Montedison S.p.a.

Massimo Rustioni

Luigi Balducci

This invention relates to new inorganic pigments consisting or consisting essentially of a TiO.sub.2 rutile nucleus, of a first adherent coating of trigonal Al.sub.2 O.sub.3 and of a second adherent coating of cubic MeAl.sub.2 O.sub.4, in which Me is Co, Ni, Cu, Zn or Mg. These pigments are obtained by mixing TiO.sub.2 rutile particles coated with Al.sub.2 O.sub.3, with a MeO oxide or a Me compound capable of providing MeO in a subsequent calcination step, and by calcining the mixture in the presence of air at temperatures in the range of from 750.degree. to 1000.degree. C.

Rutile (TiO.sub.2) pigments coated with (1) trigonal anhydrous alumina

This invention relates to new inorganic yellow pigments consisting or consisting essentially of Bi.sub.1-(x/3) M.sub.x V.sub.1-x O.sub.4 in which M is Mo or W. The value of x varies from 0.075 to 0.317 in the case of Mo and from 0.059 to 0.265 in the case of W. These pigments are composed of only the tetragonal crystalline phase of the scheelite type when M is Mo; when M is W, also the orthorhombic crystalline phase .gamma.Bi.sub.2 WO.sub.6 is present. These pigments may also contain a crystalline phase consisting of orthorhombic BaSO.sub.4 ; in such case the amount of BaSO.sub.4 may reach 80% by weight of the pigment.

Molybdenum or tungsten containing bismuth vanadate yellow pigments and

The present invention concerns new inorganic pigments and a process for their preparation. More particularly, it relates to new bismuth vanadate based yellow pigments. The pigments of this invention include orthorhombic barium sulphate as a diluent, said diluent being in an amount comprised between 10 and 90% by weight of the total composition.

New inorganic pigments and process for their preparation

New greenish-yellow pigments based on BiVO.sub.4 are disclosed. The pigments consist of the product obtained by the calcination, in the presence of air, of a mixture of BiPO.sub.4, V.sub.2 O.sub.5 and an oxide MeO, in which Me is Ca, Ba, Mg or Zn, said calcining being conducted at a temperature of between 500.degree. and 800.degree. C. when Me is Ca, Ba or Mg; and between 500.degree. and 700.degree. C. when Me is Zn, the calcination being then followed by a slow cooling down and by wet grinding. These pigments show a molar ratio Bi.sub.2 O.sub.3 /P.sub.2 O.sub.5 equal to 1 while their molar ratios Bi.sub.2 O.sub.3 /V.sub.2 O.sub.5 are within given ranges, which depend on the nature of Me.

Bismuth vanadate pigments and process for preparing same

There are disclosed new greenish-yellow, yellow and orange-yellow pigments which consist substantially of bismuth vanadate of monoclinic structure, bismuth phosphate of monoclinic structure and aluminum phosphate of orthorhombic structure and which, in the case of the yellow and orange-yellow pigments, also comprise a compound based on Bi.sub.2 O.sub.3 and V.sub.2 O.sub.5 the X-rays diffraction pattern of which shows the following peaks: 1.87, 1.88, 2.41, 2.77, 2.80, 3.11, 3.82 and 7.6 A. The new pigments are characterized by a dominant wave length .lambda..sub.D of from 573 to 586 m.mu., and have a molar ratio of Bi.sub.3 O.sub.3 /P.sub.2 O.sub.5 equal to 1, and a Bi.sub.2 O.sub.3 /V.sub.2 05 molar ratio of from 1.39 to 5.59, inclusive, while their molar ratio Al.sub.2 O.sub.3 /V.sub.2 O.sub.5 lies within specified ranges of values. Also disclosed is a method for preparing the new pigments by calcining, in the presence of air, BiPO.sub.4, Al.sub.2 O.sub.3 and V.sub.2 O.sub.5 or compounds which generate Al.sub.2 O.sub.3 and V.sub.2 O.sub.5 during the calcination.

Growing community of inventors

Pozzolo Formigaro, Italy

Massimo Rustioni