Fiber cement product comprising at least one profiled surface

Abstract

A method for improving the hydrophobic properties of a fiber cement product, said method comprising the steps of: providing a fiber cement product comprising at least one profiled surface; applying a hydrophobation agent to the at least one profiled surface; wherein the obtained fiber cement product has a water take up of less than 1.5 mL after 48 hours as measured by the RILEM Test No 11.4 in horizontal application.

Claims

1. A method for increasing hydrophobicity of a fiber cement product, said method comprising the steps of providing a fiber cement product comprising at least one profiled surface where grooves are milled, said grooves each having a depth in the range 0.15 mm to 1 mm and a maximum width at a bottom of the groove in the range 2 mm to 20 mm; and applying a hydrophobation agent to the at least one profiled surface to obtain fiber cement product having a water take up of less than 1.5 mL after 48 hours as measured by the RILEM Test No 11.4 in horizontal application, wherein the hydrophobation agent is water free and the combination of a silane-based liquid comprising at least one silane of the formula SiR.sub.4 with each of the four R-groups independently being an organic group, three of the R-groups being selected from ethoxy or methoxy groups and the fourth R-group being a branched or linear hydrocarbon chain of an octyl, isobutyl or methyl group, and at least one oligomer siloxane of the formula H(R.sub.2SiO).sub.nOH with each of the R-groups independently being an organic group; and allowing said silane-based liquid to penetrate the at least one profiled surface without leaving visual traces.

2. A method according to claim 1, wherein the water take up is less than 1 mL per 48 hours.

3. A method according to claim 1, wherein the fiber cement product is a fiber cement plate.

4. A method according to claim 1, wherein the grooves are equally distributed over said surface, said grooves all have a uniform direction and a uniform depth.

5. A method according to claim 1, wherein each said groove has a trapezoid cross section in a section according to a plane perpendicular to the direction of the groove, said groove having a flat bottom and two flanks, the angles between the bottom and each of said flanks is in the range of 90° to about 180.

6. A method according to claim 1, comprising the step of autoclave curing the fiber cement product.

7. A method according to claim 1, comprising the step of air curing the fiber cement product.

8. A method according to claim 1, wherein the provision of a fiber cement product comprising at least one profiled surface comprises providing a green fiber cement plate using a Hatschek process, and profiling at least one surface of said fiber cement plate.

9. A method according to claim 8, wherein the green fiber cement plate is cured using autoclave curing.

10. A method according to claim 8, wherein the green fiber cement plate is cured using air curing.

11. A method according to claim 8, wherein the at least one profiled surface is provided by profiling a surface of the green fiber cement product.

12. A method according to claim 8, wherein the at least one profiled surface is a post-curing profiled surface.

13. A method according to claim 12, wherein the at least one profiled surface is provided by milling the fiber cement product.

14. A method according to claim 1, wherein the hydrophobation agent is applied to the at least one profiled surface by spraying.

15. A method according to claim 14, comprising the additional step of changing angular orientation of spray nozzles to ensure an amount of hydrophobation agent is uniformly sprayed over the at least one profiled surface and reaches corners thereof.

16. A method according to claim 1, wherein the silane-based liquid comprises at least 50% w of the at least one silane.

17. A method according to claim 1, wherein said grooves are milled to a depth 0.15 mm to 0.5 mm, and maximum width of 4 mm to 15 mm.

18. A method according to claim 1, wherein the hydrophobation agent is also solvent-free.

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

20. A fiber cement product according to claim 19, wherein the at least one profiled surface is free of silane- and siloxane-residue.

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.

(8) 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.

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

(10) 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].

(11) 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.

(12) 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.

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

(14) 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.

(15) 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.

(16) 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.

(17) TABLE-US-00002 TABLE 2 results White residue Beading; visual Rilem test after 48 h present? assessment (1 test # (ml) (y/n) 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

(18) 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.

(19) 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 α between the bottom 124 and each of the flanks 126 and 128 is 110°, thus providing slopes with a slope width S.

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

(21) 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.

(22) 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.

(23) 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.

(24) 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.

(25) 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.