METHOD FOR PRODUCING A DISPERSANT

Abstract

The invention relates to a method for producing a dispersant, comprising the steps of a) providing at least one water-soluble polymer comprising polyether groups, b) providing an inorganic component comprising at least one phyllosilicate which has an integral sheet charge of 0, 1 or 2, c) producing an aqueous suspension comprising the at least one water-soluble polymer comprising polyether groups and the inorganic component comprising the at least one phyllosilicate, and d) spray-drying the aqueous suspension to give a solid. Additionally disclosed is the use of the dispersant of the invention in an inorganic binder composition.

Claims

1. A method for producing a dispersant, comprising the steps of a) providing at least one water-soluble polymer comprising polyether groups, b) providing an inorganic component, comprising at least one phyllosilicate which has an integral sheet charge of 0, 1 or 2, c) preparing an aqueous suspension comprising the at least one water-soluble polymer comprising polyether groups and the inorganic component comprising the at least one phyllosilicate, d) spray-drying the aqueous suspension to give a solid.

2. The method according to claim 1, wherein the polyether groups of the at least one water-soluble polymer are polyether groups of the structural unit (I),
*U(C(O)).sub.kX(AlkO).sub.nW (I) where * indicates the bonding site to the polymer, U is a chemical bond or an alkylene group having 1 to 8 carbon atoms, X is oxygen, sulfur or a group NR.sup.1, k is 0 or 1, n is an integer whose average value based on the polymer is in the range from 3 to 300, Alk is C.sub.2-C.sub.4 alkylene, it being possible for Alk to be identical or different within the group (Alk-O).sub.n, W is a hydrogen, a C.sub.1-C.sub.6 alkyl or an aryl radical or is the group Y-F, where Y is a linear or branched alkylene group having 2 to 8 carbon atoms and may carry a phenyl ring, F is a 5- to 10-membered nitrogen heterocycle which is bonded via nitrogen and which as ring members, besides the nitrogen atom and besides carbon atoms, may have 1, 2 or 3 additional heteroatoms, selected from oxygen, nitrogen, and sulfur, it being possible for the nitrogen ring members to have a group R.sup.2, and for 1 or 2 carbon ring members to be present in the form of a carbonyl group, R.sup.1 is hydrogen, C.sub.1-C.sub.4 alkyl or benzyl, and R.sup.2 is hydrogen, C.sub.1-C.sub.4 alkyl or benzyl.

3. The method according to claim 1, wherein the water-soluble polymer comprises at least one group from the series consisting of carboxyester, carboxyl, phosphono, sulfino, sulfo, sulfamido, sulfoxy, sulfoalkyloxy, sulfinoalkyloxy, and phosphonooxy.

4. The method according to claim 1, wherein the water-soluble polymer comprising polyether groups represents a polycondensation product comprising (II) a structural unit comprising an aromatic or heteroaromatic and the polyether group, and (III) a phosphated structural unit comprising an aromatic or heteroaromatic.

5. The method according to claim 4, wherein the structural units (II) and (III) are represented by the following general formulae
A-U(C(O)).sub.kX(AlkO).sub.nW (II) where A is identical or different and is represented by a substituted or unsubstituted, aromatic or heteroaromatic compound having 5 to 10 carbon atoms in the aromatic system, the other radicals possessing the definition stated for structural unit (I); ##STR00006## where D is identical or different and is represented by a substituted or unsubstituted, aromatic or heteroaromatic compound having 5 to 10 carbon atoms in the aromatic system where E is identical or different and is represented by N, NH or O where m=2if E=N and m=1 if E=NH or O where R.sup.3 and R.sup.4 independently of one another are identical or different and are represented by a branched or unbranched C.sub.1 to C.sub.10 alkyl radical, C.sub.5 to C.sub.8 cycloalkyl radical, aryl radical, heteroaryl radical or H where b is identical or different and is represented by an integer from 0 to 300.

6. The method according to claim 4, wherein the polycondensation product comprises a further structural unit (IV) which is represented by the following formula ##STR00007## where Y independently of one another is identical or different and is represented by (II), (III) or further constituents of the polycondensation product R.sup.5 and R.sup.6 are identical or different and are represented by H, CH.sub.3, COOH, or a substituted or unsubstituted, aromatic or heteroaromatic compound having 5 to 10 carbon atoms.

7. The method according to claim 1, wherein the water-soluble polymer comprising polyether groups represents at least one copolymer which is obtainable by polymerizing a mixture of monomers comprising (V) at least one ethylenically unsaturated monomer which comprises at least one radical from the series consisting of carboxylic acid, carboxylic salt, carboxylic ester, carboxylic amide, carboxylic anhydride, and carboxylic imide and (VI) at least one ethylenically unsaturated monomer comprising the polyether group.

8. The method according to claim 7, wherein the ethylenically unsaturated monomer (V) is represented by at least one of the following general formulae from the group of (Va), (Vb), and (Vc) ##STR00008## where R.sup.7 and R.sup.8 independently of one another are hydrogen or an aliphatic hydrocarbon radical having 1 to 20 carbon atoms B is H, COOM.sub.a, COO(C.sub.qH.sub.2qO).sub.rR.sup.9, or CONH(C.sub.qH.sub.2qO).sub.rR.sup.9 M is hydrogen, a mono-, di- or trivalent metal cation, ammonium ion or an organic amine radical a is 1/3, 1/2 or 1 R.sup.9 is hydrogen, an aliphatic hydrocarbon radical having 1 to 20 carbon atoms, a cycloaliphatic hydrocarbon radical having 5 to 8 carbon atoms, or an optionally substituted aryl radical having 6 to 14 carbon atoms q independently of one another for each (C.sub.qH.sub.2qO) unit is identical or different and is 2, 3 or 4, and r is 0 to 200 Z is O, or NR.sup.16 R.sup.16 independently at each occurrence is identical or different and is represented by a branched or unbranched C.sub.1- to C.sub.10-alkyl radical, C.sub.5- to C.sub.8 cycloalkyl radical, aryl radical, heteroaryl radical or H, ##STR00009## where R.sup.10 and R.sup.11 independently of one another are hydrogen or an aliphatic hydrocarbon radical having 1 to 20 carbon atoms, a cycloaliphatic hydrocarbon radical having 5 to 8 carbon atoms, or an optionally substituted aryl radical having 6 to 14 carbon atoms R.sup.12 is identical or different and is represented by (C.sub.nH.sub.2n)SO.sub.3H where n=0, 1, 2, 3 or 4, (C.sub.nH.sub.2n)OH where n=0, 1, 2, 3 or 4; (C.sub.nH.sub.2n)PO.sub.3H.sub.2 where n=0, 1, 2, 3 or 4, (C.sub.nH.sub.2n)OPO.sub.3H.sub.2 where n=0, 1, 2, 3 or 4, (C.sub.6H.sub.4)SO.sub.3H, (C.sub.6H.sub.4)PO.sub.3H.sub.2, (C.sub.6H.sub.4)OPO.sub.3H.sub.2, or (C.sub.nH.sub.2n)NR.sup.14.sub.b where n=0, 1, 2, 3 or 4 and b=2 or 3 R.sup.13 is H, COOM.sub.a, COO(C.sub.qH.sub.2qO).sub.rR.sup.9, or CONH(C.sub.qH.sub.2qO).sub.rR.sup.9, where M.sub.a, R.sup.9, q, and r possess definitions stated above R.sup.14 is hydrogen, an aliphatic hydrocarbon radical having 1 to 10 carbon atoms, a cycloaliphatic hydrocarbon radical having 5 to 8 carbon atoms, or an optionally substituted aryl radical having 6 to 14 carbon atoms Q is identical or different and is represented by NH, NR.sup.15 or O; where R.sup.15 is an aliphatic hydrocarbon radical having 1 to 10 carbon atoms, a cycloaliphatic hydrocarbon radical having 5 to 8 carbon atoms, or an optionally substituted aryl radical having 6 to 14 carbon atoms.

9. The method according to claim 1, wherein the at least one water-soluble polymer comprising polyether groups has an average molar weight (Mw) of between 5000 and 150,000 g/mol, as determined by gel permeation chromatography.

10. The method according to claim 1, wherein the solid obtained after spray drying is in the form of powder or granules.

11. The method according to claim 1, wherein the amounts used in steps a) and b) are selected such that the solid obtained after the spray drying comprises 5 to 70 wt % of the at least one water-soluble polymer comprising polyether groups and 30 to 95 wt % of the at least one phyllosilicate which has an integral sheet charge of 0, 1 or 2.

12. The method according to claim 1, wherein the at least one phyllosilicate is a 1:1 clay mineral having a sheet charge of 0.

13. The method according to claim 1, wherein b) the inorganic component has an average particle size (d50%) as determined by laser diffractometry of between 100 nm and 2000 nm.

14. A dispersant produced by the method according to claim 1.

15. A method comprising adding the dispersant according to claim 14 in an inorganic binder composition.

Description

EXAMPLES

[0124] Polymers

[0125] Polymer 1 is a copolymer of hydroxyethyl acrylate and ethoxylated isoprenol having 23 ethylene oxide units (EO). The molecular weight (Mw) is 20 000 g/mol. The copolymer was prepared as follows: a glass reactor was fitted with a stirrer mechanism, pH meter, and metering units and was charged with 267 g of water. 330 g of the melted ethoxylated isoprenol were mixed with the water. The temperature was set at 13 C. and the pH at around 7 by addition of 25% sulfuric acid. This mixture was admixed with 4 mg of iron(II) sulfate heptahydrate, 8.25 g of mercaptoethanol, and 3.2 g of hydrogen peroxide. After that a solution of 200 g of water and 136 g of hydroxyethyl acrylate and also 5 g of Brggolit E01 and 32 g of water were added over a period of 20 minutes. During the reaction the pH was maintained at 7 by addition of 50% NaOH.

[0126] Polymer 2 is a copolymer of two ethoxylated isoprenols with different chain lengths of the ethylene oxide units (23 EO and 10 EO in a molar ratio of 1/1) and acrylic acid. The copolymer was prepared as follows: a glass reactor equipped with a plurality of feed facilities, stirrer, and dropping funnel was charged with 143 ml of water and 115 g of macromonomer 1 (prepared by ethoxylation of 3-methyl-3-buten-1-ol with 23 mol EO) and 50 g of macromonomer 2 (prepared by ethoxylation of 3-methyl-3-buten-1-ol with 10 EO) (solution A) and conditioned at 15.4 C. A portion of the second prepared, partially neutralized solution (solution B), consisting of 61.05 g of water and 12.28 g of acrylic acid (90 wt %), was added to solution A in the glass reactor over a period of 15 minutes. Additionally, 1.11 g of 3-mercaptopropionic acid were added to the reactor. A 3rd solution (solution C), was prepared, consisting of 3 g of sodium hydroxymethanesulfinate dihydrate and 47 g of water. Subsequently, at a temperature of 15.4 C., 46.5 mg of iron(II) sulfate heptahydrate, dissolved in a few drops of water, and 2.87 g of 30% hydrogen peroxide solution were added to solution A. In addition, over 45 minutes, the remaining solution B and, over 50 minutes, solution C were metered into solution A. To conclude, 25 ml of 20% sodium hydroxide solution were added and a pH of 6.5 was established.

[0127] The molecular weight was determined by gel permeation chromatography (GPC) with the following method: column combination: Shodex OH-Pak SB 804 HQ and OH-Pak SB 802.5 HQ from Showa Denko, Japan; eluent: 80 vol % aqueous solution of HCO.sub.2NH.sub.4 (0.05 mol/I) and 20 vol % MeOH; injection volume 100 l; flow rate 0.5 ml/min. The molecular weight was calibrated using standards from PSS Polymer Standard Service, Germany. For the UV detector, poly(styrene-sulfonate) standards were used, and poly(ethylene oxide) standards for the RI detector. The molecular weight was determined using the results of the RI detector.

[0128] Spray drying

[0129] A 40 wt % aqueous suspension was prepared from the respective carrier material. With vigorous stirring, the polymer was added in the form of 40 wt % aqueous solution. The suspensions were dried using a GEA Niro Mobile Minor MM-I spray dryer. Drying took place by means of a two-fluid nozzle at the top of the tower. Drying was carried out with nitrogen, which was blown in cocurrent with the material for drying, from top to bottom. 80 kg/h of drying gas were used for the drying. The temperature of the drying gas at the tower entry was 220 C. The feed rate of the material for drying was set such that the outgoing temperature of the drying gas at the tower exit was 100 C. The powder discharged from the drying tower with the drying gas was separated from the drying gas by means of a cyclone.

[0130] Spray-dryability was assessed as follows:

TABLE-US-00001 TABLE 1 Grading Description 1 Fine, dustlike powder in the sample glass beneath the cyclone; pipelines and cyclone exhibit only dustlike wetting; possibly, fine powder-like deposits in the cone of the drying tower 2 Fine powder (d(90) particle size < 500 m) in the sample glass beneath the cyclone; only slight deposits in cyclone and pipelines; possibly, fine powder-like deposits in the cone of the drying tower 3 Coarser powder (d(90) particle size > 500 m) in the sample glass beneath the cyclone, deposits in cyclone and pipelines; after 10 seconds of mixing of the powder in a RETSCH Grindomix GM 200 at 8000 revolutions/min, a sample is obtained with particle sizes d(99) < 500 m. 4 Possibly a few larger lumps in the sample glass beneath the cyclone, sample very largely in the dryer tower, severe encrustation in pipelines; 10 seconds of mixing in the RETSCH Grindomix GM 200 at 8000 revolutions/min produce a sample with particle sizes d(80) < 500 m 5 Empty, possibly waxily wetted sample glass beneath the cyclone, sample very largely in the form of waxlike coating in dryer tower and pipelines

[0131] The particle size was determined using a Mastersizer 2000 from Malvern Instruments. It represents the volumetric particle diameter.

[0132] The ground limestone used (trade name Omyacarb 15 from Omya AG) possesses an average particle diameter of 12 m. Kaolin is the commercial product ASP 602 from BASF SE. The average particle diameter is 0.6 m. Bentonite was acquired from Sigma Aldrich. The colloidal silica is the commercial product Bindzil 40/170 from Kurt Obermeier GmbH & Co. KG (40 wt %, average particle size 20 nm).

[0133] The thermomechanical properties of the powder were tested as follows:

[0134] All of the metal parts required were heated in a drying cabinet at 80 C. before use. A brass tube with a length of 70 mm and an internal diameter of 50 mm for a wall thickness of 2.5 mm were placed onto a brass baseplate with a tube attachment 7 mm high and 55 mm internal diameter. 2 g of powder were introduced into the pipe, followed by a brass cylinder having a weight of 1558 g. This cylinder was rotated by 360 10 times without pressure. The cylinder and the pipe were then removed, and the sample was classed on the basis of the following factors:

TABLE-US-00002 TABLE 2 Grading Description 1 Sample is still in powder form 2 Sample is a compacted powder, and can be broken apart by the finger or the spatula without application of force 3 Sample undergoes compaction, force required in order to disintegrate the sample, possibly slightly tacky 4 Sample is of waxlike form; initially there are soft lumps, after cooling there are hard lumps

[0135] Powders produced were as follows:

TABLE-US-00003 TABLE 3 Carrier Assessment Assessment Powder Polymer [% of total weight] A B 1 1 Finely ground 5 3 limestone [80%] 2 1 Bentonite [80%] 2 2 3 1 Kaolin [80%] 2 2 4 1 Acrylic acid/ 2 2 methacrylic acid/ methallylsulfonic acid (1/1/0.2) copolymer [80%] 5 1 Colloidal silica [80%] 2 2 6 2 Kaolin [80%] 2 2 7 2 Bentonite [80%] 2 2 C1 1 5 4 C2 2 5 4 Assessment A: Spray-dryability Assessment B: After thermal/mechanical loading C1: Comparative 1 C2: Comparative 2 Powders 3 and 6 are in accordance with the invention

[0136] The resulting powders were tested for their usefulness in a dry-mix mortar:

[0137] The cement mortar was composed of 50.0 wt % of Portland cement (CEM I 52.5 N, Milke) and 50.0 wt % of standard sand (DIN EN 196-1). The water/cement ratio, also referred to as w/c, which indicates the weight ratio of water to cement, was 0.30. To plasticize the cement mortar, a powder according to table 3 or, as a comparative, polymer 1 or polymer 2 as a 40% aqueous solution, was added. The amount of the water-soluble polymer was 2 wt % in each case, based on the amount of cement. The cement mortar was produced in a method based on DIN EN 196-1:2005 in a mortar mixer having a capacity of approximately 5 liters. For the mixing procedure, water, power or the aqueous polymer solution according to table 3 and cement were placed into the mixing vessel. Immediately thereafter the mixing operation was commenced, with the fluidizer at low speed (140 revolutions per minute (rpm)). After 30 seconds, the standard sand was added at a uniform rate within 30 seconds to the mixture. The mixture was then switched to a higher speed (285 rpm) and mixing was continued for 30 seconds more. The mixer was subsequently halted for 90 seconds. During the first 30 seconds, the cement mortar, which stuck to the wall and to the lower part of the bowl, was removed using a rubber scraper and was put into the middle of the bowl. After the break, the cement mortar was mixed at the higher mixing speed for a further 60 seconds. The total mixing time was 4 minutes.

[0138] Immediately after the end of the mixing operation, the slump flow was determined on all samples, using a Hgermann cone, with no compaction energy being supplied, in a method based on the SVB guidelines of the Deutscher Ausschuss fr Stahlbeton (German Reinforced Concrete Committee; see: Deutscher Ausschuss fr Stahlbetonbau (ed.): DAfStbGuidelines for self-compacting concrete (SVB Guidelines), Berlin, 2003). The Hgermann cone (d top=70 mm, d bottom=100 mm, h=60 mm) was placed centrally on a dry glass plate having a diameter of 400 mm and was filled with cement mortar to the level intended. Immediately after leveling had taken place, or 5 minutes after the first contact between cement and water, the Hgermann cone was taken off, held over the slumping cement mortar for 30 seconds to allow for dripping, and then removed. As soon as the slump flow came to a standstill, the diameter was determined, using a caliper gauge, at two axes lying at right angles to one another, and the average was calculated. The slump flow profile over time was characterized by repeating the test after 10, 20, 30, 45, 60, 90, and 120 minutes. Prior to each test, the cement mortar was mixed up in a mortar mixer at a rate of 140 revolutions per minute (rpm) for 10 seconds.

[0139] The end of solidification was determined on the cement paste in an analogy to DIN EN 196-3 using a Vicat needle instrument.

TABLE-US-00004 TABLE 4 End of Slump flow solid- Experiment 10 min 20 min 30 min 45 min 60 min ification Powder 1 10 cm 10 cm 10 cm 11 cm 14 cm 246 min Powder 2 10 cm 10 cm 10 cm 10 cm 10 cm 295 min Powder 3 10 cm 10 cm 11 cm 17 cm 22 cm 245 min Powder 4 10 cm 10 cm 15 cm 23 cm 28 cm 586 min Powder 5 10 cm 10 cm 10 cm 14 cm 16 cm 247 min Powder 6 30 cm 30 cm 31 cm 31 cm 32 cm Powder 7 10 cm 10 cm 10 cm 10 cm 10 cm Polymer 1 10 cm 10 cm 11 cm 17 cm 22 cm 245 min Polymer 2 30 cm 30 cm 31 cm 31 cm 32 cm Polymer 1 and Polymer 2 were metered in as a 40% aqueous solution

[0140] From table 4 it is apparent that only the inventive powder 3 (polymer 1) develops its effect on slump flow in line with the aqueous solution of polymer 1 and, furthermore, the inventive powder 6 (polymer 2) develops its activity in line with the aqueous solution of polymer 2.

[0141] The use of other carriers, such as bentonite (powder 2, cf. JP H06-239652), for instance, leads in contrast to a markedly different development of effect in terms of slump flow.

[0142] In order to show further advantages of the inventive powders relative to powders according to prior art, comparative experiments were carried out in analogy to powder 3 (see table 3). For this purpose, in experiment C3, from the same amount of anhydrous raw material, a mixture was prepared from the inorganic powder (kaolin) with the vacuum-dried, resinous dispersant (cf. DE 199 05 488). The resulting mixture was ground to give a particle size comparable with that of powder 3.

[0143] In a further experiment, C4, the inorganic powder (kaolin) was added in the drying tower during spray drying (cf. JP 2001294463). In this case, dry kaolin was metered via a stream of nitrogen into the upper part of the spraying tower. Portions of the kaolin underwent adsorption on the pasty material that forms, but the major part of the kaolin was discharged via the cyclone of the spray dryer. The polymer, however, remained in the dryer tower or the discharging pipes or in the cyclone.

TABLE-US-00005 TABLE 5 Carrier Assessment Assessment Powder Polymer [% of total weight] A B 3 1 Kaolin [80%] 2 2 C3 1 Kaolin [80%] 3 C4 1 Kaolin [80%] 5 Pastelike

[0144] For the determination of the caking tendency of the powder products, a quantity of powder presieved with a sieve having a mesh size of 500 m underwent a 7.5 kg load for 10 days in a drying cabinet at 40 C., after which the coarse fraction possibly present in the powder was determined by sieving via a screen having a mesh size of 1000 m.

TABLE-US-00006 TABLE 6 Powder Sieve residue 3 0.5 g C3 7.2 g