Particulate mixed oxide materials and thermal barrier compositions based thereon

Abstract

Hydrophobized particulate material comprising 30 to 95 wt.-% of a fumed mixed oxide based on silicon dioxide and oxides of at least one metal M, and 5 to 70 wt.-% of at least one IR opacifier selected from the group consisting of silicon carbide, zirconium dioxide, ilmenite, iron titanate, zirconium silicate, manganese oxide, graphite, carbon black and mixtures thereof, the metal M being selected from the group consisting of Al, Ti and Fe, wherein the content of the metal M oxide in the mixed oxide is 0.1 to 10 wt.-%.

Description

[0001] This invention relates to a hydrophobic granular material based on a silica-based mixed oxide, a method for its preparation, and a thermal insulation composition comprising such a material.

[0002] Effective insulation for residences, industrial plants, pipelines, and other applications is a significant economic issue. Most organic-based insulation materials, such as polyurethane foam, are flammable and only usable under limited temperatures. Insulation materials based on inorganic oxides, such as highly porous silica, which have been less common to date, do not exhibit these drawbacks. In contrast, when using such materials for insulation, the optimization of mechanical properties, such as particle size and mechanical stability, plays a major role.

[0003] Such silica-based insulation materials are typically based on so-called aerogels, as well as precipitated or fumed silica. More detailed information on these silica types can be found in Ullmann's Encyclopedia of Industrial Chemistry, “Silica” chapter, published online on 15.04.2008, DOI:10.1002 / 14356007.a23_583.pub3.

[0004] WO 2011 / 083174 A1 discloses a plaster that can be applied to the surface of a building to produce an insulating coating, the insulating coating comprising water, mineral and / or organic hydraulic binders and 0.5-65% by weight of at least one hydrophobic silica dry gel or aerogel powder or granular material.

[0005] WO 2014 / 090790 A1 discloses a dry mix for producing an insulating rendering, comprising 60-90 vol% hydrophobic granular silica aerogel, 0.5-30 vol% pure mineral binder, 0.2-20 vol% open-cell water-insoluble additives, 0-5 vol% reinforcing fibers, and 0-5 vol% processing additives. This insulating rendering can be prepared by mixing such a dry mix with water and subsequently curing it.

[0006] Silica aerogels, due to their specific synthesis methods, possess a porous structure highly suitable for their application in thermal insulation and are a recognized component in existing thermal insulation compositions. Unfortunately, aerogels are considerably more expensive than other types of silica, such as fumed silica, and exhibit poor thermal insulation performance at elevated temperatures. Therefore, there is a desire to develop alternative thermal insulation compositions based on other types of silica.

[0007] Simply replacing the aerogel material in the insulating composition with a corresponding fumed silica material (e.g., as disclosed in WO2006 / 097668 A1) will result in a higher thermal conductivity of the resulting composition. Although the insulating properties of such a composition can be improved to some extent by increasing the fumed silica loading, silica cannot be further introduced due to the excessively high viscosity of the final composition.

[0008] WO 2006 / 097668 A1 discloses a granular thermal insulation material comprising 30-95 wt% microporous thermal insulation material such as hydrophobic fumed silica, 5-70 wt% infrared shading agent material, 0-50 wt% particulate thermal insulation filler material, and 0-5 wt% binder material such as polyvinyl alcohol, which is prepared by mixing the components and subsequently densifying to obtain granular material with a size of 0.25 mm to 2.5 mm. The free-flowing material disclosed in WO 2006 / 097668 A1 is designed as a loose filler for high-temperature thermal insulation applications.

[0009] PCT / EP2018 / 051142 discloses a granular material with improved mechanical strength comprising hydrophobic silica and an IR shading agent. Such a material exhibits less mechanical consumption and is suitable for thermal insulation formulations. A method for preparing such a granular material includes the following steps: a) mixing hydrophilic silica with at least one IR shading agent; b) densifying the mixture obtained in step a) to produce a granular material; c) subjecting the granular material produced in step b) to heat treatment at a temperature of 200-1200°C; d) hydrophobizing the heat-treated granular material in step c) with a hydrophobic agent. In an alternative method for preparing this material, in step c), instead of heat treatment, the granular material produced in step b) is treated with ammonia.

[0010] Although the silica-based granular materials disclosed in PCT / EP2018 / 051142 are suitable for insulating formulations, there is still a need to improve the viscosity of insulating compositions containing high loads of such materials.

[0011] The problem this invention aims to solve is to provide an insulating material that is better suited for insulating compositions. More specifically, the technical problem this invention seeks to solve is to provide a silica-based insulating material suitable for preparing insulating compositions, wherein the insulating composition has a relatively high loading of the silica-based material and a relatively low viscosity, and exhibits low viscosity increase during storage. Such an insulating composition should, on the one hand, provide low thermal conductivity, and on the other hand, be well-mixable and well-suited to the surface to be insulated.

[0012] This objective is achieved by providing a hydrophobic granular material comprising 30-95% by weight of a mixed oxide based on silicon dioxide and at least one metal M (the metal M being selected from Al, Ti, and Fe, wherein the content of the metal M oxide in the mixed oxide is 0.1-10% by weight), and 5-70% by weight of at least one IR shielding agent selected from the group consisting of silicon carbide, zirconium dioxide, ilmenite, ferric titanate, zirconium silicate, manganese oxide, graphite, carbon black, and mixtures thereof.

[0013] Surprisingly and unexpectedly, given the prior art, it has now been found that this hydrophobic granular material provides a significant improvement in viscosity for both freshly prepared and stored insulating compositions compared to materials based on pure silica as described in PCT / EP2018 / 051142.

[0014] The mixed oxides of the present invention are preferably pyrolytic, i.e., prepared by pyrolysis, and therefore comprise pyrolytic (gas-phase) metal oxides. Pyrolytic (gas-phase) metal oxides are prepared by flame hydrolysis or flame oxidation. This involves the oxidation or hydrolysis of hydrolyzable or oxidizable starting materials, typically in a hydrogen / oxygen flame. Starting materials used in pyrolysis methods include organic and inorganic substances. Metal halides such as silicon tetrachloride are particularly suitable. The resulting hydrophilic metal oxides are amorphous. Gas-phase metal oxides are typically in aggregated form. "Aggregated" should be understood to mean that the so-called primary particles initially formed subsequently become firmly bonded together to form a three-dimensional network during the reaction. These primary particles are substantially non-porous and have free hydroxyl groups on their surface.

[0015] Pyrolytic mixed oxides, such as pyrolytic silica-alumina mixed oxides, are known to be used in various formulations. Therefore, US2003 / 0095905A1 discloses BET surface areas greater than 300 m². 2 A hydrophilic aluminum-silicon mixed oxide powder prepared by pyrolysis with an Al2O3 content of 0.01-99.99% by weight was found to be well dispersed in aqueous compositions, and its use as a filler in coatings, particularly inkjet materials, is recommended.

[0016] US patent 4286990 discloses a BET surface area of ​​50-200 m². 2 A silica-alumina mixed oxide, prepared by hydrophilic pyrolysis, contains 0.5-20% by weight silica and the remainder alumina. This mixed oxide was found to be thermally stable up to 1325°C and its use in insulating compositions is proposed. A specific embodiment (Example 2) illustrates the preparation of a fine hydrophilic powder with an average particle diameter of 7 nm and an alumina content of 97.5% by weight.

[0017] EP 1016932 A1 discloses a toner mixture comprising an aluminum-silicon mixed oxide prepared by pyrolysis with an alumina content of 60-70% by weight, which has been surface-treated with hexamethyldisilazane (HMDS).

[0018] It is known to prepare pyrolytic mixed oxides by simultaneously reacting at least two different metal sources in the form of volatile metal compounds, such as chlorides, in an H2 / O2 flame. An example of such oxide is the SiO2 / Al2O3 mixed oxide, which was developed by Evonik under the name... MOX 170 preparation. When preparing... At MOX 170, a mixture of SiCl4 and AlCl3 is directly hydrolyzed in a flame. Instead of chlorides, or in addition to chlorides, corresponding silanes, such as methyltrichlorosilane, trichlorosilane, etc., can be used as raw materials. (DE-A 952 891; DE-A 25 33 925; DE-A 27 02 896. These references are incorporated herein by reference in their entirety.)

[0019] The components of the mixed oxide thus prepared, such as silica and alumina in the aforementioned case, are typically uniformly distributed throughout the mixed oxide material, unlike other types of mechanical mixtures such as several metal oxides or doped metal oxides. In the latter case, for example, for a mixture of several metal oxides, there may be corresponding domains of pure oxides, which determine the local properties of such a mixture.

[0020] In a particularly preferred embodiment of the invention, the hydrophobic granular material is a pyrolytic silica-alumina mixed oxide (M = Al).

[0021] In this invention, the terms "granular material," "granules," and "granules" are used interchangeably and are understood to refer to granular, easily poured, free-flowing solid materials.

[0022] The digital median particle size of granular materials can be determined by laser diffraction particle size analysis according to ISO 13320:2009. The obtained measured particle size distribution is used to determine the median d0. 50 Defined as the granularity of the digital median, the median d 50 The particle size reflects no more than 50% of all particles. The hydrophobic granular material of the present invention can have a di greater than 10 μm, preferably 20-4000 μm, more preferably 50-3500 μm. 50 .

[0023] The hydrophobic granular material of the present invention preferably contains only particles having a size of not more than 6000 μm, preferably 50-5000 μm, and more preferably 200-4000 μm, as determined by dynamic image analysis according to ISO 13322-2:2006. For some applications, it may be preferred that the hydrophobic granular material of the present invention does not contain particles smaller than 200 μm.

[0024] The hydrophobic granular material according to the present invention can have a particle size greater than 20 μm. 2 / g, preferably 30-500m 2 / g, more preferably 50-400m 2 BET surface area / g. Also simply referred to as BET surface area, the specific surface area is determined according to DIN 9277:2014 by nitrogen adsorption according to the Brunauer-Emmett-Teller method.

[0025] The terms "hydrophobic" and "hydrophobicated" are similar in the context of this invention and refer to particles with low affinity for polar media such as water. Conversely, hydrophilic particles have high affinity for polar media such as water. The hydrophobicity of hydrophobic materials can generally be achieved by applying appropriate nonpolar groups to the surface of silica. The degree of hydrophobicity of hydrophobic materials can be determined by parameters including their methanol wettability, as described in detail, for example, on pages 5-6 of WO2011 / 076518 A1. In pure water, hydrophobic silica-based materials are completely separated from the water and float on its surface without being wetted by the solvent. Conversely, in pure methanol, the hydrophobic silica is distributed throughout the solvent volume; complete wetting occurs. In the measurement of methanol wettability, the maximum methanol content at which silica remains unwetted in the methanol / water test mixture is determined, meaning that 100% of the test material remains separated from the test mixture in an unwetted form after contact with the test mixture. The methanol content in a methanol / water mixture, expressed as a percentage by volume, is called the methanol wettability. A higher level of methanol wettability indicates a more hydrophobic material. Conversely, a lower methanol wettability indicates a less hydrophobic and more hydrophilic material.

[0026] The hydrophobic granular material of the present invention can have a methanol wettability of more than 5% by volume, preferably 10% to 80%, more preferably 15% to 70%, particularly preferably 20% to 65%, and most preferably 25% to 60% methanol content in a methanol / water mixture.

[0027] The hydrophobic granular material of the present invention comprises at least one IR-blocking agent. This IR-blocking agent reduces the infrared transmittance of the thermal insulation material, and thus minimizes heat transfer due to radiation.

[0028] The IR opacifier can be selected from the group consisting of silicon carbide, zirconium dioxide, ilmenite, ferric titanate, zirconium silicate, manganese oxide, graphite, carbon black, and mixtures thereof. The particle size of the opacifier is typically between 0.1 μm and 25 μm.

[0029] The granular material contains 30% to 95%, preferably 40% to 90%, more preferably 50% to 85% by weight of a silica-based mixed oxide, and 5% to 50%, preferably 10% to 40%, more preferably 15% to 30% by weight of a light-blocking agent.

[0030] The thermal conductivity of the hydrophobic granular material of the present invention can be measured according to EN 12667:2001 using a protective heat plate (GHP) and a heat flow meter. The average measurement temperature is 10°C and the contact pressure is 250 Pa; the measurement is performed under standard pressure in an air atmosphere.

[0031] The thermal conductivity of the hydrophobic granular material of the present invention in bed form, measured according to EN 12667:2001 at an average measurement temperature of 10°C, in air atmosphere, and at a contact pressure of 250 Pa under standard pressure, is preferably less than 50 mW / (m*K), more preferably 10-45 mW / (m*K), particularly preferably 12-40 mW / (m*K), and most preferably 15-35 mW / (m*K).

[0032] The hydrophobic particulate material of the present invention preferably has a relatively low content of free hydroxyl groups, such as silanol hydroxyl groups Si-OH on the surface. The hydrophobic particulate material preferably has a hydroxyl density of not more than 0.3 mmol OH / g, more preferably less than 0.2 mmol OH / g, and most preferably less than 0.1 mmol OH / g. The hydroxyl density of silica or silica-containing materials can be determined by reaction with lithium aluminum hydride using the method disclosed by Mathias and G. Wannemacher in Journal of Colloid and Interface Science, Vol. 125, pp. 61-68 (1988). Using the corresponding BET surface area of ​​the material used, the hydroxyl density in mmol OH / g can be converted to OH / nm. 2 The granular material used in the compositions of the present invention preferably has a content of not more than 1 OH / nm. 2 More preferably, less than 0.5 OH / nm 2 More preferably, less than 0.3OH / nm 2 The optimal value is less than 0.1 OH / nm. 2 hydroxyl density.

[0033] The compacted density of various powdery or coarse-grained materials can be determined according to DIN ISO 787-11:1995, "General methods of test for pigments and extenders – Part 11: Determination of tamped volume and apparent density after tamping". This involves measuring the apparent density of the bed after stirring and compaction. The granular materials of the present invention have a compacted density of up to 450 g / L, preferably 50-300 g / L, more preferably 100-280 g / L, and more preferably 120-250 g / L.

[0034] The remarkable feature of the hydrophobic granular material of the present invention is its exceptionally high stability coupled with low compaction density. Therefore, with this hydrophobic granular material, it is generally advisable to eliminate or reduce undesirable material wear and breakage during the preparation of compositions containing such particles, such as the insulating compositions of the present invention.

[0035] The present invention further provides a method (A) for preparing hydrophobic granular materials according to the present invention, the method comprising the following steps:

[0036] a) Mixing a hydrophilic silica-based mixed oxide with at least one IR-shielding agent;

[0037] b) Densify the mixture obtained in step a) to produce a hydrophilic granular material;

[0038] c) subject the hydrophilic granular material produced in step b) to heat treatment at a temperature of 200-1200°C;

[0039] d) The hydrophilic granular material that has undergone heat treatment in step c) is hydrophobized with a hydrophobic agent.

[0040] The present invention also provides another method (B) for preparing hydrophobic granular materials according to the present invention, the method comprising the following steps:

[0041] a) Mixing a hydrophilic silica-based mixed oxide with at least one IR-shielding agent;

[0042] b) Densify the mixture obtained in step a) to produce a hydrophilic granular material;

[0043] c) Treat the hydrophilic granular material produced in step b) with ammonia;

[0044] d) The hydrophilic granular material treated with ammonia in step c) is hydrophobized with a hydrophobic agent.

[0045] Steps a) and b) of the methods (A) and (B) according to the invention can be performed as independent separate stages, or alternatively combined in a single method step.

[0046] The mixing of the hydrophilic silica-based mixed oxide with at least one IR-shielding agent according to step a) of method (A) or method (B) can be carried out using any suitable mixing equipment known to those skilled in the art. Any mixer or mill that allows for good homogenization, such as a paddle mixer, fluidized bed mixer, centrifugal mixer, or air-swept mixer, is suitable for carrying out step a) of the method according to the invention. Particularly suitable mixers are those that can be used to further compact the material being mixed, such as plowshare mixers, disc mills, or ball mills.

[0047] According to step b) of method (A) or method (B), densifying the mixture obtained in step a) to produce granular material can be carried out by degassing or compaction.

[0048] The heat treatment of the hydrophilic granular material produced in step b) of method (A) can be carried out at a temperature of 200-1500°C, preferably 400-1400°C, preferably 500-1200°C, more preferably 600-1100°C, and most preferably 800-1100°C.

[0049] In step c) of the method (B) according to the invention, the hydrophilic granular material produced in step b) is treated with ammonia, preferably gaseous ammonia. The duration of step c) of the method (B) according to the invention depends on factors including chemical composition, particle size of the material, and temperature. The duration is typically from 10 minutes to 100 hours, preferably from 0.5 hours to 20 hours. The preferred temperature here is 0-200°C, more preferably 20-100°C.

[0050] For treatment with ammonia in step c) of method (B) according to the invention, ammonia can be introduced together with the hydrophilic granular material to be treated into a chamber designed for this purpose. This chamber must simply meet the requirement of maintaining the pressure and temperature required in the method according to the invention. The pressure difference Δp = p2 – p1 (where p1 = pressure in the chamber before the introduction of gaseous ammonia, p2 = pressure in the chamber when the introduction of gaseous ammonia stops) is preferably greater than 20 mbar, more preferably 50 mbar to 5 bar, particularly preferably 100 mbar to 500 mbar, and most preferably 200 mbar to 400 mbar.

[0051] In addition to ammonia, in step c) of method (B), steam may preferably be added to the pre-generated granular material at a relative vapor pressure of 50% to 95%.

[0052] The hydrophobic agent used in step d) of method (A) or method (B) may comprise a silicon compound, preferably selected from the group consisting of halosilanes, alkoxysilanes, silazanes and siloxanes.

[0053] More preferably, this silicon compound is a liquid compound having at least one alkyl group and a boiling point less than 200°C. It is preferably selected from the group consisting of: CH3SiCl3, (CH3)2SiCl2, (CH3)3SiCl, C2H5SiCl3, (C2H5)2SiCl2, (C2H5)3SiCl, C3H8SiCl3, CH3Si(OCH3)3, (CH3)2Si(OCH3)2, (CH3)3SiOCH3, C2H5Si(OCH3)3, (C2H5)2Si(OCH3)2, (C2H5)3SiOCH3, C8H 15 Si(OC2H5)3, C8H 15 Si(OCH3)3, (H3C)3SiNHSi(CH3)3, (H3C)3SiOSi(CH3)3, and mixtures thereof. Particularly preferred are (H3C)3SiNHSi(CH3)3, (H3C)3SiOSi(CH3)3, and (CH3)2SiCl2.

[0054] In the method (A) or method (B) according to the invention, after steps b) and / or c) and / or d), the particle sizes of granular materials of different sizes may be separated from each other in such a way that only one or more particle sizes having a specific particle size are separated and further used.

[0055] Another subject of the invention is a thermal insulation composition comprising the hydrophobic granular material of the invention. The thermal insulation composition according to the invention may contain at least one binder that bonds the portions of the cured composition together and optionally to one or more fillers and / or other additives, thereby improving the mechanical properties of the cured composition. This binder may contain organic or inorganic substances. The binder optionally contains reactive organic substances. Organic binders may, for example, be selected from the group consisting of (meth)acrylates, alkyd resins, epoxy resins, gum arabic, casein, vegetable oils, polyurethanes, silicone resins, waxes, cellulose gums, and mixtures thereof. Such reactive organic substances can cause the curing of the thermal insulation composition used, for example, by polymerization, crosslinking reactions, or other types of chemical reactions. This curing can be carried out, for example, by thermal methods or under the action of UV radiation or other radiation. Single-component (1-C) and multi-component systems, particularly two-component systems (2-C), can be used as binders. Particularly preferred for the invention are (meth)acrylate-based binders and silicone binders (preferably as single-component systems) and epoxy resins (preferably as two-component systems).

[0056] Most organic binder materials, such as (meth)acrylates and epoxy resins, have specific thermal limitations and cannot be used at temperatures above 150°C. In contrast, siloxane-based materials (silicone resins) are generally more thermally stable and can be applied at temperatures up to about 600°C without thermal degradation. Such organosiloxane binders (silicone resins) or hybrid systems containing organosilicon components and other organic components are particularly preferred for use in the compositions of the present invention.

[0057] In addition to or as an alternative to organic binders, the insulating compositions of the present invention may contain inorganic curable substances. Such inorganic binders, also known as mineral binders, have essentially the same function as organic binders: binding the additives together. Furthermore, inorganic binders are classified into non-hydraulic binders and hydraulic binders. Non-hydraulic binders are water-soluble binders that cure only in air, such as quicklime, dolomitic lime, gypsum, and anhydrous gypsum. Hydraulic binders are binders that cure in air and in the presence of water and are insoluble in water after curing. They include hydraulic lime, cement, and masonry cement. Mixtures of different inorganic binders may also be used in the insulating compositions of the present invention.

[0058] The thermal insulation composition of the present invention preferably contains 5-60% by weight of hydrophobic granular material and 40-95% by weight of inorganic and / or organic binder.

[0059] The curing of the insulating composition can be carried out by at least partial polymerization and / or solvent evaporation. Depending on the system used, this step can preferably be carried out at a temperature of 0-500°C, particularly preferably 5-400°C, and very particularly preferably 10-300°C. Curing can be carried out in the presence of air or under conditions where oxygen is excluded, such as in a protective gas atmosphere of nitrogen or carbon dioxide. The step can be carried out under standard pressure or under reduced pressure, such as under a vacuum.

[0060] In addition to hydrophobic granular materials and binders, the thermal insulation compositions according to the invention may further contain at least one solvent and / or filler and / or other additives.

[0061] The solvent used in the compositions of the present invention may be selected from the group consisting of water, alcohols, aliphatic and aromatic hydrocarbons, ethers, esters, aldehydes, ketones, and mixtures thereof. For example, the solvent used may be water, methanol, ethanol, propanol, butanol, pentane, hexane, benzene, toluene, xylene, diethyl ether, methyl tert-butyl ether, ethyl acetate, or acetone. Particularly preferably, the solvent used in the insulating composition has a boiling point of less than 300°C, and particularly preferably less than 200°C. During the curing of the insulating composition according to the present invention, this relatively volatile solvent can be readily evaporated or vaporized. Most preferably, the insulating composition of the present invention contains water as the sole solvent.

[0062] The hydrophobic granular materials and insulating compositions based thereon according to the present invention can generally be used for thermal and / or sound insulation, particularly for sound and / or thermal insulation of walls, roofs, houses, and for thermal insulation of industrial plants, components of industrial equipment, pipes, etc. Example

[0063] Preparation of silica granular material A (comparative example)

[0064] Preparation of hydrophobic silica granular materials containing IR-shielding agents according to PCT / EP2018 / 051142:

[0065] mix

[0066] 20 wt% of 1000F silicon carbide (Carsimet) (manufacturer: Keyvest) and 80 wt% of... were mixed using a Minox PSM 300HN / 1MK plow mixer. 200 hydrophilic silica (BET = 200m) 2 / g, Manufacturer: EVONIK Resource Efficiency GmbH) Mixed.

[0067] densification

[0068] The above-prepared material was densified using Grenzebach densifying rollers (Vacupress VP 160 / 220). The mixture of 200 and silicon carbide is densified. The compacted density of the obtained granular material is adjusted by the applied contact pressure, roller speed, and pressure reduction. The applied vacuum is less than 300 mbar absolute value. The roller speed is 5 rpm, and the pressure is 2000 N.

[0069] Sintering / hardening

[0070] From The subsequent thermosetting was carried out in a chamber furnace of GmbH's XR 310. For this purpose, multiple layers of a bed with a maximum height of 5 cm were subjected to a temperature program. The heating rate was 300 K / h until the target temperature of 950 °C was reached; the holding time was 3 hours; then the sample was allowed to cool (without active cooling) until it was removed.

[0071] Hydrophobicity

[0072] The final hydrophobication of the thermosetting granular material in the gas phase is carried out at elevated temperatures. For this purpose, hexamethyldisilazane (HMDS) as a hydrophobic agent is evaporated, and this is done by a reduced pressure method according to Example 1 of WO 2013 / 013714A1. The sample is heated to over 100°C in a desiccator and then evacuated. Subsequently, gaseous HMDS is introduced into the desiccator until the pressure rises to 300 mbar. After purging the sample with air, it is removed from the desiccator.

[0073] Screening / Grading

[0074] To obtain the desired particle size, the thermosetting granular material is first fed into a vibrating mill (manufacturer: FREWITT) with a 3150 μm sieve mesh size to establish an upper limit for the particle size distribution and thus remove particles larger than this limit. This is followed by the desired particle size classification, such as 200-1190 μm or 1190-3150 μm. This is done using an LS18S vibrating screen from Sweco. The average particle size of the sieved particle size distribution of granular material A (200-1190 μm) is d. 50 =580μm.

[0075] Preparation of silica-alumina granular material B according to the present invention

[0076] Silica-alumina granular material B was prepared similarly to silica granular material A, except that it was prepared using... MOX 170 (a pyrolytic silica-alumina mixed oxide containing approximately 1% by weight of alumina, BET = 170m) 2 / g, Manufacturer: EVONIK Resource Efficiency GmbH) Substitute raw materials 200, and the sintering temperature in the sintering / hardening step is reduced to 850℃. The average particle size of the sieved particle size class of granular material B, ranging from 200 to 1190 μm, is d. 50 =440μm.

[0077] The adhesive used

[0078] Adhesive A: Acronal Eco 6270 (manufacturer: BASF); acrylic functionalized adhesive system.

[0079] Adhesive B: Coatosil DR (manufacturer: Momentive); a siloxane-functionalized adhesive system.

[0080] Viscosity measurement

[0081] The dynamic viscosity of the formulation (a mixture of binder and granular material) was measured using a Brookfield DV2T Extra rotational viscometer. The spindle and rotation speed were selected according to the viscosity range given in the manual.

[0082] A general experimental description of measuring the viscosity of compositions containing granular materials after different storage times.

[0083] Preparation of the formulation:

[0084] The binder (276g) was filled into a cylindrical glass container with a diameter of 9.5cm and stirred with a propeller stirrer at 600rpm. The granular material (24g, sieve particle size 200-1190μm) was gradually added to the stirred binder, and stirring was continued until a homogeneous mixture was obtained, that is, all the granular material was incorporated into the binder-containing mixture.

[0085] Measurement:

[0086] The dynamic viscosity of all samples was measured immediately after preparation. Samples were sealed with an impermeable cap and additionally sealed with Parafilm M foil. These sealed samples were stored without stirring at two different temperatures (25°C and 40°C), opened after a defined storage period for dynamic viscosity measurements as described above, and then sealed again for further storage. All samples were measured twice weekly over three weeks to observe their thickening behavior.

[0087] Example

[0088] Comparative Example 1

[0089] According to general experimental descriptions, granular material A (sieve particle size 200-1190 μm) was tested with binder A at 25°C.

[0090] Example 1

[0091] According to general experimental descriptions, granular material B (sieve particle size 200-1190 μm) was tested with binder A at 25°C.

[0092] Comparative Example 2

[0093] According to general experimental descriptions, granular material A (sieve particle size 200-1190 μm) was tested with binder A at 40°C.

[0094] Example 2

[0095] According to general experimental descriptions, granular material B (sieve size 200-1190 μm) was tested with binder A at 40°C.

[0096] Comparative Example 3

[0097] According to general experimental descriptions, granular material A (sieve particle size 200-1190 μm) was tested with binder B at 25°C.

[0098] Example 3

[0099] According to general experimental descriptions, granular material B (sieve size 200-1190 μm) was tested with binder B at 25°C.

[0100] Comparative Example 4

[0101] According to general experimental descriptions, granular material A (sieve particle size 200-1190 μm) was tested with binder B at 40°C.

[0102] Example 4

[0103] According to general experimental descriptions, granular material B (sieve particle size 200-1190 μm) was tested with binder B at 40°C.

[0104] Comparative Example 5

[0105] Granular material A (sieve size 200-1190 μm) was pulverized for 1 minute at 2000 rpm using a GRINDOMIX GM 300 (Retsch) grinder to obtain material with d 50 Fine powder with an average particle size of 208 μm. The powder was tested with binder A at 25°C according to general experimental descriptions.

[0106] Example 5

[0107] Granular material B (sieve size 200-1190 μm) was pulverized for 1 minute at 2000 rpm using a GRINDOMIX GM 300 (Retsch) grinder to obtain material with d 50 Fine powder with an average particle size of 158 μm. The powder was tested with binder A at 25°C according to general experimental descriptions.

[0108] Viscosity measurements after different storage times are summarized in Table 1. These results clearly demonstrate that the compositions (Examples 1-5) containing granular materials based on mixed oxides according to the present invention provide significantly lower viscosity compared to similar materials based on pure silica (Comparative Examples 1-5).

[0109] Table 1

[0110]

Claims

1. A hydrophobic granular material comprising 30-95% by weight of a mixed oxide based on silicon dioxide and at least one metal M, and 5-70% by weight of at least one IR shading agent selected from the group consisting of silicon carbide, zirconium dioxide, ilmenite, iron titanate, zirconium silicate, manganese oxide, graphite, carbon black and mixtures thereof, wherein the metal M is selected from Al, Ti and Fe, and the content of the oxide of the metal M in the mixed oxide is 0.1-10% by weight; Its features are, The mixed oxide is a mixed oxide of pyrolytic silicon dioxide and aluminum oxide; and The granular material has a digital median particle size d greater than 10 μm. 50 .

2. The hydrophobic granular material according to claim 1, Its features are, The granular material has a methanol wettability of 10% to 80% methanol in a methanol / water mixture.

3. The hydrophobic granular material according to any one of claims 1-2, Its features are, The granular material does not contain particles smaller than 200 μm.

4. The hydrophobic granular material according to any one of claims 1-2, Its features are, The hydrophobic granular material has a particle size of 50-400 μm. 2 / g of BET surface area.

5. The hydrophobic granular material according to any one of claims 1-2, Its features are, The granular material has a compacted density of 50-300 g / L.

6. The hydrophobic granular material according to any one of claims 1-2, Its features are, The granular material has a hydroxyl density of not more than 0.3 mmol OH / g.

7. A method for preparing a hydrophobic granular material according to any one of claims 1-6, the method comprising the following steps: a) Mixing a hydrophilic silica-based mixed oxide with at least one IR-shielding agent; b) Densify the mixture obtained in step a) to produce a hydrophilic granular material; c) subject the hydrophilic granular material produced in step b) to heat treatment at a temperature of 200-1200°C; d) The hydrophilic granular material that has undergone heat treatment in step c) is hydrophobized with a hydrophobic agent.

8. A method for preparing a hydrophobic granular material according to any one of claims 1-6, the method comprising the following steps: a) Mixing a hydrophilic silica-based mixed oxide with at least one IR-shielding agent; b) Densify the mixture obtained in step a) to produce a hydrophilic granular material; c) Treat the hydrophilic granular material produced in step b) with ammonia; d) The hydrophilic granular material treated with ammonia in step c) is hydrophobized with a hydrophobic agent.

9. A thermal insulation composition comprising a hydrophobic granular material according to any one of claims 1-6.

10. The thermal insulation composition according to claim 9, comprising at least one organic binder selected from the group consisting of (meth)acrylates, alkyd resins, epoxy resins, gum arabic, casein, vegetable oils, polyurethanes, silicone resins, hybrid systems comprising organosilicon components and other organic components, waxes, cellulose gums, and mixtures thereof.

11. The insulating composition according to any one of claims 9-10, comprising at least one inorganic binder selected from the group consisting of quicklime, dolomitic lime, gypsum, anhydrous gypsum, hydraulic lime, cement, masonry cement, and mixtures thereof.

12. Use of the granular material according to any one of claims 1-6 for thermal insulation and / or sound insulation.

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