FR2921570A1 - Varnishing or painting comprises depositing mineral sublayer composed of mineral primer on the support, optionally drying, incorporating a hardener of the mineral sublayer, depositing the preparation on the support, and resting - Google Patents

Abstract

Process for varnishing or painting comprises: depositing mineral sublayer composed of mineral primer on the support; optionally drying according to the first drying time; incorporating a hardener of the mineral sublayer; depositing the preparation on the support; and resting according to a second rest period, where the hardener is present in varnish or paint, which penetrates in the mineral primer and provokes its grip while the varnish or paint carries out drying.

Description

The present invention relates to a varnishing or painting process using an undercoat mineral primer. The method is applicable to any water-permeable substrate such as wood and its derivatives, paper and its derivatives, building walls and in general any support having a certain porosity and intended to be painted or varnished. Deposition of varnish or paint on a surface to protect it from bad weather or wear has been known since antiquity. However, these varnishes or paint always have a limited effect over time, especially under the effect of moisture. Various methods are known for improving the resistance of a paint or paint to wear or impact. FR 2861738 discloses, for example, a wood surface coating composition, in particular aqueous varnish, which has improved properties of resistance to abrasion, impact and household products. In this composition, a mineral filler is added to the varnish and binds to the polymer network via a suitable coupling agent or hardener of the composition. The composition may or may not require the use of a hardener, but it is always single-layered. It is the object of the invention to provide a method that considerably improves the properties of a lacquer or paint deposit by using a two-component cement, consisting of a sub-component. -layer of mineral primer and a hardener.

For this purpose, the invention provides a process comprising the steps of: a) depositing a mineral undercoat on the support to be painted or varnished, b) allowing to dry, optionally, according to a first drying time, c) incorporating a hardener of said mineral undercoat to the varnish or the paint, d) deposit this preparation on the support to be painted or varnished, e) leave to rest after a second rest period, so that the hardener present in the varnish or paint penetrates into the mineral primer and causes its setting while the varnish or paint performs its drying process.

The invention relates in particular to the use of a two-component cement, consisting of a mineral powder mixture constituting a mineral undercoat, dry or dissolved in a solvent, as well as a hardener of said mineral mixture, for the deposit of a varnish or paint. The slow setting of this mineral primer makes it possible to obtain a mineral crosslinking between the support, the primer undercoat and the varnish or the paint. This mineral cross-linking has the following effects: strengthening of the bonds between the support and the varnish and consequently a better resistance to wear; the mineralized sub-layer is harder; • better resistance of paints and varnishes to humidity; the mineral crosslinking being scalable in a humid environment, the presence of moisture in the support and on the paint causes the progressive and progressive taking of the mineral sub-layer and this, throughout the aging of the painted surface. The adhesion of the varnish on the support is reinforced by this mineral cross-linking, which develops in a humid environment; • an improvement of the mechanical and chemical properties of the support system / undercoat / paint or varnish such as the hardening of the surface of the support, a better resistance to fire: the mineral sublayer which does not burn isolates the support of the paint this which slows down the setting of the fire in the middle of the support; • less harmful paints and varnishes: the use of less volatile solvents may be preferred instead of the highly volatile and often harmful organic solvents that are currently used for common paints and varnishes, the drying of varnish or paint being facilitated by the circulation of the mineral-loaded moisture of the hardener through the layer of varnish or paint and by the mineral setting of the underlayer; • better acoustic properties of the mineralized support; an acoustic installation will reflect more high frequencies and also generate more harmonics if it is varnished or painted according to the invention.

The process is applicable to any type of varnish or paint. When the solvents of the paint or varnish and the hardener are of different natures, for example an organic solvent and water, the mixture must be vigorously stirred to obtain a fine emulsion. The two-component cements can be homemade, produced in the laboratory, such as, for example, Cordi-Geopolymer's DavyaTM cement, or in industry. They consist of a mineral powder mixture, used dry or diluted in a volatile solvent, for example water, and a liquid or solid curing component of said mineral mixture. By mineral mixture is meant a mixture derived from geological materials containing in variable quantity, for example limestone and its derivatives, aluminas, silicas and / or silico-aluminates; other organic minerals or resins to correct the color, texture and flowability of this mixture can be added to this preparation. The hardener allows the setting of the mineral mixture; it may be based on silicates, for example potassium silicate, sodium silicate or a cement extract called cement water; in the case of a commercial two-component cement, the hardener provided for this purpose is used. The hardener may be in liquid or solid form, that is to say in the form of silicates in solution and / or in the form of particles suspended in a liquid, either in the form of powder composed of crystalline silicate and / or other ground mineral particles, used as is. The essential characteristic of this hardener being, that associated with the minerals deposited in underlayer, it provokes the mineral setting of the cement.

An interesting characteristic of these two-component cements is that the bringing together of these two components, most often carried out in the presence of water, provokes the setting of the mineral mixture in the form of cement even in the absence of air (cement anaerobic setting). However, it is also possible to use a single-component cement containing silicates as a mineral undercoat, pure or associated with minerals that promote the anaerobic cement, such as pozzolan or clay; in this case, the addition of water, mineral salts, or an extract of cement varnish then takes the role of hardener.

According to one embodiment of the method, use is made of the Cordi-Geopolymer two-component DavyaTM cement, in which the mineral mixture consists of silica and alumina-based geological materials and the silicate hardener is highly concentrated in an alkaline medium.

According to another embodiment, said mineral mixture in powder form consists of a mixture of Portland cement or quicklime, kaolinitic clay and pozzolan. Cement, silico-aluminates or lime are at the base of the mineral catch, clays and pozzolan allow a setting in absence of air. Additives such as organic resins, blast furnace residues or crushed bricks can be used to refine this mineral preparation, for example to adapt its grip to a varnish or a given support, improve the evolutionary grip of the cement.

In this embodiment, the hardener may consist of, for example, cement water, i.e. the supernatant of a mixture of water and cement having boiled for a certain time.

Said cement water is obtained by boiling: between 10 g and 100 g of Portland-type cement, in a volume of water of between 0.5 and 1 liter of water, for a time of between 10 minutes and 1 h, and recovering the liquid part and the suspended dust which appear on the surface during the heating.

Advantageously, 1 <water of cement will be made by boiling 100 g of Portland cement in 1 liter of water for 10 minutes and recovering the liquid part and the suspended dust which are on the surface of this liquid. boiling. It is important that there is enough water in the mixture to be able to recover a sufficient amount of active product, namely the finest particles in suspension and mineral salts during precipitation, supernatant during heating. This particular hardener must be immediately incorporated in the varnish, without being put to dry.

The inorganic mixture deposited in the undercoat is preferably diluted in water to obtain a liquid paste but it can also be used dry or diluted in another volatile liquid such as alcohol or even fat such as oil. , chosen so that it does not interfere with the mineral setting of the cement. The dilution or suspension of this primer depends on the density of the support and its attachment characteristics. Two essential elements must be taken into account in this application: • If the solvent is water, the drying time of this mineral sub-layer must be less than the time required for setting the cement. • The applied mineral primer must be sufficiently thin and / or diluted to obtain a deep penetration of the primer, but it must remain dense.

By way of example, for a moderately sanded softwood support, the dilution should be 20 g of powder per 20 cc of water.

In a first step, this paste is deposited on the support so as to penetrate the mineral mixture as much as possible into the support by means of circular movements of the brush. This mineral primer can also be applied directly in the form of a powder by sanding with a so-called pore-in-mouth cloth, or by adding a collagen or organic resins, which must be very soluble with water or with the solvent of the varnish with the said mineral primer.

In a second step the mineral primer which has just been deposited on the support is allowed to dry. The drying time is variable depending on the temperature and humidity conditions. As indicated above, it must be less than the setting time of the mineral primer if the solvent is water; in general, this primer will be dry to the touch in 15 minutes and ready to varnish after 3 hours. This step is of course irrelevant if the mineral primer has been deposited as a powder.

In a third step, the hardener is incorporated in the varnish or paint to be deposited on the support. In the case where the solvent of the varnish or paint is water-based, said incorporation is generally without difficulty. In the case where said solvent is organic, for example a varnish or a glycerophthalic paint, vigorously stir the mixture to achieve a fine emulsion and achieve this incorporation. The hardener may also be incorporated into the lacquer or paint in powder form. The dosage of the hardener is, for example, established as a function of the amount of mineral deposited as an underlayer on the support, according to the instructions for use of the two-component cement if a commercial two-component cement is used, according to take tests of two-component cement without varnish, or empirically. If the underlay is a cement containing silicates, pure water is the hardener.

In a fourth step, the varnish or the paint loaded with hardener is conventionally applied to the support previously covered with said mineral sub-layer. Possibly a rough wiping of the support is carried out in order to remove the excess undercoat powder.

The fifth and last step of the process consists of a slow drying of the varnish or paint so that the setting or mineral crosslinking between the support, the undercoat and the varnish or the paint develops. The varnish or paint then dries in two phases: • Drying by evaporation of the solvent: the drying characteristics of the varnish are unchanged (it becomes dry to the touch) but it is breathable because the hardener captures moisture; the osmotic pressure of the mineral primer allows the passage of moisture through the varnish. • Taking mineral components: said moisture causes a gradual setting or mineral crosslinking inside the varnish, in the mineral sub-layer and on the surface of the support, due to the setting of the cement. The speed of this internal grip depends on the porosity of the varnish or paint and the degree of ambient humidity. In general, the more the varnish is in a humid environment, the more this is important. It is recommended, during the drying time by evaporation of the varnish, to maintain the wet varnish so as to initialize this mineral setting, either by incorporating water into the varnish or by keeping the varnish in a humid environment during the drying time. some nail polish.

The initialization and the development of a mineral cross-linking between the support, the undercoat and the varnish or the paint can occur naturally, but one can also favor it by creating the conditions so that it is triggered. If it is desired to accelerate and strengthen the mineral setting of the varnish, the varnish can be maintained in the presence of water longer, for example the setting time of the cement used, either by maintaining the support in a humid environment, or by incorporating more varnish water used. The importance of this presence of water depends on: • the type of two-component cement used, lime-based cements being more subject to this addition of water than silicoaluminate-based cements, • permeability to the water of the varnish or the paint: if the varnish is sufficiently permeable, the osmotic pressure of the mineral components can cause a natural presence of water in the varnish 20 during the setting of the two-component cement.

One method for maintaining the wet substrate and promoting the mineral setting of the two-component cement incorporated in the varnish consists, for example, in covering the support with a plastic film.

Claims (12)

claims 1. Varnishing or painting process, characterized in that it comprises the following steps: a) depositing a mineral sub-layer composed of a mineral primer on the support to be painted or varnished, b) allow to dry, optionally, according to a first drying time, c) incorporating a hardener of said mineral sub-layer into the lacquer or paint, d) depositing said preparation on the support to be painted or varnished, e) allowing to rest at a second resting time, so that the hardener present in the varnish or the paint penetrates into the mineral primer and causes its setting while the varnish or paint performs its drying process. 2. Varnishing process or paint according to claim 1, characterized in that said mineral sub-layer consists of a mixture of cement or quicklime, kaolinitic clay and pozzolan. 3. A method of coating or painting according to claim 1, characterized in that said mineral sub-layer consists of a mixture of geological materials based on silica and alumina. 25 4. Varnishing or painting process according to one of the preceding claims, characterized in that prior to the first step, said mineral primer is diluted or suspended in a liquid and in that, during the first step, said mineral sub-layer is deposited on the support in liquid or pasty form. 920- 10- 5. varnishing process or painting according to claim 4, characterized in that said liquid is water, an alcohol or an oil. 6. varnishing process or painting according to one of claims 1 to 3, characterized in that, during the first step, said mineral sub-layer is deposited on the support in powder form. 7. varnishing process or painting according to one of the preceding claims, characterized in that said hardener of the mineral sub-layer is incorporated in the varnish or paint in liquid form. 8. varnishing process or paint according to claim 7, characterized in that said liquid hardener is a cement water. 9. A varnishing or painting process according to one of claims 1 to 6, characterized in that said hardener of the mineral sub-layer is incorporated in the varnish or paint in solid form. 10. A method of varnishing or painting according to one of the preceding claims, characterized in that the active ingredient of said hardener consists of at least one silicate. 11. Varnishing or painting process according to one of claims 1 to 7, characterized in that the mineral sub-layer is a cement which contains silicates and the hardener is water. 12. varnishing process or painting according to one of the preceding claims, characterized in that during said second rest period the support is kept moist so as to promote the initialization and development of a mineral cross-linking between the support, underlay and varnish or paint.