FR2477565A1 - External building wall protective compsn. - contg. scleroprotein-derived enzymatically active metallo-protein and pref. polysiloxane-forming retention agent polymerisable in situ - Google Patents

Abstract

Treatment compsn for protecting external-, esp limestone- contg walls, contains, in aq. soln., (i) pref 0.001-0.02 (0.008) wt %, w.r.t total compsn.,of enzymatically active metallo- proteins, (I) and (ii) pref 5-50 (10) wt % retention agent, (II), capable of polymerising in air at ambient temps. The (I)-forming aminoacids are derived from scleroproteins, esp keratin. (I) have isoelectric point zero and catalyse the reversible reaction of H2CO3 to CO2 and H2O. (II) retain (I) in the wall surface layer, where they are allowed to penetrate. The compsn protects walls against erosion by weathering and chemical degradation. (I) activate bicarbonate dissociation and promote the formation of crystalline, white aragonite, which is meta-stable form of limestone. (I) are produced economically, on a large scale, and in high yields, as opposed to the similarly acting carbonic acid anhydrase.

Description

COMPOSITION FOR THE PROTECTION OF EXTERIOR WALLS WITH A BUILDING 1 'AND CORRESPONDING METHOD
The present invention relates to a composition intended to be applied against the external walls of a building in order to protect, for example, cut stones, millstones, cement plasters, asbestos-cement agglomerates which constitute them. , in short all building materials and in particular those containing calcium carbonate against the aggression of atmospheric agents
We know that most of the materials used in the construction of building facades and; consequently, intended to be exposed to the weather, are generally of a porous nature5 that is to say that they can absorb water, whether it is raw runoff water with capillarity pro coming from ambient humidity, this action of water combining; to that of carbon dioxide contained in the atmosphere to give rise to carbonic acid which gnaws and degrades stones. In the particular case of limestone-based materials, the infiltration water has the effect of dissolving the carbonates and thus gradually destroying the stones which, of course, can be particularly beneficial in the case of materials a monument remarkable for its archaeological, historical or aesthetic interest. To this purely chemical degradation of building materials is added a physical effect resulting from the infiltration of water in the materials, which can cause damage such as bursting and cracking due to freezing and thawing as well as large temperature variations
We have therefore been led to propose various treatment methods consisting, for the most part, of plugging the pores of the materials by a surface treatment in order to make them impermeable to water. However, such methods have the drawback not only of having only a limited action in time, thus imposing frequent applications, but also and above all of preventing IXrespirtion "of the materials by forming a barrier to the circulation of gases. from inside to outside of buildings.

To allow the protection of materials as well as their "breathing", the French patent 2 205 911i has already proposed a treatment composition composed of an aqueous alkaline solution of a siliconate, calcium bicarbonate and carbonic anhydrase. Although this is not specified in the French patent referred to above, it is known that carbonic anhydrase is a metalloprotein which catalyzes the reaction

 It is also known that this enzyme, the active metal of which is zinc, can be found, at relatively high concentrations, in the erythrocytes, the renal cortex and the gastric mucous membranes of mammals as well as in other animal tissues, plants and some bacteria.

 Carbonic anhydrase has already been isolated, in particular from erythrocytes (Lindskog, Biochim. BioDhys. Acta 39,218 (1960)) and from human erythrocytes (Nyman, Biochim.

 BiophyS, Acta 52, 1 (1961)). The aforementioned French patent does not specify the origin of the carbonic anhydrase used; he confines himself to mentioning carbonic anhydrase, without specifying the utility which it can have or the role which it can play in a composition for treating facade materials. Consequently, the skilled person cannot in any way, from the teaching of said patent, imagine that carbonic anhydrase can be replaced by another product and even less discover a substitute for carbonic hydrase, which would be obtained with a higher yield and a lower cost price.

The present invention aims to describe a composition intended for the treatment of materials entering into the constitution of the external walls of a building and in particular of materials containing limestone, the aforementioned composition having the characteristic of containing metallo-proteins different from the carbonic anhydrase but which, like it, have the property of catalyzing the reaction H2C 3 * -> C02 + H209
The metalloproteins entering into the composition according to the invention facilitate and activate the dissociation of bicarbonates and orient during the formation of limestones, the crystallization towards aragonite which is a metastable form of limestone, the calcareous deposits taking place more usually in the form of calcite. Such metallo-teats, whose structure has not yet been well defined, are distinguished, among others, from carbonic anhydrase, which is a natural enzyme having a comparable catalytic action, by the value of the isoelectric point and by the constitution of the chains, because the amino acids of the metalloproteins used in the invention come from scleroproteins, in particular from the keratin contained, in particular in the wool, the metalloproteins used in the present invention can eBe obtained in large quantities by a preparation process that can be carried out on an industrial scale, which makes it possible to obtain metallo-proteins both with a high yield and with a relatively basic cost price. thus it is possible to obtain approximately log of metalloproteins from a kg of raw wool, while the extraction of carbonic anhydrase from the modes indicated above is more the responsibility of the research laboratory. industry only.

la composition contenant, outre les métallo-protéines précitées, un agent de rétention, polymérisable à l'air et à la température ordinaire, destind à maintenir les métallo-protéines de la composition dans la couche superficielle de la paroi du bâtiment, où on les a fait pénétrer.the present invention therefore has for its object a composition for treating materials constituting the external walls of a building, in particular building materials containing limestone, characterized in that it contains; in aqueous solution, metalloproteins with enzymatic activity, the constituent amino acids of which come from scleroproteins, in particular keratin, said metalloproteins having a substantially zero isoelectric point and having the property of catalyzing the reaction

the composition containing, in addition to the aforementioned metalloproteins, a retention agent, polymerizable in air and at ordinary temperature, intended to maintain the metalloproteins of the composition in the surface layer of the building wall, where they are did penetrate.

 The metalloproteins used in the present invention are preferably prepared by the process described in French patent application 80 02074 filed on January 31, 1980; firstly, keratin fibers, preferably raw wool fibers, are brought into contact with an impregnating solution intended to prevent the lysis of the sulfur-containing amino acids forming part of the keratin fibers, and d1 is aimed at the keratin fibers as well impregnated in two substantially equal parts (A) and (B); secondly, the part (A) is dissolved in a solution of at least one easily oxidizable metal chloride, in concentrated hydrochloric acid: thirdly, the part (B) is dissolved in a concentrated base solution , in particular concentrated soda, the pH of which is close to or greater than 13; and fourthly, the two parts (A) and (B) are mixed so as to obtain a precipitate containing the desired metalloproteins.

 After having mixed the two parts (A) and (B)> which have each undergone the dissolution phase, the mixture is left to stand for approximately 24 hours, so as to be able to recover by filtration, preSerence, under vacuum the entire precipitate form. The precipitate is washed with a batten, allowed to dry and then rinsed again with ether to finally reduce it to powder.

 Preferably, it is this powder containing both the desired metalloproteins and impurities that is suspended in water in order to produce the treatment composition according to the invention.

 The metallo-proteins obtained if one implements in the process aimed above, a solution of zinc chloride in concentrated hydrochloric acid contain zinc.

However, it should be noted that the metallo-proteins used in the invention may contain active metals other than zinc, in particular calcium, iron or sodium, without this being the case for enzymes. obtained by a loss of catalytic activity.

 The treatment composition in the form of an aqueous solution can be applied by any appropriate means to the facades or external walls of buildings, for example by brush or by spraying. The composition according to the invention is applied to the wall to be protected, that is to say that the wall is brushed with the treatment composition until the wall is completely soaked in solution and there is no It is therefore no longer possible to make the solution penetrate further inside the wall. Such whitewashing permeates the wall to be protected over a variable thickness depending on the construction materials and which is, as a general rule, between 1 mm and 2 cm. In general, such whitewashing is carried out by using 0.2 to 0.5 kg of compound ~ ton per m2 of surface to be treated. If the treatment composition according to the invention is applied to building materials containing limestone, the metalloproteins, which have penetrated inside the material thanks to the brushing, activate the dissociation of the bicarbonates dissolved by the water infiltration and in the presence of carbon dioxide contained in the ambient air, they promote the crystallization of calcium carbonate in the form of aragonite. This creates on the surface of the treated building material, an amount of aragonite which is a function of the amount of bicarbonate dissolved and therefore, the amount of water received by the material. In other terns, the more Stone degradation conditions are important, the greater the quantity of aragonite crystallized under the catalytic action of metalloproteins, which allows it to be protected effectively. In addition, the aragonite formed on the surface is white in color and therefore has the effect of making the blackish substances fixed over time disappear on the facades of buildings so that a simple basting of a facade with the treatment composition according to the invention allows to exercise on the latter a cleaning action, without scraping the stone and therefore without wear of the latter.

Of course, the basting of the external walls with the treatment composition according to the invention can be combined with a cleaning operation of the conventional type In this case, it is observed that the use of the composition according to the invention promotes the reconstitution of the " cullet "destroyed by the restoration the spite of calcium carbonate being mainly oriented in the form of aragonite.

 The use of the composition according to the invention is also recommended on new buildings with a view to immediately protecting them and delaying their aging. In this case, the frequency of cuts may be considerably reduced.

 The composition according to the invention is not limited to the treatment of building materials containing limestone such as for example cut stones, plaster of which, irais can also be used on building materials of a porous nature containing not limestone.

In this case, the calcium bicarbonate which is not contained in the stone may be provided by the treatment composition itself. It is preferred that the content of bicarbonate of cal or m of the composition is between 05 and 5% and better still between 2 and 3%.

 The metalloprotein content of the composition according to the invention is advantageously between 0.001% and 0.02 ffi and is preferably about 0.008 X. These percentages being expressed by weight relative to the total weight of the composition.

If the metalloproteins are used in an amount lower than the lower value of the range indicated above, then they can no longer properly fulfill their catalytic activity; if, on the other hand, they are used in an amount greater than the greater value of the above-mentioned range, they will certainly exert the desired catalytic activity but the increase in the amount of metalloproteins in the composition will not result in an improvement of the result obtained.

 In the treatment composition according to the invention, the presence of the retention agent is essential: in fact, in its absence, the metalloproteins could not be maintained inside the surface layer of the materials, exposed to bad weather, and the infiltration water would entrain the metalloproteins outside of the treated materials, so that such a treatment could at most have only a limited action in time. The retention agent according to the invention is hydrophobic in nature. It is polymerizable in air and at ordinary temperature so that it can penetrate inside the pores of the stone and then polymerize insitu.In addition, it is necessary that once the polymerization is complete, the retention agent forms a protection permeable to air and, in particular, to carbon dioxide involved in the reaction catalyzed by metalloproteins. The retention agent defined above can be a silane which, by in-situ polymerization, gives a polysiloxane.

 It is preferred to use, as insitu polymerizable silane, "potassium mdthyl-siliconate" sold by the company known as "RHONE POULENC". The content of retention agent in the composition according to the invention is advantageously between 5 and 50% and is preferably 10% (these percentages being expressed by weight relative to the total weight of the composition).

If "potassium methyl methylate" is used as the polymerizable retention agent, there is added to the composition according to the invention, a catalyst for the polymerization of this compound, in catalytic amounts of the order of 2 % by weight relative to the total weight of the composition. The polymerization catalyst used is advantageously the product sold under the designation "NORAMIUM M2SH" (Quaternary ammonium salts) sold by the company known as "PIERREFITTE-
AUBY ". The above-mentioned catalyst also has bactericidal and fungicidal properties and constitutes an emulsifier.

 The treatment composition according to the invention is intended to be applied to the exterior walls of a building and it is therefore subject to ambient climatic conditions. To prevent the metalloproteins contained in the composition from degrading and can no longer exert their catalytic activity under the effect of heat from a temperature above 400 ° C., the treatment composition according to the invention contains advantageously care a phenol and, preferably, a phenol containing methyl. Among the methyl-surviving phenols which can be used in the present invention.

we can cite meta-cresol, para-crdsol. It is observed that the phenols substituted with nSthyle have better heat resistance than the phenols without methyl substituent. The phenol content of the treatment composition according to the invention is preferably between 0.001% and 0.01-, by weight relative to the total weight of the composition.

 Similarly, so that the metalloproteins of the treatment composition according to the invention can exert their catalytic activity even at low temperatures and to also lower the freezing point of the composition, it is preferable to incorporate therein a compatible antifreeze agent. with the polymerizable retention agent and having a stabilizing action on the composition. As antifreeze agent which can be used in the treatment composition according to the invention, mention may be made in particular of isopropanol, propanol-2, dimdthyl-earbitol. The content of antifreeze agent in the treatment composition is between 0.25 and 2% and is preferably about 0.75 s (by weight relative to the total weight of the composition).

 The present invention also has for its object a method of treatment for protection purposes, of the exterior walls of a building and in particular of walls made of materials containing limestone, characterized in that the exterior walls of the building are coated with protect by the treatment composition defined above, - said composition being applied to the external walls by any appropriate means, such as spraying or application by brush for example, and being used at a rate of 0.2 at 0.5 kg per m of surface to be treated.

 To better understand the object of the present invention, two embodiments of the composition according to the invention will be described below, by way of purely illustrative and nonlimiting examples.

Example 1 1st step: PREPARATION OF METALLO-PROTEINS OF THE COMPOSITION
Take 1 kg of sheep wool which is treated with approximately 3-kg of an impregnation solution composed of a mixture of approximately 70% ethanol and approximately 30% glycerine; the whole is mixed for 5 minutes, until a pasty mixture is obtained.

 The pasty mixture is divided into two equal parts (A) and (B). Part (A) is dissolved in concentrated hydrochloric acid, saturated with zinc chloride, at a pH close to 1.

 Part (B) is dissolved in a concentrated sodium hydroxide solution at a pH of about 13; the concentrated sodium hydroxide solution is obtained by dissolving sodium hydroxide tablets in water.

2eme etape PREPARATION DE LA COMPOSITION DE TRAITEMENT
On prépare la composition suivante (pour 1 kg de com- position) - Poudre à base de métIlo-protéines
obtenue dans la 1ère étape............,. 0,008 g - "Méthyl-siliconate de potassium"
vendu par la société "RHONE-POULENC"
(agent de rétention polymérisable)............ 100 g - Phénol (C6H5OH) . 0,01 g - "Noramium M2SH" (Sels d'ammonium quaternaire)
vendu par la société "PIERREFITTE-AUBY"....... 20 g - Isopropanol................................. 7,5 g - Eau ............. q.s.p..................... 1000 g ExemDle 2
On utilise la poudre à base de métallo-protéines obtenues à la première étape de l'exemple 1 : on prépare la composition de traitement suivante - Poudre à base de métallo-protéines............ 0,015 g - nXéthyl-siliconate de potassium"
vendu par la société "RHONE-POULENC"
(agent de rétention polymérisable)............ 200 g - p-Crésol.................................... 0,02 g - "Noramium K2SH" (Sels d'ammonium quaternaire)
vendu par la société "PIERREFITTE-AUBY"....... e 15 g - Isopropanol ....................................7,5 g - au .... q.s.p...................................1000 g
Les deux compositions de traitement ci-dessus spécifiées 9ont destinées à être appliquées "d refus", par exemple, à la brosse sur des matériaux de construction tels que des pierres de taille en calcaire, des enduits ou des agglomérés de ciment par exemple.The two parts (A) and (B) are mixed and the mixture is left to stand for 24 hours. The pH of the mixture is approximately 8.6. The precipitate formed is filtered under vacuum in a beaker; a crust is obtained which is washed with water and then allowed to dry; rinsed with ether and reduced to powder; 10 g of powder are obtained containing metalloproteins whose active metal is zinc. The metalloproteins thus obtained have a molecular weight of approximately 87,000; their isoelectric point is substantially zero; we observe that they have the property of catalyzing the reaction

2nd step PREPARATION OF THE TREATMENT COMPOSITION
The following composition is prepared (for 1 kg of composition) - Powder based on metLo-proteins
obtained in the 1st stage ............,. 0.008 g - "Potassium methyl siliconate"
sold by the company "RHONE-POULENC"
(polymerizable retention agent) ............ 100 g - Phenol (C6H5OH). 0.01 g - "Noramium M2SH" (Quaternary ammonium salts)
sold by the company "PIERREFITTE-AUBY" ....... 20 g - Isopropanol .............................. ... 7.5 g - Water ............. qs .................... 1000 g Example 2
The powder based on metallo-proteins obtained in the first step of Example 1 is used: the following treatment composition is prepared - Powder based on metallo-proteins ............ 0.015 g - potassium nXethyl-siliconate "
sold by the company "RHONE-POULENC"
(polymerizable retention agent) ............ 200 g - p-Cresol .......................... .......... 0.02 g - "Noramium K2SH" (Quaternary ammonium salts)
sold by the company "PIERREFITTE-AUBY" ....... e 15 g - Isopropanol ............................. ....... 7.5 g - au .... qsp ................................ .000 g
The two treatment compositions specified above 9are intended to be applied "refusal", for example, by brush on building materials such as limestone cut stones, plasters or cement agglomerates for example.

 It is observed that the use of said treatment compositions on a facade which has just undergone a facelift operation makes it possible to quickly reconstitute a spite of calcium carbonate oriented mainly in the form of aragonite. It is also observed that the coating of the facades of new buildings with the treatment composition according to the invention gives them better resistance to erosion due to atmospheric agents s the facades degrade less rapidly and the facelift operations can between, if not deleted, at least considerably spaced from facades of the same type which would not have been treated.

 It is understood that the embodiments described above are in no way limiting and may give rise to any desirable modifications, without thereby departing from the scope of the invention.

Claims (12)

Claims  1 - Treatment composition intended to be applied to the exterior walls of a building and in particular to walls made of materials containing limestone, characterized in that it contains, in aqueous solution, metallo-proteins with enzymatic activity, of which the constituent amino acids are derived from scleroproteins, in particular keratin, said metalloproteins having a substantially zero isoelectric point and having the property of catalyzing the following reaction

 the composition containing, in addition to the aforementioned metalloproteins a retention agent polymerizable in air and at ordinary temperature, and intended to maintain the metalloproteins of the composition in the surface layer of the wall of the building where they are made enter.  2 - Composition according to claim 1, characterized in that the metalloproteins are obtained in the first place, by bringing keratin fibers, preferably raw wool fibers, into contact with an impregnation solution intended to prevent lysis of the sulfur-containing amino acids forming part of the keratin fibers, the keratin fibers thus impregnated being divided into two substantially equal parts (A) and (B); secondly, by dissolving part (A) in a solution of at least one easily oxidizable metal chloride, in concentrated hydrochloric acid thirdly, by dissolving part (B) in a concentrated base solution in particular of concentrated sodium hydroxide whose pH is close to or greater than 13, and, fourthly, by mixing the two parts (A) and (B)> so as to obtain a precipitate containing the desired metalloproteins.  3 - Composition according to one of claims 1 or 2, characterized in that its metalloprotein content is between 0.001% and 0.020 4% and is preferably about 0.008% these percentages being expressed by weight relative to the total weight of the composition.  4 - Composition according to one of claims 1 to 3, characterized in that the retention agent is a silane, which by in-situ polymerization, gives a polysiloxane.  5 - Composition according to claim 4, characterized in that the content of polymerizable retention agent is between 5 and 50% and being, preferably, about 10%, the above percentages being expressed by weight relative to the weight total of the composition.  6 - Composition according to claim 4, characterized in that it contains a catalyst of the polymerizable retention agent, this catalyst being incorporated in catalyzing quantities in the composition.  7 - Composition according to one of claims 1 to 6. characterized in that it contains calcium bicarbonate in an amount between 0.5 and 5% by weight relative to the total weight of the composition.  8 - Composition according to one of claims 1 to 7, characterized in that it contains at least one phenol used in an amount between 0.001% and 0.01, these percentages being expressed by weight relative to the total weight of the composition.  9 - Composition according to claim 8. characterized in that the phenol used comprises at least one methyl substituent.  10 - Composition according to one of claims 1 to 9, characterized in that it contains at least one antifreeze agent in an amount between 0.25 and 2 ffi and, preferably, about 0.75%, these percentages being expressed by weight relative to the total weight of the composition.  11 - Composition according to claim 10> characterized in that the antifreeze agent is taken from the group formed by isopropanol, propanol-2 and dimdthyl-carbitol.  12 - Method of treatment, for protection purposes, of the external walls of a building and in particular of walls made up of materials containing limestone, characterized in that the external walls of the building to be protected are coated, by means of the composition according to one of claims 1 to 11> said composition being applied to the external walls by any appropriate means and being used at a rate of 0.2 to 0.5 kg per m2 of surface to be treated.