EP4143144A1

EP4143144A1 - Method for producing heat-insulating composite particles, composite particles and use thereof

Info

Publication number: EP4143144A1
Application number: EP21724210.6A
Authority: EP
Inventors: Kurt SCHÜMCHEN; Julian FASOLA; Andreas Gabriel
Original assignee: Interbran Raw Materials GmbH
Current assignee: Interbran Raw Materials GmbH
Priority date: 2020-04-30
Filing date: 2021-04-30
Publication date: 2023-03-08
Also published as: WO2021219847A1

Abstract

The invention relates to a method for producing heat-insulating composite particles and to the composite particles that are obtainable by this method and to their use. The method is characterized in that, for the purpose of producing heat-insulating composite particles, a porous particulate material, such as, for example, volcanic rock, (expanded) perlite, (expanded) vermiculite, pumice, foamed glass and expanded glass, expanded clay, expanded slate, tuff, lava gravel, lava sand, is mixed with deagglomerated silicic acid, e.g. pyrogenic and/or precipitated silica acid, and/or with an aerogel, and wherein preferably the porous particulate material is coated with the silicic acid and/or the aerogel.

Description

METHOD FOR MANUFACTURING THERMAL INSULATING COMPOSITE PARTS, COMPOSITE PARTS AND THEIR USE

The present invention relates to the technical field of thermal insulation, in particular thermal insulating additives for binder systems.

In particular, the present invention relates to a method for producing heat-insulating composite particles and the composite particles obtainable with the method. In addition, the present invention relates to the use of the composite particles for the production of building materials and dry building material mixtures which contain the composite particles.

The invention also relates to plastering mortar compositions which contain the dry building material mix or the composite particles and a thermal insulation board obtainable therefrom.

To improve the thermal insulation properties of mineral binder systems, for example based on lime and / or cement, it is customary to use heat-insulating aggregates, in particular lightweight aggregates. Due to their porosity, the aggregates improve the thermal conductivity of the resulting building materials, in particular of mortar and plaster. The lightweight aggregates used are usually highly porous materials such as expanded vermiculite or expanded perlite.

With the help of these additives, it is possible to optimize the thermal insulation properties of the intrinsically highly thermally conductive mineral binder systems so that the resulting mortars and plasters can be used, for example, as insulation plasters.

Expanded perlite is often used as a surcharge due to its good mechanical strength, general availability and low acquisition costs.

Through the use of porous mineral aggregates, mortars and plasters can be produced which have significantly better thermal insulation properties than standard systems and which are also open to water vapor diffusion. This means that moisture trapped in a building or masonry can be released into the environment. This is an advantage mineral systems compared to the often plastic-based thermal insulation composite systems (ETICS), which usually consist of environmentally harmful and water-vapor-tight polystyrene or polyurethane.

However, mineral systems, in particular expanded perlite, have a disadvantage compared to plastic-based thermal insulation materials in that they have high thermal conductivities in comparison, so that thin insulation systems based exclusively on mineral systems, such as perlite, are not accessible.

There are other additives, such as silica aerogels in particular, which can significantly reduce the thermal conductivity of mineral insulation systems, but these are often not sufficiently mechanically resilient to be able to be introduced into industrially manufactured dry building materials and applied by machine.

Another, in principle good thermal insulation material is fumed silica, which, however, only has extremely small particle sizes and is also relatively expensive to purchase, so that fumed silica is seldom used as the sole additive. Furthermore, when fumed silica is used as an additive in mineral binder systems, in particular lime-cement binders, a deterioration in the thermal insulation properties is often observed.

It is true that the mechanical properties, in particular the compressive strength and tear resistance of the cured binder, are significantly improved through the use of silica, in particular fumed silica, but at the expense of poorer thermal insulation properties. This is due to the fact that the use of silica often increases the density of the binder system, as the silica fibers and particles are deposited in the pores of the binder system and in the spaces between the aggregates and thus lead to a compaction of the material. If both heat-insulating fillers, in particular expanded perlite, and pyrogenic silica are added to a plastering mortar, the thermal conductivity of the hardened plastering mortar is higher than that of comparable mixtures without pyrogenic silica. However, since silicas and especially fumed silicas are in principle well suited for improving the thermal insulation properties of mineral binder systems and also always improving the mechanical properties as well as the fire resistance of the binder systems, attempts have been made to incorporate silica with thermally insulating fillers into mineral binder systems.

EP 2 576 929 B1 describes a thermal insulation powder mixture which has at least one silica and at least one fiber material with a fiber diameter of 1 to 50 μm and optionally foamed or expanded powders such as perlite. The powder mixtures are pressed in order to obtain moldings.

Furthermore, EP 3490 954 B1 describes a method for producing a hydrophobic silica-containing thermal insulation material, in which hydrophilic and hydrophobic silica are crosslinked by means of a silicon-based binder, for example a silane or silazane, and the mixture is then pressed into molded bodies.

Furthermore, silica aerogels are also suitable in principle as excellent thermal insulation materials, as they have a very high porosity and a pore volume of up to 99.8%. However, silica aerogels have the major disadvantage that they can only be mechanically stressed to a limited extent and are therefore destroyed by the forces acting during mixing or mixing when they are introduced into building material mixtures for thermal insulation purposes. In addition, the production of aerogels is complex, so that their use is always associated with significantly increased costs.

The state of the art therefore still lacks heat-insulating materials which have improved heat-insulating properties compared to conventional mineral aggregates, are preferably in particle form and a large number of inorganic binder systems can be incorporated easily and flexibly. In particular, there is also a lack of a heat-insulating system which, for example, can be incorporated into dry mixes of conventional inorganic binders, in particular cement-containing binders, and which can then be processed like conventional mortars or plasters. One object of the present invention is thus to be seen in avoiding, or at least reducing the disadvantages associated with the prior art, as outlined above.

In particular, it is an object of the present invention to provide an improved thermal insulation material which has improved thermal insulation properties compared to conventional thermal insulation materials such as expanded perlite.

Another object of the present invention is to provide a thermal insulation material which can be incorporated easily and without problems into a large number of inorganic binder systems and which can be produced inexpensively.

The subject matter of the present invention according to a first aspect of the present invention is thus a method for producing heat-insulating composite particles according to claim 1; further advantageous refinements of this aspect of the invention are the subject of the related subclaims.

The present invention according to a second and third aspect of the present invention further relates to composite particles according to the invention according to claim 18 or 19.

The present invention according to a fourth aspect of the present invention also further provides the use of the composite material according to the invention according to claim 20.

Yet another subject matter of the present invention according to a fifth aspect of the present invention is a dry building material mix according to claim 21.

Yet another subject matter of the present invention according to a sixth aspect of the present invention is a plaster mortar according to claim 22.

Finally, according to a seventh aspect of the present invention, the present invention again further provides a thermal insulation panel according to claim 23. It goes without saying that advantages, peculiarities, features, configurations and embodiments as well as advantages or the like, which in the following - for the purpose of avoiding unnecessary repetitions - are only explained for one aspect of the invention, of course also apply accordingly with regard to the other aspects of the invention, without this needing to be explicitly mentioned.

It also applies that all of the values or parameters or the like mentioned below can in principle be determined or determined using standardized or standardized or explicitly stated determination methods or determination methods that are familiar to the person skilled in the art.

In addition, it goes without saying that weight or quantity-related percentages are selected by the person skilled in the art in such a way that the total result is 100%.

Having said that, the present invention is described in more detail below:

The present invention - according to a first aspect of the present invention - is thus a method for producing heat-insulating composite particles, wherein a porous particulate material is mixed with deagglomerated silica and / or with airgel, preferably deagglomerated silica.

Because, as the applicant has surprisingly found, it is possible to significantly improve the thermal insulation properties of porous particles, such as expanded perlite, by mixing the porous particulate material with deagglomerated silica and / or airgel.

The mixture forms a layer of silica or airgel on the surface of the porous particulate material, the porous material is coated with the silica and / or the airgel, so to speak. In this way, on the one hand, an improvement in the thermal insulation properties of the particulate material is achieved and, on the other hand, when silica is used, it is prevented that silica is incorporated into the when incorporated into an inorganic binder system Pores of a binder system or in gaps between aggregates and thus leads to a compression of the particular inorganic binder system, whereby its thermal conductivity is improved.

If silica is used, which is preferred within the scope of the invention, it is essential that the silica is deagglomerated before mixing with the particulate material. Silica is usually in the form of agglomerates in the high micrometer to millimeter range. If these agglomerates are incorporated into insulation systems or mixed with aggregates, they are deposited in the pores of the binder system or in gaps between aggregates, so that overall a deterioration in the thermal insulation properties is observed. When using deagglomerated silica, on the other hand, it is observed that when mixed with porous particles, fibrous structures of silica form on the surface of the porous particles, which on the one hand anchors or hooks on the surface of the porous particles and on the other hook with other fibers, see above that a shell is formed on the surface of the particles. This shell is not necessarily closed or uniform everywhere, but rather has irregularities and often gaps, but is firmly connected to the porous particles. Similar structures are also observed when using airgel, in particular silica airgel. However, this behavior is particularly pronounced when using pyrogenic silica, the use of which is particularly preferred in the context of the present invention.

The porous particulate material serves as a carrier material. The result is composite particles with a core / filling structure which have significantly improved thermal insulation properties compared to the carrier material used, the material of the core.

In addition, it is surprisingly observed that the composite particles obtainable with the method according to the invention, when incorporated into mineral insulation systems, have a positive effect on the mechanical properties of the resulting cured systems, in particular of plasters and mortars, so in particular the compressive strength and the tendency to crack are significantly improved. As stated above, in the context of the present invention, silica and / or airgel are used to produce the composite particles, the use of silica being preferred. If a silica is used, it has proven useful if the silica is selected from pyrogenic silica, precipitated silica and mixtures thereof, preferably pyrogenic silica.

As far as the porous particulate material is concerned, a large number of materials, in particular porous particles, come into consideration here. However, inorganic or mineral materials are preferably used. The porous particulate material, in particular carrier material, can have both closed pores and open pores. Closed pores - also known as closed porosity - are closed inside the material and have no connection to the environment. In contrast to closed pores, open pores end on the outer surface of the material and are therefore in contact with the environment.

With the method according to the invention, composite particles with improved thermal insulation are accessible in a simple and inexpensive manner, which can be incorporated easily and flexibly into a large number of binder systems, in particular inorganic binder systems. The composite particles obtainable with the method according to the invention can preferably be incorporated into cement-containing binder systems and thus used for the production of plastering mortars, in particular thermal insulation plasters, or thermal insulation boards, for example for interior construction.

A special feature of the composite particles obtainable with the method according to the invention is in particular that they are preferably free of further fibers, i.e. contain at most fibers based on silica and / or airgel, preferably silica, preferably pyrogenic silica. This means that the composite materials according to the invention do not have to be admixed with further fibers, in particular glass fibers or mineral fibers, for stabilization.

In addition, by mixing hydrophobic and hydrophilic silicas and / or aerogels or silicas and / or aerogels with different hydrophobicity, the hydrophobic properties of the resulting Adjust composite particles in a targeted manner. In this way it is possible to obtain composite particles which are adapted to a high degree to the particular binder system and the intended use.

The compounds summarized under the name "silica" in the context of the present invention are polycondensation products of orthosilicic acid Si (OH) ₄ , the empirical formula of which converges to S1O2, ie silicon dioxide, as condensation progresses. The silicas used in the context of the present invention are therefore often also referred to as silicon dioxides. Polysilicic acids are divided into precipitated silica - also called precipitated silicon dioxide - and pyrogenic silica - also called pyrogenic silicon dioxide - according to the way they are produced. Both precipitated silicas and pyrogenic silicas are synthetic amorphous silicon dioxides.

Precipitated silica is usually obtained by the polycondensation reaction of sodium silicate solution after acidification with mineral acids, whereby water glass, i.e. a water-containing polysilicic acid, is formed first, which is then condensed to amorphous colloidal particles and dried.

Pyrogenic silica is generally formed by the reaction of silicon tetrachloride SiCU in an oxyhydrogen flame, i.e. in an ignited mixture of elemental hydrogen and elemental oxygen.

Both precipitated silicas and pyrogenic silicas are colorless powders with a low bulk density and a large specific surface. Precipitated silicas and pyrogenic silicas are often used for similar purposes and are used as fillers, for example to improve the mechanical resistance of coatings.

However, on closer inspection, precipitated silica and fumed silica differ considerably in their physical and chemical properties, which is why they have different effects on the properties of the systems in which they are used. Pyrogenic silica is usually more mechanically resilient than precipitated silica and has a higher density: Pyrogenic silica usually has BET specific surfaces of 20 to 600 m ² / g and densities of about 2.2 g / cm ³ . The primary particle size is usually Usually between 5 and 60 nm, while the particle size of the aggregated primary particles usually varies in the range from a few 100 nm to approx. 2 mm.

Precipitated silica, on the other hand, has a BET specific surface area in the range from 30 to 800 m ² / g with a density of 1.9 to 2.1 g / cm ³ . The primary particle size is between 50 and 100 nm, while the particle size of the agglomerated primary particles is 1 to 50 μm. In the context of the present invention, all specific BET surface areas are preferably determined in accordance with DIN ISO 9277: 2003-05.

In the context of the present invention, as stated above, pyrogenic silicas are preferably used.

In the context of the present invention it is possible that hydrophilic silicas or also hydrophobic silicas are used. Hydrophilic silicas can be incorporated more easily and more homogeneously into inorganic binder systems, in particular plaster mortar systems, the components of which often consist of hydrophilic mineral components.

In the context of the present invention, a hydrophilic silica is to be understood as meaning a silica which has as few, preferably no, organic groups, in particular no alkyl groups, but is preferably terminated with polar chemical groups, in particular silanol groups. Hydrophilic substances usually refer to polar organic or inorganic substances which are readily miscible with water. This also applies, for example, to solid systems, which are referred to as hydrophilic if they are well wetted by water.

Hydrophobically modified silicas, usually also referred to as hydrophobic silicic acid, are modified with organic groups, in particular with alkylsilanes, in order to reduce the hydrophilicity of unmodified silicic acid and, for example, to increase the compatibility of the silicas with organic systems. In the context of the present invention, it is possible that both hydrophilic and hydrophobic silica or mixtures thereof are used in order to increase the hydrophilicity or hydrophobicity of the composite particles obtainable with the method according to the invention for the respective application purpose or to tailor the binder system into which they are to be incorporated.

As stated above, aerogels are highly porous solids, the volume of which consists of pores up to 99.8% by volume. In the context of the present invention, primarily silicate-based aerogels or hybrid aerogels containing silicon dioxide and a further component are used, the use of silicate-based aerogels being preferred. Silicate-based aerogels, so-called silica aerogels, are derived from orthosilicic _{acid H 4} _{Si0 4} and its condensation products. They are highly porous solids with a pore volume of generally 95 to 99.8% by volume, based on the total volume of the airgel. Due to their high porosity, aerogels are poor conductors of heat and sound and are therefore of interest for the development of insulation materials.

However, the field of application of aerogels in the field of insulation and insulation materials has so far been largely limited to a few special applications, since aerogels, due to their high porosity, represent extremely fragile solid-state structures which are destroyed even with relatively low mechanical stress. In addition, the preparation of aerogels is very cost-intensive and requires a lot of equipment, which is why aerogels have so far not been able to be used economically in insulation and insulation materials.

Aerogels, in particular also silica aerogels, can be both hydrophilic and hydrophobic. A hydrophobic treatment is often carried out as part of the airgel synthesis in order to enable water or polar organic solvents to be removed from the pores of the airgel without the pore structure of the airgel being destroyed. The hydrophobization is often done with silanes or siliconates.

As has been shown in the context of the present invention, not only silicas but also the much more sensitive aerogels can be used in the context of the present invention. During the production of the composite particles according to the invention, some of the airgel particles are destroyed, but the remaining, undestroyed proportion is sufficient to significantly improve the thermal insulation properties of the carrier material. According to the use of silica described above, both hydrophilic and hydrophobic aerogels, in particular silica aerogels, or their can be used within the scope of the invention Mixtures are used. Mixtures of aerogels and silicas can also be used. However, the best results are obtained when silicas, in particular fumed silicas, are used.

In the context of the present invention it is usually provided that the porous particulate material is selected from mineral materials.

In the context of the present invention, it has proven particularly useful if the porous particulate material is selected from the group consisting of volcanic rock, perlite, in particular expanded perlite, vermiculite, in particular expanded vermiculite, pumice, foam and expanded glass, expanded clay, expanded slate, tuff , Lava gravel, lava sand, and their mixtures.

Particularly good results are obtained in this context if the porous particulate material is selected from the group consisting of perlite, in particular expanded perlite, vermiculite, in particular expanded vermiculite, pumice, foam and expanded glass, expanded clay, expanded slate, tuff, and mixtures thereof.

According to a preferred embodiment of the present invention it is provided that the porous particulate material is selected from the group consisting of perlite, in particular expanded perlite, and vermiculite, in particular expanded vermiculite, and mixtures thereof.

It is very particularly preferred in the context of the present invention if the porous particulate material is perlite, in particular expanded perlite. Specially expanded perlite is available inexpensively in large quantities and has long been tried and tested as a heat-insulating additive that is open to water vapor diffusion for mineral binder systems, in particular for cement-containing binder systems.

As far as the particle size of the porous particulate material used is concerned, it can vary within wide ranges. In the context of the present invention, however, it has proven useful if the porous particulate material has absolute particle sizes in the range from 0.01 to 7 mm, in particular from 0.05 to 4 mm, preferably 0.1 to 3.5 mm, preferably 0.15 to 3 mm, particularly preferably 0.2 to 2.5 mm.

In addition, provision is generally made for the porous particulate material to have pores with pore sizes in the range from 0.05 to 800 μm, in particular 0.1 to 700 μm, preferably 0.5 μm to 500 μm, preferably 1 μm to 300 μm, particularly preferably 2 to 200 μm. Pore sizes in the range mentioned seem to be particularly suitable for anchoring a coating made of silica and / or airgel.

As far as the composite particles obtainable by the process according to the invention are concerned, their particle size can also vary within wide ranges. However, it has generally proven useful if the composite particles have absolute particle sizes in the range from 0.01 to 10 mm, in particular 0.1 to 8 mm, preferably 0.15 to 5 mm, preferably 0.2 to 4 mm, particularly preferably 0 , 25 to 3 mm.

Particles with the aforementioned particle sizes can easily be incorporated as additives into commercially available binder systems, in particular cement- or lime-based binder systems.

In addition, the composite particles in bulk generally have a thermal conductivity at 25 ° C. in the range from 0.020 to 0.045 W / (mK), in particular 0.022 to 0.040 W / (mK), preferably 0.024 to 0.038 W / (mK), preferably 0.026 up to 0.035 W / (mK), particularly preferably 0.028 to 0.035 W / (mK).

By mixing or coating porous particulate materials, in particular expanded perlite, with pyrogenic silica, a significant reduction in thermal conductivity can be achieved compared to pure carrier materials, such as expanded perlite, which has thermal conductivity values of approx. 0.040 at 25 ° C up to 0.045 W / (mK).

In addition, it is generally provided within the scope of the present invention that the composite particles have a bulk density in the range from 30 to 150 kg / m ³ , in particular 40 to 100 kg / m ³ , preferably 50 to 80 kg / m ³ , preferably 70 to 80 kg / m ³ . The composite particles obtainable with the method according to the invention are thus suitable for use as lightweight aggregates, with they also have good thermal insulation properties due to their low density and high porosity.

Furthermore, it is generally provided that the composite particles have the combustibility A1 or A2 according to DIN 4102. The composite particles obtainable by the process according to the invention can thus be incorporated into a large number of binder systems without increasing the combustibility of the system. In addition, a further advantage of the composite particles obtainable according to the invention can be seen in the fact that they consist of inorganic mineral materials which, on the one hand, are non-combustible and, on the other hand, have good water vapor permeability and consequently counteract the formation of mold when used in or on buildings.

As already stated above, it is essential in the context of the present invention that the porous particles are mixed or coated with silica and / or airgel, preferably silica. As far as the silica or airgel is concerned, a large number of silicas and / or aerogels can be used here. In particular, it is also possible within the scope of the present invention to mix different silicas and / or aerogels. In the context of the present invention, preference is given to using pyrogenic silicas, either in combination or mixture with precipitated silicas and / or aerogels, or alone or in mixture or combination with further pyrogenic silicas. In the context of the invention, it is preferred if pyrogenic silicic acid alone or mixtures or combinations of different pyrogenic silicas are used.

In the context of the present invention, it is generally provided that the silica or the airgel have a specific surface area (BET) of more than 20 μg, in particular more than 50 μg, preferably more than 80 μg, particularly preferably more than 100 m ² / g.

Likewise, it can be provided that the silica or the airgel has a specific surface area (BET) in the range from 20 to 500 m ² / g, in particular 50 to 450 m 2 / g, preferably 80 to 450 m 2 / g, preferably 100 to 400 m 2 ² / g. When using silicas, the present invention preferably provides for the silica in aqueous dispersion with 4% by weight of silica, based on the dispersion, to have a pH in the range from 3 to 7, in particular 4 to 6 .

In the context of the present invention it is provided that the silica is deagglomerated before mixing with the particulate materials, since corresponding composite particles can only be obtained with deagglomerated silica. In the context of the present invention, it has proven useful if the pyrogenic silica, after deagglomeration, has particle sizes in the range from 5 to 250 μm, in particular 10 to 200 μm, preferably 15 to 180 μm, preferably 20 to 150 μm, particularly preferably 25 to 100 μm, having.

In contrast, aerogels are preferably used without deagglomeration in order to prevent extensive destruction of the airgel particles.

In order to break up the silica granules or agglomerates, it has proven useful if the silica is deagglomerated with the introduction of high shear forces or, for example, also by sieving. If the silica is deagglomerated by introducing high shear forces, it has proven useful if the silica is used at shear rates of more than 20 m / s, in particular more than 30 m / s, preferably more than 40 m / s, preferably more than 50 m / s, is deagglomerated.

In the context of the present invention, deagglomeration is preferably achieved by sieving, in particular by means of a vibrating sieve.

As stated above, the silica used according to the invention is in the form of silica granules before deagglomeration. The silica granules generally have particle sizes in the range from 0.1 to 3 mm, in particular 0.2 to 2 mm. Before deagglomeration, the silica usually has a tamped density in the range from 20 to 200 g / l, preferably 30 to 150 g / l, preferably 40 to 100 g / l.

In order to produce composite particles, the particulate materials as well as the silica and / or the airgel are mixed. It is particularly preferred in the context of the present invention if the porous particulate material and the silica or the airgel carefully, in particular with little low mechanical stress, can be mixed. As the applicant has found, it is completely sufficient if the porous particulate materials are coated with the silica and / or the airgel by careful or gentle mixing. This leads to the formation of, in particular, fibrous structures made of silica and / or airgel on the surface of the porous particles, which on the one hand adhere to the pores and the other surface of the particles or interlock there and on the other hand adhere and interlock with one another.

In the context of the present invention it is therefore provided in particular that the porous particulate material and the silica or the airgel are mixed with the introduction of low shear forces. Particularly good results are obtained in this context if the porous particulate material and the silica or the airgel with a shear rate of not more than 5 m / s, in particular not more than 3 m / s, preferably not more than 2 m / s, preferably not more than 1 m / s, are mixed.

As far as the duration for which the particulate materials and the silica or airgel are mixed, this can vary within wide ranges, in particular depending on the respective conditions and the layer thickness of silica and / or airgel to be achieved on the particulate carrier material .

In the context of the present invention, however, it has proven useful if the porous particulate material and the silica or the airgel are mixed for at least 1 minute, in particular at least 2 minutes, preferably at least 5 minutes, preferably at least 10 minutes.

Likewise, it can be provided within the scope of the present invention that the porous particulate material and the silica or the airgel over a period of 1 minute to 2 hours, in particular 2 minutes to 1.5 hours, preferably 5 minutes to 1 hour, preferably 10 minutes to 1 hour.

In the context of the present invention, the porous particulate material is preferably coated with the silica and / or the airgel. As already explained above, by mixing the silica or the airgel with the porous particulate material apparently fibrous structures made of silica and / or airgel formed on the surface of the porous carrier material, which are anchored to the surface of the particles or hook there as well as hook with each other, so that gradually a - albeit uneven and not completely closed - layer of silica and / or airgel is formed on the particulate material.

In the context of the present invention it is usually provided that the coating with the silica and / or the airgel is varied in the range from 5 to 600 μm, in particular 5 to 500 μm, preferably 8 to 400 μm, preferably 10 to 300 μm. The layer thicknesses can be varied in particular by adjusting the ratio of the starting materials to one another and also the mixing time or the repetition of the mixing process. Composite particles specially tailored to the respective application can be obtained.

With regard to the ratio in which the porous particulate material and the silica and / or the airgel are mixed, this can likewise vary within wide ranges, depending on which layer thicknesses are to be achieved. In the context of the present invention, however, it has proven useful if the porous particulate material and the silica or the airgel in a volume-related ratio of porous particulate material to silica or airgel in the range from 4: 1 to 1:30, in particular 3: 1 to 1:20, preferably 2: 1 to 1:15, preferably 1.5: 1 to 1:10, can be mixed.

Equally good results are obtained when the porous particulate material and the silica or the airgel are in a weight-related ratio of porous particulate material to silica or airgel in the range from 0.1: 1 to 40: 1, in particular 0.2: 1 up to 30: 1, preferably 0.3: 1 to 20: 1, preferably 0.5: 1 to 20: 1, can be mixed.

Particularly good results are obtained in the context of the present invention when the porous particulate material is mixed with different silicas and / or aerogels, in particular silicas, preferably pyrogenic silicas. The different silicas or aerogels can be silicas or aerogels with different physical or chemical properties, in particular with different particle sizes or different densities, but also with different rather hydrophilicity. According to a preferred embodiment of the present invention, it is provided that the porous particulate material is first mixed with a hydrophilic silica and / or a hydrophilic airgel, and then the coated particles thus obtained are mixed again with a hydrophobic silica and / or a hydrophobic airgel will. The silicas used must in any case be deagglomerated before use. By initially using a hydrophilic silica and / or a hydrophilic airgel, a good bond between the coating and the usually mineral and hydrophilic carrier material can be achieved to obtain hydrophobized particles.

According to a preferred embodiment of the present invention it is provided that the porous particulate material and the silica or the airgel are mixed several times. In particular, it can be provided in this context that the multiple mixing processes are carried out one after the other. In this way, layer thicknesses of the coating with silica and / or airgel can be adjusted in a targeted manner. In the context of the present invention, it has proven useful if the porous particulate material and the silica or the airgel 2 to 10 times, in particular 2 to 7 times, preferably 2 to 5 times, preferably 2 to 3 times, particularly preferably 2 times, mixed.

If multiple mixing processes are carried out, it has proven useful if, for each individual layering process, the porous particulate material and the silica or the airgel in a volume-related ratio of porous particulate material to silica or airgel in the range of 4: 1 to 1: 5, in particular 2: 1 to 1:10, preferably 1.5: 1 to 1:10, preferably 1: 1 to 1: 5, is mixed.

Equally, it can be provided that for each coating process the porous particulate material and the silica or the airgel in a weight-related ratio of porous particulate material to silica or airgel in the range from 0.1: 1 to 80: 1, in particular 0, 2: 1 to 50: 1, preferably 0.3: 1 to 40: 1, preferably 0.5: 1 to 30: 1, can be mixed. In the context of the present invention it is thus provided according to a preferred embodiment that the porous particulate material is coated several times with the silica and / or the airgel.

Particularly good results are obtained in this connection if the porous particulate material is applied twice to 10 times, in particular 2 to 7 times, preferably 2 to 5 times, preferably 2 to 3 times, particularly preferably 2 times times, is coated with silica and / or airgel.

If multiple coatings are carried out, it has proven useful if each coating is carried out with a layer thickness in the range from 2 to 200 μm, in particular from 3 to 150 μm, preferably from 5 to 100 μm, preferably from 5 to 80 μm. The multiple coating processes are preferably carried out in such a way that the aforementioned total thicknesses for the coating are retained.

If, within the scope of the present invention, a layer of hydrophilic silica or hydrophilic airgel is first applied to the porous particulate material and then a layer of hydrophobic silica or hydrophobic airgel is applied, it has proven useful if the ratio - either by weight or based on volume - from hydrophilic to hydrophobic silica or airgel in the range from 10: 1 to 1: 4, in particular 8: 1 to 1: 2, preferably 7: 1 to 1: 1, preferably 5: 1 to 1: 1.

In the context of the present invention it is preferably provided that the porous particulate material is mixed with an IR scattering agent before, during or after mixing with the silica and / or the airgel.

An IR scattering agent, also called an IR opacifier, is a substance, in particular in particle form, which minimizes the infrared permeability of the composite particles and thus prevents the transfer of heat by radiation as far as possible. The infrared radiation is preferably reflected or diffusely scattered by the IR scattering means.

The IR scattering agents can, for example, be mixed together with the silica or the airgel and the porous particulate material. However, it is also possible to use IR scattering agents prior to mixing with the silica or to mix the airgel with the porous material or to mix the composite particles, ie after the porous particulate material has been mixed with the silica or the airgel, with the IR scattering agent; good results are always achieved. In particular, the thermal conductivity of the composite particles can be further reduced by using the IR scattering agent.

As for the IR diffuser, it can also be selected from a variety of materials. However, it has proven useful if the IR scattering agent is selected from the group consisting of carbon, in particular carbon black and / or graphite, silicon carbide, llmenite, zirconium silicate, iron oxide, titanium dioxide, zirconium oxide, manganese oxide, iron titanate and mixtures thereof.

It is particularly preferred in this context if the IR scattering agent is selected carbon, in particular carbon black and / or graphite, and silicon carbide.

As for the amount in which the IR scattering agent is used, this can also be varied depending on the results to be achieved in each case. Usually, however, it is provided within the scope of the present invention that the IR scattering agent is used in an amount of 0.01 to 20% by weight, in particular 0.02 to 18% by weight, preferably 0.03 to 14% by weight. %, preferably 0.04 to 12% by weight, particularly preferably 0.05 to 10% by weight, based on the total amount of porous particulate material and silica or airgel, is used. Thus, within the scope of the present invention, small amounts of IR scattering agent are sufficient to further reduce the thermal conductivity of the material obtained.

In addition, it is preferably provided within the scope of the present invention that the porous particulate material and the IR scattering agent are mixed carefully, i.e. with the introduction of low shear forces. It is preferably provided that the porous particulate material and the IR scattering agent are mixed under the same conditions as the porous particulate material and the silica or the airgel.

In particular, it can be provided within the scope of the present invention that the porous particulate material and the IR scattering agent have a shear rate of not more than 5 m / s, in particular not more than 3 m / s, preferably not more than 2 m / s, preferably not more than 1 m / s, are mixed.

In addition, within the scope of the present invention it can furthermore be provided that further additives, in particular processing aids, are also mixed with the other starting materials. However, this is preferably not provided, so that preferably only two materials, namely the porous particulate material and silica or airgel or three materials, namely porous particulate material, silica or airgel and IR scattering medium, are used to produce the composite particles. In the case of the silica or the airgel it can of course be provided that several types of silica or airgel are used, as described above.

According to a preferred embodiment of the present invention, the method is carried out in such a way that

(A) in a first process step, silica is deagglomerated and

(b) in a second process step following the first process step (a), a porous particulate material is mixed, in particular coated, with the deagglomerated silica and optionally airgel.

All of the aforementioned embodiments, advantages and special features apply equally to this preferred embodiment. In particular, it is also preferably provided that the particulate porous material and the silica or the airgel are mixed with the introduction of low thrust forces. It is also particularly possible that several coating processes are carried out with the silica or the airgel, in particular also with different silicas or aerogels, a hydrophilic silica or a hydrophilic airgel being used initially in a first coating step and one in a subsequent step hydrophobic silica or a hydrophobic airgel.

It shows the figure representations according to

1 shows a composite particle according to the invention with a core made of expanded perlite which is coated with graphite and hydrophilic fumed silica, and 2 shows a composite particle according to the invention with a core made of expanded perlite, which is first coated with hydrophilic silica and graphite and then with hydrophobic fumed silica.

Another object of the present invention - according to a second aspect of the present invention - is a composite particle obtainable by the method described above.

For further details in this regard, reference can be made to the method according to the invention in order to avoid unnecessary repetitions, which apply accordingly to the composite particles according to the invention,

Again the further invention - according to a third aspect of the present invention - is a composite particle which is obtainable in particular by the method described above, the composite particles having a core made of a porous material and a shell, in particular a coating, containing silica and / or airgel, in particular silica.

The composite particle preferably consists of a core made of a porous material and a shell (coating) which contains silica or airgel and optionally an IR scattering agent.

Usually it is provided within the scope of the present invention that the composite particles have a thermal conductivity at 25 ° C in the range from 0.020 to 0.045 W / (mK), in particular 0.022 to 0.040 W / (mK), preferably 0.024 to 0.038 W / (mK) , preferably 0.026 to 0.035 W / (mK), particularly preferably 0.0328 to 0.035 W / (mK).

For further relevant details on the composite particles according to the invention, reference can be made to the preceding statements on the method according to the invention, which apply accordingly in relation to the composite particles according to the invention.

Again another subject of the present invention - according to a fourth aspect of the present invention - is the use of the aforementioned composite particles for the production of building materials, in particular of Insulating materials, such as insulating plaster, insulation boards or thermal insulation composite systems, preferably thermal insulation boards.

The composite particles according to the invention are outstandingly suitable for use in all types of insulation systems and can be used there in particular as a substitute for plastics or purely mineral-based insulation materials.

For further details on the use according to the invention, reference can be made to the statements relating to the above aspects of the invention, which apply accordingly in relation to the use according to the invention.

Another object of the present invention - according to a fifth aspect of the present invention - is a dry building material mixture containing the aforementioned composite particles.

The dry building material mix is preferably suitable for the production of plaster mortars and insulating plasters, but for the production of molded bodies, such as thermal insulation boards.

The dry building material mix usually has the composite particles in amounts of 10 to 90% by weight, in particular 10 to 70% by weight, preferably 15 to 65% by weight, preferably 20 to 60% by weight, particularly preferably 30 to 50% by weight .-%, based on the dry mix of building materials.

In general, the dry building material mix has at least one binder composition, the dry building material mix preferably having only one binder composition.

In the context of the present invention, it has proven useful if the dry building material mixture contains the binder composition in amounts of 5 to 80% by weight, in particular 15 to 70% by weight, preferably 30 to 60% by weight, preferably 35 to 55% by weight. -%, particularly preferably 40 to 50% by weight, based on the dry building material mixture.

Particularly good results are obtained when the binder composition has at least one cement-based binder, preferably cement, preferably Portland cement, particularly preferably white cement. The advantage of The use of cement-based binders means that they set hydraulically, ie by adding water, and form particularly resilient and permanent solid systems.

In this context, it has proven useful if the binder composition contains the cement-based binder in amounts of 1 to 79% by weight, in particular 3 to 50% by weight, preferably 5 to 40% by weight, preferably 8 to 30% by weight. %, particularly preferably 10 to 25% by weight, based on the dry building material mixture.

Likewise, particularly good results are obtained in the context of the present invention if the binder composition has at least one lime-based binder, in particular hydraulic lime and / or hydrated lime, preferably hydraulic lime. Hydrated lime is calcium hydroxide Ca (OH) 2, which is obtained from quicklime (CaO) by dry adsorption. Hydraulic lime is calcium hydroxide Ca (OH) 2 to which small amounts of a hydraulic binder, in particular cement, are added.

If the dry building material mix according to the invention contains a lime-based binder, it has proven useful if the binder composition contains the lime-based binder in amounts of 1 to 79% by weight, in particular 5 to 60% by weight, preferably 10 to 50% by weight, preferably 15 to 45% by weight, particularly preferably 20 to 40% by weight, based on the dry building material mix. With the aforementioned amounts of cement-based or lime-based binding agent, particularly durable and stable plastering mortars can be obtained.

According to a preferred embodiment of the present invention, the binder composition has at least one cement-based binder and at least one lime-based binder, in particular in the aforementioned amounts.

As far as the ratio of cement-based binder to lime-based binder is concerned, this can also vary within wide ranges. However, it has been found that particularly resistant and outstandingly heat-insulating plaster mortar and from these other building materials, such as insulation boards, are obtained if the binder composition is based on weight The ratio of cement-based binder to lime-based binder in the range from 5: 1 to 1:10, in particular 3: 1 to 1: 8, preferably 1: 1 to 1: 5, preferably 1: 2 to 1: 3.

In the context of the present invention it can also be provided that the dry building material mixture contains fibers, in particular inorganic, preferably mineral fibers. The use of fibers can further increase the strength and mechanical resistance of the resulting materials. The use of inorganic fibers, in particular mineral inorganic fibers, is preferred.

If the dry building material mix has fibers, it has proven useful if the fibers are selected from calcium silicate fibers, glass fibers, wollastonite fibers, carbon fibers, carbon nanotubes and mixtures thereof. It is particularly preferred in the context of the present invention if the fibers are selected from calcium silicate fibers, glass fibers, wollastonite fibers and mixtures thereof. Particularly good results are obtained when the fibers are calcium silicate fibers.

In this context, it has proven useful if the dry building material mix is based on the fibers in amounts of 0.1 to 5% by weight, in particular 0.2 to 2% by weight, preferably 0.2 to 1% by weight the dry building material mix.

In addition, it can be provided within the scope of the present invention that the dry building material mixture contains at least one additive, in particular at least one additive. In this context, particularly good results are obtained when the additive is selected from the group of liquefiers, thickeners, retarders, accelerators, stabilizers (stabilizers), rheology control agents, additives to adjust the water retention capacity (water retention agents), dispersants, sealants, air entrainment agents and mixtures thereof .

If the dry building material mixture according to the invention contains an additive, the dry building material mixture usually contains the additive in amounts of 0.01 to 10% by weight, in particular 0.1 to 5% by weight, preferably 0.3 to 3% by weight, preferably 0.5 to 1% by weight, based on the dry building material mix. According to a preferred embodiment of the present invention, the dry building material mix contains

(A) Composite particles in amounts of 10 to 90% by weight, in particular 10 to 70% by weight, preferably 15 to 65% by weight, preferably 20 to 60% by weight, particularly preferably 30 to 50% by weight %, based on the dry mix of building materials,

(B) at least one cement-based binder in amounts of 1 to 79% by weight, in particular 3 to 50% by weight, preferably 5 to 40% by weight, preferably 8 to 30% by weight, particularly preferably 10 to 25% % By weight, based on the dry building material mix,

(C) at least one lime-based binder in amounts of 1 to 79% by weight, in particular 5 to 60% by weight, preferably 10 to 50% by weight, preferably 15 to 45% by weight, particularly preferably 20 to 40 % By weight, based on the dry building material mix,

(D) optionally fibers in amounts of 0.1 to 5% by weight, in particular 0.2 to 2% by weight, preferably 0.2 to 1% by weight, based on the dry building material mix, and

(E) at least one additive in amounts of 0.01 to 10% by weight, in particular 0.1 to 5% by weight, preferably 0.3 to 3% by weight, preferably 0.5 to 1% by weight %, based on the dry mix of building materials.

As far as the bulk density of the dry building material mix according to the invention is concerned, this can likewise vary within wide ranges. Usually, however, the dry building material mix according to the invention has a bulk density in the range 80 to 650 kg / m ³ , in particular 90 to 600 kg / m ³ , preferably 100 to 500 kg / m ³ , preferably 110 to 400 kg / m ³ .

For further details on the dry building material mix according to the invention, reference can be made to the above statements on the other aspects of the invention, which apply accordingly in relation to the dry building material mix according to the invention.

Again another object of the present invention - according to a sixth aspect of the present invention - is a plaster mortar, in particular re an insulating plaster, obtainable from the aforementioned dry mix of building materials and / or containing the aforementioned composite particles.

In the context of the present invention, particularly good results are obtained when the plaster mortar is mixed with water in amounts of 70 to 300% by weight, in particular 80 to 250% by weight, preferably 90 to 200% by weight, based on the Dry building material mix, is available. The plaster mortar according to the invention can be made up and also processed like a conventional plaster mortar known from the prior art.

In the context of the present invention it is preferred if the hardened plaster mortar has a water vapor diffusion resistance number m, determined according to DIN EN ISO 12542, in the range from 2 to 9, in particular 3 to 7, preferably 4 to 6. As previously mentioned, the plaster mortar according to the invention is characterized in that it is open to diffusion and moisture can be released from the masonry to the environment, which counteracts the formation of mold and algae and also increases the durability of the thermal insulation system.

The hardened plaster mortar usually has a thermal conductivity in the range from 0.030 to 0.55 W / (mK), in particular 0.035 to 0.042 W / (mK), preferably 0.035 to 0.040 W / (mK).

For further details on the plastering mortar according to the invention, reference can be made to the above statements on the aforementioned aspects of the invention, which apply accordingly in relation to the plastering mortar according to the invention.

Finally, another subject matter of the present invention - according to one aspect of the present invention - is a molded body, in particular a thermal insulation board, obtainable from the aforesaid dry building material mix or the aforesaid plaster mortar and / or containing the aforesaid composite particles.

The shaped body is particularly characterized in that it preferably has a thermal conductivity in the range from 0.030 to 0.55 W / (mK), in particular 0.035 to 0.042 W / (mK), preferably 0.035 to 0.040 W / (mK). As far as the thickness of the shaped body according to the invention, in particular the thermal insulation board, is concerned, it can vary within wide ranges. In the context of the present invention, however, particularly good results are obtained when the shaped body has a thickness in the range from 1 to 20 cm, in particular from 1.5 to 15 cm, preferably from 1.5 to 10 cm, preferably from 2 to 8 cm.

For further details on this aspect of the invention, reference can be made to the preceding statements on the other aspects of the invention, which apply accordingly in relation to the molded body according to the invention.

The subject matter of the present invention is illustrated below in a non-limiting manner using an exemplary embodiment.

Embodiment

The production of composite particles according to the invention is described in detail below.

1. Production of hydrophilic composite particles

40 l of expanded perlite with particle sizes between 0.6 and 2.5 mm are placed in a tumble mixer with a capacity of 200 liters. The perlite has a bulk density of approx. 50 g / l and a thermal conductivity of 40 mW / (mK).

Then 0.4 l of graphite powder with a carbon content of 99.5% and an average grain size of 4 μm (D50 = μm) are added and then mixed for 5 minutes at a speed of 200 revolutions / minute.

Subsequently, 21 l of hydrophilic fumed silica with a tamped density of 50 g / l, a BET surface area of approx. 380 m ² / g and a vibrating sieve with a mesh size of 2 mm are sieved to break up the agglomerates. The deagglomerated silica is then added to the mixture of graphite and perlite and mixed for a further 10 minutes at 250 revolutions / minute in a tumble mixer. Hydrophilic composite particles are obtained.

1 shows a light microscope image of a particle of expanded perlite coated with hydrophilic fumed silica and graphite. In Fig. 1 it can be seen that the surface and in particular the pores of the expanded perlite are covered with pyrogenic silica and that fiber-like or structures are formed on the surface of the perlite, which adhere firmly to there.

2. Production of hydrophilic composite particles

The composite particles coated with hydrophilic fumed silica obtained under 1. are mixed with 4 l of hydrophobic fumed silica with a tamped density of 60 g / l and a BET surface area of approx. 220 m ² / g. The hydrophobic fumed silica was also sieved beforehand with a vibrating sieve with a mesh size of 2 mm in order to break up the agglomerates.

After the hydrophobic pyrogenic silica has been added to the hydrophilic composite particles, mixing is continued for 10 minutes at a speed of 250 revolutions / minute in a tumble mixer.

Approx. 50 l of hydrophobized, coated pearlite particles with a bulk density of approx. 70 g / l and a thermal conductivity of 31 mW / (mK) are obtained.

2 shows a light microscope image of a composite particle according to the invention which is obtained after the process has ended, i.e. which is first mixed with graphite and hydrophilic silica and then mixed with hydrophobic silica.

Both the hydrophilic and the hydrophobic composite particles according to the invention can be incorporated into binder systems in an outstanding manner.

Claims

Patent claims:

1. A method for producing heat-insulating composite particles, characterized in that a porous particulate material is mixed with deagglomerated silica and / or an airgel, in particular deagglomerated silica.

2. The method according to claim 1, characterized in that the silica is selected from fumed silica, precipitated silica and mixtures thereof, preferably fumed silica.

3. The method according to claim 1 or 2, characterized in that the porous particulate material is selected from the group consisting of volcanic rock, perlite, in particular expanded perlite, vermiculite, in particular expanded vermiculite, pumice, foam and expanded glass, expanded clay, expanded slate, Tuff, lava gravel, lava sand, and mixtures thereof.

4. The method according to any one of the preceding claims, characterized in that the composite particles have absolute particle sizes in the range from 0.01 to 10 mm, in particular 0.1 to 8 mm, preferably 0.15 to 5 mm, preferably 0.2 to 4 mm , particularly preferably 0.25 to 3 mm.

5. The method according to any one of the preceding claims, characterized in that the composite particles in bulk have a thermal conductivity at 25 ° C in the range of 0.020 to 0.045 W / (mK), in particular 0.022 to 0.040 W / (mK), preferably 0.024 to 0.038 W / (mK), preferably 0.026 to 0.035 W / (mK), particularly preferably 0.028 to 0.035 W / (mK).

6. The method according to any one of the preceding claims, characterized in that the composite particles have a bulk density in the range from 30 to 150 kg / m ³ , in particular 40 to 100 kg / m ³ , preferably 50 to 80 kg / m ³ .

7. The method according to any one of the preceding claims, characterized in that the silica after deagglomeration has particle sizes in the loading ranging from 5 to 250 gm, in particular 10 to 200 gm, preferably 15 to 180 gm, preferably 20 to 150 gm, particularly preferably 25 to 100 gm.

8. The method according to any one of the preceding claims, characterized in that the porous particulate material and the silica and / or the airgel are carefully mixed, in particular with low mechanical stress.

9. The method according to any one of the preceding claims, characterized in that the porous particulate material is coated with the silica and / or the airgel.

10. The method according to claim 9, characterized in that the layer thickness of the coating with the silica and / or the airgel varies in the range from 5 to 600 gm, in particular 5 to 500 gm, preferably 8 to 400 gm, preferably 10 to 300 gm will.

11. The method according to any one of the preceding claims, characterized in that the porous particulate material and the silica and / or the airgel in a volume-related ratio of mineral porous particulate material to silica and / or airgel in the range of 4: 1 to 1 : 30, in particular 3: 1 to 1:20, preferably 2: 1 to 1:15, preferably 1.5: 1 to 1:10, can be mixed.

12. The method according to any one of the preceding claims, characterized in that the porous particulate material and the silica and / or the airgel in a weight ratio of porous particulate material to silica and / or airgel in the range from 0.1: 1 to 40: 1, in particular 0.2: 1 to 30: 1, preferably 0.3: 1 to 20: 1, preferably 0.5: 1 to 20: 1, can be mixed.

13. The method according to any one of the preceding claims, characterized in that the porous particulate material is mixed with different silicas and / or aerogels, in particular different silicas, preferably different pyrogenic silicas.

14. The method according to any one of the preceding claims, characterized in that the porous particulate material and the silica and / or the airgel are mixed several times.

15. The method according to any one of the preceding claims, characterized in that the porous particulate material is mixed with an IR scattering agent before, during or after mixing with the silica and / or the airgel.

16. The method according to claim 15, characterized in that the IR scattering agent is selected from the group consisting of carbon, in particular carbon black, graphite, silicon carbide, llmenite, zirconium silicate, iron oxide, titanium dioxide, zirconium oxide, manganese oxide, iron titanate and mixtures thereof.

17. The method according to claim 15 or 16, characterized in that IR-

Scattering agent in an amount of 0.01 to 20% by weight, in particular 0.02 to 18% by weight, preferably 0.03 to 14% by weight, preferably 0.04 to 12% by weight, particularly preferred 0.05 to 10% by weight, based on the total amount of porous particulate material and silica and / or airgel, is used.

18. Composite particles obtainable by a method according to any one of claims 1 to 17.

19. Composite particles, in particular according to claim 18, characterized in that the composite particles have a core made of a porous material and a shell (coating) containing silica and / or aerogels, in particular silica, preferably pyrogenic silica.

20. Use of composite particles according to one of claims 18 or 19 for the production of building materials, in particular insulating materials, such as insulating plaster, insulating boards or thermal insulation composite systems, preferably thermal insulation boards.

21. Dry building material mixture containing composite particles according to one of claims 18 or 19.

22. Plaster mortar, in particular insulating plaster, obtainable from a dry building material mix according to claim 21 and / or containing composite particles according to one of claims 18 or 19.

23. Shaped body, in particular thermal insulation board, obtainable from the dry building material mix according to claim 21 and / or containing composite particles according to one of claims 18 or 19.