Filler for Wall Coatings

Abstract

A filler for wall coating compositions, wherein said filler consists of particles, wherein said particles are fired mixtures of 40 to 70% by weight of clay minerals 5 to 32% by weight of crystalline silicic acids 10 to 45% by weight of feldspar 0 to 20% by weight of other aggregates,
and wherein said particles have a d50 grain size of from 1 μm to 40 μm.

Claims

1. A filler for wall coating compositions, wherein said filler consists of particles, wherein said particles are fired mixtures of 40 to 70% by weight of clay minerals 5 to 32% by weight of crystalline silicic acids 10 to 45% by weight of feldspar 0 to 20% by weight of other aggregates, and wherein said particles have a d50 grain size of from 1 μm to 40 μm.

2. The filler according to claim 1, wherein said particles are fired mixtures of 40 to 70% by weight of clay minerals 5 to 30% by weight of crystalline silicic acids 10 to 30% by weight of feldspar 0 to 20% by weight of other aggregates.

3. The filler according to claim 1, wherein the particles have a d50 grain size of from 3 μm to 40 μm.

4. The filler according to claim 1, wherein said clay minerals are selected from the group consisting of kaolin, dickite, nacrite, halloysite, vermiculite, and mixtures thereof.

5. The filler according to claim 1, wherein the crystalline silicic acids are selected from the group consisting of quartz, cristobalite, tridymite, and mixtures thereof.

6. The filler according to claim 1, wherein the other aggregates are selected from the group consisting of alumina (Al.sub.2O.sub.3), tectosilicates that are not feldspars, phyllosilicates that are not clay minerals, silicates that are not tecto- or phyllosilicates, carbonates, and mixtures thereof.

7. The filler according to claim 1, wherein said filler has a lead content of less than 300 ppmw, preferably less than 200 ppmw, respectively measured by means of X-ray fluorescence analysis according to DIN 51001:2003-08, and/or an amorphous fraction of more than 10%, as measured by means of X-ray diffraction followed by Rietveld refinement.

8. The filler according to claim 1, wherein said filler has an oil number of less than 80 g/100 g, preferably 50 g/100 g or less, respectively measured according to DIN EN ISO 787-5:1995-10, and/or a solar reflection across the total spectrum of at least 85%, measured according to ASTM Standard C 1549-16.

9. The filler according to claim 1, wherein said filler has a softening temperature of less than 1720° C., measured according to DIN 51730:2007-09, a hemisphere temperature of less than 1740° C., measured according to DIN 51730:2007-09 or both.

10. A wall coating composition, comprising the filler according to claim 1 and at least one binder.

11. The wall coating composition according to claim 10, wherein said filler is contained therein in an amount of from 2 to 25% by weight.

12. A process for producing a filler for wall coating compositions, wherein said filler consists of particles, comprising: a) firing a mixture of 40 to 70% by weight of clay minerals 5 to 32% by weight of crystalline silicic acids 10 to 45% by weight of feldspar 0 to 20% by weight of other aggregates; b) crushing the fired mixture, c) grinding the crushed fired mixture to particles, wherein said particles have a d50 grain size of from 1 μm to 40 μm.

13. A process for producing a wall coating composition, comprising: mixing the filler according to claim 1 with at least one binder.

14. A method of increasing the wet abrasion resistance of wall coatings, comprising adding particles that are fired mixtures of 40 to 70% by weight of clay minerals 5 to 32% by weight of crystalline silicic acids 10 to 45% by weight of feldspar 0 to 20% by weight of other aggregates, and have a d50 grain size of from 1 μm to 40 μm, into a wall coating composition.

15. A method of reducing the amount of binder used in wall coating compositions comprising adding particles that are fired mixtures of 40 to 70% by weight of clay minerals 5 to 32% by weight of crystalline silicic acids 10 to 45% by weight of feldspar 0 to 20% by weight of other aggregates, and have a d50 grain size of from 1 μm to 40 μm, into a wall coating composition having a reduced amount of binder.

Description

EXAMPLE 1: PREPARATION OF FILLERS

[0087] Articles having the following composition were prepared by firing in an oxidizing atmosphere at 1200° C.: [0088] 60% by weight of kaolin [0089] 21% by weight of quartz [0090] 19% by weight of feldspar

[0091] These articles were subsequently crushed to a d50 grain size of approximately 1 mm.

[0092] Then, the crushed articles were ground. The following d50 grain sizes were obtained:

TABLE-US-00001 Sample 1 Sample 2 Sample 3 3.3 μm 5.4 μm 11.8 μm

[0093] Commercially available calcined kaolin (china clay) (DORKAFILL® H, Gebrüder Dorfner GmbH & Co. Kaolin- und Kristallquarzsandwerke KG, Hirschau, Germany) was used as a comparative sample in Examples 2, 3, 4, 7 und 8. It had a d50 grain size of 11.6 μm as measured with a CILAS laser granulometer. It has a mullite index of 45.

EXAMPLE 2: OIL NUMBER

[0094] The oil number of the samples was determined according to DIN EN ISO 787-5:1995-10. The following oil numbers were measured:

TABLE-US-00002 Comparative Sample 1 Sample 2 Sample 3 sample 47 g/100 g 41 g/100 g 35 g/100 g 80 g/100 g

[0095] Samples 1 to 3 according to the invention has essentially lower oil numbers than those of the comparative sample. Wall coating compositions prepared by using samples 1 to 3 therefore had a lower need for a binder as compared to wall coating compositions in which the calcined kaolin was used.

EXAMPLE 3: LEAD CONTENT

[0096] The lead content of the samples was determined by means of X-ray fluorescence analysis according to DIN 51001:2003-08. The following lead contents were measured:

TABLE-US-00003 Comparative Sample 1 Sample 2 Sample 3 sample <150 ppmw <150 ppmw <150 ppmw 1200 ppmw

[0097] Because of the low lead contents, the fillers according to the invention (samples 1 to 3) are safe in terms of health hazards. In contrast to the comparative sample, the use of the fillers according to the invention in wall coatings is possible without any problem.

EXAMPLE 4: SOLAR REFLECTION

[0098] The total solar reflection for an angle of incidence of 20° with the perpendicular line was measured by using a “Solar Spectrum Reflectometer” Model SSR of the company Devices and Services, Dallas, Tex., USA. For this purpose, a representative and sufficiently large partial quantity of the sample to be measured was removed. A sample pan having a diameter of 55 mm was filled with the sample up to a level of 10 mm, the surface was smoothened using a spatula. The solar reflection value is stated as a mean of five measurements. The solar reflection over the entire spectrum and the solar reflection in the UV range (UV reflection) were determined. The particles had the following properties:

TABLE-US-00004 Comparative Sample 1 Sample 2 Sample 3 sample Solar reflection 92.5% 91.4% 91.9% 92.5% (entire spectrum) UV reflection 83.1% 81.0% 79.5% 77.2%

[0099] The fillers according to the invention (samples 1 to 3) had an increased solar reflection in the high energy UV range as compared to the comparative sample. Facade paints in which the fillers according to the invention are used are capable of reflecting incident solar radiation in the UV range very well.

EXAMPLE 5: SOFTENING AND HEMISPHERE TEMPERATURE

[0100] The melting behavior of the samples on a hot stage microscope was examined. According to DIN 51730:2007-09, a specimen molded into a cube was heated, and its deformation was recorded by an imaging method. During the melting, characteristic points (softening temperature, hemisphere temperature, flow temperature) can be described. A hot stage microscope from Linseis was used. The samples had the following properties:

TABLE-US-00005 Samples 1, 2 and 3 Comparative sample* Softening 1695° C. 1737° C. temperature Hemisphere 1720° C. >1740° C. temperature Flow temperature >1740° C. >1740° C. *Calcined kaolin (AS 45 from the company Amberger Kaolinwerke Eduard Kick GmbH & Co. KG)

EXAMPLE 6: AMORPHOUS FRACTION

[0101] The amorphous fraction of the samples was determined by X-ray diffraction followed by Rietveld refinement. Thus, the samples were ground fine, followed by making records with an X-ray diffractometer (Malvern-Panalytical EMPYREAN).

[0102] From these records, the mineral inventory was determined. In another step, 10% by weight of rutile was added to each sample, in order to determine also the amorphous fraction of each sample in addition to the crystalline components by a Rietveld analysis. The samples had the following amorphous fraction:

TABLE-US-00006 Samples 1, 2 and 3 Comparative sample* 16% 9% *Calcined kaolin (AS 45 from the company Amberger Kaolinwerke Eduard Kick GmbH & Co. KG)

EXAMPLE 7: WALL COATING COMPOSITION

[0103] An aqueous dispersion paint having a pigment volume concentration of 80% was prepared. It had the following composition:

TABLE-US-00007 Component % by weight Water 30.1 Calgon N 0.05 BYK 155/35 0.9 BYK 014 0.2 Acticide MBS 0.1 Walocell XM 6000 PV 0.5 Walocel XM 30.000 PV 0.1 Kronos 2300 10 CaCO.sub.3 Omyacarb 2 38 Sample 1, 2, 3 or comparative sample 10 Mowilith LDM 1871 10 BYK 014 0.2 Acrysol RM 8 W 0.1 Total 100.0

EXAMPLE 8: WET ABRASION RESISTANCE

[0104] In order to determine the wet abrasion resistance of the wall coating, the deaerated spreadable paints from Example 7 (containing either one of samples 1, 2 or 3 or commercially available calcined kaolin (DORKAFILL® H, Gebrüder Dorfner GmbH & Co. Kaolin- and Kristallquarzsandwerke KG, Hirschau) as a filler) were applied to a black-and-white paint card (company Erichsen GmbH & Co. KG) with a film thickness of 200 μm using a film applicator (product Zehntner, type ZAA 2300) using a doctor blade. After the doctor blade coating, they were dried for two weeks according to standard DIN EN ISO 11998:2006-10. The measurement of the wet abrasion resistance was effected according to DIN EN ISO 11998:2006-10, in which the surface to be tested is loaded with a defined number of cycles. The mean loss of layer thickness is stated as the wet abrasion. The wet abrasion resistance was determined with a wash abrasion and scrub test device model 494 MC of the company Erichsen GmbH & Co. KG. The following values for the wet abrasion were determined:

TABLE-US-00008 Comparative Sample 1 Sample 2 Sample 3 sample 45.3 μm 30.8 μm 14.9 μm 32.1 μm

[0105] The fillers according to the invention (samples 1 to 3) allowed for the production of wall paints having very good wet abrasion resistance values. Excellent values could be achieved with particles of samples 2 and 3.