Highly concentrated aqueous suspension of minerals and/or fillers and/or pigments, stabilized with one or more polyampholytes

A process for preparing an aqueous suspension containing a dispersed substance and a dispersing agent, said dispersed substance comprising one or more members selected from the group consisting of minerals, fillers and pigments, to achieve a solids content of .gtoreq.60% by weight, and said dispersing agent carrying an external neutral or positive charge, and said dispersing agent comprising one or more members selected from the group consisting of:

• amphoteric polyelectrolytes containing anionic and cationic monomer units, the number of negative charges in the anionic monomer units equaling the number of positive charges in the cationic monomer units;
• cationic polyelectrolytes;
• amphoteric cationic polyelectrolytes in which the non-neutral monomer units each carry a predominantly positive charge;
• amphoteric anionic polyelectrolytes in which the non-neutral monomer units each carry a predominantly negative charge;
• partially neutralized anionic polyelectrolytes;
• and
• partially neutralized amphoteric anionic polyelectrolytes in which the non-neutral monomer units each carry a predominantly negative charge,
• the dispersed substance carrying a neutral or positive charge to the outside;
• said process comprising wet grinding an aqueous suspension of dispersed substance together with a dispersing and grinding agent mixture in such a manner that either:
• (a) said amphoteric polyelectrolytes are added completely before said grinding is begun, or
• (b) part of said amphoteric polyelectrolytes is added before said grinding is begun and the remainder added either during said grinding, after said grinding is terminated, or both during and after said grinding.

A process for preparing an aqueous suspension containing a dispersed substance and a dispersing agent, said dispersed substance comprising one or more members selected from the group consisting of minerals, fillers and pigments, to achieve a solids content of .gtoreq.60% by weight, and said dispersing agent carrying an external neutral or positive charge, and said dispersing agent comprising a mixture of the following components:

• (a) one or more members selected from the group consisting of cationic polyelectrolytes and amphoteric cationic polyelectrolytes in which the non-neutral monomer units carry predominantly positive charges;
• and
• (b) one or more members selected from the group consisting of partially neutralized anionic polyelectrolytes and partially neutralized amphoteric anionic polyelectrolytes in which the non-neutral monomer units carry predominantly negative charges;
• said process comprising wet grinding an aqueous suspension of said dispersed substance together with a dispersing and grinding agent mixture, in a procedure involving:
• adding part of component (b) before said wet grinding is begun and the remainder either while said wet grinding is in progress, after said wet grinding is completed or both;
• and
• either adding all of component (a) before said wet grinding is begun, or adding part of component (a) before said wet grinding is begun and the remainder either while said wet grinding is in progress, after said wet grinding is completed or both.