EP1838646A1

EP1838646A1 - Coating system

Info

Publication number: EP1838646A1
Application number: EP06706158A
Authority: EP
Inventors: Martin Schichtel; Jörg JODLAUK
Original assignee: Viking Advanced Materials GmbH
Current assignee: Viking Advanced Materials GmbH
Priority date: 2004-12-31
Filing date: 2006-01-02
Publication date: 2007-10-03
Also published as: KR20070107673A; CN101133004A; CA2592864A1; US20160083588A1; JP2008526658A; US20090283014A1; WO2006070021A1

Abstract

The invention relates to a coating system, particularly for coating concrete, concrete-like, mineral and/or ceramic substrates. The coating system contains a binder, which is at least partially comprised of an inorganic phosphatic binder, and contains fillers. The fillers contain nanoscale particles with an average particle diameter d50 of less than 300 nm.

Description

coating system

The invention relates to a coating system, in particular for coating vo¬n bricks and facades, which comprises a binder system based on an inorganic phosphatic binder and fillers.

Such coating systems are known from the prior art. For example, WO 01/87798 A2 describes a wear-resistant composite protective layer which is produced via chemical bonding using monoaluminum phosphate (Al (HsPO 4) 3). This process involves the preparation of a hydroxide ceramic which is cured or sintered after phosphating by heat treatment at between 200 and 1200 ^° C.

WO 85/05352 describes an example of a joining layer between ceramic and metallic materials which is reinforced by a monoaluminum phosphate generator. Curing takes place in the course of the sintering process between 1000 and 1250 ⁰ C.

DE 600 02 364 T2 describes an aluminum-wettable protective layer for carbon components, which is intended to protect a substrate against corrosive attack. The layer contains particles of metal oxides or partially oxidized metals in a dried colloidal carrier, which may contain, inter alia, monoaluminum phosphate. By contact with molten aluminum is a curing of the ceramic layer.

US Pat. No. 3,775,318 describes mixtures of alkaline earth fluorides which are bound to form a protective layer by means of an aluminum phosphate binder present in an inorganic solvent. After the appropriate protective layer has been applied, curing takes place in the temperature range above 100 ^° C. for several hours under ambient atmosphere.

The inorganic phosphates used as binder phase in the described prior art are crosslinked via thermally activated reactions. This requires a temperature treatment, which often takes several hours to harden the protective layer dimensionally stable.

The object of the invention is to provide a Be layering system based on an inorganic phosphatic binder as a binder phase, which can be cured dimensionally stable at lower temperatures and / or in less time.

Another object of the invention is to provide a coating system based on an inorganic phosphatic binder as a binder phase, which is the production of protective layers with improved properties compared to the prior art, for. B. improved adhesion, increased corrosion resistance "or improved weather resistance to specify. This object is achieved by a coating system having the features of patent claim 1. Preferred embodiments and further developments of the invention are specified in the subclaims.

The invention provides a coating system with a binder at least partially composed of a phosphatic binder and fillers. A binder in the context of the present invention is the non-volatile portion of a coating material without pigment and filler, but including any existing plasticizer, driers and other nonvolatile Hilf substances. The binder combines fillers or pigment particles with each other and with the substrate (substrate).

For the purposes of the present invention, the term "coating system" is intended to encompass both the starting material for the production of a coating (formulation for application) and the hardened layer In other words, the coating system of the present invention comprises an aqueous or powdery material which is suitable for producing the corresponding Layer is suitable, and the relevant layer after the application and curing of the material.

A filler in the context of the present invention is a (usually powdery) in the application medium practically insoluble substance that. z. B. to increase the volume (cheapening), to achieve or improve technical effects and properties of the protective layer and / or influencing the Processing properties can be used. According to the invention, at least some of the fillers consist of nanoscale particles with an average particle diameter d50 of less than or equal to 300 nm.

The inventors of the present invention have found that the addition of nano-scale particles can significantly accelerate the cure of phosphatic binder phases. In this way, coating systems can be provided which can be cured even at room temperature.

The mean particle diameter d50 of the nanoscale particles is preferably 250 nm or less. Particular preference is given to nanoparticles in the size range of a d50 value below 200 nm. Particularly favorable results can be achieved with nanoparticles in the size range of a d50 value below 100 nm. Very good results can be achieved when using nanoparticles in the size range of a d50 value below 60 nm, and the results are optimal when using nanoparticles in the size range below 20 nm.

The d50 characteristic value commonly used for characterizing the grain size in the relevant technology is defined by the probability theory and states that 50% of the measured particles are smaller than the corresponding measured value. It is based on a standard statistical description of the size distribution of the particles in a disperse system of different particle sizes, cf. "Practice Guide Particle Size Characterization", A. Jillavenkatesa, SJ Dapkunas, Lin-Sein H. Lum, National Institue of Standards and Technolgy, Special Publication 960-1, January 2001, pp. 129-133.

In practice, the d50 value can be determined by various methods, i.a. a. Laser diffraction based on ISO 13320-1, 1999-11 edition; Particle size analysis by photon correlation spectroscopy DIN ISO 13321, Edition 2004-10; Particle size analysis by dispersion methods for powders in liquids according to ISO 14887, Edition 2000-09; or measured by particle size analysis dispersion methods for powders in liquids in accordance with BS ISO 14887, Edition 2001-03-15. Due to the standardization of the corresponding procedures, it is ensured that the same measured value is achieved with the different methods.

By adding the nanoparticles, selected binder systems of the invention based on a phosphate binder phase can be converted into the dust-dry state in drying times of 30 seconds to about 60 minutes, and curing can be achieved at drying times of up to 8 hours at room temperature. The addition of the nanoparticles makes thermal activation of the condensation processes unnecessary in many cases. Without reliable knowledge, it is assumed that the high specific surface of the nanoparticles favors the condensation reaction of the phosphates, possibly even "catalyzed".

The inventors have found that the minimum content of nanoparticles is not a critical factor of the compositions represents and even in compositions with low levels of 0.2 to 0.5 wt .-% of nanoparticles, based on the solid phase, the effect according to the invention can be achieved.

In addition to the accelerated curing, the compositions according to the invention, which are adapted to the particular application, have additional advantages in terms of freeze-thaw cycling, chemical resistance, adhesive strength and weathering stability in general.

The coating system according to the invention also makes it possible to produce protective layers which, as a diffusion barrier for, for example, moisture or aggressive compounds (corrosion protection), provide significantly improved results compared to conventional compositions. Because of this, it can be concluded that not only the reaction kinetics of the curing mechanism but also those with microstructure of the resulting layer based on phosphate binder phases can be substantially improved by the addition of nanoparticles according to the invention.

Further advantages gives the coating system of the invention in terms of concrete or mineral substrate due to significantly favored adhesion. Depending on the application, this can be attributed to an interaction of the nanoparticles with the phosphatic binder in combination with substrate components such as, for example, CSH (calcium silicate hydrate). This results in protective layers with significantly improved adhesion and compared to the known systems significantly increased weather resistance.

Basically, the coating system according to the invention for the coating of any substrates (substrates) is suitable, but especially concrete, concrete-like, mineral and ceramic substrates. In practice, it is therefore predestined especially for roof tiles and facades.

According to the invention, the phosphatic binder consists of at least one phosphate selected from the group of alkali polyphosphates, polymer alkyiphosphates, silicophosphates, monoaluminium phosphate, boron phosphate, magnesium sodium phosphate, alkali silicophosphate, phosphate glass, zinc phosphates, magnesium phosphates, calcium phosphates, titanium phosphates, chromium phosphates, iron phosphates and manganese phosphates.

Preferably, monoaluminum phosphate is used, with a content of 90%, based on the binder, gives particularly good results. It is advantageous to use the monoaluminum phosphate (MAP) as a 50- to 60% aqueous solution.

The nanoscale particles used are preferably compounds of an oxide and / or hydroxide from the group consisting of aluminum, titanium, zinc, tin, zirconium, silicon, cerium and magnesium and mixtures of these compounds. In addition, the nanoscale particles may also comprise one or more compounds from the group silicon carbide, titanium and tungsten carbide and / or the corresponding nitrides.

To optimize the binder system, this may be present as an aqueous solution into which additionally at least one sol has been introduced from the group of acid-stabilized silica sols, aluminum sols, zirconols, titanium dioxide sols, bismuth sols and tin oxide sols.

However, the nature and composition of the nanoparticles used is not limited to these compounds and it may other familiar to those skilled in nanoparticles, which are available via the usual procedure, such. As sol-gel routes, etc., were used.

The composition of the other fillers used depends primarily on the desired application and is adjusted accordingly. As additional solids, the fillers in addition to the nanoparticles, for example, one or more oxides from the group quartz, cristobalite, alumina, zirconia and titanium dioxide include. Good results can be achieved if the d50 value of these compounds is in the range of 500 nm to 500 μm, preferably in the range of 500 nm to 10 μm.

By adding suitable fillers, such. As dyes, pigments, dusting phases, etc., the coating system according to the invention can be functionalized within wide limits. As further examples of functional fillers (effect substances) can Fillers are used which are photocatalytically active, have a hydrophobic and / or oleophobic effect and / or stop bacterial contamination of the surface by radiation. In addition, they may have a heat-insulating and / or sound-insulating effect.

In addition, non-oxidic compounds can also be used as fillers. For example, silicon carbide, aluminum nitride, boron carbide, boron nitride, titanium nitride, titanium carbide, tungsten carbide or mixed carbides can be mentioned here. Preferred d50 values of the non-oxidic compounds are in the range between 700 nm and 60 μm. Good results can be achieved in particular when using a d50 value of the non-nonoxide fillers in the range of 1 .mu.m to 12 .mu.m.

In addition, silicatic raw materials, for example from the group of clay, kaolins and clays, preferably having a d 50 value <70 μm, can be used as fillers in addition to the nanoparticles. Improved results are obtained when using a d50 value of the siliceous raw materials in the range between 4 μm and 45 μm. Other glasses or vitreous materials and / or metals may be used.

In principle, the nanoscale particles can be distributed homogeneously in the binder matrix. For cost reasons, it may be useful to distribute the nanoscale particles inhomogeneous in the binder matrix by increasing the concentration of nanoscale particles in the surface of the other fillers. This can be done, for example, by a targeted Be layering of the other fillers with the nanoparticles before mixing the binder phase can be realized. In this case, the nanoscale particles can bind to the surface of the other fillers by chemical and / or physical coupling. For example, a chemical coupling between the nanoparticles and the surfaces of the fillers can be achieved by means of lactic acid.

Advantageously, the water content of aqueous compositions of the invention

Coating system in the range between 15 and 35% by weight. Too high a water content can shift the reaction equilibrium unfavorably, so that there is no reaction. If the water content is too low, the reaction may start too early, which reduces the potlife accordingly.

In the following, preferred embodiments and particular variants of the coating system according to the invention will be described with reference to the figure.

FIG. 1 shows the dependence of the solidification on the particle size used for a composition of exemplary embodiment 1.

In all cases of the embodiments, the coating system was applied to concrete. The application was preferably carried out by spraying (0.8 mm nozzle, 1.8 bar pressure.) The set dry film thickness was in the range between 40 μm and 60 μm, but can also be varied within wide limits Application methods such as brushing, rolling, spin-coating, flooding, dipping or bells can be carried out analogously.

A first embodiment has the following composition in weight percent:

30.0% monoaluminum phosphate

1.6% ammonium acetate 15.0% silica sol 8-10 nm

3.4% lithium acetate 15.0% aluminum oxide 15 nm 20.0% dolomite 10.0% barium sulfate

5.0% titanyl sulfate

As nanoparticles, a mixture of silica sol having a d 50 value of 8-10 nm and alumina having a d 50 value of 15 nm was used here.

This acid composition enables excellent pot life (> 6 months) in conjunction with very good industrial performance. The time to dust drying after application is 10 to 60 seconds. The resulting layer has after drying a high abrasion resistance of PEI = 4, acc. DIN EN ISO 10545 Part 7, on.

This embodiment revealed more than 300 cycles of corrosion resistance. ISO 16151. Figure 1 shows the solidification in percent, with a solidification of 100% indicates the complete transition of a coated paint from the liquid to the solid state, see. Lackformulierungen and paint formulation, B. Müller, U. Poth, Vincentz Verlag, 2003, p. 23. The graph shows that at grain sizes of the nanoparticles in the range of a d50 value greater than 350 to 1000 nm, the solidification achieved with maximum values of 20% is very low.

With decreasing grain size diameter below 350 nm, the degree of solidification increases sharply with decreasing grain size. It already reaches a value of 50% at a particle size of 300 nm and increases by a further 25% at 200 nm to 75%. The values of 80%, 85% and 90% are achieved at 160, 100 and 50 nm, respectively. Complete solidification of the coating to 100% can be achieved with a particle size of 15 nm. The solidification value shown in FIG. 1 was measured after a service life of 8 hours.

As this exemplary embodiment demonstrates, the use of nanoscale aluminum oxide in conjunction with monoaluminum phosphate as binder phase is particularly advantageous since, given a given composition of the coating, material characteristics are achieved which can not be achieved without nanoscale material with the same composition.

A second embodiment of the present invention has the following composition in weight percent: 25.0% lithium water glass 10.0% monoethanolamine 22.0% basic stabilized MAP 10.0% acetic acid 28.0% n-SiO ₂ 5.0% zinc phosphate

In this composition, amorphous Si02 was used as the nanoscale material, with the d50 of the material being 8nm. This basic composition makes it possible to form slightly porous layers (porosity about 6%), which allows penetration of gases and water vapor due to small pore diameters, but blocks liquids (eg water droplets).

Table 1 shows a third embodiment in which five different compositions were prepared which differed in their content of nanoscale material. More specifically, nanoscale alumina (d50 value of 12 nm) was used at levels between 0.5 and 15.02 wt%. The other fillers talcum, calcium bentonite, aluminum borate, spinel black, SiC and mica were added as further fillers and were not present as nanoscale material. The granule size for the fillers was 12 μm (d50) for talc, 5 μm (d50) for calcium bentonite, 30 μm (d50) for aluminum borate, 4 to 10 μm (d50) for spinel black and 10 μm (d50) for SiC. Table 1

Together Composition Together Composition 1-set-up 2-set 3-set 4-set 5

MAP 64,32 64,32 64,32 64,32 64,32

N-Al ₂ O ₃ 0.50 1.25 4.02 10.02 15.02

talc

(Phyllosilicate) 2.25 1.26 1.26 1.26 0.76

Calcium bentonite 3.26 3.26 1.26 1.26 0.76

Aluminum borate 0.5 0.5 0.5 0.5 0.5

Spinel black

(Al-Mg mixed oxide) 11.56 11.56 11.56 9.56 7.56

Malonic acid 1.01 1.01 1.01 1.01 1.00

SiC 14.07 14.07 14.07 10.07 9.07

mica

(Phyllosilicate) 2.53 2.77 2.01 2.00 1.01

For the inventive compositions 1 to 5 shown in Table 1, Tables 2 and 3 show the GT / TT values as a function of the content of nanoparticles or the solidification as a function of the content of nanoparticles. The comparative example designates a corresponding composition without nanoparticles, in which instead of N-Al 2 O 3, an aluminum oxide with a d 50 value of 10 μm was used.

The cross-cut adhesion (GT characteristic) is determined according to DIN 53151. GT = 0 indicates a perfectly smooth cut surface with no part of the coating chipped off. GT = 1 denotes a state in which small chips of the coating have flaked off at the intersections of the grid lines, the chipped area corresponding to approximately 5% of the sections of the grid. GT = 2 denotes a state in which the coating along the Cut edges and / or the intersections flattened area, corresponding to about 15% of the area of the cuts. GT = 3 denotes a state in which the coating has flaked along the cut edges and in the bordered areas, corresponding to about 33% of the area.

In the so-called "tape test" a Tesastreifen is glued over the cut grid and pulled off abruptly. A rating TT = 0 corresponds to no replacement of the coating. TT = 1 indicates a slight detachment along the cut edges and TT = 9 indicates complete detachment, even in the event that the sample has passed the GT test without detachment.

The GT / TT values shown in Table 2 show that even the addition of 0.5% by weight of nanoparticles can significantly improve both the GT value of 4 to 1 and the TT value of 7 to 2. In both cases, a significantly lower tendency to detach the coating results. The characteristics of GT = 1 and TT = 2 obtained in Composition 1 are suitable for practical application of the respective layers.

Table 2

GT / TT values as a function of the content of nanoparticles

The solidification values shown in Table 3 as a function of the content of the nanoparticles also show that by adding 0.5% by weight of Al 2 O 3 in the form of nanoparticles, the service life required for 100% solidification at room temperature increases from> 24 to> 16 by approximately 33%. can be reduced. As the content of nanoscale material increases, the necessary solidification time further decreases. At a content of 15.02% by weight of nanoparticles, solidification can already be achieved in 1 to 2 hours.

Table 3

Solidification depending on the content of nanoparticles

From the results of Tables 1 to 3 it can be seen that even small amounts of nanoparticles in the range of 0.5 wt .-% are sufficient to achieve the effect according to the invention, which is in this embodiment 3 additionally in an improved adhesive strength of the protective layer ,

In addition, additional tests have shown that even at levels 0.1 to 0.2 wt .-% in many applications increased adhesive strength of the resulting protective layer can be achieved.

From the results it follows that not only the curing by the addition of the nanoparticles can be significantly promoted, but also that the invention can provide coatings which are markedly improved in their adhesive strength.

The invention is not limited to the compositions shown above and basically includes any form of application of phosphatic binder phases in conjunction with nanoparticles, which in many cases no longer requires the condensation of the phosphates to be thermally activated and the crosslinking can take place in a much shorter time. In addition, the addition of nanoparticles changes the microstructure of the protective layer, resulting in a significant improvement in adhesion, corrosion resistance, chemical resistance, frost resistance and UV stability.

As an example in Table 4 is a comparison between the freeze-thaw cycling in accordance with DIN 52104, the chemical resistance according to DIN EN ISO 10545, the frost resistance according to DIN EN ISO 10545, UV stability and adhesion after cross-hatching / tape test in accordance with DIN 53151 for the composition of Example 2 compared to a comparative example without nanoparticles, in which the mean particle size of the SiO 2 was 5 μm. Table 4

Comparison of selected properties of the embodiment 2 vs. Comparative Example from the prior art

* Cross-cut / tape test

The results obtained clearly show that the addition of nanoscale particles can improve the freeze-thaw cycling, chemical resistance, frost resistance and UV stability.

Claims

claims

1. coating system, in particular for the coating of concrete, concrete-like, mineral and / or ceramic substrates, comprising a binder, which consists at least partially of an inorganic phosphatic binder, and fillers, characterized in that the fillers nano-scale particles having a medium

Particle diameter d50 smaller than 300 nm include.

2. Coating system according to claim 1, characterized in that the mean particle diameter d50 of the nanoscale particles is below 100 nm.

3. Coating system according to claim 1 or 2, characterized in that the phosphatic binder system at least one phosphate from the group Alkalipolyphosphate, Polymeralkaliphosphate, silicophosphates, monoaluminum phosphate, boron phosphate, magnesium sodium phosphate, alkali silicophosphate, phosphate glass, zinc phosphates, magnesium phosphates, calcium phosphates, titanium phosphates, chromium phosphates, iron phosphates and Manganese phosphate includes.

4. Coating system according to one of the preceding claims, characterized in that the phosphatic binder consists essentially of an aluminum phosphate.

5. Coating system according to one of the preceding claims, characterized in that the nanoscale particles comprise at least one oxide and / or hydroxide from the group aluminum, titanium, zinc, tin, zirconium, silicon, cerium and magnesium.

6. Coating system according to one of the preceding claims, characterized in that the nanoscale particles comprise at least one compound from the group of silicon carbide, titanium and tungsten carbide.

7. Coating system according to one of the preceding claims, characterized in that the nanoscale particles comprise at least one compound selected from the group silicon nitride, titanium and tungsten nitride.

8. Coating system according to one of the preceding claims, characterized in that the inorganic binder system consists of more than 90% of monoaluminum phosphate.

9. Coating system according to one of the preceding claims, characterized in that the organic binder system consists essentially of a 50-60% aqueous MAP solution.

10. Coating system according to one of the preceding claims, characterized in that the Be layering system consists of an aqueous solution and additionally comprises at least one sol from the group of acid-stabilized silica sols, aluminum sols, zirconium sols, Titandioxidsole, bismuth sols and Zinnoxidsole.

11. Coating system according to one of the preceding claims, characterized in that the fillers as an additional solid in addition to the nanoscale particles at least one oxide from the group quartz, cristobalite, alumina, zirconium oxide and titanium dioxide, having a d50 value of 500 nm to 500 microns ,

12. Coating system according to claim 11, characterized in that the d50 value of the oxides is 500 nm-10 μm.

13. Coating system according to one of the preceding claims, characterized in that the fillers as additional solid in addition to the nanoscale particles at least one non-oxide from the group silicon carbide, aluminum nitride, boron carbide, boron nitride, titanium nitride, titanium carbide, tungsten carbide or mixed carbides, mixed nitrides or carbonitrides thereof having a d50 value of in the range of 500 nm to 60 microns.

14. Coating system according to claim 12, characterized in that the d 50 value of the non-oxides in the range 500 nm - 12 microns.

15. Coating system according to one of the preceding claims, characterized in that the fillers in addition to the nanoscale particles as an additional component at least one silicate raw material from the group clay, kaolins and clays with a d50 value <70 microns.

16. Coating system according to claim 14, characterized in that the d 50 value of the silicate raw materials in the range 8 microns - 45 microns.

17. Coating system according to one of the preceding claims, characterized in that the nanoscale particles are homogeneously distributed in the binder matrix.

18. Coating system according to one of the preceding claims, characterized in that the nanoscale particles are distributed inhomogeneous in the binder matrix, wherein a concentration of the nanoscale particles in the region of the surface of the further fillers is present.

19. Coating system according to one of the preceding claims, characterized in that the nanoscale particles are fixed by chemical and / or physical coupling to the surface of the other fillers.

20. Coating system according to one of the preceding claims, characterized in that the water content of the coating system before coating is less than 45 wt .-%.