FR2861722A1 - METHOD FOR SURFACE TREATMENT OF A SUPPORT COMPRISING ASBESTOS AND ENTERING THE CONSTITUTION OF A BUILDING, SUPPORT THUS OBTAINED - Google Patents

Abstract

The invention relates to a surface treatment method of support, for example fiber cement roofing containing asbestos and used in the construction of buildings. More specifically, the intended surface treatment is intended to render the asbestos building elements of old buildings harmless, by preventing the uncontrolled dispersion of asbestos dust into the atmosphere. The simple, economic method proposed by the invention consists essentially of applying to the support at least one layer of a curable extendible silicone composition and comprising at least one aqueous dispersion of silicone oil; and then allowing said layer or layers to cure by drying and curing / crosslinking so as to form a waterproof silicone elastomeric coating adhering to the support and preventing the spread of asbestos out of the support.The silicone composition is applicable by brushing or by spraying.The crosslinking of the silicone oils intervening in situ on the support is a crosslinking by condensation.The invention is also aimed at the supported support coated with a crosslinked silicone coating obtained in particular by the above method.

Description

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METHOD FOR SURFACE TREATMENT OF A SUPPORT CONTAINING
ASBESTOS AND ENTERING THE CONSTITUTION OF A BUILDING, SUPPORT
SO OBTAINED
The field of the invention is that of the methods of combating the harmful effects of asbestos present in the various building components, for example: roofs, floors, walls or ceilings.

More specifically, the invention relates to the support surface treatment constituting these building elements or building materials used in the building.

 The present invention also relates to surface-treated substrates according to the aforementioned methods.

 Asbestos is a fibrous natural material that for a very long time has been used in building elements or building materials. Thus, we still find in many civil engineering works, plates or tiles asbestos cement (marketed for example under the brands Eternit, Abestolux, Canalit) it is also known for a long time that the dust of Asbestos is a particularly dangerous material for health because its inhalation causes serious diseases of the lungs such as Abestosis and lung cancer.

 While fortunately these asbestos-based building elements or materials are no longer used in the building, many buildings still contain asbestos-laden elements or materials. These are all sources of deleterious asbestos dust release. This is further aggravated by the fact that these old materials are in the process of advanced degradation.

 To counter this, health authorities in many countries have implemented asbestos abatement campaigns and / or neutralization of asbestos pollutants. For example, renovations or the cleaning of asbestos building components, such as asbestos fiber cement roofing slabs, must be carried out under very strict safety conditions for the protection of the operators carrying out these operations. even people close to the treatment site. In particular, the workers must be equipped with protective coveralls and masks to avoid contact and inhalation of asbestos dust inevitably dispersed in the atmosphere during these operations. The constraints and risks to the health of

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 There are therefore a large number of workers involved, which naturally entails very high costs for this type of renovation and / or structural cleaning of old buildings containing asbestos.

By way of example of such operations, mention may be made of high-pressure cleaning with the aid of two suction carriages to prevent pollutant emission of asbestos, this cleaning being followed by application of a primary layer, the latter being covered with a protective coating consisting of a paint for example based on polymer latex. This type of coating does not make it possible to dispense with binding cleaning and furthermore does not include a curing step by curing or crosslinking the applied coating, so that the latter is not likely to prevent a possible propagation of asbestos dust in the ambient atmosphere.

 The flexible waterproof coating marketed under the name Aquafin-2K / M is also known. This coating is obtained from an acrylic emulsion loaded with cement. Such a two-component cross-linking composition after application in two layers and drying in the open air. Such an Aquafin-2K / M coating appears to be relatively friable, which does not allow it to compensate for the cracks and unevenness of relief often present in used building materials. Such a known coating also suffers from a lack of adhesion to asbestos building materials. Last but not least, its friability and least elastic qualities do not allow it to be an effective barrier to the spread of asbestos dust in the atmosphere.

 This weakness in terms of mechanical characteristics (elasticity) is also found in the known system and marketed under the name TRIXSEL. It is a roof sealing system based on the implementation of a cold-applied polyester liquid resin on the support in the form of one or more layers in which there is included a manufactured textile intended to form the reinforcement of the coating. The latter is presented as elastic but its elasticity is quite inadequate. This coating is obtained after curing by polymerization. It therefore appears that this known TRIXSEL system is little or not suitable for surface treatment of asbestos building elements.

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 The paint marketed under the name type waterproof DIP ETANCH100E final is an aqueous acrylic resin resin emulsion, intended to be applied on any new or old current carrier to form a semi-thick waterproof coating hardenable after drying. Here again, the weak mechanical characteristics of this coating (little coating) as well as the morphology of the interface coating / support, are poorly suited for the neutralization of asbestos construction support.

 Furthermore, patent BE-B-580948 discloses a method for waterproofing building materials and more particularly asbestos cement sheets containing free lime. To do this, silicones and a silicone substance are applied to these materials with respect to free lime, namely a protective substance chosen from copolymers of esters of acrylic or methacrylic acids and styrene, a-methylstyrene or vinyl toluene. The silicones used are in the form of an emulsion of methyl, ethyl, propyl, butyl, amyl or phenyl benzyl polysiloxane or mixtures thereof. According to this patent, silicone / acrylic coatings are formed on asbestos cement sheets after drying. The silicones used are not crosslinked silicone elastomers. Therefore, the mechanical properties of these coatings are relatively poor and do not give them the ability to effectively fight against the spread of asbestos dust.

They are waterproofing coatings and the water repellency function is very different from the protection function against asbestos pollution.

 The French patent application FR-A-2190170 also discloses a process for the waterproofing of construction materials, in particular asbestos-cement by the use of an aqueous solution of alkali metal organosiliconates which are employed in the form of a solution intended to to impregnate the support to be water-repellent, another impregnation being performed using an aqueous solution of carbonate or hydrogencarbonates water-soluble.

The water-repellent coating according to document FR-A-2 190 770 does not necessarily have the mechanical and in particular the elastic qualities required to constitute an effective brake against the spread of asbestos dust in the atmosphere.

 Thus, it is clear that the prior art does not provide a satisfactory solution, in terms of surface treatment, for the neutralization of asbestos

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 as a component of old building materials and building elements.

 Under these conditions, one of the essential objectives of the present invention is therefore to propose a support surface treatment method containing asbestos and forming part of buildings, which process must be easy to implement. work, economic, little or no risk for the operators responsible for its implementation and in particular do not require heavy means of protection, in short it is important that this process is compatible with a procedure of cleaning and / or renovation of structures asbestos building (eg roof) falling within the routine.

 Another essential objective of the invention is to propose a surface treatment support support of construction which leads to the production of a film or a surface coating with mechanical properties and in particular elastic perfectly adapted to the morphology and the topolography of old asbestos construction media, ie possibly cracked and / or having irregularities of relief, and in doing so said coating ensuring at best its screen function against the inadvertent spread of asbestos dust of the treated support.

 Another essential object of the invention is to provide a support surface treatment method that can easily be applied to the old building media very fouled, for example requiring only a quick pre-cleaning with the aid of pressurized water in particular, said method then comprising the spreading on the cleaned support of a curable formulation in liquid or semi-liquid form so as to perfectly marry the support.

 Another object of the invention is to provide a clean surface treatment method to neutralize asbestos contained in building materials and thus to be non-eco-toxic not only in terms of the result but also when it is put implemented.

 Another essential objective of the invention is to provide a method of surface treatment of asbestos-containing supports making it possible to avoid the uncontrolled dispersion of asbestos in the atmosphere and not requiring the use of

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 mechanical reinforcement means of the interlining type, especially at the level of frequent cracks on asbestos structures of old buildings.

 Another essential object of the invention is to provide a method of surface treatment of asbestos construction supports making it possible to obtain a continuous coating of said support and in particular surface asbestos fibers, so as to prevent any dissemination of this asbestos in the atmosphere.

 Another essential object of the invention is to provide a method of renovating old construction structures containing asbestos, such as roofing, this method not only preventing the dispersion of asbestos in the air but also to protect and seal the structures thus treated.

 Another essential object of the invention is to provide a support containing asbestos and forming part of a building, this support being treated in such a way that it can not let asbestos dust escape the atmosphere.

 These objectives, among others, have been achieved by the inventors, who have had the merit of selecting and developing, after numerous studies and experiments, a method of treating a support surface with an aqueous dispersion using an aqueous dispersion. harmless silicone easily applicable to the substrates to be treated and leading to a cured coating by polymerization and / or crosslinking which forms a continuous and uniform elastic envelope, opposing any spread of asbestos dust into the atmosphere.

 From which it follows that the invention relates first of all to a method of surface treatment of a support containing asbestos and forming part of a building characterized in that it essentially consists of: applying to the support at least one layer of a curable, extendable, silicone composition comprising at least one aqueous dispersion of silicone oil (s) comprising: -A- 100 parts by weight of at least one polyorganosiloxane oil (A) capable of crosslinking by condensation, if necessary in the presence of a crosslinking agent (B), into an elastomer;

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 If necessary, from 0.1 to 100 parts by weight of at least one crosslinking agent (B); -C- optionally, up to 50 parts by weight of at least one adhesion promoter (C) - preferably a silane-; Up to 200 parts by dry weight of a filler (D); A catalytically effective amount of a catalytic curing compound (E) of up to 3 parts by weight; At least one emulsifier (F); -G- optionally at least one functional additive (G); -H- and water; and curing this (or these) layer (s) of drying and polymerization / crosslinking so as to form a waterproof silicone elastomeric coating adhering to the support and preventing the spread of asbestos out of the support.

 According to the process according to the invention, it is recommended to use a liquid or semi-liquid precursor, preferably a single component, of a silicone elastomeric coating in an aqueous phase, for the renovation of asbestos-containing building materials, such as roofing or building roofing elements, among others.

 The inventive choice of a silicone elastomeric product in aqueous phase, semi-thick ready to use and easily applied in layer (s) including spreading or brush, with a brush, with a spatula or with a roller or even by spraying, proves particularly suitable for the neutralization of the asbestos nuisance power in old buildings.

 After crosslinking, the applied coating forms a film of exceptional strength and elasticity that does not peel or crack. It has excellent resistance to ultraviolet aging and soiling.

In addition, the selected coating adheres without primer on a wide variety of building and roof supports: metals, wood (raw or treated), bituminous screed, tiles, concrete ...., without heating or gluing. It maintains a high level of elasticity despite climate variations. It does not harden cold weather and is not or hardly affected by temperature variations, for example from -50 ° C to + 120 ° C. It is also stable with respect to external chemical attack. The

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 ease of use is also an interesting quality of the selection made according to the invention. Indeed, the aqueous silicone dispersion retained is the hardened crosslinked coating or film that is derived from it can be easily and quickly implemented safely. The cross-linking drying is done without the release of odor or toxic chemicals and the cleaning of the tools is done simply with water. This product does not contain volatile organic compounds. Finally, these mechanical properties and its ability to perfectly coat the support and in particular the surface asbestos fibers make it possible to obtain a protection cover that is asper- taneous and self-adhesive after complete polymerization / crosslinking. This coating is an impassable screen for asbestos particles. Even the presence of cracks, roughness roughness irregularities on the treated substrate can not cause cracking of the coating because of its elasticity.

In fact, the coating obtained by the surface treatment according to the invention makes it possible to bind or fix the carrier asbestos fibers dangerous to health.

The silicone screen thus formed is not only effective against the dispersion of asbestos in the air but is a very good waterproof protection of the treated substrate.

 Traditional coatings of building materials or building elements, for example coatings obtained from liquids formed by acrylic latices are far from having all the properties stated above.

 The building materials or building elements considered in the present invention can be for example those constituting walls, facades, ceilings, floors, roofs, etc ... These materials or these elements of construction can be presented under forming plates, bricks, blocks assembled or unassembled. As regards their constitution, these materials or support elements may be based on lime and / or silica or plaster silicate, that is to say coating for walls based on sand and mineral substances with hydraulic setting and / or non-hydraulic such as lime, cement and / or plaster, as well as walls of parts formed from concrete, brick, natural stone, tile, slag brick, calcium-silicate materials, between others, with the consistent presence of asbestos and more specifically harmful asbestos fibers.

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 According to an advantageous characteristic of the invention, the application of the silicone composition that is extendible and hardenable on the support is carried out by spraying and / or spreading by means of a tool consisting of a brush and / or a brush and / or or a roller and / or a spatula.

 It is of particular interest to be able to apply the aqueous silicone dispersion by spraying in the case where the treated supports are large surfaces as may be the case for roofs made of cement fiber cementant. It is preferably a spray gun spray.

 In the case where the host support is particularly dirty, it may be wise to implement a prior step of cleaning the support before the application of the aqueous silicone dispersion.

 It has been established according to the invention that the asbestos dispersion screen function is perfectly expressed when the silicone elastomer coating is made to have a thickness of between 0.1 and 10. mm, preferably between 0.15 and 5 mm, and more preferably between 0.2 and 3 mm.

 The fact that the aqueous silicone starting composition is advantageously monocomponent contributes to the simplicity of implementation of the process.

 The silicone composition selected is an aqueous dispersion based on viscous silicone oil crosslinkable elastomer by removal of water (condensation).

 More specifically, this aqueous silicone dispersion is advantageously of the type described in PCT application WO-A-02/00770.

 In the context of the present invention, however, it can be specified with regard to the oil (A) that the viscosity of its silicone phase () is # 10 Pa.s, preferably at 50 Pa.s and more preferably at 70 Pa. s. The viscosity considered was determined for example using a Brookfield viscometer according to AFNOR standard NFT76102 of 02.02.1972.

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Avantageusement, les huiles (A) sont des huiles #,ro-hydroxylées ou des huiles fonctionnelles comportant par molécule au moins 2 groupes fonctionnels condensables éventuellement après hydrolyse.

Advantageously, the oils (A) are #, hydroxylated or functional oils comprising, per molecule, at least 2 condensable functional groups, optionally after hydrolysis.

formule dans laquelle : - a est 0 ou 1, - b est 0 ou 1, - avec a + b = 0 ; 1 ou 2, - n a une valeur suffisante pour conférer au polymère de formule (a) la viscosité désirée, - les radicaux R sont identiques ou différents et représentent un groupe OH avec a+b = 2 ; un groupe alcoxy ou alcényloxy contenant de 1 à 10 atomes de carbone ; un groupe aryloxy contenant de 6 à 13 atomes de carbone ; un groupe acyloxy contenant de 1 à 13 atomes de carbone ; un groupe cétiminoxy contenant de 1 à 8 atomes de carbone ; un groupe amino- ou amido-fonctionnel contenant de 1 à 6 atomes de carbone, liés au silicium par une liaison Si-N ; - les radicaux R1 et R2sont identiques ou différents et représentent des groupes organiques aliphatiques alkyle, alcényle, ayant de 1 à 10 atomes de carbone, aromatiques phényle, lesdits groupes étant éventuellement substitués par des atomes d'halogènes ou des groupes cyano ; - les radicaux R3et R4sont identiques ou différents et représentent des groupes organiques aliphatiques alkyle, aminoalkyle, polyaminoalkyle, époxyalkyle, alcényle, contenant de 1 à 13 atomes de carbone, aromatiques aryle contenant de 6 à 13 atomes de carbone ; More precisely, these oils (A) can be represented by the following generic formula (I):

wherein: - a is 0 or 1, - b is 0 or 1, - with a + b = 0; 1 or 2, - has a sufficient value to give the polymer of formula (a) the desired viscosity, - the radicals R are identical or different and represent an OH group with a + b = 2; an alkoxy or alkenyloxy group containing from 1 to 10 carbon atoms; an aryloxy group containing from 6 to 13 carbon atoms; an acyloxy group containing from 1 to 13 carbon atoms; a cetiminoxy group containing from 1 to 8 carbon atoms; an amino or amido-functional group containing from 1 to 6 carbon atoms bonded to silicon by an Si-N bond; the radicals R 1 and R 2 are identical or different and represent alkyl, alkenyl, aliphatic organic groups having from 1 to 10 carbon atoms, phenyl aromatics, said groups optionally being substituted by halogen atoms or cyano groups; the radicals R 3 and R 4 are identical or different and represent alkyl, aminoalkyl, polyaminoalkyl, epoxyalkyl, alkenyl, aliphatic organic groups containing from 1 to 13 carbon atoms, aryl aromatics containing from 6 to 13 carbon atoms;

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 at least 2 condensable functional groups optionally after hydrolysis being present per molecule of at least 80% of the radicals R1 to R4 representing a methyl group.

#. aminofonctionnels tels que par exemple éthylamino, phénylamino ; #. amidofonctionnels tels que par exemple méthylacétamido ; Parmi les radicaux organiques aliphatiques ou aromatiques mentionnés ci-dessus, on peut citer en ce qui concerne
R1, R2 : par exemple les groupes méthyle, éthyle, octyle, trifluoropropyle, vinyle, phényle ;
R3, R4 . par exemple les groupes méthyle, éthyle, octyle, vinyle, allyle, phényle ; -(CH2)3-NH2 ; -(CH2)3-NH-(CH2)2-NH2 ; A titre d'exemples concrets de motifs D : R1R2SiO2/2 présents dans l'huile (A) on peut citer: (CH3)2Si02/2 ; CH3(CH2 = CH)Si02/2 ; CH3(C6H5)Si02/2 (C6H5)2Si02/2 A titre d'exemples concrets de motifs M :RR3R4SiO1/2 on peut citer : (CH3)2(OH)SiOi/2 ; (OCH3)3SiO1/2 ; [O-C(CH3) = CH2]3SiO1/2

[ON=C(CH3)]3SiOi/2 ; (NH-CH3)3SiOnz ; (NH-CO-CH3)3SiOi/2. By way of example of R radicals, mention may be made of: # alkoxy groups such as for example methoxy, ethoxy or octyloxy; alkenyloxy such as for example vinyloxy, hexenyloxy, isopropenyloxy; aryloxy such as, for example, phenyloxy; acyloxy such as for example acetoxy; # cetiminoxy such as for example ON = C (CH3) C2H5;

#. aminofunctional such as for example ethylamino, phenylamino; #. amidofunctional agents such as, for example, methylacetamido; Among the aliphatic or aromatic organic radicals mentioned above, mention may be made of
R1, R2: for example methyl, ethyl, octyl, trifluoropropyl, vinyl, phenyl;
R3, R4. for example, methyl, ethyl, octyl, vinyl, allyl, phenyl; - (CH2) 3 -NH2; - (CH2) 3-NH- (CH2) 2 -NH2; As concrete examples of D: R 1 R 2 SiO 2/2 units present in the oil (A), mention may be made of: (CH 3) 2 SiO 2/2; CH3 (CH2 = CH) SiO2 / 2; CH3 (C6H5) SiO2 / 2 (C6H5) 2SiO2 / 2 As concrete examples of M: RR3R4SiO1 / 2 units, mention may be made of: (CH3) 2 (OH) SiO1 / 2; (OCH3) 3SiO1 / 2; [OC (CH3) = CH2] 3SiO1 / 2

[ON = C (CH 3)] 3 SiO 1/2; (NH-CH3) 3SiOnz; (NH-CO-CH3) 3 SiO / 2.

polymère a,eo-(dihydroxy)polydiorganosiloxane. De nombreux agents de réticulation peuvent être utilisés selon des quantités fonctions de leur nature ; ceux-ci sont bien connus de l'homme de l'art. A crosslinking agent (B) must be used when the oil (A) is a

α, β- (dihydroxy) polydiorganosiloxane polymer. Many crosslinking agents can be used in function quantities of their nature; these are well known to those skilled in the art.

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By way of example, a list of crosslinking agents with the corresponding recommended quantities, expressed in parts by weight per 100 parts of oil (A), is given below:
0.5 to 10 parts of sodium silicate,
0.1 to 15 parts of an alkali metal organosiliconate (European Patent EP-A-266 729),
1 to 100 parts of a microemulsion of silsesquioxane resin (US-A-3,355,406; 433,780),
5 to 100 parts of a low molecular weight reactive silicone resin having alkoxy and acyloxy groups (US-A-4,554,187),
5 to 100 parts of a high-toluene-insoluble silicone resin (EP-A-304,719),
5 to 100 parts of a hydroxylated silicone resin consisting of units of formulas R'3SiO1 / 2 (M) and / or R'2SiO2 / 2 (D), combined with units of formulas R'SiO3 / 2 (T) and or SiO 2 (Q), R 'being mainly a C 1 -C 6 alkyl, vinyl and 3,3,3-trifluoropropyl radical and a hydroxyl content by weight of between 0.1 and 10%. Among these resins, mention may be made especially of MQ resins, MDQ,
CT, TD (FR-A-2,638,166).

 1 to 20 parts of a silane of formula: (R ") u Si X (4-u) in which R" is a monovalent organic radical, in particular methyl or vinyl, u is 1 or 0, X is a condensable and / or organic hydrolysable group of the same definition as the radical R of formula (I) above (alkoxy, alkenyloxy, acyloxy, cetiminoxy, alkylamino, alkylamido silanes described in particular in US Pat. No. 3,294,725; 584,341; 618,642; US-A-4,608,412; 525,565; EP-A-387157; EP-A-340,120; EP-A-364,375; 248,826; FR-A-1023,477.

By way of examples, mention may be made of the following alkoxysilanes:
If (OC2H5) 4; CH3Si (OCH3) 3; CH3Si (OC2H5) 3; (C2H50) 3Si (OCH3);
CH2 = CHSi (OCH3) 3; CH3 (CH2 = CH) Si (OCH3) 2;
CH2 = CH (OC2H5) 3;
CH2 = CHSi [ON = C (CH3) C2H5]; CH3Si [ON = C (CH3) 2] 3
CH3 Si [-C (CH3) = CH2] 3;

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 methyltri (N-methylacetamidosilane); methyltris (cyclohéxylaminosilane).

 The adhesion promoters (C) are preferably silanes These silanes (C) optionally present in the composition of the dispersions of the invention are additives for modulating the physicochemical properties of the silicone elastomer compositions obtained after crosslinking the dispersions forming the object of the invention.

The silane by-products of the synthesis reaction of the oils (A) can be represented by the formula: (R 5) c Si (R) 4-c in which: - c is 0; 1 or 2, - the radicals R 5, identical or different, correspond to the radicals R3 and R4 of the oil (A) of formula (1), - the radical R corresponds to the organic radical R of the polyorganosiloxane oil (A) of formula (1).

By way of examples of such silanes, mention may be made of the crosslinking silanes mentioned above. They are generally present in amounts of the order of 0 to 10 parts by weight, preferably of the order of 0 to 5 parts by weight per 100 parts of oil (s) (A).

The silane modulating additives of physicochemical properties, may especially be adhesion agents such as those described in patent application EP-A-340 120. Aminopropyltriethoxysilane, aminopropylmethyldiethoxysilane, may be mentioned in particular; glycidoxypropyltrimethoxysilane. They are used in amounts of up to 50%, generally of the order of 0.5 to 10% by weight of oil (s) (A).

 According to a preferred arrangement of the invention, the filler (D) is selected from the group of hydrophilic compounds comprising: CaCO 3, SiO 2, TiO 2, Al 2 O 3 / H 2 O, emulsion organic (co) polymer (s) and mixtures thereof .

These hydrophilic compounds capable of constituting the particulate solid filler (D) can be obtained by precipitation in a liquid and / or by grinding.

In the case where it is particulate charge (D) obtained by precipitation, it is possible that the latter intervene in the water. An aqueous colloidal suspension of charge (D), which can be used for the preparation of the dispersion according to the invention, is then directly available.

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According to one variant, this suspension can be obtained by incorporating the pulverulent dry charge (D) into the water.

For example, slurries of precipitated CaCOa or ground CaCO3 exist.

Silica SiO 2 may be colloidal silica, precipitated silica or fumed silica.

The term "colloidal silica" denotes a stable suspension of differentially-sized, substantially spherical silica particles of size between 0.00001 to 0.1 m, preferably between 0.001 and 0.05 m.

The organic emulsion copolymers are more commonly known under the names "LATEX" or "NANOLATEX". These are for example aqueous dispersions of polymer particles from conventional methods of co (emulsion polymerization of one or more polymerizable organic monomers.

According to one variant, the dispersions used in the process according to the invention may comprise, in addition to the hydrophilic filler (D) provided in the form of an aqueous colloidal suspension, a filler (D ') which is involved in the process of obtaining the dispersion, in pulverulent form. This charge (D ') brought into powder in the mixture leading to the dispersion is distinguished from the load (D) hydrophilic dry, through its specific surface area Ss (m2 / g) which is reduced, namely:
Ss <5 preferably Ss # 3 Examples of pulverulent fillers (D ') include: CaCO 3, SiO 2, TiO 2, Al 2 O 3 / H 2 O.

 Advantageously, the filler (D ') may represent 5 to 100 parts by dry weight per 100 parts by weight of silicone phase cps.

 Catalytic hardening compounds (E) are well known to those skilled in the art; these are the carboxylic acid salts and metal halides such as, for example, lead, zinc, zirconium, titanium, iron, barium, calcium, manganese and especially tin.

There may be mentioned: the reaction products of tin dicarboxylates and ethyl polysilicate (US-A-3,862,919), the reaction products of dibutyltin diacetate and an alkyl silicate or an alkyltrialkoxysilane (BE-A-842 305),

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 tin bischelates (EP-A-147,323; 235,049), diorganotin dicarboxylates (GB-A-1,289,900).

They can be used in amounts of up to about 3 parts by weight, preferably in the region of 0.05 to 1 part by weight per 100 parts of oil (A).

 The emulsifiers (F) used may be ionic or non-ionic surfactants or water-soluble polymers.

Preferably, they are nonionic surfactants. By way of examples, mention may be made of alkoxylated fatty acids, polyalkoxylated alkylphenols, polyalkoxylated fatty alcohols, polyalkoxylated or polyglycerolated fatty amides, polyglycerolated alcohols and alpha diols, ethylene oxide-propylene oxide block polymers, and alkylglucosides, alkylpolyglucosides, sucroethers, sucroesters, sucroglycerides, sorbitan esters and ethoxylated compounds of these sugar derivatives.

According to one variant, the emulsifiers (F) are selected from anionic surfactants such as, for example, alkylbenzene sulphonates, alkyl sulphates, alkyl ether sulphates, alkylarylethersulphates, dioctylsulphosuccinates, and alkali metals.

a,#bis(hydroxy)polydiméthylsiloxane. The (mixture of) emulsifier (s) is chosen according to the nature of the silicone oil (A) to be emulsified; an HLB of the order of 11 to 15 is generally chosen to emulsify a silicone oil (A) constituted by a polymer

a, # bis (hydroxy) polydimethylsiloxane.

The weight ratio water / water + emulsifier (s) (F) is a function of the viscosity of the silicone phase (cps) and the nature of the (mixture of) surfactant (s); The ratio is, for example, of the order of 20/100 to 70/100, preferably of the order of 25/100 to 60/100, for stabilizing an emulsion of a silicone phase consisting of an [alpha], # -dihydroxylated viscosity of the order of 30 to 500 Pa, using a nonylphenol having 9 or 10 ethoxy units as sole emulsifier (F).

 As regards the other functional additives (G) that may be used, they are, in particular, plasticizers and / or salts and / or thickeners and / or charge dispersants, the latter being preferably selected from the group of products with hydrophilic function (s) anionic (s) and more preferably still in the group comprising polyacrylates and / or (poly) phosphates.

These additives can also or more precisely be:

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 plasticizers such as, for example, polydimethylsiloxane oils with a viscosity of the order of 300 to 10,000 mPa. dioctyl phthalates, dialkylbenzenes optionally in aqueous emulsion, in amounts of 0 to 70 parts by weight per 100 parts by weight of oil (A); thickening agents such as water-soluble polymers with a molecular mass greater than 10,000 g / mol, such as, for example, alkali metal polyacrylates, polyvinyl alcohols, polyethylene glycols, polyvinylpyrrolidones, carrageenans, alginates, methylcelluloses and hydroxyalkylcelluloses; xanthan gum in amounts of up to 10% by weight of the final aqueous dispersion; charge dispersants such as, for example, alkali metal polyacrylates having a molecular weight of less than 5,000; inorganic phosphates in amounts of up to 10% by weight of the final aqueous dispersion; optionally inorganic or organic pigments in an amount of less than 4%, preferably 2% by weight relative to the total mass of the dispersion.

These additives (G) may be introduced either into the silicone phase before it is emulsified or to the emulsion before dilution.

 In practice, the silicone phase (cps) of the dispersion used in the surface treatment according to the invention consists of: - (# s1) an oil (A) with a viscosity of at least 10 Pa.s, - ( cps2) a mixture of oils (A), a mixture of viscosity of at least 10 Pa.s, - (cps3) a mixture of at least one oil (A) and at least one crosslinking agent (B) if this is necessary and / or a silane (C), a viscosity mixture of at least 10 Pa.s, - or (cps4) a mixture of at least one oil (A) and the catalytic compound (E), optionally in the presence of at least one silane (C).

More preferably still this silicone phase <ps consists of: - (# s1) an oil (A) with a viscosity of the order of 50 to 1000 Pa.s, - (cps2) a mixture of oils (A), mixture viscosity of the order of 50 to
1000 Pa.s, - (cps3) a mixture of at least one oil (A) and at least one crosslinking agent (B) if this is necessary and / or a silane (C), a viscosity mixture in the range of 50 to 1000 Pa.s,

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 or (cps4) a mixture of at least one oil (A) and the catalytic compound (E), optionally in the presence of at least one silane (C).

 Regarding the preparation of the silicone aqueous dispersion selected according to the invention, reference is made for more details in PCT application WO-A-02/00770.

 According to another of its aspects, the present invention relates to a support containing asbestos and forming part of a building characterized in that it comprises a hardened polymer surface coating, sealed, adhering to the support and preventing the dispersing the asbestos out of the support asbestos, this polymer being cured by drying and polymerization / crosslinking and preferably selected from the group comprising polyesters, epoxy resins, poly (meth) acrylics, polyurethanes, silicones or their mixtures and / or copolymers.

 Preferably, the cured polymer surface coating is a silicone elastomer coating, preferably of the type obtained from a silicone dispersion.

 To best ensure its role of screen against the spread of asbestos dust, the silicone elastomer coating has a thickness of between 0.1 and 10 mm, preferably between 0.15 and 5 mm, and more preferably between 0, 2 and 3 mm.

The examples are given for information only and can not be considered as a limit of the scope and spirit of the invention.

EXAMPLES Example 1 1.1 Preparation of a First Crosslinkable Aqueous Silicone Dispersion (ABCDEFGH): a) In a 2 # anchor mixer, 347.7 g of hydroxylated polydimethylsiloxane oil of viscosity 135,000 mPa.s, -A'-

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26.2 g of polydimethylsiloxane oil blocked with methyl groups of viscosity 100 mPa.s, -B- 3.7 g of hydroxylated MDT resin with viscosity
1000 mPa.s (containing 0.5% by weight of hydroxyl groups, 62% by weight of trifunctional units, 24% by weight of di-functional units and
14% by weight of mono-functional units) 26.4 g of Rhodasurf ROX (85% aqueous solution of a polyethoxylated C13 aliphatic alcohol containing approximately 8 oxyethyl units) and 7.9 g of water demineralized. b) Mix at 100 rpm until a fine O / W emulsion (average diameter 0.6 m) is obtained. c) Dilute with 8.2 g of demineralised water and then add, with stirring to
100 rpm, -D- 7.9 g of V5639 precolor pigment marketed by
Wunsiedel predispersed in 9 g of sodium polyacrylate - dispersant sold by Coatex under the name Coatex P50 or by Protex under the name Prox A11 - and-C - 24.3 g of an aqueous solution containing 77% by weight of a resin T (OH) with aminopropyl groups sold by WITCO under the name VS 142. d) 186.9 g of crushed calcium carbonate sold by OMYA under the name BLR3 are dispersed in the mixture thus obtained;
186.9 g of precipitation carbonate marketed by Solvay under the name Socal 312, with stirring at 100 rpm. e) Finally, 0.4 g of antifungal agent is introduced and then 9 g of demineralized water and 1.2 g of a solution containing 60% by weight of dioctyltin dilaurate are added and the mixture is stirred. under vacuum (4600 Pa) with moderate agitation of 100 rpm.

The dry extract of such a formula is 79%.

1 .2 / Implementation of the process according to the invention: The aqueous dispersion prepared in 1. 1 is applied to the brush (brush type) on an asbestos-cement plate, without prior cleaning. The deposited thickness is about 1 mm. The product is allowed to dry for 7 days at 23 ° C. and it is found that the elastic silicone coating obtained has an acceptable adhesion on the support. The layers of asbestos dangerous for health have been coated and covered with an inert layer of silicone elastomer. The fiber cement sheet thus treated no longer poses a risk of release of asbestos dust and therefore no longer presents any danger.

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Example 2 2. 1 / Preparation of a Second Crosslinkable Aqueous Silicone Dispersion (ABCEFH): a) Introduction: # of 33.5 kg of oil (A) 48 V 135,000 of RHODIA SILICONES (α, α-dihydroxylated polydimethylsiloxane silicone oil , viscosity = 135,000 mPa.s, titrating about 300 ppm OH by weight), # of 1,843 kg of a hydroxylated silicone resin - crosslinking agent (B) - (RHODIA SILICONES Resin (B), patterned MDT, at 0.5% by weight of OH group, and consisting of 62% by weight of T (CH 3 SiO 3/2) units,
24% by weight of D [(CH 3) 2 SiO 2/2] units and 14% by weight of M [(CH 3) 3 units
SiO1 / 2]), # of 1.575 kg of Rhodasurf ROX - surfactant (F) - (85% aqueous solution of ethoxylated fatty alcohol of RHODIA), # and 0.52 kg of demineralized water (H), in the tank of a 100-liter Neulinger planetary mixer (equipped with a butterfly-type stirrer and a planetary dispersing arm, as well as a scraping stirrer). b) Stirring for 60 minutes with a speed of 400 rpm for the butterfly-type stirrer and 42 rpm for the scraping stirrer. c) Obtaining a silicone / water emulsion having a mean particle size of
567 nm (measured Coulter LS 130 from Coultronics). The mass temperature reached 45 C. d) Gradual dilution of the emulsion by introducing in 15 min 12,507 kg of demineralised water (H) with stirring (butterfly at 400 rpm and scraped at 21 rpm). e) Compounding: The temperature is 35 C. After reduction of the stirring speed of the butterfly introduction in 2 min of 1 kg of silquest VS142 of
WITCO - adhesion promoter (C) - (aqueous solution at about 25% of amino silane) and in 15 min of 46.9 kg of a 72% aqueous dispersion of

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CaCO 3 charge (D) (OMYACOAT 80 from the company OMYA). The temperature is 29 C.

0.109 kg of an aqueous emulsion titrating 38% of dioctyltin dilaurate stabilized with polyvinyl alcohol-catalyst (E) - (Rhodia 70827 A emulsion) is finally added, and the stirring speeds of the butterfly and the doctor blade is respectively 200 and 42 rpm.

The dispersion thus obtained is then degassed by stirring under the same conditions for 10 min under a vacuum of 150 mbar and then packaged in containers impervious to water vapor. It has a dry extract of 72%.

2. 2 / Implementation of the Process According to the Invention The dispersion prepared in 2.1 is applied by spraying it onto an asbestos cement plate, without prior cleaning. Firstly, a first coating layer 4000 is deposited, then after about 1 hour of drying, a second layer is applied under the same conditions. The total thickness deposited is about 0.3 mm. The product is allowed to dry for 7 days at 23 ° C. and it is found that the elastic silicone coating obtained has an acceptable adhesion on the support. The layers of asbestos dangerous for health have been coated and covered with an inert layer of silicone elastomer. The fiber cement sheet thus treated no longer poses a risk of release of asbestos dust and therefore no longer presents any danger.

Claims (17)

 1) A surface treatment method of a support containing asbestos and used in the constitution of a building characterized in that it consists essentially: # to apply on the support at least one layer of a silicone composition extensible, curable and comprising at least one aqueous dispersion of silicone oil (s) comprising: -A- 100 parts by weight of at least one polyorganosiloxane oil (A) capable of crosslinking by condensation, if necessary in the presence of an agent crosslinking (B), an elastomer; If necessary, from 0.1 to 100 parts by weight of at least one crosslinking agent (B); -C- optionally, up to 50 parts by weight of at least one adhesion promoter (C) - preferably a silane-; Up to 200 parts by dry weight of a filler (D); A catalytically effective amount of a catalytic curing compound (E) of up to 3 parts by weight; At least one emulsifier (F); -G- optionally at least one functional additive (G); -H- and water; and curing this (or these) layer (s) of drying and polymerization / crosslinking so as to form a waterproof silicone elastomeric coating adhering to the support and preventing the spread of asbestos out of the support. 2) Method according to claim 1, characterized in that the application of the silicone composition extendable and curable on the support is carried out by spraying and / or spreading using a tool consisting of a brush and / or a brush and / or a roller and / or a spatula. 3) Process according to claim 1 or 2, characterized in that it implements a step of cleaning the support prior to the application of the aqueous dispersion. <Desc / Clms Page number 21>  5 10 15 20 25 30 35 4) Process according to any one of claims 1 to 3, characterized in that it is made so that the silicone elastomer coating has a thickness of between 0.1 and 10 mm, preferably between 0.15 and 5 mm and more preferably between 0.2 and 3 mm. 5) Process according to claim 1, characterized in that the oils (A) are [alpha], # - hydroxylated oils or functional oils comprising per molecule at least 2 condensable functional groups optionally after hydrolysis. 6) Process according to claim 1 or 5, characterized in that the oils (A) have the generic formula (I)

 wherein: - is 0 or 1, - b is 0 or 1, - with a + b = 0; 1 or 2, n is of sufficient value to give the polymer of formula (a) the desired viscosity; the radicals R are identical or different and represent: an OH group with a + b = 2; an alkoxy or alkenyloxy group containing from 1 to 10 carbon atoms; an aryloxy group containing from 6 to 13 carbon atoms; an acyloxy group containing from 1 to 13 carbon atoms; a cetiminoxy group containing from 1 to 8 carbon atoms; an amino or amido-functional group containing from 1 to 6 carbon atoms bonded to silicon by an Si-N bond; the radicals R 1 and R 2 are identical or different and represent alkyl, alkenyl, aliphatic organic groups having from 1 to 10 carbon atoms, phenyl aromatics, said groups optionally being substituted by halogen atoms or cyano groups; <Desc / Clms Page number 22>  the radicals R3 and R4 are identical or different and represent alkyl, aminoalkyl, polyaminoalkyl, epoxyalkyl or alkenyl organic groups containing from 1 to 13 carbon atoms, aryl aromatics containing from 6 to 13 carbon atoms; at least 2 condensable functional groups optionally after hydrolysis being present per molecule. 7) Process according to claim 6, characterized in that at least 80% of the radicals R1 to R4 representing a methyl group. 8) Process according to claim 1, characterized in that the crosslinking agent (B) is sodium silicate, an alkali metal organosiliconate, a silsesquioxane resin microemulsion, a low molecular weight reactive silicone resin having alkoxy groups and acyloxy, a toluene insoluble high-molecular silicone resin, a hydroxylated silicone resin, an alkoxysilane, an alkylaminosilane, an alkylamidosilane. 9) Process according to claim 1, characterized in that the adhesion promoter, preferably the silane (C), has the formula: (R5) c Si (R) 4.c in which formula: - c is 0; 1 or 2, the radicals R5, which are identical or different, correspond to the radicals R3 and R4 of the oil (A) of formula (1), the radical R corresponds to the organic radical R of the polyorganosiloxane oil (A) of formula (1), - said silane being present in amounts of the order of 0 to 10 parts by weight per 100 parts of oil (s) (A). 10) Process according to claim 9, characterized in that the adhesion promoter, preferably the silane (C), is an adhesion modulating additive such as aminopropyltriethoxysilane, aminopropylmethyldiethoxysilane, glycidoxypropyltrimethoxysilane, present according to amounts up to 50% of the weight of oil (s) (A). <Desc / Clms Page number 23> SiO 2, TiO 2, Al 2 O 3 / H 2 O, organic (co) polymer (s) in emulsion and mixtures thereof.  11) Process according to claim 1, characterized in that the charge (D) is selected from the group of hydrophilic compounds comprising: CaCOs, 12) Process according to claim 1, characterized in that the catalytic hardening compound (E) is a derivative of tin, used in amounts ranging from 0.05 to 1 part by weight per 100 parts of oil (A). 13) Method according to claim 1, characterized in that the aqueous dispersion is chosen such that its silicone phase (#s) consists of: - (# s1) an oil (A) with a viscosity of at least 10 Pa. s, - (# s2) a mixture of oils (A), a mixture of viscosity at least equal to 10 Pa.s, - ((ps3) a mixture of at least one oil (A) and at least one crosslinking agent (B) if this is necessary and / or a silane (C), viscosity mixture at least 10 Pa.s, or (cps4) a mixture of at least one oil (A) and the catalytic compound (E), optionally in the presence of at least one silane (C) or in: (# s1) an oil (A) with a viscosity in the range of 50 to 1,000 Pa.s, - (cps2) a mixture of oils (A), viscosity mixture of the order of 50 to 1000 Pa.s, - (cps3) a mixture of at least one oil (A) and at least one crosslinking agent (B) if this is necessary and / or a silane (C), a viscosity mixture of the order of 50 to 1000 Pa.s, or (cps4) a mixture of at least one oil (A) and the catalytic compound (E), optionally in the presence of at least one silane (C). 14) Process according to claim 1, characterized in that the selected aqueous dispersion additionally contains functional additives (G), plasticizers and / or thickeners and / or charge dispersants, the latter being preferably selected from the group of products with hydrophilic function (s) anionic (s) and more preferably still in the group comprising polyacrylates and / or (poly) phosphates. <Desc / Clms Page number 24>  15) Support containing asbestos and forming part of a building, characterized in that it comprises a hardened polymer surface coating, sealed, adhering to the support and preventing the spread of asbestos out of the support l asbestos, this polymer being cured by drying and polymerization / crosslinking and preferably selected from the group consisting of polyesters, epoxy resins, poly (meth) acrylics, polyurethanes, silicones or their mixtures and / or copolymers. 16) Support according to claim 15, characterized in that the cured polymer surface coating is a silicone elastomer coating, preferably of the type obtained from a silicone dispersion as defined in claims 2 to 15. 17) Support according to claim 15 or 16, characterized in that the silicone elastomer coating has a thickness of between 0.1 and 10 mm, preferably between 0.15 and 5 mm, and more preferably between 0.2 and 3 mm .