Stabilizers for silicate paints

Abstract

The invention relates to a silicate coating containing (A) at least one compound of the formula (I), ##STR00001##
where R.sup.1 represents H, C.sub.1-C.sub.4-alkyl, CH.sub.2CH.sub.2OH, or CH.sub.2CH(CH.sub.3)OH, (B) at least one silicate binder, (C) if appropriate, one or more polymer binders, (D) if appropriate, further additives usual for the production of silica coatings, and (E) water.

Claims

1. A dispersion comprising (A) at least one compound of the formula (I) ##STR00004## in which R.sup.1 is C.sub.1-C.sub.4, alkyl, CH.sub.2CH.sub.2OH or CH.sub.2CH(CH.sub.3)OH, (B) at least one silicate binder, (C) at least one polymeric binder, and (E) water.

2. The dispersion as claimed in claim 1, further comprising as component (D) one or more of the constituents selected from the group consisting of pigments, dispersants, defoamers, coalescents, rheological additives, biocides, wetting agents, and alkalis.

3. The dispersion as claimed in claim 1, wherein R.sup.1 is methyl or CH.sub.2CH.sub.2OH.

4. The dispersion as claimed in claim 1, wherein R.sup.1 is methyl.

5. The dispersion as claimed in claim 1, wherein the concentration of the compound of the formula (I) is 0.01 to 10 wt %.

6. The dispersion as claimed in claim 1, wherein the concentration of the compound of the formula (I) is 0.02% to 5%.

7. The dispersion as claimed in claim 1, which comprises a quaternary ammonium compound.

8. The dispersion as claimed in claim 7, in which the quaternary ammonium compound is selected from the group consisting of compounds of the formulae (II a) and (II b) ##STR00005## in which R.sup.3, R.sup.4, R.sup.5, and R.sup.8 independently of one another are C.sub.1-C.sub.6 alkyl; R.sup.2 is C.sub.1-C.sub.2 alkyl, CH.sub.2CH.sub.2OH or CH.sub.2CH(CH.sub.3)OH; R.sup.6 and R.sup.7 independently of one another are H or C.sub.1-C.sub.4 alkyl; n, x and y independently of one another are a number between 1 and 10, and X is an anion selected from the group consisting of halides, nitrites, nitrates, carbonates, phosphates, phosphonates, hydroxides, sulfates and sulfonates.

9. The dispersion as claimed in claim 8, in which the compounds of the formula (I) and (II) are used in a ratio of 0.5:1 to 1:0.5.

10. The dispersion as claimed in claim 8, in which the compounds of the formula (I) and (II) are used in a ratio of 0.75:1 to 1:0.75.

11. The dispersion as claimed in claim 1, further comprising a white or chromatic pigment in an amount from 10 to 70 wt %.

12. The dispersion as claimed in claim 1, further comprising wetting agents or dispersants in an amount from 0.01 to 10 wt %.

13. The dispersion as claimed in claim 1, further comprising defoamers in an amount from 0.01 to 5 wt %.

14. The dispersion as claimed in claim 1, further comprising biocides in an amount from 0.01 to 5 wt %.

15. The dispersion as claimed in claim 1, further comprising coalescents in an amount from 0.01 to 5 wt %.

16. The dispersion as claimed in claim 1, further comprising rheological additives in an amount from 0.1 to 10 wt %.

17. The dispersion as claimed in claim 1, comprising the polymeric binder (C) in an amount from 0.01 to 70 wt %.

18. The dispersion as claimed in claim 1, comprising the polymeric binder (C) in an amount from 0.5 to 50 wt %.

19. The dispersion as claimed in claim 1, further comprising alkali in an amount from 0.01 to 10 wt %.

20. The dispersion as claimed in claim 1, comprising 0.1 to 40 wt % of constituent (B).

21. The dispersion as claimed in claim 1, comprising 0.5 to 25 wt % of constituent (B).

22. The dispersion as claimed in claim 1, comprising 1 to 80 wt % of water.

23. The dispersion as claimed in claim 1, in which the compound of formula (I) is prepared from glucose.

24. A method for stabilizing silicatic coating which comprises at least one silicate binder, at least one polymeric binder, and water, comprising the step of adding at least one compound of the formula (I) ##STR00006## in which R.sup.1 is C.sub.1-C.sub.4, alkyl, CH.sub.2CH.sub.2OH or CH.sub.2CH(CH.sub.3)OH to the silicatic coating.

25. The method as claimed in claim 24, in which the compound of the formula (I) is combined with at least one quaternary ammonium compound.

26. The method as claimed in claim 25, in which the quaternary ammonium compound corresponds to the formula (II a) and/or (II b) ##STR00007## in which R.sup.3, R.sup.4, R.sup.5, and R.sup.8 independently of one another are C.sub.1-C.sub.6 alkyl; R.sup.2 is C.sub.1-C.sub.2 alkyl, CH.sub.2CH.sub.2OH or CH.sub.2CH(CH.sub.3)OH; R.sup.6 and R.sup.7 independently of one another are H or C.sub.1-C.sub.4 alkyl; n, x and y independently of one another are a number between 1 and 10, and X is an anion selected from the group consisting of halides, nitrites, nitrates, carbonates, phosphates, phosphonates, hydroxides, sulfates and sulfonates.

27. The method as claimed in claim 26, in which the compounds of the formula (I) and (II) are used in a ratio of 0.5:1 to 1:0.5.

28. The method as claimed in claim 26, in which the compounds of the formula (I) and (II) are used in a ratio of 0.75:1 to 1:0.75.

Description

EXAMPLES

(1) Percentages in this description are weight percentages based on the weight of the overall composition, unless otherwise specified.

(2) In a comparison series, the nitrogen-containing compounds of table 1 were investigated in silicatic coatings for their effects on the rheology. The viscosity and change in viscosity over the storage time show the extent of the thickening. The yield point and the thixotropy area show the force required to render the silicatic coating flowable, in order to allow uniform application of the paint. The change over the storage time shows how quickly the thixotropy is reestablished and so prevents uniform leveling.

(3) The rheological measurements were conducted on a HAAKE MARS III rheometer (Thermo Scientific). A solvent trap filled with water and sample-space cover were used for each measurement.

(4) The viscosity was measured using a cone/plate geometry (1° 60 mm) at 20° C. A rotation ramp with shear rate specification between 1 and 200 s.sup.−1 was measured, and the viscosity value was read off at a shear rate of 60 s.sup.−1.

(5) The thixotropy was determined via the evaluation of the hysteresis area between upward and downward rotation ramps with shear rate specification between 0.1 and 1000 s.sup.−1. The measurements were carried out with a cone/plate geometry (1° 60 mm) at 23° C.

(6) Before the determination of the yield point, the sample was applied to the measuring plate, sheared at 0.1 s.sup.−1 for 5 minutes, and left to stand for 5 minutes (structure recovery phase). Then a rotation ramp with shear stress specification between 0.01 and 80 Pa was carried out. The yield point was determined by the tangent method in a double-logarithmic plot of the measurement curve. The measurements were carried out with a plate/plate geometry (35 mm-gap 1 mm) at 23° C.

(7) TABLE-US-00001 TABLE 1 Stabilizers used Stabilizer Description Type of example N,N,N′,N′- Tertiary diamine compound Comparative Tetrahydroxyalkyl-α-ω- Betolin ® Q 40, Wöllner example alkylamine N-Methylglucamine Compound I with R.sup.1 = H Inventive example N,N-Dimethylglucamine Compound I with R.sup.1 = CH.sub.3 Inventive example

(8) TABLE-US-00002 TABLE 2 Composition of the silicate paints in wt % Item Raw material Function wt % 1 Water Solvent 24.5 2 Tylose H 30.000 P2 Cellulose thickener 0.4 3 Sapetin D27 Wetting agent 0.2 4 DispersogenSPS Stabilizer (quaternary 1 ammonium compound) 5 Agitan E 256 Defoamer 0.15 6 Tiona 595 White pigment 10 7 Finntalc M30SL Filler 5 8 Omyacarb 2 GU Filler 10 9 Omyacarb 5 GU Filler 16 10 Omyacarb extra GU Filler 3.7 11 Water Solvent 1 12 Mowilith LDM 6119 Binder 9 13 Water Solvent 1 14 Silres BS 1306 Silicone oil 0.65 15 Betolin K28 Alkali 16 16 Stabilizer as per table 1 Stabilizer 0.2 17 Water Solvent 0.2 18 Agitan E 256 Defoamer 0.15 19 Water Solvent 0.85 Total 100

(9) A silicate paint was formulated in accordance with table 2. For this purpose, components 1-5 were homogenized at room temperature by successive addition at 100 to 300 rpm by means of a Getzmann dissolver with sawtooth stirrer. Components 6-10 were subsequently dispersed at a high shear rate (1000-1300 rpm). Finally, components 11 to 19 were added in succession and homogenized at 1300 rpm.

(10) The properties of the silicate paint of table 2, when additized with a stabilizer as per table 1, are shown in table 3.

(11) TABLE-US-00003 TABLE 3 Examples 1 (C) to 3 in silicate paint Example 1 (C) 2 3 Stabilizer N,N,N′,N′- N- N,N- Tetrahydroxyalkyl- Methyl- Dimethyl- α-ω-alkylamine glucamine glucamine Viscosity after 24 h 622 mPas 420 mPas 401 mPas storage at room temperature Viscosity after 2186 mPas 970 mPas 873 mPas 28 days' storage at room temperature pH 11 11 11 Yield point after 3.4 Pa <1 Pa 2.6 Pa 24 h storage at room temperature Yield point after 11 Pa 2.7 Pa 8.0 Pa 28 days' storage at room temperature Thixotropy area 21.7 kPa/s 4.4 kPa/s 4.5 kPa/s after 7 days' storage at room temperature Thixotropy area 41.9 kPa/s 15.4 kPa/s 11.8 kPa/s after 28 days' storage at room temperature

(12) Table 3, example 1 (C) shows a higher viscosity and a greater rise in viscosity relative to the invention (examples 2 & 3). The smaller thixotropy area and yield point of examples 2 and 3 points to easier working with the silicate paints.

(13) TABLE-US-00004 TABLE 4 Composition of the organosilicate paints in wt % Item Raw material Function wt % 1 Water Solvent 20 2 Tafigel FUR 40 PU thickener 0.3 3 Tylose MH 6000 YG8 Cellulose thickener 0.08 4 Lopon 890 Wetting agent 0.3 5 Dispersogen SPS Stabilizer (quaternary 0.16 ammonium compound) 6 Agitan E 256 Defoamer 0.4 7 Wükonil HB 3000 Wax 2 8 Tiona 595 White pigment 17.5 9 Finntalc M30SL Filler 5 10 Omyacarb 2 GU Filler 8.5 11 Omyacarb 5 GU Filler 6.5 12 Omyacarb extra GU Filler 12 13 Water Solvent 1 14 Mowilith LDM 1828 Binder 17 15 Water Solvent 1 16 Tafigel FUR 44 PU thickener 0.5 17 Potassium hydroxide solution Alkali 1 (10% strength) 18 Betolin K28 Waterglass 3.5 19 Stabilizer as per table 1 Stabilizer 0.2 20 Water Solvent 0.2 21 Agitan E 256 Defoamer 0.15 22 Water Solvent 1.67 Total 100

(14) An organosilicate paint was formulated in accordance with table 4. For this purpose, components 1-7 were homogenized at room temperature by successive addition at 100 to 300 rpm by means of a Getzmann dissolver with sawtooth stirrer. Components 8-13 were subsequently dispersed at a high shear rate (1000-1300 rpm). Finally, components 14 to 22 were added in succession and homogenized at 1300 rpm.

(15) The properties of the organosilicate paint of table 4, when additized with a stabilizer as per table 1, are shown in table 5.

(16) TABLE-US-00005 TABLE 5 Examples 4 (C) to 6 in organosilicate paint Example 4 (C) 5 6 Stabilizer N,N,N′,N′- N- N,N- Tetrahydroxyalkyl- Methyl- Dimethyl- α-ω-alkylamine glucamine glucamine Viscosity after 24 h 1441 mPas 838 mPas 832 mPas storage at room temperature Viscosity after 2855 mPas 1567 mPas 1463 mPas 28 days' storage at room temperature pH 11 11 11 Yield point after 5 Pa 1 Pa 4 Pa 24 h storage at room temperature Yield point after 9 Pa 5 Pa 6 Pa 28 days' storage at room temperature Thixotropy area 36 kPa/s 33 kPas/s 28 kPas/s after 7 days' storage at room temperature Thixotropy area 57 kPa/s 48 kPa/s 42 kPa/s after 28 days' storage at room temperature

(17) Table 5, example 4 (C) shows a higher viscosity and a greater rise in viscosity relative to the invention (examples 5 & 6). The smaller thixotropy area and yield point of examples 5 and 6 points to easier working with the organosilicate paints.