US 12,247,128 B2
Process for preparing an aqueous suspension comprising a ground calcium carbonate-comprising material
Samuel Rentsch, Spiegel bei Bern (CH); Jacques Mongoin, Quincieux (FR); and Christian Jacquemet, Lyons (FR)
Assigned to OMYA INTERNATIONAL AG, Oftringen (CH)
Appl. No. 17/310,530
Filed by OMYA INTERNATIONAL AG, Oftringen (CH)
PCT Filed Feb. 24, 2020, PCT No. PCT/EP2020/054730
§ 371(c)(1), (2) Date Aug. 7, 2021,
PCT Pub. No. WO2020/173852, PCT Pub. Date Sep. 3, 2020.
Claims priority of application No. 19159417 (EP), filed on Feb. 26, 2019.
Prior Publication US 2022/0145083 A1, May 12, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. C09C 1/02 (2006.01); C09C 3/04 (2006.01); D21H 17/67 (2006.01); D21H 19/12 (2006.01)
CPC C09C 1/021 (2013.01) [C09C 3/041 (2013.01); D21H 17/675 (2013.01); D21H 19/12 (2013.01); C01P 2004/62 (2013.01)] 20 Claims
 
1. A process for preparing an aqueous suspension comprising a ground calcium carbonate-comprising material in a solids content of at least 70 wt.-%, based on the total weight of the suspension, the process comprising the steps of
a) providing water,
b) providing at least one calcium carbonate-comprising material,
c) providing at least one grinding aid polymer selected from the group consisting of
a homopolymer (P1) prepared from the polymerisation reaction of acrylic acid or methacrylic acid or salts thereof, the homopolymer (P1) having
an average molecular weight (Mw) as measured by gel permeation chromatography (GPC) from 3 000 to 5 000 g/mol, and
a polydispersity index (PI) from 1.5 to 2.9 as measured by gel permeation chromatography (GPC), and
carboxylic acid functions that are totally or partially neutralized
by Na+ in an amount of 70 mol-% and
by Na+, K+, Li+ or combinations thereof in an additional amount from 10 to 30 mol-%;
a copolymer (P2) prepared from the polymerization reaction of
at least one compound selected from acrylic acid, methacrylic acid, salts thereof and combinations thereof, and
at least one non-ionic compound selected from hydroxyethylacrylate, hydroxypropylacrylate, hydroxyethylmethacrylate, hydroxypropylmethacrylate, C1-C5 esters of acrylic acid, C1-C5 esters of methacrylic acid, and combinations thereof;
the copolymer (P2) having
an average molecular weight (Mw) as measured by gel permeation chromatography (GPC) from 4 000 to 20 000 g/mol, and
a polydispersity index (PI) from 1.5 to 4.0 as measured by gel permeation chromatography (GPC), and carboxylic acid functions that are totally or partially neutralized
by Na+ in an amount of 70 mol-% and
by Na+, K+, Li+ or combinations thereof in an additional amount from 10 to 30 mol-%;
and mixtures thereof,
d) forming an aqueous suspension by mixing the water of step a), the at least one calcium carbonate-comprising material of step b) and the at least one polymer of step c), e) wet grinding the at least one calcium carbonate-comprising material in the aqueous suspension of step d) in the presence of the at least one polymer in at least one wet grinding step to obtain a ground calcium carbonate-comprising material, and f) up-concentrating or partially dewatering the aqueous suspension comprising the ground calcium carbonate-comprising material obtained in step e) to achieve a higher solids content than that of step e) and the solids content achieved in step f) is at least 70 wt.-%, based on the total weight of the suspension.