The present invention describes silanic phtalocyanine-based dyes, the composite pigments obtainable by grafting said dyes on an inorganic substrate, and the respective processes for preparing said dyes and composite pigments.
The dyes are of the following qeneral formula:
wherein:

Pc is the residue of the phtalocyanine, possibly metallized with CO, Ni, Cu;
Ri is a hydrogen atom or an alkaline metal;
R 2 and R 3 which may be equal or different are H, alkyls having up to 4 carbon atoms, cycloalkyls or aryls;
R 4 is a C 1 -C 4 alkyl or a phenyl;
R 5 is a C 1 -C 4 alkoxyl;
n is 3, 4 or 5;
q is 0, 1;
p and m are integers so that when q is 0, p is 3 and m is 0, 1,2, or 3, and when q is 1, p is 2 and m is 0, 1, 2;
a and c are numbers comprised between 1 and 3; and
b is a number comprised between 0 and 2, chosen so that the sum a + b + c ≦ 4;

and wherein each of the four benzenic rings of the phtalocyanine is bound to only one single sulphonic group (-SO3R1) or sulphonamidic group.
The composite pigments obtained from the above-mentioned are used in varnishes, air-drying or stoving enamels, in the pigmentation of plastic materials as weel as in printing inks.