Hydrophobized fiber cement product comprising at least one profiled surface

Abstract

A method for improving the hydrophobic properties of a fiber cement product, is provided. The method comprises the steps of providing a fiber cement product comprising at least one profiled surface, applying a water-free silane-based liquid to the at least one profiled surface, and allowing said water-free silane-based liquid to penetrate into the fiber cement product.

Claims

1. A method for imparting the hydrophobic properties to a fiber cement plate said method comprising the steps of: providing a green fiber cement plate using a Hatschek process; curing said green fiber cement plate; milling at least one surface of said fiber cement plate after curing of the green fiber cement plate to provide several grooves; applying a water-free silane-based liquid comprising at least 50% w of silanes of the formula SiR.sub.4, where each of the 4 R-groups is independently an organic group with three of the R-groups selected from ethoxy or methoxy groups and the fourth R-group being a branched or linear hydrocarbon chain, to the at least one profiled surface; and allowing said water-free silane-based liquid to penetrate the fiber cement plate without leaving visual traces, wherein the branched or linear hydrocarbon chain is an octyl, isobutyl or methyl group.

2. A method according to claim 1, wherein said water-free silane-based liquid is a solvent-free silane-based liquid.

3. A method according to claim 1, wherein the water-free silane-based liquid applied to the at least one profiled surface is in an amount of less than 150 g/m.sup.2, and more than 10 g/m.sup.2.

4. A method according to claim 1, wherein the profiled surface comprises a plurality of grooves being equally distributed over said surface, said grooves all having a uniform direction and a uniform depth.

5. A method according to claim 4, wherein said grooves have a flat bottom, two flanks and a trapezoidal cross section in a plane parallel to a recess width (W) and perpendicular to the flat bottom of the groove, the angles between the bottom and each of said flanks is in the range of 90 to about 180.

6. A fiber cement product according to claim 1, wherein the fiber cement product is an autoclave cured fiber cement product.

7. A method according to claim 1, wherein applying said water-free silane-based liquid is done by spraying said water-free silane-based liquid to the profiled surface.

8. A method according to claim 1, wherein applying said water-free silane-based liquid is done by brushing or rolling said water-free silane-based liquid to the profiled surface.

9. A method according to claim 1, wherein the green fiber cement plate is cured using autoclave curing.

10. A fiber cement product obtained according to claim 1.

11. A fiber cement product comprising at least one profiled surface, said fiber cement product comprising a porous fiber cement matrix along said at least one profiled surface, wherein a water-free silane-based hydrophobic agent, originating from a water-free silane-based liquid comprising at least 50% w of silanes of the formula SiR.sub.4, where each of the 4 R-groups is independently an organic group with three of the R-groups selected from ethoxy or methoxy groups and the fourth R-group being an octyl, isobutyl or methyl group, is present in the pores of said matrix along said at least one profiled surface, and said profiled surface comprises sunk parts or surfaces, delimited by flanks having an angle between the sunk surface and the flank in the range of 90 to about 180, wherein the profiled surface is free of silane and siloxane residue.

12. A fiber cement product according to claim 11, wherein said at least one profiled surface (102) comprises sunken surfaces (110) with flanks (126, 128) inclined to a bottom (124) of each sunken surface (110) at an angle (a) more than 90 and less than 180.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1a is schematically a top-view of a profiled fiber cement product, having one post-curing profiled surface, according to the invention.

(2) FIG. 1b is schematically a side-view of a part of this profiled fiber cement product of FIG. 1a, having one post-curing profiled surface, according to the invention.

(3) FIG. 2 is a schematically view of a process to improve the hydrophobic properties of a profiled fiber cement product, having one post-curing profiled surface, according to the invention

(4) The same reference signs refer to the same, similar or analogous elements in the different figures.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(5) The present invention will be described with respect to particular embodiments.

(6) It is to be noticed that the term comprising, used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, steps or components as referred to, but does not preclude the presence or addition of one or more other features, steps or components, or groups thereof. Thus, the scope of the expression a device comprising means A and B should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

(7) Throughout this specification, reference to one embodiment or an embodiment are made. Such references indicate that a particular feature, described in relation to the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases in one embodiment or in an embodiment in various places throughout this specification are not necessarily all referring to the same embodiment, though they could. Furthermore, the particular features or characteristics may be combined in any suitable manner in one or more embodiments, as would be apparent to one of ordinary skill in the art.

(8) When reference is made to a range, unless otherwise specified, the range is to be understood inclusive.

(9) The fiber cement product, being a fiber cement plate 100 in FIG. 1, comprises one profiled surface 102, provided by milling of the trapezoid like grooves 110 after the fiber cement plate 100 was cured in an autoclave. The cured fiber cement product before milling is obtainable from Eternit NV as EQUITONE [Tectiva].

(10) After having been milled using appropriate milling tools, the profiled surface 102 is provided with an hydrophobation agent being water-free silane-based liquids. The used liquids are set out in table 1. Hydrophobation agents used in test 4 to 9 are water-free silane-based liquids, i.e. according to a method of the present invention. Hydrophobation agents in test 4, 6, 7 and 8 are also solvent-free.

(11) In each case, this product is applied by spraying the liquid to the profiled surface. The profiled surface has a width E of 1.22 m and a height L of 2.5 m, resulting in a surface of 3.05 m.sup.2. The amount of liquid, per such surface unit of the profiled surface was 80 g/m.sup.2.

(12) TABLE-US-00001 TABLE 1 Hydrophobation agent # W % active test Water/ Active ingredient in # Product name solvent born ingredient(s) liquid applied 1 DC520 .sup.1 Water born Silane & 16 siloxane 2 DC520 + Water born Silane & 16 IE6682 .sup.1 siloxane 3 IE6682 .sup.1 Water born silane 16 4 Z6341 .sup.1 Waterfree & silane 100 solventfree 5 Funcosil Solvent born Silane & 7 SNL .sup.2 siloxane 6 Protectosil Waterfree & silane 100 BHN .sup.3 solventfree 7 Protectosil Waterfree & silane 100 BHN .sup.3 solventfree 8 Protectosil Waterfree & silane 100 100NK .sup.3 solventfree 9 Z6689/MR2404 .sup.1 Solvent born silane 7.5 .sup.1 available from Dow Corning; .sup.2 available from Remmers .sup.3 available from Demula/Evonik

(13) After having allowed the liquid to penetrate into the profiled surface, the liquid has penetrated into the surface up to an average depth D, as such providing a zone 120 in which the hydrophobation agent is present in the porous fiber cement matrix.

(14) The profiled surfaces are tested on hydrophobicity using the RILEM Test No 11.4 in horizontal application. Also the presence of white residue of the hydrophobation agent was noted (yes or no), and the beading effect of the hydrophobation agent was characterized using a ranking of 1 (water droplets are either soaked up by the surface or remain present as droplets with contact angle of 90 or less between surface and droplet) to 5 (droplets remain on surface as beads, the contact angle being substantially 180). The results are set out in table 2.

(15) The contact angle between a surface Sx and the outer surface of a droplet is the angle between the tangent, at the contact point between surface Sx and the droplet surface, of the curve obtained by making a section of the outer surface of the droplet and a plane perpendicular to the surface Sx, the angle being the angle oriented towards the droplet volume.

(16) TABLE-US-00002 TABLE 2 results Rilem test White residue Beading; visual test after 48 h present? assessment # (ml) (y/n) (1 to 5) 1 0.3 Y 4 2 0.4 Y 3 3 0.45 Y 2 4 0.23 N 4 5 0.35 N 4 6 0.28 N 3 7 0.28 N 2 8 0.3 N 5 9 0.4 N 5

(17) As is noticeable, the tests 4 to 9, using a water-free, silane based hydrophobation agent, no white residue of the hydrophobation agent is left.

(18) As can be seen in FIGS. 1a and 1b, the profile is a step-wave profile 122 having trapezoid like grooves 110 with a recess depth R of 2 mm, a top width T of 8 mm and a recess width W of 12 mm. The total thickness A of the plate 100 is 10 mm, and a remaining thickness B at the lower surface or bottom 124 of the groove of 8 mm. The inclination angle between the bottom 124 and each of the flanks 126 and 128 is 110, thus providing slopes with a slope width S.

(19) A schematic view of the method to provide the fiber cement products according to the invention is shown in FIG. 2.

(20) The method for improving the hydrophobic properties of a fiber cement product, comprises first the step 200 of providing a green fiber cement product, preferably a plate. This may be done by a Hatscheck process.

(21) This green plate may optionally be compresses in the optional step 210, after which the green fiber cement plate is cured by means of air curing or autoclave curing in step 220.

(22) In a next step 230, the cured product is given a profiled surface by e.g. milling. Thereafter in a next step 240 water-free, silane based hydrophobation agents are applied, e.g. by spraying to the at least one profiled surface.

(23) The applies hydrophobation agent is allowed to penetrate in step 250 and a product according to the present invention is obtained. The hydrophobation agent is penetrated through the surface into the pores of the fiber cement matrix of the fiber cement product. At the surface, no visual residue of the hydrophobation agent is left.

(24) It is to be understood that although preferred embodiments and/or materials have been discussed for providing embodiments according to the present invention, various modifications or changes may be made without departing from the scope and spirit of this invention.