Use of Biocidal Aerosol Compositions in Marine Coatings

Abstract

The present invention relates to silica aerogels having high to very high loadings of encapsulated biocidal and / or biorepellent compounds (55-90% w / w) and very low thermal conductivity, and methods for making and using such aerogels in antifouling compositions that are particularly suitable for coatings that are naturally exposed to humid conditions and / or water, including seawater, and are therefore prone to fouling (marine paints, coatings, sealants, lacquers, wood protection, or similar controlled leaching systems).

Description

Technical Field

[0001] The present invention relates to silica aerogels having encapsulated biocidal and / or biorepellent compounds in high to very high loadings (55 - 90% w / w) and very low thermal conductivity, and methods of making such aerogels and using them in antifouling compositions particularly suitable for coatings (marine paints, coatings, lacquers, wood protection) and sealants that are naturally exposed to humid conditions and / or water containing seawater, whereby fouling is likely to occur.

Background Art

[0002] Biocides and biorepellents are substances used to prevent the unwanted growth of biological organisms in the ocean surface (boats, ships, and facilities including submerged equipment, or other areas), or in areas that are likely to be affected by such unwanted growth. Biocides and biorepellents are usually added to products such as protective coatings, coatings, and lacquers that may be applied to areas susceptible to the effects of such unwanted growth, and also to elastic sealants such as silicone sealants commonly used in "wet rooms" such as kitchens, bathrooms, and toilets, which are regularly exposed to high humidity indoors.

[0003] The protective coatings applied for external or internal use usually have two basic functions: protection and decoration. Elastic seals are usually used to close joints and cracks between non-elastic surfaces such as ceramic tiles. In this case, the functions of the seal are to conceal the joints and cracks, absorb deposits on non-elastic surfaces, and prevent the intrusion of moisture. Therefore, elastic seals also have the basic functions of protection and decoration. The surface of a ship exposed to seawater presents special problems because microorganisms, plants, algae, and animals tend to deposit on it, thereby increasing the propulsion resistance of the ship, and thus the speed tends to decrease or the fuel consumption increases. This biological process is called fouling and can be broadly classified into two groups: microfouling, which includes colonies of single-celled algae and bacteria (often called "slime"), and macrofouling, which includes both fouling by plants (weeds) and fouling by animals. In particular, macrofouling causes problems related to propulsion resistance.

[0004] The propulsion resistance imposed by a large invasion of barnacles can increase the ship's fuel consumption by up to 40% (The Economist Technology Quarterly Q3 2011, Sep 3 rd 2011). Therefore, solving the general fouling problem can have positive economic and environmental impacts through reduced fuel costs and CO2 emissions. At the same time, antifouling paints always present problems due to the amount of biocidal compounds (including heavy metals) released into the sea.

[0005] Attacks by biological organisms such as fungi and algae (either in a wet state or on the surface of a coating or sealant) can impair both the protection provided by the coating film or sealant and its decorative effect. This biological process is called fouling. Molds and mildews are common fungal species that can often attack both indoor and outdoor surfaces where moisture is high. Mold spores can pose serious allergy problems, and over time, molds and other fungi can destroy wooden building materials in particular, so it is important to efficiently prevent mold and other types of fouling.

[0006] The types of fouling mentioned are generally addressed using paints, coatings, and sealants that release biocidal compounds that are active on the surface. Biocides are compounds that are toxic to microbial cells and thus prevent the growth of unwanted micro and macro organisms (i.e., foulants), while biocides that are used less frequently are usually relatively low in toxicity and act by repelling or deterring unwanted organisms from areas that would otherwise attract foulants.

[0007] Since most antifouling compounds are not effective against all types of foulants, the active compounds are used in combination. In conventional antifouling coatings and sealants, the leaching of the active compounds rarely follows the same decay curve. Therefore, a coating or sealant may only be able to prevent fouling partially before the end of its service life.

[0008] The service life is limited by various factors such as the chemical decomposition and dissipation of the biocide due to being washed away from the coating or sealant, and becomes much shorter than the life of the surface that the coating and sealant are supposed to protect. Therefore, there is great value in extending the service life of protective coatings and sealants.

[0009] The release of biocides and / or biocides from antifouling coatings and sealants can be controlled by encapsulating the active compounds, protecting them from unwanted degradation reactions, and releasing them slowly to extend their useful life in various matrices. Thus, ideally, the encapsulation method should allow for a high loading of biocides / biocides in the encapsulating material and continuously release the active compounds from the encapsulating material throughout the service life of the coating or sealant of which they are a component. This combination of functions ensures a long-term antifouling effect, maximizes the utilization of the added active compounds, thereby reducing the amount of biocides required and the amount of biocides released into the environment unnecessarily, reducing both the cost of goods (CoG) and the adverse environmental impact.

[0010] The concept of encapsulation itself has been addressed previously. For example, see Jamsa S. et al (“Slow release of a biocidal agent from polymeric microcapsules for preventing biodeterioration”, Progress in Organic Coatings, Vol 76, Issue 1, January 2013, p269-276), where the biocide / biocide is trapped within water-soluble polymers (such as polyethyleneimine (PEI)) or polyacrylate capsules). Another similar approach is that of A Kamtsikakis et al. Bioengineering 2017, 4(4), 81, “Encapsulation of Antifouling Organic Biocides in Poly(lactic acid) Nanoparticles”, which describes, among other things, the encapsulation of Irgarol 1051, Econea and zinc pyrithione (ZPT, ZnP) into biodegradable polymer particles.

[0011] These methods achieve the goal of reducing the initial leaching of biocides / biocides because the protective polymer shell must first be at least partially dissolved before the biocide / biocide can escape from being confined within the capsule, but this particular encapsulation concept does not meet the practical requirements of formulations used as components of coatings or sealants such as marine antifouling coatings. Biocide / biocide particles surrounded by a thin polymer shell are first applied during mixing into the coating or sealant composition and are then easily damaged due to the mechanical (shearing) forces applied when applying the coating or sealant to a surface such as the ocean surface (e.g., the hull of a ship or vessel, or a submerged static structure). Furthermore, the loading of biocides / biocides in the polymer capsules as described is not high enough.

[0012] In contrast to the physically weak polymer microcapsules discussed above, an inert and mechanically robust material such as silica is a better option for encapsulating active compounds dispersed within an antifouling coating or sealant composition. Silica gel has the advantage that its hydrophilic / hydrophobic properties can be modified to suit the type of product. For example, a more hydrophobic silica gel may be preferred as an additive to a solvent-based coating composition, while a hydrophilic silica gel may be preferred for an aqueous composition.

[0013] The inventors first developed a method for encapsulating a solid active compound within silica aerogel particles. This is described in International Publication No. WO 2009 / 062975 of the International Patent Application. According to the described procedure, aerogels with a content of encapsulated solid active compound of up to about 50% w / w could be achieved on a small scale. However, attempts to produce an aerogel with a content of encapsulated zinc pyrithione of about 75% w / w as the solid active compound using the same procedure, however, resulted in a product that absorbed water too readily and appeared more heterogeneous. This indicates that the method described in International Publication No. WO 2009 / 062975 was unable to provide a well-defined filled aerogel with a loading above approximately 50% w / w.

[0014] The loading limit of the solid active compound in silica aerogel is very important for their final use as an antifouling component of a coating or sealant composition. When a biocide encapsulated within silica aerogel is added to an antifouling composition, silica is also necessarily added in a ratio determined by the percentage loading of the particular aerogel. The inventors have found, as a rule of thumb, that an antifouling composition should not contain more than about 1.5% w / w of SiO2 (silica) as otherwise it will become too thick / viscous and difficult to apply uniformly. Therefore, due to the silica limit of 1.5%, an increase in the amount of biocide in an antifouling coating or sealant composition cannot be achieved simply by adding a large amount of filled aerogel to the coating composition.

[0015] For example, · An aerogel with a biocide content of 50% contains 50% silica. Thus, such an aerogel can be added at most 3% w / w of the composition to keep below the 1.5% silica limit. This means that the final composition contains 1.5% w / w of biocide. More biocide cannot be added via this route without exceeding the 1.5% silica limit. ·Since the aerogel containing 80% w / w biocide contains 20% silica, this aerogel can be added to the composition at a maximum of 7.5% w / w. The final composition prepared using this aerogel will contain 80% × 7.5% = 6% w / w biocide and still contain 1.5% or less silica. ·When using an aerogel with a biocide loading of 90%, 15% w / w of the aerogel can be added to achieve a biocide level of 13.5% w / w in the composition without exceeding the "silica limit" of 1.5%.

[0016] Figure 2 shows the biocide content (w%) in the coating composition as a function of the biocide loading in the aerogel when up to 1.5% silica may be added to the composition.

[0017] Therefore, ·The loading of the active compound is high (preferably 55% or more), ·The resulting coating or sealant incorporating the encapsulated biocide has sufficient water absorption, ·The biocide concentration on the surface of the antifouling composition is constant over its lifetime, There remains a need for improved encapsulation methods that can provide access to a wide selection of encapsulated biocides and repellents.

Brief Description of the Drawings

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[0019] Summary of the Invention The inventors of the present invention have analyzed the behavior of antifouling coatings and sealants containing biocidal and / or biorepellent active compounds encapsulated in aerogel particles under different conditions with respect to temperature and humidity over the years, and have found that the antifouling effect depends quite significantly on correctly controlling the water absorption rate of the composition. Specifically, when the water absorption rate is too low (<1.5% by weight), fouling occurs (because the biocide cannot exert its effect under overly dry conditions), whereas when the water absorption rate is too high, dissolution is too rapid and ultimately the biocide is found to be lost. Therefore, it has been found that it is important for the antifouling composition to be able to absorb enough water to maintain a saturated solution of the active compound in the surface layer of the coating or sealant composition. Water absorption rate values in the range of about 1.5 - 6% are considered optimal.

[0020] Furthermore, the inventors have found that it is necessary to control the water absorption rate of the embedded aerogel particles themselves in order to adjust the performance of the antifouling coatings and sealant compositions. The two most important influential parameters for this purpose are 1) the filling amount of the active compound into the encapsulated aerogel particles, and 2) the porosity of the aerogel particles. Also, a high content uniformity, i.e., a highly homogeneous distribution of the encapsulated biocide or biorepellent in the aerogel particles, is also important for the performance of the antifouling coatings and sealant compositions.

[0021] Accordingly, an object of the present invention is to provide silica aerogel particles containing a high to very high filling amount (55 - 95% w / w) of a biocide and / or biorepellent, which, when incorporated into an antifouling coating, provide a sufficient water absorption rate (e.g., in the range of 1.5 - 6% w / w) of the dry coating. Coatings for onshore wooden buildings can have a higher range, e.g., up to 11% w / w.

[0022] In order to achieve this objective for a wide variety of biocides and / or biocides (having various physicochemical properties including solubility in various solvents and pH tolerance), the inventors have developed a procedure for producing novel aerogel particles containing encapsulated biocides and / or biocides having the mechanical robustness and high to very high loading of active compounds required for incorporation into the final composition.

[0023] When incorporated into antifouling coatings and sealants, these novel particles provide sufficient water absorption. Thus, the particles have been found to be valuable as additives to antifouling coatings and sealants for both offshore and onshore applications.

[0024] Thus, the antifouling additives of the present invention have been found to be useful in coatings applied to offshore surfaces that are periodically or constantly submerged. Examples of constantly submerged surfaces include the hulls of boats, ships, and other vessels including both commercial tankers, pleasure boats, and yachts, but also swimming pools, rain water basins, oil drilling rigs, and fish farm buildings, which include constantly submerged building components. Examples of surfaces that are only periodically submerged include static marine structures such as the lower part of the pylons of offshore wind turbines, as well as other offshore structures, piers, and harbor buildings that are periodically submerged by high tide or wave inundation.

[0025] The antifouling additives of the present invention have also been found to be useful in coatings and sealants applied to onshore surfaces that are periodically exposed to moist air and rainfall. Such surfaces are typically found on houses and other buildings in tropical regions and areas with frequent rainfall or heavy fog. Other examples include the indoor surfaces of rooms that are periodically exposed to high humidity, such as bathrooms, showers, saunas, and indoor swimming pools. In such "humid indoor environments", a particular use of the antifouling additives of the present invention is found in sealants, for example, used to fill cracks in tiles that are often attacked by mold and mildew.

[0026] As described above, the inventors have previously worked on the encapsulation of zinc pyrithione (ZnP) into aerogels (see, for example, WO 2009 / 062975). The new method described herein uses tetraalkoxysilane and alkyltrialkoxysilane in approximately the same ratio as in the original procedure described in WO 2009 / 062975, but the amount of water used in the gelation process is much less.

[0027] Furthermore, less ammonia is used as a catalyst, and the ammonia is gradually added to the solution of silicate in a separate ethanol solution rather than as a concentrated aqueous solution mixed with the starting materials. Additionally, acidic catalysis has been shown to be effective even in certain cases where the biocide is unstable under alkaline conditions. This research is described in WO 2020 / 002659, a co-pending application of the inventors.

[0028] The inventors have continued to develop the encapsulation procedure with the aim of enabling a wider selection of biocides and repellents that have hitherto been limited by solubility problems or incompatibility with the selected gelation catalysts. The results herein are discussed in the detailed description, but in particular, the initially formed alcogel ("wet gel") of the present invention may be dried using freeze-drying rather than supercritical carbon dioxide extraction. Freeze-drying is a much more commercially viable and scalable procedure than supercritical carbon dioxide extraction. Thus, the aerogel particles resulting from this modification of the manufacturing procedure are isolated as freeze-dried solids.

[0029] The new manufacturing procedure was first used to enable the production of aerogel particles containing highly loaded encapsulated ZnP. Subsequently, this method has proven to be able to provide aerogel particles containing highly loaded encapsulated biocides other than ZnP. This is important as contaminants are usually not sensitive to only one type of biocide, as previously discussed. This method ensures the reliable production of highly loaded (>55% w / w) aerogels.

[0030] The aerogel particles produced according to the present invention (including particles containing ZnP) have been found to have better homogeneity and different porosities than the particles produced by the procedure described in WO 2009 / 062975. This can be measured by mercury intrusion porosimetry and can be explained, for example, by the intrusion volume or bulk density of the aerogel particles (see the Examples section).

[0031] The aerogel particles produced according to the present invention have also been studied with respect to their opacity and thermal conductivity.

[0032] Thus, the filled aerogel particles of the present invention have been found to have a very low thermal conductivity (0.01 - 0.05 W / m * K) and to be better insulators than the pure biocide and / or repellent itself.

[0033] Furthermore, the filled aerogel particles of the present invention have generally been found to have an opacity as measured by their "hiding power" or coverage rate when tested according to ISO 6504-3:2019, "Determination of hiding power".

[0034] Thus, what differentiates the filled aerogels of the present invention from the prior art, including WO 2009 / 062975 and WO 2020 / 002659 of the inventors' own published applications, is a very low thermal conductivity (usually 0.01 - 0.05 W / m * K) combined with a high loading - very high loading (>55% w / w) of the achievable biocide.

[0035] Thus, in a first aspect, the present invention is an antifouling additive, wherein the antifouling additive a. an inorganic silica-containing aerogel comprising the following; b. a porous gel lattice, and c. optionally, an alkoxide containing Sc, Ti, V, Cr, Mn, Fe, Co, Y, Zr, Nb, Ru, Hf, Ta, W, Re, Al, Ge, In, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu, and d. one or more biocidal or biorepellent compounds trapped within the aerogel, comprising wherein the silica-containing aerogel contains at least 55% by weight of the one or more biocidal or biorepellent compounds, wherein the trapping of the one or more biocidal or biorepellent compounds occurs during the sol-gel formation of the gel, and the thermal conductivity of the antifouling additive is 0.01 - 0.1 W / m * K, to provide an antifouling additive.

[0036] The particles of the first aspect can be provided by a newly developed manufacturing procedure as described above, which is a further development of the methods described in PCT International Publication No. WO 2009 / 062975 and International Publication No. WO 2020 / 002659. Thus, very large amounts of biocides and / or biorepellents ("active compounds") can be encapsulated in situ in an alcogel formed by a two-step procedure using, optionally in combination with an alkyltrialkoxysilane, a tetraalkoxysilane (monomeric tetraalkyl orthosilicate or pre-condensed tetraalkyl orthosilicate or pre-condensed monomeric tetraalkyl orthosilicate) + the active compounds required in the sol-gel preparation (which are converted to and dried in the aerogel in the final step).

[0037] The resulting aerogel particles typically contain an encapsulated active compound with a content of approximately 55 - 75% w / w, but depending on the biocide used, can be produced to contain up to approximately 90 - 95% w / w. By varying the ratio of the catalyst as the starting material, various porosities, densities, and hydrophobic / hydrophilic behaviors of the final aerogel particles can be obtained. The aerogel particles can also be prepared to match both solvent-based and aqueous coatings and sealants by such variations of the method.

[0038] Accordingly, in a second aspect, the present invention further provides a method for providing the antifouling additive of the first aspect, comprising the following steps. a. Preparation of Solution 1: Mix 100 parts of tetraalkoxysilane (monomeric tetraalkyl orthosilicate or pre-condensed tetraalkyl orthosilicate or a mixture of pre-condensed and monomeric tetraalkyl orthosilicate) with 0 - 50 parts of alkyltrialkoxysilane, 350 - 500 parts of ethanol, and 200 - 450 parts of biocide, and stir vigorously with a mixer. Another lower alcohol can be used for dissolution. Alkoxides containing Sc, Ti, V, Cr, Mn, Fe, Co, Y, Zr, Nb, Ru, Hf, Ta, W, Re, Al, Ge, In, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu can optionally be added at this point. b. Preparation of Solution 2: Mix 100 parts of ethanol, approximately 50 parts of water, and 0.25 - 15 parts of a gelling catalyst. c. Slowly add Solution 2 to Solution 1 and stir vigorously for 20 - 25 minutes. Continue stirring at a low speed until signs of gelation are observed, which is approximately 15 minutes later. The resulting solution may be transferred to one or more separate containers for gelation. The gelation time is about 30 - 60 minutes. d. The gel is stored in a suitable container for 2 - 5 days and then transferred to an extractor(s). e. Cut the wet gel into smaller pieces and transfer it to a suitable pressure vessel (a flow reactor equipped with heating jackets and metal frits at both ends) under ethanol. Then, flow ethanol through the gel at a rate of 0.5 mL / min. Next, raise the temperature in the heating jacket to 37 - 40 °C and increase the pressure from 3 bar / min to 110 - 115 bar (or approximately 80 bar in the case of a biocide soluble in ethanol) over 4 - 8 hours until the ethanol recovery rate is less than 1 ml / min. The exact values of temperature and pressure depend to some extent on the selected packed aerogel and can be easily evaluated by routine experiments. CO2 is flowed into the vessel at a rate of approximately 6 mL / min measured at 10 °C. After flowing, release the pressure slowly over 0.5 - several hours.

[0039] In the case of the above steps a - e, ethanol can be easily replaced by another C1 - C4 alcohol such as tert - butanol. Further, as described above, the supercritical drying procedure can be replaced by freeze - drying.

[0040] In a third aspect, a fouling - preventing additive obtained by the method according to the second aspect is provided.

[0041] In a fourth aspect, the use of the fouling - preventing additive according to the first or third aspect in a marine coating or a coating for wood protection or a humid indoor environment is provided.

[0042] In a fifth aspect, a fouling - preventing paint or sealant composition containing the fouling - preventing additive according to the first or third aspect of the present invention is provided.

Mode for Carrying Out the Invention

[0043] Detailed Description As described in the summary of the present invention, the inventors have developed a new manufacturing procedure for the production of novel aerogel particles containing encapsulated biocides and / or biocides ( "active compounds") having the mechanical robustness and high filler content - very high filler content required for incorporation into coating and sealant compositions. These particles, when incorporated into such antifouling compositions, provide a sufficient water absorption rate of the dry coating or sealant. Therefore, said particles have been found to be valuable as additives for antifouling coating and sealant compositions.

[0044] Accordingly, in a first aspect, the present invention provides an antifouling additive, wherein the antifouling additive a. an inorganic silica-containing aerogel comprising the following; b. a porous gel lattice, and c. optionally, an alkoxide containing Sc, Ti, V, Cr, Mn, Fe, Co, Y, Zr, Nb, Ru, Hf, Ta, W, Re, Al, Ge, In, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu, and d. one or more biocidal or biostatic compounds trapped within said aerogel, comprising said silica-containing aerogel comprises at least 55% by weight of said one or more biocidal or biostatic compounds, said trapping of said one or more biocidal or biostatic compounds occurs during sol-gel formation of said gel, the thermal conductivity of said antifouling additive is 0.01 to 0.05 W / m * K, providing said antifouling additive.

[0045] In an embodiment of the first aspect, when said aerogel comprises up to 75% by weight of zinc pyrithione, the bulk density of said aerogel has a value of up to 0.5 gr / ml.

[0046] To distinguish a particular embodiment of the present invention in which the aerogel particles contain zinc pyrithione, which is produced by the method of WO 2009 / 062975 and discussed in WALLSTRОM, E. et al.: ‘‘A new concept for anti-fouling paint for Yachts’’, PROG. ORG. COAT vol. 72, 2011, pages 109 - 114, from the product referred to as ‘‘75% ZnP aerogel’’, a limitation regarding the bulk density of the ZnP-containing aerogel ( ‘‘when the aerogel contains up to 75% by weight of zinc pyrithione, the bulk density of the aerogel has a value of at most 0.5 gr / ml’’) has been introduced.

[0047] As described above, it has been found by mercury intrusion porosimetry experiments that the packed aerogel containing approximately 75% w / w of ZnP prepared from precondensed silicate has a significantly lower bulk density and a significantly higher intrusion volume than the aerogel produced from normal silicate. As can be seen in the experimental section (Example 8a), the average bulk density of the aerogel containing 75% w / w of ZnP produced from normal silicate is about 0.58 g / ml (batch 1A - C), while the bulk density in the case of the packed aerogel (batch 2A - B) similarly produced from precondensed silicate is about 0.39 g / ml (all values in the series are measured by mercury intrusion porosimetry). It has been found that the bulk density of the aerogel comparable to the ‘‘75% ZnP aerogel’’ produced by the method of WO 2009 / 062975 is 0.56 g / ml.

[0048] The average bulk density of the aerogel containing approximately 75% w / w CuP produced by the method of the present invention is also <0.50 g / ml (Example 8b, batches 3A - C, Figure 7). However, the bulk density of the filled aerogels described herein can vary significantly, particularly as a function of the actual filling and the density of the biocide itself used (see also Figure 8), and thus is not a general limiting characteristic of the novel filled aerogels. What differentiates the novel filled aerogels from the prior art is primarily or additionally and exclusively the high to very high filling amounts of achievable biocides, which, for example, in combination with a very low thermal conductivity (usually 0.01 - 0.05 W / m * K), can be verified by thermogravimetric analysis (TGA).

[0049] Since then, using the same manufacturing procedure, the inventors have produced using other biocides such as DCOIT, IPBC, trifulanide, diuron, Cu pyrithione (CuP), etc. See the Examples section.

[0050] In a preferred embodiment, the antifouling additive of the first aspect comprises aerogel particles containing at least 55 wt%, such as at least 65 wt%, such as at least 70 wt%, at least 75 wt%, at least 80 wt%, at least 85 wt%, at least 90 wt%, or about 95 wt% of encapsulated biocide and / or repellent (the "active compound").

[0051] As far as the inventors are aware, aerogels containing such a high and homogeneously distributed amount of encapsulated material have not been disclosed heretofore. Previous attempts to produce highly filled aerogels by the method disclosed in WO 2009 / 062975 resulted in materials with too high a water absorption rate and different porosities and homogeneities compared to the filled aerogels of the present invention. The inventors of the co-pending WO 2020 / 002659 further developed the methodology and in the present application have succeeded in developing a manufacturing method that can accommodate a wider range of biocides / repellents and still maintain the original objectives.

[0052] Therefore, the highly filled gel particles of the present invention make it possible to add large amounts of biocides and / or biocides ( "active compounds") to antifouling coatings and sealants while keeping the amount of silica added simultaneously below the limit of 1.5% w / w previously considered.

[0053] According to the manufacturing procedure disclosed herein, very large amounts of biocides and / or biocides ( "active compounds") can be optionally combined with alkyltrialkoxysilane and used in a two-step procedure with tetraalkoxysilane (monomer tetraalkyl orthosilicate or precondensed tetraalkyl orthosilicate or precondensed monomer tetraalkyl orthosilicate) + active compounds required in the sol-gel preparation (converted to aerogel and dried in the final step). It can be encapsulated in situ in the alcogel formed by

[0054] This new method uses approximately the same ratio of tetraalkoxysilane and alkyltrialkoxysilane as in the original procedure described in International Publication No. WO 2009 / 062975 of the PCT application, but the amount of water used in the gelation process is much less. Furthermore, less ammonia is used as a catalyst, and ammonia is gradually added to the solution of silicate in a separate ethanol solution rather than as a concentrated aqueous solution mixed with the starting materials. Furthermore, an acid catalyst function has also been shown to act, which enables the encapsulation of biocides that are generally sensitive to ammonia or alkaline conditions.

[0055] Compared with the method disclosed in International Publication No. WO 2020 / 002659 of the applicant's co-pending PCT application, a further improvement in the manufacturing process has surprisingly been achieved by performing the SOL-GEL process with large amounts of water and a reverse addition procedure. This enables the encapsulation of biocides / biocides with high solubility in ethanol, and since the melting point of the frozen gel with a high ratio of water in the SOL phase is higher, the resulting gel has the additional advantage of being suitable for freeze-drying.

[0056] Finally, the manufacturing procedure of the present invention differs from that of WO 2020 / 002659 in that the initially formed alcogel (“wet gel”) may be dried using freeze-drying instead of supercritical carbon dioxide extraction. Freeze-drying is a much more commercially viable and scalable procedure than supercritical carbon dioxide extraction. Thus, the aerogel particles by this variation of the manufacturing procedure are isolated as a freeze-dried solid.

[0057] In one embodiment, the wet gel of the present invention can be frozen by any freezing technique known in the art. If the gel is kept in a container used, for example, to age the gel after the SOL-GEL process step, freezing can be carried out by placing the gel in liquid nitrogen, cryogenic mixtures (such as dry ice-acetone bath), or in a refrigerator. Any freezing method will work as long as the gel is at a temperature lower than the freezing temperature of the solvent used for synthesis or solvent exchange. Using tert-butanol as the solvent seems to be particularly advantageous for the freeze-drying procedure because this solvent freezes at approximately room temperature and thus does not need to be cooled to low temperatures (a household freezer is sufficient). However, solvents with low freezing temperatures, such as ethanol, 1-butanol, dimethyl sulfoxide, and carbon tetrachloride, may work. Next, the frozen gel is dried using a conventional freeze dryer or, more simply, placed in a vacuum chamber and pumped out with a conventional rotary pump. However, the part of the chamber containing the sample needs to be maintained at a temperature near the freezing temperature of the solvent to avoid melting, which may lead to the collapse of the aerogel.

[0058] Freeze-drying has been tested at two different temperatures, -18 °C and 80 °C (see Figure 8) and should be considered suitable for scale-up. The resulting aerogel is not different from the material produced by supercritical drying in terms of critical parameters and is more cost-effective.

[0059] These modifications to the procedures described in International Publication No. WO 2009 / 062975 and International Publication No. WO 2020 / 002659 enable the scalable production of filled aerogels with very high loadings (>55% w / w) of a wide variety of active compounds (e.g., biocides and repellents), acceptable water uptake, and much higher homogeneity of the filled gels than obtained with the procedures described in International Publication No. WO 2009 / 062975.

[0060] The resulting aerogel particles typically contain encapsulated active compounds with a content of approximately 55 - 75% w / w, but can be produced with a content of up to approximately 90 - 95% w / w. By varying the ratios between the three starting materials, various porosities, densities, and hydrophobic / hydrophilic behaviors of the final aerogel particles can be obtained. The aerogel particles can also be prepared, by such variations of the method, to match both solvent-based and aqueous coatings and sealants.

[0061] As described above, other physical parameters of the aerogel particles produced according to the invention, such as opacity and thermal conductivity, have also been investigated.

[0062] Any of these parameters are important for the intended final use of the particles: as additives to paints, coatings, and sealants. The opacity of such particles, measured by their "hiding power" (also known as coverage), affects the application efficiency of paints and coatings containing the particles to marine coatings or coatings intended for wood protection or humid indoor environments. The higher the hiding power of the particles, the more efficiently the paint composition covers the surface.

[0063] The thermal conductivity of additives to paints and coatings affects the dissipation of heat through the surface coated with the paint or coating containing the additive. The lower the thermal conductivity of the additive, the better the heat insulation provided. Empty silica aerogel particles are known to reduce the thermal conductivity of coatings. See, for example, F. He et al., “Thermal Conductivity of Silica Aerogel Thermal Insulation Coatings” International Journal of Thermophysics 40(10)October 2019.

[0064] Silica aerogel is known to have a low thermal conductivity (0.005 W / m * K) and be highly porous (about 80 - 99.98%) and optically transparent nanopolymer when measured at temperatures from -175 to 25 °C. See, for example, S.S. Kistler, ‘‘Coherent Expanded Aerogels,’’ The Journal of Physical Chemistry, 1932 or CRC Handbook of Chemistry and Physics.

[0065] Surprisingly, the filled aerogel particles of the present invention have a thermal conductivity in the order of 0.01 - 0.05 W / m * K (see Figure 10) even when containing up to 90% w / w of encapsulated biocide and / or biostatic agent having a thermal conductivity of the order of 0.2 - 0.3 W / m * K as a pure compound. This means that antifouling paints and coatings containing the filled aerogel particles of the present invention have better heat insulation properties than coatings containing non-encapsulated pure biocide and / or biostatic agent.

[0066] The applicant of the present invention compared the thermal conductivity of the filled aerogel particles of the present invention with that of empty aerogel particles prepared according to the method described in International Publication No. WO 2020 / 002659 of the applicant's co-pending application. Surprisingly, these empty aerogel particles of International Publication No. WO 2020 / 002659 (i.e., aerogels containing no encapsulated biocide / biorepellent) have a thermal conductivity of about 0.07 W / m * K, that is, a value significantly higher than the value measured for the filled aerogel particles of the present invention. Without wishing to be bound by theory, the inventors assume that the method of the present applicant results in a material with a lower bulk density and improved content uniformity than that produced by the method disclosed in International Publication No. WO 2020 / 002659.

[0067] In one embodiment, the filled aerogel particles of the present invention have a thermal conductivity of 0.01 to 0.05 W / m * K, for example 0.015 W / m * K to 0.045 W / m * K, for example 0.02 W / m * K to 0.04 W / m * K, for example 0.025 W / m * K to 0.035 W / m * K, for example about 0.03 W / m * K.

[0068] Furthermore, the filled aerogel particles of the present invention were generally found to be opaque using ISO 6504-3:2019, "Determination of hiding power - Part 3: Method C (black and white chart)", the "hiding power" measurement standard for paints and varnishes. Thus, the filled aerogel particles were found to have "hiding power" according to ISO standard 6504-3:2019 (EN) when applied to a clear varnish.

[0069] Monolithic silica aerogels can be prepared using partially condensed silica made from the prepolymerization of tetraalkoxysilanes such as TMOS or TEOS monomers under acidic conditions. The prepolymerized TMOS and TEOS precursors used herein are commercially available.

[0070] Accordingly, in a second aspect, the present invention further provides a method for providing the antifouling additive of the first aspect, comprising the following steps. a. Preparation of Solution 1: Mix 100 parts of tetraalkoxysilane (a mixture of monomeric tetraalkyl orthosilicate or pre-condensed tetraalkyl orthosilicate or pre-condensed monomeric tetraalkyl orthosilicate) with 0 to 50 parts of alkyltrialkoxysilane, 350 to 500 parts of ethanol and 200 to 450 parts of biocide, and stir vigorously with a mixer. Alkoxides containing Sc, Ti, V, Cr, Mn, Fe, Co, Y, Zr, Nb, Ru, Hf, Ta, W, Re, Al, Ge, In, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu can be optionally added at this point. b. Preparation of Solution 2: Mix 100 parts of ethanol, approximately 50 parts of water, and 0.25 to 15 parts of gelling catalyst. c. Slowly add Solution 2 to Solution 1 and stir vigorously for 20 to 25 minutes. Continue stirring at a low speed until signs of gelling are observed, which is approximately 15 minutes later. The resulting solution may be transferred to one or more separate containers for gelling. The gelling time is about 30 to 60 minutes. d. Store the gel in a suitable container for 2 to 5 days and then transfer it to an extractor(s). e. Cut the wet gel into smaller pieces and transfer it to a suitable pressure vessel (a flow reactor equipped with heating jackets and metal frits at both ends) under ethanol. Then, flow ethanol through the gel at a rate of 0.5 mL / min. Next, raise the temperature in the heating jacket to 37 - 40 °C and raise the pressure to 110 - 115 bar (or approximately 80 bar in the case of a biocide soluble in ethanol) at a rate of 3 bar / min for 4 - 8 hours until the ethanol recovery rate is less than 1 ml / min. The exact values of temperature and pressure depend to some extent on the selected packed aerogel but can be easily evaluated by routine experiments. Flow CO2 into the vessel at a rate of approximately 6 mL / min measured at 10 °C. After flowing, release the pressure slowly for 0.5 to several hours.

[0071] In the case of the above steps a - e, ethanol can be easily replaced by another C1 - C4 alcohol such as tert - butanol. Further, as described above, the supercritical drying procedure can be replaced by freeze - drying.

[0072] Thus, according to an embodiment of the method of the present invention, freeze - dried filled aerogels can be produced by first freezing the wet gel produced according to steps a - c above. Next, the frozen gel is placed in a vacuum chamber and the solvent is removed by sublimation. These two steps can be accommodated by a commercially available freeze - dryer.

[0073] Advantages of supercritical drying (only some of which are considered herein) mainly include that the scale - up of the manufacturing procedure is much easier, and in addition, the risk hazards caused by drying under supercritical conditions are reduced. A second advantage of the freeze - drying procedure is a significant reduction in capital expenditure. The autoclaves used for supercritical drying require thick walls and give rise to liability issues due to the high pressures (on the order of 70 atmospheres) used in supercritical drying. In freeze - drying, instead, a much lower - cost production and a vacuum chamber (s) with minimal liability issues are used. Typically, a supercritical drying autoclave costs about 10 times that of a freeze - drying vacuum chamber of the same volume.

[0074] In one embodiment of the manufacturing procedure, Solution 1 contains 20 - 50 parts of an alkyltrialkoxysilane. In another embodiment, particularly when a hydrophilic filled aerogel is envisioned, or when a very high loading of biocide is required, Solution 1 contains less than 20 parts, such as 15 parts, or such as 10 parts, or such as 5 parts or less of an alkyltrialkoxysilane. In another embodiment, Solution 1 does not contain an alkyltrialkoxysilane.

[0075] The tetraalkoxysilanes that may be used in the present invention include alkyl groups in the range of 1 to 4 carbon atoms such as methyl, ethyl, propyl, and butyl. The most preferred tetraalkoxysilanes are tetramethyl orthosilicate (TMOS) and tetraethyl orthosilicate (TEOS).

[0076] In a preferred embodiment, the tetraalkoxysilane is selected from TMOS (tetramethyl orthosilicate), TEOS (tetraethyl orthosilicate), tetra-n-propoxysilane, and tetra-n-butoxysilane.

[0077] In another preferred embodiment, the prehydrolyzed / precondensed tetraalkoxysilane is selected from prehydrolyzed tetramethyl orthosilicate (e.g., Dynasylan® M), prehydrolyzed tetraethyl orthosilicate (e.g., Dynasylan® A), or prehydrolyzed tetra-n-propyl orthosilicate (e.g., Dynasylan® P).

[0078] In a preferred embodiment, the alkyltrialkoxysilane is selected from MTMS (methyltrimethoxysilane) and MTES (methyltriethoxysilane), but other lower alkyltriethoxysilanes such as TMES (trimethylethoxysilane) and ETES (ethyltriethoxysilane) may also be used.

[0079] The gelling catalyst can be any catalyst that is conveniently used for aerogel formation, such as aqueous ammonia (conveniently concentrated NH3 water or 25% in water). Other applicable gelling catalysts include ammonium fluoride, sodium fluoride, and sodium carbonate. Such alternative catalysts are preferred when the biocide may react with ammonia. Acidic catalyst functions can also be used, for example, hydrochloric acid is used especially when the encapsulated biocide is generally sensitive to ammonia or alkaline conditions.

[0080] Examples of the use of various modifications of the general method can be found in the experimental section, including scale-up experiments.

[0081] In a third aspect, there is provided an antifouling additive obtained by the method according to the second aspect.

[0082] In a preferred embodiment, the present invention provides an antifouling additive according to the first or third aspect of the present invention, comprising one or more biocidal or biorepellent compounds selected from the group consisting of pyrithione compounds, basic copper carbonate, isothiazolinone compounds, substituted triazines, carbamates, chlorinated aromatic ureas, triazines, and combinations thereof. Examples of pyrithione compounds include metal pyrithione compounds such as zinc pyrithione, copper pyrithione, zirconium pyrithione, and sodium pyrithione. Examples of isothiazolinone compounds include 4,5-dichloro-2-octyl-4-isothiazolin-3-one (DCOIT), 1,2-benzisothiazolin-3-one (BIT), n-butylisothiazolinone (BBIT), n-octylisothiazolinone (OIT), and mixtures thereof. Examples of substituted triazines include, for example, terbutryn (2-tert-butylamino-4-ethylamino-6-methylthio-1,3,5-triazine). Examples of carbamates include, for example, iodopropynyl butylcarbamate (IPBC). Examples of chlorinated aromatic ureas include, for example, diuron (dichlorophenyl dimethylurea). Among the pyrithione compounds, generally, zinc pyrithione is used from the viewpoints of cost and effectiveness. Those skilled in the art will be able to determine the active ingredients that can be used in the present invention according to the purpose of use of the encapsulated biocidal or biorepellent compounds.

[0083] In one embodiment, the antifouling additive according to the first or third aspect of the present invention is produced by a process including supercritical extraction with CO2. In another embodiment, the antifouling additive according to the first or third aspect of the present invention is produced by a process including freeze-drying.

[0084] As used herein, the term "biocidal or bio-repellent compound" is intended to mean a component having biocidal or bio-repellent properties, including but not limited to active ingredients such as antibacterial, sporicidal, fungicidal, etc.

[0085] The use purpose of the antifouling additive of the present invention is to be added to antifouling coating or sealant compositions applied to wood protection (such as fences, buildings, etc.), marine applications (such as boats, pleasure yachts, commercial ships, oil drilling rigs and other submerged static structures), and humid indoor environments such as bathrooms, toilets, saunas, gyms, indoor swimming pool areas, etc. that are naturally / regularly exposed to moisture and / or water.

[0086] When the prepared aerogel particles are included in the antifouling coating or sealant, the encapsulated active compound is uniformly distributed in the resulting layer. Each aerogel particle may contain several separate particles of the active compound (Figure 3).

[0087] Therefore, in a fourth aspect, there is provided the use of the antifouling additive according to the first or third aspect in a marine coating or a coating for wood protection or a humid indoor environment.

[0088] In a fifth aspect, there is provided an antifouling coating or sealant composition comprising the antifouling additive according to the first or third aspect of the present invention.

[0089] The thickness of the antifouling coating layer is usually about 100 μm, while the sealant is applied at a much greater thickness. However, in either case, as previously discussed, when the antifouling composition is exposed to humid conditions, a layer with a thickness of about 20 - 40 μm that absorbs water from the surroundings gradually develops (Bressy C. et al. “Tin-free self-polishing marine antifouling coatings” Woodshead Publishing, 2009). The thickness of this layer depends on the type of antifouling coating or sealant composition. Solvent-based compositions are, in principle, less likely to absorb water than aqueous compositions. This “wet” layer is called the leaching layer because it is from this layer of the cured composition that the biocidal active compound(s) dissolve and are transported to the surface by diffusion.

[0090] Aerogel particles embedded in the leaching layer of the coating or sealant begin to absorb water due to the porous and hygroscopic nature of silica-based aerogels. This creates a local aqueous environment within the exposed aerogel particles around the entrapped active compound particles, and the active compound particles begin to slowly dissolve. After a while, a saturated solution of the active compound is formed within the aerogel particles (Figure 4).

[0091] This saturated solution then functions as a reservoir for the active compound, and release to the surface of the antifouling coating or sealant occurs when the active compound penetrates through the porous structure of the aerogel particles and exits onto the surface of the antifouling coating or sealant. The leaching layer is constantly regenerated by erosion of the upper part of the layer as the coated surface is passed through by water or (in the case of static outdoor applications) exposed to rain, sunlight, and temperature fluctuations. In the case of indoor applications, erosion would be caused by periodic exposure to water such as in showers and physical cleaning of the surface with detergents to which the antifouling composition has been applied. As a result, the leaching layer decreases in thickness due to erosion from the top, but is simultaneously regenerated by including regions deeper within the antifouling composition layer.

[0092] By erosion and regeneration of the leaching layer, it is ensured that a sufficient amount of biocide is always present to maintain the desired antifouling effect on the surface of the dried antifouling composition throughout the entire service life of the dried antifouling composition.

[0093] When the leaching layer is eroded, the embedded aerogel particles gradually become exposed to the environment. However, even when partially exposed, the aerogel particles remain adhered in the antifouling composition (along with their remaining biocide content) until they are ultimately removed by erosion of the coating or sealant, as previously discussed. This is a significant difference from the situation shown in Figure 1, which indicates that uncaught biocide particles are lost from the coating well before they are fully utilized to exert an antifouling effect.

[0094] As long as undissolved active compounds are present inside the aerogel particles, thereby ensuring a saturated reservoir of dissolved active compounds, the release to the surface occurs at a substantially zero-order reaction rate. In other words, the release profile over time is substantially linear.

[0095] Accordingly, the concentration of biocide / biocidal repellent on the surface of the antifouling coating is maintained substantially constant throughout the expected service life of the coating or sealant, as long as the surface is regularly exposed to moisture such as moist air, particularly air with a relative humidity exceeding 65%, rain, or contact with water. If multiple biocides / biocidal repellents are required, each active compound can be individually encapsulated and included in the antifouling composition in the correct ratio, ensuring that the individual active compounds do not interact during storage and that a constant ratio between the compounds released from the final coating or sealant is maintained throughout its expected service life.

[0096] In a preferred embodiment, the present invention provides an antifouling coating composition comprising an antifouling additive according to the present invention in an amount corresponding to at least 2% w / w of a biocide, such as at least 3% w / w of a biocide, at least 4% w / w of a biocide, such as at least 5% w / w of a biocide, such as at least 6% w / w of a biocide, such as at least 7% w / w of a biocide.

[0097] In a further embodiment of the present invention, there is provided an antifouling coating comprising two or more different biocides and / or biorepellents, individually encapsulated within different aerogels and then added to the antifouling composition in the required ratios.

[0098] The procedures described herein have been found to function well for many distinct chemical structures such as pyrithione, isothiazole and isothiazolone, triazole, imidazole and benzimidazole, halogenated pyrrole, urea, carbamate, sulfamide, and zinc and copper salts (such as zinc thiocarbamate), copper thiocyanate, copper(II) hydroxide and copper(II) carbonate - copper(II) hydroxide (1:1) and metallic copper. In one embodiment, the encapsulated biocidal or biorepellent compound is selected from pyrithiones of the following formula:

[0099]

Chemical formula

[0100] wherein Met is a metal selected from copper, zinc, zirconium, or sodium.

[0101] In a preferred embodiment, the encapsulated biocidal or biorepellent compound is selected from zinc pyrithione, copper pyrithione or sodium pyrithione. In another embodiment, the encapsulated biocidal or biorepellent compound is selected from isothiazoles of the following formula:

[0102]

Chemical formula

[0103] Wherein, R1 and R2 may be halogen or hydrogen, or R1 and R2 may fuse to form an optionally further substituted aromatic ring and R3 = C3-C 12 alkyl may be formed.

[0104] In certain embodiments, the biocidal or biorepellent compound is selected from 2-butyl-benzothiazole-3-one (BBIT), 2-octyl-2H-isothiazole-3-one (OIT), or 4,5-dichloro-2-octylisothiazole-3(2H)-one (DCOIT, Sea-Nine).

[0105] In another embodiment, the encapsulated biocidal or biorepellent compound is selected from triazoles of the following formula:

[0106]

Chemical formula

[0107] Wherein, R4 = hydrogen, C1-C6 alkyl, R5 = C1-C6 alkyl, C1-C6 alkyloxy, R6 = aryl, C1-C6 arylalkyl, and R4 and R5 may fuse to form a 5- to 6-membered ring containing at least one oxygen.

[0108] In certain embodiments, the biocidal or biorepellent compound is selected from 1-(4-chlorophenyl)-4,4-dimethyl-3-(1,2,4-triazol-1-yl-methyl)pentan-3-ol (tebuconazole), 1-[[2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl]methyl]-1H-1,2,4-triazole (propiconazole), or (2RS,3RS,2RS,3SR)-2-(4-chlorophenyl)-3-cyclopropyl-1-(1H-1,2,4-triazol-1-yl)butan-2-ol (cyproconazole).

[0109] In another embodiment, the encapsulated biocidal or biorepellent compound is selected from triazines of the following general formula:

[0110]

Chemical formula

[0111] wherein R7 = C1-C6 alkylthio, R8 = C1-C6 alkylamino, and R9 = C1-C6 alkylamino.

[0112] In a preferred embodiment, the biocidal or biorepellent compound is 2-ethylamino-6-methylthio-4-tert-butylamino-1,3,5-triazine (terbutryn).

[0113] In another embodiment, the encapsulated biocidal or biorepellent compound is selected from imidazoles of the following general formula:

[0114]

Chemical formula

[0115] wherein R 10 and R 11 may be hydrogen, C1-C6 alkyl or C1-C3 arylalkyl, or may fuse to form a benzimidazole ring, and R 12 = hydrogen, heteroaryl or carbamoyl.

[0116] In certain embodiments, the biocidal or biorepellent compound is selected from 2-thiazol-4-yl-1H-benzimidazole ( thiabendazole), (RS)-4-[1-(2,3-dimethylphenyl)ethyl]-3H-imidazole (medetomidine), and methyl 1H-benzimidazol-2-ylcarbamate (carbendazim).

[0117] In another embodiment, the encapsulated biocidal or biorepellent compound is selected from halogenated pyrroles of the following general formula:

[0118]

Chemical formula

[0119] wherein R 13 = aryl, R 14 = halogen, cyano, trifluoromethylsulfonyl, R 15 = halogen, trifluoromethylthio, R 16 = cyano, trifluoromethyl, halogen, R 17 = hydrogen, C2-C6 alkyloxymethyl, and R 14 , R 15 and R 16 at least one of which is halogen.

[0120] In certain embodiments, the biocidal or biorepellent compound is selected from 4-bromo-2-(4-chlorophenyl)-5-(trifluoromethyl)-1H-pyrrole-3-carbonitrile (tolclofos-methyl) and 4-bromo-2-(4-chlorophenyl)-1-ethoxymethyl-5-trifluoromethylpyrrole-3-carbonitrile (chlorfenapyr). In another embodiment, the encapsulated biocidal or biorepellent compound is selected from carbamates, ureas or sulfamides of the following general formula:

[0121]

Chemical formula

[0122] wherein Q = carbonyl (C=O) or sulfonyl (O=S=O), R 18 = aryl, C1-C8 alkyl, hydrogen, and R 19 = C1-C6 alkyl, hydrogen, G = O-R 20 or N(R 21 R 22 )(wherein R20 = C3-C6 alkynyl, C1-C6 alkyl, R 21 = C1-C8 alkyl, trihalomethylthio, hydrogen, and R 22 = C1-C8 alkyl, aryl, hydrogen).

[0123] In a further embodiment, the biocidal or biorepellent compound is selected from carbamates, ureas or sulfamides of the following three general formulas, respectively:

[0124]

Chemical formula

[0125] Wherein R 18 = aryl, C1-C8 alkyl, hydrogen and R 19 = C1-C6 alkyl, hydrogen, R 20 = C3-C6 alkynyl, C1-C6 alkyl, R 21 = C1-C8 alkyl, trihalomethylthio, hydrogen, and R 22 = C1-C8 alkyl, aryl, hydrogen.

[0126] In certain embodiments, the biocidal or biorepellent compound is selected from 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron), dichloro-N-[(dimethylamino)-sulfonyl]-fluoro-N-(p-tolyl)-methanesulfenamide (tolylfluanid), N-(dichlorofluoromethylthio)-N’,N’-dimethyl-N-phenylsulfamide (dichlofluanid), 3-iodo-2-propynyl butylcarbamate (iodocarb).

[0127] In yet another embodiment, the encapsulated biocidal or biorepellent compound is selected from zinc salts and copper salts such as zinc thiocarbamate, copper thiocyanate, copper(II) hydroxide and copper(II)-copper(II) (1:1), and metallic copper.

[0128] In a particularly preferred embodiment, the encapsulated biocidal or biorepellent compound is selected from triolfluanid, N,N-didecyl-N,N-dimethylammonium carbonate, N,N-didecyl-N,N-dimethylammonium bicarbonate, zinc pyrithione, copper pyrithione, diuron, 4,5-dichloro-2-octyl-4-isothiazolin-3-one (= Sea-Nine or DCOIT), 3-iodo-2-propynyl butylcarbamate (IPBC), 2-thiazol-4-yl-1H-benzimidazole ( thiabendazole), 2-(p-chlorophenyl)-3-cyano-4-bromo-5-trifluoromethylpyrrole (= Econea or tralopyril) or mixtures thereof.

Example

[0129] Experiment Materials used in aerogel synthesis The gel-forming material is selected from metal oxides based on Si, Ti, Fe, and Al such as tetramethyl orthosilicate (TMOS, tetramethoxysilane) or tetraethyl orthosilicate (TEOS, tetraethoxysilane). To produce a more hydrophobic material, methyltrimethoxysilane (MTMS or the like) may be included. The prepolymerized (prehydrolyzed, precondensed) tetraalkoxysilane is commercially available or can be produced by hydrolyzing the relevant tetraalkoxysilane under weakly acidic conditions and then polymerizing overnight at low temperature.

[0130] General methods used to prepare aerogels containing encapsulated biocides / biorepellents To accommodate a wide selection of biocides / biorepellents with various solubilities and resistance to acidic or alkaline conditions and to enable the use of various combinations of tetraalkoxysilane and alkyltrialkoxysilane, the following methods have been developed for generating the encapsulated biocides / biorepellents of the present invention.

[0131] ·Original formulation (International Publication No. 2020 / 002659) Dynasylan M / TMOS gel (used for encapsulating compounds with low solubility in ethanol / alcohol (e.g., CPT, ZPT, dinneb, diuron)) 1. Mix Dynasylan M, MTMS (with or without), and EtOH with a magnetic stirrer for 10 minutes. Add the biocide and mix vigorously for approximately 5 minutes or until uniform mixing is achieved. 3. Mix NH4OH with EtOH + water and add it to the biocide mixture while stirring. 4. Reduce the stirring speed until the reaction mixture becomes bulky like a purine (this takes approximately 15 - 25 minutes). 5. Close the container and add a small amount of ethanol on top of the gel to avoid drying. Leave the material to mature for approximately 3 days (this can be done in a refrigerator).

[0132] The resulting gel material is suitable for drying with supercritical CO2. To lyophilize the gel material, it is necessary to use an alcohol with a higher melting point, such as tert-butanol, instead of ethanol at the wet stage. Refer to the section on general drying methods below.

[0133] ·Preparation of gel - gel containing ammonium fluoride - TEOS / Dynasylan A (e.g., CPT, ZPT, dinneb, diuron, Econea)

[0134] Preparation of stock solution 1. Weigh 1.852 g of NH4F and add it to 100 mL of water. Add 20.50 g (22.78 mL) of ammonium hydroxide solution. Store this in a bottle for later reuse. This is the "ammonium fluoride / ammonium hydroxide stock solution".

[0135] Preparation of gel 1. Put Dynasylan A / TEOS and ethanol in a bottle and mix. Mix for 10 minutes. This is the "alkoxide solution". 2. Add a biocide to the alkoxide solution. Stir for 5 minutes. 3. Mix water and ethanol in a separate container. Add the ammonium fluoride / ammonium hydroxide stock solution. This mixture is the "catalyst solution". 4. Pour the catalyst solution into the alkoxide solution and stir. This is the "sol". 5. Stir until the magnet stops moving, or pour the sol into a mold to form a gel. The gelation time is about 8 - 40 minutes. The gelation time depends on the alcohol / water ratio and the (DynA + MTMS) to (water + ethanol) ratio. 6. Close the container and the material can be left to age for approximately 3 days (it can be done in a refrigerator).

[0136] This gel material is suitable for lyophilization as long as the freezing point / melting point is maintained above -60°C.

[0137] This gel material is suitable for drying with supercritical CO2 as long as the water content is low. Otherwise, for example, tert-butanol needs to be used instead of ethanol.

[0138] · Gel preparation - in reverse order of high water ratio (for cases such as Iodocarb, Terbutryn, Tolyfluanid due to ethanol solubility / miscibility) 1. Put water, ethanol, a dispersant (and an antifoaming agent) into a bottle and mix. Mix it with a magnetic stirrer for 10 minutes. 2. Add the biocide. Stir for 10 minutes. 3. Mix TMOS (and MTMS) in a separate container. 4. Pour TMOS / MTMS into the EtOH / aqueous solution / biocide and stir for 5 minutes. 5. Add NH4OH - basic catalyst. 6. Stir until the magnet stops moving, or pour the sol into a mold to form a gel. 7. Close the container and the material can be left to age for approximately 3 days (it can be done in a refrigerator).

[0139] This gel material is suitable for freeze-drying.

[0140] · Preparation of gel - Acid (required for DCOIT etc., ethanol miscible, unstable, and alkali sensitive) 1. Put water, ethanol, and dispersant into a bottle and mix. Mix it with a magnetic stirrer for 10 minutes. 2. Add HCL and mix for 10 minutes. 3. Add the biocide. Stir for 10 minutes. 4. Mix Dynasylan A and MTMS in another container. 5. Pour DynA / MTMS into the EtOH / aqueous solution / biocide and stir for 5 minutes. 6. Add NH4OH - basic catalyst. 7. Stir until the magnet stops moving, or pour the sol into a mold to form a gel. 8. Close the container and the material can be left to age for approximately 3 days (it can be done in the refrigerator).

[0141] This material is suitable for freeze-drying.

[0142] · General drying method including solvent exchange After pouring into an airtight type, age all the gels at room temperature for 1 - 3 days. In the case of supercritical drying, cut the wet gel into smaller pieces, transfer it to a pressure vessel (a flow reactor equipped with heating jackets and metal frits at both ends) under ethanol, and optionally flow ethanol at 0.5 mL / min.

[0143] Next, raise the temperature in the heating jacket to 37 - 40 °C and raise the pressure to 80 - 120 bar at a rate of 3 bar / min. Flow CO2 into the reactor at a rate of approximately 6 mL / min measured at 10 °C for 3 - 4 hours (maximum 8) at 40 °C and 110 bar until the ethanol recovery rate is less than 1 ml / min. After flowing, release the pressure slowly over 0.5 - several hours.

[0144] Depending on the composition of the SOL phase, before freeze-drying, the solvent in the wet gel can be exchanged with tert-butanol (4 times the volume of the gel, 3 times every 4 hours). In the case of a wet gel with a high water ratio, it is not necessary to exchange the solvent before freezing. In the case of a wet gel with a high ethanol ratio, by performing solvent exchange with tert-butanol before freezing, subsequent freeze-drying at a higher temperature becomes possible. This is suitable for large-scale operations.

[0145] Freeze-drying was carried out at -18 °C or -80 °C in a commercially available freeze-dryer (VirTis model Benchtop K). The gel containing tert-butanol was frozen at -18 °C in a commercial refrigerator and freeze-dried at a shelf temperature of about -7 °C and a pressure of <3 Torr. In the case of such gels, the freezing temperature is usually -18 °C or lower. The frozen gel is freeze-dried in a vacuum chamber that maintains a temperature near the freezing temperature selected at the start of the primary drying stage. During the drying process, the temperature can be slowly increased.

[0146] Examples 1, 2, 3, 3a, 3b, 4 and 6 are reference examples. Example 1. Preparation of an aerogel containing approximately 75% encapsulated biocide (ZnP)

[0147] 1. Solution 1: 0.64 kg of precondensed TMOS (tetramethyl orthosilicate) such as Dynasylan M or pure TMOS, 0.32 kg of MTMS (methyltrimethoxysilane), 3.2 kg of ethanol, and 1.44 kg of zinc pyrithione were mixed in a 10-liter container and stirred vigorously with a paddle mixer until homogeneous. 2. Solution 2: Mix 0.64 kg of ethanol, 0.32 kg of water, and 10 ml of ammonia solution (concentrated). 3. Add Solution 2 to Solution 1 at 500 rpm for 10 - 25 minutes under the same mixing conditions as (1). Lower the mixing speed to about 100 rpm until signs of gelation appear within approximately 15 minutes. The gelation time is approximately 30 minutes. 4. Store the gel in a plastic container for 3 - 5 days and then transfer it to an extraction device (s). The wet gel from (5.3) is cut into smaller pieces and transferred to a 5 or 10 L pressure vessel (a flow reactor equipped with heating jackets and metal frits at both ends) under ethanol. Ethanol can be flowed through the gel at 0.5 mL / min, but it is not essential. Next, the temperature in the heating jacket is raised to 37 - 40 °C, and the pressure is raised to 110 - 115 bar at a rate of 3 bar / min. Maintain at 37 - 40 °C and 110 bar for 3 - 4 hours (maximum 8) until the ethanol recovery rate is less than 1 ml / min. CO2 is flowed into the vessel at a rate of approximately 6 mL / min measured at 10 °C. After flowing, the pressure is slowly released over 0.5 - several hours. The weight of the supercritical dried aerogel was approximately 1.9 kg.

[0148] Example 2. Preparation of an aerogel containing approximately 80% encapsulated biocide (CuP) 1. Solution 1: Mix 0.96 kg of pre - condensed TMOS such as Dynasylan M or pure TMOS (tetramethyl orthosilicate), 3.2 kg of ethanol, and 1.77 kg of copper pyrithione in a 10 - liter container and stir vigorously with a paddle mixer until homogeneous. 2. Solution 2: Mix 0.64 kg of ethanol, 0.32 kg of water, and 10 ml of ammonia solution (concentrated). 3. Add Solution 2 to Solution 1 at 500 rpm for 10 - 25 minutes under the same mixing conditions as (1). Reduce the mixing speed (to 100 rpm) until signs of gelation appear, which is approximately 15 minutes. The gelation time is approximately 30 minutes. 4. Store the gel in a plastic container for 3 - 5 days and then transfer it to an extraction device(s). The wet gel from (3) is cut into smaller pieces and transferred to a 5 or 10 L pressure vessel (a flow reactor equipped with heating jackets and metal frits at both ends) under ethanol. Ethanol can be flowed through the gel at 0.5 mL / min, but it is not essential. Next, the temperature in the heating jacket is raised to 37 - 40 °C, and the pressure is raised to 110 - 115 bar at a rate of 3 bar / min. At 37 - 40 °C and 110 bar for 3 - 4 hours (maximum 8) until the ethanol recovery rate is less than 1 ml / min. CO2 is flowed into the vessel at a rate of approximately 6 mL / min measured at 10 °C. After flowing, the pressure is slowly released over 0.5 - several hours. The weight of the supercritical dried aerogel was approximately 2.2 kg.

[0149] Example 3. Preparation of an aerogel containing approximately 80% encapsulated ZnP from pre - condensed TMOS 1. Solution 1: 10.5 g of pre - condensed TMOS, 5.2 g of MTMS, and 45 g of ethanol were stirred in an Erlenmeyer flask with a magnetic stirrer for approximately 15 minutes. 30.0 g of zinc pyrithione was added during mixing. The solution was mixed for an additional 15 minutes. 2. Solution 2: Mix 18 g of ethanol, 1.5 g of water, and 300 μl of ammonia solution (concentrated). 3. While mixing at full speed (1500 RPM) with a magnetic stirrer, Solution 2 was added to Solution 1. After mixing for an additional 2 - 5 minutes, the white opaque solution was transferred to a blue - capped bottle. Approximately 45 minutes later, gelation occurred, and the resulting gel was aged in ethanol at room temperature for 2 - 3 days and then dried. The wet gel from 4.3) is cut into smaller pieces and transferred to a 5 or 10 L pressure vessel (a flow reactor equipped with heating jackets and metal frits at both ends) under ethanol. Ethanol can be flowed through the gel at 0.5 mL / min, but this is not essential. Next, the temperature in the heating jacket is raised to 37 - 40 °C and the pressure is raised to 110 - 115 bar at a rate of 3 bar / min. Hold at 37 - 40 °C and 110 bar for 3 - 4 hours (maximum 8) until the ethanol recovery rate is less than 1 ml / min. CO2 is flowed into the vessel at a rate of approximately 6 mL / min measured at 10 °C. After flowing, the pressure is slowly released over 0.5 - several hours. The weight of the supercritically dried aerogel was 37.5 g.

[0150] Example 3.a. Preparation of an aerogel containing approximately 76% encapsulated ZnP from pre - condensed TEOS 1. Solution 1: 33.16 g of pre - condensed TMOS (or pure TEOS) and 93 g of ethanol were stirred in a Erlenmeyer flask with a magnetic stirrer for approximately 15 minutes. 40.25 g of zinc pyrithione was added during mixing. The solution was mixed for an additional 15 minutes. 2. Solution 2: 36 g of ethanol, 74 g of water, 2.8 g of catalyst base (weigh 1.852 g of NH4F and add to 100 mL of water. Add 20.50 g (22.78 mL) of ammonium hydroxide solution. Store this in a bottle for later reuse. This is the mixed "catalyst base"). 3. While mixing at full speed with a magnetic stirrer, Solution 2 was added to Solution 1. After mixing for an additional 8 - 15 minutes, the white opaque solution was transferred to a blue - capped bottle. Gelation occurred after approximately 15 minutes, and the resulting gel was aged in ethanol for 3 - 5 days and then dried. The wet gel from 4.3) was cut into smaller pieces and transferred to a 0.5 L pressure vessel (a 0.5 L flow reactor equipped with heating jackets and metal frits at both ends) under ethanol. Ethanol can flow through the gel at a rate of 0.5 L at 0.5 mL / min, but it is not essential. Next, the temperature in the heating jacket was raised to 37 - 40 °C, and the pressure was raised to 100 bar at a rate of 3 bar / min. After about 4 hours at approximately 40 °C and 100 bar, 2.5 kg of CO2 was flowed into the vessel at a rate of about 6 mL / min. After flowing, the pressure was slowly released over 1 hour. The weight of the supercritical dried aerogel was approximately 53 g.

[0151] Example 3.b Preparation of an aerogel containing approximately 76% encapsulated ZnP from pre - condensed TEOS and MTMS 1. Solution 1: 21.3 g of pre - condensed TMOS (or pure TEOS), 11.86 g of MTMS, and 93 g of ethanol were stirred in a triangular flask with a magnetic stirrer for approximately 15 minutes. 40.25 g of zinc pyrithione was added during mixing. The solution was mixed for an additional 15 minutes. 2. Solution 2: 36 g of ethanol, 74 g of water, 2.84 g of catalyst base (weigh 1.852 g of NH4F and add it to 100 mL of water. Add 20.50 g (22.78 mL) of ammonium hydroxide solution. Store this in a bottle for later reuse. This is the 'catalyst base'), and mix. 3. While mixing at full speed with a magnetic stirrer, Solution 2 was added to Solution 1. After mixing for an additional 8 - 15 minutes, the white opaque solution was transferred to a blue - capped bottle. Gelation occurred after approximately 104 minutes, and the resulting gel was aged in ethanol for 3 - 5 days and then dried. The wet gel from (4.3) was cut into smaller pieces and transferred to a 0.5 L pressure vessel (a 0.5 L flow reactor equipped with heating jackets and metal frits at both ends) under ethanol. Ethanol can flow through the gel at a rate of 1 / 2 L at 0.5 mL / min, but it is not essential. Next, the temperature in the heating jacket was raised to 37 - 40 °C, and the pressure was raised to 100 bar at a rate of 3 bar / min. After about 4 hours at approximately 37 - 40 °C and 100 bar, 2.5 kg of CO2 was flowed into the vessel at a rate of about 6 mL / min. After flowing, the pressure was slowly released over 1 hour. The weight of the supercritically dried aerogel was approximately 53 g.

[0152] Example 4. Preparation of an aerogel containing encapsulated diuron from pre - condensed TMOS 1. Solution 1: A mixture of 10.5 g of pre - condensed TMOS, 5.2 g of MTMS, and 45 g of ethanol is stirred in an Erlenmeyer flask with a magnetic stirrer for 15 minutes. During mixing, 12 g of diuron was added. The solution was mixed for an additional 15 minutes. 2. Solution 2: Mix 18 g of ethanol, 1.5 g of water, and 0.8 g of ammonia solution. 3. While mixing at full speed (1500 RPM) with a magnetic stirrer, Solution 2 was added to Solution 1. After mixing for an additional 2 - 5 minutes, the white opaque solution was transferred to a blue - capped bottle. After approximately 0.5 hour, gelation occurred, and the resulting gel was aged in ethanol at room temperature for 2 - 3 days and then dried. 4. The wet gel from (4.3) was cut into smaller pieces and transferred to a 0.5 L pressure vessel. Next, the temperature in the heating jacket was raised to 37 - 40 °C, and the pressure was raised to 100 bar at a rate of 3 bar / min. After 4 hours at 37 - 40 °C and 100 bar, 2.5 kg of CO2 was flowed into the vessel at a rate of about 6 mL / min measured at 10 °C. After flowing, the pressure was slowly released over 1 hour. The weight of the supercritically dried aerogel was approximately 20 g, which corresponds to approximately 60 wt% of diuron.

[0153] Example 4.b. Preparation of an aerogel containing encapsulated diuron from pre - condensed TEOS 1. Solution 1: A mixture of 10.72 g of pre - condensed TEOS, 6.09 g of MTMS, and 28.45 g of ethanol is stirred in a triangular flask with a magnetic stirrer for 15 minutes. During mixing, 12.29 g of diuron is added. The solution is mixed for an additional 15 minutes. 2. Solution 2: Mix 28.45 g of ethanol, 22.95 g of water, 1.19 g of stock solution base (weigh 1.852 g of NH4F and add it to 100 mL of water. Add 20.50 g (22.78 mL) of ammonium hydroxide solution. Store this in a bottle for later reuse. This is the "catalyst base"). 3. While mixing at full speed with a magnetic stirrer, Solution 2 is added to Solution 1. After approximately 40 minutes, gelation occurs, and the resulting gel is aged in ethanol for approximately 3 days during drying. 4. Samples of the wet gel from 3) are freeze - dried at - 80 °C and 18 °C. Both samples are analyzed by Mercury Intrusion Porosimetry. The remaining wet gel from 3) is cut into smaller pieces and transferred to a 0.5 L pressure vessel (a 0.5 L flow reactor equipped with heating jackets and metal frits at both ends) under ethanol. Next, the temperature in the heating jacket is raised to 37 - 40 °C, and the pressure is raised to 100 bar at a rate of 3 bar / min. After 4 hours at 37 - 40 °C and 100 bar, 2.5 kg of CO2 is flowed into the vessel at a rate of approximately 6 mL / min measured at 10 °C. After flowing, the pressure is slowly released over 1 hour. The weight of the supercritical - dried aerogel is approximately 35 g, which corresponds to approximately 65 wt% of diuron.

[0154] Example 5. Preparation of an aerogel containing approximately 75% encapsulated IPBC from pre - condensed TMOS or TEOS 1. Solution 1: A mixture of 14 g of pre - condensed TMOS or TEOS, 7 g of MTMS, and 60 g of ethanol is stirred in a triangular flask with a magnetic stirrer for 15 minutes. During mixing, 35.0 g of IPBC (3 - iodo - 2 - propynyl butylcarbamate) is added. The solution is mixed for an additional 15 minutes. 2. Solution 2: Mix 24 g of ethanol, 2 g of water, and 1.9 ml of ammonia solution (concentrated). 3. While mixing at full speed (1500 RPM) with a magnetic stirrer, add Solution 2 dropwise to Solution 1. After mixing for an additional 2 minutes, transfer the white opaque solution to a blue cap bottle. After approximately 180 minutes, gelation occurs. The resulting gel is aged in ethanol at room temperature for 2 - 3 days and then dried. The amount of ammonia solution can be reduced to 1 g to extend the gelation time. 4. Cut the wet gel from (3) into smaller pieces and transfer it to a 0.5 L pressure vessel (a 0.5 L flow reactor equipped with heating jackets and metal frits at both ends) under ethanol (or higher alcohol). There, flow 0.5 L of ethanol through the gel at a rate of 0.5 mL / min. Next, raise the temperature in the heating jacket to 37 - 40 °C and increase the pressure to 110 bar at a rate of 3 bar / min. After 4 hours at 40 °C and 110 bar, flow 2.5 kg of CO2 into the vessel at a rate of approximately 6 mL / min measured at 10 °C. After flowing, release the pressure slowly over 0.5 - several hours. Yield of supercritical dried aerogel: Approximately 47 g (containing approximately 75 w / w% of IPBC).

[0155] Example 5. Preparation of an aerogel containing approximately 75% encapsulated IPBC from TMOS and / or TEOS 1. Solution 1: Mix 3.1 g of ethanol, 60.9 g of water, 1.9 ml, 2 g of a dispersant (Tego disperses 740W), and 1 g of an antifoaming agent (Foamex 1488). Add 15.97 g of iodocarb (3 - iodo - 2 - propynyl butylcarbamate) and stir for 5 minutes. 2. Solution 2: Stir a mixture of 14 g of TMOS and 14 g of TEOS in a container with a magnetic stirrer for 5 minutes. 3. Add Solution 2, which is mixed at full speed with a magnetic stirrer, to Solution 1. After mixing for an additional 5 minutes, add the catalyst solution and mix until gelation occurs. Age the gel in the refrigerator for 2 - 3 days and then dry it. 4. Freeze-drying is preferred for the amount of water. The theoretical w / w% of the biocide in the gel is approximately 56 w / w%. The total amount of the gel is estimated to be 29 g.

[0156] Preparation of an aerogel containing encapsulated terbutryn from TMOS - Example 5.b 1. Solution 1: Mix 50 g of water, 3 g of ethanol, 2.52 g of a dispersant (Tego disperses 740W), and 1 g of an antifoaming agent. Add 15 g of terbutryn and stir for 5 minutes. 2. Solution 2: Stir a mixture of 20 g of TMOS (or pre-condensed) and 10 g of MTMS in another container with a magnetic stirrer for 5 minutes. 3. While mixing at full speed with a magnetic stirrer, add Solution 2 to Solution 1. After mixing for an additional 5 minutes, pour 0.4 g of a catalyst (NH4OH) into the mixture. After gelation, allow the resulting gel to age for approximately 3 days and then dry. The amount of ammonia solution can be reduced to extend the gelation time. 4. Freeze-drying is preferred for the amount of water. The theoretical w / w% of the biocide in the gel is approximately 56 w / w%. The total amount of the gel is estimated to be 27 g.

[0157] Preparation of an aerogel containing approximately 75% encapsulated DCOIT from pre-condensed TMOS - Example 6 1. Solution 1: Stir a mixture of 17.5 g of pre-condensed TMOS, 3.2 g of MTMS (or DEDMS), and 60 g of ethanol in an Erlenmeyer flask with a magnetic stirrer for 15 minutes. Add 30.0 g of DCOIT (4,5-dichloro-2-octyl-4-isothiazolin-3-one) during mixing. Mix the solution for an additional 15 minutes. 2. Solution 2: Mix 24 g of ethanol, 2 g of water, and 9 ml of HCl. 3. While mixing at full speed with a magnetic stirrer, Solution 2 was added to Solution 1. After further mixing for 2 - 5 minutes, the white opaque solution was transferred to a blue cap bottle. After gelation occurred, the resulting gel was aged in ethanol at room temperature for 2 - 3 days and then dried. 4.3) The wet gel from (4.3) was cut into smaller pieces and transferred to a 0.5 L pressure vessel (a 0.5 L flow reactor equipped with heating jackets and metal frits at both ends) under ethanol. There, 0.5 L of ethanol was flowed through the gel at a rate of 0.5 mL / min. Next, the temperature in the heating jacket was raised to 37 - 40 °C, and the pressure was raised to 90 bar at a rate of 3 bar / min. After 4 hours at 35 °C and 90 bar, 2.5 kg of CO2 was flowed into the vessel at a rate of approximately 6 mL / min measured at 10 °C. After flowing, the pressure was slowly released over 0.5 - several hours. Yield of supercritical dried aerogel: approximately 40 g (containing approximately 75 w / w% of DCOIT).

[0158] Example 7. Preparation of an aerogel containing encapsulated trifulanide from pre - condensed TMOS / TEOS 1. Solution 1: 50 g of water, 3 g of ethanol, 2.52 g of a dispersant (Tego disperses 740W), and 1 g of an antifoaming agent were mixed. 15 g of trifulanide was added and stirred for 5 minutes. 2. Solution 2: A mixture of 20 g of TMOS (or pre - condensed) and 10 g of MTMS was stirred in another container with a magnetic stirrer for 5 minutes. 3. While mixing at full speed with a magnetic stirrer, Solution 2 was added to Solution 1. After further mixing for 5 minutes, 0.4 g of a catalyst (NH4OH) was poured into the mixture. After gelation, the resulting gel was aged for approximately 3 days and then dried. The amount of ammonia solution can be reduced to extend the gelation time. Freeze - drying is preferred due to the amount of water. The theoretically w / w% of the biocide in the gel is approximately 56 w / w%. The total amount of the gel is estimated to be 27 g.

[0159] Example 8. Mercury porosimetry measurement Background:

[0160] In mercury intrusion porosimetry, a dry sample of the loaded aerogel is placed in a container, which is then evacuated and purged of contaminant gases and vapors (usually water). While the container is still evacuated, it can be filled with mercury, creating a system composed of a solid, a non-wetting liquid (mercury), and mercury vapor. In the next step, the pressure is increased towards ambient. This causes mercury to enter the larger openings of the aerogel sample, and the amount thereof is reflected in the volume change. Next, the sample container is placed in a pressure vessel and attached to a pressurization system, which can increase the pressure of the system up to about 60,000 psi (414 MPa), a typical maximum value for commercial equipment. This forces mercury into small pores with a diameter of about 0.003 μm. Regardless of the pore shape and the model employed to quantify it, the amount of mercury forced into the interconnected pores of the aerogel sample increases as the pressure increases. Mercury intrusion is not suitable for the analysis of the pore structure of empty aerogels, because their solid frameworks may collapse under high compressive forces.

[0161] Mercury intrusion porosimetry provides information regarding many aspects of the pore structure of aerogels, particularly the porosity (%), defined as the volume of the void (empty) space of the sample divided by the total volume of the sample. It is also the amount of intrusion (ml / g), which is a measure of the interconnected porous portion of the sample.

[0162] Example 8a. Measurement of ZnP-containing aerogels In this experiment, five different aerogel samples (1A, 1B, 1C, 2A, and 2B), all containing 75% ZnP, were tested by mercury intrusion porosimetry for various pore-related parameters. Samples 1A, 1B, and 1C were prepared using normal silicate under various process conditions, and samples 2A and 2B were prepared using precondensed TMOS.

[0163] When defining the differences between aerogels produced using either normal tetraalkoxysilane or precondensed silicate, it was found that both the bulk density and the intrusion volume were highly descriptive. See Figure 7.

[0164] From the experiments conducted in Example 8a, it can be concluded that the ZnP-containing aerogel prepared with precondensed TMOS has a significantly lower bulk density and a significantly higher intrusion volume than a similar aerogel produced from normal silicate. On the other hand, the porosity and oil number of the two gels do not show a similar trend.

[0165] Example 8b. Measurement of Aerogels Containing Other Biocides For all samples, the content of the encapsulated biocide was evaluated by thermogravimetric analysis (TGA) measurements. For ZnP and CuP, a good agreement was found between the amount of biocide intended to be trapped within the aerogel and the amount actually present in the aerogel as measured by TGA (77% and 76% respectively, compared to 75% intended).

[0166] Aerogels for Method Feature Evaluation Gel Characteristics Mercury Intrusion Analysis High-pressure mercury (Hg) intrusion analysis was performed on a Micromeritics Autopore V instrument (initial measurement: Autopore IV model 9520 or similar). Samples were measured in a pressure range of 0.5 psia to 30000 psia corresponding to a pore size scan from 338 μm to 6.6 nm. 1. All samples were loaded into a penetrometer specially designed for analyzing powder samples (i.e., 5 ml capacity, 1.13 ml capillary stem volume). The amount of sample poured into the penetrometer was sufficient to achieve 20% stem volume usage, which ensures better resolution of the data. 2. Prior to analysis, the penetrometer containing the sample was degassed under vacuum to a setpoint limit of less than 50 μmHg. The sample was then analyzed in two different operating modes: low pressure (maximum 40 psia, 17 data points) and high pressure (maximum 30000 psia, 32 data points). 3. After completion of the low-pressure analysis, the penetrometer containing Hg and the packed bed is weighed again, and the value is used as software input to determine the bulk density (i.e., the interparticle porosity). 4. Next, the penetrometer was placed in the high-pressure port, and the intraparticle porosity related to the apparent density was measured while applying high pressure. 5. The pore size was calculated using the Washburn equation, assuming a contact angle (θ) of 130 degrees and a value of mercury surface tension (γ) of 0.48 J / m 2 Finally, a summary of the data is displayed by the software of the device.

[0167] Oil number The oil absorption value of the produced gel was measured using the method described in DIN53155 / ISO587 / 5. The oil absorption value is the amount of refined linseed oil required to form a hard paste when a certain weight of pigment is completely wetted and mechanically mixed (i.e., the number of grams of oil required to saturate exactly 100 g of pigment). This value should be considered qualitative and is meaningful in relation to the operation of the preliminary mixer. This value is also used in the calculation of the critical pigment volume concentration. In this case, the measured value is a combination of surface area wetting and penetration of the porous structure.

[0168] Water absorption rate Weigh a small amount (approximately 0.2 grams) of the sample into a small petri dish, place it in a desiccator with blue silica gel at the bottom, and put it in a climate chamber. 1. Usually, the weight loss of the sample is recorded until a stable weight is obtained after 4 - 6 days, and the dry weight is recorded. 2. Put the dried sample into a desiccator (approximately 86% RH) with tap water at the bottom. Usually, the increased weight of the sample is recorded until a stable weight is obtained after 4 - 6 days.

[0169] The increased weight is calculated. This can be expressed as pore volume = (weight of the saturated sample - weight of the dry sample) / density of water. The test is performed in duplicate at 23 ± 2 °C.

[0170] BET BET (Brunauer, Emmett and Teller) analysis measures the specific surface area of a sample, including pore size distribution. The specific surface area of a powder is determined by calculating the physical adsorption of gas onto the surface of the solid and the amount of adsorbed gas corresponding to a monolayer on the surface. Physical adsorption is due to the relatively weak forces (van der Waals forces) between the adsorbed gas molecules and the adsorption surface area of the test powder. The measurement is usually carried out at the temperature of liquid nitrogen. The amount of adsorbed gas can be measured by volumetric measurement or continuous flow method. It should be noted that this method assumes that the gas communicates between the pores and the surrounding volume. In practice, this means that the pores must not be closed cavities. The BET apparatus used in this test: Micromeritics VacPrep or Micromeritics Gemini series equipped with an equivalent drying station. Pore volume > 4×10 -6 cm 3 / g is measured.

[0171] Thermogravimetric (TGA) measurement The sample was analyzed with a Mettler Toledo TGA 40. The sample (usually 10 - 25 mg) was placed in a crucible and weighed. The temperature was raised from room temperature to 800 °C at 10 °C / min. The weight loss was recorded. The solvent usually disappears before reaching 250 °C and usually disappears before reaching 150 °C in relation to gel preparation. Other organic materials containing polymers disappear before reaching 450 °C. Usually only inorganic materials remain at 800 °C. The function control of the apparatus was performed using indium to confirm that the temperature profile was within the calibration values of the apparatus. The weight loss was evaluated using the software program STARe version 7.01.

[0172] Thermal conductivity measurement Test method Complies with ISO 22007-1 (2008): General principles - Line heat source method

[0173] Complies with ASTM D 5930-0: Test Method for Thermal Conductivity of Plastics by the Transient Line Heat Source Method. The measurement is based on a variation of the hot wire method (needle probe method), an unsteady technique that measures the temperature change at a known distance from a line heat source embedded in the test specimen.

[0174] Apparatus Equipped with an ISOMET 2114 Heat Transfer Analyzer - Needle Probe (0.015 - 0.050 [W / m K]). The ISOMET 2114 is a portable hand-held measuring instrument for directly measuring the heat transfer characteristics of various isotropic materials such as foam insulation materials, plastics, liquids, powdered materials, and soil.

[0175] Test Conditions Average measurement temperature of approximately 25 °C. The measurement was carried out in a series of 6 measurements with a 10-minute break between each measurement. The test results are shown in Figure 10.

[0176] Determination of the Hiding Power (Opacity) of Paints and Varnishes Standard: ISO 6504-3:2019 (EN) Determination of hiding power - Part 3: Method C (black and white chart), determination of the contrast ratio of light-colored paints at a constant diffusion rate (ISO 6504-3:2006)

[0177] Apparatus: Color Guide 45 / 0; BYK Gardner Applicator with variable gap Data for black and white chart: 139 × 254 mm - Form 2A - Opacity; The Leneta Company

[0178] Method (Hiding Power): Each sample of the filled aerogel of the present invention was ground in a binder solution and applied at two different layer thicknesses. When comparing different filled aerogels, the concentration of the filled aerogel with respect to the binder was kept constant. After drying, the hiding power was calculated for each chart coated with black (B) and white (W).

[0179] Apply the sample to weighed black / white charts with various film layer thicknesses at 23 ± 2 °C and 50 ± 5% relative humidity. After drying for at least 16 hours, the tristimulus value Y10 can be measured.

[0180] The tristimulus values (three values that are the amounts of three reference colors used together to represent color and can give the same visual sensation as the color considered in combination) of each coated chart are measured at three positions in both the white and black regions of each chart, as well as the average tristimulus values for each of the low coating and high coating.

Number

Number

[0181] Test results The following three paint formulations were prepared.

[0182]

Table 1

[0183] Subsequently, the hiding power of the paint was tested as described above. The test results are shown in the following table.

[0184]

Table 2

[0185] As can be seen from the above test results, all the paints containing the aerogel of the present invention had hiding power, especially with respect to the filled gel.

[0186] Antifouling paint composition The water absorption rate of the coating film is an important parameter related to the leaching layer, leaching of active compounds, erosion rate, and thus antifouling properties. The water absorption rate is affected by the choice of pigment deposition, the selected gel, and the amount of gel. Aerogels are very porous, and it is necessary to achieve equilibrium between various components before performing effective measurements. In the coating composition, it has been shown that the binder system penetrates into the aerogel, reduces the water absorption rate until equilibrium between components is achieved, and ensures that the aerogel particles are firmly fixed in the dried coating layer and are not washed away over time by exposure to water. In the sealant composition, a similar mechanism is considered to be operable. Gels with high intrusion volume values (measured by mercury porosimetry) are assumed to be more easily penetrable by the binder system.

Claims

1. Use of an antifouling additive in a marine paint and coating, said additive comprising: a. an inorganic silica-containing aerogel comprising the following; b. a porous gel lattice, and c. optionally, an alkoxide containing Sc, Ti, V, Cr, Mn, Fe, Co, Y, Zr, Nb, Ru, Hf, Ta, W, Re, Al, Ge, In, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu, and d. one or more biocidal or biorepellent compounds trapped within said aerogel, wherein Here, the silica-containing aerogel contains at least 55% by weight of said one or more biocidal or biorepellent compounds, and here the capture of said one or more biocidal or biorepellent compounds occurs during the sol-gel formation of the gel, and here the one or more biocidal or biorepellent compounds are selected from the group consisting of tolylfluanid, zinc ethylenebisthiocarbamate (= zineb), zinc pyrithione, copper pyrithione, and 2-(p-chlorophenyl)-3-cyano-4-bromo-5-trifluoromethylpyrrole (= Econazole or tralopyril) and mixtures thereof, and here when the aerogel contains up to 75% by weight of Zn pyrithione, the bulk density of the aerogel has a value of up to 0.5 gr / ml, and here the thermal conductivity of the antifouling additive is 0.01 to 0.05 W / m * K, use of said antifouling additive.

2. Use of an antifouling additive in a marine paint and coating according to Claim 1, comprising at least 60% by weight of said one or more biocidal or biorepellent compounds.

3. Use of an antifouling additive in a marine paint and coating according to Claim 1 or 2, comprising at least 75% of said one or more biocidal or biorepellent compounds.

4. Use of an antifouling additive in a marine paint and coating according to any one of Claims 1 to 3, comprising at least 80% of said one or more biocidal or biorepellent compounds.

5. Use of an antifouling additive in a marine paint and coating according to any one of Claims 1 to 4, comprising at least 85% of said one or more biocidal or biorepellent compounds.

6. Use of an antifouling additive in a marine paint and coating according to any one of Claims 1 to 5, wherein said biocidal or biorepellent compound is selected from zinc ethylenebisthiocarbamate (= zineb), zinc pyrithione, copper pyrithione, 2-(p-chlorophenyl)-3-cyano-4-bromo-5-trifluoromethylpyrrole (= Econazole or tralopyril) or a mixture thereof.

7. An antifouling coating composition for protecting the surface of a ship, said antifouling coating composition comprising an antifouling additive comprising: a. an inorganic silica-containing aerogel comprising the following; b. a porous gel lattice, and c. optionally, an alkoxide containing Sc, Ti, V, Cr, Mn, Fe, Co, Y, Zr, Nb, Ru, Hf, Ta, W, Re, Al, Ge, In, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu, and d. one or more biocidal or biorepellent compounds trapped within said aerogel, wherein Here, the silica-containing aerogel contains at least 55% by weight of the one or more biocidal or biorepellent compounds, and here the capture of the one or more biocidal or biorepellent compounds occurs during the sol-gel formation of the gel, and here the one or more biocidal or biorepellent compounds are selected from the group consisting of tolylfluanid, zinc ethylenebisthiocarbamate (= zineb), zinc pyrithione, copper pyrithione, and 2-(p-chlorophenyl)-3-cyano-4-bromo-5-trifluoromethylpyrrole (= Econazole or tralopyril) and mixtures thereof, and here when the aerogel contains up to 75% by weight of zinc pyrithione, the bulk density of the aerogel has a value of up to 0.5 gr / ml, and here the thermal conductivity of the antifouling additive is 0.01 to 0.05 W / m * K, the antifouling coating composition.

8. The antifouling coating composition according to claim 7, comprising at least 6% by weight of one or more biocidal or biorepellent compounds selected from the group consisting of zinc ethylenebisthiocarbamate (= zineb), zinc pyrithione, copper pyrithione, 2-(p-chlorophenyl)-3-cyano-4-bromo-5-trifluoromethylpyrrole (= Econazole or tralopyril), or mixtures thereof.

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