PT107575A - METHOD OF FUNCTIONALIZATION OF THE SURFACE OF CALCARY STONE USING HYBRID FORMULATIONS SOL-GEL - Google Patents

Abstract

THE PRESENT REQUEST REFERS TO THE FUNCTIONALIZATION OF CALCARY STONE SEEING WATERPROOF WATERPROOF AND OBTAINING RESISTANCE TO STAINS. THE CALCARY IS A MINERAL THAT OCCURS IN THE NATURE, ESSENTIALLY ESTABLISHING BY CALCITE (CA (C03) 2), WITH THE PRESENCE OF SMALL QUANTITIES OF OTHER INORGANIC COMPOUNDS, SUCH AS SYMBOLS AND OTHER OXIDES. THIS MATERIAL IS FREQUENTLY USED IN ARCHITECTURE, CONSTRUCTION, DECORATION WORKS AND DOMESTIC APPLICATIONS. AS THE MATERIAL HAS A PORSITY OF ABOUT 8-18% VOL., IT IS EASILY DEGRADED AND CONTAMINATED BY EXTERNAL FACTORS, SUCH AS ATMOSPHERIC AGENTS, HUMIDITY, SMOKING DOMESTIC PRODUCTS, COLONIZATION BY BIOLOGICAL ORGANISMS, ETC. THE DEGRADATION OF CALCARY MATERIAL REQUIRES THE APPLICATION OF MEASURES THAT PRESERV THE ORIGINAL ASPECT OF THE MATERIAL. IT MAY BE MADE BY USING SURFACE-BASED CONSOLIDATION SOLUTIONS BASED ON METAL ALCOHOLS, THE MAIN COMPONENTS OF SOL-GEL SYSTEMS. The process includes sol-gel systems with at least one component having a hydrophobic functionality, preferably from the group of silicones modified by phenyl groups and metallocene compounds, and auxiliary components of the sol-gel compounds, such as organo-synthetic compounds. APPLICATION OF THE SUN-GEL CAN BE MADE BY USING DIFFERENT METHODS, SUCH AS: WITH BRUSH OR ROLLER, IMMERSION, SPRAYING, ROTATION DEPOSITION, IRRIGATION CURTAIN OR FOR ANY OF THESE METHODS ASSISTED WITH VACUUM. AN IMPORTANT POINT IN THE DRYING PROCESS OF POROUS MATERIALS IMPREGNATED WITH SOL-GEL IS THE PRELIMINARY DRYING, WHICH FACILITATES THE EVAPORATION OF VOLATILE SOLVENTS FROM THE MATRIX AND PROMOTES A PRELIMINARY CURE AT MODERATE TEMPERATURES. THESE MEASURES ARE NECESSARY TO PREVENT EXCESSIVE THERMAL SHOCK AND BUBBLES FORMATION. THE NEW SOL-GEL FORMULATIONS HERE PROPOSALS EFFECTIVELY CONSOLIDATE THE POROSA STRUCTURE OF CALCARY STONE AND SEAL THE PORTS EXISTING IN UNREALED CALCARY MATERIAL. THE SUCCESSFUL SEALING OF THE PORES IS PROVEN BY MEANS OF WATER ABSORPTION TESTS SHOWING

Description

DESCRIPTION OF THE INVENTION The method of functionalizing the limestone surface using hybrid sol-gel formulations

Technical domain

This application describes new formulations and method of its use for the protection of limestone against water penetration. and permanent stains on architectural elements of interior and exterior, such as facades, street furniture, walls, floors, kitchens and bathrooms, among others.

SUMMARY OF THE INVENTION The present application relates to novel formulations of organic-inorganic sol-gel hybrids for the protection of limestone and the methods of their use, which comprise:

Preferably, the composition comprises at least one hydrophobic functional component, preferably from the modified phenyl or modified alkanoyl silanes or other hydrophobic sol-gel compounds; - Components: auxiliaries of sol-gel formulations which can:

Include compounds ................. me tal - organic .................. and organometallic compounds; - Processes of sol-gel synthesis; - Processes: application of sol-gel; - Stone healing cities impregnated with sol-gel.

State of the art Limestone is widely used in architectural applications such as sculptures, facades and domestic uses, among many others. In spite of their common use, there are still many problems with weather, temperature fluctuations, air pollution and organism proliferation. The main reason is the high level of porosity and the relatively low chemical stability of these materials when compared with other ornamental rocks, high humidity and aggressive chemical agents will result in. reduction of glare and the appearance of stains, for example due to the infiltration of fats, oils, vinegar, acid juices and other liquids, when these stones are used in kitchens or bathrooms.

In recent decades there has been an increase in interest: in the conservation of cultural heritage with: bane in limestone buildings [1]. The protection of these materials is based on coatings applied locally and has three main objectives; i) protect Intacta stone; ii) consolidate and preserve degraded areas; and ii) slow down the aging process,

The most successful procedures are those capable of reducing the rate of stone degradation by leaving it with the original appearance. The most important characteristics of stone consolidation products are their ability to penetrate into the open porosity The depth and penetration depends on the porosity and structure of the stone, but also on the properties of the liquid media used for the treatment, ie viscosity and super tension! icial. Also, hydro, f.ob.bi., agents are also used in conjunction with consolidating agents to further reduce water penetration by increasing the contact angle. It should be noted that for stone products exposed to the elements the reduction of the water absorption is a critical parameter of the water vapor flow rate should not be affected, so as to allow the moisture existing inside the evaporate [2,3]. The building materials porous materials, such as limestone, are traditionally protected with hydrophobic materials, such as oils, waxes, animal fats and natural resins, the desirability and availability of synthetic polymers : such as acrylic or silicone resins, their low price and ease of application, allowed a wide dissemination of these alternative products.

The patents UR-1186: 111 [4] and US, M77244 [S] were two of the first patents (requested in 1967-1968) to address mechanical and chemical resistance to pollution and weathering on the basis of precipitation of salts to improve hardness and durability of natural and artificial stones. This method consists of. immersion of the stone, or repetitive spraying to keep it moist, with aqueous solutions containing glycerine and soluble salts of barium and strontium, alkali metal fluorides, sulfates, phosphates and hydroxides. With this method, assisted by a catalyst of urea or parabolic acid, among others, the recrystallization takes place inside the stone, protecting its entire volume. This method allows a. application of hydrophilic agents and hydrophobic agents which are kept within the stone, and can be actively increased the resistance to the appearance of scale in the treated works, the method has been known for the purpose of first pieces cultural heritage exposed to the elements or deteriorated over the centuries.

In a later patent 16] (1.9'7.75), a new object is proposed for the protection of porous inorganic materials against the harmful effects of salt water, erosion, graffiti, air pollution, etc. This protection system , which is permeable to steam and gas, consists of an aqueous solution or dispersion of a carboxylated hydrophilic acrylic polymer, a curing agent and an OV radiation absorption agent. Application techniques include pyrex in a single operation.

Later (1978), another patent describing a process for rendering the hydrophobic and oleophobic surfaces was the first in which the organosilicon compounds are mentioned [7]. The object of this invention was to make the porous surfaces hydrophobic and oleophobic by applying a mixed composition of a solution containing an organic fluorine-containing polymer or a water-soluble polymer of an unsaturated carboxylic acid and of a solution of an organo compound. The fluorine-containing polymer is polytrifluorochlorethylene and the organosilicon is potassium methylsiloxane. This solution can be applied to the surface by any known technique suitable for surface treatment of any solid material with a solution or dispersion, for example by puivering, roller coating, brushing or by dipping: This: system was designed generically for the surface of the bricks or tiles of any inorganic material containing open pores and which needs curing at temperatures up to 250 ° C.

Later on (1990), organic compounds were also the basis of another patent. [8] Its authors have designed a mixed formulation of organic compounds to protect products of stone, marble, bricks, concrete and plaster atmospheric and pollutant agents and also as a process for preventing degradation caused by graffiti and the like, & The mixture is constituted by one. a perfluoropolyether having functional groups: and / or a perfluoropolyether having functional groups in the presence of a functional perfluoropolyether. These inventors: characterized the effectiveness of their solution using water absorption and vapor permeability tests, and the ease of cleaning the surfaces using cloths of One of the inventors of the patent will take another (1: 3.91) with the same objectives, using the same organic chemicals, based on aqueous microemulsions of; functional or non-functional uoropolyether. In this case a process is described in detail which confers better protection for the same amount of chemical agent but used differently 1'9 ...

Sol-gel systems based on different alkoxysilanes, in particular tetraethylsilicylate (TEOE), are among the most frequently used chemicals: for: limestone action and other materials due to their penetrability, low viscosity, weather resistance and other properties such as water vapor permeability and corrosion resistance [10-15]. These products are only polymerized during the aging within the porous structure of the stone by means of a conventional sol-gel process, cohesion of the material.

The TEOS-based consolidation products have good properties in the sol phase since the low viscosity of the monomers and alloxysilane allowed them to penetrate deeply into the porous material. After polymerization, which occurs when in contact with the ambient humidity, a stable gel is obtained with a main chain of silicon oxygen. This reaction is used to reestablish cohesion between the grains of stone affected by aging and can act as a barrier to water penetration. There are however some drawbacks due to the formation of this dense interconnection network. During aging of such formulations, cracks are formed due to the differential capillary pressure produced within the gel pores upon drying [16-IS]. The formation of cracks may know " reduced by the introduction of straight chain siioxane segments that bind to the large silicate chains of the gel [19]. Under this strategy, thin films are made therein on the surface of the macro pores which bind the components, forming bridges. Another disadvantage of dense sol-gel networks is a. reduction of. permeation of water vapor which can be quite significant for architectural stones. However, this question can be overcome when a good barrier to liquids and water vapor is required and this is applied during the stone production phase for architecture. The first time tetramethoxysilicate (TEDS) was mentioned in a patent: relative to stone protection was in 2001 [20]. In this case, methods for the protection and consolidation of calcareous materials are used, and the main example cited relates to the formation of a layer of: conversion: into the limestone mineral by a pH adjusted aqueous solution of hydroxyl carboxylic acid. In this layer, the chemical is the novel hydroxide-based functional phase thus allowing a TEOS-based reaction, with the addition of leoxy silanes and other water repellents. The validity of this approach was evaluated by flexural strength tests of different systems, from kaleite crystals to aggregates of different particles .......... .......... sizes ....................................... .................................................. .................................................. .................................................. (I.e.

Another method to preserve the original appearance of the stone has been described; in a European patent application of 2001, incorporated in 20o8, but the protection system is not of the consolidation type and is intended to use colorless coatings from titanium dioxide base-based preparations with other para-oxides the iofococatalytic degradation of pollutants;

Over the past few years real. A number of successful experiments were carried out on crack-free reflections using particles and the oxidation of oxides inserted into the gel sol. [22--24]. These nanoparticles decrease the likelihood of cracking, but have the adverse effect of increasing the viscosity of the colloidal solution and thus of the decrease of its penetration capacity in the porous stone. The use of organic solvents partially alleviates this problem but may also contribute to reducing the concentration of the consolidating products in the porous structure and hence, worse cohesion between the stone particles.

Two more recent patents from the same screening group [25--26] were intended primarily to overcome the. The formation associated with the formation of a dense network of silica within the damaged porous stone. The inventors have developed a sun-gol composition based on TEDS: which allows the. formation of a mesoporous structure. in. interconnected pores of uniform size and topology similar to that of the substrate materials. This avoids high capillary pressure in the internal silica network during. evaporation of the solvent. The size of the pores of the stone mill may be important for the properties of the reinforced materials. For example, gels deposited in biosciences with small radius pores behave as thin films without contraction induced fissure induced drying. On the contrary, after the deposition of polymers in limestones with larger pores, the formed gels frasured with the contraction in the drying: and the mechanical resistance decreased [27]. The Hatexiais for consolidation with fluorinated polymers, without cracks, were also studied for the preservation of limestone [28-31]. The results showed, as expected, a good ability to protect these coatings from water penetration due to the presence of fluorinated groups that add hydrophobic characteristics and increase dirtiness to coatings [16,32]. The addition of different surfactants to sol-gel systems increases the pore size of the gel network and increases its uniformity. This reduces the fissuration of the consolidated sol-gel and provides an effective alternative for the consolidation of the stone [11,33]. In addition to the systems: sol-gel, different acrylic or epoxy resins can be used for stone conservation. Such resins substantially increase the mechanical strength, even by impregnating only one outer layer because of its high viscosity [34],

As mentioned above, the disadvantage of the use of alkoxysilanes for the treatment of limestone is the poor chemical bonding of the hydroxysilane to calcite, the tendency for cracking due to shrinkage on drying. By drying at higher temperatures for a faster cure, limestone and marbles consolidated with syllanes can be damaged by the initiation of cracks in the; Grain boundaries that lead to intergranular trai s can cause expansion to lead to irreversible damage; for the mechanical properties: of the stone, The classic sol - gel approach involving the addition of acid para catalysis of the hydrolysis and condensation give sioxa network can also have a: negative effect: on the limestone properties. The residual acid hydrolysis can be reacted with the solid carbonates with a. formation of Ca salts. Mg, Following the. evaporation of water. or temperature changes may form. hydrated crystals with crystal pressures higher than the strength of the material. The pressure exerted on the walls of the pores can also lead to the destruction of material [35].

However, even with the known advantages, the 1-year-based products are still the best option for the consolidation of carbonated stones. The development of prot. is a part of a complex process involving a large number of variables [36,37]. Proper application of different systems involves the knowledge of the chemical nature of the solution, type of limestone, stone and ambient humidity, the location of the product (in the production site) and the ideal protocol for each of these combinations.

By combining two of the consolidation approaches above, the first patent [38] is only included in the treatment of natural stone surfaces, and the stone is impregnated with a solution of sodium hydroxide, sodium potassium or potassium silicate. TEOS is also applied on the wet surface of the stone. The patent includes the description of the various stages and the steps of application for the practical application of this technology of industrial processing of porous stone slabs. This strategy for improving the performance of the stone increases in the art to have hydrophobic, thus allowing your surroundings like kitchens - & solution and method were tested on Italian natural stone products. This patent aims to reduce the absorption of water and consequent discoloration of stone slabs. This is in part similar to some of the objects of the present invention. However, it uses different principles: chemicals to achieve part of the same results ie resistance to water absorption, and does not have as purpose anti-stain properties, as proposed in the present invention.

The present invention relates to the functionalization of limestone for the purpose of achieving resistance to staining and waterproofing. <3 limestone # A mineral occurring in nature, consisting essentially of calcite (Ca (COs) 2), with the presence of small amounts of other inorganic compounds, such as SiO2 and other oxides. fregnentemenfee used in architecture,: construction, decoration works and in domestic applications. As the material has a porosity of about 8-18 vol%. , is easily degraded and contaminated by external factors, such as atmospheric agents, moisture, domestic staining products, kinization by biological organisms, etc. The degradation of the limestone material requires the application of measures that preserve the original appearance of the material. Such can be done using surface consolidation solutions based on metal alkoxides, the major components of the sol-gel systems.

Sol-gel processes have been used in different applications in the preparation of homogeneous powders, glasses, xerogels, membranes, coatings, ceramic composites, fibers, among others, the sol-gel method. allows to combine silicon and / or other metal precursors to produce oxides modified with organic or inorganic materials, allowing to obtain specific properties. The sol-gel method. involves the evolution of the precursors in solution to an ooloidal system isol) and from this to a highly branched system called gel. The sols are dispersions of colloidal particles, with diametrals of 1 · 1000 nm in a liquid. The gel is a rigid interconnected network with pores of snbmicrometric dimensions and polymeric chains whose average length is greater than one micrometre. The precursors for the sol-gel process may be of different metals and / or silicon (Ti, Zr, Ce, Al, Si, etc.) in the form of oxides of the general formula (A) wherein A is a metal or an atom of Si, OR an alkoxy group and R is typically an alkyl linker. The common reaction of alkoxides in contact with water is hydrolysis

, 1 (OR) t H, O &gt; The hydroxyl ion binds to the A atom by providing the alcohol, the precursor being partially hydrolyzed. Subsequently, two partially hydrolyzed precursors may be bound in condensation reactions: (RO). (OH) -OH-AiOR), &gt; (RO) .alpha.

1 RO-A-OR-HO-AiOR). &gt; (RO). A-O A (OR) -. ROH <3>

The reactions f.2J and (3) can: continue to construct the network: branched with bridges ~ QAO ~ by the polymerization process to the point of gelation, in which a solid continuous network is formed: which includes the liquid phase in your pores. The rate of the hydrolysis reaction is generally higher than the rate of the condensation process. The reattachability of the silicon and the metal alkoxides is different and increases in the order: Si (GE) r <Ti (OR) to <Zr (ORI <C & E) 4. Cattle which are silicon alkoxides the reaction mixture is reacted very slowly with water, an additional catalyst is used to accelerate the process. Acetic acid, other acids, amino acids, can be used as catalysts The nature of the catalyst can affect the microstructure of the condensed products For example, compact and highly branched networks are formed from alkoxysilanes when a basic catalyst is used, On the contrary, acid catalyzed hydrolysis results in formation of randomly branched linear networks during the course of hydrolysis or condensation reactions the Si or the metal ion are formed through oxygen bridges such as Si-O · Si or M -oM, thus forming a matrix inorganic., Protection against water and moisture is one of the important characteristics of sol-gel systems. The essential role of sol-gel systems in the effective protection of lime material from these agents is due to silanes modified by organic groups. The organosilicates may have different organic fused groups such as phenyl, alkyl, fluoroalkyl, etc. The organosilicates have a general formula (RO): In this chemical formula, Y represents an organo-functional group, such as primary or secondary C 1, R 2, R 2, R 2, R 2, R 3 and R 4 are as defined above; of group Y and the value of m have: a strong influence on the water solubility of a given organosilicon monomer, organic functional groups Y may react and form an organic polymer matrix or remain inert in the matrix. certain functional groups in the sol-gel process impart hydrophobic properties to the liquid sol-gel material.

Brief Description of the Drawings Figure 1 schematically illustrates the sol-gel synthesis process using different precursors, their application and cure. Figure 2 shows electron photomicrographs scanning calcareous material after modification with different sol-gel formulations and a penile profile of the protective product on the stone. SEM of coated limestone, by Formulation 1 (the lower region &quot; corresponds to a dense coat and superior to the porous stone). (h) Depth of penetration of Formulation 2 into the skin after 5 hours of immersion. (c) Photomicrography SEM of high axapliation of the inter face between the left spin coating of the image) and; the consolidated stone (right lai) after application of Formulation 2 Figure 3 shows absorption of water in the limestone prior to sol-gel impregnation as a function of the immersion time. Figure 4 shows examples of different water absorption evolution profiles with the immersion time for the treated stones with Formulations 1 and 2, applied during different times, by immersion or roll application, and for a treated part, to which the outer layer was removed with abrasive paper. Figure 5 shows photographs of the contact angle of the water on the surface of the limestone: (a) untreated limestone (b) limestone treated by Formulation 1; and limestone treated by Formulation 3; and (d) limestone treated by Formulation 3. The contact angle values are respectively 32%, 116%, 115% and 105%. The significant increase of the contact angle in the case of treated surfaces indicates the hydrophobic character of the coatings. A. Figure 6 shows a set of photographs that reveal: the anti-stain properties of the. Formulation 1, Treats coffee stains after 24 h on (a) untreated limestone and (b) calcareous stone treated by Formulation 1 and after the procedure of I prevails, (c) and (a) repeats. (C) corresponds to: a titration of 1 (final test attempt with a strong solvent) and in (d) the classification as obtained with hot water)

Detailed description of a preferred embodiment

In the present invention, the sol-gel systems should include at least one component and with hydrophilic functionality preferentially from silane, Examples of the compounds of the invention are those of the general formula: ## STR14 ## wherein R 1, R 2, R 3 and R 4 are as defined in formula (I). (3,3,3-trifuroxopropyl) -trimatoxysilane, (3,3,3,4-trifluoropropyl) -thiomethyl oxychloride (3.3 , Etc.) or other chemicals which provide hydrophobic functionality, such as: (triphenylsilyl) isocyanate, hydroxymethyl ester, and the like, (3-methoxyphenyl) methylamine, triethylamine, triethylamine, triethylamine, triethylamine, triethylamine, triethylamine, triethylamine, triethylamine, All rights reserved.

The auxiliary components of the sol-gel formulations may include organometallic compounds and organometallic compounds, (Al, Ce, Zn, Ti, etc.) based metal oxides: they may be used as do- inorganic matter, producing the. M-Q-M network where M is Si or the metal. The metal-organic compounds may be stabilized by organic agents such as acetylacetone, ethoxy acetoacetate, acetic acid and the like. The organometallic compounds may be selected from the group of tetrasodiolate, zirconium (IV) propionate, txtanxis (T) isopropoxide, zirconium hexafluoride (iV), titanium (IV), aluminum sulfate, aluminum tert-butyl peroxide, aluminum oxide, aluminum oxide, cerium oxide (IV), and cerium oxide (IV) Silanes can be used as inorganic and organic network forms. The inorganic network is formed through the bonding of Si atoms with oxygen forming O-Si bonds. The organic re be formed by the organo-functional silanes having at least one functionally reactive functional group, such as epoxy, ketone, vinyl, myoxy, isocyanate, etc. At least one auxiliary component should be used in the synthesis of sol --gel,

Route of synthesis is 1-gel; I was going to typical of sol-gel synthesis is shown in Figure 1 for a hybrid sol-gel system containing different functionalities. &amp; synthesis includes mixing in reactor 1 either the silane mixture or metal alloxides, in combination with a complexing agent, followed by the addition of water. (solutions of nitric acid, G3, M3, or M4 have been used primarily for the hydrolysis of the mercaptan precursors and silanes). The reactor 2 is filled with different silanes with or without the presence of solvent. The hydrolysis reaction is carried out by a solution of acid, as in the previous case. Then the two solutions are isolated in the reactor 3 and the aging of the resulting solution is carried out, which may have different durations. Thereafter, the sol-gel product is applied to the porous substrates and oven-cured. This preparation of the sol-gel route provides a typical synthesis process, in some cases sol-gel systems. may contain additional components and different precursors.

Process of sol - gel application: a. application of the sun-gel can be done by using different methods such as brushing or rolling, immersion, spraying, rotational deposition, irrigation curtain or by any of these vacuum-assisted methods. Immersion is a relatively easy method of application, although has a high associated cost since it needs to use a large volume of product; a complete immersion of the material is carried out in the sol-gel, in order to coat the inner and outer surfaces. The application with a pincer or roller is by soaking in the sol-gel and applying forward and backward movement throughout. surface of the stone, so as to distribute the sol-gel on the axiom. surface. Application by spray, the sol-gel is placed in an enclosed container and transferred to. However, with this method of application there may be high costs associated with the loss of product due to excessive spraying, the method of applying the soldering agent to the surface of the spray gun. Airless high-pressure spraying will allow for less loss of product relatively to the conventional spray technique, depending on the possible methods of: application of the sol-gel. Immersion and use of a brush or roller are preferable since they offer a better penetration of the sol - gel in the porous network of the limestone -

Curing cycle: One of the important points in drying porous materials impregnated with sol-gel. and the. drying which facilitates evaporation of the matrix solvents and provides a prior cure at moderate temperatures. These measures are necessary to avoid boiling of the solvent or the thermal shock. The sol-gel curing procedure is described below. After application of the sol-gel the infiltrated pieces are dried for about 1-2 h and then transferred to a preheated oven at 60 ° C maintained at this temperature for 10 min. The oven temperature is then changed to 120 ° C and the parts are grounded for 20 min on the temperature ramp to 120 ° C and was followed for 80 min at the plate at 120 ° C,

Fina.lme.nte, ...... as ..... parts are taken out of the greenhouse. However the healing process. can be changed according to the requirements and existing equipment. For example, the maximum polymerization temperature may vary according to the thermal stability of the limestone.

Examples of formulations

The synthesis and characterization of three sol-gel formulations based on different meta components are presented below. 1 and / or hybrids.

Example 1: Formulation 1 based on siland / metal organic hybrid *

Ko jsritfteir®: example :, a sol-gel based on the combination of a metal-organic compound and silanol was used for the consolidation of limestone. The synthesis includes a mixture in reactor 1 of a 20.85 mM solution. of tetrahydrofuran (2 H) (TFOE) was treated with 11.75 ml of ethylacetoacetate for 2 hours. of a 0.13 M HNO solution. were added to initiate the hydrolysis which lasted for 1 hour. Reactor 2 contained a mixture of 22.35 ml of 3-glycidoxypropyltrimethoxysilane (GPTMS), 22.7 ml of phenylmethylsilane (PTMS) and 5 ml of hexadecyldimethoxysilane in 12.75 ml of aqueous solution of After completion of the hydrolysis, the two solutions were mixed in reactor 3 for 1 hour. After completion of this phase of the reaction, the reaction mixture was allowed to cool to room temperature. the sol-gel was subjected to flash envexa during the period from 1 to 48 h before application to the limestone. The application of sol-gel to limestone substrates can be done using different methods, The present example of sol-gel was applied by immersion during different immersion times 1.5, 1, 2, 3, 4, 5, and 6, respectively. 5 min The sol gel was applied after 1 h or 1 day of stirring at room temperature. The sol-gel treated pieces were dried for X h at room temperature, followed by curing at 60øC for 10 min and 120øC for 80 min.

Example 2: Formulation 2 based on silanes

In the second example, a sol-gel based on the combination of different silanes and additives was used for the consolidation of limestone. The synthesis is carried out in reactor 1 of a solution of 17 ml of methyltrimethoxysilane (MTEOS) with 2.9 ml of 3-methacethoxymethylpropylphosphinylsiloxysilane MMAPTS3 and 5.5 ml of 0.1 M aqueous NHCh solution to initiate the hydrolysis . The solution was stirred for 1 h. The reaction mixture was cooled to 0 ° C and stirred for 2 hours. . 1-yr (PTMS) and 8 ml methanecarboxylic acid (methoxysilane) and 5 ml of hexane trimethoxysilane. -1 6 ml of aqueous solution. 0.1 M NHCh were added to reactor 2 to initiate the hydrolysis. Synthesis was performed at a temperature of about 22 ° C. After completion of the hydrolysis, the two solutions were run in reactor 2 for 1 hour. After this is completed. of the synthetic process: &amp; sol -001 was submitted to. during 1 to 72 hours prior to. api ization on a material. .1 fall over. O . In a similar manner to Example 1 the sol-gel was applied by immersion at different times of 1,5 and 15 min. The sol-gel was applied after 1 h after aging at room temperature. The sol-gel treated pieces were dried for 1 h at room temperature, followed by drying, at 60øC for 10 min and 120øC for 10 min.

Example 3: Solvent-Based Formulation 3 of TSOS / 1 Triisopropylsilyl) isocyanate The third example shows a sol-gel formulation based solely on triethylsilyl-isocyanates (tetraols) The synthesis was carried out by the reactor in reactor 1 of 60 ml of tetraethyl ether. ossi li. was treated with 12 ml of 0.1 M NHCh solution to initiate the hydrolysis: vigorously stirring for 30 min after which is transferred to the reactor 3. The reactor 2 contains 15 ml of triethylsilyl X 1-yl) isocyanate and 7.3 ml of tetrahydrofuran are mixed under constant stirring for 5 min. The contents of reactor 2 were added dropwise to the reactor 3 mixture under constant stirring. Reactor 3 was allowed to mix for 1 h. The sol-gel was applied to pieces of limestone by immersion. The sol-gel treated pieces were dried for 1 h at room temperature, followed by drying at 60 ° C for 10 min and 120 ° C for 80 min.

EXAMPLES OF RESULTING PROPERTIES Figure 2 shows scanning electron microscopy (SEMI images of limestone treated with Formulations 1 and 2, Figure 2 shows the formation of an impermeable coating on Formulation 1 treatment. of Form 2 the sol-gel penetrates into the interior of the stone (Figure 2b) and consolidates: the porous structure under the original surface, as shown in the photomicrographs: high magnification of Figure 2c> Elemental chemical analysis (EDS) cross-section of the coated limestone clearly shows the presence of a silicon (Si) signal which is soluble in the presence of the silica. The solubility of the sol-gel process during infiltration may be in the order of 2 mm, Figure 2b, and depends on the sol-gel formulation, the aging time of the solution and the infiltration time. Successful pore sealing was also checked by means of water absorption tests a made according to Standard NP ΕΝ 13'755 (test methods for natural stone; determination of the water absorption at atmospheric pressure, which allows to determine the absorption of water as a function of the immersion time. Figure 3 shows the water absorption profile in untreated limestone, to a maximum of about 4.5% by weight relative to the stone. The water absorption is reduced by a factor of about 10 times when compared to the untreated limestone, Figure 4, regardless of the method of application: time of immersion or deionization of the solution prior to application, Such effect is due to The strong increase in the hydrophobic character due to the consolidation effect of the solgel and the compositions used was also demonstrated by measuring the contact angle of the water. Figure 5 shows the contact angles for untreated limestone and treated with the three sol-gel formulations described above. The contact angle increases from 32 ° for the untreated stone to 116 ° for. Formulation 2, which reveals a substantial improvement in the hydrophobic properties of the surface, due to the. modification of the porous limestone structure by the sol-gel formulations.

Caraeterístleas anti. were obtained with some of the following formulations: Figure 6, which compares the behavior of the untreated stone with that of the treated stone with Pormilaçlo 1. This formulation is resistant to coffee stains, classified with 5 according to the norm NP EN ISO 10545-14 (Ceramic tiles: Part 14: Determination of stain resistance). This standard. classifies the stain resistance properties according to the method of removal: - Classification 5: removal of spots with hot water (55 .................... ° C ) ...................................... - Classification 4; stain removal with non-aggressive impervious liquid and a non-abrasive cloth. - Classification 3: Removal of stains with aggressive cleaning fluid and rotating hard bristle brush, - Classification 2: removal of stains by immersion for 24 hours in a strong solvent, - Classification 1: stain not removed. Formulation x is also classified as equal to or greater than 3 for other agents that cause stains, such as aseite, vinegar, lemon juice, wine with iodine. Untreated stone is classified as 1 for all coloring agents except iodine, rated 2.

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Aveiro., March 18, 2015

Claims (14)

Method of functionalizing limestone characterized by using hybrid sol-gel type formulations. Method of functionalizing the limestone according to claim 1, characterized in that the porosity of the surface of the stone is decreased by means of sealing with an organic-inorganic hybrid network. A method of funneling the limestone according to claim 1 characterized in that the hydrophilicity of the stone surface is enhanced. A method of funnalization of the limestone according to claim 1, characterized in that the absorption of water by the treated stone is significantly reduced. 5. Method of func tioning the limestone according to claim 1, characterized in that the strength of the stone treated with patches of products: inventories or other sources is increased significantly. 6. New limestone products characterized in that the superfine is modified by application of hybrid materials which, provide greater protection from the weather: and cue agents cause stains .; 3. New limestone products according to claim 1, characterized in that the outer layer of the treated limestone can be removed by grinding, keeping the treated stone the ability to protect from the weather and agents that cause stains ?. New limestone products according to claim 6 characterized in that the hybrid sol-gel material is applied to the surface of the stone by any of the following methods: roller brush, dipping, spraying, rotational deposition, irrigation curtain or by any of these vacuum assisted methods. New limestone products according to claims X ... 2, 34, 5 and 9, characterized in that the hybrid sol-gel material contains functional hydrogen peroxide components. New limestone products according to claim 9 characterized in that the functional hydrophobic components are based on organosilanes having at least one of the following alkyl, alkoxy, fluoroalkyl, or mercapto groups. New limestone products according to claims 9 and 10 characterized in that the sol-gel formulation has a functional hydrophilic component which may be substantially bound to the organic or inorganic sol-gel network, 12. New limestone products according to claims 9 and 10 characterized in that the sol-gel formulation has a fused cyclodex component which is reactive with the organic or inorganic sol-gel matrix. 13. New products from. limestone according to claims 9, 10, XI, 12, and wherein the sol-gel formulation is based on s. 1 years functional .................... with acri lato and a network of s I li ca. S .10; ·). New limestone stone flakes according to claims 9, 10, 11, 12, 12, 13, 13, 14, 16, 16, 16, 16, 16, 16, 16, 16, of a titanium dioxide network (TiGj) &gt; 15. New limestone products according to claims 9, 10, 11, 13, 13 characterized in that the sol-gel formulation is based on epoxy-functionalized silanes and a 2-ion dioxide network ( ârOb, New calcareous products according to claims 9, 10, 11, 12, 12 characterized in that the sol-gel formulation is based on the isocyanate functional group and a silica network. (SiOs), New limestone products according to claims 9 to 16 characterized in that the hybrid sol-gel formulation is applied to a porous stone material in which the cure is effected over a temperature range of 60 ° C to 200 ° C. Ave., March 18, 2015