LT6741B - Biocidal roofing granules and methods for production thereof - Google Patents

Abstract

This invention relates to biocidal roofing granules intended for coating bitumen-polymer roofing materials, in particular shingles, to prevent algae and fungi infestation and growth. Biocidal roofing granules contain a crushed mineral base and are coated with one, two or more ceramized layers of kaolin, liquid glass and a biocide. A biocide used in the coating is a brass powder of a copper-zinc alloy with particle size in the range of 5 to 75 µm and the zinc content of 15 wt % to 30 wt %, wherein the amount of the biocide in the coating is in the range of 4.5 kg to 60 kg per ton of the base material.

Description

Technical field

The present invention relates to the production of biocidal roofing granules based on rock. The invention can be used to protect roof and facade materials, including bitumen-polymer based materials, especially shingles, from various types of biological growth.

State of the art

Roofing pellets, both natural and artificially coated in color with valuable properties, are important for the functional resistance of roofing.

Roofing granules are widely used for the protection of roofing (decking), which is made of bituminous or bituminous-polymeric materials, or any other decking, such as composite tiles, against various mechanical damages, ultraviolet radiation, which accelerates the aging of the bituminous decking. perforation of the roof covering and damage to its waterproofing properties. Roofing granules also increase the antipyretic properties of the roof.

Dark spots or streaks are known to appear on the roof surface, such as on shingles, especially in warm and humid climates. These stains are usually caused by algal colonies or other various microbiological and plant formations growing on the surface, such as fungi, moss, lichens or bacteria, which occur under certain conditions, such as on wood shingles and / or in constantly humid areas. . The first signs of biological growth can occur already in the second year of roof operation.

The main species of algae that grow on the surface of shingles are cyanobacteria (cyanobacteria) of the genus Gloeocapsa, especially Gloeocapsa Magma. The stains formed by these fast-growing algae gradually turn into ugly faded strips as precipitation washes the layers down from the roof. In severe cases, this fading can eventually spread throughout the roof.

In addition to the deteriorating appearance, fading can cause the roof to overheat; abundant biological derivatives can physically break down ceramic tiles as they grow between shingles. Finally, all of these factors lead to fading and malfunction of the roofing material.

There are different methods commonly used to prevent biological growth. For example, biological growth products can be washed with water with various surfactants using pressure in or without pressure. Such a cleaning process is quite expensive and should be repeated every 2-3 years. In addition, mechanical action can damage the integrity of the protective layer, which will result in the destruction of the roofing material in a short time. Active detergent chemicals may contain substances that adversely affect the adhesion of the granules to the bitumen base and reduce the integrity of the ceramic layer.

The roof can be sprayed with different oxidizers such as bleach. However, with frequent use of this method, the pellets can lose adhesion to the bitumen base, and cause the roofing to decompose. In addition, the use of biologically active materials for the roof is usually effective for less than two years after cleaning.

Another more effective approach involves the use of biocidal roofing granules as a bituminous roofing material, such as shingles, in particular to prevent various microbiological and plant formations and fading algae.

Many chemicals called biocides are used to prevent biological growth on the roof. The name 'biocides' is derived from the Greek word bias, which means life, and from the Latin caedo, which means killing, and is a substance that kills harmful organisms, including pesticides (bactericides, fungicides, insecticides, herbicides, zoocides, etc.), antiseptics, disinfectants measures and preservatives used for the control of organisms harmful to human or animal health which may harm natural or industrial products (http://www.xumuk.ru/encvklopedia/572.html).

The best known biocides are metals and their oxides, such as copper oxide, both alone and in combination with zinc oxide, zinc powder, and the like. Typically, these biocides are effective for about ten years, in some cases fifteen years, while the service life of the roofing material is much longer than ten to fifteen years and depends on the type of shingles and the construction of the roof.

Roofing granules containing biocides, including fungicides, algicides and other components, provide protection against different types of biological growth on the roof or façade, especially on shingles.

Due to the high content of copper and zinc ions, granules containing copper and zinc oxides are used as biocides at a rate of 10% of the total weight of the shale granule. They are believed to provide a result that is sufficient to prevent biological growth on the roofing. In rain, copper and zinc ions are leached from biocidal granules that are evenly distributed on the roof surface, thus protecting the roof from biological growth.

When the ratio of biocidal beads to conventional (i.e., non-biocidal beads) is 10:90, it is assumed that each biocidal bead produces active metal ions that protect 9 conventional beads. For this coating to be effective, the biocidal granules must be evenly distributed among the conventional granules and the roof surface must be richly moistened with heavy rainfall to ensure proper distribution of active ions among the conventional granules.

In general, biocidal granules high in copper and zinc oxides are dark in color and contain between 30 and 60 kg of oxides per tonne of finished granules. To produce beads of a color different from that of copper oxide, copper oxide should be incorporated into the composition of the inner ceramic shell of the bead and the desired color provided by the outer shell. In this case, the outer shell serves as a barrier to copper ions, and prevents it from entering the surface of the bead.

The following are known examples of biocidal roofing granules of the present invention.

Published U.S. Patent Application No. 3507676 (1970) describes a granular coating comprising a zinc algicide for roofing granules to protect roofing from algal invasion. The algicide incorporated in the coating is in the form of metallic zinc, ZnO and / or ZnS.

The imparting of alicidal properties to roofing granules by the incorporation of metal algicides in the treatment of oil commonly used for the treatment of roofing granules coated with such a color is described in published U.S. Pat. 3888176 (1975). The application discloses many metal algicidal compounds that could be used, preferably copper algicides. Metal algicides adhere to the surface of the colored coating of the granules, and their finer particles are adsorbed into the colored layer with the treatment oil. The use of copper (copper metal powder) and zinc (zinc compounds) algicides produces toxic bimetallic effects that are particularly effective in slowing the growth of algae and / or fungi.

Biocidal shingles are disclosed in published U.S. Application No. No. 5356664 (1994), which describes a mixture of copper-containing algae-resistant granules and algae-resistant granules. Copper-containing algae-resistant granules have an inner ceramic coating consisting of copper oxide and a copper-free sealing coating.

U.S. Pat. U.S. Patent No. 6,214,466 (2001) discloses algae-resistant roofing granules coated with a first layer of a calcined silicate-clay matrix containing copper oxide and zinc sulfide to achieve slow, long-term release of bimetallic copper and zinc ions; and a second layer consisting of a fired silicate-clay matrix containing a dye.

Algae-resistant roofing pellets are disclosed in Published U.S. Application No. 2004139886 (2004), consists of one or two layers of fired semi-ceramic compositions containing a metallic copper powder that do not significantly affect the color tone of the coating dye. This description can be considered as the closest analogue of the technical solution of the present invention. The object of the invention according to this description is to enhance the algicidal activity of artificially painted roofing granules containing algicides. Disclosed here is a unique metallic copper powder composed of irregularly shaped particles formed during the copper spraying / oxidation and copper oxide / hydrogen reduction processes. The process produces irregularly shaped, highly textured, sponge-shaped copper metal aggregates with a particle size of 575 microns.

Thus, technical solutions known in the art include granules in which copper oxide (alone or in combination with a zinc compound) is embedded in some semi-ceramic coatings with an encapsulated crushed rock base. Granules are also known which have at least two and sometimes even three ceramic coatings in which copper and zinc compounds are incorporated in the inner coating and inorganic dyes which determine the overall color of the product are incorporated in the outer coatings. These products are designed to be mixed with conventional granules in an amount of 10-15% and are designed to ensure the continuous release of algicidal copper / zinc ions in the presence of moisture due to rain and dew. However, despite the high copper / zinc content of the granules, the rate of ion release is often insufficient due to the low porosity of the outer coating, which impedes the migration of copper / zinc ions. This can lead to early destruction of biocidal roofing granules and improper discoloration of the roof.

In addition, when biocides such as copper and zinc are incorporated into the granular composition, individually and in powder form, the zinc component is first dissolved, while the dissolution of copper is delayed. In this case, the required concentration of copper ions cannot be achieved to prevent bacterial growth. In addition, the inadequacy of copper-containing paints due to the formation of a passivation layer on the surface of copper-containing particles occurs (Failure Mechanism of Copper Antifouling Coatings, Elek Linder, pp. 247-253, 1988 International Biodeterioration, vol. 24 (4-5), p. 247-253). The passivation layer reduces and even eliminates the activity of copper as a biocide in the granule composition.

Published U.S. Application No. 2004139886 (considered a prototype) states that a unique metallic copper powder with a particularly high specific surface that is produced in a special way must be used. The use of copper particles with a particularly high specific surface allows to achieve only the desired dissolution rate of metallic copper and not of copper oxides. However, the production process of unique metallic copper powders with a highly developed surface is inefficient because it is exploited in pellets according to a prototype and the powder itself is not a commercially available product.

Thus, there is a constant need for biodegradable roofing materials with a certain algicide release property, which allows the roofing material to be adapted to site-specific conditions. In addition, there is a constant demand for biodegradable and long-lasting roofing materials.

The essence of the invention

The technical problem of the invention is solved by the production method of biocidal roofing granules with a high release rate of biocidal ions in order to control (prevent or inhibit) biological growth in the long run. The pellets should contain commercially available components and should be manufactured in a cost-effective manner.

The technical effect of the invention is improved by the product, i. y. pellets, including appropriate economical production using commercially available raw materials. When small amounts of biocides are used, i.e. in the range of 4.5 kg to 8 kg per tonne of crushed mineral base, there is no need to ensure an even distribution of biocide granules between conventional granules and abundantly moistened roof surfaces with intense precipitation to distribute active ions between conventional granules, and it would continue to be possible to successfully exploit the granules on the roof surface. By omitting this step of the manufacturing process according to the present invention, it is possible to reduce the operating costs of the biocidal granules.

In order to achieve the above-mentioned technical effect, a first embodiment of the present invention provides biocidal roofing granules consisting of crushed rock-based minerals; at least one ceramic coating layer comprising kaolin, liquid glass and a biocide, wherein the biocide comprises a brass powder which is a copper-zinc alloy with a particle size in the range of 5 to 75 μm and a zinc content in the range of 15% by weight to 30% by weight, where the biocidal product is in the range of 4,5 to 30 kg per tonne of base material.

Biocidal roofing granules may contain between 4.5 kg and 8 kg of biocide per tonne of base material.

Biocidal roofing pellets may contain 30 kg of biocide per tonne of base material.

Biocidal roofing granules containing 30 kg of biocide may be mixed with biocide-free granules (non-biocidal) in a ratio of 20 biocidal granules to 80 non-biocidal granules.

According to another aspect of the invention, there is provided a method of making biocidal roofing granules comprising the steps of:

grinding and particle size distribution of mineral material;

preheating of crushed and sized minerals;

coating the preheated comminuted and particle sized mineral material with a composition comprising kaolin, liquid glass and a biocide to form granules; and firing the granules to form a ceramicized coating layer thereon.

The method of making biocidal roofing granules may also comprise the steps of: coating the surface of the granules with a painting composition comprising kaolin, liquid glass, a dye or a mixture of dyes and a dispersant to paint the granules; and burning the painted granules.

The method of making biocidal roofing pellets may also comprise the post-treatment step of coating the surface of the pellets with a post-treatment composition comprising latex or an industrial oil and water repellent.

According to another embodiment of the invention, biocidal roofing granules are provided having at least two coating layers comprising:

crushed rock-based material;

a first inner layer of ceramic coating; and a second outer layer of ceramic coating, wherein both the outer and inner layers comprise kaolin, liquid glass, and a biocide, wherein the biocide comprises a brass powder which is a copper-zinc alloy having a particle size in the range of 5 to 75 and a zinc content of in the range of 15 to 30% by weight, where the total content of the biocidal product in both the inner and outer layers of the granules exceeds 30 kg but does not exceed 60 kg per tonne of base material.

Biocidal roofing pellets may contain 60 kg of biocide per tonne of base material.

Biocidal roofing granules containing 60 kg of biocide per tonne of base material may be mixed with non-biocidal granules in a ratio of 10 biocidal granules to 90 non-biocidal granules.

The biocidal roofing granules having one or two coating layers may further comprise a dye or mixture of dyes and a dispersing agent in the outer ceramicized coating layer.

Biocidal roofing beads having one or two coating layers may further comprise an additional outer layer of ceramicized kaolin, liquid glass, dye or mixture of dyes and a dispersing agent to coat the surface of the beads.

The surface of the biocidal roofing granules having one or two coating layers may be further coated with a post-treatment composition comprising latex or industrial oils and a water-repellent material.

The post-treatment composition of the biocidal roofing granules may also contain an organic biocidal component.

According to another aspect of the invention, there is provided a method of making biocidal roofing granules with a bilayer coating, comprising the steps of:

grinding and particle size distribution of mineral material;

preheating of crushed and particle-sized mineral material;

coating the preheated comminuted and particle sized mineral material with a composition comprising kaolin, liquid glass and a biocide to form granules;

firing the granules to form a ceramicized coating layer thereon;

cooling the burnt pellets to a temperature of about 80 ° C by air flow and / or water;

heating of coated granules;

coating the fired granules with a second composition comprising kaolin, liquid glass and a biocide to form a second coating layer on the granules; and firing the granules to form a ceramicized second coating layer thereon.

Brief description of the drawings fig. shows a corrosion image of brass (70% Cu, 30% Zn) forming a porous structure. The surface image was taken using a REMMA-202M scanning electron microscope.

Methods of realization of the invention

Roofing granules are usually placed on the surface of bituminous-polymeric roofing materials, and they form a coating responsible for the environmental resistance of the roof surface. Granular coating, in addition to its undoubted usefulness, also provides aesthetic appeal; therefore, mineral granules are usually covered with a colored coating to enhance the visual decorative effect.

Typically, roofing granules are made up of particles that have been previously crushed and sized, and which are then coated with a ceramic veneer (coating layer) with certain pigments or dyes (depending on the desired roof color), which are usually a variety of metals. oxides.

The granules are mixed with a dye using a solution of a soluble silicate binder which, after heat treatment, enters a water-insoluble state, as in the case of a silicate / clay coating matrix, or a combination of heat treatment and chemical treatment, for example by adding acidic substances to soluble silicate. . The function of the soluble silicate is first to distribute the dye evenly and to incorporate the dye into the coating matrix, and then to bind the dye to the granules when the silicate becomes insoluble. Binders can be any suitable material for this purpose, such as alkali metal silicates, such as potassium or sodium silicates.

The ceramic shell is made of a solution containing kaolin, a dye, and sodium in liquid form, which is an aqueous solution of sodium silicate. A typical paint composition forming a ceramic layer comprises 25% liquid glass, 21% kaolin, 14% colorant, and 40% water. Upon heating, sodium ions are released from the liquid glass, and aluminum is released from the kaolinite, resulting in a new crystalline phase derivative of mica. Combustion produces mineral particles covered with a colored insoluble coating.

The most common process for the production of biocidal granules consists of two stages. In the first step, metal oxides such as copper oxide and / or zinc oxide are added to the liquid glass and kaolin solution. This solution is used to fill mineral rock, which is pre-crushed and heated. Later, during firing, the coating is heated to 500 ° C, which determines the insolubility of the coating. In the second step, the granules are coated with a coloring solution containing a mixture of dyes required to paint the biocidal granules with the desired color. The resulting biocidal granules, alone or in a mixture with conventional granules, are used in the production of roofing materials, in particular shingles, in accordance with the process regulation. The biocidal granules according to the present invention protect the roof, in particular shingles, from biological growth.

Selective corrosion of copper-zinc brass is known in the state of the art (IK Marshakov, AV Vvedensky, V.Yu. Kondrashin, GA Bokov. Anodic dissolution and selective corrosion of alloys. Monograph. Voronezh: Publishing House of the Voronezh State University, 1988, 208 p. G. Keshe Corrosion of metals Physicochemical principles and current problems Metallurgiya, 1984. 400 p. RS Luchkin Corrosion and protection of metallic materials (structural and chemical factors): electronic training book / Tolyatti: Publishing House of the Tolyatti State University, 2017, p. 239). In particular, the brass disinfection process takes place in brass containing less than 85% copper and where the alloy does not contain impurities that inhibit the release of zinc, such as arsenic, phosphorus or antimony. The essence of this phenomenon is that the electrochemical properties of brass components such as copper and zinc are very different. Therefore, zinc (having a lower electrode potential) is selectively dissolved first, and then a surface layer enriched with copper is formed. As soon as this occurs, the electrode potential of the brass shifts in the positive direction as much as it is still possible to dissolve the copper component. From this moment on, the melting of the brass takes place evenly, i. i.e., the process proceeds in the same ratio, ionizing zinc and copper, as would occur if they were in the alloy. The result of the electrochemical disinfection process is the dissolution of zinc, in addition to which it causes the formation of a porous zinc-free mass of copper with weak mechanical properties. This mass decomposes rapidly, resulting in significant contamination of the copper surface and, in some cases, the formation of holes.

Therefore, the almost pure copper surface created during selective corrosion is formed due to the leaching of zinc ions from the surface (see Fig. 1), which accelerates its dissolution and prevents the formation of a passivation layer on the surface.

Unexpectedly, it has been found in the present invention that the above effect, which is detrimental to the consumption of brass products, can play a positive role in the use of brass in the composition of roofing granules. According to the present invention, it has been demonstrated that the addition of finely dispersed copper-zinc brass powder as a biocide to a layer of ceramic roofing granules enables the production of granules with good biocidal properties which persist for a long time.

Moreover, in this case, the zinc component does not reduce the dissolution rate of copper, but significantly increases it, which allows the synergistic effect of copper and zinc ions to be exploited for the growth of bluetongue.

The present invention provides biocidal granules which, unlike the prototype, use only commercially available products, especially copper-zinc alloys, such as STANDART Lack L 900 Rich Gold Bronze Powder (70% Cu, 30% Zn) or STANDART Lac L 900 Rich Pale. Gold Bronze Powder (85% Cu, 15% Zn) with an average particle size of 32.0 to 38.0 pm. These types of copper-zinc alloys are only examples and should not be limited. According to the present invention, any brass powder having the above characteristics can be used as a variocin alloy.

The following main raw materials can be used for the production of biocidal roofing granules according to the technical solution of the present invention:

a. rock stone as a mineral base;

b. liquid sodium glass;

c. kaolin;

d. optionally, dyes;

a. Examples of rock types suitable for the production of roofing granules:

basalts;

andesites;

diabetes;

nepheline syenites;

tuffs and porphyrites.

Main properties of minerals:

ability to completely block UV radiation;

chemical and physical inertness sufficient:

a. resistance to acid rain;

b. salt fading;

c. resistance to freezing / thawing cycles;

d. resistance to moisture / drought cycles;

e. rust resistance;

low porosity, which gives:

a. sufficient strength;

b. adhesion of ceramic shell and stone;

c. optimal paint consumption to create the desired coating;

resistance to extremely high temperatures;

hardness required:

a. overcome resistance during painting;

b. degradation resistance during transport and when working with shingles;

di delis density so that the shingles carry sufficient weight to protect against wind force and to remain adhered throughout the life cycle of the shingles;

optimal cubic shape by crushing to ensure even application of the granules, coating and subsequent absence of gloss on the roof due to improper orientation of the granules.

b. Liquid sodium glass:

Liquid sodium glass is an aqueous solution of sodium silicate.

Liquid glass having the following characteristics can be used to produce ceramic roofing granules:

table. Characteristics of liquid sodium glass

SiO ₂ : Na ₂ O ratio ± 0.05 Na ₂ O content,% ± 0,2 SiO2 content,% ± 1.0 Amount of impurities,% ± 0.05 Density, g / cm 2 Viscosity, cPs 2.88 11.00 31.70 0.50 1.48 960.00

c. Kaolin

The main component of kaolin is the mineral kaolinite, which is a product of the natural destruction of feldspar. Chemically, kaolinite is a hydrated compound of alumina Al2O3 with silica SiO ₂ . Kaolin, like any clay, has a variety of impurities that affect its color. Kaolin is widely used in silicate paints. It is used as a filler, diluent, solubilizer or adsorbent and a reagent that determines the insolubility of the ceramic coating of roofing granules after firing.

d. Dyes (pigments)

Inorganic temperature-resistant pigments such as carbon black (technical carbon), titanium dioxide, chromium oxide, yellow iron oxide, ultramarine blue, red iron oxide, metal ferrite, etc., as well as mixtures thereof, can be used for the production of ceramic roofing granules.

According to the present invention, the granules are coated with at least one or two ceramic layers. The ceramic layer contains from about 3 kg to about 30 kg of biocide per ton of substrate, preferably from about 4.5 kg to about 8 kg of biocide per ton of substrate, or 30 kg of biocide where the biocide is a fine brass powder with particle sizes from 5 to 75 pm, where the zinc content is from about 15% to about 40% by weight, more preferably up to about 30% by weight.

The granules of the present invention may also have a second ceramic layer that is applied to the first ceramic layer. The second ceramic layer may optionally contain a biocide and optionally may contain a dye.

If the second ceramicized layer does not contain a biocide, then this layer serves to slow down the diffusion of copper ions to the surfaces, and thus ensures a longer biocidal activity of the granules. In addition, due to the fact that the outer layer of the granules does not contain biocidal powder but contains a colorant, the granules can be painted in colors that correspond to the colors of standard non-biocidal granules, which significantly expands their scope.

According to the present invention, the brass powder must be comminuted to a micron-sized size, i. i.e. their particle size must not be larger than the particles of other dyes due to the particles not settling in the paint, i. i.e., they must be between 5 and 75 μm in size and the surface of their particles must be treated, which is necessary to ensure the biocidal effect of the granules.

According to the present invention, the content of zinc in the copper-zinc (brass powder) alloy is from 15% by weight to 40% by weight, preferably up to 30% by weight.

The zinc content of said alloy should be about 15% by weight, since the effect of selective corrosion (brass decinking) begins to occur when the copper content of the brass is less than or equal to about 85%, i. i.e. in a two-component, copper-zinc system with a zinc content of about 15% or more (RS Luchkin. Corrosion and protection of metallic materials (structural and chemical factors): electronic training book / Tolyatti: Publishing House of the Tolyatti State University, 2017, p. 239).

However, an excessive increase in the zinc content of the alloy reduces the total amount of the parent biocide, which is copper, which can potentially be released, and this can negatively affect the effectiveness of the biocidal properties of the granules. Therefore, the zinc content of the brass powder is between 15 and 40% by weight, preferably between 15 and 30% by weight, and this can be considered as a reasonable recommended limit.

The present invention describes several different types of biocidal granules for various uses:

(1) biocidal granules for use without mixing (without mixing) with conventional granules without biocide;

2) biocidal granules for use mixed with conventional granules.

In the case of biocidal granules used without mixing, the amount of brass powder in the granules is from about 3 kg to about 10 kg per ton of base material, preferably from about 4.5 kg to about 8 kg per ton of base material.

As it turned out during the experiment, the amount of brass powder in the granules from 4.5 kg to 8 kg per tonne is optimal. A lower amount of powder does not sufficiently protect the roof from biological growth; however, the use of a higher quantity is not justified for economic reasons.

With such a relatively small amount of brass powder sufficient to protect the biocidal granules themselves from biological growth, the ceramic coating can be easily painted in any color or left unpainted, the natural color of the mineral-based material.

In addition, the use of biocidal granules in this case does not require mixing with conventional granules, which reduces the production costs of the final product, ready-to-use biocidal granules.

In the case of the use of biocidal granules, when mixed, the amount of brass powder in the granules is higher than 10 kg per tonne of mineral base, as the biocidal granules are used mixed with conventional granules.

According to the present invention, the biocidal granules are provided for use with the following mixing ratio:

a) 20:80, t. i.e. a mixture containing 20 kg of biocidal granules and 80 kg of conventional granules, wherein the amount of brass powder in the biocidal granules is equal to about 30 kg per tonne of mineral base;

b) 10:90, t. i.e. a mixture of 10 kg of biocidal granules and 90 kg of conventional granules, where the amount of brass powder in the biocidal granules is equal to about 60 kg per tonne of base.

It is technically difficult to add more than 30 kg / t of brass powder to one coating layer, in the latter case two ceramic coatings are applied, each containing about 30 kg / t of brass. Two layers of ceramicized beads, each containing a biocide, may be coated with a third layer of ceramicized, free of biocide, to impart the desired color to the beads.

The stated amounts of biocides in biocidal granules are not restrictive, as granules with different amounts of biocidal product can be produced within a specified range, if necessary, for use with or without mixing.

The brass powder used has a significantly lower dyeing capacity than copper oxide, which reduces the cost of obtaining the desired color using mineral dyes.

Disintegrants are added to the shell to ensure the migration of copper ions through the outer shell, which is formed by successively ceramicized layers without biocide. Any material suitable for such purposes can be used as a disintegrant, such as mixtures of sodium perborate tetrahydrate and boric acid, sodium azide (NaN ₃ ) or sodium borohydride (NaBH ₄ ). These examples also do not limit the selection of suitable disintegrants for this purpose.

The method of producing biocidal roofing granules according to the present invention is as follows: the pre-crushed rocks to the required size undergo further steps of preheating in a tumble drying. For this purpose, the smooth flow of the mineral rock base (rock) fraction from the storage hopper to the drying drum is transferred by a loading conveyor, while heating at an internal temperature of 200-230 ° C. During feeding, the granules are heated to 120 ° C. From the drying drum, the unpainted granules are transferred by a bucket elevator to an intermediate hopper so that they can later be discharged into a rotary mixer by a loading conveyor.

Further, the granules are a coating composition (solution) comprising kaolin as a mineral filler, liquid glass, brass powder, water and, optionally, a dye or mixture of dyes and a dispersing agent. The granules are then fired to form at least one ceramic layer on their surface.

In case dyes are used in the granule coating composition to obtain the desired color, some dispersing agents should be used to distribute the dye (dye mixture) in the composition (dye solution). Any material suitable for this purpose can be used as dispersing agents, including lignosulfonate, aqueous polymer dispersions such as sodium polyacrylate, and the like. Lignosulfonate is a by-product of wood processing. Technical lignosulphonates are a mixture of lignosulphonic acid salts (with mixed reducing and mineral substances) obtained from bisulphite cellulose cooking waste liquids. The selection of suitable dispersing agents for this purpose is not limited to the examples provided.

The composition for subsequent formation of the ceramic layer on the surface of the granules is separately prepared in a vertical mixer equipped with a high-speed mixing device to improve its dispersion. The components are delivered to the mixer in the following order:

1. half the amount of water required;

2. Liquid sodium glass;

3. remaining water;

4. kaolin;

stirring for 15-20 min.

5. biocide and / or dye (optional);

6. dispersing agent (if a dye is used);

mixing for 30 minutes (if dye and dispersing agent are used).

The components of the composition for forming the ceramic layer are distributed using tensiometers mounted on the bottom of a vertical mixer. Dosing of small amounts of components is done manually.

In the case where a dye is used to color the granules in a desired color, a sample of the composition is taken by mixing the colorant of the mixture with a dispersing agent and checking that the granules correspond to the desired color. If the composition sample coincides with the reference sample, the solution is pumped into a supply tank which is raised to the level of a rotary drum mixer.

When changing colors, the staining solution preparation system (i.e., a composition comprising a dye or a mixture of dyes and a dispersing agent) must be washed. The vertical mixer and supply tank are washed with hot water using a special flushing device with rotating nozzles. Dirty water is cleaned after washing the paint containers by passing it through large and fine filters, and can then be reused to prepare black and gray paint.

The application of the composition to the process of preparing the ceramic layer begins with feeding the granules preheated to 100-120 ° C together with the composition, including the paint composition, into a drum mixer in a certain volume. The pellets move along the mixer, tilting the drum 4 ° in the direction of material movement.

A paint composition (solution) is a mixture of kaolin (a mineral filler), a liquid glass, a dye or a mixture of dyes and a dispersing agent. The color intensity is determined by the ratio of the flow rate of the dye solution to the amount of stone added to the mixer.

Spatulas of different configurations are installed along the entire length of the mixer to ensure proper mixing of the granules with the composition to be used. In case the temperature of the incoming granules and the distribution of the composition in the ceramic layer containing the painting solution are controlled correctly, granules with a well-distributed coating composition, including well-colored granules with a painting quality of more than 70% of the coating, are obtained at the mixer outlet. .

The pellets coated with the composition are burned in a combustion furnace using a countercurrent heat flow where the heat exchanger temperature is about 900

980 ° C. The spatulas on the inner walls digest the pellets as they move along the kiln to ensure maximum possible contact with hot air. The movement of the material is ensured by tilting the drum in the direction of movement 4 °. The efficiency of the process is determined by the speed of rotation of the drum. In terms of process implementation, the furnace is designed to heat roofing pellets with a bulk density of 1400-1700 kg / m ³ , taking into account that heating from 50 ° C to a maximum temperature of 550 ° C using natural gas.

The pellets then enter the cooler immediately after cooling, where they must cool. The pellets are used in a cooler by tilting the drum at an angle of 4 ° in the direction of material movement. Performance is determined by the speed of rotation of the drum.

In terms of process implementation, the cooler is designed to cool roofing pellets having a bulk density of 1400-1700 kg / m ³ , depending on the fact that it is heated from a temperature of about 550 ° C to about 80 ° C. Inside the drum, cooling takes place due to the evaporation of the water supplied to the cooler and the air flow generated by the fan.

The cooled and cleaned pellets are then transferred to another treatment plant where the pellets, whether colored or unpainted, are reprocessed to control dust and improve pellet adhesion, waterproofing properties and, optionally, biocidal activity of the roofing pellets during the early life. until an effective concentration of copper and zinc ions in the immediate vicinity of the granules can be reached.

Various materials such as latex or various industrial oils are used to prevent dust from accumulating on the granules during transport. Any suitable latex commonly used in the manufacture of roofing granules can be used for this purpose, such as poly (meth) acrylate products, including aqueous dispersions of polymethyl methacrylate, copolymers of methyl methacrylate and alkyl acrylates such as ethyl acrylate and butyl acrylate, and acrylate and methacrylate and methacrylate copolymers of monomers with other monomers such as styrene. One such suitable latex is, for example, Acronal latex, such as Acronal A754, a copolymer of acrylic and methacrylic acid esters. Any industrial oil, such as Class I-20A, can also be used.

According to the present invention, water-repellent materials are used to improve the adhesion of the granules to the substrate and their waterproofing properties, which can be any acceptable water-repellent materials, such as various silicone emulsions, etc., including Silres emulsions such as Silres 5137. . It should go without saying that these examples are not restrictive.

In the granule post-treatment step, an organic biocidal component is optionally used, which, if used, first extends the biocidal activity of the granules and secondly gives the roofing granules biocidal activity in the early life, when the effective concentration of copper and zinc ions in the granules cannot be reached. in the immediate environment.

The following compounds can be used as organic biocidal components: hexahydro-1,3,5-tris (2-hydroxyethyl) -S-triazine, hexahydro-1,3,5-triethyl-triazine, 2- (tert-butylamino) -4- chloro-6- (ethylamino) -S-triazine, tetrahydro-3,5-dimethyl-2H-1,3,5-thiadiazine-2-thione, 3-iodo-2-propylbutylcarbamate, sodium dimethyldithiocarbamate, disodium dienyl dicarbonate, disodium cyanothioimidocarbamate, methyldithiocarbamate, potassium dimethyldithiocarbamate, 2,2-dibromo-3-nitripropionamide, 2,2-dibromo-2-nitroethanol, 2-bromo-2-nitro-1,3-propanediol, 4,5-dichloro-2-n-octyl-4 -isothiazolin-3-one, 2-methyl-2,3-dihydroisothiazol-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, 2-noctyl-4-isothiazolin-3-one, chlorallyl- 3,5,7-Ozone adamantane chloride, tetrakium hydroxymethylphosphonium sulphate, poly (oxyethylene (dimethylimino) ethylene (dimethylimino) ethylene dichloride, didecyldimethyl ammonium chloride and dodecyl guanidine hydrochloride or other conventional organic biocide.

However, the materials listed above are easily washed off the surface of the granules (usually within one year). Therefore, as a more suitable alternative, ionic positively charged polymers having a quarterly nitrogen atom can be used, especially poly-N-ethyl-4-vinylpyridine bromide, polydimethyldiallylammonium chloride, polymers based on epichlorohydrin and dimethylamine, and their interpolielelectrolide complexes with anionic polymers and anionic polymers. active substances. Such complexes are strongly attached to the surface of the granules and therefore ensure the long-term biocidal activity of the granules. In addition to the biocidal activity of copper and zinc ions, they provide protection of the granules against many species of microorganisms for a longer period of time (up to 10 years). It should be understood that the examples of components listed above are also not limiting.

The after-treatment unit consists of a storage tank, a loading conveyor, a two-shaft mixer, a drying drum and a cooling drum. The twin-shaft mixer is used to distribute the latex or industrial oil solution, the water-repellent material and, optionally, the organic biocidal component on the coated biocidal granules.

The latex or industrial oil composition with the water-repellent material and, optionally, with the organic biocidal component is prepared in a separate tank and then transferred to a mixer by means of a metering pump.

In the case of industrial oil, no drying of the granules is required.

If latex is used instead of industrial oil in the post-treatment step, the granules with the composition used in this step are dried at a temperature of about 120 ° C in a drying drum with simultaneous heating. After drying, the prepared granules have a temperature of 110-120 ° C, so they need to be cooled to avoid problems when packing in plastic bags. The pellets are passed through a cooling drum and fed to a filling unit or storage hopper to cool to about 70 ° C.

The invention will not be illustrated by the following examples alone.

example table. Naturally painted single-layer biocidal roofing granules (used without mixing)

Ceramic layer composition g Mineral granules 1000 water 13 liquid sodium glass 20 kaolin 13 STANDARD Lac L 900 Rich Gold Bronze Powder (70% Cu, 30% Zn) 4.5 Composition after further processing

Granules with a ceramic coating 1000 industrial oil 3 SILRES® BS 290 0.2

To obtain a ceramic layer, 1000 g of unpainted granules are heated to about 120 ° C and coated with a composition consisting of previously mixed 13 g of water, 20 g of sodium glass in liquid form, 13 g of kaolin and 4.5 g of STANDART Lac L 900 Rich Gold Bronze Powder powders containing 70% Cu and 30% Zn. The resulting granules were burned at 500 ° C for 20 minutes, then cooled to 80 ° C. The ceramicized granules obtained during the additional treatment step are coated with a solution of 3 g of industrial oil and 0.2 g of water-repellent SILRES® BS. In this case, drying is not required.

example table. Red single layer biocidal roofing granules (used without mixing)

Ceramic layer composition g Mineral granules 1000 water 13 TEGO® Dispers 715 W (dispersing agent) 0.3 liquid sodium glass 20 kaolin 13 red iron oxide dye 8 STANDART Lac L 900 Rich Pale Gold Bronze Powder (85% Cu, 15% Zn) 8 Post-treatment composition The granules are coated with a ceramic layer 1000

water 5 Acronal A754 2 Silres 5137 0.5 “Narat Polyelectrolyte Complex (TU 2499-004-81049258-2016) 0.3

The granules are prepared according to the method described in Example 1. In addition, TEGO® Dispers 715 W dispersing agent is included in the composition, Acronal A754 latex is used instead of industrial oil in the post-treatment step, and water with an organic biocidal component is additionally included in the composition. (Narat Polyelectrolyte Complex).

example table. Black two-layer biocidal roofing granules (mixture of 20% biocidal granules + 80% non-biocidal granules)

Composition of the first ceramic layer g Mineral granules 1000 water 15 lignosulfonate 0.2 liquid sodium glass 24 kaolin 15 red iron oxide dye 0.4 technical coal 1 STANDARD Lac L 900 Rich Gold Bronze Powder (70% Cu, 30% Zn) 30 Composition of the second ceramic layer

The granules are coated with a first layer 1000 water 13 sodium perborate tetrahydrate 0.4 boric acid 0.4 lignosulfonate 0.2 liquid sodium glass 20 kaolin 13 red iron oxide dye 0.35 technical coal 0.9 Post-treatment composition The granules are coated with a second layer 1000 water 5 Acronal A754 2 Silres5137 0.5

As in the first layer, 1000 g of unpainted granules are heated to 120 ° C and coated with a pre-prepared composition consisting of water, lignosulphonate, soda glass, kaolin, red iron oxide dye, technical carbon and brass powder, where the amounts of the components are given. In Table 2. The resulting granules are fired for 20 minutes at a temperature of about 500 ° C, then cooled to 80 ° C.

To coat the granules with the second coating layer, they are reheated to about 120 ° C and coated with a pre-prepared mixture of water, liquid sodium glass, kaolin, sodium perborate tetrahydrate, boric acid, red iron oxide dye and technical carbon composition. The resulting granules are fired for 20 minutes at about 500 ° C and then cooled to about 80 ° C.

In the further processing step, the ceramicized granules are coated with a composition consisting of water, Acronal A754 and Silres 5137. The obtained granules are dried at a temperature of about 120 ° C in an example table. Brown three-layer biocidal roofing granules (mixture of 10% biocidal granules + 90% non-biocidal granules)

Composition of the first ceramic layer g Mineral granules 1000 water 15 liquid sodium glass 24 kaolin 15 STANDART Lac L 900 Rich Pale Gold Bronze Powder (85% Cu, 15% Zn) 30 Composition of the second ceramic layer The granules are coated with a first layer 1000 water 15 liquid sodium glass 24 kaolin 15 STANDART Lac L 900 Rich Pale Gold Bronze Powder (85% Cu, 15% Zn) 30 Composition of the third ceramic layer The granules are coated with a second layer 1000 water 13

sodium perborate tetrahydrate 0.4 boric acid 0.4 lignosulfonate 0.2 liquid sodium glass 20 kaolin 13 yellow iron oxide dye 0.3 red iron oxide dye 1.5 titanium dioxide 0.6 technical coal 0.7 Post-treatment composition The granules are coated with a third layer 1000 water 5 Acronal A754 2 Silres5137 0.5

First layer: 1000 g of unpainted granules heated to about 120 ° C are coated with a premixed composition consisting of 15 g of water, 24 g of liquid sodium glass, 15 g of kaolin and 8 g of STANDART Lac L 900 Rich Gold Bronze Powder, containing 85% Cu and 15% Zn. The prepared pellets are annealed for 20 minutes at a temperature of about 500 ^° C, and then cooled to about 80 ° C.

After coating with the second layer, the granules are heated to about 120 ° C and coated with a premixed composition consisting of 15 g of water, 24 g of liquid sodium glass, 15 g of kaolin and 8 g of STANDART Lac L 900 Rich Gold Bronze Powder containing 85 g. % Cu and 15% Zn. The prepared granules are annealed for 20 minutes at about 500 ° C and then cooled to about 80 ° C.

Third layer: the preheated granules are coated with a composition containing 13 g of water, 0.4 g of sodium perborate tetrahydrate, 0.4 g of boric acid, 0.2 g of lignosulfonate, 20 g of liquid sodium glass, 13 g of kaolin, 0.3 g of yellow iron oxide dye, 1.5 g of red iron oxide dye, 0.6 g of titanium dioxide and 0.7 g of technical carbon. The resulting pellets are fired for 20 minutes at about 500 ° C and then cooled to about 80 ° C.

In the further processing step, the ceramicized granules are coated with a composition consisting of 5 g of water, 2 g of Acronal A754 and Silres 513. The obtained granules are dried at a temperature of about 120 ° C. Brown biocidal roofing granules coated with 2 ceramic layers

Composition of the first ceramic layer Mass, g Mineral granules 1000 water 15 liquid sodium glass (sodium silicate) 24 kaolin (clay) 15 STANDART Lac L 900 Rich Pale Gold Bronze Powder (85% Cu, 15% Zn) 8 Composition of the second ceramic layer The granules are coated with a first layer 1000 water 13 lignosulfonate 0.2 liquid sodium glass (sodium silicate) 20 kaolin (clay) 13

yellow iron oxide dye 0.3 red iron oxide dye 1.5 titanium dioxide 0.6 technical coal 0.7 Post-treatment composition The granules are coated with a second layer 1000 water 5 Acronal A754 2 Silres 5137 0.5

The granules are prepared according to the method described in Example 2.

example table. Black biocidal roofing granules coated with 2 ceramic layers

Composition of the first ceramic layer Mišių st Mineral granules 1000 water 15 lignosulfonate 0.2 liquid sodium glass (sodium silicate) 24 kaolin (clay) 15 red iron oxide dye 0.4 technical coal 1 STANDART Lac L 900 Rich Gold Bronze Powder (70% 4.5

Cu, 30% Zn) Composition of the second ceramic layer The granules are coated with a first layer 1000 water 13 lignosulfonate 0.2 liquid sodium glass (sodium silicate) 20 kaolin (clay) 13 red iron oxide dye 0.35 technical coal 0.9 Post-treatment composition Granules coated with a second layer 1000 water 5 Acronal A754 2 Silres 5137 0.5

The granules are prepared according to the method described in Example 2.

The resulting biocidal roofing granules with good weather resistance can be used in the roofing material as a protective layer throughout the service life.

To test the resistance of the obtained granules to biological contamination (biological growth), 8 samples of roofing granules were examined, of which 2 samples of biocidal granules (No. 1) and (No. 2), black and gray, can be obtained from a company that is a leader in the roofing pellet industry. These granules, the composition of which is kept secret, are generally used to protect the roof from biological growth, and have been taken as a reference example of the granules produced according to the present invention.

The granules of the present invention prepared according to Examples 1-4 were tested.

In addition, non-biocidal granules with the composition given in Table 7 were also tested to compare biocidal granules with non-biocidal granules in terms of their resistance to biological contamination.

example table. Black single layer conventional (non-biocidal) roofing granules

Ceramic layer composition g Mineral granules 1000 water 15 lignosulfonate 0.2 Liquid sodium glass 24 kaolin 15 red iron oxide dye 0.4 technical coal 1 Post-treatment composition Granules coated with a ceramic layer 1000 water 5 Acronal A754 2 Silres 5137 0.5

The biocidal stability of the samples was tested using Gloeocapsa sp. blue-green algae obtained from the IPPAS microalgae culture collection located in K. A. Timiriazevo v. of the Russian Academy of Sciences. Institute of Plant Physiology; registration number in the IPASS collection: IPPAS B-1203. Strains of Gloeocapsa sp. as was chosen as the object of study because it is one of the major species of microalgae damaging roof and road surfaces.

The resistance of the test beads to biological contamination caused by the cyanobacteria Gloeocapsa sp. Was evaluated on the basis of the optical density of the bacteria grown together with the beads by measuring light passing at 600 nm with a CLARIOStar plate reader. The measured optical density reflects the concentration of bacterial cells in the medium. In this case, the optical density of the culture is determined by the light scattering effect, which in turn is proportional to the concentration of bacterial cells in the medium. Thus, the higher the measured optical density of a bacterial culture, the greater the extent of biological growth (biological contamination).

The assays were performed in 24-well plates in 2 ml of prepared Gloeocapsa sp. culture in BG-11 medium diluted 1: 1 in “urban rain” medium. The experiment was started with an initial bacterial culture optical density of 0.01 OV / 600 nm.

Samples were taken once a week for a period of two weeks. Prior to sampling from each bead sample, the bacterial culture was mixed evenly by pipetting 5 times with a 1 ml Eppendorf-type pipette, then taking a 100 microliter sample and transferring to a 96-well plate for spectrophotometric measurements. Each sample was measured in triplicate. The studies were performed in a stationary BMB-II microbiological laminar simulating natural climatic conditions under laboratory conditions, including sterility, constant humidity, and temperature.

600 mg of each bead sample was tested in triplicate. Prior to the experiment, the beads were sterilized with 70% ethanol with vigorous stirring for 5 minutes, then washed three times with distilled water with vigorous stirring. The plates were placed on a rotary shaker, and the biological protection effectiveness of the beads was monitored for 2 weeks by continuously stirring the beads in a 24-well plate at 100 rpm.

Prior to measurement with a CLARIOStar plate reader, the plate was shaken for five minutes at 550 rpm, allowing an even distribution of the cyanobacterial culture in the well.

The findings of the study are presented in Table 8.

Table 8. Blue-green algae Gloeocapsa sp. optical density. (OT ₆₀₀ nm)

N r. Example 1 week (OT ₆₀₀ nm) Week 2 (OT ₆₀₀ nm) 1 Gray reference granules (mixing: 10/90) 0.62 1.06 2 Black reference granules (mixing: 10/90) 0.48 1.13 3 Example 1 (without mixing) 0.61 1.23 4 Example 2 (without mixing) 0.52 1.03 5 Example 3 (mixing: 20/80) 0.56 1.21 6 Example 4 (mixing: 10/90) 0.72 1.11 7 Example 7 (laboratory non-biocidal granules) 0.82 7.07 8 Black reference granules (ordinary non-biocidal granules) 0.91 7.47 9 Control Gloeocapsa sp, (without granules) * 1.10 8.46

* - culture medium with Gloeocapsa sp

Studies have shown that samples of biocidal roofing granules made in accordance with the present invention and currently on the market from No. 1 to 6 demonstrated relatively uniform results in resistance to bioinfection; Thus, it can be concluded that the coatings with biocidal granules according to the present invention have a resistance to biological growth for a period of time equivalent to the standard (reference granules) time.

When the biocidal granules are compared with the conventional granules, it can be observed that in the case of the latter, the optical density increases significantly, which also indicates the successful functioning of the biocidal granules produced according to the present invention.

At the same time, unlike granules known in the art, which use a unique copper raw material as a biocide, the granules of the invention use a copper-zinc alloy in the form of a brass dye.

Thus, the present invention makes it possible to produce biocidal roofing pellets, provides a higher technological level of use of the pellets due to commercially available components, and facilitates and reduces the production method. In addition, in some embodiments of the present invention, the cost of using biocidal beads is further reduced by eliminating the step of evenly distributing biocidal beads between conventional beads and eliminating intensive irrigation of the roof surface with intense watering to distribute active ions among conventional beads. successfully perform its function on the roof surface.

Claims (23)

DEFINITION OF THE INVENTION 1. Biocidal roofing granules comprising: crushed rock base; a ceramic coating comprising kaolin, liquid glass and a biocide, wherein the biocide comprises a brass powder which is a copper-zinc alloy with a particle size of 5 to 75 and the zinc content of the biocide is in the range of 15% to 30% by weight , where the coating layer of the biocide is in the range of 4.5 to 30 kg per tonne of base material. The biocidal roofing granules according to claim 1, wherein the amount of biocide is in the range of 4.5 kg to 8 kg per ton of base material. The biocidal roofing granules according to claim 1, wherein the amount of biocide is 30 kg per ton of base material. Biocidal roofing granules according to claim 3, mixed with non-biocidal granules in a ratio of 20 kg of biocidal roofing granules to 80 kg of non-biocidal roofing granules. The biocidal roofing granules of claim 1, wherein the ceramicized coating layer further comprises a dye or a mixture of a dye and a dispersant. The biocidal roofing beads of claim 1, wherein the biocidal beads further comprise an additional ceramic layer comprising kaolin, liquid glass, a dye or dye mixture, and a dispersant coating the surface of the beads. Biocidal roofing granules according to any one of claims 1 to 6, wherein the granules are further coated with a post-treatment composition comprising a latex or an industrial oil and water repellent. The biocidal roofing granules of claim 7, wherein the post-treatment composition further comprises an organic biocidal component. A process for the production of biocidal roofing granules according to claim 1, comprising the steps of: crushing and particle size distribution of rock-based material; preheating the crushed and particle-sized rock-based material; coating the preheated crushed and particle sized rock-based material with a composition comprising kaolin, liquid glass and a biocide to form granules; and firing the granules to form a ceramicized coating layer thereon. A method of manufacturing biocidal roofing granules according to claim 9, further comprising the steps of: coating the surface of the fired granules with a dye composition comprising kaolin, liquid glass, a dye or a mixture of dyes and a dispersant to paint the granules; and burning the painted granules. The method for producing biocidal roofing granules according to claim 9 or 10, further comprising the step of further treating: coating the surface of the granules with a post-treatment composition comprising a latex or an industrial oil and water repellent. The method for producing biocidal roofing granules according to claim 11, wherein the post-treatment composition further comprises an organic biocidal component. 13. Biocidal roofing granules comprising: a crushed rock base; a first inner layer of a ceramic coating comprising kaolin, a liquid glass and a biocide, and an outer layer of a ceramic coating comprising kaolin, a liquid glass and a biocide, wherein the biocide comprises brass powder containing copper alloy in both the inner and outer layers of copper; with a particle size in the range of 5 to 75 μm and a zinc content in the range of 15 to 30% by weight, where the total content of the biocidal product in both the inner and outer coatings is greater than 30 kg but not more than 60 kg per tonne of base material. The biocidal roofing granules according to claim 13, wherein the total amount of biocide in both the inner and outer layers of the coating is 60 kg per ton of base material. Biocidal roofing granules according to claim 14, mixed with non-biocidal granules in a ratio of 10 kg of biocidal roofing granules to 90 kg of non-biocidal roofing granules. The biocidal roofing granules of claim 13, wherein the outer ceramic coating layer further comprises a dye or mixture of dyes and a dispersant. The biocidal roofing granules of claim 13, wherein the biocidal granules further comprise an additional ceramicized outer layer comprising kaolin, liquid glass, a dye or a mixture of dyes, and a dispersant coating the surface of the granules. Biocidal roofing granules according to any one of claims 13 to 17, wherein the granules are further coated with a post-treatment composition comprising a latex or an industrial oil and water repellent. The biocidal roofing granules of claim 18, wherein the post-treatment composition further comprises an organic biocidal component. A method of manufacturing biocidal roofing granules according to claim 13, comprising the steps of: crushing and particle size distribution of rock-based material; preheating the crushed and particle-sized rock-based material; coating the preheated crushed and particle-sized rock-based material with a first composition comprising kaolin, liquid glass and a biocide to form granules; firing the granules to form a ceramicized coating layer thereon; cooling the burnt pellets to a temperature of about 80 ° C using equipment suitable for air flow and / or water; heating of coated granules; coating the fired granules with a second composition comprising kaolin, liquid glass and a biocide to form a second coating layer on the granules; and firing the granules to form a ceramicized second coating layer thereon. A process for the production of biocidal roofing granules according to claim 20, comprising the further steps of: using a painting composition comprising kaolin, liquid glass, a dye or a mixture of dyes and a dispersant to paint the granules with two coatings, and firing the painted granules. The method for producing biocidal roofing granules according to claim 20 or 21, further comprising the step of further coating the surface of the granules with a post-treatment composition comprising a latex or an industrial oil and water repellent. The method of making biocidal roofing granules according to claim 22, wherein the post-treatment composition further comprises an organic biocidal component.