Water-soluble copolymers, a process for their preparation and their use as fluidizers in suspensions of solid matter

A fluidizer for suspensions of solid matter, said fluidizer being a water soluble linear copolymer comprising:

• r partial structure units of formula (C) ##STR17## wherein r is an integer and ranges from 3 to 1000, p partial structure units of formula (A) ##STR18## wherein p is an integer and ranges from 0 to 1000, and q partial structure units of formula (B) ##STR19## wherein q is an integer and ranges from 0 to 1000, with the proviso that the sum of p+q is in the range of 3.ltoreq.p+q.ltoreq.r, and wherein R.sup.1 and R.sup.2, which may be the same or different, each represent hydrogen, a C.sub.1 - to C.sub.20 -alkyl residue which may include one or more alkali metal carboxylate or alkaline earth metal carboxylate groups, at least one of which is in the position .alpha. to the nitrogen atom, an aromatic group, an aliphatic or cyclo-aliphatic residue either of which may include sulfonic acid groups or alkali metal or alkaline earth metal sulfonate groups, a hydroxyalkyl group, or may together with the nitrogen atom to which they are bound form a morpholine ring;
• M represents a hydrogen ion, a monovalent or divalent metal ion or a substituted ammonium group;
• R represents an alkylene group having 2 to 4 carbon atoms;
• R' represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms;
• a represents an integer ranging from 1 to 100;
• R.sup.3 and R.sup.4, which may be the same or different, each represent hydrogen, a C.sub.1 to C.sub.12 -alkyl residue, a phenyl residue, or may together form a di-, tri-, or tetramethylene group, which form with the inclusion of the residue of the formula:
• ##STR20## a five, six or seven membered ring;
• R.sup.5 and R.sup.6, which may be the same or different, each represent hydrogen, a C.sub.1 to C.sub.12 -alkyl residue or a phenyl residue;
• and
• X represents hydrogen, a C.sub.1 - to C.sub.4 -alkyl residue, a carboxylic acid group or a alkali metal carboxylate group.