Coating of fibruous cement boards

0001The present invention relates to a formulation and a method for coating at least on a water-based binder and / or on a ceramic material based flat panel member according to the preamble of claim 1, a use of the Formulation or the method and a Fiber cement board, coated by means of a formulation resp. a method.

0002Fiber cement panels can be depending on the ambient condition, such as temperature, humidity, etc., deform. Thus, Inappropriate example of a facade Fiber cement panels to deform such that both called curling (lowering the front against Zero line of the undeformed plate), as well as a crowning (Lifting the front relative to the zero line of the unformed plate) can occur. are the consequence uneven wall surfaces, which of the appearance affect facade strong.

0003Typically therefore such plates are at least coated on one side in order to prevent deformation.

0004In practice, it has been shown that by Applying coatings, the plates when stacking each "stick", so it is important that the Coating the requirements for the so-called meets blocking resistance.

0005Besides the blocking resistance and the permanent adhesion must the adhesives or primers with subsequent Adhesive application can be guaranteed.

0006Accordingly, an object of the present Invention, a plate comprising a water-based Binder and / or based on a ceramic Material, in particular fiber cement panels or Clay tiles, to equip such that the initially mentioned required properties can be obtained.

0007According to the invention a formulation and a method for equipping or coating a plate of the above -mentioned type according to the wording of claim 1 and according to Claim 9 proposed.

0008It is proposed that scale on at least one Side of the plate, a coating is applied, wherein for the coating of a formulation is used, consisting of at least two dispersions, wherein the one Dispersion film-forming and blocking resistance including ensuring properties and the other Dispersion components with functional groups containing, which are adapted to enable application of the coating a chemical reaction with components in, where appropriate, other coatings, such as the above-mentioned adhesive or respond with so-called primers.

0009It has been found that it is advantageous to use a to use dispersion, which self- having polymer chains. This results in both a good Film formation obtained in addition a good adhesion to the Ground and sufficient hardness of the coating.

0010In particular, the blocking resistance of the coating can be increased.

0011The other dispersion preferably has components reactive groups, which are suitable, a good Adhesion to adhesives, such as 1K PU construction adhesives, to enable. Accordingly, it is advantageous if the reactive groups of components in the dispersion are suitable for reaction with isocyanate groups, which in the mentioned 1K PU construction adhesives available.

0012The dispersions are advantageously aqueous Dispersions based on acrylic polymer, the polymers are self-crosslinking. It is proposed, for example, an aqueous dispersion based on acrylate-styrene polymer or the use of an epoxy-functionalized Acrylate.

0013However, other-aqueous polymer dispersion conceivable such as dispersions based Polyurethane, silicone, epoxy, etc., such as Silicone acrylate dispersions.

0014Further, it is of course possible, the dispersions film-forming additives and / or adhesion-promoting additives accompanied, as well as defoamers.

0015Also proposed is the use of an aqueous Acrylate dispersion comprising components with reactive Groups such as HO-, thiol, amino, epoxy and / or Episulfide.

0016Preferably, a dispersion with epoxy functionalized Groups proposed.

0017Finally, it is possible, for example for the Improve film formation or the liability, in addition Solvents accompanied by the dispersions.

0018First, the two aqueous for the application of Dispersions in a mixing vessel by means of a Mixing unit, such as a dissolver, such mixed with each other that an at least almost homogeneous Mixture. Subsequently, the mixture of two aqueous dispersions by means of casting, spraying, means of a calender, etc., on one side of the plate applied.

0019Further preferred embodiments of the inventive method are in the dependent Claims mentioned.

0020The method according to the invention are defined particularly suited for coating or finishing of fiber cement panels.

0021Based on the embodiment described below, The invention will be explained in more detail.

0022In the invention, known a Combination of two dispersions, according Embodiment, two water-based Acrylate dispersions are used, which is to be the two type dispersions Setalux 6755 AQ-40 and Setalux 8551 AQ-45 from Akzo Nobel is. When system Setalux 6755 AQ-40 If it is a styrene acrylate polymer dispersion. This dispersion has the following Specifications at:<sl><li>Solids content: 39-41%</li><li>pH: 7.0 - 9.0</li><li>Density [g / cm³] About 1:04</li><li>Flash point:> 65 ° C</li><li>MFT: <10 ° C</li></sl>

0023Further dispersion Setalux 8551 AQ-45 is an epoxy-functionalized Dispersion usually as a of two components in a two-component epoxy-amine-curing Dispersion is used. It has a Solids content 43-46% on a density [g / CM³] 1.05, a flash point> 65 ° C and an epoxy equivalent weight, based on the solids content of 621. These two dispersions are in a Mixing container using a dissolver according to the subsequent formulation intensively at room temperature mixed until a largely homogeneous dispersion has arisen:<tables><table><tgroup cols="2"><tbody><row><entry namest="1" nameend="2">Formulation (GT - 103):</entry></row><row><entry align="left">Setalux 6755 AQ-40</entry><entry align="left">84.0gr</entry></row><row><entry align="left">Dowanol PPh</entry><entry align="left">3.5 gr (film former)</entry></row><row><entry align="left">Drewplus T4201</entry><entry align="left">0.3 gr (defoamers)</entry></row><row><entry align="left">Borchicoll BC 20</entry><entry align="left">12.7 gr (adhesion promoters)</entry></row><row><entry align="left">Setalux 8551 AQ-45</entry><entry align="left"><u>11.0 gr</u></entry></row><row><entry align="left">Total</entry><entry align="left">111.5 gr </entry></row></tbody></tgroup></table></tables>

0024In addition, the dispersions may further additives, contain additives or auxiliaries, such as Pigments, dyes, emulsifiers, pigment dispersing additives, Wetting and surface additives, Antioxidants, Absetzadditive, heat stabilizers, UV absorbers and fillers, catalysts, etc.

0025Subsequently, the thus prepared dispersion, aqueous by means of a calender on the rear side of Fiber cement panels applied. Pretreatment of Fiber cement board is not necessary.

0026The dispersion with the label Setalux 6755 AQ-40 represents primarily the stabilization of the plate towards the crown and the curling sure and good blocking resistance. These features result from particularly characterized by these so-called dispersion contains twice-self-polymer chains, which for the achievement of the above properties is beneficial.

0027The epoxy-functionalized dispersion Setalux 8551 AQ-45 mainly produces a significant improvement in adhesion and a further improvement in Bombierungs- and Shots Lungs behavior safely.

0028The isocyanate-containing prepolymers, For example, a 1K PUR adhesive, which in the Rule for attaching plates to a fiber cement Substructure consisting of aluminum or wood in Structures will be used to respond to the application Adhesive with atmospheric moisture with elimination of CO₂ to an amino group. This can on the one hand with a Isocyanate another prepolymer in the adhesive to a urea react to what the for networking Adhesive leads. On the other hand is on this amino group the interface for a reaction with appropriately chemically reactive groups. Such a group can be an epoxy function, as in the aforementioned dispersion Setalux 8551 AQ-45 available, which with the amino group an addition reaction comes in, and the newly formed Bond adhesion of the dispersion coating on the Fiber cement board to the adhesive ensures. While it is normally between adhesive and back coating a primer is applied, which itself both isocyanate-free and may be isocyanate-containing. But any Solvents and / or plasticizers, which in generally contains an adhesive, can not the dissolve completely crosslinked primer or soften and therefore liable friendly in contact with the Backcoat occur. Experiments with and / or without Primer show in both cases a significant improvement liability, which was attributed to the epoxy functionality in due invention dispersion used is.

0029On the basis of experiments it was clearly demonstrated that using a formulation with the label GT103, ie the combination of the two above-mentioned Acrylate the required demands better can be satisfied as with coatings such as from the Prior known art.

0030For example, was at a fiber cement sheets Formulation administered called GT93, only including the dispersion with the label Setalux 6755 AQ-40 with which an improvement in the stabilization of the Plate can be achieved, as well as an improvement in the Blocking resistance. By contrast, shows a much poorer adhesion to the aforementioned construction adhesive and so-called peel test (= peel test) to check the Adhesion of the adhesive on the back coat showed that the fraction largely along the Interface between adhesive and coating proceeded. in the Contrast, gave a peel test or peel test at Use of the inventively combined dispersion, that the adhesive falls apart (cohesive) So on the Backside coating remains. Interestingly is that an improvement both with use of a is achieved without using a primer or primer.

0031Next pendulum hardnesses were measured in paints a common method to the elasticity and deformability determine the surface. From the bar graph shown in Figure 1, it is apparent that the inventive binder mixture (marked with 6755 + 8551), the pendulum oscillation attenuates at least or the measurement time until the damping of vibrations is on highest. This correlates with a high blocking resistance (Stackability of coated plates, without the Coating being damaged). The measurements were to different points in time and it is performed seen that the pendulum hardness that after one day highest is measured in comparison to the other Versions. This is important, since the coated plates are already directly stacked after coating, and thus are subjected to a load. With respect to the in Figure 1 used abbreviations is as follows added:<sl><li>VR-0012 = from the prior art known and today Used backcoat</li><li>BM-2, and BM-3 = 2 and 3 as binder Comparative measurements,</li><li>BM-2 = Mowilith 7714 and</li><li>BM-3 = Mowilith 7411, both aqueous acrylic dispersions Celanese is.</li></sl>

00321 shows König pendulum hardness (s) at a Wet film thickness of 200 microns, squeegee lift and drying 20min at 80 ° C.

0033Again, a similar picture emerges, as noted above mentioned, the block test by at plates using distinct from usual today backside coatings Avulsions can be seen on the plate. Using, in particular the inventively proposed combined dispersion contrast, derives a Improvement, especially when compared with the currently used Backside coatings by virtually no splintering are noticeable.

0034If the dispersion under example described Using the two acrylate Setalux 6755 AQ-40 and Setalux 8551 AQ-45 is of course, only an example of the present closer to explain the invention. Of course, the Invention in any way on the present invention described combination of the two dispersions limited. Of course, it is possible, any other suitable combinations of dispersions use, much of this is that one of the two Dispersions which together before application are mixed, comprising film-forming character and contains other functional groups to further provided with a Coating or with an adhesive react chemically to can.