

• Cadmium orane

• Molybdnum orange

Green Pigments

• Chromium oxide

• Chrome green

• Hydrated chromium oxide

• Phthlocynine green

Brown Pigments

• Burnt sienna

• Burnt umber

• Vandyke brown

Metal protective pigments

• Red lead

• Blue lead

• Zinc, basic lead and barium potassium chromates

White pigment manufacture: titanium dioxide

Sulfate Process

raw materials:

• Ilmenite (FeTiO3)

• Sulfuric acid

methods:

• Sulfate process

• Chloride process

Titanium dioxide manufacture by sulfate process

TiOSO4 TiO2 . xH2O

TiOSO4 TiO2 . xH2O

Reactions

• FeTiO3 + 2H2SO4 TiOSO4 + FeSO4 . 2H2O

• TiOSO4 + H2O TiO2 . xH2O + H2SO4

• TiO2 . xH2O TiO2