Spray drying method

Abstract

The invention relates to a process for producing a pulverulent composition comprising at least one polymeric dispersant (PD) which comprises structural units having anionic and/or anionogenic groups and structural units having polyether side chains, and at least one polysaccharide (PS). The process here comprises the process steps: a) production of an aqueous dispersion having a viscosity of the dispersion of less than 10 000 mPa.Math.s, comprising the at least one polymeric dispersant (PD) and the at least one polysaccharide (PS) and b) spray drying of the aqueous dispersion produced in process step a). Furthermore, the use of the pulverulent composition according to the invention in inorganic binder compositions, especially as a rheological additive, is disclosed.

Claims

1. A process for producing a pulverulent composition comprising at least one polymeric dispersant (PD) which comprises at least one structural unit comprising anionic groups and/or at least one structural unit comprising anionogenic groups and also at least one structural unit having polyether side chains, and at least one polysaccharide (PS), wherein the weight ratio of polymeric dispersant (PD) to polysaccharide (PS) is from 1/1 to 50/1 and the pulverulent composition comprises at least 65% by weight of the polymeric dispersant and the following process steps are performed: a) production of an aqueous dispersion having a viscosity of the dispersion of less than 10 000 mPa.Math.s, comprising the at least one polymeric dispersant (PD) and the at least one polysaccharide (PS), b) spray drying of the aqueous dispersion produced in process step a).

2. The process according to claim 1, wherein the polymeric dispersant (PD) is a polymer that was obtained by means of polymerization of at least one monomer having at least one anionic and/or at least one anionogenic group and of at least one monomer comprising at least one polyether side chain.

3. The process according to claim 2, wherein the polymeric dispersant (PD) has at least one structural unit of general formulae (Ia), (Ib), (Ic) or (Id): ##STR00012## in which R.sup.1 is H or an unbranched or branched C.sub.1-C.sub.4-alkyl group, CH.sub.2COOH or CH.sub.2COXR.sup.3; X is NH(C.sub.nH.sub.2n) or O(C.sub.nH.sub.2n) with n=1, 2, 3 or 4 or is a chemical bond, wherein the nitrogen atom or the oxygen atom is bonded to the CO group; R.sup.2 is OM, PO.sub.3M.sub.2 or OPO.sub.3M.sub.2; with the proviso that X is a chemical bond when R.sup.2 is OM; R.sup.3 is PO.sub.3M.sub.2 or OPO.sub.3M.sub.2; ##STR00013## in which R.sup.3 is H or an unbranched or branched C.sub.1-C.sub.4-alkyl group; n is 0, 1, 2, 3 or 4; R.sup.4 is PO.sub.3M.sub.2 or OPO.sub.3M.sub.2; ##STR00014## in which R.sup.5 is H or an unbranched or branched C.sub.1-C.sub.4-alkyl group; Z is O or NR.sup.7; and R.sup.7 is H, (C.sub.nH.sub.2n)OH, (C.sub.nH.sub.2n)PO.sub.3M.sub.2, (C.sub.nH.sub.2n)OPO.sub.3M.sub.2, (C.sub.6H.sub.4)PO.sub.3m.sub.2 or (C.sub.6H.sub.4)OPO.sub.3M.sub.2, n is 1, 2, 3 or 4; ##STR00015## in which R.sup.6 is H or an unbranched or branched C.sub.1-C.sub.4-alkyl group; Q is NR.sup.7 or O; R.sup.7 is H, (C.sub.nH.sub.2n)OH, (C.sub.nH.sub.2n)PO.sub.3M.sub.2, (C.sub.2H.sub.2n)OPO.sub.3M.sub.2, (C.sub.6H.sub.4)PO.sub.3M.sub.2 or (C.sub.6H.sub.4)OPO.sub.3M.sub.2, n is 1, 2, 3 or 4; and where each M is independently H or one cation equivalent.

4. The process according to claim 1, wherein the polymeric dispersant (PD) has at least one structural unit of general formulae (IIa), (IIb), (IIc) or (IId): ##STR00016## in which R.sup.10, R.sup.11 and R.sup.12 are each independently H or an unbranched or branched C.sub.1-C.sub.4-alkyl group; Z is O or S; E is an unbranched or branched C.sub.1-C.sub.6-alkylene group, a cyclohexylene group, CH.sub.2-C.sub.6H.sub.10, 1,2-phenylene, 1,3-phenylene or 1,4-phenylene; G is O, NH or CONH; or E and G together are a chemical bond; A is C.sub.xH.sub.2x with x=2, 3, 4 or 5 or CH.sub.2CH(C.sub.6H.sub.5); n is 0, 1, 2, 3, 4 and/or 5; a is an integer from 2 to 350; R.sup.13 is H, an unbranched or branched C.sub.1-C.sub.4-alkyl group, CONH.sub.2 and/or COCH.sub.3; ##STR00017## in which R.sup.16, R.sup.17 and R.sup.18 are each independently H or an unbranched or branched C.sub.1-C.sub.4-alkyl group; E is an unbranched or branched C.sub.1-C.sub.6-alkylene group, a cyclohexylene group, CH.sub.2-C.sub.6H.sub.10, 1,2-phenylene, 1,3-phenylene or 1,4-phenylene, or is a chemical bond; A is C.sub.xH.sub.2x with x=2, 3, 4 or 5 or CH.sub.2CH(C.sub.6H.sub.5); L is C.sub.xH.sub.2x with x=2, 3, 4 or 5 or CH.sub.2CH(C.sub.6H.sub.5); a is an integer from 2 to 350; d is an integer from 1 to 350; R.sup.19 is H or an unbranched or branched C.sub.1-C.sub.4-alkyl group; R.sup.20 is H or an unbranched or branched C.sub.1-C.sub.4-alkyl group; and n is 0, 1, 2, 3, 4 or 5; ##STR00018## in which .sub.R.sup.21, R.sup.22 and R.sup.23 are each independently H or an unbranched or branched C.sub.1-C.sub.4-alkyl group; W is O, NR.sup.25, N Y is 1 when W=0 or NR.sup.25, and is 2 when W=N; A is C.sub.xH.sub.2x with x=2, 3, 4 or 5 or CH.sub.2CH(C.sub.6H.sub.5); a is an integer from 2 to 350; R.sup.24 is H or an unbranched or branched C.sub.1-C.sub.4-alkyl group; R.sup.25 is H or an unbranched or branched C.sub.1-C.sub.4-alkyl group; ##STR00019## in which R.sup.6 is H or an unbranched or branched C.sub.1-C.sub.4-alkyl group; Q is NR.sup.10, N or O; Y is 1 when Q=O or NR10, and is 2 when Q=N; R10 is H or an unbranched or branched C.sub.1-C.sub.4-alkyl group; A is CxH2x with x=2, 3, 4 or 5, or CH2C(C6H5)H; R24 is H or an unbranched or branched C1-C4-alkyl group; M is H or one cation equivalent; and a is an integer from 2 to 350.

5. The process according to claim 2, wherein the polymeric dispersant (PD) comprises at least one polymer which is a polycondensation product comprising structural units (III) and (IV): ##STR00020## in which T is a substituted or unsubstituted phenyl radical, a substituted or unsubstituted naphthyl radical or a substituted or unsubstituted heteroaromatic radical having 5 to 10 ring atoms, of which 1 or 2 atoms are heteroatoms selected from N, O and S; n is 1 or 2; B is N, NH or O with the proviso that n is 2 when B is N and the proviso that n is 1 when B is NH or O; A is C.sub.xH.sub.2x with x=2, 3, 4 or 5 or CH.sub.2CH(C.sub.6H.sub.5); a is an integer from 1 to 300; R.sup.25 is H, a branched or unbranched C.sub.1- to C.sub.10-alkyl radical, C.sub.5- to C.sub.8-cycloalkyl radical, aryl radical or heteroaryl radical having 5 to 10 ring atoms, of which 1 or 2 atoms are heteroatoms selected from N, O and S; where the structural unit (IV) is selected from the structural units (IVa) and (IVb): ##STR00021## in which D is a substituted or unsubstituted phenyl radical, a substituted or unsubstituted naphthyl radical or a substituted or unsubstituted heteroaromatic radical having 5 to 10 ring atoms, of which 1 or 2 atoms are heteroatoms selected from N, O and S; E is N, NH or O with the proviso that m is 2 when E is N and the proviso that m is 1 when E is NH or O; A is C.sub.xH.sub.2x with x=2, 3, 4 or 5 or CH.sub.2CH(C.sub.6H.sub.5); b is an integer from 1 to 300; M is independently H or one cation equivalent; ##STR00022## in which V is a substituted or unsubstituted phenyl radical or a substituted or unsubstituted naphthyl radical; R.sup.7 is COOM, OCH.sub.2COOM, SO.sub.3M or OPO.sub.3M.sub.2; M is H or one cation equivalent; where the phenyl, naphthyl or heteroaromatic radicals mentioned are optionally substituted by 1 or two radicals selected from R.sup.8, OH, OR.sup.8, (CO)R.sup.8, COOM, COOR.sup.8, SO.sub.3R.sup.8 and NO.sub.2; and R.sup.8 is C.sub.1-C.sub.4-alkyl, phenyl, naphthyl, phenyl-C.sub.1-C.sub.4-alkyl or C.sub.1-C.sub.4-alkylphenyl.

6. The process according to claim 1, wherein the charge density of the at least one polymeric dispersant (PD) is from 1.65 mEq/g to 10.0 mEq/g.

7. The process according to claim 1, wherein the polysaccharide (PS) a) is a cellulose ether and is selected from the group of alkyl celluloses, hydroxyalkyl celluloses or alkyl hydroxyalkyl celluloses or b) is a nonionic starch ether, or c) is a microbiologically produced polysaccharide, one or more of the abovementioned polysaccharides being used in each case.

8. The process according to claim 1, wherein the water content in the aqueous dispersion of polymeric dispersant (PD) and polysaccharide (PS) from step a) is greater than 35% by weight and is less than 65% by weight.

9. The process according to claim 1, wherein the aqueous dispersion of step a), comprising the polymeric dispersant(s) (PD) and the polysaccharide(s), comprises less than 5% by weight of calcium silicate hydrate.

10. The process according to claim 1, wherein the weight ratio of polymeric dispersant (PD) to polysaccharide (PS) is from 2/1 to 50/1 and the pulverulent composition consists of at least 65% by weight of the polymeric dispersant.

11. A pulverulent composition obtained from the process according to claim 1.

12. A building material composition comprising the pulverulent composition according to claim 11 and at least one inorganic binder selected from the group of cement, calcium sulfate hemihydrate, anhydrite, slag sand, fly ash, silica dust, metakaolin, natural pozzolans, burnt oil shale, calcium aluminate cement or calcium sulfoaluminate cement.

13. A rheological additive for building material mixtures comprising one or more binders selected from the group consisting of cement, calcium sulfate hemihydrate, anhydrite, slag sand, fly ash, silica dust, metakaolin, natural pozzolans, burnt oil shale, calcium aluminate cement or calcium sulfoaluminate cement, wherein one or more of said binders comprises the pulverulent composition according to claim 11.

14. A process for the production of dry mortar mixtures in order to prevent separation of the polymeric dispersant (PD) and of the polysaccharide (PS) in the dry mortar which comprises: physically mixing a binder with the pulverulent composition of claim 11.

15. A process for producing a pulverulent composition comprising at least one polymeric dispersant (PD) which comprises at least one structural unit comprising anionic groups and/or at least one structural unit comprising anionogenic groups and also at least one structural unit having polyether side chains, and at least one polysaccharide (PS), wherein the weight ratio of polymeric dispersant (PD) to polysaccharide (PS) is from 1/1 to 50/1 nd the following process steps are performed: a) production of an aqueous dispersion having a viscosity of the dispersion of less than 10 000 mPa.Math.s, comprising the at least one polymeric dispersant (PD) and the at least one polysaccharide (PS), b) spray drying of the aqueous dispersion produced in process step a) and wherein in process step a) the aqueous dispersion is produced by initially charging an aqueous solution of the at least one polymeric dispersant (PD) which comprises more than 70% of the at least one polymeric dispersant (PD) used, and adding the at least one polysaccharide (PS) to the aqueous solution of the at least one polymeric dispersant (PD).

16. The process according to claim 15, wherein in process step a) the aqueous dispersion is produced by initially charging an aqueous solution of the at least one polymeric dispersant (PD) which comprises more than 80% of the at least one polymeric dispersant (PD) used, and adding the at least one polysaccharide (PS) in solid form to the aqueous solution of the at least one polymeric dispersant (PD).

Description

EXAMPLES

(1) PCE 1: A comb polymer made from ethoxylated hydroxybutyl vinyl ether (3000 g/mol) and acrylic acid in the ratio 10/1. Charge density 2.688 meq/g.

(2) PCE 2: A comb polymer made from ethoxylated hydroxybutyl vinyl ether (3000 g/mol) and acrylic acid in the ratio 5/1. Charge density 1.488 meq/g.

(3) PCE 3: A comb polymer made from ethoxylated hydroxybutyl vinyl ether (3000 g/mol) and acrylic acid in the ratio 2/1. Charge density 0.636 meq/g.

(4) Polymer 4: Polymer prepared according to WO15091461 A1, table 1 example 7.

(5) For example 1, into a 50% by weight solution of PCE 1 was stirred 10% by weight of a powder of Kelco-Crete DG-F (diutan gum, available from CP Kelco), based on the solids in the PCE 1 solution. The resulting suspension (formulation A) was subsequently spray dried using a two-fluid nozzle in a GEA Mobile Minor MM-I TYPE (inlet temperature 220 C., outlet temperature 98 C.). The viscosities were measured using a Brookfield viscometer (LV1 spindle) at 20 C.

(6) TABLE-US-00001 TABLE 1 Viscosity (20 C.) PCE 1 (50% by weight) 230 mPa .Math. s Kelco-Crete DG-F (10% by weight) >10 000 mPa .Math. s Formulation A 232 mPa .Math. s

(7) The resulting powder was tested in accordance with DIN EN 12706 in a mortar formulation of a ternary self-leveling composition (see table 2) against a physical mixture of the components PCE 2 and Kelco-Crete DG-F (comparative example 1). The water/binder ratio was w/b=0.6. The two powder composites (physical mixing and co-drying) were placed in a plastic bottle on a vibrating table for 24 h. A sample from the top and a sample from the bottom via punched openings in the bottle were subsequently taken from both using a spatula and tested against each other. The results of the slump after 8 min and the flow time of the DIN No. 4 Ford cups are shown in table 3.

(8) TABLE-US-00002 TABLE 2 Proportions by mass Portland cement (Milke CEM I 52.5 N) 18.5 Alumina cement (Kerneos Fondu) 11.5 CaSO4 (CAB 30) calcium sulfate binder 6.5 H33 silica sand 41.43 Ground limestone (Omyacarb 15 AL) 19.4 Redispersion powder (Vinnapas 5023 L) 2 Lithium carbonate 0.1 Vinapor DF 9010 0.1 BCK tartaric acid 0.03 Powder composite 0.34

(9) TABLE-US-00003 TABLE 3 Slump after 8 min in cm Flow time Without Example 1 (inventive) 15.9 68 sec shaking Physical mixture 15.7 63 sec (comparative example 1) After 24 h on Example 1: Sample from 15.9 67 sec the vibrating the top plate Example 1: Sample from 15.8 68 sec the bottom Comparative example 1 16.3 59 sec Physical mixture: top Comparative example 1 12.8 Not Physical mixture: bottom determinable

(10) In order the broad applicability, further liquid mixtures were produced and when possible powder samples were produced from these by means of spray drying. The preparation was effected analogously to Example 1. The liquid samples were each adjusted to a solids content of 50% by weight.

(11) TABLE-US-00004 TABLE 4 Viscosity Experiment Dispersant Thickener (mPa .Math. s) 1* PCE 2 (10% by Kelco-Crete DG-F (90% by >10000 weight) ** weight) 2* PCE 2 (20% by Kelco-Crete DG-F (80% by >10000 weight) weight) 3 PCE 2 (50% by Kelco-Crete DG-F (50% by 500 weight) weight) 4 PCE 2 (75% by Kelco-Crete DG-F (25% by 250 weight) weight) 5 PCE 2 (98% by Kelco-Crete DG-F (2% by 180 weight) weight) 6 PCE 2 (90% by Kelco-Crete DG-F (10% by 230 weight) weight) 7 PCE 1 (90% by Kelco-Crete DG-F (10% by 210 weight) weight) 8 Polymer 4 (90% Kelco-Crete DG-F (10% by 160 by weight) weight) 9 PCE 2 (90% by Culminal C-4053 190 weight) (10% by weight) 10 PCE 2 (90% by Walocel MKX 6000 (10% 180 weight) by weight) 11* PEG 1000 (90% Kelco-Crete DG-F (10% by >10000 by weight) weight) 12* PCE 2 (90% by Starvis (polyacrylamide) >10000 weight) (10% by weight) *comparative examples ** The % by weight figures in the table relate to the solids in the liquid samples Culminal C-4053 is a methyl cellulose available from Ashland Walocel MKX 6000 is a methyl hydro)wropyl cellulose available from DOW.

(12) All dried samples were shaken on a vibrating table for 24 hours and then the composition and sedimentation stability thereof were measured by means of Raman spectroscopy. The signals at 1475 cm.sup.1 and 1280 cm.sup.1 were used and integrated as signals for the polyethers. A local accumulation of a component could not be observed in any of the samples.

(13) The powders of experiments 4, 5, 8 and 9 were tested in a ternary formulation according to table 2 as in example 1. The dosage was adapted correspondingly to an identical plasticizer content.

(14) TABLE-US-00005 TABLE 5 Slump Flow time Experiment 4 15.3 cm 63 sec Experiment 5 15.2 cm 58 sec Experiment 9 14.9 cm 67 sec

(15) The powder from experiment 8, table 4 was also examined in a ternary formulation according to table 2. Due to the relatively low metering efficiency of polymer 4 in this application, the dosage of the powder composite was raised to 0.46 proportions by mass. The co-dried polymer was compared with the physical mixture.

(16) TABLE-US-00006 TABLE 6 Slump after 8 min in cm Flow time Without shaking Example 8 (inventive) 15.3 61 sec Physical mixture 15.9 65 sec (comparative example 8) After 24 h on the Example 8: Sample from 15.9 62 sec vibrating plate the top Example 8: Sample from 15.2 63 sec the bottom Comparative example 8 16.3 59 sec physical mixture: top Comparative example 8 12.4 Not physical mixture: bottom determinable