RHEOLOGY MODIFIER FOR GEOPOLYMER FOAM FORMULATIONS

Abstract

The present invention relates to the use of a cationic copolymer as a rheology modifier in a geopolymer foam formulation, a geopolymer foam formulation comprising a cationic copolymer, a process for preparing a geopolymer foam, a geopolymer foam comprising a cationic copolymer and composition for preparing a geopolymer foam formulation.

Claims

1. A method of utilizing at least one cationic copolymer (i) as a rheology modifier in a geopolymer foam formulation, comprising mixing the at least one cationic copolymer (i) with components of the geopolymer foam formulation during the preparation thereof, wherein the cationic copolymer (i) comprises at least one cationic structural unit (I) comprising at least one cationic group, and optionally at least one macromonomeric structural unit (II) comprising at least one polyoxyalkylene group.

2. The method according to claim 1, wherein a monomeric component (A) forming the structural unit (I) of the cationic copolymer (i) is selected from the group consisting of ethylenically unsaturated monomers, which comprise the at least one cationic group, and wherein a monomeric component (B) forming the structural unit (II) of the cationic copolymer (i) is selected from the group consisting of ethylenically unsaturated monomers, which comprise the at least one polyoxyalkylene group.

3. The method according to claim 1, wherein the at least one cationic group is a quaternary ammonium group, an iminium group or an N-alkylated heteroaryl group.

4. The method according to claim 1, wherein the cationic copolymer (i) comprises a) 3 to 97 mol-% of a cationic structural unit of formula (I) ##STR00023## wherein R.sup.1 in each occurrence is the same or different and represents hydrogen and/or methyl, R.sup.2 in each occurrence is the same or different and is selected from the group consisting of ##STR00024## wherein R.sup.3, R.sup.4, and R.sup.5 in each occurrence are the same or different and each independently represent hydrogen, an aliphatic hydrocarbon moiety having 1 to 20 carbon atoms, a cycloaliphatic hydrocarbon moiety having 5 to 8 carbon atoms, aryl having 6 to 14 carbon atoms and/or a polyethylene glycol (PEG) moiety, l in each occurrence is the same or different and represents an integer from 0 to 2, m in each occurrence is the same or different and represents 0 or 1, n in each occurrence is the same or different and represents an integer from 0 to 10, Y in each occurrence is the same or different and represents an absent group, oxygen, NH, and/or NR.sup.3, V in each occurrence is the same or different and represents —(CH.sub.2).sub.x—, ##STR00025## wherein x in each occurrence is the same or different and represents an integer from 1 to 6, and X in each occurrence is the same or different and represents a halogen atom, a C.sub.1-C.sub.4-alkyl sulfate, a C.sub.1-C.sub.4-alkyl sulfonate, a C.sub.6-C.sub.14-(alkyl)aryl sulfonate and/or a monovalent equivalent of a polyvalent anion, which is selected from a sulfate, a disulfate, a diphosphate, a triphosphate, and/or a polyphosphate; and optionally b) 97 to 3 mol-% of a macromonomeric structural unit of formula (II) ##STR00026## wherein R.sup.6 in each occurrence is the same or different and represents a polyoxyalkylene group of the following formula (IIa) ##STR00027## wherein o in each occurrence is the same or different and represents an integer from 1 to 300, and R.sup.1, R.sup.3, l, m, Y, V, and x have the meanings given above.

5. The method according to claim 1, wherein the cationic copolymer (i) comprises a) 3 to 97 mol-% of a cationic structural unit of formula (I) ##STR00028## wherein R.sup.1 in each occurrence is the same or different and represents hydrogen and/or methyl, R.sup.2 in each occurrence is the same or different and is selected from the group consisting of ##STR00029## wherein R.sup.3, R.sup.4, and R.sup.5 in each occurrence are the same or different and each independently represent hydrogen, an aliphatic hydrocarbon moiety having 1 to 20 carbon atoms, a cycloaliphatic hydrocarbon moiety having 5 to 8 carbon atoms, aryl having 6 to 14 carbon atoms and/or a polyethylene glycol (PEG) moiety, l in each occurrence is the same or different and represents an integer from 0 to 2, m in each occurrence is the same or different and represents 0 or 1, n in each occurrence is the same or different and represents an integer from 0 to 10, Y in each occurrence is the same or different and represents an absent group, oxygen, NH, and/or NR.sup.3, V in each occurrence is the same or different and represents —(CH.sub.2).sub.x—, ##STR00030## wherein x in each occurrence is the same or different and represents an integer from 0 to 6, and X in each occurrence is the same or different and represents a halogen atom, a C.sub.1-C.sub.4-alkyl sulfate, a C.sub.1-C.sub.4-alkyl sulfonate, a C.sub.6-C.sub.14-(alkyl)aryl sulfonate and/or a monovalent equivalent of a polyvalent anion, which is selected from a sulfate, a disulfate, a diphosphate, a triphosphate, and/or a polyphosphate; and optionally b) 97 to 3 mol-% of a macromonomeric structural unit of formula (II) ##STR00031## wherein R.sup.6 in each occurrence is pyrrolidone and/or caprolactam, and l, m, Y and V are 0 or absent groups.

6. The method according to claim 1, wherein the at least one cationic copolymer (i) comprises 10 to 90 mol.-% of the cationic structural unit (I) and 90 to 10 mol.-% of the macromonomeric structural unit (II).

7. A geopolymer foam formulation comprising the at least one cationic copolymer (i) as defined in claim 1, and (ii) at least one inorganic binder mixture comprising (iia) at least one inorganic binder selected from the group consisting of latent hydraulic binders, pozzolanic binders and mixtures thereof, and (iib) at least one alkaline activator selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, alkali metal aluminates, alkali metal silicates, and mixtures thereof; and (iii) water.

8. The geopolymer foam formulation according to claim 7, wherein the geopolymer foam formulation further comprises at least one additive selected from the group consisting of fillers, accelerators, retarders, further rheology modifiers, superplasticizers, fibers, pigments and anionic, further cationic and/or non-ionic surfactants.

9. The geopolymer foam formulation according to claim 7, wherein the geopolymer foam formulation further comprises at least one additive, which is a surfactant.

10. The geopolymer foam formulation according to claim 7, wherein the geopolymer foam formulation further comprises at least one additive, which is a further rheology modifier.

11. A process for preparing a geopolymer foam comprising (1) preparing a geopolymer foam formulation as defined in claim 7, by mixing the at least one cationic copolymer (i) with (ii) the at least one inorganic binder mixture comprising (iia) at least one inorganic binder selected from the group consisting of latent hydraulic binders, pozzolanic binders and mixtures thereof, and (iib) at least one alkaline activator selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, alkali metal aluminates, alkali metal silicates, and mixtures thereof; (iii) water; and (iv) optionally at least one additive; and (2) foaming of the resulting geopolymer foam formulation by chemical, physical and/or mechanical foaming.

12. A geopolymer foam obtained by the process according to claim 11.

13. A composition for preparing a geopolymer foam formulation comprising as components at least one cationic copolymer (i) as defined in claim 1; and (ii) at least one inorganic binder mixture comprising (iia) at least one inorganic binder selected from the group consisting of latent hydraulic binders, pozzolanic binders and mixtures thereof, and (iib) at least one alkaline activator selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, alkali metal aluminates, alkali metal silicates, and mixtures thereof; wherein the components are present separately; or the components are present in a mixture.

14. The composition according to claim 13, wherein the composition further comprises at least one additive selected from the group consisting of fillers, accelerators, retarders, further rheology modifiers, superplasticizers, fibers, pigments and anionic, further cationic and/or non-ionic surfactants.

15. The rheology modifier according to claim 6, wherein the at least one cationic copolymer (i) comprises 25 to 75 mol.-% of the cationic structural unit (I) and 75 to 25 mol.-% of the macromonomeric structural unit (II).

16. The rheology modifier according to claim 6, wherein the at least one cationic copolymer (i) comprises 40 to 60 mol.-% of the cationic structural unit (I) and 60 to 40 mol.-% of the macromonomeric structural unit (II).

17. The geopolymer foam formulation according to claim 9, wherein the geopolymer foam formulation further comprises at least one additive, which is a non-ionic surfactant.

18. The geopolymer foam formulation according to claim 9, wherein the geopolymer foam formulation further comprises at least one additive, which is an alkylpolyglucoside surfactant.

19. The geopolymer foam formulation according to claim 10, wherein the geopolymer foam formulation further comprises at least one additive, which is a further rheology modifier comprising a polymer dispersion formed from ethylenically unsaturated monomers.

Description

CATIONIC POLYMER EXAMPLES

P-1:

[0236] A cationic comb polymer composed of MPEG475-MA: 1-Vinyl-3-methylimidazolium methyl sulfate in a molar ratio of 1:6, Mw=4.0 kDa, Mn=1.7 kDa:

MPEG475-MA=methyl poly ethylene glycol (MPEG) ester of methacrylic acid having an Mn of 475 g/mol

P-2:

[0237] A cationic copolymer having no side-chains and being composed of 1-Vinyl-3-methylimidazolium chloride: N-vinylpyrrolidone in a mass ratio of 95:5, molar weight 40 kDa.

P-3:

[0238] A cationic copolymer having no side-chains and being composed of 1-Vinyl-3-methylimidazolium chloride: N-vinylpyrrolidone in a mass ratio of 50:50, molar weight 80 kDa.

Application Examples

[0239] Two sets of experiments with different binder systems were done, each set of experiments is related to the base formulations according to the tables 1 and 2. The following tables contain the components of each formulation (accelerator, (water), surfactant and inorganic binder(s) like for example metakaolin or fly ash).

TABLE-US-00001 TABLE 1 (metakaolin/fly ash based formulation): Component Mass [g] Water Glass 58 KWGL (BASF) 27.01 NaOH 1.534 Water 13.81 (in examples 1a-4 and 1b only 12.43 g) Surfactant Alkylpolyglucoside: 0.46 Glucopon 225DK (BASF) Metakaolin: Argical 1200 S 15.34 Fly ash: Flugasche Steament L10 14.43

TABLE-US-00002 TABLE 2 (metakaolin based formulation): Component Mass [g] K4 potassium water glass (Woellner) 216 NaOH 12.4 Water 111.6 Surfactant Alkylpolyglucoside: Glucopon 8 225DK (BASF) Metakaolin: Metamax (BASF) 124 Dispersion: Vinnapas 5044 24.5

General Procedures

Preparation of Unfoamed Suspensions

[0240] In a first step, by mixing of the components of each of the before standing tables (without the surfactant, but with or without the cationic polymers of examples P-1- to P-3), respective unfoamed suspensions were obtained. The density of the obtained unfoamed suspensions is summarized in each case in table 3.

Preparation of the Fresh Mineral Foams

[0241] In the second step, the surfactant Glucopon 225DK was added to the unfoamed suspensions obtained in the first step and the mixture was mixed for further 30 seconds. The suspensions were pumped by way of a hose into a fully automatic foaming machine for continuous foaming of liquids and low-viscosity pastes, operating in accordance with the stator-rotor principle (Magromix+from Heitec Auerbach GmbH). The process parameters were as follows: mixing head rotation rate 300 rpm, system air pressure approx. 2 bar, material throughput 120 liters/hour.

[0242] The air content of the obtained foamed suspensions was determined here by way of the volume change in comparison with the unfoamed suspension by a method based on DIN EN 1015-6. The densities of the foamed samples in the wet state are summarized in table 3.

[0243] A number of examples were prepared with the same base formulations as mentioned in table 1 and 2 with the same two-step procedure (1.sup.st step preparation of unfoamed suspension and 2.sup.nd step preparation of the foam) as explained in the before standing text, with or without the cationic polymers. Details are given in table 3.

Hardening of the Mineral Foams

[0244] For curing samples were stored at room temperature and 50% humidity for a period of one day.

Test Methods:

[0245] As an introduction, in the following chapter the testing methods and their technical meaning are briefly explained. The evaluation was done during or after the before mentioned three steps of producing the unfoamed suspension, the fresh mineral foams and the hardening of the mineral foams, in most of the cases by relatively simple visual test methods.

[0246] As a general remark, it is on the one side desired to obtain a good workability and foamability of the suspensions during the foaming process. During the foaming process mechanical energy is introduced into the system by the mixing process. On the one side a relatively low viscosity of the suspension is desirable in order to allow a smooth and effective foaming process. On the other side after the foaming process is finished (after mixing is finished), it is desired that the foamed samples stay stable and do not collapse until the setting (hardening) of the inorganic binder system takes place.

[0247] The relatively low viscosity of the system during the mixing, followed by a relatively high viscosity when the foamed samples are no more mixed, is a typical thixotropic behavior. The thixotropic effect is highly desirable, because it allows on the one side a smooth and readily workable foaming process and on the other side the thixotropic effect helps considerably to keep the fresh foamed sample enough stable (no collapsing of the fresh foams) until the hardening of the inorganic binder system takes place. In the following text each test method is explained in detail.

Workability Test (Foamability Test by Observation During Mixing Process)

[0248] In this test the workability of the foams is evaluated during the mixing of the unfoamed suspensions with the surfactant in order to obtain the foamed suspensions. Basically, the time for obtaining the desired density of the fresh foamed suspensions is measured. In all of the examples the test conditions were chosen in a way that the time for obtaining the desired target density of the fresh foamed suspensions is in a reasonable range (about 5 minutes). It is supposed that the viscosity of the suspensions is important for the workability, it should not be too high in order to ensure a smooth foaming process.

Stability Test (ST) (Beaker Method)

[0249] A stability test for the fresh foam samples was established as follows: a 250 mL beaker is filled with foam and tilt at an angle of 90°. The optimum result is observed if no liquid foam flows out of the beaker before setting, a slow and partial flowing out is a considerable improvement in comparison to a rather fast flowing. The stability test, especially in combination with the before mentioned workability test, is a test for thixotropy. It is desirable that the slurry viscosity during mixing is rather low, but shortly after stopping mixing the foams should be not flowable or only be little flowable in order to guarantee stability for the foams until hardening sets on.

Dripping Test (DT) (Spatula Method)

[0250] The dripping test is a similar test as the stability test (beaker method). It is also a method to evaluate the thixotropy of the foams. The dripping test is done by introducing a spatula into the freshly prepared foam and taking it out of the foam. In the ideal case the foam is so viscous that the foam adheres to the spatula and does not drip off from the spatula.

Visual Observation Test (VOT) for Cracking (Shrinkage)

[0251] The obtained samples were evaluated for cracks by visual observation after hardening. The curing conditions were storing of the samples at room temperature and 50% humidity for a period of one day. It is believed that mainly shrinkage is the reason for the crack formation.

Test Results

[0252] An overview of all the experiments and the results is given in the following table 3. As mentioned before, the workability (foamability) of all examples was chosen to be in a reasonably well workable range.

[0253] In some cases the insulation properties of the hardened foams were determined by measuring the lambda value (mW/m*K), this is a further indicator for homogeneity of hardened foams on macro- and microstructure level.

[0254] The experiments and results of table 3 show that in comparison to the examples with no addition of cationic polymers a considerable improvement of the stability of the foams (results of the stability test and the dripping test) could be achieved. The workability of the samples during mixing (foaming) was in a satisfactory range and a good thixotropic effect could be observed after stopping mixing. The samples proved to have a good foam stability.

[0255] It was also possible to reduce the amount of water (example 1a-4 and 1b) by 10 weight % without negative influence on the thixotropic effect and the workability. At the same time the cracking was in an acceptable range.

[0256] Also in the visual observation test (cracking) much better results could be obtained for the samples according to the invention, compared to the comparative examples. The number of cracks was considerably reduced as the table shows.

TABLE-US-00003 TABLE 3 overview of the experiments and the test results Visual ob- Density of Density of Base for- Polymer Lambda servation unfoamed wet foamed mulation (dosage in value Stability Dripping test (VOT) suspen- suspen- Table # wt %) .sup.1) (mW/m*K) Test .sup.2) Test .sup.3) (cracking) .sup.4) sions [g/I] sions [g/I] Annotations Example 1 Table 1 — — 3 3 3 1700 376 — (blank, comp.) Example 1a-1 Table 1 P-2 (0,3) — 2 2 2 1772 377 — Example 1a-2 Table 1 P-2 (0,7) — 2 2 2 1758 397 — Example 1a-3 Table 1 P-2 (1,5) — 2 2 1 1735 387 — Example 1a-4 Table 1 .sup.5) P-2 (0,7) — 2 2 2 1759 361 Reduced (reduced water by H.sub.2O by 10%) 10% Example 1b Table 1 .sup.5) P-1 (1,0) — 2 2 2 1723 441 Reduced (reduced water by H.sub.2O by 10%) 10% Example 2 Table 2 — 46 3 3 3 1406 217 Very instable (blank, comp.) crumbly foam, Example 2a Table 2 P-2 (1,2) 42 2 2 1 1415 215 Considerable improvement of the surface feel Example 2b Table 2 P-3 (1,2) 42 — — — — — — .sup.1) The dosage indications in wt.-% refer to the weight of the cationic polymer (dry polymer) on the weight of the components in tables 1 or 2 (water glass, NaOH, water, surfactant and respective inorganic binder(s)). .sup.2) The number 1 means an excellent result with few or no foam flowing out, 2 means a good result with a medium amount of foam flowing out and 3 means an unsatisfactory result with major amount of foam flowing relatively quickly out of the test beaker. .sup.3) Similar as in the stability test, the number 1 means an excellent result with all of the foam sticking to the spatula or nearly all of it, 2 means a medium result with some of the foam dripping from the spatula and 3 is an unsatisfactory result with major amount of foam dripping down from the spatula. .sup.4) The number 1 means a good results with no cracks being observable or only very few and minor cracks, number 2 means still a good result with a still acceptable cracking and 3 is an unsatisfactory result with heavy cracking. .sup.5) The amount of water was reduced by 10 wt %, which means that in the case of the Exam- ple 1a-4 and Example 1b instead of 13,81 g only 12,43 g of water were used.