Dispersant for calcium sulphate-based compositions

Patent metadata

Field	Value
Publication number	US-10988415-B2
Application number	US-201615762521-A
Country	US
Kind code	B2
Filing date	Sep 22, 2016
Priority date	Sep 24, 2015
Publication date	Apr 27, 2021
Grant date	Apr 27, 2021

Abstract

The present invention relates to the use of a copolymer as a dispersant for binder compositions based on calcium sulfate, the copolymer having a polymer backbone and sidechains bound thereto, and at least one ionizable monomeric unit M1 and at least one sidechain-carrying monomeric unit M2, characterized in that the copolymer has, in a direction along the polymer backbone, a non-random distribution of the monomeric units M1 and/or of the monomeric units M2.

First claim

The invention claimed is:

1. A method comprising introducing a copolymer as a dispersant into a binder composition that includes at least one mineral binder, the binder composition being based on calcium sulfate, wherein
the copolymer comprises a polymer backbone and side chains bonded thereto and there are at least one ionizable monomer unit M1 and at least one side chain-bearing monomer unit M2,
the copolymer has a nonrandom distribution of the monomer units Ml and/or the monomer units M2 in a direction along the polymer backbone in that the copolymer has a gradient structure in at least one section AA in a direction along the polymer backbone with respect to the ionizable monomer unit M1 and/or with respect to the side chain-bearing monomer unit M2, and the copolymer, in addition to the at least one section AA having a gradient structure, has a further section AB, wherein there is essentially a constant local concentration of the monomers and/or a statistical or random distribution of the monomers over the entire section AB,
a proportion of the calcium sulfate, based on all the mineral binder in the binder composition, is at least 30% by weight,
a molar ratio of the monomer units Ml to the monomer units M2 in the copolymer is in the range of 0.5-6,
the ionizable monomer unit M1 in the copolymer has a structure of the formula I

the side chain-bearing monomer unit M2 includes a structure of the formula II

where
R 1 forms a ring together with R 4 to give —CO—O—CO—, or R 1 , in each case independently, is —COOM and/or —SO 2 -0M, and R 4 , in each case independently, is H, —COOM or an alkyl group having 1 to 5 carbon atoms;
M, independently of one another, represents H + , an alkali metal ion, an alkaline earth metal ion, a di- or trivalent metal ion, an ammonium ion or an organic ammonium group;
R 2 , R 3 , R 5 and R 6 , in each case independently, are H or an alkyl group having 1 to 5 carbon atoms;
R 7 , in each case independently, is H, —COOM or an alkyl group having 1 to 5 carbon atoms;
m=0, 1 or 2;
p=0 or 1;
X, in each case independently, is —O— or —NH—;
R 8 is a group of the formula -[AO] n —R a, where A=C 2 − to C 4 -alkylene, R a is H, a C l - to C 20 -alkyl group, -cycloalkyl group or -alkylaryl group; and
n=2-250.

2. The method as claimed in claim 1 , wherein the copolymer comprises the gradient structure and a block structure comprising an essentially constant local concentration of monomers.

3. The method as claimed in claim 1 , wherein the copolymer comprises at least one further monomer unit MS of the formula III:

where R 5′ and R 6′ , in each case independently, are H or an alkyl group having 1 to 5 carbon atoms,
R 7′ is H, —COOM or an alkyl group having 1 to 5 carbon atoms,
m′=0, 1 or 2, and
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 9 , 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.

4. The method as claimed in claim 1 , wherein the copolymer further comprises at least one first block A consisting of the ionizable monomer unit M1 and at least one second block B consisting of the side chain-bearing monomer unit M2.

5. The method as claimed in claim 1 , wherein the polydispersity of the copolymer is <1.5.

6. The method as claimed in claim 1 , wherein the molar ratio of the monomer units M1 to the monomer units M2 in the copolymer is in the range of 2-3.5.

7. The method as claimed in claim 1 , wherein R 1 =COOM; R 2 and R 5 , independently of one another, are H, —CH 3 or mixtures thereof; R 3 and R 6 , independently of one another, are H or —CH 3 , and where X in at least 75 mol % of all monomer units M2 is —O—.

8. The method as claimed in claim 1 , wherein the copolymer is prepared by a controlled free-radical polymerization and/or a living free-radical polymerization.

9. The method as claimed in claim 1 , wherein the copolymer is used for control of the setting characteristics of the binder composition.

10. The method as claimed in claim 1 , wherein all the copolymer present in the binder composition as a dispersant contains only monomer units that are selected from the group consisting of the ionizable monomer unit M1 and the side chain-bearing monomer unit M2.

Assignees

• Sika Tech Ag

Inventors

• Weidmann Jürg
• Hampel Christina
• Zimmermann Jörg

Classifications

• C04B28/14

  containing calcium sulfate cements {(gypsum-paper plates E04C)} · CPC title

• C08F293/005

  using free radical "living" or "controlled" polymerisation, e.g. using a complexing agent · CPC title

• C08F2438/03

  Use of a di- or tri-thiocarbonylthio compound, e.g. di- or tri-thioester, di- or tri-thiocarbamate, or a xanthate as chain transfer agent, e.g . Reversible Addition Fragmentation chain Transfer [RAFT] or Macromolecular Design via Interchange of Xanthates [MADIX] · CPC title

• C04B24/246

  containing polyether side chains · CPC title

• C04B24/165 Primary

  containing polyether side chains · CPC title