QUICK-DRYING TWO-COMPONENT COATING MASS AND METHOD FOR THE PRODUCTION OF SAME

Abstract

The present invention relates to a process for producing an aqueous coating composition on the basis of a fast-curing hydraulic binder, the coating composition being applied in liquid form to a substrate, and also to the corresponding coating composition. The coating composition additionally comprises an organic polymeric binder, a retardant, and a curing accelerator. Following prior activation, the coating compositions produce coatings having improved through-drying properties.

Claims

1: A process for producing an aqueous coating composition, the process comprising, in a specified order: preparing an aqueous paste-like first component by mixing at least one fast-curing hydraulic binder and at least one retardant selected from the group consisting of boric acid, orthophosphoric acid, metaphosphoric acid, phosphonic acid, phosphorous acid, an organic phosphonic acid derivative, tartaric acid, and citric acid thereby forming a first mixture, adding at least one curing accelerator selected from the group consisting of lithium sulfate and lithium acetate to the first mixture, thereby forming a second mixture, and adding at least one organic polymeric binder to the second mixture, and adding a second component comprising at least one activator.

2: The process according to claim 1, wherein the at least one activator is added immediately before applying the aqueous coating composition.

3: The process according to claim 1, wherein the aqueous paste-like first component further comprising at least one additive.

4: The process according to claim 1, wherein the aqueous paste-like first component comprises, based in each case on a total weight of the aqueous paste-like first component: 5 to 30 wt % of the at least one fast-curing hydraulic binder; 0.1 to 8 wt % of the at least one retardant; 0.5 to 5 wt % of the at least one curing accelerator; 5 to 60 wt % of the at least one organic polymeric binder; 0 to 5 wt % of at least one additive; 10 to 60 wt % of water; amounts adding up to 100 wt %.

5: The process according to claim 1, wherein a weight ratio of the at least one organic polymeric binder to the at least one fast-curing hydraulic binder is from 1:1 to 1:0.08.

6: The process according to claim 1, wherein the aqueous paste-like first component further comprises mineral fillers.

7: The process according to claim 1, wherein the aqueous paste-like first component comprises, based in each case on a total weight of the aqueous paste-like first component: 1 to 28.5 wt % of the at least one fast-curing hydraulic binder; 0.02 to 7.6 wt % of the at least one retardant; 0.1 to 4.75 wt % of the at least one curing accelerator; 1 to 57 wt % of the at least one organic polymeric binder; 0 to 4.75 wt % of at least one additive; 5 to 80 wt % of mineral fillers; and 2 to 57 wt % of water.

8: The process according to claim 6, wherein a fraction of the aqueous paste-like first component is from 90 to 98 wt % and a fraction of the second component is from 2 to 10 wt %, based on a total weight of the aqueous coating composition.

9: The process according to claim 1, wherein the at least one fast-curing hydraulic binder is at least one selected from the group consisting of calcium aluminate cement and calcium sulfoaluminate cement.

10: The process according to claim 1, wherein the at least one retardant is phosphoric acid, boric acid or a mixture of the phosphoric acid and the boric acid.

11: The process according to claim 1, wherein the at least one curing accelerator is lithium sulfate.

12: The process according to claim 1, wherein the at least one activator is an alkali metal hydroxide.

13: The process according to claim 1, wherein the aqueous paste-like first component is prepared by first introducing the at least one fast-curing hydraulic binder into an aqueous solution of the at least one retardant and then introducing the the at least one curing accelerator and the at least one organic polymeric binder in succession into a resulting mixture.

14: An aqueous composition, comprising a paste-like component, wherein the past-like component which comprises: at least one fast-curing hydraulic binder, at least one retardant selected from the group consisting of boric acid, orthophosphoric acid, meta-phosphoric acid, phosphonic acid, phosphorous acid, and an organic phosphonic acid derivative, at least one curing accelerator selected from the group consisting of lithium sulfate and lithium acetate, and at least one organic polymeric binder.

15: The composition according to claim 14, wherein the paste-like component is obtainable by a process, comprising, in a specified order: mixing the at least one fast-curing hydraulic binder and the at least one retardant, thereby forming a first mixture; adding the at least one curing accelerator to the first mixture, thereby forming a second mixture; adding the at least one organic polymeric binder to the second mixture; and adding a second component comprising at least one activator.

16: An aqueous coating composition, which is present in at least two parts (I) and (II), wherein the part (I) comprises the aqueous composition as defined in claim 14 and the part (II) comprises a component comprising an activator.

17: A sealing membrane, comprising: the aqueous composition of claim 14.

18: A process for preparing a sealing membrane comprising: preparing the aqueous coating composition by the process of claim 1, and applying the aqueous coating composition to a substrate for curing.

19: A sealing membrane, comprising: the aqueous coating composition of claim 16.

Description

EXAMPLE 1

[0044] Coating compositions having the constitution indicated in table 1 were produced, with the addition first of lithium sulfate and then of the polymer to the suspension comprising passivated rapid-setting cement (containing aluminate cement plus retardant). Lastly, where provided, the sodium hydroxide solution was added.

TABLE-US-00001 TABLE 1 Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Suspension of 90 90 90 passivated rapid-setting cement (corresponding to slurry 2 from US 2014/0343194) .sup.1) Portland cement 52.5N 188 Polymer.sup.2) 180 180 180 180 132.7 Water 120 120 120 156 117 Dispersant 5 5 5 5 Defoamer 4 4 4 4 3.7 Lithium sulfate 8 8 Finely ground limestone 389 389 389 453 75 Fine sand 200 200 200 200 483 Microsilica 1 1 1 1 Cellulose ether 0.75 0.75 0.75 0.75 Thickener 3 3 3 0.75 0.6 Total 1000 1000 1000 1000 1000 pH trigger (20% strength 10 10 NaOH) .sup.1) Water 38.115%; phosphoric acid (85% strength) 1.19%; dispersant (sodium polyacrylate) 1%; aluminate cement 59.38%; xanthan gum 0.3%; biocide (isothiazolone) 0.015% (in each case % by weight, based on the total weight of the suspension) .sup.2)Copolymer based on n-butyl acrylate, acrylonitrile, and methacrylic acid.

[0045] The coating composition constituted as above was mixed up using a laboratory mixer. Of the compositions from trials 1 to 3, in each case 250 g were introduced into a plastic beaker and sealed firmly with a lid, so that no moisture can escape and after a short time an atmospheric humidity over the composition of 100% is established. Trial 1 therefore corresponds to the pastelike first component (a) without activating agent (b). In a second trial, the same composition was activated with sodium hydroxide solution, and placed into a beaker in the same way as in trial 1. Both beakers were stored with closed lid at room temperature (23 C.). At certain time intervals (pot life), the beakers were opened and the viscosity is tested by stirring with a spatula knife. The results are given in table 2.

TABLE-US-00002 TABLE 2 Composition Composition Composition Pot life from trial 1 from trial 2 from trial 3 After 15 min no stiffening tough no stiffening After 30 min no stiffening tough no stiffening After 60 min no stiffening plastic no stiffening After 1:30 h no stiffening hard no stiffening After 2 h no stiffening no stiffening After 2:30 h no stiffening no stiffening After 3 h no stiffening no stiffening After 3:30 h no stiffening no stiffening After 4 h no stiffening no stiffening After 4:30 h no stiffening no stiffening After 5 h no stiffening no stiffening After 7 h no stiffening no stiffening After 24 h no stiffening hard

[0046] The activated composition from trial 2 is hard after 1:30 h, whereas even after 24 h no curing can be observed in the inactivated composition from trial 1. Likewise, the activated composition from trial 3, which admittedly does not contain a curing accelerator in contrast to the composition from trial 2, is still not hard after 7 h.

Example 2

[0047] Three beakers are prepared with the compositions 1 to 3 from example 1 in the same way and are stored at 5 C. Here again, after appropriate intervals of time, the through-curing of the composition is tested.

TABLE-US-00003 Composition Composition Composition Pot life from trial 1 from trial 2 from trial 3 After 15 min no stiffening no stiffening no stiffening After 30 min no stiffening no stiffening no stiffening After 60 min no stiffening no stiffening no stiffening After 1:30 h no stiffening tough no stiffening After 2 h no stiffening tough no stiffening After 2:30 h no stiffening tough/plastic no stiffening After 3 h no stiffening plastic no stiffening After 3:30 h no stiffening plastic no stiffening After 4 h no stiffening hard no stiffening After 4:30 h no stiffening no stiffening After 5 h no stiffening no stiffening After 7 h no stiffening no stiffening After 24 h no stiffening no stiffening

[0048] Example 2 shows that while the activated system does react with a delay at low temperatures, in comparison to example 1, it nevertheless still undergoes through-curing. The unactivated system (composition from trial 1) and also the activated but not accelerated system (composition from trial 3) show no reaction within 24 h.

Example 3

[0049] The composition from trial 1, along with 20% strength sodium hydroxide solution and two concrete slabs, were stored in a conditioning cabinet at 7 C. and 95% atmospheric humidity for 24 hours. Thereafter one concrete slab was coated with the composition from trial 1 (plate 1). The application rate in this case was 1.5 kg/m.sup.2. The second concrete slab was coated in the same way with the activated formulation (composition from trial 1+1% sodium hydroxide solution) (plate 2). After the coating operation, the two concrete slabs were immediately stored again at 7 C. and 95% air humidity in the conditioning cabinet. The time up to the through-curing of the layers was determined (drying time). For this purpose, the coating was contacted with a finger, which was turned by 90 degrees on the surface under gentle pressure. Through-curing is sufficient when no imprints or instances of damage are apparent. In that case the layer has solidified to a point at which it is possible to apply a further, second layer by roller or toothed spreader.

[0050] The trials are repeated at different atmospheric humidities; the results are shown in table 3:

TABLE-US-00004 TABLE 3 Drying time (min) Plate 1 Plate 2 Temp.: 7 C. at 80% humidity 1st layer 195 125 2nd layer 180 110 Temp.: 7 C. at 85% humidity 1st layer 230 140 2nd layer 240 130 Temp.: 7 C. at 90% humidity 1st layer 270 160 2nd layer 255 140 Temp.: 7 C. at 95% humidity 1st layer 340 300 2nd layer 335 300

[0051] The trials show that the new system with activation is particularly effective in the 80-90% atmospheric humidity range and at low temperature.

Comparison of the Crack Bridging and Tensile Adhesive Strength:

[0052] The compositions from trials 1, 4, and 5 in example 1 are subjected to comparative testing of the crack bridging according to DIN EN 14891 and of the tensile adhesive strength according to DIN EN 1348. The results are shown in table 4.

TABLE-US-00005 TABLE 4 Composition Composition Composition Testing from trial 1 from trial 4 from trial 5 Crack bridging to 1.49 mm 2.85 mm 0.8 mm DIN EN 14891 (application: 3 kg/m.sup.2) Tensile adhesive strength to 1.12N/mm.sup.2 0.76N/mm.sup.2 1.7N/mm.sup.2 DIN EN 1348 after 28 days' storage at 23 C., 50% rel. humidity

[0053] The results from table 4 show that the new activated system from trial 1, in comparison to a standard cementitious sealing slurry (trial 5), exhibits significantly better crack bridging and, in comparison to the cement-free system from trial 4, a significantly better tensile adhesive strength.