ASSEMBLY WITH DETACHABLE CONSTRUCTIONAL LAYER

Abstract

A layered assembly including a substrate based on a hydraulically binding composition, a primer layer, and a constructional layer wherein the primer layer is positioned between the substrate and the constructional layer, and wherein the primer layer includes a polymer and a wax. The invention also relates to methods for producing the layered assembly and methods for detaching the constructional layer from the layered assembly.

Claims

1. A layered assembly comprising (a) a substrate based on a hydraulically binding composition, (b) a primer layer, and (c) a constructional layer wherein the primer layer is positioned between the substrate and the constructional layer, and wherein the primer layer comprises a polymer and a wax.

2. The assembly of claim 1, wherein the primer layer comprises from 50 to 85 wt. % of wax and from 15 to 50 wt. % of polymer, based on the total weight of the primer layer.

3. The assembly of claim 1, wherein the T.sub.g of the polymer is between 50 C. and 30 C., preferably between 30 C. and 10 C.

4. The assembly of claim 1, wherein the polymer is based on at least one monomer type selected from the group consisting of vinyl acetate, ethylene, acrylate, acrylonitrile and styrol.

5. The assembly of claim 1, wherein the polymer is ethylene vinyl acetate copolymer or polyacrylate.

6. The assembly of claim 1, wherein the wax is a synthetic wax, natural wax, and/or modified wax.

7. The assembly of claim 1, wherein the primer layer is not cured and/or wherein the primer layer does not comprise a curing catalyst.

8. The assembly of claim 1, which comprises at least one electrically conductive component.

9. The assembly according to claim 8, wherein the electrically conductive component comprises fibers, wires, strips, a mesh, grid or textile fabric and/or particles wherein the electrically conductive component comprises carbon particles and/or carbon fibers.

10. The assembly of claim 1, which comprises at least one electromagnetically inducible component.

11. The assembly according to claim 10, wherein the electromagnetically inducible component comprises fibers, wires, strips, a foil, net, grid, mesh or textile fabric, wherein the electromagnetically inducible component consists of or comprises metal metal oxide, or carbon.

12. The assembly of claim 1, wherein the primer layer comprises at least one additive, selected from the group consisting of emulsifier, dispersant, defoaming agent and thickener.

13. The assembly of claim 1, wherein the substrate is concrete or screed and/or wherein the hydraulically binding composition is based on cement or calcium sulphate.

14. The assembly of claim 1, wherein the constructional layer is a wall cover, floor cover, tile, plate, sheet, laminate, textile, carpet or cementitious layer, and/or wherein the constructional layer comprises a material selected from the group consisting of ceramic, glass, stone, plastic, textile, asphalt, plaster and concrete, and/or wherein the basis weight of the constructional layer is at least 400 g/m.sup.2.

15. The assembly of claim 1, wherein the bonding strength between the constructional layer and the substrate at 25 C. is at least 0.7 N/mm.sup.2.

16. A structural part comprising an assembly of claim 1, wherein the structural part is preferably a wall, floor, ceiling or part thereof.

17. A method for preparing a layered assembly according claim 1, comprising in consecutive order the steps of (A) coating a substrate with a primer composition, which comprises a polymer and a wax, (B) drying the primer composition to obtain the primer layer, and (C) applying the constructional layer onto the primer layer.

18. The method of claim 17, wherein the substrate is coated with the primer composition in an amount of from 5 to 500 ml/m.sup.2 of the primer composition and/or of from 2 to 200 g/m.sup.2 of solid components of the primer composition.

19. A method for detaching the constructional layer from a layered assembly of claim 1, comprising (i) heating the assembly until the primer layer softens or melts, and (ii) removing the constructional layer from the substrate.

20. The method according to claim 19, wherein the primer layer is heated to a temperature of between 60 C. and 120 C.

21. The method according to claim 19, wherein the assembly comprises an electrically conductive component and is heated by applying an electrical current, and/or wherein the assembly comprises an electromagnetically inducible component and is heated by applying an electromagnetic field.

Description

[0111] Exemplified embodiments of the invention and aspects of the invention are shown in the figures.

[0112] FIG. 1 shows schematically and in exemplified form a layered assembly of the present invention and method for detaching the constructional layer by heating the assembly with an external heat source.

[0113] FIG. 2 shows schematically and in exemplified form a layered assembly of the invention comprising a conductive component and method for detaching the constructional layer by applying an electrical current.

[0114] FIG. 3 shows schematically and in exemplified form a layered assembly of the invention with an inducible component, which is an inducible mat, and a method for detaching the constructional layer by applying an electromagnetic field.

[0115] FIGS. 1 to 3 show layered assemblies and methods for detaching the constructional layer from the substrate after heating in exemplified form. Each layered assembly 4 consists of substrate 1, primer layer 2 and constructional layer 3. The substrate can be a concrete slab.

[0116] When heat is provided or generated, the primer layer comprising the polymer and wax is softened or molten and the constructional layer is detached.

[0117] FIG. 1 shows an aspect in which primer layer 2 is heated by external heat source 5, which is moved over the surface of constructional layer 3. In this aspect, the primer layer 2 does not comprise a conductive or inducible component. After softening the primer layer, the constructional layer can be detached.

[0118] FIG. 2 shows a layered assembly 4 in which the primer layer comprises a conductive component in the form of copper wires 6. The copper wires 6 are laid in parallel on the surface of concrete slab 1. The primer layer 2 is coated on concrete slab 1 such that the copper wires 6 are embedded in the primer layer 2 (only half the primer layer is shown for better understanding). Constructional layer 3 is applied on the surface of primer layer 2 and a stable layered assembly 4 is obtained. For purposive detachment of constructional layer 3, a voltage is applied through copper wires 6 by electrodes 7, 8. The inherent electrical resistance of the copper wires 6 has the effect that primer layer 2 is heated. After softening of the primer layer 2, constructional layer 3 can be detached from substrate 1.

[0119] FIG. 3 shows an alternative aspect of a layered assembly with an inducible net 9 embedded in primer layer 2. In this aspect, voltage is applied through coil 10 which causes electromagnetic induction of the inducible net 9. The induction has the effect that the inducible net 9 is heated and primer layer 3 is softened. The coil 10 can be moved over the surface of constructional layer 3 to provide enough heat across the entire area. After softening of primer layer 2, the constructional layer 3 can be detached from substrate 1.

[0120] The layered assembly and methods solve the problem underlying the invention. A comparatively simple and efficient system is provided for stable attachment of constructional layers to cementitious substrates, which can be used for a wide range of construction and building applications. On the other hand, the constructional layer can be purposively detached at a desired time in a simple and convenient manner, for example when the layered assembly is refurbished or renovated, recycled, repaired or changed. The detachment of the constructional layer can be carried out precisely and requires only low amounts of energy. If the system is adjusted appropriately, the constructional layer can be removed by hand, and thus without exerting strong mechanical force or using special devices. The system and method according to the invention are user-friendly, and any undesirable generation of dust, debris, noise, heat, damage and/or working hazards can be avoided.

EXAMPLES

[0121] Layered assemblies were produced with various primer layers. The mechanical stability at room temperature and release upon heating were evaluated as outlined in the following.

Production of Primer Compositions

[0122] Primer compositions were prepared from polymer and wax dispersions or emulsions as summarized below. The defoaming agent used was SAG 240 (Momentive silicon oil emulsion defoamer, density 1.0039 g/cm.sup.3). To the wax emulsion, the polymer emulsion or dispersion, defoaming agent and water were added. The components were mixed in a dissolver at a rotational speed of 500 to 1,000 UpM.

TABLE-US-00001 Type Trade mark, supplier P1 acrylic emulsion polymer solids Ucar Latex DL 435, content 49%; T.sub.g 0 C. DOW Chemical P2 acrylic ester copolymer dispersion Acronal A 380, BASF solids content 62%; T.sub.g 22 C. AG P3 acrylic emulsion polymer solids Primal CA 172, content 60.5%-61.5%; T.sub.g 21 C. DOW Chemical W1 paraffin combination wax dispersion LUBA-print 280W, solids content 50%; drop point 82 C. Mnzing W2 ester wax dispersion solids LUBA-print KL 30, content 30%; melting point 72-80 C. Mnzing

Production of Layered Assemblies

[0123] Layered assemblies were produced from the substrate, primer compositions as outlined above, and a cementitious constructional layer. The substrate was a concrete slab (paving slab) with the dimensions 29.7404.5 cm, which is commercially available from Mosaicos Solana. Each cleaned and dried substrate slab was coated with 5 to 6 g (corresponding to 42 to 50 g/m.sup.2) of the primer composition. The substrate with the coated primer composition was left standing until the primer layer became solid and completely dry. A 5 mm margin was adhered around each primer layer-coated substrate slab with PTW Fixband (510 mm). The constructional layer was a floor cover prepared from a cementitious composition of trademark Thomsit DX (PCI Augsburg GmbH). The cementitious composition was initially suspended with 260 g water per kg solid. The cementitious composition was poured onto the surface of the primer layer in an amount of 900 to 1000 g per slab and left standing until hardening and setting was completed.

Properties of Layered Assemblies

[0124] The layered assemblies prepared as outlined above were tested for stability at 22 C. and release of the constructional layer upon heating. The heating temperature at which the layered assemblies were dismantled was set to 65 C.

[0125] The stability of each layered assembly was determined in a rating test at room temperature and when the primer layer was heated. Grades from 1 (very good) to 6 (deficient) were defined for adhesion at 22 C. and release upon heating as outlined in the following:

TABLE-US-00002 Grade Adhesion at 22 C. Release upon heating 1 can only be removed by using tools (A); falls off by itself or can be very good adhesion comparable to conventional removed by hand (nearly no polymer-based primers or better adhesion) 2 can be removed by using tools (B); can easily be removed by using a good adhesion still comparable to conventional painter's spatula or more polymer-based primers difficultly by hand 3 can be removed by using tools (C); can be removed with low to satisfactory adhesion significantly lower than with medium force by using a conventional polymer-based primers painter's spatula 4 can be removed with low to medium force can be removed by using tools sufficient by using a painter's spatula (C) 5 can easily be removed by using a painter's can be removed by using tools poor spatula or more difficult by hand (B) 6 falls off by itself or can be removed by hand can only be removed by using deficient (nearly no adhesion) tools (A)
Level of Strength Needed when Using Tools:

[0126] (A)=heavy force when using hammer and chisel

[0127] (B)=medium force when using hammer and chisel

[0128] (C)=low force when using hammer and chisel

[0129] The results are summarized in Table 1. The results show that the layered assembly of the invention is highly stable at room temperature. On the other hand, the bonding strength can be reduced at elevated temperature and the constructional layer can be purposively detached in a convenient manner at elevated temperature. The assembly can be optimized for a specific substrate and constructional layer by varying the wax to polymer ratio and types.

TABLE-US-00003 TABLE 1 Primer compositions and results 1 2 3 4 5 Primer composition polymer type P1 P2 P3 P3 P1 wax type W1 W2 W3 W3 W2 polymer [% vol] 23.33 17.33 17.33 23.33 10.00 wax [% vol] 46.62 52.62 52.62 46.62 59.95 Defoamer [% vol] 0.05 0.05 0.05 0.05 0.05 Water [% vol] 30 30 30 30 30 polymer [% wt.] solids 32.8 40.4 27.7 37.9 21.4 wax [% wt.] solids 67.2 59.6 71.3 62.1 78.2 Results primer layer level adhesion at 22 C. 2 2-3 3 2 4 level release after heating 3-4 3 3 5 1-2

[0130] The results demonstrate that the layered assembly provides advantageous properties for layered assemblies based on cementitious substrates in building applications, which are on the one hand highly stable, but on the other hand can be dismantled conveniently if desired.