Patent GB-1021592-A (GB)
Title: Improved process for dispersing pigments in liquid media
IPC: B02C17/16
Filed: 1964-02-06
Abstract: A method for increasing the grinding and dispersing efficiency of intermittent and continuous flow type pigment wetting, grinding and dispersing mills of the type in which the mill batch is either pumped or allowed to flow by gravity through a grinding tank in which it is agitated with granules of Ottawa sand or other suitable grinding granules, small balls or pebbles comprises diluting the mill base by intermittently or continuously injecting a variable volume or volumes of a suitable diluting vehicle into the milling chamber at one or more points so as to ensure that the consistency or structural viscosity of the mill base does not increase to the point where the milling efficiency of the mill is reduced or to the point where the mill base will fail to flow sufficiently rapidly through any screen which may be used to separate the mill base from the grinding media at the conclusion of the grinding process.  In one example, in which the mill base contains milori blue and a 35% alkyd solution, a pre-mixed base containing milori and a 25% alkyl solution is pumped into a sand mill and a diluting vehicle, which is a 42.95% solution of the same resin, is added in stages during the dispersing process. In another example, a phthalocyanine blue is dispersed by sand milling in a polymerized limed rosin 35% solution in toluol.  The resin content of the vehicle in the pre-mixed base is 40% and the diluent, which is added in stages, is a 29.13% solution of the same resin.  In a further example, colloidal carbon black is pre-mixed with a short oil alkyd solution in xylol and diluted in stages by means of a solution containing another alkyd which has still shorter oil length.ALSO:A method for increasing the grinding and dispersing efficiency of intermittent and continuous flow type pigment wetting, grinding and dispersing mills of the type in which the mill batch is either pumped or allowed to flow by gravity through a grinding tank in which it is agitated with granules of Ottawa sand or other suitable grinding granules, small balls or pebbles comprises diluting the mill base by intermittently or continuously injecting a variable volume or volumes of a suitable diluting vehicle into the milling chamber at one or more points so as to ensure that the consistency or structural viscosity of the mill base does not increase to the point where the milling efficiency of the mill is reduced or to the point where the mill base will fail to flow sufficiently rapidly through any screen which may be used to separate the mill base from the grinding media at the conclusion of the grinding process.  In one example, in which the mill base contains milori blue and a 35% alkyd solution, a pre-mixed base containing milori and a 25% alkyd solution is pumped into a sand mill and a diluting vehicle, which is a 42.95% solution of the same resin, is added in stages during the dispersing process.  In another example, a phthalocyanine blue is dispersed by sand milling in a polymerized-limed rosin 35% solution in toluol. The resin content of the vehicle in the pre-mixed base is 40% and the diluent, which is added in stages, is a 29.13% solution of the same resin.  In a further example, colloidal carbon black is pre-mixed with a short oil alkyd solution in xylol and diluted in stages by means of a solution containing another alkyd which has still shorter oil length.ALSO:A method for increasing the grinding and dispersing efficiency of intermittent and continuous flow type pigment wetting, grinding and dispersing mills of the type in which the mill batch is either pumped or allowed to flow by gravity through a grinding tank in which it is agitated with granules of Ottawa sand or other suitable grinding granules, small balls or pebbles comprises diluting the mill base by intermittently or continuously injecting a variable volume or volumes of a suitable diluting vehicle into the milling chamber at one or more points so as to ensure that the consistency or structural viscosity of the mill base does not increase to the point where the milling efficiency of the mill is reduced or to the point where the mill base will fail to flow sufficiently rapidly through any screen which may be used to separate the mill base from the grinding media at the conclusion of the grinding process.  In one example, in which the mill base contains milori blue and a 35% alkyd solution, a pre-mixed base containing milori and a 25% alkyd solution is pumped into a sand mill and a diluting vehicle, which is a 42,95% solution of the same resin, is added in stages during the dispersing process.  In another example, a phthalocyanine blue is dispersed by sand milling in a polymerized limed rosin 35% solution in toluol. The resin content of the vehicle in the premixed base is 40% and the diluent, which is added in stages, is a 29,13% solution of the same resin.  In a further example, colloidal carbon black is pre-mixed with a short oil alkyd solution in xylol and diluted in stages by means of a solution containing another alkyd which has still shorter oil length.