MANUFACTURING PROCESS FOR FRICTION MATERIAL, INORGANIC LIQUID BINDER, USE OF LIQUID BINDER FOR MANUFACTURING FRICTION MATERIAL AND FRICTION MATERIAL

Abstract

This invention describes a process for manufacturing friction material and an inorganic liquid binder for use in the manufacture of friction materials. Specifically, the invention comprises a process for manufacturing friction material that uses a liquid binder that allows for process steps with a significant reduction in temperature, pressure, and manufacturing time, making the process more energy-efficient. Furthermore, it comprises a process step for manufacturing the liquid binder that allows the use of different types of inorganic precursors with crystalline and / or amorphous characteristics, through a mechanical activation process of the inorganic precursor.The present invention falls within the fields of chemical engineering, mechanical engineering, and materials engineering, focusing on friction materials for vehicle braking systems.

Description

1 / 25 Descriptive Report of Invention Patent Manufacturing Process of Friction Material, Inorganic Liquid Binder, Use of Liquid Binder for Manufacturing Friction Material and Friction Material Field of Invention

[0001] The present invention describes a process for manufacturing friction material and an inorganic liquid binder for use in the manufacture of friction materials. Specifically, the present invention comprises a process for manufacturing friction material that uses a liquid binder that allows for process steps with a significant reduction in temperature, pressure, and manufacturing time, making the process more energy-efficient. Furthermore, it comprises a process step for manufacturing the liquid binder that allows the use of different types of precursors, including inorganic precursors with crystalline and / or amorphous characteristics, through a mechanical activation process of the inorganic precursor. The present invention falls within the fields of chemical engineering, mechanical engineering, and materials engineering, focusing on friction materials for vehicle braking systems. Background of the Invention

[0002] Friction materials are widely used in the manufacture of brake system components, such as brake pads, brake linings and brake shoes, for small, medium and large vehicles for passenger or cargo transport, such as passenger cars, buses, trucks, trains, among others.

[0003] The manufacturing processes for friction materials for brake systems in the state of the art involve significant energy expenditure, mainly in the curing and molding stages, varying according to the raw materials used to form the friction material. Furthermore, the costs Petition 870200089617, dated 07 / 20 / 2020, page 6 / 41 2 / 25 energy costs are associated with the high temperatures and pressures required in these stages, as well as a large demand for process time at high temperatures and pressures.

[0004] Furthermore, the manufacture of the prior art friction material uses, in short, a mixture of a phenolic resin with a friction material and, subsequently, the mixture is subjected to pressing under high temperature for curing of the resin and compaction of the mixture.

[0005] However, phenolic resin is a material that can pose risks to the environment, since, due to polluting sources from industry, domestic and agricultural activities, phenolic resin can be deposited in the soil or rivers, potentially causing harm to wildlife. Furthermore, it has a relatively high carbon footprint, generating between 1.3 and 2.3 kg of carbon dioxide per kg of resin produced.

[0006] In the search for the state of the art in scientific and patent literature, the following documents were found that deal with the subject:

[0007] Document WO2014081277 discloses a solid volcanic ash geopolymer composition for the production of a geopolymer composite for use in construction materials and / or friction materials, where the use of volcanic ash is comparable to the use of fly ash. To obtain volcanic ash at the desired particle size, the document describes a drying, grinding, and sieving process of the volcanic ash, a process carried out before the mixing process to obtain the geopolymer, which already requires energy expenditure in a step prior to the geopolymer mixing, making the process energy inefficient. Furthermore, document WO2014081277 does not mention the formation of a liquid inorganic binder through the combination of previously ground inorganic precursors and a solution, obtaining a solution and / or suspension with varying viscosities for mixing with the other raw materials of the friction material. Petition 870200089617, dated 07 / 20 / 2020, page 7 / 41 3 / 25

[0008] Document US2017016500 discloses a friction material for manufacturing brake pads, in which the manufacturing process involves a premixing step of an inorganic binder made from kaolin or metakaolin and sodium hydroxide in a mixer. Subsequently, this gel-like mixture is placed in a mold for pressing under predefined temperatures and pressures within a time range. The mixture is then placed in an oven for drying, and finally, the dried paste is returned to the mixer to be reduced to powder form. In this way, a solid inorganic binder is formed, which is added to the other raw materials to form the friction material and again subjected to the pressing process.However, document US2017016500 does not mention the formation of a liquid inorganic binder through the combination of previously ground inorganic precursors and a solution, obtaining a solution and / or suspension with varying viscosities for mixing with the other raw materials of the friction material.

[0009] Document WO2020039396 discloses a method for preparing a friction material for brake pads, which includes a step of mixing sodium hydroxide and sodium silicate with commercial metakaolin to obtain a wet paste. This wet paste undergoes a drying process until a dry geopolymer aggregate is obtained. Subsequently, the dry aggregate is ground into a powder, and the powder is used as an inorganic binder for mixing with the other raw materials of the friction material. However, document WO2020039396 does not mention the formation of a liquid inorganic binder by mixing mechanically activated inorganic precursors through grinding and a solution, obtaining a solution and / or suspension with varying viscosities for mixing with the other raw materials of the friction material.Furthermore, it mentions that the solid inorganic binder must possess an amorphous characteristic when evaluated by X-ray diffraction techniques, without mentioning that it could have a crystalline characteristic. Petition 870200089617, dated 07 / 20 / 2020, page 8 / 41 4 / 25

[0010] Thus, as can be inferred from the literature reviewed, no documents were found anticipating or suggesting the teachings of the present invention, so the solution proposed here has novelty and inventive activity compared to the state of the art.

[0011] Thus, the state of the art lacks manufacturing processes for friction materials that provide reduced energy costs with reduced pressures and temperatures, and that optimize manufacturing time, as well as make the process easier. Furthermore, the state of the art lacks a manufacturing process that allows the use of a variety of inorganic precursors for the formation of the inorganic binder. Summary of the Invention

[0012] Thus, the present invention solves the problems of the prior art by means of a manufacturing process for friction material that uses a liquid inorganic binder produced via an initial step of mechanical activation of crystalline and / or amorphous inorganic precursors by means of grinding, and thermal synthesis with the mixture of oxides and / or hydroxides and / or silicates of alkali and alkaline earth metals with inorganic precursors. Furthermore, the manufacturing process that uses liquid inorganic binder reduces energy costs, as it does not require a drying and grinding step of the inorganic binder for mixing, being used in the liquid state for mixing with other components of the friction material, as well as performing the cold forming step, with reduced temperature, pressure and compression time compared to the prior art.

[0013] In a first object, the present invention discloses a process for manufacturing friction material comprising at least the following steps: a. a combination of at least one liquid binder with at least one complementary material, forming a mixture; Petition 870200089617, dated 07 / 20 / 2020, page 9 / 41 5 / 25 b. cold forming of the mixture with predetermined temperature, pressure and compression time; and c. completion of the mixture curing process at predetermined temperature and time.

[0014] Furthermore, an object of the invention is a process for manufacturing liquid binder comprising at least the following steps: a. mechanical activation of at least one inorganic precursor by means of milling, forming a crystalline and / or amorphous structure; and b. combination of the mechanically activated inorganic precursor with at least one solution of alkali / alkaline earth metal hydroxide and / or alkali / alkaline earth metal silicate, forming the liquid binder.

[0015] In a second object, the present invention provides an inorganic liquid binder comprising a combination of at least one solution and at least one mechanically activated crystalline and / or amorphous inorganic precursor, wherein said solution comprises at least one alkali / alkaline earth metal hydroxide and / or at least one alkali / alkaline earth metal silicate.

[0016] In a third object, the present invention discloses the use of an inorganic liquid binder for the manufacture of friction material comprising a mixture of inorganic liquid binder with at least one complementary material, wherein: a. the liquid binder comprises a combination of at least one solution and at least one mechanically activated crystalline and / or amorphous inorganic precursor, wherein said solution comprises at least one alkali / alkaline earth metal hydroxide and / or at least one alkali / alkaline earth metal silicate; and b. the supplementary material comprises at least one of the following: i. mineral filler; Petition 870200089617, dated 07 / 20 / 2020, page 10 / 41 6 / 25 ii. organic fiber; iii. metallic fiber; iv. inorganic fiber; v. friction; vi. lubricant; vii. tenacifying; or viii. a combination of the above.

[0017] In a fourth object, the present invention provides a friction material comprising a mixture of at least one inorganic liquid binder and at least one complementary material, wherein the binder comprises a combination of at least one solution and at least one mechanically activated crystalline and / or amorphous inorganic precursor, wherein said solution comprises at least one alkali / alkaline earth metal hydroxide and / or at least one alkali / alkaline earth metal silicate.

[0018] These and other objects of the invention will be immediately appreciated by those skilled in the art and will be described in detail below. Brief Description of the Figures

[0019] The following figures are presented:

[0020] Figure 1 shows the results of a comparative braking efficiency test conducted on a dynamometer before the fade stage between a prior art material and the present invention.

[0021] Figure 2 shows the results of braking efficiency tests conducted on a dynamometer after the fade step between the prior art material and the present invention.

[0022] Figure 3 shows an embodiment of the present invention in the form of brake pads, after the braking efficiency testing procedure on a dynamometer.

[0023] Figure 4 shows an embodiment of the present invention in the form of brake discs after the braking efficiency test procedure. Petition 870200089617, dated 07 / 20 / 2020, page 11 / 41 7 / 25 on a dynamometer. Detailed Description of the Invention

[0024] The descriptions that follow are given by way of example and are not limiting to the scope of the invention and will make clearer the subject matter of this patent application.

[0025] The present invention describes a process for manufacturing friction material that allows the use of different types of inorganic precursors, overcoming a limitation of the prior art, through an initial mechanical activation step by grinding the inorganic precursor, a step that precedes the step of mixing the inorganic precursor with a solution.

[0026] In a first object, the present invention discloses a process for manufacturing friction material comprising at least the following steps: a. a combination of at least one liquid binder with at least one complementary material, forming a mixture; b. cold forming of the mixture with predetermined temperature, pressure and compression time; and c. completion of the mixture curing process at predetermined temperature and time.

[0027] In one embodiment, the liquid binder is manufactured by means of at least the following steps: mechanical activation of at least one inorganic precursor by means of milling, forming a crystalline and / or amorphous structure; and combination of the mechanically activated inorganic precursor with at least one solution of alkali / alkaline earth metal hydroxide and / or alkali / alkaline earth metal silicate, forming the liquid binder.

[0028] In one embodiment, the mechanical activation step of the inorganic precursor by means of grinding allows the use of a variety of inorganic precursor materials, since, by means of grinding, the Petition 870200089617, dated 07 / 20 / 2020, page 12 / 41 8 / 25 The inorganic precursor is ground to a size range that provides a fine and suitable particle size.

[0029] In one embodiment, the mechanical activation step of at least one inorganic precursor grinds the precursor to a particle size range of less than 500 µm. In another embodiment, the mechanical activation step grinds the precursor to a particle size range of less than 100 µm. In one embodiment, the particle size range of the inorganic precursor ground in the mechanical activation step comprises a suitable fine particle size range.

[0030] In one embodiment, the grinding of the inorganic precursor is done with the aid of mills. Through the parameterization of said mills, an optimal process for grinding the inorganic precursor is achieved, reaching the appropriate fine particle size. In one embodiment, the grinding of the inorganic precursor is done dry. In one embodiment, the grinding of the inorganic precursor is done wet. In one embodiment, the grinding of the inorganic precursor is done with a ball mill. In one embodiment, the grinding of the inorganic precursor is done with or without the combination of a prior grinding. In one embodiment, the grinding of the inorganic precursor is done with different impact mills with or without the combination of prior grinding in different mills. The use of one type or another will depend on the desired final particle size, productivity, and grinding cost per quantity of inorganic precursor.

[0031] In one embodiment, the step of combining the mechanically activated inorganic precursor with at least one solution of alkali / alkaline earth metal hydroxide and / or alkali / alkaline earth metal silicate forms an inorganic liquid binder that improves the solubility of the mixture and facilitates mixing between the liquid binder and the complementary materials of the friction material.

[0032] In one embodiment, alkali / alkaline earth metal silicate comprises at least one of: Liquid Sodium Silicate; Potassium Silicate Petition 870200089617, dated 07 / 20 / 2020, page 13 / 41 9 / 25 liquid; anhydrous sodium silicate; anhydrous potassium silicate; liquid lithium silicate; anhydrous lithium silicate; or a combination thereof. For illustrative purposes, alkali / alkaline earth metal silicate basically comprises silicon oxide associated with an alkali / alkaline earth metal oxide. In one embodiment, the alkali / alkaline earth metal silicate comprises at least silicon oxide associated with the oxide of an alkali metal. In one embodiment, the metal silicate comprises at least silicon oxide associated with the oxide of an alkaline earth metal.

[0033] In one embodiment, the alkali / alkaline earth metal hydroxide comprises at least one of: Potassium hydroxide; Sodium hydroxide; Aluminum hydroxide; Magnesium hydroxide; Calcium hydroxide; or a combination thereof. In one embodiment, the metal hydroxide comprises alkali metal hydroxide. In one embodiment, the metal hydroxide comprises alkaline earth metal hydroxide. In one embodiment, the metal hydroxide is selected based on the metal silicate used.

[0034] In one embodiment, the liquid binder is a solution and / or suspension and comprises viscosity in a range between 10 and 100000 cP. In another embodiment, the liquid binder comprises viscosity between 100 and 50000 cP.

[0035] In a first embodiment of the binder formulation it comprises a range of 22.6 to 56% liquid silicate, a range of 35 to 46% of an inorganic precursor and a range of 0 to 10% water as a processing agent.

[0036] In a second formulation, the binder comprises a range of 22.6 to 56% liquid silicate, a range of 44 to 55% of an inorganic precursor, and a range of 0 to 10% water.

[0037] In a third embodiment of the binder formulation, it comprises a range of 22.6 to 50% liquid silicate, a range of 50 to 70.40% of a first inorganic precursor and a range of 0 to 10% of a Petition 870200089617, dated 07 / 20 / 2020, page 14 / 41 10 / 25 second inorganic precursor, a range of 0 to 22% of a processing agent, a range of 0 to 22% of a boosting agent, and a range of 0 to 10% of water.

[0038] In a fourth embodiment of the binder formulation, it comprises a range of 22.6 to 50% liquid silicate, a range of 10 to 40% of a first inorganic precursor and a range of 10 to 40% of a second inorganic precursor, a range of 0 to 22% of a processing agent, a range of 0 to 19% of a boosting agent, and a range of 0 to 10% of water.

[0039] In a fifth embodiment of the binder formulation, it comprises a range of 22.6 to 50% liquid silicate, a range of 50 to 75% of an inorganic precursor, a range of 0 to 22% of a processing agent, a range of 0 to 19% of a reinforcing agent, and a range of 0 to 10% water.

[0040] In a sixth embodiment of the binder formulation, it comprises a range of 22.6 to 50% liquid silicate, a range of 50 to 75% of an inorganic precursor, a range of 0 to 22% of a processing agent and a range of 0 to 22% of a reinforcing agent.

[0041] In one embodiment, the liquid silicate comprises at least one of: mineral fiber; lithium silicate; corrected potassium silicate R = 1.5; activated potassium silicate; corrected sodium silicate R = 1.5; potassium silicate; sodium silicate; or a combination thereof.

[0042] In one embodiment, the inorganic precursor comprises at least one of the materials belonging to the families of igneous, metamorphic or sedimentary rocks and / or by-products and co-products of the steel, thermoelectric, ceramic, mining and construction industries such as, for example, metakaolin, clays, basaltic rocks, granites, sandstones, carbonates, phosphates, silicates, aluminates, blast furnace slag, heavy and fly ash from coal and / or biomass, rice husk ash, glass, tailings, sludge, concentrates, demolition waste, or a Petition 870200089617, dated 07 / 20 / 2020, page 15 / 41 11 / 25 combination of the previous ones.

[0043] In one embodiment, the processing agent comprises at least one compound possessing the following functionalities: surface modifiers, surfactants, compatibilizing agents (organosilanes, cellulose-based compounds and their derivatives, such as nanocellulose, for example), thickeners, dispersants and / or flocculants, polymeric and / or inorganic rheological modifiers, binders, plasticizers or chelating agents (such as, for example, fatty and / or carboxylic acids, polyphenols, sugars, starches, amines, vinyls, ammonia, acrylates, stearates, phosphates, sulfates, sulfonates, alcohols, glycols and polymers soluble in polar liquids, of natural and / or synthetic source and / or derivatives) and / or a combination thereof.

[0044] In one embodiment, the reinforcing agent for the inorganic binder comprises at least one of the following: micrometric and / or nanometric fibers of organic, inorganic or metallic nature (such as, for example, basalt fiber, glass fiber, carbon fiber, halloysite, wollastonite, nanocellulose fiber) and / or a combination thereof.

[0045] In one embodiment, the complementary material comprises complementary raw materials commonly used in the manufacture of friction materials. In one embodiment, the complementary material comprises at least one of: mineral filler; organic fiber; metallic fiber; inorganic fiber; friction agent; lubricant; toughener; or a combination thereof.

[0046] In one embodiment, the mineral filler comprises at least one or a combination thereof: barite; calcium carbonate; kaolin; hydrated lime; fluorite; talc; bentonite; among others.

[0047] In one embodiment, organic fiber comprises at least one or a combination thereof: aramid; cellulose; acrylic; carbon; among others.

[0048] In one embodiment, the metallic fiber comprises at least Petition 870200089617, dated 07 / 20 / 2020, page 16 / 41 12 / 25 one or a combination of: copper; steel; aluminum; zinc; brass; among others.

[0049] In one embodiment, the inorganic fiber comprises at least one or a combination of: fiberglass; basalt; silica; aluminosilicate; titanates; among others.

[0050] In one embodiment, the attritive agent comprises at least one or a combination thereof: alumina; zirconite; chromium oxide; silicon oxide; chromite; zirconium oxide; iron oxide; among others.

[0051] In one embodiment, the lubricant comprises at least one or a combination thereof: natural graphite powder with different purities; natural graphite flakes with different purities; synthetic graphite; metallic sulfides such as tin, iron, molybdenum, copper, manganese, among others.

[0052] In one embodiment, the toughener comprises at least one or a combination thereof: recycled rubber powder; SBR / NBR rubber powder; rubber pellets; among others.

[0053] In one embodiment, the step of forming a mixture between at least one liquid binder and at least one complementary material in the friction material manufacturing process is carried out by means of simultaneous or incremental mixing and granulation, resulting in a mixture with adequate fluidity for the subsequent steps of cold forming and final curing of the mixture.

[0054] In one embodiment, the friction material is manufactured in a mechanical stirrer. In one embodiment, the manufacturing is done in a conventional mixer specifically for liquids. In one embodiment, the manufacturing is done in a mixer for solids, liquids and / or paste / gel mixtures. In one embodiment, the manufacturing is done with a predetermined rotation selected according to the viscosity of the mixture. In one embodiment, the inorganic precursor is added gradually until complete homogenization.

[0055] In one embodiment, the cold forming step of the mixture between liquid binder and complementary material is carried out without there being Petition 870200089617, dated 07 / 20 / 2020, page 17 / 41 13 / 25 high demand for high temperatures / heat, pressure and time, i.e., the cold forming stage reduces energy costs.

[0056] In one embodiment, the cold forming step of the mixture is carried out in a temperature range below 150 °C. In another embodiment, the cold forming step of the mixture is carried out in a temperature range from ambient temperature up to 100 °C. In yet another embodiment, the cold forming step of the mixture is carried out in a temperature range from 0 °C to 150 °C.

[0057] In one embodiment, the cold forming step of the mixture is carried out in a pressure range less than or equal to 300 MPa. In another embodiment, the cold forming step of the mixture is carried out in a pressure range between 0 and 200 MPa.

[0058] In one embodiment, the cold forming step of the mixture is carried out in a time range between 2 and 300 seconds. In another embodiment, the cold forming step of the mixture is carried out in a time range of 6 to 120 seconds.

[0059] In one embodiment, the final curing step of the mixture between liquid binder and complementary material is carried out in a temperature range of 10 to 500 °C. In another embodiment, the final curing step of the mixture is carried out in a temperature range of 25 to 400 °C.

[0060] In one embodiment, the final curing step of the mixture between liquid binder and complementary material is carried out in a time range of 5 minutes to 48 hours. In another embodiment, the final curing step of the mixture is carried out in a time range of 15 minutes to 24 hours.

[0061] In one embodiment, the manufacturing process of friction material comprises an additional final stage of finishing and processing of the friction material, in which cutting, painting, stamping and packaging of the material are carried out.

[0062] The manufacturing process of friction material of the present Petition 870200089617, dated 07 / 20 / 2020, page 18 / 41 14 / 25 The invention provides several energy and environmental advantages, such as the mechanical activation step through grinding in the liquid binder manufacturing process, which allows the use of a variety of inorganic precursors, forming partial or total crystalline and / or amorphous structures.

[0063] Furthermore, it offers the advantage that the combination of the mechanically activated inorganic precursor with at least one solution of alkali / alkaline earth metal hydroxide and / or alkali / alkaline earth metal silicate, forming the liquid binder, improves solubility and facilitates mixing, which allows the energy demand for the subsequent steps of friction material formation to be considerably reduced, since it allows the forming to be done cold (at significantly lower temperatures compared to the prior art), under considerably lower pressure than in the prior art, or even without pressure, and with an extraordinarily shorter compression time than in the prior art. Moreover, it has the advantage of allowing curing to be carried out at relatively low temperatures and with a reduced process time compared to the prior art.

[0064] Furthermore, the mechanical activation step of an inorganic precursor through grinding, forming a partial or total crystalline and / or amorphous structure, is a highly complex process step that aims to achieve a fine and suitable particle size that provides the aforementioned advantages.

[0065] In a second object, the present invention provides an inorganic liquid binder comprising a combination of at least one solution and at least one mechanically activated crystalline and / or amorphous inorganic precursor, wherein said solution comprises at least one alkali / alkaline earth metal hydroxide and / or at least one alkali / alkaline earth metal silicate.

[0066] In one embodiment, the inorganic precursor is mechanically activated by means of a grinding process, which allows the use of Petition 870200089617, dated 07 / 20 / 2020, page 19 / 41 15 / 25 a variety of inorganic materials / precursors, which gives the manufacturer greater possibilities for combinations or choice of inorganic precursors. Furthermore, through mechanical activation, it allows the inorganic precursor to have partially or totally crystalline and / or amorphous characteristics.

[0067] In one embodiment, the inorganic liquid binder improves solubility and facilitates mixing with other complementary friction material, which allows the energy demand for subsequent friction material formation steps to be considerably reduced. Furthermore, it allows the friction material forming step to be carried out cold, with significantly lower temperature, pressure, and compression time compared to the prior art. In addition, it allows curing to be performed with reduced temperature and process time compared to the prior art.

[0068] In a third object, the present invention discloses the use of an inorganic liquid binder for the manufacture of friction material comprising a mixture of inorganic liquid binder with at least one complementary material, wherein: a. the liquid binder comprises a combination of at least one solution and at least one mechanically activated crystalline and / or amorphous inorganic precursor, wherein said solution comprises at least one alkali / alkaline earth metal hydroxide and / or at least one alkali / alkaline earth metal silicate; and b. the supplementary material comprises at least one of the following: i. mineral filler; ii. organic fiber; iii. metallic fiber; iv. inorganic fiber; v. friction; vi. lubricant; Petition 870200089617, dated 07 / 20 / 2020, page 20 / 41 16 / 25 vii. tenacifying agent; or viii. a combination of the above.

[0069] In one embodiment, the use of an inorganic liquid binder for the manufacture of friction material brings several energy and environmental advantages to the manufacturing process and provides a friction material with enhanced and improved characteristics. In one embodiment, the mixture between at least one inorganic liquid binder and at least one complementary friction material results in a mixture with adequate fluidity for the subsequent forming and curing steps, which provides a reduction in temperature, pressure and process time, being more energy efficient.

[0070] In a fourth object, the present invention provides a friction material comprising a mixture of at least one inorganic liquid binder and at least one complementary material, wherein the binder comprises a combination of at least one solution and at least one mechanically activated crystalline and / or amorphous inorganic precursor, wherein said solution comprises at least one alkali / alkaline earth metal hydroxide and / or at least one alkali / alkaline earth metal silicate. Example 1 - Inorganic liquid binder manufacturing process

[0071] The examples shown here are intended only to illustrate one of the numerous ways of carrying out the invention, however without limiting its scope.

[0072] In this example, an inorganic liquid binder was developed for use in the manufacture of friction materials. Several formulations were tested and developed with the aim of obtaining an inorganic liquid binder with adequate fluidity for mixing with other common components of friction materials.

[0073] The process of obtaining inorganic liquid binder basically follows two steps: the first being the mechanical activation of the Petition 870200089617, dated 07 / 20 / 2020, page 21 / 41 17 / 25 minus an inorganic precursor by means of milling, forming crystalline and / or amorphous structures; and the second being thermal synthesis with the combination of the milled inorganic precursor with at least one solution of alkali / alkaline earth metal hydroxide and / or alkali / alkaline earth metal silicate, forming the liquid binder.

[0074] Obtaining an inorganic liquid binder from the mixture of at least one mechanically activated inorganic precursor and at least one solution of alkali / alkaline earth metal hydroxide and / or alkali / alkaline earth metal silicate, without the need for drying and grinding after the mixing step, is an important advantage of the process of the present invention, since it eliminates the need for drying at high temperatures and subsequent grinding of the mixture of the inorganic precursor with the solution, steps that are performed in the prior art. This characteristic of the process considerably improves the energy efficiency of the process, reducing the energy required in the form of heat from the drying furnaces.

[0075] In the liquid binder manufacturing process of the present invention, the initial step of mechanically activating at least one inorganic precursor by means of grinding is the most important step in the process, differentiating the binder production from the prior art, since it allows the use of a variety of inorganic precursors.

[0076] The mechanical activation step of the inorganic precursor grinds the inorganic precursor to a suitable fine particle size range. This step requires high complexity in execution to achieve the appropriate fine particle size, since the process of the present invention allows the use of various types of inorganic precursors in the manufacture of the inorganic liquid binder of the present invention. In this example, suitable fine particle sizes between 25 μm and 45 μm were obtained, these particle sizes being much smaller than those of the prior art.

[0077] The activated inorganic precursor combination step Petition 870200089617, dated 07 / 20 / 2020, page 22 / 41 18 / 25 mechanically with the alkali / alkaline earth metal hydroxide and / or alkali / alkaline earth metal silicate solution is made in a mixer for a predetermined time, forming a solution and / or suspension with varying viscosities.

[0078] In this example, crystalline and / or amorphous inorganic precursors with a high percentage of SiO2 and Al2O3 were used, such as igneous rocks; kaolins; metakaolins; rice husk ash; blast furnace slag; fly ash; wollastonite; and / or glasses.

[0079] Furthermore, mixtures of oxides and / or hydroxides and / or silicates of alkali and alkaline earth metals in solution and / or suspension were used.

[0080] In a first example of a liquid binder formulation, it comprises a range of 22.6 to 56% of corrected potassium silicate R = 1.5 or corrected sodium silicate R = 1.5; a range of 35 to 46% of metakaolin; and a range of 0 to 10% of water.

[0081] In a second example of liquid binder formulation, it comprises a range of 22.6 to 56% of corrected potassium silicate R = 1.5, or potassium silicate, or sodium silicate, or corrected sodium silicate R = 1.5; a range of 44 to 55% of rice husk ash; and a range of 0 to 10% of water.

[0082] In a third example of a liquid binder formulation, it comprises a range of 22.6 to 50% of R = 1.5 corrected potassium silicate, or potassium silicate, or sodium silicate, or R = 1.5 corrected sodium silicate; a range of 50 to 70.4% of blast furnace slag; a range of 0 to 10% of rice husk ash; a range of 0 to 2% of aminosilane; a range of 0 to 2% of carboxymethylcellulose; a range of 0 to 10% of polyvinyl alcohol; a range of 0 to 5% of glycerol; a range of 0 to 1% of polyethylene glycol; a range of 0 to 1% of hexamethylcellulose; a range of 0 to 1% of polyacrylamide; a range of 0 to 10% of basalt fiber; a range of 0 to 3% of glass fiber; a range of 0 to 3% carbon fiber; a range of 0 to 3% halloysite; a range of 0 to 3% wollastonite; and a range of 0 to 10% water. Petition 870200089617, dated 07 / 20 / 2020, page 23 / 41 19 / 25

[0083] In a fourth example of a liquid binder formulation comprising a range of 22.6 to 50% of R = 1.5 corrected potassium silicate, or potassium silicate, or sodium silicate, or R = 1.5 corrected sodium silicate; a range of 10 to 40% of rice husk ash; a range of 10 to 40% of wollastonite; a range of 0 to 2% of aminosilane; a range of 0 to 2% of carboxymethylcellulose; a range of 0 to 10% of polyvinyl alcohol; a range of 0 to 5% of glycerol; a range of 0 to 1% of polyethylene glycol; a range of 0 to 1% of hexamethylcellulose; a range of 0 to 1% of polyacrylamide; a range of 0 to 10% of basalt fiber; a range of 0 to 3% of glass fiber; a range of 0 to 3% carbon fiber; a range of 0 to 3% halloysite; and a range of 0 to 10% water.

[0084] In a fifth example of liquid binder formulation comprising a range of 22.6 to 50% potassium silicate, a range of 50 to 75% fly ash, a range of 0 to 2% aminosilane, a range of 0 to 2% carboxymethylcellulose, a range of 0 to 10% polyvinyl alcohol, a range of 0 to 5% glycerol, a range of 0 to 1% polyethylene glycol, a range of 0 to 1% hexamethylcellulose, a range of 0 to 1% polyacrylamide, a range of 0 to 10% basalt fiber, a range of 0 to 3% glass fiber, a range of 0 to 3% carbon fiber, a range of 0 to 3% halloysite and a range of 0 to 10% water.

[0085] In a sixth example of a liquid binder formulation, it comprises a range of 22.6 to 50% sodium silicate, or sodium silicate corrected R = 1.5 or potassium silicate corrected R = 1.5; a range of 50 to 75% fly ash; a range of 0 to 2% aminosilane; a range of 0 to 2% carboxymethylcellulose; a range of 0 to 10% polyvinyl alcohol; a range of 0 to 5% glycerol; a range of 0 to 1% polyethylene glycol; a range of 0 to 1% hexamethylcellulose; a range of 0 to 1% polyacrylamide; a range of 0 to 10% basalt fiber; a range of 0 to 3% glass fiber; a range of 0 to 3% carbon fiber; a range of 0 to 3% halloysite; and a range of 0 to 3% wollastonite. Petition 870200089617, dated 07 / 20 / 2020, page 24 / 41 20 / 25

[0086] In this way, the developed liquid binder formulations provide an inorganic liquid binder for application in the formulation of friction materials that brings advantages to the manufacturing process, such as improved solubility and greater ease of mixing with other complementary friction materials, which allows the energy demand for the subsequent stages of friction material formation to be considerably reduced. Example 2 - Manufacturing process of friction material

[0087] In this example, a friction material was developed from the combination of at least one inorganic liquid binder, as exemplified in example 1, with at least one complementary material commonly used in the manufacture of friction materials.

[0088] Furthermore, a friction material for brake friction elements was developed that allows the replacement of phenolic resin with an inorganic liquid binder, since phenolic resin, used in approximately 95% of friction materials in the state of the art, can pose risks to the environment, as, due to polluting sources from industrial, domestic and agricultural activities, phenolic resin can be deposited in the soil or rivers, potentially causing harm to wildlife. In addition, it has a relatively high carbon footprint, generating between 1.3 and 2.3 kg of carbon dioxide per kg of resin produced.

[0089] The first stage in the manufacture of friction material is the stage of obtaining the inorganic precursor, in which at least one inorganic precursor is mechanically activated by grinding until a suitable fine particle size range is obtained.

[0090] The second stage of the process is thermal synthesis by mixing the ground inorganic precursor with at least one solution of alkali and alkaline earth metal hydroxide and / or silicate, forming an inorganic liquid binder, in which the binder is a solution and / or suspension with varying Petition 870200089617, dated 07 / 20 / 2020, page 25 / 41 21 / 25 viscosities. This mixture is made in commercial mixers used in the manufacturing processes of friction materials.

[0091] The third stage of the process is the mixing of the inorganic liquid binder with raw materials commonly used in the manufacture of friction materials, such as mineral fillers, organic fibers, metallic fibers, inorganic fibers, friction agents, lubricants, tougheners, or a combination thereof. This mixing is carried out in commercial mixers used in the manufacture of friction materials.

[0092] The combination of the inorganic liquid binder with other friction material raw materials is associated with a formulation mixing and / or premixing process of the raw materials by means of mixing and granulation, in simultaneous or incremental ways, which results in a mixture with viscosity suitable for subsequent processing steps, such as forming and post-curing steps.

[0093] Furthermore, the next step is the cold forming of the liquid binder mixture with friction material raw materials, and was carried out at temperatures ranging from ambient temperature to 100 °C, with compaction pressures from 0 to 200 MPa and process times between 6 and 120 seconds.

[0094] The next step, in this example, is the post-curing step of the mixture formed in the previous step, and was carried out at a temperature between 25 and 400 °C and with a processing time between 15 minutes and 24 hours.

[0095] Furthermore, the final stage of manufacturing friction material comprises a finishing and processing stage of the material, which includes painting, cutting, stamping and packaging.

[0096] In this example, a material produced with the aforementioned steps was tested and applied to a 0 256 x 22 mm front brake, with an applied inertia of 65 kg.m2 evaluated via the Ak-Master-1998 procedure, widely used to evaluate friction materials. The test results are illustrated in figures 1 and 2. Petition 870200089617, dated 07 / 20 / 2020, page 26 / 41 22 / 25

[0097] The graphs in figures 1 and 2 show a comparison of the coefficient of friction under different brake application conditions, such as pressure, temperature and speed, between a commercial material used in replacement for light vehicles and the proposed material produced with the technology described in this invention.

[0098] In this example, it is possible to note that the material proposed by the present invention has an initial coefficient of friction very similar to the prior art material used in the comparison, and that it does not experience temperature loss during the step that evaluates the coefficient of friction with increasing temperature (Fade step). Another point to note is the higher friction compared to the material used as a comparison, demonstrating the high potential of the technology for use in friction materials.

[0099] Figures 3 and 4 show photographs taken after the dynamometer test, indicating the integrity of the material under the conditions imposed in the test, attesting that it has satisfactory mechanical resistance for the application. Another point to note is the low aggression to the disc, despite the inorganic nature of the binder.

[0100] Table 1 below shows a comparative analysis of the wear results, again demonstrating the similarity between the prior art materials and the potential use of the technology of the present invention. Table 1 - Comparison of Wear Results Material Test No. Disc Wear (g) (mm) Average (mm) Average (g) Baseline AM DL-0455 / 13 1.1 0.010 1.319 16.93 Present Invention DL-0180 / 19 4.1 0.024 1.240 16.05

[0101] Table 2 below summarizes a standard brake noise assessment result, the results of which were evaluated using the SAE procedure. Petition 870200089617, dated 07 / 20 / 2020, page 27 / 41 23 / 25 J2521 2013, with a description of the percentage of noisy braking incidents, frequencies of noise occurrence, as well as sound intensity. Table 2 - Occurrence of Noise in the Friction Material of the Present Invention (SAE Procedure J2521-2013) Main Peaks Only Number of noisy brakings Percentage of noisy braking Frequency range Global limit Drag Deceleration rear / front Global Drag Deceleration back / front 2 kHz at >70db(A) 84 47 29 8 4.4% 4.4% 4.4% 4.0% 16 kHz >80db(A) 61 34 21 6 3.2% 3.2% 3.2% 3.0% 2 kHz at >70db(A) 40 31 8 1 2.1% 2.9% 1.2% 0.5% 4 kHz >80db(A) 34 26 7 1 1.8% 2.4% 1.1% 0.5% 4 kHz to >70db(A) 2 0 2 0 0.1% 0.0% 0.3% 0.0% 6 kHz >80db(A) 0 0 0 0 0.0% 0.0% 0.0% 0.0% 6 kHz at >70db(A) 9 0 7 2 0.5% 0.0% 1.1% 1.0% 10 kHz >80db(A) 5 0 5 0 0.3% 0.0% 0.8% 0.0% 10 kHz at >70db(A) 33 16 12 5 1.7% 1.5% 1.8% 2.5% 14 kHz >80db(A) 22 8 9 5 1.1% 0.8% 1.4% 2.5% 14 kHz to >70db(A) 0 0 0 0 0.0% 0.0% 0.0% 0.0% 16 kHz >80db(A) 0 0 0 0 0.0% 0.0% 0.0% 0.0% N Total number of braking actions 1917 1064 653 200

[0102] Table 3 below shows a comparison between the average noise found for the commercial material of the prior art and the present invention. It is possible to verify again the similarity and potential of the invention in the development of friction materials. Petition 870200089617, dated 07 / 20 / 2020, page 28 / 41 24 / 25 Table 3 - Noise comparison Material Noise level (% stops > 70 dB) Baseline AM (Average) 3 Present Invention 4,4

[0103] As can be seen, the manufacturing process of friction material of the present invention promotes greater energy efficiency, since it uses expressively low temperatures in the forming and post-curing processes, uses substantially low pressure in the mixture forming stage and has an extraordinarily shorter process time in the forming and post-curing processes.

[0104] The aforementioned energy advantages cited above are provided by the use of the inorganic liquid binder developed in the present invention, wherein said binder is formed by at least one mechanically activated inorganic precursor mixed with at least one solution of alkali / alkaline earth metal hydroxide and / or alkali / alkaline earth metal silicate.

[0105] Furthermore, the difference between this invention and the state of the art is the formation of an inorganic precursor in the solid phase from the mechanical activation step of the precursors by means of grinding, which differs from the thermal activation reported in Davidovits' theory (Davidovits, J., 2015). Geopolymer. Chemistry and application. Saint-Quentin: Institut Géopolymere) and the alkaline activation described by Provis (Provis, JL, van Deventer JSJ Alkali Activated Materials. Vol 13.; 2014. doi:10.1007 / 978-94-007-7672-2_5), using as precursors different raw materials from different rocks and by-products of the steel, thermoelectric and ceramic industries, such as igneous rocks, rice husk ash, high-grade slag Petition 870200089617, dated 07 / 20 / 2020, pp. 29 / 41 25 / 25 furnace, metakaolins, kaolins, wollastonite, etc., which can form a partial or total amorphous structure detected by X-ray diffraction. Furthermore, the manufacturing process of friction material differs from the state of the art in that the liquid binder is mixed with the raw materials of the friction material as a viscous solution and / or suspension (from 100 to 50000 cP), and its processing moisture may or may not be adjusted and controlled before the shaping process, according to the process steps described throughout the invention.

[0106] The inventive concept now disclosed and exemplified in one or more ways has been treated as a trade secret and was not previously disclosed until the filing of this patent application. This trade secret is an intangible asset of the applicant.The eventual future publication of the patent application does not, in itself, constitute authorization for use by third parties, serving only as: (i) notification to third parties of the existence of said industrial secret on the filing date; (ii) unequivocal indication of its holder; and (iii) encouragement to develop new improvements based on the concept now revealed, to avoid reinvestment in the development of the same asset already held by the applicant. It is hereby warned that any commercial use requires authorization from the holder and that unauthorized use entails sanctions provided for by law. In this context, it is clarified that, from the disclosure of this inventive concept, those skilled in the art may consider other ways of implementing the invention not identical to those merely exemplified above, but that in the event of a claim for commercial use, such ways may be considered as being within the scope of the attached claims. Petition 870200089617, dated 07 / 20 / 2020, pp. 30 / 41

Claims

1 / 4 Claims 1. A manufacturing process for friction material characterized by comprising at least the following steps: a. mechanical activation of at least one inorganic precursor by means of grinding, forming a crystalline and / or amorphous structure, wherein the inorganic precursor comprises at least one of the materials belonging to the families of igneous, metamorphic or sedimentary rocks and / or by-products and co-products of the steel, thermoelectric, ceramic, mining and civil construction industries such as, for example, metakaolin, clays, basaltic rocks, granites, sandstones, carbonates, phosphates, silicates, aluminates, blast furnace slag, heavy and fly ash from coal and / or biomass, rice husk ash, glass, tailings, sludge, concentrates, demolition waste, or a combination thereof; b.a. combination of the mechanically activated inorganic precursor with at least one solution of alkali / alkaline earth metal hydroxide and / or alkali / alkaline earth metal silicate, forming the liquid binder; b. combination of at least one liquid binder with at least one complementary material, forming a mixture; c. cold forming of the mixture with predetermined temperature, pressure and compression time; and d. completion of the mixture curing with predetermined temperature and time.

2. Process, according to claim 1, characterized in that the liquid binder is a solution and / or a suspension and has a viscosity in a range between 10 to 100000 cP.

3. Process, according to claim 1, characterized in that the complementary material comprises at least one of: a. mineral filler; Petition 870260052958, dated 01 / 06 / 2026, page 17 / 24 2 / 4 b. organic fiber; c. metallic fiber; d. inorganic fiber; e. attritor; f. lubricant; g. toughener; or h. a combination of the foregoing.

4. Process, according to claim 1, characterized in that the mechanical activation step of at least one inorganic precursor occurs together with the grinding of the inorganic precursor to a particle size range of less than 500 μm.

5. A process, according to any one of claims 1 to 4, characterized in that the cold forming step of the mixture is carried out with a temperature range below 150 °C; a pressure less than or equal to 300 MPa; and a time range between 2 and 300 seconds.

6. Process, according to any one of claims 1 to 5, characterized in that the final curing step of the mixture is carried out with a temperature range of 10 to 500 °C; and in a time range of 5 minutes to 48 hours.

7. Inorganic liquid binder characterized by comprising a combination of at least one solution and at least one mechanically activated crystalline and / or amorphous inorganic precursor, wherein said solution comprises at least one alkali / alkaline earth metal hydroxide and / or at least one alkali / alkaline earth metal silicate and wherein the inorganic precursor comprises at least one of the materials belonging to the families of igneous, metamorphic or sedimentary rocks and / or by-products and co-products of the steel, thermoelectric, ceramic, mining and civil construction industries such as, for example, metakaolin, clays, basaltic rocks, granites, sandstones, carbonates, phosphates, silicates, aluminates, blast furnace slag, heavy and fly ash from coal and / or Petition 870260052958, dated 01 / 06 / 2026, page. 18 / 24 3 / 4 biomass, rice husk ash, glass, tailings, sludge, concentrates, demolition waste, or a combination of the above.

8. Use of inorganic liquid binder for the manufacture of friction material characterized by comprising a mixture of inorganic liquid binder with at least one complementary material, wherein: a.The liquid binder comprises a combination of at least one solution and at least one mechanically activated crystalline and / or amorphous inorganic precursor, wherein said solution comprises at least one alkali / alkaline earth metal hydroxide and / or at least one alkali / alkaline earth metal silicate and wherein the inorganic precursor comprises at least one of the materials belonging to the families of igneous, metamorphic or sedimentary rocks and / or by-products and co-products of the steel, thermoelectric, ceramic, mining and civil construction industries such as, for example, metakaolin, clays, basaltic rocks, granites, sandstones, carbonates, phosphates, silicates, aluminates, blast furnace slag, heavy and fly ash from coal and / or biomass, rice husk ash, glass, tailings, sludge, concentrates, demolition waste, or a combination thereof; and b. The supplementary material comprises at least one of the following: i. ii. iii. iv. v. vi.vii. viii. mineral filler; organic fiber; metallic fiber; inorganic fiber; attritor; lubricant; toughener; or a combination thereof.

9. Friction material characterized by comprising a mixture of at least one inorganic liquid binder and at least one complementary material, Petition 870260052958, dated 01 / 06 / 2026, page.19 / 24 4 / 4 wherein the binder comprises a combination of at least one solution and at least one mechanically activated crystalline and / or amorphous inorganic precursor, wherein said solution comprises at least one alkali / alkaline earth metal hydroxide and / or at least one alkali / alkaline earth metal silicate and wherein the inorganic precursor comprises at least one of the materials belonging to the families of igneous, metamorphic or sedimentary rocks and / or by-products and co-products of the steel, thermoelectric, ceramic, mining and construction industries such as, for example, metakaolin, clays, basaltic rocks, granites, sandstones, carbonates, phosphates, silicates, aluminates, blast furnace slag, heavy and fly ash from coal and / or biomass, rice husk ash, glass, tailings, sludges, concentrates, demolition waste, or a combination thereof. previous. Petition 870260052958, dated 01 / 06 / 2026, pages 20 / 24.

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