Process for producing ground crude pigment
AssigneeDainippon Ink and Chemicals, Inc.
InventorShunjiro Takijiri
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Abstract
An improved process for producing a ground crude pigment by grinding in the dry state a crude pigment composed of a phthalocyanine compound or a polycyclic organic pigment compound, is achieved by using a grinding apparatus comprising a cylindrical receptacle having an axis in the longitudinal direction, a stirrer having a rotating shaft disposed along the axis of the receptacle and at least two pairs of arms, each pair having arms fixed to the rotating shaft and extending outwardly toward the side wall of the receptacle, and steel balls as a grinding medium filled in the receptacle.
Claims18
In a process for producing a ground crude pigment by grinding in a dry state unsubstituted .beta.-form copper phthalocyanine, the improvement which comprises dry grinding the crude pigment in a grinding apparatus comprising a cylindrical receptacle having a side wall and a bottom wall and having an axis in a longitudinal direction, a stirrer having a rotating shaft disposed along the axis of the receptacle and at least two pairs of arms, each pair having arms fixed to the rotating shaft and extending outwardly toward the side wall of the receptacle, and steel balls as a grinding medium filled in the receptacle until the ratio of the .alpha.-form crystals to the .beta.-form crystals become 50%-80% to 50%-20%.
In a two step method for converting a crude as-synthesized compound pigment to the corresponding compound pigment of predetermined crystal form wherein the crude pigment is first dry ground to form fine highly agglomerated primary crystalline particles and thereafter the crystalline particles are treated with a solvent to convert the crystalline particles to a pigmentary state, the improvement which comprises dry grinding the crude pigment for up to 2 hours in a grinding apparatus comprising a cylindrical receptacle having a side wall and a bottom wall and having an axis in a longitudinal direction, a stirrer having a rotating shaft disposed along the axis of the receptacle and at least two pairs of arms, each pair having arms fixed to the rotating shaft and extending outwardly toward the side wall of the receptacle, and steel balls as a grinding medium filled in the receptacle.
Dependencies are inferred from the claim text.