BASIC, HYDROPHOBIC FILLER, COATING COMPOSITION CONTAINING A FILLER OF THIS KIND

Abstract

The present invention relates to a filler, in particular a powdery filler, for a coating composition, in particular for a paint, a lacquer or an impregnating agent. The invention is characterised in that the filler comprises particles which have a surface coating, the particles comprising a siliceous or carbonatic component and having a basic pH value in aqueous solution, and the surface coating of the particles comprising one of the substances alkyltrimethoxysilane, alkyltriethoxysilane and/or alkyl siloxane. The invention furthermore relates to a coating composition containing a filler of this kind. In addition, the invention relates to uses of a filler of this kind for treating stones, ceramics or construction materials against moisture penetration, corrosion and algae, mold and/or plant growth.

Claims

1. Filler, in particular powdery, for a coating composition, in particular for a paint, a lacquer or an impregnating agent, characterised in that the filler comprises particles which have a surface coating, the particles comprising a siliceous or carbonatic component and having a basic pH value in aqueous solution, and the surface coating of the particles comprising one of the substances alkyltrimethoxysilane, alkyltriethoxysilane and/or alkyl siloxane.

2. Filler according to claim 1, characterised in that the surface coating comprises a hydrophobic component.

3. Filler according to claim 1, characterised in that the particle consists of partially calcined dolomite, calcium silicate hydrate and/or kaolin.

4. Filler according to claim 1, characterised in that the alkyl group of at least one substance of the surface coating of the particles comprises at least one carbon chain having 6 to 12 carbon atoms, preferably between 7 and 10 carbon atoms, particularly preferably 8 carbon atoms.

5. Filler according to claim 1, characterised in that the surface coating of the particle has ion-exchange properties.

6. Filler according to claim 1, characterised in that the particles have a diameter of between 0.01 m and 5 mm, preferably in a range of from 0.02 m to 2 mm, particularly preferably in a range of from 0.05 m to 1 mm

7. Filler according to claim 1, characterised in that the weight proportion of the surface coating of the particles is less than 10%, preferably between 0.5 and 8%, more preferably between 1 and 5% of the total weight of the filler.

8. Coating composition comprising a filler according to claim 1, characterised in that the filler is suspended in the coating composition, the weight proportion of the filler being between 5% and 80%, particularly preferably between 10 and 50%, very particularly preferably between 12 and 25% of the total weight of the coating composition.

9. Coating composition according to claim 8, characterised in that the coating composition has a pH value of less than 11.5, preferably of between 5.5 and 11.5, particularly preferably of between 10.0 and 11.5.

10. Coating composition according to claim 8, characterised in that the coating composition further comprises a corrosion inhibitor, the corrosion inhibitor amounting to less than 3%, preferably less than 2%, particularly preferably less than 1%, and very particularly preferably less than 0.5% of the total weight of the coating composition.

11. Use of a filler that comprises particles having a surface coating, the particles comprising a siliceous or carbonatic component and having a basic pH value in aqueous solution, and the surface coating of the particles comprising one of the substances alkyltrimethoxysilane, alkyltriethoxysilane and/or alkyl siloxane, in a coating composition for treating stones, ceramics, metals or construction materials against moisture penetration, corrosion and algae, mold and/or plant growth.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] FIG. 1 is a graph showing the water absorption coefficients against time, shown by temporally successive measurements.

DETAILED DESCRIPTION OF THE INVENTION

[0047] FIG. 1 illustrates the determination of the water absorption coefficient (w-value) for paving stones coated with a coating system that comprises 15% filler. The test is carried out in accordance with DIN EN 1062-3:2004. The paving stones were wetted for 6 hours, weighed, re-dried for 18 hours, and weighed again. Uncoated kaolin particles were used as a comparison material. As can be seen in FIG. 1, in the test conditions selected, the w-value of materials comprising a silicate compound, shown by the dashed line having square measuring point symbols, and a carbonate compound, shown by a solid line having crosses as measuring point symbols, remains close to the base line in each case. In contrast, for kaolin not coated with the coating system described, the w-value increases continuously, as shown in FIG. 1 by a dotted line having circles as measuring point symbols. Unlike in the case of the uncoated kaolin, the water absorption within the specified times can thus be reduced in the systems coated as described above.

[0048] In order to test the growth-inhibiting property of the filler, growth tests were carried out for the following organisms: [0049] Aspergillus niger, [0050] Staphylococcus aureus, [0051] Bacillus Megaterium, [0052] Chlorella vulgaris and [0053] Pseudomonas aeruginosa.

[0054] It was possible to confirm the effectiveness for all these organisms. For this purpose, inter alia the tests set out in the following were carried out, which tests provided the results set out in each case.

[0055] a) Zone of Inhibition Test

[0056] The filler was tested when applied to agar that was subsequently inoculated. When tested on (Baird-Parker Agar) BP Agar, an inhibiting effect on the growth of Staphylococcus aureus was observed. When tested on (Luria Agar) L-Agar, it was possible to observe a growth-inhibiting effect on Bacillus Megaterium. It was also possible to inhibit the growth of Chlorella vulgaris on algal-agar.

[0057] b) Tests in Paint

[0058] In further tests, it was also possible to observe inhibition of the growth of Aspergillus niger and Pseudomonas aeruginosa (in addition to the organisms already mentioned above). In these tests, a paint for roof tile coatings was supplemented with 15% filler, mounted on filter paper, and the coated filter paper was laid on agar (coating on the side remote from the agar) and subsequently inoculated. The inhibition of the growth was even better when filler was worked into a binder. These tests furthermore showed that it is advantageous for the surface of the filler to be accessible, and that it is advantageous to use the filler in systems that are as highly filled as possible and/or in open systems.

[0059] c) Testing the Coating in Algal Suspension

[0060] In these tests, a paint for roof tile coatings was supplemented with 15% filler and mounted on filter paper. The coated filters were then placed in algal suspension and exposed to sunlight for 20 days at 28-30 C. The growth on the coatings was subsequently assessed. Using the strongly basic, hydrophobic filler made it possible to prevent growth.

[0061] d) Resistance of Exterior Paints to Mold Fungi and Algae

[0062] The resistance to algae was tested in a manner analogous with DIN EN 15458:2014. For this purpose, PVC test specimens were coated with paint to be tested and conditioned in a 23/50 climate. Sterilisation by means of gamma irradiation was subsequently carried out. The sterile test specimens are doused with a mixed algal suspension and incubated until significant algal growth has formed (approx. 2 weeks). The suspension is drained off, the growth on the test specimen surface assessed visually, and the batches are incubated for a further 2 weeks. The test specimens are then removed, assessed visually, and dried. A further assessment was carried out after cleaning using deionised water, by means of rinsing and drying.

[0063] It was possible to observe reduced growth of the tested organisms green algae (Stichococcus bacillaris) and blue algae (Gloeocapsa atrata), as well as easier cleaning of algal growth from the surface.

[0064] The effectiveness of a filler according to the invention in terms of the corrosion-resistance properties can be seen from the following example:

[0065] The hydrophobic, basic filler was subjected to a salt spray test, in accordance with EN ISO 9227, for 240 hours, in an amount of 16.40% in a formulation that in addition contains 0.8% inhibitor. The degree of blistering, evaluated in accordance with DIN EN ISO 4628-2, was 0 (S0).

[0066] In a comparison of conventionally used mica and hydrophobic, basic filler in formulation in an amount of 16.40% and omitting the use of inhibitors or corrosion-resistant pigment, the hydrophobic, basic filler performed better in this salt spray test.

[0067] The applicant reserves the right to claim all the features disclosed in the application documents as being essential to the invention, provided that said features are novel over the prior art, either individually or in combination. It is furthermore noted that the individual drawings also describe features that may be advantageous in their own right. A person skilled in the art will directly recognise that a specific feature described in a drawing may also be advantageous without adopting further features from this drawing. Furthermore, a person skilled in the art will recognise that advantages may also result from a combination of a plurality of features shown individually or in different drawings.