Comb polymers as blocking additives for swelling clays
A method for inerting a swellable clay and/or for reducing or inhibiting adverse effects of swellable clays on the effectiveness of dispersants in mineral binder compositions, includes adding a comb polymer to a mineral binder composition. The comb polymer includes: at least one poly(alkylene oxide) side chain-bearing monomer unit without ionic groups, optionally at least one cationic monomer unit, optionally at least one anionic monomer unit, and optionally, at least one non-ionic monomer unit.
1. A method for inerting a swellable clay and/or for reducing or inhibiting adverse effects of swellable clays on the effectiveness of dispersants in mineral binder compositions, comprising adding a comb polymer to a mineral binder composition,
wherein the comb polymer comprises:
at least one poly(alkylene oxide) side chain-bearing monomer unit M1 without ionic groups,
optionally at least one anionic monomer unit MA,
optionally, at least one non-ionic monomer unit M3,
wherein the comb polymer, with respect to a total number of monomer units present in the comb polymer, comprises:
98-100 mol-%, of the at least one poly(alkylene oxide) side chain-bearing monomer unit M1,
0 mol-%, of a cationic monomer unit MC,
0-1 mol-%, of the at least one anionic monomer unit MA, and
0-1 mol-%, of the at least one non-ionic monomer unit M3, and
wherein the side chain-bearing monomer unit M1 includes a structure of formula I
wherein
R 1 , and R 2 , in each case independently, are H or an alkyl group having 1 to 5 carbon atoms,
R 3 , in each case independently, is H, an alkyl group having 1 to 5 carbon atoms, or a group with formula
m and m″=0, 1 or 2,
p and p″=0,
X and X″, in each case independently, is —O— or —NH—,
R 4 and R 4″ is a group of the formula -[AO] n —R a
where A is a C 2 - to C 4 -alkylene, R a is H, a C 1 - to C 20 -alkyl group, -cycloalkyl group or -alkylaryl group,
and n=2-250.
2. The method according to claim 1 ,
wherein the comb polymer consists of:
at least one poly(alkylene oxide) side chain-bearing monomer unit M1 without ionic groups,
optionally at least one anionic monomer unit MA,
optionally, at least one non-ionic monomer unit M3,
wherein the comb polymer, with respect to a total number of monomer units present in the comb polymer, consists of:
98-100 mol-%, of the at least one poly(alkylene oxide) side chain-bearing monomer unit M1,
0 mol-%, of a cationic monomer unit MC,
0-1 mol-%, of the at least one anionic monomer unit MA, and
0-1 mol-%, of the at least one non-ionic monomer unit M3, and
wherein the side chain-bearing monomer unit M1 includes a structure of formula I
wherein
R 1 , and R 2 , in each case independently, are H or an alkyl group having 1 to 5 carbon atoms,
R 3 , in each case independently, is H, an alkyl group having 1 to 5 carbon atoms, or a group with formula
m and m″=0, 1 or 2,
p and p″=0,
X and X″, in each case independently, is —O— or —NH—,
R 4 and R 4″ is a group of the formula -[AO] n —R a
where A is a C 2 - to C 4 -alkylene, R a is H, a C 1 - to C 20 -alkyl group, -cycloalkyl group or alkylaryl group,
and n=2-250.
3. The method according to claim 2 , wherein the comb polymer consists of the at least one poly(alkylene oxide) side chain-bearing monomer unit M1 without ionic groups, and the comb polymer, with respect to a total number of monomer units present in the comb polymer, comprises 100 mol-% of the at least one poly(alkylene oxide) side chain-bearing monomer unit M1.
4. The method according to claim 1 , wherein the anionic monomer unit MA in the polymer consists of a monomer which has a structure of formula III,
wherein
R 13 , in each case independently, is —COOM, —SO 2 —OM,
—O—PO(OM) 2 and/or —PO(OM) 2 ,
R 14 and R 15 , in each case independently, are H or an alkyl group having 1 to 5 carbon atoms,
R 16 , in each case independently, are H, —COOM or an alkyl group having 1 to 5 carbon atoms,
or where R 13 forms a ring together with R 16 to give —CO—O—CO—,
M independently from each other is H + , an alkali metal ion, an alkaline earth metal ion, a di- or trivalent metal ion, an ammonium ion and an organic ammonium group.
5. The method according to claim 1 , wherein the non-ionic monomer M3 has a structure of formula IV,
wherein
R 5′ , R 6′ , R 7′ , in each case independently, are H or an alkyl group having 1 to 5 carbon atoms,
m′=0, 1 or 2,
p′=0 or 1,
Y, in each case independently, is a chemical bond or —O—,
Z, in each case independently, is a chemical bond, —O— or —NH—,
R 20 , in each case independently, is an alkyl group, cycloalkyl group, alkylaryl group, aryl group, hydroxyalkyl group or acetoxyalkyl group, each having 1-20 carbon atoms.