Process for the production of removable soil- and water-resistant surface coatings

The present invention relates to a process for the production of dirt- and water-repellent flat coatings on articles, hydrophobic particles being applied to the surface of the articles during the coating and thus producing a surface structure with elevations on the surface of the articles, the dirt and water-repellent properties having.

The principle of self-cleaning coatings is well known. In order to achieve a good self-cleaning of a surface, the surface must also have a certain roughness in addition to a very hydrophobic surface. A suitable combination of structure and hydrophobicity makes it possible for even small amounts of moving water to take dirt particles adhering to the surface with them and to clean the surface (WO-A-96/04123; US 3,354,022).

State of the art according to EP-B-0 933 388 is that an aspect ratio of> 1 and a surface energy of less than 20 mN / m is required for such self-cleaning surfaces. The aspect ratio is defined here as the quotient of the height of the structure. The aforementioned criteria are realized in nature, for example in the lotus leaf. The surface of the plant, which is formed from a hydrophobic wax-like material, has elevations that are a few μm apart. Water drops essentially only come into contact with the tips of the elevations. Such water-repellent surfaces are widely described in the literature.

CH-268258 describes a process in which structured surfaces are produced by applying powders such as kaolin, talc, clay or silica gel. The powders are fixed on the surface by oils and resins based on organosilicon compounds (Examples 1 to 5).

EP-A-0 909 747 teaches a method for producing a self-cleaning surface. The surface has hydrophobic elevations with a height of 5 to 200 µm. Such a surface is produced by applying a dispersion of powder particles and an inert material in a siloxane solution and then curing. The structure-forming particles are thus fixed to the substrate by an auxiliary medium.

WO-A-00/58410 comes to the conclusion that it is technically possible to make the surfaces of objects artificially self-cleaning. The surface structures of elevations and depressions required for this have a distance between the elevations of the surface structures in the range from 0.1 to 200 µm and a height of the elevation in the range 0.1 to 100 µm. The materials used for this must consist of hydrophobic polymers or permanently hydrophobized material. Detachment of the particles from the carrier matrix must be prevented.

The use of hydrophobic materials, such as perfluorinated polymers, for the production of hydrophobic surfaces is known. A further development of these surfaces is to structure the surfaces in the µm range to the nm range. No. 5,599,489 discloses a method in which a surface can be given a particularly repellent finish by bombardment with particles of a corresponding size and subsequent perfluorination. Another method describes H.

Saito et al. in "Service Coatings International", 4, 1997, p. 168 ff. Here, particles of fluoropolymers are applied to metal surfaces, with a greatly reduced wettability of the surfaces thus produced against water with a significantly reduced tendency to icing.

The principle is borrowed from nature. Small contact areas reduce Van-der Waal's interaction, which is responsible for the adhesion to flat surfaces with low surface energy. For example, the leaves of the lotus plant are provided with raised areas made of wax, which reduce the contact area with water.

Methods for producing these structured surfaces are also known. In addition to the detailed reproduction of these structures by a master structure in the injection molding or embossing process, processes are also known which use the application of particles to a surface (US Pat. No. 5,599,489).

In recent times, attempts have been made to provide self-cleaning surfaces on textiles as well. It has been found that by applying highly disperse SiO₂ (Aerosils) self-cleaning surfaces can be produced on textiles. The aerosils are integrated with a solvent in the polymer matrix of the textile fiber.

DE-A-101 18 348 describes polymer fibers with self-cleaning surfaces in which the self-cleaning surface by the action of a solvent which has structure-forming particles, dissolving the surface of the polymer fibers by the solvent, adhering the structure-forming particles to the detached surface and removing them of the solvent is obtained. The disadvantage of this method is that when processing the polymer fibers (spinning, knitting, etc.) the structure-forming particles and thus the structure that causes the self-cleaning surface can be damaged or even completely lost under certain circumstances and the self-cleaning effect is also lost.

DE-A-101 18 346 describes textile fabrics with a self-cleaning and water-repellent surface, made up of at least one synthetic and / or natural textile base material A and an artificial, at least partially hydrophobic surface with elevations and depressions made of particles which are free of adhesives, resins or Lacquers are firmly bonded to the base material A, which are obtained by treating the base material A with at least one solvent, which contains the particles undissolved, and removal of the solvent, at least some of the particles being firmly attached to the surface of the base material A, are obtained. The disadvantage of this method, however, is based on a very complex finishing of the textile surfaces. In this process it is necessary that the solvent has to be matched exactly to the base material of the textiles. In the case of garments, however, there are usually mixed fabrics, which makes this coordination even more complicated. If the solvents are not properly matched, parts of the garment may be destroyed. Treatment of the textile surfaces is therefore necessary before tailoring.

All of these coatings have the disadvantage that they are permanently applied to the objects and therefore cannot be easily removed and reapplied if the surface is scratched, discolored or otherwise damaged. In the event of such damage, the object must either be re-treated, elaborately removed from the surface structure or disposed of.

WO-A-00/58410 describes a process for the production of detachable coatings with dirt and water-repellent properties, the same by spraying on hydrophobic alcohols, such as nonacosan-10-diol or alkane diols, such as nonacosan-5,10-diol or waxes getting produced. These coatings are strong mechanical forces such. B. Remove from the objects scratching, brushing or high pressure treatment with water or by treatment with water which contains detergents which dissolve some of the structuring agents. A disadvantage of this is the strong forces that are necessary to mechanically remove the coating, so that there is always the risk that the object itself will be damaged when the coating is removed. Treatment with water containing detergents can also damage the item, depending on the nature of the item.

DE-A-101 35 157 describes a method for coating textiles during a chemical cleaning process in which structure-forming particles are added to the cleaning agent. Relatively aggressive organic solvents, such as e.g. B. Trichlorethylene proposed, the use of which leads to a mechanical anchoring of the particles on the structure of the textiles, which can lead to damage to the object to be coated.

The object of the present invention was therefore to provide a method for producing dirt and water-repellent, flat coatings on objects, in which objects made of sensitive materials can also be provided with a relatively stable coating which can be removed with simple means.

Surprisingly, it was found that by applying suspensions containing hydrophobic particles in a solution of a silicone wax in a volatile siloxane to at least one surface of an object and then removing the volatile siloxane, coatings with dirt and water-repellent properties can be obtained are relatively stable, but can also be removed with simple means.

The present invention therefore relates to a process for the production of detachable, dirt and water-repellent flat coatings on articles, hydrophobic particles being applied to the surface of the articles during the coating and thus a surface producing structure with elevations on the surface of the articles has dirt and water repellent properties, which is characterized by that the hydrophobic particles are suspended in a solution of a silicone wax in a volatile siloxane and this suspension is applied to at least one surface of an object and the volatile siloxane is subsequently removed.

The present invention also relates to objects which are provided on at least one surface with a water- and dirt-repellent coating by a method according to at least one of claims 1 to 7.

The present invention also relates to a non-permanent protective coating with water- and dirt-repellent properties for objects, the protective coating being able to be removed from the object again in a simple manner.

In addition, the subject of the present invention is the use of the method according to one of claims 1 to 7 for coating objects which are exposed to high loads of dirt and water, in particular for the outdoor area, sports area such as ski sports, motor sports , Sailing; for coating textiles such as tents, awnings, umbrellas, tablecloths, convertible tops, technical textiles or work clothes and the use of the method according to one of claims 1 to 7 in impregnation sprays.

The present invention describes a method with which removable, dirt and water-repellent coatings can be produced.

The invention has the advantage that objects of all kinds can be equipped with a dirt and water-repellent, non-permanent layer in a simple manner.

In contrast to methods according to the prior art, the coating according to the invention with a detachable dirt-repellent layer is relatively gentle, since no questionable or aggressive solvents are used and since the coating can be detached, for example mechanically, by rubbing.

The coating produced by means of the method according to the invention is not permanent and is therefore particularly suitable as a protective coating for new objects against soiling, e.g. B. during transport or in the sales rooms.

The process for the production of detachable, dirt and water-repellent flat coatings on objects, wherein during the coating hydrophobic particles are applied to the surface of the objects and thus a surface structure with elevations on the surface of the objects is produced, which has dirt and water-repellent properties is characterized by that hydrophobic particles are suspended in a solution of a silicone wax in a volatile silicone and this suspension is applied to at least one surface of an object and the volatile silicone is subsequently removed.

As volatile silicones, all linear compounds of the general formula (I) and / or cyclic compounds of the general formula (Ia) which are liquid at room temperature are<chemistry id="chem0001" num="0001"><img file="EP1475426A1_D0001.tif" /></chemistry> wherein<dl id="dl0001" compact="compact"><dt>n</dt><dd>is a number from 2 to 10, preferably for the linear compounds 2 to 5 and preferably for the cyclic compounds&gt; 4, especially&gt; 5 (such as D5 = decamethylpentacyclosiloxane) and / or ≥ 6 to about ≥ 8. Cyclic and linear siloxanes can be used in a mixture with one another, but preferably in a mixture with one another.</dd></dl>

All compounds which are liquid at room temperature can be used as silicone waxes, ie have a recrystallization point below room temperature of approximately 20 ° C., preferably &lt;15 ° C., in particular &lt;5 ° C., in particular those of the general formula (II)<chemistry id="chem0002" num="0002"><img file="EP1475426A1_D0002.tif" /></chemistry> in what mean<dl id="dl0002"><dt>R</dt><dd>a hydrocarbon radical, preferably having 10 to 20 carbon atoms,</dd><dt>n</dt><dd>2nd up to 85</dd><dt>m</dt><dd>2nd to 60.</dd></dl>

The suspension can be applied to at least one surface of an object in a manner known to the person skilled in the art. The suspension is preferably applied by dipping the object into the suspension and subsequent dripping or by spraying the suspension onto the object. Surprisingly, particularly durable coatings which are less susceptible to scratching and abrasion, in particular on polymer surfaces, can be produced in particular by applying the suspension by spraying.

During the spraying process, the particles are even more firmly embedded in the existing surface roughness of the polymer matrix due to their kinetic energy. The suspension is preferably sprayed on by means of a spraying device which has a nozzle with a diameter of 0.05 to 2 mm, preferably with a diameter of 0.1 to 0.9 mm. The suspension is preferably sprayed at a pressure of 1 to 5 bar.

The volatile silicone is removed by evaporation or volatilization, and the evaporation or volatilization can be accelerated by using elevated temperatures or by using a vacuum or vacuum.

Particles which can be used are those which have at least one material selected from silicates, minerals, metal oxides, metal powders, silicas, pigments or polymers. The particles can particularly preferably be silicates, doped silicates, minerals, metal oxides, aluminum oxide, silicas or pyrogenic silicates, aerosils or powdered polymers, such as, for. B. spray-dried and agglomerated emulsions or cryomilled PTFE (Teflon). Hydrophobically coated silicas are particularly preferably used as hydrophobic particles.

The hydrophobic properties of the particles may be inherent due to the material used for the particles, such as, for example, in the case of polytetrafluoroethylene (PTFE). However, it is also possible to use hydrophobic particles which, after suitable treatment, have hydrophobic properties, such as. B. treated with at least one compound from the group of alkylsilanes, fluoroalkylsilanes or disilazanes. Particularly suitable particles are hydrophobicized pyrogenic silicas, so-called aerosils. Examples of hydrophobic particles are e.g. B. the Aerosil® R 812S or Aerosil® R 8200.

The surfaces produced by means of the method according to the invention preferably have a wedge angle (circle fitting) for water of&gt; 100 °, preferably&gt; 115 °, particularly preferably&gt; 125 ° and very particularly preferably&gt; 130 °. The circle fitting method with the Krüss device DSA 10 results in lower values ​​in absolute numbers than the classic test method, but enables a better evaluation of the quality of a coating due to the additional dynamic evaluation.

The coatings of the invention can be easily processed by mechanical processing such. B. rubbing, polishing or high-pressure cleaner (water) detach again from the coated object, but adhere so firmly to the substrates that their properties according to the invention are given over a practical period.

The method according to the invention can be used to produce articles which are equipped on at least one surface with a water and dirt-repellent coating. The objects or the surfaces to be coated can be made from a wide variety of substances, such as. B. consist of metal, plastic, polymer, wood, ceramic or glass.

The method according to the invention can also be used in impregnation sprays.

With such sprays z. B. garden furniture, car rims, car paints, showers, tiles, sanitary areas in general, laundry rooms and the like with removable dirt and water repellent coatings.

The method according to the invention and its use are described below by way of example, without any intention that the invention should be restricted thereto.

Test procedure:

Coating of the surfaces:

The surfaces are coated by spraying the suspensions with a full-cone spray nozzle, for example of the GSC-1 type from Spraying-Systems GmbH. For this purpose, a quantity of 1.5 g of the suspension is weighed into a test tube and this is sucked from the nozzle by means of a rubber tube and sprayed onto the surface. The surface is weighed before and after spraying in order to determine the mass of the applied layer thickness.

Determination of the contact angle:

The contact angle was determined using a type DSA 10 from Krüss GmbH. For this purpose, a drop of distilled water with a volume of 7 µl was applied to the surface and this was recorded with a high-speed camera. The evaluation was carried out using software DSA version 1.80.1.2 [HS] using the "circle fitting" method.

Determination of the gloss value:

The gloss value was determined using a device type REFO 3-D from Lange GmbH. For this purpose, the gloss value was measured at three different points on the surface by means of three-angle measurement (20 °, 60 °, 85 °). The mean value from these measurements represents the gloss of the entire surface, where 1 = very high gloss and 6 = matt surface.

Rolling behavior:

The surface slope of the coated substrate was 45 °. 1 = immediate, resistance-free and residue-free unrolling of an applied approx. 500 µl water drop, 6 = spreading of the drop, ie no unrolling effect but evaporation.

Delay in penetration:

1 = no penetration, 6 = no delay, immediate penetration.

Appearance:

Overall sensory impression of the appearance. 1 = the surface appears untreated and unloaded, 6 = both the coating and the load are clearly perceptible, ie they are perceived as disturbing.

Overall grade:

Is the arithmetic mean of the evaluated criteria. The lower the value, the more positive the overall impression.

Execution:

Example 1 (comparison):

According to EP-A-1 153 987, 0.5 g of polyoctadecyl vinyl ether with a molecular weight of approx. 3,000 g / mol (Lutonal® A25) was dissolved in 98.5 g of petroleum spirit (boiling range 90 to 100 ° C.). 1.0 g of a commercially available, hydrophobicized pyrogenic silica with a BET surface area of ​​220 m was added to this solution with intensive stirring²/ g (Aerosil® R 812 S, hereinafter R 812 S) dispersed.

This suspension gave a contact angle of 130 ° and a gloss value of 0.9 at 85 ° on white glazed tiles.

Example 2:

0.5 g of siloxane wax (Tegopren® 6814, hereinafter TP 6814) with a molecular weight of 13,000 g / mol and a recrystallization point of &lt;5 ° C. were dissolved in 98.5 g of decamethylcyclopentasiloxane (D5). 1.0 g of a commercially available, hydrophobicized pyrogenic silica with a BET surface area of ​​220 m was dispersed into this solution with vigorous stirring²/ g, (Aerosil® R 812 S).

This suspension gave a contact angle of 130 ° and a gloss value of 15.0 at 85 ° on white glazed tiles.

Example 3:

0.5 g of siloxane wax (Tegopren® 6814) with a molecular weight of 13,000 g / mol and a recrystallization point of &lt;5 ° C. were dissolved in 98.5 g of decamethylcyclopentasiloxane (D5). 1.0 g of a commercially available, hydrophobicized pyrogenic silica with a BET surface area of ​​160 m was dispersed in this solution with vigorous stirring²/ g, (Aerosil® R 8200, hereinafter referred to as R 8200).

This suspension gave a contact angle of 105 ° on white glazed tiles and a gloss value of 56.1 at 60 °.

Example 4:

0.5 g of siloxane wax (Tegopren® 6814) with a molecular weight of 13,000 g / mol and a recrystallization point of &lt;5 ° C. were dissolved in 97.5 g of decamethylcyclopentasiloxane (D5). 2.0 g of a commercially available, hydrophobicized pyrogenic silica with a BET surface area of ​​220 m were dispersed in this solution with vigorous stirring²/ g, (Aerosil® R 812 S).

This suspension gave a contact angle of 133 ° and a gloss value of 11.7 at 85 ° on white glazed tiles.

Example 5:

0.5 g of siloxane wax (Tegopren® 6814) with a molecular weight of 13,000 g / mol and a recrystallization point of &lt;5 ° C. were dissolved in 97.5 g of decamethylcyclopentasiloxane (D5). 2.0 g of a commercially available, hydrophobicized pyrogenic silica with a BET surface area of ​​160 m were dispersed in this solution with vigorous stirring²/ g, (Aerosil® R 8200).

This suspension gave a contact angle of 106 ° on white glazed tiles and a gloss value of 42.2 at 60 °. <tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="7" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="22.50mm" /><colspec colnum="2" colname="col2" colwidth="22.50mm" /><colspec colnum="3" colname="col3" colwidth="22.50mm" /><colspec colnum="4" colname="col4" colwidth="22.50mm" /><colspec colnum="5" colname="col5" colwidth="22.50mm" /><colspec colnum="6" colname="col6" colwidth="22.50mm" /><colspec colnum="7" colname="col7" colwidth="22.50mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" rowsep="0" align="center"><b>surface</b></entry><entry namest="col2" nameend="col2" rowsep="0" align="center"><b>Assessment criteria</b></entry><entry namest="col3" nameend="col3" align="center"><b>example 1</b></entry><entry namest="col4" nameend="col4" align="center"><b>Example 2</b></entry><entry namest="col5" nameend="col5" align="center"><b>Example 3</b></entry><entry namest="col6" nameend="col6" align="center"><b>Example 4</b></entry><entry namest="col7" nameend="col7" align="center"><b>Example 5</b></entry></row><row><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col2" /><entry namest="col3" nameend="col3" align="left">Petroleum spirit + 0.5% Lutonal A25 + 1.0% R 812 S</entry><entry namest="col4" nameend="col4" align="left">+ 0.5% Tp 6814 + 1.0% R 812 S ad 100% D5</entry><entry namest="col5" nameend="col5" align="left">+ 0.5% Tp 6814 + 1.0% R 8200 ad 100% D5</entry><entry namest="col6" nameend="col6" align="left">+ 0.5% Tp 6814 + 2.0% R 812 S ad 100% D5</entry><entry namest="col7" nameend="col7" align="left">+ 0.5% Tp 6814 + 2.0% R 8200 ad 100% D5</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" morerows="3" align="left"><b>Painted sheet</b></entry><entry namest="col2" nameend="col2" align="left">Rolling behavior of water drops</entry><entry namest="col3" nameend="col3" align="center">2</entry><entry namest="col4" nameend="col4" align="center">1</entry><entry namest="col5" nameend="col5" align="center">4</entry><entry namest="col6" nameend="col6" align="center">1</entry><entry namest="col7" nameend="col7" align="center">2</entry></row><row><entry namest="col2" nameend="col2" align="left">Appearance</entry><entry namest="col3" nameend="col3" align="center">6</entry><entry namest="col4" nameend="col4" align="center">6</entry><entry namest="col5" nameend="col5" align="center">3</entry><entry namest="col6" nameend="col6" align="center">6</entry><entry namest="col7" nameend="col7" align="center">2</entry></row><row><entry namest="col2" nameend="col2" align="left">shine</entry><entry namest="col3" nameend="col3" align="center">6</entry><entry namest="col4" nameend="col4" align="center">6</entry><entry namest="col5" nameend="col5" align="center">3</entry><entry namest="col6" nameend="col6" align="center">6</entry><entry namest="col7" nameend="col7" align="center">3</entry></row><row><entry namest="col2" nameend="col2" align="left"><b>Overall grade</b></entry><entry namest="col3" nameend="col3" align="center"><b>4,7</b></entry><entry namest="col4" nameend="col4" align="center"><b>4,3</b></entry><entry namest="col5" nameend="col5" align="center"><b>3,3</b></entry><entry namest="col6" nameend="col6" align="center"><b>4,3</b></entry><entry namest="col7" nameend="col7" align="center"><b>2,3</b></entry></row><row><entry namest="col1" nameend="col1" morerows="3" align="left"><b>Glazed tile</b></entry><entry namest="col2" nameend="col2" align="left">Rolling behavior of water drops</entry><entry namest="col3" nameend="col3" align="center">2</entry><entry namest="col4" nameend="col4" align="center">1</entry><entry namest="col5" nameend="col5" align="center">4</entry><entry namest="col6" nameend="col6" align="center">1</entry><entry namest="col7" nameend="col7" align="center">3</entry></row><row><entry namest="col2" nameend="col2" align="left">Appearance</entry><entry namest="col3" nameend="col3" align="center">5</entry><entry namest="col4" nameend="col4" align="center">5</entry><entry namest="col5" nameend="col5" align="center">3</entry><entry namest="col6" nameend="col6" align="center">5</entry><entry namest="col7" nameend="col7" align="center">3</entry></row><row><entry namest="col2" nameend="col2" align="left">shine</entry><entry namest="col3" nameend="col3" align="center">6</entry><entry namest="col4" nameend="col4" align="center">6</entry><entry namest="col5" nameend="col5" align="center">2</entry><entry namest="col6" nameend="col6" align="center">6</entry><entry namest="col7" nameend="col7" align="center">3</entry></row><row><entry namest="col2" nameend="col2" align="left"><b>Overall grade</b></entry><entry namest="col3" nameend="col3" align="center"><b>4,3</b></entry><entry namest="col4" nameend="col4" align="center"><b>4,0</b></entry><entry namest="col5" nameend="col5" align="center"><b>3,0</b></entry><entry namest="col6" nameend="col6" align="center"><b>4,0</b></entry><entry namest="col7" nameend="col7" align="center"><b>3,0</b></entry></row><row><entry namest="col1" nameend="col1" morerows="2" align="left"><b>Porcelain stoneware tile</b></entry><entry namest="col2" nameend="col2" align="left">Rolling behavior of water drops</entry><entry namest="col3" nameend="col3" align="center">3</entry><entry namest="col4" nameend="col4" align="center">1</entry><entry namest="col5" nameend="col5" align="center">4</entry><entry namest="col6" nameend="col6" align="center">1</entry><entry namest="col7" nameend="col7" align="center">2</entry></row><row><entry namest="col2" nameend="col2" align="left">Appearance</entry><entry namest="col3" nameend="col3" align="center">5</entry><entry namest="col4" nameend="col4" align="center">4</entry><entry namest="col5" nameend="col5" align="center">1</entry><entry namest="col6" nameend="col6" align="center">4</entry><entry namest="col7" nameend="col7" align="center">2</entry></row><row><entry namest="col2" nameend="col2" align="left"><b>Overall grade</b></entry><entry namest="col3" nameend="col3" align="center"><b>4,0</b></entry><entry namest="col4" nameend="col4" align="center"><b>2,5</b></entry><entry namest="col5" nameend="col5" align="center"><b>2,5</b></entry><entry namest="col6" nameend="col6" align="center"><b>2,5</b></entry><entry namest="col7" nameend="col7" align="center"><b>2,0</b></entry></row><row><entry namest="col1" nameend="col1" morerows="3" align="left"><b>Glass</b></entry><entry namest="col2" nameend="col2" align="left">Rolling behavior of water drops</entry><entry namest="col3" nameend="col3" align="center">4</entry><entry namest="col4" nameend="col4" align="center">1</entry><entry namest="col5" nameend="col5" align="center">4</entry><entry namest="col6" nameend="col6" align="center">1</entry><entry namest="col7" nameend="col7" align="center">2</entry></row><row><entry namest="col2" nameend="col2" align="left">Appearance</entry><entry namest="col3" nameend="col3" align="center">6</entry><entry namest="col4" nameend="col4" align="center">6</entry><entry namest="col5" nameend="col5" align="center">2</entry><entry namest="col6" nameend="col6" align="center">6</entry><entry namest="col7" nameend="col7" align="center">3</entry></row><row><entry namest="col2" nameend="col2" align="left">transparency</entry><entry namest="col3" nameend="col3" align="center">6</entry><entry namest="col4" nameend="col4" align="center">5</entry><entry namest="col5" nameend="col5" align="center">2</entry><entry namest="col6" nameend="col6" align="center">6</entry><entry namest="col7" nameend="col7" align="center">3</entry></row><row><entry namest="col2" nameend="col2" align="left"><b>Overall grade</b></entry><entry namest="col3" nameend="col3" align="center"><b>5,3</b></entry><entry namest="col4" nameend="col4" align="center"><b>4,0</b></entry><entry namest="col5" nameend="col5" align="center"><b>2,7</b></entry><entry namest="col6" nameend="col6" align="center"><b>4,3</b></entry><entry namest="col7" nameend="col7" align="center"><b>2,7</b></entry></row><row><entry namest="col1" nameend="col1" morerows="3" align="left"><b>Leather (natural)</b></entry><entry namest="col2" nameend="col2" align="left">Rolling behavior of water drops</entry><entry namest="col3" nameend="col3" align="center">1</entry><entry namest="col4" nameend="col4" align="center">1</entry><entry namest="col5" nameend="col5" align="center">4</entry><entry namest="col6" nameend="col6" align="center">1</entry><entry namest="col7" nameend="col7" align="center">2</entry></row><row><entry namest="col2" nameend="col2" align="left">Appearance</entry><entry namest="col3" nameend="col3" align="center">6</entry><entry namest="col4" nameend="col4" align="center">3</entry><entry namest="col5" nameend="col5" align="center">2</entry><entry namest="col6" nameend="col6" align="center">5</entry><entry namest="col7" nameend="col7" align="center">1</entry></row><row><entry namest="col2" nameend="col2" align="left">Delay in penetrating water</entry><entry namest="col3" nameend="col3" align="center">4</entry><entry namest="col4" nameend="col4" align="center">3</entry><entry namest="col5" nameend="col5" align="center">4</entry><entry namest="col6" nameend="col6" align="center">2</entry><entry namest="col7" nameend="col7" align="center">3</entry></row><row rowsep="1"><entry namest="col2" nameend="col2" align="left"><b>Overall grade</b></entry><entry namest="col3" nameend="col3" align="center"><b>3,7</b></entry><entry namest="col4" nameend="col4" align="center"><b>2,3</b></entry><entry namest="col5" nameend="col5" align="center"><b>3,3</b></entry><entry namest="col6" nameend="col6" align="center"><b>2,7</b></entry><entry namest="col7" nameend="col7" align="center"><b>2,0</b></entry></row></tbody></tgroup></table></tables>

The table at hand clearly shows that by varying the ratio of Aerosil to adhesion promoter it is possible to produce the most favorable suspension for the respective application. However, the use of an adhesion promoter based on silicone wax shows a significant improvement over the prior art on every tested surface.