EP0426575B1 - Product for the preparation of a rendering and insulating exterior plastering made thereof - Google Patents

Description

The subject of the invention is a product for the preparation of a cement coating intended to cover the external face of a support such as a building wall and which can be used, in particular for the production of an insulation coating. from the outside.

For some time now, the thermal insulation of buildings from the outside has developed, and the technique which consists of covering the outside face of the wall to be insulated with a set comprising, from the inside, is very commonly used. towards the outside, an insulating wall on which is applied a reinforced base layer itself covered with a finishing coating.

The insulating wall usually consists of expanded polystyrene (PS E) or glass wool or rock wool panels and can be fixed to the support either by gluing, or by various devices of the staple type or pulling in plastic or metallic material.

The base layer consists of a coating in which a mesh-shaped reinforcement, generally made of fiberglass, is coated. As a result, the coating is applied in at least two passes, respectively a first pass for producing a relatively thin bonding layer spread over the external face of the insulating wall and on which the trellis is laid, the latter being then covered with a second thicker layer constituting the body of the coating.

The assembly is covered with a finishing coating itself consisting of at least one primary layer for the protection of the base layer and which is covered, most often, by a decorative layer.

So far, it seemed normal to make the different plaster layers using different products specially adapted to their function.

When the insulation is stuck on the wall, we therefore use, first of all, an adhesive generally consisting of a paste composed of mineral fillers and additives associated with a resin and which is mixed with a certain proportion of cement.

The base layer, also called undercoat, is intended for the coating and bonding of the reinforcement on the insulation. As this layer is applied to the insulation and exposed to the sun and cold, it must have a certain flexibility to resist differential expansions and that is why we generally incorporate a certain amount of resin into the coating. same product as for glue, by varying the cement dosages.

In both cases, the paste contains a fine-grained mineral filler.

Often it is preferred to cover the base coat with a primer before applying the topcoat. The latter is generally in the form of a thick, grainy paste consisting of a mixture of mineral fillers and, optionally, colored pigments, in an organic binder.

The differential expansion is absorbed thanks to the flexibility of the reinforced base layer.

The three coatings are of different compositions, which can cause different tensions and a risk of cracking and delamination.

On the other hand, the bonding adhesive and the various coatings must be prepared separately at the time of their application and, before applying a layer, it is necessary to wait for the drying of the previous layer, which requires a time. quite long, varying according to atmospheric conditions, and which can go up to 48 hours.

When making large buildings, the drying of a layer can take place on one part of the building during the installation on another part. On the other hand, for smaller supports, for example for a detached house, the need to wait for one layer to dry before applying the next can cause significant loss of time.

To avoid this drawback, it has already been proposed to use the same mortar to make the base layer and the finishing coating, the whole forming a single practically homogeneous layer, capable of being applied to the insulating panel and, in at the same time, to resist the effects of humidity and temperature variations (DE-A- 2 703 342 corresponds to the preambles of claims 1 and 7).

Such a mortar contains a filler, a hydraulic binder, cellulose and a synthetic material, in particular a resin, resistant to alkaline products to obtain a water barrier effect. It is preferable to use a resin with a highly branched chain and therefore having a relatively glass transition temperature. high. Furthermore, the load must include a fairly large proportion of medium sand with a particle size of up to 5 mm and such a mortar therefore intended for the preparation of a fairly thick coating.

In addition, this mortar is prepared, as usual, by mixing dry products, then adding water for mixing. However, it is rare that one prepares exactly the quantity corresponding to that which one needs and, after the application of the coating, there remains a certain quantity of mortar which cannot be preserved. This results in significant losses.

The subject of the invention is a new product for producing an insulating coating which does not have such drawbacks, and which, while retaining the advantages of known products, makes it possible to prepare a coating with high cohesive power and having, even in low thickness, very good qualities of resistance, impermeability, flexibility, adhesion to the support and external appearance.

The invention therefore relates to a thermal insulation coating intended to cover the outside face of a support and comprising, in cross section, from the inside to the outside, a wall of insulating material fixed on the outside face of the support and a coating plaster in which a lattice-like reinforcement is coated, said plaster consisting of a cement mortar containing, as main constituents, a filler consisting of a mixture of fine sand and medium sand, a hydraulic binder and a resin, said constituents being kept separately and mixed in desired proportions at the time of application

According to the invention, the coating is produced from two components stored separately, respectively, a first component comprising, in desired proportions the filler, the hydraulic binder and additives and a second component comprising the resin and additives, said resin being in aqueous dispersion and having a glass transition temperature close to 0 ° C, and the second component is mixed with the first component at the time of application in a proportion of at least 30% of the amount of cement contained in the first component.

In the case where the insulating wall is fixed to the external face of the support by means of an adhesive, this is produced, according to the invention in the same way as the base coating and the finishing coating, with from the same two components which are mixed during bonding.

The choice and dosage of the various constituents, and in particular sand and resin, therefore makes it possible to use the same product both as an adhesive, as a base coat and as a finishing coating.

Advantageously, an aqueous dispersion of vinyl copolymer is chosen in which the particle size is between 0.2 and 3 microns, and more preferably between 0.5 and 2 microns. Under these conditions, the setting time is relatively short. Also, the homogeneity of the coating is improved and, consequently, its cohesive power is higher.

As vinyl copolymers, copolymers of vinyl ester and of weakly branched ethylenic monomers are preferably used, and more preferably copolymers of vinyl acetate and ethylene.

A very important advantage of the invention lies in the fact that thin coatings are produced, generally between 3 and 7 mm, which have qualities superior to those of thick coatings without their drawbacks. In addition, the coating according to the invention makes it possible to produce coatings having a traditional surface condition.

It will be noted that a minimum thickness of 3 mm of the coating according to the invention is sufficient to ensure the durability of the waterproofing. In fact, during water absorption tests, it has been observed that the coating according to the invention has a capillary absorption significantly lower than that of a traditional coating coating.

Thanks to its flexibility and its homogeneity, the coating produced with the coating according to the invention exhibits good behavior when subjected to accelerated aging tests. In fact, no blistering, discoloration, cracking, water passage, detachment and significant chalking of the surface type were observed.

However, the invention also relates to the product as defined by claim 7 developed for the preparation of this coating and consisting of two components kept separately, for example:
A first component consisting of a cement mortar having the following composition by weight:
15 to 30% white or gray cement,
40 to 50% of fine sand with a particle size of up to about 0.5 mm, and preferably between 0.08 and 0.4 mm,
25 to 45% and preferably 25 to 35% of an average sand with a particle size between 0.5 and 1.5 mm approximately,
and further containing a rheology agent, a water repellency agent and a thixotropy agent,
and a second component consisting of a vinyl copolymer in aqueous dispersion whose glass transition temperature is between 0 and 5 ° C., added with an anti-foaming agent and a preservative, the active proportion, by weight, of the second component being from 30 to 35% of the amount of cement contained in the first component, these two components being kept separately, the resin being mixed with the mortar, in desired proportion, only at the time of use for the preparation coating.

According to another advantageous characteristic, the resin in aqueous dispersion provides sufficient water for the dilution, no addition of water being normally required.

However, the invention will be better understood from the detailed description of a particular embodiment.

In the single figure, there is shown such a coating in cross section and on an enlarged scale.

Conventionally, the insulating coating which is applied to the outer face 10 of a support 1 such as a building wall, comprises an insulating wall 2 consisting, for example, of polystyrene panels placed side by side, of a base layer 3 in which is incorporated a reinforcement 4 and a finishing coating 5 produced in at least one layer.

The panels constituting the insulating wall 2 are fixed to the support 1 either by means of staples or dowels, or by gluing. In that case, as shown in the drawing, there are on the outer face 10 of the wall 1, strips of adhesive paste 6 spaced from one another and to which the insulating panels 2 are applied by crushing the paste 6.

The panels 2 are then covered with a first layer of plaster 31 on which the mesh 4 is applied, then the latter is covered with a second layer 32 so as to be completely coated, the second layer 32 is then covered with the same product, projected by a compressed air device, for example.

The mesh 4 is made, as usual, of fiberglass or kevlar with square meshes of 3 to 5 mm. As indicated above, to make the paste 6 and the base layer 3, the same coating consisting of two components mixed at the time of application, respectively a cement mortar and a resin.

The first component is a mortar preferably having the following composition:
15 to 30% and preferably 16 to 25% cement
white or gray,
40 to 50% of fine sand with a particle size of up to about 0.5 mm and preferably between 80 and 400 microns,
25 to 45% and, preferably, 25 to 35% of an average sand with a particle size ranging from 0.5 to 1.5 mm,
up to 0.3% and preferably between 0.08 and 0.25% of a rheology agent such as a cellulose derivative,
up to 0.2% and preferably between 0.05 and 0.15% of a water repellant
and a thixotropy agent, for example short fibers, in a proportion such that the weight ratio of this thixotropy agent to the active fraction of the second component is at most equal to 10% by weight.

The second component is a dilute resin with a low glass transition temperature combined with an anti-foaming agent and a preservative.

Preferably, a vinyl copolymer is used, the glass transition temperature of which is between 0 ° C. and 5 ° C.

The two components are kept separately and mixed only at the time of application in proportions of 20 to 35% of resin relative to the amount of cement contained in the mortar, a proportion of 32% being particularly advantageous.

The amount of water contained in the second component is normally sufficient to adequately hydrate the hydraulic binder.

Given the grain size and the dosage of the medium sand contained in the mortar, the presence of grains up to 1.5 mm secures the coating and the operation of the mesh inside the plaster and the presence a significant proportion, at least equal to 40%, of fine elements associated with a resin and with additives makes it possible to ensure the adhesion of the coating 3 to the insulating panels and to the mesh 4.

Furthermore, the presence of a significant proportion of medium sand gives the coating a sufficient compressive strength to quickly apply another layer. We can thus give to the base layer 3, a relatively small thickness but, however sufficient to ensure the durability of the waterproofing, for example of the order of 3 mm.

Furthermore, thanks to the mixing, in the mortar, of fine sand and medium sand and the addition of a resin, the same coating can be used to make the finishing coating 5, the proportions of fine elements and resin providing the plaster with the necessary flexibility while the proportion of medium sand gives it a traditional-looking surface finish. The thermoplastic nature of the coating is less marked than that of the plastic coatings usually used and is less likely to fix ambient dust.

In addition, the use, as resin, of a vinyl copolymer having a low glass transition temperature (between 0 and 5 ° C) and in particularly high proportions compared to the hydraulic binder (30 to 35% of the amount cement) allows, when this resin is combined with the solid component, to prepare a perfectly homogeneous paste which gives a coating with very high cohesive power.

It has also been found that, despite the presence of a fairly large proportion of medium sand, the coating according to the invention could however be used as an adhesive product for bonding the insulation to the support.

Thus, thanks to the use of the product which has just been defined, the same components can be used to produce a single coating having all the qualities required to constitute the adhesive product 6, the base layer 3 and the finishing layer 5 .

It can therefore be seen that, thanks to the invention, the layers 3 and 5 are in fact made up of the same product and that it is not necessary to wait for the complete drying of the base layer before apply the finish coating. On the contrary, it is even advantageous not to wait too long to apply the finishing layer 5 so as to improve its adhesion. In practice, as for the production of conventional coatings over a certain thickness, we will simply wait, for a new pass, for the previous layer to be sufficiently hardened to support the application of the next. The presence of medium sand in the coating promotes resistance to compression.

It can therefore be seen that the two layers 3 and 5 will simply be produced continuously in several passes, in the same way as a conventional coating.

Compared to the systems used until now and which required the complete drying of a plaster layer before the installation of the next layer, we can thus obtain a gain of 50% of the plaster installation time for a house individual. In large buildings where it is possible to coat one part of the building while another part is being dried, the time saving is less but can however be estimated at 20%, approximately to the extent that staff hardly need to travel.

Moreover, another saving in time and materials, results from the fact that the product according to the invention makes it possible to produce thin coatings, generally between 3 and 7 mm and which however have excellent qualities of resistance, waterproofness, flexibility, adhesion to the support and external appearance.

But another very important advantage of the invention also resides in the fact that only two components must be available on the site which are kept separately so as to be mixed only at the time of mixing. In this way, it is possible to assess, as required, the amount of product to be prepared and thus minimizes the loss of product at the end of the operation.

On the other hand, if the invention has been developed especially for the production of insulation coatings from the outside, it is not limited to this single application.

Indeed, thanks to its qualities of resistance, external appearance, adhesion to the support and relative flexibility, the coating prepared from the two components defined above can advantageously be used as a simple finishing coating applied directly to the outside face of a wall.

Claims (12)

1. A coating for thermal insulation intended to cover the outside face of a support (1) and comprising, in cross-section, from the inside to the outside, a facing (2) made of insulating material fixed to the outside face of the support (1) and a coating coat (3, 5) in which lattice-form strengthening (4) is embedded, said coat (3, 5) consisting of a cement mortar containing, as main constituents, a filler consisting of a mixture of fine sand and medium sand, a hydraulic binder and a resin, said constituents being stored separately and mixed in the desired proportions at the time of application, characterized by the fact that the coat is produced from two separately stored components, respectively a first component consisting of, and in the desired proportions, the filler, the hydraulic binder and additives, and a second component consisting of the resin and additives, that the resin is in aqueous dispersion and has a vitreous transition temperature of close to 0°C, and that the second component is mixed with the first component at the time of application inaproportion of at least 30% of the amount of cement contained in the first component.
2. Insulating coating as claimed in claim 1, in which the insulating face (2) is fixed on the outside face of the support (1) by means of a glue, wherein the fixing glue (6) for the insulating face (2) is produced in the same way as the base coat and the finish coat, from the same two components which are mixed at the time of glueing.
3. Insulating coating as claimed in either of claims 1 and 2, wherein the active proportion of the second component is from 30 to 35% of the amount of cement contained in the first component.
4. Insulating coating as claimed in one of claims 1, 2 and 3, wherein the first component is a mortar containing, by weight:
      15 to 30% of white or grey cement,
      40 to 50% of a fine sand having a particle size of up to approximately 0.5 mm, and
      25 to 40% of a medium sand having a particle size of between approximately 0.5 and 1.5 mm,
   the said mortar also containing a rheological agent, a waterproofing agent and a thixotropic agent.
5. Insulating coating as claimed in one of the preceding claims, wherein the second component is a vinyl copolymer which has a vitreous transition temperature of between 0°C and 5°C and to which an anti-foam agent and conservative agent have been added.
6. The insulating coating as claimed in claim 3, wherein the first component has the following composition by weight:
      16 to 25% of white or grey cement,
      40 to 49% of a fine sand having a particle size ranging from 0 to 400 microns and preferably from 80 to 400 microns,
      25 to 35% of a medium sand having a particle size ranging from 0.5 to 1.5 mm,
      0.08 to 0.25% of arheological agent, preferably a cellulose derivative,
      0.05 to 0.15% of a waterproofing agent,
      and a thixotropic agent.
7. Product for the preparation of a cement coat, which comprises separately stored components, characterized by the fact that, respectively, a first component consists of a cement mortar comprising 40 to 50% of a fine sand and 25 to 45% of a medium sand, and a second component consists of a dilute resin to which an anti-foam agent and conservative agent have been added, the two components being mixed in desired proportions only at the time of use for the preparation of the coat.
8. Product for the preparation of a coat as claimed in claim 7, wherein the active proportion of the second component is from 30 to 35% of the amount of cement contained in the first component.
9. Product for the preparation of a coat as claimed in either of claims 7 and 8, wherein the first component is a mortar containing, by weight:
      15 to 30% of white or grey cement,
      40 to 50% of a fine sand having a particle size of up to approximately 0.5 mm, and
      25 to 40% of a medium sand having a particle size of between approximately 0.5 and 1.5 mm,
   the said mortar also containing a rheological agent, a waterproofing agent and a thixotropic agent.
10. Product for the preparation of a coat as claimed in one of claims 7 to 9, wherein the second component is a vinyl copolymer having a vitreous transition temperature of between 0°C and 5°C and to which an anti-foam agent and conservative agent have been added.
11. Product for the preparation of a coat as claimed in one of claims 7 to 10, wherein the first component has the following composition by weight:
       16 to 25% of white or grey cement,
       40 to 49% of a fine sand having a particle size ranging from 0 to 400 microns and preferably from 80 to 400 microns,
       25 to 35% of a medium sand having a particle size ranging from 0.5 to 1.5 mm,
       0.08 to 0.25% of a rheological agent, preferably a cellulose derivative, and
       0.05 to 0.15% of a waterproofing agent.
12. Product for the preparation of a coat as claimed in one of claims 7 to 11, wherein the first component contains a thixotropic agent, such as short fibers, in a proportion such that the ratio by weight of said agent to the active fraction of the second component is at most equal to 10% by weight.

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